| 摘要 |
PURPOSE:To eliminate erroneous detection to detect the change of a zero-cross frequency due to system switching and the like as the generation of single operation when the change is large by excluding the longest and the shortest data and seeking an average frequency from the remaining data from the measuring data of zero-cross intervals of appropriate number of times before a certain time point. CONSTITUTION:The measuring data t1, t2...tn of zero-cross intervals of a current time point to past n times are collected (Step S1), Next, the maximum value tmax and the minimum value tmin are extracted from the collected n-pieces of measuring data (S2). Next, the average frequency fn-2 according to n-2 pieces of the measuring data and the average frequency fm-2 according to m-2 pieces of the measuring data which are smaller than n-2 pieces are computed by performing predetermined calculation of n-2 pieces of the measuring data excluding the extracted maximum tmax and minimum tmin (S3). gamma=fn-2/fm-2 is computed (S4), and when gamma>a or gamma<b (a and b are set values) (S5), it is detected as the state of single operation and a predetermined processing is performed. |
