Dynamic magnetic information storage or retrieval – General processing of a digital signal – Head amplifier circuit
Reexamination Certificate
2002-07-10
2004-03-02
Holder, Regina N. (Department: 2651)
Dynamic magnetic information storage or retrieval
General processing of a digital signal
Head amplifier circuit
C360S067000, C360S068000
Reexamination Certificate
active
06700721
ABSTRACT:
BACKGROUND OF THE INVENTION
This invention relates to magnetic recording and reproducing apparatus, and particularly to the transmission of write data and read data signals between the read/write signal processing circuit and read/write amplifier which are used when data is recorded on a recording medium.
The conventional magnetic recording and reproducing apparatus is generally comprised of, as shown in
FIG. 16
, a disk-like magnetic recording medium
1
, a magnetic head
10
, a write/read (R/W) amplifier
32
, an R/W signal processor
33
, a controller
4
, a microprocessor
5
, a servo controller
6
and an interface (I/F) circuit
7
. The R/W signal processor
33
is formed of a write data generator
38
and a read data reproducer
9
.
The record data transmitted from a host computer (hereinafter, the host) not shown is supplied to the R/W signal processor
33
through the I/F circuit
7
and controller
4
. The write data generator
38
converts this record data into a recording code which is suitable for being recorded on the magnetic recording medium
1
. This code is supplied to the R/W amplifier
32
, and fed to the magnetic head
10
by which it is written on the magnetic recording medium
1
. When the data is read from the medium
1
by the magnetic head
10
, it is amplified by the R/W amplifier
32
and then decoded by the read data reproducer
9
of the R/W signal processor
33
. The decoded signal is fed through the controller
4
and I/F circuit
7
to the host.
The servo controller
6
and microprocessor
5
control the magnetic head
10
to be positioned on the magnetic recording medium
1
and control the medium
1
to be rotated. In the data side servo system, part of the data read from the medium
1
is used as servo data. The read data reproducer
9
extracts this servo data signal, H from the input data and used to control the magnetic head
10
to be positioned.
Also, the R/W signal processor
33
has a register, though not shown, by which the characteristics of respective portions can be switched. This register can be set in a programmable manner by a control signal which is, though not shown, fed from the microprocessor
5
.
FIG. 17
is a block diagram of one example of the R/W amplifier
32
and R/W signal processor
33
shown in FIG.
16
.
Referring to
FIG. 17
, the R/W amplifier
32
is comprised of a read amp. and write driver
11
, a ½ prescaler
12
, a read/write selector
13
, a read buffer amplifier
14
, and a write current source
15
. The read amp. and write driver
11
is connected to the magnetic head
10
and has amplifiers and drivers of which the numbers are equal to that of the magnetic head. The R/W signal processor
33
has the write data generator
38
and read data reproducer
9
, and the write data generator
38
has a write precompensation circuit
38
a
and an encoder
38
b.
The record data E supplied from the host through the I/F circuit
7
and controller
4
shown in
FIG. 16
is converted by the encoder
38
b
into a recording code such as 1-7RLLC or 8/9GCR which is, as shown in FIG.
18
(
a
), suitable for being recorded on the magnetic recording medium. This recording code is further processed to be a data pulse signal C, or shifted in edge phase at each data pattern, by the write precompensation circuit
38
a
in order that the peak shift due to the magnetization interference or the like can be reduced. The data pulse signal C is fed to the R/W amplifier
32
. The data pulse signal C is a serial RZ (return-to-zero) code as shown in FIG.
18
(
b
).
This data pulse signal C is converted by the ½ prescaler
12
of the R/W amplifier
32
into a NRZI (non-return-to-zero-inverted) code K as shown in FIG.
18
(
c
). The current pulse according to this code K is supplied from the write driver
11
to the magnetic head
10
. As a result, data is recorded on the magnetic recording medium
1
shown in FIG.
16
.
In general, since the R/W amplifier
32
is located close to the magnetic head
10
, the R/W amplifier
32
and the R/W signal processor
33
are separate integrated circuits (ICs) and connected by a film-shaped cable.
The read/write selector
13
is a switching circuit for read and write operations. It stops the operation of the write driver at the time of reading and stops the operation of the read amplifier at time of writing. The write current source
15
is used to set the output current from the write driver.
The read buffer amplifier
14
amplifies the analog read data signal from the read amplifier
11
and transmits it to the read data reproducer
9
. The read data reproducer
9
reproduces the read data from the read signal D fed from the read buffer amplifier
14
, decodes the recording code into the original data and supplies it to the controller
4
shown in FIG.
16
.
The write data C transmitted between the R/W signal processor
33
and the R/W amplifier
32
is in the form of TTL or ECL level voltage.
The read data signal D transmitted between the R/W signal processor
33
and the R/W amplifier
32
is also in the form of an analog voltage level.
The magnetic disk player has been so far improved year after year in its data transfer speed. In order to further speed up the data transfer operation, it is necessary to consider the system for transmitting write data signal and read data signal between the R/W signal processor IC
33
and the R/W amplifier IC
32
.
The film cable used for connecting these ICs has a low transmission capability, or it easily dulls the waveform of the high-frequency pulse signal.
The reason is that the cable is necessary to be flexible for easy mounting in the recording and reproducing apparatus and to be inexpensive for low cost of the apparatus, with the result that the cable has a high characteristic impedance and large loss in its conductor and insulator.
FIG. 19
shows the waveforms of write data pulse signal in the conventional magnetic disk player. When the write data train (1, 1, 0, 0, 1) of the recording code as shown in FIG.
19
(
a
) is transmitted at high speed, the ideal pulse waveform is shown in FIG.
19
(
b
), but the actual waveform is blunt as shown by the solid line in FIG.
19
(
c
). When the blunt read signal is shaped in its waveform by the R/W amplifier
32
, the obtained pulse signal is shifted in the phase relation between the leading and trailing edges as shown in FIG.
19
(
d
). This phase shift is caused according to the crowded or scattered pulses (the distance between “1” bits) of the original data pattern shown in FIG.
19
(
a
). In addition, the amplitude is reduced so that the level margin is decreased, causing error in data.
The data transfer speed of the magnetic disk player or the like has recently increased up to 10 MB/sec or above, and thus the specification for the timing margin has become strict. In the present magnetic disk player, since the RZ coding system is used for the write data transmission between the R/W signal processor IC and the R/W amplifier IC, the write data frequency at a transfer speed of 10 MB/sec is 90 MHz for 8/9GCR and 60 MHz for 1-7RLLC.
In the present magnetic disk player having a film cable of about 100-mm in length and connectors, the write data transmission line between the R/W signal processor IC and the R/W amplifier IC has an inductance component of 100 nH and a capacitance component of 20 pF or above considering the conductors on the wiring board and the input/output terminals of ICs, and thus the transmission frequency is limited to about 100 MHz even for ECL level. Therefore, in the present system, data cannot be transferred at a high speed of 20 MB/sec or above.
Also, even if a high-performance cable with the above drawback obviated is used, a high-speed drive buffer is needed and thus the consumption power and cost are increased.
In addition, there has been U.S. Pat. No. 5,404,250 as a related art.
SUMMARY OF THE INVENTION
It is an object of the invention to provide a magnetic recording and reproducing apparatus with the above problems solved, or capable of reducing the consumption power and
Ashikawa Kazutoshi
Hirooka Tsuguyoshi
Miyazawa Shoichi
Mori Masashi
Saiki Eisaku
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