| 摘要 |
PROBLEM TO BE SOLVED: To provide an image projecting device which is made small-sized and inexpensive by shortening the back focus of a projection lens and simplifying a heat radiating structure. SOLUTION: This device is equipped with a light polarizing element which polarizes illumination light guided from a light source selectively to the direction of one of ON light and OFF light according to the shading of video, a projecting means which projects the ON light on a screen, and a prism assembly which is arranged between the optical paths of the light polarizing means and projecting means, the prism assembly has an air gap which transmits the ON light and totally reflects the OFF light, and a prism on the side of the total reflection of the OFF light among prisms facing the air gap has such a thin wedgelike shape that at least part of the OFF light is totally reflected more than once between an air-gap side surface and an opposite surface.
|
