| 摘要 |
PURPOSE:To prevent a separative polarizing plate from being deteriorated when the temperature thereof rises because it absorbs infrared rays in a polarizing plate separation system overhead projector. CONSTITUTION:Light L1 from the light source 15 of a halogen lamp is made incident on a mirror Fresnel lens 12, reflected on it, condensed and projected on a screen by a projection lens 16. A liquid crystal panel 19 provided with a polarizing plate 24 only on one surface is arranged on the lens 12 by setting the plate 24 on the lens 12 side. Besides, the separative polarizing plate 25 which is paired with the polarizing plate 24 is arranged above the lens 16. Then, an image displayed on the panel 19 is expanded and projected on the screen. Besides, an infrared rays interruption filter 27 is arranged just under the lens 16 so as to prevent the temperature of the polarizing plate 25 from rising caused by the infrared rays. |
