JPH01257823A - Color filter substrate for liquid crystal display device - Google Patents

Abstract

PURPOSE:To obtain a sharp display image with lower electric power consumption by disposing a transparent electrode to the upper part of color filters formed on a transparent substrate. CONSTITUTION:The transparent electrode 4 is disposed on the color filters 2 and a protective film 3 is interposed between the transparent electrode 4 and the color filters 2. The protective film 3 relieves the surface of the color filters 2 to facilitate the formation of the transparent electrode 4 and protects the surface of the color filters 2. The light from a back light is, therefore, transmitted through a polarizing plate 11 and thereafter, said light passes the layer of the liquid crystal 5 oriented by impression of a voltage between a TFT 8 and the transparent electrode 4 by an image signal; further, this light transmits through the color filter 2 and a polarizing plate 10, by which the color image is visually recognized. The sharper and finer image is thereby formed and the electric power consumption is reduced.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a color filter substrate for a liquid crystal display device used in a liquid crystal color television or the like.

[Conventional technology]

In recent years, LED, PDP, VFD, EL, and ECD.

While various flat displays such as flat CRTs and LCDs have been developed, LCDs (liquid crystal displays) are one step ahead of color displays and are now in practical use. Liquid crystal displays can be colored relatively easily by adding color filters, and have the advantage of being thin and lightweight. Moreover, up to 2
It can be driven with a low voltage of about 0V and is highly safe, so it can be used in a wide range of applications, from small to large, such as pocket TVs, portable TVs, office automation equipment, cars, and video camera viewfinders. The color LCD display has TPT,
There are active matrix methods such as MIM and simple matrix methods, but the current mainstream is the active matrix method of TPT. The liquid crystal sealed in the liquid crystal, transparent electrodes arranged on a transparent substrate, and TPT used as a switching element.
By applying a voltage between (I film transistor),
It is configured to control the transmission of light from the backlight emitted from behind the display, and to display color images using regularly arranged color filters of the three primary colors of red, blue, and green. . The color filter is a transparent electrode formed on a transparent substrate, JTO
A plurality of fine colored pixels of R (red), G (green), and B (blue) are arranged in a predetermined pattern on an electrode (transparent conductive film of indium tin oxide), and color mixing is done by humans. It is done visually on the retina of the eye.

Since a liquid crystal display is a one-to-one display, the pixel size of the color filter does not need to be smaller than the resolution of the eye, and is at least about 100 μm. As shown in FIG. 5, the pixel coloring pattern on this color filter includes a mosaic arrangement, a triangular arrangement, a striped arrangement, etc. Among these, the triangular arrangement is thought to display the image most naturally.

The characteristics required for color filters for liquid crystal displays include R, G, and B spectral transmittance characteristics, including the backlight and polarizing plate characteristics used.
C (National Te1evision Sys.
temCommittee color system
), it is ideal to use three primary colors based on the standards of color television systems such as . Furthermore, since the color filter is incorporated into the liquid crystal cell and comes into direct contact with the liquid crystal, it is necessary that it contains few ionic impurities and does not affect the liquid crystal. Furthermore, the manufacturing process of liquid crystal displays, such as forming a TTO electrode film, processing an alignment film,
Does not change during the sealing process, has low light loss, does not fade due to bank lights, etc., has a uniform pattern and spectral transmittance, has good relative pitch accuracy with the counter electrode, and is low cost. Certain things are required.

There are the following types of color filters depending on the method of forming them.

A) Dyeing method Car-fil-Dyeing method Color filters are formed by photolithography technology and dyeing technology, and the manufacturing methods are classified into multilayer method and single layer method. To form a color filter using the multilayer method, first, a new water-based resin such as gelatin, casein, finsugriux, polyvinyl alcohol, or polyacrylamide is added to the surface of a transparent glass substrate, and as a photosensitizer, dichromate, dichromate, Added chromate or diazo compound to 0.4
After coating to a thickness of about 2 μm, it is exposed to light through a mask of a predetermined shape, developed, and dyed with an acid dye or a reactive dye to form a first color color filter layer. Next, a resist dyeing layer of acrylic, urethane, epoxy, etc. is formed as an intermediate protective layer. Instead of forming an intermediate layer, there is also a method of using chemical treatment with tannic acid or the like. A similar process is performed to form R, G, and B color filters.

In the single layer method, the layer to be dyed is formed in a continuous type without forming an intermediate layer, and dyed with R and C1B through a masking layer to form a color filter. There is a method in which the layer to be dyed is formed separately and dyed in the same way through a masking layer. With the former, bleeding of the dye to its neighbors is a problem.

B) ＼ Method Kerr Filter Dispersion method color filters are formed by photolithography technology after coating a transparent photosensitive resin with a photosensitive liquid containing dyes, organic pigments, and inorganic pigments dispersed as colorants on a substrate. Creates highly accurate color filters. Compared to dyed color filters, this method has the advantage of simplifying the formation process and providing highly accurate filters.

C) Heavy-duty filter - A color filter formed by applying voltage to a patterned transparent electrode to deposit ionized pigment dispersed in water onto the transparent electrode, which is repeated for each color.

D) Kerr Filter by Shō method Sublimable pigments or dyes are deposited on a transparent substrate in a high vacuum, and a color filter is obtained by a lift-off method or an etching method, or a low refractive index material such as MgF=Sin□ is used. and ZrOz, Ti(h, ZnS, CeO
After forming a multilayer interference thin film by alternately depositing 7 to 11 layers of high refractive index materials such as □, the process of obtaining a color filter by a lift-off method or an etching method is repeated for each color.

E) Method Kerr-Furter It is obtained by dispersing highly transparent pigments or dyes in a vehicle and repeating processes such as screen printing and offset printing for each color.

Although there are problems with dimensional accuracy, it is one of the promising color filters, along with dispersion method color filters, for use in color liquid crystal displays, where increasing size and cost reduction are issues.

In addition, in LCD color TVs, etc., black patterns are provided at the boundaries between adjacent colored pixels of color filters and at the outer periphery of the display screen, especially to improve the contrast and saturation of the displayed image, and as a light-shielding mask around the periphery of the screen. things are being done.

In addition to the printing method used to form the black pattern, a black colored negative photosensitive resin is applied to the entire surface of the transparent substrate after the R, G, and B colored pixels have been formed. Method of developing after exposure from the opposite side, applying dyeable negative photosensitive resin instead of black colored negative photosensitive resin, developing in the same way, and then coloring the obtained photosensitive resin image black with dye. A positive photosensitive resin is applied in the same manner, exposed and developed to form a resin image of the same shape as the colored pixels on the R, G, and B colored pixels, and then a black resin or a metal such as chrome is applied on top of this. A method is used in which a thin film is deposited and then the photosensitive resin is removed. In addition, when chromium is deposited, a black pattern is obtained by subjecting the chromium film to a blackening treatment.

Further, the inner peripheral edge of the transparent substrate is adhesively sealed with a spacer to form a section in which liquid crystal is sealed.

[Problem to be solved by the invention]

In recent years, as color filter substrates for liquid crystal display devices have come to be used in ultra-small liquid crystal color televisions, etc., color filter substrates for liquid crystal display devices have become more and more popular. There has been a demand for lowering the manufacturing cost of the substrate itself, and it has been difficult to meet this demand with the structure of conventional color filter substrates for liquid crystal display devices. That is, as shown in FIG. 4, a conventional color filter substrate for a liquid crystal display device has a transparent electrode provided on a transparent substrate, a color filter formed thereon, and a layer for protecting the filter. It was coated with a protective film. In this configuration, there are color filters and protective films between the transparent electrodes that apply an electric field to the liquid crystal and the liquid crystal, so there is a large voltage drop in these parts, so a high voltage is required to obtain a clear image. required, and the power consumption was also large.

[Purpose of the invention]

The present invention provides a novel color filter for liquid crystal display devices that achieves clearer and finer images and lower power consumption, which has been difficult to achieve with conventional color filter substrates for liquid crystal display devices, which have the above-mentioned problems. The purpose is to provide a filter substrate.

[Means to solve the problem]

FIG. 1 shows a cross-sectional view of a color liquid crystal display constructed using a color filter substrate for a liquid crystal display device according to an embodiment of the present invention, in which 1.9 is a transparent substrate, 2 is a transparent substrate;
is a color filter, 3 is a protective film, 4 is a transparent electrode, 5 is a liquid crystal, 6.7 is a spacer (sealing material), 8 is TPT (
10.11 is a polarizing plate. The color filter substrate of the present invention is characterized in that a transparent electrode 4 is arranged above the color filter 2, whereas conventional ones have a color filter or a protective film interposed between the transparent electrode and the liquid crystal. has. In the embodiment shown in FIG. 1, a protective film 3 is interposed between the transparent electrode 4 and the color filter 2. The protective film 3 alleviates unevenness on the surface of the color filter 2, making it easier to form the transparent electrode 4, and at the same time,
It plays the role of protecting the surface of the color filter 2. As a material for the protective film 3, conventional polyurethane-based polymers have low strength and become soft when heated.
Acrylic polymer is used because the electrode may wrinkle or peel during the process of forming the transparent electrode 4 film thereon. Since acrylic polymer has high strength and allows the protective film 3 to be made thin, it is possible to maintain high light transmittance. The protective film 3 may be omitted if the surface of the color filter 2 is smooth. Spacer (sealing material)6.
7 and the transparent substrate 1, the interval between the transparent substrates 1.9 (cell interval) is required to be minute (5μ) and highly accurate, so in order to avoid unevenness on the adhesive surface, In order to improve adhesion, it is preferable that the transparent electrode 4 in this portion be removed as shown in FIG. Note that a sealing material such as epoxy is used for the adhesive portion. The color filter 2, like the conventional one, has colored patterns R,
A pattern formed from G, B and a black pattern M can be adopted. Further, as in the embodiment shown in FIG. 2, in order to simplify the black pattern forming process, the black pattern M may be formed by overlapping colored layers of three or two colors among red, green, and blue. . Furthermore, as shown in FIG. 3, by providing a transparent resin layer on the transparent electrode 4 with a cross-sectional shape of a micro condenser lens L having a diameter extending over the adjacent red, green, and blue colored patterns of the color filter 2. By mixing the light that passes through each coloring layer, subtle color tones can be expressed on the display screen.

[For production]

In FIG. 1, light from a backlight (not shown) provided above the figure passes through a polarizing plate 11 and then passes through the TP.
A voltage is applied between the T (thin film transistor) 8 and the transparent electrode 4 according to an image signal, and the image signal passes through the layer of oriented liquid crystal 5, and further passes through the color filter 2 and polarizing plate 10, so that a color image is visually recognized. In the color filter substrate for a liquid crystal display device of the present invention, since the transparent electrode 4 disposed on the transparent substrate 1 side is disposed above the color filter 2, it is different from the conventional color filter substrate shown in FIG. As shown in the figure, no voltage drop occurs at the color filter or the protective film 3. Therefore, a signal voltage can be effectively applied only to the liquid crystal 5 portion. In this case, if the transparent electrode 4 disposed above the color filter 2 is removed at the bonded portion between the transparent base Fi1 and the spacer 6.7, the precision, sealing performance, and bonding strength of the bonded surface will be improved.

Further, as shown in Fig. 2, when the black pattern M of the color filter 2 is formed by overlapping colored layers of three or two colors among red, green, and blue, the step of forming the black pattern M is omitted. This has the advantage of reducing manufacturing costs and preventing gaps from forming between colored pixels.

Furthermore, as shown in FIG. 3, on the transparent electrode 4,
When a layer with a cross-sectional shape of a micro condenser lens L having a diameter spanning the coloring pattern of adjacent red, green, and blue pixels of the color filter 2 is formed of transparent resin, each colored pixel of red, green, and blue. The transmitted light is mixed when passing through the micro condenser lens L, and a color image closer to nature than that of the conventional one is obtained. Note that when using the micro condenser lens L, the light from the backlight serving as the light source is
Contrary to what is shown in the figure, the light is made to enter from the transparent substrate 1 side.

〔Example〕

Embodiments of the present invention will be described in detail below based on the drawings. FIG. 1 shows a cross-sectional view of a color liquid crystal display constructed using a color filter substrate for a liquid crystal display device according to an embodiment of the present invention. In the same figure,
(2) and 9 are transparent substrates made of glass (soda glass, quartz glass, etc.), transparent synthetic resin plate, transparent synthetic resin film (polyester, etc.), or the like. Reference numeral 2 denotes a color filter, which is formed with a colored pattern consisting of colored pixels R, 'G, and B of three colors, and a black pattern M as required. For R, G, 83 color colored pixels,
The color can be formed by repeating known processes such as the dyeing method, dispersion method, electrodeposition method, vapor deposition method, and printing method described above for each color.

- For example, as described in JP-A No. 60-237441, it is necessary to form a polyimide film in which a pigment is dispersed on the transparent substrate 1, then pattern-expose it, and then develop it. A method of repeating a number of times can be adopted.

In addition, as a method for forming the black pattern M, known methods such as the above-mentioned printing method, photolithography (dying method), and method of depositing a thin metal film such as chromium or a black resin are used. 3 is a protective film. So, on color filter 2,
It is coated with acrylic polymer. 4 is a transparent electrode, and an ITO film consisting of 90 to 95 wt% of indium oxide and 5 to 1 lht/wt% of tin oxide is sputtered.
A film formed by a vapor deposition method, a CVD method, etc., or a film formed by forming a tin oxide film by a vapor deposition method, a CVD method, etc. and then etched by a photolithography method to form an electrode pattern are used. 5 is liquid crystal, 6.7 is spacer, 8 is TP
T (thin film transistor), 10.11 is a polarizing plate. Moreover, as another method of forming the black pattern M,
As another embodiment of the present invention, as shown in FIG.
, G, and B, or by overlapping two colored layers. In this method, a colored layer of, for example, red pixels R is formed in a predetermined pattern on a transparent substrate 1, and then a transparent coating film (2) is coated. A colored layer of green pixels G is formed thereon in a predetermined pattern, and then covered with a coating film I in the same manner. Furthermore, a colored layer for blue pixels is formed in the same manner from above, and finally three layers of a protective film are formed. A black pattern M through which light does not pass is formed in the portion where the three colored layers overlap. In this part, the film thickness of the layer becomes thicker, and the distance between it and other parts is 2 to 3 μm.
However, by forming the protective film 3 to a thickness of about 2 μm, the surface unevenness can be suppressed to about 0.5 to 1 μm, which causes no practical problems. However, only the black pattern M on the outer periphery of the screen has a width of about 1 mm, so
When the three color layers overlap, the protective film 3 cannot absorb the unevenness, so only the black pattern M around the screen periphery is formed by overlapping two color layers, a red color layer and a blue color layer, to form a pseudo-black pattern. It is preferable to make the surface of the protective film 3 as flat as possible.

The protective film 3 has the function of smoothing the surface of the color filter 2 and protecting the colored layer. In order to form each color layer, a photolithography method can be used, and the coating film (2) is formed to a thickness of about 0.1 μm by a spin coating method using, for example, a thermosetting acrylic resin. do.

As the material of the protective film 3, thermosetting acrylic resin can be used like the covering film I.

Next, as still another embodiment of the present invention, the one shown in FIG. A transparent resin layer having a cross-sectional shape is provided. The method for forming the micro condenser lens L is as follows:
For example, a screen plate for stencil printing using a stencil made of resin or a thin metal plate on a screen made of stainless steel or polymer fibers, or a screen plate for stencil printing with holes formed in a thin metal plate using the stencil printing method. ,
Either by printing acrylic resin in a predetermined position, or by forming a concave part using an etching method on a metal or glass plate, and then filling the concave part with resin such as acrylic and transferring it so that it spans the three colored pixels. method can be applied.

Incidentally, the surfaces of the transparent electrode 4 and TPT 8 that are in contact with the liquid crystal 5 constituting the color filter substrate for a liquid crystal display device of the present invention are subjected to an alignment treatment, for example, by the method described in Japanese Patent Publication No. 15848/1983. . The method described in the above publication is to apply an aromatic polyamic acid solution to a part or the entire surface of a substrate having an electrode coating, and then heat treatment at a predetermined temperature to form a polyimide polymer coating. The electrode substrate is formed by forming the film and then subjecting the film to orientation treatment, and specific embodiments of this when applied to the present invention will be described below.

First, in order to apply the polyamic acid to the surfaces of the transparent electrode 4 and TPT 8 corresponding to the substrate, the polyamic acid is coated with dimethylformamide, dimethylacetamide,
It is dissolved in a solvent such as dimethyl sulfoxide or N-methylpyrrolidone to form a 0.01 to 40% solution, preferably 0.01% to 40% solution.
A dilute solution of less than 0.01 to 10% can be applied by brush coating, dipping, spin coating, spraying, or the like. After coating, a heat treatment is performed under heating conditions of 100° C. or more and less than 200° C., preferably 160° C. for 1 to 2 hours, and dried to form a polyimide polymer film on the surfaces of the transparent electrode 4 and TPT 8. Thereafter, the surface of the polymer coating is rubbed in a certain direction with a cloth or the like to perform a desired orientation treatment.

Transparent electrode 4 and TPT 8 subjected to alignment treatment as described above
The cells are assembled so that the rubbing directions are perpendicular to each other, and a nematic liquid crystal having positive dielectric anisotropy is sealed therein. And the polarizing plates 10 and 11
The respective deflection directions are the same as those of the transparent electrode 4 and TPT8.
The color filter substrate for a liquid crystal display device of the present invention is assembled by laminating the substrates parallel to the rubbing direction.

As the organic sealant for the cells constituting the spacers 6 and 7 of the color filter substrate of the present invention, an organic substance having a high curing temperature, such as an epoxy resin adhesive, can be used.

Further, as the liquid crystal of the color filter substrate of the present invention, a nematic liquid crystal compound having positive dielectric anisotropy can be used.

〔Effect of the invention〕

As explained above, according to the color filter substrate for a liquid crystal display device of the present invention, since the transparent electrode is disposed above the color filter formed on the transparent substrate, the transparent electrode is different from that of the conventional color filter substrate. There is no voltage drop caused by the color filter or protective film between the liquid crystals, and the image signal voltage can be effectively applied to the liquid crystal, providing a color liquid crystal display that can provide clear images with low power consumption. can do.

In addition, by removing the transparent electrode at the adhesive part between the transparent substrate and the spacer, it is possible to create a liquid crystal cell with high precision and excellent sealing performance. A process for forming a black pattern on the periphery of a display screen by overlapping colored layers of two or three of the three primary colors of red, green, and blue colored pixels. At the same time, it is possible to prevent gaps from forming between adjacent colored pixels, so that a good display image can be obtained.

Furthermore, by providing a layer made of transparent resin with a cross-sectional shape of a micro condenser lens on the transparent electrode, the light that has passed through pixels of different colors of the color filter is mixed at the condenser lens part. This makes it possible to express subtle color tones that are more natural than conventional color LCD displays.

[Brief explanation of the drawing]

FIG. 1 is a sectional view of a color liquid crystal display constructed using a color filter substrate for a liquid crystal display device according to an embodiment of the present invention, and FIGS. 4 is a sectional view showing an example of a conventional color liquid crystal display, and FIG. 5 is an example of pixel arrangement on a conventional color filter. FIG. 1.9... Transparent substrate 2... Color filter 3... Protective film 4... Transparent electrode 5... Liquid crystal 6.7... Spacer 8... TPT (thin film transistor) 10.11.・
・Polarizing plate R, G, B...Colored pixel M...Black pattern (colored pixel) ■...Coating film L...Micro condensing lens~ Applicant Dainippon Printing Co., Ltd. Agent Patent attorney Yusuke Hiraki Fig.

Claims (5)

[Claims] (1) A color filter substrate for a liquid crystal display device, characterized in that a transparent electrode 4 is arranged above a color filter 2 formed on a transparent substrate 1. (2) The color filter substrate for a liquid crystal display device according to claim (1), wherein the transparent electrode 4 is arranged on the color filter 2 with the protective film 3 in between. (3) Claim (1) characterized in that the color filter 2 is formed of a colored pattern and a black pattern.
) or (2), the color filter substrate for a liquid crystal display device. (4) The color filter substrate for a liquid crystal display device according to claim (3), wherein the black pattern is formed by overlapping colored layers of three or two colors among red, green, and blue. (5) A claim characterized in that a layer having a cross-sectional shape of a micro-condensing lens made of transparent resin and having a diameter spanning the adjacent red, green, and blue colored patterns of the color filter 2 is provided on the transparent electrode 4. The color filter substrate for a liquid crystal display device according to any one of items (1) to (4).