JP2014056095A - Liquid crystal display device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To adequately execute seizure preventing process of a liquid crystal display panel.SOLUTION: When a malfunction detection part (42) detects occurrence of a condition in which of a drive of a liquid crystal display panel should make an emergency stop, a power source switching part (56) switches a power supply path from a main power supply part (10) to a display driving part (31) to a cut off state, and the display driving part (31) executes electric charge emission processing of the liquid crystal display panel (61) using electric power supplied from a standby power source part (11).

Description

  The present invention relates to a liquid crystal display device that performs a predetermined OFF sequence (charge release processing) for preventing a burn-in phenomenon of a liquid crystal display panel when the power is turned off.

  Conventionally, it is known that when the same image is continuously displayed on the liquid crystal display panel for a long time, a so-called image sticking phenomenon occurs in which the image is fixed to the liquid crystal display panel like an afterimage.

  Also, if the power of the liquid crystal display device is turned off while displaying an image, the applied voltage immediately before the power is turned off remains applied to each pixel, and the same image continues to be drawn. Also in this case, it is known that a seizure phenomenon occurs.

  For this reason, in the conventional liquid crystal display device, when the power is turned off, a predetermined OFF sequence for discharging the charge applied to each pixel of the liquid crystal display panel is executed.

  For example, in Patent Document 1, in a liquid crystal display device provided in a gaming machine, when the power supply voltage of the gaming machine drops below a predetermined voltage value, liquid crystal molecules of all pixels in the liquid crystal display device are aligned in one direction. It is described that a burn-in phenomenon is prevented by performing a process (OFF sequence) for erasing the liquid crystal display.

  Further, in Patent Document 2, an electrolytic capacitor is provided in a power circuit, and when the power of the liquid crystal display device is turned off, black is applied to the entire screen of the liquid crystal display panel using the charge stored in the electrolytic capacitor. It is described that the image sticking phenomenon is prevented by drawing or performing a process (OFF sequence) for drawing a checkered pattern in which black and white is reversed every other pixel or several pixels.

JP 7-31728 A (published February 3, 1995) JP 2000-131671 (May 12, 2000)

  By the way, in a conventional liquid crystal display device, in general, a driving power source of a liquid crystal display panel and a power source of a host system that controls the operation of each part of the liquid crystal display device are shared.

  For this reason, in the conventional liquid crystal display device, when the power supply is normally turned off, in addition to the processing for releasing the charge applied to each pixel of the liquid crystal display panel (OFF sequence of the liquid crystal display panel), the host system Executes processing (OFF sequence for members other than the liquid crystal display panel) according to the respective members so as not to cause a malfunction in each member provided or each member other than the liquid crystal display panel whose power supply is controlled by the host system. After that, the power is turned off.

  However, when the OFF sequence cannot be normally executed due to power loss or the like, the state on the host system side is various, and the power consumed by each member other than the liquid crystal display panel being unable to execute the normal OFF sequence is It varies greatly depending on the status of the host system. For this reason, depending on the state on the host system side and the like, there is a case where sufficient power required for the OFF sequence of the liquid crystal display panel cannot be secured. Alternatively, if the power required for the OFF sequence of the liquid crystal display panel is to be secured, the OFF sequence (or the ON sequence) of members other than the liquid crystal display panel is affected, and the members may be defective.

  Further, in the configuration in which the OFF sequence is executed using the power stored in the electrolytic capacitor as in Patent Document 2, the power required for executing the OFF sequence varies depending on the state on the host system side, so the capacity of the electrolytic capacitor is optimized. There is also a problem that it cannot be converted.

  The present invention has been made in view of the above-mentioned problems, and the object thereof is to perform a process for preventing the image sticking phenomenon from occurring when the driving of the liquid crystal display panel is stopped in an emergency. This is to prevent the influence of the treatment from affecting other members.

  A liquid crystal display device according to an aspect of the present invention includes a liquid crystal display panel including a plurality of pixels, and a display driving unit that drives the liquid crystal display panel by controlling a voltage applied to each pixel according to image data. A display drive unit, and a main power supply unit that supplies power for driving the liquid crystal display panel to the display drive unit, and the display drive unit applies to each pixel when the drive of the liquid crystal display panel is stopped. A liquid crystal display device that performs a charge discharge process for discharging the accumulated charge, wherein a power supply for charging the display drive unit to execute the charge discharge process and a drive for the liquid crystal display panel are An abnormality detection unit that detects occurrence of an emergency stop condition that is a predetermined condition as a condition to be stopped, and a power supply path from the main power supply unit to the display drive unit is in a conduction state and a cutoff state. A power switching unit for switching, and when the abnormality detecting unit detects the occurrence of the emergency stop condition, the power switching unit switches the power supply path to a cut-off state, and the display driving unit is connected to the standby power source unit. The charge emission process is performed using the supplied power.

  According to the liquid crystal display device according to one embodiment of the present invention, when the driving of the liquid crystal display panel is stopped urgently, the image sticking phenomenon is prevented from occurring in the liquid crystal display panel, and the influence of the charge discharging process in the display driving unit is achieved. Can be prevented from reaching other members that operate using electric power supplied from the main power supply unit.

It is explanatory drawing which shows the structure of the electric power supply system in the liquid crystal display device concerning one Embodiment of this invention. It is explanatory drawing which shows the whole structure of the portable apparatus provided with the liquid crystal display device concerning one Embodiment of this invention. It is explanatory drawing which shows the structure of the main power supply part with which the liquid crystal display device concerning one Embodiment of this invention is equipped, a standby power supply part, and a power supply switching part. It is a flowchart which shows the flow of the control processing of the electric power supply in the liquid crystal display device concerning one Embodiment of this invention. It is explanatory drawing which shows the modification of a structure of the main power supply part with which the liquid crystal display device concerning one Embodiment of this invention is equipped, a standby power supply part, and a power supply switching part. It is explanatory drawing which shows the modification of a structure of the main power supply part with which the liquid crystal display device concerning one Embodiment of this invention is equipped, a standby power supply part, and a power supply switching part. It is explanatory drawing which shows the modification of a structure of the main power supply part with which the liquid crystal display device concerning one Embodiment of this invention is equipped, a standby power supply part, and a power supply switching part. It is explanatory drawing which shows the modification of a structure of the main power supply part with which the liquid crystal display device concerning one Embodiment of this invention is equipped, a standby power supply part, and a power supply switching part. It is explanatory drawing which shows the modification of a structure of the main power supply part with which the liquid crystal display device concerning one Embodiment of this invention is equipped, a standby power supply part, and a power supply switching part.

  An embodiment of the present invention will be described. In the present embodiment, the case where the present invention is applied to a liquid crystal display device provided in a portable device will be described. However, the application target of the present invention is not limited to this, and a liquid crystal display device alone or a liquid crystal display device is used. It can also be applied to other devices equipped.

(1-1. Overall configuration of portable device 1)
FIG. 2 is an explanatory diagram showing a configuration of the portable device (electronic device) 1 according to the present embodiment. As the mobile device 1, for example, a smart phone, a tablet terminal, a mobile phone, a PDA (Personal Digital Assistance), a notebook computer, a portable game machine, or the like can be used.

  As shown in FIG. 2, the mobile device 1 includes a control unit (host system) 2, an operation unit 3, a communication unit 4, an imaging unit 5, a voice input unit 6, a voice output unit 7, a storage unit 8, and a display device 9. The main power supply unit 10 and the standby power supply unit 11 are provided. The control unit 2 includes an operation control unit 21, a communication control unit 22, an imaging control unit 23, a voice input control unit 24, a voice output control unit 25, a storage control unit 26, a display control unit 27, and a power supply control unit 28. It has. The display device 9 includes a display driving unit 31 and a display unit 32.

  The operation unit 3 is for receiving an operation input from a user and transmitting it to the control unit 2. The configuration of the operation unit 3 is not particularly limited, and for example, various operation keys can be used. The operation unit 3 may be a touch panel that performs an operation input by touching the display screen of the display unit 32.

  The communication unit 4 communicates with other devices via a communication network. The communication network is not particularly limited. For example, the Internet, intranet, extranet, LAN, ISDN, VAN, CATV communication network, virtual private network, telephone line network, mobile communication network, satellite A communication network or the like is available. Also, the transmission medium constituting the communication network is not particularly limited. For example, the transmission medium such as IEEE1394, USB, power line carrier, cable TV line, telephone line, ADSL (Asymmetric Digital Subscriber Line) line or the like can be used. Infrared such as remote control, Bluetooth (registered trademark), IEEE 802.11 wireless, HDR (High Data Rate), NFC (Near Field Communication), DLNA (Digital Living Network Alliance), mobile phone network, satellite line, terrestrial digital It can also be used wirelessly such as on the network.

  The imaging unit 5 captures a surrounding image and generates image data.

  The voice input unit 6 collects surrounding voices and generates voice data.

  The sound output unit 7 outputs sound according to an instruction from the control unit 2.

  The storage unit 8 stores and reads various information according to instructions from the control unit 2. The configuration of the storage unit 8 is not particularly limited. For example, a semiconductor memory such as a mask ROM / EPROM / EEPROM (registered trademark) / flash ROM, or a programmable logic device (PLD) or a field programmable gate array (FPGA). Such logic circuits can be used.

  The display device 9 includes a display unit 32 having a large number of pixels and a display driving unit 31 that controls the operation of the display unit 32. The display unit 32 includes a liquid crystal display panel 61 and a backlight 62, and the display driving unit 31 applies to each pixel of the display unit 32 in accordance with image data transmitted from the control unit 2 (display control unit 27). By controlling the voltage to be driven, the liquid crystal display panel 61 is driven and the backlight 62 is turned on, so that an image corresponding to the image data is displayed on the display unit 32. Details of the display device 9 will be described later.

  The main power supply unit 10 supplies power for driving each unit of the portable device 1, and power supply to the display device 9 is also performed from the main power supply unit 10 at normal times. Details of the main power supply unit 10 will be described later.

  The standby power supply unit 11 performs a predetermined OFF sequence (charge release process) on the display device 9 when an emergency stop condition which is a predetermined condition as a condition for emergency stop of driving of the liquid crystal display panel 61 occurs. Supply power to perform. As the emergency stop condition, for example, when the output voltage of the main power supply unit 10 (or the output voltage of the battery provided in the main power supply unit 10) drops below a predetermined value, the software hang executed in the control unit 2 For example, when the battery power is removed, the battery provided in the main power supply unit 10 is removed. Details of the standby power supply unit 11 will be described later.

  The control unit 2 performs general control (processing) of the apparatus main body of the mobile device 1. The control unit 2 includes, for example, a computer device that includes an arithmetic processing unit such as a CPU or a dedicated processor, and a storage unit (not shown) such as a RAM, a ROM, or an HDD, and stores in the storage unit. By reading and executing various information and programs for performing various controls, the operation control unit 21, the communication control unit 22, the imaging control unit 23, the voice input control unit 24, the voice output control unit 25, and the storage The functions of the control unit 26, the display control unit 27, and the power supply control unit 28 are executed, and the operation of each unit of the mobile device 1 is controlled.

  The operation control unit 21 controls the operation of the operation unit 3 and receives information according to an instruction input from the user transmitted from the operation unit 3.

  The communication control unit 22 controls the operation of the communication unit 4 and performs communication with other devices.

  The imaging control unit 23 controls the operation of the imaging unit 5 and acquires image data captured by the imaging unit 5.

  The voice input control unit 24 controls the operation of the voice input unit 6 and acquires the voice data generated by the voice input unit 6.

  The audio output control unit 25 controls the operation of the audio output unit 7 to execute audio output.

  The storage control unit 26 controls the operation of the storage unit 8, stores various data in the storage unit 8, and reads out various data stored in the storage unit 8.

  The display control unit 27 displays image data to be displayed on the display unit 32 and various control information (for example, various control signals such as a clock signal, a vertical synchronization signal, a horizontal synchronization signal start pulse, a control command, and a packet). Output to the drive unit 31.

  The power supply control unit 28 controls power supply from the main power supply unit 10 or the standby power supply unit 11 to each unit of the portable device 1. Details of the power supply control unit 28 will be described later.

(1-2. Configuration of Power Supply System for Display Device 9 and Display Device 9)
Next, the configuration of the display device 9 and the power supply system for the display device 9 will be described. FIG. 1 is an explanatory diagram illustrating configurations of the power supply control unit 28, the display device 9, the main power supply unit 10, and the standby power supply unit 11.

  As shown in FIG. 1, the display drive unit 31 includes a frame memory 51, a timing generator 52, a source driver 53, a gate driver 54, a backlight drive unit 55, a power supply switching unit 56, and an OFF sequence storage unit 57. Yes. The display unit 32 includes a liquid crystal display panel 61 and a backlight 62.

  The liquid crystal display panel 61 includes a pair of substrates at least one of which is transparent, a liquid crystal layer sandwiched between the substrates, a plurality of scanning signal lines (gate lines), a plurality of data signal lines (source lines), A pixel provided at each intersection of the scanning signal line and the data signal line, each pixel including a pixel electrode and a counter electrode for applying a voltage to the liquid crystal layer, and the pixel electrode and the data signal A switching element that switches between a line and a conductive state is provided. The operation of the switching element of each pixel is controlled by a voltage applied to the scanning signal line connected to the switching element. In addition, a voltage corresponding to an image to be displayed on each pixel is supplied to the data signal line in synchronization with the operation timing of the switching element of each pixel connected to the data signal line.

  The configuration of the liquid crystal display panel is not particularly limited, and various conventionally known liquid crystal display panels can be used. In this embodiment, the channel layer is an oxide as the switching element provided in each pixel. An oxide semiconductor liquid crystal panel including a thin film transistor element made of a semiconductor is used. Note that an amorphous oxide material including In (indium), Ga (gallium), Zn (zinc), and O (oxygen) is particularly suitable as the oxide semiconductor, and is represented by zinc oxide (ZnO). A polycrystalline material (so-called IGZO) can also be used.

  Switching elements using oxide semiconductors (especially IGZO) have a very high OFF resistance compared to amorphous silicon and the like used in conventional liquid crystal display panels, so that the charges applied to each pixel can be stabilized over a long period of time. Can be held. For this reason, since it is possible to perform pause driving without performing the operation of writing the applied voltage to each pixel of the liquid crystal display panel during a period when the display image does not change, a conventional liquid crystal display device using a switching element made of amorphous silicon or the like Display can be driven at a lower frequency than that, thereby reducing power consumption.

  On the other hand, since the switching element using an oxide semiconductor has a very high OFF resistance as described above, when the power supply is interrupted without executing a normal OFF sequence due to a sudden power loss, etc. There is a characteristic that the charge applied to the pixels is difficult to escape, and the seizure phenomenon is likely to occur when the state where the charges remain in each pixel persists for a long time. Therefore, in the present embodiment, even when a sudden power loss or the like occurs, by executing the OFF sequence of the display device 9 using the power supplied from the standby power supply unit 11 to the display device 9, Electric charges applied to the pixels are released to prevent the occurrence of image sticking.

  The backlight 62 supplies light for display to the liquid crystal display panel 61. The configuration of the backlight 62 is not particularly limited, and various conventionally known configurations can be used. In this embodiment, the case of using a transmissive liquid crystal display panel that performs display using irradiation light from the backlight 62 is described, but the present invention is not limited to this. For example, a reflective liquid crystal display panel that performs display by reflecting light incident from the outside of the liquid crystal display panel may be used. In that case, the backlight 62 may be omitted.

  The frame memory 51 is an image memory that stores image data transferred from the display control unit 27 for at least one frame (one screen).

  The timing generator 52 generates a drive timing (drive pattern) for displaying the image data stored in the frame memory 51 on the display unit 32 based on the control signal input from the display control unit 27. The timing generator 52 supplies image data to the source driver 53 in synchronization with the drive timing, and various control signals (source clock for the source driver 53) for controlling the operations of the source driver 53 and the gate driver 54. And a source start pulse, and a gate clock and a gate start pulse for the gate driver 54).

  In addition, the timing generator 52 stores in the OFF sequence storage unit 57 when executing the OFF sequence of the liquid crystal display panel 61 for discharging the charge accumulated in each pixel of the liquid crystal display panel 61 to the outside of each pixel. Based on the stored data, a signal for causing each unit to execute an OFF sequence (charge release processing) is generated. Specifically, in the present embodiment, when executing the OFF sequence, the timing generator 52 displays an image (for example, a black image) corresponding to predetermined image data stored in the OFF sequence storage unit 57 on the display unit 32. Drive timing (drive pattern) for drawing is generated. The timing generator 52 provides the predetermined image data to the source driver 53 in synchronization with the drive timing, and generates various control signals for controlling the operations of the source driver 53 and the gate driver 54.

  Note that the image drawn on each pixel when the OFF sequence is executed is not limited to a black image. For example, a checkered pattern in which black and white is reversed every pixel or every several pixels may be drawn.

  The processing content of the OFF sequence (charge emission processing) is not particularly limited as long as it is a processing that can discharge the charge accumulated in each pixel of the liquid crystal display panel 61 to the outside of each pixel. For example, by connecting each data signal line to the ground or the same potential as the counter electrode with the switching element of each pixel conducting, or by short-circuiting a plurality of data signal lines to which charges of opposite polarity are applied You may make it discharge the electric charge of each pixel.

  The source driver 53 stores and outputs the image data input from the timing generator 52 for one line at the timing generated by the shift register. Specifically, the shift register of the source driver 53 sequentially shifts and outputs the source start pulse input from the timing generator 52 in synchronization with the source clock. Further, the source driver 53 selects a gradation voltage corresponding to the gradation represented by the image data output from the shift register, and outputs it as a data voltage to each data signal line in the liquid crystal display panel 61. Further, the source driver 53 has source amplifiers provided in the output stage in the same number as the source lines, and outputs data voltages to the source lines via the source amplifiers.

  The gate driver 54 generates a gate signal to be output to each scanning signal line in the liquid crystal display panel 61 based on the gate start pulse and gate clock input from the timing generator 52. Specifically, the gate driver 54 sequentially shifts the gate start pulse in synchronization with the gate clock by the shift register and outputs a gate signal. The gate driver 54 selects the scanning signal lines line-sequentially by outputting such a gate signal.

  The backlight drive unit 55 drives the backlight 62. As described above, a reflective liquid crystal display panel may be used, and in that case, the backlight 62 and the backlight driver 55 may be omitted.

  The power supply switching unit 56 determines the connection state between the main power supply unit 10 and the standby power supply unit 11 and each unit of the display device 9 according to the power supply switching signal input from the control unit 2. The first state in which each part is conducted and the second state in which the main power supply unit 10 and each part of the display device 9 are cut off and the standby power supply unit 11 and each part of the display device 9 are conducted are switched.

  The OFF sequence storage unit 57 stores data for determining the driving method of each pixel of the liquid crystal display panel 61 when the OFF sequence is executed. In the present embodiment, during execution of the OFF sequence, a voltage for drawing a black image is applied to each pixel of the liquid crystal display panel 61, so that the potential difference between electrodes (between the pixel electrode and the counter electrode) in each pixel is zero. Alternatively, a value close to that is set to prevent the occurrence of seizure phenomenon. However, as described above, the processing content of the OFF sequence (charge release processing) is not limited to this.

  The main power supply unit 10 includes a battery 71, a voltage conversion unit 72, a voltage detection unit 73, and an external power supply connection unit 74.

  The battery 71 is a power supply source that supplies power for operating each unit to each unit of the portable device 1. The configuration of the battery 71 is not particularly limited, and various conventionally known configurations can be used. In the present embodiment, the battery 71 is detachably attached to the mobile device 1, but is not limited thereto, and may be built in the mobile device 1.

  The voltage conversion unit 72 converts the output voltage from the battery 71 into a voltage corresponding to the drive voltage of each unit of the mobile device 1 according to the power distribution control signal input from the power distribution control unit 41, and outputs the voltage to each unit of the mobile device 1. Output.

  The voltage detection unit 73 detects the voltage of the battery 71 and transmits it to the control unit 2 and the external power supply connection unit 74.

  The external power source connection unit 74 connects the portable device 1 to an external power source (for example, a commercial power supply source, a power generation device, a power storage device, etc.), and charges the battery 71 using power supplied from the external power source. The external power supply connection unit 74 is configured to stop charging the battery 71 when the voltage detected by the voltage detection unit 73 reaches the predetermined charging voltage.

  The standby power supply unit 11 includes a charging unit 81, a voltage conversion unit 82, and a charging voltage detection unit 83.

  The charging unit 81 charges the power supplied from the main power supply unit 10. The configuration of the charging unit 81 is not particularly limited as long as it is a configuration capable of charging power for causing the display device 9 to execute the OFF sequence. For example, a capacitor, a secondary battery (storage battery), or the like is used. be able to.

  The voltage conversion unit 82 converts the output voltage from the charging unit 81 into a voltage for causing the display device 9 to execute the OFF sequence, and outputs the voltage to the display device 9.

  The charging voltage detection unit 83 detects the voltage of the charging unit 81 (each charging unit provided in the charging unit 81) and transmits it to the control unit 2.

  The power supply control unit 28 includes a power distribution control unit 41, an abnormality detection unit 42, and a switching control unit 46. The abnormality detection unit 42 includes a voltage drop detection unit 43, a software abnormality detection unit 44, and a battery removal operation detection unit 45.

  The power distribution control unit 41 determines the power to be supplied to each unit of the mobile device 1 according to the operation status of the mobile device 1 and supplies the determined power from the main power supply unit 10 to each unit. In addition, the distribution control unit 41 starts charging the charging unit 81 (each charging unit included in the charging unit 81) in the standby power supply unit 11, and then the voltage of the charging unit 81 detected by the charging voltage detection unit 83 is predetermined. When the charging completion voltage is reached, the power supply from the main power supply unit 10 to the charging unit 81 is stopped, and the charging of the charging unit 81 is stopped. Moreover, the power distribution control part 41 restarts the electric power supply from the main power supply part 10 to the charging part 81, when the voltage of the charging part 81 falls to the predetermined charging resumption voltage. That is, the power distribution control unit 41 repeats the start and stop of power supply to the charging unit 81 according to the voltage detection result of the charging unit 81. Note that the charging method that repeats the start and stop of the power supply to the charging unit 81 is an effective means when the withstand voltage performance is limited like a secondary battery (storage battery). When used, it may not be necessary to stop the power supply to the charging unit 81. For this reason, the charging method for the charging unit 81 is not limited to the above-described method, and may be appropriately changed according to the characteristics of the charging means provided in the charging unit 81.

  The abnormality detection unit 42 includes a voltage drop detection unit 43, a software abnormality detection unit 44, and a battery removal operation detection unit 45.

  The voltage drop detection unit 43 detects when the output voltage (or charging voltage) of the battery 71 has dropped below a predetermined voltage value preset as a voltage for starting the OFF sequence of the display device 9. In the present embodiment, the normal voltage of the battery 71 (voltage that can normally drive each part of the portable device 1) is 2.75V to 4.2V, and the predetermined voltage value is set to 2.75V. . The voltage drop detection unit 43 may detect that the output voltage of the main power supply unit 10 has dropped below a predetermined voltage value.

  The software abnormality detection unit 44 detects when a condition set in advance as a condition for starting the OFF sequence of the display device 9 occurs in various software operating in the control unit 2. Examples of the condition include occurrence of control failure of the operation of the display device 9 by the control unit 2 or occurrence of control failure of the operation of the mobile terminal 1 by the control unit 2. As a specific example, for example, the display control unit 27 generates an operation control failure of the display drive unit 31 (for example, a hang-up (freeze) in which the display control unit 27 cannot control the display state of the display unit 32). And hang-up of the entire system of the portable terminal 1 (for example, shutdown due to operation control failure of the control unit 2 due to data destruction of the storage unit 8).

  The battery removal operation detection unit 45 detects when the removal operation of the battery 71 is performed. In the present embodiment, when the operation of opening and closing the lid (not shown) of the battery storage unit that stores the battery 71 is performed, the battery removal operation detection unit 45 performs the battery 71 removal operation. It is to be detected as a thing. However, the removal operation of the battery 71 detected by the battery removal operation detection unit 45 is not limited to this. For example, the operation of removing the battery 71 itself from the portable device 1 may be performed. It may be an operation for releasing the fixing to the fixing member fixed to the head.

  The abnormality detection unit 42 only needs to detect that a predetermined condition that needs to start the OFF sequence of the display device 9 has occurred. The conditions include the voltage drop detection unit 43, the software abnormality detection unit, and the like. 44 and the above conditions detected by the battery removal operation detection unit 45 are not limited. For example, when a vibration or impact of a predetermined level or higher occurs in the mobile device 1, the abnormality detection unit 42 may detect it as a condition for starting the OFF sequence of the display device 9.

  When the abnormality detection unit 42 detects that a predetermined condition that needs to start the OFF sequence of the display device 9 has occurred, the switching control unit 46 causes the timing generator 52 and the power supply switching unit 56 of the display driving unit 31 to A power supply switching signal is sent, and the OFF sequence of the display device 9 is executed using the power supplied from the standby power supply unit 11 to the display device 9. At this time, the power supply switching unit 56 sets the connection state between the display device 9 and the standby power supply unit 11 (supply path of the standby power supply), while the display device 9 and the main power supply unit 10 (main power supply power). Supply path) is cut off. Thereby, when the OFF sequence of the display device 9 is executed using the standby power, the OFF sequence operation of the display device 9 can be performed by turning off the display device 9 and the main power supply unit 10. 1 can be prevented from affecting each part (the control unit 2 and other members) other than the display device 9 in FIG.

(1-3. Configuration of Main Power Supply Unit 10, Standby Power Supply Unit 11, and Power Supply Switching Unit 56)
FIG. 3 is an explanatory diagram showing configurations of the main power supply unit 10, the standby power supply unit 11, and the power supply switching unit 56.

  As shown in FIG. 3, the voltage conversion unit 72 of the main power supply unit 10 includes a 5.8V DCDC converter 72a, a 1.8V DCDC converter 72b, and a 20V DCDC converter 72c.

  The power supply switching unit 56 includes a changeover switch 56a and a changeover switch 56b.

  The charging unit 81 of the standby power supply unit 11 includes a capacitor 81a, a diode 81b, and a capacitor 81c. In addition, the standby power supply unit 11 includes a 1.65 V LDO (low drop out) regulator as the voltage conversion unit 82.

  In FIG. 3, the external power supply connection unit 74 of the main power supply unit 10 and the charging voltage detection unit 83 of the standby power supply unit 11 are not shown.

  The 5.8V DCDC converter 72a has an input terminal connected to the battery 71, and an output terminal connected to one end of the changeover switch 56a and one end of the diode 81b. Thereby, the 5.8V DCDC converter 72a converts the input voltage from the battery 71 into 5.8V and outputs it to the changeover switch 56a and the diode 81b.

  The other end of the changeover switch 56a is connected to the gate driver 54, the source driver 53, and the capacitor 81a. As a result, 5.8V output power from the 5.8V DCDC converter 72a is supplied to the gate driver 54 and the source driver 53 via the changeover switch 56a, and the capacitor 81a is charged.

  The changeover switch 56 a cuts off the gate driver 54, the source driver 53, and the capacitor 81 a and the main power supply unit 10 when executing the OFF sequence of the display device 9. As a result, the power stored in the capacitor 81 a is supplied to the gate driver 54 and the source driver 53.

  The other end of the diode 81b is connected to a capacitor 81c and a voltage conversion unit 82 including a 1.65V LDO. As a result, the output power of 5.8V from the 5.8V DCDC converter 72a is charged to the capacitor 81c via the diode 81b, and is also converted to 1.65V by the voltage converter (1.65V LDO) 82. . The output terminal of the voltage conversion unit (1.65V LDO) 82 is connected between the output terminal of the changeover switch 56b and the frame memory 51, the timing generator 52, and the OFF sequence storage unit 57.

  The 1.8V DCDC converter 72 b has an input terminal connected to the battery 71 and an output terminal connected to one end of the changeover switch 56 b and the control unit 2. Thereby, the 1.8V DCDC converter 72b converts the input voltage from the battery 71 into 1.8V and outputs the voltage to the changeover switch 56b and the control unit 2. In the present embodiment, the control unit 2 operates using 1.8V power supplied from the main power supply unit 10.

  The other end of the changeover switch 56b is connected to the output terminal of the voltage conversion unit (1.65V LDO) 82, the frame memory 51, the timing generator 52, and the OFF sequence storage unit 57. Thus, when the 1.8V DCDC converter 72b and the frame memory 51, the timing generator 52, and the OFF sequence storage unit 57 are connected by the changeover switch 56b, the 1.8V from the 1.8V DCDC converter 72b is connected. Output power is supplied to the frame memory 51, the timing generator 52, and the OFF sequence storage unit 57.

  In this case, since the output voltage of the voltage converter (1.65V LDO) 82 is lower than the output voltage of the 1.8V DCDC converter 72b, the output voltage of the frame memory 51, the timing generator 52, and the OFF sequence storage unit 57 is substantially reduced. Not supplied.

  Further, when executing the OFF sequence of the display device 9, the changeover switch 56 b disconnects the 1.8 V DCDC converter 72 b from the frame memory 51, the timing generator 52, and the OFF sequence storage unit 57. As a result, the electric power stored in the capacitor 81 c is converted to 1.65 V by the voltage conversion unit (1.65 V LDO) 82 and output to the frame memory 51, the timing generator 52, and the OFF sequence storage unit 57. At this time, since the capacitor 81c is connected to the 5.8V DCDC converter 72a via the diode 81b, the electric power stored in the capacitor 81c is not output to the 5.8V DCDC converter 72a side.

  In the present embodiment, when the liquid crystal display panel 61 performs normal image display using the power supplied from the main power supply unit 10, the frame memory 51, the timing generator 52, and the OFF sequence storage unit 57. Although the power of 8V is supplied, the minimum voltage for causing the frame memory 51, the timing generator 52, and the OFF sequence storage unit 57 to perform the operation of the OFF sequence is 1.65V, and the power stored in the standby power supply unit 11 When the OFF sequence is executed by using the power, 1.65 V power is supplied to the frame memory 51, the timing generator 52, and the OFF sequence storage unit 57. Thereby, the charging capacity required for the charging unit 81 of the standby power supply unit 11 can be reduced, the device configuration can be downsized, and the charging time can be shortened.

  The 20V DCDC converter 72 c has an input terminal connected to the battery 71 and an output terminal connected to the backlight driving unit 55. As a result, the 20V DCDC converter 72c converts the input voltage from the battery 71 into 20V and outputs it to the backlight drive unit 55.

(1-4. Control method of power supply to display device 9)
FIG. 4 is a flowchart showing a flow of control processing of power supply to the display device 9 in the mobile device 1.

  First, the switching control unit 46 controls the operation of the power supply switching unit 56 so as to supply output power from the main power supply unit 10 to each unit of the display device 9 when the power supply of the display device 9 is turned on (S1). (S2).

  Thereafter, the power distribution control unit 41 determines whether the charging unit 81 has been charged based on the voltage detection result of the charging unit 81 by the charging voltage detection unit 83 (whether the charging voltage of the charging unit 81 is equal to or higher than a predetermined voltage value). (S3), if charging is not completed, charging of the charging unit 81 is started (S4).

  In addition, when the time required for charging the charging unit 81 is sufficiently shorter than the display ON sequence time, which is the time required from the power-on of the display device 9 to the start of display, or the start and stop of power supply to the charging unit 81 If the charging method does not need to be repeated, the processes of S3 and S4 may be omitted. Further, when the processes of S3 and S4 are omitted, the charging voltage detector 83 may be omitted.

  When the power distribution control unit 41 determines in S3 that the charging unit 81 has been charged, the battery removal operation detection unit 45 determines whether or not the battery 71 is removed (S5).

  If it is determined in S5 that the battery 71 is not removed, the software abnormality detection unit 44 determines whether or not software abnormality has occurred (as a condition for starting the OFF sequence of the display device 9). It is determined whether or not a condition has occurred (S6).

  When it is determined in S6 that no software abnormality has occurred, the voltage drop detection unit 43 sets a predetermined voltage that is set in advance as a voltage at which the battery 71 of the main power supply unit 10 starts the OFF sequence of the display device 9. It is determined whether or not the value has fallen below the value (S7).

  If it is determined in S7 that the voltage of the battery 71 has not dropped below the predetermined voltage value (the battery 71 has not been removed, no software abnormality has occurred, and the voltage of the battery 71 has not been reached). When it is determined that the voltage does not drop below the predetermined voltage value), the control unit 2 determines whether or not to turn off the power of the display device 9 (S8). This determination may be made, for example, based on whether or not an instruction for turning off the power of the display device 9 is input from the user to the operation unit 3. The instruction input from the user to the operation unit 3 is performed for a predetermined time. If the above is not performed, it may be determined that the power is turned off.

  If it is determined in S8 that the display device 9 is not powered off, the process returns to S3.

  On the other hand, when it is determined in S8 that the power of the display device 9 is turned off, the display control unit 27 sends a control signal for executing the OFF sequence of the display device 9 to the timing generator 52 and is supplied from the main power supply unit 10. The power supply is used to execute the OFF sequence of the display device 9 (S9), and the process is terminated.

  Further, when it is determined in S5 that the battery 71 has been removed, when it is determined that a software abnormality has occurred in S6, and when it is determined in S7 that the voltage of the battery 71 has decreased to a predetermined voltage value or less. The switching control unit 46 shuts off the power supply path from the main power supply unit 10 to the display device 9 to the power supply switching unit 56 (S10), and supplies the power stored in the standby power supply unit 11 to the display device 9. A power supply switching signal for supplying (S11) is output, and an OFF sequence is executed using the power supplied from the standby power supply unit 11 to each unit of the display device 9 (S12), and the process is terminated.

  In the present embodiment, the emergency stop condition does not occur, and when the normal power OFF operation is performed, the power supply supplied from the main power supply unit 10 is used to execute the OFF sequence of the display device 9. Yes. However, the present invention is not limited to this. Even when an emergency stop condition does not occur and the normal power OFF operation is performed, the power supplied from the standby power supply unit 11 is the same as when the emergency stop condition occurs. It may be used to execute the OFF sequence of the display device 9.

(1-5. Modification Examples of Main Power Supply Unit 10, Standby Power Supply Unit 11, and Power Supply Switching Unit 56)
In the present embodiment, as shown in FIG. 3, the charging unit 81 (capacitors 81a and 81c) of the standby power supply unit 11 is charged using the output power of the 5.8V DCDC converter 72a. It is not limited to.

  For example, as shown in FIG. 5, the capacitor 81c may be charged by supplying the output power of the battery 71 to the capacitor 81c via the diode 81b.

  Further, as shown in FIG. 6, the capacitor 81c may be charged by supplying the output power of the 20V DCDC converter 72c to the capacitor 81c via the diode 81b.

  Further, as shown in FIG. 7, a capacitor 81c is connected to the output terminal of the changeover switch 56b, and the output power of the 1.8V DCDC converter 72b is supplied to the capacitor 81c via the changeover switch 56b to charge the capacitor 81c. It is good also as composition to do. In this case, the power stored in the capacitor 81c is transmitted to the frame memory 51, the timing by cutting off the 1.8V DCDC converter 72b and the frame memory 51, the timing generator 52, and the OFF sequence storage unit 57 by the changeover switch 56b. This is supplied to the generator 52 and the OFF sequence storage unit 57, and the OFF sequence is executed. Since the charging voltage of the capacitor 81c is 1.8V, the charge stored in the capacitor 81c may be supplied as it is to the frame memory 51, the timing generator 52, and the OFF sequence storage unit 57 when the OFF sequence is executed. In the example of FIG. 7, the voltage conversion unit (1.65 V LDO) 82 is omitted. Further, a changeover switch 56b is provided between the 1.8V DCDC converter 72b and the capacitor 81c, and the 1.8V DCDC converter 72b and the capacitor 81c are cut off when the OFF sequence using the precharge power is executed. Therefore, since there is no possibility that the output power from the standby power supply unit 11 affects the members other than the display device 9, the diode 81b is also omitted in the example of FIG.

  As shown in FIG. 8, in the configuration shown in FIG. 3, the voltage conversion unit (1.65V LDO) 82 is connected to the changeover switch (connection changeover unit) 56b, and the changeover switch 56b is connected to the main power supply unit 10 (1 .8V DCDC converter 72b) is supplied with output power to frame memory 51, timing generator 52, and OFF sequence storage unit 57, or output power from standby power supply unit 11 (voltage conversion unit (1.65V LDO) 82). May be switched by the changeover switch 56b to supply to the frame memory 51, the timing generator 52, and the OFF sequence storage unit 57.

  Similarly, in the configuration shown in FIG. 5 and FIG. 6, the voltage conversion unit (1.65V LDO) 82 is connected to the changeover switch (connection changeover unit) 56b, and the changeover switch 56b is connected to the main power supply unit 10 (1.8V DCDC). The output power from the converter 72b) is supplied to the frame memory 51, the timing generator 52, and the OFF sequence storage unit 57, or the output power from the standby power supply unit 11 (voltage conversion unit (1.65V LDO) 82) is used as the frame memory. 51, the timing generator 52, and the OFF sequence storage unit 57 may be switched by a changeover switch 56b.

  3, 5, or 6, the voltage conversion unit (1.65V LDO) 82 is connected to another switching switch (not shown; connection switching unit) different from the switching switch 56 b. When the power is supplied from the main power supply unit 10 to the display drive unit 31 while being connected to the display drive unit 31, the standby power supply unit 11 and the display drive unit 31 are switched to a cut-off state. When power is supplied to the display drive unit 31, the standby power supply unit 11 and the display drive unit 31 may be switched.

  In the present embodiment, the case where a capacitor is used as the charging unit provided in the charging unit 81 of the standby power supply unit 11 has been described. However, the configuration of the charging unit is not limited thereto. For example, a secondary battery (storage battery) may be used instead of the capacitor.

  FIG. 9 shows a configuration example when a secondary battery 81d is used instead of the capacitor 81c. In the example shown in this figure, the voltage conversion unit 72 includes a 3.0V LDO 72d in addition to the 5.8V DCDC converter 72a, the 1.8V DCDC converter 72b, and the 20V DCDC converter 72c.

  The 3.0V LDO 72d has an input terminal connected to the battery 71 and an output terminal connected to the input terminal of the diode 81b. The output terminal of the diode 81b is connected to the secondary battery 81d. As a result, the output power from the battery 71 is converted to 3.0V by the 3.0V LDO 72d and charged to the secondary battery 81d via the diode 81b. Further, when the 1.8V DCDC converter 72b and the frame memory 51, the timing generator 52, and the OFF sequence storage unit 57 are cut off by the changeover switch 56b, the electric power stored in the secondary battery 81d is converted into the voltage conversion unit ( The voltage is converted to 1.65 V by the 1.65 V LDO) 82 and supplied to the frame memory 51, the timing generator 52, and the OFF sequence storage unit 57.

  The output of the battery 71 is not limited to the configuration in which the secondary battery 81d is charged by converting the voltage with the 3.0V LDO 72d. For example, the output of the 5.8V DCDC converter 72a or the 20V DCDC converter 72c is output with the 3.0V LDO 72d. The voltage may be converted and the secondary battery 81d may be charged.

  Further, an external power supply (for example, a commercial power supply source, a power generation device, a power storage device, etc.) is connected to the standby power supply unit 11 and charging provided in the charging unit 81 of the standby power supply unit 11 using power supplied from the external power supply. The means (capacitor or secondary battery) may be charged.

  When a secondary battery is used as the charging means provided in the charging unit 81 of the standby power supply unit 11, there is a merit that the charging capacity can be increased. On the other hand, the problem that the withstand voltage performance is relatively low as compared with the case of using a capacitor, and There is a problem that it takes a long time to charge.

  Further, when a capacitor is used as the charging means provided in the charging unit 81 of the standby power supply unit 11, if the charging voltage is low, a capacitor to be used can be selected from a variety of capacitors that have been commercially available, and thus the cost can be reduced. On the other hand, there is a demerit that the capacity size of the capacitor required to secure the required charge capacity is increased. In addition, when a capacitor is used as the charging means provided in the charging unit 81 of the standby power supply unit 11, there is a merit that when the charging voltage is high, the capacity size of the capacitor can be reduced, while the voltage conversion unit provided in the standby power supply unit 11. There is a problem that the size of (1.65V LDO) 82 becomes large.

  Therefore, the supply voltage from each power supply source that can be selected as a power supply source for the standby power supply unit 11, the amount of power to be supplied to the display drive unit 31 when the OFF sequence is executed, and the required device size and charging time The configuration of the standby power supply unit 11 (such as a charging unit (such as a capacitor or a secondary battery) provided in the charging unit 81, a supply source of charging power for the charging unit), or the like may be changed as appropriate. That is, the type of charging means, the supply source of charging power for the charging means, and the like may be changed as appropriate so that the time required for charging, the size of the charging means, and the like can be optimized.

  Moreover, although this embodiment demonstrated the structure in which the main power supply part 10 was provided with the battery 71, it is not restricted to this, An external power supply (for example, a commercial power supply source, a power generator, an electrical storage apparatus etc.) is used as a main power supply part. It is good also as a structure which connects each part of the portable apparatus 1 using the electric power supplied from 10 and supplied from an external power supply.

(1-6. Summary)
A liquid crystal display device according to an aspect of the present invention includes a liquid crystal display panel including a plurality of pixels, and a display driving unit that drives the liquid crystal display panel by controlling a voltage applied to each pixel according to image data. A display drive unit, and a main power supply unit that supplies power for driving the liquid crystal display panel to the display drive unit, and the display drive unit applies to each pixel when the drive of the liquid crystal display panel is stopped. A liquid crystal display device that performs a charge discharge process for discharging the accumulated charge, wherein a power supply for charging the display drive unit to execute the charge discharge process and a drive for the liquid crystal display panel are An abnormality detection unit that detects occurrence of an emergency stop condition that is a predetermined condition as a condition to be stopped, and a power supply path from the main power supply unit to the display drive unit is in a conduction state and a cutoff state. A power switching unit for switching, and when the abnormality detecting unit detects the occurrence of the emergency stop condition, the power switching unit switches the power supply path to a cut-off state, and the display driving unit is connected to the standby power source unit. The charge emission process is performed using the supplied power.

  According to the above configuration, when the abnormality detection unit detects the occurrence of the emergency stop condition, the power supply switching unit switches the power supply path from the main power supply unit to the display drive unit to the cut-off state, and the display drive unit uses the standby power supply. The charge discharge process is executed using the power supplied from the unit. As a result, when the driving of the liquid crystal display panel is stopped urgently, the charge emission process can be executed using the power supplied from the standby power supply unit to the display driving unit, so that the image sticking phenomenon can be prevented from occurring. . In addition, it is possible to prevent the influence of the charge release process in the display drive unit from reaching other members that operate using the power supplied from the main power supply unit. In addition, the standby power supply unit only needs to have a configuration that can supply power necessary for causing the display driving unit to execute the charge emission process, so that the charging capability (charging capacity) of the standby power supply unit is optimized and the device is downsized. Can be achieved.

  The abnormality detection unit may detect the output voltage of the main power supply unit or a decrease in the output voltage of a battery provided in the main power supply unit to a predetermined value or less as the emergency stop condition.

  According to the above configuration, when the output voltage of the main power supply unit or the output voltage of the battery provided in the main power supply unit drops below a predetermined value, the power supply path from the main power supply unit to the display drive unit is cut off. In addition to switching to the state, it is possible to cause the display driving unit to execute the charge discharging process using the power supplied from the standby power supply unit. Accordingly, it is possible to prevent the image sticking phenomenon from occurring and to prevent the influence of the charge emission process in the display driving unit from reaching other members that operate using the power supplied from the main power supply unit.

  Further, the abnormality detection unit may be configured to detect occurrence of an operation control failure in at least one of the liquid crystal display device and an electronic device including the liquid crystal display device as the emergency stop condition.

  According to the above configuration, when an operation control failure of the liquid crystal display device or the electronic apparatus including the liquid crystal display device occurs, the power supply path from the main power supply unit to the display drive unit is switched to a cutoff state, It is possible to cause the display driving unit to execute the charge discharging process using the power supplied from the standby power supply unit. Accordingly, it is possible to prevent the image sticking phenomenon from occurring and to prevent the influence of the charge emission process in the display driving unit from reaching other members that operate using the power supplied from the main power supply unit. Note that the above-mentioned operation control failure includes an operation control failure of the display drive unit (for example, freeze of the display screen), a hang-up of the entire electronic device system (for example, destruction of data stored in the storage means, etc.) Etc.) due to shutdown.

  Further, the abnormality detection unit may be configured to detect an operation for removing a battery provided in the main power supply unit as the emergency stop condition. In addition, as operation | movement for removing said battery, the operation | movement which opens and closes the cover of the battery accommodating part in which the battery is accommodated, the operation | movement which operates the battery holding part holding the battery, and cancels | releases a holding state, for example And an operation of removing the battery.

  According to the above configuration, when an operation for removing the battery provided in the main power supply unit is performed, the power supply path from the main power supply unit to the display drive unit is switched to the cut-off state and supplied from the standby power supply unit. It is possible to cause the display driving unit to execute the charge discharging process using the generated electric power. Accordingly, it is possible to prevent the image sticking phenomenon from occurring and to prevent the influence of the charge emission process in the display driving unit from reaching other members that operate using the power supplied from the main power supply unit.

  In addition, the standby power supply unit is charged using the power supplied from the main power supply unit, and the power supply path from the main power supply unit to the standby power supply unit is connected to the standby power supply unit from the main power supply unit. A diode may be provided that allows power supply to the standby power supply unit while blocking power supply from the standby power supply unit to the main power supply unit.

  According to said structure, while being able to charge a standby power supply part using the electric power supplied from a main power supply part, it can prevent that the electric power charged by the standby power supply part flows back into a main power supply part.

  The supply voltage from the standby power supply unit to the display drive unit is lower than the supply voltage from the main power supply unit to the display drive unit, and power is supplied to the display drive unit in the standby power supply unit. The output terminal may be connected between the power supply switching unit and the display driving unit.

  According to the above configuration, when power is supplied from the main power supply unit to the display drive unit, power is not substantially supplied from the standby power supply unit to the display drive unit, and display drive is performed from the main power supply unit. A configuration in which power is supplied from the standby power supply unit to the display drive unit when the power supply to the unit is interrupted can be easily realized with a simple circuit.

  A connection switching unit that switches a power supply path from the standby power supply unit to the display driving unit between a conduction state and a cutoff state; and the connection switching unit supplies power from the main power source unit to the display driving unit. In this case, the state may be switched to the cut-off state, and when power is supplied from the standby power supply unit to the display driving unit, the state may be switched to the conductive state.

  According to the above configuration, when power is supplied from the main power supply unit to the display drive unit, power is not supplied from the standby power supply unit to the display drive unit, but from the main power supply unit to the display drive unit. A configuration in which power is supplied from the standby power supply unit to the display driving unit when the supply is interrupted can be easily realized.

  Further, the standby power supply unit may be configured to charge the power to a capacitor or a secondary battery.

  According to the above configuration, when the power supply from the main power supply unit to the display drive unit is interrupted, the display drive unit is subjected to charge discharge processing using the power charged in the capacitor or secondary battery provided in the standby power supply unit. Can be done.

  The liquid crystal display panel includes a data signal line for supplying a voltage corresponding to image data to each pixel, and one or a plurality for switching between the data signal line and the pixel between a conduction state and a cutoff state. A switching element provided for each pixel, and the switching element may be a thin film transistor element including a channel layer made of an oxide semiconductor. For example, the oxide semiconductor may contain indium, gallium, zinc, and oxygen.

  In the above configuration, since a thin film transistor element including an oxide semiconductor having a very high OFF resistance as a channel layer is used as a switching element of a pixel, when power supply is cut off without performing charge emission processing In particular, the seizure phenomenon of liquid crystal display panels is particularly likely to occur. However, according to the above configuration, even when it is difficult to supply power from the main power supply unit to the display drive unit, the charge emission processing is performed using the power supplied from the standby power supply unit to the display drive unit. It can be carried out. Thereby, it is possible to appropriately prevent the image sticking phenomenon of the liquid crystal display panel from occurring.

(1-7. Example of program)
In the present embodiment, each block of the mobile device 1, particularly the control unit 2, may be realized by hardware by a logic circuit formed on an integrated circuit (IC chip), or a CPU (Central Processing Unit) may be realized. And may be realized in software.

  In the latter case, the portable device 1 includes a CPU that executes instructions of a program that realizes each function, a ROM (Read Only Memory) that stores the program, a RAM (Random Access Memory) that expands the program, the program, and various types A storage device (recording medium) such as a memory for storing data is provided. An object of the present invention is to provide a recording medium in which a program code (execution format program, intermediate code program, source program) of a control program of the portable device 1 which is software that realizes the above-described functions is recorded in a computer-readable manner, This can also be achieved by supplying the portable device 1 and reading and executing the program code recorded on the recording medium by the computer (or CPU or MPU).

  Examples of the recording medium include non-transitory tangible medium, such as magnetic tape and cassette tape, magnetic disk such as floppy (registered trademark) disk / hard disk, and CD-ROM / MO. Discs including optical discs such as / MD / DVD / CD-R, cards such as IC cards (including memory cards) / optical cards, semiconductor memories such as mask ROM / EPROM / EEPROM (registered trademark) / flash ROM Alternatively, logic circuits such as PLD (Programmable Logic Device) and FPGA (Field Programmable Gate Array) can be used.

  Further, the portable device 1 may be configured to be connectable to a communication network, and the program code may be supplied via the communication network. The communication network is not particularly limited as long as it can transmit the program code. For example, the Internet, intranet, extranet, LAN, ISDN, VAN, CATV communication network, virtual private network, telephone line network, mobile communication network, satellite communication network, and the like can be used. The transmission medium constituting the communication network may be any medium that can transmit the program code, and is not limited to a specific configuration or type. For example, even with wired lines such as IEEE 1394, USB, power line carrier, cable TV line, telephone line, ADSL (Asymmetric Digital Subscriber Line) line, infrared rays such as IrDA and remote control, Bluetooth (registered trademark), IEEE 802.11 wireless, HDR ( It can also be used by radio such as High Data Rate (NFC), Near Field Communication (NFC), Digital Living Network Alliance (DLNA), mobile phone network, satellite line, and digital terrestrial network. The present invention can also be realized in the form of a computer data signal embedded in a carrier wave in which the program code is embodied by electronic transmission.

  The present invention is not limited to the above-described embodiments, and various modifications can be made within the scope shown in the claims. That is, embodiments obtained by combining technical means appropriately modified within the scope of the claims are also included in the technical scope of the present invention.

  The present invention can be applied to a liquid crystal display device that performs a predetermined OFF sequence (charge release process) for preventing a burn-in phenomenon of the liquid crystal display panel when the power is turned off.

1 Mobile devices (electronic devices)
2 Control unit 9 Display device 10 Main power supply unit 11 Standby power supply unit 27 Display control unit 28 Power supply control unit 31 Display drive unit 32 Display unit 41 Distribution control unit 42 Abnormality detection unit 43 Voltage drop detection unit 44 Software abnormality detection unit 45 Battery Removal operation detection unit 46 Switching control unit 51 Frame memory 52 Timing generator 53 Source driver 54 Gate driver 55 Backlight drive unit 56 Power supply switching unit 56a Changeover switch 56b Changeover switch 57 OFF sequence storage unit 61 Liquid crystal display panel 62 Backlight 71 Battery 72 Voltage converter 72a 5.8V DCDC converter 72b 1.8V DCDC converter 72c 20V DCDC converter 72d LDO
73 Voltage detection unit 74 External power supply connection unit 81 Charging unit 81a Capacitor 81b Diode 81c Capacitor 81d Secondary battery 82 Voltage conversion unit 83 Charging voltage detection unit

Claims (10)

A liquid crystal display panel having a plurality of pixels, a display driving unit for driving the liquid crystal display panel by controlling a voltage applied to each pixel according to image data, and power for driving the liquid crystal display panel And a main power supply unit that supplies the display drive unit to the display drive unit, and when the drive of the liquid crystal display panel is stopped, the display drive unit performs a charge discharge process for discharging the charges accumulated in the pixels. Because
A standby power supply unit that charges the display drive unit with electric power for executing the charge release process;
An abnormality detection unit for detecting occurrence of an emergency stop condition that is a predetermined condition as a condition for emergency stop of driving of the liquid crystal display panel;
A power supply switching unit that switches a power supply path from the main power supply unit to the display driving unit between a conduction state and a cutoff state;
When the abnormality detection unit detects the occurrence of the emergency stop condition, the power supply switching unit switches the power supply path to a cutoff state, and the display driving unit uses the power supplied from the standby power supply unit. A liquid crystal display device that performs charge discharge processing.   The abnormality detection unit detects a decrease in the output voltage of the main power supply unit or the output voltage of a battery provided in the main power supply unit to a predetermined value or less as the emergency stop condition. The liquid crystal display device described.   The said abnormality detection part detects generation | occurrence | production of the operation control failure in at least one of the said liquid crystal display device and the electronic device provided with the said liquid crystal display device as the said emergency stop conditions, The said 1 or 2 characterized by the above-mentioned. Liquid crystal display device.   4. The liquid crystal display device according to claim 1, wherein the abnormality detection unit detects an operation for removing a battery provided in the main power supply unit as the emergency stop condition. 5. The standby power supply unit is configured to be charged using power supplied from the main power supply unit,
The power supply path from the main power supply unit to the standby power supply unit is allowed to supply power from the main power supply unit to the standby power supply unit, while the power supply from the standby power supply unit to the main power supply unit is cut off. 5. The liquid crystal display device according to claim 1, further comprising a diode. The supply voltage from the standby power supply unit to the display drive unit is lower than the supply voltage from the main power supply unit to the display drive unit, and
6. The output terminal for supplying electric power to the display drive unit in the standby power supply unit is connected between the power supply switching unit and the display drive unit. 2. A liquid crystal display device according to item 1. A connection switching unit that switches a power supply path from the standby power supply unit to the display driving unit between a conduction state and a cutoff state;
The connection switching unit is switched to a cut-off state when power is supplied from the main power supply unit to the display drive unit, and is switched to a conductive state when power is supplied from the standby power supply unit to the display drive unit. The liquid crystal display device according to claim 1, wherein the liquid crystal display device is a liquid crystal display device.   The liquid crystal display device according to claim 1, wherein the standby power supply unit charges the power to a capacitor or a secondary battery. The liquid crystal display panel includes a data signal line for supplying a voltage corresponding to image data to each pixel, and one or a plurality of pixels for switching between the data signal line and the pixel between a conduction state and a cutoff state A switching element provided for each,
The liquid crystal display device according to claim 1, wherein the switching element is a thin film transistor element including a channel layer made of an oxide semiconductor.   The liquid crystal display device according to claim 9, wherein the oxide semiconductor contains indium, gallium, zinc, and oxygen.

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