Patent ID: 7530243

Claim:
A drum type washing machine comprising: a housing; a rotary drum for accommodating therein laundry, the rotary drum having a substantially horizontal or slanted rotational axis; a water tub, suspended in the housing, for accommodating therein the rotary drum; a controller for controlling an operation of the washing machine; and a displacement detecting unit disposed between the water tub and a base portion of the housing, for detecting displacement of the water tub, the displacement detecting unit including: a primary coil wound around a bobbin; a first secondary coil without overlapping the primary coil and a second secondary coil overlapping the primary coil, the first and the second secondary coil being wound coaxially with the primary coil; and a magnetic body vertically movable inside a bobbin corresponding to a displacement of the water tub, wherein the displacement detecting unit is configured such that a signal output generated by the first and the second secondary coils varies corresponding to a displacement of the magnetic body with respect to a triggered magnetic signal transmitted to the primary coil, and a voltage change of the first secondary coil in response to displacement of the magnetic body is greater than that of the second secondary coil, the voltage being obtained by processing the signal output.