JP2008249947A - Color filter, and lateral electric field drive type liquid crystal display device using the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a color filter which suppresses the occurrence of a display defect caused by green pigment, and to provide a lateral electric field drive type liquid crystal display device using the color filter. <P>SOLUTION: In the color filter having a transparent substrate, a black matrix layer, colored layers colored in colors of red, green, and blue, and a transparent protective layer covering the black matrix layer and colored layers, the green-colored layer is made less in film thickness than the red- and blue-colored layers and the transparent protective layer is formed on the respective colored layers so that the sums of film thicknesses of the respective colored layers and the transparent protective film formed thereupon are nearly equal to one another; and the lateral electric field drive type liquid crystal display device using the color filter. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a color filter and a horizontal electric field drive type liquid crystal display device using the color filter.

  As a liquid crystal display device having high image quality, an active matrix liquid crystal display device using a thin film transistor (hereinafter referred to as “TFT”) as a pixel switching element is known. An active matrix liquid crystal display device is characterized by being thin, lightweight, and low power consumption. In addition, the active matrix liquid crystal display device can provide high contrast and high-speed response. For this reason, it is widely used for small display devices such as mobile phones and PDAs, displays for portable computers and desktop computers, and displays for television receivers.

  A conventional liquid crystal display device is operated by a twisted nematic (TN) method in which aligned liquid crystal molecules are rotated in a direction perpendicular to a transparent substrate. However, the TN liquid crystal display device has a narrow viewing angle. For this reason, liquid crystal display devices such as a lateral electric field method (In Plane Switching: IPS method) and a vertical alignment method (Virtual Alignment: VA method) having excellent viewing angle characteristics have been developed.

  As shown in FIG. 3, in the IPS liquid crystal display device 100, the liquid crystal sandwiching layer 130 between the first transparent substrate 110 on which the TFT is formed and the second transparent substrate 120 on which the color filter 121 is formed is provided. The liquid crystal molecules 132 are sandwiched.

  On the first transparent substrate 110, scanning lines and signal lines (not shown) are formed substantially orthogonally. TFTs (not shown) are arranged in a matrix at these intersections, and pixel electrodes 112 and common electrodes 111 are alternately formed in a comb-like shape in each pixel. An interlayer insulating film 113 that covers the common electrode 111 is formed on the common electrode 111. A protective film 114 that covers the pixel electrode 112 is formed on the pixel electrode 112. An alignment film 115 is formed on the surface of the first transparent substrate 110.

  In addition, the second transparent substrate 120 includes a black matrix 122 formed so as to partition a pixel region, a colored layer 123 of three primary colors of a red colored layer 123R, a green colored layer 123G, and a blue colored layer 123B, and a transparent protective layer. A color filter 121 including the film 124 is formed. An alignment film 124 is formed on the surface of the transparent protective film 124.

  Liquid crystal molecules 132 that are homogeneously aligned with a predetermined angle in the longitudinal direction of the pixel electrode 112 are sandwiched between the liquid crystal sandwich layers 130. A polarizing plate (not shown) is provided outside the first transparent substrate 110 and the second transparent substrate 120. In the IPS liquid crystal display device 100, a potential is written to the pixel electrode 112 through the TFT, and a horizontal electric field is applied between the pixel electrode 112 and the common electrode 111 to form an electric field 131 parallel to the substrate surface. The amount of transmitted light is controlled by changing the alignment direction of the liquid crystal molecules 132.

  However, the IPS liquid crystal display device has different problems from the TN liquid crystal display device and the VA liquid crystal display device. In the IPS liquid crystal display device, the common electrode is not formed on the second transparent substrate on which the color filter is formed. For this reason, the IPS liquid crystal display device has a problem that it is directly affected by the electrical characteristics of the color filter pixels to cause display defects.

  One cause of display defects is copper phthalocyanine that constitutes the green colored layer of the color filter. This is believed to be due to copper phthalocyanine being an ionic substance. A method for solving a display defect caused by a green colored layer has been proposed (see, for example, Patent Documents 1 to 5). As a display defect caused by the green colored layer, there is known a red unevenness in which light transmitted through the green colored layer is reduced and the entire display screen looks reddish.

  Copper phthalocyanine pigments are photoconductive. For this reason, when a lateral electric field that drives liquid crystal molecules penetrates the color filter, a photocharge of copper phthalocyanine is generated and accumulated in the colored layer, thereby disturbing the lateral electric field. Patent Document 1 proposes preventing red unevenness by defining the content ratio of a copper phthalocyanine pigment.

  Further, Patent Document 2 describes that liquid crystal alignment failure and switching threshold shift are caused by the fact that the dielectric characteristics of green pixels are different from those of other color pixels. In order to solve this problem, this document defines a dielectric loss tangent (tan δ) of two layers in which a green layer and an overcoat layer made of a transparent resin are laminated. Specifically, it has been proposed that the concentration of the halogenated copper phthalocyanine, which is a green pigment, is reduced below a certain level, or the purity of the halogenated copper phthalocyanine is improved to lower the dielectric loss tangent value.

  Also in Patent Document 3, it is described that the alignment failure of the liquid crystal and the switching threshold shift are caused by the fact that the dielectric characteristics of the green pixel are different from those of the other color pixels. In this document, in order to solve this, the dielectric loss tangent (tan δ) of the green layer is defined. Specifically, it has been proposed that the concentration of the halogenated copper phthalocyanine, which is a green pigment, is reduced below a certain level, or the purity of the halogenated copper phthalocyanine is improved to lower the value of the dielectric loss tangent.

  Patent Document 4 describes that the influence of the green pigment contained in the green pattern is large as the cause of the occurrence of reverse twist. In this document, in order to solve this, specifically, the product of the content of the green pigment in the total pigment contained in the green pattern, the thickness of the green pattern, and the content ratio of the pigment in the green pattern, It has been proposed to take a predetermined value.

Patent Document 5 proposes replacing chlorine 16-substituted product of copper phthalocyanine, which is a pigment, or 50% or less of the chlorine with bromine for the purpose of preventing the occurrence of reverse twist.
JP 2003-295171 A JP 2004-117537 A JP 2006-113099 A JP 2003-315780 A JP 2004-69744 A

  However, the effects of copper phthalocyanine cannot be excluded even if the techniques described in Patent Documents 1 to 5 are used. As apparent from FIG. 3, the lateral electric field 131 directly affects the green colored layer 123 </ b> G even when the concentration of the green pigment in the green colored layer 123 </ b> G, the chlorine content, and the like are controlled.

  In particular, when a liquid crystal display device is used as a television receiver, it is necessary to conform to the NTSC (National Television System Committee) color reproducibility range standard (compared to the NTSC color reproduction region). Conventional color liquid crystal display devices have been manufactured so that the NTSC ratio is about 40 to 60%. However, it is necessary to improve the NTSC ratio in order to expand the application of the color liquid crystal display device to a thin television receiver or the like. In particular, in order to conform to the EBU (European Broadcasting Union) method adopted by Europe, it is necessary to manufacture so that the NTSC ratio is 72%. In order to improve the NTSC ratio, it is necessary to increase the amount of the pigment in the colored layer. In the method described in the above patent document, it is necessary to increase the thickness of the colored layer. This creates a problem that makes processing difficult.

  Fluorine also affects brightness. For this reason, as described in Patent Document 5, when chlorine is substituted with fluorine, there is a problem that the brightness of the liquid crystal display device is lowered.

  As a method for reducing the strength of the transverse electric field applied to the color layer even in the case of high color purity without sacrificing workability, the transparent protective film is made thicker and the distance between the electrode and the color layer is increased. A method is conceivable. The transparent protective film is usually formed to a thickness of 1 to 3 μm. If the transparent protective film is thickened, the distance from the electrode is increased. As a result, the influence of the electric field applied to the colored layer can be reduced. However, when the transparent protective film is thickened, film thickness unevenness during the formation of the transparent protective film tends to occur. Thereby, the hardness of a transparent protective film falls and the problem that a gap nonuniformity tends to generate | occur | produce arises. Further, when the film thickness of the transparent protective film is increased, there is a problem in that an image of an adjacent pixel is mixed when the screen is viewed obliquely. This problem becomes more conspicuous especially in a small-sized and high-resolution liquid crystal display device with a small pixel pitch.

  The present invention has been made in view of the above problems, and an object of the present invention is to provide a color filter that suppresses the occurrence of display defects due to a green pigment in a horizontal electric field drive type liquid crystal display device, and a horizontal electric field drive type using the same. The object is to provide a liquid crystal display device.

  As a result of intensive studies to solve the above-mentioned problems, the inventors have made the green colored layer thinner than the red and blue colored layers, and have a transparent protective layer on top of each colored layer. By forming the sum of the film thickness of each colored layer and the transparent protective film formed thereon, the effect of the lateral electric field on the green colored layer can be achieved without sacrificing other display characteristics. As a result, the present invention was completed. That is, the present invention is as follows.

The color filter of the present invention includes a transparent substrate, a black matrix layer, a colored layer colored in each of red, green, and blue, and a transparent protective film layer that covers the black matrix layer and the colored layer. A color filter, wherein the thickness of the red colored layer is T _R1 , the thickness of the green colored layer is T _G1 , the thickness of the blue colored layer is T _B1 , and the thickness of the transparent protective film provided on the red colored layer T _R2 , T _{G2 is} the thickness of the transparent protective film provided on the green colored layer, and T _B2 is the thickness of the transparent protective film provided on the blue colored layer, the following formula (1) and Satisfy (2).

  With this configuration, the green colored layer can be suppressed from directly affecting the lateral electric field.

  In the color filter, a photo spacer may be formed on the red colored layer and / or the blue colored layer.

  A lateral electric field drive type liquid crystal display device using the color filter may be used.

  In the color filter of the present invention, the green colored layer is made thinner than the red and blue colored layers, and a transparent protective layer is formed on each colored layer. The sum of the thickness of the transparent protective film is made substantially the same. As a result, it is possible to provide a color filter in which the occurrence of display defects due to the green pigment is suppressed and a horizontal electric field drive type liquid crystal display device using the color filter.

  Hereinafter, the color filter of the present invention will be described in detail with reference to the drawings.

[Color filter]
FIG. 1 is a schematic diagram illustrating the configuration of the color filter of the present invention. As shown in FIG. 1, the color filter 10 of the present invention includes a transparent substrate 11, a black matrix layer 12, a colored layer 13 colored in red, green, and blue, and the black matrix layer 12. And a transparent protective film layer 14 covering the colored layer 13.

As shown in FIG. 1, the color filter 10 of the present invention has a red colored layer 13R having a film thickness T _R1 , a green colored layer 13B having a film thickness T _G1 , and a blue colored layer 13B having a film thickness T _B1 . The thickness of the transparent protective film provided on the layer 13R is T _R2 , the thickness of the transparent protective film provided on the green colored layer 13G is T _G2 , and the transparent protective film provided on the blue colored layer 13B When the thickness is _TB2 , the following formulas (1) and (2) are satisfied.

  In addition, the said film thickness says the thickness in the orthogonal | vertical direction of the transparent substrate 10 plane. Even if it is not the color filter of the present invention, the relationship of the film thickness may be established in some pixel regions of the color filter in production. On the other hand, the color filter of the present invention is characterized in that the above film thickness relationship is established in all pixel regions of the color filter. The film thickness can be measured, for example, using a known measuring instrument such as a surface step meter or a scanning electron microscope (SEM).

The difference in film thickness between the red colored layer 13R, the blue colored layer 13B, and the green colored layer 13G is preferably 0.1 μm or more, and more preferably 0.15 μm or more. That is, it is preferable to satisfy the following formula (3). The upper limit of the following formula (3) is 0.5 μm or less, preferably 0.4 μm or less. If there is a difference in film thickness beyond this, the sum of the film thicknesses of the colored layers and the transparent protective film formed thereon cannot be made substantially the same.

  In the present invention, the thickness of the green colored layer is reduced. However, a liquid crystal display device with an improved NTSC ratio can be provided by adjusting the amount of pigment to be contained in the colored layer.

If there is a difference in film thickness between the respective colored layers of red, green, and blue, the difference in level causes a liquid crystal alignment defect, resulting in a display defect such as contrast. For this reason, in this invention, the transparent protective film 14 is provided on the upper part of each colored layer 13, and the sum of the film thickness of each colored layer 13 and the transparent conductive film 14, ie, the film thickness of a red colored layer: _TR1 + red coloring The film thickness of the transparent protective film provided on the layer: _TR2 , the film thickness of the green colored layer: _TG1 + the film thickness of the transparent protective film provided on the green colored layer: _TG2, and the blue colored layer Film thickness: T _B1 + Transparent protective film provided on the blue colored layer: T _B2 is substantially the same film thickness. Thereby, the difference between colors by the difference in the film thickness of a colored layer can be reduced. The sum of the film thickness of each colored layer and the transparent conductive film may be substantially the same, and is preferably 0.1 μm or less. That is, it is preferable to satisfy all three formulas of the following formula (4).

  Thus, in this invention, the film thickness of the transparent protective film provided in the upper part of a colored layer is not thickened uniformly. As a result, it is possible to suppress the occurrence of film thickness unevenness when forming the transparent protective film. Therefore, occurrence of gap unevenness can be effectively suppressed. When the transparent protective film is thickened and the screen is viewed obliquely, there is no problem that the image of the adjacent pixel is mixed.

[Liquid Crystal Display]
FIG. 2 is a cross-sectional view showing a conceptual configuration of a horizontal electric field drive type liquid crystal display device using the color filter of the present invention. As shown in FIG. 2, the liquid crystal display device 1 includes a liquid crystal layer 4 in which a color filter substrate 2 and an electrode substrate 3 are opposed to each other at a predetermined interval, and liquid crystal molecules 6 are sandwiched between the substrates.

  The color filter substrate 2 includes a transparent substrate 14, a black matrix 12 formed so as to partition a pixel region on one surface of the substrate, a red colored layer 13R and a green colored layer 13G formed in each pixel region. The colored layer 13 composed of the blue colored layer 13B and the transparent protective film 14 covering these are provided. An alignment film 15 is provided on the transparent protective film 14. A polarizing plate (not shown) is provided on the other surface of the color filter substrate.

  The electrode substrate 3 includes a transparent substrate 21, a common electrode 22 formed in a predetermined pattern on the substrate, a scanning wiring (not shown), and a pixel electrode formed in a predetermined pattern via the common electrode 22 and the insulating layer 24. 23, a signal wiring (not shown) and a protective film 25 covering these are provided. An alignment film 26 is provided on the protective film 25.

  As shown in FIG. 2, in the horizontal electric field drive type liquid crystal display device 1 using the color filter of the present invention, the thickness of the green colored layer 13G is smaller than the thickness of the red colored layer 13R and the blue colored layer 13B. Yes. With this configuration, the distance between the green colored layer 13G and the pixel electrode 23 can be increased. Thereby, the horizontal electric field 5 does not directly reach the green colored layer 13G. As a result, a lateral electric field drive type liquid crystal display device capable of reducing the influence of the lateral electric field 5 on the green colored layer 13G without sacrificing other display characteristics is provided. In addition, by forming the transparent protective film 14 with high flatness, it is possible to prevent deterioration in display characteristics such as contrast reduction that may occur due to a step between pixels.

  Further, in the lateral electric field drive type liquid crystal display device 1 using the color filter of the present invention, it is preferable that the photo spacer is formed on a pixel other than the green pixel having a thick transparent protective film (on the red colored layer and / or the blue colored layer). When manufacturing a liquid crystal display device, there is a step of applying pressure to the color filter substrate 2 and the electrode substrate 3. At this time, the photo spacer is uniformly crushed in the plane. As described above, in the present invention, the green colored layer is thinner than the red colored layer and the blue colored layer. On the other hand, the transparent protective film is thicker than the transparent protective film that covers the green colored layer. Therefore, (1) on the entire red, green and blue colored layers, (2) on the two colored layers of red and green, (3) on the two colored layers of blue and green, When the photo spacer is formed, the transparent protective film covering the green colored layer is thick, so that it is easily crushed and it is difficult to obtain a uniform cell gap. Therefore, it is possible to increase a margin for occurrence of gap unevenness by forming the photo spacer other than the green pixel having a thick transparent protective film thickness.

  The color filter of the present invention can be manufactured as follows.

[Production method]
In the color filter of the present invention, a black matrix layer is provided on a transparent substrate, and further, each colored layer composed of three primary colors of red, blue, and green is applied and patterned on the opening and part of the black matrix. Then, a transparent protective film is applied and dried. Thereafter, a spacer or the like may be formed if necessary.

(Transparent substrate)
The transparent substrate used in the present invention is not particularly limited, and a known material used as a transparent substrate can be used. Specific examples include inorganic glass such as quartz glass, borosilicate glass, aluminosilicate glass, soda lime glass whose surface is silica-coated, and organic plastic films or sheets. These transparent substrates may be formed with a transparent electrode such as ITO on the back surface for the purpose of preventing defects caused by static electricity.

(Black matrix layer)
The black matrix layer used in the present invention is composed of a resin black matrix in which a light shielding agent is dispersed in a resin. Moreover, it is not restricted to this, You may use metal thin films, such as chromium and chromium oxide.

  The resin used for the resin black matrix is not particularly limited, but photosensitive and non-photosensitive materials such as epoxy resins, acrylic resins, urethane resins, polyester resins, polyimide resins, polyolefin resins, and polyvinyl alcohol resins. Is preferably used.

  As the black matrix light-shielding agent, a mixture of red, blue, and green pigments can be used in addition to metal oxide powder such as carbon black, titanium oxide, and iron tetroxide, metal sulfide powder, and metal powder.

  The resin black matrix is manufactured by applying a black paste of resin in which a light-shielding agent is dispersed on a transparent substrate and drying, followed by patterning.

  As a method for applying the black paste, a dipping method, a roll coater method, a spinner method, a die coating method, a method using a wire bar, and the like are preferably used. Thereafter, heat drying (prebaking) using an oven or a hot plate is performed. Do. Although prebaking temperature changes with resin to be used, a solvent, and paste application amount, it is preferable to heat at 60-200 degreeC normally for 1 to 60 minutes.

  When the resin used for the black paste is a non-photosensitive resin, a positive type photoresist film is formed on the obtained black paste film, and then exposure and development are performed. When the resin used for the black paste is a photosensitive resin, exposure or development is performed as it is or after an oxygen blocking layer is formed. Thereafter, if necessary, the positive photoresist or the oxygen blocking film is peeled off and then dried again by heating (post-baking). The post-baking temperature varies depending on the resin, solvent, and film thickness to be used, but it is generally heated at 150 to 300 ° C. for 1 to 60 minutes.

  The film thickness of the resin black matrix is preferably 0.5 to 2.0 μm, more preferably 0.8 to 1.5 μm. When the film thickness is 0.5 μm or less, sufficient light shielding properties cannot be obtained, which is not preferable. On the other hand, when the film thickness is thicker than 2.0 μm, the light-shielding property can be secured, but the surface flatness of the color filter is sacrificed and a step is likely to occur. If a step in the pixel occurs, the display quality deteriorates due to light leakage, afterimage, and gap unevenness due to poor alignment of the liquid crystal, which is not preferable.

(Colored layer)
The resin black matrix is usually provided with openings of (20 to 200) μm × (20 to 200) μm according to the resolution and size of the liquid crystal display device. A plurality of three primary color layers are formed so as to cover at least the opening. That is, one opening is covered with any one of the three primary colors. A plurality of colored layers of each color are arranged.

  The colored layer constituting the color filter includes at least three primary colors. In general, color display is performed by an additive color method, and three primary colors of red (R), green (G), and blue (B) are selected. For the colored layers forming these three primary colors, a resin colored with a colorant is used.

  As the colorant used in the colored layer, organic pigments, inorganic pigments, dyes, and the like can be suitably used, and various additives such as ultraviolet absorbers, dispersants, and leveling agents may be added. As the organic pigment, phthalocyanine, azylate, condensed azo, quinacridone, anthraquinone, perylene, and perinone are preferably used.

  The resin used for the colored layer is not particularly limited, but photosensitive and non-photosensitive materials such as epoxy resin, acrylic resin, urethane resin, polyester resin, polyimide resin, polyolefin resin, and polyvinyl alcohol resin. Are preferably used, and it is preferable to disperse or dissolve the colorant in these resins for coloring.

  As a method for forming the colored layer, patterning is performed after a colored paste, which is a resin in which a colorant is dispersed or dissolved, is applied and dried on a substrate on which a resin black matrix is formed.

  The colored paste is obtained by mixing a resin and a colorant in a solvent and then dispersing the mixture in a disperser such as a triple roll, sand grinder, ball mill, or nanomill. The colorant may be washed with warm water or the like before dispersion, or may be purified by ion exchange treatment or the like after dispersion.

  As a method for applying the colored paste, as in the case of the black paste, a dip method, a roll coater method, a spinner method, a die coating method, a method using a wire bar, etc. are preferably used, and then an oven or a hot plate is used. Heat drying (pre-baking). Although prebaking temperature changes with resin to be used, a solvent, and paste application amount, it is preferable to heat at 60-200 degreeC normally for 1 to 60 minutes.

  From the first color coating film formed on the substrate on which the black matrix is formed as described above, unnecessary portions are removed by a photolithographic method to obtain a first colored layer. When the resin of the colored paste is a non-photosensitive resin, exposure and development are performed after forming a positive photoresist film thereon. When the resin of the colored paste is a photosensitive resin, exposure or development is performed as it is or after forming an oxygen blocking layer. Thereafter, if necessary, the positive photoresist or the oxygen blocking film is peeled off and then dried again by heating (post-baking). The post-baking temperature varies depending on the resin, solvent, and film thickness to be used, but it is generally heated at 150 to 300 ° C. for 1 to 60 minutes. Through the above process, a colored layer of the first color is formed on the substrate on which the black matrix is formed.

  The same operation is repeated for the second color and the third color to form a colored layer, and a colored layer composed of the three primary colors can be formed on the substrate on which the black matrix is formed.

  The film thicknesses of the three primary colors are not particularly limited as long as the green (G) film is formed thinner than the other two colors. Preferably they are 0.5 micrometer-4 micrometers, More preferably, they are 1.5 micrometers-3 micrometers. If the thickness of the colored layer is smaller than 0.5 μm, it is necessary to increase the concentration of the pigment in the colored layer in order to obtain a wide color reproduction range of NTSC ratio of 60% or more. Occurrence of cracks due to. In addition, the inclination angle of the color filter surface on the black matrix edge is increased, which tends to cause alignment failure. On the other hand, when the thickness of the colored layer exceeds 4 μm, it becomes difficult to uniformly apply or process the colored layer, and a residual film / residue is generated after development.

(Transparent protective film)
After forming the colored layer, a transparent protective film is formed.

  Resin used for the transparent protective film is not particularly limited, but photosensitive and non-photosensitive such as epoxy resin, acrylic resin, urethane resin, polyester resin, polyimide resin, polyolefin resin, polyvinyl alcohol resin, etc. Materials are preferably used.

  The transparent protective film is obtained by dissolving a resin in a solvent and applying and drying. As a method for applying the transparent protective film, as in the case of the black paste and the colored paste, a dipping method, a roll coater method, a spinner method, a die coating method, a method using a wire bar, and the like are preferably used. Heat drying using a hot plate. At this time, for the purpose of improving flatness, vacuum drying and preheating drying (prebaking) may be performed as necessary. In the case where a photosensitive resin is used as the transparent protective film, the solvent is removed by prebaking, and then exposure, photocuring, and heat drying are performed. Although prebaking temperature changes with resin to be used, a solvent, and application quantity, it is preferable to heat at 60-200 degreeC normally for 1 to 60 minutes. Moreover, although the conditions at the time of heat-drying differ with resin to be used, a solvent, and a film thickness, it is common to heat at 200-300 degreeC normally for 1 to 60 minutes.

  The thickness of the transparent protective film is preferably 0.5 to 3.0 μm. A thicker layer is more effective for improving the flatness, but if it exceeds 3.0 μm, it is not preferable because gap unevenness is likely to occur due to deterioration of coating uniformity and hardness. . On the other hand, if it is thinner than 0.5 μm, sufficient flatness cannot be obtained, which is not preferable.

  The solvent used for the coating liquid of the transparent protective film is not particularly limited as long as it dissolves the resin of the transparent protective film. For example, ethylene glycol methyl ethyl ether, diethylene glycol dimethyl ether, propylene glycol monomethyl ether acetate, ethylene glycol monobutyl ether acetate Diethylene glycol monoethyl ether acetate, 3-methoxy-3-methyl-1-butanol, ethylene glycol butyl ether, ethylene glycol ethyl ether, diethylene glycol butyl ether, diethylene glycol ethyl ether, γ-butyl lactone, n-methyl-2-pyrrolidone and the like are preferably used. In particular, in order to achieve the present invention, the above-mentioned solvent having a low volatilization rate is preferably used for the purpose of flattening the level difference of the colored layer generated by thinning the green colored layer. More preferred are n-methyl-2-pyrrolidone and γ-butyllactone. Further, for the purpose of improving the coating property, a surfactant or the like may be added as appropriate.

  Thereafter, if necessary, protrusions used for spacers and the like may be formed on the transparent protective film.

  EXAMPLES Hereinafter, although this invention is demonstrated further in detail based on a preferable Example, the efficacy of this invention is not restrict | limited at all by the following Example.

  In the examples and comparative examples described below, the color filter and the color liquid crystal display device were prepared as follows. In addition, in the examples and comparative examples described below, in order to compare and evaluate the influence on the display, the formula of the color filter is unified and only the ratio of the pigment and the binder resin and the film thickness are changed. did.

(1) Preparation of resin black matrix A carbon black mill base having the following composition was dispersed at 7000 rpm for 30 minutes using a homogenizer, and glass beads were filtered to prepare a black paste.

Composition of carbon black mill base Carbon black (MA100, Mitsubishi Chemical) 4.6 parts Polyimide precursor solution 24.0 parts N-methyl-2-pyrrolidone 61.4 parts Glass beads 90.0 parts

The black paste was applied to a glass substrate (manufactured by Nippon Electric Glass, OA-10) with a curtain flow coater, and dried on a hot plate at 130 ° C. for 10 minutes to form a black resin coating film. A positive photoresist was applied with a curtain flow coater, prebaked on a hot plate at 100 ° C. for 10 minutes, and exposed to a mask by irradiating with 100 mJ / cm ² ultraviolet rays using an ultrahigh pressure mercury lamp. Thereafter, using a 2.25% tetramethylammonium hydroxide aqueous solution, development of the photoresist and etching of the resin coating solution were simultaneously performed to form a pattern. Thereafter, the resist was peeled off with methyl cellosolve acetate and imidized by heating at 300 ° C. for 10 minutes on a hot plate to form a black matrix layer. The produced black matrix had a film thickness of 1.15 μm and an optical density (OD value) of 3.5.

(2) Creation of colored layer Next, red, green, and blue colored layers were formed.

  Similar to the black paste, the colored paste was prepared by dispersing pigments such as red, green and blue in the polyimide precursor. The basic configuration of each colored layer used in this example and comparative example is as follows. What adjusted the ratio in order to obtain predetermined chromaticity and film thickness was used.

Red colored paste: red pigment C.I. I. Pigment Red 177: PR177
Red pigment C.I. I. Pigment Red 254: PR254
Polyimide precursor
Solvent (n-methyl-2-pyrrolidone, γ-butyrolactone)

Green coloring paste: Green pigment C.I. I. Pigment Green 36: PG36
Yellow pigment C.I. I. Pigment Yellow 138: PY138
Polyimide precursor
Solvent (n-methyl-2-pyrrolidone, γ-butyrolactone)

Blue colored paste: Blue pigment C.I. I. Pigment Blue 15: PB15
Purple pigment C.I. I. Pigment Violet 23: PV23
Polyimide precursor
Solvent (n-methyl-2-pyrrolidone, γ-butyrolactone)

A red paste was applied on a glass substrate on which a resin black matrix was formed with a curtain flow coater, and dried on a hot plate at 130 ° C. for 10 minutes to form a red resin coating film. Thereafter, a positive photoresist was applied with a slit coater, prebaked on a hot plate at 100 ° C. for 5 minutes, and exposed to a mask by irradiating with 100 mJ / cm ² ultraviolet rays using an ultrahigh pressure mercury lamp. Thereafter, using a 2.25% tetramethylammonium hydroxide aqueous solution, development of the photoresist and etching of the resin coating film were simultaneously performed to form a pattern. Thereafter, the resist was peeled off with methyl cellosolve acetate and imidized by heating on a hot plate at 300 ° C. for 10 minutes to form a red colored layer.

  Next, a green colored pattern was formed in the same manner on the substrate on which the red colored layer was formed, thereby forming a green colored layer. Further, a blue coloring pattern was similarly formed on the substrate on which the red and green layers were formed, and a red, green and blue coloring layer was formed on the black matrix.

(Examples 1-3, Comparative Examples 1-3)
Color filters of Examples 1 to 3 and Comparative Examples 1 to 3 having the compositions shown in Table 1 below were prepared. In addition, each unit of Table 1 means weight%.

Each example and comparative example has the following features.
Comparative Example 1: A color filter using a green pigment in which more than 50% of chlorine is replaced with bromine in a chlorine 16-substituted product of copper phthalocyanine.
Comparative Example 2: A color filter in which the bromination rate of the green pigment was reduced to 50% or less in Comparative Example 1.
Comparative Example 3: A color filter in which the concentration of the green pigment contained in the green layer in the comparative example 2 is lowered.
Example 1: A color filter in which the transparent protective film is uniformly thickened on each colored layer of Comparative Example 2.
Example 2: A color filter in which the transparent protective film is uniformly thickened on each colored layer of Comparative Example 3.
Example 3: A color filter in which the thickness of the green colored layer is reduced in Comparative Example 3 and the thickness of the transparent protective film on the green colored layer is reduced.

(3) Formation of transparent protective film and spacer (adjustment of curable resin solution for protective film)
After dissolving trimellitic anhydride in γ-butyrolactone in a four-necked flask equipped with a stirring motor, stirring blade and thermometer, γ-aminopropyltriethoxysilane (trade name: KBE-903, manufactured by Shin-Etsu Chemical Co., Ltd.) And heated at 120 ° C. for 2 hours to obtain a compound containing alkoxysilane and carboxylic acid in the same molecule. A bisphenol A type epoxy compound (trade name: Epicoat: 1001B80, manufactured by Yuka Shell Epoxy Co., Ltd.) and diethylene glycol dimethyl ether (trade name: manufactured by Hisolv MDM, manufactured by Toho Chemical Co., Ltd.) are added to the resulting solution, and the mixture is stirred at room temperature for 2 hours for transparent protection. A thermosetting resin solution composition for a film was obtained.

(Formation of transparent protective film on color filter)
A thermosetting solution composition for a transparent protective film was applied to the color filter with a curtain flow coater, dried with a vacuum dryer, and then post-baked with a hot plate at 280 ° C. for 10 minutes to form a transparent protective film.

(Formation of photo spacer)
Thereafter, spacer protrusions were formed on the transparent protective film. As a photospacer material, JSR Optoma NN810 made of a photosensitive acrylic resin coating solution was used. The spacer material was applied with a curtain flow coater in the same manner as the other materials. After drying with a vacuum dryer, prebaking was performed at 100 ° C. for 5 minutes on a hot plate, and then mask exposure was performed by irradiating with 180 mJ / cm ² ultraviolet rays using an ultrahigh pressure mercury lamp. Thereafter, the coating film was developed using a 0.3% tetramethylammonium hydroxide aqueous solution to form a pattern. Then, it heated at 240 degreeC with the hotplate for 10 minutes, and formed the photo spacer.

(4) Evaluation of color filter Various characteristics such as chromaticity and color film thickness of the color filter prepared as described above were evaluated.

(Measurement of color characteristics)
The color characteristics of the colored layer were measured using a microspectrophotometer MCPD-2000 (manufactured by Otsuka Electronics). In this example and comparative example, in order to reduce the influence of the difference in chromaticity on display, a color filter was prepared and measured so as to have the chromaticity described below. In Examples and Comparative Examples described below, unless otherwise specified, the following target chromaticity was within ± 2/1000.

Target chromaticity red x = 0.650, y = 0.322
Green x = 0.288, y = 0.593
Blue x = 0.141, y = 0.074
The color reproducibility range at this time is 71.97% of NTSC ratio.

(Measurement of film thickness)
The film thickness was measured with a surface level meter (DEKTAK, manufactured by Nippon Vacuum) and a cross-sectional SEM. The surface level meter measured the distance from the glass surface to the outermost layer of the color layer at the BM opening before forming the transparent protective film. As for the film thickness of the transparent protective film, the distance from the glass substrate surface was measured outside the pixel region of the color filter after the transparent protective film was formed. The film thickness of each pixel in each example and comparative example is shown in Table 2- (1).

Measurement with a cross-sectional SEM was performed after processing the transparent protective film. When this method is used, it can be disassembled after the panel is manufactured. In this measurement, the color filter substrate is cut, the fracture surface is observed with an SEM, and the thicknesses of the colored layer and the transparent protective film can be measured. The results measured by this method are shown in Table 2- (2). In Table 2, the unit of film thickness is μm.

(5) Fabrication of color liquid crystal display panel and evaluation of display characteristics An alignment film made of polyimide resin is applied to the surfaces of the color filter substrate of the above-described comparative example of the example and the TFT array substrate by a printing method. Baked at 250 ° C. for 10 minutes. The film thickness was 0.07 μm. Thereafter, both the substrates were rubbed, applied with a sealant, baked on a hot plate at 90 ° C. for 10 minutes, and each two substrates were stacked and baked at 160 ° C. for 90 minutes while being pressurized. After injecting the liquid crystal between the substrates, the liquid crystal injection hole was sealed using a UV curable resin. Next, the polarizing plate was attached to the two glass substrates of the cell to complete the cell.

(6) Evaluation of color liquid crystal display panel The characteristics of the completed liquid crystal display panel were evaluated as follows.

  The cell gap was measured with a cell gap measuring device (manufactured by Otsuka Electronics Co., Ltd., RETS-3000), and further turned on with a panel lighting device, and no unevenness due to gap unevenness could be confirmed.

  Next, a high temperature continuous driving test was performed in the chamber while maintaining the temperature at 50 ° C., and occurrence of display defects due to the pigment was examined. For the evaluation of the display, observation was performed while changing the gradation from white display to black display, and it was confirmed whether it changed after 48 hours, 96 hours, and 500 hours, respectively, compared with the initial display. The results of the above observation are shown in Table 3. The unit of the cell gap is μm.

(7) Consideration of results In Comparative Example 1 using a green pigment having a high bromine substitution ratio, it was confirmed that the white display turned red in high temperature continuous driving. As disclosed in Japanese Patent Application Laid-Open No. 2004-69744, in Comparative Example 2 using a green pigment with a reduced bromination ratio, an improvement was seen compared to Comparative Example 1, but the white display is still red with continuous driving. The phenomenon was confirmed. Further, as disclosed in Japanese Patent Application Laid-Open No. 2003-315780, in Comparative Example 3 in which the concentration of the green pigment was lowered, the phenomenon that the white display becomes red was reduced, but the problem still remains. I understood.

  Example 1 in which the thickness of the transparent protective film was increased using the substrate prepared in the same manner as in Comparative Example 2 up to the colored layer, and the transparent protective film was formed in the same manner as in Comparative Example 3 up to the colored layer. In Example 2 where the thickness was increased, the phenomenon that the white display turned red was significantly improved. However, there was also a phenomenon that the uniformity of the gap slightly deteriorated due to the thick transparent protective film. On the other hand, the thickness of the green colored layer is made thinner than the thickness of the other colored layers, and the thickness of the transparent protective film on the green colored layer is made thicker than the transparent protective film on the other colored layers. In Example 3, the gap unevenness was improved, and the phenomenon that the white display became red was improved.

Example 4
Therefore, in order to make only the transparent protective film on the green colored layer thick, the color filter of Example 4 in which the green film thickness is made thinner than the other two colors and the transparent protective film having excellent planarization ability is formed. A color liquid crystal display device was produced. In Example 4, a color filter and a color liquid crystal display device were manufactured by using the same material as in Example 3 and changing only the green color film thickness in the same manner as described above.

The thickness of the green colored layer is 2.40 μm (standard 1), 2.30 μm (standard 2) (= Comparative Example 3), 2.20 μm (standard 3), 2.15 μm (standard 4), 2.10 μm ( Standard 5) and 2.05 μm (standard 6) were prepared. After the cell gap measurement of the completed color liquid crystal display device and the appearance inspection with the lighting device were performed in the same manner as in Example 3, a high-temperature continuous drive test was performed in a chamber maintained at 50 ° C. In the same manner as in Examples, the occurrence of display defects due to pigments was examined. In the initial state, the contrast was also measured. The evaluation results are shown in Table 4. Table 4 (1) shows the measurement results of the thicknesses of the colored layer and the protective film at each level. The unit is μm. Table 4 (2) shows the results of evaluating the characteristics of the color liquid crystal panels at each level.

  In all levels, no gap unevenness occurred in the initial state. The level of contrast decreased when the green film thickness was reduced (for example, level 6). This is thought to be due to non-uniform rubbing due to an increase in the level difference from other colored layers.

After evaluating these initial characteristics, high temperature continuous driving was performed. From levels 1 to 3 in which the film thickness of the green color layer is changed by fixing the film thickness of the red color layer and the blue color layer, “red unevenness” occurs early in order of increasing the film thickness of the green color layer, It was confirmed that it is more effective to reduce the green film thickness for “red unevenness”. On the other hand, it can be seen that “red unevenness” did not occur at levels 4 to 6 where the thickness of the green colored layer was thinner than the thickness of the red and blue colored layers.

FIG. 1 is a schematic diagram illustrating the configuration of the color filter of the present invention. FIG. 2 is a cross-sectional view showing a conceptual configuration of a horizontal electric field drive type liquid crystal display device using the color filter of the present invention. FIG. 3 is a cross-sectional view showing a conceptual configuration of a conventional lateral electric field drive type liquid crystal display device.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Liquid crystal display device 2 Color filter substrate 3 Electrode substrate 4 Liquid crystal layer 5 Horizontal electric field 6 Liquid crystal molecule 10 Color filter 11 Transparent substrate 12 Black matrix layer 13 Colored layer 14 Transparent protective film 15 Orientation film 21 Transparent substrate 22 Common electrode 23 Pixel electrode 24 Insulating layer 25 Protective film 26 Alignment film 100 Liquid crystal display device 110 First transparent substrate 111 Common electrode 112 Pixel electrode 113 Interlayer insulating film 114 Protective film 115 Alignment film 120 Second transparent substrate 121 Color filter 122 Black matrix 123 Colored layer 124 Transparent protective film 130 Liquid crystal sandwich layer 131 Lateral electric field 132 Liquid crystal molecules

Claims (3)

A transparent substrate;
A black matrix layer;
Colored layers colored in red, green and blue,
A color filter having the black matrix layer and a transparent protective film layer covering the colored layer,
The film thickness of the red colored layer is T _R1 , the film thickness of the green colored layer is T _G1 , the film thickness of the blue colored layer is T _B1 , the film thickness of the transparent protective film provided on the red colored layer is T _R2 , green color the thickness of the transparent protective film provided on the layer T _G2, satisfies the thickness of the transparent protective film provided on the blue colored layer when the T _B2, the following formula (1) and (2) , Color filter.

  The color filter according to claim 1, wherein a photo spacer is formed on the red colored layer and / or the blue colored layer. A lateral electric field drive type liquid crystal display device using the color filter according to claim 1.

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