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:
Dec. 11, 1984
Filed:
Feb. 10, 1982
Robert McFarlane, New Rochelle, NY (US);
George C Kenney, II, Ossining, NY (US);
North American Philips Corporation, New York, NY (US);
Abstract
A closed loop control system for an optical recording apparatus of the read after write type comprises a comparator for comparing the input data signal with a playback signal derived from the read beam which trails the write beam and is modulated by the data pattern inscribed on the recording medium by the write beam. The error signal generated by the comparator is applied to a controller which varies the modulation of the read beam in dependence on the error signal, for example, by modifying the data signal used to drive the write beam modulator. In this way, the control system compensates for nonuniformities in the recording medium and the like so as to ensure that the pattern inscribed by the write beam accurately represents the data to be stored.