JP2006053397A - Electro-optical device, electronic equipment and driving method and inspection method of the electro-optical device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To easily conduct a flicker inspection while maintaining high display quality of an electro-optical device. <P>SOLUTION: The electro-optical device is provided with a plurality of pixel sections which are arranged in an image display region and a driving section. During an image displaying time in which an image is displayed in an image display region, the driving section reverses the polarities of image signals with respect to a reference voltage and supplies the signals to the plurality of the pixel sections for every 1/n image display interval where one image display interval beforehand controlled as an one image display interval is divided by n (where n is an natural number ≥2) so that the polarity of the image display region is reversed for 1/n image display interval. During an inspection time in which an inspection image is to be displayed to inspect the amount of deviation from an optimum value of the reference voltage, the driving section reverses the polarity of the image display region for every one image display interval. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a technical field of an electro-optical device such as a liquid crystal device and an electronic apparatus including the electro-optical device. Further, the present invention relates to a technical field of such an electro-optical device driving method and an inspection method used for flicker inspection of the electro-optical device.

  An example of this type of electro-optical device is a liquid crystal device. The driving system is devised to reduce display defects that occur during driving. For example, in order to prevent display screen flicker, liquid crystal burn-in, and deterioration, a polarity inversion driving method is generally employed. In the surface inversion driving method, the polarity of the image signal is inverted for each field or frame, that is, for each screen. In the row inversion driving method and the column inversion driving method, the polarity of the image signal is further inverted for each row and each column while performing surface inversion with a frame or field period.

  However, in the surface inversion driving, the applied voltage 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). Period) flicker occurs.

  As a flicker prevention method, a double speed driving method is known in which an image signal for one frame is stored in a memory, and a driving frequency is increased by compressing and reading a time axis (see, for example, Patent Document 1). This utilizes the fact that when the driving frequency is increased, flicker cannot be visually recognized by human eyes. Note that such double speed driving shortens the voltage application time per time for the liquid crystal, which can contribute to reducing crosstalk in the display image, deterioration of the liquid crystal, and burn-in.

Japanese Patent No. 2605261

  However, when the double speed driving method is employed, there is a technical problem that visual flicker inspection becomes difficult due to the above reasons. In the flicker inspection, the deviation amount from the optimum value of the reference voltage applied to the counter electrode is inspected by the size of the flicker.

  The present invention has been made in view of the above-described problems, for example. An electro-optical device and an electronic apparatus capable of easily performing a flicker inspection while maintaining high display quality, and such high display quality electro-optical. It is an object of the present invention to provide an electro-optical device driving method applied to the apparatus and a simple flicker inspection method.

  In order to solve the above problems, the electro-optical device according to the present invention includes a plurality of pixel units arranged in the image display region and a plurality of pixel units when displaying an image in the image display region. Inverts the polarity of the image signal with respect to the reference voltage every 1 / n screen display period divided by n (where n is a natural number of 2 or more). When the inspection is performed to invert the polarity of the image display area for each 1 / n screen display period and display an inspection image for inspecting the deviation amount from the optimum value of the reference voltage, And a drive unit that reverses the polarity of the image display area for each one-screen display period.

  According to the electro-optical device of the present invention, for example, an active matrix driving method is employed, and an image signal is supplied to each selected pixel unit column and an image is written during normal driving for displaying an image. The driving unit at this time performs polarity inversion driving at double speed. More specifically, each pixel unit is driven a plurality of times within one screen display period by the driving unit. That is, each pixel unit is driven at double speed or driven at n (where n is an integer of 2 or more). For example, an image signal for one field or one frame read into the buffer is read from the buffer at a double speed or n-times speed within a period of one field or one frame, and this one screen (for example, one field or one frame). Minute) image signal is repeatedly written n times in each pixel portion in a shorter cycle than one field or one frame. Each time an image signal for one screen is written once, the polarity of the image signal is inverted with respect to the reference voltage.

  Here, the “screen display period” is a period defined in advance as a display period occupied by one (that is, one type of) screen when displaying an image, and indicates a frame period or a field period, for example. The n-times speed driving is to write the same screen (inverting the polarity) every 1 / n period on the premise of this period. As a result, in one screen display period, “image for one screen” is written. "One type of image defined by the signal" is displayed.

  In this case, the polarity inversion frequency is, for example, 60 Hz which is twice as long as one frame period in double speed driving. That is, since the frequency of the luminance fluctuation (that is, flicker) accompanying polarity inversion is 60 Hz, the flicker cannot be visually recognized by human eyes. Therefore, when surface inversion driving is performed at double speed, display defects due to flicker can be substantially eliminated, and high-quality display is possible.

  Specifically, the reference voltage of the image signal in polarity inversion corresponds to the counter electrode potential. If the reference voltage value deviates from the optimum value, the image signal is relatively offset, which may cause problems such as liquid crystal burn-in. The adjustment of the reference voltage value performed to eliminate this is performed based on a work of visually inspecting the size of flicker, generally called flicker inspection. Flicker is a periodic luminance fluctuation that appears when the image signal value is generally asymmetric between positive polarity and negative polarity. That is, the setting error of the reference voltage value can be observed as flicker. Therefore, if flicker is used, it can be easily adjusted visually.

  However, in the double-speed drive type electro-optical device as in the present invention, flicker is hardly visually recognized during driving, and this adjustment method cannot be easily applied. Alternatively, for example, an inspection apparatus equipped with a CCD camera must be used as a substitute for human eyes.

  Therefore, in the electro-optical device of the present invention, when the image is displayed for displaying an image, the polarity inversion driving is performed at a double speed as described above, so that the flicker is not visually recognized and the display defect due to the generation of a horizontal electric field is suppressed. While the display with the high display quality is performed, at the time of flicker inspection, the polarity inversion period is driven to be lowered to one field period or one frame period. The frequency of polarity reversal at the time of inspection is, for example, 30 Hz, which is a level that is sufficiently visible. The driving method at the time of inspection can be realized by changing the driving method at the time of image display. For example, it can be easily realized only by changing the application timing of the drive control signal for driving the drive unit.

  Therefore, according to the electro-optical device of the present invention, it is possible to perform a simple flicker inspection visually without deteriorating high display quality.

  In one aspect of the electro-optical device according to the aspect of the invention, the driving unit effectively supplies only one of the n times of supply of the image signal corresponding to the one-screen display period at the time of the image display at the time of the inspection. .

  According to this aspect, the number of times of writing the image signal in the one-screen display period is n times when the double-speed image is displayed, but only once at the time of inspection.

  For example, when displaying an image, an image signal for one screen is stored in each of n memories and sequentially read, whereas at the time of inspection, the image signal is stored only in one memory, or the image signal Is read from only one of the stored memories, and the number of writings within one screen display period is restricted to one. Therefore, at the time of inspection, the driving frequency, that is, the polarity inversion frequency is pulled back to the original frequency of one screen display period (for example, 30 Hz which is the frame frequency), and visual inspection is possible.

  In another aspect of the electro-optical device according to the aspect of the invention, the driving unit supplies the image signal while thinning out during the inspection.

  According to this aspect, at the time of inspection, the image signal supplied at the time of double speed driving is thinned out (that is, the time interval in which the image signal is supplied is expanded by omitting a part of the image signal), thereby reducing the drive frequency, Thereby, the frequency of polarity inversion can be reduced. Note that the image signal omitted here may be set, for example, in units of pixels, or may be set in units of a predetermined number of lines.

  In another aspect of the electro-optical device according to the aspect of the invention, the driving unit may include a first partial region that is not adjacent to each other among a plurality of partial regions obtained by dividing the image display region by a dividing line along a horizontal scanning direction. And the second partial region adjacent to the first partial region are inverted with complementary polarities.

  According to this aspect, the first and second partial regions obtained by dividing the image display region in the horizontal scanning direction are subjected to polarity inversion driving so as to have opposite polarities. That is, the two groups of partial regions are driven to invert the surface with complementary polarities. The normal surface inversion drive is superior to the line inversion drive in that there is almost no influence of the transverse electric field, but as described above, the positive field (or positive frame) and the negative field (or negative electrode) In the case of the characteristic frame), the applied voltage with respect to the intermediate potential becomes more or less asymmetrical, and therefore flicker occurs in the field period (or frame period). Further, when focusing on a certain data line, assuming that the polarity inversion period is 1 frame 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 frame. Then, at the moment of moving to the next frame, the polarity of the image signal supplied to the data line is reversed. At this time, since the image display area is scanned from the top to the bottom, in the upper pixel portion of the image display area, the image signal supplied to the data line is maintained for most of the holding period after the image signal is written. The polarity is the same as the held signal potential. On the other hand, in the lower pixel portion, the image signal having the opposite polarity to the signal potential to be held is applied to the data line for most of the holding period after the image signal is written. As described above, if there is a difference in the influence of the data line potential on the pixel electrode between the upper side and the lower side of the image display area, the charge leaks from the pixel portion on one side of the image display area, and proper display is not performed. There is a fear. For example, the display brightness may be tilted up and down, or a black image may appear to have a shadow.

  On the other hand, in this aspect, by driving the image display area into a plurality of partial areas, the difference in the influence of the potential of the data line between the upper side and the lower side of the image display area is reduced, and the accumulated charge is reduced. Display noise due to leakage can be suppressed. Therefore, higher quality display is possible. Here, the “partial region” refers to a region composed of at least two lines or more (that is, a region including two or more scanning lines) so that the surface inversion driving is performed.

  In another aspect of the electro-optical device according to the aspect of the invention, the driving unit generates a driving control signal for driving the driving unit at a pulse application timing different from that at the time of the image display at the time of the inspection.

  According to this aspect, in the drive unit, the drive control signal is generated so that the pulse application timing is different between the image display time and the inspection time. The drive control signal for inspection can be easily generated in the drive unit by changing the pulse cycle of the drive control signal for image display, for example.

  In another aspect of the electro-optical device of the present invention, the drive unit receives a drive control signal for driving the drive unit from the outside at a pulse application timing different from that during the image display during the inspection.

  According to this aspect, the drive control signal is externally input to the drive unit at the time of pulse application different from that at the time of image display during inspection. Since the drive control signal for inspection is required separately from the original drive for image display, if it can be temporarily supplied from outside and driven, it is almost the same as usual. Can be configured.

  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, the above-described electro-optical device of the present invention is provided. Since this electro-optical device is equipped with the drive circuit for the electro-optical device of the present invention, high-quality display is possible and at the same time a narrow pitch can be achieved. Examples of the electronic apparatus include a projection display device, a television receiver, a mobile phone, an electronic notebook, a word processor, a viewfinder type or a monitor 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 other electronic devices.

  In order to solve the above-described problem, the inspection method of the present invention has a plurality of pixel units arranged in an image display region and a screen on the plurality of pixel units when displaying an image in the image display region. Inverts the polarity of the image signal with respect to the reference voltage every 1 / n screen display period divided by n (where n is a natural number of 2 or more). An inspection method for inspecting an amount of deviation from an optimum value of the reference voltage in an electro-optical device including a drive unit that reverses the polarity of the image display area every 1 / n screen display period. The driving unit is driven so as to invert the polarity of the image display area for each one-screen display period, and an inspection image display step for displaying an inspection image, and by visually observing the inspection image, Deviation amount And an inspection step to inspect.

  According to the inspection method of the present invention, first, in the inspection image display step, the electro-optical device to be inspected is driven as described above in the section of the electro-optical device of the present invention. That is, when the original image is displayed, the polarity inversion period, which is the 1 / n screen display period, is set to the one screen display period and is driven to display the inspection image. By extending the polarity reversal period, flicker that should not be visually recognized at the time of image display appears on the inspection image at a level where it can be sufficiently visually recognized. Therefore, in the next inspection step, the flicker occurrence state in the inspection image can be visually observed, and the deviation amount from the optimum value of the reference voltage can be easily inspected.

  Therefore, according to the inspection method of the present invention, simple flicker inspection by visual inspection is possible for an electro-optical device having high display quality.

  In one aspect of the inspection method of the present invention, in the inspection image display step, a drive control signal for driving the drive unit is input from the outside to the drive unit at a pulse application timing different from that during the image display.

  According to this aspect, for example, an inspection is performed by driving the electro-optical device by inputting a drive control signal from an inspection drive waveform output device or the like. Therefore, it is not necessary to place an inspection drive circuit on the electro-optical device side, and the drive waveform at the time of inspection can be changed relatively easily by changing the pulse application timing of the drive control signal. Is possible.

  In order to solve the above-described problem, an electro-optical device driving method according to the present invention includes a plurality of pixel units arranged in an image display region, and a driving unit that supplies an image signal to the plurality of pixel units. An electro-optical device driving method applied to an optical device, wherein the driving unit includes n (where n is a single screen display period defined as a period during which one screen is displayed on the plurality of pixel units). For each 1 / n screen display period divided by a natural number of 2 or more), the polarity of the image display area is displayed in the 1 / n screen display by supplying the image signal while inverting the polarity with respect to a reference voltage. Driving to invert every period, and driving the driving unit to invert the polarity of the image display area for each one-screen display period.

  According to the driving method for an electro-optical device of the present invention, high-quality images in which flicker is not visually recognized can be displayed by performing polarity inversion driving at double speed, and the polarity inversion period can be set to one field period or one frame period. By driving to pull down, an image in which flicker can be visually recognized can be intentionally displayed. Such a driving method is effective for visual flicker inspection, for example, and can be easily realized only by changing the drive control signal application timing, etc., between double speed driving and when the polarity inversion period is lowered.

  Therefore, according to the driving method for an electro-optical device of the present invention, it is possible to perform a simple flicker inspection visually on an electro-optical device with high display quality.

  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: Schematic 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 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 point with the counter electrode 21, which will be described later, and the input image signals S1, S2,..., Sn are applied to the pixel portion and held 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 system, and applies scanning signals G1, G2,..., Gm 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 driving unit 60 of the electro-optical device according to the present embodiment includes a controller 61, a memory 62, a DA converter 64, and the like in addition to the data line driving circuit 101 and the scanning line driving circuit 104 described above. ing. 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 write / read operation in the memory 62, and the DA converter 64 of the image signal DATA corresponding to the write data line 6a. Function to output to.

  The memory 62 temporarily stores the image signal DATA for half a screen (for example, 1/2 frame) input from the outside, and outputs the stored image signal DATA with a delay of 1/2 vertical scanning period. Used for

  The DA converter 64 functions to DA convert the image signal DATA read from the memory 62 or directly input from the outside via the controller 61 and output the data signal Sx to the data line driving circuit 101. To do. The data line driving circuit 101 applies the input data signal Sx to the corresponding data line 6a. The polarity inversion circuit 63 functions to invert the polarity of the data signal Sx with respect to the potential of the counter electrode 21 in accordance with the polarity control signal FRP.

  The scanning line driving circuit 104 can perform basic line-sequential horizontal scanning by inputting the clock signal CLY and the inverted clock signal CLY ′ from the controller 61. Further, here, although one drive circuit is used, two start pulses DY1 and DY2 are input simultaneously, and enable signals ENB1 and ENB2 for shifting the output timings of the scan signals are input. Therefore, 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.

  The data line driving circuit 101 can sequentially select the data line 6 a that supplies the data signal Sx by the input of the clock signal CLX and the inverted clock signal CLX ′ from the controller 61.

  However, as will be described later, the driving method of the electro-optical device according to the present embodiment is different between simply displaying an image and performing flicker inspection. Specifically, at the time of flicker inspection before product shipment, a driving method in which the driving method set for image display is slightly modified is adopted. Therefore, in the present embodiment, the controller 61 is configured to be able to switch the operation between the image display mode and the inspection mode in accordance with, for example, a mode control signal CS input from the outside. Although specifically described later, at the time of inspection, the controller 61 supplies the enable signals ENB1 and ENB2 and the polarity control signal FRP at application timings different from those at the time of image display. Thereby, the drive method in the drive unit 60 is changed, and the display can be switched between the image display mode and the inspection mode.

<1-2: Driving Method of Electro-Optical Device During Image Display>
Next, a basic driving method when performing normal image display with 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 scanning period.

  As shown in FIG. 5, in the present embodiment, the pixel portions of the two partial regions 201 and 202 obtained by dividing the image display region 10a vertically and equally are driven by surface inversion with mutually complementary polarities. Here, this inversion period is set to 1/2 frame. That is, the scanning line driving circuit 104 and the data line driving circuit 101 are driven at a double speed, and writing of the data signal Sx to the partial areas 201 and 202 is performed for two screens in one frame period. Specifically, one frame data is divided into first and second two frame data having different polarities, and these are overwritten while being shifted by a ½ vertical period. This can be done by using the memory 62. At this time, data signals Sx having different polarities are written in the partial area 201 and the partial area 202.

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

  In FIG. 7, the data line driving circuit 101 inverts the polarity of the data signal Sx every horizontal scan, and the scanning line driving circuit 104 has different polarities of the data signal Sx to be written in the partial area 201 and the partial area 202. The horizontal scanning is performed as described above. For example, in the first horizontal scanning period, the mth scanning line 3a is scanned by the scanning signal Gm, and the negative potential data signal Sx is written. In the second horizontal scanning period, the (m / 2 + 1) th scanning line 3a is scanned by the scanning signal Gm / 2 + 1, and the positive potential data signal Sx is written to the pixel portion that was in the negative potential in the first horizontal scanning period. In the third horizontal scanning 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 scanning periods. Thereafter, such a selective writing operation is repeated. Accordingly, when scanning of each of the partial areas 201 and 202 is completed, the positive polarity area and the negative polarity area on the image display area 10a are completely reversed, and rewriting for one screen is performed. According to this method, if the entire surface of the image display area 10a is scanned, the 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 attention is paid to a certain horizontal scanning period, for example, the pixel portion scanned by the scanning signals G3 to Gm / 2 + 2 becomes an area in which data of positive potential is written, and the scanning signals G1 to G1. The pixel area scanned from G2 and Gm / 2 + 3 to Gm is an area where negative potential data is written (hereinafter, simply referred to as a negative area). It becomes a state where it is divided into sex regions. 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, the electro-optical device according to the present embodiment performs “double speed region scanning inversion driving” in which the surface inversion driving is performed for each partial region at double speed in the image display mode. That is, a positive polarity region and a negative polarity region that are half the width of the image display region 10a are inverted in one vertical period, and surface inversion driving is performed on each of the partial regions 201 and 202. In one vertical period, an arbitrary pixel portion and an adjacent pixel portion have a reverse polarity potential only for 2 / m, but most of the remaining time (m−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 data line 6a side, the polarity of the data signal Sx is inverted for each horizontal scanning period corresponding to the partial area 201 and the partial area 202, so that when the data line 6a is driven by the conventional surface inversion method. There is no significant 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 depending on the location of the screen can be avoided.

  Furthermore, in this embodiment, since the polarity inversion frequency is 100 Hz or more, which is twice the frequency of the input image signal by the double speed driving, flicker that can be recognized by human vision can be reliably suppressed.

<1-3: Configuration of Driving Circuit and Driving Method>
Next, specific means for realizing such a driving method will be described with reference to FIGS. FIG. 9 illustrates a configuration example of the scanning line driving circuit 104, and FIG. 10 illustrates a timing chart in the image display mode in the scanning line driving circuit 104 illustrated in FIG.

  In FIG. 9, the scanning line driving circuit 104 includes a shift register 66 and m AND circuits 67 to which outputs of the shift register are input. The shift register 66 receives the clock signal CLY, the inverted clock signal CLY ′, and the start pulses DY1 and DY2 from the controller 61, and starts from the input positions corresponding to the scanning lines 3a of the start pulses DY1 and DY2. The output signals are sequentially output at a predetermined cycle corresponding to CLY. This output signal is output in the above horizontal scanning order (see FIG. 6 or FIG. 7).

  The AND circuit 67 is configured to generate the scanning signals G1,... Gm by taking the logical product of the output signal of the shift register 66 and the enable signal ENB1 or ENB2. Here, the enable signals ENB1 and ENB2 are input to the even-numbered AND circuit 67 and the odd-numbered AND circuit 67, respectively.

  Next, the operation of the scanning line driving circuit 104 will be described with reference to FIG.

  In FIG. 10, start pulses DY1 and DY2 are output every 1/2 vertical scanning period and are shifted in the shift register 66 by a clock signal CLY rising every horizontal scanning period. Therefore, two output signals from the shift register 66 are output at the same timing so that the partial areas 201 and 202 are simultaneously scanned horizontally.

  On the other hand, the enable signals ENB1 and ENB2 rise alternately in each application period of the output signal. The output signal from the shift register 66 has its pulse width limited by the enable signal ENB1 or ENB2 in the AND circuit 67, and at the same time the position on the time axis is defined, and is output to the scanning line 3a as the scanning signal Gx. Two signals are simultaneously output from the shift register 66. The operation periods of the AND circuit 67 to which they are input are shifted by different enable signals ENB1 and ENB2, and simultaneously output the scanning signal Gx. There is no.

  Therefore, the scanning signals G1 to Gm are output in the order of the scanning signals G1, Gm / 2 + 1, G2, Gm / 2 + 2,... As shown in the figure, and the horizontal scanning as described above is realized. Incidentally, since the output signal from the shift register 66 is output in accordance with the clock signal CLY, there is a certain limit to the increase in the frequency due to the limitation by the clock cycle. If the pulse width is limited by taking the logical product with the signal, it can be narrowed.

  On the other hand, the polarity control signal FRP is generated and output so that “1” and “0” are inverted every application period of each pulse of the scanning signal Gx in the image display mode (see FIG. 4). Therefore, image signals are supplied with complementary polarities to the partial area 201 scanned by the scanning signals G1, G2,... And the partial area 202 scanned by the scanning signals Gm / 2 + 1, Gm / 2 + 2,. In this manner, “double speed area scanning inversion driving” in the image display mode is realized.

<1-4: Flicker inspection and driving method during inspection>
Next, a driving method for performing flicker inspection with such an electro-optical device will be described with reference to FIGS. FIG. 11 shows a timing chart in the inspection mode in the scanning line driving circuit 104 shown in FIG.

  The drive method in the image display mode is a kind of polarity inversion drive, and the potential of the counter electrode 21 corresponds to the reference voltage of the data signal Sx at that time. If the reference voltage value deviates from the optimum value, a DC offset potential is relatively applied to the data signal Sx, which may cause problems such as burn-in of the liquid crystal layer 50. In order to eliminate this, the voltage value of the counter electrode 21 serving as the reference potential is adjusted before the electro-optical device is shipped. This adjustment is performed based on an operation of visually inspecting the size of flicker, which is generally called flicker inspection. Flicker is a periodic luminance fluctuation, and generally appears when the image signal value is strongly asymmetric between positive polarity and negative polarity. Therefore, the setting error of the reference voltage value can be observed as flicker. By utilizing this phenomenon, adjustment can be easily performed without taking the trouble of monitoring the signal voltage value.

  However, since flicker driving is performed in the image display mode, flicker is hardly visually recognized. For this reason, for visual inspection, for example, an inspection device including a CCD camera instead of human eyes is required. Therefore, in the present embodiment, as described below, a driving method is adopted in which the polarity reversal period is reduced to one frame period at the time of flicker inspection.

  Switching from the image display mode to the inspection mode is performed according to a mode control signal CS input from the outside of the apparatus, for example. Thereafter, the enable signals ENB1 and ENB2 and the polarity control signal FRP are supplied from the controller 61 at application timings different from those at the time of image display.

  In FIG. 11, the enable signals ENB1 and ENB2 in the inspection mode have a pulse width that is halved and a period of application timing is doubled. In this case, in the AND circuit 67, an output based solely on the start pulse DY1 is selectively output as the scanning signal Gx. Therefore, as shown in FIG. 12A, the partial area 201 is scanned in the first ½ frame period, and the partial area 202 is scanned in the subsequent ½ frame.

  Further, in the inspection mode, since the polarity control signal FRP is not inverted during one frame period, the inversion frequency in polarity inversion is halved. The inversion frequency at this time is, for example, 30 Hz, and is at a level that can be sufficiently visually recognized as luminance fluctuations (that is, flicker) of the same frequency.

  Therefore, when the operator visually observes the image display area 10a that is being driven, the size of the flicker is determined, and the potential of the counter electrode 21 that is used as a reference for polarity inversion is adjusted accordingly. That is, if the potential of the counter electrode 21 is the optimum value or the deviation amount from the optimum value is within the allowable range, the flicker is within a certain range, and if the deviation amount exceeds the allowable range, the flicker is larger. Become. By adjusting the deviation of the reference potential in this way, the burn-in of the liquid crystal layer 50 is prevented.

  As described above, according to the present embodiment, the display is performed by “double speed area scanning inversion driving” at the time of image display, while the polarity inversion period is extended by taking an irregular driving method at the time of flicker inspection. Therefore, while displaying the image without making the flicker visually visible, the inspection worker can visually adjust the deviation of the reference voltage by viewing the displayed image and confirming the occurrence of the flicker. That is, it is possible to adjust the deviation of the reference voltage very easily while maintaining the display quality brought about by the high frequency driving.

  Note that the same drive as in the above embodiment can be realized by supplying only one of the two start pulses DY while keeping the waveforms of the enable signals ENB1 and ENB2 in the image display mode.

<2: Modification>
Next, a modification of the above embodiment will be described with reference to FIGS. Here, FIGS. 12B and 12C and FIGS. 13A to 13C show a driving method according to a modification of the above embodiment. However, FIG. 12A shows the driving method in the embodiment as described above.

  FIG. 12 shows a case where “double speed region scanning inversion driving” is performed in the image display mode. In FIG. 12B, in the inspection mode, driving is performed such that writing to the pixel portion is performed only once out of two times in the image display mode in one frame period. In such a driving method, for example, the enable signals ENB1 and ENB2 for controlling the memory 62 are controlled so that the polarity control signal FRP is inverted in one frame period and is only activated once in two write operations. Alternatively, it can be realized by controlling the supply of the start pulses DY1 and DY2. Also in this case, the polarity inversion period is doubled, and flicker can be visually recognized.

  In FIG. 12C, in the inspection mode, although writing is performed at double speed, the polarity is inverted every frame period. That is, it is only necessary to change the polarity control signal FRP so as to be inverted at a cycle of one frame, and it is possible to change the flicker cycle to an extent that it can be visually recognized very easily.

  FIG. 13 shows a case where double-speed surface inversion driving is performed in the image display mode. FIG. 13A shows an example in which the embodiment is changed to surface inversion driving. That is, the horizontal scanning speed is halved so that only half of the image display area 10a can be written in the ½ frame period, and one vertical scanning is completed over one frame period. Also in this case, the polarity inversion period is doubled as in the embodiment, and flicker can be visually recognized.

  FIG. 13B shows an example in which the driving method of FIG. 12B is changed to surface inversion driving. FIG. 13C shows an example in which the driving method shown in FIG. Also in these cases, the polarity inversion period is doubled, and flicker can be visually recognized.

<3: Electronic equipment>
Next, a specific example of a projection type color display device will be described with reference to FIG. 14 as an electronic apparatus using the electro-optical device described in detail above as a light valve. FIG. 14 is a schematic cross-sectional view of the projection type color display device.

  In FIG. 14, a liquid crystal projector 1100, which is 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 having a drive circuit mounted on a TFT array substrate. It is configured as a projector used as the 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. The light is divided into B and led 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. In addition, an electronic device including the same and an inspection method involving such a change are also included in the technical scope of the present invention.

  For example, 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). It 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 various devices such as a liquid crystal device, an organic EL device, an electrophoretic device such as electronic paper, and a display device (Field Emission Display and Surface-Conduction Electron-Emitter Display) using an electron-emitting device. A display device may be mentioned.

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. It is a block diagram which shows the structure which concerns on the drive system of an electro-optical apparatus. It is a figure for demonstrating the drive method of an electro-optical apparatus. It is a figure for demonstrating the drive method of an electro-optical apparatus. It is a figure for demonstrating the drive method of an electro-optical apparatus. It is a figure for demonstrating the drive method of an electro-optical apparatus. FIG. 3 is a circuit diagram illustrating a specific configuration of a drive circuit of an electro-optical device. 6 is a timing chart illustrating a driving method in an image display mode of the electro-optical device. 6 is a timing chart illustrating a driving method in an inspection mode of the electro-optical device. It is a conceptual diagram for demonstrating the drive method which concerns on the modification of embodiment. It is a conceptual diagram for demonstrating the drive method which concerns on the modification of 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, 21 ... Counter electrode, 30 ... TFT, 400 ... Capacitive wiring, 50 ... Liquid crystal layer, 60 ... Drive unit, 61 ... Controller, 62 ... Memory 63 ... Polarity inversion circuit 64 ... DA converter 66 ... Shift register 67 ... AND circuit 70 ... Storage capacitor 101 ... Data line drive circuit 104 ... Scan line drive circuit 201, 202 ... Partial region CLY, CLX ... clock signal, DY1, DY2 ... start pulse, G1 to Gm ... scanning signal, FRP ... polarity control signal, ENB1, ENB2 ... enable signal, CS ... mode control signal.

Claims (10)

A plurality of pixel portions arranged in the image display area;
When displaying an image in the image display area, a one-screen display period defined in advance as a period during which one screen is displayed in the plurality of pixel portions is divided by n (where n is a natural number of 2 or more). The polarity of the image display area is inverted every 1 / n screen display period by supplying an image signal with its polarity inverted with respect to a reference voltage every 1 / n screen display period, and the reference voltage An electro-optical device comprising: a driving unit that reverses the polarity of the image display area for each one-screen display period at the time of inspection for displaying an inspection image for inspecting a deviation amount from the optimum value of .   2. The drive unit according to claim 1, wherein at the time of the inspection, only one of the n times of supply of the image signal corresponding to the one-screen display period at the time of the image display is effectively supplied. Electro-optic device.   The electro-optical device according to claim 1, wherein the driving unit supplies the image signal while thinning out during the inspection.   The drive unit includes a first partial region that is not adjacent to each other and a second that is adjacent to the first partial region among a plurality of partial regions obtained by dividing the image display region by a dividing line along a horizontal scanning direction. 4. The electro-optical device according to claim 1, wherein the partial regions are inverted with the polarities complementary to each other. 5.   5. The drive unit according to claim 1, wherein the drive unit generates a drive control signal for driving the drive unit at a pulse application timing different from that during the image display during the inspection. The electro-optical device described.   5. The drive unit according to claim 1, wherein a drive control signal for driving the drive unit is input from the outside at a pulse application timing different from that during the image display during the inspection. The electro-optical device according to one item.   An electronic apparatus comprising the electro-optical device according to claim 1. At the time of image display for displaying an image on the plurality of pixel portions arranged in the image display region and the image display region, a one-screen display period defined in advance as a period during which one screen is displayed on the plurality of pixel portions. By supplying an image signal while inverting the polarity with respect to a reference voltage every 1 / n screen display period divided by n (where n is a natural number of 2 or more), the polarity of the image display area is set to 1 An inspection method for inspecting a deviation amount from an optimum value of the reference voltage in an electro-optical device including a drive unit that is inverted every / n screen display period,
An inspection image display step of displaying the inspection image by driving the drive unit so as to invert the polarity of the image display region for each one-screen display period;
And an inspection step of inspecting the deviation amount by visually observing the inspection image.   9. The inspection method according to claim 8, wherein, in the inspection image display step, a drive control signal for driving the drive unit is externally input to the drive unit at a pulse application timing different from that during the image display. . An electro-optical device driving method applied to an electro-optical device including a plurality of pixel units arranged in an image display region and a driving unit that supplies image signals to the plurality of pixel units,
For each 1 / n screen display period, the drive unit is divided by n (where n is a natural number of 2 or more) a one-screen display period defined in advance as a period during which one screen is displayed on the plurality of pixel units. And driving the image signal so that the polarity of the image display area is inverted every 1 / n screen display period by supplying the image signal while inverting the polarity with respect to a reference voltage;
Driving the drive unit so as to invert the polarity of the image display area for each one-screen display period.

Images