| 摘要 |
PURPOSE:To reduce coloring of display and to improve the contrast by using an optical sheet made of a synthetic resin having a unique refraction characteristic to reduce the difference between the picture on a liquid crystal display device (LCD) viewed from the front and that viewed slantwise. CONSTITUTION:Boundary faces between the surfaces of a material 2 kept at a temperature higher than the glass transition temperature and lower than the melting point and inside faces of compression dies 1 are made lubricative, and the material 2 is compressed by compression dies 1 and is multiaxially orientated by plug flow and is cooled as it is to obtain a multiaxially orientated sheet 3. In this case, various elements are controlled to satisfy inequalities where (d), bmax, nmin, and n2 are the thickness, a maximum refractive index in each direction on a plane, a minimum refractive index, and the refractive index in the perpendicular direction of this sheet 3 respectively. When this optical sheet is used in the LCD, it eliminates the phase difference between the picture on the LCD viewed from the front and that viewed slantwise. |
