Head-up display device

Abstract

A head-up display device is provided that can determine an abnormality in a light source with a simple configuration while performing local dimming control. [Solution] The head-up display device includes a display 13 having a display surface for displaying an image, a plurality of light sources 40 for illuminating the display 13, a plurality of drivers 21a-21n for driving the plurality of light sources 40, a control unit 50 for controlling the display of images and the lighting of the light sources 40, and a current detection circuit 60 for detecting a total current value Iw of current values ​​I1-In supplied from the drivers 21a-21n to the plurality of light sources 40. In the lighting control, the control unit 50 performs local dimming control for adjusting the brightness of each of a plurality of display regions divided into the display surface, and determines that an abnormality has occurred when the total current value Iw detected by the current detection circuit 60 exceeds a current threshold Th. The current threshold Th is increased or decreased in accordance with an increase or decrease in the brightness of the display of the entire image.

Description

[Technical Field]

[0001] The present disclosure relates to a head-up display device. [Background technology]

[0002] The head-up display device described in Patent Document 1 includes a light source, a display panel that receives light from the light source and emits display light, a microcomputer that controls the light source and the display panel, and a light source driver that turns on the light source by amplifying a PWM signal from the microcomputer and outputting it to the light source, and this light source driver receives the cathode voltage of the light source and determines whether the light source has failed.

[0003] The head-up display device described in Patent Document 2 is configured to perform so-called local dimming control, in which LEDs (Light Emitting Diodes) belonging to a light-emitting area are turned on while LEDs not belonging to the light-emitting area are not turned on, depending on the displayed image. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] International Publication No. 2020 / 235683 [Patent Document 2] Patent Publication No. 2021-110816 Summary of the Invention [Problem to be solved by the invention]

[0005] In the configuration for performing local dimming control described in Patent Document 2, it is common for multiple LEDs to be connected in series for each dimming zone, and for these LEDs to be connected in parallel. In such a configuration, in order to determine a fault in the light source described in Patent Document 1, it is necessary to provide a means for detecting the light source current for each light source row, which makes the configuration complicated.

[0006] The present disclosure has been made in consideration of the above-described circumstances, and aims to provide a head-up display device that can perform local dimming control while determining abnormalities in a light source with a simple configuration. [Means for solving the problem]

[0007] In order to achieve the above object, a head-up display device according to the present disclosure includes: a display having a display surface for displaying an image; a plurality of light sources for illuminating the indicator; a plurality of drivers for driving the plurality of light sources, respectively; a control unit that controls display of the image on the display surface and controls lighting of the plurality of light sources via the plurality of drivers; a current detection unit that detects a total current value of currents supplied from the plurality of drivers to the plurality of light sources, The control unit In the lighting control of the plurality of light sources, local dimming control is performed to adjust brightness for each of a plurality of display regions obtained by dividing the display surface, determining that an abnormality has occurred when the total current value detected by the current detection unit exceeds a current threshold value; The current threshold is increased or decreased in accordance with an increase or decrease in brightness of the display of the entire image on the display surface. [Effects of the Invention]

[0008] According to the present disclosure, it is possible to determine an abnormality in a light source with a simple configuration while performing local dimming control. [Brief explanation of the drawings]

[0009] [Figure 1] 1 is a schematic diagram of a vehicle equipped with a head-up display device according to an embodiment of the present disclosure. [Figure 2] FIG. 2 is a schematic diagram of a display surface according to an embodiment of the present disclosure. [Figure 3] 1 is a block diagram of a display device according to an embodiment of the present disclosure. [Figure 4]10 is a flowchart of a light source abnormality determination process according to an embodiment of the present disclosure. DETAILED DESCRIPTION OF THE INVENTION

[0010] A head-up display device according to an embodiment of the present disclosure will be described with reference to the drawings. 1, the head-up display device 100 is installed, for example, in the dashboard of a vehicle 200. The head-up display device 100 emits display light L representing an image toward a windshield 201 of the vehicle 200, and guides the display light L reflected by the windshield 201 to an eye box Eb. When the viewpoint of a viewer 1 (mainly the driver) is positioned within the eye box Eb, a virtual image V corresponding to the display light L becomes visible to the viewer 1.

[0011] The head-up display device 100 includes a display device 10, a folding mirror 31, a concave mirror 32, a housing 33, and a control unit 50.

[0012] The housing 33 is formed in a box shape from light-blocking resin or metal, and houses the display device 10, the folding mirror 31, and the concave mirror 32. An opening is formed in the housing 33 at a position facing the windshield 201 in the height direction, and a window 33a made of a light-transmitting resin such as acrylic is fitted into this opening.

[0013] The folding mirror 31 reflects the display light L from the display device 10 toward the concave mirror 32. The folding mirror 31 is a plane mirror, a free-form surface mirror, a convex mirror, or a concave mirror. The concave mirror 32 reflects the display light L from the folding mirror 31 toward the windshield 201.

[0014] The control unit 50 includes a CPU (Central Processing Unit), a GDC (Graphics Display Controller), a ROM (Read Only Memory), and a RAM (Random Access Memory). The control unit 50 controls the display device 10 (for example, the plurality of light sources 40 and the display 13). The control unit 50 may be configured with the CPU and GDC as separate units, or may be configured with the CPU and GDC as an integrated unit. The lighting control of the light source 40 by the control unit 50 will be described later.

[0015] The display device 10 emits display light L. The display device 10 includes a display 13, a plurality of light sources 40 that illuminate the display 13, and a light source substrate 45 on which the plurality of light sources 40 are mounted. The plurality of light sources 40 are each made up of an LED, and are arranged in a matrix on the mounting surface of the light source board 45 on the display 13 side.

[0016] The display 13 is a TFT (Thin Film Transistor) liquid crystal panel. The display 13 has a display surface 13a that displays an image Ig. The display 13 receives illumination light from a plurality of light sources 40 and emits display light L while displaying the image Ig on the display surface 13a. 2, the display surface 13a has a rectangular shape that is long in the left-right direction and short in the up-down direction. Here, the left-right direction and the up-down direction of the display surface 13a correspond to the left-right direction and the up-down direction as seen by the viewer 1 viewing the virtual image V.

[0017] The display surface 13a and the image Ig are divided into a plurality of display areas AR1 to AR4 (dimming zones), and different types of display content (images Ig) are displayed in each of the display areas AR1 to AR4. Display area AR1 is formed across the entire lower portion of display surface 13a in the horizontal direction. Display area AR2 is located above display area AR1, in the horizontal center of display surface 13a. Display areas AR3 and AR4 are located on both sides of display area AR2 in the horizontal direction. Display area AR1 displays vehicle information such as vehicle speed. Display area AR2 displays route guidance information from a car navigation system. Display area AR4 displays sign information. Display area AR2 includes information that must always be displayed, such as vehicle speed, and also includes information that is displayed at necessary times, such as guidance for turning right or left, and is hidden once this necessary time has passed.

[0018] Next, the circuit configuration of the display device 10 will be described with reference to FIG. The display device 10 includes a plurality of light sources 40, a display 13, a plurality of drivers 21a, 21b, . . . , 21n (n is an arbitrary natural number), and a single current detection circuit 60.

[0019] The plurality of light sources 40 (LEDs) are configured such that a plurality of LEDs are connected in series, and the series-connected LEDs are connected in parallel in a plurality of columns C1 to Cn (n is any natural number). Drivers 21a, 21b...21n are provided in one-to-one correspondence with each of columns C1 to Cn. Driver 21a is connected to the plurality of light sources 40 in column C1 and drives the plurality of light sources 40 in column C1 to light up. Driver 21b is connected to the plurality of light sources 40 in column C2 and drives the plurality of light sources 40 in column C2 to light up. Driver 21n is connected to the plurality of light sources 40 in column Cn and drives the plurality of light sources 40 in column Cn to light up.

[0020] Each column C1 to Cn of light sources 40 corresponds to a display region AR1 to AR4 (see FIG. 2). For example, the light sources 40 in column C1 light up the display region AR1, the light sources 40 in column C2 light up the display region AR2, and similarly, the light sources 40 in each of the other two columns light up the display regions AR3 and AR4. The drivers 21a to 21n drive the light sources 40 in the corresponding columns C1 to Cn. Specifically, the drivers 21a to 21n receive PWM control signals from the control unit 50 and supply PWM drive signals corresponding to the PWM control signals to the light sources 40 in the corresponding columns C1 to Cn. The light sources 40 in each column C1 to Cn light up at a brightness corresponding to the duty ratio of the PWM drive signal.

[0021] The current detection circuit 60 is provided on a power line LV between the battery BAT and each of the drivers 21a to 21n. The power line LV extends from the battery BAT, branches at a branch point P along the way, and is connected to each of the drivers 21a to 21n. The current detection circuit 60 is provided on one of the power lines LV closer to the battery BAT than the branch point P. The current detection circuit 60 detects a total current value Iw of current values ​​I1 to In (n is an arbitrary natural number) supplied from the multiple drivers 21a to 21n to the light sources 40 in each of the columns C1 to Cn. The total current value Iw is made up of "I1 + I2 +... + In." The current detection circuit 60 outputs this detection result to the control unit 50 as a detection signal Sd.

[0022] Next, the lighting control of the light source 40 by the control unit 50 will be described. The control unit 50 performs local dimming control to adjust the brightness of each of the plurality of light sources 40 for each of the plurality of display areas AR1 to AR4 as lighting control for the light sources 40. To achieve this brightness adjustment for each of the display areas AR1 to AR4, the control unit 50 adjusts the duty ratio of the PWM drive signals output to each of the drivers 21a to 21n.

[0023] Next, the light source abnormality determination process performed by the control unit 50 will be described with reference to the flowchart of FIG. The control unit 50 receives the detection signal Sd from the current detection circuit 60 and acquires the total current value Iw based on the received detection signal Sd (step S101).

[0024] The control unit 50 also determines the current threshold Th based on the average brightness of the display of the entire image Ig on the display surface 13a (step S102). This display brightness is specified, for example, by the average RGB value of the entire image Ig on the display surface 13a. The current threshold Th is set to increase as the average brightness of the display of the entire image Ig increases, and to decrease as the brightness of the display of the entire image Ig decreases. For example, when a route guidance arrow icon is displayed in the display area AR2 and then the arrow icon disappears, the average brightness of the display of the entire image Ig decreases, and the current threshold Th decreases. It should be noted that the average brightness of this display is not limited to RGB, and may be specified based on HSV. The current threshold Th is set to be larger than the total current value Iw when the average brightness of the display of the entire image Ig is at its maximum in the display mode of the image Ig in actual use, and smaller than the total current value Iw when an overcurrent occurs in any one of the light sources 40 of the columns C1 to Cn. In step S102, the control unit 50 may determine the current threshold value Th from the brightness of the display by referring to a data table, or may determine the current threshold value Th from the brightness of the display by using a calculation formula.

[0025] The control unit 50 determines whether the acquired total current value Iw exceeds the current threshold value Th (step S103), and if it determines that the total current value Iw exceeds the current threshold value Th (step S103; YES), it determines that an overcurrent has occurred and that there is an abnormality in the light source, and performs protection processing to protect the display device 10 from the overcurrent (step S104), and ends the light source abnormality determination processing. This protection processing may include stopping the supply of current to all light sources 40, or reducing the value of the current supplied to the light sources 40. On the other hand, if it is determined that the total current value Iw is less than the current threshold value Th (step S103; NO), the light source abnormality determination process is terminated without performing the process of step S104.

[0026] (effect) According to the embodiment described above, the following effects are achieved. (1) A head-up display device 100 includes a display 13 having a display surface 13a that displays an image Ig, a plurality of light sources 40 that illuminate the display 13, a plurality of drivers 21a-21n that respectively drive the light sources 40, a control unit 50 that controls the display of the image Ig on the display surface 13a and the lighting of the plurality of light sources 40 via the plurality of drivers 21a-21n, and a current detection circuit 60 that is an example of a current detection unit that detects a total current value Iw of current values ​​I1-In supplied from the plurality of drivers 21a-21n to the plurality of light sources 40. In controlling the lighting of the plurality of light sources 40, the control unit 50 performs local dimming control that adjusts the brightness of each of a plurality of display areas AR1-AR4 that are partitions of the display surface 13a, and determines that an abnormality has occurred when the total current value Iw detected by the current detection circuit 60 exceeds a current threshold Th. The current threshold Th is increased or decreased according to an increase or decrease in the brightness of the entire display of the image Ig on the display surface 13a. According to this configuration, the current detection circuits 60 detect the total current value Iw, which reduces the number of current detection circuits 60. Therefore, it is possible to perform abnormality determination of the light source 40 with a simple configuration while performing local dimming control.

[0027] (2) The multiple drivers 21a to 21n correspond one-to-one to the multiple display areas AR1 to AR4. Each of the multiple drivers 21a to 21n supplies current to the series-connected light sources 40 to light up the corresponding display area AR1 to AR4. Different types of display content are displayed in the multiple display areas AR1 to AR4. With this configuration, different types of display content are displayed in each of the display areas AR1 to AR4, and the brightness of each of the display areas AR1 to AR4 can be adjusted. Even in this case, the current detection circuit 60 detects the total current value Iw, so that the number of current detection circuits 60 can be reduced, and the configuration can be simplified.

[0028] The present disclosure is not limited to the above-described embodiments and drawings. Modifications (including deletion of components) may be made as appropriate within the scope of the present disclosure. An example of such a modification is described below.

[0029] (Variation) In the above embodiment, the display 13 is a liquid crystal panel, but this is not limited to this and may be a laser light scanning system using MEMS (Micro Electro Mechanical Systems) or a system using DMD (Digital Micro mirror Device).

[0030] In the above embodiment, the head-up display device 100 is mounted on the vehicle 200, but it may be mounted on other vehicles such as an airplane, a ship, etc. The projection member onto which the display light L is projected is not limited to the windshield 201, but may be a dedicated combiner. In the above embodiment, the display device 10 is applied to the head-up display device 100, but is not limited to this and may be a direct-view display device. The number and shape of the plurality of display areas AR1 to AR4 can be changed as appropriate. In the above embodiment, different types of display content are displayed in each of the display areas AR1 to AR4, but the display areas AR1 to AR4 may be formed in a rectangular shape that partitions the display surface 13a regardless of the display content. In the above embodiment, the display device 10 includes a single current detection circuit 60, but may include multiple current detection circuits 60. For example, the first current detection circuit may detect the total current value of the currents from the first and second drivers to the light source 40, and the second current detection circuit may detect the total current value of the currents from the third and fourth drivers to the light source 40. Even in this case, the number of current detection circuits can be fewer than the number of drivers. [Explanation of symbols]

[0031] 1...Viewer 10... display device, 13... display unit, 13a... display surface, 21a to 21n... drivers, 40... light source, 45... light source board 31...folding mirror, 32...concave mirror 33...housing, 33a...window portion 50...Control unit 60...Current detection circuit 100...Head-up display device 200...Vehicle, 201...Windshield C1 to Cn: column, L: display light, P: branch point, V: virtual image, AR1 to AR4: display area, BAT: battery, Eb: eye box, LV: power line, Ig: image, Sd: detection signal, Th: current threshold, I1 to In: current value, Iw: total current value

Claims

1. a display having a display surface for displaying an image; a plurality of light sources for illuminating the indicator; a plurality of drivers for driving the plurality of light sources, respectively; a control unit that controls display of the image on the display surface and controls lighting of the plurality of light sources via the plurality of drivers; a current detection unit that detects a total current value of currents supplied from the plurality of drivers to the plurality of light sources, The control unit In the lighting control of the plurality of light sources, local dimming control is performed to adjust brightness for each of a plurality of display regions obtained by dividing the display surface, determining that an abnormality has occurred when the total current value detected by the current detection unit exceeds a current threshold value; the current threshold is increased or decreased in accordance with an increase or decrease in brightness of the display of the entire image on the display surface; Head-up display device.

2. the plurality of drivers correspond one-to-one to the plurality of display areas, each of the plurality of drivers supplies a current to the light sources connected in series to light up the corresponding display area; The plurality of display areas each display a different type of display content. The head-up display device according to claim 1 .

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