Method of manufacturing a birefringent film, optical film using the same, liquid crystal panel, liquid crystal display device and imaged display device

摘要

A method of manufacturing a birefringent film includes stretching a polymer film in a widthwise direction while at the same time shrinking the same in a lengthwise direction so as to satisfy the relational expression: (1/STD)^1/2≦SMD1, in which the length in the widthwise direction and the length in the lengthwise direction, of the polymer film before being stretched are respectively designated as 1, and STD represents a change ratio of the length in the widthwise direction of the polymer film due to stretching and SMD represents a change ratio of the length in the lengthwise direction of the polymer film due to shrinking, and make the stretched polymer film have an Nz coefficient of 0.9-1.1. This method achieves manufacturing of a birefringent film with a high production efficiency, while omitting the bowing phenomenon when manufacturing a birefringent film by stretching a polymer film in the widthwise direction, thereby limiting unevenness in birefringence, retardation and orientation angle and hence producing excellent optical characteristics, as well as achieving successive lamination when laminating with a polarizing film.