JPS5458465A - Washing machine - Google Patents

Abstract

PURPOSE:To detect the water level easily and accurately without making contact with water by making the level detecting wall of a washing tub having a drain hole at the upper end thereof with nearly transparent material and providing photo detector and light emitting devices on the outside, irrespective of the condition such as under rotating or not. CONSTITUTION:In a washing tub 7 having a drain hole provided at the upper end thereof, the level detecting wall is made of nearly transparent material. The radiation light from a light emitting device 20 provided on the outside is reflected from the level detecting wall of washing tube 7 being not in contact with water, and is not reflected from the level detecting wall being in contact with wall to be penetrated into the wall. Therefore, when the reflected light of the light emitting device 20 from the level detecting wall is received by photo detectors 21, 22 equipped with hoods 24, 25, which are connected with a differential amplifier 23, the water level in the washing tub may be accurately detected without making contact irrespective of the condition such as under rotating or not. Besides, by lining the entire circumference of inner wall of the level detecting part of the washing tub with prism-like protrusion in a form of a band, the incident light is total-reflected, so that the precision of level detection may be enhanced.