Diffractive optical waveguide display device

Abstract

The present invention relates to the field of AR light guide display, specifically to a diffractive light guide display, which includes a diffraction grating, a waveguide sheet is installed on one side of the diffraction grating, and an image source is installed on the other side of the diffraction grating, and the light beam emitted by the image source passes through the diffraction grating and enters the waveguide sheet, and the diffraction grating includes periodically distributed liquid crystal microcapsules, the liquid crystal microcapsules are hollow spheres, with an inner diameter of 10-60 nm and a surface thickness of 5-30 nm, and the liquid crystal microcapsules are used to improve the diffraction efficiency of s-polarized light and p-polarized light, and allow both s-polarized light and p-polarized light to be totally reflected in the waveguide sheet, thereby improving the resolution of the image output by the waveguide sheet. The technology according to the present invention can intuitively, concretely and numerically improve the resolution of the image source, and also has advantages in aspects such as maximum brightness, resolution, ambient light contrast, energy consumption, service life, response speed and thermal stability.

Description

[Technical field]

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS This application claims priority to a Chinese patent application submitted to the China Patent Office on January 4, 2022, bearing application number 202210000607.4 and entitled "Diffractive Optical Waveguide Display Device", the entire contents of which are incorporated herein by reference.

[0002] The present invention relates to the field of AR light guide displays, and more particularly to diffractive light guide displays. [Background technology]

[0003] Optical waveguide display technology is an important development direction in the field of AR. Holographic gratings are usually manufactured by holographic exposure of photosensitive materials with coherent lasers, and have the advantages of high diffraction efficiency, low cost, and ease of mass production, so that the application of holographic gratings to optical waveguide AR display is expected. Polymer-dispersed liquid crystal holographic gratings are holographic gratings based on polymer / liquid crystal composite materials, which not only have excellent optical performance but also have electro-optical response, which has attracted widespread attention in the industry and has a high possibility of practical application in optical waveguide AR display. Meanwhile, micro-light-emitting diodes (Micro-LEDs) have advantages in maximum brightness, resolution, ambient light contrast, energy consumption, service life, response speed and thermal stability compared to liquid crystal displays (LCDs) and organic electroluminescence displays (OLEDs), and have already become the mainstream image source for AR display. In the future, the combination of polymer dispersed liquid crystal holographic grating, i.e. PDLC-VHG, and micron light emitting diodes is expected to become the mainstream technology scheme for AR optical waveguide display.

[0004] The ambient light contrast (ACR) of a diffractive optical waveguide display is a key performance parameter for display effect. Previous research has revealed that when ACR>3, the displayed image is relatively clear; when ACR>5, the image display effect satisfies people; and when ACR>10, a relatively noticeable display effect can be obtained (see Light-Sci.Appl.2021, 10, 216 for details). The calculation method of ACR is as follows: JPEG2025502003000002.jpg942, Here, L in and L AM are the input coupling light intensity and the ambient light intensity, respectively, and η in and η out are the diffraction efficiencies of the input and output coupling gratings, respectively, and T is the light transmittance of the waveguide lens. As can be seen from equation (1), the higher the diffraction efficiencies of the input and output coupling gratings, the higher the ACR and the better the display effect.

[0005] In FIG. 4, currently, conventional PDLC-VHG generally has a relatively high diffraction efficiency for only p-polarized light, and a relatively low diffraction efficiency for s-polarized light, because the liquid crystal molecules are generally aligned parallel to the lattice vector direction (see Mater. Chem.Front. 2017, 1, 294; Composites Part B 2020, 199, 108290), which causes that when PDLC-VHG is combined with an image source that emits non-polarized light, such as a micron light-emitting diode, only p-polarized light is combined and enters the optical waveguide sheet, and then further combined and exits to enter the human eye, while most s-polarized light is directly transmitted and wasted (FIG. 3), causing a relatively low ACR. Therefore, it is necessary to develop an optical waveguide display device that is not sensitive to the polarization direction of s light. Summary of the Invention [Problem to be solved by the invention]

[0006] The objective of the present invention is to provide a diffractive optical waveguide display device that can have relatively high diffraction efficiency for both s-polarized and p-polarized light emitted by an image source, and thus has relatively high ambient light contrast, thereby improving the resolution at the output end of the waveguide sheet. [Means for solving the problem]

[0007] In order to achieve the above object of the invention, the technical solutions adopted by the present invention are as follows.

[0008] The diffractive optical waveguide display device includes a diffraction grating, a waveguide sheet is provided on one side of the diffraction grating, and an image source is provided on the other side of the diffraction grating. A light beam emitted by the image source passes through the diffraction grating and enters the waveguide sheet. The diffraction grating includes periodically distributed liquid crystal microcapsules. The liquid crystal microcapsules are hollow spherical, have an inner diameter of 10 to 60 nm, and a surface thickness of 5 to 30 nm. The liquid crystal microcapsules are used to improve the diffraction efficiency for s-polarized light and p-polarized light, and to enable both s-polarized light and p-polarized light to be totally reflected within the waveguide sheet, thereby improving the resolution of an image output by the waveguide sheet.

[0009] Furthermore, the liquid crystal molecules in the liquid crystal microcapsules are all perpendicular to the surface of the liquid crystal microcapsules and are distributed in the circumferential direction of the liquid crystal microcapsules.

[0010] Furthermore, the orientations of the liquid crystal microcapsules are randomly distributed, and the liquid crystal molecule orientations in a single liquid crystal microcapsule are parallel to each other.

[0011] Furthermore, a plurality of liquid crystal microcapsule groups are arranged within the diffraction grating, a plurality of the liquid crystal microcapsules are arranged in parallel within the liquid crystal microcapsule groups, and the plurality of the liquid crystal microcapsule groups are arranged in parallel along the longitudinal direction of the diffraction grating.

[0012] Furthermore, the liquid crystal microcapsules in the liquid crystal microcapsule group are arranged so that the direction in which the liquid crystal microcapsules are arranged is inclined relative to the emission direction of the image source.

[0013] Furthermore, the diffraction grating further includes a transparent substrate, the liquid crystal microcapsules are disposed between two of the transparent substrates, a polymer is disposed between the two transparent substrates, and the image source enters from the transparent substrate on one side and exits from the transparent substrate on the other side, and enters into the waveguide sheet.

[0014] In addition, two diffraction gratings are provided, one at the input end and the other at the output end of the waveguide sheet, respectively, and the direction of the output light beam of the image source faces directly toward the input end of the waveguide sheet.

[0015] Moreover, the image source is a micron light emitting diode.

[0016] Furthermore, the improved resolution of the liquid crystal microcapsules is the ambient light contrast value.

[0017] Furthermore, the liquid crystal microcapsules include a shell layer material, the liquid crystal molecules are disposed within the shell layer material, and the shell layer material is formed by polymerization of an acrylate monomer. Effect of the Invention

[0018] The present invention has the following beneficial effects:

[0019] 1. In the case of using the PDLC-VHG manufactured by the conventional holographic photopolymerization induced phase separation method adopted in the prior art as a diffraction grating, the optical waveguide AR display device has a relatively high diffraction efficiency only for p-polarized light and a relatively low ambient light contrast, which causes low resolution. In contrast, the diffraction grating adopted in the present invention has a relatively high diffraction efficiency for both s-polarized light and p-polarized light emitted by the image source, thereby having a relatively high ambient light contrast and improving the resolution at the output end of the waveguide sheet.

[0020] 2. The diffraction grating of the present invention arranges the liquid crystal molecules perpendicular to the surface of the liquid crystal microcapsules and distributes them in the circumferential direction, or distributes the directions of multiple liquid crystal microcapsules randomly and the liquid crystal molecules in a single liquid crystal microcapsule are parallel to each other. Regardless of which method is used, there will always be an uncertain, disordered and random angle between the multiple liquid crystal molecules and the incident direction of the image source, so the diffraction grating of the present invention, i.e., PDLCC-VHG, is not sensitive to the polarization direction of light.

[0021] 3. By adopting Micro-LED as the image source, the present invention has advantages over LCD and OLED in terms of maximum brightness, resolution, ambient light contrast, energy consumption, service life, response speed and thermal stability.

[0022] 4. The present invention improves the resolution of the image source by improving the ambient light contrast value, and can intuitively, concretely and numerically improve the resolution of the image source. When actually produced and implemented, the ambient light contrast value can be specifically calculated, so as to estimate the resolution height of the display product in advance, and further, the display product can be classified and produced in advance according to the ambient light contrast value. [Brief description of the drawings]

[0023] [Figure 1] FIG. 1 is a schematic diagram of the overall structure of the present invention. [Diagram 2] FIG. 2 is a schematic diagram of a diffraction grating of the present invention. [Diagram 3] FIG. 1 is a schematic diagram of an optical waveguide display device according to the prior art; [Figure 4] FIG. 1 is a schematic diagram of a diffraction grating according to the prior art. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0024] The following clearly and completely describes the technical solutions in the embodiments of the present invention in conjunction with drawings 1 to 4 in the embodiments of the present invention, obviously, the described embodiments are only some of the embodiments of the present invention, not all of the embodiments. Unless otherwise specified, the technical means used in the embodiments are common means well known to those skilled in the art.

[0025] In describing the present invention, it should be understood that the orientations or positional relationships indicated by the terms "longitudinal", "lateral", "up", "down", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", etc. are orientations or positional relationships shown based on the drawings, and are merely for facilitating the description of the present invention, and do not indicate or imply that the devices or elements referred to have a particular orientation or must be configured and operated in a particular orientation, and should not be understood as limitations on the present invention.

[0026] As shown in FIG. 1, a diffractive optical waveguide display device includes a diffraction grating, a waveguide sheet is disposed on one side of the diffraction grating, and an image source is disposed on the other side of the diffraction grating. The light beam emitted by the image source passes through the diffraction grating and enters the waveguide sheet. The diffraction grating includes periodically distributed liquid crystal microcapsules, which are used to improve the diffraction efficiency for s-polarized light and p-polarized light and enable both s-polarized light and p-polarized light to be totally reflected within the waveguide sheet, thereby improving the resolution of the image output by the waveguide sheet.

[0027] Here, the waveguide sheet is a conventional technology used to transmit the image source. The light beam emitted by the image source first passes through the diffraction grating to enter the waveguide sheet. The diffraction grating is PDLCC-VHG, which is the specific name after the diffraction grating is improved in the present invention. After the light beam enters, it will diffract between the adjacent periodically distributed liquid crystal microcapsules, which will effectively diffract the s-polarized light and p-polarized light in the image source light beam. The image source light beam is then incident on the input end of the waveguide sheet at an inclined angle, and the image source light beam is totally reflected in the waveguide sheet and exits from the output end of the waveguide sheet. In the whole process, the diffraction grating effectively diffracts both the s-polarized light and the p-polarized light in the image source, thus avoiding the loss of the image source light beam exiting from the waveguide sheet caused by the s-polarized light directly passing through and directly hitting the waveguide sheet.

[0028] In contrast to the conventional holographic photopolymerization-induced phase separation method used in the prior art to manufacture PDLC-VHG as a diffraction grating, which has a relatively high diffraction efficiency for only p-polarized light and a relatively low ambient light contrast, ultimately resulting in low image resolution, the diffraction grating used in the present invention has a relatively high diffraction efficiency for both s-polarized light and p-polarized light emitted by the image source, thereby providing a relatively high ambient light contrast and improving the resolution at the output end of the waveguide sheet.

[0029] As shown in FIG. 4, in the prior art, PDLC-VHG is usually prepared by holographic photopolymerization induced phase separation method, so after the phase separation is completed, the liquid crystal molecules are generally oriented along the lattice vector direction, that is, along the direction parallel to the length of the lattice. The reasons why the liquid crystal molecules are oriented along the lattice vector direction are relatively complicated (see Annu. Rev. Mater. Sci. 2000, 30, 83), and the specific causes are as follows:

[0030] 1. The liquid crystal molecules are pressed into the anisotropic liquid crystal droplets, 2. The liquid crystal molecules are anchored perpendicular to the interface between the polymer and the liquid crystal; 3. The photopolymerization volume shrinks and presses the liquid crystal droplets.

[0031] In order to avoid the above factors causing the liquid crystal molecular orientation of the PDLCC-VHG adopted by the present invention to be the same as that in the PDLC-VHG, the present invention first coats the liquid crystal molecules with a shell layer material when manufacturing the PDLCC-VHG, so that the liquid crystal molecular orientation after coating is not affected by external factors, thereby avoiding alignment along the lattice vector direction after holographic exposure.

[0032] For the liquid crystal microcapsules adopted by the present invention, the liquid crystal molecular orientation manner includes, but is not limited to, the following manners:

[0033] In the first orientation mode, as shown in FIG. 2, the liquid crystal molecules in the liquid crystal microcapsules are all perpendicular to the surface of the liquid crystal microcapsule and distributed in the circumferential direction of the liquid crystal microcapsule, that is, the liquid crystal molecules are arranged in the radial direction of the liquid crystal microcapsule, the liquid crystal molecules are perpendicular to the orientation of the capsule wall, and the defect is located in the center of the liquid crystal microcapsule. Such a liquid crystal microcapsule has the same refractive index for light incident from all directions, and has relatively high diffraction efficiency for s-polarized light and p-polarized light.

[0034] The second orientation method is as follows: the orientations of multiple liquid crystal microcapsules are randomly and chaotically distributed, and the orientations of the liquid crystal molecules in a single liquid crystal microcapsule are parallel to each other, and in a single liquid crystal microcapsule, the liquid crystal molecules are aligned completely parallel to a certain direction, but the orientation of each liquid crystal microcapsule is also chaotic and random, so that macroscopically, all the liquid crystal microcapsules are still isotropic and still have relatively high diffraction efficiency for s-polarized light and p-polarized light.

[0035] Furthermore, a method can also be adopted in which multiple liquid crystal microcapsules and the liquid crystal molecules therein are all distributed in a completely random manner, that is, the liquid crystal molecules in a single liquid crystal microcapsule are distributed in a random and disordered manner, and the orientations of all the liquid crystal microcapsules are also distributed in a random and disordered manner relative to each other. Macroscopically, this method is the same in principle as the second method mentioned above, and still has isotropy and relatively high diffraction efficiency for s-polarized and p-polarized light.

[0036] No matter which of the above methods is adopted in the present invention, there will always be an uncertain, disorderly and random angle between the multiple liquid crystal molecules and the incident direction of the image source, so the diffraction grating in the present invention, i.e., PDLCC-VHG, is not sensitive to the polarization direction of light. Compared with the PDLC-VHG adopted in the prior art, the present invention greatly improves the diffraction efficiency for p-polarized light and s-polarized light.

[0037] When the PDLCC-VHG of the present invention is specifically prepared, the liquid crystal microcapsules are mixed with a photopolymerization monomer and a photoinitiator, and then a polymer dispersed liquid crystal microcapsule hologram grating, i.e., PDLCC-VHG, can be prepared by a holographic exposure method.

[0038] Specifically, the liquid crystal microcapsules include a shell layer material, liquid crystal molecules are placed in the shell layer material, and the shell layer material is formed by polymerization with an acrylate monomer. The liquid crystal microcapsules can be manufactured by an emulsion polymerization method, specifically, a thermal initiator, a monofunctional acrylate monomer and a polyfunctional acrylate monomer composition are used as shell layer material precursors, and liquid crystal is added. Then, a block copolymer is used as a surfactant to form an oil-in-water microemulsion using a phase transition temperature emulsification method, and the resulting mixture is further heated to polymerize the acrylate monomer into a shell layer, thereby producing and obtaining nano-sized liquid crystal microcapsules.

[0039] The arrangement of liquid crystal molecules in liquid crystal microcapsules can be controlled by changing the concentration of surfactant, the principle being that the surfactant is mainly distributed in the polymer shell layer, and can encourage the liquid crystal molecules to anchor vertically to the surface of the shell layer. For the liquid crystal microcapsules of the present invention, when the concentration of surfactant is lower than 2wt%, the liquid crystal molecules are distributed parallel to each other, and when the concentration of surfactant is 2wt% or more, the liquid crystal molecules are distributed in the circumferential direction, that is, forming the distribution of liquid crystal molecules in the present invention.

[0040] Specifically, the liquid crystal microcapsules adopt a hollow spherical structure and can generate effective diffraction in all directions for both p-polarized and s-polarized light from the image source. When specifically implemented, the waveguide sheet and the image source can be easily arranged, reducing the requirements for the angle and accuracy of the emitted light beam from the image source. The inner diameter is 10-60 nm, the surface thickness is 5-30 nm, and the shell layer material is a cross-linked polymer material or an inorganic material.

[0041] The liquid crystal in the liquid crystal microcapsules is nematic liquid crystal, and the commercialization mark is one of E7, THT-2, HH-02-1, HH-03-1, XEP-02-2, HH-04-4, HH-05-02, P36-9, P38-8, P36-204, P80-01, P42-1, and P92-1.

[0042] Furthermore, a plurality of liquid crystal microcapsule groups are arranged within the diffraction grating, a plurality of liquid crystal microcapsules arranged in parallel within the liquid crystal microcapsule groups, and the plurality of liquid crystal microcapsule groups are arranged in parallel along the longitudinal direction of the diffraction grating.

[0043] As shown in Figure 2, multiple liquid crystal microcapsule groups are arranged in parallel and periodically in the horizontal direction in the figure, i.e., along the longitudinal direction of the diffraction grating, with gaps between two adjacent liquid crystal microcapsule groups, and each individual liquid crystal microcapsule group contains multiple liquid crystal microcapsules arranged in parallel and periodically in the vertical direction in Figure 2.

[0044] Furthermore, the arrangement direction of the liquid crystal microcapsules in the liquid crystal microcapsule group and the emission direction of the image source are set to be inclined relative to each other.

[0045] Specifically, the image source light beam can be incident on the diffraction grating at an angle, and the alignment direction of the liquid crystal microcapsules in a single liquid crystal microcapsule group can be arranged in a structure in which it is inclined relative to the direction of the image source light beam.

[0046] Furthermore, the diffraction grating further includes a transparent substrate, the liquid crystal microcapsules are disposed between two transparent substrates, a polymer is disposed between the two transparent substrates, and an image source enters from the transparent substrate on one side and exits from the transparent substrate on the other side, and enters the waveguide sheet.

[0047] Specifically, the transparent substrate and the polymer are both conventional technologies, a light beam emitted by an image source can pass through the transparent substrate and the polymer, the total thickness of the diffraction grating is 2-50 μm, the period of the grating is 500 nm-10 μm, the refractive index of the polymer substrate is 1.40-1.60, and the ratio of the diffraction efficiency of the diffraction grating for p-polarized light and s-polarized light is 1.1:1.0-1.0:1.1.

[0048] In addition, two diffraction gratings are provided, one at the input end and the other at the output end of the waveguide sheet, respectively, such that the direction of the output light beam of the image source faces directly toward the input end of the waveguide sheet.

[0049] Specifically, the end of the emitted light beam of the image source that enters the waveguide sheet is the input end of the waveguide sheet, and the end away from the input end on the waveguide sheet is the output end.

[0050] As shown in FIG. 1, the specific layout of the entire structure of the present invention is as follows:

[0051] Two diffraction gratings, i.e., PDLCC-VHGs, are arranged at the incident end and exit end of the waveguide sheet, respectively, the waveguide sheet and the diffraction gratings are arranged in parallel, the two diffraction gratings are arranged in parallel and on the same side of the waveguide sheet, the multiple liquid crystal microcapsule groups in the diffraction grating are distributed along a direction parallel to the waveguide sheet, the liquid crystal microcapsules in a single liquid crystal microcapsule group are arranged at an incline relative to the light beam direction of the image source, and the light beam emission direction of the image source is perpendicular to the waveguide sheet.

[0052] In addition, the liquid crystal microcapsules in the two diffraction gratings are arranged symmetrically, so that the light beam of the image source can be effectively output at the output end of the waveguide sheet.

[0053] Furthermore, the image source is Micro-LED, and compared with LCD and OLED, Micro-LED displays have advantages in maximum brightness, resolution, ambient light contrast, energy consumption, service life, response speed and thermal stability, etc., and have become the mainstream image source for AR displays. The present invention can improve the resolution of the final output image regardless of whether any one of the above image sources or an image source not mentioned is adopted.

[0054] Furthermore, the improved resolution of the liquid crystal microcapsules is the ambient light contrast value.

[0055] The ambient light contrast value, i.e., ACR value, is closely related to the image display effect, and is also directly related to the diffraction efficiency of the input coupling grating and the output coupling grating. Therefore, by judging the imaging resolution of the image source through the ACR value, the imaging effect can be intuitively, specifically, and digitally judged. During actual production, the ACR value can be specifically calculated, so as to estimate the resolution of the display product in advance, and the display product can be pre-classified and pre-produced according to the ACR value.

[0056] The following is a detailed description of the diffraction grating of the present invention, i.e., PDLCC-VHG, through a specific comparison process of two experimental data. The specific notable advances achieved compared with the PDLC-VHG in the prior art are as follows:

[0057] Experimental Example: In this experimental example, the diffraction grating of the present invention, that is, PDLCC-VHG, was used.

[0058] The diffractive optical waveguide device included a Micro-LED image source, a PDLCC-VHG input coupling grating, a PDLCC-VHG output coupling grating and a waveguide sheet.

[0059] As shown in Figure 1, at the input end, the image displayed by the Micro-LED image source was input-coupled to the waveguide sheet by the PDLCC-VHG, and the brightness of the input-coupled light was 1200 nits. After undergoing total reflection within the waveguide sheet, the light was further output-coupled from the waveguide sheet by the PDLCC-VHG at the output end.

[0060] The thickness of the employed PDLCC-VHG was 10 μm, the period of the grating was 800 nm, the refractive index of the polymer substrate was 1.50, the inner diameter of the liquid crystal microcapsules was 30 nm, the thickness of the shell layer was 10 nm, the shell layer material was cross-linked polyacrylate, and the liquid crystal was THT-2.

[0061] The diffraction efficiencies of the PDLCC-VHG for s-polarized and p-polarized light were 88% and 89%, respectively.

[0062] Since the grating has different diffraction efficiencies for different polarizations, when calculating the ACR, Eq. It needs to be changed to JPEG2025502003000003.jpg962, Here, L ins and L inp are the luminance of s-polarized light and p-polarized light, respectively, and for a Micro-LED image source, L ins =L inpand η ins and η outs are the diffraction efficiencies for s-polarized light of the input and output coupling gratings, respectively, and η inp and η outp are the diffraction efficiencies for p-polarized light of the input- and output-coupling gratings.

[0063] Based on formula (2), when the ambient light luminance is 300 nits and the light transmittance of the light guide sheet is 90%, the ACR of this embodiment is 4.5, and the display effect is relatively clear.

[0064] Comparative Example: In this comparative example, a diffraction grating according to the prior art, that is, PDLC-VHG, was used.

[0065] The diffractive optical waveguide device included a Micro-LED image source, a PDLC-VHG input coupling grating, a PDLC-VHG output coupling grating and a waveguide sheet.

[0066] At the input end, the image displayed by the Micro-LED image source was input-coupled to the waveguide sheet by the PDLC-VHG, and the brightness of the input-coupled light was 1200 nits. After undergoing total reflection within the waveguide sheet, it was further output-coupled from the waveguide sheet by the PDLC-VHG at the output end.

[0067] The thickness of the employed PDLC-VHG was 10 μm, the period of the grating was 800 nm, the refractive index of the polymer substrate was 1.50, and the liquid crystal was E7.

[0068] The diffraction efficiency of the PDLC-VHG for s-polarized light and p-polarized light was 25% and 89%, respectively. Calculated based on formula (2), when the ambient light luminance was 300 nits and the light transmittance of the optical waveguide sheet was 90%, the ACR was 2.9, and the display effect did not reach the resolution standard.

[0069] As can be seen from the comparison between the above experimental examples and comparative examples, compared with the conventional technology, under the same image source, grating thickness, grating period, refractive index of the polymer substrate, type of liquid crystal, ambient light brightness, light transmittance of the optical waveguide sheet and other environmental factors, the ACR value of the final output image source of the present invention is much larger than the ACR value in the conventional technology, and is much clearer than the image output by the conventional technology. As can be seen from this, the diffraction grating in the present invention has significantly improved the resolution output by the image source.

[0070] Specifically, the complete working flow of the present invention is as follows:

[0071] As shown in Figures 1 and 2, for the emitted light beam of the Micro-LED image source, the light beam first enters the diffraction grating, i.e., PDLCC-VHG. When the s-polarized light and p-polarized light in the light beam pass through the diffraction grating, the light beam between two adjacent liquid crystal microcapsule groups will generate a diffraction effect, and the s-polarized light and p-polarized light will be incident into the input end of the waveguide sheet at an inclined angle, and will be totally reflected in the waveguide sheet, and finally output from the diffraction grating at the output end of the waveguide sheet. In the entire process, effective diffraction is generated for the s-polarized light and p-polarized light at the same time, which avoids the loss of s-polarized light and improves the resolution of the output image.

[0072] The above-described embodiments are merely intended to describe preferred modes of the present invention, and are not intended to limit the scope of the present invention. Any modifications, changes, alterations, and substitutions made by those skilled in the art to the technical solutions of the present invention without departing from the design spirit of the present invention should fall within the scope of protection determined by the claims of the present invention.

[0073] Finally, it should be explained that the above embodiments are only for explaining the technical solution of the present application, and are not limited thereto. Although the present application has been described in detail with reference to the above embodiments, those skilled in the art should understand that they may still make modifications to the technical solutions described in the above embodiments, or make equivalent replacements for some or all of the technical features therein, and these modifications or replacements do not depart from the essence of the corresponding technical solution within the scope of the technical solutions of the embodiments of the present application.

Claims

1. 1. A diffractive optical waveguide display device comprising a diffraction grating, a waveguide sheet disposed on one side of the diffraction grating, and an image source disposed on the other side of the diffraction grating, wherein a light beam emitted by the image source passes through the diffraction grating and enters the waveguide sheet, wherein the diffraction grating comprises periodically distributed liquid crystal microcapsules, each of which is a hollow sphere having an inner diameter of 10 to 60 nm and a surface thickness of 5 to 30 nm, and wherein the liquid crystal microcapsules are used to improve the diffraction efficiency for s-polarized light and p-polarized light, and to enable both s-polarized light and p-polarized light to be totally reflected within the waveguide sheet, thereby improving the resolution of an image output by the waveguide sheet.

2. 2. The diffractive optical waveguide display device according to claim 1, wherein the liquid crystal molecules in the liquid crystal microcapsules are all perpendicular to the surface of the liquid crystal microcapsules and are distributed in the circumferential direction of the liquid crystal microcapsules.

3. 2. The diffractive optical waveguide display device according to claim 1, wherein the orientations of the liquid crystal microcapsules are randomly distributed, and the orientations of the liquid crystal molecules in a single liquid crystal microcapsule are parallel to each other.

4. 2. The diffractive optical waveguide display device of claim 1, characterized in that a plurality of liquid crystal microcapsule groups are arranged within the diffraction grating, the plurality of liquid crystal microcapsule groups are arranged in parallel along the longitudinal direction of the diffraction grating, and a single liquid crystal microcapsule group includes a plurality of the liquid crystal microcapsules arranged in parallel.

5. 5. The diffractive optical waveguide display device according to claim 4, wherein the liquid crystal microcapsules are arranged in a direction in which the liquid crystal microcapsules are arranged and the direction in which the image source is emitted are inclined relative to each other.

6. 5. The diffractive optical waveguide display device of claim 4, wherein the diffraction grating further includes a transparent substrate, the liquid crystal microcapsules are disposed between two of the transparent substrates, a polymer is disposed between the two of the transparent substrates, and the image source enters from one side of the transparent substrate, exits from the other side of the transparent substrate, and enters into the waveguide sheet.

7. 2. The diffractive optical waveguide display device according to claim 1, wherein the diffraction grating is provided in two, one at the incident end and one at the exit end of the waveguide sheet, and the direction of the emitted light beam of the image source is directly opposite to the incident end of the waveguide sheet.

8. 2. The diffractive light guide display of claim 1 wherein said image source is a micron light emitting diode.

9. 2. The diffractive optical waveguide display of claim 1, wherein the improved resolution of the liquid crystal microcapsules is an ambient light contrast value.

10. 4. The diffractive optical waveguide display device according to claim 2 or 3, characterized in that the liquid crystal microcapsules contain a shell layer material, the liquid crystal molecules are placed within the shell layer material, and the shell layer material is formed by polymerization of an acrylate-based monomer.

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