WO2013024755A1 - Display device and drive method for same - Google Patents

Display device and drive method for same Download PDF

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Publication number
WO2013024755A1
WO2013024755A1 PCT/JP2012/070124 JP2012070124W WO2013024755A1 WO 2013024755 A1 WO2013024755 A1 WO 2013024755A1 JP 2012070124 W JP2012070124 W JP 2012070124W WO 2013024755 A1 WO2013024755 A1 WO 2013024755A1
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WIPO (PCT)
Prior art keywords
data signal
polarity
display device
pixel
signal line
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PCT/JP2012/070124
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French (fr)
Japanese (ja)
Inventor
齊藤　浩二
佳典 柴田
和樹 高橋
正実 尾崎
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シャープ株式会社
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Publication of WO2013024755A1 publication Critical patent/WO2013024755A1/en

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    • 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
    • G09G3/3611—Control of matrices with row and column drivers
    • G09G3/3614—Control of polarity reversal in general
    • G—PHYSICS
    • G09—EDUCATION; CRYPTOGRAPHY; DISPLAY; ADVERTISING; SEALS
    • G09G—ARRANGEMENTS OR CIRCUITS FOR CONTROL OF INDICATING DEVICES USING STATIC MEANS TO PRESENT VARIABLE INFORMATION
    • G09G2320/00—Control of display operating conditions
    • G09G2320/02—Improving the quality of display appearance
    • G09G2320/0247—Flicker reduction other than flicker reduction circuits used for single beam cathode-ray tubes
    • G—PHYSICS
    • G09—EDUCATION; CRYPTOGRAPHY; DISPLAY; ADVERTISING; SEALS
    • G09G—ARRANGEMENTS OR CIRCUITS FOR CONTROL OF INDICATING DEVICES USING STATIC MEANS TO PRESENT VARIABLE INFORMATION
    • G09G2330/00—Aspects of power supply; Aspects of display protection and defect management
    • G09G2330/02—Details of power systems and of start or stop of display operation
    • G09G2330/021—Power management, e.g. power saving

Definitions

  • the present invention relates to a display device and a driving method thereof.
  • Patent Document 1 discloses a method of performing interlaced scanning in which scanning is performed on odd lines of scanning signal lines and frames performed on even lines are alternately repeated. In this interlaced scanning, the number of lines scanned in one frame is halved compared to normal sequential scanning, so that the frequency of the horizontal synchronization signal can be kept low and power consumption can be reduced.
  • Patent Document 1 is inappropriate for displaying moving images because scanning of scanning signal lines is skipped. For example, when a pattern in a display image moves left and right, horizontal stripes are seen at the edges of the pattern, and smooth moving image display cannot be performed.
  • an object of the present invention is to provide a display device capable of reducing power consumption without lowering display quality and a driving method thereof.
  • a display device includes a plurality of scanning signal lines, a plurality of data signal lines intersecting with the plurality of scanning signal lines, the plurality of scanning signal lines, and A display panel including a pixel formed at each intersection of the plurality of data signal lines, and a driving circuit for supplying a data signal to the pixel electrode of each pixel through each of the data signal lines, and each of the plurality of frames And a drive circuit for inverting the polarity of the data signal supplied to each of the pixel electrodes.
  • a driving method of a display device includes a plurality of scanning signal lines, a plurality of data signal lines intersecting with the plurality of scanning signal lines, and the plurality of the plurality of scanning signal lines.
  • a display device having a display panel having a scanning signal line and a pixel formed at each intersection of the plurality of data signal lines, wherein data is transferred to the pixel electrode of each pixel through each data signal line.
  • the polarity of the data signal supplied to the pixel electrode through each data signal line is inverted every frame. That is, polarity inversion is performed at the same frequency as the refresh rate.
  • the polarity of the data signal supplied to each pixel electrode is inverted every plurality of frames. That is, the frequency at which the drive circuit inverts the polarity of the pixel electrode (that is, the polarity inversion frequency) is set lower than the frequency at which each scanning signal line is selected and scanned (that is, the refresh rate).
  • the power accompanying polarity inversion that is, the power accompanying charging / discharging of the pixel electrode is halved.
  • the present invention by reducing the polarity inversion frequency below the refresh rate, it is possible to reduce the power accompanying polarity inversion, that is, the power accompanying charging / discharging of the pixel electrode. Therefore, power consumption in the display device can be reduced. At this time, since the display device does not lower the refresh rate or perform interlaced scanning, power consumption can be reduced without lowering the display quality.
  • the polarity inversion frequency of the pixel electrode in the display device is lower than the refresh rate
  • the power accompanying polarity inversion that is, the power accompanying charging / discharging of the pixel electrode can be reduced. Therefore, power consumption in the display device can be reduced.
  • the display device does not lower the refresh rate or perform interlaced scanning, power consumption can be reduced without lowering the display quality.
  • (A) in the figure is a structural diagram showing a pixel array in a conventional display panel
  • (b) in the figure is a structural diagram showing a pixel array in a display panel according to an embodiment of the present invention.
  • It is a block diagram which shows the detail of a structure of the display system which concerns on one Embodiment of this invention.
  • (A) in the figure is a structural diagram showing a pixel array in a conventional display panel
  • (b) in the figure is a structural diagram showing a pixel array in a display panel according to an embodiment of the present invention.
  • (A) in the figure is a structural diagram showing a pixel array in a conventional display panel
  • (b) in the figure is a structural diagram showing a pixel array in a display panel according to an embodiment of the present invention. It is a figure which shows the graph showing the relationship between drain current Idd and the gate-on voltage Vgh.
  • (A) in the figure is a diagram showing a cross section of one pixel of a horizontal electric field type liquid crystal display device
  • (b) in the figure is a diagram showing a cross section of one pixel of a vertical electric field type liquid crystal display device. is there.
  • FIG. 2 is a block diagram showing details of the configuration of the display system 1 according to the present embodiment.
  • the display system 1 includes a display device 2 and a control unit 3.
  • the control unit 3 displays and outputs an image via the display device 2.
  • the polarity inversion frequency in the display device 2 is controlled.
  • the above control can be performed by the control unit 3 or the timing control unit 7 of the display device 2.
  • the control unit 3 may display and output arbitrary information such as still images or symbols in addition to the video via the display device 2.
  • the display device 2 includes a display panel 2a, a scanning line driving circuit 4, a signal line driving circuit 5 (driving circuit), a common electrode driving circuit 6, and a timing control unit 7.
  • the display panel 2a includes a screen made up of a plurality of pixels arranged in a matrix. Further, the display panel 2a includes N (N is an arbitrary integer) scanning signal lines G (gate lines) for selecting and scanning the screen in a line-sequential manner. Further, the display panel 2a includes M (M is an arbitrary integer) data signal lines S (source lines) that supply data signals to pixels for one row included in the selected line. The scanning signal line G and the data signal line S cross each other.
  • G (n) shown in FIG. 2 represents the n-th scanning signal line G (n is an integer from 1 to N).
  • G (1), G (2), and G (3) represent the first, second, and third scanning signal lines G, respectively.
  • S (m) represents the m-th data signal line S (m is an integer from 1 to M).
  • S (1), S (2), and S (3) represent the first, second, and third data signal lines S, respectively.
  • the scanning line driving circuit 4 sequentially scans each scanning signal line G from the top to the bottom of the screen, for example. At that time, for each scanning signal line G, a rectangular wave for turning on a switching element (pixel thin film transistor (TFT)) provided in the pixel and connected to the pixel electrode is output. Thereby, the pixels for one row in the screen are selected.
  • a switching element pixel thin film transistor (TFT)
  • the signal line drive circuit 5 calculates the value of the voltage to be output to each pixel for the selected row from the video signal (arrow A) input from the control unit 3, and the voltage of that value (data signal) Is output to each data signal line S. As a result, image data is supplied to the pixel electrode of each pixel on the selected scanning signal line G.
  • the display device 2 includes a common electrode (not shown) provided for each pixel in the screen.
  • the common electrode drive circuit 6 outputs a predetermined common voltage for driving the common electrode to the common electrode based on the signal (arrow B) input from the timing control unit 7 (arrow C).
  • the timing control unit 7 Based on the clock signal, the horizontal synchronization signal, and the vertical synchronization signal (arrow D) input from the control unit 3, the timing control unit 7 provides each circuit with a signal that serves as a reference for each circuit to operate in synchronization. Output. Specifically, the gate start pulse signal GSP, the gate clock signal GCK, and the gate output enable signal GOE are output to the scanning line driving circuit 4 based on the clock signal, the horizontal synchronization signal, and the vertical synchronization signal. (Arrow E). A source start pulse signal SSP, a source latch strobe signal SLS, and a source clock signal SCK are output to the signal line driver circuit 5 based on the clock signal, the horizontal synchronization signal, and the vertical synchronization signal (arrow F).
  • the scanning line driving circuit 4 starts scanning the display panel 2a with the gate start pulse signal GSP received from the timing control section 7 as a cue, and shifts the selection state of the scanning signal line G, which is a gate clock signal GCK.
  • the selection voltage is sequentially applied to each scanning signal line G.
  • the signal line drive circuit 5 Based on the source start pulse signal SSP received from the timing control unit 7, stores the input image data of each pixel in a register according to the source clock signal SCK. Then, after storing the image data, the signal line driving circuit 5 writes the image data to the pixel electrode through each data signal line S of the display panel 2a in accordance with the next source latch strobe signal SLS.
  • an analog amplifier included in the signal line driving circuit 5 is used for writing the image data.
  • the voltage necessary for the operation of each circuit in the display system 1 is supplied from, for example, a power generation circuit (not shown), but this power generation circuit may be included in the control unit 3.
  • the power supply voltage Vdd is supplied to the signal line driving circuit 5.
  • control of polarity reversal frequency In order to prevent flicker, it is desirable to invert the polarity of the voltage for each pixel electrode arranged in at least one of the direction of the scanning signal line G and the direction of the data signal line S. Therefore, the display device 2 performs polarity inversion driving for inverting the polarity of the voltage for each pixel electrode.
  • the control unit 3 or the timing control unit 7 controls the polarity inversion frequency in the display device 2. Specifically, for example, when the control unit 3 performs control, a control signal (arrow D) including setting information of the polarity inversion frequency is input from the control unit 3 to the polarity inversion frequency control unit 8 included in the timing control unit 7. Is done.
  • the control signal including the setting information of the polarity inversion frequency is an instruction signal that instructs the polarity inversion frequency of the pixel electrode in the display device 2 to be a predetermined frequency.
  • the polarity reversal frequency control unit 8 sets the polarity reversal frequency to the predetermined frequency based on the control signal from the control unit 3. Specifically, the polarity inversion frequency control unit 8 controls the polarity of the voltage applied to the pixel electrode from the signal line drive circuit 5 through each data signal line S based on the control signal from the control unit 3, thereby The inversion frequency is controlled.
  • the polarity inversion frequency setting information (arrow D) is input from the control unit 3 to the timing control unit 7.
  • the polarity inversion frequency setting information is information on a predetermined frequency set to the polarity inversion frequency of the pixel electrode in the display device 2.
  • the timing control unit 7 performs processing for setting the polarity inversion frequency of the pixel electrode in the display device 2 to a predetermined frequency based on the setting information from the control unit 3. Specifically, the timing control unit 7 generates an instruction signal for instructing the polarity inversion frequency of the pixel electrode in the display device 2 to be a predetermined frequency based on the setting information from the control unit 3. To enter. Then, the polarity inversion frequency control unit 8 controls the polarity of the voltage applied from the signal line driving circuit 5 to the pixel electrode through each data signal line S based on the input instruction signal, thereby setting the polarity inversion frequency to the above-described value. A predetermined frequency is set.
  • the predetermined frequency is a frequency that can be arbitrarily set, but is at least a frequency lower than the refresh rate in the display device 2.
  • the polarity inversion of the pixel electrode in the display device 2 is performed, for example, the polarity inversion frequency of the pixel electrode is set to a frequency lower than the refresh rate and then set to a frequency higher than the refresh rate.
  • the frequency can be switched as appropriate. Therefore, the predetermined frequency is not necessarily a frequency lower than the refresh rate.
  • FIG. 1A is a structural diagram showing a pixel array in a conventional display panel
  • FIG. 1B is a structural diagram showing a pixel array in the display panel 2a.
  • the polarity of the voltage of each pixel electrode in the mth frame to the m + 3th frame is shown.
  • the polarity of the voltage of each pixel electrode is indicated by + (plus) and-(minus) in the figure.
  • the conventional dot inversion driving inverts the polarity of the voltage applied to each adjacent data signal line S and the polarity of the data signal applied to the data signal line S.
  • the polarity of the data signal applied to the pixel electrode is also reversed. Specifically, when the first scanning signal line G is driven in the m-th frame, paying attention to the sub-pixel R, the polarity of the voltage applied to each pixel electrode is set to the first plus (+), and the following order. Is inverted.
  • the polarity of the voltage applied to each pixel electrode is set to minus ( ⁇ ) in the first order, and is inverted in the following order.
  • the subpixels adjacent to each other in the direction of the scanning signal line G and the direction of the data signal line S are shown in FIG.
  • the polarity of the voltage between the R pixel electrodes can be made different.
  • the sub-pixel G and the sub-pixel B are driven in the same manner, but it is preferable that the polarities of the voltages of the pixel electrodes of the adjacent sub-pixels are also different in the sub-pixel RGB.
  • the polarity of the voltage opposite to that of the mth frame is applied to each pixel electrode for each scanning signal line G.
  • the polarity of the voltage applied to each pixel electrode is set to minus ( ⁇ ), and the order is inverted in the following order.
  • the second scanning signal line G is driven, paying attention to the sub-pixel R, the polarity of the voltage applied to each pixel electrode is changed to the plus (+), and the order is inverted in the following order. The same is repeated when the third and subsequent scanning signal lines G are driven.
  • the polarity of the voltage applied to each pixel electrode is inverted for each scanning signal line G. Therefore, in the conventional dot inversion drive, the polarity of the voltage of each pixel electrode is inverted for each frame. That is, polarity inversion is performed at the same frequency as the refresh rate.
  • the polarity of the data signal applied to each data signal line S is inverted for each scanning signal line G as in the conventional dot inversion driving.
  • the polarity of the data signal applied to the pixel electrode is also reversed.
  • the polarity inversion frequency control unit 8 controls so that the polarity of the voltage applied to each pixel electrode is not inverted when the mth frame is changed to the (m + 1) th frame.
  • the polarity of the voltage applied to each pixel electrode is set to the first plus (+), and the following order. Is inverted.
  • the polarity of the voltage applied to each pixel electrode is set to the plus (+). These are reversed in order.
  • the polarity of the voltage opposite to that of the (m + 1) th frame and the (m + 1) th frame is applied to each pixel electrode for each scanning signal line G.
  • the polarity of the voltage applied to each pixel electrode is set to minus ( ⁇ ) in the first order, and is inverted in the following order.
  • the polarity of the voltage applied to each pixel electrode is set to minus ( ⁇ ).
  • the polarity of the voltage of each pixel electrode is not inverted when the transition from the mth frame to the m + 1th frame is performed, and the polarity of the voltage of each pixel electrode is inverted when the transition from the (m + 1) th frame to the m + 2th frame. ing.
  • the polarity of the voltage of each pixel electrode is not inverted, and the same is repeated thereafter. Therefore, in this embodiment, the polarity of the voltage of each pixel electrode is inverted every plural frames (two frames in the case of FIG. 1). That is, polarity inversion is performed at a frequency lower than the refresh rate.
  • the power accompanying polarity inversion that is, the power accompanying charging / discharging of the pixel electrode is halved.
  • the polarity inversion frequency lower than the refresh rate, it is possible to reduce the power accompanying polarity inversion, that is, the power accompanying charging / discharging of the pixel electrode. Therefore, power consumption in the display device 2 can be reduced. At this time, since the display device 2 does not lower the refresh rate or perform interlaced scanning, power consumption can be reduced without lowering the display quality.
  • the polarity of the voltage of each pixel electrode is inverted every two frames.
  • the polarity of the voltage of each pixel electrode may be inverted every three or more frames. There is no. Therefore, the polarity inversion frequency can be set to an arbitrary frequency as long as it is lower than the refresh rate.
  • FIG. 3A is a structural diagram showing a pixel array in a conventional display panel
  • FIG. 3B is a structural diagram showing a pixel array in the display panel 2a.
  • the polarity of the voltage of each pixel electrode in the mth frame to the m + 3th frame is shown.
  • the polarity of the voltage of each pixel electrode is indicated by + (plus) and-(minus) in the figure.
  • the conventional source inversion driving is one in which data signals having the same polarity are supplied to the data signal lines S in each frame through the frame period.
  • the polarity of the voltage applied to each data signal line S is the first plus (+), and the following order Is inverted.
  • FIG. 3A the voltage of each pixel electrode arranged in the direction of the scanning signal line G is maintained with the voltage of the pixel electrode arranged in the direction of the data signal line S having the same polarity.
  • the polarity can be reversed.
  • the sub-pixel G and the sub-pixel B are driven in the same manner, but it is preferable that the polarities of the voltages of the pixel electrodes of the adjacent sub-pixels are also different in the sub-pixel RGB.
  • the polarity of the voltage opposite to that of the mth frame is applied to each data signal line S.
  • the polarity of the voltage applied to each data signal line S is set to plus (+), and is inverted in the following order. .
  • the polarity of the voltage applied to each data signal line S is similarly reversed. Therefore, in the conventional source inversion drive, the polarity of the voltage of each pixel electrode is inverted every frame. That is, polarity inversion is performed at the same frequency as the refresh rate.
  • the data signal having the same polarity is supplied to each data signal line S in each frame through the frame period as in the conventional source inversion driving.
  • the polarity inversion frequency control unit 8 controls so that the polarity of the voltage applied to each data signal line S is not inverted when the mth frame is changed to the (m + 1) th frame.
  • the polarity of the voltage applied to each data signal line S is set to the plus (+), and the following order. Is inverted.
  • the polarity of the voltage applied to each data signal line S is set to the plus (+). These are reversed in order.
  • the polarity of the voltage opposite to that of the (m + 1) th frame and the (m + 1) th frame is applied to each data signal line S.
  • the polarity of the voltage applied to each data signal line S is negative ( ⁇ ), and is inverted in the following order. .
  • the polarity of the voltage of each pixel electrode is not inverted when changing from the mth frame to the m + 1th frame, and the polarity of the voltage of each pixel electrode is inverted when changing from the m + 1th frame to the m + 2th frame.
  • the polarity of the voltage of each pixel electrode is not inverted, and the same is repeated thereafter. Therefore, in this embodiment, the polarity of the voltage of each pixel electrode is inverted every plurality of frames (two frames in the case of FIG. 3). That is, polarity inversion is performed at a frequency lower than the refresh rate.
  • the power accompanying polarity inversion that is, the power accompanying charging / discharging of the pixel electrode is halved.
  • the polarity inversion frequency lower than the refresh rate, it is possible to reduce the power accompanying polarity inversion, that is, the power accompanying charging / discharging of the pixel electrode. Therefore, power consumption in the display device 2 can be reduced. Furthermore, since the source inversion drive is performed in this embodiment, the polarity inversion frequency in each data signal line S can also be lowered. Therefore, the power accompanying polarity inversion in each data signal line, that is, the power accompanying charging / discharging of each data signal line can also be reduced, so that the power consumption in the display device 2 can be further reduced. At this time, since the display device 2 does not lower the refresh rate or perform interlaced scanning, power consumption can be reduced without lowering the display quality.
  • the polarity of the voltage of each pixel electrode is inverted every two frames.
  • the polarity inversion frequency may be set to any frequency as long as the frequency is lower than the refresh rate. Needless to say, you can.
  • the polarity of the voltage applied to each adjacent data signal line S is inverted, but the present invention is not necessarily limited to this.
  • the polarity of the voltage applied to each of the plurality of adjacent data signal lines S may be reversed, and there is no particular limitation.
  • a data signal having the same polarity may be applied to all the data signal lines S and the polarity may be inverted in units of a plurality of frames.
  • FIG. 4A is a structural diagram showing a pixel array in a conventional display panel
  • FIG. 4B is a structural diagram showing a pixel array in the display panel 2a.
  • the polarity of the voltage of each pixel electrode in the mth frame to the m + 3th frame is shown.
  • the polarity of the voltage of each pixel electrode is indicated by + (plus) and-(minus) in the figure.
  • the conventional Z-inv inversion drive is the same source inversion drive as (a) of FIG. 3, but the pixel electrode is compared with (a) of FIG. The arrangement is different.
  • a voltage is supplied to a pixel electrode in an arbitrary pixel column of the display panel 2a from a data signal line S positioned on one side (left side in the drawing) with respect to the pixel electrode.
  • the data signal located on one side (left side in the figure) of the pixel electrode of the odd-numbered row in the arbitrary pixel column of the display panel 2a with respect to the pixel electrode.
  • a voltage is supplied from the line S, and the voltage is supplied from the data signal line S located on the other side (right side in the drawing) to the pixel electrode in the even-numbered row in the arbitrary pixel column. Have been supplied. In other words, the voltage is supplied from the same data signal line S to the pixel electrodes in the odd rows in the arbitrary pixel columns and the pixel electrodes in the even rows in the pixel columns adjacent to the arbitrary pixel columns. . For this reason, in the arrangement of FIG. 3A, the polarities of the voltages of the pixel electrodes arranged between the adjacent data signal lines S are the same. However, in the arrangement of FIG. 4A, the polarities of the voltages of the pixel electrodes arranged between the adjacent data signal lines S are staggered.
  • source inversion driving is performed, but when viewed from the polarity of the voltage of the pixel electrode, it seems that dot inversion driving is performed.
  • Z-inv inversion driving there is an advantage that display quality can be improved.
  • the polarity of the voltage applied to each data signal line S is the first plus (+), and the following order Is inverted.
  • the voltage of each pixel electrode arranged in the direction of the scanning signal line G is maintained with the voltage of the pixel electrode arranged in the direction of the data signal line S having the same polarity.
  • the polarity can be reversed.
  • the sub-pixel G and the sub-pixel B are driven in the same manner, but it is preferable that the polarities of the voltages of the pixel electrodes of the adjacent sub-pixels are also different in the sub-pixel RGB.
  • the polarity of the voltage opposite to that of the mth frame is applied to each data signal line S.
  • the polarity of the voltage applied to each data signal line S is negative ( ⁇ ), and is inverted in the following order. .
  • the polarity of the voltage applied to each data signal line S is reversed. Therefore, in the conventional source inversion drive, the polarity of the voltage of each pixel electrode is inverted every frame. That is, polarity inversion is performed at the same frequency as the refresh rate.
  • the polarity of the voltage applied to each data signal line S is not reversed when changing from the mth frame to the (m + 1) th frame.
  • the polarity reversal frequency control unit 8 controls. Specifically, in driving the scanning signal lines G in the m-th frame, paying attention to the sub-pixel R, the polarity of the voltage applied to each data signal line S is set to the plus (+), and the following order. Is inverted. In the subsequent m + 1th frame, similarly to the mth frame, when the scanning signal line G is driven, when attention is paid to the subpixel R, the polarity of the voltage applied to each data signal line S is set to the plus (+). These are reversed in order.
  • the polarity of the voltage opposite to that of the (m + 1) th frame and the (m + 1) th frame is applied to each data signal line S.
  • the polarity of the voltage applied to each data signal line S is negative ( ⁇ ), and is inverted in the following order.
  • the polarity of the voltage applied to each data signal line S is set to minus ( ⁇ ).
  • the polarity of the voltage of each pixel electrode is not inverted when changing from the mth frame to the m + 1th frame, and the polarity of the voltage of each pixel electrode is inverted when changing from the m + 1th frame to the m + 2th frame.
  • the polarity of the voltage of each pixel electrode is not inverted, and the same is repeated thereafter. Therefore, in this embodiment, the polarity of the voltage of each pixel electrode is inverted every plural frames (two frames in the case of FIG. 4). That is, polarity inversion is performed at a frequency lower than the refresh rate.
  • the power accompanying polarity inversion that is, the power accompanying charging / discharging of the pixel electrode is halved.
  • the polarity inversion frequency lower than the refresh rate, it is possible to reduce the power accompanying polarity inversion, that is, the power accompanying charging / discharging of the pixel electrode. Therefore, power consumption in the display device 2 can be reduced. Furthermore, since the source inversion drive is performed in this embodiment, the polarity inversion frequency in each data signal line can also be lowered. Therefore, the power accompanying polarity inversion in each data signal line, that is, the power accompanying charging / discharging of each data signal line can also be reduced, so that the power consumption in the display device 2 can be further reduced. At this time, since the display device 2 does not lower the refresh rate or perform interlaced scanning, power consumption can be reduced without lowering the display quality. In particular, since Z-inv inversion driving is performed, display quality can be improved.
  • the polarity of the voltage of each pixel electrode is inverted every two frames.
  • the polarity inversion frequency may be set to any frequency as long as the frequency is lower than the refresh rate. Needless to say, you can.
  • amorphous silicon or low-temperature polysilicon As the semiconductor layer of the TFT of each pixel, amorphous silicon or low-temperature polysilicon (LTPS) can be used.
  • LTPS low-temperature polysilicon
  • an oxide semiconductor is used as the TFT.
  • the oxide semiconductor is, for example, IGZO (InGaZnOx).
  • FIG. 5 shows a graph showing the relationship between the drain current Idd and the gate-on voltage Vgh.
  • FIG. 5 shows the characteristics of a TFT using an oxide semiconductor, a TFT using a-Si (amorphous silicon), and a TFT using LTPS (Low Temperature PolyPolysilicon).
  • the horizontal axis (Vgh) indicates the voltage value of the on-voltage supplied to the gate in each TFT
  • the vertical axis (Id) indicates the amount of current between the source and drain in each TFT.
  • a period indicated as “TFT-on” in the figure indicates a period in which the transistor is on according to the voltage value of the on-voltage
  • a period indicated as “TFT-off” in the figure Indicates a period in which it is in an OFF state according to the voltage value of the ON voltage.
  • the amount of current (ie, electron mobility) in the off state is higher than that of a TFT using a-Si and LTPS. Low. From this, it can be seen that a TFT using an oxide semiconductor has significantly smaller off-leakage at the time of TFT-off and extremely excellent off characteristics than a TFT using a-Si and LTPS. For this reason, if an oxide semiconductor is used as the TFT, the pixel electrode is easy to hold current, which is suitable for low-frequency driving. Therefore, since the refresh rate can be easily lowered to 30 Hz or less, further reduction in power consumption can be expected.
  • a TFT using an oxide semiconductor has a higher amount of current (that is, electron mobility) in an on state than a TFT using a-Si.
  • a TFT using an oxide semiconductor has an electron mobility about 20 to 50 times higher in an on state than a TFT using a-Si, and has excellent on characteristics. I understand. Therefore, compared to amorphous silicon, it is easier to supply power to the pixel electrode and the on-characteristic is better. Therefore, when an oxide semiconductor is used as the TFT, the refresh rate can be easily increased to 60 Hz or higher, and thus high frequency driving can be realized while suppressing power consumption.
  • the display panel 2a described above may be a liquid crystal panel including a liquid crystal layer.
  • the display device 2 is a liquid crystal display device.
  • the electric field application method of the liquid crystal display device includes a horizontal electric field method that applies a horizontal electric field, such as an IPS (In Plane Switching) method, and a vertical electric field method that applies a vertical electric field, such as a VA (Vertical Alignment) method. is there.
  • FIG. 6A shows a cross-sectional view of one pixel X of a horizontal electric field type liquid crystal display device
  • FIG. 6B shows a cross-sectional view of one pixel Y of a vertical electric field type liquid crystal display device.
  • the pixel electrode 9 and the common electrode 11 are provided on one inner surface side of the pair of substrates 13 disposed with the liquid crystal layer interposed therebetween as an insulating layer. 12 is provided with insulation, and a horizontal electric field is applied.
  • the transverse electric field method has a structure in which it is difficult to lower the polarity inversion frequency.
  • the vertical electric field method as shown in FIG. 6B, a liquid crystal layer is sandwiched between the substrate 13 having the pixel electrode 9 and the substrate 13 having the common electrode 11, and the vertical electric field method is used. An electric field is applied.
  • the lines of electric force 10 are uniformly distributed, and the electric field strength in the liquid crystal layer is substantially uniform. Therefore, impurities in the liquid crystal are difficult to adhere to the pixel electrode 9.
  • the vertical electric field method has a structure in which the polarity inversion frequency can be easily increased. Therefore, the liquid crystal display device according to this embodiment is preferably a vertical electric field type.
  • a display device includes a plurality of scanning signal lines, a plurality of data signal lines intersecting with the plurality of scanning signal lines, and the plurality of the plurality of scanning signal lines.
  • a driving panel for supplying a data signal to a pixel electrode of each pixel through each data signal line, and a display panel having a pixel formed at each intersection of the plurality of scanning signal lines and the plurality of data signal lines.
  • a drive circuit for inverting the polarity of the data signal supplied to each pixel electrode for each of a plurality of frames.
  • a driving method of a display device includes a plurality of scanning signal lines, a plurality of data signal lines intersecting with the plurality of scanning signal lines, and the plurality of the plurality of scanning signal lines.
  • a display device having a display panel having a scanning signal line and a pixel formed at each intersection of the plurality of data signal lines, wherein data is transferred to the pixel electrode of each pixel through each data signal line.
  • the polarity of the data signal supplied to the pixel electrode through each data signal line is inverted every frame. That is, polarity inversion is performed at the same frequency as the refresh rate.
  • the polarity of the data signal supplied to each pixel electrode is inverted every plurality of frames. That is, the frequency at which the drive circuit inverts the polarity of the pixel electrode (that is, the polarity inversion frequency) is set lower than the frequency at which each scanning signal line is selected and scanned (that is, the refresh rate).
  • the power accompanying polarity inversion that is, the power accompanying charging / discharging of the pixel electrode is halved.
  • the present invention by reducing the polarity inversion frequency below the refresh rate, it is possible to reduce the power accompanying polarity inversion, that is, the power accompanying charging / discharging of the pixel electrode. Therefore, power consumption in the display device can be reduced. At this time, since the display device does not lower the refresh rate or perform interlaced scanning, power consumption can be reduced without lowering the display quality.
  • the drive circuit supplies the data signal having the same polarity to each data signal line in each frame throughout the frame period.
  • the polarity inversion frequency in each data signal line can also be lowered. Therefore, the power accompanying polarity inversion in each data signal line, that is, the power accompanying charging / discharging of each data signal line can be reduced, so that the power consumption in the display device can be further reduced.
  • the odd-numbered pixel electrodes in an arbitrary pixel column of the display panel and the even-numbered pixel electrodes in a pixel column adjacent to the arbitrary pixel column are provided. Is characterized in that the data signal is supplied from the same data signal line.
  • the pixel includes a thin film transistor, and an oxide semiconductor is used for a semiconductor layer of the thin film transistor.
  • the oxide semiconductor is preferably IGZO.
  • An oxide semiconductor eg, IGZO
  • TFT thin film transistor
  • LTPS low-temperature polysilicon
  • an oxide semiconductor is easier to supply power to the pixel electrode than an amorphous silicon and has better on-characteristics. Therefore, when an oxide semiconductor is used as the TFT, the refresh rate can be easily increased to 60 Hz or higher, and thus high frequency driving can be realized while suppressing power consumption.
  • examples of the display device according to one embodiment of the present invention include a liquid crystal display device.
  • the liquid crystal display device is preferably a vertical electric field type liquid crystal display device.
  • the horizontal electric field method there are a portion where the electric lines of force are sparse (a portion where the electric field strength is weak) and a portion where the electric lines of force are dense (a portion where the electric field strength is strong), and the electric field strength in the liquid crystal layer is not uniform.
  • the polarity inversion frequency which is AC driving
  • the vertical electric field method the lines of electric force are uniformly distributed, and the electric field strength in the liquid crystal layer is almost uniform.
  • the display device according to the present invention achieves a reduction in power consumption without lowering the display quality of the display device by lowering the polarity inversion frequency below the refresh rate. It can be applied to any display device.

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Abstract

A display device of one aspect of this invention performs display by supplying a data signal to each pixel electrode through each data signal line. When this occurs, the polarity of the data signal supplied to each pixel electrode is inverted for each of a plurality of frames.

Description

表示装置およびその駆動方法Display device and driving method thereof
　本発明は、表示装置およびその駆動方法に関するものである。 The present invention relates to a display device and a driving method thereof.
　近年、液晶表示装置に代表される薄型、軽量、および低消費電力の表示装置が盛んに活用されている。こうした表示装置は、例えば携帯電話機、スマートフォン、またはラップトップ型ＰＣ（Personal Computer）等への搭載が顕著である。また、今後はより薄型の表示装置である電子ペーパーの開発および普及も急速に進むことが期待されている。このような状況の中、現在、各種の表示装置において消費電力を低下させることが共通の課題となっている。 In recent years, thin, lightweight, and low power consumption display devices typified by liquid crystal display devices have been actively used. Such a display device is remarkably mounted on, for example, a mobile phone, a smart phone, or a laptop PC (Personal Computer). In the future, electronic paper, which is a thinner display device, is expected to develop and spread rapidly. Under such circumstances, it is currently a common problem to reduce power consumption in various display devices.
　各種の表示装置における消費電力を低下させるために、表示装置のリフレッシュレートを下げる方法が従来から用いられている。リフレッシュレートを下げることによって、表示装置の書き込み回数が減るので、書き込みに要する電力を抑えることができる。 In order to reduce the power consumption in various display devices, a method of reducing the refresh rate of the display device has been conventionally used. By reducing the refresh rate, the number of writing times of the display device is reduced, so that power required for writing can be suppressed.
　また、リフレッシュレートを下げる方法以外にも、他の方法で表示装置の消費電力を低下させる試みがなされている。例えば、特許文献１には、走査を走査信号線の奇数ラインにおいて行うフレームと、偶数ラインにおいて行うフレームとを交互に繰り返す飛び越し走査を行う方法が開示されている。この飛び越し走査では、１フレーム内で走査するライン数が通常の順次走査と比較して半分となるので、水平同期信号の周波数を低く抑えることができ、消費電力を低減することができる。 In addition to the method of lowering the refresh rate, attempts have been made to reduce the power consumption of the display device by other methods. For example, Patent Document 1 discloses a method of performing interlaced scanning in which scanning is performed on odd lines of scanning signal lines and frames performed on even lines are alternately repeated. In this interlaced scanning, the number of lines scanned in one frame is halved compared to normal sequential scanning, so that the frequency of the horizontal synchronization signal can be kept low and power consumption can be reduced.
日本国公開特許公報「特開２００４－２８７０８７号公報（２００４年１０月１４日公開）」Japanese Patent Publication “Japanese Patent Laid-Open No. 2004-287087 (published on October 14, 2004)”
　しかしながら、リフレッシュレートを下げると、フリッカの発生がしたり、動画表示が不自然になったりする等の問題がある。 However, if the refresh rate is lowered, there are problems such as occurrence of flicker and unnatural video display.
　また、特許文献１に開示されている方法では、走査信号線の走査を飛び越して行うため、動画表示には不適切である。例えば、表示画像中の模様が左右に動く場合、その模様のエッジで横縞が見えてしまい、滑らかな動画表示を行うことができない。 Also, the method disclosed in Patent Document 1 is inappropriate for displaying moving images because scanning of scanning signal lines is skipped. For example, when a pattern in a display image moves left and right, horizontal stripes are seen at the edges of the pattern, and smooth moving image display cannot be performed.
　そこで、本発明は上記の課題に鑑みてなされたものであり、その目的は、表示品位を下げずに消費電力を低減することができる表示装置およびその駆動方法を提供することにある。 Therefore, the present invention has been made in view of the above problems, and an object of the present invention is to provide a display device capable of reducing power consumption without lowering display quality and a driving method thereof.
　本発明の一態様に係る表示装置は、上記の課題を解決するために、複数の走査信号線と、上記複数の走査信号線と交差する複数のデータ信号線と、上記複数の走査信号線および上記複数のデータ信号線の各交差点に形成された画素とを備えた表示パネルと、各上記データ信号線を通して各上記画素の画素電極にデータ信号を供給する駆動回路であって、複数のフレームごとに、各上記画素電極に供給する上記データ信号の極性を反転させる駆動回路とを備えていることを特徴としている。 In order to solve the above problems, a display device according to one embodiment of the present invention includes a plurality of scanning signal lines, a plurality of data signal lines intersecting with the plurality of scanning signal lines, the plurality of scanning signal lines, and A display panel including a pixel formed at each intersection of the plurality of data signal lines, and a driving circuit for supplying a data signal to the pixel electrode of each pixel through each of the data signal lines, and each of the plurality of frames And a drive circuit for inverting the polarity of the data signal supplied to each of the pixel electrodes.
　また、本発明の一態様に係る表示装置の駆動方法は、上記の課題を解決するために、複数の走査信号線と、上記複数の走査信号線と交差する複数のデータ信号線と、上記複数の走査信号線および上記複数のデータ信号線の各交差点に形成された画素とを備えた表示パネルを有する表示装置の駆動方法であって、各上記データ信号線を通して各上記画素の画素電極にデータ信号を供給する駆動ステップであって、複数のフレームごとに、各上記画素電極に供給する上記データ信号の極性を反転させる駆動ステップを含んでいることを特徴としている。 In order to solve the above problems, a driving method of a display device according to one embodiment of the present invention includes a plurality of scanning signal lines, a plurality of data signal lines intersecting with the plurality of scanning signal lines, and the plurality of the plurality of scanning signal lines. A display device having a display panel having a scanning signal line and a pixel formed at each intersection of the plurality of data signal lines, wherein data is transferred to the pixel electrode of each pixel through each data signal line. A driving step of supplying a signal, the driving step including inverting the polarity of the data signal supplied to each of the pixel electrodes for each of a plurality of frames.
　従来のドット反転駆動では、フレームごとに各データ信号線を通して画素電極に供給するデータ信号の極性を反転させている。すなわち、リフレッシュレートと同じ周波数で極性反転を行っている。しかし、本発明の一態様によれば、複数のフレームごとに各画素電極に供給するデータ信号の極性を反転させている。すなわち、駆動回路が画素電極の極性を反転させる周波数（すなわち極性反転周波数）を、各走査信号線を選択して走査する周波数（すなわちリフレッシュレート）よりも低くしている。したがって、例えばリフレッシュレートが６０Ｈｚであり、極性反転周波数をリフレッシュレートの半分の３０Ｈｚとした場合、極性反転に伴う電力、すなわち画素電極の充放電に伴う電力が半減する。 In the conventional dot inversion drive, the polarity of the data signal supplied to the pixel electrode through each data signal line is inverted every frame. That is, polarity inversion is performed at the same frequency as the refresh rate. However, according to one aspect of the present invention, the polarity of the data signal supplied to each pixel electrode is inverted every plurality of frames. That is, the frequency at which the drive circuit inverts the polarity of the pixel electrode (that is, the polarity inversion frequency) is set lower than the frequency at which each scanning signal line is selected and scanned (that is, the refresh rate). Therefore, for example, when the refresh rate is 60 Hz and the polarity inversion frequency is 30 Hz, which is half the refresh rate, the power accompanying polarity inversion, that is, the power accompanying charging / discharging of the pixel electrode is halved.
　このように、本発明の一態様によれば、極性反転周波数をリフレッシュレートよりも低くすることによって、極性反転に伴う電力、すなわち画素電極の充放電に伴う電力を低減することができる。よって、表示装置における消費電力の低減を実現できる。この際、表示装置では、リフレッシュレートを下げたり、飛び越し走査を行ったりしていないので、表示品位を下げずに消費電力を低減することができる。 Thus, according to one embodiment of the present invention, by reducing the polarity inversion frequency below the refresh rate, it is possible to reduce the power accompanying polarity inversion, that is, the power accompanying charging / discharging of the pixel electrode. Therefore, power consumption in the display device can be reduced. At this time, since the display device does not lower the refresh rate or perform interlaced scanning, power consumption can be reduced without lowering the display quality.
　本発明の他の目的、特徴、および優れた点は、以下に示す記載によって十分分かるであろう。また、本発明の利点は、添付図面を参照した次の説明で明白になるであろう。 Other objects, features, and superior points of the present invention will be fully understood from the following description. The advantages of the present invention will become apparent from the following description with reference to the accompanying drawings.
　本発明の一態様によれば、表示装置における画素電極の極性反転周波数がリフレッシュレートよりも低くなるので、極性反転に伴う電力、すなわち画素電極の充放電に伴う電力を低減することができる。よって、表示装置における消費電力の低減を実現できる。この際、表示装置では、リフレッシュレートを下げたり、飛び越し走査を行ったりしていないので、表示品位を下げずに消費電力を低減することができる。 According to one embodiment of the present invention, since the polarity inversion frequency of the pixel electrode in the display device is lower than the refresh rate, the power accompanying polarity inversion, that is, the power accompanying charging / discharging of the pixel electrode can be reduced. Therefore, power consumption in the display device can be reduced. At this time, since the display device does not lower the refresh rate or perform interlaced scanning, power consumption can be reduced without lowering the display quality.
図中の（ａ）は、従来の表示パネルにおける画素配列を示す構造図であり、図中の（ｂ）は、本発明の一実施形態に係る表示パネルにおける画素配列を示す構造図である。(A) in the figure is a structural diagram showing a pixel array in a conventional display panel, and (b) in the figure is a structural diagram showing a pixel array in a display panel according to an embodiment of the present invention. 本発明の一実施形態に係る表示システムの構成の詳細を示すブロック図である。It is a block diagram which shows the detail of a structure of the display system which concerns on one Embodiment of this invention. 図中の（ａ）は、従来の表示パネルにおける画素配列を示す構造図であり、図中の（ｂ）は、本発明の一実施形態に係る表示パネルにおける画素配列を示す構造図である。(A) in the figure is a structural diagram showing a pixel array in a conventional display panel, and (b) in the figure is a structural diagram showing a pixel array in a display panel according to an embodiment of the present invention. 図中の（ａ）は、従来の表示パネルにおける画素配列を示す構造図であり、図中の（ｂ）は、本発明の一実施形態に係る表示パネルにおける画素配列を示す構造図である。(A) in the figure is a structural diagram showing a pixel array in a conventional display panel, and (b) in the figure is a structural diagram showing a pixel array in a display panel according to an embodiment of the present invention. ドレイン電流Ｉｄｄとゲートオン電圧Ｖｇｈとの関係を表すグラフを示す図である。It is a figure which shows the graph showing the relationship between drain current Idd and the gate-on voltage Vgh. 図中の（ａ）は、横電界方式の液晶表示装置の１画素の断面を示す図であり、図中の（ｂ）は、縦電界方式の液晶表示装置の１画素の断面を示す図である。(A) in the figure is a diagram showing a cross section of one pixel of a horizontal electric field type liquid crystal display device, and (b) in the figure is a diagram showing a cross section of one pixel of a vertical electric field type liquid crystal display device. is there.
　図面に基づいて、本発明の実施形態について詳細に説明する。なお、以下の説明において、同一の機能および作用を示す部材については、同一の符号を付し、説明を省略する。 Embodiments of the present invention will be described in detail based on the drawings. In the following description, members having the same function and action are denoted by the same reference numerals and description thereof is omitted.
　〔第１の実施形態〕
　（表示システム１の構成）
　本実施形態に係る表示システム１の構成について、図２を参照して説明する。図２は、本実施形態に係る表示システム１の構成の詳細を示すブロック図である。図２に示すように、表示システム１は、表示装置２およびコントロール部３を有している。本実施形態の表示システム１では、コントロール部３は表示装置２を介して映像を表示出力している。本実施形態では、表示装置２における極性反転周波数の制御を行っているが、上記の制御はコントロール部３によって行うこともできるし、表示装置２のタイミングコントロール部７によって行うこともできる。なお、コントロール部３では、映像以外にも静止画像または記号等の任意の情報を、表示装置２を介して表示出力してもよい。 [First Embodiment]
(Configuration of display system 1)
A configuration of the display system 1 according to the present embodiment will be described with reference to FIG. FIG. 2 is a block diagram showing details of the configuration of the display system 1 according to the present embodiment. As shown in FIG. 2, the display system 1 includes a display device 2 and a control unit 3. In the display system 1 of the present embodiment, the control unit 3 displays and outputs an image via the display device 2. In this embodiment, the polarity inversion frequency in the display device 2 is controlled. However, the above control can be performed by the control unit 3 or the timing control unit 7 of the display device 2. The control unit 3 may display and output arbitrary information such as still images or symbols in addition to the video via the display device 2.
　表示装置２は、表示パネル２ａ、走査線駆動回路４、信号線駆動回路５（駆動回路）、共通電極駆動回路６、および、タイミングコントロール部７を有している。表示パネル２ａは、マトリクス状に配置された複数の画素からなる画面を備えている。また、表示パネル２ａは、画面を線順次に選択して走査するためのＮ本（Ｎは任意の整数）の走査信号線Ｇ（ゲートライン）を備えている。さらに、表示パネル２ａは、選択されたラインに含まれる一行分の画素にデータ信号を供給するＭ本（Ｍは任意の整数）のデータ信号線Ｓ（ソースライン）を備えている。走査信号線Ｇとデータ信号線Ｓとは互いに交差している。 The display device 2 includes a display panel 2a, a scanning line driving circuit 4, a signal line driving circuit 5 (driving circuit), a common electrode driving circuit 6, and a timing control unit 7. The display panel 2a includes a screen made up of a plurality of pixels arranged in a matrix. Further, the display panel 2a includes N (N is an arbitrary integer) scanning signal lines G (gate lines) for selecting and scanning the screen in a line-sequential manner. Further, the display panel 2a includes M (M is an arbitrary integer) data signal lines S (source lines) that supply data signals to pixels for one row included in the selected line. The scanning signal line G and the data signal line S cross each other.
　図２に示すＧ（ｎ）はｎ本目（ｎは１以上Ｎ以下の整数）の走査信号線Ｇを表す。例えば、Ｇ（１）、Ｇ（２）、および、Ｇ（３）は、それぞれ１本目、２本目および３本目の走査信号線Ｇを表す。一方、Ｓ（ｍ）はｍ本目（ｍは１以上Ｍ以下の整数）のデータ信号線Ｓを表す。例えば、Ｓ（１）、Ｓ（２）、および、Ｓ（３）は、それぞれ１本目、２本目および３本目のデータ信号線Ｓを表す。 G (n) shown in FIG. 2 represents the n-th scanning signal line G (n is an integer from 1 to N). For example, G (1), G (2), and G (3) represent the first, second, and third scanning signal lines G, respectively. On the other hand, S (m) represents the m-th data signal line S (m is an integer from 1 to M). For example, S (1), S (2), and S (3) represent the first, second, and third data signal lines S, respectively.
　走査線駆動回路４は、例えば各走査信号線Ｇを画面の上から下に向かって順次走査する。その際、各走査信号線Ｇに対して、画素に備えられ画素電極に接続されるスイッチング素子（画素薄膜トランジスタ（ＴＦＴ））をオン状態にさせるための矩形波を出力する。これにより、画面内の１行分の画素を選択状態にする。 The scanning line driving circuit 4 sequentially scans each scanning signal line G from the top to the bottom of the screen, for example. At that time, for each scanning signal line G, a rectangular wave for turning on a switching element (pixel thin film transistor (TFT)) provided in the pixel and connected to the pixel electrode is output. Thereby, the pixels for one row in the screen are selected.
　信号線駆動回路５は、コントロール部３から入力された映像信号（矢印Ａ）から、選択された１行分の各画素に出力すべき電圧の値を算出し、その値の電圧（データ信号）を各データ信号線Ｓに出力する。結果、選択された走査信号線Ｇ上にある各画素の画素電極に対して、画像データを供給する。 The signal line drive circuit 5 calculates the value of the voltage to be output to each pixel for the selected row from the video signal (arrow A) input from the control unit 3, and the voltage of that value (data signal) Is output to each data signal line S. As a result, image data is supplied to the pixel electrode of each pixel on the selected scanning signal line G.
　表示装置２は、画面内の各画素に対して設けられる共通電極（不図示）を備えている。共通電極駆動回路６は、タイミングコントロール部７から入力される信号（矢印Ｂ）に基づき、共通電極を駆動するための所定の共通電圧を共通電極に出力する（矢印Ｃ）。 The display device 2 includes a common electrode (not shown) provided for each pixel in the screen. The common electrode drive circuit 6 outputs a predetermined common voltage for driving the common electrode to the common electrode based on the signal (arrow B) input from the timing control unit 7 (arrow C).
　タイミングコントロール部７は、コントロール部３から入力されたクロック信号、水平同期信号、および、垂直同期信号（矢印Ｄ）に基づき、各回路が同期して動作するための基準となる信号を各回路に対して出力する。具体的には、走査線駆動回路４には、クロック信号、水平同期信号、および、垂直同期信号に基づいて、ゲートスタートパルス信号ＧＳＰ、ゲートクロック信号ＧＣＫ、および、ゲートアウトプットイネーブル信号ＧＯＥを出力する（矢印Ｅ）。信号線駆動回路５には、クロック信号、水平同期信号、および、垂直同期信号に基づいて、ソーススタートパルス信号ＳＳＰ、ソースラッチストローブ信号ＳＬＳ、および、ソースクロック信号ＳＣＫを出力する（矢印Ｆ）。 Based on the clock signal, the horizontal synchronization signal, and the vertical synchronization signal (arrow D) input from the control unit 3, the timing control unit 7 provides each circuit with a signal that serves as a reference for each circuit to operate in synchronization. Output. Specifically, the gate start pulse signal GSP, the gate clock signal GCK, and the gate output enable signal GOE are output to the scanning line driving circuit 4 based on the clock signal, the horizontal synchronization signal, and the vertical synchronization signal. (Arrow E). A source start pulse signal SSP, a source latch strobe signal SLS, and a source clock signal SCK are output to the signal line driver circuit 5 based on the clock signal, the horizontal synchronization signal, and the vertical synchronization signal (arrow F).
　走査線駆動回路４は、タイミングコントロール部７から受け取ったゲートスタートパルス信号ＧＳＰを合図に表示パネル２ａの走査を開始し、走査信号線Ｇの選択状態をシフトさせていく信号であるゲートクロック信号ＧＣＫに従って各走査信号線Ｇに順次選択電圧を印加していく。信号線駆動回路５は、タイミングコントロール部７から受け取ったソーススタートパルス信号ＳＳＰを基に、入力された各画素の画像データをソースクロック信号ＳＣＫに従ってレジスタに蓄える。そして、信号線駆動回路５は、画像データを蓄えた後に、次のソースラッチストローブ信号ＳＬＳに従って表示パネル２ａの各データ信号線Ｓを通して画素電極に画像データを書き込む。画像データの書き込みには、例えば信号線駆動回路５が有するアナログアンプが用いられる。 The scanning line driving circuit 4 starts scanning the display panel 2a with the gate start pulse signal GSP received from the timing control section 7 as a cue, and shifts the selection state of the scanning signal line G, which is a gate clock signal GCK. The selection voltage is sequentially applied to each scanning signal line G. Based on the source start pulse signal SSP received from the timing control unit 7, the signal line drive circuit 5 stores the input image data of each pixel in a register according to the source clock signal SCK. Then, after storing the image data, the signal line driving circuit 5 writes the image data to the pixel electrode through each data signal line S of the display panel 2a in accordance with the next source latch strobe signal SLS. For example, an analog amplifier included in the signal line driving circuit 5 is used for writing the image data.
　なお、表示システム１内の各回路が動作するために必要な電圧は、例えば電源生成回路（不図示）から供給されるが、この電源生成回路はコントロール部３に含まれていてもよい。表示システム１内の各回路が動作するために必要な電圧の一例として、信号線駆動回路５には電源電圧Ｖｄｄが供給される。 Note that the voltage necessary for the operation of each circuit in the display system 1 is supplied from, for example, a power generation circuit (not shown), but this power generation circuit may be included in the control unit 3. As an example of a voltage necessary for each circuit in the display system 1 to operate, the power supply voltage Vdd is supplied to the signal line driving circuit 5.
　（極性反転周波数の制御）
　フリッカ防止のため、走査信号線Ｇの方向およびデータ信号線Ｓの方向の少なくとも一方に配列した画素電極ごとに電圧の極性を反転させることが望ましい。そこで、表示装置２においては、画素電極ごとに電圧の極性を反転させる極性反転駆動を行っている。この際、上述したように、本実施形態では、表示装置２における極性反転周波数の制御を、コントロール部３またはタイミングコントロール部７が行っている。具体的には、例えばコントロール部３が制御を行う場合は、コントロール部３からタイミングコントロール部７が有する極性反転周波数制御部８に、極性反転周波数の設定情報を含む制御信号（矢印Ｄ）が入力される。極性反転周波数の設定情報を含む制御信号とは、表示装置２における画素電極の極性反転周波数を所定の周波数とするように指示する指示信号である。 (Control of polarity reversal frequency)
In order to prevent flicker, it is desirable to invert the polarity of the voltage for each pixel electrode arranged in at least one of the direction of the scanning signal line G and the direction of the data signal line S. Therefore, the display device 2 performs polarity inversion driving for inverting the polarity of the voltage for each pixel electrode. At this time, as described above, in the present embodiment, the control unit 3 or the timing control unit 7 controls the polarity inversion frequency in the display device 2. Specifically, for example, when the control unit 3 performs control, a control signal (arrow D) including setting information of the polarity inversion frequency is input from the control unit 3 to the polarity inversion frequency control unit 8 included in the timing control unit 7. Is done. The control signal including the setting information of the polarity inversion frequency is an instruction signal that instructs the polarity inversion frequency of the pixel electrode in the display device 2 to be a predetermined frequency.
　極性反転周波数制御部８では、コントロール部３からの制御信号に基づき、極性反転周波数を上記の所定の周波数に設定する。具体的には、極性反転周波数制御部８は、コントロール部３からの制御信号に基づき、信号線駆動回路５から各データ信号線Ｓを通して画素電極に印加する電圧の極性を制御することによって、極性反転周波数を制御している。 The polarity reversal frequency control unit 8 sets the polarity reversal frequency to the predetermined frequency based on the control signal from the control unit 3. Specifically, the polarity inversion frequency control unit 8 controls the polarity of the voltage applied to the pixel electrode from the signal line drive circuit 5 through each data signal line S based on the control signal from the control unit 3, thereby The inversion frequency is controlled.
　一方、タイミングコントロール部７が制御を行う場合は、コントロール部３からタイミングコントロール部７に、極性反転周波数の設定情報（矢印Ｄ）が入力される。極性反転周波数の設定情報とは、表示装置２における画素電極の極性反転周波数に設定する所定の周波数の情報である。 On the other hand, when the timing control unit 7 performs control, the polarity inversion frequency setting information (arrow D) is input from the control unit 3 to the timing control unit 7. The polarity inversion frequency setting information is information on a predetermined frequency set to the polarity inversion frequency of the pixel electrode in the display device 2.
　タイミングコントロール部７では、コントロール部３からの設定情報に基づき、表示装置２における画素電極の極性反転周波数を所定の周波数にする処理を行う。具体的には、タイミングコントロール部７は、コントロール部３からの設定情報に基づき、表示装置２における画素電極の極性反転周波数を所定の周波数とするように指示する指示信号を極性反転周波数制御部８に入力する。そして、極性反転周波数制御部８は、入力された指示信号に基づき、信号線駆動回路５から各データ信号線Ｓを通して画素電極に印加する電圧の極性を制御することによって、極性反転周波数を上記の所定の周波数に設定している。 The timing control unit 7 performs processing for setting the polarity inversion frequency of the pixel electrode in the display device 2 to a predetermined frequency based on the setting information from the control unit 3. Specifically, the timing control unit 7 generates an instruction signal for instructing the polarity inversion frequency of the pixel electrode in the display device 2 to be a predetermined frequency based on the setting information from the control unit 3. To enter. Then, the polarity inversion frequency control unit 8 controls the polarity of the voltage applied from the signal line driving circuit 5 to the pixel electrode through each data signal line S based on the input instruction signal, thereby setting the polarity inversion frequency to the above-described value. A predetermined frequency is set.
　なお、上記の所定の周波数は任意に設定可能な周波数であるが、少なくとも表示装置２におけるリフレッシュレートよりも低い周波数である。ただし、本実施形態に係る表示システム１においては、表示装置２における画素電極の極性反転周波数を、リフレッシュレートよりも低い周波数に設定した後にリフレッシュレート以上の周波数に設定する等、画素電極の極性反転周波数を適宜切替えることができる。したがって、上記の所定の周波数は、必ずしもリフレッシュレートよりも低い周波数とは限らない。 Note that the predetermined frequency is a frequency that can be arbitrarily set, but is at least a frequency lower than the refresh rate in the display device 2. However, in the display system 1 according to the present embodiment, the polarity inversion of the pixel electrode in the display device 2 is performed, for example, the polarity inversion frequency of the pixel electrode is set to a frequency lower than the refresh rate and then set to a frequency higher than the refresh rate. The frequency can be switched as appropriate. Therefore, the predetermined frequency is not necessarily a frequency lower than the refresh rate.
　（ドット反転駆動時の極性反転制御）
　極性反転駆動には、ドット反転駆動、ソース反転駆動、および、Ｚ－ｉｎｖ反転駆動等がある。第１の実施形態では、表示装置２がドット反転駆動を行う場合を例に挙げて説明する。図１中の（ａ）は、従来の表示パネルにおける画素配列を示す構造図であり、図１中の（ｂ）は、表示パネル２ａにおける画素配列を示す構造図である。本図では、第ｍフレーム～第ｍ＋３フレームにおける各画素電極の電圧の極性を示している。各画素電極の電圧の極性は、図中の＋（プラス）および－（マイナス）によって示されている。なお、図の簡略化のため、４行×４列（副画素ＲＧＢ＝１画素）の画素配列しか示していないが、これに限定されるものではない。 (Polarity inversion control during dot inversion driving)
Examples of polarity inversion driving include dot inversion driving, source inversion driving, and Z-inv inversion driving. In the first embodiment, a case where the display device 2 performs dot inversion driving will be described as an example. 1A is a structural diagram showing a pixel array in a conventional display panel, and FIG. 1B is a structural diagram showing a pixel array in the display panel 2a. In this figure, the polarity of the voltage of each pixel electrode in the mth frame to the m + 3th frame is shown. The polarity of the voltage of each pixel electrode is indicated by + (plus) and-(minus) in the figure. For simplification of the figure, only a pixel array of 4 rows × 4 columns (subpixel RGB = 1 pixel) is shown, but the present invention is not limited to this.
　図１中の（ａ）に示すように、従来のドット反転駆動は、隣り合うデータ信号線Ｓごとに印加する電圧の極性を反転させると共に、データ信号線Ｓに印加するデータ信号の極性を、駆動される走査信号線Ｇごとに反転させることで画素電極に印加するデータ信号の極性も反転させる。具体的には、第ｍフレームにおいて、１番目の走査信号線Ｇの駆動時に、副画素Ｒに着目すると、各画素電極に印加する電圧の極性を、１番目をプラス（＋）とし、以下順番に反転させている。次に、２番目の走査信号線Ｇの駆動時に、副画素Ｒに着目すると、各画素電極に印加する電圧の極性を、１番目をマイナス（－）とし、以下順番に反転させている。そして、３番目以降の走査信号線Ｇの駆動時にも同様に繰り返すことにより、図１中の（ａ）に示すように、走査信号線Ｇの方向およびデータ信号線Ｓの方向に隣り合う副画素Ｒの画素電極同士の電圧の極性を異なるようにすることができる。この際、副画素Ｇおよび副画素Ｂについても同様に駆動するが、副画素ＲＧＢ内でも隣り合う副画素の画素電極同士の電圧の極性を異なるようにすることが好ましい。 As shown in FIG. 1A, the conventional dot inversion driving inverts the polarity of the voltage applied to each adjacent data signal line S and the polarity of the data signal applied to the data signal line S. By reversing each scanning signal line G to be driven, the polarity of the data signal applied to the pixel electrode is also reversed. Specifically, when the first scanning signal line G is driven in the m-th frame, paying attention to the sub-pixel R, the polarity of the voltage applied to each pixel electrode is set to the first plus (+), and the following order. Is inverted. Next, when the second scanning signal line G is driven, paying attention to the sub-pixel R, the polarity of the voltage applied to each pixel electrode is set to minus (−) in the first order, and is inverted in the following order. By repeating the same in driving the third and subsequent scanning signal lines G, the subpixels adjacent to each other in the direction of the scanning signal line G and the direction of the data signal line S are shown in FIG. The polarity of the voltage between the R pixel electrodes can be made different. At this time, the sub-pixel G and the sub-pixel B are driven in the same manner, but it is preferable that the polarities of the voltages of the pixel electrodes of the adjacent sub-pixels are also different in the sub-pixel RGB.
　続く第ｍ＋１フレームでは、第ｍフレームとは逆の電圧の極性を、走査信号線Ｇごとに各画素電極に印加する。具体的には、１番目の走査信号線Ｇの駆動時に、副画素Ｒに着目すると、各画素電極に印加する電圧の極性を、１番目をマイナス（－）とし、以下順番に反転させている。次に、２番目の走査信号線Ｇの駆動時に、副画素Ｒに着目すると、各画素電極に印加する電圧の極性を、１番目をプラス（＋）とし、以下順番に反転させている。そして、３番目以降の走査信号線Ｇの駆動時にも同様に繰り返す。以降の第ｍ＋２フレームおよび第ｍ＋３フレームでも同様に走査信号線Ｇごとに各画素電極に印加する電圧の極性を反転させる。したがって、従来のドット反転駆動では、フレームごとに各画素電極の電圧の極性を反転させている。すなわち、リフレッシュレートと同じ周波数で極性反転を行っている。 In the subsequent (m + 1) th frame, the polarity of the voltage opposite to that of the mth frame is applied to each pixel electrode for each scanning signal line G. Specifically, when paying attention to the sub-pixel R when driving the first scanning signal line G, the polarity of the voltage applied to each pixel electrode is set to minus (−), and the order is inverted in the following order. . Next, when the second scanning signal line G is driven, paying attention to the sub-pixel R, the polarity of the voltage applied to each pixel electrode is changed to the plus (+), and the order is inverted in the following order. The same is repeated when the third and subsequent scanning signal lines G are driven. Similarly, in the subsequent m + 2 frame and m + 3 frame, the polarity of the voltage applied to each pixel electrode is inverted for each scanning signal line G. Therefore, in the conventional dot inversion drive, the polarity of the voltage of each pixel electrode is inverted for each frame. That is, polarity inversion is performed at the same frequency as the refresh rate.
　これに対して本実施形態では、図１中の（ｂ）に示すように、従来のドット反転駆動と同様に、走査信号線Ｇごとに各データ信号線Ｓに印加するデータ信号の極性を反転させることで画素電極に印加するデータ信号の極性も反転させる。この際、本実施形態では、第ｍフレームから第ｍ＋１フレームに移り変わる際には、各画素電極に印加する電圧の極性を反転させないように、極性反転周波数制御部８が制御している。 On the other hand, in this embodiment, as shown in FIG. 1B, the polarity of the data signal applied to each data signal line S is inverted for each scanning signal line G as in the conventional dot inversion driving. As a result, the polarity of the data signal applied to the pixel electrode is also reversed. At this time, in the present embodiment, the polarity inversion frequency control unit 8 controls so that the polarity of the voltage applied to each pixel electrode is not inverted when the mth frame is changed to the (m + 1) th frame.
　具体的には、第ｍフレームにおいて、１番目の走査信号線Ｇの駆動時に、副画素Ｒに着目すると、各画素電極に印加する電圧の極性を、１番目をプラス（＋）とし、以下順番に反転させている。続く第ｍ＋１フレームでも、第ｍフレームと同様に、１番目の走査信号線Ｇの駆動時に、副画素Ｒに着目すると、各画素電極に印加する電圧の極性を、１番目をプラス（＋）とし、以下順番に反転させている。そして、次の第ｍ＋２フレームでは、第ｍフレームおよび第ｍ＋１とは逆の電圧の極性を、走査信号線Ｇごとに各画素電極に印加する。具体的には、１番目の走査信号線Ｇの駆動時に、副画素Ｒに着目すると、各画素電極に印加する電圧の極性を、１番目をマイナス（－）とし、以下順番に反転させている。続く第ｍ＋３フレームでも、第ｍ＋２フレームと同様に、１番目の走査信号線Ｇの駆動時に、副画素Ｒに着目すると、各画素電極に印加する電圧の極性を、１番目をマイナス（－）とし、以下順番に反転させている。 Specifically, when the first scanning signal line G is driven in the m-th frame, paying attention to the sub-pixel R, the polarity of the voltage applied to each pixel electrode is set to the first plus (+), and the following order. Is inverted. In the subsequent m + 1th frame, similarly to the mth frame, when the first scanning signal line G is driven, when attention is paid to the subpixel R, the polarity of the voltage applied to each pixel electrode is set to the plus (+). These are reversed in order. In the next (m + 2) th frame, the polarity of the voltage opposite to that of the (m + 1) th frame and the (m + 1) th frame is applied to each pixel electrode for each scanning signal line G. Specifically, when attention is paid to the sub-pixel R when the first scanning signal line G is driven, the polarity of the voltage applied to each pixel electrode is set to minus (−) in the first order, and is inverted in the following order. . In the subsequent m + 3 frame, similarly to the m + 2 frame, when attention is paid to the sub-pixel R when the first scanning signal line G is driven, the polarity of the voltage applied to each pixel electrode is set to minus (−). These are reversed in order.
　このように、第ｍフレームから第ｍ＋１フレームに移り変わる際には、各画素電極の電圧の極性を反転させず、第ｍ＋１フレームから第ｍ＋２フレームに移り変わる際に各画素電極の電圧の極性を反転させている。そして、第ｍ＋２フレームから第ｍ＋３フレームに移り変わる際には、各画素電極の電圧の極性を反転させておらず、以下同様に繰り返す。したがって、本実施形態では、複数フレーム（図１の場合は２フレーム）ごとに各画素電極の電圧の極性を反転させている。すなわち、リフレッシュレートよりも低い周波数で極性反転を行っている。例えば、リフレッシュレートが６０Ｈｚであり、極性反転周波数をリフレッシュレートの半分の３０Ｈｚとした場合、極性反転に伴う電力、すなわち画素電極の充放電に伴う電力が半減する。 As described above, the polarity of the voltage of each pixel electrode is not inverted when the transition from the mth frame to the m + 1th frame is performed, and the polarity of the voltage of each pixel electrode is inverted when the transition from the (m + 1) th frame to the m + 2th frame. ing. When the frame changes from the (m + 2) th frame to the (m + 3) th frame, the polarity of the voltage of each pixel electrode is not inverted, and the same is repeated thereafter. Therefore, in this embodiment, the polarity of the voltage of each pixel electrode is inverted every plural frames (two frames in the case of FIG. 1). That is, polarity inversion is performed at a frequency lower than the refresh rate. For example, when the refresh rate is 60 Hz and the polarity inversion frequency is 30 Hz, which is half the refresh rate, the power accompanying polarity inversion, that is, the power accompanying charging / discharging of the pixel electrode is halved.
　このように、極性反転周波数をリフレッシュレートよりも低くすることによって、極性反転に伴う電力、すなわち画素電極の充放電に伴う電力を低減することができる。よって、表示装置２における消費電力の低減を実現できる。この際、表示装置２では、リフレッシュレートを下げたり、飛び越し走査を行ったりしていないので、表示品位を下げずに消費電力を低減することができる。 Thus, by making the polarity inversion frequency lower than the refresh rate, it is possible to reduce the power accompanying polarity inversion, that is, the power accompanying charging / discharging of the pixel electrode. Therefore, power consumption in the display device 2 can be reduced. At this time, since the display device 2 does not lower the refresh rate or perform interlaced scanning, power consumption can be reduced without lowering the display quality.
　なお、以上では、２フレームごとに各画素電極の電圧の極性を反転させている例を挙げたが、３つ以上のフレームごとに各画素電極の電圧の極性を反転させてもよく、特に限定はない。したがって、極性反転周波数としては、リフレッシュレートよりも低い周波数であれば、任意の周波数に設定することができる。 In the above example, the polarity of the voltage of each pixel electrode is inverted every two frames. However, the polarity of the voltage of each pixel electrode may be inverted every three or more frames. There is no. Therefore, the polarity inversion frequency can be set to an arbitrary frequency as long as it is lower than the refresh rate.
　〔第２の実施形態〕
　（ソース反転駆動時の極性反転制御）
　第２の実施形態では、表示装置２がソース反転駆動を行う場合を例に挙げて説明する。図３中の（ａ）は、従来の表示パネルにおける画素配列を示す構造図であり、（ｂ）は、表示パネル２ａにおける画素配列を示す構造図である。本図では、第ｍフレーム～第ｍ＋３フレームにおける各画素電極の電圧の極性を示している。各画素電極の電圧の極性は、図中の＋（プラス）および－（マイナス）によって示されている。なお、図の簡略化のため、４行×４列（副画素ＲＧＢ＝１画素）の画素配列しか示していないが、これに限定されるものではない。 [Second Embodiment]
(Polarity inversion control during source inversion drive)
In the second embodiment, a case where the display device 2 performs source inversion driving will be described as an example. 3A is a structural diagram showing a pixel array in a conventional display panel, and FIG. 3B is a structural diagram showing a pixel array in the display panel 2a. In this figure, the polarity of the voltage of each pixel electrode in the mth frame to the m + 3th frame is shown. The polarity of the voltage of each pixel electrode is indicated by + (plus) and-(minus) in the figure. For simplification of the figure, only a pixel array of 4 rows × 4 columns (subpixel RGB = 1 pixel) is shown, but the present invention is not limited to this.
　図３中の（ａ）に示すように、従来のソース反転駆動は、フレーム周期を通して、各フレームにおいて同極性のデータ信号を各データ信号線Ｓに供給したものである。具体的には、第ｍフレームにおいて、副画素Ｒに着目すると、各走査信号線Ｇの駆動時に、各データ信号線Ｓに印加する電圧の極性を、１番目をプラス（＋）とし、以下順番に反転させている。これにより、図３中の（ａ）に示すように、データ信号線Ｓの方向に配列した画素電極の電圧を同極性にしたまま、走査信号線Ｇの方向に配列した画素電極ごとに電圧の極性を反転させることができる。この際、副画素Ｇおよび副画素Ｂについても同様に駆動するが、副画素ＲＧＢ内でも隣り合う副画素の画素電極同士の電圧の極性を異なるようにすることが好ましい。 As shown in (a) of FIG. 3, the conventional source inversion driving is one in which data signals having the same polarity are supplied to the data signal lines S in each frame through the frame period. Specifically, in the m-th frame, paying attention to the sub-pixel R, when driving each scanning signal line G, the polarity of the voltage applied to each data signal line S is the first plus (+), and the following order Is inverted. As a result, as shown in FIG. 3A, the voltage of each pixel electrode arranged in the direction of the scanning signal line G is maintained with the voltage of the pixel electrode arranged in the direction of the data signal line S having the same polarity. The polarity can be reversed. At this time, the sub-pixel G and the sub-pixel B are driven in the same manner, but it is preferable that the polarities of the voltages of the pixel electrodes of the adjacent sub-pixels are also different in the sub-pixel RGB.
　続く第ｍ＋１フレームでは、第ｍフレームとは逆の電圧の極性を、各データ信号線Ｓに印加する。具体的には、各走査信号線Ｇの駆動時に、副画素Ｒに着目すると、各データ信号線Ｓに印加する電圧の極性を、１番目をプラス（＋）とし、以下順番に反転させている。以降の第ｍ＋２フレームおよび第ｍ＋３フレームでも同様に各データ信号線Ｓに印加する電圧の極性を反転させる。したがって、従来のソース反転駆動では、フレームごとに各画素電極の電圧の極性を反転させている。すなわち、リフレッシュレートと同じ周波数で極性反転を行っている。 In the subsequent (m + 1) th frame, the polarity of the voltage opposite to that of the mth frame is applied to each data signal line S. Specifically, paying attention to the subpixel R when driving each scanning signal line G, the polarity of the voltage applied to each data signal line S is set to plus (+), and is inverted in the following order. . In the subsequent m + 2 frame and m + 3 frame, the polarity of the voltage applied to each data signal line S is similarly reversed. Therefore, in the conventional source inversion drive, the polarity of the voltage of each pixel electrode is inverted every frame. That is, polarity inversion is performed at the same frequency as the refresh rate.
　これに対して本実施形態では、図３中の（ｂ）に示すように、従来のソース反転駆動と同様に、フレーム周期を通して、各フレームにおいて同極性のデータ信号を各データ信号線Ｓに供給する。この際、本実施形態では、第ｍフレームから第ｍ＋１フレームに移り変わる際には、各データ信号線Ｓに印加する電圧の極性を反転させないように、極性反転周波数制御部８が制御している。具体的には、第ｍフレームにおいて、各走査信号線Ｇの駆動時に、副画素Ｒに着目すると、各データ信号線Ｓに印加する電圧の極性を、１番目をプラス（＋）とし、以下順番に反転させている。続く第ｍ＋１フレームでも、第ｍフレームと同様に、各走査信号線Ｇの駆動時に、副画素Ｒに着目すると、各データ信号線Ｓに印加する電圧の極性を、１番目をプラス（＋）とし、以下順番に反転させている。そして、次の第ｍ＋２フレームでは、第ｍフレームおよび第ｍ＋１とは逆の電圧の極性を、各データ信号線Ｓに印加する。具体的には、各走査信号線Ｇの駆動時に、副画素Ｒに着目すると、各データ信号線Ｓに印加する電圧の極性を、１番目をマイナス（－）とし、以下順番に反転させている。続く第ｍ＋３フレームでも、第ｍ＋２フレームと同様に、各走査信号線Ｇの駆動時に、副画素Ｒに着目すると、各データ信号線Ｓに印加する電圧の極性を、１番目をマイナス（－）とし、以下順番に反転させている。 On the other hand, in this embodiment, as shown in FIG. 3B, the data signal having the same polarity is supplied to each data signal line S in each frame through the frame period as in the conventional source inversion driving. To do. At this time, in this embodiment, the polarity inversion frequency control unit 8 controls so that the polarity of the voltage applied to each data signal line S is not inverted when the mth frame is changed to the (m + 1) th frame. Specifically, in driving the scanning signal lines G in the m-th frame, paying attention to the sub-pixel R, the polarity of the voltage applied to each data signal line S is set to the plus (+), and the following order. Is inverted. In the subsequent m + 1th frame, similarly to the mth frame, when the scanning signal line G is driven, when attention is paid to the subpixel R, the polarity of the voltage applied to each data signal line S is set to the plus (+). These are reversed in order. In the next (m + 2) th frame, the polarity of the voltage opposite to that of the (m + 1) th frame and the (m + 1) th frame is applied to each data signal line S. Specifically, when focusing on the sub-pixel R when driving each scanning signal line G, the polarity of the voltage applied to each data signal line S is negative (−), and is inverted in the following order. . In the subsequent m + 3 frame, similarly to the m + 2 frame, when focusing on the sub-pixel R when driving each scanning signal line G, the polarity of the voltage applied to each data signal line S is set to minus (−). These are reversed in order.
　このように、第ｍフレームから第ｍ＋１フレームに移り変わる際には、各画素電極の電圧の極性を反転させず、第ｍ＋１フレームから第ｍ＋２フレームに移り変わる際に各画素電極の電圧の極性を反転させている。そして、第ｍ＋２フレームから第ｍ＋３フレームに移り変わる際には、各画素電極の電圧の極性を反転させておらず、以下同様に繰り返す。したがって、本実施形態では、複数フレーム（図３の場合は２フレーム）ごとに各画素電極の電圧の極性を反転させている。すなわち、リフレッシュレートよりも低い周波数で極性反転を行っている。例えばリフレッシュレートが６０Ｈｚであり、極性反転周波数をリフレッシュレートの半分の３０Ｈｚとした場合、極性反転に伴う電力、すなわち画素電極の充放電に伴う電力が半減する。 As described above, the polarity of the voltage of each pixel electrode is not inverted when changing from the mth frame to the m + 1th frame, and the polarity of the voltage of each pixel electrode is inverted when changing from the m + 1th frame to the m + 2th frame. ing. When the frame changes from the (m + 2) th frame to the (m + 3) th frame, the polarity of the voltage of each pixel electrode is not inverted, and the same is repeated thereafter. Therefore, in this embodiment, the polarity of the voltage of each pixel electrode is inverted every plurality of frames (two frames in the case of FIG. 3). That is, polarity inversion is performed at a frequency lower than the refresh rate. For example, when the refresh rate is 60 Hz and the polarity inversion frequency is 30 Hz, which is half of the refresh rate, the power accompanying polarity inversion, that is, the power accompanying charging / discharging of the pixel electrode is halved.
　このように、極性反転周波数をリフレッシュレートよりも低くすることによって、極性反転に伴う電力、すなわち画素電極の充放電に伴う電力を低減することができる。よって、表示装置２における消費電力の低減を実現できる。さらに、本実施形態ではソース反転駆動を行っているため、各データ信号線Ｓにおける極性反転周波数も下げることができる。それ故、各データ信号線における極性反転に伴う電力、すなわち各データ信号線の充放電に伴う電力も低減することができるので、表示装置２における消費電力をより低減することができる。この際、表示装置２では、リフレッシュレートを下げたり、飛び越し走査を行ったりしていないので、表示品位を下げずに消費電力を低減することができる。 Thus, by making the polarity inversion frequency lower than the refresh rate, it is possible to reduce the power accompanying polarity inversion, that is, the power accompanying charging / discharging of the pixel electrode. Therefore, power consumption in the display device 2 can be reduced. Furthermore, since the source inversion drive is performed in this embodiment, the polarity inversion frequency in each data signal line S can also be lowered. Therefore, the power accompanying polarity inversion in each data signal line, that is, the power accompanying charging / discharging of each data signal line can also be reduced, so that the power consumption in the display device 2 can be further reduced. At this time, since the display device 2 does not lower the refresh rate or perform interlaced scanning, power consumption can be reduced without lowering the display quality.
　なお、以上では、２フレームごとに各画素電極の電圧の極性を反転させている例を挙げたが、極性反転周波数としては、リフレッシュレートよりも低い周波数であれば、任意の周波数に設定することができることは言うまでもない。また、図３では、隣り合うデータ信号線Ｓごとに印加する電圧の極性を反転させているが、必ずしもこれに限定されるわけではない。例えば、隣り合う複数のデータ信号線Ｓごとに印加する電圧の極性を反転させてもよく、特に限定はない。また、すべてのデータ信号線Ｓに同極性のデータ信号を印加し、その極性を複数のフレーム単位で反転させてもよい。 In the above example, the polarity of the voltage of each pixel electrode is inverted every two frames. However, the polarity inversion frequency may be set to any frequency as long as the frequency is lower than the refresh rate. Needless to say, you can. In FIG. 3, the polarity of the voltage applied to each adjacent data signal line S is inverted, but the present invention is not necessarily limited to this. For example, the polarity of the voltage applied to each of the plurality of adjacent data signal lines S may be reversed, and there is no particular limitation. Alternatively, a data signal having the same polarity may be applied to all the data signal lines S and the polarity may be inverted in units of a plurality of frames.
　〔第３の実施形態〕
　（Ｚ－ｉｎｖ反転駆動時の極性反転制御）
　第３の実施形態では、表示装置２がＺ－ｉｎｖ反転駆動を行う場合を例に挙げて説明する。図４中の（ａ）は、従来の表示パネルにおける画素配列を示す構造図であり、（ｂ）は、表示パネル２ａにおける画素配列を示す構造図である。本図では、第ｍフレーム～第ｍ＋３フレームにおける各画素電極の電圧の極性を示している。各画素電極の電圧の極性は、図中の＋（プラス）および－（マイナス）によって示されている。なお、図の簡略化のため、４行×４列（副画素ＲＧＢ＝１画素）の画素配列しか示していないが、これに限定されるものではない。 [Third Embodiment]
(Polarity reversal control during Z-inv reversal drive)
In the third embodiment, a case where the display device 2 performs Z-inv inversion driving will be described as an example. 4A is a structural diagram showing a pixel array in a conventional display panel, and FIG. 4B is a structural diagram showing a pixel array in the display panel 2a. In this figure, the polarity of the voltage of each pixel electrode in the mth frame to the m + 3th frame is shown. The polarity of the voltage of each pixel electrode is indicated by + (plus) and-(minus) in the figure. For simplification of the drawing, only a pixel array of 4 rows × 4 columns (subpixel RGB = 1 pixel) is shown, but the present invention is not limited to this.
　図４中の（ａ）に示すように、従来のＺ－ｉｎｖ反転駆動は、図３中の（ａ）と同じソース反転駆動であるが、図３中の（ａ）に比べて画素電極の配置が異なっている。図３中の（ａ）では、表示パネル２ａの任意の画素列における画素電極には、該画素電極に対して一方の側（図中の左側）に位置するデータ信号線Ｓから電圧が供給されている。これに対し、図４中の（ａ）では、表示パネル２ａの任意の画素列における奇数行の画素電極には、該画素電極に対して一方の側（図中の左側）に位置するデータ信号線Ｓから電圧が供給されており、上記の任意の画素列における偶数行の画素電極には、該画素電極に対して他方の側（図中の右側）に位置するデータ信号線Ｓから電圧が供給されている。換言すれば、任意の画素列における奇数行の画素電極と、上記の任意の画素列の隣の画素列における偶数行の画素電極とには、同一のデータ信号線Ｓから電圧が供給されている。このため、図３中の（ａ）の配置では、隣り合うデータ信号線Ｓの間に配置された画素電極の電圧の極性は同じである。しかし、図４中の（ａ）の配置では、隣り合うデータ信号線Ｓの間に配置された画素電極の電圧の極性は互い違いとなっている。したがって、本実施形態ではソース反転駆動を行っているが、画素電極の電圧の極性からみると、ドット反転駆動を行っているようにみえる。このようなＺ－ｉｎｖ反転駆動を行うことによって、表示品位を高めることができるという利点がある。 As shown in (a) of FIG. 4, the conventional Z-inv inversion drive is the same source inversion drive as (a) of FIG. 3, but the pixel electrode is compared with (a) of FIG. The arrangement is different. In FIG. 3A, a voltage is supplied to a pixel electrode in an arbitrary pixel column of the display panel 2a from a data signal line S positioned on one side (left side in the drawing) with respect to the pixel electrode. ing. On the other hand, in (a) of FIG. 4, the data signal located on one side (left side in the figure) of the pixel electrode of the odd-numbered row in the arbitrary pixel column of the display panel 2a with respect to the pixel electrode. A voltage is supplied from the line S, and the voltage is supplied from the data signal line S located on the other side (right side in the drawing) to the pixel electrode in the even-numbered row in the arbitrary pixel column. Have been supplied. In other words, the voltage is supplied from the same data signal line S to the pixel electrodes in the odd rows in the arbitrary pixel columns and the pixel electrodes in the even rows in the pixel columns adjacent to the arbitrary pixel columns. . For this reason, in the arrangement of FIG. 3A, the polarities of the voltages of the pixel electrodes arranged between the adjacent data signal lines S are the same. However, in the arrangement of FIG. 4A, the polarities of the voltages of the pixel electrodes arranged between the adjacent data signal lines S are staggered. Therefore, in this embodiment, source inversion driving is performed, but when viewed from the polarity of the voltage of the pixel electrode, it seems that dot inversion driving is performed. By performing such Z-inv inversion driving, there is an advantage that display quality can be improved.
　具体的には、第ｍフレームにおいて、副画素Ｒに着目すると、各走査信号線Ｇの駆動時に、各データ信号線Ｓに印加する電圧の極性を、１番目をプラス（＋）とし、以下順番に反転させている。これにより、図４中の（ａ）に示すように、データ信号線Ｓの方向に配列した画素電極の電圧を同極性にしたまま、走査信号線Ｇの方向に配列した画素電極ごとに電圧の極性を反転させることができる。この際、副画素Ｇおよび副画素Ｂについても同様に駆動するが、副画素ＲＧＢ内でも隣り合う副画素の画素電極同士の電圧の極性を異なるようにすることが好ましい。 Specifically, in the m-th frame, paying attention to the sub-pixel R, when driving each scanning signal line G, the polarity of the voltage applied to each data signal line S is the first plus (+), and the following order Is inverted. As a result, as shown in FIG. 4A, the voltage of each pixel electrode arranged in the direction of the scanning signal line G is maintained with the voltage of the pixel electrode arranged in the direction of the data signal line S having the same polarity. The polarity can be reversed. At this time, the sub-pixel G and the sub-pixel B are driven in the same manner, but it is preferable that the polarities of the voltages of the pixel electrodes of the adjacent sub-pixels are also different in the sub-pixel RGB.
　続く第ｍ＋１フレームでは、第ｍフレームとは逆の電圧の極性を、各データ信号線Ｓに印加する。具体的には、各走査信号線Ｇの駆動時に、副画素Ｒに着目すると、各データ信号線Ｓに印加する電圧の極性を、１番目をマイナス（－）とし、以下順番に反転させている。以降の第ｍ＋２フレームおよび第ｍ＋３フレームでも同様に各データ信号線Ｓに印加する電圧の極性を反転させる。したがって、従来のソース反転駆動では、フレームごとに各画素電極の電圧の極性を反転させている。すなわち、リフレッシュレートと同じ周波数で極性反転を行っている。 In the subsequent (m + 1) th frame, the polarity of the voltage opposite to that of the mth frame is applied to each data signal line S. Specifically, when focusing on the sub-pixel R when driving each scanning signal line G, the polarity of the voltage applied to each data signal line S is negative (−), and is inverted in the following order. . Similarly, in the subsequent m + 2 frame and m + 3 frame, the polarity of the voltage applied to each data signal line S is reversed. Therefore, in the conventional source inversion drive, the polarity of the voltage of each pixel electrode is inverted every frame. That is, polarity inversion is performed at the same frequency as the refresh rate.
　これに対して本実施形態では、図４中の（ｂ）に示すように、第ｍフレームから第ｍ＋１フレームに移り変わる際には、各データ信号線Ｓに印加する電圧の極性を反転させないように、極性反転周波数制御部８が制御している。具体的には、第ｍフレームにおいて、各走査信号線Ｇの駆動時に、副画素Ｒに着目すると、各データ信号線Ｓに印加する電圧の極性を、１番目をプラス（＋）とし、以下順番に反転させている。続く第ｍ＋１フレームでも、第ｍフレームと同様に、各走査信号線Ｇの駆動時に、副画素Ｒに着目すると、各データ信号線Ｓに印加する電圧の極性を、１番目をプラス（＋）とし、以下順番に反転させている。そして、次の第ｍ＋２フレームでは、第ｍフレームおよび第ｍ＋１とは逆の電圧の極性を、各データ信号線Ｓに印加する。具体的には、各走査信号線Ｇの駆動時に、副画素Ｒに着目すると、各データ信号線Ｓに印加する電圧の極性を、１番目をマイナス（－）とし、以下順番に反転させている。続く第ｍ＋３フレームでも、第ｍ＋２フレームと同様に、各走査信号線Ｇの駆動時に、副画素Ｒに着目すると、各データ信号線Ｓに印加する電圧の極性を、１番目をマイナス（－）とし、以下順番に反転させている。 On the other hand, in the present embodiment, as shown in FIG. 4B, the polarity of the voltage applied to each data signal line S is not reversed when changing from the mth frame to the (m + 1) th frame. The polarity reversal frequency control unit 8 controls. Specifically, in driving the scanning signal lines G in the m-th frame, paying attention to the sub-pixel R, the polarity of the voltage applied to each data signal line S is set to the plus (+), and the following order. Is inverted. In the subsequent m + 1th frame, similarly to the mth frame, when the scanning signal line G is driven, when attention is paid to the subpixel R, the polarity of the voltage applied to each data signal line S is set to the plus (+). These are reversed in order. In the next (m + 2) th frame, the polarity of the voltage opposite to that of the (m + 1) th frame and the (m + 1) th frame is applied to each data signal line S. Specifically, when focusing on the sub-pixel R when driving each scanning signal line G, the polarity of the voltage applied to each data signal line S is negative (−), and is inverted in the following order. . In the subsequent m + 3 frame, similarly to the m + 2 frame, when focusing on the sub-pixel R when driving each scanning signal line G, the polarity of the voltage applied to each data signal line S is set to minus (−). These are reversed in order.
　このように、第ｍフレームから第ｍ＋１フレームに移り変わる際には、各画素電極の電圧の極性を反転させず、第ｍ＋１フレームから第ｍ＋２フレームに移り変わる際に各画素電極の電圧の極性を反転させている。そして、第ｍ＋２フレームから第ｍ＋３フレームに移り変わる際には、各画素電極の電圧の極性を反転させておらず、以下同様に繰り返す。したがって、本実施形態では、複数フレーム（図４の場合は２フレーム）ごとに各画素電極の電圧の極性を反転させている。すなわち、リフレッシュレートよりも低い周波数で極性反転を行っている。例えばリフレッシュレートが６０Ｈｚであり、極性反転周波数をリフレッシュレートの半分の３０Ｈｚとした場合、極性反転に伴う電力、すなわち画素電極の充放電に伴う電力が半減する。 As described above, the polarity of the voltage of each pixel electrode is not inverted when changing from the mth frame to the m + 1th frame, and the polarity of the voltage of each pixel electrode is inverted when changing from the m + 1th frame to the m + 2th frame. ing. When the frame changes from the (m + 2) th frame to the (m + 3) th frame, the polarity of the voltage of each pixel electrode is not inverted, and the same is repeated thereafter. Therefore, in this embodiment, the polarity of the voltage of each pixel electrode is inverted every plural frames (two frames in the case of FIG. 4). That is, polarity inversion is performed at a frequency lower than the refresh rate. For example, when the refresh rate is 60 Hz and the polarity inversion frequency is 30 Hz, which is half of the refresh rate, the power accompanying polarity inversion, that is, the power accompanying charging / discharging of the pixel electrode is halved.
　このように、極性反転周波数をリフレッシュレートよりも低くすることによって、極性反転に伴う電力、すなわち画素電極の充放電に伴う電力を低減することができる。よって、表示装置２における消費電力の低減を実現できる。さらに、本実施形態ではソース反転駆動を行っているため、各データ信号線における極性反転周波数も下げることができる。それ故、各データ信号線における極性反転に伴う電力、すなわち各データ信号線の充放電に伴う電力も低減することができるので、表示装置２における消費電力をより低減することができる。この際、表示装置２では、リフレッシュレートを下げたり、飛び越し走査を行ったりしていないので、表示品位を下げずに消費電力を低減することができる。特に、Ｚ－ｉｎｖ反転駆動を行っているので、表示品位を高めることができる。 Thus, by making the polarity inversion frequency lower than the refresh rate, it is possible to reduce the power accompanying polarity inversion, that is, the power accompanying charging / discharging of the pixel electrode. Therefore, power consumption in the display device 2 can be reduced. Furthermore, since the source inversion drive is performed in this embodiment, the polarity inversion frequency in each data signal line can also be lowered. Therefore, the power accompanying polarity inversion in each data signal line, that is, the power accompanying charging / discharging of each data signal line can also be reduced, so that the power consumption in the display device 2 can be further reduced. At this time, since the display device 2 does not lower the refresh rate or perform interlaced scanning, power consumption can be reduced without lowering the display quality. In particular, since Z-inv inversion driving is performed, display quality can be improved.
　なお、以上では、２フレームごとに各画素電極の電圧の極性を反転させている例を挙げたが、極性反転周波数としては、リフレッシュレートよりも低い周波数であれば、任意の周波数に設定することができることは言うまでもない。 In the above example, the polarity of the voltage of each pixel electrode is inverted every two frames. However, the polarity inversion frequency may be set to any frequency as long as the frequency is lower than the refresh rate. Needless to say, you can.
　〔第４の実施形態〕
　（酸化物半導体の使用）
　各画素のＴＦＴの半導体層としては、アモルファスシリコンまたは低温ポリシリコン（ＬＴＰＳ；Low-Temperature Poly Silicon）等を用いることができるが、本実施形態では、ＴＦＴとして酸化物半導体を用いている。酸化物半導体とは、例えばＩＧＺＯ（ＩｎＧａＺｎＯｘ）等である。 [Fourth Embodiment]
(Use of oxide semiconductors)
As the semiconductor layer of the TFT of each pixel, amorphous silicon or low-temperature polysilicon (LTPS) can be used. In this embodiment, an oxide semiconductor is used as the TFT. The oxide semiconductor is, for example, IGZO (InGaZnOx).
　図５に、ドレイン電流Ｉｄｄとゲートオン電圧Ｖｇｈとの関係を表すグラフを示す。この図５では、酸化物半導体を用いたＴＦＴ、ａ－Ｓｉ（amorphous silicon）を用いたＴＦＴ、およびＬＴＰＳ（Low Temperature Poly Silicon）を用いたＴＦＴの各々の特性を示す。本図において、横軸（Ｖｇｈ）は、各ＴＦＴにおいてゲートに供給されるオン電圧の電圧値を示し、縦軸（Ｉｄ）は、各ＴＦＴにおけるソース－ドレイン間の電流量を示す。特に、図中において「ＴＦＴ－ｏｎ」と示されている期間は、オン電圧の電圧値に応じてオン状態となっている期間を示し、図中において「ＴＦＴ－ｏｆｆ」と示されている期間は、オン電圧の電圧値に応じてオフ状態となっている期間を示す。 FIG. 5 shows a graph showing the relationship between the drain current Idd and the gate-on voltage Vgh. FIG. 5 shows the characteristics of a TFT using an oxide semiconductor, a TFT using a-Si (amorphous silicon), and a TFT using LTPS (Low Temperature PolyPolysilicon). In this figure, the horizontal axis (Vgh) indicates the voltage value of the on-voltage supplied to the gate in each TFT, and the vertical axis (Id) indicates the amount of current between the source and drain in each TFT. In particular, a period indicated as “TFT-on” in the figure indicates a period in which the transistor is on according to the voltage value of the on-voltage, and a period indicated as “TFT-off” in the figure. Indicates a period in which it is in an OFF state according to the voltage value of the ON voltage.
　図５に示すように、図５に示すように、酸化物半導体を用いたＴＦＴでは、ａ－ＳｉおよびＬＴＰＳを用いたＴＦＴよりも、オフ状態の時の電流量（すなわち、電子移動度）が低い。このことから、酸化物半導体を用いたＴＦＴでは、ａ－ＳｉおよびＬＴＰＳを用いたＴＦＴよりも、ＴＦＴ－ｏｆｆ時のオフリークが著しく小さく、オフ特性が非常に優れていることが分かる。そのため、ＴＦＴとして酸化物半導体を用いれば、画素電極は電流を保持しやすいので、低周波駆動に適している。したがって、リフレッシュレートを３０Ｈｚ以下にまで下げやすくなるので、さらなる消費電力の低下が望める。 As shown in FIG. 5, in the TFT using an oxide semiconductor, as shown in FIG. 5, the amount of current (ie, electron mobility) in the off state is higher than that of a TFT using a-Si and LTPS. Low. From this, it can be seen that a TFT using an oxide semiconductor has significantly smaller off-leakage at the time of TFT-off and extremely excellent off characteristics than a TFT using a-Si and LTPS. For this reason, if an oxide semiconductor is used as the TFT, the pixel electrode is easy to hold current, which is suitable for low-frequency driving. Therefore, since the refresh rate can be easily lowered to 30 Hz or less, further reduction in power consumption can be expected.
　また、酸化物半導体を用いたＴＦＴは、ａ－Ｓｉを用いたＴＦＴよりも、オン状態の時の電流量（すなわち、電子移動度）が高い。図示は省略するが、酸化物半導体を用いたＴＦＴは、ａ－Ｓｉを用いたＴＦＴよりも、オン状態の時の電子移動度が２０～５０倍程度高く、オン特性が非常に優れていることが分かる。そのため、アモルファスシリコンと比較して、画素電極に電力を供給しやすく、オン特性がよい。それ故、ＴＦＴとして酸化物半導体を用いれば、リフレッシュレートを６０Ｈｚ以上にまで上げやすくなるので、消費電力を抑えつつ、高周波駆動を実現することができる。 In addition, a TFT using an oxide semiconductor has a higher amount of current (that is, electron mobility) in an on state than a TFT using a-Si. Although illustration is omitted, a TFT using an oxide semiconductor has an electron mobility about 20 to 50 times higher in an on state than a TFT using a-Si, and has excellent on characteristics. I understand. Therefore, compared to amorphous silicon, it is easier to supply power to the pixel electrode and the on-characteristic is better. Therefore, when an oxide semiconductor is used as the TFT, the refresh rate can be easily increased to 60 Hz or higher, and thus high frequency driving can be realized while suppressing power consumption.
　〔第５の実施形態〕
　（縦電界方式の液晶表示装置の使用）
　上述した表示パネル２ａは、液晶層を備える液晶パネルであってもよい。この場合、表示装置２は液晶表示装置となる。液晶表示装置の電界印加方式には、ＩＰＳ（In Plane Switching）方式等、横方向の電界を印加する横電界方式と、ＶＡ（Vertical Alignment）方式等、縦方向の電界を印加する縦電界方式がある。 [Fifth Embodiment]
(Use of vertical liquid crystal display device)
The display panel 2a described above may be a liquid crystal panel including a liquid crystal layer. In this case, the display device 2 is a liquid crystal display device. The electric field application method of the liquid crystal display device includes a horizontal electric field method that applies a horizontal electric field, such as an IPS (In Plane Switching) method, and a vertical electric field method that applies a vertical electric field, such as a VA (Vertical Alignment) method. is there.
　図６中の（ａ）に、横電界方式の液晶表示装置の１画素Ｘの断面図を示し、（ｂ）に、縦電界方式の液晶表示装置の１画素Ｙの断面図を示す。図６中の（ａ）に示すように、横電界方式の場合、液晶層を挟んで配設される１対の基板１３のうち、一方の内面側に画素電極９および共通電極１１を絶縁層１２で絶縁して設け、横方向の電界を印加している。横電界方式では、電気力線１０が疎な部分（電界強度が弱い部分）と、電気力線１０が密な部分（電界強度が強い部分）とがあり、液晶層における電界強度が一様ではない。そのため、交流駆動である極性反転周波数を下げると、液晶中の不純物が画素電極９に付着してイオン化し、分極を発せさせて焼き付き等を発生させる虞がある。したがって、横電界方式は、極性反転周波数を下げにくい構造である。 6A shows a cross-sectional view of one pixel X of a horizontal electric field type liquid crystal display device, and FIG. 6B shows a cross-sectional view of one pixel Y of a vertical electric field type liquid crystal display device. As shown in FIG. 6A, in the case of the lateral electric field method, the pixel electrode 9 and the common electrode 11 are provided on one inner surface side of the pair of substrates 13 disposed with the liquid crystal layer interposed therebetween as an insulating layer. 12 is provided with insulation, and a horizontal electric field is applied. In the horizontal electric field method, there are a portion where the electric lines of force 10 are sparse (a portion where the electric field strength is weak) and a portion where the electric lines of force 10 are dense (a portion where the electric field strength is strong), and the electric field strength in the liquid crystal layer is not uniform. Absent. For this reason, when the polarity inversion frequency, which is AC driving, is lowered, impurities in the liquid crystal may adhere to the pixel electrode 9 and ionize, causing polarization and causing burn-in or the like. Therefore, the transverse electric field method has a structure in which it is difficult to lower the polarity inversion frequency.
　これに対して縦電界方式では、図６中の（ｂ）に示すように、画素電極９を有する基板１３と、共通電極１１を有する基板１３との間に液晶層を挟んで、縦方向の電界を印加している。縦電界方式では、電気力線１０は均一に分布しており、液晶層における電界強度はほぼ一様である。そのため、液晶中の不純物が画素電極９に付着しにくい。つまり、縦電界方式は、極性反転周波数を上げやすい構造である。そこで、本実施形態に係る液晶表示装置は、縦電界方式であることが好ましい。 On the other hand, in the vertical electric field method, as shown in FIG. 6B, a liquid crystal layer is sandwiched between the substrate 13 having the pixel electrode 9 and the substrate 13 having the common electrode 11, and the vertical electric field method is used. An electric field is applied. In the vertical electric field method, the lines of electric force 10 are uniformly distributed, and the electric field strength in the liquid crystal layer is substantially uniform. Therefore, impurities in the liquid crystal are difficult to adhere to the pixel electrode 9. In other words, the vertical electric field method has a structure in which the polarity inversion frequency can be easily increased. Therefore, the liquid crystal display device according to this embodiment is preferably a vertical electric field type.
　したがって、本実施形態において縦電界方式の液晶表示装置を用いれば、極性反転周波数を上げたとしても、焼き付き等が発生する可能性が低い。よって、縦電界方式の液晶表示装置を用いれば、表示品位の低下を防ぎつつ、消費電力を低減することができる。 Therefore, if a vertical electric field type liquid crystal display device is used in this embodiment, even if the polarity inversion frequency is increased, there is a low possibility of occurrence of burn-in or the like. Therefore, when a vertical electric field liquid crystal display device is used, power consumption can be reduced while preventing deterioration in display quality.
　本発明は上述した実施形態ならびに変形例に限定されるものではなく、請求項に示した範囲で種々の変更が可能である。すなわち、異なる実施形態あるいは変形例にそれぞれ開示された技術的手段を適宜組み合わせて得られる実施形態についても、本発明の技術的範囲に含まれる。 The present invention is not limited to the above-described embodiments and modifications, and various modifications can be made within the scope indicated in the claims. In other words, embodiments obtained by appropriately combining technical means disclosed in different embodiments or modifications are also included in the technical scope of the present invention.
　〔実施形態の総括〕
　以上のように、本発明の一態様に係る表示装置は、上記の課題を解決するために、複数の走査信号線と、上記複数の走査信号線と交差する複数のデータ信号線と、上記複数の走査信号線および上記複数のデータ信号線の各交差点に形成された画素とを備えた表示パネルと、各上記データ信号線を通して各上記画素の画素電極にデータ信号を供給する駆動回路であって、複数のフレームごとに、各上記画素電極に供給する上記データ信号の極性を反転させる駆動回路とを備えていることを特徴としている。 [Summary of Embodiment]
As described above, a display device according to one embodiment of the present invention includes a plurality of scanning signal lines, a plurality of data signal lines intersecting with the plurality of scanning signal lines, and the plurality of the plurality of scanning signal lines. A driving panel for supplying a data signal to a pixel electrode of each pixel through each data signal line, and a display panel having a pixel formed at each intersection of the plurality of scanning signal lines and the plurality of data signal lines. And a drive circuit for inverting the polarity of the data signal supplied to each pixel electrode for each of a plurality of frames.
　また、本発明の一態様に係る表示装置の駆動方法は、上記の課題を解決するために、複数の走査信号線と、上記複数の走査信号線と交差する複数のデータ信号線と、上記複数の走査信号線および上記複数のデータ信号線の各交差点に形成された画素とを備えた表示パネルを有する表示装置の駆動方法であって、各上記データ信号線を通して各上記画素の画素電極にデータ信号を供給する駆動ステップであって、複数のフレームごとに、各上記画素電極に供給する上記データ信号の極性を反転させる駆動ステップを含んでいることを特徴としている。 In order to solve the above problems, a driving method of a display device according to one embodiment of the present invention includes a plurality of scanning signal lines, a plurality of data signal lines intersecting with the plurality of scanning signal lines, and the plurality of the plurality of scanning signal lines. A display device having a display panel having a scanning signal line and a pixel formed at each intersection of the plurality of data signal lines, wherein data is transferred to the pixel electrode of each pixel through each data signal line. A driving step of supplying a signal, the driving step including inverting the polarity of the data signal supplied to each of the pixel electrodes for each of a plurality of frames.
　従来のドット反転駆動では、フレームごとに各データ信号線を通して画素電極に供給するデータ信号の極性を反転させている。すなわち、リフレッシュレートと同じ周波数で極性反転を行っている。しかし、本発明の一態様によれば、複数のフレームごとに各画素電極に供給するデータ信号の極性を反転させている。すなわち、駆動回路が画素電極の極性を反転させる周波数（すなわち極性反転周波数）を、各走査信号線を選択して走査する周波数（すなわちリフレッシュレート）よりも低くしている。したがって、例えばリフレッシュレートが６０Ｈｚであり、極性反転周波数をリフレッシュレートの半分の３０Ｈｚとした場合、極性反転に伴う電力、すなわち画素電極の充放電に伴う電力が半減する。 In the conventional dot inversion drive, the polarity of the data signal supplied to the pixel electrode through each data signal line is inverted every frame. That is, polarity inversion is performed at the same frequency as the refresh rate. However, according to one aspect of the present invention, the polarity of the data signal supplied to each pixel electrode is inverted every plurality of frames. That is, the frequency at which the drive circuit inverts the polarity of the pixel electrode (that is, the polarity inversion frequency) is set lower than the frequency at which each scanning signal line is selected and scanned (that is, the refresh rate). Therefore, for example, when the refresh rate is 60 Hz and the polarity inversion frequency is 30 Hz, which is half the refresh rate, the power accompanying polarity inversion, that is, the power accompanying charging / discharging of the pixel electrode is halved.
　このように、本発明の一態様によれば、極性反転周波数をリフレッシュレートよりも低くすることによって、極性反転に伴う電力、すなわち画素電極の充放電に伴う電力を低減することができる。よって、表示装置における消費電力の低減を実現できる。この際、表示装置では、リフレッシュレートを下げたり、飛び越し走査を行ったりしていないので、表示品位を下げずに消費電力を低減することができる。 Thus, according to one embodiment of the present invention, by reducing the polarity inversion frequency below the refresh rate, it is possible to reduce the power accompanying polarity inversion, that is, the power accompanying charging / discharging of the pixel electrode. Therefore, power consumption in the display device can be reduced. At this time, since the display device does not lower the refresh rate or perform interlaced scanning, power consumption can be reduced without lowering the display quality.
　さらに、本発明の一態様に係る表示装置においては、上記駆動回路は、フレーム周期を通して、各フレームにおいて同極性の上記データ信号を各上記データ信号線に供給することことを特徴としている。 Furthermore, in the display device according to one embodiment of the present invention, the drive circuit supplies the data signal having the same polarity to each data signal line in each frame throughout the frame period.
　上記の構成によれば、所謂ソース反転駆動を行っているため、各データ信号線における極性反転周波数も下げることができる。それ故、各データ信号線における極性反転に伴う電力、すなわち各データ信号線の充放電に伴う電力も低減することができるので、表示装置における消費電力をより低減することができる。 According to the above configuration, since so-called source inversion driving is performed, the polarity inversion frequency in each data signal line can also be lowered. Therefore, the power accompanying polarity inversion in each data signal line, that is, the power accompanying charging / discharging of each data signal line can be reduced, so that the power consumption in the display device can be further reduced.
　さらに、本発明の一態様に係る表示装置においては、上記表示パネルの任意の画素列における奇数行の上記画素電極と、上記任意の画素列の隣の画素列における偶数行の上記画素電極とには、同一の上記データ信号線から上記データ信号が供給されていることを特徴としている。 Furthermore, in the display device according to one embodiment of the present invention, the odd-numbered pixel electrodes in an arbitrary pixel column of the display panel and the even-numbered pixel electrodes in a pixel column adjacent to the arbitrary pixel column are provided. Is characterized in that the data signal is supplied from the same data signal line.
　上記の構成によれば、所謂Ｚ－ｉｎｖ反転駆動を行っているため、表示品位を高めつつ、表示装置における消費電力をより低減することができる。 According to the above configuration, since so-called Z-inv inversion driving is performed, power consumption in the display device can be further reduced while improving display quality.
　さらに、本発明の一態様に係る表示装置においては、上記画素は、薄膜トランジスタを有しており、上記薄膜トランジスタの半導体層には、酸化物半導体が用いられていることを特徴としている。 Further, in the display device according to one embodiment of the present invention, the pixel includes a thin film transistor, and an oxide semiconductor is used for a semiconductor layer of the thin film transistor.
　さらに、本発明の一態様に係る液晶表示装置においては、上記酸化物半導体は、ＩＧＺＯであることが好ましい。 Furthermore, in the liquid crystal display device according to one embodiment of the present invention, the oxide semiconductor is preferably IGZO.
　酸化物半導体（例えば、ＩＧＺＯ）では、アモルファスシリコンおよび低温ポリシリコン（ＬＴＰＳ）と比較して、薄膜トランジスタ（ＴＦＴ）がオフの時のオフリークが著しく小さく、オフ特性がよい。それ故、ＴＦＴとして酸化物半導体を用いれば、画素電極は電流を保持しやすいので、低周波駆動に適している。したがって、リフレッシュレートを３０Ｈｚ以下にまで下げやすくなるので、さらなる消費電力の低下が望める。 An oxide semiconductor (eg, IGZO) has significantly lower off-leakage when the thin film transistor (TFT) is turned off and better off characteristics than amorphous silicon and low-temperature polysilicon (LTPS). Therefore, when an oxide semiconductor is used as the TFT, the pixel electrode is easy to hold current, which is suitable for low frequency driving. Therefore, since the refresh rate can be easily lowered to 30 Hz or less, further reduction in power consumption can be expected.
　また、酸化物半導体では、アモルファスシリコンと比較して、画素電極に電力を供給しやすく、オン特性がよい。それ故、ＴＦＴとして酸化物半導体を用いれば、リフレッシュレートを６０Ｈｚ以上にまで上げやすくなるので、消費電力を抑えつつ、高周波駆動を実現することができる。 In addition, an oxide semiconductor is easier to supply power to the pixel electrode than an amorphous silicon and has better on-characteristics. Therefore, when an oxide semiconductor is used as the TFT, the refresh rate can be easily increased to 60 Hz or higher, and thus high frequency driving can be realized while suppressing power consumption.
　なお、本発明の一態様に係る表示装置の例としては、液晶表示装置が挙げられる。 Note that examples of the display device according to one embodiment of the present invention include a liquid crystal display device.
　この際、液晶表示装置は、縦電界方式の液晶表示装置であることが好ましい。横電界方式では、電気力線が疎な部分（電界強度が弱い部分）と、電気力線が密な部分（電界強度が強い部分）とがあり、液晶層における電界強度が一様ではない。そのため、交流駆動である極性反転周波数を下げると、液晶中の不純物が画素電極に付着してイオン化し、分極を発せさせて焼き付き等を発生させる虞がある。これに対して縦電界方式では、電気力線は均一に分布しており、液晶層における電界強度はほぼ一様である。そのため、液晶中の不純物が画素電極に付着しにくい。したがって、縦電界方式の液晶表示装置を用いれば、極性反転周波数を上げたとしても、焼き付き等が発生する可能性が低い。よって、表示品位の低下を防ぎつつ、消費電力を低減することができる。 In this case, the liquid crystal display device is preferably a vertical electric field type liquid crystal display device. In the horizontal electric field method, there are a portion where the electric lines of force are sparse (a portion where the electric field strength is weak) and a portion where the electric lines of force are dense (a portion where the electric field strength is strong), and the electric field strength in the liquid crystal layer is not uniform. For this reason, when the polarity inversion frequency, which is AC driving, is lowered, impurities in the liquid crystal may adhere to the pixel electrode and be ionized to cause polarization and cause burn-in. On the other hand, in the vertical electric field method, the lines of electric force are uniformly distributed, and the electric field strength in the liquid crystal layer is almost uniform. For this reason, impurities in the liquid crystal are unlikely to adhere to the pixel electrode. Therefore, if a vertical electric field type liquid crystal display device is used, even if the polarity inversion frequency is increased, the possibility of image sticking or the like is low. Therefore, power consumption can be reduced while preventing deterioration in display quality.
　発明の詳細な説明の項においてなされた具体的な実施形態または実施例は、あくまでも、本発明の技術内容を明らかにするものであって、そのような具体例にのみ限定して狭義に解釈されるべきものではなく、本発明の精神と次に記載する請求の範囲内で、いろいろと変更して実施することができるものである。 The specific embodiments or examples made in the detailed description section of the invention are merely to clarify the technical contents of the present invention, and are limited to such specific examples and are interpreted in a narrow sense. It should be understood that various modifications may be made within the spirit of the invention and the scope of the following claims.
　以上のように、本発明に係る表示装置は、極性反転周波数をリフレッシュレートよりも下げることによって、表示装置の表示品位を下げずに消費電力の低減を実現しているので、極性反転駆動を行う任意の表示装置に適用することができる。 As described above, the display device according to the present invention achieves a reduction in power consumption without lowering the display quality of the display device by lowering the polarity inversion frequency below the refresh rate. It can be applied to any display device.
　１　　表示システム
　２　　表示装置
　２ａ　表示パネル
　３　　コントロール部
　４　　走査線駆動回路
　５　　信号線駆動回路
　６　　共通電極駆動回路
　７　　タイミングコントロール部
　９　　画素電極
　１０　電気力線
　１１　共通電極
　１２　絶縁層
　１３　基板 DESCRIPTION OF SYMBOLS 1 Display system 2 Display apparatus 2a Display panel 3 Control part 4 Scan line drive circuit 5 Signal line drive circuit 6 Common electrode drive circuit 7 Timing control part 9 Pixel electrode 10 Electric force line 11 Common electrode 12 Insulating layer 13 Substrate

Claims (7)

  1. 　複数の走査信号線と、上記複数の走査信号線と交差する複数のデータ信号線と、上記複数の走査信号線および上記複数のデータ信号線の各交差点に形成された画素とを備えた表示パネルと、
    　各上記データ信号線を通して各上記画素の画素電極にデータ信号を供給する駆動回路であって、複数のフレームごとに、各上記画素電極に供給する上記データ信号の極性を反転させる駆動回路とを備えていることを特徴とする表示装置。     A display panel comprising a plurality of scanning signal lines, a plurality of data signal lines intersecting with the plurality of scanning signal lines, and a pixel formed at each intersection of the plurality of scanning signal lines and the plurality of data signal lines When,
    A drive circuit for supplying a data signal to the pixel electrode of each pixel through each data signal line, the drive circuit for inverting the polarity of the data signal supplied to each pixel electrode for each of a plurality of frames; A display device.
  2. 　上記駆動回路は、フレーム周期を通して、各フレームにおいて同極性の上記データ信号を各上記データ信号線に供給することを特徴とする請求項１に記載の表示装置。 2. The display device according to claim 1, wherein the driving circuit supplies the data signal having the same polarity to each data signal line in each frame through a frame period.
  3. 　上記表示パネルの任意の画素列における奇数行の上記画素電極と、上記任意の画素列の隣の画素列における偶数行の上記画素電極とには、同一の上記データ信号線から上記データ信号が供給されていることを特徴とする請求項２に記載の表示装置。 The data signal is supplied from the same data signal line to the pixel electrodes in the odd rows in the arbitrary pixel columns of the display panel and the pixel electrodes in the even rows in the pixel columns adjacent to the arbitrary pixel columns. The display device according to claim 2, wherein the display device is a display device.
  4. 　上記画素は、薄膜トランジスタを有しており、
    　上記薄膜トランジスタの半導体層には、酸化物半導体が用いられていることを特徴とする請求項１～３のいずれか１項に記載の表示装置。     The pixel has a thin film transistor,
    The display device according to any one of claims 1 to 3, wherein an oxide semiconductor is used for the semiconductor layer of the thin film transistor.
  5. 　上記酸化物半導体は、ＩＧＺＯ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 oxide semiconductor is IGZO.
  6. 　上記表示装置は、縦電界方式の液晶表示装置であることを特徴とする請求項１～５のいずれか１項に記載の表示装置。 The display device according to any one of claims 1 to 5, wherein the display device is a vertical electric field type liquid crystal display device.
  7. 　複数の走査信号線と、上記複数の走査信号線と交差する複数のデータ信号線と、上記複数の走査信号線および上記複数のデータ信号線の各交差点に形成された画素とを備えた表示パネルを有する表示装置の駆動方法であって、
    　各上記データ信号線を通して各上記画素の画素電極にデータ信号を供給する駆動ステップであって、複数のフレームごとに、各上記画素電極に供給する上記データ信号の極性を反転させる駆動ステップを含んでいることを特徴とする駆動方法。     A display panel comprising a plurality of scanning signal lines, a plurality of data signal lines intersecting with the plurality of scanning signal lines, and a pixel formed at each intersection of the plurality of scanning signal lines and the plurality of data signal lines A method for driving a display device comprising:
    A driving step of supplying a data signal to the pixel electrode of each of the pixels through each of the data signal lines, the driving step including inverting the polarity of the data signal supplied to each of the pixel electrodes for each of a plurality of frames. A driving method characterized by comprising:
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Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPH0916132A (en) * 1995-06-28 1997-01-17 Casio Comput Co Ltd Liquid crystal driving device
WO2010106713A1 (en) * 2009-03-18 2010-09-23 シャープ株式会社 Liquid crystal display device and method for driving same
WO2011030819A1 (en) * 2009-09-10 2011-03-17 シャープ株式会社 Liquid crystal display device

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPH0916132A (en) * 1995-06-28 1997-01-17 Casio Comput Co Ltd Liquid crystal driving device
WO2010106713A1 (en) * 2009-03-18 2010-09-23 シャープ株式会社 Liquid crystal display device and method for driving same
WO2011030819A1 (en) * 2009-09-10 2011-03-17 シャープ株式会社 Liquid crystal display device

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