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:
Oct. 17, 2000
Filed:
May. 09, 1997
Stephen Paul Langford, Bristol, GB;
Benjamin Alec Willcocks, Bristol, GB;
Hewlett-Packard Company, Palo Alto, CA (US);
Abstract
During retrieval of data from tape in a helical scan tape drive mechanism with a rotary head drum, movement of tape past the drum by a capstan is controlled to keep the tracks recorded on the tape in alignment with paths followed by the heads. A time interval is measured between occurrence of a drum position pulse generated at a specific angular position of the drum, and detection of reference signals included in the tracks (such as specific portions, with known bit patterns, of the data in the tracks). The capstan is operated to keep this interval equal to a set reference value. If a change in the reference value is required, such as at a transition between data recordings made at different times, the tape is moved at a slower than normal speed, and multiple measurements are made of the time interval as it cycles through a range of values in consequence of the changed tape speed. The mean value of these multiple measurements is used as the new reference value.