JP2008139610A - Liquid crystal display device and method of driving liquid crystal display device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a liquid crystal display device capable of suppressing a fluctuation of a common potential VCOM in an effective pixel driving period and suppressing defective picture quality due to the fluctuation of the common potential VCOM without thickening a line of VCOM line, giving a layout margin only to the VCOM line and forming a line within the pixel into a matrix structure. <P>SOLUTION: In a period (horizontal scanning period) where the precharging is not performed, the VCOM line 41 is electrically connected with a precharge line 44 by change-over switches ISW1 to ISWx of an impedance change-over circuit, low impedance of the whole VCOM line 41 including a VCOM electrode 23 and a CS line 24 is materialized and, thereby, the fluctuation of the common potential VCOM in the effective pixel driving period is suppressed. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a liquid crystal display device and a driving method of the liquid crystal display device, and more particularly to an active matrix type liquid crystal display device and a driving method thereof.

  The liquid crystal display device obtains contrast by applying a voltage to the liquid crystal cell. In the active matrix liquid crystal display device, the voltage is applied to the liquid crystal cell by providing a capacitor (auxiliary capacitor) and a switch element (pixel switch) in the pixel region, and charging the auxiliary capacitor via the pixel switch. Is done by.

  Incidentally, in the active matrix type liquid crystal display device, in recent years, there has been a problem that the impedance of the wiring in the liquid crystal panel becomes higher as the resolution of the display device becomes higher. Similarly, in a large liquid crystal panel corresponding to a large screen, the wiring length in the liquid crystal panel inevitably increases because the wiring length becomes relatively long as the liquid crystal panel increases in size.

  In a liquid crystal panel, a VCOM line is wired in common to all pixels as a counter electrode of a liquid crystal cell (so-called solid wiring), and not only serves to supply a common potential VCOM to the counter electrode, but also In order to perform the operation of supplying the common potential VCOM to the auxiliary capacitor Cs, the auxiliary capacitor Cs is also wired as a CS line in the pixel.

  For this reason, among the wirings in the liquid crystal panel, the length of the VCOM line is particularly long, which causes image quality defects. Since the common potential VCOM becomes a potential supplied to the pixel, the fluctuation of the common potential VCOM appears as a direct image, which affects the image quality. Therefore, it is required to reduce the impedance of the VCOM line.

  Here, as a typical image quality failure caused by the fluctuation of the common potential VCOM, there is an image quality failure called lateral crosstalk. For example, in horizontal scanning driving, the potential of the signal line during writing of the video signal to the signal line during phase development driving causes capacitive coupling with the common potential VCOM, thereby swinging the common potential VCOM. Since the holding voltage of the auxiliary capacitor Cs fluctuates due to the swing of the common potential VCOM, image quality defects such as lateral crosstalk occur.

  The fluctuation of the common potential VCOM increases as the impedance of the VCOM line increases. The same applies to image quality defects called window bands and tailing, and the fluctuations in the common potential VCOM caused by phase development during driving also appear as image quality defects.

  Here, the phase expansion drive means that n signal lines are wired to the pixel array portion in accordance with the number of pixels n in the horizontal direction, and then the number of video lines N (N << n) is less than n. Wiring on the panel, video signals are developed and input from the outside into N phases, and switch circuits are arranged in units of N between the N video lines and the n signal lines of the pixel array unit, By driving these switch circuits in units of N simultaneously using the same switch control signal, a driving method of simultaneously writing video signals developed in N phases for each pixel in the selected row in units of N pixels. Yes (see, for example, Patent Document 1).

JP 2003-323160 A

  In order to reduce the VCOM line impedance in order to suppress the image quality defect due to the fluctuation of the common potential VCOM, generally, the wiring of the VCOM line is made as thick as possible and laid out to every corner in the liquid crystal panel. ing. However, as the chip size of the liquid crystal panel is reduced and the resolution is increased, it is difficult to secure the layout area, and there is a limit to reducing the impedance of the VCOM line by making the wiring thicker. It is not possible to design with a margin for the layout.

  Further, since the VCOM line is used as an auxiliary capacitance electrode in the pixel, a method of reducing the wiring resistance by making the wiring in the pixel into a matrix structure is also one method for reducing the impedance of the VCOM line. However, when the wiring in the pixel has a matrix structure, the aperture ratio of the pixel is lowered and the transmittance characteristic is deteriorated. Further, although the impedance can be lowered by increasing the number of terminals of the VCOM line, there is a difficulty in reducing power consumption.

  Therefore, the present invention does not require a thick VCOM line, a design that allows only the VCOM line to have a layout, or a matrix structure of the wiring in the pixel. An object of the present invention is to provide a liquid crystal display device and a driving method thereof capable of suppressing the fluctuation of the common potential VCOM and suppressing the image quality defect caused by the fluctuation of the common potential VCOM.

  In order to achieve the above object, in the present invention, pixels including liquid crystal cells are two-dimensionally arranged in a matrix on a substrate, scanning lines are wired for each pixel row, and signal lines are wired for each pixel column. A pixel array unit; a first driving unit that selectively scans each pixel of the pixel array unit in a row unit via the scanning line; and a signal line connected to each pixel in a row selected by the first driving unit. And a second driving unit for writing a video signal through the second driving unit, a precharge signal is written to the signal line prior to the writing of the video signal to the signal line by the second driving unit. A pre-charge signal for supplying the precharge signal to a common line for supplying a common potential to all the pixels of the pixel array section to the counter electrode of the liquid crystal cell during a video signal writing period by the driving means of 2. It adopts a configuration for electrically connecting the over-di line.

  In the liquid crystal display device having the above-described configuration, the precharge line is electrically connected to the common line (VCOM line) during the video signal writing period by the second driving unit, so that only the wiring area of the precharge line is common. Since the wiring area of the entire line increases, the impedance of the common line can be reduced by the increase of the wiring area. In other words, the impedance of the common line can be reduced without making the wiring of the common line thick, designing the common line to have a sufficient layout, or making the wiring in the pixel have a matrix structure.

  According to the present invention, it is possible to reduce the impedance of the common line without making the wiring of the common line thick, designing the layout so that only the common line has a margin, or making the wiring in the pixel into a matrix structure. As a result, since the fluctuation of the common potential VCOM during the video signal writing period can be suppressed, the image quality defect caused by the fluctuation of the common potential VCOM can be suppressed.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

  FIG. 1 is a system configuration diagram showing a configuration example of an active matrix liquid crystal display device according to an embodiment of the present invention. Here, the liquid crystal display device has a panel structure in which two substrates (not shown), at least one of which is transparent, are arranged to face each other and liquid crystal is sealed between the two substrates.

  In FIG. 1, a pixel 10 includes a pixel transistor 11 made of, for example, a TFT (Thin Film Transistor), a liquid crystal cell 12 having a pixel electrode connected to the drain electrode of the pixel transistor 11, and a pixel electrode of the liquid crystal cell 12. And an auxiliary capacitor 13 to which one electrode is connected, and a large number of pixels are arranged in a matrix (matrix shape) on one substrate to form a pixel array section 20. Here, the liquid crystal cell 12 means a liquid crystal capacitance generated between a pixel electrode and a counter electrode formed opposite to the pixel electrode.

  In the pixel array section 20, scanning lines 21-1 to 21-m are wired for each pixel row with respect to a pixel array of m rows and n columns, and signal lines 22-1 to 22-n are wired for each pixel column. ing. In each of the pixels 10 arranged in a matrix, the gate electrode of the pixel transistor 11 is connected to the scanning lines 21-1 to 21-m, and the source electrode is connected to the signal lines 22-1 to 22-n. Yes.

  The counter electrode of the liquid crystal cell 12 is a so-called solid wiring VCOM electrode 23 formed of ITO (Indium Tin Oxide) or the like on the other substrate (counter substrate) in common for all pixels. A common potential VCOM described later is applied to the VCOM electrode 23. Further, a CS line 24 for supplying a common potential VCOM to the other electrode of the auxiliary capacitor 13 is wired in the pixel array unit 20 for each pixel row, for example.

  As a drive circuit for driving each pixel 10 of the pixel array unit 20, a level shift circuit 31, a vertical (V) driver 32, a horizontal (H) driver 33, a horizontal switch circuit 34, a precharge control circuit 35, a precharge circuit 36, and An impedance switching circuit 37 is provided on the same substrate (panel) 38 as the pixel array unit 20.

  A common line (hereinafter referred to as “VCOM line”) 41 is wired along the three outer sides of the substrate 38 on the outermost peripheral portion of the substrate 38. The VCOM line 41 is connected to the VCOM electrode 23 through a conductive material (contact part) 42 and directly connected to the CS line 24, and two VCOM terminals VCOM-L and VCOM-R from the outside of the substrate 38. Is supplied to the counter electrode of the liquid crystal cell 12 and the other electrode of the auxiliary capacitor 13.

  Here, since the VCOM electrode 23 and the CS line 24 are electrically connected to the VCOM line 41, they can be regarded as a part of the VCOM line 41. Each wiring impedance of the VCOM electrode 23 and the CS line 24 is also an element that determines the overall impedance of the VCOM line 41. In addition, the connection location of the VCOM line 41 and the VCOM electrode 23 by the conductive material 42 is not limited to one location shown in FIG.

  The level shift circuit 31 performs level shift (level conversion) on a signal input from the outside of the substrate 38 to a level signal necessary for driving the pixel 20. Examples of signals input to the level shift circuit 31 from the outside of the substrate 38 include a precharge control signal PCG, a vertical clock signal VCK, a vertical start signal VST, a horizontal clock signal HCK, a horizontal start signal HST, and the like.

  The vertical driver 32 is a first driving means, and is constituted by, for example, a shift register. When the vertical start signal VST is supplied from the level shift circuit 31, the vertical driver 32 is sequentially synchronized with the vertical clock signal VCK supplied from the level shift circuit 31. A pulse is transferred to the next transfer stage, and a scan pulse for selectively scanning each pixel 10 of the pixel array unit 20 in units of rows is output from each transfer stage. This scanning pulse is sequentially applied to each pixel 10 in units of rows via the scanning lines 21-1 to 21-m, thereby driving the pixel transistors 12 of each pixel 10 on / off in units of rows.

  The horizontal driver 33 is constituted by, for example, a shift register. When the horizontal start signal HST is supplied from the level shift circuit 31, the horizontal driver 33 sequentially pulses to the next transfer stage in synchronization with the horizontal clock signal HCK supplied from the level shift circuit 31. And a horizontal switch pulse for driving each horizontal switch of the horizontal switch circuit 34 is output at a predetermined timing from each transfer stage.

  This liquid crystal display device employs, for example, a phase expansion drive method as a drive method. Therefore, on the substrate (panel) 38, the number of n signal lines 22-1 to 22-n wired according to the number n of pixels in the horizontal direction of the pixel array unit 20 is smaller than n. For example, three video lines 43-1, 43-2, and 43-3 are wired. The video signals SIG1, SG2, and SIG3 developed in three phases are input to the three video lines 43-1, 43-2, and 43-3 from the outside of the substrate 38.

  The horizontal switch circuit 34 is configured by horizontal switches HSW1 to HSWn arranged between the three video lines 43-1, 43-2, 43-3 and the n signal lines 22-1 to 22-n. For example, three adjacent switches are used as a unit. For example, CMOS switches are used as the horizontal switches HSW1 to HSWn.

  The horizontal switch circuit 34 is vertically turned on / off by horizontal switch pulses sequentially output from the horizontal driver 33 in units of three switches (HSW1 to HSW3,..., HSWn-2 to HSWn). The video signals SIG1, SG2, and SIG3 developed in three phases are simultaneously written to each pixel 10 of the selected row by the driver 32 in units of three pixels. The horizontal driver 33 and the horizontal switch circuit 34 constitute second driving means.

  Here, in the liquid crystal display device, the common potential (signal center) VCOM is mainly used in order to prevent deterioration of the specific resistance (resistance value peculiar to the substance) of the liquid crystal due to the continuous application of the DC voltage of the same polarity to the liquid crystal. In addition, an AC driving method is employed in which the polarity of the video signal is inverted at a period of 1H (H is a horizontal period) or 1F (F is a field period). That is, the video signals SIG1, SG2, and SIG3 are analog video signals that have been converted to alternating current.

  Inside the VCOM line 41 on the substrate 38, precharge lines 44 are wired along, for example, three sides of the substrate 38. The precharge line 44 receives a precharge signal Psig input to two precharge terminals Psig_L and Psig_R from the outside of the substrate 38 on the side opposite to the horizontal driver 33 across the pixel array unit 20, on the flexible substrate side of the panel ( It is supplied to a precharge circuit 36 disposed on the opposite side to the pad side.

  The precharge terminals Psig_L and Psig_R have two inputs like the VCOM terminals VCOM-L and VCOM-R, and are in a state of being electrically connected within the substrate (panel) 38 by the precharge line 44. Thus, by adopting a two-input form for the precharge signal Psig, generally, the influence of the impedance of the precharge line 44 on the precharge signal Psig can be halved, so that the precharge capability can be enhanced.

  Note that the input form of the precharge signal Psig is not limited to a two-input form, and may be a one-input form or a three-input or more form.

  Based on the precharge control signal PCG given from the level shift circuit 31, the precharge control circuit 35 outputs a control signal for controlling the precharge circuit 36 and the impedance switching circuit 37 at a predetermined timing.

  The precharge circuit 36 includes n precharge switches PSW1 to PSWn corresponding to the number n of columns of the pixel array of the pixel array unit 20 between each of the signal lines 22-1 to 22-n and the precharge line 44. It is constituted by being connected to. For example, CMOS switches are used as the precharge switches PSW1 to PSWn.

  The precharge circuit 36 is generally output from the precharge control circuit 35 before the horizontal scanning drive prior to the video signal writing to the signal lines 22-1 to 22-n by the horizontal switch circuit 34. When the precharge switches PSW1 to PSWn are turned on in response to the reverse phase control signal, the precharge signal Psig supplied through the precharge line 44 is written to the signal lines 22-1 to 22-n (precharge).

  Here, when the precharge is not performed, that is, when the precharge signal Psig is not written in advance to the signal lines 22-1 to 22-n prior to the video signal writing, for example, when performing 1H inversion driving, When the charge / discharge current due to the writing of the video signal to the signal lines 22-1 to 22-n is large, noise such as vertical stripes appears on the display screen.

  In contrast, the precharge signal Psig is written in advance to the signal lines 22-1 to 22-n prior to the writing of the video signal. Generally, in the normally white type, the gray level or the black level is set to the precharge potential Psig. Since the charging / discharging current due to the subsequent video signal writing can be suppressed by writing as, noise such as vertical stripes can be reduced.

  FIG. 2 shows a general precharge driving timing in the case of 1H inversion driving. The precharge is performed during a blanking period after writing effective pixels. The precharge potential Psig is written to the signal lines 22-1 to 22-n at a timing when the pixel transistor 11 is turned off and the signal lines 22-1 to 22-n and the pixel electrodes of the liquid crystal cell 12 are not conductive.

  Specifically, the black potential (PSIG-Black) and the gray potential (PSIG-Grey) are written to the signal lines 22-1 to 22-n as the precharge potential Psig during the precharge period (PCG period). In general, the black potential is effective for crosstalk and the gray potential is effective for vertical stripes.

  The impedance switching circuit 37 includes a plurality of x changeover switches ISW1 to ISWx connected between the VCOM line 41 and the precharge line 44. Here, as the changeover switches ISW1 to ISWx, for example, a configuration using a CMOS switch is employed, but a switch configuration using a single channel transistor may be used.

  Each of the changeover switches ISW1 to ISWx is supplied with control signals having opposite phases to each other to drive the precharge switches PSW1 to PSWn output from the precharge control circuit 35, with the polarity being inverted by the inverters 45 and 46, respectively. .

  Thereby, the changeover switches ISW1 to ISWx are turned off when the precharge switches PSW1 to PSWn are turned on, and turned on when the precharge switches PSW1 to PSWn are turned off. Specifically, in the precharge period. It is turned off and turned on in the effective pixel writing period (horizontal scanning period).

  Here, a control signal having a polarity opposite to that of the control signal for driving the precharge switches PSW1 to PSWn output from the precharge control circuit 35 is generated, and the changeover switches ISW1 to ISWx are driven by the signal. It is also possible to adopt a configuration in which a control signal for turning on the changeover switches ISW1 to ISWx is input from the outside of the substrate 38 in the effective pixel writing period (horizontal scanning period).

  Here, since the precharge potential Psig inputted to the precharge line 44 from the two precharge terminals Psig_L and Psig_R is a potential used in the precharge period, it needs to be an intended potential in the precharge period. However, it is not necessary to have an intended potential in the effective pixel writing period, and the potential in the effective pixel writing period is not specified. Therefore, the precharge line 44 is in a state (so-called idle state) that does not affect other circuit operations during the effective pixel writing period.

  In view of this point, in the present invention, the VCOM line 41 and the precharge line 44 are electrically connected to each other during a period when the precharge is not performed (horizontal scanning period) as shown in FIG. And the potential of the precharge line 44 is set to the common potential VCOM. In other words, normal precharge is performed during the precharge period, and the horizontal scan period (effective pixel writing period) during which no precharge is performed does not use the precharge line 44 as a precharge drive. The potential of the precharge line 44 is set to the common potential VCOM.

  As described above, the VCOM line 41 and the precharge line 44 are electrically connected in the horizontal scanning period in which the video signal is written to each pixel 10 in the selected row of the pixel array unit 20, so that the VCOM line 41 to the precharge line 44 are connected. As a result, the entire wiring area of the VCOM line 41 including the VCOM electrode 23 and the CS line 24 is increased by the wiring area of the precharge line 44, and the VCOM line 41 is increased by the increase of the wiring area. The overall impedance can be reduced, and the driving capability of the wiring can be improved.

  As a result, the common potential VCOM is relatively strengthened, and fluctuations in the common potential VCOM can be suppressed. Therefore, it is difficult to secure the layout area of the VCOM line 41 by reducing the chip size and increasing the resolution of the liquid crystal panel. Even if the VCOM line 41 is thick, or the layout of the VCOM line 41 only has a margin, or the wiring in the pixel does not have a matrix structure, effective pixel driving is possible. Crosstalks called “lateral crosstalk” caused by fluctuations in the common potential VCOM of the image, ghosts of sample hold deviation when sampling video signals, and “window bands” caused by fluctuations in the common potential VCOM in the block Image quality defects can be suppressed.

  In addition, since the common potential VCOM is strengthened, drift of the common potential VCOM can also be suppressed. In the liquid crystal display device according to the present embodiment, the VCOM line 41 is provided with two inputs from the VCOM terminals VCOM-L and VCOM-R provided on the left and right sides of the substrate 38, and the precharge line 44 is also provided on the left and right sides of the substrate 38. The precharge terminals Psig_L and Psig_R have two inputs. Since the VCOM line 41 and the precharge line 44 are electrically connected by the changeover switches ISW1 to ISWx, the effect of strengthening the common potential VCOM is as follows. large.

  In particular, the image quality failure is caused by noise in the horizontal scanning period being superimposed on the common potential VCOM and appearing as image quality failure. Therefore, the VCOM line 41 and the precharge line 44 are electrically connected to each other within the horizontal scanning period. There is great significance in strengthening the common potential VCOM. Further, the precharge can be performed as usual, and there is no adverse effect caused by electrically connecting the VCOM line 41 and the precharge line 44.

  2 and 3 exemplify the case of 1H inversion driving, the configuration of the present invention is not limited to the liquid crystal display device of 1H inversion driving, but also to the liquid crystal display device of field inversion driving, and further to the common potential. The present invention can be applied to various types of driving in liquid crystal display devices such as VCOM-1H inversion driving and VCOM-1F inversion driving for inverting the polarity of VCOM at 1H period or 1F period, and the effect can be expected.

  In particular, the configuration of the present invention has a negative effect due to a recent increase in the resistance of the VCOM line 41 such as a narrow pitch panel due to the downsizing of the liquid crystal panel, an increase in the wiring resistance of the VCOM line 41 due to an increase in the size of the liquid crystal panel It becomes an effective means to solve the problem.

  In addition, when a driving method such as VCOM-1H inversion or VCOM-1F inversion is adopted, the voltage of the liquid crystal and the driving system for driving the liquid crystal can be lowered as well known. However, it is lower than when other driving methods are employed. As a result, slight fluctuations in the common potential VCOM have a greater adverse effect on image quality than when other driving methods are employed. From this point of view, it can be said that the effect of reducing the impedance of the VCOM line 41 and suppressing the fluctuation of the common potential VCOM is particularly great in the liquid crystal display device adopting the VCOM inversion driving method.

  In the above-described embodiment, the VCOM line 41 and the precharge line 44 are electrically connected by the plurality of changeover switches ISW1 to ISWx. However, the number of changeover switches ISW is not limited to a plurality and is one. There may be.

  However, if a plurality of changeover switches ISW are provided between the VCOM line 41 and the precharge line 44, more current paths can be formed even if the VCOM line 41 and the precharge line 44 are short-circuited. When this occurs, current can flow from the VCOM line 41 to the precharge line 44 through many current paths, which is advantageous in suppressing potential fluctuations in the VCOM line 41.

  In the above embodiment, the case where the present invention is applied to a liquid crystal display device adopting a three-phase expansion phase expansion driving method has been described as an example. However, the number of phase expansions is not limited to three, and phase expansion driving is also possible. The present invention is not limited to application to a liquid crystal display device employing the method.

  However, in the case of the phase expansion drive method, the number of pixels to be written at one time (number of phase expansions) increases due to restrictions on the writing period of the video signal, especially when the number of pixels increases with an increase in screen size and resolution. The video signal is written at a time with this number of pixels as a unit. Accordingly, the potential of the signal line fluctuates when the video signal is written to the signal line at the time of phase expansion driving, and the potential fluctuation of the signal line causes capacitive coupling with the common potential VCOM, thereby swinging the common potential VCOM.

  From such a viewpoint, the VCOM line 41 and the precharge line 44 are electrically connected in the horizontal scanning period in which the technique of the present invention, that is, the video signal is written to each pixel 10 in the selected row of the pixel array unit 20, and the VCOM line The technology for reducing the impedance of 41 can fully exert its effect by applying it to a phase expansion drive type liquid crystal display device in which the fluctuation of the common potential VCOM is likely to appear remarkably when a video signal is written. it can.

1 is a system configuration diagram illustrating a configuration example of an active matrix liquid crystal display device according to an embodiment of the present invention. FIG. 6 is a timing waveform diagram showing a general precharge drive timing. FIG. 6 is a timing waveform diagram showing precharge drive timing according to an embodiment of the present invention.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 10 ... Pixel, 11 ... Pixel transistor, 12 ... Liquid crystal cell, 13 ... Auxiliary capacity, 20 ... Pixel array part, 211-1 to 21-m ... Scan line, 22-1 to 22-n ... Signal line, 23 ... VCOM Electrode, 24 ... CS line, 31 ... Level shift circuit, 32 ... Vertical (V) driver, 33 ... Horizontal (H) driver, 34 ... Horizontal switch circuit, 35 ... Precharge control circuit, 36 ... Precharge circuit, 37 ... Impedance switching circuit, 38 ... board (panel), 41 ... VCOM line, 42 ... conductive material (contact part), 43-1, 43-2, 43-3 ... video line, 44 ... precharge line

Claims (5)

A pixel array unit in which pixels including liquid crystal cells are two-dimensionally arranged in a matrix on a substrate, a scanning line is wired for each pixel row, and a signal line is wired for each pixel column;
First driving means for selectively scanning each pixel of the pixel array section in units of rows via the scanning lines;
Second driving means for writing a video signal to each pixel in a row selected by the first driving means through the signal line;
Precharge means for writing a precharge signal to the signal line prior to video signal writing to the signal line by the second driving means;
A common line for supplying a common potential to all the pixels of the pixel array section to the counter electrode of the liquid crystal cell;
A precharge line for supplying the precharge signal to the precharge means;
A liquid crystal display device comprising: switch means for electrically connecting the precharge line to the common line during a video signal writing period by the second driving means. The liquid crystal display device according to claim 1, wherein the switch unit includes a plurality of switches connected between the common line and the precharge line. The second driving means phase-develops a video signal in N phases smaller than the number of the signal lines for each pixel in the row selected by the first driving means, and outputs N pixels. The liquid crystal display device according to claim 1, wherein writing is performed as a unit. The liquid crystal display device according to claim 1, wherein the polarity of the common potential is inverted in a period of one horizontal period or one field period. A pixel array unit in which pixels including liquid crystal cells are two-dimensionally arranged in a matrix on a substrate, a scanning line is wired for each pixel row, and a signal line is wired for each pixel column;
First driving means for selectively scanning each pixel of the pixel array section in units of rows via the scanning lines;
A driving method of a liquid crystal display device comprising: a second driving unit that writes a video signal through the signal line to each pixel in a row selected by the first driving unit,
Prior to writing a video signal to the signal line by the second driving means, a precharge signal is written to the signal line,
A precharge that supplies the precharge signal to a common line that supplies a common potential to all the pixels of the pixel array section to the counter electrode of the liquid crystal cell during a video signal writing period by the second driving means. A method for driving a liquid crystal display device, wherein the lines are electrically connected.

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