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Electrostatic Probe Using Vibrating Diaphragm

IP.com Disclosure Number: IPCOM000043005D
Original Publication Date: 1984-Jun-01
Included in the Prior Art Database: 2005-Feb-04
Document File: 2 page(s) / 48K

Publishing Venue

IBM

Related People

Sartin, DE: AUTHOR [+2]

Abstract

This article describes an electrostatic probe for use in measuring electrostatic voltages. The apparatus moves a partially shielded flat electrode mounted on a diaphragm about its rest position in a direction perpendicular to the surface of the electrode. The drive element is similar to an audio speaker wherein the diaphragm is moved by electromagnetic means in a sinusoidal manner. Fig. 1 shows an electrode 10 mounted on the surface of diaphragm 11 with a shield 12 mounted on the opposite side of the diaphragm. Electrode 10 is used to sense electrostatic voltages present on surface 13 by moving in and out toward surface 13, as shown by the arrows A and B. Drive motion is imparted by a speaker-type driver, which includes electromagnet 14, magnet driver 15 and oscillator 16.

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Electrostatic Probe Using Vibrating Diaphragm

This article describes an electrostatic probe for use in measuring electrostatic voltages. The apparatus moves a partially shielded flat electrode mounted on a diaphragm about its rest position in a direction perpendicular to the surface of the electrode. The drive element is similar to an audio speaker wherein the diaphragm is moved by electromagnetic means in a sinusoidal manner. Fig. 1 shows an electrode 10 mounted on the surface of diaphragm 11 with a shield 12 mounted on the opposite side of the diaphragm. Electrode 10 is used to sense electrostatic voltages present on surface 13 by moving in and out toward surface 13, as shown by the arrows A and B. Drive motion is imparted by a speaker-type driver, which includes electromagnet 14, magnet driver 15 and oscillator 16. The output of phase detector 17 provides a measure of the voltage on surface 13 so that adjustment of the high voltage supply 18 is accomplished to cause the supply voltage to equal the electrostatic voltage on surface 13. When the voltages are nearly equal, the output of differential amplifier 19 is zero, or nearly zero. Fig. 2 shows an alternate construction in which the electrode 10 and the shield 12 are both on the outside of diaphragm 11. Fig. 3 shows a front view of the Fig. 2 device showing the relative position of the electrode and shield on the diaphragm surface. It should be noted that since the diaphragm holds the probe and its shield, fa...