Hybrid scan display

Abstract

A hybrid scan display emitters for emitting light and a plurality of light modulators operated in binary mode and switching between two states including a light transmitting state for transmitting light and a light shielding state for shielding light. Each image is divided in a number of parts, and the sequence of image parts for each image are interleaved resulting in an interleaved sequence.

Description

[0001] Hybrid Scan Display

[0002] DESCRIPTION

[0003] The present disclosure is directed to a new type of display - referred to as “the disclosed display” in the following.

[0004] The display has directional pixel technology, and it may be called hybrid scan display (HSD display), because an image pixel is defined in one dimension by a light emitting layer / backplane and in another dimension by a light modulator layer / frontplane, which are both scanned in order to display the image. This is contrary to a LED-backlit LCD display where the image is generated in the frontplane, and the disclosed display has at least as many light emitters as it has light modulators / liquid crystal cells or even a greater number of light emitters than light modulators. In fact, it may have as many light emitters as there are pixels.

[0005] Thus, it is a different type of display compared to lenticular displays or parallax barrier displays and does not build or modify on any of these types of displays.

[0006] A display may also be referred to as a monitor or television or screen.

[0007] The disclosed display is suitable for directing images to a plurality of viewing re- gions / zones in front of the display, e.g. for emitting light to a plurality of active viewing zones including a first active viewing zone and a second active viewing zone. It may allow multiple users to see multiple individual, artifact-free stereoscopic images, for example individual perspective images. The display may therefore constitute an autostere- oscopic display or a multiview display.

[0008] % viewing zone

[0009] A viewing zone is defined as an active viewing zone / region when there is an observing eye in that viewing zone. Light is not emitted to non-active viewing zones not withstanding the option that 3D content may be displayed to some observers (with eyes in active viewing zones) and 2D content may be displayed to other observers.

[0010] With 3D content or simply 3D is meant information that defines images to the eyes of an observer that when combined in the brain of the observer results in a depth perception. An example could be a 3D movie. It could also be a 3D movie where the controller of the display may generate a look around effect, e.g. the observer's head and eyes movements will increase information about the 3D objects being displayed - when the observer moves and has a new perspective (angle to the scene) the controller may generate a perspective of the scene corresponding to the new perspective based on the two original images showing the scene. The two original images are the images recorded with the stereo camera used when recording the movie. A neural network may for example be used to generate the new perspective view, e.g. a new right eye image as a function of the original right eye image and a new left eye image as a function of the original left eye image.

[0011] In the present disclosure and when referring to the disclosed display the term “viewing zone” is to be understood as “active viewing zone” unless mentioned otherwise.

[0012] An inactive viewing zone or non-active viewing zone is a viewing zone that is not to receive any light, e.g. it is a viewing zone that is awaiting light. Otherwise, there would be cross talk, e.g. an eye receives light that it should not receive - light intended for another eye.

[0013] A don’t care viewing zone is neither an active viewing zone or an inactive viewing zone, but a viewing zone where it does not matter if light is emitted to that viewing zone. This may be used for maintaining a DC balance in liquid crystal cells.

[0014] The display can be configured to have various angular resolution of viewing zones, such as one viewing zone per 1 degree, and can therefore be used to view 3D contents for a very high number of observers. It can also be used simply to show a different image in each viewing zone (called multiview display).

[0015] Thus, the disclosed display constitutes an implementation of a multiview display, an autostereoscopic or an automultiscopic display for a plurality of users with no loss of pixel resolution and with the possibility of look around effect.

[0016] Historically, a 3D effect / perception has been achieved with a so called lenticular display or a parallax barrier display.

[0017] Comparison to parallax barrier displays In a parallax barrier display it is the barriers between the slits that block light for achieving a parallax effect and thereby a 3D effect, e.g. the term parallax refers to the effect of a displacement or difference in the apparent position of an object viewed along two different lines of sight, and the barriers block the line of sight between a right eye and left eye pixels and the line of sight between a right eye and left eye pixels respectively. Hence the reason for the name of that type of display.

[0018] The purpose of the slits between the barriers in a parallax barrier display is not to emulate an ideal lens moving between different positions during a multiplexing cycle as is the case for the new Disclosed display, e.g. in a parallax barrier display a large fraction, typically around 50%, of the barrier is open at a time. A problem with this principle is, that a large number of undesired light rays are emitted. This causes artifacts, such as image crosstalk, and in practice reduce use cases to a single observer in a restricted viewing zone.

[0019] Multiplexed parallax barrier display

[0020] A parallax barrier may be time multiplexed. The barrier of a time multiplexed parallax barrier display may be implemented with liquid crystal cells in order to have control of the “sweet spot” of the parallax barrier display, e.g. the position of the observer can be tracked and based on that it can be determined which liquid crystal cells should be closed and act as a barrier. This can improve the resolution of the image and reduce artifacts to some degree for a single observer, or alternatively for two observers located in very restricted observation / viewing zones. However, even though in some practical implementations of a parallax barrier display each slit may have a width such that there is some focusing power, this is not something that is used to generate a 3D effect, because as mentioned it is the light blocking of the barrier that is used to achieve the parallax effect and thereby the 3D effect, e.g. the slit is not acting as a horizontally fully illuminated vertical aperture defining the horizontal position of observed pixels like in a lenticular display as is the case in the Disclosed display, but rather the slit is defining an opening through which a pixel in it’s whole can be observed, hence the pixel’s horizontal position is defined by the pixel’s position on the display.

[0021] In addition, even though a slit in a practical implementation would have some focusing effect such a slit is not scanned such that it moves during a multiplexing cycle (MP cycle), but typically two sets of slits are alternately opened and closed. This is also why the barrier can be implemented as an opaque layer of static slits in a more simple configuration of a parallax barrier display. This is not something that is possible in the disclosed display, because the aperture needs to move around during a multiplexing cycle. Thus, even if it were said that a parallax barrier display comprises a scanning of the liquid crystal cells, because the liquid crystal cells are turned on and off between frames, there is no scanning sequence, because the slits and barriers are static and not to move during a generation of an image by the image generating layer.

[0022] Fast operating liquid crystal cells are not necessary in a parallax barrier display, because the liquid crystal cells are alternated between only a few states during a multiplexing cycle, typically two, e.g. as mentioned above the liquid crystal cells define slit or barriers and this can be achieved with liquid crystal cells used in traditional 2D displays operating at 60 frames per second.

[0023] Summary of US20050219693

[0024] US20050219693 discloses a specific example of a parallax barrier display. In this specific example the barrier / aperture moves in front of an image generating layer.

[0025] For each position of the aperture, the image generating layer generates a perspective of a scene, e.g. for each position is generated a new image - each image showing a perspective of a scene. Thus, a full image is created for each position of the aperture, e.g. all pixels in the image generating layer are scanned / updated. Such a display can show a hologram, but the brightness will be low, because it is still a parallax effect that is used to achieve the depth perception.

[0026] For a “frame” which is 1 / 20 of a second in US20050219693 the aperture has been at 18 positions (for a non blinking perception for an observer a frame duration should be 1 / 60 or more of a second, but US20050219693 cannot achieve that - the present disclosure can). At each position the display screen generates a whole image. Each image is a perspective of a scene. Thus, 18 images are generated in each time window of 1 / 20 of a second. A normal display generates 1 image, and the present disclosure (the hybrid scan display) generates one image per active viewing zone. A suitable number of aperture positions in the present disclosure would be 32. If US20050219693 had 32 aperture positions the US20050219693 display would have to generate 32 images per 1 / 60 of a second. That is not realistic. At present it is not even clear if it is realistic to generate 18 images per 1 / 60 of a second in a mass produced display. It is so fast that such a display cannot realistically be mass produced because the specification for the control electronics is too high, e.g. components used for mass production are not that fast. However, the present disclosure can account for that by showing the same right eye image to each right eye and the same left eye image to each left eye. This is not possible in US20050219693.

[0027] When an observer looks at the US20050219693 display the right eye of the observer will see one part of the scene (specific perspective image generated at that aperture position) and the left eye will see another part of the scene from the angle of that aperture position - just as if the observer looked through an aperture with the real world on the opposite side of the aperture. This is simple ray tracing - the aperture will focus different parts of the image on the two eyes. As the aperture has moved through all aperture positions the observers brain integrates the 18 parts for each eye which creates the 3D perception.

[0028] This means that the US20050219693 display cannot be used to watch a 3D movie, such as Avatar or any other 3D movie, because 3D movies do not have recordings of 18 perspectives for each frame. 3D movies only have a right eye image and a left eye image.

[0029] The US20050219693 display can also not be used as a multiview display, e.g. a display where one observer watches one movie and another observer watches another movie.

[0030] Furthermore, the brightness will decrease by a factor of 18 or more. This is also not something that happens with the present invention.

[0031] Compared to this the disclosed display generates an image for each active viewing zone, e.g. a right eye image for a right eye and a left eye image for a left eye for example. Or a first image to an active viewing zone to the right of the display and a second image to an active viewing zone to the left of the display (images to a passenger and a chauffeur in a car for example). The images are not generated sequentially as in US20050219693, but all the images are split in parts and the parts are placed in a sequence with a part of one image being followed by a part of another image in the sequence. An analogy is that in the present disclosure it could be said that the different images are generated in parallel.

[0032] The disclosed display directs the light specifically to the active viewing zones, and nothing can be seen in the non active viewing zones, because no light is generated for the non active viewing zones - the display is not capable of directing light to all viewing zones.

[0033] Summary of the disclosed display

[0034] The disclosed display has different components and operates in a different way than lenticular displays and parallax barrier displays.

[0035] In summary, the disclosed display comprises the following two key components:

[0036] 1) A layer comprising light emitters arranged in columns (LED columns for example - there may be only one light emitter per column) where each light emitter may be driven with a high current in a low duty cycle for a very high peak pulse brightness.

[0037] 2) A layer with modulators, such as liquid crystal cells, having fast response times (such as ferro-electric liquid crystal cells).

[0038] Thus, it is a combination of a microLED panel and a liquid crystal display panel, e.g. a microLED FLCD display - a backplane constituted by a plurality of LEDs (one per pixel) and a frontplane with the (fast) liquid crystals.

[0039] And when it comes to the control of the disclosed display, the disclosed display has two key features, e.g. the controller is arranged for controlling the display such that:

[0040] A) Each liquid crystal cell is open only a small fraction of a multiplexing cycle, such as less than or equal to 20 % or 12.5 % or 10 % or 5 % of the multiplexing cycle excluding blanking period, e.g. one liquid crystal cell is open at a time during each step in the scanning sequence of the liquid crystal cells creating an effect of a moving aperture during the multiplexing cycle. B) Each image is divided in a number of parts, and the sequence of image parts for each image are interleaved resulting in an interleaved sequence. Thus, while one liquid crystal cell is open in a time interval (Tc) a number of steps of the multiplexing cycle takes place such that a number of LED columns are scanned non-consecutively, e.g. a plurality of non-neighbouring LED columns are selected one by one in each step for generating a light pattern, e.g. for emitting light.

[0041] For example, with two active viewing zones, such as a right eye zone and a left eye zone, two images are to be displayed, a right eye image R and a left eye image L. With five liquid crystals each image is divided into five parts: R1 , R2, R3, R4, R5, L1 , L2, L3 L4 and L5. The interleaved sequence IS will then be:

[0042] IS: R1 , L1 , R2, L2, R3, L3, R4, L4, R5, L5.

[0043] This example has a very rough horizontal resolution, e.g. only 5 pixels. The resolution may be increased either with more crystals or with an additional module. If each module has five crystals the horizontal resolution is now ten pixels and two interleaved sequences (IS) run in parallel:

[0044] IS1 : R1 , L1 , R2, L2, R3, L3, R4, L4, R5, L5

[0045] IS2: R6, L6, R7, L7, R8, L8, R9, L9, R10, L10

[0046] The two sequences could also be:

[0047] IS1 : R1 , L1 , R3, L3, R5, L5, R7, L7, R9, L9

[0048] IS2: R2, L2, R4, L4, R6, L6, R8, L8, R10, L10

[0049] As is evident it is important that a part of an image for one active viewing zone is followed by a part of an image for another active viewing zone. For a few number of viewing zones the sequence may have two or three or maybe four parts from the same image following each other in the sequence before one or more parts from another image such as:

[0050] IS: R1, R2, L1 , L2, R3, R4, L3, L4, R5, R5 This will require that the moving aperture moves “two” times, e.g. each crystal needs to be opened / scanned the same number of times as parts from the same image follow each other in the sequence.

[0051] Not all LED columns are scanned for emitting light, only the ones that are needed for directing light to a (active) viewing zone, e.g. as mentioned, a viewing zone / region is defined as an active viewing zone when there is an observing eye in that viewing zone. Light is not emitted to non-active viewing zones (except if the display is to operate in a multiview mode or display 2D content to non eye tracked observers). For each active viewing zone there is a column (depending on the selected liquid crystal cell that is open) that together with the aperture results in a vertical image pattern being visible in the active viewing zone. Each image pattern corresponding to an image part (and not a whole image).

[0052] The number of times columns are “selected” (from the plurality of columns) is a function of the number of liquid crystal cells and the number of viewing zones (equals the number of cells multiplied with the number of active viewing zones. For example, with four active viewing zones and 32 cells a total of 128 light flashes is generated in a multiplexing cycle.

[0053] The three terms scanned / updated / addressed which are used in the industry are interchangeably used in the disclosure unless specifically explained otherwise, and the term “selecting” is to be understood as a general term for any of these three terms.

[0054] Thus, it is not the FLCD-microLED combination by itself that gives the effect it is the addition of a special scanning sequence of both the fast liquid crystals and the LEDs that achieves a 3D perception with look around effect for several observers, e.g. if an observer moves the display is able to generate a new perspective that corresponds to the new position (it is individual content to all observers). This may also reduce motion sickness. It is the first solution that achieves this in HD quality and without using lenses.

[0055] The solution may be termed a hybrid scan display, because both the backplane and the frontplane are scanned in a special sequence.

[0056] In addition to the above solution the present disclosure also discloses the following alternative solutions: A scanning of the light emitters that is independent of observer position. This may be called a sliding window solution. For such a solution the display can only generate two images per multiplexing cycle. Thus, all right eyes may receive a right eye image and all left eyes may receive a left eye image. Therefore, it is not possible to provide individual contents to the different users.

[0057] Both the hybrid scan solution and the sliding window solution may be provided as a backlight for a LCD panel. This may be called a backlight solution. For the backlight solution the microLED panel may be replaced with vertical light guides.

[0058] In the backlight solution the LCD panel may either be placed in front of the light modulators (FLCDs) or it may be placed between the light emitters and the light modulators.

[0059] The present disclosure also proposes schemes for DC balancing the light modulators and the LCD panel as well for the backlight solutions.

[0060] There is also disclosed a solution for using the disclosed display in a vehicle.

[0061] “LED” panel configuration

[0062] The light emitters may be arranged in what in the display industry is known as a backplane. It may be a printboard comprising light emitters, preferably a microLED panel in HD resolution.

[0063] “FLCD panel” configuration

[0064] The liquid crystal cells constitute a (spatial) light modulator layer arranged as a plurality of vertically elongated light valve columns. Each liquid crystal cell is arranged as an aperture with respect to the light emitters. This means that the aperture has an optical power / focusing effect and light is focused by the aperture, and the aperture is to be fully illuminated horizontally.

[0065] The liquid crystals / molecules of the layer of modulators may be chiral smectic liquid crystals. They may be sandwiched between two pieces of glass or other transparent material, such as transparent plastic, for example glass sheets / plates. The distance between the two pieces of glass or other transparent material may be less than 2.2 micrometer (1 x 10A-6 m), such as less than 2 micrometer or less than 1.8 micrometer.

[0066] Spacers

[0067] The distance between the two components of the display, e.g. the light emitters (arranged in the backplane) and the light modulators (arranged in the frontplane) may be maintained by spacers, such as spacer balls, e.g. spacers shaped like a ball, e.g. having a round shape.

[0068] The distance may be greater than 1 cm, such as greater than 1.5 cm or in the range 2 mm to 60 mm such as 2 mm to 40 mm.

[0069] The spacers may be arranged in an irregular grid, such as random or psedu random arrangement, e.g. the spacers may be arranged without any periodicity, or at least a large period. For example, if one group of spacers has a pattern such a pattern is to be repeated with a distance of at least 2 % or 5 % or 10 % of the diagonal of the display. Thus, at least one group of spacers are arranged irregularly such that there is no periodicity within that group, e.g. the grid in which the spacers of the group are arranged does not have a transformation that allows to transform that grid into a rectangular grid. There may be a spacer at each node in the grid.

[0070] Modules

[0071] The light emitters and liquid crystal cells may be divided into logical modules, which may be controlled in parallel, e.g. the light emitters divided into in a first set of logical modules constituting a set of light emitter modules, and the light modulators divided into in a second set of logical modules constituting aperture modules.

[0072] In the following when referring to the term “module” is meant the collection of a light emitter module and aperture module together constituting a “module”, e.g. a module comprises an aperture module in front of a light emitter module.

[0073] A small disclosed display (size of about 2 inches) may comprise only one module. Fast response times

[0074] Both the light emitters and the liquid crystal cell are thus to have fast response times (for a desired number of observers, e.g. more than two observers observing 3D content).

[0075] The very fast response times may be achieved by using a mechanically stable very fast ferroelectric liquid crystal light modulator combined with even faster light emitting diodes, operated in a multiplexing cycle where the response time requirement for the light modulator is minimized and the update frequency made possible by having a higher update frequency of the LED columns than of the liquid crystal cells. This may be achieved by the above-described key features.

[0076] The reason why the required scan rate or speed can be achieved is that only the needed LED columns for the active viewing zones are updated with pixel values - meaning that the liquid crystal cells need to be fast as well in order to create the moving aperture in a multiplexing cycle.

[0077] Low number of open liquid crystal cells

[0078] During a multiplexing cycle all liquid crystal cells are opened at least one time (outside of a blanking period, cf. the description below), and each liquid crystal cell is open only a small fraction of a multiplexing cycle, e.g. one liquid crystal cell is open at a time during each step in the multiplexing cycle (it may be that one liquid crystal cell is not entirely closed before the next starts to open).

[0079] Thus, the scanning sequence of the liquid crystal cells creates an effect of an aperture moving across the LED columns during a multiplexing cycle.

[0080] Moving aperture

[0081] The term “moving aperture” is not to be understood literally in that there is something that physically moves. It is a new liquid crystal cell that has been open for light transmission at each step in the scan of the plurality of liquid crystal cells, but since the liquid crystal cells has different positions, the effect will be that during a multiplexing cycle an aperture has occupied each position, and it therefore looks like it has moved. Thus, behind each open liquid crystal cell is a large number of LED columns, and the (single) open liquid crystal cell (of a module) functions as an aperture focusing the LED columns on the observers one column at a time for each viewing zone by “moving” the aperture one position at a time.

[0082] To summarize, a parallax barrier display has a high number of liquid crystal cells being open (being in a light transmitting state) and the disclosed display has a low number of liquid crystal cells being open, e.g. the opposite of a parallax barrier display. The advantage is that there is a large number of pixels behind each aperture for zero unwanted rays in a large, central viewing zone and further greatly reduced number of unwanted rays in peripheral viewing zones, hence allowing a large number of observers without or with very little artifacts.

[0083] Pulsed LEDs

[0084] There is a disadvantage of this principle behind the disclosed display though, because the low number of open liquid crystal cells reduces the brightness of the display.

[0085] To solve that problem the disclosed display may use pulsed light sources with a high peak pulse optical power.

[0086] Since the disclosed display has a high multiplexing ratio and corresponding multiplexing frequency conditions for operating light sources, such as LED’s, in pulsed mode can be met, e.g. peak pulse duration (Tied) is below a certain threshold (such as 100 micro seconds) and multiplexing ratio is above a certain threshold (such as 30 or 100 or 200). The peak pulse brightness may be for example 5-50 times higher than a continuous brightness for certain types of LEDs, solving the brightness problem.

[0087] An LED column may be flashed in a pulse of width Tied shorter than a duration of the light valve column open time window (Tc) divided by a number of active viewing zones (viewing zones comprising an observing eye).

[0088] For example, Tc may be 260 microseconds and a number of viewing zones may be 10 hence Tied = 26 microseconds. During such a short pulse the current through an LED may be very high, for example between 100mA and 1000mA, which we may refer to as a peak pulse current (Ip).

[0089] The image observed by an observer is time integrated on the retina of the observer’s eye and it’s maximum brightness may be a function of the maximum peak pulse brightness, the pulse width Tied and a number of pulses per duty cycle. The pulse width of an LED and the number of pulses per duty cycle may be defined as described above for the general operation of the display, hence may be restricted.

[0090] The pulsing of the LEDs is relevant for both organic (OLED) as well as inorganic LEDs, such as microLEDs.

[0091] In other words, pulsed operation may be defined as, in an interval in which an aperture is open, operating an LED outside of a condition suitable for sustained operation and, after that interval, including a recovery interval, in which the LED may recover. In the present disclosure such operation may be synchronized with the scanning of apertures for achieving more brightness and / or better LED performance, including longer lifetime. An aperture is a liquid crystal cell / light modulator that is open for light transmission, e.g. light transmitted from behind the cell is transmitted through the cell and is visible to an observer.

[0092] Example of time intervals

[0093] For example, the disclosed display may have a frame rate of 60 frames per second resulting in a duty cycle duration of a multiplexing cycle of (Tm) = 1000 / 60 milli seconds = 16.7 ms.

[0094] A 50 % blanking period may be used for maintaining a DC balance of the liquid crystal cells. Alternatively, DC balance may be maintained through voltage time product balancing.

[0095] The time interval in which a liquid crystal cell is open (either with or without transition time) is in the present disclosure referred to as (Tc).

[0096] With (Nc) = 32 liquid crystal cells and (Nz) = ten viewing zones a liquid crystal cell may then be open in a time interval (Tm) / (Nc) * 0.5 = 16.7 / 32 * 0.5 = 0.26 ms including transition time (the time it takes for a liquid crystal cell to transit from a fully closed state to an fully open state).

[0097] If it is assumed there is a 0.05 ms transition time for turning a liquid crystal cell on (open) and off (closed) a liquid crystal cell is (fully) open in a time interval 0.26 - 2 x 0.05 = 0.16 ms.

[0098] For optimization, the next liquid crystal cell in the sequence can begin to open some time before the previous has closed, for example this time can be a function of the transition time (for example be equal to), e.g. the next liquid crystal cell can begin to open / be addressed / scanned 0.05 ms before the previous liquid crystal cell in the scanning sequence closes.

[0099] The time interval in which a liquid crystal cell is open including transition time may be used to define the (maximum) pulse width of an LED. Thus, as an example of a maximum pulse duration / width the LED pulse duration including pre-charge is then (Tied) = (Tc) I (Nz) = 0.16 ms / 10 = 16 micro second (us). A maximum pulse duration may correspond to a maximum brightness when using pulse width modulation, e.g. if the brightness value of a pixel is 50 % of the maximum brightness, the pulse duration is 50 % of the maximum pulse duration.

[0100] The LED duty cycle is then (Tied) I (Tm) =16 us I 16.7 ms = 0.0958 % (at maximum brightness).

[0101] A duty cycle is defined as the ratio of time a load or circuit is ON compared to the total time, e.g. Ton / ( Ton+ Toff).

[0102] Multiplexing cycle

[0103] The display uses a so called multiplexing scheme for generating the images to each active viewing zone, e.g. it is a multiplexed display.

[0104] For such a display sub-units of the display (typically, rows or columns for a dot matrix display or individual characters for a character oriented display, occasionally individual display elements) are multiplexed, that is, driven one at a time, but the high switching frequency and the persistence of vision combine to make the viewer believe the entire display is continuously active.

[0105] Said in other words, in a multiplexing scheme each image is divided into parts, e.g. a sequence of image parts / elements is made, and the display then generates the parts one after the other one step at a time in the sequence. This is referred to as a multiplexing cycle.

[0106] Specifically, in each step of the multiplexing cycle pixel values are provided in data lines connected to the LEDs in each column, and a specific column is selected by a “select signal” on a select line.

[0107] Thus, in a specific step an LED column is selected such that it emits a light pattern according to the pixel values provided by the data lines. The sequence of the multiplexing cycle can be said to be the order of the columns that are to be scanned.

[0108] Interleaved sequence

[0109] For the disclosed display the sequences of image parts for each image to be displayed in each viewing zone are preferably interleaved resulting in an interleaved sequence, e.g. the image parts of the different images are inserted in between each other - each element of the interleaved sequence is an image part (a single column of pixel values).

[0110] The interleaved sequence alternates between image parts from different images, e.g. the interleaved sequence does not have two consecutively (one after another without interuption) elements from the same image.

[0111] For example, for two observers the resulting interleaved sequence has as first element a first part of a first image for a right eye of observer 1. The second element is a first part of a second image for a left eye of observer 1 . The third element is a first part of a third image for a right eye of observer 2. The fourth element is a first part of a fourth image for a left eye of observer 2. These first four elements correspond to the first four steps in the multiplexing cycle, e.g. in the first four steps the four image parts are generated, e.g. the first image part of each of the four images. The elements of the interleaved sequence does not have to be in any specific order. As will be explained later all image parts can be generated in parallel or they can be generated in a random order. The fifth element of the interleaved sequence is a second part of the first image, and the sixth element is a second part of the second image and so forth.

[0112] The first parts of each image are generated when a first liquid crystal cell open, and when the first parts has been generated / displayed the first liquid crystal cell is closed and a second liquid crystal cell is opened, and the second parts of each image may be generated / displayed.

[0113] Single image part

[0114] For the disclosed display each image is divided into a number of parts, e.g. a part for each (single) pixel column of the image.

[0115] This single image part of an image is then generated / displayed when a liquid crystal cell is in the light transmitting state, and the LED column emitting a light pattern defined by a respective single image part in each step of the multiplexing cycle - a plurality of single images parts are generated (one for each image) when a specific liquid crystal cell is open.

[0116] Since there may be a number of modules as mentioned below there may be displayed one image part per module. So if there are for example 60 modules there will be displayed 60 parts of an image in total at each step in the multiplexing cycle.

[0117] Number of modules

[0118] If the images to be displayed have a horizontal resolution of 1920 (pixel columns), which is a typical resolution in the industry, and a preferred number of liquid crystal cells is 32 the number of modules of the disclosed display is 1920 / 32 = 60.

[0119] Each module is then responsible for displaying 1 / 60 of an image.

[0120] At each step of the multiplexing cycle are emitted 32 light patterns for an active viewing zone. Thus, the 1 / 60 of an image that a module is responsible for is divided into 32 parts, e.g. resulting in 32 * 60 = 1920 image parts. At a given time, e.g. on average, 60 parts are displayed more or less in parallel, e.g. one part per module. To summarize, 60 apertures will move across the aperture layer (one aperture per module). Said in other words, at the beginning of a multiplexing cycle for generating one or more images to a number of observing eyes / active viewing regions a number of liquid crystal cells are set to be open - thereby defining a number of apertures at the beginning of the multiplexing cycle. The light modulators of the display are controlled such that each aperture have a number of positions during the multiplexing cycle - the number of positions of each aperture is the horizontal resolution of the display divided by the number of modules (or not more different than 5 % of the horizontal resolution of the display divided by the number of modules.

[0121] Multiplexing ratio

[0122] The multiplexing ratio is the number of steps in the multiplexing cycle, and each step in the multiplexing cycle lasts a time interval of (Tm) as mentioned, e.g. it is the length of the sequence excluding a blanking period.

[0123] Using the same example of 32 liquid crystal cells and 10 active viewing zones, the multiplexing ratio is 32 * 10 = 320.

[0124] Sub-sequences

[0125] One thing that is desired when it comes to the interleaved sequence is that it comprises “sub-sequences” defining the scanning sequence of the LED columns that are to be scanned / updated with pixel values and emit a light pattern when a liquid crystal cell is open.

[0126] Specifically, it is desired that a sub-sequence only comprises image parts for different images such that an image part for each image is generated during a sub-sequence scanning (with generated is meant emitting a light pattern transmitted through the aperture and observed by an eye in an active viewing zone).

[0127] Thus, a first sub-sequence has only elements that are image parts from each of the images - there is no sub sequence that has two elements that each are an image part from the same image. A sub-sequence of the multiplexing cycle is a function of the liquid crystal cell being open (at a step in the scan sequence of the liquid crystal cells) and the active viewing zones.

[0128] Such sequences and dependency do not exist in a parallax barrier display where the scan sequence of the image generating layer is independent of the control or scanning sequence of the liquid crystal cells, e.g. in a parallax barrier display one image at a time is generated or at the same time depending on the variant. However, doing that in the disclosed display would not work, because this would require all LED columns to be scanned during the time interval (Tc), e.g. during the time a liquid crystal cell is open. Instead, only LED columns for active viewing zones are selected / scanned during the time a liquid crystal cell is open.

[0129] Avoiding “jumping” liquid crystal cells

[0130] The reason for this is to have to avoid to “jump” to another liquid crystal cell and open that during a sub-sequence, e.g. as mentioned it is desired that each liquid crystal cell is only open once - if not the speed of the liquid crystal cells would have to be increased.

[0131] There can be an exception to this, e.g. it cannot be ruled out that an interleaved sequence is made by the controller such that there is a jump back and forth to the same liquid crystal cell such that the same liquid crystal cell has been open more than once during the multiplexing cycle. This can be due to avoid view crash for example. This is also the reason that it is desired that each liquid crystal cell being open (in the light transmitting state) less than a percentage (such as less than 12.5 %) of the duration of the multiplexing cycle.

[0132] Pause between scans of the same LED column

[0133] The peak pulse current (Ip) defines a peak pulse brightness of an LED, and it is therefore desirable to maximize the peak pulse current.

[0134] The maximum peak pulse current may be defined by characteristics of an LED, such as a maximum allowable junction temperate, and / or thermal resistance, and / or of a dark interval / pause following a pulse before the (same) LED is pulsed (flashed) again. The longer the dark interval, the higher the maximum peak pulse brightness. However, the order of flashing LED columns (order in a sub-sequence) during a light valve time window (Tc) may as mentioned be selected in many different ways.

[0135] The order of scanning light valve columns (liquid crystal cells) may also be selected in many different ways without affecting the perceived images by observers.

[0136] Hence the dark interval between pulses of a specific LED may be maximized meaning that the LED’s maximum radiation / light emission may be maximized by selecting the order of flashing / scanned LED columns and / or the order of scanning the light valves.

[0137] Specifically, the display defines a first sub-sequence determining the order of LED columns (or set of neighboring LED columns) to be scanned when a first liquid crystal cell being is open, e.g. the timely order in which the active viewing zones are to receive image parts.

[0138] For the subsequent liquid crystal cell (when it opens) is defined a second sub-sequence.

[0139] It may be that the two sub-sequences define that the same LED column is to be flashed when the first liquid crystal cell is open and when the subsequent liquid crystal cell is open.

[0140] It is to be avoided that this same LED column is flashed two times in a row - or that it is flashed with a pause (between flashes) that is too small.

[0141] This can be avoided by defining for example the second sub-sequence as a function of the first sub-sequence or the other way around.

[0142] For example, if a first LED column is flashed as the last LED column in the first sequence it should not be flashed as the first LED column in the second sub-sequence - a number (Nmin) of other LED columns should be flashed in between a particular LED column is flashed such that it has a pause.

[0143] Nmin may for example be at least one. Alternatively, Nmin may be between 1 or a number equal the number of viewing zones comprising an observing eye minus 1. For example if the number of observers is 5 there may be 10 viewing zones comprising observing eyes hence Nmin may be between 1 and 9.

[0144] It may be that there has to be some balance between how long a pause can be and view crashes, e.g. for a specific sub-sequence defined to have a long pause that specific sub-sequence will introduce a view crash.

[0145] Thus, the second sub-sequence may be a function of maximizing a pause and minimizing view crash.

[0146] In addition to or as an alternative, the scan sequence of light valve columns may be selected to increase Nmin - it may be that for example it is not possible to change the second sub-sequence without introducing a view crash. Changing the scan sequence of liquid crystal cells may achieve that there will be a pause and minimize or avoid view crash.

[0147] For example a light valve scanning sequence may be selected so a first light valve is opened during which LED columns are flashed (according to a first sub-sequence) and after that a second light valve is opened during which LED columns are flashed and the first and the second light valve may be selected so there are no LED column being scanned twice when these two liquid crystal cells are open.

[0148] Further, the scan sequence may be selected so a third light valve is opened during which LED columns are flashed. The third light valve selected, so there are no LED column being scanned twice when these three liquid crystal cells are open. This principle can be extended to a larger number of light valves being selected in a similar way, depending on the processing power of the controller.

[0149] A maximum Peak Pulse Current may be found experimentally for an LED which may be pulsed with a dark interval corresponding to Nmin of other LEDs being pulsed in between and where a Peak Pulse current is gradually increased until a critical (maximum) junction temperature for the LED is reached.

[0150] A specified maximum junction temperature may be provided by a manufacturer of the LED. Since it may be difficult to directly measure the junction temperature during a short peak pulse, this may be found indirectly by monitoring a voltage drop over the LED.

[0151] A correspondence function between voltage drop and junction temperature may be provided by an LED manufacturer or found experimentally by measuring junction temperature, for example with an infrared thermometer over longer periods of time than a peak pulse duration.

[0152] Frequency

[0153] The liquid crystal cells are scanned in a sequence at a frequency F(LC) being a function of the frame rate (how many images an observer is to view per second, e.g. frames per second, fps) and the number of liquid crystal cells, specifically the frame rate multiplied with the number of liquid crystals, for example with 60 frames per second and 32 liquid crystals this gives F(LC) = 60 x 32 = 1920 Hz.

[0154] The light emitters (LED columns) are scanned at a frequency F(LED) being a function of the scan frequency of the liquid crystal cells F(LC) and the number of viewing zones, specifically the scan frequency of the liquid crystal cells F(LC) multiplied with the number of viewing zones. If there are ten viewing zones this gives F(LED) = 1920 x 10 = 19200 Hz. It is understood that light emitters may further be modulated for brightness by pulse width and / or pulse amplitude modulation.

[0155] Fully illuminated aperture

[0156] As mentioned, it is preferred that LED columns are selected / scanned one by one in each step of the multiplexing cycle for generating a light pattern, e.g. for emitting light. Thus, one (a single) light pattern is generated at a time (passive matrix addressing) at each step.

[0157] With the term “single” is meant that the light pattern is for a single part of an image, e.g. a single image part is generated in each step of the multiplexing cycle by selecting a single column (or a set of neighbour columns emitting the same light pattern).

[0158] However, the special multiplexing cycle of the disclosed display introduces a problem of an irregular pixel pattern of the observed image. This problem may be solved by arranging the display such that the (single) light pattern that is generated in each step is delimited by liquid crystal cells adjacent the liquid crystal cell that is open such that only a part of the light rays of the (single) light pattern having a line of sight to the active viewing zone actually reaches this zone, e.g. had the neighboring liquid crystal cells not been closed more light rays (of the single light pattern) would have been received by the observer’s eye.

[0159] For example, it could be that the beam width (at a threshold such as at 3 dB) of the irradiated light is wider than the aperture (liquid crystal cell that is open) - it may only be slightly wider, but the beam width is not to be narrower than the aperture.

[0160] With a line of sight is meant a line from an observer's eye to a distant point (the LED column or diffuser in front of the LED column). Thus, part of what the observer would see if the neighboring liquid crystal cells, which has not been closed is blocked by these closed neighboring liquid crystal cells.

[0161] Ray tracing software may be used in the design phase of the display to determine if the outermost light rays to the left and to the right of a set of LED columns flashing light at a step in a scan sequence are delimited by the aperture. If this is the case the aperture is completely illuminated. It is not necessary in a parallax barrier display for each slit to be completely illuminated, because all slits for a viewing zone are open at the same which means that no black vertical stripes will appear.

[0162] Since there is darkness at each side of a LED column emitting light and only one column at a time emits light there would be formed a Moire pattern visible to the observer if there was no such delimitation, e.g. an observer would see a repeated pattern of dark stripes and this repetition (seen through apertures) gives rise to the Moire pattern. As a result, the image quality would be reduced.

[0163] US20050219693 discloses that the pixel width is defined by the image generating layer and contrary to the disclosed invention US20050219693 would have a Moire pattern if it were not for the fact that an entire image is generated at each step in US20050219693.

[0164] Liquid crystal cells define the position of pixels in the horizontal plane The above has the consequence that it is the liquid crystal cells that defines the horizontal pixel positions of the image observed in an active viewing zone, e.g. it is not the LED columns that defines the horizontal pixel position of the observed image - this is opposite to for example parallax barrier displays.

[0165] Set of columns

[0166] A specific solution for illuminating the aperture fully could be to select a set of neighboring LED columns in each step of the multiplexing cycle making the light pattern “wider”. The set may comprise for example two neighboring LED columns. In the example in the drawings three are illustrated.

[0167] Specifically, the set of columns are updated with the same pixel data values at each data line and the switch for each column in the set of columns are then selected and switched on thereby establishing a parallel connection of the LEDs in the set of columns, and the LEDs are driven at a current which corresponds to the normal driving current multiplied with the number of columns in the set.

[0168] A parallel connection of LEDs is normally a problem since LEDs do normally not have the same forward voltage, but in this case each column in the set is to emit the same light pattern and the LEDs are driven at high voltages.

[0169] A set of columns may comprise between 1 and 10 columns, preferably 2 or 3 or 4 columns.

[0170] Diffuser

[0171] Another specific solution for illuminating the aperture fully could be to have a diffuser for diffusing light horizontally and placing it between the LED layer and the liquid crystal cells, e.g. the diffuser may be a horizontal diffuser - diffusing more light in the horizontal plane than in a vertical plane.

[0172] If a diffuser were added to the display disclosed in US20050219693 the image would become blurred, because light from neighbouring pixel columns would be mixed by the diffuser. Both the solution with a set of columns and the diffuser may be combined.

[0173] Auto-stereoscopic display

[0174] A display operating as an auto-stereoscopic or multi-view display is per definition arranged to direct an image to a viewing zone in front of the display so that the image can only be observed in that specific viewing zone. In this way, a pair of two-dimensional images may be directed to an observer’s eyes who perceives a depth in the image, e.g. the display may direct a first image to the position of the right eye of the observer and direct a second image to the position of the left eye of the observer so that each eye sees a different image. In this case a first viewing zone corresponds to a first eye of the observer and a second viewing zone corresponds to a second eye of the observer.

[0175] Alternatively, in the situation when the display is functioning as a multi-view 2D display, a first observer at a first position in front of the display may see a first 2D image and a second observer at a second position in front of the display may see a second 2D image. In this case a first viewing zone may correspond to the face of the first observer and a second viewing zone may correspond to the face of the second observer.

[0176] A first aspect of the present disclosure is:

[0177] A hybrid scan display (for emitting light to a plurality of active viewing zones including a first active viewing zone and a second active viewing zone) comprising:

[0178] - a plurality of light emitters for emitting light,

[0179] - a plurality of liquid crystal cells, each liquid crystal cell arranged for switching between two states including a light transmitting state for transmitting light from said plurality of light emitters or a light shielding state for shielding light from said plurality of light emitters.

[0180] A second aspect of the present disclosure is:

[0181] A method for emitting light to a plurality of active viewing zones including a first active viewing zone and a second active viewing zone by means of a hybrid scan display, said hybrid scan display including

[0182] - a plurality of light emitters for emitting light,

[0183] - a plurality of liquid crystal cells, each liquid crystal cell arranged for switching between two states including a light transmitting state for transmitting light from said plurality of light emitters or a light shielding state for shielding light from said plurality of light emitters, said method comprising providing said hybrid scan display and emitting light by means of said light emitters and switching said liquid crystal cells for directing light to said plurality of active viewing zones.

[0184] % backlight

[0185] A third aspect of the present disclosure is:

[0186] A display comprising:

[0187] - a LCD panel for generating a first image and a second image during a multiplexing cycle, and

[0188] - a backlight for emitting light towards said LCD panel, said backlight including:

[0189] - a plurality of light emitters,

[0190] - a plurality of light modulators between said plurality of light emitters and said LCD panel, each light modulator switching between two states including a light transmitting state for transmitting light from said plurality of light guides or a light shielding state for shielding light from said plurality of light guides,

[0191] - a controller arranged for scanning said plurality of liquid crystal cells such that each liquid crystal cell having been open once creating an effect of a moving aperture during said multiplexing cycle, said controller arranged for scanning said plurality of light emitters one after another in a sequence being a function of said moving aperture and alternating between said backlight emitting a first light flash visible at a first active viewing zone and a second light flash visible at a second active viewing zone, said LCD panel being synchronized with said backlight such that said LCD panel generates a part of said first image when said backlight emits said first light flash and said LCD panel generates a part of said second image when said backlight emits said second light flash.

[0192] % LEDs+FLCDs used as backlight for LCD and LEDs scanned from left to right (sliding window)

[0193] A fourth aspect of the present disclosure is: A display comprising:

[0194] - a plurality of light emitters for emitting light,

[0195] - a plurality of light modulators, such as ferro electric liquid crystal cells,

[0196] - a LCD panel for generating a first image in a first sequence during a multiplexing cycle, and a second image in a second sequence during said multiplexing cycle, said LCD panel arranged in front of said plurality of light emitters, and said plurality of light modulators arranged between said plurality of light emitters and said LCD panel,

[0197] - an observer tracker for tracking the position of one or more observers including a first observer and a second observer in front of said display,

[0198] - a controller arranged for controlling said plurality of light emitters independently from the position of said first observer and said second observer, said controller arranged for controlling said plurality of light modulators as a function of the position of said first observer and the position of said second observer such that a number of light modulators being in a light shielding state for shielding light from said plurality of light emitters from reaching the right eyes of said first observer and said second observer when said LCD panel generating said first image and a number of light modulators being in a light shielding state for shielding light from said plurality of light emitters from reaching the left eyes of said first observer and said second observer when said LCD panel generating said second image.

[0199] % Double FLCDs configuration

[0200] A fifth aspect of the present disclosure is:

[0201] A display comprising:

[0202] - a plurality of light emitters for emitting light,

[0203] - a first plurality of light modulators including a first light modulator arranged in a first layer,

[0204] - a second plurality of light modulators arranged in a second layer, each light modulator switching between two states including a light transmitting state for transmitting light from said plurality of light emitters or a light shielding state for shielding light from said plurality of light emitters, said first plurality of light modulators comprising chiral smectic liquid crystals sandwiched between a first transparent sheet and a second transparent sheet with a distance between said first transparent sheet and said second transparent sheet less than 2.2 micrometer, each light modulator of said second plurality of light modulators having a width greater than the width of said first light modulator, and / or at least two neighboring light modulators of said second plurality of light modulators being in said light transmitting state when said first light modulator being in said light transmitting state at a point in time during a multiplexing cycle.

[0205] % double FLCD DC balance

[0206] A sixth aspect of the present disclosure is:

[0207] A display comprising:

[0208] - a plurality of light emitters for emitting light,

[0209] - a first plurality of light modulators arranged in a first layer,

[0210] - a second plurality of light modulators arranged in a second layer,

[0211] - a controller arranged for controlling said first plurality of light modulators including a first light modulator such that said first light modulator being in a light transmitting state at a step in a multiplexing cycle while said first plurality of light modulators comprising a first set of light modulators on each side of said first light modulator being in a light shielding state, and aligned with light modulators of said second plurality of light modulators being in a light shielding state, and said controller arranged for controlling said first plurality of light modulators such that said first plurality of light modulators comprising a second set of light modulators at said step, said second set of light modulators being in a light shielding state, and aligned with light modulators of said second plurality of light modulators being in a light transmitting state.

[0212] % distance between bands

[0213] A seventh aspect of the present disclosure is:

[0214] A display comprising:

[0215] - a plurality of light emitters for emitting light,

[0216] - a plurality of light modulators,

[0217] - a LCD panel arranged for alternating between generating an image for a right eye of an observer and a left eye for said observer, said LCD panel arranged in front of said plurality of light emitters, said plurality of light modulators arranged between said plurality of light emitters and said LCD panel, said LCD panel comprising a plurality of columns of liquid crystal cells,

[0218] - a controller arranged for controlling said plurality of columns of liquid crystal cells such that at a step in a multiplexing cycle at least two neighboring columns being updated with the same pixel values such that each of said at least two neighboring columns generating the same column of an image, and said controller arranged for controlling said plurality of columns of liquid crystal cells such that a first and a second column of said plurality of columns of liquid crystal cells generating a last image column of a first image generated in said multiplexing cycle, and a third and fourth column of said plurality of columns of liquid crystal cells generating a first image column of a second image generated in said multiplexing cycle, said LCD panel comprising at least two columns of liquid crystal cells between said first column and said third column.

[0219] % calibration

[0220] A eight aspect of the present disclosure is:

[0221] A method for calibrating a display, said method comprising: providing said display including a controller, a plurality of light modulators including a first light modulator, a plurality of light emitters including a first light emitter and a plurality of light sensors including a first light sensor, said first light sensor arranged above or below said first light emitter when said display being positioned in a stand or wall mounted, emitting light towards said display from a position in front of said display, scanning said first light modulator such that said first light modulator being in a light transmitting state, when said light being detected by said first light sensor said first light emitter being selected by said controller such that when said controller scanning said first light emitter said first light emitter emitting light towards said position.

[0222] % No diffuser

[0223] A ninth aspect of the present disclosure is: A display comprising: a plurality of light emitters for emitting light, a plurality of light modulators, a controller arranged for controlling said plurality of light modulators such that a number of neighboring light modulators being in a light transmitting state for defining an aperture at a first position at a step in multiplexing cycle, and said controller arranged for controlling said plurality of light emitters such that a first light emitter at a second position emits a light pattern of a pixel column in an image defined by said second position, said first position being different from said second position, said controller arranged for scanning said plurality of light modulators such that at a first step in a multiplexing cycle a first set of neighbouring light modulators being in a light transmitting state, and at a second step in the multiplexing cycle a second set of neighbouring light modulators being in a light transmitting state, said first set of neighbouring light modulators including a first light modulator, and said second set of neighbouring light modulators including said first light modulator.

[0224] With the term “generating” is meant producing or creating, e.g. with generating an image is meant that the image pattern of the image file is produced such that it may become visible to an observer (when backlight is applied in the case of LCD). And generating light means that light is produced such that light is emitted.

[0225] With “two states” is meant that the cells are preferably binary operated, e.g. with binary “mode” is meant that the liquid crystal cells exclusively have the two mentioned states (light transmitting state and a light shielding state). The cells are not operated in a grey scale mode, e.g. having a plurality of states with different grey values (light transmission). Said in other words, a cell is either 100 % open or 100 % closed - or as close to 100 % as possible depending on manufacturing tolerances (liquid crystals are known to have some light transmission even when being closed).

[0226] As mentioned the display may comprise a plurality of modules where each module is arranged as above, e.g. a plurality of light emitters for emitting light, said plurality of light emitters preferably arranged in columns, and a plurality of liquid crystal cells, each liquid crystal cell switching between two states including a light transmit-ting state for transmitting light from said plurality of light emitters or a light shielding state for shielding light from said plurality of light emitters.

[0227] The display may also only have one (a single module), but that would be a small display (such as two inches) or a display with low resolution.

[0228] The modules may be controlled in parallel by a controller. There may be a dependency between the control of two or more modules.

[0229] Each module may be controlled according to the below.

[0230] The controller may scan the plurality of liquid crystal cells in a sequence such that each liquid crystal cell having been open once creating an effect of a moving aperture during a multiplexing cycle.

[0231] The controller may be arranged for scanning the columns and the plurality of liquid crystal cells during the multiplexing cycle for displaying a plurality of images, each image divided into a sequence of image parts, each image part constituting a single column of pixels of said image, the plurality of sequences of image parts being interleaved into an interleaved sequence (defining the multiplexing ratio excluding a blanking period).

[0232] A single image part of an image is displayed when a liquid crystal cell is in the light transmitting state, and a respective column emits a light pattern defined by a respective single image part in each step in the multiplexing cycle. One single image part for each image to be displayed may be generated when a liquid crystal cell is open.

[0233] Said in other words the number of columns (of light emitters) that may be scanned when each liquid crystal cell is in the light transmitting state is greater than one and less than the (total) number of columns, e.g. preferably the number of columns ( = the length of a sub-sequence) is equal to the number of active viewing zones - not withstanding any “don’t care” columns that may be scanned for various reasons (a don’t care column is a column that generates a light pattern not visible in any of the active viewing zones).

[0234] The display may be arranged such that the light pattern emitted by a column is delimited by liquid crystal cells adjacent the moving aperture such that only a part of the light rays of the light pattern having a line of sight to the first active viewing zone reaching the first active viewing zone.

[0235] The controller may select vertical columns during a multiplexing cycle, a first vertical column selected as a function of a liquid crystal cell being in a light transmitting state and a first active viewing region, and a second vertical column selected as a function of said liquid crystal cell being in a light transmitting state and a second viewing region.

[0236] Each liquid crystal cell being in said light transmitting state less than 25 %, such as less than 20 % or 15 % or 10 % or 5 % of said multiplexing cycle.

[0237] The display may have a vertical pixel resolution being a function of the number of light emitters in a vertical column, and each individual pixel defined in width by the width of a liquid crystal cell.

[0238] The display may have a vertical pixel resolution being a function of the number of light emitters in a vertical column, and having a horizontal pixel resolution being a function of the number of liquid crystal cells of said plurality of liquid crystal cells (multiplied with the number of modules when the display has more than one module).

[0239] The display may have a vertical pixel resolution equal to the number of light emitters of a specific color in a vertical column.

[0240] The display may have a horizontal pixel resolution equal to the number of liquid crystal cells of said plurality of liquid crystal cells (multiplied with the number of modules when the display has more than one module).

[0241] A pixel of the display may be defined in width by the width of a liquid crystal cell and in height by the height of the light emitting area of a light emitter.

[0242] % Definition of a function

[0243] The term “function of” means that something is dependent on each other, e.g. x being a function of y means that x depends on y, e.g. has a value or state that depends in the value or state of y. It is the light emitters that are responsible for generating the light patterns that in the end leads to an image / contents that the display is to display to observers, e.g. a digital image is input to the display which then reads the pixel values of the image file and generates the contents based on that.

[0244] The light emitters may be light emitting diodes, such as microLEDs (array of microscopic LEDs forming the individual pixel elements), or OLED or an LCD + backlight. These are all known display types used to generate contents. In the present disclosure the terms “light emitters” and “light emitting diodes” may be interchanged.

[0245] The light emitters may be arranged in vertical columns. In the present disclosure this may be referred to as “LED columns” or “vertical columns of LEDs” or “light emitter columns”.

[0246] The term “liquid crystal cells may be interchanged with the terms “spatial light modulators” or “vertically elongated light valve columns” or “ferro-electric liquid crystal cells” or “LCD layer”. The liquid crystal cells may be arranged in a layer.

[0247] A light transmitting state may also be referred to as an open state, e.g. a liquid crystal cell being open (for light transmission).

[0248] The light emitting diodes by themselves or together with a diffuser may constitute a light spreader for emitting columns of light onto the LCD layer, e.g. one or more columns of light emitting diodes (set of LED columns) may be used to illuminate the LCD layer or alternatively a single LED column may illuminate a diffuser which in turns spreads the light onto the LCD layer.

[0249] The reason for this is that compared to a parallax barrier display it is important that the light is delimited by the aperture, e.g. the whole width of an aperture has to be illuminated in order for the aperture to have an optical power / focusing effect.

[0250] Said in other words the part of the LCD layer that is illuminated by the light spreader may be wider than the width of an aperture, e.g. the aperture blocks some of the light from the light spreader. In order to ensure this more than one column of LEDs may flash light at the same time (in the case no diffuser is used). Directional light emitters may be constituted by light emitting diodes with an optical element having an optical power (such as a lens) in front of each LED such that the display may have a vertical resolution of viewing zones, e.g. for each pixel there may be two directional light emitters, one for directing light downwards and one for directing light upwards. In this way, the display may direct an image towards observers sitting at the floor in front of the display and observers sitting on a couch in front of the display.

[0251] The plurality of liquid crystal cells could be said to constitute a moving lens, e.g. correspond to a single lens that is moved across the LEDs as explained above. This means that the whole aperture (liquid crystal cell in the light transmitting state) needs to be illuminated. Thus, it may be necessary to flash two adjacent LED columns (set of LED columns). It may also depend on the observer, e.g. if the observer is for example very close to the display relative to the distance between the vertical LED columns / arrays and the liquid crystal cells. This may also ensure an even light distribution independent of the observer distance to the display.

[0252] This is also different from how a parallax barrier display operates, because in that type of display the control of the barrier pattern is static, e.g. it has a fixed striped pattern, for example all even columns are open during the generation of a right eye image and all uneven columns being open during the generation of a left eye image.

[0253] If the light emitting diodes are OLEDs, the light emission is from a whole layer and not discrete emitters like inorganic LEDs. In this case, the radiation pattern may be controlled by how wide a part of the OLED layer is addressed in order to illuminate an aperture.

[0254] In any case, a diffuser may be placed between the light emitters and the liquid crystal cells. This may achieve that the light intensity of each liquid crystal cell has a (horizontal) brightness centroid substantially at the center of each liquid crystal cell when light being transmitted. Substantially meaning within production tolerances of a diffuser such that the position of the brightness centroid not deviating from center with more than 20 % relative to the width of a liquid crystal cell.

[0255] The (horizontal) brightness centroid is the “center of gravity” of the light transmitted through a ferro-electric liquid crystal cell in a horizontal plane. The (horizontal) brightness centroid may be defined as follows: at a given height of a ferro-electric liquid crystal cell, the brightness centroid is the weighted mean of all points across a ferro-electric liquid crystal cell (from left to right or vice versa) weighted by the specific light intensity of each point.

[0256] As an alternative to the diffuser, the display may be configured such that each liquid crystal cell having a light intensity that is a function of the position of the brightness centroid in a horizontal plane of the liquid crystal cell and two pixels of said digital image, e.g. firstly the position of the brightness centroid in a horizontal plane of the liquid crystal cell is determined, then it is determined where in the digital image this position corresponds to. If this position in the digital image is between two pixels, an “artificial” pixel value is determined by interpolating between these two pixel values, such as determining an average value between the two pixel values. The LED that is to emit light then emits a light intensity equal to the artificial pixel value.

[0257] For example, one pixel value may be one and the other pixel value may be 0. The artificial pixel value is then determined as 0.5.

[0258] When observing the display from a distance, this “re-sampling” or interpolation of the digital image compensates for the fact that the observer is at a position where the brightness centroid of a ferro-electric liquid crystal cell is not aligned with a pixel in the digital image. If this compensation was not carried out, the image would appear smudged. In praxis the diffuser does the same thing, e.g. the re-sampling may be done by an algorithm or by a diffuser.

[0259] In the case of inorganic or discrete LEDs, they may be placed at a distance horizontally such that two neighbouring LEDs are closer to each other than the width of the beam of light that one LED irradiates onto the liquid crystal cells, e.g. the beam width of the radiation pattern at the liquid crystal layer. Thus, the pitch between LED columns are smaller than the beam width of the radiation pattern at the liquid crystal layer. The beam width may be at 3 dB for example.

[0260] Liquid crystal cells are typically sandwiched between a pair of electrodes implemented as glass substrate layers. There may be a second layer / plurality of liquid crystal cells, e.g. two layers of liquid crystal cells arranged next to each other (one layer arranged between the LEDs and the other layer of liquid crystal cells). This may reduce light leaking through the liquid crystal cells, e.g. if light is leaked another observer than the intended observer may see artifacts on the display similar to cross talk between images.

[0261] During a multiplexing cycle (“cycle”), an image / frame has been generated to each viewing zone, for example a right eye image to a right eye viewing zone and a left eye image to a left eye viewing zone in the case of a single observer observing in 3D mode.

[0262] During a multiplexing cycle, all liquid crystal cells have been open, but only a percentage of the liquid crystal cells are open at a time e.g. only a percentage of the total number of liquid crystal cells are open at the same point in time. The percentage may be less than 25 %, such as less than 20 % or 15 % or 12.5 % or 10 % or 5 %. In the example below one liquid crystal cell is open at a time (1 out of 32 = 3.1 %), but it may be more than one (but less than the percentage) for taking into account that one liquid crystal cell may be open while another has initiated an opening.

[0263] During a multiplexing cycle the display is scanned / addressed such that one after the other of liquid crystal cells are opened, e.g. the liquid crystal cells are opened sequentially, e.g. in a sequence (from left to right or from right to left - another scan sequence may be used as long as all liquid crystal cells are scanned in the multiplexing cycle). Otherwise, the aperture would not move across the display.

[0264] Thus, a (light) signal is transmitted through each liquid crystal cell to an observer’s eye (for 3D) - one light signal for each liquid crystal cell that is scanned in the multiplexing cycle. For each eye the brain of the observer then multiplexes / integrates these signals to form a perceived image (which is why it is called multiplexing). If there are 32 liquid crystal cells the brain integrates 32 light patterns / signals. The left eye image and right eye image are then integrated by the brain to perceive a 3D image. This will be the case for all observers.

[0265] For each liquid crystal cell that is open are scanned a number of vertical columns of LEDs non-sequentially depending on the number of viewing zones (at least two viewing zones), e.g. one vertical column (of LEDs) is scanned / addressed per viewing zone when a respective ferro-electric liquid crystal cell is open. So the images for all viewing zones during a cycle may be generated by sequentially scanning the liquid crystal cells one by one and sequentially scanning a number of vertical columns per ferro-electric liquid crystal cell.

[0266] In an example of one observer observing 3D content, two vertical columns of LEDs are scanned each time one ferro-electric liquid crystal cell is scanned / addressed.

[0267] For a passive matrix addressing scheme the vertical columns are scanned one by one after each other.

[0268] In an active matrix addressing scheme the vertical columns may be scanned such that they stop emitting light substantially at the same time, e.g. there is a time window in which all the vertical columns emit light at the same time - they may be addressed one by one, but be driven by a driver circuit having a memory component such that a vertical column emit light for longer time than in a passive matrix addressing scheme and there is a time overlap in which all of them emit light.

[0269] If there are two observers observing different 3D content / images, four vertical columns of LEDs are scanned each time one ferro-electric liquid crystal cell is scanned / addressed. However, the same content may be displayed to each observer, in this way the vertical columns may be scanned in pairs, e.g. two vertical columns scanned at the same time for flashing light before moving on to the next two vertical columns.

[0270] The ferro-electric liquid crystal cells may be scanned independent from any viewing zone (or direction to viewing zone), e.g. the controller selects a ferro-electric liquid crystal cell to be scanned, and the column of LED to be scanned is then determined as a function of the selected ferro-electric liquid crystal cell and the viewing zone before the controller proceeds to the next ferro-electric liquid crystal cell that is to be scanned.

[0271] The vertical columns of LEDs are scanned dependent (as a function) of the number of viewing zones and the direction to each viewing zone. Which specific vertical columns that are to be scanned when a specific ferro-electric liquid crystal cell is open depends on the direction to the respective viewing zone. With scanning is meant addressing of relevant elements for generating the image for a respective viewing zone.

[0272] Both the ferro-electric liquid crystal cells and vertical columns of LEDs are scanned.

[0273] The ferro-electric liquid crystal cells are scanned in order to open one by one and the vertical columns of LED are scanned in order to flash light, e.g. during the scan.

[0274] The ferro-electric liquid crystal cells are addressed one after the other such that a ferroelectric liquid crystal cell that has been addressed opens for light transmission and the LEDs of a vertical column of LEDs are addressed one by one such that a vertical LED column that has been addressed emits light.

[0275] Thus, for an LED a scan results in a current being sent through the LED such that it emits light. For a LCD cell a scan results in a voltage being applied across the LCD cell and the liquid crystals in the cell orient according to the voltage. The LCD cell may comprise a driver for which the scan results in a value being written into the driver. It may be a pixel value in the case of an LCD panel in a backlight solution, or it may be a value for opening or closing an FLCD.

[0276] Eye tracking / observer tracking may be used to determine where in space the image is to be directed, e.g. the tracking may determine the direction to (or position of) a respective viewing zone. A camera may be used for the tracking.

[0277] A viewing zone may be the size of an eye, or it may be as large as the face of an observer. There may be only two viewing zones such that one viewing zone is to the right of the normal vector to the display surface and the other is to the left of the normal vector to the display surface, such a use case may for example be the infotainment screen in an automobile.

[0278] The vertical columns of LEds are flashed in order to have as high light intensity as possible, because the apertures / ferro-electric liquid crystal cells in front of the vertical columns of LEDs block some of the light thereby reducing the light intensity from the display. This is inevitable, because the liquid crystal cells are set up to function as apertures (and not slits). The flashing may also increase the number of viewing zones. The modules may also be called segments, and each module may be identical to the display according to the above aspect(s). As mentioned, it is not necessarily to be understood as physical segments, but logical segments, e.g. the controller controls the segments in parallel. This is explained further in connection with fig. 7.

[0279] For example, there may be four modules (next to each other) such that the image is split in four zones and each module being responsible for generating a fourth of the image.

[0280] The number of modules may also be defined by the controller (preferably as a function of active viewing zones / observers). For example, the number of observers and / or directions to observers may be such that the display is split in two “modules” arranged next to each other horizontally. This may increase the number of directions / viewing zones. The two modules may then be scanned in parallel such that overall two apertures are open at the same time - one in each module. The width of a module may be a function of the number of viewing zones.

[0281] An image pixel is defined in the width (horizontally) by the width of an aperture (ferroelectric liquid crystal cell) and in the height (vertically) by a light emitting diode in the vertical columns of LEDs (if a diffuser is between the two the height will be a bit higher).

[0282] Thus, the vertical resolution of the display is a function of the number of light emitters in a vertical column, e.g. the vertical resolution of the display is equal to the number of light emitters in a vertical column - notwithstanding subpixels if the display is a color display where the color is generated for example by three subpixels (red, green and blue). However, a color may also be generated by a stacked microLED.

[0283] The horizontal resolution equals the number of apertures. This is also contrary to a parallax barrier where the barriers does not determine the resolution of the display.

[0284] % Diffractive effects

[0285] The width of a light modulator define the pixel width of the display (horizontally). Thus, light passes through relatively narrow slits / apertures (compared to wavelength), which causes diffraction due to the wavelength nature of light.

[0286] In the following is disclosed why the diffraction of the disclosed display is minimal. It is well known that passing light through narrow slits will cause a diffraction of the light. The slits create a pattern of vertical bright and dark fringes. The two slit diffraction pattern is different from the single slit pattern. If the slits in the Hybrid Scan Display are narrow enough to cause diffractive effects, it is possible that unwanted side lobes could reach the eyes of viewers.

[0287] Two neighboring light modulators are considered, e.g. a two-slit situation. The interference for a two-slit example depends on the coherence length, Lc of the light. The coherence length of the light source is the distance over which the light wave maintains a predictable phase relationship. The coherence length Lc is given by:

[0288] Lc=AA2 / BW

[0289] Where A is the central wavelength of the emitted light (eg. 550nm) and BWis the spectral bandwidth of the LED (eg. 30nm). This gives a typical coherence length for a LED of 10 urn.

[0290] One must also consider the Coherence time (TC ). This is the time over which the light wave maintains a fixed phase relationship and is given by:

[0291] TC = Lc / c where Lc is the coherence length and c is the speed of light. With Lc= 10um, we get TC = 0.033 picoseconds.

[0292] This result suggests that if the time separation between the opening of two slits is a few picoseconds or more (which it will be), the light waves from the two slits will be incoherent with respect to each other, and no interference pattern will be observed by the observer. You would see only the sum of the individual diffraction patterns from each slit, single-slit diffractions having much smaller amplitude than interfering multi-slit diffraction.

[0293] In the following specific examples according to aspects of the present disclosure will be explained in more detail with reference to the accompanying drawings. The present disclosure may, however, be embodied in different forms than depicted below, and should not be construed as limited to any examples set forth herein. Rather, any examples are provided so that the disclosure will be thorough and complete, and will fully convey the scope of the invention to those skilled in the art. Like reference numerals refer to like elements throughout. Like elements will, thus, not be described in detail with respect to the description of each figure.

[0294] % Fig. 1 : display system with two observers

[0295] Fig. 1 shows a perspective view of an example configuration of the disclosed au- tostereoscopic or multi-view display.

[0296] A spatial light modulator (layer of liquid crystal cells) 1 is located in the optical axis between an LED array 2 (layer of light emitters, such as an OLED layer or inorganic LEDs) and a first observing eye 4. The distance between the LED layer and the layer of liquid crystal cells may be 40 mm.

[0297] A diffuser 3 may be comprised, located between the light modulator 1 and the LED array 2.

[0298] Further, a face tracking system 8 capable of tracking the position of the observing (eye) 4 and a controller 9 are comprised.

[0299] The controller may be connected to the face tracking system 8, to the LED array 2 and to the light modulator 1 and may be capable of receiving from the eye tracking system 8 a position of the first observing eye 4 and controlling the operation of the spatial light modulator 1 and the LED array 2 so a first image is visible in a first viewing zone comprising the first observing eye 4 and not visible in a second viewing zone comprising a second observing eye 5.

[0300] % Fig. 2: spatial light modulator with one light valve open

[0301] Fig. 2 shows a front view of an example configuration of the spatial light modulator 1.

[0302] The spatial light modulator 1 may comprise a plurality of vertically elongated light valve columns (liquid crystal cell, such as a ferro-electric liquid crystal cell) capable of binary operation with a fast response time, so the light valve columns can switch quickly between an open, essentially clear state having a high light transmission (light transmitting state) and a closed, essentially opaque state having a low light transmission (light shielding state). It may not necessarily be possible to achieve a light transmission of 0 % in the light shielding, e.g. for example LCD displays are known to have a small percentage of light transmission even when the liquid crystals are supposed to block light.

[0303] A number Nc of light valve columns (apertures / slits) may be comprised in the light modulator 1 , where Nc may be for example 32, such as more than 2, or more than 5 or 10 or 20 such as in the range 3 to 50 such as 10 to 40 such as 20 to 40.

[0304] The light valve columns may be arranged side by side as shown in fig. 2.

[0305] The dotted lines indicate outlines of the light valve columns. A light valve column may for example be one millimetre wide and 25 millimetre high and the gap between light valve columns may be minimized and may be for example 0.05 millimetre.

[0306] A light valve column may comprise a liquid crystal cell, such as a ferro-electric liquid crystal cell, and may have two polarisers configured according to WO2022057738A1 (Application PCT / CN2021 / 117681), which is hereby incorporated in the description by reference.

[0307] In one example, configuration light valve columns are polarity sensitive and the controller 9 is capable of directing a light valve column to open by applying a voltage of a first polarity over a liquid crystal cell comprised in the light valve column and of directing the light valve column to close by reversing the polarity.

[0308] In another example, configuration of the light valve columns are essentially polarity insensitive and the controller 9 is capable of setting a light valve column to either closed or open by applying a voltage of any polarity over the cell and of reversing the cells state by applying zero Volt or a low voltage.

[0309] In fig. 2, the light modulator 1 is shown with one light valve column open and the other light valve columns closed, hence the open light valve column will form an aperture capable of focusing in the horizontal direction a (vertical) light pattern generated by the LED array 2 towards the first observing eye 4.

[0310] % Fig. 3a: view of LED array

[0311] Fig. 3a shows a front view of an example configuration of the LED array 2. It may comprise for example a matrix of 210 x 90 LEDs with a horizontal and vertical pitch, e.g. centre to centre distances (LED pitch), of 0.5 millimetre.

[0312] With a LED pitch of 0.5 mm, an aperture width of 1 mm and a distance between the LED layer and LCD layer of 40 mm, the angular resolution of viewing zones is about 0.5 - 1 degrees, e.g. there may be one viewing zone per each 0.5 - 1 degrees.

[0313] LEDs may be white, or they may be RGB color LEDs each comprising three LEDs, a red, a green and a blue LED in one housing.

[0314] An RGB LED may be selected so the red, green and blue LEDs inside the common housing may be located essentially on a common vertical axis.

[0315] Alternatively separate red, green and blue LEDs may be used, which may likewise be located on an essentially common vertical axis.

[0316] LEDs can be SMD components, COB components or prefabricated arrays of LEDs which may be assembled together on a PCB, which can also hold the controller 9 or part of the controller 9.

[0317] Alternatively, LEDs may be organic LEDs, for example thin film OLED.

[0318] LEDs may be selected or configured so they have a high peak pulse brightness, for example so they can make a flash of high intensity with a duration of less than 0.7, such as 0.5 or 0.3 or 0.1 milliseconds.

[0319] For example, LEDs may be of the brand Everlight model CSP0603AN101- WP30300563001-3T.

[0320] LEDs may be selected for essentially similar characteristics including opto-electronic transfer function, centre wavelength and forward voltage drop. This may result in better uniformity of observed images on the disclosed display.

[0321] The LEDs may be controlled / scanned with a passive matrix addressing circuit with horizontal electrodes, e.g. data lines, connected to cathodes of LEDs in a row. Vertical electrodes, in this description also referred to as select lines, are connected to anodes of LEDs in a column.

[0322] Alternatively, data lines may be connected to anodes and select lines may be connected to cathodes.

[0323] The controller 9 may comprise current sources connected to data lines and switches connected at one end to corresponding select lines and at the other end to a common LED supply voltage. The current sources may be modulated by pulse amplitude modulation, e.g. the strength of a current may be controlled, or by pulse width modulation, e.g. a duration of a current may be controlled, or by combinations of pulse amplitude modulation and pulse width modulation.

[0324] Said in other words, the anode of all the LEDs in a column is connected to a switch, e.g. there is a switch for each LED column. Each switch is connected to a line called a “select line” - because a signal on that line switches on the switch and thereby “selects” a LED column.

[0325] Each LED has its cathode connected to a data line (row electrodes - extending horizontal).

[0326] A scan of the controller means that the controller sends a signal on the select line which switches on the switch so that the LEDs of a column emits light at a brightness corresponding (a function of) the data being provided to each LED by the data lines.

[0327] A scan of the display can also be said to constitute an update of the display (to a new set of images).

[0328] Not all LED columns are necessarily selected in an update of the display.

[0329] A current through an LED during a pulse may be for example 0-40 mA. Hence, a column of LEDs may be flashed with a desired set of perceived brightness values for LEDs in said column by controlling the constant current sources with a combination of modulation settings corresponding to the desired set of perceived brightness values and then for the duration no shorter than the flash activating a switch connected to a select line of said column of LEDs. Hence, the LED array 2 may be controlled to flash LEDs in a column with a desired perceived flash pattern of brightnesses and / or colours with high intensity.

[0330] The disclosed display may be operated at a so-called frame rate (fps) for example 60 “frames” per second. For the disclosed display this frame rate defines the number of multiplexing cycles per second. Where in each multiplexing cycle a set of images is presented to corresponding desired viewing zones, one image for each of the observing eyes, e.g. if there are two observers watching 3D content there is generated four images per multiplexing cycle, e.g. the display generates 240 images per second. The two observers may be presented with the same right eye images and the same left eye images, e.g. a 3D display without look around effect.

[0331] As mentioned, the multiplexing cycle may comprise a scanning phase where the controller 9 directs the light modulator 1 to open one light valve column at a time while keeping the other light valve columns closed. The scanning may be performed from left to right or in any other sequence for example in a non-consecutive sequence.

[0332] The controller 9 may receive eye position data from the face tracking system 8. For example, the controller 9 may receive eye position data periodically and store a copy of the last received eye position data in a memory. Additionally, the controller 9 may store or receive from an external source still images or moving images. It may store or receive a still or moving image for each eye in a set of observing eyes. For example, the controller 9 may store a first image intended for the first observing eye 4, a second image intended for the second observing eye 5, a third image intended for the third observing eye 6 and a fourth image intended for the fourth observing eye 7. Said first, second, third and fourth image may have a resolution of X pixel columns and Y pixel rows, where X may be equal to the number N of light valve columns and Y may be equal to a number of LEDs in a column in the LED array.

[0333] During each interval in which a light valve column is open, the controller 9 may flash a set of LED columns with flash patterns one set at a time.

[0334] The LED column positions and flash patterns are calculated using eye position data, as described in further details below, thereby providing a directional display having a horizontal angular resolution and a set of vertically elongated viewing zones where each may illuminate an observing eye.

[0335] % Fig. 3B

[0336] Fig. 3B illustrates a view of a LED array where at each node there is a collection of a red, green and blue LED for generating colours.

[0337] % Blanking interval / period

[0338] A multiplexing cycle may further comprise a blanking interval Tb (may also be referred to as blanking period), during which the controller 9 directs the light modulator 1 to open all light valve columns while directing the LED array 2 to switch off all LEDs. This may extend the lifetime of the light modulator 1 by eliminating or reducing a time integrated DC build up over the liquid crystal cells. Thus, there is a time window in which any DC offset may be compensated / brought towards 0.

[0339] The blanking interval Tb may be selected so the amount a liquid crystal cell is open during a duty cycle is essentially equal to the amount of time said liquid crystal cell is closed. For example Tb may be calculated as Tb = (1 / fps) x (Nc-2) I (2Nc-2) with for example fps = 60 and Nc = 32.

[0340] An interval during which a light valve column is open may then be calculated as ((1 / fps)- Tb) / Nc.

[0341] In a configuration the liquid crystal cells are essentially polarity insensitive the blanking interval may be omitted, e.g. Tb = 0.

[0342] % Superposition

[0343] Instead of having all light emitters turned off during the blanking period the blanking period may constitute what can be termed a “common superposition interval”. This is a time window in which an image may be generated for all observers (it is visible to all observers, because the light modulators are open during that time window / interval), e.g. all light modulators are open at the same time or have been open within the same time window. This time window being less than 50 % of the duration of the multiplexing cycle, e.g. at least 50 % less than the time it takes to generate the individual images for the active viewing zones. Thus, unless corrected during the rest of the multiplexing cycle, an observer observing only the image generated during the common superposition interval will have a 2D perception - and the image observed will be artificial in the sense that it is not forming part of the recorded contents / original movie.

[0344] The image generated during the common superposition interval is a function of the images for the active viewing zones. This image may be termed a common superposition image. The pixel values of the pixel at a first coordinate in the images for the active viewing zones are compared and the minimum value of the pixel values is determined.

[0345] A value being substantially equal (+ / - 25 %) to the minimum value of the pixel values at the same image coordinate of the images for the active viewing zones is determined. It does not have to be exactly the minimum value even though if it is not errors in the images will be introduced, but such errors might not be visible to the observer(s).

[0346] This is done for all image coordinates. Hereby is found the value at each coordinate / pixel of the common superposition image (CSI). It might not be pixels at exactly the same coordinates in each image that are compared. It could be the same coordinate within some radius, for example within 5 pixel pitches. This is because pixels within an area often have similar values, or values close to each other, unless it is the border between a star and a black space.

[0347] Mathematically for the pixel ij this may be written as:

[0348] CSIJj = min ( Im1_ij, Im2_ij ... lmN_ij ) where N is the number of active viewing zones, and ij is the coordinate pair / pixel address, and Im1 is a first image for a first active viewing zone, and I m2 is a second image for a second active viewing zone. The top left pixel in an image may have coordinate pair (1 ,1).

[0349] When the common superposition image has been determined, an individual superposition image (ISI) has to be determined for each active viewing zone. This image is a function of the common superposition image and the image for the active viewing zone (ImX). Specifically, it may be determined by subtracting the common superposition image from the image for the active viewing zone. Or performing an operation corresponding to a subtraction.

[0350] Mathematically this may be written as:

[0351] ISI = ImX - CSI

[0352] Hence, in an active viewing zone may be observed an image RSI which is a result of an optical superposition of the common superposition image CSI and an individual superposition image ISI, hence RSI = CSI + ISI. Since ISI = ImX - CSI it follows that RSI = CSI + (ImX - CSI) = ImX.

[0353] In other words, the observed image in said active viewing zone will be ImX, the image for said active viewing zone, as desired.

[0354] The observed image RSI is a result of an optical superposition of CSI and ISI. Therefore CSI and ISI should be calculated such that an optical superposition of CSI and ISI results in ImX. This may be done by using the above calculations on pixel values in a linear color space, i.e. a color space, where pixel values are linear function of optical power of pixels.

[0355] In existing image storage and transmission systems, pixel values are often represented as non-linear function of optical power of pixels. Examples of such non-linear functions are gamma encoding and perceptual encoding. When pixel values are represented by non-linear functions of optical power, they may me be converted to linear functions before the above image calculations. An LED matrix may be designed to input pixel values represented as non-linear functions of optical power. In this case the resulting images CSI and ISI may be converted using non-linear functions before being input to the LED matrix.

[0356] For example: an image generator outputs Im1-N encoded with a gamma of 2.2 and the LED matrix is designed to receive image inputs with a gamma 2.2 encoding. In this case, a controller of the Hybrid Scan Display may perform a reverse gamma 2.2 encoding of the input from the image generator, calculate CSI and ISI, and then re-apply the gamma 2.2 encoding to CSI and ISI. As an example, the display is to generate two images, because there are at least two active viewing zones.

[0357] Then the pixel value of a first pixel in the first image is compared to the pixel value of a first pixel in the second image (the two pixels having the same coordinates in the two images or substantially within the same position in the two images - within 5 pixel pitches for example). The lowest of these two pixel values then constitutes the pixel value of a first pixel in the common superposition image.

[0358] Then the pixel value of a second pixel in the first image is compared to the pixel value of a second pixel in the second image (the two pixels having substantially the same coordinates in the two images). The lowest of these two pixel values then constitutes the pixel value of a second pixel in the common superposition image, and so forth until all pixel elements of the common superposition image has been determined.

[0359] Then the two individual superposition images are to be determined. For the first individual superposition image the common superposition image is subtracted from the first image, and for the second individual superposition image the common superposition image is subtracted from the second image.

[0360] The determination of the minimum pixel values and the linear operation (subtraction) may be performed in Gamma space, e.g. applying a gamma correction before the two mentioned operations.

[0361] As a specific example, the display may have a resolution of 2 by 2 pixels in greyscale. A single observer is observing the display. The right eye image and the left eye image has the following pixel values in an 8 bit space, e.g. each pixel may have a value between 0 and 2A8.

[0362] Right eye image pixel values:

[0363] Left eye image pixel values:

[0364] First the values are normalized by dividing with 2A8:

[0365] Right eye normalized image pixel values:

[0366] Left eye normalized image pixel values:

[0367] This is now to be gamma corrected, e.g. transferred to a logarithmic space (gamma space) where the values of images may be operated on linearly (added or subtracted), because the human eye sensitivity is logarithmic.

[0368] The transfer function may be a power of 1 / 2.2, e.g. xA(1 / 2.2). Other gamma correction values than 2.2 may be used. This results in the values:

[0369] Right eye gamma corrected image:

[0370] Left eye gamma corrected image:

[0371] The common superposition image is determined by comparing each image pixel by pixel, for example starting with the first pixel in the top row and determining which pixel value is the lowest. In the specific example the common superposition image is then:

[0372] Then each individual superposition image has to be determined. For each individual superposition image this may be done by subtracting the common superposition image from the gamma corrected image:

[0373] Right eye individual superposition image:

[0374] Left eye individual superposition image:

[0375] When generating these three images (the common superposition image, the right eye individual superposition image, and the left eye individual superposition image) the four pixel values of each image are provided to the display. The values may be provided to the display either as gamma corrected values or they may be transferred to linear space, e.g. by a logarithmic function xA2.2. This depends on what the display is set up to receive.

[0376] In the above the pixel values have been gamma corrected, and the common superposition image has been found in gamma space. However, there are other specific ways than gamma correction to adjust for the human eye sensitivity. The specific power of 2.2. used in this example may also be another number.

[0377] For a color image this would have to be done for all colors, e.g. color by color so that a red common superposition image is determined, a green one and a blue one and then the individual superposition image for each color.

[0378] As mentioned, an observer observing only the image generated during the common superposition interval will have a 2D perception - and the image observed will be artificial. In order for that observer to observe a non-artificial image but rather an image that was recorded it is contemplated that for example when the right eye individual superposition image is generated, the light modulators are controlled so that all observers observing 2D content will receive the right eye individual superposition image in addition to the common superposition image. It could also be that all observers observing 2D content will receive the left eye individual superposition image in addition to the common superposition image or an image that is an average or a function of the right eye individual superposition image and the left eye individual superposition image. This could be termed a “2D superposition image (2DSI)”. Thus, in such a case the display is controlled to generate at least a common superposition image, a right eye individual superposition image, a left eye individual superposition image, and a 2D superposition image during a multiplexing cycle. As an example with one observer observing 3D and one observer observing 2D the following images are generated during a multiplexing cycle:

[0379] CSI + ISI_1 + ISI_2 + 2DSI

[0380] It could also be that as mentioned in connection with fig. 4E to 4F the right eye image is visible everywhere else except all left eyes for observers observing 3D. In this case the following images are generated during the multiplexing cycle:

[0381] CSI + ISI_1 + ISI_2

[0382] This will actually be the same as for the case where the left eye image is visible everywhere else except all right eyes for observers observing 3D.

[0383] It will also be the case when all observers observing 3D are to observe the same 3D images, e.g. all right eyes receive the same right eye image and all left eyes receive the same left eye image.

[0384] As an alternative to the above scheme the display may comprise a fan for generating a flow of a cooling fluid such as air across a surface in thermal connection with the light emitters for cooling the light emitters.

[0385] % figs. 3C and 3D

[0386] In fig. 3C are illustrated three images. A common superposition image, a first individual superposition image, and their sum, which is a first image. In fig. 3D are illustrated three images. A common superposition image, a second individual superposition image, and their sum, which is a second image. The common superposition image is the same in both fig. 3C and fig. 3D.

[0387] % Fig. 4A: a first step in the multiplexing cycle

[0388] Fig. 4A is a top view of an example configuration of the disclosed display shown at a point in time of a multiplexing cycle where light valve column M is open, M being the column position counted from the left, and the other light valve columns in the spatial light modulator 1 are closed.

[0389] Light valve column M is open for a time interval T as mentioned above.

[0390] During the time interval a set of LED columns (light spreader) 10 may be flashed with patterns essentially equal to a first LED column pattern (a column of the image to be displayed). In the present example three LED columns are illustrated as being flashed at the same time (in order to illuminate the whole aperture).

[0391] It is contemplated that an aperture is to be so narrow compared to the set of LED columns (light spreader) that light emitted from an edge of the light spreader is blocked while light emitted closer to the center of the light spreader is transmitted through the aperture (when the aperture is open).

[0392] Ray tracing may be used to determine how narrow an aperture is to be compared the set of LED columns, e.g. enough LED columns has to flash light so that light from the edge will be blocked. This will ensure that the whole width of the aperture is illuminated.

[0393] Thus, the controller 9 may calculate the set of LED columns 10 using the received eye position data so the set of LED columns 10 illuminate a pattern which fills out horizontally the light valve column M as observed by the first eye.

[0394] For example, the controller 9 may calculate a centre and a width of an area on the LED array 2 corresponding to an area on the diffuser 3 which is observed by the first eye through light valve column M and then selecting the set of LED columns 10 to include LED columns which are fully or partially covered by said area. In the example three LED columns flashes light. The controller 9 may further calculate said first LED column pattern so it corresponds to pixel values in pixel column M in the first image. Hence, the first eye sees light valve column M filled out horizontally with a vertical pattern corresponding to pixel values in pixel column M of the first image.

[0395] Hence when a full duty cycle / multiplexing cycle is completed in a similar way in for example 1 / 60thof a second (when all apertures has been scanned - and the LED columns has been scanned as many times as there are eyes watching the display), the temporal integration of light in a human visual system will cause the first eye to see the first image displayed in full on the spatial light modulator 1 , where the width of pixels is defined by the width of light valve columns and the height of pixels are defined by the height of LEDs plus any vertical smearing by the diffuser 3. The same will be the case for the second eye.

[0396] The display does not generate the images sequentially, e.g. one image after the other, instead part of each image to be displayed to the different eyes is generated when one aperture is open and so forth for each aperture. It could be said that when only considering one eye there is a pause between the generation of each column of the image - but the eye is not fast enough to see that. And in that pause a part of each of the other images is generated. When the scan of the apertures is complete an image has been generated to all eyes.

[0397] % Fig. 4B: a second step in a multiplexing cycle

[0398] Fig. 4B shows the configuration in fig. 4A during the same interval as in fig. 4A, where a second set of LED columns 11 may be flashed in a similar way to the above description, hence creating a vertical pattern in light valve column M as perceived by the second eye 5 corresponding to pixel column M of the second image.

[0399] Thus, so far an image column has been generated to the first eye and the second eye.

[0400] % Fig. 4C: a third step in a multiplexing cycle

[0401] Fig. 4C shows the configuration in fig. 4A during the same interval as figs. 4A and 4B where a third set of LED columns 12 may be flashed in a similar way to the above description, hence creating a vertical pattern in light valve column M as perceived by the third eye 6 corresponding to pixel column M of the third image. Thus, so far an image column has been generated to the first eye, the second eye, and the third eye.

[0402] % Fig. 4D: a fourth step in a multiplexing cycle

[0403] Fig. 4D shows the configuration in fig. 4A during the same interval where a fourth set of LED columns 13 may be flashed in a similar way to the above description, hence creating a vertical pattern in light valve column M as perceived by the fourth eye 7 corresponding to pixel column M of the fourth image.

[0404] Now an image column has been generated to all of the eyes and the next aperture may be scanned / opened.

[0405] When a specific aperture is selected / scanned such that it opens for light transmission, the controller then determines which LED columns are to be scanned such that it emits light - the specific LED column depends on the viewing zone once the aperture has been selected.

[0406] This happens one aperture at a time until the scan sequence has cycled through all of the apertures - completing the multiplexing cycle.

[0407] Thus, the liquid crystal cells are scanned with a frequency (number of occurrences of a repeating event per unit of time) of (Fc) = (Nc) / Tm (outside a blanking interval) while the LED columns are scanned at a higher frequency (Fc) x (Nz) - in the example four times higher.

[0408] % Only selected LED columns flash light

[0409] Note that the sequence in which LED columns are flashed during the time interval T may not necessarily be in the order described above, e.g. fig. 4 is an example.

[0410] The LED columns may be flashed in any order as long as they are flashed during the time interval T, e.g. the controller “jumps” between the LED columns - it is a non-con- secutive sequence where a first LED column and a second LED column that is scanned during an open liquid crystal cell may be separated by a number of LED columns, e.g. there is a distance between the two - they are not neighbours.

[0411] % set of LED columns A number of neighboring columns may emit light at each step in the multiplexing cycle, e.g. a number of neighboring columns may be scanned for emitting light. In such a case each neighboring column emits the same light pattern - it is to ensure that the aperture is filled out.

[0412] For example, LED columns in a set of LED columns may be flashed with essentially the same light patterns, such as for example the set of LED column patterns 10 could be flashed simultaneously by activating the corresponding three switches in the passive matrix addressing circuit simultaneously, and setting the constant current drivers to three times the current. Another number than three columns may be contemplated, such 2 or 4 or 5 or 6 or 7 or 8 or 9 or 10.

[0413] In this configuration, LEDs may be selected for essentially similar values of forward voltage drop to ensure better uniformity of brightness patterns of LED columns in the first set of LED columns 10, since in this configuration with all three switches anodes will be connected to the common LED voltage supply while cathodes are connected to a common data line, hence LEDs in the set of LED columns 10 will be essentially coupled in parallel.

[0414] % Fig. 4E: No diffuser

[0415] A diffuser may be used to improve the image quality for the solution disclosed in connection with figs. 4A to 4D.

[0416] As may be recalled, the diffuser may be configured so horizontal edges of an observed illuminated area in an aperture are delimited by the edges of the aperture. In other words, a substantially horizontally evenly illuminated part of the diffuser 3 fills out an aperture as viewed from the viewing zone. Hence the wider a horizontally evenly illuminated part of the diffuser 3 and the narrower an aperture is, the greater will be the angular extent of the viewing zone wherein the aperture will be filled out with light and hence pixels appear with consistent brightness and colour, which is important for a good image quality.

[0417] As may be recalled, for figs. 4A to 4D an aperture (light modulator scanned to be in a light transmitting state) is to be fully illuminated, and it is illuminated with a light pattern of a pixel column in an image defined by (is a function of) the position of the aperture, e.g. as mentioned if column / light modulator / aperture M of the light modulators is scanned then the light emitter column emits a light pattern defined by column M in the image to be displayed in the respective viewing zone (the light emitter column that is scanned to emit the light pattern is the one that directs light to the respective viewing zone, and that light emitter may have another column number than M). With position is meant column position / number. Thus, for figs. 4A to 4D the horizontal resolution of the display is determined by the number of light modulators on a row / number of light modulators arranged horizontally.

[0418] However, the diffuser may be omitted while the image quality maintained. For achieving this a different scanning than in figs. 4A to 4D may be used. This is disclosed below.

[0419] % resolution = number of light emitters arranged horizontally

[0420] For the scanning for a solution without diffuser it is contemplated that all light emitter columns are to be scanned for emitting light, e.g. in order to display a full image essentially (>95 %) all light emitter columns are to be scanned for illuminating light during a multiplexing cycle.

[0421] A light emitter column is scanned for illuminating light with a light pattern defined by a column in the image to be displayed in the respective / active viewing zone having a horizontal position corresponding / equal to the horizontal position of the light emitter (column).

[0422] This also means that the image pattern that a light emitter column is to emit is independent of which light modulator that is open, e.g. for figs. 4A to 4D if light modulator M was scanned the light emitter column was to be scanned with values for emitting a light pattern defined by column M in the image to be displayed in the respective viewing zone as mentioned.

[0423] For the scanning for a solution without diffuser it is contemplated that if light emitter column N is to emit light it may be scanned with values for emitting a light pattern defined by column N in the image to be displayed in the respective viewing zone (a light emitter column N may be scanned for illuminating / emitting a light pattern corresponding to pixel column N in the image). N and M being different columns.

[0424] Said in other words, at a step in a multiplexing cycle the controller controls the light modulators such that a number of neighboring light modulators are in a light transmitting state for defining an aperture at a first position, and the controller controls the light emitters such that a first light emitter at a second position emits a light pattern of a pixel column in an image defined by the position of the first light emitter. The first light emitter may have a position different from the first position.

[0425] % Wide aperture

[0426] Fig. 4E shows a top view of the light modulator 2 at three different times during a multiplexing cycle (T1 , T2 and T3).

[0427] White colour means that a light modulator is open and black colour means that a light modulator is closed.

[0428] It is illustrated that the light modulators alternate between a wide light modulator and a more narrow light modulator, e.g. at each side of a wide light modulator there is a light modulator that is more narrow. Thus, the plurality of light modulators include at least a first light modulator and a second light modulator that has a width smaller than the width of the first light modulator. Three neighbouring light modulators are open at the same time, e.g. one wide and two narrow.

[0429] It is contemplated that the aperture is made wider than for figs. 4A to 4D. Specifically wider than a pitch (center-to-center distance) of the apertures, e.g. a width of an aperture should not be smaller than a pitch (center-to-center distance) of apertures, in order not to block visibility of any light emitters.

[0430] This may eliminate horizontal boundaries between apertures,

[0431] The aperture may be made wider by scanning the light modulators such that a set / num- ber of neighbouring light modulators are in a light transmitting state (at the same time).

[0432] As may be recalled for the solution described in connection with figs. 4A to 4D it could be that a number (greater than one) of neighbouring light emitters were scanned to emit light at the same time to ensure a fully illuminated aperture. Now it is the opposite: the aperture is to be wider than the light emitter, e.g. the distance between the right edge and the left edge of the aperture is to be greater than the distance between the right edge of a light emitter and the left edge of the light emitter. The distance illustrated with W is to illustrate the physical / total width of a number of neighbouring light modulators that are in a transmitting state and define the aperture.

[0433] This is also different from figs. 4A to 4D, where an aperture is defined by a single light modulator.

[0434] % Neighbouring LED columns flashing different light patterns

[0435] During the time period when a specific aperture / neighbouring light modulators are open, for each active viewing zone / eye the light emitters in the columns that are visible from that respective active viewing zone through the aperture are to be scanned in order to emit light.

[0436] Thus, if light emitter columns L and N are visible (through aperture M) from a respective viewing zone columns L and N are to be scanned with pixels values from columns L and N from the image to be displayed

[0437] The interleaved sequence is then different from figs. 4A to 4D where a single image part / column is generated and then a single image part of another image is generated after that. Now, two image parts / columns may be generated before two image parts of another image part is generated.

[0438] For example, with two active viewing zones, such as a right eye zone and a left eye zone, two images are to be displayed, a right eye image R and a left eye image L. With six liquid crystals each image is divided into six parts: R1 , R2, R3, R4, R5, R6, L1 , L2, L3 L4, L5 and L6. The interleaved sequence IS will then be:

[0439] IS: R1 , R2 L1 , L2, R3, R4, L3, L4, R5, R6, L6.

[0440] Thus, the display controller is arranged for scanning the plurality of light emitters such that when a number of neighbouring light modulators (of a module) are in a light transmitting state a first light emitter at a first position emits a light pattern of a pixel column in a first image defined by said first position, and a second light emitter at a second position being neighbour to said first light emitter emits a light pattern of a pixel column in the first image defined by said second position when there is a line of sight between said first position and a center of an active viewing region (eye pupil) through said number of neighbouring light modulators, and there is a line of sight between said second position and the center of an active viewing region (eye pupil) through said number of neighbouring light modulators.

[0441] Said in other words, a line of sight between the center of an active viewing zone and the right edge of an aperture has a first intersection with the backplane, e.g. layer of light emitters. And a line of sight between the center of an active viewing zone and the left edge of the aperture has a second intersection with the backplane, e.g. layer of light emitters. Only light emitter columns that are between the two intersections are to be scanned for emitting light.

[0442] If there is such a line of sight or not may be determined by means of the tracking system and the controller.

[0443] % Pitch of aperture

[0444] The distance illustrated with P is to illustrate the aperture pitch (center to center distance between two neighbouring apertures - when a first set of neighbouring light modulators define a first aperture at a first step in a multiplexing cycle and a second set of neighbouring light modulators define a second aperture at a second step in the multiplexing cycle and these two apertures being next to each other albeit not at the same time).

[0445] The pitch is independent of the scanning sequence, e.g. it will be the same whether the light modulators are scanned sequentially or non-sequentially.

[0446] When an aperture is defined by a wide light modulator and a narrow light modulator the pitch is the center-to-center distance between two wide light modulators closets to each other. When an aperture is defined by a number of equally wide light modulators the pitch corresponds to the combined width of the number of light modulators.

[0447] For the solution described in connection with figs. 4A to 4D the pitch is the same as the aperture width (P = W). However, for the solution described in connection with fig. 4E the pitch is smaller than the aperture width (P < W).

[0448] Thus, in general it is so that during a multiplexing cycle the light modulators are scanned (by a controller) such that at a first step in the multiplexing cycle a first set of neighbouring light modulators are in a light transmitting state thereby defining an aperture at a first position. At a second step in the same multiplexing cycle a second set of neighbouring light modulators are in a light transmitting state thereby defining the aperture at a different position than where it was when the first set of light modulators were open.

[0449] The two steps does not have to be subsequent / next to each other in time.

[0450] However, the two sets have an intersection of at least one light modulator, e.g. at the first position of the aperture a first light modulator is scanned / controlled to be in a light transmitting state thereby defining a part of the aperture at the first step. And at the second step where the aperture is at the second position, the first light modulator is also scanned to be in a light transmitting state thereby defining a part of the aperture at the second step. Thus, the same light modulator is shared between two apertures (although not at the same point in time). Said in other words a light modulator is shared between the aperture when it is at the first position and when the aperture is at the second position, e.g. there is a light modulator in common although at different times. This means that there is an overlap between at least two of the positions that the aperture has occupied during a multiplexing cycle

[0451] The number of neighbouring light modulators in a set may be in the range 1 to 15, or 1 to 12, or 1 to 10, or 1 to 8, or 1 to 6, or 1 to 4, or 1 to 3, or 2 to 15, or 2 to 12, or 2 to 10, or 2 to 8, or 2 to 6, or 2 to 4, or 2 to 3.

[0452] At each position of the aperture, it is wider than the width of a single light modulator.

[0453] % Safe opening

[0454] Light emitters having a small horizontal extent and / or are pulsed / flashes or changing their value during a multiplexing cycle may cause a moving observer to miss a part or parts of the image where a light emitter column appear close to an edge of an aperture (as observed by an observer), e.g. if a line of sight from the center of an active viewing zone (center of an eye pupil) to the center of a light emitter is close to an edge of an aperture.

[0455] This may be the case for active areas of light emitters having a very small horizontal extent. For example the light emitters may be microLEDs with active areas having a horizontal width smaller than 100 urn. LEDs may be inorganic microLEDs capable of pulsing (flashing) with high peak pulse brightnesses. Combined with pulsed (flashed) light emitters, or light emitters changing between pixel values for different images during a multiplexing cycle.

[0456] The discrete nature of both the light emitter columns and apertures may cause such missing parts of the image result in distracting interference patterns unless the observer is absolutely still and tolerances are very low. In other words, the angular extent of a viewing zone having good image quality may be too small to accommodate for mechanical tolerances, precision and latency of an eye tracking system etc.

[0457] The distance illustrated with S is to illustrate the width of a safe-opening, and is a logical width, e.g. defined logically, and not by a physical object(s). It may have a value between P and W, for example it may be equal to P. Said in other words, the width W may be selected to be larger than the safe-opening S, for example 5%, 10%, 25% or 50% larger.

[0458] For reducing distracting interference patterns the light emitters that are se- lected / scanned for emitting light when a specific aperture / neighbouring light modulators are open may be reduced compared to as mentioned above, e.g. only light emitter (columns) visible through the safe-opening should be scanned for emitting light.

[0459] Said in other words, a line of sight between the center of an active viewing zone and the right edge of the safe-opening has a first intersection with the backplane, e.g. layer of light emitters. And a line of sight between the center of an active viewing zone and the left edge of the safe-opening has a second intersection with the backplane, e.g. layer of light emitters. Only light emitter columns that are between the two intersections are to be scanned for emitting light.

[0460] Hence, the position of the center of an active viewing zone may be moved during a multiplexing cycle. Thus, the observer may be able to move some distance away from the center position and still see all illuminated columns.

[0461] The safe-opening may be selected or adjusted so no missing parts of the image appear at any time, for example such that no disturbing visible line flicker is observed, for an observer who is being tracked by an eye tracking system having a precision and a latency, and where the active viewing zone is determined by (i.e. is a function of) eye position data from the eye tracking system. % Flag

[0462] The controller may be arranged for keeping track of which light emitters has emitted light such that for an active viewing zone / eye a light emitter has not emitted light more than once during a multiplexing cycle, e.g. a light emitter that has emitted light for an active viewing zone may be flagged by the controller so that it should not emit light for that viewing zone again during the multiplexing cycle.

[0463] Thus, for an active viewing zone such as an eye of an observer the controller may be arranged for controlling the plurality of light emitters such that a respective light emitter not emits light to an active viewing zone more than once during a multiplexing cycle, e.g. emits light a single time to that active viewing zone during the multiplexing cycle.

[0464] % Fig. 4F

[0465] As mentioned, the wide light modulator may be substituted by a plurality of light modulators such that all light modulators have the same width. This is illustrated in fig. 4F.

[0466] W, P and S are the same as in the previous figure, but the number of light modulators in the set is 6 instead of 3.

[0467] % fig. 4G

[0468] Fig. 4G shows a flow chart for operating a display according to the solution described in connection with figs. 4E to 4F.

[0469] During a multiplexing cycle a set of images are displayed, one to each active viewing zone.

[0470] The first box from the top shows that a first operation in a duty cycle may comprise the controller inputting a set of images to show during the multiplexing cycle comprising an image for each active viewing zone. Such input may for example include receiving a frame of a video signal comprising the set of images arranged together in one picture and cropping out images from the set. Alternatively, it may comprise receiving a high speed video signal with images in the set arriving sequentially. The video signal may be received over for example one or more HDMI or DP video interfaces. The controller may comprise an FPGA (field programmable gate array) or an ASIC (application specific integrated circuit) for fast video processing. The second box from the top shows that a second operation in a multiplexing cycle may comprise inputting eye- or head-tracking data from an eye- or head tracking system and calculating active viewing zones from those input data. Said calculation may comprise calculating an eye box and setting a viewing zone substantially equal to an eye box. A center of an eye box may be calculated to be substantially equal to an eye pupil. A width of an eye box may be calculated to be substantially equal to an eye pupil distance (interocular distance) of an observer minus a tolerance margin. The tolerance margin may be calculated as a fraction of an eye pupil distance, for example 25% or 50%.

[0471] The third box from the top indicates that a third operation in a multiplexing cycle may be to open the first slit, a slit meaning here an aperture, which may comprise a set of light modulators as described above, and which may have an overlap with neighboring apertures.

[0472] The fourth box from the top indicates that a fourth operation in a multiplexing cycle may be to illuminate one or more column(s) of light emitters for a first viewing zone which may comprise a first eye, as further described in detail for fig. E.

[0473] The fifth box from the top indicates that a fifth operation in a multiplexing cycle may be to determine if there are more active viewing zones to illuminate for the current open slit, where an active viewing zone may comprise an eye.

[0474] The sixth box from the top indicates that a sixth operation in a multiplexing cycle may be to scan one or more column(s) of light emitters for a next viewing zone which may comprise a next eye, as further described in detail in fig. E.

[0475] The seventh box from the top indicates that a seventh operation in a multiplexing cycle may be to determine if there are more active viewing zones to illuminate for the current open slit, where an active viewing zone may comprise an eye.

[0476] The eighth box from the top indicates that an eight operation in a multiplexing cycle may be to determine if there are more slits to be opened in the light modulator in order to achieve that substantially all slits have been opened. The box to the right of the eight box from the top indicates that a ninth operation in a multiplexing cycle may be to close a currently open slit and open another slit, which has not yet been open during the duty cycle. It is noted, that some of the above-described operations, such as the fourth and the sixth operation, may take varying time to perform for different slits, hence the open time of slits may vary from one slit to another slit and hence light modulators may have been open for different durations during the above described operations. The controller may keep track of how long time each light modulator has been open during the above operations.

[0477] The ninth box from the top indicates that a tenth operation in a multiplexing cycle may be to perform a DC balance / maintenance operation. The DC balance maintenance operation may be divided into two intervals, a Clear Window Interval, during which substantially all light modulators may be open and a DC Balance Interval, during which light modulators may be individually open and / or closed for some or all of the time, so that all light modulators have been open or closed the same amount of time during a full multiplexing cycle (a multiplexing cycle including a DC balance / maintenance operation).

[0478] A duration of the Clear Window Interval may be calculated to be substantially equal to the accumulated closed time for the light modulator which had the shortest accumulated closed time during the above-described operations.

[0479] A duration of the DC Balance Interval may be calculated to be substantially equal to the accumulated closed time for the light modulator which had the longest accumulated closed time during the above-described operations minus said duration of the Clear Window Interval.

[0480] During the DC Balance Interval the controller may open a light modulator in an interval substantially equal to a closed time during above described above operation minus the Clear Window Interval.

[0481] During the remainder of the DC Balance Interval, the controller may open said light modulator during half of the remainder of the DC Balance Interval and close said light modulator during the other half.

[0482] As may be recalled, a higher voltage Von may be used for opening light modulators than a voltage used for closing light modulators Voff. In such a configuration intervals in the above description of the DC balance maintenance operation may be shortened, for example by a ratio Rdc = Voff / Von.

[0483] During the Clear Window Interval interval, the Common Superposition Image described above (CSI) may be displayed.

[0484] % Fig. 4H

[0485] Fig. H shows a flow chart of an example of the sub-operation of illuminating columns for an active viewing zone, which may comprise an eye, when a slit (an aperture) is open.

[0486] The first box from the top indicates a first operation of this sub-operation, in which operation which a set of light emitter columns to be illuminated are determined. This operation may comprise calculating: a) a set of lines passing through a horizontal center of said active viewing zone, for example through a horizontal center of an eye, and also passing through a horizontal center of light emitter columns, and b) calculating a subset of the set of lines, which pass through a safe opening S of said slit / aperture, and c) calculating a set of light emitter column(s) through which lines in said subset of lines pass through a horizontal center.

[0487] These calculations may be performed by means of the controller using geometric calcu- lations / equations.

[0488] The second box from the top indicates a second operation of this sub-operation, in which the calculated set of light emitter column(s) are scanned for emitting light. This operation may comprise scanning light emitter column(s) in the set of light emitter column(s) with light patterns corresponding to pixel patterns in pixel columns in an inputted image for the active viewing zone, where the horizontal position(s) of pixel column(s) in the image is / are corresponding to the horizontal position(s) of light emitter columns as mentioned.

[0489] %Figs. 41 to K Figs. I, J and K show a top view of the solution described in connection with figs. 4E and 4F during operation / displaying images at three different time intervals. Four active viewing zones are illustrated.

[0490] For each time interval the aperture is at a position, and a number of light emitters emit light through the aperture to each active viewing zone.

[0491] Lines of sight between the center of an active viewing zone and a light emitter through the aperture are indicated with lines.

[0492] It can be seen on fig. 4I that two light emitter columns are visible to eye 6 and emit light to that active viewing zone.

[0493] In figure 4J no light emitter columns emit light for eye 6, because there are no light emitters with a line of sight to eye 6 that has not already emitted light for eye 6. Thus, the light emitters where there is a line of sight to eye 6 in fig. 4J has been flagged already.

[0494] As mentioned, a width of the safe-opening S may be equal to a pitch of the apertures + / - 25 %, or + / - 10 %. When having a safe-opening and flagging light emitters active viewing zones may be determined before a multiplexing cycle and not changed during the multiplexing cycle.

[0495] Hence each column of light emitters may be illuminated once and only once for each image during a duty cycle, because a calculation of visible column of light emitters for each safe-opening may comprise exactly all visible columns.

[0496] In an alternative configuration the safe-opening S is larger than the pitch P and the active viewing zones may be determined or changed during a duty cycle. This configuration has the advantage of lower delay from the tracking eyes to the emission of light to eyes, hence allows greater precision and less flicker at fast movements and / or greater viewing distances.

[0497] In the latter configuration (S > P), the controller has to keep track of which light emitters has emitted light such that for a viewing zone a light emitter has not emitted light more than once during a multiplexing cycle. Thus, during a multiplexing cycle each light emitter (in a logical module) emitting light equal to the number of active viewing zones

[0498] - not withstanding light emission to don’t care viewing zones. This may for example be implemented by setting a flag for a pixel column in an image, when said pixel column has been shown, and showing pixel columns, which do not have their flag set.

[0499] % Double FLCD

[0500] In connection with fig. 9 it is described that a second plurality of light modulators may be used, e.g. a display with a double light modulator layer. The layer that may be added in is for increasing the black level. It may be controlled as described in connection with fig. 4E in that a set of light modulators are open and define an aperture that is wider than a single light modulator. There is also two positions of the aperture where a light modulator is shared as also described in connection with fig. 4E.

[0501] When a display has two light modulator layers one of the layers will be controlled such that the aperture in that layer is more narrow than the aperture in the other layer. This is independent from how the light emitters and light modulators otherwise are scanned, e.g. if it is as described in connection with figs. 4A to 4D or as in fig. 4E.

[0502] When a display has two light modulator layers and the light emitters and light modulators are scanned as described in connection with fig. 4E both layers have an aperture that is wider than a single light modulator.

[0503] % Summary

[0504] The following can be summarized for the solution described in connection with figs. 4A to 4D:

[0505] - there is an interleaved scanning sequence of the light emitters,

[0506] - an aperture is fully illuminated, and

[0507] - at a step in multiplexing cycle an aperture is illuminated with a light pattern of a pixel column in an image defined by the position of the aperture.

[0508] While for figs. 4E to 4F:

[0509] - there is an interleaved scanning sequence of the light emitters, - an aperture is wider than a light modulator,

[0510] - there is an overlap between at least two of the positions that the aperture has occupied during a multiplexing cycle, and

[0511] - at a step in multiplexing cycle an aperture has a first position, and a light emitter at a second position emits a light pattern of a pixel column in an image defined by the position of the light emitter.

[0512] % Fig. 4L to 4N: sliding window

[0513] Figs. 4L to 4N illustrate an example where the display is controlled such that the liquid crystal cells do jump, e.g. in figs. 4A to 4D each liquid crystal cell in a module is open one time during a multiplexing cycle, and when it is open a number of LED columns flash light (to the active viewing zones through the crystal cell that is open).

[0514] In the following example, the situation is “opposite” sort of say, e.g. now it is the liquid crystals that “jumps” - or are selected as a function of the observer positions. In the example of figs. 4a to 4d it was the LED columns that were selected as a function of observer position.

[0515] The drawback of the example of figs. 4L to 4N is that the display is only able to generate the same right eye image to all right eyes and the same left eye image to all left eyes. Thus, the observers cannot observer different contents or have a look-around effect for example.

[0516] However, in the example of figs. 4L to 4N the LED columns may be scanned one after the other in a sequence, e.g. the display comprises light emitters arranged in columns, and at each step in the multiplexing cycle the light emitters in a column emit light - one column at a time.

[0517] This is as such not different from what has been disclosed so far in the present disclosure. The difference is that the sequence is independent from observer positions, e.g. the controller does not require an input from any observer tracking system in order to scan the columns in the correct order. The sequence is not necessarily sequential, e.g. from left to right or from right to left. Other scan sequences than from left to right may be contemplated as long as all LED columns per module are scanned. However, in the case that the sequence does go from left to right or vice versa the scheme may be called a “sliding window”.

[0518] The sequence defining the order in which the columns emit light may be referred to as the scan sequence. The term “scanned” is used to refer to the addressing of a column by the controller such that a current will pass through each light emitter in the column such that each light emitter emits light - the current through each light emitter being a function of the value of the pixel that the respective light emitter is to generate. Typically, there is a driver for each light emitter in the column that is scanned, and upon the scanning a pixel value is read into each driver in the column.

[0519] At the beginning of a multiplexing cycle a first LED column emits light such that a first image part of a first image is generated.

[0520] The first image part may be a (single) column of pixels - this is the same as for figs. 4a to 4d, e.g. one (single) image part is generated one after the other in both variants of the 3D display.

[0521] The first LED column may be the LED column to the far left of the display.

[0522] In a subsequent step a second LED column emits light such that a second image part of the first image is generated. This may be the one next to the first.

[0523] Fig. 4L illustrates a step close to halfway into the scan of the LED columns for generating the first image.

[0524] The liquid crystal cells are controlled such that the light from the first LED column is visible for all right eyes, e.g. the liquid crystal cells that are to be open for light transmission are the ones that are in the paths between the first LED column and all the right eyes.

[0525] In fig. 4L there are two right eyes so two liquid crystal cells are open, e.g. there is one open liquid crystal cell per right eye. The liquid crystal cells that are selected to be open by the display control circuit when the first LED column emits light depend on the positions of the right eyes in front of the display, e.g. it is a function of the observer positions.

[0526] Observer tracking such as eye tracking or head tracking may be used to determine the position of the eyes.

[0527] When all image parts for the first image have been generated the procedure is repeated for the left eyes, e.g. during a multiplexing cycle the light emitter columns are scanned twice. Thus, each light emitter column emits light twice. A first time for all right eyes and a second time for all left eyes. It can be said that there are two picture frames per multiplexing cycle.

[0528] Thus, for the second image the first LED column emits light such that a first image part of a second image is generated.

[0529] Fig. 4N illustrates a step about 1 / 3 into the scan of the LED columns for generating the second image, e.g. about 1 / 6 + 1 / 2 = 4 / 6 into the multiplexing cycle.

[0530] During the generation of the second image, the liquid crystal cells are controlled such that each time a light emitter columns flashes light it is visible for all left eyes.

[0531] In a subsequent step the second LED column emits light such that a second image part of the second image is generated, and so forth until all image parts for the second image has been generated.

[0532] The scan sequence of the light emitter columns does not have to be the same when generating the first image and the second image.

[0533] As an alternative to the above, the generation of the two images could be interleaved, e.g. in a first step in the multiplexing cycle a first image part of the first image is generated by a first LED column and in a subsequent step (the next step) a first image part of a second image is generated by a second LED column (which may be the same as the first LED column.

[0534] % Inactive viewing zone DC balance for sliding window In the following is described how DC balance of the light modulators may be achieved in yet an alternative implementation.

[0535] Specifically, it is directed to the example above of the display described in connection with figures 4L to 4N where all right eyes are to receive a right eye perspective (first image) during a (first) time window and all left eyes are to receive a left eye perspective (second image) during a (second) time window, e.g. each multiplexing cycle comprises these two time windows - and the sum of the first time window and the second time window may define the length in time of the multiplexing cycle needed to generate the first image and the second image (not withstanding any blanking period for DC voltage balance).

[0536] For example, considering a display having modules with one module having for example 32 light modulators and for example two observers that are close enough to the display so that the angular resolution of viewing zones allows for directing separate images to each eye of an observer. As mentioned, the number of light modulators in a module is not necessarily 32. The number may be within previously mentioned ranges - it is independent of any specific embodiment. And in general, the modules may have different number of light modulators for all embodiments.

[0537] When a first column of light emitters behind a module emits light for generating a column of pixels for a first image there are two light modulators open (because of two right eyes in front of the display) and the rest of the light modulators are closed (30 closed), e.g. it may be exclusively the right eye of the first observer and the right eye of the second observer that is to see the first image (the first image is thus a right eye perspective of a scene). There is a ratio of open to closed light modulators of 2 / 30. Everywhere else than the right eyes does not receive any light (not withstanding any don’t care zones where there are no eyes).

[0538] After the first column of light emitters has emitted light in a first step in the multiplexing cycle a second column of light emitters emits light in a second step in the multiplexing cycle and so forth one step at a time. As mentioned for the solution in figures 4L to 4N the scan / addressing of the columns of light emitters is for example left to right.

[0539] The second column of light emitters has a different position than the first column of light emitters. Thus, as the second column of light emitters emits two other light modulators are addressed by the controller to be open so that the two right eyes also receives the light from the second column of light emitters. This continues one step at a time in the multiplexing cycle until the first image has been generated.

[0540] When the first image has been generated (all columns of light emitters has emitted light) a second image is to be generated (the left eye image being a left eye perspective). When a column of light emitters behind a module emits light for generating a column of pixels for the second image there are two light modulators closed (the ones that were previously open) and the rest are open (30 open). There is a ratio of open to closed light modulators of 30 / 2. It could be a higher number of light modulators that are closed in order to avoid cross talk or at least be certain that the right eyes are blocked for light representing a left eye image. This could in principle affect DC balance and require and blanking period after the first and the second time window or in between the two time windows.

[0541] Thus, during a multiplexing cycle for generating the two images the number of times that the light modulators were open is the same as the number of times they were closed. In this way a DC balance may be achieved over time without having to take a break for a blanking period to take place.

[0542] This means that when generating the second image the only zones that do not receive light are the two zones defined by the positions of the two right eyes. The display emits light to everywhere else, e.g. another observer than the two mentioned will see a left eye perspective for both eyes (a 2D image). Or vice versa, e.g. it could be that it is the right eye perspective that is emitted to all zones except the two zones defined by the two left eyes.

[0543] It is the same (physical) light modulators (and not just the number of light modulators) that during the first time window are open and during the second time window are closed. Similarly, it is the same (physical) light modulators (and not just the number of light modulators) that during the first time window are closed and during the second time window are open. In other words, by first running through a first sequence of patterns and then a second sequence of patterns on the light modulators, where the second sequence comprise reverse patterns of the first sequence, all light modulators will have been open and closed for substantially equal amounts of time and hence a DC will substantially be maintained. In general, when generating the two images (in two time windows during the multiplexing cycle) the ratio R1 of open to closed light modulators in the first time window is the inverse (1A(-1)) to the ratio R2 of open to closed light modulators in the second time window (R1 = R2A(-1) * (1+ / -10%)). There might be a slight difference of for example 10 % between the ratio in the first time window and the inverse ratio of the second time window.

[0544] The number of light modulators that are open each time a LED column emit lights during the multiplexing cycle is much greater in one of the time windows than in the other such as more than 32 / 2 times greater or at least 10 / 2 times greater.

[0545] The above takes place per module, e.g. if there are several modules they operate in parallel and send out light at the same time as also described in connection with the other embodiments of the present disclosure.

[0546] This scheme of controlling the light emitters and the light modulators may also be used in a case where the display comprises a LCD panel for generating the images and the light emitters does not generate the image but only send light through the LCD panel. In such a case each light emitter column may be replaced with a (vertical) light guide.

[0547] % sliding window with blanking period

[0548] Another scheme than the one with a ratio of open to closed light modulators in two time windows being R1 = R2A(-1) is contemplated. Specifically, that the number of open light modulators each time a light emitter column emits light during each time window is lower than 10, e.g. in each step in the multiplexing cycle there is no more than 10 light modulators open (per module if there are several modules). In such a case up to 10 light modulators may be open per step in the multiplexing cycle during the first time window for transmission of light to all right eyes. The rest of the light modulators in a module are closed / shields light to all other areas / zones than the right eyes.

[0549] And up to 10 light modulators may be open per step in the multiplexing cycle during the second time window for transmission of light to all left eyes. The rest of the light modulators in a module are closed / shields light to all other areas / zones than the left eyes. This means that for everyone else than the tracked observers the display will appear to be dark. A blanking period for DC balance of the light modulators may be necessary.

[0550] This scheme of controlling the light emitters and the light modulators may also be used in a case where the display comprises a LCD panel for generating the images and the light emitters does not generate the image but only send light through the LCD panel. In such a case each light emitter column may be replaced with a (vertical) light guide.

[0551] % Polarizers for sliding window

[0552] Between the light emitters and light modulators may be arranged a plurality of polarizers. The polarizers may be arranged so that there is one polarizer per line / row of light emitters. This means that light from a row of light emitters may be polarized according to the polarization of the polarizer in front of that line.

[0553] Thus, in front of all even rows of light modulators there is a polarizer with a first polarization, and in front of all odd rows of light modulators there is a polarizer with a second polarization. The first polarization may be linear. The second polarization may also be linear. The two polarizations may be orthogonal.

[0554] When the light modulators are in a closed state for the first polarization they may be open for the second polarization or vice versa, e.g. it either opens for one polarization and closed for another. And when the light modulators are in an open state for the first polarization they may be closed for the second polarization.

[0555] The light emitters on even rows are responsible for generating a first image such as a right eye image, and the light emitters on odd rows are responsible for generating a second image such as left eye image. Or vice versa. Thus, the light emitters are split in two “sets”. A first set for generating a first image, and a second set for generating a second image.

[0556] This can be used to generate the two images simultaneously, e.g. instead of having a first time window for the generation of the first image followed by a second time window for the generation of the second image.

[0557] All right eyes may then be tracked so it is ensured that the light modulators are controlled so that all right eyes only receive the right eye image - everywhere else receives the left eye image. This is the same scheme as explained above for the “Inactive viewing zone DC balance” section. It may be the other way around so that all left eye images are tracked. It may not necessarily be the eyes that are tracked but an observer and then it may be estimated by a controller where the eyes are.

[0558] As an example, the light emitters on even rows in a column of light emitters generate a pixel column of a right eye image. This light is polarized by the polarizers in front of the light emitters on even rows. The light modulators for all right eye viewing zones are controlled such that they are open and the light from the even row light emitters may be transmitted through. All other light modulators are in a closed state for the polarized light from all even rows of light emitters so that this light does not pass through.

[0559] The light from all odd rows of light emitters is polarized orthogonal to the polarization of the light from all even rows of light emitters meaning that light from all odd rows of light emitters is blocked by the light modulators that are open for the right eye viewing zones. On the other hand, all the other light modulators allows for the light from the odd rows of light emitters to pass through so that a left eye image is transmitted to all viewing zones except the right eye viewing zones, e.g. these light modulators are open with respect to the second polarization.

[0560] In general, two polarization directions may used to have four “states” when using a light modulator that when a voltage is applied to the light modulator it transmits a first polarization and blocks and second polarization, e.g. it has a complementary behavior with respect to the two polarizations illustrated in the below table.

[0561] The polarizers may be interchanged and the light emitters and light modulators controlled such that it is the left eyes that are tracked and receives a left eye image, and everywhere else receives a right eye image - no withstanding don’t’ care viewing zones mentioned below. The disadvantage of splitting the light emitters in two sets is that the vertical resolution of the display is halved. The advantage is that the multiplexing ratio is reduced. This may be used to increase the maximum viewing angle of the display.

[0562] Don’t care viewing zones / light modulators may be used in this scheme for the DC balance, e.g. a suitable number of don’t care light modulators may be identified and set to either open or closed state depending on their DC balance.

[0563] % Fig. 5: three neighboring LEDs emitting light + diffuser

[0564] Fig. 5 is a close up of the set of LED columns 13 and the diffuser 3.

[0565] The diffuser may be selected or configured so it essentially closes dark gaps between LEDs, e.g. it may spread light from illuminated neighbouring LED columns behind it so an essentially uniform vertical stripe is observed from the front. This may increase the horizontal uniformity of the vertical stripe hence ensuring that light observed through the light valve column has a centroid close to the centre of the light valve column, further ensuring a regular grid of observed pixel centroids which may result in better image quality.

[0566] The diffuser may be selected or configured to close gaps while not spreading light so much that there is too much spill over unto dark neighbouring LED columns, since this spill light might be observed by another eye not intended to observe it, creating crosstalk between for example the first image and the second image.

[0567] Hence, a balance between closing gaps and light spill may be found for a desired compromise between a regular pixel grid and low crosstalk. Such a desired compromise may be found for example by trying a number of diffusers with different degrees of diffusion and selecting the preferred compromise. For example, the diffuser may have a point spread function with a full width-half maximum fall-off radius of for example equal to a centre distance between LEDs. To improve this compromise a diffuser with a batwing light distribution may be selected. Alternatively, or additionally a pattern of varying neutral densities (not shown) configured so it eliminates or reduces brightness variations on the diffuser 3 may be comprised. The pattern may essentially be a reverse (e.g. negative) reproduction of the brightness variations on the diffuser 3 as observed from the front, e.g. from the side facing towards to spatial light modulator 1. The pattern may for example be printed on the diffuser 3. If the diffuser 3 has a structured and a flat side, that pattern may be printed on the flat side. Alternatively, the pattern may be printed on a transparent sheet which may be laminated onto the diffuser 3.

[0568] % Fig. 6: diffuser far from LEDs

[0569] Fig. 6 shows an alternative configuration, where the diffuser 3 is located with a large distance the LED array 2.

[0570] The distance may be large enough so that a spot created from an LED is large enough to fill out a light valve column as observed from an observing eye located within a desired observation distance range with light not varying more over the width of the light valve column than a maximum allowed brightness variation, for example 20%. The distance between the diffuser 3 and the LED array 2 may be calculated with well-known geometry using a radiation angle of an LED, a diffuser full width-half maximum, a width of a light valve column and a minimum and maximum viewing distance. For example, LEDs may have a radiation angle of 45 degrees full width-half maximum and the distance between the diffuser 3 and the LED array may be 1.5 times a width of a light valve column. An advantage of this configuration is that during the interval only one LED column per eye needs to be flashed, which may reduce requirements to the speed of driving circuits for LEDs.

[0571] Some measures may be taken to improve light efficiency. For example, a first lens array of vertical cylinder lenses having a pitch essentially equal to the pitch of the LED array may be comprised located in front of or behind the spatial light modulator 1 with cylinder lenses positioned having vertical centre lines essentially coinciding with vertical centre lines of light valve columns. A lens in the first lens array may be configured with a focal length equal to a distance to an LED directly behind said lens. Additionally or alternatively, a second lens array of cylinder lenses may be comprised in front of the LED array 2 with a lens centre positioned essentially over LED centres. A lens in the second lens array may be configured so it radiates light in a range of angles corresponding to a range of desired viewing angles for the disclosed display.

[0572] % don’t care DC balance

[0573] The tracking system may be used to determine any don’t care viewing zones / don’t’ care liquid crystal cells / light valve columns. The set of don’t-care light valve columns may be calculated using a set of positions of LEDs which are flashed during when a liquid crystal cell is open and a set of positions of observing eyes, so that essentially none of the observing eyes will observe light from LEDs flashed if any of the light valve columns in the set of don’t-care light valve columns are opened by the controller 9, e.g. a don’t care light valve may be identified as a light valve that is in the path defined by the line of sight between a LED column emitting light and the eye of an observer - the eye that is not supposed to receive any light.

[0574] The processor 9 may open the set of don’t-care light valve columns or a subset hereof and it may shorten the duration of the blanking interval with an amount of time essentially equal to the number of opened light valve columns in the don’t care set times the duration. An advantage of this configuration is, that it may increase frame rate and brightness of the disclosed display. The controller may calculate the don’t care set, so a DC offset balance over the liquid crystal cells over an interval Tic is kept essentially at zero volt. Tic may for example be one second.

[0575] For example, if a liquid crystal cell has been in a closed state for a period of time such that there is a DC voltage offset (voltage different from zero) across that cell the controller may determine based on input from the tracking system if it is possible to open that cell for obtaining a DC balance for the cell. It will be possible to open a cell if cross talk can be avoided, e.g. light is emitted through the cell to a don’t care viewing zone.

[0576] Thus, in that situation a first liquid crystal cell is open for transmitting light to an active viewing zone such as an eye of an observer, a second liquid crystal cell is closed for preventing cross talk in an inactive viewing zone such as the other eye of the observer, and a third liquid crystal cell is open for reducing a DC voltage offset in that cell, e.g. the third liquid crystal cell is identified as a liquid crystal cell that when it is open while the first liquid crystal cell is open and the second liquid crystal cell is closed light is transmitted to a don’t care viewing zone - said in other words, the third liquid crystal cell constitutes a don’t care liquid crystal cell.

[0577] With the term “offset” is meant that the DC voltage across the cell is different from zero or has been different from zero in a period of time, for example 1 second or up to 10 or 20 seconds. If there is a DC offset for too long a time the cell may become defect. How long time that it may depend on the crystals and the age of the display or how the display has been used. % Fig. 7: a display with modules

[0578] Fig. 7 shows an arrangement of a modular display where several displays / modules according to the disclosed invention, below referred to as display modules, may be “assembled” to form a larger display.

[0579] It is contemplated that each (liquid crystal) module may comprise a set of at least eight liquid crystal cells (spatial light modulators) or comprise a number of liquid crystal cells in the range 8 - 80 liquid crystal cells, such as 20 - 40 liquid crystal cells. In practice it is contemplated that a set has 30 or 32 liquid crystal cells.

[0580] Display modules may have essentially equal light valve column pitch, e.g. a light valve column pitch of a first display module may be equal to a light valve column pitch of a second display module, where pitch meaning a centre to centre distance of light valve columns.

[0581] Display modules may be assembled so a first light valve column located as the rightmost light valve column in a first display module is located adjacent to a second valve column located as the leftmost light valve column in a second light display module with a distance from a centre of the first light valve column to a centre of the second light being essentially equal to a pitch of a light valve column pitch of the first and second display module. In other words, spatial light modulators in the display modules may be arranged so essentially all light valve columns in the larger display have equal pitch.

[0582] Spatial light modulators in the display modules may be located on a glass substrate holding light modulators for several display modules, for example there may be a single glass substrate for the larger display holding light modulators for all display modules. In this arrangement LED arrays may have same width and height as spatial light modulators, hence LED arrays can also be assembled adjacently, so LEDs in the larger display have equal pitch horizontally and vertically. In other words, LEDs of assembled display modules may form one large LED array.

[0583] LED arrays may be mounted on a single PCB for the larger display or on separate PCBs, for example one PCB for each display module, physically assembled precisely enough together for LEDs to form one larger array. Technologies for such precise assembling are well known in the art of LED video walls, LED digital signage and micro LED displays. Display modules may share LEDs, e.g. an LED in a first display module may be flashed to illuminate an observing eye through a light valve column in a second display module.

[0584] In an especially advantageous configuration, LEDs in the above description may be replaced by directional light emitters, having a vertical angular resolution, e.g. capable of emitting light in a number of horizontally elongated viewing zones at different vertical angles. Such directional light emitters may be configured according to well-known art of directional pixels, for example each directional light emitter may comprise a set of LEDs located behind a focusing such element, such as a lens.

[0585] For example, the directional light emitters may be capable of emitting light in two different directions, a lower viewing zone and an upper viewing zone. In this case, each light emitter may comprise two LEDs and these two LEDs may be comprised in a passive matrix driving circuit.

[0586] An advantage of this configuration is that it has both a horizontal and a vertical angular resolution, and for example, if the display is located in a living room, a first image may be sent to a first observing eye belonging to a person sitting on the floor and a second image may be sent to a second observing eye belonging to a person sitting in a sofa, where said first and second image may be different, even if said first and said second observing eye are located on a same vertical.

[0587] The modules are controlled (by one or more controllers) such that they operate in parallel.

[0588] In the example the display comprises five “modules / segments”. This can be seen, because it is illustrated that five columns of light are emitted to each viewing zone.

[0589] Each module operates as described in connection with fig. 4, but the image is also divided into “parts”, e.g. a first module is responsible for generating a first part of the image, and a second module is responsible for generating a second part of the image etc.

[0590] Each module has one liquid crystal cell open at a time - with five modules this means that five columns of the image are generated at a time and directed to the observer. Similarly, each module has one light emitter column (it may be a plurality of adjacent light emitter columns to ensure an aperture is filled with light) that are scanned and flash light, e.g. in the example five light emitter columns are scanned to emit / flash light.

[0591] The modules may be scanned independently from each other, e.g. one module may have a scan sequence that scans the liquid crystal cells one after the other from left to right and another module may have a scan sequence where the crystal cells are scanned at random one after the other.

[0592] The modules may be controlled by the controller of the display such that at a point in time during a multiplexing cycle at least 80 %, such as 90 %, of the modules have a liquid crystal cell in the light transmitting state, e.g. the modules are controlled in parallel.

[0593] A first module may be scanned as a function of the scanning of a second module and the position of an observer / viewing zone, e.g. a set of liquid crystal cells may have a scanning sequence depending on the scanning sequence for a set of liquid crystal cells for another module. Similarly, a set of LED columns may have a scanning sequence depending on the scanning sequence for a set of LED columns for another module.

[0594] The number of LED columns is preferably to be higher than the number of liquid crystal cells in a module, e.g. the width of the area occupied by the LED columns is greater than the width of the area occupied by the liquid crystal cells. Thus, there is an overlap between the LED columns that are used by two sets of liquid crystal cells. Thus, an aperture in a first set of liquid crystal cells may be illuminated by a certain LED column, and that LED column may also flash light for illuminating another aperture (in another module), e.g. two sets of liquid crystal cells share a number of LED columns. It also means that the total width of all LED columns is greater than the total width of all the liquid crystal cells - the disclosed display can be recognized by a bezel (one way to visually distinguish between the disclosed display and a lenticular display or a parallax barrier display.

[0595] The example illustrates two viewing zones (rays for the right eye and rays for the left eye). Thus, during the time interval T (in which a liquid crystal cell in each of the modules has been selected to be open) the light emitters (in each module) that are in a position such that light will reach the right eye are scanned such that they flash light and afterwards (within the same time interval T) the light emitters (for each module) that are in a position such that light will reach the left eye are scanned such that they flash light.

[0596] However, in the case of the display having an active matrix addressing scheme (with a memory component, such as a sample and hold circuit for each light emitter column) a light emitter column for each viewing zone is scanned / addressed for turning it on such that a plurality of light emitter columns end up emitting light at the same time. When the last light emitter column has been turned on they are all turned off collectively, e.g. at the same time before proceeding to the next liquid crystal cell in the scanning sequence.

[0597] It may be that a viewing zone is at a sharp angle, e.g. an observer is positioned to the side of the display. This means that during a multiplexing cycle two neighboring modules (first and second module) may be controlled such that it is necessary that a liquid crystal cell of the second module is in a light transmitting state for transmitting light from a LED column of the first module.

[0598] % Fig. 8: active matrix display

[0599] Fig. 8 shows an example of an active matrix addressing scheme.

[0600] Compared to the passive matrix addressing scheme described above in connection with fig. 4, all sets of LED columns for the number of (active) viewing zones (in this example four viewing zones) are emitting light substantially at the same time, e.g. there is a time interval (for example 1 / N of a multiplexing cycle, where N is the number of liquid crystal cells in a module) in which all four sets of LED columns emit light - the time interval where a liquid crystal cell is open.

[0601] Substantially means that one LED column may be about to turn off while the other are about to turn on.

[0602] The LED columns to be on when a liquid crystal cell is open is scanned in sequence, e.g. one after the other while data is provided in data lines to each LED and read into the memory component of the driver circuit (sample-and-hold register for example) for each LED. Thus, the LED columns turn on one after the other and when the time interval has passed all of them are closed substantially at the same time.

[0603] In the example the set of LED columns comprise three LED columns for each viewing zone (in order to fill out the aperture with light). Thus, there are 4 x 3 LED columns that are on. When they are “turned off” the off-signal is provided on the 12 select lines connected to these LED columns while the data-lines are set to zero.

[0604] A disadvantage of an active matrix addressing scheme is that in practical implementations, an active matrix display is usually manufactured in thin film and this sets limits to how bright the display can be.

[0605] % Figs. 9a and 9b: double FLCD

[0606] Figs. 9a and 9b show the disclosed display with two liquid crystal layers, e.g. there is an additional layer of liquid crystal cells.

[0607] The additional layer 14 is arranged between the light emitters and the layer with the scanning apertures, e.g. the layer described in connection with fig. 4 for example.

[0608] The purpose of the additional layer is to avoid crosstalk, e.g. the liquid crystals cells of the aperture layer may transmit some light even when they are in the blocking state, which creates crosstalk.

[0609] The purpose of the liquid crystal cells in the additional or second layer is not to focus and delimit the light from the light emitters as in the “first” aperture layer.

[0610] The liquid crystal cells in the additional layer are also scanned in a sequence during the multiplexing cycle. The sequence or selection of each liquid crystal is a function of the liquid crystal cell that is open in the first aperture layer, and the viewing region / zone / an- gle with respect to the display that the generated image is visible at.

[0611] A set of liquid crystal cells is selected in each step of the multiplexing cycle - there may be more than one liquid crystal cell selected.

[0612] Fig. 9b is a more simple implementation where the number of liquid crystal cells that are open in the additional layer is a function of the viewing angle of the display and not the specific viewing zone as in fig. 9a.

[0613] The viewing angle of a display is the maximum angle at which the display can be observed with acceptable visual performance. This means that a higher number of liquid crystal cells in the additional layer are open compared to the implementation described in connection with fig. 9a. The disadvantage is that crosstalk may not be reduced to the same degree as for fig 9a.

[0614] An even more simple configuration may be to make each liquid crystal cell in the additional layer wider compared to the width of a liquid crystal cell in the aperture layer. Such a wider configuration can also be achieved by controlling neighbouring liquid crystal cells such that for example two or three or four neighbouring liquid crystal cells are open substantially at the same time.

[0615] % Fig 9c: DC balance for double FLCD

[0616] The blanking period (for the light modulators / FLCDs) may be reduced or even removed for a display comprising two light modulator layers, e.g. double FLCD implementation.

[0617] This may be done by switching between which light modulator layer is closed for blocking light from a light emitter emitting light for reaching an unintended viewing zone (which could cause crosstalk).

[0618] In fig. 9c the light modulators are scanned / updated from left to right for opening one light modulator at a time. As mentioned, this gives an aperture that moves from left to right one step at a time, e.g. the next light modulator to open is the neighbour to the right of the light modulator that is open. This is the same scan sequence of the light modulators as in figs. 4a-d.

[0619] Another scan sequence may be contemplated as long as each light modulator has been open once during the multiplexing cycle as mentioned. When using the light emitters and light modulators as a directional backlight for a LCD panel each light modulator will have been open twice, e.g. the light modulators are scanned / updated from left to right twice during a multiplexing cycle - one time for each image that the LCD panel generates. The reason for why this double scan is necessary is that the LCD panel cannot be updated fast enough (at least not standard commercially available LCD panels in year 2024). Thus, in the directional backlight use case fig. 9c only shows half of a multiplexing cycle. Fig. 12c on the other hand shows a full multiplexing cycle and half of a second multiplexing cycle. A light emitter emits light through the open light modulator. As mentioned, which light emitter that emits light depends on the position of the active viewing zone. This may be referred to as a “hybrid scan” scheme in contrast to a “sliding window scan” where the light emitters are scanned one step at a time from left to right or from right to left (or in general in a sequence independent of observer position).

[0620] In fig. 9c the two light modulator layers are shown at their respective states during a multiplexing cycle. The time axis is downwards in the page. A state of a light modulator (in a logical module) defines which light modulators are open and which are closed. Closed is shown with black and open is shown with white. Since there are 32 light modulators that are 32 states during a multiplexing cycle (64 states when the double light modulator is used in a backlight for a LCD panel). This is the case both where there is only one light modulator layer and when there are two. If there is another number of light modulators in a light modulator layer the number of states corresponds to that number.

[0621] In the example one light modulator in the light modulator layer closest to the light emitter is open - it may be a number of neighbouring light modulators that are open for transmitting light to an active viewing zone as also explained elsewhere in the disclosure. An open light modulator is illustrated as white, and a closed as black. In the figure the light emitters are contemplated to be arranged at the top of the page, e.g. the light modulator layer with the least number of open light modulators is between the light emitters and the other light modulator layer, but it may also be the other way around.

[0622] Likewise, in the second light modulator layer there is also a light modulator open (or a number of neighbouring light modulators are open) such that light that has been transmitted through the light modulator(s) open in the first light modulator layer may be transmitted through the second light modulator layer to the active viewing zone.

[0623] The number of open light modulators in one layer for transmitting light to an active viewing zone may be greater than in another layer as also mentioned above in connection with figs. 9a-b.

[0624] In fig. 9c there are a greater number of open light modulators in the second layer than in the layer closest to the light emitters, e.g. 1 light modulator is open in the layer closest to the light emitters and 3 neighbouring light modulators are open in the other layer. On both sides of the open light modulator in each light modulator layer there are a number of light modulators closed for blocking light from the light emitters that emits light (in the respective step in the multiplexing cycle).

[0625] Thus, there is a number of columns aligned with each other in the two light modulator layers that are closed at the same time. With aligned means that it is the same columns of light modulators in the two layers that are closed, e.g. they have the same columns numbers / horizontal coordinates (they are in the same vertical plane that also comprises the normal to the display). Thus, when observing the display at a line of sight parallel to the normal of the display two aligned light modulators are arranged such that one is in front of the other.

[0626] This number may define a first set of light modulators in a light modulator layer at a step in the multiplexing cycle (could be termed a closed / closed set). There is such a set on each side of the open light modulator, so four sets in total per logical module. This gives a good contrast. In fig. 9c there are 5 light modulators in the closed / closed set. But it may be a number in the range 1 to 20, or 1 to 15, or 1 to 10, or 1 to 5 or 2 to 20, or 2 to 15, or 2 to 10, or 2 to 5.

[0627] T o the right of the light modulators defined by the first set is a number of light modulators that are open in one of the light modulator layers. This number defines a second set of light modulators at a step in the multiplexing cycle, could be termed a closed / open set), because these are aligned with light modulators in the other layer that are closed. And the double light modulator layer is in what could be termed a semi-transparent state for DC voltage balance of the light modulators. In fig. 9c the open light modulators belonging to the second set are arranged in the light modulator layer furthest away from the light emitters. In fig. 9c there are 8 light modulators in the closed / open set. But it may be a number in the range 1 to 20, or 1 to 15, or 1 to 10, or 1 to 5 or 2 to 20, or 2 to 15, or 2 to 10, or 2 to 5, or 3 to 20, or 3 to 15, or 3 to 10, or 3 to 5.

[0628] To the right of the light modulators of the closed / open set follows another closed / open set of light modulators but the open light modulators are now arranged in the other layer than for the previous closed / open set. Thus, it alternates which light modulator layer the light modulators of the second set are arranged in. Between each set of closed / open light modulators there is illustrated one light modulator that is closed in one light modulator layer and aligned with a closed light modulator in the other light modulator layer. This may define a transition from one closed / open set to another, and it may be omitted.

[0629] Fig. 9c illustrates a total of 32 light modulators (in each light modulator layer) - it may be one logical module of a double layer of light modulators.

[0630] 9 light modulators are open in the light modulator layer closest to the light emitters. 2 more are open in the other layer. Thus, this gives a ratio of 9 / 32 of open to closed light modulators.

[0631] A light modulator that is open in the above scheme / scanning may be applied a voltage that is X times greater than the (absolute) value of when it is closed, in other words numerically X times greater and having the opposite sign. X could be found from the DC balance:

[0632] DC balance = N_open*X*V_close - (N_total-N_open)*V_close = 0 where N_open is the number of open light modulators at a time (in a light modulator layer).

[0633] Meaning X = (N_total-N_open) / N_open

[0634] In the example this would be that X is (32-9) / 9 = 2.5 times greater. Thus, if the close voltage is V_close = -5 V then the open voltage would be V_open = -2.5*(-5) = 12.5 V.

[0635] It should be noted that the DC balance does not have to be achieved per multiplexing cycle. So for example, two multiplexing cycles could be used for achieving the DC balance meaning that X could be half. In the example this would give X = 1.25 (when using two multiplexing cycles to achieve the DC balance).

[0636] % T ransient voltage

[0637] There may be a transition period with a transient voltage V_trans between an open voltage, and the close voltage, e.g. there may be an overshoot applied when changing the voltage from an open voltage to a close voltage. The period may be in the range 2 to 20 microseconds, such as 2 to 15, or 2 to 12 or 2 to 10, or 4 to 20, or 4 to 15, or 4 to 12 or 4 to 10.

[0638] The overshoot / transient voltage may have an absolute value with a maximum that is greater than the absolute value of the close voltage, such as more than 10 % greater: max(abs(V_trans) > f * abs(V_close) where f is a factor such as f = 1.1 (when it is 10 % greater). It may also be more than 20 %, or 25 % or 50 % or more than 100 % greater.

[0639] For example, the transient voltage may go down to -10 V, e.g. having an absolute value with a maximum of 10. This means that the voltage as a function of time at discrete points in time would be ... 12.5, -10, -5,... , 12.5,... , -10. -5,...

[0640] % Fig. 10a - c: view crash

[0641] Fig. 10a - c shows how view crash may be avoided.

[0642] The modules of the disclosed display introduces a risk of view crash (part of an image intended for a first viewing zone is visible in another viewing zone where it should not be visible).

[0643] The number of liquid crystal cells in a module may be a function of the brightness of the light emitters, e.g. choosing light emitters with high brightness can reduce the risk of view crash, because there can be a higher number of liquid crystal cells in a module.

[0644] There is a trade off between loss of brightness and risk of view crash - the higher the number of liquid crystal cells in a module the lower brightness, and the lower the liquid crystal cells the higher the risk of view crash. The number of liquid crystal cells in a module is a balance between the risk of view crash and loss of brightness.

[0645] Fig. 10a shows a display with 8 modules.

[0646] Four eyes are observing the display. The modules are scanned in parallel such that each module has one open liquid crystal cell thereby creating a number of light pattern (8 in the example) that are emitted from the display.

[0647] As can be seen light from an LED in one module can escape through an open liquid crystal cell in another module, e.g. there is a module “responsible” for the view crash, because it has a liquid crystal cell open, and there is a “original” module from where the light pattern has been emitted.

[0648] Fig. 10b shows a display with 16 modules.

[0649] In this example one of the eyes receives an unintended light pattern and there is a view crash.

[0650] Such a view crash may be determined by a tracker and the controller, e.g. the tracker informs the controller of the position of the observing eyes (active viewing zones). The tracker may also track the number of observers - or at least up to a certain number of observers. For example, the display may be configured to display 3D content to a number of observers, and when that number of observers exceeds a threshold, such as 4 or 5 or 6 or 7 or 8 or 9 or 10 observers, the display switches from displaying 3D to displaying 2D to either all observers or only to the observers above the threshold, e.g. a first number of observers still observers 3D content, but the remaining observers observes 2D content.

[0651] The display is to direct the images to the intended viewing zones so starting with a first eye the multiplexing cycle may be defined for example by scanning one liquid crystal cell after the other one by one in a consecutive sequence and scanning the needed LED columns one by one starting with the LED column for a first active viewing zone.

[0652] Thus, the controller knows which liquid crystal cells are open in each module and which LED columns are selected in each module. The controller can therefore determine if there will be a view crash before it happens.

[0653] In fig. 10c is illustrated that the view crash has been avoided. A solution for avoiding a view crash may be to change the scan sequence of the liquid crystal cells of the module responsible for the view crash.

[0654] A specific solution could be that if originally a scan of liquid crystal cells from right to left in the responsible module leads to the view crash the scan sequence could be change so that the liquid crystal cells in the responsible module are scanned from left to right. It could also be the other way around, e.g. that the scan sequence of the liquid crystal cells in the “original” module is changed.

[0655] Any change in scan sequence of liquid crystal cells of a module is adequate as long as the view crash is avoided, it could also be that two elements (liquid crystal cells) in the scan sequence are interchanged in one of the modules.

[0656] In general, to avoid view crash the scan sequence of the liquid crystal cells of the responsible module is changed depending on the scan sequence of the liquid crystal cells of the original module or vice versa.

[0657] % Figs. 11a - c: modular display with two layers of FLCD

[0658] Figs. 11a - c also show a modular display as shown in fig. 7 and with two layers of liquid crystal cells as shown in figs. 9.

[0659] The display has two modules and there are four active viewing zones (two observers observing 3D content).

[0660] Light patterns are illustrated as being emitted at the same time, e.g. as in an active matrix display (also shown in fig. 8) where columns are selected one by one and emit light until they are de-selected simultaneously.

[0661] However, the fig. should not be understood as being limited to active matrix displays, but rather show how light is emitted also for a passive matrix display - where one column at a time in each module flashes light.

[0662] The figures (fig. 11a-c) show a sequence (on the same page) of how each aperture in the two modules “moves” and has three different positions (a different position in each figure) and how different columns are selected and emit light. The above figures have illustrated how a module may be operated and how a plurality of modules operates in parallel (or substantially in parallel), and how the aperture layer and light emitter layer works as a stand alone display.

[0663] % Fig. 12a: backlight solution

[0664] In the following it will be disclosed how this stand alone solution can be used as backlight for a LCD panel and in that way achieve a 3D or multiview display.

[0665] As mentioned, for a backlight solution the LCD panel may either be placed in front of the light modulators or it may be placed between the light emitters and the light modulators.

[0666] In that solution the aperture may still define the pixel width, but the pixel height is then determined by the LCD panel and not the light emitter layer. The hybrid scan display still emits images - the only difference is that it is purely white uniform images that are generated - which the LCD panel then modulates.

[0667] It has also been described above that when the aperture is at a position a number of (light emitter) columns flash light depending on the number of viewing zones, e.g. for each aperture position is jumped back and forth between columns emitting light for directing light towards the active viewing zones. This is based on the assumption that the light emitters may be switched / updated faster than the liquid crystals. However, for a display having a maximum number of active viewing zones (such as no more than 6 active viewing zones for supporting a “3D look around” experience for three observers for example) it may be that it is the aperture that “jumps” around, e.g. the image parts for the images to be displayed to the active viewing zones are still interleaved but instead the same column flashes light a number of times corresponding to the number of active viewing zones - a different light pattern is emitted with each flash (if it is to be look around - if it is only to be 3D the same light pattern is flashed to all the right eyes and the same light pattern is flashed to all the left eyes) and for each flash there is an aperture position such that the flash is visible in the desired active viewing zone.

[0668] Fig. 12a shows a top view of a configuration where the Hybrid Scan Display is used as a directional backlight, specifically for a time division multiplexed LCD panel 15.

[0669] This may achieve a multiviewer or autostereoscopic display having a higher resolution and / or larger color gamut than compared to when the Hybrid Scan Display operates as a stand alone display, because the LCD panel may have a higher resolution than a microLED panel.

[0670] Typically, a LCD panel comprises liquid crystals sandwiched between a pair of electrode substrates, and a polarizing film.

[0671] A standard commercially available LCD display may be used and have its backlight removed and replaced with the hybrid scan display as backlight for the LCD panel 15.

[0672] The LCD panel 15 may be operated so it alternate between a left eye time slot, in which it shows a left eye perspective image and a right eye time slot, in which it shows right eye perspective image.

[0673] Fig. 12a shows the configuration in a right eye time slot.

[0674] The Hybrid Scan Display may be synchronized to the LCD panel so it illuminates a set of left eyes in an audience when said left eye perspective image is being shown and so it illuminates a set of right eyes in an audience when said right eye perspective image is being shown.

[0675] For example, the Hybrid Scan Display may show a uniform white image or a backlight dimming zone image for a left eye image when the LCD panel shows a left eye perspective image and the Hybrid Scan Display may show a uniform white image or a backlight dimming zone image for a right eye image when the LCD panel shows a right eye perspective image. Hence left eyes in the audience will see the left eye perspective image and right eyes in the audience will see the right eye perspective image, and members in the audience will see the same stereoscopic image.

[0676] The LCD panel 15 may be operated in a frame tripled, strobed mode, so that each image being scanned-out three times by the panel but only the third time the backlight is active, giving time for the liquid crystal cells to respond to update values before the backlight is active.

[0677] The LCD panel 15 may for example be operated at 360Hz and have a pixel response time from 0% to 80% gray being less than 2.5ms and a pixel response time from 80% to 0% gray being less than 2.5ms. The LCD panel may for example be a ZOWIE XL2566K monitor from BenQ eliminated it’s original backlight.

[0678] An input sequence to the Panel 15 may for example be: L1 , L1 , L1 , R1 , R1 , R1 , L2, L2, L2, R2, R2, R2, where L1 and L2 are left eye perspective images and R1 and R2 are right eye perspective images. After completion of the first scan-out of the L1 image, all liquid crystal pixel cells will substantially be updated with a voltage across their electrodes corresponding to pixel values in L1. After completion of the second scan-out of L1 all liquid crystal pixel cells will substantially have reached their target values, since the scan-out will have a duration of equal to or less than 1 / 360Hz = 2.8ms, which is longer than the response times of 2.5ms. Hence when the third scan-out of L1 begins, all pixel cells have substantially reached their target values and they will remain at these during the third scan-out, and the backlight may then be active during the third scan-out. The same procedure may be applied for updating images R1 , L2, R2 etc. Hence, there will be substantially no crosstalk between left and right eye perspective images due to pixel response times.

[0679] Alternatively, the backlight may be divided into a number of sections which are active in different intervals, synchronized with intervals in which liquid crystal pixel cells of the LCD panel have reached their target values. For example, the backlight may divided into a first section located behind a first half part of the screen which is being updated first during a scan-out and a second section located behind a second half part of the screen which is being updated after the first half part. The first section may be active during the second half of the scan-out of the second L1 and during the third scan-out of the third L1. The second section may be active during the third scan-out of L1 and during the first half of the scan-out of R1. In this configuration the interval during which the first section and the second section are active may be 50%. The first and second sections may be Hybrid Scan Displays arranged horizontally and the scan-out direction of the Panel 15 may be horizontal. A blanking interval Tb of a Hybrid Scan Display in this configuration may be synchronized with the intervals described above in which the Hybrid Scan Display is not active.

[0680] In general, the hybrid scan display and LCD panel are synchronized such that when a column of liquid crystal of the LCD panel have been scanned / updated such that the crystals in that column are at their target values / intended values, or at least close to that, such as 80 % updated, the moving aperture is controlled / scanned such that it is behind an updated column and the light emitters of the backlight are selected such that light travels to active viewing zones. For example, for a right eye image all right eyes receive light first whereafter a left eye image is generated in the LCD panel and all left eyes receive light. Specifically, an area forming a vertical band on the LCD panel 15 to the right of an active scan line may be illuminated, so pixels / crystals of the LCD panel are illuminated just before they are updated to a new value.

[0681] It may be arranged such that the moving aperture follows the movement / scanning of the LCD panel, e.g. the LCD panel may be scanned from left to right and so the aperture may move left to right such that has it moves along it is behind an updated column in the LCD panel. In general it does not have to be left to right it could be any movement as long as the whole image will be displayed.

[0682] The illustrated LED array 2 in the example may comprise white LEDs, since the Hybrid Scan Display in this configuration only functions as a directional white backlight for the LCD panel 15, which may comprise a color mask.

[0683] The illustrated diffuser 3 in the example may be selected or configured so it performs enough diffusion of light in both the horizontal and vertical direction to essentially eliminate visual dark gaps between LEDs, hence eliminating or reducing moiree patterns caused by interference between such dark gaps and a black matrix and / or color mask in the LCD panel 15.

[0684] Further, the light modulator 1 / liquid crystal cells and the additional light modulator 14 may be configured, so they have no or little periodic opaque mechanical structures, such as black matrix, periodic spacer structure or other mask, hence eliminating or reducing moiree patterns caused by interference between such opaque structures and a color mask and / or black matrix in the LCD panel 15. Gaps between light valve column electrodes in the light modulator 1 and in the additional light modulator 14 may be minimized in order to reduce light leakage in the absence of a black matrix.

[0685] With gaps between electrodes minimized, the width of a scanned area on the light modulator 1 , e.g. an area scanned during a multiplexing cycle, is determined substantially by the number of light valve columns scanned multiplied by the width of a light valve column, and the number of LED columns is determined by the width of a scanned area, the distance between the light modulator 1 and the LED array 2 and a desired angular resolution of the display. For example the number of light valve columns scanned may be 32 and the width of a light valve column may be 1 mm as in the above example, the distance between light valve columns substantially zero and the horizontal pitch of the LED array 0.5mm.

[0686] The horizontal resolution of the backlight (Hybrid Scan Display) is thus determined by the pitch of the LED array and the display size, and can be smaller than the horizontal resolution of the LCD panel 15, thus making manufacturing of the LED array 2 easier.

[0687] The resolution in the vertical direction of the LED array 2 can be much smaller than the vertical resolution of the LCD panel 15. For example, all LEDs in one column may be controlled so they always have essentially the same brightness value, hence the LED array has an effective vertical resolution of one pixel (having a very high rectangular shape, stretching from top to bottom). This is different from the stand alone hybrid scan display where a column in the LED layer comprises a plurality of light emitters in order to generate a column of the image, e.g. generate the vertical pixels of an column of the image to be displayed.

[0688] Alternatively, neighboring vertically aligned LEDs may be grouped into vertical groups of LEDs forming vertically elongated “pixels” controlled so they operate essentially identically. Such vertically elongated pixels may be used to form dimming zones for enhancing the contrast of the LCD panel 15; dimming zones and algorithms for calculating brightness of these being well known in the art of LCD displays.

[0689] In a right eye time slot, only right eyes of an audience should be illuminated, no left eyes should be illuminated from any part of the display, and vice versa, since crosstalk would then be experienced.

[0690] The additional light modulator / aperture layer 14 may be configured to select liquid crystal cells for opening, which are not in the path of undesired light rays. Hence, the additional light modulator 14 may be configured to assist in eliminating undesired illumination of eyes by shielding light rays in undesired directions, e.g. light rays towards a viewing region / angle which the generated image should not be visible at. This has also been explained above in connection with fig. 9 which shows an example of the hybrid scan display comprising an additional layer of crystal cells. Consider for example fig. 12a where an LED column 13 is being flashed to illuminate a right eye 5 of a first observer, with a first light ray here shown as a gray line. Without the additional light modulator 14 configured as described, LED column 13 would also send a second light ray, shown here as a dotted line, towards a left eye 6 of another observer, causing crosstalk to be experienced. With the additional light modulator 14 configured to select liquid crystal cells for opening, which are not in the path of undesired light rays, the additional light modulator 14 would have a closed liquid crystal cell in the path of the second light ray, substantially blocking it and eliminating or reducing crosstalk at left eye 6.

[0691] The additional aperture layer as well as the diffuser are as such not necessary, but may be used to achieve greater image quality.

[0692] % Fig. 12b: update scheme of LCD panel

[0693] When the light emitters and light modulators are used as backlight for a LCD panel it should be ensured, that pixels on the LCD panel are illuminated when they have reached their target values and not when they are transitioning from one pixel value to another. Since the backlight may be configured as logical modules of light emitters and light modulators, where the modules each operate an individual update cycle of apertures and / or LED columns scanning horizontally, the LCD display cannot in this configuration be updated as a typical LCD panel: from top to bottom. Instead it must be updated horizontally preferably in patterns substantially matching the backlight update scan sequences.

[0694] Further, to ensure that no LCD panel pixels in transition are illuminated, it must be considered, that a backlight module, when scanning columns close to neighbour modules, may emit light also through LCD pixels not only in areas af the LCD panel directly in front of it, but also in areas in front of neighbouring modules, because there will be some distance between backlight and LCD panel because of glass substrate thickness. This is ensured by having a scan sequence start in a horizontal position on the LCD panel which is a minimum distance away from a scan position where the subsequent scan sequence ended.

[0695] Fig. 12b illustrates an update scheme for the LCD panel. Each column of the LCD panel is in the graph represented as a square with the letter “R” or the letter “L” inside. The letter R refers to the pixel drivers of the pixels in a respective column are updated with the pixel values for a right eye image. The letter L refers to the pixel drivers of the pixels in a respective column are updated with the pixel values for a left eye image.

[0696] Only one letter is used to represent a whole column of pixels in the LCD panel meaning that all these pixels are updated with values of an image, but the specific value for a specific pixel in a column is not visible in the illustration.

[0697] The colours follow each other in time according to the following.

[0698] Starting with blue colour this shows when values are written into the pixel drivers of the columns.

[0699] Then red colour shows that the liquid crystals in the columns are in transition states, e.g. orienting themselves to the applied voltage. This may take some time which is why when pixel values have been written into the pixel drivers (blue) then that column is red for the next 6 time steps. In comparison this number was 3 for the scheme in fig. 12a. And in general, the lag / response time of the LCD panel depends on the specific LCD panel used. So instead of 6 it could be 2 or 3, or 4 or 5.

[0700] After this the column is green meaning that it may be illuminated by the backlight, e.g. the liquid crystals have been oriented, and the LCD pixels have substantially reached their target values.

[0701] When a column is illuminated by a backlight it is shown in yellow. This means that the pixels are visible, e.g. the backlight illuminates the column and the liquid crystal cells in the column modulates the backlight so that an image pattern is displayed.

[0702] 31 columns are illustrated numbered from 1 to 31. This covers part of two logical modules of the LCD panel which is evident from the fact that when looking at the first time step (the top row) there are four columns marked with yellow - two neighbouring columns in each module. Each logical module of the LCD panel has 24 columns. The resolution of the light emitters in the backlight may be half of the resolution of the LCD panel resolution. Thus, the light emitter pitch may be twice the pitch of the pixels of the LCD panel, or even three times the pitch of the pixels / columns of the LCD panel. Each state of the 31 columns are shown during a full multiplexing cycle as a function of time in the multiplexing cycle starting with the state of the 31 columns at time 0.0 in the first row then followed by the state of the 31 columns at time 0.35 mS on the next row.

[0703] The scanning sequence is from left to right one column at a time. This is evident from the fact that the column coloured blue moves one step to the right at each time step. However, another scan sequence can be contemplated, for example from right to left. The important thing in order to have a good image quality of the display is that a band of columns is ready at the same time such that a band can be illuminated and not just a single column of pixels of the LCD panel.

[0704] In the multiplexing cycle some of the columns are updated with values even though the backlight never directs light at those columns.

[0705] Scanning of an LCD column may help ensure DC balance over the LCD panel, but it may also be updated to black instead of the value indicated in the table. If a TN type of LCD panel is selected, updating columns to black before updating them to a next value may have the advantage of eliminating crosstalk between left and right eye images caused by pixels not having completely transitioned to their target values before being illuminated. TN type of panels can have very short transition times to black pixel levels, hence updating them to black may be an effective way to clear any “memory” of past values. Especially if the panel is operating at low temperatures.

[0706] % band

[0707] The backlight illuminates a band of columns of the LCD panel. This is why two neighbouring columns are yellow at the same time.

[0708] With band is meant neighbouring columns of the LCD panel. In the example the band comprises two columns, but another number than two may be contemplated for example more than one such as three or four or five. In the figure it is illustrated that four columns are ready at the same time. This is to be able to illuminate all four columns if needed. For example, if the observer moves to another observation angle that is not covered by the two columns that are illuminated.

[0709] The columns in a band may be updated with the same pixel values such that the columns all show the same column of an image. In other words, there may be a distance from an open aperture slit to the LCD panel and hence if the observer moves to another observation angle, the optical path from an open aperture slit to an eye of the observer may pass through another set of pixel columns of the LCD panel.

[0710] This also means that all columns in a band needs to be ready before the backlight can direct light towards the band. This is reflected in the figure. For example, at time 7.96 the last columns of the left eye image are being generated, e.g. columns 3, 4, 27 and 28 are illuminated by the backlight so that these columns are visible to the left eyes of the observers. The whole left eye image has then been generated, e.g. a first image during a first part of the multiplexing cycle. The right eye image is then to be generated.

[0711] The right eye image is generated as follows. To begin with this has already been prepared at time 4.84 where column 16 is scanned so that the right eye image pixel values are written into the drivers of column 16. And at time 5.19 column 17 is scanned so that the right eye image pixel values that were just scanned into column 16 are also written into the drivers of column 17. And in the following time steps the liquid crystals in the two columns orient themselves to the applied voltage. Columns 16 and 17 are both ready to be illuminated at time 7.96, and at time 8.30 are they illuminated by the backlight.

[0712] % updating in advance

[0713] Thus, during a first part of the multiplexing cycle a first image is generated by the LCD panel and the LCD panel is illuminated by the backlight one LCD column or one band at a time thereby generating one image column at a time during the first part of the multiplexing cycle. During the first part of the multiplexing cycle LCD columns that already has been illuminated and therefore already have generated part of the first image are scanned by the controller such that pixel values for the second image that is to be generated after the first image in the multiplexing cycle are written into the pixel drivers of these LCD columns. This gives these liquid crystals time for orienting such that they are oriented and ready to be illuminated during the second part of the multiplexing cycle where the second image is to be generated and displayed to the observers.

[0714] % distance between bands Since a band is illuminated it is advantageously that there is a distance between the band generating the last part of the first image generated in the multiplexing cycle (the left eye image in the example) and the band generating the first part of the second image generated in the multiplexing cycle.

[0715] This way it may be avoided that pixels generating the first part of the second image which have just been updated and therefore are still in transition are illuminated by light emitted through an open light modulator illuminating the last part of the first image, hence avoiding distracting artifacts of crosstalk between images.

[0716] As an alternative, only one column of the LCD panel should be illuminated at a time. This would remove the above mentioned restraint from the timing, e.g. when the multiplexing cycle transitions from the generation of the first image to the second image the LCD column generating the first part of the second image will be at the opposite side of the LCD panel. However, such an operation does not allow the backlight be constructed from a number of modules performing individual sequential scans. Essentially it may require the backlight to be constructed as one large module.

[0717] The distance may be measured in columns of the LCD. In the example, columns 3 and 4 generate the last column of the left eye image and columns 16 and 17 generate the first column of the right eye image. Between the two bands are 11 columns of the LCD panel, e.g. the distance corresponds to the width of 11 liquid crystal cells. But this could be any number in the range greater than 2 and up to the number of columns in a logical module of the LCD panel, such as 2 - 60, or 2 - 40, or 2 - 30, or 2 to 20, or 4 - 60, or 4 - 40, or 4 - 30, or 4 to 20.

[0718] % Fig. 12c: update scheme of FLCDs

[0719] Fig. 12c shows three logical modules of double light modulators (a double light modulator is two light modulator layers arranged with one in front of the other), and how each module is controlled during half a multiplexing cycle (for a backlight use case), e.g. the states of the light modulators layers at each step of a multiplexing cycle - a full multiplexing cycle comprises the steps needed for generating the left eye image and the right eye image - indicated with left and right next to the graph. A single logical module of double light modulators has previously been shown in fig. 9c in connection with DC balancing of the light modulators. Black shows when one light modulator is closed and there is also a closed light modulator in front of that (two light modulators that are aligned are both closed). Grey is when one light modulator is closed and the light modulator in front or behind it is open (two light modulators that are aligned and one is closed and one is open). White is when one light modulator is open and there is also an open light modulator in front of that (two light modulators that are aligned are both open). In other words, each horizontal line in fig. 12c shows the state of light modulators at a step in a multiplexing cycle where a thin black line segment indicates that one of the two adjacent apertures are open, a thick black line segment indicates that both aperture slits are closed and white indicates that both aperture slits are open. The vertical axis is time going from top to bottom.

[0720] All of the above was also illustrated in fig. 9c as mentioned. However, in fig. 12c it can be seen that there is a distance between where light is transmitted through the light modulator in the last state of the light modulators during the first part of the multiplexing cycle where the first image is generated (left eye image in the example) and where light is transmitted through the light modulator in the first state of the light modulators during the second part of the multiplexing cycle where the second image (right eye image in the example) is generated. This distance corresponds to the distance illustrated in fig. 12b for the same reasons as explained for fig. 12b, e.g. that the LCD panel is updated in bands.

[0721] Thus, the controller may be arranged for controlling the light modulators (whether a single or a double layer) such that a first light modulator being in a light transmitting state at the last step in a first part of the multiplexing cycle where a first image is generated by the LCD panel, and a second light modulator being in a light transmitting state at the first step in a second part of the multiplexing cycle where a second image is generated by the LCD panel, and wherein there is a distance being equal to the width of at least two light modulators between the first light modulator and the second light modulator.

[0722] % DC balance for LCD panel

[0723] Not only the light modulators (FLCDs) needs to maintain a DC balance over time (unless another type of light modulator is used than an FLCD that does not need DC balance), but also the liquid crystals in the LCD panel may need to be DC balanced over time.

[0724] During a multiplexing cycle the LCD panel generates two images, a right eye image and a left eye image. During the multiplexing cycle the polarity of the voltage applied to the liquid crystal cells of the panel will be the same for both images, e.g. during the generation of both the right eye image and the left eye image. In the next multiplexing cycle the polarity is inversed (for example from + to - or vice versa) such that the polarity of the voltage applied to the liquid crystal cells of the panel will be the same for both images. In other words, instead of inverting polarity for each image being scanned out, the polarity may be inverted for each image pair being scanned out, for every second image being scanned out. Polarity inversion may be performed in different ways for example as alternating line polarity or as checker board polarity inversion. Such methods may reduce flicker caused by polarity inversion.

[0725] % Fig. 13: backlight with vertical light guides

[0726] Fig. 13 shows an example configuration with a light guide plate 16, which constitutes an example of a horizontally delimited light emitter, e.g. an elongated light emitter - having a height much greater than its width (during intended operational use), such as more than 2 times greater or more than 3 times or 4 times greater. Another example would be an elongated OLED. Thus, light is emitted as a column of light - the column preferable extends from top to bottom of the display.

[0727] Thus, a vertically elongated light emitter may be an assembly of a LED and a light guide that distributes the light from the LED vertically such that light is seen as a vertical strip of light. Alternatively it could be an elongated LED as mentioned above.

[0728] This may enable using fewer LEDs and less complex electronics, because only one LED may be needed to illuminate the light guide, e.g. the light guide guides the light from the LED vertically so that a stripe of light is emitted - otherwise a plurality of LEDs in a column would have to be needed (this would be the case when the hybrid scan display functions as a stand alone display).

[0729] Further, a light guide may increase the precision of the light sources emitting light towards the LCD panel 15, for example it may be molded with a higher precision than LED mounting tolerance on the PCB, and it may be able to capture light from LEDs mounted with varying precision into the more precisely located light guides.

[0730] % Fig. 14: close up view of a light guide Fig. 14 shows a perspective view of an example of a light guide plate and a spacer located between the light guide plate and a printed circuit board holding the LEDs in the LED matrix 2.

[0731] The light guide plate couples light in from LEDs (first LED 13) on the printed circuit board and outcouples it substantially as uniform thin vertical stripes of illuminated surface.

[0732] There may be incoupling features in the side facing the LEDs and outcoupling features in the side facing the LCD panel 15, such features being calculated and optimized using for example Zemax OpticStudio from company Ansys. The spacer may have light baffles separating leaking light between light guides.

[0733] At the top and / or at the bottom may be located mirrors, oriented orthogonal to the light guide, to reflect light from the light guide so it is emitted at non horizontal angles, in other words extends the appearance of the light guide at the top and at the bottom. This can save a top and / or bottom bezel.

[0734] At side bezels loudspeakers may be included, to hide the bezels or in other words make good use of this space.

[0735] % Fig. 15: cross section of a light guide

[0736] Fig. 15 shows an example of a configuration of a light guide.

[0737] The light guide is illustrated as being elongated, e.g. having a height greater than width as mentioned above.

[0738] The example has two LEDs that emit light into the light guide and the light experience reflections. The light travel is illustrated as the ray traced lines inside the light guide.

[0739] % Fig. 16: zig zag pattern of LEDs in backlight

[0740] Fig. 16 shows a top view of an example a printed circuit board module holding the LEDs in the LED array 2.

[0741] LEDs may be arranged in a staggered pattern, providing more distance between LEDs for wire routing etc. In the example there are three LEDs per vertical line, e.g. more than one LED per vertical line. In a neighboring line the LEDs is at another vertical position thereby achieving the staggered pattern.

[0742] % Fig. 17: backlight modules assembled together

[0743] Fig. 17 shows a top view of an arrangement of a set of printed circuit board modules, e.g. for a modular construction of the display.

[0744] Each PCB module comprising a PCB with LEDs. The staggered LED pattern allows for a more seamless connection between PCB modules, e.g. any bezel between PCB modules may be avoided or at least reduced compared to a non staggered pattern. It will therefore be less obvious to notice by an observer that the display has been assembled with (physical) modules.

[0745] Printed circuit boards may be held in place by for example being glued onto the light guide plate. The light guide plate may cover the full display, thereby ensuring precision of light emitters. Thus, in such an example the light guide plate has a greater area than a single PCB.

[0746] % Fig. 18: electric circuit for driving the backlight LEDs

[0747] Fig. 18 shows an example schematic of an electrical circuit for controlling the LEDs in the LED array 2.

[0748] LEDs may be grouped into groups of 4 neighboring vertically aligned LEDs and they may be controlled so LEDs in each group operate essentially identical, for example by electrically connecting the 4 LEDs in a group as a series-connected string and connecting the string to a voltage source controlled by the controller 9 (not shown in fig. 18). Connecting LEDs in strings may mitigate the disadvantage of using a voltage source rather than a current source, because variations in characteristics of LEDs are averaged resulting in a more consistent illumination of LEDs vs voltage than if LEDs were coupled directly in series. The advantage of using a voltage source, is that several columns of LEDs may by illuminated simultaneously by simply connecting strings in more than one row to a supply voltage, for example by closing more than one switch in the shown schematic.

[0749] % Fig. 19: woman looking at a display Fig. 19 shows a perspective view of an example configuration, where the Hybrid Scan Display is used as a backlight for a large LCD panel 15 in poster / portrait mode (as opposed to the normal landscape orientation that displays normally have, e.g. more pixels horizontally than vertically) built into a display stand and used for digital signage and advertising. The LCD panel 15 may be a 65 inch panel having an active area with dimensions of approximately width x height = 81 x 144 cm, for example it may be a model QN90B 65 from company Samsung.

[0750] % Fig. 20: backlight solution with lenses

[0751] Fig. 20 shows a top view of the example configuration from fig. 19, where the Hybrid Scan Display is used as a backlight for the LCD panel 15.

[0752] However, the example may also be applied to a landscape mode orientation of the display.

[0753] A lens array 17 comprising cylindrical (or acylindrical) lenses may be located adjacent to the panel 15 for example on the side towards the LED array 2. The lens array 17 may have a plane side and this may be oriented towards the panel 15. The configuration may be optimized for the lens array 17 to be close to the panel 15. Light from the LED array 2 transmitted through the lens array 17 may be unpolarized hence avoiding any unwanted effects from birefringence in the lens array 17.

[0754] The lenses and the light valve columns / liquid crystals of the hybrid scan display may in this configuration be much wider than in above configurations. For example, light valve columns and cylinder lenses may be 25mm wide. The LED array 2 may be located for example 100mm behind the panel 15 and lenses may have a focal length of 100mm, hence they may transmit light received from a small area on the LED array 2 as essentially collimated light at the side facing observing eyes.

[0755] The panel 15 may be operated at a frame rate of for example 120fps alternating between left and right eye perspective images, and it may be oriented so it has pixel update scans going from left to right. The Hybrid Scan Display may scan from left to right, synchronized with the update scans of the panel 15, so pixels in the panel 15 are illuminated when they have had time to respond to an update. For example, an area forming a vertical band on the LCD panel 15 to the right of an active scan line may be illuminated, so pixels are illuminated just before they are updated to a new value. The illuminated vertical band may be substantially equal to an area of a lens in the lens array 17, hence a light valve column 18 adjacent to said lens may be opened when the vertical band is illuminated. In other words the Hybrid Scan Display may be operated as a “rolling backlight” or a “scanning backlight” synchronized with the panel 15. An advantage of this configuration is, that it may be more light efficient than the configurations in fig. 12 and 13 while still minimizing crosstalk between observed left and right eye perspective images.

[0756] A set of don’t-care light valve columns comprising a don’t-care light valve column 19 may be calculated as the set of light valve columns being farthest apart from the light valve column 18 so an equal number of light valve columns are open and closed when the set of don’t-care light valve columns are opened. For example the set may be calculated as the number (n / 2)-1 of light valve columns being farthest apart from the light valve column 18, where n is the total number of light valves. The set don’t-care light valve columns may be open during a time slot where the light valve column 18 is also open, while the rest of light valve columns may be closed. Hence since the set of don’t- care light valve columns are far apart from the light valve column 18 being illuminated by the LED array 2, illuminated LEDs in the LED array will also be far apart from any open light valve column except the light valve column 18, so there will be no or very few error beams reaching observing eyes. An advantage of this configuration is, that during a scan operation there may always be an equal number of light valve columns open and closed, hence DC balance is maintained during the scan period and the duration of the blanking period may be zero. In other words, there may no blanking period needed, and the Hybrid Scan Display can start illuminating a subsequent image being scanned-out on the panel 15 substantially right after the previous image was scanned-out.

[0757] % Fig. 21 : angle preserving light integrator

[0758] Fig. 21 shows a top view of an additional arrangement, an angle preserving light integrator, which may be located between the Hybrid Scan Display (or any other directional display) having it’s surface plane parallel to a surface plane of the Hybrid Scan Display, to reduce the visual appearance of seams between lenses or other non-uniformities of the illumination of the image. A first reflective linear polarizer 20 is located between the display and the angle preserving light integrator. The first reflective polarizer may for example be a 3M™ Image Quality Polarizer (IQP). The first reflective polarizer 20 may have a polarization direction allowing polarized light from the display to be transmitted. A wave retarder plate 22 is located on the side of the first reflective polarizer 20 facing towards an observer. The wave retarder plate 22 may for example be a retarder film or a retarder film stack laminated to the first reflective polarizer. The wave retarder plate 22 may be configured so it rotates the direction of polarized light 45 degrees.

[0759] A second reflective linear polarizer 21 is located at the side of the wave retarder plate 22 facing towards an observer. The second reflective polarizer 21 may likewise be a 3M™ Image Quality Polarizer (IQP) and it may be oriented so it reflects most of the polarized light back towards the retarder 22 and transmits a fraction of the light to the side facing an observer. For example the fraction which is transmitted may be equal to the leakage light of light having an opposite polarization direction than the second reflective polarizer 21 , for example the leakage of a 3M™ Image Quality Polarizer (IQP).

[0760] Light that is reflected back towards and transmitted through the retarder plate 22 may have it polarization direction rotated 45 degrees. Hence, when the light reaches the first reflective polarizer 20 it may have been rotated 90 degrees since it passed through the first reflective polarizer 20 the first time, and hence the light may be substantially reflected back towards the retarder plate 22, transmitted through this and reflected back by the second reflective polarizer 21. Hence a fraction may again be transmitted towards an observer, this time at some distance of the light transmitted at the first encounter with the second reflective polarizer, where the distance depends on the angle of incidence of light towards the angle preserving light integrator and of the distance between the two reflecting polarizers. The angle of transmitted light may be substantially preserved.

[0761] Hence several of such light “bounces” may occur, each time with a fraction of the remaining light transmitted towards an observer, and after a number of bounces the transmitted light may have so little optical effect that it is not or barely visible. Hence for a light beam of a certain width, a smearing of the light beam over a horizontal distance may be observed, while the angular direction of the light is preserved. The width of the smearing will depend on the angle, so that for light having an incident angle of 0 degrees relative to an axis perpendicular to the angle preserving light integrator, may be have a width of 0, while for larger angles the width of the smearing is greater. Seams between lenses may be substantially invisible or very low perceptible when the display is observed from an angle of 0 degrees, while it may be visible when viewed from a large angle. Hence the angle preserving light integrator may smear the visible boundary between two neighboring lenses out when observed from an angle and the boundary may be substantially invisible both when viewed directly from the front and when viewed from an angle.

[0762] The smearing width can be adjusted by adjusting by adjusting the distance between the two polarizers and optimized for a pleasant look. If the smearing is too narrow it may not hide lens seams as well as desired and if it is to big light rays having same angle may emanate at points at too great a distance from each other so they cause crosstalk, e.g. is reaching un intended eye of an observer. Additionally the second reflective polarizer 21 may be adjusted by rotating it relative to the first reflective polarizer 20 resulting in different fractions of light being transmitted at encounters with the second reflective polarizer 21.

[0763] % Fig. 22: aperture mask

[0764] Fig. 22 shows a front view of an example of an aperture mask 23.

[0765] The aperture mask may be located in front or behind of the light modulator 1 of the hybrid scan display. The aperture mask 23 may comprise vertical openings having smaller widths than the light valve columns, hence they may have the advantage of focusing light more precisely towards observing eyes accommodating a larger viewing distance. Further, the aperture mask may be made of a non-reflective material, hence reducing reflections of ambient light from a surface of the Hybrid Scan Display.

[0766] The aperture mask 23 may be located close to the light modulator 1 , for example a distance less than a width of a light valve column in the light modulator 1. The distance between the aperture mask 23 and the light modulator 1 may for example be 0.5mm. The aperture mask may be made lithographically on a film or it may be comprised in the light modulator 1 for example as a metal layer similar to metal layers used for example for a black matrix in an led display. Alternatively, it could be made of metal, for example a black nickel shim.

[0767] % Fig. 23: table for DC offset handling

[0768] Fig. 23 deals with how to handle DC offset / voltage imbalances over time for the LCD panel. Liquid crystals may deteriorate if they experience too large a voltage imbalance over time, e.g. if the voltage applied to the crystals have the same polarity / sign all the time.

[0769] Thus, it is desirable to avoid such imbalance.

[0770] Normally, the polarity could be inverted from frame to frame since two consecutive frames often has images closely related to another - unless in the case where there is a change of scene.

[0771] However, this is not necessarily so with a multi view or 3D display. The present disclosure therefore contemplates a new approach.

[0772] Fig. 23 shows a sequence of images displayed. In this case a left eye image and a right eye image. The sequence starts with a left eye image which is then followed by a right eye image which is then followed by a left eye image, e.g. alternating between a left eye image and a right eye image - starting with a left eye image. At the fifth step in the sequence the order is reversed, e.g. a new sequence may begin now starting with the other image than the image that was started with in the previous sequence. This results in a right eye image being displayed twice in a row.

[0773] So far the example shows that the backlight has been at 100 % brightness, but at the point in time when the sequence changes the backlight brightness is changed / lowered, e.g. when the second right eye image is displayed after another right eye image has just been displayed (no left eye images displayed in between) it is displayed with a reduced brightness (in the example 50 % of the maximum brightness). However, it is contemplated that such reduced brightness may not be necessary, e.g. the two right eye images following each other may be displayed with the backlight having maximum brightness (or at least 80 % of maximum brightness).

[0774] The second right eye image is displayed to both eyes (both active viewing zones). However, for the other active viewing zone (the left eye in the example) the image is displayed with reduced brightness, such as no more than 80 % of maximum brightness (the example shows 50 % brightness).

[0775] The polarity / sign of the voltage applied across the liquid crystals in the LCD panel 15 are different, e.g. it may be positive before the changed in sequence and negative after as illustrated in the example or it may be negative before and positive after. In this way a voltage imbalance may be reduced.

[0776] % Fig. 24: LED+diffuser+lenses+double FLCD+LCD

[0777] Fig. 24 shows a preferred embodiment where the display comprises a double FLCD in the backlight for a LCD panel.

[0778] Starting from the back the display comprises a backplane 2. The backplane comprises a plurality of light emitters. The number of light emitters may be half the number of the horizontal resolution of the display or one third. The light emitters may emit light into vertical light guides or the backplane could comprise a two dimensional array of light emitters with a plurality of light emitters arranged horizontally and a plurality of light emitters arranged vertically.

[0779] In the array example there may be a diffuser 16 in front of the light emitters.

[0780] In front of the diffuser is a collection of a lens array 17, a first light modulator layer 1 and a second light modulator layer 14, and at the very front is a LCD panel 15.

[0781] Calibration

[0782] The display may comprise light sensors for calibrating the display, e.g. during manufacturing, transportation, installation, operation or servicing of a display manufacturing tolerances, mechanical shocks or thermal stress may cause the position of light emitters and light modulators relative to desired viewing zones or to an eye tracking system were not as planned. For example, a light emitter may be horizontally offset from its intended position. This may cause that light is not fully directed to an intended viewing zone, for example only half of an eye pupil receives light from all of the display or a part of the display because the view zone defined by the display is offset due to manufacturing, for example resulting in unintended dark areas in images.

[0783] Thus, there may be a need to calibrate the display.

[0784] This may be done automatically by providing a plurality of light sensors. There may be one light sensor per column of light emitters. As it may be recalled the light emitters may be arranged as a 2D array (=grid of light emitters). The term “column” refers to a number of light emitters arranged vertically. In a light guide implementation there may be one light emitter per column.

[0785] Said in other words, the horizontal pitch of the light emitters and the horizontal pitch of the light sensor are substantially the same, e.g. less than 10 %, or 5 %, or 1 %, different from each other.

[0786] Thus, there is a plurality of light sensors which may be arranged horizontally, e.g. some or all could be at the top of the display, and some or all could be at the bottom of the display. They may not necessarily be on the same row, e.g. they could be distributed in the array of light emitters. In such a case some could be in the middle (between top and bottom of the display) - one or more sensors having a light emitter above and a light emitter below.

[0787] The light sensors may be substantially (vertically) aligned with the light emitters, e.g. considering a vertical line through the center of a light emitter (when the display is upright, e.g. mounted on a table stand or a wall mount) the center of a light sensor is not more than 25 % of a light sensor pitch away from the vertical line. This may be the case for each light sensor, e.g. each light sensor is aligned with a light emitter (and each light emitter that a light sensor is aligned with has its own column number, e.g. is on a column different from the columns that the other light emitters are on).

[0788] Thus, for each light sensor there is a light emitter that has the same column number / hor- izontal coordinates (they are in the same vertical plane that also comprises the normal to the display).

[0789] A light sensor may be a photodiode.

[0790] A light sensor may be sensitive to infrared radiation.

[0791] A light sensor may be selected so it has a low sensitivity to wavelengths of light emitted from the plurality of light emitters, hence the calibration can be performed while the plurality of light emitters are active. Alternative, the light sensors may be controlled (by a controller) for detecting light in time intervals where the light emitters does not emit light. The light sensors may have a low sensitivity to wave lengths longer than a maximum wavelength of a polarizer of the light modulator, i.e. a wavelength below which the polarizer has a good extinction ratio, such as above 80 %, or 90%, extinction.

[0792] Each light sensor may include an optical filter in front of the light sensor.

[0793] For example, light sensors may be configured to be sensitive for wavelengths between 650 and 1000 nm, such as between 850 and 920nm. For example a light sensor may be sensitive / detect wavelengths in the range 920 nm + / - 50 nm or + / - 20 nm, e.g. at least the peak detection may be at 920 nm. Light sensors may be configured to be sensitive to substantially only visible light, for example 650-750 nm, hence there may be no need to consider eye safety relating to illumination sources emitting invisible infrared light. Alternatively, it may be configured to be sensitive only to substantially invisible infrared light as mentioned, hence there may be no need to consider disturbing visual light from illumination sources.

[0794] Additionally, electrical circuits may be connected to light emitters, for detection of modulated light, such that light from other sources (sunlight, room illumination etc.) is suppressed, as is well known from for example tv remote controls.

[0795] During calibration, light (at a wavelength that the light sensors can detect) is emitted from the location / position of a feature on an object such as an eye of an observer. This may be done either by placing a light emitter at the feature or emitting light onto the feature and this light is then reflected by the object.

[0796] In the latter case the display may use the observer tracking system of the display to determine the position of the feature. This information is then used for directing light towards the feature for example by means of a light emitter / projector, which may be moved such that it faces the feature. For example, the light emitter / projector may be turned right or left depending on the position of the feature that the tracking system and controller has determined.

[0797] A spot / area next to the feature may be illuminated such that light is reflected from that spot (instead from the eye which could be disturbing). The light emitter / projector may be directional, e.g. having a main beam / lope. The light may be modulated for better detection by light sensors as described above.

[0798] Instead of using an eye of an observer as reference a fixed point in front of the display may be used, and light may be emitted towards the display from the fix point. The fix point may be recognizable by the tracking system, e.g. have a shape that the tracking system and controller is programmed to identify / determine, for example the shape of a face. Or it may be a picture of a face.

[0799] One of the light modulators is set in a light transmitting state such that the light that comes from the position of the eye is transmitted through the light modulator. One of the light sensors then detects the light. Since the light sensors are aligned with the light emitters it is now know which light emitter (column) may be used to emit light towards the eye.

[0800] To summarize, the calibration procedure is:

[0801] 1) emit light from the position of an eye of the observer,

[0802] 2) open a light modulator,

[0803] 3) detect the light transmitted through the open light modulator.

[0804] This procedure may be done for a plurality of eye positions.

[0805] An alternative way of calibration is to operate one display module at a time and recording with a tracking system such as a camera, preferably a high speed camera, a feature of an object such as a face of an observer during a multiplexing cycle.

[0806] For each time slot / step in the multiplexing cycle a controller connected to the tracking system may determine the area of the object which is illuminated (by the first plurality of light emitters). It may then be determined if the illuminated area comprises a specific feature such as an eye and if the area is centered around the specific feature, e.g. if the feature in a horizontal direction is within a minimum distance from edges of a light beam.

[0807] The light emitter column that emits light and the light modulator that is open such that light from the light emitter column is centered is then the correct ones to use for that position of the specific feature / eye, e.g. a pair of light emitter and light modulator for directing light to a specific active viewing zones.

[0808] This information may be entered into a table such as calibration lookup table which can be looked up during operation of the display so that the controller knows which light emitter to scan and which light modulator to scan for a given position of an active viewing zone, e.g. the table comprises the pairs of light emitter and light modulator together with an active viewing zone for each pair.

[0809] Instead of a table a function may be defined for mapping an active viewing zone to a pair of light emitter and light modulator.

[0810] Light sensors are not needed for such a solution.

[0811] % Infrared light emitters for calibration

[0812] The display may comprise dedicated light emitters for illuminating an object, e.g. a second plurality of light emitters, which may be aligned with the first plurality of light emitters in the same way as described above for the light sensors.

[0813] These light emitters may emit light in a light spectrum having another peak wavelength than the first plurality of light emitters, such as infrared light emitters, (the first plurality of light emitters emitting visible light).

[0814] The light emitted by the second plurality of light emitters may be modulated, e.g. a pulsed signal may drive the second plurality of light emitters.

[0815] A tracking system sensitive to the wavelength range of the second plurality of light modulators may track the light pattern emitted by the second plurality of light emitters on an object in front of the display such as a face of an observer, e.g. a camera may record images reflected from the object and together with a controller determine an illuminated area on the object.

[0816] Hereby can the lookup table or function be determined as mentioned above.

[0817] Control of the display in a multiview use % Input

[0818] The hybrid scan display / multiview display may comprise an input or be part of a system comprising an input (not shown in the drawings) for inputting which observer is controlling the display, e.g. so an image with control icons is displayed to the correct ob- server / active viewing zone. Each control icon may activate a function.

[0819] The input may be a control icon in an image, e.g. showing an area of the display where the observer / user may touch the display (when the display has touch functionality). When the control icon is touched the system knows which observer wishes to control the display, e.g. the function of the control icon is to flag which observer is now to be a controlling observer such that the display knows who touches the display. This is important, because the display displays a multitude of images to different observers and each image may have different icons with different functions so the display needs to know what the observer is looking at so it knows which icon is being touch and which function is then to be activated.

[0820] An example may be a car situation with a chauffeur and a passenger. The chauffeur may observe a navigation screen and the passenger may observe a movie. In this case the image for the chauffeur may have control icons for controlling the navigation setting, and the image for the passenger may have control icons for controlling the media player, e.g. the display may display a first image for a first active viewing zone and a second image for a second active viewing zone, the first image comprising a first control icon for controlling the display by the first observer and the second image comprising a second control icon for controlling the display by the second observer.

[0821] Both images may also comprise the same control icons, such as control icons for climate control. In such a case the first control icon and the second control icon result in the same function being activated.

[0822] The input may also be a microphone such that an observer may tell the display that he / she is now to control the display, e.g. an observer may register with the display who it is that is to control the display. The display may then know that a pressure on the screen comes from a certain observer observing a certain image with a control icon in the position of the pressure / contact (from the finger of the observer). The input may also be a physical button - one button for the first observer and another button for the second observer so that when that is switched the display will know if the first or second observer would like to have control.

[0823] Or the input may be an icon in the images for the two observers so that when an icon in an image is pressed the display will know if the first or second observer would like to have control, because each observer only sees his / hers own icon (because the observers are observing different images). All the images may also have an icon for each observer so that each observer can see all icons - including the icons for the other observers.

[0824] The input can also be a tracker system, such as camera or proximity sensor, for detecting or tracking which observer is observing the display. If it is detected that the observer for the first active viewing zone is observing the display any touch on the display will be associated with the control icons in the image for the first active viewing zone. And vice versa if it is detected that the observer for the second active viewing zone is observing the display any touch on the display will be associated with the control icons in the image for the second active viewing zone. It might be that the image for the second active viewing zone also has a control icon at the same area of the display, but the instruction connected to that control icon will not be activated.

[0825] The tracker system may also be used to determine from which direction a hand approaches the display or which hand is touching the display and use that to determine which observer is in the process of touching the display and then know which control icons are relevant, e.g. the controller needs to know if it is a control icon in the image for the first or second active viewing zone that is touched. If it is the observer for the first active viewing zone that is approaching or observing the display it is a control icon for the first image that is touched. And vice versa if it is the observer for the second active viewing zone that is approaching or observing the display it is a control icon for the second image that is touched.

[0826] % essential control icon

[0827] The display may display an image comprising control icons and essential control icons, e.g. controls that activate an essential function for which there is government regulation as to how it is to be controlled. This could be activation of lights or window vipers. Such essential controls may be arranged to be controlled independently of the tracker system or the input. Thus, any touch of an essential control icon will activate the function of the essential control icon.

[0828] % Fig. 25: display in a vehicle

[0829] Fig. 25 illustrates an example of a multiview display installed in a car.

[0830] The display displays an image comprising a control icon 30 and an essential control icon 32.

[0831] % changing viewing zone

[0832] The controller may be arranged to control the display such that there will be an (active) viewing zone at the center of the display, e.g. a viewing zone covering the angles + / - 25 or + / - 20 or + / - 15 or + / - 10 or + / - 5 degrees with respect to the normal of the display which will display the same image as the first viewing zone when the observer in the first viewing zone approaches the display. For example, there may be a third viewing zone arranged between the first viewing zone and the second viewing zone. The image in this viewing zone will be the same as the one in the first viewing zone when the first observer leans / moves towards the display. And the image in that viewing zone will be the same as the one in the second viewing zone when the second observer leans / moves towards the display. The first viewing zone may be to the right (at a right hand side) of the display and the second viewing zone may be at a left hand side of the display. Alternatively, the first viewing zone may be at a left hand side of the display and the second viewing zone may be at a right hand side of the display.

[0833] The tracker system may be used to determine if the observer in one of the viewing zones approaches the display.

[0834] Alternative, when the observer in the first viewing zone approaches the display the same image may be displayed in the first viewing zone and the second viewing zone. Or vice versa, when the observer in the second viewing zone approaches the display the same image may be displayed in the first viewing zone and the second viewing zone.

[0835] Approaching means that the nose of an observer comes closer to the center of the display, for example the observer moves his / her head in a plane parallel to the display or along a line directly towards the display. The normal vector, often simply called the "normal," to a surface is a vector which is perpendicular to the surface at a given point.

[0836] Temperature dependent operation

[0837] Below a certain temperature threshold, such as 15 degrees Celsius or 10 or 5 or 0 degrees Celsius, it is contemplated that the display may switch to 2D operation, e.g. the controller receives input from a temperature sensor in order to control the display.

[0838] Below the temperature threshold the liquid crystal cells could all be open - they are all in the light transmitting state and all the LEDs may generate an image visible through the liquid crystals, e.g. such that there is no modulation by the liquid crystals.

[0839] To avoid DC imbalance / offset in the crystals they may all be closed in the same amount of time as they were open, e.g. they alternate between being open and closed substantially simultaneously (within a time window). And when they are open an image is generated and this image is visible as a 2D image in all viewing zones (because there is no modulation by the crystals).

[0840] In the case that the hybrid scan display operates as a backlight for a LCD panel, it is contemplated that below the temperature threshold a non-directional backlight is generated, e.g. in the same way as above, the crystals are all open and do not provide any modulation below the temperature threshold. When this is the case, the image generated by the LCD panel will be observed as a 2D image in all viewing zones.

[0841] Further, below a certain temperature threshold, a heating operation of the light modulator may be initiated. Such heating operation may comprise heating an ITO layer or other conducting layer in the light modulator, for example by inducing a (de) current through the layer for example by applying a voltage difference to opposing ends of the layer or by applying an AC voltage across liquid crystal cells in the light modulator, said AC voltage preferably having a frequency being high relative to an RC component of opposing cell electrodes, hence inducing a high current.

[0842] A temperature sensor may be provided with the display to measure the temperature of the environment, such as the air temperature, or some other temperature of a component of the display. As for the situation where too many observers are observing the display, the driving signal for the light modulators may comprise a high frequency, such as 5 or 10 or 20 or 30 or 40 kHz, such that the light modulators enters into a semi-transparent state. This will allow for a (2D) image to be transmitted through the light modulators. This can be used in cold conditions, e.g. below a temperature threshold as the one mentioned above.

[0843] Contents DESCRIPTION . 1

[0844] % viewing zone . 1

[0845] Comparison to parallax barrier displays . 2

[0846] Multiplexed parallax barrier display . 3

[0847] Summary of US20050219693. 4 Summary of the disclosed display . 6

[0848] “LED” panel configuration . 9

[0849] “FLCD panel” configuration . 9

[0850] Spacers . 10

[0851] Modules . 10 Fast response times . 11

[0852] Low number of open liquid crystal cells . 11

[0853] Moving aperture . 11

[0854] Pulsed LEDs . 12

[0855] Example of time intervals . 13 Multiplexing cycle . 14

[0856] Interleaved sequence . 15

[0857] Single image part . 16

[0858] Number of modules . 16

[0859] Multiplexing ratio . 17 Sub-sequences . 17 Avoiding “jumping” liquid crystal cells . 18

[0860] Pause between scans of the same LED column . 18

[0861] Frequency . 21

[0862] Fully illuminated aperture . 21

[0863] Liquid crystal cells define the position of pixels in the horizontal plane . 22

[0864] Set of columns . 23

[0865] Diffuser . 23

[0866] Auto-stereoscopic display . 24

[0867] A first aspect of the present disclosure is: . 24

[0868] A second aspect of the present disclosure is: . 24

[0869] A third aspect of the present disclosure is: . 25

[0870] A fourth aspect of the present disclosure is: . 25

[0871] A fifth aspect of the present disclosure is: . 26

[0872] A sixth aspect of the present disclosure is: . 27

[0873] A seventh aspect of the present disclosure is: . 27

[0874] A eight aspect of the present disclosure is: . 28

[0875] A ninth aspect of the present disclosure is: . 28

[0876] % Definition of a function . 31

[0877] % Fig. 1 : display system with two observers . 40

[0878] % Fig. 2: spatial light modulator with one light valve open . 40

[0879] % Fig. 3a: view of LED array . 41

[0880] % Fig. 3B . 45

[0881] % Blanking interval / period . 45

[0882] % Superposition . 45

[0883] % figs. 3C and 3D . 51

[0884] % Fig. 4A: a first step in the multiplexing cycle . 52

[0885] % Fig. 4B: a second step in a multiplexing cycle . 53

[0886] % Fig. 4C: a third step in a multiplexing cycle . 53

[0887] % Fig. 4D: a fourth step in a multiplexing cycle . 54 % Only selected LED columns flash light . 54

[0888] % set of LED columns . 54

[0889] % Fig. 4E: No diffuser . 55

[0890] % resolution = number of light emitters arranged horizontally . 56

[0891] % Wide aperture . 57

[0892] % Neighboring LED columns flashing different light patterns . 58

[0893] % Pitch of aperture . 59

[0894] % Safe opening . 60

[0895] % Flag . 62

[0896] % Fig. 4F . 62

[0897] % fig. 4G . 62

[0898] % Fig. 4H . 65

[0899] %Figs. 4I to K . 65

[0900] % Double FLCD . 67

[0901] % Summary . 67

[0902] % Fig. 4L to 4N: sliding window . 68

[0903] % Inactive viewing zone DC balance for sliding window . 70

[0904] % sliding window with blanking period . 73

[0905] % Polarizers for sliding window . 74

[0906] % Fig. 5: three neighboring LEDs emitting light + diffuser . 76

[0907] % Fig. 6: diffuser far from LEDs . 77

[0908] % don’t care DC balance . 77

[0909] % Fig. 7: a display with modules . 79

[0910] % Fig. 8: active matrix display . 82

[0911] % Figs. 9a and 9b: double FLCD . 83

[0912] % Fig 9c: DC balance for double FLCD . 84

[0913] % Transient voltage . 87

[0914] % Fig. 10a - c: view crash . 88

[0915] % Figs. 11a - c: modular display with two layers of FLCD . 90 % Fig. 12a: backlight solution . 91

[0916] % Fig. 12b: update scheme of LCD panel . 96

[0917] % band . 98

[0918] % updating in advance . 99 % distance between bands . 99

[0919] % Fig. 12c: update scheme of FLCDs . 100

[0920] % DC balance for LCD panel . 101

[0921] % Fig. 13: backlight with vertical light guides . 102

[0922] % Fig. 14: close up view of a light guide . 102 % Fig. 15: cross section of a light guide . 103

[0923] % Fig. 16: zig zag pattern of LEDs in backlight . 103

[0924] % Fig. 17: backlight modules assembled together . 104

[0925] % Fig. 18: electric circuit for driving the backlight LEDs . 104

[0926] % Fig. 19: woman looking at a display . 104 % Fig. 20: backlight solution with lenses . 105

[0927] % Fig. 21 : angle preserving light integrator . 106

[0928] % Fig. 22: aperture mask . 108

[0929] % Fig. 23: table for DC offset handling . 108

[0930] % Fig. 24: LED+diffuser+lenses+double FLCD+LCD . 110 Calibration . 110

[0931] % Infrared light emitters for calibration . 114

[0932] Control of the display in a multiview use . 114

[0933] % Input . 115

[0934] % essential control icon . 116 % Fig. 25: display in a vehicle . 117

[0935] % changing viewing zone . 117

[0936] Temperature dependent operation . 118

[0937] % ITEMS . 124

[0938] % hybrid scan introduction . 124 % binary operation . 125

[0939] % Calibration . 125

[0940] % Chiral smectic crystals . 126

[0941] % sliding window . 126 % sliding window + backlight . 127

[0942] % DC offset with don’t care light valve . 128

[0943] % DC offset with inactive viewing zone . 128

[0944] % hybrid scan with modules . 130

[0945] % Backlight . 131 % band of LCD columns illuminated . 131

[0946] % distance between bands . 131

[0947] % updating in advance for backlight embodiment . 132

[0948] % backlight claim directed to the synchronization . 132

[0949] % DC offset . 133 % DC offset in an alternative formulation . 134

[0950] % view crash . 134

[0951] % number of liquid crystals in a module . 135

[0952] % eye tracking . 135

[0953] % moving aperture . 135 % interleaved . 136

[0954] % LEDs “jump” . 136

[0955] % Aperture “jumps” . 136

[0956] % light being delimited by led . 136

[0957] % pause between flashing a respective LED . 137 % more than one column is updated, but not all columns . 137

[0958] % neighbor columns updated with the same pixel values . 138

[0959] % only visible columns being updated . 138

[0960] % fig. 4E . 138

[0961] % aperture mask . 139 % Lenses . 140

[0962] % double FLCD lag . 140

[0963] % double FLCD DC balance . 141

[0964] % multiview control . 142 % Number of observers and temperature control . 143

[0965] % blanking period . 143

[0966] % changing voltage in blanking period . 144

[0967] % Superposition . 145

[0968] % originale krav . 147 % diffuser . 148

[0969] % miscellaneous . 148

[0970] % don’t care pixels . 149

[0971] % track one krav . 150

[0972] % pause between flashes . 151 % double FLCD . 151

[0973] % view crash . 152

[0974] % modules . 153

[0975] % view crash . 153

[0976] % view crash sliding window . 154 % double FLCD . 155

[0977] % ITEMS The following description is a summary of the features of the present disclosure arranged according to subject.

[0978] % hybrid scan introduction

[0979] 1. A display comprising: - a plurality of light emitters for emitting light,

[0980] - a plurality of light modulators, such as liquid crystal cells. 2. The display according to any of the preceding items, said light emitters arranged in columns with preferably more than one light emitter in each column.

[0981] 3. The display according to any of the preceding items, comprising a controller arranged for controlling said light emitters and said light modulators during a multiplexing cycle for displaying a plurality of images including a first image to a first viewing zone such as a first eye of an observer and a second image to a second viewing zone such as a second eye of said observer.

[0982] % binary operation

[0983] 4. The display according to any of the preceding items, each liquid crystal cell defining an aperture in said light transmitting state.

[0984] 5. The display according to any of the preceding items, each light modulator switching between two states including a light transmitting state for transmitting light from said plurality of light emitters or a light shielding state for shielding light from said plurality of light emitters.

[0985] 6. The display according to any of the preceding items, said liquid crystal cells arranged for operating in binary mode.

[0986] 7. The display according to any of the preceding items, each liquid crystal cell arranged for being operated in binary mode such that each liquid crystal cell exclusively switching between said light transmitting state and said light shielding state.

[0987] % Calibration

[0988] 8. The display according to any of the preceding items, comprising a plurality of light sensors.

[0989] 9. The display according to any of the preceding items, each light sensor aligned with a light emitter.

[0990] 10. The display according to any of the preceding items, said plurality of light sensors having a first horizontal pitch, and said plurality of light emitters having a second horizontal pitch, said first horizontal pitch being less than 10 % different from said second horizontal pitch.

[0991] 11. The display according to any of the preceding items, each of said columns comprising a light sensor.

[0992] % Chiral smectic crystals

[0993] 12. The display according to any of the preceding items, said plurality of light modulators comprising chiral smectic liquid crystals.

[0994] 13. The display according to any of the preceding items, said plurality of light modulators sandwiched between a first transparent sheet and a second transparent sheet with a distance between said first transparent sheet and said second transparent sheet less than 2.2 micrometer, such as less then 2.0 micrometers.

[0995] 14. The display according to any of the preceding items, comprising: spacers between said plurality of light emitters and said plurality of light modulators.

[0996] 15. The display according to any of the preceding items, said plurality of light emitters arranged in a backplane, and said plurality of light modulators arranged in a frontplane.

[0997] 16. The display according to any of the preceding items, comprising: spacers for separating said backplane and said frontplane.

[0998] 17. The display according to any of the preceding items, said spacers arranged in an irregular grid.

[0999] % sliding window

[1000] 18. The display according to any of the preceding items, comprising

[1001] - a controller arranged for controlling said plurality of light emitters such that a first image being generated in a first sequence during a multiplexing cycle, and a second image being generated in a second sequence during said multiplexing cycle, - an observer tracker for tracking the position of one or more observers including a first observer and a second observer in front of said display, said controller arranged for controlling said plurality of light emitters independently from the position of said first observer and said second observer, said controller arranged for controlling said plurality of light modulators as a function of the position of said first observer and the position of said second observer such that a number of light modulators being in a light shielding state for shielding light from said plurality of light emitters from reaching the right eyes of said first observer and said second observer when said first image being generated, and a number of light modulators being in a light shielding state for shielding light from said plurality of light emitters from reaching the left eyes of said first observer and said second observer when said second image being generated.

[1002] % sliding window + backlight

[1003] 19. The display according to any of the preceding items, comprising

[1004] - a LCD panel for generating a first image in a first sequence during a multiplexing cycle, and a second image in a second sequence during said multiplexing cycle, said LCD panel arranged in front of said plurality of light emitters, and said plurality of light modulators arranged between said plurality of light emitters and said LCD panel,

[1005] - an observer tracker for tracking the position of one or more observers including a first observer and a second observer in front of said display,

[1006] - a controller arranged for controlling said plurality of light emitters independently from the position of said first observer and said second observer, said controller arranged for controlling said plurality of light modulators as a function of the position of said first observer and the position of said second observer such that a number of light modulators being in a light shielding state for shielding light from said plurality of light emitters from reaching the right eyes of said first observer and said second observer when said LCD panel generating said first image and a number of light modulators being in a light shielding state for shielding light from said plurality of light emitters from reaching the left eyes of said first observer and said second observer when said LCD panel generating said second image. % DC offset with don’t care light valve

[1007] 20. The display according to any of the preceding items, said plurality of light modulators including a first light modulator, a second light modulator, and a third light modulator, said display comprising:

[1008] - an observer tracker for tracking the position of one or more observers including a first observer in front of said display,

[1009] - a controller arranged for controlling said plurality of light modulators such that said first light modulator being in a light transmitting state for transmitting light to an active viewing zone for displaying a part of an image to an eye of said first observer, said second light modulator being in a light shielding state for preventing cross talk in an inactive viewing zone, and a third light modulator being in a light transmitting state for reducing a DC voltage offset in said third light modulator.

[1010] % DC offset with inactive viewing zone

[1011] 21. The display according to any of the preceding items, comprising:

[1012] - an observer tracker for tracking the position of one or more observers including a first observer and a second observer in front of said display,

[1013] - a controller arranged for determining the position of all right eyes or all left eyes of at least said first observer and said second observer,

[1014] - said controller arranged for controlling said plurality of light modulators and light emitters such that during a first time window said display displaying said first image, and during a second time window said display displaying said second image,

[1015] - said controller arranged for controlling said plurality of light modulators such that during said first time window a first number of light modulators being in a light shielding state for shielding light to all left eyes and a second number of light modulators being in a light transmitting state for transmitting light when a column of light emitters emit light for displaying a part of said first image, and during said second time window said first number of light modulators being in a light transmitting state for transmitting light to all left eyes when a column of light emitters emit light for displaying a part of said second image and said second number of light modulators being in a light shielding state.

[1016] 22. The display according to any of the preceding items, comprising:

[1017] - an observer tracker for tracking the position of one or more observers including a first observer and a second observer in front of said display,

[1018] - a controller arranged for determining the position of all right eyes or all left eyes of at least said first observer and said second observer,

[1019] - said controller arranged for controlling said plurality of light modulators and light emitters such that during a first time window said display displaying said first image, and during a second time window said display displaying said second image,

[1020] - said controller arranged for controlling said plurality of light modulators such that during said first time window a first number of light modulators being in a light shielding state for shielding light to all right eyes and a second number of light modulators being in a light transmitting state for transmitting light when a column of light emitters emit light for displaying said first image, and during said second time window said first number of light modulators being in a light transmitting state for transmitting light to all left eyes when a column of light emitters emit light for displaying said second image and said second number of light modulators being in a light shielding state.

[1021] 23. The display according to any of the preceding items, the sum of said first number and said second number being substantially equal to said plurality of light modulators.

[1022] 24. The display according to any of the preceding items, said second time window being subsequent to said first time window. % hybrid scan with modules

[1023] 25. A display comprising: a number of modules including at least one module and preferably a plurality of modules including a first module and a second module, each module having: a plurality of light emitters preferably arranged in columns for emitting light, a plurality of light modulators, such as liquid crystal cells, said plurality of light emitters divided into in a first set of logical modules constituting a set of light emitter modules, and said plurality of light modulators divided into in a second set of logical modules constituting aperture modules, each light modulator switching between two states including a light transmitting state for transmitting light from said plurality of light emitters and a light shielding state for shielding light from said plurality of light emitters.

[1024] With logical modules is meant that manufacturing wise the display may be manufactured with a layer in one piece of light emitters and a layer in one piece of liquid crystals, e.g. a number of smaller physical modules are not manufactured one by one and then assembled to one large display. Instead, the controller controls the light emitters and liquid crystals in modules operating in parallel to each other. In this way the number of columns of light emitters in the light emitter modules may vary depending on the position of active viewing zones, and light emitter modules may share light emitters, e.g. light emitters arranged behind the boundary zone between two aperture modules may be shared between two light emitter modules.

[1025] % LED column of a neighbor “module” visible in active zone at sharp angle

[1026] 26. The display according to any of the preceding items, said controller arranged for scanning said liquid crystal cells in each aperture module in a sequence such that each liquid crystal cell having been open once creating an effect of a moving aperture through each aperture module during a multiplexing cycle such that a first aperture module having a first moving aperture and a second aperture module having a second moving aperture, when said first active viewing zone having an angle greater than 10 degrees with respect to the normal of said display said controller arranged for scanning a respective column of light emitters behind said first aperture module such that light emitted by said respective column of light emitters being visible at said active viewing zone through said second moving aperture.

[1027] % Backlight

[1028] 27. The display according to any of the preceding items, comprising a LCD panel for generating an image, said LCD panel arranged in front of said plurality of light emitters, said plurality of light modulators arranged between said plurality of light emitters and said LCD panel.

[1029] 28. The display according to any of the preceding items, said plurality of light emitters comprising vertically elongated light emitters.

[1030] 29. The display according to any of the preceding items, said LCD panel alternating between generating an image for a first active viewing zone and a second active viewing zone.

[1031] % band of LCD columns illuminated

[1032] 30. The display according to any of the preceding items, said LCD panel comprising a plurality of columns of liquid crystal cells.

[1033] 31. The display according to any of the preceding items, comprising: a controller arranged for controlling said plurality of columns of liquid crystal cells such that at a step in a multiplexing cycle at least two neighboring columns being updated with the same pixel values such that each of said at least two neighboring columns generating the same column of an image.

[1034] % distance between bands

[1035] 32. The display according to any of the preceding items, comprising: a controller arranged for controlling said plurality of columns of liquid crystal cells such that a first and a second column of said plurality of columns of liquid crystal cells generating a last image column of a first image generated in said multiplexing cycle, and a third and fourth column of said plurality of columns of liquid crystal cells generating a first image column of a second image generated in said multiplexing cycle, said LCD panel comprising at least two columns of liquid crystal cells between said first column and said third column.

[1036] 33. The display according to any of the preceding items, said first and second column being neighbors.

[1037] 34. The display according to any of the preceding items, said third and fourth column being neighbors.

[1038] % updating in advance for backlight embodiment

[1039] 35. The display according to any of the preceding items, comprising: a controller arranged for controlling said plurality of columns of liquid crystal cells such that a first image being generated during a first part of a multiplexing cycle, and during said first part of said multiplexing cycle a first column of liquid crystal cells being illuminated with light from said plurality of light emitters such that a part of said first image being visible by an observer, and while said first image being generated during said first part of said multiplexing cycle said controller arranged for scanning a second column of liquid crystal cells for updating pixel drivers of said second column of liquid crystal cells with pixel values of a second image.

[1040] % backlight claim directed to the synchronization

[1041] 36. The display according to any of the preceding items,

[1042] - said LCD panel arranged for generating a first image for a first active viewing zone and a second image for a second active viewing zone during a multiplexing cycle,

[1043] - said LCD panel including a plurality of light modulators, such as liquid crystals, arranged in columns and updated with image pixel values a number of columns at a time, - said display comprising a controller for scanning said plurality of liquid crystal cells such that each liquid crystal cell having been open once creating an effect of a moving aperture during said multiplexing cycle, said plurality of light emitters and said liquid crystals scanned such that when a column of light modulators being substantially fully updated with image pixel values of said first image said backlight emitting light towards said column such that the image pattern generated by said column being visible at said first active viewing zone, and when a column of light modulators being substantially fully updated with image pixel values of said second image said backlight emitting light towards said column such that the image pattern generated by said column being visible at said second active viewing zone.

[1044] 37. The display according to any of the preceding items, a column of light modulators being substantially fully updated when having reached at least 80 % of an image pixel value.

[1045] % DC offset

[1046] 38. The display according to any of the preceding items,

[1047] - said display including a controller arranged such that

[1048] - said display displaying a first image for a first active viewing zone while said backlight emitting light at a brightness of at least 80 % of the maximum brightness towards said first active viewing zone,

[1049] - said display displaying a second image for a second active viewing zone while said backlight emitting light at a brightness of at least 80 % of the maximum brightness towards said second active viewing zone,

[1050] - said display displaying a third image for said second active viewing zone while said backlight emitting light at a brightness of at least 80 % of the maximum brightness or alternatively no more than 80 % of the maximum brightness towards said second active viewing zone,

[1051] - said display displaying said third image for said first active viewing zone while said backlight emitting light at a brightness of no more than 80 % of the maximum brightness towards said first active viewing zone.

[1052] 39. The display according to any of the preceding items, - said display displaying a fourth image for said first active viewing zone while said backlight emitting light at a brightness of at least 80 % of the maximum brightness, said fourth image displayed after said third image.

[1053] 40. The display according to any of the preceding items, said LCD panel comprising liquid crystals with a first voltage applied when said first image and said second image being displayed, and a second voltage applied when said third image being displayed, said second voltage preferably having an opposite sign compared to said first voltage.

[1054] % DC offset in an alternative formulation

[1055] 41. The display according to any of the preceding items,

[1056] - said display including a controller arranged such that said display having a sequence alternating between displaying images for a first active viewing zone and a second active viewing zone, a respective image for said second active viewing zone being displayed as the next image after a respective image for said first active viewing zone have been displayed, said controller arranged such that at a point in time said sequence comprising an image being displayed for said first active viewing zone and for said second active viewing zone.

[1057] 42. The display according to any of the preceding items, for one of said two images displayed for said first active viewing zone said backlight having a reduced brightness compared to a brightness of said backlight for the other one of said two images.

[1058] 43. The display according to any of the preceding items, said LCD panel comprising liquid crystals with a first voltage having a first sign applied before said point in time and a second voltage having a second sign applied after said point in time, said first sign preferably being opposite said second sign.

[1059] % view crash

[1060] 44. The display according to any of the preceding items,

[1061] - said number of modules including a first module preferably with a first plurality of light emitters and a second module preferably with a second plurality of light emitters, - said controller arranged for scanning said first module and said second module in parallel during a multiplexing cycle such that said first plurality of light emitters being scanned in a first sequence, and said second plurality of light emitters being scanned in a second sequence different from said first sequence.

[1062] 45. The display according to any of the preceding items, said controller arranged for determining when said first sequence and said second sequence causing a view crash causing a first observer observing part of an image intended for a second observer.

[1063] 46. The display according to any of the preceding items, said second sequence being a function of said first sequence for reducing view crash between active viewing zones.

[1064] 47. The display according to any of the preceding items, said controller arranged for changing said second sequence when a view crash being determined for avoiding or minimizing the occurrence of view crash.

[1065] % number of liquid crystals in a module

[1066] 48. The display according to any of the preceding items, said plurality of liquid crystal cells including a range of 8 to 80, such as 8 to 60 or 20 to 40 liquid crystal cells, for balancing view crash reduction and peak brightness of said display.

[1067] % eye tracking

[1068] 49. The display according to any of the preceding items, comprising an observer tracker for tracking the position of an observer in front of said display.

[1069] % moving aperture

[1070] 50. The display according to any of the preceding items, said controller arranged for scanning said liquid crystal cells in a sequence such that each liquid crystal cell having been open once creating an effect of a moving aperture during a multiplexing cycle. % interleaved

[1071] 51. The display according to any of the preceding items, said controller arranged for dividing each image into a sequence of image parts, each image part constituting a single column of pixels of said image, the plurality of sequences of image parts being interleaved into an interleaved sequence.

[1072] 52. The display according to any of the preceding items, said interleaved sequence defining the multiplexing ratio preferably excluding a blanking period.

[1073] 53. The display according to any of the preceding items, a single image part of an image being displayed per module when a liquid crystal cell being in said light transmitting state, and a respective column preferably emitting a light pattern defined by a respective single image part in each step in said multiplexing cycle.

[1074] % LEDs “jump”

[1075] 54. The display according to any of the preceding items, each liquid crystal cell having been open in a time interval including at least two steps of said multiplexing cycle such that at least two columns having flashed light when a respective liquid crystal cell having been open.

[1076] % Aperture “jumps”

[1077] 55. The display according to any of the preceding items, said first column emitting a light pattern a number of times corresponding to the number of active viewing zones while a number of liquid crystal cells corresponding to the number of active viewing zones being addressed in a sequence such that a light pattern is emitted to each active viewing zone.

[1078] % light being delimited by led

[1079] 56. The display according to any of the preceding items, said display arranged such that said light pattern being delimited by liquid crystal cells adjacent said moving aperture such that only a part of the light rays of said light pattern having a line of sight to said first active viewing zone reaching said first active viewing zone. 57. The display according to any of the preceding items, said light pattern being delimited by liquid crystal cells being neighbors to the respective liquid crystal cell being open at a step in said multiplexing cycle.

[1080] 58. The display according to any of the preceding items, said controller arranged for selecting a set of columns for emitting light during a multiplexing cycle, said set emitting light such that light from a first edge of said set being blocked by a liquid crystal cell and light from the center of said set being transmitted through said liquid crystal cell when said liquid crystal cell being in said light transmitting state.

[1081] 59. The display according to any of the preceding items, said set comprising a second edge opposite said first edge and said set emitting light such that light from said second edge being blocked by said liquid crystal cell.

[1082] % pause between flashing a respective LED

[1083] 60. The display according to any of the preceding items, said light emitters arranged in columns including a first column.

[1084] 61. The display according to any of the preceding items, said liquid crystal cells including a first liquid crystal cell and a second liquid crystal cell.

[1085] 62. The display according to any of the preceding items, said controller arranged for scanning said columns in a second sub-sequence including said first column for emitting light when said second liquid crystal cell being in said light transmitting state, between said first column being scanned in said first sub-sequence and in said second sub-sequence a second number of columns being scanned such that said first column having a pause between emitting light when scanned in said first sub-sequence and in said second sub-sequence.

[1086] % more than one column is updated, but not all columns

[1087] 63. The display according to any of the preceding items, said controller arranged for scanning said columns in a first sub-sequence including said first column, said first sub-sequence defining a first number of pixel value updates to said columns such that a plurality of sets of said columns emitting light when said first liquid crystal cell being in said light transmitting state.

[1088] 64. The display according to any of the preceding items, said first number being greater than one and less than the number of said columns.

[1089] % neighbor columns updated with the same pixel values

[1090] 65. The display according to any of the preceding items, said controller arranged for updating two neighboring columns adjacent each other with pixel values such that each of said two neighboring columns being updated with pixel values of a single column of pixels of said image such that each of said two neighboring columns emitting substantially the same light pattern as the other.

[1091] % only visible columns being updated

[1092] 66. The display according to any of the preceding items, said controller arranged such that when said moving aperture changing to a new position from a previous position said controller switching on a first plurality of columns of light emitters for emitting light to active viewing zones, and switching off a second plurality of columns previously being switched on for said previous position such that said second plurality of columns being off during said moving aperture being at said new position for an increased signal to noise ratio.

[1093] If columns that had been on / emitting light just before the moving aperture moved to a new position were not switched off there would be a higher risk of cross talk and the contrast ratio (signal to noise ratio) would be so low that the picture quality would be very low or at least not at the same level as a standard LCD display anno 2024 for example. There would also be a risk of overheating the light emitters, because they would risk being on too long time at a time.

[1094] % fig. 4E

[1095] 67. The display according to any of the preceding items, comprising a controller arranged for controlling said plurality of light modulators such that a number of neighboring light modulators being in a light transmitting state for defining an aperture at a first position at a step in multiplexing cycle, and said controller arranged for controlling said plurality of light emitters such that a first light emitter at a second position emits a light pattern of a pixel column in an image defined by said second position.

[1096] 68. The display according to any of the preceding items, said first position being different from said second position.

[1097] 69. The display according to any of the preceding items, comprising a controller arranged for scanning said plurality of light modulators such that at a first step in a multiplexing cycle a first set of neighbouring light modulators being in a light transmitting state, and at a second step in the multiplexing cycle a second set of neighbouring light modulators being in a light transmitting state,

[1098] 70. The display according to any of the preceding items, said first set of neighbouring light modulators and said second set of neighbouring light modulators having at least one light modulator in common.

[1099] 71. The display according to any of the preceding items, said first set of neighbouring light modulators including a first light modulator, and said second set of neighbouring light modulators including said first light modulator.

[1100] % aperture mask

[1101] 72. The display according to any of the preceding items, comprising an aperture mask preferably arranged such that each aperture in said aperture mask being more narrow than each liquid crystal cell such that the pixel width of said display being defined by the width of the apertures in said aperture mask, said aperture mask preferably arranged in front or behind said liquid crystal cells. An advantage of such an aperture mask is that light may be focused more precisely at a greater distance without having to increase the number of apertures / liquid crystals that needs to be scanned.

[1102] % Lenses

[1103] 73. The display according to any of the preceding items, comprising

[1104] A lens, such as a cylinder or semi-cylinder or acylindrical lens, adjacent each liquid crystal.

[1105] Such cylinders theoretically focuses light to a one dimensional line compared to a round lens focusing to a point.

[1106] 74. The display according to any of the preceding items, said lens being elongated and having a longitudinal axis parallel with the longitudinal axis of a liquid crystal cell.

[1107] % double FLCD lag

[1108] 75. The display according to any of the preceding items, comprising a second plurality of light modulators such as liquid crystal cells.

[1109] 76. The display according to any of the preceding items, comprising each light modulator switching between two states including a light transmitting state for transmitting light from said plurality of light emitters or a light shielding state for shielding light from said plurality of light emitters.

[1110] 77. The display according to any of the preceding items, said second plurality of light modulators arranged between said plurality of light emitters and said first plurality of liquid crystal cells.

[1111] 78. The display according to any of the preceding items, each liquid crystal cell of said second plurality of liquid crystal cells having a width greater than the width of said first liquid crystal cell, and / or at least two neighboring liquid crystal cells of said second plurality of liquid crystal cells being in said light transmitting state at a point in time during a multiplexing cycle.

[1112] 79. The display according to any of the preceding items, said controller arranged for selecting a set of liquid crystal cells of said second plurality of liquid crystal cells for being in said light transmitting state at a point in time during a multiplexing cycle, said set being selected as a function of said first liquid crystal cell such as the position of said first liquid crystal cell, and said first active viewing zone or the horizontal viewing angle of said display.

[1113] % double FLCD DC balance

[1114] 80. The display according to any of the preceding items, said first plurality of light modulators arranged in a first layer, and said second plurality of light modulators arranged in a second layer.

[1115] 81 . The display according to any of the preceding items, comprising a controller arranged for controlling said first plurality of light modulators including a first light modulator such that said first light modulator being in a light transmitting state at a step in a multiplexing cycle while said first plurality of light modulators comprising a first set of light modulators on each side of said first light modulator being in a light shielding state.

[1116] 82. The display according to any of the preceding items, said controller arranged for controlling said second plurality of light modulators such that said first set of light modulators aligned with light modulators of said second plurality of light modulators being in a light shielding state.

[1117] 83. The display according to any of the preceding items, said controller arranged for controlling said first plurality of light modulators such that said first plurality of light modulators comprising a second set of light modulators at said step, said second set of light modulators being in a light shielding state, and aligned with light modulators of said second plurality of light modulators being in a light transmitting state.

[1118] 84. The display according to any of the preceding items, said controller arranged for applying a greater absolute voltage across a light modulator when said light modulator being in a light transmitting state than when said light modulator being in a light shielding state. % multiview control

[1119] 85. A system comprising a multiview display, such as the display according to any of the preceding items, for displaying a first image in a first viewing zone for a first observer and displaying a second image in a second viewing zone for a second observer, said first viewing zone preferably arranged at a right hand side of said multiview display and said second viewing zone preferably arranged at a left hand side of said multiview display or vice versa, said system comprising: an input for inputting when said first observer or when said second observer is a controlling observer of said multiview display.

[1120] 86. The system according to any of the preceding items, said system comprising: a controller arranged for controlling said multiview display such that said first image comprising a first control icon for said first observer and said second image comprising a second control icon for said second observer, and when inputting said first observer as said controlling observer and said first control icon being touched a first function being activated, and when inputting said second observer as said controlling observer and said second control icon being touched a second function being activated, said first function preferably being different from said first function.

[1121] 87. The system according to any of the preceding items, said system comprising: a controller arranged for controlling said multiview display such that said multiview display displays an image comprising a control icon and an essential control icon, and when touching said essential control icon an essential function being activated independently of said input.

[1122] 88. The system according to any of the preceding items, said system comprising: a controller arranged for controlling said multiview display such that when said first observer approaching said multiview display said controller arranged for controlling sai...

Claims

CLAIMS1. A display for emitting light to a plurality of viewing zones including a first viewing zone and a second viewing zone, said display comprising: a number of modules, each module having: a plurality of light emitters for emitting light, a plurality of light modulators such as liquid crystal cells, each light modulator switching between two states including a light transmitting state for transmitting light from said plurality of light emitters or a light shielding state for shielding light from said plurality of light emitters, said display comprising: a controller arranged for scanning said light modulators in a sequence such that each light modulator having been open once during a multiplexing cycle, said controller arranged for scanning said light emitters and said light modulators during said multiplexing cycle for displaying a plurality of images including a first image to said first viewing zone and a second image to said second viewing zone, said controller arranged for dividing each image into a sequence of image parts, each image part constituting a single column of pixels of said image, the plurality of sequences of image parts being interleaved into an interleaved sequence, a single image part of an image being displayed when a light modulator being in said light transmitting state such that said single image part being visible in said first viewing zone and non-visible in said second viewing zone.

2. The display according to any of the preceding claims, said plurality of light modulators arranged for operating in binary mode.

3. The display according to any of the preceding claims, said number of modules including a first module and a second module, said controller arranged for scanning said first module and said second module in parallel during a multiplexing cycle such thatsaid first plurality of light emitters being scanned in a first sequence and said second plurality of light emitters being scanned in a second sequence different from said first sequence.

4. The display according to any of the preceding claims, said controller arranged for determining when said first sequence and said second sequence causing a view crash causing a first observer observing part of an image intended for a second observer.

5. The display according to any of the preceding claims, said second sequence being a function of said first sequence for reducing view crash between active viewing zones.

6. The display according to any of the preceding claims, said controller arranged for changing said second sequence when a view crash being determined for avoiding or minimizing the occurrence of view crash.

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