JPH04116525A - Liquid crystal display element - Google Patents

Abstract

PURPOSE:To provide the liquid crystal display element which executes driving at >=1/400 duty even if ITO, In2O3, etc., having a relatively high surface resistance value are used as an electrode material by using a metal having the electric conductivity higher than the electric conductivity of transparent conductive films as an auxiliary electrode material. CONSTITUTION:Auxiliary electrodes 2 are provided in the gap parts between stripe electrodes 1. The auxiliary electrodes 2 and the stripe electrodes 1 are connected by connecting electrodes 3. The auxiliary electrodes 2 and the connecting electrodes 3 have a saw tooth-shaped structure and the parts in contact with the saw teeth are the connecting electrodes 3. The stripe electrodes 1 are formed of the transparent conductive films consisting of the ITO, In2O3, etc. The auxiliary electrodes 2 and the connecting electrodes 3 are formed of metallic films consisting of Au, Ag, Al, Ni, Cr, etc., having the resistance value smaller than the resistance value of the transparent conductive films. The connecting electrodes 3 are provided at the intervals corresponding to one picture element pitch in the positions corresponding to the gaps between the picture elements. The use of the transparent conductive films which have the relatively large surface resistance value and are heretofore inadequate for large-capacity display for 1/400 duty driving, etc., is possible in this way.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to a simple matrix drive type liquid crystal display element, and particularly relates to an improvement in the display electrode structure.

[Conventional technology]

Generally, ITO5In20. In order to time-divisionally drive a liquid crystal display device using a polymer film substrate or a glass substrate provided with a transparent conductive film such as 1/400 duty or more, the surface resistance value of the transparent conductive film must be 20Ω/ (especially when a polymer film substrate is used).

Conventionally, in order to achieve this surface resistance value, improvements such as thinning the transparent conductive film at a relatively high temperature (200 to 250 degrees Celsius) or increasing the thickness of the transparent conductive film (2000 to 4000 degrees Celsius) have been made. By doing so, we achieved a surface resistance value of approximately 20Ω/mouth.

[Problem to be solved by the invention]

However, the above conventional technology has the following problems.

In order to achieve the above surface resistance value, when the substrate is made of a polymer film, it is necessary to form a transparent conductive film at a film formation temperature of 150° C. or lower, which does not cause thermal deformation or alteration of the substrate. be. Also, using such a substrate, 5TN (
When creating a Super Twisted Nematic (Super Twisted Nematic) type liquid crystal display element, if the difference in the interval between the pixel part and the non-pixel part exceeds about 0.25 pIa among the intervals between the segment and common open substrates, the pixel part and the non-pixel part The color difference between the two parts becomes significant, and the quality of the display element deteriorates. For these reasons, it is difficult to reduce the resistance of a transparent conductive film on a polymer film substrate by a commonly used method. Further, even when creating a liquid crystal display element using a glass substrate, problems in display quality remain. On the other hand, as shown in Japanese Unexamined Patent Publication No. 63-65063, a method has also been proposed in which a metal auxiliary electrode made of Au, Al, Cu, Ni, etc. is provided on the top or bottom of a transparent conductive film, but in this case, Since a part of the pixel is shielded from light by the auxiliary electrode, there is a drawback that the aperture ratio of the pixel is reduced.

The present invention solves the problems of the prior art as described above, and has a relatively large surface resistance value (30 to 50 Ω/hole).
It is an object of the present invention to provide a liquid crystal display element that can use a transparent conductive film that is not suitable for large-capacity display such as 400 duty drive.

[Means to solve the problem]

In order to achieve the above object, the present invention includes a segment substrate provided with a plurality of signal electrodes made of striped transparent conductive films arranged in parallel; A simple matrix consisting of a common substrate having a plurality of signal electrodes made of striped transparent conductive films arranged in parallel at right angles to each other, and a liquid crystal sandwiched between the segment substrate and the common substrate. In the driving type liquid crystal display element, an auxiliary electrode made of a metal film having a resistance value smaller than that of the transparent conductive film is provided in the gap between adjacent signal electrodes and between adjacent common electrodes along these electrodes. , characterized in that a connection electrode connected to the signal electrode and a connection electrode connected to the common electrode are provided at positions corresponding to the inter-pixel gap between the signal electrode and the common electrode at intervals corresponding to one pixel pitch from the auxiliary electrode. A liquid crystal display element is provided.

[Effect]

According to the present invention, the film thickness is 200 mm, which can be formed at low temperature.
A transparent conductive film (ITO) with a relatively high surface resistance value of 0 Å or less
, In, O, etc.: Surface resistance value 3O-4 at a film thickness of 1000
Even if the transparent conductive film is patterned into a striped electrode, an auxiliary electrode pass line is provided in the gap between adjacent electrodes, and the non-pixel part of the striped electrode ( By connecting the auxiliary pass line and the striped electrode via the connection electrode to the part that is always off when the liquid crystal display element is configured, the resistance of the electrode structure can be lowered, and the non-pixel part can be Since a portion of the light can be blocked by the auxiliary and connection electrodes, it is possible to provide a function similar to a black mask seen with a color filter, etc., and it is possible to improve the apparent aperture ratio. In addition, by adopting a double redundant structure of auxiliary electrodes and striped electrodes, even if one of them becomes *i, the remaining one becomes a bypass path, making it possible to apply voltage to the electrodes after the disconnection. This also helps prevent defects. Therefore, the above problem is solved.

〔Example〕

The present invention relates to a liquid crystal display element using a simple matrix driving method, which is composed of a segment substrate having signal electrodes, a common substrate having a common electrode, and a liquid crystal sandwiched between these open substrates. Since the feature lies in the electrode structure, the following explanation will focus on the electrode structure.

Transparent conductive film (transparent electrode) such as ITO1In203 on a polymer film such as uniaxially stretched polyethylene terephthalate
When formed to a thickness of about 100λ using vacuum evaporation, plasma evaporation, DC sputtering, ion blating, RF sputtering, etc., these transparent conductive films have a resistance of 40 to 75 Ω/
Indicates the surface resistance value of the mouth. However, with this surface resistance value, 1
Only a simple matrix drive of about /200 duty can be performed. As mentioned above, in order to perform 1/400 duty drive, the surface resistance value of the transparent conductive film needs to be 20 Ω/port or less, preferably 1007 ports or less. Therefore, in the liquid crystal display element of this example, the following electrode structure was adopted.

That is, as shown in FIG. 1(b), an auxiliary electrode 2 is provided in the gap between the stripe electrodes 1.1, and the auxiliary electrode 2 and the stripe electrode 1 are connected by a connection electrode 3.

FIG. 1(a) shows the electrode state before the auxiliary electrode 2 is provided. The auxiliary electrode 2 and the connection electrode 3 have a sawtooth structure as shown in the figure, and the portion corresponding to the sawtooth becomes the connection electrode 3.

The stripe electrode 1 is formed of a transparent conductive film such as the above-mentioned ITO1In203, and the auxiliary electrode 2 and the connection electrode 3 are made of Au, Ag, Al, etc. whose resistance value is lower than that of the transparent conductive film.
It is formed of a metal film such as Ni or Cr. The auxiliary electrode 2 and the connection electrode 3 can be integrally formed at the same time as described below. The connection electrodes 3 are provided at positions corresponding to gaps between pixels (non-pixel portions) at intervals corresponding to one pixel pitch. FIG. 2 shows an enlarged view of a segment substrate having such an electrode structure and a common substrate stacked one on top of the other.

In the figure, 5 is a common auxiliary electrode, 6 is a common stripe electrode,
7 is a segment stripe electrode, 8 is a segment auxiliary electrode, 9 is one pixel, and the broken line indicates the common electrode and the auxiliary electrode attached thereto. In the figure, dimensions in a production example described later are also shown.

Here, an example of a method for creating the electrode structure as described above is shown. First, an ITO film (surface resistance value 40Ω) is deposited on an axially stretched polyethylene terephthalate film by DC sputtering.
/mouth) to a film thickness of 1000 people. Then this IT
The O film is patterned into a striped electrode shape by photolithography and etching using a solution of 12N-HCI:ferric chloride=1:1. After this, A
A thin film with a thickness of 1,000 mm was formed on the entire surface by EB evaporation (sputtering or vacuum evaporation may also be used), and then a second layer was formed by photolithography and etching (4% HCI was used as the etching solution). It is patterned as shown in FIG. 1(b) and used as an auxiliary electrode and a connection electrode. At this time, since the etching solution is diluted HCI, there is almost no erosion of the ITO.

Further, when Au is used instead of A1, a beam lift-off method can be used. In the manner described above, the segment substrate provided with the signal electrode and the common substrate provided with the common electrode according to this embodiment are obtained.

By adopting the electrode structure in which the auxiliary electrode is attached to the stripe electrode as described above, the resistance value of this electrode becomes 10 Ω/hole or less in terms of surface resistance. Furthermore, as shown in Figure 3, even when a disconnection defect is found in the stripe electrode, the auxiliary electrode, or both, the current flows to the next pixel unit using the normal electrode as a bypass path.
Disconnection defects that would cause non-lighting with a single stripe electrode are also less likely to occur in the electrode structure according to this embodiment (in the figure, 10 indicates the auxiliary electrode disconnection, 11 indicates the stripe electrode disconnection, and the arrow indicates the current direction).

〔Effect of the invention〕

According to the present invention, since a metal having higher conductivity than the transparent conductive film is used as the auxiliary electrode material, ITO1In20. Even if used as an electrode material,
It becomes possible to realize a liquid crystal display element that can be driven at 1/400 duty or more. Also.

Since the auxiliary electrode is provided in the gap between adjacent transparent conductive electrodes, it also has a black mask-like function (seen in color filters, etc.) that improves the apparent aperture ratio without degrading display quality. become. Furthermore, since the auxiliary electrode and the transparent conductive film electrode have independent structures to some extent, even if a disconnection defect occurs in one or both, one becomes a bypass, and the electrodes after the disconnection become functional. Has repair ability. 4. Brief description of the drawings FIG. 1(a) is a plan view showing the electrode state before auxiliary electrodes are provided, and FIG. 1(b) shows the electrode structure of a liquid crystal display element according to an embodiment of the present invention. A plan view, FIG. 2 is an enlarged plan view showing a state in which a segment board and a common board with the electrode structure shown in FIG. It is a diagram.

1... Stripe electrode 2...Auxiliary electrode 3...Connection electrode

Claims (1)

[Claims] (1) A segment substrate including a plurality of signal electrodes made of transparent conductive films arranged in parallel stripes, and a striped substrate arranged opposite to the segment substrate and arranged in parallel so as to be orthogonal to the signal electrodes. In a liquid crystal display element of a simple matrix drive system, which is composed of a common substrate having a plurality of signal electrodes made of a transparent conductive film, and a liquid crystal sandwiched between the segment substrate and the common substrate, adjacent signal electrodes Auxiliary electrodes made of a metal film having a resistance value lower than that of the transparent conductive film are provided along these electrodes in the gaps between the electrodes and between adjacent common electrodes, and at intervals corresponding to one pixel pitch from the auxiliary electrodes. A liquid crystal display element characterized in that a connection electrode connected to the signal electrode and a connection electrode connected to the common electrode are provided at positions corresponding to the inter-pixel gap between the signal electrode and the common electrode.