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:
Jul. 04, 1995
Filed:
Jul. 20, 1992
Mark T Paulsen, Chanhassen, MN (US);
Pasteur Sanofi Diagnostics, , FR;
Abstract
The present invention provides a method of detecting a fluid surface and a circuit for an ultrasonic transducer for detecting such a fluid surface. In accordance with the method, an ultrasonic transducer driver generates a first voltage proportional to the resonant frequency of the ultrasonic transducer. A reference voltage is generated and the reference voltage and the first voltage are monitored and compared, and a surface detect signal is generated when the first voltage drops below the reference voltage. The circuit of the invention includes means for generating a first voltage proportional to the resonant frequency of the transducer, means for generating a reference voltage, and a comparator for monitoring the first and reference voltages and generating a surface detect signal when the first voltage drops below the reference voltage.