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:
Feb. 24, 1998
Filed:
Jun. 07, 1995
David E Lewis, Black Forest, CO (US);
Discovision Associates, Ivine, CA (US);
Abstract
An apparatus for controlling a magnetic field strength of a bias coil at a focal point of a lens during recording on a medium. The apparatus includes a first controller for determining a distance between the focal point of a lens and a reference point on the recording media. A source generates a stray magnetic field having a stray field strength at the focal point. A second controller calculates a digital signal which is a function of the distance and the stray field strength. A digital-to-analog converter converts the digital signal to a driver voltage and passes the driver voltage to a current driver, which drives the bias coil. The magnetic field strength of the bias coil is thereby controlled at a predetermined value. A method is also shown for controlling the strength of a magnetic field, including the steps of determining a distance between the focal point of a lens and a reference point on the recording media, generating a stray magnetic field strength at the focal point, calculating a digital signal which is a function of the distance and stray magnetic field, converting the digital signal to a driver voltage, and applying the driver voltage to a current driver to provide a bias current to the bias coil, thereby controlling the magnetic field strength at a predetermined value.