JPH086005A - Liquid crystal display device and its production method - Google Patents

Abstract

PURPOSE:To prevent alignment marks from being damaged even if external force is applied thereon in a rubbing treatment stage, etc. CONSTITUTION:The alignment marks 6 are formed of the same material as a pigment black which is the material of a black matrix 2 simultaneously with formation of the black matrix 2. The alignment marks 6 are coated with protective films 7 which are formed simultaneously with formation of transparent electrodes 4 and consist of the same material as the material of the transparent electrodes 4.

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 a method for manufacturing the same.

[0002]

2. Description of the Related Art In a liquid crystal display device, a black matrix (lattice-like light-shielding portion) is provided on one surface of a transparent substrate made of glass or the like for preventing light from leaking from portions other than the pixel portion. Some have alignment marks for alignment. FIG. 2 shows a part of such a conventional liquid crystal display device. A black matrix 2 as a light-shielding film is provided in the central display area of the upper surface (actually an inner surface for sealing liquid crystal) of a transparent substrate 1 made of glass or the like, and a color filter 3 is provided thereon. Is provided, a transparent electrode 4 made of ITO is provided thereon, and an alignment film 5 is provided thereon. In addition, a predetermined area other than the display area on the upper surface of the transparent substrate 1
An alignment mark 6 is provided at each position.

By the way, in the past, the black matrix 2 was formed of chromium, but recently, in order to reduce the cost, it has been attempted to form it by a pigment black in which carbon is mixed in a resin. There is. In this case, if the alignment marks 6 are simultaneously formed of the same material as the black matrix 2, it is possible to avoid an increase in the number of manufacturing steps.

[0004]

However, if the black matrix 2 and the alignment mark 6 are formed of pigment black, there is no problem in the case of the black matrix 2 covered with the color filter 3, the transparent electrode 4, etc. It was found that the exposed alignment mark 6 has the following problems.
That is, in the case of the pigment black film, the hardness is considerably low and the adhesion is poor as compared with the chromium film. On the other hand, in the manufacturing process of the liquid crystal display device, when the transparent film 4 is formed by patterning the ITO film, the alignment film 5 is subjected to a rubbing process, or when the cleaning is performed after the rubbing process, some kind of transparent film is left on the transparent substrate 1. The stress acts, and in the case of the bare alignment mark 6, it may be considerably damaged, and the alignment mark 6 may be scraped and lost or peeled off.
As a result, the function of the alignment mark 6 is impaired. Further, when the alignment mark 6 is scraped during the rubbing process, there is also a problem that powder generated thereby adheres to the rubbing cloth and the rubbing cloth is contaminated. An object of the present invention is to provide a liquid crystal display device and a manufacturing method thereof in which alignment marks are not damaged during the manufacturing process.

[0005]

According to the present invention, an alignment mark formed of the same material as the light shielding film is covered with a protective film made of the same material as the transparent electrode.

[0006]

According to the present invention, the presence of the protective film can prevent the alignment mark from being damaged even when various stresses are applied. In this case, since the protective film is made of the same transparent material as the transparent electrode, the original position display function of the alignment mark is not impaired. When the transparent electrode and the protective film are formed at the same time as in the third aspect of the invention, the number of manufacturing steps can be increased.

[0007]

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 shows the essential parts of a liquid crystal display device according to an embodiment of the present invention. In this figure,
The same parts as those of the above are denoted by the same reference numerals, and the description thereof will be appropriately omitted. In this liquid crystal display device, the black matrix 2
The structure is such that the alignment mark 6 formed of the same material as that of the pigment black, which is the above material, is covered with the protective film 7 formed of the same material as the transparent electrode 4.

Next, a method of manufacturing a part of this liquid crystal display device will be described. First, the black matrix 2 is formed of pigment black in the central display area of the upper surface (actually the back surface) of the transparent substrate 1 and, at the same time, the alignment marks 6 are formed at two predetermined locations outside the display area with the same material. To form. The forming method in this case may be a photolithography method, but if it is a screen printing method or a relief printing method, it can be formed easily and at low cost. Next, the color filter 3 is formed in the display area by a known method. Next, after forming an ITO film on the entire upper surface of the color filter 3 and removing the unnecessary part of the ITO film by a photolithography method, the transparent electrode 4 is formed at the same time as the display region, and at the same time,
The alignment mark 6 is covered with a protective film 7 made of the same material as the transparent electrode 4. Next, the alignment film 5 is formed in the display area, and a predetermined rubbing process is performed.

In the liquid crystal display device thus obtained, mechanical stress acts on the alignment mark 6 portion during rubbing and cleaning, but the presence of the protective film 7 protects the alignment mark 6 and the stress on the alignment mark 6 is prevented. You can prevent it from being damaged by. In this case, since the protective film 7 is made of the same transparent material as the transparent electrode 4, it does not impair the original position display function of the alignment mark 6. Therefore, the original position display function of the alignment mark 6 is fully exerted, and the alignment of the upper and lower substrates can always be performed accurately. Moreover, since the alignment mark 6 is not scraped during the rubbing process, the rubbing cloth is not contaminated. Furthermore, since the transparent electrode 4 and the protective film 7 are formed at the same time, it is not necessary to increase the number of manufacturing steps.

[0010]

As described above, according to the present invention, due to the presence of the protective film made of the same material as the transparent electrode, the alignment mark is reliably damaged without impairing the original position display function of the alignment mark. Therefore, the original position display function of the alignment mark is fully exerted, and the alignment of the upper and lower substrates can always be performed accurately. Moreover, since the alignment mark is not scraped during the rubbing process, the rubbing cloth is not contaminated. Further, according to the method of the present invention, since the transparent electrode and the protective film are formed at the same time, it is possible to manufacture the liquid crystal display device with high accuracy and at low cost without increasing the number of manufacturing steps.

[Brief description of drawings]

FIG. 1 is a sectional view showing a main part of a liquid crystal display device according to an embodiment of the present invention.

FIG. 2 is a sectional view showing a part of a conventional liquid crystal display device.

[Explanation of symbols]

 1 transparent substrate 2 black matrix (light-shielding film) 4 transparent electrode 6 alignment mark 7 protective film

Claims (3)

[Claims] 1. A light-shielding film provided in a display area on one surface of a transparent substrate, a transparent electrode provided in the display area on one surface of the transparent substrate, and a portion other than the display area on one surface of the transparent substrate. An alignment mark made of the same material as that of the light-shielding film, and a protective film made of the same material as the transparent electrode so as to cover the alignment mark. Display device. 2. The liquid crystal display device according to claim 1, wherein the light shielding film is made of pigment black. 3. A liquid crystal display characterized in that, when manufacturing the liquid crystal display device according to claim 1, the light shielding film and the alignment mark are simultaneously formed, and the transparent electrode and the protective film are simultaneously formed. Device manufacturing method.