An electronic apparatus includes an outer case, and a piezoelectric element mounted to an inner surface of the outer case and configured to impart vibration to the outer case due to deformation in correspondence with an applied voltage and to generate a voltage corresponding to deformation due to a shock imparted to the outer case. An induction element applies an increased voltage to the piezoelectric element, a first switch performs control as to whether or not to supply an electric current from a power source to the induction element, a second switch effects connection or disconnection between the induction element and the piezoelectric element, and a shock detection unit to detects a shock imparted to the outer case based on the voltage generated in the piezoelectric element.

An electronic apparatus includes an outer case, and a piezoelectric element mounted to an inner surface of the outer case and configured to impart vibration to the outer case due to deformation in correspondence with an applied voltage and to generate a voltage corresponding to deformation due to a shock imparted to the outer case. An induction element applies an increased voltage to the piezoelectric element, a first switch performs control as to whether or not to supply an electric current from a power source to the induction element, a second switch effects connection or disconnection between the induction element and the piezoelectric element, and a shock detection unit to detects a shock imparted to the outer case based on the voltage generated in the piezoelectric element.

A personal alarm system including a sound-detecting transmitter and a pressure-detecting receiver capable of generating a local stimulus generated by the receiver and at the receiver's location once a signal indicative of a detected sound is transmitted from the transmitter to the receiver while the receiver is detecting whether or not pressure is present.