| 摘要 |
A birefringent film with excellent uniformity in in-plane retardation, retardation in the thickness direction, and alignment axis is provided. The birefringent film is produced in such a manner that, in the step of stretching a polymer film, the polymer film is stretched in a width direction while being shrunk in a longitudinal direction, and assuming that lengths in the width direction and the longitudinal direction of the polymer film before being stretched are 1, a change ratio (STD) of the length in the width direction of the polymer film resulting from the stretching and a change ratio (SMD) of the length in the longitudinal direction of the polymer film resulting from the shrinking satisfy the following formula (1). (1/STD)1/2≰SMD<1 (1) |
