Optical: systems and elements – Polarization without modulation – With color filter
Reexamination Certificate
2001-08-06
2003-04-22
Robinson, Mark A. (Department: 2872)
Optical: systems and elements
Polarization without modulation
With color filter
C359S506000, C349S106000
Reexamination Certificate
active
06552849
ABSTRACT:
TECHNICAL FIELD
The present invention relates to a color polarizing plate with a support for a liquid crystal projector as well as to a liquid crystal projector. Particularly, the present invention relates to a color polarizing plate with a support suitable for a blue channel, which has both good brightness and polarizing efficiency as well as to a color liquid crystal projector using this color polarizing plate.
RELATING ART
In a color liquid crystal projection type display, namely, a color liquid crystal projector, polarizing plates are used in the liquid crystal image-forming section. Then, the reduction in brightness is inevitable because the light is sharply absorbed by the polarizing plates and because the image with an area as small as 1 inch to 6 inches is expanded to that having an area of about 10 inches to 100 and several tens inches. Therefore, the light source having high luminosity is used. On the other hand, there are tenacious demands for further improving the brightness of current projectors. As a consequence, it is reasonable that the light source to be used in such a projector becomes intensified more and more.
In the meantime, a neutral gray iodine-based polarizing plate having good polarizing efficiency was generally used as the polarizing plate in the liquid crystal image-forming section of the color liquid crystal projector. However, because the iodine-based polarizing plate uses iodine as the polarizer, there is the problem of insufficient light resistance, heat resistance and wet heat resistance. In order to solve this problem, a neutral gray polarizing plate using a dye-based dichroic dyestuff as the polarizer has come to be used. However, because the polarizing plate uses a combination of dyes of three primary colors, there is the problem that the transmittance of light of from 420 to 500 nm, so-called the blue channel, is low and the intensity of the light source must be more increased. In order to solve such a problem, three of color polarizing plates, i.e., red channel, green channel and blue channel, which correspond to three primary colors have come to be used.
However, among these three color polarizing plates, there is no color polarizing plate for blue channel (for blue light) which shows both good brightness and polarizing efficiency. The improvement of the color polarizing plate for blue channel has therefore been desired.
DISCLOSURE OF THE INVENTION
The inventors of the present invention have conducted various studies to solve the aforementioned problem and found that a color polarizing plate for blue channel (for blue light) which has both good brightness and polarizing efficiency can be obtained by combining a specific dichroic dyestuff. Accordingly, the present invention relates to:
(1) A color polarizing plate with a support for a liquid crystal projector comprising a polarizing plate containing a stilbene type water-soluble azo dye as a dichroic molecule and a support, wherein the polarizing plate has an average single transmittance of 39% or more and an average crossed transmittance of 0.4% or less at 420 to 500 nm and an average crossed transmittance of 60% or more at 650 to 780 nm.
(2) The color polarizing plate with a support for a liquid crystal projector according to (1), wherein the stilbene type water-soluble azo dye is a reaction product between 4,4′-dinitro-2,2′-stilbenedisulfonic acid and a monoazo compound having an aminophenylazobenzene structure.
(3) The color polarizing plate with a support for a liquid crystal projector according to (2), wherein the monoazo compound having an aminophenylazobenzene structure is a dye represented by the formula (1) as a free acid:
wherein R
1
and R
2
independently represent a hydrogen atom, an alkyl group or an alkoxy group, R
3
represents a sulfonic acid group or a carboxyl group and R
4
represents a hydrogen atom, a hydroxyl group or an alkoxy group.
(4) The color polarizing plate with a support for a liquid crystal projector according to any one of (1) to (3), the plate containing a J acid type water-soluble azo dye as the dichroic molecule.
(5) The color polarizing plate with a support for a liquid crystal projector according to (4), wherein the J acid type water-soluble azo dye is a water-soluble azo dye having a benzeneazobenzeneazo J acid structure.
(6) The color polarizing plate with a support for a liquid crystal projector according to (5), wherein the water-soluble azo dye having the benzeneazobenzeneazo J acid structure is a dye represented by the formula (2) as a free acid:
wherein R
5
represents a sulfonic acid group or a carboxyl group, R
6
represents a hydrogen atom, a hydroxyl group or an alkoxy group, R
7
and R
8
independently represent a hydrogen atom, a hydroxyl group, an alkyl group or an alkoxy group and R
9
represents an amino group, a substituted amino group or a substituted phenylazo group.
(7) The color polarizing plate with a support for a liquid crystal projector according to (6), wherein the substituted amino group of R
9
is a phenylamino group, a benzoylamino group or a p-aminobenzoylamino group and the substituted phenylazo group is a 4-hydroxyphenyl-1-azo group.
(8) The color polarizing plate with a support for a liquid crystal projector according to any one of (4) to (7), wherein the proportion of the J acid type water-soluble azo dye to be used is 80% by weight or less of the total amount of the dichroic molecule.
(9) The color polarizing plate with a support for a liquid crystal projector according to any one of (1) to (8), wherein the support is a glass molded or formed article.
(10) The color polarizing plate with a support for a liquid crystal projector according to (9), wherein the glass molded or formed article is a molded or formed article made of inorganic glass or organic glass.
(11) The color polarizing plate with a support for a liquid crystal projector according to (9) or (10), wherein the glass molded or formed article is a glass plate, a lens or a prism.
(12) The color polarizing plate with a support for a liquid crystal projector according to (9), wherein the glass molded or formed article is a liquid crystal cell.
(13) The color polarizing plate with a support for a liquid crystal projector according to any one of (1) to (12), wherein the plate is used for a blue channel.
(14) A color liquid crystal projector wherein the color polarizing plate with a support according to any one of (1) to (12) being arranged in a blue channel.
(15) A color liquid crystal projector wherein the color polarizing plate with a support according to any one of (1) to (11) being arranged on the incident side of a liquid crystal cell for blue channel so as not to be in contact with the liquid crystal cell.
(16) The color liquid crystal projector according to (15), wherein the polarizing plate surface of the color polarizing plate with a support on the incident side is arranged on the side of the liquid crystal cell.
(17) A color liquid crystal projector wherein the color polarizing plate with a support according to any one of (1) to (11) being arranged on the exit side of a liquid crystal cell for blue channel so as not to be in contact with the liquid crystal cell.
(18) A color liquid crystal projector wherein the color polarizing plates with a support according to (11) being arranged on each of the incident and exit sides of a liquid crystal cell for blue channel so as not to be in contact with the liquid crystal cell.
(19) A color liquid crystal projector wherein the color polarizing plate with a support according to (12) being arranged as a liquid crystal cell for blue channel such that the surface of the polarizing plate is made to be the exit side.
(20) The color liquid crystal projector according to (19), wherein the color polarizing plate with a support according to (11) is arranged on the incident side of a liquid crystal cell for blue channel so as not to be in contact with the liquid crystal cell.
(21) A color polarizing plate with a support for a liquid crystal projector comprising a polarizing plate containing a stilbene type w
Furuhashi Shigeki
Kawabe Kazuyuki
Matsuo Tadashi
Nields & Lemack
Nippon Kayaku Kabushiki Kaisha
Pritchett Joshua
Robinson Mark A.
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