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:
Sep. 14, 1999
Filed:
Mar. 12, 1998
Daryl Minoru Shiraki, San Jose, CA (US);
Komag, Incorporated, San Jose, CA (US);
Abstract
A memory media tester uses a dynamic threshold margin between the sensor signal produced by a sensor and a threshold level. The dynamic threshold margin is generated as a function of a DC signal generated by converting the sensor signal to a DC voltage, where the sensor signal is composed of a noise level and signal spikes. The rate of change of the DC converted signal is controlled in order to prevent the DC converted signal from being significantly affected by the signal spikes. The dynamic threshold margin may be produced as a dynamic threshold level, a dynamically amplified output signal, or both. The sensitivity of the dynamic threshold margin may be electronically adjusted. The dynamic threshold margin automatically adjusts to changes in the DC converted signal, such as when there is a change in the surface roughness of the media, or when the sensor loses sensitivity. The sensor signal may then be compared to the threshold level, where the difference between the threshold level and the noise level is the dynamic threshold margin. A defect is found when the sensor signal exceeds the threshold signal.