Method for cleaning a tub in a washing machine and a washing machine performing the same

A washing machine having a washing tub washing course provided thereto comprising:

• a washing tub;
• a washing water supply unit for supplying washing water to a washing tub;
• laundry amount sensing means for sensing a laundry amount in the washing tub;
• a driving unit for rotating the washing tub;
• a control panel having washing tub washing course selection means provided thereto for enabling to select a preset washing tub washing course;
• and
• a controller for performing the washing tub washing course following selection of the washing tub washing course through the control panel,
• wherein the washing tub washing course comprises:
• a detergent removing step for removing detergent from the washing tub, the detergent removing step comprises:
• a washing water supply step for supplying the washing water to the washing tub;
• a detergent washing step for moving the washing tub to make the washing water in the washing tub to move for washing the detergent from the washing tub;
• and
• a draining step for draining the washing water, wherein the draining step in the detergent removing step starts in the middle of the detergent washing step;
• a washing water supply step for supplying washing water to the washing tub;
• a laundry amount sensing step for sensing a laundry amount in the washing tub for determining whether to proceed to a next step or not;
• a soaking step for soaking dirt on a surface of the washing tub after applying the washing water to the dirt by moving the washing tub;
• and
• a washing step for washing the washing tub, if it is determined to proceed to the next step in the laundry amount sensing step.