Electricity: measuring and testing – Impedance – admittance or other quantities representative of... – Lumped type parameters
Reexamination Certificate
2006-04-04
2006-04-04
Nguyen, Vincent Q. (Department: 2858)
Electricity: measuring and testing
Impedance, admittance or other quantities representative of...
Lumped type parameters
C324S679000
Reexamination Certificate
active
07023222
ABSTRACT:
The present invention provides a capacitive sensing technique that is advantageously useful for security applications wherein digital technology is used to measure frequency shifts caused by a conductive or grounded object moving within a capacitive sensing field. The system includes a floating reference to compensate for drifting or offsets caused by electrical noise or other environmental conditions. The system also includes a CPLD integrated circuit or microprocessor and operative to monitor changes in a sensing field signal and digitally compare a reference signal to the sensing field signal such that when a difference between the two signals exceeds a predetermined threshold, an object detection signal is generated by the monitor circuit which causes the activation of an alarm signal.
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patent: 2001/0038291 (2001-11-01), Charneau et al.
Gifford, Krass, Groh Sprinkle, Anderson & Citkowski, P.C.
Invisa, Inc.
Nguyen Vincent Q.
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