Patent ID: 7873295

Claim:
An image forming system in which an image forming apparatus and an external controller are connected to each other via a network, wherein the image forming apparatus includes a power supply unit that supplies power to the image forming apparatus, the external controller includes an energy-saving control unit that detects a supply of power to the image forming apparatus by the power supply unit and performs an energy saving control of the external controller based on a detection of the supply of power to the image forming apparatus, and a switching unit that switches a start and a stop of supply of power to an onboard circuit of the external controller, upon detecting the supply of power to the image forming apparatus by the power supply unit, the energy-saving control unit sends a power control signal for instructing a start of the supply of power to the onboard circuit to the switching unit, and upon receiving the power control signal, the switching unit switches to the start of the supply of power to the onboard circuit.