Display panel and manufacturing method therefor, and projection system

Abstract

Provided are a display panel and a manufacturing method therefor, and a projection system. The display panel comprises: a first substrate; a second substrate arranged opposite to the first substrate; a liquid crystal layer, arranged between the first substrate and the second substrate; a reflective layer, arranged on the side of the first substrate facing the second substrate; and a metasurface light-splitting structural layer, arranged on the side of the reflective layer away from the first substrate, wherein the metasurface light-splitting structural layer comprises a plurality of metasurface light-splitting units that are periodically arranged, at least one metasurface light-splitting unit comprises a plurality of metasurface light-splitting and converging structures, and each metasurface light-splitting unit is configured to: split white light reflected by the reflective layer into a plurality of pieces of monochromatic light, and by means of the metasurface light-splitting and converging structure, converge the plurality of pieces of monochromatic light into an area where a plurality of subpixels of the display panel are located.

Description

Display panel, preparation method thereof and projection system TECHNICAL FIELD

[0001] The present disclosure relates to the technical field of display, and in particular to a display panel, a preparation method thereof and a projection system. BACKGROUND

[0002] With the rapid development of display technology, people have higher and higher requirements for display technology. At present, micro projection technology has begun to enter the market and is widely used in personal consumer field and business occasions, and has broad development prospects.

[0003] LCOS (Liquid Crystal On Silicon) projection technology is a new type of reflective liquid crystal projection technology. In order to realize red, green and blue display, the current LCOS projection scheme mainly includes a single-chip LCOS projection scheme and a three-chip LCOS projection scheme. Among them, the three-chip LCOS projection scheme has a large overall volume, which is not conducive to the miniaturization development of the device. The single-chip LCOS projection scheme currently mainly includes two ways of time domain color separation by color film and color wheel. However, the conventional color film has a low transmittance, and the light efficiency loss is about 60%-70%. The color wheel will cause the degradation of display effect due to the influence of frame frequency, and also reduce the light efficiency of the projection system. Therefore, how to improve the optical efficiency of the projection system and reduce the volume of the projection system is one of the important topics for researchers in the field to study.

[0004] It should be noted that the information disclosed in the above background section is only used to strengthen the understanding of the background of the present disclosure, and therefore can include information that does not constitute prior art known to those skilled in the art. SUMMARY

[0005] In one aspect, a display panel is provided, comprising: a first substrate; and a second substrate disposed opposite to the first substrate; a liquid crystal layer disposed between the first substrate and the second substrate;

[0006] a reflective layer disposed on a side of the first substrate facing the second substrate; and

[0007] a metasurface light splitting structure layer disposed on a side of the reflective layer away from the first substrate, the metasurface light splitting structure layer comprising a plurality of metasurface light splitting units arranged periodically, at least one of the metasurface light splitting units comprising a plurality of metasurface light splitting and converging structures,

[0008] wherein the metasurface light splitting unit is configured to separate white light reflected by the reflective layer into a plurality of monochromatic lights, and converge the plurality of monochromatic lights to an area where a plurality of sub-pixels of the display panel via the metasurface light splitting and converging structures.

[0009] According to some exemplary embodiments, an orthographic projection of the metasurface light-splitting structure layer on the first substrate falls within an orthographic projection of the reflective layer on the first substrate.

[0010] According to some exemplary embodiments, the metasurface spectroscopic unit includes a plurality of periodically arranged metasurface nanopillars and a filling layer filling the gaps between the plurality of metasurface nanopillars, wherein the metasurface nanopillars are rotationally symmetric columnar structures.

[0011] According to some exemplary embodiments, the metasurface light splitting structure layer has a lens phase Ψ lens (x, y, f, λ), the lens phase Ψ lens (x, y, f, λ) satisfies equation (1):

[0012] Wherein, x, y are the coordinate positions in the two-dimensional coordinate system constructed by the plane where the metasurface light-splitting structure layer is located, λ is the wavelength of light, and f is the focal length of the equivalent lens of the metasurface light-splitting structure layer;

[0013] The display panel further includes a first alignment layer located between the metasurface light-splitting structure layer and the liquid crystal layer, wherein the first alignment layer has a first thickness, wherein:

[0014] The focal length f of the equivalent lens is equal to the first thickness.

[0015] According to some exemplary embodiments, the refractive index of the material of the metasurface nanorods is greater than the refractive index of the material of the filling layer.

[0016] According to some exemplary embodiments, the refractive index of the material of the metasurface nanorods is greater than or equal to 1.5; and / or,

[0017] The refractive index of the material of the filling layer is greater than or equal to 1 and less than or equal to 1.3.

[0018] According to some exemplary embodiments, the metasurface light splitting structure layer has a deflection phase Ψ d (x, y, λ), the deflection phase Ψ d (x, y, λ) satisfies equation (2):

[0019] Wherein, θ is the off-axis angle of the light beam with a wavelength of λ on the x-axis, wherein the x-axis is the transverse coordinate axis in the two-dimensional coordinate system constructed by the plane where the metasurface spectroscopic structure layer is located.

[0020] According to some exemplary embodiments, the orthographic projection of the metasurface nanorod on the first substrate has a first projection shape, and the first projection shape is at least one of a circle, a square, or a rectangle.

[0021] According to some exemplary embodiments, in at least one of the super-surface light splitting units, the first projected shapes of the plurality of super-surface nano-pillars are not completely identical; and the thicknesses of the plurality of super-surface nano-pillars in the light-out direction are identical.

[0022] According to some exemplary embodiments, in at least one of the super-surface light splitting units, the first projected shapes of the plurality of super-surface nano-pillars are identical; and the thicknesses of the plurality of super-surface nano-pillars in the light-out direction are not completely identical.

[0023] According to some exemplary embodiments, in at least one of the super-surface light splitting and converging structures, the period of the super-surface nano-pillars is ≤ λ / 2, where λ is the wavelength range of the light transmitted by the super-surface light splitting and converging structure.

[0024] According to some exemplary embodiments, the super-surface light splitting structure layer further comprises a substrate portion, and the plurality of super-surface light splitting units are located on the side of the substrate portion away from the reflective layer.

[0025] According to some exemplary embodiments, the material of the reflective layer comprises Al; and / or,

[0026] The material of the substrate portion comprises SiO2; and / or,

[0027] The material of the super-surface nano-pillars comprises one of TiO2, SiNx, and GaNx.

[0028] According to some exemplary embodiments, the display panel further comprises: a common electrode located between the liquid crystal layer and the second substrate; a light shielding layer located on the side of the reflective layer close to the first substrate; and a driving circuit layer located on the side of the light shielding layer close to the first substrate.

[0029] In another aspect, a method for manufacturing a display panel is provided, comprising:

[0030] providing a first substrate;

[0031] forming a reflective layer on the first substrate;

[0032] forming a substrate portion on the side of the reflective layer away from the first substrate;

[0033] forming, in sequence, a super-surface light splitting structure material layer, a first mask layer, and an etching glue layer on the side of the substrate portion away from the first substrate;

[0034] performing a patterning process on the etching glue layer to form a pattern;

[0035] The pattern on the etching adhesive layer is transferred to the first mask layer by an etching process, and the etching adhesive layer is removed;

[0036] The pattern on the first mask layer is transferred to the metasurface nano pillar material layer by continuing the etching process, and the first mask layer is removed, thereby obtaining a plurality of metasurface nano pillars;

[0037] The gaps between the plurality of metasurface nano pillars are filled with adhesive material as a filling layer of a plurality of metasurface structure units to form a metasurface light splitting structure layer, thereby forming a first part comprising a first substrate, a reflective layer and a metasurface light splitting structure layer;

[0038] The method further comprises:

[0039] A second substrate is provided;

[0040] A liquid crystal cell is formed on the second substrate to form a second part comprising a second substrate and a liquid crystal cell;

[0041] The first part and the second part are aligned and laminated to form a display panel.

[0042] In yet another aspect, a projection system is provided, wherein the projection system comprises the display panel according to any one of the above.

[0043] According to some exemplary embodiments, the projection system further comprises a light source, a collimating lens, a polarizer, a polarization beam splitter and a projection lens group;

[0044] The light emitted by the light source passes through the collimating lens, the polarizer and the polarization beam splitter in sequence to enter the display panel to form incident light;

[0045] The incident light forms emergent light after reflection, light splitting and focusing by the display panel; and

[0046] The emergent light passes through the polarization beam splitter and the projection lens group in sequence to form a projection image.

[0047] According to some exemplary embodiments, the projection system has an emergent light with a divergence angle less than or equal to 20°.

[0048] According to some exemplary embodiments, the light source comprises at least one of a white light LED light source, an RGB LED light source or a laser diode light source. BRIEF DESCRIPTION OF DRAWINGS

[0049] The above and other objects, features and advantages of the present disclosure will become more apparent from the following description of embodiments of the present disclosure taken in conjunction with the accompanying drawings, in which:

[0050] FIG. 1 is a structural block diagram of a projection system according to an embodiment of the present disclosure;

[0051] FIG. 2 is a partial planar schematic diagram of a projection system according to an embodiment of the present disclosure;

[0052] FIG. 3 is a partial structural schematic diagram of a display panel according to an exemplary embodiment of the present disclosure;

[0053] FIG. 4 is a partial planar schematic diagram of a metasurface light-splitting structure layer according to some exemplary embodiments of the present disclosure; FIG. 5 is a planar schematic diagram of a single metasurface light-splitting unit in the area of the dashed line box in FIG. 4;

[0054] FIG. 6A is a partial structural schematic diagram of a metasurface light-splitting structure layer according to some exemplary embodiments of the present disclosure; FIG. 6B is a planar schematic diagram of an orthographic projection of a metasurface nano-pillar on a first substrate according to some exemplary embodiments of the present disclosure;

[0055] FIG. 7 is a graph of the correspondence between the structural diameter of a cylindrical nano-pillar and the phase according to an exemplary embodiment of the present disclosure;

[0056] FIG. 8 is a graph of the relationship between the response wavelength and the light transmittance of a metasurface light-splitting structure layer according to an exemplary embodiment of the present disclosure;

[0057] FIG. 9A-FIG. 9C are planar schematic diagrams of metasurface nano-pillars responding to light of different wavelengths, respectively, according to exemplary embodiments of the present disclosure;

[0058] FIG. 10 is a planar schematic diagram of a metasurface light-splitting unit according to an exemplary embodiment of the present disclosure;

[0059] FIG. 11A is a planar schematic diagram of a red light modulating metasurface light-splitting and converging structure included in a single metasurface light-splitting unit according to an exemplary embodiment of the present disclosure; FIG. 11B is a planar schematic diagram of a green light modulating metasurface light-splitting and converging structure included in a single metasurface light-splitting unit according to an exemplary embodiment of the present disclosure; FIG. 11C is a planar schematic diagram of a blue light modulating metasurface light-splitting and converging structure included in a single metasurface light-splitting unit according to an exemplary embodiment of the present disclosure;

[0060] FIG. 12A-FIG. 12L are partial cross-sectional diagrams in the processing of a display panel, respectively, according to exemplary embodiments of the present disclosure;

[0061] FIG. 13 is a processing flow diagram of a display panel according to exemplary embodiments of the present disclosure;

[0062] FIG. 14 is a structural schematic diagram of a projection system according to some embodiments of the present disclosure.

[0063] It is to be noted that the size of the layers, structures, or regions in the drawings can be exaggerated or reduced for clarity, i.e. the drawings are not necessarily drawn to scale. DETAILED DESCRIPTION

[0064] In order to make the objects, technical solutions, and advantages of the embodiments of the present disclosure clearer, the technical solutions of the embodiments of the present disclosure will be described clearly and completely below with reference to the drawings of the embodiments of the present disclosure. Obviously, the described embodiments are some but not all of the embodiments of the present disclosure. Based on the described embodiments of the present disclosure, all other embodiments obtained by a person of ordinary skill in the art without creative effort belong to the scope of protection of the present disclosure.

[0065] It should be noted that in the drawings, the size and relative size of the elements can be exaggerated for clarity and / or descriptive purposes. Thus, the size and relative size of the elements in the drawings is not necessarily drawn to scale. In the description and drawings, identical or similar reference signs indicate identical or similar components.

[0066] Unless otherwise defined, technical terms or scientific terms used in the present disclosure should be understood as having the same meaning as commonly understood by one of ordinary skill in the art. The terms "first", "second", and similar terms used in the present disclosure do not denote any order, quantity, or importance, but are used to distinguish different components. The terms "include" or "contain" and similar terms mean that the elements or objects before the terms encompass the elements or objects listed after the terms and their equivalents, and do not exclude other elements or objects.

[0067] In this document, unless otherwise specifically stated, directional terms such as "upper", "lower", "left", "right", "inner", "outer", and the like are used with reference to the orientation or position shown in the drawings, and are used only for the convenience of describing the present disclosure, and do not indicate or imply that the devices, elements, or components referred to must have a particular orientation, be constructed or operated in a particular orientation. It should be understood that when the absolute position of the described object changes, the relative positional relationship they represent may also change accordingly. Therefore, these directional terms cannot be understood as a limitation on the present disclosure.

[0068] It should be noted that, in this document, the expression “same layer” refers to a layer structure formed by using the same film forming process to form a film layer for forming a specific pattern, and then patterning the film layer by a one-time patterning process using the same mask plate. Depending on the specific pattern, the one-time patterning process can include multiple exposure, development or etching processes, and the specific pattern in the formed layer structure can be continuous or discontinuous. That is, the plurality of elements, components, structures and / or parts located in the “same layer” are composed of the same material and are formed by the same patterning process. Generally, the plurality of elements, components, structures and / or parts located in the “same layer” have approximately the same thickness.

[0069] Those skilled in the art should understand that, in this document, unless otherwise specified, the expression “height” or “thickness” refers to the dimension along the surface of each film layer arranged perpendicular to the display panel or LCOS device, i.e. the dimension along the light output direction of the display panel or LCOS device, or the dimension along the normal direction of the display panel or LCOS device.

[0070] In this document, the directional expressions “first direction”, “second direction” and “third direction” are used to describe different directions along the metasurface light splitting unit, such as the horizontal direction and the vertical direction of the metasurface light splitting unit. It should be understood that such representation is only an exemplary description, and is not a limitation of the present disclosure.

[0071] “About” in the present disclosure means not strictly limited to the limit, allowing the value within the range of process and measurement error.

[0072] Unless otherwise specifically stated, the relevant terms appearing in this document can be explained as follows.

[0073] Metasurface: an electromagnetic wave modulation device constructed by high refractive index material or metal material unit structure with a scale smaller than the wavelength order, which can achieve various electromagnetic wave effects by designing the arrangement of the relevant unit structure. For example, it can achieve phase deflection or focusing effects of light of different wavelengths.

[0074] LCOS (Liquid Crystal On Silicon, Liquid Crystal on Silicon) device: is one of the key technologies of reflective liquid crystal projectors and back projection televisions. Its structure is to use semiconductor process to manufacture a driving panel (also called CMOS substrate) on a silicon wafer, then grind the crystal to a flat surface and coat a reflective layer (such as aluminum) as a mirror, form a CMOS substrate, then bond the CMOS substrate with a glass substrate containing a transparent electrode to form an LCOS device.

[0075] In a display formed by using an LCOS device, a driving CMOS substrate (a CMOS structure including a source, a gate, a drain and a storage capacitor, a light shielding layer and a reflective layer) formed by a semiconductor process is bonded with a liquid crystal cell containing a transparent electrode to realize a reflective display. Compared with a traditional transmissive liquid crystal display, the reflective display device has a higher pixel aperture ratio because the driving circuit is placed under the pixel opening without causing a shielding effect, thereby bringing a higher light efficiency.

[0076] In order to realize color projection, in the related art, LCOS projection schemes mainly include three types: (1) a single-chip LCOS projection scheme constructed by using an LCOS device with a color film; (2) a single-chip colorless film LCOS projection scheme constructed by using a single-chip colorless film LCOS device in combination with a color wheel for time-domain RGB color separation; and (3) a three-chip LCOS projection scheme constructed by using three colorless film LCOS devices in combination with RGB light splitting and beam combining optical paths. Among them, the light efficiency loss (the light efficiency is only about 30%) caused by the absorption type color film leads to a low light efficiency of the single-chip color film LCOS projection scheme. The single-chip colorless film LCOS scheme uses a color wheel for color selection, and due to the influence of frame frequency, it also causes degradation of display effect and light efficiency loss. The three-chip LCOS projection scheme has a large overall volume, which is not conducive to the miniaturization development of the device, and the color selection process of the color separation mirror also causes a certain light efficiency loss.

[0077] In an embodiment of the present disclosure, a display panel is provided. The display panel includes: a first substrate; a second substrate disposed opposite the first substrate; a liquid crystal layer disposed between the first substrate and the second substrate; a reflective layer disposed on a side of the first substrate facing the second substrate; and a metasurface light splitting structure layer disposed on a side of the reflective layer away from the first substrate. The metasurface light splitting structure layer includes a plurality of periodically arranged metasurface light splitting units, and at least one metasurface light splitting unit includes a plurality of metasurface light splitting and converging structures. The metasurface light splitting unit is configured to separate white light reflected by the reflective layer into a plurality of monochromatic lights, and converge the plurality of monochromatic lights to a plurality of sub-pixel regions of the display panel through the metasurface light splitting and converging structures. Exemplarily, the display panel can be a display panel including an LCOS device.

[0078] By adopting the metasurface light splitting structure layer, the wavelength-dependent characteristics and phase superposition function of the metasurface structure are utilized to make the white light beam focus and deflect to different angles after reflection as red, green and blue lights, thereby realizing color reflective display without color film. Compared with the light efficiency loss caused by the absorption type color film, the light efficiency of the color LCOS device is improved by about 3 times. Further combined with a single-chip LCOS projection system with a white light source, the three-chip projection system can have a more compact volume.

[0079] FIG. 1 is a structural block diagram of a projection system according to an embodiment of the present disclosure.

[0080] Exemplarily, in an embodiment of the present disclosure, referring to FIG. 1, the projection system 100 includes a light source 1, a collimating lens 2, a polarizer 3, a polarization beam splitter 4, a display panel 5, and a projection lens group 6. For example, the display panel 5 can include an LCOS device.

[0081] The light emitted by the light source passes through the collimating lens 2, the polarizer 3, and the polarization beam splitter 4 in sequence to enter the display panel 5 to form incident light. After reflection, light splitting, and focusing of the incident light by the display panel 5, emergent light is formed. The emergent light passes through the polarization beam splitter 4 and the projection lens group 6 in sequence to form a projection image.

[0082] In some embodiments, the projection image is at a distance of 1 meter to 3 meters from the projection lens group 6 in the projection system, so as to realize magnified imaging of image information at a certain distance, and finally project the signal in the display panel 5 as an image size required to be viewed by a user.

[0083] FIG. 2 is a partial plan view of a projection system according to an embodiment of the present disclosure.

[0084] Exemplarily, in some embodiments of the present disclosure, referring to FIG. 2, the projection system 100 can include a display area AA. The projection system further includes a plurality of pixel units PX in the display area AA, which are arranged in the display area AA in a first direction X and a second direction Y.

[0085] In an embodiment of the present disclosure, the display area AA can have various shapes. For example, the display area AA can be provided in various shapes such as a polygon (for example, a rectangle) including a straight side, a circle including a curved side, an ellipse, and the like, and a semi-circle, a semi-ellipse, and the like including a straight side and a curved side. In an embodiment of the present disclosure, the display area AA is provided as one area having a quadrilateral shape including a straight side, and it should be understood that this is merely an exemplary embodiment of the present disclosure, and is not a limitation of the present disclosure.

[0086] The pixel unit PX is the smallest unit for displaying an image. The pixel units PX can be provided in a plurality to be arranged in a matrix form along a row extending in the first direction X and a column extending in the second direction Y. However, embodiments of the present disclosure do not specifically limit the arrangement form of the pixel units PX, and the pixel units PX can be arranged in various forms. For example, the pixel units PX can be arranged such that a direction inclined with respect to the first direction X and the second direction Y becomes a column direction, and a direction intersecting the column direction becomes a row direction.

[0087] One pixel unit PX can include a plurality of sub-pixels. For example, one pixel unit PX can include three sub-pixels, i.e., a first sub-pixel sp1, a second sub-pixel sp2, and a third sub-pixel sp3. For example, the first sub-pixel sp1 emits red light, the second sub-pixel sp2 emits green light, and the third sub-pixel sp3 emits blue light. It should be understood that this is only an exemplary embodiment of the present disclosure, and is not a limitation of the present disclosure.

[0088] FIG. 3 is a schematic diagram of a partial structure of a display panel according to an exemplary embodiment of the present disclosure.

[0089] Exemplarily, in some embodiments of the present disclosure, with reference to FIG. 3, the display panel 5 can include a first substrate 51, a second substrate 60 disposed opposite to the first substrate 51, and a liquid crystal layer 57 disposed between the first substrate 51 and the second substrate 60.

[0090] In some embodiments, the first substrate 51 can include a silicon-based substrate. Accordingly, the display panel 5 can be an LCOS device. It should be understood that in embodiments of the present disclosure, the structure of the display panel is described by taking the LCOS device as an example, but the display panel provided by embodiments of the present disclosure can not be limited to the LCOS device, for example, the first substrate 51 can include a substrate of an array substrate of a conventional liquid crystal display panel.

[0091] In some embodiments, the second substrate 60 can include a glass substrate.

[0092] Exemplarily, with continued reference to FIG. 3, the display panel 5 can further include a first alignment layer 56 and a second alignment layer 58. The second alignment layer 58 is located on a side of the liquid crystal layer 57 close to the second substrate 60, and the first alignment layer 56 is located on a side of the liquid crystal layer 57 away from the second substrate 60.

[0093] In some embodiments, the material of the first alignment layer 56 and the second alignment layer 58 can be polyimide (PI).

[0094] Exemplarily, with continued reference to FIG. 3, the display panel 5 can further include a reflective layer 54 disposed on a side of the first substrate 51 facing the second substrate 60, and a metasurface light splitting structure layer 55 disposed on a side of the reflective layer 54 away from the first substrate 51.

[0095] Exemplarily, as shown in FIG. 4, the metasurface light splitting structure layer 55 can include a plurality of metasurface light splitting units 500 arranged periodically. With continued reference to FIG. 3, at least one metasurface light splitting unit 500 includes a plurality of metasurface light splitting converging structures, for example, a red light modulating metasurface light splitting converging structure 501, a green light modulating metasurface light splitting converging structure 502, and a blue light modulating metasurface light splitting converging structure 503.

[0096] Exemplarily, in the embodiments of the present disclosure, the area where the plurality of metasurface light splitting units 500 arranged periodically can be the area where the plurality of pixel units are arranged periodically. It should be understood that the pixel units PX can be arranged one-to-one with the metasurface light splitting units 500. The area where the plurality of metasurface light splitting and converging structures are located can be the area where the plurality of sub-pixels are located. It should be understood that the sub-pixels can be arranged one-to-one with the metasurface light splitting and converging structures. For example, the area where the red light modulation metasurface light splitting and converging structure 501 is located can be the area where the red sub-pixel R is located, the area where the green light modulation metasurface light splitting and converging structure 502 is located can be the area where the green sub-pixel G is located, and the area where the blue light modulation metasurface light splitting and converging structure 503 is located can be the area where the blue sub-pixel B is located.

[0097] In the area where the pixel units are located, the metasurface light splitting unit 500 processes the input white light to separate a plurality of monochromatic lights, and converges the separated plurality of monochromatic lights to the areas where the different sub-pixels are located, respectively. Further, the converged monochromatic light is emitted through the liquid crystal layer, thereby forming an image signal.

[0098] For example, the metasurface light splitting unit 500 is configured to separate the white light reflected by the reflection layer 54 into a plurality of monochromatic lights, and converge the monochromatic lights to the areas where the different sub-pixels are located through the metasurface light splitting and converging structures. For example, the separated red light is converged to the area where the red sub-pixel R is located through the red light modulation metasurface light splitting and converging structure 501. The separated green light is converged to the area where the green sub-pixel G is located through the green light modulation metasurface light splitting and converging structure 502. The separated blue light is converged to the area where the blue sub-pixel B is located through the blue light modulation metasurface light splitting and converging structure 503.

[0099] Exemplarily, the orthographic projection of the metasurface light splitting structure layer 55 on the first substrate 51 falls within the orthographic projection of the reflection layer 54 on the first substrate 51. Through the design of the reflection layer, at least most of the incident light can be reflected into the metasurface light splitting structure layer 55, and then enter the area where the corresponding sub-pixel is located through the phase deflection and light converging effect of the metasurface light splitting structure layer 55.

[0100] In some embodiments, the material of the reflection layer can include aluminum.

[0101] In some example embodiments, in order to realize the color display, the incident light needs to be separated into red, green and blue light after passing through the super surface light splitting structure layer 55 and converged into the area where the corresponding sub-pixel is located. The super surface light splitting structure layer 55 is provided with a liquid crystal layer 57 on the side close to the second substrate 60. By controlling the state of the liquid crystal in the liquid crystal layer 57, the transmittance of the light in the area where the different sub-pixels are located in the liquid crystal layer can be controlled, so as to realize the display of different pictures. For example, in combination with reference to FIG. 3 and FIG. 14, after the light in the area where the sub-pixel is located passes through the liquid crystal layer, under the action of the external projection lens, the projection image can be formed.

[0102] In some embodiments, still referring to FIG. 3, the display panel 5 can further include a common electrode 59 located between the liquid crystal layer 57 and the second substrate 60. For example, the material of the common electrode 59 can include a transparent electrode material, such as ITO. The display panel 5 can further include a light shielding layer 53 located on the side of the reflective layer 54 close to the first substrate. The display panel 5 can further include a driving circuit layer 52 located on the side of the light shielding layer 53 close to the first substrate. The driving circuit layer 52 can include at least one transistor. For example, the transistor can include a gate 521, a source 522, a drain 523 and an active layer 524. The driving circuit layer 52 can further include at least one capacitor 525.

[0103] For example, the light shielding layer 53 can be arranged at intervals, which can reduce the light entering the driving circuit layer below, and is beneficial to improve the stability of the driving circuit.

[0104] For example, the driving circuit layer 52 and the common electrode 59 can be electrically connected with an external driving chip. By the signal of the external driving chip, the voltage between the common electrode 59 and the driving circuit layer 52 is controlled, so as to control the state of the liquid crystal in the liquid crystal layer 57 located between the common electrode 59 and the driving circuit layer 52. By controlling the deflection of the liquid crystal in the liquid crystal layer 57, the light transmittance of the area where the corresponding sub-pixel is located can be adjusted, so that the light in each sub-pixel area realizes different degrees of light transmission in the liquid crystal layer, thereby realizing the display of different gray scales and different pictures.

[0105] FIG. 4 is a partial plan view of a super surface light splitting structure layer according to some example embodiments of the present disclosure; FIG. 5 is a plan view of a single super surface light splitting unit in the area of the dashed line frame in FIG. 4; FIG. 6A is a partial structural view of a super surface light splitting structure layer according to some example embodiments of the present disclosure; FIG. 6B is a plan view of the orthographic projection of a super surface nano-pillar on a first substrate according to some example embodiments of the present disclosure.

[0106] In some embodiments, in combination with reference to FIGS. 3-6A, the metasurface light splitting unit 500 includes a plurality of periodically arranged metasurface nano-pillars 551 and a filling layer 552 filled in the gaps between the plurality of metasurface nano-pillars.

[0107] In some embodiments, the refractive index of the material of the metasurface nano-pillars 551 is greater than the refractive index of the material of the filling layer 552.

[0108] In some embodiments, the refractive index of the material of the metasurface nano-pillars 551 is greater than or equal to 1.5.

[0109] In some embodiments, the material of the metasurface nano-pillars 551 includes silicon nitride, gallium nitride, titanium oxide, or other high refractive index materials.

[0110] In some embodiments, the refractive index of the material of the filling layer 552 is greater than or equal to 1 and less than or equal to 1.3. For example, the material of the filling layer 552 can include a low refractive index filling glue, such as a filling glue with a refractive index of 1.3.

[0111] Exemplarily, the metasurface nano-pillar is a rotationally symmetric columnar structure.

[0112] In some embodiments, with reference to FIG. 6A, the orthographic projection of the metasurface nano-pillar on the first substrate has a first projection shape, which can be a circular shape.

[0113] In other embodiments, with reference to FIG. 6B, the first projection shape m1 can be at least one of a circular shape, a square shape, or a rectangular shape.

[0114] Exemplarily, the height of the metasurface nano-pillar along the third direction Z is H, and the third direction Z is perpendicular to both the first direction X and the second direction Y. Alternatively, the third direction Z is the direction of the first substrate 51 towards the second substrate 60, i.e., the light-out direction.

[0115] The first projection shape of the metasurface nano-pillar and the height H of the metasurface nano-pillar can be specifically designed according to actual needs, and the embodiments of the present disclosure do not limit them.

[0116] In some embodiments, all the metasurface nano-pillars included in the metasurface light splitting structure layer are cylindrical nano-pillars.

[0117] In some embodiments, all the metasurface nano-pillars included in the metasurface light splitting structure layer are square nano-pillars, such as rectangular nano-pillars or square nano-pillars.

[0118] In some embodiments, part of all the metasurface nano-pillars included in the metasurface light splitting structure layer are cylindrical nano-pillars, and the other part are square nano-pillars.

[0119] Exemplarily, in combination with reference to FIG. 3 and FIG. 6A, the super-surface light-splitting structure layer 55 can further include a substrate portion 553. The plurality of super-surface light-splitting units 500 are located on a side of the substrate portion 553 away from the reflective layer 54. FIG. 6A shows a unit period P of a single super-surface nano-pillar. For example, the unit period P of the super-surface nano-pillar is 400 nm. The unit period P can include: a diameter of a single complete super-surface nano-pillar; and a width of one of the following: a half of the filling layer adjacent to the super-surface nano-pillar and a gap between the super-surface nano-pillar and the filling layer.

[0120] In some embodiments, the material of the substrate portion 553 can include silicon oxide.

[0121] It should be noted that in the display panel such as the LCOS device provided in the embodiments of the present disclosure, the super-surface light-splitting structure layer realizes light splitting of white light, mainly based on the unit structure of the super-surface nano-pillar. By designing the arrangement of the super-surface nano-pillar, the super-surface light-splitting and converging structure can have a corresponding response wavelength, so that the super-surface light-splitting and converging structure can modulate light at the response wavelength. Accordingly, by designing the super-surface light-splitting structure layer to include different super-surface light-splitting and converging structures, the white light can be divided into red light, blue light, and green light. Moreover, by designing the arrangement of the super-surface nano-pillar, the phase can also be modulated, so that the super-surface light-splitting and converging structure also has the functions of focusing lens and deflecting light, thereby realizing deflection of the converged light of the corresponding color light to the region where the sub-pixel corresponding to the super-surface light-splitting and converging structure is located.

[0122] In some embodiments, in order to realize the convergence and deflection of the light beam of the modulated wavelength, the super-surface light-splitting structure layer needs to express the phase values of the focusing lens and the deflection light at the corresponding wavelength, which can be directly realized by phase superposition.

[0123] In some embodiments, the super-surface light-splitting structure layer has a lens phase Ψ lens (x, y, f, λ). Wherein, the lens phase represents that the super-surface light-splitting structure layer can control the phase distribution of the light wave through the design of the super-surface structure unit, thereby realizing the manipulation of the wave front and realizing the effect equivalent to the focusing of the lens. The lens phase Ψ lens (x, y, f, λ) satisfies equation (1):

[0124] Wherein, x and y are the coordinate positions of the two-dimensional coordinate system of the plane component where the metasurface spectroscopic structure layer is located. For example, the two-dimensional coordinate system can be a two-dimensional coordinate system of the plane where the first direction X and the second direction Y are located. λ is the wavelength of light, and f is the focal length of the equivalent lens of the metasurface spectroscopic structure layer. It should be noted that the x-axis of the two-dimensional coordinate system can be parallel to the first direction X, and the y-axis can be parallel to the second direction Y. Alternatively, the x-axis of the two-dimensional coordinate system can have a certain angle with the first direction X, and the y-axis can have a certain angle with the second direction Y.

[0125] Through the design of the metasurface spectroscopic structure layer, a geometric lens modulation effect equivalent to a focal length of f can be achieved.

[0126] 3 , the display panel 5 further includes a first alignment layer 56 located between the metasurface light-splitting structure layer 55 and the liquid crystal layer 57. The first alignment layer 56 has a first thickness h1.

[0127] In some embodiments, the focal length f of the equivalent lens of the metasurface spectroscopic structure layer is equal to the first thickness h1, so that multiple monochromatic lights can be precisely converged into the partial liquid crystal layer of the corresponding sub-pixel, while at the same time being beneficial to increasing the light intensity in the color conversion sub-area and improving the display brightness.

[0128] For the off-axis light beam, it is equivalent to the optical element expressing a deflection phase.

[0129] In some embodiments, the metasurface light splitting structure layer has a deflection phase Ψ d (x, y, λ). The deflection phase refers to the phase corresponding to the deflection of the propagation direction of the light wave after the light passes through the metasurface spectroscopic structure layer. d (x, y, λ) satisfies equation (2):

[0130] Wherein, θ is the off-axis angle of the light beam with a wavelength of λ on the x-axis. Wherein, the x-axis is the transverse coordinate axis in the two-dimensional coordinate system constructed by the plane where the metasurface light-splitting structure layer is located.

[0131] By calculating the deflection angle of the corresponding wavelength, the phase distribution of the off-axis light beam deflection device can be obtained.

[0132] By combining the lens phase and off-axis deflection phase of the metasurface, off-axis focusing control of a certain wavelength light beam can be achieved.

[0133] In some embodiments, the phase of the off-axis focusing of the metasurface light splitting structure layer The distribution satisfies:

[0134] Among them, the phase of off-axis focusing For the lens phase Ψ lens The sum of the deflection phase Ψd(x, y, λ) and the lens phase Ψ(x, y, f, λ) can simultaneously embody the relationship between the focusing and deflection phases of light and the coordinate position of the super surface nano pillar, the wavelength of light, the off-axis angle θ, and the focal length f of the equivalent lens. By designing the super surface light splitting structure layer to respond to different deflection angles for different wavelengths, the color separation and light splitting effect of white light can be achieved after the white light is incident on the super surface light splitting structure layer. Therefore, the super surface light splitting structure can achieve the color filter effect.

[0135] It should be noted that the off-axis angle θ of light is determined by (x, y) and the center of the sub-pixel corresponding to the (x, y) position.

[0136] It should also be noted that the off-axis focusing phase of the super surface light splitting structure layer is greater than or equal to 0 and less than or equal to 2π.

[0137] Since the super surface light splitting structure layer includes periodically arranged super surface nano pillars, the light transmittance of the super surface light splitting structure layer is high, and the inventors have found that the light transmittance can be greater than 90% through research. The focusing efficiency of the super surface light splitting and converging structure can reach 80%, and the focusing efficiency of the mixed response device of different super surface light splitting and converging structures in the super surface structure unit can reach 50-60%. Compared with the scheme of setting a color filter, the display panel of the LCOS device provided in the embodiments of the present application can greatly improve the light utilization rate.

[0138] In some embodiments, as shown in FIG. 6A, the super surface nano pillar is a cylindrical nano pillar. The bottom surface of the super surface nano pillar 551 is arranged on the base 553, and the cylindrical side of the super surface nano pillar 551 is wrapped by the filling layer 552. The refractive index of the material of the super surface nano pillar 551 is higher than the refractive index of the material of the filling layer 552, so that the separation and focusing of white light can be better achieved.

[0139] In some embodiments, as shown in FIG. 4, the super surface light splitting structure layer can include a plurality of super surface light splitting units 500. The plurality of super surface light splitting units 500 can be arranged in an array.

[0140] In some embodiments, as shown in FIG. 5, in each metasurface light splitting unit, a plurality of different metasurface light splitting and converging structures are arranged, such as a red light modulating metasurface light splitting and converging structure 501, a green light modulating metasurface light splitting and converging structure 502, and a blue light modulating metasurface light splitting and converging structure 503. Each metasurface light splitting and converging structure can include a plurality of metasurface nanocolumns 551. Exemplarily, the metasurface nanocolumns 551 can be cylindrical nanocolumns. The periods of the cylindrical nanocolumns can not be the same. For example, the diameters of the different cylindrical nanocolumns can not be exactly the same.

[0141] In some embodiments, in at least one metasurface light splitting unit, the first projected shapes of the plurality of metasurface nanocolumns are the same; and the thicknesses of the plurality of metasurface nanocolumns in the light emission direction are not exactly the same.

[0142] It should be noted that not exactly the same means at least two are not the same. For example, in the plurality of different cylindrical nanocolumns, the diameters of at least two of the cylindrical nanocolumns are not the same. For another example, in the plurality of different square nanocolumns, the heights of at least two of the square nanocolumns are not the same.

[0143] It should be further noted that the cylindrical nanocolumns belong to transmission type unit structures, and only one period of the cylindrical nanocolumns is shown in FIG. 6A. In specific implementation, phase modulation can be achieved by changing the radius of the cylindrical nanocolumn or the height of the cylindrical nanocolumn, and the response wavelength of the metasurface light splitting and converging structure can be determined by designing the period P of the cylindrical nanocolumn.

[0144] In some embodiments, in each metasurface light splitting unit, the metasurface nanocolumns in different metasurface light splitting and converging structures can be square nanocolumns. The periods of the square nanocolumns can not be the same.

[0145] In some embodiments, the phase of the metasurface nanocolumn satisfies the following formula (4):

[0146] wherein n eff is the equivalent refractive index of the metasurface light splitting and converging structure, λ is the wavelength range of the light to which the metasurface light splitting and converging structure responds, and H is the height of the metasurface nanocolumn in the direction perpendicular to the substrate. The phase of the metasurface nanocolumn embodies the phase modulation effect of a single metasurface nanocolumn on light. It should be noted that the equivalent refractive index n eff is related to parameters such as the size (e.g., radius or side length) of the metasurface nanocolumn in the plane parallel to the first substrate, the refractive index of the material of the metasurface nanocolumn, and the refractive index of the material of the filling layer.

[0147] Exemplarily, the super surface nano pillar can be formed by a deposition process and a patterning process, and H can be determined in combination with the preparation process capability of the super surface nano pillar, such as a thin film deposition process. After H is fixed, the required phase can be achieved by designing the radius of the super surface nano pillar.

[0148] FIG. 7 is a diagram of the correspondence between the diameter of a cylindrical nano pillar and the phase according to an exemplary embodiment of the present disclosure; and FIG. 8 is a diagram of the relationship between the response wavelength and the light transmittance of a super surface light splitting structure layer according to an exemplary embodiment of the present disclosure.

[0149] In some embodiments, referring to FIG. 7, the super surface nano pillar is a cylindrical nano pillar. In this case, the abscissa is the diameter of the cylindrical nano pillar, and the ordinate is the phase value of light of different wavelengths, which ranges from 0 to 2π. When the height of the cylindrical nano pillar is fixed, the diameter of the cylindrical nano pillar is adjusted to achieve different phase modulation of light of different wave bands. For example, FIG. 7 shows the phase expression of a group of cylindrical nano pillars with diameters between 90 nm and 350 nm in the range of 0-2π. Since the super surface light splitting structure layer needs to modulate RGB three wavelengths, different phase expression values need to be given for the three wavelengths of 450 nm / 532 nm / 620 nm to perform structure screening that can achieve corresponding phase solutions.

[0150] In some embodiments, the relationship between the response wavelength and the transmittance of the super surface light splitting structure layer is shown in FIG. 8. In this case, the abscissa is the wavelength range of light, and the ordinate is the transmittance of light of different wavelengths in different super surface light splitting and converging structures. The cylindrical nano pillar designed for a specific wavelength range (i.e., the wavelength range corresponding to the light to be modulated by the super surface light splitting and converging structure) has a relatively higher transmittance in a certain wavelength range, and a low transmittance in a non-design wavelength range. Therefore, according to the wavelength sensitivity of the cylindrical nano pillar, the red light modulation super surface light splitting and converging structure, the blue light modulation super surface light splitting and converging structure, and the green light modulation super surface light splitting and converging structure can be combined to achieve the wavelength modulation effect under white light incidence.

[0151] FIGS. 9A-9C are respectively plan views of super surface nano pillars responding to light of different wavelengths according to exemplary embodiments of the present disclosure.

[0152] In some embodiments, in each super surface light splitting and converging structure, the period P of the super surface nano pillar is less than or equal to λ / 2, where λ is the wavelength range of the light modulated by the super surface light splitting and converging structure. Therefore, the accuracy of the modulation of the super surface light splitting and converging structure on the light can be ensured, and the light not corresponding to the color is avoided from being converged to the area where the sub-pixel is located.

[0153] Exemplarily, the period of the cylindrical nanorod in the red light modulation super surface light splitting and converging structure is 300 nanometers (nm), the period of the cylindrical nanorod in the blue light modulation super surface light splitting and converging structure is 200 nm, and the period of the cylindrical nanorod in the green light modulation super surface light splitting and converging structure is 250 nm. The height of the cylindrical nanorod in the vertical direction of the substrate is H = 850 nm. The radius of the cylindrical nanorod can be screened for the wavelengths of red light, green light and blue light, and a structure group that realizes 2π phase modulation can be constructed.

[0154] Exemplarily, the period of the super surface light splitting unit is 9 micrometers, which meets a set of RGB pixel sizes. The light is split for a set of RGB pixels, and the focal length is 25 micrometers (i.e., the thickness of the first orientation layer 56 in the liquid crystal box), which can better converge the light of the corresponding color and improve the display brightness.

[0155] Exemplarily, the wavelength of red light is 620 nm, the wavelength of green light is 532 nm, and the wavelength of blue light is 450 nm. The required deflection angles of RGB are -7°, 0° and 7°, respectively, to ensure that the RGB beams are separately controlled by the corresponding liquid crystal pixel switches after being separated.

[0156] In a specific implementation, according to the wavelengths of red light, green light and blue light, the period of the cylindrical nanorod and the phase, the red light modulation super surface light splitting and converging structure shown in FIG. 9A, the green light modulation super surface light splitting and converging structure shown in FIG. 9B and the blue light modulation super surface light splitting and converging structure shown in FIG. 9C can be obtained according to formula (3).

[0157] In order to use the super surface light splitting unit structure for phase expression, the phases corresponding to different colors of light are calculated by grid discretization according to the period of the super surface light splitting unit structure group, and the phases are folded by taking the remainder of 2π (i.e., the phase value is brought into the range of 0-2π). Then, the adjacent assignment conforming to the number of super surface unit structure groups is performed (for example, 8 phase covers 2π unit structure group, i.e., the phase after grid partition is brought into 1 / 4π, 1 / 2π, 3 / 4π, π, 5 / 4π, 3 / 2π, 7 / 4π and 2π), and finally expressed by the corresponding super surface unit structure.

[0158] Exemplarily, taking the center 4x4 region as an example, the structure coordinate distribution is shown in Table 1, the corresponding point phase value is shown in Table 2, and the corresponding nanorod structure radius is shown in Table 3.

[0159] Table 1: Center 4x4 unit structure coordinate values of a set of pixels corresponding to the super surface light splitting unit (unit: um)

[0160] Table 2: Center 4x4 unit structure phase values of a set of pixels corresponding to the super surface light splitting unit (unit: π)

[0161] Table 3: Super surface light splitting unit center 4x4 unit structure radius value corresponding to a group of pixels (unit: nm)

[0162] FIG. 10 is a plane schematic diagram of a super surface light splitting unit according to an exemplary embodiment of the present disclosure.

[0163] Exemplarily, according to the coordinate positions in Table 1, combined with formula (3), folding into the range of 2π, the phase values shown in Table 2 can be obtained. Further matching the unit structure of the super surface nanocolumn shown in FIG. 6A, so that the unit structure meets the phase modulation requirements of the RGB waveband under this condition, the structure radius of the super surface nanocolumn corresponding to the coordinate position is obtained as shown in Table 3. Finally, combined with the coordinate positions in Table 1 and the structure radius of the super surface nanocolumn in Table 3, the local structure arrangement schematic diagram of the super surface light splitting structure layer is obtained as shown in FIG. 10. It should be understood that this is only an exemplary embodiment of the present disclosure, not a limitation of the present disclosure.

[0164] In some embodiments, as shown in Table 1-Table 3 and FIG. 10, by determining the coordinate positions of the center of the super surface light splitting unit, combined with formula (3), the phase expression of different super surface light splitting units for light of different wavelengths can be calculated. Then only the diameter of the super surface nanocolumn (as shown in FIG. 10) can be adjusted, so as to adjust the phase expression of the super surface nanocolumn for light of different wavelengths, to realize the separation and focusing of light of different wavelengths, so that light of different colors can be separated and converged to the area where different subpixels are located.

[0165] In some embodiments, the position arrangement of different super surface nanocolumns can also be adjusted to realize the separation and convergence of light of different colors to the area where different subpixels are located. For example, as shown in FIG. 5, the plurality of super surface nanocolumns included in each super surface light splitting and converging structure are periodically arranged into a first region 30 with a non-rectangular contour; the plurality of first regions 30 included in each super surface light splitting unit can be spliced into a rectangular region. It should be understood that this is only an exemplary embodiment of the present disclosure, not a limitation of the present disclosure. FIG. 11A is a plane schematic diagram of a red light modulation super surface light splitting and converging structure included in a single super surface light splitting unit according to an exemplary embodiment of the present disclosure; FIG. 11B is a plane schematic diagram of a green light modulation super surface light splitting and converging structure included in a single super surface light splitting unit according to an exemplary embodiment of the present disclosure; FIG. 11C is a plane schematic diagram of a blue light modulation super surface light splitting and converging structure included in a single super surface light splitting unit according to an exemplary embodiment of the present disclosure.

[0166] In some embodiments, the first region 30 selected by the red light modulation metasurface light splitting and converging structure 501 can be the region labeled as 301 in FIG. 11A. The first region 30 selected by the green light modulation metasurface light splitting and converging structure 502 can be the region labeled as 302 in FIG. 11B. The first region 30 selected by the blue light modulation metasurface light splitting and converging structure 503 can be the region labeled as 303 in FIG. 11C. By splicing FIG. 11A, FIG. 11B, and FIG. 11C, the region of a metasurface light splitting unit as shown in FIG. 5 is formed, which can realize the separation of white light into red light, blue light, and green light.

[0167] It should be noted that FIG. 11A-FIG. 11C are only schematic illustrations of the arrangement of the metasurface light splitting unit and do not constitute a limitation on this disclosure.

[0168] The metasurface light splitting units in the metasurface light splitting structure layer in this disclosure can be designed according to the pixel size, pixel arrangement, and corresponding calculation and design of the structure, refractive index, and other parameters of the metasurface nanocolumns to ensure that the metasurface light splitting structure layer realizes the separation and focusing of white light, thereby meeting the corresponding display requirements. For example, the diameter of the metasurface nanocolumns at different coordinate positions (as shown in FIG. 10) can be adjusted to ensure that the metasurface light splitting structure layer realizes the separation and focusing of white light. The diameter and position of the metasurface nanocolumns (as shown in FIG. 5) can also be adjusted to ensure that the metasurface light splitting structure layer realizes the separation and focusing of white light. The height, diameter, and position of the metasurface nanocolumns can also be adjusted to ensure that the metasurface light splitting structure layer realizes the separation and focusing of white light. Various arrangement modes of the metasurface nanocolumns in the metasurface light splitting unit that can realize the separation and focusing of light of different colors are within the protection scope of this disclosure.

[0169] FIG. 12A-FIG. 12L are partial cross-sectional views of a display panel in a processing process according to an exemplary embodiment of the disclosure; and FIG. 13 is a processing flowchart of a display panel according to an exemplary embodiment of the disclosure.

[0170] Exemplarily, the embodiments of the disclosure also provide a preparation method of a display panel. In combination with FIG. 12A-FIG. 13, the preparation method of the display panel includes the following steps S01-S11.

[0171] In the S01 step, referring to FIG. 12A, a first substrate 51 is provided. For example, the first substrate can be a silicon-based substrate.

[0172] In the S02 step, referring to FIG. 12B, a reflective layer 54 is formed on the first substrate 51. For example, the material of the reflective layer can be aluminum.

[0173] In the S03 step, referring to FIG. 12C, a base portion 553 is formed on the side of the reflective layer 54 away from the first substrate 51. For example, the material of the base portion 553 can be silicon oxide.

[0174] In the S04 step, referring to FIG. 12D, a layer of super surface light splitting structure material 5510, a first mask layer 70, and an etching glue layer 80 are sequentially formed on the side of the base portion 553 away from the first substrate 51. For example, the material of the layer of super surface light splitting structure material 5510 can be titanium oxide, the material of the first mask layer 70 can be aluminum, and the material of the etching glue layer 80 can be ZEP500 or the like special glue for electron beam exposure.

[0175] In the S05 step, referring to FIG. 12E, a patterning process is performed on the etching glue layer 80 to form a pattern. For example, the pattern in the super surface light splitting structure layer can be processed on the etching glue layer by using an electron beam direct writing method.

[0176] In the S06 step, referring to FIG. 12F, an etching process is used to transfer the pattern on the etching glue layer 80 to the first mask layer 70, and then the etching glue layer 80 is removed. For example, a dry etching process can be used to transfer the pattern on the etching glue layer 80 to the first mask layer 70.

[0177] In the S07 step, referring to FIG. 12G, the etching process is continued to transfer the pattern on the first mask layer 70 to the layer of super surface light splitting structure material 5510, and then the first mask layer 70 is removed to obtain a plurality of super surface nano pillars 551.

[0178] In the S08 step, referring to FIG. 12H, a low refractive index glue material is filled in the gaps between the plurality of super surface nano pillars 551 as a filling layer 552 of the plurality of super surface structure units to form a super surface light splitting structure layer 55, thereby forming a first part P1 including the first substrate 51, the reflective layer 54, and the super surface light splitting structure layer 55.

[0179] The method further includes:

[0180] In the S09 step, referring to FIG. 12I, a second substrate 60 is provided.

[0181] In the S10 step, referring to FIG. 12J, a liquid crystal cell 530 is formed on the second substrate 60 to form a second part P2 including the second substrate 60 and the liquid crystal cell 530. The liquid crystal cell 530 can include a second alignment layer 58, a liquid crystal layer 57, and a first alignment layer 56. The second alignment layer 58 is located on the side of the liquid crystal layer 57 close to the second substrate 60, and the first alignment layer 56 is located on the side of the liquid crystal layer 57 away from the second substrate 60.

[0182] In step S11, referring to FIG. 12K, the first part P1 and the second part P2 are aligned and attached to form a display panel, for example, including an LCOS device.

[0183] Exemplarily, referring to FIG. 12L, in an embodiment of the present disclosure, the preparation method of the display panel can further include: forming a driving circuit layer 52 on the first substrate 51 before forming the reflective layer 54 on the first substrate; and forming a common electrode 59 on the second substrate 60 before forming the liquid crystal cell 530 on the second substrate 60.

[0184] FIG. 14 is a structural schematic diagram of a projection system according to some embodiments of the present disclosure.

[0185] Optionally, an embodiment of the present disclosure further provides a projection system 100. Referring to FIG. 14, the projection system can include the display panel 5 described above. By loading the pixel switch and the gray scale signal through the driving circuit layer and the common electrode above the liquid crystal cell, the display panel realizes the color separation conversion of the white light source to the RGB light, and finally outputs the color image signal. It should be understood that the projection system has the same beneficial effects as the display panel provided by the foregoing embodiments.

[0186] The projection system can further include a light source 1, a collimating lens 2, a polarizer 3, a polarization beam splitter 4, and a projection lens group 6.

[0187] Exemplarily, the light source 1 can be a white light source. For example, the light source 1 includes at least one of a white light LED light source, an RGB LED light source, or a laser diode light source. For example, the spectral band of the light source can contain the band of the mixed spectrum composed of various colors of light required by the projection system.

[0188] In some embodiments, the collimating lens 2 can collimate the light source to ensure that the subsequent projection light path has a divergence angle less than or equal to 20°. For example, the divergence angle of the outgoing light of the projection system is less than or equal to 20°.

[0189] In some embodiments, the polarizer 3 can polarize the light source to realize beam splitting and meet the liquid crystal control requirements.

[0190] In some embodiments, the polarization beam splitter 4 can realize the light path turning of the white light source and the modulated image information.

[0191] In some embodiments, the projection lens group 6 can realize the magnified imaging of the image information at a certain distance, so that the signal in the display panel is finally projected as the image size required by the viewer.

[0192] While some embodiments of the general inventive concept have been shown and described, it is to be understood that changes can be made in embodiments without departing from the principles and spirit of the general inventive concept, the scope of which is defined in the claims and their equivalents.

Claims

1. A display panel, characterized by, The display panel comprises: a first substrate; a second substrate arranged opposite to the first substrate; a liquid crystal layer arranged between the first substrate and the second substrate; a reflective layer arranged on a side of the first substrate facing the second substrate; and a metasurface light splitting structure layer arranged on a side of the reflective layer away from the first substrate, the metasurface light splitting structure layer comprising a plurality of metasurface light splitting units arranged periodically, at least one of the metasurface light splitting units comprising a plurality of metasurface light splitting converging structures, wherein the metasurface light splitting unit is configured to separate white light reflected by the reflective layer into a plurality of monochromatic lights, and converge the plurality of monochromatic lights to regions where a plurality of sub-pixels of the display panel are located respectively via the metasurface light splitting converging structures. A normal projection of the metasurface light splitting structure layer on the first substrate falls within a normal projection of the reflective layer on the first substrate.

2. The display panel of claim 1, wherein, The metasurface light splitting unit comprises a plurality of metasurface nanocolumns arranged periodically and a filling layer filled in gaps between the plurality of metasurface nanocolumns, wherein the metasurface nanocolumns are rotationally symmetric columnar structures.

3. The display panel of claim 1 or 2, wherein, wherein x and y are coordinate positions in a two-dimensional coordinate system constructed by a plane where the metasurface light splitting structure layer is located, λ is a wavelength of light, and f is a focal length of an equivalent lens of the metasurface light splitting structure layer; 4. The display panel of any one of claims 1-3, wherein, The metasurface light-splitting structure layer has a lens phase Ψ lens (x, y, f, λ), the lens phase Ψ lens (x, y, f, λ) satisfies equation (1): The display panel further comprises a first alignment layer between the metasurface light splitting structure layer and the liquid crystal layer, the first alignment layer having a first thickness, wherein the focal length f of the equivalent lens is equal to the first thickness. A refractive index of a material of the metasurface nanocolumns is greater than a refractive index of a material of the filling layer.

5. The display panel of claim 3, wherein, The refractive index of the material of the metasurface nanocolumns is greater than or equal to 1.5; and / or 6. The display panel of claim 3 or 5, wherein, The refractive index of the material of the filling layer is greater than or equal to 1 and less than or equal to 1.

3. wherein θ is an off-axis angle of a light beam with a wavelength of λ on an x-axis, wherein the x-axis is a transverse coordinate axis in a two-dimensional coordinate system constructed by a plane where the metasurface light splitting structure layer is located.

7. The display panel of any one of claims 1-6, wherein, The metasurface light splitting structure layer has a deflection phase Ψ d (x, y, λ), the deflection phase Ψ d (x, y, λ) satisfies equation (2): A normal projection of the metasurface nanocolumns on the first substrate has a first projection shape, the first projection shape being at least one of a circular shape, a square shape, or a rectangular shape.

8. The display panel of any of claims 3-7, wherein, In at least one of the metasurface light splitting units, the first projection shapes of the plurality of metasurface nanocolumns are not completely identical; and thicknesses of the plurality of metasurface nanocolumns in a light-out direction are identical.

9. The display panel of claim 8, wherein, In at least one of the metasurface light splitting units, the first projection shapes of the plurality of metasurface nanocolumns are identical; and the thicknesses of the plurality of metasurface nanocolumns in the light-out direction are not completely identical.

10. The display panel of claim 8, wherein, In at least one of the metasurface light splitting converging structures, a period of the metasurface nanocolumns is less than or equal to λ / 2, wherein λ is a wavelength range of light transmitted by the metasurface light splitting converging structure.

11. The display panel of any of claims 3-10, wherein, The metasurface light splitting structure layer further comprises a base portion, and the plurality of metasurface light splitting units are located on a side of the base portion away from the reflective layer.

12. The display panel of any one of claims 1-11, wherein, The material of the reflective layer comprises Al; and / or 13. The display panel of claim 12, wherein, The material of the base portion comprises SiO2; and / or The material of the metasurface nanocolumns comprises one of TiO2, SiNx, and GaNx. ​ 14. The display panel of any one of claims 1-13, wherein, The display panel further comprises a common electrode between the liquid crystal layer and the second substrate, a light shielding layer on the side of the reflective layer close to the first substrate, and a driving circuit layer on the side of the light shielding layer close to the first substrate.

15. A method for manufacturing a display panel, characterized by, Comprise: A first substrate is provided; A reflective layer is formed on the first substrate; A base portion is formed on the side of the reflective layer away from the first substrate; A layer of metasurface light splitting structure material, a first mask layer, and an etching adhesive layer are sequentially formed on the side of the base portion away from the first substrate; A patterning process is performed on the etching adhesive layer to form a pattern; An etching process is used to transfer the pattern on the etching adhesive layer to the first mask layer, and the etching adhesive layer is removed; An etching process is continued to transfer the pattern on the first mask layer to the layer of metasurface light splitting structure material, and the first mask layer is removed, resulting in a plurality of metasurface nano pillars; A gap between the plurality of metasurface nano pillars is filled with adhesive material as a filling layer of a plurality of metasurface structure units to form a metasurface light splitting structure layer, thereby forming a first part comprising the first substrate, the reflective layer, and the metasurface light splitting structure layer; The method further comprises: A second substrate is provided; A liquid crystal cell is formed on the second substrate to form a second part comprising the second substrate and the liquid crystal cell; The first part and the second part are aligned and bonded to form a display panel.

16. A projection system, characterized by The projection system comprises the display panel of any one of claims 1-14.

17. The projection system of claim 16, wherein, The projection system further comprises a light source, a collimating lens, a polarizer, a polarization beam splitter, and a projection lens group; The light emitted by the light source passes through the collimating lens, the polarizer, and the polarization beam splitter in sequence to enter the display panel to form incident light; The incident light is reflected, split, and focused by the display panel to form outgoing light; and The outgoing light passes through the polarization beam splitter and the projection lens group in sequence to form a projection image.

18. The projection system of claim 16 or 17, wherein, The divergence angle of the outgoing light of the projection system is less than or equal to 20°.

19. The projection system of claim 17, wherein, The light source comprises at least one of a white light LED light source, an RGB LED light source, or a laser diode light source.

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