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 filed with 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 belongs to the field of AR optical waveguide displays, and specifically relates to diffractive optical waveguide displays. [Background technology]

[0003] Optical waveguide display technology is an important development direction in the field of AR. Holographic gratings are typically fabricated by holographically exposing a photosensitive material using a coherent laser. Due to their advantages of high diffraction efficiency, low cost, and ease of mass production, holographic grating-based optical waveguide AR displays are expected to be applied. Polymer-dispersed liquid crystal holographic gratings are holographic gratings based on polymer / liquid crystal composite materials. They not only offer excellent optical performance but also electro-optical response. They have attracted widespread attention in the industry and are expected to be widely used in optical waveguide AR displays. Meanwhile, micro-LEDs (micro-LEDs) have advantages over liquid crystal displays (LCDs) and organic electroluminescent displays (OLEDs) in terms of maximum brightness, resolution, ambient light contrast, energy consumption, service life, response speed, and thermal stability, and have already become the mainstream image source for AR displays. 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 proposal for AR optical waveguide displays.

[0004] The ambient light contrast (ACR) of a diffractive optical waveguide display is a key performance parameter for display effect. Previous research has shown that when ACR>3, the displayed image is relatively clear; when ACR>5, the image display effect is satisfying; and when ACR>10, a relatively noticeable display effect can be obtained (see Light-Sci.Appl.2021, 10, 216 for details). The calculation method for ACR is as follows: JPEG0007763544000001.jpg942, where 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] As shown in Figure 4, conventional PDLC-VHGs generally have relatively high diffraction efficiency for p-polarized light but relatively low diffraction efficiency for s-polarized light. This is because the liquid crystal molecules are generally aligned parallel to the lattice vector (see Mater. Chem. Front. 2017, 1, 294; Composites Part B 2020, 199, 108290). This means that when a PDLC-VHG is combined with an image source that emits unpolarized light, such as a micron light-emitting diode, only p-polarized light is coupled into the optical waveguide sheet and then further coupled out and enters the human eye. Most s-polarized light is directly transmitted and wasted (Figure 3), resulting in a relatively low ACR. Therefore, there is a need 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 therefore 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 disposed on one side of the diffraction grating, and an image source 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. 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 improve the diffraction efficiency for s-polarized light and p-polarized light, enabling 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.

[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 orientations of the liquid crystal molecules in a single liquid crystal microcapsule are parallel to each other.

[0011] Furthermore, a plurality of groups of liquid crystal microcapsules are arranged within the diffraction grating, and a plurality of the liquid crystal microcapsules are arranged in parallel within the group of liquid crystal microcapsules, and the plurality of groups of liquid crystal microcapsules 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 and the direction in which the image source is emitted are inclined relative to each other.

[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 one side of the transparent substrate, exits from the other side of the transparent substrate, and enters the waveguide sheet.

[0014] Furthermore, two diffraction gratings are provided, one at the incident end and the other at the exit end of the waveguide sheet, and the direction of the emitted light beam from the image source faces the incident end of the waveguide sheet.

[0015] Furthermore, 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 polymerizing an acrylate-based monomer. [Effects of the Invention]

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

[0019] 1. In the case of using PDLC-VHG manufactured by the conventional holographic photopolymerization-induced phase separation method as a diffraction grating in the prior art, the resulting optical waveguide AR display device has a relatively high diffraction efficiency only for p-polarized light and a relatively low ambient light contrast, resulting in low resolution. In contrast, the diffraction grating used in the present invention has a relatively high diffraction efficiency for both s-polarized and p-polarized light emitted by the image source, resulting in 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 the orientation of multiple liquid crystal microcapsules is randomly distributed, and the orientation of the liquid crystal molecules in a single liquid crystal microcapsule is parallel to each other. Regardless of which method is used, the angle between the multiple liquid crystal molecules and the incident direction of the image source will always be uncertain, disordered, and random. Therefore, 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 producing and implementing, the ambient light contrast value can be specifically calculated, thereby pre-estimating the resolution height of the display product, and further pre-classifying and pre-producing the display product based on the ambient light contrast value. [Brief explanation of the drawings]

[0023] [Figure 1] 1 is a schematic diagram of the overall structure of the present invention; [Figure 2] 1 is a schematic diagram of a diffraction grating of the present invention. [Figure 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 INVENTION

[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, and it is obvious that the described embodiments are only some embodiments of the present invention, and not all embodiments. Unless otherwise specified, the technical means used in the embodiments are conventional 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," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," etc. are orientations or positional relationships shown based on the drawings, and are intended merely to facilitate the description of the present invention, and do not indicate or imply that the referred-to devices or elements must have a particular orientation or be configured and operated in a particular orientation, and therefore should not be understood as limitations on the present invention.

[0026] As shown in Figure 1, a diffractive optical waveguide display device 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. 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. The liquid crystal microcapsules 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 a diffraction grating to enter the waveguide sheet. The diffraction grating is a PDLCC-VHG, which is a specific name for the improved diffraction grating used in the present invention. After the light beam enters, it is diffracted between the adjacent periodically distributed liquid crystal microcapsules, thereby generating effective diffraction for the s-polarized 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 oblique angle, whereupon the image source light beam is totally reflected within the waveguide sheet and emerges from the output end of the waveguide sheet. In the entire process, the diffraction grating effectively diffracts both the s-polarized and p-polarized light in the image source, thereby avoiding the loss of the image source light beam emitted from the waveguide sheet due to the s-polarized light directly passing through or directly incident on the waveguide sheet.

[0028] In the case of using a PDLC-VHG manufactured by the conventional holographic photopolymerization-induced phase separation method as a diffraction grating in the prior art, the resulting optical waveguide AR display device has a relatively high diffraction efficiency only for p-polarized light and a relatively low ambient light contrast, ultimately resulting in low image resolution. In contrast, the diffraction grating employed in the present invention has a relatively high diffraction efficiency for both s-polarized and p-polarized light emitted by the image source, resulting in a relatively high ambient light contrast and improving the resolution at the output end of the waveguide sheet.

[0029] As shown in Figure 4, in conventional PDLC-VHGs, which are usually produced by holographic photopolymerization-induced phase separation, after phase separation is complete, the liquid crystal molecules generally align along the lattice vector, i.e., along the direction parallel to the length of the lattice. The reasons for the alignment of the liquid crystal molecules along the lattice vector are relatively complex (see Annu. Rev. Mater. Sci. 2000, 30, 83). The specific causes are as follows:

[0030] 1. The liquid crystal molecules are pressed into 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 of 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 preventing the liquid crystal molecules from being aligned along the grating vector direction after holographic exposure.

[0032] For the liquid crystal microcapsules adopted by the present invention, the liquid crystal molecular alignment methods include, but are not limited to, the following methods:

[0033] In the first orientation mode, as shown in Figure 2, the liquid crystal molecules in the liquid crystal microcapsules are all perpendicular to the surface of the liquid crystal microcapsules and are distributed circumferentially around the liquid crystal microcapsules, i.e., the liquid crystal molecules are arranged radially around the liquid crystal microcapsules, the liquid crystal molecules are perpendicular to the orientation of the capsule wall, and the defects are located at the center of the liquid crystal microcapsules. Such liquid crystal microcapsules have the same refractive index for light incident from all directions and have relatively high diffraction efficiency for s-polarized and p-polarized light.

[0034] The second orientation method is as follows: the orientations of multiple liquid crystal microcapsules are randomly and disorderly distributed relative to each other, while 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 perfectly parallel to a certain direction, but the orientation of each liquid crystal microcapsule is also random and disordered, so macroscopically, all the liquid crystal microcapsules are still isotropic and still have relatively high diffraction efficiency for s-polarized 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 disordered manner, that is, the liquid crystal molecules in a single liquid crystal microcapsule are distributed in a disordered and random manner, and the orientations of all the liquid crystal microcapsules are also distributed in a disordered and random 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, the angle between the liquid crystal molecules and the incident direction of the image source will always be uncertain, disordered, and random. Therefore, 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] Specifically, the PDLCC-VHG of the present invention can be prepared by mixing the liquid crystal microcapsules with a photopolymerizable monomer and a photoinitiator, followed by holographic exposure to produce a polymer dispersed liquid crystal microcapsule holographic grating, i.e., PDLCC-VHG.

[0038] Specifically, the liquid crystal microcapsules contain a shell layer material, and liquid crystal molecules are placed within the shell layer material. The shell layer material is formed by polymerizing an acrylate monomer. The liquid crystal microcapsules can be produced 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. The resulting mixture is then heated to polymerize the acrylate monomer into a shell layer, thereby producing nano-sized liquid crystal microcapsules.

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

[0040] Specifically, the liquid crystal microcapsules have a hollow spherical structure, which can effectively diffract both p-polarized and s-polarized light from the image source in all directions. When specifically implemented, the waveguide sheet and image source can be easily positioned, reducing the requirements for the angle and accuracy of the emitted light beam from the image source. The inner diameter is 10 to 60 nm, the surface thickness is 5 to 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, and a plurality of liquid crystal microcapsules arranged in parallel within the liquid crystal microcapsule groups are arranged in parallel along the longitudinal direction of the diffraction grating.

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

[0044] 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 and the direction in which the image source is emitted are 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 set in a structure 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 one side of the transparent substrate, exits from the other side of the transparent substrate, and enters the waveguide sheet.

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

[0048] Furthermore, two diffraction gratings are provided, one at the incident end and the other at the exit end of the waveguide sheet, so that the direction of the emitted light beam from the image source faces the incident 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 incident end of the waveguide sheet, and the end that is away from the incident end on the waveguide sheet is the exit end.

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

[0051] Two diffraction gratings, i.e., PDLCC-VHG, are arranged at the incident end and the exit end of the waveguide sheet, respectively. The waveguide sheet and the diffraction grating are arranged parallel to each other, and the two diffraction gratings are arranged side by side 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, and the liquid crystal microcapsules in a single liquid crystal microcapsule group are arranged at an inclination 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 a Micro-LED, which has advantages over LCD and OLED in terms of maximum brightness, resolution, ambient light contrast, energy consumption, service life, response speed, thermal stability, etc., and has already become the mainstream image source for AR displays. The present invention can improve the resolution of the final output image, regardless of whether any of the above image sources or an image source not mentioned is used.

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

[0055] The ambient light contrast value, or ACR value, is closely related to the image display effect, and is also directly related to the diffraction efficiency of the input and output coupling gratings. Therefore, by determining the imaging resolution of the image source using the ACR value, the imaging effect can be intuitively, specifically, and digitally determined. When actually producing, the ACR value can be specifically calculated, which allows the resolution level of the display product to be estimated in advance, and the display product can be pre-classified and pre-produced based on the ACR value.

[0056] The following will specifically explain the diffraction grating of the present invention, i.e., PDLCC-VHG, through a specific comparison process of two experimental data, and the specific significant improvements 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, the image displayed by the micro-LED image source was input-coupled to the waveguide sheet by the PDLCC-VHG at the input end, and the brightness of the input-coupled light was 1200 nits. After undergoing total reflection within the waveguide sheet, the PDLCC-VHG was further used at the output end to output the light from the waveguide sheet.

[0060] The thickness of the PDLCC-VHG employed was 10 μm, the grating period 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 JPEG0007763544000002.jpg962, where L ins and L inp are the s- and p-polarized light intensities, respectively, and for a Micro-LED image source, L ins =L inpand η ins and η outs are the diffraction efficiencies of the input and output coupling gratings for s-polarized light, 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 optical waveguide sheet is 90%, the ACR of this example 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, the light was output 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 efficiencies of the PDLC-VHG for s-polarized and p-polarized light were 25% and 89%, respectively. Calculated based on equation (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 meet 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 significantly improves the resolution output by the image source.

[0070] The specific complete working flow of the present invention is as follows:

[0071] As shown in Figures 1 and 2, for the light beam emitted from the Micro-LED image source, the light beam first enters the diffraction grating, i.e., PDLCC-VHG. When the s-polarized and p-polarized light in the light beam passes through the diffraction grating, the light beam between two adjacent liquid crystal microcapsule groups will generate a diffraction effect, and the s-polarized and p-polarized light will then enter the input end of the waveguide sheet at an inclined angle, undergo total reflection within 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 simultaneously generated for the s-polarized and p-polarized light, avoiding the loss of s-polarized light and improving 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, or 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 noted that the above embodiments are only for illustrating the technical solutions of the present application, and are not intended to limit the same. 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 substitutions for some or all of the technical features therein, and such modifications or substitutions will not depart from the essence of the corresponding technical solutions within the scope of the technical solutions of the embodiments of the present application.

Claims

1. A diffractive optical waveguide display device including a diffraction grating, a waveguide sheet disposed on one side of the diffraction grating, an image source disposed on the other side of the diffraction grating, and a light beam emitted by the image source passing through the diffraction grating and entering the waveguide sheet, the diffraction grating comprises a plurality of periodically distributed liquid crystal microcapsules, each of which is hollow spherical, has 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 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; A diffractive optical waveguide display device, characterized in that 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.

2. A diffractive optical waveguide display device including 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 includes a plurality of periodically distributed liquid crystal microcapsules, each of which is hollow spherical and has an inner diameter of 10 to 60 nm and a surface thickness of 5 to 30 nm, and 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, A diffractive optical waveguide display device, characterized in that the liquid crystal molecules in a single liquid crystal microcapsule are oriented parallel to a predetermined orientation direction, and the orientation direction of the liquid crystal molecules is random in multiple liquid crystal microcapsules.

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

4. 4. The diffractive optical waveguide display device according to claim 3, wherein the direction in which the liquid crystal microcapsules in the liquid crystal microcapsule group are arranged is inclined relative to the direction in which the image source is emitted.

5. 4. The diffractive optical waveguide display device of claim 3, wherein the diffraction grating further comprises 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 one side of the transparent substrate, exits from the other side of the transparent substrate, and enters into the waveguide sheet.

6. 2. The diffractive optical waveguide display device according to claim 1, wherein two diffraction gratings are installed, 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 facing the incident end of the waveguide sheet.

7. 2. A diffractive optical waveguide display as claimed in claim 1, wherein said image source is a micron light emitting diode.

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

9. 3. The diffractive optical waveguide display device according to claim 1, wherein the liquid crystal microcapsules contain 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-based monomer.

Images