Optical waveguide and head-up display system

Abstract

The utility model relates to projection display technical field discloses a kind of light waveguide and head-up display system, light waveguide includes: light waveguide body;Coupling-out grating, located the surface of the light waveguide body;Coupling-in grating, located the surface of the light waveguide body, and the coupling-in grating is located the central position of the light waveguide body;Light uniformizing device, located the one side of the light waveguide body away from the coupling-in grating, and it is opposite to be arranged with the coupling-in grating, and the light uniformizing device is used for balancing the relative brightness of straight penetration light that is emitted by the coupling-in grating and the diffracted coupling-out light that is emitted by the coupling-out grating.The utility model is by setting light uniformizing device in the center of light waveguide body, the straight penetration light that is emitted by coupling-in grating is carried out light uniformizing processing, not only can improve the display efficiency of AR-HUD, and can homogenize the image brightness of central coupling-in waveguide output.

Description

Technical Field

[0001] This utility model relates to the field of projection display technology, and in particular to an optical waveguide and head-up display system. Background Technology

[0002] AR-HUD is a product of the fusion of Augmented Reality (AR) technology and HUD. To improve the display efficiency of AR-HUD, a centrally coupled waveguide design is proposed, where the coupling region of the centrally coupled waveguide is located within the coupling region, and the optical engine directly emits the image towards the center of the waveguide. Unlike AR glasses, AR-HUD users receive reflected images, so this placement of the optical engine does not obstruct the view. Compared to a normal diffractive waveguide architecture, in the centrally coupled waveguide, diffracted light rays from the coupling region in all directions can enter the coupling region, and light rays at all angles have shorter propagation paths before being coupled out. For all diffractive waveguides, a significant proportion of the light rays projected by the optical engine into the coupling region pass directly through the coupling region. In the HUD system, these directly transmitted rays are reflected before entering the user's eyes. Because the directly transmitted light does not undergo multiple diffractions in the waveguide, its brightness is much higher than the image light rays normally coupled out through the waveguide. If the HUD system were applied in a vehicle, this could pose a safety hazard to the driver.

[0003] To address this issue, existing solutions completely block the direct light transmission by setting up a blocking structure in the coupling region. However, since the coupling region of a centrally coupled waveguide architecture is located in the center of the waveguide, using a structure to block the direct light transmission will result in uneven image brightness.

[0004] Therefore, existing technologies still need to be improved and developed. Utility Model Content

[0005] In view of the shortcomings of the prior art, the purpose of this utility model is to provide an optical waveguide and head-up display system to solve the problem of uneven image brightness caused by the use of blocking structural components to block direct light transmission in the existing center-coupled waveguide architecture.

[0006] The technical solution of this utility model is as follows:

[0007] In a first aspect, this utility model provides an optical waveguide, comprising:

[0008] Optical waveguide body;

[0009] A coupling grating is located on the surface of the optical waveguide body;

[0010] A coupling grating is located on the surface of the optical waveguide body, and the coupling grating is located at the center of the optical waveguide body;

[0011] A light-diffusing device is located on the side of the optical waveguide body away from the coupling grating and is disposed opposite to the coupling grating. The light-diffusing device is used to balance the relative brightness of the direct transmitted light emitted through the coupling grating and the diffracted coupled light emitted through the coupling grating.

[0012] In a further embodiment of this invention, the area of ​​the light-diffusing device is equal to the area of ​​the region from which the light is directly transmitted out of the coupled grating.

[0013] In a further embodiment of this invention, the light-uniforming device includes at least one microstructure, the geometric parameter distribution and some optical properties of the microstructure having centrosymmetric characteristics; the optical properties include transmittance and reflectance; the geometric parameters include geometric dimension parameters in the X, Y, and Z dimensions of a three-dimensional coordinate system.

[0014] A further feature of this invention is that one or more of the aforementioned microstructures constitute a unit structure; the unit structure has a period, the period being less than half of the minimum wavelength of the optical-mechanical output light.

[0015] In a further embodiment of this invention, the transmittance or reflectance of the light-diffusing device is distributed in a gradually varying manner on the surface.

[0016] In a further embodiment of this invention, the transmittance or reflectance of the light-diffusing device varies within the range of 0.01-10%.

[0017] In a further embodiment of this invention, the light-diffusing device is rectangular or circular in shape.

[0018] In a further improvement of this invention, the edges of the rectangular light-diffusing device are arc-shaped.

[0019] In a further embodiment of this invention, the light-diffusing device is a device made of silicon, silicon oxide, titanium oxide, silicon nitride, or silicon carbide.

[0020] Secondly, this utility model also provides a head-up display system, which includes an optomechanical system and an optical waveguide as described above, wherein the coupling grating is located on the outgoing optical path of the optomechanical system.

[0021] This invention provides an optical waveguide and head-up display system. The optical waveguide includes: an optical waveguide body; an output grating located on the surface of the optical waveguide body; an input grating located on the surface of the optical waveguide body, with the input grating positioned at the center of the optical waveguide body; and a light-diffusing device located on the side of the optical waveguide body away from the input grating and opposite to the input grating. The light-diffusing device is used to balance the relative brightness of the direct light emitted through the input grating and the diffracted coupled light emitted through the output grating. By placing a light-diffusing device at the center of the optical waveguide body, this invention performs light-diffusing processing on the direct light emitted through the input grating, which not only improves the display efficiency of the AR-HUD but also homogenizes the image brightness output from the central input waveguide. Attached Figure Description

[0022] To more clearly illustrate the technical solutions in the embodiments of this utility model or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this utility model. For those skilled in the art, other drawings can be obtained based on the structures shown in these drawings without creative effort.

[0023] Figure 1 This is a diagram illustrating the working principle of AR-HUD applied to vehicles.

[0024] Figure 2 This is a schematic diagram of a large-format waveguide with a center-coupled architecture.

[0025] Figure 3 This is a schematic diagram illustrating the working principle of a center-coupled waveguide, a two-dimensional top-coupled waveguide, and a one-dimensional folded waveguide.

[0026] Figure 4 This is a schematic diagram illustrating the principle of using a blocking structure to block direct light transmission in a large-format waveguide structure with a centrally coupled architecture.

[0027] Figure 5 This is a diagram showing the output brightness distribution of an optical waveguide in a large-format waveguide structure with a centrally coupled architecture, where a blocking structure is used to block direct light transmission.

[0028] Figure 6 This is a schematic diagram of the optical waveguide structure in one embodiment of the present invention.

[0029] Figure 7 This is a schematic diagram of the microstructure of the light-diffusing device in this utility model.

[0030] Figure 8 This is a coordinate system definition diagram of the light-diffusing device in one embodiment of this utility model.

[0031] Figure 9 This is a distribution diagram of the surface morphology parameters of the light-diffusing device in one embodiment of this utility model.

[0032] Figure 10 This is a schematic diagram of the external design of the light-diffusing device in one embodiment of this utility model.

[0033] Figure 11 This is a cross-sectional view of the edge of the light-diffusing device in one embodiment of the present invention after bending treatment.

[0034] Figure 12 This is a schematic diagram of the structure of a rectangular optical waveguide as the light-monopolating device in one embodiment of the present invention.

[0035] Figure 13 This is a cross-sectional view of the light-diffusing device in one embodiment of the present invention.

[0036] Figure 14 This is a transmittance distribution diagram and an optical waveguide output image of a uniform light device in one embodiment of this utility model.

[0037] Figure 15 This is a schematic diagram of the structure of a circular optical waveguide as the light-monopolating device in one embodiment of the present invention.

[0038] Figure 16 This is a cross-sectional view of the light-diffusing device in another embodiment of the present invention.

[0039] Figure 17 This is a transmittance distribution diagram and an optical waveguide output image of the uniform light device in another embodiment of this utility model.

[0040] The following labels in the attached diagram are: 100, optical waveguide; 110, optical waveguide body; 120, coupling grating; 130, coupling grating; 140, homogenizing device; 150, coupling region; 160, coupling region; 200, optomechanical system; 300, windshield; 400, diffraction waveguide; 500, shielding structure. Detailed Implementation

[0041] This utility model provides an optical waveguide and head-up display system. To make the purpose, technical solution, and effects of this utility model clearer and more explicit, the following describes this utility model in further detail with reference to the accompanying drawings and examples. It should be understood that the specific embodiments described herein are merely illustrative of this utility model and are not intended to limit this utility model.

[0042] In the implementation methods and claims, unless otherwise specified in the text, the terms "a," "an," "the," and "the" may also include plural forms. If the embodiments of this utility model involve descriptions of "first," "second," etc., such descriptions are for descriptive purposes only and should not be construed as indicating or implying their relative importance or implicitly specifying the number of indicated technical features. Therefore, a feature defined with "first" or "second" may explicitly or implicitly include at least one of those features.

[0043] It should be further understood that the term "comprising" as used in this specification means the presence of the stated features, integers, steps, operations, elements, and / or components, but does not exclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and / or groups thereof. It should be understood that when an element is referred to as "connected" or "coupled" to another element, it can be directly connected or coupled to the other element, or there may be intermediate elements present. Furthermore, "connected" or "coupled" as used herein can include wireless connections or wireless coupling. The term "and / or" as used herein includes all or any of the units and all combinations thereof of one or more associatedly listed items.

[0044] It will be understood by those skilled in the art that, unless otherwise defined, all terms used herein (including technical and scientific terms) have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. It should also be understood that terms such as those defined in general dictionaries should be understood to have the same meaning as in the context of the prior art, and should not be interpreted in an idealized or overly formal sense unless specifically defined as herein.

[0045] Furthermore, the technical solutions of the various embodiments can be combined with each other, but this must be based on the ability of those skilled in the art to implement them. When the combination of technical solutions is contradictory or cannot be implemented, it should be considered that such combination of technical solutions does not exist and is not within the scope of protection claimed by this utility model.

[0046] The inventors discovered that AR-HUDs are typically used in vehicles, such as... Figure 1As shown, the image projected by the optomechanical system 200 is coupled out by the coupling region 160 of the diffraction waveguide 400 and then projected onto the windshield 300. After reflection from the windshield 300, it enters the driver's eyebox. Compared to waveguides in the form of eyeglasses, AR-HUD waveguides have a larger area and a longer eyeelief, thus the proportion of light energy received by the human eye in the total waveguide coupling energy is lower. Furthermore, in AR-HUDs, the image received by the user comes from the reflection of the waveguide-coupled image on the windshield. Generally, the reflectivity of the windshield 300 to natural light is only about 10%, making the display efficiency of the large-format waveguide in AR-HUDs much lower than its display efficiency in AR glasses. Since AR-HUDs are used outdoors, to ensure that users can observe clear and sufficiently bright images even in high-brightness ambient light, it is necessary to improve the display efficiency of AR-HUDs in various aspects while maintaining their display effect.

[0047] The center-coupled waveguide architecture is a waveguide design scheme proposed for large-format waveguides in AR-HUDs. The coupling region 150 of the center-coupled waveguide is located within the coupling region 160, and the optomechanical unit 200 transmits images directly towards the center of the waveguide, such as... Figure 2 As shown. Unlike AR glasses, AR-HUD users receive reflected images, so the placement of the optical engine 200 does not obstruct the view. Compared to a normal diffractive waveguide 400 architecture (such as...), Figure 3 As shown in a and b, where, Figure 3 In this context, 'b' represents a two-dimensional top-in waveguide. Figure 3 In this context, 'c' represents a one-dimensional folded waveguide, and center-coupled waveguides (such as...) Figure 3 As shown in a), diffracted rays from the coupling region 150 in all directions can enter the coupling region 160, and rays at each angle have a shorter propagation path before being coupled out.

[0048] Therefore, it is expected that the center-coupled architecture will have higher display efficiency. For all diffraction waveguides 400, a considerable proportion of the light projected from the optomechanical system 200 to the coupling region 150 will pass directly through the coupling region 150. In the HUD system, this directly transmitted light will be reflected off the windshield 300 and enter the driver's eyes. Since the directly transmitted light does not undergo multiple diffractions in the waveguide, its brightness is much higher than the image light normally coupled out of the waveguide, which may pose a safety hazard for the use of HUD during normal driving. To address this issue, a blocking structure 500 is usually used to completely block the directly transmitted light in the coupling region 150. However, a significant problem with the center-coupled waveguide architecture is that its coupling region 150 is located in the center of the waveguide. If the blocking structure 500 is used to block the directly transmitted light, it will inevitably block the light normally coupled out of the coupling region. This will cause the displayed image to be missing or result in extremely uneven image brightness, such as... Figure 4 and Figure 5 As shown.

[0049] To address the aforementioned technical problems, this invention provides an optical waveguide and head-up display system. By placing a light-uniforming device at the center of the optical waveguide body, the direct-transmitted light emitted from the coupled grating is uniformly processed. This not only improves the display efficiency of the AR-HUD but also homogenizes the image brightness output from the central coupled waveguide. Furthermore, the light-uniforming device can act on all direct-transmitted light incident on the eye-tracking range, while minimizing the area affected by the normally coupled light in the coupling area, thus avoiding obstruction of the normally coupled light and preventing image loss.

[0050] Please also refer to Figures 6 to 17 This utility model provides a preferred embodiment of an optical waveguide.

[0051] In some embodiments, such as Figure 6 As shown, this utility model provides an optical waveguide 100, which includes: an optical waveguide body 110, a coupling grating 130, a coupling grating 120, and a light homogenizing device 140. The coupling grating 130 is located on the surface of the optical waveguide body 110; the coupling grating 120 is located on the surface of the optical waveguide body 110, and the coupling grating 120 is located at the center of the optical waveguide body 110; the light homogenizing device 140 is located on the side of the optical waveguide body 110 away from the coupling grating 120, and is disposed opposite to the coupling grating 120. The light homogenizing device 140 is used to balance the relative brightness of the direct transmitted light emitted through the coupling grating 120 and the diffracted coupled light emitted through the coupling grating 130.

[0052] In this embodiment, the optical waveguide 100 has an insertion region 150 and an exit region 160. The insertion grating 120 is located in the insertion region 150, and the exit grating 130 is located in the exit region 160. The insertion region 150 is located at the center of the optical waveguide body 110, and the optical engine 200 emits image light directly towards the center of the optical waveguide body 110. Since the AR-HUD user receives a reflected image, the optical engine 200 is positioned in this way without obstructing the view. Compared to the normal diffraction waveguide 400 architecture, the diffracted light rays from the insertion region 150 of the central insertion waveguide can enter the exit region 160 in all directions, and the light rays at each angle have a shorter propagation path before being coupled out, thereby achieving higher display efficiency. Even in outdoor scenes, users can observe clear and sufficiently bright images in high-brightness ambient light, ensuring display quality.

[0053] A significant proportion of the light projected from the optical engine 200 to the coupling region 150 passes directly through the coupling region 150. This directly transmitted light does not undergo multiple diffractions within the optical waveguide body 110, resulting in a brightness far exceeding that of the normally emitted image light from the optical waveguide body 110. This directly transmitted light, reflected into the user's eyes, may cause discomfort or safety hazards. For example, if an AR-HUD is used in a vehicle, this directly transmitted light will reflect off the windshield and enter the driver's eye, posing a safety hazard while driving. To address this, this embodiment uses a homogenizing device 140 at the center of the optical waveguide body 110 to homogenize the directly transmitted light emitted from the coupling grating 120, attenuating the brightness of the directly transmitted light projected by the optical engine 200 to a level close to the brightness of the normally emitted image light from the optical waveguide body 110.

[0054] In the above technical solution, the coupling grating 120 is positioned at the center of the optical waveguide 100. Diffracted light rays from the coupling region 150 of the central coupling waveguide can enter the coupling region 160 in all directions, and the light rays at each angle have shorter propagation paths before being coupled out, thereby achieving higher display efficiency. Furthermore, a homogenizing device 140 is further positioned at the center of the optical waveguide body 110 to homogenize the direct-transmitted light emitted from the coupling grating 120, attenuating the brightness of the direct-transmitted light projected by the optomechanical unit 200 to a level close to the brightness of the image light normally coupled out of the optical waveguide body 110. This not only improves the display efficiency of the AR-HUD but also homogenizes the image brightness output from the central coupling waveguide.

[0055] In some embodiments, such as Figure 7As shown, the light-uniforming device 140 includes at least one microstructure, the geometric parameter distribution and some optical properties of the microstructure have centrosymmetric characteristics; the optical properties include transmittance and reflectance; the geometric parameters include geometric dimension parameters in the three dimensions of X, Y and Z in a three-dimensional coordinate system.

[0056] In this embodiment, the parameter distribution of the homogenizing device 140 is rotationally symmetric to its optical properties, and its parameter distribution is optimizable. The optimization method typically involves using a surface expression with variable coefficients to define its distribution pattern. A surface expression with rotational symmetry is... Figure 8 The polar coordinate system shown has the following properties: in It can be any number between 0 and 2π, meaning to rotate this surface around the origin. At the angle of rotation, the surface morphology of the thickness curve is completely identical to that of the surface before rotation. There are countless surfaces that satisfy this condition; for example, the Zernike polynomial, commonly used in optical design, can be used to construct surfaces with central rotational symmetry. The surface expression is as follows:

[0057]

[0058] In the expression, A represents the surface coefficient. Changing the value of the surface coefficient A alters the surface morphology. For surfaces with central rotational symmetry, its value can increase, decrease, increase first and then decrease, or decrease first and then increase along any radial direction. Some surface morphology distributions with central rotational symmetry include... Figure 9 As shown. Regardless of the polynomial or polynomial coefficients used to define the expression of the surface, these surfaces ultimately need to satisfy the following relationship in polar coordinates: This ensures the rotational symmetry of the center.

[0059] The shape of the microstructure can be as follows: Figure 7 As shown, the microstructure has geometric dimensional parameters in three dimensions: X, Y, and Z. These parameters are variable and can be optimized. The microstructure includes cylindrical microstructures, hollow cylindrical microstructures, cuboid microstructures, and other microstructures with three-dimensional dimensional parameters. Different microstructures have different dimensional parameters. For example, when the microstructure is cylindrical, it has two geometric dimensional parameters: cylinder height and cylinder cross-sectional width.

[0060] The optical properties of the light-diffusing device 140 are determined by the geometric dimensions of the microstructure, and the optical properties and geometric dimensions have similar distribution characteristics. In this embodiment, the optical properties of the light-diffusing device 140 mainly refer to the transmittance or reflectance of the device. By optimizing the geometric dimensions of the microstructure, the distribution of transmittance and reflectance of the light-diffusing device on the entire device surface can be changed.

[0061] The homogenizing device 140 can operate in either transmission mode or reflection mode. In transmission mode, transmitted light emitted from the homogenizing device enters the human eye, while other light is reflected or absorbed. In reflection mode, reflected light emitted from the homogenizing device enters the human eye, while other light is transmitted or absorbed. Typically, in a center-coupled waveguide, the homogenizing device operates in transmission mode.

[0062] In some embodiments, the transmittance or reflectance of the homogenizing device 140 is gradually distributed on its surface; that is, the transmittance and reflectance of incident light differ at different spatial locations (i.e., different positions and different angles) on the homogenizing device. In some embodiments, the range of transmittance or reflectance of the homogenizing device is between 0.01% and 10%, for example, it can be 0.01%, 5%, or 10%.

[0063] In some embodiments, one or more of the microstructures constitute a unit structure; the unit structure has a period, the period being less than half of the minimum wavelength of the optical-mechanical output light.

[0064] In this embodiment, the homogenizing device 140 may or may not be periodic. A period P may contain one or more different microstructures, which together form a unit structure. The period P refers to the distance between adjacent unit structures, i.e., the period length. The distance between adjacent unit structures can be based on the distance between their geometric centers. In Figure 7, each unit structure contains only one microstructure. When the unit structure is periodic, all unit structures have the same period P. When the homogenizing device is non-periodic, different unit structures have different periods P. When the homogenizing device is periodic, the period is less than half the shortest wavelength of the emitted image light from the optomechanical system.

[0065] In some embodiments, the light-diffusing device 140 is a device made of silicon, silicon oxide, titanium oxide, silicon nitride, or silicon carbide. For example, in this embodiment, the light-diffusing device is a device made of silicon.

[0066] In some embodiments, such as Figure 10As shown, the area of ​​the light-diffusing device 140 is equal to the area of ​​the region from which the light is directly transmitted out of the coupling grating 120.

[0067] In this embodiment, if the size of the homogenizing device 140 is too large, it will affect the normal outgoing light in a larger area, resulting in a poorer homogenizing effect. If the size of the homogenizing device 140 is too small, it will be unable to block high-brightness direct-transmitted light that may harm the human eye. Therefore, the homogenizing device has a minimum size that satisfies the condition of being able to act on all direct-transmitted light incident on the eye movement range, but having the smallest area of ​​effect on the light normally outgoing from the outgoing region 160. In other words, the area of ​​the homogenizing device 140 is equal to the area of ​​the direct-transmitted light emitted from the coupling grating into the eye movement range. This maximizes the balance between the brightness of the direct-transmitted light from the optical engine and the brightness of the image normally outgoing from the optical waveguide.

[0068] The shape of the homogenizing device 140 is related to the field of view (FOV) projected by the optomechanical system 200, the distance d between the optomechanical system 200 and the optical waveguide 100, the distance between the human eye and the waveguide plane (Eyerelief) during observation, and the permissible eye movement range (Eyebox). Assuming the eye movement range is within... Figure 10 The dimension in the x-direction is L1, the eyelid distance (Eyerelief) is L2, the geometric center of the projection of the eye movement range onto the waveguide plane coincides with the geometric center of the waveguide, and the angle of the outermost ray of the optomechanical exit FOV in the x-direction is θ. Then the minimum dimension L in the x-direction of the homogenizing device satisfies:

[0069]

[0070] When the above conditions are met, all angles of direct light emitted from the optical engine 200 will not enter the range observable by the human eye, and the area of ​​the homogenizing device 140 that affects the normally coupled light rays will be minimized. The above description illustrates the minimum size of the homogenizing device in the x-direction. The calculation principle for its minimum size in the y-direction or other directions is the same as that in the x-direction, and will not be repeated here.

[0071] In some embodiments, the light-diffusing device 140 is rectangular or circular in shape.

[0072] Specifically, since the field of view (FOV) emitted by the optical engine 200 is usually rectangular and the exit pupil is usually circular, the shape of the homogenizing device 140 can be rectangular or circular.

[0073] In some embodiments, the optimal shape of the light-diffusing device 140 is a rectangle with curved edges, that is, the rectangular light-diffusing device 140 has arc-shaped edges, such as... Figure 11As shown. It should be noted that the final shape and size of the light-diffusing device 140 do not necessarily have to be the optimal shape described above; it can be larger or smaller than the optimal shape.

[0074] For example, such as Figure 12 and Figure 13 As shown, in this embodiment, the optical engine 200 has an emission FOV of 14° and a distance of 8 mm from the waveguide. The distance between the human eye and the optical waveguide is 750 mm. Based on the requirements for the homogenizing device 140 in the principle section, the homogenizing device 140 is set to a 21 mm * 21 mm rectangle. Its transmittance distribution is as follows... Figure 14 As shown in 'a', the values ​​in the figure represent the ratio of transmitted energy to incident energy after light enters this position. Figure 14 In the figure, 'b' represents the difference in brightness distribution between the simulated result and the actual brightness distribution when the human eye observes the waveguide output image from the position shown in the figure. Figure 5 The result of completely blocking the light transmission of the central waveguide is significantly improved, and correspondingly, the text display effect of the output image of the optical waveguide will also be improved.

[0075] For example, such as Figure 15 and Figure 16 As shown. With Figure 12 The difference in the embodiment is that the human eye observes the waveguide output image simultaneously with both eyes. The homogenizing device 140 is shaped as a circle with a diameter of 10.41 mm, and the transmittance distribution is as follows. Figure 17 As shown in a, at this point, the brightness distribution of the waveguide output image observed by the binoculars is also well homogenized, as shown in a diagram. Figure 17 As shown in b, compared to Figure 5 The effect of completely blocking the light transmission of the central waveguide is significantly improved, and correspondingly, the text display effect of the output image of the optical waveguide will also be improved.

[0076] In some embodiments, the present invention also provides a head-up display system, which includes an optomechanical system and an optical waveguide as described above, wherein the coupling grating is located in the outgoing optical path of the optomechanical system. Specific embodiments of the optical waveguide are described in detail here.

[0077] In summary, the optical waveguide and head-up display system provided by this utility model has the following beneficial effects:

[0078] By setting a light homogenizing device at the center of the optical waveguide body, the direct transmitted light emitted from the coupled grating is homogenized, which can not only improve the display efficiency of AR-HUD, but also homogenize the image brightness output from the central coupled waveguide.

[0079] The light-diffusing device can not only act on all direct light incident on the eye movement range, but also has the smallest effect area on the light normally coupled out of the coupling area, without blocking the light normally coupled out of the coupling area, thus avoiding the loss of displayed image.

[0080] It should be understood that the application of this utility model is not limited to the examples above. Those skilled in the art can make improvements or modifications based on the above description, and all such improvements and modifications should fall within the protection scope of the appended claims.

Claims

1. An optical waveguide, characterized in that, include: Optical waveguide body; A coupling grating is located on the surface of the optical waveguide body; A coupling grating is located on the surface of the optical waveguide body, and the coupling grating is located at the center of the optical waveguide body; A light-diffusing device is located on the side of the optical waveguide body away from the coupling grating and is disposed opposite to the coupling grating. The light-diffusing device is used to balance the relative brightness of the direct transmitted light emitted through the coupling grating and the diffracted coupled light emitted through the coupling grating.

2. The optical waveguide according to claim 1, characterized in that, The area of ​​the light-diffusing device is equal to the area of ​​the region from which the light is directly transmitted out of the coupled grating.

3. The optical waveguide according to claim 1, characterized in that, The light-uniform device includes at least one microstructure, the geometric parameter distribution and some optical properties of the microstructure having centrosymmetric characteristics; the optical properties include transmittance and reflectance; the geometric parameters include geometric dimension parameters in the X, Y and Z dimensions of a three-dimensional coordinate system.

4. The optical waveguide according to claim 3, characterized in that, One or more of the microstructures constitute a unit structure; the unit structure has a period, the period being less than half of the smallest wavelength of the outgoing light from the optomechanical system.

5. The optical waveguide according to claim 3, characterized in that, The transmittance or reflectance of the light-diffusing device exhibits a gradually varying distribution on its surface.

6. The optical waveguide according to claim 5, characterized in that, The transmittance or reflectance of the light-diffusing device varies within the range of 0.01-10%.

7. The optical waveguide according to claim 1, characterized in that, The light-diffusing device is rectangular or circular in shape.

8. The optical waveguide according to claim 7, characterized in that, The edges of the rectangular light-diffusing device are arc-shaped.

9. The optical waveguide according to claim 1, characterized in that, The light-diffusing device is made of silicon, silicon oxide, titanium oxide, silicon nitride, or silicon carbide.

10. A head-up display system, characterized in that, It includes an optomechanism and an optical waveguide as described in any one of claims 1-9, wherein the coupling grating is located in the outgoing optical path of the optomechanism.

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