Patent ID: 6367020
Filing Date: 2002-04-02
Classification: G06F,Y10S

Abstract:
A system for controlling the operating mode of a computer, the system comprising:a proximity sensor comprising an ultrasound sensor for detecting whether a person is located proximate the computer without need for the person to wear an extraneous device for the proximity sensor to detect the person, the proximity sensor generating a detection signal indicative of the person leaving the proximity of the computer; and a control circuit coupled to the proximity sensor and the computer, the control circuit switching the computer to a password protected operating mode responsive to the detection signal, the control circuit including a signal conditioning unit coupled to the proximity sensor that receives a relatively low frequency signal from the proximity sensor indicative of a frequency difference between an acoustic signal from the proximity sensor and a reflected acoustic signal, the signal conditioning unit converting the relatively low frequency signal to a conditioned signal having a magnitude indicative of the amplitude of the relatively low frequency signal; and a threshold detection circuit coupled to the signal conditioning unit that receives the conditioned signal and switches the computer to the password protected operating mode when the conditioned signal satisfies a predetermined threshold.