Liquid crystal display device comprising improved viewing angle characteristics

Claim 2

A liquid crystal display device comprising: a display cell layer for displaying an image thereon, said display cell layer containing a liquid crystal layer arranged between a pair of optically transparent substrates; a pair of polarizers arranged on the sides of respective outer surfaces of said display cell layer; said liquid crystal display device being characterized in that, said liquid crystal display device further comprises: retardation compensation layer having an optical birefringence for compensating a change in the retardation caused when light passes through said display cell layer so as to improve viewing angle characteristics, said retardation compensation layer being arranged on at least one side in a direction of the thickness of said display cell layer and between said polarizers; and a direction of a maximum one of principal refractive indices of said retardation compensation layer is oriented in a direction substantially parallel to a direction of the normal perpendicular to the surfaces of the transparent substrates of said display cell layer.

Claim 3

The liquid crystal display device as claimed in claim 1, wherein said retardation compensation layer contains a liquid crystal layer arranged between another pair of optically transparent substrates, and liquid crystal molecules are arranged in said liquid crystal layer of said retardation compensation layer so that the principal axes thereof are substantially perpendicular to respective surfaces of said optically transparent substrates.

Claim 4

The liquid crystal display device as claimed in claim 2, wherein the retardation Δn1·d1 which is the product of the birefringence Δn1 and the thickness d1 of the liquid crystal layer of said display cell layer and the retardation Δn2·d2 which is the product of the birefringence Δn2 and the thickness d2 of the liquid crystal layer of said retardation compensation layer are set so as to fall within the following ranges: 0.3 µms < Δn1 ·d1 < 0.6 µms, and 0.05 µms < Δn2 ·d2 < 0.3 µms.

Claim 5

The liquid crystal display device as claimed in claim 1, wherein said retardation compensation layer is made by shaping a polymeric liquid crystal material comprising liquid crystal molecules having principal axes parallel in a predetermined direction into a film configuration, and said retardation compensation layer is arranged so that the principal axes of the liquid crystal molecules of said polymer liquid crystal material are substantially perpendicular to respective surfaces of said optically transparent substrates.

Claim 6

The liquid crystal display device as claimed in claim 1, wherein liquid crystal of the liquid crystal layer of said display cell layer are twisted at right angle, and the polarization axes of said polarizers cross each other at right angle.

Claim 7

The liquid crystal display device as claimed in claim 1, wherein said display cell layer is constituted by a twisted nematic type liquid crystal device.

Claim 8

The liquid crystal display device as claimed in claim 1, wherein said display cell layer is constituted by a super twisted nematic type liquid crystal device.

Claim 9

A liquid crystal display device comprising: a display cell layer for displaying an image thereon, said display cell layer containing a liquid crystal layer arranged between a pair of first and second optically transparent substrates; a pair of polarizers arranged on the sides of respective outer surfaces of said display cell layer; a pair of first and second phase difference cancellation films for canceling a phase difference between ordinary light and extraordinary light generated by an optical birefringence of said display cell layer, said first phase difference cancellation film being arranged between said first optically transparent substrate and said first polarizer, said second phase difference cancellation film being arranged between said second optically transparent substrate and said second polarizer; said liquid crystal display device being characterized in that, said liquid crystal display device further comprises: retardation compensation layer having an optical birefringence for compensating a change in the retardation caused when light passes through said display cell layer so as to improve viewing angle characteristics, said retardation compensation layer being arranged on at least one side in a direction of the thickness of said display cell layer and between said polarizers; and a direction of a maximum one of principal refractive indices of said retardation compensation layer is oriented in a direction substantially parallel to a direction of the normal perpendicular to the surfaces of the transparent substrates of said display cell layer.

Claim 10

A liquid crystal display device comprising: a display cell layer for displaying an image thereon, said display cell layer containing a liquid crystal layer arranged between a pair of first and second optically transparent substrates; a pair of polarizers arranged on the sides of respective outer surfaces of said display cell layer; a pair of first and second phase difference cancellation films for canceling a phase difference between ordinary light and extraordinary light generated by an optical birefringence of said display cell layer, said first phase difference cancellation film being arranged between said first optically transparent substrate and said first polarizer, said second phase difference cancellation film being arranged between said second optically transparent substrate and said second polarizer; said liquid crystal display device being characterized in that, said liquid crystal display device further comprises: retardation compensation layer having an optical birefringence for compensating a change in the retardation caused when light passes through said display cell layer so as to improve viewing angle characteristics, said retardation compensation layer being arranged on at least one side in a direction of the thickness of said display cell layer and between said polarizers; and a direction of a maximum one of principal refractive indices of said retardation compensation layer is oriented in a direction substantially parallel to a direction of the normal perpendicular to the surfaces of the transparent substrates of said display cell layer.

Claim 11

The liquid crystal display device as claimed in claim 8, wherein said retardation compensation layer is arranged between said second phase difference cancellation film and said second polarizer.

Claim 12

The liquid crystal display device as claimed in claim 8, wherein said display cell layer is constituted by a twisted nematic type liquid crystal device.

Claim 13

The liquid crystal display device as claimed in claim 8, wherein said display cell layer is constituted by a super twisted nematic type liquid crystal device.

Claim 14

The liquid crystal display device as claimed in claim 11, wherein the liquid crystal of said liquid crystal layer is twisted at an angle of 240° between a pair of first and second optically transparent substrates.

Claim 15

The liquid crystal display device as claimed in claim 8, wherein at least one of said first and second phase difference cancellation films is composed of laminated plural phase difference cancellation films.

Claim 16

A liquid crystal display device comprising a first liquid crystal cell with means for altering the optical characteristics of a liquid crystal layer thereof in accordance with an image to be displayed, and a second liquid crystal cell superposed on the first and having a liquid crystal layer with an optical birefringence for compensating for change in the retardation caused when light passes through the first liquid crystal cell, the direction of the maximum principal refractive index of the liquid crystal layer of the second cell being substantially perpendicular to the plane of the liquid crystal layer of the first cell.

Claim 17

A liquid crystal display device comprising a first liquid crystal cell with means for altering the optical characteristics of a liquid crystal layer thereof in accordance with an image to be displayed, and a second liquid crystal cell superposed on the first and having a liquid crystal layer with an optical birefringence for compensating for change in the retardation caused when light passes through the first liquid crystal cell, the direction of the maximum principal refractive index of the liquid crystal layer of the second cell being substantially perpendicular to the plane of the liquid crystal layer of the first cell.