JPH07333573A - Liquid crystal display device - Google Patents

Abstract

PURPOSE:To keep the uniformity of gaps of dummy electrodes electrically isolated and to suppress the lighting of a unnecessary part by arranging the electrodes electrically isolated on a part incorporating a seal part and applying a scan signal pulse to arranged electrodes in the row and column directions of a substrate of a side where the electrode area is larger. CONSTITUTION:A transparent conductive film (ITO) is formed on surfaces of glass substrates 2, 3, and the ITO film is etched, and 400 pieces of belt like transparent electrodes 4, 5 prolonging in one direction are formed in the whole substrates 2, 3 respectively. Then, a rectangular shape dummy electrode 5 hanging on the seal part is formed on one side of the peripheral edge part of the substrate 2. Then, an external circuit 10, for applying the scan signal pulse to the transparent electrode 4 of the substrate 2 of the side where the dummy electrode 5 of a liquid crystal element 1 is formed, and the external circuit 11, for applying a data signal pulse to the transparent electrode 6 of the substrate 3, are terminal connected, respectively. Then, when the scan signal pulse is applied to the arranged electrodes of the substrate 2, a gap defect is prevented, and the abnormal lighting of the unnecessary part is prevented also.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a liquid crystal display device, and more particularly to a liquid crystal display device driven by a data signal pulse and a scanning signal pulse.

[0002]

2. Description of the Related Art An image display device using a liquid crystal display device is
A large number of row and column electrodes extending in one direction on each substrate and arranged at a predetermined pitch are arranged to face each other so as to be orthogonal to each other, and the minimum region partitioned by these row and column electrodes is defined as a pixel. A matrix type liquid crystal display device in which a nematic type liquid crystal composition is sandwiched between them is generally used.

Further, as a large-capacity, high-accuracy liquid crystal display device intended for television images, graphic displays, etc., each pixel is driven and controlled by each pixel so that high-contrast display without crosstalk can be performed. An active matrix type liquid crystal display device in which switching elements are arranged is also used.

In these liquid crystal display devices, an alignment layer is laminated on the electrodes of each of the two substrates, and the two substrates are arranged at a predetermined interval so that the alignment layers face each other.
The periphery of the substrate is sealed with a sealing material. In addition, a liquid crystal composition is sealed in a predetermined gap between the two substrates, and a predetermined potential difference is applied to the opposing electrodes to control the direction of the liquid crystal molecules so that each pixel is turned on and off. It has a display function.

From the basic operation of such a liquid crystal display device, it is required to maintain the distance between two substrates, that is, the gap at a predetermined constant distance at least in the effective display area. Therefore, the sealing material at the peripheral portion of the substrate also has an important function of keeping this gap constant.

However, this gap tends to become narrower due to the problem of response speed, and it becomes more difficult to keep the gap at a constant interval as the area of the effective display region increases. For this reason, a method is also used in which balls or fibers made of glass or plastic of a predetermined size are uniformly dispersed as an interposing material in the gap between the electrodes, and the same material is added to the sealing material. Here, the above-mentioned gap is not exactly the substrate interval but the electrode interval.

On the other hand, in order to drive such a liquid crystal display device, an array of electrodes is drawn out from one side of the end portion of the rectangular substrate and electrically connected to an external drive circuit. That is, the pulled-out array electrode is included in the seal portion on one side of the rectangular substrate peripheral edge.

That is, the side portion of the substrate from which the array electrodes are drawn has a larger gap than the other side portions by the thickness of the electrode. For this reason, the nonuniformity of the gap is compensated by changing the size of the gap material in the seal material to some extent or changing the sealing condition of the seal material.

[0009]

However, if there is a substantial gap in the inside of the substrate, particularly in the effective display area and the peripheral portion of the substrate, unevenness of the display is likely to occur due to the nonuniformity of the gap and the quality is deteriorated. Decrease productivity.
In particular, it is a big problem in a high-quality display with a large screen.

Therefore, as a countermeasure against such a problem,
Attempts have also been made to dispose electrically isolated dummy electrodes also in the seal portion on the side where the array electrodes are not drawn out so as to make the same gap inside the substrate. By doing so, distortion is unlikely to occur in the liquid crystal display element, and the controllability and uniformity of the gap are improved.

However, in the liquid crystal display device driven by the time-divisional drive by the line inversion drive, the phenomenon that the dummy electrode is turned on even though the dummy electrode is electrically isolated was observed. In such lighting of the dummy electrode, it is possible to partially cover the dummy electrode depending on the location, but it is difficult to cover all of the dummy electrode, and basically it is necessary not to light the unnecessary portion.

The present invention has been made in view of the above problems, and provides a liquid crystal display device in which the uniformity of the gap due to electrically isolated dummy electrodes is maintained and the lighting of an unnecessary portion is suppressed. With the goal.

[0013]

According to the present invention, a large number of electrodes extending in one direction and arranged in a row or column direction at a predetermined pitch are formed, and at least two layers including an alignment layer laminated on the electrodes are formed. A substrate and a liquid crystal display element in which the alignment layer is arranged to face each other at a predetermined interval and is sealed at a peripheral edge of the substrate via a sealing material, and a liquid crystal composition is sealed within the predetermined interval; In a liquid crystal display device in which a data signal pulse and / or a scanning signal pulse is applied to array electrodes in the column direction and / or in the liquid crystal display device, electrically isolated electrodes are arranged in a portion including the seal portion at the peripheral edge of the substrate, The above object is achieved by applying a scanning signal pulse to the array electrodes in the row and / or column directions on the substrate on the side where the area of the isolated electrodes is large.

[0014]

[Function] Generally, in the time-division drive matrix display system,
Line inversion drive is used in order to prevent dripping of the drive waveform and flicker phenomenon. That is, the polarity is changed every time a fixed number of lines are driven even within one frame.

The inventor of the present invention has investigated the phenomenon that the dummy electrode lights up even though the dummy electrode is electrically isolated, and found that such line inversion drive is the cause of abnormal lighting. .

That is, if a large change in voltage amplitude occurs at the time of polarity reversal despite being electrically isolated,
The isolated electrode provided on the opposite side through the gap is charged up and the light is turned on. Therefore, conversely, if the isolated electrode is provided on the electrode side of the substrate where the voltage wave height changes largely, no lighting occurs.

Most of the substrates of the liquid crystal display element are rectangular, and all four sides of the substrate are sealed, and there is a possibility that any one of the sides will cause abnormal lighting. Therefore, a dummy electrode is provided on the long side, which is the most effective measure against gap defects.
By applying a scanning signal pulse to the array electrodes on the substrate on which the dummy electrodes are formed, gap defects can be prevented and abnormal lighting of unnecessary parts can be prevented.

The substrate has a square shape, or has a structure of
When it is necessary to provide dummy electrodes on the four sides, the area of the dummy electrode on the side where abnormal lighting is likely to occur can be made smaller than the other area.

[0019]

The liquid crystal display device of the present invention will be described in detail below. FIG. 1 shows a schematic cross section of an XY matrix type liquid crystal display device which is an embodiment of the present invention. In FIG. 1, glass substrates 2 and 3 with an outer shape of 200 mm × 205 mm
A transparent conductive film (ITO) having a predetermined thickness is formed on the surface of the substrate by a sputtering method or the like.

Next, this ITO film is etched by a usual photolithography method to have a width of 0.40 mm and a pitch of
Strip-shaped transparent electrodes 4 and 6 each having a size of 0.45 mm and extending in one direction are formed on the entire substrate. At the same time, the width of the seal portion on one side of the substrate peripheral portion is 2 mm.
The rectangular dummy electrode 5 is formed.

The substrate 2 on which the electrodes 4 and 6 are formed
After depositing a polyimide thin film on the surface including the electrodes 3 and 3, rubbing treatment was performed to form alignment layers 7 and 8. At this time, the rubbing direction was set to 240 degrees when the liquid crystal display element 1 was formed.

A sealing material 13 including a glass cylinder having a diameter of 6 μm was applied along the peripheral edge of the substrate thus formed except for the liquid crystal injection port. Further, plastic beads having a particle size of 6 μm were uniformly dispersed as a gap material on the surface of the alignment layer 8 of the substrate 3.

Next, the alignment layers 7 and 8 of the substrates 2 and 3 are formed.
Are placed facing each other, and the sealing material is cured while applying pressure to the substrate 2
After bonding Nos. 3 and 3, ZLI manufactured by Merck Ltd. was used as a liquid crystal composition by a usual method from a liquid crystal inlet (not shown).
Liquid crystal display element 1 was prepared by injecting 0.72% of S-811 added to -2293, finally sealing the liquid crystal inlet with an ultraviolet curable resin, and attaching a predetermined polarizing plate to the outside of the substrate. To complete.

An external circuit 10 for applying a scanning signal pulse to the transparent electrode 4 of the substrate 2 on the side where the dummy electrode 5 of the liquid crystal display element 1 thus formed is formed, and the substrate 3
An external circuit 11 for applying a data signal pulse to each transparent electrode 6 is connected to each terminal by a usual method to complete a liquid crystal display device.

When the liquid crystal display device thus formed is driven by time-divisional driving by line inversion driving, there is no display unevenness due to a gap defect, and no abnormal lighting of an unnecessary portion occurs. was gotten.

[0026]

As described above, according to the present invention, an electrically isolated dummy electrode is formed in a portion including a seal portion at a peripheral portion of a substrate without increasing the number of steps as a countermeasure against a gap defect, and the electrical conductivity is improved. By applying a scanning signal pulse to the array electrode of the substrate on the side where the area of the isolated electrode is large, it is possible to effectively prevent abnormal lighting of an unnecessary portion, so that there is no display unevenness and it is uniform and good. A liquid crystal display device having display performance can be provided.

[Brief description of drawings]

FIG. 1 is a schematic cross-sectional view showing an XY matrix type liquid crystal display device which is an embodiment of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Liquid crystal display element 2 ... Substrate 3 ... Substrate 4 ... Transparent electrode 5 ... Dummy electrode 6 ... Transparent electrode 7 ... Alignment layer 8 ... Alignment layer 9 ... Liquid crystal composition 10 ... External circuit 11 ... External circuit 12 ... Gap material 13 ... Seal material

Claims (1)

[Claims] 1. At least two substrates, each having a plurality of electrodes extending in one direction and arranged in a row or column direction at a predetermined pitch, and on which an alignment layer is laminated, and at least two substrates, and the alignment layer. And a liquid crystal display element in which a liquid crystal composition is sealed at a peripheral portion of the substrate via a sealing material at a predetermined interval and a liquid crystal composition is sealed in the predetermined interval, and the array electrodes in the row and / or column direction are arranged. In a liquid crystal display device that applies a data signal pulse and / or a scanning signal pulse, electrically isolated electrodes are arranged in a portion of the substrate peripheral portion including the seal portion, and the area of the electrically isolated electrode is large. A liquid crystal display device, wherein a scanning signal pulse is applied to the array electrodes in the row and / or column direction of the substrate on the side of the liquid crystal display.