Patent attributes
Contact sensing probe apparatus includes a workpiece contacting stylus, a transducer mechanically coupled to the stylus and an oscillator for supplying an alternating current to the transducer to induce vibration of the stylus. A contact sensor is also provided for monitoring the phase difference between the voltage supplied to the transducer and the current flow to the transducer. The oscillator is arranged to supply the transducer with an alternating current of a first frequency during contact sensing. This first frequency is selected to induce mechanical resonance but to be away from the maximum of the mechanical resonance peak. The probe may be used with co-ordinate positioning machines, such as portable articulated measuring arms, co-ordinate measuring machines (CMM) and the like.
