The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
May. 23, 1995
Filed:
Mar. 18, 1993
Steven K Harbaugh, Castro Valley, CA (US);
Authentication Technologies, Inc., Dublin, CA (US);
Abstract
A verification device for a security thread embedded within currency paper includes two or more sensor channels, each channel comprising a sensor plate and a guard plate disposed adjacent to one another. The sensor plate and guard plate of one channel are in a planar relationship with the sensor plate and guard plate of all other channels. A transistor has its base connected to the sensor plate and its emitter connected to the guard plate, thereby effectively removing any stray capacitance between the sensor and guard plates. The output of the transistor at its emitter is indicative of the amount of the electrical charge on the sensor plate. Signal processing electronics disposed after the transistor convert the sensor plate capacitance into an electrical signal whose pulse width is proportional to the amount of sensor plate capacitance. A valid currency having a security thread embedded therein passes by a sensor plate and varies the amount of capacitance of the plate. The signal processing electronics is responsive to this variation in sensor plate capacitance and provides a signal indicative of the valid security thread.