Method and apparatus for increasing throughput on disk drive quality control testing
US4929894A · kind A · utility
Assignee
Inventor
Key dates
| Filing date | Aug 23, 1988 |
| Grant date | May 29, 1990 |
| Priority date | — |
| Expiry date | Aug 23, 2008 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG11B27/36
- WIPO fieldMeasurement
- WIPO sectorInstruments
Abstract
A method and apparatus for increasing the throughput of memory disk drive quality control testing. The apparatus consists of a delay line for delaying the input signal from the read circuitry by one period of said input signal. A difference amplifier subtracts the delayed input signal from the undelayed input signal and couples the difference to one input of a comparator. The comparator compares the difference signal to a threshold used to indicate the presence of an "additional pulse". This test is performed simultaneously with a "missing pulse" test. The method involves delaying the input signal by one period and subtracting the delayed signal from the undelayed signal. A comparison of the difference to a predetermined threshold is then performed and where the threshold is exceeded, the corresponding location on the track under test is recorded as a probable defect. This method is performed simultaneously with a conventional method of performing a "missing pulse" test.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.