JP6372137B2 - Electro-optical device, control method of electro-optical device, and electronic apparatus - Google Patents

Description

The present invention relates to an electro-optical device, a control method for the electro-optical device, a driving circuit for an electro-optical panel, and an electronic apparatus.

An electro-optical device that displays an image using a liquid crystal element has been widely developed. In this electro-optical device, an image signal designating the display gradation of each pixel is supplied to each pixel via a data line, so that the transmittance of the liquid crystal included in each pixel corresponds to the designated gradation of the image signal. To control the transmittance
Thereby, the gradation designated by the image signal is displayed on each pixel.

By the way, when the supply of the image signal is insufficient, such as when the time for supplying the image signal to each pixel cannot be sufficiently secured, it becomes impossible for each pixel to accurately display the gradation specified by the image signal. The display quality may be reduced. In order to cope with such a problem of deterioration in display quality due to insufficient writing of the image signal to the pixel, a precharge signal having a potential close to the potential of the image signal is applied to each pixel or data line. By supplying before supplying,
A technique that facilitates writing of an image signal to each pixel has been proposed (for example, Patent Document 1).
).

JP 2010-102217 A

When supplying a precharge signal prior to supplying an image signal, it is common to supply a precharge signal having a predetermined signal level regardless of the level of the signal level of the image signal.
For this reason, when the precharge signal is supplied, the fluctuation amount of the potential of the data line is increased as compared with the case where the precharge signal is not supplied. When the fluctuation amount of the potential of the data line increases,
When the potential fluctuation propagates to the pixel through a parasitic capacitance between the data line and the pixel,
There is a problem in that the pixel cannot accurately display the gradation specified by the image signal. Further, when the fluctuation amount of the potential of the data line increases, there is a problem that the power consumption of the electro-optical device increases.

Furthermore, when performing polarity inversion driving that periodically inverts the polarity of an image signal for the purpose of preventing a DC component from being applied to the liquid crystal, the signal level of the precharge signal is set to the signal level of the image signal. It may be at the above level. In this case, the above-described problems of an increase in the amount of fluctuation of the potential of the data line and an increase in the amount of power consumption of the electro-optical device become apparent.
In this case, a high drive capability is required for the drive circuit that supplies the precharge potential.
The manufacturing cost of the electro-optical device may be increased.

The present invention has been made to address at least one of the above-described problems, and one of its purposes is to provide a technique for performing precharge while suppressing fluctuations in the potential of the data line. is there.

In order to solve the above problems, an electro-optical device according to the invention includes a liquid crystal element including a first electrode, a second electrode, and a liquid crystal provided between the first electrode and the second electrode. A pixel, an electrode signal supply unit that supplies an electrode signal to the first electrode, and a data signal supply unit that supplies a data signal to the second electrode. The data signal supply unit includes a first period. And a second period following the first period, the potential of the data signal is set to a precharge potential,
In a third period subsequent to the second period, the potential of the data signal is set to a data potential for designating a gradation to be displayed by the pixel, and the electrode signal supply unit includes the electrode signal in the first period. Is set to a first potential, and the potential of the electrode signal is set to a second potential having a polarity opposite to that of the first potential with respect to the precharge potential in the second period and the third period. It is characterized by setting.

According to the present invention, the potential of the electrode signal with reference to the precharge potential is the first period and the second period.
The liquid crystal element changes with respect to the amount of change in the potential of the data signal as compared with the case where the potential of the electrode signal does not change between the first period and the second period because the polarity changes to the opposite period. The amount of change in the voltage applied to can be increased. As a result, the amount of change in the voltage applied to the liquid crystal element can be efficiently increased without increasing the amount of change in the potential of the data signal, so that the drive capability of the data signal supply unit can be kept low. In addition, the power consumption of the electro-optical device can be reduced.

In the above-described electro-optical device, the data signal supply unit may be configured to output the data potential.
It is preferable that the second potential is set so as to have the same polarity as the precharge potential.

According to this aspect, since the precharge potential in the second period and the data potential in the third period have the same polarity with respect to the second potential, the second period is compared with the case where the polarity is not the same. Writing data signals to the two electrodes is facilitated.

The electro-optical device according to the invention includes a data line, a plurality of scanning lines intersecting with the data line, a plurality of pixels provided corresponding to the intersection of the data line and the plurality of scanning lines, A scanning line driving unit that selects the scanning line; a data signal supply unit that supplies a data signal to the data line; and an electrode signal supply unit that supplies an electrode signal to a first electrode. A first electrode; a second electrode; and a liquid crystal element including a liquid crystal provided between the first electrode and the second electrode. The data signal supply unit includes a first period of the first unit period. And a second period following the first period, the potential of the data signal is set to a first precharge potential, and among the first unit period, a third period following the second period, The potential of the data signal is set to the first unit period. Is set to a first data potential for designating a gradation to be displayed by a pixel provided corresponding to a scanning line selected by the scanning line driving unit, and a second unit period subsequent to the first unit period is set to a first data potential. In a fourth period and a fifth period subsequent to the fourth period, the potential of the data signal is set to a second precharge potential, and the fifth unit period includes the fifth precharge potential.
In a sixth period subsequent to the period, the second data that designates the potential of the data signal and the gradation displayed by the pixel provided corresponding to the scanning line selected by the scanning line driver in the second unit period The electrode signal supply unit sets the potential of the electrode signal to a first potential lower than the first precharge potential and the second precharge potential in the first period and the fifth period. 1 potential is set, and the potential of the electrode signal is set to a second potential higher than the first precharge potential and the second precharge potential in the second period and the fourth period. It is characterized by.

According to the present invention, the polarity of the electrode signal is reversed with the precharge potential as a reference during the period in which the precharge is performed. For this reason, compared to the case where the polarity of the electrode signal does not change during the precharge period, the amount of change in the voltage applied to the liquid crystal element relative to the amount of change in the potential of the data signal can be increased. it can. Thereby, the voltage applied to the liquid crystal element can be greatly changed without greatly changing the potential of the data signal,
The drive capability of the data signal supply unit can be kept low, and the power consumption of the electro-optical device can be reduced.

In the electro-optical device described above, the electrode signal supply unit sets the potential of the electrode signal to the second potential in the third period, and sets the potential of the electrode signal in the sixth period. It is preferable that the first potential is set to be the first potential, the first data potential is lower than the second potential, and the second data potential is higher than the first potential.

According to this aspect, the precharge potential at the end of the precharge and the data potential set after the precharge have the same polarity with respect to the potential of the electrode signal applied to the first electrode, and thus are not the same polarity. Compared to the case, the data signal can be easily written.

In addition, an electronic apparatus according to the present invention includes any one of the above electro-optical devices. Examples of such electronic devices include a car navigation device, a personal computer, a television, a projection display device, and a mobile phone.

The electro-optical device control method according to the present invention includes a pixel including a liquid crystal element including a first electrode, a second electrode, and a liquid crystal provided between the first electrode and the second electrode. A method of controlling an electro-optical device comprising: setting a potential of an electrode signal supplied to the first electrode to a first potential and precharging a potential of a data signal supplied to the second electrode in the first period. The potential of the electrode signal is set to a second potential having a polarity opposite to the first potential with reference to the precharge potential in a second period following the first period; The potential of the data signal is set to the precharge potential, the potential of the electrode signal is set to the second potential in a third period subsequent to the second period, and the potential of the data signal is set to display the pixel. Specifies the gradation to be used. Set to data potential, characterized in that.

According to the present invention, the potential of the electrode signal with reference to the precharge potential is the first period and the second period.
Since the polarity changes with the period, the change amount of the voltage applied to the liquid crystal element with respect to the change amount of the potential of the data signal can be increased. As a result, the power consumption of the electro-optical device can be reduced.

The electro-optical panel drive circuit according to the present invention includes a first electrode, a second electrode, and the first electrode.
An electro-optical panel driving circuit including a pixel including a liquid crystal element including an electrode and a liquid crystal provided between the second electrode, and an electrode signal supply unit that supplies an electrode signal to the first electrode; A data signal supply unit for supplying a data signal to the second electrode, wherein the data signal supply unit pre-charges the potential of the data signal in a first period and a second period subsequent to the first period. The charge potential is set, and in a third period subsequent to the second period, the potential of the data signal is set to a data potential for designating a gradation to be displayed by the pixel, and the electrode signal supply unit In the period, the potential of the electrode signal is set to a first potential, and in the second period and the third period, the potential of the electrode signal is a potential having a polarity opposite to that of the first potential with respect to the precharge potential. In Set to the second potential, characterized in that.

According to the present invention, the potential of the electrode signal with reference to the precharge potential is the first period and the second period.
Since the polarity changes with the period, the change amount of the voltage applied to the liquid crystal element with respect to the change amount of the potential of the data signal can be increased. Thereby, the power consumption of the electro-optical panel can be reduced.

1 is a block diagram of an electro-optical device according to a first embodiment of the invention. FIG. It is a circuit diagram of a pixel circuit. 6 is a timing chart for explaining the operation of the electro-optical device. It is explanatory drawing for demonstrating the image which input image data shows. It is a timing chart for demonstrating the data signal and common electrode signal which are supplied to a pixel circuit. 6 is a timing chart for explaining the operation of the electro-optical device according to Comparative Example 1. 6 is a timing chart for explaining the operation of the electro-optical device according to Comparative Example 2; It is explanatory drawing for demonstrating leak current. It is explanatory drawing for demonstrating leak current. It is explanatory drawing for demonstrating the magnitude | size of the leakage current which concerns on the contrast 2. FIG. It is explanatory drawing for demonstrating the magnitude | size of the leakage current which concerns on the contrast 2. FIG. It is explanatory drawing for demonstrating vertical crosstalk. It is explanatory drawing for demonstrating the magnitude | size of a leakage current. It is explanatory drawing for demonstrating the magnitude | size of a leakage current. 12 is a timing chart for explaining the operation of the electro-optical device according to the second embodiment. It is explanatory drawing for demonstrating the magnitude | size of a leakage current. It is a perspective view of an electronic device (projection type display device). It is a perspective view of an electronic device (personal computer). It is a perspective view of an electronic device (cellular phone).

Hereinafter, embodiments for carrying out the present invention will be described with reference to the drawings. However, in each figure, the size and scale of each part are appropriately changed from the actual ones. Further, since the embodiments described below are preferable specific examples of the present invention, various technically preferable limitations are attached thereto. However, the scope of the present invention is particularly limited in the following description. Unless otherwise stated, the present invention is not limited to these forms.

<A. First Embodiment>
FIG. 1 is a block diagram of an electro-optical device 1 according to the first embodiment of the present invention.
The electro-optical device 1 includes an electro-optical panel 10 and a display control circuit 50.
The electro-optical panel 10 includes a display unit 30 in which a plurality of pixel circuits PX are arranged, and each pixel circuit PX.
And a drive circuit 20 for driving
The display unit 30 includes M scanning lines 32 in the first to Mth rows extending in the x direction and N columns in the first to Nth columns extending in the y direction intersecting the x direction. Data lines 34 are formed (M and N
Is a natural number). The plurality of pixel circuits PX are arranged in a matrix of vertical M rows × horizontal N columns corresponding to each intersection of the scanning lines 32 and the data lines 34 in the display unit 30. In this embodiment,
The pixel circuit PX is arranged at all of the M × N intersections of the M scanning lines 32 and the N data lines 34, and is arranged at a part of the M × N intersections. It does not matter.

The drive circuit 20 includes a scan line drive circuit 22 (an example of a “scan line drive unit”), a data line drive circuit 24 (an example of a “data signal supply unit”), and a power supply circuit 26 (an “electrode signal supply unit”). For example).
The scanning line driving circuit 22 supplies the scanning signal G [m] (m is a natural number satisfying 1 ≦ m ≦ M) to each scanning line 32, so that the scanning lines 32 of the first to Mth rows are set to one. One for each horizontal scanning period H is selected in turn. More specifically, the scanning line driving circuit 22 selects the scanning line 32 in the m-th row by setting the scanning signal G [m] to a predetermined selection potential.
The data line driving circuit 24 synchronizes with the selection of the scanning line 32 by the scanning line driving circuit 22, and N
A data signal Vd [n] (n is a natural number satisfying 1 ≦ n ≦ N) is supplied to each of the data lines 34. The data signal Vd [n] is variably set according to the display gradation specified by the input image data Din, which will be described later, for the pixel corresponding to each pixel circuit PX.
The power supply circuit 26 supplies a common electrode signal Vcom (an example of an “electrode signal”) to each pixel circuit PX.

FIG. 2 is a circuit diagram of each pixel circuit PX.
As shown in FIG. 2, each pixel circuit PX includes a liquid crystal element CL and a writing transistor Tr (an example of a “selection switch”).
The liquid crystal element CL includes a common electrode 41 (an example of “first electrode”), a pixel electrode 42 (an example of “second electrode”), and a liquid crystal 43 provided between the common electrode 41 and the pixel electrode 42. Including. The liquid crystal 43 of the liquid crystal element CL has a voltage applied to the liquid crystal element CL, more precisely, the common electrode 41.
The transmittance is changed according to the voltage applied between the pixel electrode 42 and the pixel electrode 42. A configuration in which an auxiliary capacitor is connected in parallel to the liquid crystal element CL can also be adopted.
In the present embodiment, the write transistor Tr has N gates connected to the scanning lines 32.
A channel type transistor is provided between the liquid crystal element CL and the data line 34 and controls the electrical connection (conduction / non-conduction) between the two. When the scanning signal G [m] is set to the selection potential, the writing transistor Tr in each pixel circuit PX in the m-th row is simultaneously turned on.
Hereinafter, for convenience of description, a connection wiring that electrically connects the write transistor Tr and the pixel electrode 42 is referred to as a node Q, and a connection wiring that electrically connects the data line 34 and the write transistor Tr. This is called node R. Hereinafter, the potential of the node Q is referred to as a potential Vq.

At the timing when the scanning line 32 corresponding to the pixel circuit PX is selected and the writing transistor Tr of the pixel circuit PX is controlled to be turned on, the data signal Vd [n] from the data line 34 is transmitted to the pixel circuit PX. Supplied. The node Q (and the pixel electrode 42) of the pixel circuit PX is set to the potential indicated by the data signal Vd [n]. Thereby, a voltage (potential difference VCL) corresponding to the data signal Vd [n] is applied to the liquid crystal element CL, and the liquid crystal 43 of the pixel circuit PX is set to a transmittance corresponding to the data signal Vd [n]. Therefore, the pixel corresponding to the pixel circuit PX displays a gradation corresponding to the data signal Vd [n].
Hereinafter, the voltage applied to the liquid crystal element CL may be expressed as a potential difference VCL obtained by subtracting the potential of the common electrode signal Vcom from the potential Vq.

After the voltage corresponding to the data signal Vd [n] is applied to the liquid crystal element CL of the pixel circuit PX, when the writing transistor Tr is turned off, ideally, the liquid crystal element has the liquid crystal capacitance of the liquid crystal element CL. The voltage applied to CL is held. Therefore, each pixel ideally displays the gradation specified by the data signal Vd [n] in the period from when the writing transistor Tr is turned on until the next turning on. .
However, actually, a leakage current Ids may occur in the off-state write transistor Tr. In this case, the potential Vq varies.
In addition, a capacitance may be parasitic between the data line 34 and the node Q or between the data line 34 and the pixel electrode 42. In this case, the potential variation of the data line 34 may propagate to the node Q, the pixel electrode 42, etc. via the parasitic capacitance, and the potential Vq may vary.
When such a variation in the potential Vq occurs, the potential difference VCL also varies, so that the pixel cannot accurately display the gradation corresponding to the data signal Vd [n].

Returning to FIG.
As shown in FIG. 1, input image data Din is supplied to the display control circuit 50 from a host device such as a host computer (not shown) in synchronization with a synchronization signal. Here, the input image data Din is data defining the gradation to be displayed by the pixel corresponding to each pixel circuit PX. For example, the input image data Din may be digital data that defines the gradation to be displayed in each pixel by 8 bits. The synchronization signal is a signal including, for example, a vertical synchronization signal Vsnc and a horizontal synchronization signal Hsnc described later, a dot clock signal, and the like.

The display control circuit 50 is based on the synchronization signal supplied from the host device.
A control signal Ctr which is a signal for controlling the operation of 0 is generated, and the control signal Ctr is generated as the drive circuit 2.
Supply to zero. Here, the control signal Ctr is, for example, a signal including a vertical synchronization signal Vsnc, a horizontal synchronization signal Hsnc, a polarity signal Pol, a clock signal, an enable signal, and the like.
Further, the display control circuit 50 generates an image data signal Dx based on the input image data Din and supplies it to the data line driving circuit 24. In the present embodiment, the image data signal Dx is a digital signal, but may be an analog signal.

FIG. 3 is a timing chart showing the operation of the electro-optical device 1. As shown in this figure, the operation period of the electro-optical device 1 is divided into a plurality of display periods F by the vertical synchronization signal Vsnc. Each display period F is divided into at least M horizontal scanning periods H by the horizontal synchronization signal Hsnc.
It is divided into.

The polarity signal Pol is a signal whose polarity is inverted every display period F and whose polarity is inverted every horizontal scanning period H. More specifically, the display control circuit 50 sets the potential of the polarity signal Pol to a low level in the odd-numbered horizontal scanning period H in one display period F, and in the even-numbered horizontal scanning period H. On the other hand, among other display periods F subsequent to one display period F, the high level is set in the odd-numbered horizontal scanning period H, and the high level is set in the even-numbered horizontal scanning period H. Set to level.
Hereinafter, the horizontal scanning period H in which the polarity signal Pol is set to the low level is referred to as the negative polarity period U1 (
The horizontal scanning period H in which the polarity signal Pol is set to a high level is referred to as a positive polarity period U2 (an example of a “second unit period”).

The scanning line driving circuit 22 sets the scanning signals G [1] to G [M] to a predetermined selection potential in order for each horizontal scanning period H. Specifically, the scanning line driving circuit 22 includes m in each display period F.
In the first horizontal scanning period H, the scanning signal G [m] is set to a predetermined selection potential, and the other scanning signals G [1] to G [m−1] and G [m + 1] to G [M] are set. A non-selection potential that is lower than a predetermined selection potential is set.

As shown in FIG. 3, the drive circuit 20 divides the negative period U1 into a period T1 (an example of “first period”) and a period T2 (“second period” following the period T1 based on the control signal Ctr. And a period T3 (an example of a “third period”) subsequent to the period T2, and a positive polarity period U2 is followed by a period T4 (an example of a “fourth period”) and the period T4. Period T5 (an example of “fifth period”) to be performed and a period T6 (an example of “sixth period”) subsequent to period T5.

Further, as shown in FIG. 3, the power supply circuit 26 has a potential of the common electrode signal Vcom lower than a predetermined reference potential VcomM in a period T1, a period T5, and a period T6. The potential VcomL (an example of “first potential”) is set, and the potential of the common electrode signal Vcom is higher than the reference potential VcomM in the periods T2, T3, and T4 (“second potential”). Example of “potential”).

As shown in FIG. 3, the data line driving circuit 24 has a precharge potential in which the potential of the data signal Vd [n] is higher than the potential VcomL and lower than the potential VcomH in the periods T1 and T2. Vpr1 (an example of the “first precharge potential”) is set, and in the periods T4 and T5, the potential of the data signal Vd [n] is higher than the potential VcomL and the potential Vc.
Precharge potential Vpr2 (an example of “second precharge potential”) that is lower than omH
Set to.
In the present embodiment, as an example, the precharge potential Vpr1 and the precharge potential Vp
r2 is set to a potential equal to a predetermined reference potential VdM.
However, the precharge potential Vpr1 and the precharge potential Vpr2 may be different from each other or different from the reference potential VdM.

As shown in FIG. 3, in the period T3 included in the mth horizontal scanning period H, the data line driving circuit 24 sets the potential of the data signal Vd [n] and the input image data Din is in the mth row and nth column. The data potential Vdt1 [n] (an example of “first data potential”) that is a potential determined based on the display gradation designated for the pixel and is equal to or lower than the potential VcomH. In addition, the data line driving circuit 24 sets the potential of the data signal Vd [n] and the input image data Din in the (m + 1) th row and nth column in the period T6 included in the (m + 1) th horizontal scanning period H. Is set to a data potential Vdt2 [n] (an example of a “second data potential”) that is a potential determined based on the display gradation specified with respect to V and is equal to or higher than the potential VcomL.
That is, in the data line driving circuit 24, in the negative polarity period U1, the potential Vq of the common electrode 41 is equal to or lower than the potential of the pixel electrode 42 (the potential indicated by the common electrode signal Vcom), and the potential difference VCL is 0.
A negative data potential Vdt1 [n] that is V or less is supplied to the pixel circuit PX, and the positive period U2
, The potential Vq of the common electrode 41 is equal to or higher than the potential of the pixel electrode 42 (potential indicated by the common electrode signal Vcom), and the positive data potential Vdt2 [n] at which the potential difference VCL is 0 V or higher is supplied to the pixel circuit PX. To do.

In the present embodiment, it is assumed that the dynamic ranges of the data potentials Vdt1 [n] and Vdt2 [n] match. Specifically, the highest potential that the data potentials Vdt1 [n] and Vdt2 [n] can take is called the potential VdH, and the lowest potential is called the potential VdL.
In the present embodiment, the precharge potentials Vpr1 and Vpr2 are equal to or higher than the potential VdH.
Further, it is assumed that the potential is equal to or lower than VdL.

In the following, each pixel circuit PX is driven by the drive circuit 20 (that is, the data signal Vd [n] is supplied to each pixel circuit PX by the data line drive circuit 24, and each pixel circuit PX is supplied by the power supply circuit 26. Drive in the negative polarity period U1 is referred to as “negative polarity drive”, and drive in the positive polarity period U2 is referred to as “positive polarity drive”.

Of the various potentials described above, the data potential Vdt1 [n] and the data potential Vdt2 [n] are variably set for each horizontal scanning period H in accordance with the input image data Din. The charge potential Vpr2, the potential VcomL, and the potential VcomH are constants whose values do not change every display period F or each horizontal scanning period H.

Next, the operation of the pixel circuit PX when displaying an image on the display unit 30 will be described with reference to FIG. 4 and FIG.
In the numerical example, it is assumed that the electro-optical device 1 is in a normally white mode in which the pixel displays “white” in a state where no voltage is applied to the liquid crystal element CL.
In the numerical example, when the voltage (potential difference VCL) applied to the liquid crystal element CL is 0 V,
When the pixel including the liquid crystal element CL displays “white” and the voltage (absolute value of the potential difference VCL) applied to the liquid crystal element CL is 8 V, the pixel including the liquid crystal element CL displays “black”. Assume.
In the numerical example, in the electro-optical device 1, the reference potential VcomM and the reference potential VdM are both “0V”, the potential VcomH and the potential VdH are both “+ 4V”, and both the potential VcomL and the potential VdL are “−”. 4V "is assumed (see FIG. 5).

FIG. 4 is an explanatory diagram for explaining the image indicated by the input image data Din, that is, the gradation specified by the input image data Din for each pixel in the numerical example described below. As shown in this figure, in the numerical example, the image indicated by the input image data Din has a “black” window displayed in the center with “gray” being an intermediate color between “white” and “black” as a background. Assume an image. Hereinafter, the image shown in this figure is referred to as an “exemplary image”.
In this numerical example, the voltage (absolute value of the potential difference VCL) applied to the liquid crystal element CL is 3V.
In this case, it is assumed that the pixel including the liquid crystal element CL displays “gray”.
Further, as shown in FIG. 4, pixels representing the “gray” background include pixels a (
However, ma is a natural number satisfying 1 ≦ ma <M) and the pixel b in the mb row and the nth column (note that mb
= Ma + 1) is included, and the pixel representing the “black” window includes the pixel c in the mc-th row and the n-th column (where mc is a natural number satisfying mb <mc <M) and the md-th row. Pixel d in the nth column
(However, md = mc + 1) is included.

5 shows the data signal Vd [n] and the common electrode signal Vcom supplied to each of the pixels a to d and the pixels a to when the electro-optical device 1 displays the exemplary image shown in FIG. It is explanatory drawing for demonstrating the relationship with the voltage (potential difference VCL) applied to each liquid crystal element CL of d.

Of these, FIG. 5A shows the negative polarity period U1 during which the ma-th scanning line 32 is selected.
In the state in which the drive circuit 20 drives the pixel a in the negative polarity and the data signal Vd [n] is supplied to the pixel a and in the positive polarity period U2 in which the scanning line 32 in the mb-th row is selected, the drive circuit 20 Pixel b
Is a positive polarity drive, and a state in which the data signal Vd [n] is supplied to the pixel b is an explanatory diagram.

As shown in FIG. 5A, in the negative polarity period U1 in which the scanning line 32 of the ma-th row is selected,
The potential difference VCL in the pixel a is set to “+ 4V” in the period T1, and “−4V” in the period T2.
Is set to "-3V" in the period T3. As a result, the potential difference VCL in the pixel a is set to “−3 V”, and the pixel a displays “gray” until the scanning line 32 in the ma-th row is selected in the next display period F.
In the positive polarity period U2 in which the mb-th scanning line 32 is selected, the potential difference VCL in the pixel b is set to “−4 V” in the period T4, set to “+4 V” in the period T5, and in the period T6. Set to “+ 3V”. As a result, the potential difference VCL at the pixel b is set to “+3 V”, and during the next display period F, the pixel b is scanned until the mb-th scanning line 32 is selected.
Displays “gray”.

FIG. 5B shows the driving circuit 2 in the negative polarity period U1 in which the mc-th scanning line 32 is selected.
A state in which the pixel c drives the pixel c to have a negative polarity and the data signal Vd [n] is supplied to the pixel c;
FIG. 10 is an explanatory diagram showing a state in which the drive circuit 20 drives the pixel d in the positive polarity period U2 during which the row scanning line 32 is selected, and the data signal Vd [n] is supplied to the pixel d. .

As shown in FIG. 5B, in the negative polarity period U1 in which the mc-th scanning line 32 is selected,
The potential difference VCL in the pixel c is set to “+ 4V” in the period T1, and “−4V” in the period T2.
Is set to “−8V” in the period T3. As a result, the potential difference VCL at the pixel c is set to “−8 V”, and the pixel c displays “black” until the scanning line 32 of the mc-th row is selected in the next display period F.
Further, in the positive polarity period U2 in which the md-th scanning line 32 is selected, the potential difference VCL in the pixel d is set to "-4V" in the period T4, set to "+ 4V" in the period T5, and in the period T6. It is set to “+ 8V”. As a result, the potential difference VCL at the pixel d is set to “+8 V”, and during the next display period F, until the md-th scanning line 32 is selected, the pixel d
Displays “black”.

Next, in order to explain the effect of the present embodiment, a mode in which the potential of the common electrode signal Vcom is fixed to the reference potential VcomM as shown in FIG. 6 (hereinafter, the mode shown in FIG. Will be described.
In the electro-optical device according to the proportional 1 shown in FIG. 6, the common electrode signal Vcom is the reference potential Vc.
For example, in order to display “black” of the image shown in FIG. 4 in the above numerical example, the data potential Vdt1 [n] is set to “omM” (“0V” in the above numerical example). −8V ”and the data potential Vdt2 [n] needs to be“ + 8V ”. That is, in the comparative example 1, in order to change the potential difference VCL in the range of 16V from “−8V” to “+ 8V” in the numerical example described above, the potential of the data signal Vd [n] is changed from “−8V” to “−8V”. + 8V "16
It is necessary to change the width of V.

On the other hand, the electro-optical device 1 according to the present embodiment is, for example, in the numerical example described above,
By changing the potential of the data signal Vd [n] in a range of 8V from “−4V” to “+ 4V”,
The potential difference VCL can be changed in a range of 16V from “−8V” to “+ 8V”. That is, the electro-optical device 1 according to the present embodiment can suppress the change width of the potential of the data signal Vd [n] with respect to the change width of the potential difference VCL, as compared with the comparative 1. For this reason, the electro-optical device 1 according to the present embodiment can suppress the driving capability of the data line driving circuit 24 to be lower than that of the comparative 1 and the potential fluctuation of the data line 34 propagates to the node Q and the like. It is possible to suppress deterioration in display image quality caused by doing so.

In contrast 1, since precharge is executed while the potential of the common electrode signal Vcom is fixed, for example, in the numerical example described above, at the start of the period T1 or the start of the period T4, the maximum is 12V. Potential fluctuation occurs.
On the other hand, in the present embodiment, the polarity of the potential difference VCL in each horizontal scanning period H is inverted by changing the potential of the data signal Vd [n] (precharge potential) instead of changing the potential of the common electrode signal Vcom. Since it is realized by changing, for example, in the numerical example described above,
The fluctuation range of the potential at the start of the period T1 or the start of the period T4 can be suppressed to 4 V at the maximum.
In other words, in the present embodiment, compared with the comparative 1, the change width of the potential of the data signal Vd [n] generated for executing the precharge can be suppressed to be small. Then, by suppressing the change width of the change width of the precharge potential to be small, it is possible to suppress display image quality deterioration due to propagation of the potential fluctuation of the data line 34 to the node Q or the like. Further, since the change width of the change width of the precharge potential can be suppressed to be small, sufficient precharge can be executed even when the driving capability of the data line driving circuit 24 is low, and the data potential of the pixel is reduced. Sufficient writing becomes possible.

In the present embodiment, in each horizontal scanning period H (negative polarity period U1, positive polarity period U2), a positive voltage (voltage at which the potential difference VCL becomes positive) and a negative polarity are applied to each liquid crystal element CL. (The voltage at which the potential difference VCL is negative) is applied. For this reason, in this embodiment, compared with the comparative 1, the direct current component applied to the liquid crystal 43 of the liquid crystal element CL can be reduced, and the probability of occurrence of image sticking can be kept low.

In this embodiment, since the polarity of the polarity signal Pol is inverted every display period F, the direct current component applied to the liquid crystal 43 of the liquid crystal element CL can be reduced, and the probability of image sticking can be kept low.

Note that the potential fluctuation range of the data line 34 is narrowed, and the data potential (Vdt1 [
n], Vdt2 [n]) is facilitated by setting the common electrode signal Vcom to the potential VcomH in the whole negative period U1 (periods T1 to T3) as shown in FIG. All of U2 (
It is also possible to realize a mode in which the common electrode signal Vcom is set to the potential VcomL in the period T4 to T6) (hereinafter, the mode shown in FIG. 7 is referred to as “comparative 2”).
However, in the case of the comparative 2, the influence of the leakage current Ids generated in the off state of the writing transistor Tr is larger than that of the present embodiment, and the image quality deterioration due to the leakage current Ids, for example, vertical crosstalk The probability of occurrence increases.

Hereinafter, as a premise for explaining the effect of the present embodiment of suppressing the vertical crosstalk, the proportional 2
As an example, the occurrence of vertical crosstalk due to the leakage current Ids will be described.
Note that the electro-optical device according to the comparative example 2 applies the common electrode signal Vcom to the potential Vco in the period T1.
It is assumed that the configuration is the same as that of the electro-optical device 1 according to the present embodiment except that it is set to mH and the common electrode signal Vcom is set to the potential VcomL in the period T4.

FIG. 8 is an explanatory diagram for explaining the relationship between the operating characteristics of the N-channel transistor and the leakage current Ids.
For example, in an N-channel transistor, as shown in FIG. 8A, the gate potential with respect to the source becomes high, and the potential difference Vgs between the source and the gate becomes equal to or higher than the threshold voltage Vth of the transistor, thereby turning on the operation region. In this case, the transistor is turned on, and a current flows from the drain to the source. On the contrary, in the off operation region where the potential difference Vgs is smaller than the threshold voltage Vth, the transistor is turned off, and in principle, the drain and the source are not conducting.
However, strictly speaking, as shown in FIG. 8B, a leakage current Ids may flow from the drain to the source even in the off-operation region where the potential difference Vgs is smaller than the threshold voltage Vth. This leakage current Ids is the absolute value | Vgs | of the potential difference Vgs even when the potential difference Vgs is negative.
Increases as becomes larger.

FIG. 9 is an explanatory diagram for explaining the direction of the leakage current Ids. As shown in FIG. 9A, when the potential of the data signal Vd [n] is lower than the potential Vq, the node R corresponds to the source S (source electrode) of the writing transistor Tr and the node Q is written. This corresponds to the drain D (drain electrode) of the embedded transistor Tr. Therefore, in the case shown in FIG. 9A, the scanning signal G
A value obtained by subtracting the potential of the data signal Vd [n] from the potential of [m] becomes the potential difference Vgs, and a leakage current Ids having a magnitude corresponding to the potential difference Vgs flows from the node Q toward the node R.
Conversely, as shown in FIG. 9B, when the potential of the data signal Vd [n] is higher than the potential Vq, the node Q corresponds to the source S (source electrode) of the writing transistor Tr, and the node R
Corresponds to the drain D (drain electrode) of the write transistor Tr. For this reason, FIG.
In the case of B), the value obtained by subtracting the potential Vq from the potential of the scanning signal G [m] is the potential difference Vgs, and the leak current Ids having a magnitude corresponding to the potential difference Vgs is from the node R toward the node Q. Will flow.

FIGS. 10 and 11 show pixels a and “gray” when the electro-optical device according to the comparative example 2 displays the image shown in FIG. 4 under the same assumption as the numerical example described above. It is explanatory drawing for demonstrating the relationship between the leakage current Ids which arises in the pixel b, and the change of the display color of the pixel a and the pixel b by the said leakage current Ids.
In the following numerical examples, in addition to the preconditions in the numerical examples described above, the scanning signal G [m
] Is selected as “−10V”.

FIG. 10A shows a comparison 2 in the negative polarity period U1 when the scanning line 32 of the mc-th row is selected.
The leakage current Ids and the potential difference Vg in the pixel a when the driving circuit according to the above circuit supplies the data signal Vd [n] for displaying “black” to the pixel c by driving the pixel c to the negative polarity.
and s.
As described above, in contrast 2, the potential of the common electrode signal Vcom is kept at the potential VcomH in the negative polarity period U1. In the numerical example described above, the potential difference VCL of the pixel a displaying “gray” is “−3 V”, and the potential VcomH is “+4 V”. For this reason, the pixel a
The potential Vq at is + 1V.
On the other hand, in contrast 2, the precharge potential Vpr1 is “0 V”, which is lower than the potential Vq.
The data potential Vdt1 [n] is “−4 V”, which is lower than the potential Vq.
Therefore, in the pixel a, in the negative polarity period U1 in which the scanning line 32 of the mc-th row is selected, the node R having a lower potential than the node Q becomes the source S of the writing transistor Tr, and from the node Q toward the node R Leak current Ids flows. As a result, the potential Vq is lowered and the potential difference VCL is increased, so that the pixel a displays a black color rather than “gray” that should be displayed.
The degree to which the color displayed by the pixel a becomes black (the degree of color change) is determined based on the magnitude of the leakage current Ids, that is, the magnitude of the absolute value | Vgs | of the potential difference Vgs.

In the following, when the absolute value | Vgs | of the potential difference Vgs satisfies “0 ≦ | Vgs | ≦ 4”,
When the degree of color change of the color displayed by the pixel is “small” and “4 <| Vgs | ≦ 8” is satisfied,
When the degree of color change of the color displayed by the pixel is “medium” and “8 <| Vgs |” is satisfied, the degree of color change of the color displayed by the pixel is “large”. And only when the degree of discoloration is "large"
The discoloration may be visually recognized by the user of the electro-optical device 1.
That is, in the negative polarity period U1 in which the mc-th scanning line 32 is selected, the degree of color change (the degree of blackening) displayed by the pixel a is “large” in the period T1 and the period T2, and the period T3. Therefore, the discoloration (blackening) of the pixel a may be visually recognized in the period T1 and the period T2.

FIG. 10B shows the proportional 2 in the negative polarity period U1 when the scanning line 32 of the mc-th row is selected.
The leakage current Ids and the potential difference Vg in the pixel b when the driving circuit according to the above circuit supplies the data signal Vd [n] for displaying “black” to the pixel c by driving the pixel c with negative polarity.
and s.
Since the potential difference VCL of the pixel b displaying “gray” is “+3 V”, the potential Vq at the pixel b is “+7 V”. Therefore, in the pixel b, in the negative polarity period U1 in which the scanning line 32 of the mc-th row is selected, the node R having a lower potential than the node Q becomes the source S of the writing transistor Tr, and from the node Q toward the node R Leak current Ids flows. As a result, the potential V
Since the potential of q drops and the potential difference VCL becomes small, the pixel b displays a white color rather than “gray” which should be displayed originally.
The degree to which the color displayed by the pixel b becomes white (degree of color change) is “large” in the period T1 and the period T2 in which the potential difference Vgs is “−10 V”, and in the period T3 in which the potential difference Vgs is “−6 V”. Since it is “medium”, the discoloration (whitening) of the pixel b may be visually recognized in the period T1 and the period T2.

Thus, the discoloration (blackening) of the pixel a may be visually recognized in the periods T1 and T2, and the discoloration (whitening) of the pixel b may be visually recognized in the periods T1 and T2. Arise.
However, the degree to which the pixel a becomes black (Vgs = −10 V) and the degree to which the pixel b becomes white (Vgs =
−10V), the discoloration of the pixel a (blackening) and the discoloration of the pixel b (whitening) are canceled out, and the pixel a and the pixel b display “gray” which should be originally displayed as a whole. Will be visually recognized.

FIG. 11A shows a proportional 2 in the positive polarity period U2 in which the md-th scanning line 32 is selected.
When the driving circuit according to (1) supplies the data signal Vd [n] for displaying “black” to the pixel d by driving the pixel d to positive polarity, the leakage current Ids and the potential difference Vg in the pixel a are displayed.
and s.
As described above, in contrast 2, the potential of the common electrode signal Vcom is kept at the potential VcomL in the positive polarity period U2. Further, in the numerical example described above, the potential difference VCL of the pixel a displaying “gray” is “−3 V”, and the potential VcomL is “−4 V”. Therefore, the potential Vq at the pixel a is “−7 V”. It becomes. Therefore, in the pixel a, in the positive polarity period U2 in which the scanning line 32 of the md-th row is selected, the node Q having a lower potential than the node R becomes the source S of the writing transistor Tr and is directed from the node R to the node Q. Leak current Ids flows. This
Since the potential Vq increases and the potential difference VCL decreases, the pixel a displays a white color rather than “gray” that should be displayed.
The degree to which the color displayed by the pixel a becomes white (the degree of color change) is “small” in the period T4 to T6 in which the potential difference Vgs is “−3 V”. For this reason, the discoloration (whitening) of the pixel a occurs during the period T4 to T4.
Not visible at T6.

FIG. 11B shows the proportional 2 in the positive polarity period U2 in which the md-th scanning line 32 is selected.
When the driving circuit according to (2) supplies the data signal Vd [n] for displaying “black” to the pixel d by driving the pixel d to have a positive polarity, the leakage current Ids and the potential difference Vg in the pixel b are supplied.
and s.
Since the potential difference VCL of the pixel b displaying “gray” is “+3 V”, the potential Vq at the pixel b is “−1 V”. Therefore, in the pixel b, in the positive polarity period U2 in which the scanning line 32 of the md-th row is selected, the node Q having a lower potential than the node R becomes the source S of the writing transistor Tr and is directed from the node R to the node Q. Leak current Ids flows. As a result, the potential V
Since the potential of q rises and the potential difference VCL increases, the pixel b displays a black color rather than “gray” that should be displayed.
The degree to which the color displayed by the pixel b becomes black (the degree of discoloration) becomes “large” in all the periods T4 to T6 in which the potential difference Vgs is “−9 V”. For this reason, the discoloration (blackening) of the pixel b may be visually recognized in the periods T4 to T6.

Thus, the discoloration (whitening) of the pixel a is not visually recognized in the periods T4 to T6, and the discoloration (blackening) of the pixel b may be visually recognized in all the periods T4 to T6. That is, since the pixel b has a possibility that the discoloration (blackening) is visually recognized in all the periods (periods T4 to T6) of the one horizontal scanning period H, the discoloration of the pixel b in the entire one horizontal scanning period H. The possibility that (blackening) is visually recognized increases. Therefore, the pixel a and the pixel b as a whole are visually recognized as displaying a black color rather than “gray” which should be originally displayed.

Thus, among the pixels displaying “gray”, the pixels located in the same column as the pixels displaying “black” and supplied with the data signal Vd [n] in the positive polarity period U2 are: A black color is displayed rather than "gray" that should be displayed.
For this reason, instead of displaying an image representing a “gray” background and a “black” window as shown in FIG. 4 on the display unit 30, a “black” as shown in FIG. 12 is displayed. In the upper and lower areas of the window, an image in which vertical stripes (vertical crosstalk) of a black color is displayed rather than the original background color “gray” is displayed.
When such vertical crosstalk occurs, the image indicated by the input image data Din cannot be displayed accurately, and the display quality deteriorates.

FIGS. 13 and 14 illustrate a pixel a displaying “gray” when the electro-optical device 1 according to the present embodiment displays the image illustrated in FIG. 4 under the same assumptions as the numerical example described above. 4 is an explanatory diagram for explaining a relationship between a leak current Ids generated in the pixel b and a change in display color of the pixel a and the pixel b due to the leak current Ids.

FIG. 13A shows that, during the negative polarity period U1 in which the scanning line 32 of the mc-th row is selected, the drive circuit 20 according to the present embodiment drives the pixel c to be negative, thereby “black” with respect to the pixel c The leak current Ids and the potential difference Vgs in the pixel a when supplying the data signal Vd [n] for displaying is shown.
As described above, in the present embodiment, the potential of the common electrode signal Vcom is set to the potential VcomL in the period T1 in the negative polarity period U1, and the potential Vcom in the periods T2 and T3.
Set to H. In the numerical example described above, the potential difference VCL of the pixel a displaying “gray” is “−3”.
V ”, the potential Vq in the pixel a is“ V ”in the period T1 in the negative polarity period U1.
−7V ”, and becomes“ + 1V ”in the period T2 and the period T3.
Therefore, in the pixel a, in the negative polarity period U1 in which the mc-th scanning line 32 is selected, the period T
1, the node Q having a lower potential than the node R becomes the source S of the writing transistor Tr, and a leak current Ids flows from the node R toward the node Q. As a result, the potential Vq is increased and the potential difference VCL is reduced, so that the pixel a displays a color whiter than “gray” that should be displayed. On the contrary, in the period T2 and the period T3, the node R having a lower potential than the node Q becomes the source S of the writing transistor Tr, and the leakage current Id from the node Q toward the node R.
s flows. As a result, the potential Vq drops and the potential difference VCL increases, so that the pixel a
Displays a blacker color than “gray” which should be displayed.
The potential difference Vgs in the pixel a is “−3V” in the period T1, and “−10V” in the period T2.
”And“ −6V ”in the period T3. For this reason, among the discoloration of the pixel a, only the discoloration (blackening) in the period T2 may be visually recognized.

In FIG. 13B, in the negative polarity period U1 in which the mc-th scanning line 32 is selected, the drive circuit 20 according to the present embodiment drives the pixel c to be negative, thereby “black” with respect to the pixel c. The leakage current Ids and the potential difference Vgs in the pixel b when the data signal Vd [n] for displaying is supplied are shown.
In the numerical example described above, since the potential difference VCL of the pixel b displaying “gray” is “+3 V”, the potential Vq in the pixel b becomes “−1 V” in the period T1 in the negative polarity period U1, and the period T2 In the period T3, it becomes “+ 7V”.
Therefore, in the pixel b, the period T in the negative polarity period U1 in which the mc-th scanning line 32 is selected.
1, the node Q having a lower potential than the node R becomes the source S of the writing transistor Tr, and a leak current Ids flows from the node R toward the node Q. As a result, the potential Vq rises and the potential difference VCL increases, so that the pixel b displays a black color rather than “gray” that should be displayed. On the contrary, in the period T2 and the period T3, the node R having a lower potential than the node Q becomes the source S of the writing transistor Tr, and the leakage current Id from the node Q toward the node R.
s flows. As a result, the potential Vq drops and the potential difference VCL becomes small.
Displays a white color rather than "gray" that should be displayed.
The potential difference Vgs in the pixel b is “−9V” in the period T1, and “−10V” in the period T2.
”And“ −6V ”in the period T3. For this reason, among the discoloration of the pixel b, the discoloration (blackening) in the period T1 and the discoloration (whitening) in the period T2 may be visually recognized.

As described above, in the period T1, there is a possibility that the pixel b is visually recognized, and in the period T2, there is a possibility that the pixel a is blackened and the pixel b is whitened. In the period T2, the degree of blackening of the pixel a (Vgs = −10 V) and the degree of whitening of the pixel b (
Since Vgs = −10V), they are canceled out. As a result, only the blackening of the pixel b in the period T1 may be visually recognized. However, the period T1 is a part of the horizontal scanning period H, and it is unlikely that the blackening of the pixel b in the period T1 is visually recognized.

In FIG. 14A, in the positive polarity period U2 in which the md-th scanning line 32 is selected, the drive circuit 20 according to the present embodiment drives the pixel d in a negative polarity, thereby “black” with respect to the pixel d. The leak current Ids and the potential difference Vgs in the pixel a when supplying the data signal Vd [n] for displaying is shown.
As described above, in the present embodiment, the potential of the common electrode signal Vcom is set to the potential VcomH in the period T4 in the positive polarity period U2, and the potential Vcom in the periods T5 and T6.
Set to L. In the numerical example described above, the potential difference VCL of the pixel a displaying “gray” is “−3”.
V ”, the potential Vq at the pixel a is“ V ”in the period T4 in the positive polarity period U2.
+ 1V ", and becomes" -7V "in the period T5 and the period T6.
Therefore, in the pixel a, in the positive polarity period U2 in which the md-th scanning line 32 is selected, the period T
4, the node R having a lower potential than the node Q becomes the source S of the write transistor Tr, and a leak current Ids flows from the node Q to the node R. As a result, the potential Vq is lowered and the potential difference VCL is increased, so that the pixel a displays a black color rather than “gray” that should be displayed. On the contrary, in the period T5 and the period T6, the node Q having a lower potential than the node R becomes the source S of the writing transistor Tr, and the leakage current Id from the node R toward the node Q
s flows. As a result, the potential Vq is increased and the potential difference VCL is decreased.
Displays a white color rather than "gray" that should be displayed.
The potential difference Vgs in the pixel a is “−10V” in the period T4 and “−3V” in the period T5.
”And“ −3 V ”in the period T6. For this reason, among the discoloration of the pixel a, only the discoloration (blackening) in the period T4 may be visually recognized.

In FIG. 14B, in the positive polarity period U2 in which the scanning line 32 of the md-th row is selected, the drive circuit 20 according to the present embodiment drives the pixel d in the negative polarity so that the pixel d is “black”. The leakage current Ids and the potential difference Vgs in the pixel b when the data signal Vd [n] for displaying is supplied are shown.
In the numerical example described above, since the potential difference VCL of the pixel b displaying “gray” is “+3 V”, the potential Vq in the pixel b becomes “+7 V” in the period T4 in the positive polarity period U2, and the period T5 and It becomes “−1V” in the period T6.
Therefore, in the pixel b, in the positive polarity period U2 in which the md-th scanning line 32 is selected, the period T
4, the node R having a lower potential than the node Q becomes the source S of the write transistor Tr, and a leak current Ids flows from the node Q to the node R. As a result, the potential Vq drops and the potential difference VCL becomes small, so that the pixel b displays a color that is whiter than “gray” that should be displayed. On the contrary, in the period T5 and the period T6, the node Q having a lower potential than the node R becomes the source S of the writing transistor Tr, and the leakage current Id from the node R toward the node Q
s flows. As a result, the potential Vq is increased and the potential difference VCL is increased.
Displays a blacker color than “gray” which should be displayed.
The potential difference Vgs in the pixel b is “−10V” in the period T4 and “−9V” in the period T5.
”And“ −9V ”in the period T6. For this reason, among the discoloration of the pixel b, there is a possibility that the discoloration (whitening) in the period T4 and the discoloration (whitening) in the periods T5 and T6 will be visually recognized.

Thus, in the period T4, there is a possibility that the pixel a is blackened and the pixel b is whitened, and in the period T5 and the period T6, there is a possibility that the pixel b is blackened. Arise. In the period T4, the degree of blackening of the pixel a (Vgs = −10V) and the degree of whitening of the pixel b (Vgs = −10V) are equal to each other. As a result, only the blackening of the pixel b in the period T5 and the period T6 may be visually recognized. However, since the period T5 and the period T6 are a part of the horizontal scanning period H, the discoloration (blackening) of the pixel b is visually recognized in the entire horizontal scanning period H as in Comparative Example 2. Compared with the possibility, the possibility that the blackening of the pixel b in the period T5 and the period T6 is visually recognized is low.

Thus, in the present embodiment, the pixel b is only in a part of one horizontal scanning period H.
The discoloration (blackening) of the pixel b is merely a possibility that the discoloration (blackening) occurs. Compared with the comparative 2 having the possibility that the discoloration (blackening) of the pixel b is visually recognized in the entire horizontal scanning period H. The possibility that the discoloration (blackening) of the pixel b is visually recognized can be reduced. In other words, in the present embodiment, it is possible to reduce the possibility of occurrence of vertical crosstalk compared to the proportional 2,
Further, even if vertical crosstalk occurs, the possibility that the vertical crosstalk is visually recognized can be reduced.

<B. Second Embodiment>
In the electro-optical device 1 according to the first embodiment, the potential of the data signal Vd [n] is changed in the range of the potential VcomL or more and the potential VcomH or less.
In contrast, the second embodiment is different from the first embodiment in that the potential of the data signal Vd [n] is changed in a range including a potential smaller than the potential VcomL or a potential larger than the potential VcomH. Is different.
In the electro-optical device according to the second embodiment, the common electrode signal Vcom is set to the potential VcomH in the period T1, the common electrode signal Vcom is set to the potential VcomL in the period T4, and the precharge potential Vpr2 is set to the potential VcomL. Except that the potential is lower than
It is assumed that the configuration is the same as that of the electro-optical device 1 according to the first embodiment.

FIG. 15 illustrates a case where the electro-optical device according to the second embodiment displays the exemplary image illustrated in FIG.
The data signal Vd [n] and the common electrode signal Vcom supplied to each of the pixel c and the pixel d displaying “black”, and the voltage applied to the respective liquid crystal elements CL of the pixel c and the pixel d ( It is explanatory drawing for demonstrating the relationship with electric potential difference (VCL).
More specifically, FIG. 15 shows that the driving circuit 20 according to the second embodiment drives the pixel c in the negative polarity period U1 during which the scanning line 32 of the mc-th row is selected, and the pixel c receives data. Signal Vd
In the state in which [n] is supplied and the positive polarity period U2 in which the md-th scanning line 32 is selected,
The drive circuit 20 according to the second embodiment drives the pixel d to have a positive polarity, and the data signal Vd [
n] is an explanatory diagram showing a state of being supplied.

As shown in this figure, the power supply circuit 26 according to the second embodiment sets the common electrode signal Vcom to the potential VcomH (in this example, “+4 V”) in the negative polarity period U1, and the positive polarity period U2.
Is set to the potential VcomL (in this example, “−4 V”).
In addition, the data line driving circuit 24 according to the second embodiment sends the data signal Vd [n] to the period T1.
In the period T2, the precharge potential Vpr1 is set. In the period T3, the data potential Vdt1 [n] is set. In the periods T4 and T5, the precharge potential Vpr2 is set.
In the period T6, the data potential Vdt2 [n] is set.
In the second embodiment, the precharge potential Vpr2 is set to a potential lower than the potential VcomL. In the example shown in FIG. 15, the potential VcomH and the potential VdH are set to “+4 V”, and the potential VcomL
Is "-4V", the potential VdL is "-8V", the precharge potential Vpr1 is "0V", and the precharge potential Vpr2 is "-8V".
The example shown in FIG. 15 is the same as the numerical example described above except that the precharge potential Vpr2 and the potential VdL are “−8 V”.

As shown in FIG. 15, in the negative polarity period U1 in which the mc-th scanning line 32 is selected, the potential difference VCL in the pixel c is set to "-4V" in the period T1, and is set to "-4V" in the period T2. In the period T3, it is set to “−8V”. As a result, the potential difference VCL at the pixel c.
Is set to “−8V” and the pixel c displays “black” until the mc-th scanning line 32 is selected in the next display period F.
Further, in the positive polarity period U2 in which the md-th scanning line 32 is selected, the potential difference VCL in the pixel d is set to "-4V" in the period T4, set to "-4V" in the period T5, and the period T6. Then, “+ 8V” is set. As a result, the potential difference VCL at the pixel d is set to “+8 V”, and during the next display period F, until the md-th scanning line 32 is selected, the pixel d
Displays “black”.

Next, referring to FIG. 16, when the electro-optical device according to the second embodiment displays the image shown in FIG. 4, the leakage current Ids generated in the pixels “a” and “b” displaying “gray”.
And the change in display color of the pixels a and b due to the leak current Ids will be described.
Although illustration is omitted, in the example shown in FIG. 16, as in the case of FIGS.
The data potential Vdt1 [supplied in the negative polarity period U1 when the ma-th scanning line 32 is selected.
n] sets the potential difference VCL of the pixel a to “−3 V”, and the potential difference VCL of the pixel b by the data potential Vdt2 [n] supplied in the positive polarity period U2 in which the mb-th scanning line 32 is selected. Is set to “+3 V”, and it is assumed that the pixels a and b display “gray”.
In addition, in the negative polarity period U1 in which the mc-th scanning line 32 is selected, the drive circuit 20 according to this embodiment causes the pixel c to display “black” by driving the pixel c to the negative polarity. Since the leakage current Ids and the potential difference Vgs in the pixel a and the pixel b when the data signal Vd [n] is supplied are the same as those in the case of the proportional 2 (FIG. 10), description thereof is omitted.

In FIG. 16A, in the positive polarity period U2 in which the md-th scanning line 32 is selected, the drive circuit according to the second embodiment drives the pixel d to be positive, thereby “black” with respect to the pixel d. The leak current Ids and the potential difference Vgs in the pixel a when supplying the data signal Vd [n] for displaying is shown.
As described above, in the second embodiment, the potential of the common electrode signal Vcom is maintained at the potential VcomL in the positive polarity period U2. Further, as described above, in order to set the potential difference VCL of the pixel a displaying “gray” to “−3 V”, the potential Vq in the pixel a is “−7” in the positive polarity period U2.
V ". Therefore, in the pixel a, in the positive polarity period U2 in which the scanning line 32 of the md-th row is selected, the node R having a lower potential than the node Q becomes the source S of the writing transistor Tr in the periods T4 and T5. , Leak current Ids flows from node Q to node R. As a result, the potential Vq is lowered and the potential difference VCL is increased, so that the pixel a displays a black color rather than “gray” that should be displayed. On the contrary, in the period T 6, the node Q having a lower potential than the node R becomes the source S of the writing transistor Tr, and the leak current Ids flows from the node R toward the node Q. As a result, the potential Vq is increased and the potential difference VCL is reduced, so that the pixel a displays a color whiter than “gray” that should be displayed.
The potential difference Vgs in the pixel a is “−2V” in the period T4 and “−2V” in the period T5.
In the period T6, it is “−3V”. For this reason, the discoloration of the pixel a is not visually recognized in the periods T4 to T6.

FIG. 16B shows that, in the positive polarity period U2 in which the md-th scanning line 32 is selected, the drive circuit according to the second embodiment drives the pixel d in a negative polarity so that the pixel d is “black”. The leakage current Ids and the potential difference Vgs in the pixel b when the data signal Vd [n] for displaying is supplied are shown.
As described above, in the example shown in this figure, the potential difference VCL of the pixel b displaying “gray” is set to “+3”.
Therefore, in the positive polarity period U2, the potential Vq at the pixel b is “−1V”.
Therefore, in the pixel b, in the positive polarity period U2 in which the md-th scanning line 32 is selected, the period T
4 and the period T5, the node R having a lower potential than the node Q becomes the source S of the writing transistor Tr, and a leak current Ids flows from the node Q to the node R. This
Since the potential Vq drops and the potential difference VCL becomes small, the pixel b displays a color that is whiter than “gray” that should be displayed. On the other hand, in the period T6, the node Q having a lower potential than the node R is used.
Becomes the source S of the write transistor Tr, and a leak current Ids flows from the node R to the node Q. As a result, the potential Vq rises and the potential difference VCL increases, so that the pixel b displays a black color rather than “gray” that should be displayed.
The potential difference Vgs in the pixel b is “−2V” in the period T4 and “−2V” in the period T5.
In the period T6, it is “−9V”. For this reason, among the discoloration of the pixel b, only the discoloration (blackening) in the period T6 may be visually recognized.

As described above, in the second embodiment, only the discoloration (blackening) of the pixel b in the period T6 may be visually recognized. However, since the period T6 is a part of the horizontal scanning period H, there is a possibility that the discoloration (blackening) of the pixel b is visually recognized in one horizontal scanning period H as in Comparative Example 2. When compared with the case of having the pixel b, the possibility that the blackening of the pixel b in the period T5 and the period T6 is visually recognized is low.

As described above, in the second embodiment, since there is only a possibility that the discoloration (blackening) of the pixel b is visible only in a part of the one horizontal scanning period H, the one horizontal scanning period H
Compared with the proportional 2 which has a possibility that the discoloration (blackening) of the pixel b is visually recognized as a whole,
The possibility that the discoloration (blackening) of the pixel b is visually recognized can be reduced. In other words, the second
In the embodiment, the possibility of occurrence of vertical crosstalk can be reduced as compared with the comparative example 2, and even if vertical crosstalk occurs, the vertical crosstalk can be visually recognized. Can be kept low.

In the second embodiment, for example, in the numerical example described above, the potential difference VCL is set to “−8V” by changing the potential of the data signal Vd [n] with a width of 12V from “−8V” to “+ 4V”.
It can be changed with a width of 16V of ~ + 8V.
That is, the electro-optical device according to the second embodiment can suppress the change width of the potential of the data signal Vd [n] with respect to the change width of the potential difference VCL, as compared with the comparative 1. For this reason, the electro-optical device according to the second embodiment can suppress the driving capability of the data line driving circuit 24 to be lower than that of the comparative 1 and the potential fluctuation of the data line 34 propagates to the node Q and the like. It is possible to suppress deterioration in display image quality caused by doing so.

<C. Modification>
Each of the above forms can be variously modified. Specific modifications are exemplified below. Two or more aspects arbitrarily selected from the following examples can be appropriately combined within a range that does not contradict each other.

<Modification 1>
In the first embodiment described above, the display period F in which the first horizontal scanning period H is the negative polarity period U1.
And the display period F in which the first horizontal scanning period H is the positive polarity period U2 exists, but the present invention is not limited to such a mode. For example, the first display period F in the first embodiment The horizontal scanning period H may be fixedly assigned to either the negative polarity period U1 or the positive polarity period U2.
Even in this case, since the polarity of the potential difference VCL is inverted between the period T1 and the period T2 of the negative polarity period U1 and between the period T4 and the period T5 of the positive polarity period U2, the image sticking occurs in the liquid crystal element CL. Can be suppressed.

<Modification 2>
In the first embodiment and the modification described above, negative polarity driving is performed in the negative polarity period U1, and positive polarity driving is performed in the positive polarity period U2, but this is only an example, and positive polarity driving is performed in the negative polarity period U1. However, negative polarity driving may be performed in the positive polarity period U2.
That is, in the power supply circuit 26, the potential of the common electrode signal Vcom in the period T1 (or T4) and the potential of the common electrode signal Vcom in the period T2 (or T5) are based on the precharge potential Vpr1 (or Vpr2). What is necessary is just to set the electric potential of the common electrode signal Vcom so that it may become a reverse polarity.
In this case, the data line driving circuit 24 uses the data potential Vdt1 in the period T3 (or T6).
[N] (or Vdt2 [n]) is a precharge potential Vpr1 (or Vpr2) in the period T2 (or T5) with reference to the potential of the common electrode signal Vcom in the period T2 (or T5).
It is preferable to set the potential of the data signal Vd [n] so as to have the same polarity.

<Modification 3>
In the embodiment and the modification described above, the polarity of the polarity signal Pol is inverted every display period F and the polarity is inverted every horizontal scanning period H, but the present invention is limited to the above-described mode. It is not a thing.
For example, the polarity may be inverted every a plurality of display periods F, or the polarity may be inverted every a plurality of horizontal scanning periods H. Specifically, in a certain display period F, the first horizontal scanning period H and the second horizontal scanning period H are defined as a negative polarity period U1,
The polarity may be switched every two horizontal scanning periods H, such that the third horizontal scanning period H and the fourth horizontal scanning period H are set as the positive polarity period U2. In this case, since the cycle of polarity inversion can be made longer than in the above-described embodiment, the number of changes in the polarity of the potential of the data line 34 can be reduced, and the degree of deterioration in image quality can be suppressed to a low level. It becomes possible.
In this specification, the allocation of each horizontal scanning period H to the negative polarity period U1 or the positive polarity period U2 is performed based on the polarity signal Pol, but this aspect is merely an example.
The allocation of each horizontal scanning period H to the negative polarity period U1 or the positive polarity period U2 may be performed by any method. For example, a counter that counts the number of times the horizontal synchronization signal Hsnc becomes active may be provided, and each horizontal scanning period H may be assigned to the negative polarity period U1 or the positive polarity period U2 based on the count value of the counter.

<Modification 4>
In the embodiment and the modification described above, for example, as shown in FIG. 3, the negative polarity period U1 is equal to the period T1.
The negative period U1 may include a period other than the periods T1 to T3. In other words, the period T1 starts after the start of the negative polarity period U1, the period T2 starts after the end of the period T1, the period T3 starts after the end of the period T2, and the negative polarity The period U1 may end after the end of the period T3. Similarly, the positive polarity period U2 may include a period other than the periods T4 to T6.

<Modification 5>
In the embodiment and the modification described above, the scanning line driving circuit 22 scans the m-th row or the entire negative period U1 in which the m-th scanning line 32 is selected, for example, as shown in FIG. The scanning signal G [m] is set to a predetermined selection potential in the entire positive period U2 during which the line 32 is selected. However, the present invention is not limited to the above-described mode, and the m-th row. Scan line 3
In the period T3 in the negative polarity period U1 in which 2 is selected or in the period T6 in the positive polarity period U2 in which the m-th row scanning line 32 is selected, the scanning signal G [m] is set to a predetermined selection potential. It may be set.
In this case, a precharge potential cannot be supplied to the pixel electrode 42.
Since a precharge potential can be supplied to the data line 34, writing of the data potential to the pixel can be facilitated.

<Modification 6>
In the embodiment and the modification described above, the data line driving circuit 24 supplies the data potential to the data line 34 in the nth column in the entire period T3 or the entire period T6, for example, as shown in FIG. However, the present invention is not limited to such an embodiment. For example, the period T
3 or the period T6 is divided into N, and the data lines 34 in the first column to the Nth column are divided for each divided period.
The data potential may be supplied in order. In addition, a plurality of N data lines are divided into a predetermined number of sets, and the period T3 or the period T6 is divided into a predetermined number. For each divided period, data is supplied to each set of data lines 34. A potential may be supplied.

<Modification 7>
In the embodiment and the modification described above, the write transistor Tr is an N-channel transistor, but may be a P-channel transistor.

<D. Application example>
The electro-optical device 1 exemplified in the above embodiments can be used in various electronic apparatuses.
17 to 19 exemplify specific forms of electronic devices that employ the electro-optical device 1.

FIG. 17 shows a projection display device (three-plate projector) 40 to which the electro-optical device 1 is applied.
FIG. The projection display device 4000 has different display colors (red, green, blue).
The three electro-optical devices 1 (10R, 10G, 10B) corresponding to The illumination optical system 4001 supplies the red component r of the light emitted from the illumination device (light source) 4002 to the electro-optical device 1R, the green component g to the electro-optical device 1G, and the blue component b to the electro-optical device 1B.
To supply. Each electro-optical device 1 functions as a light modulator (light valve) that modulates each monochromatic light supplied from the illumination optical system 4001 in accordance with a display image. The projection optical system 4003 is
The emitted light from each electro-optical device 1 is synthesized and projected onto the projection surface 4004. An observer visually recognizes an image projected on the projection surface 4004.

FIG. 18 is a perspective view of a portable personal computer that employs the electro-optical device 1. The personal computer 2000 includes an electro-optical device 1 that displays various images, and a main body 2010 on which a power switch 2001 and a keyboard 2002 are installed.

FIG. 19 is a perspective view of a mobile phone to which the electro-optical device 1 is applied. Cell phone 3000
Includes a plurality of operation buttons 3001, scroll buttons 3002, and the electro-optical device 1 for displaying various images. 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 according to the invention is applied include the devices exemplified in FIGS. 17 to 19, personal digital assistants (PDAs), digital still cameras, televisions, video cameras, Car navigation devices, in-vehicle displays (instrument panels), electronic notebooks, electronic paper, calculators, word processors, workstations, videophones, POS terminals, printers, scanners, copiers, video players, devices with touch panels, etc. Can be mentioned.

DESCRIPTION OF SYMBOLS 1 ... Electro-optical device, 10 ... Electro-optical panel, 20 ... Drive circuit, 22 ... Scan line drive circuit, 24 ... Data line drive circuit, 26 ... Power supply circuit, 30 ... Display part, 32 ......
Scan line, 34... Data line, 50... Display control circuit, PX ... pixel circuit, CL ... liquid crystal element, Tr ... writing transistor.

Claims (4)

Data lines,
A plurality of scan lines intersecting the data lines;
A plurality of pixels provided corresponding to intersections of the data lines and the plurality of scanning lines and having a writing transistor;
A scanning line driver that sequentially sets a selection potential to each of the plurality of scanning lines and sets a non-selection potential when the selection potential is not set and supplies the non-selection potential to the gate of the write transistor;
A data signal supply unit for supplying a data signal to the data line;
An electrode signal supply unit for supplying an electrode signal to the first electrode;
With
The pixel is
A liquid crystal element including a liquid crystal provided between the first electrode, the second electrode connected to the writing transistor, and the first electrode and the second electrode;
The data signal supply unit
Of the first unit period for setting the selection potential on the scanning line, the potential of the data signal is set to a first precharge potential in a first period and a second period following the first period,
Among the first unit periods, in a third period subsequent to the second period, a pixel provided with the potential of the data signal corresponding to a scan line selected by the scan line driver in the first unit period Set the first data potential to specify the gradation to be displayed,
Of the second unit period in which the selection potential is set for the other scanning lines following the first unit period, the potential of the data signal in the fourth period and the fifth period following the fourth period. Is set to the second precharge potential,
Among the second unit periods, in a sixth period subsequent to the fifth period, a pixel provided with the potential of the data signal corresponding to the scanning line selected by the scanning line driver in the second unit period Set the second data potential to specify the gradation to be displayed,
The electrode signal supply unit
In the first period and the fifth period, the potential of the electrode signal is set to a first potential that is closer to the non-selection potential of the scanning signal than the first precharge potential and the second precharge potential,
In the second period and the fourth period, the potential of the electrode signal is set to a second potential that is farther from the non-selection potential than the first precharge potential and the second precharge potential.
An electro-optical device. The electrode signal supply unit
In the third period, the potential of the electrode signal is set to the second potential,
In the sixth period, the potential of the electrode signal is set to the first potential,
The first data potential is
Closer to the non-selection potential than the second potential;
The second data potential is
More away from the non-selection potential than the first potential,
The electro-optical device according to claim 1.   An electronic apparatus comprising the electro-optical device according to claim 1. A pixel comprising: a first electrode; a second electrode; a liquid crystal element including a liquid crystal provided between the first electrode and the second electrode; and a writing transistor connected to the second electrode;
An electro-optical device control method comprising:
Sets the selection potential to the gate of the write transistor between the unit period, to the period is not set the selection potential to set the non-selection potential to the gate of the writing transistor,
Between the first unit period between the unit period has a first period, a second period and a third period,
In the first period, the potential of the electrode signal supplied to the first electrode is set to the first potential, the potential of the data signal supplied to the second electrode is set to the precharge potential,
In a second period subsequent to the first period, the potential of the electrode signal is set to a second potential having a polarity opposite to the first potential with respect to the precharge potential, and the potential of the data signal is set to Set to the precharge potential,
In a third period subsequent to the second period, the potential of the electrode signal is set to the second potential, the potential of the data signal is set to a data potential that specifies a gradation to be displayed by the pixel,
The second unit period is between the unit period subsequent to said first unit period has a fourth period, the fifth period and the sixth period,
In the fourth period, it sets the potential of the electrode signal to said second potential, setting the potential of the data signal to the precharge potential,
In the fifth period subsequent to the fourth time period, it sets the potential of the electrode signal to said first potential, setting the potential of the data signal to the precharge potential,
In a sixth period subsequent to the fifth period, the potential of the electrode signal is set to the first potential, and the potential of the data signal is set to a data potential for designating a gradation displayed by the pixel.
A control method for an electro-optical device.

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