TWI827004B - Head-up displays and vehicles - Google Patents

Abstract

Embodiments of the present application provide a head-up display (HUD) and a vehicle. The HUD includes an image source, a polarization beam splitting element, a polarization conversion element, and a reflection component. The image source is used to emit circularly polarized light. The polarization beam splitter is used to reflect S-state polarized light in circularly polarized light and transmit P-state polarized light in circularly polarized light. The S-state polarized light reflected by the polarization beam splitting element is defined as a first image light. The polarization conversion element is used to convert P-state polarized light into S-state polarized light. The S-state polarized light converted by the polarization conversion element is defined as a second image light. The reflection component is used to reflect the first image light and the second image light to a projection medium to form a first virtual image and a second virtual image, respectively. Virtual image distances and viewing angles of the first virtual image and the second virtual image are different, respectively.

Description

Heads-up displays and vehicles

The present application relates to the field of display technology, specifically, to a head-up display and a vehicle.

The conventional head-up display has only a single virtual image distance and a single field of view. However, with the development of head-up displays, a single virtual image distance and a single field of view can no longer meet driving needs.

A first aspect of this application provides a head-up display. The head-up display includes: an image source, the image source is used to emit image light, the image light is circularly polarized light; a polarizing light splitting element, the polarizing light splitting element is located on the light exit side of the image source, for Reflecting the S-state polarized light in the circularly polarized light to initiate a first optical path, and transmitting the P-state polarized light in the circularly polarized light to initiate a second optical path, wherein the reflection of the polarization splitting element is defined S-state polarized light is the first image light; Polarization conversion element, the polarization conversion element is located on the second optical path and is used to convert the P-state polarized light into S-state polarized light, wherein the S-state polarized light converted by the polarization conversion element is defined as the third two image lights; and a reflective component located on the first optical path and the second optical path for reflecting the first image light and the second image light to the projection medium to respectively form the first A virtual image and a second virtual image, wherein the first virtual image and the second virtual image have different virtual image distances and different viewing angles.

The head-up display is configured with a polarizing beam splitting element to divide the image light into P-state polarized light and S-state polarized light propagating in different optical paths, wherein the S-state polarized light reflected by the polarizing beam splitting element serves as the first image light. The P-state polarized light transmitted by the polarization splitting element is converted into S-state polarized light through the polarization conversion element as the second image light. After the first image light and the second image light are reflected to the projection medium by the reflective component, virtual images with two virtual image distances and two field of view angles are simultaneously generated, which helps to improve driving safety.

A second aspect of this application provides a vehicle, which includes: a windshield; and the head-up display described in the first aspect; wherein the windshield is the projection medium.

The vehicle includes the head-up display of the first aspect, so it has at least the same advantages as the head-up display of the first aspect, which will not be described again.

100: Head-up display

10:Image source

11:Laser light source

111:Red laser

112:Green laser

113:Blue laser

12: Bundle components

13:MEMS micro-mirror

20:Polarization splitting element

30:Reflector

40:Polarization conversion element

51: First diffusion element

52: Second diffusion element

60: Reflective component

61:First freeform mirror

62: Second freeform mirror

VI1: The first virtual image

VI2: Second virtual image

200:windshield

S: S-state polarized light

P:P state polarized light

VID1, VID2: virtual image distance

HFOV1: first horizontal field of view

VFOV1: first vertical field of view

HFOV2: Second horizontal field of view

VFOV2: Second vertical field of view

α:tilt angle

Figure 1 is a schematic structural diagram of a head-up display according to an embodiment of the present application.

Figure 2 is a schematic diagram showing the relationship between the reflectivity of P-state polarized light and S-state polarized light and the tilt angle of the windshield.

Figure 3 is a schematic structural diagram of the image source in Figure 1.

Head-up display (HUD) technology, also known as head-up display technology, has been increasingly widely used in the automotive, aerospace, and navigation fields in recent years. For example, it can be applied to vehicles, as well as other means of transportation such as aircraft, aerospace vehicles, and ships. For the convenience of description, in this application, a vehicle-mounted HUD is taken as an example for description. However, it should be understood that this does not limit this application.

Specifically, the head-up display uses the principle of optical reflection to project important driving-related information (such as driving speed, battery voltage, water tank temperature, engine speed, vehicle fuel consumption, navigation route, etc.) on the windshield, balancing reflections. In the eyes of the driver, it assists the driver in driving the vehicle, prevents the driver from looking down at the instrument panel and being distracted during driving, improves driving safety, and also brings a better driving experience.

Virtual Image Distance (VID) refers to the distance from the human eye to the virtual image. Field of Vision (FOV) is the angle from the driver's eye as the center to the horizontal and vertical edges of the virtual image.

The technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present application. Obviously, the described embodiments are only some of the embodiments of the present application, rather than all of the embodiments.

Figure 1 is a schematic structural diagram of a head-up display according to an embodiment of the present application. As shown in FIG. 1 , the head-up display 100 includes an image source 10 , a polarization splitting element 20 , a first diffusion element 51 , and a reflecting mirror. 30. Polarization conversion element 40, second diffusion element 52 and reflective component 60. The reflective assembly 60 includes a first free-form mirror 61 and a second free-form mirror 62 .

The image source 10 is used to emit image light. The image light is circularly polarized light. The polarization splitting element 20 is located on the light exit side of the image source 10 . The polarization splitting element 20 is used to reflect the S-state polarized light in the image light to initiate the first optical path, and to transmit the P-state polarized light in the image light to initiate the second optical path. The polarization beam splitter element 20 is, for example, a polarization beam splitter (PBS), but is not limited thereto. For example, the polarization splitting element 20 can also be an optical film with a polarization transflective function, which can transmit P-state polarized light and reflect S-state polarized light. Specifically, the optical film includes, for example, multiple layers of film layers with different refractive indexes that are combined in a certain stacking sequence.

A first diffusion element 51, a first free-form surface mirror 61 and a second free-form surface mirror 62 are arranged in sequence on the first optical path. The reflecting mirror 30 , the polarization conversion element 40 , the second diffusion element 52 , the first free-form surface mirror 61 and the second free-form surface mirror 62 are arranged in sequence on the second optical path.

The first diffusion element 51 and the second diffusion element 52 are used to homogenize the image light and change the viewing angle. The first diffusion element 51 and the second diffusion element 52 are diffusion sheets or microlens array membranes to eliminate the problems of laser speckle and directed light. The diffuser includes at least one of a circular diffuser that can convert the incident light beam into a circular light spot, an elliptical diffuser that can convert the incident light beam into an elliptical light spot, and a flat-top diffuser that can convert the incident light beam into a flat-top distributed light spot. .

The first free-form mirror 61 and the second free-form mirror 62 are used to correct and change the magnification of the virtual image. At least one of the first free-form mirror 61 and the second free-form mirror 62 is a position-adjustable free-form mirror. The position-adjustable free-form mirror can rotate, translate or swing within a preset angle range to adjust the position of the image of the head-up display 100 on the projection medium, so that the image can be clear and complete. The ground display allows the driver to clearly see the virtual image displayed by the HUD projection. In other embodiments, the reflective assembly 60 is not limited to including two free-form mirrors, for example, it may also include more than three free-form mirrors.

The polarization conversion element 40 is used to convert P-state polarized light into S-state polarized light. The polarization conversion element 40 may be a half-wave plate or two quarter-wave plates. When the polarization conversion element 40 is a half-wave plate, the P-state polarized light can be converted once by the half-wave plate to obtain the S-state polarized light. When the polarization conversion element 40 is a quarter-wave plate, the P-state polarized light needs to pass through two quarter-wave plates in sequence and be converted twice to obtain S-state polarized light.

Specifically, after the image light generated by the image source 10 passes through the polarization splitting element 20 , the S-state polarized light in the image light is reflected. Wherein, the S-state polarized light reflected by the polarization splitting element 20 is defined as the first image light. The first image light is homogenized after passing through the first diffusion element 51 and has a small viewing angle. Then, the first image light passes through the first free-form surface mirror 61 and the second free-form surface mirror 62 respectively, and then is reflected to the projection medium (eg, the windshield 200 of the vehicle) to form the first virtual image VI1. After the first virtual image VI1 is incident on the human eye, it appears as a close-up image.

After the image light generated by the image source 10 passes through the polarization splitting element 20, the P-state polarized light in the image light is transmitted. The P-state polarized light is reflected to the polarization conversion element 40 after passing through the reflecting mirror 30 . The polarization conversion element 40 converts P-state polarized light into S-state polarized light. The S-state polarized light converted by the polarization conversion element 40 is defined as the second image light. The second image light is homogenized after passing through the second diffusion element 52 and has a large viewing angle. Then, the second image light passes through the first free-form surface mirror 61 and the second free-form surface mirror 62 respectively, and then is reflected to the projection medium (eg, the windshield 200 of the vehicle) to form a second virtual image VI2. After the second virtual image VI2 is incident on the human eye, it appears as a long-distance image.

For the same driver, the virtual image distance and field of view angle of the first virtual image VI1 and the second virtual image VI2 are different. Among them, the virtual image distance VID1 of the first virtual image VI1 is smaller than the virtual image distance of the second virtual image VI2 away from VID2. The field of view angle of the first virtual image VI1 (the first horizontal field of view angle HFOV1 times the first vertical field of view angle VFOV1, that is, HFOV1×VFOV1) is smaller than the field of view angle of the second virtual image VI2 (the second horizontal field of view angle HFOV2 times the The second vertical field of view angle VFOV2, that is, HFOV2×VFOV2).

Specifically, the first virtual image VI1 and the second virtual image VI2 are projected into the human eye at the same time. Simple information such as speed and fuel level can be displayed in the close-range image (the first virtual image VI1). The close-range image is usually located about 1.8m-2.5m away from the driver, so that the driver can have the best information when encountering an emergency. Response speed. Information that needs to be integrated with the real world, such as traffic information and navigation information, can be displayed in the long-range image (second virtual image VI2). The long-range image can be located 7m away from the driver to match the distance of the external road.

In this head-up display, by arranging a polarizing beam splitting element, the image light is divided into P-state polarized light and S-state polarized light propagating in different optical paths, wherein the S-state polarized light reflected by the polarizing beam splitting element serves as the first image light. The P-state polarized light transmitted by the polarization splitting element is converted into S-state polarized light through the polarization conversion element as the second image light. After the first image light and the second image light are reflected to the projection medium by the reflective component, virtual images with two virtual image distances and two field of view angles are simultaneously generated, which helps to improve driving safety. In addition, in this head-up display, polarization splitting elements are provided to perform polarization splitting, and the first optical path and the second optical path are folded, making the optical path more compact and reducing the size of the head-up display.

In some embodiments, the inclination angle α of the windshield 200 is 40 to 50 degrees. The inclination angle α of the windshield 200 refers to the inclination angle of the windshield 200 relative to the driving center console. Figure 2 is a schematic diagram showing the relationship between the reflectivity of P-state polarized light and S-state polarized light and the tilt angle of the windshield. As shown in Figure 2, the tilt angle of the windshield is 40 degrees to 50 degrees. The reflectivity of P-state polarized light is extremely low, while the reflectivity of S-state polarized light is approximately 20%. Therefore, in the embodiment of the present application, using S-state polarized light as the first image light and the second image light is beneficial to improving the utilization rate of the light source.

Figure 3 is a schematic structural diagram of the image source in Figure 1. The image source 10 is a laser beam scanner (Laser Beam Scanning, LBS). As shown in FIG. 3 , the laser beam scanner includes a laser light source 11 , a beam combining component 12 and a Micro-Electro-Mechanical System (MEMS) micro-mirror 13 . The laser light source 11 is used to emit lasers of different colors. The beam combining component 12 is used to combine laser beams of different colors. The MEMS micro-mirror 13 is used to reflect lasers of different colors as image light. In this embodiment, the laser light source 11 includes a red laser 111 for emitting red laser, a green laser 112 for emitting green laser, and a blue laser for emitting blue laser. 113. The beam combining assembly 12 includes, for example, a first beam splitter (not shown) facing the red laser 111, a second beam splitter facing the green laser 112, and a third beam splitter facing the blue laser 113. . The red laser emitted by the red laser 111 is reflected by the first beam splitter and then emitted. The green laser emitted by the green laser 112 is reflected by the second beam splitter and then directed to the first beam splitter, and penetrates the first beam splitter and mixes with the red light. The blue laser emitted by the blue laser 113 The laser is reflected by the third beam splitter and then penetrates the first beam splitter and the second beam splitter in sequence, and is mixed with the red laser and the green laser.

In other embodiments, the image source 10 further includes, for example, a collimating lens (not shown) between the laser light source 11 and the beam combining component 12 so that the laser acts parallel and uniformly over a longer distance.

Compared with image sources such as Liquid Crystal Display (LCD), Liquid Crystal on Silicon (LCoS) display, and Digital Light Processing (DLP) display, LBS has a small size as an image source. , low thermal power consumption, no need to adjust the focal length when placed, direct imaging on the windshield, strong image penetration, high chroma contrast, and optimized borderless HUD display.

A second aspect of this application provides a vehicle. The vehicle includes a windshield as well as the aforementioned heads-up display. The windshield is the projection medium. The vehicle includes the head-up display of the first aspect, so it has at least the same advantages as the head-up display of the first aspect, which will not be described again.

The above embodiments are only used to illustrate the technical solutions of the present invention and are not limiting. Although the present invention has been described in detail with reference to the preferred embodiments, those of ordinary skill in the art should understand that the technical solutions of the present invention can be modified or equivalently replaced. without departing from the spirit and scope of the technical solution of the present invention.

100: Head-up display

10:Image source

20:Polarization splitting element

30:Reflector

40:Polarization conversion element

51: First diffusion element

52: Second diffusion element

60: Reflective component

61:First freeform mirror

62: Second freeform mirror

VI1: The first virtual image

VI2: Second virtual image

200:windshield

S: S-state polarized light

P:P state polarized light

VID1, VID2: virtual image distance

HFOV1: first horizontal field of view

VFOV1: first vertical field of view

HFOV2: Second horizontal field of view

VFOV2: Second vertical field of view

α:tilt angle

Claims (9)

A head-up display, which is improved in that it includes: an image source, the image source is used to emit image light, and the image light is circularly polarized light; a polarizing light splitting element, the polarizing light splitting element is located at the side of the image source The light exit side is used to reflect the S-state polarized light in the circularly polarized light to start the first optical path, and to transmit the P-state polarized light in the circularly polarized light to start the second optical path, where the polarization split is defined The S-state polarized light reflected by the element is the first image light; a polarization conversion element, the polarization conversion element is located on the second optical path and is used to convert the P-state polarized light into S-state polarized light, where it is defined The S-state polarized light converted by the polarization conversion element is the second image light; a reflective component, the reflective component is located on the first optical path and the second optical path and is used to reflect the first image light and The second image light reaches the projection medium to respectively form a first virtual image and a second virtual image, wherein the first virtual image and the second virtual image have different virtual image distances and different viewing angles; and the first diffusion element and the second Diffusion element; the first diffusion element is located between the polarization splitting element and the reflective component to homogenize the first image light; the second diffusion element is located between the polarization conversion element and the reflective component. between components to homogenize the second image light. The head-up display according to claim 1, wherein the virtual image distance of the first virtual image is smaller than the virtual image distance of the second virtual image; and the field of view angle of the first virtual image is smaller than the field of view angle of the second virtual image. The head-up display according to claim 1, wherein the first diffusion element and the second diffusion element are diffusion sheets or microlens array films, and the diffusion sheets include a light beam capable of converting an incident light beam into a circular light spot. At least one of a circular diffuser, an elliptical diffuser capable of converting the incident light beam into an elliptical light spot, and a flat-top diffuser capable of converting the incident light beam into a flat-top distributed light spot. The head-up display according to claim 1, wherein the head-up display further includes a reflector; the reflector is located on the second optical path to reflect the P-state polarized light transmitted by the polarization splitting element to Polarization conversion element. The head-up display according to claim 1, wherein the reflective component includes at least one position-adjustable free-form mirror, and the free-form mirror is used to change the magnification of the first virtual image and the second virtual image. The head-up display according to claim 1, wherein the polarization conversion element is a half-wave plate or two quarter-wave plates. The head-up display according to any one of claims 1 to 6, wherein the image source is a laser beam scanner, and the laser beam scanner includes: a plurality of laser light sources for emitting different colors. Laser; and MEMS micro-mirrors, used to reflect the lasers of different colors as the image light. A vehicle, which includes: a windshield; and the head-up display according to any one of claims 1 to 7; wherein the windshield is the projection medium. The vehicle according to claim 8, wherein the inclination angle of the windshield relative to the center console of the vehicle is 40 degrees to 50 degrees.

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