DE102020125168B3 - Head-up display device and method of operation thereof - Google Patents

Abstract

A head-up display device according to the invention and an operating method thereof comprise a detection board for detecting the radiation intensity of the sunlight and the light focusing positions, wherein the detection board according to the ambient temperature in the head-up display device and the backlight brightness of the backlight component determines whether the Backlight brightness of the backlight component should be reduced or the backlight component should be turned off in order to prevent the display panel from being damaged by thermal focusing caused by sunlight, and also to prevent the backlight brightness of the backlight component being reduced or the backlight component turned off too often .

Description

field of invention

The present invention relates to a display, and more particularly to a vehicle-mounted head-up display device and an operating method thereof.

State of the art

The head-up display technology used in vehicles today is an optical system that usually consists of two main devices, namely a projector and a combining mirror. The projector consists of a signal light source, a projection mirror and other optical elements. The signal light source of the projector consists of an LCD liquid crystal display or a CRT cathode ray tube, the light emitted from the signal light source is then projected by the projector to the combining mirror on a glass panel (or on a special transparent screen), after which the texts or images are displayed indicated by the combining mirror.

A common head-up display for vehicles is from Japanese patent JP 2000347127 A known (cf. 1(A) ). To generate the virtual image displayed by a head-up display (HUD) in front of the windshield A1, a display image is enlarged by the concave mirror A3, which is similar to the enlarging principle of the converging lens. As in 1(B) As shown, the HUD is mounted under the front windshield A1 of the vehicle. When sunlight is incident at a certain angle, the light is focused on the display panel A4 by the concave mirror A3, causing the display panel (such as a liquid crystal panel) to quickly rise in temperature, which may cause it to catch fire. In particular, the AR-HUD requires a minimum virtual image distance (VID) of 10 meters or more, so the magnification of the concave mirror must exceed 20X. The higher the magnification, the closer the display panel is to the focal point of the concave mirror. The closer the focal point, the smaller the solar collection area and the stronger the heat concentration effect. Therefore, solar heat is the most difficult problem to solve for AR HUDs.

It will be on 2 referenced. When sunlight enters the HUD obliquely, after being focused by the second reflector B2, it is reflected by the first reflector B1 and reaches the display panel B3. When the sunlight is focused on the corners of the display panel B3, the focusing effect is maximized because the light path distance is longer and closer to the focal point of the concave mirror.

It will be on 3 Reference is made which shows a conventional solution. Here, the temperature sensor T1 is located near the corner of the display panel where sunlight is easy to focus. Since the HUD backlight element is also an important factor affecting the temperature rise of the display panel, the backlight brightness will be reduced or the backlight will be turned off when the temperature rises so much that the display panel may be damaged. Since the temperature sensor T1 blocks light, whether it is on the front or back of the display panel or on the internal TFT substrate, it will adversely affect the display effect. If the temperature sensor T2 is on the edge of the display panel, e.g. B. on one side of the glass substrate, on the extended TFT substrate, on the driver IC PCB, the problems of delay and generation of errors in detecting the temperature rise occur. In order to ensure that the display panel does not suffer any damage, it is better to classify the result as dangerous than to ignore it. Therefore, the possibility of turning off the backlight component or reducing the backlight brightness of the backlight component greatly increases, which greatly degrades the image display quality of the HUD.

It will be on 4 Reference is made which shows another conventional solution. When in the US patent US9423615B2 The head-up display (HUD) described is one that blocks external light from entering the LCD panel to prevent damage to it. A cold mirror is used for the first reflector C1 or the second reflector C2 to reflect visible light and ensure transmission of infrared light, thus reducing the energy of sunlight entering the LCD panel. An infrared light sensor C3 is mounted behind the dichroic mirror to detect the intensity of infrared light passing through the dichroic mirror. Once the intensity exceeds a predetermined threshold, the backlight brightness is reduced or the backlight is turned off. This introduces an additional problem that reducing the backlight brightness or turning off the backlight is done too often.

The cold light mirror used is a special mirror (cf. 5 ). It does not reflect infrared light, which can reduce more than half of the sun's energy. The area of the first However, the dichroic mirror used is too large and the cost is high. If the dichroic mirror is also used for the second reflector, the area is even larger and it is even more uneconomical.

In order to solve the technical disadvantages described above, various solutions have been proposed in the industry, the technologies in this context being disclosed in the previous patents US9638918B2 , JP 4788882 B2 , CN 103270436B , US9251738B2 , US10102826B2 , US 9612463 B2 , CN 209366054 U , CN 208459693 U , CN 207374131 U , CN 109932824A and CN 109952527A are described.

Supplementary is also on document DE 10 2014 214 976 A1 is pointed out, which relates to a display device, a head-up display system and a method and an apparatus for operating such a display device, wherein a direct spatially resolved temperature measurement of an imager is shown. document DE 10 2018 130 151 A1 shows a conventional mirror unit for a head-up display for detecting the display light, the sunlight being eliminated as an interference signal, and document DE 10 2018 211 700 A1 describes a head-up display device for determining the intensity of sunlight, in which a detection board is arranged in a receiving space and is located remote from a second reflector on the back of a first reflector and is provided with a plurality of light sensor elements which form part of the capture sunlight passing through the first reflector.

The head-up display application technology already described in the above-mentioned previous patents still frequently encounters defects in use.

object of the invention

The object of the invention is to eliminate the above disadvantages and to provide a head-up display device, and in particular a head-up display, which prevents the display panel from being damaged by thermal focusing caused by sunlight .

In order to achieve the above object, the present invention provides a head-up display device, comprising: a main body, wherein an accommodating space and a light outlet are provided inside the main body; a display module arranged in the receiving space and having a display panel and a backlight component, the backlight component having a backlight brightness; a first reflector arranged in the accommodation space; a second reflector disposed in the accommodating space opposite to the first reflector; and a detection board disposed in the accommodating space and located relatively far from the second reflector on the back side of the first reflector and provided with a plurality of light sensing elements; wherein sunlight enters the light outlet and is focused by the second reflector, and then reflected to the first reflector, and then further reflected by the first reflector to the display panel, wherein the detection board according to the signal distribution of the plurality of light sensor elements obtains the light focusing positions of the sunlight projected on the display panel and obtains the irradiance of the sunlight according to the signal strength of the plurality of light sensor elements.

Preferably, the head-up display device further includes a thermal mirror disposed at an arbitrary position in the light path from the display panel to the light outlet.

Preferably, the head-up display device further comprises a polarizer, which is arranged at an arbitrary position in the light path from the display panel to the light outlet.

Preferably, the head-up display device further includes a fan.

Furthermore, a temperature detection module is preferably arranged in the receiving space of the head-up display device.

Preferably the second reflector is a concave mirror or a curved mirror.

Preferably the first reflector is a flat mirror or a curved mirror.

Preferably, the average transmittance of the first reflector in the visible and infrared spectra is less than 15%.

The light sensor elements preferably detect visible light or infrared light or visible light and infrared light.

Another configuration of the present invention provides a head-up display device, comprising: a main body, wherein an accommodating space and a light outlet are provided inside the main body; a display module arranged in the receiving space and has a display panel and a backlight component, the backlight component having a backlight brightness; a first reflector arranged in the accommodation space; a second reflector arranged in the accommodation space; a thermal mirror placed at an arbitrary position in the light path from the display panel to the first reflector, wherein an included angle θ of less than 90° and more than 0° is provided between the mirror surface of the thermal mirror and the light path; and a detection board disposed in the accommodating space and located adjacent to the light path between the first reflector and the heat mirror and provided with a plurality of light sensing elements; whereby sunlight enters the light outlet and is focused by the second reflector and then reflected to the first reflector and then further reflected by the first reflector to the heat mirror, with part of the sunlight passing through the heat mirror and then reaching the display panel and the other part of the sunlight is reflected by the heat mirror and then reaches the detection board, the detection board obtaining the light focusing positions of the sunlight projected on the display panel according to the signal distribution of the plurality of light sensor elements, and obtaining the radiation intensity of the sunlight according to the signal strength of the plurality of light sensor elements.

Preferably, the head-up display device further comprises a polarizer, which is arranged at an arbitrary position in the light path from the display panel to the light outlet.

Preferably, the head-up display device further includes a fan.

Furthermore, a temperature detection module is preferably arranged in the receiving space of the head-up display device.

Preferably the second reflector is a concave mirror or a curved mirror.

Preferably the first reflector is a flat mirror or a curved mirror.

The light sensor elements preferably detect visible light or infrared light or visible light and infrared light.

Further, the temperature detection module detects the ambient temperature in the head-up display device, and compares the conditions of the light focusing position, the irradiance, the ambient temperature and the backlight brightness with the software simulated results or actual experimental results to show the possible temperature on the display panel for the light focusing points - estimate time curves; wherein the backlight brightness is reduced or the backlight is turned off before the light focusing points on the display panel reach the heat-resistance limit temperature, to prevent the display panel from being damaged by thermal focusing caused by sunlight, and further to prevent reducing the backlight brightness or the Turning off the backlight is made too often.

Furthermore, the present invention provides an operating method for the head-up display device, wherein at least one backlight component, a display panel, a first reflector, a second reflector and a windshield sequentially in the light path of the virtual image display of the head-up display device are arranged. The steps of the operating method include the following: detecting the sunlight reaching and passing through the first reflector by means of the plurality of light sensor elements of the detection board, or detecting a part of the sunlight reflected by the heat mirror arranged between the first reflector and the display panel to determine a light focusing position and the radiation intensity to obtain the sunlight projected on the display panel; calculating the time required for a light focusing point on the display panel to reach the heat resistance limit temperature according to the light focusing position, the irradiance, the backlight brightness of the backlight component, and the ambient temperature in the head-up display device; and reducing the backlight brightness of the backlight component and turning off the backlight component, or first reducing the backlight brightness of the backlight component and then turning off the backlight component before the time is reached.

Here, the time required for the panel to reach the heat-resistance limit temperature is calculated using a temperature estimation formula, and the parameters used in the temperature estimation formula include irradiance, light focusing position, ambient temperature, and backlight brightness.

In this case, a plurality of irradiation positions are defined for the plurality of light sensor elements, with the light focusing positions being derived from a read signal value of the plurality of irradiation positions can be obtained by selecting the values above a threshold or the highest values.

Ordinary reflectors are used in the present invention. By using a small part of the light passing through the reflectors, including the visible light and infrared light, or by using a part of the light reflected by the heat mirror, the sunlight is captured to effectively reduce costs. Without using the temperature sensor placed on the display panel, the projected light is not blocked and the picture quality is not affected. In addition, the present invention has a high estimation accuracy and only reduces the backlight brightness or turns off the backlight only when necessary.

character list

• 1 Fig. 12 shows a schematic representation of a conventional head-up display;
• 2 Fig. 12 shows a schematic representation of the solar projection of the conventional head-up display;
• 3 Fig. 12 shows a schematic representation of a conventional liquid crystal display panel and a temperature sensor;
• 4 Fig. 12 is a schematic diagram of a conventional head-up display in which solar heat countermeasures have been taken;
• 5 shows a schematic representation of a conventional dichroic mirror;
• 6 shows a schematic representation of a first embodiment according to the present invention;
• 7 shows a schematic representation of sunlight focusing;
• 8th shows another schematic representation of sunlight focusing;
• 9 shows a schematic representation of a second embodiment according to the present invention;
• 10 shows a schematic representation of a third embodiment according to the present invention;
• 11 shows a schematic representation of a fourth embodiment according to the present invention;
• 12 shows a schematic representation of a fifth embodiment according to the present invention;
• 13 Fig. 12 shows a schematic simulation diagram of the temperature-time curves of the light focusing points on the display panel when the sunlight is focused;
• 14 Fig. 12 shows diagrams for determining the distribution of signals of focusing sunlight in the first to fifth embodiments;
• 15 and 16 show schematic representations of a sixth embodiment according to the present invention;
• 17 shows a schematic representation of a seventh embodiment according to the present invention;
• 18 shows a schematic representation of an eighth embodiment according to the present invention;
• 19 shows a schematic representation of a ninth embodiment according to the present invention;
• 20 Fig. 12 shows schematic representations for determining the distribution of signals of the sunlight focussing in the sixth to ninth embodiments.

Detailed description of the exemplary embodiments

For a complete understanding of the specific implementation, the structure and the achieved effects of the present invention, the exemplary embodiments are described in detail below with reference to the figures.

It will be on the 6 until 12 Reference are made which show a head-up display device. The head-up display device comprises: a main body 1, wherein an accommodating space 11 and a light outlet 12 are provided inside the main body, and the main body 1 is placed under a windshield G and embedded in the vehicle instrument panel; a display module 2 which is arranged in the accommodating space 11 and is for projecting an image light and has a display panel 21 and a backlight component 22; a first reflector 3 which is arranged in the accommodation space 11 and is a flat mirror or a curved mirror; a second reflector 4 which is arranged in the receiving space 11 opposite to the first reflector 3 and is a concave mirror or a curved mirror; and a detection board 5 which is arranged in the accommodating space 11 and is located relatively far from the second reflector 4 on the rear side of the first reflector 3 and is provided with a plurality of light sensor elements 51 .

In the present exemplary embodiment, the first reflector 3 is a reflector 3 with low light transmission. Sunlight S coming from the outside of the vehicle enters the light outlet 12 through the windshield G and is focused by the second reflector 4 and then reflected to the first reflector 3 and then further reflected by the first reflector 3 to the display panel 21 . Here, the light transmittance of the first reflector 3 is low (the light transmittance is lower than 15% and the reflectance is higher than 85%). Most of the light (e.g. about 94%) is reflected to the display panel 21, but a small proportion (e.g. about 0.05%) passes through the first reflector 3 and reaches the detection board 5. The light sensor elements 51 arranged behind the first reflector 3 can detect visible light or infrared light or visible light and infrared light. According to the signal distribution of the multiple light sensor elements 51, the detection board can obtain the light focusing positions of the sunlight S projected on the display panel 21, and according to the signal strength of the multiple light sensor elements 51, obtain the irradiance of the sunlight S to determine whether the irradiance of the sunlight is strong enough that damaging display panel 21.

Both the sunlight S and the image light projected by the display module 2 are irradiated on the first reflector 3, but the brightness of the sunlight S, the intensity of which is strong enough to damage the display panel 21, is higher than that of the projected image light. After entering the head-up display device, the sunlight is focused by the second reflector 4 before reaching the first reflector 3 . The brightness at this time is much higher than the original brightness of the sunlight S. Therefore, whether strong sunlight S is currently radiating and whether it is strong enough to damage the display panel 21 can be clearly determined from the signal strength of the plurality of light sensor elements 51 . For example, when there is only the image light projected on the display panel 21, the read signal values of the plurality of light sensor elements 51 are 0.2 at most. When the sunlight strong enough to damage the display panel 21 is focused, the read signal values of the plurality of light sensor elements 51 are greater than 2 at most. The difference between the two read signal values is more than ten times. Therefore, the system can clearly determine whether the signal is made by the sunlight S irradiation.

It will be on the 7 and 8th Reference is made which shows schematic representations of the focusing of the sunlight S. When the temperature reaches the highest value, the total heat of the sunlight S incident on the head-up display device may not be the highest. When the sunlight S is oblique and the focused light falls on a corner of the display panel 21, the thermal focusing effect is best, so that the hottest conditions occur when a light focusing point on the display panel 21 is particularly hot. When the phenomenon of thermal focusing of the sunlight S occurs, it is determined according to the radiation intensity and the light focusing position, for example, when the radiation intensity is greater than the predetermined threshold and the light focusing position falls within a certain range, whether the backlight brightness of the backlight component 22 should be reduced and how much the backlight brightness of the backlight component 22 should be reduced or whether the backlight component 22 should be turned off to avoid overheating in a light focusing point on the display panel 21 .

It will be on 9 Reference is made to which shows a schematic representation of a second embodiment according to the present invention. The head-up display device further comprises a heat mirror 6 (hot mirror) which is arranged in the accommodation space 11 and is located on one side of the display module 2 . In the energy spectrum of sunlight S falling on the ground, about 46% of the energy is in visible light and ultraviolet light (about 1%) with a wavelength below 700 nm, and further about 54% of the energy is in infrared light with a wavelength longer than 700 nm. A thermal mirror 6 that reflects infrared light and transmits visible light is mounted on the front of the display panel 21 to allow the infrared light in the sunlight S to exit the projected light path and filter more than half of the sunlight heat. Here, the heat mirror 6, with which the effect of lowering the temperature can be obtained, has a small area and is inexpensive. In other exemplary embodiments, the thermal mirror 6 can be arranged at any position in the light path from the display panel 21 to the light outlet 12 .

It will be on 10 Reference is made to which shows a schematic representation of a third embodiment according to the present invention. Here, the head-up display device further comprises a polarizer 7, which is arranged between the heating mirror 6 and the display panel 21, and filters the P-polarized sunlight passing through the windshield G to achieve the temperature lowering effect. In other embodiments, the polarizer 7 at a any position in the light path from the display panel 21 to the light outlet 12 can be arranged.

It will be on 11 Reference is made to which shows a schematic representation of a fourth embodiment according to the present invention. Here, the head-up display device further includes a fan 8 disposed on a side of the display panel 21, the fan 8 assisting the display panel 21 in heat dissipation to achieve the temperature lowering effect.

It will be on 12 Reference is made to which shows a schematic representation of a fifth embodiment according to the present invention. Here, the head-up display device further includes a temperature detection module 9 arranged in the accommodation space, the temperature detection module 9 detecting the ambient temperature in the head-up display device and supporting the evaluation of the estimation of the temperature of the display panel 21 .

It will be on 13 Referring now to FIG. 1, which shows a schematic simulation diagram of the temperature-time curves of the light focusing points on the display panel 21 when the sunlight is focused. The temperature-time curves of the light focusing points on the display panel 21 can be simulated by optical simulation software. Further, the temperature-time curve of a light-focusing point under conditions of different radiation intensities, different light-focusing positions, different ambient temperatures, and different backlight brightnesses can be obtained through experimental measurements. This data is stored in the head-up display device for later estimation of the temperature at the light focus points. For example, if the heat resistance limit temperature of the display panel is 21105 degrees (°C), the ambient temperature in the head-up display device is 70 degrees (°C), the backlight brightness of the backlight component 22 is 100%, the sunlight coming from outside the vehicle with an illuminance of 1400 W/m ² is focused on the central area of the display panel 21 and the read signal value of the light sensor elements is 2.0, it can be seen from the figure that if no countermeasures are taken, the light focusing points on the display panel 21 after reach 130 degrees (°C) for four minutes, which exceeds the heat resistance limit temperature of the display panel 21 . In the present invention, the backlight brightness of the backlight component 22 can be reduced by 50% after the condition has lasted for one minute, and the backlight can be turned off after the condition has lasted for two minutes. In this way, the temperature of the light focusing points can be prevented from exceeding the upper limit of 105 degrees (°C).

the end 13 it can be seen that when the ambient temperature in the head-up display device is 40 degrees (°C), the light focus points on the display panel 21 reach 95 degrees (°C) after four minutes, and this temperature is still below the heat resistance limit of the Display panel 21 is located. Therefore, the backlight brightness of the backlight component 22 is not reduced within four minutes after the in-focus state resumes, and the backlight brightness of the backlight component 22 is only decreased by 25% after the four minutes after the in-focus state resumes, in order to provide users with a view to the display quality of the head- up displays to minimize the disruptions. When the vehicle is running, the vehicle is steered and moves relative to the sun, and thereby the light focusing position may not remain in the same position for a long time. In the present invention, the irradiance of the sunlight S, the light focusing position, the ambient temperature in the head-up display device, and the backlight brightness of the backlight component are detected. These conditions are compared to the software simulated results or actual experimental results to obtain the results corresponding to the closest numerical curve. With the possible temperature-time curve for estimating the light focusing points on the display panel 21, the backlight brightness of the backlight component can be reduced or the backlight component can be switched off at the estimated point in time. The display panel 21 can be prevented from being damaged by thermal focusing caused by sunlight S. It can also be prevented that reducing the backlight brightness of the backlight component or turning off the backlight component is done too often, which would otherwise result in deterioration of the display quality.

Furthermore, the present invention provides an operating method for the head-up display device, in which a part of the sunlight S passing through the first reflector 3 is detected by the plurality of light sensor elements 51 of the detection board 5 to determine the light focusing position L and the radiation intensity IS of the on a display panel 21 projected sunlight S and through the Tem to determine temperature detection module 9 detected ambient temperature ET in the head-up display device and also to set the backlight brightness B of the backlight component 22. According to the light focusing position L, the irradiance IS, the ambient temperature ET and the backlight brightness B, it can be calculated how long it takes for the light focusing points of the sunlight shining on the display panel 21 to reach the heat resistance limit temperature under these conditions, and it can be evaluated when the brightness of the backlight component 22 has to be reduced or the backlight component 22 has to be turned off in order to prevent the display panel 21 from being damaged by thermal focusing caused by sunlight S, and also to prevent reducing the backlight brightness of the backlight component or turning off the backlight component from increasing is done often, which would otherwise degrade the display quality.

The positions where the sunlight S passes through the first reflector 3 and then reaches the detection board 5 and the light focusing positions of the sunlight S projected on the display panel 21 are in 14A shown. The light focus position L to be calculated is calculated by first defining a plurality of light focus positions on the display panel 21 (cf. 14C ) and then, according to the signal strength and distribution of the plurality of light sensor elements 51 receiving the sunlight S, the distribution center of the detection board 5 on which the sunlight S falls is obtained (cf. 14B) , to the in 14C corresponding light focusing position L shown on the display panel 21 via the distribution center. The value of a light focusing position L is inversely proportional to the area of a light focusing point. The more focused the light, the smaller the area of a light focusing point and the larger the value of the corresponding light focusing position L; The less focused the light, the larger the area of a light focusing point and the smaller the value of the corresponding light focusing position L. For example, the display panel 21 can be divided into a twenty-five grid, namely twenty-five light focusing positions. The central area has a value of 0.1 and the edge area has a value of 1.6. The area from the center to the edge increases in a geometric order (cf. 14C ). In addition, the display panel can also be divided into other grid numbers and increased in other orders. The center of distribution of the sunlight S projected on the detection board 5 can be determined, for example, in the read signal values of the plurality of light sensor elements 51 by the distribution of the positions of the light sensor elements (such as the position BA in 14B) , whose values are higher than those of the upper quartile, are determined, then the corresponding value of the light focus position L on the display panel, such as the value 0.8 in 14C , searched, or the position of the light sensor element having the highest value is regarded as the center of distribution, and then the corresponding value of the light focusing position L is searched from this position.

The radiation intensity IS to be calculated is determined according to the signal strength of the sunlight S received by the light sensor elements 51 . For example, the read signal value of each light sensor element 51 can be calculated by averaging or by RMS calculation of the read signal values of the multiple light sensor elements (possibly in the range of 0.1 to 3.0), e.g. of values higher than those of the upper quartile, or by averaging or by RMS calculation of the highest signal values read, to obtain the value representing the actual irradiance IS of the sunlight.

The ambient temperature ET to be calculated is the current ambient temperature in the head-up display device, which is obtained by the temperature detection module 9 and is specified in the unit Celsius.

The backlight brightness B of the backlight component 21 to be calculated ranges from 0% to 100%, and the corresponding values are 0 to 1.0, for example.

It will be on the 15 and 16 Reference is made to show schematic representations of a sixth embodiment according to the present invention. The head-up display device comprises: a main body 1, wherein an accommodating space 11 and a light outlet 12 are provided inside the main body, and the main body 1 is placed under a windshield G and embedded in the vehicle instrument panel; a display module 2 which is arranged in the accommodating space 11 and is for projecting an image light and has a display panel 21 and a backlight component 22; a first reflector 3 which is arranged in the accommodation space 11 and is a flat mirror or a curved mirror; a second reflector 4 which is arranged in the receiving space 11 and is a concave mirror or a curved mirror; a thermal mirror 6 placed at an arbitrary position in the light path from the display module 2 to the first reflector 3, including a an angle θ of less than 90° and more than 0° is provided between the mirror surface 61 of the heat mirror 6 and the light path; and a detection board 5 which is arranged in the accommodating space 11 and is located beside the light path between the first reflector 3 and the heat mirror 6 and is provided with a plurality of light sensor elements 51 .

In the sixth embodiment, a sunlight S coming from the outside of the vehicle enters the light outlet 12 through the windshield G and is focused by the second reflector 4 and then reflected to the first reflector 3 and is then further reflected by the first reflector 3 to the heat mirror 6 . Part of the sunlight passes through the thermal mirror 6 and then reaches the display panel 21. The other part of the sunlight is reflected by the thermal mirror and then reaches the detection board 5 Thermal mirror 6 to the detection board 5 reflects and most of the visible light (for example, more than 85% of the visible light) passes through the thermal mirror and reaches the detection board 5. The light sensor elements 51 arranged on the detection board 5 can be visible light or infrared light or visible light and detect infrared light. According to the signal distribution of the multiple light sensor elements 51, the detection board can obtain the light focusing positions of the sunlight S projected on the display panel 21, and according to the signal strength of the multiple light sensor elements 51, obtain the irradiance of the sunlight S to determine whether the irradiance of the sunlight is strong enough that damaging display panel 21.

It will be on 17 Reference is made, which shows a schematic representation of a seventh embodiment according to the present invention. Here, the head-up display device further comprises a polarizer 7, which is arranged between the heating mirror 6 and the display panel 21, and filters the P-polarized sunlight passing through the windshield G to achieve the temperature lowering effect. In other exemplary embodiments, the polarizer 7 can be arranged at any position in the light path from the display panel 21 to the light outlet 12 .

It will be on 18 Reference is made, which shows a schematic representation of an eighth embodiment according to the present invention. Here, the head-up display device further includes a fan 8 disposed on a side of the display panel 21, the fan 8 assisting the display panel 21 in heat dissipation to achieve the temperature lowering effect.

It will be on 19 Reference is made, which shows a schematic representation of a ninth embodiment according to the present invention. Here, the head-up display device further includes a temperature detection module 9 arranged in the accommodation space, the temperature detection module 9 detecting the ambient temperature in the head-up display device and supporting the evaluation of the estimation of the temperature of the display panel 21 .

Furthermore, the present invention provides another operating method for the head-up display device, in which a part of the sunlight S reflected by the heat mirror 6 located between the first reflector 3 and the display panel 21 passes through the plurality of light sensor elements 51 of the detection board 5 to determine the light focusing position L and the radiation intensity IS of the sunlight S projected onto the display panel 21 and an ambient temperature ET detected by the temperature detection module 9 in the head-up display device, and further the backlight brightness B of the backlight component 22 to obtain. According to the light focusing position L, the irradiance IS, the ambient temperature ET and the backlight brightness B, it can be calculated how long it takes for the light focusing points of the sunlight shining on the display panel 21 to reach the heat resistance limit temperature under these conditions, and it can be evaluated when the brightness of the backlight component 22 has to be reduced or the backlight component 22 has to be turned off in order to prevent the display panel 21 from being damaged by thermal focusing caused by sunlight S, and also to prevent reducing the backlight brightness of the backlight component or turning off the backlight component from increasing is done often, which would otherwise degrade the display quality.

The position where the sunlight S is reflected by the heat mirror 6 to the detection board 5 and the light focusing position of the sunlight S located on the display panel 21 is in 20A shown. The light focus position L to be calculated is calculated by first defining a plurality of light focus positions on the display panel 21 (cf. 20c ) and then, according to the signal strength and distribution of the plurality of light sensor elements 51 receiving the sunlight S, the distribution center of the detection board 5 on which the sunlight S falls is obtained (cf. 20B) , to the in 20c corresponding light focusing position L shown on the display panel 21 can be found via the distribution center. The value of a light focusing position L is inversely proportional to the area of a light focusing point. The more focused the light, the smaller the area of a light focusing point and the larger the value of the corresponding light focusing position L; The less focused the light, the larger the area of a light focusing point and the smaller the value of the corresponding light focusing position L. For example, the display panel 21 can be divided into a twenty-five grid, namely twenty-five light focusing positions. The central area has a value of 0.1 and the edge area has a value of 1.6. The area from the center to the edge increases in a geometric order (cf. 20c ). In addition, the display panel can also be divided into other grid numbers and increased in other orders. The center of distribution of the sunlight S projected on the detection board 5 can be determined, for example, in the read signal values of the plurality of light sensor elements 51 by the distribution of the positions of the light sensor elements (such as the position BA in 14B) , whose values are higher than those of the upper quartile, are determined, then the corresponding value of the light focus position L on the display panel, such as the value 0.8 in 14C , searched, or the position of the light sensor element having the highest value is regarded as the center of distribution, and then the corresponding value of the light focusing position L is searched from this position.

The radiation intensity IS to be calculated is determined according to the signal strength of the sunlight S received by the light sensor elements 51 . For example, the read signal value of each light sensor element 51 can be calculated by averaging or by RMS calculation of the read signal values of the multiple light sensor elements (possibly in the range of 0.1 to 3.0), e.g. of values higher than those of the upper quartile, or by averaging or by RMS calculation of the highest signal values read, to obtain the value representing the actual irradiance IS of the sunlight.

The ambient temperature ET to be calculated is the current ambient temperature in the head-up display device, which is obtained by the temperature detection module 9 and is specified in the unit Celsius.

The backlight brightness B of the backlight component 21 to be calculated ranges from 0% to 100%, and the corresponding values are 0 to 1.0, for example.

In the present invention, it is calculated when the temperature at a light focusing point on the display panel 21 exceeds the specified heat resistance limit temperature after the elapse of the irradiation time T under the conditions of the light focusing position L, the radiation intensity IS, the ambient temperature ET and the backlight brightness B. Before the estimated temperature at a light focusing point on the display panel 21 exceeds the heat-resistance limit temperature, the backlight brightness of the backlight component 22 is reduced or the backlight component 22 is turned off to prevent the display panel 21 from being damaged when the temperature exceeds the heat-resistance limit temperature. In this way, it can also be prevented that the reduction of the backlight brightness of the backlight component or the switching off of the backlight component is only limited to the radiation intensity of the sunlight S and is carried out too often, which would otherwise lead to a deterioration in the display quality.

Here, the formula for estimating the temperature at a light focusing point on the display panel 21 is given below: $$\left(\text{ET}+273\right)\times k_1{e}^{k_{2}B}-273+\text{IS}\times \text{L}\times k_3{e}^{k_4\frac{ET-25}{ET+273}}\times \text{T}+\text{C}=\text{TP}$$

The heat resistance limit temperature TP of the display panel 21 can be obtained from the display panel specifications. k ₁ and k ₂ are the temperature coefficients of the display panel; k ₃ and k ₄ are the increased temperature coefficients of the display panel; C is the temperature compensation coefficient. These coefficients can be obtained by simulation using software or experimental data. By using this formula for estimating the temperature, it can be estimated when, after the elapse of the irradiation time T under these conditions, the temperature at a light-focusing point on the display panel 21 exceeds the specified heat-resistance limit temperature.

in der Formel zum Schätzen der Temperatur: Die Temperatur des Anzeigefelds 21 steigt aufgrund der Erwärmung der Hintergrundbeleuchtungskomponente 22. Durch unterschiedliche Hintergrundbeleuchtungshelligkeiten B entstehen unterschiedliche Erwärmungseffekte. Aus dem Beispiel der Lichteffizienz der LEDs ist ersichtlich, dass je höher die Helligkeit ist, desto schlechter die Lichteffizienz ist, desto mehr Wärme an das Anzeigefeld geleitet wird, desto mehr Strahlungswärme vom Anzeigefeld absorbiert wird und desto höher die Temperatur des Anzeigefelds ist; Je niedriger die Helligkeit ist, desto besser ist die Lichteffizienz, desto weniger Wärme wird an das Anzeigefeld geleitet, desto weniger Strahlungswärme wird vom Anzeigefeld absorbiert, desto niedriger ist die Temperatur des Anzeigefelds und desto näher ist es an der Umgebungstemperatur ET. Daraus kann geschlossen werden, dass die Beziehung zwischen der Temperatur des Anzeigefelds 21 und der Hintergrundbeleuchtungshelligkeit B durch eine Exponentialfunktion beschreibbar ist. Wenn das Anzeigefeld 21 durch die Hintergrundbeleuchtungskomponente 22 erwärmt wird, hängt der Grad des Temperaturanstiegs auch mit der aktuellen Umgebungstemperatur ET zusammen. Nach dem Newtonschen Gesetz der Kühlung ist die Wärmeableitungsgeschwindigkeit umso schneller, je größer der Temperaturunterschied ist. Wenn daher die Umgebungstemperatur ET niedriger ist, ist die Wärmeableitungsgeschwindigkeit des Anzeigefelds 21 schneller und ist die Temperatur des Anzeigefelds 21 aufgrund der Erwärmung der Hintergrundbeleuchtungskomponente 22 ebenfalls niedriger; Wenn die Umgebungstemperatur ET höher ist, ist die Wärmeableitungsgeschwindigkeit des Anzeigefelds 21 langsamer und ist die Temperatur des Anzeigefelds 21 aufgrund der Erwärmung der Hintergrundbeleuchtungskomponente 22 höher. Daraus kann geschlossen werden, dass die Beziehung zwischen der Temperatur des Anzeigefelds 21 und der Umgebungstemperatur ET gleichfalls durch eine Exponentialfunktion beschreibbar ist. Hierbei ist die Umgebungstemperatur ET der niedrigste Grenzwert der Temperatur des Anzeigefelds 21 und wird die absolute Temperatur zur Umrechnung verwendet. Wenn diese beiden Faktoren kombiniert werden, kann abgeleitet werden, dass die Temperatur des Anzeigefelds $\left(\text{ET}+273\right)\times k_1{e}^{k_{2}B}-273$

beträgt, wenn die Umgebungstemperatur bei ET und die Hintergrundbeleuchtungshelligkeit bei B gehalten werden und keine Sonnenlichteinstrahlung gegeben ist.Explanation of $\left(\text{ET}+273\right)\times k_1{e}^{k_{2}B}-273$

in the formula for estimating the temperature: The temperature of the display panel 21 rises due to the heating of the backlight component 22. Different backlight brightness B gives rise to different heating effects. From the example of the light efficiency of LEDs, it can be seen that the higher the brightness, the worse the light efficiency, the more heat is conducted to the display panel, the more radiant heat the display panel absorbs becomes and the higher the temperature of the display panel; The lower the brightness, the better the light efficiency, the less heat is conducted to the display panel, the less radiant heat is absorbed by the display panel, the lower the temperature of the display panel, and the closer it is to the ambient temperature ET. From this it can be concluded that the relationship between the temperature of the display panel 21 and the backlight brightness B can be described by an exponential function. When the display panel 21 is heated by the backlight component 22, the degree of temperature rise is also related to the current ambient temperature ET. According to Newton's law of cooling, the greater the temperature difference, the faster the heat dissipation speed. Therefore, when the ambient temperature ET is lower, the heat dissipation speed of the display panel 21 is faster, and the temperature of the display panel 21 is also lower due to the heating of the backlight component 22; When the ambient temperature ET is higher, the heat dissipation speed of the display panel 21 is slower and the temperature of the display panel 21 is higher due to heating of the backlight component 22 . From this it can be concluded that the relationship between the temperature of the display panel 21 and the ambient temperature ET can also be described by an exponential function. Here, the ambient temperature ET is the lowest limit of the temperature of the display panel 21, and the absolute temperature is used for the conversion. When these two factors are combined, it can be deduced that the temperature of the display panel $\left(\text{ET}+273\right)\times k_1{e}^{k_{2}B}-273$

when the ambient temperature is kept at ET and the backlight brightness at B with no sunlight exposure.

“ in der Formel zum Schätzen der Temperatur: Je höher die Strahlungsintensität IS des Sonnenlichts ist, desto größer ist der Temperaturanstieg in einem Lichtfokussierpunkt; Je niedriger die Strahlungsintensität IS des Sonnenlichts ist, desto geringer ist der Temperaturanstieg in einem Lichtfokussierpunkt. Daher ist die Strahlungsintensität IS proportional zur Anstiegstemperatur in einem Lichtfokussierpunkt, was einer linearen Funktion entspricht. Das Sonnenlicht wird auf dem Anzeigefeld 21 auf verschiedene Positionen fokussiert und die Flächen der Lichtfokussierpunkte sind unterschiedlich. Wenn die Fläche eines Lichtfokussierpunkts kleiner ist, wird die Sonnenwärme stärker fokussiert und ist der Temperaturanstieg in einem Lichtfokussierpunkt größer; Wenn die Fläche eines Lichtfokussierpunkts größer ist, wird die Sonnenwärme weniger fokussiert und ist der Temperaturanstieg in einem Lichtfokussierpunkt geringer. Daher ist die Fläche eines Lichtfokussierpunkts umgekehrt proportional zur Anstiegstemperatur in einem Lichtfokussierpunkt und ist die Fläche eines Lichtfokussierpunkts umgekehrt proportional zum Wert einer Lichtfokussierposition L, d. h. der Wert einer Lichtfokussierposition L ist proportional zur Anstiegstemperatur in einem Lichtfokussierpunkt, was gleichfalls einer linearen Funktion entspricht. Je länger die Einstrahlzeit T des Sonnenlichts ist, desto größer ist der Temperaturanstieg in einem Lichtfokussierpunkt; Je kürzer die Einstrahlzeit T des Sonnenlichts ist, desto geringer ist der Temperaturanstieg in einem Lichtfokussierpunkt. Daher ist die Einstrahlzeit T proportional zur Anstiegstemperatur in einem Lichtfokussierpunkt, was gleichfalls einer linearen Funktion entspricht. Wenn sich das Anzeigefeld 21 durch Sonnenlicht erwärmt, hängt der Grad des Temperaturanstiegs in einem Lichtfokussierpunkt auch mit der Umgebungstemperatur zu diesem Zeitpunkt zusammen. Nach dem Newtonschen Gesetz der Kühlung ist die Wärmeableitungsgeschwindigkeit umso schneller, je größer der Temperaturunterschied ist. Wenn daher die Umgebungstemperatur ET niedriger ist, ist die Wärmeableitungsgeschwindigkeit des Anzeigefelds 21 schneller und der Temperaturanstieg in einem Lichtfokussierpunkt aufgrund der Erwärmung durch das Sonnenlicht geringer. Wenn die Umgebungstemperatur ET höher ist, ist die Wärmeableitungsgeschwindigkeit des Anzeigefelds 21 langsamer und der Temperaturanstieg in einem Lichtfokussierpunkt aufgrund der Erwärmung durch das Sonnenlicht größer. Daraus kann geschlossen werden, dass die Beziehung zwischen der Anstiegstemperatur in einem Lichtfokussierpunkt auf dem Anzeigefeld 21 und der Umgebungstemperatur ET durch eine Exponentialfunktion beschreibbar ist. Hierbei wird für das Anzeigefeld eine Betriebstemperatur von 25 Grad (°C) als Referenzwert verwendet und die absolute Temperatur zur Umrechnung genutzt. Wenn diese vier Faktoren kombiniert werden, kann abgeleitet werden, dass nach der Einstrahlzeit T, wenn die Umgebungstemperatur bei ET gehalten wird, die Strahlungsintensität des Sonnenlichts IS ist und die Lichtfokussierposition L ist, die Anstiegstemperatur in einem Lichtfokussierpunkt auf dem Anzeigefeld „ $$\text{IS}\times \text{L}\times k_3{e}^{k_4\frac{ET-25}{ET+273}}\times \text{T}$$

‟ beträgt.Explanation of " $\text{IS}\times \text{L}\times k_3{e}^{k_4\frac{ET-25}{ET+273}}\times \text{T}$

” in the formula for estimating temperature: the higher the irradiance IS of sunlight, the greater the temperature rise at a light-focusing point; The lower the irradiance IS of sunlight, the lower the temperature rise at a light focusing point. Therefore, the irradiance IS is proportional to the rising temperature at a light focus point, which corresponds to a linear function. The sunlight is focused on different positions on the display panel 21, and the areas of the light focusing points are different. When the area of a light-focusing point is smaller, solar heat is more focused and the temperature rise in a light-focusing point is larger; When the area of a light focusing point is larger, solar heat is less focused and the temperature rise in a light focusing point is smaller. Therefore, the area of a light-focusing point is inversely proportional to the rise temperature in a light-focusing point, and the area of a light-focusing point is inversely proportional to the value of a light-focusing position L, that is, the value of a light-focusing position L is proportional to the rise temperature in a light-focusing point, which also corresponds to a linear function. The longer the irradiation time T of sunlight, the greater the temperature rise at a light focusing point; The shorter the irradiation time T of sunlight, the smaller the temperature rise at a light focusing point. Therefore, the irradiation time T is proportional to the rising temperature at a light focusing point, which is also a linear function. When the display panel 21 is heated by sunlight, the degree of temperature rise at a light focusing point is also related to the ambient temperature at that time. According to Newton's law of cooling, the greater the temperature difference, the faster the heat dissipation speed. Therefore, when the ambient temperature ET is lower, the heat dissipation speed of the display panel 21 is faster and the temperature rise at a light focusing point due to heating by sunlight is smaller. When the ambient temperature ET is higher, the heat dissipation speed of the display panel 21 is slower and the temperature rise at a light focusing point due to heating by sunlight is larger. From this, it can be concluded that the relationship between the rising temperature at a light-focusing point on the display panel 21 and the ambient temperature ET can be described by an exponential function. An operating temperature of 25 degrees (°C) is used as a reference value for the display panel and the absolute temperature is used for the conversion. When these four factors are combined, it can be deduced that after the irradiation time T, when the ambient temperature is kept at ET, the irradiance of the sunlight is IS and the light focusing position is L, the rise temperature in a light focusing point on the display panel " $$\text{IS}\times \text{L}\times k_3{e}^{k_4\frac{ET-25}{ET+273}}\times \text{T}$$

" amounts to.

Compared to the prior art, the present invention has the following advantages: Ordinary reflectors are used in the present invention. By using a small fraction of the light passing through the reflectors, including visible light and infrared light, or by using part of the light reflected by the heat mirror, sunlight is captured to effectively reduce costs. Without using the temperature sensor placed on the display panel, the projected light is not blocked and the picture quality is not affected. In addition, the present invention does not have the problem of the temperature detection delay in relation to the display panel, thereby improving the estimation accuracy and reducing the occurrence of unnecessary misjudgment, so that the backlight brightness is reduced only when necessary, or the backlight is turned off only when necessary .

Reference List

A1

Windschutzscheibe

A3

Konkavspiegel

A4

Anzeigefeld

B1

erster Reflektor

B2

zweiter Reflektor

B3

Anzeigefeld

C1

erster Reflektor

C2

zweiter Reflektor

C3

Infrarotlichtsensor

T1, T2

Temperatursensor

[vorliegende Erfindung]

S

Sonnenlicht

G

Windschutzscheibe

θ

eingeschlossener Winkel

1

Hauptkörper

11

Aufnahmeraum

12

Lichtauslass

2

Anzeigemodul

21

Anzeigefeld

22

Hintergrundbeleuchtungskomponente

3

erster Reflektor

4

zweiter Reflektor

5

Erfassungsplatine

51

Lichtsensorelement

6

Wärmespiegel

61

Spiegelfläche

7

Polarisator

8

Lüfter

9

Temperaturerfassungsmodul

[State of the art]

A1

windshield

A3

concave mirror

A4

display panel

B1

first reflector

B2

second reflector

B3

display panel

C1

first reflector

C2

second reflector

C3

infrared light sensor

T1, T2

temperature sensor

[present invention]

S

sunlight

G

windshield

θ

included angle

1

main body

11

recording room

12

light outlet

2

display module

21

display panel

22

backlight component

3

first reflector

4

second reflector

5

acquisition board

51

light sensing element

6

heat mirror

61

mirror surface

7

polarizer

8th

Fan

9

temperature acquisition module

Claims (20)

A head-up display device comprising a main body (1), wherein an accommodating space (11) and a light outlet (12) are provided inside the main body (1); a display module (2) which is arranged in the receiving space (11) and has a display panel (21) and a backlight component (22); a first reflector (3) which is arranged in the receiving space (11); a second reflector (4) arranged in the accommodation space (11) opposite to the first reflector (3); whereby sunlight (S) is incident into the light outlet (12) and focused by the second reflector (4) and then reflected to the first reflector (3) and then further reflected by the first reflector (3) to the display panel (21), thereby characterized in that a detection board (5), which is arranged in the receiving space (11) and is located relatively far away from the second reflector (4) on the back of the first reflector (3) and is provided with a plurality of light sensor elements (51), a part of the sunlight (S) passing through the first reflector (3) and obtains the light focusing positions of the sunlight (S) projected onto the display panel (21) according to the signal distribution of the plurality of light sensor elements (51) and the radiation intensity according to the signal strength of the plurality of light sensor elements (51). of sunlight (S). head-up display setup claim 1 , wherein the head-up display device further comprises a thermal mirror (6) which is arranged at an arbitrary position in the light path from the display panel (21) to the light outlet (12). head-up display setup claim 1 , wherein the head-up display device further comprises a polarizer (7) which is arranged at an arbitrary position in the light path from the display panel (21) to the light outlet (12). head-up display setup claim 1 , wherein the head-up display device further comprises a fan (8) which is arranged on one side of the display module (2). head-up display setup claim 1 , In which further a temperature detection module (9) in the receiving space (11) of the head-up display device is arranged, wherein the Tempe temperature detection module (9) detects the ambient temperature in the head-up display device. head-up display setup claim 1 wherein the first reflector (3) is a flat mirror or a curved mirror and the second reflector (4) is a concave mirror or a curved mirror. head-up display setup claim 1 , in which the light transmittance of the first reflector (3) is less than 15%. head-up display setup claim 1 , in which the light sensor elements (51) detect visible light or infrared light or visible light and infrared light. Method of operation for the head-up display device according to any one of Claims 1 until 8th , wherein at least one backlighting component (22), a display panel (21), a first reflector (3) and a second reflector (4) are arranged one after the other in the light path of the virtual image display of the head-up display device, the steps of the operating method Include: detecting a portion of the sunlight (S) passing through the first reflector (3) using the plurality of light sensing elements (51) of the detection board (5) to determine a light focusing position and the irradiance of the sunlight (S) projected onto the display panel (21). obtain; estimating the time required for the light focusing point on the display panel (21) to reach a heat resistance limit temperature according to the light focusing position, the irradiance, the backlight brightness of the backlight component (22), and the ambient temperature in the head-up display device; and reducing the backlight brightness of the backlight component (22) or turning off the backlight component (22) before the time is reached. operating procedures claim 9 , in which the time required for a light focusing position on the display panel (21) to reach the heat-resistance limit temperature is calculated using a temperature-time curve or a formula for estimating the temperature, the parameters used in the formula for estimating the temperature irradiance, light focus position, ambient temperature, and backlight brightness. operating procedures claim 9 , in which a plurality of light-focusing positions are defined on the display panel (21), the light-focusing positions being obtained by determining from a read signal value of the plurality of light sensor elements (51) the positions of the distribution center of the light sensor elements (51) whose values are higher than a threshold value, or the positions of the light sensor elements (51) are chosen with the highest values, these positions corresponding to the light focusing positions. A head-up display device comprising a main body (1), wherein an accommodating space (11) and a light outlet (12) are provided inside the main body (1); a display module (2) which is arranged in the receiving space (11) and has a display panel (21) and a backlight component (22); a first reflector (3) which is arranged in the receiving space (11); a second reflector (4) arranged in the accommodation space (11); a thermal mirror (6) placed at any position in the light path from the display panel (21) to the first reflector (3), with an included angle θ of less than 90° and greater than 0° between the mirror surface (61) of the thermal mirror (6) and the light path; whereby sunlight (S) is incident into the light outlet (12) and is focused by the second reflector (4) and then reflected to the first reflector (3) and then further reflected by the first reflector (3) to the thermal mirror (6), wherein part of the sunlight (S) passes through the thermal mirror (6) and then reaches the display panel (21) and the other part of the sunlight (S) is reflected by the thermal mirror (6), characterized in that a detection circuit board (5) installed in receiving space (11) and is located relatively far away from the second reflector (4) on the back of the first reflector (3) and is provided with several light sensor elements (51), part of the sunlight passing through the first reflector (3) (p ). radiation intensity of sunlight (S). head-up display setup claim 12 , wherein the head-up display device further comprises a polarizer (7) which is arranged at an arbitrary position in the light path from the display panel (21) to the light outlet (12). head-up display setup claim 12 , wherein the head-up display device further comprises a fan (8) which is arranged on one side of the display module (2). head-up display setup claim 12 , In which further a temperature detection module (9) in the receiving space (11) of the head-up display device is arranged, wherein the temperature detection module (9) detects the ambient temperature in the head-up display device. head-up display setup claim 12 wherein the first reflector (3) is a flat mirror or a curved mirror and the second reflector (4) is a concave mirror or a curved mirror. head-up display setup claim 12 , in which the light sensor elements (51) detect visible light or infrared light or visible light and infrared light. Method of operation for the head-up display device according to any one of Claims 12 until 17 , wherein at least one backlighting component (22), a display panel (21), a first reflector (3) and a second reflector (4) are arranged one after the other in the light path of the virtual image display of the head-up display device, the steps of the operating method Comprising: detecting part of the sunlight (S) reflected by the thermal mirror (6) arranged between the first reflector (3) and the display panel (21) by means of the plurality of light sensor elements (51) of the detection board (5) to obtaining a light focusing position and the irradiance of the sunlight (S) projected onto the display panel (21); estimating the time required for the light focusing point on the display panel (21) to reach a heat resistance limit temperature according to the light focusing position, the irradiance, the backlight brightness of the backlight component (22), and the ambient temperature in the head-up display device; and reducing the backlight brightness of the backlight component (22) or turning off the backlight component (22) before the time is reached. operating procedures Claim 18 , in which the time required for a light focusing position on the display panel (21) to reach the heat-resistance limit temperature is calculated using a temperature-time curve or a formula for estimating the temperature, the parameters used in the formula for estimating the temperature irradiance, light focus position, ambient temperature, and backlight brightness. operating procedures Claim 18 , in which a plurality of light-focusing positions are defined on the display panel (21), the light-focusing positions being obtained by determining from a read signal value of the plurality of light sensor elements (51) the positions of the distribution center of the light sensor elements (51) whose values are higher than a threshold value, or the positions of the light sensor elements (51) are chosen with the highest values, these positions corresponding to the light focusing positions.

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