Liquid crystal display device and projection display apparatus

Abstract

A liquid crystal display device capable of obtaining a high contrast ratio within a range of entry angles of source light to an optical modulation device of a projection display apparatus has a liquid crystal panel operating in a twisted nematic mode, a first optical compensating plate disposed at the light-entry side of the liquid crystal panel, and a second optical compensating plate disposed at the light-exit side thereof. The respective optical compensating plates hybrid-aligns liquid crystal molecules having a negative birefringence, a phase retardation in the normal direction thereof of 10 nm or more and 30 nm or less, and fast axis directions, as seen in the respective normal directions, intersect each other at an angle other than a right angle.

1 . A liquid crystal display device, comprising:
 a liquid crystal panel having a pair of substrates and a twisted nematic liquid crystal layer interposed between the pair of substrates;   a light source that illuminates the liquid crystal panel;   a first optical compensating plate disposed at a side of the liquid crystal panel on which light from the light source falls incident, the first optical compensating plate including hybrid-aligned liquid crystal molecules that have a negative birefringence property, the first optical compensating plate having a phase retardation property with respect to a viewing direction that is normal to the first optical compensating plate, the phase retardation property being within a range of 10 nm to 30 nm, the first optical compensating plate having a fast axis in a first direction; and   a second optical compensating plate disposed at an opposite side of the liquid crystal panel than the first optical compensating plate, the second optical compensating plate including hybrid-aligned liquid crystal molecules that have a negative birefringence property, the second optical compensating plate having a phase retardation property with respect to a viewing direction that is normal to the second optical compensating plate, the phase retardation property being within a range of 10 nm to 30 nm, the second optical compensating plate having a fast axis in a second direction that intersects the first direction at an angle other than a right angle;   wherein the first and second optical compensating plate each have a first surface and a second surface opposite from each other, liquid crystal molecules adjacent to the first surface being aligned so that their optical axis direction forms an angle with a direction normal to the optical compensating plate that is larger than an angle between an optical axis direction of liquid crystal molecules adjacent to the second surface and the direction normal to the optical compensating plate, the first optical compensating plate being arranged so that light from the light source falls incident on the second surface, and the second optical compensating plate being arranged so that light from the light source falls incident on the first surface.   
   
   
       2 . A liquid crystal display device, comprising:
 a liquid crystal panel having a pair of substrates and a twisted nematic liquid crystal layer interposed between the pair of substrates;   a light source that illuminates the liquid crystal panel;   a first optical compensating plate disposed at a side of the liquid crystal panel on which light from the light source falls incident, the first optical compensating plate including hybrid-aligned liquid crystal molecules that have a negative birefringence property, the first optical compensating plate having a phase retardation property with respect to a viewing direction that is normal to the first optical compensating plate, the phase retardation property being within a range of 10 nm to 30 nm, the first optical compensating plate having a fast axis in a first direction; and   a second optical compensating plate disposed at the side of the first optical compensating plate on which light from the light source falls incident, the second optical compensating plate including hybrid-aligned liquid crystal molecules that have a negative birefringence property, the second optical compensating plate having a phase retardation property with respect to a viewing direction that is normal to the second optical compensating plate, the phase retardation property being within a range of 10 nm to 30 nm, the second optical compensating plate having a fast axis in a second direction that intersects the first direction at an angle other than a right angle;   wherein the first and second optical compensating plate each have a first surface and a second surface opposite from each other, the liquid crystal molecules adjacent to the first surface being aligned so that their optical axis direction forms an angle with a direction normal to the optical compensating plate that is larger than an angle between an optical axis direction of the liquid crystal molecules adjacent to the second surface and the direction normal to the optical compensating plate, the first optical compensating plate being arranged so that light from the light source falls incident on the second surface, and the second optical compensating plate being arranged so that light from the light source falls incident on the first surface.   
   
   
       3 . A liquid crystal display device, comprising:
 a liquid crystal panel having a pair of substrates and a twisted nematic liquid crystal layer interposed between the pair of substrates;   a light source that illuminates the liquid crystal panel;   a first optical compensating plate disposed at a side of the liquid crystal panel that is opposite to a side on which light from the light source falls incident, the first optical compensating plate including hybrid-aligned liquid crystal molecules that have a negative birefringence property, the first optical compensating plate having a phase retardation property with respect to a viewing direction that is normal to the first optical compensating plate, the phase retardation property being within a range of 10 nm to 30 nm, the first optical compensating plate having a fast axis in a first direction; and   a second optical compensating plate disposed between the liquid crystal panel and the first optical compensating plate, the second optical compensating plate including hybrid-aligned liquid crystal molecules that have a negative birefringence property, the second optical compensating plate having a phase retardation property with respect to a viewing direction that is normal to the second optical compensating plate, the phase retardation property being within a range of 10 nm to 30 nm, the second optical compensating plate having a fast axis in a second direction that intersects the first direction at an angle other than a right angle;   wherein the first and second optical compensating plates each have a first surface and a second surface opposite from each other, the liquid crystal molecules adjacent to the first surface being aligned so that their optical axis direction forms an angle with a direction normal to the respective optical compensating plate that is larger than an angle between an optical axis direction of the liquid crystal molecule adjacent to the second surface and the direction normal to the respective optical compensating plate, the first optical compensating plate being arranged so that light from the light source falls incident on the second surface, and the second optical compensating plate being arranged so that light from the light source falls incident on the first surface.   
   
   
       4 . The liquid crystal display device according to  claim 1 , wherein
 at least, the first optical compensating plate being disposed such that the fast axis thereof is parallel to an alignment control direction of one substrate of the pair of substrates on the side where the light source be arranged, or the second optical compensating plate being disposed such that the fast axis thereof is parallel to an alignment control direction of the other substrate of the pair of substrates on the side opposite to the light source.   
   
   
       5 . The liquid crystal display device according to  claim 2 , wherein
 at least, the first optical compensating plate being disposed such that the fast axis thereof is parallel to an alignment control direction of one substrate of the pair of substrates on the side where the light source be arranged, or the second optical compensating plate being disposed such that the fast axis thereof is parallel to an alignment control direction of the other substrate of the pair of substrates on the side opposite to the light source.   
   
   
       6 . The liquid crystal display device according to  claim 3 , wherein
 at least, the first optical compensating plate being disposed such that the fast axis thereof is parallel to an alignment control direction of one substrate of the pair of substrates on the side where the light source be arranged, or the second optical compensating plate being disposed such that the fast axis thereof is parallel to an alignment control direction of the other substrate of the pair of substrates on the side opposite to the light source.   
   
   
       7 . The liquid crystal display device according to  claim 1 , wherein
 an intersection angle at which the first direction and the second direction intersect each other being an angle at which a contrast ratio of the liquid crystal display device is at a maximum within a range of 91° to 110°.   
   
   
       8 . The liquid crystal display device according to  claim 2 , wherein
 an intersection angle at which the first direction and the second direction intersect each other being an angle at which a contrast ratio of the liquid crystal display device is at a maximum within a range of 91° to 110°.   
   
   
       9 . The liquid crystal display device according to  claim 3 , wherein
 an intersection angle at which the first direction and the second direction intersect each other being an angle at which a contrast ratio of the liquid crystal display device is at a maximum within a range of 91° to 110°.   
   
   
       10 . A projection display apparatus, comprising:
 the liquid crystal display device according to  claim 1  usable as an optical modulation device.   
   
   
       11 . A projection display apparatus, comprising:
 the liquid crystal display device according to  claim 2  usable as an optical modulation device.   
   
   
       12 . A projection display apparatus, comprising:
 the liquid crystal display device according to  claim 3  usable as an optical modulation device.