LIGHT DIFFUSING LENS SHEET, DIRECT BACKLIGHT USING THE SHEET, AND LIQUID CRYSTAL DISPLAY TELEVISION HAVING THE BACKLIGHT INSTALLED THEREIN

摘要

A light diffusing lens sheet having a lens surface and a groove/ridge structure surface. In the lens sheet, a large number of substantially triangular column shaped prism sections made of a transparent high polymer material are arranged on the lens surface at specified intervals such that the major axes of the triangular columns are generally parallel to each other and, further, a groove/ridge structure having a height difference A of 2 - 30 µm, an interval B of 50 - 1000 µm, and B/A of 10 - 50 is formed on the groove/ridge surface at a twisting angle of 5 - 30° relative to the major axes of the prism sections. The light diffusing lens sheet has high light use efficiency, allows a user to easily view a display screen from the front, makes a place where a light source is placed less visible from the user, suppresses occurrence of interference fringes, and can emit uniform light from the entire emitting surface. Also, because the number of parts of the backlight can be reduced, the lens sheet can be manufactured at low cost and with high productivity.