Large field of view three-dimensional display device

Abstract

The present invention relates to display technology, and in particular to a device for realizing a large viewing angle three-dimensional display of naked-eye three-dimensional images. According to one aspect of the present invention, a large viewing angle three-dimensional display device comprises: a backlight plate, which is configured to convert a light beam emitted by a light source into a first collimated light beam; a spatial light modulator located in the propagation direction of the first collimated light beam, which is configured to load multi-view mixed image information onto the first collimated light beam by amplitude modulation to form a second collimated light beam; and a phase plate located in the propagation direction of the second collimated light beam, which has a diffraction structure, and the diffraction structure is configured to project an image of each viewing angle in the image carried by the second collimated light beam to a corresponding set of observation positions.

Description

Technical Field

[0001] The present invention relates to display technology, and in particular to a large viewing angle three-dimensional (3D) display device for realizing naked-eye three-dimensional (3D) images. Background Art

[0002] With the improvement of living standards and the rapid development of science and technology, realistic visual experience has become people's pursuit of display images, and 3D display technology has emerged. Not only in the traditional display industry, but also in many fields such as multimedia and software development, the development and application of 3D display technology is urgently needed. Traditional 3D display technology requires additional auxiliary equipment (such as 3D glasses, etc.) to observe stereoscopic images, which greatly limits people's viewing freedom. Therefore, the development of naked-eye 3D display technology is the general trend.

[0003] A hologram is an image that carries amplitude and phase information to truly reproduce three-dimensional information. The characteristic of holographic display is that the hologram can reproduce a three-dimensional virtual image or a three-dimensional real image in space. Each point on the hologram transmits information in all directions in space, and each observation point in space can see the entire image. In other words, the image information is converged on the observation point through light field transmission. Therefore, the entire image of different viewing angles can be viewed at different observation points in space without interfering with each other. However, for decades, due to the limitations of holographic recording materials, information volume and technical processes, holographic display has failed to achieve dynamic color naked-eye 3D display with a wide viewing angle.

[0004] The naked-eye 3D display technology based on the parallax principle includes the visual barrier method and the micro-column lens method. In these technologies, a visual barrier screen or a micro-column lens array is set on the surface of the liquid crystal display panel to achieve the separation of images of different viewing angles in space. Since ghost images and stray light are difficult to eliminate, it is easy to cause visual fatigue when observing such 3D images. At the same time, due to the influence of stray light, the viewing angle interval is usually set larger, resulting in incoherent viewing angles, and it is impossible to achieve a jump-free naked-eye 3D display effect. In addition, the existing naked-eye 3D display equipment is large in size and difficult to integrate into small devices such as mobile phones. Summary of the invention

[0005] An object of the present invention is to provide a large-field-of-view three-dimensional display device for realizing naked-eye three-dimensional images, which has the advantages of low manufacturing cost, simple design and compact structure.

[0006] A three-dimensional display device with a large viewing angle according to one aspect of the present invention comprises:

[0007] a backlight panel configured to convert the light beam emitted by the light source into a first collimated light beam;

[0008] a spatial light modulator located in the propagation direction of the first collimated light beam, configured to load multi-view mixed image information onto the first collimated light beam by amplitude modulation to form a second collimated light beam; and

[0009] The phase plate located in the propagation direction of the second collimated light beam has a diffraction structure, and the diffraction structure is configured to project an image of each viewing angle in the image carried by the second collimated light beam to a corresponding set of observation positions.

[0010] Preferably, in the above device, the spatial light modulator includes a first body pixel, each body pixel includes a plurality of sub-pixels, each sub-pixel corresponds to a different viewing angle, and the diffraction structure includes a plurality of micro-structure units, each micro-structure unit is configured to project a light beam from a sub-pixel corresponding to the same viewing angle among the plurality of body pixels of the spatial light modulator to a set of observation positions associated with the sub-pixel.

[0011] Preferably, in the above device, the diffraction structure is implemented by one of the following structures: one-dimensional nanograting, two-dimensional nanograting, spatially multiplexed nanograting, nanograting array and diffractive optical element.

[0012] Preferably, in the above device, the diffraction structure is implemented by a diffraction optical element, and the diffraction efficiency of the diffracted light at the zeroth order of diffraction is minimized by adjusting the structural depth of the diffraction optical element.

[0013] Preferably, in the above device, the backlight panel comprises:

[0014] A light guide plate, comprising a first microstructure located on an upper surface, a lower surface or an inner portion of the light guide plate, the first microstructure having periodically distributed first units, and the light beam emitted by the light source is scattered to the outside of the light guide plate through the first microstructure; and

[0015] The optical film stacked with the light guide plate comprises a second microstructure located on the surface of the optical film, the second microstructure having periodically distributed second units, and the light beam scattered to the outside of the light guide plate by the first microstructure is transformed into the first collimated light beam by the second microstructure.

[0016] Preferably, in the above device, the first unit is one of a microprism, a microlens, a free-form surface lens or a pit.

[0017] Preferably, in the above device, the second unit is one of a microlens, a Fresnel lens or a film lens.

[0018] Preferably, in the above device, the backlight plate further comprises a light shielding plate, which comprises a light shielding structure matching and corresponding to the first microstructure and the second microstructure to filter out stray light emitted from the second microstructure.

[0019] Preferably, in the above device, the shading plate is disposed at one of the following positions: between the light guide plate and the optical film, inside the light guide plate, and inside the optical film.

[0020] Preferably, in the above device, the light source is integrated into the device and located on a side of the backlight panel.

[0021] Preferably, in the above device, the light source is an LED linear array light source.

[0022] Preferably, in the above device, the spatial light modulator is a liquid crystal display unit.

[0023] Preferably, the above device further comprises a light shielding plate located between the spatial light modulator and the phase plate.

[0024] Preferably, in the above device, the light source is a white light source or a three-primary color light source, and the device further comprises a color filter stacked together with the spatial light modulator and the phase plate.

[0025] Preferably, in the above device, the color filter is arranged between the spatial light modulator and the phase plate. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 Schematic diagram of a large-field-of-view three-dimensional display device according to an embodiment of the present invention.

[0027] Figure 2 For application Figure 1 Schematic diagram of the backlight panel of the device shown.

[0028] Figure 3 Another method that can be applied to Figure 1 Schematic diagram of the backlight panel of the device shown.

[0029] Figures 4a-4d For application Figure 1 Schematic diagram of a single microstructure unit of the phase plate in the illustrated embodiment.

[0030] Figure 5a-5c To adopt Figures 4a-4d Schematic diagram of the sub-pixel viewpoint (array) effect of the phase plate composed of microstructure units shown.

[0031] Figure 6 The figure is a schematic diagram showing a multi-viewing angle image display structure for expanding the viewing angle.

[0032] Figure 7 The figure is a schematic diagram showing another multi-viewing angle image display structure for expanding the viewing angle. DETAILED DESCRIPTION

[0033] The purpose of the present invention will be described in detail below with reference to the accompanying drawings.

[0034] Figure 1 Schematic diagram of a large-field-of-view three-dimensional display device according to an embodiment of the present invention.

[0035] Figure 1 The device 10 shown includes a backlight panel 110, a spatial light modulator 120 and a phase plate 130. The backlight panel 110 can be a directional backlight panel, for example. Optionally but not necessarily, the light source 140 can be used as Figure 1 Preferably, the light source 140 can be an LED line array light source.

[0036] See also Figure 1 , the light beam emitted by the light source 140 is converted into a collimated light beam B1 along one or more directions (hereinafter referred to as the first collimated light beam B1) by the backlight panel 110. The spatial light modulator 120 is arranged in the propagation direction of the first collimated light beam B1, and loads the multi-view mixed image information onto the first collimated light beam B1 through amplitude modulation to form a collimated light beam B2 (hereinafter referred to as the second collimated light beam B2). The phase plate 130 is arranged in the propagation direction of the second collimated light beam B2, and uses a microstructure unit (such as a nanostructure unit) to project the image of each perspective in the image carried by the second collimated light beam B2 to multiple corresponding observation positions, so that the effect of naked-eye 3D display can be achieved under a large field of view.

[0037] It should be noted that in this specification, collimated light beams, parallel light beams, directional light beams and convergent light beams propagating in one direction refer to outgoing light beams with a divergence angle half-width within 30°. Preferably, the divergence angle half-width of the outgoing light beam is within 10°.

[0038] Figure 2 According to another embodiment of the present invention, it is applicable to Figure 1 Schematic diagram of the backlight panel of the device shown.

[0039] Figure 2 The directional backlight plate 110 shown includes a light guide plate 111 and an optical film 112. The optical film 112 may be, for example, a micro-nano optical film. Figure 2As shown, a first microstructure 111A having periodically distributed first units (shown as pits in the figure) is formed on the upper surface of the light guide plate 111. The light source 140 is located at the side of the light guide plate 111, and the light beam emitted by the light source enters the light guide plate 111 and is scattered to the outside of the light guide plate 111 by the first microstructure 111A.

[0040] Although Figure 2 The first microstructure 111A shown in FIG. 1 is formed on the upper surface of the light guide plate 111, but it can also be formed on the lower surface or inside the light guide plate 111. Preferably, the size of the first microstructure is between 100 nm and 1 mm. Figure 2 In the directional backlight panel 110 shown, the first unit is exemplarily shown in the form of a pit, but it can also be an optical element in other forms, such as but not limited to a micro prism, a micro lens, a free-form surface lens, etc.

[0041] Continue to see Figure 2 , the optical film 112 is located below the light guide plate 111. The optical film 112 can be stacked with the light guide plate 111 or maintain a certain air gap with the light guide plate 111 (when the refractive index of the optical film is close to or higher than the refractive index of the light guide plate). In addition, a low refractive index layer can be inserted between the light guide plate 111 and the optical film 112 to avoid forming a total reflection condition in the light guide plate. Figure 2 As shown, a second microstructure 112A having a periodically distributed second unit is formed on the surface of the optical film 112. The second microstructure 112A matches the first microstructure 111A in structure, and functions to transform the divergent light beam from the light guide plate 111 into a first collimated light beam B1 emitted in one or more directions. Preferably, the second microstructure 112A adopts a configuration such as a microlens array, a Fresnel lens array, a film lens array, a binary structure light array, etc. The lens unit of the microlens array, the Fresnel lens array or the film lens array can be optimized according to the relative position with the microstructure in the light guide plate to obtain a better collimation or convergence effect. For example, the diameter of each unit or microlens in the optical film 112 can be designed to be larger than the size of the unit or pit structure of the light guide plate 111.

[0042] In this embodiment, plastic or glass can be selected as the material of the light guide plate or microlens, and its refractive index is between 1-2.5. Plastic can be preferably used to make the product lighter and reduce the cost. In addition, the light guide plate 111 can be composed of one material or a plurality of materials with different refractive indices. The light guide plate and the optical film can be made, for example, by grayscale photolithography, laser etching, etc., and can be mass-produced by nanoimprinting.

[0043] Preferably, a light shielding plate may be provided in the backlight panel 110 to filter out unwanted stray light. Figure 3In the backlight shown, a light shielding plate 113 may be provided between the light guide plate and the optical film. The light shielding plate includes a light shielding plate that matches the first microstructure 111A and the second microstructure 112A, so that stray light emitted from the second microstructure can be filtered out. The light shielding plate may be a single-layer or multi-layer independent structure, and may be integrated with any one or more of the light guide plate, the optical film, the spatial light modulator, and the Fresnel lens group to form a functionally complex optical device.

[0044] exist Figure 1 In the illustrated embodiment, the spatial light modulator 120 is used for amplitude modulation, that is, loading multi-view mixed image information. The spatial light modulator may, for example, include a display panel, a driving circuit, a control system, and software control. Depending on the needs of a specific application field, the spatial light modulator may realize monochrome or color display. Preferably, the spatial light modulator 120 may be a liquid crystal display unit. The spatial light modulator 120 may include a plurality of body pixels or amplitude modulated pixels, each body pixel includes a plurality of sub-pixels, and each sub-pixel corresponds to a different viewing angle.

[0045] In the prior art, the image of each sub-pixel from the spatial light modulator is projected by a phase plate to a corresponding single viewing angle or observation position, but it will be seen from the description below that in the present invention, the phase plate projects the image of each sub-pixel of the spatial light modulator to a corresponding set of viewing angles or a set of observation positions, thereby widening the field of view.

[0046] In order to obtain a set of observation positions, in this embodiment, the phase plate 130 has a diffraction structure, which includes a plurality of hoxels. Further, each hoxel of the phase plate 130 includes a plurality of microstructure units, each of which is matched and aligned with a pixel of the view angle image of the spatial light modulator, that is, a light beam corresponding to a sub-pixel of the same view angle from a plurality of hoxels of the spatial light modulator 120 is projected to a set of observation positions associated with the sub-pixel. Preferably, the diffraction structure can be implemented using various structures, such as but not limited to one-dimensional nano-gratings, two-dimensional nano-gratings, spatially multiplexed nano-gratings, nano-grating arrays, and diffractive optical elements (or secondary optical elements).

[0047] Figures 4a-4d For application Figure 1 Schematic diagram of a single microstructure unit of the phase plate in the illustrated embodiment.

[0048] by Figure 4aFor example, the microstructure unit 131 is in the form of a pixel unit, which is divided into 9 grating areas 1a-1i with different periods and / or orientation angles. When light from a sub-pixel of the spatial light modulator 120 arrives, different grating areas will deflect the light to different observation positions, thereby realizing the projection of a light beam of the same viewing angle to multiple observation positions, thereby expanding the field of view.

[0049] The period and orientation angle of the grating region can be determined according to the following grating equation:

[0050] tanφ 1 =sinφ / (cosφ-nsinθ(Λ / λ)) (1)

[0051] sin 2 (θ 1 )=(λ / Λ) 2 +(nsinθ) 2 -2nsinθcosφ(λ / Λ) (2)

[0052] Among them, θ 1 and φ 1 They respectively represent the diffraction angle (the angle between the diffracted light and the negative direction of the z-axis) and the azimuth (the angle between the diffracted light and the positive direction of the y-axis) of the diffracted light, θ and λ respectively represent the incident angle (the angle between the incident light and the negative direction of the z-axis) and the wavelength of the light source, Λ and φ respectively represent the period and orientation angle (the angle between the groove direction and the positive direction of the x-axis) of the nano-diffraction grating, and n represents the refractive index of the light wave in the medium.

[0053] Therefore, once the wavelength of the incident light, the incident angle, the diffraction angle of the diffracted light and the diffraction azimuth are determined, the above formula can be used to calculate the required grating period and orientation angle.

[0054] Another example: Figure 4b The microstructure unit 131 shown adopts the form of grating space multiplexing, which is composed of 9 gratings with different periods and / or orientation angles stacked together. When light from a sub-pixel of the spatial light modulator 120 arrives, different gratings also deflect the light to different observation positions, thereby realizing the projection of the light beam of the same viewing angle to multiple observation positions, thereby expanding the field of view.

[0055] Figure 4c and 4d The microstructure units shown are respectively a two-step diffractive optical element and a multi-step diffractive optical element, which can also deflect light from one viewing angle to different viewing positions.

[0056] Figure 5a-5c To adopt Figures 4a-4dSchematic diagram of the phase plate sub-pixel viewpoint (array) effect composed of microstructure units. The light incident on a single microstructure unit forms multiple visible areas after wavefront transformation. These visible areas can be as follows Figure 5a The strips shown, Figure 5b The ring or Figure 5c Obviously, this expands the horizontal and / or vertical viewing range, so that the observer can observe the information image at the same viewing angle when moving up, down, left, and right.

[0057] Figure 6 The figure is a schematic diagram showing a multi-viewing angle image display structure for expanding the viewing angle.

[0058] Without loss of generality, Figure 6 In the following, a display device with four viewing angles is used as an example for explanation. Figure 6 In the figure, each shaded portion on the phase plate 130 represents a body pixel and includes four microstructure units (e.g., Figures 4a-4d By controlling the orientation angle and / or period of the grating in the microstructure unit or designing the structure of the diffractive optical element according to the light wave diffraction theory, it is possible to Figure 6 As shown, multiple visible areas are formed in the horizontal and vertical directions. Each shaded portion on the phase plate 130 is aligned with the body pixel of the spatial light modulator 120, so that multiple information images of the same viewing angle can be presented in multiple horizontally and vertically arranged visible areas, thereby achieving the effect of expanding the field of view without increasing the refresh display information required by the spatial light modulator.

[0059] Figure 7 The figure is a schematic diagram showing another multi-viewing angle image display structure for expanding the viewing angle.

[0060] Likewise, Figure 7 A display device with four viewing angles is also used as an example for explanation. Figure 7 In the figure, each shaded portion on the phase plate 130 corresponds to a pixel of the spatial light modulator 120 and includes four microstructure units (e.g., Figures 4a-4dThe microstructure unit of the form shown). By controlling the orientation angle and / or period of the grating in the microstructure unit, or designing the structure of the diffractive optical element according to the light wave diffraction theory, a plurality of visible (strip) areas distributed at a certain interval can be formed in the horizontal direction. Each shaded portion on the phase plate 130 represents a body pixel and is matched and aligned with the body pixel of the spatial light modulator 120, thereby presenting a plurality of information images of the same viewing angle in the visible (strip) area arranged at a certain interval. At the same time, the microstructure units of different sub-pixels corresponding to the information images of different viewing angles are sequentially distributed in the horizontal direction, and together form a circularly distributed visible point (line) array area 1-4, thereby achieving the effect of expanding the field of view without increasing the refresh display information required by the spatial light modulator.

[0061] The diffraction efficiency η of a diffractive optical element or a binary optical element can be determined by the following formula:

[0062]

[0063] Where N is the number of steps in the binary optical element and m is the diffraction order.

[0064] In an ordinary diffraction grating, the zero-order diffraction light occupies most of the energy, while the useful +1 or -1 order diffraction light occupies a limited proportion of the energy, which greatly affects the quality and effect of the display. In this embodiment, preferably, by adjusting the structural depth of the diffraction optical element on the phase plate, the diffraction efficiency of the diffraction light at the diffraction order of m=0 can be minimized (e.g., equal to 0), that is, the zero-order diffraction light is completely eliminated, so that the energy is mainly concentrated on the +1 or -1 order diffraction light, which greatly improves the utilization rate of light energy.

[0065] In practical applications, the phase plate is located in front of or behind the spatial light modulator, or the phase plate structure is directly prepared on one side of the spatial light modulator, thereby obtaining an integrated display device.

[0066] It should be pointed out that the embodiments described above are also applicable to color display applications. To this end, a three-color (or white) LED light bar can be used as a light source, and a color filter can be set in a wide-viewing angle three-dimensional display device. The color filter can be stacked with the phase plate and the spatial light modulator, and the stacking order can be variable. For example, the color filter can be arranged between the backlight plate and the spatial light modulator, between the spatial light modulator and the phase plate, or after the phase plate. Preferably, the color filter is arranged between the spatial light modulator and the phase plate. The light beam emitted from the backlight plate is provided with image information for multi-viewing angle naked-eye 3D display by the spatial light modulator, and then the wavelength information is loaded by the color filter, and finally the phase plate is used to realize phase modulation, thereby forming multiple converging light fields in the visible area in front of the phase plate to achieve the effect of naked-eye 3D display.

[0067] Compared with the prior art, the wide viewing angle three-dimensional display device of the present invention has many advantages. For example, it can provide a larger field of view so that clear naked-eye 3D or 2D images can be viewed without visual fatigue in any direction of the plane. For another example, since the diffraction optical element can eliminate the 0th order diffraction and concentrate the energy on the required diffraction order, the diffraction efficiency is significantly improved. For another example, the backlight plate (including LED light source, light guide plate and optical film) and Fresnel lens can be industrially produced using existing nanoimprint technology. The manufacturing process is mature, product consistency is easy to ensure and it is conducive to reducing costs. In addition,

[0068] Each unit of the backlight panel can be designed in a modular way, and each module realizes relatively independent optical characteristics (such as illumination uniformity, outgoing light divergence angle, etc.), which decouples various parameters, simplifies the design process and makes it easier to adjust the optical parameters. Furthermore, the wide viewing angle three-dimensional display device of the present invention is composed of a plurality of thin film optical devices stacked together, has good compatibility with the existing liquid crystal screen structure, and has a wide range of applications.

[0069] The above describes the principles and preferred embodiments of the present invention. However, the present invention should not be construed as being limited to the specific embodiments discussed. The preferred embodiments described above should be considered illustrative rather than restrictive, and it should be understood that those skilled in the art may make changes in these embodiments without departing from the scope of the present invention as defined in the following claims.

Claims

1. A three-dimensional display device with a large viewing angle, characterized in that: Include: a backlight panel configured to convert the light beam emitted by the light source into a first collimated light beam; a spatial light modulator located in the propagation direction of the first collimated light beam, configured to load multi-view mixed image information onto the first collimated light beam by amplitude modulation to form a second collimated light beam; as well as a phase plate located in the propagation direction of the second collimated light beam, which has a diffraction structure, and the diffraction structure is configured to project an image of each viewing angle in the image carried by the second collimated light beam to a corresponding set of observation positions, The spatial light modulator includes a first body pixel, each body pixel includes a plurality of sub-pixels, each sub-pixel corresponds to a different viewing angle, and the diffraction structure includes a plurality of micro-structure units, each micro-structure unit is configured to project a light beam from a sub-pixel corresponding to the same viewing angle in the plurality of body pixels of the spatial light modulator to a set of observation positions associated with the sub-pixel.

2. The device as claimed in claim 1, wherein the diffraction structure is implemented by one of the following structures: a one-dimensional nanograting, a two-dimensional nanograting, a spatially multiplexed nanograting, a nanograting array and a diffractive optical element.

3. The device as claimed in claim 2, wherein: The diffraction structure is realized by using a diffraction optical element, and the diffraction efficiency of the diffracted light at the zeroth order of diffraction is minimized by adjusting the structural depth of the diffraction optical element.

4. The device according to claim 1, wherein: The backlight panel comprises: A light guide plate, comprising a first microstructure located on an upper surface, a lower surface or an inner portion of the light guide plate, the first microstructure having periodically distributed first units, and the light beam emitted by the light source is scattered to the outside of the light guide plate through the first microstructure; and The optical film stacked with the light guide plate comprises a second microstructure located on the surface of the optical film, the second microstructure having periodically distributed second units, and the light beam scattered to the outside of the light guide plate by the first microstructure is transformed into the first collimated light beam by the second microstructure.

5. The device according to claim 4, wherein: The first unit is one of a microprism, a microlens, a free-form surface lens or a pit.

6. The device according to claim 4, wherein: The second unit is one of a micro lens, a Fresnel lens or a film lens.

7. The device of claim 4, wherein: The backlight panel further includes a light shielding plate, which includes a light shielding structure matching and corresponding to the first microstructure and the second microstructure to filter out stray light emitted from the second microstructure. 8 . The device of claim 7 , wherein the light shielding plate is disposed at one of the following positions: between the light guide plate and the optical film, inside the light guide plate, and inside the optical film.

9. The device of claim 4, wherein: The light source is integrated into the device and is located at the side of the backlight panel.

10. The device of claim 9, wherein: The light source is an LED linear array light source.

11. The device of claim 1, wherein: The spatial light modulator is a liquid crystal display unit.

12. The device of claim 1, wherein: The method further includes a light shielding plate located between the spatial light modulator and the phase plate.

13. The device according to claim 1, wherein: The light source is a white light source or a three-primary color light source, and the device further comprises a color filter stacked together with the spatial light modulator and the phase plate.

14. The device as claimed in claim 13, wherein: The color filter is arranged between the spatial light modulator and the phase plate.

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