JP5540469B2 - Electro-optical device driving method, electro-optical device, and electronic apparatus - Google Patents

Description

  The present invention relates to a driving method for an electro-optical device such as a liquid crystal device, an electro-optical device, and an electronic apparatus.

  In this type of electro-optical device, the scanning lines and the data lines are wired on the substrate so as to intersect with each other, and a pixel portion including a pixel electrode is formed corresponding to the intersection, whereby a plurality of pixel portions are arranged in a matrix. Are arranged in a plane. Each pixel unit includes a pixel switching element made of, for example, a thin film transistor. When the electro-optical device is driven, when the pixel switching element is turned on by supplying a scanning signal from the scanning line driving circuit via the scanning line in each pixel unit, the pixel electrode is connected to the pixel electrode from the data line via the pixel switching element. Is supplied with an image signal.

  The driving method for driving such an electro-optical device has been devised to reduce display defects that occur during driving. For example, in Patent Document 1, a pixel area or a pixel array area (also referred to as an image display area) in which a plurality of pixel portions are arranged is divided into, for example, an upper and lower division or an upper and lower 4 for the purpose of reducing flicker on a display screen. Dividing into partial areas such as division, vertical scanning is performed for each of the areas, and the vertical scanning is performed alternately or alternately between the areas. Preferably, double speed driving is performed for each partial area and the double speed driving is performed. A scanning method (hereinafter simply referred to as “region scanning” or “region scanning method”) in which scanning is performed by skipping a linear array of pixel portions across regions, such as alternately or alternately between regions, is filed in this application. Proposed by people.

  On the other hand, in this type of electro-optical device, when the power is stopped (power is turned off), in order to prevent residual charges from remaining unevenly in a plurality of pixel parts, On the other hand, for example, after supplying an image signal related to black, the supply of the image signal to the data line is stopped (in other words, the data line is set to a high impedance state in which the data line is electrically disconnected). By performing such an off-sequence operation, residual charges that can remain unevenly in a plurality of pixel portions according to the image displayed in the pixel area immediately before the off-sequence operation after the power supply is stopped are practiced Therefore, it is possible to prevent the afterimage from being displayed in the pixel region (that is, so-called “burn-in”).

JP 2004-177930 A

  However, when the above-described off-sequence operation is performed while driving the electro-optical device by the area scanning described in Patent Document 1, the image signal supply to the data line is stopped in the off-sequence operation. At least for a certain period, the vertical scanning is continuously performed, and an indefinite potential may be written to the pixel portion from the data line in the high impedance state. As a result, there is a technical problem that residual charges may remain unevenly in a plurality of pixel portions.

  SUMMARY An advantage of some aspects of the invention is that it provides an electro-optical device driving method, an electro-optical device, and an electronic apparatus that can reduce a difference in residual charges in a plurality of pixel portions. Let it be an issue.

  In order to solve the above-described problem, a driving method of an electro-optical device according to the present invention supports a plurality of data lines and a plurality of scanning lines that extend so as to intersect each other, and an intersection of the plurality of data lines and the plurality of scanning lines. An electro-optical device driving method for driving an electro-optical device including a plurality of pixel portions arranged in a matrix by displaying the pixel portions in a pixel region in which the plurality of pixel portions are arranged. In the display period for displaying the power image, the vertical scanning in the vertical direction in which the data lines extend on the pixel region is basically based on the linear arrangement of the pixel portions arranged in the horizontal direction in which the scanning lines extend. A unit of m (where m is a natural number) or more is skipped in units of units, and an instruction to turn off the electro-optical device during the display period is input to the electro-optical device. In the off-sequence period started following the display period in accordance with the determined timing, at least the one-screen display period that is predetermined as a period during which one screen is displayed in the pixel area Vertical scanning is sequentially performed using the linear arrangement as a basic unit, and a potential signal having a predetermined potential is supplied to the data lines.

  According to the driving method of the electro-optical device according to the present invention, the electro-optical device such as a liquid crystal device is driven by the above-described area scanning method in the display period, for example. That is, in the electro-optical device driven by the driving method of the electro-optical device according to the present invention, vertical scanning in which, for example, area scanning is performed by skipping m or more line-shaped arrays in the display period. Is done. In this case, typically, horizontal scanning in one line array is involved. In horizontal scanning, writing may be performed simultaneously on a plurality of pixel units based on serial-parallel converted image signals.

  In the present invention, after writing a potential signal having a predetermined potential (for example, an image signal for displaying a black screen) to a plurality of pixel portions, an off-sequence period for setting a data line to a high impedance state in which the data line is electrically disconnected Is provided. The off-sequence period is started following the display period in accordance with the timing at which an instruction (for example, an off command) indicating that the electro-optical device should be turned off during the display period is input to the electro-optical device. . Further, the power source of the electro-optical device is turned off after the end of the off sequence period.

  Particularly in the present invention, in the off-sequence period, vertical scanning on the pixel region is performed sequentially for at least one screen display period (or also referred to as one vertical period) using a linear arrangement as a basic unit and a predetermined number of data lines are set. A potential signal having a potential is supplied. Here, “sequentially” means to perform one after another in the order of arrangement along the vertical direction of the linear array, for example, to skip the linear array from the upper side to the lower side in the pixel region. In other words, it means that one line arrangement is performed in order. In other words, in the off-sequence period, vertical scanning on the pixel region is performed and a potential signal having a predetermined potential is supplied to the data line so that adjacent scanning lines are selected in order for at least one screen display period. Therefore, a potential signal having a predetermined potential can be written to the plurality of pixel portions in at least one screen display period in the off-sequence period. Therefore, after the end of the off-sequence period (in other words, after the electro-optic device is turned off), it is possible to prevent the residual charges from remaining unevenly in the plurality of pixel portions (that is, The difference in residual charges in the plurality of pixel portions can be reduced). Thereby, it is possible to reduce or prevent the afterimage from being displayed in the pixel region of the electro-optical device.

  That is, according to the present invention, during the display period, for example, the display screen flicker can be reduced by driving the area scanning method described above, and an instruction to turn off the power is given to the electro-optical device. In accordance with the input timing, for example, driving in the above-described region scanning method is stopped, and in the off-sequence period, writing of a potential signal having a predetermined potential to a plurality of pixel portions is performed sequentially, and vertical scanning on the pixel region is sequentially performed. By doing so, it can be avoided that an indefinite potential is written to the pixel portion from the data line in the high impedance state, and as a result, the difference in residual charges in the plurality of pixel portions can be reduced. .

  As described above, according to the driving method of the electro-optical device according to the invention, it is possible to reduce the difference in residual charges in the plurality of pixel portions. Thereby, it is possible to reduce the afterimage from being displayed in the pixel region.

  In one aspect of the driving method of the electro-optical device according to the invention, in the display period, one horizontal scanning period that is predetermined as a period for performing horizontal scanning in the horizontal direction in the one linear array. Each time, an image signal to be supplied to the plurality of pixel portions is supplied to the data line while inverting the polarity with respect to a reference potential.

  According to this aspect, the electro-optical device can be driven by the above-described region scanning method while inverting the polarity for each line array in the display period. Therefore, the flicker on the display screen can be more reliably reduced. Therefore, a high quality image can be displayed.

  In order to solve the above-described problems, the electro-optical device of the present invention is driven by the above-described driving method (including various aspects thereof) of the electro-optical device according to the present invention.

  According to the electro-optical device of the present invention, since the electro-optical device is driven by the above-described driving method of the electro-optical device according to the present invention, it is possible to reduce the difference in residual charges in the plurality of pixel portions.

  In order to solve the above problems, an electronic apparatus according to the present invention includes the above-described electro-optical device according to the present invention (including various aspects thereof).

  According to the electronic apparatus of the present invention, since the above-described electro-optical device of the present invention is provided, a projection display device, a television set, a mobile phone, an electronic notebook, a word processor, and a viewfinder capable of performing high-quality image display. Various electronic devices such as a video tape recorder, a workstation, a videophone, a POS terminal, and a touch panel can be realized.

  The operation and other advantages of the present invention will become apparent from the best mode for carrying out the invention described below.

Hereinafter, embodiments of the present invention will be described with reference to the drawings. In the following embodiments, a liquid crystal device which is an example of an electro-optical device according to the invention is taken as an example.
<First Embodiment>
The liquid crystal device according to the first embodiment will be described with reference to FIGS.

  First, the overall configuration of the liquid crystal device according to the present embodiment will be described with reference to FIGS. 1 and 2.

  FIG. 1 is a plan view showing the configuration of the liquid crystal device according to the present embodiment, and FIG. 2 is a cross-sectional view taken along the line H-H ′ of FIG. 1.

  1 and 2, in the liquid crystal device according to the present embodiment, a TFT array substrate 10 and a counter substrate 20 are arranged to face each other. A liquid crystal layer 50 is sealed between the TFT array substrate 10 and the counter substrate 20, and the TFT array substrate 10 and the counter substrate 20 are surrounded by an image display region 10a as an example of the “pixel region” according to the present invention. They are bonded to each other by a sealing material 52 provided in a sealing region located in the area.

  In FIG. 1, a light-shielding frame light-shielding film 53 that defines the frame area of the image display region 10a is provided on the counter substrate 20 side in parallel with the inside of the seal region where the sealing material 52 is disposed. A data line driving circuit 101 and an external circuit connection terminal 102 are provided along one side of the TFT array substrate 10 in a region located outside the sealing region in which the sealing material 52 is disposed in the peripheral region. Further, the scanning line driving circuit 104 is provided so as to be covered with the frame light-shielding film 53 inside the seal region along two sides adjacent to the one side. On the TFT array substrate 10, vertical conduction terminals 106 for connecting the two substrates with the vertical conduction material 107 are arranged in regions facing the four corner portions of the counter substrate 20. Thus, electrical conduction can be established between the TFT array substrate 10 and the counter substrate 20.

  On the TFT array substrate 10, a lead wiring 90 is formed for electrically connecting the external circuit connection terminal 102 to the data line driving circuit 101, the scanning line driving circuit 104, the vertical conduction terminal 106, and the like. .

  In FIG. 2, on the TFT array substrate 10, there is formed a laminated structure in which pixel switching TFTs (Thin Film Transistors), which are driving elements, and wirings such as scanning lines and data lines are formed. In the image display area 10a, a pixel electrode 9a is provided in an upper layer of wiring such as a pixel switching TFT, a scanning line, and a data line. On the other hand, a light shielding film 23 is formed on the surface of the counter substrate 20 facing the TFT array substrate 10. A counter electrode 21 made of a transparent material such as ITO is formed on the light shielding film 23 so as to face the plurality of pixel electrodes 9a. A common potential LCCOM is supplied to the counter electrode 21 from an external power supply circuit (not shown) through the external circuit connection terminal 102, the routing wiring 90, the vertical conduction terminal 106, and the vertical conduction material 107.

  Further, the liquid crystal layer 50 is made of, for example, a liquid crystal in which one or several types of nematic liquid crystals are mixed, and takes a predetermined alignment state between the pair of alignment films.

  Although not shown here, in addition to the data line driving circuit 101 and the scanning line driving circuit 104, the TFT array substrate 10 is used for inspecting the quality, defects, and the like of the liquid crystal device during manufacturing or at the time of shipment. An inspection circuit, an inspection pattern, or the like may be formed.

  FIG. 3 is an equivalent circuit diagram of the pixel portion of the liquid crystal device according to the present embodiment.

  As shown in FIG. 3, in the image display area 10a, a plurality of scanning lines 11a and a plurality of data lines 6a are arranged so as to intersect each other, and each of the scanning lines 11a and the data lines 6a is interposed between the lines. A pixel portion to be selected is provided. In each pixel portion, a TFT 30, a pixel electrode 9a, and a storage capacitor 70 are provided. The TFT 30 is provided to apply the image signals S1, S2,..., Sn supplied from the data line 6a to the selected pixel, the gate is connected to the scanning line 11a, the source is connected to the data line 6a, and the drain is connected. It is connected to the pixel electrode 9a. The pixel electrode 9a forms a liquid crystal capacitance with the counter electrode 21, and applies the input image signals S1, S2,..., Sn to the pixel portion and holds them for a certain period. One electrode of the storage capacitor 70 is connected to the drain of the TFT 30 in parallel with the pixel electrode 9a, and the other electrode is connected to the capacitor wiring 400 with a fixed potential so as to have a constant potential.

  The liquid crystal device according to the present embodiment adopts a TFT active matrix driving method, and applies scanning signals G1, G2,..., G2m from the scanning line driving circuit 104 (see FIG. 1) to each scanning line 11a in the order described later. The image signals S1, S2,..., Sn from the data line driving circuit 101 (see FIG. 1) are applied to the horizontal selected pixel portion row where the TFT 30 is turned on through the data line 6a. It has become. At this time, the image signals S1, S2,..., Sn may be sequentially supplied to the data lines 6a, or may be supplied to the plurality of data lines 6a (for example, for each group) at the same timing. Also good. Thereby, an image signal is supplied to the pixel electrode 9a corresponding to the selected pixel portion. Since the TFT array substrate 10 is disposed so as to face the counter substrate 20 via the liquid crystal layer 50 (see FIG. 2), an electric field is applied to the liquid crystal layer 50 for each pixel section that is partitioned and arranged as described above. Thus, the amount of transmitted light between the two substrates is controlled for each pixel portion, and the image is displayed in gradation. In the normally white mode, the transmittance for incident light decreases according to the voltage applied in units of each pixel unit, and in the normally black mode, according to the voltage applied in units of each pixel. The transmittance for incident light is increased, and light having a contrast corresponding to an image signal is emitted from the liquid crystal device as a whole. In the following description, it is assumed that the liquid crystal device according to this embodiment is configured as a normally black mode.

  Further, the image signal held in each pixel unit at this time is prevented from leaking by the storage capacitor 70.

  In the following, for convenience of explanation, of the 2m scanning lines, the first scanning line 11a to which the scanning signal G1 is input is referred to as the scanning line G1 and the second scanning line to which the scanning signal G2 is input. The scanning line 11a is appropriately referred to as a scanning line G2, and the second m-th scanning line 11a to which the scanning signal G2m is input is appropriately referred to as a scanning line G2m.

  FIG. 4 is a block diagram including a drive unit of the liquid crystal device according to the present embodiment.

  As shown in FIG. 4, the driving unit 60 of the liquid crystal device according to the present embodiment includes a controller 61, a first frame memory 62, and a second frame memory 63 in addition to the data line driving circuit 101 and the scanning line driving circuit 104 described above. Frame memory for two screens, a DA converter 64, and the like. The controller 61 receives a vertical synchronization signal Vsync, a horizontal synchronization signal Hsync, a dot clock signal dotclk, and a source signal DATA. The controller 61 controls the operation timing of each component based on the vertical synchronization signal Vsync, the horizontal synchronization signal Hsync, and the dot clock signal dotclk, the write / read control of the first frame memory 62 and the second frame memory 63, and The source signal DATA corresponding to the scanning line 11a to be written is output from the frame memory to the DA converter 64. The first frame memory 62 and the second frame memory 63 alternately temporarily store the source signal DATA for one frame externally input to one side, for example, every frame, and the source signal DATA accumulated from the other side. Is used to output for display. The DA converter 64 performs DA (Digital to Analog) conversion on the source signal DATA read from the frame memory and outputs it to the data line drive circuit 101 as an image signal Sx. The data line driving circuit 101 applies the input image signal Sx to the corresponding data line 6a.

  The scanning line driving circuit 104 is configured to receive a clock signal CLY, an inverted clock signal CLY ′, a Y start pulse DY, and enable signals ENBY1 and ENBY2 from the controller 61. Further, the scanning line driving circuit 104 includes a shift register as will be described later. The Y start pulse DY input to the scanning line driving circuit 104 is shifted or transferred based on the clock signal CLY (and the inverted clock signal CLY ′) by each output stage of the shift register and sequentially output as an output signal. A logical product of the output signal and the enable signal ENBY1 or ENBY2 is output to the scanning line 11a as the scanning signals G1 to G2m.

  Next, the configuration of the scanning line driving circuit of the liquid crystal device according to the present embodiment will be described with reference to FIGS.

  FIG. 5 is a circuit diagram showing a circuit configuration of the scanning line driving circuit. FIG. 6 is a circuit diagram showing a circuit configuration of the shift register.

  5 and 6, the scan driving circuit 104 includes a shift register 66 and 2m AND circuits 67.

  As shown in FIG. 5, the shift register 66 receives a Y start pulse DY, a clock signal CLY, and an inverted clock signal CLY ′ from the controller 61 (see FIG. 4). As shown in FIG. 6, the shift register 66 includes a plurality of inverters 66a.

  In FIG. 5, each of 2m scanning lines 11 a is electrically connected to the output of each of 2m AND circuits 67. The 2m scanning lines 11a are divided into two blocks with the mth and m + 1th lines located in the center of the image display area 10a as the boundary, and each AND circuit 67 receives each output signal from the shift register 66 and two blocks. One of the enable signals ENBY1 and ENBY2 is input. That is, the output signal from the shift register 66 and the enable signal ENBY1 are input to the AND circuit 67 corresponding to the scanning lines G1 to Gm, and the output signal from the shift register 66 is input to the AND circuit 67 corresponding to the scanning lines Gm + 1 to G2m. The enable signal ENBY2 is input.

  Next, a driving method of the liquid crystal device according to the present embodiment will be described with reference to FIGS.

  FIG. 7 is a timing chart for explaining the driving method of the liquid crystal device according to the present embodiment. In FIG. 7, the Y start pulse DY in the display period ST1 and the off sequence period ST2 is shown together with the vertical synchronization signal Vsync. The display period ST1 is a period for displaying an image. The off sequence period ST2 is started following the display period ST1 by inputting an off command indicating that the power supply of the liquid crystal device should be turned off at the timing T1 in the display period ST1. The off sequence period ST2 includes a predetermined potential writing period STa for writing a predetermined potential signal having a predetermined potential to all the pixel portions, and a high impedance period STb in which the data line 6a is electrically disconnected and is in a high impedance state. Consists of. In the liquid crystal device according to the present embodiment, when an off command is input during the display period ST1, the predetermined potential writing period STa is started according to the input timing T1. Then, the power supply of the liquid crystal device is turned off after a high impedance period STb following the predetermined potential writing period STa.

  As shown in FIG. 7, in the display period ST1 and the predetermined potential writing period STa, the controller 61 is in one vertical period (that is, the period of the vertical synchronization signal Vsync) that is an example of the “one-screen display period” according to the present invention. Two Y start pulses DY are output to the scanning line driving circuit 104. As will be described in detail later, in the display period ST1, the controller 61 outputs two Y start pulses DY1 and DY2 to the scanning line driving circuit 104 for each vertical period as the Y start pulse DY, and displays the display period ST1. In the subsequent predetermined potential writing period STa, two Y start pulses DY1 ′ and DY2 ′ are output to the scanning line driving circuit 104 as the Y start pulse DY every vertical period. In the predetermined potential writing period STa, in order to prevent the residual charges from remaining unevenly in the pixel portions arranged in a matrix in the image display region 10a, a predetermined potential (this embodiment) is applied to the pixel electrodes 9a of all the pixel portions. Is a period for supplying a predetermined potential signal having a common potential LCCOM), and is provided as a part of the off-sequence period ST2 following the display period ST1.

  Here, a driving method of the liquid crystal device according to the present embodiment in the display period will be described with reference to FIGS.

  FIG. 8 is a timing chart for explaining the driving method of the liquid crystal device according to this embodiment in the display period. FIG. 9 is an explanatory diagram showing an image of the screen. FIG. 10 is an explanatory diagram for explaining the movement of the screen.

  FIG. 8 shows the Y start pulse DY, the clock signal CLY, the inverted clock signal CLY ′, the enable signals ENBY1 and ENBY2, the scanning signal Gi, and the image signal Sx in the display period ST1.

  In FIG. 8, the Y start pulse DY has four horizontal periods (that is, a period four times longer than one horizontal period (1H) predetermined as a period for performing horizontal scanning of a pixel column corresponding to one scanning line). ) And the shift register 66 of the scanning line driving circuit 104 is shifted by the clock signal CLY (and the inverted clock signal CLY ′) in which one pulse rises every two horizontal periods. Here, the Y start pulses DY1 and DY2 constituting the Y start pulse DY in the display period ST1 are input from the controller 61 with a shift of ½ vertical period, and in the shift register 66 with a shift of ½ vertical period. Shift each one. Further, when the Y start pulse DY reaches an area (specifically, the (m + 1) th scanning line) controlled by a different enable signal at the center of the screen, the phases of the enable signal ENBY1 and the enable signal ENBY2 are reversed. Through the above operation, the scanning signals G1,..., G2m are alternately output to two locations on the screen separated by m lines of the scanning lines 11a. That is, after jumping to the scanning line 11a that is m lines away from the predetermined scanning line 11a, the scanning line 11a is returned to the next scanning line 11a of the predetermined scanning line 11a and jumped to the scanning line 11a that is m lines away from the scanning line 11a. Are sequentially output so as to return to the next scanning line 11a (that is, in the order of scanning line G1, scanning line Gm + 1, scanning line G2, scanning line Gm + 2, scanning line G3,...).

  On the other hand, the polarity of the image signal Sx, which is an output from the data line driving circuit 101, is inverted to a positive potential and a negative potential every horizontal period with the common potential LCCOM as the center. Therefore, while the polarity of the image signal Sx is inverted every horizontal period, the scanning signals G1,..., Gm are alternately output to two portions of the screen separated by m lines of the scanning lines 11a in the above order. It will be.

  As a result, as shown in FIG. 9, when attention is paid to a certain horizontal period, for example, the pixel portion scanned by the scanning lines G3 to Gm + 2 becomes a region in which positive potential data is written, and the scanning lines G1 to G2 and Gm + 3 The pixel portion scanned in .about.G2m is in a state where the screen is divided into a positive polarity region and a negative polarity region, such as a region in which negative potential data is written.

  In FIG. 10, for example, in the first horizontal period, the 2m-th scanning line 11a is scanned by the scanning signal G2m, and the image signal Sx having a negative potential is written. In the second horizontal period, the (m + 1) th scanning line 11a is scanned by the scanning signal Gm + 1, and the image signal Sx having a positive potential is written to the pixel portion which has been a negative potential in the first horizontal period. In the third horizontal period, the first scanning line 11a is scanned by the scanning signal G1, and the image signal Sx having a negative potential is written to the pixel portion that was a positive potential in the first and second horizontal periods. Thereafter, such a selective writing operation is repeated. When half of the screen has been scanned, the positive polarity region and the negative polarity region are completely reversed, and one screen has been rewritten. According to this method, rewriting for one screen is performed twice in one vertical period.

  As described above, the liquid crystal device according to the present embodiment performs “region scanning” driving in the display period ST1.

  Next, a driving method of the liquid crystal device according to the present embodiment in the off sequence period will be described with reference to FIGS. 11 and 12 in addition to FIG.

  11 and 12 are timing charts for explaining a method of driving the liquid crystal device according to the present embodiment during the off-sequence period.

  7 and 11, a predetermined potential writing period STa is started following the display period ST1 by inputting an off command indicating that the power supply of the liquid crystal device should be turned off at timing T1 in the display period ST1. The The predetermined potential writing period STa is set as a period having the same length as one vertical period.

  In the predetermined potential writing period STa, the Y start pulse DY has a pulse width half that of the Y start pulse DY in the display period ST1 (that is, the controller 61 sets the Y start pulse DY so as to have a pulse width of two horizontal periods). Pulse width is changed). Further, in the predetermined potential writing period STa, the clock signal CLY has a half period of the clock signal CLY in the display period ST1 (that is, the period of the clock signal CLY is set by the controller 61 so that one pulse rises every horizontal period. Will be changed). In addition, in the predetermined potential writing period STa, the enable signals ENBY1 and ENBY2 are pulse signals that rise in response to the rise and fall of the clock signal CLY and have a narrower pulse width than the clock signal CLY.

  The Y start pulse DY is shifted in the shift register 66 of the scanning line driving circuit 104 by the clock signal CLY (and the inverted clock signal CLY ′) in which one pulse rises every horizontal period. Here, the Y start pulses DY1 and DY2 constituting the Y start pulse DY in the predetermined potential writing period STa are input from the controller 61 with a shift of ½ vertical period (that is, ½ period of one vertical period). Is done. The Y start pulses DY1 and DY2 are shifted in the shift register 66 alternately with a shift of ½ vertical period (in other words, the vertical scanning period in the predetermined potential writing period STa). That is, when the shift of the Y start pulse DY1 ′ in the shift register 66 is completed, the Y start pulse DY2 ′ is input to the shift register 66, and when the shift of the Y start pulse DY2 ′ in the shift register 66 is completed, A start pulse DY1 ′ is input. The output signal from the shift register 66 is ANDed with the enable signal ENBY1 or ENBY2. Through the above operation, the scanning signal is sequentially applied to the 2m scanning lines 11a from the upper side to the lower side of the screen (that is, in the order of the scanning line G1, the scanning line G2, the scanning line G3,..., The scanning line G2m). ) Is output. In other words, the adjacent scanning lines 11a are scanned (that is, selected from the first scanning line 11a to the 2m-th scanning line 11a in order without being skipped). ).

  On the other hand, a predetermined potential signal Vc having the same potential as the common potential LCCOM is output from the data line driving circuit 101 to the data line 6a as the image signal Sx.

  Therefore, in the predetermined potential writing period STa, the writing or rewriting of the predetermined potential signal Vc for one screen is performed twice (in one vertical period).

  As described above, the liquid crystal device according to the present embodiment performs “simple double speed driving” in which the scanning lines are sequentially scanned in the ½ vertical period in the predetermined potential writing period STa. Here, in the predetermined potential writing period STa, the predetermined potential signal Vc having the same potential as the common electrode LCCOM included in the counter electrode 21 (see FIG. 2) is supplied to all the pixel electrodes 9a. Thus, no voltage is applied to the liquid crystal layer 50 (see FIG. 2). Therefore, a black image is displayed in the entire image display area 10a of the liquid crystal device according to the present embodiment configured in the normally black mode.

  7 and 12, after the end of the predetermined potential writing period STa, a high impedance period STb in which the data line 6a is electrically disconnected is set to a high impedance state (Hi-Z). The high impedance period STb ends when the power supply of the liquid crystal device is stopped.

  In FIG. 12, in the high impedance period STb, the Y start pulse DY is not input to the scanning line driving circuit 104 (that is, the output of the Y start pulse DY to the scanning line driving circuit 104 by the controller 61 is stopped). Accordingly, the scanning signal is not output from the scanning line driving circuit 104. Accordingly, since the TFT 30 in the pixel portion can be maintained in the off state, it is possible to avoid an indefinite potential being written to the pixel portion from the data line 6a in the high impedance state.

  As described above, in the off-sequence period ST2, the predetermined potential signal Vc can be written to all the pixel portions in the predetermined potential writing period STa and the pixels from the data line 6a set in the high impedance state in the high impedance period STb. It can be avoided that an indefinite potential is written to the part. Therefore, after the end of the off-sequence period ST2 (in other words, after the power supply of the liquid crystal device is turned off), it is possible to prevent the residual charges from remaining unevenly in the plurality of pixel portions (that is, The difference in residual charges in the plurality of pixel portions can be reduced). Thereby, it is possible to reduce the afterimage from being displayed in the image display area 10a of the liquid crystal device according to the present embodiment.

  FIG. 13 is a timing chart having the same concept as in FIG. 12 in the comparative example. Although not shown here, the liquid crystal device according to the comparative example performs the “region scanning method” drive in the display period ST1 similarly to the liquid crystal device according to the present embodiment described above.

  In FIG. 13, according to the driving method of the liquid crystal device according to the comparative example, in the predetermined potential writing period STa subsequent to the display period ST1, the above-described “region driving method” is performed to drive the predetermined potential signal Vc to all the pixels. Write to the part. That is, in the predetermined potential writing period STa, as in the display period ST1, the Y start pulses DY1 and DY2 as the Y start pulse DY are shifted by ½ vertical period in one vertical period and are transferred to the shift register 66 of the scanning line driving circuit 104. The shift register 66 is shifted while being input and shifted by a ½ vertical period, and the output signal from the shift register 66 is ANDed with the enable signal ENBY1 or ENBY2 as a scanning signal. The signals are alternately output to two places on the screen of the m scanning lines 11a separated. On the other hand, a predetermined potential signal Vc having the same potential as the common potential LCCOM is output from the data line driving circuit 101 to the data line 6a as the image signal Sx.

  After the end of the predetermined potential writing period STa, a high impedance period STb in which the data line 6a is electrically disconnected is set to a high impedance state (Hi-Z). The high impedance period STb ends when the power supply of the liquid crystal device is stopped.

  Here, according to the driving method of the liquid crystal device according to the comparative example shown in FIG. 13, the scanning signal is output to the (m + 1) th to 2mth scanning lines 11a in the high impedance period STb, and the (m + 1) th to 2mth scanning lines are output. An indefinite potential is written from the data line 6a in the high impedance state to the pixel portion electrically connected to each of the scanning lines 11a.

  That is, the Y start pulse DY2 input from the controller 61 to the shift register 66 only 1/2 vertical period before the end of the predetermined potential write period STa is shifted by the shift register 66 at the end of the predetermined potential write period STa. Is not completed, and after the predetermined potential writing period STa is completed (that is, after the start of the high impedance period STb), the scanning signal Gm + 1, Gm + 2,. It will be output to the line 11a. Therefore, the TFT 30 of the pixel portion electrically connected to each of the (m + 1) -th to 2m-th scanning lines 11a is turned on, and the data line 6a and the pixel electrode 9a that are in a high impedance state in the pixel portion Are electrically connected. For this reason, an indefinite potential is written from the data line 6a in the high impedance state to the pixel electrode 9a of the pixel portion. As a result, residual charges may remain unevenly in a plurality of pixel portions.

However, according to the driving method of the liquid crystal device according to the present embodiment, as described above, in the predetermined potential writing period STa, “simple double speed driving” is performed in which all the scanning lines 11a are sequentially scanned in the ½ vertical period. Therefore, it is possible to avoid writing an indefinite potential from the data line 6a in the high impedance state to the pixel portion. Therefore, the difference in the residual charges in the plurality of pixel portions can be reduced or eliminated in practice.
<Electronic equipment>
Next, the case where the liquid crystal device which is the above-described electro-optical device is applied to various electronic devices will be described. First, a projector using this liquid crystal device as a light valve will be described. FIG. 14 is a plan view showing a configuration example of the projector. As shown in FIG. 14, a lamp unit 1102 including a white light source such as a halogen lamp is provided inside the projector 1100. The projection light emitted from the lamp unit 1102 is separated into three primary colors of RGB by four mirrors 1106 and two dichroic mirrors 1108 arranged in the light guide 1104, and serves as a light valve corresponding to each primary color. The light enters the liquid crystal panels 1110R, 1110B, and 1110G.

  The configurations of the liquid crystal panels 1110R, 1110B, and 1110G are the same as those of the liquid crystal device described above, and are driven by R, G, and B primary color signals supplied from the image signal processing circuit. The light modulated by these liquid crystal panels enters the dichroic prism 1112 from three directions. In the dichroic prism 1112, R and B light is refracted at 90 degrees, while G light travels straight. Therefore, as a result of the synthesis of the images of the respective colors, a color image is projected onto the screen or the like via the projection lens 1114.

  Here, paying attention to the display images by the liquid crystal panels 1110R, 1110B, and 1110G, the display image by the liquid crystal panel 1110G needs to be horizontally reversed with respect to the display images by the liquid crystal panels 1110R and 1110B.

  In addition, since light corresponding to each primary color of R, G, and B is incident on the liquid crystal panels 1110R, 1110B, and 1110G by the dichroic mirror 1108, it is not necessary to provide a color filter.

  In addition to the electronic device described with reference to FIG. 14, a mobile personal computer, a mobile phone, a liquid crystal television, a viewfinder type, a monitor direct view type video tape recorder, a car navigation device, a pager, and an electronic notebook , Calculators, word processors, workstations, videophones, POS terminals, devices with touch panels, and the like. Needless to say, the present invention can be applied to these various electronic devices.

  In addition to the liquid crystal device described in the above embodiment, the present invention also includes a reflective liquid crystal device (LCOS) in which elements are formed on a silicon substrate, a plasma display (PDP), a field emission display (FED, SED), The present invention can also be applied to an organic EL display, a digital micromirror device (DMD), an electrophoresis apparatus, and the like.

  The present invention is not limited to the above-described embodiments, and can be appropriately changed without departing from the spirit or idea of the invention that can be read from the claims and the entire specification, and an electro-optical device with such a change. The driving method, the electro-optical device, and the electronic apparatus including the electro-optical device are also included in the technical scope of the present invention.

It is a top view which shows the structure of the liquid crystal device which concerns on 1st Embodiment. It is the H-H 'sectional view taken on the line of FIG. 2 is an equivalent circuit diagram of a pixel portion of the liquid crystal device according to the first embodiment. FIG. It is a block diagram including the drive part of the liquid crystal device which concerns on 1st Embodiment. It is a circuit diagram which shows the circuit structure of a scanning line drive circuit. It is a circuit diagram which shows the circuit structure of a shift register. 3 is a timing chart for explaining a driving method of the liquid crystal device according to the first embodiment. 6 is a timing chart for explaining a driving method of the liquid crystal device according to the first embodiment in a display period. It is explanatory drawing which shows the image of a screen. It is explanatory drawing for demonstrating the motion of a screen. 6 is a timing chart (No. 1) for explaining a driving method of the liquid crystal device according to the first embodiment in the off-sequence period. 6 is a timing chart (No. 2) for explaining the driving method of the liquid crystal device according to the first embodiment in the off-sequence period. 6 is a timing chart for explaining a method of driving a liquid crystal device according to a comparative example. It is a top view which shows the structure of the projector which is an example of the electronic device to which the electro-optical apparatus is applied.

Explanation of symbols

  6a ... data line, 9a ... pixel electrode, 10 ... TFT array substrate, 10a ... image display area, 11a ... scanning line, 20 ... counter substrate, 21 ... counter electrode, 50 ... liquid crystal layer, 101 ... data line drive circuit, 102 ... External circuit connection terminal, 104 ... Scanning line driving circuit, ST1 ... Display period, ST2 ... Off sequence period, STa ... Predetermined potential writing period, STb ... High impedance period

Claims (4)

A plurality of data lines and a plurality of scanning lines intersecting each other; a plurality of pixels provided corresponding to the intersection of the plurality of data lines and the plurality of scanning lines; and an image display area including the plurality of pixels. Prepared,
The image display area includes m scanning lines (m is a natural number of 2 or more) among the plurality of scanning lines, and a positive polarity to which a positive polarity image signal is applied to a reference potential. An electro-optical device including a region and a negative region that includes m scanning lines of the plurality of scanning lines and to which a negative image signal is applied with respect to the reference potential,
A scanning line driving circuit for supplying a scanning signal in a predetermined order to the scanning line of the positive polarity region and the scanning line of the negative polarity region;
Data for supplying the positive polarity image signal or the negative polarity image signal corresponding to the scanning line supplied with the scanning signal to the data line in the display period and supplying a predetermined potential in the off-sequence period. Line drive circuit,
The scanning line driving circuit includes:
In the display period, the first start pulse and a second start pulse 1/2 that Do different vertical period phase one vertical period, the shift based on the first clock signal, based on said first start pulse Output a first scanning signal, and output a second scanning signal based on the second start pulse ,
In the off-sequence period, 1 a third start pulse and the fourth start pulse vertical period that Do different 1/2 vertical period phase, as well as shifts based on the second clock signal, the third start pulse A third scanning signal is output based on the fourth start signal, and a fourth scanning signal is output based on the fourth start pulse .
The pulse widths of the third start pulse and the fourth start pulse are half of the first start pulse and the second start pulse ,
2. The electro-optical device according to claim 1, wherein a period of the second clock signal is half that of the first clock signal.   In the display period, the image signal to be supplied to the corresponding image display area is inverted in polarity with respect to the reference potential for each horizontal scanning period, which is a period for selecting one scanning line. The electro-optical device according to claim 1, wherein the electro-optical device is supplied to a data line. A plurality of data lines and a plurality of scanning lines intersecting each other; a plurality of pixels provided corresponding to the intersection of the plurality of data lines and the plurality of scanning lines; and an image display area including the plurality of pixels. Prepared,
The image display area includes m scanning lines (m is a natural number of 2 or more) among the plurality of scanning lines, and a positive polarity to which a positive polarity image signal is applied to a reference potential. A negative polarity region that includes a region and m scanning lines that are continuous among the plurality of scanning lines, and a negative image signal is applied to the reference potential;
A scanning line driving circuit for supplying a scanning signal in a predetermined order to the scanning line of the positive polarity region and the scanning line of the negative polarity region;
Data for supplying the positive polarity image signal or the negative polarity image signal corresponding to the scanning line supplied with the scanning signal to the data line in the display period and supplying a predetermined potential in the off-sequence period. A driving method of an electro-optical device including a line driving circuit,
In the display period, the first start pulse and a second start pulse 1/2 that Do different vertical period phase one vertical period, the shift based on the first clock signal, based on said first start pulse Output a first scanning signal, and output a second scanning signal based on the second start pulse ,
In the off-sequence period, 1 a third start pulse and the fourth start pulse vertical period that Do different 1/2 vertical period phase, as well as shifts based on the second clock signal, the third start pulse A third scanning signal is output based on the fourth start signal, and a fourth scanning signal is output based on the fourth start pulse .
The pulse widths of the third start pulse and the fourth start pulse are half of the first start pulse and the second start pulse ,
The method of driving an electro-optical device, wherein the period of the second clock signal is half that of the first clock signal.   An electronic apparatus comprising the electro-optical device according to claim 1.

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