CN113721363A

CN113721363A - Display device and near-to-eye display apparatus

Info

Publication number: CN113721363A
Application number: CN202010450655.4A
Authority: CN
Inventors: 刘娟; 邢志浩; 吕振律
Original assignee: Huawei Technologies Co Ltd; Beijing Institute of Technology BIT
Current assignee: Huawei Technologies Co Ltd; Beijing Institute of Technology BIT
Priority date: 2020-05-25
Filing date: 2020-05-25
Publication date: 2021-11-30
Also published as: WO2021238758A1

Abstract

The embodiment of the application provides a display device and near-to-eye display equipment, and the display device includes: virtual reality stack lens and image engine, this virtual reality stack lens includes: an input coupler, a pupil expander, an output coupler, and an optical waveguide substrate; the input coupler, the pupil expander, and the output coupler are located on the optical waveguide substrate surface. The input coupler, the pupil expander and the output coupler each include a plurality of partitions, and the number of partitions is the same. The one section of the input coupler, the one section of the pupil expander, and the one section of the output coupler are combined with the optical waveguide substrate to form one optical transmission path, the field angles of the plurality of sections of the input coupler are continuous, and the sum of the field angles of the respective sub-field rays coupled into the plurality of sections of the input coupler is not less than the field angle of the total field. The display device enables the visual angle of the virtual and real superposed lenses to be obviously improved.

Description

Display device and near-to-eye display apparatus

Technical Field

The embodiment of the application relates to the technical field of near-eye display, in particular to a display device and near-eye display equipment.

Background

An Augmented Reality (AR) near-eye display system is a wearable display system which enables human eyes to see an external real scene and a virtual scene generated by a computer through a certain optical system. The method aims to integrate a virtual object generated by a computer into a real scene, realize seamless fusion of the real scene and the virtual scene and further realize the enhancement of the real scene. In designing an AR near-eye display system, designing virtual-real superimposed lenses is an important research topic. Virtual-real overlay lenses are used to couple light from a real scene and a light overlay from a computer-generated digital image into the wearer's eye. The existing virtual and real superposition lens design methods comprise a coaxial side-view prism method, an array type semi-permeable membrane waveguide method, a free-form surface method, a geometric waveguide method, a holographic grating waveguide method and the like. The holographic grating waveguide method abandons a complex optical system, can effectively reduce the size and the mass of the system, has the advantages of lightness, smallness and quickness, and becomes a hotspot of research.

The traditional virtual-real superposition lens based on the holographic grating waveguide technology can be composed of an input coupler, a pupil expander, an output coupler and an optical waveguide substrate which plays the role of an optical waveguide on the surface of the optical waveguide substrate. External light is coupled into the lens by the input coupler, expanded by the pupil expander, and directed out of the lens by the output coupler into the wearer's eye.

However, the traditional virtual and real superposition lens based on the holographic grating waveguide technology has a limited field angle, and the visual experience of a wearer is affected.

Disclosure of Invention

The embodiment of the application provides a display device and near-to-eye display equipment, which are used for solving the problems that the visual experience of a wearer is influenced due to the limited field angle of the existing virtual and real superposition lens based on the holographic grating waveguide technology.

In a first aspect, an embodiment of the present application provides a display device, including: virtual reality stack lens and image engine, this virtual reality stack lens includes: an input coupler, a pupil expander, an output coupler, and an optical waveguide substrate.

The input coupler, the pupil expander, and the output coupler are located on the optical waveguide substrate surface.

The input coupler, the pupil expander, and the output coupler each include a plurality of sections.

The optical waveguide substrate is combined with one partition of the input coupler, one partition of the pupil expander and one partition of the output coupler to form one optical transmission channel, the one partition of the input coupler is used for coupling one sub-field of view ray of the total field of view ray from the image engine into the optical waveguide substrate, the one sub-field of view ray is coupled out of the virtual-real superposition lens after being transmitted through the one partition of the pupil expander and the one partition of the output coupler, the field angles of the plurality of partitions of the input coupler are continuous, and the sum of the field angles of the sub-field of view rays coupled into the plurality of partitions of the input coupler is not smaller than the field angle of the total field of view.

In the virtual and real superimposed lens, the input coupler, the pupil expander and the output coupler respectively comprise a plurality of same number of subareas, so long as proper preparation parameters are selected in the virtual and real superimposed lens preparation process, each subarea of the input coupler, the pupil expander and the output coupler can respectively and efficiently diffract incident light within an allowable incident angle range, based on reasonable selection of the allowable incident angle range of each subarea, the field angles of each subarea of the input coupler can be continuous, the sum of the field angles of each sub-field ray coupled into each subarea is not less than that of the total field ray from the image engine, and further the total field ray from the image engine can be completely coupled out of the virtual and real superimposed lens to enter eyes of a wearer, so that the field angle of the virtual and real superimposed lens is remarkably improved, and then make the viewing range of the wearer obtain showing and promoting, greatly promote wearer's visual experience. Meanwhile, an optical waveguide substrate material with higher refractive index does not need to be selected, so that the manufacturing cost of the virtual and real superposed lens is not increased.

In one possible embodiment, the number of sections of the input coupler is the same as the number of sections of the pupil expander and the number of sections of the output coupler, respectively

In one possible design, the plurality of sections of the input coupler are seamlessly spatially contiguous and the total area of the input coupler after splicing covers the output pupil of the image engine.

By arranging the partitions of the input coupler to be spatially and seamlessly adjacent and enabling the total area formed by splicing the partitions to completely cover the output pupil of the image engine, the image light projected from the collimating lens can be coupled into the virtual-real superposition lens to the maximum extent, and the transmission efficiency of the image light is improved.

In one possible design, the allowable incident angle ranges of the plurality of sections of the input coupler are not overlapped in pairs, the diffracted exit angle ranges of the plurality of sections of the input coupler are not overlapped in pairs, the allowable incident angle ranges of the plurality of sections of the pupil expander are not overlapped in pairs, the diffracted exit angle ranges of the plurality of sections of the pupil expander are not overlapped in pairs, the allowable incident angle ranges of the plurality of sections of the output coupler are not overlapped in pairs, and the diffracted exit angle ranges of the plurality of sections of the output coupler are not overlapped in pairs.

When the respective partitions of the input coupler, the pupil expander and the output coupler of the virtual-real superposition lens adopt certain specific spatial layouts, light rays corresponding to a certain specific subfield may first enter other partitions of the pupil expander before reaching the corresponding partition of the pupil expander in the process of being guided to the corresponding partition of the pupil expander by the corresponding partition of the input coupler, and at this time, if the incident angle of the light rays corresponding to the specific subfield falls within the allowable incident angle range of the other partitions, the light rays enter transmission channels of other subfields, so that aliasing crosstalk between subfields is caused. Through the arrangement, aliasing crosstalk between the sub-fields of view can be avoided, and the fact that the image seen by the eyes of the wearer is not abnormal is guaranteed.

In one possible design, one section of the pupil expander is used to perform a first directional pupil expansion of the one subfield of light rays, and one section of the output coupler is used to perform a second directional pupil expansion of the one subfield of light rays. Wherein the first direction is a horizontal direction, and the second direction is a vertical direction; or, the first direction is a vertical direction, and the second direction is a horizontal direction.

By the above arrangement, the pupil expander and the output coupler are made more flexible with respect to the pupil expansion direction of the light rays.

In one possible design, the sections of the input coupler are located on the same side surface of the optical waveguide substrate.

In one possible design, the sections of the pupil expander are located on the same side surface of the optical waveguide substrate.

In one possible design, the sections of the output coupler are located on the same side surface of the optical waveguide substrate.

The input coupler, the pupil expander and the output coupler are respectively arranged on the same side surface of the optical waveguide substrate, so that the virtual-real superposed lens is simpler in structure, and the complexity of the preparation process is reduced.

In one possible design, the input coupler and the output coupler are located on a surface of the optical waveguide substrate on a side facing the image engine when the image engine is on the same side of the virtual-real overlay lens as the wearer's eye.

In one possible design, the input coupler and the output coupler are each transmission gratings.

In one possible design, the input coupler and the output coupler are located on a surface of the optical waveguide substrate on a side facing away from the image engine when the image engine is on the same side of the virtual-real overlay lens as the wearer's eye.

In one possible design, the input coupler and the output coupler are each a reflective grating.

In one possible design, when the image engine and the wearer's eye are on different sides of the virtual-real overlay lens, the input coupler is located on a surface of the optical waveguide substrate on a side facing the image engine, and the output coupler is located on a surface of the optical waveguide substrate on a side facing the wearer's eye.

In one possible design, when the image engine and the wearer's eye are on different sides of the virtual-real overlay lens, the input coupler is located on a surface of the optical waveguide substrate on a side facing away from the image engine, and the output coupler is located on a surface of the optical waveguide substrate on a side facing away from the wearer's eye.

In one possible design, the pupil expander is a reflective grating.

In one possible design, the image engine includes: an image source and a collimating lens; the image source is used for displaying images, and the collimating lens is used for receiving light rays of the images from the image source, collimating the light rays of the images, and guiding the collimated light rays to the input coupler.

In a second aspect, embodiments of the present application provide a near-eye display apparatus including the display device according to the first aspect.

In one possible design, the near-eye display device includes a head-mounted near-eye display device or a glasses-type near-eye display device.

In one possible design, the near-eye display device includes an AR near-eye display device, a VR near-eye display device, or an MR near-eye display device.

Drawings

FIG. 1 is a schematic diagram of a conventional virtual-real stacked lens;

fig. 2 is an exemplary structural diagram of a display device provided in an embodiment of the present application;

FIGS. 3(a), 3(b) and 3(c) are schematic diagrams of an exemplary embodiment of a virtual-real overlay lens in a display device;

FIGS. 4(a), 4(b) and 4(c) are schematic optical path diagrams of total field light from the image engine transmitted to the wearer's eye through the virtual-real overlay lens, respectively;

FIG. 5 is a schematic diagram of three sections of an input-coupler splitting total field of view rays into three sub-field of view rays;

FIG. 6 is another exemplary block diagram of a virtual-real overlay lens;

FIG. 7 is a schematic diagram of the sub-field light coupled in by each section of the input coupler being transmitted through the four light transmission channels.

Detailed Description

The virtual-real superposition lens related to the embodiment of the application is a virtual-real superposition lens based on a holographic grating waveguide technology, and for convenience of description, the virtual-real superposition lens is simply referred to as the virtual-real superposition lens in the embodiment of the application.

Fig. 1 is a view showing an example of the structure of a conventional virtual-real superimposed lens, which is composed of an input coupler, a pupil expander, an output coupler, and a lens substrate itself serving as an optical waveguide, on the surface of the lens substrate, as shown in fig. 1. The virtual-real overlay lens guides and controls the transmission path of the light of the computer-generated digital image outside the lens within the lens and couples into the wearer's eye. And the light rays emitted or reflected by the scenery in the external real physical world can directly penetrate through the lens and enter the eyes of the wearer, so that the visual superposition of the virtual digital image and the real scenery can be completed in the eyes of the wearer.

In the configuration illustrated in fig. 1, the input coupler couples field-of-view light of a digital image incident outside the virtual-real superimposed lens into the lens and leads to a pupil expander that performs pupil expansion of the input field of view in the horizontal direction while leading the light to the output coupler; the output coupler performs vertical direction pupil expansion of the input field of view while directing light out of the lens and into the wearer's eye. In the area of the lens not covered by the input coupler, the output coupler and the pupil expander, light is transmitted in the optical waveguide in a total reflection mode, namely between the upper surface and the lower surface of the lens, so that light energy of an image source entering the lens is reserved to the maximum degree, and the brightness of an image entering human eyes is improved.

Due to the limitations of the refractive index of the lens substrate material and the angular bandwidths of the input coupler, the output coupler and the pupil expander, the field angle of the conventional virtual-real superimposed lens is limited, so that the viewing range of a wearer is limited, and the visual experience of the wearer is affected. Even if the virtual-real superimposed lens is made of a material with a higher refractive index, the improvement effect on the field angle of the virtual-real superimposed lens is not obvious while the virtual-real superimposed lens is made to be expensive.

In consideration of the problem that the visual experience of a wearer is influenced by the limited angle of view of the traditional virtual-real superposed lens, the embodiment of the application performs multi-space partition design on each device of the virtual-real superposed lens, so that the angle of view of the virtual-real superposed lens is remarkably improved, the viewing range of the wearer is remarkably improved, and the visual experience of the wearer is greatly improved.

Fig. 2 is an exemplary structural diagram of a display device according to an embodiment of the present application, and fig. 3(a), fig. 3(b), and fig. 3(c) are respectively an exemplary structural diagram of a virtual-real superimposed lens in the display device. Fig. 3(a) is a front view, fig. 3(b) is a side view, and fig. 3(c) is a plan view. As shown in fig. 2, the display device may include a virtual-real overlay lens and an image engine. The image engine and the eyes of the wearer may be located on the same side of the virtual-real superimposed lens, or may be located on different sides of the virtual-real superimposed lens, and fig. 2, 3(a), 3(b) and 3(c) above illustrate the case where the image engine and the eyes of the wearer are located on the same side of the virtual-real superimposed lens.

Alternatively, as illustrated in FIG. 2, the image engine may include an image source and a collimating lens. Wherein the image source is used to display an image generated by a computer. The image source may be a microdisplay suitable for use in an AR/Virtual Reality (VR)/Mixed Reality (MR) device. Illustratively, the image source may be various organic light-emitting diode (OLED), Liquid Crystal On Silicon (LCOS), Digital Light Processing (DLP) technology based microdisplays that can provide higher image resolution in smaller sizes (e.g., less than 1 inch). The collimating lens receives the light rays of the divergent image from the image source, collimates the light rays of the image, and projects the collimated light rays to the input coupler of the virtual-real superposition lens through the output pupil of the collimating lens. The collimation refers to converting spherical light emitted by each pixel point on the image source into parallel light which is emitted to each direction.

It should be understood that in the embodiments of the present application, the light of the image refers to light emitted by the image source when the image is displayed, and the light of the image may also be referred to as image-corresponding light, or image-corresponding light.

The virtual-real superimposing lens is used to copy the image projected by the collimator lens from its input pupil to its output pupil. The input pupil is an aperture on the input coupler, and the aperture is overlapped with the output pupil of the collimating lens in spatial position, that is, the image light emitted by the image source is collimated by the collimating lens and then coupled into the virtual-real superposition lens through the input pupil of the virtual-real superposition lens. The output pupil is an aperture on the output coupler through which the image rays exit the output coupler of the mirror. The input pupil may also be referred to as the entrance pupil and the output pupil may also be referred to as the exit pupil.

The virtual-real superimposing lens includes an input coupler, a pupil expander, an output coupler, and an optical waveguide substrate. Wherein the input coupler, the pupil expander and the output coupler are all located on the surface of the optical waveguide substrate. The input coupler, the pupil expander and the output coupler each comprise a plurality of sections, and optionally, the number of sections of the input coupler is the same as the number of sections of the pupil coupler and the number of sections of the output coupler, respectively.

The number of the partitions is not limited in the embodiment of the present application, and the number of the partitions may be, for example, 2, 3, 4, or 5. Taking the number of divisions as 3 as an example, it is shown that the number of divisions of the input coupler, the number of divisions of the pupil expander, and the number of divisions of the output coupler are 3 respectively.

A section of the input coupler, a section of the pupil coupler, and a section of the output coupler are combined with the optical waveguide substrate into one optical transmission channel. For example, when the number of divisions is 3, 3 optical transmission channels can be formed in the virtual-real superimposed lens.

Fig. 3(a), 3(b) and 3(c) illustrate examples of structures with 3 partitions, and as illustrated in fig. 3(a), 3(b) and 3(c), the input coupler includes three partitions, 101, 102 and 103, respectively, the pupil expander includes three partitions, 201, 202 and 203, respectively, and the output coupler includes three partitions, 301, 302 and 303, respectively. 101, 201 and 301 are combined with the optical waveguide substrate to form a first optical transmission channel, 102, 202 and 302 are combined with the optical waveguide substrate to form a second optical transmission channel, and 103, 203 and 303 are combined with the optical waveguide substrate to form a third optical transmission channel.

For each light transmission channel, one segment of the input coupler is used to couple in one sub-field of view ray of the total field of view ray from the image engine, which is coupled out of the virtual-real overlay lens after transmission through one segment of the pupil expander and one segment of the output coupler. Taking the above-mentioned fig. 3(a), 3(b) and 3(c) as an example, the partition 101 of the input coupler in the first optical transmission channel is used for coupling in one sub-field light of the total field light from the image engine, coupling the sub-field light into the optical waveguide, and guiding the sub-field light to the partition 201 of the pupil expander, and the partition 201 of the pupil expander performs pupil expansion in the horizontal direction on the sub-field light, and performs pupil expansion in the vertical direction by the partition 301 of the output coupler, and couples the sub-field light into the eye of the wearer. The input coupler segment 102 of the second optical transmission channel is used to couple in one of the total field of view rays from the image engine, to couple in this sub-field of view ray into the optical waveguide and to direct it to the pupil expander segment 202, which pupil expander segment 202 performs pupil expansion in the horizontal direction on the sub-field of view ray, and then performs pupil expansion in the vertical direction by the output coupler segment 302 and couples the sub-field of view ray into the wearer's eye. The third optical transmission channel input coupler segment 103 is for coupling in one of the total field of view rays from the image engine, coupling the subfield rays into the optical waveguide and directing the subfield rays to the pupil expander segment 203, the pupil expander segment 203 performing pupil expansion in the horizontal direction on the subfield rays, and then performing pupil expansion in the vertical direction by the output coupler segment 303 and coupling the subfield rays into the wearer's eye.

Fig. 4(a), 4(b) and 4(c) are schematic diagrams of optical paths of total field light from the image engine to the eyes of the wearer through the virtual-real overlay lens, respectively, wherein fig. 4(a) is a front view, fig. 4(b) is a side view, and fig. 4(c) is a top view. It should be noted that the light path diagrams of fig. 4(a), fig. 4(b), and fig. 4(c) are based on the light path diagrams arranged in the partitions in the structures of fig. 3(a), fig. 3(b), and fig. 3 (c). For convenience of description, the processes of coupling three sub-field light into the input coupler, respectively propagating in the three light transmission channels, and coupling into the eye of the wearer are represented in fig. 4(a), 4(b), and 4(c) by the propagation paths of parallel light ray bundles corresponding to the central points of the three sub-field light rays, respectively. As shown in fig. 4(a), 4(b), and 4(c), the total field of view light projected by the image engine is incident on three partitions of the input coupler, the total field of view light is divided into three sub-field of view lights by the three partitions of the input coupler, and the three sub-field of view lights respectively propagate along the first light transmission channel, the second light transmission channel, and the third light transmission channel in the virtual-real superimposed lens, and are respectively coupled out of the virtual-real superimposed lens from the output coupler to enter the eyes of the wearer.

For the virtual and real superimposed lens, the viewing angles of the sub-viewing field rays coupled into the sub-viewing field rays of the input coupler are continuous, and the sum of the viewing angles of the sub-viewing field rays coupled into the sub-viewing field rays of the input coupler is not less than the viewing angle of the total viewing field rays from the image engine, so that the virtual and real superimposed lens can completely couple the total viewing field rays from the image engine into the eyes of a wearer.

In an alternative, the sum of the field angles of the sub-field of view rays coupled in by the segments of the input coupler is equal to the field angle of the total field of view ray from the image engine.

For example, assuming that the total field angle of the total field rays is 0 to 3 θ °, the field angle of the section 101 of the input coupler may be 0 ° to θ ° at the beginning, the field angle of the section 102 may be θ ° to 2 θ ° at the middle, and the field angle of the section 103 may be 2 θ ° to 3 θ ° at the last. The field angles of the three subareas are continuous, and the sum of the field angles of the sub-field rays coupled in by the three subareas is the total field angle of the total field rays.

It should be noted that the division of the field angles of the respective partitions is only an example, and in a specific implementation process, the division of the field angles may also be performed in other manners, for example, in a non-average division manner.

Alternatively, the preparation parameters can be selected during the preparation process of the input coupler, so that the field angles of the sub-field rays coupled into each subarea of the input coupler are continuous and the sum of the field angles of the sub-field rays coupled into each subarea is the field angle of the total field ray. For example, the input coupler may be a Diffractive Optical Elements (DOE), the input coupler may have selectivity for an incident angle of incident light, and specific preparation parameters are respectively selected for each partition, so that each partition of the input coupler only diffracts the incident light with high efficiency in a specific incident angle range, and the light emitting capability is concentrated in the specific angle range. Incident light falling outside a specific incident angle range propagates in a straight line in the virtual-real superimposed lens and propagates in a total reflection manner when contacting the upper and lower surfaces of the virtual-real superimposed lens. The above-described specific incident angle range may be referred to as an allowable incident angle range, and the specific angle range of outgoing light diffracted by the allowable incident angle range may be referred to as a diffracted outgoing angle range.

Taking the above-mentioned total field angle of the total field ray as 3 θ °, the field angle of the subarea 101 of the input coupler can be from 0 ° to θ ° at the beginning, the field angle of the subarea 102 can be from θ ° to 2 θ at the middle, and the field angle of the subarea 103 can be from 2 θ ° to 3 θ at the last, by selecting the preparation parameters during the preparation of the input coupler. The field angles of the three subareas are continuous, and the sum of the field angles of the sub-field rays coupled in by the three subareas is the total field angle of the total field rays.

Taking the above-mentioned input coupler including three

partitions

101, 102, and 103 as an example, when the field-of-view light of the image engine is incident on the input coupler, the three

partitions

101, 102, and 103 of the input coupler respectively couple in one subfield light of the total field-of-view light, which can be regarded as that the three partitions of the input coupler divide the total field-of-view light into three subfield lights. Fig. 5 is a schematic diagram of three partitions of the input coupler dividing the total field of view into three sub-field of view rays, where, as shown in fig. 5, pixel 1, pixel 2, and pixel 3 respectively represent pixels located at the left, middle, and right portions of the image source, and scattered light emitted by the three pixels is collimated by the collimating lens into parallel beams respectively directed to the front right, and front left, which are respectively represented as beam 1, beam 2, and beam 3 in fig. 5. Taking partition 2 as an example, although the light from pixel 1, pixel 2 and pixel 3 can all illuminate partition 2, alternatively, the total field of view rays of the image source may all strike partition 2, but only the angle of incidence of beam 2 (rays originating from pixel points located in the middle of the image source) falls within the selected allowable range of angles of incidence for partition 2, and thus can be diffracted into a predetermined direction by the device of zone 2, while the range of incidence angles of beam 1 (light originating from a pixel located at the left of the image source) and beam 3 (light originating from a pixel located at the right of the image source) fall outside the range of allowable incidence angles of zone 2, and therefore, the device of zone 2 can be considered to be absent for beam 1 and beam 3, or, the subarea 2 selects the light rays from the central pixel of the image source from the total field light rays incident to the subarea 2, namely, the central subfield light rays are diffracted towards the preset direction. Accordingly, the subarea 1 selects the right part of the sub-visual field from the total visual field light rays incident to the subarea 1 for diffraction, and the subarea 3 selects the left part of the sub-visual field from the total visual field light rays incident to the subarea 3 for diffraction. So that the total field of view rays incident outside the virtual-real superimposed lens are divided into 3 subfields of view by the three divisions of the input coupler and propagate to the 3 divisions of the pupil expander along the respective predetermined diffraction directions and propagation paths, respectively.

Corresponding to the above-mentioned input coupler, the pupil coupler and the output coupler may also be respectively DOE, and the pupil coupler and the output coupler may have selectivity for the incident angle of the incident light, and by selecting specific preparation parameters for each partition, each partition of the pupil coupler and the output coupler can only diffract the incident light in a specific incident angle range with high efficiency.

As an example, each section of the input coupler may be the same as the field angle of the input coupler in the conventional virtual-real superimposed lens illustrated in fig. 1, and assuming that the input coupler includes three sections, and the field angle of each section is 30 °, the virtual-real superimposed lens in the present application can achieve the display effect of the field angle of 90 °, and the expansion of the field angle is three times as large as that of the conventional virtual-real superimposed lens.

In this embodiment, the input coupler, the pupil expander and the output coupler of the virtual-real superimposed lens respectively include a plurality of same number of sections, so long as a proper preparation parameter is selected in the virtual-real superimposed lens preparation process, each section of the input coupler, the pupil expander and the output coupler can respectively and efficiently diffract incident light within an allowable incident angle range, based on a reasonable selection of the allowable incident angle range of each section, the field angles of each section of the input coupler can be made continuous, the sum of the field angles of each sub-field ray coupled into each section is not less than the field angle of the total field ray from the image engine, and further the total field ray from the image engine can be completely coupled out of the virtual-real superimposed lens into the eye of a wearer, so that the field angle of the virtual-real superimposed lens is significantly improved, and then make the viewing range of the wearer obtain showing and promoting, greatly promote wearer's visual experience. Meanwhile, an optical waveguide substrate material with higher refractive index does not need to be selected, so that the manufacturing cost of the virtual and real superposed lens is not increased.

As an alternative embodiment, the sections of the input coupler may be spatially seamless, and the total area of the joined sections completely covers the output pupil of the image engine.

The output pupil of the image engine may refer to the output pupil of the collimating lens in the image engine.

The partitions of the input coupler are arranged to be in seamless adjacency in space, the total area formed by splicing the partitions completely covers the output pupil of the image engine, the image light projected from the collimating lens can be coupled into the virtual-real superposition lens to the maximum extent, and the transmission efficiency of the image light is improved.

In the implementation process, when each partition of the input coupler, the pupil expander and the output coupler of the virtual-real superposition lens adopts some specific spatial layout, light rays corresponding to a specific subfield may first enter other partitions of the pupil expander before reaching the corresponding partition of the pupil expander in the propagation process guided to the corresponding partition of the pupil expander by the corresponding partition of the input coupler, and at this time, if the incident angle of the light rays corresponding to the specific subfield falls within the allowable incident angle range of other partitions, the light rays may enter transmission channels of other subfields, thereby causing aliasing crosstalk between subfields. For example, the light propagation process of the partition space layouts illustrated in fig. 3(a), 3(b), and 3(c) is as shown in fig. 4(a), 4(b), and 4 (c). As can be seen from fig. 4(a), 4(b) and 4(c), the sub-field rays coupled in corresponding to the input coupler section 101 are diffracted and exit, and then enter the

sections

202 and 203 of the pupil expander first in the process of being guided to the corresponding section 201 of the pupil expander, and if the incident angle of the sub-field rays coupled in by the section 101 falls within the allowable incident angle range of the section 202 or/and 203, aliasing crosstalk of the sub-field rays coupled in by the section 101 to other sub-field rays is caused. Accordingly, the sub-field light rays coupled in corresponding to the input coupler section 102, while propagating from the input coupler section 102 to the pupil expander section 202, may cause crosstalk to the sub-field light rays coupled in by the input coupler section 103 via the pupil expander section 203 if the light rays are within the allowable range of angles of incidence of the pupil expander 203.

In order to avoid the above problem, as an alternative embodiment, the allowable incident angle ranges of the respective sections of the input coupler are not overlapped two by two, the diffracted exit angle ranges of the respective sections of the input coupler are not overlapped two by two, and the allowable incident angle ranges of the respective sections of the pupil expander are not overlapped two by two, and the diffracted exit angle ranges of the respective sections of the pupil expander are not overlapped two by two. Meanwhile, the allowable incident angle ranges of all the subareas of the output coupler are not overlapped pairwise, and the diffraction emergent angle ranges of all the subareas of the output coupler are not overlapped pairwise.

Optionally, the allowable incident angle range and the diffraction exit angle range of each partition may be customized by selecting preparation parameters of the diffractive optical device of each partition, so that the allowable incident angle ranges of the partitions of the input coupler are pairwise not overlapped, the diffraction exit angle ranges of the partitions of the input coupler are pairwise not overlapped, the allowable incident angle ranges of the partitions of the pupil expander are pairwise not overlapped, and the diffraction exit angle ranges of the partitions of the pupil expander are pairwise not overlapped.

Taking the spatial layouts of the partitions illustrated in fig. 3(a), 3(b), and 3(c) as an example, the allowable incident angle ranges of the partitions of the input coupler are two-by-two not overlapped, the diffracted exit angle ranges of the partitions of the input coupler are two-by-two not overlapped, the allowable incident angle ranges of the partitions of the pupil expander are two-by-two not overlapped, and the two-by-two diffracted exit angle ranges of the partitions of the pupil expander may specifically include the following information:

1. the diffracted exit rays of section 101 of the input-coupler, as they propagate to section 201 of the pupil expander, fall within the allowable range of angles of incidence for section 201.

2. The diffracted exit rays of the section 102 of the input-coupler, as they propagate to the section 202 of the pupil expander, fall within the allowable range of angles of incidence for the section 202.

3. The diffracted exit rays of section 103 of the input-coupler, as they propagate to section 203 of the pupil expander, fall within the allowable range of angles of incidence for section 203.

4. The diffracted exit rays of the section 101 of the input-coupler, as they propagate to the

sections

202 and 203 of the pupil expander, fall outside the range of allowable angles of incidence for the

sections

202 and 203.

5. The diffracted exit rays of the section 102 of the input-coupler, as they propagate to the individual sections 203 of the pupil expander, fall outside the range of allowable angles of incidence for the sections 203.

The following describes the ray propagation process in another arrangement of the sectional space and describes the sectional range of angles of incidence of the input coupler and the pupil expander.

Fig. 6 is another exemplary structural view of a virtual-real superimposed lens, which is different from the structure illustrated in fig. 3(a), 3(b) and 3(c), in the structure illustrated in fig. 6, the input coupler, the pupil expander and the output coupler each include four sections, and the four sections of the pupil expander are spatially separated in a layout, specifically, on the left and right sides of the input coupler. Specifically, the input coupler includes a section 101, a section 102, a section 103, and a section 104, the pupil expander includes a section 201, a section 202, a section 203, and a section 204, the section 201 and the section 202 are distributed on the left side of the input coupler, and the section 203 and the section 204 are distributed on the right side of the input coupler. The output coupler includes partition 301, partition 302, partition 303, and partition 304.

Based on the structure of fig. 6 described above, four optical transmission channels can be formed. 101, 201 and 301 are combined with the optical waveguide substrate to form a first optical transmission channel, 102, 202 and 302 are combined with the optical waveguide substrate to form a second optical transmission channel, 103, 203 and 303 are combined with the optical waveguide substrate to form a third optical transmission channel, and 104, 204 and 304 are combined with the optical waveguide substrate to form a fourth optical transmission channel.

Fig. 7 is a schematic diagram illustrating the sub-field of view light coupled in by each section of the input coupler being transmitted through the four optical transmission channels, and as shown in fig. 7, the total field of view light from the image engine is divided into four sub-field of view light by the four sections of the input coupler. The sub-field light is coupled in by the section 101 of the input coupler, diffracted to the left into the light guide substrate, expanded horizontally by the section 201 of the pupil expander, and finally coupled out by the section 301 of the output coupler into the eye of the wearer. The section 102 of the input coupler couples in a subfield of light, diffracts into the light guide substrate to the left, performs pupil expansion in the horizontal direction by the section 202 of the pupil expander, and finally is coupled out by the section 302 of the output coupler into the eye of the wearer. The input coupler segment 103 couples in a subfield of light, diffracts into the light guide substrate to the right, performs horizontal pupil expansion by the pupil expander segment 203, and finally is coupled out by the output coupler segment 303 into the wearer's eye. The input coupler segment 104 couples in a subfield of light, diffracts into the light guide substrate to the right, performs horizontal pupil expansion by the pupil expander segment 204, and is finally coupled out by the output coupler segment 304 into the wearer's eye.

The spatial layout of the device illustrated in fig. 7 also has the above-mentioned problem of aliasing crosstalk of the rays in the subfield, and the rays in the subfield that are coupled in by the section 101 of the input coupler may first pass through the second section 202 of the pupil expander while traveling to the left side to the first section 201 of the pupil expander, and further, the rays in the subfield that are coupled in by the section 104 of the input coupler may cross the rays of the rays that are coupled in by the section 103 while traveling to the right side to the section 204 of the pupil expander while passing through the pupil expander 203. Therefore, the above-described method can be used accordingly, so that the allowable incident angle ranges of the respective sections of the input coupler do not overlap two by two, the diffracted exit angle ranges of the respective sections of the input coupler do not overlap two by two, and the allowable incident angle ranges of the respective sections of the pupil expander do not overlap two by two, and the diffracted exit angle ranges of the respective sections of the pupil expander do not overlap two by two. Specifically, the following information may be included:

1. the diffracted exit angle range of the section 101 of the input-coupler falls within the allowed range of angles of incidence of the section 201 of the pupil expander.

2. The diffracted exit angle range of the input-coupler section 102 falls within the allowed range of incidence angles of the pupil expander section 202.

3. The diffracted exit angle range of the section 101 of the input-coupler falls outside the allowed range of incidence angles of the section 202 of the pupil expander.

4. The diffracted exit angle range of the input-coupler section 103 falls within the allowed range of incidence angles of the pupil expander section 203.

5. The diffracted exit angle range of the input-coupler section 104 falls within the allowed range of incidence angles of the pupil expander section 204.

6. The diffracted exit angle range of the input-coupler section 104 falls outside the allowed range of incidence angles of the pupil expander section 203.

As described in the previous embodiments, for each light transmission channel, one segment of the input coupler is used to couple in one subfield light ray of the total field of view light from the image engine, which is coupled out of the virtual-real overlay lens after transmission via one segment of the pupil expander and one segment of the output coupler. Wherein, an optional way of the pupil expander and the output coupler to transmit light comprises: one section of the pupil expander is configured to perform a first directional pupil expansion of one of the sub-field rays and direct the rays to a corresponding section of the output coupler, and a corresponding section of the output coupler is configured to perform a second directional pupil expansion of one of the sub-field rays and direct the rays to the wearer's eye.

The first direction and the second direction may be a horizontal direction or a vertical direction, respectively. Specifically, when the first direction is a horizontal direction, the second direction is a vertical direction. When the first direction is a vertical direction, the second direction is a horizontal direction.

The pupil expander and the output coupler in this application are more flexible with respect to the pupil expansion direction of the light rays than the conventional virtual-real superimposed lens shown in fig. 1.

As an alternative embodiment, the sections of the input coupler may be located on the same side surface of the optical waveguide substrate, the sections of the pupil expander may be located on the same side surface of the optical waveguide substrate, and the sections of the output coupler may be located on the same side surface of the optical waveguide substrate.

For example, as illustrated in fig. 3(a) above, when the image engine and the wearer's eye are on the same side of the virtual-to-real overlay lens, the sections of the input coupler may each be located on a surface of the optical waveguide substrate on the side facing the image engine, the sections of the pupil expander may each be located on a surface of the optical waveguide substrate on the side facing the image engine, and the sections of the output coupler may each be located on a surface of the optical waveguide substrate on the side facing the image engine. Also, the input and output couplers may be transmission gratings and the pupil expander may be a reflection grating.

In this embodiment, the input coupler, the pupil expander, and the output coupler are respectively disposed on the same side surface of the optical waveguide substrate, so that the virtual-real superposed lens has a simpler structure, and the complexity of the manufacturing process is reduced.

As mentioned above, the image engine and the wearer's eyes may be on the same side of the virtual-real overlay lens or on different sides of the virtual-real overlay lens. Accordingly, the input coupler, pupil expander and output coupler may be disposed at different locations on the optical waveguide substrate, as described in more detail below.

For the pupil expander, the pupil expander can be flexibly set whether the image engine is located on the same side or on a different side of the virtual-real superimposed lens from the wearer's eye. In particular, the pupil expander may be located on a side of the optical waveguide substrate facing the image engine or facing away from the image engine when the image engine and the wearer's eye are on the same side of the virtual-real overlay lens, and on a side surface of the optical waveguide substrate facing the image engine or facing away from the image engine when the image engine and the wearer's eye are on different sides of the virtual-real overlay lens. Also, the pupil expander may be a reflective grating.

The following arrangement is possible for the input coupler and the output coupler.

When the image engine is on the same side of the virtual-real overlay lens as the wearer's eye, in one approach, the input and output couplers may both be on the surface of the optical waveguide substrate on the side facing the image engine, and the input and output couplers are both transmissive gratings. Alternatively, the input and output couplers may both be located on a surface of the optical waveguide substrate on a side facing away from the image engine, and the input and output couplers may both be reflective gratings.

When the image engine and the wearer's eye are on different sides of the virtual-real overlay lens, in one approach, the input coupler may be located on a surface of the optical waveguide substrate on the side facing the image engine and the output coupler on a surface of the optical waveguide substrate on the side facing the wearer's eye. Also, the input coupler and the output coupler are each a transmission grating. Alternatively, the input coupler may be located on a surface of the optical waveguide substrate on a side facing away from the image engine and the output coupler on a surface of the optical waveguide substrate on a side facing away from the wearer's eye. And, the input coupler and the output coupler are reflective gratings, respectively.

In the above embodiments, the input coupler, the pupil expander, and the output coupler may be micro-nano structure devices, may be periodic or non-periodic structures, and may be surface gratings, volume gratings, micro-nano photonic devices, micro-nano electronic devices, or the like. Optionally, the input coupler, pupil expander and output coupler are located on the optical waveguide substrate surface and thus may be DOEs. Alternatively, the input coupler, the pupil expander and the output coupler may each be a diffraction grating. A diffraction grating is an optical component that contains a periodic structure that can separate and redirect incident light due to optical diffraction phenomena, the separation and angle changes depending on the characteristics of the diffraction grating. Illustratively, the input coupler, the pupil expander, and the output coupler may be Volume Holographic Gratings (VHG) or Surface Relief Gratings (SRG), respectively. For the two diffraction gratings, the two diffraction gratings can be prepared by selecting proper preparation parameters, and the incident angle of incident light can be selective, namely, only the incident light in a specific incident angle range can be efficiently diffracted, the diffracted emergent light energy is concentrated in the specific angle range, and for the incident light falling outside the specific incident angle range, the incident light can pass through the gratings in a transparent mode.

For VHG, setting of the allowable incident angle range and the diffraction exit angle range of the grating can be achieved by selecting parameters such as specific grating preparation materials (e.g., films made of various silver salt materials, dichromated gelatin, photopolymer or holographic polymer dispersed liquid crystal, etc.), film thickness, object light angle, reference light angle, preparation light wavelength, exposure intensity, etc. at the time of preparation.

For the SRG, the setting of the allowable range of the incident angle and the diffraction exit angle of the grating can be realized by selecting the base band material and controlling the parameters such as the line pitch, the groove depth, the groove profile, the groove filling rate, the groove inclination angle and the like when the base material is processed by the photolithography process.

Both VHG and SRG described above may be implemented as a reflective grating or a transmissive grating. The reflection grating refers to the incident light and the diffraction light which are positioned on the same side of the lens, and the transmission grating refers to the incident light and the diffraction light which are positioned on the two sides of the lens. As described in the foregoing embodiments, the input coupler, the pupil expander, and the output coupler may be selected as transmission gratings or reflection gratings according to whether the image engine and the wearer's eye are located on the same side of the lens, and detailed selection manners are not described herein again.

In addition, alternatively, the optical waveguide substrate in the above embodiments may be made of, for example, glass or optical plastic having good transparency. The optical waveguide substrate has two flat surfaces with good parallelism. The thickness of the substrate should be at least ten times the wavelength of the light propagating therein. Wherein the thickness of the substrate refers to the distance between the two planar surfaces. For example, if the substrate is used to transmit red light at a wavelength of 620 nm, the thickness of the substrate is at least 6200 nm. As an example, the thickness of the optical waveguide substrate of the virtual-real overlay lens is between 0.6 mm and 3 mm. The refractive index of the optical waveguide substrate material may be, for example, 1.5 to 2.0. The higher the refractive index, the larger the achievable field angle.

The embodiment of the present application additionally provides a near-eye display device including the virtual-real superimposed lens described in the above embodiment, where the near-eye display device may be an AR near-eye display device, a VR near-eye display device, or an MR near-eye display device. It should be noted that, when used as a VR near-eye display device, the virtual-real overlay lens can be covered by a non-transparent material, such as cloth, to prevent real world light from entering the virtual-real overlay lens.

In a specific aspect, the near-eye display device may be, for example, a head-mounted near-eye display device or a glasses-type near-eye display device.

Claims

1. A display device, comprising: virtual reality stack lens and image engine, virtual reality stack lens include: an input coupler, a pupil expander, an output coupler, and an optical waveguide substrate,

the input coupler, the pupil expander and the output coupler are located at the optical waveguide substrate surface;

the input coupler, the pupil expander, and the output coupler each comprise a plurality of sections;

a section of the input coupler, a section of the pupil expander, and a section of the output coupler are combined with the optical waveguide substrate to form a light transmission channel, the section of the input coupler is used for coupling one sub-field of view ray of the total field of view ray from the image engine into the optical waveguide substrate, the one sub-field of view ray is coupled out of the virtual-real superposition lens after being transmitted through the section of the pupil expander and the section of the output coupler, the field angles of the plurality of sections of the input coupler are continuous, and the sum of the field angles of the plurality of sections of the input coupler is not less than the field angle of the total field of view ray.

2. The display device of claim 1, wherein the plurality of sections of the input-coupler are spatially seamlessly adjacent and a total stitched area of the plurality of sections of the input-coupler covers an output pupil of the image engine.

3. The display device according to claim 1 or 2, wherein the allowable incident angle ranges of the plurality of division regions of the input coupler are not overlapped two by two, the diffracted exit angle ranges of the plurality of division regions of the input coupler are not overlapped two by two, the allowable incident angle ranges of the plurality of division regions of the pupil expander are not overlapped two by two, the diffracted exit angle ranges of the plurality of division regions of the pupil expander are not overlapped two by two, the allowable incident angle ranges of the plurality of division regions of the output coupler are not overlapped two by two, and the diffracted exit angle ranges of the plurality of division regions of the output coupler are not overlapped two by two.

4. A display device as claimed in any one of claims 1 to 3, characterized in that one section of the pupil expander is arranged to perform a first directional pupil expansion of the one subfield of light rays and one section of the output coupler is arranged to perform a second directional pupil expansion of the one subfield of light rays;

the first direction is a horizontal direction, and the second direction is a vertical direction; alternatively, the first and second electrodes may be,

the first direction is a vertical direction, and the second direction is a horizontal direction.

5. The display device according to any one of claims 1 to 4, wherein the plurality of segments of the input-coupler are located on the same side surface of the optical waveguide substrate.

6. The display device according to any of claims 1-5, wherein the plurality of sections of the pupil expander are located on the same side surface of the optical waveguide substrate.

7. The display device according to any one of claims 1 to 6, wherein the plurality of segments of the output coupler are located on the same side surface of the optical waveguide substrate.

8. The display device according to any one of claims 1 to 7, wherein the input coupler and the output coupler are located on a surface of the optical waveguide substrate facing a side of the image engine when the image engine is on the same side of the virtual-real overlay lens as the wearer's eye.

9. The display device of claim 8, wherein the input-coupler and the output-coupler are each a transmission grating.

10. The display device according to any one of claims 1 to 7, wherein the input coupler and the output coupler are located on a surface of the optical waveguide substrate on a side facing away from the image engine when the image engine is on the same side of the virtual-real overlay lens as the wearer's eye.

11. The display device of claim 10, wherein the input-coupler and the output-coupler are each a reflective grating.

12. The display device according to any one of claims 1 to 7, wherein the input coupler is located on a surface of the optical waveguide substrate on a side facing the image engine and the output coupler is located on a surface of the optical waveguide substrate on a side facing the wearer's eye when the image engine and the wearer's eye are on different sides of the virtual-real overlay lens.

13. The display device of claim 12, wherein the input-coupler and the output-coupler are each a transmission grating.

14. The display device according to any one of claims 1 to 7, wherein the input coupler is located on a surface of the optical waveguide substrate on a side facing away from the image engine and the output coupler is located on a surface of the optical waveguide substrate on a side facing away from the wearer's eyes when the image engine and the wearer's eyes are located on different sides of the virtual-real overlay lens.

15. The display device of claim 14, wherein the input-coupler and the output-coupler are each a reflective grating.

16. The display device according to any of claims 1-15, wherein the pupil expander is a reflective grating.

17. The display device according to any one of claims 1 to 16, wherein the image engine comprises: an image source and a collimating lens;

the image source is used for displaying images, and the collimating lens is used for receiving light rays of the images from the image source, collimating the light rays of the images, and guiding the collimated light rays to the input coupler.

18. A near-eye display apparatus comprising the display device of any one of claims 1-17.

19. The near-eye display device of claim 18, wherein the near-eye display device comprises a head-mounted near-eye display device or a glasses-type near-eye display device.

20. The near-eye display device of claim 18 or 19, wherein the near-eye display device comprises an augmented display AR near-eye display device, a virtual reality VR near-eye display device, or a mixed reality MR near-eye display device.