Foldable mobile telephone

Abstract

A foldable mobile telephone which is constituted of a main body and a lid being open/close-able and is able to detect open/close state of the lid is provided. The main body provides a receiver for ultrasonic wave and the lid provides a microphone for ultrasonic wave. An ultrasonic oscillator intermittently generates an ultrasonic signal at each fixed interval and gives the ultrasonic signal to the receiver for ultrasonic wave. The receiver for ultrasonic wave receives the ultrasonic signal from the ultrasonic oscillator and generates an ultrasonic wave. The microphone for ultrasonic wave receives the ultrasonic wave generated by the receiver for ultrasonic wave and generates an ultrasonic detecting signal. An ultrasonic level judging circuit receives the ultrasonic detecting signal from the microphone for ultrasonic wave and judges whether the level of this ultrasonic detecting signal is higher or lower than a decided level and judges the open/close state of the lid and generates a judging signal. With this construction, the detecting the open/close state of the lid becomes possible and the ultrasonic wave is applied for this constitution, therefore the outside magnetic field does not influence this operation.