Patent ID: 7761718

Claim:
A power controller that controls supply of power from an external source to a process circuit, the power controller comprising: an accumulating unit that accumulates power that is supplied from the external source; and a controller that causes, when the power of the external source is insufficient to drive the process circuit, the accumulating unit to supply accumulated power to the process circuit, wherein the controller includes: a switching unit that is connected to the external source and the process circuit and switches to enable or to disable the power supply from the external source to the process circuit; and a constant potential circuit that is connected to the accumulating unit and the process circuit such that the constant potential circuit fixedly maintains, regardless of whether the switching unit switches to enable or to disable the power supply, a potential necessary for the process circuit, and wherein the constant potential circuit includes: a comparing unit that compares, when only the power from the external source is being supplied to the process circuit, a threshold value, which is substantially same as a potential necessary to operate the process circuit, with an actual potential of the process circuit; and a power distribution controller that distributes, upon a result of comparison by the comparing unit indicating that the actual potential is greater than the threshold value, power from the accumulating unit to the process circuit.