Dynamic magnetic information storage or retrieval – Automatic control of a recorder mechanism – Controlling the record
Reexamination Certificate
1999-08-18
2003-02-04
Sniezek, Andrew L. (Department: 2651)
Dynamic magnetic information storage or retrieval
Automatic control of a recorder mechanism
Controlling the record
C360S074100, C360S078040
Reexamination Certificate
active
06515817
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a magnetic disk drive in which the rotation of the spindle motor is halted or stopped for the purpose of achieving lower power consumption In particular, the invention relates to a magnetic disk drive for reducing the recovery time from the stopped or halted condition of the spindle motor to a rotational speed at which read and write can be performed.
2. Description of the Related Art
A head of a magnetic disk drive moves in the radial direction during rotation of the disk, and is accurately positioned to a target data track for performing read and write of information magnetically.
FIG. 1
shows a sectional diagram of the configuration of a typical magnetic disk drive, which includes six heads
11
, three disks
12
-
1
,
12
-
2
,
12
-
3
and a rotary actuator
13
that are stored in an enclosure. The heads
11
are supported by the rotary actuator
13
and are driven by a voice coil motor
14
. Read and write are performed on both sides of the disks
12
-
1
,
12
-
2
and
12
-
3
, respectively. A package board
17
having the main part of the electronic circuits for controlling the magnetic disk drive is placed outside of the enclosure.
FIG. 2
shows a plan view indicating a configuration of an enclosure of a magnetic disk drive. A disk
12
rotates around an axis A in the direction indicated by an arrow, at the speed of several thousand rotations per minute. A rotary actuator
13
is driven by a voice coil motor, performs a reciprocating rotation motion pivotally around a position B and can move head
11
in the radial direction of the disk
12
as indicated by an arrow. Head preamplifier
15
for read and write, which is a part of the electronic circuits are not placed on a package board
17
of
FIG. 1
, is shown in this figure.
FIG. 3
shows a partial plan view of a magnetic disk drive including a data track
16
, a magnetic disk
12
and a head
11
of a rotary actuator
13
. Servo information for representing the positioning information of the head
11
is written on the magnetic disk
12
beforehand, for example at the factory. The electric power supplied to the voice coil motor is based upon the positioning information and is regulated to achieve accurate positioning of the head
11
for a target track
16
which is performed via a rotary actuator
13
. The head positioning process for the target track is called a following operation. While the following operation is performed, the read and write of information are performed magnetically. Although tracks
16
-
1
,
16
-
2
,
16
-
3
,
16
-
4
and
16
-
5
are indicated respectively by a solid line in
FIG. 3
, these tracks
16
-
1
through
16
- are produced by magnetic information and cannot be recognized optically. Since these tracks number more than ten thousand on the disk
12
, the tracks have a much greater density than as shown in FIG.
3
.
An operation for halting or stopping the rotation of the spindle motor for the purpose of reducing power consumption of the magnetic disk drive is widely employed in portable computers. For instance, the ATA interface standard standardized in X39.2 of ANSI sets forth an automatic power down sequence as a standard. According to this standard, the spindle motor is automatically halted and the power consumption is reduced when a data transfer request does not occur within a time predetermined by the user in a stand-by timer.
FIG. 4
shows a time chart of an automatic power down sequence. At first the disk is stopped in a stand-by status
40
and a host machine issues a command
35
for a magnetic disk drive to start rotation of a disk. In response, the magnetic disk drive performs the start of disk spin-up
30
. The time it takes for increasing rotation of the disk in a process waiting time
37
and a status beginning from an end of the disk spin-up
31
is called an active status
41
. Since the magnetic disk drive can perform read and write of data only in the active stat us
41
, a command issued from the host machine is implemented in an execution time
38
as shown in FIG.
4
. If the host machine does not issue an instruction after the issuance of the instruction
35
before elapse of the stand-by timer setting time, the start of disk spin-down
32
is executed to achieve stand-by status
42
at the end of disk spin down
33
. Then, another start of disk spin-up
34
is executed when a command
36
is issued by the host processor. The process of issuing a command
35
and a next command
36
is a repetitive one.
FIG. 5
shows a time chart detailing the process from issuing a command
35
to waiting time
37
and execution time
38
, as shown in FIG.
4
. In an initial processing
52
soon after receiving the issuance of a read command
51
from the host machine, an interface circuit performs an instruction analysis, a system clock is initiated and a microprocessor is started up. Thereafter, there is the start of disk spin-up
68
for applying electric power to the spindle motor. Start-up rotation continues through a disk spin-up sequence
53
to an end of disk spin-up
69
. At this time, a disturbance measurement
54
is performed for compensating for a disturbance added to an actuator in performing seek accurately. A main cause of the disturbance resides in the non-uniform wiring for a head mounted on the actuator or a voice coil motor and a non-uniform magnetic field in the magnet. Because the disturbance is influenced by the angle of the actuator or the ambient temperature, it is preferable to measure the disturbance under the circumstance where the hard disk drive is normally used. In an actual measurement, a method for repeating a dummy seek several times at different radial positions on the disk is often used and usually a method for performing the dummy seek not only at the time of starting up the disk but also at constant time intervals is employed in general. A seek
55
for a target track is performed after the disturbance measurement is performed. An actual read execution
56
is performed and the process moves to an end of the read command
57
after an end of the seek is confirmed. The time for the process from the issuance of the write command
61
to the end of execution of the write command
67
is the same as the time for the process from the issuance of read command
51
to the end of execution of the read command
57
.
The time from the issuance of the read command
51
or the issuance of the write command
61
for the magnetic disk drive when it is in a stand-by status to the end of execution of the read command
57
or the end of execution of the write command
67
includes the time for the disk spin-up sequences
53
or
63
which are longer than the actual execution time for the read and write
56
,
66
. For data having 256 sectors, and for a magnetic disk drive using a glass disk approximately 63 mm in diameter which is typically used in a portable PC, the time for the read execution
56
and the write execution
66
is approximately 30 ms. Further, the time for performing the disk spin-up sequences
53
or
63
is approximately 1500 ms.
SUMMARY OF THE INVENTION
It is necessary for a long disk spin-up time for a magnetic disk drive under a stand-by status. Therefore, when an automatic power down sequence is in operation and a spindle motor is halted, despite the write command execution or the read command execution of a small number of sectors, a time of about a second is required and deterioration in the performance of the disk drive results. Based upon the access performance of the magnetic disk drivel it is preferred that the disk spin-up time be made shorter. A reduction of the disk spin-up time can be realized by increasing the electric power applied to the spindle motor or by maintaining a low normal operation rotation speed of the disk drive. However, the upper limit of electric power consumed by the magnetic disk drive is often restricted in a portable PC and the electric power applied to the spindle motor cannot be increased. From the viewpoint of
Hamaguchi Takehiko
Matsushita Toru
Takano Hisashi
Tomiyama Futoshi
Hitachi , Ltd.
Mattingly Stanger & Malur, P.C.
Sniezek Andrew L.
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