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:
Aug. 11, 1981
Filed:
Aug. 07, 1979
David G Williams, Birmingham, GB;
Paul A Harris, Walsall, GB;
Lucas Industries Limited, Birmingham, GB;
Abstract
A liquid level sensing apparatus includes a probe having a high positive temperature coefficient of resistivity. The probe is connected in a circuit including an operational amplifier and a series transistor which maintains the voltage across the probe constant for a fixed period following switching on of the apparatus and which produces a voltage signal related to the current flowing in the probe. This voltage signal is differentiated by a differentiating circuit to provide a signal indicating the rate of change of the voltage signal from which it is determined whether or not the probe is immersed in a cooling liquid. A warning lamp is actuated by a latching switch circuit when the probe is not immersed. A second example is described in which the probe current is maintained at a fixed level and the rate of change of the voltage across it is monitored.
Data source: USPTO (United States Patent and Trademark Office) public patent records. Weekly synchronization. How IDiyas builds this profile