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:
Aug. 06, 1991
Filed:
Jun. 02, 1989
Fuji Photo Film Co., Ltd., Kanagawa, JP;
Abstract
When a light beam is applied to a surface of a back-coated magnetic recording medium such as a long magnetic tape, the light reflected by the recording medium surface is polarized. The angle of rotation of the plane of polarization of light reflected by the magnetic layer of the recording medium is different from the angle of rotation of the plane of polarization of light reflected by the back coating layer of the recording medium. The light reflected from the surface of the recording medium is applied to a polarizer which allows only linearly polarized light that vibrates in a predetermined direction to pass through itself. Then, the intensity level of the linearly polarized light is detected to determine whether the light was reflected from the magnetic layer or the back coating layer.