Patent ID: 6573725
Filing Date: 2003-06-03
Classification: G01R

Abstract:
A sensor for an electrostatic detector in the form of an electrostatic voltmeter comprising:(a) an elongated vibratory element having two ends; (b) means for supporting said vibratory element at one of said ends as a cantilever beam and defining a mechanical mounting node at said end; (c) a sensitive electrode on said vibrating element near the other of said ends and disposed toward an electrical charge, field or potential being detected having capacitive coupling to said sensitive electrode; (d) a drive transducer rigidly attached to said vibratory element at a predetermined location thereon for vibrating said element at a predetermined frequency in a direction to vary the capacitive coupling between said sensitive electrode and the electrical charge, field or potential being detected; (e) an oscillator operatively connected to said drive transducer for operating said transducer to vibrate said element; (f) the location of said drive transducer and the frequency of vibration of said element being selected to vibrate said element at a frequency above the fundamental vibration frequency of the cantilever beam so that a substantially compensating torque is produced at the mechanical mounting node of the beam so as to greatly reduce net torque applied to said mounting node so that the degree of stiffness of the mounting node does not significantly affect the operating frequency of the beam or the displacement of the free end of the beam; and (g) means for deriving an electrical signal from said sensitive electrode containing information about the electrical charge, field or potential being detected.