JP2917538B2 - Liquid crystal display - Google Patents

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,
In particular, the present invention relates to a structure for preventing leakage of a sealing material for hermetically sealing a liquid crystal material between two flat substrates.

2. Description of the Related Art A display device using a liquid crystal material whose light transmittance changes by application of an electric field has been used for some time. recent years,
A dot display type liquid crystal display device has been used as a display device of a laptop personal computer or a word processor, and the screen has been rapidly increased in size and density, and the pixel size has been reduced.

A liquid crystal display device has a structure in which liquid crystal is sandwiched between two transparent insulating substrates on which electrodes and an alignment film are laminated, and a dot display type is a simple matrix type according to a method of driving pixels. It is classified into the active matrix type. The simple matrix type has a structure in which a plurality of strip-shaped transparent electrodes are arranged in the X direction and the Y direction with a liquid crystal interposed therebetween, and the active matrix type has a thin film transistor (TFT) arranged in a matrix on a transparent electrode provided for each pixel.
Is a structure for applying an electric field. Hereinafter, the liquid crystal display devices described in this specification are of the matrix type.

In the case of increasing the size of the display screen and increasing the density thereof, in the simple matrix type, it is difficult to realize a high quality display because the thinning of the strip-shaped electrodes directly leads to a decrease in the electric field applied to the liquid crystal. Most large-screen liquid crystal display devices are of the active matrix type.

[0005]

2. Description of the Related Art The technical problem of the present invention relates to a normal manufacturing process of a liquid crystal display device.
This step will be briefly described with reference to (c).

(A) In FIGS. 1 and 2, reference numerals 1 and 2 denote glass substrates to which an alignment film is adhered. TFTs, transparent electrodes and the like (not shown) are formed in at least one display area 3 of the substrate.
The sealing material 4 is applied so as to surround the display area. Usually, a thermosetting epoxy resin is used for the sealing material. The application pattern is rectangular but not completely closed, and a notch 9 serving as a liquid crystal injection port is provided in a subsequent process.

Next, as shown in FIG. 2 (b), two substrates are superposed and bonded. In this process, these substrates are sealed in a soft plastic bag in a vacuum chamber and then outside the chamber. Heating is performed while applying pressure by atmospheric pressure to cure and adhere the sealing material. In addition, in order to keep the distance between the substrates constant, small resin spheres having a diameter of about 5 μm are dispersed in the display area, but this is not directly related to the technical problem of the present invention and is not shown.

Atmospheric pressure is also used when injecting liquid crystal into this substrate structure. When the opening of the sealing material of the structure is immersed in the liquid crystal bath 10 in a vacuum chamber to leak the atmosphere and increase the surrounding pressure, the liquid crystal material is injected into the space defined by the sealing material. This state is schematically shown in FIG.
After injecting the liquid crystal, the opening is closed and the liquid crystal is sealed in the display area.

[0009]

Since the above-described process of bonding two substrates is performed in a vacuum, if fine air bubbles are entrapped in the uncured sealing material, the pressure of the air in the air bubbles may be reduced. As a result, the bubbles expand. Even when the bonding is not performed in a vacuum, the bubbles expand thermally during the heat treatment for curing.

There is no problem if the shape of the expanded bubble is spherical or circular, but it may extend in a specific direction according to the shape of the surrounding solid matter, and if the direction crosses the sealing material. Problems arise.

That is, air bubbles extend across the sealing material,
If both ends are connected to the outside, a ventilation hole that penetrates the sealing material will be opened, but if such a ventilation hole exists, the air leaks in the liquid crystal injection step using atmospheric pressure, so the liquid crystal Will not be completely injected.

In a matrix type liquid crystal display device, a large number of strip-shaped electrodes are arranged across the seal material. When bubbles expand along the electrodes, through holes are generated in the seal material as described above.

In a simple matrix type display device, the electrodes covered with the sealing material are thinner than the distance between the substrates.
Although the direction of expansion of the bubble is given priority to the direction along the electrode, there is still room for the bubble to spread on the electrode, so that it often cannot penetrate the sealing material. On the other hand, in the case of the active matrix type, since the thickness of the electrode is large, the gap on the electrode is small, and the interval between the electrodes is narrow, the bubble expands and extends almost only in the direction parallel to the electrode. Therefore, a through hole is easily generated. This situation is shown in FIG. 3 and will be described below with reference to FIG.

1A and 1B are views showing a portion where a through hole is formed in a sealing material. FIG. 1A is a plan view, and FIG. 1B is a cross-sectional view along XX '. 1 and 2 are substrates, and 5 and 6 are electrodes. The gap between the two substrates is about 5 μm, whereas the thickness of the electrode often exceeds 2 μm, so the gap on the electrode is less than 3 μm. Become. The distance between the electrodes is about 50 μm.

Considering the situation where bubbles exist between the electrodes and expand, considering that bubbles are present in a highly viscous epoxy resin,
15 spreads little in the gap of 3 μm, but only in the gap of 5 μm, so that the bubble extends in the direction traversing the sealing material 4,
As shown, pores penetrating the sealing material are formed.

The active matrix method is suitable for increasing the size and density of a liquid crystal display device. However, if the power supply lines and bus lines increase in resistance as they become thinner and longer, the signal waveform becomes distorted. Since display unevenness occurs, the electrodes are required to have the lowest possible resistance in order to suppress them, and the demand to increase the thickness of the electrodes is expected to increase in the future. The problem of leak hole generation must be resolved immediately.

An object of the present invention is to provide an electrode having a shape in which the generation of bubbles penetrating the sealing material due to such a situation is suppressed even in a liquid crystal display device using a thicker electrode. Another object of the present invention is to provide a liquid crystal display device in which a predetermined space is completely filled with a liquid crystal material.

[0018]

In order to achieve the above object, a liquid crystal display device according to the present invention is characterized in that a band-shaped electrode existing through a seal material defining a liquid crystal sealing space is formed in an area covered by the seal material. Has a reduced thickness portion.

Such an electrode shape allows room for air bubbles taken in the sealing material to spread in directions other than the direction parallel to the electrode.

[0020]

FIG. 1 is a view showing a basic structure of the present invention.
Hereinafter, the operation and effect of the present invention will be described with reference to the drawings.

2A and 2B show the structure of the portion where the electrode of the present invention crosses the sealing material. FIG. 1A is a plan view, and FIG.
X 'is a cross-sectional view, and (c) is a YY' cross-sectional view. Similar to the prior art, reference numerals 1 and 2 denote substrates. The case where the distance between the substrates is about 5 μm, the thickness of the strip-shaped electrodes 6 and 7 is 3 μm, and the distance between the electrodes is about 50 μm will be considered.

A feature of the present invention is that a thinned region 8 is provided in a portion of the electrode covered with the sealing material 4. In this region, the thickness of the electrode is about 1 μm, and its length is about 200 μm. Assuming a situation in which bubbles 15 are generated in a sealing material portion sandwiched between electrodes having such a shape, bubbles are generated in a direction parallel to the electrodes in a portion where the thickness of the electrode is large, as in the conventional structure. spread. However, when the spread reaches the thin part of the electrode, it begins to spread on the electrode because there is a sufficient gap here.

In the case where the spreading direction is not limited to one direction, since the surface tension acts to shorten the peripheral length of the bubble, the planar shape becomes almost circular, and the bubble is formed only in the direction parallel to the electrode. The tendency to spread is eliminated, and the formation of an opening through the sealing material is suppressed.

[0024]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention is an active matrix type liquid crystal display device in which the electrodes constituting bus lines have a two-layer structure of chromium (Cr) and aluminum (Al). The conceptual shape is the same as that shown in FIG. 1, but FIG. 2 partially shows this electrode shape in a perspective view. Here, the electrode 6 has a thickness of 2 nm on the 300 nm Cr layer 61.
An Al layer 62 having a thickness of 000 nm is superposed, and the upper layer Al is removed over a length of 200 μm in the thinned region 8 located substantially at the center of the sealing material, leaving only the Cr layer.

A sealing material is applied to the glass substrate on which the above-mentioned electrodes are formed by screen printing, the other substrate is overlaid, and a heating process is performed according to the processing method described in the section of the prior art, thereby completing the bonding process.

[0026]

As described in the section of the operation, by adopting the electrode structure of the present invention, even if air bubbles are present in the sealing material applied to intersect with the strip-shaped electrode, the air bubbles cause the sealing material to be removed. It does not expand so as to penetrate, and the airtightness of the liquid crystal filling space can be improved. Also, the increase in resistance due to the thinning of the electrodes has little effect because the length of the thinning is small, and the effect of lowering the resistance caused by making the electrodes thicker is sufficiently large. is there.

[Brief description of the drawings]

FIG. 1 is a diagram showing the basic structure of the present invention.

FIG. 2 is a perspective view showing a structure of an electrode according to the embodiment.

FIG. 3 is a diagram illustrating a problem of the related art.

FIG. 4 is a diagram showing a manufacturing process of the liquid crystal display device.

[Explanation of symbols]

 1, 2 Substrate 3 Display area 4 Sealing material 5 Bubbles 6, 7 Electrode 8 Thinned area 9 Notch 10 Liquid crystal bath 61 Cr layer 62 Al layer

Continued on the front page (72) Inventor Kunio Furukawa 1015 Uedanaka, Nakahara-ku, Kawasaki City, Kanagawa Prefecture Inside Fujitsu Limited (72) Inventor Yoshishiro Katayama 1015 Kamiodanaka, Nakahara-ku, Kawasaki City, Kanagawa Prefecture Fujitsu Limited (56 References: Japanese Utility Model Application, Sho 59-166224 (JP, U) (58) Fields investigated (Int. Cl. ⁶ , DB name) G02F 1/1345 G02F 1/1339 505 G02F 1/1343

Claims (4)

(57) [Claims] 1. A liquid crystal display device comprising a liquid crystal sealed between two flat plates, wherein a band-shaped electrode extending through a seal material defining a liquid crystal sealed space is provided. Oite belt-shaped collector in the covered position in wood
The liquid crystal display device, characterized in that is to have a thin layer region across the pole. 2. The method according to claim 1, wherein the strip electrode includes a lower electrode and an upper electrode.
No laminated electrode der is, the width of the lower layer electrode and upper layer electrode is substantially equal
Ku, the upper layer electrode in position covered with the sealing material
2. The liquid crystal display device according to claim 1, wherein the liquid crystal display device is removed . 3. The method according to claim 1, wherein the lower electrode is made of chromium (Cr).
Serial upper electrode and characterized in that the A aluminum (Al)
Liquid crystal display device. 4. A thin film provided for each pixel, wherein said strip-shaped electrode is provided.
It is characterized by controlling the operation of the transistor
Liquid crystal display device.