the first cleaning process after 15 seconds and thus fails to achieve the minimum cleaning time as a result this cleaning process does not register as a full cleaning and the target cleaning time for the subsequent second cleaning process is set to the standard cleaning time of 120 seconds the user terminates the second cleaning process after 105 seconds 15 seconds short of the target cleaning time which in this case is the standard cleaning time of 120 seconds the evaluation device 16 determines that the actual cleaning time fell short of the target cleaning time as a result the target cleaning time for the subsequent third cleaning process is set to 150 seconds i e the standard cleaning time of 120 seconds plus the fixed time of 30 seconds the user terminates the third cleaning process after 90 seconds the evaluation device 16 determines that the target cleaning time of 150 seconds was not reached and thus sets the target cleaning time for the subsequent fourth cleaning process to again be 150 seconds i e the standard cleaning time of 120 seconds plus the fixed time of 30 seconds the user terminates the fourth cleaning process after 135 seconds the evaluation device 16 once again determines that the target cleaning time of 150 seconds was not reached and thus sets the target cleaning time for the subsequent fifth cleaning process to again be 150 seconds i e the standard cleaning time of 120 seconds plus the fixed time of 30 seconds the user terminates the fifth cleaning process after 45 seconds.