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. 22, 1991
Filed:
Nov. 14, 1988
John Bizjak, San Jose, CA (US);
Michael Hassel, Milpitas, CA (US);
David Niemann, Santa Clara, CA (US);
Brier Technology, Inc., San Jose, CA (US);
Abstract
The present invention utilizes a dual frequency data writing scheme. At a first frequency, flux transitions are achieved which result in large excursions of the information signal. In the preferred embodiment, the first frequency approximates the maximum frequency at which such excursions can occur. A second higher frequency is utilized to create the very small or no excursions. At this second higher frequency, a complex flux transition is not achieved. Therefore, there is little or no information signal. Information is represented by the presence or absence of excursions. In the preferred embodiment, the first frequency is approximately 33,000 flux changes per inch, and the second frequency is approximately 67,000 flux changes per inch. In order to detect data written by the present scheme, an adaptive, self-compensating scheme is utilized. The present invention utilizes an excursion detection scheme which is pattern and radii independent. This scheme is self-adjusting in real time and provides recovery of the nominal flux transition independent of the information pattern. Data recovery is qualified through use of a novel excursion detection scheme. This scheme compares variations in the tracking peak detect value with the input signal separated by an excursion threshold value. When the input waveform falls below the adaptive threshold voltage, a data transition is defined.