Acoustic proximity detection for computers with reduced power consumption

A proximity detection system of an electronic device, the proximity detection system comprising:

• at least two transducer units being capable of transmitting acoustic signals identifying the transducer unit within a predetermined frequency range, the at least two transducer units being positioned at a distance from each other in the electronic device, and at least one receiving transducer being capable of receiving acoustic signals within the frequency range reflected from an object;
• wherein the proximity detection system is configured to recognize the transducer identification and to measure the distance between each transducer unit and the reflecting object based on the transmitted and received signals based on the measured propagation time of the received reflected signal;
• wherein the proximity detection system is configured to activate each of the transducer units in a predetermined time sequence and compare the measured distance from each transducer unit to the reflecting object, thus calculating the direction to the reflecting object, and at the detection of the object within a predetermined range of directions providing an activation signal to the electronic device;
• wherein the transducer units are activated in an alternating sequence, the identification being defined by the sequence;
• and
• wherein the proximity detection system is configured to activate the predetermined features of the electronic device when the distance and direction is within predetermined limits.