Patent ID: 6481939
Filing Date: 2002-11-19
Classification: B23Q,G05B,Y10T

Abstract:
An apparatus for detecting a contact of a tool to a workpiece, comprising:means for electrically coupling a first lead to one of the workpiece and a holder and a table, the holder supporting the workpiece, the table supporting the workpiece and the holder; means for electrically coupling a second lead to a machine at a point electrically insulated from the first lead, the machine operating the tool; means for generating a signal whenever a circuit between the first lead and the second lead is closed; a first oscillator adapted to receive the signal; a piezoelectric acoustic transducer receiving an activation signal from the first oscillator, and a second oscillator adapted to receive the signal and supply an output to the first oscillator; and wherein the output of the second oscillator periodically prevents resonance of the piezoelectric acoustic transducer.