Virtual image display device

Abstract

To maintain the voltage to be supplied to a processor that controls a head-up display.SOLUTION: A virtual image display device according to the present disclosure comprises: an image display unit having an image creation unit that creates an image and an optical system that projects the image created by the image creation unit on a transmission and reflection unit as image light; and a control unit that controls the image display unit to display a virtual image on the front of a vehicle. The control unit includes: a processor that controls the image display unit; a switch; a second power supply that converts a first voltage supplied from a first power supply through the switch into a second voltage to be supplied to the processor; and a switching unit that switches on and off of the switch on the basis of a first signal from the outside of the control unit and a second signal from the processor.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to a virtual image display device. [Background technology]

[0002] Patent Document 1 describes a head-up display that reduces dark current. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Publication No. 2022-82050 Summary of the Invention [Problem to be solved by the invention]

[0004] Patent Document 1 describes that a fail-safe is realized by keeping on a power supply (first power supply 75) that applies a constant voltage to the control unit after the control unit transitions from a power saving mode to a control mode. However, in Patent Document 1, the power supply (first power supply 75) that applies a constant voltage to the control unit is supplied with voltage from another power supply (third power supply 77) that receives power from the vehicle battery, so even if the control unit controls the power supply (first power supply 75) to be kept on, if the power line from the vehicle battery to that power supply (first power supply 75) is turned off (for example, if the third power supply 77 is turned off), the power supply (first power supply 75) cannot be kept on.

[0005] The present invention aims to maintain the voltage supplied to the processor that controls the head-up display. [Means for solving the problem]

[0006] In order to achieve the above object, one aspect of the present invention is to an image display unit having an image generation unit that generates an image and an optical system that projects the image generated by the image generation unit onto a transmission / reflection unit as image light; a control unit that controls the image display unit to display a virtual image in front of the vehicle; Equipped with The control unit a processor that controls the image display unit; Switch and a second power supply that converts a first voltage supplied from the first power supply via the switch into a second voltage that is supplied to the processor; a switching unit that switches the switch on and off based on a first signal from outside the control unit and a second signal from the processor; The virtual image display device is provided with:

[0007] Other problems and solutions disclosed in the present application will be made clear in the detailed description and drawings. [Effects of the Invention]

[0008] According to the present invention, it is possible to maintain the voltage supplied to the processor that controls the head-up display. [Brief explanation of the drawings]

[0009] [Figure 1] FIG. 1 is an explanatory diagram of the overall configuration of a virtual image display system 1. As shown in FIG. [Figure 2] FIG. 2 is a block diagram of the control unit 20. [Figure 3] Fig. 3A is an explanatory diagram of the power supply unit 30 shown in Fig. 2. Fig. 3B is an explanatory diagram of a power supply unit of a comparative example. [Figure 4] Fig. 4A is a flow chart showing the process of starting up the control unit 20 in this embodiment, and Fig. 4B is a flow chart showing the process of stopping the control unit 20 in this embodiment. [Figure 5] Fig. 5A is a flow diagram of the start-up of a control unit including a power supply unit 30 of the comparative example, and Fig. 5B is a flow diagram of the stop-down of a control unit including a power supply unit of the comparative example. DETAILED DESCRIPTION OF THE INVENTION

[0010] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings. In the following description, identical or similar components may be designated by common reference numerals, and redundant description may be omitted.

[0011] === Implementation form === <Overall structure> FIG. 1 is an explanatory diagram of the overall configuration of a virtual image display system 1. As shown in FIG.

[0012] The virtual image display system 1 is a system that displays an image (virtual image 8) using a head-up display (hereinafter referred to as "HUD"). The virtual image display system 1 includes a vehicle-side control unit 3 and a HUD100.

[0013] The vehicle-side control unit 3 performs various controls of the vehicle and transmits various signals to the HUD 100. The vehicle-side control unit 3 is configured with at least one ECU (Electronic Control Unit). The vehicle-side control unit 3 is connected to the HUD 100 via a signal cable. The vehicle-side control unit 3 transmits signals including image data and control data to the HUD 100. Here, the vehicle-side control unit 3 transmits serial signals to the HUD 100 via a GMSL (Gigabit Multimedia Serial Link).

[0014] The HUD 100 is a virtual image display device mounted on a vehicle and displays a virtual image 8 in front of the vehicle. The HUD 100 is a so-called head-up display. The HUD 100 includes an image display unit 10 and a HUD-side control unit 20. In the following description, the HUD-side control unit may be simply referred to as the "control unit."

[0015] The image display unit 10 is a device that projects an image onto a windshield 9 (front glass) and displays a virtual image 8. The image display unit 10 constitutes the main body of the head-up display. The image display unit 10 includes an image generation unit 11 and an optical system 12.

[0016] The image generation unit 11 generates an image to be projected onto the windshield 9 (front glass). The image generation unit 11 in the figure includes a display unit 11A and a backlight 11B. Here, the image generation unit 11 is configured with a liquid crystal display. The display unit 11A displays an image according to image data. Here, the display unit 11A is configured with a liquid crystal panel. The backlight 11B irradiates light from the back of the display unit 11A (liquid crystal panel). The backlight 11B is configured with, for example, an LED or a light guide plate. Note that the image generation unit 11 is not limited to a liquid crystal display, and may be configured with, for example, an organic EL display device, a micro LED display device, or a projector device using a laser light source.

[0017] The optical system 12 projects the image generated by the image generation unit 11 onto the windshield 9 as image light. Here, the optical system 12 projects light (image light) that has passed through the display unit 11A onto the windshield 9. The optical system 12 is composed of one or more optical elements. The optical elements that make up the optical system 12 include, for example, lenses, mirrors, and prisms. The optical system 12 is configured to display a virtual image 8 to the driver. The windshield 9 transmits light from outside the vehicle while reflecting the image light from the optical system 12. The windshield 9 functions as a transmissive / reflective unit (a so-called half mirror). The driver sees a superimposed image of the background seen through the windshield 9 and the virtual image 8 (spatial image) seen by the reflection of the image light by the windshield 9.

[0018] The HUD 100 (image display unit 10) in the figure has a motor 13. The motor 13 is a drive source that outputs a drive force for moving the mirror of the optical system 12. For example, when the HUD 100 is turned off (described later), the motor 13 moves the mirror of the optical system to a home position. By moving the mirror of the optical system to the home position, it is possible to prevent external light (sunlight) from being irradiated onto the image generation unit 11 (particularly the display unit 11A configured with a liquid crystal panel), and to prevent the image generation unit 11 from becoming too hot. Furthermore, when the HUD 100 is in use, the display position of the virtual image 8 can be adjusted by moving the mirror of the optical system 12 using the drive force of the motor 13.

[0019] The control unit 20 (HUD-side control unit) controls the HUD 100 (image display unit 10). The control unit 20 outputs image data to the display unit 11A of the image generation unit 11 and controls the image to be displayed on the display unit 11A. The control unit 20 also outputs a drive signal to the backlight 11B of the image generation unit 11 and controls the ON / OFF of the backlight 11B and the brightness of the backlight 11B. The control unit 20 also outputs a drive signal to the motor 13 and controls the motor 13, thereby controlling the position of the mirror of the optical system 12.

[0020] FIG. 2 is a block diagram of the control unit 20.

[0021] The control unit 20 (HUD-side control unit) includes a processor 22, a deserializer 23, a driver 24, and a signal converter 26.

[0022] The processor 22 is an IC (Integrated Circuit) that executes various processes. The processor 22 is a so-called microcomputer, and includes a control circuit and a storage circuit (not shown). The control circuit executes a program stored in the storage circuit of the processor 22, thereby executing various processes (described later). The processor 22 has multiple ports. The port 22A is connected to the deserializer 23 and is a data communication port for transmitting and receiving data to and from the deserializer 23. The ports 22B to 22D are control ports used to control the image display unit 10. The port 22B is connected to the display unit 11A and is a display control port for transmitting control signals to the display unit 11A and receiving data (e.g., temperature data) from the display unit 11A. The port 22C is connected to the drive unit 24 that drives the backlight 11B and is a light control port for transmitting and receiving control data (e.g., brightness data for controlling the brightness of the backlight 11B) to and from the drive unit 24. Port 22D is connected to motor 13 via signal conversion unit 26 and is a motor control port for outputting a control signal (e.g., a PWM signal) for controlling motor 13. Ports 22E to 22G are connected to power supply unit 30 (described later) and are ports for power supply control. The configuration of power supply unit 30 and signals input / output between processor 22 and power supply unit 30 will be described later.

[0023] The deserializer 23 converts a serial signal received from the vehicle-side control unit 3 (serializer 5) into a parallel signal. The serial signal includes image data, control data, etc., and the deserializer 23 generates image data (RGB data) and control data by converting the serial signal into a parallel signal. The deserializer 23 has multiple ports. The port 23A is connected to the serializer 5 of the vehicle-side control unit 3 via a signal cable, and receives the serial signal from the serializer 5. The port 23B is connected to the display unit 11A of the image generation unit 11, and the image data included in the serial signal is transmitted from the port 23B to the display unit 11A. The port 23C is connected to the processor 22 and is a data communication port for transmitting and receiving data to and from the processor 22.

[0024] The driver 24 drives the backlight 11B. Here, the driver 24 is an LED driver. The driver 24 is connected to the processor 22. The driver 24 drives the backlight 11B based on control data received from the processor 22. For example, the driver 24 receives brightness data indicating brightness from the processor 22, and controls the drive signal (current) of the LED of the backlight 11B based on the brightness data.

[0025] The signal conversion unit 26 converts the control signal (PWM signal) output from the processor 22 into a drive signal to drive the motor 13. If the HUD 100 does not include the motor 13, the control unit 20 does not need to include the signal conversion unit 26.

[0026] The control unit 20 (HUD-side control unit) also has a power supply unit 30. The power supply unit 30 controls the power supply of the control unit 20. A battery power supply (+B power supply) is connected to the power supply unit 30. A voltage of 12 V is supplied to the power supply unit 30 from the battery power supply through a power line.

[0027] Fig. 3A is an explanatory diagram of the power supply unit 30 shown in Fig. 2. Fig. 3B is an explanatory diagram of the power supply unit 30 of a comparative example. First, the comparative example of Fig. 3B will be described, and then the configuration of Fig. 3A will be described.

[0028] The power supply unit 30 of the comparative example includes a PoC filter 31, a switch 32, and a voltage conversion unit 33.

[0029] The PoC filter 31 is a filter that separates a signal from a power supply (superimposed voltage). Power is superimposed on a signal cable between the vehicle-side control unit 3 (specifically, the serializer 5) and the control unit 20 (specifically, the deserializer 23) (see FIG. 2 ). The PoC filter 31 separates the power supply (superimposed voltage) from the signal (e.g., image data or control data) on the signal cable, and the separated superimposed voltage generates a signal (start signal / stop signal) for controlling the ON / OFF of the switch 32. In other words, the power supply (superimposed voltage) superimposed on the signal transmitted through the signal cable is used as the signal for controlling the ON / OFF of the switch 32. In the following description, a signal (here, the superimposed voltage) that turns the switch ON / OFF from the vehicle-side control unit 3 (outside the control unit 20) may be referred to as an “external signal” or a “first signal.” The external signal does not have to be generated by the PoC filter 31 (the external signal does not have to be a superimposed voltage). For example, if power is not superimposed on the signal of the signal cable, the PoC filter 31 may be omitted.

[0030] The switch 32 is a circuit (power cutoff circuit) for connecting and disconnecting the power line. One end of the switch 32 is connected to a battery power supply (+B power supply), and the other end is connected to a voltage conversion unit 33. The switch 32 of the comparative example shown in FIG. 3A is turned on and off by an external signal (the superimposed voltage separated by the PoC filter 31).

[0031] The voltage conversion unit 33 converts the voltage (12 V from the battery power supply) input from the power line via the switch 32 into a voltage (3.3 V in this case) to be supplied to the processor 22. The voltage conversion unit 33 is configured with a circuit (DC / DC converter) that drops the voltage. The voltage conversion unit 33 functions as a power supply (3.3 V power supply) that outputs a voltage of 3.3 V. The 3.3 V power supply voltage output by the voltage conversion unit 33 is used as the power supply voltage for the processor 22. The 3.3 V power supply voltage output by the voltage conversion unit 33 may also be used as the power supply voltage for the deserializer 23, for example, or may be used to drive the display unit 11A. The voltage conversion unit 33 outputs a PG signal when the 3.3 V power supply voltage has stabilized (see FIG. 2). The PG signal is output to port 22E of the processor 22 to reset the processor 22. Port 22E is a reset port through which the PG signal from the voltage conversion unit 33 is input.

[0032] The battery power supply (+B power supply) may be referred to as the "first power supply" or "external power supply," and the voltage conversion unit 33 (the power supply that supplies a voltage of 3.3V to the processor 22) may be referred to as the "second power supply" or "3.3V power supply." The 12V voltage supplied from the battery power supply (+B power supply) may be referred to as the "first voltage," and the 3.3V voltage supplied from the voltage conversion unit 33 (the voltage supplied to the processor 22) may be referred to as the "second voltage."

[0033] FIG. 5A is a flow chart showing the start-up of a control unit including a power supply unit 30 according to a comparative example. When power supply from the signal cable of the vehicle-side control unit 3 starts, an external signal (superimposed voltage) is turned on, and switch 32 is turned on. When the switch is turned on by the external signal, a 12V battery power supply voltage is supplied to voltage conversion unit 33, and voltage conversion unit 33 (3.3V power supply) is turned on. Voltage conversion unit 33 steps down the 12V voltage to 3.3V and supplies the 3.3V power supply voltage to processor 22, turning processor 22 on. More specifically, voltage conversion unit 33 supplies the 3.3V power supply voltage to processor 22 and outputs a PG signal to processor 22 when the 3.3V power supply voltage has stabilized. Processor 22 is reset by the PG signal, and processor 22 is started up.

[0034] FIG. 5B is a flow diagram of a comparative example when a control unit including power supply unit 30 is stopped. When the power supply from the signal cable of the vehicle-side control unit 3 is stopped, the external signal (superimposed voltage) is turned off, and the switch 32 is turned off. When the external signal turns off the switch 32, the supply of the battery power supply voltage to the voltage conversion unit 33 (3.3 V power supply) is stopped, and the voltage conversion unit 33 is turned off. When the voltage conversion unit 33 is turned off, the supply of the 3.3 V power supply voltage to the processor 22 is stopped, and the processor 22 is turned off. In the comparative example, when the power supply from the signal cable is stopped (when the external signal is turned off), the supply of the 3.3V power supply voltage to the processor 22 is immediately cut off. Therefore, in the comparative example, the processor 22 cannot perform the termination process (described later).

[0035] Next, the power supply unit 30 shown in FIG. 3A (the power supply unit 30 shown in FIG. 2) will be described. The power supply unit 30 shown in FIG. 3A has a PoC filter 31, a switch 32, a voltage conversion unit 33, and a switching unit 34. The processor 22 is configured to output a signal from a port 22F to the switching unit 34. In the following description, the signal output from the processor 22 to the switching unit 34 may be referred to as a "sustain signal" or a "second signal." The port 22F is an output port for outputting the sustain signal.

[0036] The switching unit 34 switches the switch 32 ON / OFF based on the external signal (superimposed voltage) and the sustain signal from the processor 22. The switching unit 34 outputs a switch control signal to the switch 32, and the switch 32 is configured to be controlled to be ON / OFF by the switch control signal output from the switching unit 34. The switching unit 34 outputs the switch control signal based on the external signal (superimposed voltage) and the sustain signal. The switching unit 34 turns the switch 32 ON (outputs a switch control signal that turns the switch 32 ON) when at least one of the external signal and the sustain signal indicates ON. Furthermore, the switching unit 34 turns the switch 32 OFF (outputs a switch control signal that turns the switch 32 OFF) when both the external signal and the sustain signal indicate OFF. Here, the switching unit 34 is configured by an OR circuit. However, the switching unit 34 is not limited to an OR circuit.

[0037] FIG. 4A is a flow chart showing the start-up of the control unit 20 in this embodiment. The processing of S101 to S103 in the figure is the same as the processing of the comparative example shown in FIG. 5A. That is, when power supply from the signal cable of the vehicle-side control unit 3 starts, an external signal (superimposed voltage) is turned on, and the switch 32 is turned on (S101). When the external signal turns on the switch 32, a 12V battery power supply voltage is supplied to the voltage conversion unit 33 (3.3V power supply), and the voltage conversion unit 33 is turned on (S102). The voltage conversion unit 33 steps down the 12V voltage to 3.3V and supplies the 3.3V power supply voltage to the processor 22, and the processor 22 is turned on (S103). In more detail, the voltage conversion unit 33 supplies the 3.3V power supply voltage to the processor 22, and outputs a PG signal to the processor 22 when the 3.3V power supply voltage has stabilized. The processor 22 is reset by the PG signal, and the processor 22 is started up.

[0038] After the processor 22 is started, the processor 22 performs initial settings on the deserializer 23 to start it. After the deserializer 23 is started, the deserializer 23 transmits image data received from the vehicle-side control unit 3 (serializer 5) to the display unit 11A of the image generation unit 11, and transmits control data received from the vehicle-side control unit 3 to the processor 22. The processor 22 controls the image display unit 10 (display unit 11A, backlight 11B, motor 13) based on the control data from the deserializer 23. This allows the control unit 20 to control the image display unit 10 based on the signals (image data, control data) received from the vehicle-side control unit 3, and display the virtual image 8. That is, control of the HUD 100 is started.

[0039] In this embodiment, after the processor 22 is started (after S103), the processor 22 turns on the sustain signal that it outputs to the switching unit 34 (S104). The sustain signal is a signal for maintaining the switch 32 in an on state. The switching unit 34 is configured to turn on the switch 32 when at least one of the external signal and the sustain signal is on. Therefore, when the sustain signal from the processor 22 indicates on, the switching unit 34 maintains the switch 32 on regardless of whether the external signal is on or off (continuously outputs a switch control signal that turns on the switch 32). While the processor 22 keeps the sustain signal on, the switch 32 is maintained on, so the voltage conversion unit 33, which is a 3.3V power supply, is maintained on, and the supply of the 3.3V power supply voltage to the processor 22 is maintained. Therefore, while the processor 22 keeps the sustain signal on, even if the external signal is turned off, the switch 32 is maintained on, and the supply of the 3.3V power supply voltage to the processor 22 is maintained.

[0040] FIG. 4B is a flow diagram when the control unit 20 is stopped in this embodiment.

[0041] When the power supply from the signal cable of the vehicle-side control unit 3 is stopped, the external signal (superimposed voltage) is turned off. However, immediately after the external signal (superimposed voltage) changes from on to off, the processor 22 keeps the sustain signal on, so the switching unit 34 keeps the switch 32 on even when the external signal is turned off. Therefore, immediately after the external signal (superimposed voltage) changes from on to off, the switch 32 is kept on, and the supply of the 3.3V power supply voltage to the processor 22 is maintained.

[0042] The external signal is input to the switching unit 34 and also to a port 22G of the processor 22 (see FIGS. 2 and 3A). The port 22G is a monitoring port for monitoring the external signal, and the processor 22 monitors the external signal via the port 22G.

[0043] When the external signal is turned off, the processor 22 executes a shutdown process for the image display unit 10 (S111). For example, as the shutdown process of S111, the processor 22 outputs a control signal to the display unit 11A according to a predetermined power-off sequence. By terminating the operation of the display unit 11A according to the predetermined power-off sequence, damage to the display unit 11A (for example, image fixation on the liquid crystal panel) can be suppressed. Furthermore, as the shutdown process of S111, the processor 22 outputs a drive signal to the motor 13 to move the mirror of the optical system 12 to the home position. By moving the mirror to the home position, it is possible to suppress irradiation of the image generation unit 11 with external light (sunlight) and prevent the image generation unit 11 from becoming too hot. In this way, by the processor 22 executing the shutdown process for the image display unit 10, it is possible to suppress damage to the image display unit 10. Note that the shutdown process for the image display unit 10 is not limited to this, and other processes (for example, turning off the backlight) may also be used.

[0044] After completing the termination process (YES in S112), the processor 22 turns off the sustain signal that it outputs to the switching unit 34 (S113). As already explained, the switching unit 34 is configured to turn off the switch 32 when both the external signal and the sustain signal are off. Because the external signal input to the switching unit 34 is already off, when the sustain signal from the processor 22 turns off, the switching unit 34 turns off the switch 32 (S114). When the switch 32 turns off, the supply of the battery power supply voltage to the voltage conversion unit 33 (3.3V power supply) stops, and the voltage conversion unit 33 turns off (S115). When the voltage conversion unit 33 turns off, the supply of the 3.3V power supply voltage to the processor 22 stops, and the processor 22 turns off (S116).

[0045] 4B, after the power supply from the signal cable is stopped (after the external signal is turned off), the processor 22 can execute the termination process before the switch 32 is turned off. Therefore, in this embodiment, it is possible to suppress malfunctions of the HUD 100 (for example, damage to the display unit 11A) compared to the comparative example.

[0046] Incidentally, in a configuration in which the processor 22 is placed in sleep mode, although the power consumption of the processor 22 is reduced, the supply of power to the processor 22 itself is not cut off, resulting in dark current (standby current) being consumed from the battery power supply. In contrast, in this embodiment, the power line connected to the battery power supply is cut off by the switch 32, and the input of voltage to the voltage conversion unit 33 (the 3.3 V power supply that supplies voltage to the processor 22) is cut off, so that the dark current (standby current) can be reduced. Also, in this embodiment, the switch 32 is turned from off to on by an external signal, so that the dark current (standby current) can be reduced (for example, if the switch 32 were turned from off to on by a signal from the processor 22, the configuration would result in the consumption of dark current (standby current).

[0047] Furthermore, in this embodiment, immediately before the switch 32 is turned on, the power line is interrupted by the switch 32, and the power supply to the processor 22 is cut off. In other words, the timing when the switch 32 changes from off to on is clearly the timing when the HUD 100 starts up (in contrast, when the sleep mode of the processor 22 is used, the timing when the processor 22 starts up from the sleep mode is not necessarily the timing when the HUD 100 starts up). For this reason, when the switch 32 is turned on, the HUD 100 may display an opening image as a virtual image. Furthermore, in this embodiment, the vehicle-side control unit 3 outputs an external signal (superimposed voltage) and a signal including image data and control data to the control unit 20 via the signal cable, so the vehicle-side control unit 3 controls both the timing of turning on the switch 32 and the image (virtual image) to be displayed on the HUD 100. In other words, the vehicle-side control unit 3 turns on the switch 32 by starting to supply power to the HUD 100 via the signal cable (by outputting the superimposed voltage, which serves as an external signal, to the signal cable), and then transmits a signal including image data and control data for displaying an opening image to the HUD 100 via the signal cable, thereby causing the HUD 100 to display an opening image when the HUD 100 is started up. Therefore, this embodiment has a structure suitable for displaying an opening image on the HUD 100 when the HUD 100 is started up.

[0048] In addition, as long as the processor 22 can detect that power supply from the signal cable has stopped, the configuration is not limited to one in which the processor 22 monitors an external signal as shown in Figure 3A, and the processor 22 may be configured to monitor other signals.

[0049] <Summary> The HUD 100 (virtual image display device) includes an image display unit 10 and a control unit 20. The image display unit 10 includes an image generation unit 11 and an optical system 12 that projects an image generated by the image generation unit 11 onto a windshield 9 (transmissive / reflective unit) as image light. The control unit 20 controls the image display unit 10 to display a virtual image 8 in front of the vehicle. In this embodiment, the control unit 20 includes a processor 22, a switch 32, a voltage conversion unit 33 (second power source) that converts a 12V voltage (first voltage) supplied from a battery power source (first power source) via the switch 32 into a 3.3V voltage (second voltage), and a switching unit 34. The switching unit 34 switches the switch 32 on and off based on an external signal (first signal) and a sustain signal (second signal) from the processor 22. This allows the switch 32 to be maintained on even when the external signal is turned off, thereby maintaining the supply of 3.3V (second voltage) to the processor 22.

[0050] Furthermore, the switching unit 34 is configured to turn on the switch 32 when at least one of the external signal (first signal) and the sustain signal (second signal) indicates an on state, and to turn off the switch 32 when both the external signal and the sustain signal indicate an off state. As a result, even if the external signal turns off, the switch 32 is maintained on, and the supply of 3.3 V (second voltage) to the processor 22 can be maintained.

[0051] A power supply superimposed signal cable is connected to the control unit 20, and the external signal (first signal) is a signal separated from the signal cable via the PoC filter 31. This allows the control unit 20 to be configured so that when power supply from the signal cable starts, an external signal (first signal) indicating ON is input to the switching unit 34, and when power supply from the signal cable stops, an external signal indicating OFF is input to the switching unit 34. In other words, the external signal input to the switching unit 34 can be switched ON / OFF depending on whether or not power is being supplied from the signal cable.

[0052] Furthermore, when the power supply from the signal cable is stopped, the processor 22 performs a shutdown process for the image display unit 10 (S111 in FIG. 4B ), and after this shutdown process, outputs an OFF maintaining signal (a second signal that turns off the switch 32) (S113), and the switching unit 34 turns off the switch 32 based on the external signal and the maintaining signal (S114). This prevents damage to the image display unit 10. Note that, as the shutdown process (S111), the processor 22 preferably executes a power-off sequence for the liquid crystal panel (display unit 11A) of the image generation unit 11. This prevents damage to the liquid crystal panel (e.g., image fixation). Also, as the shutdown process (S111), the processor 22 preferably outputs a drive signal to a motor to move the mirror of the optical system 12 to a home position (a predetermined position). This prevents external light (sunlight) from irradiating the image generation unit 11, and prevents the image generation unit 11 from becoming too hot.

[0053] Although the embodiments of the present invention have been described in detail above, the present invention is not limited to the above embodiments and includes various modifications. Furthermore, the above embodiments have been described in detail to clearly explain the present invention, and the present invention is not necessarily limited to those including all of the described configurations. Furthermore, some of the configurations of the above embodiments can be added to, deleted from, or replaced with other configurations. [Explanation of symbols]

[0054] 1 Virtual image display system, 3 Vehicle side control unit, 5 Serializer, 8 Virtual image, 9 Windshield, 10 image display unit, 11 image generation unit, 11A Display, 11B Backlight, 12 Optical system, 13 Motor, 20 HUD side control unit (control unit), 22 processors, 22A-22G ports, 23 Deserializer, 24 drive unit, 26 signal conversion unit, 31 PoC filters, 32 switches, 33 voltage conversion unit (second power supply), 34 switching unit, 100 HUD

Claims

1. an image display unit having an image generation unit that generates an image and an optical system that projects the image generated by the image generation unit onto a transmission / reflection unit as image light; a control unit that controls the image display unit to display a virtual image in front of the vehicle; Equipped with The control unit a processor that controls the image display unit; Switch and a second power supply that converts a first voltage supplied from the first power supply via the switch into a second voltage that is supplied to the processor; a switching unit that switches the switch on and off based on a first signal from outside the control unit and a second signal from the processor; A virtual image display device comprising:

2. The virtual image display device according to claim 1, When at least one of the first signal and the second signal indicates ON, the switching unit turns on the switch; The virtual image display device, wherein the switching unit turns off the switch when both the first signal and the second signal indicate off.

3. The virtual image display device according to claim 1 or 2, A power supply superimposed signal cable is connected to the control unit, The virtual image display device is characterized in that the first signal is a signal separated from the signal cable.

4. The virtual image display device according to claim 3, When power supply from the signal cable is stopped, the processor performs a termination process for the image display unit, and after the termination process, outputs the second signal to turn off the switch; The virtual image display device according to claim 1, wherein the switching unit turns off the switch based on the first signal and the second signal.

5. The virtual image display device according to claim 4, the image generating unit includes a liquid crystal panel, A virtual image display device characterized in that when power supply from the signal cable is stopped, the processor performs the termination processing for the liquid crystal panel, and after the termination processing, outputs the second signal to turn off the switch.

6. The virtual image display device according to claim 4, the optical system includes a mirror that is moved by a motor; When power supply from the signal cable is stopped, the processor performs the termination process on the motor to move the mirror to a predetermined position, and after the termination process, outputs the second signal to turn off the switch.

7. The virtual image display device according to claim 4, The virtual image display device is characterized in that the processor detects that power supply from the signal cable has stopped based on the first signal.

Images