Abstract: A copying or printing machine comprises a microcomputer including a random access memory in which a set of coded signals may be written in and read out, a read-only memory having a sequence control for accomplishing printing or copying operation, and a processing unit operative to reproduce a copy of an original. The machine is provided with a first developing device devoted to colored development and an alternately-used second developing device devoted to black development. If the interrupt copying mode is set up during a copying run, copying conditions for the copying run are stored in the RAM, and the interrupt copying run is allowed. In that case, irrespective of copying conditions of the previous copying run, the interrupt copying mode permits the second developing device to be automatically selected. Upon the termination of the interrupt copying run, copying conditions for the previous copying run are read from the RAM, to permit the run to be completed.

Abstract: There is provided a copying machine in which a copying magnification and a copying density are variable. When the operation mode is set in the check mode and a copying start key is depressed, a document is copied once at a predetermined copying magnification or copying density. Thereafter, the copying magnification or the copying density is automatically changed, and the copying operation of the document is performed again. The above-mentioned operation is repeated until the copying operations at all the copying magnifications or the copying densities are completed.

Abstract: A return speed control system for use in a document scanning apparatus with a moving means moving relative to the document for optical scanning, comprising first and second detecting means and a control means. When the moving means is moving a backward, the first means detects the arrival of the moving means at a first position or an initialize position. When the moving means is in the backward motion, the second detecting means detects the arrival of the moving means at a second position separated by a predetermined distance from, the first position in the scanning direction. According to the operating state of the document scanning apparatus and the results of the detection by the first and second detecting means, the control means selectively sets up a high-speed backward mode, a low-speed backward mode, or a stop mode in the moving means.

Abstract: The invention provides an image forming apparatus having a control device to control a fixer and a paper conveyor system to perform preheating of the fixer and driving of the conveyor system for a predetermined time interval immediately after power is supplied, to stop the fixer and the conveyor system when preheating of the fixer is completed before the predetermined time interval has elapsed, and to continue operation of the conveyor system when a paper sheet is jammed in the paper conveyor system, even if preheating of the fixing means is completed before the predetermined time interval has elapsed.