JP4179286B2 - Electro-optical device drive circuit, electro-optical device drive method, and electro-optical device including the same - Google Patents

Description

  The present invention relates to a driving circuit and a driving method used for an electro-optical device such as a liquid crystal device, and a technical field of the electro-optical device.

  An example of this type of electro-optical device is a liquid crystal device. As the driving method, inversion driving methods such as dot inversion, line inversion, and surface inversion are employed in order to prevent liquid crystal burn-in and deterioration. Each inversion driving method has advantages and disadvantages. However, in the case of dot inversion and line inversion, there is an advantage that crosstalk can be suppressed. However, since a reverse polarity potential is written to adjacent pixel electrodes, a horizontal electric field is generated between adjacent pixels. There is a problem that occurs. The lateral electric field disturbs the liquid crystal alignment and causes light leakage, and thus becomes a major factor in display quality deterioration such as a reduction in contrast ratio and a reduction in aperture ratio. Therefore, it is considered that the surface inversion driving method having little influence of the transverse electric field is advantageous for narrowing the pitch in the future.

  On the other hand, the surface inversion driving method has another problem. That is, in the case of surface inversion, since the applied voltage with respect to the intermediate potential is more or less asymmetrical between the positive polarity field (or positive polarity frame) and the negative polarity field (or negative polarity frame), the field period (or (Frame period) flicker occurs. Further, when focusing on a certain data line, assuming that the polarity inversion period is one field for all pixels to which a signal is supplied from the data line, an image signal having the same polarity is written in a predetermined field. At the moment of moving to the next field, the polarity of the image signal supplied to the data line is reversed. At this time, since the display area is scanned from the top to the bottom, the polarity of the image signal supplied to the data line in the upper pixel portion of the display area is almost during the holding period after the image signal is written. The same polarity as the signal potential to be held. On the other hand, in the lower pixel, an image signal having a polarity opposite to the held signal potential is applied to the data line for most of the holding period after the image signal is written. Thus, if there is a difference in the influence of the potential of the data line on the pixel electrode between the upper side and the lower side of the display area, there is a possibility that charge is leaked from the pixel portion on one side of the display area and proper display is not performed. is there. For example, the brightness to be displayed may be tilted up and down, or a black image may appear to have a shadow.

  As a means for ensuring the uniformity of the screen, for example, in Patent Document 1, one horizontal period is divided into a first period and a second period, and a drive pulse is supplied to the scanning line and the data line is supplied to the data line in the first period. A technique is proposed in which an image signal is applied to each pixel electrode by supplying an image signal, while an image signal having a reverse polarity to the data line is supplied to the data line without supplying a drive pulse to the scan line in the second period. Has been.

  In addition, the device for reducing the display noise generated during driving in this way in terms of time and space is also applied to methods other than the surface inversion method. For example, in Patent Document 2, regarding interpolating signals when NTSC interlace signals are displayed in a non-interlaced manner, the scanning speed is doubled and the same video signal is inverted with the same polarity pattern during one horizontal scanning period. However, a driving method is disclosed in which writing is performed on two lines and the writing line is shifted by one line for each field. In this technique, a DC component remains in each pixel portion due to the writing of image signals having the same polarity on the same line in two consecutive fields, so that display noise due to this DC component is reduced. Furthermore, it is configured to control the polarity inversion pattern.

JP-A-5-313608 Japanese Patent Laid-Open No. 10-253939

  However, the technique described in Patent Document 1 has a problem that the time that can be used for writing becomes half of the normal time and writing becomes insufficient. The technique described in Patent Document 2 makes it difficult to visually recognize flicker or the like to some extent, but it is considered that another idea is necessary to fundamentally improve display quality by reducing noise components. . Note that the above problem is not limited to the liquid crystal device, and the same problem may occur in principle in the case of an electro-optical device that applies a drive system that reverses the polarity.

  The present invention has been made in view of the above-described problems, for example, and can be applied to an electro-optical device driving circuit, an electro-optical device driving method, and a high-quality display capable of narrowing the pitch. An object of the present invention is to provide an electro-optical device.

In order to solve the above problems, a drive circuit for an electro-optical device according to the present invention includes a plurality of data lines and a plurality of scanning lines that extend so as to cross each other, and each of the data lines and the scanning lines is connected to the display surface. A driving circuit for an electro-optical device used to drive an electro-optical device including a plurality of pixel units that supply a pulse signal to each of the plurality of scanning lines, A scanning line driving unit that sequentially performs scanning; and a data line driving unit that supplies an image signal to the plurality of data lines. The scanning line driving unit and the data line driving unit have the display surface along the scanning line. The pixel portion constituting each of a plurality of first partial surfaces positioned oddly in a direction along the data line among a plurality of partial surfaces obtained by dividing each area by the dividing lines is a first portion. When the surface inversion drive is performed with a period of The pixel portion constituting each of the plurality of second partial surfaces positioned evenly among the plurality of partial surfaces is driven by surface inversion at a second period complementary to the first period, and the scanning is performed. The line driving unit alternately performs horizontal scanning on the pixel portion constituting the first partial surface and horizontal scanning on the pixel portion constituting the second partial surface, and at least one of the plurality of first partial surfaces. An area of the first partial surface is different from an area of at least one second partial surface of the plurality of second partial surfaces, and the plurality of first partial surfaces and the plurality of second partial surfaces are different from each other. Are divided so that the total area of the plurality of first partial surfaces and the total area of the plurality of second partial surfaces are substantially equal to each other.

  In the driving circuit for an electro-optical device according to the present invention, for example, an active matrix driving method is employed, and the data line driving unit outputs an image signal through the data line to the pixel unit column selected by the scanning line driving unit scanning the scanning line horizontally. To write data. The scanning line driving unit and the data line driving unit perform surface inversion driving for each partial surface in which one display surface is substantially equally divided in the horizontal direction. At that time, the adjacent partial surfaces are driven so as to have opposite polarities in each field period. Here, the “partial surface” refers to a region of at least two lines or more (that is, a region including two or more scanning lines) so as to perform surface inversion driving.

  The “surface inversion” according to the present invention is a driving method in which the polarity of an image signal is inverted every time a screen is formed (in other words, every time an image signal for one field is supplied). Corresponds to a surface inversion driving method in which 1 field is provided. However, the inversion period in this case is not a field period depending on the length of the image signal, but a display period of one screen. For example, when writing is performed at double speed and the same image is repeatedly written and displayed in a normal one field period, the polarity is reversed every time one field is supplied even if the same signal is supplied. Let In the present invention, in particular, horizontal scanning is sequentially performed on each partial surface, and surface inversion driving is performed. That is, each partial surface is surface-inverted with respect to an image signal corresponding to the portion.

  Further, the scanning line driving unit alternately performs horizontal scanning on the pixel units constituting the odd-numbered partial surfaces and the pixel units constituting the even-numbered partial surfaces. Here, when the scanning line driving unit “performs horizontal scanning alternately”, for example, if it is divided into two partial surfaces, it is performed alternately on these two partial surfaces, for example, divided into four partial surfaces. If so, it means that the four partial surfaces are sequentially performed. That is, the writing of the image signal is performed on each partial surface in parallel. Further, this horizontal scanning means that the positive partial surface and the negative partial surface are alternately performed. For this reason, the image signal supplied to each data line is converted into an alternating current, and the potential of the data line always fluctuates between positive and negative and is not biased to one polarity, thus affecting the charge accumulated in the pixel portion. You do n’t have to.

  The inventor of the present invention pays attention to the fact that the direct current component of the applied voltage in the data line is a factor causing leakage of accumulated charges, and prevents the direct current component from being superimposed on the data line as much as possible. The idea is to convert the image signal as much as possible. Here, since the polarities of the partial surfaces are also reversed, for example, when viewed from one data line, the pixel portion with respect to the upper partial surface is negative and the pixel portion with respect to the lower partial surface is positive. In the case of writing an image signal, if a positive image signal is applied to write the lower pixel portion, the potential of the data line becomes positive (+), and the negative (−) accumulated in the upper pixel portion. Attracts the charge. In addition, when the polarity of the data line is higher than the potential due to the accumulated charge, the same thing occurs when viewed in relative directions, except when the polarity is reversed. That is, it is considered that such a phenomenon frequently occurs in the same partial plane or between partial planes of the same polarity.

  Therefore, the present invention is combined with the above-described conventional problems (the amount of accumulated charge leaked at the lower side of the screen is increased by the amount of time affected by the data line potential and the luminance is inclined in the vertical direction). By driving so as to eliminate the DC signal component, it is possible to prevent leakage of accumulated charges and suppress display noise very well.

  In addition, since the display surface is divided and driven for such a purpose, the partial surface may be at least two surfaces corresponding to positive and negative polarities. Rather, if it is divided too finely, the boundary where the transverse electric field is generated increases, so it is considered preferable that the number of partial surfaces is small.

  As described above, according to the driving method of the present invention, the display surface is driven surface-inverted for each region so as to suppress the generation of the transverse electric field as much as possible, so that a high contrast ratio is maintained and a narrow pitch is achieved. Is possible. At the same time, so that the polarity of the image signal is alternately switched, horizontal scanning is alternately performed on the regions where the polarity of the image signal to be written at that time is different, so that the image signal is converted into an alternating current and the accumulated charge leaks in general. Can be prevented and appropriate display can be performed.

In the electro-optical device drive circuit according to the aspect of the invention, the scanning line drive unit and the data line drive unit may include the pixel unit including a dummy pixel that does not contribute to display among the plurality of partial surfaces. the sum of the plurality of first partial surfaces which are driven in one period, the difference between the sum of the plurality of second partial surfaces in which the said pixel portion including the dummy pixels are driven in the second period The area ratio is driven within 10%.

  In this aspect, the difference between the total area of the partial surface (including dummy pixels) where the image signal is written with a positive potential and the total area (including dummy pixels) of the partial surface where the image signal is written with a negative potential is a ratio. Within 10 percent. This is the upper limit of the difference in the size of the bipolar regions in order for the image signal to exhibit the above effect as an AC signal. If one polarity region is larger than the other, it is necessary to always write image signals of the same polarity continuously during one vertical scanning period. As a result, a DC component is generated in the image signal. The limit is within 10 percent in the area ratio of both. If the difference in size is larger than this, display noise is visually recognized as a manifestation of the leak amount of accumulated charge.

  In other words, in the surface inversion driving according to the present invention, since the polarity of the signal supplied to the data line is required, the difference between the two including the dummy pixels that do not contribute to the display is 10% in terms of the area ratio. It is preferable to keep it within.

  In another aspect of the drive circuit for an electro-optical device according to the aspect of the invention, the scanning line drive unit and the data line drive unit may be arranged so that signals having different polarities are continuously supplied to the data line alternately. In the blanking period, instead of or superimposing a surface inversion signal that performs polarity inversion continuously with the image signal supplied in the horizontal scanning period immediately before or immediately after the vertical blanking period, the data Supply to the wire.

  In this aspect, even during the vertical blanking period, a plane inversion signal that reverses the polarity in succession to the image signal supplied immediately before or after the horizontal scanning period is supplied to the data line, and the voltage of the data line is AC. Will continue during the vertical blanking period. That is, the “plane inversion signal” here is supplied so that alternating current is continuously applied to the data line, that is, it is supplied as a dummy signal corresponding to the image signal in the horizontal scanning period. Specifically, the surface inversion signal is a single pulse signal having a polarity different from that of the image signal supplied in the preceding and following horizontal scanning periods, or is continuously positive and negative with the image signal supplied in the preceding and following horizontal scanning periods. It may be a plurality of pulse signals (or AC signals) that perform polarity inversion. In this way, by alternating the voltage of the data line without interruption, it is possible to further enhance the effect of the data line alternating.

  In another aspect of the drive circuit for an electro-optical device according to the present invention, the scanning line driving unit and the data line driving unit may perform the same field on the pixel unit within a display period of one field by vertical scanning based on surface inversion driving. The image signal is repeatedly written a plurality of times.

  In this mode, by driving at double speed, an image to be displayed in that period is repeatedly written in each field period. As described above, in each field period, a predetermined image signal for one field is repeatedly displayed while being inverted.

  In the surface inversion driving, every time the field is switched, the pixel electrode is switched due to the difference in the amount of leakage according to the polarity of the accumulated charge caused by the characteristics of the thin film transistor for pixel switching (hereinafter referred to as “TFT”). In some cases, the potential of the above and below fluctuates up and down. This is visually recognized as a periodic luminance fluctuation corresponding to a field period of about 30 Hz, that is, flicker. Therefore, if the luminance fluctuation is doubled to, for example, about 60 Hz by doubling the drive, the frequency becomes sufficiently high so that it is not visually recognized. Therefore, in this case, the display quality can be further improved.

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

  According to the electro-optical device of the present invention, since the electro-optical device drive circuit of the present invention described above is provided, high-quality display is possible and at the same time a narrow pitch can be achieved. The electro-optical device includes various types of electronic devices such as a projection display device, a liquid crystal television, a mobile phone, an electronic notebook, a word processor, a viewfinder type or a direct view type video tape recorder, a workstation, a video phone, a POS terminal, a touch panel, and the like. It can be applied to equipment. In addition, the electro-optical device of the present invention can realize, for example, an electrophoretic device such as electronic paper or a display device (Field Emission Display and Surface-Conduction Electron-Emitter Display) using an electron-emitting device. is there.

In order to solve the above-described problem, the electro-optical device driving method according to the present invention includes a plurality of data lines and a plurality of scanning lines extending to intersect each other, each connected to the data lines and the scanning lines, an electro-optical apparatus driving method applied to an electro-optical device including a plurality of pixel portions constituting a plurality of each area is formed by split by a dividing line which the display surface along the scan line The pixel portions constituting each of the plurality of first partial surfaces positioned oddly in the direction along the data line among the partial surfaces of the plurality of partial surfaces are subjected to surface inversion driving in a first period, and the plurality of portions The pixel portions constituting a plurality of second partial surfaces positioned evenly among the surfaces are surface-inverted driven in a second cycle complementary to the first cycle, and the scanning line driver is Horizontal scanning and previous scanning for the pixel parts constituting one partial surface Horizontal scanning is alternately performed on the pixel portions constituting the second partial surface, and the area of at least one first partial surface of the plurality of first partial surfaces and at least one first of the plurality of second partial surfaces. The areas of the two partial surfaces are different from each other, and the plurality of first partial surfaces and the plurality of second partial surfaces are the total area of the plurality of first partial surfaces and the plurality of second partial surfaces. The total area is divided so as to be substantially equal to each other.

  In the electro-optical device driving method of the present invention, as described above in the section of the electro-optical device driving circuit of the present invention, surface inversion driving is performed for each partial surface in which one display surface is substantially equally divided in the horizontal direction. Do. At that time, the adjacent partial surfaces are driven so as to have opposite polarities in each field period. Further, the horizontal scanning is alternately performed on the positive-polarity partial surface and the negative-polarity partial surface, and the image signal supplied to each data line is converted into an alternating current. For this reason, the potential of the data line always fluctuates between positive and negative and does not deviate to one polarity, so that the charge accumulated in the pixel portion is not affected.

  Therefore, according to the driving method for an electro-optical device of the present invention, the lateral electric field can be suppressed by performing surface inversion driving for each region, so that a reduction in the contrast ratio and a reduction in pixel aperture ratio due to the installation of a light shielding film are prevented. Narrow pitch can be achieved. In addition, display noise due to charge leakage can be prevented, and display quality can be greatly improved.

  Such an operation and other advantages of the present invention will become apparent from the embodiments described below.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. In the following embodiments, the electro-optical device of the invention is applied to a liquid crystal device.

<1: First Embodiment>
First, a first embodiment according to the electro-optical device of the invention will be described with reference to FIGS.

<1-1: Configuration of Electro-Optical Device>
First, the configuration of the electro-optical device according to the present embodiment will be described with reference to FIGS. 1 to 4. FIG. 1 is a plan view of the electro-optical device when the TFT array substrate is viewed from the counter substrate side together with the components formed thereon, and FIG. 2 is a cross-sectional view taken along line HH ′ of FIG. FIG. 3 illustrates an equivalent circuit of the pixel unit in the electro-optical device according to the present embodiment. FIG. 4 is a block diagram including a drive circuit unit.

  1 and 2, in the electro-optical device according to the present embodiment, a TFT array substrate 10 and a counter substrate 20 are disposed 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 provided with a sealing material 52 provided in a seal region positioned around the image display region 10a. Are bonded to each other.

  The sealing material 52 is made of, for example, an ultraviolet curable resin, a thermosetting resin, or the like for bonding the two substrates, and is applied on the TFT array substrate 10 in the manufacturing process and then cured by ultraviolet irradiation, heating, or the like. It is. Further, in the sealing material 52, a gap material such as glass fiber or glass beads for dispersing the distance (inter-substrate gap) between the TFT array substrate 10 and the counter substrate 20 to a predetermined value is dispersed. That is, the electro-optical device according to the present embodiment is suitable for a small and enlarged display for a projector light valve.

  A light-shielding frame light-shielding film 53 that defines the frame area of the image display area 10a is provided on the counter substrate 20 side in parallel with the inside of the seal area where the sealing material 52 is disposed. However, part or all of the frame light shielding film 53 may be provided as a built-in light shielding film on the TFT array substrate 10 side.

  A data line driving circuit 101 and an external circuit connection terminal 102 are provided along one side of the TFT array substrate 10 outside the region where the sealing material 52 is disposed in the peripheral region located around the image display region 10a. It has been. The scanning line driving circuit 104 is provided along two sides adjacent to the one side so as to be covered with the frame light shielding film 53. Further, in order to connect the two scanning line driving circuits 104 provided on both sides of the image display area 10 a in this way, a plurality of the pixel lines are covered along the remaining side of the TFT array substrate 10 and covered with the frame light shielding film 53. Wiring 105 is provided.

  In addition, vertical conduction members 106 that function as vertical conduction terminals between the two substrates are disposed at the four corners of the counter substrate 20. On the other hand, the TFT array substrate 10 is provided with vertical conduction terminals in a region facing these corner portions. Thus, electrical conduction can be established between the TFT array substrate 10 and the counter substrate 20.

  In FIG. 2, on the TFT array substrate 10, a pixel electrode 9a is formed on a pixel switching TFT and various wirings, and an alignment film is formed thereon. On the other hand, on the counter substrate 20, in addition to the counter electrode 21, a lattice-shaped or striped light-shielding film 23 is formed, and an alignment film is further formed thereon. 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.

  On the TFT array substrate 10, in addition to the data line driving circuit 101, the scanning line driving circuit 104, etc., for example, a sampling circuit that samples the image signal on the image signal line and supplies it to the data line, a plurality of data lines A precharge circuit for supplying a precharge signal of a predetermined voltage level in advance of the image signal, an inspection circuit for inspecting quality, defects, etc. of the electro-optical device during manufacture or at the time of shipment may be formed. .

  As shown in FIG. 3, in the image display area 10a, a plurality of scanning lines 3a and a plurality of data lines 6a are arranged crossing each other, and each of the scanning lines 3a and the data lines 6a is arranged between the lines. A pixel portion selected by the above 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 3a, 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 described later, 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.

  This electro-optical device adopts, for example, 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 3a in the order described later. Thus, the data signals S1, S2,..., Sn from the data line driving circuit 101 (see FIG. 1) are applied through the data line 6a to the horizontal selected pixel portion column in which the TFT 30 is turned on. Yes. At this time, the data signals S1, S2,..., Sn may be supplied sequentially to the data lines 6a, or 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. Since the TFT array substrate 10 is disposed 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 region that is partitioned and arranged as described above. Thus, the amount of transmitted light between the two substrates is controlled for each pixel region, and the image is displayed in gradation. Further, the image signal held in each pixel area at this time is prevented from leaking by the storage capacitor 70.

  As shown in FIG. 4, the drive circuit unit 60 of the electro-optical device according to the present embodiment includes the controller 61, the first frame memory 62, the second frame, in addition to the data line drive circuit 101 and the scanning line drive circuit 104 described above. A frame memory for two screens of the memory 63, a DA converter 64, and the like are included. The controller 61 receives a vertical synchronization signal Vsync, a horizontal synchronization signal Hsync, and an image signal DATA. The controller 61 controls the operation timing of each component based on the vertical synchronization signal Vsync and the horizontal synchronization signal Hsync, controls the writing / reading of the first frame memory 62 and the second frame memory 63, and writes the scanning line 3a. The corresponding image signal DATA 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 image signal DATA for one frame externally input to one side, for example, every frame, and the image signal DATA stored from the other side. Is used to output for display. The DA converter 64 DA-converts the image signal DATA read from the frame memory and outputs it to the data line driving circuit 101. The data line driving circuit 101 applies the data signal Sx to the corresponding data line 6a as an output based on this input signal.

  Although specifically described later, the scanning line driving circuit 104 can perform basic line-sequential horizontal scanning by inputting a clock signal CLK and an inverted clock signal CLK ′ from the controller 61. In addition, here, although one drive circuit is used, two start pulses are generated and output at the same time, and enable signals ENB1 and ENB2 for shifting the output timings of these scan signals are input. In addition, it is possible to adopt a driving method in which the scanning signal Gx is applied to the scanning line 3a in the order described below.

<1-2: Driving Method of Electro-Optical Device>
Next, a driving method of such an electro-optical device will be described with reference to FIGS. 5 and 6 are diagrams for conceptually explaining the driving method of the present embodiment. FIG. 7 shows the change in polarity on the screen in time series. FIG. 8 shows an arbitrary 1 It shows the image of the screen when viewing the moment of the horizontal period. FIG. 9 shows a change in the amount of charge leakage in the pixel portion with respect to the difference in area of regions driven with mutually complementary polarities.

  In the present embodiment, as shown in FIG. 5, the “surface inversion driving” according to the present invention is performed with the pixel portions of the two partial surfaces 201 and 202 obtained by dividing one screen substantially vertically above and below in a period complementary to each other. As an example, field inversion driving is performed. Here, this period is a half field. That is, the scanning line driving circuit 104 and the data line driving circuit 101 are driven at a double speed, and the writing of the data signal Sx to the partial surfaces 201 and 202 is performed for two screens in one field period. Specifically, one field data is divided into first and second field data having different polarities, and these are overwritten while being shifted by 1/2 vertical period. This can be done by using the frame memories 62 and 63. At this time, the data line driving circuit 101 inverts the polarity of the data signal Sx in a 1/2 field cycle, and at the same time, makes the polarity of the data signal Sx different between the partial surface 201 and the partial surface 202 in one screen. To drive.

  Further, as shown in FIG. 6, horizontal scanning of each screen is alternately performed by the pixel portion of the partial surface 201 and the pixel portion constituting the partial surface 202. That is, the data signal Sx is written in parallel to the partial surfaces 201 and 202. FIG. 7 shows this state in time series.

  In FIG. 7, for example, in the first horizontal period, the 2m-th scanning line 3a is scanned by the scanning signal G2m, and the negative potential data signal Sx is written. In the second horizontal period, the (m + 1) th scanning line 3a is scanned by the scanning signal Gm + 1, and the positive potential data signal Sx is written in the pixel portion that was in the negative potential in the first horizontal period. In the third horizontal period, the first scanning line 3a is scanned by the scanning signal G1, and the negative potential data signal Sx is written in the pixel portion which is the positive potential in the first and second horizontal periods. Thereafter, such a selective writing operation is repeated. Therefore, when the scanning of half of the screen, that is, the partial surfaces 201 and 202 is completed, the positive polarity region and the negative polarity region are completely reversed, and one screen is rewritten. According to this method, if the entire screen is scanned, rewriting is performed twice, and as a result, one vertical period is halved with respect to the input image signal.

  As a result, as shown in FIG. 8, when focusing on one horizontal period, for example, the pixel portion scanned by the scanning signals G3 to Gm + 2 becomes a region in which positive potential data is written, and the scanning signals G1 to G2 and Gm + 3 A state where the screen is divided into a positive polarity region and a negative polarity region so that the pixel portion scanned by ~ G2m is a region where negative potential data is written (hereinafter simply referred to as a negative polarity region). It becomes.

  In FIG. 8, the boundaries 203BR1 and 203BR2 between the positive polarity region and the negative polarity region move from top to bottom according to vertical scanning from top to bottom in the screen. That is, since the boundaries 203BR1 and 203BR2 where the image quality deteriorates due to the occurrence of the transverse electric field are scanned in-plane vertically without stopping at one place, the image quality deterioration due to the transverse electric field is hardly noticeable visually. .

  As described above, in this embodiment, the positive polarity region and the negative polarity region having a half area of the screen are inverted in one vertical period, and the surface inversion driving is performed for each of the partial surfaces 201 and 202. Is done. In one vertical period, an arbitrary pixel portion and an adjacent pixel portion have a reverse polarity potential for a time of 2/2 m, but most of the remaining time (2m−2) / 2 m has the same polarity potential. Therefore, the alignment defect in the liquid crystal layer 50 due to the transverse electric field hardly occurs.

  On the other hand, since the signal polarity on the data line 6a side is reversed between the partial surface 201 and the partial surface 202, the TFT 30 on the upper side and the lower side of the screen as in the case of driving by the conventional surface inversion method. There is no large difference in the amount of charge leakage, and uneven display due to the location of the screen can be avoided.

  Further, here, since the horizontal scanning is alternately performed on the positive-polarity partial surface and the negative-polarity partial surface, the data signal Sx supplied to each data line 6a is converted into an alternating current. For this reason, since the potential of the data line 6a always fluctuates between positive and negative and does not bias to one polarity, the possibility of leaking the charge accumulated in the storage capacitor 70 of the pixel portion is reduced.

  For these reasons, it is desirable that the positive and negative areas, that is, the areas of the partial surfaces 201 and 202 are substantially equal. Since the polarity of the signal supplied to the data line is substantially required, the difference between the two including the dummy pixels that do not contribute to the display is actually suppressed within 10% in terms of the area ratio. It is preferable. Further, even when one polarity scan is in the vertical blanking period and the other scan is in the display area, the signal supplied to the vertical blanking data line is also the other so as not to impair the data line AC. It is desirable to be within the video signal level of the reverse polarity of the above signal.

  FIG. 9 shows the amount of charge leakage in the pixel portion with respect to the difference in area of regions driven with mutually complementary polarities, such as the partial surfaces 201 and 202. Thus, it is known that the amount of charge leakage increases in proportion to the difference in the total area between regions having different polarities. When the leak amount exceeds the threshold Lth, it is visually recognized as flickering of the screen. Further, suppressing the leak amount to be equal to or less than the threshold value Lth is equivalent to suppressing the difference in the area within 10% and converting the image signal to AC.

  In the present embodiment, the scanning frequency becomes 100 Hz or more, which is twice the input image signal frequency, by the double speed driving, so that flicker that can be recognized by human vision can be reliably suppressed.

  Next, specific means for realizing this driving method will be described with reference to FIGS.

  FIG. 10 illustrates a configuration example of the scanning line driving circuit 104 when the number of scanning lines is four, and FIG. 11 is a timing chart in the scanning line driving circuit 104 illustrated in FIG. 12 shows a configuration of the NAND circuit 67 in the scanning line driving circuit 104, and FIG. 13 shows a truth table of the NAND circuit 67. 14 and 15 show a specific layout configuration of the NAND circuit 67. FIG.

  As shown in FIG. 10, the scanning line driving circuit 104 receives, for example, a shift register 66 to which the clock signal CLK and the inverted clock signal CLK ′ are input from the controller 61 shown in FIG. And an output control unit 69 composed of 2m logic circuits corresponding to 2m scanning lines 3a. The logic circuit includes, for example, a NAND circuit 67 and a NOT circuit 68, and an output from the shift register 66 and an enable signal ENB1 or ENB2 are input to each NAND circuit 67.

  The wiring of the enable signal ENB1 is connected to the first NAND circuit 67 on the partial surface 201, but is connected to the second (that is, fourth overall) NAND circuit 67 on the partial surface 202. On the contrary, the wiring of the enable signal ENB2 is connected to the second and first (that is, third as a whole) NAND circuit 67, and the enable signals ENB1 and ENB2 are connected in order of connection with the NAND circuit 67. It has become different. Therefore, by configuring the scanning line driving circuit 104 in this way, the electro-optical device can be appropriately driven.

  As shown in FIG. 11, the start pulses SR1 to SR4 from the shift register 66 are output to the respective scanning lines 3a at the same timing so that the partial surfaces 201 and 202 are simultaneously horizontally scanned. That is, the start pulses SR1 and SR3 corresponding to the first scanning line 3a of each of the partial surfaces 201 and 202 and the start pulses SR2 and SR4 corresponding to the second scanning line 3a are alternated every two horizontal periods. Is output. On the other hand, the enable signals ENB1 and ENB2 rise alternately every horizontal period. Therefore, the start pulse output at the rising timing is selected by the logic circuit and is output to the scanning line 3a as a scanning signal. As a result, the scanning signals G1 to G4 are output in the order of the scanning signals G1, G3, G2, and G4 as shown in the figure, and the horizontal scanning as described above is realized (see FIG. 6 or FIG. 7).

  Hereinafter, the configuration of the NAND circuit 67 of this embodiment will be described.

  As shown in FIG. 12, each of the NAND circuits 67 includes a CMOS (Complementary Metal-Oxide Semiconductor) inverter composed of a p-type MOSFET 67A and an n-type MOSFET 67B, that is, an AND circuit configured as a “complementary inverter”, and an output side terminal thereof. And a NOT circuit 67C connected to the circuit. The p-type MOSFET 67A and the n-type MOSFET 67B are connected in series between the signal line of the enable signal ENB1 or ENB2 and the ground, and are configured so that the inverted signal SR ′ of the start pulse SR is input to the gate terminal. Has been. The inverted signal SR ′ may be output by inverting the start pulse SR. However, assuming that the signal in the shift register 66 is inverted, the internal signal of the shift register 66 is regarded as the start pulse SR, and the output from the shift register 66 is the inverted signal. If the configuration becomes SR ′, it can be configured more easily. Note that the NOT circuit 67C can also be configured by a CMOS inverter, and may have the same circuit configuration as the AND circuit.

  FIG. 13 is a truth table of this AND circuit. Here, when the input start pulse SR is “High” and the enable signal ENB is “Low”, the gate voltages of the MOSFETs 67A and 67B are “Low”, the p-type MOSFET 67A is turned on, and the n-type MOSFET 67B is turned off. Become. Therefore, the potential 0V of the enable signal ENB is applied to the conductive p-type MOSFET 67A, but a threshold voltage (for example, 1.5V) is generated between the source and drain of the p-type MOSFET 67A. Is not 0V but has an effective value of about 1.5V, for example.

  However, in this case, the NOT circuit 67C provided at the subsequent stage of the point O has a threshold voltage of about 7.5V as an inverter. Therefore, the fluctuation of the low voltage of about 1.5V can be ignored. The signal output in the above case can also be handled as “Low”. The threshold voltage 7.5V is realized if the NOT circuit 67C is a normal inverter driven by a power supply voltage 15V, for example. In other words, the NAND circuit 67 is applied to a high voltage circuit system called an output side circuit of the scanning signal Gx, thereby ensuring normal operation.

  Further, the scanning line driving circuit 104 of the present embodiment is configured with a circuit layout as shown in FIG. 14, for example. That is, the formation regions of the shift register 66 and the output control unit 69 are adjacent to the image display region 10a, and unit circuits corresponding to the respective scanning lines 3a are formed in the unit region W. The NAND circuit 67 is formed, for example, with the layout shown in FIG. 15 so as to fit in the unit region W of the output control unit 69 indicated by hatching in the drawing. FIG. 15 shows the configuration of a CMOS that is an AND circuit in the NAND circuit 67.

  A normal NAND circuit is composed of 6 gates, but it is difficult to form it in the thin unit region W. In particular, as the pixel pitch is reduced, the width of the unit region W is also narrowed. For example, when the pitch is about 10 μm, at most, only a space enough to form two gates side by side is left. Therefore, as in the present embodiment, the output control unit 69 has a very simple configuration, so that the electro-optical device can be easily manufactured and the pitch can be further reduced. Further, since the number of gates is small, it is possible to reduce power consumption in the drive circuit unit 60.

  In addition, as shown in FIG. 15, the AND circuit here has a two-cycle structure in which two unit circuits are mirror-symmetrical with respect to the I line. Therefore, it can be efficiently built and the pitch of the device can be reduced.

<2: Second Embodiment>
Hereinafter, a second embodiment according to the electro-optical device of the invention will be described with reference to FIGS. 16 to 18.

  FIG. 16 illustrates a configuration of a main part of the electro-optical device according to the second embodiment. FIG. 17 is a timing chart showing the driving method of the electro-optical device, and FIG. 18 shows the state of the driving screen to which data is written in time series corresponding to the timing chart of FIG. Is.

  The electro-optical device according to the present embodiment has substantially the same basic configuration as the first embodiment, but differs in that the screen is divided into four partial surfaces 401 to 404 to perform surface inversion driving. Accordingly, the same components as those in the first embodiment are denoted by the same reference numerals, and the description thereof is omitted as appropriate.

  The partial surfaces 401 to 404 are regions in which adjacent surfaces are driven by field inversion with a complementary cycle, and are divided so that four scanning lines 3a are provided. That is, the areas of the partial surfaces 401 to 404 are equal to each other. The scanning line driving circuit 414 generates and outputs four start pulses SR at the same time while being a single driving circuit by the shift register 466, and four enable signals ENB1 to ENB4 for shifting the output timing of the scanning signal are output control units. 469 is input. A total of four start pulses SR, one for each of the partial surfaces 401 to 404, are output with the horizontal scanning period as the pulse width. The enable signals ENB1 to ENB4 are output with a quarter horizontal scanning period as a pulse width and shifted in timing in one horizontal scanning period.

  In the driving method shown in FIG. 17, horizontal scanning is sequentially performed on the pixel portions of the partial surfaces 401 to 404. For example, in the first horizontal period, the 1m-th scanning line 3a is scanned by the scanning signal G1m, and the positive potential data signal Sx is written in the pixel portion. In the second horizontal period, the fifth scanning line 3a is scanned by the scanning signal G5, and the negative potential data signal Sx is written in the pixel portion. In the third horizontal period, the ninth scanning line 3a is scanned by the scanning signal G9, and the positive potential data signal Sx is written in the pixel portion. In the fourth horizontal period, the thirteenth scanning line 3a is scanned by the scanning signal G13, and the negative potential data signal Sx is written in the pixel portion. Thereafter, such selective writing operation is sequentially performed on the partial surfaces 401 to 404.

  The scanning signal Gx at this time is different from each other by shifting the output timings of the four start pulses SR1, SR5, SR9, and SR13 by the enable signals ENB1 to ENB4 and simultaneously setting each output period to 1/4. Horizontal scanning of the surfaces 401 to 404 is performed in parallel. On the other hand, the data line driving circuit 101 reverses the polarity of the data signal Sx in synchronization with the horizontal scanning, and at the same time, the partial surface 401 and 403 and the partial surface 402 and 404 have different polarities on the data surface Sx on one screen. To drive. As a result, the polarities of the partial surfaces 401 to 404 are driven so as to alternate with each other (see FIG. 18).

  As described above, since the horizontal scanning is alternately performed on the positive-polarity partial surface and the negative-polarity partial surface, the data signal Sx supplied to each data line 6a is converted into an alternating current. For this reason, since the potential of the data line 6a always fluctuates between positive and negative and does not bias to one polarity, the possibility of leaking the charge accumulated in the storage capacitor 70 of the pixel portion is reduced.

  Also in this embodiment, since the surface inversion driving is performed for each of the partial surfaces 401 to 404, the alignment defect in the liquid crystal layer 50 due to the transverse electric field hardly occurs. In addition, there is no great difference in the amount of charge leakage from the TFT 30 between the upper side and the lower side of the screen, and display unevenness due to the location of the screen can be avoided.

  Then, as shown in FIG. 18, when the scanning of 1/4 of the screen, that is, the partial surfaces 401 to 404 is completed, the positive polarity region and the negative polarity region are completely reversed, and rewriting for one screen is performed. It will be broken. According to this method, if the entire screen is scanned, rewriting is performed four times. Therefore, if the scanning line driving circuit 414 and the data line driving circuit 101 are driven at a quadruple speed, 1 vertical to the input image signal. The period is set to ¼, and flicker can be reliably suppressed.

  As described above, according to the present embodiment, as in the first embodiment, it is possible to prevent a decrease in contrast ratio and a decrease in pixel aperture ratio and to reduce the pitch. In addition, display noise due to charge leakage can be prevented, and display quality can be greatly improved. Other effects are the same as those in the first embodiment.

<3: Modification>
Next, a modification of the above embodiment will be described with reference to FIGS.

  In the above embodiments, the areas of the partial surfaces are the same, but the sizes of the partial surfaces are not necessarily equal. Even in such a case, if the sum of the areas of the partial surfaces to be inverted and driven with a complementary period is made substantially equal to each other, the data signals can be converted into alternating current by alternately scanning the two types of partial surfaces horizontally. Can be supplied to the pixel portion.

  FIG. 19 shows a modification in which the screen is divided into three parts as a specific example. In this case, the screen is divided into the partial surface 201 and the partial surfaces 202a and 202b, and is inverted and driven with a period complementary to each other. Here, the area S1 of the partial surface 201 and the total area S2a + S2b of the partial surfaces 202a and 202b are set equal. Therefore, the number of scanning lines of these two types of partial surfaces is the same, and the two types of partial surfaces can be alternately scanned horizontally. Various horizontal scanning orders can be considered. For example, as shown in the drawing, the partial surface 202a → the partial surface 202 → the partial surface 202b may be sequentially performed, and the respective partial surfaces may be sequentially scanned from the top.

  FIG. 20 shows a modified example in which the screen is driven in seven divisions. In this case, the screen is divided into seven partial surfaces, and the adjacent partial surfaces are inverted and driven with a period complementary to each other. Further, the total area of the two types of partial surfaces divided by the drive cycle, that is, S1a + S1b + S1c +... And S2a + S2b + S2c +. Therefore, the number of scanning lines of these two types of partial surfaces is the same, and horizontal scanning can be performed alternately. In addition to the regular scanning method as in the previous modification, the horizontal scanning sequence should be performed randomly as shown in the figure (however, the partial planes having different polarity inversion periods are always selected alternately). You can also.

<4: Electronic equipment>
Next, a specific example of a projection type color display device will be described with reference to FIG. 21 as an electronic apparatus using the electro-optical device described in detail above as a light valve. FIG. 21 is a schematic cross-sectional view of the projection type color display device.

  In FIG. 21, a liquid crystal projector 1100 as an example of a projection type color display device in the first or second embodiment prepares three liquid crystal modules including a liquid crystal device in which a drive circuit is mounted on a TFT array substrate. It is configured as a projector used as a light valve 100R, 100G, and 100B for use. In the liquid crystal projector 1100, when projection light is emitted from a lamp unit 1102 of a white light source such as a metal halide lamp, light components R, G, and R corresponding to the three primary colors of RGB are obtained by three mirrors 1106 and two dichroic mirrors 1108. Divided into B, the light valves are guided to the light valves 100R, 100G and 100B corresponding to the respective colors. In particular, the B light is guided through a relay lens system 1121 including an incident lens 1122, a relay lens 1123, and an exit lens 1124 in order to prevent light loss due to a long optical path. The light components corresponding to the three primary colors modulated by the light valves 100R, 100G, and 100B are synthesized again by the dichroic prism 1112 and then enlarged and projected as a color image on the screen 1120 via the projection lens 1114.

  In this projection type color display device, by using the electro-optical device of the above-described embodiment, high-definition display with extremely little noise such as flicker and excellent uniformity can be achieved.

  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 circuit and the electro-optical device driving method, and the electro-optical device are also included in the technical scope of the present invention. For example, in the above-described embodiment, an example in which the screen is divided into two partial surfaces or four partial surfaces and driven as the partial surface to be reversed with a complementary period has been described. However, the number of divisions is not limited to this. Further, the number of divisions may be increased. However, as the number of divisions is increased, the boundary between the partial surfaces where the transverse electric field is generated increases.

  Furthermore, in the above embodiment, an active matrix type liquid crystal device using TFTs has been described as an example. However, the present invention is not limited to this, and for example, a pixel switching element using a TFD (Thin Film Diode), The present invention can also be applied to a passive matrix type. An electro-optical device that can perform matrix driving with temporal or spatial polarity reversal other than the liquid crystal device is also within the scope of the present invention. Examples of such an electro-optical device include an electroluminescence device, an electrophoresis device, and a display device (Field Emission Display and Surface-Conduction Electron-Emitter Display) using an electron-emitting device.

It is a top view which shows the whole structure of an electro-optical apparatus. It is H-H 'sectional drawing of FIG. 2 is an equivalent circuit of various elements, wirings, and the like in a plurality of pixel portions formed in a matrix that forms an image display region of an electro-optical device. 1 is a block diagram illustrating a configuration related to a drive system of an electro-optical device according to a first embodiment. FIG. FIG. 5 is a diagram for explaining a driving method of the electro-optical device according to the first embodiment. FIG. 5 is a diagram for explaining a driving method of the electro-optical device according to the first embodiment. FIG. 5 is a diagram for explaining a driving method of the electro-optical device according to the first embodiment. FIG. 5 is a diagram for explaining a driving method of the electro-optical device according to the first embodiment. FIG. 5 is a diagram for explaining a driving method of the electro-optical device according to the first embodiment. FIG. 3 is a circuit diagram illustrating a specific configuration of a drive circuit of the electro-optical device according to the first embodiment. 6 is a timing chart for explaining a driving method of the electro-optical device according to the first embodiment. FIG. 11 is a circuit diagram showing a specific configuration of a NAND circuit in the drive circuit shown in FIG. 10. 13 is a truth table of the NAND circuit shown in FIG. It is a figure which shows the specific circuit arrangement | positioning of the drive circuit shown in FIG. FIG. 13 is a diagram showing a partial circuit layout of the NAND circuit shown in FIG. 12. FIG. 10 is a block diagram illustrating a configuration related to a drive system of an electro-optical device according to a second embodiment. 12 is a timing chart for explaining a driving method of the electro-optical device according to the second embodiment. FIG. 10 is a diagram for explaining a driving method of an electro-optical device according to a second embodiment. FIG. 10 is a diagram for explaining a driving method of an electro-optical device according to a modification of the embodiment. FIG. 10 is a diagram for explaining a driving method of an electro-optical device according to a modification of the embodiment. FIG. 3 is a schematic cross-sectional view illustrating an example of a projection color display device as an embodiment of an electronic apparatus to which the electro-optical device of the invention is applied.

Explanation of symbols

3a ... Scanning line, 6a ... Data line, 9a ... Pixel electrode, 10a ... Image display area, 30 ... TFT, 400 ... Capacitive wiring, 60 ... Drive circuit section, 66,466 ... Shift register, 67A, 67B ... MOSFET, 67C ... NOT circuit, 69, 469 ... Output controller, 70 ... Storage capacitor, 101 ... Data line drive circuit, 104, 414 ... Scan line drive circuit, 201, 202 ... Partial plane, 401-404 ... Partial plane, W ... Unit Area, G1 to G2m: scanning signal, SR: start pulse, ENB: enable signal.

Claims (6)

To drive an electro-optical device comprising a plurality of data lines and a plurality of scanning lines extending intersecting each other, and a plurality of pixel portions each connected to the data lines and the scanning lines and constituting a display surface A drive circuit for an electro-optical device used,
A scanning line driving unit that sequentially supplies horizontal scanning of the pixel unit by supplying a pulse signal to each of the plurality of scanning lines;
A data line driving unit for supplying an image signal to the plurality of data lines,
The scanning line driving unit and the data line driving unit are odd-numbered in a direction along the data line among a plurality of partial surfaces in which each area is divided by a dividing line along the scanning line. The pixel portions constituting each of the plurality of first partial surfaces that are positioned are driven by surface inversion at a first period, and the plurality of second partial surfaces that are positioned evenly among the plurality of partial surfaces. The pixel portions constituting each of the pixel parts are driven by surface inversion with a second period complementary to the first period,
The scanning line driving unit alternately performs horizontal scanning on the pixel portion constituting the first partial surface and horizontal scanning on the pixel portion constituting the second partial surface,
An area of at least one first partial surface of the plurality of first partial surfaces and an area of at least one second partial surface of the plurality of second partial surfaces are different from each other,
The plurality of first partial surfaces and the plurality of second partial surfaces are divided so that a total area of the plurality of first partial surfaces and a total area of the plurality of second partial surfaces are substantially equal to each other. A drive circuit for an electro-optical device.   The scanning line driving unit and the data line driving unit include the plurality of first partial surfaces in which the pixel unit including dummy pixels that do not contribute to display is driven in the first period. And the difference between the sum of the plurality of second partial surfaces in which the pixel portion including the dummy pixels is driven in the second period is driven to be within 10% in terms of area ratio. The drive circuit for an electro-optical device according to claim 1.   The scanning line driving unit and the data line driving unit are arranged immediately before or immediately after the vertical blanking period in a vertical blanking period so that signals having different polarities are continuously supplied to the data line alternately. 3. A surface inversion signal for performing polarity inversion continuously with an image signal supplied during the horizontal scanning period is supplied to the data line in place of or superimposed on the image signal. The driving circuit for an electro-optical device according to the description. The scanning line driving unit and the data line driving unit repeatedly write an image signal of the same field to the pixel unit a plurality of times within a display period of one field by vertical scanning based on surface inversion driving. The drive circuit for an electro-optical device according to any one of claims 1 to 3.   An electro-optical device comprising the electro-optical device drive circuit according to claim 1. Electricity applied to an electro-optical device comprising a plurality of data lines and a plurality of scanning lines extending intersecting each other, and a plurality of pixel portions each connected to the data lines and the scanning lines and constituting a display surface A driving method for an optical device comprising:
Each of the plurality of first partial surfaces positioned oddly in the direction along the data line among the plurality of partial surfaces obtained by dividing the area of the display surface by the dividing lines along the scanning lines. The pixel portion constituting the surface is driven in a surface inversion at a first cycle, and the pixel portions constituting a plurality of second partial surfaces positioned evenly among the plurality of partial surfaces are arranged at the first cycle. And surface inversion driving in a second period complementary to
The scanning line driving unit alternately performs horizontal scanning on the pixel portion constituting the first partial surface and horizontal scanning on the pixel portion constituting the second partial surface,
An area of at least one first partial surface of the plurality of first partial surfaces and an area of at least one second partial surface of the plurality of second partial surfaces are different from each other,
The plurality of first partial surfaces and the plurality of second partial surfaces are divided so that a total area of the plurality of first partial surfaces and a total area of the plurality of second partial surfaces are substantially equal to each other. A driving method for an electro-optical device.

Images