JPH0363623A - Driving method for liquid crystal display device - Google Patents

Abstract

PURPOSE:To make a display of high-definition even when the density is made high by dividing a counter electrode corresponding to respective pixels and setting the potentials of the divided counter electrodes to different values corresponding to the charge potentials of the respective pixels. CONSTITUTION:Counter electrodes on the common side of a TFT liquid crystal display device, e.g. odd-numbered electrodes COM11, COM13 -COM12n-1 in a 1st column are led out from above and even-numbered electrodes COM12, COM14 - COM12n are led out from below. Then the odd-numbered electrode lines La1, La2 - La2m which are led out from above are applied with common potentials which decrease in order and the even-numbered electrode lines Lb2m, Lb2m-1 - Lb1 are applied with common potentials which increase in order, so that the respective pixels are driven with the constant contrast.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a method for driving a liquid crystal display device that corrects distortion of charge potential in each pixel.

[Conventional technology]

A conventional liquid crystal display device has an equivalent circuit configuration as shown in FIG. That is, as shown in the figure, a plurality of gate lines Gl, G2 . ...02m and drain lines Di, D2. ..., D2. are arranged in a matrix, and one transistor 11 is provided at each intersection.

The gate lines Gl, G2°..., G2. , the odd-numbered lines Gl, . . . , c2fi-1 are led out from the left side, and the even-numbered lines G2 . ..., G2.
is derived to the outside from the right side. In addition, drain lines Di, D2. ..., D2. is the odd numbered line Dl
,..., D2m-1 are led out from above to the outside, and even-numbered lines D2. ... D2. is led out from the bottom.

The transistor 11 has gate electrodes corresponding to gate lines Gl, 02 . ..., G2. , and the drain electrodes are connected to corresponding drain lines Dl, D2 . ..., D2. The source electrode is connected to the pixel (liquid crystal display element) C1, 1°C21,...
C2m1+...C1,2□ C2,2□...
- Connected to the signal electrode of C2m + 2m. The counter electrodes of these pixels Cl-1r C2-1+ are connected to the common line 14. Each pixel C above
11°C21, . . . is equivalently shown as a liquid crystal capacitor 12 and a liquid crystal resistor 13 connected in parallel.

However, conventional liquid crystal display devices have a structure in which a liquid crystal layer is sandwiched between the panel configured as described above and a counter electrode with an ITO film (transparent conductive film) deposited on the negative side. The liquid crystal is driven by the potential difference between the potential charged in the pixel C and the counter electrode potential.

[Problems to be Solved by the Invention] In the above-mentioned liquid crystal display device, when increasing the density of pixels, the gate line becomes finer and the number of intersections between the gate line and the drain line and the transistor increases. This causes an increase in the resistance and capacitance of the transistor, which causes propagation distortion of the gate pulse that drives the transistor. For example, all pixels C on the gate line Gl
1, l+..., C2s, l, when trying to charge a signal of the same potential vO to the pixels C1, C2s, l, the propagation distortion of the gate pulse causes distortion in the charging potential as shown in FIG. 4(a). A difference of ΔV occurs between the potentials charged to l, C2@, and I. Similarly, the potential charged to the pixel on the gate line G2 is shown in FIG. 4(b).
Distortion occurs in the charge potential as shown in .

The above propagation distortion is caused by the pixels C1, 1C2m +
2 + . . . , even if the signal voltage is sufficiently charged, the terminal side pixel C2s1+ CI, 2 + . . .
etc., a phenomenon such as insufficient charging occurs, and in the general wiring method in which terminals are drawn out alternately on the right and left sides of the screen, a contrast difference occurs between every other terminal, degrading the display quality.

The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a method for driving a liquid crystal display device that can obtain higher display quality even when the density of pixels is increased.

[Means for Solving the Problems] The present invention provides an active matrix drive liquid crystal display device in which a counter electrode is divided in correspondence with each pixel, and the potential of these divided counter electrodes is set to a charge potential of each pixel. This is a method of driving a liquid crystal display device characterized by setting different values in correspondence with each other.

[Operation] By dividing the counter electrode to correspond to each pixel and changing the potential of each counter electrode according to the charge potential of the corresponding pixel, the charge potential of each pixel can be changed by the propagation distortion of the gate pulse. Even if the end side and the terminal end side are different, the potential difference between the charge potential of each pixel and the counter electrode potential can be made the same, and each pixel can be driven to display with a constant contrast.

[Example] Hereinafter, one embodiment of the present invention will be described with reference to the drawings.

FIG. 1 shows the configuration and voltage supply method of the common-side counter electrode of the TPT liquid crystal display device according to the present invention. As shown in FIG.
r C21+ ・・・C2m+1+ ”' CL2
Divide to correspond to a+ C2, 2111”°1 C2m, 21+, COMI, +, C0M2.I,
...COM 2-, 1. ..., COMI, 2-, C
0M2.2□...COM 2-, 2-. The counter electrodes are divided into odd-numbered and even-numbered electrodes for each row, and the odd-numbered counter electrodes are led out from the upper side, and the even-numbered counter electrodes are led out from the lower side. For example, in the first row of counter electrodes, odd numbered electrodes C0M1. l
,COMI,3,...,C0M1.2-1 is led out from the upper side, and even numbered electrodes COM+, 2°C0
M1.4. ...,COM,,2. is led out from the bottom.

Then, the odd numbered electrode line Lal r derived from the upper side
L a2 + "' r L 82m is given common potentials Vl, V2...V2II+ whose potentials decrease sequentially as shown in ■ in FIG. 2(a), and the even number electrode line Lb2 derived from the bottom □ L b 2m-1+ ・・
, Lb, there are common potentials V2+a, . . . , V2. Give Vl. That is, the gate lines Gl, G2 . ... so that different potentials are supplied to the power supply end and the termination end. in this case,
The potential difference between the common potential Vl and V2Ia is made to match the maximum potential difference ΔV between pixels. Note that it is conventional to drive the liquid crystal by inverting the polarity of the voltage applied to the liquid crystal at certain intervals so as not to adversely affect the life of the liquid crystal. In FIG. 2(a) above, ■ indicates the charging potential of each pixel on the odd gate line, ■ indicates the conventional counter electrode potential, and ■ indicates the potential of each counter electrode on the odd gate line in the present invention. . In addition, in FIG. 2(b), ■ is the charge potential of each pixel on the even gate line,
2 shows the conventional counter electrode potential, and 2 indicates each counter electrode potential on the even-numbered gate lines in the present invention.

By dividing the counter electrode so as to correspond to each pixel as described above and setting the potential of the counter electrode to a different value for each pixel, it becomes possible to correct the distortion of the charge potential of each pixel. That is, the odd gate lines Gl,
..., C2,-, the upper pixel, for example, the pixel C1,1* on the gate line Gl in FIG. 3, C21+ ...,
The charge potential of C2m, , is higher on the feeding end side due to the propagation distortion of the gate pulse, and gradually becomes lower as it approaches the terminating end side, as shown in (■) in FIG. 2(a). On the other hand, counter electrodes COM+, +, C0M2.1, . . . provided corresponding to the pixels C8C2, I+ . . . +C2m, l
, C0M2. , , as shown in Figure 2, the above ■
A common potential V whose potential decreases sequentially in response to potential changes in
l, V2°...V2m are given. Therefore, due to the propagation distortion of the gate pulse, the pixel CI=I + C2,1
+ ... + Even if the charge potential of C2m1 is different between the power supply end side and the power termination end side, the potential difference between each counter electrode potential is the same, and each pixel is driven to display with a constant contrast.

On the other hand, even gate line G2. . . . In the G21 pixel, the potential difference between the charge potential of each pixel and the counter electrode potential is the same as in the case of the pixels on the odd gate line described above, and each pixel is displayed with a constant contrast. Driven.

Although the above embodiments have been described using thin film transistors, the present invention is not limited to thin film transistors, and can also be implemented using MOS type FETs.

[Effects of the Invention] As described in detail above, according to the present invention, in an active matrix driven liquid crystal display device, the counter electrode is divided corresponding to each pixel, and the potential of the divided counter electrode is applied to each pixel. Since the values are set to different values depending on the charge potential of the
By correcting the distortion in the charge potential of each pixel caused by the propagation distortion of the gate pulse, the contrast of each pixel can be made constant, and the pixel quality can be significantly improved.

[Brief explanation of drawings]

1 and 2 show an embodiment of the present invention, in which FIG. 1 is a configuration diagram of a counter electrode part in a TPT liquid crystal display device, FIG. 2 is a diagram showing a correction potential supply method, and FIG. 3 is a diagram showing a correction potential supply method. Figure 4 (a) and (b) are equivalent circuit diagrams of a general liquid crystal display device.
4 is a diagram showing a state in which distortion occurs in the charge potential in each pixel of FIG. 3. FIG. 11...Transistor, 12...Liquid crystal capacitor, 13.
...Liquid crystal resistance, 14...Common line, Gl, G2.
...Gate line, DI, D2. ...
drain line, CI=I r C2, I + .
. . . Pixel, COM, . . . ~ COM2-1. C.O.
M1.2-~C0M2. ,2. ...Counter electrode, La
+~La2m odd number electrode line, Lb2a~Lb,...
Even number electrode line.

Claims (1)

[Claims] In an active matrix drive liquid crystal display device in which a plurality of pixels and counter electrodes facing these pixels are arranged in a matrix, the counter electrode is divided in correspondence with each pixel, and each divided For the counter electrode,
1. A method for driving a liquid crystal display device, characterized in that different potentials are supplied to correct distortion of charge potential in each corresponding pixel.