JPH01277803A - Color filter - Google Patents

Abstract

PURPOSE:To enable the formation of picture elements with good accuracy and to uniformize the film thickness of ink by printing ink layers of multiple colors having a prescribed pattern on a glass substrate the surface of which is a porous layer. CONSTITUTION:The ink layers of many colors having the prescribed pattern are printed on the glass substrate the surface of which is the porous layer. For example, an SiO2 component and Na2-B2O3 are separated in phase by heating borosilicate glass of an Na2-B2O3-SiO2 system. The Na2-B2O3 glass phase elutes and the porous glass of the SiO2 component having pores is obtd. when this glass is immersed in an acid soln. or hot water. The pores of the glass are variable up to several tens - several thousands Angstrom and the ink layers of the many colors having the prescribed patterns are formed on the porous glass having the pores within this range. The printed color filter which has the good shape accuracy of the picture elements and has no unequalness in the ink thickness is thereby obtd.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application] The present invention relates to a color filter used in a color liquid crystal display element.

[Conventional technology]

Color filters are being applied to color video cameras in combination with image pickup tubes and solid-state image sensors, and are also being applied to color display devices.

A color filter is one in which color mosaics or color stripes colored in three primary colors are arranged on a six-bright substrate such as glass based on a predetermined pattern.

For example, in the case of printed color filters, color filters are printed on a glass substrate as a transparent substrate, using lithography, letterpress, intaglio, etc.
It is made by forming ink in the five primary colors of red, green, and blue into a predetermined pattern using printing techniques such as gravure, screen, and flexible printing.

The shape 1 position accuracy of each color pixel of the color filter varies depending on the size of the display used. for example,
In the case of a color liquid crystal TV of a non-die type (screen size is around 5 inches), the required shape nine position accuracy for each color is within ±10 μm, preferably within ±5 μm.

Also, the ink thickness of each color pixel of the printed color filter is
2 to 3 μm is necessary. The reason for this is that the ink is of a pigment dispersion type, and unless it is thicker than a certain level, it will not produce a sufficiently deep color, making it unsuitable for use as a color filter for color liquid crystal TVs.

[Problem to be solved by the invention]

When printing ink on glass, compared to paper,
Ink transferability is extremely poor. As a result, 1) pixels do not have a predetermined shape.

2) Unevenness occurs in the ink thickness of pixels.

There was an issue.

[Means to solve the problem]

In order to solve this problem, the present invention is characterized in that ink layers of multiple colors having predetermined patterns are formed by printing on a glass substrate whose surface is a porous layer.

[Effect]

The poor printing suitability of glass stems from the lack of pores on the glass surface compared to paper.

The ink is a chicken-tropic fluid, and its viscosity decreases as shear stress increases or as time passes under stress.

In normal printing, the shear rate is high and the viscosity is low in the ink layer on the cylinder near the cylinder and the substrate to be printed. The ink layer adhering to the cylinder breaks at a point where the ink viscosity is low and is transferred to the printing medium.

In the case of a substrate without pores such as glass, the viscosity is lowest in the area closest to the substrate to be printed.

Transferability deteriorates.

On the other hand, a printing substrate such as paper has micropores on its surface, and the moment it receives the printing pressure of the ink, a portion of the vehicle separates from the pigment and is absorbed and filtered by the porous surface of the paper. . This results in a higher pigment concentration in the area closer to the paper, and therefore higher viscosity.

For this reason, to put it simply, the ink is cut off at a place with low viscosity near the cylinder, which improves transferability.

The same can be said when using a glass substrate whose surface is a porous layer.

There are many glass substrates having a porous layer on the surface, such as Corning's Vycor type porous glass. Examples include: 1) Vycor type porous glass 2) PPG porous glass 3) aeo, -5Mb, 03 type porous glass 4) Si
O,・p, o, system porous glass 5) Sint-Ge
O, based porous glass 6) Shirasu porous glass 7) Porous glass obtained from alkali-free glass 8) Porous glass containing heavy metal oxides 9) Mullite based porous crystal glass 10) Porous high silicic acid foam There's glass.

Porous glass utilizes the phase separation phenomenon of glass.

Taking Ha, 0-820l-8iO1-based borosilicate glass as an example, by heating the glass, it becomes 810. Components and N
Phase separate ano-B201. When this phase-separated glass is immersed in an acid solution or hot water, Ha, O-B,
O, glass phase is eluted and S10. with pores. A porous glass of the components is obtained.

The pore size of glass varies depending on the glass components and heat treatment temperature. In addition, by immersing the porous glass in an alkaline solution after making it, S10. It is also possible to increase the pore size by dissolving the components.

The pore diameter can vary from several tens to several thousand angstroms, and the pore diameter of the glass substrate of the present invention may be any size within this range.

By forming a multi-color ink layer with a predetermined pattern on this porous glass, a printed color filter with good pixel shape precision and uniform ink thickness can be obtained.

Next, a detailed explanation will be given using examples.

[Comparative example]

Pixels each having a side of 200 μm were printed on mirror-surfaced borosilicate glass by an offset printing method.

The ink used is TK mark viL manufactured by Toyo Ink Co., Ltd.
Met. Compared to the pixel shape of the PS version used, the average shape of the pixels varied by ±30 μm or more. In addition, in FIG. 2, to show the transferability of ink,
The ink thickness of an arbitrarily selected pixel on glass was measured along the cross section of the pixel.

As can be seen from Figure 2, there is variation in the thickness of the ink within the pixel, and the ink is not transferred to significant areas, making it unusable as a color filter.

〔Example〕

(Example 1) A mirror-like bororic acid glass substrate was fired at 550° C. for 1 hour to cause phase separation into SiO□ components and B, O, —NO, 0 components.

The ingredients of borosilicate glass are Met.

This phase-separated borosilicate glass M plate 9.

The B, O, -Na20 phases were eluted by immersion for 50 minutes in a 3N sulfuric acid solution heated to .degree.

As a result, this glass substrate became a porous glass substrate with an average pore diameter of 100X.

Pixels each having a side of 200 μm were printed in a predetermined pattern on this substrate by offset printing in the same manner as in the comparative example.

The ink used in the comparative example was used as blue.

Compared to the pixel shape of the PS version used, the average shape of the pixels had a shape variation of ±10 μm or less. Further, in order to show the ink transferability in FIG. 1, similar thickness measurements were carried out as a comparative example.

Ink is transferred uniformly to pixels, ensuring pixel shape accuracy,
The thickness of the ink was within a range that could be used as a color filter. After that, red and green inks were similarly printed in a predetermined pattern.

Both the pixel shape and the ink thickness are the same as for blue, making it usable as a color filter.

(Example 2) Borosilicate glass having the same composition as Example 1 was heated at 550°C for 24 hours.
By firing for a time, the components of 3102 and B, O, -Na,
The O component was phase separated.

This phase-separated borosilicate glass substrate was immersed for 2 hours in a 5N sulfuric acid solution heated to 90° C., and then immersed in a 10N hydroxide solution for 1 hour. This is K
Therefore, this glass substrate was a porous glass substrate with an average pore diameter of about 250 pores, and pixels each having a side of 200 μm were printed in a predetermined pattern in the same manner as in Comparative Example 1.

The shape and ink transferability were the same as in Example 1 and within the range that could be used as a color filter. after this,
A predetermined pattern was printed with red and green ink in the same way as with blue ink.

Both the pixel shape and the ink thickness are the same as for blue, making it usable as a color filter.

(Example 3) N a20-By O, -Oe O, -3N b, 0
5 Using a glass substrate made of yarn, heat treatment at 600°C for 12 hours to phase separate and crystallize it, and immerse it in sulfuric acid at 90°C for 1 hour according to the 5 rules to obtain N a 20 B 20 s.
The phase was eluted. As a result, a glass substrate having an average pore diameter of aooX was obtained.

This substrate was coated with a side of 200 μm in the same manner as in Comparative Example 1.
pixels were printed in a predetermined pattern.

The shape and ink transferability were the same as in Example 1 and within the range that could be used as a color filter. After that, red and green inks were printed in a predetermined pattern in the same way as blue ink.

Both the pixel shape and the ink thickness are the same as for blue, making it usable as a color filter.

〔Effect of the invention〕

As can be seen from the above examples, the color filter made of natural resin had good ink transferability, so the pixel shape could be formed with high precision, and the ink film thickness was also uniform.

This made it possible to print color filters stably and with high precision.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing the film thickness of an ink pixel of a force 2 filter formed according to the present invention. a) Measurement location of ink film thickness b) Distribution of ink film thickness tA2 Figure is Ink II! of a color filter formed by the conventional method. A diagram showing the film thickness of Il'Jg. a) In 1? Film thickness measurement site b) Distribution of ink film thickness Applicant Seiko Epson Co., Ltd. Agent Patent attorney Kenzo Suzuki (and 1 other person) Figure 1 Figure 2

Claims (1)

[Claims] A color filter characterized in that ink layers of multiple colors having predetermined patterns are formed by printing on a glass substrate whose surface is a porous layer.