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. 06, 1976
Filed:
Sep. 23, 1974
Lloyd Michael Germain, Woodland Hills, CA (US);
Ampex Corporation, Redwood City, CA (US);
Abstract
A circuit for sensing beginning of tape (BOT) and end of tape (EOT) tape position markers on digital magnetic tape includes an illumination source disposed to emit controlled illumination onto a marker sense position along the length of a tape path, a pair of photosensors disposed to sense illumination from the illumination source which is reflected from different positions across the width of a tape lying in the tape path, a control circuit coupled to control the illumination intensity emitted by the illumination source to maintain a predetermined illumination intensity at the photosensor receiving the least intense illumination, and a comparator connected to sense and indicate substantial differences in light intensities received by the two photosensors. The utilization of a feedback signal dependent on actually sensed illumination intensity permits the controlled illumination source to drive the photosensors with a predetermined reflected illumination intensity irrespective of the reflective characteristics of the magnetic tape over wide temperature variations. Adjustment of the gain for at least one photosensor amplifier readily permits compensation at the time of manufacture for deviations from symmetry in positioning the illumination source and photosensors as well as compensation for tolerance variations in circuit components.