| 摘要 |
<p>A back projection display has a reflecting means 7 which reflects image light from an image projector 4 toward the back side of a diffusion screen 3, a light separating means 8 which is provided on the back side of the diffusion screen 3 and reflects the image light toward the reflecting means 4, and a 1st reflecting mirror 6 which is a total reflecting mirror. The reflecting means 4 is composed of a 2nd reflecting mirror 72 which is a total reflecting mirror and a 1/4-wavelength plate 71 and reflects the incident image light with 90 DEG polarization. The light separating means 8 is composed of a plane-polarization mirror and transmits P-wave polarized light only and reflects light of other polarization. If P-wave image light is emitted from the image projector 4, the light is changed to S-wave image light by the reflecting means. Therefore, the image light traveling toward the screen 3 is reflected from the light separating means 8 and travels toward the reflecting means 4 again. As the image light is subjected to further 90 DEG polarization by the reflecting means, the light is changed to P-wave polarized light and travels toward the screen 3. As the separating means 8 transmits the P-wave polarized light, the image light is transmitted by the separating means 8 and reaches the screen 3. As the reflection is repeated a plurality of times between the reflecting means 4 and the light separating means, a long optical path can be obtained even if the display is thin. <IMAGE></p> |
