Dynamic magnetic information storage or retrieval – General recording or reproducing – Specifics of the amplifier
Reexamination Certificate
1997-12-17
2001-01-30
Young, W. (Department: 2753)
Dynamic magnetic information storage or retrieval
General recording or reproducing
Specifics of the amplifier
C360S046000
Reexamination Certificate
active
06181501
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention generally relates to an information recording and reproducing apparatus and, more particularly, to a reproducing circuit for a magnetic recording and reproducing apparatus which amplifies a reproduction signal generated by a reproducing head and supplies the amplified reproduction signal to a signal processing circuit.
In recent years, a high frequency is used for signals reproduced by a magnetic disc apparatus in order to increase density and transfer speed of data. Thus, it is desirous to improve a high-frequency characteristic of a reproducing circuit which amplifies a signal generated by a magnetic head.
On the other hand, in the magnetic disc apparatus, the reproduction signal output from the magnetic head is supplied to a head IC through a transmission line such as a CAPS, a lead wire or a flexible pattern circuit (FPC), and the signal is amplified by the head IC. Such a transmission line has a capacitance and, thereby, the high-frequency characteristic of the reproduction signal is deteriorated and a cutoff frequency is decreased. Additionally, the high frequency characteristic of the reproduction signal is also deteriorated due to a frequency characteristic of the head IC.
Accordingly, it is desirous to improve the high frequency characteristic of the transmission line and the head IC so as to achieve an accurate transfer of the reproduction signal from the reproducing head to the head IC.
2. Description of the Related Art
FIG. 1
is a block diagram of a conventional magnetic disc apparatus. The conventional magnetic disc apparatus
100
shown in
FIG. 1
records information on a magnetic disc
101
provided therein. The magnetic disc
101
is rotated by a spindle motor
102
in a direction indicated by arrow A. A magnetic head
103
is positioned above the magnetic disc
101
so as to record information on the magnetic disc
101
and read the information from the magnetic disc
101
. The magnetic head
103
is supported on an end of an arm
104
. The magnetic head
103
performs a recording operation or a reproducing operation while the magnetic head
103
is floated above the magnetic disc
101
due to a rotation of the magnetic disc
101
.
The arm
104
is rotatably supported by a rotational shaft
105
. An end of the arm
104
opposite to the end on which the magnetic head
103
is mounted is formed as a part of a voice coil motor
106
. Thereby, the arm
104
can be rotated in directions indicated by arrows B about the rotational shaft
105
so that the magnetic head
103
is moved substantially in a radial direction of the magnetic disc
101
.
The magnetic head
103
is connected to a head integrated circuit (head IC)
108
via a connection line
107
. The connection line
107
comprises a lead wire and a flexible printed circuit (FPC). The head IC
108
is formed on the flexible printed circuit which can flexibly follow rotation of the arm
104
in the directions indicated by the arrows B. The head IC
108
amplifies a write current supplied to the magnetic head
103
so as to record information on the magnetic disc
101
. The head IC
108
also amplifies a read current which is generated by the magnetic head
103
due to changes in a magnetic flux density provided by the magnetic disc
101
.
FIG. 2A
is a plan view of an arm structure including the arm
104
;
FIG. 2B
is a side view of the arm structure shown in FIG.
2
A. The arm structure comprises a plurality of arms
104
so as to support a plurality of magnetic heads
103
. Hereinafter, a description will be given of one of the arms
104
. The connection line comprises a lead wire
107
a
and an FPC
107
b
. The magnetic head
103
is connected to an end of the FPC
107
b
via the lead wire
107
a
. The FPC
107
b
is provided with wire patterns, and the head IC
108
is connected to the wire patterns. Thus, the magnetic head
103
is connected to the head IC
108
via the lead wire
107
a
and the wire patterns of the FPC
107
b.
FIG. 3A
is a plan view of the FPC
107
b
;
FIG. 3B
is a plan view of an end of the FPC
107
which is located on the side of the magnetic head
103
;
FIG. 3C
is a plan view of an end of the FPC
107
b
which is connected to a circuit board.
The FPC
107
b
comprises a flexible board
201
on which a printed wire pattern
200
is formed. The flexible board
201
has a connection end
203
and a connection end
207
which are opposite ends of the flexible board
201
. The printed wire pattern
200
is formed on the flexible board
201
between the connection ends
203
and
207
. The printed wire pattern
200
comprises a wire pattern
202
on the side of the connection end
203
and a wire pattern
206
on the side of the connection end
207
. A head IC mounting portion
205
is formed between the wire pattern
202
and the wire pattern
206
.
An end of the lead wire
107
a
is connected by solder to a terminal
204
formed on the connection end
203
of the FPC
107
b
. The opposite end of the lead wire
107
a
is connected to the magnetic head
103
. The head IC
108
is soldered to the head IC mounting portion
205
. Accordingly, a reproduction signal transmitted to the wire pattern
202
is supplied to the head IC
108
. The head IC
108
amplifies the reproduction signal and outputs the amplified signal to the wire pattern
206
. Accordingly, the amplified signal is transmitted to the connection end
207
.
The connection end
207
of the FPC
107
b
is connected to a circuit board (not shown in the figure). A pull-up circuit
109
and a read channel circuit (RDC)
110
are formed on the circuit board. The pull-up circuit
109
pulls up the output of the head IC
108
and supplies the output to the RDC
110
.
FIG. 4
is a circuit diagram of the pull-up circuit
109
. The pull-up circuit
109
comprises pull-up resistors R
1
and R
2
and AC coupling capacitors C
1
and C
2
. An end of each of the pull-up resistors R
1
and R
2
is connected to a power source line Vcc, and the other end of each of the pull-up resistors R
1
and R
2
is connected to the head IC
108
so as to pull up an output signal. An end of the AC coupling capacitor C
1
is connected to the end of the pull-up resistor R
1
which is connected to the head IC
108
. The other end of the AC coupling capacitor C
1
is connected to the RDC
110
. An end of the AC coupling capacitor C
2
is connected to the end of the pull-up resistor R
2
which is connected to the head IC
108
. The other end of the AC coupling capacitor C
2
is connected to the RDC
110
. Each of the AC coupling capacitors C
1
and C
2
eliminates a DC component of the output of the head IC which is pulled up by the respective pull-up resistors R
1
and R
2
, and supplies the output to the RDC
110
.
The RDC
110
demodulates the signal supplied from the head IC
108
via the pull-up circuit
109
. The signal demodulated by the RDC
110
is supplied to a microprocessor unit (MPU)
111
(refer to FIG.
1
). The MPU
111
is connected to the RDC
110
, a digital signal processor (DSP)
112
and a hard disc drive connector (HDC)
113
. The MPU
111
processes information recorded on or reproduced from the magnetic disc
101
. The MPU
111
also controls a rotation of the magnetic disc
101
and positioning of the magnetic head
103
in accordance with the information read from the magnetic disc
101
by the magnetic head
103
.
The DSP
112
generates digital data for controlling rotation of the spindle motor
102
in accordance with digital data supplied by the MPU
111
which determines rotational speed of the magnetic disc
101
. Additionally, the DSP
112
generates digital data for controlling operation of the voice coil motor
106
in accordance with digital data supplied by the MPU
111
which determines a position of the magnetic head
103
. The digital data for controlling the rotational speed of the spindle motor
102
and the digital data for controlling the operation of the voice coil motor
106
are supplied to a digital analog converter (DAC)
114
. The
Fujitsu Limited
Greer Burns & Crain Ltd.
Neal Regina Y.
Young W.
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