Head-up display glass, head-up display system, and vehicle

Abstract

The present disclosure relates to a head-up display glass, a head-up display system and a vehicle. The head-up display glass comprises a glass body and a reflective liquid crystal film. The reflective liquid crystal film is arranged on one side of the glass body. The reflective liquid crystal film comprises cholesteric liquid crystal molecules. The cholesteric liquid crystal molecules are configured to reflect a portion of image light incident on the reflective liquid crystal film, the portion having the same handedness as the cholesteric liquid crystal molecules. The head-up display glass provided by the present disclosure can improve the display brightness of the head-up display.

Description

Technical Field

[0001] This disclosure relates to the field of vehicle technology, and more specifically, to a head-up display glass, a head-up display system, and a vehicle. Background Technology

[0002] Head-up display (HUD), also known as head-up display, works by projecting important driving information such as speed and navigation onto a projection medium, such as the windshield or a specially designed screen in the cockpit, through a designed optical path. This allows the driver to view the information, avoiding the safety hazards caused by the driver looking down at the instrument panel or other driver assistance devices, and increasing driving safety.

[0003] In related technologies, the windshield is typically used as the projection medium for reflecting image light. The image light emitted by the head-up display system's optical engine is reflected by the windshield and enters the human eye, allowing the observer to see the corresponding virtual image. However, the reflection angle of the image light incident on the windshield is close to the Brewster angle, causing the reflectivity of P-polarized light to approach 0, resulting in low brightness of the image observed by the human eye. Utility Model Content

[0004] This disclosure provides a head-up display glass, a head-up display system, and a carrier that can improve the display brightness of the head-up display.

[0005] According to one aspect of this disclosure, a head-up display glass is provided, comprising:

[0006] Glass body;

[0007] A reflective liquid crystal film is disposed on one side of a glass body. The reflective liquid crystal film includes cholesteric liquid crystal molecules, which are used to reflect the portion of image light incident on the reflective liquid crystal film that has the same rotation direction as the cholesteric liquid crystal molecules.

[0008] In one exemplary embodiment of this disclosure, the reflective liquid crystal film includes a substrate and a liquid crystal layer, the liquid crystal layer including the cholesteric liquid crystal molecules, and the liquid crystal layer is disposed on the side of the substrate away from the glass body.

[0009] In one exemplary embodiment of this disclosure, the incident angle of the image light on the liquid crystal layer is equal to the exit angle of the image light from the liquid crystal layer.

[0010] In one exemplary embodiment of this disclosure, the substrate has an alignment groove on the side facing the liquid crystal layer, and the substrate is used to align the optical axis of the cholesteric liquid crystal molecules in the liquid crystal layer with the alignment groove; the liquid crystal layer is used to asymmetrically reflect the image light so that the incident angle of the image light on the liquid crystal layer is not equal to the exit angle of the image light from the liquid crystal layer.

[0011] In one exemplary embodiment of this disclosure, the thickness of the reflective liquid crystal film is 3 micrometers to 6 micrometers.

[0012] In one exemplary embodiment of this disclosure, the glass body includes a first glass and a second glass, with an interlayer provided between the first glass and the second glass; the reflective liquid crystal film is disposed on the side of the first glass near the second glass or on the side of the second glass near the first glass.

[0013] In one exemplary embodiment of this disclosure, a quarter-wave plate is provided on the side of the reflective liquid crystal film away from the glass body.

[0014] According to another aspect of this disclosure, a head-up display system is provided, comprising the head-up display glass described in any of the foregoing claims;

[0015] A head-up display for projecting image light onto the head-up display glass, the image light being reflected at least by the reflective liquid crystal film to the eye box.

[0016] In one exemplary embodiment of this disclosure, the angle between the head-up display glass and the image light emitted by the head-up display is 40° to 70°.

[0017] According to another aspect of this disclosure, a carrier is provided, including the head-up display glass of any of the foregoing.

[0018] The head-up display glass disclosed herein allows cholesteric liquid crystal molecules to selectively reflect one of two circularly polarized light components with opposite rotation directions based on their own chirality. This reflects the portion of the image light with the same rotation direction as the cholesteric liquid crystal molecules toward the eye box, thereby increasing the reflectivity of the image light on the head-up display glass and enhancing the display brightness of the head-up display.

[0019] It should be understood that the above general description and the following detailed description are exemplary and explanatory only, and are not intended to limit this disclosure. Attached Figure Description

[0020] The accompanying drawings, which are incorporated in and form part of this specification, illustrate embodiments consistent with this disclosure and, together with the description, serve to explain the principles of this disclosure. It is obvious that the drawings described below are merely some embodiments of this disclosure, and those skilled in the art can obtain other drawings based on these drawings without any inventive effort.

[0021] Figure 1 This is a schematic diagram illustrating the working principle of the head-up display system disclosed herein.

[0022] Figure 2 This is a schematic diagram of a reflective liquid crystal film according to one embodiment of the head-up display glass of this disclosure.

[0023] Figure 3 This is a schematic diagram of a reflective liquid crystal film according to another embodiment of the head-up display glass of this disclosure.

[0024] Figure 4 This is a schematic diagram of the optical path of one embodiment of the head-up display glass of this disclosure.

[0025] Figure 5 This is a schematic diagram of the optical path of another embodiment of the head-up display glass of this disclosure.

[0026] Explanation of reference numerals in the attached figures:

[0027] 100. Head-up display glass; 200. Head-up display; 300. Eye box; 1. Glass body; 2. Reflective liquid crystal film; 21. Substrate; 211. Alignment groove; 22. Liquid crystal layer; 3. Quarter-wave plate. Detailed Implementation

[0028] Exemplary embodiments will now be described more fully with reference to the accompanying drawings. However, these exemplary embodiments can be implemented in many forms and should not be construed as limited to the embodiments set forth herein; rather, they are provided so that this disclosure will be thorough and complete, and will fully convey the concept of the exemplary embodiments to those skilled in the art. The same reference numerals in the drawings denote the same or similar structures, and therefore detailed descriptions of them will be omitted. Furthermore, the drawings are merely illustrative of this disclosure and are not necessarily drawn to scale.

[0029] The terms “a,” “one,” “the,” “the,” and “at least one” are used to indicate the presence of one or more elements / components / etc.; the terms “including” and “having” are used to indicate an open-ended inclusion and to mean that there may be other elements / components / etc. in addition to the listed elements / components / etc.; the terms “first” and “second” are used only as markers and are not a limitation on the number of objects.

[0030] This disclosure provides a head-up display (HUD) glass 100, a HUD system, and a vehicle. To facilitate explanation, one possible application scenario is illustrated by using the HUD glass 100 and HUD system in an automobile, specifically a car as the vehicle. Those skilled in the art should understand that the HUD glass 100 and HUD system of this exemplary embodiment can also be applied to, for example, sanitation vehicles, fire trucks, and military vehicles, as well as to fields such as shipbuilding and aviation. For example, the vehicle could be an aircraft such as a fighter jet, allowing the driver to track and aim at objects with the assistance of the HUD system. The implementation methods and technical effects of the HUD glass 100, HUD system, and vehicle of this exemplary embodiment are not limited to any specific application scenario.

[0031] To facilitate the explanation of the solutions disclosed herein, the working principle of the head-up display system will first be illustrated by example. (Reference) Figure 1 As shown, the head-up display system may include a head-up display glass 100 and a head-up display 200. The head-up display 200 is used to project image light onto the head-up display glass 100, and the head-up display glass 100 is used to reflect the image light onto the eye box 300 to form a target virtual image corresponding to the image light.

[0032] For example, the head-up display 200 may include an image source and an image adjustment component. The image source emits image light, and the image adjustment component deflects the image light emitted by the image source onto the head-up display glass 100. The head-up display glass 100 may be the glass of a vehicle, such as the windshield of a car, allowing the driver to observe the external environment through the windshield while receiving a virtual image of the target projected by the head-up display 200.

[0033] For example, the image source can be either a display imaging device or a virtual or real image formed by the display imaging device. For instance, the display imaging device may include a liquid crystal display (LCD), whose backlight source may include one or more of lasers, light-emitting diodes (LEDs), organic light-emitting diodes (OLEDs), stimulated fluorescence (SFF) materials, and quantum dot excitation sources; the display imaging device may also include an actively emitting dot matrix screen composed of light-emitting point sources such as LEDs, MicroLEDs, OLEDs, and plasma light-emitting points; or, the display imaging device may also include a projection imaging system based on projection technologies such as Digital Light Processing (DLP), Liquid Crystal on Silicon (LCoS), and Liquid Crystal Display (LCD), driven by light sources such as LEDs, MicroLEDs, OLEDs, lasers, and fluorescence, or combinations thereof, reflected or transmitted through display panels such as Digital Micromirror Display (DMD), LcoS, and LCD, and then projected onto a projection screen via a projection lens; the display imaging device may also include a laser beam scanning (LBS) projection imaging system where a laser beam scans the screen to form an image. All the display imaging devices mentioned above can also serve as image sources, whether real or virtual images formed by one or more refractions or reflections.

[0034] Exemplarily, the image adjustment component includes a mirror, and may also include optical elements such as lenses or waveguides. Exemplarily, in addition to redirecting image light emitted from the image source to the head-up display glass 100, the image adjustment component is also used to adjust the image light, such as magnifying the image and correcting aberrations.

[0035] Eyebox 300 refers to the area where the driver's or observer's eyes are located. The range of eyebox 300 can be determined based on the driver's height, posture, etc. Eyebox 300 defines an effective area for an eye point; only when the observer's eye point is located within this effective area can the observer see a satisfactory virtual image of the target.

[0036] The head-up display 200 projects relevant driving information in front of the driver's field of vision in the form of an image display. In related technologies, there is a problem that the reflectivity of the image light on the inner surface of the windshield is low, resulting in low brightness of the image observed by the human eye.

[0037] For example, in one embodiment, the head-up display 200 can be installed below the instrument panel on the vehicle's center console. When the incident angle of the image light at the head-up display glass 100 is close to a Brewster angle of 60° to 70°, the reflectivity of P-polarized light, whose polarization plane is parallel to the incident plane, is close to zero. However, due to the limitations of the vehicle's interior layout, the angle at which the image light enters the windshield is exactly close to the Brewster angle, resulting in a very low reflectivity of the p-light component in the image light reflected from the windshield, preventing it from entering the eye box 300, thus causing the brightness of the head-up display image to be low.

[0038] In some implementations, particularly for head-up displays 200 that use LCD displays as image sources, the image light transmitted through the linear polarizer of the LCD display is P-light. Therefore, the brightness of the image light will be significantly reduced as it is reflected from the windshield to the eye box 300.

[0039] This disclosure provides a head-up display glass 100, comprising: a glass body 1; and a reflective liquid crystal film 2 disposed on one side of the glass body 1. The reflective liquid crystal film 2 includes cholesteric liquid crystal molecules, which are used to reflect the portion of the image light incident on the reflective liquid crystal film 2 that has the same rotation direction as the cholesteric liquid crystal molecules.

[0040] The head-up display glass 100 disclosed herein contains cholesteric liquid crystal molecules in its reflective liquid crystal film 2. These cholesteric liquid crystal molecules are arranged in a planar state in layers, with slight changes in the long axis direction of adjacent layers, forming a helical structure along the normal of the layers. Thus, the cholesteric liquid crystal molecules can selectively reflect one of two circularly polarized light components with opposite directions of rotation based on their own chirality. The portion of the image light with the same rotation direction as the cholesteric liquid crystal molecules is reflected towards the eye box 300, thereby increasing the reflectivity of the image light in the head-up display glass 100 and improving the display brightness of the head-up display.

[0041] It should be noted that the head-up display glass 100 provided in this disclosure can refer to a projection medium used to reflect image light to the eye box 300. In the prior art, it can typically be the windshield of a vehicle. Those skilled in the art will understand that, with technological advancements, the substrate of the head-up display glass 100, i.e., the glass body 1 described in this disclosure, may not be made of glass; however, this does not exceed the scope of this disclosure. The use of terms such as "windshield," "head-up display glass," and "glass body" in this disclosure is for ease of explanation and understanding, and is not intended to limit the materials of the head-up display glass 100 or the glass body 1.

[0042] For example, the glass body 1 can be laminated glass. For instance, the glass body 1 includes an inner first glass and an outer second glass, with a laminated layer between the first and second glass. The terms "inner side" and "outer side" in this disclosure are relative. "Inner side" can refer to the side closer to the interior of the carrier, i.e., the side closer to the eye box 300; "outer side" can refer to the side located outside the carrier, i.e., the side farther from the eye box 300. The reflective liquid crystal film 2 can be disposed on either side of the first glass, or on either side of the second glass.

[0043] Specifically, the reflective liquid crystal film 2 can be disposed on the side of the first glass away from the second glass. When the image light emitted by the head-up display 200 is incident on the head-up display glass 100, it first enters the reflective liquid crystal film 2 and is reflected by the reflective liquid crystal film 2 toward the eye box 300.

[0044] The reflective liquid crystal film 2 can also be disposed on the side of the first glass closest to the second glass, or on the side of the second glass closest to the first glass. When the image light emitted by the head-up display 200 is incident on the head-up display glass 100, it first enters the first glass. At least a portion of the image light, especially the P-polarized light component, passes through the first glass and enters the reflective liquid crystal film 2, and is reflected by the reflective liquid crystal film 2 towards the eye box 300. In some embodiments of this disclosure, the reflective liquid crystal film 2 is disposed between the first glass and the second glass, for example, on the side of the first glass closest to the second glass or on the side of the second glass closest to the first glass. The inner and outer glass layers can protect the reflective liquid crystal film 2 and prevent it from being worn.

[0045] Exemplarily, the reflective liquid crystal film 2 includes a substrate 21 and a liquid crystal layer 22, the liquid crystal layer 22 comprising cholesteric liquid crystal molecules, and the liquid crystal layer 22 is disposed on the side of the substrate 21 away from the glass body 1. For example, refer to Figure 2 As shown, the substrate 21 can be a plastic film, such as a polyethylene terephthalate (PET) film. A cholesteric liquid crystal layer 22 is coated onto the substrate 21 and cured to form a reflective liquid crystal film 2. The reflective liquid crystal film 2 can be attached to the glass body 1. It should be noted that the phrase "the liquid crystal layer 22 is disposed on the side of the substrate 21 away from the glass body 1" in this disclosure refers to the glass body 1 on which the liquid crystal layer 22 is disposed away from the substrate 21. For example, if the liquid crystal layer 22 is disposed on the side of the second glass closest to the first glass, then the substrate 21 can be attached to the side of the second glass closest to the first glass, and the liquid crystal layer 22 is located on the side of the substrate 21 closest to the first glass.

[0046] In one exemplary embodiment of this disclosure, the thickness of the reflective liquid crystal film 2 is 3 to 6 micrometers. The thickness of the liquid crystal layer 22 is related to the wavelength of the light it selectively reflects, and the reflection of different wavelengths can be controlled by controlling the thickness of the liquid crystal layer 22 coated on the substrate 21. Exemplarily, the reflectivity of the liquid crystal layer 22 for light in the wavelength band of the image light can be greater than 30%, and the transmittance for visible light can be greater than 70%.

[0047] In one exemplary embodiment of this disclosure, the incident angle of the image light at the liquid crystal layer 22 is equal to the exit angle of the image light from the liquid crystal layer 22. The reflection effect of the liquid crystal layer 22 on the image light is approximately specular reflection. The liquid crystal layer 22 is used to reflect the portion of the image light that has the same rotation direction as the cholesteric liquid crystal molecules. For example, if the image light is circularly polarized light with the same rotation direction as the liquid crystal layer 22, then the liquid crystal layer 22 can be used to reflect all the image light; for example, referring to... Figure 4 As shown, the image light L1 is natural light or linearly polarized light, such as P-polarized light. The liquid crystal layer 22 can decompose the image light into two circularly polarized lights L2 and L3 with opposite chirality, reflect the circularly polarized light L2 with the same chirality, and transmit the other circularly polarized light L3.

[0048] In another exemplary embodiment of this disclosure, the substrate 21 is provided with an alignment groove 211 on the side facing the liquid crystal layer 22. The substrate 21 is used to make the optical axis orientation of the cholesteric liquid crystal molecules in the liquid crystal layer 22 consistent with the alignment groove 211. The liquid crystal layer 22 is used to asymmetrically reflect image light so that the incident angle of the image light in the liquid crystal layer 22 is not equal to the exit angle of the image light from the liquid crystal layer 22.

[0049] refer to Figure 3 As shown, the alignment grooves 211 can be nanometer-scale periodic stripes formed on the surface of the substrate 21 by physical friction or laser interference. When liquid crystal is coated on one side of the substrate 21 where the alignment grooves 211 are located to form a liquid crystal layer 22, the liquid crystal molecules align following the orientation of the alignment grooves 211. Simultaneously, the liquid crystal is doped with a chiral agent; the chiral molecules in the chiral agent can induce and twist the orientation of the liquid crystal molecules, causing them to form a helical periodic structure in the direction perpendicular to the substrate 21. The formed liquid crystal layer 22 is referenced... Figure 3 As shown, in addition to the interlayer spiral structure, the liquid crystal layer 22 also has a certain tilt angle in the direction perpendicular to the substrate 21. When the liquid crystal layer 22 reflects image light, the exit angle is the superposition of the incident angle and the light distortion effect of the alignment angle of the cholesteric liquid crystal molecules. In some exemplary embodiments, by controlling the angle of the alignment groove 211, while keeping the incident angle of the image light at the head-up display glass 100 constant, the exit angle of the image light reflected from the reflective liquid crystal film 2 can be adjusted to match the position of the eye box 300.

[0050] In one exemplary embodiment of this disclosure, a quarter-wave plate 3 is provided on the side of the reflective liquid crystal film 2 away from the glass body 1. (See reference...) Figure 5 As shown, the quarter-wave plate 3 can convert linearly polarized light into circularly polarized light. Exemplarily, the image light L1 emitted by the head-up display 200 is P-polarized light with its polarization plane parallel to the incident plane. The incident image light is first converted into circularly polarized light with the same chirality as the cholesteric liquid crystal in the reflective liquid crystal film 2 by the quarter-wave plate 3. The liquid crystal layer 22 can then reflect all of the circularly polarized image light L2. In some embodiments, the liquid crystal layer 22 can achieve 100% reflectivity for P-polarized light. Exemplarily, the transmittance of the liquid crystal layer 22 to ambient natural light is not less than 50%, thus not affecting the driver's observation of the external environment through the head-up display glass 100.

[0051] According to another aspect of this disclosure, a head-up display system is provided, including a head-up display glass 100 as described above and a head-up display 200. The head-up display 200 projects image light onto the head-up display glass 100, the image light being reflected at least on a reflective liquid crystal film 2. For example, the image light is reflected by the reflective liquid crystal film 2 to an eyepiece 300 region, forming a target virtual image corresponding to the image light. For details regarding the structure, principle, and implementation of the head-up display 200 and the head-up display system, please refer to the description of the foregoing exemplary embodiments of this disclosure; further details will not be repeated here.

[0052] In one exemplary embodiment of this disclosure, the angle between the head-up display glass 100 and the image light emitted by the head-up display 200 is 40° to 70°. The head-up display 200 can be installed below the instrument panel of the vehicle's center console to facilitate the emission of image light to the head-up display glass 100.

[0053] According to another aspect of this disclosure, a vehicle is provided, including the head-up display glass 100 of any of the foregoing embodiments. For example, the vehicle may be a car, a ship, or an aircraft. In some embodiments of this disclosure, the vehicle may further include a head-up display 200. For details regarding the structure, principle, and implementation of the head-up display glass 100 and the head-up display 200, please refer to the description of the foregoing exemplary embodiments of this disclosure; further details will not be repeated here.

[0054] Other embodiments of this disclosure will readily occur to those skilled in the art upon consideration of the specification and practice of the utility models disclosed herein. This application is intended to cover any variations, uses, or adaptations of this disclosure that follow the general principles of this disclosure and include common knowledge or customary techniques in the art not disclosed herein. The specification and examples are to be considered exemplary only, and the true scope and spirit of this disclosure are indicated by the appended claims.

Claims

1. A head-up display glass, characterized in that, include: Glass body; A reflective liquid crystal film is disposed on one side of the glass body. The reflective liquid crystal film includes cholesteric liquid crystal molecules, which are used to reflect the portion of the image light incident on the reflective liquid crystal film that has the same rotation direction as the cholesteric liquid crystal molecules.

2. The head-up display glass according to claim 1, characterized in that, The reflective liquid crystal film includes a substrate and a liquid crystal layer, the liquid crystal layer including the cholesteric liquid crystal molecules, and the liquid crystal layer is disposed on the side of the substrate away from the glass body.

3. The head-up display glass according to claim 2, characterized in that, The incident angle of the image light rays on the liquid crystal layer is equal to the exit angle of the image light rays from the liquid crystal layer.

4. The head-up display glass according to claim 2, characterized in that, The substrate has an alignment groove on the side facing the liquid crystal layer. The substrate is used to align the optical axis of the cholesteric liquid crystal molecules in the liquid crystal layer with the alignment groove. The liquid crystal layer is used to asymmetrically reflect the image light so that the incident angle of the image light on the liquid crystal layer is not equal to the exit angle of the image light from the liquid crystal layer.

5. The head-up display glass according to claim 1, characterized in that, The thickness of the reflective liquid crystal film is 3 to 6 micrometers.

6. The head-up display glass according to claim 1, characterized in that, The glass body includes a first glass and a second glass, with an interlayer between the first glass and the second glass; the reflective liquid crystal film is disposed on the side of the first glass near the second glass or on the side of the second glass near the first glass.

7. The head-up display glass according to any one of claims 1 to 6, characterized in that, The reflective liquid crystal film has a quarter-wave plate on the side away from the glass body.

8. A head-up display system, characterized in that, Includes the head-up display glass according to any one of claims 1 to 7; A head-up display for projecting image light onto the head-up display glass, the image light being reflected at least by the reflective liquid crystal film.

9. The head-up display system according to claim 8, characterized in that, The angle between the head-up display glass and the image light emitted by the head-up display is 40° to 70°.

10. A vehicle, characterized in that, include: The head-up display glass according to any one of claims 1 to 7.

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