Patent ID: 8583075

Claim:
A power supply control apparatus, adapted to a communication device, comprising: a power switch, coupled to a power supply, for controlling the flow of power from the power supply to the communication device; and a signal detecting unit, for detecting a wireless signal via electromagnetic induction to generate a detection signal for controlling the switch to determine whether to provide power to the communication device from the power supply, comprising: a coil antenna, for detecting whether the wireless signal is received via electromagnetic induction and converting the wireless signal to an alternating current (AC) signal via electromagnetic induction; a signal converting unit, for converting the AC signal to a direct current (DC) signal; a filter unit, comprising a filter capacitor, for removing ripple of the DC signal and generating the detection signal when the filter capacitor is charged; a ground switch, connected to ground; a discharge indicating circuit, comprising: a rectifier, for detecting whether the wireless signal is received via the coil antenna; a discharge capacitor, for storing power received from the rectifier; and a discharge unit, for discharging power stored in the discharge capacitor to a predetermined extent; wherein the filter capacitor and the discharge capacitor are coupled to the ground switch; wherein an indicating signal activates the ground switch to connect to ground when power stored in the discharge capacitor is completely discharged by the discharge unit, causing the filter capacitor to discharge; wherein the power switch is controlled by a logical OR gate receiving input signals from a controlling unit controlled by a user operating a user interface, and the signal detecting unit.