Display device for enhancing resolution of an image

Abstract

Display device (1) for a motor vehicle, wherein the display device (1) is arranged to display an image (11) consisting of multiple sub-images (12), the display device (1) comprises a micro LED array (2) and a shifting unit (3), the micro LED array (2) is arranged to display the sub-images (12) sequentially in time, the shifting unit (3) is arranged to shift the sub-images (12) with respect to each other, wherein the sub-images (12) consist of sub-pixels (13), each sub-pixel (13) of a sub- image (12) is next to a sub-pixel (13) of a different sub-image (12) in the displayed image (11), and neighboring sub-pixels (13) of different sub-images (12) represent a display pixel (14) of the displayed image (11), wherein the display device (1) comprises a fastening structure for fastening the display device (1) to a motor vehicle.

Description

[0001] Display device for enhancing resolution of an image

[0002] The present invention relates to an optical device, particularly for enhancing the resolution of an image.

[0003] Since the very beginning of digital computers and television, visual information is presented on a screen. Over the decades, the increase of computing power lead to a dramatical increase in resolution. Despite the high effort in increasing the resolution to a high density, an emitter in a display device still has the drawback of having a surface not emitting light from edge to edge.

[0004] A surface of the emitter can be split into two surface areas. The one surface area emits light and the other surface area does not, it is dark. The dark surface area is the space where e.g. the connectors are placed. The ratio between the surface area emitting the light and the total surface area of the emitter is the fill factor. Until today, the fill factor is less than 100%. That means, the emitter surface consists of an area, which does not contribute to the emitted light. Light emitting devices for a display, in particular a head mounted display, require a high fill factor to enable representation of high-quality images.

[0005] In addition to the ever-increasing resolution, the miniaturization progresses steadily requiring increasingly higher demands on the production of each emitter.

[0006] In display devices for motor vehicles, micro LED arrays with multiple emitters are typically used. Micro LED arrays have, however, a poor fill factor of 50% - 70%, which results in large dark areas between the light emitting areas. Hence, a lack of image quality is perceptible, in particular when the micro LED arrays are close to the eye of a viewer, like in a motor vehicle. Display devices are increasingly being used in the automotive sector for displaying or projecting images onto the environment of a motor vehicle, particularly onto the road, so as to deliver information to the driver of the motor vehicle. At the same time, displayed images on the road enable communication between different motor vehicles, while reducing safety risks arising from glare between different motor vehicles, or form a motor vehicles to a pedestrian. Moreover, devices for motor vehicles are more and more used for personalized contents, for example by means of messages displayed or projected onto the terrain below a door of the motor vehicle which appear upon opening of the door, which are becoming increasingly popular.

[0007] Among others, the present device is based on the consideration, that an improved display device is required, particularly for generating a super resolution image which consumes only a small installation space.

[0008] The present display device is arranged to display an image consisting of multiple sub-images. The display device comprises a micro LED array and a shifting unit. The micro LED array is arranged to display the sub-images sequentially in time. The shifting unit is arranged to shift the sub-images with respect to each other, wherein the sub-images consist of sub-pixels. Each sub-pixel of a subimage is next to a sub-pixel of a different sub-image, and neighboring sub-pixels of different sub- images represent a display pixel of the displayed image, wherein the display device comprises a fastening structure for fastening the display device to a motor vehicle.

[0009] In particular, the display device comprises a small installation space in order to be installed in or on a motor vehicle.

[0010] Via its fastening structure, the display device can be fastened particularly on an outside of the motor vehicle, for example in the area of a front part of the motor vehicle. As such, the displayed images can be displayed or projected in the direction of travel of the motor vehicle, in particular onto a road on which the motor vehicle is moving. Thus, the display device allows to deliver information to the driver of the motor vehicle and enables communication between different motor vehicles, without causing glare between different motor vehicles. The display device can also be mounted to other parts of the motor vehicle than the front part, for example on the rear part of the motor vehicle, or on the bodywork between the front and the rear of the motor vehicle, in order to display or project the displayed images to different areas around the motor vehicle. For example, the display device is mounted to a bottom of a door of the vehicle, such that the displayed image can be displayed or projected onto terrain below the door of the vehicle, when the door is opened. In this case, the displayed image can particularly comprise personalized contents such as messages, which is becoming increasingly popular in the automotive sector.

[0011] Alternatively, the display device can be fastened in or to an interior of the motor vehicle via its fastening structure, in particular a dashboard, a center console, a seat of the motor vehicle, a headrest of a seat of the motor vehicle and / or in the area of a window of the motor vehicle.

[0012] For example, the motor vehicle is a passenger car, particularly an electrically powered passenger car.

[0013] Particularly, the display device is configured for an operation temperature between -40°C and +85°C, more particularly between -40°C and +110°C. Operation within these temperature ranges are possible with state-of-the-art micro LED arrays. As such, the display device is operational also in extreme weather conditions and / or areas of a motor vehicle that experience drastic temperature changes.

[0014] In particular, the display device comprises the micro LED array. The micro LED array consists of a matrix with emitters, wherein the emitters are arranged in rows and columns. Typically the micro LED array comprises several thousand rows and columns of emitters, wherein the emitters are arranged along a repetitive rectangular pattern. Each emitter is arranged to emit visible light of a determinable color and intensity and is separately addressable by means of a control unit.

[0015] In particular, the image displayed by the display device consists of the multiple sub-images. The display device is arranged to display images with an image repetition rate. The image repetition rate is typically 60Hz. The micro LED array of the display device is arranged to emit the subimages with a sub-image repetition rate. Thus, the micro LED array displays the sub-images sequentially in time. The sub-image repetition rate is higher than the image repetition rate, typically 2x, 3x or 4x as high.

[0016] In particular, each emitter of the micro LED array emits light forming a beam. The beam comprises the information of the sub-pixel. Said information consists of intensity and color. The shifting unit has a refractive index larger than 1.0, typically a refractive index of 1.5. The beams hit the shifting unit at a first optical surface. By passing the first optical surface the beams are refracted. Due to the larger refractive index of the shifting unit in relation to the surroundings, the beams are refracted towards a surface normal of the first optical surface. The beams transit the shifting unit by passing a second optical surface of the shifting unit. The second optical surface refracts the light away from a surface normal of the second optical surface leading to refracted beams. The refracted beams are parallel to the incoming beams, which hit the first optical surface. Hence, the beams are laterally shifted.

[0017] Each of the sub-images of a common image is shifted laterally differently by the shifting unit, thus the sub-images are shifted with respect to each other. Each sub-image consists of sub-pixels. Each sub-pixel of a sub-image is next to a sub-pixel of a different sub-image in the displayed image, thus neighboring sub-pixels of different sub-images represent a display pixel of the displayed image. In other words, the sub-images of an image are shifted with respect to each other by the fraction of a display pixel.

[0018] In particular, each of the sub-images comprises slightly different information compared to each other. In a low resolution approximation, however, the information of the sub-images seems to be identical. Hence, the sum of the sub-images leads to a higher resolution image.

[0019] According to an embodiment of the present invention, the micro LED array comprises multiple RGB-emitters.

[0020] In particular, each RGB-emitter is arranged to represent a display pixel of the image by sequentially representing sub-pixels. The shifting unit is arranged to shift the sub-pixels with respect to each other, so that the sub-pixels are displayed sequentially in time in neighboring regions.

[0021] Each RGB-emitter comprises at least one micro LED. Typically, one micro LED emits either red, green or blue light. Typically, one RGB-emitter comprises 3 micro LEDs.

[0022] According to an embodiment of the present invention, the shifting unit comprises a tiltable window element. The light emitted by the micro LED array is transmitted through the tiltable window element. The shifting unit is arranged to shift the sub-images with respect to each other by tilting the window element into different tilting states, whereby the shifting unit has one tilting state per sub-image. In particular, the shifting unit comprises the tiltable window element. The window element may comprise two parallel planar surfaces, wherein one surface of the two planar surfaces is the first optical surface of the shifting unit and the other surface of the two planar surfaces is the second optical surface of the shifting unit. The first optical surface and the second optical surface are always parallel to each other in each of the different tilting states. The first optical surface and the second optical surface are tilted in a fixed relationship to each other into the different tilting states.

[0023] In particular, the RGB-emitters of the micro LED array emit the beams, which are transmitted through the tiltable window element. The beams are shifted laterally by the shifting unit. The beams comprise the information of the sub-pixels of the image. Particularly, the image consists of the multiple sub-images. The shifting unit is arranged to shift the sub-images laterally. For each subimage the lateral shift is different, thus the sub-images are shifted with respect to each other. For each lateral shift the shifting unit is in one of the different titling states leading to one tilting state per sub-image.

[0024] The shifting unit is tilted to each tilting state in a temporal sequence. First, the shifting unit is tilted to the first tilting state and a first sub-image is displayed. Afterwards, the shifting unit is tilted to the next tilting state and a next sub-image is displayed.

[0025] According to an embodiment of the present invention, the displayed image consists of at least two sub-images. The micro LED array has a fill factor of at most 50% along a first direction and the shifting unit is arranged to shift the sub-images along the first direction. The beams emitted by the micro LED array propagate in a propagation direction, wherein the first direction is perpendicular to the propagation direction.

[0026] In particular, the fill factor may be defined as a length fill factor, if the images are shifted in a single direction only. Each RGB-emitter comprises a light emitting portion and a non-emitting portion. The length fill factor is the ratio between a sum of the length of the light emitting portions and total length of the RGB-emitters along that direction. More particular, the length fill factor is at most 50% along the first direction, which is perpendicular to the propagation direction of the beams.

[0027] In particular, the micro LED array is arranged to emit beams, which beams depict at least two subimages. The beams are emitted in the propagation direction.

[0028] The sub-images of a common image are shifted laterally with respect to each other by means of the shifting unit.

[0029] According to an embodiment of the present invention, the displayed image consists of at least three sub-images, preferable at least four sub-images. A surface of the micro LED array has a fill factor of at most 25% and the shifting unit is arranged to shift the sub-images along the first direction and along a second direction being perpendicular to the first direction and being perpendicular to the propagation direction. In particular, the fill factor is defined as a surface fill factor, if the sub-images are shifted along a fist and a second directions, wherein the first and the second directions are obliquely with respect to each other. Each RGB-emitter comprises a light emitting portion and a non-emitting portion. The surface fill factor is the ratio between the surface of the light emitting portions and the total surface of the RGB-emitters, wherein the total surface comprises light emitting portions and non-emitting portions. In particular, the surface fill factor is at most 25%.

[0030] In particular, the at least three sub-images, preferable at least four sub-images are emitted by the micro LED array. The emitted sub-images are shifted by the shifting unit. More particularly, when three sub-images are emitted by the micro LED array, the sub-pixels of an image are shifted with respect to each other, so that the sub-pixel are arranged at edges of an imaginary triangle. When four sub-images are emitted by the micro LED array, the sub-pixels of an image are shifted with respect to each other, so that the sub-pixel are arranged at edges of an imaginary rectangle.

[0031] In particular, the four sub-images form an image, which is displayed by the display device. A display pixel comprises four sub-pixels.

[0032] More particular, the micro LED array may be arranged to emit more than four sub-images. Such micro LED-array is combined with a shifting unit which has more than four tilting states.

[0033] According to an embodiment of the present invention, each sub-pixel has a first length along the first direction and / or a second length along the second direction. The shifting unit is arranged to shift the sub-image along the first direction by at least the amount of the first length, and / or the shifting unit is arranged to shift the sub-image along the second direction by at least the amount of the second length.

[0034] In particular, the shifting unit shifts the sub-image lateral to the emitted beams. The sub-image is shifted by the shifting unit in the first direction, in the second direction or in both directions, in the first direction as well as in the second direction. The lateral shifts in both directions lead to a higher resolution in the first direction as well as to a higher resolution in the second direction.

[0035] Each sub-pixel of the sub-image is arranged such that the first side of the sub-pixel is parallel to the first direction and / or that the second side of the sub-pixel is parallel to the second direction. Each sub-pixel has a first length and / or a second length. The first length is along the first direction, whereas the second length is along the second direction.

[0036] In particular, the shifting unit shifts the beams in the first direction with a lateral offset being at least the amount of the first length. More particular, the shifting unit shifts the beams in the second direction with a lateral offset being at least the amount of the second length. Shifting the beams, respectively the sub-images, laterally with a lateral offset of at least the first length and / or at least the second length leads to a display of the image without overlapping of one of the sub-pixels of one sub-image with one of the sub-pixels of another sub-image. Shifting the sub-images to a larger extent as the first length or as the second length, results in a dark area between the sub-pixels of different sub-images. Thus, a reduced brightness of the final image is precepted. The shift of the sub-images to a lower extent as the first length or as the second length results in an overlap of adjacent sub-pixels. Said overlap may be precepted as a reduced quality of the final image.

[0037] According to an embodiment of the present invention, the window element is arranged to be tilted around a first tilting axis being perpendicular to a propagation direction of the beams.

[0038] In particular, the micro LED array emits the beams in the propagation direction. The propagation direction is the direction, where the beams are traveling along and hit the shifting unit at its first optical surface.

[0039] In particular, the first tilting axis is perpendicular arranged to the propagation direction of the beams. The different tilting states are reached by tilting the window element around the first tilting axis. Thus, different sub-images are shifted by tilting the window element around the first tilting axis into the associated tilting state.

[0040] According to an embodiment of the present invention, the window element is arranged to be tilted around a second tilting axis being perpendicular to the first tilting axis.

[0041] In particular, the window element is arranged to be tilted around the second tilting axis into different tilting states in order to refract the beams for the display of different sub-images.

[0042] Particularly, the window element is arranged to be tilted around the first tilting axis and the second tilting axis. In particular, the second tilting axis is perpendicular to the propagation direction of the beam. The tilting around the first tilting axis and around the second tilting axis leads to the shift of sub-images along a first display direction as well as along a second display direction.

[0043] According to an embodiment of the present invention, each RGB-emitter comprises a red micro LED, a green micro LED and a blue micro LED. At least two of the micro LEDs, red, green or blue, of each RGB-emitter are arranged adjacent to each other. The micro LEDs of the RGB-emitter are arranged such that a person using the display device perceives mixed light of micro LEDs of a common RGB-emitter.

[0044] In particular, the RGB-emitter comprises one micro LED of each color, red, green and blue, thus the RGB emitter comprises a red micro LED, a green micro LED and a blue micro LED. At least two of the micro LEDs are arranged adjacent to each other.

[0045] In particular, four of the micro LEDs form a light emitting area having the shape of a square, thus, the light emitting portion of the RGB-emitter has a square shape, as seen in a top view along the propagation direction.

[0046] According to an embodiment of the present invention, each RGB-emitter comprises a red micro LED, a green micro LED and a blue micro LED. At least all red micro LEDs, all green micro LEDs or all blue micro LEDs of the micro LED array are arranged adjacent to each other. For example the micro LED array may comprise different substrates for different colors of micro LEDs. Thus, one substrate comprises all red, all green or all blue micro LEDs. The shifting unit comprises a tiltable window element. The light of all sub-pixels is transmitted through the tiltable window element, and the tiltable window element is continuous and rigid. Thus, the light emitted by micro LEDs from different substrates is transmitted through a common window element.

[0047] In particular, each RGB emitter comprises a red micro LED, a green micro LED and a blue micro LED. All of the micro LEDs are arranged to form a row, in which the micro LEDs are arranged adjacent to each other. The light emitted by all the RGB-emitters, respectively by the micro LEDs, form the beams. The beams are shifted in relation to its propagation direction by the shifting unit, respectively by the tiltable window element. The shifting unit shifts the beams laterally. Hence, the light emitted by each micro LED is shifted simultaneously by the same amount.

[0048] In particular, the micro LED array is configured to emit white light. To this end, for example, the RGB-emitters can be configured to emit white light by means of a mixture of red, green and blue light components.

[0049] The beams comprise the sub-images. Each sub-image consists of the sub-pixel. The light of all sub-pixels is transmitted through the tiltable window element.

[0050] In particular, the tiltable window element is continuous and rigid. Thus, the first optical surface and the second optical surface are formed in a one pieced continuous manner.

[0051] In a preferred embodiment, the shifting unit of the display device comprises at least one actuator, preferably only one actuator.

[0052] As already explained above, the shifting unit is arranged to shift the sub-images with respect to each other. The shifting unit may comprise a first and a second optical surface, which are moveable with respect to each other, in particular by tilting the first and second optical surface relative to each other about a tilting axis, in particular the first or the second tilting axis, which runs essentially perpendicular to both the first and second optical surface. In this context, the actuator preferably is designed to effect the tilting motion between the first and the second optical surface. Preferably, the actuator is arranged to tilt the window element in order to effect a lateral offset as described above, which is a function of to the tilting angle of the window element.

[0053] The actuator is preferably designed as a magnetic actuator. According to the invention, the magnetic actuator is a device that utilizes a magnetic field to create and transmit a force and / or a torque within the shifting unit and preferably comprises a coil and a magnet. The coil may be a wound wire, which is conductive for electric currents. When a current passes through the coil, it generates a magnetic field that exerts a magnetic force. The strength of the magnetic field and the magnetic force depends on the amount of current passing through the coil. The shifting unit is preferably connected to a control unit, which may be configured to set the current according to the desired tilting angle of the window element. The coil may comprise a core, to enhance the magnetic force and / or torque that may be generated.

[0054] The magnet, preferably a permanent magnet, may be positioned near the coil, in particular within a significant reach of the magnetic field that may be exerted by the coil. The magnetic field generated by the coil thus interacts with the magnet, creating a force of attraction or repulsion between, depending on the orientation of the magnetic poles of the generated magnetic field and the magnet.

[0055] The shifting unit may further comprise a bearing system, which may guide the tilting motion of the window element. This is particularly advantageous because the relative arrangement between coil and magnet does not have to be selected so precisely in order to generate the relative displacement between coil and magnet solely as a function of the relative orientation of the magnetic fields generated by the coil and of the magnet. Rather, the bearing system can contain a bearing by means of which the tilting motion is precisely guided and the relative arrangement between coil and magnet preferably only has to take the direction and / or axis of desired motion into account. Preferably, the window element may be held by at least one elastic element, such as a spring. This is advantageous since an elastic element may exert a restoring force or torque to the window element when it is tilted, forcing it into a nominal position. In particular, the at least one elastic element is arranged such that a tilting motion of the window element is possible about the first and / or the second tilting axis.

[0056] It is within the scope of the invention that the coil is stationary with respect to the tilting motion of the window element to be generated and the magnet moves with the window element or vice versa.

[0057] In a preferred embodiment, the shifting unit comprises a frame, by which the window element is held, wherein the frame has an essentially rectangular or square shape with four corner sections. Furthermore, the shifting unit comprises two springs, by which the frame is mounted in two of its corner sections, wherein the springs each are connected to opposing corner sections of the frame.

[0058] It is within the scope of the invention that the springs are integrally connected to the frame or are designed as separate components. In particular, a rectangular frame comprises two long sides and two short sides, wherein the springs are connected to the long sides in the respective first or last quarter of said long sides respectively.

[0059] In another embodiment, the shifting unit comprises four springs by which the frame is mounted in its four corner sections within the shifting unit. This measure increases the stability of the mechanical connection between the shifting unit and the frame, making the optical device more robust against mechanical vibrations that can occur particularly during operation of a motor vehicle on or in which the display device is mounted. Preferably, the window element comprises a material with a refractive index larger than 1.6. This is particularly advantageous as the achievable lateral offset is also a function of the refractive index. This means that with a refractive index greater than 1.6, a small tilt, in particular about the first and / or the second tilting axis, can be set to achieve the same lateral offset as a window element with a refractive offset less than 1.6.

[0060] In a preferred embodiment, the micro LED array defines a central axis with the window element being arranged along the central axis and a width of the window element is chosen such that the window element covers an angle range of ±30 degrees with respect to the central axis of the micro LED array.

[0061] The aforementioned design of the window element is based on the realization that the desired lateral offset can be generated when the window element covers the aforementioned angular range of 60 degrees in total in an untilted state. It is therefore within the scope of the invention that the distance between the micro LED array and the window element can have a distance that can be adjusted as needed as long as the width of the window element covers the above-mentioned angular range.

[0062] Preferably, the window element comprises two faces, wherein the two faces are arranged on opposite sides of the window element and are substantially parallel to each other. The window element can thus be a substantially flat optical component, which makes it easy to manufacture and cheap to purchase.

[0063] Particularly, at least one of the two faces of the window element comprises a phosphor layer.

[0064] In principle, the invention is not limited to a certain thickness of the window element. However, investigations have shown that it is advantageous if the faces of the window element have a distance between 3mm and 30mm. It is within the scope of the invention that any distance between the faces can be set to any value within the specified range, in particular taking into account the tolerances of common manufacturing processes.

[0065] According to an embodiment, at least one emission surface of the micro LED array through which light is emitted from the micro LED array is at least partially covered by a phosphor layer. The phosphor layer is used to transform the light emitted by the micro LED array into white light that can particularly be projected onto the road around the motor vehicle.

[0066] In another embodiment, the shifting unit comprises a magnet and a coil, wherein the coil is configured to generate a magnetic field configured to tilt the window element with respect to a housing of the display device by magnetic interaction with the magnet. To this end, a current can be applied through the coil in order to generate a time-dependent magnetic field that can be used to repel and attract the magnet depending on a magnetic field direction and -strength of the magnetic field generated by the coil. The magnet can be a permanent magnet. The window element can be tilted about the first tilting axis and / or the second tilting axis. Particularly, the magnet is arranged on the window element or on the frame holding the window element and the coil is arranged on the housing. This simplifies the power supply and -control of the coil by means of the control unit, which can be likewise arranged in the housing together with electrical wires for power supply and -control of the coil.

[0067] Alternatively, the magnet is arranged on the housing and the coil is arranged on the window element or on the frame holding the window element.

[0068] The term “to be arranged on” can be interpreted particularly as “arranged on top of” and “form part of’, such that for example the coil can particularly be arranged on top of the housing or it can form part of the housing.

[0069] In particular, the magnet exhibits a magnetization direction oriented perpendicular to a longitudinal extension direction of the window element. Particularly, the magnet faces the coil with exactly one of its magnetic poles. This measure realizes a strong magnetic interaction between the respective pole of the magnet facing the coil and the magnetic field of the coil, whose strength and particularly polarity can be changed with time to tilt the window element with respect to the housing.

[0070] In an embodiment, the magnet is arranged such on the window element or on the frame holding the window element that the magnet can be tilted at least partially into and out of the coil. Inside the coil the magnetic field generated by the coil is at its maximum, realizing a strong magnetic interaction between the magnet and the coil when current flows through the coil, which improves the energy-efficiency of the tilting of the window element by means of the coil.

[0071] According to another embodiment, the magnet is attached to the window element or to the frame holding the window element via an inside of a U-shaped yoke facing the coil.

[0072] In another embodiment, the coil is comprised by a printed circuit board (PCB). The coil can be embedded in the printed circuit board. Alternatively, a gap, particularly an air gap can be formed at an inside of the coil, such that the magnet can be tilted at least partially into and out of the coil of the PCB.

[0073] Further advantages and applied refinements and developments of the display device emerge from the following exemplary embodiments illustrated in connection with the figures.

[0074] Figure 1 shows a basic principle of a display device of the present invention.

[0075] Figure 2 shows a first exemplary embodiment of a present display device with two tilting states of a shifting unit. Figure 3 shows a second exemplary embodiment of a present display device with two tilting axes and with three tilting states of a shifting unit.

[0076] Figure 4 shows the second exemplary embodiment of a present display device with two tilting axes and with four tilting states of the shifting unit.

[0077] Figure 5 shows a third exemplary embodiment of a present display device with a micro LED array having 8 x 8 RGB-emitters displaying four sub-images.

[0078] Figure 6 shows four sub-images with four sub-pixels each, which are summed up in time.

[0079] Figure 7 shows a micro LED array with RGB-emitters comprising micro LEDs.

[0080] Figure 8 a schematic view of an arrangement of a micro LED array and a window element, which is untilted according to view a) and which is tilted according to view b).

[0081] Figure 9 shows an exemplary design of a shifting unit in a front view a) and a back view b).

[0082] Figure 10 shows the exemplary design of the shifting unit in a cross section.

[0083] Figure 11 shows embodiments with a coil arranged on the housing of the display device and a magnet arranged on the window element or the frame holding the window element for tilting the window element with respect to the housing field, wherein the coil is part of a printed circuit board a) and wherein the magnet and the coil realize a permanent magnetic electromagnetic actuator.

[0084] Identical, similar or identically acting elements are provided with the same reference symbols in the figures. The figures and the proportions of the elements shown in the figures among one another are not to be considered to scale, unless units are explicitly stated. Rather, individual elements can be shown in an exaggerated size for better representation and / or for better comprehensibility.

[0085] Figure 1 shows a basic principle of a display device 1 of the present invention. The display device 1 comprises a micro LED array 2 and a shifting unit 3. The micro LED array 2 is arranged to emit beams 20 comprising information of an image 11. The beams 20 are emitted into a propagation direction. The shifting unit 3 is arranged to shift the beams 20 lateral to the propagation direction. The propagation direction is the direction, where the beams 20 are traveling along and hit the shifting unit at a first optical surface. In figure 1 a lateral offset Ay of the beams 20 is shown. The lateral offset Ay is dependent on an angle 3. The angle $ is the angle of incidence at which the beams 20 hit the first optical surface of the shifting unit 3. The angle of incidence is defined as the angle between the incoming beams 20 and a surface normal of the first optical surface. The larger the angle 3 to a certain degree, the larger the lateral offset Ay. The shifting unit 3 in figure 1 is a window element 5, which is tiltable. The window element 5 consists of a refractive index larger 1.0, in figure 1 the refractive index of the window element 5 is 1.5. The window element 5 in figure 1 consists of two planar surfaces, which are parallel to each other. The first optical surface of the two planar surfaces is hit by the beams 20 at the angle 3. When passing the first optical surface, the beams 20 are refracted towards the surface normal of the first optical surface and after passing the second optical surface of the two planar surfaces, the beam 20 is refracted away from a surface normal of the second optical surface. Both transitions, which resulted in refracting the beams 20, lead to the lateral shift of the beams 20.

[0086] The image 11 in figure 1 is displayed with a lateral offset Ay. For clarity reasons an image 11 with angle 3=0 is shown as well. The micro LED array 2 consists of RGB-emitters 4, in figure 1 the micro LED array 2 consists of 2 x 2 RGB-emitters 4.

[0087] Each RGB-emitter 4 comprises an area, which emits light, and an area, which does not emit light. The latter area is a dark area where the connectors are placed, for example. The ratio between the light emitting surface area of the RGB-emitter 4 and the total surface area of the RGB-emitter 4 is defined as surface fill factor. In figure 1 the surface fill factor is 25%.

[0088] Figure 2 shows a first embodiment of the present display device 1. The micro LED array 2 consists of 2 x 2 RGB-emitters 4 emitting the beams 20 comprising information of the image 11. The beams 20 are emitted in the propagation direction hitting a first optical surface of the shifting unit 3. The shifting unit 3 in figure 2 is a window element having two parallel planar surfaces, the first optical surface and a second optical surface, which refract the beams 20 such that the beams 20 are lateral shifted.

[0089] The shifting unit 3 is tiltable around a first tilting axis 15. The first tilting axis 15 is arranged perpendicular to the propagation direction. The shifting unit 3 is tiltable into different tilting states around the first tilting axis 15. Two tilting states are shown in figure 2. In each tilting state the beams 20 are laterally shifted. The lateral shift is different for each tilting state of the shifting unit 3.

[0090] The image 11 displayed by the display device 1 consists of multiple sub-images 12. Each subimage 12 is associated with a tilting state of the shifting unit 3. In figure 2 two tilting states are shown leading to a display of two sub-images 12. The two displayed sub-images 12 resulting from the two tilting states are spaced apart by a length being equal to a first side of the light emitting portion of the RGB-emitter 4. The first side of the light emitting portion of the RGB-emitter 4 is parallel to the direction in which the beams 20 are laterally shifted.

[0091] The shifting unit 3 is tilted into each tilting state in a temporal sequence. First, the shifting unit 3 is tilted into the first tilting state and a first sub-image 12 is displayed. Afterwards, the shifting unit 3 is tilted into the second tilting state and a second sub-image 12 is displayed. In figure 2 the beams 20 carry the same information in both titling states, thus resulting in two sub-images 12 with identical information for each sub-pixel 13. Figure 3 shows a second embodiment of the present display device 1. The display device 1 in figure 3 comprises the micro LED array device having 2 x 2 RGB-emitters 4 and the shifting unit 3 shifting the beams 20, which are emitted by the micro LED array 2. Compared to the first embodiment in figure 2, the display device 1 of the second embodiment in figure 3 comprises a second tilting axis 16. The second tilting axis 16 is arranged perpendicular to the first tilting axis 15 and perpendicular to the propagation direction. The shifting unit 3 is tiltable into different tilting states around the first tilting axis 15 as well as tiltable into different tilting states around the second tilting axis 16. Two tilting states around the first tilting axis 15 are shown in figure 3. In each tilting state the beams 20 are laterally shifted. The lateral shift is different for each tilting state of the shifting unit 3. A third tilting state, which is a tilting state around the second tilting axis 16, is just indicated by an additional arrow. Each tilting state leads to a different shift of the beams 20. While the tilting around the first tilting axis 15 leads to a shift of the beams 20 along a first direction, the tilting around the second tilting axis 16 leads to a shift of the beams 20 along a second direction, which is perpendicular to the first direction and perpendicular to the propagation direction of the beams 20.

[0092] The shifting unit 3 in figure 3 is tilted into the three different tilting states leading to three different sub4mages 12. The shifting unit 3 is tilted to each tilting state in a temporal sequence. Firstly, the shifting unit 3 is tilted to the first tilting state and a first sub-image 12 is displayed. Secondly, the shifting unit 3 is tilted to the second tilting state and a second sub-image 12 is displayed. Thirdly, the shifting unit 3 is tilted to the third tilting state and a third sub-image 12 is displayed. In each tilting state of figure 3 the beams 20 carry different information resulting in three sub-images 12 having different information. Thus, the sub-pixel 13 of one sub-image 12 carries different information as the sub-pixel 13 of another sub-image 12, as indicated in figure 3 by the different colors of the sub-pixels 13.

[0093] Figure 4 shows the second embodiment of the present display device 1 of figure 3. The beams 20 are emitted by the micro LED array 2 and are shifted by the shifting unit 3 lateral to the propagation direction of the beams 20. The display device 1 comprises the first tilting axis 15 and the second tilting axis 16, each being perpendicular to the propagation direction. The first tilting axis 15 and the second tilting axis 16 are both perpendicular to each other.

[0094] In figure 4 the shifting unit 3 is tilted in four different tilting states. In two of the four tilting states the shifting unit 3 is tilted around the first tilting axis 15, whereas in the other two of the four tilting states the shifting unit 3 is tilted around the second tilting axis 16. In figure 4 only the two tilting states around the first tilting axis 15 are shown, the other two tilting states are indicated by a respective arrow of the associated refracted beams 20.

[0095] Each tilting state leads to a different sub-image 12. The sub-images 12 consist of sub-pixels 13. Each sub-pixel 13 of one of the four sub-images 12 is next to a sub-pixel 13 of a different subimage 12 of the four sub-images 12 in the displayed image 11. Adjacent sub-pixels 13 of different sub-images 12 represent a display pixel 14 of the displayed image 11. In figure 4 each sub-pixel 13 has a square shape and the display pixel 14 consists of four sub-pixels 13 forming a square shape as well.

[0096] Each sub-image 12 carries a different information in relation to another sub-image 12, thus the sub-pixels 13 forming a display pixel 14 consist of different information as well. However, in the approximation of low resolution, the information of the sub-pixels 13 in a display pixel 14 is identical. This slight change in information in the sub-pixels 13 of a display pixel 14 results in a higher resolution of the displayed image 11.

[0097] In figure 5 a micro LED array 2 of a third embodiment of the present display device 1 is shown. The micro LED array 2 in figure 5 consists of 8 x 8 RGB-emitters 4. The RGB-emitters 4 are arranged to display an image 11 with the size of 8 x 8 display pixels 14. The image 11 consists of multiple sub-images 12. In figure 5 four such sub-images are shown. Each sub-image 12 consists of subpixels 13. Each of the sub-images 12 in figure 5 has the size of 8 x 8 sub-pixels 13. The temporal sum of the sub-images 12 results in the displayed image 11. Thus, one sub-pixel 13 of a first subimage 12 together with one sub-pixel 13 of a second sub-image 12 together with one sub-pixel 13 of a third sub-image 12 and together with one sub-pixel 13 of a fourth sub-image 12 form a display pixel 14. Hence, two sub-pixels 13 are arranged adjacent to each other, respectively.

[0098] In figure 6 four sub-images 12 are shown resulting in a displayed image 11. Each sub-image 12 has a size of 2 x 2 sub-pixels 13. For reason of clarity each sub-image 12 is shown in front of a micro LED array 2. The lateral shifts of the sub-images 12 vary to each other. The displayed image 11 consists of four display pixels 14. The four sub-images 12 lead to display pixels 14 being each the sum of four sub-pixels 13.

[0099] The sub-pixels 13 in the first row of each sub-image 12 in figure 6 carry the same information. The sub-pixels 13 in the second row of each sub-image 12 carry different information, visualized in figure 6 by the darker color in the sub-pixels 13 of the latter sub-images 12. In the displayed image 11 the temporal sums of the sub-images 12 are shown. While in the first row of the displayed image 11 the display pixels 14 are homogenous, the display pixels 14 in the second row of the displayed image 11 have different sections, each having different information corresponding to the information of the associated sub-image 12. For clarity reasons overlapping areas are shown in the display pixel 14 for visualizing the sums of the four - In the present invention the micro LED array 2 is arranged to display the sub-images 12 with different information leading to a higher resolution in the displayed image 11.

[0100] In figure 7 a micro LED array 2 is shown. Four of the RGB-emitters 4 are highlighted. Each RGB- emitter 4 has a surface fill factor of 25% leading to a surface fill factor of 25% for the entire micro LED array 2. In figure 7 each RGB-emitter 4 comprises four micro LEDs 6. The micro LEDs 6 emit different light, red, green or blue. The mix of the emitted light leads to an adjustable color.

[0101] The invention is not restricted to the exemplary embodiments by the description based on these. Rather, the invention encompasses every new feature and every combination of features, which in particular includes every combination of features in the patent claims, even if this feature or this combination itself is not explicitly specified in the patent claims or exemplary embodiments.

[0102] Figure 8 shows a schematic representation of the relative arrangement between the micro LED array 6 and the window element in views a) and b).

[0103] As can be seen in view a), the orientation of the micro LED array 2 defines a central axis 21 along which the window element 5 is arranged. As can also be seen from view a), the window element 5 has a substantially planar structure, with its oppositely facing sides being spaced apart in a plane- parallel manner by 5mm. In general, however, the thickness 23 of the window element can be between 3 and 30 mm. Furthermore, the window element 5 and the micro LED array 2 are spaced apart at a distance 24. This distance 24 is chosen such that the width 22 of the window element 5 in relation to the central axis 21 covers an angular range between -0 and + 0. In the present case, 0 is 30°, such that the width 22 of the window element 5 covers an angular range of 60°. In another embodiment, not shown here, the window element 5 could also have a smaller or greater width 22, which is naturally a function of the distance 24 and vice versa if an angular range of 60° shall be covered by the window element 5.

[0104] The window element 5 is made of a material that has a refractive index higher than 1.6. Studies by the applicant have shown that a higher refractive index causes a greater lateral displacement Ay when the window element 5 is tilted. Moreover, the studies have shown that the achievable lateral Ay is a function of the thickness 23 and the tilt of the window element 5. This relationship becomes clear in view b) of Figure 8, because the greater the tilt and thickness 23 of the window element 5, the greater the lateral displacement Ay. The tilting axis may be the first or the second tilting axis 15 or 16 respectively.

[0105] Figure 9 shows a shifting unit 3 which comprises a housing 25 and a frame 26 (see view b)), by which the window element 5 is held. The frame 26 has an essentially rectangular shape with two long sides and two short sides and four corner sections. Furthermore, the shifting unit comprises two spring elements 27, 28, by which the frame 26 is mounted in two of its corner sections in the last quarter of the long sides within the shifting unit. The spring elements 27,28 holding the window element 5 at the frame 26 realize the first tilting axis 15. As such, if the spring elements 27,28 are arranged in the corner section as shown in Fig. 9, the first tilting axis 15 runs diagonally through the window element 5 across the two spring elements 27,28. Alternatively, the two spring elements 27,28 can be arranged opposite of each other at respective central sections of the opposing short sides and / or the opposing long sides of the frame 26. As such, the first tilting axis 15 can extend parallel to the long side or the short side of the frame 26. Additionally, the second tilting axis 16 can be realized in the same fashion by further spring elements, such that the window element 5 is tiltable about the first tilting axis 15 and the second tilting axis 16. As shown in view b) of Figure 9, the spring elements 27, 28 each are connected in opposing corner sections of the frame. Furthermore, the shifting unit 3 comprises an actuator 29, which is used to tilt the window element 5 in the manner described above and which is shown in detail in Figure 10. As also shown in view a) of Figure 9, the shifting unit 3 comprises a control unit 30, that is configured to control the actuator 29 according to a desired tilt about the first or the second tilting axis 15 or 16 respectively.

[0106] As mentioned above, Figure 10 shows the shifting unit 3 in a lateral sectional view. As already described in relation to Figure 9, an actuator 29 is provided by which the frame 26, which holds the window element (not shown here), can be adjusted about a tilting axis, in particular the first and / or the second tilting axis 15, 16.

[0107] The actuator 29 is designed as a magnetic actuator, which utilizes a magnetic field to create and transmit a motion, within the shifting unit 3 and comprises a coil 31 and a magnet 32. The coil 31 is a wound wire, which is conductive for electric currents. When a current passes through the coil 31 , it generates a magnetic field that exerts a magnetic force (not shown). The strength of the magnetic field and the magnetic force depends on the amount of current passing through the coil 31, which is controlled by the control unit 30. The magnet 32 is a permanent magnet, which is mechanically coupled to the frame 26 and is arranged within a significant reach of the magnetic field that may be exerted by the coil 31. The magnetic field generated by the coil 31 interacts with the magnet 32, creating a force of attraction or repulsion. The motion of the magnet 32 is transferred to the frame and is guided by the spring elements that were described with regard to Figure 9.

[0108] Fig. 11a shows an embodiment of the invention with a magnet 32 and a coil 31 for tilting the window element 5. The coil 31 according to the present embodiment is comprised by a printed circuit board (PCB) which is attached, for example glued, to the housing 25 of the display device 1. The magnet 32 is a permanent magnet and attached to the window element 5 or the frame 26 holding the window element 5. As can be seen in Fig. 11a, the magnetization axis of the magnet 32 is oriented perpendicular to a longitudinal extension direction of the window element 5, wherein the south pole of the magnet 32 is facing the coil 31. The window element 5 or the frame 26 holding the window element 5 is pivotable with respect to the housing 25 about the first tilting axis 15. A current controlled by said control unit 30 can be conducted through the coil 31 , which causes a magnetic field which is oriented essentially along the magnetization axis of the magnet 32. By adjusting the current flowing through the coil 31 , the strength and particularly the direction of the magnetic field generated by the coil 31 can be adjusted. As such, the window element 5 can be tilted with respect to the housing 25 by repelling or attracting the magnet 32 by means of the magnetic field caused by the coil 31, depending on the direction and strength of the magnetic field caused by the coil 31.

[0109] Fig. 11b shows another embodiment of the invention with a magnet 32 and a coil 31 realizing a permanent magnetic actuator. According to the present embodiment, the magnet 32 is attached to the window element 5 or the frame 26 holding the window element 5 via a U-shaped yoke 33 comprising or consisting of a soft magnetic material with a relative permeability larger than 100, particularly larger than 500. For example, the soft magnetic material is iron. The yoke 33 provides a return path for the magnetic flux to flow from the south pole to the north pole of the magnet 32.

[0110] As can be seen in Fig. 11b, the window element 5, the yoke 33, the magnet 32 and the coil 31 are arranged such that the magnet 32 can be pivoted to a position inside the coil 31 , where the magnetic field generated by the current flowing through the coil 31 has its maximum, which allows for an efficient tilting of the window element 5 by controlling the current flowing through the coil 31.

[0111] List of reference signs

[0112] 1 display device

[0113] 2 micro LED array

[0114] 3 shifting unit

[0115] 4 RGB-emitter / RGB-emitters

[0116] 5 window element

[0117] 6 micro LED

[0118] 11 image

[0119] 12 sub-image / sub-images

[0120] 13 sub-pixel / sub-pixels

[0121] 14 display pixel

[0122] 15 first tilting axis

[0123] 16 second tilting axis

[0124] 20 beams

[0125] 21 central axis

[0126] 22 width of the window element

[0127] 23 thickness of the window element

[0128] 24 distance between micro LED array and window element

[0129] 25 housing

[0130] 26 frame

[0131] 27 spring element

[0132] 28 spring element

[0133] 29 actuator

[0134] 30 control unit

[0135] 31 coil

[0136] 32 magnet

[0137] 33 yoke

Claims

Claims1. Display device (1) for a motor vehicle, wherein the display device (1) is arranged to display an image (11) consisting of multiple sub-images (12), the display device (1) comprises a micro LED array (2) and a shifting unit (3), the micro LED array (2) is arranged to display the sub-images (12) sequentially in time, the shifting unit (3) is arranged to shift the sub-images (12) with respect to each other, wherein the sub-images (12) consist of sub-pixels (13), each sub-pixel (13) of a subimage (12) is next to a sub-pixel (13) of a different sub-image (12) in the displayed image (11), and neighboring sub-pixels (13) of different sub-images (12) represent a display pixel (14) of the displayed image (11), wherein the display device (1) comprises a fastening structure for fastening the display device (1) to a motor vehicle.

2. Display device (1) according to claim 1, wherein the micro LED array (2) comprises multiple RGB-emitters (4).

3. Display device (1) according to claim 1 or 2, wherein the shifting unit (3) comprises a tiltable window element (5), light emitted by the micro LED array (2) is transmitted through the tiltable window element (5), the shifting unit (3) is arranged to shift the sub-images (12) with respect to each other by tilting the window element (5) into different tilting states, whereby the shifting unit (3) has one tilting state per sub-image (12).

4. Display device (1) according to one of the preceding claims, wherein the displayed image (11) consists of at least two sub-images (12), the micro LED array (2) has a fill factor of at most 50% along a first direction and the shifting unit (3) is arranged to shift the sub-images (12) along the first direction, beams (20) emitted by the micro LED array (2) propagates in a propagation direction, the first direction is perpendicular to the propagation direction.

5. Display device (1) according to one of the preceding claims, wherein the displayed image (11) consists of at least three sub-images (12), preferable at least four sub-images (12), a surface of the micro LED array (2) has a fill factor of at most 25% and the shifting unit (3) is arranged to shift the sub-images (12) along the first direction and a long a second direction being perpendicular to the first direction and being perpendicular to the propagation direction.

6. Display device (1) according to one of the preceding claims, wherein each sub-pixel (13) has a first length along the first direction and / or a second length along the second direction, wherein the shifting unit (3) is arranged to shift the sub-image (12) along the first direction by at least the amount of the first length, and / or wherein the shifting unit (3) is arranged to shift the subimage (12) along the second direction by at least the amount of the second length.

7. Display device (1) according to one of the claims 1 to 4, wherein the window element (5) is arranged to be tilted around a first tilting axis (15) being perpendicular to the propagation direction.

8. Display device (1) according to claim 7, wherein the window element (5) is arranged to be tilted around a second tilting axis (16) being perpendicular to the first tilting axis (15).

9. Display device (1) according to one of the preceding claims, wherein each RGB emitter (4) comprises a red micro LED (6), a green micro LED (6) and a blue micro LED (6) and wherein at least two of the micro LEDs (6), red, green or blue, of each RGB emitter (4) are arranged adjacent to each other.

10. Display device (1) according to one of the claims 1 to 9, wherein each RGB emitter (4) comprises a red micro LED (6), a green micro LED (6) and a blue micro LED (6), wherein at least all red micro LEDs (6), all green micro LEDs (6) or all blue micro LEDs (6) of the micro LED array (2) are arranged adjacent to each other, and the shifting unit (3) comprises a tiltable window element (5), wherein the light of all sub-pixels (13) is transmitted through the tiltable window element (5), and the tiltable window element (5) is continuous and rigid.

11. Display device (1) according to one of the preceding claims, wherein the micro LED array (2) is configured to emit white light, particularly wherein the RGB-emitters are configured to emit white light.

12. Display device (1) according to one of the preceding claims, wherein the shifting unit (3) comprises one actuator (29) or exactly one actuator (29).

13. Display device (1) according to at least claim 3, wherein the window element (5) comprises a material with a refractive index larger than 1.6.

14. Display device (1) according to at least claim 3, wherein the micro LED array (2) defines a central axis (21) with the window element (5) being arranged along the central axis (21) and a width of the window element (5) is chosen such that the window element (5) covers an angle range of ±30 degrees with respect to the central axis (21) of the micro LED (2) array.

15. Display device (1) according to at least claim 3, wherein the window element (5) comprises two faces, wherein the two faces are on the opposite side of the window element (5) arranged and are substantially parallel to each other.

16. Display device (1) according to claim 15, wherein the two faces are at least 3 mm spaced apart from each other and at most 30 mm.

17. Display device (1) according to at least claim 3, wherein the shifting unit (3) comprises a frame (26), by which the window element (5) is held, wherein the frame (26) has an essentially rectangular or square shape with four corner sections and wherein the shifting unit (3) comprises two springs (27, 28), by which the frame (26) is mounted in two of its corner sections within the shifting unit (3), wherein the springs (27, 28) each are connected to opposing corner sections of the frame (26).

18. Display device (1) according to claim 17, wherein the shifting unit (3) comprises four springs by which the frame (26) is mounted in its four corner sections within the shifting unit (3).

19. Display device (1) according to at least claim 12, wherein the actuator (29) is designed as a magnetic actuator.

20. Display device (1) according to one of the preceding claims, wherein at least one emission surface of the micro LED array (2) through which light is emitted from the micro LED array (2) is at least partially covered by a phosphor layer.

21. Display device (1) according to one of the claims 3 to 20, wherein the shifting unit (3) comprises a magnet (32) and a coil (31), wherein the coil (31) is configured to generate a magnetic field configured to tilt the window element (5) with respect to a housing (25) of the display device (1) by magnetic interaction with the magnet (32).

22. Display device (1) according to claim 21 , wherein the magnet (32) is arranged on the window element (5) or on the frame (26) holding the window element (5) and wherein the coil (31) is arranged on the housing (25).

23. Display device (1) according to claim 21 or 22, wherein the magnet (32) exhibits a magnetization direction oriented perpendicular to a longitudinal extension direction of the window element (5).

24. Display device (1) according to one of the claims 22 or 23, wherein the magnet (32) is arranged such on the window element (5) or on the frame (26) holding the window element (5) that the magnet (32) is tiltable at least partially into and out of the coil (31).

25. Display device (1) according to one of the claims 22 to 24, wherein the magnet (32) is attached to the window element (5) or to the frame (26) holding the window element (5) via an inside of a U- shaped yoke (33) and facing the coil (31).

26. Display device (1) according to one of the claims 21 to 25, wherein the coil (31) is comprised by a printed circuit board (PCB).

Images