JP2003316329A - Liquid crystal display device and its driving method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a liquid crystal display device in which reduction of display quality due to optical leakage currents is prevented, and its driving method. <P>SOLUTION: The liquid crystal display device is provided with a plurality of signal lines 11 which transmit a display signal, a plurality of pixel electrodes 4 which are arranged in a matrix shape corresponding to pixels and a plurality of TFT 1 (thin film transistors 1), each source electrode (S) of whose source electrodes and each drain electrode (D) of whose drain electrodes are connected respectively to the signal line 11 and a corresponding pixel electrode 4. A correction signal generating circuit 15 supplies a correction signal for generating an inverse optical leakage current which has a polarity opposite to that of an optical leakage current to be generated between the signal line 11 and the corresponding pixel electrode 4 to each pixel electrode 4 via a correction signal line 13 and a corresponding TFT 2. <P>COPYRIGHT: (C)2004,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a liquid crystal display device capable of reducing the influence of light leakage current on display and a driving method thereof.

[0002]

2. Description of the Related Art An active matrix type liquid crystal display device includes two glass substrates and a liquid crystal sandwiched between the glass substrates.

Then, by applying a display signal voltage (display signal voltage) between the pixel electrode on one substrate and the counter electrode on the other substrate facing the pixel electrode, the alignment state of the liquid crystal is changed. Then, the display is performed by controlling the amount of light transmitted through the liquid crystal.

A switching element is provided on the substrate in order to apply the display signal so as to correspond to the image to be displayed.

As the switching element, a non-linear element such as a diode is used in addition to a thin film transistor (TFT). Above all, a polysilicon TFT, which can be integrally formed with a drive circuit of a liquid crystal display device and has a high response speed, is usually used.

However, in the active matrix type liquid crystal display device as described above, when the TFT, which is a switching element, is irradiated with light, electrons and holes are formed in the depletion layer portion of the pn junction (pn diffusion junction). A pair of
A current (light leak current) flows between the source electrode (S) and the drain electrode (D) in the FT.

For this reason, even when the TFT is turned off, a light leak current is generated, which causes crosstalk and contrast reduction. Further, when the amount of light leakage current of each TFT varies due to the difference in the diffusion state of each TFT, unevenness in light and shade on the liquid crystal display occurs, and the display quality is deteriorated.

In order to solve this problem, for example, Japanese Patent Laid-Open No. 58-171860 discloses a switching element connected in series in a liquid crystal display device.

As a result, the source-drain voltage applied to the switching element is reduced, and the light leakage current is reduced by the amount of the source-drain voltage reduction.

However, in the structure of this switching element, the diffusion length (the length of the diffusion junction portion) is longer than the length of the depletion layer portion, as in the case of a polysilicon TFT.
And if the area and length of the diffusion junction are constant (that is, the diffusion length is constant regardless of the source-drain voltage),
The light leakage current does not depend on the source-drain voltage. Therefore, it becomes difficult to reduce the light leak current.

Here, the relationship between the source-drain voltage of the TFT and the generated light leak current is shown in the graph of FIG. Here, bright (maximum) indicates the light leak current when the irradiation light amount is 770,000 lx, and bright (intermediate) indicates the light leakage current when the irradiation light amount is 330,000 lx.

As shown in the figure, the light leak current gradually increases until the absolute value of the source-drain voltage reaches about 0.4V. On the other hand, when the absolute value of the source-drain voltage is 0.4 or more, the photoleakage current is almost saturated, and the photoleakage current does not depend on the source-drain voltage.

That is, when the absolute value of the source-drain voltage is a constant value (0.4 V in this case) or more, the light-leakage current is constant regardless of the bias condition for the source-drain voltage. Becomes

Therefore, the light leak current is caused by the source of the TFT.
As a liquid crystal display device capable of reducing (reducing) the light leak current even when it does not depend on the drain voltage, Japanese Patent Laid-Open No. Hei 10-221675 discloses a liquid crystal display device which does not perform scanning in a still screen state. Is listed.

This liquid crystal display device discriminates a moving image or a still image on the display screen, and in the still screen state, the switching element is always turned off, and the potential (voltage) of the signal line at that time is changed to that of the pixel electrode. Invert with respect to the potential (reverse drive). That is, the potential of the signal line is set to the opposite polarity (negative polarity / positive polarity) to the positive polarity / negative polarity of the pixel electrode.

As a result, a current reverse to the generated light leakage current (reverse light leakage current) can be passed. Therefore,
Since the light leak current can be invalidated (cancelled), the potential fluctuation of the pixel electrode is less likely to occur.

Further, Japanese Patent Laid-Open No. 2000-180899 discloses a liquid crystal display device having two light shielding films.

This liquid crystal display device, as shown in FIG.
In a liquid crystal display device having a layered structure, a channel portion 202 located below a gate electrode 201 of a switching element (TFT) is sandwiched between an upper light shielding layer 203 and a tapered lower light shielding layer 204.

Therefore, the light irradiation amount to the channel portion 202 can be reduced, and the light leak current generated in the TFT can be reduced.

Thus, even if the absolute value of the source-drain voltage in the TFT is a certain value or more and the light-leakage current does not depend on the source-drain voltage of the TFT, the light-leakage current can be reduced. You can

[0021]

However, in the liquid crystal display device described in JP-A-10-221675,
For example, when only a part of the personal computer display screen is in the moving image state and most of the other screen (pixel) states are the still image state (still screen state), the effect of reducing the light leak current is reduced.

Therefore, it is difficult to prevent display quality deterioration such as display unevenness in a certain display screen area.

Here, for example, in FIG.
In the liquid crystal display device described in Japanese Patent No. 21675, the relationship between the applied voltage (liquid crystal applied voltage) to the liquid crystal when displaying a moving image and the transmittance / display unevenness is shown. In this figure, the above relationship is obtained in a normally white mode liquid crystal display device.

For example, in a certain pixel, the switching element writes the positive (+ polarity) display data to the pixel electrode (pixel). At this time, because of the inversion driving, negative polarity (-polarity) data (-polarity data) exists in the signal line for a certain period T (for example, in the case of the inversion driving of one horizontal line, about 1/2 frame period). It is like this.

Then, a photo-leakage current flows through the pixel electrode having the potential of the initial writing state (the potential of the initial pixel electrode) through the switching element for a certain period, and the potential of the pixel electrode is on the negative side (white). Level side).

The change amount ΔVlc of the voltage of the pixel electrode (pixel voltage) at this time is the pixel capacitance Clc (liquid crystal + auxiliary capacitance).
And the light leakage current I, the following expression (1) ΔVlc = (I × T) / Clc (1) is satisfied.

Furthermore, when the display data of the signal line returns to the positive polarity, the variation amount ΔVlc of the pixel voltage is
It becomes the voltage difference between both ends.

However, since the difference voltage is very small,
As a result, only the change due to the-polarity data is added.

Here, based on the measurement example of the light leakage current shown in FIG. 6 [the light leakage current is about 3 pA when the source-drain voltage is 2 V, the pixel capacitance Clc (liquid crystal + auxiliary capacitance)).
Is 50 fF, the frame frequency is 60 Hz (frame cycle: about 16 ms), and the liquid crystal applied voltage (difference between the pixel electrode and the counter electrode) is ± 1 V on the whole display, the voltage (pixel voltage) +1 V is applied to a certain pixel electrode. Then, the light leakage current I
When the effect of ΔVlc is calculated from the above equation (1), it is 1
The decrease amount ΔVlc (−) of the inversion drive voltage (−1V) in the frame period is expressed by the following equation (2).

ΔVlc (−) = (3 [pA] × 16 [ms] / 2) / 50 [fF] = 480 [mV] (2) When the liquid crystal applied voltage is + 1V, which is the same as the pixel voltage,
A light leak current is generated in a direction to alleviate the decrease ΔVlc (−).

However, as can be seen from the measurement example of the light leakage current shown in FIG. 6 (see bright (maximum)), the light leakage current is in the linear region (the region where the light leakage current is saturated), and the above equation is used. The average light leakage current between 480 mV and 0 mV obtained in 2 is about 1.5 pA.

The relaxation amount ΔVlc (+) is expressed by the following equation (3).

ΔVlc (+) = (1.5 [pA] × 16 [ms] / 2) / 50 [fF] = 240 [mV] (3) As a result, there is a decrease due to the light leak current during the inversion drive. The total effect of both tendencies of relaxation is obtained from the difference, and is given by the following equation (4). ΔVlc = ΔVlc (+) − ΔVlc (−) = 240 [mV] −480 [mV] = − 240 [mV] (4) That is, when the liquid crystal applied voltage is 1V, the change amount Δ
Vlc (-240 mV) is generated, and the transmittance of 88% at 1 V (point A) changes to 94% (point B) after one frame period, which causes deterioration of display quality.

Even when the negative polarity display data is written to the pixel electrode, the change in the pixel voltage shows the same change except that the polarity is reversed.

Similarly to a normally white mode display device which changes to the white side (liquid crystal applied voltage "0V" side), a normally black mode display device has a black side (liquid crystal applied voltage "0V" side). Side). That is, in both cases, the applied voltage to the pixel shows a change to the 0V side.

On the other hand, in the liquid crystal display device described in Japanese Unexamined Patent Publication No. 2000-180899, even if the amount of light applied to the TFT in the liquid crystal display device is reduced, the light passing through the part where the light shielding film is not formed is still visible. In some cases, the light may be reflected by a portion formed outside the liquid crystal display device (for example, a lens, a polarizing plate, a mirror in a projection) or an inner wall of the liquid crystal display device and may return to the TFT side.

Particularly when used in a transmission type projection display device, very strong light is applied to the liquid crystal panel surface in order to enlarge and project an image using a small liquid crystal panel.

Therefore, in addition to direct incident light, the amount of light (reflected light) returning on the TFT side is large, and no matter how much light is shielded, the light leak current of the TFT will be affected by the scattered light. However, there is a problem in that the display quality is adversely affected.

The present invention has been made in view of the above problems, and an object of the present invention is to provide a liquid crystal display device and a method for driving the liquid crystal display device, which prevent deterioration of display quality due to light leakage current.

[0040]

In order to solve the above-mentioned problems, a liquid crystal display device of the present invention includes a signal line for transmitting a display signal, pixel electrodes arranged in a matrix corresponding to pixels, In a liquid crystal display device including a transistor in which a source electrode is connected to the signal line and a drain electrode is connected to the pixel electrode, a reverse light leakage current having a polarity opposite to that of the light leakage current generated between the signal line and the pixel electrode. Is provided with a correction signal supply means for supplying a correction signal for generating

Normally, when a transistor is irradiated with light,
A pair of electrons and holes is generated in the depletion layer portion of the pn junction (pn diffusion junction) of the transistor, and light leakage occurs between the source electrode and the drain electrode of the TFT, that is, between the pixel electrode and the signal line. Electric current is generated.

However, according to the above configuration, for example, when the display signal is not being supplied to the pixel electrode (when not being written in the pixel), that is, through the pixel electrode, for example, the liquid crystal / storage capacitor is displayed. By supplying the correction signal to the pixel electrode after the signal is stored, a reverse light leak current having a polarity opposite to that of the light leak current is generated in the pixel electrode.

Therefore, the generated light leak current and the reverse light leak current cancel each other out, and the light leak current becomes invalid. As a result, it is possible to prevent the display quality from deteriorating due to the light leak current, and it is possible to provide a liquid crystal display device having a good display quality.

Further, it is possible to prevent the deterioration of the display quality of the liquid crystal display device due to the light leak current with a simple structure without providing a light shielding film for blocking the light incident on the switching element inside the liquid crystal display device. You can

In the above liquid crystal display device, it is preferable that the correction signal is a signal having the same period as the display signal and a polarity opposite to that of the display signal.

According to the above configuration, for example, when the display signal oscillating at a constant cycle (for example, every horizontal line) is supplied to the signal line, the signal line and the pixel electrode are generated at the constant cycle. The reverse light leak current can be generated immediately after the occurrence of the light leak current during the period.

Therefore, for example, the voltage (voltage of the liquid crystal / storage capacity) between the pixel electrode and the counter electrode facing the pixel electrode repeats a slight increase / decrease around the initial writing voltage, The fluctuation can be reduced on average. As a result, it is possible to further prevent the deterioration of the display quality of the liquid crystal display device due to the light leakage current.

In the above liquid crystal display device, it is preferable that the correction signal is a signal having a period equal to or longer than the frame period and a polarity opposite to that of the display signal.

Normally, the fluctuation in the potential of the pixel electrode, which changes due to the supply of the correction signal (light leak current and reverse light leak current), appears to the human eye as a flicker phenomenon when the magnitude thereof changes to a certain extent.

However, according to the above configuration, by setting the cycle of the correction signal to be the frame cycle (generally 1/60 seconds) or more, the potential fluctuation of the pixel electrode due to the correction signal can be suppressed. Therefore, the flicker phenomenon can be prevented from being visually recognized, and the display quality of the liquid crystal display device can be improved.

In the above liquid crystal display device, it is preferable that the amplitude of the correction signal is larger than the amplitude of the display signal.

Usually, for example, when a display signal (black level display signal or white level display signal) for making a display screen of a liquid crystal display device black display or white display is supplied to the pixel electrode, the signal line and the pixel are Since the potential difference between the electrodes is large, the light leak current also has a large value. In particular, the light leak current in this case is in a saturated state (saturated current value).

However, according to the above configuration, the amplitude of the correction signal is larger than the amplitude of the display signal, that is, the voltage value of the correction signal is smaller than the difference between the voltage applied to the pixel electrode and the voltage of the display signal. The difference between the voltage applied to the pixel electrode and the voltage of the correction signal is set to be large.

As a result, even if the light leak current has a large value, that is, the light leak current having a saturated current value, the reverse light leak current generated by the correction signal is
It becomes a current value (saturated current value) that is approximately the same as the light leakage current, and cancellation is possible.

Therefore, it is possible to more reliably cancel the light leak current and the reverse light leak current, and it is possible to prevent deterioration of the display quality of the liquid crystal display device.

In the above-described liquid crystal display device, the correction signal supply means is set to a predetermined value based on the clock signal for measuring the scanning timing, which is supplied to the transistor from the gate driver for line-sequentially selecting and scanning the pixels. It is preferable to control the inversion cycle of the correction signal in which the polarity of the voltage is inverted every period.

According to the above configuration, by controlling the inversion cycle of the correction signal by using the clock signal, the inversion cycle can be used as the display signal without newly providing a circuit for measuring the scanning timing. Can be the same.

In the liquid crystal display device of the present invention, signal lines for transmitting a display signal, pixel electrodes arranged in a matrix corresponding to pixels, source electrodes to the signal lines, and drain electrodes to the pixel electrodes are connected. In the liquid crystal display device including the transistor, the light leak current generated between the signal line and the pixel electrode has a reverse polarity, and a reverse light leak current that cancels the light leak current is applied to the pixel electrode. It is characterized in that a reverse current generating means for generating the reverse current is provided.

According to the above-mentioned structure, for example, when the display signal is not supplied to the pixel electrode, the counter light leak current is generated in the pixel electrode, so that the generated light leak current and the counter light leakage current cancel each other. Becomes As a result, it is possible to prevent the display quality from deteriorating due to the light leak current, and it is possible to provide a liquid crystal display device having a good display quality.

Further, it is possible to prevent deterioration of the display quality of the liquid crystal display device due to light leakage current with a simple structure without providing a light shielding film or the like for blocking the light incident on the switching element inside the liquid crystal display device. You can

In order to solve the above problems, the driving method of the liquid crystal display device of the present invention is a transistor in which a scanning line is connected to the gate electrode, a pixel electrode is connected to the drain electrode, and a signal line is connected to the source electrode. In the driving method of the liquid crystal display device, which supplies the display signal transmitted by the signal line to the pixel electrode when the scanning signal transmitted by the scanning line is turned on, the signal line and the pixel electrode A correction signal for generating a reverse light leak current having a polarity opposite to that of the light leak current generated between the pixel electrode and the display signal is not supplied to the pixel electrode by the transistor. It is characterized in that it is supplied to the pixel electrode.

According to the above method, when the display signal is not supplied to the pixel electrode (when it is not written in the pixel), that is, the display signal is stored in the liquid crystal / storage capacitor via the pixel electrode. After that, by supplying the correction signal to the pixel electrode, a reverse light leak current having a polarity opposite to that of the light leak current is generated in the pixel electrode.

Therefore, the generated light leak current and the reverse light leak current cancel each other out, and the light leak current becomes invalid. As a result, it is possible to prevent the display quality from deteriorating due to the light leak current.

Further, it is possible to prevent the deterioration of the display quality due to the light leakage current with a simple structure without providing a light-shielding film for shielding the light incident on the switching element inside the liquid crystal display device.

In the liquid crystal display device driving method described above, it is preferable that the correction signal is a signal having the same period as the display signal and a polarity opposite to that of the display signal.

According to the above method, for example, when a display signal that oscillates in a constant cycle (for example, every horizontal line) is supplied to the signal line, the signal line and the pixel electrode generated in the constant cycle are generated. The reverse light leak current can be generated immediately after the occurrence of the light leak current during the period.

Therefore, for example, the voltage between the pixel electrode and the counter electrode facing the pixel electrode repeats a slight increase or decrease around the initial write voltage, and the voltage fluctuation can be reduced on average. As a result, it is possible to further prevent the display quality of the liquid crystal display device from being deteriorated due to the light leakage current.

In the driving method of the liquid crystal display device described above, it is preferable that the correction signal is a signal having a period of a frame period or more and a polarity opposite to that of the display signal.

According to the above method, by making the cycle of the correction signal equal to or longer than the frame cycle, it is possible to suppress the potential fluctuation of the pixel electrode due to the correction signal. Therefore, it is possible to prevent the flicker phenomenon from being visually recognized, and it is possible to improve the display quality of the liquid crystal display device, for example.

In the above method of driving the liquid crystal display device, it is preferable that the amplitude of the correction signal is set to be larger than the amplitude of the display signal.

According to the above method, the amplitude of the correction signal becomes larger than the amplitude of the display signal, that is, the voltage value of the correction signal is smaller than the difference between the voltage applied to the pixel electrode and the voltage of the display signal. The difference between the voltage applied to the electrodes and the voltage of the correction signal is set to be large.

As a result, even if the light leak current has a large value, that is, the light leak current has a saturated current value,
The reverse light leak current generated by the correction signal has a current value (saturated current value) similar to that of the light leak current,
Offsetting is possible. That is, the light leak current can be invalidated.

Therefore, the light leak current and the reverse light leak current can be more surely canceled, and for example, a liquid crystal display device having a good display quality can be provided.

In the above method of driving the liquid crystal display device, it is preferable that the correction signal is supplied to the pixel electrode when the display of the liquid crystal display device represents the halftone level.

In general, the display change of the liquid crystal display device due to the potential change of the pixel electrode often appears remarkably in the display at the halftone level due to the visual characteristics. That is, the display of the halftone level is more likely to be affected by the display unevenness, for example, than the display of the extreme white level or the black level.

However, according to the above method, the cancellation of the light leak current using the correction signal is performed when the display of the liquid crystal display device represents the halftone level,
The display quality of the liquid crystal display device can be most effectively improved.

When a correction signal is supplied in such a halftone level display, the amplitude of the correction signal is
The amplitude may be smaller than the amplitude of the correction signal supplied in displaying the black level or the white level.

This is because the potential of the pixel electrode is a halftone level potential and is smaller than the potential at the black level or the white level, so that the amplitude of the correction signal is smaller than that in the case of displaying the black level or the white level. Even in this case, it is possible to sufficiently prevent the deterioration of the display quality.

[0079]

BEST MODE FOR CARRYING OUT THE INVENTION An embodiment of the present invention will be described below with reference to FIGS. 1 to 6.

The liquid crystal display device of this embodiment includes an active matrix substrate in which pixels are arranged in a matrix.

As shown in FIG. 1, a thin film transistor (hereinafter, referred to as TFT: Thin F) is formed on the active matrix substrate.
1 and 2, pixel electrodes 4, signal lines 11, scanning lines 12, and correction signal lines 13 are arranged.

Further, the source driver 21 connected to the signal line 11 for generating a display signal (data signal) and the scanning line 12
There is provided a gate driver 22 which is connected to the control signal generator 13 and generates a scanning signal, and a correction signal generation circuit 15 (correction signal supply means, reverse current generation means) which is connected to the correction signal line 13 and generates a correction signal. The correction signal from the correction signal generation circuit 15 will be described later in detail.

Further, a counter substrate (not shown) is arranged to face the active matrix substrate with the liquid crystal layer 6 interposed therebetween. The counter electrode 14 is disposed on the surface of the counter substrate facing the active matrix substrate. An image is displayed by changing the orientation of the liquid crystal by applying a voltage according to image data between the counter electrode 14 and each pixel electrode 4 corresponding thereto.

A storage capacitor (auxiliary capacitor) 5 and a liquid crystal layer 6 are arranged (connected) between the pixel electrode 4 and the counter electrode 14 arranged so as to face the pixel electrode 4.

The pixel electrodes 4 ... Are arranged in a matrix. That is, the pixel electrodes 4 are arranged corresponding to the respective pixels. A drain electrode (D) of the TFT 1 which is a switching element for selectively driving each pixel electrode 4 is connected to the pixel electrode 4. A scanning line (gate line) 12 is connected to the gate electrode (G) of each TFT 1, and a signal line (source line) 11 is connected to the source electrode (S). That is, the TFT 1 is a switching element whose source is connected to the signal line 11 and whose drain is connected to the pixel electrode 4.

The signal lines 11 and the scanning lines 12 are arranged around the pixel electrodes 4 arranged in a matrix so as to be orthogonal to each other. The scanning line 12 inputs a gate signal (scanning signal) for driving and controlling the pixel electrode 4 to the pixel electrode 4. When the TFT1 is driven (when the TFT1 is turned on), the display signal is T
It is input to the pixel electrode 4 via the FT1.

The correction signal line 13 is arranged in parallel with the scanning line 12 and is connected to the source electrode (S) of each TFT 2. In the TFT 2, the drain electrode (D) is connected to the pixel electrode 4, the gate electrode (G) is connected to the ground (Lo output voltage level of the gate driver 22), and the source electrode (S) is connected to the correction signal line 13. The TFT 2 is always off.

The storage capacitor 5 is added to each pixel electrode 4 and holds the charge of the pixel electrode 4 to stabilize the pixel potential.

Here, the driving principle of the liquid crystal will be described. The scanning lines 12 are scanning lines G1, G2, G3 ... Gn.
Of n (n: integer).

In order to display a screen, the liquid crystal display device has
The time-divided display data is displayed on the scanning lines G1, G2, G3 ...
Sequential scanning is performed along Gn.

For example, when the scanning line G1 is horizontally scanned,
A gate voltage for turning on the TFT 1 is applied (scanning signal is supplied) to the scanning line G1. At this time, a gate voltage (scanning signal is supplied) for turning off the TFT 1 is applied to the other scanning lines G2, G3 ... Gn.

Thus, when the scanning line G1 is horizontally scanned, the TFT1 of only the scanning line G1 is turned on,
The signal voltage (display signal) applied to the signal line 11 is T
Scanning line G from the source electrode of FT1 through the drain electrode
1 to the pixel electrode 4.

At this time, the charges given to the pixel electrode 4 are accumulated in the storage capacitor 5. Thus, the liquid crystal on each pixel electrode 4 is driven by the potential difference between the pixel voltage applied to the pixel electrode 4 and the counter voltage applied to the counter electrode 14.

During one frame period in which the entire display screen is scanned once, that is, until the next gate voltage is applied, the pixel voltage at that time is held by the storage capacitor 5, and the liquid crystal is driven. Note that one frame period means that one display screen is vertically scanned once from top to bottom in the liquid crystal panel.

In this way, scanning is sequentially performed from the scanning line G1, and at this time, a signal voltage suitable for the driving state of each pixel is applied to all the signal lines 11 (supplying a display signal).
By doing so, all the necessary pixels can be displayed.

The correction signal transmitted through the correction signal line 13 can be supplied to the pixel electrode 4 via the TFT 2.

The correction signal and the operation of the pixel of the liquid crystal display device will be described below.

First, the correction signal will be described. The correction signal is based on the potential between the source and drain (both ends) of the TFT 2 based on the potential of the pixel electrode 4, and is, for example, in a constant cycle (for example, every horizontal line), plus (+) polarity or minus (-). The signal has a polarity (+ inversion drive or −inversion drive).

The inversion cycle control of the correction signal is specifically performed by using the correction signal generation circuit 15 shown in FIG.

That is, the inversion cycle control of the correction signal is 1H
This is performed by using a clock signal supplied from a general gate driver (gate driver 22) that generates a scanning signal (ON signal) of a driving transistor for each (horizontal line) and used for ON / OFF timing control in the TFT 1. The correction signal generation circuit 15 controls the inversion (polarity inversion) of the correction signal to the opposite polarity and sets the voltage value.

As described above, the correction signal generating circuit 15 is operated for a predetermined period based on the clock signal for timing the scanning, which is supplied to the TFT 1 from the gate driver 22 for line-sequentially selecting and scanning the pixels. By controlling the inversion cycle of the correction signal in which the polarity of the voltage is inverted every time, the inversion cycle can be made the same as the display signal without newly providing a circuit or the like for measuring the scanning timing. .

The positive and negative voltages of the correction signal are the same as the pixel electrode 4
A voltage range that is somewhat wider than the applied voltage range (white display signal voltage (white display voltage) or black display signal voltage (black display voltage)) may be supplied from the outside.

The above-mentioned somewhat wide voltage range is
For example, according to the light leakage characteristic shown in FIG. 6, if the source-drain voltage of the TFT 1, that is, the absolute value of the voltage applied to the pixel electrode 4 is 0.4 V or more, the light leakage current becomes saturated.

Next, the operation of one pixel region of the present liquid crystal display device will be described with reference to the timing chart of FIG. For the members such as the TFTs 1 and 2 in the following description, refer to the equivalent circuit diagram of the present liquid crystal display device shown in FIG.

Now, each signal shown in FIG. 2 will be described.

The display signal Vdata is an inverted signal transmitted through the signal line 11. That is, based on the display data, 1
As the voltage changes every H (horizontal line) period,
The polarity is reversed (vibrates).

The scanning signal Vg is a 1-pulse signal that turns on the TFT 1 once for each 1F (frame) period, and is transmitted through the scanning line 12.

Vlc1 is the storage capacitance 5 and the liquid crystal layer 6 connected to the pixel electrode 4 in the present liquid crystal display device.
Indicates the voltage of.

The correction signal Vdb is a signal whose polarity is inverted at regular intervals (for example, every 1H here) and which has a polarity opposite to Vdata (a signal vibrating in the opposite direction to the display signal Vdata). It is transmitted on line 13. That is, the correction signal Vdb has the same cycle as the display signal Vdata and is a signal having a phase opposite to that of the display signal Vdata.

The correction signal Vdb is supplied to the pixel Y after the display signal Vdata is supplied to the pixel Y, for example.
When the display signal Vdata is supplied to the pixel X,
To be supplied to.

Note that, in FIG. 2, in order to make the relationship between the correction signal Vdb and the display signal Vdata easy to understand, the above-mentioned display signal Vdata is displayed in a dotted line so as to be superimposed on the correction signal Vdb. However, where the solid line of the correction signal Vdb and the dotted line of the display signal Vdata overlap and are difficult to see, the phase of the display signal Vdata indicated by the dotted line is shifted.

As shown in FIG. 2, first, the ON voltage of the scanning signal Vg (the scanning signal for turning on the scanning line 12) is T.
A display signal Vdata that changes every 1H at the timing (Vg timing) applied to the gate electrode of FT1
Are supplied to the pixel electrode 4 via the TFT 1. As a result, the display signal Vdata is stored in the storage capacitor 5 and the liquid crystal layer 6 sandwiched between the pixel electrode 4 and the counter electrode 14, and the display data is displayed in the pixel corresponding to the pixel electrode 4.

After that, when the off voltage of the scanning signal Vg (scanning signal for turning off the scanning line 12) is applied to the gate electrode of the TFT 1, the display signal Vdata is not supplied to the pixel electrode 4 via the TFT 1. .

The gate electrode of the TFT2 is grounded (corresponding to the off voltage of the scanning signal Vg), and the TFT2 is always in the off state.

That is, the off voltage is applied to both gate electrodes of the TFTs 1 and 2 until the display data is written (the display signal is supplied) to the pixel electrode 4 of the next frame.

After the display data has been written to the pixel electrode 4, the display signal Vdata is supplied to the source electrode of the TFT 2 while the display signal Vdata is being supplied to the signal line 11.
The correction signal Vdb whose polarity is opposite to that of ta is supplied. That is, the correction signal Vdb has a polarity opposite to that of the display signal Vdata in the 1H cycle and is inverted in polarity.

Here, the above-mentioned correction signal generation circuit 15,
As a comparative example, a liquid crystal display device that does not include the correction signal line 13 and the TFT 2 will be described with reference to FIGS. 4 and 5.

As shown in FIG. 4, in the liquid crystal display device of the comparative example, signal lines 111 and scanning lines 112 are arranged in a matrix on an active matrix substrate made of glass.

In the vicinity of the intersection of the signal line 111 and the scanning line 112, a thin film transistor (hereinafter, referred to as a switching element)
A TFT 102) is arranged. Also, this T
The pixel electrode 107 is provided on the drain electrode (D) of the FT 102.
Are connected. Further, a counter electrode 108 is formed on the counter substrate which faces the active matrix substrate with the liquid crystal layer 106 interposed therebetween.

In such a liquid crystal display device, the signal line 11
1 and the TFT 102, a display signal is applied to the liquid crystal layer 106 provided between the pixel electrode 107 and the counter electrode 108 to display an image.

Specifically, the pixel electrode 107 and the counter electrode 1
Display signal is supplied between 08 and (display signal voltage is applied)
By changing the alignment state of the liquid crystal, the liquid crystal layer 1
Display is performed by controlling the amount of light that passes through 06. The pixel electrode 107 and the counter electrode 1
The storage capacitor 105 is provided between the storage device 108 and the storage device 08.

That is, the TFT 102, the storage capacitor 105, the liquid crystal layer 106, the pixel electrode 107, the counter electrode 108, the signal line 111, and the scanning line 112 in the comparative example are respectively in the liquid crystal display device of the present embodiment shown in FIG. Storage capacitor 5, liquid crystal layer 6, pixel electrode 4, counter electrode 14, signal line 1
1 corresponds to the scanning line 12.

The operation of one pixel area in the liquid crystal display device as a comparative example is shown in the timing chart of FIG.

Here, the display signal Vdata is the signal line 1
11 is the inverted signal transmitted. That is, based on the display data, the voltage changes every 1H (horizontal line) period and the polarity is inverted (oscillated).

The scanning signal Vg is a 1-pulse signal for turning on the TFT 102 once every 1F (frame) period, and is transmitted through the scanning line 112.

Vlc2 is the storage capacity 105 / liquid crystal layer 10
The voltage of 6 is shown.

As shown in FIG. 5, first, at the timing (Vg timing) when the ON voltage of the scanning signal Vg is applied to the gate electrode of the TFT 102, the display signal Vdata which changes every 1H is transmitted through the TFT 102 to the pixel. Electrode 1
It is supplied to 07. As a result, the display signal Vdat
a is stored in the storage capacitor 105 and the liquid crystal layer 106 sandwiched by the pixel electrode 107 and the counter electrode 108, and display data is displayed in the pixel corresponding to the pixel electrode 107.

After that, the gate electrode (G) of the TFT 102
When the off voltage of the scanning signal Vg is applied to the display signal Vg
Data will not be supplied to the pixel electrode 107 via the TFT 102.

In the liquid crystal display device having such a structure, the TF
When T102 is irradiated with light, a pair of electrons and holes is generated in the depletion layer portion of the pn junction (pn diffusion junction), and a current (light leakage current) is generated between the source electrode and the drain electrode.
Will flow.

Therefore, as shown in FIG.
When the off voltage of the scanning signal Vg is applied to the gate electrode (G), the absolute value of Vlc2 decreases.

That is, a light leak current is generated between the source and the drain of the TFT 102, which causes crosstalk and deterioration of contrast. As a result, the absolute value of Vlc2 decreases even though the TFT 102 is in the off state.

On the other hand, the liquid crystal display device of this embodiment is provided with the correction signal generation circuit 15, and the correction signal generated by the correction signal generation circuit 15 is supplied to the correction signal lines 13 and T.
The voltage is applied to the pixel electrode 4 via the FT2.

Thus, it has the same period as the display signal,
In addition, a correction signal Vdb generated so as to apply a correction signal having a phase opposite to that of the display signal to the pixel electrode 4, that is, a correction signal Vdb generated so as to reverse polarity (reverse oscillation) with respect to the display signal is always the source of the TFT 2. The electrodes are supplied at a constant cycle (for example, every 1H).

As a result, a light leak current having a reverse polarity (hereinafter referred to as a reverse light leak current) with respect to the light leak current generated between the pixel electrode 4 and the signal line 11 between the source and drain of the TFT 1 is generated. Between the source and drain of TFT2,
That is, it can be generated between the pixel electrode 4 and the correction signal line 13.

That is, immediately after the light leak current between the signal line 11 and the pixel electrode 4 which is generated by supplying the display signal oscillating at a constant cycle (eg, every 1H) to the signal line 11 is generated. In response to the above, a reverse light leak current can be generated.

Therefore, as shown in FIG. 2, the voltage (display data) held in the storage capacitor 5 and the liquid crystal layer 6 connected to the pixel electrode 4 is very small around the initial write voltage as indicated by Vlc1. Since the increase / decrease is repeated, the absolute value does not decrease unlike Vlc2 shown in the comparative example.

In this way, the fluctuations of the voltage of the storage capacitor 5 and the liquid crystal layer 6 shown as Vlc1 become small on average. Therefore, it is possible to prevent the display quality from deteriorating due to the light leakage current and improve the display quality of the liquid crystal display device.

As described above, the liquid crystal display device of this embodiment displays on the source electrode of the TFT 2 while the display signal is being supplied to the signal line 11 after the writing of the display data to the pixel electrode 4 is completed. A correction signal inverted in polarity opposite to the signal is supplied.

That is, the signal line 11 for transmitting the display signal,
Pixel electrodes 4 arranged in a matrix corresponding to the pixels,
In a liquid crystal display device including a TFT 1 (transistor) in which a source electrode is connected to the signal line 11 and a drain electrode is connected to the pixel electrode 4, a light leak occurs between the signal line 11 and the pixel electrode 4 (between the source and the drain). A correction signal generation circuit 15 that supplies a correction signal for generating a reverse light leak current having a polarity opposite to that of the current to the pixel electrode 4 is provided.

The correction signal is supplied to the pixel electrode 4 via the correction signal line 13 and the TFT 2 when the display signal is not supplied to the pixel electrode 4 by the TFT 1.

Normally, when the TFT is irradiated with light, the TFT
An electron-hole pair is generated in the depletion layer portion of the pn junction (pn diffusion junction). Here, for example, assuming that the correction signal is not supplied to the pixel electrode 4, when the TFT 1 is irradiated with light, a pair of an electron and a hole is generated in the TFT 1, and a pair between the source electrode and the drain electrode in the TFT 1, that is, A light leak current is generated between the pixel electrode 4 and the signal line 11.

However, according to the above configuration, when the display signal is not supplied to the pixel electrode 4 (when the pixel signal is not written), that is, via the pixel electrode 4, the liquid crystal layer 6 and the storage capacitor 5 are provided. By supplying the correction signal to the pixel electrode 4 after the display signal is stored in the pixel electrode, a reverse light leak current having a polarity opposite to the light leak current is generated in the pixel electrode 4 (between the pixel electrode 4 and the correction signal line 13). Occurs).

Therefore, the generated light leak current and the reverse light leak current cancel each other. That is, the light leak current can be nullified. As a result, it is possible to prevent the deterioration of the display quality of the liquid crystal display device due to the light leakage current, and it is possible to improve the display quality of the liquid crystal display device.

Further, the display quality of the liquid crystal display device is not deteriorated by the light leak current with a simple structure without providing a light shielding film for blocking the incident light to the TFT (switching element) inside the liquid crystal display device. Can be prevented.

The voltage of the correction signal is larger than the voltage of the display signal when the display screen is black display or white display (the potential of the pixel electrode 4 is the black level potential or the white level potential), for example. (The amplitude of the correction signal is larger than the amplitude of the display signal).

That is, the potential of the pixel electrode 4 (pixel electrode potential)
By making the difference (potential difference) between the potential of the correction signal and the potential of the correction signal larger than the difference between the potential of the pixel electrode and the potential of the display signal, it is possible to generate a reverse light leak current that can cancel the light leak current.

The correction signal when the display screen is black or white will be described below.

Normally, when a display signal (black level display signal or white level display signal) for making the display screen black display or white display is supplied to the pixel electrode 4, the signal line 1
Since the potential difference between 1 and the pixel electrode 4 (the difference between the voltage of the display signal and the voltage applied to the pixel electrode 4) becomes large, the light leakage current also becomes a large current. In particular, the light leak current in this case is saturated (saturated current).

Therefore, as described above, rather than the amplitude of the display signal transmitted through the signal line 11, for example, the correction signal Vd
Increase the amplitude of b. At this time, even if the light leak current between the pixel electrode 4 having the black level potential or the white level potential and the signal line 11, that is, the light leak current having a saturated current value, the voltage of the correction signal and the pixel electrode 4 are used. The reverse photo-leakage current based on the difference between the applied voltage and the photo-current has a current value (saturated current value) that is approximately the same as the above-mentioned photo-leakage current, and can be offset.

That is, the voltage value of the correction signal (for example, the positive value and the negative value) is set to a value (voltage value) that can bring the reverse light leakage current generated in the TFT 2 into a saturated state (saturated current value). .

As a result, the light leak current and the reverse light leak current can be more reliably offset, and the deterioration of the display quality of the liquid crystal display device can be prevented.

Note that FIG. 6 may be referred to as an example showing the relationship between the light leakage current having the saturated current value and the voltage difference (potential difference).

Further, in general, the display change of the liquid crystal display device due to the potential change of the pixel electrode 4, that is, the voltage change of the storage capacitor 5 and the liquid crystal layer 6, often appears remarkably in the display at the halftone level due to the visual characteristics. . That is, in the display of an extreme white level or black level, it may be difficult to show the influence of display quality deterioration due to display unevenness.

Therefore, by canceling the light leak current using the above-mentioned correction signal when the display of the liquid crystal display device shows the halftone level, the display quality of the liquid crystal display device is most effectively improved. Can be achieved.

When the correction signal Vdb is supplied in such a halftone level display, the amplitude of the correction signal is smaller than the amplitude of the correction signal supplied in the above black level or white level display. I don't care.

This is because the potential of the pixel electrode 4 is the potential of the halftone level and is smaller than the potential at the black level or the white level, so that the amplitude of the correction signal is more than in the case of the display at the black level or the white level. This is because even if it is small, it is possible to sufficiently prevent the deterioration of display quality.

In this embodiment, a leak current (dark leak current) due to heat or an electric field may be generated in the TFT 1 which is a switching element.

However, dark leakage current (dark current)
Is an LDD (Lightly
By adopting the Doped Drain) structure, it is possible to reduce the influence of the potential fluctuation.

Moreover, the effect of this embodiment is that the pixel electrode 4
It can be said that the apparent average voltage of the pixel electrodes 4 becomes constant irrespective of the inversion driving of the liquid crystal by repeating a slight increase / decrease around the initial write voltage to.

Further, the black display voltage can be expressed as a Hi side voltage and the white display voltage can be expressed as a Lo side voltage.

It is preferable that the cycle of the correction signal is longer than the frame cycle.

Normally, the potential fluctuation of the pixel electrode 4, which changes due to the supply of the correction signal (light leak current and reverse light leak current), appears to the human eye as a flicker phenomenon when it reaches a certain level.

However, by setting the cycle of the correction signal to be the frame cycle (generally 1/60 seconds) or more,
It is possible to suppress the potential fluctuation of the pixel electrode due to the correction signal. Therefore, the flicker phenomenon can be prevented from being visually recognized, and the display quality of the liquid crystal display device can be improved.

[0164]

As described above, in the liquid crystal display device of the present invention, the correction signal for generating the reverse light leak current having the opposite polarity to the light leak current generated between the signal line and the pixel electrode is supplied to the pixel. This is a configuration including a correction signal supply unit that supplies the electrodes.

Thus, for example, when the display signal is not supplied to the pixel electrode (when not being written in the pixel), that is, after the display signal is stored in the liquid crystal / storage capacitor via the pixel electrode, for example. By supplying the correction signal to the pixel electrode, a reverse light leak current having a polarity opposite to that of the light leak current is generated in the pixel electrode.

Therefore, the generated light leak current and the reverse light leak current cancel each other out, and the light leak current becomes invalid. As a result, it is possible to prevent the display quality from deteriorating due to the light leak current, and it is possible to provide a liquid crystal display device having a good display quality.

Further, it is possible to prevent the deterioration of the display quality of the liquid crystal display device due to the light leakage current with a simple structure without providing a light shielding film for blocking the light incident on the switching element inside the liquid crystal display device. There is an effect that can be.

The liquid crystal display device of the present invention has a configuration in which the correction signal is a signal having the same period as the display signal and a polarity opposite to that of the display signal.

As a result, for example, when a display signal oscillating at a constant cycle (for example, every horizontal line) is supplied to the signal line, light generated between the signal line and the pixel electrode is generated at the constant cycle. A back light leakage current can be generated immediately after the generation of the leakage current.

Therefore, for example, the voltage (voltage of the liquid crystal / storage capacity) between the pixel electrode and the counter electrode facing the pixel electrode repeats a slight increase / decrease around the initial write voltage, The fluctuation can be reduced on average. As a result, the display quality of the liquid crystal display device can be prevented from being deteriorated due to the light leakage current.

The liquid crystal display device of the present invention has a configuration in which the correction signal is a signal having a period longer than the frame period and having a polarity opposite to that of the display signal.

Accordingly, by setting the period of the correction signal to be the frame period (generally 1/60 seconds) or more, the potential fluctuation of the pixel electrode due to the correction signal can be suppressed.

Therefore, it is possible to prevent the flicker phenomenon from being visually recognized and to improve the display quality of the liquid crystal display device.

In the liquid crystal display device of the present invention, the amplitude of the correction signal is larger than the amplitude of the display signal.

Accordingly, the amplitude of the correction signal is larger than that of the display signal, that is, the voltage value of the correction signal is larger than the difference between the voltage applied to the pixel electrode and the voltage of the display signal. And the voltage of the correction signal are set to be large.

Therefore, even if the light leak current has a large value, that is, the light leak current having a saturated current value, the reverse light leak current generated by the correction signal is
It becomes a current value (saturated current value) that is approximately the same as the light leakage current, and cancellation is possible.

As a result, the light leak current and the reverse light leak current can be more reliably offset, and the display quality of the liquid crystal display device can be prevented from being degraded.

In the liquid crystal display device of the present invention, the correction signal supply means is based on the clock signal for measuring the scanning timing, which is supplied to the transistor from the gate driver for line-sequentially selecting and scanning the pixels. It is configured to control the inversion cycle of the correction signal in which the polarity of the voltage is inverted every predetermined period.

Thus, by controlling the inversion cycle of the correction signal using the clock signal, the inversion cycle can be made the same as that of the display signal without newly providing a circuit for measuring the scanning timing. It has the effect of being able to.

The liquid crystal display device of the present invention is, as described above,
A reverse current generating unit that generates a reverse light leakage current having a polarity opposite to that of the light leakage current generated between the signal line and the pixel electrode and canceling the light leakage current is provided in the pixel electrode.

Thus, for example, when the display signal is not supplied to the pixel electrode, the back light leakage current is generated in the pixel electrode, and the light leakage current and the back light leakage current that are generated cancel each other out. Therefore, it is possible to prevent the display quality from deteriorating due to the light leakage current, and it is possible to provide a liquid crystal display device having good display quality.

Further, it is possible to prevent the deterioration of the display quality of the liquid crystal display device due to the light leak current with a simple structure without providing a light shielding film for blocking the light incident on the switching element inside the liquid crystal display device. There is an effect that can be.

As described above, the driving method of the liquid crystal display device of the present invention generates the correction signal for generating the reverse light leak current having the opposite polarity to the light leak current generated between the signal line and the pixel electrode. However, when the display signal is not supplied to the pixel electrode by the transistor, the correction signal is supplied to the pixel electrode.

As a result, when the display signal is not supplied to the pixel electrode (when the pixel is not writing),
That is, after the display signal is stored in the liquid crystal / storage capacitor through the pixel electrode, the correction signal is supplied to the pixel electrode, so that the reverse light leak current having the opposite polarity to the light leak current is generated.
It occurs in the pixel electrode.

Therefore, the generated light leak current and the reverse light leak current cancel each other out, and the light leak current becomes invalid. As a result, it is possible to prevent the display quality from deteriorating due to the light leak current.

Further, it is possible to prevent the deterioration of the display quality due to the light leakage current with a simple structure without providing a light-shielding film for blocking the light incident on the switching element inside the liquid crystal display device. Play.

The driving method of the liquid crystal display device of the present invention is such that the correction signal is a signal having the same period as the display signal and a polarity opposite to that of the display signal.

As a result, for example, when a display signal that oscillates at a constant cycle (for example, every horizontal line) is supplied to the signal line, light generated between the signal line and the pixel electrode is generated at the constant cycle. A back light leakage current can be generated immediately after the generation of the leakage current.

Therefore, for example, the voltage between the pixel electrode and the counter electrode facing the pixel electrode repeats a slight increase / decrease around the initial write voltage, and the voltage fluctuation can be reduced on average. As a result, it is possible to further prevent the display quality of the liquid crystal display device from being deteriorated due to the light leakage current.

The driving method of the liquid crystal display device according to the present invention is such that the correction signal is a signal having a period equal to or longer than the frame period and a polarity opposite to that of the display signal.

Thus, by setting the period of the correction signal to be equal to or longer than the frame period, it is possible to suppress the potential fluctuation of the pixel electrode due to the correction signal. Therefore, it is possible to prevent the flicker phenomenon from being visually recognized, and it is possible to improve the display quality of the liquid crystal display device, for example.

The driving method of the liquid crystal display device of the present invention is configured such that the amplitude of the correction signal is set to be larger than the amplitude of the display signal.

As a result, the amplitude of the correction signal becomes larger than that of the display signal, that is, the voltage value of the correction signal is applied to the pixel electrode more than the difference between the voltage applied to the pixel electrode and the voltage of the display signal. The difference between the voltage and the voltage of the correction signal is set to be large.

Therefore, even if the light leak current has a large value, that is, the light leak current has a saturated current value, the reverse light leak current generated by the correction signal is
It becomes a current value (saturated current value) that is approximately the same as the light leakage current, and cancellation is possible. That is, the light leak current can be invalidated.

As a result, it is possible to more reliably cancel the light leak current and the reverse light leak current, and it is possible to provide a liquid crystal display device having a good display quality, for example.

The driving method of the liquid crystal display device of the present invention is such that the correction signal is supplied to the pixel electrode when the display of the liquid crystal display device shows a halftone level.

As a result, the cancellation of the light leak current using the correction signal is performed when the display of the liquid crystal display device represents the halftone level, so that the display quality of the liquid crystal display device is most effectively improved. The effect that it can be achieved is produced.

When a correction signal is supplied in such a halftone level display, the amplitude of the correction signal is
The amplitude may be smaller than the amplitude of the correction signal supplied in displaying the black level or the white level.

[Brief description of drawings]

FIG. 1 is an equivalent circuit diagram showing a configuration of a main part of a liquid crystal display device according to an embodiment of the present invention.

FIG. 2 is a timing chart of each signal in the equivalent circuit shown in FIG.

FIG. 3 is a circuit diagram showing a configuration of a correction signal generation circuit.

FIG. 4 is an equivalent circuit diagram showing a configuration of a main part of a liquid crystal display device of a comparative example.

5 is a timing chart of each signal in the equivalent circuit shown in FIG.

FIG. 6 is a graph showing a relationship between a light leak current and a source-drain voltage of a TFT.

FIG. 7 is a cross-sectional view showing a configuration of a main part of a conventional liquid crystal display device.

FIG. 8 is a graph showing a relationship between a liquid crystal applied voltage and a display unevenness level in another conventional liquid crystal display device.

[Explanation of symbols]

1 TFT (transistor) 2 TFT 4 pixel electrode 5 liquid crystal layer 6 storage capacity 11 signal line 12 scanning line 13 correction signal line 14 counter electrode 15 correction signal generation circuit (correction signal supply means, reverse current generation means) 21 source driver 22 gate Driver Vdata Display signal Vg Scan signal Vdb Correction signal Vlc1 Storage capacity / voltage of liquid crystal layer

─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁷ Identification code FI theme code (reference) G09G 3/20 624 G09G 3/20 624B 641 641C F term (reference) 2H093 NA43 NA79 NC01 NC62 NC67 NC90 ND36 5C006 AA16 AC11 AC25 AC27 AC28 AF44 AF46 AF51 AF53 BB16 BC06 BC20 FA18 FA36 5C080 AA10 BB05 DD10 EE28 FF11 JJ02 JJ04 JJ05 JJ06

Claims (11)

[Claims] 1. A signal line for transmitting a display signal, pixel electrodes arranged in a matrix corresponding to pixels, a transistor having a source electrode connected to the signal line and a drain electrode connected to the pixel electrode. The liquid crystal display device includes a correction signal supply unit that supplies a correction signal for generating a reverse light leak current having a polarity opposite to that of the light leak current generated between the signal line and the pixel electrode, to the pixel electrode. A liquid crystal display device characterized by the above. 2. The liquid crystal display device according to claim 1, wherein the correction signal is a signal having the same period as that of the display signal and a polarity opposite to that of the display signal. 3. The liquid crystal display device according to claim 1, wherein the correction signal is a signal having a period of a frame period or more and a polarity opposite to that of the display signal. 4. The liquid crystal display device according to claim 1, wherein the amplitude of the correction signal is larger than the amplitude of the display signal. 5. A gate driver for line-sequentially selecting and scanning the pixels is supplied to the transistors.
Based on the clock signal for timing the scan,
3. The liquid crystal display device according to claim 1, wherein the correction signal supply unit controls the inversion cycle of the correction signal in which the polarity of the voltage is inverted every predetermined period. 6. A signal line for transmitting a display signal, a pixel electrode arranged in a matrix corresponding to a pixel, a transistor having a source electrode connected to the signal line and a drain electrode connected to the pixel electrode. In the liquid crystal display device, a reverse current generation unit that generates a reverse light leakage current having a polarity opposite to that of the light leakage current generated between the signal line and the pixel electrode in the pixel electrode, which cancels the light leakage current. A liquid crystal display device comprising: 7. A transistor having a scanning line connected to a gate electrode, a pixel electrode connected to a drain electrode and a signal line connected to a source electrode is turned on by a scanning signal transmitted by the scanning line. In the method of driving a liquid crystal display device for supplying the display signal transmitted by the signal line to the pixel electrode, a reverse light leak current having a polarity opposite to that of the light leak current generated between the signal line and the pixel electrode is generated. A method for driving a liquid crystal display device, comprising generating a correction signal for generating the pixel signal, and supplying the correction signal to the pixel electrode when the display signal is not being supplied to the pixel electrode by the transistor. 8. The method of driving a liquid crystal display device according to claim 7, wherein the correction signal is a signal having the same period as the display signal and a polarity opposite to that of the display signal. 9. The method of driving a liquid crystal display device according to claim 7, wherein the correction signal is a signal having a period equal to or longer than a frame period and having a polarity opposite to that of the display signal. 10. The method of driving a liquid crystal display device according to claim 7, wherein the amplitude of the correction signal is set to be larger than the amplitude of the display signal. 11. The liquid crystal display device according to claim 7, wherein the correction signal is supplied to the pixel electrode when the display of the liquid crystal display device indicates a halftone level. Driving method for liquid crystal display device.