JP4423925B2 - ELECTRO-OPTICAL DEVICE, DEVICE AND METHOD FOR CONTROLLING THE SAME, AND ELECTRONIC DEVICE - Google Patents

Description

The present invention relates to a technique for displaying an image using an electro-optic material that converts an electrical action such as current supply or voltage application into an optical action such as a change in transmittance or luminance.

Various electro-optical devices that display an image using an electro-optical material have been proposed. For example, a liquid crystal device using liquid crystal as an electro-optical material includes a plurality of pixel electrodes that are electrically connected to scanning lines and data lines through switching elements, and a pixel electrode that faces the pixel electrodes with the electro-optical material interposed therebetween. Electrode. Under this configuration, when a switching element is turned on by selecting a scanning line, various images are displayed by applying a voltage corresponding to the image to the data line.

In this type of electro-optical device, charges may remain in each pixel electrode and the counter electrode even after the image display is finished. Such residual charges (hereinafter sometimes referred to as “residual charges”) cause various problems. For example, the direct current voltage due to the residual charge continues to be applied to the liquid crystal even after power supply to the electro-optical device is stopped, so that the orientation direction of the liquid crystal changes in a direction different from the intended direction, thereby improving the display quality. A decline is caused. Also, assuming that charges remain on each electrode at the stage of starting image display, the voltage actually applied to the liquid crystal during image display is the amount corresponding to the residual charge. Therefore, an image caused by residual charge (that is, an image displayed immediately before the power is turned off last time) is superimposed on the displayed image and appears as an afterimage. As a technique for solving these problems, various techniques for removing residual charges by setting the pixel electrode and the counter electrode to the same voltage when the image display is finished have been proposed (for example, Patent Document 1). reference).

JP 2001-147416 A (paragraph 0065)

However, even if this type of technique is used, there is a problem that the residual charges cannot always be completely removed as shown below. That is, when the power supply to each driving circuit (scanning line driving circuit or data line driving circuit) is stopped after setting the pixel electrode and the counter electrode to the same voltage, the voltage of each part fluctuates instantaneously with the stop, Due to this variation, a voltage may be applied between the pixel electrode and the counter electrode. In such a case, charges remain on the pixel electrode and the counter electrode, and a DC voltage is continuously applied to the electro-optical material. The present invention has been made in view of such circumstances, and an object of the present invention is to sufficiently remove the charge accumulated in each electrode in accordance with display of an image, thereby causing deterioration and display of the electro-optical material. The purpose is to prevent various problems caused by residual charges, such as deterioration of quality.

The present invention provides a plurality of pixel electrodes electrically connected to the scanning lines and the data lines via switching elements provided at the intersections of the plurality of scanning lines and the plurality of data lines, and a plurality of the electrodes with the electro-optic material interposed therebetween. A counter electrode facing the pixel electrode, a scanning line driving circuit that sequentially selects each of the plurality of scanning lines and turns on a switching element corresponding to the scanning line, and is turned on by the scanning line driving circuit The electro-optical device includes a data line and a data line driving circuit that supplies an image signal to the pixel electrode connected to the switching element via the switching element.

In order to solve the above-described problems in this type of electro-optical device, the first feature of the present invention is that it is opposed to the voltage of the image signal supplied to the pixel electrode when a display stop signal instructing to stop display is input. After the voltage applied to the electrodes is changed to substantially the same voltage, and the voltage of the image signal and the voltage applied to the counter electrode are made substantially the same voltage, selection by the scanning line driving circuit is performed for all the scanning lines. Thus, the operations of the scanning line driving circuit and the data line driving circuit are stopped, and after the operations of the scanning line driving circuit and the data line driving circuit are stopped, the power supply to these driving circuits is stopped. According to the present invention, since the voltage of the image signal supplied to the pixel electrode and the voltage applied to the counter electrode are set to substantially the same voltage, selection by the scanning line driving circuit is executed for all the scanning lines. Electric charges accumulated in each pixel electrode and counter electrode can be effectively removed. In addition, since the power supply to each drive circuit is stopped after the operation of the scanning line drive circuit and the data line drive circuit is stopped, no voltage is suddenly applied to each pixel electrode when the power supply is stopped. . Therefore, the electric charge accumulated in each electrode is surely removed, and the electro-optic material is deteriorated (
In addition, various problems caused by the residual charges such as deterioration of display quality due to deterioration of the electro-optical material can be prevented.

In order to solve the above problems, the second feature of the present invention is that when a display start signal instructing the start of display is input, the voltage of the image signal supplied to the pixel electrode and the application to the counter electrode After the selection by the scanning line driving circuit is performed for all scanning lines in a state where the voltage is substantially the same voltage, the operations of the scanning line driving circuit and the data line driving circuit are stopped, and the scanning line driving circuit and the data are After the operation of the line drive circuit is stopped, the voltage applied to the counter electrode is changed toward a predetermined value, and after the voltage applied to the counter electrode reaches the predetermined value, the operation of the scanning line drive circuit and the data line drive circuit Is to start. According to the present invention, since selection by the scanning line driving circuit is performed for all scanning lines in a state where the voltage of the image signal and the voltage applied to the counter electrode are substantially the same voltage, each pixel electrode and counter electrode The charges accumulated in the image can be effectively removed prior to image display. Moreover, after the operations of the scanning line driving circuit and the data line driving circuit are once stopped, the applied voltage to the counter electrode is changed toward a predetermined value, and after reaching the predetermined value, the scanning line driving circuit and the data line driving are performed. Since the operation of the circuit is started, no voltage is suddenly applied to each pixel electrode when a voltage is applied to the counter electrode accompanying the start of power feeding. Therefore, various problems caused by the residual charge such as a decrease in display quality immediately after image display is started can be prevented.

The electro-optical material in the present invention means various materials whose optical action changes according to an electric signal. However, the present invention is particularly applicable to an electro-optical device using an electro-optical material (that is, it is desirable to avoid applying a DC voltage to the electro-optical material) in which deterioration of characteristics due to residual charges is a problem. Is preferred. A typical example of such an electro-optical material is liquid crystal, but the present invention can be applied to other electro-optical materials. Also, “change the voltage of the image signal and the voltage applied to the counter electrode to substantially the same voltage”
This means that the voltage of the image signal and the voltage applied to the counter electrode approach or match so that the charge accumulated on both electrodes is removed to the extent that it does not cause degradation of the electro-optic material. It does not necessarily have to match in meaning. In a desirable mode of the present invention, both the voltage of the image signal and the voltage applied to the counter electrode are changed substantially simultaneously to the lower side of the power supply voltage.
But the voltage value after a change is not restricted to this.

The present invention can also be specified as a device that controls the electro-optical device according to the procedure according to the first or second feature, or as an electro-optical device including the control device. Furthermore, according to the electronic apparatus including the electro-optical device according to the present invention, it is possible to prevent the display quality from being deteriorated due to the residual charge and to realize a high-quality display. As an electronic apparatus according to the present invention, for example, a projector using the electro-optical device according to the present invention as a light valve (means for modulating light to be irradiated on a screen according to a display image), or the electric apparatus according to the present invention. There are various electronic devices such as an information processing apparatus such as a personal computer using an optical device as a display device.

The specific form which implemented this invention is demonstrated referring drawings. In the following, a mode in which the present invention is applied to a liquid crystal device using liquid crystal as an electro-optical material will be exemplified, but the scope to which the present invention can be applied is not limited to this device. Further, in the respective drawings shown below, the dimensions and ratios of the respective constituent elements are appropriately changed from the actual ones in order to make the respective constituent elements large enough to be recognized on the drawings.

FIG. 1 is a block diagram showing an electrical configuration of the liquid crystal device according to the present embodiment. As shown in the figure, the liquid crystal device 100 includes a control device 1, a processing circuit 2, a power supply circuit 3, and a liquid crystal panel 4. Among these, the control device 1 receives control signals (for example, a vertical scanning signal, a horizontal scanning signal, and a dot clock signal) supplied from various host devices such as a CPU (Central Processing Unit) of an electronic device in which the liquid crystal device 100 is mounted. Based on the liquid crystal device 10
This is a device for generating a signal for controlling each part of 0. Details of the control device 1 will be described later.

The processing circuit 2 is a circuit for processing the image signal V supplied from the host device into a signal suitable for supply to the liquid crystal panel 4, and includes a D / A (Digital to Analog) converter 21, S / P ( Ser
ial to parallel) conversion circuit 22 and amplification / inversion circuit 23. Of these, D / A
The converter 21 converts the digital image signal V supplied from the host device into an analog image signal V. Further, when an analog image signal V is input, the S / P conversion circuit 22 distributes the analog image signal V to N (N = 6 in this embodiment) system as shown in FIG. This is a circuit that expands the signal of each system by N times (serial-parallel conversion) in the time axis direction and outputs it. On the other hand, the amplifying / inverting circuit 23 inverts a signal that requires polarity inversion from the serial-parallel converted image signal V and amplifies each image signal V as appropriate, and then converts the image signal VID1 to VID6 into liquid crystal. A circuit for outputting to the panel 4. Here, the polarity reversal is based on a predetermined voltage Vc (a voltage that is the center of the amplitude of the image signals VID1 to VID6 and is substantially equal to a voltage LCcom applied to a counter electrode described later in this embodiment). The voltage levels of the image signals VID1 to VID6 are alternately switched from one of positive polarity and negative polarity to the other. For the image signal to be subjected to polarity inversion, the method of applying a voltage to each pixel is (1) a method of inverting the polarity for each scanning line 411 (so-called row inversion), or (2) for each data line 412. The method is appropriately selected depending on whether the polarity is inverted (so-called column inversion) or (3) the polarity is inverted for each adjacent pixel (so-called pixel inversion), and the inversion period is one horizontal scan. Set to period or dot clock period. In the present embodiment, it is assumed that a method of inverting the polarity for each scanning line 411 as in (1) above is employed. In the following, the image signals VID1 to VID
When it is not necessary to specify any of ID6, it is simply expressed as “image signal VID”. Further, here, the configuration in which the D / A conversion processing is performed prior to the S / P conversion processing and the amplification / inversion processing is illustrated, but a configuration in which the D / A conversion processing is performed after these processing may be employed. On the other hand, the power supply circuit 3 includes a control device 1 and a processing circuit 2, a scanning line driving circuit 61 and a data line driving circuit 6 described later.
3 for each part of the liquid crystal device 100, such as the high-order side and the low-order side of the power supply voltage (hereinafter, “
This circuit supplies a “higher power supply voltage” and a “lower power supply voltage”.

Next, the configuration of the liquid crystal panel 4 will be described with reference to FIGS. 2 and 3 (sectional view taken along line III-III in FIG. 2). As shown in these drawings, the liquid crystal panel 4 includes an element substrate 41 and a counter substrate 42 arranged so as to face each other via a sealing material 45 formed in a substantially rectangular frame shape. The element substrate 41 and the counter substrate 42 are plate-like or film-like members made of glass or plastic. For example, a TN (Twisted Nematic) type liquid crystal 46 is sealed as an electro-optical material in a space surrounded by both substrates and the sealing material 45.

A data line driving circuit 63 and a sampling circuit 64 are formed along one side of the sealing material 45 extending in the X direction on the plate surface of the element substrate 41 facing the counter substrate 42.
Further, a plurality of connection terminals 68 are formed in the vicinity of the peripheral edge of the element substrate 41 close to the data line driving circuit 63. One end of a flexible wiring board (not shown) is joined in the vicinity of the peripheral edge, and the wiring is connected to each connection terminal 68. The other end of the flexible printed circuit board is joined to a printed circuit board (not shown) on which the control device 1, the processing circuit 2 and the power supply circuit 3 are mounted, and each part on the printed circuit board and each part of the liquid crystal panel 4 Electrical continuity is achieved. Further, scanning line driving circuits 61 are respectively formed in regions along the two sides of the element substrate 41 extending in the Y direction, and the scanning lines extending in the X direction are driven from both sides. . Of course, if the delay of the scanning signal supplied to the scanning line is not a problem, a configuration in which only one scanning line driving circuit 61 is provided may be employed.

On the other hand, a counter electrode 421 is provided on a plate surface of the counter substrate 42 that faces the element substrate 41. The counter electrode 421 is electrically connected to the connection terminal 68 of the element substrate 41 by a conductive material (not shown) provided in at least one of the four corners of the counter substrate 42. Under this configuration, the counter electrode 421 is connected to the voltage L from the control device 1 via the connection terminal 68 and the conductive material.
Ccom is applied. Furthermore, the counter substrate 42 is provided so as to correspond to each pixel and is provided so as to overlap a region other than the pixel, such as a colored layer (color filter) that selectively transmits light of a specific wavelength, and blocks light. A light shielding layer is provided (both not shown). However, when used to modulate light having a wavelength corresponding to a specific color as in a projector described later (see FIG. 10), a colored layer is not necessary. In addition, while an alignment film is formed on the plate surface of each of the element substrate 41 and the counter substrate 42 on which the electrodes are formed, a polarizer is attached on the opposite plate surface. The illustration and description are omitted because they are not directly related.

Next, with reference to FIG. 4, the electrical configuration of each element provided on the element substrate 41 will be described.
As shown in the figure, a region (so-called display region) used for displaying an image in the element substrate 41 has a plurality of scanning lines 411 extending in the X (row) direction and a Y (column) direction. A plurality of data lines 412 are formed extending in the vertical direction. A pixel electrode 413 is provided at each intersection of the plurality of scanning lines 411 and the plurality of data lines 412. Each pixel electrode 413 is a substantially rectangular electrode facing the counter electrode 421 across the liquid crystal 46. Under this configuration, the pixel electrode 413, the counter electrode 421, and the liquid crystal 46 sandwiched between the two electrodes provide a capacitance (hereinafter “liquid crystal capacitance”) for each pixel.
Is formed). Each pixel electrode 413 is a thin film transistor (hereinafter referred to as “TFT (Thin F
ilm Transistor) ”) 414 and electrically connected to the scanning line 411 and the data line 412. Specifically, the gate of the TFT 414 is connected to the scanning line 411, the source is connected to the data line 412, and the drain is connected to the pixel electrode 413. On the other hand, each data line 412 is connected to the data line driving circuit 63 via the sampling circuit 64, and each scanning line 411 is connected to the scanning line driving circuit 61. Elements constituting these driving circuits are formed by a manufacturing process common to the TFT 414 provided for each pixel. Hereinafter, the total number of scanning lines 411 is “m (m is a natural number of 2 or more)”, and the total number of data lines 412 is “6n (n is a natural number of 1 or more)”. The plurality of pixel electrodes 413 are arranged in a matrix of m rows × 6n columns across the X direction and the Y direction. The element substrate 4
On 1, a storage capacitor 416 for preventing leakage of the liquid crystal capacitor is formed for each pixel. One end of the storage capacitor 416 is connected to the pixel electrode 413, and the other end is connected to the capacitor line 417. A constant voltage is applied to the capacitor line 417 via the connection terminal 68.
In the present embodiment, it is assumed that the voltage LCcom is applied to the capacitor line 417.
A configuration may be adopted in which a higher power supply voltage or a lower power supply voltage is applied.

The scanning line driving circuit 61 is a circuit that sequentially selects each of the plurality of scanning lines 411. In FIG. 4, only one scanning line driving circuit 61 is shown in order to prevent the drawing from becoming complicated. The scanning line driving circuit 61 in this embodiment outputs a scanning signal Gj (j is a natural number from 1 to m) that sequentially becomes an active level for each horizontal scanning period to each of the plurality of scanning lines 411 in each vertical scanning period. To do. More specifically, the scanning line driving circuit 61 includes a shift register and a plurality of logical product circuits (all not shown). Of these, the shift register, as shown in FIG. 5, every time the level of the clock signal CLY transits the transfer start pulse DY supplied at the beginning of the vertical scanning period (both rise and fall).
The signals are sequentially shifted and output as signals G1 ′, G2 ′,..., Gm ′. Each AND circuit has a signal G1 '
, G2 ′,..., Gm ′, the logical product of signals adjacent to each other is obtained, and the resulting signals are output as scanning signals G1, G2,. When the scanning signal Gj supplied to the jth scanning line 411 counted from the top in FIG.
The TFTs 414 for one row connected to are simultaneously turned on.

On the other hand, the data line driving circuit 63 is a circuit for applying a voltage to the pixel electrode 413 via each data line 412. The data line driving circuit 63 in this embodiment includes a shift register and a logical product circuit (both not shown), like the scanning line driving circuit 61. Of these, as shown in FIG. 5, the shift register sequentially shifts the transfer start pulse DX supplied at the beginning of the horizontal scanning period every time the level of the clock signal CLX transitions, and signals S1 ′, S2 ′,
..., output as Sn '. Each AND circuit narrows the pulse widths of the signals S1 ′, S2 ′,..., Sn ′ so that adjacent pulses do not overlap with each other, and the signals obtained thereby are used as sampling signals S1, S2,. Output as Sn.

Next, the sampling circuit 64 shown in FIG. 4 samples the image signals VID1 to VID6 supplied via the six image signal lines 66 on each data line 412 according to the sampling signals S1, S2,..., Sn. And each data line 412 has a sampling switch 641. Here, a total of 6n data lines 412 are divided into one block every six lines. Among these blocks, i in FIG. 3 (i is a natural number from 1 to n)
Six sampling switches 641 connected to the data line 412 belonging to the first block
Is supplied with a sampling signal Si from the data line driving circuit 63. Under this configuration, i
The sampling switch 641 connected to the leftmost data line 412 among the six data lines 412 belonging to the second block uses the image signal VID1 supplied via the image signal line 66 as the active level of the sampling signal Si. In this period, the data is sampled and supplied to the data line 412. Similarly, the sampling switch 641 connected to the data line 412 positioned second from the left of the i-th block uses the image signal VID2 supplied via the image signal line 66 as a period during which the sampling signal Si is at an active level. Is sampled and supplied to the data line 412. The same applies to the other data lines 412. That is, the sampling switches 641 connected to the third, fourth, fifth, and sixth data lines 412 from the left of the i-th block respectively receive the image signals VID3, VID4, VID5,
VID6 is sampled and output to the data line 412.

Under the configuration described above, when the scanning signal Gj becomes active level during a certain horizontal scanning period and the 6n TFTs 414 belonging to the j-th row are turned on, the six sampling switches 641 belonging to each block perform sampling. Each block is turned on by the signals S1 to Sn, and the image signal V is applied to the six data lines 412 belonging to the block.
ID1 to VID6 are supplied all at once. As a result, in the horizontal scanning period in which the j-th scanning line 411 is selected, the voltages corresponding to the image signals VID1 to VID6 are applied to the 6n pixel electrodes 413 connected to the scanning line 411 for each block. Will be applied.
Further, if the polarity of each image signal VID is positive in this scanning period, the polarity of the image signal VID is made negative by the amplification / inversion circuit 23 in the next scanning period.
As a result of repeating such an operation in each vertical scanning period, a voltage corresponding to the image signal VID is applied to the pixel electrodes 413 of all the pixels of m rows × 6n columns, and each pixel electrode 413 and the counter electrode 421 are applied. The image is displayed by changing the alignment direction of the liquid crystal 46 in accordance with the potential difference between them.

As described above, the control device 1 shown in FIG. 3 supplies the clock signal CLY and the transfer start pulse DY to the scanning line driving circuit 61, and also supplies the clock signal CLX and the transfer start pulse D.
X is supplied to the data line driving circuit 63, and further, the operation of the processing circuit 2 such as polarity inversion processing of the image signal VID is controlled. Further, a signal for instructing start of display (hereinafter referred to as “operation start signal”) and a signal for instructing stop of display (hereinafter referred to as “operation stop signal”) are input to the control device 1. For example, when an operation element (power button) of an electronic device on which the liquid crystal device 100 is mounted is pressed by the user while an image display operation is being performed, a host device such as a CPU that detects this operation controls the device. An operation stop signal is output to the device 1. On the other hand, when the operator of the electronic device is pressed by the user when the image display operation is not executed,
The host device that detects this outputs an operation start signal to the control device 1.

When the operation start signal or the operation stop signal is input in this way, the control device 1 performs the following in order to remove charges remaining in the liquid crystal capacitor and the storage capacitor 416 (hereinafter collectively referred to as “pixel capacitor”). A series of processes described in (1) are executed. In the following,
Operation executed when an operation stop signal is input (hereinafter referred to as “operation stop sequence”)
And the operation executed when the operation start signal is input (hereinafter referred to as “operation start sequence”). 6 and 7 are diagrams for explaining the contents of the operation stop sequence, and FIGS. 8 and 9 are diagrams for explaining the contents of the operation start sequence.

(1) Operation stop sequence
As shown in FIGS. 6 and 7, when the operation stop signal is input, the control device 1 first
Both the voltages of the image signals VID1 to VID6 and the voltage applied to the counter electrode 421 are changed to the lower power supply voltage (ground potential) GND (step Sa1). More specifically, the control device 1 changes the voltage applied to the counter electrode 421 from the voltage LCcom to the lower power supply voltage GND, and outputs a signal instructing a decrease in the voltages of the image signals VID1 to VID6 to the processing circuit 2. To do. When this signal is input, the amplifying / inverting circuit 23 of the processing circuit 2 does not depend on the contents of the image signals VID1 to VID6 supplied from the S / P conversion circuit 22 thereafter.
The voltage of all the image signal lines 66 is lowered to the lower power supply voltage GND.

Immediately after the processing of step Sa1 is executed, the scanning line driving circuit 61 and the data line driving circuit 63 repeat the same operation as in normal image display. That is, as shown in FIG. 7, the scanning line driving circuit 61 turns on the TFTs 414 in each row by sequentially setting the scanning signals G1, G2,..., Gm to the active level every horizontal scanning period. Further, the data line driving circuit 63 sets the sampling switch 641 to the on state by setting the sampling signals S1, S2,..., Sn to the active level in the horizontal scanning period in which the TFTs 414 of each row are on. However, since the voltages of all the image signal lines 66 are set to the lower power supply voltage GND in step Sa1, one row of the pixel electrodes 413 and one end of the storage capacitor 416 connected to the selected scanning line 411. In other words, the lower power supply voltage GND is applied via the data line 412 and the TFT 414. On the other hand, since the voltage applied to the counter electrode 421 is similarly set to the lower power supply voltage GND in step Sa1, the charge accumulated in the pixel capacitor (liquid crystal capacitor and storage capacitor 416) in the previous display is Completely removed.

On the other hand, when the process of step Sa1 is executed, the control device 1 performs a time corresponding to at least one vertical scanning period after the voltages of the image signals VID1 to VID6 and the applied voltage to the counter electrode 421 are the same in step Sa1. Waits until at least one scan is performed on all pixels after step Sa1 (step Sa).
2). In the present embodiment, the control device 1 performs scanning from the first scanning line 411 to the m-th scanning line 411 in the vertical scanning period next to the vertical scanning period in which the operation stop signal is input. Wait until. When the time corresponding to at least one vertical scanning period has elapsed and the lower power supply voltage GND is applied to one end of the pixel electrode 413 and the storage capacitor 416 of all the pixels, the control device 1 61 and the operation of the data line driving circuit 63 are stopped (step Sa3). More specifically, the control device 1 outputs the transfer start pulse DY to the scanning line drive circuit 61 and the transfer start pulse DX to the data line drive circuit 63.
Stop the output of. As a result, as shown in FIG. 7, all the scanning signals G1, G2,.
m and all sampling signals S1, S2,..., Sn are maintained at an inactive level, and the selection operation by the scanning line driving circuit 61 and the sampling operation by the sampling circuit 64 are stopped.

Thereafter, the control device 1 stops the power supply to the scanning line driving circuit 61 and the data line driving circuit 63 (step Sa4). In step Sa <b> 4, the control device 1 outputs a signal instructing the power supply circuit 3 to stop power supply to the scanning line driving circuit 61 and the data line driving circuit 63. The power supply circuit 3 stops power supply to each drive circuit when this signal is supplied. As described above, in this embodiment, when the operation stop signal is input, the operations of the scanning line driving circuit 61 and the data line driving circuit 63 are stopped, and each drive is performed at a stage where no voltage is applied to the pixel. Since the power supply to the circuit is stopped, no voltage other than the lower power supply voltage GND is applied to each pixel electrode 413 due to the fluctuation of the voltage accompanying the stop of the power supply.
Therefore, the charge accumulated in each electrode is surely removed, and various problems due to the residual charge are prevented.

(2) Operation Start Sequence On the other hand, as shown in FIG. 8, when an operation start signal is input, the control device 1 causes the power supply circuit 3 to start power feeding to the scanning line driving circuit 61 and the data line driving circuit 63. In addition, the scanning line driving circuit 61 and the data line driving circuit 63 are operated (step Sb1). That is, the control device 1 starts to supply the clock signal CLY and the transfer start pulse DY to the scanning line driving circuit 61 and starts to supply the clock signal CLX and the transfer start pulse DX to the data line driving circuit 63. As a result, the scanning line driving circuit 61 scans the scanning signal G every horizontal scanning period.
1, G2,..., Gm are sequentially set to the active level to turn on the TFTs 414 in each row. The data line driving circuit 63 turns on the sampling switch 641 by sequentially setting the sampling signals S1, S2,..., Sn to the active level in the horizontal scanning period in which the TFTs 414 of each row are in the on state. Since all the image signal lines 66 are at the lower power supply voltage GND after the operation stop sequence described above is executed, the selected scanning line 4
11 to the pixel electrode 413 of one row of pixels corresponding to 11 and one end of the storage capacitor 416 to the data line 4
12 and the TFT 414 are applied with the lower power supply voltage GND. on the other hand,
Similarly to the image signal line 66, the voltage of the counter electrode 421 is also maintained at the lower power supply voltage GND. Therefore, even if the charge stored in the pixel capacitor at the time of the previous display operation remains at the start of the operation, the residual charge is accompanied by the operation of the scanning line driving circuit 61 and the data line driving circuit 63 in step Sb1. Completely removed.

Next, the control device 1 starts the operations of the scanning line driving circuit 61 and the data line driving circuit 63 in step Sb1 until a time corresponding to at least one vertical scanning period elapses, that is, after step Sb1. Wait until at least one operation is performed on the pixel (step Sb2). In the present embodiment, after the operation start signal is input, the first scanning line 411 is selected until the m-th scanning line 411 is selected (
That is, it waits for only one vertical scanning period). When the time corresponding to at least one vertical scanning period elapses and the lower power supply voltage GND is applied to all the pixel electrodes 413 and one end of all the storage capacitors 416, the control device 1 Drive circuit 61 and data line drive circuit 63
Is stopped (step Sb3). More specifically, the control device 1 stops the output of the transfer start pulse DY to the scanning line drive circuit 61 and the output of the transfer start pulse DX to the data line drive circuit 63. As a result, as shown in FIG. 9, all the scanning signals G1, G2,..., Gm and all the sampling signals S1, S2,. The selection operation by the drive circuit 61 and the sampling operation by the sampling circuit 64 are stopped.

Thereafter, the control device 1 starts to change the voltage of the counter electrode 421 toward a predetermined value, and at the same time, outputs a signal for changing the voltage of the image signal line 66 to a voltage corresponding to the image signals VID1 to VID6. (Step Sb4). When this signal is input, the amplification / inversion circuit 23 of the processing circuit 2 applies the voltage of each image signal line 66 thereafter to the S / P conversion circuit 22.
Are set to the voltages of the image signals VID1 to VID6 supplied from the. On the other hand, as shown in FIG. 9, the voltage of the counter electrode 421 gradually approaches the intended voltage LCcom. Subsequently, the control device 1 stands by until the voltage of the counter electrode 421 reaches the predetermined voltage LCcom (step Sb5). When the voltage of the counter electrode 421 reaches the predetermined voltage LCcom, the control device 1 restarts the operations of the scanning line driving circuit 61 and the data line driving circuit 63 (step S).
b6). That is, the control device 1 starts supplying the transfer start pulse DY to the scanning line driving circuit 61 and supplying the transfer start pulse DX to the data line driving circuit 63. Thereby, the normal display operation described above is started. As described above, in this embodiment, when the operation start signal is input, the scanning line driving circuit 61 and the data line driving circuit 63 are removed after the charge accumulated in the liquid crystal capacitance and the storage capacitance 416 of each pixel is removed. Since the voltage of the counter electrode 421 and each of the image signal lines 66 is raised to a predetermined value at the stage when the operation is stopped and no voltage is applied to the pixel, each change is accompanied by the change in the voltage. A voltage is not applied to the pixel electrode 413. Therefore, the charge accumulated in each electrode is surely removed, and various problems due to the residual charge are prevented.

<B: Modification>
The embodiment described above is merely an example. Various modifications can be made to this embodiment without departing from the spirit of the present invention. Specifically, the following modifications can be considered.

(1) In the above embodiment, the configuration in which the operation stop signal and the operation start signal are input in accordance with the operation by the user is exemplified. However, the element that triggers the input of these signals is the operation by the user. Not limited. For example, a host device such as a CPU may be configured to output an operation stop signal or an operation start signal when various software is executed, or based on detection signals from various sensors provided in the electronic device. The apparatus may be configured to output an operation stop signal or an operation start signal. For example, a configuration may be employed in which an operation stop signal is output from the host device when a predetermined time has elapsed without any operation being given since the user operated the operating element immediately before. In addition, a so-called foldable electronic apparatus (a display unit in which the electro-optical device is stored and an operation unit in which various operators are disposed is connected via a hinge (
In a typical cellular phone), the host device outputs an operation stop signal when it detects that both units are folded, while the host device outputs an operation start signal when it detects that both units are opened. The structure to do can also be employ | adopted.

(2) In the above embodiment, the configuration in which the operation of the scanning line driving circuit 61 and the data line driving circuit 63 is stopped by stopping the output of the transfer start pulse DY and the transfer start pulse DX is exemplified. The method for stopping the operation is not limited to this. For example, a configuration in which the supply of the clock signal CLX and the clock signal CLY is stopped may be employed instead of or in addition to the configuration in which the supply of the transfer start pulse DY and the transfer start pulse is stopped.

(3) In the above-described embodiment, the configuration in which the voltage of each data line 412 and the counter electrode 421 is changed to the lower power supply voltage GND in the operation stop sequence is illustrated, but the configuration may be changed to a voltage other than this. In short, it is sufficient if each data line 412 and the counter electrode 421 are changed to substantially the same voltage so that the charges stored in the pixel electrodes 413 and the counter electrode 421 are removed.

(4) In the above-described embodiment, the configuration in which both the operation stop sequence and the operation start sequence are executed is exemplified. However, a configuration in which only one of them is executed may be employed. However,
According to the configuration in which both are executed, there is an advantage that the charge accumulated in the pixel capacitor can be more reliably removed than in the configuration in which only one of them is executed.

(5) In the above embodiment, the control device 1, the processing circuit 2, the power supply circuit 3, the scanning line driving circuit 61, the data line driving circuit 63, and the sampling circuit 64 are configured as separate integrated circuits. A part or the whole may be configured as a single integrated circuit. Moreover, the function of the control apparatus 1 may be implement | achieved only by exclusive hardware, and may be implement | achieved when arithmetic control apparatuses, such as CPU, run a program.

<C: Electronic equipment>
Next, an electronic apparatus having the electro-optical device according to the invention will be described.

(1) Projector
FIG. 10 is a plan view showing a configuration of a projector using the electro-optical device according to the present invention (here, the liquid crystal device according to the above embodiment) as a light valve. As shown in the figure,
The projector 2100 includes a lamp unit 210 composed of a white light source such as a halogen lamp.
2 The projection light emitted from the lamp unit 2102 is three mirrors 2104.
And two dichroic mirrors 2108 are separated into light of wavelengths corresponding to the three primary colors of red (R), green (G) and blue (B), and light valves 100R corresponding to the respective colors.
100G and 100B, respectively. Since light corresponding to blue has a longer optical path than light corresponding to other colors, light is guided to the light valve 100B via the relay lens system 2121 in order to prevent loss thereof. The relay lens system 2121 includes an entrance lens 2122, a relay lens 2123, and an exit lens 2124.

Here, the light valves 100R, 100G, and 100B have the same configuration as the liquid crystal panel 4 according to the above-described embodiment, and are driven by image signals corresponding to the respective colors of red, green, and blue supplied from the processing circuit 2. Is done. The light modulated by these light valves 100R, 100G, and 100B enters the dichroic prism 2112 from different directions. In the dichroic prism 2112, red and blue light is refracted by 90 degrees, while green light goes straight. Under this configuration, a color image obtained by combining the images of the respective colors is projected onto the screen 2120 by the projection lens 2114.

(2) Personal computer
First, an example in which the electro-optical device according to the present invention is applied to a display unit of a portable personal computer (so-called notebook personal computer) will be described. FIG. 11 is a perspective view showing the configuration of the personal computer. As shown in FIG.
Reference numeral 0 denotes a main body 2204 having a keyboard 2202 and the liquid crystal device 10 according to the embodiment.
And a display portion 2206 having zero.

In addition to the projector shown in FIG. 10 and the personal computer shown in FIG. 11, examples of electronic equipment that can use the electro-optical device according to the present invention include a liquid crystal television and a viewfinder type (or a monitor direct view type). Video recorder, car navigation device, pager, electronic notebook, calculator, word processor, workstation, videophone, POS
Examples include terminals and devices equipped with touch panels.

It is a block diagram which shows the structure of the liquid crystal device which concerns on embodiment of this invention. It is a perspective view which shows the structure of a liquid crystal panel among the liquid crystal devices. It is sectional drawing seen from the III-III line in FIG. It is a block diagram which shows the electrical structure of the element provided in the element board | substrate among the liquid crystal panels. 3 is a timing chart for explaining operations of a scanning line driving circuit and a data line driving circuit. It is a flowchart which shows the content of the operation stop sequence. It is a timing chart which shows the waveform of each signal when an operation stop sequence is performed. It is a flowchart which shows the content of an operation | movement start sequence. It is a timing chart which shows the waveform of each signal when an operation start sequence is performed. It is a top view which shows the structure of the projector which is an example of the electronic device concerning this invention. It is a perspective view which shows the structure of the personal computer which is an example of the electronic device which concerns on this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 100 ... Liquid crystal device (electro-optical device), 1 ... Control device, 2 ... Processing circuit, 3 ... Power supply circuit, 4 ... Liquid crystal panel, 41 ... Element substrate, 411 ... Scanning line, 412 ... Data line,
413: Pixel electrode, 414: TFT (switching element), 416: Storage capacitor, 4
17... Capacitance line 42. Counter substrate 421. Counter electrode 61 61 Scan line drive circuit 6
3. Data line driving circuit, 64 ... Sampling circuit, 66 ... Image signal line, 45 ... Sealing material, 46 ... Liquid crystal (electro-optical material).

Claims (4)

A pixel electrode electrically connected to each scanning line and each data line via a switching element provided corresponding to each intersection of the plurality of scanning lines and the plurality of data lines, and an electro-optic material interposed therebetween A counter electrode facing the pixel electrode; a scanning line driving circuit that sequentially selects each of the plurality of scanning lines to turn on a switching element corresponding to the scanning line; and an on state by the scanning line driving circuit In a method of controlling an electro-optical device comprising: a data line driving circuit that supplies an image signal to each of the pixel electrodes connected to the switching element, which is connected to each of the data lines.
When a display start signal instructing the start of display is input, selection by the scanning line driving circuit in a state where the voltage of the image signal supplied to the pixel electrode and the voltage applied to the counter electrode are substantially the same voltage Is executed for all the scanning lines, the operation of the scanning line driving circuit and the data line driving circuit is stopped,
After the operation of the scanning line driving circuit and the data line driving circuit is stopped, the applied voltage to the counter electrode is changed toward a predetermined value,
An electro-optical device control method for starting operations of the scanning line driving circuit and the data line driving circuit after an applied voltage to the counter electrode reaches the predetermined value. A pixel electrode electrically connected to each scanning line and each data line via a switching element provided corresponding to each intersection of the plurality of scanning lines and the plurality of data lines;
A counter electrode facing the plurality of pixel electrodes with an electro-optic material interposed therebetween;
A scanning line driving circuit for sequentially selecting each of the plurality of scanning lines and turning on a switching element corresponding to the scanning line;
A data line driving circuit for supplying an image signal to each of the pixel electrodes connected to the switching element turned on by the scanning line driving circuit via the data lines;
When a display start signal instructing the start of display is input, selection by the scanning line driving circuit in a state where the voltage of the image signal supplied to the pixel electrode and the voltage applied to the counter electrode are substantially the same voltage Is executed for all the scanning lines, and stopping means for stopping the operations of the scanning line driving circuit and the data line driving circuit;
Voltage control means for changing the voltage applied to the counter electrode toward a predetermined value after the operations of the scanning line driving circuit and the data line driving circuit are stopped;
A control device for an electro-optical device, comprising: start means for starting operations of the scanning line driving circuit and the data line driving circuit after a voltage applied to the counter electrode reaches the predetermined value.   An electro-optical device comprising the control device according to claim 2.   An electronic apparatus comprising the electro-optical device according to claim 3.

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