Optical system with a collimation film and a light control layer

Abstract

A display system includes a display region configured to form an image thereacross for viewing by a viewer and including a light emitting region configured to emit light and a light non-emitting region not configured to emit light; a light diffractive layer between the eye of the viewer and the display region and disposed substantially parallel to the display system from, the display region, the light diffractive layer having a light diffractive region configured to diffract light and a light non-diffractive region not configured to diffract light, the light diffractive and non-diffractive regions of the light diffractive layer aligned with the respective light non-emitting and emitting regions of the display region; and a light control layer disposed between the light diffractive layer and the eye of the viewer and having an optical transmittance that varies as a function of an incident angle of an incident light.

Description

PA102876W002OPTICAL SYSTEM WITH COLLIMATION AND LIGHT CONTROL LAYERSSummary

[0001] In some aspects of the present description, a display system is provided, the display system including a display region configured to form an image thereacross for viewing by an eye of a viewer, a light diffractive layer configured to be between the eye of the viewer and the display region, and a light control layer disposed between the light diffractive layer and the eye of the viewer. The display region includes a light emitting region configured to emit light and a light non-emitting region not configured to emit light. The light diffractive layer is spaced apart along a thickness direction of the display system from the display region, and has a light diffractive region configured to diffract light and a light non-diffractive region not configured to diffract light. The light diffractive and non- diffractive regions of the light diffractive layer are aligned, and substantially co-extensive in length and width with, the respective light non-emitting and emitting regions of the display region. The light control layer has an optical transmittance that varies as a function of an incident angle of an incident light.

[0002] In some aspects of the present description, an optical system is provided, the optical system including a display configured to emit an image for viewing by an eye of a viewer and having a plurality of spaced-apart light emitting pixels defining one or more non-light emitting regions therebetween; a light control film disposed between the display and the eye of the viewer and having an optical transmittance that varies as a function of an incident angle of an incident light; and a collimation film disposed between the display and the light control film and having one or more periodic structures substantially covering only, and aligned in a one-to-one correspondence with, the one or more non-light emitting regions. Light emitted by the light emitting pixels is diffractively transmitted by the collimation film and exits the display system in air toward a viewer after passing through the light control film. The emitted light has a maximum brightness Imax across a continuous angle range that is at least 20 degrees wide that is less than about 0.5 on a normalized brightness profile for the plurality of light emitting pixels without the collimation film and the light control film. The light control film and the collimation film, in combination, increase an on-axis brightness of the display by at least about 10% when compared to a comparative optical system which is identical except that the comparative optical system does not comprise the collimation film.

[0003] In some aspects of the present description, a display system is provided, the display system including a plurality of light emitting pixels defining a plurality of first inter-pixel regions therebetween, each of the first inter-pixel regions devoid of any light emitting pixels; a light diffractive layer, and a light control layer. The light diffractive layer is disposed on, and spaced apart along a thickness direction of the display system from, the light emitting pixels and includes a plurality of light diffractive regions substantially aligned and coextensive with the plurality of firstinter-pixel regions in one-to-one correspondence. The light diffractive regions include a first plurality of substantially parallel linear diffractive elements extending along a same in-plane first direction and arranged along a same in-plane, orthogonal, second direction. The light control layer is disposed on the light diffractive layer opposite the light emitting pixels and has an optical transmittance that varies as a function of an incident angle of an incident light. Light emitted by the pixels is diffractively transmitted by the light diffractive layer and exits the display system in air toward a viewer after passing through the light control layer, and has a maximum brightness Imax across a continuous angle range that is at least 20 degrees wide and is less than about 0.5 of a normalized brightness profile for the plurality of light emitting pixels without the light diffractive layer and the light control layer. The light control layer and the light diffractive layer, in combination, increase an on-axis brightness of the plurality of light emitting pixels by at least about 10% when compared to an comparative display system which is identical except that the comparative display system does not comprise the light diffractive layer.

[0004] In some aspects of the present description, an optical stack is provided, the optical stack including a light diffractive film having a light diffractive region configured to diffract light and a light non-diffractive region not configured to diffract light, and a light control film disposed on the light diffractive film and having an optical transmittance that varies as a function of an incident angle of an incident light. The location and extent of the light diffractive and light non-diffractive regions of the light diffractive film is configured to correspond to respective light non-emitting and emitting regions of a display.Brief Description of the Drawings

[0005] FIGS. 1 A and IB illustrate the details of a light control film known in the art, including its optical characteristics;

[0006] FIGS. 2A and 2B illustrate the details of a light collimation film known in the art, including its optical characteristics;

[0007] FIGS. 3 A and 3B illustrate the details of an optical system combining collimation and light control layers, in accordance with an embodiment of the present description;

[0008] FIG. 4 is a normalized plot of brightness / optical transmission of an optical system combining collimation and light control layers, in accordance with an embodiment of the present description;

[0009] FIGS. 5 A and 5B provide structural details of an optical system combining collimation and light control layers, in accordance with an embodiment of the present description; and

[0010] FIGS. 6A and 6B provide additional structural details of an optical system combining collimation and light control layers, in accordance with an embodiment of the present description.Detailed Description

[0011] In the following description, reference is made to the accompanying drawings that form a part hereof and in which various embodiments are shown by way of illustration. The drawings are not necessarily to scale. It is to be understood that other embodiments are contemplated and may be made without departing from the scope or spirit of the present description. The following detailed description, therefore, is not to be taken in a limiting sense.

[0012] The present invention relates to display systems, and more particularly to optical systems and methods for enhancing the brightness and viewing characteristics of displays using light control films and collimation technologies.

[0013] Display systems are ubiquitous in modem technology, ranging from consumer electronics such as smartphones and televisions to specialized applications in automotive and industrial settings. A critical aspect of these display systems is their ability to control light to produce clear, bright, and artifact-free images across a range of viewing angles.

[0014] One common approach to managing light in display systems involves the use of light control films (LCFs). These films are designed to control the direction and intensity of light emitted from the display, thereby enhancing the viewing experience in some applications, such as in an automotive display, and restricting it in others, such as a privacy screen. Traditional LCFs, such as microreplicated louvres and conformal coating and release louvres, are effective in reducing glare and improving contrast. However, they often suffer from significant transmission loss, which reduces the overall brightness of the display. Additionally, depending on the design, LCFs can introduce optical artifacts at high viewing angles, such as improper cutoff angles, which degrade the quality of the displayed image.

[0015] Collimation technologies, which can involve the use of periodic structures to direct light, have also been employed to enhance display brightness. These technologies are designed to increase on-axis brightness by directing more light towards the viewer. However, collimation films can introduce off-axis artifacts (e.g., secondary brightness peaks at off-angle viewing), which can detract from the overall viewing experience.

[0016] Given the limitations of current light control and collimation technologies, there is a clear need for an improved optical system that can effectively combine these technologies to enhance display brightness and viewing characteristics without introducing significant optical artifacts. Such a system would ideally maintain high on-axis brightness while providing a smooth and artifact-free viewing experience across a wide range of angles. Additionally, it would address the transmission loss typically associated with LCFs and the off-axis artifacts associated with collimation films.

[0017] According to some aspects of the present description, a display system includes a display region configured to form an image thereacross for viewing by an eye of a viewer, a light diffractivelayer configured to be between the eye of the viewer and the display region, and a light control layer disposed between the light diffractive layer and the eye of the viewer.

[0018] In some embodiments, the display region may include a light emitting region configured to emit light and a light non-emitting region not configured to emit light. In some embodiments, the light diffractive layer may be disposed substantially parallel to, and spaced apart along a thickness direction (e.g., a z-axis) of the display system from, the display region. In some embodiments, the light diffractive layer may include a light diffractive region configured to diffract light and a light non-diffractive region not configured to diffract light. In some such embodiments, the light diffractive and non-diffractive regions of the light diffractive layer may be aligned, and substantially coextensive in length (e.g., an x-axis) and width (e.g., a y-axis), with the respective light non-emitting and emitting regions of the display region.

[0019] In some embodiments, the light control layer may have an optical transmittance that varies as a function of an incident angle of an incident light (e.g., only allows light within a certain range of incident angles). In some embodiments, the light control layer may include a plurality of alternating light transmissive and light absorbing regions (e.g., optically transparent light transmissive regions separated by a plurality of light absorbing louvers). In some embodiments, the light absorbing regions may include a light absorbing material and / or a light absorbing coating.

[0020] In some embodiments, the light diffractive region may include a plurality of substantially parallel linear diffractive elements extending along a same in-plane first direction (e.g., a y-axis) and arranged along a same in-plane orthogonal second direction (e.g., an x-axis). In some such embodiments, the light diffractive region may further include a second plurality of substantially parallel linear diffractive elements extending along the in-plane second direction (e.g., an x-axis) and arranged along the in-plane first direction (e.g., a y-axis).

[0021] In some embodiments, the location and the extent of the light diffractive region may be such that the light diffractive region covers no more than about 20%, or no more than about i0%, or no more than about 5% of the light emitting region (i.e., in such embodiments, the light non- diffractive region may be substantially centered over each light emitting region or pixel in a thickness direction (e.g., a z-direction). However, in other embodiments, the location and extent of the light diffractive region may be selected such that the light diffractive region diffracts light from the light emitting region to directions such that the incident angle of the light incident on the light control layer substantially corresponds to incident angles for which the optical transmittance of the incident light through the light control layer is greater than about 50% (i.e., no matter where the light diffractive regions are in relation to the light emitting region of the display region, the light diffractive region may be disposed such that it directs light into the light control film such that the transmission of light through the light control film is optimized).

[0022] According to some aspects of the present description, an optical system includes a display configured to emit an image for viewing by an eye of a viewer. The display includes a plurality ofspaced-apart light emitting pixels that define one or more non-light emitting regions between them. A light control fdm is positioned between the display and the eye of the viewer, and this film has an optical transmittance that varies based on the incident angle of incoming light. In some embodiments, the light control film may include a plurality of alternating light transmissive and light absorbing regions.

[0023] In some embodiments, a collimation film is placed between the display and the light control film. This collimation film includes one or more periodic structures that are substantially aligned in a one-to-one correspondence with, the non-light emitting regions. The arrangement is such that light emitted by the light emitting pixels is diffractively transmitted by the collimation film and exits the display system in air toward the viewer. After passing through the light control film, this light has a maximum brightness (Imax) across a continuous angle range that is at least 20 degrees wide and which is less than about 0.5 of a normalized brightness profile for the light emitting pixels without the collimation film and the light control film.

[0024] Additionally, the combination of the light control film and the collimation film increases the on-axis brightness of the display by at least about 10%, or at least about 15%, or at least about 20% when compared to a comparative optical system that is identical except for the absence of the collimation film. In some embodiments, no more than about 20%, or no more than about 10%, or no more than about 5% of the periodic structures cover the light emitting pixels.

[0025] In other embodiments, the periodic structures may include a plurality of substantially parallel linear diffractive elements extending along the same in-plane first direction (e.g., a y-axis) and arranged along the same in-plane orthogonal second direction (e.g., an x-axis). In some such embodiments, the periodic structures may further include a second plurality of substantially parallel linear diffractive elements extending along the in-plane second direction (e.g., an x-axis) and arranged along the in-plane first direction (e.g., a y-axis).

[0026] According to some aspects of the present description, a display system includes a plurality of light emitting pixels that define a plurality of first inter-pixel regions between them, where each of the first inter-pixel regions is devoid of any light emitting pixels. In some embodiments, a light diffractive layer may be positioned on and spaced apart along a thickness direction (e.g., a z- axis) of the display system from the light emitting pixels. This light diffractive layer includes a plurality of light diffractive regions that are substantially aligned and coextensive with the plurality of first inter-pixel regions in a one-to-one correspondence. The light diffractive regions may include a first plurality of substantially parallel linear diffractive elements extending along a same in-plane first direction (e.g., a y-axis) and arranged along a same in-plane, orthogonal, second direction (e.g., an x- axis).

[0027] In some embodiments, a light control layer may be positioned on the light diffractive layer opposite the light emitting pixels and may have an optical transmittance that varies as a function of the incident angle of the incident light. In some embodiments, for example, the light control layermay include a plurality of alternating light transmissive and light absorbing regions (e.g., light absorbing louvers). This configuration ensures that light emitted by the pixels, which is diffractively transmitted by the light diffractive layer and exits the display system in air toward a viewer after passing through the light control layer, has a maximum brightness (Imax) across a continuous angle range that is at least 20 degrees wide and which is less than about 0.5 of a normalized brightness profile for the plurality of light emitting pixels without the light diffractive layer and the light control layer.

[0028] Additionally, in some embodiments, the light control layer and the light diffractive layer may, in combination, increase the on-axis brightness of the plurality of light emitting pixels by at least about 10%, or at least about 15%, or at least about 20% when compared to a comparative display system that is identical except that it does not include the light diffractive layer.

[0029] In some embodiments, the light diffractive regions may also include a second plurality of substantially parallel linear diffractive elements extending along the in-plane second direction (e.g., an x-axis) and arranged along the in-plane first direction (e.g., ay-axis).

[0030] According to some aspects of the present description, an optical stack for use in a display system includes a light diffractive film and a light control film. The light diffractive film is designed with a light diffractive region that is configured to diffract light and a light non-diffractive region that is not configured to diffract light. The location and extent of the light diffractive and non-diffractive regions of the light diffractive film are arranged to correspond to the respective light non-emitting and emitting regions of a display.

[0031] In some embodiments, the light control film is positioned on the light diffractive film and has an optical transmittance that varies based on the incident angle of the incoming light. The light control film may include a plurality of alternating light transmissive and light absorbing regions. These regions can be designed to optimize the control of light passing through the film, enhancing the display's performance (including increasing brightness at the desired viewing angles, and / or reducing brightness at undesired or off-axis viewing angles).

[0032] In some embodiments, the light diffractive region of the light diffractive film includes a plurality of substantially parallel linear diffractive elements extending along a first in-plane direction (e.g., a y-axis) and arranged along a second in-plane orthogonal direction (e.g., an x-axis). Additionally, the light diffractive region may include a second set of substantially parallel linear diffractive elements extending along the in-plane second direction (e.g., an x-axis) and arranged along the in-plane first direction (e.g., ay-axis).

[0033] In some embodiments, the location and extent of the light diffractive region are configured such that, when the optical stack is placed on the display, no more than about 20%, or no more than about 10%, or no more than about 5% of the light diffractive region covers the light emitting regions of the display. This configuration ensures that the light diffractive region is optimally positioned to enhance the display's performance by directing light in a manner that maximizes theoptical transmittance through the light control film. In other embodiments, the alignment of the light diffractive region to the light emitting regions may be adjusted as necessary to meet the display’s optical requirements.

[0034] Turning now to the figures, FIGS. 1 A and IB illustrate the details of a light control film known in the art, including its optical characteristics. Some display systems, such as optical system 450 of FIG. 1A, use a light control film 350 to preferentially absorb / filter light emitted from a display 150 at undesirable viewing angles. This type of filter / film may be used to ensure one viewer (such as a driver viewing a heads-up display) at a first viewing angle sees an optimal image, where a second viewer at a second viewing angle (such as a passenger looking at the heads-up display) may not see the emitted image at all (or may not see it optimally).

[0035] For example, light rays 70 are emitted from light emitting pixels 160 (e.g., light-emitting diodes) of display 150. Non-emitting regions 165 (i.e., the spaces between light emitting pixels 160) provided a separation between adjacent light emitting pixels 160. Some light rays 70 are emitted from light emitting pixels 160 such that they are incident on the light control film 350 with an angle of incidence which is substantially parallel to the direction of the light controlling elements within the light control film 350. For example, a light control film 350 may include alternating light transmissive regions 360 (e.g., optically transparent regions which substantially allow transmission of light) and light absorbing regions 365 (e.g., light absorbing louvers). If a light ray (such as light ray 70a) is at a high enough angle of incidence to the light absorbing regions 365 of light control film 350, the light rays 70a are absorbed by the light absorbing region 365 and not allowed to transmit through light control film 350.

[0036] The effect of using a light control film 350, in this embodiment, with a display 150 are that the light transmitted therethrough is substantially on-axis, and light at larger angles of incidence (i.e., off-axis and not orthogonal to the light control film, or at least not in alignment with the angle of the light absorbing regions 365) is absorbed and not transmitted. The effects of this are shown in chart 550 of FIG. IB, which shows a normalized plot of transmission (e.g., brightness) as perceived by a viewer of the display at various viewing angles with and without the light control film 350. The plot has been normalized so that the output of the display 550a without the light control film 350 has a peak transmission / brightness 550b at 100% (which may also be expressed as 1 on a scale of 0 to 1) at a viewing angle of 0 degrees. It should be noted that the definition of “on-axis” depends on the requirements for the particular application and refers to the desired optical axis of the image light, which may not always be relative to an actual axis of the physical optical system.

[0037] Plot 560a shows the result of adding light control film 350 between display 150 and a viewer (not shown). Plot 560a has a much narrower full width at half maximum (the transmission band is narrower) with the light control film 350a, but the peak brightness 560b has dropped relative to the peak brightness 550b of just the display 150 without the light control film 350. Stated anotherway, with a light control film 350, there is a penalty of reduced peak brightness paid for the relative increase in on-axis output (or the reduction in off-axis brightness).

[0038] Another known technique for improving the output characteristics of a display 150 is shown in FIGS. 2A and 2B. Optical system 455 includes a display 150 with light emitting regions / pixels 160 (separated by non-light emitting regions 165) which emit light for viewing by a viewer (not shown). Looking at FIG. 2B, plot line 555a shows the normalized transmission of the display 150 without any films between display 150 and the viewer. This line may be compared to plot 550a in FIG. IB and has a normalized peak brightness 555b at 100 percent and at a 0-degree viewing angle (but also at off-axis viewing angles such as + / - 40 degrees).

[0039] One solution for increasing brightness as perceived by a viewer is the addition of a collimation film 250 between display 150 and the viewer. A collimation film such as collimation film 250 in FIG. 2A typically includes light diffracting regions 265 alternating with light non-diffracting regions 260. Light diffracting regions 265 typically include diffractive features (e.g., parallel linear diffractive elements) which take light 72a which is emitted by display 150 at an angle that is sufficiently off-axis (i.e., not orthogonal to the display and outside of an acceptable emission angle) and diffracts that light to be more on-axis. The result of this collimation is shown in chart 555 of FIG. 2B, where plot 565a showing the light perceived by a viewer after the display image is transmitted by collimation film 250 has a brightness gain at 565b that is over 50% above the normalized brightness 555b on plot 555a for the display 150 output without the collimation film 250.

[0040] Unfortunately, these collimation films 250 can have optical artifacts, such as shown in FIG. 2A and light ray 72b, which is transmitted by an adjacent non-diffracting region 260. This unintended transmission of light 72b through adjacent non-diffracting regions 260 may result in the side lobes 575 shown in FIG. 2B. These side lobes provide secondary brightness peaks at off-axis viewing angles (e.g., at +- 40 to 60 degrees viewing angles, in this example).

[0041] Both light control films and light collimation films such as those illustrated in FIGS. 1 A- 1B and 2A-2B exhibit unwanted optical artifacts and side effects. Light control films, such as louver films, allow the light output to a viewer to be more on-axis (i.e., be confined to smaller “on-axis angular ranges, or have reduced off-axis brightness), but incur a significant penalty in peak brightness due to loss of light through absorption by the light control film. Collimation films bring a significant gain in brightness for on-axis viewers but can create secondary brightness side lobes in the output for off-axis viewers. It has been found that combining both films together, as described herein, has the unexpected benefit of producing an optical gain / improvement over a light control film alone and also eliminating the large side lobes in the transmission when using collimation films alone.

[0042] FIGS. 3 A and 3B illustrate the details of such an optical system combining collimation and light control layers, in accordance with an embodiment of the present description. In some embodiments, such as that of FIG. 3 A, an optical system 400 may include a display 100, a collimation film 200, and a light control film 300. In some embodiments, the collimation film 200 may bedisposed between display 100 and light control film 300, such that the high optical gain of collimation film 200 can be fed into light control film 300 to create the optical transmission output, as shown in FIG. 3B.

[0043] In some embodiments, display 100 may include a display region configured to form an image thereacross for viewing by an eye of a viewer and one or more light emitting regions 110 configured to emit light (e.g., light emitting pixels or diodes) and one or more light non-emitting regions 115 (between light emitting pixels) not configured to emit light. Light rays 74 (including 74a and 74b) are emitted by light emitting regions 110. Light rays 74 then become incident on collimation film 200 (also known as a light diffraction film 200) and are substantially transmitted therethrough. Light rays 74 which are already “on-axis” or substantially orthogonal to collimation film 200 may be substantially transmitted by non-diffractive regions 210 (i.e., those areas without diffraction features) without being diffracted or redirected into another direction. Light rays 74a which are incident on light diffractive regions 215 may be diffracted into a new direction (e.g., may be brought more “on- axis” as seen by a viewer) by light diffractive regions 215. Other light rays 74b, which may be at the widest emission angles (i.e., those light rays farther off of the intended optical axis direction) may also be transmitted by neighboring non-diffractive regions 210 (i.e., they may be transmitted even though they are not at the desired viewing angle). Again, it should be noted that the definition of “on-axis” depends on the requirements for the particular application and refers to the desired optical axis of the image light, which may not always be relative to an actual axis of the physical optical system.

[0044] Substantially all of these light rays 74 / 74a / 74b, as they have or have not been redirected, are then incident on light control film 300. In some embodiments, light rays 74 and 74a, which are incident at the appropriate (on-axis) angles to light control film 300 (i.e., they are substantially parallel to or within the acceptance angle range created by the light absorbing regions 315 of light control film 300), are substantially transmitted therethrough (through light transmitting regions 310) toward the viewer (not shown). Light rays 74b, which are transmitted at unwanted off-axis angles, are incident on light control film 300 and are substantially absorbed by light absorbing regions 315 and are therefore not transmitted therethrough.

[0045] As a result of this combination (and the specific layer order) of collimation film 200 and light control film 300, an output such as that shown in chart 500 of FIG. 3B is created, showing optical transmission (normalized to the display output without the films) versus the viewing angle at which the image is viewed. Again, plot 500a with peak brightness 500b at a 0-degree viewing angle represents the output seen by a viewer (normalized to 100 percent) from just the display output with no intervening films. Plot 510a with peak brightness 510b represents the output seen by the viewer after the light / image rays have passed first through the collimation film 200 and then the light control film 300. Peak brightness 510b shows, in this example, a gain of about 27% over the display peak brightness 500b without the fdms. Also, the width of the 510a output curve (e.g., the full width at halfmaximum brightness) is significantly narrower (between about +20 degrees and -20 degrees) than the original curve 500a, with no side lobes (such as side lobes 575 as shown in FIG. 2A).

[0046] In fact, looking at this same chart 500 in FIG. 4, there exist broad areas 520 where a maximum brightness (Imax) in these areas 520, across a continuous angle range that is at least 20 degrees wide (e.g., areas 520 in FIG. 4 are each about 55 degrees wide) that has is less than about 0.5 (i.e., about 50%) of the normalized brightness profile 500a for the plurality of light emitting pixels without the collimation film and the light control film as shown in FIG. 4.

[0047] FIGS. 5A-5B and 6A-6B provide structural details of an embodiment of an optical system combining collimation and light control layers, according to the present description. FIG. 5 A is a top plan view of one embodiment of a display / display region 100 which includes a plurality of light emitting regions / pixels 110 separated by light non-emitting regions 115. The scale and relative positioning of light emitting regions 110 and light non-emitting regions 115 may not be to scale and is provided for discussion purposes.

[0048] FIG. 5B is a top plan view of one embodiment of a collimation film 200. This embodiment includes light diffracting regions 215 alternating with light non-diffracting regions 2f0. in this embodiment, the light diffractive regions 215 include a plurality of substantially parallel linear diffractive elements extending along a same in-plane first direction (e.g., the y-axis shown in FIG. 5B) and arranged along a same in-plane orthogonal second direction (e.g., the x-axis).

[0049] In the embodiments shown in FIGS. 6A-6B, the collimation (or light diffractive) film 200a include a first plurality of substantially parallel linear diffractive elements extending along a same in-plane first direction (e.g., the y-axis shown in FIG. 6B) and arranged along a same in-plane orthogonal second direction (e.g., the x-axis), as well as a second plurality of substantially parallel linear diffractive elements extending along the in-plane second direction (e.g., the x-axis) and arranged along the in-plane first direction (e.g., the y-axis). That is, in this embodiment, collimation film 200a has linear diffractive elements which are crossed and which extend in different, orthogonal directions, rather than the single direction of collimation film 200 as shown in FIG. 5B.

[0050] FIG. 6A shows optical system 400a which includes a collimation film 200a disposed on top of display region 100. Please note that optical system 400a would also include a light control film which would be disposed over collimation film 200a but which has been omitted in FIGS. 6A and 6B to better show the structural details of how collimation film 200a is aligned with display region 100. In FIG. 6A, collimation film 200a has non-diffracting regions 2f0 which are substantially aligned with light emitting regions 110 and also has diffracting regions 215 which (in this embodiment) substantially cover the light non-emitting regions 115 of display region 100. It should be noted that other alignments of the collimation film 200a and display region 100 are possible within the scope of this description, and this description is not intended to be limiting in any way.

[0051] FIG. 6B is another, closer view of optical system 400a of FIG. 6A, showing additional detail. In this embodiment, diffractive regions 215 alternate with, or define a pattern with, non-diffractive regions 210. In this embodiment, non-diffractive regions 210 (areas without diffractive elements) are substantially aligned in a one-to-one correspondence with light emitting regions / pixels 110. In other embodiments, such as an optical system using collimation film 200 of FIG. 5B with linear diffractive features in only a single direction, may allow more of the non-emitting region 115 of the display region 100 to “show through” the collimation film 200a. Other embodiments are possible within the scope of this description.

[0052] Terms such as “about” will be understood in the context in which they are used and described in the present description by one of ordinary skill in the art. If the use of “about” as applied to quantities expressing feature sizes, amounts, and physical properties is not otherwise clear to one of ordinary skill in the art in the context in which it is used and described in the present description, “about” will be understood to mean within 10 percent of the specified value. A quantity given as about a specified value can be precisely the specified value. For example, if it is not otherwise clear to one of ordinary skill in the art in the context in which it is used and described in the present description, a quantity having a value of about 1 , means that the quantity has a value between 0.9 and 1.1, and that the value could be 1.

[0053] Terms such as “substantially” will be understood in the context in which they are used and described in the present description by one of ordinary skill in the art. If the use of “substantially equal” is not otherwise clear to one of ordinary skill in the art in the context in which it is used and described in the present description, “substantially equal” will mean about equal where about is as described above. If the use of “substantially parallel” is not otherwise clear to one of ordinary skill in the art in the context in which it is used and described in the present description, “substantially parallel” will mean within 30 degrees of parallel. Directions or surfaces described as substantially parallel to one another may, in some embodiments, be within 20 degrees, or within 10 degrees of parallel, or may be parallel or nominally parallel. If the use of “substantially aligned” is not otherwise clear to one of ordinary skill in the art in the context in which it is used and described in the present description, “substantially aligned” will mean aligned to within 20% of a width of the objects being aligned. Objects described as substantially aligned may, in some embodiments, be aligned to within 10% or to within 5% of a width of the objects being aligned.

[0054] All references, patents, and patent applications referenced in the foregoing are hereby incorporated herein by reference in their entirety in a consistent manner. In the event of inconsistencies or contradictions between portions of the incorporated references and this application, the information in the preceding description shall control.

[0055] Descriptions for elements in figures should be understood to apply equally to corresponding elements in other figures, unless indicated otherwise. Although specific embodiments have been illustrated and described herein, it will be appreciated by those of ordinary skill in the art that a variety of alternate and / or equivalent implementations can be substituted for the specific embodiments shown and described without departing from the scope of the present disclosure. Thisapplication is intended to cover any adaptations or variations of the specific embodiments discussed herein. Therefore, it is intended that this disclosure be limited only by the claims and the equivalents thereof.

Claims

What is claimed:

1. A display system comprising: a display region configured to form an image thereacross for viewing by an eye of a viewer and comprising a light emitting region configured to emit light and a light non-emitting region not configured to emit light; a light diffractive layer configured to be between the eye of the viewer and the display region and disposed substantially parallel to, and spaced apart along a thickness direction of the display system from, the display region, the light diffractive layer comprising a light diffractive region configured to diffract light and a light non-diffractive region not configured to diffract light, the light diffractive and non-diffractive regions of the light diffractive layer aligned, and substantially co-extensive in length and width, with the respective light non-emitting and emitting regions of the display region; and a light control layer disposed between the light diffractive layer and the eye of the viewer and having an optical transmittance that varies as a function of an incident angle of an incident light.

2. The display system of claim 1, wherein the light control layer comprises a plurality of alternating light transmissive and light absorbing regions.

3. The display system of claim 1, wherein the light diffractive region comprises a plurality of substantially parallel linear diffractive elements extending along a same in-plane first direction and arranged along a same in-plane orthogonal second direction.

4. The display system of claim 3, wherein the light diffractive region further comprises a second plurality of substantially parallel linear diffractive elements extending along the in-plane second direction and arranged along the in-plane first direction.

5. The display system of claim 1, wherein a location and an extent of the light diffractive region is selected such that the light diffractive region diffracts light from the light emitting region to directions such that the incident angle of the light incident on the light control layer substantially corresponds to incident angles for which the optical transmittance of the incident light through the light control layer is greater than about 50%.

6. The display system of claim 5, wherein the location and the extent of the light diffractive region is such that the light diffractive region covers no more than about 20% of the light emitting region.

7. An optical system comprising:a display configured to emit an image for viewing by an eye of a viewer and comprising a plurality of spaced-apart light emitting pixels defining one or more non-light emitting regions therebetween; a light control film disposed between the display and the eye of the viewer and having an optical transmittance that varies as a function of an incident angle of an incident light; and a collimation film disposed between the display and the light control film and comprising one or more periodic structures substantially covering, and aligned in a one-to-one correspondence with, the one or more non-light emitting regions; such that light emitted by the light emitting pixels diffractively transmitted by the collimation film and exiting the display system in air toward a viewer after passing through the light control film has a maximum brightness Imax across a continuous angle range that is at least 20 degrees wide that is less than about 0.5 of a normalized brightness profile for the plurality of light emitting pixels without the collimation film and the light control film; and wherein the light control film and the collimation film, in combination, increase an on-axis brightness of the display by at least about 10% when compared to a comparative optical system which is identical except that the comparative optical system does not comprise the collimation film.

8. The optical system of claim 7, wherein no more than about 20% of the one or more periodic structures cover the light emitting pixels.

9. The optical system of claim 7, wherein the light control film comprises a plurality of alternating light transmissive and light absorbing regions.

10. The optical system of claim 7, wherein the one or more periodic structures comprise a plurality of substantially parallel linear diffractive elements extending along a same in-plane first direction and arranged along a same in-plane orthogonal second direction.

11. The optical system of claim 10, wherein one or more periodic structures further comprise a second plurality of substantially parallel linear diffractive elements extending along the in-plane second direction and arranged along the in-plane first direction.

12. A display system comprising: a plurality of light emitting pixels defining a plurality of first inter-pixel regions therebetween, each of the first inter-pixel regions devoid of any light emitting pixels; a light diffractive layer disposed on, and spaced apart along a thickness direction of the display system from, the light emitting pixels and comprising a plurality of light diffractive regions substantially aligned and coextensive with the plurality of first inter-pixel regions in one-to-one correspondence, thelight diffractive regions comprising a first plurality of substantially parallel linear diffractive elements extending along a same in-plane first direction and arranged along a same in-plane, orthogonal, second direction; a light control layer disposed on the light diffractive layer opposite the light emitting pixels and having an optical transmittance that varies as a function of an incident angle of an incident light; such that light emitted by the pixels diffractively transmitted by the light diffractive layer and exiting the display system in air toward a viewer after passing through the light control layer has a maximum brightness Imax across a continuous angle range that is at least 20 degrees wide that is less than about 0.5 of a normalized brightness profile for the plurality of light emitting pixels without the light diffractive layer and the light control layer; and wherein the light control layer and the light diffractive layer, in combination, increase an on- axis brightness of the plurality of light emitting pixels by at least about 10% when compared to a comparative display system which is identical except that the comparative display system does not comprise the light diffractive layer.

13. The display system of claim 12, wherein the light control layer comprises a plurality of alternating light transmissive and light absorbing regions.

14. The display system of claim 12, wherein the light diffractive regions further comprise a second plurality of substantially parallel linear diffractive elements extending along the in-plane second direction and arranged along the in-plane first direction.

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