Patent ID: 7173720

Claim:
An image forming apparatus comprising: a plurality of processing circuits categorized into first and second blocks with respect to respective functions of the plurality of circuits; a power transformer having a plurality of secondary winding; a first power supply unit for always feeding DC current to the first block of processing circuits from at least one of the plurality of secondary windings; a second power supply unit for feeding DC current to the second block of processing circuits from the plurality of secondary windings other than the at least one of the plurality of secondary windings; at least one switch located between the plurality of secondary windings and the second block of processing circuits for interruption of power supply to the second block of processing circuits; a control unit for controlling the respective switch such that the DC current from the secondary windings to the second block of processing circuits is interrupted in a power save mode and the DC current is fed to the second block of processing circuits from the secondary windings in a normal mode; and a voltage converting circuit for converting DC voltage of the first power supply unit to DC voltage of another level such that the DC voltage of another level is fed to the second block processing circuits in the power save mode.