JP2022037466A - Vehicular display device - Google Patents

Abstract

To reduce a possibility that a display image is too bright for a user due to an abnormality.SOLUTION: A vehicular display device projects a display image on a windshield and includes: a case; a first circuit board housed in the case; a second circuit board for a back light which is housed in the case and electrically connected with the first circuit board; a light source provided on the second circuit board; a temperature sensor for the light source provided on the second circuit board; and a processing device mounted on the first circuit board. The processing device controls the light source based on a relationship between temperature information from the temperature sensor for the light source and reference temperature information indicating a temperature of a portion different from the second circuit board in the case.SELECTED DRAWING: Figure 2

Description

The present disclosure relates to a vehicle display device.

In a vehicle display device that projects a display image on a windshield, a technique for changing the output (emission brightness) of a light emitting diode for the backlight of a display according to the amount of external light (ambient brightness) is known. There is.

Japanese Unexamined Patent Publication No. 2008-083429

By the way, if the output of the light emitting diode becomes excessive with respect to the control target value (set value) due to some abnormality, the display image may be too bright for the user.

Therefore, it is an object of the present disclosure to reduce the possibility that the displayed image is too bright for the user due to an abnormality.

On one side, in a vehicle display device that projects a display image onto a windshield.
With the case
The first circuit board housed in the case and
A second circuit board for the backlight, which is housed in the case and electrically connected to the first circuit board.
The light source provided on the second circuit board and
A temperature sensor for a light source provided on the second circuit board and
Including the processing device mounted on the first circuit board.
The processing device controls the light source based on the relationship between the temperature information from the temperature sensor for the light source and the reference temperature information representing the temperature of a portion different from the second circuit board in the case. Display device is provided.

According to the present disclosure, it is possible to reduce the possibility that the displayed image is too bright for the user due to the abnormality.

It is a figure which shows roughly the vehicle-mounted state of the head-up display by one Embodiment in the vehicle side view. It is a schematic diagram which shows the structure of a head-up display. It is a schematic diagram which shows the control system including a circuit board and a light source board. It is a figure which shows an example of the function realized by the microcomputer of the circuit board. It is a schematic flowchart which shows the operation example of a microcomputer.

Hereinafter, each embodiment will be described in detail with reference to the accompanying drawings.

FIG. 1 is a diagram schematically showing a vehicle-mounted state of the head-up display H according to one embodiment in a vehicle side view. FIG. 2 is a schematic view showing the configuration of the head-up display H.

In the head-up display H, as shown in FIG. 1, when the windshield WS is irradiated with the display light, the display obtained by the irradiation is in front of the windshield WS for the driver driving the vehicle VC. Image (virtual image display) VI can be seen. As a result, the driver can visually recognize the display image VI by superimposing it on the landscape in front. Therefore, the driver can grasp the vehicle information and the like in a mode in which the line-of-sight movement is small as compared with the case of looking at the meter in the instrument panel 9, and the convenience and safety are improved. In the modified example, a combiner or the like may be used instead of the windshield WS.

FIG. 2 is a diagram schematically showing the configuration inside the instrument panel 9 in the head-up display H in a side view.

The head-up display H (an example of a display device for a vehicle) houses a display unit 1, a plane mirror 2, a concave mirror 3, and a circuit board 4 (an example of a first circuit board) in a case 5.

The display unit 1 includes a light source board 11 (an example of a second circuit board) on which an LED 110 (light emitting diode) for a backlight serving as a light source is mounted, a lens 12 that makes light emitted from the LED 110 substantially parallel light. It has a light source type liquid crystal panel 13 illuminated by substantially parallel light emitted from the lens 12. The display unit 1 emits the display light L toward the plane mirror 2.

The plane mirror 2 includes a flat plate-shaped resin substrate and a reflective layer formed on the flat surface of the resin substrate. The resin substrate is made of a resin such as polycarbonate. The reflective layer is formed by depositing a metal such as aluminum on a flat surface of a resin substrate. The plane mirror 2 reflects the display light L emitted from the display unit 1 toward the concave mirror 3.

The concave mirror 3 is composed of a resin substrate having a concave surface and a reflective layer formed on the concave surface of the resin substrate. The resin substrate is made of a resin such as polycarbonate. The reflective layer is formed by depositing a metal such as aluminum on the concave surface of the resin substrate. The concave mirror 3 reflects the display light L reflected by the plane mirror 2 toward the windshield WS of the vehicle.

The circuit board 4 is a control board that controls the entire head-up display H. The circuit board 4 is arranged at different positions in the case 5 with respect to the light source board 11 described above, and is partitioned by the partition wall portion 57.

A microcomputer 41 (an example of a processing device) or the like is mounted on the circuit board 4 (see FIG. 3). Further, a female connector 40 is mounted on the circuit board 4.

A male connector 60 that electrically connects to a harness 6 having a signal line for transmitting vehicle information and a power supply line for supplying battery power of the vehicle is inserted into the female connector 40, and vehicle information is input to the circuit board 4. To. The circuit board 4 causes the display unit 1 to emit the vehicle information input from the harness 6 as the display light L.

The case 5 includes a first case 50, a cover 51, a second case 52, and a third case 53, and includes a first accommodating portion 54, a second accommodating portion 55, and a third accommodating portion 56. It is an instrument box to have.

A plane mirror 2 and a concave mirror 3 are housed in the first storage portion 54. The display unit 1 is housed in the second storage unit 55. The circuit board 4 is accommodated in the third accommodating portion 56.

The first case 50 is a case made of a resin such as polypropylene. In the first case 50, an incident port 50a for taking in the display light L emitted by the display unit 1 into the first accommodating portion 54 and an exit port 50b for emitting the display light L reflected by the concave mirror 3 to the outside of the case 5 are provided. It is formed.

The cover 51 is a cover made of a translucent resin such as acrylic resin in the form of a film. The cover 51 covers the exit port 50b and prevents dust, moisture, and the like from entering the first accommodating portion 54 from the exit port 50b.

The second case 52 is a case in which a fin shape is formed on the outside with a metal such as aluminum. The second case 52 engages with the first case 50 to cover the display unit 1 accommodated in the second accommodating portion 55, and as a radiator that dissipates heat from the LED 110 on the light source substrate 11 of the display unit 1. It also has the function of.

The third case 53 is a case made of a resin such as polypropylene. The third case 53 engages with the first case 50 and covers the circuit board 4 accommodated in the third accommodating portion 56.

FIG. 3 is a schematic view showing a control system including a circuit board 4 and a light source board 11. FIG. 3 shows an external light sensor 70 and an in-vehicle unit 72 connected to the circuit board 4 in addition to the circuit board 4 and the light source board 11.

The external light sensor 70 is provided in a vehicle on which the head-up display H is mounted (for example, near the upper part of the windshield WS), and detects the brightness around the vehicle. Specifically, the external light sensor 70 generates an electric signal according to the amount and intensity of incident light.

The vehicle-mounted unit 72 may be connected to the circuit board 4 via the harness 6 as described above. The in-vehicle unit 72 is, for example, in the form of an ECU (Electronic Control Unit). The in-vehicle unit 72 may supply various vehicle information such as vehicle speed information and other setting information by the user regarding the brightness related to the display image VI of the head-up display H to the circuit board 4.

As shown in FIG. 3, a microcomputer 41, an LED driver 42, a communication circuit 43, and a thermistor 44 are mounted on the circuit board 4.

The microcomputer 41 controls the LED 110 via the LED driver 42 based on various information obtained via the communication circuit 43 and the thermistor 44. The microcomputer 41 sets a drive duty and gives a drive signal (PWM signal) corresponding to the set drive duty to the LED driver 42. Details of the functions of the microcomputer 41 will be described later with reference to FIGS. 4 and later.

The LED driver 42 drives the LED 110 on the light source substrate 11 based on the drive signal from the microcomputer 41.

The communication circuit 43 communicates with the vehicle-mounted unit 72 via, for example, a vehicle network compliant with CAN (controller area network) or the like. As described above, the communication circuit 43 acquires, for example, the setting information by the user regarding the brightness related to the display image VI of the head-up display H.

The thermistor 44 generates an electric signal according to the ambient temperature. The temperature information detected by the thermistor 44 functions as a reference temperature for detecting an excessive rise in the temperature of the LED 110. That is, as will be described later, the thermistor 44 functions as a temperature sensor for a reference temperature, and is hereinafter also referred to as a "reference temperature thermistor 44" for the sake of distinction.

An LED 110 and a thermistor 112 (referred to as "light source thermistor 112" for distinction) are mounted on the light source substrate 11.

The LED 110 functions as a backlight of the display unit 1. As described above, the LED 110 is driven by the LED driver 42 via the circuit board 4.

The light source thermistor 112 generates an electric signal according to the ambient temperature. The temperature information detected by the light source thermistor 112 functions as information for detecting a situation in which the output of the LED 110 should be restricted, together with the temperature information detected by the reference temperature thermistor 44.

FIG. 4 is a diagram showing an example of a function realized by the microcomputer 41 of the circuit board 4.

As shown in FIG. 4, the microcomputer 41 of the circuit board 4 includes a drive duty setting unit 411, a drive limiting unit 412, and a limiting threshold map storage unit 414. The drive duty setting unit 411 and the drive limiting unit 412 can be realized by the CPU (Central Processing Unit) of the microcomputer 41 executing a program in the memory. Further, the limiting threshold map storage unit 414 may be realized by the memory of the microcomputer 41 (for example, ROM: Read Only Memory).

The drive duty setting unit 411 sets the drive duty based on the sensor information from the external light sensor 70 and the setting information from the vehicle-mounted unit 72. For example, the drive duty setting unit 411 sets the drive duty so that the output (emission brightness) of the LED 110 increases as the brightness around the vehicle becomes brighter. At this time, the drive duty setting unit 411 sets (corrects) the drive duty for each user as appropriate based on the setting information. The details of the drive duty setting method are arbitrary, and may be realized by other methods.

The drive limiting unit 412 monitors an abnormality in the drive system of the LED 110, and when a predetermined abnormality is detected, reduces or stops the output of the LED 110. The abnormality in the drive system of the LED 110 may be an abnormality on the downstream side of the microcomputer 41, and the output of the LED 110 becomes excessive compared to the set value (the drive duty set by the drive duty setting unit 411). including. That is, it includes an abnormality that the LED 110 is driven with a drive duty higher than the drive duty set by the drive duty setting unit 411. For example, the drive duty set by the drive duty setting unit 411 is 70%, whereas the LED 110 is driven with a drive duty of 100%.

In this embodiment, as an example, the drive limiting unit 412 includes a temperature information acquisition unit 4120, a threshold value setting unit 4121, an abnormality determination unit 4122, and a restriction processing unit 4123.

The temperature information acquisition unit 4120 acquires temperature information from the light source thermistor 112 and temperature information from the reference temperature thermistor 44. The temperature information from the light source thermistor 112 represents the temperature of the LED 110 as described above, and the temperature information from the reference temperature thermistor 44 represents the temperature around the circuit board 4 in the case 5 as described above. show.

The threshold value setting unit 4121 sets the threshold value with reference to the limit threshold value map stored in the limit threshold value map storage unit 414. The limiting threshold map storage unit 414 stores, for example, a limiting threshold (hereinafter, also simply referred to as “threshold”) in association with the drive duty. In this case, the threshold value may be associated with each drive duty in such a manner that the drive duty increases (that is, the power consumption increases). The threshold value setting unit 4121 sets a threshold value corresponding to the drive duty based on the drive duty set by the drive duty setting unit 411 with reference to the threshold value map for limitation.

The abnormality determination unit 4122 is determined based on the temperature information from the light source thermistor 112, the temperature information from the reference temperature thermistor 44 (an example of the reference temperature information), and the threshold value set by the threshold value setting unit 4121. Determine if there is an abnormality. Specifically, in the abnormality determination unit 4122, the value obtained by subtracting the temperature information from the reference temperature thermistor 44 from the temperature information from the light source thermistor 112 (hereinafter referred to as “temperature difference value”) exceeds the threshold value. Determine if it is. When it is determined that the temperature difference value exceeds the threshold value, the abnormality determination unit 4122 generates information indicating that a predetermined abnormality has been detected. In this embodiment, as an example, the abnormality determination unit 4122 sets the abnormality flag to “1” as information indicating that a predetermined abnormality has been detected.

The restriction processing unit 4123 executes a restriction process for reducing or stopping the output of the LED 110 when the abnormality determination unit 4122 determines that the temperature difference value exceeds the threshold value (that is, when the abnormality flag is “1”). do.

The above-mentioned limiting threshold map is stored in the limiting threshold map storage unit 414. In this embodiment, the threshold value is associated with the drive duty described above. At this time, the threshold value associated with a certain drive duty is larger than the upper limit of the range of temperature difference values that can be taken when the LED 110 is driven with the drive duty under the condition that the drive system of the LED 110 is normal. , Set high. As a result, under the condition that the drive system of the LED 110 is normal, the possibility that the abnormality determination unit 4122 sets the abnormality flag to "1" (that is, the possibility of erroneous determination) can be reduced, and the determination accuracy can be improved. .. The limiting threshold map may be adapted by a test or a simulation, and may be updated by machine learning or the like during operation. Further, the threshold map for limitation may be in the form of a function or the like instead of the map format, or may be linearly interpolated. Further, the limiting threshold map may be set for each other condition such as the temperature inside the vehicle. Further, the threshold map for limitation may be replaced with an algorithm based on artificial intelligence. In this case, it can be realized by implementing a convolutional neural network obtained by machine learning. In machine learning, for example, using actual data related to various temperature information, weights of a convolutional neural network and the like that maximize the determination accuracy by the abnormality determination unit 4122 are learned.

By the way, in the case of the head-up display H, the brightness of the display image VI may be lower than that in the daytime when traveling in a dark place such as at night, and if it is too bright, the driver may feel glare.

In this regard, in this embodiment, as described above, the display brightness is adjusted by controlling the current flowing through the backlight LED 110 of the liquid crystal panel 13 of the head-up display H according to the ambient brightness such as daytime and nighttime. Has been done. As a result, the LED 110 is turned on with an appropriate emission brightness according to the ambient brightness, and it is possible to effectively support the driver's information acquisition (information acquisition from the display image VI).

However, if some abnormality occurs in the drive system of the LED 110, the LED 110 may not be turned on with an appropriate emission brightness according to the brightness as described above, and the driver's information acquisition (information acquisition from the display image VI) is effective. There is a risk that we will not be able to provide support. For example, when the LED 110 is driven with a drive duty higher than the drive duty set by the drive duty setting unit 411 due to an abnormality when traveling in a dark place such as at night, the display image VI causes the driver to dazzle. You may feel it.

In this regard, according to the present embodiment, as described above, when a predetermined abnormality is detected by the abnormality determination unit 4122, a restriction process for reducing or stopping the output of the LED 110 is executed. As a result, even if some abnormality occurs in the drive system of the LED 110, the possibility that the display image VI that the driver can feel glare can be effectively reduced.

Further, according to the present embodiment, as described above, the presence or absence of a predetermined abnormality is monitored by using not only the temperature information from the light source thermistor 112 but also the temperature information from the reference temperature thermistor 44. ..

Here, as described above, the circuit board 4 and the light source board 11 are arranged at different positions in the case 5 and are partitioned by the partition wall portion 57, and therefore, from the light source thermistor 112. Although the temperature information and the temperature information from the reference temperature thermistor 44 correlate with each other, they have a significant difference. Specifically, the temperature information from the light source thermistor 112 tends to be substantially higher than the temperature information from the reference temperature thermistor 44 by the temperature corresponding to the calorific value of the LED 110. Therefore, if the temperature information from the light source thermistor 112 is significantly higher than the temperature information from the reference temperature thermistor 44, which is the temperature corresponding to the calorific value of the current LED 110, some abnormality occurs. There is a high possibility that it is. Therefore, by monitoring the presence or absence of a predetermined abnormality based on the temperature difference value which is such a difference, the presence or absence of a predetermined abnormality can be accurately determined.

In this embodiment, the temperature information from the reference temperature thermistor 44 mounted on the circuit board 4 is used as the reference temperature when deriving the temperature difference value, but the present invention is not limited to this. For example, information on a thermistor that may be provided at another location in the case 5 away from the light source substrate 11 may be used. Alternatively, the temperature inside the case 5 may be calculated (estimated) from the temperature inside the vehicle, sensor information from the sunshine sensor, or the like, and in this case, the calculated value of the temperature may be used as the reference temperature.

Further, in the present embodiment, the microcomputer 41 may further include another drive limiting unit different from the drive limiting unit 412. In this case, the other drive limiting unit executes, for example, a limiting process for reducing or stopping the output of the LED 110 when the temperature information from the light source thermistor 112 exceeds a predetermined temperature. In such a configuration, the drive limiting unit 412 may function only in a situation where the other drive limiting unit is not functioning.

Next, an operation example of the microcomputer 41 will be described with reference to FIG.

FIG. 5 is a schematic flowchart showing an operation example of the microcomputer 41. The process shown in FIG. 5 may be repeatedly executed at predetermined intervals, for example, in the on state of the vehicle (for example, the on state of the ignition switch).

In step S500, the microcomputer 41 acquires the temperature information from the light source thermistor 112 and the temperature information from the reference temperature thermistor 44.

In step S502, the microcomputer 41 determines whether or not the abnormality flag is “0”. The anomaly flag is as described above. If the determination result is "YES", the process proceeds to step S504, and if not, the process proceeds to step S514.

In step S504, the microcomputer 41 sets the threshold value of the current cycle based on the drive duty before the previous cycle. For example, the microcomputer 41 calculates the average value of the drive duty in the latest predetermined number of cycles, and obtains the threshold value associated with the average value from the limiting threshold map.

In step S506, the microcomputer 41 calculates the temperature difference value based on each temperature information obtained in step S500.

In step S508, the microcomputer 41 determines whether or not the temperature difference value obtained in step S506 exceeds the threshold value set in step S504. If the determination result is "YES", it is determined that a predetermined abnormality has been detected, and the process proceeds to step S510. In other cases, the process proceeds to step S512.

In step S510, the microcomputer 41 sets the abnormality flag to “1” and stops the output of the LED 110. That is, the microcomputer 41 sets the abnormality flag to "1" and starts the restriction process. If the drive duty in the previous cycle is relatively high, the output of the LED 110 may be reduced instead of stopping the output of the LED 110. For example, the drive duty of the LED 110 may be set to a minimum value. When the abnormality flag is set to "1", the microcomputer 41 may generate diagnostic information indicating that a predetermined abnormality has been detected as another process. When step S510 is completed, the process proceeds to step S518.

In step S512, the microcomputer 41 controls the LED 110 according to a normal control mode (that is, performs normal control without restriction processing). Specifically, as described above, the microcomputer 41 calculates and sets the drive duty according to the ambient brightness based on the sensor information from the external light sensor 70 and the like, and based on the set drive duty. , Drives the LED 110.

In step S514, the microcomputer 41 determines whether or not the reset condition of the abnormality flag is satisfied. The reset condition of the abnormality flag is arbitrary, but may be satisfied, for example, when the temperature difference value is equal to or less than a predetermined value smaller than the threshold value. If the determination result is "YES", the process proceeds to step S516, and if not, the process proceeds to step S518.

In step S516, the microcomputer 41 resets the abnormality flag to “0”. After step S516, the process may proceed to step S512.

In step S518, the microcomputer 41 maintains the output of the LED 110 in a stopped or lowered state by maintaining the limiting process.

In this way, according to the process shown in FIG. 5, the presence or absence of a predetermined abnormality can be monitored based on the temperature difference value at a predetermined cycle, and when a predetermined abnormality is detected, the limiting process can be started promptly. ..

By the way, the inconvenience that the driver feels glare in the display image VI because the emission brightness of the LED 110 becomes too high than the appropriate emission brightness according to the ambient brightness due to a predetermined abnormality. Is likely to occur in an environment where the ambient brightness is relatively low (for example, at night).

Therefore, the process shown in FIG. 5 may be executed only in an environment where the ambient brightness is relatively low (for example, at night). In this case, it is possible to reduce the inconvenience caused by the predetermined abnormality as described above while reducing the processing load.

Although each embodiment has been described in detail above, the present invention is not limited to a specific embodiment, and various modifications and changes can be made within the scope of the claims. It is also possible to combine all or a plurality of the components of the above-described embodiment.

For example, in the above-described embodiment, the threshold value setting unit 4121 sets the threshold value in a manner that changes according to the drive duty, but the threshold value is not limited to this. For example, the threshold value may be a fixed value.

1 Display unit 2 Planar mirror 3 Concave mirror 4 Circuit board 5 Case 6 Harness 9 Instrument panel 11 Light source board 110 LED
12 Lens 13 Liquid crystal panel 40 Female connector 41 Microcomputer 42 LED driver 43 Communication circuit 44 Reference temperature thermistor 50 First case 50a Inlet port 50b Outlet port 51 Cover 52 Second case 53 Third case 54 First housing 55 Second Accommodating unit 56 3rd accommodating unit 57 Partition wall unit 60 Male connector 70 External light sensor 72 In-vehicle unit 112 Thermistor for light source 411 Drive duty setting unit 412 Drive limiting unit 414 Restriction threshold map storage unit 4120 Temperature information acquisition unit 4121 Threshold setting unit 4122 Abnormality determination unit 4123 Restriction processing unit H Head-up display L Display light VC Vehicle VI display image WS Windshield

Claims (4)

In a vehicle display device that projects a display image on a windshield
With the case
The first circuit board housed in the case and
A second circuit board for the backlight, which is housed in the case and electrically connected to the first circuit board.
The light source provided on the second circuit board and
A temperature sensor for a light source provided on the second circuit board and
Including the processing device mounted on the first circuit board.
The processing device controls the light source based on the relationship between the temperature information from the temperature sensor for the light source and the reference temperature information representing the temperature of a portion different from the second circuit board in the case. Display device for. Further including a temperature sensor for a reference temperature provided on the first circuit board,
The vehicle display device according to claim 1, wherein the processing device acquires temperature information from the temperature sensor for the reference temperature as the reference temperature information. The processing device outputs the output of the light source when the value obtained by subtracting the reference temperature information from the temperature information from the temperature sensor for the light source exceeds the threshold value in the driving state in which the light source is driven. The vehicle display device according to claim 1, which is stopped or lowered. The vehicle display device according to claim 3, wherein the processing device changes the threshold value in such a manner that the threshold value increases as the power consumption of the light source increases.

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