Abstract: An electrophotographic reproducing machine wherein an integrally formed dish-like housing for an exposure optical system is mounted onto a machine frame which accommodates therein a plurality of process units for reproducing and is opened upward, and a document glass plate is mounted at the top portion of the housing for the exposure optical system through glass mounting plates. The housing accommodates therein a slit plate for scanning of an exposure lamp, a projection lens, which is formed in its peripheral walls with vent holes for promoting ventilation within the machine and which has at its bottom portion a shield bottom wall serving as also a heat insulating plate. Guide rail surfaces for guiding movable mounts of the optical system are formed on both side walls of the housing opposite to each other.

Abstract: In a copying machine in which the distance of projection scanning is varied by relative movement between the copy board and the optical system in accordance with the size of the original, indices are provided on the copy board for positioning the original so that the shorter side of the original always corresponds to the direction of scanning. This unification of original placement results not only in a shortening in the distance of the projection scanning but an increase in copying speed.

Abstract: An electrophotographic reproducing apparatus in which a reproducing apparatus body unit including an electrostatic latent image receptor such as a photosensitive member and other electrophotographic treating device is assembled in advance whereas an optical scanning unit including at least a document illumination lamp, a group of mirrors and a group of focusing lenses is assembled in advance in a predetermined positional relationship to the reproducing apparatus body unit, and both the units thus assembled are jointed at predetermined reference planes to each other and so integrated that they can be driven cooperatively with each other. Said two units further include jointing device at their respective predetermined reference planes.

Abstract: In a transfer type electrophotographic copying apparatus having a rotatable photosensitive drum for receiving an electrostatic latent image of an original and a heating device comprising a heating roller and a pressure-contact roller rotatable in a condition of pressure-contact with the heating roller for fixing a toner image of the original on a transfer paper moved along a path including a position of image transfer contact with the drum and then between the rollers, the distance from the contact position of the transfer paper with the drum to the pressure-contact point of the heating and pressure-contact rollers being less than the length of the transfer paper as measured in the direction of movement of the paper along the path.