Dynamic magnetic information storage or retrieval – Automatic control of a recorder mechanism – Controlling the head
Reexamination Certificate
1999-12-09
2003-09-23
Hudspeth, David (Department: 2651)
Dynamic magnetic information storage or retrieval
Automatic control of a recorder mechanism
Controlling the head
Reexamination Certificate
active
06624962
ABSTRACT:
FIELD OF THE INVENTION
The invention relates to a storage device for use as an external storage device of a computer or the like and a method for controlling the storage device. More particularly, this invention relates to a storage device capable of avoiding a write fault error or read error which may be caused in switching from power save mode or migration mode to ordinary mode for read/write.
BACKGROUND OF THE INVENTION
As an external storage device of a computer or the like, a storage device employing a circular magnetic disk as a recording medium is used. In such a storage device, reduction of power consumption is achieved by switching to power save mode in which supply of power to a read/write circuit is stopped or the operating speed is reduced and the like when a command (instruction) is received from a host. Further, in the storage device, if time in which no read/write command is received reaches a predetermined time a migration mode is activated. In this migration mode reading of the servo pattern on the magnetic disk is carried out one by one so as to reduce a time for which a sense current flows, thereby prolonging the life of the magnetic head.
However, when changing from the above power save mode or migration mode back to the ordinary mode there is a tendency that the on-track condition of the magnetic head becomes unstable. It has been known by experience that a write fault error or read error is likely to occur when the on-track condition of the magnetic head becomes unstable. Countermeasure for this phenomenon has been seriously demanded.
FIG. 9
is a block diagram which shows an electrical structure of a conventional storage device
20
. The storage device
20
comprises a head disk assembly (HDA)
110
, a printed circuit board
120
and a connector
140
. The hard disk assembly
110
is configured with sealing magnetic disks magnetic disks
111
1
-
111
n
, magnetic heads
113
1
-
113
m
and the like in a container formed of base and cover. The printed circuit board
120
incorporates various circuits such as (HDC) circuit
121
and micro processing device (MPU)
124
. The connector
140
electrically connects components in the HDA
110
to the printed circuit board
120
.
The storage device
20
is connected to the CPU
150
provided in a not illustrated host system. This storage device
20
reads/writes to the magnetic disks
111
1
-
111
n
according to a read/write command from the CPU
150
. The command from the CPU
150
also includes power save mode switching command for switching from the ordinary mode to the previously described power save mode.
n sheets of circular recording mediums as the magnetic disks
111
1
-
111
n
are provided in the HDA
110
for magnetically storing the data. These magnetic disks
111
1
-
111
n
are provided in such a way that they overlay each other with a constant gap between in an axial direction. A spindle motor (SPM)
112
rotates the aforementioned magnetic disks
111
1
-
111
n
at high speed. Each of the magnetic heads
113
1
-
113
m
comprises a head core having a very small gap and a coil wound around the head core. These magnetic heads
113
1
-
113
m
are arranged respectively near the magnetic disks
111
1
-
111
n
.
The magnetic heads
113
1
-
113
m
write data into the magnetic disks
111
1
-
111
n
using the magnetic field generated by a recording current supplied to their coil at the time of writing, whereas they magnetically detect data which is recorded in the magnetic disks
111
1
-
111
n
as a reproduced current. The number m of these magnetic heads
113
1
-
113
m
is appropriately selected depending on the number n of the magnetic disks
111
1
-
111
n
.
A carriage
114
is provided in the vicinity of the magnetic disks
111
1
-
111
n
so as to support the magnetic heads
113
1
-
113
m
. A voice coil motor (VCM)
115
rotates the carriage
114
to move the magnetic heads
113
1
-
113
m
. A flexible print circuit sheet (FPC)
116
is a sheet-like flexible wiring material for connecting between the carriage
114
and each not illustrated terminal of a connector
140
.
A head integrated circuit (IC)
117
is composed of a write amplifier and a not illustrated preamplifier and arranged in parallel on the surface of the FPC
116
. The write amplifier changes over the polarity of the recording current to be supplied to the magnetic heads
113
1
-
113
m
depending on write data supplied from the CPU
150
and the preamplifier amplifies reproduction voltage (read signal) detected by the magnetic heads
113
1
-
113
m
.
A printed circuit board
120
is an externally mounted board attachable to/detachable from a rear face of the HDA
110
via a connector
140
. The connector
140
ensures an interface between components of the HDA
110
and various circuits mounted on the printed circuit board
120
. In the printed circuit board
120
, the HDC circuit
121
is connected to the CPU
150
through an interface such as not illustrated small computer system interface (SCSI) bus or the like so as to send/receive various commands (read command, write command and the like), write data to be written into the magnetic disks
111
1
-
111
n
read data read out from the magnetic disks
111
1
-
111
n
and the like. The HDC circuit
121
generates a control signal or the like for controlling a format for recording/reproduction in the magnetic disks
111
1
-
111
n
or the like.
A flash read only memory (FROM)
122
stores programs for read/write control and power supply control to be carried out by the HDC circuit
121
and MPU
124
, and it is accessed by the HDC
121
and the MPU
124
, when the programs are to be executed. The random access memory (RAM)
123
temporarily stores write data input from the CPU
150
, read data read out from the magnetic disks
111
1
-
111
n
and various data generated during execution of the above program.
A read channel
125
comprises a modulation circuit for writing write data to the magnetic disks
111
1
-
111
n
, a parallel/serial conversion circuit for converting parallel write data to serial data, a demodulation circuit for reading read data from the magnetic disks
111
1
-
111
n
and the like. Further, the read channel
125
comprises a serial/parallel conversion circuit for converting serial read data to parallel data, a synthesizer circuit for generating a timing signal for respective parts of the device by multiplying the frequency of an oscillation circuit using a crystal oscillator and the like.
The MPU
124
controls respective parts of the device and its main control includes read/write control, power save mode control, migration mode control and the like. A detail of an operation of this MPU
124
will be described later. A servo demodulation circuit
126
demodulates servo pattern for positioning stored in the magnetic disks
111
1
-
111
n
by peak hold, integration or the like. A voile coil motor (VCM) driving circuit
127
drives the VCM
115
and is provided with a not illustrated power amplifier for supplying a driving current to the VCM
115
through a connector
140
. A spindle motor (SPM) driving circuit
128
drives the SPM
112
and is provided with a not illustrated power amplifier (for supplying a driving current via the connector
140
.
The MPU
124
recognizes a servo pattern demodulated by the servo demodulation circuit
126
and controls the position of the magnetic head
113
1
-
113
m
by controlling each of driving currents in the VCM driving circuit
127
and SPM driving circuit
128
. Further, the MPU
124
controls the HDC circuit
121
, read channel
125
, head IC
117
and the like. A power source
129
supplies electric power to the respective parts of the device. The MPU
124
controls an electric power supply from the power source
129
.
Next, an operation of the conventional storage device
20
will be described. Hereinafter, mainly read/write operation immediately after transfer from the power save mode to ordinary mode and read/write operation immediately after transfer from migration mode to ordinary mode will be described. When electric power is supplie
Kodama Tohru
Urata Yukio
Greer Burns & Crain Ltd.
Hudspeth David
Slavitt Mitchell
LandOfFree
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