Light guide module and head-up display system

Abstract

The utility model relates to a light guide module and a head-up display system. The light guide module comprises a first waveguide layer, a second waveguide layer, a first coupling-out device and a second coupling-out device, wherein the first waveguide layer and the second waveguide layer are stacked; the first coupling-out device is arranged on the first waveguide layer; the first waveguide layer is used for transmitting a first light beam, the first coupling-out device is provided with a first coupling-out part and a non-coupling-out part which are adjacent to each other, and the first coupling-out part is used for coupling out the first light beam propagating in the first waveguide layer. The second waveguide layer is used for transmitting a second light beam, the second coupling-out device is provided with a second coupling-out part and a light transmitting part which are adjacent to each other, and the second coupling-out part is used for coupling out the second light beam propagating in the second waveguide layer to a target projection position; the light transmitting part is used for transmitting the first light beam coupled out of the first waveguide layer so that the first light beam coupled out of at least part of the first waveguide layer can be emitted to a target projection position. According to the light guide module, the phenomenon of stray light is avoided.

Description

Technical Field

[0001] The present application relates to the technical field of display devices, and particularly relates to a light guide module and a head-up display system. Background Art

[0002] In-vehicle head-up display devices are becoming an important way for drivers to obtain information about the vehicle being driven. They can project driving condition and road condition information in real time in the normal line of sight of the driver, making driving more comfortable and safe. The image light emitted by the image generation unit of the head-up display is transmitted to the front windshield of the vehicle through a spatial optical system, and finally enters the human eye after being reflected by the windshield. Among them, the spatial optical system usually adopts a light waveguide and holographic optical element solution.

[0003] Existing head-up display devices usually adopt a double-layer waveguide solution to improve the white field performance of the waveguide. In the double-layer waveguide solution, stray light is easily generated when light propagates between different waveguides. The stray light entering the human eye will affect the viewing experience and also cause a decrease in the image light efficiency. Summary of the Utility Model

[0004] Embodiments of the present application provide a light guide module and a head-up display system.

[0005] In a first aspect, embodiments of the present application provide a light guide module for guiding the light of a light source to a target projection position. The light source is used to emit a first light beam and a second light beam. The light guide module includes a first waveguide layer and a second waveguide layer stacked on top of each other, a first coupling-out device disposed on the first waveguide layer, and a second coupling-out device disposed on the second waveguide layer. The first waveguide layer is used to transmit the first light beam. The first coupling-out device has an adjacent first coupling-out portion and a non-coupling-out portion, and the first coupling-out portion is used to couple out the first light beam propagating in the first waveguide layer. The second waveguide layer is used to transmit the second light beam. The second coupling-out device has an adjacent second coupling-out portion and a light-transmitting portion. The second coupling-out portion is used to couple out the second light beam propagating in the second waveguide layer to the target projection position, and the light-transmitting portion is used to transmit the first light beam coupled out from the first waveguide layer so that the first light beam coupled out from at least part of the first waveguide layer is emitted to the target projection position.

[0006] In some alternative embodiments, when the second waveguide layer is projected onto the plane where the first waveguide layer is located, at least part of the orthographic projection of the second coupling-out portion coincides with the non-coupling-out portion, and at least part of the orthographic projection of the light-transmitting portion coincides with the first coupling-out portion.

[0007] In some alternative embodiments, the wavelength of the first light beam is in a first wavelength band, the wavelength of the second light beam is in a second wavelength band, the first wavelength band and the second wavelength band are different, the second waveguide layer is used to be disposed between the target projection position and the first waveguide layer, and the central wavelength of the first wavelength band is less than the central wavelength of the second wavelength band.

[0008] In some alternative embodiments, the light guiding module further includes a first coupling grating and a second coupling grating. The first coupling grating is disposed on the surface of the first waveguide layer, and is configured to couple the first light beam into the first waveguide layer for propagation. The second coupling grating is disposed on the surface of the second waveguide layer, and is configured to couple the second light beam into the second waveguide layer for propagation. The first coupling grating is disposed on the side of the first waveguide layer facing away from the second waveguide layer, and the second coupling grating is disposed on the side of the second waveguide layer facing the first waveguide layer; or the first coupling grating is disposed on the side of the first waveguide layer facing the second waveguide layer, and the second coupling grating is disposed on the side of the second waveguide layer facing away from the first waveguide layer; or the first coupling grating and the second coupling grating are respectively disposed on the opposite sides of the first waveguide layer and the second waveguide layer; or the first coupling grating and the second coupling grating are respectively disposed on the facing sides of the first waveguide layer and the second waveguide layer.

[0009] In some alternative embodiments, when the second waveguide layer is projected onto the plane where the first waveguide layer is located, the orthographic projection of the second coupling grating at least partially coincides with the first coupling grating. The light guiding module further includes a baffle, which is disposed opposite to the first coupling grating or the second coupling grating.

[0010] In some alternative embodiments, the first light output device is disposed on the side of the first waveguide layer facing away from the second waveguide layer, and the second light output device is disposed on the side of the second waveguide layer facing the first waveguide layer; or the first light output device is disposed on the side of the first waveguide layer facing the second waveguide layer, and the second light output device is disposed on the side of the second waveguide layer facing away from the first waveguide layer; or the first light output device and the second light output device are respectively disposed on the opposite sides of the first waveguide layer and the second waveguide layer; or the first light output device and the second light output device are respectively disposed on the facing sides of the first waveguide layer and the second waveguide layer.

[0011] In some alternative embodiments, the number of the first light output portions and the number of the non-light output portions are both set to be plural. The plural first light output portions and the plural non-light output portions are alternately arranged in a first direction and a second direction; the number of the second light output portions and the number of the light transmitting portions are both set to be plural. The plural second light output portions and the plural light transmitting portions are alternately arranged in the first direction and the second direction; the first direction and the second direction intersect.

[0012] In some alternative embodiments, the sizes of the first light output portion, the non-light output portion, the second light output portion, and the light transmitting portion are the same, and the maximum width of the non-light output portion is less than or equal to 4 mm.

[0013] In some alternative embodiments, both the first waveguide layer and the second waveguide layer are glass substrates; an area with a grating structure within the range of the glass substrate corresponding to the first coupling-out device forms a first coupling-out portion; an area within the range of the glass substrate corresponding to the first coupling-out device without a grating structure forms a non-coupling-out portion; an area with a grating structure within the range of the glass substrate corresponding to the second coupling-out device forms a second coupling-out portion; an area within the range of the glass substrate corresponding to the second coupling-out device without a grating structure forms a light-transmitting portion.

[0014] In a second aspect, an embodiment of the present application further provides a head-up display system, including a light source, any one of the above-mentioned light guide modules, and a windshield. The light source is configured to emit a first light beam and a second light beam. The light guide module is disposed on the light-emitting optical path of the light source and is configured to conduct at least part of the first light beam and the second light beam to a target projection position, and the target projection position is located on the windshield. The windshield is configured to reflect at least part of the first light beam and the second light beam to a human eye observation position.

[0015] Compared with the prior art, when the light guide module provided by the embodiment of the present application operates, the light source emits a first light beam and a second light beam. The first light beam is coupled into the first waveguide layer by the coupling-in device and propagates in the first waveguide layer to the first coupling-out device, and the first light beam is coupled out of the first waveguide layer through the first coupling-out portion. Taking the case where the second waveguide layer is located on the side of the first waveguide layer away from the light source as an example, after the first light beam is coupled out of the first waveguide layer through the first coupling-out portion, it transmits through the light-transmitting portion of the second waveguide layer and propagates to the target projection position. The coupling-out areas on the first waveguide layer and the second waveguide layer are staggeredly arranged, so that the first light beam coupled out of the first waveguide layer will enter the light-transmitting area of the second waveguide layer, and thus directly transmit through the second waveguide layer and propagate to the target projection position. The light guide module of the embodiment of the present application avoids the phenomenon that the first light beam with a different wavelength band from the second light beam diffracts at the second coupling-out portion of the second waveguide layer to generate stray light. On the one hand, it reduces the impact on the human eye observation experience, and on the other hand, it improves the image light efficiency of the first light beam. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] In order to more clearly illustrate the technical solutions of the present application, the drawings required for implementation will be briefly introduced below. Obviously, the drawings in the following description are only some implementations of the present application. For those of ordinary skill in the art, other drawings can be obtained based on these drawings without creative efforts.

[0017] Figure 1 is a simplified structural schematic diagram of a vehicle provided by an embodiment of the present application.

[0018] Figure 2 is a simplified structural schematic diagram of a head-up display system provided by an embodiment of the present application.

[0019] Figure 3Yes Figure 2 A plan view of a first waveguide layer and a first coupling-out device of a light guiding module of the head-up display system shown.

[0020] Figure 4 Yes Figure 3 A plan view of the first coupling-out device of the light guiding module shown.

[0021] Figure 5 Yes Figure 2 A schematic structural view of another embodiment of the light guiding module shown.

[0022] Figure 6 Yes Figure 2 A plan view of a second waveguide layer and a second coupling-out device of the light guiding module shown.

[0023] Figure 7 Yes Figure 6 A plan view of the second coupling-out device of the light guiding module shown.

[0024] Figure 8 Yes Figure 2 A schematic structural view of yet another embodiment of the light guiding module shown.

[0025] Reference numeral description: 100, light guiding module; 10, first waveguide layer; 12, first surface; 14, second surface; 30, second waveguide layer; 32, third surface; 34, fourth surface; 50, coupling-in device; 52, first coupling-in grating; 54, second coupling-in grating; 70, first coupling-out device; 72, first coupling-out portion; 74, non-coupling-out portion; 90, second coupling-out device; 92, second coupling-out portion; 94, light transmissive portion; 200, head-up display system; 201, light source; 300, vehicle; 301, vehicle body; 202, front windshield. Detailed embodiments

[0026] Next, the technical solutions in the embodiments of the present application will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present application. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all of the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present application without creative efforts shall fall within the protection scope of the present application.

[0027] In the description of the present invention, it should be understood that the orientation or positional relationship indicated by the terms "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc. is based on the orientation or positional relationship shown in the drawings, and is only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and thus should not be construed as a limitation of the present invention.

[0028] In the description of the present invention, it should be noted that unless otherwise clearly defined and limited, the terms "installed", "connected", and "coupled" should be understood in a broad sense. For example, it may be a fixed connection, a detachable connection, or an integral connection. It may be a mechanical connection or an electrical connection. It may be directly connected or indirectly connected through an intermediate medium, and it may be the communication inside two components. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0029] Please refer to Figure 1 , an embodiment of the present application provides a head-up display system 200. The head-up display system 200 can be applied to a vehicle 300, and is used to project the vehicle condition information, road condition information, etc. of the vehicle 300 in real time in the line of sight direction of the driver during normal driving, improving the driving safety and comfort. The vehicle 300 includes a vehicle body 301 and the above-mentioned head-up display system 200. Please also refer to Figure 1 and Figure 2, in this embodiment, the head-up display system 200 may include a light source 201, a light guide module 100, and a windshield 202. In this embodiment, the windshield 202 is the front windshield of the vehicle 300. The windshield 202 is fixedly connected to one end of the vehicle body 301 in the advancing direction, and a cab for the driver to operate is formed between the windshield 202 and the vehicle body 301. The light source 201 and the light guide module 100 are disposed inside the vehicle body 301, and are used to project vehicle condition information, road condition information, etc. of the vehicle 300 onto the windshield 202. The light source 201 is used to emit a first light beam A and a second light beam B. Specifically, the windshield 202 is used to reflect at least part of the first light beam A and the second light beam B to the human eye observation position. This specification does not limit the specific installation positions of the light source 201 and the light guide module 100 inside the vehicle body 301. For example, the light source 201 and the light guide module 100 may be disposed above the windshield 202 (for example, installed at the ceiling of the vehicle 300), or may be disposed below the windshield 202 (for example, on the instrument panel of the vehicle 300). Among them, the light source 201 may be an image display, which is used to display an image source (for example, used to display multimedia content such as images), and emit image source light rays carrying image information. The light guide module 100 is disposed on one side of the light source 201. Specifically, the light guide module 100 is located on the optical path of the image source light rays emitted by the light source 201. The light guide module 100 is used to conduct at least part of the first light beam A and the second light beam B to the target projection position. Among them, the "target projection position" may be the position of the windshield 202 in the normal driving line of sight of the driver. The target projection position (windshield 202) and the light source 201 may be located on opposite sides of the light guide module 100, or the target projection position (windshield 202) and the light source 201 may also be located on the same side of the light guide module 100.

[0030] In this embodiment, the light source 201 is configured to emit a first light beam A and a second light beam B. The wavelength of the first light beam A is in a first wavelength band, and the wavelength of the second light beam B is in a second wavelength band. In a specific embodiment, the first wavelength band and the second wavelength band are different. In other embodiments, the first wavelength band and the second wavelength band may also be the same. This specification does not limit the specific number of the light sources 201. For example, the number of the light sources 201 may be set to one, and both the first light beam A and the second light beam B are emitted by this light source 201, and the first light beam A and the second light beam B are in the same direction. Alternatively, the number of the light sources 201 may also be set to two. If the two light sources 201 are arranged on opposite sides of the light guiding module 100, then the first light beam A and the second light beam B are not in the same direction. In this embodiment, the number of the light sources 201 is set to one, and the light source 201 is located on the side of the light guiding module 100 away from the target projection position. The first light beam A and the second light beam B are image light or light source light emitted by the light source 201. This specification does not limit the specific types of the first light beam A and the second light beam B. As an example, the first light beam A may be red light, and the second light beam B may be blue light; or the first light beam A may be blue light, and the second light beam B may be red light.

[0031] The light guiding module 100 may include a first waveguide layer 10, a second waveguide layer 30, a first coupling-out device 70, and a second coupling-out device 90. The first waveguide layer 10 and the second waveguide layer 30 are stacked. The first coupling-out device 70 is disposed on the first waveguide layer 10. The first coupling-out device 70 has an adjacent first coupling-out portion 72 and a non-coupling-out portion 74. The first coupling-out portion 72 is configured to couple out the first light beam A propagating in the first waveguide layer 10 from the first waveguide layer 10. The non-coupling-out portion 74 is a concept opposite to the first coupling-out portion 72. The first light beam A cannot escape from the first waveguide layer 10 by breaking the total reflection condition through diffraction at the non-coupling-out portion 74; however, it should be noted that this does not mean that no light escapes from the position corresponding to the non-coupling-out portion 74. For example, in certain specific cases, a part of the first light beam A / second light beam B incident on the non-coupling-out portion 74 may be transmitted or reflected by the non-coupling-out portion 74 and then escape. In a specific embodiment, the non-coupling-out portion 74 may be a light-transmitting portion. Specifically, it may be a glass substrate without a grating structure thereon; or the non-coupling-out portion 74 may also be light-impermeable. In this case, the corresponding area of the non-coupling-out portion 74 has no grating structure and is blackened.

[0032] The second output device 90 is disposed in the second waveguide layer 30. The second output device 90 has adjacent second output portions 92 and light-transmitting portions 94. The second output portion 92 is configured to couple out a second light beam B propagating in the second waveguide layer 30 to a target projection position. The light-transmitting portion 94 is configured to transmit the first light beam A coupled out from the first waveguide layer 10 so that the first light beam A coupled out from the first waveguide layer 10 is emitted to the target projection position. Projecting the second waveguide layer 30 onto the plane where the first waveguide layer 10 is located, at least a part of the orthographic projection of the second output portion 92 coincides with the non-output portion 74, and at least a part of the orthographic projection of the light-transmitting portion 94 coincides with the first output portion 72. When the orthographic projection of the second output portion 92 coincides with the non-output portion 74, substantially all of the first light beam A coupled out from the first waveguide layer 10 can be emitted from the second waveguide layer 30, and a better effect of reducing stray light can be achieved.

[0033] During operation, the light source 201 emits the first light beam A and the second light beam B. The first light beam A is coupled into the first waveguide layer 10 and propagates in the first waveguide layer 10 to the first output device 70. The first light beam A is coupled out of the first waveguide layer 10 via the first output portion 72. Taking the case where the second waveguide layer 30 is located on the side of the first waveguide layer 10 away from the light source 201 as an example, after the first light beam A is coupled out of the first waveguide layer 10 via the first output portion 72, it is transmitted through the light-transmitting portion 94 of the second waveguide layer 30 and propagates to the target projection position. The second light beam B is coupled into the second waveguide layer 30 via the coupling device 50 and conducts in the second waveguide layer 30 to the second output device 90. The second light beam B is coupled out of the second waveguide layer 30 via the second output portion 92 and propagates to the target projection position.

[0034] The first light beam A coupled out from the first waveguide layer 10 will be incident on the light-transmitting portion 94 of the second waveguide layer 30, and thus directly transmit through the second waveguide layer 30 and propagate to the target projection position. The light guide module 100 of the embodiment of the present application avoids the phenomenon of stray light generated by diffraction of the first light beam A by the output region of the second waveguide layer 30. On the one hand, it reduces the impact on the human eye observation experience, and on the other hand, it improves the image light efficiency of the first light beam A.

[0035] In this embodiment, both the first waveguide layer 10 and the second waveguide layer 30 are guiding structures for transmitting optical frequency electromagnetic waves composed of a light-transparent medium (such as quartz glass). They are devices for guiding waves to propagate therein, and are used to limit the propagation path of light beams in space. When the propagation angle of the light beam satisfies the total reflection condition, it can only propagate within the waveguide layer. This specification does not limit the specific types of the first waveguide layer 10 and the second waveguide layer 30. Both the first waveguide layer 10 and the second waveguide layer 30 can be made into very thin and light flat glass forms. In this embodiment, the first waveguide layer 10 and the second waveguide layer 30 can be glass plates. The refractive index of the glass plate is n, the thickness is d, and the total reflection critical angle of the glass plate is θ0 = arcsin(n a / n), where n a is the refractive index of air. The larger the refractive index n of the glass plate, the smaller the total reflection critical angle θ0. At this time, the angular range in which total reflection can occur in the first waveguide layer 10 and the second waveguide layer 30 increases, increasing the design freedom.

[0036] This specification does not limit the specific position of the first waveguide layer 10. For example, the first waveguide layer 10 can be disposed between the light source 201 and the second waveguide layer 30, or the first waveguide layer 10 can be disposed on the side of the second waveguide layer 30 facing away from the light source 201. In a specific embodiment, the target projection position and the light source 201 can be located on opposite sides of the light guide module 100, the first waveguide layer 10 is disposed close to the light source 201, and the second waveguide layer 30 is disposed close to the target projection position; in another specific embodiment, the target projection position and the light source 201 are both located on the same side of the light guide module 100, the second waveguide layer 30 is disposed close to the light source 201 and the light guide module 100, and the first waveguide layer 10 is disposed away from the light source 201 and the target projection position. In this embodiment, the central wavelength of the first wavelength band is less than the central wavelength of the second wavelength band, the first waveguide layer 10 is located between the light source 201 and the second waveguide layer 30, and the second waveguide layer 30 is used to be disposed between the target projection position and the first waveguide layer 10. The first waveguide layer 10 may include a first surface 12 and a second surface 14, and the first surface 12 and the second surface 14 face away from each other. Among them, the first surface 12 faces the light source 201, and the first surface 12 serves as the incident surface of the first waveguide layer 10. In this embodiment, the first waveguide layer 10 is integrally presented as a flat plate, so the first surface 12 and the second surface 14 can be planes. In other embodiments, the first waveguide layer 10 can be presented as a curved plate, and the first surface 12 and the second surface 14 can be a concave surface and a convex surface respectively; the outer shape of the first waveguide layer 10 can be presented as a circular plate, and the first surface 12 and the second surface 14 can both be arc-shaped surfaces.

[0037] In this embodiment, the light guide module 100 may further include a first coupling grating 52 and a second coupling grating 54, and the first coupling grating 52 and the second coupling grating 54 are respectively disposed on the surfaces of the first waveguide layer 10 and the second waveguide layer 30. Among them, the first coupling grating 52 is disposed on the surface of the first waveguide layer 10, and it is used to change the propagation angle of the first light beam A so that it can meet the propagation conditions of total reflection in the first waveguide layer 10. This specification does not limit the specific type of the first coupling grating 52. For example, the first coupling grating 52 may include at least one of the following grating structures: a straight grating, a helical grating, a blazed grating, a surface relief grating, and a volume grating. A grating is a dispersion element that uses the interference and diffraction phenomena of light for spectroscopy. In this embodiment, the first waveguide layer 10 also serves as the substrate of the first coupling grating 52, so that the first coupling grating 52 can be attached thereto.

[0038] See also Figure 3 and Figure 4 The first outcoupling device 70 is disposed on the surface of the first waveguide layer 10. The first outcoupling portion 72 of the first outcoupling device 70 is used to disrupt the propagation of the first light beam A within the first waveguide layer 10, allowing the first light beam A to be coupled out of the first waveguide layer 10. In one specific embodiment, the first waveguide layer 10 is a glass substrate. The region of the glass substrate corresponding to the first outcoupling device 70 where the grating structure is disposed forms the first outcoupling portion 72. The region of the glass substrate corresponding to the first outcoupling device 70 where the grating structure is not disposed forms the non-outcoupling portion 74. In other words, the non-outcoupling portion 74 is a glass unit and lacks the function of coupling out image light. In one specific embodiment, a plurality of non-outcoupling portions 74 and a plurality of first outcoupling portions 72 are provided, and the plurality of first outcoupling portions 72 and the plurality of non-outcoupling portions 74 are alternately arranged in a first direction X and a second direction Y. The first direction X and the second direction Y intersect (e.g., are perpendicular to each other). The first direction X can be the length direction of the first waveguide layer 1, and the second direction Y can be the width direction of the first waveguide layer 10. The plurality of first outcoupling portions 72 are spaced apart from each other in both the first direction X and the second direction Y, and the plurality of non-outcoupling portions 74 are spaced apart from each other in both the first direction X and the second direction Y. Each first outcoupling portion 72 is adjacent to a non-outcoupling portion 74. In this arrangement, the first outcoupling portions and the non-outcoupling portions are staggered, resulting in better display uniformity. In another specific embodiment, the number of non-outcoupling portions 74 and first outcoupling portions 72 is also provided, and the plurality of first outcoupling portions 72 and the plurality of non-outcoupling portions 74 are alternately arranged in the first direction X, and the plurality of first outcoupling portions 72 are sequentially arranged in the second direction Y, wherein the first direction X and the second direction Y intersect. Furthermore, the first direction X and the second direction Y are perpendicular, the first direction X can be the length direction of the first waveguide layer 1, and the second direction Y can be the width direction of the first waveguide layer 10. The plurality of first outcoupling portions 72 are spaced apart from each other in the first direction X and adjacent to each other in the second direction Y, and the plurality of non-outcoupling portions 74 are spaced apart from each other in the first direction X and adjacent to each other in the second direction Y. This arrangement can also reduce stray light, but the final display uniformity is slightly worse.

[0039] Both the first coupling output part 72 and the non-coupling output part 74 are substantially cube-shaped, and the projections of the first coupling output part 72 and the non-coupling output part 74 on the surface of the first waveguide layer 10 are in a grid pattern. Since the non-coupling output part 74 is a glass unit and has no function of coupling out image light, in this embodiment, the maximum side length of the projection of the non-coupling output part 74 on the surface of the first waveguide layer 10 does not exceed the pupil diameter, and the maximum width of the non-coupling output part 74 is less than or equal to 4 mm. It can also be understood that the side length of the projection of the non-coupling output part 74 on the surface of the first waveguide layer 10 is less than or equal to 4 mm, avoiding the problem that the non-coupling output part 74 causes incomplete display of image light. The first coupling device 70 provided by the embodiment of the present application, in which the grating structure and the glass structure alternate, can be fully adapted to the existing Ebeam template and nanoimprint manufacturing processes of the diffractive waveguide layer without introducing any additional processes. As a nano-level precision processing method, for the Ebeam process, it is easy to control the side length of the grid within millimeters. Similarly, for nanoimprinting, there is no essential difference between imprinting a pure grating structure or a structure in which gratings and glass alternate. In this embodiment, the sizes of the first coupling output part 72 and the non-coupling output part 74 can be the same.

[0040] This specification does not limit the specific coupling methods of the first coupling grating 52 and the coupling method of the first coupling device 70. Among them, the first coupling grating 52 can be a transmissive grating for transmissive coupling or a reflective grating for reflective coupling. The first coupling device 70 can be a transmissive grating for transmissive coupling or a reflective grating for reflective coupling.

[0041] Please refer to Figure 2 and Figure 5 , this specification also does not limit the specific positions of the first coupling grating 52 and the first coupling device 70 on the first waveguide layer 10. For example, the first coupling grating 52 and the first coupling device 70 can be arranged on the same side of the first waveguide layer 10, both arranged on the first surface 12 or the second surface 14. When both the first coupling grating 52 and the first coupling device 70 are arranged on the first surface 12, the first coupling grating 52 is a transmissive grating, and the first coupling device 70 is a reflective grating. When both the first coupling grating 52 and the first coupling device 70 are arranged on the second surface 14, the first coupling grating 52 is a reflective grating, and the first coupling device 70 is a transmissive grating. Or, the first coupling grating 52 and the first coupling device 70 can also be arranged on different sides of the first waveguide layer 10. For example, the first coupling grating 52 and the first coupling device 70 are respectively arranged on the first surface 12 and the second surface 14. When the first coupling grating 52 is arranged on the first surface 12, it is a transmissive grating, and when the first coupling grating 52 is arranged on the second surface 14, it is a reflective grating; when the first coupling device 70 is arranged on the first surface 12, it is a reflective grating, and when the first coupling device 70 is arranged on the second surface 14, it is a transmissive grating.

[0042] In this embodiment, the second waveguide layer 30 is disposed on the side of the first waveguide layer 10 away from the light source 201, and the second waveguide layer 30 has an exit surface 31 opposite to the target projection position. The second waveguide layer 30 has opposite third and fourth surfaces 32 and 34, wherein the third surface 32 is disposed opposite to the second surface 14 of the first waveguide layer 10, and the fourth surface 34 is opposite to the target projection position, and the fourth surface 34 is the aforementioned exit surface 31. In this embodiment, the second waveguide layer 30 is integrally in a flat plate shape, so the third surface 32 and the fourth surface 34 can be planes. In other embodiments, the second waveguide layer 30 can be in a curved plate shape, and the third surface 32 and the fourth surface 34 can be a concave surface and a convex surface respectively; the outer shape of the second waveguide layer 30 can be in a circular plate shape, and the third surface 32 and the fourth surface 34 can both be arc-shaped surfaces.

[0043] The second coupling grating 54 is disposed on the surface of the second waveguide layer 30, and is used to change the propagation angle of the second light beam B so that it can meet the propagation condition of total internal reflection in the second waveguide layer 30. This specification does not limit the specific type of the second coupling grating 54. For example, the second coupling grating 54 can include at least one of the following grating structures: a straight grating, a helical grating, a blazed grating, a surface relief grating, and a volume grating. A grating is a dispersion element that uses the interference and diffraction phenomena of light for spectral splitting. In this embodiment, the second waveguide layer 30 also serves as the substrate of the second coupling grating 54, so that the second coupling grating 54 can be attached thereto.

[0044] Please refer to Figure 6 and Figure 7, the second coupling-out device 90 is disposed on the surface of the second waveguide layer 30. The second coupling-out portion 92 of the second coupling-out device 90 is configured to disrupt the propagation of the second light beam B within the second waveguide layer 30 so that the second light beam B can be coupled out to the outside through the exit surface 31 (the fourth surface 34). The second coupling-out device 90 is a glass substrate. In the area corresponding to the glass substrate of the second coupling-out device 90 where a grating structure is provided, a second coupling-out portion 92 is formed; in the area corresponding to the glass substrate of the second coupling-out device 90 where no grating structure is provided, a light-transmitting portion 94 is formed. That is, the light-transmitting portion 94 is a glass unit, and the light-transmitting portion 94 can transmit at least part of the first light beam A coupled out from the first waveguide layer 10. In a specific embodiment, both the number of the light-transmitting portions 94 and the number of the second coupling-out portions 92 are provided with a plurality. The plurality of second coupling-out portions 92 and the plurality of light-transmitting portions 94 are alternately arranged in the first direction X and the second direction Y. The plurality of light-transmitting portions 94 are spaced apart from each other in both the first direction X and the second direction Y. Each light-transmitting portion 94 is adjacent to the light-transmitting portion 94. In this arrangement, the second coupling-out portions 92 and the light-transmitting portions 94 are arranged in an interleaved manner, and the final display uniformity is relatively good. In another specific embodiment, both the number of the second coupling-out portions 92 and the number of the light-transmitting portions 94 are also provided with a plurality. The plurality of second coupling-out portions 92 and the plurality of light-transmitting portions 94 are alternately arranged in the first direction X. The plurality of second coupling-out portions 92 are arranged in sequence in the second direction Y. The plurality of second coupling-out portions 92 are spaced apart from each other in the first direction X and adjacent to each other in the second direction Y. The plurality of light-transmitting portions 94 are spaced apart from each other in the first direction X and adjacent to each other in the second direction Y. This arrangement can also reduce stray light, but the uniformity of the final display effect is slightly worse.

[0045] The second output portion 92 and the light-transmitting portion 94 are both substantially cubic, and the projections of the second output portion 92 and the light-transmitting portion 94 on the surface of the second waveguide layer 30 are in a grid shape. Since the light-transmitting portion 94 is a glass unit and has no function of coupling out image light, in this embodiment, the maximum side length of the projection of the light-transmitting portion 94 on the surface of the second waveguide layer 30 does not exceed the pupil diameter, and the maximum width of the light-transmitting portion 94 is less than or equal to 4 mm. It can also be understood that the side length of the projection of the light-transmitting portion 94 on the surface of the first waveguide layer 30 is less than or equal to 4 mm, avoiding the problem that the light-transmitting portion 94 causes incomplete display of image light. The second output device 90 with an alternating grating structure and glass structure provided in the embodiment of the present application can be fully adapted to the existing Ebeam template and nanoimprint manufacturing processes of the diffraction waveguide layer without introducing any additional processes. As a nano-level precision processing method, for the Ebeam process, the side length of the grid can be easily controlled within millimeters. Similarly, for nanoimprinting, there is no essential difference between imprinting a pure grating structure or an alternating structure of a grating and glass. In this embodiment, the sizes of the first output portion 72, the non-output portion 74, the second output portion 92, and the light-transmitting portion 94 may be the same.

[0046] In some other embodiments, when the second waveguide layer 30 is projected onto the plane where the first waveguide layer 10 is located, the orthographic projection of the second input grating 54 at least partially coincides with the first input grating 52. At this time, part of the first light beam is coupled into the first waveguide layer by the first input grating 52 and propagates, and at the same time, part of the first light beam will pass through the first input grating 52 and be incident on the second input grating 54, generating diffraction on the second input grating 54, thereby generating stray light. The light guide module 100 further includes a baffle 20, and the baffle 20 is disposed opposite to the first input grating 52 or the second input grating 54. As an example, please refer to Figure 8 , the light source 201 and the target projection position are on the same side of the light guide module 100. For example, both are on the side of the first waveguide layer 10 away from the second waveguide layer 30. The baffle 20 can be disposed on the side of the second waveguide layer 30 away from the first waveguide layer 10 and is correspondingly disposed in the stacking direction of the first waveguide layer 10 and the second waveguide layer 30. Therefore, the baffle 20 can block the stray light generated when the first light beam A enters the second waveguide layer 30 at the second input grating 54.

[0047] Please refer to Figure 2 and Figure 5, this specification does not limit the specific coupling methods of the second input grating 54 and the second output device 90. Among them, the second input grating 54 can be a transmissive grating for transmissive coupling or a reflective grating for reflective coupling. The second output device 90 can be a transmissive grating for transmissive output or a reflective grating for reflective output. In this embodiment, the light source 201 and the target projection position are respectively located on both sides of the light guide module 100. The second input grating 54 is a transmissive grating when disposed on the third surface 32, and the second input grating 54 is a reflective grating when disposed on the second surface 14; the first output device 70 is a reflective grating when disposed on the third surface 32, and the first output device 70 is a transmissive grating when disposed on the second surface 14.

[0048] This specification also does not limit the specific positions of the second input grating 54 and the second output device 90 on the second waveguide layer 30. For example, the second input grating 54 and the second output device 90 can be disposed on the same side of the second waveguide layer 30, both on the third surface 32 or the fourth surface 34. Or, the second input grating 54 and the second output device 90 can also be disposed on different sides of the second waveguide layer 30. For example, the second input grating 54 and the second output device 90 are respectively disposed on the third surface 32 and the fourth surface 34.

[0049] This specification does not limit the relative positions of the first input grating 52 and the second input grating 54. For example, the first input grating 52 is disposed on the side of the first waveguide layer 10 facing away from the second waveguide layer 30 (the first surface 12), and the second input grating 54 is disposed on the side of the second waveguide layer 30 facing the first waveguide layer 10 (the third surface 32). Or, the first input grating 52 is disposed on the side of the first waveguide layer 10 facing the second waveguide layer 30, and the second input grating 54 is disposed on the side of the second waveguide layer 30 facing away from the first waveguide layer 10 (the fourth surface 34). Or, the first input grating 52 and the second input grating 54 are respectively disposed on the opposite sides of the first waveguide layer 10 and the second waveguide layer 30 (the first surface 12 and the fourth surface 34). Or, the first input grating 52 and the second input grating 54 are respectively disposed on the opposite sides of the first waveguide layer 10 and the second waveguide layer 30 (the second surface 14 and the third surface 32).

[0050] This specification does not limit the relative positions of the first output device 70 and the second output device 90. For example, the first output device 70 is disposed on the side (the first surface 12) of the first waveguide layer 10 away from the second waveguide layer 30, and the second output device 90 is disposed on the side (the third surface 32) of the second waveguide layer 30 facing the first waveguide layer 10. Alternatively, the first output device 70 is disposed on the side of the first waveguide layer 10 facing the second waveguide layer, and the second output device 90 is disposed on the side (the fourth surface 34) of the second waveguide layer 30 away from the first waveguide layer 10. Alternatively, the first input grating 52 and the second input grating 54 are respectively disposed on the opposite sides (the first surface 12 and the fourth surface 34) of the first waveguide layer 10 and the second waveguide layer 30. Alternatively, preferably, the first output device 70 and the second output device 90 are respectively disposed on the opposite sides (the second surface 14 and the third surface 32) of the first waveguide layer 10 and the second waveguide layer 30 facing each other. At this time, the first output device 70 and the second output device 90 are closest to each other, reducing the possibility that at least part of the first light beam A emitted from the first output device 70 is incident on the second input portion of the second waveguide layer after long-distance propagation, thereby generating stray light. In this embodiment, the first light beam A is blue light, the second light beam B is red light, and the wavelength of the second light beam B is greater than the wavelength of the first light beam A. The first waveguide layer 10 and the second waveguide layer 30 are respectively designed with grating periods for blue light (the first light beam A) and red light (the second light beam B) so that the diffraction angles of the first light beam A and the second light beam A are close, thereby improving color performance. The first waveguide layer 10 and the second waveguide layer 30 are stacked. Projecting the second output device 90 and the first output device 70 onto the second surface 14, the projection of the second output portion 92 coincides with the orthographic projection of the non-output portion 74, and the orthographic projection of the light-transmitting portion 94 coincides with the orthographic projection of the first output portion 72.

[0051] During use, the light source 201 emits the first light beam A and the second light beam B. The first light beam A is coupled into the first waveguide layer 10 through the first input grating 52 and propagates along the light propagation direction defined by the first waveguide layer 10 to the first output device 70, and is output from the first waveguide layer 10 at the first output portion 72. Taking the second output device 90 disposed on the fourth surface 34 as an example, the first light beam A output from the first waveguide layer 10 enters the second waveguide layer 30, passes through the light-transmitting portion 94 corresponding to the first output portion 72, is transmitted out of the second waveguide layer 30 from the light-emitting surface 31, and propagates to the target projection position. The second light beam B is coupled into the second waveguide layer 30 through the second input grating 54 and propagates along the light propagation direction defined by the second waveguide layer 30 to the second output device 90, and is output from the second waveguide layer 30 at the second output portion 92 and propagates to the target projection position.

[0052] The first light beam A (blue light) can be transmitted out of the second waveguide layer 30 from the light-transmitting portion 94 on the second waveguide layer 30, reducing the stray light generated when the first light beam A is coupled out of the second waveguide layer 30, and at the same time improving the phenomenon of the decrease in the image light efficiency caused by the diffraction of the first light beam A in the second waveguide layer 30.

[0053] When the light guide module 100 provided by the embodiment of the present application works, the light source 201 emits the first light beam A and the second light beam B. The first light beam A is coupled into the first waveguide layer 10 through the coupling device 50 and propagates in the first waveguide layer 10 to the first coupling-out device 70. The first light beam A is coupled out of the first waveguide layer 10 through the first coupling-out portion 72. Taking the second waveguide layer 30 located on the side of the first waveguide layer 10 away from the light source 201 as an example, after the first light beam A is coupled out of the first waveguide layer 10 through the first coupling-out portion 72, it is transmitted out of the second waveguide layer 30 through the light-transmitting portion 94 and propagates to the target projection position. The second light beam B is coupled into the second waveguide layer 30 through the coupling device 50 and is conducted in the second waveguide layer 30 to the second coupling-out device 90. The second light beam B is coupled out of the second waveguide layer 30 through the second coupling-out portion 92 and propagates to the target projection position.

[0054] The coupling-out regions (the first coupling-out portion 72 and the second coupling-out portion 94) on the first waveguide layer 10 and the second waveguide layer 30 are staggeredly arranged, so that the first light beam A coupled out of the first waveguide layer 10 will enter the light-transmitting region (the light-transmitting portion 94) of the second waveguide layer 30, and thus directly passes through the second waveguide layer 30 and propagates to the target projection position. The light guide module 100 of the embodiment of the present application avoids the phenomenon of stray light generated when the first light beam A with a different wavelength band from the second light beam B enters the second waveguide layer 30. On the one hand, it reduces the impact on the human eye observation experience, and on the other hand, it improves the image light efficiency of the first light beam A.

[0055] In the description of this specification, the description referring to terms such as "one embodiment", "some embodiments", "example", "specific example", or "some examples" means that the specific features, structures, materials, or characteristics described in connection with the embodiment or example are included in at least one embodiment or example of the present application. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials, or characteristics described can be combined in any one or more embodiments or examples in a suitable manner. In addition, without contradiction, those skilled in the art can combine and combine the different embodiments or examples described in this specification and the features of different embodiments or examples.

[0056] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present application and are not intended to limit them. Although the present application has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that they can still modify the technical solutions described in the foregoing embodiments or perform equivalent replacements for some of the technical features. 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. A light guide module, characterized in that, For conducting the light emitted by a light source to a target projection position, the light source being configured to emit a first light beam and a second light beam, the light guiding module comprising: A first waveguide layer and a second waveguide layer stacked, a first coupling-out device disposed on the first waveguide layer, and a second coupling-out device disposed on the second waveguide layer; The first waveguide layer is configured to transmit the first light beam, the first coupling-out device having an adjacent first coupling-out portion and a non-coupling-out portion, the first coupling-out portion being configured to couple out the first light beam propagating in the first waveguide layer; and The second waveguide layer is configured to transmit the second light beam, the second coupling-out device having an adjacent second coupling-out portion and a light-transmitting portion, the second coupling-out portion being configured to couple out the second light beam propagating in the second waveguide layer to the target projection position, the light-transmitting portion being configured to transmit the first light beam coupled out from the first waveguide layer so that at least part of the first light beam coupled out from the first waveguide layer is emitted to the target projection position.

2. The light guide module according to claim 1, wherein Projecting the second waveguide layer onto the plane where the first waveguide layer is located, the orthographic projection of the second coupling-out portion at least partially coincides with the non-coupling-out portion, and the orthographic projection of the light-transmitting portion at least partially coincides with the first coupling-out portion.

3. The light guide module according to claim 1, wherein The wavelength of the first light beam is in a first wavelength band, the wavelength of the second light beam is in a second wavelength band, the first wavelength band and the second wavelength band are different, the second waveguide layer is configured to be disposed between the target projection position and the first waveguide layer, and the central wavelength of the first wavelength band is less than the central wavelength of the second wavelength band.

4. The light guide module according to any one of claims 1 to 3, characterized in that, The light guiding module further includes a first coupling-in grating and a second coupling-in grating, the first coupling-in grating being located on the surface of the first waveguide layer, the first coupling-in grating being configured to couple the first light beam into the first waveguide layer for propagation, the second coupling-in grating being disposed on the surface of the second waveguide layer, the second coupling-in grating being configured to couple the second light beam into the second waveguide layer for propagation; The first coupling-in grating is disposed on the side of the first waveguide layer facing away from the second waveguide layer, and the second coupling-in grating is disposed on the side of the second waveguide layer facing the first waveguide layer; or The first coupling-in grating is disposed on the side of the first waveguide layer facing the second waveguide layer, and the second coupling-in grating is disposed on the side of the second waveguide layer facing away from the first waveguide layer; or The first coupling-in grating and the second coupling-in grating are respectively disposed on the opposite sides of the first waveguide layer and the second waveguide layer; or The first coupling-in grating and the second coupling-in grating are respectively disposed on the opposite sides of the first waveguide layer and the second waveguide layer facing each other.

5. The light guide module according to claim 4, wherein Projecting the second waveguide layer onto the plane where the first waveguide layer is located, the orthographic projection of the second coupling-in grating at least partially coincides with the first coupling-in grating, and the light guiding module further includes a baffle, the baffle being disposed opposite to the first coupling-in grating or the second coupling-in grating.

6. The light guiding module according to any one of claims 1-3, wherein The first coupling-out device is disposed on a side of the first waveguide layer facing away from the second waveguide layer, and the second coupling-out device is disposed on a side of the second waveguide layer facing the first waveguide layer; or The first coupling-out device is disposed on a side of the first waveguide layer facing the second waveguide layer, and the second coupling-out device is disposed on a side of the second waveguide layer facing away from the first waveguide layer; or The first coupling-out device and the second coupling-out device are respectively disposed on opposite sides of the first waveguide layer and the second waveguide layer; or The first coupling-out device and the second coupling-out device are respectively disposed on opposite sides of the first waveguide layer and the second waveguide layer facing each other.

7. The light guide module according to any one of claims 1-3, characterized in that The number of the first coupling-out portions and the number of the non-coupling-out portions are both provided with a plurality. The plurality of first coupling-out portions and the plurality of non-coupling-out portions are alternately arranged in a first direction and a second direction; the number of the second coupling-out portions and the number of the light-transmitting portions are both provided with a plurality. The plurality of second coupling-out portions and the plurality of light-transmitting portions are alternately arranged in the first direction and the second direction; the first direction and the second direction intersect.

8. The light guide module according to claim 1, wherein The sizes of the first coupling-out portion, the non-coupling-out portion, the second coupling-out portion, and the light-transmitting portion are the same, and the maximum width of the non-coupling-out portion is less than or equal to 4 mm.

9. The light guide module according to claim 1, wherein Both the first waveguide layer and the second waveguide layer are glass substrates; A region with a grating structure is formed in the range of the glass substrate corresponding to the first coupling-out device to form the first coupling-out portion; a region without a grating structure in the range of the glass substrate corresponding to the first coupling-out device forms the non-coupling-out portion; A region with a grating structure is formed in the range of the glass substrate corresponding to the second coupling-out device to form the second coupling-out portion; a region without a grating structure in the range of the glass substrate corresponding to the second coupling-out device forms the light-transmitting portion.

10. A head-up display system, characterized in that, Comprising: A light source for emitting a first light beam and a second light beam; The light guide module according to any one of claims 1 to 9, disposed on the light-emitting optical path of the light source for conducting at least part of the first light beam and the second light beam to a target projection position; And A windshield, where the target projection position is located on the windshield, and the windshield is configured to reflect at least part of the first light beam and the second light beam to a human eye observation position.

Images