JPH0237325A - Liquid crystal display element - Google Patents

Abstract

PURPOSE:To obtain the liquid crystal display element which has good reliability in a sealing part and has less unequal images by adopting an urethane resin or polyimide to the sealing part and, for example, an acrylic resin to the other parts, for example, picture element parts, as the material for protective layers of color filters. CONSTITUTION:The protective layer 9 as the top coat of the color filters 8 is formed of a 1st protective layer 9a consisting of the urethane resin in the sealing part where a sealing material exists and the 2nd protective layer 9b consisting of the acrylic resin in the parts exclusive of said part. The material of the protective layer 9 for the color filters is discriminated to the sealing part and the other part by noticing the characteristics of the resins that the acrylic resin is higher in hardness than the urethane resin or polyimide and conversely that the urethane resin or polyimide has the higher adhesive strength to the sealant than the acrylic resin. A uniform gap is obtd. with high accuracy in this way and the improvement in the sealing strength is attained. Both of the image arising from the unequal gap and the degradation in the reliability arising from the deterioration of the sealing part are prevented.

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention 1 (Field of Industrial Application) This invention relates to a liquid crystal display element having a color filter.

(Prior Art) In recent years, thin film transistors made of polysilicon, amorphous silicon (a-8i), tellurium, etc.
ansistor, T F T >, or MIM
(Metal-Insulator-)1etal)
BACKGROUND ART Active matrix liquid crystal display elements using nonlinear elements such as MOS elements as switching elements have come to be widely used in TV displays and the like.

An example of this type of liquid crystal display element is that a TPT is provided on one substrate at each intersection of matrix wiring consisting of a group of signal lines and a group of scanning lines, and its source electrode or One of the drain electrodes is connected to the pixel electrode.

In addition, on the other substrate, for example, red, green, and blue color filters are arranged in areas corresponding to the pixel electrodes, and the remaining grid-like area is covered with a light-shielding film as a black matrix. A counter electrode is formed. A liquid crystal is sandwiched between these two substrates, and a polarizing plate is provided on the outer surface of each of the two substrates.

By the way, in this type of liquid crystal display element, in order to prevent image unevenness, it is necessary to bond two substrates together using a plastic spacer or the like while maintaining a highly precise and uniform gap. Here, since the spacer may damage the red, green, and blue dyeing layers of the color filter, a protective layer of acrylic resin or urethane resin with a thickness of about 0.5 to 2.0 μm called a top coat is used. is further formed on the color filter.

(Problems to be solved by the invention) Among these, regarding the protective layer made of acrylic resin,
Since the adhesion force with the sealant is weak, the strength of the seal part is low and there is a problem with reliability, and in the worst case, there is a risk that the seal will peel off or bubbles may enter. In addition, with regard to the protective layer made of urethane resin, the material is soft, so the spacer sinks in easily and is easily affected by uneven sealing loads during bonding, making it difficult to form gaps with high precision. This was difficult, and image unevenness defects were likely to occur.

This invention was made in view of such conventional circumstances.

[Structure of the Invention] (Means for Solving the Problems) This invention combines two substrates with their peripheral seals so that their surfaces face each other, and sandwiches a space length and a liquid crystal in this gap. This refers to a liquid crystal display element that can display colors through the action of a color filter, and the protective layer for the color filter is made of urethane resin or polyimide for the sealing part, and acrylic for other parts, such as the pixel part. It uses resin.

(Function) This invention is based on the characteristics that acrylic resin has higher hardness than urethane resin or polyimide, and conversely, urethane resin or polyimide has stronger adhesion to the beseal agent than acrylic resin. Focusing on this, the material of the protective layer for color filters is differentiated between the seal part and other parts.

Regarding the above-mentioned characteristics, for example, Fig. 2 shows the indentation load and JIS of acrylic or urethane resin.
(Japan Industrial 5tanda
rd ) is a diagram showing the relationship between Knoop hardness defined by . In the figure, the solid line connecting white circles represents the characteristics of acrylic resin, the solid line connecting black circles represents the characteristics of urethane resin, and the dotted line represents the characteristics of the underlying dye layer (color filter). It shows the characteristics. As can be seen from the figure, acrylic resin has higher hardness than urethane resin and dyed layer. In addition, Figure 3 is a bird's-eye view showing the deviation from a 6 μm cell gap in a liquid crystal display element using urethane resin ((a) in the same figure) or acrylic resin ((b) in the same figure) as the top coat of the color filter. As can be seen from the figure, when acrylic resin is used, the gap variation is smaller than when urethane resin is used.

Then, we fabricated 10 liquid crystal display elements each using acrylic resin or urethane resin as the top coat of the color filter, and conducted a pressure test at 2 atm and 120°C for 5 hours. As a result, we found that the seal portion deteriorated. The number of liquid crystal display elements in which this was observed was as many as six in the case of liquid crystal display elements using acrylic resin, but only one in the case of liquid crystal display elements using urethane resin.

Up until now, we have only talked about urethane resins, but
Polyimide, which is an alternative to this, also has properties similar to those of urethane resins in relation to acrylic resins.

(Example> The details of this invention will be explained below with reference to the drawings.

FIG. 1 is a sectional view showing an embodiment of the present invention. In the figure, on one main surface 1a of a substrate 1 made of, for example, glass, there are a plurality of TPTs as active elements 2 and a pixel electrode 3 made of, for example, ITO (indium tin oxide) connected thereto. Further, around the pixel electrode 3, a matrix-like wiring 4 consisting of a gate line and a signal line is formed. An alignment film 5 made of polyimide, for example, is formed to cover the active elements 2 and wiring 4. On the other hand, a light-shielding film 7 made of, for example, Cr (chromium) and having predetermined openings is formed on the whole surface 6a of the substrate 6, which is also made of glass, for example, and further, a light-shielding film 7 made of, for example, Cr (chromium) is formed for each of the above-mentioned openings. A predetermined color filter 8 is formed by, for example, a dyeing method. A protective layer 9 is formed to cover the light shielding film 7 and the color filter 8, and a common electrode 10 made of ITO, for example, and an alignment film 11 made of polyimide, for example, are successively formed thereon. Here, the protective layer 9 is divided into two parts, and the part that will later become a seal part is a first protective layer 9a made of urethane resin, such as Dainippon Printing 1 wood, and the other parts are made of acrylic resin. For example, JSS (
The second protective layer 9b is made of Nippon Synthetic Rubber Co., Ltd.). Then, the two substrates 1゜6 are placed on each other's main surfaces 1a and 6a.
They are assembled using a peripheral sealant 12 so that their sides face each other, and a spacer 13 and a liquid crystal 14 are sandwiched in this gap. Furthermore, polarizing plates 15 and 16 are attached to the other main surfaces 1b and 6b of the substrates 1 and 6, respectively.
, 6 is illuminated from the other main surface 1b, 6b side.

In this embodiment, the protective layer 9 as a top coat of the color filter 8 includes a first protective layer ff1s9a made of urethane resin in the sealing part where the sealing agent 12 is present, and a second protective layer 9 made of acrylic resin in the other parts. This is the protective layer 9b. As a result, compared to the conventional case where the protective layer 9 is made of either urethane resin or acrylic resin, a highly accurate and uniform gap can be obtained, and the sealing strength is improved. It is possible to prevent both image defects caused by unevenness and decreased reliability due to deterioration of the seal portion.

Although the case where the first protective layer 9a is made of urethane resin has been described so far, the same effect can be obtained even if the first protective layer 9a is made of polyimide.

[Effects of the Invention] By distinguishing the top coat of the color filter between the seal portion and other portions, it is possible to obtain a liquid crystal display element with good reliability in opening the seal portion and with less image unevenness.

[Brief explanation of the drawing]

Figure 1 is a cross-sectional view showing one embodiment of the present invention, Figure 2 is a diagram showing the relationship between indentation load and Knoop hardness in acrylic or urethane resin, and Figure 3 is a cross-sectional view showing an embodiment of the invention. It shows the deviation from the specified cell cap for the liquid crystal display element that was used! It is an inkstone drawing. 1.6...Plate la, 6a...-Main surface 8...Color filter 9...Protective layer 13...Spacer 14...Liquid crystal agent Patent attorney Ken Ken 1Right Takehana Kikuo Figure 1 Figure Acrylic Figure

Claims (1)

[Claims] Two substrates are combined by a peripheral seal portion so that one main surface side faces each other, and a spacer and a liquid crystal are sandwiched in this gap, and at least one of the two substrates is placed on the one main surface side. 1. A liquid crystal display element comprising a color filter and a protective layer formed in sequence, wherein the protective layer is made of urethane resin or polyimide in the sealing part and acrylic resin in other parts.