Probe triggering

A work piece contact sensor (15) offers the touch trigger probe which belongs to the type which serves as a 動 seat (10) by a work piece contact stylus (12). Processor muP of the form of the PIC microcontroller in which a re-program is possible is used, and the signal from a work piece contact sensor (15) is monitored. When the (Ct) signal exceeds a threshold value during the continued period, processor muP sends out a trigger signal. The monitor of (Ct) may make it delayed during the period. When there is contact with work piece and there is a shock wave first, trigger operation can be made to start by this delay (Ci).