Electric charge detector
OwnerEdward G. Osborneinventor
Life of this patent
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Abstract
Electrostatic discharge can damage electronic equipment. It has been known to start a fire when it occurs when a motor vehicle's gasoline tank is being filled. A device for detecting, alarming, and/or neutralizing an electrostatic charge can help avoid these problems. A variable capacitor, the capacitance of which is made to vary periodically, is used to detect electrostatic charge. A first electrode of the capacitor is the object for which electrostatic charge is important. The capacitor's electrode is one by which the capacitance is varied. An amplitude of a signal from the electrode can be shown to be proportional to the electrostatic charge on the object.
Claims20
A method for detecting an accumulation of an electrostatic charge on an object with an electric charge detector comprising a capacitor, the method comprising the steps of:
- (a) causing a periodic variation of capacitance in a capacitor's electrode;
- (b) sensing a periodic signal from said electrode;
- (c) determining an amplitude of said periodic signal, said amplitude being proportional to the electrostatic charge accumulated on said object;
- (d) determining a phase of said periodic signal with respect to a phase of the periodic variation of capacitance;
- and
- (e) detecting the polarity of the electrostatic charge based on the phase of the periodic signal with respect to the phase of the periodic variation of capacitance.
An apparatus for detecting an accumulation of an electrostatic charge, said apparatus being mounted on an object for which the electrostatic charge is to be detected, the apparatus comprising:
- (a) an electrode in which a capacitance is varied periodically;
- (b) a sensor for sensing a periodic signal from said electrode;
- (c) means for determining an amplitude of said periodic signal, said amplitude being proportional to the electrostatic charge accumulated on said object;
- (d) means for determining a phase of said periodic signal with respect to a phase of the periodic variation of capacitance;
- and
- (e) means for detecting the polarity of the electrostatic charge based on the phase of the periodic signal with respect to the phase of the periodic variation of capacitance.
Dependencies are inferred from the claim text.