wiping processes in the direct activation mode this is similar to the method claimed in claim 6 but involves a simple averaging over all 34 d i 34 during the direct activation mode then the clock or time counter is set to zero t 0 fig6 a and the rain sensor 12 begins the intermittent operation mode in this operation mode the following times are continuously measured and actualized the actual clock time t the wiping process durations t and the d i time intervals from a wiping process to the next s i are measured in the program section in which the time to the next s i is measured a comparison between the actual counter time t and the product of the constant c 1 and the actual interval time i 0 occurs if the actual counter time t is larger than this product the actual counter time is stored and an s i value is no longer expected the actual interval time i 0 is placed in a program loop which means that a new calculated value always replaces the old or previous value value and the desired number of past i values is always available further the previous i 0 value is designated as the value i 1 when a signal s i is generated by the rain sensor 12 see the first decision block in fig6 b and the.