Optical waveguide structure and display device

Abstract

The invention provides an optical waveguide structure and a display device, and relates to the technical field of optical waveguides, the optical waveguide structure comprises a waveguide sheet and a prism, the opposite side of the coupling-in surface of the waveguide sheet is provided with a first reflecting surface, the prism is located on the side, away from the first reflecting surface, of the coupling-in surface, and the incident surface of the prism and the first reflecting surface form an included angle relative to the coupling-in surface; light is vertically incident from the incident surface of the prism, passes through the prism, then sequentially passes through the coupling-in surface and the first reflecting surface of the waveguide sheet, and then is vertically emergent from the coupling-out surface through the second reflecting surface on the opposite side of the coupling-out surface of the waveguide sheet. Due to the fact that the first reflecting face of the waveguide sheet deflects, the prism also deflects, deflection of two dimensions is achieved, magnification rates of images in the horizontal direction and the vertical direction are the same, and image distortion cannot be caused. Meanwhile, the first reflecting surface and the prism deflect, so that the light reaches a large deflection angle, the pupil size is effectively increased, the thickness of the prism is reduced, and the overall size and weight of the optical waveguide structure are smaller.

Description

Technical Field

[0001] This application relates to the field of optical waveguide technology, specifically to an optical waveguide structure and a display device. Background Technology

[0002] In optical waveguide technology, since the outgoing light rays are often matched with the incoming light rays, and the outgoing light rays are mostly perpendicular to the outgoing light rays, the incoming light rays will also be perpendicular to the outgoing light rays. However, due to ergonomic considerations, when a person wears glasses, the angle between the optical engine (temple position) and the waveguide plate (lens position) often needs to be greater than 90°, generally 95° to 100° is preferable. Therefore, most designs use an additional prism to achieve this angle. The additional prism is placed outside the waveguide plate, after the exit pupil of the optical engine. This placement significantly increases the length of the optical engine and also affects the pupil matching between the optical engine and the waveguide plate. Summary of the Invention

[0003] The purpose of this application is to provide an optical waveguide structure and display device that can achieve a large deflection angle while effectively reducing the prism thickness, thereby reducing the system size and weight.

[0004] One aspect of this application provides an optical waveguide structure, including a waveguide sheet and a prism. A first reflecting surface is provided on the opposite side of the coupling surface of the waveguide sheet. The prism is located on the side of the coupling surface away from the first reflecting surface. The incident surface of the prism and the first reflecting surface both form an angle with respect to the coupling surface. Light is incident perpendicularly from the incident surface of the prism, passes through the prism, and then sequentially passes through the coupling surface of the waveguide sheet, the first reflecting surface, and then exits perpendicularly from the second reflecting surface on the opposite side of the output surface of the waveguide sheet.

[0005] Optionally, the first included angle between the first reflecting surface and the coupling surface is θ-α, and the second included angle between the incident surface of the prism and the coupling surface is β, satisfying 2α=β, θ=γ; γ is the third included angle between the output surface and the second reflecting surface.

[0006] Optionally, 0 < α ≤ 20°, 0 < β ≤ 20°.

[0007] Optionally, there is a gap between the exit surface of the prism and the coupling surface of the waveguide sheet.

[0008] Optionally, the exit surface of the prism is parallel to the coupling surface of the waveguide sheet.

[0009] Optionally, the coupling-in surface and the coupling-out surface are coplanar.

[0010] Optionally, the prism is made of the same material as the waveguide sheet.

[0011] Optionally, the prism includes a triangular prism.

[0012] Optionally, the pupil width w2 of the waveguide sheet satisfies: Where h1 is the thickness of the waveguide sheet, and the thickness is the maximum dimension of the coupling surface in the direction of the first reflecting surface.

[0013] In another aspect of this application, a display device is provided, comprising: an optical engine, and the aforementioned optical waveguide structure disposed on the light-emitting side of the optical engine.

[0014] The optical waveguide structure and display device provided in this application achieve two-dimensional deflection because the first reflecting surface of the waveguide sheet is deflected and the prism is also deflected. This ensures the image has the same magnification in both the horizontal and vertical directions, preventing image distortion. Simultaneously, the deflection of both the first reflecting surface and the prism effectively increases the pupil size and reduces the prism thickness while allowing the light to achieve a large deflection angle, resulting in a smaller overall size and weight of the optical waveguide structure. Attached Figure Description

[0015] To more clearly illustrate the technical solutions of the embodiments of this application, the accompanying drawings used in the embodiments of this application will be briefly introduced below. It should be understood that the following drawings only show some embodiments of this application and should not be regarded as a limitation of the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort.

[0016] Figure 1 This is a schematic diagram of an existing optical waveguide structure; Figure 2 This is one of the structural schematic diagrams of the optical waveguide structure provided in this embodiment; Figure 3 yes Figure 2 A comparative structural diagram; Figure 4 This is the second schematic diagram of the optical waveguide structure provided in this embodiment; Figure 5 yes Figure 3 A simplified model diagram; Figure 6 This is a simplified model diagram of the optical waveguide structure provided in this embodiment. Detailed Implementation

[0017] The technical solutions in the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings.

[0018] In the description of this application, it should be noted that the terms "inner" and "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, or the orientation or positional relationship commonly used when the product is in use. They are used only for the convenience of describing this application and for simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this application. Furthermore, the terms "first," "second," etc., are used only to distinguish descriptions and should not be construed as indicating or implying relative importance.

[0019] It should also be noted that, unless otherwise explicitly specified and limited, the terms "setup" and "connection" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this application based on the specific circumstances.

[0020] The patent application CN116184666A includes an optical system with a two-dimensional extended light-guiding optical element, and its patent appendix... Figure 4 A shows a waveguide for the right eye in the forward-facing direction, with the optical mechanism offset to the upper right rear of the wearer. This is a standard solution without any additional devices or modifications to the initial waveguide. The problem with this solution is that it does not meet ergonomic requirements. When the wearer wears the glasses, taking the right eye as an example, the right temple should be pointing directly backward. Considering the angle between the lens and the temple, the temple should be positioned slightly lower to the right rear relative to the lens. Since the optical mechanism should be aligned with the temple for easy concealment within the temple and a pleasing aesthetic design, the original design needs to be significantly shifted to the left and downward.

[0021] There are two solutions to this problem, and the patent provides one solution. (See attached patent appendix.) Figure 6 As shown in Figure D, by changing the angle of the waveguide coupling portion (region 16), the outgoing light beam is altered. Then, the entire waveguide is adjusted to meet the light direction requirements of the human eye. However, only a small horizontal angle adjustment is possible, failing to address the downward issue. Furthermore, it disrupts the original optical path relationship of the waveguide, resulting in chromatic aberration. This leads to more complex designs, a higher refractive index substrate requirement, and more difficult manufacturing processes.

[0022] Patent CN219625819U, concerning an oblique projection display optical engine and near-eye display glasses, proposes an oblique projection optical engine. Its purpose is to avoid the various problems mentioned in the aforementioned patents without altering the coupling optical path of the waveguide. This requires changing the angle between the optical engine's output ray and the optical engine body to satisfy the oblique intersecting angle between the waveguide and the optical engine. In other words, the output ray of the optical engine must meet the requirements of the waveguide, and then the main body of the optical engine is forcibly deflected towards the temple direction. This method is essentially achieved by adding an additional achromatic prism 120, as detailed in the patent appendix. Figure 2 The uniform light element 13 is shown.

[0023] This solution requires the addition of an achromatic prism. Whether this achromatic prism is incorporated into the waveguide or the optomechanical structure, it significantly increases the optical path length and alters the exit pupil position. The added prism needs to achromaticly correct, increasing the design complexity of the optomechanical system. To maintain the same pupil size, the optomechanical system is larger than that without a prism. However, prisms are generally made of two materials: low-dispersion and high-dispersion. Yet, chromatic aberration cannot be completely eliminated, inevitably introducing residual chromatic aberration, reducing the overall chromatic aberration effect, and increasing the overall complexity. Some designs can combine chromatic aberration with other optomechanical components, such as the PBS (Polymerized Optical Surface Mount), but this still doesn't fundamentally solve the problem. Most importantly, the prism deflects light in only one dimension, causing asymmetric image compression, such as different magnifications, leading to image distortion.

[0024] In view of this, to solve the above problems, this application provides an optical waveguide structure, please refer to... Figure 2 As shown, it includes a waveguide 110 and a prism 120. A first reflecting surface 112 is provided on the opposite side of the coupling surface 111 of the waveguide 110. The prism 120 is located on the side of the coupling surface 111 away from the first reflecting surface 112. The incident surface 121 and the first reflecting surface 112 of the prism 120 both form an angle with respect to the coupling surface 111. Light is perpendicularly incident from the incident surface 121 of the prism 120. After passing through the prism 120, it passes sequentially through the coupling surface 111 and the first reflecting surface 112 of the waveguide 110, and then exits perpendicularly from the second reflecting surface 113 on the opposite side of the coupling surface 114 of the waveguide 110.

[0025] Traditional typical waveguide 10 structure, such as Figure 1 As shown, light enters from the right side, is reflected by mirror 12, and enters waveguide 10. Due to TIR (total internal reflection), it propagates within waveguide 10, encounters multiple reflecting surfaces, and exits. Figure 1Only one detached reflector 13 is shown, and the subsequent optical path is omitted. In a conventional design, the incident and detached rays are perpendicular to the incident and detached surfaces 11 and 14, or the incident and detached rays have the same or opposite angles of incidence and emission. Otherwise, there will be chromatic aberration. Therefore, the tilt angle θ of the reflector 12 is equal to the angle γ of the detached reflector 13, i.e., γ = θ.

[0026] In this application, the first reflecting surface 112 of the coupled element is deflected, and a prism 120 is provided on the coupling surface 111 of the waveguide 110, so that the light rays are deflected synchronously, and the deflected light rays can enter and exit normally. The optical path is as follows: the light rays emitted by the optomechanical system first enter the prism 120 perpendicularly through the incident surface 121 of the prism 120, then exit through the exit surface 122 of the prism 120, and then enter through the coupling surface 111 of the waveguide 110. After being reflected by the first reflecting surface 112, the light rays are totally internalized in the waveguide 110. After encountering the second reflecting surface 113, the light rays are reflected towards the coupling surface 114 and exit perpendicularly from the coupling surface 114.

[0027] The optical waveguide structure provided in this application embodiment achieves deflection in two dimensions due to the deflection of the first reflecting surface 112 of the waveguide sheet 110 and the prism 120. This ensures the same magnification in both the horizontal and vertical directions, preventing image distortion. Simultaneously, the deflection of both the first reflecting surface 112 and the prism 120 allows for a large deflection angle while effectively increasing the pupil size and reducing the thickness of the prism 120, resulting in a smaller overall size and weight of the optical waveguide structure.

[0028] The waveguide sheet 110 of this application can be applied to reflective waveguides, diffraction grating waveguide sheets, volume holographic waveguide sheets, etc.

[0029] Specifically, the first included angle between the first reflecting surface 112 and the coupling surface 111 is θ-α, and the second included angle between the incident surface 121 of the prism 120 and the coupling surface 111 is β, satisfying 2α=β, θ=γ; γ is the third included angle between the output surface 114 and the second reflecting surface 113.

[0030] Figure 2 Compared to the first reflecting surface 112 in the middle Figure 1 α was deflected, therefore Figure 2 The first included angle formed between the coupling surface 111 of the middle waveguide 110 and the first reflecting surface 112 is θ-α, and θ=γ.

[0031] The incident surface 121 of the prism 120 is also deflected relative to the coupling surface 111 of the waveguide 110, and the second included angle formed by the deflection is β, and 2α=β.

[0032] Furthermore, 0 < α ≤ 20° and 0 < β ≤ 20° are set. The human eye typically looks downwards, and this downward viewing angle is called the lower angle, which is generally 5° to 15°, or the second included angle β. The left and right viewing angles are generally 0.5°, and the waveguide is typically worn at a 2.5° angle to the right. Because the human head is round, conforming to ergonomics, the sum of 0.5° and 2.5° is 3°, which is α. Therefore, α and β are set between 0° and 20°. However, in existing technology, both of these angle values ​​are 0, which is not ergonomic and is aesthetically unappealing.

[0033] In this application, the prism 120 is made of the same material as the waveguide 110, thus avoiding the introduction of chromatic aberration. For example, the prism 120 may include a triangular prism 120. When the prism 120 and the waveguide 110 are made of the same material, the manufacturing process is simpler, and the overall system size is smaller and lighter. The deflection angle of the prism 120 is only half that of a conventional additional prism 120, thus simplifying the design and allowing for a smaller system size.

[0034] On the other hand, the exit surface 122 of the prism 120 of this application is parallel to the coupling surface 111 of the waveguide 110, and the coupling surface 111 and the exit surface 114 of the waveguide 110 are coplanar.

[0035] In this application, there is a gap between the exit surface 122 of the prism 120 and the coupling surface 111 of the waveguide 110. In other words, an air layer 130 is maintained between the exit surface 122 of the prism 120 and the coupling surface 111 of the waveguide 110. This arrangement does not disrupt the total internal reflection condition and does not affect the size of the coupled light. If the prism 120 is in close contact with the coupling surface 111 of the waveguide 110, the total internal reflection condition will be disrupted, the cutoff edge of the waveguide 110 will shift to the left, and the amount of light that can pass through will decrease.

[0036] Specifically, assuming that the exit surface 122 of the prism 120 and the coupling surface 111 of the waveguide 110 are in contact, such as Figure 3 As shown, light is simultaneously blocked by P1 and P2, and the width of the light passing through is d. This application separates the prism 120 from the waveguide 110, leaving an air layer 130 between them, allowing light coupled into the air layer 130 to continue undergoing total internal reflection, as... Figure 4 As shown, this eliminates the cutoff point P2, causing the left-side light ray to be cut off by P1, thus greatly increasing the width d' of the light ray. Figure 4 The diagram demonstrates the pupil width of a 0° incident light beam. In reality, the cutoff will vary slightly depending on the incident light beam, and the beam width will often be smaller due to different incident angles.

[0037] exist Figure 5In the simplified model of Figure 6, the right boundary of the optical path of the two waveguide sheets 110 is the same, while the left optical path is different, which is represented by light black. The analysis of the pupil widths w1 and w2 of the coupling surface 111 is as follows: (1); (2); (3); (4); Substituting formulas (1), (2), and (3) into formula (4) yields: (5); Formula (6) is derived from formula (5): (6); Formula (7) is derived from formula (6): (7); Then according to Figure 6 It can be seen that the incident angle of the constructed ray is 2α: (8); From formula (8), we obtain formula (9). The pupil width w2 of the waveguide 110 in this application satisfies: (9); And according to Figure 5 , Figure 6 : ; ; Therefore: the pupil width w2 of the waveguide 110 in this application is compared to Figure 3 The pupil width w1 of waveguide 110 is increased, and the pupil width w is increased. d : ; ; ; ; Assume waveguide 110 has a thickness h1 = 1.5 mm, θ = 25.6°, α = 5°, and β = 10°; Substituting into the above formula, we get: w1 = 3.4664 mm; w2 = 1.6337 mm; w d =1.8327mm; Therefore, the waveguide 110 of this application is compared to Figure 3The waveguide 110 increases the pupil width by a significant percentage: w d / w2=112.2%.

[0038] In other words, compared to Figure 3 Prism 120 and waveguide 110 are fitted together. When an air layer 130 is maintained between prism 120 and waveguide 110, the aperture width of waveguide 110 is wider, allowing more light to pass through. More light passing through waveguide 110 makes the displayed image or information brighter, especially clearer in strong outdoor light conditions; more light passing through waveguide 110 also results in high light transmittance, allowing virtual information to blend more naturally with the real-world scene; it also improves light utilization efficiency, reduces energy loss, and thus lowers device power consumption; furthermore, it reduces image distortion, improving color accuracy and visual comfort.

[0039] Based on this, the present application also discloses a display device, including an optomechanism and an optical waveguide structure as described above disposed on the light-emitting side of the optomechanism.

[0040] This display device includes the same structure and beneficial effects as the optical waveguide structure in the foregoing embodiments. The structure and beneficial effects of the optical waveguide structure have been described in detail in the foregoing embodiments and will not be repeated here.

[0041] The above description is merely an embodiment of this application and is not intended to limit the scope of protection of this application. Various modifications and variations can be made to this application by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this application should be included within the scope of protection of this application.

Claims

1. An optical waveguide structure, characterized in that, include: A waveguide and a prism are provided. A first reflecting surface is provided on the opposite side of the coupling surface of the waveguide. The prism is located on the side of the coupling surface away from the first reflecting surface. The incident surface of the prism and the first reflecting surface both form an angle with respect to the coupling surface. Light is incident perpendicularly from the incident surface of the prism, passes through the prism, and then passes sequentially through the coupling surface of the waveguide, the first reflecting surface, and then exits perpendicularly from the second reflecting surface on the opposite side of the output surface of the waveguide.

2. The optical waveguide structure according to claim 1, characterized in that, The first included angle between the first reflecting surface and the coupling surface is θ-α, and the second included angle between the incident surface of the prism and the coupling surface is β, satisfying 2α=β, θ=γ; γ is the third included angle between the output surface and the second reflecting surface.

3. The optical waveguide structure according to claim 2, characterized in that, 0＜α≤20°，0＜β≤20°。 4. The optical waveguide structure according to any one of claims 1 to 3, characterized in that, There is a gap between the exit surface of the prism and the coupling surface of the waveguide plate.

5. The optical waveguide structure according to any one of claims 1 to 3, characterized in that, The exit surface of the prism is parallel to the coupling surface of the waveguide plate.

6. The optical waveguide structure according to any one of claims 1 to 3, characterized in that, The coupling-in surface and the coupling-out surface are coplanar.

7. The optical waveguide structure according to any one of claims 1 to 3, characterized in that, The prism is made of the same material as the waveguide sheet.

8. The optical waveguide structure according to any one of claims 1 to 3, characterized in that, The prism includes a triangular prism.

9. The optical waveguide structure according to any one of claims 2 to 3, characterized in that, The pupil width w2 of the waveguide sheet satisfies: Where h1 is the thickness of the waveguide sheet, and the thickness is the maximum dimension of the coupling surface in the direction of the first reflecting surface.

10. A display device, characterized in that, It includes an optical engine and an optical waveguide structure as described in any one of claims 1 to 9 disposed on the light-emitting side of the optical engine.

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