Electricity: measuring and testing – Magnetic – Magnetic information storage element testing
Reexamination Certificate
2002-09-30
2004-02-24
Strecker, Gerard R. (Department: 2862)
Electricity: measuring and testing
Magnetic
Magnetic information storage element testing
C360S031000
Reexamination Certificate
active
06696832
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates generally to magnetic storage systems, more particularly, the present invention relates to testing transducer heads used in magnetic storage systems.
BACKGROUND OF THE INVENTION
Magnetic storage systems, such as magnetic disc storage systems, are commonly used to store digital information. There has been an ongoing effort to reduce the size of such magnetic storage systems while increasing their storage capacity. This has led to components which are smaller yet which must provide ever increasing performance.
The trend toward smaller component size and increased component performance has resulted in an increased likelihood that a component could fail. Early detection of potential failure, preferably during manufacture of the storage system, can increase the reliability of those system products which are placed into use. One type of failure is related to the transducer heads used in such magnetic storage systems. Transducer heads are used to read and write information on a magnetic storage medium. During the manufacture of a transducer head, a top pole of the head can be damaged by various chemicals and processing steps used during fabrication. This type of damage to the top pole is referred to as a “void”. Voids in the top pole can result in an increase in the number of errors written to and read back from data stored on the storage medium. Storage systems in which the top pole of a head has a void are particularly prone to errors when the temperature is below ambient temperature.
One way to detect transducer heads having top pole voids such that they can be discarded and removed from the manufacturing process is by visual inspection of the head using an electron microscope. However, visual inspection is time consuming and labor intensive and greatly slows down the manufacturing process. Another test which can be used to identify void heads is by testing the Bit Error Rate (BER) of the storage system at a temperature below ambient temperature. (Bit error rate is a ratio between a total number of errors read back and the total number of bits stored on a medium.) However, such a temperature test requires the storage device to be cooled and is also time consuming and labor intensive.
The present invention provides a solution to this and other problems and offers other advantages over the prior art.
SUMMARY OF THE INVENTION
The present invention relates to a method and apparatus for identifying magnetic transducers having voids in the top pole which solves the above mentioned problem.
In accordance with one embodiment of the invention, a testing method and apparatus are provided in which a first bit error rate is determined for data written at a first overshoot amount. A second bit error rate is determined for data written at a second overshoot amount. A void in a top pole of a transducer head is identified by a comparison of the first bit error rate and the second bit error rate.
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Chew Victor W K
Hew Edward Y K
Leong Wong Hon
Loh David K L
Ngwe Myint
Seagate Technology LLC
Strecker Gerard R.
Westman Champlin & Kelly P.A.
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