A waveguide-based display device

Abstract

The present invention discloses a display device based on a waveguide, wherein an image projection device is used to project image light; a coupling portion for coupling image light into the waveguide layer is provided in a first preset area of ​​the waveguide layer, and a coupling portion for coupling image light propagating in the waveguide layer out to a user viewing side outside the waveguide layer is provided in a second preset area of ​​the waveguide layer; an optical layer that has an absorption effect on image light and allows light of other wavelengths except the image light to pass through is provided in the second preset area of ​​the waveguide layer away from the user viewing side. The optical layer allows image light leaking from the second preset area of ​​the waveguide layer to the side away from the user viewing to be absorbed by the optical layer, thereby preventing this part of the image light from leaking outside the display device, while the optical layer does not affect the passage of light of other wavelengths except the image light. Therefore, compared with the prior art, the display device of the present invention can prevent light from leaking to other directions outside the device, which helps to avoid display leakage.

Description

Technical Field

[0001] The present invention relates to the field of virtual reality display technology, and in particular to a waveguide-based display device. Background Art

[0002] Augmented reality (AR) display combines the virtual images obtained by simulation with the real scene and displays them to the user, so that the user can receive virtual image information and real image information at the same time, thus achieving an augmented reality sensory experience. Augmented reality display has been widely used in entertainment, education, industry, military, medical, tourism and other industries.

[0003] Traditional augmented reality display systems use a transmissive optical display method. In order to realize an optical transmissive augmented reality display solution, a traditional geometric optical system based on a semi-transparent and semi-reflective mirror or a free-form surface element is designed, and refraction and reflection are used to realize the superposition of virtual images and real scenes. However, this type of display system composed of traditional optical elements is limited by the total optical distance and cannot be thin and light enough, which is far from everyday glasses. In addition, due to the constraints of the Lagrange invariant, the exit pupil size of the traditional optical display system is limited, and it is usually not suitable for users with pupil distances at both ends. Compared with the traditional augmented reality display system, the waveguide-based augmented reality display solution effectively solves the above two problems. After a monochrome or color image is projected into the waveguide, the light is transmitted by total reflection in the waveguide element, which effectively reduces the thickness of the optical element. At the same time, one or more optical elements on the waveguide are used to control the step-by-step output of the image, which can achieve exit pupil expansion.

[0004] In the existing technology, waveguide-based augmented reality display solutions use diffraction optical devices, such as surface relief optical waveguides, holographic optical waveguides, etc., and can also use geometric optical devices such as array optical waveguides, etc. It mainly uses diffraction gratings to realize the incidence, deflection and emission of light, and realizes light transmission based on the principle of total reflection. It can achieve compact structure and lightweight devices, and is currently the most competitive core optical device for AR display devices.

[0005] However, in this type of augmented reality display system, after the light propagating in the waveguide element is diffracted in the exit grating area, part of it is emitted into the human eye, and the other part continues to propagate through total reflection. In the exit grating area, high-order diffraction will cause a small amount of light to leak, allowing the displayed image to be seen by the outside world, which will cause user privacy leakage. Summary of the invention

[0006] The object of the present invention is to provide a waveguide-based display device, which can prevent light from leaking to other directions outside the device compared with the prior art, and help avoid display leakage.

[0007] To achieve the above object, the present invention provides the following technical solutions:

[0008] A waveguide-based display device comprises an image projection device and a waveguide layer, wherein the image projection device is used to project image light;

[0009] A coupling portion for coupling image light into the waveguide layer is provided in a first preset area of ​​the waveguide layer, and a coupling portion for coupling image light propagating in the waveguide layer out to a user viewing side outside the waveguide layer is provided in a second preset area of ​​the waveguide layer;

[0010] An optical layer that absorbs image light and allows light of other wavelengths except the image light to pass through is arranged on the second preset area of ​​the waveguide layer away from the viewing side of the user.

[0011] Preferably, the coverage area of ​​the optical layer is consistent with the second preset area of ​​the waveguide layer.

[0012] Preferably, the wavelength band width of the image light generated by the projection device is 0.1nm-10nm, the absorption wavelength band width of the optical layer is 0.1nm-10nm, and the absorption wavelength band range of the optical layer is consistent with the wavelength band range of the image light generated by the projection device.

[0013] Preferably, the optical layer is a narrow-band notch filter, and the light source of the projection device is a narrow-band projection light source;

[0014] Alternatively, the projection device comprises a light emitting device that emits three primary color lasers respectively, and the central wavelength of the absorption band of the optical layer is consistent with the wavelength of the laser emitted by the light emitting device;

[0015] Alternatively, the projection device includes a light emitting device for generating light and a filter element for filtering the light emitted by the light emitting device, and the wavelength range of the light allowed to pass by the filter element is consistent with the absorption band range of the optical layer.

[0016] Preferably, there is an air gap between the optical layer and the waveguide layer.

[0017] Preferably, the air gap between the optical layer and the waveguide layer is 0.001 mm to 1 mm.

[0018] Preferably, the optical layer covers the substrate.

[0019] Preferably, it comprises 1st to Nth waveguide layers, the 1st to Nth waveguide layers are arranged in order from near to far from the projection device, and N is a positive integer greater than or equal to 2;

[0020] A coupling portion for coupling image light into the waveguide layer is disposed in the first preset region of each waveguide layer, a coupling portion for coupling image light propagating in the waveguide layer out to a user viewing side outside the waveguide layer is disposed in the second preset region of each waveguide layer, and an optical layer that absorbs image light and allows light of other wavelengths except image light to pass through is disposed in the second preset region of each waveguide layer away from the user viewing side;

[0021] The coupling portion of the first waveguide layer is specifically used to couple the image light projected by the projection device into the first waveguide layer, and the coupling portion of the i-th waveguide layer is specifically used to couple the image light that is not coupled into the previous waveguide layer and is transmitted from the first preset area of ​​the previous waveguide layer into the i-th waveguide layer, i∈[2,N].

[0022] Preferably, the coupling-in portion comprises an optical element disposed on one side of the first preset area of ​​the waveguide layer and coupling the image light into the waveguide layer;

[0023] The coupling-out portion comprises an optical element disposed on one side of the second preset area of ​​the waveguide layer and coupling the image light out of the waveguide layer and close to the viewing side of the user.

[0024] Preferably, the coupling-in portion comprises a first optical element arranged at a side of the first preset region of the waveguide layer away from the projection device and a second optical element arranged at a side of the first preset region of the waveguide layer close to the projection device;

[0025] The image light transmitted from the projection device or the previous waveguide layer is diffracted by the second optical element of the current waveguide layer, and the diffracted light enters the current waveguide layer. 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, and the diffracted light formed by the diffraction is transmitted in the current waveguide layer in the form of total reflection;

[0026] or / and, the image light transmitted from the projection device or the previous waveguide layer, which does not enter the current waveguide layer when passing through the second optical element, is diffracted by the first optical element and the diffracted light enters the current waveguide layer and is transmitted in the form of total reflection;

[0027] or / and, the image light propagated from the image projection device or the previous waveguide layer is diffracted by the second optical element of the current waveguide layer, and the diffracted light enters the current waveguide layer, the entered light is diffracted by the first optical element, and the diffracted light is emitted to the next waveguide layer, the emitted light is diffracted by the second optical element of the next waveguide layer, and the diffracted light enters the next waveguide layer and propagates in the form of total reflection; or / and, the light in the emitted light that passes through the second optical element of the next waveguide layer but does not enter the next waveguide layer is diffracted by the first optical element, the second optical element, and the first optical element in sequence, and the diffracted light formed is propagated in the next waveguide layer in the form of total reflection;

[0028] or / and, the image light transmitted from the projection device or the previous waveguide layer is diffracted by the second optical element of the current waveguide layer, and the diffracted light enters the current waveguide layer, the entering light is reflected by the first optical element in sequence, and diffracted by the second optical element, and 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 and propagates in the form of total reflection; or / and, the light in the emitted light that passes through the second optical element of the next waveguide layer but does not enter the next waveguide layer is diffracted by the first optical element, and the diffracted light enters the next waveguide layer and propagates in the form of total reflection;

[0029] or / and, among the image light rays propagated from the projection device or the previous waveguide layer, the light rays that do not enter the current waveguide layer when passing through the second optical element of the current waveguide layer are sequentially diffracted by the first optical element and the second optical element, and the diffracted light is emitted to the next waveguide layer through the first optical element, and the emitted light rays are diffracted by the second optical element of the next waveguide layer, and the diffracted light enters the next waveguide layer and propagates in the form of total reflection; or / and, among the emitted light rays that do not enter the next waveguide layer when passing through the second optical element of the next waveguide layer are sequentially diffracted by the first optical element, the second optical element, and the first optical element, and the diffracted light formed is propagated in the next waveguide layer in the form of total reflection;

[0030] or / and, among the image light rays propagated from the projection device or the previous waveguide layer, the light rays that do not enter the current waveguide layer when passing through the second optical element of the current waveguide layer are diffracted by the first optical element, reflected by the second optical element, and diffracted by the first optical element in sequence, and the diffracted light is emitted to the next waveguide layer, and the emitted light rays are diffracted by the second optical element of the next waveguide layer, and the diffracted light enters the next waveguide layer and propagates in the form of total reflection; or / and, among the emitted light rays that do not enter the next waveguide layer when passing through the second optical element of the next waveguide layer are diffracted by the first optical element, and the diffracted light enters the next waveguide layer and propagates in the form of total reflection.

[0031] Preferably, the first optical element of each waveguide layer is a reflective optical element based on the diffraction principle, or the first optical element of each waveguide layer is a transmissive optical element based on the diffraction principle; or the first optical elements of some waveguide layers from the 1st to the Nth waveguide layers are reflective optical elements based on the diffraction principle, and the first optical elements of other waveguide layers are transmissive optical elements based on the diffraction principle;

[0032] 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 some waveguide layers from the 1st to the 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.

[0033] Preferably, the projections of the second preset regions of the waveguide layers along the arrangement direction of the waveguide layers do not overlap with each other, or the projections of the second preset regions of the waveguide layers along the arrangement direction of the waveguide layers partially overlap with each other.

[0034] As can be seen from the above technical solution, a waveguide-based display device provided by the present invention includes an image projection device and a waveguide layer, wherein the image projection device is used to project image light, and a coupling portion for coupling the image light into the waveguide layer is arranged in the first preset area of ​​the waveguide layer, and a coupling portion for coupling the image light propagating in the waveguide layer out to the user viewing side outside the waveguide layer is arranged in the second preset area of ​​the waveguide layer, and the image light coupled out by the waveguide layer enters the user's eyes, thereby realizing the display of a virtual image. An optical layer that has an absorption effect on the image light and allows light of other wavelengths other than the image light to pass through is arranged in the second preset area of ​​the waveguide layer away from the user viewing side, so that the image light leaking from the second preset area of ​​the waveguide layer to the side away from the user viewing side will be absorbed by the optical layer, thereby preventing this part of the image light from leaking out of the display device, and the optical layer does not affect the passage of light of other wavelengths other than the image light, thereby preventing the light from leaking out of the display device while not affecting the external light from being transmitted to the user's eyes for imaging. Therefore, compared with the prior art, the display device of the present invention can prevent light from leaking to other directions outside the device, which helps to avoid display leakage and effectively protect user privacy. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0036] Figure 1 A schematic diagram of leakage light generated by a conventional display device using a waveguide;

[0037] Figure 2 is a schematic diagram of a waveguide-based display device according to a first embodiment of the present invention;

[0038] Figure 3 for Figure 2 A schematic diagram of the optical path of the display device shown;

[0039] Figure 4 is a schematic diagram of a light path in which no optical layer is provided in the second preset area of ​​the waveguide layer;

[0040] Figure 5 is a transmission spectrum diagram of an optical layer in a specific embodiment;

[0041] Figure 6 is a schematic diagram of a waveguide-based display device according to a second embodiment of the present invention;

[0042] Figure 7 A schematic diagram of an optical path of an existing waveguide-based display device;

[0043] Figure 8 A schematic diagram of an optical path of a display device including two waveguide layers according to a second embodiment of the present invention;

[0044] Fig. 9 is a schematic diagram of a waveguide-based display device according to a third embodiment of the present invention;

[0045] Figure 10-Figure 19 The following are schematic diagrams of ten optical paths existing in the display device of the third embodiment of the present invention;

[0046] Fig. 20 A schematic diagram of an optical path in which the first optical element of the waveguide layer in the display device according to the third embodiment of the present invention is a reflective optical element based on the diffraction principle;

[0047] Fig.21 This is a schematic diagram of the optical path of a second optical element of a waveguide layer in a display device according to a third embodiment of the present invention, which is a transmissive optical element based on the diffraction principle. DETAILED DESCRIPTION

[0048] In order to enable those skilled in the art to better understand the technical solutions in the present invention, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work should fall within the scope of protection of the present invention.

[0049] Please refer to Figure 1 , Figure 1 This is a schematic diagram of leakage light generated by an existing display device using a waveguide. When a user wears the display device, the leakage light generated by the display device will be emitted in a direction away from the user's eyes. This part of the image light will propagate in other directions outside the device, so that the image can be seen from the outside, causing display leakage.

[0050] In view of this, an embodiment of the present invention provides a waveguide-based display device, comprising an image projection device and a waveguide layer, wherein the image projection device is used to project image light;

[0051] A coupling portion for coupling image light into the waveguide layer is provided in a first preset area of ​​the waveguide layer, and a coupling portion for coupling image light propagating in the waveguide layer out to a user viewing side outside the waveguide layer is provided in a second preset area of ​​the waveguide layer;

[0052] An optical layer that absorbs image light and allows light of other wavelengths except the image light to pass through is arranged on the second preset area of ​​the waveguide layer away from the viewing side of the user.

[0053] The waveguide layer is a waveguide structure that can guide the propagation of light. The projection device projects image light onto the waveguide layer, and the coupling portion of the waveguide layer couples the image light projected by the projection device into the waveguide layer. The coupling portion arranged in the second preset area of ​​the waveguide layer couples the image light propagating in the waveguide layer out to the user viewing side outside the waveguide layer, and the image light coupled out by the waveguide layer enters the user's eyes, thereby realizing the display of a virtual image. Among them, an optical layer that has an absorption effect on the image light and allows other bands of light except the image light to pass through is arranged on the second preset area of ​​the waveguide layer away from the user viewing side, so that the image light leaking from the second preset area of ​​the waveguide layer to the side away from the user viewing side will be absorbed by the optical layer, thereby preventing this part of the image light from leaking out of the display device, and the optical layer does not affect the passage of other bands of light except the image light, thereby preventing the light from leaking out of the display device and not affecting the external light from being transmitted to the user's eyes for imaging. Therefore, compared with the prior art, the display device of the present invention can prevent the light from leaking to other directions outside the device, which helps to avoid display leakage and effectively protects user privacy and information security.

[0054] The following is a detailed description of the waveguide-based display device in conjunction with the accompanying drawings and specific embodiments. Figure 2 , Figure 2 Schematic diagram of a waveguide-based display device of the first embodiment. As can be seen from the figure, the display device includes an image projection device 10 and a waveguide layer 11. The image projection device 10 is used to project image light. The image projection device 10 can be a projection light machine, and can be various types of projection light machines, all of which are within the protection scope of the present invention.

[0055] A coupling-in portion for coupling image light into the waveguide layer 11 is provided in the first preset region of the waveguide layer 11, and a coupling-out portion for coupling image light propagating in the waveguide layer 11 out to the user viewing side outside the waveguide layer 11 is provided in the second preset region of the waveguide layer 11. The image light generated by the projection device 10 is coupled into the waveguide layer 11 through the coupling-in portion, and the coupled-in image light propagates in the waveguide layer 11 in the form of total reflection. The image light propagates in the turning region of the waveguide layer 11 in the form of total reflection, and is coupled out by the coupling-out portion when propagating to the second preset region. The coupled-out image light enters the user's eyes to realize virtual image display.

[0056] Optionally, the coupling part may be an optical element based on the diffraction principle. For details, please refer to Figure 2 and Figure 3 , Figure 3 for Figure 2 The optical path schematic diagram of the display device shown in the figure, the coupling part includes an optical element 110 arranged at one side of the first preset area of ​​the waveguide layer 11, which couples the image light into the waveguide layer 11, and the image light incident on the waveguide layer 11 is diffracted by the optical element 110 of the waveguide layer coupling part, and the generated diffracted light is coupled into the waveguide layer 11. Optionally, refer to Figure 2 and Figure 3 As shown, the optical element 110 of the coupling part can be arranged on the side of the waveguide layer 11 away from the projection device 10, or the optical element of the coupling part can also be arranged on the side of the waveguide layer close to the projection device.

[0057] The outcoupling part can be an optical element based on the diffraction principle. For details, please refer to Figure 2 and Figure 3 The outcoupling part includes an optical element 111 disposed on one side of the second preset area of ​​the waveguide layer 11, coupling the image light out of the waveguide layer 11 near the user viewing side, and the image light propagating in the waveguide layer 11 is diffracted by the optical element 111 of the outcoupling part of the waveguide layer 11, and the generated diffracted light is coupled out of the waveguide layer 11. Optional as Figure 2 and Figure 3 As shown, the optical element 111 of the outcoupling part can be arranged on the side of the waveguide layer 11 away from the user. Alternatively, in other embodiments, the optical element of the outcoupling part can also be arranged on the side of the waveguide layer close to the user.

[0058] Please refer to Figure 4 , Figure 4Schematic diagram of the optical path in the second preset area of ​​the waveguide layer where no optical layer is provided. It can be seen from the figure that when the light reaches the second preset area of ​​the waveguide layer 11, part of the light will be coupled to the side of the waveguide layer near the user through the outcoupling part, and part of the light will leak to the side of the waveguide layer far from the user. For the display device of this embodiment, please refer to Figure 3 , an optical layer 112 is provided on the side of the second preset area of ​​the waveguide layer 11 away from the user's viewing. The optical layer 112 has an absorption effect on the image light and allows light of other wavelengths except the image light to pass through. For the image light emitted from the second preset area of ​​the waveguide layer 11 to the side away from the user's viewing, that is, the leaked light, the optical layer 112 can absorb this part of the image light, thereby preventing this part of the image light from leaking to the side of the waveguide layer away from the user's viewing and leaking to the outside of the display device. In addition, the optical layer 112 allows light of other wavelengths except the image light to pass through, so as not to affect the external scene light from entering the user's eyes and not to affect the user's viewing of the real external scene.

[0059] Preferably, the coverage of the optical layer 112 is consistent with the second preset area of ​​the waveguide layer 11, that is, the second preset area of ​​the waveguide layer 11 is completely covered by the optical layer 112, so that the light leaking from the second preset area of ​​the waveguide layer to the side away from the user can be absorbed by the optical layer 112, thereby effectively protecting the user's privacy and greatly improving the security of user information.

[0060] Optionally, the image light generated by the projection device 10 has a wavelength band width of 0.1nm to 10nm, the absorption wavelength band width of the optical layer 112 is 0.1nm to 10nm, and the absorption wavelength band range of the optical layer 112 is consistent with the wavelength band range of the image light generated by the projection device 10, that is, the absorption peak of the optical layer 112 corresponds to the wavelength range of the light generated by the projection device. The projection device 10 is configured to use a narrow-band light source, and the corresponding optical layer 112 can use a narrow-band filtering optical layer. The absorption wavelength band of the optical layer 112 is relatively narrow, so that the optical layer will not affect the transmission of the external scene light to the user's eyes as much as possible, and will not affect the user's viewing of the real external scene.

[0061] Optionally, the optical layer 112 is a narrowband notch filter, and the light source of the projection device 10 is matched with a narrowband projection light source. The absorption peak of the optical layer 112 corresponds to the wavelength of the narrowband light source, and only absorbs the light of the corresponding light source wavelength, and transmits other wavelengths of light, which effectively prevents the light of the projected image from leaking out, protecting user privacy and information security. The optical layer 112 will also absorb the corresponding wavelength light in the external light, but the wavelength range is very narrow, only a few nanometers, and does not affect the transmission of other external light to the human eye, that is, it does not affect the user's viewing of the real scene of the outside world.

[0062] Optionally, the projection device 10 may include a light emitting device that emits three primary color lasers respectively, and the central wavelength of the absorption band of the optical layer 112 is consistent with the wavelength of the laser emitted by the light emitting device. Specifically, the projection device 10 may include a light emitting device that emits red laser, green laser, and blue laser respectively, and the optical layer includes three narrow-band notch absorption peaks, and the central wavelength of each absorption peak is consistent with the wavelength of the laser emitted by the three light emitting devices. Please refer to Figure 5 , Figure 5 The transmission spectrum of the optical layer in a specific embodiment shows that the optical layer includes three absorption bands, and the central wavelengths of each absorption band are blue light, green light and red light, respectively. Light of other bands can pass through the optical layer, and red light, green light and blue light are absorbed. The laser band generated by the light emitting device is narrow, so the projection device generates image light in a narrow band range.

[0063] Optionally, the projection device 10 may include a light emitting device for generating light and a filter element for filtering the light emitted by the light emitting device, wherein the wavelength range of the light allowed to pass by the filter element is consistent with the absorption band range of the optical layer, so that the wavelength range of the image light generated by the projection device is consistent with the absorption band range of the optical layer 112. Optionally, the light emitting device may be an LED, or may be other types of light emitting devices.

[0064] Preferably, there may be an air gap 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 propagation of light in the waveguide layer, and thus not to affect the human eye receiving the image light and viewing the image. Specifically, when an optical element for coupling the image light propagating in the waveguide layer out of the waveguide layer is provided on the side of the second preset area of ​​the waveguide layer away from the user viewing, there is an air gap between the optical layer and the outer surface of the optical element. Specifically, the air gap between the optical layer and the waveguide layer may be 0.001 mm to 1 mm.

[0065] Optionally, the optical layer 112 may be covered on the substrate, and the optical layer and the substrate are arranged together on the side of the waveguide layer 11 away from the user. The substrate may be a glass substrate or a plastic substrate, and the optical layer 112 may be a coating layer.

[0066] Please refer to Figure 6 , Figure 6 Schematic diagram of a waveguide-based display device of the second embodiment. As can be seen from the figure, the display device includes an image projection device 20 and first to Nth waveguide layers 21, where N is a positive integer greater than or equal to 2. The image projection device 20 is used to project image light. The image projection device 20 can be a projection light machine, and can be various types of projection light machines, all of which are within the protection scope of the present invention.

[0067] The first to Nth waveguide layers 21 are arranged in order from near to far from the projection device 20. A coupling portion for coupling image light into the waveguide layer 21 is provided in the first preset area of ​​each waveguide layer 21. Please refer to Figure 6 , the coupling part may specifically include an optical element 210 disposed on the side of the first preset area of ​​the waveguide layer 21 away from the projection device 20, the optical element 210 is used to couple the image light into the waveguide layer 21, the image light propagated from the projection 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 the form of total reflection. Among them, the coupling part of the first waveguide layer is used to couple the image light projected by the projection device 20 into the first waveguide layer, and the coupling part of the i-th waveguide layer is used to couple the image light that is not coupled into the previous waveguide layer and is transmitted from the first preset area of ​​the previous waveguide layer into the i-th waveguide layer, i∈[2,N].

[0068] Please refer to Figure 7 , Figure 7 The optical path diagram of the existing waveguide-based display device is shown in FIG. 6 . Assuming that the diffraction efficiency of the coupling element 61 is 30%, without considering absorption, the energy of the incident light 1 is 100%, the light 2 is the 0th-order outgoing light of the incident light 1, with an energy of 70%, the light 3 is the diffracted light of the incident light 1, with an energy of 30%; the light 4 is the diffracted light of the light 3, with an energy of 9%; the light 5 is the light coupled into the waveguide layer 60 by the coupling element 61, with an energy of 21%, that is, the light with 21% energy enters the waveguide layer 60 for transmission, and the coupling efficiency of the waveguide-based display device is 21%. The display device of this embodiment sets multiple waveguide layers, and the image light that is not coupled into the waveguide layer by the previous waveguide layer can be coupled again by the next waveguide layer, for example Figure 7 In the display device shown, the 0th-order output light 2 transmitted through the waveguide layer and the light coupled into the waveguide layer are diffracted again by the coupling element to couple out the light 4 outside the waveguide layer. The display device of this embodiment can couple this part of light again through the rear waveguide layer. Therefore, it can be seen that compared with the prior art, the display device of this embodiment can reduce light leakage, improve the utilization rate of light energy, and enhance the performance of the display device and user experience.

[0069] Please refer to Figure 8 , Figure 8The waveguide-based display device of this embodiment includes a light path schematic diagram of two waveguide layers, wherein the display device includes two waveguide layers, namely, the first waveguide layer 31 and the second waveguide layer 32. As shown in the figure, a coupling portion 310 is provided on one side of the first preset area of ​​the first waveguide layer 31, and a coupling portion 320 is provided on one side of the first preset area of ​​the second waveguide layer 32. It is assumed that the diffraction efficiency of the optical element of each coupling portion is 30%. Light 1 is the incident image light with an energy of 100%, light 2 is the 0th order outgoing light of light 1 with an energy of 70%; light 3 is the diffracted light of light 1 with an energy of 30%; light 4 is the diffracted light of light 3 with an energy of 9%; and light 5 is the 0th order light of light 3 in the coupling portion 310 with an energy of 21%. Light 6 is the diffracted light of light 2 in the coupling-in section 320 of the second waveguide layer 32, with an energy of 21%; Light 7 is the 0th order light of light 2 in the coupling-in section 320, with an energy of 49%; Light 8 is the diffracted light of light 6 in the coupling-in section 320, with an energy of 6.3%; Light 9 is the 0th order light of light 6 in the coupling-in section 320, with an energy of 14.7%; Light 10 is the diffracted light of light 4 in the coupling-in section 320, with an energy of 2.7%; Light 11 is the 0th order light of light 4 in the coupling-in section 320, with an energy of 6.3%. It can be seen that the combined coupling efficiency of the first waveguide layer 31 and the second waveguide layer 32 is 38.4%, that is, 38.4% of the energy of light is coupled into the waveguide layer for transmission. It can be seen that Figure 7 Compared with the display device shown in FIG. 1 , the waveguide efficiency of the display device in this embodiment is increased by 83%, thereby greatly improving the light energy utilization rate.

[0070] exist Figure 6 and Figure 8 In the display device shown, an example is given in which the optical element included in the coupling portion is arranged on the side of the first preset area of ​​the waveguide layer 21 away from the projection device 20. Optionally, in the display device, the optical element included in the coupling portion for coupling the image light into the waveguide layer may also be arranged on the side of the first preset area of ​​the waveguide layer close to the projection device, which is also within the protection scope of the present invention.

[0071] In this embodiment, the coupling part of each waveguide layer may adopt a reflective optical element based on the diffraction principle, or the coupling part of each waveguide layer may adopt a transmissive optical element based on the diffraction principle. Alternatively, the coupling parts of some waveguide layers from the first to the Nth waveguide layers are reflective optical elements based on the diffraction principle, and the coupling parts of other waveguide layers are transmissive optical elements based on the diffraction principle, all of which are within the protection scope of the present invention. The optical element of the coupling part may be a grating, and the grating structure of the grating of the coupling part of each waveguide layer may be the same or different.

[0072] Please refer to Figure 6In the second preset area of ​​each waveguide layer 21, a coupling-out portion 211 is provided for coupling the image light propagating in the waveguide layer 21 out to the user's viewing side outside the waveguide layer 21. The image light coupled into the waveguide layer 21 propagates in the waveguide layer in the form of total reflection. The image light propagates in the turning area of ​​the waveguide layer in the form of total reflection. When propagating to the second preset area, it is coupled out by the coupling-out portion 211. The image light coupled out by each waveguide layer 21 enters the user's eyes to realize display. The coupling-out portion 211 can be an optical element based on the diffraction principle. In this embodiment, reference Figure 6 As shown, the optical element 211 of the outcoupling part can be arranged on the side of the waveguide layer 21 away from the user. Alternatively, in other embodiments, the optical element of the outcoupling part can also be arranged on the side of the waveguide layer close to the user.

[0073] For further information, please refer to Figure 6 and Figure 8 In the second preset area of ​​each waveguide layer 21, an optical layer 212 is disposed on the side away from the user viewing, which absorbs the image light and allows light of other wavelengths except the image light to pass through. The specific implementation of the optical layer 212 can refer to the description of the previous embodiment, and will not be repeated in this embodiment.

[0074] Preferably, the projections of the second preset areas of each waveguide layer 21 along the arrangement direction of the waveguide layers 21 do not overlap with each other, or the projections of the second preset areas of each waveguide layer 21 along the arrangement direction of the waveguide layers partially overlap. The purpose of such a setting is to avoid the second preset areas of each waveguide layer from completely overlapping. If the second preset areas of two waveguide layers completely overlap, the light coupled out of the latter waveguide layer will be incident on the coupling-out optical element of the second preset area of ​​the former waveguide layer and will be re-coupled into the waveguide layer. Therefore, through the above setting, the light can be coupled out as much as possible, and as much light as possible can be coupled out and enter the user's eyes, thereby improving the waveguide efficiency and the light energy utilization rate.

[0075] Please refer to Fig. 9 , Fig. 9 Schematic diagram of a waveguide-based display device of the third embodiment. As can be seen from the figure, the display device includes an image projection device 40 and first to Nth waveguide layers 41, where N is a positive integer greater than or equal to 2. The image projection device 40 is used to project image light. The image projection device can be a projection light machine, and can be various types of projection light machines, all of which are within the protection scope of the present invention.

[0076] The 1st to Nth waveguide layers 41 are arranged in sequence from near to far from the projection device 40, and a coupling portion for coupling image light into the waveguide layer 41 is provided in the first preset area of ​​each waveguide layer 41. The coupling portion specifically includes a first optical element 410 provided in the first preset area of ​​the waveguide layer 41 on the side away from the projection device 40 and a second optical element 411 provided in the first preset area of ​​the waveguide layer 41 on the side close to the projection device 40.

[0077] Preferably, the coupling-in portion of the waveguide layer 41 can achieve: light from the image light propagated from the projection device 40 or the previous waveguide layer 41 that does not enter the current waveguide layer 41 when passing through the second optical element is diffracted by the first optical element and the diffracted light enters the current waveguide layer 41 and propagates in the form of total reflection.

[0078] Further preferably, the coupling-in part of the waveguide layer 41 can achieve: the image light propagated from the projection device 40 or the previous waveguide layer 41 is diffracted by the second optical element of the current waveguide layer and the diffracted light enters the current waveguide layer 41, and the entering light is sequentially reflected by the first optical element, diffracted by the second optical element, and diffracted by the first optical element to form the diffracted light, which propagates in the current waveguide layer 41 in the form of total reflection.

[0079] Further preferably, the coupling-in portion of the waveguide layer 41 can achieve: the image light propagated from the projection device 40 or the previous waveguide layer 41 is diffracted by the second optical element of the current waveguide layer 41 and the diffracted light enters the current waveguide layer 41, the incoming light is diffracted by the first optical element and the diffracted light is emitted to the next waveguide layer 41, the outgoing 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 propagates in the form of total reflection; or / and, the light in the outgoing light that passes through the second optical element of the next waveguide layer 41 but does not enter the next waveguide layer 41 is diffracted by the first optical element, the second optical element and the first optical element in sequence to form the diffracted light, which propagates in the next waveguide layer in the form of total reflection.

[0080] Further preferably, the coupling-in portion of the waveguide layer 41 can achieve: the image light propagated from the projection device 40 or the previous waveguide layer 41 is diffracted by the second optical element of the current waveguide layer 41, and the diffracted light enters the current waveguide layer 41; the incoming light is reflected by the first optical element and diffracted by the second optical element in sequence, and the diffracted light is emitted to the next waveguide layer 41 through the first optical element; the outgoing 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 propagates in the form of total reflection; or / and, the light in the outgoing light that passes through the second optical element of the next waveguide layer 41 but does not enter the next waveguide layer 41 is diffracted by the first optical element, and the diffracted light enters the next waveguide layer 41 and propagates in the form of total reflection.

[0081] Further preferably, the coupling-in portion of the waveguide layer 41 can achieve: the light rays among the image light rays propagated from the projection device 40 or the previous waveguide layer 41 that do not enter the current waveguide layer 41 when passing through the second optical element of the current waveguide layer 41 are sequentially diffracted by the first optical element and the second optical element, and the diffracted light is emitted to the next waveguide layer 41 through the first optical element, and the emitted light rays are diffracted by the second optical element of the next waveguide layer 41, and the diffracted light enters the next waveguide layer 41 and propagates in the form of total reflection; or / and the light rays among the emitted light rays that do not enter the next waveguide layer 41 when passing through the second optical element of the next waveguide layer 41 are sequentially diffracted by the first optical element, the second optical element, and the first optical element, and the diffracted light formed is propagated in the form of total reflection in the next waveguide layer 41.

[0082] Further preferably, the coupling-in portion of the waveguide layer 41 can achieve: the light rays among the image light rays propagated from the projection device 40 or the previous waveguide layer 41 that do not enter the current waveguide layer 41 when passing through the second optical element of the current waveguide layer 41 are sequentially diffracted by the first optical element, reflected by the second optical element, and diffracted by the first optical element, and the diffracted light rays are emitted to the subsequent waveguide layer 41, and the emitted light rays are diffracted by the second optical element of the subsequent waveguide layer 41, and the diffracted light rays enter the subsequent waveguide layer 41 and propagate in the form of total reflection; or / and the light rays among the emitted light rays that do not enter the subsequent waveguide layer 41 when passing through the second optical element of the subsequent waveguide layer 41 are diffracted by the first optical element, and the diffracted light rays enter the subsequent waveguide layer 41 and propagate in the form of total reflection.

[0083] In a specific implementation of the display device of this embodiment, any one or several of the above-mentioned propagation light paths may exist simultaneously in each waveguide layer of the display device, thereby realizing waveguide transmission of image light, thereby greatly improving the waveguide efficiency and the light energy utilization rate compared with the existing waveguide-based display device.

[0084] Exemplarily, if the second optical element of each waveguide layer of the display device of this embodiment adopts a transmissive optical element based on the diffraction principle, and the first optical element of each waveguide layer adopts a reflective optical element based on the diffraction principle, in this embodiment, there are at least ten light paths propagating simultaneously in each waveguide layer of the display device (not considering the case where the light transmission energy is low). The following describes the ten light paths that exist simultaneously in the display device of this embodiment one by one in conjunction with the optical path schematic diagram, wherein the display device includes two waveguide layers, namely the first waveguide layer 51 and the second waveguide layer 52, as an example, and the first optical element 510 is arranged on the side of the first preset area of ​​the first waveguide layer 51 away from the projection device, and the first optical element 520 is arranged on the side of the first preset area of ​​the second waveguide layer 52 away from the projection device.

[0085] Please refer to Fig.10 , Fig.10 Schematic diagram of the first optical path of the display device of this embodiment. The optical path in the first waveguide layer 51 is as follows: the image light propagated from the projection device or the previous waveguide layer is diffracted by the second optical element 511 of the first waveguide layer 51, and the diffracted light enters the first waveguide layer 51. The entering light is reflected by the first optical element 510, diffracted by the second optical element 511, and the diffracted light formed by the diffraction of the first optical element 510 is propagated in the first waveguide layer 51 in the form of total reflection. The optical path in the second waveguide layer 52 is as follows: the image light does not enter the first waveguide layer 51 when passing through the second optical element 511 of the first waveguide layer 51 and is transmitted from the first optical element 510, is diffracted by the second optical element 521 of the second waveguide layer 52, and the diffracted light enters the second waveguide layer 52. The entering light is reflected by the first optical element 520, diffracted by the second optical element 521, and the diffracted light formed by the diffraction of the first optical element 520 is propagated in the second waveguide layer 52 in the form of total reflection.

[0086] like Fig.10 As shown, light 1 is the incident image light, with an energy of 100%; light 2 is the 0th order light of light 1 in the second optical element 511 of the first waveguide layer 51, with an energy of 70%; light 4 is the 0th order light of light 2 in the first optical element 510 of the first waveguide layer 51, with an energy of 49%; light 2' is the diffracted light of light 1 in the second optical element 511 of the first waveguide layer 51, with an energy of 30%; light 3' is the diffracted light of light 2' in the first optical element 510 of the first waveguide layer 51, with an energy of 9%; light 4' is the diffracted light of light 2' in the first optical element 510 of the first waveguide layer 51 The 0th order light has an energy of 21%; the light 5' is the diffracted light of the light 4' in the second optical element 511 of the first waveguide layer 51, with an energy of 6.3%; the light 6' is the 0th order light of the light 4' in the second optical element 511 of the first waveguide layer 51, with an energy of 14.7%; the light 7' is the 0th order light of the light 5' in the first optical element 510 of the first waveguide layer 51, with an energy of 4.41%; the light 8' is the diffracted light of the light 5' in the first optical element 510 of the first waveguide layer 51, with an energy of 1.89%. The light rays 6' and 8' are propagated in the first waveguide layer 51 by total reflection.

[0087] In the second waveguide layer 52, light 22 is the 0th order light of light 4 in the second optical element 521 of the second waveguide layer 52, with an energy of 34.3%; light 24 is the 0th order light of light 22 in the first optical element 520 of the second waveguide layer 52, with an energy of 24.01%; light 22' is the diffracted light of light 4 in the second optical element 521 of the second waveguide layer 52, with an energy of 14.7%; light 23' is the diffracted light of light 22' in the first optical element 520 of the second waveguide layer 52, with an energy of 4.41%; light 24' is the 0th order light of light 22' in the first optical element 520 of the second waveguide layer 52, with an energy of 10.29%; light 25' is the diffracted light of light 24' in the second waveguide layer 52 the second optical element 521, with energy 3.087%; light 26' is the 0th order light of light 24' in the second waveguide layer 52 the second optical element 521, with energy 7.203%; light 27' is the 0th order light of light 25' in the first optical element 520 in the second waveguide layer 52, with energy 2.1609%; light 28' is the diffracted light of light 25' in the first optical element 520 in the second waveguide layer 52, with energy 0.9261%. Lights 26' and 28' propagate in the second waveguide layer 52 by total reflection.

[0088] Please refer to Fig.11 , Fig.11 is a schematic diagram of a second optical path of the display device of this embodiment, wherein the optical path in the first waveguide layer 51 is Fig.10 The optical paths in the first waveguide layer 51 are the same as shown. The optical path in the second waveguide layer 52 is as follows: the light that does not enter the first waveguide layer 51 when the image light passes through the second optical element 511 of the first waveguide layer 51 and is transmitted from the first optical element 510 enters the second waveguide layer 52, and the light that does not enter the second waveguide layer 52 when passing through the second optical element 521 is diffracted at the first optical element 520, and the diffracted light enters the second waveguide layer 52 and propagates in the form of total reflection.

[0089] like Fig.11As shown, in the second waveguide layer 52, light 23 is the diffracted light of light 22 in the first optical element 520 of the second waveguide layer 52, with an energy of 10.29%; light 25 is the diffracted light of light 23 in the second optical element 521 of the second waveguide layer 52, with an energy of 3.087%; light 26 is the diffracted light of light 25 in the first optical element 520 of the second waveguide layer 52, with an energy of 0.9261%; light 27 is the 0th order light of light 25 in the first optical element 520 of the second waveguide layer 52, with an energy of 2.1609%; light 28 is the 0th order light of light 23 in the second optical element 521 of the second waveguide layer 52, with an energy of 7.203%; light 29 is the diffracted light of light 26 in the second optical element 521 of the second waveguide layer 52 The diffracted light of the first optical element 521 of the second waveguide layer 52 has an energy of 0.27783%. The light 210 is the diffracted light of the light 28 in the first optical element 520 of the second waveguide layer 52, with an energy of 2.1609%. The light 211 is the 0th order light of the light 26 in the second optical element 521 of the second waveguide layer 52, with an energy of 0.64827%. The light 212 is the 0th order light of the light 28 in the first optical element 520 of the second waveguide layer 52, with an energy of 5.0421%. The light 213 is the diffracted light of the light 29 in the first optical element 520 of the second waveguide layer 52, with an energy of 0.083349%. The light 214 is the 0th order light of the light 29 in the first optical element 520 of the second waveguide layer 52, with an energy of 0.194481%. The light 211, 212, and 213 are propagated by total reflection in the second waveguide layer 52.

[0090] Please refer to Fig.12 , Fig.12 is a schematic diagram of a third optical path of the display device of this embodiment, wherein the optical path in the first waveguide layer 51 is Fig.10 The optical paths in the first waveguide layer 51 are the same as shown. The optical paths in the second waveguide layer 52 are as follows: light 32' is the diffracted light of light 3 in the second optical element 521 of the second waveguide layer 52, with an energy of 2.7%; light 33' is the diffracted light of light 32' in the first optical element 520 of the second waveguide layer 52, with an energy of 0.81%; light 34' is the 0th order light of light 32' in the first optical element 520 of the second waveguide layer 2, with an energy of 1.89%. Light 34' is propagated by total reflection in the second waveguide layer 52.

[0091] Please refer to Fig.13 , Fig.13 is a schematic diagram of a fourth optical path of the display device of this embodiment, wherein the optical path in the first waveguide layer 51 is Fig.10The optical paths in the first waveguide layer 51 are the same. The optical path in the second waveguide layer 52 is as follows: light 32 is the 0th order light of light 3' in the second optical element 521 of the second waveguide layer 52, with an energy of 6.3%; light 33 is the diffracted light of light 32 in the first optical element 520 of the second waveguide layer 52, with an energy of 1.89%; light 34 is the 0th order light of light 32 in the first optical element 520 of the second waveguide layer 52, with an energy of 4.41%; light 35 is the diffracted light of light 33 in the second optical element 521 of the second waveguide layer 52, with an energy of 0.567%; light 36 is the diffracted light of light 35 in the first optical element 520 of the second waveguide layer 52, with an energy of 0.1701%; light 37 is the 0th order light of light 35 in the first optical element 520 of the second waveguide layer 52, with an energy of 0.3969%; and light 38 is the 0th order light of light 33 in the second optical element 521 of the second waveguide layer 52, with an energy of 1.323%. Light rays 36 and 38 propagate by total reflection in the second waveguide layer.

[0092] Please refer to Fig.14 , Fig.14 is a fifth optical path schematic diagram of the display device of this embodiment, the optical path in the first waveguide layer 51 is Fig. 9 The optical path in the first waveguide layer 51 is the same as shown. The optical path in the second waveguide layer 52 is: the light 42' is the diffracted light of the light 7' in the second optical element 521 of the second waveguide layer 52, with an energy of 0.567%. The light 42' is propagated by total reflection in the second waveguide layer.

[0093] Please refer to Fig.15 , Fig.15 is a sixth optical path schematic diagram of the display device of this embodiment, the optical path in the first waveguide layer 51 is Fig.10 The optical paths in the first waveguide layer 51 are the same as shown. The optical paths in the second waveguide layer 52 are as follows: light 42 is the 0th order light of light 7' in the second optical element 521 of the second waveguide layer 52, with an energy of 1.323%; light 43 is the diffracted light of light 42 in the first optical element 520 of the second waveguide layer 52, with an energy of 0.3969%; light 44 is the 0th order light of light 32 in the first optical element 520 of the second waveguide layer 52, with an energy of 0.9261%. Light 43 propagates in the second waveguide layer 52 by total reflection.

[0094] Please refer to Fig.16 , Fig.16Schematic diagram of the seventh optical path of the display device of this embodiment. The optical path in the first waveguide layer 51 is: the image light propagated from the projection device or the previous waveguide layer, which does not enter the first waveguide layer 51 when passing through the second optical element 511 of the first waveguide layer 51, is diffracted at the first optical element 510, and the diffracted light enters the first waveguide layer 51 and propagates in the form of total reflection. The optical path in the second waveguide layer 52 is: the image light propagated from the projection device or the previous waveguide layer is diffracted at the second optical element 511 of the first waveguide layer 51, and the diffracted light enters the first waveguide layer 51, the entered light is diffracted by the first optical element 510, and the diffracted light is emitted to the second waveguide layer 52, and the emitted light is diffracted at the second optical element 521 of the second waveguide layer 52, and the diffracted light enters the second waveguide layer 52 and propagates in the form of total reflection.

[0095] like Fig.16 As shown, the optical path in the first waveguide layer 51 is: light 2 is the 0th order light of light 1 in the second optical element 511 of the first waveguide layer 51, with an energy of 70%; light 3 is the diffracted light of incident light 2 in the first optical element 510 of the first waveguide layer 51, with an energy of 21%; light 4 is the 0th order light of light 2 in the first optical element 510 of the first waveguide layer 51, with an energy of 49%; light 5 is the diffracted light of light 3 in the second optical element 511 of the first waveguide layer 51, with an energy of 6.3%; light 6 is the diffracted light of light 5 in the first optical element 510 of the first waveguide layer 51, with an energy of 1.89%; light 7 is the 0th order light of light 5 in the first optical element 510 of the first waveguide layer 51, with an energy of 4.41%; light 8 is the diffracted light of light 3 in the second optical element 511 of the first waveguide layer 51, with an energy of 4. The 0th order light of the optical element 511 of the first waveguide layer 51 has an energy of 14.7%; the light 9 is the diffracted light of the light 6 in the second optical element 511 of the first waveguide layer 51, with an energy of 0.567%; the light 10 is the diffracted light of the light 8 in the first optical element 510 of the first waveguide layer 51, with an energy of 4.41%; the light 11 is the 0th order light of the light 6 in the second optical element 511 of the first waveguide layer 51, with an energy of 1.323%; the light 12 is the 0th order light of the light 8 in the first optical element 510 of the first waveguide layer 51, with an energy of 10.29%; the light 13 is the diffracted light of the light 9 in the first optical element 510 of the first waveguide layer 51, with an energy of 0.1701%; the light 14 is the 0th order light of the light 9 in the first optical element 510 of the first waveguide layer 51, with an energy of 0.3969%. The light 11, 12, and 13 are propagated by total reflection in the first waveguide layer 51.

[0096] The optical path in the second waveguide layer 52 is as follows: light 52' is the diffracted light of light 7 in the second optical element 521 of the second waveguide layer 52, with an energy of 1.323%; light 53' is the diffracted light of light 52' in the first optical element 520 of the second waveguide layer 52, with an energy of 0.3969%; light 54' is the 0th order light of light 52' in the first optical element 520 of the second waveguide layer 52, with an energy of 0.9261%. Light 54' propagates by total reflection in the second waveguide layer.

[0097] Please refer to Fig.17 , Fig.17 is a schematic diagram of the eighth optical path of the display device of this embodiment, the optical path in the first waveguide layer 51 is Fig.16 The optical paths in the first waveguide layer 51 are the same as shown. The optical paths in the second waveguide layer 52 are: light 52 is the 0th order light of light 7 in the second optical element 521 of the second waveguide layer 52, with an energy of 3.087%; light 53 is the diffracted light of light 52 in the first optical element 520 of the second waveguide layer 52, with an energy of 0.9261%; light 54 is the 0th order light of light 52 in the first optical element 520 of the second waveguide layer 52, with an energy of 2.1609%; light 55 is the 0th order light of light 53 in the first optical element 520 of the second waveguide layer 52, with an energy of 2.1609%; The diffracted light of the second optical element 521 has an energy of 0.27783%. Light 56 ​​is the diffracted light of light 55 in the first optical element 520 of the second waveguide layer 52, with an energy of 0.083349%. Light 57 is the 0th order light of light 55 in the first optical element 520 of the second waveguide layer 52, with an energy of 0.194481%. Light 58 is the 0th order light of light 53 in the second optical element 521 of the second waveguide layer 52, with an energy of 0.64827%. Lights 56 and 58 propagate by total reflection in the second waveguide layer.

[0098] Please refer to Fig.18 , Fig.18 is a ninth optical path schematic diagram of the display device of this embodiment, the optical path in the first waveguide layer 51 is Fig.16 The optical paths in the first waveguide layer 51 are the same as shown. The optical paths in the second waveguide layer 52 are as follows: light 62' is the diffracted light of light 10 in the second optical element 521 of the second waveguide layer 52, with an energy of 1.323%; light 63' is the diffracted light of light 62' in the first optical element 520 of the second waveguide layer 52, with an energy of 0.3969%; light 64' is the 0th order light of light 62' in the first optical element 520 of the second waveguide layer 52, with an energy of 0.9261%. Light 64' propagates in the second waveguide layer 52 by total reflection.

[0099] Please refer to Fig.19 , Fig.19 is a schematic diagram of the tenth optical path of the display device of this embodiment, the optical path in the first waveguide layer 51 is Fig.16The optical paths in the first waveguide layer 51 are the same as shown. The optical path in the second waveguide layer 52 is: light 62 is the 0th order light of light 10 in the second optical element 521 of the second waveguide layer 52, with an energy of 3.087%; light 63 is the diffracted light of light 62 in the first optical element 520 of the second waveguide layer 52, with an energy of 0.9261%; light 64 is the 0th order light of light 62 in the first optical element 520 of the second waveguide layer 52, with an energy of 2.1609%. Light 63 propagates by total reflection in the second waveguide layer.

[0100] Depend on Figures 10 to 19 It can be seen that 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, and the final total energy of the 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. Compared with the existing waveguide-based display device, the waveguide efficiency is improved by 143%, which greatly improves the utilization rate of light energy.

[0101] In the display device of the above specific implementation, the second optical element of each waveguide layer adopts a transmissive optical element based on the diffraction principle, and 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 may adopt a reflective optical element based on the diffraction principle, and the first optical element of each waveguide layer may adopt a transmissive optical element based on the diffraction principle. Please refer to Fig. 20 and Fig.21 , Fig. 20 The first optical element of the waveguide layer is a light path schematic diagram of a reflective optical element based on the diffraction principle, Fig.21 The second optical element of the waveguide layer is a schematic diagram of the optical path of a transmissive optical element based on the diffraction principle. In this implementation mode, the propagation optical path of the image light coupled into the waveguide layer through the first optical element and the second optical element is implemented accordingly.

[0102] In this embodiment, please refer to Fig. 9 As shown, 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 some waveguide layers from the first to the Nth waveguide layers 41 may be reflective optical elements based on the diffraction principle, and the first optical elements 410 of other waveguide layers may be transmissive optical elements based on the diffraction principle.

[0103] 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 waveguide layers from the first to the Nth waveguide layers 41 may be reflective optical elements based on the diffraction principle, and the second optical elements 411 of the other waveguide layers may be transmissive optical elements based on the diffraction principle.

[0104] Please refer to Fig. 9 In the second preset area of ​​each waveguide layer 41, a coupling-out portion 412 is provided for coupling the image light propagating in the waveguide layer 41 out to the user viewing side outside the waveguide layer 41. The image light coupled into the waveguide layer 41 propagates in the waveguide layer in the form of total reflection. The image light propagates in the turning area of ​​the waveguide layer in the form of total reflection. When propagating to the second preset area, it is coupled out by the coupling-out portion 412. The image light coupled out by each waveguide layer 41 enters the user's eyes to realize display. The coupling-out portion 412 can be an optical element based on the diffraction principle. In this embodiment, reference Fig. 9 As shown, the optical element 412 of the outcoupling part can be arranged on the side of the waveguide layer 41 away from the user. Alternatively, in other embodiments, the optical element of the outcoupling part can also be arranged on the side of the waveguide layer close to the user.

[0105] For further information, please refer to Fig. 9 In the second preset area of ​​each waveguide layer 41, an optical layer 413 is disposed on the side away from the user viewing, which absorbs the image light and allows light of other wavelengths except the image light to pass through. The specific implementation of the optical layer 413 can refer to the description of the first embodiment, and will not be repeated in this embodiment.

[0106] Preferably, the projections of the second preset areas of each waveguide layer 41 along the arrangement direction of the waveguide layers 41 do not overlap with each other, or the projections of the second preset areas of each waveguide layer 41 along the arrangement direction of the waveguide layers partially overlap. The purpose of such a setting is to avoid the second preset areas of each waveguide layer from completely overlapping. If the second preset areas of two waveguide layers completely overlap, the light coupled out of the latter waveguide layer will be incident on the coupling-out optical element of the second preset area of ​​the former waveguide layer and will be re-coupled into the waveguide layer. Therefore, through the above setting, the light can be coupled out as much as possible, and as much light as possible can be coupled out and enter the user's eyes, thereby improving the waveguide efficiency and the light energy utilization rate.

[0107] The above is a detailed introduction to a waveguide-based display device provided by the present invention. Specific examples are used herein to illustrate the principles and implementation methods of the present invention. The description of the above embodiments is only used to help understand the method of the present invention and its core idea. It should be pointed out that for ordinary technicians in this technical field, without departing from the principles of the present invention, several improvements and modifications can be made to the present invention, and these improvements and modifications also fall within the scope of protection of the claims of the present invention.

Claims

1. A waveguide-based display device, characterized in that: It includes an image projection device and a waveguide layer, wherein the image projection device is used to project image light; A coupling portion for coupling image light into the waveguide layer is provided in a first preset area of ​​the waveguide layer, and a coupling portion for coupling image light propagating in the waveguide layer out to a user viewing side outside the waveguide layer is provided in a second preset area of ​​the waveguide layer; An optical layer that absorbs image light and allows light of other wavelengths except image light to pass through is arranged on the second preset area of ​​the waveguide layer away from the user viewing side, and the coverage range of the optical layer is consistent with the second preset area of ​​the waveguide layer; The method comprises first to N waveguide layers, wherein the first to N waveguide layers are arranged in order from near to far from the projection device, and N is a positive integer greater than or equal to 2; A coupling portion for coupling image light into the waveguide layer is disposed in the first preset region of each waveguide layer, a coupling portion for coupling image light propagating in the waveguide layer out to a user viewing side outside the waveguide layer is disposed in the second preset region of each waveguide layer, and an optical layer that absorbs image light and allows light of other wavelengths except image light to pass through is disposed in the second preset region of each waveguide layer away from the user viewing side; The coupling portion of the first waveguide layer is specifically used to couple the image light projected by the projection device into the first waveguide layer, and the coupling portion of the i-th waveguide layer is specifically used to couple the image light that is not coupled into the previous waveguide layer and is transmitted from the first preset area of ​​the previous waveguide layer into the i-th waveguide layer, i∈[2,N]; The coupling-in portion comprises a first optical element arranged at a side of the first preset region of the waveguide layer away from the projection device and a second optical element arranged at a side of the first preset region of the waveguide layer close to the projection device; The image light transmitted from the projection device or the previous waveguide layer is diffracted by the second optical element of the current waveguide layer, and the diffracted light enters the current waveguide layer. 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, and the diffracted light formed by the diffraction is transmitted in the current waveguide layer in the form of total reflection; or / and, the image light propagated from the image projection device or the previous waveguide layer is diffracted by the second optical element of the current waveguide layer, and the diffracted light enters the current waveguide layer, the entered light is diffracted by the first optical element, and the diffracted light is emitted to the next waveguide layer, the emitted light is diffracted by the second optical element of the next waveguide layer, and the diffracted light enters the next waveguide layer and propagates in the form of total reflection; or / and, the light in the emitted light that passes through the second optical element of the next waveguide layer but does not enter the next waveguide layer is diffracted by the first optical element, the second optical element, and the first optical element in sequence, and the diffracted light formed is propagated in the next waveguide layer in the form of total reflection; or / and, the image light transmitted from the projection device or the previous waveguide layer is diffracted by the second optical element of the current waveguide layer, and the diffracted light enters the current waveguide layer, the entering light is reflected by the first optical element in sequence, and diffracted by the second optical element, and 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 and propagates in the form of total reflection; or / and, the light in the emitted light that passes through the second optical element of the next waveguide layer but does not enter the next waveguide layer is diffracted by the first optical element, and the diffracted light enters the next waveguide layer and propagates in the form of total reflection; or / and, among the image light rays propagated from the projection device or the previous waveguide layer, the light rays that do not enter the current waveguide layer when passing through the second optical element of the current waveguide layer are sequentially diffracted by the first optical element and the second optical element, and the diffracted light is emitted to the next waveguide layer through the first optical element, and the emitted light rays are diffracted by the second optical element of the next waveguide layer, and the diffracted light enters the next waveguide layer and propagates in the form of total reflection; or / and, among the emitted light rays that do not enter the next waveguide layer when passing through the second optical element of the next waveguide layer are sequentially diffracted by the first optical element, the second optical element, and the first optical element, and the diffracted light formed is propagated in the next waveguide layer in the form of total reflection; or / and, among the image light rays propagated from the projection device or the previous waveguide layer, the light rays that do not enter the current waveguide layer when passing through the second optical element of the current waveguide layer are diffracted by the first optical element, reflected by the second optical element, and diffracted by the first optical element in sequence, and the diffracted light is emitted to the next waveguide layer, and the emitted light rays are diffracted by the second optical element of the next waveguide layer, and the diffracted light enters the next waveguide layer and propagates in the form of total reflection; or / and, among the emitted light rays that do not enter the next waveguide layer when passing through the second optical element of the next waveguide layer are diffracted by the first optical element, and the diffracted light enters the next waveguide layer and propagates in the form of total reflection.

2. The waveguide-based display device according to claim 1, characterized in that The image light generated by the projection device has a wavelength band width of 0.1nm to 10nm, the absorption wavelength band width of the optical layer has a wavelength band width of 0.1nm to 10nm, and the absorption wavelength band range of the optical layer is consistent with the wavelength band range of the image light generated by the projection device.

3. The waveguide-based display device according to claim 1, characterized in that The optical layer is a narrow-band notch filter, and the light source of the projection device is a narrow-band projection light source; Alternatively, the projection device comprises a light emitting device that emits three primary color lasers respectively, and the central wavelength of the absorption band of the optical layer is consistent with the wavelength of the laser emitted by the light emitting device; Alternatively, the projection device includes a light emitting device for generating light and a filter element for filtering the light emitted by the light emitting device, and the wavelength range of the light allowed to pass by the filter element is consistent with the absorption band range of the optical layer.

4. The waveguide-based display device according to claim 1, characterized in that An air gap is provided between the optical layer and the waveguide layer.

5. The waveguide-based display device according to claim 4, characterized in that The air gap between the optical layer and the waveguide layer is 0.001 mm to 1 mm.

6. The waveguide-based display device of claim 1, wherein: The optical layer covers the substrate.

7. A waveguide-based display device according to any one of claims 1 to 6, characterized in that: The coupling-in portion comprises an optical element disposed at one side of the first preset region of the waveguide layer and coupling the image light into the waveguide layer; The coupling-out portion comprises an optical element disposed on one side of the second preset area of ​​the waveguide layer and coupling the image light out of the waveguide layer and close to the viewing side of the user.

8. The waveguide-based display device of claim 1, wherein: The first optical element of each waveguide layer is a reflective optical element based on the diffraction principle, or the first optical element of each waveguide layer is a transmissive optical element based on the diffraction principle; or the first optical elements of some waveguide layers from the first to the Nth waveguide layers are reflective optical elements based on the diffraction principle, and the first optical elements of the other waveguide layers are transmissive 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 some waveguide layers from the 1st to the 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.

9. The waveguide-based display device of claim 1, wherein: The projections of the second preset regions of the waveguide layers along the arrangement direction of the waveguide layers do not overlap with each other, or the projections of the second preset regions of the waveguide layers along the arrangement direction of the waveguide layers partially overlap with each other.

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