| 摘要 |
PURPOSE:To improve the utilization rate of a light beam and to improve orientation performance by collimating a light beam from a light source into parallel light through a convex lens and deflecting the parallel light optically to a body to be illuminated by a prism which has slanting prism array surfaces. CONSTITUTION:The light from the light source 11 at the focus position of a convex lens 20 is made into the parallel light 242 and totally reflected light 243 generated by a slanting prism array surface 22 of a photoconductor 21 is made into diffused light 244 by a light scattering surface 23 to illuminate a liquid crystal panel 17. The angle theta of the array surface 22 to the optical axis of the parallel light 242 is set to <=45 deg. and the pitch of the array is set below the picture element pitch of the liquid crystal panel; and the array surface is positioned opposite picture elements of the panel and then the largest quantity of transmitted light is obtained in a picture element opening state to obtain a high-contrast image plane. Thus, the utilization rate of the light beam is improved and the light beam which is oriented excellently is obtained. |
