JPH049920A - Method for driving opto-electrical device - Google Patents

Abstract

PURPOSE:To average the current direction of a non-linear resistor element, to extend the using life of respective elements and to make it possible to control storing characteristics by inverting and driving the selected potential of a scanning signal in each frame. CONSTITUTION:Many driving electrodes 31a, 31b are successively selected as a pair from the highest position, and during the selection period, data are charged by counter electrodes 32. In this case, the selecting potential of a scanning signal is inverted and driven in each frame. Since the current direction of a current flowing into non-linear resistor elements 34a, 34b are averaged so as not to be deflected to one direction, the using life of the non-linear resistor elements can be extended and the generation of a picture element defects can be suppressed. In addition, the charge/discharge of data can easily be controlled by inverting the non-selected potential.

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 electrode.

[Summary of the Invention] In the present invention, 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. When driving an electro-optical device, in a method of driving while selecting drive electrodes line-sequentially one pair at a time, driving is performed by inverting the selection potential of a scanning signal every frame. In addition to ensuring that the direction of current flowing through the nonlinear resistance element is not biased in one direction, the life of the element is extended.
An object of the present invention is to provide a method for driving an electro-optical device in which charging and discharging of data can be easily controlled by inverting a non-selective potential.

[Conventional technology 1] As a thin, lightweight, and low power consumption display panel,
Liquid crystal display panels have excellent characteristics and are currently widely used in laptops, book-type personal computers, and the like. Among these, active matrix display panels are attracting attention as a method that can increase the amount of displayed information and improve image quality. As active elements, three-terminal elements using thin film transistors, MIM, etc.
There are two-terminal elements represented by nonlinear resistance elements such as , 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.

Further, in the case of diodes, there are 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.

FIG. 3(a) is an X-Y matrix panel circuit diagram of an electro-optical device using a nonlinear resistance element, and FIG. 3(b)
FIG. 2 is a partial cross-sectional view showing the structure of the device. Usually about 100 to 1000 row electrodes (driving electrodes) 31 and column electrodes (counter electrodes) 32 are formed on the substrate B and the counter substrate A, respectively. The X-Y intersection has a pixel electrode 36 and a plurality of nonlinear resistance elements 34a, 34b for each pixel electrode 36, which are connected to two different drive electrodes 31a, 31b, respectively. An electro-optic material 33 is held between substrates A and B.

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, and data is charged by the opposing electrodes within the selection period. FIG. 2 shows driving waveforms of a conventional electro-optical device, and FIG. 2(a) shows a scanning signal applied to the first driving electrode 31a, and FIG.
) shows the scanning signal applied to the second driving electrode 31b, and FIGS. 2(c) and 2(d) show the waveform of the data signal applied to the counter electrode. In FIG. 2(a), the potential of the first driving electrode 31a is ■ during the non-selection period. +V, and during the selection period, Vo+Vo.

6 In FIG. 2(b), the second drive electrode 3
1b is ■ in the non-selection period. -Vl, potential, V during the selection period
. -V6. ′ potential. Therefore, the voltage applied across the pair of nonlinear resistance elements 34a and 34b (between (a) and (b) shown in FIG. 3(a)) is V, +V during the non-selection period.
. , during the selection period V 60 + V0. So, v, +
If y is made sufficiently small and V On+v, , ,' is made sufficiently large, the nonlinear resistance elements 34a and 34b will work as switches. Further, vo indicates the potential of the pixel electrode 36 during the selection period, and ■. ,/V,,′,
If the ratios of V and /Vゎ are equal, the potential of the pixel electrode 36 is V even during the non-selection period. will be centered around. 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 gray Scales etc. can also be taken out relatively easily. FIG. 2(c) shows the waveform of the data signal applied to the counter electrode 32 when all the pixels in the − column are turned on, and FIG. 2(d) shows the waveform of the data signal applied to the counter electrode 32 when all the pixels in the − column Only ON
This shows the waveform of the data signal applied to the counter electrode 32 when all the remaining signals are turned off. In such a driving method, the data signal is transmitted through the nonlinear resistance element 34.
Since it is independent of the characteristics of a and 34b, even if there is some variation in the element characteristics within the panel surface, V op+
If V op' is set sufficiently large, it can be driven without any problem.

[Problems to be Solved by the Invention] In this way, a display panel using a plurality of non-linear resistance elements for each pixel allows for larger display capacity and higher image quality, but with conventional driving methods, Since the current flowing through the nonlinear resistance element during the selection period is always unidirectional, and this tendency also exists during the non-selection period, the characteristics of the element tend to change over time, and the lifespan until breakdown tends to be shortened. Therefore, pixel defects are likely to occur, resulting in reliability problems.

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to provide a method for driving an electro-optical device that can extend the life of a nonlinear resistance element and suppress the occurrence of pixel defects.

[Means for Solving the Problems] In order to solve the above-mentioned problems, the present invention inverts the selection potential of the scanning signal every frame so that current flows in both directions through the nonlinear resistance element. The aging characteristics of the material are improved.

〔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. FIG. 1(a) shows the waveform of the scanning signal applied to the first driving electrode 31a, and FIG. 1(b) shows the waveform of the scanning signal applied to the second driving electrode 31b. FIGS. 1(c) and 1(d) show the waveforms of the scanning signals applied to the counter electrode 32. FIGS. In FIG. 1(a), the potential of the first driving electrode 31a is V during the non-selection period. It is maintained at 10v4, and i:Vo+V every frame during the selection period. , , Vo-Vo are repeated. Figure 1 (
In b), the second drive electrode 31b is set to V during the non-selection period.
o-Vb potential, during the selection period Vo - every 17 rays 4
V6p', Vo + V. The potential becomes p'. Therefore, the voltage applied to both ends of the pair of nonlinear resistance elements 34a and 34b (between (a) and (b) shown in FIG. 3(a)) is 2 during the non-selection period.

10■ゎ, v02+V op every frame during the selection period
', V6pVI+,', and the direction of the current flowing through the nonlinear resistance element is switched every frame. Further, the potential of the pixel electrode 36 is V. The waveform of the data signal (the first
Figures (c) and (d)) show the conventional waveforms (Figure 2 (c) and (d)).
)) is similar.

FIG. 4, FIG. 5, FIG. 6, and FIG. 7 are drive waveform diagrams for explaining the second, third, fourth, and fifth embodiments of the present invention, respectively, and (a) in each figure is First drive electrode 31a
(b) of each figure shows the waveform of the scanning signal applied to the second
The waveform of the scanning signal applied to the drive electrode 31b in each figure (
C) and (d) each show the waveform of the data signal applied to the counter electrode 32. In these examples, the non-selection potential is also inverted. That is, FIGS. 4 and 5 show inversion before and after selection, FIG. 6 shows inversion for each frame, and FIG. 7 shows inversion for each selection pulse width. By doing so, the direction of the current flowing through the nonlinear resistance element is more averaged.

Furthermore, although the non-selection period is a period during which data is held, the holding characteristics can also be adjusted by the timing at which the non-selection potential is inverted. Therefore, it goes without saying that there are various methods of inverting the non-select potential in addition to those shown here.6 [Effects of the Invention] As explained above, according to the present invention, the selection potential of the scanning signal and the non-select potential can be inverted. By inverting the selection potential, the direction of current flowing through the nonlinear resistance element can be averaged, making it possible to extend the life of the element and control the retention characteristics. Figures 8 and 9 show the aging characteristics of the nonlinear resistance element by the conventional driving method and the driving method of the present invention, respectively. These are the results of measuring changes in characteristics over time. In the conventional driving method, the characteristics start to change from the l O' cycle position, and the I
In the O"cycle, the current shifts by about half an order of magnitude at a voltage of 20V, whereas in the case of the driving method of the present invention, the current shifts by about half an order of magnitude with a voltage of 20V.
There is almost no change in the characteristics even after the cycle is applied, and the reliability is significantly improved.

[Brief explanation of drawings]

FIG. 1 is a drive waveform diagram explaining the present invention in detail. FIG. 1(a) is a diagram showing the waveform of a scanning signal applied to the first driving electrode, and FIG. FIG. 1(C) is a diagram showing the waveform of the scanning signal applied to the driving electrode. FIG. , only one of the pixels in the - column is ON,
Figure 2, which shows the waveform of the data signal applied to the counter electrode when all the remaining ones are OFF, is a drive waveform diagram of a conventional electro-optical device, and Figure 2(a) is the first drive waveform. FIG. 2(b) is a diagram showing the waveform of the scanning signal applied to the electrode. FIG. 2(C) is a diagram showing the waveform of the scanning signal applied to the second driving electrode. FIG. 2(C) is a diagram showing the waveform of the scanning signal applied to the second driving electrode. Figure 2 shows the waveform of the data signal applied to the counter electrode when
Figure 3(a) is a diagram showing the waveform of the data signal applied to the counter electrode when all the remaining ones are turned off. b) is a sectional view showing the structure of an electro-optical device using a nonlinear resistance element, FIG. 4 is a drive waveform diagram explaining the second embodiment of the present invention, and FIG. FIG. 4(b) is a diagram showing the waveform of the scanning signal applied to the driving electrode. FIG. 4(C) is a diagram showing the waveform of the scanning signal applied to the second driving electrode. FIG. Figure 4(d) is a diagram showing the waveform of the data signal applied to the counter electrode when the pixel is turned on, and only one of the pixels in the - column is turned on.
FIG. 5 is a diagram showing the waveform of the data signal applied to the counter electrode when all the remaining ones are OFF, and FIG. 5 is a drive waveform explaining the third embodiment of the present invention. Figure 5(b) shows the waveform of the scanning signal applied to the first driving electrode. Figure 5(C) shows the waveform of the scanning signal applied to the second driving electrode. Figure 5(d) is a diagram showing the waveform of the data signal applied to the counter electrode when all the pixels are turned on, and only one of the pixels in the - column is turned on.
FIG. 6 is a diagram showing the waveform of the data signal applied to the counter electrode when all the remaining signals are OFF, and FIG. 6 is a drive waveform diagram for explaining the fourth embodiment of the present invention. FIG. FIG. 6(B) is a diagram showing the waveform of the scanning signal applied to the first driving electrode. FIG. 6(C) is a diagram showing the waveform of the scanning signal applied to the second driving electrode. FIG. Figure 6(d) is a diagram showing the waveform of the data signal applied to the counter electrode when all of the pixels in the - column are ON, and only one of the pixels in the - column is ON.
FIG. 7 is a diagram showing the waveform of a data signal applied to the counter electrode when all the remaining signals are OFF, and FIG. 7 is a drive waveform diagram for explaining the fifth embodiment of the present invention. FIG. 7(b) is a diagram showing the waveform of the scanning signal applied to the first driving electrode. FIG. 7(C) is a diagram showing the waveform of the scanning signal applied to the second driving electrode. FIG. 7(d) is a diagram showing the waveform of the data signal applied to the opposing m poles when all of the pixels are turned on, and only one of the pixels in the - column is turned on.
Figure 8 is a diagram showing the waveform of the data signal applied to the counter electrode when all the remaining ones are turned off. Figure 8 is a diagram showing the aging characteristics of a nonlinear resistance element according to the conventional driving method of an electro-optical device. FIG. 2 is a diagram showing the temporal deterioration characteristics of a nonlinear resistance element according to the method for driving an electro-optical device of the present invention. A...Counter substrate B......Substrates 31, 31a, 31b, rows as poles (driving electrodes) 32...
・ 33 ・ ・ ・ ・ ・ 34a, 34b - 35a, 35b ・ 36 ・ ・ ・ ・ ・Column electrode (counter electrode) ・Electro-optical material (liquid crystal) ・Nonlinear resistance element ・Nonlinear resistance layer Pixel electrode Applicant: Seiko Electronics Kogyo Co., Ltd. Agent Patent Attorney Takayuki Hayashi Diagram Alx Diagram (b) $ Invention 3rd ω Higashi Torakotsu It is proposed that r moving criminal diagram Figure 5 Second draft of Honsaraguchi (Dynamic waveform chart Fig. 4 The 4th ω of the present invention A solid dynamic breaking paper diagram that reveals the history of the prison cell) Fig. 6 Rod diagram Cycle Clog N] Fig. Cycle [log N Ko No. figure

Claims (4)

[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 potential of the scanning signal is set to 1.
A method for driving an electro-optical device, characterized in that driving is performed by inverting each frame. (2) The method for driving an electro-optical device according to item 1, characterized in that driving is performed by inverting the non-selection potential of the scanning signal before and after selection. (3) The method for driving an electro-optical device according to item 1, characterized in that driving is performed by inverting the non-selection potential of the scanning signal every frame. (4) The method for driving an electro-optical device according to item 1, characterized in that driving is performed by inverting the non-selection potential of the scanning signal at every fixed selection pulse width.