Contact location detecting mechanism of touch signal probe

A contact location detecting mechanism of a touch signal probe, the touch signal probe having a stylus support for moving in a three-dimensional space by a predetermined velocity vector according to an external command, a stylus holder mechanically connected to the stylus support, a stylus supported by the stylus holder and including a contact portion to be touched to a workpiece at a pointed end thereof, a vibrator provided to a part of the stylus holder for resonantly vibrating the stylus in an axial direction thereof, and a detector provided to a part of the stylus holder for detecting a change in vibration by the vibrator, the touch signal probe detecting the change in vibration by the detector when the contact portion touches the workpiece, the contact detecting mechanism of a touch signal probe detecting the contact location on the contact portion to the workpiece, comprising:

• a rotary motion generator for making a scanning rotary motion of the stylus on a plane orthogonal with an axis of the stylus by a predetermined radius and a predetermined angular velocity;
• a phase value detector for detecting phase value indicating a rotation position of the scanning rotary motion by the rotary motion generator;
• and
• a contact location detector for detecting the contact location of the contact portion to the workpiece based on a detection signal value detected by the detector and the phase value detected by the phase value detector while the contact portion touches the workpiece.