JP2001021877A - Liquid crystal display panel - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent a light shielding layer in a nondisplaying region from being corroded by an electrochemical reaction in a liquid crystal display panel provided with a frame-shaped light shielding layer composed of a Cr family metal arranged on the nondisplaying region of one substrate. SOLUTION: A corrosion inhibiting barrier layer 17 composed of a dummy color filter is provided between a second light shielding layer 13 and a common electrode 15 in a nondisplaying region. Accordingly the second light shielding layer 13, coated with the corrosion inhibiting barrier layer 17, is prevented from being corroded even when the common electrode 15 is corroded by an electrochemical reaction due to a strong electric field expressed by an arrow in figure 1 or the like. Consequently no hole due to corrosion is made in the second light shielding layer 13, therefore unnecessary light leakage is prevented.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] The present invention relates to a liquid crystal display panel.

[0002]

2. Description of the Related Art FIG. 3 is a sectional view showing a part of an example of a conventional liquid crystal display panel. This liquid crystal display panel includes a lower glass substrate 1 and an upper glass substrate 11. In the display area on the upper surface of the lower glass substrate 1, a plurality of pixel electrodes 2 made of ITO arranged in a matrix, thin film transistors 3 connected to these pixel electrodes 2, respectively, and a scanning signal for supplying a scanning signal to the thin film transistors 3 are provided. A scanning line (not shown), a data line (not shown) for supplying a data signal to the thin film transistor 3, and the like are provided. In a non-display area on the upper surface of the lower glass substrate 1, wirings 4 connected to scanning lines, data lines, and the like are provided. An overcoat film 5 made of silicon nitride or the like is provided on the entire upper surface of the lower glass substrate 1 including the pixel electrode 2, the thin film transistor 3, and the wiring 4, and an alignment film 6 made of polyimide is provided on the upper surface.

In a display area on the lower surface of the upper glass substrate 11, a first light shielding film 12 is provided in a lattice shape, and in a non-display area on the lower surface, a second light shielding film 13 is provided in a frame shape. In this case, the two light shielding films 12 and 13 are formed of a metal such as Cr and Mo. In the case of Cr, for example, the upper glass substrate 1 is used.
A two-layer structure of a CrO layer and a Cr layer from one surface side is used to reduce the reflectance on the display surface side to improve the contrast.
In the display area on the lower surface of the upper glass substrate 11 including the first light-shielding film 12, red, green, and blue color filter elements 14R,
4G and 14B are provided. In this case, the outermost color filter element, for example, the outside of the rightmost color filter element 14 </ b> R in FIG. 3 is provided on the lower surface of the second light shielding film 13. Color filter elements 14R, 14
G, 14B and the entire lower surface of both light shielding films 12, 13
A common electrode 15 made of O is provided, and an alignment film 16 made of polyimide is provided on a lower surface thereof.

Then, the lower glass substrate 1 and the upper glass substrate 1
Reference numeral 1 is attached to each other via a sealing material (not shown). A liquid crystal 21 is sealed between the alignment films 6 and 16 of the two glass substrates 1 and 11 inside the sealing material.

In such a conventional liquid crystal display panel, a thermosetting resin such as an epoxy resin used as a sealing material has a certain degree of water permeability. Although a small amount, it may enter the liquid crystal 21 inside the sealing material. When such a phenomenon occurs, the liquid crystal 21 or the alignment films 6, 1
6 contains a large amount of ionic impurities, and a strong electric field is generated during driving between a part of the wiring 4 and the common electrode 15 in the non-display area as shown by arrows in FIG. Therefore, the common electrode 15 and the second light-shielding film 13 having a higher voltage may be corroded by an electrochemical reaction that occurs when a strong electric field is applied to moisture and ionic impurities.

[0006]

As described above, in the conventional liquid crystal display panel, the common electrode 15 and the second light shielding film 13 are provided.
May be corroded by an electrochemical reaction. When such corrosion occurs, a hole is opened in the second light-shielding film 13 to cause light leakage, and bubbles are generated in the liquid crystal 21, and in any case, the display quality is degraded. Further, when the above-described electrochemical reaction proceeds, the wiring 4 having a lower voltage may be corroded and disconnected. An object of the present invention is to prevent a light-shielding film in a non-display area from being corroded by an electrochemical reaction.

[0007]

According to the present invention, there is provided a liquid crystal display comprising: a light-shielding film made of metal provided around a display area of one substrate; and a wiring provided on a region of the other substrate facing the light-shielding film. In the display panel, a barrier layer for preventing corrosion is provided on at least a portion of the light-shielding film corresponding to a part of the wiring. According to the present invention, since the corrosion-preventing barrier layer is provided on at least a portion corresponding to a part of the wiring on the light-shielding film in the non-display region, the light-shielding film covered with the corrosion prevention barrier layer in the non-display region Can be prevented from being corroded by the electrochemical reaction.

[0008]

FIG. 1 is a sectional view showing a main part of a liquid crystal display panel according to a first embodiment of the present invention. In this figure, the same reference numerals are given to the same parts as those in FIG. 3, and the description thereof will be omitted as appropriate. This liquid crystal display panel is different from the case shown in FIG. 3 on the lower surface of the second light-shielding film 13 in the non-display area, that is, between the second light-shielding film 13 and the common electrode 15. Layer 1
7 is provided. In this case, the barrier layer 1 for corrosion prevention
7 is formed simultaneously with the formation of the color filter element using the same material as any of the color filter elements 14R, 14G and 14B. That is, the corrosion prevention barrier layer 17 is formed by the dummy color filter.

As described above, in this liquid crystal display panel, the corrosion-preventing barrier layer 17 is provided between the second light-shielding film 13 and the common electrode 15 in the non-display area. Even if the common electrode 15 having a higher voltage is corroded by an electrochemical reaction caused by an electric field or the like, the second light-shielding film 13 covered with the corrosion-preventing barrier layer 17 is not corroded. it can. As a result, a hole due to corrosion is not opened in the second light-shielding film 13,
Therefore, the display quality can be prevented from deteriorating without unnecessary light leakage. However, the common electrode 15
It is inevitable that air bubbles are generated in the liquid crystal 21 due to corrosion of the liquid crystal 21.

Next, a second embodiment of the present invention which can prevent corrosion of the common electrode 15 will be described with reference to FIG. In this liquid crystal display panel,
The difference from the case shown in FIG. 1 is that the common electrode 15 is provided mainly only in the display area. Common electrode 1 in this case
As a method of forming 5, an unnecessary portion may be removed by photolithography after forming the ITO film.
When a predetermined mask is used as a hard mask for ITO film formation, the number of steps can be prevented from increasing.

As described above, in this liquid crystal display panel, the common electrode 15 is provided mainly only in the display area, so that
Even if an electrochemical reaction occurs in the non-display area due to a strong electric field or the like indicated by an arrow in FIG. 2, the common electrode 15 does not corrode. As a result, no bubbles are generated in the liquid crystal 21 and a decrease in display quality can be prevented. Also in this case, the second light-shielding film 13 covered with the corrosion-preventing barrier layer 17 does not corrode.

In the above embodiment, the barrier layer 17 for preventing corrosion is provided with the color filter elements 14R, 14G, 14B.
Although the case where the color filter element is formed simultaneously with the formation of the color filter element by using the same material as the above, that is, the case where the color filter element is formed in one layer by any of the color filter materials has been described, the invention is not limited to this. You may. Although FIGS. 1 and 2 show that there is a gap between the corrosion-preventing barrier layer 17 and the color filter element 14R immediately on the left side, the gap is eliminated by overlapping. You may do so. Further, the formation region of the corrosion-prevention barrier layer 17 is not limited to the entire non-display region, but may be, for example, only the region where the strong electric field as described above occurs, that is, only the region corresponding to a predetermined part of the wiring 4.

[0013]

As described above, according to the present invention, the corrosion prevention barrier layer is provided on at least a portion corresponding to a part of the wiring on the light shielding film in the non-display area. Corrosion due to an electrochemical reaction can be prevented from occurring in the light-shielding film covered by the corrosion-preventing barrier layer, and a deterioration in display quality due to such corrosion can be prevented.

[Brief description of the drawings]

FIG. 1 is a sectional view of a main part of a liquid crystal display panel according to a first embodiment of the present invention.

FIG. 2 is a sectional view of a main part of a liquid crystal display panel according to a second embodiment of the present invention.

FIG. 3 is a partial cross-sectional view of an example of a conventional liquid crystal display panel.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Lower glass substrate 2 Pixel electrode 3 Thin film transistor 4 Wiring 11 Upper glass substrate 12 First light shielding film 13 Second light shielding film 14R, 14G, 14B Color filter element 15 Common electrode 17 Corrosion prevention barrier layer

Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat II (Reference) G09F 9/00 315 G09F 9/00 315A 9/30 349 9/30 349C (72) Inventor Junichi Fujisawa Ishikawa, Hachioji-shi, Tokyo 5 Casio Computer Co., Ltd., Hachioji Research Laboratories, Hachioji R & D Co., Ltd. F-term (reference) CA24 DA14 EA04 EA05 EA10 EB02 ED02 ED15 FA01 FA02 FB12 FB15 5G435 AA00 AA16 BB12 CC09 CC12 FF13 KK05

Claims (4)

[Claims] 1. A liquid crystal display panel in which a light-shielding film made of metal is provided around a display area of one substrate, and wiring is provided on a region of the other substrate facing the light-shielding film. A liquid crystal display panel, wherein a corrosion-preventing barrier layer is provided on a portion corresponding to a part of the light-shielding film. 2. A liquid crystal display panel according to claim 1, wherein a common electrode is provided on a display region of said one substrate and on said light shielding film including said corrosion preventing barrier layer. . 3. The liquid crystal display panel according to claim 1, wherein a common electrode is provided mainly only on a display area of said one substrate. 4. The invention according to claim 1, wherein a color filter is provided on a display area of said one substrate, and said corrosion-preventing barrier layer is formed by a dummy color filter. A liquid crystal display panel characterized by the following.