This document discusses among other things, methods and apparatus to conserve energy when providing proximity information. An example apparatus can include an energy emitter configured to emit a first pulse of energy, an energy sensor configured to receive reflected energy from the first pulse of energy, a control circuit including a processor, the processor configured to provide first proximity information of the apparatus with respect to an object using the reflected energy. The control circuit can be configured to control the energy emitter, to compare the first proximity information with second proximity information, and to modulate a delay between the first pulse of energy and a subsequent pulse of energy using the comparison.

The embodiments of the present disclosure provide a touch sensor device. The touch sensor device comprises a housing, configured to provide a touch region; and at least one sensor, configured to be fixed near the touch region. The at least one sensor includes: a signal transmitting unit, configured to generate a vibration signal under the action of an excitation signal; a signal receiving unit, configured to receive the vibration signal and generate an output signal; and a processor, configured to recognize a touch operation performed on the touch region according to the output signal.

A control device for a power switch, a control method for the power switch, and an electronic display system are provided. The control device includes an acoustic sensor and a switch. The switch is coupled between a power supply and an external electronic device. The acoustic sensor senses an acoustic signal. In a standby mode, the acoustic sensor generates a switch control signal according to a frequency of the acoustic signal. The switch turns on or turns off a path for the external electronic device to receive power according to the switch control signal. In the standby mode, the acoustic sensor periodically and actively performs a generating operation of the switch control signal.

Provided is a refrigerator. The refrigerator is characterized by enabling at least a part of a refrigerator door to be selectively transparent by a user's operation, such that the user sees through an inside of the refrigerator while the refrigerator door is closed.