DAP type liquid crystal device with cholesteric liquid crystal birefringent layer

Claim 2

A DAP type-ECB system liquid crystal display device comprising: (1) a liquid crystal cell in which a liquid crystal layer is sandwiched between a pair of substrates each of which has at least one electrode; (2) a birefringent layer sandwiched between the liquid crystal cell and a substrate which does not have an electrode; and (3) a pair of polarizers sandwiching therebetween the liquid crystal cell, the birefringent layer and said substrate which does not have an electrode; wherein (i) light modulation of the liquid crystal display device is conducted by inputting an electric signal to the electrodes; (ii) the birefringent layer comprises a liquid crystal compound showing a cholesteric phase, or a polymer film obtained by quenching a polymer showing a cholesteric phase to fix the aligned direction of the polymer molecules, (iii) an axis of the helical structure of molecules of the compound or the film is substantially perpendicular to a plane of the birefringent layer; and (iv) a product of a pitch of the helical structure of the cholesteric liquid crystal phase or the polymer film and a refractive index in the maximum refractive index direction of the birefringent layer is smaller than 400 nm.

Claim 3

A DAP type-ECB system liquid crystal display device, comprising: (1) a liquid crystal cell in which a liquid crystal layer is sandwiched between a pair of substrates each of which has at least one electrode; (2) a birefringent layer sandwiched between the liquid crystal cell and a substrate which does not have an electrode; and (3) a pair of polarizers sandwiching therebetween the liquid crystal cell, the birefringent layer and said substrate which does not have an electrode; wherein (i) light modulation of the liquid crystal display device is conducted by inputting an electric signal to the electrodes; (ii) the birefringent layer comprises a liquid crystal compound showing a cholesteric phase, or a polymer film obtained by quenching a polymer showing a cholesteric phase to fix the aligned direction of the polymer molecules, and molecules of the liquid crystal or the polymer in the birefringent layer are substantially isotropic to visible rays within the plane of the birefringent layer, and the refractive index in a direction perpendicular to the plane is smaller than the average refractive index within this plane; (iii) an axis of the helical structure of molecules of the compound or the film is substantially perpendicular to a plane of the birefringent layer; and (iv) a product of a pitch of the helical structure of the cholesteric liquid crystal phase or a polymer film, and a refractive index in the maximum refractive index direction of the birefringent layer, is smaller than 400 nm.

Claim 4

A DAP type-ECB system liquid crystal display device, comprising: (1) a liquid crystal cell in which a liquid crystal layer is sandwiched between a pair of substrates each of which has at least one electrode; (2) a birefringent layer sandwiched between the liquid crystal cell and a substrate which does not have an electrode; and (3) a pair of polarizers sandwiching therebetween the liquid crystal cell, the birefringent layer and said substrate which does not have an electrode; wherein (i) light modulation of the liquid crystal display device is conducted by inputting an electric signal to the electrodes; (ii) the birefringent layer comprises a liquid crystal compound showing a cholesteric phase, or a polymer film obtained by quenching a polymer showing a cholesteric phase to fix the aligned direction of the polymer molecules, and molecules of the liquid crystal or the polymer in the birefringent layer are substantially isotropic to visible rays within the plane of the birefringent layer, and the refractive index in a direction perpendicular to the plane is smaller than the average refractive index within this plane; (iii) an axis of the helical structure of molecules of the compound or the film is substantially perpendicular to a plane of the birefringent layer; and (iv) a product of a pitch of the helical structure of the cholesteric liquid crystal phase or a polymer film, and a refractive index in the maximum refractive index direction of the birefringent layer, is smaller than 400 nm.

Claim 5

A DAP type-ECB system liquid crystal display device, comprising: (1) a liquid crystal cell in which a liquid crystal layer is sandwiched between a pair of substrates each of which has at least one electrode; (2) a birefringent layer sandwiched between the liquid crystal cell and one of a pair of polarizers; and (3) a pair of polarizers sandwiching therebetween the liquid crystal cell the birefringent layer; wherein (i) light modulation of the liquid crystal display device is conducted by inputting an electric signal to the electrodes; (ii) the birefringent layer comprises a polymer film obtained by quenching a polymer showing a cholesteric phase to fix the aligned direction of the polymer molecules, and molecules of the polymer in the birefringent layer are substantially isotropic to visible rays within the plane of the birefringent layer, and the refractive index in a direction perpendicular to the plane is smaller than the average refractive index within the plane; (iii) an axis of the helical structure of molecules of the compound or the film is substantially perpendicular to a plane of the birefringent layer; and (iv) a product of a pitch of the helical structure of the cholesteric liquid crystal phase or the polymer film, and a refractive index in the maximum refractive index direction of the birefringent layer is smaller than 400 nm.

Claim 6

A DAP type-ECB system liquid crystal display device, comprising: (1) a liquid crystal cell in which a liquid crystal layer is sandwiched between a pair of substrates each of which has at least one electrode; (2) a birefringent layer sandwiched between the liquid crystal cell and one of a pair of polarizers; and (3) a pair of polarizers sandwiching therebetween the liquid crystal cell the birefringent layer; wherein (i) light modulation of the liquid crystal display device is conducted by inputting an electric signal to the electrodes; (ii) the birefringent layer comprises a polymer film obtained by quenching a polymer showing a cholesteric phase to fix the aligned direction of the polymer molecules, and molecules of the polymer in the birefringent layer are substantially isotropic to visible rays within the plane of the birefringent layer, and the refractive index in a direction perpendicular to the plane is smaller than the average refractive index within the plane; (iii) an axis of the helical structure of molecules of the compound or the film is substantially perpendicular to a plane of the birefringent layer; and (iv) a product of a pitch of the helical structure of the cholesteric liquid crystal phase or the polymer film, and a refractive index in the maximum refractive index direction of the birefringent layer is smaller than 400 nm.

Claim 7

A device as defined in claim 2 or 3, wherein said polymer comprises a copolymer of benzyl-L-glutamate and dodecyl-L-glutamate.

Claim 8

The device according to claim 2 or 3, wherein the polymer comprises a copolymer obtained by a reaction of 4,4'-dihydroxybiphenyl, (+)-3-methyladipic acid and an aliphatic dicarboxylic acid.

Claim 9

The device according to claim 2 or 3, wherein said liquid crystal compound is selected from azomethine compounds represented by the formula: ##STR6##

Claim 10

The device according to claim 2 or 3, wherein said liquid crystal compound is selected from azoxy compounds represents by the formula: ##STR7##

Claim 11

The device according to claim 2 or 3, wherein said liquid crystal compound is selected from ester compounds represented by the formula: ##STR8##