Abstract: A recording paper separating device for use in a copying machine, the device including a transfer charger for transferring a toner image from a photosensitive member onto a recording paper by discharge effected by a charging wire accommodated in a shield casing, a bias-loaded recording paper discharger, a transfer-power source, and a control for keeping a current supplied from the power source to the charging wire constant except for the current flowing through the recording paper discharger.

Abstract: A system includes an image forming apparatus or copier, and a central controller for remotely determining a cause of malfunction of the copier. The copier includes a control unit including a self-diagnostic portion; a selection portion for setting the control unit to a self-diagnosis mode; and a communication device for, when the self-diagnosis mode is set, connecting the control unit with a communication line. The self-diagnostic portion includes a receiving section for receiving diagnostic information through the communication device; a diagnostic section for executing self-diagnosis against the copier, on the basis of the received diagnostic information; and a transmitting section for transmitting the results of the self-diagnosis through the communication device.

Abstract: An automatic exposure control device for use in a copying machine in which a light source for illuminating the light to an original document is controlled based on the signal representing the light amount of the original document sensed by a light senses. There are two kinds of HIGH level limiter for limiting the upper limit of the power supplied to the light source. The HIGH level limiters are selected depending on whether the amount of light of the light source has been raised sufficiently or not, whereby over exposure copy or foggy copy can be prevented.