JP5104201B2 - Color filter and manufacturing method thereof - Google Patents

Description

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

  In order to realize outdoor visibility, a transflective liquid crystal display device is used. The transflective liquid crystal display device has a transmissive region and a reflective region in one pixel (see, for example, Patent Document 1).

  A conventional example of a transflective liquid crystal display device will be described with reference to FIG. FIG. 3 is a schematic view of a cross section of a conventional transflective liquid crystal display device 100 in which elements such as electronic circuits and TFTs are omitted. The liquid crystal display device 100 is mainly formed by sequentially providing a color filter 101, a liquid crystal cell 108, a substrate 113, and a backlight unit 115.

  The color filter 101 is provided with a multi-gap layer 103 having a trapezoidal cross section on a transparent substrate 102 and a colored layer 107 coated thereon and patterned corresponding to the pixels. Further thereon, a transparent electrode 106 is provided. A black matrix 105 is provided between the colored layer 107 and the colored layer 107 of another color to improve the contrast. A transparent electrode 109 is provided on the transparent substrate 113 corresponding to the pixel, and a reflective electrode 111 is provided on a part of the transparent electrode 109. By applying a voltage between the transparent electrode 106, the transparent electrode 109, and the reflective electrode 111, a voltage is applied to the liquid crystal cell 108, and the orientation of the liquid crystal molecules 117 is controlled. A backlight unit 115 is provided on the back surface of the substrate 113. A polarizing plate 114 is provided between the backlight unit 115 and the substrate 113, and a polarizing plate 112 is provided on the substrate 102.

  The liquid crystal display device 100 includes a reflective region having the reflective electrode 111 and a transmissive region having no reflective electrode 111. In the transmissive region, light generated from the backlight unit 115 passes through the polarizing plate 114, the substrate 113, the transparent electrode 109, the liquid crystal cell 108, the transparent electrode 106, the colored layer 107, the substrate 102, and the polarizing plate 112, and the liquid crystal display device 100. To reach outside. In the reflective region, light incident from the outside of the liquid crystal display device 100 passes through the polarizing plate 112, the substrate 102, the multigap layer 103, the colored layer 107, the transparent electrode 106, and the liquid crystal cell 108 and is reflected by the reflective electrode 111. Then, the light passes through the liquid crystal cell 108, the transparent electrode 106, the colored layer 107, the multi-gap layer 103, the substrate 102, and the polarizing plate 112 and reaches the outside of the liquid crystal display device 100.

  In this way, by providing the reflective region and the transmissive region in one pixel, it is possible to observe the display by the reflective region in bright outdoors and the display by the transmissive region indoors, and the transflective liquid crystal display device can be used outdoors. Can be used indoors.

  In the reflection region, light passes through the colored layer 107 and the liquid crystal cell 108 twice. Therefore, the color reproduction range in the reflection region is made equal to that of the transmission type by making the thickness of the colored layer 107 and the liquid crystal cell 108 corresponding to the reflection region thinner than those in the transmission region. In particular, the liquid crystal cell is half the thickness of the transmission region (see, for example, Non-Patent Document 1).

JP 2004-102243 A Koichi Fujimori, 2 others, “High Transmission Advanced TFT-LCD Technology”, Sharp Technical Journal, Sharp Corporation, April 2003, Volume 85, p.34-37

  However, in the liquid crystal display device 100 shown in FIG. 3, the orientation of the liquid crystal molecules 117 in the liquid crystal cell 108 is greatly influenced by the shapes of the colored layer 107 and the transparent electrode 106. FIG. 4 is a diagram showing the color filter 101 and the liquid crystal segmentation 117. As shown in FIG. 4, the alignment of the liquid crystal molecules 117 is disturbed by the taper of the colored layer 107 and the transparent electrode 106. Therefore, there is an invalid area between the transmissive area and the reflective area of the color filter 101 that does not contribute to either transmissive or reflective display. In the invalid region, the alignment of the liquid crystal molecules 117 is disturbed, so that light leaks and the contrast of the liquid crystal display device 100 decreases.

  The present invention has been made in view of the above-described problems, and an object of the present invention is to provide a color filter that realizes a high-contrast liquid crystal display device free from light leakage.

In order to achieve the above-described object, a first invention provides a light-transmitting substrate, a multi-gap layer having an inverted trapezoidal cross section formed on the substrate, the substrate, and the multi-gap layer. A colored layer formed along the colored layer, and a protective layer having a substantially U-shaped cross-section with an opening facing downward in the vicinity of the multi-gap layer. This is a characteristic color filter.

The second invention is a step (a) of forming a multi-gap layer having an inverted trapezoidal cross section on a light-transmitting substrate, and a step of forming a colored layer on the substrate and the multi-gap layer. (B) and a step (c) of forming a protective layer along the colored layer , and in the vicinity of the multi-gap layer, the cross-section of the protective layer has a substantially U-shape with the opening facing downward. A color filter manufacturing method having a cross-sectional shape . Further, in the step (a), it is preferable to overdevelop or overexpose.

  According to the present invention, it is possible to provide a color filter that realizes a high-contrast liquid crystal display device free from light leakage.

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

The color filter 1 according to the first embodiment will be described.
FIG. 1 is a diagram showing a color filter 1 and liquid crystal molecules 5. The multi-gap layer 3 is formed on the substrate 9, and the colored layer 7 is formed thereon.

  The colored layer 7 has a transmissive region and a reflective region having a thickness smaller than that of the transmissive region. In the transmissive region, light passes through the colored layer 7 only once, but in the reflective region, light passes through the colored layer 7 twice. At this time, the thickness of the colored layer 7 in the reflection region is reduced and the color density is reduced so that the displayed color does not change in the reflection region and the transmission region.

  As the substrate 9, a substrate generally used for a color filter can be used. For example, inflexible transparent rigid materials such as borosilicate glass, aluminoborosilicate glass, alkali-free glass, quartz glass, synthetic quartz glass, soda lime glass, white sapphire, transparent resin film, optical resin film, etc. A transparent flexible material having the following flexibility can be used. As the flexible material, acrylic such as polymethyl methacrylate, polyamide, polyacetal, polybutylene terephthalate, polyethylene terephthalate, polyethylene naphthalate, triacetyl cellulose, syndiotactic polystyrene, polyphenylene sulfide, polyether ketone, polyether ether ketone, Examples include fluororesin, polyether nitrile, polycarbonate, modified polyphenylene ether, polycyclohexene, polynorbornene resin, polysulfone, polyethersulfone, polyarylate, polyamideimide, polyetherimide, thermoplastic polyimide, and the like. However, those made of general plastics can also be used. Among these, alkali-free glass is a material having a small coefficient of thermal expansion, and is excellent in dimensional stability and characteristics in high-temperature heat treatment.

  The colored layer 7 is a colored layer used for a color filter, and is a photosensitive resin containing a pigment. As the photosensitive resin, either a positive type or a negative type can be used. The positive resist material is not particularly limited, and examples thereof include a chemically amplified resist using a novolac resin as a base resin. The negative resist material is not particularly limited. For example, a chemically amplified resist based on a crosslinkable resin or a photocurable resist based on an acrylic resin, specifically polyvinylphenol, a crosslinker. And a chemically amplified resist containing an acid generator, an acrylic copolymer resin, a polyfunctional acrylate monomer, and an ultraviolet curable resist containing a photopolymerization initiator. In the present embodiment, a case where a negative photosensitive resin is used will be described.

  The multi-gap layer 3 is made of a photosensitive resin, and the same photosensitive resin as that constituting the colored layer 7 is used. The multi-gap layer 3 makes it possible to equalize the path of light passing through the liquid crystal cell in the transmissive region and the reflective region, and to make the phase difference value constant.

  The cross section of the multi-gap layer 3 has an inverted trapezoidal shape or an inverted tapered shape in which the length of the upper side not in contact with the substrate 9 is longer than the length of the lower side in contact with the substrate 9. Therefore, the colored layer 7 formed on the multi-gap layer 3 can have a rectangular cross section.

  A method for manufacturing the color filter 1 according to the first embodiment will be described. FIG. 2 is a diagram illustrating a manufacturing process of the color filter 1.

  First, as shown in FIG. 2A, a photosensitive resin is applied on the substrate 9 to form a transparent resin layer 19. Examples of the method for applying the photosensitive resin include spin coating, casting, dipping, bar coating, blade coating, roll coating, gravure coating, flexographic printing, spray coating, and die coating. .

  Next, as shown in FIG. 2A, exposure is performed using a mask 11 having a transparent portion 13 and a light shielding portion 15. The transparent portion 13 transmits light 17 and the light shielding portion 15 does not transmit light 17.

  The mask 11 has a light shielding film on a transparent substrate. A portion having no film on the substrate becomes the transparent portion 13, and a portion having the light shielding film on the substrate becomes the light shielding portion 15.

  As the transparent substrate used for the substrate, a substrate used for the substrate 9 can be used. Among them, synthetic quartz glass is usually used.

  The light-shielding film does not substantially transmit exposure light, and preferably has an average transmittance of 0.1% or less at the exposure wavelength. As such a light shielding film, a light shielding film generally used for a photomask can be used. For example, chromium, chromium oxide, chromium nitride, chromium oxynitride, molybdenum silicide, tantalum, aluminum, silicon, silicon oxide, silicon oxynitride And the like. Of these, chromium-based films such as chromium, chromium oxide, chromium nitride, and chromium oxynitride are preferably used. This is because such a chromium-based film has the most use record and is preferable in terms of cost and quality. This chromium-based film may be a single layer or may be a laminate of two or more layers.

  The film thickness of the light shielding film is not particularly limited, and for example, in the case of a chromium film, it can be about 50 nm to 150 nm.

  As a method for forming the light shielding film, for example, a physical vapor deposition method (PVD) such as a sputtering method, an ion plating method, or a vacuum vapor deposition method is used.

  Next, as shown in FIG. 2 (b), by using a negative photosensitive resin for the transparent resin layer 19, curing of the resin proceeds only in a portion corresponding to the transparent portion 13 of the transparent resin layer 19, Since the resin does not cure in the portion corresponding to the light shielding portion 15, the multi-gap layer 3 is formed in the portion corresponding to the transparent portion 13 during the development, and nothing is formed in the portion corresponding to the light shielding portion 15. Not.

  Unlike the conventional multi-gap layer 103 shown in FIG. 4, the multi-gap layer 3 according to the first embodiment has an inverted trapezoidal cross section. The multi-gap layer 3 is formed by lowering the prebake temperature, increasing the exposure amount, shortening the exposure gap, and lengthening the development time than the conditions for forming the multi-gap layer 103. Moreover, you may raise the exposure sensitivity of photosensitive resin. It is not always necessary to change all the conditions, but they may be changed as necessary.

  Next, as shown in FIG. 2C, a photosensitive resin containing a pigment is applied on the substrate 9 to form a colored layer 7, and the color filter 1 is manufactured. The colored layer 7 can be formed by the same method as the application of the transparent resin layer 19.

  According to the first embodiment, since the cross section of the multi-gap layer 3 has an inverted trapezoidal shape, the colored layer 7 coated thereon can be prevented from being tapered, and the cross section of the colored layer 7 can be prevented. Can be rectangular.

  Further, according to the first embodiment, the ineffective area existing in the color filter 101 according to the conventional example shown in FIG. This is because in the color filter 1, since the colored layer 7 does not have a tapered portion, the alignment of the liquid crystal molecules 5 in contact with the colored layer 7 is not disturbed.

  Further, the color filter 1 according to the first embodiment has the multi-gap layer 3 in the reflective region, like the color filter 101 in the conventional example, and the colored layer 7 in the reflective region is more than the colored layer 7 in the transmissive region. Therefore, a liquid crystal display device having high color reproducibility can be realized.

  If necessary, a protective layer made of a transparent resin may be formed on the colored layer 7. By forming the protective layer, there is no step between the colored layers, leading to an improvement in contrast of the liquid crystal display device. At this time, the reverse taper angle of the multi-gap layer 3 may be made steeper, and the cross section of the protective layer may be rectangular.

  Hereinafter, the present invention will be specifically described using examples and comparative examples. This will be described in more detail using examples.

  As the substrate, a glass substrate (Corning 1737 glass) having a size of 300 mm × 400 mm and a thickness of 0.7 mm was prepared. After this substrate was washed according to a conventional method, a chromium thin film (thickness: 1000 mm) was formed on the entire surface of one side of the substrate by sputtering. On this chromium thin film, a positive photosensitive resist (OFPR-8 manufactured by Tokyo Ohka Kogyo Co., Ltd.) was applied, and exposed and developed through a predetermined mask to form a resist pattern. Next, using this resist pattern as a mask, the chromium thin film was etched to form a black matrix having a line width of 20 μm and a pitch of 100 μm.

  Next, a negative photosensitive resin (polymer I) for a multi-gap layer, a negative photosensitive resin for a red pattern, a negative photosensitive resin for a green pattern, and a negative photosensitive resin for a blue pattern were prepared. .

<Polymer I>
・ Methyl methacrylate-styrene-acrylic acid copolymer 32 parts by weight ・ Epoxy resin: Epicoat 180s70 (Japan Epoxy Resin Co., Ltd.) 18 parts by weight ・ Dipentaerythritol pentaacrylate 42 parts by weight ・ Ilquagua 907 (Ciba Specialty Chemicals) 8 parts by weight) 300 parts by weight of propylene glycol monomethyl ether acetate

<Negative photosensitive resin for red pattern>
Red pigment (Ciba Specialty Chemicals Chromophthal Red A2B) 4.8 parts by weight Yellow pigment (BASF Pariotor Yellow D1819) 1.2 parts by weight Dispersant (Bicchemy Disperbic 161) 3 1.0 part by weight / monomer (SR399 manufactured by Sartomer) 4.0 parts by weight Polymer I 5.0 parts by weight initiator (Irgacure 907 manufactured by Ciba Specialty Chemicals) 1.4 parts by weight initiator (2, 2′-bis (o-chlorophenyl) -4,5,4 ′, 5′-tetraphenyl-1,2′-biimidazole) 0.6 part by weight / solvent (propylene glycol monomethyl ether acetate) 80.0 parts by weight

<Negative photosensitive resin for green pattern>
Green pigment (Avisia Monastral Green 9Y-C) 4.2 parts by weight Yellow pigment (BASF Pariotor Yellow D1819) 1.8 parts by weight Dispersant (Bicchemy Disperbic 161) 3.0 Parts by weight / monomer (SR399, manufactured by Sartomer) 4.0 parts by weight, polymer I 5.0 parts by weight, initiator (Irgacure 907, manufactured by Ciba Specialty Chemicals) 1.4 parts by weight, initiator (2,2 ′ -Bis (o-chlorophenyl) -4,5,4 ', 5'-tetraphenyl-1,2'-biimidazole) 0.6 parts by weight / solvent (propylene glycol monomethyl ether acetate) 80.0 parts by weight

<Negative photosensitive resin for blue pattern>
Blue pigment (BASF Heliogen Blue L6700F) 6.0 parts by weight Pigment derivative (Abyssia Solsperse 5000) 0.6 parts by weight Dispersant (Bic Chemie Dispersic 161) 2.4 parts by weight Monomer (SR399, manufactured by Sartomer) 4.0 parts by weight, Polymer I, 5.0 parts by weight, initiator (Irgacure 907, manufactured by Ciba Specialty Chemicals) 1.4 parts by weight, initiator (2,2'-bis (o -Chlorophenyl) -4,5,4 ', 5'-tetraphenyl-1,2'-biimidazole) 0.6 parts by weight / solvent (propylene glycol monomethyl ether acetate) 80.0 parts by weight

Subsequently, the polymer I was applied onto the glass substrate by a spin coating method so as to cover the black matrix, and pre-baked at 80 ° C. for 3 minutes to form a transparent resin layer. Then, it exposed with the exposure amount of 200 mJ / cm < ² > and the exposure gap of 100 micrometers through the photomask.

  Next, development was carried out for 90 seconds using a 0.05 wt% aqueous potassium hydroxide solution, followed by baking in an oven at 200 ° C. for 30 minutes to form a multi-gap layer having an inverted trapezoidal cross section.

Next, a negative photosensitive resin for a red pattern is applied to the multi-gap layer by spin coating, pre-baked at 100 ° C. for 3 minutes, and the exposure amount is 100 mJ / cm ² and the exposure gap is 150 μm through a photomask. And exposed. Next, development was carried out for 60 seconds using a 0.05 wt% potassium hydroxide aqueous solution, followed by baking in an oven at 200 ° C. for 30 minutes to form a red pattern.

  Next, the same applies to the negative photosensitive resin for the green pattern and the negative photosensitive resin for the blue pattern.

[Comparative example]
A color filter was produced in the same manner as in Example except that the multi-gap layer was formed as described below.
After application of polymer I, pre-baking was performed at 100 ° C. for 3 minutes, and exposure was performed through a photomask with an exposure amount of 100 mJ / cm ² and an exposure gap of 150 μm. Next, development was performed for 60 seconds using a 0.05 wt% aqueous potassium hydroxide solution to form a multi-gap layer.

[Evaluation]
When the cross-sectional shape of the colored layer was confirmed, the width of the invalid region was 12 μm in the comparative example, whereas it was 4 μm in the example, and the width of the invalid region was narrowed. Further, the contrast value of the liquid crystal display using these color filters is 1410 in the comparative example, and 2370 in the example, confirming the improvement in contrast.

  The preferred embodiments of the color filter according to the present invention have been described above with reference to the accompanying drawings, but the present invention is not limited to such examples. It will be apparent to those skilled in the art that various changes and modifications can be made within the scope of the technical idea disclosed in the present application, and these are naturally within the technical scope of the present invention. Understood.

1 is a diagram showing a color filter 1 and liquid crystal molecules 5 according to a first embodiment. The figure which shows the manufacturing process of the color filter 1 which concerns on 1st Embodiment. The figure which shows the liquid crystal display device 100 which concerns on a prior art example. The figure which shows the color filter 101 and liquid crystal molecule 117 which concern on a prior art example.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ......... Color filter 3 ......... Multi-gap layer 5 ......... Liquid crystal molecule 7 ......... Colored layer 9 ......... Substrate 11 ......... Mask 13 ......... Transparent part 15 ......... Light-shielding part 17 ... ... Light 19 ......... Transparent resin layer 100 ......... Liquid crystal display device 101 ......... Color filter 102 ......... Substrate 103 ......... Multi-gap layer 105 ......... Black matrix 106 ......... Transparent electrode 107 ......... Colored layer 108 ......... Liquid crystal cell 109 ......... Transparent electrode 111 ......... Reflective electrode 112 ......... Polarizing plate 113 ......... Substrate 114 ......... Polarizing plate 115 ......... Backlight unit 117 ......... Liquid crystal molecules

Claims (4)

A light transmissive substrate;
A multi-gap layer having a reverse trapezoidal cross section formed on the substrate;
A colored layer formed on the substrate and the multi-gap layer;
The protective layer is formed along the colored layer, and in the vicinity of the multi-gap layer, the protective layer has a substantially U-shaped cross-section with the opening facing downward,
A color filter comprising: Forming a multi-gap layer having an inverted trapezoidal cross section on a light-transmitting substrate;
Forming a colored layer on the substrate and on the multi-gap layer; and
Forming a protective layer along the colored layer (c);
With
In the vicinity of the multi-gap layer, the cross section of the protective layer has a substantially U-shaped cross section with the opening facing downward .   3. The method for producing a color filter according to claim 2, wherein the multi-gap layer is formed by excessive development in the step (a). 3. The method of manufacturing a color filter according to claim 2, wherein the multi-gap layer is formed by overexposure in the step (a).

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