Patent ID: 8782837

Claim:
A control method of a washing machine, having a coupler coupled to a rotor of a drive motor when the coupler is in a downward position or coupled to a rotation prevention unit of a water tub when the coupler is in an upward position to selectively transmit power from the drive motor to a washing shaft or a spin-drying shaft, to perform a first mode in which the coupler is moved to the downward position to transmit the power to the washing shaft and the spin-drying shaft and a second mode in which the coupler is moved to the upward position to transmit the power to the washing shaft but not the spin-drying shaft, wherein the control method comprises: switching from the first mode to the second mode by moving the coupler upward, detecting that the coupler is abnormally coupled to the rotation prevention unit, moving the coupler downward so as to be coupled to the rotor, which corresponds with the first mode, rotating the drive motor to shake the coupler, and then moving the shaken coupler upward so as to be coupled to the rotation prevention unit, to thereby normally couple the rotation prevention unit to the coupler, which corresponds with the second mode; and switching from the second mode to the first mode by moving the coupler downward, detecting that the coupler is abnormally coupled to the rotor, moving the coupler upward so as to be coupled to the rotation prevention unit, which corresponds with the second mode, rotating the drive motor to shake the coupler, and then moving the shaken coupler downward so as to be coupled to the rotor, to thereby normally couple the rotor to the coupler, which corresponds with the first mode.