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. 25, 1995
Filed:
Oct. 12, 1994
Allen A Bahr, Tucson, AZ (US);
Tony R Larson, Tucson, AZ (US);
International Business Machines Corporation, Armonk, NY (US);
Abstract
A system for accurately measuring current drawn intermittently by an inductive load over a time interval T including a first and a second time subinterval during which the load is in state S1 and state S2 respectively and drawing current and a third time subinterval during which the load is in state S3, an idle state, and drawing substantially zero current is provided. In a preferred embodiment, the current measuring system includes a pilot current detection circuit having a pulse width modulator which generates a 1/2T.sub.1 timing signal representing the average amplitude of the current drawn by the load while in states S1 and S2. A correction circuit generates a logic signal that indicates the time of transition of the inductive load from state S2 to state S3 and from state S3 to state S1. The logic signal is used to clock a first sample and hold circuit to provide a scaling factor utilized to correct the average load current. Thereafter, the average load current and the scaling factor are combined in a multiplier to provide a scaled average load current to control the inductive load.