| 摘要 |
PURPOSE: To obtain a phase difference plate having excellent phase difference compensation performance uniformly over approximately the entire area of a film by specifying the difference in the thicknesses of the adjacent thick parts and thin parts of the unstretched film and uniaxially or biaxially stretching a raw sheet having the waveform fluctuations of pitches of a specific range. CONSTITUTION: The raw sheet in which the change in the thickness of the unstretched film has the fine waveform-like fluctuations in both of its longitudinal direction and transverse direction and in which the differences in the thicknesses between the adjacent thick parts and thin parts is >=0.5 to <=3μm and the pitches thereof are >=1 to <=40μm is uniaxially or biaxially stretched. As a result, the phase difference plate which has a uniform retardation value and of which the difference in the retardation values between arbitrary two points apart 10cm from each other within the film plane is <=5nm in such a case and which does not generate unequal colors is obtd. Namely, the phase difference plate having uniform Δn (refractive index anisotropy) of the retardation value (Δn×d) is obtd. and, therefore, the retardation value uniform over the entire part is obtd. in spite of the presence of the fine fluctuations in (d) (film thickness). |
