Heads-up display device for preventing sunlight damage

Abstract

A heads-up display device for preventing sunlight damage, comprising two or four light sensors positioned behind the reflector to detect the intensity of sunlight hitting the reflector, determining whether sunlight backflow has occurred. If sunlight backflow is detected, the concave mirror rotates to prevent prolonged exposure to the display panel, reducing the risk of heat damage. This also minimizes the frequency and duration of interruptions in the images displayed by the heads-up display device.

Description

Technical Field

[0001] This invention relates to head-up displays, specifically a head-up display device that can accurately detect and prevent damage from backlighting, avoid damage to the display panel due to high temperatures, and prevent interruption of image viewing. Prior Technology

[0002] Please refer to Figure 1A. The automotive head-up display (HUD) has a display panel 21, a reflector 3 for folding the light path, and a concave mirror 4 for magnifying the image. In outdoor environments, sunlight SL can penetrate the windshield G and flow back into the HUD's projection path, that is, it is reflected by the concave mirror 4 and the reflector 3 and then focused onto the display panel 21. Since the maximum illuminance of sunlight SL can reach 120,000 Lux, if the exposure time is long enough, the display panel 21 will heat up and may even be damaged due to high temperature.

[0003] Current methods for detecting and counteracting the problem of sunlight backflow include, for example, setting a temperature sensor TS at the edge or periphery of the display panel 21 to detect or determine the temperature of the display panel 21; or setting a light sensor LS at the light outlet to detect the angle and intensity of sunlight; or setting a light sensor LS on the back of the reflector 3 or concave mirror 4 to detect the intensity of sunlight backflow.

[0004] As shown in Figure 1B, when the display panel may be damaged due to high temperature, the concave mirror 4 can be rotated to the angle of interrupting the light path to prevent the sunlight SL from shining on the display panel 21. After the display panel 21 cools down, the concave mirror 4 can be rotated back to the previous angle. However, this method will make it temporarily impossible for the viewer to see the image, and the image will be frequently interrupted when the sunlight is strong, which will also cause trouble and danger to the viewer.

[0005] As shown in Figure 2A, sunlight is not ideal collimated light (scattering angle ≒ 0 degrees). The average distance of the Earth's orbit around the Sun is about 150 million kilometers, and the radius of the Sun is about 695,000 kilometers. From this, it can be deduced that when sunlight shines on the Earth's surface, the scattering angle STA of the direct, unobstructed sunlight SL beam is at least 0.53 degrees (= 2 × tan -1(695000 / 150000000)).

[0006] As shown in Figure 2B, when sunlight SL passes through the windshield G, it is reflected and focused by the concave mirror 4 (focal length F) and the reflector 3, forming a real image S_im of the sun behind the display panel 21. For ease of understanding, the unfolded optical path of the folded optical path by the reflector 3 is shown with dashed lines. Sunlight SL will be imaged at the focal point F of the concave mirror 4. Since the scattering angle STA of sunlight is 0.53 degrees, the diameter h of the real image S_im is approximately 2F × tan(0.53 / 2). Here, the diameter h is independent of the size of the concave mirror 4, but depends on the focal length F of the concave mirror 4.

[0007] As shown in the unfolded optical path, the display panel 21 is located inside the focal length F of the concave mirror 4. When sunlight SL shines on the display panel, the diameter h of the sunlight spot on the display panel S_bsp will be larger than the diameter h. The light intensity at the center of the sunlight spot S_bsp is higher and the temperature rises faster, while the light intensity at the edge of the sunlight spot S_bsp is lower and the temperature rises slower.

[0008] As shown in Figure 3, the incident angle of the sunlight beam SL entering the head-up display (HUD) varies with the relative position of the sun and the vehicle, causing the position of the real image of the sun, S_im, to change accordingly. If the sunlight SL enters the HUD along the projection path, the sunlight spot S_bsp on the display panel 21 will be in the central area; if the sunlight SL enters the HUD at an angle deviating from the projection path, the sunlight spot S_bsp will be on the edge area of ​​the display panel 21. If the deviation angle is too large, the sunlight SL will not illuminate the display panel 21.

[0009] Therefore, if the position of the sunlight spot S_bsp on the display panel can be changed to prevent the same position on the display panel 21 from being continuously within the sunlight spot S_bsp, or even moved to the outside of the display panel 21, the rate at which the display panel 21 heats up can be slowed down under the condition of sunlight backflow, the time for viewers to see the image can be extended, the frequency and duration of image interruption can be reduced, and the display panel 21 will not be damaged by high temperature.

[0010] As shown in Figure 4A, the conventional technique uses a single light sensor LS mounted behind the reflector 3 to detect the intensity of sunlight entering the head-up display (HUD). When sunlight SL enters the HUD, the area illuminated by sunlight SL on the reflector 3 is defined as the beam spot on the reflector S_bsr, and the area illuminated by sunlight on the display panel 21 is defined as the beam spot on the display panel S_bsp. When sunlight SL enters the HUD in the opposite direction along the projection light path, the beam spot on the display panel S_bsp is located in the central area of ​​the display panel 21. Since the light sensor LS is positioned in the central area of ​​the beam spot S_bsr on the reflector 3, a higher light intensity is detected.

[0011] As shown in Figure 4B, if the sun moves in front of or behind the vehicle, the sunlight SL enters the head-up display from an angle deviating from the projection light path. The sunlight spot S_bsp on the display panel moves to the lower or upper half of the display panel 21. At this time, the light sensor LS is located between the center and the edge area of ​​the sunlight spot S_bsr on the reflector, so it detects a moderate light intensity. In the case of Figure 4B, it is difficult to determine whether the position of the sunlight spot S_bsp on the display panel is in the upper or lower half of the display panel 21 using the detection value of the light sensor LS.

[0012] As shown in Figure 4C, if sunlight SL enters the head-up display from a greater angle away from the projection path, it will not illuminate the display panel 21, but rather outside the lower or upper edge of the display panel 21. In this case, the light sensor LS is within the edge of the sunlight spot S_bsr on the reflector, so the light sensor LS detects a moderate light intensity. In the situation shown in Figure 4C, it is difficult to determine whether sunlight SL is illuminating the upper or lower edge of the display panel 21 from the detection value of the light sensor LS. Summary of the Invention

[0013] In view of the problems of the prior art, the purpose of this invention is to provide a head-up display device that can accurately detect backlighting and reduce damage, avoid damage to the display panel due to high temperature and reduce interruption of image viewing.

[0014] This invention provides a head-up display device that projects an image light onto a windshield. The device includes a display module with a display panel and a backlight element for generating the image light; a reflector for reflecting the image light from the display module; a concave mirror for reflecting the image light from the reflector back to the windshield, the concave mirror being rotatable upwards or downwards; and a light sensing module disposed on the side of the reflector away from the concave mirror. The light sensing module has a first light sensor and a second light sensor to detect sunlight entering the head-up display device and generate a first light intensity value and a second light intensity value. The area of ​​sunlight illuminating the reflector is defined as a sunlight spot on the reflector. The area irradiated on the display panel is defined as a sunlight spot on the display panel; the first light sensor is disposed on the upper half of the reflector, and when the sunlight shines on the outer side of the lower edge of the display panel, the first light sensor is located on the outer side of the upper edge of the sunlight spot on the reflector; the second light sensor is disposed on the lower half of the reflector, and when the sunlight shines on the outer side of the upper edge of the display panel, the second light sensor is located on the outer side of the lower edge of the sunlight spot on the reflector; when the sunlight shines on the display panel to form the sunlight spot on the display panel, both the first light sensor and the second light sensor are within the sunlight spot on the reflector; when there is no sunlight spot on the display panel, at least one of the first light sensor and the second light sensor is not within the sunlight spot on the reflector.

[0015] The light sensing module further includes a third light sensor and a fourth light sensor, generating a third light intensity value and a fourth light intensity value. The third light sensor is located on the left half of the reflector, and when sunlight shines on the outer left edge of the display panel, the third light sensor is located on the outer left edge of the sunlight spot on the reflector. The fourth light sensor is located on the right half of the reflector, and when sunlight shines on the outer right edge of the display panel, the fourth light sensor is located on the outer right edge of the sunlight spot on the reflector. When there is a sunlight spot on the display panel, all the light sensors are within the sunlight spot on the reflector; when there is no sunlight spot on the display panel, at least one of the light sensors is not within the sunlight spot on the reflector.

[0016] The present invention also provides a head-up display device that projects an image light onto a windshield. The device includes: a display module having a display panel and a backlight element for generating the image light; a reflector for reflecting the image light from the display module; a concave mirror for reflecting the image light from the reflector onto the windshield, the concave mirror being rotatable upwards or downwards; and a light sensing module disposed on the side of the reflector away from the concave mirror. The light sensing module has a first light sensor, a second light sensor, a third light sensor, and a fourth light sensor, which detect sunlight entering the head-up display device and generate a first light intensity value, a second light intensity value, a third light intensity value, and a fourth light intensity value. The area of ​​the sunlight illuminating the reflector is defined as a reflector sunlight spot, and the area of ​​the sunlight illuminating the display panel is defined as a display panel sunlight spot. The first light sensor is disposed on the upper left half of the reflector. When sunlight illuminates the windshield... The first light sensor is located outside the lower left edge of the display panel, and outside the upper left edge of the sunlight spot on the reflector. The second light sensor is located on the upper right half of the reflector, and when sunlight shines on the lower right edge of the display panel, the second light sensor is located outside the upper right edge of the sunlight spot on the reflector. The third light sensor is located on the lower right half of the reflector, and when sunlight shines on the upper right edge of the display panel, the third light sensor is located outside the lower right edge of the sunlight spot on the reflector. The fourth light sensor is located on the lower left half of the reflector, and when sunlight shines on the upper left edge of the display panel, the fourth light sensor is located outside the lower left edge of the sunlight spot on the reflector. When sunlight shines on the display panel and forms a sunlight spot, all light sensors are within the sunlight spot on the reflector; when there is no sunlight spot on the display panel, at least one of the light sensors is not within the sunlight spot on the reflector.

[0017] When the light intensity values ​​detected by the light sensors all exceed a medium intensity threshold, and the duration reaches a first time threshold, the concave mirror rotates for the first time from an initial angle, either upwards or downwards. The minimum angle of rotation of the concave mirror is 0.265 degrees.

[0018] After the concave mirror rotates for the first time, if one of the light intensity values ​​is lower than a low intensity threshold and the duration reaches a second time threshold, the concave mirror rotates back to the initial angle; otherwise, the concave mirror rotates a second time in the opposite direction, and the angle value of the second rotation is twice the angle value of the first rotation.

[0019] After the concave mirror rotates twice, if one of the light intensity values ​​is lower than a low intensity threshold and the duration reaches the second time threshold, the concave mirror rotates back to the initial angle; otherwise, the concave mirror is controlled to rotate to a stopping angle, maintained for a closing time, and then the concave mirror is controlled to rotate back to the initial angle.

[0020] The reflector is a reflective polarizer that allows P-polarized waves to pass through and reflects S-polarized waves.

[0021] Among them, a light-reducing film is provided between the reflective polarizer and the photosensitive module. The reflective polarizer allows P-polarized waves to pass through and reflects S-polarized waves. The light-reducing film attenuates 60-90% of the light and has a surface reflectivity of less than 15%. Simple Explanation of the Diagram

[0022] Figure 1A is a schematic diagram of a conventional head-up display device experiencing backlighting.

[0023] Figure 1B is a schematic diagram of rotating the concave mirror when sunlight backflows into a conventional head-up display device.

[0024] Figure 2A is a schematic diagram of sunlight shining on the Earth.

[0025] Figure 2B is a schematic diagram of sunlight forming an image inside a head-up display.

[0026] Figure 3 is a schematic diagram showing the change in the position of sunlight as it is projected inside the head-up display.

[0027] Figure 4A is a schematic diagram of a conventional head-up display with a light sensor installed when sunlight backflow occurs.

[0028] Figure 4B is a schematic diagram showing the change in the position of the sunlight image when a sunlight backflow occurs after a light sensor is installed on a conventional head-up display.

[0029] Figure 4C is another schematic diagram showing the change in the position of sunlight imaging when a conventional head-up display with a light sensor installed experiences backlighting.

[0030] Figure 5A is a schematic diagram of the head-up display in the embodiment when sunlight shines back on it.

[0031] Figure 5B is another schematic diagram of the head-up display in the embodiment when sunlight shines back on it.

[0032] Figure 5C is a schematic diagram of the change in the position of the sunlight image when the head-up display of the embodiment experiences backlighting.

[0033] Figure 5D is another schematic diagram showing the change in the position of the sunlight image when the head-up display of the embodiment experiences backlighting.

[0034] Figure 6A is a schematic diagram showing the placement of the two light sensors.

[0035] Figure 6B shows another schematic diagram of the placement of the two light sensors.

[0036] Figure 6C shows another schematic diagram of the placement of the two light sensors.

[0037] Figure 7A is a schematic diagram of how the concave mirror is rotated to adjust the eye position and the change in the height of the virtual image.

[0038] Figure 7B is another schematic diagram showing how rotating a concave mirror can adjust the eye position and the height of the virtual image.

[0039] Figure 7C is a schematic diagram showing the change in the height of the virtual image when the concave mirror rotates.

[0040] Figure 7D is another schematic diagram showing the change in the height of the virtual image when the concave mirror rotates.

[0041] Figure 7E is a schematic diagram of the sunlight spot reflected by the concave mirror at different eye angles.

[0042] Figure 8A is a schematic diagram of the position of the real image of the sun when sunlight backflow occurs.

[0043] Figure 8B is a schematic diagram showing how rotating the concave mirror moves the real image of the sun when sunlight backflow occurs.

[0044] Figure 8C is another schematic diagram showing how rotating the concave mirror moves the real image of the sun when sunlight backflow occurs.

[0045] Figure 9A is a schematic diagram of the sunlight spot on the display panel.

[0046] Figure 9B is a schematic diagram of the display panel before and after the sunlight spot on the display panel moves.

[0047] Figure 9C is another schematic diagram showing the movement of the sunlight spot on the display panel before and after.

[0048] Figure 9D is another schematic diagram showing the movement of the sunlight spot on the display panel before and after.

[0049] Figure 9E is another schematic diagram showing the movement of the sunlight spot on the display panel before and after.

[0050] Figure 9F is a schematic diagram of the sunlight spot on the display panel moving away from the display panel.

[0051] Figure 9G is another schematic diagram showing the movement of sunlight spots away from the display panel.

[0052] Figure 10A is a schematic diagram showing the viewing image at a preset height when sunlight shines back onto the head-up display in the embodiment.

[0053] Figure 10B is a schematic diagram of the concave mirror in Figure 10A after its first rotation.

[0054] Figure 10C is a schematic diagram of the concave mirror after its second rotation in Figure 10B.

[0055] Figure 10D is a schematic diagram showing the interruption of the optical path after the concave mirror in Figure 10C is rotated significantly.

[0056] Figure 11A is another schematic diagram showing the viewing image at a preset height when sunlight shines back onto the head-up display in the embodiment.

[0057] Figure 11B is a schematic diagram of the concave mirror in Figure 11A after rotation.

[0058] Figure 12A is another schematic diagram showing the viewing image at a preset height when sunlight shines back onto the head-up display in the embodiment.

[0059] Figure 12B is a schematic diagram of the concave mirror in Figure 12A after rotation.

[0060] Figure 13A is a schematic diagram of the optical path of the reflector using a reflective polarizer in the embodiment.

[0061] Figure 13B is another optical path diagram of the reflector using a reflective polarizer in the embodiment.

[0062] Figure 13C is a partially magnified optical path diagram of the reflective polarizer used in the embodiment.

[0063] Figure 13D is a magnified optical path diagram of Figure 13C with an added neutral density filter.

[0064] Figure 14A is a flowchart of the operation method for detecting and responding to situations where sunlight is obstructed.

[0065] Figure 14B is a flowchart of the operation method for detecting and responding to situations where sunlight is obstructed.

[0066] Figure 14C is a flowchart of the operation method for detecting and responding to situations where sunlight is obstructed.

[0067] Figure 15A is another flowchart of the operation method for detecting and responding to situations of reverse sunlight.

[0068] Figure 15B is another flowchart of the operation method for detecting and responding to situations of backflow of sunlight.

[0069] Figure 15C is another flowchart of the operation method for detecting and responding to situations of backflow of sunlight.

[0070] Figure 16A is a schematic diagram showing the placement of the four light sensors in the embodiment.

[0071] Figure 16B is a schematic diagram showing the placement of the four light sensors in the embodiment.

[0072] Figure 16C is a schematic diagram showing the placement of the four light sensors in the embodiment.

[0073] Figure 16D is a schematic diagram showing the placement of the four light sensors in the embodiment.

[0074] Figure 17 is a schematic diagram of the four light sensors in the embodiment and the sunlight shining on different positions of the display panel.

[0075] Figure 18 is a schematic diagram of the four light sensors in the embodiment and the display panel without sunlight shining on it.

[0076] Figure 19A is a flowchart of the operation method for detecting and responding to sunlight backflow using four light sensors.

[0077] Figure 19B is a flowchart of the operation method for detecting and responding to sunlight backflow using four light sensors.

[0078] Figure 19C is a flowchart of the operation method for detecting and responding to sunlight backflow using four light sensors.

[0079] Figure 20A is a schematic diagram of another installation location of the four light sensors in the embodiment.

[0080] Figure 20B is a schematic diagram of another installation location of the four light sensors in the embodiment.

[0081] Figure 20C is a schematic diagram of another installation location of the four light sensors in the embodiment.

[0082] Figure 20D is a schematic diagram of another installation location of the four light sensors in the embodiment.

[0083] Figure 21 is a schematic diagram showing another setting of the four light sensors and different positions of the display panel illuminated by sunlight.

[0084] Figure 22 is a schematic diagram showing another setting of the four light sensors and a display panel where sunlight does not shine on it.

[0085] Figure 23A is a flowchart of the operation method for detecting and responding to sunlight backflow at another location of the four light sensors.

[0086] Figure 23B is a flowchart of the operation method for detecting and responding to sunlight backflow at another location of the four light sensors.

[0087] Figure 23C is a flowchart of the operation method for detecting and responding to sunlight backflow at another location of the four light sensors. Implementation

[0088] To illustrate the technical content and features of this invention, the following embodiments are provided for description. The up, down, left, and right directions of each element defined in the following description are defined as the up, down, left, and right directions when facing the surface of the element. The front, back, left, right, up, and down directions of a vehicle are defined according to the front, back, left, right, up, and down directions of the driver (i.e., the viewer).

[0089] 5A, provided embodiments of the invention are a head-up display device capable of being used with a windshield G comprising: a display module 2 for projecting an image light D comprising a display panel 21 and a backlight element 22 ; a reflector 3 which reflects the image light D;

[0090] The sunlight SL is injected from the outside through the windshield G into the concave mirror 4 , which is then reflected by the reflector 3 to the display module 2 . At this time, the reflector 3 reflects most of the sunlight SL and allows part of the sunlight SL to penetrate, for example, 5%~50%, allowing the light sensor module 5 to detect the penetrating sunlight SL.

[0091] The light sensors LS 1 , LS 2 are soldered on the circuit board 50 to form the light sensing module 5 , which is then fixed at the rear of the reflector 3 . Photosensors LS1, LS2 are capable of converting light energy into electronic signals, which can be, but are not limited to, photoresistors, photodiodes, photosensitive transistors, or other sensors that can detect light intensity, energy, the detected spectrum can be visible light, infrared light, or ultraviolet light.

[0092] As shown in Figure 5B , when the sunlight SL enters the head-up display through the windshield G in the reverse direction along the projected light path at noon on a clear sky, the display panel sunlight spot S_bsp appears in the central area of ​​the display panel 21. At this time, for example, about 15% of the sunlight SL penetrates the reflector 3. Both light sensors LS1 and LS2 are reflecting the mirror sunlight spot S_b sr, are located between the central and edge areas of the reflector sunlight spot S_bsr, so both the first light sensor LS1 and the second light sensor LS2 detect medium light intensity values ​​(about 4000~8000Lux).

[0093] As shown in Figure 5C, if the sun moves in front of the vehicle, the sunlight SL enters the head-up display at an angle deviating from the projection light path. The sunlight spot S_bsp on the display panel is in the lower half of the display panel 21. At this time, the first light sensor LS1 and the second light sensor LS2 will be located at the edge and center of the sunlight spot S_bsr on the reflector, respectively. The first light sensor LS1, located at the edge of the sunlight spot S_bsr, will detect a medium light intensity value (approximately 4000~8000 Lux), while the second light sensor LS2, located in the center of the sunlight spot S_bsr, will detect a higher light intensity value (approximately above 8000 Lux).

[0094] In another scenario, the sun moves behind the vehicle, and the sunlight spot S_bsp on the display panel will be in the upper half of the display panel 21. At this time, the first light sensor LS1 is located in the central area of ​​the sunlight spot S_bsr on the reflector and measures a high light intensity value (above 8,000 Lux), while the second light sensor LS2 is located in the edge area of ​​the sunlight spot S_bsr on the reflector and measures a medium light intensity value (approximately 4,000 to 8,000 Lux).

[0095] Therefore, by measuring the light intensity values ​​detected by the first light sensor LS1 and the second light sensor LS2, it can be determined whether the sunlight spot S_bsp on the display panel is in the lower half or the upper half of the display panel 21.

[0096] As shown in Figure 5D, if the sun moves further in front of or behind the vehicle, the angle at which sunlight SL deviates from the projection light path will be greater, and it will not shine on the display panel 21. Instead, it will move downwards or upwards to outside the display panel 21. At this time, one of the first light sensor LS1 and the second light sensor LS2 will be outside the range of the sunlight spot S_bsr on the reflector. Therefore, only one of the first light sensor LS1 and the second light sensor LS2, which is located within the range of the sunlight spot S_bsr on the reflector, will detect a medium light intensity value (above approximately 4000 Lux), while the other light sensor, which is outside the range of the sunlight spot S_bsr on the reflector, will detect a lower light intensity value (approximately 0~2000 Lux).

[0097] For example, if the first light sensor LS1 measures a low light intensity value (approximately 0~2000 Lux) and the second light sensor LS2 measures a medium light intensity value (approximately 4000 Lux or more), it can be determined that the sunlight SL is not shining on the display panel 21 after being reversed, but is on the outer side of the lower edge of the display panel 21.

[0098] For example, if the first light sensor LS1 measures a medium light intensity value (above 4000 Lux) and the second light sensor LS2 measures a low light intensity value (around 0~2000 Lux), it can be determined that the sunlight SL is not shining on the display panel 21 after being reversed, but is on the outer edge of the upper edge of the display panel 21.

[0099] In this embodiment, the low intensity threshold of the light intensity value can be defined as 2000 Lux, the medium intensity threshold can be defined as 4000 Lux, and the high intensity threshold can be defined as 8000 Lux.

[0100] The positions of light sensors LS1 and LS2 can be defined by the change in the sunlight spot S_bsr of the reflector. When the concave mirror 4 is positioned at the middle angle of its rotation adjustment range, and sunlight SL illuminates the outer edge of the lower edge of the display panel 21, the first light sensor LS1 is positioned outside the upper edge of the sunlight spot S_bsr of the reflector 3 at this time. When the concave mirror 4 is positioned at the middle angle of its rotation adjustment range, and sunlight SL illuminates the outer edge of the upper edge of the display panel 21, the second light sensor LS2 is positioned outside the lower edge of the sunlight spot S_bsr of the reflector 3 at this time. If sunlight SL illuminates the display panel 21, both light sensors LS1 and LS2 will be within the range of the sunlight spot S_bsr of the reflector. If sunlight SL does not illuminate the display panel 21, at least one light sensor will not be within the range of the sunlight spot S_bsr of the reflector.

[0101] The positions of the light sensors LS1 and LS2 have been described above. For ease of explanation, Figures 6A, 6B, and 6C show the folded optical path of the reflector 3 as an unfolded optical path. In this illustration, the sunlight reflected by the reflector 3 extends behind the reflector 3, and the display panel 21 appears to be located directly behind the reflector 3. As shown in Figure 6A, when the sunlight spot S_bsp on the display panel is in the central area of ​​the display panel 21 (corresponding to Figure 5B), both light sensors LS1 and LS2 are within the range of the sunlight spot S_bsr on the reflector 3.

[0102] As shown in Figure 6B, when the sunlight spot S_bsp on the display panel is in the lower half or upper half of the display panel 21 (corresponding to Figure 5C), the two light sensors LS1 and LS2 are both within the range of the sunlight spot S_bsr on the reflector 3.

[0103] As shown in Figure 6C, when sunlight SL shines on the outer side of the lower or upper edge of the display panel 21 (corresponding to Figure 5D), one of the first light sensors LS1 and LS2 is located on the outer side of the upper or lower edge of the sunlight spot S_bsr on the reflector 3. When sunlight SL shines on the outer side of the lower edge of the display panel 21, the first light sensor LS2 is located on the outer side of the upper edge of the sunlight spot S_bsr on the reflector 3 at this time. When sunlight SL shines on the outer side of the upper edge of the display panel 21, the second light sensor LS2 is located on the outer side of the lower edge of the sunlight spot S_bsr on the reflector 3 at this time.

[0104] To ensure that viewers of different heights can see the projected image, the height of the eye position can be adjusted by rotating the concave mirror 4, as shown in Figure 7A. The middle angle of its angle adjustment range is the middle eye position E_m. Rotating the concave mirror 4 upwards (counterclockwise in the figure) can adjust it to a lower eye position E_d, which is suitable for viewers of shorter heights. At this time, the height of the virtual image VI_d seen will be slightly lower than the virtual image VI_m set at the middle eye position E_m.

[0105] As shown in Figure 7B, when the concave mirror 4 is rotated downwards from the angle of the middle eye position E_m (clockwise in the figure), it can be adjusted to a higher eye position E_u to suit taller viewers. At this time, the height of the virtual image VI_u seen will be slightly higher than the virtual image VI_m set at the middle eye position E_m.

[0106] The position of sunlight shining on the display panel 21 can also be controlled by rotating the concave mirror 4, preventing the same position from being continuously exposed to high-intensity sunlight, or preventing sunlight from shining on the display panel 21 at all. As long as the rotation angle is not large, the difference in image height is not easily noticed by the viewer.

[0107] As shown in Figure 7C, when the concave mirror 4 is rotated slightly upwards, if the viewer's eyes are still at the same eye position E_m, the height of the virtual image VI_d will be slightly lower than the virtual image VI_m set at the previous eye position. The viewer can still see the image and the height difference is not significant.

[0108] As shown in Figure 7D, when the concave mirror 4 rotates downwards slightly, if the viewer's eyes are still at the same eye position E_m, the height of the virtual image VI_u will be slightly higher than the virtual image VI_m set at the previous eye position. The viewer can still see the image and the height difference is not significant.

[0109] The concave mirror 4 has a very small rotatable angle range, for example, within 5 degrees. Furthermore, the amount of light entering the concave mirror 4 is limited by the light exit OL and the concave mirror 4. Therefore, at different angles, the position and size of the reflected sunlight spot S_bsr generated by the sunlight SL flowing back along the projection light path are almost the same, as shown in Figure 7E. When the concave mirror 4 is set at the angle that projects the image light to the central eye position E_m, if the sunlight SL enters the head-up display in reverse along the projection light path at this angle, the sunlight spot S_bsp on the display panel is in the central area of ​​the display panel 21. The position and size of the reflected sunlight spot S_bsr are the same as in Figure 5B. The same applies when the concave mirror 4 is set at an angle that projects image light onto the lower eye level E_d. If sunlight SL enters the head-up display in the opposite direction along the angle of the projected light path at this time, the sunlight spot S_bsp on the display panel 21 is in the central area, and the position and size of the sunlight spot S_bsr on the reflector are the same as in Figure 5B. When the concave mirror 4 is set at an angle that projects image light onto the higher eye level E_u, if sunlight SL enters the head-up display in the opposite direction along the angle of the projected light path at this time, the sunlight spot S_bsp on the display panel 21 is in the central area, and the position and size of the sunlight spot S_bsr on the reflector are the same as in Figure 5B. Therefore, the light sensors LS1 and LS2 can determine the situation of sunlight backflow when the concave mirror 4 is at different angles.

[0110] When the head-up display detects a risk of high temperature due to sunlight backflow, the concave mirror 4 can rotate by a minimum angle θ, so that the image of the sun moves and does not overlap with the original image area, thus avoiding most of the sunlight spots S_bsp on the display panel from continuously heating the same area of ​​the display panel 21.

[0111] As shown in Figure 8A, the direct, unobstructed sunlight SL beam has a scattering angle STA of approximately 0.53 degrees. After reflection, the sunlight SL at each point on the concave mirror 4 projects onto the reflecting mirror 3 with a diffusion angle of approximately 0.53 degrees. All the projected beams from all positions on the concave mirror 4 illuminated by sunlight SL overlap at the focal point of the concave mirror 4, forming a real image of the sun, S_im. Therefore, to move the real image of the sun, S_im, to an angle that does not overlap with the original imaging area, the sunlight beam projected onto the display panel 21 needs to be rotated by at least 0.53 degrees. This rotation angle is approximately twice the rotation angle of the concave mirror, meaning the minimum rotation angle θ of the concave mirror is at least 0.265 degrees, or half the sunlight scattering angle STA.

[0112] As shown in Figure 8B, when the concave mirror 4 is rotated upwards by a minimum angle θ (0.265 degrees), the sunlight beam projected onto the display panel 21 rotates upwards by approximately 0.53 degrees, and the real image of the sun S_im behind the display panel 21 does not overlap with its original position as shown in Figure 8A. Furthermore, as shown in Figure 8C, when the concave mirror 4 is rotated downwards by 2θ (0.53 degrees), the sunlight beam projected onto the display panel 21 rotates downwards by approximately 1.06 degrees, and the real image of the sun S_im behind the display panel 21 also does not overlap with its original position as shown in Figure 8A. In fact, within the viewer's acceptable range, as long as the rotation angle of the concave mirror 4 is greater than the minimum angle θ, the desired effect can be achieved.

[0113] As shown in Figure 9A, the intensity distribution of the sunlight spot S_bsp on the display panel 21 is approximately a trapezoidal distribution with a higher intensity in the central area and lower intensity at the two side edges. First, the concave mirror 4 is rotated to move the real image S_im to a non-overlapping position, as shown in Figure 9B. Then, the concave mirror 4 is rotated in the other direction to move the real image S_im to another non-overlapping position, as shown in Figure 9C. Even though the sunlight spot S_bsp on the display panel 21 still partially overlaps before and after the movement, the light intensity at the edges of the sunlight spot S_bsp is significantly weaker, resulting in slower heating. This effectively prevents the same location on the display panel 21 from continuously overheating and being damaged, and extends the time the viewer can see the image, reducing the frequency and duration of image interruptions.

[0114] As shown in Figures 9D and 9E, the rotation angle of the concave mirror 4 can be slightly larger within the acceptable range for the viewer, while maintaining the visibility of the image. If the sunlight SL does not shine on the display panel 21 after rotation, the damage from the sunlight SL can be more effectively avoided.

[0115] As shown in Figure 9F, when the light sensors LS1 and LS2 detect and determine that the sunlight spot S_bsp on the display panel is located on the upper half of the display panel 21, the concave mirror 4 can be rotated to an angle that allows the sunlight spot S_bsp on the display panel to leave from above the display panel 21. This will change the angle with minimal impact on the viewer, preventing the sunlight SL from shining on the display panel 21 and effectively avoiding sunlight damage.

[0116] As shown in Figure 9G, when the light sensors LS1 and LS2 detect and determine that the sunlight spot S_bsp on the display panel is in the lower half of the display panel 21, the concave mirror 4 can be rotated to an angle that allows the sunlight spot S_bsp on the display panel to leave from below the display panel 21. This will change the angle with minimal impact on the viewer, preventing the sunlight SL from shining on the display panel 21 and effectively avoiding damage from the sunlight SL.

[0117] As shown in Figure 10A, the concave mirror 4 is set at the middle angle of its rotation adjustment range, and strong sunlight SL flows back into the head-up display. The sunlight spot S_bsp on the display panel is in the central area of ​​the display panel 21. The first light sensor LS1 and the second light sensor LS2 are within the range of the sunlight spot S_bsr on the reflector, and both detect light intensity values ​​higher than the medium intensity threshold of 4000 Lux.

[0118] The smaller the difference in light intensity detected by the two light sensors LS1 and LS2, for example, if the difference is less than the low difference threshold of 1000 Lux, it means that the position of the sunlight spot S_bsp on the display panel is closer to the central area of ​​the display panel 21. At this time, the angle of the concave mirror 4 is the initial angle, and the image VI seen by the viewer is at the preset height.

[0119] When the light intensity of both the first light sensor LS1 and the second light sensor LS2 exceeds a medium intensity threshold and remains above a first time threshold, the concave mirror 4 can be rotated upwards from its initial angle, as shown in Figure 10B, causing the sunlight spot S_bsp on the display panel to move upwards from the position of the display panel 21. This means that the rotation direction of the concave mirror 4 is the direction in which the sunlight spot S_bsr on the reflector moves from the position of the reflector 3 towards the location of the first light sensor LS1, so that the first light sensor LS1 on the back side of the reflector 3 remains within the range of the sunlight spot S_bsr on the reflector, so as to detect light intensity values ​​higher than the medium intensity threshold of 4000 Lux, and even higher than the high intensity threshold of 8000 Lux. As for the second light sensor LS2, it moves away from the range of the sunlight spot S_bsr on the reflector and detects light intensity values ​​lower than the low intensity threshold of 2000 Lux.

[0120] The greater the difference between the light intensity detected by the first light sensor LS1 and the light intensity detected by the second light sensor LS2 (e.g., the difference is greater than the high difference threshold of 4000 Lux), the more likely the sunlight spot S_bsp is located on the upper half of the display panel 21. When the second light sensor LS2 is below the low intensity threshold of 2000 Lux, it means that the sunlight SL is no longer shining on the display panel 21. At this time, the viewer can still see the virtual image VI, but the image height is slightly lower than the preset height.

[0121] If sunlight SL continues to shine on display panel 21, and the light intensity values ​​detected by the first light sensor LS1 and the second light sensor LS2 are not lower than the low intensity threshold and remain above the second time threshold, the concave mirror 4 can be rotated downwards by a slightly larger angle, as shown in Figure 10C. The sunlight spot S_bsp on the display panel will move downwards at the position of display panel 21. This means that the direction of rotation of the concave mirror 4 is the direction in which the sunlight spot S_bsr on the reflector moves from the position of reflector 3 towards the position of the second light sensor LS2. The first light sensor LS1 moves out of the range of the sunlight spot S_bsr on the reflector and detects a light intensity value lower than the low intensity threshold of 2000 Lux, while the second light sensor LS2 enters the range of the sunlight spot S_bsr on the reflector and detects a light intensity value higher than the medium intensity threshold of 4000 Lux, and even higher than the high intensity threshold of 8000 Lux.

[0122] The greater the light intensity detected by the second light sensor LS2 is compared to the light intensity detected by the first light sensor LS1 (e.g., a difference greater than the high difference threshold of 4000 Lux), the more likely the sunlight spot S_bsp is located on the lower half of the display panel 21. Conversely, when the light intensity detected by the first light sensor LS1 is below the low intensity threshold of 2000 Lux, it indicates that sunlight SL is no longer shining on the display panel 21. In this case, the viewer can still see the virtual image VI, but the image height is slightly higher than the preset height.

[0123] If, during the operation shown in Figures 10A to 10C, the light intensity value detected by either the first light sensor LS1 or the second light sensor LS2 decreases to below the low intensity threshold of 2000 Lux and remains below the second time threshold, it indicates that the risk of the display panel 21 being damaged by high temperature has been eliminated, and the concave mirror 4 can be rotated back to its initial angle. Conversely, if the light intensity value decreases, it indicates that the display panel 21 is still at risk of being damaged by high temperature. Then, the concave mirror 4 is rotated significantly upwards or downwards to a stopping angle to interrupt the phenomenon of sunlight SL flowing back onto the display panel 21, as shown in Figure 10D, so that sunlight SL no longer shines on the display panel 21. At this time, the path of image light D to the viewer is also interrupted, and the virtual image VI disappears.

[0124] When strong sunlight SL is backflowing, using the aforementioned procedure, when the two light sensors LS1 and LS2 detect sunlight SL of moderate to high intensity behind the reflector 3, the concave mirror 4 is rotated at an appropriate angle to cause a slight movement of the virtual image VI, prolonging the time the viewer sees the virtual image VI and reducing the frequency and duration of interruptions to the virtual image VI. At the same time, the position of the sunlight spot S_bsp on the display panel is changed to avoid continuous heating of the same area. If it is determined that sunlight SL is not shining on the display panel 21, the concave mirror 4 is returned to its initial angle. If there is still a risk, the light path is interrupted for cooling before the concave mirror 4 is returned to its initial angle.

[0125] As shown in Figure 11A, the concave mirror 4 is set at the middle angle of its rotation adjustment range, and strong sunlight SL flows back into the head-up display. The sunlight spot S_bsp on the display panel is in the upper half of the display panel 21. The first light sensor LS1 and the second light sensor LS2 are within the range of the sunlight spot S_bsr on the reflector, and both detect light intensity values ​​higher than the medium intensity threshold of 4000 Lux.

[0126] The greater the difference between the light intensity detected by the first light sensor LS1 and the light intensity detected by the second light sensor LS2 (e.g., the difference is greater than the high difference threshold of 4000 Lux), the closer the position of the sunlight spot S_bsp on the display panel is to the upper half of the display panel 21. At this time, the angle of the concave mirror 4 is the initial angle, and the image VI seen by the viewer is at the preset height.

[0127] If it is determined that the sunlight spot S_bsp on the display panel is in the upper half of the display panel 21, the concave mirror 4 can be rotated upwards, as shown in Figure 11B, so that the sunlight spot S_bsp on the display panel 21 moves upwards. This means that the direction of rotation of the concave mirror 4 is the direction in which the sunlight spot S_bsr on the reflector moves from the position of the reflector 3 towards the position of the first light sensor LS1. The first light sensor LS1 remains within the range of the sunlight spot S_bsr on the reflector and detects a light intensity value higher than the medium intensity threshold of 4000 Lux, or even higher than the high intensity threshold of 8000 Lux. The second light sensor LS2 leaves the range of the sunlight spot S_bsr on the reflector and detects a light intensity value lower than the low intensity threshold of 2000 Lux.

[0128] When the light intensity detected by the second light sensor LS2 is lower than the low intensity threshold of 2000 Lux, it means that the sunlight SL has moved upwards and is no longer shining on the display panel 21. At this time, the viewer can still see the virtual image VI, but the image height is slightly lower than the preset value.

[0129] As shown in Figure 12A, the concave mirror 4 is set at the middle angle of its rotation adjustment range, and strong sunlight SL flows back into the head-up display. The sunlight spot S_bsp on the display panel is in the lower half of the display panel 21. The first light sensor LS1 and the second light sensor LS2 are within the range of the sunlight spot S_bsr on the reflector, and both detect light intensity values ​​higher than the medium intensity threshold of 4000 Lux.

[0130] The greater the difference between the light intensity detected by the second light sensor LS2 and the light intensity detected by the first light sensor LS1 (e.g., the greater the difference is than the high difference threshold of 4000 Lux), the closer the position of the sunlight spot S_bsp on the display panel is to the lower half of the display panel 21. At this time, the angle of the concave mirror 4 is the initial angle, and the image VI seen by the viewer is at the preset height.

[0131] If it is determined that the sunlight spot S_bsp on the display panel is in the lower half of the display panel 21, the concave mirror 4 can be rotated downward from its current initial angle, as shown in Figure 12B. This moves the sunlight spot S_bsp on the display panel 21 downward. This means that the direction of rotation of the concave mirror 4 is the direction in which the sunlight spot S_bsr on the reflector moves from the position of the reflector 3 towards the location of the second light sensor LS2. This causes the first light sensor LS1 to move away from the range of the sunlight spot S_bsr on the reflector and detect a light intensity value lower than the low intensity threshold of 2000 Lux. The second light sensor LS2 remains within the range of the sunlight spot S_bsr on the reflector and detects a light intensity value higher than the medium intensity threshold of 4000 Lux, and even higher than the high intensity threshold of 8000 Lux.

[0132] When the light intensity detected by the first light sensor LS1 is lower than the low intensity threshold of 2000 Lux, it means that the sunlight SL has moved downwards and is no longer shining on the display panel 21. At this time, the viewer can still see the virtual image VI, which is slightly higher than the preset height.

[0133] The reflector 3 needs to reflect most of the image light D projected by the display panel 21, and also needs to allow sunlight SL to partially pass through the reflector 3 to the light sensor to detect the area and intensity of sunlight SL. In addition to using a glass substrate with a surface-plated silver reflective film, aluminum reflective film, gold reflective film, or dielectric reflective film, a reflective polarizer can also be used for the reflector 3. For example, a reflective polarizer can be attached to a transparent substrate so that polarized waves in one direction are reflected and polarized waves in the other direction are passed through, which can further reduce the damage of backflow sunlight to the display panel 21.

[0134] As shown in Figure 13A, the reflector 3 is a reflective polarizer 31, which can reflect most of the S-polarized waves and allow most of the P-polarized waves to pass through, with a transmittance of about 40-50%. The image light D projected by the display panel 21 is set as an S-polarized wave. Most of the projected S-polarized image light is reflected by the reflective polarizer 31 to the concave mirror 4. Finally, some of the S-polarized image light is reflected to the viewer's eyes on the windshield G, and the viewer sees a virtual image.

[0135] As shown in Figure 13B, sunlight contains P-polarized waves and S-polarized waves. The transmittance of P-polarized waves in the windshield G is higher than that of S-polarized waves. After the sunlight passes through the windshield G, it is reflected by the concave mirror 4 to the reflective polarizer 31. Most of the P-polarized waves pass through the reflective polarizer 31 and are provided to the light sensing module 5 to detect the sunlight-irradiated area and light intensity. Only the weaker S-polarized waves are reflected to the display panel 21, which can reduce the intensity of sunlight hitting the display panel 21 and slow down the rate at which the display panel 21 heats up when sunlight flows back in.

[0136] As shown in Figure 13C, a reflective polarizer 31 is used as a reflector 3. The intensity of the P-polarized wave that passes through the reflective polarizer 31 is relatively high. Some of the P-polarized wave will be reflected back by the circuit board 50 of the photosensitive module 5 and will pass through the reflective polarizer 31 a second time to enter the image projection light path. Finally, it will reach the viewer's eyes, allowing the viewer to see the light reflected by the photosensitive module 5, thus causing interference.

[0137] To prevent viewers from seeing the light reflected by the light sensing module 5, a light-reducing filter 6 can be placed between the reflective polarizer 31 and the light sensing module 5, as shown in Figure 13D. The light-reducing filter 6 attenuates the P-polarized light that passes through the reflective polarizer 31, and the remaining light that passes through then illuminates the light sensing module 5, providing the light sensing module 5 with information to detect the area and intensity of sunlight SL. Even if there is still light reflected by the light sensing module 5, it will be significantly attenuated when it passes through the light-reducing filter 6 a second time. Even if it can pass through the reflective polarizer 31 a second time, the remaining light intensity will be so low that it will not be noticeable to the viewer.

[0138] The characteristic of the neutral density filter 6 is that it absorbs most of the light and allows only a small portion of the light to pass through, for example, the attenuation rate is about 60~95%, and the surface reflectivity is low, for example, the reflectivity is less than 15%. Therefore, it can be made of natural fiber material, artificial fiber material, glass material or liquid crystal material.

[0139] The human eye has a certain degree of adaptability to brightness, which is formed by the adjustment of pupil size and changes in the photosensitive substances in the retina. Cone cells and rod cells perform different visual functions. Cone cells have low photosensitivity and function in brightness conditions above 3 cd / m², where they can distinguish colors and details of objects; this is called cone vision, also known as photopic vision. Rod cells, on the other hand, function only in dark conditions (brightness below 0.001 cd / m²); this is called rod vision, also known as scotopic vision.

[0140] At high brightness, the pupil constricts to prevent excessive light from entering the retina, and the cone cells responsible for photopic vision function. At low brightness, the pupil dilates to allow more light to enter the retina, and the rod cells responsible for scotopic vision function. If the brightness falls between the levels corresponding to photopic and scotopic vision, both cone and rod cells in the retina function simultaneously, a condition known as mesovision.

[0141] Over a fairly wide range of brightness, the minimum relative brightness change (ΔBmin / B) perceptible to the human eye is equal to a constant δ. This constant δ is called the contrast sensitivity threshold or the Weber-Fechner ratio. The contrast sensitivity threshold is related to the ambient light level and is typically in the range of 0.5% to 2%.

[0142] For two images with different background brightness, the brightness difference must be at least 0.5% to 2% for the human eye to distinguish the brightness difference. When the brightness is very high or very low, the contrast sensitivity threshold will increase to 5%.

[0143] In the high-brightness background of a head-up display under midday sunlight, the contrast sensitivity threshold of the human eye is about 2% to 5%. The background brightness when looking out the windshield from inside a car is about 2000 Lux to 12000 Lux. Based on the contrast sensitivity threshold of 2%, the human eye would need a brightness change of at least 40 Lux to 240 Lux to perceive it.

[0144] For example, when there is no light-reducing filter 6 behind the reflective polarizer 31, if the light sensor is located at the center of the sunlight spot S_bsr on the reflector, the measured light intensity value is about 50,000 Lux. About 25% is reflected back to the image projection light path. Due to the attenuation of the light path and the low reflectivity of the P-polarized wave on the windshield G, only about 5% is reflected on the windshield G. The intensity reaching the viewer's eye is about 625 Lux (=50,000 × 25% × 5%), which is higher than the contrast sensitivity threshold of the human eye under this brightness background condition. Therefore, the viewer can see the light sensing module 5.

[0145] When a neutral density filter 6 with an 80% attenuation rate is placed behind the reflective polarizer 31, the light sensor is located at the center of the sunlight spot S_bsr on the reflector and measures a light intensity of about 10,000 Lux. After reflection, only about 5% of the light passes through the neutral density filter and returns to the optical path. Due to the attenuation of the optical path and the low reflectivity of the P-polarized wave on the windshield, only about 5% of the light is reflected on the windshield, and the intensity reaching the viewer's eye is about 25 Lux (=10,000×5%×5%), which is lower than the contrast sensitivity threshold of the human eye under this brightness background condition. Therefore, the viewer will not see the light sensing module 5.

[0146] If the light sensor is located at the edge of the sunlight spot S_bsr on the reflector, the measured sunlight intensity value is about 6000 Lux, and the intensity reaching the viewer's eyes is about 15 Lux (=6000×5%×5%). The viewer will not be able to see the light sensor module 5.

[0147] The specific structure of the head-up display device has been described above, and it can detect backlighting using the following method. The light intensity values ​​detected by the first light sensor LS1 and the second light sensor LS2 are S1 and S2, respectively. When the sunlight intensity SL is low, or the angle of sunlight does not cause backlighting, the light intensity value detected by at least one light sensor LS1, LS2 will be lower than the low intensity threshold BL. Conversely, when the sunlight intensity SL is high and there is a risk of high-temperature damage, and the angle of sunlight will cause backlighting onto the display panel 21, as long as sunlight shines on the display panel 21, the light intensity values ​​detected by the light sensors LS1, LS2 will be higher than the medium intensity threshold BM. When one of the light sensors LS1, LS2 is located at the center of the sunlight spot S_bsr on the reflector 3, the detected light intensity value may even be higher than the high intensity threshold BH.

[0148] The operation method of the head-up display device in response to this situation of sunlight backflow is as follows: First, move the sunlight spot S_bsp on the display panel 21 upwards, and then move it downwards. That is, the first rotation direction of the concave mirror 4 is to move the sunlight spot S_bsr on the reflector 3 towards the location of the first light sensor LS1. The second rotation direction is to move towards the location of the second light sensor LS2. It also detects whether there is an angle that makes the light intensity value detected by at least one light sensor LS1 and LS2 lower than the low intensity threshold BL. If there is still a risk of high temperature, the concave mirror 4 is rotated to a parking angle (as shown in Figure 10D) to turn off the image function and cool down.

[0149] As shown in Figure 14A, the specific operation method is as follows:

[0150] Step 1411: Determine whether the light intensity values ​​S1 and S2 are both higher than the medium intensity threshold BM and whether their durations reach the first time threshold T_th1;

[0151] Step 1412: If the determination is yes, rotate the concave mirror 4 by an angle θ (i.e., the minimum angle θ).

[0152] Step 1413: Determine whether the light intensity values ​​S1 and S2 are lower than the low intensity threshold BL and the duration reaches the second time threshold T_th2. If yes, proceed to step 1417; otherwise, proceed to step 1414.

[0153] Step 1414: Rotate the concave mirror 4 in the opposite direction to the rotation direction in step 1412 by an angle of 2θ (i.e., twice the minimum angle θ). For example, if the first rotation of the concave mirror 4 in step 1412 was upward, then the second rotation of the concave mirror 4 in this step 1414 will be downward; if the first rotation of the concave mirror 4 in step 1412 was downward, then the second rotation of the concave mirror 4 in this step 1414 will be upward.

[0154] Step 1415: Determine whether the light intensity values ​​S1 and S2 are lower than the low intensity threshold BL and the duration reaches the second time threshold T_th2. If yes, proceed to step 1417; otherwise, proceed to step 1416.

[0155] Step 1416: Rotate the concave mirror 4 to the parking angle and maintain it for a closing time T_rs.

[0156] Step 1417: Rotate the concave mirror 4 to the initial angle.

[0157] Example 1 of the aforementioned operating method is provided here. The relevant parameters are set as follows: the light intensity value detected by the first photosensitive sensor LS1 is S1, and the light intensity value detected by the second photosensitive sensor LS2 is S2. The low intensity threshold BL is 2000 Lux, the medium intensity threshold BM is 4000 Lux; the first time threshold T_th1 is 30 seconds, the second time threshold T_th2 is 25 seconds, the off time T_rs is 35 seconds, and the θ angle is 0.3 degrees.

[0158] The scenario in Example 1 is as follows: A vehicle is driving on an open road on a sunny summer noon. Strong sunlight penetrates the windshield from above and flows back into the head-up display device. After being reflected and focused by the concave mirror 4 and the reflector 3, it shines on the central area of ​​the display panel 21.

[0159] The sequence of events in Example 1 is as follows: The head-up display device begins monitoring at time T1. Both light intensity values ​​S1 and S2 exceed the medium intensity threshold BM for a duration reaching the first time threshold T_th1. Therefore, at time T2, the concave mirror is rotated upwards by an angle θ. Next, the changes in light intensity values ​​S1 and S2 are continuously monitored. Neither S1 nor S2 falls below the low intensity threshold BL for a duration reaching the second time threshold T_th2. Therefore, at time T3, the concave mirror is rotated downwards by an angle 2θ. Subsequently, both light intensity values ​​S1 and S2 remain above the low intensity threshold BL for a duration reaching the second time threshold T_th2. Therefore, at time T4, the concave mirror 4 is rotated to the parking angle and maintained for a closing time T_rs. At time T5, the concave mirror 4 is rotated back to the initial angle.

[0160] In the foregoing description, time is uninterrupted; that is, the time difference between time point T1 and time point T2 is a first time threshold T_th1 (30 seconds), the time difference between time point T2 and time point T3 is a second time threshold T_th2 (25 seconds), the time difference between time point T3 and time point T4 is a second time threshold T_th2 (25 seconds), and the time difference between time point T4 and time point T5 is a shutdown time T_rs (35 seconds). The following embodiments are described in the same manner.

[0161] During the aforementioned process, viewers can see the image of the head-up display device except for the period between time points T4 and T5. The only difference is the height of the image. Furthermore, this process avoids damage to the display panel 21 due to high temperatures caused by sunlight backflow.

[0162] Example 2 of the aforementioned operating method is provided here, and the relevant parameters are set in the same way as in Example 1.

[0163] The scenario in Example 2 is as follows: A vehicle is driving on an open road on a sunny summer noon. Strong sunlight penetrates the windshield from above and flows back into the head-up display. After being reflected and focused by the concave mirror 4 and the reflector 3, it shines on the central area of ​​the display panel. 55 seconds later, the vehicle enters a long tunnel.

[0164] The sequence of events in Example 2 is as follows: The head-up display device begins monitoring at time T1. Both light intensity values ​​S1 and S2 exceed the medium intensity threshold BM for a duration reaching the first time threshold T_th1. Therefore, at time T2, the concave mirror is rotated upwards by an angle θ. Next, the changes in light intensity values ​​S1 and S2 are continuously monitored. Neither S1 nor S2 falls below the low intensity threshold BL for a duration reaching the second time threshold T_th2. Therefore, at time T3, the concave mirror is rotated downwards by an angle 2θ. At this point, the vehicle enters a long tunnel, and sunlight no longer shines back. Subsequently, both S1 and S2 fall below the low intensity threshold BL for a duration reaching the second time threshold T_th2. Therefore, at time T4, the concave mirror 4 is rotated back to its initial angle.

[0165] During the aforementioned process, the concave mirror 4 rotates twice to change the area illuminated by sunlight. Although the height of the image is slightly different, it ensures that the viewer can still see the image and prevents the display panel 21 from being damaged by high temperatures due to sunlight backflow.

[0166] When the first light sensor LS1 is located at the center of the sunlight spot S_bsr on the reflector 3, and the detected light intensity value is higher than the high intensity threshold BH, it can be determined that the sunlight spot S_bsp on the display panel is on the upper half of the display panel 21.

[0167] The operation method of the head-up display device to deal with this kind of backlighting situation is as follows: first, move the sunlight spot S_bsp on the display panel 21 upwards to prevent the sunlight from shining on the display panel 21. If sunlight SL is still detected shining on the display panel 21, then move the sunlight spot S_bsp downwards. If there is still a risk of high temperature, turn off the concave mirror 4 to cool it down.

[0168] As shown in Figure 14B, the specific operation method is as follows.

[0169] Step 1421: Determine whether the light intensity value S1 is higher than the high intensity threshold BH, and whether the light intensity value S2 is higher than the medium intensity threshold BM, and whether the duration reaches the first time threshold T_th1.

[0170] Step 1422: If the judgment is yes, rotate the concave mirror 4 upwards by an angle θ.

[0171] Step 1423: Determine whether the light intensity value S1 or the light intensity value S2 is lower than the low intensity threshold BL and the duration reaches the second time threshold T_th2. If yes, proceed to step 1427; otherwise, proceed to step 1424.

[0172] Step 1424: Rotate the concave mirror 4 downwards by an angle of 2θ.

[0173] Step 1425: Determine whether the light intensity value S1 or S2 is lower than the low intensity threshold BL and the duration reaches the second time threshold T_th2. If yes, proceed to step 1427; otherwise, proceed to step 1426.

[0174] Step 1426: Rotate the concave mirror 4 to the parking angle and keep it closed for a time T_rs.

[0175] Step 1427: Rotate the concave mirror 4 to the initial angle.

[0176] When the second light sensor LS2 is located at the center of the sunlight spot S_bsr on the reflector 3, and the detected light intensity value is higher than the high intensity threshold BH, it can be determined that the sunlight spot S_bsp on the display panel is in the lower half of the display panel 21.

[0177] The operation method of the head-up display device to deal with this kind of backlighting situation is as follows: first, move the sunlight spot S_bsp on the display panel 21 downwards so that the sunlight no longer shines on the display panel 21. If sunlight SL is still detected shining on the display panel 21, then move the sunlight spot S_bsp on the display panel upwards. If there is still a risk of high temperature, turn off the concave mirror 4 to cool it down.

[0178] As shown in Figure 14C, the specific operation method is as follows.

[0179] Step 1431: Determine whether the light intensity value S2 is higher than the high intensity threshold BH, and whether the light intensity value S1 is higher than the medium intensity threshold BM, and whether the duration reaches the first time threshold T_th1.

[0180] Step 1432: If the determination is yes, rotate the concave mirror downwards by an angle θ.

[0181] Step 1433: Determine whether the light intensity value S1 or the light intensity value S2 is lower than the low intensity threshold BL and the duration reaches the second time threshold T_th2. If yes, proceed to step 1437; otherwise, proceed to step 1434.

[0182] Step 1434: Rotate the concave mirror 4 upwards by an angle of 2θ.

[0183] Step 1435: Determine whether the light intensity value S1 or S2 is lower than the low intensity threshold BL and the duration reaches the second time threshold T_th2. If yes, proceed to step 1437; otherwise, proceed to step 1436.

[0184] Step 1436: Rotate the concave mirror 4 to the parking angle and keep it closed for a time T_rs.

[0185] Step 1437: Rotate the concave mirror 4 to the initial angle.

[0186] Example 3 of the aforementioned operating method is provided here, and the relevant parameters are set in the same way as in Example 1.

[0187] The scenario in Example 3 is as follows: For example, a vehicle is driving on an open road on a sunny summer noon. Strong sunlight penetrates the windshield from above and flows back into the head-up display. After being reflected and focused by the concave mirror 4 and the reflector 3, it shines on the lower half of the display panel 21.

[0188] The sequence of events in Example 3 is as follows: The head-up display device begins monitoring at time T1. The light intensity value S2 exceeds the high intensity threshold BH, and the light intensity value S1 exceeds the medium intensity threshold BM. The duration of these values ​​reaches the first time threshold T_th1. Therefore, at time T2, the concave mirror is rotated downwards by an angle θ. Subsequently, the light intensity value S1 falls below the low intensity threshold BL, and the duration of this value reaches the second time threshold T_th2. Therefore, at time T3, the concave mirror is rotated back to its initial angle.

[0189] During this process, viewers can see the image on the head-up display, with only a slight difference in image height, and the display panel is protected from damage due to high temperatures caused by sunlight streaming in.

[0190] As mentioned above, the light intensity values ​​S1 and S2 detected by the light sensors LS1 and LS2 can be directly compared with the high intensity threshold BH and the medium intensity threshold BM to determine the position of sunlight shining on the display panel 21. The present invention can also use the difference between the aforementioned light intensity values ​​S1 and S2 to determine the area of ​​sunlight SL shining on the display panel 21.

[0191] A low difference threshold BDL and a high difference threshold BDH are preset.

[0192] If the light intensity values ​​S1 and S2 are both higher than the medium intensity threshold BM, and their difference is less than the low difference threshold BDL, it means that the center of the sunlight spot S_bsr of the reflector 3 is closer to the center between the two light sensors, that is, the position of the sunlight spot S_bsp of the display panel is in the central area of ​​the display panel 21.

[0193] The solution to this situation is to first move the sunlight spot S_bsp on the display panel 21 upwards and then downwards to detect if there is an angle that allows the light intensity value of at least one light sensor to be lower than the low intensity threshold BL. If there is still a risk of high temperature, then turn off the concave mirror 4 to cool it down.

[0194] The specific operating method is shown in Figure 15A.

[0195] Step 1511: Determine whether the light intensity values ​​S1 and S2 are both higher than the medium intensity threshold BM, and whether their difference is less than the low difference threshold BDL, and whether the duration reaches the first time threshold T_th1.

[0196] Step 1512: If the judgment is yes, rotate the concave mirror 4 upwards by an angle θ.

[0197] Step 1513: Determine whether the light intensity value S1 or the light intensity value S2 is lower than the low intensity threshold BL and the duration reaches the second time threshold T_th2. If yes, proceed to step 1517; otherwise, proceed to step 1514.

[0198] Step 1514: Rotate the concave mirror 4 downwards by an angle of 2θ.

[0199] Step 1515: Determine whether the light intensity value S1 or S2 is lower than the low intensity threshold BL and the duration reaches the second time threshold T_th2. If yes, proceed to step 1517; otherwise, proceed to step 1516.

[0200] Step 1516: Rotate the concave mirror 4 to the parking angle and keep it closed for a duration of T_rs.

[0201] Step 1517: Rotate the concave mirror 4 to the initial angle.

[0202] Example 4 of the aforementioned operating method is described below. The relevant parameters are set as follows: the light intensity value detected by the first photosensitive sensor LS1 is S1, and the light intensity value detected by the second photosensitive sensor LS2 is S2. The low intensity threshold BL is 2000 Lux, and the medium intensity threshold BM is 4000 Lux. The low difference threshold BDL is 1000 Lux, and the high difference threshold BDH is 4000 Lux. The first time threshold T_th1 is 30 seconds, the second time threshold T_th2 is 25 seconds, and the off time T_rs is 35 seconds. The angle θ is 0.3 degrees.

[0203] The scenario in Example 4 is as follows: A vehicle is driving on an open road on a sunny summer noon. Strong sunlight penetrates the windshield from above and flows back into the head-up display. After being reflected and focused by the concave mirror 4 and the reflector 3, the sunlight shines on the central area of ​​the display panel 21.

[0204] The procedure to handle this situation is as follows: Monitoring begins at time T1. Both light intensity values ​​S1 and S2 exceed the medium intensity threshold BM, and their difference is less than the low difference threshold BDL, with the duration reaching the first time threshold T_th1. Therefore, at time T2, the concave mirror is rotated upwards by an angle θ. Next, neither light intensity value S1 nor S2 falls below the low intensity threshold BL, and the duration reaches the second time threshold T_th2. Therefore, at time T3, the concave mirror is rotated downwards by an angle 2θ. Next, neither light intensity value S1 nor S2 falls below the low intensity threshold BL, and the duration reaches the second time threshold T_th2. Therefore, at time T4, the concave mirror 4 is rotated to the stopping angle and remains closed for a time T_rs. At time T5, the concave mirror 4 is rotated back to the initial angle.

[0205] During this process, viewers can see the image on the head-up display except for the period from time T4 to time T5. The only difference is the height of the image. This also avoids damage to the display panel due to high temperatures caused by sunlight backflow.

[0206] If the light intensity values ​​S1 and S2 detected by the two light sensors LS1 and LS2 are both higher than the medium intensity threshold BM, and the light intensity value S1 is greater than the light intensity value S2, and the difference between the two is greater than the high difference threshold BDH, this means that the center of the sunlight spot S_bsr of the reflector 3 is closer to the first light sensor LS1, that is, the position of the sunlight spot S_bsp of the display panel is in the upper half of the display panel 21.

[0207] The solution to this situation is to first move the sunlight spot S_bsp on the display panel 21 upwards, that is, to rotate the concave mirror 4 in the direction that moves the sunlight spot S_bsr on the reflector 3 toward the location of the first light sensor LS1, so that it no longer shines on the display panel 21. If sunlight SL still shines on the display panel 21, then move the sunlight spot S_bsp downwards. If there is still a risk of high temperature, then turn off the concave mirror 4 to cool it down.

[0208] The specific operating method is shown in Figure 15B.

[0209] Step 1521: Determine whether both light intensity values ​​S1 and S2 are higher than the medium intensity threshold BM, light intensity value S1 is greater than light intensity value S2, and the difference between the two is greater than the high difference threshold BDH, and the duration reaches the first time threshold T_th1.

[0210] Step 1522: If the determination is yes, rotate the concave mirror upwards by an angle θ.

[0211] Step 1523: Determine whether the light intensity value S1 or the light intensity value S2 is lower than the low intensity threshold BL and the duration reaches the second time threshold T_th2. If yes, proceed to step 1527; otherwise, proceed to step 1524.

[0212] Step 1524: Rotate the concave mirror 4 downwards by an angle of 2θ.

[0213] Step 1525: Determine whether the light intensity value S1 or the light intensity value S2 is lower than the low intensity threshold BL and the duration reaches the second time threshold T_th2. If yes, proceed to step 1527; otherwise, proceed to step 1526.

[0214] Step 1526: Rotate the concave mirror 4 to the parking angle and keep it closed for a duration of T_rs.

[0215] Step 1527: Rotate the concave mirror 4 to the initial angle.

[0216] If the light intensity values ​​S1 and S2 detected by the two light sensors LS1 and LS2 are both higher than the medium intensity threshold BM, and the light intensity value S2 is greater than the light intensity value S1, and the difference between the two is greater than the high difference threshold BDH, this means that the center of the sunlight spot S_bsr of the reflector 3 is closer to the second light sensor LS2, that is, the position of the sunlight spot S_bsp of the display panel is in the lower half of the display panel 21.

[0217] The solution to this situation is to first move the sunlight spot S_bsp on the display panel 21 downwards, that is, to rotate the concave mirror 4 in the direction that moves the sunlight spot S_bsr on the reflector from the position of the reflector 3 towards the position of the second light sensor LS2, so that it no longer shines on the display panel 21. If sunlight SL still shines on the display panel 21, then move the sunlight spot S_bsp on the display panel upwards. If there is still a risk of high temperature, then turn off the concave mirror to cool it down.

[0218] The specific operating method is shown in Figure 15C.

[0219] Step 1531: Determine whether both light intensity values ​​S1 and S2 are higher than the medium intensity threshold BM, light intensity value S2 is greater than light intensity value S1, and the difference between the two is greater than the high difference threshold BDH, and the duration reaches the first time threshold T_th1.

[0220] Step 1532: If the determination is yes, rotate the concave mirror downwards by an angle θ.

[0221] Step 1533: Determine whether the light intensity value S1 or the light intensity value S2 is lower than the low intensity threshold BL and remains below the second time threshold T_th2. If yes, proceed to step 1537; otherwise, proceed to step 1534.

[0222] Step 1534: Rotate the concave mirror 4 upwards by an angle of 2θ.

[0223] Step 1535: Determine whether the light intensity value S1 or the light intensity value S2 is lower than the low intensity threshold BL and the duration reaches the second time threshold T_th2. If yes, proceed to step 1537; otherwise, proceed to step 1536.

[0224] Step 1536: Rotate the concave mirror 4 to the parking angle and keep it closed for a duration of T_rs.

[0225] Step 1527: Rotate the concave mirror 4 to the initial angle.

[0226] Example 5 of the aforementioned operating method is described below. The relevant parameter settings for Example 5 are the same as those for Example 4.

[0227] The scenario in Example 5 is as follows: A vehicle is driving on an open road on a sunny summer noon. Strong sunlight penetrates the windshield from above and flows back into the head-up display. After being reflected and focused by the concave mirror 4 and the reflector 3, it shines on the lower half of the display panel.

[0228] The procedure to handle this situation is as follows: Monitoring begins at time T1. Both light intensity values ​​S1 and S2 exceed the medium intensity threshold BM, and light intensity value S2 is greater than light intensity value S1. The difference between the two exceeds the high difference threshold BDH, and the duration reaches the first time threshold T_th1. Therefore, at time T2, the concave mirror is rotated downwards by an angle θ. Next, neither light intensity value S1 nor S2 falls below the low intensity threshold BL, and the duration reaches the second time threshold T_th2. Therefore, at time T3, the concave mirror 4 is rotated upwards by an angle 2θ. Next, neither light intensity value S1 nor S2 falls below the low intensity threshold BL, and the duration reaches the second time threshold T_th2. Therefore, at time T4, the concave mirror 4 is rotated to the stopping angle and remains closed for a time T_rs. At time T5, the concave mirror is rotated back to the initial angle.

[0229] During this process, viewers can see the image on the head-up display except for the period from time T4 to time T5. The only difference is the height of the image. This also avoids damage to the display panel due to high temperatures caused by sunlight backflow.

[0230] Generally, display panels are mostly wider horizontally and narrower vertically. Therefore, when sunlight does not shine from above, but rather from the left or right, it shines back into the head-up display, illuminating the sides of the display panel. In this case, if only the first light sensor LS1 and the second light sensor LS2 are present, they may detect a moderate light intensity value and mistakenly interpret it as sunlight shining on the center of the display panel. However, in reality, the sunlight is shining on the outer left or right edge of the display panel 21, not directly onto the display panel. Furthermore, concave mirrors 4 are mostly freeform mirrors, and after off-axis reflection, the actual area illuminated by sunlight is not as perfect as theoretically possible, resulting in a discrepancy between the detected signal intensity and the actual intensity.

[0231] In order to more accurately detect and determine the area of ​​sunlight, quickly prevent sunlight from shining on the display panel, reduce the risk of high temperature damage, and reduce the frequency of light path interruption, in addition to setting the first light sensor LS1 and the second light sensor LS2 in the upper and lower halves of the reflector 3 as previously described, a third light sensor LS3 and a fourth light sensor LS4 can also be added in the left and right halves of the reflector 3.

[0232] As shown in Figure 16A, when the concave mirror 4 is set at the middle angle of its rotation adjustment range, and sunlight SL shines on the outer side of the lower edge of the display panel 21, the first light sensor LS1 is set on the outer side of the upper edge of the sunlight spot S_bsr of the reflector 3 at this time;

[0233] As shown in Figure 16B, when the concave mirror 4 is set at the middle angle of its rotation adjustment range, and sunlight SL shines on the outer edge of the upper edge of the display panel 21, the second light sensor LS2 is set on the outer edge of the lower edge of the sunlight spot S_bsr of the reflector 3 at this time;

[0234] As shown in Figure 16C, when the concave mirror 4 is set at the middle angle of its rotation adjustment range, and sunlight SL shines on the outer left edge of the display panel 21, the third light sensor LS3 is set on the outer left edge of the sunlight spot S_bsr of the reflector 3 at this time;

[0235] As shown in Figure 16D, when the concave mirror 4 is set at the middle angle of its rotation adjustment range, and the sunlight SL shines on the outer right edge of the display panel 21, the fourth light sensor LS4 is set on the outer right edge of the sunlight spot S_bsr of the reflector 3 at this time.

[0236] The light intensities detected by the light sensors LS1, LS2, LS3, and LS4 are the light intensity values ​​S1, S2, S3, and S4, respectively. Furthermore, high light intensity is denoted as H, medium light intensity as M, and low light intensity as L.

[0237] As shown in Figure 17, the sunlight spot S_bsp on the display panel 21 will appear in different positions, and each position will correspond to the position of the sunlight spot S_bsr on the reflector 3.

[0238] Based on the nine scenarios (numbers 17-1 to 17-9) shown in Figure 17, the light intensity values ​​S1, S2, S3, and S4 detected by the light sensors LS1, LS2, LS3, and LS4 are classified as high, medium, and low light intensities, and the results are shown in Table 1.

[0239] Table 1 Light intensity value Number S1 S2 S3 S4 17-1 M M M M 17-2 H M M M 17-3 M H M M 17-4 M M H M 17-5 M M M H 17-6 H M H M 17-7 M H H M 17-8 M H M H 17-9 H M M H

[0240] As shown in Figure 18, if sunlight SL does not shine on display panel 21, at least one light sensor is outside the range of sunlight spot S_bsr on reflector 3.

[0241] At this point, based on the eight scenarios (numbers 18-1 to 18-8) shown in Figure 18, the light intensity values ​​S1, S2, S3, and S4 detected by the four light sensors LS1, LS2, LS3, and LS4 are classified as high, medium, and low light intensities, as shown in Table 2.

[0242] Table 2 Light intensity value Number S1 S2 S3 S4 18-1 H L M M 18-2 L H M M 18-3 M M H L 18-4 M M L H 18-5 M L M L 18-6 L M M L 18-7 L M L M 18-8 M L L M

[0243] When the intensity of sunlight SL is low, or when there is no backflow of sunlight, at least one photosensitive sensor will detect a light intensity value lower than the low intensity threshold BL. When the intensity of sunlight SL is high and backflow of sunlight occurs, the light intensity values ​​S1, S2, S3, and S4 on the display panel 21 are all higher than the medium intensity threshold BM. If one of the photosensitive sensors is located at the center of the sunlight spot S_bsr on the reflector of the reflector 3, the light intensity value it detects will be higher than the high intensity threshold BH.

[0244] The operation method in this case is to first move the sunlight spot S_bsp on the display panel 21 upward or downward, and then move it in the opposite direction (downward or upward) to detect whether there is an angle that allows the light intensity value of at least one light sensor to be lower than the low intensity threshold BL. If there is still a risk of high temperature, the concave mirror 4 is turned off to cool it down.

[0245] The specific operating method is shown in Figure 19A.

[0246] Step 1911: Determine whether the light intensity values ​​S1, S2, S3 and S4 are all higher than the medium intensity threshold BM and the duration reaches the first time threshold T_th1.

[0247] Step 1912: Rotate the concave mirror 4 upwards by an angle θ.

[0248] Step 1913: Determine whether the light intensity value S1, S2, S3, or S4 is lower than the low intensity threshold BL and the duration reaches the second time threshold T_th2. If yes, proceed to step 1917; otherwise, proceed to step 1914.

[0249] Step 1914: Rotate the concave mirror 4 downwards by an angle of 2θ.

[0250] Step 1915: Determine whether the light intensity value S1, S2, S3, or S4 is lower than the low intensity threshold BL and the duration reaches the second time threshold T_th2. If yes, proceed to step 1917; otherwise, proceed to step 1916.

[0251] Step 1916: Rotate the concave mirror 4 to the parking angle and keep it closed for a duration of T_rs.

[0252] Step 1917: Rotate the concave mirror 4 to the initial angle.

[0253] The effect can be achieved as long as the direction of the first rotation of the concave mirror 4 is opposite to the direction of the second rotation; it is not limited to rotating it upwards first and then downwards.

[0254] Embodiment 6 of the aforementioned operating method is provided here, with the relevant parameters set as follows: the light intensity values ​​detected by the first light sensor LS1 to the fourth light sensor LS4 are S1, S2, S3, and S4, respectively. The low intensity threshold BL is 2000 Lux, the medium intensity threshold BM is 4000 Lux, the low difference threshold BDL is 1000 Lux, and the high difference threshold BDH is 4000 Lux. The first time threshold T_th1 is 30 seconds, the second time threshold T_th2 is 25 seconds, and the off time is, for example, 35 seconds. The θ angle is 0.3 degrees.

[0255] The scenario in Example 6 is as follows: A vehicle is driving on an open road on a sunny summer noon. Strong sunlight penetrates the windshield from above and flows back into the head-up display. After being reflected and focused by the concave mirror 4 and the reflector 3, the sunlight shines on the lower right corner of the display panel 21.

[0256] The procedure to handle this situation is as follows: Monitoring begins at time T1. The light intensity values ​​S1, S2, S3, and S4 all exceed the medium intensity threshold BM, and the duration reaches the first time threshold T_th1. Therefore, at time T2, the concave mirror 4 is rotated upwards by an angle θ. Next, the light intensity values ​​S1, S2, S3, or S4 do not fall below the low intensity threshold BL, and the duration reaches the second time threshold T_th2. Therefore, at time T3, the concave mirror 4 is rotated downwards by an angle 2θ. Next, the light intensity value S4 falls below the low intensity threshold BL, and the duration reaches the second time threshold T_th2. Therefore, at time T4, the concave mirror is rotated back to its initial angle.

[0257] During this process, viewers can see the image on the head-up display, with only a slight difference in image height, and the display panel is protected from damage due to high temperatures caused by sunlight streaming in.

[0258] When the light intensity value S1 of the first light sensor LS1 is higher than the high intensity threshold BH, it can be determined that the sunlight is biased towards the upper half of the display panel 21. Therefore, the sunlight spot S_bsp on the display panel 21 can be moved upwards to prevent the sunlight SL from shining on the display panel 21. If it is detected that the sunlight SL is still shining on the display panel 21, the sunlight spot S_bsp on the display panel can be moved downwards. If there is still a risk of high temperature, the concave mirror 4 can be turned off to cool down.

[0259] The specific operating method is shown in Figure 19B.

[0260] Step 1921: Determine whether the light intensity value S1 is higher than the high intensity threshold BH, and whether the light intensity values ​​S2, S3, and S4 are all higher than the medium intensity threshold BM, and whether the duration reaches the first time threshold T_th1.

[0261] Step 1922: If the judgment is yes, rotate the concave mirror 4 upwards by an angle θ.

[0262] Step 1923: Determine whether the light intensity value S1, S2, S3, or S4 is lower than the low intensity threshold BL and the duration reaches the second time threshold T_th2. If yes, proceed to step 1927; otherwise, proceed to step 1924.

[0263] Step 1924: Rotate the concave mirror 4 downwards by an angle of 2θ.

[0264] Step 1925: Determine whether the light intensity value S1, S2, S3, or S4 is lower than the low intensity threshold BL and the duration reaches the second time threshold T_th2. If yes, proceed to step 1927; otherwise, proceed to step 1926.

[0265] Step 1926: Rotate the concave mirror 4 to the parking angle and keep it closed for a duration of T_rs.

[0266] Step 1927: Rotate the concave mirror 4 to the initial angle.

[0267] When the light intensity value S2 of the second light sensor LS2 is higher than the high intensity threshold BH, it can be determined that the sunlight is biased towards the lower half of the display panel 21. Therefore, the sunlight spot S_bsp on the display panel 21 can be moved downwards to prevent the sunlight SL from shining on the display panel 21. If it is detected that the sunlight SL is still shining on the display panel 21, the sunlight spot S_bsp on the display panel can be moved upwards. If there is still a risk of high temperature, the concave mirror 4 can be turned off to cool down.

[0268] The specific operating method is shown in Figure 19C.

[0269] Step 1931: Determine whether the light intensity value S2 is higher than the high intensity threshold BH, and whether the light intensity values ​​S1, S3, and S4 are all higher than the medium intensity threshold BM, and whether the duration reaches the first time threshold T_th1.

[0270] Step 1932: If the judgment is yes, rotate the concave mirror 4 downwards by an angle θ.

[0271] Step 1933: Determine whether the light intensity value S1, S2, S3, or S4 is lower than the low intensity threshold BL and the duration reaches the second time threshold T_th2. If yes, proceed to step 1937; otherwise, proceed to step 1934.

[0272] Step 1934: Rotate the concave mirror 4 upwards by an angle of 2θ.

[0273] Step 1935: Determine whether the light intensity value S1, S2, S3, or S4 is lower than the low intensity threshold BL and the duration reaches the second time threshold T_th2. If yes, proceed to step 1937; otherwise, proceed to step 1936.

[0274] Step 1936: Rotate the concave mirror 4 to the parking angle and keep it closed for a duration of T_rs.

[0275] Step 1937: Rotate the concave mirror 4 to the initial angle.

[0276] An embodiment 7 is provided for the aforementioned operating method, wherein the relevant parameters are set to be the same as those in embodiment 6, and the high-intensity threshold BH is increased to 8000 Lux.

[0277] The scenario in Example 7 is as follows: A vehicle is driving on an open road on a sunny summer noon. Strong sunlight penetrates the windshield from above and flows back into the head-up display. After being reflected and focused by the concave mirror 4 and the reflector 3, the sunlight shines on the lower right corner of the display panel 21.

[0278] The procedure to handle this situation is as follows: Monitoring begins at time T1. The light intensity value S2 exceeds the high-intensity threshold BH, and light intensity values ​​S1, S3, and S4 all exceed the medium-intensity threshold BM for a duration reaching the first time threshold T_th1. Therefore, at time T2, the concave mirror 4 is rotated downwards by an angle θ. Subsequently, the light intensity values ​​S1 and S4 both fall below the low-intensity threshold BL for a duration reaching the second time threshold T_th2 (25 seconds). Therefore, at time T3, the concave mirror 4 is rotated back to its initial angle.

[0279] During this process, viewers can see the image on the head-up display, with only a slight difference in image height, and the display panel is protected from damage due to high temperatures caused by sunlight streaming in.

[0280] The four light sensors can also be arranged in different distributions, for example, the first light sensor is in the upper left corner, the second light sensor is in the upper right corner, the third light sensor is in the lower right corner, and the fourth light sensor is in the lower left corner.

[0281] As shown in Figure 20A, when the concave mirror 4 is set at the middle angle of its rotation adjustment range, and the sunlight SL shines on the outer edge of the lower left corner of the display panel 21, the first light sensor LS1 is set on the outer edge of the upper left corner of the sunlight spot S_bsr of the reflector 3 at this time;

[0282] As shown in Figure 20B, when the concave mirror 4 is set at the middle angle of its rotation adjustment range, and the sunlight SL shines on the outer edge of the lower right corner of the display panel 21, the second light sensor LS2 is set on the outer edge of the upper right corner of the sunlight spot S_bsr of the reflector 3 at this time;

[0283] As shown in Figure 20C, when the concave mirror 4 is set at the middle angle of its rotation adjustment range, and the sunlight SL shines on the outer edge of the upper right corner of the display panel 21, the third light sensor LS3 is set on the outer edge of the lower right corner of the sunlight spot S_bsr of the reflector 3 at this time;

[0284] As shown in Figure 20D, when the concave mirror 4 is set at the middle angle of its rotation adjustment range, and the sunlight SL shines on the outer edge of the upper left corner of the display panel 21, the fourth light sensor LS4 is set on the outer edge of the lower left corner of the sunlight spot S_bsr of the reflector 3 at this time.

[0285] The light intensities detected by the light sensors LS1, LS2, LS3, and LS4 are the light intensity values ​​S1, S2, S3, and S4, respectively. Furthermore, high light intensity is denoted as H, medium light intensity as M, and low light intensity as L.

[0286] As shown in Figure 21, the sunlight spot S_bsp on the display panel 21 will appear in different positions, and each position will correspond to the position of the sunlight spot S_bsr on the reflector 3.

[0287] Based on the nine scenarios (numbers 21-1 to 21-9) shown in Figure 21, the light intensity values ​​S1, S2, S3, and S4 detected by the light sensors LS1, LS2, LS3, and LS4 are classified as high, medium, and low light intensities, and the results are shown in Table 3.

[0288] Table 3 Light intensity value Number S1 S2 S3 S4 21-1 M M M M 21-2 M M M M 21-3 M M M M 21-4 M M M M 21-5 M M M M 21-6 H M M M 21-7 M M M H 21-8 M M H M 21-9 M H M M

[0289] As shown in Figure 22, if sunlight SL does not shine on display panel 21, at least one light sensor is outside the range of sunlight spot S_bsr on reflector 3. At this time, the light intensity values ​​S1, S2, S3, and S4 detected by the four light sensors LS1, LS2, LS3, and LS4 are classified as high, medium, and low light intensities, respectively, as shown in Table 4.

[0290] Table 4 Light intensity value Number S1 S2 S3 S4 22-1 M M L L 22-2 L L M M 22-3 M L L M 22-4 L M M L 22-5 M L L L 22-6 L L L M 22-7 L L M L 22-8 L M L L

[0291] When sunlight SL shines on the outer edges of the four corners of the display panel 21, four light sensors are respectively positioned on the outer edges of the four corners of the sunlight spot S_bsr on the reflector 3. When the intensity of sunlight SL is low, or when the angle of illumination does not cause sunlight backflow, at least one light sensor will detect a light intensity value lower than the low intensity threshold BL. When the intensity of sunlight SL is high and sunlight backflow occurs, as long as sunlight shines on the display panel 21, the light intensity values ​​of all four light sensors will be higher than the medium intensity threshold BM. If one of the light sensors is located at the center of the sunlight spot S_bsr on the reflector 3, its detected light intensity value will be higher than the high intensity threshold BH.

[0292] The operation method for this situation is to move the sunlight spot S_bsp on the display panel 21 upwards and then downwards. That is, the direction of the concave mirror 4 rotation is to move the sunlight spot S_bsr of the reflector from the position of the reflector 3 towards the location of the first light sensor LS1 and the second light sensor LS2, and then towards the location of the third light sensor LS3 and the fourth light sensor LS4. Detect whether there is an angle that allows the light intensity value of at least one light sensor to be lower than the low intensity threshold BL. If there is still a risk of high temperature, turn off the concave mirror 4 to cool it down.

[0293] The specific operating method is shown in Figure 23A.

[0294] Step 2311: Determine whether the light intensity values ​​S1, S2, S3 and S4 are all higher than the medium intensity threshold BM, and whether their durations reach the first time threshold T_th1.

[0295] Step 2312: If the judgment is yes, rotate the concave mirror 4 upward by an angle θ.

[0296] Step 2313: Determine whether the light intensity value S1, S2, S3, or S4 is lower than the low intensity threshold BL and the duration reaches the second time threshold T_th2. If yes, proceed to step 2317; otherwise, proceed to step 2314.

[0297] Step 2314: Rotate the concave mirror 4 downwards by an angle of 2θ.

[0298] Step 2315: Determine whether the light intensity value S1, S2, S3, or S4 is lower than the low intensity threshold BL and the duration reaches the second time threshold T_th2. If yes, proceed to step 2317; otherwise, proceed to step 2316.

[0299] Step 2316: Rotate the concave mirror 4 to the parking angle and keep it closed for a time T_rs.

[0300] Step 2317: Rotate the concave mirror 4 to the initial angle.

[0301] If the concave mirror 4 is rotated upwards the first time, then the concave mirror 4 will be rotated downwards the second time. Alternatively, the concave mirror 4 can be rotated downwards the first time and upwards the second time.

[0302] An embodiment 8 is provided for the aforementioned operating method, wherein the relevant parameters are set as follows: the light intensity values ​​detected by the first light sensor LS1 to the fourth light sensor LS4 are S1, S2, S3 and S4, respectively. The low intensity threshold BL is 2000 Lux, the medium intensity threshold BM is 4000 Lux. The low difference threshold BDL is 1000 Lux, and the high difference threshold BDH is 4000 Lux. The first time threshold T_th1 is 30 sec, the second time threshold T_th2 is 25 sec, and the off time is, for example, 35 sec. The θ angle is 0.3 degrees.

[0303] The scenario in Example 8 is as follows: A vehicle is driving on an open road on a sunny summer noon. Strong sunlight penetrates the windshield from above and flows back into the head-up display. After being reflected and focused by the concave mirror 4 and the reflector 3, the sunlight shines on the lower right corner of the display panel 21.

[0304] The procedure to handle this situation is as follows: Monitoring begins at time T1. The light intensity values ​​S1, S2, S3, and S4 all exceed the medium intensity threshold BM, and the duration reaches the first time threshold T_th1. Therefore, at time T2, the concave mirror 4 is rotated upwards by an angle θ. Next, the light intensity values ​​S1, S2, S3, or S4 are not lower than the low intensity threshold BL, and the duration reaches the second time threshold T_th2. Therefore, at time T3, the concave mirror 4 is rotated downwards by an angle 2θ. Next, the light intensity values ​​S1 and S2 are both lower than the low intensity threshold BL, and the duration reaches the second time threshold T_th2. Therefore, at time T4, the concave mirror 4 is rotated back to its initial angle.

[0305] During this process, viewers can see the image on the head-up display, with only a slight difference in image height, and the display panel is protected from damage due to high temperatures caused by sunlight streaming in.

[0306] When the light intensity values ​​S1 and S2 of the first light sensor LS1 or the second light sensor LS2 are higher than the high intensity threshold BH, it can be determined that the sunlight is biased towards the upper half of the display panel 21. Therefore, the sunlight spot S_bsp on the display panel 21 can be moved upwards to prevent the sunlight from shining on the display panel 21. If sunlight SL is still detected shining on the display panel 21, the sunlight spot S_bsp on the display panel can be moved downwards. If there is still a risk of high temperature, the concave mirror 4 can be turned off to cool it down.

[0307] The specific operating method is shown in Figure 23B.

[0308] Step 2321: Determine whether the light intensity value S1 or S2 is higher than the high intensity threshold BH, and whether the light intensity values ​​S1, S2, S3, and S4 are all higher than the medium intensity threshold BM, and whether the duration reaches the first time threshold T_th1.

[0309] Step 2322: If the judgment is yes, rotate the concave mirror 4 upwards by an angle θ.

[0310] Step 2323: Determine whether the light intensity value S1, S2, S3, or S4 is lower than the low intensity threshold BL and the duration reaches the second time threshold T_th2. If yes, proceed to step 2327; otherwise, proceed to step 2324.

[0311] Step 2324: Rotate the concave mirror 4 downwards by an angle of 2θ.

[0312] Step 2325: Determine whether the light intensity value S1, S2, S3, or S4 is lower than the low intensity threshold BL and the duration reaches the second time threshold T_th2. If yes, proceed to step 2327; otherwise, proceed to step 2326.

[0313] Step 2326: Rotate the concave mirror 4 to the parking angle and keep it closed for a duration of T_rs.

[0314] Step 2327: Rotate the concave mirror 4 to the initial angle.

[0315] When the light intensity values ​​S3 and S4 of the third light sensor LS3 or the fourth light sensor LS4 are higher than the high intensity threshold BH, it can be determined that the sunlight is biased towards the lower half of the display panel 21. Therefore, the sunlight spot S_bsp on the display panel 21 can be moved downwards to prevent the sunlight from shining on the display panel 21. If sunlight SL is still detected shining on the display panel 21, the sunlight spot S_bsp on the display panel can be moved upwards. If there is still a risk of high temperature, the concave mirror 4 can be turned off to cool it down.

[0316] The specific operation is shown in Figure 23C.

[0317] Step 2331: Determine whether the light intensity value S3 or S4 is higher than the high intensity threshold BH, and whether the light intensity values ​​S1, S2, S3, and S4 are all higher than the medium intensity threshold BM, and whether the duration reaches the first time threshold T_th1.

[0318] Step 2332: If the judgment is yes, rotate the concave mirror 4 downwards by an angle θ.

[0319] Step 2333: Determine whether the light intensity value S1, S2, S3, or S4 is lower than the low intensity threshold BL and the duration reaches the second time threshold T_th2. If yes, proceed to step 2337; otherwise, proceed to step 2334.

[0320] Step 2334: Rotate the concave mirror 4 upwards by an angle of 2θ.

[0321] Step 2335: Determine whether the light intensity value S1, S2, S3, or S4 is lower than the low intensity threshold BL and the duration reaches the second time threshold T_th2. If yes, proceed to step 2337; otherwise, proceed to step 2336.

[0322] Step 2336: Rotate the concave mirror 4 to the parking angle and keep it closed for a time T_rs.

[0323] Step 2337: Rotate the concave mirror 4 to the initial angle.

[0324] An embodiment 9 is provided for the aforementioned operating method, wherein the relevant parameters are set to be the same as those in embodiment 8, and the high-intensity threshold BH is increased to 8000 Lux.

[0325] The scenario in Example 9 is as follows: A vehicle is driving on an open road on a sunny summer noon. Strong sunlight penetrates the windshield from above and flows back into the head-up display. After being reflected and focused by the concave mirror 4 and the reflector 3, the sunlight shines on the lower right corner of the display panel.

[0326] The procedure to handle this situation is as follows: Monitoring begins at time T1. The light intensity value S4 exceeds the high-intensity threshold BH, and the light intensity values ​​S1, S2, and S4 all exceed the medium-intensity threshold BM (4000 Lux) for a duration reaching the first time threshold T_th1. Therefore, at time T2, the concave mirror 4 is rotated downwards by an angle θ. Next, the light intensity values ​​S1 and S2 are both below the low-intensity threshold BL for a duration reaching the second time threshold T_th2. Therefore, at time T3, the concave mirror 4 is rotated back to its initial angle.

[0327] During this process, viewers can see the image on the head-up display, with only a slight difference in image height, and the display panel is protected from damage due to high temperatures caused by sunlight streaming in.

[0328] 2: Display Module 21: Display Panel 22: Backlight element 3: Reflector 31: Reflective polarizer 4: Concave mirror 5: Light sensing module 50: Circuit board 6: Neutral Density Filter 1411~2337: Steps LS, LS1, LS2, LS3, LS4: Light sensors E_m, E_d, E_u: eye position F: Focus G: Windshield h: diameter D: Image Light OL: light outlet VI, VI_d, VI_m, VI_u: virtual image SL: Sunshine S_im: Real image of the sun STA: Beam scattering angle S_bsp: Sunlight spots on the display panel S_bsr: Sunlight spot on the reflector S: S-polarized wave P:P polarized wave BL: Low Intensity Threshold BM: Medium Intensity Threshold BH: High-intensity threshold BDL: Low Difference Threshold BDH: High Differential Threshold TS: Temperature Detector T_th1: First time threshold T_th2: Second time threshold T_rs: Closing time θ: minimum angle

Claims

1. A head-up display (HUD) device for preventing sunlight damage, projecting an image light onto a windshield, the device comprising: a display module having a display panel and a backlight element for generating the image light; a reflector for reflecting the image light from the display module; a concave mirror for reflecting the image light from the reflector onto the windshield, the concave mirror being rotatable upwards or downwards; and a light sensing module disposed on the side of the reflector away from the concave mirror, characterized in that: the light sensing module has a first light sensor and a second light sensor for detecting sunlight entering the HUD device and generating a first light intensity value and a second light intensity value, the area of ​​the sunlight illuminating the reflector being defined as a reflector sunlight spot, and the area of ​​the sunlight illuminating the display panel being defined as a display panel sunlight spot; wherein... The first photosensor is disposed on the upper half of the reflector. When sunlight shines on the outer side of the lower edge of the display panel, the first photosensor is located on the outer side of the upper edge of the sunlight spot on the reflector. The second photosensor is disposed on the lower half of the reflector. When sunlight shines on the outer side of the upper edge of the display panel, the second photosensor is located on the outer side of the lower edge of the sunlight spot on the reflector. When sunlight shines on the display panel and forms the sunlight spot on the display panel, both the first photosensor and the second photosensor are within the sunlight spot on the reflector. When there is no sunlight spot on the display panel, at least one of the first photosensor and the second photosensor is not within the sunlight spot on the reflector.

2. The head-up display device for avoiding sunlight damage as described in claim 1, wherein when both the first light intensity value and the second light intensity value are greater than a medium intensity threshold and the duration reaches a first time threshold, the concave mirror rotates for the first time from an initial angle, the rotation direction being upward or downward.

3. The head-up display device for avoiding sun damage as described in claim 2, wherein the minimum angle of rotation of the concave mirror is 0.265 degrees.

4. The head-up display device for avoiding sunlight damage as described in claim 2, wherein when the first light intensity value exceeds a high intensity threshold and the duration reaches the first time threshold, the concave mirror first rotates in the direction that moves the sunlight spot on the reflector toward the location of the first light sensor; when the second light intensity value exceeds a high intensity threshold and the duration reaches the first time threshold, the concave mirror first rotates in the direction that moves the sunlight spot on the reflector toward the location of the second light sensor.

5. The head-up display device for avoiding sunlight damage as described in claim 2, wherein when the first light intensity value is greater than the second light intensity value, and the difference between the two exceeds a high difference threshold, and the duration reaches the first time threshold, the direction in which the concave mirror first rotates is the direction in which the sunlight spot on the reflector moves toward the location of the first photosensor; when the second light intensity value is greater than the first light intensity value, and the difference between the two exceeds a high difference threshold, and the duration reaches the first time threshold, the direction in which the concave mirror first rotates is the direction in which the sunlight spot on the reflector moves toward the location of the second photosensor.

6. The head-up display device for avoiding sunlight damage as described in claim 1, wherein the light sensing module further includes a third light sensor and a fourth light sensor, generating a third light intensity value and a fourth light intensity value; the third light sensor is disposed on the left half of the reflector, and when sunlight shines on the outer left edge of the display panel, the third light sensor is located on the outer left edge of the sunlight spot on the reflector; the fourth light sensor is disposed on the right half of the reflector, and when sunlight shines on the outer right edge of the display panel, the fourth light sensor is located on the outer right edge of the sunlight spot on the reflector; when there is a sunlight spot on the display panel, all the light sensors are within the sunlight spot on the reflector, and when there is no sunlight spot on the display panel, at least one of the light sensors is not within the sunlight spot on the reflector.

7. The head-up display device for avoiding sunlight damage as described in claim 6, wherein when the light intensity values ​​detected by the light sensors all exceed a medium intensity threshold and the duration reaches a first time threshold, the concave mirror rotates for the first time from an initial angle, the direction of rotation being upward or downward.

8. The head-up display device for avoiding sun damage as described in claim 7, wherein the minimum angle of rotation of the concave mirror is 0.265 degrees.

9. The head-up display device for avoiding sunlight damage as described in claim 8, wherein when the first light intensity value exceeds a high intensity threshold and the duration reaches the first time threshold, the concave mirror rotates upward for the first time; and when the second light intensity value exceeds a high intensity threshold and the duration reaches the first time threshold, the concave mirror rotates downward for the first time.

10. A head-up display device for avoiding sunlight damage as described in claims 2, 4, 5, 7 or 9, wherein after the concave mirror rotates for the first time, if one of the light intensity values ​​is lower than a low intensity threshold and the duration reaches a second time threshold, the concave mirror rotates back to the initial angle; otherwise, the concave mirror rotates a second time in the opposite direction, the second rotation angle being twice the first rotation angle.

11. The head-up display device for avoiding sunlight damage as described in claim 10, wherein after the concave mirror rotates for the second time, if one of the light intensity values ​​is lower than a low intensity threshold and the duration reaches the second time threshold, the concave mirror rotates back to the initial angle; otherwise, the concave mirror is controlled to rotate to a stop angle, maintained for a shutdown time, and then the concave mirror is controlled to rotate back to the initial angle.

12. A head-up display (HUD) device for preventing sunlight damage, projecting an image light onto a windshield, the device comprising: a display module having a display panel and a backlight element for generating the image light; a reflector for reflecting the image light from the display module; a concave mirror for reflecting the image light from the reflector onto the windshield, the concave mirror being rotatable upwards or downwards; and a light sensing module disposed on the side of the reflector away from the concave mirror, characterized in that: the light sensing module has a first light sensor, a second light sensor, a third light sensor, and a fourth light sensor, detecting sunlight entering the HUD device and generating a first light intensity value, a second light intensity value, a third light intensity value, and a fourth light intensity value, the area of ​​the sunlight illuminating the reflector being defined as a reflector sunlight spot, and the area of ​​the sunlight illuminating the display panel being defined as a display panel sunlight spot; wherein... The first light sensor is located on the upper left half of the reflector. When sunlight shines on the outer edge of the lower left corner of the display panel, the first light sensor is located on the outer edge of the upper left corner of the sunlight spot on the reflector. The second light sensor is located on the upper right half of the reflector. When sunlight shines on the outer edge of the lower right corner of the display panel, the second light sensor is located on the outer edge of the upper right corner of the sunlight spot on the reflector. The third light sensor is located on the lower right half of the reflector. When sunlight shines on the outer edge of the upper right corner of the display panel, the third light sensor is located on the outer edge of the lower right corner of the sunlight spot on the reflector. The fourth light sensor is located on the lower left half of the reflector. When sunlight shines on the outer edge of the upper left corner of the display panel, the fourth light sensor is located on the outer edge of the lower left corner of the sunlight spot on the reflector. When sunlight shines on the display panel and forms a sunlight spot, all the light sensors are within the sunlight spot on the reflector. When there is no sunlight spot on the display panel, at least one of the light sensors is not within the sunlight spot on the reflector.

13. The head-up display device for avoiding sunlight damage as described in claim 12, wherein when the light intensity values ​​detected by the light sensors all exceed a medium intensity threshold and the duration reaches a first time threshold, the concave mirror rotates for the first time from an initial angle, the direction of rotation being upward or downward.

14. The head-up display device for avoiding sun damage as described in claim 13, wherein the minimum angle of rotation of the concave mirror is 0.265 degrees.

15. The head-up display device for avoiding sunlight damage as described in claim 12, wherein if the first light intensity value or the second light intensity value exceeds a high intensity threshold and the duration reaches a first time threshold, the concave mirror is rotated for the first time from an initial angle in the direction that moves the sunlight spot on the reflector upward.

16. The head-up display device for avoiding sunlight damage as described in claim 12, wherein if the third light intensity value or the fourth light intensity value exceeds a high intensity threshold and the duration reaches a first time threshold, the concave mirror is rotated for the first time from an initial angle in the direction that moves the sunlight spot on the reflector downward.

17. A head-up display device for avoiding sunlight damage as described in claims 13, 15 or 16, wherein after the concave mirror rotates for the first time, if one of the light intensity values ​​is lower than a low intensity threshold and the duration reaches a second time threshold, the concave mirror rotates back to the initial angle; otherwise, the concave mirror rotates a second time in the opposite direction, the second rotation angle being twice the first rotation angle.

18. The head-up display device for avoiding sunlight damage as described in claim 17, wherein after the concave mirror rotates a second time, if one of the light intensity values ​​is lower than a low intensity threshold and the duration reaches the second time threshold, the concave mirror rotates back to the initial angle; otherwise, the concave mirror is controlled to rotate to a stop angle, held for a shutdown time, and then controlled to rotate back to the initial angle.

19. A head-up display device for avoiding sunlight damage as described in claim 1 or 12, wherein the reflector is a reflective polarizer that allows P-polarized waves to pass through and reflects S-polarized waves.

20. The head-up display device for avoiding sunlight damage as described in claim 19, wherein a light-reducing filter is provided between the reflective polarizer and the light sensing module, the light-reducing filter attenuating 60-90% of the light and having a surface reflectivity of less than 15%.

Images