JP2009186682A - Electro-optical device and electronic equipment - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an electro-optical device in which common potential is suitably adjusted. <P>SOLUTION: The electro-optical device (100) is provided with: a pixel part (70); a dummy pixel part (70d); writing means (101, 104) for performing positive polarity writing and negative polarity writing to the dummy pixel part; detection means (134, 135) for detecting each of positive polarity discharge time which is time required for discharge of electric charges accumulated in a dummy pixel electrode (9d) on which the positive polarity writing is performed and negative polarity discharge time which is time required for discharge of electric charges accumulated in the dummy pixel electrode on which the negative polarity writing is performed; and a correction means (137) for correcting the common potential so that the positive polarity discharge time equals to the negative polarity discharge time. <P>COPYRIGHT: (C)2009,JPO&INPIT

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 such an electro-optical device.

  An example of this type of electro-optical device is a liquid crystal device in which a liquid crystal, which is an example of an electro-optical material, is sandwiched between a pair of element substrates and a counter substrate. In the pixel region where a plurality of pixels are arranged on the element substrate, a pixel portion including a pixel electrode corresponding to the intersection of the scanning line and the data line is formed, so that the plurality of pixel portions are planar in a matrix shape. Arranged. Each pixel unit includes, for example, a thin film transistor (hereinafter referred to as “TFT” as appropriate) as a pixel switching element. When the electro-optical device is driven, when a pixel switching element is turned on by supplying a scanning signal from the scanning line in each pixel unit, an image signal is supplied from the data line to the pixel electrode via the pixel switching element. . Further, typically, a common electrode (or a counter electrode) is formed in a solid shape in common with the plurality of pixel portions in almost the entire pixel region corresponding to the plurality of pixel electrodes. When the liquid crystal device is driven, an applied voltage based on a potential difference between the pixel electrode and the common electrode is applied to the liquid crystal. As a result, the orientation and order of the liquid crystals are controlled, and image display is possible.

  In such a liquid crystal device, the polarity of the voltage applied to the liquid crystal is reversed at regular intervals (that is, polarity inversion driving is performed) in order to prevent liquid crystal burn-in. Specifically, with reference to a predetermined reference potential (typically, a common potential applied to the common electrode), the potential applied to the pixel electrode is alternated between the high potential side and the low potential side at regular intervals. It is changed and written. In other words, positive polarity writing and negative polarity writing are alternately performed at regular time intervals. In this case, the common potential may be fixed, or the common potential at the time of positive polarity writing may be changed to the low potential side, and the common potential at the time of negative polarity writing may be changed to the high potential side.

  The potential written to the pixel electrode in this manner is preferably held until the next writing, but in reality, the potential fluctuates due to the influence of the stray capacitance existing between the gate and the source of the TFT. End up. Such fluctuations in the potential of the pixel electrode cause a difference between the potential difference between the pixel electrode and the common electrode during positive polarity writing and the potential difference between the pixel electrode and the common electrode during negative polarity writing. It might be. As a result, an asymmetric potential with respect to the common potential may be applied to the liquid crystal between the positive polarity writing and the negative polarity writing. Further, even when the potential written to the pixel electrode is suitably held, the common potential varies (or when the common potential changes alternately on the high potential side and the low potential side, A similar problem occurs when the center potential of the common potential fluctuates). This is not preferable because it causes flickering of the screen and burn-in of the liquid crystal.

  Therefore, in order to solve such inconvenience, a technique for manually adjusting the common potential (see, for example, Patent Document 1), a potential difference between the pixel electrode and the common electrode at the time of positive polarity writing, By monitoring the potential difference between the pixel electrode and the common electrode during writing, the potential difference between the pixel electrode and the common electrode during positive polarity writing and the potential difference between the pixel electrode and the common electrode during negative polarity writing A technique for adjusting the common potential so as to be equal (for example, see Patent Document 2) has been developed.

JP-A-8-63128 Japanese Patent Laid-Open No. 2004-164777

  However, in the technique disclosed in Patent Document 1, it is necessary for the operator to manually adjust the common potential, and therefore it is necessary to perform it at the time of shipment. For this reason, there is a technical problem that it is impossible to cope with a case where a deviation of the write potential or the common potential occurs after shipment. Moreover, since the technique disclosed in Patent Document 2 directly measures a potential difference, the measurement accuracy is not always excellent, and as a result, the adjustment accuracy is not always excellent. Has technical problems.

  SUMMARY An advantage of some aspects of the invention is that it provides an electro-optical device that suitably adjusts a common potential and an electronic apparatus including such a driving device.

(Electro-optical device)
The electro-optical device according to the aspect of the invention includes the pixel unit arranged in the image display region, the dummy pixel unit arranged in the dummy pixel region located around the image display region, and the dummy pixel unit with respect to the dummy pixel unit. Positive writing in which the writing potential to the dummy pixel electrode included in the pixel portion is higher than the common potential supplied to the common electrode, and the writing potential to the dummy pixel electrode is lower than the common potential. A writing means for performing negative polarity writing on the potential side, a positive polarity discharge time which is a time required for discharging the charge accumulated in the dummy pixel electrode on which the positive polarity writing has been performed, and the negative polarity book Detecting means for detecting each of the negative discharge times, which is the time required for discharging the charge accumulated in the dummy pixel electrode, and the positive discharge time and the negative discharge time are made equal. And the common potential And a positive correcting means.

  According to the electro-optical device of the present invention, it is possible to perform image display or the like using pixel units (typically, a plurality of pixel units arranged in a matrix) arranged in the image display region. In the present invention, typically, positive polarity writing and negative polarity writing are alternately performed at predetermined time intervals. For example, the positive polarity writing is performed on the pixel portions in the same row arranged along the scanning line, and the negative polarity writing is performed on the pixel portions in adjacent rows. Here, the positive polarity writing is based on a predetermined reference potential (typically, the common potential of the common electrode that applies an electric field to the electro-optical material together with the pixel electrode included in the pixel portion). The state in which the potential of the image signal applied to the pixel electrode provided is on the high potential side is shown. On the other hand, negative-polarity writing is based on a predetermined reference potential (typically, a common potential of a common electrode that applies an electric field to an electro-optical material together with a pixel electrode included in the pixel portion). This shows a state where the potential of the image signal applied to the pixel electrode provided is on the low potential side. At this time, while fixing the common potential and changing only the potential of the image signal applied to the pixel electrode to the high potential side with respect to the common potential, positive writing is performed, and the image applied to the pixel electrode The negative polarity writing may be performed by changing only the signal potential to the low potential side with respect to the common potential. Alternatively, the positive potential writing is performed by changing the common potential to the low potential side and the potential of the image signal applied to the pixel electrode to the high potential side with respect to the common potential, and the common potential is set to the high potential side. The negative polarity writing may be performed by changing the potential of the image signal applied to the pixel electrode to a lower potential side with respect to the common potential. Such a writing operation may be performed by the operation of the writing means. As a result, the polarity of the voltage applied to the electro-optical material such as liquid crystal can be reversed every predetermined time, so that burn-in can be suitably prevented.

  In particular, the electro-optical device of the present invention includes a dummy pixel region in which a dummy pixel portion is disposed around an image display region used for image display. The dummy pixel portion is intended to indicate a pixel portion that does not necessarily need to be used for image display, and is preferably formed so that the configuration of the pixel portion is simulated and the operation thereof simulates the operation of the pixel portion.

  Positive polarity writing and negative polarity writing are performed on the dummy pixel portion in the dummy pixel region in the same manner as the writing operation on the pixel portion by the operation of the writing means. As a result of the writing operation, charges corresponding to the potential difference between the potential of the applied image signal and the common potential of the common electrode are accumulated in the dummy pixel electrode included in the dummy pixel portion. Thereafter, the discharge process of the charge accumulated in the dummy pixel electrode is performed at a predetermined timing. At this time, a positive discharge time, which is a time required for discharging the charge accumulated in the dummy pixel electrode on which the positive writing has been performed, is detected by the operation of the detection means. Similarly, the negative discharge time, which is the time required to discharge the charge accumulated in the dummy pixel electrode on which negative polarity writing has been performed, is detected.

  Here, if the positive polarity discharge time and the negative polarity discharge time are equal, the potential difference between the potential of the image signal when the positive polarity writing is performed and the common potential of the common electrode, and the negative polarity writing are performed. It is considered that the potential difference between the potential of the image signal at that time and the common potential of the common electrode is equal. That is, an image signal having a potential symmetric with respect to the common potential is applied to the dummy pixel electrode (or the pixel electrode included in the pixel portion) between the positive polarity writing and the negative polarity writing. Conceivable. For this reason, since there is little or no flicker, correction of the common potential by the correcting means (in other words, adjustment) is unnecessary.

  On the other hand, if the positive discharge time and the negative discharge time are not equal, the potential difference between the potential of the image signal and the common potential of the common electrode when the positive writing is performed, and the negative writing is performed. It is considered that the potential difference between the potential of the image signal and the common potential of the common electrode is not equal. That is, an image signal having an asymmetric potential with respect to the common potential is applied to the dummy pixel electrode (or the pixel electrode included in the pixel portion) between the positive polarity writing and the negative polarity writing. Conceivable. For this reason, since flicker can occur or has already occurred, the correction of the common potential is performed by the correcting means. Specifically, the positive discharge time and the negative discharge time are equalized (in other words, the potential difference between the potential of the image signal when the positive writing is performed and the common potential of the common electrode, The common potential is changed so that the common potential is changed to the high potential side or the low potential side so that the potential difference between the image signal potential and the common potential of the common electrode is equal when negative writing is performed. It is corrected. Thereafter, the writing operation to the pixel portion is performed using the corrected common potential.

  Therefore, according to the electro-optical device of the present invention, an image signal having an asymmetric potential with respect to the common potential is applied to the pixel electrode between the positive polarity writing and the negative polarity writing. Generation | occurrence | production can be suppressed suitably. Accordingly, it is possible to suppress the occurrence of flicker and the occurrence of seizure of the electro-optical material.

  Further, since the common potential is automatically corrected by the operations of the detection unit and the correction unit, it is not necessary to manually correct the common potential. Therefore, the accuracy of correcting the common potential can be improved, and the common potential can be corrected even after the electro-optical device is shipped.

  Further, instead of directly detecting a voltage that is relatively difficult to detect on an electro-optical device such as a liquid crystal device (or relatively difficult to detect because it is difficult to newly install a device for detecting a voltage). Since the amount of charge that is relatively easy to detect and the time required for the discharge are detected, the advantage that the detection operation is relatively easy can be enjoyed. Furthermore, since the detection accuracy can be improved as compared with a mode of directly detecting the potential difference, as a result, the correction accuracy of the common potential can be improved.

  In addition, since the writing operation and the detection operation are performed on the dummy pixel portion, the above-described operation can be performed without affecting the normal image display operation using the pixel portion.

  In one aspect of the electro-optical device according to the aspect of the invention, the detection unit counts the number of pulses of a clock pulse that rises at a predetermined period, and a comparator that compares the amount of charge accumulated in the dummy pixel electrode with a predetermined value. A counter is provided, and when the amount of charge accumulated in the dummy pixel electrode falls below the predetermined value after the discharge of the charge accumulated in the dummy pixel electrode for which the positive address has been performed is started, Until it is determined by the comparator, the number of clock pulses counted by the counter is detected as the positive discharge time, and the charge accumulated in the dummy pixel electrode on which the negative write has been performed. When the amount of electric charge accumulated in the dummy pixel electrode falls below the predetermined value after the start of discharge, the comparator determines. Until the, the number of pulses counted the clock pulses by the counter, is detected as the negative polarity discharge time.

  According to this aspect, it is possible to easily and reliably detect the amount of charge accumulated in the dummy pixel electrode and the time required for discharging the accumulated charge. As a result, since the above-described common potential can be corrected appropriately, the above-described effects can be suitably enjoyed.

  In another aspect of the electro-optical device according to the aspect of the invention, the detection unit further includes a discharge constant current source for discharging the charge accumulated in the dummy pixel electrode.

  According to this aspect, the charge accumulated in the dummy pixel electrode can be suitably discharged. In particular, the time required for discharge can be finely adjusted by adjusting the parameters (for example, current value, voltage value, etc.) of the constant current source for discharge. Accordingly, it is possible to detect each of the positive discharge time and the negative discharge time in a mode that is easier to detect or in a flexible mode that matches the specifications of various components included in the electro-optical device or the electro-optical device.

  In another aspect of the electro-optical device according to the aspect of the invention, a plurality of the pixel portions are arranged in a matrix corresponding to the intersection of the scanning lines and the data lines, and a plurality of the dummy pixel portions are arranged along the scanning lines. ing.

  According to this aspect, it is possible to accumulate a relatively large amount of charges as the entire plurality of dummy pixel portions. Therefore, the accuracy of detection of the positive discharge time and the negative discharge time can be relatively improved.

  In another aspect of the electro-optical device of the present invention, a light shielding film is formed in the dummy pixel portion.

  According to this aspect, even if a plurality of dummy pixel portions are provided, the normal display operation using the pixel portions is not affected.

  In another aspect of the electro-optical device of the present invention, the dummy pixel region is provided adjacent to at least one of both ends of the image display region.

  According to this aspect, the dummy pixel area is arranged on the upper side and / or lower side of the image display area with reference to the scanning direction in the vertical direction. That is, the image display area is not divided into a plurality of areas by the dummy pixel area. For this reason, the above-described operation can be performed without affecting the normal image display operation using the pixel portion.

  In another aspect of the electro-optical device according to the aspect of the invention, the writing unit performs the positive writing and the negative writing using a writing potential corresponding to the maximum gradation.

  According to this aspect, a relatively large amount of charge can be stored in the dummy pixel portion. Therefore, the accuracy of detection of the positive discharge time and the negative discharge time can be relatively improved.

  Note that the writing potential corresponding to the maximum gradation means the potential of an image signal that maximizes the potential difference from the common potential, and is typically an image that can be applied to the pixel electrode. Indicates the maximum and minimum potentials of the signal.

  In another aspect of the electro-optical device according to the aspect of the invention, the correcting unit may change the common potential to a relatively high potential side when the positive discharge time is longer than the negative discharge time. A common potential is corrected, and when the negative discharge time is longer than the positive discharge time, the common potential is corrected so as to change the common potential to a relatively low potential side.

  According to this aspect, for example, if the positive discharge time is longer than the negative discharge time, the potential difference between the potential of the image signal and the common potential of the common electrode when the positive writing is performed is negative. It is considered that the potential difference between the potential of the image signal when writing is performed and the common potential of the common electrode is larger. For this reason, the potential difference between the two can be made equal by shifting the common potential to the relatively high potential side. Alternatively, if the positive polarity discharge time is longer than the negative polarity discharge time, the potential difference between the potential of the image signal when the positive polarity writing is performed and the common potential of the common electrode is when the negative polarity writing is performed. This is considered to be larger than the potential difference between the potential of the image signal and the common potential of the common electrode. For this reason, the potential difference between the two can be made equal by shifting the common potential to the relatively high potential side. Therefore, the above-described effects can be suitably enjoyed.

  In another aspect of the electro-optical device according to the aspect of the invention, the detection unit may start discharging the charge accumulated in the dummy pixel electrode after a predetermined period has elapsed since the positive writing is performed. The positive discharge time is detected, and the discharge of the charge accumulated in the dummy pixel electrode is started after a lapse of a predetermined period after the negative write is performed, and then the negative discharge time is detected. To do.

  In general, the state of the pixel portion is unstable immediately after the image signal is written to the pixel portion. Specifically, for example, the electric field applied to the electro-optical device may fluctuate. On the other hand, after a certain amount of time has elapsed since the writing operation, the state of the pixel portion is relatively stable. Therefore, according to this aspect, since the time is detected after the state of the dummy pixel portion is stabilized, it is possible to relatively improve the accuracy of detection of the positive discharge time and the negative discharge time.

  As described above, in the aspect of the electro-optical device that detects the positive discharge time or the negative discharge time after a predetermined period has elapsed since the positive writing or the negative writing has been performed, the predetermined period is one vertical scan. You may comprise so that it may be a period (for example, 1 frame period, 1 field period, etc.).

  With this configuration, the writing to the dummy pixel unit described above is performed at a timing that considers scanning in a normal image display operation using the pixel unit or at the same timing as scanning in a normal image display operation using the pixel unit. And the detection operation of the positive polarity discharge time and the negative polarity discharge time can be performed. Accordingly, the detection accuracy of the positive discharge time and the negative discharge time can be relatively improved as described above without affecting the normal image display operation using the pixel portion.

  In another aspect of the electro-optical device according to the aspect of the invention, the writing unit performs the positive polarity writing or the negative polarity writing only for one horizontal scanning period, and the detection unit detects the positive polarity discharge time or The negative discharge time is detected for only one horizontal period.

  According to this aspect, the writing to the dummy pixel unit described above is performed at a timing that considers scanning in the normal image display operation using the pixel unit or at the same timing as scanning in the normal image display operation using the pixel unit. The operation and the detection operation of the positive discharge time and the negative discharge time can be performed. Accordingly, the detection accuracy of the positive discharge time and the negative discharge time can be relatively improved as described above without affecting the normal image display operation using the pixel portion. This is a particularly remarkable effect in the aspect of detecting the positive discharge time or the negative discharge time after a predetermined period (for example, one vertical scanning period) has elapsed since the positive writing or the negative writing was performed. It is.

  In another aspect of the electro-optical device according to the aspect of the invention, the writing unit may perform the positive writing or the negative writing on the dummy pixel portion before or after writing to the pixel portion. And the detecting means detects the positive discharge time or the negative discharge time before or after writing to the pixel portion.

  According to this aspect, the writing operation to the dummy pixel portion and the detection operation of the positive discharge time and the negative discharge time affect the image display operation using the pixel portion (particularly, the display operation in one vertical scanning period). Never give. That is, the writing operation to the dummy pixel portion and the detection operation of the positive discharge time and the negative discharge time are not performed during the image display operation using the pixel portion. For this reason, the above-described operation can be performed without affecting the normal image display operation using the pixel portion.

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

  According to the electronic apparatus of the present invention, since the electro-optical device (or various aspects thereof) of the present invention described above is provided, the same effects as those received by the electro-optical device of the present invention described above can be obtained. Can do. In other words, the projection display device, television, mobile phone, electronic notebook, portable audio player, word processor, digital camera, viewfinder type that can enjoy the same effects as those obtained by the electro-optical device of the present invention described above. Alternatively, various electronic devices such as a monitor direct-view video recorder, a workstation, a videophone, a POS terminal, and a touch panel can be realized.

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

  The best mode for carrying out the present invention will be described below with reference to the drawings. In the following description, a liquid crystal device is used as an example of the electro-optical device according to the invention.

(1) Basic Configuration of Liquid Crystal Device First, the configuration of the liquid crystal device according to the present embodiment will be described with reference to FIGS. 1 and 2. FIG. 1 is a plan view showing the configuration of the liquid crystal device according to this embodiment, and FIG. 2 is a cross-sectional view taken along the line HH ′ of FIG.

  1 and 2, in the liquid crystal device 100 according to the present embodiment, the TFT array substrate 10 and the counter substrate 20 are arranged to face each other. A liquid crystal layer 50 is sealed between the TFT array substrate 10 and the counter substrate 20, and the TFT array substrate 10 and the counter substrate 20 are in a frame-shaped or frame-shaped seal region located around the image display region 10a. The sealing material 52 provided is bonded to each other.

  In FIG. 1, a light-shielding frame light-shielding film 53 that defines the frame area of the image display region 10a is provided on the counter substrate 20 side in parallel with the inside of the seal region where the sealing material 52 is disposed. In the peripheral region, the data line driving circuit 101, the driver IC circuit 130, and the external circuit connection terminal 102 are provided along one side of the TFT array substrate 10 in a region located outside the sealing region where the sealing material 52 is disposed. It has been. However, the data line driving circuit 101 may be provided inside the seal region so that the data line driving circuit 101 is covered with the frame light shielding film 53. The sampling circuit 7 is provided so as to be covered with the frame light shielding film 53 on the inner side of the seal region along the one side. Further, the scanning line driving circuit 104 is provided so as to be covered with the frame light-shielding film 53 inside the seal region along two sides adjacent to the one side. Further, on the TFT array substrate 10, vertical conduction terminals 106 for connecting the two substrates with a vertical conduction material 107 are disposed in regions facing the four corner portions of the counter substrate 20. Thus, electrical conduction can be established between the TFT array substrate 10 and the counter substrate 20.

  On the TFT array substrate 10, a lead wire 90 for electrically connecting the external circuit connection terminal 102 and the data line driving circuit 101, the driver IC circuit 130, the scanning line driving circuit 104, the vertical conduction terminal 106, and the like. Is formed.

  In FIG. 2, on the TFT array substrate 10, there is formed a laminated structure in which pixel switching TFTs (Thin Film Transistors), which are driving elements, and wirings such as scanning lines and data lines are formed. In the image display area 10a, pixel electrodes 9a are provided in a matrix on the upper layer of wiring such as pixel switching TFTs, scanning lines, and data lines. An alignment film 8 is formed on the pixel electrode 9a. On the other hand, a light shielding film 23 is formed on the surface of the counter substrate 20 facing the TFT array substrate 10. The light shielding film 23 is formed of, for example, a light shielding metal film or the like, and is patterned, for example, in a lattice shape in the image display region 10a on the counter substrate 20. On the light shielding film 23, a common electrode 21 made of a transparent material such as ITO is formed in a solid shape so as to face the plurality of pixel electrodes 9a. An alignment film 8 is formed on the common electrode 21. 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. The above configuration is a so-called vertical electric field mode configuration in which the liquid crystal layer 50 is driven by an electric field between the pixel electrode 9a of the TFT array substrate 10 and the common electrode 21 of the counter substrate 20, but IPS (In-Plane Switching), A lateral electric field mode configuration such as FFS (fringe field switching) may be used. In the horizontal electric field mode, since the pixel electrode and the common electrode are arranged on the TFT array substrate side, there is no electrode on the counter substrate, so that there is no need for a vertical conduction terminal for connecting the TFT array substrate and the counter substrate.

  In addition, a dummy pixel region 10d is arranged in the frame region that can be covered with the frame light shielding film 53 around the image display region 10a on the TFT array substrate 10 as described later. In the present embodiment, in the dummy pixel region 10d, a dummy pixel portion 70d is formed by simulating the pixel portion 70, and a dummy pixel electrode 9d is disposed for each dummy pixel portion 70d. The dummy pixel portion 70 d may be covered with the frame light shielding film 53.

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

  In the above configuration, the driver IC circuit 130 is formed on the liquid crystal device 100. However, the driver IC circuit 110 may be formed on an FPC (Flexible Print Circuit). Alternatively, it may be configured to be formed on an external circuit electrically connected to the liquid crystal device 100 via the external circuit connection terminal 102.

(2) Detailed Configuration of Liquid Crystal Device Next, with reference to FIGS. 3 and 4, an electrical configuration of a main part of the liquid crystal device 100 according to the present embodiment will be described. FIG. 3 is a block diagram conceptually showing an electrical configuration of a main part of the liquid crystal device 100 according to the present embodiment. FIG. 4 is a diagram illustrating a write operation by the liquid crystal device 100 according to the present embodiment. It is a graph which shows each of the potential of the applied image signal, and a common potential.

  In FIG. 3, the liquid crystal device 100 according to the present embodiment includes a scanning line driving circuit 104, a data line driving circuit 101, and a driver IC circuit 130 in a peripheral region located around the image display region 10 a on the TFT array substrate 10. Etc. are formed.

  The scanning line driving circuit 104 sequentially supplies scanning signals to the scanning lines Y1 to Yn (where n is an integer of 1 or more). For example, when a high level scanning signal is supplied to a certain scanning line Ya (where a is an integer satisfying 1 ≦ a ≦ n), all TFTs 116 connected to the scanning line Ya are turned on, and this scanning is performed. All the pixel portions 70 corresponding to the line Ya are selected.

  The data line driving circuit 101 sequentially supplies an image signal to the data lines X1 to Xm (where m is an integer equal to or greater than 1), and a write voltage based on the image signal is supplied to the pixel electrode 9a via the TFT 116 in the on state. Write to.

  The liquid crystal device 100 according to the present embodiment is further provided with a plurality of pixel units 70 arranged in a matrix in the image display region 10 a occupying the center of the TFT array substrate 10.

  The pixel unit 70 includes a pixel switching TFT 116, a pixel electrode 9 a, a liquid crystal element 118, a common electrode 21, and a storage capacitor 119.

  The TFT 116 has a source terminal electrically connected to one of the data lines X1 to Xm, a gate terminal electrically connected to one of the scanning lines Y1 to Yn, and a drain terminal electrically connected to the pixel electrode 9a. Has been. The pixel switching TFT 116 is switched between an on state and an off state by a scanning signal supplied from the scanning line driving circuit 104.

  The liquid crystal element 118 includes a pixel electrode 9 a, a common electrode 21, and a liquid crystal positioned between the pixel electrode 9 a and the common electrode 21. The pixel electrode 9a is electrically connected to one of the data lines X1 to Xm through the TFT 116. The common electrode 21 is electrically connected to the common wiring COM. The pixel electrode 9a and the common electrode 21 are both provided on the TFT array substrate 10 as described above. During the operation of the liquid crystal device 100, the pixel electrode 9a having the potential (writing potential) of the image signal supplied from the data lines X1 to Xm and the TFT 116 and the common potential having the common potential supplied via the common wiring COM. An electric field is generated between the electrodes 21. The liquid crystal is driven according to the electric field, that is, the orientation or order of the molecular assembly is changed according to the electric field, thereby modulating light and enabling gradation display.

  The storage capacitor 119 is added in parallel with the liquid crystal element 118 in order to prevent the held image signal from leaking. One electrode constituting the storage capacitor 119 is electrically connected to the pixel electrode 9 a, and the other electrode is electrically connected to the common electrode 21.

  The above liquid crystal device 100 operates as follows.

  First, by supplying a high level scanning signal from the scanning line driving circuit 104 to the scanning line Ya, all the TFTs 116 connected to the scanning line Ya are turned on, and all the pixel units 70 related to the scanning line Ya are turned on. select.

  Further, in synchronization with the selection of the pixel unit 70 related to the scanning line Ya, a positive image signal and a negative image signal are transferred from the data line driving circuit 101 to the data lines X1 to Xm according to the potential of the common wiring line COM. Are alternately supplied every horizontal scanning period. Specifically, as shown on the left side of FIG. 4, if the common potential of the common wiring COM is VCOML on the relatively low potential side, an image signal having a positive writing potential with respect to the common potential is stored as data. Supply from line X1 to Xm. Such a writing operation is hereinafter referred to as positive polarity writing. On the other hand, as shown on the right side of FIG. 4, if the common potential of the common wiring COM is VCOMH on the relatively high potential side, an image signal having a negative write potential with respect to the common potential is transmitted from the data lines X1 to Xm. To supply. Such a writing operation is hereinafter referred to as negative polarity writing.

  In particular, in this embodiment, positive polarity writing and negative polarity writing to each row are alternately performed every predetermined period (typically, one vertical scanning period (that is, one frame period or one field period)). Done. Specifically, for example, when positive writing is performed on the pixel unit 70 corresponding to the scanning line Ya in one vertical scanning period, it corresponds to the scanning line Ya in the next vertical scanning period. Negative polarity writing is performed on the pixel unit 70. On the other hand, when negative writing is performed on the pixel portion 70 corresponding to the scanning line Ya in one vertical scanning period, the positive polarity is applied to the pixel portion 70 corresponding to the scanning line Ya in the next one vertical scanning period. Sexual writing is performed. Further, writing with different polarities is performed on the pixel portion 70 corresponding to the scanning line Ya-1 and the pixel portion 70 corresponding to the scanning line Ya. That is, when the positive writing is performed on the pixel unit 70 corresponding to the scanning line Ya-1, the negative writing is performed on the pixel unit 70 corresponding to the scanning line Ya. On the other hand, when negative writing is performed on the pixel unit 70 corresponding to the scanning line Ya-1, positive writing is performed on the pixel unit 70 corresponding to the scanning line Ya.

  As a result, an image signal is supplied from the data line driving circuit 101 to the pixel units 70 selected by the scanning line driving circuit 104 via the data lines X1 to Xm and the TFT 116, and a writing voltage based on the image signal is set. Data is written to the pixel electrode 9a. As a result, a potential difference is generated between the pixel electrode 9a and the common electrode 21, and a driving voltage is applied to the liquid crystal.

  In the present embodiment, in addition to such image display using the pixel unit 70 provided in the image display region 10, a common potential adjustment operation using the dummy pixel unit 70d provided in the dummy pixel region 10d (in other words, paraphrase) Corrective operation). The configuration for performing this adjustment operation will be described in detail below.

(3) Configuration for Adjusting Common Potential As shown in FIG. 3, in a dummy pixel region 10d provided around the image display region 10a (particularly, below the image display region 10a in FIG. 3). Is provided with a dummy pixel portion 70d. More specifically, a plurality of dummy pixel portions 70d are provided along one dummy scanning line Yd provided subsequent to the scanning lines Y1 to Yn in the dummy pixel region 10d. Here, the same number of dummy pixel portions 70d as the number of data lines X1 to Xm are provided. Further, dummy scanning lines Yd, data lines X1 to Xm, and common wiring lines COM are continuously wired in the same pattern from the image display area 10a to the dummy pixel area 10d. The pixel unit 70 and the dummy pixel unit 70d have the same configuration. Specifically, the dummy pixel portion 70d includes a dummy pixel electrode 9a, a dummy TFT 116d, and a dummy storage capacitor 119d. Accordingly, the positive polarity writing and the negative polarity writing can be performed on the dummy pixel portion 70d as well as the pixel portion 70.

  Further, as shown in FIG. 3, in the dummy pixel region 10d, the timing for detecting the charge accumulated in the dummy pixel electrode 9d is further defined by performing positive polarity writing or negative polarity writing. A detection timing signal line A to which a detection timing signal is supplied and a discharge line D serving as a path through which the charge accumulated in the dummy pixel electrode 9d is discharged are formed. The detection timing signal line A and the discharge line D preferably extend in the horizontal direction, like the scanning lines Y1 to Yn and the dummy scanning line Yd.

  The detection timing signal line A is electrically connected to the gate terminals of the plurality of discharge switching TFTs 121d provided so as to correspond to the plurality of dummy pixel portions 70d in the dummy pixel region 10d. The source terminals of the plurality of discharge switching TFTs 121d are electrically connected to the dummy pixel electrode 9d of the corresponding dummy pixel portion 70d among the plurality of dummy pixel portions 70d. The drain terminals of the plurality of discharge switching TFTs 121d are electrically connected to the discharge line D.

  As shown in the lower part of FIG. 3, the driver IC circuit 130 includes a switch SW1, two switches SW2, a discharge constant current source 132, a DC voltage source 133, a comparator 134, a counter 135, and a comparator 136. And a common potential supply circuit 137. In FIG. 3, a parasitic capacitance 131 between the common line CCOM and the discharge line D is also illustrated.

  In the driver IC circuit 130, the common wiring COM and the discharge line D are electrically connected. The common wiring COM is electrically connected to the common potential supply circuit 137. The common line COM is electrically connected to one end (the right end in FIG. 3) of the switch SW1, and the discharge line D is connected to the other end (the left end in FIG. 3) of the switch SW1. Electrically connected to the end). Further, a discharging constant current source 132 is electrically connected in parallel with the switch SW1. That is, one end of the switch SW1 and each of the common wiring lines COM are electrically connected to one end (the right end in FIG. 3) of the discharge constant current source 132, and the switch SW1. And the other end of the discharge constant current source 132 (the left end in FIG. 3) are electrically connected to each other.

  The circuit system including the discharge line D and the common wiring COM and the circuit system including the discharge constant current source 132 (further, the DC voltage source 133, the comparator 134, the counter 135, and the comparator 136) are switched by the switch SW2. It can be electrically connected or disconnected. Therefore, the charge accumulated in the dummy pixel electrode 9d is discharged through the discharge line D only when the switch SW2 is closed and the constant current is supplied from the discharge constant current source 132.

  One end of the constant current source for discharge 132 is electrically connected to one end of the DC voltage source 133 (the lower end in FIG. 3). The other end (upper end in FIG. 3) of the DC voltage source 133 is electrically connected to one input terminal of the comparator 134. The other end of the discharging constant current source 132 is electrically connected to the other input terminal of the comparator 134. Therefore, in the comparator 134, the amount of charge accumulated in the dummy pixel electrode 9d (in other words, the amount of charge in the discharge line D from which the charge accumulated in the dummy pixel electrode 9d is discharged) and the output ( That is, a comparison with the threshold voltage is performed.

  The output of the comparator 134 is input to a counter 135 to which a predetermined clock is periodically input. The counter 135 counts the number of clocks input from when the comparison operation in the comparator 134 is started until the output is inverted. That is, the electric charge accumulated in the dummy pixel electrode 9d is input to the counter 135 after the discharge of the electric charge accumulated in the discharge pixel D falls below the threshold voltage that is the output of the DC voltage source 133. The number of clocks is counted.

  The output of the counter 135 (that is, the number of clocks counted) is output to the comparator 136. The comparator 136 compares the output of the counter 135 when positive writing is performed on the dummy pixel electrode 9d and the output of the counter 135 when negative writing is performed on the dummy pixel electrode 9d. The comparison result is output to the common potential supply circuit 137.

  The common potential supply circuit 137 adjusts the common potential (that is, VCOMH and VCOML) based on the comparison result output from the comparator 136 and supplies the common potential to the common line COM.

(4) Common Potential Adjustment Operation Next, a specific example of the common potential adjustment operation will be described with reference to FIGS. FIG. 5 is a timing chart showing the operation of the liquid crystal device 100 when the positive polarity writing is performed on the dummy pixel electrode 9d, and FIG. 6 is the case where the negative polarity writing is performed on the dummy pixel electrode 9d. FIG. 7 and FIG. 8 are graphs conceptually showing the common potential adjusting operation, respectively.

  As shown in FIG. 5, the image signal is written to the pixel unit 70 in a certain vertical scanning period # 1-1. That is, by supplying high-level scanning signals in order to the scanning lines Y1 to Yn, image signals are written to all the pixel units 70 corresponding to the scanning lines Y1 to Yn. In the example shown in FIG. 5, positive writing is performed on the pixel unit 70 corresponding to the scanning line Y1, negative writing is performed on the pixel unit 70 corresponding to the scanning line Y2, and the scanning line Yn is performed. An example is shown in which negative polarity writing is performed on the pixel unit 70 corresponding to.

  After the high level scanning signal is supplied to the scanning line Yn, the high level scanning signal is supplied to the dummy scanning line Yd, and the image signal is supplied to the data lines X1 to Xm. The image signal supplied at this time is preferably an image signal having a writing potential corresponding to the maximum gradation. As a result, similarly to the pixel unit 70, image signal writing (particularly positive polarity writing) to the dummy pixel unit 70 is performed for one horizontal scanning period.

  Thereafter, after the vertical blanking period elapses, the image signal is written to the pixel unit 70 in the next vertical scanning period # 1-2. Here, negative writing is performed on the pixel portion 70 corresponding to the scanning line Y1, positive polarity writing is performed on the pixel portion 70 corresponding to the scanning line Y2, and pixels corresponding to the scanning line Yn. Positive writing is performed on the unit 70.

  After the high level scanning signal is supplied to the scanning line Yn, the positive polarity writing is performed in the previous vertical scanning period # 1-1, whereby the discharge process of the charge accumulated in the dummy pixel electrode 9d is performed. Done. Specifically, as shown in the lower part of FIG. 5, first, the switch SW2 that is normally in an off state (that is, an open state) is switched to an on state (that is, a closed state). As a result, the circuit system including the discharge line D and the circuit system including the discharge constant current source 132 (that is, the circuit system performing the discharge process) are electrically connected.

  Thereafter, the switch SW1 that is normally in the off state (that is, the open state) is switched to the on state (that is, the closed state) for a certain period of time. After a predetermined time has elapsed, the switch SW1 is switched to the off state again. As a result, the charge remaining in the discharge line D is discharged. Therefore, the discharge process can be performed on the charge accumulated in the dummy pixel electrode 9d by the most recent writing operation without being affected by the charge remaining in the discharge line D before the discharge process is started.

  Thereafter, a high-level detection timing signal is supplied to the detection timing signal line A. As a result, the switching TFT 121d included in each of the plurality of dummy pixel portions 70d is turned on, and the charge accumulated in each dummy pixel electrode 9d of the plurality of dummy pixel portions 70d is discharged through the discharge line D. As a result, the potential of the discharge line D rises according to the accumulated charge amount.

  Thereafter, supply of a constant current from the discharge constant current source 132 is started. Thereby, the discharge process of the electric charge discharged to the discharge line D is started. At this time, the counter 135 resets the count to zero before the constant current supply is started, and starts counting the clock simultaneously with the start of the constant current supply.

  Thereafter, the amount of charge remaining in the discharge line D is gradually reduced by the discharge process. At this time, the operation of the comparator 134 compares the remaining charge amount in the discharge line D with the threshold voltage that is the output of the DC voltage source 133. The counting in the counter 135 ends when the remaining charge amount in the discharge line D falls below the threshold voltage that is the output of the DC voltage source 133. In the example shown in FIG. 5, when the clock is counted up to “12”, the remaining charge amount in the discharge line D falls below the threshold voltage that is the output of the DC voltage source 133. The count has ended.

  Thereafter, the supply of the constant current from the discharge constant current source 132 is terminated, the supply of the high-level detection timing signal to the detection timing signal line A is terminated, and the switch SW2 is turned off, whereby the dummy pixel electrode The discharge process for the electric charge accumulated in 9d is completed. The above discharge process is typically performed during one horizontal scanning period, but of course, it may be performed for a period shorter or longer than one horizontal scanning period.

  The above shows an example of the operation when the positive polarity writing is performed on the dummy pixel electrode 9d. However, as shown in FIG. 6, the negative polarity writing is performed on the dummy pixel electrode 9d. In some cases, the same operation is performed. Specifically, for example, after the positive polarity writing and discharging processes are performed on the dummy pixel electrode 9d in two consecutive vertical scanning periods, the negative electrode on the dummy pixel electrode 9d in another two consecutive vertical scanning periods. Sexual writing and discharge processing are performed. As a result, the comparator 136 discharges the output of the counter 135 when positive writing is performed on the dummy pixel electrode 9d (that is, the charge accumulated in the dummy pixel electrode 9d subjected to positive writing is discharged. Time required for the negative polarity writing) and the output of the counter 135 when the negative polarity writing is performed on the dummy pixel electrode 9d (that is, the charge accumulated in the dummy pixel electrode 9d on which the negative polarity writing is performed) The time required to be discharged) is input.

  The comparator 136 compares the output of the counter 135 when positive writing is performed on the dummy pixel electrode 9d and the output of the counter 135 when negative writing is performed on the dummy pixel electrode 9d. Is called. Specifically, the magnitude relationship between the output of the counter 135 when positive polarity writing is performed on the dummy pixel electrode 9d and the output of the counter 135 when negative polarity writing is performed on the dummy pixel electrode 9d; The amount of difference between them is detected. The magnitude relationship and the difference amount are output to the common potential supply circuit 137.

  In the supply potential supply circuit 137, the common potential adjustment operation is performed according to the comparison result in the comparator 136.

  Specifically, first, the output of the counter 135 when the positive polarity writing is performed on the dummy pixel electrode 9d is equal to the output of the counter 135 when the negative polarity writing is performed on the dummy pixel electrode 9d. For example, the potential difference (specifically, V1 in FIG. 4) between the potential of the image signal (that is, the writing potential) and the common potential of the common electrode 21 when the positive polarity writing is performed, and the negative polarity writing. It is considered that the potential difference (specifically, V2 in FIG. 4) between the potential of the image signal and the common potential of the common electrode 21 is the same. That is, as shown in FIG. 4, it is considered that an image signal having a potential symmetrical to the common potential is applied to the dummy pixel electrode 9d between the positive polarity writing and the negative polarity writing. . Therefore, it is considered that an image signal having a potential symmetric with respect to the common potential is applied during the writing operation to the pixel electrode 9a between the positive polarity writing and the negative polarity writing. For this reason, since there is little or no flicker, the common potential supply circuit 137 does not need to adjust the common potential.

  On the other hand, if the output of the counter 135 when the positive polarity writing is performed on the dummy pixel electrode 9d and the output of the counter 135 when the negative polarity writing is performed on the dummy pixel electrode 9d are not equal, the positive polarity Between the potential of the image signal when the negative writing is performed and the common potential of the common electrode 21, and between the potential of the image signal when the negative writing is performed and the common potential of the common electrode 21 It is considered that the potential difference is not equal. That is, it is considered that an image signal having an asymmetric potential with respect to the common potential is applied to the dummy pixel electrode 9d between the positive polarity writing and the negative polarity writing. Accordingly, it is considered that an image signal having an asymmetric potential with respect to the common potential is applied between the positive polarity writing and the negative polarity writing also during the writing operation to the pixel electrode 9a. For this reason, flicker may occur or is already occurring, so the common potential supply circuit 137 adjusts the common potential.

  In this case, the output of the counter 135 when the positive polarity writing is performed on the dummy pixel electrode 9d is equal to the output of the counter 135 when the negative polarity writing is performed on the dummy pixel electrode 9d. The common potential is adjusted so that the common potential is shifted to the high potential side or the low potential side. In other words, the potential difference between the potential of the image signal when the positive polarity writing is performed and the common potential of the common electrode 21, and the potential of the image signal when the negative polarity writing is performed and the common potential of the common electrode 21. The common potential is adjusted so that the common potential is shifted to the high potential side or the low potential side so that the potential difference between the two is equal.

  Specifically, for example, when the positive polarity writing is performed on the dummy pixel electrode 9d, the output of the counter 135 is “12 clocks”, and the counter when the negative polarity writing is performed on the dummy pixel electrode 9d is performed. A case where the output of 135 is “9 clocks” will be described. In this case, the output of the counter 135 when the positive polarity writing is performed on the dummy pixel electrode 9d is larger than the output of the counter 135 when the negative polarity writing is performed on the dummy pixel electrode 9d. Therefore, as shown in FIG. 7, the potential difference V1 between the potential of the image signal when the positive polarity writing is performed and the common potential of the common electrode 21 is the potential of the image signal when the negative polarity writing is performed. And the common potential of the common electrode 21 is considered to be larger than the potential difference V2. This is because the common potential supplied to the common wiring line COM is shifted to a lower potential side as compared with the common potential that should be applied. Therefore, in the common potential supply circuit 137, the common potential is adjusted so as to shift the common potential to a relatively high potential side. The adjustment amount is the difference between the output of the counter 135 when the positive polarity writing is performed on the dummy pixel electrode 9d and the output of the counter 135 when the negative polarity writing is performed on the dummy pixel electrode 9d. This is based on the quantity (ie, “4 clocks”). That is, the difference between the output of the counter 135 when the positive polarity writing is performed on the dummy pixel electrode 9d and the output of the counter 135 when the negative polarity writing is performed on the dummy pixel electrode 9d becomes zero. Such an adjustment amount is calculated, and the common potential is adjusted so that the common potential is shifted to the high potential side by the calculated adjustment amount.

  On the other hand, for example, the output of the counter 135 when positive polarity writing is performed on the dummy pixel electrode 9d is “8 clocks”, and the output of the counter 135 when negative polarity writing is performed on the dummy pixel electrode 9d. Will be described as “10 clocks”. In this case, the output of the counter 135 when the positive polarity writing is performed on the dummy pixel electrode 9d is smaller than the output of the counter 135 when the negative polarity writing is performed on the dummy pixel electrode 9d. Therefore, as shown in FIG. 8, the potential difference V1 between the potential of the image signal when the positive polarity writing is performed and the common potential of the common electrode 21 is the potential of the image signal when the negative polarity writing is performed. And the common potential of the common electrode 21 is considered to be smaller than the potential difference V2. This is due to the fact that the common potential supplied to the common wiring line COM is shifted to the higher potential side compared to the original common potential. Therefore, in the common potential supply circuit 137, the common potential is adjusted so as to shift the common potential to a relatively low potential side. The adjustment amount is the difference between the output of the counter 135 when the positive polarity writing is performed on the dummy pixel electrode 9d and the output of the counter 135 when the negative polarity writing is performed on the dummy pixel electrode 9d. This is based on a quantity (ie, “2 clocks”). That is, the difference between the output of the counter 135 when the positive polarity writing is performed on the dummy pixel electrode 9d and the output of the counter 135 when the negative polarity writing is performed on the dummy pixel electrode 9d becomes zero. Such an adjustment amount is calculated, and the common potential is adjusted so that the common potential is shifted to the low potential side by the calculated adjustment amount.

  This common potential adjustment operation is performed during a period in which the writing operation to the image portion 70 is not performed. For example, the common potential adjustment operation is performed in the vertical blanking period. Thereafter, the writing operation to the pixel portion 70 is performed using the adjusted common potential.

  Therefore, in the liquid crystal device 100 according to the present embodiment, an image signal having a symmetric potential with respect to the common potential is applied to the pixel electrode 9a between the positive polarity writing and the negative polarity writing. . In other words, an image signal having an asymmetric potential with respect to the common potential is hardly or not applied to the pixel electrode 9a between the positive polarity writing and the negative polarity writing. Accordingly, it is possible to suitably suppress or prevent the occurrence of flicker and liquid crystal burn-in.

  In addition, since the common potential is automatically adjusted by the operation of the driver IC circuit 130, it is not necessary for the operator to manually adjust the common potential. Therefore, the accuracy of adjusting the common potential can be improved, and the common potential can be adjusted even after the liquid crystal device 100 is shipped from the manufacturing factory.

  Furthermore, instead of directly detecting a voltage that is relatively difficult to detect on the liquid crystal device 100 (or relatively difficult to detect because it is difficult to newly install a device that directly detects the voltage), Since the amount of charge that is easy to detect and the time required for the discharge are detected, it is possible to enjoy the advantage that the detection operation is relatively easy. Furthermore, since the detection accuracy can be improved as compared with a mode in which the voltage is directly detected, as a result, the common potential adjustment accuracy can be improved.

  In addition, if the current value supplied from the discharge constant current source 132 is adjusted, the discharge rate of the charge accumulated in the dummy pixel electrode 9d can be adjusted. That is, the slope of the charge amount in the discharge line D shown in FIGS. 5 and 6 can be adjusted. Therefore, the discharge process can be performed in a flexible manner in accordance with the specifications of the liquid crystal device 100 or various components (particularly, the driver IC circuit 100) included in the liquid crystal device 100. For example, in the case where one clock is a relatively long time, in order to accurately detect the time required for the remaining charge amount in the discharge line D to fall below the threshold voltage that is the output of the DC voltage source 133, It is preferable to relatively slow the discharge rate. On the other hand, when one clock is a relatively short time, it is necessary for the remaining charge amount in the discharge line D to fall below the threshold voltage that is the output of the DC voltage source 133, even if the discharge speed is not slowed down so much. Therefore, it is preferable to relatively increase the discharge speed in order to perform a rapid discharge process.

  Since the common potential is adjusted based on the result of writing and discharging in the dummy pixel portion 70d, the common potential adjustment operation is performed without affecting the normal image display operation using the pixel portion 70. It can be carried out.

  In addition, since the dummy pixel region 10d in which the dummy pixel unit 70d is provided is a region physically separated from the image display region 10a in which the pixel unit 70 is provided, a normal image display operation using the pixel unit 70 is performed. The above-described operation can be performed without affecting. This is an effect obtained also from the fact that the writing operation and the discharge process in the dummy pixel unit 70d are not performed during the image display operation using the pixel unit 70. As described above, as long as the dummy pixel area 10d is an area physically separated from the image display area 10a, the arrangement position of the dummy pixel area 10d is not particularly limited, but the dummy pixel area 70d is the same as the image display area 70. It is preferable to be disposed adjacent to at least one of the upper end and the lower end. However, if attention is paid to the fact that at least the common potential can be adjusted, the dummy pixel region 10d does not have to be physically separated from the image display region 10a. For example, even if the dummy pixel region 10d is configured to be mixed in the image display region 10a, at least the common potential can be adjusted. Similarly, paying attention to the point that it is sufficient to adjust at least the common potential, the writing operation and the discharging process in the dummy pixel unit 70d are performed in the middle of the image display operation using the pixel unit 70. It may be configured. In other words, the timing at which the writing operation and the discharge process in the dummy pixel portion 70d described above are merely an example, and even if these operations are performed at an arbitrary timing, at least the common potential can be adjusted. However, considering that the potential state in the dummy pixel portion 70d is not stable immediately after the write operation is performed, the discharge process is performed after a certain time has elapsed since the write operation was performed. Is preferred.

  Furthermore, a plurality of dummy pixel portions 70d are formed along the entire scanning line Yd (in other words, the same number of dummy lines as the number of all the data lines X1 to Xm intersecting with one dummy scanning line Yd). Therefore, a relatively large amount of charges can be accumulated in the plurality of dummy pixel portions 70 as a whole. Therefore, it is possible to relatively improve the accuracy of detection of the time required for discharging the charge accumulated in the dummy pixel electrode 9d using the comparator 134 and the counter 135. As a result, the common potential adjustment accuracy can be improved. However, paying attention to the point that it is sufficient to adjust at least the common potential, it is not necessary to form the plurality of dummy pixel portions 70d over the entire horizontal line. For example, a plurality of dummy pixel portions 70d are formed along a part of one horizontal line (in other words, some of the data lines X1 to Xm intersecting one dummy scanning line Yd Even if the same number of dummy pixel portions 70d are formed), the common potential can be adjusted at least. Similarly, in view of the fact that at least the common potential can be adjusted, a single dummy pixel portion 70d may be provided.

  Further, since writing to the dummy pixel electrode 9d is performed using an image signal having a writing potential corresponding to the maximum gradation, a relatively large amount of charge can be accumulated in the dummy pixel electrode 9d. Therefore, it is possible to relatively improve the accuracy of detection of the time required for discharging the charge accumulated in the dummy pixel electrode 9d using the comparator 134 and the counter 135. As a result, the common potential adjustment accuracy can be improved. However, in view of the point that it is sufficient to adjust at least the common potential, the dummy pixel electrode 9d may be written using an image signal having an arbitrary writing potential. .

  In the above description, a plurality of dummy pixel portions 70d are provided along one dummy scanning line Yd extending in the horizontal direction, but a plurality of dummy scanning lines Yd are provided and the plurality of dummy scanning lines are provided. A plurality of dummy pixel portions 70d may be provided along the line Yd. As a result, a relatively large amount of charge can be accumulated in the plurality of dummy pixel portions 70 as a whole. Therefore, it is possible to relatively improve the accuracy of detection of the time required for discharging the charge accumulated in the dummy pixel electrode 9d using the comparator 134 and the counter 135. As a result, the common potential adjustment accuracy can be improved.

(5) Electronic Device Next, an example of an electronic device including the liquid crystal device 100 described above will be described with reference to FIGS. 9 and 10.

  FIG. 9 is a perspective view of a mobile personal computer to which the liquid crystal device 100 described above is applied. In FIG. 11, a computer 1200 includes a main body 1204 provided with a keyboard 1202 and a liquid crystal display unit 1206 including the liquid crystal device 100 described above. The liquid crystal display unit 1206 is configured by adding a backlight to the back surface of the liquid crystal device 100.

  Next, an example in which the above-described liquid crystal device 100 is applied to a mobile phone will be described. FIG. 10 is a perspective view of a mobile phone which is an example of an electronic apparatus. In FIG. 10, a cellular phone 1300 includes a liquid crystal device 1005 that adopts a transflective display format and has the same configuration as the liquid crystal device 100 described above, together with a plurality of operation buttons 1302.

  Since these electronic devices also include the liquid crystal device 100 described above, the various effects described above can be suitably enjoyed.

  In addition to the electronic devices described with reference to FIGS. 9 and 11, a liquid crystal television, a viewfinder type or a monitor direct-view type video tape recorder, a car navigation device, a pager, an electronic notebook, a calculator, a word processor, a workstation And a direct-view display device including a video phone, a POS terminal, and a touch panel, and a projection display device such as a liquid crystal projector. Needless to say, the present invention can be applied to these various electronic devices.

  The present invention is not limited to the above-described embodiments, and various modifications can be made as appropriate without departing from the spirit or concept of the invention that can be read from the claims and the entire specification. Devices and electronic devices are also included in the technical scope of the present invention.

It is a top view which shows the structure of the liquid crystal device which concerns on embodiment. It is H-H 'sectional drawing of FIG. It is a block diagram which shows notionally the electrical structure of the principal part of the liquid crystal device which concerns on this embodiment. 4 is a graph showing an image signal potential and a common potential applied during a writing operation by the liquid crystal device according to the embodiment. 6 is a timing chart showing the operation of the liquid crystal device when positive writing is performed on a dummy pixel electrode. 6 is a timing chart showing the operation of the liquid crystal device when negative polarity writing is performed on a dummy pixel electrode. It is a graph which shows notionally adjustment operation of a common potential. It is a graph which shows notionally adjustment operation of a common potential. It is a perspective view of a mobile personal computer to which a liquid crystal device is applied. 1 is a perspective view of a mobile phone to which a liquid crystal device is applied.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Liquid crystal device, 9a ... Pixel electrode, 9d ... Dummy pixel electrode, 10a ... Image display area, 10d ... Dummy pixel area, 21 ... Common electrode, 101 ... Data line drive circuit, 104 ... Scanning line drive circuit, 121, Discharge Switching TFT, 130 ... driver IC circuit, 134 ... comparator, 135 ... counter, 136 ... comparator, common potential supply circuit ... 137, Y1-Yn ... scanning line, Yd ... dummy scanning line, COM ... common wiring, A ... Detection timing signal line, D ... discharge line

Claims (13)

A pixel portion arranged in the image display area;
A dummy pixel unit disposed in a dummy pixel region located around the image display region;
For the dummy pixel portion, the positive writing in which the writing potential to the dummy pixel electrode included in the dummy pixel portion is higher than the common potential supplied to the common electrode, and the writing to the dummy pixel electrode Writing means for performing negative polarity writing in which a writing potential is on a lower potential side than the common potential;
The positive discharge time, which is the time required for discharging the charge accumulated in the dummy pixel electrode on which the positive polarity writing has been performed, and the charge accumulated on the dummy pixel electrode in which the negative polarity writing has been performed. Detection means for detecting each of the negative polarity discharge times, which is the time required for discharge;
An electro-optical device comprising: a correcting unit that corrects the common potential so that the positive discharge time and the negative discharge time are equal. The detection means includes
A comparator for comparing the amount of charge accumulated in the dummy pixel electrode with a predetermined value, and a counter for counting the number of clock pulses rising at a predetermined period;
Until the comparator determines that the amount of charge accumulated in the dummy pixel electrode falls below the predetermined value after the discharge of the charge accumulated in the dummy pixel electrode on which the positive address has been performed starts. During the period, the number of clock pulses counted by the counter is detected as the positive discharge time,
Until the comparator determines that the amount of charge accumulated in the dummy pixel electrode falls below the predetermined value after the discharge of the charge accumulated in the dummy pixel electrode on which the negative polarity writing has been performed is started. 2. The electro-optical device according to claim 1, wherein the number of clock pulses counted by the counter is detected as the negative discharge time.   The electro-optical device according to claim 1, wherein the detection unit further includes a discharge constant current source for discharging the charge accumulated in the dummy pixel electrode. A plurality of the pixel portions are arranged in a matrix corresponding to the intersection of the scanning lines and the data lines,
4. The electro-optical device according to claim 1, wherein a plurality of the dummy pixel portions are arranged along the scanning line. 5.   The electro-optical device according to claim 1, wherein a light shielding film is formed in the dummy pixel portion.   The electro-optical device according to claim 1, wherein the dummy pixel region is provided so as to be adjacent to at least one of both ends of the image display region.   7. The electricity according to claim 1, wherein the writing unit performs the positive polarity writing and the negative polarity writing using a writing potential corresponding to a maximum gradation. Optical device.   The correction means corrects the common potential so that the common potential is changed to a relatively high potential side when the positive discharge time is longer than the negative discharge time, and the negative discharge time is corrected. The said common electric potential is correct | amended so that the said common electric potential may be changed to a relatively low electric potential side when it is longer than the said positive polarity discharge time, The Claim 1 characterized by the above-mentioned. Electro-optic device.   The detection means detects the positive discharge time after starting to discharge the charge accumulated in the dummy pixel electrode after a predetermined period has elapsed since the positive writing is performed, and the negative electrode 9. The negative discharge time is detected after the discharge of the electric charge accumulated in the dummy pixel electrode is started after a predetermined period has elapsed since the sexual writing was performed. The electro-optical device according to any one of the above.   The electro-optical device according to claim 9, wherein the predetermined period is one vertical scanning period. The writing means performs the positive polarity writing or the negative polarity writing only for one horizontal scanning period,
The electro-optical device according to claim 1, wherein the detection unit performs detection of the positive discharge time or detection of the negative discharge time for only one horizontal period. The writing means performs the positive polarity writing or the negative polarity writing on the dummy pixel portion before or after writing to the pixel portion,
12. The detection unit according to claim 1, wherein the detection unit detects the positive discharge time or the negative discharge time before or after writing to the pixel unit. The electro-optical device according to 1.   An electronic apparatus comprising the electro-optical device according to claim 1.

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