US Patent 10083579 Electronic device and method for controlling electronic device

An electronic device including a submersion detector, an illuminant provided inside a casing, a lighting circuit, a controller, an unnecessary part that is unnecessary for lighting the illuminant. The submersion detector detects submersion of the electronic device and retrieval of the device. The submersion means that the electronic device falls onto or into water. The retrieval means that the electronic device is retrieved from water. The lighting circuit lights the illuminant in response to an input of a lighting signal. The controller lights the illuminant by generating and outputting the lighting signal to the lighting circuit for a period of time from the submersion at least until the retrieval. In a case where the unnecessary part is supplied with power when the submersion detector detects the submersion, the controller stops the supply of the power to the unnecessary part at least for the above period of time.