Power source and image forming apparatus

A power source which includes a first power source unit that applies a first operating voltage to a control unit and a second power source unit that applies a second operating voltage to a unit to be controlled by the control unit, comprising:

• a first electric power supplying unit that supplies electric power to the first power source unit;
• and
• a second electric power supplying unit that supplies the electric power to the second power source unit;
• wherein
• the first electric power supplying unit includes a parallel circuit composed of a main power switch and a first switching unit capable of being electrically controlled;
• the second electric power supplying unit includes the main power switch;
• the electric power is simultaneously supplied to the first power source unit and the second power source unit when the main power switch is turned on;
• and
• the first switching unit is turned on by a voltage output from the second power source unit.

A power source which includes a first power source unit that applies a first operating voltage to a control unit and a second power source unit that applies a second operating voltage to a unit to be controlled by the control unit, comprising:

• a first electric power supplying unit that supplies electric power to the first power source unit;
• and
• a second electric power supplying unit that supplies the electric power to the second power source unit;
• wherein
• the first electric power supplying unit includes a main power switch;
• the second electric power supplying unit includes a series circuit composed of the main power switch and a second switching unit capable of being electrically controlled;
• and
• the electric power is supplied to the first power source unit by turning on the main power switch, and the electric power is supplied to the second power source unit by turning on the second switching unit by a voltage output from the first power source unit.