JPH049919A - Method for driving opto-electrical device - Google Patents

Abstract

PURPOSE:To average the variation of picture electrode potential in a non- selection period by diving a selection period into two periods, i.e. a data charging period and an average period, and controlling scanning signals and data signals. CONSTITUTION:Many driving electrodes 31a, 31b are successively selected in each pair from the high position, and during the selection period, data are charged by counter electrodes 32. In this case, the selection period is divided into two periods, i.e. the data charging period in the former half (latter half) period and the data averaging period in the latter half (former half) period, to control scanning signals and data signals. Consequently, the variation of the picture element electrode potential in the non-selection period is averaged, data inputted to one picture can be stored without being influenced by data inputted to another picture element and the restriction of the capacity ratio of a picture element part to an element part can be eased.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a method for driving an electro-optical device having a pixel electrode and a nonlinear resistance element for each pixel arranged along a driving if pole.

[Summary of the invention]

The present invention provides an electro-optical device in which each pixel electrode and a plurality of nonlinear resistance elements provided for each pixel electrode are connected to two adjacent driving electrodes with each pixel electrode sandwiched therebetween. In this method, the selection period is divided into a first half and a second half, and one period is used as a data charging period, and the other period is used as a data averaging period to generate a scanning signal. By controlling the data signal and averaging the fluctuations in the pixel electrode potential during the non-selection period, it is possible to maintain the data input to one pixel without being affected by the data input to other pixels. In addition, the present invention provides a method for driving an electro-optical device in which restrictions on the capacitance ratio between a pixel portion and an element portion are relaxed.

[Conventional technology]

As a thin, lightweight, low power consumption display panel,
Liquid crystal display panels have excellent features and are currently widely used in laptops and book-type personal computers. Among these, display panels based on the actif matrix system are attracting attention as a method that can increase the amount of displayed information and improve image quality. Active elements include three-terminal elements using thin film transistors, MI
There are two-terminal elements such as nonlinear resistance elements such as M, and PN junction thin film diodes.

Among these, the three-terminal element has the disadvantage that the process is complicated due to the large number of formed films, the yield is low, and the cost is high.

Additionally, diodes have problems such as low breakdown voltage and vulnerability to static electricity. On the other hand, nonlinear resistance elements have a simple structure and can have a high breakdown voltage, so they are low cost and advantageous for application to large-area display panels.

Figure 3 fat is an X-Y matrix panel circuit diagram with an electro-optical device using a nonlinear resistance element, and Figure 3 ('
b) is a partial sectional view showing the structure of the device.

The row electrodes (driving electrodes) 31 and the column electrodes (counter electrodes) 32 are usually 100 to 1000 on the substrate B and the counter substrate A, respectively.
It is formed during this process. At the x-y intersection, there is a pixel electrode 36 and a plurality of nonlinear resistance elements 34a, 34b for each pixel electrode 36.
and two different driving electric currents Fi31a,
31b. An electro-optic material 33 is held between the substrates AB.

This type of display panel is driven as follows.

That is, a large number of drive electrodes 31a and 31b shown in FIG. 3 are selected one pair at a time from the top in line order, and data is charged by the counter electrode 32 within the selection period. FIG. 2 shows a driving waveform of a conventional electro-optical device. Figure 2) shows a scanning signal applied to a pair of row electrodes (driving electrodes) adjacent to the pixel electrode in the n+1st row; ), Figure 2 (di is the data signal applied to the column electrode (counter electrode) when all pixels in one column are turned on, Figure 2 te+ is the n-th pixel in one column) FIG. 4 is a diagram showing a data signal applied to a column electrode (counter electrode) when the pixel is ON and all remaining pixels are OFF.

2 fa) to icl show how the driving electrodes 31 are selected line-sequentially pair by pair. The potential of one of the pair of driving electrodes 31a is ■ during the display selection period. ■ during the selected period. +
Stand up to Vo. The other driving electrode 31b is at V during the non-selection period. ■ in 1 selection period. The potential is -7 inches. Therefore, both ends of the pair of nonlinear resistance elements 34a and 34b (the third
The voltage applied between H and H shown in FIG.

Furthermore, since the pair of nonlinear resistance elements 34a and 34b are arranged very close to each other, their characteristics can be considered to be almost the same, and the potential of the pixel electrode 36 moves around Vo during the selection period and the non-selection period. It turns out. The data to be displayed is determined by the potential difference between the pixel electrode 36 and the counter electrode 32, so by changing the potential of the counter electrode 32 by an amount corresponding to the data with vo as a reference, arbitrary display is possible, and grayscale etc. can be produced relatively easily. Furthermore, in such a driving method, the data signal is independent of the characteristics of the nonlinear resistance element, so even if there is some variation or change over time in the element characteristics, (2). .

If it is made large enough, stable driving can be achieved.

[Problem to be solved by the invention]

Display panels that use multiple nonlinear resistance elements for each pixel in this way enable larger display capacity and higher image quality, but - the large number of pixels forces the opposite electrode of the book. Therefore, the amount of charge charged in one pixel varies depending on the data written to other pixels in the same column during the non-selection period.

As is clear from Figure 2 (dl, (el), the amount of discharge is larger in Figure 2 tel for the nth row pixel even if the same ON state. Therefore, in the case of V# tone display, there is a difference in density. In order to reduce this difference, it is effective to reduce the discharge amount itself, but this requires increasing the resistance of the nonlinear resistance element when low voltage is applied, and increasing the capacitance C1 of the pixel section. It is necessary to increase the ratio Cp/CNt between CNL and the capacitance CNL of the element.Increasing the resistance of the element has a limit due to VOP etc.
Increasing CNL becomes difficult when the pixel size is small. Therefore, there is a problem that there is a limit to the level of gray scale that can be displayed.

Therefore, the present invention reduces the difference in discharge amount depending on the pattern of the data signal during the non-selection period, and reduces the capacitance ratio C of the pixel section and the element section.
It is an object of the present invention to provide a method for driving an electro-optical device that can relax restrictions such as the resistance value of a P/CM nonlinear resistance element.

[Means to solve the problem]

In order to solve the above problem, the present invention divides the selection period into two, uses the first half or the second half as a data charging period, and uses the remaining period to average the discharge amount.
This enables stable operation regardless of data patterns and loosens design constraints.

〔Example〕

Embodiments of the present invention will be described below based on the drawings. 1st
The drawings are drive waveform diagrams explaining the present invention in detail, and FIG. ) is n+1
A pair of row electrodes (driving electrodes) adjacent to the row pixel electrode
1 fc) is a scanning signal applied to the pair of rows (driving electrodes) adjacent to the n+2th pixel electrode, and 1+d) is a scanning signal applied to a pair of rows (driving electrodes) adjacent to the n+2th pixel electrode. The data signal applied to the column electrode (counter electrode) when )
FIG. 3 is a diagram illustrating data signals applied to; Figure 1 ta+~(
In C), it is shown that the driving electrodes 31 are selected line-sequentially one pair at a time. In this case, the period during which the potential difference between the pair of drive electrodes becomes the selection potential is 2 compared to FIG. 2, and data is charged here.
The period until the next row is selected is used to average the data. The time ratio between the charging period and the averaging period is V. , can be set arbitrarily depending on the balance. (If the charging period is short, it is better to set V slightly larger.) FIG. 1 1dl (el is an example of a data signal. That is, when the pixel is ON, the charging period is ■.N, and the averaging period is ■.

. When 41 pixels are OFF, V is applied during the charging period and V during the averaging period. 8 voltage is added as data. By doing so, the average potential of the data signal during the non-selection period becomes the same for all data patterns, and the amount of discharge becomes almost uniform. The data voltage V is ■ during the charging period. FF≦V,
≦If any value of VON is taken, enter ■ in the averaging period. N”VOFF v.

A similar effect can be obtained by adding the voltage as data. It goes without saying that the difference in tli can also be reduced by fixing the data of the averaging period to a constant value regardless of the data of the charging period.

〔Effect of the invention〕

As explained above, according to the present invention, one selection period is divided into a data charging period and a data averaging period, and by controlling the scanning signal and the data signal, the amount of charge discharged during the non-selection period can be reduced. can be averaged regardless of the data pattern, allowing for free design with respect to constraints such as the leakage characteristics of the nonlinear resistance element and the ratio of pixel capacitance to element capacitance.

[Brief explanation of drawings]

Fig. 1 is a drive waveform diagram explaining the present invention in detail, Fig. 2
al is a waveform diagram showing a scanning signal applied to a pair of rows adjacent to the n-th pixel electrode (driving electrodes); FIG.
is a waveform diagram showing a scanning signal applied to a pair of row electrodes (driving electrodes) adjacent to the pixel electrode in the fi+1 row, Fig. 1+C
I is a waveform diagram showing a scanning signal applied to a pair of row electrodes (driving electrodes) adjacent to the pixel electrode in the n+2th row;
) is a waveform diagram showing the data signal applied to the column electrode (counter electrode) when all the pixels in the − column are turned on, FIG.
l is a waveform diagram showing the data signal applied to the column electrode (counter electrode) when the pixel in the n-th row of one column is ON and all the remaining pixels are OFF, and Figure 2 is a conventional electro-optical device. FIG. 2 1al is a waveform diagram showing a scanning signal applied to a pair of row electrodes (driving electrodes) adjacent to the n-th pixel electrode; FIG. FIG. 2 is a waveform diagram showing a scanning signal applied to a pair of row electrodes (driving electrodes) adjacent to the pixel electrode of the (C1 is applied to a pair of row electrodes (driving electrode) adjacent to the pixel electrode of the n+2th row. FIG. 2 1al is a waveform diagram showing the scanning signal. FIG. 2 1al is a waveform diagram showing the data signal applied to the column electrode (counter electrode) when all the pixels in one column are turned on. FIG.
Figure 3 is a waveform diagram showing the data signal applied to the column electrode (counter electrode) when the pixel in the row is ON and all the remaining pixels are OFF. X-Y matrix parallel circuit diagram, Figure 3 (b
1 is a cross-sectional view showing the structure of an electro-optical device using a nonlinear resistance element. A... Counter substrate B...... Substrate 3L31a, 31b - 32... 33... 34a 34b -- 35a 35b -- 36... Row electrode (Drive electrode) Column electrode (counter electrode) Electro-optic material (liquid crystal) Nonlinear resistance element Nonlinear resistance layer pixel electrode

Claims (5)

[Claims] (1) Two opposing substrates and a material having an electro-optic effect sandwiched between the substrates, a large number of row electrode groups formed on one substrate and a large number of column electrode groups formed on the other substrate, at least one of them. It consists of a pixel electrode group arranged in a matrix on a substrate, and a plurality of nonlinear resistance elements provided for each electrode of the pixel electrode group, and each pixel electrode is As a method for driving an electro-optical device in which a first row (column) electrode is connected to a second row (column) electrode via a second nonlinear resistance element, the first and second row (column) In a driving method in which electrodes are selected line-sequentially one pair at a time, the selection period is divided into two, with the first half (second half) being a data charging period and the second half (first half) being a data averaging period. 1. A method for driving an electro-optical device, the method comprising controlling a data signal. (2) The potential of the scanning signal is the selection potential during the data charging period;
2. The method of driving an electro-optical device according to claim 1, wherein the data averaging period is at a non-selective potential. (3) When the data potential at which the pixel is turned on is V_O_N, and the data potential at which the pixel is turned off is V_O_F_F, and the data potential at which it is charged is V_D, the potential of the data signal is V_D during the data charging period, and V_D during the data averaging period. V_O_
3. The method for driving an electro-optical device according to item 2, wherein N+V_O_F_F-V_D. (4) The method for driving an electro-optical device according to item 2, wherein the potential of the data signal always takes a constant value between V_O_N and V_O_F_F during the data averaging period. (5) The constant potential of the data signal during the data averaging period is V_O_N, V_O_F_F or (V_O_N+
5. The method for driving an electro-optical device according to item 4, wherein the voltage is either V_O_F_F)/2.