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. 26, 1994
Filed:
Feb. 04, 1993
Gregory P Hartman, Kitchener, CA;
Francois Desjardins, Ontario, CA;
Electrohome Ltd., Kitchener, CA;
Abstract
A circuit for driving a focus coil with a constant amplitude current in response to receiving a focus control signal and a horizontal scan rate signal, comprising: (a) a variable capacitance circuit connected to the focus coil to form a series combination of the focus coil and the variable capacitance circuit; (b) an amplifier circuit for receiving and amplifying the focus control signal and in response applying an amplified focus control signal to the series combination; and (c) a control circuit for receiving the horizontal scan rate signal and in response setting a predetermined capacitance of the variable capacitance circuit to obtain minimal voltage of the amplified focus control signal applied to the series combination of the focus coil and the variable capacitance circuit while maintaining constant current amplitude.