Dynamic magnetic information storage or retrieval – General recording or reproducing – Thermomagnetic recording or transducers
Reexamination Certificate
1998-09-24
2001-11-13
Faber, Alan T. (Department: 2753)
Dynamic magnetic information storage or retrieval
General recording or reproducing
Thermomagnetic recording or transducers
C360S055000, C360S114050, C369S013010
Reexamination Certificate
active
06317280
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to a thermomagnetic recording medium, a thermomagnetic recording and reproducing head for recording and reproducing information using the thermomagnetic recording medium, and a device incorporating the thermomagnetic recording and reproducing head.
BACKGROUND OF THE INVENTION
Magnetic disks such as hard disks, and magnetic disk devices are widely used as external memories for computers.
Referring to
FIGS. 15 and 16
, the following description will explain a conventional magnetic recording and reproducing device for recording and reproducing information using the magnetic disk.
As illustrated in
FIG. 15
, the conventional magnetic recording and reproducing device records and reproduces information on a recording layer
122
b
(
FIG. 16
) of a magnetic disk
122
.
The magnetic recording and reproducing device feeds an input signal from a host system
171
to an encoder
175
through an interface
172
, a system controller
173
, and an ECC (error correcting codes) circuit
174
. After encoding the input signal into a serial magnetic-field-modulated signal by the encoder
175
and amplifying the signal by a pre-amplifier
176
, the resultant signal is recorded as a magnetic pattern on the recording layer
122
b
of the magnetic disk
122
by a recording-use magnetic head
102
(
FIG. 16
) of a magnetic recording and reproducing head
150
.
Meanwhile, a magnetic flux leaking from the recording layer
122
b
of the magnetic disk
122
according to a magnetization state is detected by a reproduction-use head
103
(FIG.
16
), amplified by a pre-amplifier
180
, adjusted in its waveform by a waveform equalizer
179
, goes through a PLL (phase locked loop) circuit
178
, and is decoded by a decoder
177
. The decoded signal is output to the host system
171
through the ECC circuit
174
, system controller
173
, and interface
172
, thereby reproducing information.
The serial signal amplified by the pre-amplifier
180
is also input to a servo circuit
181
. By performing a feedback-control in response to the serial signal by a driver
182
, tracking of the magnetic recording and reproducing head
150
with respect to the magnetic disk
122
is controlled. Moreover, the serial signal is also input to a servo circuit
183
, to feedback-control the rotation speed of a spindle motor
184
.
FIG. 16
shows the magnetic recording and reproducing head
150
used in the conventional magnetic recording and reproducing device. In the magnetic recording and reproducing head
150
, the recording-use magnetic head
102
made of an inductive thin-film head and the reproduction-use head
103
made of a MR (magneto-resistive) head are mounted on the back surface of a floating slider
101
. The floating slider
101
is supported by a suspension arm
120
, and moves in a floated state over the surface of the magnetic disk
122
with a rotation of the magnetic disk
122
in a direction shown by arrow X
6
. Provided on the back surface of the floating slider
101
are head terminal electrodes
105
of the recording-use magnetic head
102
, and head terminal electrodes
106
of the reproduction-use magnetic head
103
. Lead wires
121
connected to the head terminal electrodes
105
and
106
are arranged along the suspension arm
120
and connected to electric circuits corresponding to the respective heads of the magnetic recording and reproducing device.
In general, for the recording layer of the magnetic disk, a material that is a hard magnetic material and also a ferromagnetic material, for example, CoPtCr, is used.
The magnetic disk
122
is fabricated, for example, by forming a 0.5-&mgr;m-thick recording layer
122
b
made from a ferromagnetic material such as CoPtCr on a 1.5-mm-thick disk substrate
122
a.
When recording information, a current corresponding to the information to be recorded flows in the recording-use magnetic head
102
through the head terminal electrodes
105
of the recording-use magnetic head
102
. At this time, recording is carried out by sequentially inverting the magnetization of the recording layer
122
b
of the magnetic disk
122
by a signal magnetic field formed by a leakage magnetic flux from the head gap of the recording-use magnetic head
102
. The arrows in
FIG. 16
represent the magnetization state.
When reproducing information, the magnetic flux leaking from the recording layer
122
b
according to the magnetization state of the recording layer
122
b
of the magnetic disk
122
is detected by the reproduction-use head
103
. Then, a signal is output from the head terminal electrodes
106
of the reproduction-use magnetic head
103
, thereby reproducing the information.
The track width Lt of the magnetic disk
122
on which information is recorded in the above-mentioned manner is determined by the width of the recording-use magnetic head
102
. Therefore, if the width of the reproduction-use magnetic head
103
is made narrower than the track width Lt, the reproduction output is lowered. On the other hand, if the width of the reproduction-use magnetic head
103
is made wider than the track width Lt, information from an adjacent track is mixed (i.e., crosstalk occurs). Thus, the recording-use magnetic head
102
and reproduction-use magnetic head
103
are usually fabricated to have substantially the same width.
Meanwhile, an increase in quantity of information to be processed has created a demand for high recording density. In order to achieve high-density recording, it is necessary to improve not only the linear density of recording bits, but also the track density (i.e., reduce the track width Lt). Hence, efforts to reduce the track width of the magnetic heads have been made.
In order to realize high-density recording by using a magnetic recording and reproducing head of the above-mentioned conventional structure to improve the track density, it is essential to reduce the widths of the recording-use magnetic head and reproduction-use magnetic head.
However, a reduction in the track width by a decrease in the width of the reproduction-use MR (magneto-resistive) head increases the hysteresis of the magnetic properties of the head, causes readout errors, and shortens the life of the head. A reduction in the track width by a decrease in the width of the recording-use head causes a lowering of leakage signal magnetic field from the gap, resulting in insufficient recording. Furthermore, since the track width is decreased, it is necessary to fabricate the heads with high precision.
SUMMARY OF THE INVENTION
It is an object of the present invention to provide a thermomagnetic recording and reproducing head, thermomagnetic recording and reproducing device, and thermomagnetic recording medium, capable of increasing the track density by realizing a narrow track without decreasing the widths of a recording-use magnetic head and a reproduction-use magnetic head.
In order to achieve the above object, a thermomagnetic recording and reproducing head of the present invention includes:
a recording-use magnetic head for applying a signal magnetic field according to information to be recorded to a recording portion of a recording layer of a thermomagnetic recording medium heated to a recording temperature during recording;
a reproduction-use magnetic head for detecting a magnetic flux generated according to recorded information from the recording portion of the recording layer of the thermomagnetic recording medium heated to a reproduction temperature during reproduction; and
a heating head with a width narrower than the recording-use magnetic head and reproduction-use magnetic head, for heating the recording portion of the thermomagnetic recording medium to the recording temperature during recording, and to the reproduction temperature during reproduction.
With this structure, when recording information, the recording portion of the thermomagnetic recording medium, whose width is narrower than the recording-use magnetic head, is heated to the recording temperature by the heating head, and a signal magnetic field is appli
Nakajima Junsaku
Yamaguchi Takeshi
Conlin David G.
Daley, Jr. William J.
Dike, Bronstein, Roberts & Cushman, Intellectual Property Practi
Faber Alan T.
Sharp Kabushiki Kaisha
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