Optics: measuring and testing – By monitoring of webs or thread – For flaws or imperfections
Patent
1998-06-23
2000-05-02
Font, Frank G.
Optics: measuring and testing
By monitoring of webs or thread
For flaws or imperfections
356431, 3562372, 3562373, G01N 2132, G01N 2186
Patent
active
060579269
ABSTRACT:
A magnetic disk testing method is provided, which comprises a surface defect test step of detecting, as defect data, the size of surface defect of a magnetic disk, the continuity thereof, the number thereof and the position thereof by testing magnetic disks optically and a classification step of classifying the magnetic disks to first magnetic disks, second magnetic disk and third magnetic disks on the basis of the defect data obtained in the surface defect test step. The first magnetic disks have surface defects which do not provide any problem on electric characteristics and are to be qualified through a subsequent certification test, the second magnetic disks require a further certification test for determining whether or not the surface defects thereof provide a problem on electric characteristics and the third magnetic disks have electric characteristics which are to be clearly disqualified without necessity of a further certification test, wherein the first magnetic disks are decided as qualified and the second magnetic disks are objects for the certifying test.
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Font Frank G.
Hitachi Electronics Engineering Co. Ltd.
Smith Zandra V.
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