| 摘要 |
PURPOSE:To erase easily a projected image on a screen at an original replacement time with the operation of a shutter by arranging the shutter, which intercepts selectively the light passing a projecting optical system, near this optical system. CONSTITUTION:A shutter 7 is constituted of a frame body 8 formed to, for example, a rectangular shape and a light shielding plate 10 which is arranged freely slidably in this frame body 8 and to which a grip 9 is fixed. In case that an original 11 is projected, the light shielding plate 10 is pulled and is set to a position off a lens 4, and the original 11 is placed on an original placing table 3. When a light source 2 is switched on, a transmission image of the original 11 illuminated by this light source 2 is focused and projected on a screen 12 by a projecting optical system 6. In case of replacement of the original 11, the grip 9 is operated to pull the light shielding plate 10 to set it in a position between the lens 4 and the original 11. Then, the light from the light source 2 is intercepted by the light shielding plate 10 and is not made incident on the projecting optical system 6, and the original image is not projected onto the screen 12. |
