WO2017154691A1 - Display device - Google Patents

Display device Download PDF

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Publication number
WO2017154691A1
WO2017154691A1 PCT/JP2017/008054 JP2017008054W WO2017154691A1 WO 2017154691 A1 WO2017154691 A1 WO 2017154691A1 JP 2017008054 W JP2017008054 W JP 2017008054W WO 2017154691 A1 WO2017154691 A1 WO 2017154691A1
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WO
WIPO (PCT)
Prior art keywords
unit
emergency
signal
emergency information
video
Prior art date
Application number
PCT/JP2017/008054
Other languages
French (fr)
Japanese (ja)
Inventor
典昭 山口
Original Assignee
シャープ株式会社
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Publication date
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Publication of WO2017154691A1 publication Critical patent/WO2017154691A1/en

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    • G—PHYSICS
    • G02—OPTICS
    • G02F—OPTICAL DEVICES OR ARRANGEMENTS FOR THE CONTROL OF LIGHT BY MODIFICATION OF THE OPTICAL PROPERTIES OF THE MEDIA OF THE ELEMENTS INVOLVED THEREIN; NON-LINEAR OPTICS; FREQUENCY-CHANGING OF LIGHT; OPTICAL LOGIC ELEMENTS; OPTICAL ANALOGUE/DIGITAL CONVERTERS
    • G02F1/00—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics
    • G02F1/01—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour 
    • G02F1/13—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour  based on liquid crystals, e.g. single liquid crystal display cells
    • G02F1/133—Constructional arrangements; Operation of liquid crystal cells; Circuit arrangements
    • G—PHYSICS
    • G08—SIGNALLING
    • G08B—SIGNALLING OR CALLING SYSTEMS; ORDER TELEGRAPHS; ALARM SYSTEMS
    • G08B23/00—Alarms responsive to unspecified undesired or abnormal conditions
    • G—PHYSICS
    • G08—SIGNALLING
    • G08B—SIGNALLING OR CALLING SYSTEMS; ORDER TELEGRAPHS; ALARM SYSTEMS
    • G08B5/00—Visible signalling systems, e.g. personal calling systems, remote indication of seats occupied
    • G08B5/22—Visible signalling systems, e.g. personal calling systems, remote indication of seats occupied using electric transmission; using electromagnetic transmission
    • G08B5/36—Visible signalling systems, e.g. personal calling systems, remote indication of seats occupied using electric transmission; using electromagnetic transmission using visible light sources
    • G—PHYSICS
    • G09—EDUCATION; CRYPTOGRAPHY; DISPLAY; ADVERTISING; SEALS
    • G09G—ARRANGEMENTS OR CIRCUITS FOR CONTROL OF INDICATING DEVICES USING STATIC MEANS TO PRESENT VARIABLE INFORMATION
    • G09G3/00—Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes
    • G09G3/20—Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes for presentation of an assembly of a number of characters, e.g. a page, by composing the assembly by combination of individual elements arranged in a matrix no fixed position being assigned to or needed to be assigned to the individual characters or partial characters
    • G—PHYSICS
    • G09—EDUCATION; CRYPTOGRAPHY; DISPLAY; ADVERTISING; SEALS
    • G09G—ARRANGEMENTS OR CIRCUITS FOR CONTROL OF INDICATING DEVICES USING STATIC MEANS TO PRESENT VARIABLE INFORMATION
    • G09G3/00—Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes
    • G09G3/20—Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes for presentation of an assembly of a number of characters, e.g. a page, by composing the assembly by combination of individual elements arranged in a matrix no fixed position being assigned to or needed to be assigned to the individual characters or partial characters
    • G09G3/34—Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes for presentation of an assembly of a number of characters, e.g. a page, by composing the assembly by combination of individual elements arranged in a matrix no fixed position being assigned to or needed to be assigned to the individual characters or partial characters by control of light from an independent source
    • G—PHYSICS
    • G09—EDUCATION; CRYPTOGRAPHY; DISPLAY; ADVERTISING; SEALS
    • G09G—ARRANGEMENTS OR CIRCUITS FOR CONTROL OF INDICATING DEVICES USING STATIC MEANS TO PRESENT VARIABLE INFORMATION
    • G09G3/00—Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes
    • G09G3/20—Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes for presentation of an assembly of a number of characters, e.g. a page, by composing the assembly by combination of individual elements arranged in a matrix no fixed position being assigned to or needed to be assigned to the individual characters or partial characters
    • G09G3/34—Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes for presentation of an assembly of a number of characters, e.g. a page, by composing the assembly by combination of individual elements arranged in a matrix no fixed position being assigned to or needed to be assigned to the individual characters or partial characters by control of light from an independent source
    • G09G3/36—Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes for presentation of an assembly of a number of characters, e.g. a page, by composing the assembly by combination of individual elements arranged in a matrix no fixed position being assigned to or needed to be assigned to the individual characters or partial characters by control of light from an independent source using liquid crystals

Definitions

  • the present invention relates to a display device, and more particularly to a liquid crystal display device that can be used as a signage display.
  • a display device In recent years, it has become common to see display devices installed outdoors or in stores for the purpose of informing nearby people or passing people of guidance information and advertisements.
  • a display device is called a signage display, and a display device capable of displaying color images such as a liquid crystal display, a projector, a plasma display, and an LED display is used. Display as video.
  • the signage display not only displays the guidance information by specifying the time and place, but is also effectively used as an advertising medium such as a poster that does not require a lot of time and effort.
  • Patent Document 1 includes a power supply for power failure and a power source for power failure. By switching between these two power sources, an evacuation guidance display pattern with a long display time and a remarkable guidance effect is displayed during a power failure.
  • a guidance display device that performs useful guidance display other than evacuation guidance is disclosed. Furthermore, a liquid crystal display panel having a memory operation mode is used for the display panel of this guidance display device so that power is not consumed except when the display contents are rewritten.
  • Patent Document 1 discloses a chiral nematic liquid crystal display panel as a liquid crystal display panel having a memory operation mode.
  • a display device using a chiral nematic liquid crystal display panel as a reflective display is not suitable for displaying moving images because the response speed of liquid crystal is slow. Further, since the display brightness is not high, the visibility is low and it is not suitable for a signage display.
  • a backlight is required. Therefore, it is necessary to further secure a power supply for the backlight in order to continue displaying information on evacuation guidance during a power failure.
  • a first aspect of the present invention is an active matrix display device that displays video based on a video signal input from the outside, A display unit that displays the video; and a signal processing unit that processes the video signal and outputs the processed video signal to the display unit.
  • the display unit is A display panel in which a plurality of pixel circuits are arranged in a matrix; A drive circuit unit for driving the display panel; Including a light guide plate and a light emitting element attached to an end of the light guide plate, and comprising a backlight unit that irradiates the display panel with light emitted from the light emitting element as backlight light,
  • the signal processing unit If the video signal is given, a video processing unit that generates and outputs video data for displaying the video on the display panel; A timing control unit for outputting the video data and a control signal for controlling the drive circuit unit and the backlight unit to the drive circuit unit at a predetermined timing; A storage unit for storing emergency information data for displaying emergency information on the display panel; An emergency information detection unit that generate
  • the oxide semiconductor includes indium (In), gallium (Ga), zinc (Zn), and oxygen (O).
  • a battery circuit unit that enables power supply to the display unit and the signal processing unit by switching from the external power source when power supply from the external power source is stopped;
  • the emergency information detection unit is a power-off detection unit that outputs the emergency stop signal to the video processing unit and the battery circuit unit when detecting that the supply of power from the external power source is stopped.
  • the power-off detection unit outputs the emergency stop signal to the video processing unit and the battery circuit unit when it is determined that the cause of the power supply stop from the external power source is due to an abnormal cause
  • the battery circuit unit when given the emergency stop signal, supplies power to the video processing unit and the display unit
  • the video processing unit when given the emergency stop signal, stops the processing of the video signal, and outputs the emergency information data read from the storage unit to the drive circuit unit
  • the drive circuit writes a data voltage generated based on the emergency information data to the pixel circuit
  • the battery circuit unit may stop supplying power to the video processing unit and the display unit after the data voltage is written to the pixel circuit.
  • the drive circuit unit generates a data voltage having the same polarity based on the emergency information data, and writes the data voltage to the pixel circuit a plurality of times.
  • a sixth aspect of the present invention is the fourth aspect of the present invention.
  • the display panel is a normally white type liquid crystal display device.
  • the power-off detection unit supplies a power supply signal to the signal processing unit, the display unit, and the battery circuit unit.
  • the battery circuit unit supplies power to the signal processing unit and the display unit, and the signal processing unit and the display unit perform normal termination processing using power. It is characterized by that.
  • the emergency information detection unit is an emergency signal detection unit that outputs an emergency notification signal to the video processing unit when detecting that an emergency notification signal indicating an emergency situation has been input from the outside,
  • the video processing unit stops generating the video data and reads the emergency information data stored in the storage unit.
  • a data voltage based on the emergency information data is written to the pixel circuit every time after a pause period.
  • a ninth aspect of the present invention is the eighth aspect of the present invention.
  • the video processing unit when given the emergency stop signal, reads emergency information data from the storage unit for each pause period.
  • the light emitting elements of the backlight unit are a plurality of types of light emitting elements that emit different colors.
  • the backlight unit time-divides the plurality of types of light emitting elements for each subframe. And emitting light sequentially.
  • emergency information data representing emergency information is read from the storage unit and written to the pixel circuit of the display panel. Since the pixel circuit is formed with a thin film transistor having a channel layer made of an oxide semiconductor with a very small leakage current, the written emergency information data is held for a long time. Thereby, even if the power supply from the external power supply is stopped, emergency information can be notified to a person near the display device.
  • the oxide semiconductor constituting the channel layer of the thin film transistor contains indium, gallium, zinc, and oxygen, the leakage current can be extremely reduced. Thereby, the emergency information data written in the pixel circuit is held for a long time even after the supply of power is stopped, and the emergency information is continuously displayed.
  • the display device includes a battery circuit unit capable of supplying power.
  • the emergency information detection unit When the supply of power from the external power source is stopped, the emergency information detection unit outputs an emergency signal and switches the power source from the external power source to the battery circuit unit. Thereby, the emergency information data is written in the pixel circuit, and the display panel can continue to display the emergency information.
  • the power supply is switched from the external power supply to the battery circuit unit. Furthermore, using the power supplied from the battery circuit, the video processing unit writes the emergency information data read from the storage unit to the pixel circuit of the display panel, and then stops the power supply from the battery circuit unit. At this time, the backlight unit does not emit backlight light, but external light incident from the back side is irradiated on the display panel, and emergency information is displayed as a black and white image for a long time.
  • the battery circuit unit stops supplying power.
  • a liquid crystal burn-in phenomenon occurs in the pixel circuit, so that the written emergency information is retained for a longer time than in the case of the fourth invention, and the emergency information is displayed for a longer time.
  • the sixth aspect since no data voltage is applied to the pixel circuits other than the pixel circuit displaying the emergency information during emergency driving, if the display panel is a normally white type panel, the data voltage The pixel circuit to which no is applied becomes transparent, and the scenery on the back side of the liquid crystal display device can be seen through together with the emergency information. This makes it easier to determine the surrounding situation during a disaster and enables quick evacuation.
  • the power interruption detection unit determines that the cause of the stop of the supply of power from the external power supply is due to a normal cause
  • the power supply to the signal processing unit and the display unit is changed to the external power supply. Switch to the battery circuit to perform normal termination processing. Thereby, the display device can end the operation normally.
  • the video processing unit reads the emergency information data from the storage unit, and the pixel circuit of the display panel for each pause period by pause driving. Write to.
  • the display panel can continue to display the emergency information as a monochrome image.
  • the emergency information data is read from the storage unit for each pause period, so that different emergency information can be displayed on the display panel as a black and white video each time the pause period elapses.
  • a color image is displayed on each pixel circuit of the display panel.
  • the emitted light is not absorbed by the color filter and passes through the liquid crystal panel.
  • FIG. 1 is a block diagram illustrating a configuration of a liquid crystal display device according to a first embodiment of the present invention.
  • FIG. 2 is a diagram showing transistor characteristics of a TFT 28 whose channel layer is made of In—Ga—Zn—O in the liquid crystal display device shown in FIG.
  • FIG. 2 is a diagram showing backlight light emitted from a backlight unit in the liquid crystal display device shown in FIG. 1.
  • FIG. 2 is a diagram illustrating timings of writing data voltages generated based on video data and emergency information data in each of a normal drive mode and an emergency drive mode of the liquid crystal display device shown in FIG. 1.
  • FIG. 2 is a flowchart showing an interrupt routine for executing an interrupt process when power supply is stopped when the liquid crystal display device shown in FIG.
  • FIG. 1 displays an image in a normal drive mode.
  • FIG. 7 is a diagram illustrating timings of writing data voltages generated based on video data and emergency information data in each of a normal drive mode and an emergency drive mode of the liquid crystal display device shown in FIG. 6.
  • FIG. 7 is a flowchart showing an interrupt routine for performing an interrupt process when an emergency notification signal is input when the liquid crystal display device shown in FIG. 6 displays an image by normal driving. .
  • FIG. 1 is a block diagram showing the configuration of the liquid crystal display device according to the first embodiment of the present invention.
  • the liquid crystal display device includes a display unit 20, a signal processing unit 10 that drives the display unit 20, and a battery circuit unit 30 that supplies power SV2 to the signal processing unit 10 and the display unit 20 in the event of a power failure. It has.
  • the signal processing unit 10 includes a power-off detection unit 11, a video processing unit 12, a timing control unit 14, and a read only memory (ROM) 13.
  • the video processing unit 12 includes a video signal DAV output from an external video source 50 such as a personal computer (personal computer) installed outside the liquid crystal display device and a vertical synchronization signal necessary for displaying video.
  • a control signal SC1 such as a horizontal synchronization signal is input.
  • the power-off detection unit 11 may be referred to as an “emergency information detection unit”
  • the ROM 13 may be referred to as a “storage unit”.
  • the video processing unit 12 outputs the video data DV generated based on the video signal DAV given from the outside and the control signal SC1 to the timing control unit 14.
  • the timing controller 14 generates a data signal line drive circuit control signal Ssc and a scanning signal line drive circuit control signal Sgc based on the control signal SC1, and at a predetermined timing, the video data DV and the data signal line drive circuit
  • the control signal Ssc is output to the data signal line driving circuit 22 described later, and the scanning signal line driving circuit control signal Sgc is output to the scanning signal line driving circuit 23.
  • the display unit 20 includes a liquid crystal panel 21 that displays an image, a data signal line drive circuit 22 and a scanning signal line drive circuit 23 that drive the liquid crystal panel 21, and a backlight that emits backlight light from the back side of the liquid crystal panel 21.
  • Unit 24 At the end of the backlight unit 24, light emitting elements such as red (R), green (G), and blue (B) LEDs (Light Emitting Diode) and CCFL (Cathode Fluorescent Lamp) are attached.
  • the liquid crystal panel 21 may be referred to as a “display panel”.
  • Pixel circuits 27 are formed.
  • Each pixel circuit 27 has a thin film transistor 28 (Thin Film Transistor: TFT) having a gate electrode connected to the scanning signal line GL passing through the corresponding intersection and a source electrode connected to each data signal line SL passing through the intersection. ), A pixel electrode connected to the drain electrode of the TFT 28, a common electrode provided in common to the plurality of pixel circuits 27, and a liquid crystal layer sandwiched between the pixel electrode and the common electrode.
  • TFT Thin Film Transistor
  • the pixel electrode and the common electrode constitute a liquid crystal capacitor 29 together with the liquid crystal layer sandwiched between them.
  • the liquid crystal capacitor 29 holds a data voltage that is an analog signal generated based on the video data DV.
  • the liquid crystal sealed in the liquid crystal panel 21 may be a normally white type or a normally black type.
  • FIG. 1 shows only a pixel circuit 27 for one pixel, and a data signal line SL and a scanning signal line GL connected to the pixel circuit 27.
  • the data signal line drive circuit 22 operates a shift register and a sampling latch circuit (not shown) inside the data signal DV based on the video data DV in accordance with the control signal Ssc for the data signal line drive circuit.
  • a data voltage is generated by converting the data DV into an analog signal and applied to the data signal line SL.
  • the data signal line driver circuit control signal Ssc includes, for example, a source start pulse signal, a source clock signal, a latch strobe signal, and the like.
  • a plurality of data signal line driving circuits 22 are mounted on the substrate 22a, and the video data DV and the data signal line driving circuit control signal Ssc given from the timing control unit 14 are transmitted via the substrate 22a. The signal is supplied to each data signal line driving circuit 22.
  • the scanning signal line driving circuit 23 generates an active scanning signal by operating an internal shift register (not shown) in accordance with the scanning signal line driving circuit control signal Sgc, and outputs the scanning signal to each scanning signal line. It applies to GL in order.
  • the scanning signal line drive circuit control signal Sgc includes, for example, a gate clock signal and a gate start pulse signal.
  • a plurality of scanning signal line driving circuits 23 are mounted on the substrate 23a, and the scanning signal line driving circuit control signal Sgc given from the timing control unit 14 is sent to each scanning signal line via the substrate 23a. It is given to the drive circuit 23.
  • the data signal line drive circuit 22 and the scanning signal line drive circuit 23 may be collectively referred to as “drive circuit unit”.
  • the data voltage generated by the data signal line driving circuit 22 is written into the liquid crystal capacitor 29 of each pixel circuit 27 connected to the scanning signal line GL to which the active scanning signal is applied. Thereby, the transmittance of the liquid crystal layer of the pixel circuit 27 to which the data voltage is written is controlled, and the backlight light transmitted through the pixel circuit 27 changes. In this way, an image corresponding to the image data DV is displayed on the liquid crystal panel 21.
  • an oxide semiconductor particularly a semiconductor made of In—Ga—Zn—O (indium gallium zinc oxide) is used.
  • the channel layer of the TFT 28 is described as being composed of In—Ga—Zn—O.
  • the channel layer is not limited to In—Ga—Zn—O and includes other oxide semiconductors. Also good. Note that details of the TFT 28 including an oxide semiconductor in the channel layer will be described later.
  • the liquid crystal display device employs a field sequential method as a method for displaying a color image.
  • the red (R), green (G), and blue (B) LEDs 26r, 26g, and 25b attached to the end of the light guide plate 25 are sequentially switched in a time-sharing manner, and the liquid crystal is synchronized therewith.
  • color data corresponding to the light color of each light emitting element is sequentially given to the panel 21 to control its transmission state, and additive color mixing is performed on the retina of the observer.
  • color display is possible without forming a plurality of sub-pixel circuits in one pixel circuit 27, which is suitable for high resolution.
  • the emission color of the LED is not limited to a combination of red, green, and blue, and may be, for example, a combination of cyan, magenta, and yellow.
  • each component included in the signal processing unit 10 and the display unit 20 is operated by the electric power SV1 supplied from the external power supply 40.
  • the power interruption detection unit 11 provided in the signal processing unit 10 always monitors whether or not the electric power SV1 from the external power source 40 is supplied, and detects that the supply of the electric power SV1 from the external power source 40 has been stopped. Then, it is determined whether the power-off is an abnormal power-off or a normal power-off. Specifically, the power-off detection unit 11 is normal when a termination sequence started when a substrate provided in the signal processing unit 10 detects a signal, such as when an end button is pressed. If it is not, it is determined that the power supply is abnormal.
  • the video processing unit outputs an emergency stop signal Ses indicating that the supply of the power SV1 is stopped due to the abnormal power-off. 12 and the battery circuit unit 30.
  • the battery circuit unit 30 starts supplying the electric power SV2 to the signal processing unit 10 and the display unit 20 when an emergency stop signal Ses is given from the power-off detection unit 11. Thereby, the signal processing unit 10 and the display unit 20 become operable.
  • the video processing unit 12 When receiving the emergency stop signal Ses, the video processing unit 12 stops the processing of the video signal DAV supplied from the external video source 50 and its control signal SC1, and reads the emergency information data EMD stored in advance in the ROM 13.
  • the emergency information data EMD and the control signal Smsc generated based on the emergency information data EMD are output to the timing control unit 14.
  • the timing control unit 14 generates the control signals Smsc and Smgc necessary for displaying the emergency information, outputs the emergency information data EMD and the control signal Smsc to the data signal line driving circuit 22, and outputs the control signal Smgc to the scanning signal line. Output to the drive circuit 23.
  • the liquid crystal panel 21 of the display unit 20 uses the power SV2 supplied from the battery circuit unit 30 and the data voltage generated based on the emergency display data provided from the signal processing unit 10 is applied to each pixel circuit 27. Is written to.
  • the battery circuit unit 30 stops supplying the power SV2 to the signal processing unit 10 and the display unit 20.
  • the channel layer of the TFT 28 of the pixel circuit 27 includes an oxide semiconductor, the leakage current is very small even when the TFT 28 is turned off. For this reason, the written data voltage is continuously held in the pixel circuit 27 for a long time.
  • each of the red, green, and blue LEDs 26r, 26g, and 26b does not emit light.
  • external light incident on the liquid crystal panel 21 from the back side of the light guide plate 25 functions as backlight light.
  • the emergency information is displayed as a monochrome image.
  • the liquid crystal is a normally white type, when displaying emergency information on the liquid crystal panel 21, external light is emitted from the pixel circuit 27 where no emergency information is displayed, that is, the pixel circuit 27 where no data voltage is written. Since it is transmitted, the scenery on the back side of the liquid crystal display device can be seen through with the emergency information. This makes it easier to determine the surrounding situation during a disaster and enables quick evacuation.
  • the video processing unit 12 outputs a power supply signal Sps indicating that the supply of the power SV1 has been stopped for a normal reason. And output to the battery circuit unit 30.
  • the battery circuit unit 30 starts supplying the power SV2 to the signal processing unit 10 and the display unit 20. Thereby, the signal processing unit 10 and the display unit 20 become operable.
  • the video processing unit 12 When receiving the power supply signal Sps, the video processing unit 12 stops the processing of the video signal DAV supplied from the external video source 50 and its control signal SC1. Thereafter, the signal processing unit 10 and the display unit 20 each perform normal termination processing. Thus, when the normal termination process in the signal processing unit 10 and the display unit 20 is completed, the battery circuit unit 30 stops supplying the electric power SV2 to the signal processing unit 10 and the display unit 20.
  • FIG. 2 is a diagram showing the transistor characteristics of the TFT 28 whose channel layer is made of In—Ga—Zn—O.
  • the electrical characteristics of the TFT 28 are the same as those of an LTPS-TFT whose channel layer is made of low temperature poly silicon (LTPS) and an amorphous silicon TFT made of amorphous silicon. And will be described.
  • LTPS low temperature poly silicon
  • amorphous silicon TFT made of amorphous silicon.
  • the drain current Idd of the TFT 28 is larger than that of the amorphous silicon TFT. From this, it can be seen that the mobility of the TFT 28 is larger than that of the amorphous silicon TFT. Specifically, the mobility of the TFT 28 is 20 times greater than that of the amorphous silicon TFT. Therefore, the TFT 28 can be switched between the on state and the off state at a higher speed than the amorphous silicon TFT.
  • the drain current Idd when each TFT 28 is in an off state represents a leak current, and this value is preferably smaller.
  • the leakage current of the TFT 28 is significantly smaller than that of the LTPS-TFT and the amorphous silicon TFT. From this, it can be seen that when the TFT 28 is used as a switching element of the pixel circuit 27, the data voltage written in the pixel circuit 27 is held for a longer time than in the case of the LTPS-TFT or the amorphous silicon TFT.
  • the leakage current of the TFT 28 is as small as 1/1000 or less of the amorphous silicon TFT and 1/10000 or less of the LTPS-TFT.
  • the data voltage written in the pixel circuit 27 using the electric power SV2 supplied from the battery circuit unit 30 is the battery circuit unit 30. Even after the supply of the electric power SV2 from is stopped, it is held in the pixel circuit 27 for a long time, and emergency information can be displayed on the liquid crystal panel 21 for a long time.
  • FIG. 3 is a diagram showing backlight light emitted from the backlight unit 24.
  • the backlight light is different between the normal drive mode and the emergency drive mode.
  • the red LED 26r, the green LED 26g, and the blue LED 26b are lit in order in a time-sharing manner in each of the three sub-frames constituting one frame, thereby emitting red, green, and blue light in order.
  • red, green, and blue light are sequentially applied to the liquid crystal panel 21, and the liquid crystal panel 21 displays a color image corresponding to the video data DV.
  • FIG. 4 is a diagram illustrating timings of writing data voltages generated based on the video data DV and the emergency information data EMD in each of the normal drive mode and the emergency drive mode.
  • the normal drive mode field sequential drive is performed, so that the data voltage generated based on the video data DV to be displayed corresponds to the color of the backlight light to be emitted for each subframe.
  • the data voltage to be written is written in each pixel circuit 27. That is, the red LED 26r is turned on when the red data voltage is written, the green LED 26g is turned on when the green data voltage is written, and the blue LED 26b is turned on when the blue data voltage is written. Display video.
  • the data voltage generated based on the emergency information data EMD read from the ROM 13 is written to each pixel circuit 27 in the first one frame period.
  • all the LEDs 26r, 26g, and 26b are turned off, and the liquid crystal panel 21 is irradiated with external light incident from the back side. Therefore, the emergency information is displayed on the liquid crystal panel 21 as a black and white video.
  • FIG. 5 is a flowchart showing an interrupt routine for executing an interrupt process when the supply of power SV1 is stopped when the liquid crystal display device displays an image in the normal drive mode.
  • the liquid crystal display device displays a color image based on the video signal DAV supplied from the external video source 50 in the normal drive mode
  • a power interruption occurs in which the supply of the electric power SV1 supplied from the external power supply 40 is stopped.
  • the liquid crystal display device shifts from the normal drive mode to the emergency drive mode or the normal drive mode in accordance with the cause of the power cut-off, and displays the emergency information as a black and white image or performs a termination process. Therefore, referring to FIG. 5, the interrupt operation in the emergency drive mode and the normal end mode will be described as an interrupt routine.
  • step S ⁇ b> 10 when the power interruption detection unit 11 detects that a power interruption that stops the supply of the electric power SV ⁇ b> 1 from the external power supply 40 has occurred, it stops normal driving that has been performed so far. To do.
  • step S12 the power-off detector 11 determines whether the generated power-off is a normal power-off or an abnormal power-off. As a result, when it is determined that the power is turned off normally, the process proceeds to step S14 and shifts to the normal end mode. On the other hand, if it is determined that the power cut is an abnormal power cut, the process proceeds to step S22, which will be described later, and shifts to the emergency drive mode.
  • step S14 in order to supply the power SV2 to the signal processing unit 10 and the display unit 20, the power is turned off to the external power supply.
  • the battery circuit unit 30 is switched from 40. Therefore, the power-off detection unit 11 outputs the power supply signal Sps to the battery circuit unit 30.
  • the power source is switched to the battery circuit unit 30, and the electric power SV ⁇ b> 2 necessary for normal termination processing of the signal processing unit 10 and the display unit 20 is supplied to the signal processing unit 10 and the display unit 20.
  • step S16 the video processing unit 12 stops processing the video signal DAV and its control signal SC1.
  • step S ⁇ b> 18 normal termination processing is performed in the signal processing unit 10 and the display unit 20 by the electric power SV ⁇ b> 2 supplied from the battery circuit unit 30. As a result, the liquid crystal display device ends normally.
  • step S20 the supply of power SV2 from the battery circuit unit 30 to the signal processing unit 10 and the display unit 20 is stopped, and the interrupt routine is terminated.
  • step S22 when the power-off detection unit 11 determines in step S12 that the power-off is an abnormal power-off, in step S22, the power-off detection unit 11 supplies power SV2 to the signal processing unit 10 and the display unit 20. Switching from the external power supply 40 to the battery circuit unit 30 is performed. Therefore, the power interruption detection unit 11 outputs an emergency stop signal Ses to the battery circuit unit 30. As a result, electric power SV2 necessary for emergency driving is supplied to the signal processing unit 10 and the display unit 20.
  • step S24 the video processing unit 12 reads out from the ROM 13 emergency information data EMD to be displayed during emergency driving.
  • the read emergency information data EMD and the control signal SC ⁇ b> 2 generated based on the emergency information data EMD are output to the timing control unit 14.
  • a data voltage representing emergency information to be displayed in an emergency is output to the display unit at a predetermined timing to each pixel circuit 27 of the liquid crystal panel 21 and further written to each pixel circuit 27 of the liquid crystal panel 21.
  • step S28 the supply of power SV2 from the battery circuit unit 30 to the signal processing unit 10 and the display unit 20 is stopped. Even after the supply of the power SV2 is stopped, the pixel circuit 27 passes through the light guide plate 25 and enters from the back side until the voltage value of the data voltage written in the pixel circuit 27 is lowered to a predetermined value or less by the leak current. Transmit external light. As a result, the liquid crystal panel 21 continues to display black and white emergency information.
  • the pixel circuit 27 transmits the external light incident from the back side through the light guide plate 25.
  • the liquid crystal panel 21 can continue to display black and white emergency information, and can provide emergency information to surrounding people.
  • the liquid crystal panel 21 of the present embodiment since the color filter is not formed, the external light transmittance in the white display portion is increased, and the white display portion The brightness difference in the black display area increases. For this reason, it is possible to display an image with high visibility even under external light.
  • FIG. 6 is a block diagram showing a configuration of a liquid crystal display device according to the second embodiment of the present invention.
  • the liquid crystal display device includes a display unit 20 and a signal processing unit 10 for driving the display unit 20, but does not include a battery circuit unit.
  • the configuration of the display unit 20 is basically the same as the configuration of the block diagram shown in FIG. 1, but some components included in the signal processing unit 10 are different. Therefore, the same components are denoted by the same reference numerals, description thereof is omitted, and different components will be mainly described.
  • the liquid crystal display device also displays a color image corresponding to the video signal DAV supplied from the external video source 50 in the normal drive mode. Since the operation of the liquid crystal display device in the normal drive mode is the same as the operation described in the first embodiment, the description thereof is omitted.
  • the signal processing unit 10 includes an emergency signal detection unit 15 instead of the power-off detection unit 11 of the signal processing unit 10 illustrated in FIG. 1.
  • the emergency signal detection unit 15 outputs an emergency stop signal Ses to the video processing unit 12 when an emergency notification signal Sen notifying that an emergency has occurred is input from the outside.
  • the video processing unit 12 interrupts the processing of the video signal DAV supplied from the external video source 50 and its control signal SC1, reads out emergency information data EMD stored in advance in the ROM 13, The read emergency information data EMD and the control signal SC2 generated based on the emergency information data EMD are output to the timing control unit 14.
  • the emergency signal detection unit 15 may be referred to as an “emergency information detection unit”.
  • the timing control unit 14 outputs emergency information data EMD and its control signal SC2 to the display unit 20 in order to display emergency information on the liquid crystal panel 21 by performing pause driving.
  • the emergency information data EMD is written in each pixel circuit 27 of the liquid crystal panel 21.
  • the LEDs 26r, 26g, and 26b of the backlight unit 24 are turned off, so that external light is irradiated from the back side of the light guide plate 25 toward the liquid crystal panel 21.
  • the liquid crystal panel 21 displays the emergency information as a black and white image by pause driving that refreshes at a longer cycle than in normal driving.
  • the emergency information data EMD includes data capable of displaying only one still image and a plurality of data capable of displaying a plurality of still images.
  • the configuration of the TFT 28 provided in each pixel circuit 27 of the liquid crystal panel 21 of the present embodiment and the display of a color image by the field sequential method in the normal drive mode are the same as in the case of the first embodiment, Those descriptions are omitted.
  • the channel layer of the TFT 28 may not be In—Ga—Zn—O.
  • the written emergency information data EMD can be held for a long time, so that the suspension period can be made longer.
  • FIG. 7 is a diagram illustrating timings of writing data voltages generated based on the video data DV and the emergency information data EMD in each of the normal drive mode and the emergency drive mode. As shown in FIG. 7, the normal drive mode is the same as that shown in FIG.
  • the emergency information data EMD read from the ROM 13 is written in each pixel circuit 27 in the first frame period.
  • the LEDs 26r, 26g, and 26b are turned off, but since the external light is applied to the liquid crystal panel 21, the emergency information is displayed as a monochrome image.
  • the refresh is suspended for a predetermined period while the emergency information is displayed.
  • a predetermined pause period elapses, refresh is performed by writing the data voltage generated based on the emergency information data EMD to the pixel circuit 27 again.
  • the emergency information can be continuously displayed for a long time.
  • the emergency information data EMD is data that can display only one still image, the still image is repeatedly displayed.
  • the emergency information data EMD is data that can display a plurality of still images, different still images are displayed for each pause period.
  • FIG. 8 is a flowchart showing an interrupt routine for performing an interrupt process when the emergency notification signal Sen is input when the liquid crystal display device displays an image by normal driving.
  • the emergency notification signal Sen is suddenly input while the liquid crystal display device displays a color image by normal driving, the liquid crystal display device shifts from the normal driving mode to the emergency driving mode and displays emergency information.
  • the operation in the emergency drive mode will be described as an interrupt routine with reference to FIG.
  • step S40 the emergency signal detection unit 15 always monitors whether or not the emergency notification signal Sen is input.
  • the emergency notification signal Sen is detected, the emergency stop signal is sent to the video processing unit 12. Ses is output. Thereby, the video processing unit 12 can know that an emergency has occurred.
  • the video processing unit 12 When receiving the emergency stop signal Ses, the video processing unit 12 stops the processing of the video signal DAV supplied from the external video source 50 and the control signal SC1 in step S42, and shifts from the normal drive mode to the emergency drive mode. .
  • the emergency information data EMD is read from the ROM 13.
  • step S46 the video processing unit 12 generates the control signal SC2 based on the emergency information data EMD read from the ROM 13, and outputs the emergency information data EMD and the control signal SC2 to the display unit 20. Thereby, the data voltage generated from the emergency information data EMD is written in each pixel circuit 27 of the liquid crystal panel 21.
  • step S48 the process waits until the pause period of the pause drive elapses, and repeats returning to step S44 when the pause period elapses.
  • the liquid crystal panel 21 continues to display the emergency information as a black and white image for a long time by the external light that is transmitted through the light guide plate 25 and irradiated to the liquid crystal panel 21.
  • the emergency information data EMD read from the ROM 13 is data that can display only one still image, the still image is repeatedly displayed.
  • the emergency information data EMD is a plurality of data that can display a plurality of still images, a different still image is displayed for each pause period.
  • the video processing unit 12 reads the emergency information data EMD from the ROM 13, and the emergency information is sent to the pixel circuit 27 of the liquid crystal panel 21 for each pause period by pause driving. Write data.
  • the liquid crystal panel 21 can continue to display the emergency information as a monochrome image.
  • the liquid crystal panel 21 can continue to display black and white emergency information, and can provide emergency information to surrounding people.
  • the emergency information includes information displayed by one still image that is repeatedly displayed, and information that sequentially displays a plurality of still images, and the liquid crystal display device displays information according to an emergency situation. Information to be selected is appropriately selected and displayed.
  • the normal drive described in the first embodiment is stopped after the supply of the electric power SV1 from the external power supply 40 is terminated due to an abnormal interruption.
  • the mode is shifted to the drive mode, and data voltages having the same polarity are continuously applied in a plurality of frames immediately after that.
  • image sticking occurs in the pixel circuit 27 to which the data voltage of the same polarity has been continuously applied, and a black and white image representing emergency information is displayed for a longer time than in the first embodiment.
  • the configuration of the liquid crystal display device according to the third embodiment of the present invention is the same as that of the liquid crystal display device shown in FIG. 1, a block diagram showing the configuration and description thereof are omitted. Further, since the configuration of the TFT 28 provided in the pixel circuit 27 and the driving of the backlight unit 24 by the field sequential method in the normal driving mode are the same as those in the first embodiment, the description thereof is omitted.
  • FIG. 9 is a diagram showing the write timing of data voltages to be written to the pixel circuit 27 based on the video data DV and the emergency information data EMD in the normal drive mode and the emergency drive mode in the present embodiment.
  • the operation in the normal drive mode is the same as the operation described in the first embodiment, and a detailed description thereof is omitted.
  • the polarity of the data voltage applied to the pixel circuit 27 is set to a subframe. The occurrence of image sticking is prevented by reversing each time.
  • the backlight unit 24 is driven by a field sequential method to display a color image.
  • the power-off detector 11 detects that an abnormal interruption has occurred. In this case, as described in the first embodiment, the power-off detection unit 11 switches the power source from the external power source 40 to the battery circuit unit 30 and switches the drive mode from the normal drive mode to the emergency display mode.
  • the video processing unit 12 reads the emergency information data EMD stored in advance in the ROM 13 to generate the control signal SC2, and outputs the emergency information data EMD and the control signal SC2 to the display unit 20, thereby A data voltage having the same polarity is repeatedly applied to the pixel circuit 27 over a period of several frames immediately after switching to the display mode. That is, as shown in FIG. 9, for example, data voltages having the same polarity (all positive in FIG. 9) are applied to the pixel circuit 27 in each frame period. Thereafter, the supply of the electric power SV2 from the battery circuit unit 30 is stopped while the data voltage is held.
  • the oxide semiconductor contained in the channel layer of the TFT 28 may be an amorphous oxide semiconductor or a crystalline oxide semiconductor having a crystalline portion.
  • a crystalline oxide semiconductor a polycrystalline oxide semiconductor, a microcrystalline oxide semiconductor, a crystalline oxide semiconductor in which the c-axis is oriented substantially perpendicular to the layer surface, or the like can be used.
  • the channel layer of the TFT 28 may be a laminated film of two or more layers.
  • the channel layer may include an amorphous oxide semiconductor and a crystalline oxide semiconductor, may include a plurality of crystalline oxide semiconductors having different crystal structures, and a plurality of amorphous An oxide semiconductor may be included.
  • the energy gap of the oxide semiconductor included in the upper layer is preferably larger than the energy gap of the oxide semiconductor included in the lower layer.
  • the energy gap of the lower oxide semiconductor may be larger than the energy gap of the upper oxide semiconductor.
  • the oxide semiconductor may contain, for example, at least one metal element of In, Ga, and Zn.
  • the oxide semiconductor include an In—Ga—Zn—O-based semiconductor.
  • the In—Ga—Zn—O-based semiconductor is a ternary oxide of In (indium), Ga (gallium), and Zn (zinc).
  • the channel layer is formed using an oxide semiconductor including an In—Ga—Zn—O-based semiconductor.
  • the In—Ga—Zn—O-based semiconductor may be amorphous or crystalline.
  • a crystalline In—Ga—Zn—O-based semiconductor in which the c-axis is oriented substantially perpendicular to the layer surface is preferable.
  • a TFT having an In—Ga—Zn—O-based semiconductor layer exhibits high mobility (more than 20 times that of an amorphous silicon TFT) and low leakage current (less than 100 times that of an amorphous silicon TFT).
  • a TFT having an In—Ga—Zn—O-based semiconductor layer includes a scanning signal line driving circuit 23 provided on the same substrate as the liquid crystal panel 21 around the liquid crystal panel 21 including the plurality of pixel circuits 27.
  • the TFT is preferably used as a TFT included in the data signal line driving circuit 22 and a TFT 28 provided in the pixel circuit 27.
  • the channel layer may contain another oxide semiconductor instead of the In—Ga—Zn—O-based semiconductor.
  • the channel layer may include, for example, an In—Sn—Zn—O-based semiconductor (eg, In 2 O 3 —SnO 2 —ZnO; InSnZnO).
  • the In—Sn—Zn—O-based semiconductor is a ternary oxide of In (indium), Sn (tin), and Zn (zinc).
  • the channel layer includes an In—Al—Zn—O based semiconductor, an In—Al—Sn—Zn—O based semiconductor, a Zn—O based semiconductor, an In—Zn—O based semiconductor, a Zn—Ti—O based semiconductor, Cd—Ge—O based semiconductor, Cd—Pb—O based semiconductor, CdO (cadmium oxide), Mg—Zn—O based semiconductor, In—Ga—Sn—O based semiconductor, In—Ga—O based semiconductor, Zr— An In—Zn—O based semiconductor, an Hf—In—Zn—O based semiconductor, or the like may be included.
  • Al represents aluminum
  • Ti represents titanium
  • Cd represents cadmium
  • Ge germanium
  • Pb represents lead
  • Mg represents magnesium
  • Zr zirconium
  • Hf hafnium.

Abstract

The present invention provides a display device with which it is possible to display useful information in an easily readable manner at a time of normal drive and display emergency information continuously for a long time at a time of emergency drive that is exercised in case of emergency. When the supply of power being supplied from an external power source (40) is stopped, emergency information data EMD is read out from a ROM (13) and written into a pixel circuit (27). Because a TFT (28) having a channel layer comprising an oxide semiconductor of which the leakage current is very small is formed in the pixel circuit (27), the written emergency information data EMD is held over a long time even when the supply of power SV2 from a battery circuit unit (30) is stopped. Thus, even when the supply of electricity from the external power source (40) is stopped, emergency information can be issued to persons present in the vicinity of the display device.

Description

表示装置Display device
　本発明は、表示装置に関し、特に、サイネージディスプレイとして利用可能な液晶表示装置に関する。 The present invention relates to a display device, and more particularly to a liquid crystal display device that can be used as a signage display.
　近年、近くにいる人や通りすがりの人に案内情報や広告などを知らせることを目的として、屋外や店頭などに設置されている表示装置を見かけることが多くなった。このような表示装置はサイネージディスプレイと呼ばれ、液晶ディスプレイ、プロジェクタ、プラズマディスプレイ、ＬＥＤディスプレイなどのカラー映像を表示することが可能な表示装置が使用されており、インターネットによって配信された映像情報をカラー映像として表示する。このように、サイネージディスプレイは、時間と場所を特定して案内情報を表示するだけでなく、ポスターのように貼り替えの手間がかからない広告媒体としても有効に活用されている。 In recent years, it has become common to see display devices installed outdoors or in stores for the purpose of informing nearby people or passing people of guidance information and advertisements. Such a display device is called a signage display, and a display device capable of displaying color images such as a liquid crystal display, a projector, a plasma display, and an LED display is used. Display as video. As described above, the signage display not only displays the guidance information by specifying the time and place, but is also effectively used as an advertising medium such as a poster that does not require a lot of time and effort.
　また、特許文献１には、停電用電源と通常用電源とを備え、これら２つの電源を切り換えることにより、停電時には表示時間が長く、誘導効果も顕著な避難誘導表示パターンを表示し、通常時には避難誘導以外の有用な案内表示を行う誘導表示装置が開示されている。さらに、この誘導表示装置の表示パネルには、表示内容を書き換えるとき以外には電力を消費しないように、メモリ性の動作モードを有する液晶表示パネルが用いられている。 Further, Patent Document 1 includes a power supply for power failure and a power source for power failure. By switching between these two power sources, an evacuation guidance display pattern with a long display time and a remarkable guidance effect is displayed during a power failure. A guidance display device that performs useful guidance display other than evacuation guidance is disclosed. Furthermore, a liquid crystal display panel having a memory operation mode is used for the display panel of this guidance display device so that power is not consumed except when the display contents are rewritten.
日本の特開２００４－２０６５０３号公報Japanese Unexamined Patent Publication No. 2004-206503
　特許文献１には、メモリ性の動作モードを有する液晶表示パネルとして、カイラルネマチック液晶表示パネルが開示されている。しかし、カイラルネマチック液晶表示パネルを反射型ディスプレイとして使用した表示装置は、液晶の応答速度が遅いので、動画表示には適していない。また、表示輝度が高くないので、視認性が低く、サイネージディスプレイにも適していない。一方、透過型ディスプレイとして使用した場合には、バックライトが必要になるので、停電時に避難誘導の情報を表示し続けるためにバックライト用の電源をさらに確保する必要がある。 Patent Document 1 discloses a chiral nematic liquid crystal display panel as a liquid crystal display panel having a memory operation mode. However, a display device using a chiral nematic liquid crystal display panel as a reflective display is not suitable for displaying moving images because the response speed of liquid crystal is slow. Further, since the display brightness is not high, the visibility is low and it is not suitable for a signage display. On the other hand, when it is used as a transmissive display, a backlight is required. Therefore, it is necessary to further secure a power supply for the backlight in order to continue displaying information on evacuation guidance during a power failure.
　そこで、通常駆動時には有用な情報を見やすく表示すると共に、緊急事態が発生したときに行う緊急駆動時には緊急情報を長時間表示し続けることが可能な表示装置を提供することを目的とする。 Therefore, it is an object of the present invention to provide a display device capable of displaying useful information in an easy-to-see manner during normal driving and capable of continuously displaying emergency information for a long time during emergency driving performed when an emergency situation occurs.
　本発明の第１の局面は、外部から入力された映像信号に基づき映像を表示するアクティブマトリクス型の表示装置であって、
　前記映像を表示するディスプレイ部と、前記映像信号を処理して前記ディスプレイ部に出力する信号処理部とを備え、
　前記ディスプレイ部は、
　　複数の画素回路がマトリクス状に配置された表示パネルと、
　　前記表示パネルを駆動する駆動回路部と、
　　導光板と、前記導光板の端部に取り付けられた発光素子とを含み、前記発光素子から出射された光をバックライト光として前記表示パネルに照射するバックライトユニットとを備え、
　前記信号処理部は、
　　前記映像信号を与えられれば、前記表示パネルに前記映像を表示するための映像データを生成して出力する映像処理部と、
　　前記映像データと、前記駆動回路部および前記バックライトユニットを制御する制御信号とを所定のタイミングで前記駆動回路部に出力するタイミング制御部と、
　　緊急情報を前記表示パネルに表示するための緊急情報データを格納する記憶部と、
　　緊急情報を検知したとき緊急停止信号を生成して、少なくとも前記映像処理部に出力する緊急情報検知部とを備え、
　前記画素回路のスイッチング素子は、チャネル層に酸化物半導体を含む薄膜トランジスタであり、
　前記映像処理部は、前記緊急情報検知部から前記緊急停止信号を与えられると、前記映像データの生成を停止し、前記記憶部に格納されている緊急情報データを読み出して前記駆動回路部に出力することにより、前記表示パネルに前記緊急情報を表示し、前記バックライトユニットは、前記発光素子を消灯させることを特徴とする。 A first aspect of the present invention is an active matrix display device that displays video based on a video signal input from the outside,
A display unit that displays the video; and a signal processing unit that processes the video signal and outputs the processed video signal to the display unit.
The display unit is
A display panel in which a plurality of pixel circuits are arranged in a matrix;
A drive circuit unit for driving the display panel;
Including a light guide plate and a light emitting element attached to an end of the light guide plate, and comprising a backlight unit that irradiates the display panel with light emitted from the light emitting element as backlight light,
The signal processing unit
If the video signal is given, a video processing unit that generates and outputs video data for displaying the video on the display panel;
A timing control unit for outputting the video data and a control signal for controlling the drive circuit unit and the backlight unit to the drive circuit unit at a predetermined timing;
A storage unit for storing emergency information data for displaying emergency information on the display panel;
An emergency information detection unit that generates an emergency stop signal when emergency information is detected and outputs the emergency stop signal to at least the video processing unit;
The switching element of the pixel circuit is a thin film transistor including an oxide semiconductor in a channel layer,
When the emergency stop signal is given from the emergency information detection unit, the video processing unit stops generating the video data, reads the emergency information data stored in the storage unit, and outputs the emergency information data to the drive circuit unit Thus, the emergency information is displayed on the display panel, and the backlight unit turns off the light emitting element.
　本発明の第２の局面は、本発明の第１の局面において、
　前記酸化物半導体は、インジウム（Ｉｎ）、ガリウム（Ｇａ），亜鉛（Ｚｎ）、酸素（Ｏ）を含むことを特徴とする。 According to a second aspect of the present invention, in the first aspect of the present invention,
The oxide semiconductor includes indium (In), gallium (Ga), zinc (Zn), and oxygen (O).
　本発明の第３の局面は、本発明の第１の局面において、
　外部電源からの電力の供給が停止されたときに、前記外部電源から切り換えることによって前記ディスプレイ部および前記信号処理部に電力の供給を可能にするバッテリ回路部をさらに備え、
　前記緊急情報検知部は、前記外部電源からの電力の供給が停止したことを検知したとき、前記映像処理部と前記バッテリ回路部とに前記緊急停止信号を出力する電源断検知部であることを特徴とする。 According to a third aspect of the present invention, in the first aspect of the present invention,
A battery circuit unit that enables power supply to the display unit and the signal processing unit by switching from the external power source when power supply from the external power source is stopped;
The emergency information detection unit is a power-off detection unit that outputs the emergency stop signal to the video processing unit and the battery circuit unit when detecting that the supply of power from the external power source is stopped. Features.
　本発明の第４の局面は、本発明の第３の局面において、
　前記電源断検知部は、前記外部電源からの電力の供給停止原因が異常な原因によるものと判定した場合には、前記映像処理部と前記バッテリ回路部とに前記緊急停止信号を出力し、
　前記バッテリ回路部は、前記緊急停止信号を与えられると、前記映像処理部と前記ディスプレイ部とに電力を供給し、
　前記映像処理部は、前記緊急停止信号を与えられると、前記映像信号の処理を停止して、前記記憶部から読み出した前記緊急情報データを前記駆動回路部に出力し、
　前記駆動回路は、前記緊急情報データに基づいて生成したデータ電圧を前記画素回路に書き込み、
　前記バッテリ回路部は、前記データ電圧が前記画素回路に書き込まれた後に、前記映像処理部と前記ディスプレイ部への電力の供給を停止することを特徴とする。 According to a fourth aspect of the present invention, in the third aspect of the present invention,
The power-off detection unit outputs the emergency stop signal to the video processing unit and the battery circuit unit when it is determined that the cause of the power supply stop from the external power source is due to an abnormal cause,
The battery circuit unit, when given the emergency stop signal, supplies power to the video processing unit and the display unit,
The video processing unit, when given the emergency stop signal, stops the processing of the video signal, and outputs the emergency information data read from the storage unit to the drive circuit unit,
The drive circuit writes a data voltage generated based on the emergency information data to the pixel circuit,
The battery circuit unit may stop supplying power to the video processing unit and the display unit after the data voltage is written to the pixel circuit.
　本発明の第５の局面は、本発明の第４の局面において、
　前記駆動回路部は、前記緊急情報データに基づいて同一極性のデータ電圧を生成し、前記画素回路に複数回書き込むことを特徴とする。 According to a fifth aspect of the present invention, in the fourth aspect of the present invention,
The drive circuit unit generates a data voltage having the same polarity based on the emergency information data, and writes the data voltage to the pixel circuit a plurality of times.
　本発明の第６の局面は、本発明の第４の局面において、
　前記表示パネルは、ノーマリホワイトタイプの液晶表示装置であることを特徴とする。 A sixth aspect of the present invention is the fourth aspect of the present invention,
The display panel is a normally white type liquid crystal display device.
　本発明の第７の局面は、本発明の第３の局面において、
　前記電源断検知部は、前記外部電源からの電力の供給停止原因が正常な原因によるものと判定した場合には、前記信号処理部と、前記ディスプレイ部と、前記バッテリ回路部とに電力供給信号を出力し、
　前記バッテリ回路部は、前記電力供給信号を与えられると、前記信号処理部と前記ディスプレイ部に電力を供給し、前記信号処理部およびと前記ディスプレイ部は、電力を使用して正常終了処理を行うことを特徴とする。 According to a seventh aspect of the present invention, in the third aspect of the present invention,
When it is determined that the cause of the power supply stop from the external power supply is due to a normal cause, the power-off detection unit supplies a power supply signal to the signal processing unit, the display unit, and the battery circuit unit. Output
When the power supply signal is given, the battery circuit unit supplies power to the signal processing unit and the display unit, and the signal processing unit and the display unit perform normal termination processing using power. It is characterized by that.
　本発明の第８の局面は、本発明の第１の局面において、
　前記緊急情報検知部は、外部から緊急事態を示す緊急通知信号が入力されたことを検知したとき、前記映像処理部に緊急通知信号を出力する緊急信号検知部であり、
　前記映像処理部は、前記緊急通知信号を与えられると、前記映像データの生成を停止して前記記憶部に格納されている緊急情報データを読み出し、前記駆動回路部は、前記タイミング制御部は、前記緊急情報データに基づくデータ電圧を休止期間の経過後毎に前記画素回路に書き込むことを特徴とする。 According to an eighth aspect of the present invention, in the first aspect of the present invention,
The emergency information detection unit is an emergency signal detection unit that outputs an emergency notification signal to the video processing unit when detecting that an emergency notification signal indicating an emergency situation has been input from the outside,
When the video processing unit is given the emergency notification signal, the video processing unit stops generating the video data and reads the emergency information data stored in the storage unit. A data voltage based on the emergency information data is written to the pixel circuit every time after a pause period.
　本発明の第９の局面は、本発明の第８の局面において、
　前記映像処理部は、前記緊急停止信号を与えられると、前記休止期間毎に前記記憶部から緊急情報データを読み出すことを特徴とする。 A ninth aspect of the present invention is the eighth aspect of the present invention,
The video processing unit, when given the emergency stop signal, reads emergency information data from the storage unit for each pause period.
　本発明の第１０の局面は、本発明の第１の局面において、
　前記バックライトユニットの前記発光素子は、異なる色を発光する複数種類の発光素子であり、前記映像を表示する通常駆動時には、前記バックライトユニットは前記複数種類の発光素子をサブフレーム毎に時分割して順に発光させることを特徴とする。 According to a tenth aspect of the present invention, in the first aspect of the present invention,
The light emitting elements of the backlight unit are a plurality of types of light emitting elements that emit different colors. During normal driving for displaying the video, the backlight unit time-divides the plurality of types of light emitting elements for each subframe. And emitting light sequentially.
　上記第１の局面によれば、外部電源から供給されていた電力の供給が停止されたとき、緊急情報を表す緊急情報データを記憶部から読み出して表示パネルの画素回路に書き込む。画素回路には、リーク電流が非常に小さい酸化物半導体からなるチャネル層を有する薄膜トランジスタが形成されているので、書き込まれた緊急情報データは長時間に渡って保持される。これにより、外部電源からの給電が停止されても、表示装置の近くにいる人に緊急情報を知らせることができる。 According to the first aspect, when the supply of power supplied from the external power supply is stopped, emergency information data representing emergency information is read from the storage unit and written to the pixel circuit of the display panel. Since the pixel circuit is formed with a thin film transistor having a channel layer made of an oxide semiconductor with a very small leakage current, the written emergency information data is held for a long time. Thereby, even if the power supply from the external power supply is stopped, emergency information can be notified to a person near the display device.
　上記第２の局面によれば、薄膜トランジスタのチャネル層を構成する酸化物半導体は、インジウム、ガリウム、亜鉛、酸素を含むので、リーク電流を非常に小さくすることができる。これにより、画素回路に書き込まれた緊急情報データは、電力の供給が停止された後も長時間に渡って保持され、緊急情報を表示し続ける。 According to the second aspect, since the oxide semiconductor constituting the channel layer of the thin film transistor contains indium, gallium, zinc, and oxygen, the leakage current can be extremely reduced. Thereby, the emergency information data written in the pixel circuit is held for a long time even after the supply of power is stopped, and the emergency information is continuously displayed.
　上記第３の局面によれば、表示装置は電力の供給が可能なバッテリ回路部を備えている。外部電源からの電力の供給が停止されたとき、緊急情報検知部は緊急事態信号を出力し、電源を外部電源からバッテリ回路部に切り換える。これにより、緊急情報データが画素回路に書き込まれ、表示パネルは緊急情報を表示し続けることができる。 According to the third aspect, the display device includes a battery circuit unit capable of supplying power. When the supply of power from the external power source is stopped, the emergency information detection unit outputs an emergency signal and switches the power source from the external power source to the battery circuit unit. Thereby, the emergency information data is written in the pixel circuit, and the display panel can continue to display the emergency information.
　上記第４の局面によれば、外部電源からの電力の供給が停止されたとき、その供給停止原因が異常な原因によるものと判定した場合には、電源を外部電源からバッテリ回路部に切り換える。さらに、バッテリ回路から供給される電力を使用して、映像処理部が記憶部から読み出した緊急情報データを表示パネルの画素回路に書き込み、その後バッテリ回路部からの電力の供給を停止する。このとき、バックライトユニットはバックライト光を出射しないが、背面側から入射する外光が表示パネルに照射され、緊急情報が白黒映像で長時間表示される。 According to the fourth aspect, when the supply of power from the external power supply is stopped, if it is determined that the cause of the supply stop is due to an abnormal cause, the power supply is switched from the external power supply to the battery circuit unit. Furthermore, using the power supplied from the battery circuit, the video processing unit writes the emergency information data read from the storage unit to the pixel circuit of the display panel, and then stops the power supply from the battery circuit unit. At this time, the backlight unit does not emit backlight light, but external light incident from the back side is irradiated on the display panel, and emergency information is displayed as a black and white image for a long time.
　上記第５の局面によれば、緊急情報データに基づいて生成した同一極性のデータ電圧を画素回路に複数回書き込んだ後に、バッテリ回路部は電力の供給を停止する。これにより、画素回路では液晶の焼き付き現象が発生するので、書き込まれた緊急情報は第４の発明の場合よりも長時間に渡って保持され、緊急情報がより長時間表示される。 According to the fifth aspect, after the data voltage having the same polarity generated based on the emergency information data is written to the pixel circuit a plurality of times, the battery circuit unit stops supplying power. As a result, a liquid crystal burn-in phenomenon occurs in the pixel circuit, so that the written emergency information is retained for a longer time than in the case of the fourth invention, and the emergency information is displayed for a longer time.
　上記第６の局面によれば、緊急駆動時に、緊急情報が表示されている画素回路以外の画素回路にはデータ電圧が印加されないので、表示パネルをノーマリホワイトタイプのパネルにすれば、データ電圧が印加されていない画素回路は透明になり、緊急情報と共に液晶表示装置の背面側の風景が透けて見える。これにより、災害時には周囲の状況を判断しやすくなり、迅速な避難が可能になる。 According to the sixth aspect, since no data voltage is applied to the pixel circuits other than the pixel circuit displaying the emergency information during emergency driving, if the display panel is a normally white type panel, the data voltage The pixel circuit to which no is applied becomes transparent, and the scenery on the back side of the liquid crystal display device can be seen through together with the emergency information. This makes it easier to determine the surrounding situation during a disaster and enables quick evacuation.
　上記第７の局面によれば、電源断検知部によって、外部電源からの電力の供給停止原因が正常な原因によるものと判断されれば、信号処理部およびディスプレイ部への電力の供給を外部電源からバッテリ回路部に切り換え、正常終了処理を行う。これにより、表示装置は動作を正常に終了することができる。 According to the seventh aspect, if the power interruption detection unit determines that the cause of the stop of the supply of power from the external power supply is due to a normal cause, the power supply to the signal processing unit and the display unit is changed to the external power supply. Switch to the battery circuit to perform normal termination processing. Thereby, the display device can end the operation normally.
　上記第８の局面によれば、外部から緊急信号検知部に緊急通知信号が入力されれば、映像処理部は記憶部から緊急情報データを読み出し、休止駆動によって休止期間毎に表示パネルの画素回路に書き込む。このとき、信号処理部およびディスプレイ部には外部電源から電力が供給され続けているので、表示パネルは、緊急情報を白黒の映像として表示し続けることができる。 According to the eighth aspect, when an emergency notification signal is input from the outside to the emergency signal detection unit, the video processing unit reads the emergency information data from the storage unit, and the pixel circuit of the display panel for each pause period by pause driving. Write to. At this time, since the power is continuously supplied from the external power source to the signal processing unit and the display unit, the display panel can continue to display the emergency information as a monochrome image.
　上記第９の局面によれば、休止期間毎に記憶部から緊急情報データを読み出すので、休止期間が経過する毎に、表示パネルに異なる緊急情報を白黒の映像として表示することができる。 According to the ninth aspect, the emergency information data is read from the storage unit for each pause period, so that different emergency information can be displayed on the display panel as a black and white video each time the pause period elapses.
　上記第１０の局面によれば、通常駆動時には、異なる色の光を出射する複数種類の発光素子が配置されたバックライトユニットから出射された異なる色の光が時分割で順に表示パネルに照射される。これにより、表示パネルの各画素回路にカラー映像が表示される。この場合、カラーフィルタは形成されないので、出射された光はカラーフィルタに吸収されることがなく液晶パネルを透過する。また、カラーフィルタを形成する際に形成される複数の副画素回路を形成する必要もない。これにより、高輝度のカラー映像を高解像度で表示することができる。 According to the tenth aspect, during normal driving, light of different colors emitted from a backlight unit in which a plurality of types of light emitting elements that emit light of different colors is arranged is sequentially irradiated onto the display panel in a time-sharing manner. The As a result, a color image is displayed on each pixel circuit of the display panel. In this case, since a color filter is not formed, the emitted light is not absorbed by the color filter and passes through the liquid crystal panel. Further, it is not necessary to form a plurality of subpixel circuits formed when forming the color filter. Thereby, a high-luminance color image can be displayed with high resolution.
本発明の第１の実施形態に係る液晶表示装置の構成を示すブロック図である。1 is a block diagram illustrating a configuration of a liquid crystal display device according to a first embodiment of the present invention. 図１に示す液晶表示装置において、チャネル層がＩｎ－Ｇａ－Ｚｎ－ＯからなるＴＦＴ２８のトランジスタ特性を示す図である。FIG. 2 is a diagram showing transistor characteristics of a TFT 28 whose channel layer is made of In—Ga—Zn—O in the liquid crystal display device shown in FIG. 図１に示す液晶表示装置において、バックライトユニットから出射されるバックライト光を示す図である。FIG. 2 is a diagram showing backlight light emitted from a backlight unit in the liquid crystal display device shown in FIG. 1. 図１に示す液晶表示装置の通常駆動モードおよび緊急駆動モードのそれぞれにおいて、映像データおよび緊急情報データに基づいて生成されたそれぞれのデータ電圧を書き込むタイミングを示す図である。FIG. 2 is a diagram illustrating timings of writing data voltages generated based on video data and emergency information data in each of a normal drive mode and an emergency drive mode of the liquid crystal display device shown in FIG. 1. 図１に示す液晶表示装置が通常駆動モードによって映像を表示しているときに、電力の供給が停止されたことによる割込処理を実行するための割込ルーチンを示すフロー図である。FIG. 2 is a flowchart showing an interrupt routine for executing an interrupt process when power supply is stopped when the liquid crystal display device shown in FIG. 1 displays an image in a normal drive mode. 本発明の第２の実施形態に係る液晶表示装置の構成を示すブロック図である。It is a block diagram which shows the structure of the liquid crystal display device which concerns on the 2nd Embodiment of this invention. 図６に示す液晶表示装置の通常駆動モードおよび緊急駆動モードのそれぞれにおいて、映像データおよび緊急情報データに基づいて生成されたそれぞれのデータ電圧を書き込むタイミングを示す図である。FIG. 7 is a diagram illustrating timings of writing data voltages generated based on video data and emergency information data in each of a normal drive mode and an emergency drive mode of the liquid crystal display device shown in FIG. 6. 図６に示す液晶表示装置において、液晶表示装置が通常駆動によって映像を表示しているときに、緊急通知信号が入力されたことによる割込処理をするための割込ルーチンを示すフロー図である。FIG. 7 is a flowchart showing an interrupt routine for performing an interrupt process when an emergency notification signal is input when the liquid crystal display device shown in FIG. 6 displays an image by normal driving. . 本発明の第３の実施形態にかかる液晶表示装置の通常駆動モードと緊急駆動モードにおいて、映像データおよび緊急情報データに基づいて画素回路にそれぞれ書き込むべきデータ電圧の書込みタイミングを示す図である。It is a figure which shows the write-in timing of the data voltage which should each be written in a pixel circuit based on video data and emergency information data in the normal drive mode and emergency drive mode of the liquid crystal display device concerning the 3rd Embodiment of this invention.
＜１．第１の実施形態＞
＜１．１　液晶表示装置の構成および動作概要＞
　図１は、本発明の第１の実施形態に係る液晶表示装置の構成を示すブロック図である。図１に示すように、液晶表示装置は、ディスプレイ部２０と、ディスプレイ部２０を駆動する信号処理部１０と、停電時に信号処理部１０およびディスプレイ部２０に電力ＳＶ２を供給するバッテリ回路部３０とを備えている。 <1. First Embodiment>
<1.1 Configuration and operation overview of liquid crystal display device>
FIG. 1 is a block diagram showing the configuration of the liquid crystal display device according to the first embodiment of the present invention. As shown in FIG. 1, the liquid crystal display device includes a display unit 20, a signal processing unit 10 that drives the display unit 20, and a battery circuit unit 30 that supplies power SV2 to the signal processing unit 10 and the display unit 20 in the event of a power failure. It has.
　まず、液晶表示装置の通常時における動作（通常駆動モード）について説明する。信号処理部１０は、電源断検知部１１、映像処理部１２、タイミング制御部１４、および読出専用メモリ（read only memory：ＲＯＭ）１３を含む。映像処理部１２には、液晶表示装置の外部に設置された、例えばパーソナルコンピュータ（パソコン）などの外部映像源５０から出力された、映像信号ＤＡＶおよび映像を表示する際に必要な垂直同期信号や水平同期信号などの制御信号ＳＣ１が入力される。なお、電源断検知部１１を「緊急情報検知部」といい、ＲＯＭ１３を「記憶部」という場合がある。 First, the normal operation (normal drive mode) of the liquid crystal display device will be described. The signal processing unit 10 includes a power-off detection unit 11, a video processing unit 12, a timing control unit 14, and a read only memory (ROM) 13. The video processing unit 12 includes a video signal DAV output from an external video source 50 such as a personal computer (personal computer) installed outside the liquid crystal display device and a vertical synchronization signal necessary for displaying video. A control signal SC1 such as a horizontal synchronization signal is input. The power-off detection unit 11 may be referred to as an “emergency information detection unit”, and the ROM 13 may be referred to as a “storage unit”.
　映像処理部１２は、外部から与えられた映像信号ＤＡＶに基づいて生成した映像データＤＶと制御信号ＳＣ１を、タイミング制御部１４に出力する。タイミング制御部１４は、制御信号ＳＣ１に基づいてデータ信号線駆動回路用制御信号Ｓｓｃ、走査信号線駆動回路用制御信号Ｓｇｃを生成し、所定のタイミングで、映像データＤＶとデータ信号線駆動回路用制御信号Ｓｓｃを後述するデータ信号線駆動回路２２に出力し、走査信号線駆動回路用制御信号Ｓｇｃを走査信号線駆動回路２３に出力する。 The video processing unit 12 outputs the video data DV generated based on the video signal DAV given from the outside and the control signal SC1 to the timing control unit 14. The timing controller 14 generates a data signal line drive circuit control signal Ssc and a scanning signal line drive circuit control signal Sgc based on the control signal SC1, and at a predetermined timing, the video data DV and the data signal line drive circuit The control signal Ssc is output to the data signal line driving circuit 22 described later, and the scanning signal line driving circuit control signal Sgc is output to the scanning signal line driving circuit 23.
　ディスプレイ部２０は、映像を表示する液晶パネル２１と、液晶パネル２１を駆動するデータ信号線駆動回路２２および走査信号線駆動回路２３と、液晶パネル２１の背面側からバックライト光を照射するバックライトユニット２４とを含む。バックライトユニット２４の端部には、赤色（Ｒ）、緑色（Ｇ）、青色（Ｂ）の各ＬＥＤ（Light Emitting Diode）やＣＣＦＬ（Cathode Fluorescent Lamp）などの発光素子が取り付けられている。なお、液晶パネル２１を「表示パネル」という場合がある。 The display unit 20 includes a liquid crystal panel 21 that displays an image, a data signal line drive circuit 22 and a scanning signal line drive circuit 23 that drive the liquid crystal panel 21, and a backlight that emits backlight light from the back side of the liquid crystal panel 21. Unit 24. At the end of the backlight unit 24, light emitting elements such as red (R), green (G), and blue (B) LEDs (Light Emitting Diode) and CCFL (Cathode Fluorescent Lamp) are attached. The liquid crystal panel 21 may be referred to as a “display panel”.
　液晶パネル２１には、ｍ本のデータ信号線ＳＬと、ｎ本の走査信号線ＧＬと、これらのデータ信号線ＳＬと走査信号線ＧＬとの各交差点に対応して配置された（ｍ×ｎ）個の画素回路２７とが形成されている。各画素回路２７は、対応する交差点を通過する走査信号線ＧＬにゲート電極が接続されると共に、当該交差点を通過する各データ信号線ＳＬにソース電極が接続された薄膜トランジスタ２８（Thin Film Transistor：ＴＦＴ）、および、ＴＦＴ２８のドレイン電極に接続された画素電極と、複数個の画素回路２７に共通的に設けられた共通電極と、画素電極と共通電極との間に挟持された液晶層を含む。画素電極と共通電極は、それらの間に挟持された液晶層と共に液晶容量２９を構成する。液晶容量２９は映像データＤＶに基づいて生成されたアナログ信号であるデータ電圧を保持する。液晶パネル２１に封入される液晶はノーマリホワイト型であっても、ノーマリブラック型であっても良い。なお、図１には、説明の便宜上、１画素分の画素回路２７と、当該画素回路２７に接続されたデータ信号線ＳＬおよび走査信号線ＧＬのみが記載されている。 In the liquid crystal panel 21, m data signal lines SL, n scanning signal lines GL, and the intersections of the data signal lines SL and the scanning signal lines GL are arranged (m × n). ) Pixel circuits 27 are formed. Each pixel circuit 27 has a thin film transistor 28 (Thin Film Transistor: TFT) having a gate electrode connected to the scanning signal line GL passing through the corresponding intersection and a source electrode connected to each data signal line SL passing through the intersection. ), A pixel electrode connected to the drain electrode of the TFT 28, a common electrode provided in common to the plurality of pixel circuits 27, and a liquid crystal layer sandwiched between the pixel electrode and the common electrode. The pixel electrode and the common electrode constitute a liquid crystal capacitor 29 together with the liquid crystal layer sandwiched between them. The liquid crystal capacitor 29 holds a data voltage that is an analog signal generated based on the video data DV. The liquid crystal sealed in the liquid crystal panel 21 may be a normally white type or a normally black type. For convenience of explanation, FIG. 1 shows only a pixel circuit 27 for one pixel, and a data signal line SL and a scanning signal line GL connected to the pixel circuit 27.
　データ信号線駆動回路２２は、データ信号線駆動回路用制御信号Ｓｓｃに応じて、映像データＤＶに基づき、その内部の図示しないシフトレジスタおよびサンプリングラッチ回路などを動作させ、図示しないＤＡ変換回路で映像データＤＶをアナログ信号に変換することによりデータ電圧を生成し、データ信号線ＳＬに印加する。データ信号線駆動回路用制御信号Ｓｓｃには、例えばソーススタートパルス信号、ソースクロック信号、ラッチストローブ信号などが含まれる。なお、図１では、複数個のデータ信号線駆動回路２２が基板２２ａに実装されており、タイミング制御部１４から与えられる映像データＤＶおよびデータ信号線駆動回路用制御信号Ｓｓｃは基板２２ａを介して各データ信号線駆動回路２２に与えられる。 The data signal line drive circuit 22 operates a shift register and a sampling latch circuit (not shown) inside the data signal DV based on the video data DV in accordance with the control signal Ssc for the data signal line drive circuit. A data voltage is generated by converting the data DV into an analog signal and applied to the data signal line SL. The data signal line driver circuit control signal Ssc includes, for example, a source start pulse signal, a source clock signal, a latch strobe signal, and the like. In FIG. 1, a plurality of data signal line driving circuits 22 are mounted on the substrate 22a, and the video data DV and the data signal line driving circuit control signal Ssc given from the timing control unit 14 are transmitted via the substrate 22a. The signal is supplied to each data signal line driving circuit 22.
　走査信号線駆動回路２３は、走査信号線駆動回路用制御信号Ｓｇｃに応じて、その内部の図示しないシフトレジスタなどを動作させることによりアクティブな走査信号を生成し、当該走査信号を各走査信号線ＧＬに順に印加する。走査信号線駆動回路用制御信号Ｓｇｃには、例えばゲートクロック信号およびゲートスタートパルス信号が含まれる。なお、図１では、複数個の走査信号線駆動回路２３が基板２３ａに実装されており、タイミング制御部１４から与えられる走査信号線駆動回路用制御信号Ｓｇｃは基板２３ａを介して各走査信号線駆動回路２３に与えられる。なお、データ信号線駆動回路２２および走査信号線駆動回路２３をまとめて「駆動回路部」という場合がある。 The scanning signal line driving circuit 23 generates an active scanning signal by operating an internal shift register (not shown) in accordance with the scanning signal line driving circuit control signal Sgc, and outputs the scanning signal to each scanning signal line. It applies to GL in order. The scanning signal line drive circuit control signal Sgc includes, for example, a gate clock signal and a gate start pulse signal. In FIG. 1, a plurality of scanning signal line driving circuits 23 are mounted on the substrate 23a, and the scanning signal line driving circuit control signal Sgc given from the timing control unit 14 is sent to each scanning signal line via the substrate 23a. It is given to the drive circuit 23. The data signal line drive circuit 22 and the scanning signal line drive circuit 23 may be collectively referred to as “drive circuit unit”.
　アクティブな走査信号を与えられた走査信号線ＧＬに接続された各画素回路２７の液晶容量２９に、データ信号線駆動回路２２によって生成されたデータ電圧が書き込まれる。これにより、データ電圧が書き込まれた画素回路２７の液晶層の透過率が制御され、画素回路２７を透過するバックライト光が変化する。このようにして、映像データＤＶに応じた映像が液晶パネル２１に表示される。 The data voltage generated by the data signal line driving circuit 22 is written into the liquid crystal capacitor 29 of each pixel circuit 27 connected to the scanning signal line GL to which the active scanning signal is applied. Thereby, the transmittance of the liquid crystal layer of the pixel circuit 27 to which the data voltage is written is controlled, and the backlight light transmitted through the pixel circuit 27 changes. In this way, an image corresponding to the image data DV is displayed on the liquid crystal panel 21.
　ＴＦＴ２８のチャネル層には、酸化物半導体、特にＩｎ－Ｇａ－Ｚｎ－Ｏ（酸化インジウムガリウム亜鉛）からなる半導体が使用される。なお、以下の説明では、ＴＦＴ２８のチャネル層はＩｎ－Ｇａ－Ｚｎ－Ｏによって構成されているとして説明するが、Ｉｎ－Ｇａ－Ｚｎ－Ｏに限定されず、他の酸化物半導体を含んでいても良い。なお、チャネル層に酸化物半導体を含むＴＦＴ２８の詳細については後述する。 For the channel layer of the TFT 28, an oxide semiconductor, particularly a semiconductor made of In—Ga—Zn—O (indium gallium zinc oxide) is used. In the following description, the channel layer of the TFT 28 is described as being composed of In—Ga—Zn—O. However, the channel layer is not limited to In—Ga—Zn—O and includes other oxide semiconductors. Also good. Note that details of the TFT 28 including an oxide semiconductor in the channel layer will be described later.
　また、本実施形態に係る液晶表示装置は、カラー映像を表示するための方式として、フィールドシーケンシャル方式を採用する。フィールドシーケンシャル方式は、導光板２５の端部に取り付けられた、赤色（Ｒ）、緑色（Ｇ）、青色（Ｂ）の各ＬＥＤ２６ｒ、２６ｇ、２５ｂを時分割によって順に切り換えると共に、それと同期して液晶パネル２１に各発光素子の光の色に対応する色のデータを順に与えてその透過状態を制御し、観察者の網膜上で加法混色を行う方式である。フィールドシーケンシャル方式によれば、１つの画素回路２７に複数の副画素回路を形成しなくてもカラー表示が可能になるので、高解像度化に好適である。この場合、各画素回路２７にカラーフィルタを形成する必要がないので、カラーフィルタによってよって吸収されることなく画素回路２７を透過する。このため、発光素子から出射される光の利用効率が向上する。なお、ＬＥＤの発光色は、赤色、緑色、青色の組合せに限定されず、例えばシアン、マゼンタ、イエローの組合せなどであってもよい。 In addition, the liquid crystal display device according to the present embodiment employs a field sequential method as a method for displaying a color image. In the field sequential method, the red (R), green (G), and blue (B) LEDs 26r, 26g, and 25b attached to the end of the light guide plate 25 are sequentially switched in a time-sharing manner, and the liquid crystal is synchronized therewith. In this method, color data corresponding to the light color of each light emitting element is sequentially given to the panel 21 to control its transmission state, and additive color mixing is performed on the retina of the observer. According to the field sequential method, color display is possible without forming a plurality of sub-pixel circuits in one pixel circuit 27, which is suitable for high resolution. In this case, since it is not necessary to form a color filter in each pixel circuit 27, it passes through the pixel circuit 27 without being absorbed by the color filter. For this reason, the utilization efficiency of the light radiate | emitted from a light emitting element improves. Note that the emission color of the LED is not limited to a combination of red, green, and blue, and may be, for example, a combination of cyan, magenta, and yellow.
　このような通常駆動モードにおいて、信号処理部１０およびディスプレイ部２０に含まれる各構成要素は、外部電源４０から供給される電力ＳＶ１によって動作している。 In such a normal drive mode, each component included in the signal processing unit 10 and the display unit 20 is operated by the electric power SV1 supplied from the external power supply 40.
　次に、外部電源４０から供給されていた電力ＳＶ１の供給が停止された場合について説明する。外部電源４０からの電力ＳＶ１の供給が停止された場合には、災害などによる予期しない緊急事態が発生したことによる異常な電源断の場合（緊急駆動モード）と、例えば操作者が液晶表示装置の終了ボタンを押下することによって動作を終了する正常な電源断の場合（正常終了モード）とがある。 Next, the case where the supply of the electric power SV1 supplied from the external power supply 40 is stopped will be described. When the supply of the electric power SV1 from the external power source 40 is stopped, when an unexpected power failure occurs due to an unexpected emergency due to a disaster or the like (emergency drive mode), for example, the operator can use the liquid crystal display device. There is a case of normal power-off (normal end mode) in which the operation is ended by pressing the end button.
　信号処理部１０に設けられた電源断検知部１１は、外部電源４０からの電力ＳＶ１が供給されているか否かを常に監視し、外部電源４０からの電力ＳＶ１の供給が停止されたことを検知すると、その電源断が異常な電源断または正常な電源断のいずれであるかを判定する。具体的には、電源断検知部１１は、終了ボタンが押下された場合など、信号処理部１０内に設けられた基板が信号を検知したときに開始される終了シーケンスを経ている場合には正常な電源断と判定し、そうでない場合には異常な電源断と判定する。判定の結果、電源断検知部１１は、それが異常な電源断であると判定した場合には、電力ＳＶ１の供給が異常な電源断によって停止されたことを示す緊急停止信号Ｓｅｓを映像処理部１２とバッテリ回路部３０に出力する。バッテリ回路部３０は、電源断検知部１１から緊急停止信号Ｓｅｓを与えられると、信号処理部１０とディスプレイ部２０に電力ＳＶ２の供給を開始する。これにより、信号処理部１０およびディスプレイ部２０は動作可能になる。 The power interruption detection unit 11 provided in the signal processing unit 10 always monitors whether or not the electric power SV1 from the external power source 40 is supplied, and detects that the supply of the electric power SV1 from the external power source 40 has been stopped. Then, it is determined whether the power-off is an abnormal power-off or a normal power-off. Specifically, the power-off detection unit 11 is normal when a termination sequence started when a substrate provided in the signal processing unit 10 detects a signal, such as when an end button is pressed. If it is not, it is determined that the power supply is abnormal. As a result of the determination, when it is determined that the power-off detection unit 11 is an abnormal power-off, the video processing unit outputs an emergency stop signal Ses indicating that the supply of the power SV1 is stopped due to the abnormal power-off. 12 and the battery circuit unit 30. The battery circuit unit 30 starts supplying the electric power SV2 to the signal processing unit 10 and the display unit 20 when an emergency stop signal Ses is given from the power-off detection unit 11. Thereby, the signal processing unit 10 and the display unit 20 become operable.
　映像処理部１２は、緊急停止信号Ｓｅｓを与えられると、外部映像源５０から与えられる映像信号ＤＡＶおよびその制御信号ＳＣ１の処理を停止すると共に、ＲＯＭ１３にあらかじめ格納されている緊急情報データＥＭＤを読み出し、緊急情報データＥＭＤと緊急情報データＥＭＤに基づいて生成した制御信号Ｓｍｓｃとをタイミング制御部１４に出力する。タイミング制御部１４は、緊急情報を表示するために必要な制御信号Ｓｍｓｃ、Ｓｍｇｃを生成し、緊急情報データＥＭＤと制御信号Ｓｍｓｃをデータ信号線駆動回路２２に出力し、制御信号Ｓｍｇｃを走査信号線駆動回路２３に出力する。 When receiving the emergency stop signal Ses, the video processing unit 12 stops the processing of the video signal DAV supplied from the external video source 50 and its control signal SC1, and reads the emergency information data EMD stored in advance in the ROM 13. The emergency information data EMD and the control signal Smsc generated based on the emergency information data EMD are output to the timing control unit 14. The timing control unit 14 generates the control signals Smsc and Smgc necessary for displaying the emergency information, outputs the emergency information data EMD and the control signal Smsc to the data signal line driving circuit 22, and outputs the control signal Smgc to the scanning signal line. Output to the drive circuit 23.
　また、ディスプレイ部２０の液晶パネル２１には、バッテリ回路部３０から供給された電力ＳＶ２を使用して、信号処理部１０から与えられた緊急表示データに基づき生成されたデータ電圧が各画素回路２７に書き込まれる。すべての画素回路２７にデータ電圧の書込が終了すると、バッテリ回路部３０は、信号処理部１０およびディスプレイ部２０への電力ＳＶ２の供給を停止する。しかし、画素回路２７のＴＦＴ２８のチャネル層は酸化物半導体を含むので、ＴＦＴ２８がオフ状態になってもリーク電流は非常に少ない。このため、書き込まれたデータ電圧は長時間に渡って画素回路２７に保持され続ける。 In addition, the liquid crystal panel 21 of the display unit 20 uses the power SV2 supplied from the battery circuit unit 30 and the data voltage generated based on the emergency display data provided from the signal processing unit 10 is applied to each pixel circuit 27. Is written to. When the writing of the data voltage to all the pixel circuits 27 is completed, the battery circuit unit 30 stops supplying the power SV2 to the signal processing unit 10 and the display unit 20. However, since the channel layer of the TFT 28 of the pixel circuit 27 includes an oxide semiconductor, the leakage current is very small even when the TFT 28 is turned off. For this reason, the written data voltage is continuously held in the pixel circuit 27 for a long time.
　このとき、バックライトユニット２４には、電力ＳＶ２は供給されない。このため、緊急駆動時には、赤色、緑色、青色の各ＬＥＤ２６ｒ、２６ｇ、２６ｂはいずれも光を出射しない。しかし、導光板２５の背面側から液晶パネル２１に入射した外光がバックライト光として機能する。液晶パネル２１の各画素回路２７にはカラーフィルタが形成されていないので、緊急情報は白黒映像として表示される。さらに、液晶がノーマリホワイトタイプであれば、液晶パネル２１に緊急情報を表示する際に、緊急情報が表示されていない画素回路２７、すなわちデータ電圧が書き込まれていない画素回路２７では外光が透過するので、緊急情報と共に液晶表示装置の背面側の風景が透けて見える。これにより、災害時には周囲の状況を判断しやすくなり、迅速な避難が可能になる。 At this time, the power SV2 is not supplied to the backlight unit 24. For this reason, during emergency driving, each of the red, green, and blue LEDs 26r, 26g, and 26b does not emit light. However, external light incident on the liquid crystal panel 21 from the back side of the light guide plate 25 functions as backlight light. Since each pixel circuit 27 of the liquid crystal panel 21 is not formed with a color filter, the emergency information is displayed as a monochrome image. Furthermore, if the liquid crystal is a normally white type, when displaying emergency information on the liquid crystal panel 21, external light is emitted from the pixel circuit 27 where no emergency information is displayed, that is, the pixel circuit 27 where no data voltage is written. Since it is transmitted, the scenery on the back side of the liquid crystal display device can be seen through with the emergency information. This makes it easier to determine the surrounding situation during a disaster and enables quick evacuation.
　一方、電源断検知部１１は発生した電源断が正常な電源断であると判定した場合には、電力ＳＶ１の供給が正常な理由によって停止されたことを示す電力供給信号Ｓｐｓを映像処理部１２とバッテリ回路部３０に出力する。バッテリ回路部３０は、電力供給信号Ｓｐｓを与えられると、信号処理部１０およびディスプレイ部２０に電力ＳＶ２の供給を開始する。これにより、信号処理部１０およびディスプレイ部２０は動作可能になる。 On the other hand, when the power-off detection unit 11 determines that the generated power-off is a normal power-off, the video processing unit 12 outputs a power supply signal Sps indicating that the supply of the power SV1 has been stopped for a normal reason. And output to the battery circuit unit 30. When the power supply signal Sps is given, the battery circuit unit 30 starts supplying the power SV2 to the signal processing unit 10 and the display unit 20. Thereby, the signal processing unit 10 and the display unit 20 become operable.
　映像処理部１２は、電力供給信号Ｓｐｓを与えられると、外部映像源５０から与えられる映像信号ＤＡＶおよびその制御信号ＳＣ１の処理を停止する。その後、信号処理部１０およびディスプレイ部２０は、それぞれ通常終了処理を行う。このようにして、信号処理部１０およびディスプレイ部２０における通常終了処理が完了すると、バッテリ回路部３０は信号処理部１０およびディスプレイ部２０への電力ＳＶ２の供給を停止する。 When receiving the power supply signal Sps, the video processing unit 12 stops the processing of the video signal DAV supplied from the external video source 50 and its control signal SC1. Thereafter, the signal processing unit 10 and the display unit 20 each perform normal termination processing. Thus, when the normal termination process in the signal processing unit 10 and the display unit 20 is completed, the battery circuit unit 30 stops supplying the electric power SV2 to the signal processing unit 10 and the display unit 20.
＜１．２　ＴＦＴの特性＞
　図２は、チャネル層がＩｎ－Ｇａ－Ｚｎ－ＯからなるＴＦＴ２８のトランジスタ特性を示す図である。図２に示すように、ＴＦＴ２８の電気的特性を、チャネル層が低温ポリシリコン（ＬＴＰＳ：Low Temperature Poly Silicon）からなるＬＴＰＳ－ＴＦＴ、およびアモルファスシリコン（amorphous Silicon）からなるアモルファスシリコンＴＦＴの電気的特性と比較して説明する。まず各ＴＦＴがオン状態（ゲート電極に正電圧を印加）の場合、ＴＦＴ２８のドレイン電流ＩｄｄはアモルファスシリコンＴＦＴの場合よりも大きくなっている。このことから、ＴＦＴ２８の移動度は、アモルファスシリコンＴＦＴの場合より大きいことがわかる。具体的には、ＴＦＴ２８の移動度は、アモルファスシリコンＴＦＴに比べて２０倍以上大きい。このため、ＴＦＴ２８は、アモルファスシリコンＴＦＴよりも高速でオン状態とオフ状態を切り換えることができる。 <1.2 TFT characteristics>
FIG. 2 is a diagram showing the transistor characteristics of the TFT 28 whose channel layer is made of In—Ga—Zn—O. As shown in FIG. 2, the electrical characteristics of the TFT 28 are the same as those of an LTPS-TFT whose channel layer is made of low temperature poly silicon (LTPS) and an amorphous silicon TFT made of amorphous silicon. And will be described. First, when each TFT is in an on state (a positive voltage is applied to the gate electrode), the drain current Idd of the TFT 28 is larger than that of the amorphous silicon TFT. From this, it can be seen that the mobility of the TFT 28 is larger than that of the amorphous silicon TFT. Specifically, the mobility of the TFT 28 is 20 times greater than that of the amorphous silicon TFT. Therefore, the TFT 28 can be switched between the on state and the off state at a higher speed than the amorphous silicon TFT.
　また、各ＴＦＴ２８がオフ状態（ゲート電極に負電圧を印加）のときのドレイン電流Ｉｄｄはリーク電流を表しており、この値は小さい方が好ましい。この場合、ＴＦＴ２８のリーク電流は、ＬＴＰＳ－ＴＦＴおよびアモルファスシリコンＴＦＴの場合よりも大幅に小さくなっている。このことから、ＴＦＴ２８を画素回路２７のスイッチング素子として用いた場合、画素回路２７に書き込まれたデータ電圧は、ＬＴＰＳ－ＴＦＴやアモルファスシリコンＴＦＴの場合に比べてより長時間保持されることがわかる。具体的には、ＴＦＴ２８のリーク電流は、アモルファスシリコンＴＦＴの１／１０００以下、ＬＴＰＳ－ＴＦＴの１／１００００以下と非常に小さい。 Further, the drain current Idd when each TFT 28 is in an off state (a negative voltage is applied to the gate electrode) represents a leak current, and this value is preferably smaller. In this case, the leakage current of the TFT 28 is significantly smaller than that of the LTPS-TFT and the amorphous silicon TFT. From this, it can be seen that when the TFT 28 is used as a switching element of the pixel circuit 27, the data voltage written in the pixel circuit 27 is held for a longer time than in the case of the LTPS-TFT or the amorphous silicon TFT. Specifically, the leakage current of the TFT 28 is as small as 1/1000 or less of the amorphous silicon TFT and 1/10000 or less of the LTPS-TFT.
　このように、緊急事態により外部電源４０から電力ＳＶ１の供給が停止された場合、バッテリ回路部３０から供給される電力ＳＶ２を利用して画素回路２７に書き込まれたデータ電圧は、バッテリ回路部３０からの電力ＳＶ２の供給が停止された後も画素回路２７に長時間保持され、緊急情報を液晶パネル２１に長時間表示することができる。 Thus, when the supply of the electric power SV1 from the external power supply 40 is stopped due to an emergency situation, the data voltage written in the pixel circuit 27 using the electric power SV2 supplied from the battery circuit unit 30 is the battery circuit unit 30. Even after the supply of the electric power SV2 from is stopped, it is held in the pixel circuit 27 for a long time, and emergency information can be displayed on the liquid crystal panel 21 for a long time.
＜１．３　バックライトユニットの制御＞
　バックライトユニット２４の制御について説明する。図３は、バックライトユニット２４から出射されるバックライト光を示す図である。図３に示すように、バックライト光は通常駆動モードと緊急駆動モードとで異なる。通常駆動モードでは、１フレームを構成する３つのサブフレームの各々において、それぞれ赤色ＬＥＤ２６ｒ、緑色ＬＥＤ２６ｇ、および青色ＬＥＤ２６ｂを時分割して順に点灯させることにより、赤色、緑色、青色の光を順に出射させる。これにより、赤色、緑色、青色の光が液晶パネル２１に順に照射され、液晶パネル２１は映像データＤＶに応じたカラー映像を表示する。 <1.3 Control of backlight unit>
Control of the backlight unit 24 will be described. FIG. 3 is a diagram showing backlight light emitted from the backlight unit 24. As shown in FIG. 3, the backlight light is different between the normal drive mode and the emergency drive mode. In the normal drive mode, the red LED 26r, the green LED 26g, and the blue LED 26b are lit in order in a time-sharing manner in each of the three sub-frames constituting one frame, thereby emitting red, green, and blue light in order. . As a result, red, green, and blue light are sequentially applied to the liquid crystal panel 21, and the liquid crystal panel 21 displays a color image corresponding to the video data DV.
　一方、緊急駆動モードでは、すべてのＬＥＤ２６ｒ、２６ｇ、２６ｂを消灯させ、導光板２５の背面側から液晶パネル２１に向けて外光を透過させる。これにより、外光がバックライト光として機能し、液晶パネル２１には白黒の映像が表示される。 On the other hand, in the emergency drive mode, all the LEDs 26r, 26g, and 26b are turned off, and external light is transmitted from the back side of the light guide plate 25 toward the liquid crystal panel 21. As a result, the outside light functions as backlight light, and a black and white image is displayed on the liquid crystal panel 21.
＜１．４　通常駆動モード時および緊急駆動モード＞
　図４は、通常駆動モードおよび緊急駆動モードのそれぞれにおいて、映像データＤＶおよび緊急情報データＥＭＤに基づいてそれぞれ生成されたデータ電圧を書き込むタイミングを示す図である。図４に示すように、通常駆動モードでは、フィールドシーケンシャル駆動を行うので、表示すべき映像データＤＶに基づいて生成されたデータ電圧のうち、サブフレーム毎に発光させるべきバックライト光の色に対応するデータ電圧を各画素回路２７に書き込む。すなわち、赤色のデータ電圧が書き込まれたときには赤色ＬＥＤ２６ｒを点灯させ、緑色のデータ電圧が書き込まれたときには緑色ＬＥＤ２６ｇを点灯させ、青色のデータ電圧が書き込まれたときには青色ＬＥＤ２６ｂを点灯させることにより、カラー映像を表示する。 <1.4 Normal drive mode and emergency drive mode>
FIG. 4 is a diagram illustrating timings of writing data voltages generated based on the video data DV and the emergency information data EMD in each of the normal drive mode and the emergency drive mode. As shown in FIG. 4, in the normal drive mode, field sequential drive is performed, so that the data voltage generated based on the video data DV to be displayed corresponds to the color of the backlight light to be emitted for each subframe. The data voltage to be written is written in each pixel circuit 27. That is, the red LED 26r is turned on when the red data voltage is written, the green LED 26g is turned on when the green data voltage is written, and the blue LED 26b is turned on when the blue data voltage is written. Display video.
　一方、緊急駆動モードでは、ＲＯＭ１３から読み出した緊急情報データＥＭＤに基づき生成されたデータ電圧を最初の１フレーム期間に各画素回路２７に書き込む。このとき、各ＬＥＤ２６ｒ、２６ｇ、２６ｂはいずれも消灯されており、背面側から入射した外光が液晶パネル２１に照射される。このため、液晶パネル２１には、緊急情報が白黒の映像として表示される。 On the other hand, in the emergency drive mode, the data voltage generated based on the emergency information data EMD read from the ROM 13 is written to each pixel circuit 27 in the first one frame period. At this time, all the LEDs 26r, 26g, and 26b are turned off, and the liquid crystal panel 21 is irradiated with external light incident from the back side. Therefore, the emergency information is displayed on the liquid crystal panel 21 as a black and white video.
＜１．５　液晶表示装置の動作＞
　図５は、液晶表示装置が通常駆動モードによって映像を表示しているときに、電力ＳＶ１の供給が停止されたことによる割込処理を実行するための割込ルーチンを示すフロー図である。液晶表示装置が通常駆動モードで外部映像源５０から与えられる映像信号ＤＡＶに基づきカラー映像を表示しているときに、外部電源４０から供給されていた電力ＳＶ１の供給が停止される電源断が発生すると、その電源断の原因に応じて、液晶表示装置は通常駆動モードから緊急駆動モードまたは正常駆動モードに移行し、緊急情報を白黒映像で表示したり終了処理を行ったりする。そこで、図５を参照して、緊急駆動モードおよび正常終了モードによる割込動作を割込ルーチンとして説明する。 <1.5 Operation of liquid crystal display device>
FIG. 5 is a flowchart showing an interrupt routine for executing an interrupt process when the supply of power SV1 is stopped when the liquid crystal display device displays an image in the normal drive mode. When the liquid crystal display device displays a color image based on the video signal DAV supplied from the external video source 50 in the normal drive mode, a power interruption occurs in which the supply of the electric power SV1 supplied from the external power supply 40 is stopped. Then, the liquid crystal display device shifts from the normal drive mode to the emergency drive mode or the normal drive mode in accordance with the cause of the power cut-off, and displays the emergency information as a black and white image or performs a termination process. Therefore, referring to FIG. 5, the interrupt operation in the emergency drive mode and the normal end mode will be described as an interrupt routine.
　図５に示すように、ステップＳ１０では、電源断検知部１１は、外部電源４０からの電力ＳＶ１の供給が停止される電源断が発生したことを検知すると、それまで行っていた通常駆動を停止する。 As shown in FIG. 5, in step S <b> 10, when the power interruption detection unit 11 detects that a power interruption that stops the supply of the electric power SV <b> 1 from the external power supply 40 has occurred, it stops normal driving that has been performed so far. To do.
　ステップＳ１２では、電源断検知部１１は、発生した電源断が正常な電源断であるのか、異常な電源断であるのかを判定する。その結果、電源断が正常な電源断であると判定した場合にはステップＳ１４に進み、正常終了モードに移行する。一方、電源断が異常な電源断であると判定した場合には後述するステップＳ２２に進み、緊急駆動モードに移行する。 In step S12, the power-off detector 11 determines whether the generated power-off is a normal power-off or an abnormal power-off. As a result, when it is determined that the power is turned off normally, the process proceeds to step S14 and shifts to the normal end mode. On the other hand, if it is determined that the power cut is an abnormal power cut, the process proceeds to step S22, which will be described later, and shifts to the emergency drive mode.
　ステップＳ１２において電源断検知部１１は電源断が正常な電源断であると判定した場合には、ステップＳ１４において、信号処理部１０およびディスプレイ部２０に電力ＳＶ２を供給するために、電源を外部電源４０からバッテリ回路部３０に切り換える。そこで、電源断検知部１１は、バッテリ回路部３０に電力供給信号Ｓｐｓを出力する。これにより、電源はバッテリ回路部３０に切り換えられ、信号処理部１０よびディスプレイ部２０の正常終了処理に必要な電力ＳＶ２が信号処理部１０およびディスプレイ部２０に供給される。 If the power cut-off detection unit 11 determines in step S12 that the power cut is a normal power cut, in step S14, in order to supply the power SV2 to the signal processing unit 10 and the display unit 20, the power is turned off to the external power supply. The battery circuit unit 30 is switched from 40. Therefore, the power-off detection unit 11 outputs the power supply signal Sps to the battery circuit unit 30. As a result, the power source is switched to the battery circuit unit 30, and the electric power SV <b> 2 necessary for normal termination processing of the signal processing unit 10 and the display unit 20 is supplied to the signal processing unit 10 and the display unit 20.
　ステップＳ１６では、映像処理部１２は映像信号ＤＡＶおよびその制御信号ＳＣ１の処理を停止する。ステップＳ１８では、バッテリ回路部３０から供給される電力ＳＶ２によって信号処理部１０およびディスプレイ部２０における正常終了処理を行う。これにより、液晶表示装置は動作を正常に終了する。ステップＳ２０では、バッテリ回路部３０から信号処理部１０およびディスプレイ部２０への電力ＳＶ２の供給を停止し、割込ルーチンを終了する。 In step S16, the video processing unit 12 stops processing the video signal DAV and its control signal SC1. In step S <b> 18, normal termination processing is performed in the signal processing unit 10 and the display unit 20 by the electric power SV <b> 2 supplied from the battery circuit unit 30. As a result, the liquid crystal display device ends normally. In step S20, the supply of power SV2 from the battery circuit unit 30 to the signal processing unit 10 and the display unit 20 is stopped, and the interrupt routine is terminated.
　一方、ステップＳ１２において電源断検知部１１は電源断が異常な電源断であると判定した場合には、ステップＳ２２において、信号処理部１０およびディスプレイ部２０に電力ＳＶ２を供給するために、電源を外部電源４０からバッテリ回路部３０に切り換える。そこで、電源断検知部１１は、バッテリ回路部３０に緊急停止信号Ｓｅｓを出力する。これにより、緊急駆動を行うために必要な電力ＳＶ２が信号処理部１０およびディスプレイ部２０に供給される。 On the other hand, when the power-off detection unit 11 determines in step S12 that the power-off is an abnormal power-off, in step S22, the power-off detection unit 11 supplies power SV2 to the signal processing unit 10 and the display unit 20. Switching from the external power supply 40 to the battery circuit unit 30 is performed. Therefore, the power interruption detection unit 11 outputs an emergency stop signal Ses to the battery circuit unit 30. As a result, electric power SV2 necessary for emergency driving is supplied to the signal processing unit 10 and the display unit 20.
　ステップＳ２４では、映像処理部１２は、緊急駆動時に表示すべき緊急情報データＥＭＤをＲＯＭ１３から読み出す。ステップＳ２６では、読み出した緊急情報データＥＭＤと緊急情報データＥＭＤに基づいて生成した制御信号ＳＣ２とをタイミング制御部１４に出力する。これにより、液晶パネル２１の各画素回路２７には、緊急時に表示すべき緊急情報を表すデータ電圧が所定のタイミングでディスプレイ部に出力され、さらに液晶パネル２１の各画素回路２７に書き込まれる。 In step S24, the video processing unit 12 reads out from the ROM 13 emergency information data EMD to be displayed during emergency driving. In step S <b> 26, the read emergency information data EMD and the control signal SC <b> 2 generated based on the emergency information data EMD are output to the timing control unit 14. As a result, a data voltage representing emergency information to be displayed in an emergency is output to the display unit at a predetermined timing to each pixel circuit 27 of the liquid crystal panel 21 and further written to each pixel circuit 27 of the liquid crystal panel 21.
　ステップＳ２８では、バッテリ回路部３０から信号処理部１０およびディスプレイ部２０への電力ＳＶ２の供給を停止する。電力ＳＶ２の供給を停止した後も、画素回路２７に書き込まれたデータ電圧の電圧値がリーク電流によって所定値以下に低下するまで、画素回路２７は導光板２５を透過して背面側から入射する外光を透過させる。これにより、液晶パネル２１は白黒の緊急情報を表示し続ける。 In step S28, the supply of power SV2 from the battery circuit unit 30 to the signal processing unit 10 and the display unit 20 is stopped. Even after the supply of the power SV2 is stopped, the pixel circuit 27 passes through the light guide plate 25 and enters from the back side until the voltage value of the data voltage written in the pixel circuit 27 is lowered to a predetermined value or less by the leak current. Transmit external light. As a result, the liquid crystal panel 21 continues to display black and white emergency information.
＜１．６　効果＞
　本実施形態によれば、外部電源４０からの電力ＳＶ１の供給が異常な原因によって停止されたときには、電源をバッテリ回路部３０に切り換え、ＲＯＭ１３から読み出した緊急情報データＥＭＤを画素回路２７に書き込む。その後バッテリ回路部３０からの電力ＳＶ２の供給を停止しても、画素回路２７のＴＦＴ２８のチャネル層はＩｎ－Ｇａ－Ｚｎ－Ｏからなるので、リーク電流が小さいため、画素回路２７は書き込まれた緊急情報データＥＭＤを長時間に渡り保持することができる。 <1.6 Effect>
According to this embodiment, when the supply of the electric power SV1 from the external power supply 40 is stopped due to an abnormal cause, the power supply is switched to the battery circuit unit 30 and the emergency information data EMD read from the ROM 13 is written into the pixel circuit 27. After that, even if the supply of the electric power SV2 from the battery circuit unit 30 is stopped, the channel layer of the TFT 28 of the pixel circuit 27 is made of In—Ga—Zn—O. The emergency information data EMD can be held for a long time.
　また、バックライトユニット２４が点灯していなくても、画素回路２７は導光板２５を透過して背面側から入射する外光を透過させる。これにより、液晶パネル２１は白黒の緊急情報を表示し続けることができ、周囲の人に緊急情報を提供することができる。 In addition, even if the backlight unit 24 is not lit, the pixel circuit 27 transmits the external light incident from the back side through the light guide plate 25. As a result, the liquid crystal panel 21 can continue to display black and white emergency information, and can provide emergency information to surrounding people.
　さらに、カラーフィルタが形成されている液晶パネルと異なり、本実施形態の液晶パネル２１では、カラーフィルタが形成されていないので、白表示部での外光の透過率が高くなり、白表示部と黒表示部の輝度差が大きくなる。このため、外光下でも視認性の高い映像の表示が可能になる。 Further, unlike the liquid crystal panel in which the color filter is formed, in the liquid crystal panel 21 of the present embodiment, since the color filter is not formed, the external light transmittance in the white display portion is increased, and the white display portion The brightness difference in the black display area increases. For this reason, it is possible to display an image with high visibility even under external light.
＜２．第２の実施形態＞
＜２．１　液晶表示装置の構成および動作概要＞
　図６は、本発明の第２の実施形態に係る液晶表示装置の構成を示すブロック図である。図６に示すように、液晶表示装置は、ディスプレイ部２０と、ディスプレイ部２０を駆動するための信号処理部１０とを備えているが、バッテリ回路部は備えていない。ディスプレイ部２０の構成は図１に示すブロック図の構成と基本的に同一であるが、信号処理部１０に含まれる一部の構成要素は異なる。そこで、同じ構成要素に同じ参照符号を付して説明を省略し、異なる構成要素を中心に説明する。 <2. Second Embodiment>
<2.1 Configuration and operation overview of liquid crystal display device>
FIG. 6 is a block diagram showing a configuration of a liquid crystal display device according to the second embodiment of the present invention. As shown in FIG. 6, the liquid crystal display device includes a display unit 20 and a signal processing unit 10 for driving the display unit 20, but does not include a battery circuit unit. The configuration of the display unit 20 is basically the same as the configuration of the block diagram shown in FIG. 1, but some components included in the signal processing unit 10 are different. Therefore, the same components are denoted by the same reference numerals, description thereof is omitted, and different components will be mainly described.
　本実施形態に係る液晶表示装置も、第１の実施形態にかかる液晶表示装置と同様に、通常駆動モードでは、外部映像源５０から与えられる映像信号ＤＡＶに応じたカラー映像を表示する。通常駆動モードにおける液晶表示装置の動作は、第１の実施形態において説明した動作と同じであるので、その説明を省略する。 As in the liquid crystal display device according to the first embodiment, the liquid crystal display device according to the present embodiment also displays a color image corresponding to the video signal DAV supplied from the external video source 50 in the normal drive mode. Since the operation of the liquid crystal display device in the normal drive mode is the same as the operation described in the first embodiment, the description thereof is omitted.
　次に、緊急駆動モードにおける液晶表示装置の動作について説明する。図６に示すように、本実施形態の信号処理部１０は、図１に示す信号処理部１０の電源断検知部１１の代わりに、緊急信号検知部１５を備えている。緊急信号検知部１５は、緊急事態が発生したことを知らせる緊急通知信号Ｓｅｎが外部から入力されると、映像処理部１２に緊急停止信号Ｓｅｓを出力する。映像処理部１２は、緊急停止信号Ｓｅｓを与えられると、外部映像源５０から与えられる映像信号ＤＡＶおよびその制御信号ＳＣ１の処理を中断し、ＲＯＭ１３にあらかじめ格納されている緊急情報データＥＭＤを読み出し、読み出した緊急情報データＥＭＤと、緊急情報データＥＭＤに基づいて生成した制御信号ＳＣ２とをタイミング制御部１４に出力する。なお、緊急信号検知部１５を「緊急情報検知部」という場合がある。 Next, the operation of the liquid crystal display device in the emergency drive mode will be described. As illustrated in FIG. 6, the signal processing unit 10 according to the present exemplary embodiment includes an emergency signal detection unit 15 instead of the power-off detection unit 11 of the signal processing unit 10 illustrated in FIG. 1. The emergency signal detection unit 15 outputs an emergency stop signal Ses to the video processing unit 12 when an emergency notification signal Sen notifying that an emergency has occurred is input from the outside. When receiving the emergency stop signal Ses, the video processing unit 12 interrupts the processing of the video signal DAV supplied from the external video source 50 and its control signal SC1, reads out emergency information data EMD stored in advance in the ROM 13, The read emergency information data EMD and the control signal SC2 generated based on the emergency information data EMD are output to the timing control unit 14. The emergency signal detection unit 15 may be referred to as an “emergency information detection unit”.
　緊急駆動モードでは、タイミング制御部１４は、休止駆動を行うことによって液晶パネル２１に緊急情報を表示するために、緊急情報データＥＭＤおよびその制御信号ＳＣ２をディスプレイ部２０に出力する。これにより、緊急情報データＥＭＤが液晶パネル２１の各画素回路２７に書き込まれる。このとき、バックライトユニット２４の各ＬＥＤ２６ｒ、２６ｇ、２６ｂは消灯されているので、導光板２５の背面側から液晶パネル２１に向けて外光が照射される。その結果、液晶パネル２１は、通常駆動の場合よりも長い周期でリフレッシュを行う休止駆動によって緊急情報を白黒映像として表示する。 In the emergency drive mode, the timing control unit 14 outputs emergency information data EMD and its control signal SC2 to the display unit 20 in order to display emergency information on the liquid crystal panel 21 by performing pause driving. As a result, the emergency information data EMD is written in each pixel circuit 27 of the liquid crystal panel 21. At this time, the LEDs 26r, 26g, and 26b of the backlight unit 24 are turned off, so that external light is irradiated from the back side of the light guide plate 25 toward the liquid crystal panel 21. As a result, the liquid crystal panel 21 displays the emergency information as a black and white image by pause driving that refreshes at a longer cycle than in normal driving.
　このようにして、本実施形態では、緊急事態が発生したときにも外部電源４０からの給電は停止されないので、第１の実施形態の場合と異なり、所定の周期でリフレッシュを繰り返すことができ、それによって緊急情報を白黒映像で長時間表示し続けることができる。なお、緊急情報データＥＭＤには、１枚の静止画だけを表示可能なデータと、複数枚の静止画を表示可能な複数のデータとが含まれている。 Thus, in this embodiment, since power supply from the external power supply 40 is not stopped even in the event of an emergency, unlike the case of the first embodiment, refresh can be repeated at a predetermined cycle, As a result, emergency information can be continuously displayed in black and white video for a long time. The emergency information data EMD includes data capable of displaying only one still image and a plurality of data capable of displaying a plurality of still images.
　本実施形態の液晶パネル２１の各画素回路２７に設けられたＴＦＴ２８の構成、および通常駆動モードにおいてフィールドシーケンシャル方式によりカラー映像を表示することは、第１の実施形態の場合と同じであるので、それらの説明を省略する。なお、本実施形態では、緊急駆動モードでも外部電源４０から信号処理部１０およびディスプレイ部２０に電力ＳＶ１が供給されているので、ＴＦＴ２８のチャネル層はＩｎ－Ｇａ－Ｚｎ－Ｏでなくても良いが、Ｉｎ－Ｇａ－Ｚｎ－Ｏであれば書き込まれた緊急情報データＥＭＤを長時間保持することができるので、休止期間をより長くすることができる。 Since the configuration of the TFT 28 provided in each pixel circuit 27 of the liquid crystal panel 21 of the present embodiment and the display of a color image by the field sequential method in the normal drive mode are the same as in the case of the first embodiment, Those descriptions are omitted. In this embodiment, since the electric power SV1 is supplied from the external power supply 40 to the signal processing unit 10 and the display unit 20 even in the emergency drive mode, the channel layer of the TFT 28 may not be In—Ga—Zn—O. However, in the case of In—Ga—Zn—O, the written emergency information data EMD can be held for a long time, so that the suspension period can be made longer.
＜２．２　通常駆動モードおよび緊急駆動モード＞
　図７は、通常駆動モードおよび緊急駆動モードのそれぞれにおいて、映像データＤＶおよび緊急情報データＥＭＤに基づいてそれぞれ生成されたデータ電圧を書き込むタイミングを示す図である。図７に示すように、通常駆動モードは、図４に示す場合と同じであるので、その説明を省略する。 <2.2 Normal drive mode and emergency drive mode>
FIG. 7 is a diagram illustrating timings of writing data voltages generated based on the video data DV and the emergency information data EMD in each of the normal drive mode and the emergency drive mode. As shown in FIG. 7, the normal drive mode is the same as that shown in FIG.
　一方、緊急駆動モードでは、ＲＯＭ１３から読み出した緊急情報データＥＭＤを最初のフレーム期間に各画素回路２７に書き込む。このとき、各ＬＥＤ２６ｒ、２６ｇ、２６ｂは消灯されているが、外光が液晶パネル２１に照射されているので、緊急情報は白黒の映像として表示される。その後、緊急情報を表示した状態で、所定期間だけリフレッシュを休止する。所定の休止期間が経過すると、緊急情報データＥＭＤに基づいて生成されたデータ電圧を画素回路２７に再び書き込むことにより、リフレッシュを行う。このようにして、リフレッシュを繰り返すことにより、長時間に渡って緊急情報を表示し続けることができる。緊急情報データＥＭＤが１枚の静止画だけを表示可能なデータである場合には、当該静止画を繰り返して表示し続ける。一方、緊急情報データＥＭＤが複数枚の静止画の表示が可能なデータである場合には、休止期間毎に異なる静止画を表示する。 On the other hand, in the emergency drive mode, the emergency information data EMD read from the ROM 13 is written in each pixel circuit 27 in the first frame period. At this time, the LEDs 26r, 26g, and 26b are turned off, but since the external light is applied to the liquid crystal panel 21, the emergency information is displayed as a monochrome image. Thereafter, the refresh is suspended for a predetermined period while the emergency information is displayed. When a predetermined pause period elapses, refresh is performed by writing the data voltage generated based on the emergency information data EMD to the pixel circuit 27 again. Thus, by repeating the refresh, the emergency information can be continuously displayed for a long time. When the emergency information data EMD is data that can display only one still image, the still image is repeatedly displayed. On the other hand, when the emergency information data EMD is data that can display a plurality of still images, different still images are displayed for each pause period.
＜２．３　液晶表示装置における動作＞
　図８は、液晶表示装置が通常駆動によって映像を表示しているときに、緊急通知信号Ｓｅｎが入力されたことによる割込処理をするための割込ルーチンを示すフロー図である。液晶表示装置が通常駆動によってカラー映像を表示しているときに、緊急通知信号Ｓｅｎが突然入力されると、液晶表示装置は通常駆動モードから緊急駆動モードに移行し、緊急情報を表示する。そこで、図８を参照して、緊急駆動モードにおける動作を割込ルーチンとして説明する。 <2.3 Operation in liquid crystal display device>
FIG. 8 is a flowchart showing an interrupt routine for performing an interrupt process when the emergency notification signal Sen is input when the liquid crystal display device displays an image by normal driving. When the emergency notification signal Sen is suddenly input while the liquid crystal display device displays a color image by normal driving, the liquid crystal display device shifts from the normal driving mode to the emergency driving mode and displays emergency information. The operation in the emergency drive mode will be described as an interrupt routine with reference to FIG.
　図８に示すように、ステップＳ４０において、緊急信号検知部１５は、緊急通知信号Ｓｅｎが入力されているか否かを常に監視し、緊急通知信号Ｓｅｎを検知すると、映像処理部１２に緊急停止信号Ｓｅｓを出力する。これにより、映像処理部１２は緊急事態が発生したことを知ることができる。 As shown in FIG. 8, in step S40, the emergency signal detection unit 15 always monitors whether or not the emergency notification signal Sen is input. When the emergency notification signal Sen is detected, the emergency stop signal is sent to the video processing unit 12. Ses is output. Thereby, the video processing unit 12 can know that an emergency has occurred.
　映像処理部１２は、緊急停止信号Ｓｅｓを与えられると、ステップＳ４２では、外部映像源５０から与えられる映像信号ＤＡＶおよびその制御信号ＳＣ１の処理を中止し、通常駆動モードから緊急駆動モードに移行する。ステップＳ４４では、ＲＯＭ１３から緊急情報データＥＭＤを読み出す。 When receiving the emergency stop signal Ses, the video processing unit 12 stops the processing of the video signal DAV supplied from the external video source 50 and the control signal SC1 in step S42, and shifts from the normal drive mode to the emergency drive mode. . In step S44, the emergency information data EMD is read from the ROM 13.
　ステップＳ４６では、映像処理部１２は、ＲＯＭ１３から読み出した緊急情報データＥＭＤに基づいてその制御信号ＳＣ２を生成し、緊急情報データＥＭＤと制御信号ＳＣ２とをディスプレイ部２０に出力する。これにより、液晶パネル２１の各画素回路２７には、緊急情報データＥＭＤから生成されたデータ電圧が書き込まれる。 In step S46, the video processing unit 12 generates the control signal SC2 based on the emergency information data EMD read from the ROM 13, and outputs the emergency information data EMD and the control signal SC2 to the display unit 20. Thereby, the data voltage generated from the emergency information data EMD is written in each pixel circuit 27 of the liquid crystal panel 21.
　ステップＳ４８では、休止駆動の休止期間が経過するまで待機し、休止期間が経過すればステップＳ４４に戻ることを繰り返す。これにより、導光板２５を透過して液晶パネル２１に照射される外光により、液晶パネル２１は、緊急情報を白黒の映像として長時間に渡って表示し続ける。この場合、ＲＯＭ１３から読み出した緊急情報データＥＭＤが１枚の静止画だけを表示可能なデータである場合には、当該静止画を繰り返して表示し続ける。一方、緊急情報データＥＭＤが複数枚の静止画を表示可能な複数のデータである場合には、休止期間毎に異なる静止画を表示する。 In step S48, the process waits until the pause period of the pause drive elapses, and repeats returning to step S44 when the pause period elapses. Thereby, the liquid crystal panel 21 continues to display the emergency information as a black and white image for a long time by the external light that is transmitted through the light guide plate 25 and irradiated to the liquid crystal panel 21. In this case, when the emergency information data EMD read from the ROM 13 is data that can display only one still image, the still image is repeatedly displayed. On the other hand, when the emergency information data EMD is a plurality of data that can display a plurality of still images, a different still image is displayed for each pause period.
＜２．４　効果＞
　本実施形態によれば、外部から緊急通知信号Ｓｅｎが入力されれば、映像処理部１２はＲＯＭ１３から緊急情報データＥＭＤを読み出し、休止駆動によって休止期間毎に液晶パネル２１の画素回路２７に緊急情報データを書き込む。このとき、信号処理部１０およびディスプレイ部２０には外部電源４０から電力ＳＶ１が供給され続けているので、液晶パネル２１は、緊急情報を白黒の映像として表示し続けることができる。これにより、液晶パネル２１は白黒の緊急情報を表示し続けることができ、周囲の人に緊急情報を提供することができる。この緊急情報には、繰り返して表示される１枚の静止画によって表示される情報と、複数枚の静止画が順に表示される情報とがあり、液晶表示装置は緊急時の状況に応じて表示すべき情報を適宜選択して表示する。 <2.4 Effect>
According to the present embodiment, when the emergency notification signal Sen is input from the outside, the video processing unit 12 reads the emergency information data EMD from the ROM 13, and the emergency information is sent to the pixel circuit 27 of the liquid crystal panel 21 for each pause period by pause driving. Write data. At this time, since the electric power SV1 is continuously supplied from the external power source 40 to the signal processing unit 10 and the display unit 20, the liquid crystal panel 21 can continue to display the emergency information as a monochrome image. As a result, the liquid crystal panel 21 can continue to display black and white emergency information, and can provide emergency information to surrounding people. The emergency information includes information displayed by one still image that is repeatedly displayed, and information that sequentially displays a plurality of still images, and the liquid crystal display device displays information according to an emergency situation. Information to be selected is appropriately selected and displayed.
＜３．第３の実施形態＞
　液晶表示装置では、画素回路２７に同一極性の電圧を印加し続け、同じ映像を長時間表示させると、次の画面に切り替えても前の映像がうっすらと残ることがある。この現象は焼き付きとして広く知られている。そこで、このような焼き付きを防止するため、通常駆動では、サブフレーム毎に極性を反転させたデータ電圧が印加される。 <3. Third Embodiment>
In the liquid crystal display device, if the same polarity voltage is continuously applied to the pixel circuit 27 and the same image is displayed for a long time, the previous image may remain slightly even when the screen is switched to the next screen. This phenomenon is widely known as burn-in. Therefore, in order to prevent such burn-in, in normal driving, a data voltage whose polarity is inverted for each subframe is applied.
　そこで、本実施形態では、緊急駆動モードにおいて、この焼き付き現象を利用するために、第１の実施形態で説明した通常駆動が外部電源４０からの電力ＳＶ１の供給が異常断によって終了した後、緊急駆動モードに移行し、その直後の複数フレームにおいて、それぞれ同一極性のデータ電圧を印加し続ける。これにより、同一極性のデータ電圧が印加され続けた画素回路２７に映像の焼き付きが生じ、緊急情報を表す白黒映像が第１の実施形態の場合よりも長時間に渡って表示される。 Therefore, in this embodiment, in order to use this burn-in phenomenon in the emergency drive mode, the normal drive described in the first embodiment is stopped after the supply of the electric power SV1 from the external power supply 40 is terminated due to an abnormal interruption. The mode is shifted to the drive mode, and data voltages having the same polarity are continuously applied in a plurality of frames immediately after that. As a result, image sticking occurs in the pixel circuit 27 to which the data voltage of the same polarity has been continuously applied, and a black and white image representing emergency information is displayed for a longer time than in the first embodiment.
　本発明の第３の実施形態に係る液晶表示装置の構成は、図１に示す液晶表示装置の構成と同一であるので、その構成を示すブロック図およびその説明を省略する。また、画素回路２７に設けられたＴＦＴ２８の構成、および通常駆動モードではバックライトユニット２４をフィールドシーケンシャル方式で駆動することも第１の実施形態の場合と同一であるので、その説明を省略する。 Since the configuration of the liquid crystal display device according to the third embodiment of the present invention is the same as that of the liquid crystal display device shown in FIG. 1, a block diagram showing the configuration and description thereof are omitted. Further, since the configuration of the TFT 28 provided in the pixel circuit 27 and the driving of the backlight unit 24 by the field sequential method in the normal driving mode are the same as those in the first embodiment, the description thereof is omitted.
　図９は、本実施形態における通常駆動モードと緊急駆動モードにおいて、映像データＤＶおよび緊急情報データＥＭＤに基づいて画素回路２７にそれぞれ書き込むべきデータ電圧の書込みタイミングを示す図である。図９に示すように、通常駆動モードにおける動作は、第１の実施形態において説明した動作と同じであるのでその詳細な説明は省略するが、画素回路２７に印加するデータ電圧の極性をサブフレーム毎に反転させることによって焼き付きの発生を防止している。また、第１の実施形態の場合と同様に、通常駆動モードでは、フィールドシーケンシャル方式によってバックライトユニット２４を駆動し、カラー映像を表示する。 FIG. 9 is a diagram showing the write timing of data voltages to be written to the pixel circuit 27 based on the video data DV and the emergency information data EMD in the normal drive mode and the emergency drive mode in the present embodiment. As shown in FIG. 9, the operation in the normal drive mode is the same as the operation described in the first embodiment, and a detailed description thereof is omitted. However, the polarity of the data voltage applied to the pixel circuit 27 is set to a subframe. The occurrence of image sticking is prevented by reversing each time. Similarly to the case of the first embodiment, in the normal drive mode, the backlight unit 24 is driven by a field sequential method to display a color image.
　このような液晶表示装置において、災害が発生したことにより供給していた外部電源４０からの電力ＳＶ１の供給が停止すれば、電源断検知部１１は異常断が発生したことが検知する。この場合、第１の実施形態において説明したように、電源断検知部１１は電源を外部電源４０からバッテリ回路部３０に切り換えると共に、駆動モードを通常駆動モードから緊急表示モードに切り換える。 In such a liquid crystal display device, when the supply of the electric power SV1 from the external power supply 40 that has been supplied due to the occurrence of a disaster is stopped, the power-off detector 11 detects that an abnormal interruption has occurred. In this case, as described in the first embodiment, the power-off detection unit 11 switches the power source from the external power source 40 to the battery circuit unit 30 and switches the drive mode from the normal drive mode to the emergency display mode.
　これにより、映像処理部１２は、ＲＯＭ１３にあらかじめ格納されている緊急情報データＥＭＤを読み出してその制御信号ＳＣ２を生成し、緊急情報データＥＭＤと制御信号ＳＣ２をディスプレイ部２０に出力することにより、緊急表示モードに切り換えた直後の数フレーム期間に渡って、同一極性のデータ電圧を画素回路２７に繰り返し印加する。すなわち、図９に示すように、例えば各フレーム期間にすべて同一極性（図９ではすべて正極性）のデータ電圧を画素回路２７に印加する。その後、当該データ電圧を保持した状態でバッテリ回路部３０からの電力ＳＶ２の供給を停止する。 As a result, the video processing unit 12 reads the emergency information data EMD stored in advance in the ROM 13 to generate the control signal SC2, and outputs the emergency information data EMD and the control signal SC2 to the display unit 20, thereby A data voltage having the same polarity is repeatedly applied to the pixel circuit 27 over a period of several frames immediately after switching to the display mode. That is, as shown in FIG. 9, for example, data voltages having the same polarity (all positive in FIG. 9) are applied to the pixel circuit 27 in each frame period. Thereafter, the supply of the electric power SV2 from the battery circuit unit 30 is stopped while the data voltage is held.
＜３．１　効果＞
　本実施形態によれば、第１の実施形態の場合と同様に、画素回路２７に緊急情報を表す緊急情報データＥＭＤのデータ電圧が長時間に渡り保持されるだけでなく、さらにフレーム期間毎に同一の緊急情報データＥＭＤを画素回路２７に複数回書き込むことにより、画素回路２７に焼き付きが生じる。その結果、第１の実施形態の場合よりも長時間に渡って緊急情報が液晶パネル２１に表示され続ける。 <3.1 Effects>
According to the present embodiment, as in the case of the first embodiment, not only the data voltage of the emergency information data EMD representing the emergency information is held in the pixel circuit 27 for a long time, but also every frame period. By writing the same emergency information data EMD into the pixel circuit 27 a plurality of times, the pixel circuit 27 is burned. As a result, the emergency information continues to be displayed on the liquid crystal panel 21 for a longer time than in the case of the first embodiment.
＜４．チャネル層が酸化物半導体からなるＴＦＴ＞
　ＴＦＴ２８のチャネル層に含まれる酸化物半導体は、アモルファス酸化物半導体でも良く、結晶質部分を有する結晶質酸化物半導体でも良い。結晶質酸化物半導体としては、多結晶酸化物半導体、微結晶酸化物半導体、ｃ軸が層面に概ね垂直に配向した結晶質酸化物半導体などを使用することができる。 <4. TFT whose channel layer is made of an oxide semiconductor>
The oxide semiconductor contained in the channel layer of the TFT 28 may be an amorphous oxide semiconductor or a crystalline oxide semiconductor having a crystalline portion. As the crystalline oxide semiconductor, a polycrystalline oxide semiconductor, a microcrystalline oxide semiconductor, a crystalline oxide semiconductor in which the c-axis is oriented substantially perpendicular to the layer surface, or the like can be used.
　ＴＦＴ２８のチャネル層は、２層以上の積層膜であっても良い。この場合、チャネル層は、非晶質酸化物半導体と結晶質酸化物半導体とを含んでいても良く、結晶構造の異なる複数の結晶質酸化物半導体を含んでいても良く、複数の非晶質酸化物半導体を含んでいても良い。チャネル層が上層と下層とを含む２層構造を有する場合には、上層に含まれる酸化物半導体のエネルギーギャップは、下層に含まれる酸化物半導体のエネルギーギャップよりも大きいことが好ましい。ただし、２層のエネルギーギャップの差が比較的小さい場合には、下層の酸化物半導体のエネルギーギャップが上層の酸化物半導体のエネルギーギャップよりも大きくても良い。 The channel layer of the TFT 28 may be a laminated film of two or more layers. In this case, the channel layer may include an amorphous oxide semiconductor and a crystalline oxide semiconductor, may include a plurality of crystalline oxide semiconductors having different crystal structures, and a plurality of amorphous An oxide semiconductor may be included. In the case where the channel layer has a two-layer structure including an upper layer and a lower layer, the energy gap of the oxide semiconductor included in the upper layer is preferably larger than the energy gap of the oxide semiconductor included in the lower layer. However, in the case where the difference in energy gap between the two layers is relatively small, the energy gap of the lower oxide semiconductor may be larger than the energy gap of the upper oxide semiconductor.
　非晶質酸化物半導体および上記の各結晶質酸化物半導体の材料、構造、成膜方法、積層膜からなるチャネル層の構成などは、例えば特開２０１４－７３９９号公報に記載されている。参考のために、特開２０１４－７３９９号公報の開示内容のすべてを本明細書に援用する。 The material, structure, film forming method, and structure of a channel layer made of a laminated film of the amorphous oxide semiconductor and each crystalline oxide semiconductor described above are described in, for example, Japanese Patent Application Laid-Open No. 2014-7399. For reference, the entire disclosure of Japanese Patent Application Laid-Open No. 2014-7399 is incorporated herein by reference.
　酸化物半導体は、例えば、Ｉｎ、ＧａおよびＺｎのうち少なくとも１種の金属元素を含んでも良い。酸化物半導体には、例えば、Ｉｎ－Ｇａ－Ｚｎ－Ｏ系の半導体が含まれる。Ｉｎ－Ｇａ－Ｚｎ－Ｏ系の半導体は、Ｉｎ（インジウム）、Ｇａ（ガリウム）、Ｚｎ（亜鉛）の三元系酸化物である。Ｉｎ、ＧａおよびＺｎの割合（組成比）は特に限定されず、例えばＩｎ：Ｇａ：Ｚｎ＝２：２：１、Ｉｎ：Ｇａ：Ｚｎ＝１：１：１、Ｉｎ：Ｇａ：Ｚｎ＝１：１：２などでも良い。チャネル層は、Ｉｎ－Ｇａ－Ｚｎ－Ｏ系の半導体を含む酸化物半導体を用いて形成される。 The oxide semiconductor may contain, for example, at least one metal element of In, Ga, and Zn. Examples of the oxide semiconductor include an In—Ga—Zn—O-based semiconductor. The In—Ga—Zn—O-based semiconductor is a ternary oxide of In (indium), Ga (gallium), and Zn (zinc). The ratio (composition ratio) of In, Ga, and Zn is not particularly limited. For example, In: Ga: Zn = 2: 2: 1, In: Ga: Zn = 1: 1: 1, In: Ga: Zn = 1: It may be 1: 2. The channel layer is formed using an oxide semiconductor including an In—Ga—Zn—O-based semiconductor.
　Ｉｎ－Ｇａ－Ｚｎ－Ｏ系の半導体は、アモルファスでも良く、結晶質でも良い。結晶質Ｉｎ－Ｇａ－Ｚｎ－Ｏ系の半導体としては、ｃ軸が層面に概ね垂直に配向した結晶質Ｉｎ－Ｇａ－Ｚｎ－Ｏ系の半導体が好ましい。 The In—Ga—Zn—O-based semiconductor may be amorphous or crystalline. As the crystalline In—Ga—Zn—O-based semiconductor, a crystalline In—Ga—Zn—O-based semiconductor in which the c-axis is oriented substantially perpendicular to the layer surface is preferable.
　なお、結晶質Ｉｎ－Ｇａ－Ｚｎ－Ｏ系の半導体の結晶構造は、例えば、上述した特開２０１４－７３９９号公報、特開２０１２－１３４４７５号公報、特開２０１４－２０９７２７号公報などに開示されている。参考のために、特開２０１２－１３４４７５号公報および特開２０１４－２０９７２７号公報の開示内容のすべてを本明細書に援用する。Ｉｎ－Ｇａ－Ｚｎ－Ｏ系の半導体層を有するＴＦＴは、高い移動度（アモルファスシリコンＴＦＴに比べ２０倍超）および低いリーク電流（アモルファスシリコンＴＦＴに比べ１００分の１未満）を示す。このため、Ｉｎ－Ｇａ－Ｚｎ－Ｏ系の半導体層を有するＴＦＴは、複数の画素回路２７を含む液晶パネル２１の周辺に、液晶パネル２１と同じ基板上に設けられる走査信号線駆動回路２３やデータ信号線駆動回路２２に含まれるＴＦＴおよび画素回路２７に設けられるＴＦＴ２８として好適に用いられる。 Note that the crystal structure of a crystalline In—Ga—Zn—O-based semiconductor is disclosed in, for example, the above-described Japanese Patent Application Laid-Open Nos. 2014-7399, 2012-134475, and 2014-209727. ing. For reference, the entire contents disclosed in Japanese Patent Application Laid-Open Nos. 2012-134475 and 2014-209727 are incorporated herein by reference. A TFT having an In—Ga—Zn—O-based semiconductor layer exhibits high mobility (more than 20 times that of an amorphous silicon TFT) and low leakage current (less than 100 times that of an amorphous silicon TFT). For this reason, a TFT having an In—Ga—Zn—O-based semiconductor layer includes a scanning signal line driving circuit 23 provided on the same substrate as the liquid crystal panel 21 around the liquid crystal panel 21 including the plurality of pixel circuits 27. The TFT is preferably used as a TFT included in the data signal line driving circuit 22 and a TFT 28 provided in the pixel circuit 27.
　チャネル層は、Ｉｎ－Ｇａ－Ｚｎ－Ｏ系半導体に代えて、他の酸化物半導体を含んでいても良い。チャネル層は、例えばＩｎ－Ｓｎ－Ｚｎ－Ｏ系半導体（例えばＩｎ2 Ｏ3 －ＳｎＯ2 －ＺｎＯ；ＩｎＳｎＺｎＯ）を含んでも良い。Ｉｎ－Ｓｎ－Ｚｎ－Ｏ系半導体は、Ｉｎ（インジウム）、Ｓｎ（スズ）およびＺｎ（亜鉛）の三元系酸化物である。また、チャネル層は、Ｉｎ－Ａｌ－Ｚｎ－Ｏ系半導体、Ｉｎ－Ａｌ－Ｓｎ－Ｚｎ－Ｏ系半導体、Ｚｎ－Ｏ系半導体、Ｉｎ－Ｚｎ－Ｏ系半導体、Ｚｎ－Ｔｉ－Ｏ系半導体、Ｃｄ－Ｇｅ－Ｏ系半導体、Ｃｄ－Ｐｂ－Ｏ系半導体、ＣｄＯ（酸化カドミウム）、Ｍｇ－Ｚｎ－Ｏ系半導体、Ｉｎ－Ｇａ－Ｓｎ－Ｏ系半導体、Ｉｎ－Ｇａ－Ｏ系半導体、Ｚｒ－Ｉｎ－Ｚｎ－Ｏ系半導体、Ｈｆ－Ｉｎ－Ｚｎ－Ｏ系半導体などを含んでいても良い。ここで、Ａｌはアルミニウム、Ｔｉはチタン、Ｃｄはカドミウム、Ｇｅはゲルマニウム、Ｐｂは鉛、Ｍｇはマグネシウム、Ｚｒはジルコニウム、Ｈｆはハフニウムを表す。 The channel layer may contain another oxide semiconductor instead of the In—Ga—Zn—O-based semiconductor. The channel layer may include, for example, an In—Sn—Zn—O-based semiconductor (eg, In 2 O 3 —SnO 2 —ZnO; InSnZnO). The In—Sn—Zn—O-based semiconductor is a ternary oxide of In (indium), Sn (tin), and Zn (zinc). The channel layer includes an In—Al—Zn—O based semiconductor, an In—Al—Sn—Zn—O based semiconductor, a Zn—O based semiconductor, an In—Zn—O based semiconductor, a Zn—Ti—O based semiconductor, Cd—Ge—O based semiconductor, Cd—Pb—O based semiconductor, CdO (cadmium oxide), Mg—Zn—O based semiconductor, In—Ga—Sn—O based semiconductor, In—Ga—O based semiconductor, Zr— An In—Zn—O based semiconductor, an Hf—In—Zn—O based semiconductor, or the like may be included. Here, Al represents aluminum, Ti represents titanium, Cd represents cadmium, Ge represents germanium, Pb represents lead, Mg represents magnesium, Zr represents zirconium, and Hf represents hafnium.
　本願は、２０１６年３月８日に出願された「表示装置」という名称の日本の特願２０１６－４４１５９号に基づく優先権を主張する出願であり、この出願の内容は引用することによって本願の中に含まれる。 This application is an application claiming priority based on Japanese Patent Application No. 2016-44159 named “Display Device” filed on March 8, 2016, the contents of which are incorporated herein by reference. Included in.
　１０…信号処理部
　１１…電源断検知部（緊急情報検知部）
　１２…映像処理部
　１３…ＲＯＭ（記憶部）
　１４…タイミング制御部
　１５…緊急信号検知部（緊急情報検知部）
　２０…ディスプレイ部
　２１…液晶パネル
　２２…データ信号線駆動回路（駆動回路）
　２３…走査信号線駆動回路（駆動回路）
　２４…バックライトユニット
　２５…導光板
　２６…ＬＥＤ（発光素子）
　２７…画素回路
　２８…ＴＦＴ（薄膜トランジスタ）
　３０…バッテリ回路部
　４０…外部電源
　５０…外部映像源

　 10 ... Signal processing unit 11 ... Power failure detection unit (emergency information detection unit)
12 ... Video processing unit 13 ... ROM (storage unit)
14 ... Timing control unit 15 ... Emergency signal detection unit (emergency information detection unit)
DESCRIPTION OF SYMBOLS 20 ... Display part 21 ... Liquid crystal panel 22 ... Data signal line drive circuit (drive circuit)
23. Scanning signal line driving circuit (driving circuit)
24 ... Backlight unit 25 ... Light guide plate 26 ... LED (light emitting element)
27 ... Pixel circuit 28 ... TFT (Thin Film Transistor)
30 ... Battery circuit unit 40 ... External power supply 50 ... External video source

Claims (10)

  1. 　外部から入力された映像信号に基づき映像を表示するアクティブマトリクス型の表示装置であって、
    　前記映像を表示するディスプレイ部と、前記映像信号を処理して前記ディスプレイ部に出力する信号処理部とを備え、
    　前記ディスプレイ部は、
    　　複数の画素回路がマトリクス状に配置された表示パネルと、
    　　前記表示パネルを駆動する駆動回路部と、
    　　導光板と、前記導光板の端部に取り付けられた発光素子とを含み、前記発光素子から出射された光をバックライト光として前記表示パネルに照射するバックライトユニットとを備え、
    　前記信号処理部は、
    　　前記映像信号を与えられれば、前記表示パネルに前記映像を表示するための映像データを生成して出力する映像処理部と、
    　　前記映像データと、前記駆動回路部および前記バックライトユニットを制御する制御信号とを所定のタイミングで前記駆動回路部に出力するタイミング制御部と、
    　　緊急情報を前記表示パネルに表示するための緊急情報データを格納する記憶部と、
    　　緊急情報を検知したとき緊急停止信号を生成して、少なくとも前記映像処理部に出力する緊急情報検知部とを備え、
    　前記画素回路のスイッチング素子は、チャネル層に酸化物半導体を含む薄膜トランジスタであり、
    　前記映像処理部は、前記緊急情報検知部から前記緊急停止信号を与えられると、前記映像データの生成を停止し、前記記憶部に格納されている緊急情報データを読み出して前記駆動回路部に出力することにより、前記表示パネルに前記緊急情報を表示し、前記バックライトユニットは、前記発光素子を消灯させることを特徴とする、表示装置。     An active matrix display device that displays video based on an externally input video signal,
    A display unit that displays the video; and a signal processing unit that processes the video signal and outputs the processed video signal to the display unit.
    The display unit is
    A display panel in which a plurality of pixel circuits are arranged in a matrix;
    A drive circuit unit for driving the display panel;
    Including a light guide plate and a light emitting element attached to an end of the light guide plate, and comprising a backlight unit that irradiates the display panel with light emitted from the light emitting element as backlight light,
    The signal processing unit
    If the video signal is given, a video processing unit that generates and outputs video data for displaying the video on the display panel;
    A timing control unit for outputting the video data and a control signal for controlling the drive circuit unit and the backlight unit to the drive circuit unit at a predetermined timing;
    A storage unit for storing emergency information data for displaying emergency information on the display panel;
    An emergency information detection unit that generates an emergency stop signal when emergency information is detected and outputs the emergency stop signal to at least the video processing unit;
    The switching element of the pixel circuit is a thin film transistor including an oxide semiconductor in a channel layer,
    When the emergency stop signal is given from the emergency information detection unit, the video processing unit stops generating the video data, reads the emergency information data stored in the storage unit, and outputs the emergency information data to the drive circuit unit Thus, the emergency information is displayed on the display panel, and the backlight unit turns off the light emitting element.
  2. 　前記酸化物半導体は、インジウム（Ｉｎ）、ガリウム（Ｇａ），亜鉛（Ｚｎ）、酸素（Ｏ）を含むことを特徴とする、請求項１に記載の表示装置。 The display device according to claim 1, wherein the oxide semiconductor contains indium (In), gallium (Ga), zinc (Zn), and oxygen (O).
  3. 　外部電源からの電力の供給が停止されたときに、前記外部電源から切り換えることによって前記ディスプレイ部および前記信号処理部に電力の供給を可能にするバッテリ回路部をさらに備え、
    　前記緊急情報検知部は、前記外部電源からの電力の供給が停止したことを検知したとき、前記映像処理部と前記バッテリ回路部とに前記緊急停止信号を出力する電源断検知部であることを特徴とする、請求項１に記載の表示装置。     A battery circuit unit that enables power supply to the display unit and the signal processing unit by switching from the external power source when power supply from the external power source is stopped;
    The emergency information detection unit is a power-off detection unit that outputs the emergency stop signal to the video processing unit and the battery circuit unit when detecting that the supply of power from the external power source is stopped. The display device according to claim 1, wherein the display device is characterized.
  4. 　前記電源断検知部は、前記外部電源からの電力の供給停止原因が異常な原因によるものと判定した場合には、前記映像処理部と前記バッテリ回路部とに前記緊急停止信号を出力し、
    　前記バッテリ回路部は、前記緊急停止信号を与えられると、前記映像処理部と前記ディスプレイ部とに電力を供給し、
    　前記映像処理部は、前記緊急停止信号を与えられると、前記映像信号の処理を停止して、前記記憶部から読み出した前記緊急情報データを前記駆動回路部に出力し、
    　前記駆動回路は、前記緊急情報データに基づいて生成したデータ電圧を前記画素回路に書き込み、
    　前記バッテリ回路部は、前記データ電圧が前記画素回路に書き込まれた後に、前記映像処理部と前記ディスプレイ部への電力の供給を停止することを特徴とする、請求項３に記載の表示装置。     The power-off detection unit outputs the emergency stop signal to the video processing unit and the battery circuit unit when it is determined that the cause of the power supply stop from the external power source is due to an abnormal cause,
    The battery circuit unit, when given the emergency stop signal, supplies power to the video processing unit and the display unit,
    The video processing unit, when given the emergency stop signal, stops the processing of the video signal, and outputs the emergency information data read from the storage unit to the drive circuit unit,
    The drive circuit writes a data voltage generated based on the emergency information data to the pixel circuit,
    The display device according to claim 3, wherein the battery circuit unit stops supplying power to the video processing unit and the display unit after the data voltage is written to the pixel circuit.
  5. 　前記駆動回路部は、前記緊急情報データに基づいて同一極性のデータ電圧を生成し、前記画素回路に複数回書き込むことを特徴とする、請求項４に記載の表示装置。 The display device according to claim 4, wherein the drive circuit unit generates a data voltage having the same polarity based on the emergency information data and writes the data voltage to the pixel circuit a plurality of times.
  6. 　前記表示パネルは、ノーマリホワイトタイプの液晶表示装置であることを特徴とする、請求項４に記載の表示装置。 The display device according to claim 4, wherein the display panel is a normally white type liquid crystal display device.
  7. 　前記電源断検知部は、前記外部電源からの電力の供給停止原因が正常な原因によるものと判定した場合には、前記信号処理部と、前記ディスプレイ部と、前記バッテリ回路部とに電力供給信号を出力し、
    　前記バッテリ回路部は、前記電力供給信号を与えられると、前記信号処理部と前記ディスプレイ部に電力を供給し、前記信号処理部およびと前記ディスプレイ部は、電力を使用して正常終了処理を行うことを特徴とする、請求項３に記載の表示装置。     When it is determined that the cause of the power supply stop from the external power supply is due to a normal cause, the power-off detection unit supplies a power supply signal to the signal processing unit, the display unit, and the battery circuit unit. Output
    When the power supply signal is given, the battery circuit unit supplies power to the signal processing unit and the display unit, and the signal processing unit and the display unit perform normal termination processing using power. The display device according to claim 3, wherein:
  8. 　前記緊急情報検知部は、外部から緊急事態を示す緊急通知信号が入力されたことを検知したとき、前記映像処理部に緊急通知信号を出力する緊急信号検知部であり、
    　前記映像処理部は、前記緊急通知信号を与えられると、前記映像データの生成を停止して前記記憶部に格納されている緊急情報データを読み出し、前記駆動回路部は、前記タイミング制御部は、前記緊急情報データに基づくデータ電圧を休止期間の経過後毎に前記画素回路に書き込むことを特徴とする、請求項１に記載の表示装置。     The emergency information detection unit is an emergency signal detection unit that outputs an emergency notification signal to the video processing unit when detecting that an emergency notification signal indicating an emergency situation has been input from the outside,
    When the video processing unit is given the emergency notification signal, the video processing unit stops generating the video data and reads the emergency information data stored in the storage unit. 2. The display device according to claim 1, wherein a data voltage based on the emergency information data is written to the pixel circuit every time a pause period elapses.
  9. 　前記映像処理部は、前記緊急停止信号を与えられると、前記休止期間毎に前記記憶部から緊急情報データを読み出すことを特徴とする、請求項８に記載の表示装置。 9. The display device according to claim 8, wherein when the emergency stop signal is given, the video processing unit reads emergency information data from the storage unit for each pause period.
  10. 　前記バックライトユニットの前記発光素子は、異なる色を発光する複数種類の発光素子であり、前記映像を表示する通常駆動時には、前記バックライトユニットは前記複数種類の発光素子をサブフレーム毎に時分割して順に発光させることを特徴とする、請求項１に記載の表示装置。 The light emitting elements of the backlight unit are a plurality of types of light emitting elements that emit different colors. During normal driving for displaying the video, the backlight unit time-divides the plurality of types of light emitting elements for each subframe. The display device according to claim 1, wherein the display device sequentially emits light.
PCT/JP2017/008054 2016-03-08 2017-03-01 Display device WO2017154691A1 (en)

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