JPH02170123A - Driving method for liquid crystal display element - Google Patents

Abstract

PURPOSE:To obtain an excellent display even on a display element which has a disconnected electrode by supplying the disconnected electrode with a voltage which is different from other normal electrodes. CONSTITUTION:If a scanning electrode X2 has a disconnection (c), specially, closer to one end (a) than to the center part of the electrode X2, display dots on an electrode X2b from one end (a) and the opposite-side end part (b) to the disconnection point (c) decrease display brightness toward the disconnection point to generate a large contrast difference between the display dots on the electrode on the side of one end (a) and other normal electrodes. For the purpose, the electrode which is disconnected and the position of the disconnection are checked previously and the voltage which is different from other normal electrodes, e.g. the voltage generated by adding a specific correcting voltage corresponding to the length from the disconnection position to the end part is applied. Consequently, the contrast difference between the display dots on the electrode which is divided into two owing to the disconnection and the display dots on the other normal electric conductor is reduced as much as possible can be reduced greatly.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a method for driving a liquid crystal display element such as a liquid crystal display panel.

[Conventional technology]

Conventionally, for example, as shown in FIG.
In a dot matrix type liquid crystal display element in which the signal electrodes Y1 to Y6 intersect with each other and the intersections are used as display dots to perform various displays, each electrode X, -X, -Y,
It is common to supply voltage to Y6 from one end thereof.

Therefore, there is a problem that a uniform display cannot be obtained due to differences in contrast between the voltage supply side of each electrode and the display dots on the opposite side due to differences in the resistance values of the electrodes leading to each display dot. there were.

Therefore, as a means to solve the above-mentioned problems, the present applicant previously proposed in Japanese Patent Application Laid-open No. 56-46289 to supply voltage to each electrode from both ends thereof. By doing this, the resistance value of the electrode from each end to the display dot can be reduced to approximately half at most compared to the case where voltage is supplied from one side, and the difference in contrast described above can be reduced. We were able to reduce it by almost half. Furthermore, by supplying voltage to each electrode from both sides as described above, in the unlikely event that one of the electrodes, for example the scanning electrode X2 as shown in FIG.
It is now possible to drive even when there is a break (disconnection) C.

[Problem to be solved by the invention]

However, if there is a disconnection C in one of the electrodes X2 as described above, the electrodes
-X2b is supplied with voltage from the ends a and b, respectively. Therefore, if the above-mentioned disconnection point C is located closer to one end a side (including the terminal part) than the center of the electrode x2 as shown in Figure 2, then As the electrode X2b on the other end becomes longer and the display dots on the electrode Xzb approach the disconnection point, the display becomes thinner, and the display dots on the electrode χ2a and the display dots on other unbroken electrodes become thinner. There was a problem in that a large contrast difference occurred between the two.

The present invention has been made in view of the above-mentioned problems, and provides a method for driving a liquid crystal display element that can minimize the above-mentioned contrast difference and obtain a good display even when an electrode is disconnected. The purpose is to

[Means for Solving the Problems] In order to achieve the above object, the present invention provides a method for driving a liquid crystal display element in which voltage is supplied to electrodes disposed on the liquid crystal display element from both ends of the electrode, and the present invention provides a method for driving a liquid crystal display element. The present invention provides a method for driving a liquid crystal display element, characterized in that a voltage different from that of other electrodes that are not disconnected is supplied to the electrodes that are not disconnected.

[For production]

By supplying the disconnected electrode with a voltage different from that of other unbroken electrodes, for example, by adding a predetermined correction voltage depending on the length from the disconnection point to the end, the disconnection can be made into two. It is possible to minimize the contrast difference between the display dots on the divided electrodes and between the display dots on the electrode without any disconnection.

〔Example〕

Hereinafter, the present invention will be explained in detail by taking as an example a case where a Tonotomatolinks type liquid crystal display element having a disconnection in the scanning electrode X2 as shown in FIG. 2 is driven by supplying voltage from both ends to each electrode. Explain in detail.

If there is a disconnection C in the scanning electrode The display dots on the electrode X2b extending from the end of the line to the disconnection point C become thinner as it approaches the disconnection point, and there is a large display dot between the electrode X2a on the one end a side and the other electrodes with no disconnection. A contrast difference occurs.

Therefore, in the present invention, the electrode with a disconnection and the position of the disconnection are investigated in advance, and the disconnected electrode is given a voltage different from that of other electrodes that are not disconnected, for example, depending on the length from the disconnection point to the end. A voltage to which a predetermined correction voltage has been added is supplied.

FIG. 1 shows an example of the voltage waveform supplied to each scan electrode X, to X7 in the liquid crystal display element of FIG. The voltage waveform (+) in the same figure is one end a of scanning electrode x2.
(C) of the same figure shows the voltage waveform supplied to the other end of the scanning electrode χ2.

As shown in FIG. 1(a), predetermined scanning voltages V1 and 4 are alternately applied to the scanning electrodes X1 and X2 to X7 every frame, as shown in FIG. 1(a). Then, as shown in FIG. 5(b), a negative correction voltage Via/V4a, which is smaller by Δvh on the reference voltage Vs side than the voltages ■1 and ■4, is applied to one end a side of the scanning electrode X2 for a predetermined time period ta. The applied voltage is applied to the other end of the scanning electrode A voltage obtained by adding Vlb and V4b for a predetermined time width tb is applied. In the figure, ■2 and ■3 indicate non-scanning voltages.

The above voltage difference Δvh is appropriately set in consideration of the density displayed on the display dots on the scanning electrode X2, and is determined experimentally, for example. Further, the time widths ta and tb are appropriately set depending on the distance from the ends a-b of the scanning electrode X2 to the disconnection point C, that is, the length of the electrodes χ2a-X and b, which are separated by one at the disconnection point. Specifically, for example, the above electrode x2 b
The density of the display dots in the central part of the electrode X
The concentration of the display dot on a is the same as that of the electrode X2 in its vicinity.
It is sufficient that the density is approximately intermediate between the display dots on b and the display dots on the nearby unbroken electrodes.

The time width ta-tb of the above correction voltage is shown in FIG.
) is equal to the time width t of scanning voltages ■1 and ■4,
Only the voltage difference Δvh may be changed depending on the lengths of the electrodes X2a and X2b. Further, the correction voltage waveform may have a spike shape or other waveform shape.

In the above experimental example, the voltage supplied to both ends a and b of the disconnected electrode was corrected, but only the voltage supplied to one of the ends, for example, the end with a longer distance to the disconnection point C, was corrected. Good too. Furthermore, if the disconnection point is located approximately at the center of the electrode, it is not necessarily necessary to correct it.

Further, in the above embodiments, the case where there is a disconnection in the scanning electrode has been described as an example, but the same applies to the case where there is a disconnection in the signal electrode. Furthermore, it is applicable not only to dot matrix type display elements but also to various liquid crystal display elements.

〔Effect of the invention〕

As explained above, the present invention is capable of supplying a disconnected electrode with a voltage different from that of other unbroken electrodes, for example, a voltage in which a predetermined correction voltage corresponding to the length from the disconnection point to the end is added. Therefore, it is possible to minimize the contrast difference between the display dots on the electrode that is broken and divided into two and between the display dots on the other electrodes that are not broken.

Therefore, good display can be obtained even in a display element having a disconnected electrode, and the yield of the display element can be improved.

[Brief explanation of the drawing]

FIG. 1 is a waveform diagram showing an example of a voltage waveform supplied to a scanning electrode in a dot matrix type liquid crystal display element, and FIG. 2 is an explanatory diagram showing the arrangement of electrodes in a dot matrix type liquid crystal display element. X, ~Xo are scanning electrodes, Y1~Yka are signal electrodes, a-b
is the electrode end, C is the disconnected part, ■1・Vla・v4・V4a
is the scanning voltage, and ■2 and ■3 are the non-scanning voltages. 13F

Claims (2)

[Claims] (1) In a method of driving a liquid crystal display element in which voltage is supplied to the electrodes disposed on the liquid crystal display element from both ends thereof, a different voltage is supplied to the broken electrode than to other unbroken electrodes. A method for driving a liquid crystal display element, characterized in that: (2) Claim (1) characterized in that the voltage to be supplied to the disconnected electrode is a voltage to which a predetermined correction voltage corresponding to the length of the electrode from the disconnection point to the end is added.
) The method for driving the liquid crystal display element described in