Electricity: measuring and testing – Magnetic – Magnetic information storage element testing
Reexamination Certificate
1999-06-10
2001-10-02
Strecker, Gerard R. (Department: 2862)
Electricity: measuring and testing
Magnetic
Magnetic information storage element testing
C324S202000, C324S252000, C029S603090, C360S006000, C360S313000
Reexamination Certificate
active
06297631
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a magnetic signal reproducing apparatus and, a magnetic signal reproducing method, for reproducing magnetic signals recorded in a magnetic tape by a magneto-resistance effect type magnetic head.
2. Description of the Related Art
A magneto-resistance effect element is a device whose resistance changes depending on the magnitude of an external magnetic field. A magneto-resistance effect type magnetic head comprising the magneto-resistance effect element as a magneto-sensitive element reproduces magnetic signals from a magnetic recording medium by detecting the changes of the resistance of the magneto-resistance effect element normally by supplying a fixed sense current to the magneto-resistance effect element and by detecting the fluctuation of voltage of the sense current.
Such a magneto-resistance effect type magnetic head produces a large reproducing output and is suited for high-density recording. Then, the magneto-resistance effect type magnetic head has come to be used widely in a hard disk unit having a high recording density. The magneto-resistance effect type magnetic head reproduces signals while floating minutely on the hard disk rotating at high speed in the hard disk unit.
Because the magneto-resistance effect type magnetic head produces the large reproduced output and is suited for the high-density recording, it is desired to be applied to a magnetic signal reproducing apparatus using a magnetic tape as a recording medium. However, the abrasion of a magnetic tape sliding face of the magneto-resistance effect type magnetic head poses a problem when the magneto-resistance effect type magnetic head is applied to the magnetic signal reproducing apparatus using the magnetic tape.
The hard disk unit causes almost no problem of abrasion because the magneto-resistance effect type magnetic head reproduces the signals while floating minutely on the hard disk rotating at high speed. However, when the magnetic tape is used as the recording medium, such problem occurs that the magnetic tape sliding face is abraded because the magneto-resistance effect type magnetic head reproduces the signals while contacting with and sliding along the magnetic tape.
The magneto-resistance effect type magnetic head reproduces the magnetic signals by supplying the fixed sense current to the magneto-resistance effect element and by detecting the fluctuation of the voltage as described above. However, when the part of the magneto-resistance effect element is abraded by sliding the magneto-resistance effect type magnetic head along the magnetic tape, the level of fluctuation of the voltage of the sense current corresponding to the signaling magnetic field from the magnetic tape changes. As a result, the reproduced output obtained from the magneto-resistance effect type magnetic head fluctuates considerably and the signals cannot be reproduced normally.
The magnetic tape sliding face of the magnetic head is very liable to be abraded because the magnetic tape slides along the magnetic head at high speed in the helical scan type magnetic signal reproducing apparatus in particular. Therefore, it has been very difficult to apply the magneto-resistance effect type magnetic head to the helical scan type magnetic signal reproducing apparatus.
SUMMARY OF THE INVENTION
The present invention has been proposed in view of such problems of the past described above and its object is to provide a magnetic signal reproducing apparatus, and a magnetic signal reproducing method, which can lessen the fluctuation of reproduced output in reproducing magnetic signals recorded in the magnetic tape by a magneto-resistance effect type magnetic head even if a magnetic tape sliding face of the magneto-resistance effect type magnetic head is abraded.
A magnetic signal reproducing apparatus of the invention comprises a magneto-resistance effect type magnetic head having a magneto-resistance effect element; and a sense current supplying section for supplying a sense current to the magneto-resistance effect element; and is characterized in that the value of a sense current supplied to the magneto-resistance effect element from the sense current supplying section is set to be greater than a value of sense current I
0
where asymmetry of the magneto-resistance effect element in the initial state is zeroed.
Further, a magnetic signal reproducing method of the invention for reproducing magnetic signals recorded in a magnetic tape by a magneto-resistance effect type magnetic head which reproduces the magnetic signals by supplying a sense current to a magneto-resistance effect element and by detecting a fluctuation of the voltage of the sense current is characterized in that the value of the sense current supplied to the magneto-resistance effect element is greater than a value of sense current I
0
where asymmetry in the initial state is zeroed.
According to the inventive magnetic signal reproducing apparatus and magnetic signal reproducing method described above, the current value of the sense current supplied to the magneto-resistance effect element of the magneto-resistance effect type magnetic head is set to be greater than I
0
in reproducing the magnetic signals recorded in the magnetic tape. Accordingly, as the abrasion of the magnetic tape sliding face of the magneto-resistance effect type magnetic head progresses, the difference between a voltage fluctuation level of the sense current caused when the magnetic field in the normal direction is applied to the magneto-resistance effect element and a voltage fluctuation level of the sense current caused when the magnetic field in the opposite direction is applied becomes small gradually. Then, the difference is eliminated at the stage when the magnetic tape sliding face of the magneto-resistance effect type magnetic head is abraded to a certain degree. After that, the difference is widened gradually as the abrasion of the magnetic tape sliding face of the magneto-resistance effect type magnetic head progresses further.
The asymmetry will be described later. The initial state described above refers to the state of the head when it is shipped out of a factory and when the magneto-resistance effect element is not abraded almost at all.
The specific nature of the invention, as well as other objects, uses and advantages thereof, will clearly appear from the following description and from the accompanying drawings in which like numerals refers to like parts.
REFERENCES:
patent: 5309305 (1994-05-01), Nepela et al.
patent: 5828529 (1998-10-01), Gill
patent: 4-205903 (1992-07-01), None
patent: 8-36713 (1996-02-01), None
Ikegami Tomohiro
Kamatani Yoshiteru
Ozue Tadashi
Saito Takehiko
Shirai Toshio
Maioli Jay H.
Sony Corporation
Strecker Gerard R.
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