Head up display system

Abstract

A head-up display (HUD) system is applicable to a windshield element. The HUD system includes a display module and a quarter-wave plate. The display module is disposed below the windshield element and provides an image beam. The display module has a light-emitting surface from which the image beam exits. The quarter-wave plate is disposed between the display module and the windshield element. The optical axis of the quarter-wave plate is tilted from the normal direction of the light-emitting surface of the display module toward a driver's position.

Description

Technical Field

[0001] The present invention relates to a display system, and in particular to a head-up display system. Prior Art

[0002] Head-up display is a flight aid commonly used in aircraft. With the rapid development of electric vehicles, more and more cars are equipped with head-up displays to project vehicle status information such as speed and rotation speed on the front of the windshield for drivers to view.

[0003] Generally speaking, the display modules of the head-up display can be divided into two types: display modules that provide P polarized light and display modules that provide S polarized light. The head-up display including the display module that provides P polarized light has the problem that the reflectivity of the P polarized light on the front windshield is too low. In addition, when a driver wearing polarized sunglasses views the head-up display including the display module that provides P polarized light, the brightness is likely to be too high. On the other hand, when a driver wearing polarized sunglasses views the head-up display including the display module that provides S polarized light, there will be almost no brightness. Summary of the invention

[0004] The present invention provides a head-up display system with excellent optical performance.

[0005] A head-up display system according to an embodiment of the present invention is suitable for a windshield element and includes a display module and a quarter wave plate. The display module is arranged below the windshield element and is used to provide an image beam. The display module has a light-emitting surface, and the image beam is emitted from the light-emitting surface. At least a portion of the image beam is reflected by the windshield element and transmitted to the eyes of the driver. The quarter wave plate is arranged between the display module and the windshield element. The optical axis of the quarter wave plate is inclined from the normal direction of the light-emitting surface of the display module toward the position where the driver is located.

[0006] A head-up display system according to an embodiment of the present invention includes a display module and a quarter-wave plate. The display module is used to provide an image beam, wherein the display module has a light-emitting surface, and the image beam is emitted from the light-emitting surface. The quarter-wave plate is disposed on the display module, wherein an optical axis of the quarter-wave plate is inclined relative to a normal direction of the light-emitting surface of the display module.

[0007] A quarter wave plate according to an embodiment of the present invention comprises a substrate, wherein an optical axis of the quarter wave plate is inclined relative to a normal direction of a plane where the substrate is located. Simple diagram description

[0008] FIG. 1 is a three-dimensional schematic diagram of a head-up display system according to an embodiment of the present invention. FIG. 2 is a cross-sectional schematic diagram of a head-up display system according to an embodiment of the present invention. FIG. 3 is a three-dimensional schematic diagram of a microstructure of a quarter-wave plate according to an embodiment of the present invention. FIG. 4 is a perspective schematic diagram of a display module and a wind shielding element according to an embodiment of the present invention. FIG. 5 is an electron microscope photograph of a cross section of a quarter wave plate according to an embodiment of the present invention. FIG. 6 is a cross-sectional schematic diagram of a head-up display system according to an embodiment of the present invention. FIG. 7 is a cross-sectional schematic diagram of a head-up display system according to an embodiment of the present invention. FIG. 8 is a cross-sectional schematic diagram of a head-up display system according to another embodiment of the present invention. FIG. 9 is a three-dimensional schematic diagram of a head-up display system according to yet another embodiment of the present invention. Implementation

[0009] Reference will now be made in detail to exemplary embodiments of the present invention, examples of which are illustrated in the accompanying drawings. Whenever possible, the same reference numerals are used in the drawings and description to refer to the same or like parts.

[0010] It should be understood that when an element such as a layer, film, region, or substrate is referred to as being "on" or "connected to" another element, it can be directly on or connected to another element, or an intermediate element may also exist. In contrast, when an element is referred to as being "directly on" or "directly connected to" another element, there are no intermediate elements. As used herein, "connected" may refer to physical and / or electrical connections. Furthermore, "electrically connected" or "coupled" may mean that there are other elements between two elements.

[0011] As used herein, "about", "approximately", or "substantially" includes the stated value and the average value within an acceptable deviation range of the particular value determined by one of ordinary skill in the art, taking into account the measurement in question and the particular amount of error associated with the measurement (i.e., the limitations of the measurement system). For example, "about" can mean within one or more standard deviations of the stated value, or within ±30%, ±20%, ±10%, ±5%. Furthermore, as used herein, "about", "approximately", or "substantially" can select a more acceptable deviation range or standard deviation depending on the optical property, etching property or other property, and can apply to all properties without a single standard deviation.

[0012] Unless otherwise defined, all terms (including technical and scientific terms) used herein have the same meaning as commonly understood by one of ordinary skill in the art to which the present invention belongs. It will be further understood that terms such as those defined in commonly used dictionaries should be interpreted as having a meaning consistent with their meaning in the context of the relevant art and the present invention, and will not be interpreted as an idealized or overly formal meaning unless explicitly defined as such herein.

[0013] FIG. 1 is a three-dimensional schematic diagram of a head-up display system according to an embodiment of the present invention. FIG. 2 is a cross-sectional schematic diagram of a head-up display system according to an embodiment of the present invention. FIG. 1 omits the quarter-wave plate 300 of FIG. 2 . For the sake of clarity, directions x, y, and z that are perpendicular to each other are drawn in each figure.

[0014] 1 and 2 , the head-up display system 10 includes a display module 100 for providing an image beam L. The display module 100 has a light emitting surface 100a. The image beam L is emitted from the light emitting surface 100a. In one embodiment, the display module 100 is, for example, a liquid crystal display, including an upper polarizer 110, a lower polarizer 120, a liquid crystal layer 130 located between the upper polarizer 110 and the lower polarizer 120, and a light source 140 disposed under the lower polarizer 120. However, the present invention is not limited thereto, and in other embodiments, the display module 100 may also be other types of displays, such as a micro light emitting diode display (μLED display), etc.

[0015] The head-up display system 10 further includes a windshield element 200, which is disposed in front of the driver's eyes E of the vehicle and above the display module 100. The windshield element 200 is inclined relative to the light-emitting surface 100a of the display module 100. At least a portion of the image beam L provided by the display module 100 can be reflected by the windshield element 200 and transmitted to a driver's eyes E, thereby forming a virtual image M in the driver's brain.

[0016] The head-up display system 10 further includes a quarter wave plate 300, which is disposed on the display module 100 and is located between the display module 100 and the windshield element 200. Specifically, in one embodiment, the quarter wave plate 300 may be disposed on the light-emitting surface 100a of the display module 100. The quarter wave plate 300 and the display module 100 may form an optimized display module DP. In one embodiment, the image beam L provided by the display module 100 may be a P-polarized light, which may be converted into a circularly polarized light after passing through the quarter wave plate 300, and the circularly polarized light may be reflected by the windshield element 200 and transmitted to the driver's eye E. Under the same specific incident angle, the reflectivity of the windshield element 200 to the circularly polarized light is higher than the reflectivity of the windshield element 200 to the P-polarized light. That is, by disposing the quarter wave plate 300 between the display module 100 and the windshield element 200, the reflectivity of the windshield element 200 to the image beam L incident at a specific angle can be increased, thereby increasing the brightness of the virtual image M. In addition, if the driver wears S-polarized sunglasses, since the image beam L reflected by the windshield element 200 is circularly polarized light, a portion of the image beam L will be blocked by the S-polarized sunglasses, and another portion of the image beam L will pass through the S-polarized sunglasses and be transmitted to the driver's eyes E. Therefore, the driver wearing the S-polarized sunglasses can feel a virtual image M with moderate brightness, and is less likely to experience excessive brightness or almost no brightness.

[0017] FIG. 3 is a three-dimensional schematic diagram of a microstructure of a quarter wave plate according to an embodiment of the present invention. Referring to FIG. 1 , FIG. 2 and FIG. 3 , it is worth noting that the optical axis O of the quarter wave plate 300 is tilted from the normal direction N of the light emitting surface 100a of the display module 100 toward the position where the driver is located. In this way, the phenomenon of rainbow stripes can be improved. For example, FIG. 4 is a three-dimensional schematic diagram of a display module and a windshield element according to an embodiment of the present invention. Referring to FIG. 4 , an eye box K defines the range in which the eye E can appear, and the display module 100 emits image beams L1, L2, L3, and L4 respectively, and the image beams L1, L2, L3, and L4 are reflected to the four ends of the eye box Y through the windshield element 200. For example, in one embodiment, the angles between the image light beams L1, L2, L3, L4 and the normal direction N are 29.6°, 37.8°, 21.2° and 27.8°. After taking the maximum and minimum values, it can be obtained that the preferred angle in this embodiment is 21.2°<α≦37.8°, but the present invention is not limited to this.

[0018] In summary, α is determined by the position and angle of the eye box K, the position and angle of the wind shielding element 200, and the position and angle of the normal direction N of the display module 100. In one embodiment, the optical axis O of the quarter wave plate 300 and the normal direction N of the light emitting surface 100a of the display module 100 form an angle α, and 0°<α≦40°.

[0019] FIG5 is an electron microscope photograph of a cross section of a quarter wave plate according to an embodiment of the present invention. Referring to FIG1, FIG2, FIG3 and FIG5, the quarter wave plate 300 includes a substrate 304, wherein the optical axis O of the quarter wave plate 300 is inclined relative to the normal direction (e.g., direction z) of the plane where the substrate 304 is located (e.g., the xy plane where the direction x and the direction y are located). In one embodiment, the quarter wave plate 300 may selectively have a plurality of microstructures 302 formed on the substrate 304, each microstructure 302 extending in an oblique direction d inclined relative to the normal direction N, and the optical axis O of the quarter wave plate 300 is parallel to or coincides with the oblique direction d. In one embodiment, the quarter wave plate 300 may selectively use the microstructure 302 manufactured by the oblique deposition method to form the optical axis O inclined relative to the light output surface 100a. However, the present invention is not limited thereto, and in other embodiments, the quarter wave plate 300 may also form the inclined optical axis O by other methods.

[0020] Referring to FIG. 1 , FIG. 2 , FIG. 3 and FIG. 5 , a first reference plane (e.g., an xz plane where the directions x and z are located) is perpendicular to the light-emitting surface 100a of the display module 100, and a plurality of vertical projections of the plurality of microstructures 302 of the quarter-wave plate 300 on the first reference plane (e.g., an xz plane) are inclined relative to the light-emitting surface 100a of the display module 100. A first angle P is formed between the vertical projection of the microstructure 302 on the first reference plane (e.g., an xz plane) and the normal direction N of the light-emitting surface 100a of the display module 100. In one embodiment, P=90°-2∙AB, where A is the angle between the windshield element 200 and the light-emitting surface 100a of the display module 100, and B is the look down angle, and the look down angle falls within the range of 0° to 20°. Generally speaking, the downward viewing angle will vary according to the vehicle height (such as Sedan / SUV / Large Truck), projection distance (such as PHUD is generally 1~2 meters, AR-HUD is about 2.5 meters~10 meters), and design purpose (such as providing driving information is more upward, and providing entertainment information is more downward). For example, the downward viewing angle of a Sedan equipped with a PHUD that provides entertainment information is 8.12 o~11.71 o, while the downward viewing angle of the same Sedan equipped with an AR-HUD that provides driving information will become 1.42 o~2.86 o; and if the vehicle model is changed to a large truck and equipped with the same AR-HUD, the downward viewing angle will become 3.57 o~7.12 o. Therefore, in theory, there are various possibilities for downward viewing angles, but the downward viewing angles of mass-produced models currently circulating on the market are all in the range of 0 o~20 o.

[0021] FIG6 is a cross-sectional schematic diagram of a head-up display system according to an embodiment of the present invention. Referring to FIG1 and FIG6, the second reference plane (e.g., the yz plane where the directions y and z are located) is perpendicular to the light-emitting surface 100a of the display module 100 and the first reference plane (e.g., the xz plane), and the plurality of vertical projections of the plurality of microstructures 302 on the second reference plane (e.g., the yz plane) are inclined relative to the light-emitting surface 100a of the display module 100. The vertical projections of the microstructures 302 on the second reference plane (e.g., the yz plane) form a second angle Y with the normal direction N of the light-emitting surface 100a of the display module 100.

[0022] FIG. 7 is a cross-sectional schematic diagram of a head-up display system according to an embodiment of the present invention. Referring to FIG. 1 and FIG. 7 , the image beam L provided by the display module 100 is transmitted to the windshield element 200 and forms a projection range R on the windshield element 200. The projection range R has a first projection boundary r1 and a second projection boundary r2 located at the first side and the second side of the first reference plane (e.g., the xz plane), respectively. The light-emitting surface 100a of the display module 100 has a first light-emitting boundary 100a1 and a second light-emitting boundary 100a2 located at the first side and the second side of the first reference plane (e.g., the xz plane), respectively. The third reference plane (e.g., the xy plane where the direction x and the direction y are located) is perpendicular to the first reference plane (e.g., the xz plane) and the second reference plane (e.g., the yz plane). The third reference plane (e.g., the xy plane) is parallel to or coincides with the light-emitting surface 100a. The first projection boundary r1 and the second projection boundary r2 are cut out by the third reference plane (e.g., the xy plane) to form a first projection boundary point p1 and a second projection boundary point p2. The first reference straight line l1 passes through the end of the first light emitting boundary 100a1 closest to the windshield element 200 and the vertical projection of the first projection boundary point p1 on the third reference plane (e.g., xy plane). The first reference straight line l1 and the first reference plane (e.g., xz plane) include an angle C. The second reference straight line l2 passes through the end of the second light emitting boundary 100a2 closest to the windshield element 200 and the vertical projection of the second projection boundary point p2 on the third reference plane (e.g., xy plane). The second reference straight line l2 and the first reference plane (e.g., xz plane) include an angle D.

[0023] Referring to FIG. 1 , FIG. 6 and FIG. 7 , in one embodiment, the vertical projection of the microstructure 302 on the second reference plane (e.g., yz plane) and the normal direction N of the light emitting surface 100a of the display module 100 form a second angle Y. If the microstructure 302 is inclined toward the first light emitting boundary 100a1 of the display module 100, the second angle Y is greater than 0° and less than or equal to the angle C. If the microstructure 302 is inclined toward the second light emitting boundary 100a2 of the display module 100, the second angle Y is greater than 0° and less than or equal to the angle D.

[0024] It must be noted here that the following embodiments use the component numbers and some contents of the previous embodiments, wherein the same number is used to represent the same or similar components, and the description of the same technical contents is omitted. The description of the omitted parts can be referred to the previous embodiments, and the following embodiments will not be repeated.

[0025] FIG8 is a cross-sectional schematic diagram of a head-up display system according to another embodiment of the present invention. The head-up display system 10A of FIG8 is similar to the head-up display system 10 described above, and the difference between the head-up display system 10A of FIG8 further includes a heat-insulating film 220.

[0026] Please refer to FIG. 2 and FIG. 8 , specifically, the windshield element 200, 200A of the head-up display system 10, 10A includes a transparent substrate 210, such as but not limited to glass. The difference between the head-up display system 10A and the aforementioned head-up display system 10 is that the head-up display system 10A further includes a heat-insulating film 220, which is attached to the transparent substrate 210. The heat-insulating film 220 is located between the quarter-wave plate 300 and the transparent substrate 210, and is separated from the quarter-wave plate 300.

[0027] It is worth mentioning that after the heat-insulating film 220 is attached to the transparent substrate 210 of the windshield element 200A, non-uniform stress will naturally be generated, thereby generating non-uniform polarization behavior. Therefore, when the heat-insulating film 220 is used with a conventional display module, a serious color shift problem will occur. However, if the heat-insulating film 220 is used with an optimized display module DP including a quarter-wave plate 300 according to an embodiment of the present invention, the color shift problem can be improved.

[0028] FIG9 is a three-dimensional schematic diagram of a head-up display system according to another embodiment of the present invention. The head-up display system 10B of FIG9 is similar to the head-up display system 10 described above, and the difference between the two is that in the embodiment of FIG1, one optimized display module DP is used in conjunction with one windshield element 200; in the embodiment of FIG8, multiple optimized display modules DP are used in conjunction with one windshield element 200, wherein the relative positions of the multiple optimized display modules DP and the windshield element 200 are different.

[0029] It is worth mentioning that if a plurality of conventional display modules are used with a windshield element 200, the display modules disposed at different positions relative to the windshield element 200 require different polarization states, so it is necessary to customize the production of a plurality of display modules, resulting in excessively high development costs. However, a plurality of optimized display modules DP according to an embodiment of the present invention can be directly disposed at different positions relative to the windshield element 200, without the need to customize the plurality of optimized display modules DP individually.

[0030] 10, 10A, 10B: Head-up display system 100: Display module 100a: light emitting surface 100a1: First light emitting boundary 100a2: Second light emitting boundary 110: Upper polarizer 120: Lower polarizer 130: Liquid crystal layer 140: Light source 200, 200A: Windshield element 210: Transparent substrate 220: Thermal insulation film 300: Quarter wave plate 302: Microstructure 304: Base material A: Angle C, D: Angle DP: Optimized display module d: oblique direction E: Eyes K: Eye box L, L1, L2, L3, L4: Image beam l1: first reference line l2: second reference line M: Virtual Image N: Normal direction O: Optical axis P: First angle p1: first projection boundary point p2: The second projection boundary point R: Projection range r1: first projection boundary r2: second projection boundary x, y, z: direction Y: Second angle α: Angle

Claims

1. A head-up display system suitable for a windshield element, the head-up display system comprising: A display module is disposed below the windshield element and is used to provide an image beam, wherein the display module has a light-emitting surface and the image beam is emitted from the light-emitting surface, wherein at least a portion of the image beam is reflected by the windshield element and transmitted to the eyes of a driver; and a quarter-wave plate is disposed between the display module and the windshield element, wherein an optical axis of the quarter-wave plate is tilted from a normal direction of the light-emitting surface of the display module toward the position of the driver.

2. The head-up display system as claimed in claim 1, wherein the quarter-wave plate has a plurality of microstructures, a first reference plane is perpendicular to the light-emitting surface of the display module, and a plurality of vertical projections of the microstructures on the first reference plane are inclined relative to the light-emitting surface of the display module.

3. The head-up display system as claimed in claim 2, wherein a vertical projection of the microstructure onto the first reference plane forms a first angle P with the normal direction of the light-emitting surface of the display module, P = 90° - 2∙AB, A is an angle between the wind deflector and the light-emitting surface of the display module, and B is a downward viewing angle, wherein the downward viewing angle falls within the range of 0° to 20°.

4. The head-up display system as claimed in claim 2, wherein a second reference plane is perpendicular to the light-emitting surface of the display module and the first reference plane, and the plurality of vertical projections of the microstructures on the second reference plane are inclined relative to the light-emitting surface of the display module.

5. The head-up display system as claimed in claim 4, wherein the image beam is transmitted to the wind deflector and forms a projection range on the wind deflector, the projection range having a first projection boundary and a second projection boundary located on a first side and a second side of the first reference plane, respectively; the light-emitting surface of the display module has a first light-emitting boundary and a second light-emitting boundary located on the first side and the second side of the first reference plane, respectively; a third reference plane is perpendicular to the first reference plane and the second reference plane, and the first projection boundary and the second projection boundary are intersected by the third reference plane to form a first projection boundary point and a second projection boundary point; a first reference line passes through the end of the first light-emitting boundary closest to the wind deflector and the first projection edge. A vertical projection of the boundary point onto the third reference plane, the first reference line and the first reference plane forming an angle C; a second reference line passing through the end of the second light-emitting boundary closest to the windproof element and the vertical projection of the second projection boundary point onto the third reference plane, the second reference line and the first reference plane forming an angle D; a vertical projection of the microstructure onto the second reference plane and the normal direction of the light-emitting surface of the display module forming a second angle Y; the microstructure is inclined toward the first light-emitting boundary of the display module and the second angle Y is greater than 0° and less than or equal to the angle C, or the microstructure is inclined toward the second light-emitting boundary of the display module and the second angle Y is greater than 0° and less than or equal to the angle D.

6. The head-up display system as claimed in claim 1, wherein the wind deflector element includes a transparent substrate, and the head-up display system further includes: A heat-insulating film is attached to the transparent substrate and is located between the quarter-wave plate and the transparent substrate.

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