WO2023145853A1

WO2023145853A1 - Head-up display device

Info

Publication number: WO2023145853A1
Application number: PCT/JP2023/002572
Authority: WO
Inventors: 正則遠藤; 健人廣木
Original assignee: 日本精機株式会社
Priority date: 2022-01-31
Filing date: 2023-01-27
Publication date: 2023-08-03

Abstract

Provided is a head-up display device with which it is possible to more accurately determine a luminance abnormality of a light source.　This head-up display device (100) comprises: a display (14); a light source (18a); a light source driver IC (72) that outputs a second PWM signal (Spwm2) to the light source (18a); and a microcomputer (71) that outputs a first PWM signal (Spwm1) to the light source driver IC (72), and performs feedback input of the second PWM signal (Spwm2) as a PWM feedback signal (Sfp), wherein the micro-computer (71) includes a luminance abnormality determination unit (71b) which determines that there is a luminance abnormality when a time difference of the PWM feedback signal (Sfp) relative to the first PWM signal (Spwm1) is at least a first allowable time when lighting the light source (18a) at a first luminance, and determines that there is a luminance abnormality when the time difference is at least a second allowable time longer than the first allowable time when lighting the light source (18a) at a second luminance lower than the first luminance.

Description

head-up display device

The present invention relates to a head-up display device.

For example, the head-up display device described in Patent Document 1 includes an LED (Light Emitting Diode), a microcomputer that outputs a first PWM signal and acquires the cathode voltage of the LED, and receives the first PWM signal from the microcomputer, and a driver for lighting the LED by outputting to the LED a second PWM signal obtained by boosting the 1 PWM signal. When this microcomputer determines that a specific point specified by the duty ratio of the signal (cathode voltage) fed back through the smoothing section and the first PWM signal exists within the abnormal high luminance range, the abnormal luminance failure of the LED is detected. To detect.

WO2020/235683

In the configuration described in Patent Document 1, for example, when the LED current is reduced in order to achieve low brightness of the LED, the voltage change of the cathode voltage of the LED becomes dull with respect to the first PWM signal due to the characteristics of the LED. . Therefore, a delay (time difference) occurs between the output first PWM signal and the feedback signal. Therefore, there is room for improvement in accurate determination of luminance abnormality.

The present invention has been made in view of the above-mentioned actual situation, and an object of the present invention is to provide a head-up display device capable of more accurately determining luminance abnormality of a light source.

In order to achieve the above object, a head-up display device according to an aspect of the present invention includes a display, a light source that lights so as to emit light to the display, and a drive signal that causes the light source to light. and a microcomputer that outputs a lighting signal that determines the current value or voltage value of the driving signal to the driver and feeds back the lighting signal or the driving signal as a feedback lighting signal, wherein the microcomputer determines that there is a luminance abnormality when the delay time of the input feedback lighting signal with respect to the output lighting signal is equal to or longer than a first allowable time when lighting the light source at the first luminance, and When it is less than the first allowable time, it is determined that there is no luminance abnormality, and the delay time is longer than the first allowable time when lighting the light source at a second luminance lower than the first luminance. A brightness abnormality determination unit is provided for determining that there is a brightness abnormality when the delay time is equal to or longer than the second allowable time, and determining that there is no brightness abnormality when the delay time is less than the second allowable time.

According to the present invention, in the head-up display device, luminance abnormality of the light source can be determined more accurately.

1 is a schematic diagram of a vehicle equipped with a head-up display device according to an embodiment of the present invention; FIG. 1 is a schematic diagram of a head-up display device according to one embodiment of the present invention; FIG. 1 is a block diagram of a head-up display device according to an embodiment of the invention; FIG. 4A to 4C are diagrams showing waveforms of the first PWM signal, the cathode voltage of the light source, and the PWM feedback signal when there is no luminance abnormality in the normal luminance mode according to one embodiment of the present invention; FIG. 4A and 4B are diagrams showing waveforms of a first PWM signal and a PWM feedback signal when there is luminance abnormality in a normal luminance mode according to an embodiment of the present invention; FIG. 4A to 4C are diagrams showing waveforms of the first PWM signal, the cathode voltage of the light source, and the PWM feedback signal when there is no luminance abnormality in the low luminance mode according to the embodiment of the present invention; FIG. 4A and 4B are diagrams showing waveforms of a first PWM signal and a PWM feedback signal when there is luminance abnormality in a normal luminance mode according to an embodiment of the present invention; FIG. 4 is a flow chart showing the procedure of luminance abnormality determination processing according to one embodiment of the present invention.

An embodiment of a head-up display device according to the present invention will be described with reference to the drawings.
As shown in FIG. 1 , head-up display device 100 is installed in a dashboard of vehicle 200 . The head-up display device 100 emits display light L representing an image toward a windshield 201, which is an example of a projected member of the vehicle 200. As shown in FIG. The display light L is reflected by the windshield 201 and reaches the viewer 1 (mainly the driver of the vehicle 200). Thereby, the virtual image V is displayed so that it can be visually recognized by the viewer 1 .

As shown in FIG. 2, the head-up display device 100 includes a display section 10, a plane mirror 20, a concave mirror 30, a housing 60, and a control section .

The display unit 10 emits display light L representing an image under the control of the control unit 70 . The display unit 10 includes a display 14 and an illumination device 18 .

The plane mirror 20 reflects the display light L emitted by the display unit 10 toward the concave mirror 30 . The concave mirror 30 magnifies and reflects the display light L reflected by the plane mirror 20 toward the windshield 201 (see FIG. 1).
Note that the plane mirror 20 may be a concave mirror.

The housing 60 is made of non-translucent resin or metal and has a substantially hollow rectangular parallelepiped shape. Each component of the head-up display device 100 is housed in the housing 60 .
An opening 61 is formed in the housing 60 at a position facing the windshield 201 . The housing 60 includes a curved plate-shaped window 50 that closes the opening 61 . The window part 50 is made of translucent resin such as acrylic through which the display light L is transmitted.

The display 14 is a TFT (Thin Film Transistor) type liquid crystal display panel controlled by the control unit 70 . The display 14 emits display light L upon receiving light from the illumination device 18 .

The illumination device 18 is located behind the display 14 and illuminates the display 14 with illumination light. The illumination device 18 includes a plurality of light sources 18 a that emit light to the display 14 under the control of the controller 70 . Each light source 18a consists of an LED.

Next, electrical configurations of the display unit 10 and the control unit 70 will be described.
As shown in FIG. 3, the display unit 10 includes a plurality of light sources 18a, a display 14, and a signal conditioning circuit 73. The control unit 70 includes a microcomputer (microcomputer) 71 , a light source driver IC 72 and an input voltage switching circuit 78 .

The input voltage switching circuit 78 is provided between the power supply voltage Vc and the light source driver IC 72, and receives a control signal Sc from the microcomputer 71 and switches between an ON state and an OFF state. When the input voltage switching circuit 78 is on, the power supply voltage Vc is applied to the light source driver IC 72 . The power supply voltage Vc is a voltage used for operating the light source driver IC 72 . When the input voltage switching circuit 78 is in the OFF state, application of the power supply voltage Vc to the light source driver IC 72 is stopped.

The light source driver IC 72 is a switch circuit that receives a power supply voltage Vc and boosts a first PWM (Pulse Width Modulation) signal Spwm1 (lighting signal) from the microcomputer 71 to generate a second PWM signal Spwm2 (drive signal). . The second PWM signal Spwm2 becomes a signal synchronized with the first PWM signal Spwm1. The light source driver IC 72 supplies the light source current Iled to the plurality of light sources 18a via the second PWM signal Spwm2. An anode terminal of the light source 18 a is connected to the light source driver IC 72 . A cathode terminal of the light source 18 a is connected to the microcomputer 71 via the signal adjustment circuit 73 .

The signal adjustment circuit 73 receives the voltage across the light source 18a (the anode voltage and the cathode voltage Vct) and generates the PWM feedback signal Sfp, which is the feedback signal of the second PWM signal Spwm2, from the cathode voltage Vct of the light source 18a. A PWM feedback signal Sfp is output to the microcomputer 71 . The PWM feedback signal Sfp is a signal readable by the microcomputer 71 . The signal adjustment circuit 73 generates a binarized PWM feedback signal Sfp (see FIG. 6(c)) by comparing the cathode voltage Vct of the light source 18a and the threshold value Th (see FIG. 6(b)). The signal conditioning circuit 73 has capacitors, resistors and switching elements, none of which are shown. The signal adjustment circuit 73 actually outputs a PWM feedback signal Sfp obtained by inverting the on and off states of the second PWM signal Spwm2. and the waveform of the PWM feedback signal Sfp without inverting off.

The microcomputer 71 is used as a processing unit such as a CPU (Central Processing Unit) that executes an operation program, a ROM (Read Only Memory) that stores the operation program of this processing unit, and a work area for this processing unit. A RAM (Random Access Memory) is provided.
The microcomputer 71 includes, as functional blocks, a light control section 71a, a luminance abnormality determination section 71b, and a display control section 71c that controls the display device 14. FIG.

The light control unit 71a controls lighting of the light source 18a via the light source driver IC72. The dimming unit 71a receives a required brightness signal Sa that indicates a required brightness from the outside, and turns on the light source 18a via the light source driver IC 72 with the required brightness included in the required brightness signal Sa. The required brightness signal Sa increases in proportion to, for example, an external light intensity detection value indicating ambient brightness included in vehicle information from an in-vehicle ECU (Electronic Control Unit).
When the display unit 10 is powered on, the dimming unit 71a outputs an enable signal Sen to the light source driver IC 72 to permit the light source driver IC 72 to operate. The light adjustment unit 71a disables the operation of the light source driver IC 72 by stopping the output of the enable signal Sen after the luminance abnormality determination described later.

The dimming unit 71a adjusts the luminance of the light source 18a by adjusting the duty ratio of the first PWM signal Spwm1 and the duty ratio of the ADIM (analog dimming input) signal Sadim. The higher the on-duty ratio of the first PWM signal Spwm1, the longer the time (on-time Ton1) during which the light source current Iled is supplied to the light source 18a in one cycle Tc shown in FIG. 4, and the higher the brightness of the light source 18a. The higher the on-duty ratio of the ADIM signal Sadim, the higher the peak current value of the light source current Iled.
The frequency of the first PWM signal Spwm1 is set to, for example, 1 kHz to several hundred kHz. The frequency of the ADIM signal Sadim is set to, for example, several tens of kHz, preferably 50 kHz.

When the requested luminance is within the normal luminance range, the dimming unit 71a enters the normal luminance mode and generates the first PWM signal Spwm1 having a duty ratio corresponding to the requested luminance while fixing the duty ratio of the ADIM signal Sadim to a specified value. do. In the normal brightness mode, the higher the required brightness, the higher the on-duty ratio of the first PWM signal Spwm1 is set.

When the required brightness is within the low brightness range set to be lower than the normal brightness range, the dimming unit 71a enters the low brightness mode, fixing the duty ratio of the first PWM signal Spwm1 to the lower limit, and adjusting the required brightness. to generate an ADIM signal Sadim having a duty ratio corresponding to . In the low luminance mode, the higher the required luminance is, the higher the on-duty ratio of the ADIM signal Sadim is set. The lower limit of the on-duty ratio of the first PWM signal Spwm1 is set to 0.2%, for example.

Based on the delay time of the PWM feedback signal Sfp input to the microcomputer 71 with respect to the first PWM signal Spwm1 output from the microcomputer 71, the luminance abnormality determination unit 71b determines whether there is an abnormality in the brightness of the light source 18a.

As shown in FIGS. 4 to 7, the luminance abnormality determination unit 71b determines luminance abnormality using allowable times Tk1 and Tk2 having different lengths in the low luminance mode and the normal luminance mode. The permissible time Tk2 in the low luminance mode (see FIGS. 6 and 7) is set longer than the permissible time Tk1 in the normal luminance mode (see FIGS. 4 and 5).
For example, in the normal luminance mode, as shown in FIG. 5, the luminance abnormality determination unit 71b determines that the luminance is It is determined that there is an abnormality, and as shown in FIG. 4, when the time difference ΔT is less than the allowable time Tk1, it is determined that there is no luminance abnormality. Further, in the low luminance mode, the luminance abnormality determination unit 71b determines that there is luminance abnormality when the time difference ΔT is equal to or greater than the allowable time Tk2 as shown in FIG. When the time is less than Tk2, it is determined that there is no luminance abnormality.
The time difference ΔT is the time difference between the timings at which the first PWM signal Spwm1 and the PWM feedback signal Sfp are switched from ON to OFF, and corresponds to the OFF delay time of the PWM feedback signal Sfp based on the first PWM signal Spwm1.

Next, luminance abnormality determination processing executed by the microcomputer 71 will be described with reference to the flowchart of FIG. This luminance abnormality determination process is repeatedly executed while the microcomputer 71 controls the lighting of the light source 18a.
The dimming unit 71a determines whether or not the mode is the low luminance mode (step S101). When determining that the light control unit 71a is in the low luminance mode (step S101; YES), the time difference ΔT between the on-time Ton1 of the first PWM signal Spwm1 and the on-time Ton2 of the PWM feedback signal Sfp is allowed as luminance abnormality determination processing. It is determined whether or not the time is equal to or greater than time Tk2 (step S102). As illustrated in FIG. 7, when the light adjustment unit 71a determines that the time difference ΔT is equal to or greater than the allowable time Tk2 (step S102; YES), the light source 18a is extinguished (step S103) assuming that there is luminance abnormality. The luminance abnormality determination process is terminated. On the other hand, as illustrated in FIG. 6, when the light control unit 71a determines that the time difference ΔT is less than the allowable time Tk2 (step S102; NO), it determines that there is no luminance abnormality, and continues lighting of the light source 18a. This luminance abnormality determination process is terminated.

When the dimming unit 71a determines that the mode is not the low luminance mode, that is, the normal luminance mode (step S101; NO), the time difference ΔT between the ON time Ton1 of the first PWM signal Spwm1 and the ON time Ton2 of the PWM feedback signal Sfp is allowed. It is determined whether or not the time is equal to or greater than time Tk1 (step S104). As illustrated in FIG. 5, if the light adjustment unit 71a determines that the time difference ΔT is equal to or greater than the allowable time Tk1 (step S104; YES), the light source 18a is extinguished (step S103) assuming that there is a luminance abnormality. The luminance abnormality determination process is terminated. On the other hand, as illustrated in FIG. 4, when the light adjustment unit 71a determines that the time difference ΔT is less than the allowable time Tk1 (step S104; NO), it determines that there is no luminance abnormality, and continues lighting the light source 18a. This luminance abnormality determination process is terminated.
Further, the display control unit 71c ends the display on the display 14 when the light source 18a is turned off.

In order to turn off the light source 18a in step S103, the light control unit 71a sequentially executes steps S103a, S103b, and S103c, for example. Specifically, the dimming unit 71a stops outputting the enable signal Sen to the light source driver IC 72 (step S103a), then stops outputting the ADIM signal Sadim to the light source driver IC 72 (step S103b), and then , the input voltage switching circuit 78 is turned off through the control signal Sc (step S103c).
This is the end of the description of the brightness abnormality determination process.

Next, the reason why the permissible times Tk1 and Tk2 are switched according to the brightness will be explained.
As shown in FIGS. 6A and 6B, when the first PWM signal Spwm1 is switched from on to off (for example, time t1), the cathode voltage Vct of the light source 18a does not drop due to the characteristics of the light source 18a. In other words, the speed of voltage drop slows down, so the timing at which the PWM feedback signal Sfp turns off is delayed with respect to the timing at which the first PWM signal Spwm1 turns off. This delay is particularly noticeable at low luminance. In order to prevent erroneous determination of luminance abnormality due to this delay, the permissible time Tk2 in the low luminance mode is set longer than the permissible time Tk1 in the normal luminance mode.

For example, as a comparative example, when the permissible time Tk1 is fixed regardless of the luminance, as shown in FIG. As described above, it is erroneously determined that there is luminance abnormality. On the other hand, as a comparative example, when the permissible time Tk2 is fixed regardless of the luminance, erroneous determination in the low luminance mode is avoided, but in the normal luminance mode, the permissible time Tk2 is too long, so that it is determined that the luminance is abnormal. judgment is delayed. As a result, the brightness becomes excessively high, which may dazzle the driver. Note that when the luminance is low, the driver is less likely to be dazzled even if the permissible time Tk2 is long.
Therefore, by switching the permissible times Tk1 and Tk2 according to the luminance as in the present embodiment, it is possible to suppress erroneous judgments at low luminance and realize rapid luminance abnormality judgment at normal luminance including high luminance. .

Next, a method for setting the permissible times Tk1 and Tk2 will be described while exemplifying specific numerical values.
The maximum value of the on-duty ratio of the first PWM signal Spwm1 in the normal luminance mode is 92.5%. At this time, as a result of actual measurement, the on-time Ton1 of the first PWM signal Spwm1 is 925 μs, the on-time Ton2 of the PWM feedback signal Sfp is 934 μs, and the time difference ΔT is 9 μs.
Further, in the low luminance mode, the on-duty ratio of the first PWM signal Spwm1 is fixed at the minimum value of 0.2%, and the peak current value of the light source current Iled is varied by adjusting the duty ratio of the ADIM signal Sadim. . At this time, as a result of actual measurement, the on-time Ton1 of the first PWM signal Spwm1 is 2 μs, the on-time Ton2 of the PWM feedback signal Sfp is 62 μs, and the time difference ΔT is 60 μs. Thus, in the low-luminance mode, the cathode voltage Vct of the light source 18a decreases less, so the time difference ΔT in the low-luminance mode is larger than the time difference ΔT in the normal luminance mode.
Based on the above actual measurement results, the permissible time Tk1 is set to a value larger than 9 μs and smaller than 60 μs, for example, 45 μs to 55 μs, preferably 50 μs. Since the maximum time difference ΔT in the normal luminance mode is about 30 μs, the permissible time Tk1 is preferably set to a value with a margin of about 30 μs. The permissible time Tk1 is set shorter than the time required for the cathode voltage Vct of the light source 18a to reach a steady state after the first PWM signal Spwm1 is turned on in the low luminance mode.
The allowable time Tk2 is set to a value greater than 60 μs, eg, 100 μs to 300 μs, preferably 200 μs. The permissible time Tk2 is set to a time during which erroneous determination can be suppressed in consideration of the temperature characteristics of the light source 18a or the signal adjustment circuit 73, component characteristics, and the like. Even if the permissible time Tk2 is set longer than the permissible time Tk1, the driver is less likely to be dazzled.

(effect)
According to the embodiment described above, the following effects are obtained.
(1) The head-up display device 100 includes the display 14, the light source 18a that lights so as to emit light to the display 14, and the second PWM signal Spwm2, which is an example of a drive signal for lighting the light source 18a. 18a, and a first PWM signal Spwm1, which is an example of a lighting signal that determines the current value or voltage value of the second PWM signal Spwm2, is output to the light source driver IC 72, and the second PWM signal Spwm2 is output to the light source driver IC 72. and a microcomputer 71 for feedback input as a PWM feedback signal Sfp, which is an example of a feedback lighting signal. When the microcomputer 71 lights the light source 18a at the first luminance (normal luminance), the time difference ΔT, which is an example of the delay time of the input PWM feedback signal Sfp with respect to the output first PWM signal Spwm1, is an example of the first allowable time. When the time difference .DELTA.T is less than the allowable time Tk1, it is determined that there is no luminance abnormality, and the light source 18a is turned on at a second luminance lower than the first luminance. When the time difference ΔT is longer than the allowable time Tk2, which is an example of a second allowable time longer than the allowable time Tk1, it is determined that there is a luminance abnormality, and when the time difference ΔT is less than the allowable time Tk2, there is no luminance abnormality. A luminance abnormality determination unit 71b is provided for determining that
According to this configuration, when the luminance is low, the permissible time Tk2, which is longer than the permissible time Tk1 when the normal luminance is used, is used to determine whether the luminance is abnormal. Therefore, when the luminance is low, erroneous determination that there is luminance abnormality due to the cathode voltage Vct of the light source 18a being dull is suppressed. Therefore, it is possible to more accurately determine the luminance abnormality of the light source 18a.

(2) The luminance abnormality determination unit 71b acquires the delay time from the time difference ΔT between the ON time Ton1 of the first PWM signal Spwm1 and the ON time Ton2 of the PWM feedback signal Sfp. The microcomputer 71 continues turning on the light source 18a when the luminance abnormality determining section 71b determines that there is no luminance abnormality, and turns off the light source 18a when the luminance abnormality determining section 71b determines that there is luminance abnormality.
According to this configuration, the delay time can be obtained easily.

(3) The permissible time Tk1 is set to a time shorter than the time difference ΔT between the ON time Ton1 of the first PWM signal Spwm1 and the ON time Ton2 of the PWM feedback signal Sfp when the light source 18a is lit at the second luminance (low luminance). be done.
According to this configuration, the permissible time Tk1 is shortened at the time of normal luminance, and it is quickly determined that there is luminance abnormality. This prevents the driver from being dazzled.

(4) The allowable time Tk1 is required from when the first PWM signal Spwm1 is input until the voltage and current of both terminals of the light source 18a reach a steady state when the light source 18a is lit at the second luminance (low luminance). set to a time shorter than the hour.
According to this configuration, the permissible time Tk1 is shortened at the time of normal luminance, and it is quickly determined that there is luminance abnormality. This prevents the driver from being dazzled.

The present invention is not limited by the above embodiments and drawings. Modifications (including deletion of components) can be made as appropriate without changing the gist of the present invention. An example of modification will be described below. Each of the following modifications may be combined as appropriate.

(Modification)
In the process of turning off the light source 18a after the luminance abnormality determination in the above-described embodiment, the process is executed in the order of step S103a→step S103b→step S103c, but this order can be changed as appropriate. Moreover, steps S103a, S103b, and S103c may be executed simultaneously.
Furthermore, any two of the three steps S103a, S103b, and S103c may be omitted.
Further, the output of the first PWM signal Spwm1 may be stopped as the extinguishing process.

In the above embodiment, the dimming unit 71a determines whether or not there is a luminance abnormality based on the comparison between the time difference ΔT between the ON times Ton1 and Ton2 and the allowable times Tk1 and Tk2. , the presence or absence of luminance abnormality may be determined based on the time difference between the OFF times.

In the above embodiment, two permissible times Tk1 and Tk2 with different lengths are set between the low luminance mode and the normal luminance mode. may be set. Alternatively, the dimming unit 71a may derive the permissible time from the required luminance using a calculation formula, and use the derived permissible time to determine the presence or absence of luminance abnormality.

In the above embodiment, the display control unit 71c may switch the display 14 to the non-transmissive state (black display state) when the luminance abnormality determination unit 71b determines that the light source 18a has abnormality in luminance. As a result, dazzling the viewer 1 viewing the virtual image V is suppressed.

In the above embodiment, the feedback lighting signal is the PWM feedback signal Sfp of the second PWM signal Spwm2, but is not limited to this, and may be the PWM feedback signal Sfp of the first PWM signal Spwm1. In this case, the PWM feedback signal Sfp may be a signal that has passed through the light source driver IC 72 .
Also, the signal conditioning circuit 73 may be omitted.

In the above embodiment, when the microcomputer 71 determines that the light source 18a has an abnormality in luminance, it turns off the plurality of light sources 18a. Alternatively, the viewer 1 may be notified that there is a luminance abnormality through notification means such as an indicator.

In the above embodiment, the display 14 was a liquid crystal display panel, but it is not limited to this, and may be a reflective display such as a DMD (Digital Micromirror Device) element.

Although the head-up display device 100 is mounted on the vehicle 200 in the above embodiment, it may be mounted on a vehicle other than the vehicle 200, such as an airplane or a ship. Further, the projected member is not limited to the windshield 201, and may be a dedicated combiner.

1 Viewer 10 Display unit 14 Display unit 18 Lighting device 18a Light source 20 Plane mirror 30 Concave mirror 50 Window unit 60 Housing 61 Opening 70 Control unit 71 Microcomputer

71a Dimming unit

71b Judging unit 71c Display control unit 72 Light source driver IC 73 Signal adjustment circuit 78 Input voltage switching circuit 100 Head-up display device 200 Vehicle 201 Windshield L Display light ΔT Time difference V Virtual image Sa Required luminance signal Sc Control signal Tc One cycle Vc Power supply voltage Th Threshold values Tk1, Tk2 Allowable time Sen Enable signal Sfp PWM feedback signal Vct Cathode voltages Ton1, Ton2 ON time Iled Light source current Spwm1 First PWM signal Spwm2 Second PWM signal Sadim ADIM signal

Claims

a display;
a light source that lights so as to emit light to the indicator;
a driver that outputs a drive signal to the light source to turn on the light source;
a microcomputer that outputs a lighting signal that determines the current value or voltage value of the driving signal to the driver and feeds back the lighting signal or the driving signal as a feedback lighting signal;
When lighting the light source at a first luminance, the microcomputer determines that there is a luminance abnormality when a delay time of the input feedback lighting signal with respect to the output lighting signal is equal to or longer than a first allowable time, and determines that the delay occurs. When the time is less than the first allowable time, it is determined that there is no luminance abnormality, and when the light source is lit at a second luminance lower than the first luminance, the delay time is longer than the first allowable time. a luminance abnormality determination unit that determines that there is a luminance abnormality when the delay time is longer than a second allowable time, and determines that there is no luminance abnormality when the delay time is less than the second allowable time;
Head-up display device.
The luminance abnormality determination unit acquires the delay time from the time difference between the ON time of the lighting signal and the ON time of the feedback lighting signal,
The microcomputer continues to turn on the light source when the luminance abnormality determination unit determines that there is no luminance abnormality, and turns off the light source when the luminance abnormality determination unit determines that there is a luminance abnormality.
The head-up display device according to claim 1.
The first allowable time is set to a time shorter than the time difference between the ON time of the lighting signal and the ON time of the feedback lighting signal when the light source is lit at the second luminance.
The head-up display device according to claim 1 or 2.