JP2017134426A - Color filter and liquid crystal display device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a color filter and a liquid crystal display device which excel in oblique visibility.SOLUTION: Provided is a color filter comprising, on one surface of the transparent substrate, a black matrix layer, a plurality of colored pixel layers, an overcoat layer on the upper faces thereof, and a shading layer, the color filter being characterized in that the overcoat layer has a wedge-shaped groove on an upper extension of the black matrix layer and the shading layer exists in the wedge-shaped groove, that the color filter comprises, on one surface of a transparent substrate, a plurality of colored pixel layers, an overcoat layer on the top faces thereof, and a shading layer, and that the overcoat layer has a wedge-shaped groove on the upper extension of the boundary of two adjacent colored pixels, and the shading layer exists in the wedge-shaped groove.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a color filter for a liquid crystal display device and a liquid crystal display device.

  In general, a color filter 10 used in a color display panel of a color liquid crystal display device has a black matrix layer 2 on one surface of a transparent substrate 1 such as glass or plastic film, as shown in FIG. The colored pixel layer 3 and the overcoat layer 4 are formed.

  The colored pixel layer 3 is, for example, a pixel pattern in a matrix shape such as a stripe shape, a square dot shape, or a polygonal dot shape, and the colored layer is formed as a red, green, or blue colored layer, and the red, green, It has a blue filter function. Further, the pixel boundaries of the respective colored pixel layers 3 are surrounded by the black matrix layer 2.

  On the other hand, the black matrix layer 2 has a light shielding property, determines the position of the colored pixel layer 3, makes the size uniform, and emits undesired light when used in a liquid crystal display device. It has a function of shielding and making the image of the liquid crystal display device a uniform image with no unevenness and with improved contrast.

  The overcoat layer 4 has a function of preventing quality deterioration of the liquid crystal display device by preventing the transition of various compositions such as pigments and resins constituting the colored layer 3 to the liquid crystal layer. Further, the color filter 10 has a function of ensuring flatness and enabling stable incorporation into the liquid crystal display device.

  The formation method of the black matrix layer 5 is generally roughly classified into a dry thin film method using a vapor phase method and a wet thin film method using a photosensitive resin composition.

  As the method for forming the black matrix layer 2 by the dry thin film method, for example, a metal or a metal compound such as chromium or chromium oxide is formed using a dry thin film forming apparatus such as sputtering. Next, for example, a positive type photoresist is applied onto the thin film thus formed, and after mask exposure, development is performed to form an etching resist pattern. Then, the black matrix layer 2 is formed by etching the exposed portion of the metal thin film and further peeling the etching resist pattern.

  On the other hand, the formation method of the black matrix layer 2 by the wet thin film method using the photosensitive resin composition is, for example, by applying a black photosensitive resin composition, and then performing mask exposure, development, and washing steps, and then using a resin. A black matrix layer 2 is formed.

  Conventionally, the black matrix layer 2 (resin black matrix layer) made of resin is used for controlling internal reflection in a liquid crystal display device when a high-brightness backlight is used, or in a liquid crystal display device in an ISP (In Plane Switching) system. This was used when it was necessary to control the disturbance of the electric field at the time. However, recently, with the widespread use of large-sized TVs, resin black matrix layers have become the mainstream because of the tendency to respond to mass production and cost reduction, and to avoid using metals such as chromium in consideration of the environment. Yes.

The resin black matrix layer needs to be thicker because the light-shielding property is inferior at the same film thickness as compared to the black matrix layer made of a metal thin film layer. Therefore, the film thickness of the resin black matrix layer 2 is larger than the film thickness of the colored pixel layer.

  The colored pixel layer 3 is made of a colored photosensitive resin composition containing a colored pigment such as red, green, and blue and a photosensitive resin, and is formed in a void region of the resin black matrix layer 2.

  At this time, in the state where the colored pixel layer 3 is exposed, impurities enter the liquid crystal layer and cause deterioration in quality. Therefore, as a protective layer for preventing this, flatness including the colored layer is obtained. Therefore, an overcoat layer 4 is formed on the entire black matrix layer 2 and the colored pixel layer 3 (Patent Document 1).

  Generally, when a black matrix layer or a colored pixel layer is formed on a glass substrate, a fine uneven shape is formed on the outermost surface. Therefore, when the overcoat layer is laminated in this state, the outermost surface of the overcoat layer also has a fine concavo-convex shape due to the influence of the fine concavo-convex shape as a base. This fine uneven shape causes twisting and irregularity in the alignment of the liquid crystal molecules stacked on it, induces alignment defects in the liquid crystal molecules, or adversely affects the polarization state of light. It becomes a factor to reduce.

  As a method for solving the above problems, a polishing method for improving the flatness of the overcoat layer has been developed. For example, Patent Document 2 proposes a method using a polishing pad in which a polyurethane foam cloth polishing pad and a fine alumina abrasive are dispersed.

  However, in these methods, even if the flatness of the overcoat layer is obtained, the film thickness of the overcoat layer 4 is increased in order to cover the protruding region of the colored layer formed when the colored pixel layer 3 is formed. As a result, the black matrix layer 2 that separates each colored pixel 3 has insufficient light shielding properties, and the transmitted light 20 of the backlight cannot penetrate into the adjacent colored pixel layer to express an appropriate color. There is a possibility that a decrease in oblique visibility may occur.

JP 7-294720 A JP 2000-28819 A

  An object of the present invention is to provide a color filter provided in a color liquid crystal display device, which is excellent in oblique visibility and a liquid crystal display device.

The invention according to claim 1 of the present invention is a color filter comprising a black matrix layer, a plurality of colored pixel layers, an overcoat layer on the upper surface thereof, and a light shielding layer on one surface of the transparent substrate. And
The overcoat layer has a wedge-shaped groove on the upper extension of the black matrix layer;
The light shielding layer is a color filter in the wedge-shaped groove.

The invention according to claim 2 is a color filter comprising a plurality of colored pixel layers, an overcoat layer on the upper surface thereof, and a light shielding layer on one surface of the transparent substrate,
The overcoat layer has a wedge-shaped groove on the upper extension of the boundary between two adjacent colored pixels,
The light shielding layer is a color filter in the wedge-shaped groove.

  The invention according to claim 3 is the color filter according to claim 1 or 2, further comprising a photo spacer on the light shielding layer. The invention according to claim 4 is a liquid crystal display device comprising the color filter according to any one of claims 1 to 3.

  According to the first aspect of the present invention, the overcoat layer and the wedge-shaped groove adjacent to the overcoat layer are embedded on the black matrix layer and the colored pixel layer formed on one surface of the transparent substrate. Since the light shielding layer is formed in such a shape, a uniform cell gap can be obtained and a color filter excellent in oblique visibility can be obtained.

  The wedge-shaped groove has a local light intensity distribution difference by using a photomask having a slit line shape with a width of 1 to 6 μm in the step of forming the overcoat layer, and the overcoat layer has a wedge shape. Can be formed. Then, a light shielding layer can be formed by embedding a light shielding resin composition in the groove, and more excellent oblique visibility can be obtained in addition to the underlying black matrix layer.

  According to the second aspect of the present invention, the wedge-shaped light shielding layer is embedded in the overcoat layer and the overcoat layer on the colored pixel layer formed on one surface of the transparent substrate without the black matrix layer. Therefore, a uniform cell gap can be obtained, and the manufacturing process of a color filter excellent in oblique visibility can be shortened.

  Since the wedge-shaped light-shielding layer is formed in a shape embedded in the overcoat layer, the overcoat layer and the light-shielding layer are the same flat surface, the cell gap in the subsequent process is uniform, and a high-quality image is obtained. The color filter which can form can be provided. In addition, since a light shielding layer having a height higher than that of the conventional one is formed, it is possible to provide characteristics excellent in oblique visibility.

1 is a cross-sectional view of an embodiment of a color filter of the present invention. A sectional view of one embodiment of a conventional color filter is shown. The manufacturing flow of one Embodiment of the color filter of this invention is shown.

  Hereinafter, a color filter and a liquid crystal display device of the present invention will be described in detail with reference to the drawings.

  As shown in FIG. 1A, an embodiment of a color filter according to the present invention has a black matrix layer 2 and a plurality of colored pixel layers 3, for example, a red pixel layer of the first color (see FIG. 1A). R), a green pixel layer (G) of the second color, and a blue pixel layer (B) of the third color are formed.

  Then, an overcoat layer 4 and a wedge-shaped light shielding layer 5 for protecting the black matrix layer 2 and the colored pixel layer 3 are formed at predetermined positions on the black matrix layer 2 and the colored pixel layer 3, and further at predetermined positions thereon. A color filter 10 in which a photo spacer 6 is formed.

  Further, the color filter according to the present invention can be implemented in another embodiment as shown in FIG. Specifically, a plurality of colored pixel layers 3 are formed on one surface of the transparent substrate, an overcoat layer 4 is formed on the upper surface thereof, and both regions of adjacent colored pixel layers 3 are overlapped. This is a color filter 10 in which a wedge-shaped light-shielding layer 5 is formed on the extension of the position.

  Hereinafter, the manufacturing method of the color filter 10 according to the present invention will be described in detail with reference to FIG.

  FIG. 3 shows a manufacturing flow of FIG. 1A which is an embodiment of the color filter of the present invention.

  As shown in FIG. 3A, first, a black matrix layer 2 (hereinafter referred to as a BM layer) is formed on one surface of the transparent substrate 1. A method for forming the BM layer 2 is not particularly limited, but a photolithography method (hereinafter referred to as a photolithography method) is preferable.

  Next, as shown in FIG. 3B, a red photosensitive resin composition for forming the red pixel layer (R) is applied, dried, mask exposure, development, washing, drying, and the like by photolithography. Then, a red pixel layer (R) is formed. Thereafter, the same method is sequentially repeated to form the green pixel layer (G) and the blue pixel layer (B), thereby completing the formation of the colored pixel layer 3.

  Next, as shown in FIG. 3C, a transparent photosensitive resin composition is applied to the entire surface of the colored pixel layer 3 and dried to laminate the overcoat layer 4.

  Next, as shown in FIG.3 (d), it exposed using the photomask 30 which has a slit line shape of width | variety 1-6 micrometers, and the said BM layer was formed through development, washing | cleaning, and a drying process after that. A wedge-shaped groove shown in FIG. 3 (e) is formed on the upper extension of the position.

  Since the photomask 30 used in this step has a slit line shape with a width of 1 to 6 μm, a local light intensity distribution difference is generated, and a wedge-shaped groove can be formed in the overcoat layer.

  Next, a light-sensitive photosensitive resin composition is embedded in the wedge-shaped groove formed as described above, and then cured by irradiation with ultraviolet rays to form a light-shielding layer 5 shown in FIG.

  The transparent substrate 1 according to the present invention is not particularly limited as long as it has transparency, heat resistance, chemical stability, physical stability, and the like. For example, a plastic substrate represented by a general glass plate or preethylene terephthalate (PET) can be used.

  Moreover, the BM layer 2 is obtained by forming by a photolithography method using a black photosensitive resin composition. The black photosensitive resin composition generally comprises a black pigment, a photosensitive resin, a photopolymerization initiator, an additive, a solvent, and the like, and is not particularly limited.

  The colored pixel layer 3 is preferably formed by a photolithography method using a colored photosensitive resin composition. The colored photosensitive resin composition is generally composed of colored pigments such as red, green, and blue, a photosensitive resin, a photopolymerization initiator, an additive, and a solvent, and is not particularly limited.

  The overcoat layer 4 is for preventing the liquid crystal layer and the colored pixel layer from being in direct contact and for imparting flatness of the color filter 10. Generally, the overcoat layer 4 is a transparent photosensitive resin, It consists of a photopolymerization initiator, an additive, a solvent and the like, and is not particularly limited.

  A photomask 30 used as means for forming a wedge-shaped groove in the overcoat layer 4 has a slit line shape with a width of 1 to 6 μm. When the slit width is in the range of 1 to 6 μm, a local light intensity distribution difference can be generated. As a result, a wedge-shaped unexposed area is formed, and a groove can be formed in the subsequent development process. If the slit width is less than 1 μm, light transmission becomes difficult, and if it exceeds 6 μm, a local difference in light intensity distribution cannot be generated.

  As the photosensitive resin composition for forming the light shielding layer 5, a black photosensitive resin composition for forming the BM layer can be used. Moreover, the photosensitive resin composition which has another light-shielding property may be sufficient, and it does not specifically limit.

  Hereinafter, the color filter and the liquid crystal display device of the present invention will be described more specifically with reference to examples.

<Example 1>
The following black photosensitive resin composition is applied on one surface of a glass substrate so that the film thickness after drying becomes 3 μm, and then exposed using a photomask for forming a BM layer (line width 20 μm). , Development, washing and drying to form a BM layer.

(Black photosensitive resin composition)
Carbon black dispersion (manufactured by Mikuni Dye: EX-2806) 25 parts by weight Resin (manufactured by Nippon Steel Chemical Co., Ltd .: V259-ME) 7 parts by weight Monomer (manufactured by Nippon Kayaku Co., Ltd .: DPHA) 1 part by weight Photopolymerization initiator ( Irgacure 379) 1 part by weight Solvent (propylene glycol monomethyl acetate) 30 parts by weight Solvent (ethyl-3-ethoxypropionate) 36 parts by weight Next, the entire surface on the side where the BM layer is formed is made of a photosensitive resin. The following red photosensitive resin composition was applied, exposed using a photomask for forming a red pixel layer, and then developed, washed, and dried to form a red pixel layer having a thickness of 1.5 μm.

(Red photosensitive resin composition)
C. 20 wt% cyclohexanone solution of acrylic resin 40 parts by weight Dipentaerythritol pentaacrylate 10 parts by weight C.I. I. Pigment Red 177 7 parts by weight Photopolymerization initiator 2 parts by weight Pigment dispersant 2 parts by weight 2-methoxyethanol 39 parts by weight

  In the same manner as the formation of the red pixel layer, a green pixel layer and a blue pixel layer having a thickness of 1.5 μm are sequentially formed using a green photosensitive resin composition and a blue photosensitive resin composition having the following compositions. Formed.

(Green photosensitive resin composition)
C. 20 wt% cyclohexanone solution of acrylic resin 40 parts by weight Dipentaerythritol pentaacrylate 10 parts by weight C.I. I. Pigment Green 36 8 parts by weight Photopolymerization initiator 2 parts by weight Pigment dispersant 2 parts by weight 2-methoxyethanol 38 parts by weight

(Blue photosensitive resin composition)
C. 20 wt% cyclohexanone solution of acrylic resin 40 parts by weight Dipentaerythritol pentaacrylate 10 parts by weight C.I. I. Pigment Blue 15: 6 6 parts by weight Photopolymerization initiator 2 parts by weight Pigment dispersant 2 parts by weight 2-methoxyethanol 40 parts by weight

  Next, on the entire surface of the glass substrate on which the red, green, and blue colored layers are formed, the transparent photosensitive resin composition for forming the overcoat layer having the following composition is dried to have a thickness of 2.0 μm. Applied.

(Transparent photosensitive resin composition for overcoat layer formation)
20 wt% cyclohexanone solution of acrylic resin 40 parts by weight Dipentaerythritol pentaacrylate 10 parts by weight Photopolymerization initiator 2 parts by weight 2-methoxyethanol 48 parts by weight

  Next, an overcoat layer was formed through exposure, development, washing, and drying processes using a photomask having slit lines with a width of 3 μm. At the same time, a wedge-shaped groove was formed on the upper extension of the position where the BM layer was formed.

  Next, the BM layer forming composition was embedded in the wedge-shaped groove, and then cured by irradiating with ultraviolet rays to form a light shielding layer.

  A pattern was formed using a photosensitive resin composition for forming a photospacer, and then cured by irradiating with ultraviolet rays to prepare a color filter having a photospacer.

<Comparative Example 1>
A color filter was produced in the same manner as in Example 1 except that a photomask having a slit line with a width of 10 μm was used.

<Evaluation>
A liquid crystal display device was produced using the color filter obtained in Example 1 and Comparative Example 1, and image evaluation was performed visually.

<Comparison result>
The color filter having a wedge-shaped light shielding layer obtained in Example 1 showed excellent results in oblique visibility. This is presumed to be due to the effect of a deep wedge-shaped light shielding layer in addition to the conventional BM layer. On the other hand, in the color filter obtained in Comparative Example 1, the light shielding layer became a wide rectangle, the image display area was narrowed, and effective oblique visibility was not obtained.

  ADVANTAGE OF THE INVENTION According to this invention, the manufacturing method of the color filter which has the display quality excellent in diagonal visibility, the color filter produced using the same, and a liquid crystal display device provided with the same can be provided.

DESCRIPTION OF SYMBOLS 1 ... Transparent substrate 2 ... Black matrix layer 3 ... Colored pixel layer 4 ... Overcoat layer 5 ... Shading layer 6 ... Spacer 10 ... Color filter 20 ... Light source 30 ... Photomask

Claims (4)

On one surface of the transparent substrate, a color filter comprising a black matrix layer, a plurality of colored pixel layers, an overcoat layer on the upper surface thereof, and a light shielding layer,
The overcoat layer has a wedge-shaped groove on the upper extension of the black matrix layer;
The color filter according to claim 1, wherein the light shielding layer is in the wedge-shaped groove. On one surface of the transparent substrate, a color filter composed of a plurality of colored pixel layers, an overcoat layer on the upper surface thereof, and a light shielding layer,
The overcoat layer has a wedge-shaped groove on the upper extension of the boundary between two adjacent colored pixels,
The color filter according to claim 1, wherein the light shielding layer is in the wedge-shaped groove.   The color filter according to claim 1, further comprising a photo spacer on the light shielding layer.   A liquid crystal display device comprising the color filter according to claim 1.