Patent ID: 11971567
Assignee: DAI NIPPON PRINTING CO., LTD.
Field: Optics (Instruments)
Classification: CPC G  H | IPC G

Claim 7:
8. The optical film according to claim 1, wherein the plastic film satisfies the following condition A:
when a sample of 50 mm in vertical×50 mm in horizontal in size is cut out from the plastic film; a total of five points are selected as measurement points, including 1 point at a center of the sample and 4 points at 10 mm from four corners of the sample toward the center; and
when slow axis directions at the five points of the sample are measured; and angles formed by any side of the sample with the slow axis direction at the measurement points are respectively defined as D1, D2, D3, D4, and D5, a difference between a maximum value of D1 to D5 and a minimum value of D1 to D5 is 1.5 degrees or more.