JPH01239527A - Production of liquid crystal display device - Google Patents

Abstract

PURPOSE:To inhibit penetration of light from a light source by shutting out spacers in a picture element zone by forming island-shaped regions comprising a mixture of the spacers and an adhesive material by screen printing after mixing the spacers with the adhesive material. CONSTITUTION:An adhesive material, which may be either a thermosetting resin or an ultraviolet setting resin, is adjusted to have ca. 10cPs viscosity, and stirred sufficiently in a glass vessel together with spacers. A soln. consisting of the spacer and the adhesive material 1 is then applied to above an orientation film 10 formed previously on a substrate provided with a transparent electrode by screen printing, to form thus a specified pattern. Thus, the spacers are fixed to the surface of the orientation film 10 other than picture element areas 13 on the substrate provided with electrode, so penetration of light, etc. is inhibited.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a liquid crystal display device for displaying characters or images, and more particularly to a method for manufacturing a liquid crystal display device having a substrate with electrodes on which spacers are fixed on an alignment film. be.

BACKGROUND OF THE INVENTION Conventional methods for manufacturing liquid crystal display devices include a printing method using a letterpress printing method and a coating method using a spinner or gun spray to form an alignment film. In addition, a spacer interposed between electrode-attached substrates in a liquid crystal display device is made of glass, plastic, or the like, and has a cylindrical or spherical shape. At this time, it is desirable to minimize the amount of alkaline elements in the composition of the glass from the viewpoint of reliability with the liquid crystal, for example, the main component is SiO2, and 20, etc. are included in AI20s, Fe2es, Na2O, etc. A material containing about 0.7 pp- of Na and K is used. In addition, hardened spherical particles containing penzoguanamine formaldehyde condensate (existing chemical substance structure classification reference number 7-31) were used in a plastic smoothing material.

There are generally two methods for dispersing spacers: an in-air method and an in-liquid method. The air method is a method in which the spacers are dispersed together with the airflow within the device, and the discharge airflow is set to about 0.3 kg/ci and 15 liters/min and allowed to fall freely, or conversely, the discharged airflow is set to 4 kg/min. There are some types that force the drop at a rate of about 200 liters/min. The former can be dispersed relatively uniformly, but requires a long time to fall. Although the latter method can relatively shorten the falling time, it requires some ingenuity and may result in a lump of spacer being ejected. The ideas mentioned here include, for example, removing static electricity from the substrate and neutralizing it electrostatically, using the atomizing principle to supply spacers to increase the flow rate and preventing the spacers from clumping, and passing the spacers through a filter to remove any clumping beforehand. And so on. Furthermore, whether the shape is cylindrical or spherical, the fine powder used for the spacer requires countermeasures against static electricity.

As the submerged method, a method of dispersing using a spinner or the like is generally known. If alcohol or acetone is used as the liquid to mix the spacer, it will attack the surface of the alignment film and deteriorate the alignment properties. Therefore, using a chemically stable Freon solution, drop the mixed solution onto the alignment film on the electrode-attached substrate placed on a spinner, and operate the spacer at 100 r, ρ, and 1 for about 3 minutes to remove the spacer. Spread. Further, instead of dropping the solution mixed with spacers, the solution mixed with spacers can be evenly dropped on the surface of the alignment film, and then a spinner can be operated to achieve even more uniform dispersion.

Organic materials such as polyimide and polyvinyl alcohol are used for the alignment film. For example, when printing using letterpress printing,
The ratio of the weight of polyimide to the weight of solvent is about 7.5% wt. After applying the alignment film, a heating furnace is used for curing, and the film is heated in N2 at a temperature ranging from about 170°C to about 350°C for several hours.

FIG. 7 shows a state in which spacers are dispersed after forming an alignment film in this manner. A substrate with an electrode with a color filter and a substrate with an electrode with a TPT element (thin film switching element) are used in liquid crystal display devices such as color LCD televisions.
In the figure, after forming an alignment film on the electrode-attached substrate with the TPT element, the spacers 20 are evenly (not evenly) coated on the TPT element part 21, the wiring part 22, and the pixel part 23 by an air method. It is dispersed.Almost the same results are obtained whether the dispersion method is used in air or in liquid.

As a conventional technique, for example, Japanese Patent Application Laid-Open No. 59-222817
As shown in the publication, it had a structure as shown in Figure 8. A spacer material mixed with a photosensitive resin is applied onto a substrate, and spacers are formed at predetermined locations by a photomask process. Also, the spacer positions are changed to spacers 25, 26 located within the hatched area on the gate line 24 on the substrate, spacers 28, 29, 30 located on the source line 27, or spacers 28, 29, 30 located within the shaded area on the drain electrode 31. Installed at 32.33.34 etc.
Avoid overlapping the thin film transistor part or the cross-over part with multilayer wiring. The structure is such that a spacer material such as a glass fiber is mixed into a photosensitive resin, which is coated on the entire surface by printing or other methods, buttered by a photomask process, developed, and then baked and hardened.

In this way, in the conventional manufacturing method of liquid crystal display devices, glass fibers are mixed in and formed on the gate line and drain electrodes, which are wider than the line width (and may also be formed in the pixel area, resulting in poor image quality). In addition, the alignment treatment was insufficient in areas that protruded outside the line.Furthermore, the photosensitive resin used here was Toshi Co., Ltd.'s [Photonice UR-3100J], and the viscosity was Spacers exist in the photosensitive resin, and pressure is required to remove the photosensitive resin existing between the substrates in order to form a predetermined gap in the liquid crystal display device.The pressure causes the wiring section to etc. Moreover, since the adhesive is thick, it seems that the accuracy of the spacing cannot be expected due to the influence of the clay.

Problems to be Solved by the Invention As described above, it is difficult to selectively form spacers in the conventional spacer manufacturing method for manufacturing liquid crystal display devices, and even if spacers can be selectively formed, it is difficult to perform sufficient alignment treatment. In addition, since there is a spacer in the pixel portion, there is a problem in light extraction from the light source, which significantly deteriorates the image quality.

The present invention has been made in view of these points, and is a liquid crystal display that selectively forms spacers with a simple configuration, provides sufficient alignment processing, eliminates the presence of spacers in one pixel area, and prevents light leakage from the light source. The purpose of this invention is to provide a method for manufacturing a display device.

Means for Solving the Problems In order to solve the above problems, the present invention comprises a set of electrode-equipped substrates, an alignment film formed on the electrode-equipped substrate, and a spacer fixed on the alignment film. Manufacturing a liquid crystal display device consists of a step of mixing spacers and an adhesive, and a step of forming an island-like region in which the spacers and adhesive are mixed by screen printing.

Effect of the present invention By fixing the spacer to the surface of the alignment film other than the pixel area on the substrate with electrodes by the method described above, there is no light leakage (and there is no sagging etc. at the boundary between the surface of the alignment film and the spacer). Since there is no gap, good alignment of the liquid crystal can be obtained, and a predetermined gap inside the liquid crystal display device can be formed with high precision.

EXAMPLE Hereinafter, an example of the present invention will be described based on the drawings. A liquid crystal display device manufactured based on the manufacturing method of the present invention is shown in FIGS. 5 and 6.

In FIG. 5, the liquid crystal display device includes a transparent electrode 9, a front glass plate 11 with an alignment film 10 thereon, and a TPT element (
A liquid crystal display substrate 1 comprising a transistor element (transistor element) section 12 and a pixel section 13 composed of thin film transistors and used for switching the voltage applied to a pixel electrode, and an alignment film 14 thereon.
5, there is a sealing material 16 mixed with a predetermined spacer in the peripheral portion, and a liquid crystal 17 is present in the panel surrounded by the sealing material 16. And polarizing plate 18.19
are attached to both sides of the front glass plate 11 and the liquid crystal display substrate 15.

FIG. 6 shows the structure on the substrate 15 side, where G is TPT.
The gate electrode of the device, ▪ is an insulating film, A is a channel active region made of amorphous silicon, and M is a source/drain electrode.

First, a method for manufacturing the liquid crystal display device of this example will be explained. A printing method was used to form an alignment film made of polyimide on a substrate with electrodes. Screen printing and letterpress printing are generally used as printing methods, and letterpress printing was used in this example.

Using a diluent consisting of NMP (N-methyl-2-pyrrolidinone) and butylcellolove, the polyimide stock solution was diluted to approximately 8%.
A predetermined pattern is printed by letterpress printing and cured in a clean oven at 170°C for 2 hours. Furthermore, it has been confirmed that the cured material can be cured in the same manner at 350° C. for 1 hour. A solution containing a mixture of spacers and adhesive is printed on the alignment film thus formed by screen printing.

An explanation of an embodiment used in the method of manufacturing a liquid crystal display device of the present invention is shown in FIG. 1 below. FIG. 1(a) shows a plan view of a screen plate, and this screen plate has holes 1 of a predetermined shape with high accuracy by etching.

Further, FIG. 1(b) shows a front view of the screen plate, and since metal is preferable as the material for the screen plate 2, stainless steel was used in this embodiment. The shape of the spacer can be a cylinder or a sphere, but a cylinder is not appropriate due to the size of the hole, so a sphere was used. The size of the hole in the screen plate is 30 μm×60 μm. However, the size of the hole may be any size, and if the size of the hole can be made even larger, it would be possible to use a cylindrical spacer. However, in this example, since spheres with a diameter of 6 μm were used, uniform printing could be performed with the above-mentioned hole size. Also, the thickness of the screen plate is approximately 100μ
It is m. However, this thickness may be arbitrary and can be selected depending on the predetermined size of the pattern.

Furthermore, when applying a solution containing a spacer that forms a gap between liquid crystal panels and an adhesive on the above-mentioned alignment film by screen printing, the adhesive may be either a thermosetting resin or an ultraviolet curable resin. In particular, this time we used epoxy resin, a thermosetting resin. Also, its viscosity is about 10 cp
A spacer was added in a glass container, and the mixture was thoroughly stirred. Although the spacer may be spherical or cylindrical, a spherical spacer made of plastic was used in this embodiment. The spacer is provided to regulate the gap between the substrates with transparent electrodes, and has a diameter of about 6 μm. Examples of methods for applying a solution containing a mixture of spacers and an adhesive onto an alignment film previously formed on a substrate with transparent electrodes include printing using a spinner, spray, and roll coater, screen printing, and offset printing. In this example, the coating was particularly performed by screen printing. Screen printing plates are usually made of metal such as stainless steel knitted into a mesh shape and coated with resin, eliminating the resin for a predetermined pattern, but in the screen printing plate of this example, holes were formed by etching a thin sheet metal. It is something.

In the conventional example, when a resin with low viscosity is applied, it wraps around the bottom of the screen plate and forms a shape different from the shape of the predetermined pattern, but in the case of using the screen plate of this example, the resin with low viscosity is applied. also has a shape almost equal to the shape of the predetermined pattern.

The mixing ratio of spacer and adhesive is 1:100. Screen printing was performed in this state to form a predetermined pattern.

The conditions for curing the adhesive formed in a predetermined pattern are 1
2 hours at 50°C.

Since the size of the adhesive is sufficiently thin compared to the size of the spherical spacer, it hardens while the adhesive is present under the spacer. Therefore, the spacer can be fixed on the alignment film.

FIG. 2 shows a state in which the spacer coated on the alignment film on the liquid crystal display substrate is cured with an adhesive.

While the size of the spacer 3 formed on the alignment film is 6 μm, the size of the adhesive 4 made of thermosetting resin is at most 20 μm.
00A, which is sufficiently thin, so that the gap between the substrates in a liquid crystal display device is approximately equal to the size of the spacer. Furthermore, the pattern consisting of the spacer is formed on the wiring part within the screen, and is island-shaped, and is smaller than the width of the wiring part, and as mentioned earlier, the wiring part within the screen is shielded from light by the light-shielding part of the color filter. has been
Since the pattern made of spacers is not visible within the screen, the image quality is good. The wiring portion is made of At or the like, and has a thickness of about 700 OA. The value of the compressive strength of Ae is much larger in a thin film form than in a bulk form. The specific compressive strength of Ae is approximately 0.25 kg/c in bulk form.
d or more, and in the case of a thin film, about 1 kHz/c+J or more. Therefore, even if an island-shaped spacer is formed on the wiring part, the pressing force is approximately 1 kg in the manufacturing process of the liquid crystal display device.
/cd, the wiring part will not be destroyed by pressure. Furthermore, when only a cylindrical spacer made of a glass component was dispersed, it was confirmed by visual inspection that the transistor part was destroyed and a point defect was caused, and it was also confirmed that the cylindrical spacer itself was destroyed. Furthermore, when only spherical plastic spacers were dispersed, it was confirmed that the spherical spacers were compressed and deformed due to compression. However, it was not possible to visually inspect the wiring for damage or spacer impressions. Furthermore, when an island-shaped spacer is formed on a wiring part, it is not possible to visually inspect the wiring part for destruction, as in the case of a cylindrical spacer made of glass or a spherical spacer made of plastic.

In addition, the method of applying a solution containing a mixture of spacers and adhesive onto a substrate with electrodes is by screen printing, which allows the adhesive to be formed into a thin film, and by curing the spacer, it can be applied onto the substrate. Can be fixed.

After forming spacers on the alignment film, alignment treatment is performed. The alignment processing method is known as the oblique vapor deposition method or the rubbing method. The rubbing method is a method in which the surface of the alignment film formed on the substrate is rubbed with a cloth such as nylon or rayon. This process is performed to give orientation to the liquid crystal molecules within the substrate.When the surface of the alignment film formed on the substrate was visually inspected after rubbing, it was found that approximately 1% of the spacers had fallen off.However, This degree of reduction in quantity had little effect on forming gaps in liquid crystal display devices.When using the rubbing method, it is appropriate to perform it after forming spacers on the surface of the alignment film.However, the oblique evaporation method When using, it may be performed either before or after forming the spacer on the surface of the alignment film.

In this example, a liquid crystal display device was manufactured using a rubbing method, and the image quality was evaluated.

If a spacer exists within a pixel, the spacer prevents the liquid crystal from existing, and in a state where it blocks light from a light source, light leaks out as an image, resulting in a defect in which stars appear to be in the night sky. Further, since the film thickness of the photosensitive resin mixed in the spacer was thin, no sagging was caused by coating around the spacer.

FIG. 3 shows a state in which a predetermined pattern has been formed. When doing this, the predetermined pattern 5 is connected to the wiring section 6 on the liquid crystal display board.
It was formed on the top and was made smaller than its width. On the opposite side of the liquid crystal display device, there is a color filter in which a light shielding part is formed, and the width of the predetermined pattern is sufficiently smaller than the width of the light shielding part formed in the color filter.

Furthermore, in this example, after forming a predetermined pattern on a liquid crystal display substrate, alignment treatment was performed, and it was confirmed that the image quality of the liquid crystal display device was good. A liquid crystal display device is completed by bonding a liquid crystal display substrate and a color filter on the opposite side with an intervening adhesive, and then injecting and sealing the liquid crystal.

As another example, a case in which a screen plate used for screen printing is made of a metal-coated film will be described with reference to the drawings. FIG. 4(a) is a plan view of a screen plate of a jig manufactured based on the manufacturing method of another embodiment of the present invention.
The front view is shown in FIG. 4(b). By using stainless steel for the screen plate and plating or coating its surface, good contact between the alignment film surface and the screen plate can be achieved. When, for example, coin chrome was used as the plating, the surface of the screen plate became very smooth and the surface of the alignment film was not damaged. As for the shape of the screen plate, the thickness of stainless steel is approximately 10
The thickness of the coin chrome was approximately 20 μm. However, the thicknesses of the stainless steel and coin chrome can be determined as appropriate depending on the shape of the predetermined pattern.

In addition, a resin film was used as a coating. Although acrylic, silicone, epoxy, etc. are thought to be suitable for the resin, epoxy resin was used in the present invention. Epoxy resin has excellent heat resistance and chemical resistance, and when pressed by screen printing, it can be elastically deformed, allowing for good printing.

As described above, according to this embodiment, since there is no pixel spacer within the screen of the liquid crystal display device, there is no light leakage and the image quality is good.

Effects of the Invention As described above, according to the present invention, the following effects can be obtained.

(1) By fixing the spacer to the surface of the alignment film other than the pixel portion on the substrate with electrodes, light extraction is reduced.

(2) Since there is no dripping or the like at the boundary between the alignment film surface and the spacer, good liquid crystal alignment can be obtained.

(3) A predetermined gap inside the liquid crystal display device can be precisely shaped.

(4) You can change the display device to a superior liquid crystal display.

(5) A large amount of processing can be performed relatively stably.

[Brief explanation of the drawing]

Figures 1a and b are a plan view and a front view of a screen plate used in the manufacturing method of the present invention, Figure 2 is a sectional view of a spacer that is an embodiment of the present invention, and Figure 3 shows the position of the spacer. FIGS. 4a and 4b are plan views of the substrate, and FIG. The figure is a cross-sectional view of the TPT element part and pixel part of the same liquid crystal display device, FIG. 7 is a plan view of the substrate showing the position of the spacer in the conventional example, and FIG. 8 is an enlarged view of the substrate in the conventional example showing the position of the spacer. FIG. 1... Hole, 2... Screen plate, 3... Spacer, 4... Adhesive, 5... Pattern, 6... Wiring part, 7... Stainless steel, 8... Coating , 9...Transparent electrode, 10...Alignment film, 11...Screen glass, 12.
...TFT element part, 13... Pixel part, 14... Orientation part, 15... Liquid crystal display substrate, 16... Sealing agent,
17...Liquid crystal, 18.19...Polarizing plate, 20...
Spacer, 21...TPT element section, 22... Wiring section, 23... Pixel section, 24... Gate line, 25.
26... Spacer, 27... Source line, 28.
29.30... Spacer, 31... Drain electrode,
32.33.34... Laminar spacer. Name of agent: Patent attorney Toshio Nakao (1 person) Figure 1 (cl) / Large (b) / ? Nuxthorn Ascension 2nd rl! J Figure 3 Figure 4 and 6 Otsu 2 (b) 8 Bound＼ 8 Membrane rupture Figure 7

Claims (4)

[Claims] (1) When manufacturing a calibrated liquid crystal display device from a set of electrode-equipped substrates, an alignment film formed on the electrode-equipped substrate, and a spacer fixed on the alignment film, the spacer and the adhesive are bonded together. 1. A method for manufacturing a liquid crystal display device, comprising the steps of: mixing the spacer and the adhesive; and forming an island-like region in which the spacer and the adhesive are mixed by screen printing. (2) The method for manufacturing a liquid crystal display device according to claim 1, wherein the screen used for screen printing has holes of a predetermined shape formed by etching. (3) The method for manufacturing a liquid crystal display device according to claim 1, wherein the screen used for screen printing is made of a metal film. (4) The method for manufacturing a liquid crystal display device according to claim 1, wherein the screen used for screen printing is made of a film coated with metal.