| 摘要 |
<p>Red, green and glue light beams from light source portions (301, 302, 303) are modulated respectively by light valve units (317, 319, 321) of a light valve portion (304) and enter a color combination optical system (305). The color combination optical system (305) includes three triangular prisms (325, 326, 327), each having a vertex angle of about 30 degrees, and is formed by joining the prisms together with dichroic mirror surfaces (328, 329) interposed therebetween. The respective light beams entering the planes of the prisms opposite to their vertex angles are combined in the color combination optical system (305) and emitted from an exit plane of the prism (327). The optical path lengths of the respective light beams between the incidence planes and the exit plane (332) are substantially equal to one another. Then, a projection lens (306) magnifies and projects the combined light beam onto a screen. This configuration can increase the quality of projection images and reduce the size and cost of the apparatus. <IMAGE></p> |
