Piezoelectrically driven transducer for electron work function and contact potential measurements

Claim 1

A piezoelectric transducer apparatus for measuring contact potentials between relatively movable electrodes and electron work function of surfaces and for atomar molecular and optical chopper applications, said apparatus having a piezoelectrically driven movable electrode and a counter-electrode, means for providing an oscillatory driving voltage for said movable electrodes, spring means for mounting said movable electrode and means for providing a controllable voltage superimposed on said oscillatory driving voltage for variation of the means spacing between said movable electrode and said counter-electrode, said movable electrode having first and second poles respectively on opposite sides of a position of said movable electrode to which said oscillatory driving voltage means provides said voltage to said movable electrode, said means for providing oscillatory driving voltage including a self excited oscillation generator circuit (8, 9, 13), having a reference or ground potential conductor (19), said apparatus further comprising a capacitor (20) connected between said first pole (5) of a piezoelectric driving element (4) of said movable electrode and said oscillation generator circuit; a connection between said second pole (6) of said piezoelectric element and said reference or ground potential conductor; connection means for applying said controllable voltage in parallel to said poles (5, 6) of said piezoelectric element, and an amplitude control circuit (26, 27, 28, 29) for varying the amplitude of said oscillatory driving voltage.