Three-dimensional display device

Abstract

The present invention relates to display technologies, and particularly to a device for realizing multi-view display of autostereoscopic three-dimensional images. A three-dimensional display device according to one aspect of the present invention is characterized by comprising: a light source module configured to emit a first light beam; a spatial light modulator located in the propagation direction of the first light beam, configured to load multi-view mixed image information onto the first light beam by amplitude modulation to form a second light beam; and a phase plate located in the propagation direction of the second light beam, having a diffraction structure configured to project images of different views in the image carried by the second light beam to respective corresponding multiple viewing positions.

Description

Technical Field

[0001] The present invention relates to display technology, and particularly to a device for realizing multi-view display of naked-eye three-dimensional images. Background Art

[0002] With the improvement of living standards and the rapid development of science and technology, a realistic visual experience has become the pursuit of people for display screens, and 3D display technology has emerged as the times require. Not only in the traditional display industry, but also in many fields such as the multimedia field and software development, the development and application of 3D display technology are urgently needed. Traditional 3D display technology requires the use of additional auxiliary devices (such as 3D glasses, etc.) to observe stereoscopic images, which greatly limits the freedom of people to watch. Therefore, the development of naked-eye 3D display technology is an irresistible 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. Or rather, the image information is transmitted through the light field and converges at the observation point. Therefore, the entire image from different perspectives can be observed at different observation points in space without interference from each other. However, for decades, due to the limitations of holographic recording materials, information volume, and technical processes, holographic display has not been able to achieve wide-view dynamic color naked-eye 3D display.

[0004] Naked-eye 3D display technology based on the parallax principle includes the barrier method and the lenticular lens method. In these technologies, a barrier screen or a lenticular lens array is arranged on the surface of a liquid crystal display panel to achieve the separation of images from different perspectives in the spatial angle. Since it is difficult to eliminate ghost images and stray light, visual fatigue is easily caused when observing such 3D images. At the same time, affected by stray light, the viewing angle interval is usually set relatively large, resulting in discontinuous viewing angles and unable to achieve a seamless naked-eye 3D display effect. In addition, existing naked-eye 3D display devices are relatively large in size and difficult to be integrated into small devices such as mobile phones. Summary of the Invention

[0005] An object of the present invention is to provide a three-dimensional display device, which has the advantages of low manufacturing cost, simple design, and compact structure.

[0006] The three-dimensional display device according to one aspect of the present invention includes:

[0007] A light source module configured to emit a first light beam;

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

[0009] A phase plate located in the propagation direction of the second light beam, which has a diffraction structure configured to project images of different viewing angles in the image carried by the second light beam to respective corresponding multiple viewing positions.

[0010] Preferably, in the above device, the first light beam is a parallel light or a divergent light from a point light source.

[0011] Preferably, in the above device, the spatial light modulator includes a plurality of volume pixels, each volume pixel includes a plurality of sub-pixels, each sub-pixel corresponds to a different viewing angle, the diffraction structure includes a plurality of nanostructure units, and each nanostructure unit is configured to project the light beams from the sub-pixels corresponding to the same viewing angle in the plurality of volume pixels to the multiple viewing positions associated with the sub-pixel.

[0012] Preferably, in the above device, the diffraction structure is implemented by using one of the following structures: one-dimensional nanogratings, two-dimensional nanogratings, spatially multiplexed nanogratings, nanograting arrays, and diffractive optical elements.

[0013] Preferably, in the above device, the diffraction structure is implemented by using a diffractive optical element, and by adjusting the structural depth of the diffractive optical element, the diffraction efficiency of the diffracted light at the zero-order diffraction order is minimized.

[0014] Preferably, in the above device, the light source module includes:

[0015] A light source;

[0016] A backlight plate, which includes:

[0017] A light guide plate, the light source is located at the side of the light guide plate, the light guide plate includes a first microstructure located on the upper surface, lower surface or inside of the light guide plate, the first microstructure has periodically distributed first units, so that the light beam emitted by the light source is scattered to the outside of the light guide plate by the first microstructure; and

[0018] An optical film stacked with the light guide plate, which includes a second microstructure located on the surface of the optical film, the second microstructure has 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.

[0019] Preferably, in the above device, the first unit is one of a micro prism, a micro lens, a free-form surface lens or a pit.

[0020] Preferably, in the above device, the second unit is one of a micro lens, a Fresnel lens or a thin film lens.

[0021] Preferably, in the above-mentioned device, the backlight plate further includes a light-shielding plate, which includes a light-shielding structure that matches and corresponds to the first microstructure and the second microstructure to filter out stray light emitted from the second microstructure.

[0022] Preferably, in the above-mentioned device, one of the following positions: between the light guide plate and the optical film, inside the light guide plate, and inside the optical film.

[0023] Preferably, in the above-mentioned device, the light source is an LED line array light source.

[0024] Preferably, in the above-mentioned device, the spatial light modulator is a liquid crystal display unit.

[0025] Preferably, in the above-mentioned device, the light source is a white light source or a three-primary color light source, and the device further includes a color filter stacked together with the spatial light modulator and the phase plate.

[0026] Preferably, in the above-mentioned device, the color filter is disposed between the spatial light modulator and the phase plate. Description of the Drawings

[0027] Figure 1 Schematic diagram of a three-dimensional display device according to an embodiment of the present invention.

[0028] Figure 2 For application to Figure 1 Schematic diagram of the backlight plate of the device shown.

[0029] Figure 3 For another application to Figure 1 Schematic diagram of the backlight plate of the device shown.

[0030] Figures 4a - 4d For application to Figure 1 Schematic diagram of a single nanostructure unit of the phase plate in the embodiment shown.

[0031] Figures 5a - 5c For the phase plate sub-pixel viewpoint (array) effect composed of the Figures 4a - 4d nanostructure unit shown.

[0032] Figure 6 Schematic diagram showing a multi-view image display structure for expanding the longitudinal viewing angle.

[0033] Figure 7 Schematic diagram showing a multi-view image display structure for expanding the lateral viewing angle.

[0034] Figure 8 Schematic diagram showing another multi-view image display structure for expanding the lateral viewing angle.

[0035] Figure 9 Shown is a schematic diagram of a panoramic display structure achieved by simultaneously expanding the vertical and horizontal field of view angles.

[0036] Figure 10 Shown is another schematic diagram of a panoramic display structure achieved by simultaneously expanding the vertical and horizontal field of view angles. Detailed implementation manners

[0037] The object of the present invention will be described in detail below with reference to the accompanying drawings.

[0038] Figure 1 Shown is a schematic diagram of a three-dimensional display device according to an embodiment of the present invention.

[0039] Figure 1 The device 10 shown includes a light source module 110, a spatial light modulator 120, and a phase plate 130. Refer to Figure 1 , the spatial light modulator 120 is disposed in the propagation direction of the light beam B1 (hereinafter also referred to as the first light beam) emitted by the light source module 110, and it loads multi-view mixed image information onto the first light beam B1 through amplitude modulation to form a second light beam B2. The phase plate 130 is disposed in the propagation direction of the second light beam B2, and it projects the image of each view in the image carried by the second light beam B2 to their respective corresponding multiple viewing positions (for example, different viewing areas arranged around the curve (or surface) of the display desktop) by using nanostructure units, so as to obtain the effect of multi-view display with naked-eye 3D.

[0040] As will be seen below, by using the nanostructure units of the phase plate, the image of the same view can be converted to multiple viewpoints or a visual window composed of multiple viewpoint arrays, so as to expand the field of view angle to achieve the effect of panoramic display without increasing the display information throughput.

[0041] Figure 2 Shown is a schematic diagram of a light source module applicable to the device according to another embodiment of the present invention Figure 1 shown in

[0042] Figure 2 The light source module 110 shown includes a light source 111 and a backlight plate 112. The backlight plate 112 can be, for example, a directional backlight plate, which includes a light guide plate 1121 and an optical film 1122. Exemplarily, the optical film 1122 can be a micro-nano optical film. As Figure 2 shown, a first microstructure 1121A having periodically distributed first units (shown as pits in the figure) is formed on the upper surface of the light guide plate 1121. The light source 111 is located at the side of the light guide plate 1121, and the light beam emitted by it enters the light guide plate 1121 and is scattered to the outside of the light guide plate 1121 through the first microstructure 1121A.

[0043] Although Figure 2 the first microstructure 1121A shown in

[0043] is formed on the upper surface of the light guide plate 1121, it can also be formed on the lower surface or inside the light guide plate 1121. Preferably, the size of the first microstructure is between 100 nm and 1 mm. In Figure 2 the backlight panel 112 shown in Figure 2 , the first unit is exemplarily shown in the form of a pit, but it can also be other forms of optical elements, such as including but not limited to microprisms, microlenses, free-form lenses, etc.

[0044] Continuing to refer to Figure 2 , the optical film 1122 is located below the light guide plate 1121. The optical film 1122 can be stacked with the light guide plate 1121 or maintained with a certain air gap from the light guide plate 1121 (when the refractive index of the optical film is close to or higher than that of the light guide plate). In addition, a low refractive index layer can be inserted between the light guide plate 1121 and the optical film 1122 to avoid forming total reflection conditions in the light guide plate. As Figure 2 shown, a second microstructure 1122A with periodically distributed second units is formed on the surface of the optical film 1122. The second microstructure 1122A is structurally matched with the first microstructure 1121A, and its function is to transform the divergent light beam from the light guide plate 1121 into a first light beam B1 emitted along one or more directions. Preferably, the second microstructure 1122A adopts configurations such as a microlens array, a Fresnel lens array, a thin film lens array, a binary structured light array, etc. The lens units of the microlens array, Fresnel lens array or thin film lens array can be optimized according to the relative position with the microstructure in the light guide plate to obtain better collimation or focusing effects. For example, the diameter of each unit or microlens in the optical film 1122 can be designed to be larger than the size of the unit or pit structure of the light guide plate 1121.

[0045] 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 and 2.5. Preferably, plastic can be used to make the product lighter and reduce costs. In addition, the light guide plate 1121 can be composed of one material or composed of multiple materials with different refractive indices. The light guide plate and the optical film can be fabricated, for example, by using a gray-scale lithography process, a laser etching process, etc., and mass replication can be achieved by using a nanoimprint process.

[0046] Preferably, a light shielding plate can be provided in the backlight panel 112 to filter out unwanted stray light. For example, in Figure 3In the backlight panel shown, a light-shielding plate 1123 can be considered to be disposed between the light guide plate and the optical film. The light-shielding plate includes a light-shielding plate that matches and corresponds to the first microstructure 1121A and the second microstructure 1122A, so as to filter out stray light emitted from the second microstructure. The light-shielding plate can be a single-layer or multi-layer independent structure, and can 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 functional composite optical device.

[0047] It should be noted that in this specification, a collimated beam, a parallel light, a directional beam, and a converging beam propagating in one direction refer to the emitted light rays with a full width at half maximum of the divergence angle within 30°. Preferably, the full width at half maximum of the divergence angle of the emitted light rays is within 10°.

[0048] In Figure 1 In the embodiment shown, the spatial light modulator 120 is used for amplitude modulation, that is, loading image information mixed with multiple viewpoints. The spatial light modulator can include, for example, a display panel, a driving circuit, a control system, and software control. According to the needs of specific application fields, the spatial light modulator can achieve monochromatic or color display. Preferably, the spatial light modulator 120 can be a liquid crystal display unit. The spatial light modulator 120 can include a plurality of volume pixels or amplitude modulation pixels, each volume pixel includes a plurality of sub-pixels, and each sub-pixel corresponds to a different viewpoint.

[0049] 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 viewpoint or observation position, but as will be seen from the following description, in the present invention, the phase plate projects the image of each sub-pixel of the spatial light modulator to a corresponding viewpoint array or a set of observation positions, thereby broadening the viewing angle.

[0050] In order to obtain a set of observation positions, in this embodiment, the phase plate 130 has a diffraction structure, and the diffraction structure includes a plurality of volume pixels. Further, each volume pixel of the phase plate 130 includes a plurality of nanostructure units, and each nanostructure unit is matched and aligned with the viewpoint image pixel of the spatial light modulator, that is, the light beams of the sub-pixels corresponding to the same viewpoint in the plurality of volume pixels from the spatial light modulator 120 are projected to a set of observation positions associated with the sub-pixel. Preferably, the diffraction structure can be implemented by various structures, such as including but not limited to one-dimensional nanogratings, two-dimensional nanogratings, spatially multiplexed nanogratings, nanograting arrays, and diffractive optical elements (or secondary optical elements).

[0051] Figures 4a - 4d For application to Figure 1 Schematic diagram of a single nanostructure unit of the phase plate in the embodiment shown.

[0052] Taking Figure 4aFor example, the nanostructure unit 131 adopts the form of a pixel unit, which is divided into 9 grating regions 1a - 1i with different periods and / or orientation angles. When the light from a sub - pixel of the spatial light modulator 120 arrives, different grating regions will deflect the light to different viewing positions, thereby realizing the projection of a light beam from the same viewing angle to multiple viewing positions, thus expanding the field - of - view range.

[0053] The period and orientation angle of the grating region can be determined according to the following grating equations:

[0054] tanφ 1 = sinφ / (cosφ - nsinθ(Λ / λ)) (1)

[0055] sin 2 (θ 1 ) = (λ / Λ) 2 +(nsinθ) 2 - 2nsinθcosφ(λ / Λ) (2)

[0056] Among them, θ 1 and φ 1 respectively represent the diffraction angle of the diffracted light (the angle between the diffracted light ray and the negative z - axis direction) and the azimuth angle (the angle between the diffracted light ray and the positive y - axis direction), θ and λ respectively represent the incident angle of the light source (the angle between the incident light ray and the negative z - axis direction) and the wavelength, Λ and φ respectively represent the period and orientation angle of the nano - diffraction grating (the angle between the groove direction and the positive x - axis direction), and n represents the refractive index of the light wave in the medium.

[0057] Therefore, when the wavelength of the incident light ray, the incident angle, the diffraction angle of the diffracted light ray, and the diffraction azimuth angle are determined, the required grating period and orientation angle can be calculated using the above formula.

[0058] For another example, for another example, Figure 4b the nanostructure unit 131 shown adopts the form of grating spatial multiplexing, which is composed of 9 gratings stacked with different periods and / or orientation angles. When the light from a sub - pixel of the spatial light modulator 120 arrives, different gratings also deflect the light to different viewing positions, thereby realizing the projection of a light beam from the same viewing angle to multiple viewing positions, thus expanding the field - of - view range.

[0059] Figure 4c and 4d the nanostructure units shown are respectively a two - step diffractive optical element and a multi - step diffractive optical element, which can also deflect the light from one viewing angle to different viewing positions.

[0060] Figures 5a - 5c For Figures 4a - 4dSchematic diagram of the sub-pixel viewing point (array) effect of the phase plate composed of the shown nanostructure units. The light incident on a single nanostructure unit undergoes wavefront transformation to form multiple visible regions, and these visible regions can be, for example, as Figure 5a shown in the form of strips, as Figure 5b shown in the form of rings, or as Figure 5c shown in the form of crosses. Obviously, this expands the visible range in the horizontal and / or vertical directions, enabling the observer to observe the information image of the same viewing angle when moving up, down, left, or right.

[0061] In the present invention, the term "omnidirectional display" can be understood as a display implemented by simultaneously expanding the viewing angle in the horizontal and vertical directions. The following will be described separately from two aspects: expanding the horizontal viewing angle and expanding the vertical viewing angle.

[0062] Figure 6 Schematic diagram showing a multi-view image display structure for expanding the vertical viewing angle.

[0063] Without loss of generality, Figure 6 a display device with 4 viewing angles is taken as an example for illustration. In Figure 6 , each volume pixel on the phase plate 130 contains 4 sub-pixels or nanostructure units. Exemplarily, Figure 6 each nanostructure unit in Figure 6 contains 3 nano gratings. By controlling the orientation angle and / or period of the nano gratings, 3 visible regions can be formed longitudinally as shown in

[0064] Figure 7 . Each volume pixel on the phase plate 130 is matched and aligned with the volume pixel of the spatial light modulator 120, so that 3 information images of the same viewing angle can be presented in 3 visible regions arranged longitudinally, thereby achieving the effect of expanding the vertical viewing angle without increasing the refresh display information required by the spatial light modulator.

[0065] Similarly, Figure 7 a display device with 4 viewing angles is also taken as an example for illustration. In Figure 7 , each volume pixel on the phase plate 130 corresponds to a volume pixel of the spatial light modulator 120 and contains 4 nanostructure units. Each nanostructure unit is stacked by multiple nano grating structures (for example, as Figure 4bAs shown). By controlling the orientation angle and period of these spatially multiplexed nanostructured gratings, multiple visible regions can be formed transversely at regular intervals. Each volume pixel on the phase plate 130 is matched and aligned with the volume pixel of the spatial light modulator 120, whereby multiple information images of the same viewing angle can be presented within the visible regions arranged at regular intervals, thus achieving the effect of expanding the viewing angle without increasing the amount of refreshed display information required by the spatial light modulator.

[0066] Figure 8 FIG. shows a schematic diagram of another multi-view image display structure for expanding the horizontal viewing angle.

[0067] Similarly, Figure 8 a display device with four viewing angles is also taken as an example for illustration. In Figure 8 , each volume pixel on the phase plate 130 corresponds to a volume pixel of the spatial light modulator 120 and includes four nanostructure units (e.g., nanostructure units having the form shown in Figure 4c and 4d ). By designing the structure of the diffractive optical element according to the optical wave diffraction theory, multiple visible (strip-shaped) regions can be formed transversely at regular intervals. Each volume pixel on the phase plate 130 is matched and aligned with the volume pixel of the spatial light modulator 120, whereby multiple information images of the same viewing angle can be presented within the visible (strip-shaped) regions arranged at regular intervals. At the same time, the nanostructure units of different sub-pixels corresponding to the information images of different viewing angles are sequentially distributed in the horizontal direction, jointly forming a cyclically distributed visible point (line) array region 1-4, thus achieving the effect of expanding the viewing angle without increasing the amount of refreshed display information required by the spatial light modulator.

[0068] The diffraction efficiency η of a diffractive optical element or a binary optical element can be determined by the following formula:

[0069]

[0070] where N is the number of steps of the binary optical element and m is the diffraction order.

[0071] In a conventional diffraction grating, the zero-order diffracted light occupies most of the energy, while the useful +1 or -1 order diffracted light has 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 diffractive optical element on the phase plate, the diffraction efficiency at the diffraction order of m = 0 can be minimized (e.g., equal to 0), that is, the zero-order diffracted light is completely eliminated, so that the energy is mainly concentrated on the +1 or -1 order diffracted light, which greatly improves the light energy utilization rate.

[0072] Figure 9FIG. 0 shows a schematic diagram of a panoramic display structure achieved by simultaneously expanding the vertical and horizontal field of view angles. Without loss of generality, Figure 9 a panoramic display structure with 3 voxels is described. In Figure 9 , each voxel on the phase plate 130 includes 4 sub-pixels or nanostructure units. Exemplarily, Figure 6 each nanostructure unit in Figure 4a can adopt the form of a pixel unit as shown in Figure 4b , or adopt the form of grating spatial multiplexing as shown in Figure 4c and 4d , or also adopt the form of a diffractive optical element as shown in

[0073] Figure 10 FIG. 18 shows another schematic diagram of a panoramic display structure achieved by simultaneously expanding the vertical and horizontal field of view angles. Compared with the display structure shown in Figure 9 , the main difference lies in the arrangement of multiple visible regions of the image information of the same viewing angle in the vertical and horizontal directions.

[0074] It should be noted that the above-described embodiments can also be applied to color display applications. For this purpose, a three-color (or white) LED light bar can be used as the light source, and color filters are provided in the device for realizing the autostereoscopic 3D image display. The color filters can be stacked with the phase plate and the spatial light modulator, and the stacking order can be variable. For example, the color filters can be arranged between the backlight panel and the spatial light modulator, between the spatial light modulator and the phase plate, or behind the phase plate. Preferably, the color filters are arranged between the spatial light modulator and the phase plate. The light beam emitted from the backlight panel provides the image information for the autostereoscopic 3D display with multiple viewing angles by the spatial light modulator, then the wavelength information is loaded by the color filters, and finally the phase modulation is achieved by the phase plate, so as to form multiple converging light fields in the visible region in front of the phase plate to achieve the effect of autostereoscopic 3D display.

[0075] Compared with the prior art, the device for realizing naked-eye three-dimensional image display of the present invention has many advantages. For example, it can provide a large viewing angle, so that clear naked-eye 3D or 2D images can be viewed without visual fatigue in any direction on a plane. Another example is that since the diffractive optical element can eliminate the 0th-order diffraction and concentrate the energy on the required diffraction orders, the diffraction efficiency is significantly improved. Still another example is that the backlight panel (including the LED light source, the light guide plate, and the optical film) and the Fresnel lens can both be industrially produced by using the existing nanoimprinting technology, the manufacturing process is mature, the product consistency is easy to ensure, and it is beneficial to reduce costs. In addition, each unit of the backlight panel can be modularly designed, and each module realizes relatively independent optical characteristics (such as illumination uniformity, exit light divergence angle, etc.), which decouples the various parameters, simplifies the design process, and makes the adjustment of optical parameters easier. Furthermore, the device for realizing naked-eye three-dimensional image display of the present invention is composed of a stack of multiple thin-film optical devices, has good compatibility with the existing liquid crystal screen framework, and has a wide application field.

[0076] The principles and preferred embodiments of the present invention have been described above. However, the present invention should not be construed as being limited to the specific embodiments discussed. The above preferred embodiments should be considered illustrative rather than restrictive, and it should be understood that those skilled in the art can make changes in these embodiments without departing from the scope of the present invention defined by the following claims.

Claims

1. A three-dimensional display device, characterized in that, it comprises: a light source module configured to emit a first light beam; a spatial light modulator located in the propagation direction of the first light beam, configured to load multi-view mixed image information onto the first light beam by amplitude modulation to form a second light beam; and a phase plate located in the propagation direction of the second light beam, having a diffraction structure configured to project images of different views in the image carried by the second light beam to respective corresponding multiple viewing positions, wherein, the spatial light modulator comprises a plurality of volume pixels, each volume pixel comprises a plurality of sub-pixels, each sub-pixel corresponds to a different view, the diffraction structure comprises a plurality of nanostructure units, and each nanostructure unit is configured to project the light beams from the sub-pixels corresponding to the same view among the plurality of volume pixels to the multiple viewing positions associated with the sub-pixel.

2. The device according to claim 1, wherein, the first light beam is parallel light or point light source divergent light.

3. The device according to claim 1, wherein the diffraction structure is implemented by using one of the following structures: one-dimensional nanograting, two-dimensional nanograting, spatially multiplexed nanograting, nanograting array, and diffractive optical element.

4. The device according to claim 3, wherein, the diffraction structure is implemented by a diffractive optical element, and the diffraction efficiency of the diffracted light at the zero-order diffraction order is minimized by adjusting the structural depth of the diffractive optical element.

5. The device according to claim 1, wherein, the light source module includes: a light source; a backlight plate, which includes: a light guide plate, the light source is located at the side of the light guide plate, the light guide plate includes a first microstructure located on the upper surface, lower surface or inside of the light guide plate, the first microstructure has periodically distributed first units, so that the light beam emitted by the light source is scattered to the outside of the light guide plate by the first microstructure; and an optical film stacked with the light guide plate, which includes a second microstructure located on the surface of the optical film, the second microstructure has 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 light beam by the second microstructure.

6. The device according to claim 5, wherein, the first unit is one of a micro prism, a micro lens, a free-form surface lens or a pit.

7. The device according to claim 5, wherein, the second unit is one of a micro lens, a Fresnel lens or a thin film lens.

8. The device according to claim 5, wherein, the backlight plate further includes a light shielding plate, which includes a light shielding structure matching the first microstructure and the second microstructure to filter out stray light emitted from the second microstructure.

9. The device according to claim 8, wherein the light shielding plate is located 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.

10. The device according to claim 8, wherein, the light source is an LED line array light source.

11. The device according to claim 1, wherein, the spatial light modulator is a liquid crystal display unit.

12. 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 includes a color filter stacked together with the spatial light modulator and the phase plate.

13. The device according to claim 12, wherein, the color filter is disposed between the spatial light modulator and the phase plate.

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