Near-to-eye display equipment
By designing a stray light suppression structure on the frame and using refractive index matching materials and tilted sides to guide image light to the outside, the problem of stray light at the end of the waveguide sheet is solved, thereby improving image contrast and image quality and providing an immersive visual experience.
Patent Information
- Application Number
- CN202511461457.7
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-10-14
- Publication Date
- 2025-12-02
AI Technical Summary
In existing augmented reality display systems, stray light is generated by the reflection of image light at the end of the waveguide sheet, which leads to a decrease in image contrast and a deterioration in image quality.
A stray light suppression structure is designed on the frame, and a refractive index matching material is connected to the end of the waveguide. By tilting the side, the image light is directionally reflected or controllably scattered to the outside of the waveguide, thus suppressing the formation of stray light.
Significantly improves image contrast and quality, providing clearer tonal gradations and sharper edges, enhancing the user's visual experience.
Smart Images
Figure CN121050101A_ABST
Abstract
Description
Technical Field
[0001] This application relates to the field of optical technology, and more particularly to a near-eye display device. Background Technology
[0002] Augmented reality is a technology that blends the real world with virtual information. Augmented reality display systems typically include micro-projectors and optical displays. The micro-projectors provide virtual display content for the augmented reality display system, which is then projected onto the viewer's eyes through the optical displays. The optical displays are usually transparent optical components, so that users can also see the real world through the optical displays at the same time.
[0003] However, when the image light travels through the waveguide to the end of the waveguide, it is reflected at the end to form stray light that returns to the waveguide. This stray light then exits along with the original image light, which may reduce the contrast of the observed image, thereby degrading the image quality and affecting the imaging effect. Summary of the Invention
[0004] This application provides a near-eye display device that can suppress stray light from image rays reaching the end of a waveguide from returning into the waveguide, thereby improving image contrast and optimizing image quality.
[0005] A near-eye display device includes a waveguide sheet and a lens frame. The waveguide sheet includes an insertion structure and an exit structure. The lens frame includes a stray light suppression structure. The end of the waveguide sheet is connected to the stray light suppression structure through a refractive index matching material. The stray light suppression structure includes at least one inclined side surface, which forms an acute angle with the plane containing the working surface of the waveguide sheet.
[0006] In practice, the refractive index of the refractive index matching material is matched with the refractive index of the waveguide sheet.
[0007] In practice, the refractive index of the waveguide sheet is in the range of 1.7-2.8; and the refractive index of the refractive index matching material is in the range of 1.5-2.0.
[0008] In practice, the stray light suppression structure has two opposing inclined sides of equal length, both of which are used to receive image light transmitted in the waveguide and reflect or scatter the image light to the outside of the waveguide.
[0009] Implementably, there is an arcuate transition between the two inclined sides.
[0010] In practice, the inclined side is a curved surface, and the angle between the tangent of the curved surface and the plane containing the working surface of the waveguide gradually decreases in the direction away from the waveguide.
[0011] Implementably, the surface of the inclined side is smooth to reflect image light incident on the inclined side.
[0012] Implementably, the acute angle ranges from 20° to 80°.
[0013] In practice, the thickness of the stray light suppression structure gradually increases from one end connected to the waveguide sheet to the other end.
[0014] In practice, the inclined side surface is provided with a plurality of continuous micro-inclined surfaces, and the included angle between two adjacent micro-inclined surfaces is 2° to 10°.
[0015] This application provides an innovative solution to the technical pain point of stray light reflection from the waveguide end in traditional near-eye display systems, which leads to decreased image contrast and degraded image quality. The solution proposes a novel approach that does not require altering the waveguide's structural form. This solution shifts the focus of optimization from the waveguide to the lens assembly: a specially designed stray light suppression structure on the lens assembly is optically connected to the waveguide end using a refractive index-matching material. Furthermore, the stray light suppression structure has at least one tilted side, which forms a specific acute angle with the waveguide's working surface. This allows incident image light to undergo directional reflection or controlled scattering on the tilted side, guiding it to the outside space of the waveguide. This suppresses stray light from returning to the waveguide end, significantly reducing stray light interference. This results in clearer tonal gradations and sharper edges in the observed image, ultimately improving image contrast and overall image quality, providing users with a more immersive and realistic visual experience. Attached Figure Description
[0016] To more clearly illustrate the technical solutions in the embodiments of this application, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.
[0017] Figure 1 This is a schematic diagram of a near-eye display device provided in one embodiment of this application;
[0018] Figure 2 This is a partial schematic diagram of a near-eye display device provided in one embodiment of this application;
[0019] Figure 3 A partial schematic diagram of a near-eye display device provided in another embodiment of this application;
[0020] Figure 4 A partial schematic diagram of a near-eye display device provided in another embodiment of this application;
[0021] Attached image labels:
[0022] 100, Near-eye display devices;
[0023] 110, waveguide plate; 111, coupling structure; 112, coupling structure;
[0024] 120, frame; 121, stray light suppression structure;
[0025] 130, refractive index matching material. Detailed Implementation
[0026] To enable those skilled in the art to better understand the present application, the technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present application, and not all embodiments. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative effort should fall within the scope of protection of the present application.
[0027] It should be noted that the terms "first," "second," etc., in the specification, claims, and accompanying drawings of this application are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that such data can be interchanged where appropriate so that the embodiments of this application described herein can be implemented in orders other than those illustrated or described herein. Furthermore, the terms "comprising" and "having," and any variations thereof, are intended to cover non-exclusive inclusion; for example, a process, method, system, product, or apparatus that comprises a series of steps or units is not necessarily limited to those steps or units explicitly listed, but may include other steps or units not explicitly listed or inherent to such processes, methods, products, or apparatus.
[0028] According to one aspect of this application, a near-eye display device is provided, the near-eye display device including a waveguide sheet and a lens frame, the waveguide sheet including an insertion structure and an exit structure, the lens frame including a stray light suppression structure, the end of the waveguide sheet being connected to the stray light suppression structure through a refractive index matching material, the stray light suppression structure including at least one inclined side surface, the inclined side surface forming an acute angle with the plane where the working surface of the waveguide sheet is located.
[0029] Specifically, the near-eye display device includes a waveguide sheet and a frame. The waveguide sheet is used for light transmission and imaging in the near-eye display device. It has an input structure and an output structure. The input structure guides the image light emitted by the optomechanical components into the waveguide sheet for transmission. The image light is transmitted back and forth between two surfaces of the waveguide sheet by total internal reflection. These two surfaces are the working surfaces of the waveguide sheet. The output structure guides the image light transmitted in the waveguide sheet out of the waveguide sheet, thus entering the human eye for imaging. The input and output structures can be geometric optical elements or diffractive optical elements.
[0030] The frame of the near-eye display device serves as a support and allows for wearing of the device.
[0031] Furthermore, a stray light suppression structure is provided on the frame. The end of the waveguide is connected to the stray light suppression structure via a refractive index matching material. This utilizes the refractive index matching material to achieve optical connection between the stray light suppression structure and the end of the waveguide. Since the refractive index of the refractive index matching material is close to that of the waveguide, the loss of image light at the interface between the waveguide and the refractive index matching material is reduced. This allows image light that might otherwise generate stray light at the end of the waveguide to be efficiently and with low loss coupled into the refractive index matching material and incident on the stray light suppression structure. The stray light suppression structure includes at least one inclined side, which forms an acute angle with the working plane of the waveguide. Thus, when image light is incident on the stray light suppression structure, it is primarily incident on the inclined side. The angle between the inclined side and the working plane of the waveguide allows the image light to undergo directional reflection or controlled scattering on this inclined side before exiting into the external space of the waveguide.
[0032] In practice, refractive index matching between the refractive index of the refractive index matching material and the refractive index of the waveguide sheet means that the refractive index of the refractive index matching material is close to that of the waveguide sheet, and the smaller the difference between the two refractive indices, the better. For example, the difference between their refractive indices should be less than 0.3. It can be understood that the closer the refractive index of the refractive index matching material is to that of the waveguide sheet, the lower the loss of image light at the interface between the waveguide sheet and the refractive index matching material. Refractive index matching materials are usually low-haze resins. To be suitable for the long-term operating environment of the equipment, high bonding strength and temperature and aging resistance must also be considered. These resins are generally modified by nanoparticle doping to increase the refractive index. However, due to the limitations of current material technology, the achievable limit of the refractive index of the waveguide sheet is greater than the limit of the refractive index matching material. When a material with a high refractive index is selected for the waveguide sheet, it may not be possible to find a more suitable refractive index matching material at present. However, it is not ruled out that refractive index matching materials with higher refractive indices may be developed in the future. At that time, the refractive index matching degree between the two will be further improved, and the difference in refractive indices can also be less than 0.3, and the interface transmission loss will be controlled at a lower level.
[0033] Specifically, the refractive index of the waveguide sheet can range from 1.7 to 2.8; if silicon carbide is used as the material for the waveguide sheet, the refractive index can reach 2.6 to 2.8; the refractive index of the refractive index matching material can range from 1.5 to 2.0, or even higher.
[0034] For example, refer to Figure 1 This figure illustrates a schematic diagram of a near-eye display device according to an embodiment of this application. As can be seen, the near-eye display device 100 includes a waveguide 110 and a lens frame 120. The waveguide 110 is provided with an insertion structure 111 and an exit structure 112, and the lens frame 120 is provided with a stray light suppression structure 121. The end of the waveguide 110 is connected to the stray light suppression structure 121 via a refractive index matching material 130. In this example, the waveguide 110 is implemented as a diffraction waveguide. Image light is incident on the insertion structure 111. Due to the diffraction effect of the insertion structure 111, different diffraction orders propagate in different directions. After these diffraction orders of light are incident on the end of the waveguide 110, the image light that originally formed stray light at the end of the waveguide 110 is coupled into the refractive index matching material 130 and incident on the inclined side of the stray light suppression structure 121. After directional reflection on this inclined side, it exits into the external space of the waveguide 110.
[0035] In this application, the stray light suppression structure may include one or more inclined sides. The inclined sides may be planar or curved. The inclined sides may be directly connected or transitioned through curved surfaces. Several examples are given below to illustrate this.
[0036] In practice, the stray light suppression structure has two opposing inclined sides of equal length, both of which are used to receive image light transmitted in the waveguide and reflect or scatter the image light to the outside of the waveguide.
[0037] For example, refer to Figure 1 and Figure 2 , Figure 2 A partial schematic diagram of a near-eye display device according to an embodiment is shown, specifically including a cross-sectional view of a stray light suppression structure 121. It can be seen that the stray light suppression structure 121 has two opposing inclined sides of equal length. Both inclined sides are planar. Figure 1 The two inclined sides are directly connected, and the cross-sectional shape of the stray light suppression structure 121 is an isosceles triangle. Figure 2 There is an arc transition between the two inclined sides. Both inclined sides of the stray light suppression structure are used to receive image light transmitted in the waveguide and reflect or scatter the image light to the outside of the waveguide.
[0038] For example, refer to Figure 3 , Figure 3A partial schematic diagram of a near-eye display device provided in an embodiment is shown, specifically including a cross-sectional view of a stray light suppression structure 121. It can be seen that the stray light suppression structure 121 has an inclined side surface, and the inclined side surface is a plane.
[0039] In practice, the inclined side is a curved surface, and the angle between the tangent of the curved surface and the plane containing the working surface of the waveguide gradually decreases in the direction away from the waveguide.
[0040] For example, refer to Figure 4 , Figure 4 A partial schematic diagram of a near-eye display device provided in an embodiment is shown, specifically including a cross-sectional view of a stray light suppression structure 121. It can be seen that the stray light suppression structure 121 has an inclined side surface, which is a curved surface. The angle α between the tangent of the curved surface and the plane where the working surface of the waveguide plate is located gradually decreases in the direction away from the waveguide plate.
[0041] Implementably, the surface of the inclined side is smooth to reflect the image light incident on the inclined side.
[0042] Specifically, from an optical mechanism perspective, the smoothness of the inclined surface affects the proportion of incident image light interacting with it. When the surface roughness meets certain conditions, specular reflection dominates the interaction of light on the surface, and scattering can be controlled to below 5%. Otherwise, scattering will occur, with the propagation direction of scattered light being random and highly uncontrollable. Some scattered light may remain inside the device, posing a risk of secondary stray light. Of course, from a technical perspective, controllable scattering of stray light can also be achieved through a special design of the stray light suppression structure. This involves adjusting the direction, intensity, and range of scattering to prevent the scattered stray light from flowing back to the coupling structure. However, this approach is more complex than "directional reflection."
[0043] Furthermore, to reduce the trace amounts of reflected light that may remain during the specular reflection process on the tilted side, the tilted side can be blackened: a matte black optical coating can be used, or a low-reflection film layer can be formed on the surface through a chemical blackening process. This combination of a "highly smooth surface + blackening treatment" design not only allows for the directional export of stray light through specular reflection but also eliminates secondary interference from residual reflected light through low-reflection treatment, forming a dual guarantee. This more thoroughly blocks the stray light return path, providing more reliable optical conditions for improving image contrast.
[0044] In practice, the acute angle ranges from 20° to 80°.
[0045] It is understandable that in the stray light suppression design of near-eye display devices, the acute angle between the tilted side of the stray light suppression structure and the working surface of the waveguide is not a random value, but a key parameter based on the propagation characteristics of image light within the waveguide, the law of optical reflection, and the overall structural layout of the device. Its core objective is to accurately match the transmission angle of image light within the waveguide, so that when image light is incident on the tilted side, it can be led out along a preset path, rather than forming a secondary reflection inside the structure or device.
[0046] Specifically, the angle between the tilted side of the stray light suppression structure and the working surface of the waveguide is specially designed to cause directional reflection or controlled scattering of image light incident on the tilted side, guiding the image light to the external space of the waveguide. Practically, a value α between the tilted side of the stray light suppression structure and the working surface of the waveguide achieves better results when it is between 20° and 80°. From an optical principle perspective, if the angle is too small (e.g., less than 20°), the angle at which the image light is incident on the tilted side will be too gentle, potentially causing the reflected light to have an excessively small angle with the working surface of the waveguide, thus impacting the inner wall of the frame or the edge of the waveguide. This secondary reflection still carries the risk of backflow to the coupling structure. If the angle is too large (e.g., greater than 80°), the angle of incidence of the image light is too steep, and the reflected light is likely to be directed towards the internal optomechanical components or other structures of the equipment. Similarly, stray light interference may occur due to component reflection, making complete elimination impossible.
[0047] In practice, the thickness of the stray light suppression structure gradually increases from the end connected to the waveguide sheet to the other end.
[0048] Specifically, in this application, a stray light suppression structure is disposed on the frame, and the thickness of the stray light suppression structure is set to gradually increase from the end connected to the waveguide to the other end, which can better guide the image light to the external space of the waveguide. Moreover, the structure with the gradually thickening end can enhance its mechanical strength, ensuring that it is not easily deformed by external forces during the wearing of the frame, while providing a more stable base for the processing of the tilted side. Ultimately, a balance is formed between optical performance and structural reliability, which more effectively prevents stray light from flowing back to the waveguide and ensures the stability of image quality.
[0049] In practice, the inclined side is provided with a number of continuous micro-inclined surfaces, and the included angle between two adjacent micro-inclined surfaces is 2° to 10°.
[0050] In some embodiments, the tilted sides of the stray light suppression structure are not designed as a single plane, but rather consist of several continuously connected micro-tilted surfaces along the direction of image light propagation. These micro-tilted surfaces are arranged in a stepped or smoothly transitioned manner. Each micro-tilted surface maintains an acute angle with the working surface of the waveguide sheet, and the angle between the surface tangents of two adjacent micro-tilted surfaces is controlled within the range of 2° to 10°. Compared to a single tilted surface, continuous micro-tilted surfaces provide a certain improvement in stray light suppression, thereby enhancing image quality stability and user experience.
[0051] This application provides an innovative solution to the technical pain point of stray light reflection from the waveguide end in traditional near-eye display systems, which leads to decreased image contrast and degraded image quality. The solution proposes a novel approach that does not require altering the waveguide's structural form. This solution shifts the focus of optimization from the waveguide to the lens assembly: a specially designed stray light suppression structure on the lens assembly is optically connected to the waveguide end using a refractive index-matching material. Furthermore, the stray light suppression structure has at least one tilted side, which forms a specific acute angle with the waveguide's working surface. This allows incident image light to undergo directional reflection or controlled scattering on the tilted side, guiding it to the outside space of the waveguide. This suppresses stray light from returning to the waveguide end, significantly reducing stray light interference. This results in clearer tonal gradations and sharper edges in the observed image, ultimately improving image contrast and overall image quality, providing users with a more immersive and realistic visual experience.
[0052] The specific embodiments described above do not constitute a limitation on the scope of protection of this application. Those skilled in the art should understand that various modifications, combinations, sub-combinations, and substitutions can be made according to design requirements and other factors. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of this application should be included within the scope of protection of this application.
Claims
1. A near-eye display device, characterized in that, The near-eye display device includes a waveguide sheet and a lens frame. The waveguide sheet includes an insertion structure and an exit structure. The lens frame includes a stray light suppression structure. The end of the waveguide sheet is connected to the stray light suppression structure through a refractive index matching material. The stray light suppression structure includes at least one inclined side, which forms an acute angle with the plane where the working surface of the waveguide sheet is located.
2. The near-eye display device according to claim 1, characterized in that, The refractive index of the refractive index matching material is matched with the refractive index of the waveguide sheet.
3. The near-eye display device according to claim 2, characterized in that, The refractive index of the waveguide sheet ranges from 1.7 to 2.8; the refractive index of the refractive index matching material ranges from 1.5 to 2.
0.
4. The near-eye display device according to claim 1, characterized in that, The stray light suppression structure has two opposite inclined sides of the same length. Both inclined sides are used to receive image light transmitted in the waveguide and reflect or scatter the image light to the outside of the waveguide.
5. The near-eye display device according to claim 4, characterized in that, There is an arc-shaped transition between the two inclined sides.
6. The near-eye display device according to claim 1, characterized in that, The inclined side is a curved surface, and the angle between the tangent of the curved surface and the plane containing the working surface of the waveguide gradually decreases in the direction away from the waveguide.
7. The near-eye display device according to claim 4 or 6, characterized in that, The surface of the inclined side is smooth to reflect the image light incident on the inclined side.
8. The near-eye display device according to claim 1, characterized in that, The acute angle ranges from 20° to 80°.
9. The near-eye display device according to claim 1, characterized in that, The thickness of the stray light suppression structure gradually increases from the end connected to the waveguide sheet to the other end.
10. The near-eye display device according to claim 1, characterized in that, The inclined side surface is provided with a number of continuous micro-inclined surfaces, and the included angle between two adjacent micro-inclined surfaces is 2° to 10°.