Three-dimensional display device and related beam shaping structure

Abstract

A three-dimensional display device (1) comprising: a light source (2) having an array of pixel cells, each pixel cell in the array of pixel cells comprising a plurality of sub-pixels; the diaphragm unit array (3) comprises a plurality of diaphragm units, and the plurality of diaphragm units are in one-to-one correspondence with the plurality of sub-pixels in the plurality of pixel units and are used for limiting a divergence angle (gamma) of a light beam emitted from each sub-pixel; and the collimation deflection array (4) comprises a plurality of collimation deflection units, and the plurality of collimation deflection units are in one-to-one correspondence with the plurality of diaphragm units and are used for respectively collimating and deflecting the corresponding light beams limited by the divergence angle (gamma).

Description

Three-dimensional display device and related beam shaping structure Technical Field

[0001] The present disclosure relates to the field of three-dimensional display, and more particularly to a three-dimensional display device and a related beam shaping structure. Background Art

[0002] Compared with two-dimensional display technology, three-dimensional display technology can realistically reproduce the scenes of the objective world to a certain extent, making people feel immersive. Therefore, it has received more and more attention.

[0003] Based on different imaging principles, 3D display technologies are divided into two categories: the first category is non-naked-eye 3D display technology based on binocular parallax, but it requires special equipment (such as polarized glasses or a helmet) to see the 3D image, which reduces the enjoyment and naturalness of viewing. Long-term viewing can also lead to visual fatigue and reduced comfort. The second category is naked-eye 3D display technology, which requires light field manipulation to direct light from corresponding viewpoints to corresponding viewing areas. Due to the parallax of images from different viewpoints, a visual three-dimensional (3D) effect can be created.

[0004] Summary of the Invention

[0005] The present disclosure aims to provide an improved three-dimensional display device and a related beam shaping structure.

[0006] According to a first aspect of the present disclosure, a three-dimensional display device is provided. The three-dimensional display device includes: a light source; a pixel unit array having a plurality of pixel units, each of the plurality of pixel units including a plurality of sub-pixels; an aperture unit array including a plurality of aperture units, each of the plurality of aperture units corresponding one-to-one with the plurality of sub-pixels in the plurality of pixel units, for limiting the divergence angle of a light beam emitted from each sub-pixel; and a collimating and deflecting array including a plurality of collimating and deflecting units, each of the plurality of collimating and deflecting units corresponding one-to-one with the plurality of aperture units, for collimating and deflecting the light beams limited by the aperture unit array.

[0007] It will be understood that, with the three-dimensional display device of the present disclosure, the combination of the aperture unit and the collimating deflecting unit of the present disclosure will be relatively light and thin compared to the traditional solution using a collimating backlight structure.

[0008] In some embodiments, each collimating and deflecting unit is a metasurface comprising multiple micro-nanostructure units formed on a substrate. In these embodiments, the combination of the aperture unit and the collimating and deflecting unit disclosed herein is further lightweight and thin. Furthermore, the use of a metasurface allows for more flexible control of the viewpoint's deflection direction, resulting in greater freedom in viewpoint design. Furthermore, the resulting beam divergence angle is small, collimation performance is excellent, and crosstalk between viewpoints is minimized, effectively enhancing 3D display quality.

[0009] In some embodiments, each micro-nanostructure unit comprises a nano-pillar structure.

[0010] In some embodiments, the orthographic projection of the nanorod structure on the substrate is a C4 rotationally symmetric figure. With this nanorod structure, the calculation of the phase distribution of the metasurface can be more easily achieved.

[0011] In some embodiments, the spacing between the plurality of micro-nanostructure units is constant and less than 400 nm. With such spacing requirement, it can be helpful to design a metasurface for visible light wavelengths.

[0012] In some embodiments, when the nanopillar structure is a nanocylindrical structure, the diameter of the nanocylindrical structure is selected from the range of 50 nm to 400 nm. This size requirement not only takes into account the requirements of metasurface design for visible light wavelengths, but also makes nanofabrication easier to implement.

[0013] In some embodiments, the plurality of sub-pixels include blue sub-pixels, red sub-pixels, and green sub-pixels. In these embodiments, the three-dimensional display device of the present disclosure can achieve color three-dimensional display.

[0014] In some embodiments, the collimating and deflecting array is designed to collimate and deflect light emitted by the multiple sub-pixels in each pixel unit to different directions, wherein the different directions correspond to different viewpoints of the three-dimensional display device.

[0015] In some embodiments, the materials used to prepare the micro-nano structural units include titanium oxide and silicon nitride.

[0016] In some embodiments, the height of each aperture element is designed so that the angle of light emitted from the center of each sub-pixel along the highest point of the corresponding aperture element is no greater than 20°. This angle limit can reduce the design requirements for collimation of collimating and deflecting elements such as metasurfaces.

[0017] In some embodiments, the aperture unit array is made of a material having light absorption properties.

[0018] In some embodiments, the material having light absorbing properties is photoresist.

[0019] In some embodiments, the light source is selected from micro light emitting diodes, liquid crystal displays, or organic light emitting diodes.

[0020] According to a second aspect of the present disclosure, a beam shaping structure is provided. The beam shaping structure includes: a pixel-level light source; an aperture unit disposed above the pixel-level light source and configured to limit the divergence angle of a light beam emitted from the pixel-level light source; and a deflection unit disposed above the aperture unit and configured to deflect the light beam limited by the aperture unit.

[0021] It will be appreciated that the beam shaping structure disclosed herein provides an alternative beam shaping solution. This beam shaping structure also has the advantage of being lightweight and thin. In particular, when the deflection unit is a metasurface, this beam shaping structure can also more freely control the deflection direction.

[0022] According to a third aspect of the present disclosure, an optical device is provided. The optical device includes the beam shaping structure described in the second aspect. In some embodiments, the optical device is a three-dimensional display device.

[0023] According to a fourth aspect of the present disclosure, a method for preparing a three-dimensional display device is provided. The method includes: providing a light source having a pixel unit array, the pixel unit array including a plurality of pixel units, each pixel unit including a plurality of sub-pixels; arranging an aperture unit array above the pixel unit array, the aperture unit array including a plurality of aperture units, the plurality of aperture units corresponding one-to-one with a plurality of sub-pixels in the plurality of pixel units, for limiting the divergence angle of a light beam emitted from each sub-pixel; and arranging a collimating and deflecting array above the aperture unit array, the collimating and deflecting array including a plurality of collimating and deflecting units, the plurality of collimating and deflecting units corresponding one-to-one with the plurality of aperture units, for respectively collimating and deflecting the light beams limited by the aperture unit array.

[0024] According to a fifth aspect of the present disclosure, a method for fabricating a beam shaping structure is provided. The method comprises: providing a pixel-level light source; arranging an aperture unit above the pixel-level light source to limit the divergence angle of a light beam emitted from the pixel-level light source; and arranging a deflection unit above the aperture unit to deflect the direction of the light beam with the divergence angle limited.

[0025] It should be understood that the contents described in the Summary of the Invention section are not intended to limit the key or important features of the embodiments of the present disclosure, nor are they intended to limit the scope of the present disclosure. Other features of the present disclosure will become readily understood through the following description. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] The above and other features, advantages and aspects of the embodiments of the present disclosure will become more apparent with reference to the following detailed description in conjunction with the accompanying drawings. In the accompanying drawings, the same or similar reference numerals represent the same or similar elements, wherein:

[0027] FIG1 is a schematic diagram showing the principle of a conventional naked-eye 3D display solution;

[0028] FIG2 shows a schematic diagram of the principle of another conventional naked-eye 3D display solution;

[0029] FIG3 shows a schematic diagram of a partial structure of a three-dimensional display device according to an exemplary embodiment of the present disclosure;

[0030] FIG4 shows an exemplary arrangement of a light source having a pixel unit array according to an example embodiment of the present disclosure;

[0031] FIG5 shows a geometric diagram of parameters related to the phase distribution of a metasurface according to an example embodiment of the present disclosure;

[0032] FIG6 is a schematic diagram showing structural parameters of a nano-cylindrical structure with a substrate as a micro-nano structure unit according to an example embodiment of the present disclosure;

[0033] FIG7 is a schematic diagram showing the diameter distribution of nano-cylinder structures within 10×10 micro-nano structure units near the center point of a metasurface for a blue sub-pixel according to an exemplary embodiment of the present disclosure;

[0034] FIG8 is a schematic diagram showing the diameter distribution of nano-cylinder structures within 10×10 micro-nano structure units near the center point of a metasurface for a green sub-pixel according to an exemplary embodiment of the present disclosure;

[0035] FIG9 is a schematic diagram showing the diameter distribution of nano-cylinder structures within 10×10 micro-nano structure units near the center point of a metasurface for a red sub-pixel according to an exemplary embodiment of the present disclosure;

[0036] FIG10 shows a flowchart of a method for preparing a three-dimensional display device according to an example embodiment of the present disclosure; and

[0037] FIG11 shows a flow chart of a method for preparing a beam shaping structure according to an example embodiment of the present disclosure. DETAILED DESCRIPTION

[0038] The following describes embodiments of the present disclosure in more detail with reference to the accompanying drawings. Although certain embodiments of the present disclosure are shown in the accompanying drawings, it should be understood that the present disclosure can be implemented in various forms and should not be construed as limited to the embodiments described herein. Rather, these embodiments are provided to provide a more thorough and complete understanding of the present disclosure. It should be understood that the drawings and embodiments of the present disclosure are for illustrative purposes only and are not intended to limit the scope of protection of the present disclosure.

[0039] As mentioned above, the field of three-dimensional display has attracted more and more attention. In particular, for naked-eye three-dimensional display, there are various naked-eye three-dimensional display solutions.

[0040] In one example, Figure 1 shows a schematic diagram of the principles of a glasses-free 3D display solution. As shown in Figure 1, light from different sub-pixels of an LCD can be converged to a single point in space via a metagrating, acting as a deflection element. This can form multiple viewpoints, such as viewpoint 1 to viewpoint N. These images from different viewpoints can then form parallax, creating a visual 3D effect.

[0041] In one example, FIG2 shows a schematic diagram of the principle of another conventional naked-eye 3D display solution. As shown in FIG2 , a deflection element such as a lens is used to bend the light emitted by sub-pixels at different positions to different angles. By designing the light splitting law of the deflection element, the light of sub-pixels with the same viewpoint information can be converged at one point in space, thereby forming multiple viewpoints in a similar manner. In addition, there is also a 3D display solution that achieves the same light splitting principle as a lens by means of a parallax barrier.

[0042] Based on the basic principles of three-dimensional display, it can be understood that a collimated light beam with directional deflection can form a 3D display effect with low crosstalk and large depth of field. Therefore, the most important part of three-dimensional display design is the need to collimate and deflect the light.

[0043] However, the inventors noticed that most naked-eye three-dimensional display devices based on pixelated control use a combination of collimated backlight and deflection elements. Their collimated backlight systems are usually relatively thick, which will increase the thickness of flat-panel display devices such as mobile phones and computers as three-dimensional display devices, making them less portable and integrated.

[0044] The present disclosure aims to provide a lightweight design that achieves collimated deflection of light beams, thereby realizing a high-quality naked-eye 3D display effect, while avoiding the use of a traditional backlight structure. To achieve this goal, the present disclosure utilizes a combination of an aperture unit and a collimating and deflecting unit to achieve the collimated deflection of the light beams. The aperture unit is used to limit the divergence angle of the light beams from the sub-pixels of the light source, and the collimating and deflecting unit is used to deflect the light beams limited by the aperture unit, thereby achieving a 3D display effect. In particular, the collimating and deflecting unit of the present disclosure can be a metasurface.

[0045] As is known in the art, a metasurface is an artificial material smaller than the operating wavelength that enables flexible and effective manipulation of electromagnetic wave characteristics, including polarization, amplitude, phase, polarization mode, and propagation mode. Generally, light beam shaping can be achieved by manipulating the phase distribution of the metasurface.

[0046] It will be appreciated that, compared to conventional solutions using a collimated backlight structure, the combination of the aperture unit and collimating deflection unit disclosed herein is relatively lightweight and thin. In particular, when a metasurface is used as the collimating deflection unit, the combination of the aperture unit and collimating deflection unit disclosed herein is even lighter and thinner. Furthermore, compared to conventional solutions using traditional lenses as the collimating deflection unit, the use of a metasurface allows for more flexible control of the viewpoint's deflection direction, resulting in greater freedom in viewpoint design. The resulting light beam has a smaller divergence angle, better collimation performance, and less crosstalk between viewpoints, effectively enhancing the 3D display effect. Furthermore, the combination of the metasurface and aperture unit can also result in a relatively small viewpoint spread for light emitted from the same sub-pixel width at a given viewing distance, resulting in less crosstalk and a relatively large depth of field. Furthermore, compared to the use of traditional lenses, which can create repeated viewing zones in space, transition zones where the view zones switch, and the so-called reverse viewing phenomenon, the combination of the metasurface and aperture unit can also avoid the aforementioned drawbacks.

[0047] 3 , a partial structural diagram of a three-dimensional display device according to an exemplary embodiment of the present disclosure will be described below.

[0048] It should be understood that the three-dimensional display device of the present disclosure is a naked-eye three-dimensional display device, which can be any suitable type of display, including but not limited to mobile phones, tablet computers, desktop computers and personal digital assistants (PDAs).

[0049] As shown in FIG3 , the three-dimensional display device 1 of the present disclosure may include a light source 2 , an aperture unit array 3 , and a collimating deflection array 4 .

[0050] The light source 2 is used to provide image information, and may be, for example, a micro light emitting diode (micro-LED), a liquid crystal display (LCD), or an organic light emitting diode (OLED).

[0051] It should be understood that to achieve pixelated control of three-dimensional display, the light source 2 can be designed to have a pixel unit array, wherein the pixel unit array includes multiple pixel units, each of which can include multiple sub-pixels, such as multiple groups of three sub-pixels in an alternating arrangement of red, green, and blue (RGB). Furthermore, the light source 2 can provide image information for three-dimensional display by having the above-mentioned pixel unit array.

[0052] FIG4 shows an exemplary arrangement of a light source having an array of pixel units according to an exemplary embodiment of the present disclosure. For example only, as shown in FIG4 , each pixel unit may include, for example, 45 sub-pixels, which may be composed of, for example, 15 pixels, each of which includes three sub-pixels in an alternating arrangement of red, green, and blue (RGB) colors.

[0053] It should be noted that the term "pixel unit" in this disclosure can be defined as a combination of multiple sub-pixels, which can be composed of one pixel or multiple pixels. For example, when each pixel is typically composed of three sub-pixels of red, green, and blue (RGB) in an alternating arrangement, each pixel unit can include one or more such pixels. Furthermore, although the composition of each pixel is described using three RGB sub-pixels as an example, this is not limiting. Each pixel can also include more or fewer sub-pixels, or even only one sub-pixel (Note: in this case, the pixel can be understood as a special sub-pixel). Furthermore, the above-mentioned pixel unit or pixel does not necessarily consist of colored sub-pixels; it is also possible for it to consist of multiple sub-pixels of the same color. Furthermore, the arrangement of the alternating red, green, and blue (RGB) sub-pixels in Figure 4 is merely an example. In other embodiments, there may be other arrangements of sub-pixels that are completely different from the alternating red, green, and blue (RGB) sub-pixels shown in Figure 4. It should be understood that when the above-mentioned pixel unit includes sub-pixels of different colors, the 3D display device can form a color 3D display, while when the above-mentioned pixel unit includes sub-pixels of the same color, the 3D display device will present a monochrome 3D display.

[0054] It should also be understood that the number of sub-pixels included in each pixel unit is designed based on the number of viewpoints the 3D display device is intended to generate. Therefore, the greater the number of viewpoints designed for the 3D display device, the greater the number of sub-pixels in each pixel unit. Furthermore, based on the principle of generating viewpoints for 3D display, the number and position of sub-pixels in different pixel units should correspond to each other, and the light emitted by corresponding sub-pixels in different pixel units should converge to the same point in space at a predetermined distance, thereby generating multiple viewpoints in space corresponding to the number of sub-pixels.

[0055] For example, the sub-pixels in each pixel unit in FIG. 4 can be numbered from 1 to 45, where the 1st, 4th, 7th, 10th, ... correspond to red sub-pixels, the 2nd, 5th, 8th, 11th, ... correspond to green sub-pixels, and the 3rd, 6th, 9th, 12th, ... correspond to blue sub-pixels. The 1st, 2nd, and 3rd sub-pixels can be sub-pixels in the 1st pixel, and the 4th, 5th, and 6th sub-pixels can be sub-pixels in the 2nd pixel, etc. In this case, light emitted by correspondingly numbered sub-pixels in different pixel units (e.g., the 1st sub-pixel in the 1st pixel unit and the 1st sub-pixel in the Mth pixel unit) will be converged to the same point in space, thereby generating a number of viewpoints corresponding to the number of sub-pixels in each pixel unit, e.g., 45 viewpoints.

[0056] When the user's naked eyes perceive at least some of the multiple viewpoints, the user can perceive a 3D display effect due to parallax between the images received at different viewpoints. It is also understood that in the design of an actual 3D device, the deflection direction of light emitted by the sub-pixels contained in each pixel unit can be designed based on the spatial location of the desired viewpoints.

[0057] The function of the aperture unit array 3 is to limit the divergence angle of the light beam emitted from each sub-pixel. To this end, according to the design of the present disclosure, the aperture unit array 3 is arranged above the above-mentioned pixel unit array and may include a plurality of aperture units. Furthermore, the plurality of aperture units are arranged to correspond one-to-one with the above-mentioned plurality of sub-pixels to achieve the limitation of the divergence angle of the light beam emitted from each sub-pixel. It should be noted here that, as is well known in the art, an aperture refers to an entity that plays a limiting role on light in an optical system, and the "aperture unit" of this application can be defined as an aperture structure that limits the light generated by a light source (including a pixel-level light source such as a pixel or sub-pixel). For example, in Figure 3, for 3 sub-pixels, there are correspondingly 3 aperture units, and adjacent aperture units (or aperture structures) may share a boundary. It is easy to understand that aperture units that do not share a boundary are also possible.

[0058] To avoid crosstalk between light beams emitted from different sub-pixels (particularly adjacent sub-pixels), in some embodiments, the aperture element array 3 is constructed from a light-absorbing material. By way of example only, this light-absorbing material may include a photoresist having light-absorbing properties. In yet other embodiments, it is also possible for the aperture element array 3 to be constructed from a reflective material.

[0059] In some embodiments, the height of each aperture unit can be designed so that the angle γ at which light emitted from the center point of each sub-pixel exits along the highest point of the corresponding aperture unit is no greater than a predetermined value, for example, no greater than 20°, 15°, or 10 degrees. The term "highest point" should be defined as the highest point of the aperture unit visible from the perspective of the center point of the corresponding sub-pixel. Figure 3 shows an example of the angle γ. In this way, strict constraints can be placed on the divergence angle of the light beam emitted from each aperture unit. It should be understood that point light sources such as LEDs are typically Lambertian light sources, emitting light with a Lambertian distribution. The predetermined constraints on the divergence angle imposed by the aperture units described above can relax the requirements for the light beam emitted by the light source, and subsequently, combined with a collimating deflection unit, it can make it possible to eliminate the traditional collimating backlight system.

[0060] The function of the collimating and deflecting array 4 is to collimate and deflect the light beams with a predetermined divergence angle (for example, an emission angle of no more than 20°, 15°, or 10°) emitted from each aperture unit in the aperture unit array 3 to a predetermined direction in space. Specifically, according to the design of the present disclosure, the collimating and deflecting array 4 can be arranged above the aperture unit array 3 and include multiple collimating and deflecting units, wherein the multiple collimating and deflecting units can correspond one-to-one with the multiple aperture units, thereby respectively collimating and deflecting the corresponding light beams with limited divergence angles to predetermined directions. For example, as shown in Figure 3, the divergence-angle-limited light beams emitted by different sub-pixels in each pixel can be collimated and deflected to different predetermined directions in space.

[0061] In some embodiments, the collimating deflection array 4 can be, for example, a microlens or a grating structure. However, in particular, each collimating deflection unit in the collimating deflection array 4 of the present disclosure can be a metasurface, which includes multiple micro-nanostructure units formed on a substrate. As an example, the substrate can be formed of a transparent material such as glass, while the metasurface can be made of a material suitable for preparing metasurfaces, such as titanium oxide and silicon nitride.

[0062] In some embodiments, each of the plurality of micro-nanostructure units may include a nanocolumn structure, and the nanocolumn structure may include but is not limited to a regular column structure such as a nanocylindrical structure or a nanosquare column structure. In some embodiments, the orthographic projection of the nanocolumn structure on the substrate may be a C4 rotationally symmetric figure. Here, the so-called "C4 rotationally symmetric figure" means that its orthographic projection can coincide with the original figure when rotated 90 degrees around the center point. Obviously, the orthographic projection of the nanocylindrical structure or the nanosquare column structure on the substrate is a typical example of a C4 rotationally symmetric figure.

[0063] In order to more clearly understand how the metasurface as a collimating deflection unit is designed, the following will take the nanocylindrical structure as an example to describe how to design the nanocylindrical structure to prepare the metasurface.

[0064] First, it should be understood that the ability of a metasurface to collimate and deflect a light beam depends on its own phase distribution. As mentioned above, a metasurface can be formed from multiple micro-nanostructure units, so the metasurface's phase distribution will vary with the structural parameters of the micro-nanostructure units at different locations.

[0065] It is understood that since each sub-pixel is located at a specific position, the phase distribution of each metasurface corresponding to each sub-pixel is also a specific distribution. In some embodiments, the phase distribution of each metasurface can be expressed as follows.

[0066]

[0067] in The phase change provided for any point on the metasurface corresponding to each subpixel; x, y are the coordinate values ​​of the centers of the micro-nanostructure units at different positions with the center point of each metasurface as the origin; the x-axis and y-axis are defined as being parallel to the horizontal and vertical directions of the screen of the three-dimensional display device, respectively, and the z-axis is defined as being perpendicular to the screen; λ is the central wavelength of the light beam emitted by the subpixel, f is the height of the aperture unit, θ is the deflection angle of the light emitted from the metasurface, and α is the angle required for the projection of the deflected light through the origin on the metasurface plane to rotate clockwise to coincide with the x-axis. For greater clarity, FIG5 shows a geometric diagram of the parameters related to the phase distribution of the above-mentioned metasurface according to an example embodiment of the present disclosure.

[0068] As an example only, in the example where the micro-nano structure unit is a nano-cylindrical structure, the structural parameters of the nano-cylindrical structure can be described, for example, by a spacing (or period) P, a height H, and a diameter D, where the spacing P can be defined as the distance between the cylindrical center lines of two adjacent nano-cylindrical structures. In some embodiments, the spacing P between the micro-nano structure units can be constant, that is, the micro-nano structure units can be arranged periodically. Figure 6 shows a schematic diagram of the structural parameters of the nano-cylindrical structure unit with a substrate according to an example embodiment of the present disclosure. Note: For the sake of convenience of description, the periodic arrangement of the micro-nano structure units is taken as an example. At this time, the substrate of the metasurface can be divided into multiple squares, and each nano-cylindrical structure can correspondingly have a square substrate; in this case, the spacing P of the above-mentioned nano-cylindrical structure can be described instead by the side length of the above-mentioned square substrate.

[0069] In some embodiments, the spacing of the micro-nanostructure units may be selected to be no greater than 400 nm, for example, smaller than the wavelength of the targeted visible light (eg, red light, green light, or blue light), such as 350 nm, 300 nm, 250 nm, 200 nm, etc.

[0070] As a non-limiting example of the size design of the nanocylinder structure, the diameter D can be selected as a variable, and other parameters (such as spacing P and height H) can be selected as fixed quantities to simulate the phase and diameter structure library of the nanocylinder structure. Then, based on the phase corresponding to the specific position of each metasurface represented by the above formula (1) (which can be represented by the xy coordinates), the corresponding nanocylinder diameter can be selected in the structure library. In general, in order to facilitate the selection of a suitable nanocylinder diameter in the structure library, it is usually necessary to simulate so that the phase change range corresponding to the nanocylinder diameter can cover 0 to 2π. As an example, for visible light wavelengths, the diameter size of the nanocylinder structure can be selected, for example, from the range of 50nm to 400nm.

[0071] For example, for a blue sub-pixel with a single sub-pixel size of 6.4×6.4μm and a wavelength of 451nm, it can be assumed that the corresponding metasurface size is 6×6μm, the deflection angle θ is 10°, α is 0°, the aperture unit height f=17.17μm, and the parameters of the nano-cylinder structure are H=600nm and the spacing P=250nm. Then, the corresponding phase and diameter structure library can be obtained through simulation. Then, based on the phase distribution calculated by the above formula (1), the corresponding nano-cylinder diameter range can be obtained from the structure library, which can be, for example, 100-164nm. That is, for the spacing P=250nm, within the 6×6μm metasurface range, the diameter of each nano-cylinder within the range of 250×250nm will vary between 100-164nm. As an example only, Figure 7 shows a schematic diagram of the diameter distribution of the nano-cylinder structure within 10×10 micro-nano structure units near the center point of the metasurface for the blue sub-pixel according to an exemplary embodiment of the present disclosure.

[0072] For another example, for a green sub-pixel with a single sub-pixel size of 6.4×6.4μm and a wavelength of 526nm, it can be assumed that the corresponding metasurface size is 6×6μm, the deflection angle θ is 10°, α is 0°, the aperture unit height f=17.17μm, and the parameters of the nano-cylinder structure are H=600nm and P=300nm. Then, the corresponding phase and diameter structure library can be obtained through simulation. Then, based on the phase distribution calculated by the above formula (1), the corresponding nano-cylinder diameter range is obtained from the structure library, which can be, for example, 100-246nm. That is, for the spacing P=300nm, within the 6×6μm metasurface range, the diameter of each nano-cylinder within the 300×300nm range will vary between 100-246nm. As an example only, Figure 8 shows a schematic diagram of the diameter distribution of the nano-cylinder structure within 10×10 micro-nano structure units near the center point of the metasurface for the green sub-pixel according to an exemplary embodiment of the present disclosure.

[0073] For another example, for a red sub-pixel with a single sub-pixel size of 6.4×6.4μm and a wavelength of 633nm, it can be assumed that the corresponding metasurface size is 6×6μm, the deflection angle θ is 10°, α is 0°, the aperture unit height f=17.17μm, and the parameters of the nano-cylinder structure are H=600nm and P=350nm. Then, the corresponding structure library can be obtained through simulation. Then, based on the phase distribution calculated by the above formula (1), the corresponding nano-cylinder diameter range can be obtained from the structure library, which can be, for example, 100-320nm. That is, for the spacing P=350nm, within the 6×6μm metasurface range, the diameter of each nano-cylinder within the 350×350nm range will vary between 100-320nm. As an example only, Figure 9 shows a schematic diagram of the diameter distribution of the nano-cylinder structure within 10×10 micro-nano structure units near the center point of the metasurface for the red sub-pixel according to an exemplary embodiment of the present disclosure.

[0074] Although the design concept of the metasurface is described above using a nano-cylinder structure as an example, it should be understood that metasurfaces with other types of nano-cylinder structures can be designed in a similar manner. However, compared with other types of nano-cylinder structures, metasurfaces with nano-cylinder structures may be more advantageous because nano-cylinder structures are non-polarization responsive and their size design is simpler.

[0075] The application of the combination of the collimating deflection unit and the aperture unit in a three-dimensional display device has been described in detail above. It can be understood that this combination can make the three-dimensional display device unnecessary to use a traditional collimating backlight structure, thereby being lighter and thinner. In particular, in the embodiment where the collimating deflection unit is composed of a metasurface, the above combination can also make the thickness of the three-dimensional display device even thinner and lighter, and provide greater freedom in viewpoint design (which helps to more flexibly control the viewpoint density and viewpoint range), less crosstalk, and a greater depth of field, thereby improving the 3D display effect. In addition, the combination of the metasurface and the aperture unit can also eliminate the jump in the viewing area caused by the traditional use of lenses as deflection elements, thereby having an anti-peeping effect and avoiding the so-called reverse viewing phenomenon.

[0076] It should also be understood that the present disclosure is not limited to the application of the above-mentioned combination of a collimating and deflecting unit and an aperture unit in a 3D display device. In other embodiments, a deflecting unit (which may include a collimating and deflecting unit) and an aperture unit may be provided as part of a beam shaping structure. In this case, the beam shaping structure may be part of an optical device, which may include, but is not limited to, a 3D display device.

[0077] For example, in this embodiment, the beam shaping structure may include: a pixel-level light source; an aperture unit, disposed above the pixel-level light source, for limiting the divergence angle of the light beam emitted from the pixel-level light source; and a collimating and deflecting unit, disposed above the aperture unit, for collimating and deflecting the light beam limited by the aperture unit. In particular, in some embodiments where beam collimation is not required, the beam shaping structure may further include: a pixel-level light source; an aperture unit, disposed above the pixel-level light source, for limiting the divergence angle of the light beam emitted from the pixel-level light source; and a deflecting unit, disposed above the aperture unit, for deflecting the light beam with limited divergence angle.

[0078] It is understood that both the collimating and deflecting units described above can be further configured as metasurfaces, as metasurfaces can perform at least one of the functions of collimation and deflection. Note that the term "pixel-level light source" should be understood as a light source of pixel size or magnitude, including but not limited to pixels or sub-pixels derived from an image source.

[0079] It should also be understood that the aperture unit and collimating and deflecting unit of the aforementioned beam shaping structure are identical to the aperture unit in the aperture unit array and the collimating and deflecting unit in the collimating and deflecting array described above for the 3D display device, respectively. Therefore, the specific implementation of the aperture unit and collimating and deflecting unit in the aforementioned beam shaping structure, as well as the advantages or technical effects of their combination, can be referenced to the description of the 3D display device described above. The deflecting unit can be designed adaptively with reference to the collimating and deflecting unit, and therefore will not be further described here.

[0080] A flowchart of a method for preparing the above-mentioned three-dimensional display device according to the present disclosure will be briefly described below with reference to FIG. 10 .

[0081] As shown in FIG. 10 , the method may include: at block 1010 , providing a light source having a pixel unit array, wherein the pixel unit array includes a plurality of pixel units, and each pixel unit includes a plurality of sub-pixels.

[0082] As examples, the light source may include, but is not limited to, a micro light emitting diode (micro-LED), a liquid crystal display (LCD), or an organic light emitting diode (OLED).

[0083] In some embodiments, the multiple sub-pixels in each pixel unit may include a blue sub-pixel, a red sub-pixel, and a green sub-pixel. In some further embodiments, the multiple sub-pixels in each pixel unit may include monochrome pixels, thereby providing a monochrome three-dimensional display effect.

[0084] In box 1020, an aperture unit array is arranged above the pixel unit array, and the aperture unit array includes multiple aperture units, and the multiple aperture units correspond one-to-one to multiple sub-pixels in the multiple pixel units to limit the divergence angle of the light beam emitted from each sub-pixel.

[0085] In some embodiments, the aperture unit array can be made of a material with light-absorbing properties. However, this is not a limitation; in other embodiments, the aperture unit array can also be made of a reflective material. For example, the aperture unit array can be made of a light-absorbing photoresist. For example, the aperture unit array can be formed above the pixel unit array by etching.

[0086] To facilitate collimation and deflection by the downstream collimating and deflecting unit, in some embodiments, the height of each aperture unit can be designed so that the angle at which a light ray emitted from the center point of each sub-pixel exits along the highest point of the corresponding aperture unit is no greater than a predetermined value, such as no greater than 20°, 15°, or 10°. In this way, a strict constraint can be placed on the divergence angle of the light beam emitted from each aperture unit.

[0087] At block 1030, a collimating and deflecting array is disposed above the aperture element array. The collimating and deflecting array includes a plurality of collimating and deflecting units, each corresponding one to the plurality of aperture elements, for collimating and deflecting a corresponding light beam having a limited divergence angle. In particular, each collimating and deflecting unit can be a metasurface comprising a plurality of micro-nanostructure units formed on a substrate.

[0088] In an embodiment where each collimating and deflecting unit is a metasurface, each of the plurality of micro-nanostructure units comprises a nanopillar structure. Specifically, the orthographic projection of the nanopillar structure on the substrate can be a C4 rotationally symmetric pattern. More specifically, the nanopillar structure can include a nanocircular nanopillar structure and a nanosquare nanopillar structure.

[0089] In some embodiments, the spacing between the above-mentioned multiple micro-nanostructure units is constant and can be selected to be less than 400 nm, for example, less than the wavelength of the targeted visible light (for example, red light, green light or blue light), for example, 350 nm, 300 nm, 250 nm, 200 nm, etc.

[0090] In the embodiment where the nano-column structural unit is a nano-cylindrical structure, the diameter of the nano-cylindrical structure can be selected from the range of 50 nm to 400 nm.

[0091] A flow chart of a method for preparing the above-mentioned beam shaping structure according to the present disclosure will be briefly described below with reference to FIG. 11 .

[0092] As shown in FIG11 , at block 1110, a pixel-level light source is provided. It should be understood that the term "pixel-level light source" refers to a light source of pixel size or magnitude, including but not limited to pixels or sub-pixels derived from an image source. It should also be understood that in embodiments of the beam shaping structure, the pixel-level light source does not necessarily provide information about the image.

[0093] In block 1120 , an aperture unit is disposed above the pixel-level light source to limit a divergence angle of a light beam emitted from the pixel-level light source.

[0094] Similarly, the aperture unit can be made of a light-absorbing material. However, this is not a limitation; in other embodiments, the aperture unit can also be made of a reflective material. For example, the aperture unit can be made of a light-absorbing photoresist. During fabrication, the aperture unit can be formed above the pixel-level light source, for example, by etching.

[0095] In block 1130 , a deflection unit is disposed above the aperture unit to deflect the light beam limited by the aperture unit into a predetermined direction.

[0096] In some embodiments, the deflection unit is a collimating deflection unit. In yet other embodiments, the deflection unit may also be a metasurface, which may include an array of micro-nanostructure units formed on a substrate. In some embodiments, the micro-nanostructure units in the array of micro-nanostructure units may include nanopillar structures. In particular, the orthographic projection of the nanopillar structure on the substrate may be a C4 rotationally symmetric pattern. As an example, the nanopillar structure may include a nanocylindrical structure and a nanosquare pillar structure.

[0097] In some embodiments, depending on the wavelength of light used in the application (which may include but is not limited to visible light), the spacing between the above-mentioned multiple micro-nanostructure units is constant and can be selected to be smaller than the wavelength of the light used, such as 700nm, 600nm, 500nm, 350nm, 300nm, 250nm, 200nm, etc.

[0098] In particular, when visible light is used, when the nanocolumn structure unit is a nanocylindrical structure, the diameter of the nanocolumn structure can be selected from the range of 50 nm to 400 nm, for example.

[0099] Although the invention has been described and illustrated in detail in the drawings and foregoing description, such description and illustration are to be considered illustrative or exemplary rather than restrictive; the invention is not limited to the disclosed embodiments. Other variations of the disclosed embodiments can be understood and practiced by those skilled in the art in practicing the claimed invention by studying the drawings, the disclosure, and the appended claims.

[0100] Furthermore, it should be understood that the methods, steps, or processes described above are merely examples. Although the method steps are described in a particular order in the specification, this does not require or imply that the steps must be performed in that particular order, or that all steps shown must be performed to achieve the desired result. Rather, the steps described may be performed in a different order. Additionally or alternatively, certain steps may be omitted, multiple steps may be combined into a single step, and / or a single step may be broken down into multiple steps.

[0101] In the claims, the word "comprising" does not exclude other elements, and the indefinite article "a" or "an" does not exclude a plurality. A single element or other unit can fulfill the functions of multiple items set forth in the claims. The mere fact that certain features are recited in different embodiments or dependent claims does not mean that a combination of these features cannot be used to advantage. The scope of protection of this application covers any possible combination of the various features recited in the various embodiments or dependent claims without departing from the spirit and scope of this application.

[0102] Any reference signs in the claims should not be construed as limiting the scope of the disclosure.

Claims

1. A three-dimensional display device, characterized in that: include: A light source, a pixel unit array having a plurality of pixel units, each of the plurality of pixel units including a plurality of sub-pixels; an aperture unit array, comprising a plurality of aperture units, wherein the plurality of aperture units correspond one-to-one to the plurality of sub-pixels in the plurality of pixel units, and are used to limit the divergence angle of a light beam emitted from each sub-pixel; as well as The collimating and deflecting array comprises a plurality of collimating and deflecting units, wherein the plurality of collimating and deflecting units correspond one-to-one to the plurality of aperture units and are used for collimating and deflecting the light beams restricted by the aperture unit array.

2. The three-dimensional display device according to claim 1, wherein each collimating and deflecting unit is a metasurface, and the metasurface includes a plurality of micro-nanostructure units formed on a substrate. The three-dimensional display device according to claim 2 , wherein each micro-nano structure unit comprises a nano-column structure. The three-dimensional display device according to claim 2 , wherein the spacing between the plurality of micro-nanostructure units is less than 400 nm. 5 . The three-dimensional display device according to claim 3 , wherein when the nano-column structure is a nano-cylindrical structure, a diameter of the nano-cylindrical structure is in a range of 50 nm to 400 nm. 6 . The three-dimensional display device according to claim 1 , wherein the plurality of sub-pixels include a blue sub-pixel, a red sub-pixel, and a green sub-pixel.

7. A three-dimensional display device according to any one of claims 1 to 6, wherein the collimating and deflecting array is designed to collimate and deflect the light emitted by the multiple sub-pixels in each pixel unit to different directions, wherein the different directions correspond to different viewpoints of the three-dimensional display device. 8 . The three-dimensional display device according to claim 2 , wherein the material used to prepare the micro-nano structure unit comprises titanium oxide and silicon nitride.

9. The three-dimensional display device according to any one of claims 1 to 6, wherein the height of each aperture unit is designed so that the angle of light emitted from the center point of each sub-pixel along the highest point of the corresponding aperture unit is no more than 20°.

10. The three-dimensional display device according to any one of claims 1 to 6, wherein the aperture unit array is made of a material having light absorption properties.

11. The three-dimensional display device according to any one of claims 1 to 6, wherein the light source comprises a micro light emitting diode, a liquid crystal display, or an organic light emitting diode.

12. A beam shaping structure, characterized in that: include: Pixel-level light source; an aperture unit, disposed above the pixel-level light source and configured to limit a divergence angle of a light beam emitted from the pixel-level light source; as well as The deflection unit is arranged above the aperture unit and is used for deflecting the light beam limited by the aperture unit. 13 . The beam shaping structure according to claim 12 , wherein the height of the aperture unit is designed so that the angle of light emitted from the pixel-level light source along the highest point of the aperture unit is no greater than 20°.

14. The beam shaping structure according to claim 12, wherein the deflection unit is a metasurface comprising a plurality of micro-nanostructure units formed on a substrate. The beam shaping structure according to claim 14 , wherein each micro-nanostructure unit comprises a nano-cylindrical structure. The beam shaping structure according to claim 14 , wherein a distance between the plurality of micro-nanostructure units is less than 400 nm. 17 . The beam shaping structure according to claim 14 , wherein the pixel-level light source is a pixel or a sub-pixel derived from an image source.

18. The beam shaping structure according to any one of claims 12 to 17, wherein the aperture unit array is made of a material having light absorption properties.

19. An optical device comprising the beam shaping structure according to any one of claims 12 to 18.

20. The optical device according to claim 19, which is a three-dimensional display device.

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