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 light splitting module and a waveguide module. The light splitting module is used for splitting a light source light beam into a first light beam and a second light beam with different light paths, and guiding the first light beam and the second light beam to the waveguide module. The waveguide module comprises a first waveguide layer, a second waveguide layer, two first coupling devices and a second coupling device, wherein the first waveguide layer and the second waveguide layer are stacked. The two first coupling-in devices comprise a first coupling-in part arranged on the first waveguide layer and a second coupling-in part arranged on the second waveguide layer, and the first coupling-in part and the second coupling-in part are located on the light path of the first light beam so as to be used for coupling in the first light beam. The second coupling-in device is arranged on the second waveguide layer and located on the light path of the second light beam. The second coupling-in device is used for coupling the second light beam into the second waveguide layer. According to the light guide module, the color uniformity of the image is improved.

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 method for drivers to obtain information about the driving vehicle. They can project driving condition and road condition information in real time in the normal driving 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 a 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 cause a decrease in the image light efficiency, thereby deteriorating the image color performance. 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, an embodiment of the present application provides 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 light source beam. The light guide module includes a beam splitting module and a waveguide module. The beam splitting module is used to split the light source beam into a first beam and a second beam with different optical paths and guide the first beam and the second beam to the waveguide module. The waveguide module includes a first waveguide layer and a second waveguide layer stacked, two first coupling devices, and a second coupling device. The two first coupling devices include a first coupling portion disposed on the first waveguide layer and a second coupling portion disposed on the second waveguide layer. The first coupling portion and the second coupling portion are both located on the optical path of the first beam for coupling the first beam. The second coupling device is disposed on the second waveguide layer and located on the optical path of the second beam, and the second coupling device is used to couple the second beam into the second waveguide layer.

[0006] In some alternative embodiments, the first waveguide layer is located between the beam splitting module and the second waveguide layer. Projecting the second waveguide layer onto the plane where the first waveguide layer is located, at least a part of the orthographic projection of the second coupling portion coincides with the first coupling portion, and the orthographic projection of the second coupling device does not coincide with the first coupling portion.

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

[0008] In some alternative embodiments, the light guiding module further includes a first output grating and a second output grating. The first output grating is disposed on the first waveguide layer and is configured to couple out a first light beam from the first waveguide layer. The second output grating is disposed on the second waveguide layer and is configured to couple out the first light beam and the second light beam propagating in the second waveguide layer from the second waveguide layer.

[0009] In some alternative embodiments, the first output grating is disposed on a side of the first waveguide layer facing away from the second waveguide layer, and the second output grating is disposed on a side of the second waveguide layer facing the first waveguide layer; or the first output grating is disposed on a side of the first waveguide layer facing the second waveguide layer, and the second output grating is disposed on a side of the second waveguide layer facing away from the first waveguide layer; or the first output grating and the second output grating are respectively disposed on opposite sides of the first waveguide layer and the second waveguide layer; or the first output grating and the second output grating are respectively disposed on opposite sides of the first waveguide layer and the second waveguide layer facing each other.

[0010] In some alternative embodiments, when the second waveguide layer is projected onto the plane where the first waveguide layer is located, at least a part of the orthographic projection of the second coupling device coincides with the first coupling portion. The light guiding module further includes a baffle, and the baffle is disposed opposite to the first coupling device or / and the second coupling device.

[0011] In some alternative embodiments, the first waveguide layer includes a first surface and a second surface facing away from each other, and the second waveguide layer includes a third surface and a fourth surface facing away from each other; the first coupling portion is disposed on the first surface or the second surface, and both the second coupling portion and the second coupling device are disposed on the third surface or the fourth surface; or the first waveguide layer includes a first surface and a second surface facing away from each other, and the second waveguide layer includes a third surface and a fourth surface facing away from each other; the first coupling portion is disposed on the first surface or the second surface, and the second coupling portion and the second coupling device are respectively disposed on the third surface and the fourth surface.

[0012] In some alternative embodiments, the beam splitting module includes a transmissive-reflective element and a reflective element. The transmissive-reflective element is disposed on the optical path of the light beam of the light source. The transmissive-reflective element is configured to transmit the light beam in the first wavelength band in the light beam of the light source to form a first light beam and to reflect the light beam in the second wavelength band in the light beam of the light source to form a second light beam. The reflective element is located on the optical path of the second light beam to the waveguide module.

[0013] In some alternative embodiments, the first light beam includes red light and green light, and the second light beam includes blue light.

[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 light guide modules, and a windshield. The light source is configured to emit a light source 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 beam and the second beam to a target projection position, which is located on the windshield. The windshield is configured to reflect at least part of the first beam and the second beam to a human eye observation position.

[0015] Compared with the prior art, when the light guide module provided in the embodiment of the present application works, the light source emits a light source beam. The light source beam is divided by a beam splitting module into a first beam and a second beam with different optical paths and is guided to the waveguide module. The first beam is coupled into the first waveguide layer through the first coupling portion and into the second waveguide layer through the second coupling portion, and then is coupled out from the first waveguide layer and the second waveguide layer respectively and conducted to the target projection position. The beam splitting module guides the second beam to be incident on the second coupling device on the second waveguide layer. The second beam is coupled into the second waveguide layer through the second coupling device and is coupled out to the target projection position after propagating in the second waveguide layer. The light guide module of the embodiment of the present application separates the first beam and the second beam through the beam splitting module and guides them to different coupling regions (the first coupling device and the second coupling device) respectively, avoiding the phenomenon of stray light generated when the second beam passes through the first waveguide layer. 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 beam, thereby enhancing the color uniformity of the image. 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 embodiments 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 It is a simplified structural schematic diagram of a vehicle provided by an embodiment of the present application.

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

[0019] Figure 3 is Figure 2 a simplified plan view of the head-up display system shown.

[0020] Figure 4 is Figure 2 a structural schematic diagram of another embodiment of the light guide module shown.

[0021] Reference numeral description: 100, light guide module; 10, beam splitting module; 12, transmissive and reflective element; 14, reflector; 20, baffle; 30, waveguide module; 32, first waveguide layer; 321, first surface; 323, second surface; 34, second waveguide layer; 341, third surface; 343, fourth surface; 36, first coupling-in device; 361, first coupling-in portion; 363, second coupling-in portion; 38, second coupling-in device; 52, first coupling-out grating; 54, second coupling-out grating; 200, head-up display system; 201, light source; 203, windshield; 300, vehicle; 301, vehicle body. Detailed implementation manners

[0022] To enable those skilled in the art to better understand the solutions of this application, the technical solutions in the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings in the embodiments of this application. Obviously, the described embodiments are only some of the embodiments of this application, rather than all the embodiments. Based on the embodiments in this application, all other embodiments obtained by those skilled in the art without creative efforts shall fall within the scope of protection of this application.

[0023] As certain terms are used in the specification and claims to refer to specific components, those skilled in the art should understand that hardware manufacturers may use different nouns to refer to the same component. The specification and claims do not distinguish components by the difference in names, but by the difference in functions of the components. As the term "comprising" mentioned throughout the specification and claims is an open term, it should be interpreted as "including but not limited to"; "substantially" means that those skilled in the art can solve technical problems within a certain error range and basically achieve technical effects.

[0024] Please refer to Figure 1 and Figure 2 , the embodiments of this application provide a head-up display system 200. The head-up display system 200 can be applied to a vehicle 300 and is used to project real-time vehicle condition information, road condition information, etc. of the vehicle 300 in the line of sight direction of the driver during normal driving, improving the safety and comfort of driving. Among them, the "line of sight direction of the driver during normal driving" generally refers to the front windshield of the vehicle 300 opposite to the cab, or the side window glass. This application will take the former as an example for elaboration.

[0025] The vehicle 300 includes a vehicle body 301 and a head-up display system 200 connected to the vehicle body 301. This specification does not limit the specific installation position of the head-up display system 200 inside the vehicle body 301. For example, the head-up display system 200 can be installed on the ceiling of the vehicle 300 or can be provided on the instrument panel of the vehicle 300.

[0026] In this embodiment, the head-up display system 200 may include a light source 201, a light guide module 100, and a windshield 203. Among them, the light source 201 may be an image display, which is used to display an image source (such as for displaying multimedia content such as images), and emits image source light rays carrying image information. In this embodiment, the light source 201 is used to emit a light source beam (image source light rays). The windshield 203 is the front windshield of the vehicle 300. The windshield 203 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 203 and the vehicle body 301. The head-up display system 200 is disposed inside the vehicle body 301, and is used to project vehicle condition information and road condition information of the vehicle 300 onto the windshield 203, and the information projected by the head-up display system 200 is in the normal driving line of sight direction of the driver. The windshield 203 is used to reflect at least part of the light source beam to the human eye observation position.

[0027] The light guide module 100 is disposed on one side of the light source 201, and the light guide module 100 is located on the optical path of the light source beam emitted by the light source 201. The light guide module 100 is used to conduct at least part of the light source beam to the target projection position. The light source 201 emits image source light rays, and the light rays are conducted by the light guide module 100 and at least partially propagate to the target projection position, and are reflected by the windshield 203 to form an image and enter the human eye. Among them, the "target projection position" may be the position of the windshield 203 in the normal driving line of sight direction of the driver. When the head-up display system 200 is applied to other scenarios, the target projection position is defined according to the actual scenario. The target projection position (windshield 203) and the light source 201 may be respectively located on opposite sides of the light guide module 100, or the target projection position (windshield 203) and the light source 201 may also be both located on the same side of the light guide module 100.

[0028] The light guide module 100 may include a beam splitting module 10 and a waveguide module 30. The beam splitting module 10 is used to split the light source beam into a first beam A and a second beam B with different optical paths, and guide the first beam A and the second beam B to the waveguide module 30. The waveguide module 30 may include a first waveguide layer 32, a second waveguide layer 34, a first coupling device 36, and a second coupling device 38. The first waveguide layer 32 and the second waveguide layer 34 are stacked. The number of the first coupling devices 36 is set to two. The two first coupling devices 36 include a first coupling portion 361 disposed on the first waveguide layer 32 and a second coupling portion 363 disposed on the second waveguide layer 34. Both the first coupling portion 361 and the second coupling portion 363 are located on the optical path of the first beam A for coupling the first beam A. The second coupling device 38 is disposed on the second waveguide layer 34 and is located on the optical path of the second beam B. The second coupling device 38 is used to couple the second beam B into the second waveguide layer 34.

[0029] During operation, the light source 201 emits a light source beam. The light source beam is split by the beam splitting module 10 into a first beam A and a second beam B with different optical paths and is guided to the waveguide module 30. The first beam A is coupled into the first waveguide layer 32 through the first coupling portion 361, and is coupled into the second waveguide layer 34 through the second coupling portion 363, and then is coupled out from the first waveguide layer 32 and the second waveguide layer 34 respectively and conducted to the target projection position. The beam splitting module 10 deflects the second beam B so that it bypasses the first coupling portion 361 and is incident on the second coupling device 38 on the second waveguide layer 34. The second beam B is coupled into the second waveguide layer 34 through the second coupling device 38, propagates in the second waveguide layer 34, and then is coupled out to the target projection position. The light guiding module 100 according to the embodiment of the present application separates the first beam A and the second beam B through the beam splitting module 10, and guides them to different coupling regions (the first coupling device 36 and the second coupling device 38) respectively, avoiding the phenomenon of stray light generated when the second beam B passes through the first waveguide layer 32. 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 beam A, thereby improving the color uniformity of the image.

[0030] In this embodiment, both the first waveguide layer 32 and the second waveguide layer 34 are guiding structures for transmitting optical frequency electromagnetic waves composed of a light-transparent medium (such as quartz glass), and are devices for guiding waves to propagate therein. They are used to limit the propagation path of the light beam in space. When the propagation angle of the light beam satisfies the total reflection condition, it can only propagate within the waveguide layer. The present specification does not limit the specific types of the first waveguide layer 32 and the second waveguide layer 34. Both the first waveguide layer 32 and the second waveguide layer 34 can be made into very thin and light flat glass forms. In this embodiment, the first waveguide layer 32 and the second waveguide layer 34 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 angle range in which total reflection can occur in the first waveguide layer 32 and the second waveguide layer 34 increases, increasing the design freedom.

[0031] The present specification does not limit the specific position of the first waveguide layer 32. For example, the first waveguide layer 32 can be disposed between the beam splitting module 10 and the second waveguide layer 34, or the first waveguide layer 32 can be disposed on the side of the second waveguide layer 34 away from the beam splitting module 10. In this embodiment, the first waveguide layer 32 is disposed between the beam splitting module 10 and the second waveguide layer 34. Both the first coupling portion 361 and the second coupling portion 363 are located on the optical path of the first beam A. The first beam A can be coupled into the first waveguide layer 32 through the first coupling portion 361 and coupled into the second waveguide layer 34 through the second coupling portion 363.

[0032] In this embodiment, the wavelength of the first light beam A is in the first band, and the wavelength of the second light beam B is in the second band, and the first band and the second band are different. This specification does not limit the specific number of light sources 201. For example, the number of light sources 201 can 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 emission directions of the first light beam A and the second light beam B can be the same. Or, the number of light sources 201 can also be set to two. If the two light sources 201 are arranged on opposite sides of the light guide module 100, the emission directions of the first light beam A and the second light beam B are different. In this embodiment, the number of light sources 201 is set to one, and the light source 201 is located on the side of the light guide module 100 away from the target projection position. The first light beam A and the second light beam B are image lights 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 can be a red light image light, and the second light beam B can be a blue light image light; or, the first light beam A can be a blue light image light, and the second light beam B can be a red light image light.

[0033] Please refer to Figure 2 and Figure 3 simultaneously. In this embodiment, the central wavelength of the first band is greater than the central wavelength of the second band, and the second waveguide layer 34 is used to be arranged between the target projection position and the first waveguide layer 32. The first waveguide layer 32 may include a first surface 321 and a second surface 323, and the first surface 321 and the second surface 323 face away from each other. Among them, the first surface 321 faces the light source 201, and the first surface 321 serves as the incident surface of the first waveguide layer 32. In this embodiment, the first waveguide layer 32 is integrally presented as a flat plate, so the first surface 321 and the second surface 323 can be planes. In other embodiments, the first waveguide layer 32 can be presented as a curved plate, and the first surface 321 and the second surface 323 can be a concave surface and a convex surface respectively; the outer shape of the first waveguide layer 32 can be presented as a circular plate, and the first surface 321 and the second surface 323 can both be arc surfaces.

[0034] The first coupling-in part 361 is disposed on the first surface 321 or the second surface 323. The first surface 321 faces the light source 201. If the first coupling-in part 361 is disposed on the first surface 321, the first coupling-in part 361 can be a grating for transmissive coupling-in; if the first coupling-in part 361 is disposed on the second surface 323, the first coupling-in part 361 can be a grating for reflective coupling-in. The first coupling-in part 361 is used to change the propagation angle of the first light beam A so that it can meet the propagation condition of total internal reflection in the first waveguide layer 32. This specification does not limit the specific type of the first coupling-in part 361. For example, the first coupling-in part 361 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. In this embodiment, the first waveguide layer 32 also serves as the substrate of the first coupling-in part 361, enabling the first coupling-in part 361 to be attached thereto.

[0035] In this embodiment, the light guiding module 100 may further include an output device. The output device may include a first output grating 52 and a second output grating 54, and the first output grating 52 and the second output grating 54 are respectively disposed on the surfaces of the first waveguide layer 32 and the second waveguide layer 34. Among them, the first output grating 52 is disposed on the surface of the first waveguide layer 32, and it is used to disrupt the propagation of the first light beam A in the first waveguide layer 32 so that the first light beam A can be output to the outside. This specification does not limit the specific type of the first output grating 52. For example, the first output grating 52 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 performs spectral splitting by using the interference and diffraction phenomena of light. In this embodiment, the first waveguide layer 32 also serves as the substrate of the first output grating 52, enabling the first output grating 52 to be attached thereto.

[0036] The first output grating 52 is disposed on the surface of the first waveguide layer 32. For example, the first output grating 52 can be disposed on the first surface 321 or the second surface 323. The first surface 321 faces the light source 201. If the first output grating 52 is disposed on the first surface 321, the first output grating 52 can be a grating for reflective output; if the first output grating 52 is disposed on the second surface 323, the first output grating 52 can be a grating for transmissive output. This specification does not limit the relative positions of the first coupling-in part 361 and the first output grating 52 on the first waveguide layer 32 either. For example, the first coupling-in part 361 and the first output grating 52 can be disposed on the same side of the first waveguide layer 32, both on the first surface 321 or the second surface 323. Alternatively, the first coupling-in part 361 and the first output grating 52 can also be disposed on different sides of the first waveguide layer 32, that is, respectively disposed on the first surface 321 and the second surface 323.

[0037] In this embodiment, the second waveguide layer 34 is disposed on a side of the first waveguide layer 32 away from the light source 201, and the second waveguide layer 34 has an exit surface opposite to the target projection position. The second waveguide layer 34 has opposite third surface 341 and fourth surface 343. Among them, the third surface 341 is disposed opposite to the second surface 323 of the first waveguide layer 32, and the fourth surface 343 is opposite to the target projection position, and the fourth surface 343 is the exit surface of the second waveguide layer 34. In this embodiment, the second waveguide layer 34 is integrally presented as a flat plate, so the third surface 341 and the fourth surface 343 can be planes. In other embodiments, the second waveguide layer 34 can be presented as a curved plate, and the third surface 341 and the fourth surface 343 can be a concave surface and a convex surface respectively; the outer shape of the second waveguide layer 34 can be presented as a circular plate, and the third surface 341 and the fourth surface 343 can both be arc surfaces.

[0038] Both the second coupling portion 363 and the second coupling device 38 are disposed on the surface of the second waveguide layer 34. The second coupling portion 363 is used to change the propagation angle of the first light beam A so that it can meet the propagation condition of total internal reflection in the second waveguide layer 34; the second coupling device 38 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 34. This specification does not limit the specific types of the second coupling portion 363 and the second coupling device 38. For example, both the second coupling portion 363 and the second coupling device 38 can include at least one of the following grating structures: straight grating, helical grating, blazed grating, surface relief grating, volume grating. In this embodiment, the second waveguide layer 34 also serves as a substrate for the second coupling portion 363 and the second coupling device 38, so that the second coupling portion 363 and the second coupling device 38 can be attached thereto.

[0039] In this embodiment, the second coupling portion 363 can be disposed on the third surface 341 and the fourth surface 343. If the second coupling portion 363 is disposed on the third surface 341, the second coupling portion 363 can be a transmissive coupling grating; if the second coupling portion 363 is disposed on the fourth surface 343, the second coupling portion 363 can be a reflective coupling grating. The second coupling device 38 can be disposed on the third surface 341 and the fourth surface 343. If the second coupling device 38 is disposed on the third surface 341, the second coupling device 38 can be a transmissive coupling grating; if the second coupling device 38 is disposed on the fourth surface 343, the second coupling device 38 can be a reflective coupling grating.

[0040] This specification also places no restrictions on the relative positions of the second coupling portion 363 and the second coupling device 38 on the second waveguide layer 34. For example, the second coupling portion 363 and the second coupling device 38 can be disposed on the same side of the second waveguide layer 34, both on the third surface 341 or the fourth surface 343. Alternatively, the second coupling portion 363 and the second coupling device 38 can also be disposed on different sides of the second waveguide layer 34, that is, respectively on the third surface 341 and the fourth surface 343. If the second coupling portion 363 and the second coupling device 38 are disposed on the same side of the second waveguide layer 34, the second coupling portion 363 and the second coupling device 38 can be arranged side by side, and there can be a gap between the two.

[0041] Project the second waveguide layer 34 onto the plane where the first waveguide layer 32 is located. The orthographic projection of the second coupling portion 363 at least partially coincides with the first coupling portion 361, and the orthographic projection of the second coupling device 38 does not coincide with the first coupling portion 361. Since the orthographic projection of the second coupling device 38 does not coincide with the first coupling portion 361, the light path of the second light beam A reaching the second coupling device 38 under the guidance of the light splitting module 10 will not pass through the first coupling portion 361, thereby avoiding the phenomenon of stray light generated when passing through the first waveguide layer 32.

[0042] In some other embodiments, project the second waveguide layer 34 onto the plane where the first waveguide layer 32 is located. The orthographic projection of the second coupling device 38 at least partially coincides with the first coupling portion 361. The light guiding module 100 further includes a baffle 20, and the baffle 20 is disposed opposite to the first coupling device 36 or the second coupling device 38. As an example, please refer to Figure 4 , the light source 201 and the target projection position are located on the same side of the light guiding module 100. For example, both are located on the side of the first waveguide layer 32 facing away from the second waveguide layer 34. The baffle 20 can be disposed on the side of the second waveguide layer 34 facing away from the first waveguide layer 32, and is correspondingly disposed in the stacking direction of the first waveguide layer 32 and the second waveguide layer 34 with the second coupling grating 54. Since the light source 201 and the target projection position are located on the same side of the light guiding module 100, the first light beam A can be coupled out to the target projection position without passing through the second waveguide layer 34, and the baffle 20 can block the stray light generated when the first light beam A enters the second waveguide layer 34 at the second coupling grating 54.

[0043] Please refer to again Figure 2 and Figure 3, in this embodiment, the second output grating 54 is disposed on the surface of the second waveguide layer 34, and the second output grating 54 is configured to couple out the first light beam A and the second light beam B propagating in the second waveguide layer 34 from the second waveguide layer 34. The second output grating 54 may be disposed on the third surface 341 or the fourth surface 343. This specification does not limit the relative positions between the second output grating 54 and the first output grating 52. The first output grating 52 is disposed on the side of the first waveguide layer 32 facing away from the second waveguide layer 34 (the first surface 321), and the second output grating 54 is disposed on the side of the second waveguide layer 34 facing the first waveguide layer 32 (the third surface 341); or the first output grating 52 is disposed on the side of the first waveguide layer 32 facing the second waveguide layer 34 (the second surface 323), and the second output grating 54 is disposed on the side of the second waveguide layer 34 facing away from the first waveguide layer 32 (the fourth surface 343); or the first output grating 52 and the second output grating 54 are respectively disposed on the opposite sides of the first waveguide layer 32 and the second waveguide layer 34 (the first surface 321 and the fourth surface 343); or the first output grating 52 and the second output grating 54 are respectively disposed on the facing sides of the first waveguide layer 32 and the second waveguide layer 34 (the second surface 323 and the third surface 341).

[0044] In this embodiment, the first light beam A includes a red light image light and a green light image light, the second light beam B includes a blue light image light, and the wavelength of the second light beam B is less than the wavelength of the first light beam A. The first coupling portion 361 and the second coupling portion 363 are both red and green light coupling gratings, and the second coupling device 38 is a blue light coupling grating. Projecting the second waveguide layer 34 onto the plane where the first waveguide layer 32 is located, the orthographic projection of the second coupling portion 363 at least partially coincides with the first coupling portion 361, and the orthographic projection of the second coupling device 38 does not coincide with the first coupling portion 361. The projection of the blue light coupling grating (the second coupling device 38) and the red and green light coupling grating (the second coupling portion 363) are arranged with a displacement. And the first waveguide layer 32 is close to the light source 201, and the second light beam B is offset by the beam splitting module 10 so that it bypasses the red and green light coupling grating (the second coupling portion 363) and is incident on the red and green light coupling grating (the second coupling portion 363). The second light beam B exits from the coupling area of the second waveguide layer 34, is reflected by the windshield 203, and then enters the human eye.

[0045] The beam splitting module 10 is disposed between the light source 201 and the first waveguide layer 32. It is used to split the light source beam into a first beam A and a second beam A with different optical paths, and guide the first beam A and the second beam B to the waveguide module 30. The beam splitting module 10 may include a transmissive-reflective element 12 and a reflective element 14. The transmissive-reflective element 12 is disposed on the optical path of the light source beam. The transmissive-reflective element 12 is used to transmit the beam of the first wavelength band in the light source beam to form the first beam A, and is used to reflect the beam of the second wavelength band in the light source beam to form the second beam B. The reflective element 14 is located on the optical path from the second beam B to the waveguide module 30.

[0046] The transmissive-reflective element 12 is used to transmit the red and green image light (the first beam A) in the light source beam to the first coupling portion 361 of the first waveguide layer 32. The transmissive-reflective element 12 is also used to reflect the blue image light (the second beam B) in the light source beam to the reflective element 14. This specification does not limit the specific type of the transmissive-reflective element 12. For example, the transmissive-reflective element 12 may be a beam splitter or a filter. The reflective element 14 is disposed on the optical path of the second beam B reflected by the transmissive-reflective element 12. The reflective element 14 is used to reflect the second beam B to the second coupling device 38 on the second waveguide layer 34. This specification does not limit the specific type of the reflective element 14. For example, the reflective element 14 may be a mirror, a reflective film, a reflective grating, etc. Since the field of view angle of the image light in the application scenario of the head-up display system 200 is small, the degree of diffusion of the light spot during the propagation process before entering the coupling region of the light guiding module 100 is not large, that is, there is no need to use the transmissive-reflective element 12 and the reflective element 14 with too large sizes.

[0047] When the light guiding module 100 provided by the embodiment of the present application works, the light source 201 emits a light source beam. The light source beam is split by the beam splitting module 10 into a first beam A and a second beam B with different optical paths and is guided to the waveguide module 30. The first beam A is coupled into the first waveguide layer 32 through the first coupling portion 361 and is coupled into the second waveguide layer 34 through the second coupling portion 363, and then is respectively coupled out from the first waveguide layer 32 and the second waveguide layer 34 and conducted to the target projection position. The beam splitting module 10 deflects the second beam B so that it bypasses the first coupling portion 361 and is incident on the second coupling device 38 on the second waveguide layer 34. The second beam B is coupled into the second waveguide layer 34 through the second coupling device 38, propagates in the second waveguide layer 34, and then is coupled out to the target projection position. The light guiding module 100 of the embodiment of the present application separates the first beam A and the second beam B through the beam splitting module 10 and respectively guides them to different coupling regions (the first coupling device 36 and the second coupling device 38), avoiding the phenomenon of stray light generated when the second beam B passes through the first waveguide layer 32. 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 beam A, thereby improving the color uniformity of the image.

[0048] In the description of this specification, the descriptions referring to terms such as "one embodiment", "some embodiments", "examples", "specific examples", or "some examples", etc. mean 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 this application. In this specification, the schematic expressions 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 a suitable manner in any one or more embodiments or examples. 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.

[0049] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of this application, not to limit them. Although this 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 recorded in the foregoing embodiments, or perform equivalent replacements for some of the technical features. And 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 various embodiments of this 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 is used to emit a light source beam, and the light guiding module includes a beam splitting module and a waveguide module; The beam splitting module is used to split the light source beam into a first beam and a second beam with different optical paths, and guide the first beam and the second beam to the waveguide module; The waveguide module includes: A first waveguide layer and a second waveguide layer stacked; Two first coupling devices, the two first coupling devices include a first coupling portion disposed on the first waveguide layer and a second coupling portion disposed on the second waveguide layer, and both the first coupling portion and the second coupling portion are located on the optical path of the first beam for coupling the first beam; and A second coupling device, disposed on the second waveguide layer and located on the optical path of the second beam, the second coupling device is used to couple the second beam into the second waveguide layer.

2. The light guide module according to claim 1, wherein The first waveguide layer is located between the beam splitting module and the second waveguide layer. Projecting the second waveguide layer onto the plane where the first waveguide layer is located, the orthographic projection of the second coupling portion at least partially coincides with the first coupling portion, and the orthographic projection of the second coupling device does not coincide with the first coupling portion.

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

4. The light guide module according to any one of claims 1-3, characterized in that, The light guiding module further includes a first output grating and a second output grating. The first output grating is disposed on the first waveguide layer, and the first output grating is used to couple out the first beam from the first waveguide layer; the second output grating is disposed on the second waveguide layer, and the second output grating is used to couple out the first beam and the second beam propagating in the second waveguide layer from the second waveguide layer.

5. The light guiding module according to claim 4, wherein The first output grating is disposed on the side of the first waveguide layer facing away from the second waveguide layer, and the second output grating is disposed on the side of the second waveguide layer facing the first waveguide layer; or The first output grating is disposed on the side of the first waveguide layer facing the second waveguide layer, and the second output grating is disposed on the side of the second waveguide layer facing away from the first waveguide layer; or The first output grating and the second output grating are respectively disposed on the opposite sides of the first waveguide layer and the second waveguide layer; or The first output grating and the second output grating are respectively disposed on the opposite sides of the first waveguide layer and the second waveguide layer facing each other.

6. 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 device at least partially coincides with the first coupling portion, and the light guiding module further includes a baffle, and the baffle is disposed opposite to the first coupling device or / and the second coupling device.

7. The light guiding module according to any one of claims 1-3, wherein The first waveguide layer includes a first surface and a second surface facing away from each other, and the second waveguide layer includes a third surface and a fourth surface facing away from each other; the first coupling portion is disposed on the first surface or the second surface, and the second coupling portion and the second coupling device are both disposed on the third surface or the fourth surface; or The first waveguide layer includes a first surface and a second surface facing away from each other, and the second waveguide layer includes a third surface and a fourth surface facing away from each other; the first coupling portion is disposed on the first surface or the second surface, and the second coupling portion and the second coupling device are respectively disposed on the third surface and the fourth surface.

8. The light guide module according to claim 3, characterized in that, The light splitting module includes a transmissive-reflective member and a reflective member. The transmissive-reflective member is disposed on the optical path of the light beam of the light source. The transmissive-reflective member is configured to transmit the light beam of the first wavelength band in the light beam of the light source to form the first light beam, and to reflect the light beam of the second wavelength band in the light beam of the light source to form the second light beam. The reflective member is located on the optical path from the second light beam to the waveguide module.

9. The light guide module according to claim 3, wherein, The first light beam includes red light and green light, and the second light beam includes blue light.

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

Images