1.  Field of the Invention
The present invention relates to a washing machine and a control method thereof, and, more particularly, to a washing machine and a control method thereof which senses an unbalance condition occurring during a spin-dry cycle. 
2.  Description of the Related Art
In conventional washing machines, an unbalance condition of a rotating tub is sensed during an operation of a motor coupled to the rotating tub to spin-dry laundry.  When an unbalance condition of the rotating tub is sensed, the motor is repeatedly driven and stopped until the unbalance condition of the rotating tub is not sensed.  When the unbalance condition of the rotating tub is not sensed, the motor is continuously driven so that a speed thereof reaches a predetermined spin-dry speed. 
In the conventional washing machines, the sensing of the unbalance condition is performed in a state in which laundry contained in the rotating tub is wrapped on an inner peripheral surface of the rotating tub such that the laundry is in constant contact with the inner peripheral surface of the rotating tub in accordance with a rotation of the rotating tub. 
However, the conventional washing machines have problems in that the wrapped state of the laundry is not uniform because the motor is driven at a constant speed to wrap the laundry without taking into consideration the weight of the laundry.  When a small amount of laundry is wrapped, the driving and stopping of the motor should be repeated several times until the unbalance condition of the rotating tub is completely eliminated.  However, when a large amount of laundry is wrapped, a possibility that the unbalance condition occurs is greatly reduced.  In this case, abnormal vibrations and noise may be caused by even an unbalance condition of the rotating tub, which is undetectably small, when a rotating speed of the rotating tub reaches a speed, at which resonance occurs.