Dynamic magnetic information storage or retrieval – Head – Core
Reexamination Certificate
2002-04-10
2004-10-05
Heinz, A. Jo (Department: 2652)
Dynamic magnetic information storage or retrieval
Head
Core
Reexamination Certificate
active
06801391
ABSTRACT:
CROSS REFERENCES TO RELATED APPLICATIONS
The present document is based on Japanese Priority Document JP 2001-114969, filed in the Japanese Patent Office on Apr. 13, 2001, the entire contents of which being incorporated herein by reference.
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a magnetic head used for a magnetic tape, one of a magnetic recording medium, in a video tape recorder (VTR), for example, and a method of manufacturing the magnetic head.
2. Description of the Related Art
Along with development in digitalization in recent years, higher recording density is required in a field of magnetic recording. With regard to a magnetic head using a magnetic tape as a recording medium, those excellent in recording/reproducing performance (hereinafter, simply referred to as “head performance”) in its frequency bandwidth to be used are expected. As a magnetic head suitable for realizing such a high recording density, a thin film magnetic head such as a magneto-resistive (MR) head and a bulk-type Metal-In-Gap (MIG) head have been suggested. Among these, in view of reduction in product cost, the bulk-type MIG head is widely employed.
The bulk-type MIG head is formed with, as shown in
FIGS. 9A and 9B
, a pair of magnetic core halves
21
, each comprising a magnetic material, such as ferrite, fitted to abut on each other. A portion where the magnetic core halves
21
abut on each other functions as a magnetic gap
22
. A metal magnetic film
23
comprising a ferromagnetic material, such as Sendust, is arranged only in the vicinity of the magnetic gap
22
. This arrangement improves the head performance. The magnetic core halves
21
are bonded to each other with low melting glass
24
to be a single body.
For slide contact with a magnetic tape, the MIG head has a slide contact plane
25
formed to be substantially arc. One end of the magnetic gap
22
, the metal magnetic thin film
23
arranged in the vicinity of the magnetic gap
22
and the pair of magnetic core halves
21
for sandwiching them is exposed on the slide contact plane
25
. In addition, the MIG head has a winding opening
26
positioned substantially at the center of the pair of the magnetic core halves
21
and a coil guide notch
27
provided at an edge of each of the magnetic core halves
21
. As illustrated in
FIG. 10
, a coil wire
28
is wound along a direction substantially parallel to the slide contact plane
25
utilizing the winding opening
26
and the coil guide notches
28
.
As described above, the magnetic heads including the MIG head are expected to have excellent head performance. It is considered that improvement of the head performance can be realized by, for example, optimizing the property (such as soft magnetic property), the structure (such as plural laminated films) or the film-forming conditions (such as angle of incidence, direction of easy magnetizable axis) of the metal magnetic thin film
23
for attaining higher permissivity and higher saturation density at the magnetic core in the vicinity of the magnetic gap
22
, or by adjusting a crystal direction of the magnetic core halves
21
for reducing noise signals. However, a number of factors affect each other in optimization of the metal magnetic thin film
23
and the crystal direction, a variety of studies are required in a process from development to practical application, that is, it takes quite a long time until the practical application. Accordingly, the above-mentioned ways are not always appropriate from a point of view of earlier practical application and lower production cost.
Alternately, there is another way for solving difficulties in the earlier practical application and the promotion of reduction in production cost that, for example, the number of winding of the coil wire
28
is increased so as to improve the head performance. The more the number of winding of the coil wire
28
increases, the more the recording/reproducing performance of the magnetic head is improved. However, if the number of winding of the coil wire
28
is simply increased, inductance L thereof becomes greater. This may possibly make the value of the inductance L beyond a range of its standard values (rated values).
If a volume of the magnetic core formed with the pair of magnetic core halves
21
, that is the volume of the magnetic body, is reduced, increase of the inductance L is suppressed. Thus, it is possible to avoid such a disadvantage described above. However, when the reduction in volume of the magnetic body makes the outside dimension (thickness, width or the like) of the magnetic head smaller, there arise problems that mechanical strength of the magnetism core itself drops, that specification change of a drum on which the magnetic head is mounted is required, and that an area of the slide contact plane necessary for slide contact with the magnetic tape cannot be easily ensured.
In view of the problems as described above, as disclosed in Japanese Patent Application Publication Hei 6-274816, a magnetic head which has a magnetic core with a smaller volume without changing the outer shape of the magnetic head and without deteriorating mechanical strength thereof by forming the magnetic core with a bonded body comprising a magnetic ferrite and a nonmagnetic ferrite laminated thereon. According to the disclosed magnetic head, since it is possible to reduce volume of the magnetic core, increase of the inductance L is suppressed even if the number of winding the coil wire is increased. As a result, it is possible to improve the head performance while solving the problems in mechanical strength and compatibility to the conventional products.
However, in the magnetic head using the magnetic core, since the bonded body in which the nonmagnetic ferrite is laminated on the magnetic ferrite is used, a complicated bonding step in which pressurization at a high temperature (hot press) of 1000° C. or more, for example, is carried out on the magnetic ferrite and the nonmagnetic ferrite is required in addition to usual head forming steps. This makes the productivity largely drop. This may make it unfavorable in promotion of reducing production cost. In addition, since the magnetic core has a two-layer structure comprising the magnetic ferrite and the nonmagnetic ferrite laminated thereon, there is less flexibility in shaping the magnetic core and the magnetic ferrite and the nonmagnetic ferrite cannot be always arranged at appropriate positions. Furthermore, difference in thermal expansion coefficients between the magnetic ferrite and the nonmagnetic ferrite, the bonded body may have distortion or other problems.
SUMMARY OF THE INVENTION
In the present invention, a portion that does not contribute much to improvement of the head performance on a magnetic circuit basis among structural parts of a magnetic head has been focused. According to the present invention, while problems in mechanical strength of the magnetic head and compatibility with a conventional product are solved, volume of the magnetic body is decreased. This realizes a magnetic head having excellent head performance, which does not reduce production efficiency nor introduce lack of flexibility in forming a magnetic core.
The magnetic head according to the present invention is formed to have a nonmagnetic gap positioned between a pair of magnetic core halves and to have a slide contact plane for slide contact with a magnetic recording medium, formed by exposing one end face of the nonmagnetic gap and the magnetic core halves. In the magnetic head, a nonmagnetic portion filled with a glass material is provided at an outer end of the slide contact plane than the one end face of the magnetic core halves on the slide contact plane.
The present invention also provides a manufacturing method of the magnetic head. According to the present invention, there is provided a manufacturing method of a magnetic head formed to have a nonmagnetic gap positioned between a pair of magnetic core halves and to have a slide contact plane for slide contact with a magnetic rec
Kaneyama Naoyuki
Konno Akihiro
Sugawara Akira
Heinz A. Jo
Sonnenschein Nath & Rosenthal LLP
LandOfFree
Magnetic head with ferrite between nonmagnetic portions and... does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Magnetic head with ferrite between nonmagnetic portions and..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Magnetic head with ferrite between nonmagnetic portions and... will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-3277417