Spatio-temporal measurement of one-dimensional surface potential distributions using a surface voltmeter and a slit plate

Abstract

Fine parallel electrodes with an electrode pitch ranging from sub-mm to mm have been utilized in electrostatic devices. Evaluating the surface potential distributions of those electrodes are essential in characterizing the electrostatic devices. However, the spatial resolution of commercially available surface voltmeters are insufficient for the evaluations. Targeting at one-dimensional distributions, this work improves the spatial resolution of a voltmeter using a slit plate. A slit plate narrows the field-of-view and realizes a higher resolution in measurement of one-dimensional potential distributions created by parallel electrodes. Field simulations showed that a thin and narrow slit can improve the spatial resolution. Experiments using a slit with a thickness of 0.02 mm and a slit opening of 0.2 mm confirmed the improvement in measurement of a potential distribution produced by parallel electrodes with an electrode pitch of 1 mm. The method was extended for visualizing time variations of surface potential distributions, in which the slit plate was oscillated for scanning. Using the extended method, a potential distribution was scanned at 40 frames per second. The method was applied to evaluation of surface potential distributions of an electrostatic film motor that has three-phase electrodes with an electrode pitch of 0.2 mm. The result of the potential measurement coincided with the force measurement in terms of their break frequencies.