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:
Jan. 10, 1995
Filed:
Jan. 06, 1993
Jean M Perreaut, Dijon, FR;
Bruno F Roussel, Genlis, FR;
Thomson Tubes and Displays, S.A., Paris, FR;
Abstract
A focus coil for a television is disposed between scanning electron beam generator and a planar screen and has a winding coupled between a power supply and a current sink for providing a magnetic focusing field due to current in the coil. A focusing circuit comprises a resonant circuit coupled to the focus coil for generating a parabolic current in the focus coil to account for variations in the distance between the focusing device and the screen during scanning. The resonant circuit stores a portion of the energy developed during trace intervals and returns this energy to the power supply during retrace intervals. The resonant circuit includes a capacitor and an additional coil, in series with one another, and together in parallel with the focus coil. The additional coil is magnetically coupled to the focus coil and induces a reverse current in the focus coil during the retrace interval for returning energy to the power supply.