Reflecting type overhead projector with automatically variable safety illumination

摘要

In a reflecting type overhead projector having a light source lamp and a projection lens above a reflecting table formed of a Fresnel lens and a mirror upon which an original to be projected is laid, there is provided a control circuit which switches over supply of electric power to the light source lamp between full and part power supply according to whether the intensity of the light beams from the light source lamp received by a photosensitive element provided in the vicinity of the reflecting table is higher or lower than a predetermined value.