Abstract: A reader-printer has a first mirror rotatable to a first position in which it is capable of forming a reader optical path for projecting an image light onto a screen and a second position in which it is capable of forming a printer optical path for projecting the image light onto a photosensitive surface, a second mirror disposed in the reader optical path for disposed in the reader optical path for directing the light from the first mirror to the screen, a third mirror disposed in the printer optical path for directing the light from the first mirror to the photosensitive surface, a driving device for rotating the first mirror to the first position and the second position, and a detecting device disposed outside the reader optical path and the printer optical path for receiving the reflected light from the first mirror during the rotation of the first mirror and detecting the image density.

Abstract: A reader printer includes a rotatable scanning mirror disposed in an optical path formed between a projection lens and a printer section in correspondence with a printer mode, the scanning mirror being rotated to perform scanning of an image and a movable mirror disposed near such a printer mode optical path for movement between an inserted position where it is inserted in the optical path and a retracted position to which it is retracted from the optical path. Movement of the movable mirror causes mutual switching between the printer mode optical path and the reader mode optical path.

Abstract: An image forming apparatus which is capable of forming a positive image either from a negative original or a positive original. The apparatus is provided with a device for preventing the non-image area of the photosensitive member from being developed by a developer, so as to avoid a wastefull consumption of the developer. The operation of the preventing means is controlled in dependence on whether the original is positive or negative, so that the prevention of the non-image area development is effectively performed independently of whether the original is negative or positive.