A transition of an external enable signal generates a reset pulse to a counter to set the counter into a known state. The method described is particularly suitable for the processing of thermolabile and sensitive substances, since it can be performed in a manner very gentle to the product, and the wear on the devices used can be markedly decreased by reduction of the necessary cycle number or by reduction of the power density to be applied. The intepolating comparator compares an output signal from the primary comparator with a negative output signal from a primary comparator of another block of the plurality of blocks to generate a least significant bit. It is thus possible to regulate the displacement of the elastic body at low cost. The third nitride semiconductor layer has a thickness greater in a portion below the gate electrode than in a portion below the side of the gate electrode.