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:
Jun. 27, 1989
Filed:
Oct. 15, 1987
David V Cronin, Peabody, MA (US);
John M Guerra, Concord, MA (US);
Paul F Sullivan, Westwood, MA (US);
Patricia A Mokry, Medford, MA (US);
Peter P Clark, Acton, MA (US);
Vincent L Cocco, Wakefield, MA (US);
Polaroid Corporation, Cambridge, MA (US);
Abstract
A magnetic data storage system for use with a double sided disk in which a prerecorded pattern of opaque optical lines is used to define the tracks in which magnetic data is to be stored. A separate optical system including an illumination source and a photosensitive detector is provided on a read/write assembly for each side of the disk. Each detector is designed also to serve as a reference grating. The illumination source is designed to image the prerecorded pattern of optical lines on the reference grating as an indication of the alignment of the read/write head of the assembly and a desired data rack and any misalignment of the head and track generates a servo signal. The detector uses four separate photocells interleaved in a prescribed fashion to form a quadrature detector that is adjustable to compensate for various non-uniformities. One form of illumination source uses a surface-emitting light emitting diode and optics for forming a multiple beam source.