Optical waveguide, display device and head-up display system
By setting non-overlapping bright strip areas on each waveguide layer of the optical waveguide, the problem of poor brightness uniformity of the existing centrally coupled waveguide is solved, and an efficient and uniform display effect is achieved.
Patent Information
- Application Number
- CN202323546787.5
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- Filing Date
- 2023-12-25
- Publication Date
- 2025-03-11
- Estimated Expiration
- 2033-12-25
AI Technical Summary
The existing centrally coupled incoming waveguides have the problem of poor brightness uniformity of the exit image, which leads to some areas being particularly bright while others being relatively dark, affecting the final display effect.
An optical waveguide is designed, including at least two waveguide layers, each of which has a coupling in area and an outgoing area, with a plurality of non-overlapping bright strip regions on the coupling area. When light rays propagate from the coupling area to the coupling area, the brightness of the light emitted from the bright strip area is higher than that of other areas, and the uniformity of image brightness is achieved through the complementary bright strip area of multiple waveguide layers.
By setting non-overlapping bright strip areas, the light emitted from different waveguide layers is avoided from being superimposed at the same position, which significantly improves the brightness uniformity of the optical waveguide and achieves a display effect with high display efficiency and high uniformity.
Smart Images
Figure CN222599952U_ABST
Abstract
Description
Technical Field
[0001] The present application relates to the field of optical imaging technology, and more specifically, to an optical waveguide, a display device, and a head-up display system. Background Art
[0002] At present, the center-coupled waveguide generally refers to a large-format waveguide architecture in which the coupling area is located in the out-coupling area. This structure allows incident light from all directions in the coupling area to enter the out-coupling area, and the light has a shorter propagation path before it propagates from the coupling area to the out-coupling area and is coupled out, and the display efficiency is higher. Therefore, the center-coupled waveguide is being widely used.
[0003] However, the existing center-coupled waveguide has the problem of poor brightness uniformity of the output image. Some areas of the output image are particularly bright, while other areas are relatively dark. The brightness difference between the two is obvious, which affects the final display effect. Utility Model Content
[0004] The present application proposes an optical waveguide, a display device and a head-up display system to improve the above-mentioned defects.
[0005] In a first aspect, an embodiment of the present application provides an optical waveguide, comprising: at least two waveguide layers, wherein a plurality of the waveguide layers are stacked, each of the waveguide layers comprises an incoupling region and an outcoupling region, the incoupling region or a projection of the incoupling region toward the outcoupling region is located in the outcoupling region of the corresponding waveguide layer, the outcoupling region of each waveguide layer has a plurality of bright stripe regions, when light is coupled into the waveguide layer from the incoupling region and propagates to the outcoupling region for emission, the brightness of light emitted from the bright stripe region of the outcoupling region is higher than the brightness of light emitted from other regions of the outcoupling region except the bright stripe region; wherein the bright stripe regions on different waveguide layers do not overlap.
[0006] Optionally, the bright stripe regions on different waveguide layers complement each other, so that the brightness of the first image light formed by the light incident on the optical waveguide after propagating through the multiple waveguide layers is uniform.
[0007] Optionally, in each of the waveguide layers, when light propagates from the coupling-in region to the coupling-out region of the waveguide layer, it has multiple initial propagation directions, and one of the bright stripe regions corresponds to one of the initial propagation directions; wherein the multiple initial propagation directions of different waveguide layers are different.
[0008] Optionally, the optical waveguide includes a first waveguide layer and a second waveguide layer, the first waveguide layer has a first coupling-in region and a first coupling-out region, the second waveguide layer has a second coupling-in region and a second coupling-out region, the first coupling-out region is arranged around the first coupling-in region, and the second coupling-out region is arranged around the second coupling-in region; when light propagates from the coupling-in region of the first waveguide layer to the coupling-out region, it has a plurality of first initial propagation directions, the first coupling-out region has a plurality of first bright strip regions, and the distribution of each of the first bright strip regions on the first coupling-out region corresponds to one of the first initial propagation directions; when light propagates from the coupling-in region of the second waveguide layer to the coupling-out region, it has a plurality of second initial propagation directions, the second coupling-out region has a plurality of second bright strip regions, and the distribution of each of the second bright strip regions on the second coupling-out region corresponds to one of the second initial propagation directions.
[0009] Optionally, the width and divergence angle of the first bright stripe area are both variable, and the width and divergence angle of the second bright stripe area are both variable, wherein the divergence angle of the first bright stripe area refers to the angle of one end of the first bright stripe area close to the first coupling area, and the divergence angle of the second bright stripe area refers to the angle of one end of the second bright stripe area close to the second coupling area.
[0010] Optionally, the first coupling-in region and the first coupling-out region are two-dimensional gratings, and the second coupling-in region and the second coupling-out region are also two-dimensional gratings; the grating vector direction of the grating unit on the first coupling-in region differs from the grating vector direction of the grating unit on the second coupling-in region by 90° clockwise or counterclockwise, the grating vector direction of the grating unit on the first coupling-out region is opposite to the grating vector direction of the first coupling-in region, and the grating vector direction of the grating unit on the second coupling-out region is opposite to the grating vector direction of the second coupling-in region.
[0011] Optionally, the first coupling-in region and the second coupling-in region are one-dimensional gratings, and the first coupling-out region and the second coupling-out region are two-dimensional gratings, the grating vector direction of the grating unit on the first coupling-in region differs from the grating vector direction of the grating unit on the second coupling-in region by 90° clockwise or counterclockwise, and the grating vector direction of the grating unit on the first coupling-out region differs from the grating vector direction of the grating unit on the second coupling-out region by 90° clockwise or counterclockwise.
[0012] Optionally, the diffraction efficiency of the first waveguide layer for light with a first polarization state is higher than the diffraction efficiency of the second waveguide layer for light with the first polarization state, and the diffraction efficiency of the second waveguide layer for light with a second polarization state is higher than the diffraction efficiency of the first waveguide layer for light with the second polarization state.
[0013] In a second aspect, an embodiment of the present application further provides a display device, comprising an optical engine and the optical waveguide as described above, wherein the optical engine is used to emit the light, and the light forms a first light with uniform brightness after propagating through the optical waveguide.
[0014] In a third aspect, an embodiment of the present application further provides a head-up display system, comprising a display glass and the display device as described above, wherein a first light beam emitted by the display device reaches the display glass and is reflected to a target observation position.
[0015] Therefore, the present application provides an optical waveguide, a display device and a head-up display system, wherein the optical waveguide comprises: at least two waveguide layers, a plurality of the waveguide layers are stacked, each of the waveguide layers comprises an incoupling region and an outcoupling region, the incoupling region is located in the outcoupling region corresponding to the waveguide layer, the outcoupling region of each waveguide layer has a plurality of bright stripe regions, after the light is coupled into the waveguide layer from the incoupling region, it propagates to the outcoupling region and is emitted, and the brightness of the light emitted from the bright stripe region of the outcoupling region is higher than the brightness of the light emitted from other regions of the outcoupling region except the bright stripe region, and the bright stripe regions on different waveguide layers do not overlap. The present application sets the bright stripe regions on the plurality of waveguide layers not to overlap, so that the image light emitted from each waveguide layer does not overlap at the same position, further improving the uniformity of the light emitted from the entire optical waveguide, thereby achieving high display efficiency and high uniformity display effect of the optical waveguide.
[0016] Other features and advantages of the embodiments of the present application will be described in the subsequent description, and partly become apparent from the description, or can be understood by practicing the embodiments of the present application. The purposes and other advantages of the embodiments of the present application can be realized and obtained by the structures specifically pointed out in the written description, claims, and drawings. BRIEF DESCRIPTION OF THE DRAWINGS
[0017] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the drawings required for use in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For those skilled in the art, other drawings can be obtained based on these drawings without creative work.
[0018] Figure 1 A schematic structural diagram of an optical waveguide according to an embodiment of the present application is shown.
[0019] Figure 2 A schematic diagram of an initial propagation direction of a waveguide layer according to an embodiment of the present application is shown.
[0020] Figure 3 A schematic top view of the distribution of bright stripe regions of a waveguide layer according to an embodiment of the present application is shown.
[0021] Figure 4 A schematic diagram of the overall structure of another optical waveguide according to an embodiment of the present application is shown.
[0022] Figure 5 A schematic diagram showing an initial propagation direction of an optical waveguide according to an embodiment of the present application is shown.
[0023] Figure 6 A schematic top view of the distribution of bright stripe regions of an optical waveguide according to an embodiment of the present application is shown.
[0024] Figure 7 A schematic diagram of the grating vector directions of a first coupling region and a second coupling region of an embodiment of the present application is shown.
[0025] Figure 8 A schematic diagram of the grating vector directions of a first out-coupling region and a second out-coupling region in an embodiment of the present application is shown.
[0026] Fig. 9 A schematic diagram of the grating vector directions of another first coupling region and a second coupling region of an embodiment of the present application is shown.
[0027] Fig.10 A schematic structural diagram of a display device according to an embodiment of the present application is shown.
[0028] Fig.11 A schematic structural diagram of a head-up display system according to an embodiment of the present application is shown. DETAILED DESCRIPTION
[0029] In order to make those skilled in the art better understand the present application scheme, the technical scheme in the present application embodiment will be clearly and completely described below in conjunction with the drawings in the present application embodiment. Obviously, the described embodiment is only a part of the present application embodiment, rather than all the embodiments. The components of the present application embodiment usually described and shown in the drawings here can be arranged and designed in various different configurations. Therefore, the following detailed description of the embodiments of the present application provided in the drawings is not intended to limit the scope of the present application for protection, but merely represents the selected embodiment of the present application. Based on the embodiments of the present application, all other embodiments obtained by those skilled in the art without making creative work belong to the scope of protection of the present application.
[0030] It should be noted that similar reference numerals and letters represent similar items in the following drawings, so once an item is defined in one drawing, it does not need to be further defined and explained in subsequent drawings. At the same time, in the description of this application, the terms "first", "second", etc. are only used to distinguish the description and cannot be understood as indicating or implying relative importance.
[0031] The decoupling region of the central coupling waveguide usually uses a two-dimensional grating to achieve the decoupling of light, and the two-dimensional grating has diffraction orders in multiple directions, which can achieve light pupil expansion while achieving light decoupling. Specifically, the central coupling waveguide has a coupling region and a decoupling region. When light enters the coupling region of the central coupling waveguide, it is diffracted on the grating in the coupling region and coupled into the waveguide. Then, the light propagates in the waveguide until it propagates to the decoupling region, and then diffracts on the grating in the decoupling region to couple out of the waveguide. In other words, when the light propagates from the coupling region to the decoupling region, it has multiple initial propagation directions. Further, the direction in which the 0th order reflection propagation occurs after the light is coupled into the waveguide can be called the initial propagation direction. Further, according to the characteristics of the central coupling waveguide and the two-dimensional grating, once the light is coupled into the waveguide along the initial propagation direction, it will immediately reach the two-dimensional grating in the decoupling region, so that part of the light is coupled out of the waveguide from the decoupling region, and the remaining light that has not been coupled out continues to propagate in the waveguide and is coupled out one by one during the propagation process. That is to say, when the 0th order reflected light is the light with the highest energy proportion in the diffracted light generated when the light propagates in the out-coupling zone, the light propagating in the waveguide along the initial propagation direction will have a shorter propagation distance and more out-coupling times, that is, the out-coupling area will have more light out-coupling in the initial propagation direction, resulting in the final waveguide output image having a higher brightness along the coupling direction, and the output image presents an uneven brightness distribution, which seriously deteriorates the display effect of the center-coupled waveguide.
[0032] See also Figure 1 , Figure 1 A schematic structural diagram of an optical waveguide according to an embodiment of the present application is shown. The optical waveguide includes at least two waveguide layers 110, and the plurality of waveguide layers 110 are stacked one on another, so that light emitted from each waveguide layer 110 can be incident on the next waveguide layer 110. Each waveguide layer 110 includes an incoupling region 111 and an outcoupling region 112. The incoupling region 111 is located in the outcoupling region 112 of the corresponding waveguide layer 110, or the projection of the incoupling region 111 toward the outcoupling region 112 is located in the outcoupling region 112 of the corresponding waveguide layer 110. The outcoupling region 112 of each waveguide layer 110 has a plurality of bright strip regions 113, and the bright strip regions 113 on the outcoupling regions 112 of different waveguide layers 110 do not overlap.
[0033] In this embodiment, after entering the optical waveguide, the light is coupled into the waveguide layer from the coupling-in region 111 of a waveguide layer 110 and propagates to the coupling-out region 112 by total reflection, thereby exiting the waveguide layer 110. Since the plurality of waveguide layers 110 are stacked one on another, the light exiting the waveguide layer 110 can continue to enter the next waveguide layer 110. Moreover, for any waveguide layer 110, the brightness of the light emitted from the bright stripe region 113 of its coupling-out region 112 is higher than the brightness of the light emitted from other regions of its coupling-out region 112, wherein the other regions may refer to the remaining regions on the coupling-out region except the bright stripe region 113. It should be understood that, for a waveguide layer, the coupling-in region has a certain coupling-in efficiency, that is, the light incident on the waveguide layer cannot be fully coupled into the waveguide layer, and part of the incident light will directly transmit through the waveguide layer and enter the next waveguide layer, thereby coupling from the coupling-in region of the next waveguide layer into the next waveguide layer for propagation, and the outcoupled light emitted from the outcoupling region of a waveguide layer will also be transmitted through the next waveguide layer after being emitted to the next waveguide layer, and so on.
[0034] Specifically, by setting the bright stripe regions 113 on the outcoupling regions 112 of different waveguide layers 110 not to overlap, as an implementation, the bright stripe regions 113 of different waveguide layers can be made complementary to each other, wherein the bright stripe regions 113 of different waveguide layers are complementary to each other means that along the projection direction perpendicular to the output image, the edges of the bright stripe regions on different waveguide layers appear to be nearly overlapped or exactly overlapped. It should be noted that Figure 1 The bright stripe area in the figure is limited by the observation angle and is only for illustration. In practice, the bright stripe area can have various distributions and is not limited to Figure 1 In this way, the image light emitted from the bright stripe area of one waveguide layer can be transmitted through other areas of the next waveguide layer when it enters the next waveguide layer, and the image light coupled into the next waveguide layer for propagation also has a part coupled out from the bright stripe area of the waveguide layer, and this part of the coupled image light can supplement the light with lower brightness emitted from other areas of the previous waveguide layer, that is, the image light emitted from each waveguide layer has a part of light with lower brightness and a part of light with higher brightness, and the emission position of the light with higher brightness of each waveguide layer is different according to the different bright stripe areas, that is, the image light finally emitted by the optical waveguide can be complemented by the setting of the bright stripe areas that do not overlap each other, so that the first light propagated and emitted through multiple waveguide layers 110 has uniform brightness at any emission position, therefore, the image brightness distribution finally formed by the optical waveguide will be superimposed by the brightness of the light on the bright stripe areas that do not overlap each other on multiple waveguide layers, so as to achieve the high display efficiency and high uniformity display effect of the optical waveguide.
[0035] Optionally, the coupling-in region 111 and the coupling-out region 112 of the waveguide layer 110 are both two-dimensional gratings. According to the above analysis, the characteristics of the two-dimensional grating make the light coupled into the waveguide have multiple initial propagation directions, and the light will also have a brighter bright strip coupling-out region when coupling out of the optical waveguide. Therefore, please refer to Figure 2 and Figure 3 , Figure 2 A schematic diagram showing multiple initial propagation directions of a waveguide layer in an embodiment of the present application is shown. Figure 3 A schematic top view of the distribution of bright stripe regions of a waveguide layer according to an embodiment of the present application is shown. According to the above analysis, for the waveguide layer 110, the distribution of the bright stripe regions 113 of the waveguide layer 110 corresponds to the initial propagation direction of the coupling-in region 111. The waveguide layer has multiple initial propagation directions, and then the outcoupling region 112 of the waveguide layer 110 has multiple bright stripe regions 113. Further, the region other than the bright stripe region 113 on the outcoupling region 112 of each waveguide layer 110 can be defined as other regions. It can be understood that when light incident on a waveguide layer 110 is coupled into the waveguide layer 110 from the coupling-in region 111 in a certain initial propagation direction and propagates, and when it exits the waveguide layer 110 from the outcoupling region 110, it will be emitted from the corresponding bright stripe region 113 on the outcoupling region 110, and the brightness of the light will be significantly higher than the brightness of the light emitted from other regions on the outcoupling region.
[0036] As an implementation, see Figure 4 , wherein the optical waveguide includes a first waveguide layer 210 and a second waveguide layer 220, the first waveguide layer 210 has a first coupling region 211 and a first coupling region 212, the second waveguide layer 220 has a second coupling region 221 and a second coupling region 222, and the first coupling region 211 is arranged around the first coupling region 212, and the second coupling region 221 is arranged around the second coupling region 222. When the light propagates from the coupling region of the first waveguide layer to the coupling region, it has a plurality of first initial propagation directions, the first coupling region has a plurality of first bright strip regions, and the distribution of each of the first bright strip regions on the first coupling region corresponds to one of the first initial propagation directions; when the light propagates from the coupling region of the second waveguide layer to the coupling region, it has a plurality of second initial propagation directions, the second coupling region has a plurality of second bright strip regions, and the distribution of each of the second bright strip regions on the second coupling region corresponds to one of the second initial propagation directions.
[0037] For further information, see Figure 5 and Figure 6 , Figure 5 A schematic diagram of the initial propagation direction of an optical waveguide according to an embodiment of the present application is shown. Specifically, Figure 5a shows a schematic diagram of the first initial propagation direction of the first waveguide layer, Figure 5 b shows a schematic diagram of the second initial propagation direction of the second waveguide layer, Figure 5 c is a schematic diagram showing the initial propagation direction after the first waveguide layer and the second waveguide layer overlap; Figure 6 A schematic top view of the bright strip area distribution of an optical waveguide according to an embodiment of the present application is shown. Specifically, Figure 6 a shows a schematic diagram of the bright stripe area distribution of the first waveguide layer, Figure 6 b shows a schematic diagram of the bright stripe area distribution of the second waveguide layer, Figure 6 c shows a schematic diagram of the distribution of bright stripe regions after the first waveguide layer and the second waveguide layer overlap. It can be obtained that the first coupling region 211 has multiple first initial propagation directions, and accordingly, the first coupling region 212 has multiple corresponding first bright stripe regions, the second coupling region 221 has multiple second initial propagation directions, and accordingly, the second coupling region 222 has multiple corresponding second bright stripe regions, and the first bright stripe regions and the second bright stripe regions are complementary to each other, so that the positions of the image light of the first waveguide layer emitted from the first bright stripe region and the image light of the second waveguide layer emitted from the second bright stripe region on the final image are complementary to each other, that is, the brightness distribution of the image emitted by the optical waveguide is just completely filled by the complementary bright stripe regions of the first waveguide layer and the second waveguide layer, achieving high display efficiency and high uniformity of the display effect of the optical waveguide.
[0038] Optionally, the first coupling-in region and the first coupling-out region of the first waveguide layer are two-dimensional gratings, and the second coupling-in region and the second coupling-out region of the second waveguide layer are also two-dimensional gratings. Specifically, the two-dimensional grating has a grating vector K, and the grating vector is used to change the wave vector of the light incident on the grating, so that the propagation direction of the light after the grating is coupled into the waveguide layer becomes the same as the direction of the grating vector. It can be understood that the direction of the grating vector K can be used to characterize the initial propagation direction of the light when the grating is coupled into the waveguide layer. Therefore, please refer to Figure 7 and Figure 8 , Figure 7 Schematic diagram of grating vectors of the first coupling region and the second coupling region of the embodiment of the present application is shown, Figure 8A schematic diagram of grating vectors of a first out-coupling region and a second out-coupling region according to an embodiment of the present application is shown. It can be seen from the diagram that, for the first waveguide layer and the second waveguide layer, the grating unit on the first coupling-in region can be rotated 90° clockwise or counterclockwise as a whole to obtain the grating unit on the second coupling-in region. That is, the grating vector of the grating unit on the first coupling-in region differs from the grating vector of the grating unit on the second coupling-in region by 90° clockwise or counterclockwise, so that the initial propagation direction of the first waveguide layer is different from the grating vector of the grating unit on the second coupling-in region. The initial propagation directions of the second waveguide layer do not overlap with each other, and at the same time, the grating vector directions of the first out-coupling region and the first in-coupling region are opposite, and the grating vector directions of the second out-coupling region and the second in-coupling region are opposite, that is, the grating vector directions of the grating units in the first out-coupling region and the second out-coupling region also differ by 90° clockwise or counterclockwise, so that the initial propagation direction of the first waveguide layer and the initial propagation direction of the second waveguide layer do not overlap with each other, that is, the bright stripe region of the first waveguide layer and the bright stripe region of the second waveguide layer do not overlap with each other.
[0039] Furthermore, the width and divergence angle of the first bright stripe area and the second bright stripe area are variable. This is because the field of view (FOV) of the light source emitting light will affect the divergence angle and width of the bright stripe area, so the width and divergence angle of the first bright stripe area and the second bright stripe area can be adjusted by adjusting the FOV of the light source, so that the edge lines of the bright stripe area can be close to or even overlap each other under the premise that the first bright stripe area and the second bright stripe area do not overlap each other, thereby ensuring high complementarity between the bright stripe area of the first waveguide layer and the bright stripe area of the second waveguide layer, and achieving a better high uniformity display effect. Furthermore, in the process of preparing the first waveguide layer, the widths and divergence angles of the first bright stripe region and the second bright stripe region can be pre-set to different values according to requirements. At this time, the first bright stripe region and the second bright stripe region with different widths and divergence angles can be prepared by changing parameters such as the grating refractive index and grating period of the grating unit on the first outcoupling region, and changing parameters such as the grating refractive index and grating period of the grating unit on the second outcoupling region.
[0040] Optionally, the first coupling-in region of the first waveguide layer is a one-dimensional grating, the first coupling-out region is still a two-dimensional grating, the second coupling-in region of the second waveguide layer is also a one-dimensional grating, and the second coupling-out region is still a two-dimensional grating. Fig. 9 , Fig. 91 shows another schematic diagram of grating vectors of the first coupling-in region and the second coupling-in region according to an embodiment of the present application, wherein the grating vectors of the grating units on the first coupling-in region are perpendicular to the grating vectors of the grating units on the second coupling-in region, so that the initial propagation directions of the first waveguide layer and the second waveguide layer are orthogonal to each other, that is, the grating vector directions of the grating units on the first coupling-in region and the grating vector directions of the grating units on the second coupling-in region differ by 90° clockwise or counterclockwise, and at the same time, the grating vector directions of the first coupling-out region and the second coupling-out region can continue to refer to Figure 8 , that is, the grating vector direction of the grating unit on the first outcoupling area differs from the grating vector direction of the grating unit on the second outcoupling area by 90° clockwise or counterclockwise, and both the positive first-order diffraction light and the negative first-order light of the incident light can be coupled into the waveguide. Preferably, the one-dimensional grating can be a one-dimensional straight grating. According to the symmetry of the straight grating structure, when the incident field angle of the light source is also bilaterally symmetrical, the energy of the coupled light is the same. In addition, the width and divergence angle of the first bright strip area and the second bright strip area can be changed. The specific implementation method can refer to the above embodiment and will not be repeated here.
[0041] It should be noted that the grating structure of the first coupling region of the first waveguide layer and the grating structure of the second coupling region of the second waveguide layer are not limited to the above two examples. A solution in which one layer is one-dimensionally coupled and the other layer is two-dimensionally coupled can also be adopted, as long as the coupling directions are complementary, that is, the bright stripe areas on different waveguide layers are complementary. No further details will be given here.
[0042] Optionally, the diffraction efficiency of the first waveguide layer for light with a first polarization state is higher than the diffraction efficiency of the second waveguide layer for light with a first polarization state, and the diffraction efficiency of the second waveguide layer for light with a second polarization state is higher than the diffraction efficiency of the first waveguide layer for light with a second polarization state. Further, the first polarization state may be any one of a p polarization state and an s polarization state, and the second polarization state may be a polarization state opposite to the first polarization state. The two waveguide layers are provided with high diffraction efficiency for light with different polarization states, so that light with a certain polarization state in the natural light emitted by the light source can be efficiently diffracted into a certain waveguide layer, while light with another polarization state can be efficiently transmitted through the waveguide layer, thereby diffracted into the next waveguide layer, and the waveguide optimized under single polarization light has a higher working efficiency than the waveguide designed under natural light, so that two orthogonal polarization lights can be propagated in different waveguide layers to obtain higher energy transfer efficiency.
[0043] Therefore, the present application provides an optical waveguide, comprising: at least two waveguide layers, wherein the plurality of waveguide layers are stacked, each of the waveguide layers comprises an incoupling region and an outcoupling region, wherein the incoupling region or a projection of the incoupling region onto the outcoupling region is located in the outcoupling region, and the outcoupling region of each waveguide layer has a plurality of bright stripe regions, after light is coupled into the waveguide layer from the incoupling region, it propagates to the outcoupling region and is emitted, and the brightness of light emitted from the bright stripe region of the outcoupling region is higher than the brightness of light emitted from other regions of the outcoupling region, and the bright stripe regions on different waveguide layers do not overlap, so that the light incident on the optical waveguide forms a first light after propagating through the plurality of waveguide layers, and the brightness of the first light when emitted from any exit position of the optical waveguide is the same. The present application sets non-overlapping bright stripe areas on multiple waveguide layers so that the light emitted from each waveguide layer does not overlap at the same position. The resulting image brightness distribution will be filled by the non-overlapping bright stripe areas of the multiple waveguide layers, thereby achieving high display efficiency and high uniformity of the optical waveguide display effect.
[0044] See also Fig.10 , Fig.10 A display device shown in an embodiment of the present application is shown, comprising a light source 301 and an optical waveguide 302 as described in the above embodiment, wherein the light source 301 is used to emit light, and the light is coupled into the optical waveguide 302 to form a first light after propagation, and the first light has the same brightness when emitted from any exit position of the optical waveguide. The specific implementation method can refer to the above embodiment, and will not be repeated here.
[0045] See also Fig.11 , Fig.11 A head-up display system shown in an embodiment of the present application is shown, including a display glass 401 and a display device 402 as described in the above embodiment, and a first light emitted by the display device 402 reaches the display glass 401 and is reflected to a target observation position, which generally refers to a human eye. The specific implementation method can refer to the above embodiment, and will not be repeated here.
[0046] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present application, rather than to limit it. Although the present application has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present application.
Claims
1. An optical waveguide, characterized in that: The invention comprises at least two waveguide layers, wherein a plurality of the waveguide layers are stacked, each of the waveguide layers comprises an incoupling region and an outcoupling region, the incoupling region or a projection of the incoupling region toward the outcoupling region is located in the outcoupling region of the corresponding waveguide layer, and the outcoupling region of each waveguide layer has a plurality of bright stripe regions, and when light is coupled into the waveguide layer from the incoupling region and propagates to the outcoupling region, the brightness of light emitted from the bright stripe region of the outcoupling region is higher than the brightness of light emitted from other regions of the outcoupling region except the bright stripe region; Wherein, the bright stripe regions on different waveguide layers do not overlap.
2. The optical waveguide according to claim 1, characterized in that The bright stripe regions on different waveguide layers complement each other, so that the brightness of the first image light formed by the light incident on the optical waveguide after propagating through the multiple waveguide layers is uniform.
3. The optical waveguide according to claim 2, characterized in that In each of the waveguide layers, when light propagates from the coupling-in region to the coupling-out region of the waveguide layer, the light has a plurality of initial propagation directions, and one of the bright stripe regions corresponds to one of the initial propagation directions; wherein the plurality of initial propagation directions of different waveguide layers are different.
4. The optical waveguide according to claim 1, characterized in that The optical waveguide comprises a first waveguide layer and a second waveguide layer, the first waveguide layer has a first coupling-in region and a first coupling-out region, the second waveguide layer has a second coupling-in region and a second coupling-out region, the first coupling-out region is arranged around the first coupling-in region, and the second coupling-out region is arranged around the second coupling-in region; When the light propagates from the coupling region of the first waveguide layer to the coupling region, the light has a plurality of first initial propagation directions, the first coupling region has a plurality of first bright strip regions, and the distribution of each of the first bright strip regions on the first coupling region corresponds to one of the first initial propagation directions; when the light propagates from the coupling region of the second waveguide layer to the coupling region, the light has a plurality of second initial propagation directions, the second coupling region has a plurality of second bright strip regions, and the distribution of each of the second bright strip regions on the second coupling region corresponds to one of the second initial propagation directions.
5. The optical waveguide according to claim 4, characterized in that The width and divergence angle of the first bright stripe area are both variable, and the width and divergence angle of the second bright stripe area are both variable, wherein the divergence angle of the first bright stripe area refers to the angle of one end of the first bright stripe area close to the first coupling area, and the divergence angle of the second bright stripe area refers to the angle of one end of the second bright stripe area close to the second coupling area.
6. The optical waveguide according to claim 4, characterized in that The first coupling-in region and the first coupling-out region are two-dimensional gratings, and the second coupling-in region and the second coupling-out region are also two-dimensional gratings; The grating vector direction of the grating unit on the first coupling-in region differs from the grating vector direction of the grating unit on the second coupling-in region by 90° clockwise or counterclockwise, the grating vector direction of the grating unit on the first coupling-out region is opposite to the grating vector direction of the first coupling-in region, and the grating vector direction of the grating unit on the second coupling-out region is opposite to the grating vector direction of the second coupling-in region.
7. The optical waveguide according to claim 4, characterized in that The first coupling-in region and the second coupling-in region are one-dimensional gratings, and the first coupling-out region and the second coupling-out region are two-dimensional gratings. The grating vector direction of the grating unit on the first coupling-in region differs from the grating vector direction of the grating unit on the second coupling-in region by 90° clockwise or counterclockwise, and the grating vector direction of the grating unit on the first coupling-out region differs from the grating vector direction of the grating unit on the second coupling-out region by 90° clockwise or counterclockwise.
8. The optical waveguide according to claim 4, characterized in that The diffraction efficiency of the first waveguide layer for light with a first polarization state is higher than the diffraction efficiency of the second waveguide layer for light with the first polarization state, and the diffraction efficiency of the second waveguide layer for light with a second polarization state is higher than the diffraction efficiency of the first waveguide layer for light with the second polarization state.
9. A display device, characterized in that: It comprises an optical machine and the optical waveguide as described in any one of claims 1 to 8, wherein the optical machine is used to emit the light, and the light forms a first light with uniform brightness after propagating through the optical waveguide.
10. A head-up display system, characterized in that: The device comprises a display glass and the display device as claimed in claim 9, wherein a first light emitted by the display device reaches the display glass and is reflected to a target observation position.