Patent ID: 8557047

Claim:
A method for preventing foreign matters from adhering in a dishwasher comprising: a first step for rotating a washing motor of a circulating pump in a first direction upon starting of a washing cycle, and sensing rotation speed of the washing motor at fixed intervals through a hole sensor; and a second step for controlling a rotation direction of the washing motor through a system controller according to the rotation speed of the washing motor sensed, wherein the second step includes the steps of: performing the washing cycle while maintaining the rotation direction of the washing motor in the first direction if a ratio of the rotation speed increase of the washing motor sensed is higher than a preset level; performing a foreign matter removal cycle to change both the rotation direction and the rotation speed of the washing motor for a preset time period if the ratio of the sensed rotation speed increase of the washing motor is lower than the preset level; sensing the rotation speed of the washing motor while rotating the washing motor in the first direction again, if the foreign matter removal cycle is finished; and performing the washing cycle while maintaining the rotation direction of the washing motor in the first direction, if the ratio of the rotation speed increase of the washing motor sensed after the foreign matter removal cycle is higher than the preset level, displaying an error state of the washing motor, if the rotation speed of the washing motor sensed after the foreign matter removal cycle is lower than the preset level, wherein the ratio of the rotation speed increase is variation of the rotation speed per unit time.