Vehicular display device

Abstract

To provide a vehicular display device that can properly turn off a power supply circuit when an abnormality occurs on a control circuit to prevent power supply from being wastefully consumed.SOLUTION: The vehicular display device is provided with: a display tool 2; a power supply circuit 3 that performs power supply to the display tool 2; a control circuit 1 that controls the display tool 2 and the power supply circuit 3 on the basis of external input; a watch-dog circuit 4 that determines whether the control circuit 1 is normally operated or not; and a selecting circuit 5 that turns off the power supply circuit 3, when a first off signal from the control circuit 1 or a second off signal from the watch-dog circuit 4 is inputted.SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] The present disclosure relates to a display device for a vehicle. [Background technology]

[0002] 2. Description of the Related Art There is known a vehicle display device that displays an image including vehicle information by controlling a display device (eg, a liquid crystal display) with a control circuit (eg, a microcomputer) (see, for example, Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2012-30703 A Summary of the Invention [Problem to be solved by the invention]

[0004] However, in this type of vehicle display device, even if the display unit is unable to display due to an abnormality in the control circuit, power may continue to be supplied to the display unit, resulting in unnecessary power consumption.

[0005] Therefore, an object of the present disclosure is to provide a vehicle display device that can appropriately turn off a power supply circuit when an abnormality occurs in a control circuit, thereby preventing unnecessary power consumption. [Means for solving the problem]

[0006] On one side, A display device; a power supply circuit for supplying power to the display; A control circuit for controlling the display device and the power supply circuit based on an external input; a watchdog circuit for determining whether the control circuit is operating normally; and a selection circuit that turns off the power supply circuit when a first off signal from the control circuit or a second off signal from the watchdog circuit is input. Effect of the Invention

[0007] According to the present disclosure, when an abnormality occurs in a control circuit, the power supply circuit can be appropriately turned off, thereby preventing unnecessary power consumption. [Brief description of the drawings]

[0008] [Figure 1] 1 is a diagram showing a configuration of a vehicle display device according to an embodiment; [Diagram 2] 1 is a diagram showing a configuration of a power supply control circuit of a display device for a vehicle according to an embodiment of the present invention; [Diagram 3] FIG. 13 is a diagram showing transitions during normal startup. [Figure 4] FIG. 13 is a diagram showing a transition during an abnormality. [Diagram 5] FIG. 13 is a diagram showing a transition during normal off state. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009] 1 is an instrument that displays vehicle information to a vehicle occupant. The vehicle display device M is mounted on an instrument panel of the vehicle.

[0010] Vehicle information is information related to driving the vehicle, such as the vehicle's driving speed, engine RPM, vehicle automatic control status, warning lights, remaining fuel amount (remaining energy amount), tire pressure, route guidance information, and footage from an onboard camera.

[0011] The automatic vehicle control state is an operating state of an automatic driving mode in which the vehicle automatically controls the acceleration / deceleration and steering of the vehicle. The automatic driving mode includes, for example, an autopilot mode in which the vehicle travels at a constant speed while maintaining a constant distance from the vehicle ahead, an auto lane change mode in which the vehicle controls the steering and changes lanes when the driver operates the turn signal, and an auto park mode in which the vehicle moves to a location where it determines it is possible to park and parks it.

[0012] The operating state of the autopilot mode is, for example, the target driving speed, the detection state of the vehicle ahead, the distance between the vehicle ahead, the driver's driving readiness state, the autopilot mode cancellation warning, etc. The driver's driving readiness state is determined by whether or not the driver has his / her hands on the steering wheel and is ready to immediately start manual driving.

[0013] The operating status of the auto lane change mode includes, for example, the detection status of obstacles ahead of the lane change (presence or absence of a following vehicle), guidance on the vehicle's route when changing lanes, the driver's driving preparation status, and a warning prior to the cancellation of the auto lane change.

[0014] The operating status of the autopark mode includes, for example, candidate parking locations on a map (or on an image captured by an external camera), the planned parking location, images of the area around the vehicle captured by an external camera, the driver's driving preparation status, a warning prior to the cancellation of the autopark mode, etc.

[0015] As shown in FIG. 1, the vehicle display device M includes a control circuit 1 and a display device 2.

[0016] The control circuit 1 is composed of a SOC (System On a Chip) and a microcomputer (microcontroller). The SOC is an integrated semiconductor chip that implements the functions necessary for the operation of the vehicle display device M in a single integrated circuit chip. The function necessary for the operation of the vehicle display device M is the function of displaying vehicle information on the display device 2. The control circuit 1 displays on the display device 2 the vehicle information acquired from the in-vehicle control unit E via the in-vehicle network N. The control circuit 1 also acquires a video signal of the surroundings of the vehicle from an in-vehicle camera C that captures the surroundings of the vehicle, and displays the video signal on the display device 2 as necessary.

[0017] The display device 2 is a device that displays images, such as a liquid crystal display or an organic EL display. For example, a liquid crystal display includes a liquid crystal display element (liquid crystal panel) and a light source (backlight) that transmits and illuminates the liquid crystal display element. The display device 2 receives the video signal output by the control circuit 1 and displays an image based on the video signal on a screen.

[0018] The control circuit 1 includes a first processor core 11A, a second processor core 11B, a third processor core 11C, a PVT monitor unit 12, a communication unit 13, a video input unit 14, a display control unit 15, a ROM 16, a RAM 17, a 2D drawing unit 18, and a 3D drawing unit 19 built therein.

[0019] The first processor core 11A is an arithmetic unit that functions independently from the other cores.

[0020] The first processor core 11A operates by executing software for the first processor core. The software for the first processor core includes a boot loader BL2, an OS (Operating System), normal screen drawing software, update function software, image data for normal screen drawing, sound data for normal screen drawing, and the like.

[0021] The boot loader BL2 loads the software for the first processor core stored in the ROM 16 into the RAM 17, and enables the first processor core 11A to execute the software for the first processor core. The boot loader BL2 has a function of verifying the integrity of the software for the first processor core during or after loading the software for the first processor core. The verification of the integrity uses digital signature technology such as ECDSA (Elliptic Curve Digital Signature Algorithm) to check whether the software for the first processor core has been tampered with or has any other defects.

[0022] The OS is basic software for executing normal screen drawing software and update function software, and is, for example, the Linux (registered trademark) OS.

[0023] The normal screen drawing software is an application program that runs on the OS. In the normal display mode, the normal screen drawing software draws an image representing vehicle information in the RAM 17 in order to display the normal screen by 3D drawing on the display device 2.

[0024] The update function software is an application program that runs on the OS and is a program for updating the software of each of the processor cores 11A, 11B, and 11C.

[0025] The image data for drawing a normal screen and the sound data for drawing a normal screen are data used by the normal screen drawing software for drawing the normal screen.

[0026] The second processor core 11B is an arithmetic unit that functions independently from the other cores. The second processor core 11B includes an internal memory 11B1. The internal memory 11B1 includes an in-core ROM and an in-core RAM.

[0027] The second processor core 11B loads and executes second processor core software stored in the in-core ROM or ROM 16 into the in-core RAM or RAM 17. The second processor core software includes a boot loader BL1 and communication software.

[0028] Boot loader BL1 is a program stored in the internal ROM, and is started with its integrity guaranteed. When boot loader BL1 is started, it verifies the integrity of boot loader BL2 and boot loader BL3, which will be described later. Boot loader BL1 also loads communication software from ROM 16 and verifies the integrity of the communication software. The method used for these verifications is, for example, the same as that for boot loader BL2.

[0029] The communication software is a program for communicating with in-vehicle devices via the communication unit 13. The communication software acquires vehicle information, such as the vehicle's running speed and engine speed, from the in-vehicle ECU.

[0030] The third processor core 11C is an arithmetic unit that functions independently from the other cores.

[0031] The third processor core 11C operates by executing software for the third processor core, which includes a boot loader BL3, startup screen drawing software, startup screen drawing image data, and startup screen drawing sound data.

[0032] The boot loader BL3 loads the software for the third processor core stored in the ROM 16 into the RAM 17, and enables the third processor core 11C to execute the software for the third processor core. The boot loader BL3 has a function of verifying the integrity of the software for the third processor core during or after loading the software for the third processor core. This verification method is the same as, for example, the boot loader BL2.

[0033] The startup screen drawing software draws an image representing vehicle information in the RAM 17 in order to display a startup screen by 2D drawing on the display 2 in the startup display mode.

[0034] The image data for drawing the startup screen and the sound data for drawing the startup screen are This is the data used to draw the startup screen.

[0035] The PVT (Process Voltage and Temperature) monitor unit 12 is a functional block that monitors whether the operation of each of the processor cores 11A to 11C is normal. The PVT monitor unit 12 monitors whether the power supply voltage and the operating clock supplied to each of the processor cores 11A to 11C are normal. The PVT monitor unit 12 also monitors whether the temperature of each of the processor cores 11A to 11C is within an operation guarantee range.

[0036] The communication unit 13 is a functional block that performs communication in accordance with a predetermined communication protocol. The predetermined communication protocol is, for example, CAN (Controller Area Network), LIN (Local Interconnect Network), MOST (Media Oriented Systems Transport), Ethernet, etc. The communication unit 13 communicates with the in-vehicle control unit E via the in-vehicle network N to acquire vehicle information and stores it in the RAM 17.

[0037] The video input unit 14 is a functional block that inputs a video signal of a predetermined standard. The video signal of the predetermined standard is NTSC (National Television System Committee), LVDS (Low Voltage Differential Signaling), HDMI (registered trademark) (High-Definition Multimedia Interface), etc. The video input unit 14 inputs a video signal of an image of the surroundings of the vehicle from the on-board camera C, and stores the video signal in the RAM 17.

[0038] The display control unit 15 is a functional block that outputs a video signal of a predetermined standard to the display device 2 and causes the display device 2 to display an image showing vehicle information. The video signal of the predetermined standard is LVDS, HDMI (registered trademark), or the like.

[0039] The ROM 16 is, for example, a NAND type flash memory or a NOR type flash memory.

[0040] The RAM 17 is, for example, a DDR SDRAM that transfers data by a DDR (Double Data Rate) method. The RAM 17 is a work memory that temporarily stores data calculated by each of the processor cores 11A to 11C.

[0041] The 2D drawing unit 18 is a functional block that draws two-dimensional vector graphics or raster graphics images.

[0042] The 3D drawing unit 19 is a functional block that draws three-dimensional computer graphic images.

[0043] Next, a power supply control circuit of the vehicle display device M will be described with reference to FIGS.

[0044] As shown in FIG. 2, the power supply control circuit of the vehicle display device M includes the above-mentioned control circuit 1, a power supply circuit 3, a watchdog circuit 4, and a selection circuit 5.

[0045] The power supply circuit 3 supplies power to the display device 2. The power supply circuit 3 is turned on / off based on Hi / Lo of a power control signal PWR_EN2 input from the outside, and starts / stops the power supply to the display device 2.

[0046] The control circuit 1 outputs a power supply control signal PWR_EN1 that turns on / off the power supply circuit 3. For example, as shown in Fig. 3, the control circuit 1 switches the power supply control signal PWR_EN1 from Lo to Hi after a predetermined time T2 in response to an externally input ignition signal IG (or other external input signal CAN_INH, etc.) being turned on. Also, as shown in Fig. 5, the control circuit 1 switches the power supply control signal PWR_EN1 from Hi to Lo after a predetermined time T1 in response to an ignition signal IG being turned off (hereinafter, this may be referred to as a first off signal).

[0047] Furthermore, as shown in FIG. 3, the control circuit 1 periodically outputs a square wave WDI to the watchdog circuit 4 while operating normally.

[0048] The watchdog circuit 4 determines whether or not the control circuit 1 is operating normally. The watchdog circuit 4 includes a watchdog timer IC 41 and a flip-flop .

[0049] As shown in FIG. 4, the watchdog timer IC 41 is WDWhen there is no input of the rectangular wave WDI beyond this period, the control circuit 1 determines that an abnormal state exists, and outputs a reset signal RESET (for example, a falling rectangular wave) to the flip-flop 42.

[0050] As shown in FIGS. 3 to 5, the power supply of the watchdog timer IC 41 is turned on when the power supply control signal PWR_EN1 switches from Lo to Hi, and is turned off when the power supply control signal PWR_EN1 switches from Hi to Lo.

[0051] As shown in FIG. WD is set to be longer than the expected time T3 from when the control circuit 1 switches the power supply control signal PWR_EN1 from Lo to Hi to when it starts outputting the rectangular wave WDI. WD is set to be longer than the expected time T1 until the control circuit 1 switches the power supply control signal PWR_EN1 from Hi to Lo in response to the ignition signal IG being turned off. WD This setting is made by selecting the capacitance of the capacitor connected to the watchdog timer IC41.

[0052] The flip-flop 42 holds the reset signal RESET from the watchdog timer IC 41 and outputs it as a second off signal to the selection circuit 5. For example, the flip-flop 42 is a toggle flip-flop (T-FF) whose output is inverted by a falling edge input.

[0053] The selection circuit 5 receives the power supply control signal PWR_EN1 output from the control circuit 1 and the output signal of the flip-flop 42, and switches between Hi / Lo of the power supply control signal PWR_EN2 to be output to the power supply circuit 3 according to Hi / Lo of both signals. For example, the selection circuit 5 is an AND circuit, and sets the power supply control signal PWR_EN2 to Hi and turns on the power supply circuit 3 only when the power supply control signal PWR_EN1 output from the control circuit 1 is Hi and the output signal of the flip-flop 42 is Hi. In other words, the selection circuit 5 turns off the power supply circuit 3 when it receives the first off signal from the control circuit 1 or the second off signal from the flip-flop 42.

[0054] Next, the operation of the power supply control circuit of the vehicle display device M will be described with reference to FIGS.

[0055] 3, when an externally input ignition signal IG is turned on, the control circuit 1 switches the power supply control signal PWR_EN1 from Lo to Hi after a predetermined time T2. When the power supply control signal PWR_EN1 switches from Lo to Hi, the power supply of the watchdog circuit 4 is turned on, and the reset signal RESET output by the watchdog timer IC41 and the output signal of the flip-flop 42 switch from Lo to Hi. When the power supply control signal PWR_EN1 output by the control circuit 1 and the output signal of the flip-flop 42 both become Hi, the selection circuit 5 sets the power supply control signal PWR_EN2 it outputs to Hi and turns on the power supply circuit 3.

[0056] In addition, when the control circuit 1 is started normally, after switching the power supply control signal PWR_EN1 from Lo to Hi, the control circuit 1 periodically outputs a rectangular wave WDI to the watchdog timer IC 41. The watchdog timer IC 41 is turned on for a predetermined time T WD 3, if there is an input of a square wave WDI, the control circuit 1 is determined to be normal and does not output a reset signal RESET (falling square wave). WDis set to be longer than the expected time T3 from when the control circuit 1 switches the power supply control signal PWR_EN1 from Lo to Hi to when it starts outputting the rectangular wave WDI, thereby preventing erroneous abnormality determination at start-up.

[0057] On the other hand, if an abnormality occurs during startup (for example, software loading fails due to a memory abnormality), the control circuit 1 does not output the rectangular wave WDI as shown in FIG. WD Since there is no input of the square wave WDI beyond this, the control circuit 1 determines that an abnormal state has occurred, and outputs a reset signal RESET (falling square wave) to the flip-flop 42. The flip-flop 42 holds the reset signal RESET (falling square wave) and switches its output signal to Lo. Since the output signal of the flip-flop 42 is Lo, the selection circuit 5 sets the power control signal PWR_EN2 that it outputs to Lo, and turns off the power supply circuit 3. This makes it possible to appropriately turn off the power supply circuit 3 when an abnormality occurs in the control circuit 1, and prevent unnecessary power consumption.

[0058] 5, when the ignition signal IG is turned off in a normal state, the control circuit 1 switches the power supply control signal PWR_EN1 from Hi to Lo after a predetermined time T1. When the power supply control signal PWR_EN1 switches from Hi to Lo, the power supply of the watchdog circuit 4 is turned off, and the reset signal RESET output by the watchdog timer IC41 and the output signal of the flip-flop 42 switch from Hi to Lo. When either the power supply control signal PWR_EN1 output by the control circuit 1 or the output signal of the flip-flop 42 becomes Lo, the selection circuit 5 sets the power supply control signal PWR_EN2 output by the selection circuit 5 to Lo and turns off the power supply circuit 3.

[0059] The watchdog timer IC41 monitors the square wave WDI until just before the power supply of the watchdog circuit 4 is turned off. WDIf the predetermined time T1 is shorter than the predetermined time T2, the reset signal RESET (a falling rectangular wave) may be output before the power supply control signal PWR_EN1 switches to Lo, and the timing of turning off the power supply circuit 3 may be accelerated. WD Since the time is set to be longer than the predetermined time T1, such a problem is eliminated.

[0060] Although each embodiment has been described above in detail, the present invention is not limited to the specific embodiment, and various modifications and changes are possible within the scope of the claims. In addition, it is also possible to combine all or a plurality of the components of the above-described embodiments. [Explanation of symbols]

[0061] M Vehicle display device 1 Control circuit 2 Display 3 Power circuit 4 Watchdog Circuit 41 Watchdog Timer IC 42 Flip-flop 5 Selection circuit

Claims

1. A display device; a power supply circuit for supplying power to the display; A control circuit for controlling the display device and the power supply circuit based on an external input; a watchdog circuit for determining whether the control circuit is operating normally; a selection circuit that turns off the power supply circuit when a first off signal from the control circuit or a second off signal from the watchdog circuit is input.

2. The watchdog circuit comprises: A watchdog timer IC; The display device for a vehicle according to claim 1 , further comprising: a flip-flop that holds a reset signal from the watchdog timer IC.

3. When the control circuit is operating normally, the control circuit periodically outputs a rectangular wave to the watchdog circuit; The watchdog circuit determines that the control circuit is in an abnormal state when the rectangular wave is not input for a predetermined time period, The display device for a vehicle according to claim 1 , wherein the predetermined time is set to be longer than an expected time until the control circuit generates the first off signal based on an external input.

4. The display device includes: A liquid crystal display element; 4. The vehicle display device according to claim 1, further comprising: a light source for transmitting and illuminating the liquid crystal display element.

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