PRODUCTION OF PHASE DIFFERENCE PLATE IMPROVED IN VISUAL FIELD ANGLE CHARACTERISTIC

摘要

PURPOSE:To obtain the phase difference plate which is free from coloration even when viewed from a plant direction and is improved in a visual field angle characteristic when this plate is used for a liquid crystal display plate. CONSTITUTION:A polycarbonate film (149 deg.C glass transition point) having 200mu thickness is clamped on four sides and while the film is stretched 1.28 times in a longitudinal axial direction at 165 deg.C by pulling the two clamps facing to each other. The spacing between the remaining two clamps facing to each other is gradually narrowed according to the stretching magnifications until the spacing is reduced to 0.89 times in a horizontal axis direction. The rate of reduction is 100-(1/square root of 1.28)X100X0.948= about 11%. The retardation value (R0) of the resulted phase difference plate is 543nm and the retardation value (R1) measured by rotation 45 deg. around the stretching axis is 494nm. The visual field angle characteristic value expressed by ¦R0-R1¦/R0X100 is 9. The liquid crystal display plate formed by using such phase difference plate is a black and white display which is white in the background color and black in the display part. This display plate is free from the coloration even when viewed from the diagonal direction and has the excellent visual field angle performance.