JPH03181988A - Driving method for liquid crystal display element - Google Patents

Abstract

PURPOSE:To improve view angle characteristics by making color filters of the same color correspond to plural adjacent picture elements and applying signal voltages which differ in signal amplitude. CONSTITUTION:Two picture elements 21 and 22 which adjoin along a scanning line 15 are combined as picture elements of the same color opposite a color filter 12 of the same color. A signal line 16 connected to one picture element 21 and a signal line 16 connected to the other picture element 22 are different and supplied with mutually independent potential signals. Then both the picture elements 21 and 22 are applied with signal voltages which differ in signal amplitude through the signal lines 16. Therefore, the transmissivity-signal potential characteristic is obtained by averaging the characteristics of those picture elements 21 and 22 and the visible inversion of light and shade of a display image plane is hardly caused. Consequently, the view angle characteristics are improved.

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention] (Industrial Application Field) The present invention relates to a method for driving a liquid crystal display element used in televisions, graphic displays, etc.

(Prior Art) In recent years, graphic displays for televisions or OA equipment that are constructed using active matrix liquid crystal display elements have been widely used.

As a switch element of the liquid crystal display element, T
PT, MIM, etc. are used, but Fig. 4 shows TPT.
1 is a cross-sectional view of one pixel portion of an active matrix liquid crystal display element equipped with the following.

In FIG. 4, 1 is made of transparent glass, for example.
A gate electrode 2 is formed on the entire surface of the first substrate 1, and a gate insulating film 3 made of, for example, SiOx is formed on the gate electrode 2. A semiconductor layer 4 made of, for example, amorphous silicon (a-8i) is formed on the gate insulating film 3 at a portion facing the gate electrode 2, and a drain electrode 5 and a source electrode 6 are formed on the semiconductor layer 4. is formed. This drain electrode 5
The source electrode 6 and the source electrode 6 are obtained by, for example, sequentially coating a Mo film and a ^l film using the vine method, and then machining and etching them into a predetermined shape. In this way, a thin film transistor (Thin Fi) is formed as a predetermined thin film element on the entire surface of the first substrate 1.
le Ttsnsislor, TFT) 7 is formed.

Further, on the gate insulating film 3 and adjacent to the source region side of the semiconductor layer 4, for example, ITO (Indi■Tin 0
After coating the pixel electrode 8 with a pixel electrode 8, a pixel electrode 8 is provided by photo-etching into a predetermined shape, and the source electrode 6 extends and is connected to one end of the pixel electrode 8. Furthermore, a protective layer 9 made of, for example, SiOx is formed on the entire surface of the first substrate 1.

Reference numeral 10 denotes a second substrate made of, for example, transparent glass, and a light shielding layer 1 as a black matrix having predetermined openings corresponding to the pixel electrodes 8 on the entire surface of the second substrate 10.
] is formed, a color filter 12 is provided in the opening of the light shielding layer 11, and a counter electrode ]3 made of, for example, ITO is formed over the entire surface of the light shielding layer 11 and the color filter 12.

Then, the first substrate 1 and the second substrate 10 are combined so that their whole surfaces face each other, and the first substrate 1 and the second substrate 10 are
A liquid crystal layer 14 is sandwiched between the substrate 10 and the liquid crystal layer 14 .

In this way, the TFT 7 on the substrate 1 and this TF
One pixel is constituted by the pixel electrode 8 connected to T7 and the counter electrode 13 on the second substrate 10.

As shown in FIG. 5, these pixels are arranged in a matrix in rows and columns, and the gate electrodes 2 of each pixel are integrally connected between each pixel on the first substrate 1. A plurality of signal lines 16 are arranged in which the scanning line 15 and the drain electrode 5 of each pixel are integrally connected, and as shown in FIG. A color filter 12 is arranged, the color of which consists of the normal field R1 edge G and blue B.

In each of the pixels, adjacent pixels have different colors and are arranged regularly, and independent potential signals are applied to these pixels from each signal line 16 using a gate pulse from the scanning line 15 as a switch, Alternatively, if multiple pixels of the same color are placed adjacent to each other, each of these pixels is given an independent T.
Even though FT7 is provided, there are cases where the same signal is given.

The first substrate 1 as an active matrix array in FIG. 5 and the second substrate 10 as a color filter body in FIG. After the films are formed, they are rubbed in the directions shown by the arrows and assembled so that their respective corners C coincide with each other. In the liquid crystal display element created in this way, the display screen When observed from the outer surface (other principal surface side) of the second substrate 10, the viewing angle direction is upward toward the liquid crystal display element.

(Problems to be Solved by the Invention) In the above-mentioned liquid crystal display element, as shown in FIG.
The transmittance of the liquid crystal depends on the signal potential, and in television displays, etc., all of these parts are used to express shading. However, this transmittance-signal potential characteristic changes depending on the direction in which the liquid crystal display element is observed. Particularly in the viewing angle direction, as shown in the same figure, the curve once reaches a minimum and maximum in the middle, and the transmittance does not decrease monotonically with respect to the signal potential amplitude. For this reason, a phenomenon occurs in which the visible shading is opposite to the actual one, and the displayed image becomes unnatural.

The present invention aims to solve such problems,
The purpose is to improve the viewing angle characteristics of a liquid crystal display element.

[Structure of the invention]

(Means for Solving the Problem) The present invention combines first and second substrates each having an electrode formed on one main surface so that the one main surface side faces each other, and
and a liquid crystal layer sandwiched between the second substrates, and
In a method for driving a liquid crystal display element, in which pixels are configured in a matrix, and each pixel corresponds to a color filter formed on at least one of the first and second substrates, a plurality of adjacent pixels The color filters of the same color correspond to the color filters, and signal voltages having different signal amplitudes are applied.

(Function) In the present invention, by applying independent and different potential signals to adjacent pixels of the same color, the transmittance of these adjacent pixels of the same color is changed, and at the same time, the dependence of the transmittance on the observation angle is reduced, and the visible This alleviates the inversion of shading on the display screen.

(Example) An embodiment of the present invention will be described below with reference to FIG.

The liquid crystal display element shown in FIG. 1 basically has the same structure as shown in FIGS. 4, 5, and 6, and therefore the details of the liquid crystal display element itself are Further explanation will be omitted.

That is, as shown in FIG.
, a TFT 7 consisting of a drain electrode 5 and a source electrode 6, and a pixel electrode 8 connected to the source electrode 6 of this TFT 7.
A protective layer 9 is formed to cover these TFTs 7 and pixel electrodes 8, and an active matrix array is formed as a whole. Further, a light shielding layer 11, a color filter 12, and a counter electrode I3 are formed on the whole surface of the second substrate 10, and the first substrate 1 and the second substrate 10 are arranged so that their whole surfaces face each other. The liquid crystal layer 14 is sandwiched between the first substrate 1 and the second substrate 10, and the TFT 7 on the first substrate 1, the pixel electrode 8 connected to this TFT 7, and the second substrate 10 are combined as shown in FIG. The upper counter electrode 13 constitutes one pixel.

As shown in FIG. 1, these pixels are arranged in a matrix in rows and columns, and the gate electrodes 2 of each pixel are integrally connected between each pixel on the first substrate 1. A plurality of signal lines 16 are arranged in which the scanning line 15 and the drain electrode 5 of each pixel are integrally connected, and a red R is arranged at a position facing each pixel on the second substrate 10.
A color filter 12 consisting of green G and blue B is arranged, and the display screen is changed to a second color by the rubbing process as described above.
When observed from the outer surface (other principal surface side) of the substrate 10, the viewing angle direction is upward toward the liquid crystal display element.

In such a liquid crystal display element, the signal potential of the signal line 16 is written into the source electrode 6 and the pixel electrode 8 by a gate pulse applied to the scanning line 15, and then a gate pulse is applied to the same scanning line 15. This signal potential is held by the capacitance of the liquid crystal layer I4 until it is applied.

Note that the potential signal is usually an alternating current signal in order to prevent deterioration of the liquid crystal.

In the liquid crystal display element as described above, R and G in FIG.
, B mean red, green, and blue color filters 12, respectively, and in FIG. color filter 2 so as to face each other. Also, the signal line 1 connected to this one pixel 21
6 is different from the signal line 16 connected to the other pixel 22, so that independent potential signals are supplied to each pixel.

Then, signal voltages having different signal amplitudes are applied to both pixels 2 and 22 through different signal lines 16. That is, for example, if the amplitude of the potential signal supplied to the other pixel 22 is always set to 475 of the amplitude of the potential signal supplied to the one pixel 21, the amplitude of the potential signal supplied to the other pixel 22
Pixel 2 from above when the horizontal axis is the signal potential amplitude of 1.
The transmittance-signal potential characteristics when observing I and the pixel 22 are curves as shown in FIG. 2, respectively. Therefore, the transmittance-signal potential characteristic when observing the entire display screen is the average of the respective characteristics of these pixels 21 and 22, and this characteristic is the transmittance-signal potential characteristic of only one pixel 21. Since the peak in the halftone region is smaller than that in the half-tone area, it is less likely that the visible gradation of the display screen will be reversed.

In this way, by connecting adjacent pixels 21 and 22 of the same color to different signal lines 16 and applying independent and different potential signals, the transmittance of these adjacent pixels 21 and 22 of the same color can be changed, and at the same time, the transmittance can be changed. It is possible to reduce the viewing angle dependence of the ratio and to alleviate the visible inversion of shading on the display screen.

In the above embodiment, a case has been described in which the two pixels 21 and 22 connected to two different signal lines 16 are pixels of the same color. This method can also be applied to the case where the pixels are of the same color. That is, as shown in FIG. 3, two pixels 2 adjacent to each other along the signal line 16
3.24 are pixels of the same color, and the scanning line 15 is connected to one pixel 23 and the other pixel 24,
The scan line 15 is different from the scan line 15, and both scan lines 15
Assume that no gate pulse is applied to . In this way, signal voltages having different signal amplitudes are applied to these two pixels 23 and 24.

For example, if the potential signal given to the other pixel 24 is set to 475 of the potential signal given to the one pixel 23, the same effect as in the above embodiment can be obtained.

In this way, by connecting adjacent pixels 23 and 24 of the same color to different scanning lines 15 and applying different potential signals from the same signal line 16 by changing the switch timing, the adjacent pixels 23 and 24 of the same color At the same time, it is possible to change the transmittance of the pixels 23 and 24, reduce the viewing angle dependence of the transmittance, and alleviate the visible inversion of shading on the display screen.

In the above description, the present invention is applied to an active matrix type liquid crystal display element, but the present invention is not limited to this, and may be applied to a simple matrix type liquid crystal display element.

Further, in implementation, the color filter may be provided on the first substrate side, and three or more adjacent pixels of the same color may be arranged in parallel.

〔Effect of the invention〕

As described above, according to the present invention, by applying different signal voltages to a plurality of adjacent pixels of the same color, the phenomenon of reversal of visible shading in the viewing angle direction is alleviated, and the viewing angle dependence of the liquid crystal display is reduced. By doing so, the viewing angle characteristics of the liquid crystal display element can be substantially improved.

[Brief explanation of drawings]

FIG. 1 is a plan view of a liquid crystal display device according to an embodiment of the present invention, FIG. 2 is a transmittance-signal potential characteristic diagram of the liquid crystal display device of the present invention, and FIG. 3 is a diagram showing another embodiment of the present invention. 4 is a cross-sectional view of a conventional liquid crystal display element, FIGS. 5 and 6 are partial plan views of the liquid crystal display element shown in FIG. 4, and FIG. 7 is a conventional one. FIG. 3 is a transmittance-signal potential characteristic diagram in a liquid crystal display element of FIG. 1..First substrate, 8..Pixel electrode, lO..Second substrate,
12...Color filter, 13...Counter electrode, 14...Liquid crystal layer, 21.22.23.24...Pixel.

Claims (1)

[Claims] (1) First and second substrates having electrodes formed on one main surface are combined so that the one main surface side faces each other, and a liquid crystal layer is sandwiched between the first and second substrates. , and a method for driving a liquid crystal display element, in which pixels are arranged in a matrix, and each pixel corresponds to a color filter formed on at least one of the first and second substrates, A method for driving a liquid crystal display element, characterized in that the color filters of the same color correspond to the pixels, and signal voltages having different signal amplitudes are applied to the pixels.