JP3613807B2 - Color polarizing filter and liquid crystal display device using the same - Google Patents

Description

[0001]
[Industrial application fields]
The present invention relates to a liquid crystal display device used for a computer terminal, a television, an in-vehicle navigation system, and the like, and a color polarizing filter used therefor.
[0002]
[Prior art]
In recent years, display devices are required to save space and portability as display devices for personal computers, portable information terminals, and portable televisions. In order to satisfy this requirement, liquid crystal display devices are rapidly spreading as flat display devices instead of conventional CRTs.
[0003]
Since the liquid crystal display device is originally a non-light-emitting device, an external light source such as a backlight is required. In order to perform color display, (1) the color filter system is used, and (2) the three primary color polarizing filters described in Trikes WS51p86 to p87 are known.
[0004]
FIG. 3 schematically shows a cross-sectional structure of a liquid crystal display device incorporating (1). A pixel electrode 8 and an alignment film 3 are formed on the glass substrate 1, and the alignment film 3 is subjected to an alignment process such as rubbing in order to align liquid crystal. On the other hand, color filters 9R, 9G, and 9B composed of red, green, and blue color patterns are installed on the opposite glass substrate 2, and a black matrix 11 is provided between the color patterns to increase the sharpness of the image. Arranged as needed. Furthermore, the counter electrode 5 and the alignment film 4 are provided thereon, and the alignment treatment is similarly performed.
[0005]
In order to configure as a liquid crystal display device, the glass substrates 1 and 2 are opposed to each other so that the electrode sides face each other, and a liquid crystal is sealed therebetween. The liquid crystal used at this time is usually TN (Twisted Nematic) liquid crystal or STN (Super Twisted Nematic) liquid crystal, and is set so that the liquid crystal molecules are twisted and aligned in the range of 90 ° to 270 ° according to each mode. The orientation is controlled.
[0006]
In order to display on such a liquid crystal panel, an optical shutter effect due to the electro-optical characteristics of the liquid crystal is used. That is, generally, the polarizing plates 7 and 11 are installed on both outer sides of the liquid crystal panel, and the shutter effect is exhibited by the change in the optical rotation of the liquid crystal due to the electric field. At this time, one polarizing plate is provided for the normally white mode.
[0007]
In recent years, with dramatic improvements in the performance of liquid crystal display devices and the expansion of application fields, high-quality display performance typified by full-color display such as TV image display has been demanded, and demand for larger liquid crystal display devices is also required. Is growing.
[0008]
In a conventional liquid crystal display device, the color filter 9 and the polarizing plate 10 are installed with a glass substrate interposed therebetween. On the other hand, the thickness of the glass substrate is usually 1.1 mm, and even if it is made thinner, it is said that 0.7 mm is the limit because it is restricted in terms of manufacturing equipment and handling. Accordingly, since it is impossible to make the distance between the color filter 9 and the polarizing plate 10 short, a clear display can be obtained when viewed from the front, but the viewing angle dependency is lost when viewing from an oblique direction. Inevitably, this is a major problem in improving the display image quality of liquid crystal display devices and increasing the screen size.
[0009]
In addition, the three primary color polarizing filter of the method (2) has three colors of red, green and blue, and there is a problem that black and white display cannot be performed with this combination.
[0010]
[Problems to be solved by the invention]
The present invention was created as a result of intensive studies to solve the problems of such liquid crystal display devices, and the problem is that the viewing angle dependency is small and high-quality display is possible. An object of the present invention is to provide a liquid crystal display device suitable for screen display.
[0011]
In order to solve this problem, the present invention applies a transparent resin on a transparent substrate, and paints a pigment composed of dichroic dyes of four colors , red, green, blue and black, on the surface subjected to rubbing treatment. Provided is a color polarizing filter for a liquid crystal display device comprising a color filter layer having a polarizing function, and a dichroic surface on a surface subjected to rubbing treatment by applying a transparent resin on a transparent substrate. A liquid crystal in which liquid crystal is sealed in a liquid crystal cell composed of a color polarizing filter having a color filter layer having a polarizing function formed by separately coating dyes composed of a dye and a polarizing plate. A display device is provided.
[0012]
The present invention will be described below with reference to the drawings. FIG. 1 shows an example of a cross-sectional configuration of a liquid crystal display device according to the present invention. A polymer film such as polyvinyl alcohol, polyimide, polyetherimide, polyamideimide, polyvinyl chloride, or the like is applied on the glass substrate 2 and rubbed.
[0013]
Here, the rubbing treatment is a treatment method in which a polymer film is rubbed in one direction with a rubbing cloth by a known means such as a rubbing apparatus to form fine grooves on the polymer surface. At this time, the rubbing direction is performed so as to have a predetermined angle with the alignment direction of the liquid crystal to be sealed thereafter in order to define the direction of the deflection axis.
[0014]
Next, a positive photosensitive resin is coated thereon, and an arbitrary pattern is exposed by exposure and development through a photomask. Next , a color polarizing filter 7 having a color filter layer and a black matrix is formed by repeating red, green, blue, and black in order by applying or dipping an aqueous solution in which a suitable dichroic dye such as disazo, trisazo, and dianisidine is dispersed. Is made. The arrangement of the four colors at this time can be appropriately performed in a mosaic shape, a stripe shape, or the like. Further, a protective film made of an inorganic material made of an organic polymer such as an acrylic resin, a urethane resin, or an epoxy resin, silicon dioxide, alumina, silicon nitride, or the like is appropriately formed on the color polarizing filter 7 as necessary.
[0015]
Next, a transparent conductive thin film such as ITO (Indium-Tin-Oxide), tin oxide or the like is formed using a known means such as a sputtering method and, if necessary, a means such as photo-etching or lift-off method, and the pixel electrode 5 Form.
[0016]
Further, an alignment film 4 made of polyimide for aligning liquid crystal is applied on the substrate, and alignment treatment is performed by the rubbing method described above. This alignment direction is determined in consideration of the display mode of the liquid crystal to be used and the polarization direction of the color polarizing filter 7 formed below.
[0017]
On the other hand, the transparent conductive thin film described above is patterned on the transparent substrate 1 made of glass, plastic film or the like as the counter substrate to form the pixel electrode 8, and the alignment film 3 made of polyimide is applied on the pixel electrode 8, and similarly rubbed. Alignment treatment is performed by such means.
[0018]
Next, the transparent substrates 1 and 2 are combined so that the pixel electrodes 8 and 5 face each other at a predetermined interval (generally 2 to 15 μm), and a liquid crystal is sealed therebetween. As the liquid crystal to be sealed at this time, nematic liquid crystal is generally used, but not limited thereto.
[0019]
Finally, in this liquid crystal panel, a polarizing plate 6 for normally white mode is combined on the outside of the transparent substrate 1 to complete a liquid crystal display device.
[0020]
[Action]
According to the liquid crystal display device using the color polarizing filter according to the present invention, at least one substrate is a transparent glass substrate, and the color polarizing layer and the color filter are integrated into the color filter layer and the polarization. Since there is no gap between layers, a liquid crystal display device that has less viewing angle dependency, high image quality, and capable of displaying a large screen can be provided.
[0021]
【Example】
FIG. 2 shows an outline of the manufacturing process of the color polarizing filter of the present invention, and the present invention will be described in detail based on the examples.
[0022]
<Example 1>
A polyvinyl alcohol resin (manufactured by Fuji Chemical Co., Ltd.) was applied to the glass substrate 2 of FIG. 2 made of silica-coated alkali glass with a spin coater and dried. At this time, the film thickness of the polyvinyl alcohol resin was about 1 μm. Next, this surface was rubbed with a commercially available rubbing apparatus. The rubbing cloth used at this time was made of nylon and had a hair tip length of 1 mm.
[0023]
Next, a positive photosensitive resin (trade name AZ-1350, manufactured by Hoechst Co., Ltd.) is uniformly applied to the substrate that has been subjected to the rubbing treatment. Next, the portion to be colored is exposed and developed through a photomask to expose the polyvinyl film. It was immersed in a 0.2 wt% dye aqueous solution in which a highly dichroic pigment “CIDirectRed81” was dissolved to dye the red of the dichroic dye to impart polarization. Next, the portion to be colored was exposed and developed through a photomask in the same manner as red, and the exposed polyvinyl film surface was immersed in a 0.4 wt% dye aqueous solution in which “CIDirectGreen63” was dissolved to stain green and impart polarizing properties. A blue pattern was created using “CIDirectBlue202” as well as red and green. Finally, a black pattern was prepared using 70%, 10%, and 20% of “Blue202”, “Green63” and “Red81”, and the remaining positive photosensitive resin was peeled off. A color polarizing filter having red, green, blue and black color filter layers (9R, 9G, 9B) and a black matrix 11 was completed.
[0024]
<Example 2>
On the color polarizing filter of Example 1, an ITO film is formed as a transparent electrode using a sputtering apparatus. At this time, an arbitrary pattern was formed from the ITO film to form a pixel electrode. The ITO film thickness at this time was 100 nm, and the sheet resistance value of this film was about 30Ω / □. Further, a polyimide film (trade name LQT-120, manufactured by Nippon Synthetic Rubber Co., Ltd.) is applied as an alignment material on this substrate to a film thickness of about 90 nm, and then subjected to alignment treatment by rubbing using a rubbing apparatus. A film is formed. At this time, the alignment treatment direction was set in a direction parallel to the polarization axis of the polarizing layer.
[0025]
As the counter substrate, an active matrix element substrate including a TFT using amorphous Si as a semiconductor and a pixel electrode 9 connected thereto was manufactured on a transparent substrate formed of a low alkali glass substrate by a semiconductor process. The number of pixels at this time was 300 × 240 pixels, and the display area was about 6 cm diagonal.
[0026]
Further, polyimide is applied to the substrate as an alignment material, and a rubbing process is performed to form an alignment film. The materials used at this time are the same as those described above. Further, the rubbing direction at this time was performed so as to be at an angle of 90 ° with the alignment direction of the color filter side substrate.
[0027]
Next, spacers are spread over these substrates at regular intervals, and the periphery is bonded using an epoxy resin-based sealing material (trade name: Struct Bond, manufactured by Mitsui Toatsu Chemical Co., Ltd.). A cell was produced. At this time, the distance between the substrates was set to about 5 μm.
[0028]
And after encapsulating nematic liquid crystal (trade name ZLI-4792, manufactured by Merck Japan Co., Ltd.) in this liquid crystal cell, the enclosing port was sealed with a sealing material. Finally, a polarizing plate is attached to the outer counter substrate side of the liquid crystal panel so that the polarization axis forms an angle of 90 ° with respect to the alignment axis of the polarizing layer inside the liquid crystal panel, so that the liquid crystal is set to a normally white mode. A display device was completed.
[0029]
【The invention's effect】
According to the liquid crystal display device using the color polarizing filter composed of four colors of red, green, blue, and black according to the present invention, at least one substrate is a transparent glass substrate, and the polarizing layer and the color filter include Since the distance between the color filter layer and the polarizing layer is negligible, the viewing angle dependency is small and high-quality display is possible.
[0030]
Therefore, a multi-color large-screen liquid crystal display device capable of high-quality display can be easily provided.
[0031]
[Brief description of the drawings]
FIG. 1 is an explanatory diagram showing a cross-sectional structure of an example of a liquid crystal display device of the present invention.
FIG. 2 is an explanatory diagram showing an example of a manufacturing process of a color polarizing filter of the present invention.
FIG. 3 is an explanatory diagram showing a cross-sectional structure of an example of a conventional liquid crystal display device.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... Glass substrate 2 ... Glass substrate 3 ... Orientation film 4 ... Orientation film 5 ... Pixel electrode 6 ... Polarizing plate 7 ... Color polarizing filter 8 ... Pixel electrode 9R ... Red color filter layer 9G ... Green color filter layer 9B ... Blue color filter Layer 10 ... Polarizing plate 11 ... Black matrix

Claims (2)

A color filter having a polarization function, which is formed by coating a transparent resin on a transparent substrate and coating the surface which has been subjected to rubbing treatment with pigments composed of dichroic dyes of four colors of red, green, blue and black. A color polarizing filter for a liquid crystal display device comprising a layer. A color filter having a polarization function, which is formed by coating a transparent resin on a transparent substrate and coating the surface on which the rubbing treatment has been performed with different colors of red, green, blue and black dichroic dyes. A liquid crystal display device, wherein a liquid crystal is sealed in a liquid crystal cell composed of a color polarizing filter having a layer and a counter substrate having a polarizing plate.

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