JPS6239425Y2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an electrode structure for preventing side etching of electrodes in a liquid crystal display device.

Liquid crystal display devices have been widely used in watches, desktop computers, games, and as display parts for measuring instruments, but many of them have electrodes that are shaped like letters, numbers, or designs in advance. It was a segment display system, and its display capabilities were naturally limited.

On the other hand, the dot matrix method, in which multiple dot-like electrodes are installed and the combination of these electrodes displays letters, numbers, or designs when the light is turned on, basically displays all letters, numbers, or designs. It has a display capability that is incomparable to the segment method. In order to take advantage of this advantage, dot matrix type liquid crystal display devices are required to be able to display a relatively large amount of information, and are larger than segment type liquid crystal display devices.

The electrode structure of a conventional dot matrix type liquid crystal display device is as shown in FIG. 1, in which a transparent conductive film of tin oxide, indium oxide, etc. is coated on a transparent flat glass plate 1, and a transparent electrode 2 for display is formed. However, as the size of the liquid crystal display device increases, the driving voltage decreases due to its resistance, which is a drawback. Therefore, a low resistance conductive metal film such as gold, silver, or aluminum is coated on the transparent electrode 2 to form the lead electrode 3 to prevent voltage drop. Further, the lead electrode 3 extends as it is to the outside of the transparent electrode 2, and serves as a contact electrode 4. This contact electrode 4 is an input terminal, and a metal film having good solderability, such as nickel, is coated thereon so that it is soldered to an output terminal on a polyimide film on which an integrated circuit is mounted.

As mentioned above, the contact electrode 4 is made of low-resistance conductive metal such as gold, silver, or aluminum. As shown in FIG. 2, a chromium film 5 is coated before coating the low resistance conductive metal film. Etching is performed to form the contact electrode 4, but at this time the chromium film 5 is severely side-etched as shown in FIG. 2, and the contact electrode 4, which is a low resistance conductive metal film, becomes suspended in the air. However, if mechanical stress or the like is applied to this portion, the contact electrode 4 will peel off, making it impossible to obtain an accurate shape. In addition, as shown in FIG. 3, a step is formed at the boundary between the contact electrode 4 and the lead electrode 3 due to the transparent electrode 2, and the strain generated in this portion increases the etching rate, resulting in a difference in the etching rate as shown in FIG. Lead electrode 3 and contact electrode 4
It also had the disadvantage that it could be cut. Furthermore, a chromium film 5 is coated between the contact electrode 4 and the flat glass plate 1 to improve adhesion. There was a request to measure improvement.

The present invention eliminates these drawbacks, and its purpose is to prevent side etching of the chromium film by changing the structure of the electrode, as well as to prevent breakage between the lead electrode and the contact electrode. The purpose is to improve adhesion to the base.

That is, as shown in FIG. 5, the transparent electrode 2, which is unnecessary on the contact electrode 4 portion for display purposes, is also coated under the contact electrode 4. As shown in FIG. 6, since the transparent electrode 2 is an oxide, the etching rate of the chromium film 5 is slowed down by the influence of this oxide, and side etching of the chromium film can be suppressed. In addition, as shown in FIG. 6, the lead electrode 3
There is no difference in level between the lead electrode 3 and the contact electrode 4, and it is possible to prevent the lead electrode 3 and the contact electrode 4 from being cut during etching. Furthermore, chromium film 5
Because of the strong adhesion between the chromium film and the transparent electrode 2, which is an oxide, it is possible to obtain a stronger adhesion than when directly coating the flat glass plate 1 with a chromium film.

As an example, FIG. 7 shows how much the side etching of the chromium film 5 differs between the flat glass plate 1 and the transparent electrode 2 when an indium oxide film is used for the transparent electrode 2 and gold is used for the contact electrode 4. This is a diagram showing the electrodes viewed from below through a flat glass plate 1. On the flat glass plate 1, the chromium film 5 is side-etched, and the chromium film 5 between the gold contact electrode 4 and the flat glass plate 1 is removed, and the contact electrode 4 is visible. In contrast, on the transparent electrode 2 using indium oxide, the chromium film 5 is hardly side-etched. Furthermore, no breakage occurs at the boundary between the contact electrode 4 on the transparent electrode 2 and the contact electrode 4 on the flat glass plate 1. Furthermore,
It was also confirmed that the adhesion between the contact electrode 4 and the base is better when the base is the transparent electrode 2 made of indium oxide than when the base is the flat glass plate 1.

Further, the present invention is naturally effective not only for dot matrix type liquid crystal display devices but also for segment type liquid crystal display devices having lead electrodes and contact electrodes.

As described above, by providing the transparent electrode also under the contact electrode, effects such as prevention of side etching of the chromium film, prevention of breakage between the lead electrode and the contact electrode, and improvement of adhesion of the contact electrode can be obtained.

[Brief explanation of the drawing]

Fig. 1 is a plan view showing the electrode structure of a conventional dot matrix type liquid crystal display device, Fig. 2 is a cross-sectional view showing a contact electrode with side-etched chromium film, and Fig. 3 is a boundary between the lead electrode and the contact electrode. FIG. 4 is a cross-sectional view showing the state where the boundary part is cut, FIG. 5 and FIG. 6 are a plan view and a cross-sectional view showing the electrode structure based on the present invention,
FIG. 7 is a plan view showing the difference in side etching between the conventional structure and the structure of the present invention, viewed from the back side of a flat glass plate provided with electrodes. 1 is a flat glass plate, 2 is a transparent electrode, 3 is a lead electrode, 4 is a contact electrode, and 5 is a chrome film.

Claims (1)

[Scope of utility model registration request] liquid crystal injected between at least two glass plates;
In a liquid crystal display device comprising a transparent electrode for display coated on the glass plate, a lead electrode for reducing resistance value further coated on the transparent electrode, and a contact electrode for an input terminal, the transparent electrode extends not only to the display section but also to the contact electrode section, and the contact electrodes are all present on the transparent electrode.