| 摘要 |
<p>The contrast of an LCD cell (12) is enhanced by the use of a gradient index plate mirror (16',16'') positioned behind the cell to reflect light from a light source (14',14'') through the cell in a well-collimated beam. The mirror (16',16'') is formed of an optical plate (34',34'') having first and second major surfaces (36',36'') and (38',38''), the latter having a reflective coating (40',40'') thereon. The optical plate (34',34'') has a gradient index of refraction which increases from its first to its second major surface. As a consequence, the light entering the plate and reflected back therethrough is refracted so as to be bent closer to the plate normal (42',42''), causing the light leaving the mirror and entering the LCD cell to be well collimated, which is desirable for improving the display contrast. <IMAGE></p> |
