JPH08194212A - Liquid crystal display element - Google Patents

Abstract

PURPOSE: To prevent the enlargement of the area of a display part and the defective connection of an electrode pad part. CONSTITUTION: A pixel electrode 3 and a pixel switch element 2 are formed on a 1st glass substrate 1. A color filter 9 is formed on a 2nd glass substrate 8. A polymer-dispersed liquid crystal layer 12 is sandwiched between the 1st glass substrate 1 and the 2nd glass substrate 8. A light shielding film 6 is formed on one side of the 1st glass substrate 1 except an area corresponding to the pixel electrode 3. The light shielding film 6 is also formed in an area corresponding to the electrode pad part 4 formed on the outer peripheral part of the 1st glass substrate 1. The light shielding film 6 is a light reflection film.

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 using a polymer dispersed liquid crystal (PDLC) and having a light shielding film formed thereon.

[0002]

2. Description of the Related Art A conventional liquid crystal display device is disclosed in Japanese Patent Laid-Open No. 4-17.
As described in Japanese Patent Publication No. 27-27, a liquid crystal layer is sandwiched between a first glass substrate on which pixel electrodes and pixel switch elements are formed and a second glass substrate on which color filters are formed, On the glass substrate side, a light-shielding film for separating each pixel is formed in order to prevent color shift and color unevenness.

[0003]

However, according to the conventional liquid crystal display element as described above, the pixel electrode and the pixel switch element are formed on the first glass substrate side, while the color electrode is formed on the second glass substrate side. Since the filter is formed and the light-shielding film is formed around the color filter, the pixel electrode of the first glass substrate and the light-shielding film of the second glass substrate are accurately aligned when manufacturing the liquid crystal display element. For this reason, some positional deviation of both glass substrates is planned from the beginning, and the area of the light shielding film is made larger, in other words, the area of the color filter is made smaller.
Therefore, the conventional liquid crystal display device described above has a problem that the area of the display portion is reduced.

Further, a liquid crystal display device using a polymer dispersed liquid crystal (PDLC) is disclosed in Japanese Patent Publication No. 5-5338, in which a mixed liquid of a photocurable resin and a liquid crystal is used for two glass sheets. It is formed by sandwiching it between the substrates together with a spacer for controlling the gap, and irradiating the mixture with ultraviolet rays through glass to cure the mixture. During this UV irradiation, if the mixed liquid adheres to the electrode pad part formed on the outer peripheral part of one of the glass substrates, this mixed liquid is irradiated with the ultraviolet light and hardened, and then the electrode pad part is leaded. Poor connection is likely to occur when soldering wires or driver ICs.

The main object of the present invention is to provide a liquid crystal display device which solves the above problems and can increase the area of the display portion.

A further object of the present invention is to provide a liquid crystal display device capable of preventing poor connection of electrode pad portions.

[0007]

According to a first aspect of the present invention, a polymer-dispersed liquid crystal is provided between a first glass substrate on which a pixel electrode and a pixel switch element are formed and a second glass substrate on which a color filter is formed. In a liquid crystal display element constituted by sandwiching layers, a liquid crystal display element is characterized in that a light shielding film is formed on one surface of the first glass substrate except for a region corresponding to the pixel electrode.

According to a second aspect of the present invention, the light-shielding film is formed in a region corresponding to an electrode pad portion formed on the outer peripheral portion of the first glass substrate. Adopt a display element.

According to a third aspect of the invention, the liquid crystal display element according to the second aspect is adopted, wherein the light shielding film is a light reflecting film.

[0010]

According to the liquid crystal display element of the first aspect, since the light shielding film is formed on the side of the first glass substrate on which the pixel electrode is formed, the light shielding film is formed at the time of manufacturing the liquid crystal display element. The pixel electrode and the pixel electrode can be formed with high precision without positional deviation, and therefore, it is not necessary to increase the area of the light shielding film. Therefore, the area of the display portion can be increased.

According to the liquid crystal display device of the second aspect, the light-shielding film protects the electrode pad portion from ultraviolet irradiation, so that the mixed liquid adhering to the electrode pad portion does not harden and is easily removed by ethanol or the like. It is possible to connect a lead wire, a driver IC, or the like to the electrode pad portion by soldering or the like without causing connection failure.
Further, by making the light for pixel projection enter from the first glass substrate side, it is possible to prevent the characteristic change due to the light irradiation of the driver IC mounted by the pixel switch and the COG.

According to the liquid crystal display element of the third aspect, since the light other than the light necessary for image projection is reflected by the light shielding film which is the light reflecting film, the temperature rise of the liquid crystal, the pixel switch, etc. is minimized. Therefore, the load of cooling the liquid crystal display element can be reduced.

[0013]

An embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 shows the cross-sectional structure of the main part of the liquid crystal display element according to the first embodiment.

In FIG. 1, a pixel switch element 2 such as a TFT, a transparent pixel electrode 3 made of ITO or the like electrically connected to the pixel switch element 2, aluminum or the like is provided on one surface of a first glass substrate 1. Electrode pad section 4 consisting of
Further, a transparent insulating film 5 made of silicon nitride or the like is formed.

On the other surface of the first glass substrate 1, a light-shielding film 6 is formed except the region corresponding to the pixel electrode 3, and a transparent insulating film 7 is formed on the entire surface.
Here, the light-shielding film 6 may be either a light-absorbing film of chromium oxide or the like, or a light-reflecting film of aluminum or the like, but in order to prevent the characteristic change due to heat of the pixel switch element 2 or the like,
A light reflecting film is desirable. Also, the insulating film 7 may be omitted.

When forming the pixel electrode 3 and the light-shielding film 6 on the first glass substrate 1, a photolithography process used for manufacturing a semiconductor wafer is used to suppress the positional deviation between the two to 2 μm or less. Is easy.

A color filter 9, a transparent electrode 10 made of ITO or the like and a transparent insulating film 11 made of silicon nitride or the like are formed on the second glass substrate 8. Here, the color filter 9 is formed to be slightly larger than the light-shielding film 6, and a positional deviation occurs between the first glass substrate 1 and the second glass substrate 8 when the liquid crystal display element of FIG. 1 is manufactured. Even if this occurs, the area of the display portion (the portion of the lower surface of the first glass substrate 1 where the light shielding film 6 is not formed) is not reduced.

First glass substrate 1 and second glass substrate 8
A polymer-dispersed liquid crystal layer 12 is enclosed between and. The space between the first glass substrate 1 and the second glass substrate 8 is maintained by a spacer (not shown).

The polymer-dispersed liquid crystal layer 12 is formed by sandwiching a mixed liquid of a photocurable resin and a liquid crystal together with a spacer between the first glass substrate 1 and the second glass substrate 8 to form a first glass substrate. It is formed by polymerizing and curing the photocurable resin by irradiating ultraviolet rays from the substrate 1 side. In addition,
Ultraviolet rays are not directly radiated to the mixed liquid above the pixel switch element 2, but when the mixed liquid above the display portion is cured, the ultraviolet light is scattered at this cured portion. The liquid mixture above 2, etc. will also be cured, and the liquid mixture will be cured throughout.

At the time of this ultraviolet irradiation, since the electrode pad portion 4 is covered with the light-shielding film 6 as described above, the mixed liquid adhering to the electrode pad portion 4 in the mixed liquid injection step is directly irradiated with ultraviolet light. There is no. Therefore, the mixed liquid adhering to the electrode pad portion 4 does not harden and can be removed by washing with ethanol or the like. Therefore, when soldering a lead wire, a driver IC, or the like to the electrode pad portion 4, poor connection is less likely to occur.

An example of a mode of use of the liquid crystal display element configured as described above is to irradiate light from the first glass substrate 1 side and form an image based on the ON / OFF state of the pixel switch element 2 and the like. Let During this light irradiation, the pixel switch element 2
As a result, the light is blocked by the light-shielding film 6 even when a material having a light-sensitive characteristic such as amorphous silicon is used, and thus the pixel switch element 2 is directly irradiated with the light. Therefore, the characteristics of the pixel switch element 2 are unlikely to change. Also,
A driver IC or the like is attached to the electrode pad portion 4 by COG (Chip
Even when mounted by on-glass), the light is blocked by the light-shielding film 6, so that the driver IC is not directly irradiated with the light, and the characteristics of the driver IC are less likely to change. When the light-shielding film 6 is composed of a light-reflecting film,
Since the light-shielding film 6 hardly absorbs light, the temperature rise of the liquid crystal display element can be suppressed, and the characteristic change due to heat is less likely to occur.

As described above, according to the liquid crystal display element of the present embodiment, the light shielding film 6 is formed on the side of the first glass substrate 1 on which the pixel electrode 3 is formed. At the time of manufacturing, the light-shielding film 6 and the pixel electrode 3 can be formed with high precision without misalignment, so that it is not necessary to increase the area of the light-shielding film 6. Therefore, the area of the display portion can be increased. In addition, since the light-shielding film 6 protects the electrode pad portion 4 from ultraviolet irradiation, the mixed liquid adhering to the electrode pad portion 4 does not harden, and therefore a lead wire or a driver IC is connected to the electrode pad portion 4. It can be connected by soldering, etc. without causing defects. Further, even when the light-shielding film 6 which is the light-reflecting film is irradiated with ultraviolet rays, the light-shielding film 6 hardly absorbs heat, so that the heat is conducted from the light-shielding film 6 to the driver IC connected to the electrode pad portion 4. Therefore, it is possible to prevent the characteristic change of the driver IC or the like due to heat.

FIG. 2 shows a sectional structure of a liquid crystal display element according to another embodiment. The liquid crystal display element of this example is
The light-shielding film 6 is formed on the surface of the first glass substrate 1 on the pixel electrode 3 side, and this liquid crystal display element can also obtain the same effect as that of the liquid crystal display element of the above-mentioned embodiment. The other reference numerals in FIG. 2 correspond to the same reference numerals in FIG.

[Brief description of drawings]

FIG. 1 is a cross-sectional view of a main part of a liquid crystal display element according to a first embodiment.

FIG. 2 is a sectional view of an essential part of a liquid crystal display element according to a second embodiment.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 1st glass substrate 2 Pixel switch element 3 Pixel electrode 4 Electrode pad part 6 Light-shielding film 8 2nd glass substrate 9 Color filter 12 Polymer dispersion type liquid crystal layer

Claims (3)

[Claims] 1. A liquid crystal formed by sandwiching a polymer dispersed liquid crystal layer between a first glass substrate on which a pixel electrode and a pixel switch element are formed and a second glass substrate on which a color filter is formed. In the display element, a light-shielding film is formed on one surface of the first glass substrate except a region corresponding to the pixel electrode. 2. The liquid crystal display element according to claim 1, wherein the light shielding film is formed in a region corresponding to an electrode pad portion formed on an outer peripheral portion of the first glass substrate. 3. The liquid crystal display element according to claim 2, wherein the light shielding film is a light reflecting film.