Patent ID: 7428830

Claim:
A washing machine comprising: a rotary drum having a substantially horizontal or slanted rotational axis, for accommodating laundry therein; a water tub movably supported in a washing machine main body, for accommodating the rotary drum therein rotatably; a supporting metallic part for supporting the water tub; a washing machine base for supporting the washing machine main body; a motor for rotating the rotary drum; a controller for controlling the motor; and a vibration detecting unit disposed between the supporting metallic part and the washing machine base, for detecting a vibration of the water tub, wherein the vibration detecting unit includes a differential transformer having a magnetic body, an input primary coil, and two output secondary coils disposed to be coaxial to the input primary coil, wherein the magnetic body is shaft-shaped and is movably disposed to pass through the three coils, wherein the two secondary coils generate respective voltage outputs of the vibration detecting unit in response to a constant input to the primary coil and a displacement of the magnetic body due to a movement thereof, and wherein the slopes of the respective voltage outputs of the two secondary coils per a unit displacement of the magnetic body are different from each other.