JPH012019A - Active matrix liquid crystal display element - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an active matrix liquid crystal display device using an active element substrate on which an active element is formed for each pixel as one substrate.

[Prior Art] Recently, flat displays have been actively developed to realize office automation equipment terminals, portable televisions, and the like.

As a means to achieve this, in a liquid crystal display element in which electrodes are arranged in a matrix, an active element is arranged near the intersection of the matrix electrodes, and this drives the liquid crystal display element in a manner similar to static drive. The matrix method is being actively researched and developed.

When an active matrix liquid crystal display element is constructed using such an active element substrate on which an active element is formed for each pixel as one substrate, the opposite substrate may be a substrate connected to the active element. It is sufficient that a counter electrode that can apply a voltage to the liquid crystal layer between the pixel electrode and the pixel electrode is formed.

An equivalent circuit diagram of such a liquid crystal display element is shown in FIG.

FIG. 2 shows an example in which a thin film transistor is used as an active element. In FIG. 2, 21 is a signal line (source line) for inputting signals to the thin film transistor;
Reference numeral 22 indicates a gate line for applying a voltage for selecting a thin film transistor, 23 indicates a thin film transistor for turning on and off a pixel, and 24 indicates a capacitor representing a capacitance component specific to the liquid crystal layer configured for each pixel. Note that this figure is m
By way of example only, two or more active elements may be formed in one pixel to provide redundancy and reduce the occurrence of defects, and a storage capacitor may be provided for each active element.

In this way, in order to sequentially scan the active element substrate and control the voltage applied to each pixel, it was sufficient to simply form a counter electrode solidly on the counter electrode substrate facing the active element substrate.

[Problems to be Solved by the Invention] However, when a counter electrode substrate with only a solid counter electrode formed thereon is used, foreign matter, dust, etc. This causes adhesion, which causes
A short circuit may occur between the counter electrode and the signal line or gate line on the active element substrate, causing a reduction in the manufacturing yield of liquid crystal display elements.

In particular, when we investigated the cause of such short-circuit defects, we found that they often occur at the sealing portion provided for bonding both substrates together.

If such a short circuit occurs, a line defect will occur when viewed as a liquid crystal display element.Such line defects are fatal to liquid crystal display elements, and may result in defective products. This results in the following.

[Means for Solving the Problems] The present invention has been made to solve the above problems, and consists of an active element substrate on which an active element is formed for each pixel and a counter electrode substrate on which a counter electrode is formed. In an active matrix type liquid crystal display element with a liquid crystal sandwiched between,
The counter electrode is formed only in a part facing a display part surrounded by a group of pixel electrodes connected to active elements, and a lead part for connecting the part facing the display part to the outside. The present invention provides an active matrix type liquid crystal display element.

A three-terminal element can be used as the active element formed on the active element substrate of the present invention, and a typical example is a thin film transistor formed on an insulating substrate such as glass or ceramic as described above. For example, it may be an active element such as a diode ring or a transistor formed on a single crystal substrate, and any device can be used as long as the counter electrode substrate is used as a common counter electrode.

Of course, two or more of these active elements may be formed in one pixel and connected in parallel, or one of them may be selected and connected, and each pixel may have a capacitor, color filter,
A light shielding film or the like may be provided. Furthermore, regarding the arrangement of pixels, pixels may be arranged in rows and columns, or diagonally, or a single pixel pattern may be divided into several patterns. . Outside of this,
Other configurations used in the active element substrate may be added within a range that does not impair the effects of the present invention.

Next, a description will be given with reference to the drawings.

FIG. 1 is a plan view showing a typical example of the present invention, FIG. 1(A) is a plan view showing pixels and wiring on an active element substrate, and FIG. 1(B) is a plan view showing a counter electrode substrate. FIG. 3 is a plan view showing a counter electrode of FIG.

In addition, in this Figure 1, pixels are scaled by 3× for ease of understanding.
Although only 12 pixels of 4 are drawn, the actual active element board has 64,000 pixels of 320 x 200, and each pixel is formed with a color filter of 3 colors.
For example, 92,000 pixels are used.

In this active element substrate l of FIG. 1A, a thin film transistor 2 is formed near the intersection of a signal line 3 and a gate line 4, and a drain electrode of the thin film transistor 2 is connected to a pixel electrode 5.

The display part surrounded by the pixel electrode group connected to the active element is a part surrounded by the outer periphery of each pixel electrode, and the inside of the pixel electrode group also includes the wiring and the active element part.

Wiring consisting of these signal lines 3 and gate lines 4 is drawn out from a display area surrounded by a group of 5 pixel electrodes connected to thin film transistors 2, which are active elements. This wiring passes through a sealed portion with the counter electrode substrate and is connected to an external terminal portion 6.

On the other hand, on the counter electrode substrate facing this active element substrate,
A counter electrode is formed. This counter electrode is usually 1n
A transparent electrode such as Js-SnOi, Snug, or ZnO is used, but a reflective metal electrode may be used, such as in the case of a reflective liquid crystal display element.

This counter electrode is connected to the thin film transistor 2 which is an active element.
It is formed only in a portion facing a display portion surrounded by a group of 5 connected pixel electrodes, and a lead portion for connecting the portion facing the display portion to the outside.

In this example, as shown in FIG. 1(B), the counter electrode substrate 7 has a rectangular portion 9 facing a display area surrounded by a group of pixel electrodes in which a counter electrode 8 is connected to an active element, and It consists of four lead portions 10 extending diagonally from near the four vertices of a rectangle for connecting to the outside.

These four lead portions 10 are connected to external connection terminals 11 with lead wires formed on the active element substrate by an inter-substrate conductive connection member made of adhesive or the like mixed with conductive particles.

Further, in this example, the counter electrode pattern is approximately the same shape as, and slightly larger than, the part facing the display part surrounded by the pixel electrode group of the active element substrate. This is done in consideration of the alignment accuracy with the active element substrate and the accuracy of pattern reduction by etching. It is preferable to do so. However, since the expansion of this pattern increases the risk of short circuit, it is preferable to keep it to the necessary minimum, and at least to prevent it from reaching the seal portion.

In addition, when the lead portion 10 conductively connects the substrates at the seal portion 13 or outside the seal, the electrode is extended to the seal portion or the outside thereof. Even in this case, the wiring of the active element substrate is prevented from overlapping at the seal portion where the lead portion of the counter electrode is extended. In this example as well,
This lead part is the 4th part of the rectangular part facing the display part.
The lead wire extends diagonally from the vicinity of the top of the lead, and at the portion where this intersects the seal portion, no electrode other than the lead wire that is conductively connected to the lead portion between the substrates is formed on the active element substrate side. Therefore, the signal line or gate line of the active element substrate and the counter electrode do not face each other in the seal portion, and the risk of short circuit is low.

Further, in this example, four lead portions are provided diagonally from each vertex, but it may be one lead portion or two lead portions. Even if it is taken out diagonally, it may be taken out not in a straight line, but in a 4-shape or an arc shape, as long as it does not face the signal line or gate line at least at the sealing part.

This counter electrode may be formed by a known method such as lithography or mask deposition, and does not require high precision such as patterning of active elements.

A known sealing material can be used for the sealing part, and usually the sealing material is printed in a desired shape and the two substrates are made to face each other.
The sealing material is cured and bonded by heating or UV irradiation.

By adopting such a configuration, even if foreign matter, dust, etc. get mixed in when the sealing pressure is applied, short circuits between substrates will not occur at the sealing portion, and the manufacturing yield can be improved.

Liquid crystal is injected into the liquid crystal cell thus manufactured, and the injection port is sealed with an IF to complete a liquid crystal display element. Of course, it is also possible to supply the liquid crystal onto the substrate before the seal crimping, and then perform the tool crimping.

Furthermore, in order to realize color display, a color filter consisting of three primary colors is formed on this counter electrode substrate, or a color filter is formed on the pixel electrode of the active element substrate, and color display is performed. is also easily possible.

Further, a light shielding film or a polarizing film may be formed on the inner surface of the substrate, and part or all of the drive circuit may be formed on the substrate at the same time.

[Function] In the present invention, the lead portion 10 of the counter electrode is connected to the seal portion 13.
It is made so that it does not overlap with the wiring of the active element board. In the example shown in FIG. 1, the lead portion extends obliquely from near the four vertices of the rectangular portion facing the display portion, and at the portion where it intersects with the seal portion, the active tooth r substrate side has this lead portion. No electrodes other than the lead wires that are conductively connected between the lead portion IO and the substrate are formed.

Therefore, even if foreign matter, dust, etc. get mixed in during the manufacturing process, short circuits may occur.Especially in the sealed area where there is a high risk of short circuits, the signal lines and gate lines of the active element board and the counter electrode are facing each other. This results in a low risk of short circuits and a high manufacturing yield.

[Example] Example 1 An active matrix type liquid crystal display element was manufactured with the configuration shown in FIG. 1, in which a thin film transistor was formed as an active element on a glass substrate.

The thin film transistor had an inverted staggered structure and was formed on a glass substrate using a conventional photolithography method to obtain an active element substrate. This pixel electrode is ITO(1nJs
−3nOi).

A polyimide film was laminated on the pixel electrode of this active element substrate, and this was rubbed to form an alignment film.

As a counter electrode substrate, a T
TO was deposited to a thickness of 70 nm by sputtering using a mask having openings in the pattern shown in FIG. 1(B).

At this time, the rectangular portion of the counter electrode was made to be approximately 1 mn+ larger than the display portion surrounded by the pixel electrode group connected to the active element.

A polyimide film similar to that laminated on the active element substrate was also laminated on this counter electrode substrate, and this was rubbed to form an alignment film.

A sealing material is printed around the active element substrate manufactured in this way, an inter-substrate conductive connection material is printed on the counter electrode substrate,
The electrode surfaces of both substrates were faced to each other and pressed together to form a cell, and liquid crystal was injected to manufacture a liquid crystal display element.

Ten liquid crystal display elements were manufactured at the same time, but no short circuit occurred between the counter electrode of the counter electrode substrate and the wiring of the active element substrate, and no line defects occurred.

On the other hand, in the liquid crystal display element of the comparative example in which the counter electrode of the counter electrode substrate was a solid electrode, a short circuit that appeared to be caused by dust occurred in one out of ten liquid crystal display elements.

[9! , Bright Effect 1 In the present invention, a counter electrode has a portion facing a display portion surrounded by a group of pixel electrodes connected to an active element, and a lead portion for connecting the portion facing the display portion to the outside. At least in the seal portion, the counter electrode is prevented from overlapping with the wiring of the active element substrate.

For this reason,! ! Even if foreign matter, S, etc. get mixed in during the two-manufacturing process, short circuits between the boards are unlikely to occur. Particularly in the sealed portion where there is a high risk of short circuit, the signal line or gate line of the active element substrate and the counter electrode do not face each other, so there is less risk of short circuit between the substrates, and the manufacturing yield is high.

The present invention can be applied in various other ways as long as the effects of the present invention are not impaired.

[Brief explanation of the drawing]

FIG. 1 is a plan view showing a typical example of the present invention, FIG. 1 (Δ) shows the pixels and wiring of the active element substrate, and FIG. 1 ([3) shows the counter electrode of the counter electrode substrate. shows. FIG. 2 is an equivalent circuit diagram of an active matrix liquid crystal display element r using thin film transistors as active elements. Active element substrate: 1 Thin film transistor: 2 Signal line: 3 Gate line = 4 Pixel electrode: 5 Terminal portion = 6 Counter electrode substrate: 7 Counter electrode 2 8 Iris 2 sections)■-

Claims (2)

[Claims] (1) In an active matrix type liquid crystal display element in which a liquid crystal is sandwiched between an active element substrate on which an active element is formed for each pixel and a counter electrode substrate on which a counter electrode is formed,
The counter electrode is formed only in a part facing a display part surrounded by a group of pixel electrodes connected to active elements, and a lead part for connecting the part facing the display part to the outside. Active matrix type liquid crystal display element. (2) A rectangular part facing the display part surrounded by a group of pixel electrodes whose counter electrodes are connected to active elements, and a lead part extending diagonally from near the apex of the rectangle to connect the rectangular part to the outside. An active matrix type liquid crystal display element according to claim 1, which is formed only with.