Diffraction optical waveguide and display device
By designing a diffractive waveguide and optimizing light propagation through increasing grating height and multi-layer structure, the problem of uneven brightness in waveguide lenses was solved, improving the display efficiency and image uniformity of AR glasses, while reducing the size and weight of the device.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- Filing Date
- 2025-04-17
- Publication Date
- 2026-03-20
AI Technical Summary
Existing waveguide lenses suffer from uneven image brightness, resulting in low display efficiency for AR glasses.
Design a diffractive waveguide comprising a substrate layer and a grating layer stacked together, wherein at least two sets of first gratings are disposed in the light-emitting region, the height of the gratings increasing along the propagation direction, and combined with waveguide substrate layer, anti-reflection layer and reflective layer, to optimize the light propagation path and coupling efficiency.
It improves the uniformity of image brightness and enhances display efficiency, reduces stray light interference, and lowers the size and weight of AR glasses.
Smart Images
Figure CN224020016U_ABST
Abstract
Description
TECHNICAL FIELD
[0001] The utility model relates to display technical field especially, relate to a kind of diffractive optical waveguide and display equipment. BACKGROUND
[0002] Augmented Reality (AR) technology is a kind of information technology that provides virtual information for users through image, video, 3D model and other technologies while showing real scene, realizes the clever fusion of virtual information and real world. In many AR optical display schemes, the relief grating waveguide uses relief grating to replace traditional catadioptric optical device as the in-coupling, out-coupling and exit pupil expander in the optical waveguide scheme, and is considered as the most promising implementation scheme of consumer-level AR glasses due to its excellent performance.
[0003] However, the existing optical waveguide lens has the problem of uneven image brightness, which also leads to low display efficiency of AR glasses. UTILITY MODEL CONTENT
[0004] To solve the problems in the prior art, one of the purposes of the utility model is to provide a diffractive optical waveguide.
[0005] The utility model provides the following technical scheme:
[0006] A diffractive optical waveguide comprises a substrate layer and a grating layer arranged in layers.
[0007] The grating layer comprises an entrance light area, an anti-reflection area and an exit light area, which are arranged in the first direction.
[0008] At least two groups of first gratings are arranged in the exit light area, and the height of at least two groups of first gratings increases along the first direction.
[0009] As a further optional scheme of the diffractive optical waveguide, the width of each group of first gratings along the first direction is T, and 200nm≤T≤700nm.
[0010] The height difference between adjacent two groups of first gratings is ΔH, and 30nm≤ΔH≤100nm.
[0011] As a further optional scheme of the diffractive optical waveguide, the anti-reflection area is provided with a second grating, the second grating comprises a plurality of first grating teeth and a plurality of second grating teeth, the plurality of first grating teeth and the plurality of second grating teeth are arranged alternately along the first direction, and the height of the first grating teeth is less than the height of the second grating teeth.
[0012] As a further optional scheme of the diffraction optical waveguide, a third grating is arranged in the light inlet area, and the diffraction optical waveguide further comprises a reflective layer, which is arranged on a side of the third grating away from the substrate layer.
[0013] As a further optional scheme of the diffraction optical waveguide, a third grating is arranged in the light inlet area, and the diffraction optical waveguide further comprises a reflective layer, which is arranged on a side of the third grating away from the substrate layer.
[0014] As a further optional scheme of the diffraction optical waveguide, the diffraction optical waveguide further comprises an antireflection layer, which is arranged on a side of the substrate layer away from the grating layer, and the area covered by the antireflection layer corresponds to the light inlet area.
[0015] As a further optional scheme of the diffraction optical waveguide, the diffraction optical waveguide further comprises a waveguide substrate layer, which is arranged between the substrate layer and the grating layer, and the refractive index of the waveguide substrate layer is greater than that of the substrate layer.
[0016] As a further optional scheme of the diffraction optical waveguide, the waveguide substrate layer is a silicon carbide layer, and the refractive index of the silicon carbide layer is n1, n1≥2.7.
[0017] As a further optional scheme of the diffraction optical waveguide, the thickness of the waveguide substrate layer is less than that of the substrate layer.
[0018] Another object of the present application is to provide a display device.
[0019] The present application provides the following technical solutions:
[0020] A display device comprises the diffraction optical waveguide.
[0021] The embodiments of the present application have the following advantages:
[0022] When the diffraction optical waveguide works, a light beam is incident from a side of the substrate layer away from the grating layer and corresponding to the light inlet area, then undergoes total reflection in the substrate layer, and is transmitted to a region corresponding to the antireflection area and a region corresponding to the light outlet area in sequence, and finally is emitted from a side of the substrate layer away from the grating layer and corresponding to the light outlet area. In this process, the at least two groups of first gratings arranged in the light outlet area in the propagation direction of the light beam have increasing heights, so that the coupling output diffraction efficiencies of the groups of first gratings are different. Thus, the energy step-by-step output of the first gratings realizes the characteristic of pupil expansion, and the luminous flux output per unit area in the effective area remains constant, so that the presented image brightness is more uniform. On this basis, the display efficiency of the display device comprising the diffraction optical waveguide is improved.
[0023] In order to make the above objects, features and advantages of the present application more obvious and easy to understand, the following preferred embodiments are described in detail, and the accompanying drawings are described as follows. BRIEF DESCRIPTION OF DRAWINGS
[0024] In order to make the above objects, features and advantages of the present application more obvious and easy to understand, the following preferred embodiments are described in detail, and the accompanying drawings are described as follows.
[0025] Figure 1 The overall structure of the diffraction optical waveguide is shown in the schematic diagram of the embodiment of the present application.
[0026] Figure 2 The structure of the light-out area in the diffraction optical waveguide is shown in the schematic diagram of the embodiment of the present application.
[0027] Figure 3 The structure of the light-out area in the diffraction optical waveguide is shown in the schematic diagram of the embodiment of the present application.
[0028] Figure 4 The structure of the light-out area in the diffraction optical waveguide is shown in the schematic diagram of the embodiment of the present application.
[0029] Main element symbol explanation:
[0030] 100-substrate layer; 200-grating layer; 210-light-in area; 220-anti-reflection area; 230-light-out area; 240-first grating; 250-second grating; 251-first grating tooth; 252-second grating tooth; 260-third grating; 270-viscous transition layer; 300-waveguide base layer; 400-anti-reflection layer; 500-reflective layer. DETAILED DESCRIPTION
[0031] The embodiments of the present application are described in detail below, and the examples of the embodiments are shown in the accompanying drawings, wherein the same or similar reference signs represent the same or similar elements or elements with the same or similar functions throughout. The embodiments described below by referring to the accompanying drawings are exemplary and are only used to explain the present application, and cannot be understood as limiting the present application.
[0032] It should be noted that when an element is referred to as being "on" another element, it can be directly on the other element or intervening elements can also be present. In contrast, when an element is referred to as being "directly on" another element, there are no intervening elements present. Like terms are used to describe like elements in the figures and the description.
[0033] In the present application, unless otherwise explicitly specified and limited, the terms "mounting", "connecting", "connecting", "fixing" and the like should be understood in a broad sense, for example, it can be fixedly connected, or it can be detachably connected, or it can be integrated; it can be mechanically connected, or it can be electrically connected; it can be directly connected, or it can be indirectly connected through an intermediate medium; it can be the internal communication of two elements or the interaction relationship between two elements. For those skilled in the art, the specific meaning of the above terms in the present application can be understood according to the specific circumstances.
[0034] In addition, the terms "first", "second" are only for descriptive purposes, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of indicated technical features. Therefore, the features defined as "first", "second" can explicitly or implicitly include one or more features. In the description of the present application, the meaning of "multiple" is two or more, unless otherwise explicitly specified and limited.
[0035] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. The terms used in the specification of the template are only for the purpose of describing the specific embodiments, and are not intended to limit the present application. The term "and / or" used herein includes any and all combinations of one or more related listed items.
[0036] The present application discloses a kind of optical waveguide glasses, including glass cover sheet, grating structure and optical waveguide sheet, glass cover sheet is arranged on grating structure, grating structure is arranged on optical waveguide sheet.The present application discloses a kind of optical waveguide glasses, including glass cover sheet, grating structure and optical waveguide sheet, glass cover sheet is arranged on grating structure, grating structure is arranged on optical waveguide sheet.The present application discloses a kind of optical waveguide glasses, including glass cover sheet, grating structure and optical waveguide sheet, glass cover sheet is arranged on grating structure, grating structure is arranged on optical waveguide sheet.
[0037] Meanwhile, the refractive index of the current high-refraction glass reaches a bottleneck, and there are problems such as stray light caused by secondary coupling-out of high-refraction, which is very limited for improving the optical performance of the AR glasses. Therefore, how to provide a new type of optical waveguide sheet, which has the advantages of high-refraction, large field of view, reducing rainbow stripes, and realizing single-piece full-color image and avoiding stray light caused by secondary coupling-out, is a problem to be solved at present.
[0038] To solve the above problems, the embodiment provides a diffractive optical waveguide, in particular, a diffractive optical waveguide structure applied to AR / VR (Virtual Reality). Figure 1 and Figure 2 The diffractive optical waveguide comprises a substrate layer 100 and a grating layer 200 arranged in layers.
[0039] The grating layer 200 comprises an entrance light area 210, an anti-reflection area 220 and an exit light area 230, and the entrance light area 210, the anti-reflection area 220 and the exit light area 230 are arranged in sequence along a first direction.
[0040] Among them, at least two groups of first gratings 240 are arranged in the exit light area 230. The at least two groups of first gratings 240 are arranged along the first direction, and the height of the at least two groups of first gratings 240 increases along the first direction.
[0041] When the above diffractive optical waveguide works, a light beam is incident from the side of the substrate layer 100 away from the grating layer 200 and corresponding to the entrance light area 210, then totally reflects in the substrate layer 100, propagates to the region corresponding to the anti-reflection area 220 and the region corresponding to the exit light area 230 in sequence, and finally exits from the side of the substrate layer 100 away from the grating layer 200 and corresponding to the exit light area 230. In this process, the height of the at least two groups of first gratings 240 arranged in the exit light area 230 along the propagation direction of the light beam increases, so that the coupling output diffraction efficiency of each group of first gratings 240 is different. Thus, according to the step-by-step output of the energy of the first grating 240, the exit pupil expansion characteristic is realized, and the light flux output per unit area in the effective area remains constant, so that the brightness of the presented image is more uniform. On this basis, the display efficiency of the display device comprising the above diffractive optical waveguide is improved.
[0042] Specifically, the first direction is perpendicular to the normal direction of the substrate layer 100 and the grating layer 200, and is shown as the X direction in the figure.
[0043] In addition, the light beam propagates from the region corresponding to the entrance light area 210 to the region corresponding to the exit light area 230, and passes through the region corresponding to the anti-reflection area 220 in the middle. In the above diffractive optical waveguide, the propagation direction of the light beam is parallel to the first direction.
[0044] Please refer to Figure 1In some embodiments, the diffractive optical waveguide further comprises a waveguide base layer 300. The waveguide base layer 300 is arranged between the substrate layer 100 and the grating layer 200, i.e., the substrate layer 100, the waveguide base layer 300 and the grating layer 200 are arranged in sequence. In addition, the refractive index of the waveguide base layer 300 is greater than the refractive index of the substrate layer 100.
[0045] After the light beam is incident from the side of the substrate layer 100 away from the grating layer 200, it passes through the substrate layer 100 and the waveguide base layer 300, is reflected at the interface between the waveguide base layer 300 and the grating layer 200, and is refracted at the interface between the waveguide base layer 300 and the substrate layer 100 to enter the substrate layer 100. Subsequently, the light beam is reflected at the interface between the substrate layer 100 and the air, and is refracted at the interface between the substrate layer 100 and the waveguide base layer 300 to re-enter the waveguide base layer 300. This process is repeated until the light beam propagates from the region corresponding to the light-in area 210 to the region corresponding to the light-out area 230.
[0046] During this process, the waveguide base layer 300 can increase the bending angle of the light beam propagating in the entire diffractive optical waveguide, ultimately increase the field of view angle, and reduce the range of external stray light affected by rainbow stripes.
[0047] Further, the waveguide base layer 300 is a silicon carbide layer, and the refractive index of the silicon carbide layer is n1, which satisfies n1≥2.7.
[0048] Correspondingly, the substrate layer 100 adopts a glass substrate, and the refractive index of the glass substrate is n2, which satisfies 1.5≤n2≤1.8.
[0049] In use, the silicon carbide layer can greatly increase the bending angle of the light beam, thereby better increasing the field of view angle and reducing the range of external stray light affected by rainbow stripes.
[0050] Further, the thickness of the waveguide base layer 300 is less than the thickness of the substrate layer 100.
[0051] Making the thickness of the waveguide base layer 300 less than the thickness of the substrate layer 100 is conducive to controlling the size of the entire diffractive optical waveguide in the thickness direction, avoiding that the diffractive optical waveguide is too thick and heavy.
[0052] For example, the thickness of the waveguide base layer 300 is H1, which satisfies 0.1mm≤H1≤0.15mm. In addition, the thickness of the substrate layer 100 is H2, which satisfies 0.4mm≤H2≤0.6mm.
[0053] Alternatively, the thickness of the waveguide base layer 300 can be 0.1mm, 0.11mm, 0.12mm, 0.13mm, 0.14mm, 0.15mm, or any value between 0.1mm and 0.15mm.
[0054] Optionally, the thickness of the substrate layer 100 can be 0.4 mm, 0.42 mm, 0.44 mm, 0.46 mm, 0.48 mm, 0.5 mm, 0.52 mm, 0.54 mm, 0.56 mm, 0.58 mm, 0.6 mm, or any value between 0.4 mm and 0.6 mm.
[0055] In some embodiments, the diffractive optical waveguide described above further comprises an antireflection layer 400. The antireflection layer 400 is disposed on the side of the substrate layer 100 away from the grating layer 200, and the area covered by the antireflection layer 400 corresponds to the light-in area 210.
[0056] In use, the antireflection layer 400 can reduce the reflection loss of the light beam on the surface of the substrate layer 100 when the light beam is incident on the substrate layer 100, thereby improving the optical efficiency.
[0057] For example, the antireflection layer 400 can be made of magnesium fluoride, titanium oxide, lead sulfide, lead selenide, ceramic infrared light antireflection film, and vinyl silsesquioxane hybrid film, and the refractive index of the antireflection layer 400 is generally between that of glass and air.
[0058] For example, the antireflection layer 400 can be made of magnesium fluoride, titanium oxide, lead sulfide, lead selenide, ceramic infrared light antireflection film, and vinyl silsesquioxane hybrid film, and the refractive index of the antireflection layer 400 is generally between that of glass and air. Figure 2 In some embodiments, the width of each group of first gratings 240 along the first direction is T, and 200 nm≤T≤700 nm.
[0059] At the same time, the height difference between two adjacent groups of first gratings 240 is ΔH, and 30 nm≤ΔH≤100 nm.
[0060] In this way, the light flux output per unit area in the effective area of the light-out area 230 is more stable, the image brightness is more uniform, and the display efficiency of the display device is maximized.
[0061] Optionally, the width of each group of first gratings 240 along the first direction can be 200 nm, 250 nm, 300 nm, 350 nm, 400 nm, 450 nm, 500 nm, 550 nm, 600 nm, 650 nm, 700 nm, or any value between 200 nm and 700 nm.
[0062] Optionally, the height difference between two adjacent groups of first gratings 240 can be 30 nm, 40 nm, 50 nm, 60 nm, 70 nm, 80 nm, 90 nm, 100 nm, or any value between 30 nm and 100 nm.
[0063] For example, the diameter, width, or length of the first grating 240 can be 50-650 nm, and the height or depth of the first grating 240 can be 80-650 nm.
[0064] For example, the antireflection layer 400 can be made of magnesium fluoride, titanium oxide, lead sulfide, lead selenide, ceramic infrared light antireflection film, and vinyl silsesquioxane hybrid film, and the refractive index of the antireflection layer 400 is generally between that of glass and air. Figure 3In some embodiments, a second grating 250 is provided within the anti-reflection region 220. The second grating 250 includes a plurality of first grating teeth 251 and a plurality of second grating teeth 252. The plurality of first grating teeth 251 and the plurality of second grating teeth 252 are arranged alternately along a first direction, and the height of the first grating teeth 251 is less than the height of the second grating teeth 252.
[0065] Understandably, the second grating 250 employs a highly staggered grating structure, which can more effectively capture and scatter light, improve light reflection efficiency, and reduce beam loss at the interface between the waveguide substrate layer 300 and the grating layer 200.
[0066] Please refer to the following: Figure 1 and Figure 4 In some embodiments, a third grating 260 is disposed within the light incident region 210, and the third grating 260 has an equal height. Accordingly, the above-mentioned diffractive waveguide also includes a reflective layer 500, and the reflective layer 500 is disposed on the side of the third grating 260 facing away from the substrate layer 100.
[0067] In use, the reflective layer 500 can enhance the reflection of the incident light region 210, thereby improving the light reflection efficiency and reducing the outgoing beam loss at the interface between the waveguide substrate layer 300 and the grating layer 200.
[0068] Furthermore, an adhesive transition layer 270 is also provided within the light-receiving area 210. The adhesive transition layer 270 wraps around the third grating 260, and the reflective layer 500 is connected to the adhesive transition layer 270.
[0069] Understandably, the adhesive transition layer 270 fills and wraps the third grating 260, which helps the reflective layer 500 to better adhere and fix, and makes the reflective layer 500 and the grating layer 200 stably connected.
[0070] When the aforementioned diffractive waveguide operates, the light beam is incident from the side of the substrate 100 away from the grating layer 200, corresponding to the incident light region 210. It then undergoes total internal reflection at the interface between the waveguide substrate 300 and the grating layer 200, and at the interface between the substrate 100 and air, propagating successively to the region corresponding to the anti-reflection region 220 and the region corresponding to the exit light region 230, finally exiting from the side of the substrate 100 away from the grating layer 200, corresponding to the exit light region 230. During this process, at least two sets of first gratings 240 arranged along the beam propagation direction within the exit light region 230 have progressively increasing heights, resulting in different coupling output diffraction efficiencies for each set of first gratings 240. Therefore, based on the characteristic of stepwise energy output from the first gratings 240 to achieve exit pupil expansion, the luminous flux output per unit area within the effective region remains constant, resulting in more uniform image brightness. Based on this, the display efficiency of the display device including the aforementioned diffractive waveguide is improved.
[0071] In addition, the antireflection layer 400, the reflection layer 500, the second grating 250 and the like can reduce light loss and improve optical efficiency.
[0072] The embodiment also provides a display device including the above diffractive optical waveguide.
[0073] Exemplarily, the display device can be AR glasses, VR glasses or the like.
[0074] In all examples shown and described herein, any specific values should be interpreted as merely exemplary and not limiting, and thus other examples of the exemplary embodiments can have different values.
[0075] It should be noted that similar reference numbers and letters refer to similar items in the following drawings, and thus, once an item is defined in one drawing, it need not be further defined and explained in subsequent drawings.
[0076] The above-described embodiments only express several implementation manners of the present application, and the description is relatively specific and detailed, but it should not be understood as a limitation on the scope of the present application. It should be pointed out that, for ordinary skilled in the art, without departing from the concept of the present application, a number of modifications and improvements can be made, which all belong to the protection scope of the present application.
Claims
1. A diffractive optical waveguide, characterized in that, Includes a substrate layer and a grating layer stacked together; The grating layer includes an incident light region, an anti-reflection region, and an exit light region, wherein the incident light region, the anti-reflection region, and the exit light region are arranged sequentially along a first direction; The light-emitting area is provided with at least two sets of first gratings, the at least two sets of first gratings are arranged along the first direction, and the height of the at least two sets of first gratings increases along the first direction.
2. The diffractive waveguide according to claim 1, characterized in that, The width of the first grating in each group along the first direction is T, where 200nm≤T≤700nm; The height difference between two adjacent sets of the first grating is ΔH, where 30nm≤ΔH≤100nm.
3. The diffractive waveguide according to claim 1, characterized in that, The antireflection zone is provided with a second grating, which includes a plurality of first grating teeth and a plurality of second grating teeth. The plurality of first grating teeth and the plurality of second grating teeth are arranged alternately along the first direction, and the height of the first grating teeth is less than the height of the second grating teeth.
4. The diffractive waveguide according to claim 1, characterized in that, A third grating is provided in the light incident area, and the diffractive waveguide also includes a reflective layer, which is covered on the side of the third grating away from the substrate layer.
5. The diffractive waveguide according to claim 4, characterized in that, An adhesive transition layer is also provided in the light incident area. The adhesive transition layer wraps around the third grating, and the reflective layer is connected to the adhesive transition layer.
6. The diffractive waveguide according to claim 1, characterized in that, The diffractive waveguide further includes an anti-reflection layer, which is disposed on the side of the substrate layer away from the grating layer, and the area covered by the anti-reflection layer corresponds to the incident light region.
7. The diffractive waveguide according to any one of claims 1-6, characterized in that, The diffractive waveguide further includes a waveguide substrate layer, which is disposed between the substrate layer and the grating layer, and the refractive index of the waveguide substrate layer is greater than that of the substrate layer.
8. The diffractive waveguide according to claim 7, characterized in that, The waveguide substrate is a silicon carbide layer with a refractive index of n1, where n1 ≥ 2.
7.
9. The diffractive waveguide according to claim 7, characterized in that, The thickness of the waveguide substrate layer is less than the thickness of the substrate layer.
10. A display device, characterized in that, Includes the diffractive waveguide according to any one of claims 1-9.