U.S. patent application number 09/132252 was filed with the patent office on 2001-08-09 for recording disk with round spindle hole in magnetic hub and prerecordedtracking servo information.
Invention is credited to OOSATO, MAMORU, SUZUKI, HIROYUKI, TOMITA, YASUSHI.
Application Number | 20010012180 09/132252 |
Document ID | / |
Family ID | 16752078 |
Filed Date | 2001-08-09 |
United States Patent
Application |
20010012180 |
Kind Code |
A1 |
TOMITA, YASUSHI ; et
al. |
August 9, 2001 |
RECORDING DISK WITH ROUND SPINDLE HOLE IN MAGNETIC HUB AND
PRERECORDEDTRACKING SERVO INFORMATION
Abstract
A disc includes a disc substrate having a major surface
operating as a signal recording portion and having a substantially
circular center opening in said major surface, and a hub mounted on
the disc substrate for closing the center opening in the disc
substrate. The hub includes an inner rim portion having the spindle
opening at its center and an outer rim portion connected to an
outer side of the inner rim portion for extending from the inner
rim portion via a step difference towards the side of insertion in
the spindle opening. When the hub is set on the disc table, the
outer rim portion protruded on the side from which the spindle is
inserted into said spindle opening with a step difference
approaches to a magnet provided on the disc table to increase the
force of suction by the magnet so that the magnetic disc is chucked
with respect to the disc table solely by the force of suction by
the magnet.
Inventors: |
TOMITA, YASUSHI; (KANAGAWA,
JP) ; OOSATO, MAMORU; (TOKYO, JP) ; SUZUKI,
HIROYUKI; (KANAGAWA, JP) |
Correspondence
Address: |
JAY H MAIOLI
COOPER AND DUNHAM
1185 AVENUE OF THE AMERICAS
NEW YORK
NY
10036
|
Family ID: |
16752078 |
Appl. No.: |
09/132252 |
Filed: |
August 11, 1998 |
Current U.S.
Class: |
360/133 ;
G9B/17.006; G9B/23.005 |
Current CPC
Class: |
G11B 23/0035 20130101;
G11B 17/0282 20130101 |
Class at
Publication: |
360/133 |
International
Class: |
G11B 023/03 |
Foreign Application Data
Date |
Code |
Application Number |
Aug 15, 1997 |
JP |
P09-220504 |
Claims
What is claimed is:
1. A disc-shaped recording medium comprising: a disc substrate
having a major surface operating as a signal recording portion and
having a substantially circular center opening in said major
surface; and a hub mounted on the disc substrate for closing the
center opening in said disc substrate; said hub having a circular
center spindle opening in which a spindle of a disc drive device is
inserted, said hub also having, at a predetermined distance from
the spindle opening, a driving member inserting opening in which a
driving member of the disc drive device is inserted.
2. The disc-shaped recording medium according to claim 1 wherein
said hub is of a magnetic material.
3. The disc-shaped recording medium according to claim 1 wherein
servo information for tracking servo is pre-recorded in said signal
recording portion.
4. The disc-shaped recording medium according to claim 1 wherein
said hub includes an inner rim portion having said spindle opening
at its center and an outer rim portion connected to an outer side
of the inner rim portion for extending from said inner rim portion
via a step difference towards a side from which said spindle is
inserted into said spindle opening.
5. The disc-shaped recording medium according to claim 1 wherein
the information is magnetically recorded on said signal recording
portion.
6. A disc cartridge comprising: a main cartridge body portion made
up of a pair of halves, with an opening being formed in one of the
halves for insertion of a spindle of a disc drive device therein;
and a disc-shaped recording medium rotatably housed in said main
cartridge body portion; said disc-shaped recording medium having a
disc substrate having a major surface operating as a signal
recording portion and a substantially circular center opening in
said major surface and a hub mounted on said disc substrate for
closing said center opening provided in said disc substrate; said
hub having a circular center spindle opening in which said spindle
is inserted, said hub also having, at a predetermined distance from
the spindle opening, a driving member inserting opening in which a
driving member of the disc drive device is inserted.
7. The disc cartridge according to claim 6 wherein said hub is of a
magnetic material.
8. The disc cartridge according to claim 6 wherein servo
information for tracking servo is pre-recorded in said signal
recording portion.
9. The disc cartridge according to claim 6 wherein said hub
includes an inner rim portion having said spindle opening at its
center and an outer rim portion connected to an outer side of the
inner rim portion via a step difference for extending from said
inner rim portion towards a side from which said spindle is
inserted into said spindle opening.
10. The disc cartridge according to claim 6 wherein the information
is magnetically recorded on said signal recording portion.
11. A disc-shaped recording medium comprising: a disc substrate
having a major surface operating as a signal recording portion and
having a substantially circular center opening in said major
surface; and a hub mounted on the disc substrate for closing the
center opening in said disc substrate; said hub including an inner
rim portion having a spindle opening at its center and an outer rim
portion connected to an outer side of the inner rim portion via a
step difference for extending from said inner rim portion towards a
side from which said spindle is inserted into said spindle
opening.
12. The disc-shaped recording medium according to claim 11 wherein
said hub is of a magnetic material.
13. The disc-shaped recording medium according to claim 11 wherein
servo information for tracking servo is pre-recorded in said signal
recording portion.
14. The disc-shaped recording medium according to claim 11 wherein
the information is magnetically recorded on said signal recording
portion.
15. A disc cartridge comprising: a main cartridge body portion made
up of a pair of halves, with an opening being formed in one of the
halves for insertion of a spindle of a disc drive therein; and a
disc-shaped recording medium rotatably housed in said main
cartridge body portion; said disc-shaped recording medium including
a disc substrate having a major surface operating as a signal
recording portion and having a substantially circular center
opening in said major surface; and a hub mounted on the disc
substrate for closing the center opening in said disc substrate;
said hub including an inner rim portion having a center spindle
opening into which said spindle is inserted and an outer rim
portion connected to an outer side of the inner rim portion via a
step difference for extending from said inner rim portion towards a
side from which said spindle is inserted into said spindle
opening.
16. The disc cartridge according to claim 15 wherein said hub is of
a magnetic material.
17. The disc cartridge according to claim 15 wherein servo
information for tracking servo is pre-recorded in said signal
recording portion.
18. The disc-shaped recording medium according to claim 15 wherein
the information is magnetically recorded on said signal recording
portion.
Description
BACKGROUND OF THE INVENTION
[0001] 1. Field of the invention
[0002] This invention relates to a signal recording medium and a
disc cartridge holding this signal recording medium.
[0003] 2.Description of related Art
[0004] Up to now, a signal recording medium, having the major
surface of a flexible disc substrate as a signal recording surface
and adapted for recording information signals on this signal
recording surface, such as a magnetic disc, has been in use.
[0005] As a magnetic disc employing a flexible disc substrate, such
a disc having the diameter of 3.5 inch is in use. This magnetic
disc has a center hub for chucking the magnetic disc to a disc
drive device. The magnetic disc, used so fat extensively, has a
recording capacity of 2 megabyte (MB).
[0006] The magnetic disc 200, now in wise use, has a disc substrate
201 of a flexible synthetic resin material, with the major surface
of the disc substrate being used as a signal recording surface, as
shown in FIGS. 1 and 2. The disc substrate 201 has a circular
center opening 201 a which is closed by a hub 202.
[0007] This hub 202 is formed of a magnetic material, such as iron,
and has a tubular projection 202a fitted in the center opening
201a, and is mounted on the disc substrate 201 by having a flange
202b on the outer rim side of the projection 202a bonded to the rim
of the center opening center opening center opening 201a, as shown
in FIG. 2. At the center of the hub 202 is formed a rectangular
spindle opening 202b passed through by a spindle 221 of a rotation
driving unit 220 provided on the disc drive device as shown in FIG.
3. At a position of the hub 202 offset from a driving pin 223 on
the disc drive device is bored a rectangular driving pin engagement
opening 202c engaged by a driving pin 223 on the disc drive device.
That is, the driving pin engagement opening 202c is formed at a
pre-set distance from the spindle opening 202b.
[0008] The spindle opening 202b, provided in the hub 202,
substantially has the shape of a square each side being sized to be
slightly larger than the diameter of the spindle passed therein.
This spindle opening 202b has its center C1-C1 offset towards the
driving pin engagement opening 202c with respect to the center
02-02 of the hub 202, as shown in FIG. 2. The spindle opening 202b
is formed in the course of drawing the magnetic material of the hub
202 and has an upstanding wall section 202f on each side, as shown
in FIG. 2. These upstanding wall sections 202f support the
peripheral surface of the spindle 221 passed through the spindle
opening 202b and functions to permit the spindle 221 to pass
through the spindle opening 202b. The corners of the substantially
square-shaped spindle opening 202b are arcuately formed, as shown
in FIG. 1.
[0009] The hub 202, mounted on the disc substrate 201, has the
distal end face of the projection projection 202a, in which are
formed the spindle opening 202b and the driving pin engagement
opening 202c, as a setting surface 202e for a disc supporting
surface 222a of a disc table 222 of the disc rotation unit 220. The
outer rim side of the setting surface 202e is used as a suction
portion by a magnet 224 arranged on the outer rim side of the disc
supporting surface 222a.
[0010] The magnetic disc 200, arranged as described above, is
rotated in unison with the disc table 222 of the disc rotation unit
220 provided on the disc drive device side, as the hub 202 is
checked and centered with respect to the disc table 222. The
information signals are recorded or reproduced for the magnetic
disc 200 by the magnetic disc 200 being operated by a magnetic
head.
[0011] The disc rotation unit 220, provided on the disc drive
device, on which is loaded the magnetic disc 200, has the disc
table 222 integrally mounted on the distal end of the spindle 221
run in rotation by a spindle motor, not shown, as shown in FIG. 3.
The upper surface of the disc table 222 mounted on the distal end
of the spindle spindle 221 is a disc supporting surface 222a on
which is set the hub 202 of the magnetic disc 200. On the disc
table 222 is mounted a driving pin 223 at a position offset from
the spindle 221. The driving pin 223 is mounted for movement in a
direction emerging from or receding into the disc supporting
surface 222a and in a direction towards and away from the disc
supporting surface 222a. The driving pin 223 is biased by biasing
means, not shown, in a direction away from the spindle 221.
[0012] On the disc supporting surface 222a of the disc table 222 is
arranged a ring-shaped magnet 224, such as a rubber magnet,
arranged for surrounding the disc supporting surface 222a. The
magnet 224 is mounted on the disc table 222 so that the magnet is
lower in level than the disc supporting surface 222a on which is
set the hub 202 of the magnetic disc 200 so that a pre-set distance
H0 is maintained between the magnet surface and the setting surface
202e of the hub 202 set on the disc supporting surface 222a.
[0013] The magnetic disc 200 is chucked on the disc table 222 by
having the spindle 221 passed through the spindle opening 202b,
engaging the driving pin 223 in the driving pin engagement opening
202c, setting the setting surface 202e on the disc supporting
surface 222a of the disc table 222, as shown in FIG. 4 and by
having the hub 202 sucked by the magnet 224.
[0014] The state in which the magnetic disc 200 is loaded on the
disc table 222 is hereinafter explained.
[0015] In an initial state in which the magnetic disc 200 is set on
the disc table 222 and the spindle 221 is passed through the
spindle opening 202b with the driving pin 223 engaging in the
driving pin engagement opening 202c, the spindle 221 and the
driving pin 223 are usually inserted into or engaged with the
spindle opening 202b and the driving pin engagement opening 202c
without being thrust from the inner peripheral surface of the
spindle opening 202b or the driving pin engagement opening 202c. At
this time, the center-to-center distance F between the spindle 221
and the driving pin 223 is an initial state distance for which the
driving pin 223 is not moved towards the outer rim of the magnetic
disc 200.
[0016] The spindle opening 202b is formed as a square-shaped
opening having the length of each side equal to L and having
arcuately rounded corners, as shown in FIG. 5. The spindle 221,
inserted into the spindle opening 202b, is formed as a column
having a diameter .phi.E shorter than the length D of one each side
of the spindle opening 202b. The driving pin engagement opening
202c is formed as a rectangle having a length of a long side and a
length of a short side equal to A and B, respectively, and
arcuately rounded corners, as shown in FIG. 5. The driving pin 223,
engaged in this driving pin engagement opening 202c, is formed as a
column having a diameter .phi.C shorter than the a length B of the
short side of the driving pin engagement opening 202c.
[0017] If the disc table 222 is run in rotation in the direction
indicated by arrow R in FIG. 5, from an initial state in which
magnetic disc 200 is set on the disc table 222, with the spindle
221 passed through the spindle opening 202b and with the driving
pin 223 engaged in the driving pin engagement opening 202c, as
shown in FIG. 5, the driving pin 223 compresses against an outer
corner of the driving pin engagement opening 202c disposed in the
rotating direction of the disc table 222, as shown in FIG. 6, to
shift the magnetic disc 200 towards the outer rim of the spindle
221. By the magnetic disc 200 being moved towards the outer rim of
the spindle 221 by the driving pin 223, the spindle 221 is abutted
on the corner of the driving pin engagement opening 202c of the
spindle opening 202b remotest from the corner of the driving pin
engagement opening 202c on which is abutted the driving pin 223, as
shown in FIG. 6, thus centering the hub 202 of the magnetic disc
200 with respect to the disc table 222.
[0018] When the hub 202 of the magnetic disc 200 is centered with
respect to the disc table 222, there is produced a differential
rotational velocity between the disc table 222 and the magnetic
disc 200. That is, the driving pin 223 is rotated in advance of the
magnetic disc 200 so that the driving pin 223 is abutted against
the outer corner of the driving pin engagement opening 202c
disposed along the rotational direction of the disc table 222. By
the driving pin 223 compressing against the driving pin engagement
opening 202c, the magnetic disc 200 is moved from the center
towards the outer rim of the spindle 221 to center the hub 202 with
respect to the disc table 222. At this time, the driving pin 223 is
moved towards the inner rim of the hub 202 so that the
center-to-center distance G between the spindle 221 and the driving
pin 223 becomes smaller than the initial distance F shown in FIG.
5.
[0019] By the magnetic disc 200 being attracted to the disc table
222 by the magnet 224, the magnetic disc 200 is rotated in unison
with the disc table 222 in the centered state. By the magnetic head
scanning the signal recording area of the magnetic disc 200 in this
state, the information signals can be recorded or reproduced for
the magnetic disc 200.
[0020] The magnetic disc 200, arranged as described above, is
housed in a main cartridge body portion 213 to form a disc
cartridge 210, as shown in FIGS. 7 and 8. The magnetic disc 200 is
loaded on the disc drive device as the magnetic disc is held in the
main cartridge body portion 213 and chucked on the disc table 222
of the disc rotation unit 220.
[0021] The disc cartridge 210, holding the magnetic disc 200, is
provided with the main cartridge body portion 213, produced by
abutting and interconnecting an upper cartridge half and a lower
cartridge half, and the magnetic disc 200 is rotatably housed
within this main cartridge body portion 213. At a mid portion on
the lower surface of the main cartridge body portion 213 is formed
a spindle opening 215 into which is inserted the spindle 211, as
shown in FIG. 8. In the facing upper and lower surfaces of the main
cartridge body portion 213 are formed rectangular recording and/or
reproducing apertures 221, 222. These apertures 221, 222 are
disposed at a mid position in the left-and-right direction of the
main cartridge body portion 213, and are formed from the vicinity
of the spindle opening 215 towards the front side of the main
cartridge body portion 213. The magnetic disc 200 accommodated in
the main cartridge body portion 213 has its signal recording area
partially exposed vis the apertures 221, 222 across the inner and
outer rims of the disc. There is also provided in the main
cartridge body portion 213 a mistaken recording inhibiting hole 231
operating as a discriminating hole indicating whether or not the
information signals recorded on the magnetic disc 200 held therein
can be erased by overwriting or erasure. There is also provided in
the lower surface of the main cartridge body portion 213 in
register with the mistaken recording inhibiting hole 231 a disc
discriminating hole 232 specifying the sort of the magnetic disc
held in the main cartridge body portion 213, as shown in FIG. 8. By
detecting this disc discriminating hole 232, it can be
discriminated that the magnetic disc 200 held in the main cartridge
body portion 213 is of the recording capacity of 200 MB. The disc
discriminating hole 232 is provided in the disc cartridge 210
holding the magnetic disc 200 with the recording capacity of 2
MB.
[0022] On this disc cartridge 210 is mounted a shutter member 214,
formed by an metal plate of aluminum or stainless steel or molded
from a synthetic resin material, and which is adapted for
opening/closing the recording and/or reproducing apertures 221, 222
from the front side of the main cartridge body portion 213 while
being movable in a direction of opening/closing the recording
and/or reproducing apertures 221, 222. The shutter member 214 has
shutter portions 214a, 214b overlying the apertures 221, 222 and
having apertures 233, 234 registering with the apertures 221, 222
when the shutter member has moved to a position opening the
apertures 221, 222.
[0023] The magnetic disc with the diameter of 3.5 inch has a
recording capacity of 2 MB. For processing a program software or
data of a larger capacity, it is desired to furnish a magnetic disc
of a higher recording capacity.
[0024] On the other hand, the magnetic disc having the diameter of
3.5 inch is in widespread use as a recording medium for ain
information processing apparatus such as a computer. Thus, it is
desirable that the magnetic disc having the diameter of 3.5 inch
shall be usable with interchangeability on a disc drive device
having a magnetic disc of a high recording capacity.
[0025] The conventional magnetic disc, having the diameter of 3.5
inch, is run in rotation at 300 rpm for recording and/or
reproducing information signals, has a drawback that it is low in
the data transfer rate.
SUMMARY OF THE INVENTION
[0026] It is an object of the present invention to provide a
disc-shaped recording medium that can be used with
interchangeability with a conventional disc-shaped recording medium
on a common disc drive device, that enables constitution of a disc
drive device having a high data transfer rate and that can be
loaded in a stable state on a disc rotation unit. It is another
object of the present invention to provide a disc cartridge holding
this disc-shaped recording medium.
[0027] In one aspect, the present invention provides a disc-shaped
recording medium including a disc substrate having a major surface
operating as a signal recording portion and having a substantially
circular center opening in the major surface and a hub mounted on
the disc substrate for closing the center opening in the disc
substrate. The hub includes a circular center spindle opening in
which a spindle of a disc drive device is inserted. The hub also
includes, at a predetermined distance from the spindle opening, a
driving member inserting opening in which is inserted a driving
member of the disc drive device.
[0028] In another aspect, the present invention provides a disc
cartridge includes a main cartridge body portion made up of a pair
of halves, with an opening being formed in one of the halves for
insertion of a spindle of a disc drive device therein, and a
disc-shaped recording medium rotatably housed in the main cartridge
body portion.
[0029] In a further aspect, the present invention provides a
disc-shaped recording medium having a disc substrate having a major
surface operating as a signal recording portion and a substantially
circular center opening in the major surface and a hub mounted on
the disc substrate for closing the center opening provided in the
disc substrate. The hub includes a circular center spindle opening
in which the spindle is inserted. The hub also includes, at a
predetermined distance from the spindle opening, a driving member
inserting opening in which a driving member of the disc drive
device is inserted.
[0030] In yet another aspect, the present invention provides a disc
cartridge including a main cartridge body portion made up of a pair
of halves, with an opening being formed in one of the halves for
insertion of a spindle of a disc drive device. On this main
cartridge body portion is mounted a hub including an inner rim
portion having a spindle opening at its center and an outer rim
portion connected to an outer side of the inner rim portion via a
step difference for extending from the inner rim portion towards a
side from which the spindle is inserted into the spindle opening.
The disc-shaped recording medium is rotatably housed in the disc
cartridge.
[0031] With the disc-shaped recording medium and the disc cartridge
holding this disc-shaped recording medium, described above, the hub
chucked on the disc table of the disc rotation unit has a circular
spindle opening and a driving pin engagement opening, in which is
inserted the driving pin, so that the disc cartridge can be
interchangeably loaded on the disc drive device on which the
conventional disc-shaped recording medium is loaded in centered
state.
[0032] In particular, since the spindle opening provided in the hub
is circular in profile, the hub can be formed to high accuracy. The
disc-shaped recording medium can be chucked on the disc table in
position in a stable state. The information signals can be recorded
and/or reproduced without oscillations in the rotational plane even
on high-speed rotation.
[0033] Moreover, with the disc-shaped recording medium according to
the present invention and the disc cartridge housing this recording
medium, since the hub mounted centrally of the disc substrate of
the disc-shaped recording medium includes an inner rim portion
having the spindle opening at its center and an outer rim portion
connected to an outer side of the inner rim portion via a step
difference for extending from the inner rim portion towards the
side of insertion in the spindle opening. When the disc cartridge
is mounted on the disc rotation unit of the disc drive device, the
outer rim portion of the hub can be approached to the magnet
provided on the disc rotation unit so that the hub can be loaded
with a larger force of suction on the disc rotation unit thus
improving suction to the disc table of the conventional magnetic
disc loaded in centered state on the disc table. In addition, the
magnetic disc rotated at an elevated speed can be positively
unified to the disc table.
BRIEF DESCRIPTION OF THE DRAWINGS
[0034] FIG. 1 is a plan view showing a conventional magnetic
disc.
[0035] FIG. 2 is a cross-sectional view of the magnetic disc shown
in FIG. 1.
[0036] FIG. 3 is a perspective view showing a disc rotation unit on
which is loaded a conventional magnetic disc.
[0037] FIG. 4 is a side view showing the state in which the
conventional magnetic disc is loaded on the disc rotation unit.
[0038] FIG. 5 is a plan view showing an initial state in which the
conventional magnetic disc has been set on a disc table.
[0039] FIG. 6 is a plan view showing the state in which the
conventional magnetic disc has been centered and loaded on a disc
table.
[0040] FIG. 7 is a plan view showing a conventional disc
cartridge.
[0041] FIG. 8 is a bottom view showing a conventional disc
cartridge.
[0042] FIG. 9 is an exploded perspective view showing a disc drive
device on which are selectively loaded a magnetic disc of the
present invention and a conventional magnetic disc.
[0043] FIG. 10 is a plan view showing a first embodiment of a
magnetic disc according to the present invention.
[0044] FIG. 11 is a cross-sectional view of the magnetic disc of
the first embodiment.
[0045] FIG. 12 is a schematic plan view showing the recording
format of the magnetic disc according to the present invention.
[0046] FIG. 13 is a schematic view showing the recording state of
the servo information recorded on the magnetic disc according to
the present invention.
[0047] FIG. 14 is a plan view showing the state in which the hub of
the magnetic disc according to the present invention has been
loaded on a disc table of the disc rotation unit.
[0048] FIG. 15 is an exploded perspective view showing a disc
cartridge according to the present invention holding a magnetic
disc according to the present invention.
[0049] FIG. 16 is a plan view showing a disc cartridge according to
the present invention.
[0050] FIG. 17 is bottom view showing a disc cartridge according to
the present invention.
[0051] FIG. 18 is a block circuit diagram of a disc drive device on
which are selectively loaded a magnetic disc according to the
present invention and a conventional magnetic disc.
[0052] FIG. 19 is a plan view showing a second embodiment of the
magnetic disc according to the present invention.
[0053] FIG. 20 is a cross-sectional view of the magnetic disc of
the second embodiment.
[0054] FIG. 21 is an exploded perspective view showing a disc
cartridge according to the present invention holding the second
embodiment of the magnetic disc according to the present
invention.
[0055] FIG. 22 is a plan view of the disc cartridge shown in FIG.
21.
[0056] FIG. 23 is a bottom view of the disc cartridge shown in FIG.
23.
[0057] FIG. 24 is a perspective view showing the state of mounting
a magnetic disc of the second embodiment of the present invention
on the disc rotation unit.
[0058] FIG. 25 is a perspective view showing the state in which the
magnetic disc of the second embodiment of the present invention has
been loaded on the disc rotation unit.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0059] A disc-shaped recording medium and a disc cartridge holding
this disc-shaped recording medium, according to the present
invention, are hereinafter explained.
[0060] In the following description, the present invention is
applied to a magnetic disc having a flexible disc substrate.
[0061] Before proceeding to description of the magnetic disc
according to the present invention, a disc drive device, on which
is used the magnetic disc of the present invention, is
explained.
[0062] The present disc drive device is adapted for enabling
recording and/or reproduction of information signals for both the
conventional magnetic disc having the recording capacity of 2 MB
and the magnetic disc according to the present invention.
[0063] The present disc drive device 150 has a base 151
substantially in the form of a flat plate and a disc rotation unit
100 at a mid portion of the base 151 for rotationally driving the
magnetic disc, as shown in FIG. 9. The disc rotation unit 100 has a
spindle motor 111 having a spindle 103 as a driving shaft on the
distal end of which is integrally carried a disc table 101. The
disc rotation unit 100 is mounted on the base 151 by fitting the
spindle motor 111 in a mid opening 151 so that the spindle 103 is
projected on the upper side of the base 151, and by securing a
stator substrate 110 carrying the spindle motor 111 on the lower
surface of the base 151.
[0064] The disc table 101, mounted on the distal end of the spindle
103 for rotation in unison with the spindle 103, has, on its upper
surface, a disc supporting surface 101a on which to set the hub of
the magnetic disc. The disc table 101 carries a driving pin 104 at
a position offset from the spindle 103. This driving pin 104 is
mounted for movement in a direction emerging from or receded below
the a disc supporting surface 101a and in a direction approaching
to and separated from the disc supporting surface 101a. The driving
pin 104 is biased by biasing means, not shown, in a direction away
from the spindle 103.
[0065] On the disc supporting surface 101a of the disc table 101 is
mounted a ring-shaped magnet 102, such as a rubber magnet, arranged
for surrounding the disc supporting surface 101a. The magnet 102 is
mounted on the disc table 101 so that the magnet is lower in level
than the disc supporting surface 101a.
[0066] On the lower surface of the base 151 is mounted an
electronic circuit board 158 on which are arranged a variety of
electronic circuits or detection switches. On the lower surface of
the base 151 is mounted a lower cover 162 adapted for covering the
lower surface of the electronic circuit board 158.
[0067] On the upper surface of the base 151 provided with the disc
table 101 is mounted a cartridge holder 159 for holding the disc
cartridge and loading the magnetic disc in the disc cartridge on
the disc table 101. The cartridge holder 159 holds the disc
cartridge inserted from the front side of the disc drive device for
moving it to below the base 151 to load the magnetic disc
accommodated in the disc cartridge held thereby onto the disc table
101. The c159 is in the form of a thin casing opened on the front
and lower side and is dimensioned to hold the disc cartridge
inserted from the front side of the disc drive device.
[0068] On the upper surface of the base 151 between the base 151
and the cartridge holder 159 is arranged an uplifting/lowering
plate 160 for uplifting/lowering the cartridge holder 159 towards
and away from the disc rotation unit 110 arranged on the base 151.
On these cams 160a, 160b are set supporting pins 159a protuberantly
formed on both sides of the cartridge holder 159. The cartridge
holder 159 is held at an upper position spaced apart from the disc
table 101 by the supporting pins 159a being supported on the upper
surfaces of cam plates 160a, 160b when the uplifting/lowering plate
160 has been moved in the direction indicated by arrow X1 in FIG. 9
towards the rear side of the base 151. At this time, the disc
cartridge held by the cartridge holder 159 is ejected or a disc
cartridge can be inserted into the cartridge holder 159. Also, when
the uplifting/lowering plate 160 is moved in the direction
indicated by arrow X2 in FIG. 9, towards the front side of the base
151, the supporting pins 159a are moved along the inclined surfaces
of the cam plates 160a, 160b to lower the cartridge holder 159
towards the disc table 101 towards the base 151 in the direction
indicated by arrow J in FIG. 9 in order to load the disc cartridge
held in the cartridge holder 159 on a cartridge loading unit
constructed on the base 151 to load the magnetic disc housed in the
disc cartridge on the disc table 101.
[0069] The uplifting/lowering plate 160 is biased into movement in
the direction indicated by arrow X2 in FIG. 9, under the bias of a
biasing member, not shown. Towards the back side of the base 151 is
provided a lock lever 169 adapted for locking the
uplifting/lowering plate 160 at the rearward moved position when
the uplifting/lowering plate 160 has been moved rearwards in the
direction indicated by arrow X1 in FIG. 9.
[0070] On the forward end face of the base 151 is mounted a front
side panel 164 having a cartridge insertion/ejection opening 165
used for inserting or ejecting a disc cartridge. On this front side
panel 164 are mounted an ejection button opening 167a for
projecting an ejection button 166 and a display light opening 167b
in which to mount a display light 168. When thrust from the front
side of the front side panel 164, the ejection button 166 moves a
movement actuation plate 161 in the direction indicated by arrow X1
in FIG. 9 to shift the uplifting/lowering plate 160 in the same
direction, that is in the direction indicated by arrow X1 in FIG.
9, to move the uplifting/lowering plate 160 in the same direction
as indicated by arrow X1 in FIG. 9 to lock the uplifting/lowering
plate 160 to a lock lever 169.
[0071] Rearwardly of the disc drive device 150 on the base 151 are
arranged a pair of head arms 163, 163 making up a magnetic head
device. On the distal ends of the head arms 163, 163 are mounted a
pair of magnetic heads 191, 191 facing each other. These head arms
163, 163 are biased by biasing means, not shown, into rotation in a
direction in which the distal ends approach towards each other.
That is, the magnetic head 191, 191 are biased in a direction of
approaching to each other. The head arms 163, 163 are moved by a
voice coil motor 192 in the fore-and-aft direction of the base 151
radially of the magnetic disc mounted on the disc table 101, that
is in the direction indicated by arrow J in FIG. 9.
[0072] The disc cartridge is inserted via cartridge
insertion/ejection opening 165 provided in the front side panel 164
into the interior of the disc drive device 150 so as to be held by
the cartridge holder 159. At this time, the shutter mounted on the
disc cartridge is moved for opening the recording and/or
reproducing apertures provided in the upper and lower surfaces of
the disc cartridge. Via these apertures, the magnetic heads 191,
191 mounted on the distal ends of the head arms 163, 163 are
intruded into the interior of the main cartridge body portion for
clinching the magnetic disc held in the main cartridge body portion
between these magnetic head 191, 191.
[0073] When the disc cartridge is inserted into the cartridge
holder 159, the lock lever 169 is thrust by the disc cartridge to
release the locking of the uplifting/lowering plate 160 by the lock
lever 169. The uplifting/lowering plate 160, released from lock by
the lock lever 169, is moved forwardly of the disc drive device
150, that is in the direction indicated by arrow X2 in FIG. 2,
under the biasing by the biasing member. By movement of the
uplifting/lowering plate 160 in the direction indicated by arrow X2
in FIG. 9, the cartridge holder 159 descends towards the disc table
101, that is in the direction indicated by arrow J in FIG. 9. When
the cartridge holder 159 descends towards the disc table 101, the
disc cartridge held by the cartridge holder 159 is supported by a
positioning pin, not shown, provided on a cartridge loading unit
provided in turn on the base 151, for loading the disc cartridge in
position on the cartridge loading unit.
[0074] On the electronic circuit board 158, mounted on the lower
side o the base 151, are mounted a disc-in detection switch 178 and
a write protection detection switch 179 so that operators thereof
are protruded on the upper surface of the base 151, as shown in
FIG. 9. The disc-in detection switch 178 is used for detecting the
possible presence of the disc cartridge, while the write protection
detection switch 179 is used for detecting the state of the write
protection discrimination hole. The disc-in detection switch 178 is
thrust by the disc cartridge when the disc cartridge is loaded on
the cartridge loading unit to detect the loading of the disc
cartridge on the cartridge loading unit. The write protection
detection switch 179 detects the possible presence of the write
protection discrimination hole when the disc cartridge is loaded on
the cartridge loading unit to discriminate whether or not the
information signals can be recorded on the magnetic disc held in
the disc cartridge.
[0075] On the electronic circuit board 158 are mounted disc
capacity detection switches 180a, 180b for detecting the disc
capacity discriminating holes formed in the disc cartridge, as
shown in FIG. 9. These detection switches 180a, 180b are provided
in register with the disc capacity discriminating holes formed in
the disc cartridge loaded on the cartridge loading unit and detect
the possible presence and the positions of the disc capacity
discriminating holes provided in the disc cartridge loaded on the
cartridge loading unit to detect the capacity of the magnetic disc
housed in the disc cartridge.
[0076] When the disc cartridge is loaded on the cartridge loading
unit, the magnetic disc housed within the disc cartridge is set on
the disc table 101 by the hub being attracted by the magnet 102
provided on the disc table 101. At this time, the spindle 103 is
inserted into a spindle opening provided in the hub. The driving
pin 104 is engaged in a chuck pin inserting hole 2d after rotation
of the disc table 101.
[0077] A larger-capacity magnetic disc, as disc-shaped recording
medium of the present invention loaded on the above-described disc
drive device, and a disc cartridge holding this magnetic disc, are
hereinafter explained.
[0078] A first embodiment of the large-capacity magnetic disc 1
according to the present invention is explained with reference to
FIGS. 10 and 11.
[0079] A magnetic disc 1 of the first embodiment of the present
invention includes a disc substrate 3, both major surfaces of which
are coated with a magnetic medium to form signal recording
portions. The disc substrates are formed by a flexible synthetic
resin material, as in the above-described conventional magnetic
disc. That is, the disc substrate 3 is made up of a disc substrate
formed by a thin film of synthetic resin on both major surfaces of
which magnetic films are deposited to form a signal recording
portion. The disc substrate 3 is formed as a disc having the
diameter of 3.5 inch. The disc substrate 3 has a circular center
opening 3a and a hub 2 is mounted for closing this center opening
3a.
[0080] The hub 2, mounted on the disc substrate 3, is formed of a
magnetic material, such as iron, and includes a bottomed tubular
center projection 2a, on the outer rim towards an opening end of
which is formed a flange 2b, as shown in FIG. 11. That is, the hub
2 is substantially in the shape of a saucer. This hub 2 is arranged
on the disc substrate 3 by having a center projection 2a fitted in
a center opening 3a of the disc substrate 3 and is mounted thereon
by bonding the flange 2b on the rim of the center opening 3a. The
hub 2 is secured to the disc substrate 3 by applying a double-sided
adhesive tape, not shown, to the surface of the flange 2b facing
the disc substrate 3. The double-sided adhesive tape is
substantially coextensive as the flange 2b and is bonded to the
surface of the flange 2b facing the disc substrate.
[0081] The hub 2 mounted on the disc substrate 3 has a circular
spindle opening 2c at a mid position of the bottomed tubular
projection 2a so that the opening 2c is passed through by the
spindle 103 of the disc rotation unit 100 provided on the disc
drive device 150. The spindle opening 2c is formed with the center
thereof in register with the center 01-01 of the hub 2 and is
substantially of the same diameter as the diameter of the spindle
103 in order to permit the spindle 103 to be passed therethrough.
This spindle hole 2c is formed by drawing the magnetic material
making up the hub 2 and has an upstanding wall section 2e on its im
portion, as shown in FIG. 11. The upstanding wall section 2e
carries the peripheral surface of the spindle 103 passed through
the spindle hole 2c in order to permit the spindle 103 to be passed
accurately through the spindle opening 2c.
[0082] In the projection 2a of the hub 2 is bored a driving pin
engagement opening 2d, as a rectangular driving member engagement
opening passed through by a driving pin 104 as a driving member
provided on the disc rotation unit 100. The driving pin engagement
opening 2d is spaced a pre-set distance from the spindle opening
2c. The driving pin engagement opening 2d is provided for enabling
the magnetic disc 1 to be mounted on the disc rotation unit 100, on
which the center opening magnetic disc can be centered and loaded,
with interchangeability with the conventional magnetic disc 200.
That is, the driving pin engagement opening 2d is used for
preventing the driving pin 104 protruded towards the disc
supporting surface 101a of the disc table 101 from abutting against
the distal end of the projection 2a of the hub 2 to float the hub 2
from the disc table 101 when the magnetic disc 1 of the present
invention is set on the disc supporting surface 101a of the disc
table 101.
[0083] When the magnetic disc 1 of the present invention is loaded
on the disc rotation unit 100 enabling loading the magnetic disc 1
with interchangeability with the magnetic disc 200, the spindle 103
is passed through the spindle opening 2c, with the driving pin 104
being passed through the driving pin engagement opening 2d.
[0084] Meanwhile, the hub 2, mounted on the magnetic disc 1 of the
present invention, is imaginarily divided by an imaginary
chain-dotted line Q1 in FIG. 10 and by an imaginary chain-dotted
line Q2 in FIG. 11 into an inner rim portion 2h and an outer rim
portion 2i. The surface of the inner rim portion 2h of the hub 2
virtually divided by the imaginary lines Q1 and Q2 for facing the
disc table 101 is a setting surface 2j on a hub supporting surface
101a for the hub supporting surface 101a of the disc table 101,
while the surface of the outer rim portion 2i of the hub is a
suction surface 2k facing the magnet 102 provided on the disc table
101, with the setting surface 2j and the suction surface 2k making
up the major surface of the hub 2.
[0085] The technique of increasing the recording capacity of the
magnetic disc 1 according to the present invention is hereinafter
explained. For increasing the recording capacity of the magnetic
disc 1 of the same size as the conventional magnetic disc, it is
necessary to make high density recording of the information
signals. For high-density recording of information signals, it is
necessary to reduce the track pitch of the recording tracks. It is
however difficult to realize tracking of the magnetic head for each
recording track to realize a narrow track pitch based on the step
feed of a stepping motor used for feeding the magnetic head as in
the case of the conventional magnetic disc 200.
[0086] Thus, in the magnetic disc 1 having the high recording
capacity according to the present invention, the servo information
is pre-recorded and the tracking servo generally practiced in the
hard disc drive based on the servo information is used.
[0087] In the magnetic disc 1 of the present invention, since the
tracking servo is effectuated on the basis of the servo information
recorded on the magnetic disc 1, there is no necessity of
mechanical centering in which the hub 202 is abutted against the
spindle 221 for centering by exploiting the biasing force of the
driving pin 223 engaged in the driving pin engagement opening 202c
of the hub 202 as in the case of the above-described conventional
magnetic disc 200. That is, since it is unnecessary with the
magnetic disc 1 of the present invention to press the hub 2 against
the spindle 103 for centering, there is no necessity of providing a
corner in the spindle opening 2c of the hub 2 on which the
columnar-shaped spindle 103 is abutted in position. Thus, there is
no necessity of forming the spindle opening 2c to a rectangular
shape such that the spindle opening 2c can be formed to a circular
shape in order to enable passage of the columnar-shaped spindle 103
therethrough.
[0088] Meanwhile, since the hub 202 mounted on the conventional
magnetic disc 200 has a substantially square-shaped spindle opening
202b, there results non-uniform distortion during drawing of
forming the spindle opening 202b. If the hub 202 is subjected to
non-uniform distortion, the hub 202 cannot be set in a stable state
on the disc table such that the magnetic disc cannot be rotated in
stability.
[0089] With the hub 2 used in the magnetic disc 1 of the present
invention, since the spindle opening 2c can be formed to a circular
shape, it is possible to reduce occurrence of distortion during
drawing for forming the hub 2, so that the setting surface 2j on
the hub supporting surface 101a provided on the disc table 101 or
the spindle opening 2c can be machined to high accuracy thus
assuring high precision dimensional control.
[0090] By having the circular spindle opening 2c of the hub 2, the
tensile force in the hub 2 produced at the time of molding the hub
2 by drawing a magnetic material becomes uniform, so that the
distortion from the spindle opening 2c to the setting surface 2j,
if produced, is uniform, thus sufficiently improving the surface
accuracy of the setting surface 2j as compared to the conventional
system.
[0091] Thus, with the magnetic disc of the present invention, since
the setting surface 2j on the hub supporting surface 101a of the
disc table 101 can be improved in accuracy, the magnetic disc 1 can
be set in stability on the disc table 101 so that stable-state
rotation free of planar oscillations during rotation is assured to
eliminate a problem which otherwise worsens the follow-up
characteristics of the magnetic heads 191, 191 relative to the
signal recording portion.
[0092] The servo information for effectuating tracking servo is
hereinafter explained.
[0093] On the signal recording portion on the major surface of the
disc substrate 3 of the magnetic disc 1 according to the present
invention is recorded the servo information. In the signal
recording portion are formed concentric recording tracks TR1, TR2,
Trk, . . . , Trm, as shown in FIG. 12. Each of the recording tracks
TR1, TR2, . . . , Trk, . . . , Trm is made up of equiangular servo
frames SF1, SF2, . . . , SF8, . . . , SFn arrayed in the
circumferential direction. The number n of the servo frames is
herein 96. Each servo frame is constituted by a servo area SA and a
data area DA. In the servo area SA are recorded the circumferential
position information, representing the position information of
servo frames, track numbers of the track position information and
tracking signals made up of burst signals for tracking servo.
[0094] FIG. 13 shows an example of the servo area SA. The servo
area SA is made up of an automatic gain control signal (AGC)
signal, a servo timing mark (STM), a grey code area GA and an area
SA2 having recorded therein burst patterns BP.sub.A, BP.sub.B,
BP.sub.C and BP.sub.D for tracking servo. The AGC signals are used
in the disc drive device 150 constructed as shown in FIG. 9 for
controlling the AGC amplifier for signals reproduced by the
magnetic heads 191, 191. The servo timing marks STM are used for
detecting the timing of the servo patterns.
[0095] The burst patterns BP.sub.A, BP.sub.B, BP.sub.C and BP.sub.D
are pattern signals each recorded with a sole frequency. The burst
patterns BP.sub.A, BP.sub.B, BP.sub.C and BP.sub.D are each formed
at a width TP (TP being track pitch) along the center axis of the
track. The C-layer burst pattern BP.sub.C is formed with its center
aligned with the center of an odd-numbered track, while the D-layer
burst pattern BP.sub.D is formed with its center aligned with the
center of an even-numbered track. The A-layer burst pattern
BP.sub.A and the B-layer burst pattern BP.sub.B are formed by
offsetting the C-layer burst pattern BP.sub.C and the D-layer burst
pattern BP.sub.D by TP/2 along the radial direction.
[0096] Since the burst patterns BP.sub.A, BP.sub.B, BP.sub.C and
BP.sub.D for tracking servo are pre-recorded on the magnetic disc 1
of the present invention, as described above, there is no necessity
of effectuating centering about the spindle by interengagement of
the driving pin and the driving pin engagement opening as in the
conventional magnetic disc. Thus, in the magnetic disc 1 according
to the present invention, there is no necessity of effectuating
centering about the spindle as in the conventional system so that
there is no necessity of providing the driving pin engagement
opening 2d. Therefore, with the magnetic disc 1 of the present
invention, there is no necessity of providing a driving pin
engagement opening for mechanical centering about the spindle.
However, in order for the magnetic disc 1 to be loaded with
interchangeability on the conventional disc drive device 150
capable of loading the conventional magnetic disc 200 thereon,
there is formed the driving pin engagement opening 2d in the hub
2.
[0097] Since the servo information for effectuating tracking servo
is pre-recorded on the magnetic disc according to the present
invention, tracking of the magnetic head 191, 191 with respect to
each recording track can be achieved even if the magnetic disc 1
according to the present invention is loaded on the disc table 101
in a state devoid of mechanical centering in which, with the
driving pin 104 inserted through the driving pin engagement opening
2d and with the driving pin 104 pressed against the peripheral
surface of the driving pin engagement opening 2d to press the
spindle 103 against the spindle opening 2c. That is, with the
magnetic disc 1 of the present invention, tracking servo can be
realized based on the servo information pre-recorded in the signal
recording portion even in the absence of the mechanical centering
with respect to the disc table 101.
[0098] With the magnetic disc 1 of the present invention, tracking
servo can be realized on the basis of the servo information
pre-recorded on the signal recording portion, it is unnecessary for
the spindle 103 of the disc rotation unit 100 to have a tight fit
in the spindle opening 2c of the hub 2. That is, there may be left
a gap between the spindle 103 and the spindle opening 2c within a
range of realizing tracking servo based on the servo information.
By providing the gap between the spindle 103 and the spindle
opening 2c, the spindle 103 can be easily interengaged with the
spindle opening 2c. If the diameter of the spindle 103 is
4.008.+-.0.007 mm, the spindle opening 2c can have an inner
diameter slightly larger than the maximum tolerance value of the
diameter of the spindle 103.
[0099] Similarly to the conventional magnetic disc 200, the
magnetic disc 1 according to the present invention is formed using
a flexible disc substrate 3. Therefore, it is liable to be damaged.
Thus, similarly to the conventional magnetic disc 200, the magnetic
disc 1 of the present invention is formed as a disc cartridge 10
held in the main cartridge body portion 13, and is loaded on the
loading unit within the disc drive device 150 as it is housed in
the disc cartridge 10. The magnetic disc 1, housed in the disc
cartridge 10, is loaded on the disc table 101 of the disc rotation
unit 100 as the disc is held in the disc cartridge 10.
[0100] The disc cartridge 10 of the present invention, holding the
magnetic disc 1 according to the present invention, has a
rectangular main cartridge body portion 13 obtained on abutting and
interconnecting an upper cartridge half 11 and a lower cartridge
half 12, obtained on molding a synthetic resin material containing
an anti-static agent, such as an ABS resin, and holds the magnetic
disc 1 in the main cartridge body portion 13, as shown in FIG. 15.
The upper cartridge half 11 and the lower cartridge half 12 are
abutted to form the main cartridge body portion 13, with welding
projections 25, 26 and upstanding peripheral wall sections abutting
to each other, and by bonding the abutting portions together by
ultrasonic welding.
[0101] At a mid portion of the lower cartridge half 12 constituting
the lower surface of the main cartridge body portion 13 is formed a
circular center opening 15, as shown in FIG. 17. The rim of the
inner surface of the circular center opening 15 is formed as-one
with an annular projection 16. The magnetic disc 1 is housed in the
main cartridge body portion 13 by having the hub 2 fitted in the
circular center opening 15 and by having a portion in register with
the flange 2b of the hub 2 supported by the annular projection
16.
[0102] At a mid portion on the inner surface of the upper cartridge
half 11 constituting the upper surface of the main cartridge body
portion 13 is protuberantly formed an annular projection 17 engaged
with the inner rim of the hub 2 mounted on the magnetic disc 1. The
magnetic disc 1 housed in the main cartridge body portion 13 has
its movement in a direction parallel to its major surfaces limited
by the annular projection 17 engaged with the hub 2. The outer
peripheral side of the annular projection 17 is formed with an
annular projection 18 constituting a mounting portion for a
protective sheet as later explained.
[0103] The inner surfaces of the upper and lower halves 11, 12 are
formed with four protuberant arcuate ribs 19, 20 inscribing the
upper and lower halves 11, 12. These ribs 19, 20 are abutted to one
another to constitute a disc housing section. The magnetic disc 1
is housed in the main cartridge body portion 13 by being housed
within the disc housing section defined by the ribs 19, 20.
[0104] Since the distance from the center of the circular center
opening 15 of the lower cartridge half 12 to the ribs 19, 20 is
slightly larger than the radius of the magnetic disc 1, the hub 2
can be fitted with allowance in the circular center opening 15 so
that the rim of the magnetic disc 1 is not contacted with the ribs
19, 20 even if the magnetic disc 1 is moved slightly in a direction
parallel to its major surface.
[0105] In the facing positions of the upper and lower halves 11, 12
of the main cartridge body portion 13 in a mid portion in the
left-and-right direction are formed rectangular apertures 21, 22
for the magnetic head for extending from the vicinity of the center
portion as far as the front side of the main cartridge body portion
13, as shown in FIGS. 16 and 17. The magnetic disc 1 housed in the
main cartridge body portion 13 has its signal recording surface
partially exposed to outside across the inner and outer rims of the
disc.
[0106] On the inner surface of the main cartridge body portion 13
are bonded substantially ring-shaped protective sheets 23, 24
formed by, for example, non-woven cloths. These protective sheets
23, 24 prevent the signal recording surface of the magnetic disc 1
from contacting with the inner surface of the main cartridge body
portion 13 formed by synthetic resin to injure the main cartridge
body portion 13. The portions of the protective sheets 23, 24 in
register with the apertures 23, 24 are formed with radially
extending cut-outs 24a for not closing the apertures 21, 22.
[0107] The main cartridge body portion 13 is provided with a
mistaken recording inhibiting hole 31, operating as a
discriminating hole for indicating whether or not information
signals recorded on the magnetic disc held therein can be erased by
overwriting or erasure, and a disc discriminating hole 33 for
indicating that the housed magnetic disc 1 is a magnetic disc of
high recording capacity of the present invention capable of
recording information signals to high density. This disc
discriminating hole 33 is provided at a corner of lateral side of
the main cartridge body portion 13 provided with the apertures 21,
22 for the magnetic head for specifying that the magnetic disc 1
housed therein is of a high recording capacity as shown in FIG. 17.
By this disc discriminating hole 33, it is indicated that the disc
cartridge 10 holds the magnetic disc 1 of the high recording
capacity according to the present invention. By detection of the
disc discriminating hole 33, the disc cartridge is found to be a
magnetic disc 10 holding the magnetic disc 1 of the high recording
capacity.
[0108] The disc cartridge 10 according to the present invention
mounts a shutter member 14 adapted for opening/closing apertures
21, 22 for a magnetic head. The shutter member 14 is formed by a
plate of metals, such as aluminum or stainless steel, or molded
from a synthetic resin to a U-shaped cross-section, and is fitted
from the front side of the main cartridge body portion 13 for
covering the apertures 21, 22. Moreover, the shutter member 14 is
mounted for movement in a direction of opening or closing the
apertures 21, 22. The shutter member 14 includes shutter portions
14a, 14b formed with apertures 34 which, when the shutter member 14
is moved to a position of opening the apertures 21, are in register
with the apertures 21, 22.
[0109] The magnetic disc 1 according to the present invention,
rotatably housed in the disc cartridge 10, is inserted into the
disc drive device 150 as it is housed in the disc cartridge 10, and
is loaded on the disc table 101 of the disc rotation unit 100.
[0110] Reference is had to FIG. 18 which shows a block circuit
diagram of the disc drive device 150 of FIG. 9 on which the
magnetic disc 1 according to the present invention or the
conventional magnetic disc can be used selectively. In FIG. 18,
only the reproducing system is shown, while the recording system is
omitted for simplicity.
[0111] A disc recording/reproducing apparatus 50 includes magnetic
heads 191, 191 for reproducing information signals recorded in the
signal recording portion of the magnetic disc according to the
present invention or the conventional magnetic disc 200, and an AC
amplifier 52 for amplifying playback signals outputted by the
magnetic heads 191, 191 to a predetermined value to output the
amplified signals. The disc recording/reproducing apparatus 50 also
includes a digital signal processing circuit 53 for digitizing and
outputting playback signals amplified by the AGC amplifier 52 and a
PLL circuit 54 for detecting clock signals from the digital signals
from the digital signal processing circuit 53 for synchronization.
The disc recording/reproducing apparatus 50 also includes a decoder
55 for decoding the digital signals synchronized by the PLL circuit
54 and an ECC circuit 56 for correcting the digital signals decoded
and outputted by the decoder 55 and a RAM 57 for temporarily
storing the digital signals outputted by the ECC circuit 56. The
disc recording/reproducing apparatus 50 also includes an interface
58 for effectuating output control of the digital signals stored in
the RAM 57 to the host computer.
[0112] The disc recording/reproducing apparatus 50 also includes a
rectifier circuit 59 for rectifying and outputting reproduced
signals from the magnetic heads 191, 191, and a PLL circuit 60 for
detecting and synchronizing clock signals from the playback signals
outputted by the rectifier circuit 59. The disc
recording/reproducing apparatus 50 also includes a servo timing
mark (STM) detection circuit 61 for detecting servo timing marks
contained in a signals from the PLL circuit 60 for outputting
signals synchronized with the servo timing, and a grey code area
detection circuit 62 synchronized with the synchronization signal
outputted by the STM detection circuit 61 to read the servo frame
information recorded in the grey code area of the disc. The disc
recording/reproducing apparatus 50 also includes a digital signal
processing (DSP) circuit 63 for discriminating and processing the
information in the grey code area detected by the grey code area
detection circuit 62. The disc recording/reproducing apparatus 50
also includes a tracking error detection circuit 66 for detecting
tracking error signals based on the output signal of the rectifier
circuit 59 and a mixing circuit 67 for sending to the magnetic
heads 191, 191 an output signal of the DSP circuit 63, for example,
a track seek signal, and the tracking error signal outputted by the
tracking error detection circuit 66, to the magnetic heads 191,
191. The disc recording/reproducing apparatus 50 additionally
includes a spindle motor 111 for rotationally driving the magnetic
disc 1. By having this configuration, the disc drive device 150 can
selectively use the magnetic disc 1 according to the present
invention or the conventional magnetic disc 200 and can also apply
tracking servo to the high recording capacity magnetic disc 1
according to the present invention.
[0113] Referring to FIGS. 19 and 20, a second embodiment of the
magnetic disc of the present invention is explained.
[0114] FIGS. 19 and 20 show a magnetic disc 71 which, similarly to
the above-described magnetic disc 1, has a disc substrate 73 which
is formed by a flexible synthetic resin film. That is, the disc
substrate 3 has a signal recording portion of magnetic films
deposited on both major surfaces of the disc substrate formed by a
thin film of synthetic resin. The disc substrate 73 is formed as a
circle 3.5 inch in diameter. The disc substrate 73 includes a
circular center opening 73a. A hub 72 is mounted for closing the
circular center opening 73.
[0115] The hub 72, mounted on the disc substrate 73, includes an
inner rim portion 72f, having a circular outer shape, and an outer
rim portion 72g of a circular outer shape formed on the outer rim
side of the inner rim portion 72f. The hub 72 also includes a
connecting portion 72h, interconnecting the inner rim portion 72f
and the outer rim portion 72g interconnecting the inner and outer
rim portions 72f and 72g, and a flange 72e formed on the outer rim
of the outer rim portion 72g, as shown in FIGS. 19 and 20. This hub
2 is mounted on the disc substrate 73 by inserting the inner and
outer rim portions 72f and 72g through a center opening 73a
provided in the disc substrate 73, retaining the flange 72e on the
rim of the circular center opening 73a of the flange 72e and by
bonding the retained portions such as with an adhesive.
[0116] That is, the hub 72 is formed to a bottomed saucer shape and
is mounted on the disc substrate 73 by bonding the flange 72e on
the outer rim of the end of the outer rim portion 72g to the rim of
the circular center opening 73 a provided on the disc substrate 73
and by securing the inner and outer rim portions 72f and 72g to the
disc substrate 73 so that the inner and outer rim portions 72f and
72g are protruded from the disc substrate 73.
[0117] The outer rim portion 72g is formed so as to be protruded a
distance L from the inner rim portion 72f from the major surface of
the disc substrate 73. The amount of protrusion L from the inner
rim portion 72f of the outer rim portion 72g is selected to, for
example, 0.25 mm. This outer rim portion 72g serves for adjusting
the distance from the magnet 102 provided on the disc table 101 of
the disc rotation unit 100 for adjusting the fore of suction of the
hub 72 of the magnet 102 on loading the magnetic disc 71 on the
disc table 101.
[0118] In the center of the hub 72 is formed a spindle opening 72c
passed through by the spindle 103 provided on the disc rotation
unit 100 when the magnetic disc 71 is mounted on the disc rotation
unit 100. This spindle opening 72c is circular in profile to permit
the spindle 103 to be passed therethrough, as in the
above-described magnetic disc 1. There is provided in the hub 2 a
chuck pin engagement opening 72d at a position offset from the
center so as to be spaced a predetermined distance from the spindle
opening 72c. On the surface of the flange 72e facing the disc
substrate 73 is bonded a double-sided adhesive sheet substantially
coextensive as the flange 72e. The hub 72 is bonded by this
double-sided adhesive sheet to the disc substrate 73.
[0119] The hub 72, mounted on the disc substrate 73, has an outer
surface of the inner rim portion 72f projected from the disc
substrate 73 as a setting surface 72a for the hub supporting
surface 101a provided on the disc table 101 of the disc rotation
unit 100. The outer surface of the outer rim portion 72g protruded
from the inner rim portion 72f is a suction surface 72b facing the
magnet 102 provided on the disc table 101.
[0120] With the hub 72 used for the magnetic disc 71, since the
spindle opening 72c is circular in shape, the hub 72 used for the
magnetic disc 71 suffers for distortion during drawing for forming
the hub 72, only to a lesser extent. Thus, the suction surface 72a
for the hub supporting surface 101a provided on the disc table 101,
suction surface 72b of the magnet 72 or the spindle opening 72c can
be machined highly accurately to assure a high degree of
dimensional accuracy. Specifically, by having the circular spindle
opening 72c of the hub 72, the tensile force in the hub 72
generated during formation of the hub 72 by drawing a magnetic
material is uniform, so that distortion occasionally produced from
the spindle opening 72c to the setting surface 72a and to the
suction surface 72a is uniform thus sufficiently improving the
surface accuracy of the setting surface 72a and the suction surface
72b as compared to those in the conventional system.
[0121] On the rim of the spindle opening 72c, there is formed an
upstanding wall section 72k simultaneously with drawing of the
spindle opening 72c. This upstanding wall section 72k supports the
peripheral surface of the spindle 103 inserted into the spindle
opening 72c to realize stable insertion of the spindle 72 into the
spindle opening 72c.
[0122] Since the magnetic disc 71, similarly to the magnetic disc
1, is constituted using the flexible disc substrate 73, it is
susceptible to damages. Thus, the magnetic disc 71 of the present
embodiment, similarly to the above-described magnetic disc 1, is
constituted as a disc cartridge 10 held in the main cartridge body
portion 13, and is loaded on the cartridge loading unit in the disc
drive device 150 in a state of being held in the disc cartridge 10.
The magnetic disc 1, held in the disc cartridge 10, is loaded on
the disc table 101 of the disc rotation unit 100 as it is held in
the disc cartridge 10.
[0123] The disc cartridge 10, holding the magnetic disc 71 shown in
the present embodiment, includes a main cartridge body portion 13,
formed by abutting and connecting the upper cartridge half 11 and
the lower cartridge half 12 to each other, and holds a magnetic
disc 71 for rotation therein, as shown in FIGS. 21 to 23.
[0124] The structure of the main cartridge body portion 13 is
common to that shown in FIGS. 15 to 17 so that common portions are
depicted by the common numerals and the detailed description is
omitted for clarity.
[0125] The magnetic disc 71 is held in the main cartridge body
portion 13 by having the hub 72 fitted in the circular center
opening 15 and by having its portion in register with the flange
72e of the hub 72 supported by the annular projection 16, as shown
in FIGS. 21 and 23. At this time, the hub 72 mounted on the
magnetic disc 71 has its outer rim portion 72g projected to the
lower side of the main cartridge body portion 13 more prominently
than its inner rim portion 72f, when looking from the side of the
circular center opening 15 which is the lower side surface of the
main cartridge body portion 13.
[0126] This main cartridge body portion 13 similarly has a mistaken
recording inhibiting hole 31 for indicating whether or not the
information signals recorded on the magnetic disc 71 held therein
can be erased by overwriting or erasure and a disc discriminating
hole 33 for indicating that the magnetic disc 1 of high recording
capacity is held therein, as shown in FIGS. 22 and 23.
[0127] The state of mounting the magnetic disc 71 of the present
embodiment on the disc table 101 of the disc rotation unit 100 is
explained with reference to FIGS. 24 and 25.
[0128] In these figures, only the magnetic disc 71 is shown, while
the main cartridge body portion 13 is omitted from the drawing.
[0129] The magnetic disc 71 is inserted into the disc drive device
as the disc is held in the disc cartridge 10. The disc cartridge
10, inserted into the disc drive device, is held by the cartridge
holder 159. On insertion of the disc cartridge 10 into the
cartridge holder 159, the latter is lowered to the disc rotation
unit 100 so as to be loaded in position on the cartridge loading
unit provided on the base 151. As the disc cartridge 10 is loaded
on the cartridge loading unit, the magnetic disc 71 housed in the
disc cartridge 10 is lowered towards the disc rotation unit 100 in
the direction indicated by arrow Z in FIG. 24 so as to be set on
the disc table 101 constituting the disc rotation unit 100. At this
time, the setting surface 72a formed on the inner rim portion 72f
of the hub 72 of the magnetic disc 71 is supported on the hub
supporting surface 101a of the disc table 101, while the suction
surface 72b of the outer rim portion 72g formed with a step
difference on the outer rim of the inner rim portion 72f faces the
facing surface 102a at a pre-set distance H.
[0130] At this time, the spindle 103 is passed through the spindle
opening 72c of the hub 72, with the driving pin 104 being inserted
through the driving pin engagement opening 72d.
[0131] Meanwhile, with the hub 202 mounted on the conventional
magnetic disc 200, since the setting surface 202e on the disc
supporting surface of the disc table is flush with the outer
peripheral surface of the disc supporting surface 222a facing the
magnet, the distance H0 between the surface of the hub 202 facing
the magnet 224 and the surface of the magnet 24 is substantially
equal to the distance between the disc supporting surface 222a and
the magnet 224, when the hub is set on the disc table 222, as shown
in FIG. 4. Also, the hub 2 mounted on the disc table 101 of the
first embodiment, has a setting surface 2j for the hub supporting
surface 101a of the disc table 101, and a surface facing the disc
table 101 of the outer rim portion 2i is flush with the suction
surface 2k facing the magnet 102 provided on the disc table 101, so
that the distance H0 between the suction surface 2k of the hub 202
facing the magnet 224 and the surface of the magnet 224 is
substantially equal to the distance between the setting surface 2i
and the magnet surface.
[0132] Conversely, with the hub 72 of the second embodiment of the
magnetic disc 72 of the present invention, since the suction
surface 72b of the outer rim portion 72g is protruded by the
distance L from the hub supporting surface 101a of the inner rim
portion 72f, the hub 72 is closer by this distance L to the facing
surface 102a than the hub 202 of the magnetic disc 200 or the hub 2
of the magnetic disc 1 of the first embodiment, so that the force
of suction is larger than in the case of the conventional magnetic
disc 200 or the magnetic disc 1 of the first embodiment, with the
force of holding of the magnetic disc 71 to the disc table 101 thus
being larger.
[0133] The reason the force of suction with respect to the disc
table 101 needs to be increased for the high recording capacity
type magnetic disc 71 is explained.
[0134] The magnetic disc 71 of large recording capacity is rotated
at an elevated speed for recording and/or reproducing information
signals. In the disc drive device 150 employing the magnetic disc
71 of large recording capacity, the magnetic disc 71 needs to be
rotated at an elevated speed. In the disc drive device 150, the
magnetic disc 71 needs to be positively unified with respect to the
disc table 101 even if the magnetic disc 71 is rotated at a high
speed. For positively unifying the magnetic disc 71 to the disc
table 101 even under high speed rotation of the disc, the hub 72
needs to be sucked and held by the disc table 101 with a larger
force of suction. For raising the force of suction of the hub 72,
it may be contemplated to raise the magnetic force of the magnet
102 provided on the disc table 101. However, if the magnetic force
of the magnet 102 is increased, there is a risk that centering
cannot be achieved when the conventional magnetic disc 200 is used.
That is, there is not produced slip between the magnetic disc 200
and the disc table 101 such that the driving pin 104 cannot be
pressed against the driving pin engagement opening 202c while the
spindle 103 cannot be pressed against the spindle opening 202b. If
the conventional magnetic disc 200 is loaded, and the magnetic
force of the magnet 102 is reduced for enabling centering of the
magnetic disc 200 with respect to the spindle 103, it becomes
difficult to chuck the magnetic disc 71 of large recording capacity
rotating at a high speed with respect to the disc table 101.
[0135] In the magnetic disc 71 of the second embodiment of the
present invention, since the suction surface 72b of the outer rim
portion 72g is protruded downwards by the distance L from the hub
supporting surface 101a of the inner rim portion 72f, the suction
surface 72b can be approached to the magnet 102 provided on the
disc table 101 a distance corresponding to this amount, so that,
with the same magnetic force of the magnet 102, the force of
suction for the magnet 102 can be made higher than that in the case
of the conventional magnetic disc 200. That is, since the second
embodiment of the magnetic disc 71 of the present invention has the
suction surface 72b closer to the magnet 102 of the disc table 101,
it becomes possible to increase the suction of the conventional
magnetic disc 200 with respect to the disc table 101 so that the
magnetic disc can be unified to the disc table 101 even under
high-speed rotation.
[0136] Moreover, with the hub 72 used in the second embodiment of
the magnetic disc 71 of the present invention, the surface of the
inner rim portion 72f formed with a step on the inner rim of the
outer rim portion 72g serves as the setting surface 72a on the disc
table 101, so that the setting surface can be reduced in diameter
as compared to the setting surface 202e of the hub 202 of the
conventional magnetic disc 200 on the disc table 101 thus assuring
high degree of planarity. Moreover, since the spindle opening 72c
provided at the center of the inner rim portion 72f is circular in
profile, there is no risk of the setting surface 72a becoming
distorted to render it possible to maintain high planarity.
* * * * *