Dynamic magnetic information storage or retrieval – Head – Magnetoresistive reproducing head
Reexamination Certificate
2002-03-07
2004-03-09
Evans, Jefferson (Department: 2652)
Dynamic magnetic information storage or retrieval
Head
Magnetoresistive reproducing head
C360S319000, C360S322000
Reexamination Certificate
active
06704178
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a multichannel magnetic head using magnetoresistive effect, mounted on a drive apparatus for driving a magnetic recording medium such as a magnetic disk or a magnetic tape, in order to read out recorded information from a plurality of tracks on these magnetic recording media.
2. Description of Related Art
As a reproducing magnetic head for reading out recorded information from a magnetic recording medium such as a magnetic tape or a magnetic disk, for example, a magnetic head using magnetoresistive effect has widely been used as a high recording density reproducing head, in particular, because the magnetic head using magnetoresistive effect can obtain high sensitivity.
When the magnetic head using magnetoresistive effect is employed as the reproducing head as described above, a recording and reproducing head is comprised of a combination of a magnetic head using magnetoresistive effect and an electromagnetic induction type magnetic head, for example.
When a multichannel magnetic head is comprised of this recording and reproducing magnetic head, it is unavoidable that the number of terminals led out from the multichannel magnetic head increases enormously.
FIG. 1
of the accompanying drawings is a schematic diagram showing a magnetic tape drive apparatus to which a multichannel magnetic head using magnetoresistive effect according to the present invention can be applied.
As shown in
FIG. 1
, in a magnetic tape drive apparatus for driving a magnetic tape
101
, the magnetic tape
101
is supplied from a magnetic tape supply reel
103
within a tape cassette
102
, guided by a plurality of guide rollers
104
and wound around a magnetic tape take-up reel
105
.
Then, during the magnetic tape
101
is being transported, a multichannel magnetic head
100
comes in slidable contact with the magnetic tape
101
to record and reproduce information on and from the magnetic tape
101
in a multichannel fashion.
FIG. 2
is a schematic plan view showing a main portion of this multichannel magnetic head
100
, and
FIG. 3
is a schematic cross-sectional view taken along the line III—III in
FIG. 2
, for example. As illustrated, in the multichannel magnetic head
100
, a first magnetic shield
131
and a first magnetic gap layer
141
are formed on a first guard substrate
121
, for example, and thereupon are parallelly disposed a plurality of magnetoresistive effect type reproducing magnetic head elements
106
facing the front end at which this magnetic head
100
, for example, comes in slidable contact with a magnetic recording medium (not shown), i.e., a sliding surface S. Leads
106
L made up of conductive layers respectively formed into required patterns are extended from sense current feeding electrodes toward the rear end edge on the opposite side of the sliding surface S.
On these reproducing magnetic head elements
106
, there is formed an insulating layer
107
, on which a second magnetic gap layer
142
having a predetermined thickness is formed. A second magnetic shield
132
is formed on the second magnetic gap layer
142
.
Then, on the second magnetic shield
132
, there are parallelly disposed electromagnetic induction type recording magnetic head elements
108
facing the sliding surface S corresponding to the respective reproducing magnetic head elements
106
.
As shown in
FIG. 3
, each of the recording magnetic head elements
108
comprises an insulating non-magnetic layer
109
formed on the second magnetic shield
132
, for example, a thin-film coil
110
formed on the insulating non-magnetic layer
109
and a belt-like magnetic core
111
formed on this thin-film coil
110
through an insulating e layer in such a manner that its front end faces the sliding surface S.
The magnetic core
111
has at the central portion of the thin-film coil
110
through-holes penetrating the non-magnetic layer
109
formed on the second magnetic shield
132
and an insulating layer formed on the non-magnetic layer
109
. The respective magnetic cores
111
are magnetically coupled to the magnetic layers made up of the second magnetic shields
132
through these through-holes, and a closed magnetic circuit is formed of the magnetic core
111
and this magnetic layer. In this manner, there is constructed the electromagnetic induction type recording magnetic head element
108
around which the thin-film coil
110
is wound and in which a magnetic gap g is formed at the front end of this closed magnetic circuit by the non-magnetic layer
109
having a required thickness.
On these recording magnetic head elements
108
, there is formed a non-magnetic insulating layer
112
on which a third magnetic shield
133
and a second guard substrate
122
are formed.
At that very time, the rear end edge of the insulating non-magnetic layer
109
, for example, is exposed to the outside.
At the rear end edge of this non-magnetic layer
109
, there are parallelly disposed sense current feeding terminals
151
and
152
for the respective reproducing magnetic head elements
106
, and terminals
161
and
162
for the thin-film coils
110
of the respective recording head elements
108
.
The terminals
161
and
162
have connected thereto end portions of leads
108
L made up of conductive layers led out from both terminals of the respective thin-film coils
110
of the respective recording head elements
108
.
On the end portions of the sense current feeding leads
106
L of the respective reproducing magnetic head elements
106
as are extended below the rear end edge of the insulating layer
112
, there are bored through-holes
150
which are communicated with these leads
106
L. Leads
106
L are each connected to the respective terminals
151
and
152
by a conductive layer formed within this through-hole
150
.
As described above, in the ordinary multichannel magnetic head, since two terminals are respectively led out from the respective magnetoresistive effect type reproducing magnetic head elements
106
and recording magnetic head elements
108
, there are led out at least four terminals
151
,
152
and
161
,
162
with respect to each channel.
As a result, it is unavoidable that the number of terminals increases enormously and that the portion in which the terminals are arrayed occupies a large area of the whole of the magnetic head. This hinders the multichannel magnetic head from being miniaturized.
Moreover, in order to miniaturize the whole of the multichannel magnetic head, the space between the terminals and the space between the leads should be decreased by decreasing the width of the terminals or by reducing the widths of the lead portions themselves from which the terminals are led out. In this case, however, a resistance at the portion from which the terminal is led out increases, poor insulation, short-circuit occur between the terminals or between the leads and so forth, which causes characteristics of the magnetic head element to be fluctuated. Moreover, it is unavoidable that reliability and a yield of the magnetic head element are lowered.
SUMMARY OF THE INVENTION
In view of the aforesaid aspect, it is an object of the present invention to provide a multichannel magnetic head using magnetoresistive effect in which the number of terminals can be decreased.
It is another object of the present invention to provide a multichannel magnetic head using magnetoresistive effect in which the whole of a multichannel magnetic head can be miniaturized.
It is still another object of the present invention to provide a multichannel magnetic head using magnetoresistive effect in which the occurrence of short-circuit and poor insulation between the terminals or between the leads can be removed.
It is a further object of the present invention to provide a multichannel magnetic head using magnetoresistive effect in which the occurrence of fluctuations of element characteristics can be removed.
It is yet a further object of the present invention to provide a multichannel magnetic head using magnetoresistive effec
Nakashio Eiji
Onoe Seiji
Sugawara Junichi
Evans Jefferson
Sonnenschein Nath & Rosenthal LLP
Sony Corporation
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