U.S. patent application number 10/092898 was filed with the patent office on 2002-07-18 for magnetic disk drive and magnetic disk drive system.
This patent application is currently assigned to Hitachi, Ltd.. Invention is credited to Akira, Chuma, Ishigaki, Tatsuya, Iwakura, Masao, Kodama, Naoki, Kojima, Toshiaki, Kugiya, Fumio, Nakagoshi, Kazuo, Ogawa, Takuji, Okunaga, Nobuyuki, Sakai, Kazuo, Suzuki, Tomio.
Application Number | 20020093760 10/092898 |
Document ID | / |
Family ID | 26484702 |
Filed Date | 2002-07-18 |
United States Patent
Application |
20020093760 |
Kind Code |
A1 |
Okunaga, Nobuyuki ; et
al. |
July 18, 2002 |
Magnetic disk drive and magnetic disk drive system
Abstract
A magnetic disk drive that shape coefficient is 3.5 inches are
provided, which is designed as rotating magnetic media in a high
speed in order to consume a low electric power, to generate a less
heat, and to access more quickly. When magnetic disk media are
rotated in a higher speed, an electric power consumption and a heat
generation are increased because of a load increase in rotating the
magnetic disk media. An avoidance of such problems and setting an
additional special cooling mechanism to magnetic disk drive
systems, for example, disk array systems, is presented. A housing
11 of magnetic disk drive in a shape coefficient 3.5 inches mounts
magnetic disk media 21 for a magnetic disk drive in a shape
coefficient 2.5 inches, which aims a lightweighting of a rotational
spindle portion, a decrease of a torque loss during on-load
rotation with the media, and a decrease of a electric current into
a spindle motor 41 during rotation. Further, fins 11a for heat
radiation may be arranged around the housing 11, which results in
avoidance or decrease raising a temperature in the housing 11.
Inventors: |
Okunaga, Nobuyuki;
(Odawara-shi, JP) ; Iwakura, Masao; (Odawara-shi,
JP) ; Nakagoshi, Kazuo; (Odawara-shi, JP) ;
Ogawa, Takuji; (Odawara-shi, JP) ; Akira, Chuma;
(Ashigarashimo-gun, JP) ; Kugiya, Fumio;
(Odawara-shi, JP) ; Suzuki, Tomio; (Hiratsuka-shi,
JP) ; Kojima, Toshiaki; (Odawara-shi, JP) ;
Sakai, Kazuo; (Niihari-gun, JP) ; Kodama, Naoki;
(Kamakura-shi, JP) ; Ishigaki, Tatsuya;
(Yokohama-shi, JP) |
Correspondence
Address: |
MATTINGLY, STANGER & MALUR, P.C.
1800 DIAGONAL ROAD
SUITE 370
ALEXANDRIA
VA
22314
US
|
Assignee: |
Hitachi, Ltd.
|
Family ID: |
26484702 |
Appl. No.: |
10/092898 |
Filed: |
March 8, 2002 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
10092898 |
Mar 8, 2002 |
|
|
|
09185969 |
Nov 5, 1998 |
|
|
|
Current U.S.
Class: |
360/97.15 ;
G9B/25.003; G9B/33.038 |
Current CPC
Class: |
G11B 33/142 20130101;
G11B 5/012 20130101; G11B 25/043 20130101 |
Class at
Publication: |
360/97.01 |
International
Class: |
G11B 017/00 |
Foreign Application Data
Date |
Code |
Application Number |
Nov 7, 1997 |
JP |
09-306064 |
Jun 5, 1998 |
JP |
10-157145 |
Claims
We claim:
1. A magnetic disk drive, comprising: magnetic disk media recording
information; a hub holding said magnetic disk media rotatablly; a
spindle motor rotating said hub; a magnetic head recording or
reproducing information to or from said magnetic disk media; an
actuator holding and locating said magnetic head at a predetermined
position on said magnetic disk media; and a housing in a shape of
3.5 inches form factor size, mounting said magnetic disk media,
said hub, said magnetic head and said actuator; wherein said
magnetic disk media held on said hub, are smaller in diameter than
magnetic disk media those are used for 3.5 inches form factor
magnetic disk drive.
2. A magnetic disk drive according to claim 1, wherein said spindle
motor rotates 10000 rpm or more.
3. A magnetic disk drive according to claim 2, further comprising
fins arranged around said magnetic disk media.
4. A magnetic disk drive, comprising: magnetic disk media recording
information; a hub holding said magnetic disk media rotatablly; a
spindle motor rotating said hub; a magnetic head recording or
reproducing information to or from said magnetic disk media; an
actuator holding and locating said magnetic head at a predetermined
position on said magnetic disk media; and a housing in a shape of
3.5 inches form factor size, mounting said magnetic disk media,
said hub, said magnetic head and said actuator; wherein said
magnetic disk media held on said hub, are not greater in diameter
than shape-coefficient 2.5 inches' magnetic disk media.
5. A magnetic disk drive according to claim 4, wherein said spindle
motor rotates 10000 rpm or more.
6. A magnetic disk drive according to claim 1, wherein said hub and
said actuator are arranged so that a distance between a rotation
center of said hub and a swing center of said actuator is at most
40 milli meters .+-.1 milli meters.
7. A magnetic disk drive according to claim 1, wherein said hub and
said actuator are arranged so that a distance between a rotation
center of said hub and a swing center of said actuator is between
40 milli meters and 47.5 milli meters.
8. A magnetic disk drive according to claim 6 or claim 7, wherein
an average access time in locating said magnetic head to said
predetermined position on said magnetic disk media, is not greater
than 7.5 milli seconds when a torque of said actuator is at least
0.12 Newton.meter per one ampere current.
9. A magnetic disk drive according to claim 6 or claim 7, wherein
an average access time in locating said magnetic head to said
predetermined position on said magnetic disk media, is not greater
than 7.5 milli seconds when a weight of rotational portion at said
actuator is not greater than 36 gram.force.
10. A magnetic disk drive according to claim 4 further comprising
fins arranged around said magnetic disk media.
11. A magnetic disk drive according to claim 3 or claim 10, wherein
said fin is a member having unlevel, washboard or jaggy portion in
cross sectional view which is given if said fin is cut by a plane
along a rotational axis of said hub.
12. A magnetic disk drive according to claim 3 or claim 10, wherein
said fin is casted en bloc with said housing.
13. A magnetic disk drive system, comprising: a case mounting and
securing a plurality of magnetic disk drive according to claim 2;
and a control unit coupling and controling said magnetic disk
drives electrically.
14. A magnetic disk drive system, comprising: a case mounting and
securing a plurality of magnetic disk drive according to claim 3;
and a control unit coupling and controling said magnetic disk
drives electrically.
15. A magnetic disk drive system according to claim 13 or claim 14,
further comprising a fan cooling said plurality of magnetic disk
drive or said control unit.
16. A magnetic disk drive according to claim 4, further comprising
fins arranged around said magnetic disk media along a depth
direction or a width direction of the magnetic disk drive.
17. A magnetic disk drive according to claim 16, wherein fins
arranged along said depth direction exclusively or along said width
direction, have plural rows arranged one another at different
positions in the thickness direction of the magnetic disk
drive.
18. A magnetic disk drive according to claim 16, wherein remain
fins arranged along said width direction exclusively or along said
depth direction, have one row or two rows.
19. A magnetic disk drive according to claim 3 further comprising a
fan making an air flow in a depth direction or a width direction of
the magnetic disk drive.
20. A magnetic disk drive according to claim 10, wherein said
housing has a hole to record a servo signal to said magnetic disk
media.
21. A magnetic disk drive system, comprising: a case mounting and
securing a plurality of magnetic disk drive according to claim 4,
claim 10, or claim 19; and a control unit coupling and controling
said magnetic disk drives electrically.
Description
BACKGROUND OF THE INVENTION
[0001] 1. Field of the Invention
[0002] A present invention relates to a magnetic disk drive,
particularly, rotating a magnetic disk medium in a high speed and a
magnetic disk drive system using this technique.
[0003] 2. Description of the Related Art
[0004] In a magnetic disk drive system that is used as a high
precision external storage, for example, a computer, a file server
or a disk array, it is well known that by a magnetic head that
flies with a given distance over a recording surface of a magnetic
disk medium in the magnetic disk drive system, a dedicated
information is recorded on or reproduced from the magnetic disk
medium via a magnetic flux.
[0005] A performance of magnetic disk drives greatly comes to
decide a throughput of the magnetic disk drive system in the recent
years. For better performance, there are next universal aims in the
improvement of the system.
[0006] 1) a memory capacity improvement within a limited system
hardware Increase of an information storage capacity per unit
volume)
[0007] 2) retrenchment of time for moving a magnetic head to a
dedicated truck on the magnetic disk medium (Shortening of seek
time)
[0008] 3) retrenchment of waiting time in rotation for waiting a
magnetic head to a dedicated location at the specified position on
a truck of the magnetic disk medium
[0009] These items were resolved in the present invention by an
increase of rotational speed of the magnetic disk media, which also
increases an input-output transfer rate of information between
magnetic disk drive and upper system ,and between magnetic disk
drive system and upper system.
[0010] There is a "3.5 inches" drive in short from the past. Here,
"3.5 inches" is called shape coefficient. "3.5 inches" size means a
magnetic disk drive which has an about 4 inches (101.6 mm) in
width, an about 5.75 inches (146.1 mm) in length. It usually has an
about 1 inch height unless otherwise specified.
[0011] In case a rectangular parallelepiped circumscribes a
magnetic disk drive, let's imagine the largest face that is
parallel to the magnetic disk medium. At this time, the largest
face of the "3.5 inches" drive can include two largest faces of a
"2.5 inches" drive. Similarly, a largest face of the "5 inches"
drive can include two largest faces of a "3.5 inches" drive. The
shape that falls in the above relationship, golden section, is
called a form factor size.
[0012] The conventional "3.5 inches" magnetic disk drive has a
structure, in a housing with 3.5 inches shape coefficient, which
comprises: an arm than supports magnetic head parts, a carriage
with the arm, which positions the magnetic head to the specified
location on the magnetic disk media, an in-hub-type spindle motor
that has rotational mechanism within a hub that holds the magnetic
disk media on its outer surface, and magnetic disk media of which
most outside diameter is 95 mm stacked on the hub (hereinafter
called "3.5 inches" disk for short).
[0013] Here, there are "3.5 inches" magnetic disk drives which have
mainly about 1 inch (25.4 mm) height or about 1.63 inches (41.4 mm)
height.
[0014] FIG. 3 shows an inner structure (plan view) of prior "3.5
inches" magnetic disk drive. External size of the housing 13 is a
3.5 inches form factor size (101.6 mm.times.146 mm). Magnetic disk
media 23 are secured by a disk clamp 33 to a spindle motor 43,
which are rotated at predetermined speed in this housing.
[0015] Magnetic heads 53 are secured to an edge of an actuator (the
carriage and a coil) 63. The actuator 63 is secured rotatably by a
pivot bearing 73 to the housing. The housing 13 secures a voice
coil motor 83 that consists of a magnetic circuit. The coil of the
actuator 63 is flowed by electricity, then it generates a
rotational torque with electromagnetic force and drives the
actuator 63. Consequently, the magnetic head 53 supported at the
edge of the actuator executes a seek operation in which the head
are located at an artbitrary location on the disk media 23 along a
quasi-radial direction.
[0016] In the 1.6 inches height magnetic disk drive with an about
41 mm official height, the spindle motor 43 is mounted stackingly
with eight "3.5 inches" disk media (0.8 mm thickness). In 1 inch
height magnetic disk drive with an about 25.4 mm official height,
it is mounted stackingly with four "3.5 inches" disk media.
[0017] Other prior arts about faster rotating technique of spindle
motors are disclosed, for example, at Japanese Laid opened, sho
63-104282 (corresponding to U.S. Pat. No. 5,243,479) and at
Japanese Laid opened, hei 04-205776 that shows stacking structures
with "3.5 inches" disk media or "2.5 inches" disk media in a
housing of 5.25 inches of shape coefficient.
[0018] Inventors of this application tried to rotate magnetic disk
media of 1.6 inches height magnetic disk drive shown in FIG. 3
faster than in prior arts. They confirmed that when a rotational
speed of spindle motor 43 becomes 10000 rpm from 7200 rpm (prior
rotational speed), electric energy consumption increases with about
60 percent and becomes more than 20 watts despite a lightweight
design review that decreases the disk media 23 from 10 disks to 8
disks in the stack.
[0019] They also confirmed that an inner temperature of the housing
13 becomes more than 80 degree centigrade without cooling means
surrounding the 1.6 inches height magnetic disk drive shown in FIG.
3. The cooling means are, for example, a fan that makes air flow
for cooling.
[0020] Inventors of this application tried to rotate magnetic disk
media of 1.6 inches height magnetic disk drive shown in FIG. 12
faster than in prior arts. When a rotational speed of spindle motor
43 becomes 12000 rpm from 6300 rpm (prior rotational speed),
electric energy consumption increases with about 460 percent.
[0021] Japanese Laid opened, hei 4-205776 shows a magnetic disk
drive that mounts a stack of magnetic disk media smaller in outer
size than that of "5.25 inches" magnetic disk media within a
housing that is designed for a 5.25 inches form factor size
magnetic disk drive. But it does not consider an increase of heat
generation caused from faster rotation and higher density
mounting.
[0022] Japanese Laid opened, sho 63-104282 (corresponding to U.S.
Pat. No. 5,243,479) does not consider fully a heat radiation while
it discloses an increase of rotational speed of magnetic media.
[0023] Inventors of this application mounts magnetic disk media for
"2.5 inches" form factor magnetic disk drives, in the housing for
1.6 inches height "3.5 inches" magnetic disk drive. And further
they rotates the media at 12000 rpm in order to fabricate a
magnetic disk drive with a high transfer rate of information (FIG.
13, FIG. 14). Inventors of this application found that it is
necessary for keeping the inner temperature equal to or lower than
60 degrees centigrade to mount eight disk media or less when 0.8 mm
thickness media are adopted and to mount eleven disk media or less
when 0.635 mm thickness media are adopted. That is, they found that
it is possible to rotate disk media faster with victimizing the
information storage capacity in some extent, and that the storage
capacity and the faster rotation of the media are in the trade-off
relationship.
[0024] Here, disk media for the 2.5 inches form factor magnetic
disk drive have a 65.+-.3 mm diameter (outermost diameter) and a
0.8 mm .+-.0.2 mm thickness or a 0.4 mm.+-.0.2 mm thickness. Normal
thicknesses of the media are 0.8 mm, 0.635 mm or 0.381 mm.
[0025] One of the reasons why the inner temperature of the housing
(during a seek operation) is kept in the predetermined temperature
or less, for example, 60 degree centigrade or less, is to get a
long life of the disk drive by setting an enough margin in
temperature for long lives of a lubricant on the disk media surface
and a grease in bearings of the spindle motor. Another is not to
give a bad influence to a status between the magnetic head and the
magnetic disk media, and to a posture of a slider. Consequently,
recording or reproducing with a information to or from the disk
media are not influenced badly. Thus, temperature specifications of
the magnetic disk drive can be guaranteed.
[0026] Thus, inventors of this application found that it is
necessary for making the stack of media lightweight, for achieving
the faster rotational speed of the media, and for keeping or
increasing the storage capacity, to attach a special cooling
mechanism to the magnetic disk drive.
[0027] In the magnetic disk drive system, for example, the file
server or the disk array, it is desirable for rotating the magnetic
media faster and for keeping the system highly reliable that
cooling means should be provided to the magnetic disk drive.
SUMMARY OF THE INVENTION
[0028] It is an object of the present invention to provide magnetic
disk drives with a big storage capacity and a high reliability,
which rotate the magnetic disk media at a high speed and which
restrain heat generation grown out of the high speed rotation.
[0029] It is other object of the present invention to provide
magnetic disk drives and magnetic disk drive systems with a big
storage capacity and a high speed accessing ability.
[0030] It is other object of the present invention to provide
magnetic disk drives and magnetic disk drive systems with a high
speed accessing ability and a good cost performance.
[0031] Other objects of the present invention may be clear from the
statement of this specification and drawings.
[0032] Achieving the above objects, the magnetic disk drive of the
present invention mounts magnetic disk media smaller in diameter
than "3.5 inches" magnetic disk media within a magnetic disk drive
in a shape coefficient 3.5 inches. For more cost performance, (in
other words, using general-purpose parts that do not come expensive
in stead of custom-order parts), the magnetic disk drive of the
present invention may mount magnetic disk media for drives in a
shape coefficient 2.5 inches, 65 mm media in outer diameter within
the magnetic disk drive in the shape coefficient 3.5 inches.
[0033] Under the above structure, in the housing that is sealed
including the actuator, the spindle motor, etc., around the
magnetic disk media of 65 mm in outer diameter, space of 95 mm-65
mm=30 mm arises. If it says in the distance from the center axis of
the spindle motor that rotates the magnetic disk media, a clearance
of 15 mm arises.
[0034] From the trade off relationship between a performance and a
price of the magnetic disk drive, members for heat radiation may be
arranged in this margin area. Or this radiation member may not be
arranged, resulting in that the magnetic disk drive may have a
margin for parts' arrangement in the above space.
[0035] When the radiation members are arranged, they are composed
to arrange fins (uneven parts) in surrounding periphery of the
magnetic disk medium.
[0036] Distance between the center of the spindle motor that
rotates magnetic disk media of 65 mm in outer diameter, and the
center of the actuator, may be arranged so that it becomes 40.+-.1
mm or less. Further, if cost performance is pursued, if normal
actuator parts are used, and if a torque of the voice coil motor is
increased, the above distance can be extended to 47.5 mm. The
distance may have a margin considering to a windage loss, etc..
[0037] Further, in stead of magnetic disk media of a 65 mm in outer
diameter, a magnetic disk media for a magnetic disk drive in a
shape coefficient 1.8 inches, may be used in the 3.5 inches
magnetic disk drive. The magnetic disk media of 48 mm in outer
diameter are normal media for magnetic disk drives in shape
coefficient 1.8 inches, and its thickness is 0.381 mm.
BRIEF DESCRIPTION OF THE DRAWINGS
[0038] FIG. 1 is a cross-sectional side view of a magnetic disk
drive, which shows a first embodiment of the present invention.
[0039] FIG. 2 shows a plan view of FIG. 1.
[0040] FIG. 3 shows a plan view of prior magnetic disk drive.
[0041] FIG. 4 shows an oblique view of a magnetic disk medium which
has 2.5 inches form factor size in 0.381 mm thickness.
[0042] FIG. 5 shows an oblique view of a magnetic disk medium which
has 1.8 inches form factor size in 0.381 mm thickness.
[0043] FIG. 6 shows a plan view of magnetic disk drive that is the
second embodiment of present invention.
[0044] FIG. 7 is a cross sectional view between A-A portion that
shows a fin shape in FIG. 6.
[0045] FIG. 8 is the second cross sectional view between A-A
portion that shows a fin shape in FIG. 6.
[0046] FIG. 9 is the third cross sectional view between A-A portion
that shows a fin shape in FIG. 6.
[0047] FIG. 10 shows a plan view of the third embodiment of present
invention, which is a magnetic disk drive higher than a normal
height.
[0048] FIG. 11 shows a cross-sectional side view of FIG. 10.
[0049] FIG. 12 is a cross-sectional side view of a magnetic disk
drive, which shows the fourth embodiment of the present
invention.
[0050] FIG. 13 is a side view in depth direction of FIG. 12.
[0051] FIG. 14 is a side view in depth direction of the fourth
embodiment, which shows an air flow.
[0052] FIG. 15 is a side view in width direction of FIG. 12.
[0053] FIG. 16 is a deformed side view in width direction of FIG.
12.
[0054] FIG. 17 is a side view in depth direction of a magnetic disk
drive that shows the fifth embodiment of present invention.
[0055] FIG. 18 is an oblique view of a magnetic disk drive which
shows the fourth embodiment of present invention.
[0056] FIG. 19 is a cross sectional side view of the sixth
embodiment of present invention, which shows a magnetic disk drive
higher than normal.
[0057] FIG. 20 is a side view in depth direction of a magnetic disk
drive that shows the seventh embodiment of present invention.
[0058] FIG. 21 is a side view in depth direction of a magnetic disk
drive that shows the eighth embodiment of present invention.
[0059] FIG. 22 is a side view in width direction of a magnetic disk
drive that shows the ninth embodiment of present invention.
[0060] FIG. 23 is a side view in depth direction of a magnetic disk
drive shown in FIG. 22.
[0061] FIG. 24 is a side view in depth direction of a magnetic disk
drive shown in FIG. 22.
[0062] FIG. 25 is an architecture of a magnetic disk drive system
that mounts the magnetic disk drive of present invention.
[0063] FIG. 26 is an oblique view of a magnetic disk drive of the
fourth embodiment of present invention, which shows a different
spacing in parts-arrangement from a normal magnetic disk drive.
[0064] FIG. 27 shows a plan view of FIG. 26.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0065] FIG. 1 is a cross-sectional view that shows an outline of
the internal structure of the magnetic disk drive, first embodiment
of the present invention. Housing 11 has a 3.5 inches form factor
size with official height of 41.4 mm. "2.5 inches" magnetic disk
media 21 (65 mm in diameter, 0.635 mm in thickness), a spindle
motor 41 that rotates these media 21 in a predetermined rotational
speed, a rotary type actuator 61 that locates the magnetic head
around a pivot bearing 71, and a voice coil motor 81 that drives
the rotary type actuator 61 are secured in this housing 11.
[0066] A securing method of the spindle motor 41 is with a screw or
by a press fit to be secured at one edge of or at both edges of the
spindle motor 41 to the housing 11 that includes the spindle motor
41, or to the housing 11 and a cover 101 that hermetically closes
the inner space of the housing 11. Magnetic disk medium 21 uses Al
(aluminum) or glass for its substrate material. For more economic
fabrication of the magnetic disk drive, in place of screws and
press fits, an adhesive may be used for securing.
[0067] Magnetic disk media 21 are stacked via spacers 141,
thickness of which is 1.7 mm. The space between the media is 1.7
mm. 12 media are stacked in an axial direction. Magnetic disk media
21 are fixed by a disk clamp 31 to the spindle motor 41 that can
rotate to 15000 rpm.
[0068] The 111 axis of the rotary center of magnetic disk media 21
is arranged almost at a central portion of the housing 11. The
housing 11 that is en bloc casted with aluminum alloy, has linear
fins 11a arranged at four portions outside the housing, each of
which fins is defined with a thickness at a leaf edge t=2 mm, a
leaf length L=32 mm, a distance H between leaf edges is 5 mm, and
each of which fins is stood straight against 111 axis of the rotary
center of magnetic disk media 21.
[0069] As magnetic disk media 21 becomes smaller in diameter, for
example, as changing "3.5 inches" disk media to "2.5 inches disk
media in same thickness of 0.8 mm, a weight per one disk medium
reduces by about 54%. As changing "3.5 inches" disk media to 2.5
inches" disk media in other thickness of 0.635 mm, a weight per one
disk medium reduces by about 64%. Therefore, a gross weight the
spindle motor rotates can be reduced, which brings a high
characteristic at a spin-up operation, and which also effects a
reduction of electric current (electric energy consumption during
an idle rotation.
[0070] If magnetic disk media are changed from "3.5 inches" to "2.5
inches", for example, a maximum marginal velocity when the "3.5
inches" disk media rotate at 10000 r.p.m. equals to a maximum
marginal velocity when the "2.5 inches" disk media rotate at 14600
r.p.m. Therefore, when recording or reproducing an dedicated
information to or from the magnetic disk media 21 by a magnetic
head 51 (FIG. 2) via a magnetic flux, if a signal processing
ability is same as in the past or more, faster rotation of the
media can be executed without a reduction of recording density in
longitudinal direction along a track that is located concentrically
on the magnetic disk media 21.
[0071] When magnetic disk media 21 rotate, they receive a
frictional resistance by a viscosity of air that surrounds the
magnetic disk media 21. A transition boundary where an air flow
along a surface of the magnetic disk media becomes from a laminar
flow to a turbulent flow is about 15000 r.p.m. when the magnetic
disk media 21 is "3.5 inches" disk and about 30000 r.p.m. when the
media is "2.5 inches" disk.
[0072] When magnetic disk media 21 are changed from "3.5 inches" to
"2.5 inches", the transition boundary is big enough against the
number of rotation limits of the spindle motor 41. Because an
torque loss during on-load rotation, which is caused from the
frictional resistance, becomes bigger biquadrately proportional to
a diameter of the magnetic disk media, if the spindle rotates the
media in a same speed, the torque loss of "2.5 inches" disk media
corresponds to about 22 of that of "3.5 inches" disk media.
Therefore, when the spindle motor 41 rotates in a predetermined
idle speed, the current (consumption power) becomes smaller, and a
heat generation caused by windage can be restrained.
[0073] Fins 11a are made at plural portions of the housing 11,
which have an effect that increases a surface area of the housing
11 and that makes a heat-penetration flow good. The tips of fins
11a become closer to the temperature of the external air of housing
11. The rotation of spindle motor 41 and the flutter of actuator 61
driven by the system generate a heat, which rises an internal
temperature of the magnetic disk drive. The fins 11a reduce this
temperature increase.
[0074] As for the fins, if the thickness t is 0.5 mm or more, a
radiation coefficient almost never changes. If the length L of the
fins at four portions is made to be 10 mm or more , the radiation
becomes effective. Consequently, the fins can restrain temperature
risings at least with about 5 degree centigrade at 10000 r.p.m.
rotation, about 8 degree centigrade at 12000 r.p.m. rotation, and
about 10 degree centigrade at 15000 r.p.m. rotation. It is
advantageous to make the length L of the fins long as much as
possible. And it can bring a heat penetration flow good to make the
number of the fins big as many as possible, because the surface
area of the fins become broader. And if the fins 11a are arranged
in a air flow made by a fan that is installed in a case of a
magnetic disk drive system on which the magnetic disk drive is
mounted, a cooling of the magnetic disk drive become more
effective.
[0075] a) Power consumption (during the idle rotation) can be
restrained as 6.3 watt or less when the spindle rotates at 10000
r.p.m., 8.3 watt or less when it rotates at 12000 r.p.m., and 11.8
watt or less at 15000 r.p.m.
[0076] b) The inner temperature of the housing 11 (during the seek
operation) can be restrained at 47 degree centigrade or less when
the spindle rotates at 10000 r.p.m., at 52 degree centigrade or
less when it rotates at 12000 r.p.m., and at 58 degree centigrade
or less at 15000 r.p.m.
[0077] Finally, the inner temperature of the housing 11 during the
seek operation can be at 60 degree centigrade or less under the
condition that the magnetic disk media are twelve, the magnetic
disk drive is installed in the magnetic disk drive system without
fan.
[0078] The conditions under which the above numerals are obtained
are as follows: the medium is a "2.5 inches" (diameter: 65 mm,
thickness: 0.635 mm), the stack has twelve media, the distance
between media is 1.7 mm, L of fins=32 mm , the thickness t of the
fins=2 mm, a circumferential temperature of the magnetic disk drive
is 25 degree centigrade, the magnetic disk drive system has no
fan.
[0079] The magnetic head 51 and an arm of the actuator 61 receive a
force from a homogeneity air flow that is generated by rotation of
the magnetic disk media. If the force which is received by the
actuator 61 including the magnetic head 51, from the air flow can
be decreased, the torque loss during on-load rotation of the
magnetic disk media 21 further can be decreased, which results in
suppressing the heat generation caused by windage.
[0080] FIG. 2 shows a plan view of an arrangement with basic
elementary parts in the magnetic disk drive shown in FIG. 1.
[0081] A distance B between a rotation center 111 of the magnetic
disk media 21 and a rotation center 121 of the magnetic head 51 can
be reduced comparing with the prior magnetic disk drive shown in
FIG. 3 because the magnetic disk media 21 become smaller in
diameter. Namely, if the distance B of them is set with 40 mm (FIG.
2), a gap on the magnetic head 51, which records or reproduces an
information on or from the magnetic disk media 21, can be arranged
at R=37.5 mm location from the rotation center 121. Incidentally, a
corresponding distance B in the prior magnetic disk drive shown in
FIG. 3, which is defined as a distance between a rotation center
113 of a magnetic disk media 23 and a rotation center 123 of a
magnetic head 53, is 54 mm. Because the magnetic disk media 21
become smaller in diameter than prior media 23, a surrounding space
of the media has a clearance with 15 mm. Therefore, 54 mm-15 mm =39
mm may be adopted as the distance B of FIG. 2. 40 mm.+-.1 mm as the
distance B seems to be realistic value considering a tolerance for
fabrication.
[0082] Further, considering to use existing standard parts of the
actuator for fabricating economic magnetic disk drives, the
distance B of FIG. 2 may be 47.5 mm=the above R+10 mm. A
deterioration in access speed should be compensated by increasing
the torque of the voice coil motor in this case.
[0083] Present invention described above can make an actuator
portion smaller and lighter than the prior actuator 63 including
the magnetic head 53. More specifically, a weight of rotational
portion at the actuator 61 including the magnetic head 51 (FIG. 2)
is about 32 gf (gram-force) to 36 gf, and a moment of inertia of
the rotational portion at the actuator 61 including the magnetic
head 51 is about 5200 gf.square mm to 5800 gf.square mm. In the
prior magnetic disk drive corresponding to FIG. 2, a weight or a
moment of inertia of rotational portion at the prior actuator 63
are 45 gf or 14400 gf.square mm, respectively.
[0084] Applying the present invention, that is, in case the voice
coil motor that gives an output power of 0.2 N.m per one ampere
current in the prior magnetic disk drive of FIG. 3, is used for a
voice coil motor 81 that drives an actuator 61, an average access
time can be decreased to be about 6 milli-seconds in the magnetic
disk drive. Here, the average access time defines an average time
for the magnetic head 51 to be located from a start track to a
destination track which are arranged concentrically on the magnetic
disk media 21. Incidentally, twelve magnetic disk media 21 are used
in this case, the rotational speed of the spindle is 10000 r.p.m.
Inventors of present invention confirmed if the weight of
rotational portion at the actuator 61 is smaller than 36 gf, or if
a torque of the voice coil motor is bigger than 0.12 N.m per one
ampere current, the average access time can be reduced more
smaller. When the weight of rotational portion at the actuator 61
is smaller than 36 gf, and when the torque of the voice coil motor
is 0.12 N.m per one ampere current, the average access time can be
reduced by about 7 milli-seconds.
[0085] An actuator using the voice coil motor that has a torque of
0.12 N.m per one ampere current, gave 6.5 milli-seconds during a
read operation, 7.5 milli-seconds during a write operation in
average access times, respectively (in the third embodiment of
present invention; a weight of rotational portion at the actuator
is 53.0 gf.).
[0086] FIG. 4 shows a size of a magnetic disk medium which has 2.5
inches diameter and 0.381 mm thickness. FIG. 5 shows a size of a
magnetic disk medium which has 1.8 inches diameter and 0.381 mm
thickness. It gives surely above described same effects to exchange
these disk media 24, 25 different in size, for magnetic disk media
21 shown in FIG. 1, and to mount them in the magnetic disk
drive.
[0087] FIG. 6 shows a plan view of the second embodiment of present
invention, a magnetic disk drive which has 41.4 mm or 1.6 inches
nominal height and 3.5 inches form factor size. FIG. 7 shows across
section between A-A portion in FIG. 6.
[0088] The feature of this embodiment is that the magnetic disk
drive arranges fins on all sides of housing 16 as same as shown in
FIG. 1, and that the fins on one side consist of 4 linear fins 16a
arranged at 4 mm interval, each fin has 3 mm thickness at the edge
and 12 mm length, as shown in FIG. 7. Ten magnetic disk medium 26
(FIG. 6), each of which has 65 mm in diameter and 0.8 mm in
thickness, are accommodated at the housing at 1.84 mm interval
(FIG. 7). They are secured to a spindle motor 36 (FIG. 6) that can
drive them at 12000 r.p.m. rotational speed. A maximum temperature
(during seek operation) in the housing 16 is held at 55 degree
centigrade or less and an electric power consumption is 8.7 watts
during an idle rotation in the above case. Incidentally, an
environmental temperature of the magnetic disk drive is 25 degrees
centigrade and there is no fan on a case frame of the magnetic disk
drive system.
[0089] FIG. 8 and FIG. 9 show other shapes of fins. FIG. 8 shows a
cross section between A-A portion in FIG. 6 when fins 16b are
arranged inside the housing 16. FIG. 9 shows a cross section
between A-A portion in FIG. 6 when fins 16c and 16d are arranged
inside and outside the housing 16.
[0090] FIG. 10 and FIG. 11 show the third embodiment of present
invention, a "3.5 inches" magnetic disk drive which has 68 mm
height. This is higher than a normal height of 3.5 inches
standard.
[0091] Fifteen magnetic disk media 22, each of which is 65 mm in
diameter and 0.8 mm in thickness, are stacked to a hub 162 at 2 mm
interval with interjacent disk spacers 142 that is 2 mm in
thickness (FIG. 11). Here, for example, means (a spindle motor)
capable for rotating the magnetic disk media 22 at 12000 r.p.m.
rotational speed, equip its coil 202, stator core 192 and magnet
212 outside the housing in the rotational axis direction of hub
162.
[0092] There are five fins 12a at 5 mm interval on one side of the
housing 12. An edge portion of the fin 12a is 2 mm in thickness. A
length of the fin is 32 mm. PCB (printed circuit board) 152 adopts
SCSI-2 interface(s) and it has terminals for supplying electric
power with voltages, 12 volt and 24 volt. The terminals are
arranged with a clearance, about 7 mm toward the housing 12. Here,
these voltages are exemplifications. If a desirable rotational
speed is obtained, other voltages except 12 volt or 24 volt are
available. Some value in voltage may be adopted, which is decided
by characteristic of a spindle motor.
[0093] Features of this embodiment are as follows:
[0094] 1) this magnetic disk drive adopts a spindle motor located
vertically under the housing 12 in FIG. 11, which is called a
bottom type spindle motor and which rotates inner wheels of
bearings 182a and 182b in order to avoid a leakage of magnetic
fluid sealants and an abrasion of bearings which are caused from a
high speed rotation of the spindle motor and the magnetic disk
media. Consequently, the bottom type spindle motor does not affect
badly to a grease in the bearings and the magnetic fluid sealants
222a, 222b;
[0095] 2) this magnetic disk drive adopts a high voltage of the
electric power supply which gives an enough rush current to spin up
the spindle motor and which compensates a voltage drop in a driving
circuit. The spindle motor can rotate stably in high speed owing to
an enough torque for rotating the magnetic disk media.
[0096] PCB 152 is arranged with a clearance, about 7 mm toward the
housing 12 to restrain a temperature rising of the magnetic disk
drive, which is caused by a heat generation of the PCB.
Consequently, the magnetic disk drive of this embodiment gives 1) 6
giga-bytes in formatted storage capacity, 2) 10 watts electric
power consumption or less, 3) 55 degree centigrade in inner
temperature of the housing 12 (during seek operation) when an
environmental temperature of the magnetic disk drive is 25 degrees
centigrade and there is 2 meters per second of a cooling air flow
caused by fans on a case frame of the magnetic disk drive system.
Incidentally, a transfer rate from the magnetic disk drive to an
upper system is 10 mega-bytes per second or more. Data transfer
rate is expected to be increased more by an optimization of
electric circuits.
[0097] Regardless of this embodiment, if coil 202 and stator core
192 of the spindle motor and all the like driving means there, are
arranged far enough from exterior of the housing 12, and if the
clearance between PCB 152 and the housing 12 is set in 10 mm or
more, the temperature rising of the magnetic disk drive can be
further restrained.
[0098] FIG. 12 is a cross-sectional view that shows an outline of
the internal structure of the magnetic disk drive, fourth
embodiment of the present invention. A housing 11 and a cover 101
are sized in a 3.5 inches form factor which has a nominal height of
41.4 mm. "2.5 inches" magnetic disk media 21 (65 mm in diameter and
0.8 mm in thickness), a spindle motor 41 that rotates these media
in a predetermined rotational speed, a rotary type actuator 61 that
swings around a pivot-bearing 71 for positioning magnetic heads,
and a voice coil motor 81 that drive the actuator, are secured in
the housing 11.
[0099] A securing method of the spindle motor 41 is with a screw or
by a press fit to be secured at one edge of the spindle motor 41 to
the housing 11 that includes the spindle motor 41. The other edge
of the spindle motor 41 is secured at a cover 101 that hermetically
closes the inner space of the housing 11. Magnetic disk medium 21
uses Al (aluminum) or glass for its substrate material.
[0100] Ten magnetic disk media 21 are stacked in a rotational axis
direction at 1.84 mm interval with interjacent disk spacers 141
that is 1.84 mm in thickness. The magnetic disk media 21 are
secured by a disk cramp 31 to the spindle motor 41 that can rotates
in a rotational speed of 12000 r.p.m. The housing 11 casted with an
aluminum alloy has en bloc linear fins 11a stood straight against
111 axis of the rotary center of magnetic disk media 21. The
thickness at the leaf edge t=2.5 mm, the leaf length L=12 mm, a
distance H between leaf edges is 3.5 mm.
[0101] If the housing is casted en bloc, a thickness of the housing
prefers to be kept 1.5 mm or more in order to give a smooth-running
with melting materials during the casting and to uniform mechanical
or physical characteristics of a casted product. The product needs
taper portions in case it is locked inside a casting flask by a
shrinkage that follows a cooling of the product when the product is
separated from the casting flask. The amount of the taper is about
1 degree in angle. If an edge of fin that has 12 mm in length is
1.5 mm in thickness, a basal thickness of the fin is 1.9 mm. If an
edge has 15 mm in length, a basal thickness of the fin is about 2
mm.
[0102] As magnetic disk media 21 becomes smaller in diameter, for
example, as changing "3.5 inches" disk media to "2.5 inches" disk
media in same thickness of 0.8 mm, a weight per one disk medium
reduces by about 54%. In other thickness of 0.635 mm, as changing
to "2.5 inches" disk media, the weight per one disk medium reduces
by about 64%. Therefor, a gross weight that the spindle motor
rotates can be reduced, which brings a high characteristic at a
spin-up operation, and which also effects a reduction of electric
current (electric energy consumption) during an idle rotation.
[0103] If magnetic disk media are changed from "3.5 inches" to "2.5
inches", for example, a maximum marginal velocity when the "3.5
inches" disk media rotate at 10000 r.p.m. equals to a maximum
marginal velocity when the "2.5 inches" disk media rotate at 14600
r.p.m. Therefore, when recording or reproducing an dedicated
information to or from the magnetic disk media 21 by a magnetic
head 51 via a magnetic flux, if a signal processing ability is same
as in the past or more, faster rotation of the media can be
executed without a reduction of recording density in longitudinal
direction along a track that is located concentrically on the
magnetic disk media 21.
[0104] When magnetic disk media 21 rotate, they receive a
frictional resistance by a viscosity of air that surrounds the
magnetic disk media 21. A transition boundary where an air flow
along a surface of the magnetic disk media becomes from a laminar
flow to a turbulent flow is about 15000 r.p.m. when the magnetic
disk media 21 is "3.5 inches" disk, and about 30000 r.p.m. when the
media is "2.5 inches" disk.
[0105] When magnetic disk media 21 are changed from "3.5 inches" to
"2.5 inches", the transition boundary is big enough against the
number of rotation limits of the spindle motor 41. Because an
torque loss during on-load rotation, which is caused from the
frictional resistance, becomes bigger square or cubicly
proportional to a diameter of the magnetic disk media, if the
spindle rotates the media in a same speed, the torque loss of "2.5
inches" disk media corresponds to about 50%.about.34% of that of
"3.5 inches" disk media. Therefore, when the spindle motor 41
rotates in a predetermined idle speed, the current (consumption
power) becomes smaller, and a heat generation caused by windage can
be restrained. Fins 11a are made at plural portions of the housing
11, which have an effect that increases a surface area of the
housing 11 and that makes a heat-penetration flow good. The tips of
fins 11a become closer to the temperature of the external air of
housing 11. The rotation of spindle motor 41 and the flutter of
actuator 61 driven by the system generate a heat, which rises an
internal temperature of the magnetic disk drive. The fins 11a
reduce this temperature increase.
[0106] The thickness of the fin at the edge or tip may be 1.5 mm or
more, considering its easier fabrication. If a length of the fin is
elongated, a surface area of the fin becomes larger. A temperature
of an air that flows along the fin increase because a heat from the
fin and a heat by a viscosity resistance are conducted to the air.
Therefore the fin should be divided into plural portions. FIG. 13
shows shapes of fins divided into three d 11b, 11c, 11d in a depth
direction of the magnetic disk drive.
[0107] Here, a height direction is defined to be called a thickness
direction if the magnetic disk drive stands as a rotational axis of
its hub is vertical. A longer side is defined to be called a depth
direction and a shorter side, a width direction if the magnetic
disk drive is seen from a bird's-eye view. These divided fins are
arranged like steps of stairs, which change in position in the
thickness direction.
[0108] The fins are located in a space that is surrounded by a base
(housing) 11, a mounting portion 11g which mounts a cover 101 and a
mounting portion 11h which mounts a circuit board. This space also
forms a pass for an air flow 300 shown in FIG. 14.
[0109] Fins 11a, 11b, 11c and 11d have a function that can enhance
a cooling efficiency of the magnetic disk drive about air flows
those are shown by arrow marks 300, 301 and 302 in FIG. 14 and FIG.
18. The portion of the fins, which encounters with the air flow is
cooled best in the air flow. The cooling efficiency decreases for
the air's going downstream from the encounter portion owing to a
development of a boundary layer. Therefore the best efficiency
about the air flow is given by a bossy fin.
[0110] On the other hand, a radiation area decides a cooling
efficient if there is no air flow. Therefore, a strap shape fin is
effective in this case. Further, if it is considered to assemble or
to cast en bloc with the housing 11 and fin 11a etc. of the
magnetic disk drive, practical shapes of the fins those have good
cooling efficiency are, as shown in present embodiments, plural
sets of short strap shape fins, which are arranged surrounding the
magnetic disk drive.
[0111] It is desirable for fins and air flow to encounter or to
collide each other as possible as they can. And it is necessary to
keep an energy loss of the air flow small, to maintain the
air-current speed and to hold the pass open. It is also a desirable
configuration of the fin to have smooth roundness at the corners
(air-collision portion) that directly encounter the air flow in
order to keep the loss of air flow small and to maintain the
cooling efficiency high when the air flow collides with the
corners.
[0112] Therefore in present invention that takes the above
phenomenon into consideration, plural strap-shape fins are arranged
changing in position in the thickness direction. That is, FIG. 14
shows the air flow 300 comes from left hand. Some air flow shown as
short arrow 300a collides with a round portion 11b' of leading edge
of the fin one after another, cooling the leading edge
preferentially and going through to right hand of FIG. 14.
[0113] Passes shown as long arrows 300b are arranged for some other
air flow besides the collision air in order to keep the air-current
speed. Consequently, among width-direction fins 11a and
depth-direction fins 11b, 11c and 11d (FIG. 13), neighbor sets of
fins differ in height (location in the thickness direction) and are
arranged changing in their heights one after another.
[0114] FIG. 15 shows one set of fin 11a in the width direction and
the row is one column (set) because a flask is used to form the
fins by en bloc casting. So called sliding cores those separate in
bidirectionally, right and left respectively, form fins in the
depth direction and in the width direction. Right and left sliding
cores meet at a center portion (11f) of fins in the width direction
and form the fins 11a. In separation, each of the sliding cores
goes along the arrow 400, 401 shown in FIG. 15, respectively, and
the product is released.
[0115] Fins 11a in the width direction become a single row fins
when the roundness of their corners are formed by casting. At most
two row fins (FIG. 16) changing in their heights can be fabricated
when the roundness of their corners are worked afterwards without
casting. A parting face (separation face) of the sliding cores
defines a boundary between the two row fins. The fins in present
invention can reserve about 70,000 square milli-meter or more as
the surface area of the magnetic disk drive.
[0116] Further explanation about the flask is complemented using
FIG. 15. A flask for casting the base 11 consists of a normal main
flasks those separate up-and-down direction of FIG. 15 and sliding
cores those form fins 11a, 11b. The sliding cores slide in
predetermined directions accompanying with a separating operation
of the normal main flasks. The sliding cores may consist of three
members or more in order to form fins in a predetermined shape. On
the other hand, the sliding cores may be two members according to a
heat generation of the magnetic disk drive or to keep a freedom in
fabrication of the mounting portion that mounts a circuit
board.
[0117] FIG. 18 shows a varied embodiment which is increased in
height of mounting portion 11g that mounts cover 101 to base
(housing 11), satisfying 3.5 inches form factor size. In this
embodiment:
[0118] a) an electric power consumption (during an idle rotation
loaded 10 disk media can be restrained as 5.5 watts at 10,000
r.p.m. rotational speed, and 7.0 watts at 12,000 r.p.m. rotational
speed;
[0119] b) a temperature rising (during following operation, an
environmental temperature is 32 degrees centigrade) can be
restrained at 40 degrees centigrade or less at 12,000 r.p.m.
rotational speed. Without a cooling air flow, it can be restrained
at 46 degrees centigrade or less at 10,000 r.p.m. rotational speed,
at 52 degrees centigrade or less at 12,000 r.p.m. rotational
speed.
[0120] The numerals above described are obtained under the
condition that ten "2.5 inches" media (65 mm in diameter, 0.635 mm
in thickness) are installed at 1.84 mm interval in a magnetic disk
drive with fins those are 12 mm in length and 2 mm in thickness.
And that an environmental temperature of the magnetic disk drive is
32 degrees centigrade and there is no cooling air flow caused by
fans on a case frame of the magnetic disk drive system.
[0121] The magnetic head 51 and an arm of the actuator 61 receive a
force from a homogeneity air flow that is generated by rotation of
the magnetic disk media. If the force which is received by the
actuator 61 including the magnetic head 51, from the air flow can
be decreased, the torque loss during on-load rotation of the
magnetic disk media 21 further can be decreased, which results in
suppressing the heat generation caused by windage.
[0122] FIG. 17 shows fifth embodiment of the present invention.
Namely, a cover mounting portion 11g is extended upwards to be 41.4
mm, air passes are enlarged and numbers of fins are increased.
[0123] FIG. 19 shows sixth embodiment of the present invention, 68
mm height "3.5 inches" magnetic disk drive, which has a larger
height than normal "3.5 inches" standard. Fifteen magnetic disk
media 22 are stacked on a hub 162 at 2 mm interval with interjacent
disk spacers 142 (FIG. 19) that is 2 mm in thickness. Here, for
example, means (a spindle motor) capable for rotating the magnetic
disk media 22 at 12000 r.p.m. rotational speed, equip its coil 202,
stator core 192 and magnet 212 outside the housing in the
rotational axis direction of hub 162. There are five fins 12a at 6
mm interval on one side of the housing 12. An edge portion of the
fin 12a is 2 mm in thickness. A length of the fin is 32 mm.
[0124] PCB (printed circuit board) 152 adopts SCSI-2 interface(s)
and it has terminals for supplying electric power with voltages, 12
volt and 5 volt. Features of this embodiment are as follows.
[0125] 1) this magnetic disk drive adopts a spindle motor located
vertically under the housing 12 in FIG. 19, which is called a
bottom type spindle motor and which rotates inner wheels of
bearings 182a and 182b in order to avoid a leakage of magnetic
fluid sealants and an abrasion of bearings which are caused from a
high speed rotation of the spindle motor and the magnetic disk
media. Consequently, the bottom type spindle motor does not affect
badly to a grease in the bearings and the magnetic fluid sealants
222a, 222b;
[0126] 2) this magnetic disk drive adopts a high voltage of the
electric power supply which gives an enough rush current to spin up
the spindle motor and which compensates a voltage drop in a driving
circuit. The spindle motor can rotate stably in high speed owing to
an enough torque for rotating the magnetic disk media.
[0127] PCB 152 is arranged with a clearance, about 7 mm toward the
housing 12 to restrain a temperature rising of the magnetic disk
drive, which is caused by a heat generation of the PCB 152.
[0128] Consequently, the magnetic disk drive of this embodiment
gives 1) 15 giga-bytes in formatted storage capacity, 2) 14 watts
electric power consumption or less, 3) a transfer rate from the
magnetic disk drive to an upper system is 10 mega-bytes per second
or more.
[0129] Data transfer rate is expected to be increased more by an
optimization of electric circuits. Regardless of this embodiment,
if coil 202 and stator core 192 of the spindle motor and all the
like driving means are arranged far enough from exterior of the
housing 12, and if the clearance between PCB 152 and the housing 12
is set in 10 mm or more, the temperature rising of the magnetic
disk drive can be further restrained.
[0130] FIG. 20 shows seventh embodiment of the present invention,
that is, a magnetic disk drive mounted directly with a cooling fan
400. The cooling fan 400 is driven by a circuit board (PCB, printed
circuit board). As shown in Figure, the cooling fan 400 is arranged
in order to make an air flow through above described air passes,
which are surrounded by a cover mounting portion 11g and circuit
board mounting portion 11h. The direction of the air flow by the
cooling fan 400 may be variable.
[0131] FIG. 21 shows the eighth embodiment of present
invention.
[0132] In this magnetic disk drive, a magnetic disk head 56 is so
correctly positioned that positioning servo signals are written on
magnetic disk media 21 before the magnetic disk drive is
shipped.
[0133] The writing of the servo signals are performed after a base
(housing 11), a cover 101, disk media 21, spindle motor 41 or the
like of structural parts are assembled. It needs a reference signal
to write the servo signals. The magnetic disk drive needs a hole
11e through which the reference signal is provided. The hole 11e
needs to be arranged on a side of the base (housing 11). So, it is
necessary for forming the hole 11e to use sliding cores in casting
flask. The sliding cores can make the fins 11a and the hole 11e on
a same face, which makes the housing 11 formation (casting fins 11a
etc. en bloc) more easy.
[0134] FIG. 22 shows the ninth embodiment of present invention.
[0135] Fins 11a in the width direction are extended further. A
portion of them reaches side faces in the depth direction shown in
FIG. 23 and FIG. 24. In this embodiment that increase a surface
area, dividing casting flasks (sliding cores) into right and left
directions can form fins 11a.
[0136] FIG. 25 shows a schematic of a magnetic disk drive system or
a disk array system, which connects a plurality of magnetic disk
drive 230 that is explained in FIG. 1, FIG. 6, FIG. 10 and FIG.
11.
[0137] The magnetic disk drive system sets a case 240 that mounts
or secures plural magnetic disk drives 230, and a control unit 250
within the case. The control unit 250 couples electrically the
plural magnetic disk drives 230 and controls them. Further the
magnetic disk drive system sets fans 260 that refrigerate the
control unit 250 and the plural magnetic disk drives 230. The fan
260 can be omitted if temperature circumstances surrounding the
system at a installation place are favorable or if a number of
magnetic disk drives mounted on the system is small enough. The
fans 260 may be arranged for cooling plural magnetic disk drives
mainly. Special fans 260 may be arranged for the control unit
250.
[0138] Control unit 250 mainly receives data from or transmits data
to plural magnetic disk drives, the magnetic disk drive system or
the upper system that uses the magnetic disk drives or the magnetic
disk drive system, and mainly administer control information.
[0139] When an air flow by the fan 260 is 2 meter per second, a
maximum temperature (during seek operation) in the housing of the
magnetic disk drive 230 is held at 55 degree centigrade or less.
Here, parameters around this magnetic disk drive are as follows:
magnetic disk media have a 65 mm in diameter for "2.5 inches" size
and a 0.8 mm in thickness; an interval or a distance of the media
is 2.0 mm; a length of fins arranged around the media is 32 mm and
a thickness of the fins is 2 mm, a number of leaves in magnetic
disk media is 15; a rotational speed of a spindle that rotates the
media is 12000 r.p.m.; an electric power consumption is 10 watts
during an idle rotation in the above magnetic disk drive; a
distance between a hub center and an actuator center is 43.2 mm;
and a weight of rotational portion at the actuator is 53.0 gf.
[0140] FIG. 26 and FIG. 27 show the tenth embodiment of present
invention, 1.6 inches height "3.5 inches" magnetic disk drive.
[0141] A housing 2 is 3.5 inches form factor size which has a
nominal height of 25.4 mm. The housing mounts magnetic disk media
4, a spindle motor (not shown) rotating the media in a
predetermined speed, a swing type actuator 13 positioning a
magnetic head 11 around a pivot bearing 15, and voice coil motor
that is a driving means for the actuator.
[0142] There are two securing embodiments: one of a securing method
of the spindle motor is with a screw or by a press fit to be
secured at one edge of the spindle motor to the housing 2 that
includes the spindle motor; the other of a securing method of the
spindle motor is with a screw or by a press fit to be secured at
one edge of the spindle motor to the housing 2 that includes the
spindle motor and the other edge of the spindle motor is secured at
a cover that hermetically closes the inner space of the housing 2.
Axes for the spindle motor and the actuator may be secured by glues
or adhesives to the housing. This securing method can bring more
economical magnetic disk drives.
[0143] Features in this embodiment are: magnetic disk media 4 are
made with Al (aluminum) or glass and they are "2.5 inches" in
diameter. The six magnetic disk media 4, each of which has 0.635 mm
in thickness, are mounted axially with interjacent disk spacers
those are each 1.7 mm in thickness. Magnetic disk media 4 are
secured stably by a disk cramp 8 and a screw 19. There is a space
around the magnetic disk media 4. The space makes better a
radiation characteristic in the housing 2, and the space gives
freedom for selecting parts used in the housing.
[0144] A distance between a rotation center 21' of the magnetic
disk 4 and a rotary center 23' of the magnetic head 11 is set up
for 40 mm. The actuator 13 is secured via the pivot bearing 15 to
the housing 2. The distance can be set at most 47.5 mm (=R below
described +10 mm) for more economical structures of the magnetic
disk drives, if existing actuator parts are used and if the torque
of the voice coil motor is increased.
[0145] If `2.5` inches magnetic disk media of 0.8 mm in thickness
are used in stead of `3.5 inches` magnetic disk media of same
thickness, the weight decreases by about 54% per one medium. If
`2.5` inches magnetic disk media of 0.635 mm in thickness are used
in stead of `3.5 inches` magnetic disk media of 0.8 mm in
thickness, the weight decreases by about 64% per one medium. Owing
to a decrease in total weight of the media those are rotated by the
spindle, there are effects on a high characteristic of a spin-up
operation by the spindle motor, and also on a reduction of electric
current (electric energy consumption) during an idle rotation.
[0146] FIG. 27 shows basic inner structure of present invention (in
plan view).
[0147] The distance L between the rotation center 21' of the
magnetic disk 4 and the rotary center 23' of the magnetic head 11
can be set shorter than that of prior magnetic disk drives because
the smaller magnetic disk media 4 are used than usual. A gap 25' of
the magnetic head 11 that records or reproduces information to or
from the magnetic disk media 4, locates 37.5 mm (=R) from the
rotary center 23'.
[0148] Thus in this embodiment, the parts can be freely arranged in
the housing. If a performance (mainly storage capacity) be
sacrificed, inexpensive parts can be adopted. So, there is a effect
on fabrication of magnetic disk drives or magnetic disk drive
systems, which put a high speed accessing function and an
inexpensive device price into practice.
[0149] Because the present invention adopts using smaller magnetic
disk media in form factor size than usual in a normal form factor
size magnetic disk drive housing, or arranging fins (unlevel,
washboard or jaggy portion) around the housing, prior problems
those are generated in a high speed rotational technique can be
resolved. And the magnetic disk drive or systems using thereof can
be realized, which spends less electric power and gives less heat
generation than prior magnetic disk drive, and which can indicate a
high access performance with a high storage capacity.
[0150] When the magnetic disk drive of present invention is used
for a disk array system or other magnetic disk drive systems, it
can replace prior magnetic disk drive without adding a special
cooling mechanism to the prior systems. There is an effect on
easily realizing to perform a high speed operation and a high
function, and to increase a storage capacity.
[0151] Having described a preferred embodiment of the invention
with reference to the accompanying drawings, it is to be understood
that the invention is not limited to the embodiments and that
various changes and modifications could be effected therein by one
skilled in the art without departing from the spirit or scope of
the invention as defined in the appended claims.
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