JPH07128514A - Color filter for liquid crystal display device - Google Patents

Abstract

PURPOSE:To provide the color filter which does not generate hindrance in liquid crystal driving without requiring smoothing layers by constituting transparent colored layers of ink contg. coloring pigments and specifying the difference between the max. film thickness and min. film thickness in the pixel parts of the transparent colored layers. CONSTITUTION:This color filter for the liquid crystal display device consists of a substrate 1 and plural colors of the transparent colored layers 2R, 2G, 2B disposed by selectively printing in the pixel parts of this substrate 1. The transparent colored layers 2R, 2G, 2B are formed of the ink contg. the coloring pigments at <=44 pts.wt. per 100 pts.wt. resin and are so formed that the difference between the max. film thickness and the min. film thickness in the pixel parts of the transparent colored layers 2R, 2G, 2B is <=0.6mum. Consequently, the disconnection of transparent electrodes and unequal rubbing of oriented films are prevented by directly laminating the transparent electrodes and oriented films thereon without applying the smoothing layer. The printing ink prepd. by mixing the heat resistant org. coloring pigments with the resin, such as epoxy resin, is usable as the printing ink.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a color filter applied to a color liquid crystal display device or the like, and more particularly to a color filter which can favorably drive a liquid crystal without causing disconnection of a liquid crystal driving transparent electrode.

[0002]

2. Description of the Related Art A color liquid crystal display device drives a liquid crystal by enclosing a liquid crystal substance in a cell between a front substrate and a rear substrate and applying a voltage for each pixel between the front substrate and the rear substrate. The screen is displayed by controlling the light transmission. Such a color liquid crystal display device has, for example, a structure as shown in FIG. That is, in FIG.
Reference numeral 1 denotes a transparent substrate a1 such as a glass plate. The transparent substrate a1 and the transparent substrate a1 are arranged in a pixel pattern on a display portion substantially in the center of the transparent substrate a1, and the transmitted light is transmitted to each pixel in a desired color (for example, A color filter is composed of a transparent coloring layer a2 for coloring red, green, and blue (the three primary colors of light) and a transparent electrode a4 provided on the transparent coloring layer a2 for applying a voltage to the liquid crystal substance e. An alignment film b of the liquid crystal substance e, the surface of which has been rubbed, is arranged on the inner surface side (a surface in contact with the liquid crystal substance e) of the color filter, and a polarizing film (not shown) is attached to form the back substrate. Further, the front substrate is mainly composed of a transparent substrate c1 such as a glass substrate, a transparent electrode c2 and an alignment film c3 which are sequentially provided on the transparent substrate c1, and includes a polarizing film (not shown). There is. Each of the transparent electrodes a4 and c2 is patterned in a wiring pattern so that a voltage can be applied to each pixel, and the ends thereof are guided to the outside of the liquid crystal display device through the seal portion. , Is connected to an external device at this guiding portion.

The front substrate and the rear substrate are heat-sealed and hermetically sealed by a seal member d at a peripheral portion of the front substrate and the rear substrate with a gap therebetween. The above liquid crystal display device is configured by enclosing a liquid crystal substance in the (cell). Then, a driving voltage is applied between the transparent electrodes a4 and c2 for each pixel by an external voltage input from the induction portion to control the alignment direction of the liquid crystal substance and the polarization plane of transmitted light accompanying it.
Two polarizing films (not shown) are used to control transmission / non-transmission of the above-mentioned polarized light for screen display.

By the way, there are various known methods for forming the transparent colored layer a2 of the above-mentioned color filter applied to this liquid crystal display device, but in view of high productivity and low cost, the intaglio offset is used. A printing method such as a printing method is often used.

However, the transparent colored layer a2 formed by this printing method has a substantially semi-cylindrical cross-sectional shape in which the central portion is thicker than the peripheral portion due to the method of forming the transparent colored layer a2. The difference between the maximum film thickness and the minimum film thickness (effective film thickness difference) Y (see FIG. 5) reaches approximately 1.0 to 1.5 μm. The transparent electrode a4 is broken because it is formed along the irregularities of the transparent colored layer a2, or the cross-sectional shape is reproduced on the surface of the alignment film b on the transparent electrode a4 and the uniform rubbing treatment is performed. Sometimes becomes difficult to drive the liquid crystal.

In order to avoid such inconvenience, in general, a smoothing layer a3 made of a transparent resin is applied on the transparent colored layer a2 and the transparent electrode a4 is laminated thereon.

[0007]

However, according to this method, the manufacturing process is complicated and the cost is increased due to the increase in the step of forming the smoothing layer a3, and the smoothing layer a3 is formed. There has been a problem in that a defective product is produced due to bounce or entrainment during spin coating, or foreign matter is mixed in, and the yield in color filter production is reduced.

The present invention has been made on the basis of such a technical background. An object of the present invention is to drive a liquid crystal without the need for a smoothing layer because the surface of the transparent colored layer is smooth. The object is to provide a color filter that does not cause any problems.

[0009]

According to the study by the present inventors, the cross-sectional shape of the transparent colored layer is related to the ratio of the resin component and the color pigment contained in the transparent colored layer. There is. That is, FIG. 3 shows the difference in effective film thickness when intaglio offset printing is performed by changing the mixing ratio of the color pigment with respect to this resin component. As is clear from FIG. 3, as the color pigment component increases, the effective film thickness increases substantially in proportion to the weight of the color pigment component. Then, when performing a single regression analysis based on this FIG. 3,
It has been found that the relationship is expressed by the following equation, where the effective film thickness difference is Y μm and the weight ratio of the color pigment to the resin (color pigment / resin) is X%.

Y = 0.079 + 1.197X / 100

Then, for example, a TFT (Thin Film Tran
In a liquid crystal display device of a driving system, in order to prevent the disconnection of the transparent electrode and the rubbing unevenness of the alignment film and drive the liquid crystal material well to enable a clear screen display, the above-mentioned effective The film thickness difference Y may be 0.6 μm or less.
Then, when X is calculated based on the above equation when Y = 0.6 μm, X = 44%.

The invention according to claim 1 is based on such a technical study. That is, the invention according to claim 1 is a color filter for a liquid crystal display device, comprising a substrate and a transparent colored layer of a plurality of colors provided by selectively printing on a pixel portion of the substrate, wherein the transparent colored layer is It is composed of a printing ink containing 44 parts by weight or less of a coloring pigment with respect to 100 parts by weight of a resin, and the difference between the maximum film thickness and the minimum film thickness in the pixel portion of the transparent colored layer is 0.6 μm or less. It is characterized by. In such a technical means, as the printing ink constituting the transparent colored layer, an epoxy resin, a melamine resin, or both of the epoxy resin and the melamine resin is used as a resin, and a heat-resistant organic coloring pigment in the resin is mixed. You can use what you have done.

The printing method is preferably the intaglio offset printing method from the viewpoint of not damaging the substrate during printing and the stability of the ink transfer amount and the reproducibility of the printing shape.

In the invention according to claim 1, a glass plate, a plastic sheet or the like can be used as the substrate.

When the color filter according to the present invention is applied to the back electrode plate of a reflective liquid crystal display device, the light reflectance is increased to enable a bright screen display, or specular reflection is prevented to cause fluorescence. In order to prevent a virtual image of an external light source such as a lamp, it is desirable to provide a metal reflection film or a light scattering film or both of these metal reflection film and the light scattering film between the substrate and the transparent colored layer.

The inventions according to claims 2 and 3 are made for such technical reasons.

That is, the invention according to claim 2 is based on the invention according to claim 1, and is characterized in that a metal reflection film is provided between the substrate and the transparent colored layer.
The light reflectance is increased to enable a bright screen display.

The invention according to claim 3 is based on the invention according to claim 1 or 2, and is characterized in that a light scattering film is provided between the substrate and the transparent colored layer or on the transparent colored layer. A screen that can prevent a virtual image of an external light source such as a fluorescent lamp from being generated in the screen and be observed in duplicate with the display image, and can display only the display image in the screen. Display is possible.

As the metal reflection film according to the second aspect, a metal thin film formed on the substrate by a method such as vacuum deposition or sputtering can be used. As the metal, those having a high light reflectance are preferable, and aluminum, silver, titanium, magnesium and the like can be used, and an alloy of these metals can also be used.

Further, as the light scattering film according to claim 3,
A film composed of a transparent resin and transparent particles dispersed in the transparent resin and having a refractive index different from that of the resin can be used. As such a resin, for example, an acrylic resin, an epoxy resin, an acrylic epoxy resin, a polyester resin, a polyvinyl alcohol resin, a polystyrene resin, a silicon resin, or the like can be used. When the light-scattering layer is patterned in the same shape as the pixel, it is desirable to use a radical-polymerization type or cation-polymerization type UV-curable radical-polymerization type resin or cation-polymerization type resin as the resin. . Further, it is also possible to carry out the above patterning by using a resin having ultraviolet curability and thermal polymerization property.

Examples of the transparent particles used for the light scattering layer include metal oxides such as titanium oxide, zirconium oxide, lead oxide, aluminum oxide, silicon oxide, magnesium oxide, zinc oxide and barium oxide, or Metal nitride, metal fluoride, etc. can be used. Further, it is also possible to use organic particles such as polytetrafluoroethylene, polyether sulfone, polyether ether ketone, polysulfone, polyimide, polydivinylbenzene and the like.

[0022]

According to the invention of claims 1 to 3, the transparent colored layer is composed of a printing ink containing 44 parts by weight or less of a coloring pigment with respect to 100 parts by weight of the resin, and the pixel portion of the transparent colored layer. The difference between the maximum film thickness and the minimum film thickness at 0.
Since the thickness is 6 μm or less, the transparent electrode and the alignment film can be directly laminated without coating a smoothing layer on the transparent electrode to prevent disconnection of the transparent electrode and uneven rubbing of the alignment film.

[0023]

【Example】

Example 1 In this example, as shown in FIG. 1, a glass substrate 1 was formed on the glass substrate 1 by intaglio offset printing with a width of 100 μm.
A transparent colored layer 2 of three colors (three primary colors of red, green, and blue light) with a film thickness of about 2 μm printed on the striped pixel portion of m.
R, 2G, and 2B. And
The red transparent coloring layer 2R is made of an ink containing 32 parts by weight of a coloring pigment with respect to 100 parts by weight of a resin, and a green transparent coloring layer 2G.
Is an ink containing 31 parts by weight of a color pigment with respect to 100 parts by weight of a resin, and the blue transparent colored layer 2B is an ink containing 19 parts by weight of a color pigment with respect to 100 parts by weight of a resin.
It is configured.

When the effective film thickness difference of this color filter was measured, the results almost matched with the graph of FIG. 3 were obtained. Further, when a transparent electrode and an alignment film were sequentially laminated on this and subjected to a rubbing treatment, there was no disconnection of the transparent electrode and no rubbing unevenness.

[Embodiment 2] In this embodiment, as shown in FIG. 2, a glass substrate 1 and a 0.2 μm-thick aluminum metal reflection film 3 vacuum-deposited on a rectangular pixel portion thereon. Further, a light-scattering film 4 which is applied on the light-scattering transparent epoxy resin and in which titanium oxide having a particle diameter of 0.1 μm is dispersed, is printed on the light-scattering film 4 by an intaglio offset printing method. And a transparent colored layer 2R, 2G, 2B of three colors (three primary colors of red, green and blue lights) having a film thickness of about 2 μm.

The metal reflection film 3 and the light scattering film 4 are formed by the following method. That is, first, the metal reflection film 3 is formed on the glass substrate 1, and then the light scattering film 4 is spin-coated, and then the light scattering film 4 is exposed and developed in a pattern to be patterned into a pixel pattern. It was heated and cured, and then the exposed metal reflection film 3 was patterned by etching.

The transparent colored layers 2R, 2G and 2B are formed in the same manner as in the first embodiment.

[0028]

According to the inventions of claims 1 to 3, the transparent electrode and the alignment film are directly laminated without coating the smoothing layer on the transparent colored layer, and the transparent electrode is disconnected. Since it is possible to prevent uneven rubbing of the alignment film, there is an effect that a high-quality color filter that does not hinder the driving of the liquid crystal can be manufactured at high yield and at low cost.

[Brief description of drawings]

FIG. 1 is an explanatory cross-sectional view of a color filter according to an embodiment.

FIG. 2 is an explanatory cross-sectional view of a color filter according to an example.

FIG. 3 is a graph showing the relationship between the ratio of color pigments and the effective film thickness difference.

FIG. 4 is an explanatory cross-sectional view of a conventional color liquid crystal display device.

FIG. 5 is an explanatory diagram for explaining an effective film thickness difference.

[Explanation of symbols]

 1 glass substrate 2R, 2G, 2B transparent colored layer 3 metal reflective film 4 light scattering film

Claims (3)

[Claims] 1. A color filter for a liquid crystal display device comprising a substrate and a transparent colored layer of a plurality of colors provided by selectively printing on a pixel portion of the substrate, wherein the transparent colored layer is 100 parts by weight of resin. On the other hand, a liquid crystal comprising a printing ink containing 44 parts by weight or less of a coloring pigment, and the difference between the maximum film thickness and the minimum film thickness of the transparent colored layer at the pixel portion is 0.6 μm or less. Color filter for display device. 2. The color filter for a liquid crystal display device according to claim 1, further comprising a metal reflective film between the substrate and the transparent colored layer. 3. A light scattering film is provided between the substrate and the transparent colored layer or on the transparent colored layer.
Alternatively, the color filter for liquid crystal display device according to item 2.