WO2020248535A1

WO2020248535A1 - Nano waveguide lens and ar display device

Info

Publication number: WO2020248535A1
Application number: PCT/CN2019/122598
Authority: WO
Inventors: 罗明辉; 乔文; 李玲; 李瑞彬; 周振; 熊金艳; 陈林森
Original assignee: 苏州苏大维格科技集团股份有限公司; 苏州大学
Priority date: 2019-06-11
Filing date: 2019-12-03
Publication date: 2020-12-17
Also published as: CN112068233A

Abstract

An AR display device, comprising a nano waveguide lens; the nano waveguide lens comprises a waveguide substrate (21) and a nano-level grating region that is provided on a surface of the waveguide substrate (21) and that is used for diffracting image light information to fulfill the total reflection of the waveguide substrate (21); the grating region comprises a first grating (23) for coupling the image light information such that same enters the waveguide substrate (21), a second grating (25) for changing the direction of the image light information conducted through the waveguide substrate (21), and a third grating (27) for projecting the image light information conducted through the second grating (25) and the waveguide substrate (21) into a space outside of the waveguide lens; the second grating (25) or/and the third grating (27) are provided in a height gradient or duty cycle gradient. The gradient of the grating(s) is used to reduce the brightness gradient, enhance the viewing angle effect, and increase the field of view, exit pupil distance or exit pupil range of the waveguide lens.

Description

Nano waveguide lens and AR display device

This application claims the priority of the Chinese patent application whose application date is June 11, 2019 and the application number is 201910502862.7, the entire content of which is incorporated into this application by reference.

Technical field

The invention relates to the field of display technology, in particular to a nano-waveguide lens and an AR display device.

Background technique

AR (Augmented Reality) technology is a technology that calculates the position and angle of the camera image in real time and adds corresponding images. The goal of this technology is to put the virtual world on the screen and interact with the real world. In order to realize the "seamless" integration of real world information and virtual world information, not only the real world information is displayed, but also the virtual information is displayed at the same time. The two kinds of information complement and superimpose each other, presenting users with a more perceptual effect. Rich new environment. In many fields, such as industrial manufacturing and maintenance, medical, military, entertainment and games, education, etc., it has huge potential application value.

In the AR industry chain, waveguide lenses with both transparency and imaging/light guiding effects are the most critical component for AR hardware implementation. The pupil dilation ability is an important parameter of waveguide lenses, which directly affects the comfort of human eyes and the crowd. Fitness. In AR display technology, brightness uniformity has always been the main reason for limiting the display of large exit pupils. As shown in Figure 1, the light emitted from the light source is incident on the first grating 13 of the waveguide lens 1 in a certain direction, and passes through the first grating. 13 The grating is diffracted, and the diffracted light is transmitted to the second grating along the direction of total reflection in the waveguide 11. The light is totally reflected and diffracted several times in the second grating, and the diffraction efficiency is gradually reduced. It is derived from the third grating 17. In the exit pupil range, the human eye can clearly observe the brightness gradient or sudden change, which directly affects the viewing experience and causes poorer viewing experience. The experience effect.

The foregoing description is to provide general background information and does not necessarily constitute prior art.

Summary of the invention

The purpose of the present invention is to provide a nano-waveguide lens and an AR display device, which utilizes the gradation of the grating to reduce the brightness gradation.

The present invention provides a nano-waveguide lens, comprising a waveguide substrate, a nanoscale grating area arranged on the surface of the waveguide substrate for diffracting image light information to satisfy total reflection of the waveguide substrate, and the grating area includes The first grating for coupling the image light information into the waveguide substrate, the second grating for changing the direction of the image light information conducted through the waveguide substrate, and the second grating for coupling the image light information through the second grating and the waveguide substrate. The image light information transmitted from the waveguide substrate is projected to the third grating in the outer space of the waveguide lens, and the second grating or/and the third grating are set in a manner of height gradient or duty cycle gradient, and the The height or duty ratio of the multiple grating units in the second grating or/and the third grating is used to reduce the brightness gradient.

In one of the embodiments, the gradient of the plurality of grating units is from low to high in height or from small to large duty cycle.

In one of the embodiments, the gradual change of the plurality of grating units in the second grating is from the side close to the first grating to the side away from the first grating, and the third grating is more The gradient of each of the grating units is from a side close to the second grating to a side far from the second grating.

In one of the embodiments, the first grating adopts a height gradation or a gradual duty cycle method, and the gradual change of a plurality of grating units in the first grating approaches the first grating from the side away from the second grating. Gradient on one side of the second grating.

In one of the embodiments, the first grating, the second grating, and the third grating are each a tilted grating, a volume grating, or a rectangular grating.

In one of the embodiments, the first grating, the second grating and the third grating are all nano-scale tilted gratings.

In one of the embodiments, when the gratings adopt the same type of grating unit, the range of the height gradient or the duty cycle gradient is the same.

In one of the embodiments, the height of the grating is gradually changed from 100 to 400 nm, and the duty ratio of the grating is gradually changed from 0.1 to 0.7.

In one of the embodiments, the first grating, the second grating and the third grating are arranged at different positions on the same surface of the waveguide substrate.

The present invention also provides an AR display device including the above-mentioned nano-waveguide lens.

The nano-waveguide lens provided by the present invention realizes the reduction of brightness gradient by adjusting the height or duty ratio of the multiple grating units in the second grating or/and the third grating, thereby avoiding the brightness gradient or sudden change. The bright and dark windows enhance the viewing angle effect and increase the field of view, exit pupil distance or exit pupil range of the nanowaveguide lens.

Description of the drawings

Figure 1 is a schematic diagram of image light information transmission of a conventional waveguide lens;

2 is a schematic diagram of the structure of the nano-waveguide lens of the present invention;

3 is a schematic diagram of image light information transmission of the nano-waveguide lens of the present invention;

4 is a schematic diagram of diffraction of a tilted grating of the present invention;

Fig. 5 is an enlarged view of A in Fig. 3 in the first embodiment of the present invention;

6 is a schematic diagram of the diffraction effect of the highly gradual tilt grating according to the first embodiment of the present invention;

[Corrected according to Rule 91 06.01.2020]
FIG. 7 is an enlarged view of A in FIG. 3 in the second embodiment of the present invention;

[Corrected according to Rule 91 06.01.2020]
FIG. 8 is a schematic diagram of the diffraction effect of the duty-cycle gradient grating according to the second embodiment of the invention.

Detailed ways

The specific embodiments of the present invention will be described in further detail below in conjunction with the drawings and embodiments. The following examples are used to illustrate the present invention, but not to limit the scope of the present invention.

First embodiment

Please refer to Figures 2 to 3, the nano-waveguide lens provided in this embodiment includes a waveguide substrate 21 and a nanoscale grating arranged on the surface of the waveguide substrate 21 for diffracting image light information to satisfy the total reflection of the waveguide substrate 21 Area. The grating area includes a first grating 23 for coupling image light information into the waveguide substrate 21, a second grating 25 for changing the direction of image light information transmitted through the waveguide substrate 21, and a second grating 25 The image light information transmitted by 25 and the waveguide substrate 21 is projected to the third grating 27 in the outer space of the waveguide lens. The second grating 25 or/and the third grating 27 are set in a manner of gradual change in height or duty cycle. The height or duty cycle of multiple grating units in the second grating 25 or/and the third grating 27 is adjusted to reduce Brightness gradient.

The first grating 23, the second grating 25 and the third grating 27 are respectively arranged at different positions on the same side surface of the waveguide substrate 21, and there is a gap between the grating regions. The first grating 23 is set in a manner of a height gradient or a duty cycle gradient. The gradient of the multiple grating units in each grating is from low to high in height or from small to large duty cycle.

Wherein, the gradual change of the multiple grating units in the first grating 23 is from the side away from the second grating to the side close to the second grating; the gradual change of the multiple grating units in the second grating 25 is from the side closer to the first grating. One side of the grating 23 gradually changes to the side away from the first grating 23; the gradual mode of the multiple grating units in the third grating 27 is from the side close to the second grating 25 to the side away from the second grating 25.

Each grating is set in a way that the height is gradual from 100-400nm or the duty cycle is from 0.1-0.7, and each grating is a slanted grating, volume grating or rectangular grating; when different gratings use the same type of grating unit, its grating unit Use the same range of height gradient or duty cycle gradient.

As shown in Figure 4, when incident light enters the inclined grating at an angle α, the diffracted light exits at an angle β. Among them, the diffraction angle depends on the grating period, incident angle, etc., and the grating depth and duty cycle control the diffraction efficiency. By reasonably adjusting the parameters of the tilted grating, it is possible to achieve a certain band of light emitted at a large diffraction angle, so that the first-order diffraction efficiency is maximized at this time, and the zero-order diffraction efficiency is minimized, so as to achieve uniform diffraction efficiency and avoid brightness gradients or sudden changes. The light and dark windows come to affect the viewing angle effect.

During operation, the external image light information is incident from the first grating 23 of the waveguide lens 2 and transmitted to the third grating 27 via the second grating 25. Specifically, when the external image light information is optically coupled to the waveguide lens 2, it first enters the first grating 23, and is diffracted by the grating unit of the first grating 23, and the angle of the diffracted light meets the total reflection of the waveguide substrate 21; the light is transmitted along the total reflection direction, Coupled to the second grating 25, the light is diffracted by the grating unit of the second grating 25 to produce multiple total reflections (the number of total reflections depends on the thickness of the waveguide substrate 21 and the diffraction angle), and is transmitted to the third grating 27, Diffracted by the grating unit of the third grating 27, the output light is focused from the third grating 27 to the retina of the human eye, enabling the human eye to see a realistic virtual stereo image, realizing horizontal and vertical field expansion and real world information and virtual world information "Seamless" integration.

When the waveguide lens transmits image light information and expands its exit pupil, the basic principle that needs to be met is: the output image light information and the input image light information need to meet the parallel condition, so as to expand the entire range of the exit pupil Inside, the image seen will not be distorted. Therefore, when the waveguide lens is designed, the light needs to meet the phase conservation condition, that is, the optical path directions of the first grating 23 and the third grating 27 need to be completely consistent.

In this embodiment, each grating is a nano-scale tilted grating, and the tilted grating adopts a highly gradual manner. In addition to achieving optical path folding and image fusion, through this highly gradual nano-level tilted grating, it also has an imaging function for light at a specific angle of incidence, and at the same time uniformizes the diffraction efficiency, avoiding the brightness gradient or sudden change after the light passes through the gratings The light and dark windows brought by it also increase the field of view, exit pupil distance or exit pupil range of the nanowaveguide lens.

As shown in FIG. 5, in this embodiment, when the inclination angle of the highly gradient grating unit 28 is 30°, the period is 400 nm, and the duty cycle is 0.5, the diffraction efficiency varies with the height of the grating, as shown in FIG. 6, When the grating height changes from 200-400nm, the diffraction efficiency increases from 43% to 95%.

This embodiment also provides an AR display device including the above-mentioned nano-waveguide lens.

Second embodiment

The difference between the nano-waveguide lens provided by the second embodiment of the present invention and the above-mentioned first embodiment is that, in this embodiment, the tilted grating of each grating is the duty-cycle gradient tilted grating unit 29, so as to increase the pupil range. Large and uniform diffraction efficiency, avoiding bright and dark windows caused by brightness gradients or sudden changes.

As shown in Figure 7, when the duty cycle gradient gradient grating unit 29 has a tilt angle of 30°, a period of 400 nm, and a grating height of 300 nm; the diffraction efficiency varies with the grating duty cycle, as shown in Figure 8, when the grating When the space ratio changes from 0.2-0.55, the diffraction efficiency increases from 20% to 96%.

The third embodiment

The difference between the nano-waveguide lens provided by the third embodiment of the present invention and the above-mentioned first and second embodiments is that, in this embodiment, the first and third

grating regions

23 and 27 are both capable of realizing light on the waveguide substrate. 21. Ordinary grating with total reflection. The second grating 25 adopts a highly gradual or gradual duty cycle method to make the diffraction efficiency of the second grating 25 uniform, and avoid the bright and dark windows caused by the brightness gradient or sudden change, so as to enter the third grating 27. The brightness of the light is constant relative to the brightness of the second grating, so as to avoid the sudden change of the brightness of the light output from the third grating relative to the brightness of the light coupled into the first grating, thereby affecting the viewing angle effect.

Fourth embodiment

The difference between the nano-waveguide lens provided by the third embodiment of the present invention and the above-mentioned first and second embodiments is that, in this embodiment, the first and

second gratings

23 and 25 are both capable of realizing light on the waveguide substrate 21 In the general grating area with total reflection, the third grating 27 adopts a highly gradual or gradual duty cycle method to make the diffraction efficiency of the third grating 27 uniform, avoid bright and dark windows caused by brightness gradients or sudden changes, and avoid output from the third grating The sudden change in light brightness affects the viewing angle effect, while increasing the field of view, exit pupil distance or exit pupil range of the nanowaveguide lens.

In the product of the present invention, the grating adopts a highly gradual or duty-cycle gradual manner to realize the uniform diffraction efficiency of the external image light information in the waveguide lens, reduce the brightness gradation, and realize the brightness of the projected image light information is unchanged. Avoid bright and dark windows caused by brightness gradients or sudden changes, enhance the viewing angle effect, and increase the field of view, exit pupil distance or exit pupil range of the nano-waveguide lens; and the grating unit in this grating is simple in design and easy to manufacture; At the same time, a grating unit is used to realize the total reflection of the waveguide after the image light information is diffracted, which reduces the cost and difficulty of manufacturing the waveguide lens.

In the drawings, the sizes and relative sizes of layers and regions are exaggerated for clarity. It should be understood that when an element such as a layer, region, or substrate is referred to as being "formed on," "disposed on," or "on" another element, the element can be directly disposed on the other element, or There may be intermediate elements. In contrast, when an element is referred to as being "directly formed on" or "directly disposed on" another element, there are no intervening elements.

In this article, the terms "upper", "lower", "front", "rear", "left", "right", "top", "bottom", "inner", "outer", "vertical", The orientation or positional relationship indicated by "horizontal" is based on the orientation or positional relationship shown in the drawings, which is only for the clarity of the technical solution and the convenience of description, and therefore cannot be understood as a limitation of the present invention.

The technical features of the above-mentioned embodiments can be combined arbitrarily. In order to make the description concise, all possible combinations of the technical features in the above-mentioned embodiments are not described. However, as long as there is no contradiction in the combination of these technical features, All should be considered as the scope of this specification.

In this article, the terms "include", "include", or any other variations thereof are intended to encompass non-exclusive inclusion, in addition to including those elements listed, but also other elements not explicitly listed.

The above are only specific embodiments of the present invention, but the protection scope of the present invention is not limited thereto. Any person skilled in the art can easily think of changes or substitutions within the technical scope disclosed by the present invention. It should be covered within the protection scope of the present invention. Therefore, the protection scope of the present invention should be subject to the protection scope of the claims.

Claims

A nano-waveguide lens, characterized in that it comprises a waveguide substrate, and a nanoscale grating area arranged on the surface of the waveguide substrate for diffracting image light information to satisfy total reflection of the waveguide substrate, and the grating area includes The first grating used to couple image light information into the waveguide substrate, the second grating used to change the direction of the image light information conducted through the waveguide substrate, and the The image light information conducted by the waveguide substrate is projected to the third grating in the outer space of the waveguide lens, and the second grating or/and the third grating are set in a manner of height gradient or duty cycle gradient, and all The height or duty ratio of the multiple grating units in the second grating or/and the third grating is used to reduce the brightness gradient.
The nano-waveguide lens of claim 1, wherein the gradual change of the multiple grating units is from low to high in height or from small to large duty cycle.
The nano-waveguide lens of claim 2, wherein the gradual change of the plurality of grating units in the second grating is from a side close to the first grating to a side away from the first grating The gradual change of the plurality of grating units in the third grating is from a side close to the second grating to a side away from the second grating.
The nano-waveguide lens of claim 1, wherein the first grating adopts a highly gradual manner or a gradual duty cycle manner, and the gradual manner of a plurality of grating units in the first grating is moved away from the second grating. The side of the grating gradually changes to the side close to the second grating.
The nano-waveguide lens of claim 1, wherein the first grating, the second grating, and the third grating are each a tilted grating, a volume grating, or a rectangular grating.
The nano-waveguide lens of claim 5, wherein the first grating, the second grating and the third grating are all nano-scale tilted gratings.
The nano-waveguide lens of claim 5, wherein when each grating adopts the same type of grating unit, the range of the height gradient or the duty cycle gradient is the same.
7. The nano-waveguide lens of claim 7, wherein the height of the grating is gradually changed from 100 to 400 nm, and the duty ratio of the grating is gradually changed from 0.1 to 0.7.
The nano-waveguide lens of claim 1, wherein the first grating, the second grating and the third grating are arranged at different positions on the same surface of the waveguide substrate.
An AR display device, characterized by comprising the nano-waveguide lens according to any one of claims 1-9.