CN110908125A

CN110908125A - Display device based on waveguide

Info

Publication number: CN110908125A
Application number: CN201911347747.3A
Authority: CN
Inventors: 魏一振; 张卓鹏; 丁毅
Original assignee: Hangzhou Light Grain Technology Co Ltd
Current assignee: Hangzhou Light Grain Technology Co Ltd
Priority date: 2019-12-24
Filing date: 2019-12-24
Publication date: 2020-03-24

Abstract

The invention discloses a display device based on a waveguide, wherein an image projection device is used for projecting image light; the first preset area of the waveguide layer is provided with a coupling-in part for coupling image light into the waveguide layer, and the second preset area of the waveguide layer is provided with a coupling-out part for coupling the image light propagated in the waveguide layer out of the waveguide layer to the viewing side of a user outside the waveguide layer; an optical layer which has an absorption effect on image light and allows other wave bands except the image light to transmit is arranged on the side, far away from the user, of the second preset region of the waveguide layer. The optical layer enables image light leaking from the second preset area of the waveguide layer to the side far away from the user to be absorbed by the optical layer, so that the image light is prevented from leaking to the outside of the display device, and the optical layer does not influence the light of other wave bands except the image light to pass through. Therefore, compared with the prior art, the display device can avoid light from leaking to other directions outside the device, and is beneficial to avoiding the display leakage condition.

Description

Display device based on waveguide

Technical Field

The invention relates to the technical field of virtual reality display, in particular to a display device based on a waveguide.

Background

Augmented Reality (AR) display combines a virtual image obtained by simulation with a real scene to display to a user, so that the user can receive virtual image information and real image information at the same time, thereby achieving augmented reality sensory experience. Augmented reality displays have been widely used in the fields of entertainment, education, industry, military, medical, tourism and other industries.

Traditional augmented reality display system adopts transmission-type optical display mode, in order to realize the augmented reality display scheme of optics transmission-type, has designed the traditional geometric optics system based on semi-transparent semi-reflecting mirror or free curved surface component, utilizes refraction and reflection to realize the stack of virtual image and real scene, however this type of display system who comprises traditional optical element is limited by the total distance of optics, can't accomplish enough frivolously, and it is very far away from daily glasses. In addition, due to the constraint of lagrange invariants, the traditional optical display system has a limited exit pupil size and cannot be adapted to user groups with pupil distances at two ends. Compared to conventional augmented reality display systems, waveguide-based augmented reality display schemes effectively solve the above two problems. After a monochromatic or color image is projected into the waveguide, light is transmitted in the waveguide element through total reflection, so that the thickness of the optical element is effectively reduced, and meanwhile, one or more optical elements on the waveguide are used for controlling the step-by-step output of the image, so that the exit pupil expansion can be realized.

In the prior art, the augmented reality display scheme based on the waveguide adopts a diffractive optical device, such as a surface relief optical waveguide, a holographic optical waveguide, and the like, and also adopts a geometric optical device, such as an array optical waveguide, and the like. The diffraction grating is mainly used for realizing the incidence, the turning and the emergence of light rays, the light ray transmission is realized based on the total reflection principle, the compact structure and the light device can be realized, and the optical device is the most competitive core optical device of the AR display equipment at present.

However, in such an augmented reality display system, after light propagating in the waveguide element is diffracted in the exit grating region, a part of the light exits to enter human eyes, and another part of the light continues to propagate through total reflection.

Disclosure of Invention

The invention aims to provide a display device based on a waveguide, which can avoid light from leaking to other directions outside a device compared with the prior art and is beneficial to avoiding the display leakage condition.

In order to achieve the purpose, the invention provides the following technical scheme:

a waveguide-based display device comprising an image projection device for projecting image light and a waveguide layer;

the first preset area of the waveguide layer is provided with a coupling-in part for coupling image light into the waveguide layer, and the second preset area of the waveguide layer is provided with a coupling-out part for coupling the image light propagated in the waveguide layer out of the waveguide layer to the user viewing side;

and an optical layer which has an absorption effect on image light and allows other wave bands except the image light to transmit is arranged on the side, far away from the user, of the second preset region of the waveguide layer.

Preferably, the optical layer has a coverage area corresponding to a second predetermined region of the waveguide layer.

Preferably, the width of a waveband in which the image projection device generates the image light is 0.1nm to 10nm, the width of an absorption waveband of the optical layer is 0.1nm to 10nm, and the range of the absorption waveband of the optical layer is consistent with the range of the waveband in which the image projection device generates the image light.

Preferably, the optical layer is a narrow-band notch filter, and a narrow-band projection light source is adopted in cooperation with a light source of the image projection device;

or, the image projection device comprises light emitting devices respectively emitting laser of three primary colors, and the central wavelength of the absorption waveband of the optical layer is consistent with the wavelength of the laser emitted by the light emitting devices;

alternatively, the image projection apparatus includes a light emitting device for generating light and a filter element for filtering the light emitted from the light emitting device, the filter element allowing a wavelength range of the light to pass therethrough to coincide with an absorption band range of the optical layer.

Preferably, the optical layer and the waveguide layer have an air space therebetween.

Preferably, the air space between the optical layer and the waveguide layer is 0.001 mm-1 mm.

Preferably, the optical layer overlies the substrate.

Preferably, the optical waveguide device comprises 1 st to nth waveguide layers, wherein the 1 st to nth waveguide layers are sequentially arranged from near to far away from the image projection device, and N is a positive integer greater than or equal to 2;

the first preset area of each waveguide layer is provided with a coupling-in part for coupling image light into the waveguide layer, the second preset area of each waveguide layer is provided with a coupling-out part for coupling the image light propagating in the waveguide layer out to the user viewing side outside the waveguide layer, and the second preset area of each waveguide layer, which is far away from the user viewing side, is provided with an optical layer which has an absorption effect on the image light and allows other wave band light except the image light to transmit;

the coupling-in part of the 1 st waveguide layer is specifically configured to couple image light projected by the image projection device into the 1 st waveguide layer, and the coupling-in part of the ith waveguide layer is specifically configured to couple image light that is not coupled into the previous waveguide layer and is transmitted out from the first preset region of the previous waveguide layer into the ith waveguide layer, i belongs to [2, N ].

Preferably, the coupling-in portion includes an optical element disposed at one side of the first predetermined region of the waveguide layer, for coupling image light into the waveguide layer;

the coupling-out part comprises an optical element which is arranged at one side of the second preset area of the waveguide layer and couples the image light out of the waveguide layer at the side close to the user to watch.

Preferably, the coupling-in portion includes a first optical element disposed on a side of the first predetermined region of the waveguide layer away from the image projection device and a second optical element disposed on a side of the first predetermined region of the waveguide layer close to the image projection device;

image light transmitted from the image projection device or the previous waveguide layer is diffracted at the second optical element of the current waveguide layer to enable diffracted light to enter the current waveguide layer, and the entering light is reflected by the first optical element, diffracted by the second optical element and diffracted by the first optical element in sequence to form diffracted light which is transmitted in the current waveguide layer in a total reflection mode;

or/and the light which does not enter the current waveguide layer when the image light transmitted from the image projection device or the previous waveguide layer passes through the second optical element is diffracted at the first optical element and the diffracted light enters the current waveguide layer and is transmitted in a total reflection mode;

or/and image light transmitted from the image projection device or the previous waveguide layer is diffracted at the second optical element of the current waveguide layer to enable diffracted light to enter the current waveguide layer, the entering light is diffracted by the first optical element to enable the diffracted light to exit to the next waveguide layer, and the exiting light is diffracted at the second optical element of the next waveguide layer to enable the diffracted light to enter the next waveguide layer to be transmitted in a total reflection mode; or/and the light rays which do not enter the next waveguide layer after passing through the second optical element of the next waveguide layer in the emergent light rays are diffracted by the first optical element, the second optical element and the first optical element in sequence to form diffracted light which is transmitted in the next waveguide layer in a total reflection mode;

or/and image light transmitted from the image projection device or the previous waveguide layer is diffracted at the second optical element of the current waveguide layer to enable diffracted light to enter the current waveguide layer, the entering light is reflected by the first optical element and diffracted by the second optical element in sequence to enable the diffracted light to be emitted to the next waveguide layer through the first optical element, and the emergent light is diffracted at the second optical element of the next waveguide layer to enable the diffracted light to enter the next waveguide layer to be transmitted in a total reflection mode; or/and the light which does not enter the latter waveguide layer after passing through the second optical element of the latter waveguide layer in the emergent light is diffracted by the first optical element and diffracted light enters the latter waveguide layer to be transmitted in a total reflection mode;

or/and the light which does not enter the current waveguide layer when the image light transmitted from the image projection device or the previous waveguide layer passes through the second optical element of the current waveguide layer is diffracted by the first optical element and the second optical element in sequence, the diffracted light is emitted to the next waveguide layer through the first optical element, and the emitted light is diffracted by the second optical element of the next waveguide layer and the diffracted light enters the next waveguide layer to be transmitted in a total reflection mode; or/and the light which does not enter the next waveguide layer when the emergent light passes through the second optical element of the next waveguide layer is diffracted by the first optical element, the second optical element and the first optical element in sequence to form diffracted light which is transmitted in the next waveguide layer in a total reflection mode;

or/and the light which does not enter the current waveguide layer when the image light transmitted from the image projection device or the previous waveguide layer passes through the second optical element of the current waveguide layer is diffracted by the first optical element, reflected by the second optical element and diffracted by the first optical element in sequence to be emitted to the next waveguide layer, and the emitted light is diffracted by the second optical element of the next waveguide layer to be transmitted in a total reflection mode when entering the next waveguide layer; or/and the light which does not enter the latter waveguide layer when the emergent light passes through the second optical element of the latter waveguide layer is diffracted by the first optical element and diffracted light enters the latter waveguide layer to be transmitted in a total reflection mode.

Preferably, the first optical element of each of the waveguide layers is a reflective optical element based on the diffraction principle, or the first optical element of each of the waveguide layers is a transmissive optical element based on the diffraction principle; or the first optical elements of a plurality of waveguide layers from the 1 st to the Nth waveguide layers are reflection type optical elements based on the diffraction principle, and the first optical elements of other waveguide layers are transmission type optical elements based on the diffraction principle;

the second optical element of each waveguide layer is a reflective optical element based on the diffraction principle, or the second optical element of each waveguide layer is a transmissive optical element based on the diffraction principle; or the second optical elements of a plurality of the 1 st to Nth waveguide layers are reflective optical elements based on the diffraction principle, and the second optical elements of other waveguide layers are transmissive optical elements based on the diffraction principle.

Preferably, projections of the second preset regions of the waveguide layers along the arrangement direction of the waveguide layers do not overlap each other, or projections of the second preset regions of the waveguide layers along the arrangement direction of the waveguide layers partially overlap.

According to the technical scheme, the display device based on the waveguide comprises the image projection device and the waveguide layer, wherein the image projection device is used for projecting image light, the first preset area of the waveguide layer is provided with the coupling-in part used for coupling the image light into the waveguide layer, the second preset area of the waveguide layer is provided with the coupling-out part used for coupling the image light propagated in the waveguide layer out of the user viewing side outside the waveguide layer, and the image light coupled out by the waveguide layer enters the eyes of the user, so that the display of a virtual image is realized. Wherein keep away from user viewing side at the second of waveguide layer and be provided with the optical layer that has the absorption effect and allow other wave band light except that image light to transmit in the second preset area of waveguide layer, make the image light who leaks to keeping away from user viewing side from the second preset area of waveguide layer can be absorbed by the optical layer, avoided this part of image light to leak outside display device, and the optical layer does not influence other wave band light except that image light and passes through, thereby do not influence outside light transmission to user's eyes formation of image again when having avoided light to leak outside display device. Therefore, compared with the prior art, the display device can avoid light from leaking to other directions outside the device, is beneficial to avoiding the display leakage condition, and effectively protects the privacy of users.

Drawings

In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly described below, it is obvious that the drawings in the following description are only some embodiments of the present invention, and for those skilled in the art, other drawings can be obtained according to the drawings without creative efforts.

FIG. 1 is a schematic diagram of a conventional display device using a waveguide to generate leakage light;

FIG. 2 is a schematic view of a waveguide-based display device according to embodiment 1 of the present invention;

FIG. 3 is a schematic diagram of an optical path of the display device shown in FIG. 2;

FIG. 4 is a schematic view of an optical path without an optical layer disposed in a second predetermined region of the waveguide layer;

FIG. 5 is a graph of the transmission spectrum of an optical layer in one embodiment;

FIG. 6 is a schematic view of a waveguide-based display device according to embodiment 2 of the present invention;

FIG. 7 is a schematic diagram of the optical path of a prior art waveguide-based display device;

fig. 8 is a schematic diagram of an optical path in which a display device according to embodiment 2 of the present invention includes 2 waveguide layers;

FIG. 9 is a schematic view of a waveguide-based display device according to embodiment 3 of the present invention;

fig. 10 to 19 are schematic diagrams of ten kinds of optical paths existing in the display device according to embodiment 3 of the present invention in sequence;

fig. 20 is a schematic diagram showing an optical path in which the first optical element of the waveguide layer is a reflection type optical element based on the diffraction principle in the display device according to embodiment 3 of the present invention;

fig. 21 is a schematic diagram of an optical path of a transmissive optical element based on the diffraction principle, which is a second optical element of the waveguide layer in the display device according to embodiment 3 of the present invention.

Detailed Description

In order to make those skilled in the art better understand the technical solution of the present invention, the technical solution in the embodiment of the present invention will be clearly and completely described below with reference to the drawings in the embodiment of the present invention, and it is obvious that the described embodiment is only a part of the embodiment of the present invention, and not all embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

Referring to fig. 1, fig. 1 is a schematic diagram of a conventional display device using a waveguide for generating leakage light, where when a user wears the display device, the leakage light generated by the display device is emitted in a direction away from eyes of the user, and the portion of the leakage light is transmitted to other directions outside the device, so that an image can be seen from the outside, thereby causing a display leakage situation.

In view of this, embodiments of the present invention provide a waveguide-based display device, including an image projection device and a waveguide layer, where the image projection device is used to project image light;

The waveguide layer is a waveguide structure capable of guiding light to propagate. The image projection device projects image light to the waveguide layer, the coupling-in part of the waveguide layer couples the image light projected by the image projection device into the waveguide layer, the coupling-out part arranged in the second preset area of the waveguide layer couples the image light propagated in the waveguide layer out to the watching side of a user outside the waveguide layer, and the image light coupled out by the waveguide layer enters eyes of the user, so that the display of a virtual image is realized. Wherein, keep away from user viewing side at the second of waveguide layer and predetermine the region and be provided with the optical layer that has the absorption effect and allow other wave band light except that image light to transmit, make from the predetermined region of waveguide layer second to watch the image light that one side leaked to keeping away from the user and can be absorbed by the optical layer, avoided this part of image light to leak outside display device, and the optical layer does not influence other wave band light except that image light to pass through, thereby do not influence outside light transmission to user's eyes formation of image again when having avoided light to leak outside display device. Therefore, compared with the prior art, the display device can avoid light from leaking to other directions outside the device, is beneficial to avoiding the display leakage condition, and effectively protects the privacy of users and the information safety.

The waveguide-based display device is described in detail below with reference to the figures and the detailed description. Referring to fig. 2, fig. 2 is a schematic diagram of a waveguide-based display device according to embodiment 1, and it can be seen that the display device includes an image projection device 10 and a waveguide layer 11. The image projection device 10 is used for projecting image light. The image projector 10 may be a projector, and may be any type of projector, and is within the scope of the present invention.

A coupling-in section for coupling image light into the waveguide layer 11 is provided in a first predetermined region of the waveguide layer 11, and a coupling-out section for coupling out the image light propagating in the waveguide layer 11 to a user viewing side outside the waveguide layer 11 is provided in a second predetermined region of the waveguide layer 11. The image light generated by the image projecting device 10 is coupled into the waveguide layer 11 through the coupling-in portion, the coupled-in image light propagates in the waveguide layer 11 in a total reflection manner, the image light propagates in the turning region of the waveguide layer 11 in a total reflection manner, and is coupled out by the coupling-out portion when propagating to the second preset region, and the coupled-out image light enters the eyes of the user to realize virtual image display.

Alternatively, the coupling-in portion may be an optical element based on the diffraction principle, and specifically, referring to fig. 2 and fig. 3, fig. 3 is a schematic diagram of an optical path of the display device shown in fig. 2, the coupling-in portion includes an optical element 110 disposed at one side of the first predetermined region of the waveguide layer 11 and coupling image light into the waveguide layer 11, the image light incident to the waveguide layer 11 is diffracted at the optical element 110 of the waveguide layer coupling-in portion, and the generated diffracted light is coupled into the waveguide layer 11. Alternatively, as shown in fig. 2 and 3, the optical element 110 of the coupling-in portion may be disposed on the side of the waveguide layer 11 away from the image projection device 10, or the optical element of the coupling-in portion may be disposed on the side of the waveguide layer close to the image projection device.

The outcoupling portion may be an optical element based on the diffraction principle. Referring to fig. 2 and 3, the coupling-out portion includes an optical element 111 disposed at a second predetermined region side of the waveguide layer 11 and coupling the image light out of the waveguide layer 11 near a user viewing side, the image light propagating in the waveguide layer 11 is diffracted by the optical element 111 at the coupling-out portion of the waveguide layer 11, and the generated diffracted light is coupled out of the waveguide layer 11. Alternatively, as shown in fig. 2 and 3, the optical element 111 of the outcoupling portion may be disposed on the side of the waveguide layer 11 facing away from the user's view. Or in other embodiments the optical elements of the outcoupling portion may be arranged at the side of the waveguide layer closer to the viewing side of the user.

Referring to fig. 4, fig. 4 is a schematic diagram of a light path without an optical layer disposed in the second predetermined region of the waveguide layer, and it can be seen from the diagram that when light reaches the second predetermined region of the waveguide layer 11, a part of the light is coupled out of the waveguide layer to a side close to the user viewing side, and a part of the light leaks out of the waveguide layer to a side far away from the user viewing side. In the display device of the present embodiment, referring to fig. 3, an optical layer 112 is disposed on a side of the second predetermined region of the waveguide layer 11 away from the user, and the optical layer 112 absorbs the image light and allows light of other bands except the image light to transmit. The optical layer 112 can absorb the image light emitted from the second predetermined region of the waveguide layer 11 to the side away from the user viewing side, i.e. the leakage light, so as to prevent the image light from leaking to the side of the waveguide layer away from the user viewing side and leaking to the outside of the display device. Also, the optical layer 112 allows light of other wavelength bands than the image light to transmit, so that the light of the external scene does not enter the eyes of the user and the user can not watch the external real scene.

Preferably, the coverage of the optical layer 112 is consistent with the second preset region of the waveguide layer 11, that is, the second preset region of the waveguide layer 11 is completely covered by the optical layer 112, so that light leaking to the side far away from the user viewing side in the second preset region of the waveguide layer can be absorbed by the optical layer 112, thereby effectively protecting the privacy of the user and greatly improving the information security of the user.

Optionally, the width of a waveband for generating the image light by the image projection device 10 is 0.1nm to 10nm, the width of an absorption waveband of the optical layer 112 is 0.1nm to 10nm, and the range of the absorption waveband of the optical layer 112 is consistent with the range of the waveband for generating the image light by the image projection device 10, that is, the absorption peak of the optical layer 112 corresponds to the wavelength range of the image light generated by the image projection device. The image projection device 10 is configured to use a narrow-band light source, the corresponding optical layer 112 can use a narrow-band filtering optical layer, and the absorption waveband of the optical layer 112 is narrow, so that the optical layer can not influence the light of the external scene to transmit to the eyes of the user as much as possible, and the user can not influence the viewing of the external real scene.

Optionally, the optical layer 112 is a narrow-band notch filter, a narrow-band projection light source is used in cooperation with the light source of the image projection apparatus 10, an absorption peak of the optical layer 112 corresponds to a wavelength of the narrow-band light source, only light rays with the wavelength corresponding to the light source are absorbed, light rays with other wavelengths are transmitted, light rays of a projected image are effectively prevented from being leaked out, and privacy of a user and information security are protected. The optical layer 112 also absorbs the corresponding wavelength light in the external light, but the wavelength range is narrow, only a few nanometers, and the transmission of other external light to human eyes is not affected, i.e. the user is not affected to watch the external real scene.

Alternatively, the image projection apparatus 10 may include light emitting devices that emit laser light of three primary colors, respectively, and the central wavelength of the absorption band of the optical layer 112 coincides with the wavelength of the laser light emitted from the light emitting devices. Specifically, the image projection apparatus 10 may include light emitting devices that respectively emit red laser light, green laser light, and blue laser light, the optical layer includes three narrow-band notch absorption peaks, and a central wavelength of each absorption peak is respectively consistent with wavelengths of the laser light emitted by the three light emitting devices, please refer to fig. 5, fig. 5 is a transmission spectrum diagram of the optical layer in an embodiment, it can be seen that the optical layer includes three absorption bands, central wavelengths of each absorption band are respectively blue light, green light, and red light, and light of other bands can pass through the optical layer, and the red light, the green light, and the blue light are absorbed. The laser light generated by the light emitting device has a narrow wavelength band, so that the image projection apparatus generates image light in a narrow wavelength band range.

Alternatively, the image projection device 10 may include a light emitting device for generating light and a filter element for filtering light emitted from the light emitting device, the filter element allowing a wavelength range of light to be coincident with an absorption band range of the optical layer, so that a band range of image light generated by the image projection device is coincident with an absorption band range of the optical layer 112. Alternatively, the light emitting device may be an LED, or may be another kind of light emitting device.

Preferably, an air gap may be provided between the optical layer and the waveguide layer, so as to ensure that the total reflection condition of the waveguide layer is not destroyed, so as not to affect the light propagation in the waveguide layer, and thus not to affect the human eye receiving the image light to view the image. Specifically, in the case that an optical element for coupling image light propagating in the waveguide layer out of the waveguide layer is disposed on a side of the second predetermined region of the waveguide layer away from the user, an air gap is provided between the optical element and an outer surface of the optical element. Specifically, the air gap between the optical layer and the waveguide layer may be 0.001mm to 1 mm.

Alternatively, the optical layer 112 may be coated on a substrate, the optical layer being disposed with the substrate on the side of the waveguiding layer 11 facing away from the user's view. The substrate may be a glass substrate or a plastic substrate and the optical layer 112 may be a film-coated layer.

Referring to fig. 6, fig. 6 is a schematic diagram of a waveguide-based display device according to embodiment 2, which shows that the display device includes an

image projection device

20 and 1 st to nth waveguide layers 21, where N is a positive integer greater than or equal to 2. The image projection device 20 is used for projecting image light. The image projector 20 may be a projector, and may be any type of projector, and is within the scope of the present invention.

The 1 st to nth waveguide layers 21 are sequentially arranged from near to far from the image projecting device 20, a first preset region of each waveguide layer 21 is provided with an incoupling portion for coupling image light into the waveguide layer 21, referring to fig. 6, the incoupling portion may specifically include an optical element 210 disposed at a side of the first preset region of the waveguide layer 21 away from the image projecting device 20, the optical element 210 is configured to couple the image light into the waveguide layer 21, the image light propagated from the image projecting device 20 or the previous waveguide layer 21 is diffracted by the optical element 210 of the current waveguide layer, and the generated diffracted light is coupled into the current waveguide layer 21 and propagates in a total reflection manner. The coupling-in part of the 1 st waveguide layer is used for coupling the image light projected by the image projection device 20 into the 1 st waveguide layer, the coupling-in part of the ith waveguide layer is used for coupling the image light which is not coupled into the previous waveguide layer and is transmitted out from the first preset region of the previous waveguide layer into the ith waveguide layer, and i belongs to [2, N ].

Referring to fig. 7, fig. 7 is a schematic diagram of a light path of a conventional waveguide-based display device, where the diffraction efficiency of the coupling-in element 61 is set to 30%, and in the case of no absorption, the energy of the incident light 1 is 100%, the light 2 is 0-order emergent light of the incident light 1, the energy is 70%, and the light 3 is diffracted light of the incident light 1, and the energy is 30%; ray 4 is the diffracted light of ray 3, and the energy is 9%; the light 5 is coupled into the waveguide layer 60 by the incoupling elements 61, and the light with 21% energy enters the waveguide layer 60 for transmission, i.e. 21% of the energy is coupled into the waveguide layer, and the incoupling efficiency of the waveguide-based display device is 21%. This embodiment display device is through setting up a plurality of waveguide layers, the image light that is not coupled into in the waveguide layer by preceding waveguide layer can be coupled again by the next waveguide layer, for example the display device shown in fig. 7, 0 level outgoing light 2 that transmits out the waveguide layer and the light that couples into the waveguide layer diffract through the incoupling component once more and outcouple the light 4 outside the waveguide layer, this embodiment display device can couple this part of light again through the waveguide layer at the back, therefore, it is visible, this display device compares with prior art, can reduce light and reveal, improve the light energy utilization ratio, promote display device's performance and user experience.

Referring to fig. 8, fig. 8 is a schematic diagram of an optical path of the waveguide-based display device of the present embodiment including 2 waveguide layers, wherein the display device includes 2 waveguide layers, i.e., a 1 st waveguide layer 31 and a 2 nd waveguide layer 32, as an example. As shown, the coupling-in portion 310 is disposed on the first predetermined region side of the 1 st waveguide layer 31, and the coupling-in portion 320 is disposed on the first predetermined region side of the 2 nd waveguide layer 32, where the diffraction efficiency of each coupling-in portion optical element is 30%. Ray 1 is incident image light with energy of 100%, and ray 2 is 0-level emergent light of ray 1 with energy of 70%; ray 3 is the diffracted light of ray 1, with energy 30%; ray 4 is the diffracted light of ray 3, and the energy is 9%; ray 5 is 0 th order light of ray 3 at the incoupling portion 310 and has 21% energy. Ray 6 is the diffracted light of ray 2 at the incoupling portion 320 of the 2 nd waveguide layer 32, and has an energy of 21%; ray 7 is 0 th order light of ray 2 at the incoupling portion 320, with energy of 49%; the light ray 8 is the diffracted light of the light ray 6 at the coupling-in part 320, and the energy is 6.3%; ray 9 is 0 th order light of ray 6 at incoupling portion 320, with an energy of 14.7%; the light 10 is the diffracted light of the light 4 at the coupling-in part 320, and the energy is 2.7%; ray 11 is 0 th order light of ray 4 at the incoupling portion 320, and has an energy of 6.3%. Therefore, the 1 st waveguide layer 31 and the 2 nd waveguide layer 32 have a coupling-in efficiency of 38.4%, that is, 38.4% of energy is coupled into the waveguide layer for transmission. It can be seen that compared with the display device shown in fig. 7, the waveguide efficiency of the display device of the present embodiment is improved by 83%, and the light energy utilization rate is greatly improved.

In the display devices shown in fig. 6 and 8, taking the example that the optical element included in the coupling-in portion is disposed on the side of the first predetermined region of the waveguide layer 21 away from the image projecting device 20, alternatively, in the present display device, the optical element included in the coupling-in portion for coupling image light into the waveguide layer may be disposed on the side of the first predetermined region of the waveguide layer close to the image projecting device, and it is within the scope of the present invention.

In this embodiment, the incoupling portion of each waveguide layer may adopt a reflective optical element based on the diffraction principle, or the incoupling portion of each waveguide layer may adopt a transmissive optical element based on the diffraction principle. Alternatively, the coupling-in portions of the 1 st to nth waveguide layers are reflective optical elements based on the diffraction principle, and the coupling-in portions of the other waveguide layers are transmissive optical elements based on the diffraction principle, which are all within the protection scope of the present invention. The incoupling optical element may be a grating, and the grating structures of the respective waveguide layer incoupling gratings may or may not be identical.

Referring to fig. 6, the second predetermined region of each waveguide layer 21 is provided with an out-coupling portion 211 for coupling the image light propagating in the waveguide layer 21 out of the waveguide layer 21 to the viewing side of a user, the image light coupled into the waveguide layer 21 propagates in the waveguide layer in a total reflection manner, the image light propagates in the turning region of the waveguide layer in a total reflection manner, and is coupled out by the out-coupling portion 211 when propagating to the second predetermined region, and the image light coupled out by each waveguide layer 21 enters the eyes of the user to be displayed. Wherein the outcoupling portion 211 may be an optical element based on the diffraction principle. In this embodiment, referring to fig. 6, the optical element 211 of the coupling-out section may be disposed on a side of the waveguide layer 21 away from the user viewing side. Or in other embodiments the optical elements of the outcoupling portion may be arranged at the side of the waveguide layer closer to the viewing side of the user.

Further, referring to fig. 6 and 8, an optical layer 212 is disposed on a side of the second predetermined region of each waveguide layer 21 away from the user viewing side, the optical layer absorbing image light and allowing light of other wavelength bands except for the image light to transmit therethrough. For the specific implementation of the optical layer 212, reference may be made to the description of the previous embodiment, which is not repeated in this embodiment.

Preferably, the projections of the second predetermined regions of the waveguide layers 21 along the arrangement direction of the waveguide layers 21 do not overlap each other, or the projections of the second predetermined regions of the waveguide layers 21 along the arrangement direction of the waveguide layers partially overlap, so as to avoid the second predetermined regions of the waveguide layers from completely overlapping, and if the second predetermined regions of the two waveguide layers completely overlap, the light coupled out by the next waveguide layer is incident on the coupling-out optical element in the second predetermined region of the previous waveguide layer and is re-coupled into the waveguide layer, so that the light is coupled out as much as possible by the above arrangement, and the light is coupled out as much as possible to enter the eyes of the user, thereby improving the waveguide efficiency and the light energy utilization ratio.

Referring to fig. 9, fig. 9 is a schematic diagram of a waveguide-based display device according to embodiment 3, in which the display device includes an

image projection device

40 and 1 st to nth waveguide layers 41, where N is a positive integer greater than or equal to 2. The image projection device 40 is used for projecting image light. The image projection device can be a projector, and can be various types of projectors, and the invention is within the protection scope of the invention.

The 1 st to nth waveguide layers 41 are sequentially arranged from near to far from the image projecting device 40, a coupling-in portion for coupling image light into the waveguide layer 41 is disposed in a first preset region of each waveguide layer 41, and the coupling-in portion specifically includes a first optical element 410 disposed on a side of the first preset region of the waveguide layer 41 far from the image projecting device 40 and a second optical element 411 disposed on a side of the first preset region of the waveguide layer 41 close to the image projecting device 40.

Preferably, the coupling-in portion of the waveguide layer 41 may implement: the light rays which do not enter the front waveguide layer 41 when passing through the second optical element, of the image light rays propagating from the image projecting device 40 or the front waveguide layer 41 are diffracted at the first optical element and diffracted light rays propagate as total reflection in the front waveguide layer 41.

Further preferably, the coupling-in portion of the waveguide layer 41 may implement: the image light propagated from the image projecting device 40 or the previous waveguide layer 41 is diffracted by the second optical element of the current waveguide layer to cause diffracted light to enter the current waveguide layer 41, and the entering light is reflected by the first optical element, diffracted by the second optical element, and diffracted by the first optical element in this order to propagate as total reflection in the current waveguide layer 41.

Further preferably, the coupling-in portion of the waveguide layer 41 may implement: the image light propagated from the image projecting device 40 or the front waveguide layer 41 is diffracted at the second optical element of the front waveguide layer 41 to make the diffracted light enter into the front waveguide layer 41, the entering light is diffracted by the first optical element to make the diffracted light exit to the rear waveguide layer 41, the exiting light is diffracted at the second optical element of the rear waveguide layer 41 to make the diffracted light enter into the rear waveguide layer 41 to be propagated in a total reflection manner; or/and the light rays which do not enter the rear waveguide layer 41 through the second optical element of the rear waveguide layer 41 in the emergent light rays sequentially pass through the diffraction of the first optical element, the diffraction of the second optical element and the diffraction of the first optical element to form diffracted light which is propagated in the rear waveguide layer in a total reflection mode.

Further preferably, the coupling-in portion of the waveguide layer 41 may implement: the image light transmitted from the image projecting device 40 or the front waveguide layer 41 is diffracted at the second optical element of the front waveguide layer 41 to make the diffracted light enter the front waveguide layer 41, the entering light is reflected by the first optical element and diffracted by the second optical element in sequence, the diffracted light is emitted to the rear waveguide layer 41 through the first optical element, the emergent light is diffracted at the second optical element of the rear waveguide layer 41 to make the diffracted light enter the rear waveguide layer 41 to be transmitted in a total reflection mode; or/and the light ray which does not enter the rear waveguide layer 41 through the second optical element of the rear waveguide layer 41 in the emergent light ray is diffracted by the first optical element and diffracted light enters the rear waveguide layer 41 to propagate in a total reflection mode.

Further preferably, the coupling-in portion of the waveguide layer 41 may implement: the light which does not enter the current waveguide layer 41 when the image light transmitted from the image projecting device 40 or the previous waveguide layer 41 passes through the second optical element of the current waveguide layer 41 passes through the diffraction of the first optical element and the diffraction of the second optical element in sequence, the diffracted light exits to the next waveguide layer 41 through the first optical element, the exiting light is diffracted by the second optical element of the next waveguide layer 41, and the diffracted light enters the next waveguide layer 41 and is transmitted in a total reflection mode; or/and the light rays which do not enter the rear waveguide layer 41 when passing through the second optical element of the rear waveguide layer 41 in the emergent light rays are diffracted by the first optical element, the second optical element and the first optical element in sequence to form diffracted light which is propagated in the rear waveguide layer 41 in a total reflection mode.

Further preferably, the coupling-in portion of the waveguide layer 41 may implement: the light which does not enter the current waveguide layer 41 when the image light transmitted from the image projecting device 40 or the previous waveguide layer 41 passes through the second optical element of the current waveguide layer 41 passes through the diffraction of the first optical element, the reflection of the second optical element, the diffraction of the first optical element and the exit of the diffracted light to the next waveguide layer 41 in sequence, the exit light is diffracted by the second optical element of the next waveguide layer 41 and the diffracted light enters the next waveguide layer 41 to be transmitted in a total reflection mode; or/and the light which does not enter the rear waveguide layer 41 when passing through the second optical element of the rear waveguide layer 41 in the emergent light is diffracted by the first optical element and diffracted light enters the rear waveguide layer 41 to propagate in a total reflection mode.

In a specific implementation manner of the display device in this embodiment, any one or any several of the above various propagation light paths may exist in each waveguide layer of the display device at the same time, so as to implement waveguide transmission of image light, thereby greatly improving waveguide efficiency and improving light energy utilization ratio compared with the existing waveguide-based display device.

For example, in the display device of this embodiment, if the second optical element of each waveguide layer uses a transmissive optical element based on the diffraction principle, and the first optical element of each waveguide layer uses a reflective optical element based on the diffraction principle, at least ten optical paths are simultaneously propagated in each waveguide layer of the display device (regardless of the situation that the light transmission energy is low). The ten optical paths existing in the display device of this embodiment are described in a one-to-one manner with reference to the schematic diagram of the optical paths, where the display device includes 2 waveguide layers, that is, a 1 st waveguide layer 51 and a 2 nd waveguide layer 52, as an example, a first optical element 510 is disposed on a side of a first preset region of the 1 st waveguide layer 51 away from the image projection device, and a first optical element 520 is disposed on a side of the first preset region of the 2 nd waveguide layer 52 away from the image projection device.

Referring to fig. 10, fig. 10 is a schematic diagram of a first optical path of the display device of the present embodiment, and the optical path in the 1 st waveguide layer 51 is: the image light propagating through the image projector or the preceding waveguide layer is diffracted by the second optical element 511 of the 1 st waveguide layer 51 to cause diffracted light to enter the 1 st waveguide layer 51, and the entering light is reflected by the first optical element 510, diffracted by the second optical element 511, and diffracted light caused by the first optical element 510 in this order to propagate through the 1 st waveguide layer 51 as total reflection. The optical path within the 2 nd waveguide layer 52 is: when image light passes through the second optical element 511 of the 1 st waveguide layer 51, light that does not enter the 1 st waveguide layer 51 and is transmitted through the first optical element 510 is diffracted by the second optical element 521 of the 2 nd waveguide layer 52 to be diffracted and enters the 2 nd waveguide layer 52, and diffracted light formed by the incident light being reflected by the first optical element 520, diffracted by the second optical element 521, and diffracted by the first optical element 520 in this order propagates in the 2 nd waveguide layer 52 as total reflection.

As shown in fig. 10, ray 1 is the incident image ray, with 100% energy; ray 2 is 0 th order light, 70% of the energy of ray 1 at the second optical element 511 of the 1 st waveguiding layer 51; ray 4 is 0 th order light, 49% of energy, of ray 2 at the first optical element 510 of the 1 st waveguiding layer 51; ray 2' is the diffracted light of ray 1 at the 1 st waveguiding layer 51, second optical element 511, at an energy of 30%; ray 3 'is the diffracted light of ray 2' at the 1 st waveguiding layer 51, first optical element 510, energy 9%; ray 4 'is 0 th order light, 21% of the energy, of ray 2' at the first optical element 510 of the 1 st waveguiding layer 51; ray 5 'is the diffracted light of ray 4' at 1 st waveguiding layer 51, second optical element 511, energy 6.3%; ray 6 'is 0 th order light, 14.7% of the energy, of ray 4' at the second optical element 511 of the 1 st waveguiding layer 51; ray 7 'is 0 th order light of ray 5' at the 1 st waveguiding layer 51 first optical element 510, 4.41% of energy; the light 8 'is diffracted light of the light 5' in the first optical element 510 of the 1 st waveguide layer 51, and has energy of 1.89%, and the light 6 'and the light 8' propagate through the 1 st waveguide layer 51 by total reflection.

In the 2 nd waveguiding layer 52, the light ray 22 is 0-order light of the light ray 4 at the second optical element 521 of the 2 nd waveguiding layer 52, with energy 34.3%; ray 24 is the 0 th order light, 24.01% of the energy of ray 22 at first optical element 520 of 2 nd waveguide layer 52; ray 22' is the diffracted light of ray 4 at the 2 nd waveguiding layer 52 at the second optical element 521, with an energy of 14.7%; ray 23 'is the light diffracted by ray 22' at the 2 nd waveguide layer 52 from the first optical element 520 at an energy of 4.41%; ray 24 'is 0 th order light, 10.29% of the energy of ray 22' at first optical element 520 of 2 nd waveguide layer 52; ray 25 'is the diffracted light of ray 24' at second optical element 521 of 2 nd waveguiding layer 52, with an energy of 3.087%; ray 26 'is the 0 th order light, 7.203% of the energy of ray 24' at second optical element 521 of 2 nd waveguiding layer 52; ray 27 'is the 0 th order light, 2.1609% of the energy of first optical element 520 at 2 nd waveguide layer 52 for ray 25'; ray 28 'is the light diffracted by ray 25' at first optical element 520 of 2 nd waveguide layer 52 with energy 0.9261%, and rays 26 ', 28' propagate by total reflection within 2 nd waveguide layer 52.

Referring to fig. 11, fig. 11 is a schematic diagram of a second optical path of the display device of the present embodiment, and the optical path in the 1 st waveguide layer 51 is the same as the optical path in the 1 st waveguide layer 51 shown in fig. 10. The optical path within the 2 nd waveguide layer 52 is: the light which is not entered into the 1 st waveguide layer 51 and transmitted from the first optical element 510 when the image light passes through the second optical element 511 of the 1 st waveguide layer 51 is incident on the 2 nd waveguide layer 52, and the light which is not entered into the 2 nd waveguide layer 52 when the image light passes through the second optical element 521 is diffracted at the first optical element 520 and diffracted light is propagated in total reflection into the 2 nd waveguide layer 52.

As shown in fig. 11, within the 2 nd waveguiding layer 52, ray 23 is the diffracted light of ray 22 at the 2 nd waveguiding layer 52 from the first optical element 520, with an energy of 10.29%; ray 25 is the diffracted light of ray 23 at the 2 nd waveguiding layer 52 from the second optical element 521, with an energy of 3.087%; ray 26 is the diffracted light of ray 25 at waveguide 2, 52 from first optical element 520 at 0.9261%; ray 27 is the 0 th order light, 2.1609% of the energy of ray 25 at the 2 nd waveguiding layer 52 for the first optical element 520; ray 28 is the 0 th order light, 7.203% of the energy of ray 23 at the second optical element 521 of the 2 nd waveguiding layer 52; ray 29 is the diffracted light of ray 26 at the 2 nd waveguiding layer 52 from the second optical element 521, energy 0.27783%; ray 210 is the diffracted light of ray 28 at waveguide 2 layer 52 from first optical element 520 at 2.1609%; light ray 211 is the 0 th order light, 0.64827% of the energy of light ray 26 at the 2 nd waveguiding layer 52 for the second optical element 521; light ray 212 is the 0 th order light, 5.0421% of the energy of the first optical element 520 of light ray 28 at the 2 nd waveguide layer 52; ray 213 is the diffracted light of ray 29 at the 2 nd waveguiding layer 52 from the first optical element 520 at an energy of 0.083349%; ray 214 is the 0 th order light, 0.194481% of the energy of ray 29 at the 2 nd waveguiding layer 52 for the first optical element 520. The light rays 211, 212, 213 propagate within the 2 nd waveguide layer 52 with total reflection.

Referring to fig. 12, fig. 12 is a schematic diagram of a third optical path of the display device of the present embodiment, and the optical path in the 1 st waveguide layer 51 is the same as the optical path in the 1 st waveguide layer 51 shown in fig. 10. The optical path within the 2 nd waveguide layer 52 is: ray 32' is the diffracted light of ray 3 at the 2 nd waveguiding layer 52 at the second optical element 521, with an energy of 2.7%; ray 33 'is the light diffracted by ray 32' at waveguide layer 2 52 from first optical element 520 at an energy of 0.81%; ray 34 'is the 0 th order light, 1.89% of the energy of ray 32' at the first optical element 520 of the 2 nd waveguiding layer 2. The light ray 34' propagates with total reflection within the 2 nd waveguiding layer 52.

Referring to fig. 13, fig. 13 is a schematic diagram of a fourth optical path of the display device of the present embodiment, and the optical path in the 1 st waveguide layer 51 is the same as the optical path in the 1 st waveguide layer 51 shown in fig. 10. The optical path within the 2 nd waveguide layer 52 is: ray 32 is 0 th order light, 6.3% of the energy, of ray 3' at the second optical element 521 of the 2 nd waveguiding layer 52; ray 33 is the diffracted light of ray 32 at waveguide 2 52 from first optical element 520 at an energy of 1.89%; ray 34 is 0 th order light, 4.41% of the energy of ray 32 at the first optical element 520 of the 2 nd waveguide layer 52; ray 35 is the diffracted light of ray 33 at the 2 nd waveguiding layer 52 from the second optical element 521 at an energy of 0.567%; ray 36 is the diffracted light of ray 35 at waveguide 2 52 from first optical element 520 at 0.1701%; ray 37 is the 0 th order light, 0.3969% of the energy of first optical element 520 at ray 35 at 2 nd waveguide layer 52; ray 38 is 0 order light, 1.323% of the energy of ray 33 at the second optical element 521 of the 2 nd waveguiding layer 52. The light rays 36, 38 propagate within the 2 nd waveguide layer with total reflection.

Referring to fig. 14, fig. 14 is a schematic diagram of a fifth optical path of the display device of the present embodiment, and the optical path in the 1 st waveguide layer 51 is the same as the optical path in the 1 st waveguide layer 51 shown in fig. 9. The optical path within the 2 nd waveguide layer 52 is: ray 42 'is the diffracted light of ray 7' at the second optical element 521 of the 2 nd waveguiding layer 52 with an energy of 0.567%. The light ray 42' propagates in the 2 nd waveguide layer by total reflection.

Referring to fig. 15, fig. 15 is a schematic diagram of a sixth optical path of the display device of the present embodiment, and the optical path in the 1 st waveguide layer 51 is the same as the optical path in the 1 st waveguide layer 51 shown in fig. 10. The optical path within the 2 nd waveguide layer 52 is: ray 42 is 0 th order light, 1.323% of the energy of ray 7' at the second optical element 521 of the 2 nd waveguiding layer 52; ray 43 is the diffracted light of ray 42 at

waveguide

2, 52 from first optical element 520 at 0.3969%; light ray 44 is the 0 th order light, 0.9261%, of light ray 32 at the 2 nd waveguiding layer 52 for the first optical element 520. The light ray 43 propagates by total reflection within the 2 nd waveguide layer 52.

Referring to fig. 16, fig. 16 is a schematic diagram of a seventh optical path of the display device of the present embodiment, where the optical path in the 1 st waveguide layer 51 is: when image light propagating from the image projection device or the preceding waveguide layer passes through the second optical element 511 of the 1 st waveguide layer 51, light not entering the 1 st waveguide layer 51 is diffracted by the first optical element 510 and diffracted light enters the 1 st waveguide layer 51 and propagates by total reflection. The optical path within the 2 nd waveguide layer 52 is: the image light propagating through the image projector or the preceding waveguide layer is diffracted by the second optical element 511 of the 1 st waveguide layer 51 to be diffracted into the 1 st waveguide layer 51, the entering light is diffracted by the first optical element 510 to be diffracted and exit to the 2 nd waveguide layer 52, and the exiting light is diffracted by the second optical element 521 of the 2 nd waveguide layer 52 to be diffracted and propagate into the 2 nd waveguide layer 52 as total reflection.

As shown in fig. 16, the optical path within 1 st waveguide layer 51 is: ray 2 is 0 th order light, 70% of the energy of ray 1 at the second optical element 511 of the 1 st waveguiding layer 51; ray 3 is the diffracted light of incident ray 2 at the 1 st waveguiding layer 51 and the first optical element 510, with an energy of 21%; ray 4 is 0 order light of ray 2 at the first optical element 510 of the 1 st waveguiding layer 51 with an energy of 49%; ray 5 is the diffracted light of ray 3 at the 1 st waveguiding layer 51, second optical element 511, with an energy of 6.3%; ray 6 is the diffracted light of ray 5 at the 1 st waveguiding layer 51 and the first optical element 510, and has an energy of 1.89%; ray 7 is 0 th order light of ray 5 at the 1 st waveguiding layer 51 first optical element 510, 4.41% of energy; light 8 is 0 th order light, 14.7% of the energy, of light 3 at the second optical element 511 of the 1 st waveguiding layer 51; ray 9 is the diffracted light of ray 6 at 1 st waveguiding layer 51, second optical element 511, with an energy of 0.567%; ray 10 is the diffracted light of ray 8 at 1 st waveguiding layer 51, first optical element 510, with an energy of 4.41%; light 11 is 0 th order light, 1.323% in energy, of light 6 at the second optical element 511 of the 1 st waveguiding layer 51; ray 12 is 0 th order light, 10.29% of the energy, of ray 8 at the first optical element 510 of the 1 st waveguiding layer 51; ray 13 is the light diffracted by ray 9 at the 1 st waveguiding layer 51 and the first optical element 510, with an energy of 0.1701%; ray 14 is the 0 th order light, 0.3969% of the energy of ray 9 at the 1 st waveguiding layer 51 for the first optical element 510. The light rays 11, 12, 13 propagate within the 1 st waveguide layer 51 by total reflection.

The optical path within the 2 nd waveguide layer 52 is: ray 52' is the diffracted light of ray 7 at the second optical element 521 of the 2 nd waveguiding layer 52 with an energy of 1.323%; ray 53 'is the light diffracted by ray 52' at waveguide layer 2 52 from first optical element 520 at 0.3969%; ray 54 'is the 0 th order light, 0.9261%, of ray 52' at the first optical element 520 of the 2 nd waveguiding layer 52. The light ray 54' propagates within the 2 nd waveguide layer with total reflection.

Referring to fig. 17, fig. 17 is a schematic diagram illustrating an eighth optical path of the display device of the present embodiment, and the optical path in the 1 st waveguide layer 51 is the same as the optical path in the 1 st waveguide layer 51 shown in fig. 16. The optical path within the 2 nd waveguide layer 52 is: ray 52 is 0 th order light of ray 7 at second optical element 521 of 2 nd waveguiding layer 52, with an energy of 3.087%; ray 53 is the light diffracted by ray 52 at waveguide layer 2 52 from first optical element 520 at 0.9261%; ray 54 is the 0 th order light, 2.1609% of the energy of ray 52 at waveguide layer 2 at first optical element 520; ray 55 is the diffracted light of ray 53 at the 2 nd waveguiding layer 52 from the second optical element 521 at an energy of 0.27783%; ray 56 is the diffracted light of ray 55 at waveguide 2 52 from first optical element 520 at 0.083349%; ray 57 is the 0 th order light, 0.194481% of the energy of first optical element 520 at 2 nd waveguide layer 52 for ray 55; ray 58 is the 0 th order light, 0.64827% of the energy of ray 53 at the second optical element 521 of the 2 nd waveguiding layer 52. The light rays 56, 58 propagate within the 2 nd waveguide layer with total reflection.

Referring to fig. 18, fig. 18 is a schematic diagram of a ninth optical path of the display device of the present embodiment, and the optical path in the 1 st waveguide layer 51 is the same as the optical path in the 1 st waveguide layer 51 shown in fig. 16. The optical path within the 2 nd waveguide layer 52 is: ray 62' is the diffracted light of ray 10 at the 2 nd waveguiding layer 52 from the second optical element 521 at an energy of 1.323%; ray 63 'is the light diffracted by ray 62' at waveguide layer 2 52 from first optical element 520 at 0.3969%; ray 64 'is the 0 th order light, 0.9261%, of ray 62' at the first optical element 520 of the 2 nd waveguiding layer 52. Light ray 64' propagates by total reflection within the 2 nd waveguide layer 52.

Referring to fig. 19, fig. 19 is a schematic diagram illustrating a tenth optical path of the display device of the present embodiment, and the optical path in the 1 st waveguide layer 51 is the same as the optical path in the 1 st waveguide layer 51 shown in fig. 16. The optical path within the 2 nd waveguide layer 52 is: ray 62 is 0 th order light, 3.087% of the energy of ray 10 at second optical element 521 of 2 nd waveguiding layer 52; ray 63 is the light diffracted by ray 62 at waveguide 2 52 from first optical element 520 at 0.9261%; ray 64 is the 0 th order light, 2.1609% of the energy of ray 62 at first optical element 520 of 2 nd waveguiding layer 52. The light ray 63 propagates by total reflection in the 2 nd waveguide layer.

As can be seen from fig. 10 to 19, the final output light of the display device of this embodiment is 6 ', 8', 26 ', 28', 211, 212, 213, 34 ', 36, 38, 42', 43, 11, 12, 13, 54 ', 56, 58, 64', and 63, the total energy of the final output light is approximately 51%, the coupling efficiency of the waveguide is 51%, that is, 51% of the energy of the light is coupled into the waveguide layer for transmission, and compared with the existing waveguide-based display device, the waveguide efficiency is improved by 143%, and the light energy utilization rate is greatly improved.

In the display device of the above specific implementation manner, the second optical element of each waveguide layer adopts a transmissive optical element based on the diffraction principle, the first optical element of each waveguide layer adopts a reflective optical element based on the diffraction principle, optionally, the second optical element of each waveguide layer also can adopt a reflective optical element based on the diffraction principle, the first optical element of each waveguide layer adopts a transmissive optical element based on the diffraction principle, please refer to fig. 20 and 21, fig. 20 is a schematic diagram of an optical path of the first optical element of the waveguide layer adopting a reflective optical element based on the diffraction principle, fig. 21 is a schematic diagram of an optical path of the second optical element of the waveguide layer adopting a transmissive optical element based on the diffraction principle, in this implementation manner, a propagation optical path of image light coupled into the waveguide layer through the first optical element and the second optical element is according to the first optical element, The optical path of the second optical element is implemented accordingly.

In this embodiment, referring to fig. 9, the first optical element 410 of each waveguide layer may be a reflective optical element based on the diffraction principle, or the first optical element 410 of each waveguide layer may be a transmissive optical element based on the diffraction principle. Alternatively, the first optical elements 410 of several of the 1 st to nth waveguide layers 41 are reflective optical elements based on the diffraction principle, and the first optical elements 410 of the other waveguide layers are transmissive optical elements based on the diffraction principle.

The second optical element 411 of each waveguide layer may be a reflective optical element based on the diffraction principle or the second optical element 411 of each waveguide layer may be a transmissive optical element based on the diffraction principle. Alternatively, the second optical elements 411 of some of the 1 st to nth waveguide layers 41 are reflective optical elements based on the diffraction principle, and the second optical elements 411 of the other waveguide layers are transmissive optical elements based on the diffraction principle.

Referring to fig. 9, the second predetermined region of each waveguide layer 41 is provided with an out-coupling portion 412 for coupling the image light propagating in the waveguide layer 41 to the viewing side of the user outside the waveguide layer 41, the image light coupled into the waveguide layer 41 propagates in the waveguide layer in a total reflection manner, the image light propagates in the turning region of the waveguide layer in a total reflection manner, and is coupled out by the out-coupling portion 412 when propagating to the second predetermined region, and the image light coupled out by each waveguide layer 41 enters the eye of the user to realize display. Wherein the outcoupling portion 412 may be an optical element based on the diffraction principle. In this embodiment, referring to fig. 9, the optical element 412 of the coupling-out section may be disposed on a side of the waveguide layer 41 away from the user viewing side. Or in other embodiments the optical elements of the outcoupling portion may be arranged at the side of the waveguide layer closer to the viewing side of the user.

Further, referring to fig. 9, an optical layer 413 that absorbs image light and allows light of other wavelength bands except for the image light to transmit is disposed on a side of the second predetermined region of each waveguide layer 41 away from the user. For the specific implementation of the optical layer 413, reference may be made to the description of embodiment 1, which is not repeated in this embodiment.

Preferably, the projections of the second predetermined regions of the waveguide layers 41 along the arrangement direction of the waveguide layers 41 do not overlap each other, or the projections of the second predetermined regions of the waveguide layers 41 along the arrangement direction of the waveguide layers partially overlap, so as to avoid the second predetermined regions of the waveguide layers from completely overlapping, and if the second predetermined regions of the two waveguide layers completely overlap, the light coupled out by the next waveguide layer is incident on the coupling-out optical element in the second predetermined region of the previous waveguide layer and is re-coupled into the waveguide layer, so that the light is coupled out as much as possible by the above arrangement, and the light enters the eyes of the user, thereby improving the waveguide efficiency and the light energy utilization ratio.

A waveguide-based display device according to the present invention is described in detail above. The principles and embodiments of the present invention are explained herein using specific examples, which are presented only to assist in understanding the method and its core concepts. It should be noted that, for those skilled in the art, it is possible to make various improvements and modifications to the present invention without departing from the principle of the present invention, and those improvements and modifications also fall within the scope of the claims of the present invention.

Claims

1. A waveguide-based display device comprising image projection means for projecting image light and a waveguide layer;

2. A waveguide-based display device as claimed in claim 1, wherein the optical layer has a coverage area coinciding with the second predetermined region of the waveguide layer.

3. A waveguide-based display device according to claim 1, wherein the image projection device produces image light with a band width of 0.1nm to 10nm, the optical layer has an absorption band width of 0.1nm to 10nm, and the optical layer has an absorption band range that coincides with the band range of the image projection device producing image light.

4. The waveguide-based display device of claim 1, wherein the optical layer is a narrow band notch filter, and the light source of the image projector is a narrow band projection light source;

5. A waveguide-based display device according to claim 1, wherein the optical layer and the waveguide layer have an air space therebetween.

6. A waveguide-based display device according to claim 5, wherein the air gap between the optical layer and the waveguide layer is in the range 0.001mm to 1 mm.

7. A waveguide based display device as claimed in claim 1, wherein the optical layer overlies a substrate.

8. The waveguide-based display device of claim 1, comprising 1 st to nth waveguide layers, wherein the 1 st to nth waveguide layers are sequentially arranged from near to far away from the image projection device, and N is a positive integer greater than or equal to 2;

9. A waveguide based display device as claimed in any one of claims 1 to 8, wherein the incoupling portion comprises optical elements arranged to one side of the first predetermined region of the waveguide layer for coupling image light into the waveguide layer;

10. A waveguide based display device as claimed in claim 8, wherein the incoupling section comprises a first optical element arranged on a side of the first predetermined region of the waveguide layer remote from the imaging means and a second optical element arranged on a side of the first predetermined region of the waveguide layer adjacent the imaging means;

11. A waveguide based display device as claimed in claim 10, wherein the first optical element of each said waveguide layer is a reflective optical element based on the principle of diffraction, or the first optical element of each said waveguide layer is a transmissive optical element based on the principle of diffraction; or the first optical elements of a plurality of waveguide layers from the 1 st to the Nth waveguide layers are reflection type optical elements based on the diffraction principle, and the first optical elements of other waveguide layers are transmission type optical elements based on the diffraction principle;

12. A waveguide-based display device as claimed in claim 1, wherein the projections of the second predetermined regions of the respective waveguide layers in the direction of the arrangement of the waveguide layers do not overlap each other or the projections of the second predetermined regions of the respective waveguide layers in the direction of the arrangement of the waveguide layers partially overlap.