JPH10213804A - Production of liquid crystal display device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a manufacturing method of a liquid crystal display device by which the liquid crystal display device with spacers arranged outside pixels can be simply and surely obtained. SOLUTION: The manufacturing method of the liquid crystal display device has a process in which spacers 4 (e.g. 'Micropearl SP (R)' manufactured by Sekisui Fine Chemical Inc., 6.0μm grain size) are charged and dispersed on a substrate 1 (e.g. glass substrate, 50mm square × 1.1mm thickness) on which a metallic light shielding film 2 (e.g. Cr light shielding film) is provided and, then, the spacers 4 on parts except the metallic light shielding film 2 are removed by air blowing while applying voltage to the metallic light shielding film 2 with polarity reverse to that of the spacers 4.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a method for manufacturing a liquid crystal display, and more particularly to a method for manufacturing a liquid crystal display having excellent display characteristics.

[0002]

2. Description of the Related Art In general, in a liquid crystal display device, liquid crystal is interposed between a pair of electrode substrates on which an alignment film is formed, and a plurality of spacers are sandwiched for the purpose of controlling the interval between these electrode substrates. As a material of such a spacer, a resin, glass, or the like is used. 2. Description of the Related Art In a liquid crystal display device, display is performed by controlling the orientation of liquid crystal by turning on and off a voltage and changing the state of light transmission. At this time, since the transmittance of the spacer portion is not related to the application of the voltage, the presence of the spacer on the pixel causes a display defect or lowers the contrast. Therefore, a method for removing the spacer from the pixel is proposed in Japanese Patent Application Laid-Open No. 4-42126.

According to the method disclosed in the above publication, a large number of pixel components composed of pixel electrodes and thin film transistors are arranged in a matrix, and a plurality of row selection lines and column selection lines connecting the thin film transistors are formed. A liquid crystal layer is provided between the one substrate and the other substrate facing each other via a spacer scattered on the one substrate. A first terminal to which the plurality of row selection lines are collectively connected, and a second terminal to which the plurality of column selection lines are collectively connected, wherein the first terminal And alternately connecting the second terminals to a positive potential and a ground potential and a ground potential and a positive potential, respectively, at a speed slower than the operation speed of the thin film transistor to connect the plurality of row selection lines and The negatively charged spacers are sprayed on the one substrate while alternately charging the column selection lines positively, so that the plurality of positively charged row selection lines and column selection lines are negatively charged. A method for manufacturing a liquid crystal display element, wherein the spacer is mounted.

[0004]

However, according to the method disclosed in the above publication, the operation of attracting the spacer on the row selection line or the column selection line by the electric attraction is performed during the dispersion of the spacer, so that the effect is weak and uncertain. There is a problem that the contrast cannot be significantly improved because the remaining of the spacer in the pixel portion cannot be completely prevented. An object of the present invention is to provide a method for manufacturing a liquid crystal display device that can more easily and reliably obtain a liquid crystal display device in which spacers are arranged outside pixels.

[0005]

According to a method of manufacturing a liquid crystal display device of the present invention, a spacer is charged and dispersed on a substrate provided with a metal light-shielding film, and then a voltage is applied to the metal light-shielding film in a polarity opposite to that of the spacer. The method is characterized in that the method includes a step of removing the spacers other than the metal light-shielding film by air blowing while applying the voltage.

The shape and material of the spacer used in the present invention can be any known ones and are not particularly limited. In general, the following are mentioned. That is, examples of the shape include a fiber shape and a true sphere (bead) shape, but a true sphere is preferable. As a material, for example,
Examples thereof include inorganic materials such as glass and organic materials such as resins. Examples of resins include styrene / divinylbenzene copolymers and benzoguanamine / melamine / formaldehyde condensates. The diameter of the spacer is generally 3 to 15
μm is preferred.

Hereinafter, an example of a method for manufacturing a liquid crystal display device of the present invention will be described according to a procedure.

(1) First, a spacer is charged and dispersed on a substrate provided with a metal light shielding film. Examples of a method for charging the spacer include corona discharge, charging by friction, and electron beam irradiation. A method using corona discharge is preferable. As a method for measuring the charge amount of the spacer, a blow-off method is generally used. The blow-off method is a method in which charged particles are hit against a wire net and the charged amount of the particles is calculated from the charged amount of a capacitor connected to the wire net. The specific method is described in Koguchi et al., Electrophotography, No. 16
Vol. 2, No. 52, 1977.

As the substrate, for example, a glass substrate can be used. Examples of the metal light-shielding film include a chrome light-shielding film. In order to manufacture a substrate provided with a metal light-shielding film used in the present invention, a metal for forming a light-shielding film is formed on the substrate by sputtering or the like, and overcoated (for example, with a polyimide resin), IT
A method of sequentially laminating an O electrode (formed by sputtering or the like) and an alignment film (for example, of a polyimide resin) and performing rubbing is used.

As a method of spraying the spacer in the present invention, a general dry spraying method is preferable, and the spraying is performed on the substrate on which the metal light shielding film is formed.

(2) Next, while applying a voltage to the metal light-shielding film in a polarity opposite to that of the spacer, the spacers other than the metal light-shielding film are removed by air blow.

In the method of applying a voltage to the metal light-shielding film, the charging characteristic of the spacer is measured in advance, and a voltage having a polarity opposite to that is applied. The applied voltage varies with the strength of the adhesion between the spacer and the alignment film.
000V is preferable, and 300-1000V is more preferable.

When the strength of the air blow becomes weak, it becomes difficult to remove the spacer from portions other than the metal light shielding film.
Because it can be too strong rides on the metal light-shielding film spacer is removed, preferably ^{0.1~10kgf / cm 2, 1~5kgf / cm} 2 is more preferable.

(3) Next, a known sealant (for example, an epoxy adhesive) is placed around the obtained substrate from which the spacers other than the metal light-shielding film have been removed by a method such as screen printing. After another substrate is superimposed on the substrate, a load is applied by a press machine so as to uniformly apply the entire substrate, and at the same time, the sealant is cured.

(4) Next, a liquid crystal material is injected through a hole provided in a part of the sealant by a known method to obtain a liquid crystal display device. The liquid crystal material is not particularly limited as long as it is a nematic liquid crystal having a positive dielectric anisotropy.

[0016]

Embodiments of the present invention will be described below.
You. (Example) Spacer (Miku, manufactured by Sekisui Fine Chemical Co., Ltd.)
Lopar SP, particle size 6.0 μm) negatively corona-discharged
To form a Cr light-shielding film (sputtering film formation, film thickness
0.1 μm) and overcoated (Chisso Corporation,
PSI-G-4630 (polyimide)], ITO electrode
(Sputter deposition, 100Ω / □), alignment film [Nissan
Chemical company, SE-150 (polyimide), thickness 0.1
μm] are sequentially laminated and rubbed (glass-based
Plate, 50 mm square x 1.1 mm thickness).
Spray density 200 pieces / mm^TwoAnd Space at this time
When the charge amount of the solar cell was separately measured by a blow-off method,
It was 5.1 μC / g. Next, +12 is applied to the Cr light shielding film.
3 kg with an air gun while applying a DC voltage of 00 V
f / cm ^TwoAir blow with the strength of
He blew away the server.

FIG. 1 schematically shows the state of the spacer spraying step and the air blowing step. In FIG. 1, for simplification, a substrate 1, a metal light shielding film 2, and an alignment film 3 are shown.
And only the spacers 4 are shown.

Next, a 240 ° twisted STN cell of a simple matrix was fabricated using this substrate. As a liquid crystal, a liquid crystal ZLI2293 for STN + chiral agent S811 manufactured by Merck & Co. was used, and as a sealant, a struct bond (epoxy type) manufactured by Mitsui Toatsu Co., Ltd. was used.

Next, when the liquid crystal display device thus manufactured was observed with a polarizing microscope, the number of spacers existing in the pixel was 2.3% of the whole (see FIG. 2). When the luminance Y in the dark field was measured by a color difference meter, it was as good as 72% of the comparative example described later, and this liquid crystal display device was excellent in contrast without display defects.

(Comparative Example) A spacer (Micropearl SP, manufactured by Sekisui Fine Chemical Co., Ltd., particle size: 6.0 μm) was applied on the same substrate as in Example by a usual method (no spacer charging by corona discharge, Cr light shielding film). (No voltage applied, no air blow). Using this substrate, a simple matrix STN cell was prepared in the same manner as in the example, and observed with a polarizing microscope. As a result, the number of spacers present in the pixel was 68% of the whole (see FIG. 3). The luminance Y in the dark field was about 1.4 times that of the example, display defects were conspicuous, and the contrast was inferior.

[0021]

The structure of the method for manufacturing a liquid crystal display device according to the present invention is as described above. When this manufacturing method is used, spacers are scattered on a substrate provided with a metal light-shielding film, and then the spacer is applied to the metal light-shielding film. A voltage is applied in the opposite polarity to the spacer, and air blow is performed while attracting the spacer of the metal light-shielding film by an electric attraction, so that the spacer of the portion other than the light-shielding film is eliminated, so that the spacer is disposed outside the pixel. As a result, a liquid crystal display device having no display defects and having excellent contrast can be obtained more easily and reliably.

[Brief description of the drawings]

FIG. 1 schematically shows a state of a spacer spraying step and an air blowing step.

FIG. 2 is a schematic diagram showing a result of observing a liquid crystal display device obtained in an example with a polarizing microscope.

FIG. 3 is a schematic diagram showing a result of observing a liquid crystal display device obtained in a comparative example with a polarizing microscope.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Substrate 2 Metal light shielding film 3 Alignment film 4 Spacer

Claims (1)

[Claims] 1. A method in which a spacer is charged and dispersed on a substrate provided with a metal light-shielding film. Then, while applying a voltage to the metal light-shielding film in a polarity opposite to that of the spacer, air blow is applied to portions other than the metal light-shielding film. A method for manufacturing a liquid crystal display device, comprising a step of removing a spacer.