Electricity: measuring and testing – Magnetic – Magnetic information storage element testing
Reexamination Certificate
2000-08-04
2002-06-18
Lefkowitz, Edward (Department: 2862)
Electricity: measuring and testing
Magnetic
Magnetic information storage element testing
C360S031000
Reexamination Certificate
active
06407544
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a method and an apparatus for testing in a manufacturing process a plurality of magnetic head devices each having a magnetic head ford recording and reading used in a hard disk, for example. More particularly, the present invention relates to a method and an apparatus for testing a plurality of magnetic head devices, which can improve testing efficiency by testing a plurality of magnetic head devices Simultaneously.
2. Description of the Related Art
FIG. 9
is a perspective view showing a magnetic head device according to the prior art. The magnetic head device H is provided with a flexure
2
at an end of a load beam (supporting member)
1
. A magnetic head
3
is supported through the flexure
2
. The load beam
1
and the flexure
2
are flexible supporting members formed with a flat spring or the like. A mount board
4
is molded at a basal end of the load beam
1
.
Recording and reading function portions
5
are provided in a trailing side end portion T of the magnetic head
3
.
The magnetic head
3
levitates with a tilt attitude caused by a leading side end portion L, which receives air flow above a disk as a recording device when the disk turns and is lifted from a surface of the disk. When the disk stops, the magnetic head
3
touches on the disk.
The recording and reading function portions
5
of the magnetic head device H includes an MR type thin film reading element, which uses a magnetic resistance effect, as its reading function portion, and an inductive type thin film recording element as its recording function portion, for example.
The magnetic head device H is tested with respect to recording and reading characteristics after its assembly is completed.
FIG. 10
is a perspective view for describing a conventional method for testing the magnetic head device H according to the prior art.
A disk-shaped recording medium
12
is held on a driver
11
and is rotationally driven. The magnetic head device H is tested with respect to recording and reading characteristics on the recording medium
12
by causing the magnetic head
3
to perform recording/reading.
The conventional method for testing a magnetic head device shown in
FIG. 10
has disadvantage that only one magnetic head can be tested at a time.
When the magnetic head device H is tested, a radial position from a center O of the recording medium
12
to a scanning region f the recording and reading function portions
5
(see
FIG. 9
) of the magnetic head
3
is set at a predetermined position for the test in order to have an equal recording/reading condition for the magnetic head device H.
For example, in
FIG. 10
, the scanning region of the recording and reading function portions
5
of the magnetic head
3
is positioned on a circumference of a radius r on the recording medium
12
.
When a plurality of magnetic head devices are placed on arbitrary and different radial positions, various conditions of each of the magnetic head devices, such as a skew angle, relative traveling speed, and others for the recording medium
12
are varied. Consequently, each of the magnetic head devices cannot be tested under equal conditions.
Also, a plurality of magnetic head devices could be located such that a scanning region of recording and reading function portions of each of the magnetic heads is positioned on a circumference of a radius r on the recording medium
12
. However, such a method cannot be adopted.
When recording/reading characteristics of the magnetic head device H is tested in
FIG. 10
, a test write signal is recorded by scanning on the circumference of the radius r on the recording medium
12
through the recording function portion of the magnetic head
3
. Then, the test write signal is read by the reading function portion of the magnetic head
3
in order to analyze a waveform of a read signal and determine whether the recording/reading characteristics of the magnetic head device H reach to a quality standard of a certain product or not.
Therefore, while one magnetic head device is scanning and recording/reading on a circumference of a radius r on the recording medium
12
while another magnetic head device is scanning and recording/reading on the circumference of the radius r on the recording medium
12
, a problem arises that each of the magnetic head devices cannot perform recording/reading with reliability. The magnetic head devices may be reading the write signals recorded of the other magnetic head devices. The magnetic head devices may over write the write signals recorded by other magnetic head devices.
SUMMARY OF THE INVENTION
The present invention is made for overcoming the above-described problem of the related art. It is an object of the present invention to provide a method and an apparatus for testing a magnetic head device, which can improve testing efficiency by testing a plurality of magnetic head devices simultaneously.
According to a first aspect of the present invention, a method for testing a plurality of magnetic head devices is provided. Each magnetic head device comprises a supporting member and a magnetic head having a recording function portion and a reading function portion at an end of the supporting member. The method the steps of placing the plurality of magnetic head devices on different scanning regions in the radial direction of a disk-shaped recording medium, each of scanning regions being slightly displaced from each other in the radial direction of the recording medium; turning the disk-shape recording medium to record a magnetic signal on the recording medium and to read the recorded magnetic signal through each of the plurality of magnetic head devices; and evaluating the plurality of magnetic head devices simultaneously through the read signal.
When the plurality of magnetic head devices are tested, each of the scanning region in the radial direction is predetermined. However, in a real test, tolerances in a certain range is allowed in the radial position.
Therefore, even when magnetic heads of the plurality of magnetic head devices are placed on the recording medium simultaneously, the scanning regions of the recording function portion and the reading function portion of each magnetic head may be held within a certain range of tolerances. Thus, various conditions such as a skew angle and relative traveling speed of the respective magnetic head devices for the recording medium can fall in the tolerance range. At the same time, all of the magnetic head devices placed on the recording medium simultaneously can be tested under virtually equal testing conditions. Therefore, the plurality of magnetic head devices can be tested simultaneously and accurately, which provides a much more efficient testing process for a plurality of magnetic head devices.
Further, while at least one magnetic head device among the plurality of magnetic head devices is performing a recording operation on the recording medium, it is preferable that other magnetic heads are adjusted to wait in order not to perform a reading operation.
When each of all the magnetic head devices placed on the recording medium simultaneously is allowed to record and read in arbitrary timing, a condition occurs where one magnetic head device is performing a recording operation while the, other magnetic head device is performing a reading operation.
In the condition where one magnetic head device is performing a recording operation while the other magnetic head device is performing a reading operation, a write signal output by the magnetic head device performing a recording operation is transmitted to the other magnetic head device performing a reading operation, which causes noise. That is, crosstalk occurs between the plurality of magnetic head devices.
According to the present invention, while at least one magnetic head device among the plurality of magnetic head devices is performing a recording operation on the recording medium, other magnetic head devices are adjusted to wait in order not to perform a reading operation. As a
Alps Electric Co. ,Ltd.
Brinks Hofer Gilson & Lione
Lefkowitz Edward
Zaveri Subhash
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