Abstract: An image forming apparatus includes a monochrome OPC drum, a color OPC drum, a charger, a developer, and a calculating portion. The charger charges a surface of a photosensitive layer of the color OPC drum. The developer performs development using a developing agent including a toner and a carrier. The calculating portion calculates a wear amount of the photosensitive layer of the color OPC drum. In addition, the charger charges the photosensitive layer of the color OPC drum during monochrome printing to a surface potential that suppresses toner adhesion and carrier adhesion to the color OPC drum. Further, the calculating portion calculates the wear amount of the photosensitive layer of the color OPC drum during monochrome printing to be less than during color printing.

Abstract: A code signal blanking apparatus comprising a switching means operative during a given period of a vertical blanking period of a television signal and a reference level setting means for producing an output of the reference level during said given period when the switching circuit is operative. A code signal is blanked by keeping a video signal level of the television signal at the reference level during said given period of the vertical blanking period of the television signal.

Abstract: A television signal discriminating apparatus adapted for use with the pay television system, which apparatus, for being compatible with the normal television system, monitors the television signal of received electric wave to detect whether it is from the pay television broadcasting station or the normal one and provides the correct video signal in accordance with the mode of modulation thereof.

Abstract: An AGC circuit comprises a video IF amplifier for receiving a amplitude-modulated broadcast wave of a video signal with a signal level having a constant amplitude added thereto, a means connected to the output of said amplifier for generating a video detection output signal of said broadcast wave, and a means connected to the output of said generating means for detecting said signal level from the video detection output signal and for generating an output signal representing the signal level during the existing period of the signal level. The output signal representing the signal level is applied to the video IF amplifier and is used as a biasing signal of the amplifier. The signal level having a constant amplitude is a gray level existing intermediate between a black level and a white level.