WO2022052949A1

WO2022052949A1 - Optical waveguide assembly and display device comprising optical waveguide assembly

Info

Publication number: WO2022052949A1
Application number: PCT/CN2021/117164
Authority: WO
Inventors: 赵瑜; 马珂奇
Original assignee: 宁波舜宇光电信息有限公司
Priority date: 2020-09-11
Filing date: 2021-09-08
Publication date: 2022-03-17
Also published as: CN114167606B; CN116194819A; CN114167606A

Abstract

An optical waveguide assembly, comprising: a waveguide sheet (1) and at least two diffraction units. A first diffraction unit (2) comprises a first in-coupling liquid crystal grating (21) and a first out-coupling liquid crystal grating (22), the first in-coupling liquid crystal grating (21) being used for coupling a first light into the waveguide sheet (1), and the first out-coupling liquid crystal grating (22) being used for coupling the first light out of the waveguide sheet (1). A second diffraction unit (3) comprises a second in-coupling liquid crystal grating (31) and a second out-coupling liquid crystal grating (32), the second in-coupling liquid crystal grating (31) being used for coupling a second light into the waveguide sheet (1), and the second out-coupling liquid crystal grating (32) being used for coupling the second light out of the waveguide sheet (1). By alternately applying a voltage to the diffraction units, the first in-coupling liquid crystal grating (21) and the first out-coupling liquid crystal grating (22) of the first diffraction unit (2) or the second in-coupling liquid crystal grating (31) and the second out-coupling liquid crystal grating (32) of the second diffraction unit (3) are in a grating state in the first direction, so that light of different wavelengths may be respectively diffracted, so as to achieve a full-color display and a simple, lightweight, and small structure.

Description

Optical waveguide assembly and display device including the same

technical field

The present application relates to the technical field of optical transmission, and in particular, to an optical waveguide assembly and a display device including the optical waveguide assembly.

Background technique

Display devices are mainly used to display pictures or videos to human eyes, and display devices can be widely used in fields such as virtual reality, augmented reality, mixed reality or military.

The display device includes an optical waveguide sheet and an image source. The image source inputs light into the waveguide sheet, and then enters the human eye through diffraction to form a visual aberration, thereby forming a 3D effect. In order to give users a better visual experience, the display device needs a full-color display.

However, the transmission efficiency and diffraction angle of the single-layer waveguide sheet for different wavelengths of light are different, which usually causes the proportion and exit angle of the three colors of red, green and blue to be out of balance after transmission, resulting in uneven color and display color cast. and rainbow effect.

At present, for full-color display, a structure of stacking multilayer waveguide sheets is generally used, and each layer of waveguide sheets is used to modulate light in a specific wavelength range. For example, in the structure of stacking two layers of waveguide sheets, one layer is used to process the light of the blue light field and part of the green light field, and the other layer is used to process the light of part of the green light field and all the red light field; Layered waveguide sheet stacking structure, three-layer waveguide sheets are used to process the light of the blue light, red light, and green light field of view respectively.

However, such a structure of stacking waveguide sheets will lead to a larger overall thickness of the display device, which is not conducive to the miniaturization and weight reduction of the device.

SUMMARY OF THE INVENTION

The main purpose of the present application is to provide an optical waveguide assembly capable of full-color display with a simple structure and a display device including the optical waveguide assembly.

An embodiment of the present application provides an optical waveguide assembly, including:

a waveguide sheet, comprising a first optical surface and a second optical surface opposite to the first optical surface, and the waveguide sheet is used for total reflection transmission of light therein; and

at least two diffractive units, where

- the first diffractive unit comprises a first in-coupled liquid crystal grating and a first out-coupled liquid crystal grating provided on the first optical surface, the first in-coupled liquid crystal grating and the first out-coupled liquid crystal grating are arranged to be applied When a voltage or no voltage is applied, it is in a grating state in the first direction, and the first coupled-in liquid crystal grating is used to couple the first light into the waveguide sheet under the condition of being in a grating state in the first direction, so The first out-coupling liquid crystal grating is used to couple the first light out of the waveguide sheet to the visible area under the condition that the first direction is in a grating state, and

- a second diffractive unit comprising a second in-coupled liquid crystal grating and a second out-coupled liquid crystal grating provided on the second optical surface, the second in-coupled liquid crystal grating and the second out-coupled liquid crystal grating being arranged to be applied When a voltage or no voltage is applied, it is in a grating state in the first direction, and the second coupled-in liquid crystal grating is used to couple the second light into the waveguide sheet when the second light is in a grating state in the first direction, so The second out-coupling liquid crystal grating is used to couple the second light out of the waveguide sheet to the visible area under the condition of the grating state in the first direction, and the wavelength of the second light is the same as the wavelength of the first light different;

Wherein, by alternately applying voltages to each diffraction unit, the first coupling-in liquid crystal grating and the first coupling-out liquid crystal grating of the first diffractive unit or the second coupling-in liquid crystal grating and the second coupling-out of the second diffractive unit The outgoing liquid crystal grating is in a grating state in the first direction, so that the first light rays and the second light rays with different wavelengths can be diffracted respectively.

In one embodiment, the period of the first coupled-in liquid crystal grating and the first coupled-out liquid crystal grating is set to correspond to the wavelength of the first light;

The period of the second coupled-in liquid crystal grating and the second coupled-out liquid crystal grating is set to correspond to the wavelength of the second light.

In one embodiment, the first light is blue light and a part of green light with a wavelength close to the blue light, and the second light is red light and another part of green light with a wavelength close to the red light.

In one embodiment, the first in-coupled liquid crystal grating, the first out-coupled liquid crystal grating, the second in-coupled liquid crystal grating and the second out-coupled liquid crystal grating are arranged to be in the first A grating state in the direction, and a uniform dielectric state in the first direction when no voltage is applied.

In one embodiment, the first direction is parallel to the first optical surface or the second optical surface of the waveguide sheet, the first coupled-in liquid crystal grating, the first coupled-out liquid crystal grating, the first The two coupled-in liquid crystal gratings and the second coupled-out liquid crystal gratings are in a one-dimensional grating state in the first direction when a voltage is applied.

In one embodiment, the first coupled-in liquid crystal grating, the first coupled-out liquid crystal grating, the second coupled-in liquid crystal grating, and the second coupled-out liquid crystal grating respectively comprise:

The liquid crystal layer includes a plurality of liquid crystals, and the liquid crystals are cholesteric liquid crystals;

two alignment film layers, the two alignment film layers are arranged on both sides of the liquid crystal layer opposite to each other and are used to give the initial director of the liquid crystal;

a first electrode layer; and

For the second electrode layer, the first electrode layer and the second electrode layer are disposed on the outside of the two alignment film layers opposite to each other.

In one embodiment, the liquid crystal pitch of the first coupled-in liquid crystal grating and the first coupled-out liquid crystal grating is 340 nm.

In one embodiment, the liquid crystal pitch of the second coupled-in liquid crystal grating and the second coupled-out liquid crystal grating is 440 nm.

In one embodiment, the thickness of the liquid crystal layer does not exceed 2.5 times the liquid crystal pitch.

In one embodiment, the voltage applied to the first coupled-in liquid crystal grating, the first coupled-out liquid crystal grating, the second coupled-in liquid crystal grating and the second coupled-out liquid crystal grating is a square wave of 1KHz Alternating current, the voltage amplitude is 5V ~ 22V.

In one embodiment, the first electrode layer and the second electrode layer are made of indium tin oxide (ITO) material.

In one embodiment, the first coupled-in liquid crystal grating, the first coupled-out liquid crystal grating, the second coupled-in liquid crystal grating, and the second coupled-out liquid crystal grating further comprise a plurality of spacers, respectively, so The plurality of spacers are distributed between the two alignment film layers to support the two alignment film layers and maintain and determine the distance therebetween.

In one embodiment, the waveguide sheet constitutes a substrate of a liquid crystal grating, the first coupled-in liquid crystal grating, the first coupled-out liquid crystal grating, the second coupled-in liquid crystal grating, and the second coupled-out liquid crystal grating Each of the gratings further includes a protective layer, and the substrate and the protective layer are disposed on the outer sides of the first electrode layer and the second electrode layer opposite to each other.

In one embodiment, the protective layer is made of glass material and has a thickness of 0.1 mm˜0.3 mm.

In one embodiment, the thickness of the waveguide sheet is 0.3-2.5 mm, and the refractive index is 1.4-2.2.

In one embodiment, the optical waveguide assembly further includes a third diffractive unit, the third diffractive unit includes a third coupled-in liquid crystal grating and a third coupled-out liquid crystal grating, the third coupled-in liquid crystal grating is provided on the first An in-coupling liquid crystal grating is disposed on a surface opposite to the waveguide sheet or on a surface of the second coupling-in liquid crystal grating opposite to the waveguide sheet, and the third out-coupling liquid crystal grating is disposed on the The first out-coupling liquid crystal grating is disposed on a surface opposite to the waveguide sheet or on a surface opposite the second out-coupling liquid crystal grating and the waveguide sheet, and the third coupling-in liquid crystal grating and The third out-coupled liquid crystal grating is set to be in a grating state in the first direction when a voltage is applied or no voltage is applied;

The third coupled-in liquid crystal grating is used for coupling the third light into the waveguide sheet when the grating state is in the first direction, and the third coupled-out liquid crystal grating is used for coupling the third light into the waveguide sheet in the first direction In the case of the grating state, the third light is coupled out of the waveguide sheet to the visible area, and the wavelength of the third light is different from that of the first light and the second light,

Wherein, by alternately applying voltages to each diffraction unit, the first coupling-in liquid crystal grating and the first coupling-out liquid crystal grating of the first diffractive unit or the second coupling-in liquid crystal grating and the second coupling-out of the second diffractive unit The output liquid crystal grating or the third coupled-in liquid crystal grating and the third coupled-out liquid crystal grating of the third diffraction unit are in the grating state in the first direction, so that the first light, the second light and the third light with different wavelengths can be diffracted respectively. light.

An embodiment of the present application also provides a display device, including:

A light projector, the light projector includes a display chip and a projection lens, the display chip is used to control at least a first light ray and a second light ray that output a display image at a certain frequency and in a time sequence, and the projection lens is used to project the the light output by the display core; and

An optical waveguide assembly, the optical waveguide assembly is the optical waveguide assembly described in any of the above embodiments, at least the first of the first diffraction unit of the optical waveguide assembly is coupled into the liquid crystal grating and the second of the second diffraction unit The coupling-in liquid crystal grating is used for coupling the light projected by the projection lens into the waveguide sheet of the optical waveguide assembly, and at least the first coupling-out liquid crystal grating and the second out-coupling liquid crystal grating of the first diffraction unit of the optical waveguide assembly The second out-coupling liquid crystal grating of the diffractive unit is used to couple the light coupled into the waveguide sheet out of the waveguide sheet to the visible area,

By alternately applying voltage to each diffractive unit, the optical waveguide assembly is controlled at the same frequency as the output of the first light and the second light, so that the grating of the first diffractive unit or the second diffractive unit is in the first diffractive unit correspondingly. The direction is in a grating state to diffract the first light rays and the second light rays with different wavelengths respectively.

In one embodiment, the first coupling-in liquid crystal grating, the first coupling-out liquid crystal grating of the first diffraction unit and the second coupling-in liquid crystal grating and the second out-coupling liquid crystal grating of the second diffractive unit are applied respectively. The corresponding periodic voltage is used to control and switch the first coupled-in liquid crystal grating, the first coupled-out liquid crystal grating of the first diffraction unit, and the second coupled-in liquid crystal grating and the second coupled-out liquid crystal grating of the second diffractive unit. The grating state is in the first direction.

In one embodiment, the frequency at which the display chip outputs the first light and the second light is 60 Hz.

Beneficial effects:

In the optical waveguide assembly provided by the present application, a diffraction unit is provided on each of the two surfaces of the waveguide sheet, and each diffraction unit includes an in-coupling liquid crystal grating and an out-coupling liquid crystal grating respectively, and the in-coupling liquid crystal grating and the out-coupling liquid crystal grating are arranged at When the voltage is applied or not, it is in the grating state in the first direction, and each grating of the first diffraction unit and the second diffraction unit is made by whether to apply a voltage to the coupled-in liquid crystal grating and the coupled-out liquid crystal grating of the corresponding diffraction unit. It is in a grating state in the first direction, thereby diffracting light with different wavelengths (lights with different colors have different wavelengths), and the optical waveguide assembly provided in this embodiment only needs a single-layer waveguide sheet to achieve full-color display. Simple, thin, compact, easy to control, and easy to manufacture. In addition, in the optical waveguide assembly provided in this embodiment, when only a single-layer waveguide sheet is used, light of different wavelengths is diffracted by different gratings, thereby ensuring a certain diffraction angle of light of different wavelengths, improving the diffraction efficiency and avoiding the Color casts, chromatic dispersion, color unevenness, and rainbow effects. Moreover, the first coupled-in liquid crystal grating, the first coupled-out liquid crystal grating, the second coupled-in liquid crystal grating, and the second coupled-out liquid crystal grating of the optical waveguide assembly provided in this embodiment are equivalent to ordinary one-dimensional surface relief gratings. Therefore, the field of view The angular range is mainly affected by the refractive index of the waveguide sheet itself, and it can have the field angle range that the ordinary surface relief grating waveguide sheet can achieve, and the field angle is large.

Description of drawings

The advantages of the above and/or additional aspects of the present invention will become apparent and readily understood from the following description of embodiments in conjunction with the accompanying drawings, wherein:

FIG. 1 is a schematic structural diagram of an optical waveguide assembly provided by an embodiment of the present application;

FIG. 2 is a schematic structural diagram of a liquid crystal grating of an optical waveguide assembly according to an embodiment of the present application;

3 is a schematic diagram of a working state of a liquid crystal grating of an optical waveguide assembly according to an embodiment of the present application;

4 is a schematic diagram of another working state of the liquid crystal grating of the optical waveguide assembly provided by an embodiment of the present application;

FIG. 5 is a schematic structural diagram of a display device provided by an embodiment of the present application;

FIG. 6 is a schematic diagram illustrating the variation of voltage/time (U/t) when the diffraction unit of the optical waveguide assembly performs power-on manipulation according to an embodiment of the present application.

Among them, the corresponding relationship between the reference numerals and the component names in Fig. 1 to Fig. 6 is:

1. Waveguide plate; 2. The first diffraction unit; 21. The first coupled-in liquid crystal grating; 22, The first coupled-out liquid crystal grating; 3. The second diffraction unit; Coupling liquid crystal grating; 4, liquid crystal layer; 41, liquid crystal; 5, alignment film layer; 6, first electrode layer; 7, second electrode layer; 8, substrate; 9, protective layer; 10, projector; 101 , display chip; 102, projection lens; 11, spacer.

detailed description

In order to understand the above objects, features and advantages of the present invention more clearly, the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments. It should be noted that the embodiments of the present application and the features in the embodiments may be combined with each other in the case of no conflict.

The optical waveguide assembly and the display device provided by this application are mainly used in the technical fields of virtual reality, augmented reality and mixed reality. Whether it is virtual reality, augmented reality or mixed reality, the source image is converted into two kinds of images to enter the left and right respectively. , the right human eye, resulting in visual difference, so as to give people a 3D effect.

Specifically, the display device includes an optical projector and an optical waveguide assembly, and the optical waveguide assembly further includes a waveguide sheet and a coupling-in grating and an out-coupling grating provided thereon.

The light projector projects the image light to the coupling-in grating, the coupling-in grating diffracts the light into the waveguide sheet, the light is totally reflected and transmitted in the waveguide sheet, the light is transmitted to the coupling-out grating, and the coupling-out grating then diffracts the light to the outside of the waveguide sheet. The visible area is thus received by the human eye.

Since it needs to be observed by the human eye, the image light projected by the projector is visible light, and the visible light is divided into various colors of light, and the wavelengths of different colors of light are different. The diffraction angle of light is related to the wavelength of the light and the period of the grating, and when the same grating diffracts light of different colors, the diffraction angle and diffraction efficiency are different, resulting in the imbalance of the proportion and exit angle of the light of different colors after transmission, resulting in uneven color, Display color cast and rainbow effect and other issues.

Red, green and blue light is the basic color light, and other colors can be displayed by the combination of two or three of them, so the projector only needs to project red, green and blue light, and then couple in and out The grating only needs to diffract these three colors of light.

The optical waveguide assembly and the display device provided by the present application will be described in detail below.

Example 1

FIG. 1 is a schematic structural diagram of an optical waveguide assembly provided by an embodiment of the present application.

As shown in FIG. 1, this embodiment provides an optical waveguide assembly, including:

A waveguide sheet 1, comprising a first optical surface and a second optical surface opposite to the first optical surface, and the waveguide sheet 1 is used for total reflection and transmission of light therein; and

at least two diffractive units, where

- a first diffractive unit 2, comprising a first in-coupled liquid crystal grating 21 and a first out-coupled liquid crystal grating 22 arranged on the first optical surface, the first in-coupled liquid crystal grating 21 and the first out-coupled liquid crystal grating 22 are arranged to be applied When the voltage or no voltage is applied, it is in the grating state in the first direction, and the first coupling into the liquid crystal grating 21 is used to couple the first light into the waveguide sheet 1 under the condition of the grating state in the first direction. The outgoing liquid crystal grating 22 is used to couple the first light out of the waveguide sheet 1 to the visible area under the condition of the grating state in the first direction; and

- a second diffractive unit 3, comprising a second in-coupled liquid crystal grating 31 and a second out-coupled liquid crystal grating 32 arranged on the second optical surface, the second in-coupled liquid crystal grating 31 and the second out-coupled liquid crystal grating 32 are arranged to be applied When the voltage or no voltage is applied, it is in the grating state in the first direction, and the second coupling into the liquid crystal grating 31 is used to couple the second light into the waveguide sheet 1 under the condition of being in the grating state in the first direction, and the second coupling The liquid crystal grating 32 is used to couple the second light out of the waveguide sheet 1 to the visible area when the first direction is in the grating state, and the wavelength of the second light is different from that of the first light.

Wherein, by alternately applying voltages to each diffraction unit, the first coupling into the liquid crystal grating 21 and the first coupling out of the liquid crystal grating 22 of the first diffraction unit 2 or the second coupling in the liquid crystal grating 31 and the second coupling of the second diffraction unit 3 The out-coupling liquid crystal grating 32 is in a grating state in the first direction, so that the first light and the second light with different wavelengths can be diffracted respectively.

The specific working principle of the optical waveguide assembly provided in this embodiment is as follows:

When the first light is to be diffracted, the first coupled-in liquid crystal grating 21 and the first out-coupled liquid crystal grating 22 of the first diffraction unit 2 are in the grating state in the first direction by applying voltage or no voltage. The second coupled-in liquid crystal grating 31 and the second coupled-out liquid crystal grating 32 of the diffraction unit 3 are not in the grating state in the first direction. At this time, the grating of the first diffraction unit 2 diffracts the first light, and the second diffraction The grating of unit 3 does not diffract light.

When the second light is to be diffracted, the first coupled-in liquid crystal grating 21 and the first out-coupled liquid crystal grating 22 of the first diffraction unit 2 are not in the grating state in the first direction by applying a voltage or no voltage. The second coupled-in liquid crystal grating 31 and the second coupled-out liquid crystal grating 32 of the second diffraction unit 3 are in the grating state in the first direction. At this time, the grating of the first diffraction unit 2 does not diffract light, and the second diffraction unit The grating of 3 diffracts the second light.

In the optical waveguide assembly provided in this embodiment, a diffractive unit is provided on each of the two surfaces of the waveguide sheet 1, and each diffractive unit includes a coupled-in liquid crystal grating and an out-coupling liquid crystal grating, and the coupled-in liquid crystal grating and the coupled-out liquid crystal grating are set In order to be in a grating state in the first direction when a voltage is applied or not The grating of 3 is in a grating state in the first direction, thereby diffracting light with different wavelengths (lights with different colors have different wavelengths), and the optical waveguide assembly provided in this embodiment only needs a single-layer waveguide sheet to achieve full color The display is simple in structure, light and thin, small in size, simple in control method, and easy to manufacture. In addition, when the optical waveguide assembly provided in this embodiment only uses a single-layer waveguide sheet, light of different wavelengths is diffracted by different gratings, thereby ensuring a certain diffraction angle of light of different wavelengths, improving the diffraction efficiency and avoiding the Color casts, chromatic dispersion, color unevenness, and rainbow effects. Moreover, the first coupled-in liquid crystal grating 21, the first coupled-out liquid crystal grating 22, the second coupled-in liquid crystal grating 31, and the second coupled-out liquid crystal grating 32 of the optical waveguide assembly provided in this embodiment are equivalent to ordinary one-dimensional surface relief gratings. Therefore, the viewing angle range is mainly affected by the refractive index of the waveguide sheet 1 itself, and can have the viewing angle range that ordinary surface relief grating waveguide sheets can achieve. The viewing angle is large, about 40°-60°.

Specifically, the period of the first coupled-in liquid crystal grating 21 and the first coupled-out liquid crystal grating 22 is set to correspond to the wavelength of the first light, that is, the period of the first coupled-in liquid crystal grating 21 and the first coupled-out liquid crystal grating 22 is equal to The wavelengths of the first light rays are not much different, so as to ensure a certain diffraction angle of the first light rays and improve the diffraction efficiency. The period of the second in-coupled liquid crystal grating 31 and the second out-coupled liquid crystal grating 32 is set to correspond to the wavelength of the second light, that is, the period of the second in-coupled liquid crystal grating 31 and the second out-coupled liquid crystal grating 32 is the same as that of the second light The wavelength of the ray is not much different, so as to ensure a certain diffraction angle of the second light and improve the diffraction efficiency.

Further, in this embodiment, the first light is blue light and a part of green light with a wavelength close to the blue light, and the second light is red light and another part of the green light with a wavelength close to the red light. Those skilled in the art can easily know that, in other embodiments, the first light or the second light is light of other colors should also be within the protection scope of the present application.

In this embodiment, the first coupled-in liquid crystal grating 21, the first coupled-out liquid crystal grating 22, the second coupled-in liquid crystal grating 31, and the second coupled-out liquid crystal grating 32 are set to be gratings in the first direction when a voltage is applied state, a uniform dielectric state in the first direction when no voltage is applied, that is, the optical waveguide assembly provided in this embodiment is controlled to the first coupled-in liquid crystal grating 21, the first coupled-out liquid crystal grating 22, and the second coupled-in liquid crystal grating 31 and the second out-coupled liquid crystal grating 32 apply voltage to switch the working state of each grating of each diffraction unit. Further, the first direction is parallel to the first optical surface or the second optical surface of the waveguide sheet 1, the first coupled-in liquid crystal grating 21, the first coupled-out liquid crystal grating 22, the second coupled-in liquid crystal grating 31 and the second The out-coupled liquid crystal grating 32 is in a one-dimensional grating state in the first direction when a voltage is applied. The specific working principle of the optical waveguide assembly provided in this embodiment is as follows:

When the first light needs to be diffracted, a voltage is applied to the first coupled-in liquid crystal grating 21 and the first coupled-out liquid crystal grating 22 of the first diffraction unit 2 , and the second coupled-in liquid crystal grating 31 and the second coupled-in liquid crystal grating of the second diffraction unit 3 No voltage is applied to the liquid crystal grating 32. At this time, the grating of the first diffraction unit 2 is in a one-dimensional grating state in the first direction, and performs a diffraction effect on the first light. The grating of the second diffraction unit 3 is in the state of a uniform medium in the first direction, and does not diffract light.

When the second light needs to be diffracted, no voltage is applied to the first coupled-in liquid crystal grating 21 and the first coupled-out liquid crystal grating 22 of the first diffraction unit 2, and the second coupled-in liquid crystal grating 31 and the second coupled-in liquid crystal grating of the second diffraction unit 3 When a voltage is applied to the out-coupled liquid crystal grating 32, at this time, the grating of the first diffraction unit 2 is in a state of a uniform medium in the first direction, and does not diffract light. The grating of the second diffraction unit 3 is in a one-dimensional grating state in the first direction, and plays a diffracting effect on the second light.

In other embodiments, the first coupled-in liquid crystal grating 21, the first coupled-out liquid crystal grating 22, the second coupled-in liquid crystal grating 31, and the second coupled-out liquid crystal grating 32 can also be set to be in the first direction when a voltage is applied Uniform dielectric state, grating state in the first direction when no voltage is applied.

FIG. 2 is a schematic structural diagram of a liquid crystal grating of an optical waveguide assembly according to an embodiment of the application, and FIG. 3 is a schematic diagram of a working state of the liquid crystal grating of the optical waveguide assembly according to an embodiment of the application.

As shown in FIG. 2 and FIG. 3 , in this embodiment, the first coupled-in liquid crystal grating 21 , the first coupled-out liquid crystal grating 22 , the second coupled-in liquid crystal grating 31 and the second coupled-out liquid crystal grating 32 are used as liquid crystal gratings, They include:

The liquid crystal layer 4 includes a plurality of liquid crystals 41, and the liquid crystals 41 are cholesteric liquid crystals;

Two alignment film layers 5, the two alignment film layers 5 are arranged on both sides of the liquid crystal layer 4 opposite to each other and are used to give the initial director of the liquid crystal 41;

the first electrode layer 6; and

The second electrode layer 7 , the first electrode layer 6 and the second electrode layer 7 are disposed on the outside of the two alignment film layers 5 opposite to each other.

After a voltage is applied to the first electrode layer 6 and the second electrode layer 7, an electric field E is formed between the first electrode layer 6 and the second electrode layer 7, so that the liquid crystal 41 located in the electric field E deflects the director, and then switches the working state of the grating. That is, the operating state of the grating is switched by controlling whether a voltage is applied to the first electrode layer 6 and the second electrode layer 7 or not.

FIG. 4 is a schematic diagram of another working state of the liquid crystal grating of the optical waveguide assembly provided by an embodiment of the present application.

More specifically it works as follows:

When the first light is to be diffracted, a voltage (the voltage value is not zero) is applied to the first coupled-in liquid crystal grating 21 and the first coupled-out liquid crystal grating 22 of the first diffraction unit 2, and the first coupled-in liquid crystal grating 21 and the first coupled-out liquid crystal grating 22 are The output liquid crystal grating 22 is in a one-dimensional grating state in the first direction (the horizontal direction in this embodiment), as shown in FIG. The coupled-in liquid crystal grating 31 and the second coupled-out liquid crystal grating 32 do not apply a voltage (the voltage value is zero). In the horizontal direction), it is in a homogeneous medium state, as shown in FIG. 4 , without diffracting light, that is, there is no grating on the second optical surface equivalent to the waveguide sheet 1 at this moment.

When the second light is to be diffracted, no voltage is applied to the first coupled-in liquid crystal grating 21 and the first coupled-out liquid crystal grating 22 of the first diffraction unit 2 (the voltage value is zero), and the first coupled-in liquid crystal grating 21 and the first coupled liquid crystal grating 22 are The liquid crystal grating 22 is in the state of a homogeneous medium in the first direction (the horizontal direction in this embodiment), as shown in FIG. There is a grating, and at the same time, a voltage (the voltage value is not zero) is applied to the second coupled-in liquid crystal grating 31 and the second coupled-out liquid crystal grating 32 of the second diffraction unit 3. At this time, the second coupled-in liquid crystal grating 31 and the second coupled The outgoing liquid crystal grating 32 is in a one-dimensional grating state in the first direction (the horizontal direction in this embodiment), as shown in FIG. 3 , and produces a diffraction effect on the second light.

The liquid crystal 41 of the first coupled-in liquid crystal grating 21, the first coupled-out liquid crystal grating 22, the second coupled-in liquid crystal grating 31, and the second coupled-out liquid crystal grating 32 of the optical waveguide assembly provided in this embodiment is a cholesteric liquid crystal. The steroidal liquid crystal has a helical pitch, so that the first coupled-in liquid crystal grating 21, the first coupled-out liquid crystal grating 22, the second coupled-in liquid crystal grating 31, and the second coupled-out liquid crystal grating 32 have a grating period, and then the first electrode layer 6 and the first The second electrode layer 7 does not need to be configured as a periodic structure, and the manufacturing process is simple and convenient. The pitch of the cholesteric liquid crystal is the grating period. By changing the magnitude of the applied voltage, the pitch of the cholesteric liquid crystal can be slightly changed, that is, the size of the grating period can be fine-tuned by changing the magnitude of the applied voltage. However, the size of the liquid crystal pitch is mainly determined by the liquid crystal material itself, and the size of the applied voltage can only play a role in fine-tuning.

Further, in this embodiment, the liquid crystal pitch of the first coupled-in liquid crystal grating 21 and the first coupled-out liquid crystal grating 22 is 340 nm, that is, the grating period of the first coupled-in liquid crystal grating 21 and the first coupled-out liquid crystal grating 22 It is 340nm, which can better diffract blue light of all wavelengths and part of green light close to the wavelength of blue light, with good color rendering effect and high diffraction efficiency.

The liquid crystal pitch of the second coupled-in LC grating 31 and the second coupled-out LC grating 32 is 440 nm, that is, the grating period of the second coupled-in LC grating 31 and the second coupled-out LC grating 32 is 440 nm, so as to better diffract all wavelengths The red light and another part of the green light whose wavelength is close to the red light have good color rendering effect and high diffraction efficiency.

Furthermore, the thickness of the liquid crystal layer 4 is not more than 2.5 times the pitch of the liquid crystal, and the color rendering effect is good and the diffraction efficiency is high.

In this embodiment, the voltage applied to the first coupled-in liquid crystal grating 21, the first coupled-out liquid crystal grating 22, the second coupled-in liquid crystal grating 31, and the second coupled-out liquid crystal grating 32 is a square wave alternating current of 1KHz, and the voltage amplitude The value is 5V to 22V.

In this embodiment, the first electrode layer 6 and the second electrode layer 7 are made of indium tin oxide (ITO).

In this embodiment, the material of the liquid crystal 41 of the liquid crystal layer 4 can be composed of the main body of the BL015 nematic liquid crystal 41 and the chiral agent ZLI-811, and the pitch of the cholesteric liquid crystal can be adjusted by the concentration of the chiral agent.

The first coupled-in liquid crystal grating 21, the first coupled-out liquid crystal grating 22, the second coupled-in liquid crystal grating 31, and the second coupled-out liquid crystal grating 32 provided in this embodiment further include a plurality of spacers 11 (not shown in the figure) , a plurality of spacers 11 are distributed between the two alignment film layers 5 to support the two alignment film layers 5 and maintain and determine the distance between them.

Further, the waveguide sheet 1 constitutes the substrate 8 of the liquid crystal grating, and the first coupled-in liquid crystal grating 21 , the first coupled-out liquid crystal grating 22 , the second coupled-in liquid crystal grating 31 and the second coupled-out liquid crystal grating provided in this embodiment 32 further includes a protective layer 9 respectively, and the substrate 8 and the protective layer 9 are disposed on the outside of the first electrode layer 6 and the second electrode layer 7 opposite to each other.

Specifically, the protective layer 9 is made of a glass material and has a thickness of 0.1 mm˜0.3 mm.

In this embodiment, the thickness of the protective layer 9 is smaller than the thickness of the waveguide sheet 1 . Further, the thickness of the waveguide sheet 1 can be 0.3-2.5 mm, the refractive index is 1.4-2.2, and the light transmission effect is good. Within this range, the higher the refractive index of the waveguide sheet 1, the better.

In the present embodiment, the spacers 11 are spheres arranged in a certain pattern with a diameter corresponding to the thickness of the liquid crystal layer 4 or cylinders arranged in a certain pattern with a height corresponding to the thickness of the liquid crystal layer 4 .

Further, the first coupled-in liquid crystal grating 21 , the first coupled-out liquid crystal grating 22 , the second coupled-in liquid crystal grating 31 and the second coupled-out liquid crystal grating 32 may further include blocking members, and the blocking members are located in the two alignment film layers 5 . It is arranged between and around the liquid crystal layer 4 to prevent the liquid crystal 41 from overflowing.

The manufacturing methods of the first coupled-in liquid crystal grating 21, the first coupled-out liquid crystal grating 22, the second coupled-in liquid crystal grating 31, and the second coupled-out liquid crystal grating 32 provided in this embodiment are as follows:

Provide the waveguide sheet 1 as the substrate 8 of each liquid crystal grating, and clean the waveguide sheet 1;

providing a protective layer 9, and cleaning the protective layer 9;

A first electrode layer 6 and a second electrode layer 7 are respectively arranged on the waveguide sheet 1 and the protective layer 9;

The alignment film layer 5 is spin-coated on the first electrode layer 6 and the second electrode layer 7, respectively, and aligned;

Spin-coat spacers 11 between the two alignment film layers 5;

Glue the protective layer 9 and the waveguide sheet 1, wherein the alignment direction of the alignment film layer 5 on the protective layer 9 side is opposite to the alignment direction of the alignment film layer 5 on the waveguide sheet 1 side;

The liquid crystal 41 is poured and sealed to complete the fabrication of the grating.

The pitches of the cholesteric liquid crystals of the first coupled-in LC grating 21 , the first coupled-out LC grating 22 , the second coupled-in LC grating 31 and the second coupled-out LC grating 32 produced by the manufacturing method provided in this embodiment are For the grating period, the pitch can be fine-tuned by changing the voltage values applied to the first coupled-in liquid crystal grating 21, the first coupled-out liquid crystal grating 22, the second coupled-in liquid crystal grating 31, and the second coupled-out liquid crystal grating 32, thereby fine-tuning the gratings. The size of the cycle is flexible and convenient to use. And since the cholesteric liquid crystal provides grating periods for the first coupled-in liquid crystal grating 21, the first coupled-out liquid crystal grating 22, the second coupled-in liquid crystal grating 31 and the second coupled-out liquid crystal grating 32, the first electrode layer 6 and the The second electrode layer 7 does not need to be fabricated as a periodic structure, the fabrication process is simple and convenient, and the production is convenient.

Specifically, when cleaning the waveguide sheet 1, acetone, methanol and isopropanol were used to ultrasonically clean the waveguide sheet 1 for 10 minutes, respectively. During the alignment, the rubbing alignment method or the optical alignment method is adopted for alignment, and the produced grating has good optical performance.

Of course, regarding the structure and fabrication of the first coupled-in LC grating 21 , the first coupled-out LC grating 22 , the second coupled-in LC grating 31 and the second coupled-out LC grating 32 , except that the waveguide sheet is directly used as the liquid crystal according to the above embodiment In addition to the grating substrate, separate substrates, such as sheets of glass material, can also be used. Accordingly, after the liquid crystal grating and the waveguide sheet are fabricated independently of each other, they can be assembled together. In this case, the thickness of the optical waveguide assembly is increased due to the additional glass sheet (substrate), but this embodiment may be an appropriate choice for some specific process conditions and/or applications in practice.

Example 2

The optical waveguide assembly provided in this embodiment further includes a third diffractive unit (not shown in the figure), the third diffractive unit includes a third coupled-in liquid crystal grating and a third coupled-out liquid crystal grating, and the third coupled-in liquid crystal grating is provided on the An in-coupling liquid crystal grating 21 is disposed on a surface opposite to the waveguide sheet 1 or on a surface of the second coupling-in liquid crystal grating 31 opposite to the waveguide sheet 1, and a third out-coupling liquid crystal grating is disposed on the first out-coupling liquid crystal grating The grating 22 is located on a surface opposite to the waveguide sheet 1 or is arranged on a surface of the second out-coupling liquid crystal grating 32 opposite to the waveguide sheet 1, and the third coupling-in liquid crystal grating and the third out-coupling liquid crystal grating are arranged to A grating state in the first direction when voltage or no voltage is applied;

The third coupled-in liquid crystal grating is used for coupling the third light into the waveguide sheet 1 under the condition of the grating state in the first direction, and the third coupled-out liquid crystal grating is used under the condition of the grating state in the first direction The third light is coupled out of the waveguide sheet 1 to the visible area. The wavelength of the third light is different from that of the first light and the second light, and the third light intersects the waveguide sheet 1 .

By alternately applying voltages to the diffractive units, the first coupling in liquid crystal grating 21 and the first coupling out liquid crystal grating 22 of the first diffractive unit 2 and the second coupling in liquid crystal grating 31 and the second coupling out of the second diffractive unit 3 The liquid crystal grating 32 or the third coupled-in liquid crystal grating and the third coupled-out liquid crystal grating of the third diffractive unit are in the grating state in the first direction, so that the first light, the second light and the third light with different wavelengths can be diffracted respectively.

In this embodiment, the third coupled-in liquid crystal grating and the third coupled-out liquid crystal grating are set to be a one-dimensional grating state in the first direction when a voltage is applied, and a uniform dielectric state in the first direction when no voltage is applied. The specific working principle of the optical waveguide assembly provided in this embodiment is as follows:

When the first light needs to be diffracted, a voltage is applied to the first coupled-in liquid crystal grating 21 and the first coupled-out liquid crystal grating 22 of the first diffraction unit 2 , and the second coupled-in liquid crystal grating 31 and the second coupled-in liquid crystal grating of the second diffraction unit 3 The output liquid crystal grating 32 and the third coupled-in liquid crystal grating and the third coupled-out liquid crystal grating of the third diffraction unit do not apply voltage. At this time, the grating of the first diffraction unit 2 is in a one-dimensional grating state in the first direction. A ray of light is diffracted. The gratings of the second diffractive unit 3 and the third diffractive unit are in a uniform medium state in the first direction and do not diffract light.

When the second light needs to be diffracted, no voltage is applied to the first coupled-in liquid crystal grating 21 and the first coupled-out liquid crystal grating 22 of the first diffraction unit 2, and the second coupled-in liquid crystal grating 31 and the second coupled-in liquid crystal grating of the second diffraction unit 3 The voltage is applied to the out-coupling liquid crystal grating 32, and the third coupling-in liquid crystal grating and the third out-coupling liquid crystal grating of the third diffraction unit do not apply voltage. At this time, the gratings of the first diffraction unit 2 and the third diffraction unit are in the first direction It is a homogeneous medium state and does not diffract light. The grating of the second diffraction unit 3 is in a one-dimensional grating state in the first direction, and plays a diffracting effect on the second light.

When the third light is to be diffracted, the first coupling-in liquid crystal grating 21 and the first coupling-out liquid crystal grating 22 of the first diffraction unit 2 and the second coupling-in liquid crystal grating 31 and the second coupling-out liquid crystal grating of the second diffraction unit 3 No voltage is applied to the grating 32, and a voltage is applied to the third coupled-in liquid crystal grating and the third coupled-out liquid crystal grating of the third diffraction unit. At this time, the gratings of the first diffraction unit 2 and the second diffraction unit 3 are in the first direction: The state of a homogeneous medium does not diffract light. The grating of the third diffraction unit is in a one-dimensional grating state in the first direction, and plays a diffracting effect on the third light.

In the optical waveguide assembly provided in this embodiment, three diffractive units are set on two surfaces of the waveguide sheet 1 . It is set to be in a grating state in the first direction when a voltage is applied or not, and the first diffraction unit 2, the second diffraction unit 2 and the second diffraction unit are set to be in a grating state by whether to apply a voltage to the coupled-in liquid crystal grating and the coupled-out liquid crystal grating of the corresponding diffraction unit. The grating of unit 3 or the third diffraction unit is in a grating state in the first direction, diffracting light with different wavelengths (lights with different colors have different wavelengths), so the optical waveguide assembly provided in this embodiment only needs to use a single-layer waveguide sheet The full-color display can be realized, the structure is simple, light and thin, compact, the control method is simple, and it is easy to manufacture. In addition, the optical waveguide assembly provided in this embodiment only uses a single-layer waveguide sheet to diffract light of different wavelengths by different gratings, thereby ensuring that the diffraction angle of light of different wavelengths is constant, improving the diffraction efficiency, and avoiding chromatic aberrations. Partition, dispersion, color unevenness, and rainbow effects. In addition, the optical waveguide assembly provided in this embodiment has the first coupled-in liquid crystal grating 21, the first coupled-out liquid crystal grating 22, the second coupled-in liquid crystal grating 31, the second coupled-out liquid crystal grating 32, the third coupled-in liquid crystal grating and the third coupled-in liquid crystal grating The three-coupled-out liquid crystal grating is equivalent to an ordinary one-dimensional surface relief grating. Therefore, the range of the field of view is mainly affected by the refractive index of the waveguide sheet 1 itself. Large, about 40° to 60°.

Further, the period of the third coupled-in liquid crystal grating and the third coupled-out liquid crystal grating is set to correspond to the wavelength of the third light, that is, the period of the third coupled-in liquid crystal grating and the third coupled-out liquid crystal grating is the same as the third light. The wavelengths are not much different, so as to ensure a certain diffraction angle of the third light rays and improve the diffraction efficiency.

In this embodiment, the first light is blue light, the second light is green light, and the third light is red light. Since each color light has a grating with a corresponding period for diffraction, the diffraction angle is better controlled and the diffraction efficiency is higher. Those skilled in the art can easily know that, in other embodiments, the first light, the second light and the third light are light of other colors, which should also fall within the protection scope of the present application.

Example 3

FIG. 5 is a schematic structural diagram of a display device according to an embodiment of the present application.

As shown in FIG. 5 , this embodiment also provides a display device, including:

The projector 10 includes a display chip 101 and a projection lens 102 , the display chip 101 is used to control the first light and the second light that output a display image at a certain frequency and time sequence, and the projection lens 102 is used to project the display chip 101 output light; and

The optical waveguide assembly, the optical waveguide assembly is the optical waveguide assembly described in any of the above embodiments, at least the first coupling into the liquid crystal grating 21 of the first diffraction unit 2 of the optical waveguide assembly and the second coupling into the liquid crystal of the second diffraction unit 3 The grating 31 is used to couple the light projected by the projection lens 102 into the waveguide sheet 1 of the optical waveguide assembly. The out-coupling liquid crystal grating 32 is used to couple the light coupled into the waveguide sheet 1 out of the waveguide sheet 1 to the visible area,

By alternately applying voltage to each diffractive unit, the optical waveguide assembly is controlled at the same frequency as the output of the first light and the second light, so that the grating of the first diffractive unit 2 or the second diffractive unit 3 is correspondingly The first direction is in a grating state, so as to diffract the first light rays and the second light rays with different wavelengths respectively.

The detailed working principle of the display device provided in this embodiment is as follows:

When the display chip 101 outputs the first light for displaying the image, a voltage is applied to the first coupled-in liquid crystal grating 21 and the first coupled-out liquid crystal grating 22 (that is, the voltage value is not zero), and the first coupled-in liquid crystal grating 21 and the first The out-coupling liquid crystal grating 22 is in a one-dimensional grating state in the first direction (the horizontal direction in this embodiment), as shown in FIG. 3 , and has a diffraction effect on the light. At the same time, no voltage is applied to the second coupled-in liquid crystal grating 31 and the second coupled-out liquid crystal grating 32 (the voltage value is zero), and the second coupled-in liquid crystal grating 31 and the second coupled-out liquid crystal grating 32 are in the first direction (in this In the embodiment, the horizontal direction) is a homogeneous medium state, as shown in FIG. 4 , without diffracting light, that is, there is no grating on the second optical surface equivalent to the waveguide sheet 1 at this moment.

When the display chip 101 outputs the second light for displaying images, no voltage is applied to the first coupled-in liquid crystal grating 21 and the first coupled-out liquid crystal grating 22 (ie, the voltage value is zero), and the first coupled-in liquid crystal grating 21 and the first The out-coupling liquid crystal grating 22 is in the state of a homogeneous medium in the first direction (the horizontal direction in this embodiment), as shown in FIG. There is no grating, and a voltage is applied to the second coupled-in liquid crystal grating 31 and the second coupled-out liquid crystal grating 32 at the same time (the voltage value is not zero), and the second coupled-in liquid crystal grating 31 and the second coupled-out liquid crystal grating 32 are on the first side. The upward direction (that is, the horizontal direction in this embodiment) is the working state of the one-dimensional grating, as shown in FIG. 3 , diffracting the light.

That is, the optical waveguide assembly outputs the first light and the second light for displaying the image at a certain frequency. When the frequency is greater than or equal to the refresh rate of the human eye, what the human eye observes is the color image synthesized by the two parts of light (when the first light is blue light and part of green light, and the second light is red light and another part of green light , what the human eye observes is the full-color image after the two parts are synthesized).

The projector 10 of the display device provided in this embodiment projects the first light and the second light at a certain frequency, and the optical waveguide assembly switches the grating state of the first diffraction unit 2 or the second diffraction unit 3 in the first direction correspondingly at the same frequency , to diffract light with different wavelengths (lights with different colors have different wavelengths), so that the display device provided in this embodiment only needs to use a single-layer waveguide sheet to realize full-color display, and has a simple structure, light weight, compactness, and simple control method. Easy to manufacture. In addition, when the display device provided in this embodiment only uses a single-layer waveguide sheet, light with different wavelengths is diffracted by different gratings, thereby ensuring a certain diffraction angle of light with different wavelengths, improving the diffraction efficiency, and avoiding color. Partition, dispersion, color unevenness, and rainbow effects. Moreover, the first coupled-in liquid crystal grating 21, the first coupled-out liquid crystal grating 22, the second coupled-in liquid crystal grating 31, and the second coupled-out liquid crystal grating 32 of the display device provided in this embodiment are equivalent to ordinary one-dimensional surface relief gratings, so , the viewing angle range is mainly affected by the refractive index of the waveguide sheet 1 itself, and it can have the viewing angle range that ordinary surface relief grating waveguide sheets can achieve, and the viewing angle is large, about 40°-60°.

Further, as shown in FIG. 6 , the first coupling in liquid crystal grating 21 of the first diffraction unit 2 , the first coupling out liquid crystal grating 22 and the second coupling in liquid crystal grating 31 and the second coupling in the liquid crystal grating 22 of the second diffractive unit 3 respectively The out-coupling liquid crystal grating 32 applies corresponding periodic voltages respectively, so that the first coupling-in liquid crystal grating 21 of the first diffraction unit 2 , the first coupling-out liquid crystal grating 22 and the second coupling-in liquid crystal grating 31 of the second diffraction unit 3 . The second out-coupled liquid crystal grating 32 is in a grating state in the first direction, and the control method is simple and convenient. Specifically, the period of the voltage applied to the first coupled-in liquid crystal grating 21 and the first coupled-out liquid crystal grating 22 of the first diffraction unit 2 is the same as that applied to the second coupled-in liquid crystal grating 31 and the second coupled-out liquid crystal grating of the second diffraction unit 3 The periods of the voltages applied by the grating 32 are staggered from each other. The applied voltage is preferably a square-wave alternating current with its own frequency of 1KHz, as shown in Figure 6, where the voltage value determines the period of the diffraction grating formed and the pitch of the corresponding cholesteric liquid crystal, and the voltage amplitude is generally 5 ~ 22V, You can choose according to actual needs.

Optionally, the frequency at which the display chip 101 outputs the first light and the second light is 60 Hz, and the full-color display effect is good.

Example 4

In this embodiment, the display chip 101 is used to control the output of the first light, the second light and the third light for displaying the image at a certain frequency and time sequence. Correspondingly, the optical waveguide assembly further includes a third diffractive unit.

The optical waveguide assembly switches the grating of the first diffractive unit 2, the second diffractive unit 3 or the third diffractive unit to the grating state in the first direction at the same frequency as the output of the first light, the second light and the third light, so as to Different wavelengths of light are diffracted (lights with different colors have different wavelengths), so that the display device provided in this embodiment only needs to use a single-layer waveguide sheet to realize full-color display, and has a simple structure, light weight, compactness, simple control method, and easy production. manufacture. In addition, when the display device provided in this embodiment only uses a single-layer waveguide sheet, light with different wavelengths is diffracted by different gratings, thereby ensuring a certain diffraction angle of light with different wavelengths, improving the diffraction efficiency, and avoiding color. Partition, dispersion, color unevenness, and rainbow effects. Moreover, the first coupled-in liquid crystal grating 21, the first coupled-out liquid crystal grating 22, the second coupled-in liquid crystal grating 31, and the second coupled-out liquid crystal grating 32 of the display device provided in this embodiment are equivalent to ordinary one-dimensional surface relief gratings, so , the viewing angle range is mainly affected by the refractive index of the waveguide sheet 1 itself, and it can have the viewing angle range that ordinary surface relief grating waveguide sheets can achieve, and the viewing angle is large, about 40°-60°.

Further, the first light is blue light, the second light is green light, and the third light is red light. Since each color light has a grating with a corresponding period for diffraction, the diffraction angle is better controlled and the diffraction efficiency is higher. Those skilled in the art can easily know that, in other embodiments, the first light, the second light and the third light are light of other colors, which should also fall within the protection scope of the present application.

In the description of the present invention, it should be noted that the orientation or positional relationship indicated by the terms "upper", "lower", "inner", "outer", etc. is based on the orientation or positional relationship shown in the accompanying drawings, and is only for convenience The invention is described and simplified without indicating or implying that the device or element referred to must have a particular orientation, be constructed and operate in a particular orientation, and therefore should not be construed as limiting the invention. Furthermore, the terms "first," "second," etc. are used for descriptive purposes only and should not be construed to indicate or imply relative importance.

In the description of the present invention, it should be noted that the terms "installation", "communication" and "connection" should be understood in a broad sense unless otherwise expressly specified and limited. For example, it may be a fixed connection or a detachable connection. Connection, or integral connection; may be mechanical connection or electrical connection; may be direct communication, or indirect communication through an intermediate medium, and may be internal communication between two elements. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood in specific situations. Also, in the description of the present invention, unless otherwise specified, "plurality" means two or more.

The above are only preferred embodiments of the present invention and are not intended to limit the present invention. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present application. Inside.

Claims

An optical waveguide assembly, characterized in that it includes:

A waveguide sheet (1), comprising a first optical surface and a second optical surface opposite to the first optical surface, and the waveguide sheet (1) is used for total reflection and transmission of light therein; and

at least two diffractive units, where

- a first diffractive unit (2) comprising a first in-coupled liquid crystal grating (21) and a first out-coupled liquid crystal grating (22) provided on said first optical surface, said first in-coupled liquid crystal grating (21) and The first out-coupled liquid crystal grating (22) is set to be in a grating state in a first direction when a voltage is applied or not, and the first coupled-in liquid crystal grating (21) is used to be a grating in the first direction The first light is coupled into the waveguide sheet (1) in the state of the first light, and the first out-coupling liquid crystal grating (22) is used to couple out the first light in the state of grating in the first direction the waveguide sheet (1) to the visible area, and

- a second diffractive unit (3) comprising a second in-coupled liquid crystal grating (31) and a second out-coupled liquid crystal grating (32) provided on the second optical surface, the second in-coupled liquid crystal grating (31) and The second out-coupled liquid crystal grating (32) is set to be in a grating state in a first direction when a voltage is applied or not, and the second coupled-in liquid crystal grating (31) is used to be a grating in the first direction The second light is coupled into the waveguide sheet (1) in the state of the first direction, and the second out-coupling liquid crystal grating (32) is used to couple the second light out when the first direction is in the grating state The waveguide sheet (1) reaches the visible area, and the wavelength of the second light is different from the wavelength of the first light;

Wherein, by alternately applying voltages to each diffractive unit, the first coupled-in liquid crystal grating (21) and the first coupled-out liquid crystal grating (22) of the first diffractive unit (2) or the second diffractive unit (3) ) of the second coupled-in liquid crystal grating (31) and the second coupled-out liquid crystal grating (32) are in the grating state in the first direction, so that the first light and the second light with different wavelengths can be diffracted respectively.
The optical waveguide assembly according to claim 1, wherein the period of the first coupled-in liquid crystal grating (21) and the first coupled-out liquid crystal grating (22) is set to be the same as the wavelength of the first light Corresponding;

The period of the second coupled-in liquid crystal grating (31) and the second coupled-out liquid crystal grating (32) is set to correspond to the wavelength of the second light.
The optical waveguide assembly according to claim 2, wherein the first light is blue light and a part of green light with a wavelength close to the blue light, and the second light is red light with a wavelength close to the red light Another part of the green light.
The optical waveguide assembly according to claim 1, wherein the first coupled-in liquid crystal grating (21), the first coupled-out liquid crystal grating (22), and the second coupled-in liquid crystal grating (31) and the second out-coupled liquid crystal grating (32) is set to be in a grating state in a first direction when a voltage is applied, and in a uniform dielectric state in the first direction when no voltage is applied.
The optical waveguide assembly according to claim 4, wherein the first direction is parallel to the first optical surface or the second optical surface of the waveguide sheet (1), and the first coupled-in liquid crystal grating ( 21) The first coupled-out liquid crystal grating (22), the second coupled-in liquid crystal grating (31), and the second coupled-out liquid crystal grating (32) are one-dimensional in a first direction when a voltage is applied raster state.
The optical waveguide assembly according to any one of claims 1 to 5, wherein the first coupled-in liquid crystal grating (21), the first coupled-out liquid crystal grating (22), the second coupled-in liquid crystal grating (22) The incoming liquid crystal grating (31) and the second out-coupling liquid crystal grating (32) respectively comprise:

a liquid crystal layer (4), comprising a plurality of liquid crystals (41), the liquid crystals are cholesteric liquid crystals;

Two alignment film layers (5), the two alignment film layers (5) are arranged on both sides of the liquid crystal layer (4) opposite to each other at intervals and are used to give the initial director of the liquid crystal (41);

a first electrode layer (6); and

The second electrode layer (7), the first electrode layer (6) and the second electrode layer (7) are arranged on the outer sides of the two alignment film layers (5) opposite to each other at intervals.
The optical waveguide assembly according to claim 6, wherein the liquid crystal pitch of the first coupled-in liquid crystal grating (21) and the first coupled-out liquid crystal grating (22) is 340 nm.
The optical waveguide assembly according to claim 6, wherein the liquid crystal pitch of the second coupled-in liquid crystal grating (31) and the second coupled-out liquid crystal grating (32) is 440 nm.
The optical waveguide assembly according to claim 6, wherein the thickness of the liquid crystal layer (4) does not exceed 2.5 times the liquid crystal pitch.
The optical waveguide assembly according to claim 6, wherein the first coupled-in liquid crystal grating (21), the first coupled-out liquid crystal grating (22), and the second coupled-in liquid crystal grating (31) ) and the second out-coupled liquid crystal grating (32) with a square wave alternating current of 1KHz, and the voltage amplitude is 5V-22V.
The optical waveguide assembly according to claim 6, wherein the first electrode layer (6) and the second electrode layer (7) are made of indium tin oxide (ITO) material.
The optical waveguide assembly according to claim 6, wherein the first coupled-in liquid crystal grating (21), the first coupled-out liquid crystal grating (22), and the second coupled-in liquid crystal grating (31) and the second out-coupling liquid crystal grating (32) respectively further comprises a plurality of spacers, the plurality of spacers are distributed between the two alignment film layers (5) to support the two alignment films layer (5) and maintain and determine the distance between them.
The optical waveguide assembly according to claim 6, wherein the waveguide sheet (1) constitutes a substrate (8) of a liquid crystal grating, the first coupled-in liquid crystal grating (21), the first coupled-out liquid crystal grating (21) The grating (22), the second coupled-in liquid crystal grating (31) and the second coupled-out liquid crystal grating (32) further comprise a protective layer (9), the substrate (8) and the protective layer (9) respectively ) are arranged on the outer sides of the first electrode layer (6) and the second electrode layer (7) opposite to each other at intervals.
The optical waveguide assembly according to claim 13, wherein the protective layer (9) is made of glass material and has a thickness of 0.1 mm˜0.3 mm.
The optical waveguide assembly according to claim 1, wherein the waveguide sheet (1) has a thickness of 0.3-2.5 mm and a refractive index of 1.4-2.2.
The optical waveguide assembly according to claim 1, further comprising a third diffraction unit, the third diffraction unit comprising a third coupled-in liquid crystal grating and a third coupled-out liquid crystal grating, the third coupled-in liquid crystal grating The grating is arranged on a surface of the first coupled-in liquid crystal grating (21) and the waveguide sheet (1) opposite to or on the second coupled-in liquid crystal grating (31) and the waveguide sheet (1) On an opposite surface, the third out-coupling liquid crystal grating is arranged on a surface opposite to the first out-coupling liquid crystal grating (22) and the waveguide sheet (1) or on the second coupling On a surface of the outgoing liquid crystal grating (32) that is opposite to the waveguide sheet (1), the third coupled in liquid crystal grating and the third out coupled liquid crystal grating are arranged to be in the first One direction is grating state;

The third coupled-in liquid crystal grating is used for coupling a third light into the waveguide sheet (1) under the condition of a grating state in the first direction, and the third coupled-out liquid crystal grating is used for in the first Coupling the third light out of the waveguide sheet (1) to the visible area under the condition that the direction is in a grating state, the wavelength of the third light is different from the wavelengths of the first light and the second light ,

Wherein, by alternately applying voltages to each diffractive unit, the first coupled-in liquid crystal grating (21) and the first coupled-out liquid crystal grating (22) of the first diffractive unit (2) or the second diffractive unit (3) ) of the second coupled-in liquid crystal grating (31) and the second coupled-out liquid crystal grating (32) or the third coupled-in liquid crystal grating and the third coupled-out liquid crystal grating of the third diffraction unit are in the grating state in the first direction , so that the first light, the second light and the third light with different wavelengths can be diffracted respectively.
A display device, comprising:

A projector (10), the projector (10) comprising a display chip (101) and a projection lens (102), the display chip (101) being used to control at least a first device that outputs a display image at a certain frequency and in time sequence light and second light, the projection lens (102) is used for projecting the light output by the display chip (101); and

An optical waveguide assembly, the optical waveguide assembly is the optical waveguide assembly according to any one of claims 1 to 16, at least the first coupling into the liquid crystal grating (21) of the first diffraction unit (2) of the optical waveguide assembly and the second coupling-in liquid crystal grating (31) of the second diffractive unit (3) is used to couple the light projected by the projection lens (102) into the waveguide sheet (1) of the optical waveguide assembly, at least The first out-coupling liquid crystal grating (22) of the first diffractive unit (2) of the optical waveguide assembly and the second out-coupling liquid crystal grating (32) of the second diffractive unit (3) are used for coupling into the The light of the waveguide sheet (1) is coupled out of the waveguide sheet (1) to the visible area,

By alternately applying voltage to each diffractive unit, the optical waveguide assembly is controlled at the same frequency as the output of the first light and the second light, and the first diffractive unit (2) or the second diffractive unit (3) is correspondingly controlled. ) is in a grating state in the first direction, so as to diffract the first light and the second light with different wavelengths respectively.
17. The display device according to claim 17, characterized in that the first in-coupling liquid crystal grating (21), the first out-coupling liquid crystal grating (22) and the second diffractive grating are provided to the first diffractive unit (2). The second coupled-in liquid crystal grating (31) and the second coupled-out liquid crystal grating (32) of the unit (3) respectively apply corresponding periodic voltages to control and switch the first coupled-in liquid crystal of the first diffraction unit (2) The grating (21), the first out-coupling liquid crystal grating (22), and the second coupling-in liquid crystal grating (31) and the second out-coupling liquid crystal grating (32) of the second diffraction unit (3) are in the first direction: raster state.
The display device according to claim 17, wherein a frequency at which the display chip (101) outputs the first light and the second light is 60 Hz.