JP7514720B2 - Display device and control method thereof - Google Patents

Description

The present invention relates to a display device and a control method thereof.

Conventionally, rear seat entertainment systems (RSE) have been developed that provide video and audio to passengers sitting in the rear seats of a vehicle (see, for example, Patent Document 1). The rear seat entertainment system includes a display device that can be viewed while hanging from the ceiling member of the vehicle, and speakers installed inside the vehicle.

The input video signal and allowable power supply voltage specifications for the display device of a rear seat entertainment system vary depending on the model of the vehicle in which the display device is installed.

JP 2017-144916 A

When designing a display device that can only handle input video signals and allowable power supply voltage specifications, it is necessary to design a display device separately for each different input video signal and allowable power supply voltage specification.

Even if the input video signal and allowable power supply voltage specifications are different, if it is possible to design a common display device that can accommodate each of the different specifications, it will be possible to reduce manufacturing labor hours, management costs, etc.

In view of the above problems, the present invention aims to provide a display device and a control method thereof that can accommodate different specifications, even if the input video signal and allowable power supply voltage specifications are different.

The display device according to the present invention includes a plurality of input terminals, a display unit that displays an image based on an externally provided video signal, a detection unit that detects which of the plurality of input terminals the video signal is being input to, and a control unit that monitors a power supply voltage and turns off the display unit when the power supply voltage falls below a threshold, and the control unit is configured to switch the threshold based on the detection result of the detection unit (first configuration).

In the display device of the first configuration, the control unit may include a plurality of judgment circuits each having a different threshold value and a microcomputer that controls turning off the display unit, and each of the plurality of judgment circuits monitors the power supply voltage and judges whether the power supply voltage has fallen below the threshold value, and the microcomputer may determine which judgment result of the plurality of judgment circuits to use based on the detection result of the detection unit (second configuration).

In the display device of the first configuration, the control unit may include a microcomputer, the power supply voltage is input to an AD input port of the microcomputer, and the microcomputer may be configured to AD convert the power supply voltage and monitor it (third configuration).

In the display device of the first configuration, the control unit includes a determination circuit that monitors the power supply voltage and determines whether the power supply voltage falls below the threshold, and a microcomputer that turns off the display unit based on the determination result of the determination circuit, and the determination circuit may be configured to be capable of switching the threshold (fourth configuration).

In the display device of any of the first to fourth configurations described above, the control unit may be configured to set the initial value of the threshold to the maximum value among the threshold switching candidates (fifth configuration).

The control method according to the present invention is a control method for a display device having a plurality of input terminals and a display unit that displays an image based on an externally provided video signal, and includes a detection step of detecting which of the plurality of input terminals the video signal is input to, and a turn-off step of monitoring a power supply voltage and turning off the display unit when the power supply voltage falls below a threshold, the turn-off step including a switching step of switching the threshold based on the detection result of the detection step (sixth configuration).

The display device and control method according to the present invention can accommodate different specifications, even if the input video signal and allowable power supply voltage specifications are different.

FIG. 1 is a diagram showing an example of mounting the display device according to an embodiment; FIG. 1 is a perspective view of a display device according to an embodiment; FIG. 13 is a perspective view of a display device according to a modified example. FIG. 1 is a diagram showing a first schematic configuration example of a display device according to an embodiment; FIG. 2 is a diagram showing a second schematic configuration example of the display device according to the embodiment; FIG. 13 is a diagram showing a third schematic configuration example of a display device according to an embodiment; 1 is a flowchart showing an example of the operation of a display device according to an embodiment. FIG. 13 is a diagram showing an example of a display screen of a display unit.

An exemplary embodiment of the present invention will now be described in detail with reference to the drawings.

The display device 1 according to the embodiment is mounted on a vehicle. FIG. 1 is a diagram showing an example of how the display device 1 is attached. In the example shown in FIG. 1, the display device 1 is attached to the ceiling of the vehicle and provides images to passengers sitting in the rear seats of the vehicle.

The display device 1 includes a base 2 fixed to the ceiling of the vehicle, a housing 3 that can be opened and closed relative to the base 2, and a hinge 4 (see FIG. 2) provided between the base 2 and the housing 3. The housing 3 incorporates a display unit. In this embodiment, as shown in FIG. 2, the display screen 5 of the display unit is provided on the inner surface of the housing 3, and when the housing 3 is closed relative to the base 2 (when the opening and closing angle θ is set to 0°), the display screen 5 of the display unit is hidden. On the other hand, unlike this embodiment, the display screen 5 of the display unit may be provided on the outer surface of the housing 3, and when the housing 3 is closed relative to the base 2 (when the opening and closing angle θ is set to 0°), the display screen 5 of the display unit may be exposed, as in the display device 1' according to the modified example shown in FIG. 3.

<First Schematic Configuration Example of Display Device>
4 is a diagram showing a first schematic configuration example of the display device 1. The display device 1 of the first schematic configuration example includes a microcomputer 11, an image IC 12, a display unit 13, a drive mechanism 14, a detection unit 15, a first determination IC 16A, a second determination IC 16B, a first input terminal T1, and a second input terminal T2.

The microcomputer 11 controls the entire display device 1. In detail, the microcomputer 11 includes a CPU (Central Processing Unit) that performs calculations to realize various control functions, a RAM (Random Access Memory) that serves as a working area for the calculations, and a non-volatile memory that stores various data.

The microcomputer 11 generates a first PWM (Pulse Width Modulation) drive signal S1. Specifically, when the microcomputer 11 receives an instruction for electric tilt transmitted from an operating device such as a remote control transmitter, it generates the first PWM drive signal S1. The first PWM drive signal S1 is supplied to the drive mechanism 14. The microcomputer 11 also generates a second PWM drive signal S2. Specifically, when the microcomputer 11 is notified by the display unit 13 through SPI (Serial Peripheral Interface) communication that the display unit 13 is receiving a video signal S3 from the video IC 12, it generates an on-duty second PWM drive signal S2 based on the output signal of an illuminance sensor that detects the ambient illuminance of the display device 1. The second PWM drive signal S2 is supplied to the display unit 13.

When the video IC 12 receives a video signal provided from outside the display device 1 via the first input terminal T1 and the first detection IC 15A or via the second input terminal T2 and the second detection IC 15B, it supplies the video signal S3 obtained by performing various video processing on the received video signal to the display unit 13. The video IC 12 can perform video processing to superimpose an OSD (On Screen Display) signal provided from the microcomputer 11 on the video signal provided from the outside of the display device 1 via the first input terminal T1 and the first detection IC 15A or via the second input terminal T2 and the second detection IC 15B. The video IC 12 can also supply only the OSD signal provided from the microcomputer 11 as the video signal S3 to the display unit 13. The format of the video signal S3 provided from the video IC 12 to the display unit 13 is not particularly limited, but in this embodiment, it is a video signal in LVDS (Low Voltage Differential Signaling) format. In addition, in this embodiment, the video signal supplied from the first detection IC 15A to the video IC 12 and the video signal supplied from the second detection IC 15B to the video IC 12 are also LVDS format video signals.

The display unit 13 displays an image based on the video signal S3. The display unit 13 includes a display drive IC 13A and a display panel 13B. The front surface of the display panel 13B becomes the display screen 5 of the display unit 13.

The display drive IC 13A sets each pixel value of the display unit 13 based on the RGB data of the video signal S3, sets the brightness of the display unit 13 based on the on-duty of the second PWM drive signal S2, and drives the display panel 13B based on these settings. In addition, while the display drive IC 13A is receiving the video signal S3, it notifies the microcomputer 11 via SPI communication that it is receiving a video signal from the video IC 12.

The display panel 13B is a self-luminous display panel such as an OLED (Organic Light Emitting Diode). Note that, unlike this embodiment, if the display panel 13B is a non-self-luminous display panel, a backlight that irradiates light onto the display panel is provided, and the display drive IC 13A drives the display panel based on the settings of the pixel values of the display unit 13, and drives the backlight based on the brightness setting of the display unit 13.

The drive mechanism 14 varies the inclination of the display unit 13. Specifically, the drive mechanism 14 rotates the housing 3 relative to the base unit 2 to vary the inclination of the display unit 13 relative to the base unit 2. The drive mechanism 14 includes a motor drive IC 14A and a rotation actuator 14B. The rotation actuator 14B includes a motor 14C. The motor drive IC 14A drives the motor 14C at a rotation speed based on the on-duty of the first PWM drive signal S1. The rotation actuator 14B rotates the housing 3 relative to the base unit 2 at a movement speed of the display unit 13 that corresponds to the rotation speed of the motor 14C.

The drive mechanism 14 may be removed from the display device 1, and the housing 3 may be opened and closed manually relative to the base unit 2.

The detection unit 15 detects to which of the first input terminal T1 and the second input terminal T2 a video signal is being input. The detection unit 15 includes a first detection IC 15A and a second detection IC 15B.

The first detection IC 15A is provided between the first input terminal T1 and the video IC 12, and when a video signal is input to the first input terminal T1, it notifies the microcontroller 11 that a video signal is input to the first input terminal T1.

The second detection IC 15B is provided between the second input terminal T2 and the video IC 12, and when a video signal is input to the second input terminal T2, it notifies the microcontroller 11 that a video signal is input to the second input terminal T2.

The output terminal of the external device that outputs a video signal of the first specification is connected to the first input terminal T1, and the output terminal of the external device that outputs a video signal of the second specification is connected to the second input terminal T2. The vehicle is equipped with either an external device that outputs a video signal of the first specification or an external device that outputs a video signal of the second specification.

A control unit constituted by the first determination IC 16A, the second determination IC 16B and the microcomputer 11 monitors the battery output voltage V _BAT , which is the power supply voltage, and turns off the display unit 13 when the battery output voltage V _BAT falls below a threshold value.

The control unit switches the threshold value based on the detection result of the detection unit 15. The first determination IC 16A has a threshold value TH of voltage V1, monitors the battery output voltage _VBAT , and determines whether the battery output voltage _VBAT has fallen below the threshold value. The second determination IC 16B has a threshold value TH of voltage V2 (<V1), monitors the battery output voltage _VBAT , and determines whether the battery output voltage _VBAT has fallen below the threshold value.

The microcomputer 11 uses the determination result of the first determination IC 16A when it receives a notification from the first detection IC 15A that a video signal is being input to the first input terminal T1, and uses the determination result of the second determination IC 16B when it receives a notification from the second detection IC 15B that a video signal is being input to the second input terminal T2. The microcomputer 11 then turns off the display unit 13 when the battery output voltage V _BAT falls below a threshold. Specifically, the microcomputer 11 sets the on-duty of the second PWM drive signal to 0% when the battery output voltage V _BAT falls below a threshold.

In the display device 1 of the first schematic configuration example, a first judgment IC 16A and a second judgment IC 16B are provided, each of which has a different numerical value for the threshold value TH, so that the processing of the microcomputer 11 related to threshold value switching can be limited to the selection of the judgment result of the first judgment IC 16A or the judgment result of the second judgment IC 16B based on the detection result of the detection unit 15. In other words, in the display device 1 of the first schematic configuration example, the load on the microcomputer 11 related to threshold value switching can be reduced.

<Second Schematic Configuration Example of Display Device>
5 is a diagram showing a second schematic configuration example of the display device 1. The display device 1 of the second schematic configuration example differs from the display device 1 of the first schematic configuration example in that it does not include the first determination IC 16A and the second determination IC 16B.

The battery output voltage V _BAT is supplied to the AD input port P1 of the microcomputer 11. The microcomputer 11 performs AD conversion on the battery output voltage V _BAT , which is an analog voltage input to the AD input port P1, and monitors it. When the microcomputer 11 receives a notification from the first detection IC 15A that a video signal is input to the first input terminal T1, the microcomputer 11 sets the threshold value TH to voltage V1, and when the microcomputer 11 receives a notification from the second detection IC 15B that a video signal is input to the second input terminal T2, the microcomputer 11 sets the threshold value TH to voltage V2 (<V1). Furthermore, the microcomputer 11 determines whether the battery output voltage V _BAT has fallen below the threshold value TH, and turns off the display unit 13 when the battery output voltage V _BAT falls below the threshold value TH.

In the display device 1 of the second schematic configuration example, the microcomputer 11 determines whether the battery output voltage V _BAT has fallen below the threshold TH, so there is no need for a dedicated circuit for determining whether the battery output voltage V _BAT has fallen below the threshold TH. In other words, the number of parts can be reduced in the display device 1 of the second schematic configuration example.

<Third Schematic Configuration Example of Display Device>
6 is a diagram showing a third schematic configuration example of the display device 1. The display device 1 of the third schematic configuration example differs from the display device 1 of the first schematic configuration example in that the display device 1 of the third schematic configuration example includes a judgment IC 16 instead of the first judgment IC 16A and the second judgment IC 16B.

The judgment IC 16 judges whether the output voltage V _BAT of the battery falls below the threshold TH. The judgment IC 16 can switch the threshold TH. Specifically, the judgment IC 16 switches the value of the threshold TH to either a voltage V1 or a voltage V2 (<V1) in accordance with an instruction from the microcomputer 11.

When the microcomputer 11 receives a notification from the first detection IC 15A that a video signal is being input to the first input terminal T1, it instructs the judgment IC 16 to switch the value of the threshold TH to voltage V1. When the microcomputer 11 receives a notification from the second detection IC 15B that a video signal is being input to the second input terminal T2, it instructs the judgment IC 16 to switch the value of the threshold TH to voltage V2.

In the display device 1 of the third schematic configuration example, the determination IC 16 is capable of switching the threshold value TH, so that it is possible to reduce the number of dedicated circuits for determining whether the battery output voltage V _BAT has fallen below the threshold value TH.

<Example of operation of the display device>
Fig. 7 is a flowchart showing an example of the operation of the display device 1. When the supply of the output voltage of a DC/DC converter provided between the battery and the display device 1 to the display device 1 is started, the display device 1 is started and the flow operation shown in Fig. 7 is started.

The display device 1 is configured on the assumption that a vehicle equipped with an external device that outputs a video signal of the first specification is equipped with a DC/DC converter without a boost function, and a vehicle equipped with an external device that outputs a video signal of the second specification is equipped with a DC/DC converter with a boost function. In other words, when a video signal of the second specification is input, the display device 1 can normally display an image up to a lower value of the battery output voltage V _BAT compared to when a video signal of the first specification is input, and therefore does not turn off the display unit 13 until the battery output voltage V _BAT becomes a lower value.

Even if the display unit 13 is mounted on the vehicle together with an external device that outputs a video signal of the first specification, in order to prevent the display unit 13 from displaying an abnormal image at startup, the threshold value TH is set to voltage V1 at the start of the flow operation shown in FIG. 7. That is, the control unit including the microcomputer 11 sets the initial value of the threshold value TH (the value of the threshold value TH immediately after the display unit 1 is started) to the maximum value among the switching candidates for the threshold value TH.

If the display unit 13 receives the video signal S3 from the video IC 12 after the startup of the display device 1 is complete, the display unit 13 displays an image based on the video signal S3. In other words, if the display unit 13 receives the video signal S3 from the video IC 12 after the startup of the display device 1 is complete, the display unit 13 turns on.

After the start-up of the display device 1 is completed, the control unit including the microcomputer 11 determines whether the output voltage V _BAT of the battery has fallen below the threshold value TH (step S10).

When the battery output voltage V _BAT falls below the threshold TH (YES in step S10), the microcomputer 11 turns off the display unit 13 (step S20), and then proceeds to step S30. After executing step S20, the control unit including the microcomputer 11 monitors the battery output voltage V _BAT , and when the battery output voltage V _BAT exceeds the light-off cancellation threshold TH'(>TH), cancels the light-off of the display unit 13 and turns on the display unit 13.

If the battery output voltage V _BAT does not fall below the threshold value TH (NO in step S10), step S20 is skipped and the process proceeds to step S30.

In step S30, the microcontroller 11 checks whether or not a video signal is being input to the first input terminal T1 based on the detection result of the detection unit 15. In other words, the microcontroller 11 checks whether or not a notification that a video signal is being input to the first input terminal T1 has been received from the first detection IC 15A.

If a video signal is being input to the first input terminal T1 (YES in step S30), the control unit including the microcomputer 11 sets the threshold value TH to voltage V1 (step S40) and then returns to step S10.

If no video signal is being input to the first input terminal T1 (NO in step S30), proceed to step S50.

In step S50, the microcontroller 11 checks whether or not a video signal is being input to the second input terminal T2 based on the detection result of the detection unit 15. In other words, the microcontroller 11 checks whether or not a notification that a video signal is being input to the second input terminal T2 has been received from the second detection IC 15B.

If a video signal is being input to the second input terminal T2 (YES in step S50), the control unit including the microcomputer 11 sets the threshold value TH to voltage V2 (step S60) and then returns to step S10.

If no video signal is input to the second input terminal T2 (NO in step S50), the microcomputer 11 generates an OSD signal to change the display screen of the display unit 13 to the display screen shown in FIG. 8, and supplies the OSD signal to the video IC 12. The video IC 12 supplies the OSD signal to the display unit 13 as a video signal S3 (step S70), and then returns to step S10. In the display screen shown in FIG. 8, only the text "No Signal" is displayed with white pixels, and the remaining parts are displayed with black pixels.

According to the flow operation shown in FIG. 7, when the video signal input to the display device 1 is of the first specification, the lower limit of the allowable battery output voltage V _BAT can be set to voltage V1, and when the video signal input to the display device 1 is of the second specification, the lower limit of the allowable battery output voltage V _BAT can be set to voltage V2. That is, according to the flow operation shown in FIG. 7, even if the specifications of the video signal input to the display device 1 and the allowable power supply voltage are different, the display device 1 can accommodate each of the different specifications. As a result, even if the specifications of the video signal input to the display device 1 and the allowable power supply voltage are different, the display device 1 can be designed to be common. Therefore, the manufacturing man-hours and management costs of the display device 1 can be reduced.

<Modification>
The above-described embodiments should be considered in all respects as illustrative and not restrictive, and the technical scope of the present invention is indicated by the claims, not by the description of the above-described embodiments, and should be understood to include all modifications that fall within the meaning and scope of the claims.

In the above-described embodiment, there are two types of video signals input to the display device 1 and two types of specifications for the allowable power supply voltage, but there may be three or more types. For example, if there are four types of video signals input to the display device 1 and four types of specifications for the allowable power supply voltage, it is preferable to provide four input terminals for inputting video signals provided from outside the display device.

1, 1' Display device 11 Microcomputer 13 Display section 15 Detection section 15A First detection IC
15B Second detection IC
16A First Judgment IC
16B Second decision IC
P1 AD input port T1 First input terminal P2 Second input terminal

Claims (7)

A plurality of input terminals;
A display unit that displays an image based on an externally provided image signal;
a detection unit that detects to which of the plurality of input terminals the video signal is input;
a control unit that monitors a power supply voltage and turns off the display unit when the power supply voltage falls below a threshold;
Equipped with
The control unit switches the threshold value based on a detection result of the detection unit. The control unit includes a plurality of determination circuits each having a different threshold value, and a microcomputer that controls turning off the display unit,
each of the plurality of determination circuits monitors the power supply voltage and determines whether the power supply voltage falls below the threshold;
The display device according to claim 1 , wherein the microcomputer determines which of the determination results of the plurality of determination circuits to use based on the detection result of the detection unit. The control unit includes a microcomputer.
The power supply voltage is input to an AD input port of the microcomputer,
2. The display device according to claim 1, wherein the microcomputer performs AD conversion of the power supply voltage and monitors it. The control unit is
a determination circuit that monitors the power supply voltage and determines whether the power supply voltage has fallen below the threshold;
a microcomputer that turns off the display unit based on a result of the determination by the determination circuit;
Including,
The display device according to claim 1 , wherein the determination circuit is capable of switching the threshold value. The display device according to any one of claims 1 to 4, wherein the control unit sets the initial value of the threshold to the maximum value among the threshold switching candidates. A method for controlling a display device including a plurality of input terminals and a display unit that displays an image based on an externally provided image signal, comprising the steps of:
a detection step of detecting to which of the plurality of input terminals the video signal is input;
a step of monitoring a power supply voltage and turning off the display unit when the power supply voltage falls below a threshold;
Equipped with
The control method, wherein the turning off step includes a switching step of switching the threshold value based on a detection result of the detection step. The display device according to claim 1 , wherein the video signal provided from the outside is input to one of the plurality of input terminals determined depending on a type of vehicle in which the display device is mounted.

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