Dynamic magnetic information storage or retrieval – Head – Core
Reexamination Certificate
1997-12-17
2001-04-24
Miller, Brian E. (Department: 2754)
Dynamic magnetic information storage or retrieval
Head
Core
C360S122000
Reexamination Certificate
active
06222701
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to a novel magnetic head used for a magnetic recording/reproducing apparatus, such as a video tape recorder. More particularly, it relates to a novel magnetic head improved in the playback output and abrasion resistance.
2. Description of Related Art
In a magnetic recording/reproducing apparatus, researches into increasing the recording density or the transfer rate are proceeding. Specifically, in recent magnetic recording/reproducing apparatus, the magnetic wavelength is less than 1 &mgr;m, the relative velocity between the magnetic head and the magnetic recording medium is not lower than 5 m/s and the maximum frequency during recording/reproduction is not less than 10 MHz.
Up to now, a magnetic head shown in
FIG. 1
or in
FIG. 2
is used for the above-described magnetic recording/reproducing apparatus. The magnetic head shown in
FIG. 1
has the plane orientation of a magnetic core in the so-called VHS orientation, while the magnetic head shown in
FIG. 2
is such a magnetic head having the plane orientation of a magnetic core in the so-called &bgr;-orientation.
This type of the magnetic head is made up of a first magnetic core half
13
m
and a second magnetic core half
13
n
abutted and connected to each other so that a magnetic gap g1 is defined between the abutting surfaces thereof. The first magnetic core half
13
m
is made up of a single-crystal ferrite
11
m
and a polycrystal ferrite
12
m
joined together, while the second magnetic core half
13
n
is made up of a single-crystal ferrite
11
n
and a polycrystal ferrite
12
n
joined together.
That is, in these magnetic heads, the sides of the magnetic core halves
13
m
,
13
n
towards a medium sliding surface
11
a
defining the magnetic gap g1 are formed by single crystal ferrites
12
m
,
12
n
, while the bottom side of the magnetic head is formed by the polycrystal ferrites
11
m
,
11
n
. These magnetic core halves are formed so that the position of the magnetic gap g1 formed at the junction between the magnetic core halves
13
m
,
13
n
integrated to each other is coincident with the position of the top of the single crystal ferrites
11
m
,
11
n
in the medium sliding surface (R-TOP) so that the magnetic recording medium is contacted with the magnetic gap g1.
With the magnetic head of the VHS orientation, shown in
FIG. 1
, the single ferrite cores
11
m
,
11
n
are arranged so that the medium sliding surface is on the (211) plane and the abutment surface
11
b
of the magnetic core halves
13
m
,
13
n
is on the (111) plane.
In the magnetic head having the VHS orientation, the single crystal ferrites
11
m
,
11
n
, making up the magnetic core halves
13
m
,
13
n
, are arranged so that the directions of the <100> crystal axis orientations B1, B2 within the (110) plane in the lateral side of the magnetic head will be symmetrical with respect to the magnetic gap g1. This assures superior playback characteristics especially in the high frequency range.
However, the magnetic head having the crystal axis orientation of the single crystal ferrites
13
m
,
13
n
arrayed in this manner tends to be worn out more readily than the magnetic head having the &bgr;-orientation, such that it has only a short service life as a magnetic head. Moreover, since the <100> crystal axis orientations B1, B2 within the (110) plane on the lateral side
11
c
of the magnetic head are symmetrical with respect to the magnetic gap g1, the single crystal ferrite
11
m
of the first magnetic core half
13
m
has the resistance against abrasion with respect to the magnetic recording medium different from that of the single crystal ferrite
11
n
making up the second magnetic core half
13
m
. Therefore, if the medium sliding surface
11
a
is worn out due to repeated sliding operations of the magnetic recording medium, the medium sliding surface
11
a
is not uniformly worn out, but undergoes partially proceeding abrasion.
If partially proceeding abrasion occurs, the top (R-TOP) of the single crystal ferrites
11
m
,
11
n
and the magnetic gap g1 become non-coincident with each other on the medium sliding surface
11
a
thus deteriorating the abutting contact of the magnetic head with the magnetic recording medium. If the magnetic recording medium has sliding contact with the magnetic head further, the partially advancing abrasion is increased further until ultimately the magnetic recording medium ceases to be contacted with the portion of the magnetic head around the magnetic gap g1. This seriously lowers the playback output especially in the high frequency range due to the effect of the spacing loss.
On the other hand, the magnetic head having the &bgr;-orientation as shown in
FIG. 2
is less susceptible to abrasion as compared to the magnetic head having the VHS orientation shown in FIG.
1
and hence has a longer service life as a magnetic head. Moreover, with the magnetic head having the &bgr;-orientation, the single crystal ferrites
11
m
,
11
n
constituting the magnetic core halves
13
m
,
13
n
are arranged so that the single crystal ferrites
11
m
,
11
n
making up the magnetic core halves
13
m
,
13
n
will have the same directions of the <100> crystal axis B1, B2 in the (110) plane on the lateral side
11
c
of the magnetic head, as shown in FIG.
1
. Therefore, the single crystal ferrite
11
m
of the first magnetic core half
13
m
has the same resistance against abrasion with respect to the magnetic recording medium as that of the single crystal ferrite
11
n
of the second magnetic core half
13
n
. Thus, the magnetic head having the &bgr;-orientation is not subjected to the partial proceeding abrasion as seen in the magnetic head having the VHS orientation. That is, the magnetic head having the &bgr;-orientation exhibits superior resistance against abrasion. However, the magnetic head having the &bgr;-orientation has poor playback performance and is low in particular in the playback output in the high frequency range.
As described above, the magnetic head having the VHS orientation is superior in playback output but inferior in resistance against abrasion, whilst the magnetic head having the &bgr;-orientation is superior in resistance against abrasion but cannot develop a superior playback output. Thus, with the conventional magnetic head, the abrasion characteristics and the playback output cannot be optimized simultaneously, such that only one of the abrasion characteristics and the playback output can be improved at the cost of the other.
SUMMARY OF THE INVENTION
It is therefore an object of the present invention to provide a magnetic head which can satisfy the demand for high abrasion characteristics and high playback output simultaneously.
The magnetic head according to the present invention is made up of a pair of magnetic core halves each having a single crystal ferrite at a portion thereof. The magnetic core halves are abutted and joined to each other, with a magnetic gap being formed between abutment surfaces of these magnetic core halves. The single crystal ferrite has its medium sliding surface slidingly contacted with a magnetic recording medium, as a (411) plane, and also has the abutment surface as a (122) plane. Preferably, magnetic core halves are each formed by a junction ferrite comprised of the single crystal ferrite bonded to a polycrystal ferrite.
With the magnetic head of the present invention, since the surface orientation of the single crystal ferrite is set so that its medium sliding surface contacted with the magnetic recording medium is set as the (411) plane and the abutting surface of the magnetic core halves is set as the (122) plane, it becomes possible to realize good abrasion characteristics and a high playback output simultaneously. That is, the present invention provides a magnetic head which is free from deterioration in the playback output ascribable to partial advancing abrasion and which can produce a high playback output.
REFERENCES:
patent: 3674944 (1972-07-01), Iemura et
Matsunaga Toru
Nihei Yukari
Suzuki Atsushi
Tamura Takashi
Urai Akira
Hill & Simpson
Miller Brian E.
Sony Corporation
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