U.S. patent application number 09/757250 was filed with the patent office on 2001-05-17 for removable type magnetic recording/reproducing device.
This patent application is currently assigned to Mitsumi Electric Co., Ltd.. Invention is credited to Itoh, Toshimitsu, Majima, Yoshihide, Shimizu, Toshiharu, Touji, Hidetsugu.
Application Number | 20010001253 09/757250 |
Document ID | / |
Family ID | 26338376 |
Filed Date | 2001-05-17 |
United States Patent
Application |
20010001253 |
Kind Code |
A1 |
Shimizu, Toshiharu ; et
al. |
May 17, 2001 |
Removable type magnetic recording/reproducing device
Abstract
In a motor drive for driving a motor having three-phase coils in
both a high rotation speed mode making the motor at a high rotation
speed and a low rotation speed mode making the motor at a low
rotation speed which is extremely lower than the high rotation
speed, the motor drive comprises a mode selection circuit for
making a connection of the three-phase coils unipolar and bipolar
connections on the high and the low rotation speed modes,
respectively. A frequency generation pattern detects a rotation
speed of the motor. On the basis of the rotation speed detected by
the frequency generation pattern, a combination of a PLL circuit
and a driving transistor drives the motor at the high and the low
rotation speeds on the high and the low rotation speed modes,
respectively.
Inventors: |
Shimizu, Toshiharu; (Tokyo,
JP) ; Majima, Yoshihide; (Hadano-shi, JP) ;
Itoh, Toshimitsu; (Atsugi-shi, JP) ; Touji,
Hidetsugu; (Atsugi-shi, JP) |
Correspondence
Address: |
FRISHAUF, HOLTZ, GOODMAN, LANGER & CHICK, P.C.
25th Floor
767 Third Avenue
New York
NY
10017-2023
US
|
Assignee: |
Mitsumi Electric Co., Ltd.,
Tokyo
JP
|
Family ID: |
26338376 |
Appl. No.: |
09/757250 |
Filed: |
January 9, 2001 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
09757250 |
Jan 9, 2001 |
|
|
|
09005423 |
Jan 9, 1998 |
|
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Current U.S.
Class: |
360/69 ;
G9B/19.017; G9B/19.042 |
Current CPC
Class: |
G11B 19/26 20130101;
H02P 23/183 20160201; G11B 19/12 20130101 |
Class at
Publication: |
360/69 |
International
Class: |
G11B 015/675 |
Foreign Application Data
Date |
Code |
Application Number |
Jan 14, 1997 |
JP |
4568/1997 |
Jan 14, 1997 |
JP |
4717/1997 |
Claims
What is claimed is:
1. A motor drive for driving a motor having three-phase coils in
both a high rotation speed mode making said motor at a high
rotation speed and a low rotation speed mode making said motor at a
low rotation speed which is extremely lower than the high rotation
speed, said motor drive comprising: mode selection means for making
a connection of the three-phase coils unipolar and bipolar
connections on the high and the low rotation speed modes,
respectively; rotation speed detecting means for detecting a
rotation speed of said motor; and driving means, connected to said
mode selection means and said rotation speed detecting means, for
driving, on the basis of the rotation speed detected by said
rotation speed detecting means, said motor at the high and the low
rotation speeds on the high and the low rotation speed modes,
respectively.
2. A motor drive as claimed in claim 1, wherein said rotation speed
detecting means comprises a frequency generation pattern formed on
a stator of said motor.
3. A motor drive as claimed in claim 1, wherein the high rotation
speed is a rotation speed ten times or more as large as the low
rotation speed.
4. A motor drive as claimed in claim 3, wherein the high rotation
speed has the number of revolution of 3,600 rpm, the low rotation
speed has the number of revolution of 300 rpm.
5. A motor drive as claimed in claim 3, wherein the high rotation
speed has the number of revolution of 3,600 rpm, the low rotation
speed has the number of revolution of 360 rpm.
6. A motor drive as claimed in claim 1, wherein said motor is a
spindle motor.
7. In a high-density/low-density compatible type flexible disk
drive for enabling to carry out data recording and reproducing
operation to and from disk-shaped magnetic recording media of both
a large-capacity and a small-capacity flexible disks, the magnetic
recording medium of the large-capacity flexible disk requiring to
rotate at a high rotation speed on recording and reproducing, the
magnetic recording medium of the small-capacity flexible disk
requiring to rotate at a low rotation speed which is extremely
lower than the high rotation speed on recording and reproducing,
said high-density/low-density compatible type flexible disk drive
comprising a motor having three-phase coils for driving the
magnetic disk media of both the large-capacity and the
small-capacity flexible disks and a motor drive for driving said
motor in both a high rotation speed mode making said motor at the
high rotation speed and a low rotation speed mode making said motor
at the low rotation speed, wherein said motor drive comprising:
mode selection means for making a connection of the three-phase
coils unipolar and bipolar connections on the high and the low
rotation speed modes, respectively; rotation speed detecting means
for detecting a rotation speed of said motor; and driving means,
connected to said mode selection means and said rotation speed
detecting means, for driving, on the basis of the rotation speed
detected by said rotation speed detecting means, said motor at the
high and the low rotation speeds on the high and the low rotation
speed modes, respectively.
8. A high-density/low-density compatible type flexible disk drive
claimed in claim 7, wherein said rotation speed detecting means
comprises a frequency generation pattern formed on a stator of said
motor.
9. A high-density/low-density compatible type flexible disk drive
as claimed in claim 7, wherein the high rotation speed is a
rotation speed ten times or more as large as the low rotation
speed.
10. A high-density/low-density compatible type flexible disk drive
as claimed in claim 9, wherein the high rotation speed has the
number of revolution of 3,600 rpm, the low rotation speed has the
number of revolution of 300 rpm.
11. A high-density/low-density compatible type flexible disk drive
as claimed in claim 9, wherein the high rotation speed has the
number of revolution of 3,600 rpm, the low rotation speed has the
number of revolution of 360 rpm.
12. A high-density/low-density compatible type flexible disk drive
as claimed in claim 7, wherein said motor is a spindle motor.
13. A removable type magnetic recording/reproducing device for
enabling to removably access a large-capacity flexible disk
comprising a disk-shaped magnetic recording medium and a shell for
receiving the disk-shaped magnetic recording medium, the shell
having large-capacity identifier means for identifying the
large-capacity flexible disk in distinction from a
different-capacity flexible disk, said disk-shaped magnetic
recording medium comprising a plurality of tracks thereon which are
arranged with concentric circles around a center of rotation
thereof, each track being divided in a circumferential direction
into a predetermined number of sectors having a length equal to one
another, said plurality of tracks being separated in a radial
direction into a user data area which is available to a user and an
alternate area other than the user data area, said alternate area
having a specific sector for storing capacity information
indicative of a storage capacity of said disk-shaped magnetic
recording medium, wherein said removable type magnetic
recording/reproducing device comprises: large-capacity detecting
means disposed at a position corresponding to said large-capacity
identifier means; and means, connected to said large-capacity
detecting means, for recognizing the storage capacity of said
disk-shaped magnetic recording medium by reading the capacity
information out of the specific sector on said disk-shaped magnetic
recording medium of the large-capacity flexible disk.
Description
BACKGROUND OF THE INVENTION
1. This invention relates to a removable type magnetic
recording/reproducing device such as a flexible or floppy disk
drive (which may be abbreviated to "FDD") and a motor driving unit
for use in the FDD.
2. As is well known in the art, the FDD of the type described is a
device for carrying out data recording and reproducing operation to
and from a magnetic disk medium of a flexible or floppy disk (which
may be abbreviated to "FD") loaded therein. In recent years, the
FDs are more and more improved to have a larger storage capacity.
Specifically, development is made of the FDs having the storage
capacity of 128 Mbytes (which may be called large-capacity FDs) in
contrast with the FDs having storage capacity of 1 Mbyte or 2
Mbytes (which may be called small-capacity FDs). Following such
development, the FDDs have also improved to accept the
large-capacity FDs for data recording and reproducing operations to
and from the magnetic disk media of the large-capacity FDs.
Furthermore, the large-capacity FDs are more improved to have a
larger storage capacity of 256 Mbytes, 512 Mbytes, . . . , and so
on.
3. Throughout the present specification, FDDs capable of
recording/reproducing data for magnetic disk media of the
large-capacity FDs alone will be referred to high-density exclusive
type FDDs. On the other hand, FDDs capable of recording/reproducing
data for magnetic disk media of the small-capacity FDs alone will
be called low-density exclusive type FDDs. Furthermore, FDDs
capable of recording/reproducing data for magnetic disk media of
both the large-capacity and the small-capacity FDs will be called
high-density/low-density compatible type FDDs. In addition, the
high-density exclusive type FDDs and the high-density/low-density
compatible type FDDs will collectively be called high-density type
FDDs.
4. The low-density exclusive type FDD and the high-density type FDD
are different in mechanism from each other in several respects, one
of which will presently be described. In either FDD, a magnetic
head is supported by a carriage which is driven by a drive
arrangement to move in a predetermined radial direction with
respect to the magnetic disk medium of the FD loaded in the FDD.
The difference resides in the structure of the drive arrangement.
More specifically, the low-density exclusive type FDD uses a
stepping motor as the drive arrangement. On the other hand, the
high-density type FDD uses a linear motor such as a voice coil
motor (which may be abbreviated to "VCM") as the drive
arrangement.
5. Now, description will be made in slightly detail as regards the
voice coil motor used as the drive arrangement in the high-density
type FDD. The voice coil motor comprises a voice coil and a
magnetic circuit. The voice coil is disposed on the carriage at a
rear side and is wound around a drive axis extending in parallel to
the predetermined radial direction. The magnetic circuit generates
a magnetic field in a direction intersecting that of an electric
current flowing through the voice coil. With this structure, by
causing the electric current to flow through the voice coil in a
direction intersecting that of the magnetic field generated by the
magnetic circuit, a drive force occurs in a direction extending to
the drive axis on the basis of interaction of the electric current
with the magnetic field. The drive force causes the voice coil
motor to move the carriage in the predetermined radial
direction.
6. Another difference between the low-density exclusive type FDD
and the high-density type FDD resides in the number of revolution
of a spindle motor for rotating the magnetic disk medium of the FD
loaded therein. More specifically, the low-density exclusive type
FDD may rotate the magnetic disk medium of the small-capacity FD
loaded therein at a low rotation speed having the number of
revolution of either 300 rpm or 360 rpm. On the other hand, the
high-density type FDD can admit, as the FD to be loaded thereinto,
either the large-capacity FD alone or both of large-capacity FD and
the small-capacity FD. As a result, when the large-capacity FD is
loaded in the high-density type FDD, the spindle motor for the
high-density type FDD must rotate the magnetic disk medium of the
large-capacity FD loaded therein at a high rotation speed having
the number of revolution of 3600 rpm which is equal to ten or
twelve times as large as that of the small-capacity FD.
7. In the meanwhile, the large-capacity FD generally has an
external configuration identical with that of the small-capacity
FD. Specifically, both of the large-capacity and the small-capacity
FDs have a flat rectangular shape of a width of 90 mm, a length of
94 mm, and a thickness of 3.3 mm in case of a 3.5-inch type.
However, the large-capacity FD has a narrower track width (track
pitch) than that of the small-capacity FD. As a result, it is
difficult for the large-capacity FD to position a magnetic head of
the high-density type FDD on a desired track in the magnetic disk
medium thereof in contrast with the small-capacity FD. Accordingly,
a servo signal for position detection is preliminarily written in
the magnetic disk medium of the large-capacity FD.
8. In addition, it is necessary for the high-density/low-density
compatible type FDD to identify and detect whether the FD loaded
therein is the large-capacity FD or the small-capacity FD.
9. In the meanwhile, the FD being about to manufactured (which will
be called a raw FD) comprises merely a magnetic disk medium having
both surfaces coated with magnetic material. In order to enable to
make the row FD utilize for an electronic device such as a personal
computer or a word processor, it is necessary for the raw FD to
partition the magnetic disk medium into a plurality of regions with
addresses and to record and manage what information should be
written in each region. Such a sequence of processing steps is
called a format(ting) or an initialization.
10. In general, the FD comprises the magnetic disk medium on which
a plurality of tracks which are arranged with concentric circles
around a center of rotation thereof. The tracks may arranged with a
spiral fashion around the center of rotation. Each track is divided
in a circumferential direction into a predetermined number of
sectors having a length equal to one another.
11. The formatting is classified into a physical formatting and a
logical formatting. The physical formatting determines how data is
arranged on the magnetic disk medium. Specifically, the physical
formatting determines the total tracks, the total usable tracks,
the number of sectors in each track, a medium storage capacity, a
format storage capacity, and so on. On the other hand, the logical
formatting determines locations where information corresponding to
table of contents is written on the magnetic disk medium and
assigns addresses to units each of which writes information. The
logical formatting is also called a sector formatting.
12. More specifically, the sector formatting is performed by using
a servo writer and a media formatter. The servo writer partitions
first each sector into a servo field and a data field to write the
above-mentioned servo signal in the servo field. In this event, the
sectors on each track are assigned with sector numbers in the
circumferential direction in order. Thereafter, the media formatter
carries out test of the sector format and preparation of a
defective map. Specifically, not that all of the tracks on the
magnetic disk medium can be used by a user, an area available to
the user is restricted. Such an area is referred to as a user data
area. Tracks other than the user data area are used as alternate
tracks for alternate sectors for replacing defective sectors in the
user data area. Such an area for the alternate tracks is an
alternate area. The alternate area is generally disposed in the
magnetic disk medium in a radial direction on the inward side. In
addition, separation of the tracks into the user data area and the
alternate area is carried out by the physical formatting. The media
formatter first performs test of the sector format to detect the
defective sectors on the user data area. Subsequently, the media
formatter carries out rearrangement of the sectors except for the
defective sectors. Thereafter, the media formatter prepares a
defective map. The defective map is a table for entering
information indicating where the defective sectors on the user data
area are arranged to which alternate sectors in the alternate area.
The defective map is stored in a predetermined sector in the
alternate area. If the storage capacity of a sector-formatted FD is
less than a predetermined specification storage capacity due to the
presence of a lot of defective sectors, the sector-formatted FD is
discarded because the sector-formatted FD cannot be used.
13. As described above, there are various types of the
large-capacity FDs so as to have the storage capacity of 128 Mbytes
or 256 Mbytes. Throughout the present specification, the
large-capacity FD having the storage capacity of 128 Mbytes is
called a single-density large-capacity FD while the large-capacity
FD having the storage capacity of 256 Mbytes is called a
double-density large-capacity FD. Although each of the
single-density large-capacity FD and the double-density
large-capacity FD has the same line recording density, the same
sector format (servo format), and the same number of disk
revolution, the single-density large-capacity FD and the
double-density large-capacity FD have different track densities
from each other. That is, the double-density large-capacity FD has
the track density twice as large as that of the single-density
large-capacity FD. In addition, the high-density type FDDs capable
of recording/reproducing data for magnetic disk media of the
single-density large-capacity FDs will be referred to as
single-density large-capacity type FDDs. On the other hand, the
high-density type FDs capable of recording/reproducing data for
magnetic disk media of the double-density large-capacity FDs will
be referred to as double-density large-capacity type FDDs.
14. It is assumed that data are read from the magnetic disk medium
of the double-density large-capacity FD by the magnetic head of the
single-density large-capacity type FDD. In this event, an output
level of the read data is a half of that obtained when data on the
magnetic disk medium of the single-density large-capacity FD is
read by the magnetic head of the single-density large-capacity type
FDD. In addition, it is assumed that data are read from the
magnetic disk medium of the single-density large-capacity FD by the
magnetic head of the single-density large-capacity type FDD. In
this event, an output level of the read data is equivalent to that
obtained when data on the magnetic disk medium of the
double-density large-capacity FD are read by the magnetic head of
the double-density large-capacity type FDD.
15. On the other hand, it is assumed that data are written in the
magnetic disk medium of the double-density large-capacity FD by the
magnetic head of the single-density large-capacity type FDD. In
this event, a recording level of the data is lower than that
obtained when data on the magnetic disk medium of the
single-density large-capacity FD are written by the magnetic head
of the single-density large-capacity type FDD. In addition, it is
presumed that data are written in the magnetic disk medium of the
single-density large-capacity FD by the magnetic head of the
double-density large-capacity type FDD. In this event, a recording
level of the data is equivalent to that obtained when data on the
magnetic disk medium of the double-density large-capacity FD are
written by the magnetic head of the double-density large-capacity
type FDD.
16. However, once data are written in the magnetic disk medium of
the single-density large-capacity FD by the magnetic head of the
double-density large-capacity type FDD, the data on the magnetic
disk medium of the single-density large-capacity FD only have a
recording level equivalent to that of the magnetic disk medium of
the signal-density large-capacity FD. As a result, when that data
on the magnetic disk-medium of the single-density large-capacity FD
are read by the magnetic head of the single-density large-capacity
type FDD, the read data have an output level which is a half of a
normal output level. Accordingly, reading of data on the magnetic
disk medium of the single-density large-capacity FD by the
double-density large-capacity type FDD is no problem, but writing
of data on the magnetic disk medium of the single-density
large-capacity FD by the double-density large-capacity type FDD is
a problem. It is therefore necessary to make the double-density
large-capacity type FDD have compatibility of reproduction for the
single-density large-capacity FD alone.
17. In view of such necessity, it is necessary for the high-density
type FDD to determine which type the large-capacity FD loaded
therein belongs to.
18. In order to cope with this problem, Japanese Unexamined Patent
Publications of Tokkai (JP-A) Nos. 9-306142 on Nov. 28, 1997,
9-306089 on Nov. 28, 1997, and 9-306143 on Nov. 28, 1997 disclose a
large-capacity flexible disk and a high-density type disk drive
used therefor. In these publications, a case accommodating the
magnetic disk medium of the large-capacity FD is provided not only
with a large-capacity identifier hole or notch for discriminating
the large-capacity FD from a different-capacity FD but also with
selectively formed type identifier holes or notches for identifying
the type of the large-capacity FD. In addition, in these
publications, the high-density type FDD is provided not only with a
large-capacity detecting switch for detecting the presence or
absence of the above-mentioned large-capacity identifier hole or
notch but also with type detecting switches for detecting the
presence or absence of the type identifier holes or notches.
19. However, the above-proposed high-density type FDD is
disadvantageous in that a lot of parts are required because the
high-density type FDD must be provided with the type detecting
switches for detecting the type of the large-capacity FD.
20. In addition, Japanese Unexamined Patent Publications of Tokkai
(JP-A) Nos. 9-320181 on Dec. 12, 1997 and 9-330556 on Dec. 22, 1997
disclose a control method for a spindle motor for a high-density
type flexible disk drive. In these publications, the high-density
type FDD comprises a switch unit for detecting whether a loaded FD
is a large-capacity FD or a small-capacity FD and a control device
for controlling drive of a spindle motor so as to rotate the
spindle motor at a high rotation speed when the loaded FD is
identified as the large-capacity FD and so as to rotate the spindle
motor at a low rotation speed when the loaded FD is identified as
the small-capacity FD.
21. As described above, the high-density/low-density compatible
type FDD must rotate in the high speed mode the spindle motor at
the high rotation speed which is equal to ten or twelve times as
large as that in the low speed mode. In general, it is difficult to
control rotation at a high precision with a desired torque using
the single spindle motor in the two speed modes which have
extremely different rotation speeds.
22. On the other hand, technique enabling to control the rotation
speed at the high precision under a constant rotation speed mode is
already known. For instance, it is possible to control the rotation
speed at the high precision by using a sensorless motor driver in a
case of the high rotation speed which has the number of revolution
of 3,600 rpm. Furthermore, it is possible to control the rotation
speed at the high precision by using an FG motor driver in a case
of the low rotation speed which has the number of revolution of
either 300 rpm or 360 rpm. A three-phase brushless d.c. motor is
used as a motor operable at the constant rotation speed mode. In
addition, there are two methods of connecting windings in the
three-phase brushless d.c. motor, namely, a unipolar connection and
a bipolar connection. The unipolar connection is a connection where
a common connection terminal of three-phase coils is connected to
either a power supply terminal or a ground terminal to allow
current to flow through the coil of each phase. The bipolar
connection is a connection where the common connection terminal of
the three-phase coles is opened to allow current to flow through
two coils at a time. The bipolar connection is used in control of
the number of revolution under the above-mentioned constant
rotation speed mode.
23. A motor drive is proposed in Japanese Unexamined Patent
Publication of Tokkai No. Hei 6-351,283 or JP-A 6-351,283 on Dec.
22, 1994 which is hereby incorporated herein by reference. The
motor drive selectively allows switching of the unipolar connection
and the bipolar connection in order to allow a single motor to
switch a motor characteristics at two rotation speed modes which
are operable at a low speed rotation state and a high speed
rotation state. The motor drive is used, for example, in a portable
magnetic tape recorder to satisfactorily carry out by using the
single motor both of a low-speed (a constant-speed) tape travelling
mode such as reproduction (playback), recording of a tape, or the
like and a high-speed tape travelling mode such as rapid
traversing, rewinding of the tape, or the like. On the low rotation
speed mode (or on the low-speed tape travelling mode such as the
above-mentioned reproduction, recording, or the like), the motor
drive selects the bipolar connection to drive the motor with full
wave and it results in a power-saving effect. On the other hand, on
the high rotation speed mode (or on the high-speed tape travelling
mode such as the above-mentioned rapid traversing, rewinding, or
the like), the motor drive selects the unipolar connection to drive
the motor with half wave and it results decreasing the number of
revolution in the motor.
24. However, it is difficult in the JP-A 6-351,283 to control the
number of revolution (the rotation speed) at the high precision
although it is possible to obtain a necessary torque in each of the
low rotation speed mode and the high rotation speed mode. This is
because it is not necessary for the drive motor to control the
number of revolution at the high precision from the first
particularly at the high rotation speed mode which is used in the
rapid traversing or the rewinding of the tape.
25. For example, it is necessary for the high-density/low-density
compatible type FDD to have the torque equal to or more than 14
g-cm at the high rotation speed mode and to have the torque equal
to or more than 60 g-cm at the low rotation speed mode. In
addition, it is necessary for the high-density/low-density
compatible type FDD to restrain fluctuations in the number of
revolution within 0.2%.
SUMMARY OF THE INVENTION
26. It is therefore an object of this invention to provide a motor
drive which is capable of controlling the number of revolution at a
high precision using a single motor in two rotation speed modes
having rotation speeds which are extremely different from each
other.
27. It is another object of this invention to provide a motor drive
of the type described, which is capable of controlling the number
of revolution with a necessary torque in each of the two rotation
speed modes using the single motor.
28. It is a subordinate object of this invention to provide a
high-density/low-density compatible type flexible disk drive
provides with the above-mentioned motor drive.
29. It is a different object of this invention to provide a
removable type magnetic recording/reproducing device which is
capable of detecting a type of a magnetic recording medium loaded
therein without increase in parts thereof.
30. According to a first aspect of the present invention, a motor
drive drives a motor having three-phase coils in both a high
rotation speed mode making the motor at a high rotation speed and a
low rotation speed mode making the motor at a low rotation speed
which is extremely lower than the high rotation speed. The motor
drive comprises mode selection means for making a connection of the
three-phase coils unipolar and bipolar connections on the high and
the low rotation speed modes, respectively. Rotation speed
detecting means detects a rotation speed of the motor. Connected to
the mode selection means and the rotation speed detecting means,
driving means drives, on the basis of the rotation speed detected
by the rotation speed detecting means, the motor at the high and
the low rotation speeds on the high and the low rotation speed
modes, respectively.
31. According to a second aspect of the present invention, a
high-density/low-density compatible type flexible disk drive
enables to carry out data recording and reproducing operation to
and from disk-shaped magnetic recording media of both a
large-capacity and a small-capacity flexible disks. The magnetic
recording medium of the large-capacity flexible disk requires to
rotate at a high rotation speed on recording and reproducing. The
magnetic recording medium of the small-capacity flexible disk
requires to rotate at a low rotation speed which is extremely lower
than the high rotation speed on recording and reproducing. The
high-density/low-density compatible type flexible disk drive
comprises a motor having three-phase coils for driving the magnetic
disk media of both the large-capacity and the small-capacity
flexible disks and a motor drive for driving the motor in both a
high rotation speed mode making the motor at the high rotation
speed and a low rotation speed mode making the motor at the low
rotation speed. The motor drive comprises mode selection means for
making a connection of the three-phase coils unipolar and bipolar
connections on the high and the low rotation speed modes,
respectively. Rotation speed detecting means detects a rotation
speed of the motor. Connected to the mode selection means and the
rotation speed detecting means, driving means drives, on the basis
of the rotation speed detected by the rotation speed detecting
means, the motor at the high and the low rotation speed on the high
and the low rotation speed modes, respectively.
32. According to a third aspect of the present invention, a
removable type magnetic recording/reproducing device enables to
removably access a large-capacity flexible disk comprising a
disk-shaped magnetic recording medium and a shell for receiving the
disk-shaped magnetic recording medium. The shell has large-capacity
identifier means for identifying the large-capacity flexible disk
in distinction from a different-capacity flexible disk. The
disk-shaped magnetic recording medium comprises a plurality of
tracks thereon which are arranged with concentric circles around a
center of rotation thereof. Each track is divided in a
circumferential direction into a predetermined number of sectors
having a length equal to one another. The plurality of tracks are
separated in a radial direction into a user data area which is
available to a user and an alternate area other than the user data
area. The alternate area has a specific sector for storing capacity
information indicative of a storage capacity of the disk-shaped
magnetic recording medium. The removable type magnetic
recording/reproducing device comprises large-capacity detecting
means disposed at a position corresponding to the large-capacity
identifier means and means for recognizing the storage capacity of
the disk-shaped magnetic recording medium by reading the capacity
information out of the specific sector on the disk-shaped magnetic
recording medium of the large-capacity flexible disk.
BRIEF DESCRIPTION OF THE DRAWING
33. FIG. 1 is a plan view of a high-density type FDD to which this
invention is applicable;
34. FIGS. 2A and 2B collectively show a spindle motor for use in
the high-density type FDD illustrated in FIG. 1;
35. FIGS. 3A and 3B collectively show a large-capacity FD loaded in
the high-density type FDD illustrated in FIG. 1;
36. FIG. 4 is a plan view showing an example of a frequency
generation (FG) pattern formed on a subsidiary printed-circuit
board;
37. FIG. 5 is a block diagram of a motor drive according to an
embodiment of this invention with the spindle motor and a switch
unit;
38. FIG. 6 shows basis torque characteristic curves of the spindle
motor on unipolar and bipolar connections;
39. FIG. 7 is a plan view of another high-density type FDD to which
this invention is applicable;
40. FIGS. 8A and 8B collectively show another large-capacity FD
loaded in the high-density type FDD illustrated in FIG. 7;
41. FIG. 9 is a plan view of a magnetic recording medium for use in
the large-capacity FD illustrated in FIGS. 8A and 8B; and
42. FIG. 10 is a block diagram of a signal system for use in the
high-density type FDD illustrated in FIG. 7.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
43. Referring to FIG. 1, description will proceed to a high-density
type flexible disk drive (FDD) to which this invention is
applicable. The illustrated high-density type FDD is a
high-density/low-density compatible type FDD for enabling to carry
out recording/reproducing of data for magnetic disk media of both a
large-capacity and a small-capacity flexible disks (FDs) which will
later be described. The FD is loaded into the high-density type FDD
from an insertion direction indicated by an arrow A in FIG. 1. FIG.
1 shows a state where the FD is loaded into the high-density type
FDD. The FD has a disk center axis (not shown).
44. The high-density type FDD comprises a main frame 11 having a
main surface 11a and a disk holder table 12 which is rotatably
supported on the main surface 11a of the main frame 11. The disk
holder table 12 has a table center axis O which acts as the axis of
the rotation. The loaded FD is held on the holder disk table 12 so
that the table center axis O coincides with the disk center axis.
The disk holder table 12 is rotatably driven by a spindle motor
(SPM) 100 which will later be described. The spindle motor 100 is
mounted on the main frame 11 with the spindle motor 100 put into a
state embedded in a concave portion (which will later be described)
of the main frame 11, thereby the magnetic disk medium in the FD
rotates at a desired rotation speed in the manner which will become
clear. In addition, the main frame 11 has a back surface (not
shown) on which a printed-circuit board 22 is attached. A number of
electronic parts (not shown) are mounted on the printed-circuit
board 22.
45. The high-density type FDD comprises a pair of magnetic heads
(not shown) for reading/writing data from/to the magnetic disk
medium in the FD. The magnetic heads are supported via gimbals 14
with the carriage 15. A combination of the magnetic heads, the
gimbals 14, the carriage 15, a pair of voice coils 17 (which will
later be described), a scale (not shown), a spring holder, and a
spring is called a carriage assembly. The carriage 15 is disposed
over the main surface 11a of the main frame 11 with a space left
therebetween. The carriage 15 supports the magnetic heads movably
in a predetermined radial direction (i.e. a direction indicated by
an arrow B in FIG. 1) with respect to the FD.
46. The carriage 15 is supported and guided at both lower sides
thereof by a pair of guide bars 16 which extend to directions in
parallel with the predetermined radial direction B.
47. The carriage 15 is driven in the predetermined radial direction
B by a voice coil motor which will later be described. More
specifically, the voice coil motor comprises the pair of voice
coils 17 and a pair of magnetic circuits 20. The voice coils 17 are
disposed on the carriage 15 at a rear side and are wound around
driving axes in parallel with the predetermined radial direction B.
The magnetic circuits 20 generate magnetic fields which intersect
currents flowing in the voice coils 17. With this structure, by
causing the currents to flow in the voice coils 17 in directions
where the magnetic fields generated by the magnetic circuits 20
intersect, driving force occurs along the predetermined radial
direction B extending to the driving axes on the basis of
interaction between the currents and the magnetic fields. The
driving force causes the voice coil motor to move the carriage 15
in the predetermined radial direction B.
48. Referring to FIGS. 2A and 2B, description will proceed to the
spindle motor 100 for use in the high-density type FDD illustrated
in FIG. 1. The spindle motor 100 comprises a rotor and a stator
both of which will later become clear. FIG. 2A is a plan view of
the spindle motor 100. FIG. 2B is a cross-sectional view taken on
line C-C with respect to the rotor and on line D-D with respect to
the stator in FIG. 2A.
49. The illustrated spindle motor 100 is a type mounted on the main
surface 11a of the main frame 11 in place of the back surface of
the main frame 11. In particular, the spindle motor 100 is mounted
on the main surface 11a with the spindle motor 100 embedded in the
concave portion 11b of the main frame 11.
50. The main frame 11 comprises a bearing metal 102 of
substantially cylindrical shape in the concave portion 11b. The
bearing metal 102 stands in the concave portion 11b substantially
perpendicular to the main surface 11a of the main frame 11. With
the bearing metal 102, a spindle shaft 104 is rotatably supported
with respect to the main frame 11 via a ball bearing 106
substantially perpendicular to the main surface 11a of the main
frame 11. The spindle shaft 104 serves as the axis O of the
rotation for the magnetic disk medium of the FD loaded in the
high-density type FDD. The disk holder table 12 is fixed to the
spindle shaft 104 at an upper portion thereof. The disk holder
table 12 has a main surface which extends to a direction
perpendicular to a longitudinal direction (a direction of the axis
O of the rotation) of the spindle shaft 104.
51. That is, the disk holder table 12 is rotatably supported on the
main surface 11a of the main frame 11 and holds the FD loaded in
the high-density type FDD so that the table center axis O (the axis
of the rotation) coincides with the disk center axis of the FD.
52. Turning to FIGS. 3A and 3B, description will proceed to the
large-capacity FD depicted at 40. FIG. 2A is a plan view of the
large-capacity FD as seen from an upper surface side while FIG. 3B
is a bottom view of the large-capacity FD as seen from a lower
surface side. The illustrated large-capacity FD 40 is a 3.5-inch
type and comprises a disk-shaped magnetic recording medium 41
serving as a disk-shaped magnetic recording medium, and a shell or
a case 42 for receiving the magnetic recording medium 41. The shell
42 consists of an upper shell or case (FIG. 3A) having the upper
surface and a lower shell or case (FIG. 3B) having the lower
surface.
53. As shown in FIG. 3B, in the lower surface of the shell 42, a
circular aperture 42a is formed at a center portion of the
large-capacity FD 40. In the circular aperture 42a is freely
received a disk hub (a disk-shaped metal) 43 for holding the
magnetic recording medium 41. The disk hub 43 has a disk center
hole 43a at a center portion thereof and a chucking hole (a disk
driving oval hole) 43b at a position eccentric with the center
portion thereof. The disk center hole 43a has substantially a
rectangular shape and receives the spindle shaft 104 (FIG. 2B)
therein in the manner which will later be described. The chucking
hole 43b freely receives a chucking pin or a drive roller 108 (FIG.
1) therein in the manner which will also later be described.
54. Turning back to FIGS. 2A and 2B, the disk holder table 12 has a
diameter which is longer than that of the disk hub 43 and which is
shorter than that of the circular aperture 42a of the shell 42.
55. The disk holder table 12 has a table driving oval hole 12a at a
position corresponding to the chucking hole (the disk driving oval
hole) 43b (FIG. 3B). Through the table driving oval hole 12a, the
chucking pin (the drive roller) 108 is freely received in the
chucking hole 43b of the FD 40 in the manner which will later
become clear. The table driving oval hole 12a has an inclined
portion 12a-1 as shown in FIG. 2A. The disk holder table 12 is
mounted on a magnetic case 110 at a bottom surface thereof. The
magnetic case 110 has a flexible arm 112 having an end which is
provided with a holding portion 114. The chucking pin 108 is
rotatably and movably mounted on the flexible arm 112 at the end
thereof via the holding portion 114 with the chucking pin 108 urged
upwardly. Accordingly, the chucking pin 108 moves downwardly or
sinks in the disk holder table 12 if any load is applied to the
chucking pin 108 downwards.
56. In the example being illustrate, the magnetic case 110 is made
of iron and is formed in a shape of a tray by presswork. More
specifically, the magnetic case 110 comprises a disk portion 116
and a circumferential wall 118. The disk portion 116 extends in a
direction parallel with the disk holder table 12. The
circumferential wall 118 is bent downwardly at an circumferential
edge of the disk portion 116. The circumferential wall 118 has an
inner surface on which a ring-shaped main magnet 120 is fixed.
57. At any rate, the spindle shaft 104, the disk holder table 12,
the chucking pin 108, the magnetic case 110, the arm 112, the
holding portion 114, and the ring-shaped main magnet 120 compose
the rotor of the spindle motor 100.
58. The bearing metal 102 includes a flange portion 102a. On the
flange portion 102, a core 122 is fixed by screws (not shown) and
is mounted. The core 122 comprises a plurality of magnetic pole
forming sections 112a which extend with equal intervals in a radial
manner. Around each magnetic pole forming section 112a, one of
three-phase coils 124 is wound. That is, a combination of the
magnetic pole forming section 112a and one of the three-phase coils
124 serves as an electromagnet or a magnetic pole. The
electromagnet is opposed to the above-mentioned main magnet 120
with a predetermined space (gap) left therebetween. At any rate,
the core 122 and the three-phase coils 124 compose the stator of
the spindle motor 100.
59. The circumferential wall 118 of the magnetic case 108 has an
outer surface at a predetermined position of which an index
detection magnet 128 (FIG. 1) of rectangular parallelepiped shape
is fixed. In addition, in the concave portion 11b of the main frame
11, a subsidiary printed-circuit board 126 is fixed by screws (not
shown) and is received. Mounted on the subsidiary printed-circuit
board 126, a magnetic sensor (not shown) detects a magnetic field
generated by the index detection magnet 128.
60. Furthermore, the illustrated spindle motor 100 is provided with
a balancer 130 acting as a balance arrangement. The balancer 130 is
mounted on the magnetic case 110 at the lower surface thereof
opposite to the chucking pin 108 with the spindle shaft 104
sandwiched therebetween. As a result, it is possible to balance the
rotor of the spindle motor 100 on rotating (in particular, on
rotating at the high rotation speed) so as to make the center G of
gravity in the rotor coincide with the axis O of the rotation.
61. Referring to FIGS. 3A and 3B again, a write protection hole 44
is bored in the shell 42 of the large-capacity FD 40 at a corner
portion in rear and right-hand side with respect to an insertion
direction depicted at an arrow A of FIG. 3B as view from the lower
surface of the large-capacity FD 40. In other words, the write
protection hole 44 is bored in the shell 42 of the large-capacity
FD 40 at the corner portion in rear and left-hand side in the
insertion direction A of FIG. 3A as viewed from the upper surface
of the large-capacity FD 40. FIG. 3B shows a state where the write
protection hole 44 is shut by a write protection tab 44a. The write
protection tab 44a enables to slide along a direction in parallel
with the insertion direction A. It is possible to carry out opening
and closing of the write protection hole 44 by operating the write
protection tab 44a manually. When the write protection hole 44 is
closed by the write protection tab 44a, the large-capacity FD 40 is
put into a write enable state. When the write protection hole 44 is
opened by the write protection tab 44a, the large-capacity FD is
put into a write disable state.
62. The illustrated large-capacity FD 40 shows a case where there
is two types of storage capacity of, for example, 128 Mbytes and
256 Mbytes. In the vicinity of the write protection hole 44, a
large-capacity identifier hole 45 is bore in the shell 42 of the
large-capacity FD 40. The large-capacity identifier hole 45 is for
identifying the large-capacity FD 40 in distinction from the
small-capacity FD. In addition, a type identifier hole 46 is
selectively bored in the shell 42 of the large-capacity FD 40 near
the write protection hole 44 together with the large-capacity
identifier hole 45. The type identifier hole 46 is for identifying
a type of the large-capacity FD 40. It is possible to identify the
type of the large-capacity FD 40 according to the presence or
absence of the type identifier hole 46. It is assumed that the
large-capacity FD 40 having the storage capacity of 128 Mbytes is
referred to as a first type of the large-capacity FD while the
large-capacity FD 40 having the storage capacity of 256 Mbytes is
referred to as a second type of the large-capacity FD. In the
example being illustrated, the type identifier hole 46 is not bore
in the shell 42 of the first type of the large-capacity FD while
the type identifier hole 46 is bored in the shell 42 of the second
type of the large-capacity FD.
63. Although illustration is omitted, as is well known in the art,
the large-capacity identifier hole 45 and the type identifier hole
46 are not bored in a shell or case of the small-capacity FD.
64. Turning back to FIG. 1 in addition to FIGS. 3A and 3B, on the
printed-circuit board 22 mounted on the back surface of the main
frame 11, the high-density type FDD further comprises a switch unit
50 at a corner position in rear and left-hand side with respect to
the insertion direction A. The switch unit 50 comprises a plurality
of push switches which will presently be described. The switch unit
50 is for detecting the presence or absence of the write protection
hole 44, the large-capacity identifier hole 45, and the type
identifier hole 46.
65. More specifically, the switch unit 50 comprises, as the push
switches, a write control switch 51, a large-capacity detecting
switch 52, and the type detecting switch 53. The write control
switch 51 is a push switch for detecting the opening or closing
state of the write protection hole 44. The control switch 51 is
disposed at a position corresponding to the write protection hole
44 when the large-capacity FD 40 is loaded in the high-density type
FDD. The large-capacity detecting switch 52 is a push switch for
detecting whether the loaded FD is the large-capacity FD or the
small-capacity FD. The large-capacity detecting switch 52 is
disposed at a position corresponding to the large-capacity
identifier hole 45 when the large-capacity FD 40 is loaded in the
high-density type FDD. The type detecting switch 53 is a push
switch for detecting the presence or absence of the type identifier
hole 45. The type detecting switch 53 is disposed at a position
corresponding to the type identifier hole 46 when the
large-capacity FD 40 is loaded in the high-density type FDD.
66. Turning to FIG. 4 in addition to FIG. 2B, a sawtooth conductor
pattern 132 is formed on the subsidiary printed-circuit board 126
around the stator of the spindle motor 100 all over circumference.
The sawtooth conductor pattern 132 is for detecting the rotation
speed of the spindle motor and is therefore called a frequency
generation pattern (which is abbreviated an FG pattern
hereinafter). The FG pattern 132 generates an FG signal having
pulses which in number to sixty during one rotation of the spindle
motor 100. As is well known in the art, 300 rpm is equivalent to 5
Hz/rev while 3,600 rpm is equivalent to 60 Hz/rev. As a result, the
FG pattern 132 generates the FG signal having a frequency of 300 Hz
if the magnetic disk medium of the small-capacity FD rotates at its
prescribed rotation speed of 300 rpm by the spindle motor 60.
Likewise, the FG pattern generates the FG signal having a frequency
of 3,600 Hz if the magnetic disk medium of the large-capacity FD 40
rotates at its prescribed rotation speed of 3,600 rpm by the
spindle motor 100.
67. On the other hand, as described above, the rotor of the spindle
motor 100 comprises the magnetic case 110 and the ring-shaped main
magnet 120 attached to the inner surface thereof. The ring-shaped
main magnet 120 is position on the FG pattern 132 with its inner
peripheral end surface confronting pole horns of the magnetic pole
forming sections 112a of the core 122. The ring-shaped main magnet
120 has a plurality of equiangularly split regions in a
circumferential direction and is subjected to split magnetization
such that N poles and S poles appear in these regions on its
internal side wall and that the polarity is alternately
reversed.
68. Although the FG pattern 132 is formed on the subsidiary
printed-circuit board 126 all over circumference in the example
being illustrated, the FG pattern 132 may be formed on the
subsidiary printed-circuit board 126 in an area defined by a
predetermined angular range, for example, between 180.degree. and
270.degree..
69. Turning back to FIGS. 3A and 3B, the large-capacity FD 40
further comprises a shutter 47 at a front side thereof. The shutter
47 is slidable in a direction depicted at E in FIGS. 3A and 3B. The
shutter 47 is provided with a window 47a. The shutter 47 is urged
by a spring (not shown) in a direction reverse to the direction E.
When the shutter 47 makes sliding movement in the direction E, the
window 47a of the shutter 47 is faced to an opening 42b formed in
the shell 42. At this time. it is possible to access the magnetic
recording medium 41 by upper and lower magnetic heads (not shown)
through the opening 42b.
70. Turning back to FIG. 1, the high-density type FDD includes a
shutter drive mechanism for opening and closing the shutter 47 of
the large-capacity FD 40, an ejector mechanism for ejecting the
large-capacity FD 40, and a carriage locking mechanism for locking
a direct-acting type carriage mechanism (which will later be
described) after ejection of the large-capacity FD 40.
71. The high-density type FDD further comprises a lever unit 70.
the lever unit 70 comprises an eject laver 71 and a lock lever 72.
The eject lever 71 serves both as a component of the shutter drive
mechanism for opening and closing the shutter 47 and as a component
of the ejector mechanism for ejecting the large-capacity FD 40 from
the high-density type FDD. The lock lever 72 is located in the
vicinity of the direct-acting type carriage mechanism and serves to
lock the direct-acting type carriage mechanism upon ejection of the
large-capacity FD 40.
72. The ejector mechanism comprises an eject button 54 projecting
into an outer surface of a front bezel (not shown) of the
high-density type FDD, an eject plate 55 for positioning the
large-capacity FD 40 loaded through an insertion slot (not shown)
of the front bezel so that one surface of the large-capacity FD 40
is faced to the eject plate 55, and a pair of eject springs (not
shown) having one end engaged with eject plate 55 and the other end
engaged with a disk holder unit (not shown). The eject plate 55 has
a rack 55a at its top end in a depth direction. The rack 55a is
engaged with a pinion (not shown) rotatably supported on the main
surface 11a of the main frame 11. The lever unit 70 is urged by a
spring mechanism 73 in a counterclockwise direction.
73. It is assumed that the large-capacity FD 40 is loaded into the
disk holder unit of the high-density type FDD. Specifically, when
the large-capacity FD 40 is inserted in the direction depicted at
the arrow A in FIG. 1, a top end 71a of the eject lever 71 is
engaged an upper end 47b of a right side edge of the shutter 47.
With the movement of the large-capacity FD 40, the lever unit 70 is
rotated in a clockwise direction. Consequently, the shutter 47 is
forced by the top end 71a of the eject lever 71 to make sliding
movement in the direction depicted by the arrow C.
74. When the large-capacity FD 40 is completely received in the
disk holder unit of the high-density type FDD, the disk holder unit
comes down and then the large-capacity FD 40 is locked by a disk
lock mechanism (not shown) to be stably held in the disk holder
unit. In this state, engagement between side arms (not shown) of
the carriage assembly and the disk holder unit is released and the
window 47a of the shutter 47 is located directly above the opening
42b of the shell 42. Accordingly, the upper magnetic head is in
contact with the magnetic recording medium 41 of the large-capacity
FD 40 through the window 47a of the shutter 47 and the opening 42a
of the shell 42. The shutter 47 is urged by a spring member (not
shown) to be located at a position indicated by a dash-and-dot line
in FIG. 3A.
75. The high-density type FDD comprises a pair of magnetic heads
for reading/writing data from/to the magnetic recording medium 41
in the large-capacity FD 40. The magnetic heads are supported via
gimbals 14 with a carriage 15. A combination of the gimbals 14 and
the carriage 15 is called the carriage assembly. The carriage 15 is
disposed over the main surface 11a of the main frame 11 with a
space left therebetween. The carriage 15 supports the magnetic
heads movably along a predetermined radial direction (i.e. a
direction indicated by an arrow B in FIG. 1) with respect to the
large-capacity FD 40.
76. The carriage 15 is supported and guided at both lower sides
thereof by a pair of guide bars 16 which extend to directions in
parallel with the predetermined radial direction B. The carriage
assembly is driven in the predetermined radial direction B by a
voice coil motor (VCM) which will later be described. As shown in
FIG. 1, the carriage assembly is provided with a pair of voice
coils 17 at opposite rear sides thereof. The voice coils 17 act as
components of the voice coil motor.
77. Now, description will be made as regards the voice coil motor
(VCM). The voice coil motor comprises the pair of voice coils 17
located at opposite rear side of the carriage assembly and wound
around drive axes parallel to the predetermined radial direction B,
and a pair of magnetic circuits 20 for producing magnetic fields
intersecting electric currents flowing through the voice coils 17.
In the voice coil motor of the above-mentioned structure, when the
electric current is made to flow through each of the voice coils 17
in a direction intersecting the magnetic field produced by the
magnetic circuit 20, a drive force is generated in an extending
direction of each drive axis as a result of an interaction between
the electric current and the magnetic field. The drive force causes
the voice coil motor to make the carriage assembly move in the
predetermined radial direction B.
78. Turning back to FIGS. 3A and 3B again. the shell 42 has a first
notch 42c formed on a forward side thereof in the insertion
direction A. The shell 42 further has a second notch 42e formed on
a lateral side provided with a chamfered portion 42d for preventing
reverse insertion (wrong insertion in a vertical direction or in
the insertion direction A). The second notch 42e has a particular
shape and is formed at a particular position so that the second
notch 42e is engaged by a reverse insertion preventing lever of the
small-density exclusive type FDD. In other words, the shell of the
small-capacity FD does not have the first and the second notches
42c and 42e.
79. In addition, the magnetic recording medium 41 of the
large-capacity FD 40 has a medium rotation speed of 3,600 rpm. In
this connection, the magnetic recording medium of the
small-capacity FD has a medium rotation speed of 300 rpm. That is,
the medium rotation speed of the large-capacity FD 40 it twelve
times as large as that of the small-capacity FD.
80. Turning to FIG. 5, description will proceed to a motor drive 60
according to an embodiment of this invention. FIG. 5 shows the
motor drive 60 as well as the switch unit 50 illustrated in FIG. 1.
The motor drive 60 is for controlling drive of the spindle motor
100. The motor drive 60 comprises a logic circuit 61, a clock
oscillator 62, and a spindle motor driver 63. Responsive to a
detected signal from the switch unit 50, the logic circuit 61
selectively produces one of a low speed selection signal S.sub.L
and a high speed selection signal S.sub.H in the manner which will
later become clear. The clock oscillator 62 oscillates a clock
signal CLK having a clock frequency of 1 MHz. Responsive either the
low speed selection signal S.sub.L or the high speed selection
signal S.sub.H, the spindle motor driver 63 drives the spindle
motor 100 in synchronism with the clock signal CLK on the basis of
the FG signal.
81. The low speed selection signal S.sub.L is a signal indicative
of making the magnetic recording medium of the loaded FD rotate at
the low rotation speed of 300 rpm. The high speed selection signal
S.sub.H is a signal indicative of making the magnetic recording
medium of the loaded FD rotate at the high rotation speed of 3,600
rpm.
82. The spindle motor driver 63 comprises a phase-locked loop (PLL)
circuit 631, a driving transistor 632, and a mode selection circuit
633. The PLL circuit 631 includes a frequency divider (not shown)
for frequency dividing the clock signal CLK. Responsive to the low
speed selection signal S.sub.L, the frequency divider frequency
divides the clock signal CLK having the clock frequency of 1 MHz
into a divided signal signal having a divided frequency of 300 Hz.
Likewise, responsive to the high speed selection signal S.sup.H,
the frequency divider frequency divides the clock signal having the
clock frequency of 1 MHz into a divided signal having a divided
frequency of 3,600 Hz. The PLL circuit 631 detects a phase
difference between the FG signal and the divided signal to produce
a control signal indicative of the phase difference.
83. The three-phase coils 124 have a common connection terminal
124a which is connected to a ground terminal via a speed switching
device 134. Responsive to the low speed selection signal S.sub.L,
the mode selection circuit 633 turns the speed switching device 134
off to make the three-phase coils 124 the bipolar connection and to
supply the driving transistor 632 with a mode selection signal
indicative of a low speed rotation mode. On the other hand,
responsive to the high speed selection signal S.sub.H, the mode
selection circuit 633 turns the speed switching device 134 on to
make the three-phase coils 124 the unipolar connection and to
supply the driving transistor 632 with the mode selection signal
indicative of a low speed rotation mode. On the basis of the
control signal and the mode selection signal, the driving
transistor 632 drives the spindle motor 100. That is, the spindle
motor driver 63 drives the spindle motor 100 so that the frequency
of the FG signal coincides with the divided frequency of the
divided signal.
84. Although the speed switching device 134 is connected to the
ground terminal in the example being illustrated, the speed
switching device 134 may be connected to a power supply terminal
(not shown).
85. FIG. 6 shows basic torque characteristic curves of the spindle
motor 100 in a case of making the connection of the three-phase
coils 124 of the spindle motor 100 the unipolar connection and the
bipolar connection. In FIG. 6, the abscissa and the ordinate
represent the torque (g-cm) and the number of revolution (rpm). In
FIG. 6, a symbol of T.sub.U represents a basic torque
characteristic curve of the spindle motor 100 in a case of the
unipolar connection while another symbol of T.sub.B represents
another basic torque characteristic curve of the spindle motor 100
in another case of the bipolar connection. As mentioned in the
preamble of the instant specification, in the
high-density/low-density compatible type FDD, it is necessary to
have the torque equal to or more than 14 g-cm at the high rotation
speed mode indicative of the number of revolution of 3,600 rpm and
to have the torque equal to or more than 60 g-cm at the low
rotation speed mode indicative of the number of revolution of 300
rpm. As illustrated in FIG. 6, the torque is equal to about 25 g-cm
on the number of revolution of 3,600 rpm in the case of the
unipolar connection while the torque is equal to about 65 g-cm on
the number of revolution of 300 rpm in the case of the bipolar
connection. As a result, it is understood that it is possible to
obtain a necessary torque by making the connection of the
three-phase coils 124 of the spindle motor 100 the unipolar
connection and the bipolar connection on the high rotation speed
mode and the low rotation speed mode, respectively.
86. However, it is difficult to control the number of revolution of
the spindle motor 100 in a stable and at a high precision only when
the connection of the three-phase coils of the spindle motor 100 is
switched although the necessary torque maybe obtained. Accordingly,
the motor drive 60 according to this invention controls the number
of revolution of the spindle motor 100 in each rotation speed mode
in stable and at the high precision by detecting the number of
revolution of the spindle motor 100 by the FG pattern 132 and by
using feedback control. In other words, it is possible for the
high-density/low-density compatible type FDD to restrain
fluctuations in the number of revolution of the spindle motor 100
in each rotation speed mode with 0.2%.
87. Referring to FIGS. 1 through 5, the description will proceed to
operation of the high-density/low-density compatible type FDD
provided with the motor drive 60 illustrated in FIG. 5.
88. Description will at first proceed to operation of the
high-density/low-density compatible type FDD illustrated in FIG. 1
in a case of rotatably driving the magnetic recording medium 41 of
the large-capacity FD 40 (FIGS. 3A and 3B) with the large-capacity
FD 40 loaded in the high-density/low-density compatible type FDD.
When the large-capacity FD 40 is loaded in the
high-density/low-density compatible type FDD, the top end 71a of
the eject lever 71 ie engaged the upper end 47b of the right side
edge of the shutter 47. With the movement of the large-capacity FD
40, the laver unit 70 is rotated in the clockwise direction.
Consequently, the shutter 47 is forced by the top end 71a of the
eject lever 71 to make sliding movement in the direction depicted
by the arrow E.
89. Subsequently, the disk holder unit holding the large-capacity
FD 40 descends and then the large-capacity FD 40 is loaded with a
load downwards. As a result, the disk hub 43 of the large-capacity
FD 40 is mechanically in contact with the disk holder table 12 with
the spindle shaft 104 of the spindle motor 100 freely received in
the disk center hole 43a bored in the disk hub 43 of the
large-capacity FD 40 and then the magnetic recording medium 41 of
the large-capacity FD 40 is put between the pair of the magnetic
heads. At the same time, the switch unit 50 detects that the loaded
FD is the large-capacity FD 40 and then supplies the logic circuit
61 with the detected signal indicative of detection of the
large-capacity FD 40.
90. Responsive to the detected signal, the logic circuit 61
determines that the loaded FD is the large-capacity FD 40 and then
delivers the high speed selection signal S.sub.H to the the
phase-locked loop circuit 631 and the mode selection circuit 633.
Responsive to the high speed selection signal S.sub.H, the mode
selection circuit 633 turns the speed switching device 134 on to
make the connection of the three-phase coils 124 the unipoler
connection and to supply the driving transistor 632 with the mode
selection signal indicative of the high speed rotation mode. As a
result, a combination of the phase-locked loop circuit 631 and the
driving transistor 632 in the spindle motor driver 63 drives the
spindle motor 100 so as to rotate at the high rotation speed of
3,600 rpm.
91. Description will proceed to operation of the
high-density/low-density compatible type FDD illustrated in FIG. 1
in another case of rotatably driving the magnetic recording medium
of the small-capacity FD with the small-capacity FD loaded in the
high-density/low-density compatible type FDD. In this event, the
switch unit 50 detects that the loaded FD is the small-capacity FD
and then supplies the logic circuit 61 with the detected signal
indicative of detection of the small-capacity FD.
92. Responsive to the detected signal, the logic circuit 61
determines that the loaded FD is the small-capacity FD and then
delivers the low speed selection signal S.sub.L to the the
phase-locked loop circuit 631 and the mode selection circuit 633.
Responsive to the low speed selection signal S.sub.L, the mode
selection circuit 633 turns the speed switching device 134 off to
make the connection of the three-phase coils 124 the bipoler
connection and to supply the driving transistor 632 with the mode
selection signal indicative of the low speed rotation mode. As a
result, the combination of the phase-locked loop circuit 631 and
the driving transistor 632 in the spindle motor driver 63 drives
the spindle motor 100 so as to rotate at the low rotation speed of
300 rpm or 360 rpm.
93. Although switching of the rotation speed in the spindle motor
100 is carried out by switching a dividing number in the PLL
circuit 631 in the example being illustrated, the switching of the
rotation speed in the spindle motor 100 may be carried out by
switching of clock frequencies of the clock oscillator 62. In
addition, the spindle motor driver 63 may comprise two PLL
circuits, namely, a first PLL circuit for the low rotation speed
and a second PLL circuit for the high rotation speed and may select
one of the two PLL circuits by switching from one to another.
94. Referring to FIG. 7, description will proceed to another
high-density type FDD to which this invention is applicable. The
illustrated high-density type FDD is similar in structure to that
illustrated in FIG. 1 except that the switch unit is modified to
different from that described in conjunction with FIG. 1 as will
later become clear. The switch unit is therefore depicted at 50A.
The switch unit 50A comprises, as the push switches, the write
control switch 51 and the large-capacity detecting switch 52 alone.
In other words, the type detecting switch 53 is omitted from the
switch unit 50 illustrated in FIG. 1.
95. Turning to FIGS. 8A and 8B, description will proceed to another
large-capacity FD 40A which is loaded in the high-density type FDD
illustrated FIG. 7. The illustrated large-capacity FD 40A is
similar in structure to that illustrated in FIGS. 3A and 3B except
that the type identifier hole 46 is omitted from the large-capacity
FD 40 illustrated in FIGS. 3A and 3B.
96. Turning to FIG. 9, description will proceed to a magnetic
recording medium received in the shell 42 of the large-capacity FD
40A. The magnetic recording medium for the large-capacity FD 40A is
modified to different from the magnetic recording medium 41 for the
large-capacity FD 40 as will later become clear. The magnetic
recording medium is therefore depicted at 41A.
97. The magnetic recording medium 41A comprises a plurality of
tracks 411 thereon which are arranged with concentric circles
around a center of rotation thereof. The tracks 411 may be arranged
with a spiral fashion around the center of rotation thereof. Each
track 411 is divided in a circumferential direction into a
predetermined number of sectors 412 having a length equal to one
another. It is assumed that the large-capacity FD 40A has the
storage capacity of 128 Mbytes. In this event, the large-capacity
FD 40A or the magnetic recording medium 41A comprises the tracks
411 which are equal in total number and in available total number
to 1,866 and 1,564 each side, respectively. Each track 411 is
divided into the sectors 412 which are equal in number to 80. The
large-capacity FD 40A has a medium storage capacity of about 160
Mbytes in all both sides and has a format storage capacity of about
128 Mbyte in all both sides. That is, a physical formatting for the
magnetic recording medium 41A arranges the tracks 411 thereon with
concentric circles that equal in number to 1,564 on one side and
divides each track 411 into the sectors 412 which are equal in
number to 80. Each sector 412 consists of a servo field (not shown)
and a data field (not shown).
98. In addition, the magnetic recording medium 41A has a medium
rotation speed of 3,600 rpm. I this connection, the a magnetic
recording medium of the small-capacity FD has a medium rotation
speed of 300 or 360 rpm. That is, the medium rotation speed of the
large-capacity FD 40A is twelve or ten times as large as that of
the small-capacity FD.
99. As shown in FIG. 9, the tracks 411 on the magnetic recording
medium 41A are separated into a user data area 413 available to a
user and an alternate area 414 other than the user data area 413.
The alternate area 413 is disposed in the magnetic recording medium
41A in a radial direction inward as shown in FIG. 9. The alternate
area 414 may be disposed in the magnetic recording medium 41A in
the radial direction outward.
100. The alternate area 414 of the magnetic recording medium 41A is
provided not only with a predetermined sector 414a for storing a
defective map (which will later become clear) but also with an
information identification sector 414b for storing capacity
information indicative of the storage capacity of the magnetic
recording medium 41A. In this connection, an alternate area of the
magnetic recording medium 41 for the large-capacity FD 40
illustrated in FIGS. 3A and 3B is provided only with the
predetermined sector 414a for storing the defective map.
101. It is presumed that the large-capacity FD 40A is loaded in the
high-density type FDD illustrated in FIG. 8. In this event, the
high-density type FDD can detect, in response to a detection signal
from the switch unit 50A, that the loaded FD is the large-capacity
FD 40A. Thereafter, the high-density type FDD can detect the type
of the loaded large-capacity FD 40A, namely, the storage capacity
of the loaded large-capacity FD 40A by reading the capacity
information out of the information identification sector 414b by
the magnetic head thereof.
102. It is assumed that the high-density type FDD illustrated in
FIG. 7 is the double-density large-capacity FDD and the loaded
large-capacity FD 40A is the single-density large-capacity FD.
Under the circumstances, the double-density large-capacity FDD can
control so as to carry out reproduction of the single-density
large-capacity FD alone by detecting the storage capacity of the
loaded large-capacity FD 40A in the manner which is described
above.
103. Although the predetermined sector 414a and the information
identification sector 414b are apart from each other in the
above-mentioned embodiment, both of the defective map and the
capacity information may be stored in the same sector. In other
words, the information identification sector 414b may share the
predetermined sector 414a. That is, the predetermined sector 414a
may serve as the information identification sector 414b also.
104. In the example being illustrated, it is assumed that there is
defective sectors depicted at x1, x2, . . . and so on as shown in
FIG. 9. In this event, a media formatter (not shown) performs test
of sector format to detects the detective sectors on on the user
data area 413 and carries out rearrangement of the sectors 412
except for the defective sectors. In the example being illustrated,
the media formatter carries out rearrangement of the sectors ST so
that the defective sectors x1 and x2 are alternated by alternate
sectors depicted at 01 and 02 in the alternate area 414,
respectively. Thereafter, the media formatter prepares the
defective map which is a table for entering information indicating
where the defective sectors on the user data area 413 are arranged
to which alternate sectors in the alternate area 414. The defective
map is stored in the predetermined sector 414b in the alternate
area 414. If the storage capacity of the magnetic recording medium
41A formatted is less than a predetermined specification storage
capacity due to the presence of a lot of defective sectors, the
formatted magnetic recording medium 41A is discarded because the
formatted magnetic recording medium 41A cannot be used. Finally,
the media formatter writes the capacity information indicative of
the storage capacity of the magnetic recording medium 41A in the
information identification sector 414b in the alternate area
414.
105. Turning to FIG. 10, description will proceed to a signal
system 150 for use in the high-density/low-density compatible type
FDD illustrated in FIG. 7. As shown in FIG. 10, the
high-density/low-density compatible type FDD is provided with, as
the magnetic heads depicted at 13, an upper low-density magnetic
head MH.sub.F1, an upper high-density magnetic head MH.sub.H1, a
lower low-density magnetic head MH.sub.F0, and a lower high-density
magnetic head MH.sub.H0. Those magnetic heads MH.sub.F1, MH.sub.F0,
MH.sub.H1, and MH.sub.H0 are supported by the carriage 15 (FIG.
7).
106. In a case when data recording/reproducing is carried out with
respect to the magnetic disk medium of the small-capacity FD
depicted at 40', low-density write-in data WD.sub.F is supplied
from a small-capacity FD controller (FDC) 200 and low-density
read-out data RD.sub.F is delivered to the small-capacity FD
controller 200. On the other hand, in a case when data
recording/reproducing is carried out with respect to the magnetic
disk medium 41A (FIG. 9) of the large-capacity FD 40A (FIGS. 8A and
8B), high-density write-in data WD.sub.H is supplied from a host
system (not shown) and high-density read-out data RD.sub.H is
delivered to the host system.
107. The illustrated signal system 150 for the
high-density/low-density compatible type FDD comprises a
recording/reproducing head amplifier 152, a small-capacity FD
reproducing circuit 154, a large-capacity FD recording/reproducing
circuit 156, a small-capacity FD interface (FD I/F) 158, a logic
circuit 160, a large-capacity FD controller and interface (HDC I/F)
162, and a digital signal processor (DSP) 164. The logic circuit
160 includes a data selector 160a.
108. The recording/reproducing head amplifier 152 is mounted on the
carriage 15 (FIG. 7) for supporting the low-density magnetic heads
MH.sub.F1 and MH.sub.F0 and the high-density magnetic heads
MH.sub.H1 and MH.sub.H0. The recording/reproducing head amplifier
152 amplifies data read by the low-density magnetic heads MH.sub.F1
and MH.sub.F0 and the high-density magnetic heads MH.sub.H1 and
MH.sub.H0 to produce low-density read amplified data and
high-density read amplified data, respectively. In addition, the
recording/reproducing head amplifier 152 supplies writing amplified
data to the low-density magnetic heads MH.sub.F1 and MH.sub.F0 and
the high-density magnetic heads MH.sub.H1 and MH.sub.H0.
109. The small-capacity flexible disk reproducing circuit 154 and
the large-capacity flexible disk recording/reproducing circuit 156
are mounted on the printed-circuit board 22 (FIG. 7) and are
connected to the recording/reproducing head amplifier 152. The
small-capacity FD reproducing circuit 154 serves as a low-density
reproducing circuit for reproducing the low-density read amplified
data in accordance with an MFM (modified frequency modulation)
modulation/demodulation system. The large-capacity FD
recording/reproducing circuit 156 acts as a high-density
reproducing circuit for reproducing the high-density read amplified
data in accordance with a 1-7 RLL (run length limited code)
modulation/demodulation system. In addition, the large-capacity FD
recording/reproducing circuit 156 modulates the high-density
write-in data WD.sub.H from the large-capacity FD controller and
interface 162 in accordance with the 1-7 RLL
modulation/demodulation system to deliver modulated data to the
data selector 160a.
110. Reproduced by the small-capacity FD disk reproducing circuit
154, data is delivered as the low-density write-in data WD.sub.F to
the small-capacity FD controller 200 through the small-capacity FD
interface 158. On the other hand, supplied from the small-capacity
FD controller 200, the low-density write-in data WD.sub.F is
delivered to the recording/reproducing head amplifier 152 through
the data selector 160a.
111. Reproduced by the large-capacity FD recording/reproducing
circuit 156, data is delivered as the high-density read-out data
RD.sub.H to the host system through the large-capacity FD
controller and interface 162. On the other hand, supplied from the
host system, the high-density write-in data WD.sub.H is delivered
to the large-capacity FD recording/reproducing circuit 156 through
the large-capacity FD controller and interface 162, modulated by
the large-capacity FD recording/repro-ducing circuit 156 in
accordance with the 1-7 RLL modulation/demodulation system, and
thereafter delivered to the recording/reproducing head amplifier
152 through the data selector 160a.
112. The data selector 160a in the logic circuit 160 is supplied
from the switch unit 50A with an identification detected signal DD
indicating whether the FD loaded in the high-density/low-density
compatible type FDD is the large-capacity FD 40A or the
small-capacity FD 40'. When the identification detected signal DD
indicates detection of the small-capacity FD 40', the data selector
160a selects the low-density write-in data WD.sub.F from the
low-capacity flexible disk controller 200 to deliver it to the
recording/reproducing head amplifier 152. On the other hand, when
the identification detected signal DD indicates detection of the
large-capacity FD 40A, the data selector 160a selects the modulated
data from the large-capacity FD recording/reproducing circuit 156
to deliver it to the recording/reproducing head amplifier 152.
113. Responsive to the identification detected signal DD, the logic
circuit 160 delivers first and second head selection signals HS1
and HS0 to the recording/reproducing head amplifier 152. The first
head selection signal HS1 is a signal indicative of selecting
either the upper magnetic heads MH.sub.H1 and MH.sub.F1 or the
lower magnetic heads MH.sub.H0 and MH.sub.F0. The first head
selection signal HS1 indicates selection of the upper magnetic
heads MH.sub.H1 and MH.sub.F1 when the first head selection signal
HS1 takes a logic "0" level. When the first head selection signal
HS1 takes a logic "1" level, the first head selection signal HS1
indicates selection of the lower magnetic heads MH.sub.H0 and
MH.sub.F0. On the other hand, the second head selection signal HS0
is a signal indicative of selecting either the low-density magnetic
heads MH.sub.F1 and MH.sub.F0 or the high-density magnetic heads
MH.sub.H1 and MH.sub.H0. The second selection signal HS0 takes the
logic "0" level to indicate selection of the high-density magnetic
heads MH.sub.H1 and MH.sub.H0 when the identification detected
signal DD indicates detection of the large-capacity FD 40A. When
the identification detected signal DD indicates detection of the
small-capacity FD 40', the second selection signal HS0 takes the
logic "1" level to indicate selection of the low-density magnetic
heads MH.sub.F1 and MH.sub.F0.
114. It is assumed that the identification detected signal DD
indicates detection of the large-capacity FD 40A. In this event,
the high-density magnetic heads MH.sub.H1 and MH.sub.H0 read the
capacity information out of the information identification sector
414b on the magnetic recording medium 41A of the large-capacity FD
40A. The readout capacity information is amplified by the
recording/reproducing head amplifier 152, reproduced by the
large-capacity FD recording/reproducing circuit 156, and delivered
to the large-capacity FD controller and interface 162. It is
possible for the large-capacity FD controller and interface 162 to
recognize the storage capacity of the large-capacity FD 40A on the
basis of the delivered capacity information. As a result, it is
possible for the high-density/low-density compatible type FDD
illustrated in FIG. 7 to carry out control so as to match with the
storage capacity of the large-capacity FD 40A loaded therein. At
any rate, a combination of the magnetic heads 13 (the high-density
magnetic heads MH.sub.H1 and MH.sub.H0), the recording/reproducing
head amplifier 152, the large-capacity FD recording/reproducing
circuit 156, and the large-capacity FD controller and interface 162
serves as an arrangement for reading the capacity information out
of a specific sector or the information identification sector 414b
on the magnetic recording medium 41A of the large-capacity FD 40A
and for recognizing the storage capacity of the large-capacity FD
40A on the basis of the readout capacity information.
115. In addition, the large-capacity FD controller and interface
162 is controlled by the digital signal processor 164.
116. While this invention has thus far been described in
conjunction with a few preferred embodiments thereof, it will now
be readily possible for those skilled in the art to put this
invention into various other manner. For example, this invention
may be applicable to other removable type magnetic
recording/reproducing devices although the above-mentioned
embodiments are applied to the high-density type FDDs.
* * * * *