JP2007212605A - Electro-optical device and electronic equipment - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an electro-optical device and electronic equipment capable of alleviating flicker and image persistence. <P>SOLUTION: An electro-optical device 1 comprises scanning lines, data lines, and pixels arranged correspondingly to the intersections of the scanning lines and the data lines. The pixel includes a pixel electrode, a common electrode facing the pixel electrode, and a TFT which brings the data line and the pixel electrode into conduction when a selection voltage is applied to the scanning line. The electro-optical device 1 comprises a scanning line driving circuit 30 for supplying a selection voltage for selecting the scanning lines in predetermined order, and a data line driving circuit 40 for supplying an image signal to a data line when a scanning line is selected. As the selection voltage, the scanning line driving circuit 30 supplies a first voltage for a first period, and supplies a second voltage lower than the first voltage but higher than the amplitude of the image signal for a second period after the end of the first period. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an electro-optical device and an electronic apparatus.

  2. Description of the Related Art Conventionally, electro-optical devices such as liquid crystal display devices that display images are known. Such an electro-optical device has the following configuration, for example.

  The electro-optical device includes a liquid crystal panel, a liquid crystal driving circuit that drives the liquid crystal panel, and a control circuit that controls the liquid crystal driving circuit. The liquid crystal driving circuit includes a scanning line driving circuit, a data line driving circuit, and a liquid crystal driving power supply circuit.

  The liquid crystal panel is provided between an element substrate on which a thin film transistor (hereinafter referred to as TFT) as a switching element (hereinafter referred to as TFT), which will be described later, is arranged in a matrix, a counter substrate disposed opposite to the element substrate, and the element substrate and the counter substrate. And a liquid crystal as an electro-optical material.

  The element substrate is provided with a plurality of scanning lines provided at predetermined intervals, a plurality of data lines provided substantially orthogonally to the scanning lines and at predetermined intervals, and substantially parallel and alternately with the plurality of scanning lines. A capacitor line.

Pixels are provided at intersections between the scanning lines and the data lines. In addition to the above-described TFT, the pixel includes a pixel electrode and a storage capacitor having one end connected to the pixel electrode and the other end connected to a capacitor line. A plurality of pixels are arranged in a matrix to form a display area.
A scanning line is connected to the gate of the TFT, a data line is connected to the source of the TFT, and a pixel electrode and a storage capacitor are connected to the drain of the TFT.

  The counter substrate is provided with a plurality of common lines substantially parallel to the plurality of scanning lines. Further, common electrodes are formed on the counter substrate so as to face the pixel electrodes, and these common electrodes are connected to a common line.

  The above electro-optical device operates as follows. That is, all the pixels related to a predetermined scanning line are selected by supplying the selection voltage line-sequentially. Then, an image signal is supplied to the data line in synchronization with the selection of the pixel. As a result, the image signal is supplied to all the pixels selected by the selection voltage, and the image data is written into the pixel electrode.

  In this electro-optical device, with the common electrode voltage as a reference voltage, positive writing for supplying an image signal to the data line at a voltage higher than the common electrode voltage, and the data line at a voltage lower than the common electrode voltage The negative polarity writing for supplying the image signal to the alternating current is alternately performed.

When an image signal is written to the pixel electrode of the pixel, a driving voltage is applied to the liquid crystal due to a potential difference between the pixel electrode and the common electrode. Therefore, by changing the voltage level of the image signal, the orientation and order of the liquid crystal are changed, and gradation display is performed by light modulation of each pixel.
Note that the driving voltage applied to the liquid crystal is held by a storage capacitor for a period that is three orders of magnitude longer than the period during which the image signal is written.

  Here, in the above electro-optical device, parasitic capacitance is generated between the gate and drain of the TFT and between the source and drain, respectively. When the gate voltage of the TFT is turned off, the charge stored in the storage capacitor and the charge stored in the pixel capacitor by the pixel electrode and the common electrode are redistributed including the parasitic capacitance. As a result, so-called push-down in which the voltage of the pixel electrode is reduced occurs.

  This pushdown always occurs both in the positive polarity writing and in the negative polarity writing. Then, the voltage of the pixel electrode (hereinafter referred to as push-down voltage) that decreases due to this push-down becomes higher as it becomes closer to the scanning line driving circuit. For this reason, the pushdown voltage at each pixel in the display region becomes non-uniform. Therefore, since the average value of the voltage applied to the liquid crystal in each pixel is not constant, flicker occurs in the display area.

In order to solve this problem, there is an electro-optical device that reduces flicker in a display area using a filter (see, for example, Patent Document 1).
That is, in the electro-optical device disclosed in Patent Document 1, a low-pass filter and a high-pass filter are provided between the scanning line driving circuit and the pixel, and the low-passing frequency of the selection voltage supplied from the scanning line driving circuit. Only what is common to the filter and the high-pass filter is supplied to each pixel.
Thereby, the frequency band of the selection voltage supplied to each pixel is narrowed, the pushdown voltage in each pixel is made uniform, and flicker in the display area is reduced.
Japanese Patent Laid-Open No. 7-56531

By the way, when the above-described pushdown occurs, the center voltage Vc of the image signal becomes lower than the voltage of the common electrode by the pushdown voltage. For this reason, the push-down voltage is always applied to the liquid crystal, and there is a possibility that image sticking will occur in the display area.
The electro-optical device disclosed in Patent Document 1 described above equalizes the pushdown voltage in each pixel to reduce flicker, but is not configured to reduce the pushdown voltage. Therefore, the pushdown voltage is applied to the liquid crystal, and the burn-in in the display area cannot be reduced.

  An object of the present invention is to provide an electro-optical device and an electronic apparatus that can reduce flicker and burn-in in a display area.

  The electro-optical device of the present invention is an electro-optical device including a plurality of scanning lines, a plurality of data lines, and a plurality of pixels provided corresponding to intersections of the scanning lines and the data lines. The pixel includes a pixel electrode, a common electrode facing the pixel electrode, and a switching element that brings the data line and the pixel electrode into a conductive state when a selection voltage is applied to the scanning line. A scanning line driving circuit for supplying the selection voltage for selecting the scanning lines in a predetermined order; and a data line driving circuit for supplying an image signal to the data line when the scanning line is selected. The scanning line driving circuit supplies a first voltage as the selection voltage in a first period, and the image is lower than the first voltage in a predetermined second period from the end of the first period. Second voltage higher than signal amplitude And supplying.

  According to the present invention, the electro-optical device supplies the first voltage as the selection voltage in the first period by the scanning line driving circuit, and the first voltage in the predetermined second period from the end of the first period. A second voltage lower than the voltage and higher than the amplitude of the image signal is supplied. That is, in a state where the first voltage is applied to the switching element, the switching element becomes conductive, and image data based on the image signal is written to the pixel electrode. On the other hand, in a state where the second voltage is applied to the switching element, the switching element is in a semiconductive state between the conductive state and the nonconductive state. In this case, when the state is changed from the conductive state to the semiconductive state, pushdown occurs and the voltage of the pixel electrode is reduced. However, the voltage of the pixel electrode can be recovered during the period when the switching element is in the semiconductive state. Therefore, since the final pushdown voltage can be reduced, flicker and burn-in in the display area can be reduced.

  In the electro-optical device according to the aspect of the invention, it is preferable that the scanning line driving circuit adjusts the potential of the second voltage.

  According to the present invention, the potential of the second voltage supplied to the scanning line is adjusted by the scanning line driving circuit. Thereby, since the level of the semiconducting state of the switching element by the second voltage can be adjusted, the pushdown voltage can be reliably reduced.

  In the electro-optical device according to the aspect of the invention, it is preferable that the scanning line driving circuit adjusts the second period.

  According to the present invention, the second period, that is, the period during which the second voltage is supplied to the scanning line is adjusted by the scanning line driving circuit. Thereby, the balance between the conduction state of the switching element by the first voltage and the semi-conduction state of the switching element by the second voltage can be adjusted, so that the pushdown voltage can be reliably reduced.

  The electro-optical device of the present invention includes a plurality of scanning lines, a plurality of data lines, and a plurality of pixels provided corresponding to intersections of the scanning lines and the data lines, and displays a full screen. An electro-optical device capable of selecting a full-screen display mode and a partial display mode in which a part of the whole screen is a display area and another area is a non-display area. A common electrode facing the pixel electrode, and a switching element that brings the data line and the pixel electrode into a conductive state when a selection voltage is applied to the scan line, A scanning line driving circuit for supplying the selection voltage to be selected in order; and a data line driving circuit for supplying an image signal to the data line when the scanning line is selected. , As the selection voltage, In the display mode, the first voltage is supplied. In the partial display mode, the first voltage is supplied in the first period. The first voltage is lower than the first voltage in a predetermined second period from the end of the first period. A second voltage is supplied.

  According to the present invention, in the partial display mode, the electro-optical device supplies the first voltage as the selection voltage by the scanning line driving circuit in the first period, and the predetermined second from the end of the first period. A second voltage lower than the first voltage is supplied during the period. That is, in a state where the first voltage is applied to the switching element, the switching element becomes conductive, and image data based on the image signal is written to the pixel electrode. On the other hand, in a state where the second voltage is applied to the switching element, the switching element is in a semiconductive state between the conductive state and the nonconductive state. In this case, when the state is changed from the conductive state to the semiconductive state, pushdown occurs and the voltage of the pixel electrode is reduced. However, the voltage of the pixel electrode can be recovered during the period when the switching element is in the semiconductive state. Accordingly, since the final pushdown voltage in the partial display mode can be reduced, flicker and burn-in in the display area can be reduced.

  In the electro-optical device according to the aspect of the invention, the data line driving circuit supplies the image signal to the data line at a voltage higher than the voltage applied to the common electrode when the scanning line is selected. It is preferable to alternately perform the negative polarity writing for supplying the image signal to the data line at a voltage lower than the voltage applied to the common electrode.

  According to the present invention, the electro-optical device supplies the selection voltage to the scanning line by the scanning line driving circuit in a line sequential manner, and the data line driving circuit supplies the image signal to the data line at a voltage higher than the voltage of the common electrode. And the negative polarity writing for supplying the image signal to the data line at a voltage lower than the voltage of the common electrode are alternately performed. Therefore, since the polarity of the voltage applied to the electro-optical material can be reversed, the burn-in of the display area can be further reduced by changing the arrangement of the electro-optical material every predetermined period.

  In the electro-optical device according to the aspect of the invention, in the full-screen display mode, the data line driving circuit has a positive polarity and a negative polarity with respect to the data line with reference to a predetermined voltage higher than a voltage applied to the common electrode. In the partial display mode, the data line driving circuit supplies positive and negative image signals to the data line with reference to a voltage applied to the common electrode. Are preferably supplied alternately.

According to the present invention, in the full screen display mode, the electro-optical device supplies the selection voltage to the scanning lines line-sequentially by the scanning line driving circuit, and the voltage applied to the common electrode by the data line driving circuit. Also, positive and negative image signals are alternately supplied to the data lines with a predetermined high voltage as a reference. For this reason, the data line driving circuit alternately supplies positive and negative image signals to the data line with reference to a voltage that is higher than the voltage applied to the common electrode by the final pushdown voltage. Thus, the center voltage Vc of the image signal can be made higher than the voltage of the common electrode by the final pushdown voltage. Therefore, in the full screen display mode, flicker and burn-in in the display area can be reduced.
On the other hand, in the partial display mode, the electro-optical device supplies the selection voltage to the scanning lines line-sequentially by the scanning line driving circuit, while the data line driving circuit uses the voltage applied to the common electrode as a reference to the data line. On the other hand, positive and negative image signals are alternately supplied. Therefore, the voltage applied to the common electrode is the same as the voltage of the image signal, so that power consumption can be reduced in the non-display area.

In the electro-optical device according to the aspect of the invention, it is preferable that the scanning line driving circuit adjusts the potential of the second voltage in a range larger than the amplitude of the image signal.
According to the present invention, the potential of the second voltage supplied to the scanning line is adjusted by the scanning line driving circuit in a range larger than the amplitude of the image signal. Thereby, since the level of the conduction state of the switching element by the second voltage can be adjusted, the pushdown voltage can be reliably reduced.

In the electro-optical device according to the aspect of the invention, it is preferable that the scanning line driving circuit adjusts the second period.
According to the present invention, there are effects similar to those described above.

  The electro-optical device according to the aspect of the invention further includes a power supply circuit that generates the first voltage and the second voltage, and the power supply circuit boosts the input voltage to generate the first voltage and the second voltage. It is preferable to provide a charge pump circuit to be generated.

  According to this invention, the electro-optical device is provided with the power supply circuit having the charge pump circuit that generates the first voltage and the second voltage. Therefore, the electro-optical device can generate the first voltage and the second voltage if there is one power supply circuit. Therefore, there are cases where the circuit scale and power consumption can be reduced as compared with the case where two power supply circuits, ie, a power supply circuit that generates the first voltage and a power supply circuit that generates the second voltage are required.

An electronic apparatus according to an aspect of the invention includes the above-described electro-optical device.
According to the present invention, there are effects similar to those described above.

Hereinafter, embodiments of the present invention will be described with reference to the drawings. In the following description of embodiments and modifications, the same constituent elements are denoted by the same reference numerals, and the description thereof is omitted or simplified.
<First Embodiment>
FIG. 1 is a block diagram showing a configuration of an electro-optical device 1 according to the first embodiment of the present invention.
The electro-optical device 1 includes a liquid crystal panel AA, a liquid crystal driving circuit 10 that drives the liquid crystal panel AA, and a control circuit 20 that controls the liquid crystal driving circuit 10. The liquid crystal driving circuit 10 includes a scanning line driving circuit 30, a data line driving circuit 40, and a liquid crystal driving power supply circuit 50.

FIG. 2 is a partially enlarged plan view of the liquid crystal panel AA.
The liquid crystal panel AA includes an element substrate 100 in which thin film transistors (hereinafter referred to as TFTs) 151 as switching elements, which will be described later, are arranged in a matrix, a counter substrate 200 arranged to face the element substrate 100, an element substrate 100, And a liquid crystal as an electro-optical material provided between the counter substrates 200 (see FIG. 1).
The above-described liquid crystal drive circuit 10 is formed on a silicon substrate, and is mounted on the substrate of the liquid crystal panel AA by COG (Chip On Glass) or the like.

  The element substrate 100 includes a plurality of scanning lines 110 provided at predetermined intervals, a plurality of data lines 120 provided substantially orthogonal to the scanning lines 110 at predetermined intervals, and substantially parallel to the plurality of scanning lines 110. And capacitor lines 140 provided alternately. In FIG. 2, scanning lines 110A, 110B, and 110C are sequentially arranged from the top of the scanning lines 110, and data lines 120A and 120B are sequentially arranged from the left of the data lines 120.

Pixels 150 are provided at the intersections between the scanning lines 110 and the data lines 120. In addition to the above-described TFT 151, the pixel 150 includes a pixel electrode 155 and a storage capacitor 153 having one end connected to the pixel electrode 155 and the other end connected to the capacitor line 140.
The scanning line 110 is connected to the gate of the TFT 151, the data line 120 is connected to the source of the TFT 151, and the pixel electrode 155 and the storage capacitor 153 are connected to the drain of the TFT 151. The TFT 151 intermittently connects the data line 120 to the pixel electrode 155 and the storage capacitor 153 according to the selection voltage from the scanning line 110.

  The counter substrate 200 is provided with a plurality of common lines 130 substantially parallel to the plurality of scanning lines 110. A common electrode 156 is formed on the counter substrate 200 so as to face the pixel electrode 155, and the common electrode 156 is connected to the common line 130.

The scanning line driving circuit 30 supplies, as the selection voltage, the first voltage that makes the TFT 151 conductive or the second voltage that makes the TFT 151 semi-conductive to each scanning line 110 line-sequentially.
For example, when a first voltage is supplied as a selection voltage to a certain scanning line 110, all the TFTs 151 connected to the scanning line 110 become conductive, and the pixel electrode 155 and accumulation of the pixel 150 related to the scanning line 110 are stored. The capacitor 153 and the data line 120 are brought into conduction. When a second voltage is supplied as a selection voltage to a certain scanning line 110, all TFTs 151 connected to the scanning line 110 are in a semi-conducting state, and the pixel electrode 155 of the pixel 150 related to the scanning line 110 and The storage capacitor 153 and the data line 120 are in a semiconductive state.

  The data line driving circuit 40 supplies an image signal to each data line 120 and sequentially writes the image data to the pixel electrode 155 of the pixel 150 via the TFT 151 in the conductive state or the semiconductive state.

The control circuit 20 includes an image data conversion unit 21.
The image data converter 21 boosts the input image signal by the final push-down voltage and outputs it to the data line driving circuit 40.

The above electro-optical device 1 operates as follows.
The scanning line driving circuit 30 supplies the first voltage or the second voltage as the selection voltage to the scanning lines 110 in a line sequential manner, thereby selecting the pixels 150 related to one scanning line 110 collectively. In synchronization with the selection of the pixel 150, the data line driving circuit 40 supplies an image signal to the data line 120. As a result, the image signal is supplied to all the pixels selected by the scanning line driving circuit 30 and the image data is written into the pixel electrode 155.

When image data is written to the pixel electrode 155, a driving voltage is applied to the liquid crystal due to a potential difference between the pixel electrode 155 and the common electrode 156. Therefore, by changing the voltage level of the image signal, the orientation and order of the liquid crystal are changed, and gradation display is performed by light modulation of each pixel.
Note that the driving voltage applied to the liquid crystal is held by the storage capacitor 153 for a period longer by three digits than the period during which the image signal is written.

FIG. 3 is a timing chart of the electro-optical device 1.
In FIG. 3, GATE1 is the voltage of the scanning line 110A, DATA1 is the voltage of the data line 120A, and PIX1 is the voltage of the pixel electrode 155 provided at the intersection of the scanning line 110A and the data line 120A. VCOM is the voltage of the common electrode 156, and Vc is the minimum value of the image signal.
In FIG. 3, GATE1A, DATA1A, and PIX1A are the voltages of the pixel electrodes provided at the intersections of the scanning lines, data lines, scanning lines, and data lines of the conventional electro-optical device, respectively.
In FIG. 3, the potential difference between the voltage VP1 and the voltage VP2, the potential difference between the voltage VP2 and the voltage VP3, the potential difference between the voltage VP3 and the voltage VP4, and the potential difference between the voltage VP4 and the voltage VP5 are the same.
In FIG. 3, the same gradation is used for easy understanding.
Further, the minimum voltage Vc of the image signal is higher than the voltage VCOM of the common electrode 156 by the push-down voltage.

First, during a period from time t1 to t2, the scanning line driving circuit 30 supplies the first voltage as the selection voltage to the scanning line 110A, the voltage GATE1 of the scanning line 110A is set to VgH1, and one horizontal line related to the scanning line 110A is obtained. All the TFTs 151 in the line are turned on.
At the same time, the data line driving circuit 40 supplies an image signal to the data line 120A at a voltage higher than the voltage VCOM of the common electrode 156, and writes image data to the pixel electrode 155 via the conductive TFT 151. Then, the voltage PIX1 of the pixel electrode 155 becomes VP1, and a potential difference between the voltage VP1 and the voltage VCOM of the common electrode 156 is applied to the liquid crystal.

  Next, at time t2, the scanning line driving circuit 30 supplies the second voltage as the selection voltage to the scanning line 110A, the voltage GATE1 of the scanning line 110A is set to VgH2, and the TFT 151 of one horizontal line related to the scanning line 110A. Are all made semi-conductive. Here, VgH2 is set within a voltage range that is higher than the amplitude of the image signal DATA1 with respect to the voltage VCOM of the common electrode 156 and lower than VgH1. Then, when the TFT 151 changes from the conductive state to the semi-conductive state, the charges accumulated in the storage capacitor 153 and the charges accumulated in the pixel capacitor by the pixel electrode 155 and the common electrode 156 become the parasitic capacitances Cgs and Cds. Including redistribution, resulting in pushdown. Accordingly, the voltage PIX1 of the pixel electrode 155 decreases to VP3, and a potential difference between the voltage VP3 and the voltage VCOM of the common electrode 156 is applied to the liquid crystal.

Next, during the period from time t2 to time t3, the scanning line driving circuit 30 supplies the second voltage as the selection voltage to the scanning line 110A, the voltage GATE1 of the scanning line 110A is set to VgH2, and 1 relating to the scanning line 110A. All the TFTs 151 in the horizontal line are made semiconductive.
At the same time, the data line driving circuit 40 supplies an image signal to the data line 120A at a voltage higher than the voltage VCOM of the common electrode 156, and the image data is supplied to the pixel electrode 155 and the storage capacitor 153 via the TFT 151 in the semiconductive state. Write. Then, the voltage PIX1 of the pixel electrode 155 recovers to VP2 during the period in which the TFT 151 is in a semi-conducting state, and a potential difference between the voltage VP2 and the voltage VCOM of the common electrode 156 is applied to the liquid crystal.

  Next, at time t3, the scanning line driving circuit 30 sets the voltage GATE1 of the scanning line 110A to VgL, and turns off all the TFTs 151 of one horizontal line related to the scanning line 110A. Then, when the TFT 151 changes from the semi-conducting state to the non-conducting state, the charges accumulated in the storage capacitor 153 and the charges accumulated in the pixel capacitor by the pixel electrode 155 and the common electrode 156 are parasitic capacitances Cgs, Cds. Redistribution including a pushdown occurs. Accordingly, the voltage PIX1 of the pixel electrode 155 decreases to VP4, and the potential difference between the voltage VP4 and the voltage VCOM of the common electrode 156 is applied to the liquid crystal.

  Next, the operation from time t4 to t5 is performed in the same manner as the above-described period from time t1 to t2. Then, the voltage PIX1 of the pixel electrode 155 becomes VP1, and a potential difference between the voltage VP1 and the voltage VCOM of the common electrode 156 is applied to the liquid crystal.

  Next, at time t5, the operation is similar to that at time t2. Then, the voltage PIX1 of the pixel electrode 155 decreases to VP3, and a potential difference between the voltage VP3 and the voltage VCOM of the common electrode 156 is applied to the liquid crystal.

  Next, the operation from time t5 to t6 is performed in the same manner as the above-described period from time t2 to t3. Then, the voltage PIX1 of the pixel electrode 155 recovers to VP2 during the period in which the TFT 151 is in a semi-conducting state, and a potential difference between the voltage VP2 and the voltage VCOM of the common electrode 156 is applied to the liquid crystal.

  Next, at time t6, the operation is similar to that at time t3 described above. Then, the voltage PIX1 of the pixel electrode 155 decreases to VP4, and a potential difference between the voltage VP4 and the voltage VCOM of the common electrode 156 is applied to the liquid crystal.

According to this embodiment, there are the following effects.
(1) The electro-optical device 1 supplies the first voltage as a selection voltage in the period from time t1 to t2 in FIG. 3 by the scanning line driving circuit 30, and after the period from time t1 to t2 ends. In the period from time t2 to t3, a second voltage lower than the first voltage and higher than the amplitude of the image signal DATA1 with reference to the voltage VCOM of the common electrode 156 is supplied. That is, in a state where the first voltage is applied to the TFT 151, the TFT 151 becomes conductive, and image data based on an image signal is written to the pixel electrode 155. On the other hand, in a state where the second voltage is applied to the TFT 151, the TFT 151 is in a semi-conductive state between the conductive state and the non-conductive state. In this case, when the conductive state changes to the semiconductive state, that is, at time t2, pushdown occurs, and the voltage PIX1 of the pixel electrode 155 decreases from VP1 to VP3. However, the voltage PIX1 of the pixel electrode 155 can be recovered from VP3 to VP2 during the period from time t2 to t3 when the TFT 151 is in a semi-conducting state.
In addition, the electro-optical device 1 supplies the first voltage as a selection voltage in the period from time t4 to t5 in FIG. 3 by the scanning line driving circuit 30, and after the period from time t4 to t5 ends. In the period from time t5 to t6, a second voltage lower than the first voltage and higher than the amplitude of the image signal DATA1 with reference to the voltage VCOM of the common electrode 156 is supplied. Then, similarly to the above-described time t2, at time t5 when the TFT 151 changes from the conductive state to the semi-conductive state, pushdown occurs, and the voltage PIX1 of the pixel electrode 155 decreases from VP1 to VP3. However, the voltage PIX1 of the pixel electrode 155 can be recovered from VP3 to VP2 during the period from time t5 to t6 when the TFT 151 is in the semi-conducting state, similarly to the period from time t2 to t3.
Therefore, since the final pushdown voltage can be reduced, flicker and burn-in in the display area can be reduced.

Second Embodiment
FIG. 4 is a block diagram showing a configuration of an electro-optical device 1A according to the second embodiment of the present invention.
The electro-optical device 1A is different from the electro-optical device 1 in FIG. 1 in the configuration of a control circuit 20A that controls the liquid crystal drive circuit 10.

The control circuit 20A includes an image data conversion unit 21A and a display control unit 22.
Based on the input display switching signal, the display control unit 22 makes a full screen display mode in which the entire display screen is a display area, and sets a part of the display screen as a display area and hides other areas. One of the partial display modes as the region is selected, and the selected display mode is output to the scanning line driving circuit 30 as a mode selection signal.

  The image data conversion unit 21A converts the input image signal according to positive polarity writing or negative polarity writing. Then, in the full screen display mode, the converted image signal is boosted by the final pushdown voltage and output to the data line driving circuit 40. The converted image signal is output to the data line driving circuit 40 as it is in the partial display mode.

The electro-optical device 1A described above operates as follows in the full-screen display mode.
The scanning line driving circuit 30 supplies the first voltage as the selection voltage to the scanning lines 110 in a line sequential manner, thereby selecting the pixels 150 related to one scanning line 110 collectively. In synchronization with the selection of the pixel 150, the data line driving circuit 40 supplies an image signal to the data line 120. As a result, the image signal is supplied to all the pixels selected by the scanning line driving circuit 30 and the image data is written into the pixel electrode 155.

When image data is written to the pixel electrode 155, a driving voltage is applied to the liquid crystal due to a potential difference between the pixel electrode 155 and the common electrode 156. Therefore, by changing the voltage level of the image signal, the orientation and order of the liquid crystal are changed, and gradation display is performed by light modulation of each pixel.
Note that the driving voltage applied to the liquid crystal is held by the storage capacitor 153 for a period longer by three digits than the period during which the image signal is written.

Further, the electro-optical device 1A described above operates as follows in the partial display mode.
FIG. 5 is a diagram showing a display screen of the liquid crystal panel AA in the partial display mode.
In the partial display mode, the display screen 70 of the liquid crystal panel AA is divided into a display area 71 and a non-display area 72 provided across the display area 71. The display area 71 displays the remaining battery level and time, and the non-display area 72 displays nothing. That is, in the non-display area 72, white is displayed in the case of normally white, and black is displayed in the case of normally black.

In such a partial display mode, the display area is narrower than in the full-screen display mode, but one frame period does not change. Therefore, in the display area 71, the selection period per one scanning line 110 is longer than the selection period per one scanning line 110 in the full screen display mode.
Further, since nothing is displayed in the non-display area 72, the frame is updated less frequently than the display area 71.

  Hereinafter, the operation of the electro-optical device 1A in the full screen display mode and the partial display mode will be described with reference to FIGS.

FIG. 6 is a timing chart in the full screen display mode of the electro-optical device 1A.
For comparison with the electro-optical device 1, the selection period of one horizontal line in the full-screen display mode of the electro-optical device 1A is equal to the selection period of one horizontal line of the electro-optical device 1 described above. Specifically, the period from time t11 to t13 in FIG. 6 is equal to the period from time t1 to t3 in FIG.

In FIG. 6, in order to facilitate understanding, writing is performed with the same gradation in both positive writing and negative writing.
In this full screen display mode, the center voltage Vc of the image signal is higher than the voltage VCOM of the common electrode 156 by the push-down voltage.

First, positive polarity writing is performed during a period from time t11 to t13. That is, the scanning line driving circuit 30 supplies the first voltage as the selection voltage to the scanning line 110A, sets the voltage GATE1 of the scanning line 110A to VgH1, and turns on all the TFTs 151 of one horizontal line related to the scanning line 110A. To do.
At the same time, the data line driving circuit 40 supplies an image signal to the data line 120A at a voltage higher than the voltage VCOM of the common electrode 156, and writes image data to the pixel electrode 155 via the conductive TFT 151. Then, the voltage PIX1 of the pixel electrode 155 becomes VP1, and a potential difference between the voltage VP1 and the voltage VCOM of the common electrode 156 is applied to the liquid crystal.

  Next, at time t13, the scanning line driving circuit 30 sets the voltage GATE1 of the scanning line 110A to VgL, and turns off all the TFTs 151 of one horizontal line related to the scanning line 110A. Then, when the TFT 151 changes from the semi-conducting state to the non-conducting state, the charges accumulated in the storage capacitor 153 and the charges accumulated in the pixel capacitor by the pixel electrode 155 and the common electrode 156 are parasitic capacitances Cgs, Cds. Redistribution including a pushdown occurs. Accordingly, the voltage PIX1 of the pixel electrode 155 decreases to VP5, and the potential difference between the voltage VP5 and the voltage VCOM of the common electrode 156 is applied to the liquid crystal.

Next, negative polarity writing is performed during a period from time t14 to t16. That is, the scanning line drive circuit 30 supplies the first voltage as the selection voltage to the scanning line 110B, sets the voltage GATE1 of the scanning line 110B to VgH1, and turns on all the TFTs 151 of one horizontal line related to the scanning line 110B. To do.
At the same time, the image signal is supplied to the data line 120A at a voltage lower than the voltage VCOM of the common electrode 156 by the data line driving circuit 40, and the image data is written to the pixel electrode 155 via the conductive TFT 151. Then, the voltage PIX1 of the pixel electrode 155 becomes VP6, and the potential difference between the voltage VP6 and the voltage VCOM of the common electrode 156 is applied to the liquid crystal.

  Next, at time t16, the scanning line driving circuit 30 sets the voltage GATE1 of the scanning line 110A to VgL, and turns off all the TFTs 151 of one horizontal line related to the scanning line 110A. Then, when the TFT 151 changes from the semi-conducting state to the non-conducting state, the charges accumulated in the storage capacitor 153 and the charges accumulated in the pixel capacitor by the pixel electrode 155 and the common electrode 156 are parasitic capacitances Cgs, Cds. Redistribution including a pushdown occurs. Accordingly, the voltage PIX1 of the pixel electrode 155 decreases to VP10, and the potential difference between the voltage VP10 and the voltage VCOM of the common electrode 156 is applied to the liquid crystal.

FIG. 7 is a timing chart in the partial display mode of the electro-optical device 1A.
In FIG. 7, the potential difference between the voltage VP11 and the voltage VP12, the potential difference between the voltage VP12 and the voltage VP13, the potential difference between the voltage VP13 and the voltage VP14, the potential difference between the voltage VP14 and the voltage VP15, the potential difference between the voltage VP16 and the voltage VP17, The potential difference between VP17 and voltage VP18, the potential difference between voltage VP18 and voltage VP19, and the potential difference between voltage VP19 and voltage VP20 are the same.
Further, the selection period of one horizontal line in the partial display mode is three times the selection period of one horizontal line in the full screen display mode. Specifically, the period from time t21 to t22 in FIG. 7 is equal to twice the period from time t11 to t13 in FIG. 6, and the period from time t22 to t23 in FIG. 7 is equal to time t11 in FIG. To t13.

In FIG. 7, in order to facilitate understanding, writing is performed with the same gradation in both positive polarity writing and negative polarity writing.
In this partial display mode, the center voltage Vc of the image signal is equal to the voltage VCOM of the common electrode 156.

First, during the period from time t21 to t22, first positive polarity writing is performed. That is, the scanning line driving circuit 30 supplies the first voltage as the selection voltage to the scanning line 110A, sets the voltage GATE1 of the scanning line 110A to VgH1, and turns on all the TFTs 151 of one horizontal line related to the scanning line 110A. To do.
At the same time, the data line driving circuit 40 supplies an image signal to the data line 120A at a voltage higher than the voltage VCOM of the common electrode 156, and writes image data to the pixel electrode 155 via the conductive TFT 151. Then, the voltage PIX1 of the pixel electrode 155 becomes VP11, and the potential difference between the voltage VP11 and the voltage VCOM of the common electrode 156 is applied to the liquid crystal.

  Next, at time t22, the scanning line driving circuit 30 supplies the second voltage as the selection voltage to the scanning line 110A, the voltage GATE1 of the scanning line 110A is set to VgH2, and the TFT 151 of one horizontal line related to the scanning line 110A. Are all made semi-conductive. Then, when the TFT 151 changes from the conductive state to the semi-conductive state, the charges accumulated in the storage capacitor 153 and the charges accumulated in the pixel capacitor by the pixel electrode 155 and the common electrode 156 become the parasitic capacitances Cgs and Cds. Including redistribution, resulting in pushdown. Therefore, the voltage PIX1 of the pixel electrode 155 decreases to VP13, and a potential difference between the voltage VP13 and the voltage VCOM of the common electrode 156 is applied to the liquid crystal.

Next, second positive writing is performed during a period from time t22 to t23. That is, the scanning line driving circuit 30 supplies the second voltage as the selection voltage to the scanning line 110A, sets the voltage GATE1 of the scanning line 110A to VgH2, and all the TFTs 151 of one horizontal line related to the scanning line 110A are in a semi-conducting state. To.
At the same time, the data line driving circuit 40 supplies an image signal to the data line 120A at a voltage higher than the voltage VCOM of the common electrode 156, and writes the image data to the pixel electrode 155 via the TFT 151 in a semiconductive state. Then, the voltage PIX1 of the pixel electrode 155 recovers to become VP12 during a period in which the TFT 151 is in a semi-conducting state, and a potential difference between the voltage VP12 and the voltage VCOM of the common electrode 156 is applied to the liquid crystal.

  Next, at time t23, the scanning line driving circuit 30 sets the voltage GATE1 of the scanning line 110A to VgL, and turns off all the TFTs 151 of one horizontal line related to the scanning line 110A. Then, when the TFT 151 changes from the semi-conducting state to the non-conducting state, the charges accumulated in the storage capacitor 153 and the charges accumulated in the pixel capacitor by the pixel electrode 155 and the common electrode 156 are parasitic capacitances Cgs, Cds. Redistribution including a pushdown occurs. Accordingly, the voltage PIX1 of the pixel electrode 155 decreases to VP14, and a potential difference between the voltage VP14 and the voltage VCOM of the common electrode 156 is applied to the liquid crystal.

Next, first negative polarity writing is performed during a period from time t24 to t25. That is, the scanning line driving circuit 30 supplies a first voltage as a selection voltage to the scanning line 110B, sets the voltage GATE2 of the scanning line 110B to VgH1, and turns on all the TFTs 151 of one horizontal line related to the scanning line 110B. To do.
At the same time, the image signal is supplied to the data line 120A at a voltage lower than the voltage VCOM of the common electrode 156 by the data line driving circuit 40, and the image data is written to the pixel electrode 155 via the conductive TFT 151. Then, the voltage PIX1 of the pixel electrode 155 becomes VP16, and a potential difference between the voltage VP16 and the voltage VCOM of the common electrode 156 is applied to the liquid crystal.

  Next, at time t25, the scanning line driving circuit 30 supplies the second voltage as the selection voltage to the scanning line 110A, the voltage GATE1 of the scanning line 110A is set to VgH2, and the TFT 151 of one horizontal line related to the scanning line 110A. Are all made semi-conductive. Then, when the TFT 151 changes from the conductive state to the semi-conductive state, the charges accumulated in the storage capacitor 153 and the charges accumulated in the pixel capacitor by the pixel electrode 155 and the common electrode 156 become the parasitic capacitances Cgs and Cds. Including redistribution, resulting in pushdown. Accordingly, the voltage PIX1 of the pixel electrode 155 decreases to VP18, and a potential difference between the voltage VP18 and the voltage VCOM of the common electrode 156 is applied to the liquid crystal.

Next, the second negative writing is performed during the period from time t25 to t26. That is, the scanning line driving circuit 30 supplies the second voltage as the selection voltage to the scanning line 110A, sets the voltage GATE1 of the scanning line 110A to VgH2, and all the TFTs 151 of one horizontal line related to the scanning line 110A are in a semi-conducting state. To.
At the same time, the data line driving circuit 40 supplies an image signal to the data line 120A at a voltage lower than the voltage VCOM of the common electrode 156, and writes image data to the pixel electrode 155 via the TFT 151 in a semi-conducting state. Then, the voltage PIX1 of the pixel electrode 155 recovers to VP16 during a period in which the TFT 151 is in a semi-conducting state, and a potential difference between the voltage VP16 and the voltage VCOM of the common electrode 156 is applied to the liquid crystal.

  Next, at time t26, the scanning line driving circuit 30 sets the voltage GATE1 of the scanning line 110A to VgL, and turns off all the TFTs 151 of one horizontal line related to the scanning line 110A. Then, when the TFT 151 changes from the semi-conductive state to the non-conductive state, the charges accumulated in the storage capacitor 153 and the charges accumulated in the pixel capacitor by the pixel electrode 155 and the common electrode 156 are parasitic capacitances Cgs, Cds. Redistribution including a pushdown occurs. Accordingly, the voltage PIX1 of the pixel electrode 155 decreases to VP18, and a potential difference between the voltage VP18 and the voltage VCOM of the common electrode 156 is applied to the liquid crystal.

According to this embodiment, there are the following effects.
(2) In the partial display mode, the electro-optical device 1A supplies the first voltage as a selection voltage in the period from time t21 to t22 in FIG. 7 by the scanning line driving circuit 30, and from this time t21 to t22. After the period ends, a second voltage lower than the first voltage is supplied during a period from time t22 to t23. That is, in a state where the first voltage is applied to the switching element, the TFT 151 becomes conductive, and image data based on an image signal is written to the pixel electrode 155. On the other hand, in a state where the second voltage is applied to the TFT 151, the TFT 151 is in a semi-conductive state between the conductive state and the non-conductive state. In this case, when the state changes from the conductive state to the semiconductive state, that is, at time t22, pushdown occurs, and the voltage PIX1 of the pixel electrode 155 decreases from VP11 to VP13. However, the voltage PIX1 of the pixel electrode 155 can be recovered from VP13 to VP12 during a period from time t22 to t23 when the TFT 151 is in a semi-conducting state.
Further, in the partial display mode, the electro-optical device 1A supplies the first voltage as a selection voltage in the period from time t24 to t25 in FIG. 7 by the scanning line driving circuit 30, and from time t24 to t25. After the period ends, a second voltage lower than the first voltage is supplied in a period from time t25 to t26. Then, similarly to the above-described time t22, at time t25 when the TFT 151 changes from the conductive state to the semi-conductive state, pushdown occurs, and the voltage PIX1 of the pixel electrode 155 decreases from VP16 to VP18. However, the voltage PIX1 of the pixel electrode 155 can be recovered from VP18 to VP16 during the period from time t25 to t26 when the TFT 151 is in a semi-conducting state, as in the period from time t22 to t23.
Accordingly, since the final pushdown voltage in the partial display mode can be reduced, flicker and burn-in in the display area can be reduced.

  (3) In the electro-optical device 1, the data line 120 is supplied at a voltage higher than the voltage of the common electrode 156 by the data line driving circuit 40 while supplying the selection voltage to the scanning lines 110 in a line sequential manner by the scanning line driving circuit 30. The positive polarity writing for supplying the image signal to the negative electrode and the negative polarity writing for supplying the image signal to the data line 120 at a voltage lower than the voltage of the common electrode 156 were alternately performed. Therefore, since the polarity of the voltage applied to the liquid crystal can be reversed, it is possible to further reduce the burn-in of the display area by changing the alignment of the liquid crystal every predetermined period.

(4) In the full-screen display mode, the electro-optical device 1 is applied to the common electrode 156 by the data line driving circuit 40 while supplying the selection voltage to the scanning lines 110 line-sequentially by the scanning line driving circuit 30. Positive and negative image signals were alternately supplied to the data line 120 with reference to a voltage higher than the voltage by the final pushdown voltage. That is, since the center voltage Vc of the image signal is made higher than the voltage VCOM of the common electrode 156 by the final pushdown voltage, flicker and burn-in in the display area can be reduced in the full screen display mode.
On the other hand, in the partial display mode, the electro-optical device 1 supplies the selection voltage to the scanning line 110 line-sequentially by the scanning line driving circuit 30 and uses the data line driving circuit 40 with the voltage VCOM of the common electrode 156 as a reference. Positive and negative image signals were alternately supplied to the data line 120. That is, since the voltage VCOM of the common electrode 156 and the voltage of the image signal in the non-display area are the same, the power consumption can be reduced in the partial display mode.

<Third Embodiment>
FIG. 8 is a block diagram showing a configuration of an electro-optical device 1B according to the third embodiment of the present invention.
The electro-optical device 1B is different from the electro-optical device 1A of FIG. 4 in that the liquid crystal driving power supply circuit 50A includes a charge pump circuit 51.

  FIG. 9 is a circuit diagram of the charge pump circuit 51. The charge pump circuit 51 is provided in the liquid crystal driving power supply circuit 50 </ b> A, and includes a first charge pump unit circuit 511 and a second charge pump unit circuit 512.

  The first charge pump unit circuit 511 includes input terminals A and B and an output terminal C. The first charge pump unit circuit 511 adds the potential difference between the input terminals A and B to the voltage at the input terminal A and outputs the voltage from the output terminal C. That is, the first charge pump unit circuit 511 substantially doubles the voltage at the input terminal A and outputs it from the output terminal C.

  Specifically, the first charge pump unit circuit 511 includes a capacitor 531, a switching element 532 that connects one end of the capacitor 531 to the input terminal A or the output terminal C, and the other end of the capacitor 531 as an input terminal. A switching element 533 connected to A or the input terminal B, and a capacitor 534 having one end connected to the input terminal A and the other end connected to the output terminal C.

  The switching elements 532 and 533 are switched in conjunction with each other. That is, when the switching element 532 connects one end side of the capacitor 531 to the input terminal A, the switching element 533 connects the other end side of the capacitor 531 to the input terminal B. On the other hand, when the switching element 532 connects one end side of the capacitor 531 to the output terminal C, the switching element 533 connects the other end side of the capacitor 531 to the input terminal A.

First, the switching element 532 connects one end side of the capacitor 531 to the input terminal A, and the switching element 533 connects the other end side of the capacitor 531 to the input terminal B. In this state, the digital input voltage VDD is supplied to the input terminal A and the digital GND is supplied to the input terminal B.
Then, the capacitor 531 is charged with the digital voltage VDD.

Next, the switching elements 532 and 533 are respectively switched so that the switching element 532 connects one end side of the capacitor 531 to the output terminal C, and the switching element 533 connects the other end side of the capacitor 531 to the input terminal A.
Then, the capacitor 534 is charged with a digital voltage 2VDD that is the sum of the digital voltage VDD charged in the capacitor 531 and the digital input voltage VDD supplied from the input terminal A.

  As described above, the first charge pump unit circuit 511 boosts the digital input voltage VDD to the digital voltage 2VDD that is approximately double. The digital voltage 2VDD is output from the output terminal C and supplied to the second charge pump unit circuit 512.

The second charge pump unit circuit 512 has the same configuration as that of the first charge pump unit circuit 511. That is, input terminals B and C and an output terminal D are provided. The second charge pump unit circuit 512 adds the potential difference between the input terminals B and C to the voltage of the input terminal C, and outputs it from the output terminal D.
Since the digital voltage 2VDD is supplied to the input terminal C, the second charge pump unit circuit 512 substantially doubles the digital voltage 2VDD supplied from the first charge pump unit circuit 511, that is, the digital input voltage VDD. Is boosted to a digital voltage 4VDD that is approximately four times as high as the output voltage from the output terminal D.

In the electro-optical device 1B including the above-described charge pump circuit 51, for example, the first voltage that makes the TFT 151 conductive is 16V, and the second voltage that makes the TFT 151 semi-conductive is 8V.
In order to generate these voltages of 8V and 16V, a digital input voltage of 4V is supplied from the input terminal A to the charge pump circuit 51, and a digital GND of 0V is supplied from the input terminal B.
Then, the charge pump circuit 51 boosts the 4V digital input voltage supplied from the input terminal A to 16V, which is approximately four times, and outputs the boosted voltage from the output terminal D. The voltage at the output terminal D is used as the first voltage.
The charge pump circuit 51 boosts the 4V digital input voltage supplied from the input terminal A to 8V, which is approximately doubled, and outputs it from the output terminal C. The voltage at the output terminal C is used as the second voltage.

  As described above, the charge pump circuit 51 generates the first voltage that makes the TFT 151 conductive, and the second voltage that makes the TFT 151 semiconductive.

According to this embodiment, there are the following effects.
(5) The charge pump circuit 51 generates a first voltage that makes the TFT 151 conductive, and a second voltage that makes the TFT 151 semiconductive. Therefore, if there is one liquid crystal driving power supply circuit having the charge pump circuit 51, the scanning line driving circuit 30 can supply the selection voltage of the first voltage and the second voltage to the scanning line 110. Therefore, compared with the case where two liquid crystal driving power supply circuits for generating the first voltage and a liquid crystal driving power supply circuit for generating the second voltage are required, the circuit scale and power consumption May be reduced.

<Fourth embodiment>
FIG. 10 is a block diagram showing a configuration of an electro-optical device 1C according to the fourth embodiment of the present invention.
The electro-optical device 1C is different from the electro-optical device 1A in FIG. 4 in that the scanning line driving circuit 30A can adjust the potential of the second voltage and the period during which the second voltage is supplied.

  The scanning line driving circuit 30A adjusts the potential of the second voltage supplied to the scanning line 110 according to the polarity of positive polarity writing or negative polarity writing. Specifically, the scanning line driving circuit 30A adjusts the second voltage in negative polarity writing to a potential lower than the second voltage in positive polarity writing.

  In addition, the scanning line driving circuit 30A adjusts the period during which the second voltage is supplied according to the polarity of positive polarity writing or negative polarity writing. Specifically, the scanning line driving circuit 30A makes the period for supplying the second voltage in the negative polarity writing shorter than the period for supplying the second voltage in the positive polarity writing.

FIG. 11 is a timing chart in the partial display mode of the electro-optical device 1C.
For comparison with the electro-optical device 1A in the partial display mode, the selection period of one horizontal line at the time of positive writing of the electro-optical device 1C in the partial display mode is the positive polarity book of the electro-optical device 1A in the partial display mode. It is equal to the selection period of one horizontal line at the time of loading. Specifically, the period from time t31 to t32 in FIG. 11 is equal to the period from time t21 to t22 in FIG. Further, the period from time t32 to t33 in FIG. 11 is equal to the period from time t22 to t23 in FIG.
On the other hand, the selection period of one horizontal line at the time of negative writing of the electro-optical device 1C in the partial display mode is different from the selection period of one horizontal line at the time of negative writing of the electro-optical device 1A in the partial display mode. ing. Specifically, the period from time t34 to t35 in FIG. 11 is equal to the period from time t24 to t25 in FIG. 7, but the period from time t35 to t36 in FIG. The period is half of the period from t25 to t26.
In FIG. 11, in order to facilitate understanding, writing is performed with the same gradation in both positive polarity writing and negative polarity writing.

First, during the period from time t31 to t32, first positive polarity writing is performed. That is, the scanning line driving circuit 30 supplies the first voltage as the selection voltage to the scanning line 110A, sets the voltage GATE1 of the scanning line 110A to VgH1, and turns on all the TFTs 151 of one horizontal line related to the scanning line 110A. To do.
At the same time, the data line driving circuit 40 supplies an image signal to the data line 120A at a voltage higher than the voltage VCOM of the common electrode 156, and writes image data to the pixel electrode 155 via the conductive TFT 151. Then, the voltage PIX1 of the pixel electrode 155 becomes VP11, and the potential difference between the voltage VP11 and the voltage VCOM of the common electrode 156 is applied to the liquid crystal.

  Next, at time t32, the scanning line driving circuit 30 supplies the second voltage as the selection voltage to the scanning line 110A, the voltage GATE1 of the scanning line 110A is set to VgH2, and the TFT 151 of one horizontal line related to the scanning line 110A. Are all made semi-conductive. Then, when the TFT 151 changes from the conductive state to the semi-conductive state, the charges accumulated in the storage capacitor 153 and the charges accumulated in the pixel capacitor by the pixel electrode 155 and the common electrode 156 become the parasitic capacitances Cgs and Cds. Including redistribution, resulting in pushdown. Therefore, the voltage PIX1 of the pixel electrode 155 decreases to VP13, and a potential difference between the voltage VP13 and the voltage VCOM of the common electrode 156 is applied to the liquid crystal.

Next, second positive writing is performed during a period from time t32 to t33. That is, the scanning line driving circuit 30 supplies the second voltage as the selection voltage to the scanning line 110A, sets the voltage GATE1 of the scanning line 110A to VgH2, and all the TFTs 151 of one horizontal line related to the scanning line 110A are in a semi-conducting state. To.
At the same time, the data line driving circuit 40 supplies an image signal to the data line 120A at a voltage higher than the voltage VCOM of the common electrode 156, and writes the image data to the pixel electrode 155 via the TFT 151 in a semiconductive state. Then, the voltage PIX1 of the pixel electrode 155 recovers to become VP12 during a period in which the TFT 151 is in a semi-conducting state, and a potential difference between the voltage VP12 and the voltage VCOM of the common electrode 156 is applied to the liquid crystal.

  Next, at time t33, the scanning line driving circuit 30 sets the voltage GATE1 of the scanning line 110A to VgL, and turns off all the TFTs 151 of one horizontal line related to the scanning line 110A. Then, when the TFT 151 changes from the semi-conducting state to the non-conducting state, the charges accumulated in the storage capacitor 153 and the charges accumulated in the pixel capacitor by the pixel electrode 155 and the common electrode 156 are parasitic capacitances Cgs, Cds. Redistribution including a pushdown occurs. Accordingly, the voltage PIX1 of the pixel electrode 155 decreases to VP14, and a potential difference between the voltage VP14 and the voltage VCOM of the common electrode 156 is applied to the liquid crystal.

Next, first negative polarity writing is performed during a period from time t34 to t35. That is, the scanning line driving circuit 30 supplies the first voltage as the selection voltage to the scanning line 110A, sets the voltage GATE1 of the scanning line 110A to VgH1, and turns on all the TFTs 151 of one horizontal line related to the scanning line 110A. To do.
At the same time, the image signal is supplied to the data line 120A at a voltage lower than the voltage VCOM of the common electrode 156 by the data line driving circuit 40, and the image data is written to the pixel electrode 155 via the conductive TFT 151. Then, the voltage PIX1 of the pixel electrode 155 becomes VP16, and a potential difference between the voltage VP16 and the voltage VCOM of the common electrode 156 is applied to the liquid crystal.

  Next, at time t35, the scanning line driving circuit 30 supplies the scanning line 110A with the voltage of the above-mentioned second voltage lowered as the selection voltage, so that the voltage GATE1 of the scanning line 110A is lower than VgH2 and has positive polarity. VgH3 higher than the image signal DATA1 in writing is set, and all the TFTs 151 of one horizontal line related to the scanning line 110A are set in a semiconductive state. Then, when the TFT 151 changes from the conductive state to the semi-conductive state, the charges accumulated in the storage capacitor 153 and the charges accumulated in the pixel capacitor by the pixel electrode 155 and the common electrode 156 become the parasitic capacitances Cgs and Cds. Including redistribution, resulting in pushdown. Accordingly, the voltage PIX1 of the pixel electrode 155 decreases to VP18, and a potential difference between the voltage VP18 and the voltage VCOM of the common electrode 156 is applied to the liquid crystal.

Next, the second negative writing is performed during the period from time t35 to t36, which is a half of the period from time t32 to t33. That is, the scanning line driving circuit 30 supplies the selection voltage with the second voltage lowered to the scanning line 110A, the voltage GATE1 of the scanning line 110A is set to VgH3, and one horizontal line related to the scanning line 110A All TFTs 151 are brought into a semiconductive state.
At the same time, the data line driving circuit 40 supplies an image signal to the data line 120A at a voltage higher than the voltage VCOM of the common electrode 156, and writes the image data to the pixel electrode 155 via the TFT 151 in a semiconductive state. Then, the voltage PIX1 of the pixel electrode 155 recovers to VP17 during a period in which the TFT 151 is in a semi-conducting state, and a potential difference between the voltage VP17 and the voltage VCOM of the common electrode 156 is applied to the liquid crystal.

  Next, at time t36, the scanning line driving circuit 30 sets the voltage GATE1 of the scanning line 110A to VgL, and turns off all the TFTs 151 of one horizontal line related to the scanning line 110A. Then, when the TFT 151 changes from the semi-conducting state to the non-conducting state, the charges accumulated in the storage capacitor 153 and the charges accumulated in the pixel capacitor by the pixel electrode 155 and the common electrode 156 are parasitic capacitances Cgs, Cds. Redistribution including a pushdown occurs. Accordingly, the voltage PIX1 of the pixel electrode 155 decreases to VP19, and a potential difference between the voltage VP19 and the voltage VCOM of the common electrode 156 is applied to the liquid crystal.

According to this embodiment, there are the following effects.
(6) Depending on the characteristics of the TFT 151, the potential at which the voltage PIX1 of the pixel electrode 155 recovers may be different between the case of performing the second positive writing and the case of performing the second negative writing (FIG. 7).
In the electro-optical device 1 </ b> C, the second voltage in negative writing is adjusted to a potential lower than the second voltage in positive writing by the scanning line driving circuit 30 </ b> A. As a result, the level of the semiconducting state of the TFT 151 by the second voltage can be adjusted, and the potential at which the voltage PIX1 of the pixel electrode 155 recovers in the second negative writing can be changed. Therefore, the pushdown voltage in negative polarity writing can be reduced.

  (7) In the electro-optical device 1 </ b> C, the period for supplying the second voltage to the scanning line in the negative polarity writing is made half of the period for supplying the second voltage in the positive polarity writing by the scanning line driving circuit 30 </ b> A. This adjusts the balance between the conductive state of the TFT 151 by the first voltage and the semiconductive state of the TFT 151 by the second voltage, and changes the potential at which the voltage PIX1 of the pixel electrode 155 recovers in the second negative writing. Can be made. Therefore, the pushdown voltage in negative polarity writing can be reduced.

<Modification>
It should be noted that the present invention is not limited to the above-described embodiment, and modifications, improvements, etc. within a scope that can achieve the object of the present invention are included in the present invention.
For example, in each of the embodiments described above, the charge pump circuit 51 can output a digital voltage up to about four times the digital input voltage. However, the present invention is not limited to this, and for example, outputs a digital voltage up to about eight times. It may be possible.

  In this embodiment, the data line driving circuit 40 is driven by the 1H inversion driving method. However, the data line driving circuit 40 is not limited to this. For example, the positive polarity writing or the alternating writing is performed for each pixel using an AC voltage. It may be driven by a dot inversion driving method for performing negative polarity writing.

  Further, for example, in each of the above-described embodiments, the present invention is applied to the electro-optical device 1 using liquid crystal. However, the present invention is not limited to this, and can also be applied to an electro-optical device using an electro-optical material other than liquid crystal. An electro-optical material is a material whose optical characteristics such as transmittance and luminance change when an electric signal (current signal or voltage signal) is supplied. For example, a display panel using an OLED element such as an organic EL (Electro-Luminescent) or a light emitting polymer as an electro-optical material, or a microcapsule containing a colored liquid and white particles dispersed in the liquid is used as the electro-optical material. The electrophoretic display panel used as a twist ball display panel using a twist ball painted differently for each region of different polarity as an electro-optical material, a toner display panel using black toner as an electro-optical material, or The present invention can also be applied to various electro-optical devices such as a plasma display panel using a high-pressure gas such as helium or neon as an electro-optical material.

<Application example>
Next, an electronic apparatus to which the electro-optical device 1 according to the above-described embodiment is applied will be described.
FIG. 12 is a perspective view illustrating a configuration of a mobile phone to which the electro-optical device 1 is applied. The cellular phone 3000 includes a plurality of operation buttons 3001, scroll buttons 3002, and the electro-optical device 1. By operating the scroll button 3002, the screen displayed on the electro-optical device 1 is scrolled.

  Note that electronic devices to which the electro-optical device 1 is applied include those shown in FIG. 12, personal computers, portable information terminals, digital still cameras, liquid crystal televisions, viewfinder type, monitor direct view type video tape recorders, car navigation systems. Examples of the apparatus include a device, a pager, an electronic notebook, a calculator, a word processor, a workstation, a video phone, a POS terminal, and a touch panel. The electro-optical device described above can be applied as a display unit of these various electronic devices.

1 is a block diagram illustrating a configuration of an electro-optical device according to a first embodiment of the invention. FIG. FIG. 3 is a partially enlarged plan view of a liquid crystal panel of the electro-optical device. 3 is a timing chart of the electro-optical device. FIG. 6 is a block diagram illustrating a configuration of an electro-optical device according to a second embodiment of the invention. FIG. 3 is a diagram showing a display screen of a liquid crystal panel in a partial display mode of the electro-optical device. 4 is a timing chart in a full screen display mode of the electro-optical device. 6 is a timing chart in a partial display mode of the electro-optical device. FIG. 10 is a block diagram illustrating a configuration of an electro-optical device according to a third embodiment of the invention. FIG. 3 is a circuit diagram of a charge pump circuit of the electro-optical device. FIG. 10 is a block diagram illustrating a configuration of an electro-optical device according to a fourth embodiment of the invention. 6 is a timing chart in a partial display mode of the electro-optical device. It is a perspective view which shows the structure of the mobile telephone to which the said electro-optical apparatus is applied.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1, 1A, 1B, 1C ... Electro-optical device, 30, 30A ... Scanning line drive circuit, 40 ... Data line drive circuit, 50, 50A ... Liquid crystal drive power supply circuit (power supply circuit), 51 ... Charge pump circuit, 110, 110A, 110B, 110C ... scanning lines, 120, 120A, 120B ... data lines, 150 ... pixels, 151 ... TFTs (switching elements), 155 ... pixel electrodes, 156 ... common electrodes, 3000 ... mobile phones (electronic devices).

Claims (10)

An electro-optical device comprising a plurality of scanning lines, a plurality of data lines, and a plurality of pixels provided corresponding to intersections of the scanning lines and the data lines,
The pixel includes a pixel electrode, a common electrode facing the pixel electrode, and a switching element that brings the data line and the pixel electrode into a conductive state when a selection voltage is applied to the scanning line. ,
A scanning line driving circuit for supplying the selection voltage for selecting the scanning lines in a predetermined order;
A data line driving circuit for supplying an image signal to the data line when the scanning line is selected;
The scanning line driving circuit supplies a first voltage as the selection voltage in the first period, and lowers the image signal lower than the first voltage in a predetermined second period from the end of the first period. An electro-optical device that supplies a second voltage higher than an amplitude. The electro-optical device according to claim 1.
The electro-optical device, wherein the scanning line driving circuit adjusts the potential of the second voltage. The electro-optical device according to claim 1,
The electro-optical device, wherein the scanning line driving circuit adjusts the second period. A plurality of scanning lines, a plurality of data lines, and a plurality of pixels provided corresponding to intersections of the scanning lines and the data lines, and a full screen display mode for displaying a full screen; An electro-optical device capable of selecting a partial display mode in which a partial area on the screen is a display area and another area is a non-display area,
The pixel includes a pixel electrode, a common electrode facing the pixel electrode, and a switching element that brings the data line and the pixel electrode into a conductive state when a selection voltage is applied to the scanning line. ,
A scanning line driving circuit for supplying the selection voltage for selecting the scanning lines in a predetermined order;
A data line driving circuit for supplying an image signal to the data line when the scanning line is selected;
The scanning line driving circuit supplies, as the selection voltage, a first voltage in the full-screen display mode, a first voltage in the first display period in the partial display mode, and an end of the first period. An electro-optical device, wherein a second voltage lower than the first voltage is supplied during a predetermined second period. The electro-optical device according to claim 4.
The data line driving circuit is configured to apply positive writing for supplying an image signal to the data line at a voltage higher than a voltage applied to the common electrode when the scanning line is selected, and to apply to the common electrode An electro-optical device that alternately performs negative polarity writing for supplying an image signal to the data line at a voltage lower than the applied voltage. The electro-optical device according to claim 5.
In the full screen display mode, the data line driving circuit alternately supplies positive and negative image signals to the data line with reference to a predetermined voltage higher than the voltage applied to the common electrode. In addition, in the partial display mode, the data line driving circuit alternately supplies positive and negative image signals to the data lines with reference to a voltage applied to the common electrode. An electro-optical device. The electro-optical device according to any one of claims 4 to 6,
The electro-optical device, wherein the scanning line driving circuit adjusts the potential of the second voltage in a range larger than the amplitude of the image signal. The electro-optical device according to any one of claims 4 to 7,
The electro-optical device, wherein the scanning line driving circuit adjusts the second period. The electro-optical device according to any one of claims 1 to 8,
A power supply circuit for generating the first voltage and the second voltage;
The electro-optical device, wherein the power supply circuit includes a charge pump circuit that boosts an input voltage to generate the first voltage and the second voltage.   An electronic apparatus comprising the electro-optical device according to claim 1.

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