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:
Mar. 26, 1985
Filed:
Sep. 29, 1982
John E Callan, Milwaukee, WI (US);
Allen-Bradley Company, Milwaukee, WI (US);
Abstract
An a.c. input circuit for converting a sensed a.c. voltage into a logic level voltage includes a rectifier for converting the sensed a.c. voltage to a d.c. voltage which is supplied through a coupling impedance to the light emitter of an optical isolator. While the a.c. input voltage is below a first predetermined voltage, a switchable low impedance circuit path in parallel with the light emitter is rendered conductive to maintain a low impedance across the light emitter to prevent the light emitter from becoming conductive. A switchable high impedance circuit path in parallel with the switchable low impedance circuit path becomes conductive once the sensed a.c. input voltage reaches the predetermined voltage to drive the light emitter into hard conduction. The switchable high impedance circuit path remains conductive until the sensed a.c. input voltage drops below a second predetermined value, at which point the light emitter is turned off and the switchable low impedance path becomes conductive.