Radiation imagery chemistry: process – composition – or product th – Radiation modifying product or process of making – Screen other than for cathode-ray tube
Reexamination Certificate
2002-09-19
2004-11-30
McPherson, John A. (Department: 1756)
Radiation imagery chemistry: process, composition, or product th
Radiation modifying product or process of making
Screen other than for cathode-ray tube
C349S106000, C349S113000
Reexamination Certificate
active
06824935
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a substrate having colored layers of different colors formed thereon, including colorless regions that are substantially colorless, and a method for producing the same. The substrate having colored layers of the present invention may be used in a reflective color liquid crystal display device that operates in a reflection display mode by reflecting incident light from the environment (hereinafter referred to also as “ambient light”), or in a transflective (hereinafter referred to also as “semi-transmissive”) color liquid crystal display device that operates in a reflection display mode under bright environments while operating in a transmission display mode by transmitting light from the backlight under dark environments.
2. Description of the Background Art
A semi-transmissive color liquid crystal display device is widely used as a display of a portable device, etc., as it is capable of operating in a reflection display mode using ambient light under bright environments, thereby reducing the power consumption, while operating in a transmission display mode using the backlight under dark environments, thereby making it possible to use the device under any environment.
A conventional semi-transmissive color liquid crystal display device is a two-way display type liquid crystal display device as disclosed in Japanese Laid-Open Patent Publication No. 11-183892. The publication discloses a liquid crystal display device in which openings are provided in red, green and blue color filters (hereinafter referred to also as “CFs”) provided on the inner surface of a front-side substrate so that each opening partially corresponds to a pixel region, with a reflection film being provided on the inner surface of a back-side substrate so as to correspond to the opening. When the liquid crystal display device operates in a reflection display mode, colored light, which has been transmitted through a portion of a CF other than the opening and reflected by a semi-transmissive reflector, and non-colored light of a high brightness, which has been transmitted through the opening of the CF and reflected by the reflection film, can be output in front of the device, thereby displaying a color image with a high brightness. When the liquid crystal display device operates in a transmission display mode, only colored light, which has been transmitted through the portion of the CF other than the opening, can be output in front of the device, thereby displaying a color image with a high contrast. Note that the publication discloses a pigment dispersion method as a CF formation method (see Paragraph [0040] of the publication).
Japanese Laid-Open Patent Publication No. 8-286178 discloses a reflective or transmissive liquid crystal display device in which a CF including a light-transmitting opening therein is provided for each pixel, and states that it is possible to realize a bright display with the device. The publication also describes the provision of a highly-transmissive CF in a region corresponding to the opening in the CF, and describes methods for forming the highly-transmissive CF, such as a photobleaching reaction of an organic pigment and a partial dying method (see Paragraphs [0103] to [0107] and
FIG. 8
of the publication).
Beside the pigment dispersion method, etc., described in the publications above, another CF formation method is a resist direct electrodeposition method as disclosed in, for example, Japanese Laid-Open Patent Publication No. 63-210901. A resist direct electrodeposition method, with which the process can be simplified and which is low in cost, is advantageous over other methods. A process of forming a CF by using a resist direct electrodeposition method will be described with reference to
FIG. 24A
to FIG.
24
J. First, a transparent conductive layer
82
and a positive-type photosensitive resin composition layer
83
are formed in this order on a substrate
81
(FIG.
24
A). After a positive-type mask
84
having a predetermined pattern is placed on the photosensitive resin composition layer
83
, the structure is exposed, and a portion of the photosensitive resin composition layer
83
in the exposed region thereof is eluted by using an eluent (FIG.
24
B). An electric current is passed through the transparent conductive layer
82
in an electrodeposition bath containing an electrodepositing polymer and a dye so as to electrodeposite R (red), for example (FIG.
24
C). Other hues, i.e., G (green) and B (blue), are electrodeposited in a manner as that for R (red), thereby forming the photosensitive resin composition layer
83
including colored portions therein (
FIG. 24D
to FIG.
24
G). Then, the entire photosensitive resin composition layer
83
is exposed, and the remaining photosensitive resin composition is eluted in an eluent, thereby leaving the R (red), G (green) and B (blue) color filters on the transparent conductive layer
82
. In a case where a CF with no opening (colorless region), as described in Japanese Laid-Open Patent Publication No. 63-210901, is formed, a high patterning precision is not required because it is only necessary to form a CF in each pixel. Note that in an opening in a CF, reflected light is not colored and is substantially colorless. The opening portion of the CF will be referred to also as “colorless region”.
However, in a case where a CF with an opening therein is formed, a poor patterning precision may result in variations in the area of the opening, leading to variations in the display chromaticity. Therefore, the formation of a CF having an opening therein is stringent as to the patterning precision, making the process control difficult.
With the resist direct electrodeposition method shown in Japanese Laid-Open Patent Publication No. 63-210901, the R, G and B CFs are successively formed by using the same photosensitive resin composition layer
83
. Therefore, the sensitivity of the photosensitive resin composition layer
83
gradually decreases, thereby decreasing the CF dimensional precision. Thus, in a case where an opening is formed in a CF by using the resist direct electrodeposition method, the precision in the position or area of the opening decreases along with the decrease in the CF dimensional precision.
In a case where the liquid crystal display device described in Japanese Laid-Open Patent Publication No. 11-183892 is formed by using the resist direct electrodeposition method, variations in the dimension of the CF cause variations in the area of the opening of the CF and, in turn, variations in the display chromaticity.
Japanese Laid-Open Patent Publication No. 8-286178 describes the provision of a highly-transmissive CF in a region corresponding to an opening by using a photobleaching reaction and a partial dying method. Also with these methods, it is necessary to perform a patterning process such as an exposure and development process, thereby causing variations in the area of the opening and, in turn, variations in the display chromaticity. Moreover, a method using the photobleaching reaction has a problem as to the reliability of the obtained CF, i.e., the CF is decolorized in a long-term use. With the partial dying method, a partial dying process needs to be performed for each color, thereby increasing the number of steps.
Moreover, in a case where a CF is formed on a synthetic resin substrate, such a substrate is subject to thermal expansion, which not only changes the dimension but also makes alignment difficult, thereby causing more serious variations in the chromaticity.
An object of the present invention is to provide a reflective or semi-transmissive color liquid crystal display device with a good visibility in which variations in the display chromaticity are reduced. Another object of the present invention is to provide a substrate having colored layers for use in such a liquid crystal display device, and a method for producing the same.
SUMMARY OF THE INVENTION
A substrate having colored layers of
Koyama Yoshihide
Tanaka Mitsuhiro
Yoshimura Kazuya
McPherson John A.
Nixon & Vanderhye P.C.
Sharp Kabushiki Kaisha
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