Dynamic magnetic information storage or retrieval – Head – Core
Reexamination Certificate
1993-10-14
2001-05-22
Letscher, George J. (Department: 2754)
Dynamic magnetic information storage or retrieval
Head
Core
Reexamination Certificate
active
06236538
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a magnetic structure, for example, a magnetic head to be mounted on a magnetic recording/reproducing apparatus, such as a video cassette tape recorder or an audio tape recorder, and more particularly to a multi-channel magnetic head adaptable to a high density recording/reproducing operation in which data must be simultaneously recorded/reproduced to and from an array composed of a multiplicity of head chips.
2. Description of the Related Art
A magnetic recording apparatus, such as a digital VCR for recording video signals by a PCM (Pulse Code Modulation) method or a high grade VCR for recording high grade video signals, must record a considerably large quantity of signals as compared with a conventional household VCR or a digital audio tape recorder. Therefore, wide band signals as compared with the foregoing conventional apparatuses must be recorded/reproduced. Since a multi-track recording method is effective to record/reproduce the wide band signals, a multi-channel magnetic head has been suggested. In order to reduce the size and the weight of the magnetic recording apparatus and to enlarge the recording capacity, the track must be narrowed and the relative speed between the magnetic recording medium and the head must be decreased. However, the foregoing structure raises a problem in that a reproduction signal having a sufficient S/N ratio cannot easily be obtained. Therefore, a magnetic head comprising a multiplex-winding coil and a recording/reproducing combined type head has been suggested in order to obtain a reproduction signal having a sufficient S/N ratio even if the relative speed is not sufficient high.
The multi-channel magnetic head is categorized to a magnetic head comprising a single head chip of a plural-bulk type which is secured to the base thereof and a magnetic head having an arrangement that a multiplicity of thin-film head chips are formed on the same substrate. The latter thin-film type magnetic head exhibits an advantage in terms of facility of narrowing the track and improving the relative positional accuracy between the magnetic gaps. The multi-channel thin-film magnetic head has been disclosed in Japanese Patent Laid-Open No. 4-186511, Japanese Patent Laid-Open No. 4-188414, Japanese Patent Laid-Open No. 2-179910, Japanese Patent Laid-Open No. 62-31013, Japanese Patent Laid-Open No. 61-39914 and Japanese Patent Laid-Open No. 58-94120. The multi-channel magnetic head of the recording/reproducing combined type has been disclosed in Japanese Patent Laid-Open No. 2-94014.
The conventional multi-channel thin-film magnetic head is categorized to a type arranged as shown in FIG.
68
A and comprising a magnetic head chip having a multiplicity of spiral-type coils and to a type arranged as shown in FIG.
68
B and comprising a magnetic head chip having a helical coil. Referring to
FIGS. 68A and 68B
, reference numeral
1
represents a substrate,
25
represents a spiral coil,
26
represents a helical coil, and
31
represents a magnetic core. The magnetic head chip comprising the spiral coil exhibits an advantage that it can easily be manufactured and the insulation of the coil can easily be realized. However, the fact that the area is enlarged if the number of turns is increased for the purpose of obtaining a satisfactory reproduction signal output undesirably widens the intervals between the magnetic head chips at the time of integrating a multiplicity of the magnetic head chips, and therefore, there arises a problem in that the track cannot easily be narrowed.
The magnetic head chip having the helical coil shown in
FIG. 68B
enables narrowing of the track and increasing in the number of turns to be realized easily. However, limitations present in the size of the magnetic head inhibit to obtain a sufficiently large number of turns and therefore a problem is raised in that the S/N ratio of the reproduction signal is lowered. Further, the structure arranged in such a manner that the coil
26
a
and the magnetic core
31
are integrally formed by a lithography technology inhibits satisfactorily thickening the magnetic core
31
at the time of forming the coil
26
. In this case, there arises a problem in that the recording/reproducing efficiency cannot easily be improved.
If the connection between the coil of the magnetic head chip and an external electric circuit is established by a conventional method in which the electrode pads disposed at both ends of each coil are bonded or connected by making use of connectors, the number of connections is greatly increased in a case of a multi-channel structure comprising tens to hundreds of tracks. In this case, there arises a problem that reliability deteriorates and connection cannot easily be established because the diameter of the connection cable cannot be reduced. What is worse, the size of the electrode pad sometimes limits the intervals between the magnetic head chips. Therefore, a problem rises in that the magnetic head chips cannot easily be disposed at intervals shorter than the size of the electrode pad.
The conventional multi-channel thin-film magnetic head encounters a problem in that a satisfactory tracking operation cannot be performed if the track width and the track angle have been changed due to expansion/contraction of the magnetic recording medium occurring due to heat.
SUMMARY OF THE INVENTION
The present invention is directed to overcome the foregoing problems and, accordingly, an object of the present invention is to provide a magnetic structure and a magnetic head capable of reducing the size thereof and raising the degree of integration.
According to one aspect of the present invention claimed in claim
1
, there is provided a magnetic structure comprising a substrate having a groove-shape recess having slant side-surfaces, the substrate having thereon: a first conductive passage consisting of a plurality of parallel and conductive passages formed on the two side surface and the bottom surface of the recess; a first insulating layer stacked on the first conductive passage and the substrate; a magnetic core made of magnetic material enclosed in the recess; a second insulating layer stacked on the magnetic core; and a second conductive passage formed on the second insulating layer to sequentially connect ends of the first conductive passage to form a helical coil.
According to another aspect of the present invention claimed in claim
2
, there is provided a magnetic structure comprising a substrate having a plurality of ridge-like projections each having slant side-surfaces; the substrate having thereon: a first conductive passage consisting of a plurality of parallel and conductive passages each of which is formed on opposing slant surfaces of adjacent projections and on the bottom surface between the slant surfaces; a first insulating layer stacked on the first conductive passage and the substrate; a magnetic core made of magnetic material enclosed in a groove-shape recess formed by the adjacent projections and the bottom surface; a second insulating layer stacked on the magnetic core; and a second conductive passage formed on the second insulating layer to sequentially connect ends of the first conductive passage to form a helical coil, wherein the magnetic core is separated by the projection so that a plurality of coils are integrally formed on the same substrate.
According to another aspect of the present invention claimed in claim
3
, there is provided a magnetic head comprising: a substrate on which a plurality of ridge-like projections each having slant side surfaces and having different lengths are at least disposed in such a manner that longer projections are disposed on the two sides of each of short projections; a first conductive passage consisting of a plurality of parallel and conductive passages each of which is formed on opposing slant surfaces of an adjacent short projection and a long projection and on the bottom surface between the slant surfaces; a first insulating layer stacked on
Fukumoto Hiroshi
Oda Takuji
Ohta Hitoshi
Tanaka Naoya
Yamada Naoshi
Burns Doane , Swecker, Mathis LLP
Letscher George J.
Mitsubishi Denki & Kabushiki Kaisha
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