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:
Apr. 20, 1999
Filed:
Jan. 16, 1996
Jeffrey D Wilson, Newcastle, CA (US);
Carl R Haynie, Pilot Hill, CA (US);
William L McGeary, Huntington Beach, CA (US);
Flowline Inc., Los Alamitos, CA (US);
Abstract
A liquid level sensing apparatus, and related method, that utilizes a tuning fork assembly to detect the presence of not only a liquid or air at a particular location within a container, but also a solid material at that location. The tuning fork assembly includes an excitation transducer and a receiving transducer mechanically coupled to a pair of paddles that are exposed within the container, and a phase-locked loop control system applies an excitation signal to the excitation transducer having a frequency that is regulated to track the tuning fork's resonant frequency. A comparator compares that resonant frequency with a prescribed threshold, to determine whether the tuning fork assembly is disposed in air or a liquid. A failure of the phase-locked loop control system to lock the frequency of the excitation signal at any particular frequency indicates that the tuning fork assembly is over-damped and likely contacted by a solid material. Since the apparatus normally excites the tuning fork assembly at its resonant frequency, this allows the apparatus to be operated at reduced power levels, leading to improved efficiency.