Dynamic magnetic information storage or retrieval – Head – Core
Reexamination Certificate
2000-03-09
2003-04-15
Renner, Craig A. (Department: 2652)
Dynamic magnetic information storage or retrieval
Head
Core
Reexamination Certificate
active
06549369
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a magnetic head comprising a metal magnetic thin film.
2. Description of the Related Art
In the field of magnetic recording, digital-system magnetic recording is becoming the mainstream in place of a conventional analog system. Particularly, digital system VTR is being rapidly popularized, and VTR magnetic heads are required to have higher performance.
A conventional digital-system VTR reproduction magnetic head comprises a so-called MIG-type magnetic head in which a soft magnetic alloy film is provided in a magnetic gap.
However, such a MIG-type magnetic head has a problem in that reproduction of digital signals causes various noises in reproduced signals, increasing an error rate.
Therefore, a laminated magnetic head has recently been used, which comprises a magnetic core having a structure comprising soft magnetic films held between nonmagnetic material layers. In this laminated magnetic head, the magnetic path comprises the soft magnetic films to decrease magnetostriction, thereby causing relatively low noise. The magnetic head comprising soft magnetic films laminated with insulating films provided therebetween has the advantage of suppressing an eddy current loss in the radio-frequency region and thus improving characteristics in the radio-frequency region.
Since the magnetic path comprises the soft magnetic films, the total thickness of the soft magnetic films equals the track width, and thus the track can easily be narrowed, thereby improving the recording density and preventing interference from adjacent tracks.
Furthermore, with the soft magnetic films each comprising a metal magnetic thin film made of an alloy system containing Fe and an additive element, it is possible to suppress a decrease in permeability in the radio-frequency region.
In the laminated magnetic head, the metal magnetic films comprising a plurality of metal magnetic thin films laminated with interlayer insulating layers provided therebetween are interposed between nonmagnetic substrates to form each of a pair of magnetic core halves. The magnetic core halves are bonded to each other with bonding glass provided therebetween so that the metal magnetic films of one of the pair of magnetic core halves are arranged in line with the metal magnetic films of the other and abutted thereon with a gap layer provided therebetween.
Each of the metal magnetic films has a thickness of 10 to 20 &mgr;m, while each of the substrates for holding the metal magnetic films therebetween has a thickness of several mm, and thus the thickness of each of the magnetic core halves is substantially determined by the thickness of the substrates. Namely, the substrates are mainly exposed to the abutting surfaces of the magnetic core halves. Therefore, in bonding the pair of magnetic core halves with bonding glass, the bonding glass is fused to the substrates to bond together the pair of magnetic core halves with the bonding glass provided therebetween.
The magnetic core halves are generally bonded at a temperature higher than the softening temperature of the bonding glass. However, such bonding has the problem of easily causing cracks in the bonding glass or separation of the bonding glass and the magnetic core halves during the cooling process of the substrates and the bonding glass after completion of the bonding. This problem is considered to frequently occur when a difference of the thermal expansion coefficients between the bonding glass and the substrates is great. Therefore, in order to solve this problem of the bonding glass, bonding glass having substantially the same thermal expansion coefficient as the substrates used is conventionally selected.
However, each of the magnetic core halves which constitute the laminated magnetic head has a structure in which the multilayered metal magnetic films are held between the substrates, thereby increasing the number of junction portions between components, and decreasing bonding strength, as compared with a MIG-type magnetic head. Particularly, the vicinity of a front gap near a sliding surface for a magnetic recording medium has a structure weak against external stress.
Therefore, even by using bonding glass having a thermal expansion coefficient equal to that of the substrates, the bonding strength of the front gap cannot be increased, and thus machining after the magnetic core halves are bonded together with the bonding glass has the probability of readily causing cracks in the bonding glass in the vicinity of the front gap or separation of the bonding glass from the magnetic core halves due to, for example, stress applied in machining.
SUMMARY OF THE INVENTION
The present invention has been achieved for solving the above problem, and it is an object of the present invention to provide a magnetic head permitting an increase in bonding strength near a front gap.
In order to achieve the object, the present invention provides a magnetic head comprising a pair of magnetic core halves each of which comprises at least metal magnetic thin films and which are combined so that the metal magnetic thin films of one of the magnetic core halves are abutted on the thin films of the other, wherein a winding slot is provided in the abutting portions between the pair of the magnetic core halves to form front gap and back gap on both sides of the winding slot, and the pair of the magnetic core halves are bonded together with first bonding glass adjacent to the back gap and second bonding glass adjacent to the front gap, which has a thermal expansion coefficient higher than the first bonding glass.
In this magnetic head, since the second bonding glass has a thermal expansion coefficient higher than that of the first bonding glass, the volumetric shrinkage rate of the second bonding glass in solidification from a softened state is higher than that of the first bonding glass. Therefore, the second bonding glass volumetrically shrinks by solidification while being fused to the pair of the magnetic core halves, and thus the pair of the magnetic core halves are attracted to each other by the second bonding glass to strongly bond the front gap.
In the magnetic head of the present invention, each of the pair of the magnetic core halves comprises metal magnetic films which are formed by laminating a plurality of the metal magnetic thin films with interlayer insulating layers provided therebetween, and which are held between substrates so that the metal magnetic films extend to the sides of the substrates, and the pair of magnetic core halves are abutted on each other with a gap layer provided in the front gap therebetween so that the metal magnetic films of one of the magnetic core halves are arranged in line with the metal magnetic films of the other.
In the magnetic head, since the magnetic path comprises the metal magnetic films, the total thickness of the metal magnetic films equals the track width, and the track can easily be narrowed, thereby improving the recording density, and preventing interference with adjacent tracks. It is also possible to strongly bond the front gap having a structure having many junction portions between components and weakness against external stress.
Furthermore, in the magnetic head of the present invention, the winding slot and a reinforcing groove are provided in the abutting portions between the pair of the magnetic core halves to form the front gap and back gap on both sides of the winding slot, the back gap is located between the winding slot and the reinforcing groove, and the pair of the magnetic core halves are bonded together with the first bonding glass arranged in the reinforcing groove adjacent to the back gap, and the second bonding glass arranged in the winding slot adjacent to the front gap.
In the magnetic head, the pair of the magnetic core halves are combined so that the front gap, the winding slot, the back gap, and the reinforcing groove are arranged in the abutting portions between the magnetic core halves in this order from an end serving as a sliding surface fo
Aoki Masao
Aoyagi Kinya
Masuda Kazue
Niijima Junichi
Suzuki Koji
Alps Electric Co. ,Ltd.
Renner Craig A.
LandOfFree
Multilayer film core magnetic head with bonding glasses of... does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Multilayer film core magnetic head with bonding glasses of..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Multilayer film core magnetic head with bonding glasses of... will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-3046819