Dynamic magnetic information storage or retrieval – Head mounting – For moving head during transducing
Reexamination Certificate
2000-03-24
2004-02-24
Watko, Julie Anne (Department: 2652)
Dynamic magnetic information storage or retrieval
Head mounting
For moving head during transducing
C360S119050, C360S241100
Reexamination Certificate
active
06697231
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a rotary head assembly for magnetic recording/playback and a method for manufacturing the same and, in particular, to a thin film magnetic head for use in a helical scan type magnetic recording/playback apparatus using a magnetic tape, a method for manufacturing the same, and a rotary head assembly using a thin film magnetic head.
2. Description of the Related Art
FIGS. 5A and 5B
illustrate a conventional helical scan type magnetic recording/playback apparatus.
FIG. 5A
is a perspective view of a rotary drum, and
FIG. 5B
is a schematic diagram illustrating recording on a magnetic tape.
FIGS. 6A and 6B
are perspective views of magnetic heads for use in a conventional helical scan type magnetic recording/playback apparatus.
FIG. 6A
is a perspective view of a MIG head, and
FIG. 6B
is a perspective view of a laminate type head.
FIGS. 7A and 7B
are perspective views of conventional magnetic heads mounted to bases.
FIG. 7A
shows a single head consisting of a single MIG head, and FIG.
7
B shows a combination head consisting of two MIG heads.
FIGS. 8A and 8B
illustrate a thin film magnetic head for use in a magnetic recording/playback apparatus such as a hard disk apparatus.
FIG. 8A
is a perspective view of a thin film magnetic head, and
FIG. 8B
is a main part plan view of FIG.
8
A.
FIGS. 9A
,
9
B and
9
C illustrate a rotary head assembly when the thin film magnetic head of
FIGS. 8A and 8B
is applied to a helical scan type magnetic recording/playback apparatus.
FIG. 9A
is a perspective view of a thin film magnetic head mounted to a base,
FIG. 9B
is a side view of a thin film magnetic head mounted to a rotary drum, and
FIG. 9C
is a schematic diagram illustrating recording on a magnetic tape by a thin film magnetic head.
FIGS. 10A and 10B
are side views of the rotary head assembly mounted to a rotary drum.
FIG. 10A
is a side view when the mounting is effected with the base inclined, and
FIG. 10B
is a side view when the surface for mounting the thin film magnetic head to the base is inclined.
In a magnetic recording/playback apparatus in which a magnetic tape is used as the magnetic recording medium, such as VCR or a data recording/playback apparatus for a computer, a helical scan type recording/playback is performed. In the helical scan type recording/playback, a so-called azimuth recording/playback is conducted, in which the track of the magnetic gap of the magnetic head is inclined with respect to the magnetic tape running direction, and in which the magnetic gap of the magnetic head is inclined by a predetermined angle (azimuth angle) with respect to the width direction of the track.
Generally speaking, in a helical scan type magnetic recording/playback apparatus, a plurality of heads are used in order to achieve an improvement in recording density and data transfer rate. For example, as shown in
FIG. 5A
, two magnetic heads H
1
and H
2
are arranged at opposed positions in a rotary drum D. The magnetic heads H
1
and H
2
may consist of a single head in which play back is performed by a single playback head on a track on which recording has been effected with a single recording head, or a combination head in which two recording heads and two playback heads are used. In either case, a so-called guard bandless type recording is performed, in which when the rotary drum D is driven and one of the magnetic heads H
1
and H
2
performs recording on the magnetic tape Tp, the track on which recording is performed overlaps a part of the region of another track on which recording has been performed immediately before that by the other magnetic head. For example, as shown in
FIG. 5B
, after recording is performed on the track T
1
, recording is performed on the track T
2
, overlapping a part of the region at the upper end of the track T
1
.
In both the single head and the combination head, a double azimuth system is adopted, in which the azimuth angles &thgr;
1
and &thgr;
2
of the magnetic gaps G
1
and G
2
of the magnetic heads H
1
and H
2
are inclined in directions opposite to each other. This is for the purpose of removing crosstalk with the adjacent track T
2
by utilizing the azimuth loss based on the difference between the azimuth angle &thgr;
1
of the track T
1
and the azimuth angle &thgr;
2
of the track T
2
. Although in the track T
1
on which playback is performed by the magnetic head H
1
, there is a region where it overlaps another adjacent track T
2
on which recording has been performed by the magnetic head H
2
. Further, at the time of playback on the track T
2
by the magnetic head H
2
also, the crosstalk with the adjacent track T
1
is similarly removed due to the azimuth loss.
As a magnetic head used in a helical scan type magnetic recording/playback apparatus, there has been conventionally used a MIG (metal-in-gap) head as shown in
FIG. 6A
or a laminate type head as shown in FIG.
6
B. In the MIG head shown in
FIG. 6A
, two half bodies Hm
1
and Hm
2
, each of which is composed of a core
51
formed of magnetic material such as ferrite, a thin film
52
provided on the abutting surface of the core
51
and consisting of a metal magnetic material, and a coil
53
wound around the body of the core
51
, abut each other. A magnetic gap Gm is formed on the surface on the thin film
52
is provided through the intermediation of a non-magnetic material such as glass. The laminate type head shown in
FIG. 6B
comprises two half bodies Hp
1
and Hp
2
, each of which is composed of two substrates
54
formed of a non-magnetic material such as crystallized glass, a laminate film
55
provided between the two substrates
54
and consisting of a plurality of layers of a magnetic material and a non-magnetic material, and a coil
53
wound around the body portion of each of them, abut each other. A magnetic gap Gp is formed at the abutting surfaces through the intermediation of a non-magnetic material such as glass.
In the MIG head shown in
FIG. 6A
, the abutting surfaces of the half bodies Hm
1
and Hm
2
are machined, and the width of the magnetic gap Gm is made a desired minute width, making it the recording/playback track width. The half bodies Hm
1
and Hm
2
are caused to abut each other after machining the abutting surfaces inclined in the track width direction, and an azimuth angle &thgr;m is provided in the magnetic gap Gm. Further, in the laminate type head shown in
FIG. 6B
, the track width is determined by the thickness of the laminate film
55
, so that there is no need to perform the machining process for determining the track width as in the MIG head Hm. The half bodies Hp
1
and Hp
2
are caused to abut each other after grinding the abutting surfaces inclined with respect to the track width direction, and an azimuth angle &thgr;p is provided in the magnetic gap Gp. In both the MIG head and the laminate type head, in the case of the double azimuth system, two magnetic heads of different and opposite azimuth angles &thgr;m and &thgr;p are prepared.
As shown in
FIGS. 7A and 7B
, one or two magnetic heads H
1
, H
2
, consisting of MIG heads, laminate type heads, etc., are mounted to the end portion of a base
56
on which a circuit board (not shown) is provided, and the end portion of the coil
53
and the circuit board (not shown) are connected.
FIG. 7A
shows a single head consisting of a single MIG head, and
FIG. 7B
shows a combination head consisting of two MIG heads arranged side by side. The magnetic heads H
1
and H
2
are mounted to the base
56
to form a rotary head assembly, and the coil
53
is connected through the circuit board (not shown) to an external processing circuit (not shown) for controlling the transmission and reception of signals. As shown in
FIG. 5A
, the rotary head assembly is mounted to opposed positions of the rotary drum D such that the magnetic gaps G
1
and G
2
are exposed on the outer peripheral surface of the rotary drum D.
Recently, in VCR and data recording/playback apparatus, to realize a hi
Alps Electric Co. ,Ltd.
Brinks Hofer Gilson & Lione
Watko Julie Anne
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