Display system and head-mounted display device

Abstract

The invention provides a display system. The display system comprises an optical engine, a super lens, a first optical waveguide and a second optical waveguide. The light engine is used for emitting colored image light. The super lens is located on the side, where the light engine emits the image light, of the light engine and comprises a substrate and a super surface formed on the substrate, the super surface is used for receiving and splitting the image light so as to emit at least a first light beam and a second light beam, and the first light beam and the second light beam have different colors. The first optical waveguide and the second optical waveguide are arranged in a stacked mode and are located on the side, where the first light beam and the second light beam are emitted, of the super lens. The second optical waveguide is used for transmitting and outputting the second light beam towards the first optical waveguide, and the first optical waveguide is used for transmitting the first light beam and outputting the combined light of the first light beam and the second light beam to a target area so as to jointly display an image. The invention also provides a head-mounted display device.

Description

Technical Field

[0001] This application relates to the field of augmented reality technology, and more particularly to a display system and a head-mounted display device including the display system. Background Technology

[0002] Currently, traditional color diffractive waveguide systems mainly employ double- or triple-layer waveguide stacking technology. Each waveguide layer couples and transmits light of a single color, and the light of a single color transmitted by each waveguide layer is finally combined in the waveguide layer closest to the wearer's eye before being output to the area that the wearer's eye can receive.

[0003] Please refer to Figure 7 A conventional color diffractive waveguide system uses three optical engines 11A, each of which emits light of a single color (first beam LP1A, second beam LP2A, and third beam LP3A) into three waveguides (first waveguide 131A, second waveguide 132A, and third waveguide 133A). The light emitted by the three optical engines 11A has different colors. The coupling gratings (first coupling grating 131aA, second coupling grating 132aA, and third coupling grating 133aA) of the three waveguide layers are spatially staggered (i.e., the projections of the coupling gratings along the waveguide thickness direction do not overlap). Three optical engines 11A are correspondingly positioned one-to-one with the coupling gratings of the three waveguide layers. Light of three colors is coupled into the waveguide through coupling gratings designed for their respective wavelengths for total internal reflection. In this way, each waveguide layer is used only to receive and transmit light emitted by one optical engine, avoiding cross-diffraction and color crosstalk caused by two or more beams of different colors propagating within the same waveguide. However, this traditional color diffraction waveguide technology, using three optical engines 11A, significantly increases the overall size of the device, hindering miniaturization. Please refer to [reference needed]. Figure 8 Another traditional color diffractive waveguide system, in order to reduce the size of the device, uses an optical engine 11B to emit colored image light LPB into three waveguides (first waveguide 131B, second waveguide 132B, and third waveguide 133B). The coupling gratings of the three waveguides (first coupling grating 131aB, second coupling grating 132aB, and third coupling grating 133aB) are spatially stacked (i.e., the projections of the coupling gratings of the three waveguides overlap along the waveguide thickness direction). The colored image light contains light rays of different colors (first beam LP1B, second beam LP2B, and third beam LP3B) which are diffracted by the coupling gratings on different waveguides before being transmitted in the corresponding waveguides. However, this design may cause two or more beams of light with different colors to enter the same waveguide for transmission, thus generating color crosstalk. Summary of the Invention

[0004] In view of this, this application provides a display system and a head-mounted display device that can reduce size while improving color crosstalk.

[0005] This application provides a display system comprising a light engine, a superlens, a first optical waveguide, and a second optical waveguide. The light engine emits colored image light. The superlens, located on the side of the light engine from which the image light is emitted, includes a substrate and a metasurface formed on the substrate. The metasurface receives and splits the image light to emit at least a first beam and a second beam, the first beam and the second beam having different colors. The first and second optical waveguides are stacked and both are located on the side of the superlens from which the first and second beams are emitted. The second optical waveguide conducts and outputs the second beam toward the first optical waveguide, and the first optical waveguide conducts the first beam and outputs the combined light of the first and second beams to a target area.

[0006] In the display system provided in this application, a superlens is used to split the colored image light into a first beam and a second beam before emission. A first optical waveguide and a second optical waveguide are used to receive and transmit the first and second beams, respectively, and the first optical waveguide also outputs the combined light of the first and second beams to the target area. Since the first and second beams are transmitted in their respective optical waveguides, it helps prevent cross-diffraction when different colors of light are transmitted in the same optical waveguide, thereby improving color crosstalk. Furthermore, the display system of this application uses a single light engine to emit the colored image light, which helps to reduce the size of the display system.

[0007] A second aspect of this application provides a head-mounted display device, including a frame and a display system as described in any of the above embodiments. A mounting position is provided on the frame. In the display system as described in any of the above embodiments, the first optical waveguide and the second optical waveguide are fixedly disposed in the mounting position, and the optical engine is embedded within the frame.

[0008] The aforementioned head-mounted display device integrates the aforementioned display system, enabling it to achieve all the beneficial effects of the aforementioned display system. Attached Figure Description

[0009] Figure 1 This is a three-dimensional structural diagram of a head-mounted display device according to an embodiment of this application.

[0010] Figure 2 This is a three-dimensional structural diagram of the display system according to an embodiment of this application.

[0011] Figure 3 for Figure 2 A schematic diagram of the planar structure of the display system.

[0012] Figure 4 A flowchart for determining the metasurface pattern of a superlens.

[0013] Figure 5 This is a schematic diagram of the planar structure of a display system according to another embodiment of this application.

[0014] Figure 6 This is a schematic diagram of the planar structure of a display system according to another embodiment of this application.

[0015] Figure 7 This is a schematic diagram of a traditional color diffractive waveguide system.

[0016] Figure 8 This is a schematic diagram of another traditional color diffractive waveguide system.

[0017] Explanation of main component symbols Head-mounted display devices: 100 Display systems: 10, 10a, 10b, 10c Light Engines: 11, 11A, 11B Light emission array: 110 Collimating lens: 111 Superlens: 12 Base: 121 Metasurface: 122 Waveguide structure: 13 First optical waveguide: 131, 131A, 131B First coupling grating: 131a, 131aA, 131aB First coupling grating: 131b First waveguide: 131c Second optical waveguide: 132, 132A, 132B Second coupling grating: 132a, 132aA, 132aB Second coupling grating: 132b Second waveguide: 132c Third optical waveguide: 133, 133A, 133B Third coupling grating: 133a, 133aA, 133aB Third coupling grating: 133b Third waveguide: 133c Diagonal grating: 14 Frame: 20 Installation position: 21 Image light: LP, LPB First beam: LP1, LP1A, LP1B Second beam: LP2, LP2A, LP2B Third beam: LP3, LP3A, LP3B Steps: S1~S3 The following detailed description, in conjunction with the accompanying drawings, will further illustrate this application. Detailed Implementation

[0018] The technical solution of this application will be clearly and completely described below with reference to the embodiments of this application. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments.

[0019] It should be noted that when a component is considered to be "set on" another component, it can be directly set on the other component or may have an intervening component present. The term "and / or" as used herein includes all and any combination of one or more of the associated listed items. The terminology used in this application's specification is for the purpose of describing particular embodiments only and is not intended to be limiting of the application.

[0020] To further illustrate the technical means and effects adopted by this application in achieving its intended purpose, the following detailed description of this application is provided in conjunction with the accompanying drawings and preferred embodiments.

[0021] Please see Figure 1 The head-mounted display device 100 of this application embodiment includes a display system 10 and a frame 20. A mounting position 21 is provided on the frame 20. The display system 10 includes a waveguide structure 13 and a light engine 11. The light engine 11 is embedded within the frame 20 and is used to emit colored image light. The waveguide structure 13 is fixedly disposed in the mounting position 21 and is used to receive and conduct image light. When a user wears the head-mounted display device 100, the waveguide structure 13 can conduct image light to the user's eyes, allowing the user to see a colored image.

[0022] The head-mounted display device 100 includes two display systems 10. Each display system 10 includes a waveguide structure 13 and a light engine 11. One of the two display systems 10 provides an image to the user's left eye, and the other provides an image to the user's right eye. In other embodiments, the head-mounted display device 100 includes a single display system 10 for simultaneously providing images to the user's left and right eyes.

[0023] In at least one embodiment, the head-mounted display device 100 is augmented reality (AR) glasses. The frame 20 is a glasses frame, and mounting positions 21 are provided on the two frames of the frame. The waveguide structures 13 of the two display systems 10 are respectively disposed in the mounting positions 21 of the left and right frames, and the light engines 11 of the two display systems 10 are respectively embedded in the left and right temples near the frames.

[0024] The two display systems 10 have basically the same structure and function. The following description will use one of the display systems 10 as an example.

[0025] Please refer to the following: Figure 2 and Figure 3 The display system 10a of the first embodiment of this application includes a light engine 11, a waveguide structure 13, and a superlens 12. The superlens 12 is located on the side of the light engine 11 from which the image light LP is emitted, and is used to split the image light LP to emit at least a first beam LP1 and a second beam LP2. The first beam LP1 and the second beam LP2 have different colors; the first beam LP1 is blue light and the second beam LP2 is red light. In other embodiments, the first beam LP1 is red light and the second beam LP2 is green light, or the first beam LP1 is blue light and the second beam LP2 is red light. The waveguide structure 13 is located on the side of the superlens 12 from which the first beam LP1 and the second beam LP2 are emitted, and is used to conduct the first beam LP1 and the second beam LP2 and to combine the light from the first beam LP1 and the second beam LP2 and output it to the target area. The "target area" refers to the area where the user's eyes can receive light, i.e., the user's eyebox area.

[0026] The light engine 11 includes a light-emitting array 110 and a collimating lens 111. The light-emitting array 110 emits image light LP. The light-emitting array 110 can be a micro light-emitting diode (micro LED) array. The collimating lens 111 is located on one side of the image light LP emitted from the light-emitting array 110, and is used to collimate the image light LP into a parallel beam before it is emitted, so that the first beam LP1, the second beam LP2, and the third beam LP3 emitted after the superlens 12 splits the image light LP are also parallel beams. The first beam LP1 and the second beam LP2 are incident parallel to each other in different directions into the first optical waveguide 131 and the second optical waveguide 132, which helps to stably transmit the first beam LP1 and the second beam LP2 in the first optical waveguide 131 and the second optical waveguide 132, respectively, and improves the light transmission efficiency of the first optical waveguide 131 and the second optical waveguide 132.

[0027] The waveguide structure 13 includes a first optical waveguide 131 and a second optical waveguide 132 stacked together, both located on the side from which the first beam LP1 and the second beam LP2 emerge from the superlens 12. The first optical waveguide 1311 is located between the superlens 12 and the second optical waveguide 132. The second optical waveguide 132 is used to conduct and output the second beam LP2 toward the first optical waveguide 131, while the first optical waveguide 131 is used to conduct the first beam LP1 and to combine the first beam LP1 and the second beam LP2 and output them to the target area.

[0028] The first optical waveguide 131 includes a first coupling grating 131a, a first coupling grating 131b, and a first waveguide 131c. The first coupling grating 131a is used to couple the first beam LP1 into the first waveguide 131c, the first waveguide 131c is used to transmit the first beam LP1 toward the location of the first coupling grating 131b, and the first coupling grating 131b is used to couple the first beam LP1 out to the target area.

[0029] The second optical waveguide 132 includes a second coupling grating 132a, a second coupling grating 132b, and a second waveguide 132c. The second coupling grating 132a couples the second beam LP2 into the second waveguide 132c. The second waveguide 132c transmits the second beam LP2 toward the location of the second coupling grating 132b. The second coupling grating 132b couples the second beam LP2 out of the second waveguide 132c. Since the orthographic projection of the second coupling grating 132b onto the first waveguide 131c coincides with the first coupling grating 131b, the second beam LP2 emitted from the second coupling grating 132b is incident on the first coupling grating 131b. After passing through the first waveguide 131c and the first coupling grating 131b, the second beam LP2 combines with the first beam LP1 and is output to the target area.

[0030] The orthographic projection of the second coupling grating 142 onto the first waveguide 131c is spaced apart from that of the first coupling grating 131a. This helps prevent some of the second beam LP2 from entering the first waveguide 131c after diffraction by the first coupling grating 131a, causing cross-diffraction with the first beam LP1 and resulting in color crosstalk. By staggering the coupling gratings located on different waveguides, it helps ensure that each optical waveguide transmits a beam of one color, thereby reducing the possibility of color crosstalk. The orthographic projection of the second output grating 132b onto the first waveguide 131c coincides with that of the first output grating 131b. This helps ensure that the exit directions of beams of different colors (the first beam LP1 and the second beam LP2) are consistent, so that the beams of different colors almost completely overlap after exiting the first optical waveguide 131. This helps avoid color difference and results in a better image quality after the beams of different colors are combined.

[0031] The display system 10a also includes two deflection gratings 14, which are respectively disposed on the surfaces of the first optical waveguide 131 and the second optical waveguide 132. Each deflection grating 14 is used to change the propagation path of the light beam in the optical waveguide, causing the light beam to deflect and guide the light beam to the corresponding output grating, and finally exit from the output grating.

[0032] Please see Figure 3 The superlens 12 is located on the surface of the first waveguide 131c near the optical engine 11, and the first coupling grating 131a is located on the surface of the first waveguide 131c away from the optical engine 11, and the first coupling grating 131a is a reflective grating. The superlens 12 includes a substrate 121 and a metasurface 122 formed on the substrate 121. The metasurface 122 is located on the side of the substrate 121 away from the first optical waveguide 131, and the metasurface 122 is integrally formed with the substrate 121. In some embodiments, the superlens 12 is made of a material with dielectric properties in the visible light range, including silicon nitride, gallium nitride, or titanium oxide.

[0033] Multiple subwavelength structural units are disposed on the metasurface 122. These subwavelength structural units are formed on the substrate 121 using nano-imprint lithography (NIL). Each subwavelength structural unit is configured to phase-modulate light of different colors, so that different colors of light are transmitted in different directions after passing through the metasurface 122. Each subwavelength structural unit is a nanopillar or nanosheet structure. By adjusting parameters such as the shape of the cross-section of a single nanopillar or nanosheet, the height of a single nanopillar or nanosheet, and the distance between multiple nanopillars or nanosheets, the first beam LP1 and the second beam LP2 emitted from the superlens 12 are changed, ensuring that the first beam LP1 and the second beam LP2 are transmitted to the first coupling grating 131a and the second coupling grating 132a, respectively.

[0034] Please see Figure 4 The steps for determining the metasurface pattern of the superlens 12 include: Step S1: Preset the optical paths for beams of different colors; Step S2: Finite difference time-domain simulation software uses a genetic algorithm to simulate the optical paths of different colored beams emitted from the superlens when the metasurface of the superlens has different patterns. Step S3: Calculate the light intensity of different colored beams emitted from the superlens, determine whether the optical paths of the different colored beams emitted from the superlens are the same as the preset optical paths, and whether the light intensity of the different colored beams emitted from the superlens all reach the target value.

[0035] In step S1, the computer simulation software, based on the relative positions of the optical engine 11, the superlens, and the multiple coupling gratings, predetermines the optical paths of the multiple beams of different colors as the superlens splits the image light LP emitted from the optical engine 11 into multiple beams of different colors and transmits them to the corresponding coupling gratings. In some embodiments, the computer simulation software is Ansys Zemax or Ansys Lumerical FDTD.

[0036] In step S2, the metasurface of the superlens has different patterns representing parameters such as the shape of multiple subwavelength structural units on the metasurface, the height of a single subwavelength structural unit, the arrangement of multiple subwavelength structural units, and the distance between multiple subwavelength structural units. These differences cause changes in the phase modulation of the light beam by the metasurface, thus altering the optical paths of different colored light beams emitted from the superlens. Finite-difference time-domain simulation software adjusts these parameters to obtain the optical paths of the different colored light beams emitted from the superlens.

[0037] In step S3, the light intensity of different colored beams emitted from the superlens is calculated using finite difference time-domain simulation software, and the optical paths of the different colored beams emitted from the superlens are simulated. It is determined whether the simulated optical paths of the different colored beams emitted from the superlens are the same as the preset optical paths, and whether the light intensities of the different colored beams emitted from the superlens all reach the target value. When the simulated optical paths of the different colored beams emitted from the superlens are different from the preset optical paths, and the light intensity of at least one color beam does not reach the target value, step S2 is repeated until the simulated optical paths of the different colored beams emitted from the superlens are the same as the preset optical paths and the light intensity of each color beam reaches the target value. At this time, the superlens simulated in the finite difference time-domain simulation software is the superlens 12 required by the display system 10a.

[0038] In the aforementioned display system 10a, the colored image light LP is split into a first beam LP1 and a second beam LP2 by a superlens 12 before being emitted. The first beam LP1 is coupled through a first coupling grating 131a and enters the first waveguide 131c, then is conducted through the first waveguide 131c to the first coupling grating 131b, and finally is coupled out of the first optical waveguide 131 through the first coupling grating 131b. The second beam LP2 passes through the first optical waveguide 131, is coupled through a second coupling grating 132a and enters the second waveguide 132c, then is conducted through the second waveguide 132c to the second coupling grating 132b, and finally is coupled out of the second optical waveguide 132 through the second coupling grating 132b. After being coupled out of the second optical waveguide 132, the second beam LP2 passes through the first optical waveguide 131 and combines with the first beam LP1 before being output to the target area, thus allowing the user to see the colored image formed by the combination of the first beam LP1 and the second beam LP2. As can be seen from the above, the first optical waveguide 131 and the second optical waveguide 132 are used to receive and conduct the first beam LP1 and the second beam LP2, respectively, and the first optical waveguide 131 is also used to output the combined light of the first beam LP1 and the second beam LP2 to the target area. Since the first beam LP1 and the second beam LP2 are transmitted in their respective optical waveguides, it is beneficial to prevent cross-diffraction when different colors of light are transmitted in the same optical waveguide, thereby improving color crosstalk. Furthermore, the display system 10a uses a single light engine to emit colored image light, which helps to reduce the size of the display system.

[0039] Please see Figure 5 The display system 10b of the second embodiment of this application differs from the display system 10a in that the superlens 12 in the display system 10b is used to split the image light LP into a first beam LP1, a second beam LP2, and a third beam LP3 before emission. The first beam LP1 is red light, the second beam LP2 is green light, and the third beam LP3 is blue light. In other embodiments, the first beam LP1 is blue light, the second beam LP2 is green light, and the third beam LP3 is red light, or the first beam LP1 is red light, the second beam LP2 is blue light, and the third beam LP3 is green light.

[0040] The display system 10b also includes a third optical waveguide 133, located on the side of the second optical waveguide 132 away from the first optical waveguide 131. The third optical waveguide 133 includes a third coupling grating 133a, a third coupling grating 133b, and a third waveguide 133c. The orthographic projection of the third coupling grating 133a onto the first waveguide 131c is spaced apart from the orthographic projection of the second coupling grating 132a onto the first waveguide 131c and the first coupling grating 131a. The orthographic projection of the third coupling grating 133b onto the first waveguide 131c coincides with the orthographic projection of the second coupling grating 132b onto the first waveguide 131c and the first coupling grating 131b. The third coupling grating 133a is used to couple a third beam LP3 into the third waveguide 133c, and the third waveguide 133c is used to transmit the third beam LP3 toward the location of the third coupling grating 133b. Since the orthographic projection of the third coupling grating 133b onto the first waveguide 131c coincides with the orthographic projection of the second coupling grating 132b onto the first waveguide 131c and the first coupling grating 131b, the third beam LP3 emitted from the third coupling grating 133b enters the second coupling grating 132b. After passing through the second waveguide 132c and the second coupling grating 132b, the third beam LP3 combines with the second beam LP2 and is output together into the first optical waveguide 131. It then combines with the first beam LP1 and is output together to the target area. Compared to display system 10a, which includes a double-layer optical waveguide, display system 10b includes a triple-layer optical waveguide, allowing for the transmission of more color types of light, which is beneficial for improving the color saturation of the displayed image.

[0041] Please see Figure 6 The display system 10c of the third embodiment of this application differs from the display system 10b in that, in the display system 10c, the superlens 12 is located within the light engine 11. The light engine 11 includes a light-emitting array 110 but does not include a collimating lens. The light-emitting array 110 is used to emit image light LP. The superlens 12 is located on the side of the light-emitting array 110 from which the image light LP is emitted, and the metasurface 122 of the superlens 12 is located on the side of the substrate 121 near the first optical waveguide 131. Compared to the display system 10b, the superlens 12, in addition to splitting the image light LP, is also used to make the first beam LP1, the second beam LP2, and the third beam LP3 after splitting all become parallel beams before being emitted. That is, the superlens 12 is compatible with the function of the collimating lens. The display system 10c uses the superlens 12 instead of the collimating lens, reducing the size of the display system 10c and making the head-mounted display device 100 lighter.

[0042] Those skilled in the art should recognize that the above embodiments are only used to illustrate this application and are not intended to limit this application. Any appropriate changes and variations made to the above embodiments within the essential spirit and scope of this application fall within the scope of protection claimed in this application.

Claims

1. A display system, characterized in that, include: A light engine, used to emit colored image light; A superlens, located on the side of the optical engine emitting the image light, includes a substrate and a metasurface formed on the substrate. The metasurface receives and splits the image light to emit at least a first beam and a second beam, the first beam and the second beam having different colors; and A first optical waveguide and a second optical waveguide are stacked and both are located on the side from which the first beam and the second beam emerge from the superlens. The second optical waveguide is used to conduct and output the second beam toward the first optical waveguide. The first optical waveguide is used to conduct the first beam and output the combined beam of the first beam and the second beam to the target area to jointly display an image.

2. The display system as described in claim 1, characterized in that, The metasurface is located on the side of the substrate away from the first optical waveguide. Multiple subwavelength structural units are disposed on the metasurface. Each subwavelength structural unit is configured to perform phase modulation on light of different colors so that light of different colors is transmitted in different directions after passing through the metasurface.

3. The display system as described in claim 1, characterized in that, The first optical waveguide includes a first coupling grating, a first coupling grating, and a first waveguide. The first coupling grating is used to couple the first beam into the first waveguide and transmit it in the first waveguide in a direction close to the first coupling grating. The first coupling grating is used to output the first beam to the target area. The second optical waveguide includes a second coupling grating, a second coupling grating, and a second waveguide. The second coupling grating is used to couple the second beam into the second waveguide and transmit it in the second waveguide toward the direction of the second coupling grating. The second coupling grating is used to output the second beam to the area where the first coupling grating is located.

4. The display system as described in claim 3, characterized in that, The superlens is located on the surface of the first optical waveguide near the optical engine, and the first coupling grating is located on the surface of the first optical waveguide away from the optical engine.

5. The display system as described in claim 4, characterized in that, The first coupling grating is a reflection grating.

6. The display system as described in claim 3, characterized in that, The orthographic projection of the second coupling grating onto the first waveguide is spaced apart from the first coupling grating, and the orthographic projection of the second coupling grating onto the first waveguide coincides with the first coupling grating.

7. The display system as described in any one of claims 1 to 6, characterized in that, The light engine includes a light-emitting array and a collimating lens. The light-emitting array is used to emit the image light, and the collimating lens is located on the side of the light-emitting array from which the image light is emitted, and is used to collimate the image light into a parallel beam before it is emitted.

8. The display system as described in claim 1, characterized in that, The superlens is located within the optical engine, which includes a light-emitting array for emitting the image light. The superlens is located on the side of the light-emitting array from which the image light is emitted, and is used to split the image light into at least a first beam and a second beam, wherein the first beam and the second beam are both parallel beams.

9. The display system as described in claim 8, characterized in that, The metasurface is located on the side of the substrate close to the first optical waveguide. Multiple subwavelength structural units are disposed on the metasurface. Each subwavelength structural unit is configured to perform phase modulation on light of different colors so that light of different colors is transmitted along different spatial directions after passing through the metasurface.

10. The display system as claimed in claim 1, characterized in that, The display system further includes a third optical waveguide located on the side of the second optical waveguide away from the first optical waveguide; the metasurface is used to receive and split the image light to emit a first beam, a second beam, and a third beam, wherein the first beam, the second beam, and the third beam are of different colors. The third optical waveguide is used to conduct and output the third beam toward the second optical waveguide. The second optical waveguide is used to conduct the second beam and output the combined beam of the second beam and the third beam to the first optical waveguide. The first optical waveguide is used to conduct the first beam and output the combined beam of the first beam, the second beam and the third beam to the target area to jointly display an image.

11. A head-mounted display device, characterized in that, include: The frame has mounting positions. The display system as described in any one of claims 1 to 10, wherein the first optical waveguide and the second optical waveguide are fixedly disposed in the mounting position, and the optical engine is embedded in the frame.

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