WO2020105427A1

WO2020105427A1 - Vehicular display device

Info

Publication number: WO2020105427A1
Application number: PCT/JP2019/043395
Authority: WO
Inventors: 亮山岡
Original assignee: 株式会社デンソー
Priority date: 2018-11-21
Filing date: 2019-11-06
Publication date: 2020-05-28
Also published as: JP2020086070A; JP7081458B2

Abstract

This vehicular display device comprises a liquid crystal panel (15), a backlight (16), and a current control unit (222) that controls the brightness of the backlight by controlling the current flowing through the backlight. The current control unit limits the current flowing through the backlight to a greater extent when the ambient temperature of the backlight is higher than the current limiting starting temperature, than when the ambient temperature of the backlight is at or below the current limiting starting temperature, where the current limiting starting temperature is the lowest temperature at which current is reduced to reduce the amount of heat generated.

Description

Vehicle display

Cross-reference of related applications

This application is based on Japanese Patent Application No. 2018-218570 filed on November 21, 2018, and the contents of the description are incorporated herein.

The present disclosure relates to a vehicle display device that improves visibility.

A technology is known that prevents a decrease in brightness of a display device mounted on a vehicle while preventing a failure due to high temperature. In Patent Document 1, a backlight that can illuminate the liquid crystal panel for each area is provided, and the illuminated area is an area corresponding to a display image.

In Patent Document 1, since the illuminated area is limited to the area corresponding to the display image, it is possible to reduce the heat generation amount of the backlight as compared with the case of illuminating the entire area. Since the calorific value is reduced in this manner, the necessity of lowering the current to reduce the calorific value is reduced. Since the brightness is determined by the current, it is possible to suppress the decrease in the brightness by reducing the need for reducing the current, and the visibility is improved by suppressing the decrease in the brightness.

Japanese Patent Laid-Open No. 2018-106193

Even if the technique of Patent Document 1 is applied, the temperature of the device may rise to around the upper limit that guarantees the operation of the parts in the device, depending on the environment of the vehicle. Even when the technique of Patent Document 1 is applied, when the temperature of the device rises, it is necessary to reduce the current in order to reduce the heat generation amount. Hereinafter, the minimum value of the temperature at which the current is reduced will be referred to as the power supply restriction start temperature.

▽ How many times the current limit start temperature is set depends on the balance between the amount of heat generated and the amount of heat released per hour. Therefore, with the same heat dissipation structure, the smaller the amount of heat generation per unit time, the higher the current limiting start temperature can be.

The technique of Patent Document 1 limits an illuminated area to an area corresponding to a display image. However, where on the screen the display image is displayed changes depending on various situations, and the entire display screen is displayed as an image. This is the area that may be displayed. Therefore, even if the technique of Patent Document 1 is applied, it is necessary to determine the current limit start temperature on the assumption that the illuminated area is the area corresponding to the entire display screen. That is, even if the technique of Patent Document 1 is applied, the current limit start temperature cannot be increased compared to the case where the illuminated area is the entire area of the display screen regardless of the display image.

Since the current limit start temperature cannot be increased, when the temperature of the vehicle is likely to rise in a hot environment, it is easy to reach the current limit start temperature even if the backlight generates less heat. Therefore, the conventional technology needs to be improved from the viewpoint of improving visibility.

The present disclosure aims to provide a vehicle display device capable of improving visibility.

A vehicle display device according to an aspect of the present disclosure includes a liquid crystal panel, a backlight, and a current control unit that controls the brightness of the backlight by controlling the current flowing in the backlight. A predetermined part of the total display area is set as a partial display area where an image is displayed while the vehicle is running normally, while a display area wider than the partial display area is stopped by the vehicle. And that the image to be displayed is an image that reports an abnormality, at least one of which is set as a wide display area in which the image is displayed, and the backlight is a partial display area. It is possible at least for the state in which the portion corresponding to (1) can be turned on and the state in which the portion corresponding to the wide display area can be turned on. When the ambient temperature of the backlight is higher than the current limit start temperature, which is the minimum value of the temperature at which the current is reduced to reduce the amount of heat generation, the current control unit supplies the current to the backlight with the ambient temperature of the backlight. When the temperature is limited to a current flowing in the backlight at a temperature equal to or lower than the current limit start temperature and the portion corresponding to the wide display area in the backlight can be turned on, the backlight corresponds to the partial display area. In the case where the portion can be turned on, the current flowing through the portion corresponding to the wide display area in the backlight is reduced so that the heat generation amount becomes as follows.

In this vehicle display device, when the portion of the backlight corresponding to the wide display area can be turned on, the heat generation amount when the portion of the backlight corresponding to the partial display area can be turned on is equal to or less than the heat generation amount. , The current flowing in the portion corresponding to the wide display area is reduced.

With this, the current limit start temperature may be set in consideration of the case where a part corresponding to the partial display area in the backlight can be turned on. Therefore, the current limit start temperature can be made higher than in the case where the state where all the backlights are turned on is considered. As a result, high brightness can be achieved in a wide temperature range. Therefore, the visibility when the area where the image is displayed is the partial display area is improved in a wide temperature range.

However, when using a large display area, the brightness will decrease. However, when the wide display area is set, one of the conditions is satisfied, that is, the vehicle is stopped or the displayed image is an image for notifying an abnormality. If the vehicle is stopped, the driver can gaze at the display area. Since the visibility is improved from the point of view, the reduction in visibility is suppressed even if the brightness is reduced. Further, the image for notifying the abnormality is generally an image that can be seen at a glance. That is, the image that notifies the abnormality is generally an image with good visibility. Therefore, even if the brightness is reduced, the reduction in visibility is suppressed. For these reasons, it is possible to suppress a reduction in visibility when the area where the image is displayed is a wide display area.

The above and other objects, features and advantages of the present disclosure will become more apparent by the following detailed description with reference to the accompanying drawings.
It is a schematic diagram which shows the mounting state in the vehicle of the HUD apparatus in embodiment. It is a figure which shows the backlight provided with a some light emitting element. It is a figure which shows that the display area of a liquid crystal panel is divided into a plurality of small display areas. It is a block diagram which shows the function with which a control part is equipped. It is a figure which illustrated the virtual image displayed on the projection part. It is a figure which shows the duty ratio determination lines L1 and L2 which a current control part uses. It is a flow chart which shows the processing which a control part performs. It is a flow chart which shows the processing which a current control part performs.

Embodiments will be described below with reference to the drawings. FIG. 1 shows the configuration of a head-up display (HUD) device 10 which is a vehicle display device. The HUD device 10 is mounted on the vehicle 1. The HUD device 10 projects an image for virtual image toward the projection unit 3 a set on the windshield 3 of the vehicle 1. As a result, the HUD device 10 displays the virtual image so that the occupant of the vehicle 1 can visually recognize the virtual image. That is, the display light of the virtual image reflected by the projection unit 3a reaches the eye point EP of the occupant seated in the driver's seat 4 inside the vehicle 1, and the occupant perceives the display light as the virtual image VRI. In the following, front, rear, front-rear direction, upward, downward, up-down direction, left, right, and left-right directions mean directions when the vehicle 1 is on the horizontal plane HP.

The windshield 3 of the vehicle 1 is made of, for example, glass or synthetic resin in a translucent plate shape, and is arranged above the instrument panel 2. The windshield 3 forms a projection portion 3a on which display light is projected in a smooth concave shape or a flat shape. The projection unit 3a does not have to be provided on the windshield 3. For example, a combiner may be installed in the vehicle 1 and the combiner may be provided with the projection unit 3a.

The HUD device 10 is installed in the instrument panel 2, and includes a housing 11, an image display unit 14, a light guide unit 18, a control unit 22, and the like.

The housing 11 has a hollow shape that houses other elements of the HUD device 10. The housing 11 has a window 11a at the upper end. The window 11a is located in the opening provided in the upper surface of the instrument panel 2 and faces the projection unit 3a. The window portion 11a is covered with a dustproof cover 12 that can transmit display light.

The image display unit 14 is formed by housing the liquid crystal panel 15 and the backlight 16 in a case 14a. The image display unit 14 displays the virtual image on the display screen of the liquid crystal panel 15 by transmitting and illuminating the liquid crystal panel 15 by the backlight 16, and displays the display light that contributes to the display of the virtual image on the optical path. Eject toward the side.

The liquid crystal panel 15 of the present embodiment is a liquid crystal panel using thin film transistors (TFTs), and is an active matrix type liquid crystal panel formed of a plurality of liquid crystal pixels arranged in a two-dimensional direction. The liquid crystal panel 15 can control the light transmittance of each liquid crystal pixel by the incidence of light from the backlight 16, and the display light emitted from the liquid crystal panel 15 can form a virtual image. .. Adjacent liquid crystal pixels are provided with color filters of different colors (for example, red, green, and blue), and various colors are realized by combining these.

As shown in FIG. 2, the backlight 16 has a plurality of light emitting elements 16a arranged at regular intervals in a grid pattern in the x and y directions orthogonal to each other. Each of these light emitting elements 16a is, for example, a light emitting diode. Each light emitting element 16a can be turned on and off separately. The brightness of the light emitting element 16a changes according to the flowing current.

Since each light emitting element 16a can be turned on and off separately, the liquid crystal panel 15 is formed with a number of small display areas 15a corresponding to the light emitting elements 16a, as shown in FIG. The position and the number of the small display areas 15a in which the image is displayed changes according to the position and the number of the light emitting elements 16a that are turned on. The brightness of each small display area 15a changes according to the current flowing through the light emitting element 16a corresponding to each small display area 15a. The number of light emitting elements 16a shown in FIG. 2 is conceptual, and the actual number of light emitting elements 16a may be larger or smaller than the number shown in FIG.

The light guide unit 18 guides the display light incident from the image display unit 14 to the projection unit 3a. The light guide section 18 has, for example, a plane mirror 19 and a concave mirror 20. The plane mirror 19 is a reflecting mirror in which a reflecting surface is formed by evaporating aluminum on the surface of a base material made of synthetic resin or glass. The reflecting surface of the plane mirror 19 is formed into a smooth flat surface. The display light that has entered the plane mirror 19 from the image display unit 14 is reflected by the reflecting surface toward the concave mirror 20.

The concave mirror 20 is a reflecting mirror having a reflecting surface formed by evaporating aluminum on the surface of a base material made of synthetic resin or glass. The reflecting surface of the concave mirror 20 is formed in a smooth concave shape by being curved in a concave shape. The display light incident on the concave mirror 20 is reflected by the reflecting surface toward the projection unit 3a. The virtual image VRI is magnified by the reflection on the reflecting surface of the concave mirror 20, and the distortion of the virtual image VRI is reduced by forming the reflecting surface into a free-form surface.

The display light reflected by the reflection surface of the concave mirror 20 is emitted to the outside of the HUD device 10 by passing through the dust cover 12, and enters the projection portion 3 a of the windshield 3. When the display light reflected by the projection unit 3a reaches the user's eye, the user can visually recognize the virtual image VRI.

The temperature sensor 21 is a sensor for estimating the atmospheric temperature Ta (° C.) of the HUD device 100. The temperature sensor 21 is housed inside the case 14a in FIG. However, the temperature sensor 21 may be outside the case 14a as long as it can estimate the ambient temperature Ta of the HUD device 100. Further, when the ambient temperature Ta of the HUD device 100 can be estimated from the temperature sensor provided in the vehicle 1 for another purpose, the detected value of the temperature sensor provided in the vehicle 1 for another purpose is used. Based on this, the ambient temperature Ta of the HUD device 100 may be estimated.

The control unit 22 can be realized by a configuration including at least one processor. For example, the control unit 22 can be realized by a computer including a CPU, a ROM, a RAM, an I / O, and a bus line connecting these configurations. A program for causing a general-purpose computer to function as the control unit 22 is stored in the ROM. The CPU 22 executes the program stored in the ROM while using the temporary storage function of the RAM, so that the control unit 22 functions as the image generation unit 221 and the current control unit 222 illustrated in FIG. 4. Execution of these functions means that the method corresponding to the program is executed.

The image generator 221 generates virtual image data to be displayed on the liquid crystal panel 15, based on information input from other devices provided in the vehicle 1. For example, when the speed of the vehicle 1 is input as information, data for displaying a virtual image for indicating the speed is generated in a predetermined area of the liquid crystal panel 15. Information from other devices provided in the vehicle 1 is input to the control unit 22 via the in-vehicle LAN 5, for example.

After generating the image data for the virtual image, the image generation unit 221 outputs the data to the drive circuit 17. The drive circuit 17 is a circuit for driving the liquid crystal panel 15. When the data of the virtual image is input, the drive circuit 17 drives the liquid crystal panel 15 to display the virtual image represented by the input data on the liquid crystal panel 15. .. When the virtual image is displayed on the liquid crystal panel 15 and the light emitting element 16a corresponding to the area where the virtual image is displayed is turned on, the virtual image is displayed on the projection unit 3a.

FIG. 5 illustrates the virtual image displayed on the projection unit 3a. In FIG. 5, a speed image 23a, an engine rotation speed image 23b, a speed limit image 23c, a radar detection state image 23d, and a route guidance image 23e are shown as virtual images. The speed image 23a shows the current speed of the vehicle 1. The engine rotation speed image 23b shows the current rotation speed of the engine. The speed limit image 23c shows the speed limit of the road on which the vehicle 1 is currently traveling. The radar detection state image 23d shows whether or not the device mounted on the vehicle 1 for detecting a peripheral object by a radar having a frequency such as a millimeter wave is functioning. The route guidance image 23e is an image that guides the route of the vehicle 1. These are normal-time images 23 displayed at normal times. The normal time image 23 is displayed in the normal time display area 31.

The shape of the projection unit 3a in this embodiment is a horizontally long rectangle, and is divided into a normal time display area 31 and an abnormal time display area 32. Further, it is possible to display an image with a display area (hereinafter referred to as a full-screen display area) obtained by adding the normal time display area 31 and the abnormal time display area 32 as one display area. The full-screen display area is the entire projection unit 3a. The full-screen display area is a wider display area than the normal display area 31 which is a partial display area.

The normal time display area 31 is an area in which the normal time image 23 is displayed, and is the lower half when the projection unit 3a is divided into upper and lower parts. Therefore, the vertical center position of the normal display area 31 is lower than the vertical center position of the full-screen display area. The abnormal time display area 32 is a portion of the projection unit 3a above the normal time display area 31.

The normal image 23 is an image displayed while the vehicle 1 is traveling normally. Therefore, the normal display area 31 is a partial display area in which an image is displayed while the vehicle 1 is traveling normally. On the other hand, the abnormal time display area 32 is an area for displaying an image notifying the abnormality when various abnormalities occur in the vehicle 1.

Note that the normal-time image 23 is not limited to the example shown in FIG. 5, but other images such as an image showing the state of the vehicle 1 such as the remaining fuel amount, a visual field assistance image, etc. The various images shown can be the normal image 23.

When the normal display area 31 and the abnormal display area 32 are added to form a full-screen display area, information that is not essential for driving the vehicle 1 is displayed. Examples of images displayed in the full-screen display area include an opening screen for notifying the activation of the HUD device 100, an ending screen for notifying the end of the operation of the HUD device 100, a telephone directory, a mail, and a music player. Note that one or more of these need not be displayed during full-screen display, and another image may be displayed during full-screen display.

The current control unit 222 determines the light emitting element 16a that emits light, and also determines the value of the current that flows in the light emitting element 16a that emits light. Then, a drive circuit provided in the backlight 16 determines a duty ratio for driving the light emitting element 16a based on the determined current value, and a signal for instructing to control the current flowing through the light emitting element 16a at the determined duty ratio. Output to 16b. Upon receiving the signal, the drive circuit 16b drives the light emitting element 16a at the instructed duty ratio. Since the brightness of the light emitting element 16a changes depending on the current, the current control unit 222 controls the brightness of each light emitting element 16a included in the backlight 16.

The current control unit 222 determines the light emitting element 16a that illuminates the small display area 15a on which the image generated by the image generating unit 221 is displayed, as the light emitting element 16a that emits light. The value of the current flowing through the light emitting element 16a to emit light and the duty ratio of the current corresponding to the current value are determined based on the display mode and the ambient temperature Ta. The display modes include a constant content mode (corresponding to the partial display mode) and an entire display mode. The constant content mode (corresponding to the partial display mode) and the whole display mode are examples of the operation mode of the projection unit 3a.

The constant content mode is a mode in which an image is displayed only in the normal display area 31 and no image is displayed in the abnormal display area 32. The constant content mode is a display mode when the vehicle is traveling and there is no image to be displayed in the abnormal display area 32. The whole display mode is a display mode in which an image may be displayed in the abnormal time display area 32 in addition to the normal time display area 31. In the entire display mode, the normal time image 23 is displayed in the normal time display area 31 and the image indicating the abnormality is displayed in the abnormal time display area 32, the normal time display area 31 and the abnormal time display area 32. In some cases, the image is displayed in one full-screen display area obtained by adding

The current control unit 222 determines the current display mode based on the image generated by the image generation unit 221. Alternatively, the current display mode may be determined based on the traveling state of the vehicle 1. The current controller 222 determines the duty ratio for the light emitting element 16a from the determined display mode, the ambient temperature Ta acquired from the temperature sensor 21, and the duty ratio determination line L shown in FIG.

FIG. 6 shows a normal duty ratio determination line L1 used in the constant content mode and a full duty ratio determination line L2 used in the full display mode. At both the normal duty ratio determination line L1 and the overall duty ratio determination line L2, at temperatures higher than the current limit start temperature T1, the duty ratio decreases as the ambient temperature Ta increases. The reason for this is that when the temperature of the HUD device 100 approaches the upper limit of the guaranteed temperature, heat generation inside the device is suppressed.

The current limit start temperature T1 will be set based on experiments and the like. Since the current limit start temperature T1 depends on the heat dissipation of the HUD device 100 and the amount of heat generated from the backlight 16, if the amount of heat generated from the backlight 16 is small even with the same heat dissipation, the current limit start temperature T1. Can be higher. If the current limit start temperature T1 can be increased, the ambient temperature Ta at which the brightness of the backlight 16 decreases can be increased, so that the period during which the brightness of the backlight 16 decreases can be shortened.

FIG. 6 also shows a conventional duty ratio determination line Lr as a comparative example. The current limitation start temperature T1 of the normal duty ratio determination line L1 and the overall duty ratio determination line L2 is higher than the current limitation start temperature Tr of the conventional duty ratio determination line Lr.

In the conventional technique, it is necessary to determine the current limit start temperature Tr in a state where it is unknown where the image is displayed in the entire display area. Therefore, it is assumed that all the light emitting elements 16a are turned on. The starting temperature Tr is determined. On the other hand, in the present embodiment, the current limitation is started assuming that all the light emitting elements 16a corresponding to the normal display area 31 are all turned on and the light emitting elements 16a corresponding to the abnormal display area 32 are turned off. The temperature T1 is determined. That is, the current limit start temperature T1 is determined on the assumption that some of the light emitting elements 16a are turned off. Therefore, the current limit start temperature T1 of the normal duty ratio decision line L1 and the overall duty ratio decision line L2 can be made higher than the current limit start temperature Tr of the conventional duty ratio decision line Lr.

However, since the current limit start temperature T1 is determined on the assumption that only the light emitting elements 16a corresponding to the normal display area 31 are all turned on, if the brightness is always the same as that of the content mode in the whole display mode, There is a risk of exceeding the guaranteed temperature. Therefore, the duty ratio at the temperature equal to or lower than the current limit start temperature T1 is 100% in the normal duty ratio determination line L1, whereas it is lower in the whole duty ratio determination line L2. %.

In this embodiment, the normal display area 31 is 50% of the total display area. Therefore, since the duty ratio of the overall duty ratio determination line L2 at the current limit start temperature T1 or lower is set to 50%, the heat generation amount in the whole display mode can be made equal to or lower than the heat generation amount assumed in the constant content mode. ..

FIG. 7 shows an example of a process executed by the control unit 22 as a flowchart. The process shown in FIG. 7 starts when the ignition is turned on. As shown in FIG. 7, S2, S4, S6, and S8 are executed by the image generation unit 221 and the current control unit 222, and S1, S3, S5, S7, and S9 are executed by the current control unit 222.

At S1, it is determined whether the vehicle 1 is stopped. One or both of the shift position signal and the vehicle speed signal can be acquired via the in-vehicle LAN 5 to determine S1. If the determination result of S1 is YES, it will progress to S2. In S2, the opening mode is displayed with the display mode set to the whole display mode.

In S3, it is again determined whether the vehicle 1 is stopped. If the determination result in S3 is YES, the process proceeds to S4, and the image is displayed by setting the display mode to the whole display mode. In S5, it is determined whether the ignition switch is turned off. If the determination result of S5 is YES, it will progress to S6. In S6, the ending screen is displayed with the display mode set to the whole display mode. If the decision result in S5 is NO, the process returns to S3. Then, if the determination result in S3 is NO, the process proceeds to S7.

In S7, it is judged whether or not an abnormal display is made. When displaying an abnormality, an image is displayed in the abnormal time display area 32. Therefore, the process proceeds to S4, and the image is displayed in the whole display mode.

If the judgment result in S7 is NO, proceed to S8. When the process proceeds to S8, the vehicle 1 is traveling and no abnormality display is made. Therefore, in S8, the image is always displayed in the content mode. In S9, it is determined whether or not the brake is depressed. If the determination result is NO, the process returns to S8 and the image display in the content mode is always continued. On the other hand, if the decision result in S8 is YES, there is a possibility that the vehicle 1 is stopped, so the routine proceeds to S3.

FIG. 8 shows the processing executed by the current control unit 222 in S2, S4, S6 and S8 of FIG. At S11, the ambient temperature Ta is acquired. In S12, the light emitting element 16a to be turned on is determined based on the position of the image generated by the image generation unit 221. In S13, which of the normal duty ratio determination line L1 and the overall duty ratio determination line L2 is used is determined from the display mode at this point. Furthermore, the duty ratio instructed to the drive circuit 16b is determined from the determined duty ratio determination line L and the ambient temperature Ta determined in S11. In S14, a signal instructing to light the light emitting element 16a determined in S12 with the duty ratio determined in S13 is output to the drive circuit 16b.

In the HUD device 10 of the above-described embodiment, when the backlight 16 can light a part corresponding to the entire display area, the amount of heat generated is equal to or less than the amount of heat generated when the backlight 16 can light a part corresponding to the normal display area 31. Therefore, the duty ratio of the overall duty ratio determination line L2 at the current limit start temperature T1 or lower is set to 50%.

With this, the current limit start temperature T1 can be set in consideration of the case where only the portion of the backlight 16 corresponding to the normal display area 31 is turned on. Therefore, as shown in FIG. 6, the current limit start temperature T1 can be made higher than the current limit start temperature Tr of the conventional duty ratio determination line Lr. As a result, high brightness can be achieved in a wide temperature range, and visibility in the constant content mode is improved in a wide temperature range.

Note that the brightness is lower in the full display mode than in the constant content mode. However, when the whole display mode is set, the vehicle is either stopped or an abnormality is displayed. If the vehicle is stopped, the driver can gaze at the display area. Since the visibility is improved from the point of view, the reduction in visibility is suppressed even if the brightness is reduced. In addition, the image that notifies the abnormality is an image with good visibility. Therefore, even if the brightness of the image for notifying the abnormality is reduced, the reduction in visibility is suppressed. For these reasons, it is possible to suppress a decrease in visibility in the whole display mode.

Although the embodiments have been described above, the disclosed technology is not limited to the above-described embodiments, the following modifications are also included in the disclosed range, and further within the scope other than the following without departing from the gist. Various modifications can be implemented. In the following description, elements having the same reference numerals as those used up to now are the same as the elements having the same reference numerals in the previous embodiments, unless otherwise specified. Further, when only a part of the configuration is described, the above-described embodiments can be applied to other parts of the configuration.

<Modification 1>
In the embodiment, the HUD device 10 is shown as an example of the vehicle display device. The HUD device 10 has a feature that sunlight enters through the window 11a, and the projection unit 3a overlaps with the scenery of the outside world, so that high brightness is required. For these reasons, the HUD device 10 needs to be capable of maintaining high brightness at a high temperature as in the above-described embodiment. However, the vehicle display device is not limited to the HUD device 10. For example, the technology disclosed in the embodiments can be applied to a display device installed on an instrument panel.

<Modification 2>
In the embodiment, the whole display mode is set when the vehicle 1 is stopped. However, the present invention is not limited to this, and when the vehicle 1 is stopped and the display mode is switched from the constant content mode to the general display mode, the user operates the changeover switch to operate the constant content mode. May be switched to the whole display mode.

<Modification 3>
In the embodiment, when displaying an abnormality, the image is displayed in the abnormal display area 32 while the normal image 23 is displayed in the normal display area 31. However, when the abnormality is displayed, an image notifying the abnormality may be displayed in the full-screen display area as the full-screen display area.

Further, when displaying an abnormality, the image displayed in the normal display area 31 is erased, the light emitting element 16a corresponding to the normal display area 31 is turned off, and the abnormal display area 32 is notified of the abnormality. The image may be displayed. In this case, the current flowing through the light emitting element 16a corresponding to the abnormal time display area 32 can always be determined using the duty ratio determination line L1. Therefore, the brightness of the image displayed in the abnormal time display area 32 can be made higher than that in the embodiment.

<Modification 4>
In the embodiment, only the light emitting element 16a corresponding to the small display area 15a including the image displayed on the liquid crystal panel 15 is turned on. However, all the light emitting elements 16a corresponding to the entire display area determined by the display mode may be turned on.

<Modification 5>
In the embodiment, the normal display area 31 is 50% of the entire display area. However, the area ratio of the normal display area 31 to the entire display area does not need to be 50%, and may be smaller than 50% or conversely larger than 50%. Further, the entire display area does not have to be the entire projection unit 3a.

<Modification 6>
The method executed by the control unit 22 described in the present disclosure may be realized by a dedicated computer that configures a processor programmed to execute one or a plurality of functions embodied by a computer program. Alternatively, the control unit and its method described in the present disclosure may be realized by a dedicated hardware logic circuit. Alternatively, the control unit and the method thereof described in the present disclosure may be implemented by one or more dedicated computers configured by a combination of a processor that executes a computer program and one or more hardware logic circuits. The hardware logic circuit is, for example, an ASIC or FPGA.

Moreover, the storage medium for storing the computer program is not limited to the ROM, and may be any computer-readable non-transitional tangible recording medium as the instruction executed by the computer. For example, the above program may be stored in a flash memory.

Here, the flowchart described in this application or the process of the flowchart is composed of a plurality of sections (or referred to as steps), and each section is expressed as, for example, S1. Further, each section can be divided into multiple subsections, while multiple sections can be combined into one section. Further, each section thus configured can be referred to as a device, module, means.

Claims

A liquid crystal panel (15),
A backlight (16),
A vehicle display device comprising: a current control unit (222) for controlling the brightness of the backlight by controlling a current passed through the backlight,
A predetermined partial area of the entire display area is set as a partial display area (31) in which an image is displayed while the vehicle is normally traveling, while the display area wider than the partial display area is set. A wide display area (3a) where an image is displayed under at least one of the condition that the vehicle is stopped and the image that is displayed is an image that reports an abnormality. Cage,
The backlight is at least capable of lighting a portion corresponding to the partial display area and capable of lighting a portion corresponding to the wide display area,
The current control unit, when the ambient temperature of the backlight is higher than the current limit start temperature, which is the lowest value of the temperature at which the current is reduced in order to reduce the amount of heat generation, the current supplied to the backlight is In the case where the ambient temperature of the backlight is limited to a current flowing in the backlight at a temperature equal to or lower than the current limit start temperature, and the portion of the backlight corresponding to the wide display area can be turned on, A display device for a vehicle, in which a current flowing through a portion of the backlight corresponding to the wide display area is reduced so that a heat generation amount is as follows when a portion of the backlight corresponding to the partial display area can be turned on.
The vehicle display device according to claim 1, which is a head-up display device.
The vehicle display device according to claim 2, wherein a vertical center position of the partial display area is lower than a vertical center position of the display area.
The current control unit, the vehicle is stopped, and based on that the changeover switch operated by the user when switching the area for displaying an image from the partial display area to the wide display area is operated, The vehicle display device according to any one of claims 1 to 3, wherein a portion of the backlight corresponding to the wide display area can be turned on.
4. The current control unit enables lighting of a portion of the backlight corresponding to the wide display area based on the determination that the vehicle has stopped. The vehicle display device described.
A liquid crystal panel (15),
A backlight (16),
A projection unit (3a) for displaying a virtual image by projecting a virtual image from the liquid crystal panel;
A current control unit (222) for controlling a current flowing through the backlight,
The projection unit is set to an operation mode of either a full display mode or a partial display mode,
In the entire display mode, the virtual image is displayed in the entire display area of the projection unit,
In the partial display mode, the virtual image is displayed in a predetermined partial display area of all the display areas,
When the vehicle is stopped, and if the virtual image satisfies any condition of notifying an abnormality, the projection unit is set to the whole display mode,
When the vehicle is traveling normally, the projection unit is set to the partial display mode,
When the projection unit is set to the entire display mode, the backlight is capable of lighting a portion corresponding to the entire display area,
When the projection unit is set to the partial display mode, the backlight can light the part corresponding to the partial display area. The current limit start temperature is for reducing the heat generation amount of the backlight. Is the minimum value of the temperature that reduces the current,
The current control unit, when the ambient temperature of the backlight is higher than the current limit start temperature, supplies a current to the backlight at a temperature where the ambient temperature of the backlight is equal to or lower than the current limit start temperature. Limit the current to the backlight,
When the projection unit is set to the whole display mode, the current control unit sets the following heat generation amount when the projection unit is set to the partial display mode, in the backlight. A vehicular display device for reducing a current flowing through a portion corresponding to the entire display area.