JPH03290621A - Liquid crystal display element - Google Patents

Abstract

PURPOSE:To obtain a high-definition LCD where the color unevenness due to the change of retardation is prevented by forming a dummy electrode in an area where the transparent electrode of one electrode substrate is not present thereon. CONSTITUTION:A dummy electrode 8 which has the same thickness as a transparent electrode 6 and is made of the same material ITO as the electrode 6 is formed in the area where the transparent electrode 6 of a lower glass substrate 5 out of a pair of glass substrates 2 and 5 is not present there on. The dummy electrode 8 is electrically isolated and does not have the function as an electrode, and the difference between thickness d2 of the liquid crystal layer in a non-display area and thickness d1 of liquid crystal in a display area B is reduced by the film thickness of a transparent electrode 3 by the presence of the electrode 8. Consequently, color unevenness due to the change of retardation is made inconspicuous to contribute to the improvement of the quality of the S-TN type LCD.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a liquid crystal display element (hereinafter referred to as LCD).
In particular, it relates to a 5-TN type LCD.

[Conventional technology]

FIG. 4 is a sectional view showing the basic structure of a conventional LCD, which includes an electrode substrate 1 formed by patterning a transparent electrode 3 on the lower surface of an upper glass substrate 2, and a transparent electrode 6 on the upper surface of a lower glass substrate 5. A liquid crystal 7 is sealed between the electrode substrate 4 formed by patterning the transparent electrode 3.6, and ITO is generally used as the transparent electrode 3.6.

In recent years, with advances in LCD manufacturing technology, 5-TN type LCDs capable of high-quality display have become popular. In such a 5-TN type LCD, the gap d between the upper and lower glass substrates 2.5 is as small as about 7 μm, and the liquid crystal molecules are continuously twisted by 180 to 270 degrees along the thickness direction (vertical direction in FIG. 4). It has a similar structure.

[Problem to be solved by the invention]

However, in the conventional 5-TN type LCD, the transparent electrode 3
．． The thickness dl of the liquid crystal layer in the display area B where the transparent electrode is formed is smaller by the thickness of the picture electrode 3.6 than the thickness (gap) d of the liquid crystal layer in the non-display area A where 6 does not exist. Therefore, the so-called retardation, the product Δn-d of the refractive index anisotropy Δn of the liquid crystal and the liquid crystal layer thickness d, changes between the non-display area A and the display area B, and this is visually observed as a difference in color tone, that is, color unevenness. There was a position to be held. In particular, in the case of the segment display type, since the area of the non-display area A is relatively large, there is a high possibility that color unevenness will be visually observed, which inevitably leads to a decline in quality.

Therefore, an object of the present invention is to provide a high-quality LCD that prevents color unevenness caused by changes in retardation.

[Means to solve the problem]

An object of the present invention described above is to form an electrically isolated dummy electrode made of the same material and approximately the same thickness as the transparent electrode in an area where the transparent electrode is not present on the transparent electrode forming surface of at least one electrode substrate. achieved by.

[Effect]

By forming a dummy electrode in the non-display area of one or both of the upper and lower electrode substrates, the difference between the thickness of the liquid crystal layer in the non-display area and the thickness of the liquid crystal layer in the display area can be reduced or eliminated. , uneven color becomes less noticeable.

〔Example〕

Embodiments of the present invention will be described below based on the drawings.

FIG. 1 is a cross-sectional view showing the basic configuration of an LCD according to an embodiment of the present invention, and FIG. 2 is a plan view showing the electrode pattern of this LCD, where parts corresponding to those in FIG. It is attached.

The LCD shown in Figure 1.2 is a 5-segment display type.
- In a TN type LCD, the gap d between the upper and lower glass substrates of 2°5 is as small as about 7 μm, and the twist angle of the liquid crystal molecules is 180
It is large at ~270°. In this 5-TN type LCD, a dummy electrode (pseudo electrode) 8 made of ITO and having the same thickness as the transparent electrode 6 is formed on the upper surface side of the lower glass substrate 5 in an area where the transparent electrode 6 is not present. Due to the presence of this dummy electrode 8, the thickness d of the liquid crystal layer in the non-display area A is
2 and the thickness d of the liquid crystal layer in the display area B is the difference between the transparent electrode 3 and the thickness d of the liquid crystal layer in the display area B.
The membrane thickness of the bone is reduced.

It goes without saying that the dummy electrode 8 is electrically isolated and has a function as an electrode, and that the dummy electrode 8 and the transparent electrode 6 can be formed together.

In this way, in the above embodiment, by forming the dummy electrode 8, the thickness d2 of the liquid crystal layer in the non-display area A is brought closer to the thickness d of the liquid crystal layer in the display area B. The change in retardation between display area A and display area B is small, color unevenness is less noticeable, and quality is improved.

In addition, in the above embodiment, the dummy electrode 8 is attached to the electrode substrate 4.
Even if the dummy electrode 8 is formed on the electrode substrate 1 instead of on the electrode substrate 1, that is, even if the dummy electrode 8 is formed on the lower surface side of the upper glass substrate 2, almost the same effect can be expected.

FIG. 3 is a cross-sectional view showing the basic structure of an LCD according to another embodiment of the present invention, showing a region where no transparent electrode 3 is present on the lower surface side of the upper glass substrate 2 and a region on the upper surface side of the lower glass substrate 5. A dummy electrode 8 is provided in each region where the transparent electrode 6 is not present.
are formed and are opposed to each other, so that the thickness of the liquid crystal layer in the non-display area A is d.

is equivalent to the thickness d of the liquid crystal layer in display area B.

Therefore, the retardation does not change between the non-display area A and the display area B, and there is no fear of color unevenness.

In addition, in this embodiment, since the dummy electrodes 8.8 are in a floating state, static electricity may be discharged between these electrodes 8.8 and cause erroneous display. A transparent conductive layer 9 is formed, and this conductive layer 9 is grounded.

〔Effect of the invention〕

As explained above, according to the present invention, a dummy electrode is formed on the transparent electrode forming surface of at least one electrode substrate to reduce the difference between the thickness of the liquid crystal layer in the non-display area and the thickness of the liquid crystal layer in the display area. Or, because it has been resolved, the color unevenness caused by changes in retardation becomes less noticeable, and the 5-TN type L
This greatly contributes to improving the quality of CDs.

[Brief explanation of the drawing]

FIG. 1 is a sectional view showing the basic structure of an LCD according to an embodiment of the present invention, FIG. 2 is a plan view showing an electrode pattern of this LCD, and FIG. 3 is a cross-sectional view of an LCD according to another embodiment of the present invention. FIG. 4 is a sectional view showing the basic structure of a conventional LCD. 1.4... Electrode substrate, 2... Upper glass substrate, 3゜6... Transparent electrode, 5... Lower glass substrate, 7... . . . Liquid crystal, 8 . . . Dummy electrode, 9 . . . Conductive layer.

Claims (2)

[Claims] (1) In a liquid crystal display element in which a liquid crystal is sealed between a pair of upper and lower electrode substrates each having a pattern of transparent electrodes formed on each opposing surface, the transparent electrode is formed on the transparent electrode-forming surface of at least one of the electrode substrates. A liquid crystal display element characterized in that an electrically isolated dummy electrode made of the same material and approximately the same thickness as the transparent electrode is formed in a region where the transparent electrode does not exist. (2) In claim (1), the dummy electrode is formed on each of the pair of upper and lower electrode substrates, and a conductive layer is formed on the upper surface of the upper electrode substrate, and the conductive layer is grounded. LCD display element.