Dynamic magnetic information storage or retrieval – Head mounting – For moving head during transducing
Reexamination Certificate
2000-03-23
2002-10-29
Tupper, Robert S. (Department: 2652)
Dynamic magnetic information storage or retrieval
Head mounting
For moving head during transducing
Reexamination Certificate
active
06473273
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a rotary head assembly, and more particularly to a rotary head assembly used in a helical-scanning-type magnetic recording and reproducing apparatus used with a magnetic tape.
2. Description of the Related Art
FIGS. 4A and 4B
are used to illustrate a conventional helical-scanning-type magnetic recording and recording apparatus. More specifically,
FIG. 4A
is a perspective view of a rotary drum, and
FIG. 4B
is a schematic view illustrating a recording operation performed on a magnetic tape.
FIGS. 5A and 5B
are used to illustrate a thin-film magnetic head used in a magnetic recording and reproducing apparatus such as a hard disk apparatus. More specifically,
FIG. 5A
is a perspective view of the thin-film magnetic head, and
FIG. 5B
is a plan view of the main portion of the thin-film magnetic head shown in FIG.
5
A.
FIG. 6A
illustrates a case where the thin-film magnetic head is used in a helical-scanning-type magnetic recording and reproducing apparatus.
FIG. 6B
illustrates a case where two such thin-film magnetic heads are used in the helical-scanning-type magnetic recording and reproducing apparatus. More specifically,
FIG. 6A
is a perspective view of a rotary head assembly in which the thin-film magnetic head is mounted to a base, and
FIG. 6B
is a development of the main portion of a side surface of a double-azimuthal-type rotary head assembly, in which the rotary head assembly of
FIG. 6A
is mounted to a rotary drum.
FIG. 7
is a schematic view illustrating the movements of a magnetic tape recording surface and the magnetic heads when a recording/reproducing operation is carried out on the magnetic tape using the rotary head assembly of FIG.
6
B.
FIGS. 8A and 8B
schematically illustrate a case where the magnetic tape is subjected to a recording operation and subsequently to a reproducing operation using the rotary head assembly of FIG.
6
B. More specifically,
FIG. 8A
is an enlarged view of the main portion of
FIG. 6B
, and
FIG. 8B
is a schematic view illustrating the movements of the magnetic head recording surface and the magnetic heads when the magnetic tape is subjected to a recording operation and subsequently to a reproducing operation.
In a magnetic recording and reproducing apparatus, such as a VTR or a computer-data recording and reproducing apparatus, using a magnetic tape as a magnetic recording medium, a recording and a reproducing operation is carried out by helical scanning. Common helical-scanning-type magnetic recording and reproducing apparatuses use a plurality of heads to increase the recording density and data transfer rate. They come in various types. One such type is illustrated in FIG.
4
A. In this type, a pair of magnetic heads H
1
and H
2
are disposed on opposite locations of a rotary drum D.
For example, single heads or combination heads may be provided. When single heads are provided one magnetic head H
1
and one magnetic head H
2
are provided. When combination heads are provided two magnetic heads H
1
and two magnetic heads H
2
are provided. Regardless of whether single heads or combination heads are used, when the rotary drum D is driven to subject a magnetic tape Tp to a recording operation using either one of the magnetic head H
1
and the magnetic head H
2
or either one of the pair of magnetic heads H
1
and magnetic heads H
2
, guard bandless recording is carried out. When guard bandless recording is carried out, a track is subjected to recording so that the recording is carried out in an overlapping manner with respect to a portion of a different track that has just been subjected to recording by either one of the other of the magnetic head H
1
and the magnetic head H
2
or either one of the other of the pair of magnetic heads H
1
and magnetic heads H
2
. For example, as shown in
FIG. 4B
, after a track T
1
has been subjected to recording by the magnetic head H
1
, a track T
2
is subjected to recording by a magnetic head H
2
so that the recording is carried out in an overlapping manner with respect to a portion of a top end of the track T
1
.
When a recording/reproducing operation is carried out by helical scanning by single heads or by combination heads, an azimuthal recording/reproducing operation is carried out. In the azimuthal recording/reproducing operation, paths (or tracks) of magnetic gaps of the magnetic heads are disposed obliquely from a magnetic-tape-transporting direction, and the magnetic gaps in the magnetic heads are inclined by predetermined azimuth angles from a track widthwise direction. The azimuthal recording/reproducing operation carried out with single heads or combination heads is a double azimuthal recording/reproducing operation in which azimuth angles &thgr;
1
and &thgr;
2
of the magnetic gaps G
1
and G
2
in the respective magnetic heads H
1
and H
2
are formed by lines inclined in opposite directions, as shown in FIG.
4
B. When the double azimuthal method is used, a track T
1
to be subjected to a reproducing operation by the magnetic head H
1
has an area overlapped by an adjacent track T
2
which has been subjected to recording by the magnetic head H
2
. The double azimuthal method is carried out to eliminate crosstalk with the adjacent track T
2
by making use of azimuthal loss in which the azimuth angle &thgr;
1
of the track T
1
and the azimuth angle &thgr;
2
of the track T
2
in this overlapping area have different sizes and are formed by lines extending in different directions. Similarly, when the track T
2
is subjected to a reproducing operation by the magnetic head H
2
, azimuthal loss is made use of to eliminate crosstalk with the adjacent track T
1
. The azimuth angles &thgr;
1
and &thgr;
2
may be the same size.
Conventionally, MIG (metal-in-gap) heads, layered-type, heads, and the like have been used as magnetic heads in helical-scanning-type magnetic recording and reproducing apparatuses. In recent years, in order to achieve higher recording density of a magnetic recording medium in VTR and data recording and reproducing apparatuses, track widths have been made smaller and higher frequencies have been used. To decrease track widths, magnetic gap widths must be made smaller. However, in MIG heads, the magnetic gaps are formed by a cutting operation, making it difficult to make them smaller in size. Thus, track widths cannot be made smaller. In addition, to decrease track widths, abutting surfaces used to form magnetic gaps need to be polished with high precision. However, it is difficult to increase the precision with which the polishing is carried out in very small magnetic gaps. On the other hand, to make it possible to use higher frequencies, the inductance needs to be made low. However, in MIG heads and layered heads, the inductance cannot be made low. MIG heads and layered heads have the disadvantage that the reproducing operation output cannot be made large when higher recording density is to be achieved.
Various thin-film magnetic heads have already being used in magnetic recording and reproducing apparatuses, such as hard disk apparatuses. In general, there are two types of thin-film magnetic heads: inductive heads used primarily for recording operations, and magnetoresistive (MR) heads primarily used for reproducing operations. Composite-type thin-film magnetic heads in which such inductive heads and such magnetoresistive heads are placed upon each other into a layered structure are frequently used in magnetic recording and reproducing apparatuses. As shown in
FIGS. 5A and 5B
, in a thin-film magnetic head
1
used in a magnetic recording and reproducing apparatus such as a hard disk apparatus, a head element portion
3
and bonding pads
4
are formed at a side surface of a slider
2
. The head element portion
3
comprises an MR head
3
a
and an inductive head
3
b
. The slider
2
is formed by cutting a wafer formed of a ceramic material such as aluminum oxide and titanium carbide (Al
2
O
3
.TiC). The inductive head
3
b
is placed on top of the MR
Alps Electric Co. ,Ltd.
Brinks Hofer Gilson & Lione
Tupper Robert S.
Watko Julie Anne
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