Load detecting system and automatic washing machine equipped with the system

Abstract

The invention provides a load detecting system comprising a core () of magnetostrictive material, a coil () disposed in the vicinity of the core, and a load detecting circuit () connected to the coil () for detecting the magnitude of a load acting on the core (). The load detecting circuit () comprises an exciting circuit () for passing an a.c. detecting current through the coil (), a pulse current generating circuit () for passing through the coil a detection preparing current having a current value greater than the maximum value of the detecting current, a change-over circuit () for effecting a change-over between the exciting circuit () and the pulse current generating circuit () to pass the detecting current through the coil after passing the detection preparing current therethrough, and a microcomputer () for deriving the magnitude of the load acting on the magnetostrictive element based on an impedance variation produced in the coil during the period of passage of the detecting current through the coil.