Abstract: An image forming apparatus wherein a recording medium stored in a storage device is first detected by a detection device and the recording medium is abutted against a second paper feed roller, the second paper feed roller being driven by a controller for feeding the abutted recording medium to an image forming unit, at the timing at which the tip of an image in the image forming unit is in accord with the tip of the recording medium for each of the size of the recording medium.

Abstract: An image forming apparatus wherein a recording medium stored in a storage device is first detected by a detection device and the recording medium is abutted against a second paper feed roller, the second paper feed roller being driven by a controller for feeding the abutted recording medium to an image forming unit, at the timing at which the tip of an image in the image forming unit is in accord with the tip of the recording medium for each of the size of the recording medium.

Abstract: An image density reading apparatus in which an image of a document is irradiated by a light source and a density signal is generated from an image light reflected from the image. In the apparatus, there is an amplifier for amplifying a density signal on the basis of an amplifying gain and a signal processor for processing the amplified density signal in accordance with a predetermined processing algorithm to output a gain control signal. The amplifier is provided with a switch for changing a gain in response to the gain control signal.

Abstract: A braking system for image forming apparatus returns an optical scan system in the image forming apparatus to a preselected home position after each scan of a document placed on a platen, within a predetermined period of time. Various factors including temperature, the number of copies of the document previously made, can change the operating performance of the braking system so that it does not return the optical scan system to the home position within the predetermined period. Detectors are provided to detect and sense the factors which will change the operating performance of the braking system. Brake control apparatus is responsive to the detectors and controls the braking system to return the optical scan system to its home position within the preselected period of time to thereby maintain the efficiency of the braking system even as the factors such as temperature, and number of copies previously made changes during operation of the image forming apparatus.

Abstract: A temperature controller wherein breakage of a thermistor whose resistance decreases with increase in temperature of a member to be heated is detected by watching whether a voltage dependent upon the resistance of the thermistor is increased or not after a predetermined period of time. A heater for heating the member is turned off when the breakage of the thermistor is detected.

Abstract: The invention provides an image forming apparatus capable of performing an ordinary copy mode, whereby the entire surface of a document is scanned by an image reader to copy the entire surface on a copy sheet, and a serial page copy mode, whereby first and second half portions of the document are separately scanned to copy each half portion on a separate copy sheet. In the apparatus, copy sheets of different sizes are fed from a plurality of cassettes each storing a copy sheet of a predetermined size or a manual feed tray. There is provided a memory for memorizing a serial copy sheet size to be fed from the manual feed tray. When the serial page copy mode is selected in the manual feed mode, the image reader is controlled to separately scan the first and second half portions of the document on the basis of the serial copy sheet size.

Abstract: A copying apparatus includes a copy condition setting unit for setting copy conditions such as a copy count, a copy density, and a magnification. A standard mode setting unit initially sets the copy conditions upon starting of the apparatus to predetermined initial values, and a frequency calculating unit calculates a setting frequency of each copy condition set by the copy condition setting unit and the standard mode setting unit. When the frequency calculated by the frequency calculating unit exceeds a predetermined value, a correction unit corrects the corresponding copy condition to have the initial value set by the standard mode setting unit.

Abstract: A power source for a developing bias comprises an input power source, a standard voltage generating means which generates standard voltage employing the input power source, a pulse transformer on which the standard voltages are impressed as a direct current voltage to be switched on and off, clock pulse generating means which generates clock pulses with a fixed cycle and fixed duty ratio, and switching means driven by the clock pulses for switching the pulse transformer to provide a regulated output voltage. The circuit of the invention eliminates the need for a feedback loop to compensate for load variations.