Display device, display apparatus and display method

Abstract

The embodiment of the present application discloses a display device, a display apparatus and a display method. The display device includes a display module and a plurality of lens arrays stacked in sequence arranged on the light-emitting side of the display module, the display module includes a plurality of pixel islands arranged in an array, the lens array includes a substrate and a cover plate arranged opposite to each other, a first transparent electrode arranged on the side of the substrate facing the cover plate, a second transparent electrode arranged on the side of the cover plate facing the substrate, a liquid crystal layer formed between the first transparent electrode and the second transparent electrode, and a diffraction lens grating, wherein the diffraction lens grating includes a plurality of diffraction lens grating units corresponding to the pixel islands, and the first transparent electrode and the second transparent electrode are used to apply a voltage to the liquid crystal layer so that the refractive index of the liquid crystal molecules of the liquid crystal layer is equal to or not equal to the refractive index of the diffraction lens grating.

Description

Technical Field

[0001] The present application relates to the field of display technology, and more specifically, to a display device, a display apparatus, and a display method. Background Art

[0002] With the development of display technology, 3D display technology has been widely used. Naked eye 3D display technology allows users to not wear any auxiliary equipment, which is a major display method in the future.

[0003] However, existing 3D display devices have the problem of convergence and focal length conflict. This is because the user's pupil is completely covered by a single viewpoint, which causes the single-eye focus depth and binocular convergence depth to be not on the same plane. This is different from the user's visual habits of viewing the real world. Long-term viewing will cause visual fatigue and dizziness in the user. To this end, researchers have proposed multi-viewpoint naked-eye 3D technology, which uses a prism to generate multi-viewpoint images and form a light field display of more than two viewpoints in the user's pupil, solving the problem of convergence and focal length conflict. However, there is a problem with this technology. In order to meet the needs of binocular viewing, the pupil needs to enter more than two viewpoints and the two eyes cannot see the same pixel, resulting in a very small visible space for the 3D display device. Summary of the invention

[0004] The purpose of the present application is to provide a display device, a display apparatus and a display method to solve at least one of the problems existing in the prior art.

[0005] In order to achieve the above objectives, this application adopts the following technical solutions:

[0006] In a first aspect, the present application provides a display device, which includes a display module, and also includes a plurality of lens arrays stacked in sequence and arranged on a light-emitting side of the display module.

[0007] The display module includes a plurality of pixel islands arranged in an array.

[0008] The lens array includes a substrate and a cover plate arranged opposite to each other, a first transparent electrode arranged on the side of the substrate facing the cover plate, a second transparent electrode arranged on the side of the cover plate facing the substrate, a liquid crystal layer and a diffraction lens grating formed between the first transparent electrode and the second transparent electrode, wherein the diffraction lens grating includes a plurality of diffraction lens grating units corresponding to the pixel islands,

[0009] The first transparent electrode and the second transparent electrode are used to apply a voltage to the liquid crystal layer so that the refractive index of the liquid crystal molecules in the liquid crystal layer is equal to or different from the refractive index of the diffraction lens grating.

[0010] The display device provided in the first aspect of the present application realizes closing and opening of the lens array by controlling the refractive index of the liquid crystal molecules in the liquid crystal layer of the lens array to be equal to or not equal to the refractive index of the diffraction lens grating, thereby achieving the purpose of expanding the visible range of the display device.

[0011] In a possible implementation manner, the lens array includes a first diffraction lens grating arranged on a side of the cover plate facing the substrate and / or a second diffraction lens grating arranged on a side of the substrate facing the cover plate.

[0012] In this implementation, the diffraction lens grating can be arranged on the upper layer of the substrate or on the lower layer of the substrate, and the arrangement is diverse, which facilitates the formation of the lens array.

[0013] In a possible implementation, between adjacent lens arrays, a substrate of a lens array far from the display module reuses a cover plate of a lens array close to the display module.

[0014] In this implementation, multiple lens arrays reuse one substrate, which can reduce the size of the display device, simplify the manufacturing process, and save costs.

[0015] In a possible implementation, the display assembly further includes a polarizer disposed between the display module and the lens array.

[0016] In this implementation, the polarizer can assist in the deflection direction of the standard output light, and can also filter out the influence of stray light on the display effect, thereby improving the display effect.

[0017] In a possible implementation, the display module is a liquid crystal display module or an OLED display module.

[0018] In a possible implementation, the display assembly further includes a transparent spacer layer disposed between the display module and the lens array.

[0019] In this implementation, a transparent spacer layer is provided between the display module and the lens array so that the pixel unit is at the focal length of the cylindrical lens, thereby ensuring the 3D display effect of the display device.

[0020] In a possible implementation manner, the long axis direction of the liquid crystal molecules of the liquid crystal layer is parallel to the light transmission axis of the polarizer.

[0021] In this implementation, the long axis direction of the liquid crystal molecules can be perpendicular to the polarization direction of the outgoing light from the pixel island, preventing stray light from affecting the display effect.

[0022] In a possible implementation, the distance between the lens array and the display module and the width of the diffraction lens grating unit are determined according to the visual space and resolution of the designed multi-viewpoint light field display.

[0023] At this time, the implementation method is

[0024] In a possible implementation manner, the length of each pixel in the pixel island is set to one third of the width of the diffraction lens grating unit.

[0025] In this implementation, by setting the length of each pixel in the pixel island to one third of the width of the diffraction lens grating unit, the display device has a balanced display resolution in the horizontal and vertical directions when performing 3D display.

[0026] In a possible implementation, the diffraction lens grating unit is a phase diffraction lens grating unit with N steps, where N is 2. n , n is a positive integer.

[0027] A second aspect of the present application provides a display device, which includes a controller and the display component provided by the first aspect of the present application, wherein the controller is used to control the voltage applied to the first transparent electrode and the second transparent electrode of each lens array.

[0028] The display device provided in the second aspect of the present application controls the voltage applied by the first transparent electrode and the second transparent electrode of each lens array through a controller, thereby achieving the adjustability of the visible space range of the display device and expanding the visible space range of the display device.

[0029] In a possible implementation, the display device further includes an eye tracking module for detecting the position of human eyes, and the controller is used to control the voltage applied to the first transparent electrode and the second transparent electrode of each lens array according to the detection result of the position of human eyes.

[0030] In this implementation, the eye position is detected by an eye tracking module, and the range of the visible space is adjusted in real time based on the eye position to ensure the continuity of the 3D display of the display device.

[0031] The third aspect of the present application provides a display method based on the display device provided in the second aspect of the present application, the display method comprising:

[0032] The voltages applied to the first transparent electrode and the second transparent electrode of one lens array among the plurality of lens arrays are controlled so that the refractive index of the liquid crystal molecules of the liquid crystal layer of the lens array is not equal to the refractive index of the diffraction lens grating of the lens array; and the voltages applied to the first transparent electrode and the second transparent electrode of other lens arrays among the plurality of lens arrays are controlled so that the refractive index of the liquid crystal molecules of the liquid crystal layer of the other lens array is equal to the refractive index of the diffraction lens grating of the other lens array.

[0033] In a possible implementation manner, the display method further includes: detecting a position of a human eye, and determining the lens array according to the position of the human eye.

[0034] The beneficial effects of this application are as follows:

[0035] The technical solution provided in the present application realizes closing and opening of the lens array by controlling the refractive index of the liquid crystal molecules in the liquid crystal layer in the lens array to be equal to or not equal to the refractive index of the diffraction lens grating, thereby achieving the purpose of expanding the visual range of the display device. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] The specific implementation methods of the present application are further described in detail below in conjunction with the accompanying drawings.

[0037] Figure 1 The figure shows the principle diagram of the conflict between binocular convergence and monocular focusing in the prior art.

[0038] Figure 2 A schematic diagram showing the principle of using multiple viewpoints to solve binocular convergence and monocular focusing problems.

[0039] Figure 3 The schematic diagram shows the optical path of the sub-pixel emitted light after passing through the lens array.

[0040] Figure 4a-4b A schematic diagram showing the light field after the sub-pixel emitted light passes through the lens array.

[0041] Figure 5 Schematic diagram showing how light emitted from a sub-pixel enters different human eyes.

[0042] Figure 6 A schematic diagram showing multiple viewpoints formed by sub-pixel emitted light in the pupil.

[0043] Figure 7 A schematic diagram of the structure of a display device provided by an embodiment of the present application is shown.

[0044] Figure 8 A schematic diagram of the structure of a display device provided by an embodiment of the present application is shown.

[0045] Fig. 9A comparison diagram of the sizes of a diffraction lens grating unit and a sub-pixel provided in one embodiment of the present application is shown.

[0046] Fig.10 A schematic diagram of the structure of a display device provided by an embodiment of the present application is shown, in which the first lens array is turned on and the second lens array is turned off.

[0047] Fig.11 A diagram showing the light field effect of a display device provided by an embodiment of the present application when a first lens array is turned on and other lens arrays are turned off.

[0048] Fig.12 A schematic diagram of the structure of a display device provided by an embodiment of the present application is shown, in which the first lens array is closed and the second lens array is opened.

[0049] Fig.13 A diagram showing the light field effect of a display device provided by an embodiment of the present application with the second lens array turned on and other lens arrays turned off.

[0050] Fig.14 A partial top view of a two-step phase diffraction lens grating provided by one embodiment of the present application is shown.

[0051] Fig.15 Partial cross-sectional views of phase diffraction lens gratings with two steps, four steps, and eight steps provided by one embodiment of the present application are shown.

[0052] Fig.16 A schematic diagram showing BM blocking of the non-diffraction grating area is shown.

[0053] Fig.17 A schematic structural diagram of a diffraction lens grating unit provided in one embodiment of the present application is shown.

[0054] Fig.18 A schematic structural diagram of a diffraction lens grating unit provided in one embodiment of the present application is shown.

[0055] Fig.19 A schematic structural diagram of a diffraction lens grating unit provided in one embodiment of the present application is shown.

[0056] Fig. 20 A schematic structural diagram of a diffraction lens grating unit provided in one embodiment of the present application is shown.

[0057] Fig.21 A schematic structural diagram of a diffraction lens grating unit provided in one embodiment of the present application is shown.

[0058] Fig. 22 A schematic diagram showing a display device that switches from 3D display to 2D display when all lens arrays of the display device provided by one embodiment of the present application are closed. DETAILED DESCRIPTION

[0059] In order to more clearly illustrate the present application, the present application is further described below in conjunction with the embodiments and drawings. Similar components in the drawings are represented by the same reference numerals. It should be understood by those skilled in the art that the content specifically described below is illustrative rather than restrictive, and should not be used to limit the scope of protection of the present application.

[0060] With the development of society, the current two-dimensional flat display can no longer meet people's needs in some aspects. People hope that the display can truly restore and display the three-dimensional information of the space. Stereoscopic display technology allows users to get rid of the constraints of the plane and experience an immersive feeling, becoming a hot technology in the current display field.

[0061] Stereoscopic display technology can be divided into two categories: assisted stereoscopic display and naked-eye stereoscopic display. The more mature assisted stereoscopic display currently mainly uses stereo glasses and other devices, and uses deflection, filtering and other principles to present stereoscopic images. The biggest disadvantage of assisted stereoscopic display technology is that it cannot get rid of the constraints of visual aids, the operation is complicated, and users are prone to fatigue. In naked-eye stereoscopic display technology, users are no longer restricted by visual aids such as glasses. The basic principle of mainstream naked-eye stereoscopic display technology is to display a stereoscopic image with parallax on the display screen, and then use gratings such as slit gratings and cylindrical lens gratings as parallax segmentation devices. The user's left and right eyes will receive the stereoscopic image with parallax, and synthesize it in the brain to produce a stereoscopic feeling.

[0062] The cylindrical lens technology is also known as double convex lens or micro cylindrical lens 3D technology. The principle of cylindrical lens 3D technology is to add a layer of cylindrical lens in front of the display screen, so that the image plane of the LCD screen is located on the focal plane of the lens, so that the pixel of the image under each cylindrical lens is divided into several sub-pixels, so that the lens can project each sub-pixel in different directions. So when the eyes watch the display screen from different angles, they see different sub-pixels.

[0063] The cylindrical lens stereo grating is composed of many small cylindrical lenses with exactly the same structural parameters and performance. This feature makes it have a "compression" and "isolation" effect on the image. The cylindrical stereo grating can record many images taken from different angles in the same picture in the form of stripes. When watching, the same cylindrical stereo grating is also used to make the human eyes see two different images of the same scene, so a depth image with a parallax stereo effect is generated in the human mind.

[0064] However, in the current display technology, there is a conflict between convergence and focal length, such as Figure 1As shown, since the pupil is completely covered by a single viewpoint, the eye focuses on the plane of the display screen. However, the 3D sense is produced by the convergence of both eyes outside the screen and the fusion of the brain. As a result, the focus depth of one eye and the convergence depth of both eyes are not on the same plane. This is different from the user's visual habit of viewing the real world. Long-term viewing will cause visual fatigue.

[0065] Light field display with more than two viewpoints of the pupil (multi-viewpoint) can solve the problem of conflict between convergence and focus, such as Figure 2 As shown, for a single eye, since each viewpoint only covers a part of the pupil (less than or equal to half the pupil), the single eye is focused on the stereoscopic image, so that the single eye focusing depth and the binocular convergence depth are on the same plane, just like viewing the real three-dimensional world, without visual fatigue and dizziness.

[0066] However, in order to meet the needs of binocular viewing, the pupil needs to enter more than two viewpoints and the two eyes cannot see the same pixel, resulting in only a small visible space of the display device.

[0067] Therefore, in order to solve the problem of small visible space, some parameters of the lens array need to be designed. The inventors found that the placement height of the lens array and the aperture of the cylindrical lens have a great influence on changing the range of the visible space.

[0068] In a specific example, the relationship between the placement height of the lens array and the aperture of the cylindrical lens and the visible space is described as follows:

[0069] 1. The placement height H of the lens array;

[0070] Design the placement height H of the lens array, such as Figure 3 As shown, it is to make each sub-pixel at a distance L from the display device f The center distance of the light beam projection within the distance is not greater than half of the pupil, so that the imaging viewpoint of the display device in the pupil is multi-viewpoint (more than two viewpoints), where L f It is easy to understand that the far limit is the farthest limit for realizing more than two viewpoints of the pupil, and the multiple viewpoints of the pupil can only be realized within the far limit.

[0071] It should be noted that the placement height H of the lens array is the thickness of the lens array embedded in the display device.

[0072] like Figure 3 As shown, when the light beam emitted by the sub-pixel propagates to the far limit L f At the center distance of the two viewpoints formed by the pupil of the human eye is half of the pupil, that is, Φ / 2. From the geometric relationship in the figure, it can be seen that the placement height H of the lens array is related to the far limit L f The following relationship exists:

[0073]

[0074] Arranged:

[0075]

[0076] Where n is the refractive index of the dielectric layer between the lens array and the sub-pixel (the dielectric layer is generally a transparent filler), P pixel is the row spacing of the sub-pixels arranged in the array, and Φ is the diameter of the pupil.

[0077] Based on the above formula, it can be concluded that cylindrical lenses placed at different heights have different far limits.

[0078] For example, when n = 1.5, P pixel =14μm, Φ=4mm, H=5.25mm, we get L f =500mm, that is, when the distance between the human eye and the display device is ≤500mm, multiple viewpoints of the pupil can be achieved.

[0079] When other parameters remain unchanged, changing the placement height H of the lens array can change the distance limit L f For example, when H = 5.775 mm, we get L f =550mm, that is, when the distance between the human eye and the display device is ≤550mm, multiple viewpoints of the pupil can be achieved.

[0080] It should be noted that although increasing the placement height of the lens array can increase the far limit distance, thereby achieving the purpose of expanding the visible space range, as the placement height increases, it means that the volume of the display device also continues to increase. Therefore, in actual application, factors such as the volume of the display device should be considered and the appropriate placement height should be appropriately selected.

[0081] 2. The aperture of the lens array

[0082] The aperture of the lens array is designed to make the visual space of multiple viewpoints continuous. The visual space continuity can be divided into two directions: ① horizontal continuity (the direction parallel to the plane of the display device); ② vertical continuity (the direction perpendicular to the plane of the display device).

[0083] ①Horizontal continuous

[0084] In order to make the visible space continuous in the horizontal direction, the row spacing of the lens array is designed to be an integer multiple of the sub-pixels, and the sub-pixel groups that are combined and have the same row spacing as the lens array are called pixel islands.

[0085] It should be noted that the pixel island is the part of the display module used for display. Usually a pixel island contains several to dozens of pixel units. The pixel island emits light when powered on, for example, red, blue and green. In the present embodiment, the pixel unit used for display in the pixel island is an organic light-emitting diode (OLED). It can be understood that the pixel unit in the pixel island is a pixel unit of an OLED device, which is only a specific example in the present embodiment and does not constitute a limitation. It can also be a pixel unit of other display elements that can be used for display, such as a pixel unit of an LCD, etc., which is not exhaustively listed here.

[0086] As shown in Figure 4 (4b is a partial enlarged view of 4a), the pixel island is tangent to the projection area of ​​each cylindrical lens in the space (the two thick black lines in Figure 4 are the boundary lines of two adjacent viewing areas, they are parallel, and the interval is equal to the diameter of the cylindrical lens, and the actual width of the black line is also equal to the diameter of the cylindrical lens, so any two boundary lines are closely connected), so the human eye can see the pixel island in any area of ​​the space, making the horizontal area continuous.

[0087] ②Vertical continuity

[0088] To realize the light field 3D display of binocular pupils with multiple viewpoints, it is necessary not only to enter multiple viewpoints of the pupils, but also to ensure that both eyes cannot see the same sub-pixel. At the same time, in order to avoid the phenomenon of image arrangement conflict, the average pixel error causes the position where the human eye may appear to be considered not to see the same sub-pixel. Figure 3 There is a near limit Ln in the visible space (the nearest limit at which both eyes cannot see the same sub-pixel at the same time). By designing the aperture of the cylindrical lens, a certain range can be set from the near limit to the far limit. By changing the placement height of the lens array, the various ranges in the visible space can be closely connected, making the longitudinal visible space continuous, thereby achieving the effect of expanding the pupil's multi-viewpoint visible space.

[0089] like Figure 5 As shown, in order to ensure that the same sub-pixel cannot be seen at any possible position of the human eye, it is necessary to ensure that the projection width w of the same sub-pixel at the near limit Ln after passing through different lenses meets the following conditions:

[0090] W=D+Φ+2L n tanε

[0091] Among them, D is the pupil distance (the distance between the two eyes), Φ is the diameter of the pupil, and ε is the average pixel accuracy.

[0092] Combining the geometric relationship in the figure, we can see that:

[0093]

[0094] Arranged:

[0095]

[0096] Among them, P lens is the row spacing of the cylindrical lens. From the above formula, we can know that P lens The larger it is, the smaller Ln is, that is, the larger the row spacing of the cylindrical lens is, the smaller the near limit is.

[0097] It is easy to understand that the range between the near limit and the far limit is the visible range of the pupil multi-viewpoint corresponding to the lens array. Based on the above records, it can be known that the far limit of the pupil multi-viewpoint is only related to the placement height of the lens array. Therefore, after determining the placement height, the row spacing (P lens ) is larger, the far limit of the visible range remains unchanged, and the near limit is smaller, that is, the longitudinal visible space of the pupil multi-viewpoint corresponding to the placement of the height cylindrical lens array is larger.

[0098] However, the row spacing (P lens ) is larger, the lower the light field display resolution is. Figure 6 As shown, since the angles between adjacent image points on each depth of field surface and the human eye are equal, the angular resolution can be used to define the resolution of the light field display image. Specifically:

[0099]

[0100] Among them, α is the resolution angle, L is the viewing distance, and the unit of the resolution angle α is arc minute ('). It is easy to understand that the smaller the value of the resolution angle α, the higher the angular resolution. For example, if the resolution angle is 1', then there are 60 pixels in a 1-degree field of view; if the resolution angle is 2', then there are 30 pixels in a 1-degree field of view, and the resolution of 60 pixels is higher than that of 30 pixels. That is, the smaller the value of α, the higher the resolution of the light field display image. From the above formula, it can be seen that when the viewing distance L is constant, the row spacing (P lens ) is smaller, the smaller the α value is, and the higher the resolution of the light field display image is.

[0101] It can be seen that although the row spacing of the cylindrical lens (P lens ) can expand the vertical visual space of the pupil's multi-viewpoints, but the row spacing of the cylindrical lens (P lens ) is larger, the lower the light field display resolution is. lens ) can be selected based on the actual application scenario.

[0102] It is easy to understand that the row spacing of the cylindrical lenses is the aperture of the lens array.

[0103] Based on the above examples, it can be known that no matter whether the placement height of the lens array or the aperture of the lens array is modified, the range of the visible space of the display device can be changed.

[0104] Based on the above design principles, such as Figure 7 As shown, an embodiment of the present application provides a display device, which includes a controller and a display component.

[0105] The display assembly includes a display module and a plurality of stacked lens arrays arranged on the light-emitting side of the display module.

[0106] The display module includes a plurality of pixel islands arranged in an array.

[0107] like Figure 8 As shown, the plurality of lens arrays each include a substrate and a cover plate arranged opposite to each other, a first transparent electrode arranged on the side of the substrate facing the cover plate, a second transparent electrode arranged on the side of the cover plate facing the substrate, a liquid crystal layer formed between the first transparent electrode and the second transparent electrode, and a diffraction lens grating, wherein the diffraction lens grating includes a plurality of diffraction lens grating units corresponding to the pixel islands,

[0108] The first transparent electrode and the second transparent electrode are used to apply a voltage to the liquid crystal layer so that the refractive index of the liquid crystal molecules of the liquid crystal layer is equal to or different from the refractive index of the diffraction lens grating.

[0109] As mentioned in the above example, in order to make the visible space continuous horizontally, the row spacing of the cylindrical lens needs to be an integer multiple of the sub-pixels. Fig. 9 As shown, in some embodiments, the length of each pixel in the pixel island is set to one third of the width of the diffractive lens grating unit.

[0110] It should be noted that the diffraction lens grating unit width may also be designed according to the length of the sub-pixel, that is, the diffraction lens grating unit width is set to three times the length of each pixel in the pixel island.

[0111] Exemplarily, liquid crystal is an organic compound or a mixture of multiple organic compounds. Liquid crystal has a special state. On the one hand, it is like a liquid and has fluidity. On the other hand, it is like a crystal. The molecules are arranged relatively neatly in a certain direction and have anisotropy. Based on this characteristic, the liquid crystal is unstable. Changes in the external environment, such as temperature, electric field, etc., will cause changes in the arrangement of liquid crystal molecules and change its optical properties.

[0112] For example, when no electricity is applied, the liquid crystal molecules are in a high refractive index state; when a voltage is applied to both ends of the liquid crystal, the liquid crystal molecules will be in a low refractive index state. This is because when a voltage is applied to the transparent electrodes arranged at both ends of the liquid crystal layer, the vertical electric field between the electrodes makes the liquid crystal molecules stand up, and the long axis direction of the liquid crystal molecules is perpendicular to the polarization direction of the light, so that the liquid crystal layer is in a low refractive index state at this time.

[0113] Based on this, reference Figure 8 When the first transparent electrode and the second transparent electrode apply voltage to the liquid crystal layer, the long axis direction of the liquid crystal molecules is perpendicular to the polarization direction of the light, so that the liquid crystal layer is in a low refractive index state at this time. In this way, the refractive index of the liquid crystal molecules in the liquid crystal layer is not equal to the refractive index of the diffraction lens grating. The diffraction lens grating directionally modulates the outgoing light to realize the opening of the lens array.

[0114] On the contrary, when no voltage is applied between the first transparent electrode and the second transparent electrode, the liquid crystal layer is in a high refractive index state, and the diffraction lens grating has the same refractive index as the liquid crystal layer, which is equivalent to the liquid crystal layer and the diffraction lens grating being integrated, and the entire lens array layer only acts as a flat glass, thereby achieving the closure of the lens array.

[0115] like Fig.10 As shown, in some embodiments, the display assembly further includes a polarizer disposed between the display module and the lens array, which can screen the deflection direction of the output light of the display module to be parallel to the transmission axis direction of the polarizer. In addition, the long axis direction of the liquid crystal molecules of the liquid crystal layer is initially aligned to be parallel to the transmission axis of the polarizer, ensuring that the long axis direction of the liquid crystal molecules is parallel to the polarization direction of the output light of the pixel island, thereby preventing stray light from affecting the display effect.

[0116] In a specific example, the controller is used to control the voltage applied to the first transparent electrode and the second transparent electrode of the lens array.

[0117] In a specific example, refer to Fig.10 As shown, the first and second transparent electrodes of the first lens array are powered by the controller, and the vertical electric field between the electrodes makes the liquid crystal molecules stand up, and the long axis direction of the liquid crystal molecules is perpendicular to the polarization direction of the light, and the first liquid crystal layer is in a low refractive index state, that is, the first lens array is turned on; the third and fourth transparent electrodes of the second lens array are not powered, and the second liquid crystal layer is in a high refractive index state, and the refractive index of the second liquid crystal layer is equal to the refractive index of the second diffraction lens grating unit, that is, the second lens array is closed, forming as shown in FIG. Fig.11 The light field display shown achieves more than two viewpoints of the pupil at a relatively close distance.

[0118] refer to Fig.12As shown, the first and second transparent electrodes of the first lens array are not powered by the controller, the first liquid crystal layer is in a high refractive index state, and the refractive index of the first liquid crystal layer is equal to the refractive index of the first diffraction lens grating unit, that is, the first lens array is closed; the third and fourth transparent electrodes of the second lens array are powered, and the vertical electric field between the electrodes makes the liquid crystal molecules stand up, and the long axis direction of the liquid crystal molecules is perpendicular to the polarization direction of the light, and the second liquid crystal layer is in a low refractive index state, that is, the second lens array is turned on, forming as shown in FIG. Fig.13 The light field display shown achieves more than two viewpoints of the pupil at a relatively long distance.

[0119] It should be noted that in this example Fig.10 and Fig.12 Only a part of the lens array and a part of the display module are illustrated, rather than the entire display device. In this example, only two groups of lens arrays are used as an example for illustration. Without affecting the main concept of the present invention, those skilled in the art are capable of setting other numbers of lens arrays without creative work.

[0120] In some embodiments, the distance between the lens array and the display module (ie, the placement height H) and the width of the diffraction lens grating unit (ie, the aperture of the lens array) are determined according to the visual space and resolution of the designed multi-view light field display.

[0121] In a specific example, how to select the number of lens arrays is described as follows:

[0122] Given that the refractive index of the dielectric layer between the lens array and the sub-pixels is n=1.5 and the row spacing of the sub-pixels is P pixel =14μm, pupil diameter Φ=4mm, average pixel accuracy ε=0.5°, P lens =686μm, then,

[0123] (1) When H = 5.25 mm, the near limit L is obtained n =395.3mm, far limit L f =500mm, then under this parameter setting, the vertical viewing space of the display device is 395.3:500mm;

[0124] (2) When H = 6.3 mm, the near limit L is obtained. n =484.1mm, far limit L f =600mm, then under this parameter setting, the vertical visible space of the display device is 484.1:600mm.

[0125] Therefore, for the aperture P of the cylindrical lens lens=686μm, if the longitudinal visible space of the display device is to be 400:600mm, the pupil multi-viewpoint continuous visible space needs to be switched between two lens arrays with different placement heights, wherein the placement height of the first lens array is H=5.25mm, and the placement height of the second lens array is H=6.3mm. The display device under this design has a light field image resolution of 4.72′ at 500mm, which meets the resolution requirements for the display device.

[0126] When the human eye is within a viewing distance of 400:500mm, the lens array with a placement height of H=5.25mm is turned on, and the lens array with a placement height of H=6.3mm is turned off; when the human eye is within a viewing distance of 500:600mm, the lens array with a placement height of H=6.3mm is turned on, and the lens array with a placement height of H=5.25mm is turned off.

[0127] Thereby, the purpose of expanding the visible space range of the display device is achieved.

[0128] In order to pursue higher light field display resolution, the diameter of the cylindrical lens can be appropriately reduced. Specifically, when other parameters remain unchanged, lens =616μm,

[0129] (1) When H = 4.725 mm, the near limit L is obtained n =397.3mm, far limit L f =450mm, then under this parameter setting, the vertical viewing space of the display device is 397.3:450mm;

[0130] (2) When H = 5.25 mm, the near limit L is obtained n =446.5mm, far limit L f =500mm, then under this parameter setting, the vertical viewing space of the display device is 446.5:500mm;

[0131] (3) When H = 5.775 mm, the near limit L is obtained n =496.7mm, far limit L f =550mm, then under this parameter setting, the vertical viewing space of the display device is 500:550mm;

[0132] (4) When H = 6.3 mm, the near limit L is obtained. n =548.1mm, far limit L f =600mm, then under this parameter setting, the vertical viewing space of the display device is 548.1:600mm;

[0133] Therefore, for the aperture P of the cylindrical lens lens=616μm, if you want to obtain a pupil multi-viewpoint continuous visual space of 400:600mm for the longitudinal visual space of the display device, you need to switch between four lens arrays with different placement heights, where the first lens array has a placement height of H=4.725mm, the second lens array has a placement height of H=5.25mm, the third lens array has a placement height of H=5.775mm, and the fourth lens array has a placement height of H=6.3mm. The display device under this design has a light field image resolution of 4.24′ at 500mm, which is higher than the design with two lens array placement heights.

[0134] When the human eye is within the viewing distance of 400:450mm, the lens array with a placement height of H=4.725mm is turned on, and the lens arrays with other placement heights are turned off;

[0135] When the human eye is within the viewing distance of 450:500mm, the lens array with a placement height of H=5.52mm is turned on, and the lens arrays with other placement heights are turned off;

[0136] When the human eye is within the viewing distance of 500:550mm, the lens array with a placement height of H=5.775mm is turned on, and the lens arrays with other placement heights are turned off;

[0137] When the human eye is within the viewing distance of 550:600 mm, the lens array with a placement height of H=6.3 mm is turned on, and the lens arrays with other placement heights are turned off.

[0138] It is easy to understand that the diffraction lens grating unit in the lens array is the main component for realizing 3D display. After designing the placement height and aperture of the lens array, in order to realize 3D display, it is necessary to reduce the pixel light divergence angle so that the sub-pixel projection width is smaller than half the pupil. The pixel needs to be designed on the focal plane of the cylindrical lens. Therefore, it is necessary to design the parameters of the diffraction lens grating based on the set placement height and aperture of the lens array.

[0139] Specifically, there is the following relationship between the focal length of the diffractive lens and the placement height:

[0140]

[0141] Wherein, n is the refractive index of the dielectric layer between the lens array and the sub-pixel. In order to ensure that the sub-pixel is located at the focal length of the lens and realize 3D display of the display device, the parameters of the diffraction lens grating need to be designed.

[0142] The dielectric layer is generally a transparent spacer, and generally an organic adhesive layer (various transparent adhesives) or a transparent substrate (PET or glass) can be selected.

[0143] In the diffraction rod lens array, the diffraction rod lens grating structure of a lens unit is as follows: Fig.14 and 15 As shown, it is composed of a phase diffraction grating and is made on an upper substrate or a lower substrate in a liquid crystal layer.

[0144] Specifically, Fig.14 A partial top view of a two-step phase diffraction lens grating is shown. Fig.15 Partial cross-sectional views of phase diffraction lens gratings with two steps, four steps and eight steps are shown. The diffraction efficiency of diffraction lenses with different number of steps is different. The more steps there are, the higher the diffraction efficiency is, but the more difficult the process is. In this embodiment, a phase diffraction lens with eight steps is preferred.

[0145] Fig.14 In the embodiment, the diffraction lens includes the first to the Mth annular phase grating units, where M is a positive integer. Each grating unit includes N=2^m (m=1, 2, 3, ...) steps, the phase difference between adjacent steps is 2π / N, and the step height is:

[0146]

[0147] Where λ is the wavelength of the incident light (when the incident light is white light, λ is usually taken as 555nm, n e is the high refractive index of the liquid crystal molecule (also called the anomalous light refractive index, the refractive index of linearly polarized light parallel to the long axis of the liquid crystal molecule), and is also the refractive index of the grating material; n o It is the low refractive index of the liquid crystal molecules (also called the ordinary light refractive index, the refractive index of linear polarized light perpendicular to the long axis of the liquid crystal molecules).

[0148] exist Fig.14 In the phase diffraction lens, let the distance from the edge of the i-th step in the j-th grating unit away from the central symmetry line to the central symmetry line be r j,i , where j is a positive integer less than or equal to M, and i is a positive integer less than or equal to N. In the figure, j is 1-3 and i is 1-2 as an example. According to the properties of the diffractive lens, r j,i It has the following relationship with the focal length f of the diffractive lens:

[0149]

[0150] According to the above formula, the width of each step of the diffractive lens can be deduced as:

[0151] d j,i =r j,i -r j,i-1

[0152] From the step height h, r j,i Relationship with the focal length f of the diffractive lens and the width d of each stepj,i The parameter distribution of the step height and step width of the diffraction cylindrical lens grating at any focal length can be calculated.

[0153] For example, taking the liquid crystal molecule model SLC123320 as an example, the refractive index characteristic of the liquid crystal molecule is: n e =1.821, n o =1.522, Δn=n e -n0=0.299. Combined with the step height h, the design height of each step can be calculated. For example: take λ=555nm, when N=2, h=928.1nm; when N=4, h=464nm; when N=8, h=232nm.

[0154] When the design lens array placement height H = 5.25mm, cylindrical lens diameter P lens = 686μm diffraction rod lens array, according to the relationship between the focal length of the diffraction lens and the placement height, f = 3.5mm is calculated, according to r j,i Relationship with the focal length f of the diffractive lens and the width d of each step j,i The distribution of each step width is obtained.

[0155] For example, for a diffractive lens with N=8 steps, the width distribution of each step is d 1,1 =22.0μm, d 1,2 =9.1μm, d 1,3 =7.0μm, d 1,4 =5.9μm, ..., d 30,8 = 0.7 μm, but the cylindrical lens unit diameter calculated from this is P lens =2*r 30,8 = 683.6μm, and the actual required cylindrical lens unit diameter P lens =686μm, therefore, the margin between the cylindrical lenses needs to be designed as follows Fig.16 The P shown lens =686μm, the non-diffraction grating area is designed to block BM to eliminate the interference of stray light.

[0156] It should be noted that there are many ways to make the diffraction lens grating in the upper substrate or the lower substrate of the liquid crystal layer. Taking the two-layer cylindrical lens array with switchable placement height as an example, it can be made in the following ways: Fig.10 The structure distribution shown in FIG. 1 is that the first diffraction lens grating is made on the lower substrate of the first liquid crystal layer, and the second diffraction lens grating is made on the upper substrate of the second liquid crystal layer; it can also be made according to Fig.17 The first diffraction lens grating shown is manufactured on the lower substrate of the first liquid crystal layer, and the second diffraction lens grating is manufactured on the lower substrate of the second liquid crystal layer; Fig.18The first diffraction lens grating shown is manufactured on the upper substrate of the first liquid crystal layer, and the second diffraction lens grating is manufactured on the upper substrate of the second liquid crystal layer; Fig.19 The first diffraction lens grating shown is manufactured on the upper substrate of the first liquid crystal layer, and the second diffraction lens grating is manufactured on the lower substrate of the second liquid crystal layer; Fig. 20 The upper and lower substrates of each liquid crystal layer shown are made of diffraction lens gratings to form a lens group, correct aberrations, reduce the light divergence angle of the pixel after passing through the cylindrical lens, and improve the light field 3D display quality.

[0157] The display device provided in this embodiment expands the visible space of multi-viewpoint light field display by arranging multiple layers of lens arrays and switching each lens array.

[0158] In some embodiments, the display device further includes an eye tracking module for detecting the position of human eyes, and the controller controls whether voltage is applied to the electrodes of each lens array according to the position of human eyes detected by the eye tracking module.

[0159] It should be noted that the distance between the human eye position detected by the human eye tracking module and the display device can be achieved by setting a threshold. Take setting two lens arrays as an example, as shown in Table 1, which shows a mapping relationship between the human eye position and the lens array switch in the display device.

[0160]

[0161] Table 1 only shows that the display device includes two groups of lens arrays. It is easy to understand that the number of lens arrays can be adaptively added or deleted depending on the distance between the human eye position and the display device.

[0162] It should be noted that if Fig.21 As shown, in the display device provided by this embodiment, when all lens arrays are in the closed state, the light beam emitted by the display module is not modulated, and the entire display device can realize 2D display. Therefore, the display device provided by this embodiment also has the function of switching between 2D display and 3D display.

[0163] In order to better realize pupil multi-viewpoint light field 3D display, the display device can also perform 3D image arrangement processing based on the eye coordinate position provided by the eye tracking module. Fig. 22 As shown, combined with the pixel error, the sub-pixels corresponding to the area where both eyes may appear are turned on, and the corresponding 3D view information is loaded, and the other sub-pixels are turned off, so that 3D display can be achieved.

[0164] It should be noted that Fig. 22 Only the projection view distribution of some sub-pixels of a pixel island in space after passing through two cylindrical lenses is shown.

[0165] Another embodiment of the present application provides a display method of the display device provided in the above embodiment. As shown in the figure, the display method includes:

[0166] The voltages applied to the first transparent electrode and the second transparent electrode of one lens array among the multiple lens arrays are controlled so that the refractive index of the liquid crystal molecules of the liquid crystal layer of the lens array is not equal to the refractive index of the diffraction lens grating of the lens array; and the voltages applied to the first transparent electrode and the second transparent electrode of other lens arrays among the multiple lens arrays are controlled so that the refractive index of the liquid crystal molecules of the liquid crystal layer of the other lens arrays is equal to the refractive index of the diffraction lens grating of the other lens arrays.

[0167] In some embodiments, the display method further includes: detecting a position of a human eye, and determining the lens array according to the position of the human eye.

[0168] It should be noted that the principle and working process of the display method provided in this embodiment are similar to the principle of the above-mentioned display device. The relevant parts can be referred to the above description and will not be repeated here.

[0169] In the description of the present application, it should be noted that the terms "upper", "lower", etc. indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present application and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present application. Unless otherwise clearly specified and limited, the terms "installed", "connected", and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be an indirect connection through an intermediate medium, or it can be a connection between the two elements. For those of ordinary skill in the art, the specific meanings of the above terms in the present application can be understood according to the specific circumstances.

[0170] It should also be noted that, in the description of the present application, relational terms such as first and second, etc. are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Moreover, the terms "include", "comprise" or any other variants thereof are intended to cover non-exclusive inclusion, so that the process, method, article or equipment including a series of elements includes not only those elements, but also includes other elements not explicitly listed, or also includes elements inherent to such process, method, article or equipment. In the absence of further restrictions, the elements defined by the statement "comprise one..." do not exclude the presence of other identical elements in the process, method, article or equipment including the elements.

[0171] Obviously, the above embodiments of the present application are merely examples for clearly illustrating the present application, and are not limitations on the implementation methods of the present application. For ordinary technicians in this field, other different forms of changes or modifications can be made based on the above description. It is impossible to list all the implementation methods here. All obvious changes or modifications derived from the technical solution of the present application are still within the scope of protection of the present application.

Claims

1. A display assembly, comprising a display module, characterized in that: It also includes a plurality of lens arrays stacked in sequence and arranged on the light-emitting side of the display module, The display module includes a plurality of pixel islands arranged in an array. The lens array includes a substrate and a cover plate arranged opposite to each other, a first transparent electrode arranged on the side of the substrate facing the cover plate, a second transparent electrode arranged on the side of the cover plate facing the substrate, a liquid crystal layer and a diffraction lens grating formed between the first transparent electrode and the second transparent electrode, wherein the diffraction lens grating includes a plurality of diffraction lens grating units corresponding to the pixel islands, The first transparent electrode and the second transparent electrode are used to apply a voltage to the liquid crystal layer so that the refractive index of the liquid crystal molecules of the liquid crystal layer is equal to or different from the refractive index of the diffraction lens grating; Between adjacent lens arrays, the substrate of the lens array far away from the display module reuses the cover plate of the lens array close to the display module.

2. The display assembly according to claim 1, characterized in that The lens array includes a first diffraction lens grating arranged on a side of the cover plate facing the substrate and / or a second diffraction lens grating arranged on a side of the substrate facing the cover plate.

3. The display assembly according to claim 1, characterized in that: The display assembly also includes a polarizer arranged between the display module and the lens array.

4. The display assembly according to claim 3, characterized in that: The display module is a liquid crystal display module or an OLED display module.

5. The display assembly according to claim 1, characterized in that: The display assembly further includes a transparent spacer layer disposed between the display module and the lens array.

6. The display assembly according to claim 3, characterized in that: The long axis direction of the liquid crystal molecules in the liquid crystal layer is parallel to the light transmission axis of the polarizer.

7. The display assembly according to claim 1, characterized in that: The distance between the lens array and the display module and the width of the diffraction lens grating unit are determined according to the visual space of the designed multi-viewpoint light field display and the resolution of the multi-viewpoint light field display.

8. The display assembly according to claim 1, characterized in that: The length of each pixel in the pixel island is set to be one third of the width of the diffraction lens grating unit.

9. The display assembly according to claim 1, characterized in that: The diffraction lens grating unit is a phase diffraction lens grating unit with N steps, where N is 2 n , n is a positive integer.

10. A display device, characterized in that: The device comprises a controller and a display assembly as claimed in any one of claims 1 to 9, wherein the controller is used to control the voltage applied to the first transparent electrode and the second transparent electrode of each lens array.

11. The display device according to claim 10, characterized in that: The device also includes an eye tracking module for detecting the position of human eyes, and the controller is used to control the voltage applied by the first transparent electrode and the second transparent electrode of each lens array according to the detection result of the position of human eyes.

12. A display method based on the display device according to claim 10, characterized in that: include: Controlling the voltages applied to the first transparent electrode and the second transparent electrode of a lens array among the plurality of lens arrays so that the refractive index of the liquid crystal molecules of the liquid crystal layer of the lens array is not equal to the refractive index of the diffraction lens grating of the lens array; The voltages applied by the first transparent electrode and the second transparent electrode of other lens arrays among the plurality of lens arrays are controlled so that the refractive index of the liquid crystal molecules of the liquid crystal layer of the other lens array is equal to the refractive index of the diffraction lens grating of the other lens array.

13. The display method according to claim 12, characterized in that: The method also includes: detecting the position of a human eye, and determining the lens array according to the position of the human eye.

Images