U.S. patent application number 15/391746 was filed with the patent office on 2017-10-12 for protection of disk drive from external electromagnetic waves.
The applicant listed for this patent is KABUSHIKI KAISHA TOSHIBA. Invention is credited to Toshihiro TSUJIMURA, Nobuyoshi YAMASAKI.
Application Number | 20170294215 15/391746 |
Document ID | / |
Family ID | 59999573 |
Filed Date | 2017-10-12 |
United States Patent
Application |
20170294215 |
Kind Code |
A1 |
YAMASAKI; Nobuyoshi ; et
al. |
October 12, 2017 |
PROTECTION OF DISK DRIVE FROM EXTERNAL ELECTROMAGNETIC WAVES
Abstract
A disk drive includes a metal base that has a rectangular bottom
wall and side walls formed on each side of the rectangular bottom
wall, the side walls including a first side wall on a shorter side,
a metal cover that is fixed to the metal base with a plurality of
metal screws, including two screws disposed at opposite ends of the
side wall, a gap being formed between an upper end of the first
side wall and the metal cover, a magnetic disk disposed on the
metal base, at a position offset from a center of the metal base in
a longitudinal direction towards the first side wall, and a head.
The first side wall and the metal cover are electrically connected
at an intermediate position of the first side wall between said
opposite ends of the first side wall.
Inventors: |
YAMASAKI; Nobuyoshi;
(Kamakura Kanagawa, JP) ; TSUJIMURA; Toshihiro;
(Ota Tokyo, JP) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
KABUSHIKI KAISHA TOSHIBA |
Tokyo |
|
JP |
|
|
Family ID: |
59999573 |
Appl. No.: |
15/391746 |
Filed: |
December 27, 2016 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
62319683 |
Apr 7, 2016 |
|
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|
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
G11B 33/027 20130101;
G11B 25/043 20130101; G11B 33/1466 20130101; G11B 33/1493
20130101 |
International
Class: |
G11B 33/14 20060101
G11B033/14; G11B 33/02 20060101 G11B033/02 |
Claims
1. A disk drive comprising: a metal base that has a rectangular
bottom wall and side walls formed on each side of the rectangular
bottom wall, the side walls including a first side wall on a
shorter side; a metal cover that is fixed to the metal base with a
plurality of metal screws, including two screws disposed at
opposite ends of the first side wall, a gap being formed between an
upper end of the first side wall and the metal cover; a magnetic
disk disposed on the metal base, at a position offset from a center
of the metal base in a longitudinal direction towards the first
side wall; and a head configured to write data to and read data
from the magnetic disk, wherein the first side wall and the metal
cover are electrically connected at an intermediate position of the
first side wall between said opposite ends of the first side
wall.
2. The disk drive according to claim 1, further comprising: a
conductive member attached to the metal cover and the intermediate
position of the first side wall for electrical connection
therebetween.
3. The disk drive according to claim 2, wherein the conductive
member is formed of copper.
4. The disk drive according to claim 1, further comprising: a
gasket disposed between a top surface of the first side wall and a
bottom surface of the metal cover, the gap being formed
corresponding to the gasket.
5. The disk drive according to claim 1, wherein the metal cover
includes a protrusion that protrudes towards the first side wall at
the intermediate position, and the protrusion is in contact with
the first side wall.
6. The disk drive according to claim 5, wherein the first side wall
includes a recessed portion in which the protrusion fits.
7. The disk drive according to claim 5, further comprising: a
gasket disposed between a top surface of the first side wall and a
bottom surface of the metal cover, the gap being formed
corresponding to the gasket, wherein the protrusion of the metal
cover is located outside a region of the metal cover that is in
contact with the gasket.
8. The disk drive according to claim 1, further comprising: a
connector that is disposed for connection with an external device
along the first side wall.
9. The disk drive according to claim 1, wherein at least two loop
antennas are formed in the gap.
10. A disk drive comprising: a metal base that has a rectangular
bottom wall and side walls formed on each side of the rectangular
bottom wall, the side walls including a first side wall on a
shorter side; a metal cover above the metal base, a gap being
formed between the first side wall and the metal cover; a magnetic
disk disposed on the metal base, at a position offset from a center
of the metal base in a longitudinal direction towards the first
side wall; and a head configured to write data to and read data
from the magnetic disk, wherein the metal cover and the first side
wall are electrically connected at first, second, and third
positions of the first side wall, the second position being between
the first and third positions, a first loop antenna is formed in a
part of the gap between the first position and the second position
of the side wall, and a second loop antenna is formed in another
part of the gap between the second position and the third position
of the side wall.
11. The disk drive according to claim 10, further comprising: a
conductive member attached to the metal cover and the first side
wall at the second position.
12. The disk drive according to claim 11, wherein the conductive
member is formed of copper.
13. The disk drive according to claim 10, further comprising: a
gasket disposed between a top surface of the first side wall and a
bottom surface of the metal cover, the gap being formed
corresponding to the gasket.
14. The disk drive according to claim 10, wherein the metal cover
includes a protrusion that protrudes towards the first side wall at
the second position, and the protrusion is in contact with the
first side wall.
15. The disk drive according to claim 14, wherein the first side
wall includes a recessed portion in which the protrusion fits.
16. The disk drive according to claim 14, further comprising: a
gasket disposed between a top surface of the first side wall and a
bottom surface of the metal cover, the gap being formed
corresponding to the gasket, wherein the protrusion of the metal
cover is located outside a region of the metal cover that is in
contact with the gasket.
17. The disk drive according to claim 10, further comprising: a
connector that is disposed for connection with an external device
along the first side wall.
18. A method for protecting a disk drive from external
electromagnetic waves, comprising: assembling a disk drive
including: a metal base that has a rectangular bottom wall and side
walls formed on each side of the rectangular bottom wall, the side
walls including a first side wall on a shorter side; a metal cover
that is fixed to the metal base with a plurality of metal screws,
including two screws disposed at opposite ends of the first side
wall, a gap being formed between an upper end of the first side
wall and the metal cover; a magnetic disk disposed on the metal
base, at a position offset from a center of the metal base in a
longitudinal direction towards the first side wall; and a head
configured to write data to and read data from the magnetic disk;
and attaching a conductive member to the metal cover and the first
side wall, at an intermediate position of the first side wall
between said opposite ends of the first side wall.
19. The method according to claim 18, wherein the disk drive
further includes a gasket disposed between a top surface of the
first side wall and a bottom surface of the metal cover, the gap
being formed corresponding to the gasket.
20. The method according to claim 18, wherein the disk drive
further includes a connector that is disposed for connection with
an external device along the first side wall.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application claims the benefit of U.S. Provisional
Application No. 62/319,683, filed Apr. 7, 2016, the entire contents
of which are incorporated herein by reference.
FIELD
[0002] Embodiments described herein relate to a disk drive, in
particular, protection of a disk drive from external
electromagnetic waves.
BACKGROUND
[0003] A hard disk drive (HDD) typically includes a rectangular
housing, a recording medium (disk) disposed in the housing, and a
magnetic head which reads/writes data from/to the recording medium.
Further, the housing typically includes a rectangular base and a
top cover formed in the shape of a plate and screwed to the base.
When such an HDD is used in an external device, when an external
magnetic field such as electromagnetic waves is applied from the
external device to the housing of the HDD, noise may negatively
affect operation of the HDD, i.e., data reading/writing by the
magnetic head on the disk. It is therefore preferable that the HDD
has capability to inhibit magnetic field resonance occurring
because of an external magnetic field, and prevent the magnetic
field resonance from interfering with its operation.
BRIEF DESCRIPTION OF THE DRAWINGS
[0004] FIG. 1 is a perspective view of a hard disk drive (HDD)
according to a first embodiment.
[0005] FIG. 2 is a perspective exploded view of the HDD.
[0006] FIG. 3 is a plan view of an inner structure of the HDD.
[0007] FIG. 4 is a side view of the HDD on a short side
thereof.
[0008] FIG. 5 schematically illustrates space formed between a top
cover and a short side wall of the base of the HDD.
[0009] FIG. 6 illustrates an electromagnetic-wave reflection
characteristic of the HDD when electromagnetic waves (magnetic
field) are applied to the HDD from the outside thereof.
[0010] FIG. 7 is a perspective view of a hard disk drive (HDD)
according to a second embodiment.
[0011] FIG. 8 is a perspective exploded view of the HDD according
to the second embodiment.
[0012] FIG. 9 is a side view of the HDD on a short side
thereof.
DETAILED DESCRIPTION
[0013] Various embodiments will be described hereinafter with
reference to the accompanying drawings.
[0014] In general, according to an embodiment, a disk drive
includes a metal base that has a rectangular bottom wall and side
walls formed on each side of the rectangular bottom wall, the side
walls including a first side wall on a shorter side, a metal cover
that is fixed to the metal base with a plurality of metal screws,
including two screws disposed at opposite ends of the side wall, a
gap being formed between an upper end of the first side wall and
the metal cover, a magnetic disk disposed on the metal base, at a
position offset from a center of the metal base in a longitudinal
direction towards the first side wall, and a head configured to
write data to and read data from the magnetic disk. The first side
wall and the metal cover are electrically connected at an
intermediate position of the first side wall between said opposite
ends of the first side wall.
First Embodiment
[0015] A hard disk drive (HDD) according to a first embodiment will
be described in detail.
[0016] FIG. 1 is a perspective view of the HDD according to the
first embodiment, FIG. 2 is a perspective exploded view of the HDD,
and FIG. 3 is a plan view of an inner structure of the HDD.
[0017] As shown in FIGS. 1 to 3, the HDD includes a housing 10. The
housing 10 includes a base 12 formed in a shape of a rectangular
box which is open on its upper side, and a top cover 14 formed in a
shape of a rectangular plate. The top cover 14 is secured to the
base 12 by a plurality of screws 17 and closes an upper opening of
the base 12. The base 12 includes a rectangular bottom wall 12a and
side walls 12b provided along peripheral edges of the bottom wall
12a, and those walls 12a, 12b are formed of a metallic material
such as aluminum or stainless and formed integrally with each
other. The side walls 12b of the base 12 include a pair of long
side walls 13a located opposite to each other and first and second
short side walls 13b and 13c located opposite to each other.
[0018] The top cover 14 has substantially the same size as the
bottom wall 12a of the base 12 and is formed by press-forming, for
example, a stainless plate. At four corner portions of the top
cover 14 and substantially center portions of long sides of the top
cover 14, through holes 18 are formed (See FIG. 2). The top cover
14 is fastened to the side walls 12b of the base 12 by the screws
17, which are inserted in the through holes 18. That is, the top
cover 14 is fastened to the base 12 by the screws 17 at both ends
of the first short side wall 13b, both ends of the second short
side wall 13c, and substantially central portions of the long side
walls 13a.
[0019] A gasket 20 that is formed in the shape of a frame is
sandwiched between an upper end surface of the side walls 12b of
the base 12 and an outer peripheral edge portion of the top cover
14. The gasket 20 is used to seal space between the base 12 and the
top cover 14 in an airtight manner.
[0020] As shown in FIGS. 2 and 3, in the housing 10, for example,
three magnetic disks 16 are disposed as recording mediums, and a
spindle motor 23 is disposed as a drive unit which supports and
rotates the magnetic disks 16. The spindle motor 23 is disposed on
the bottom wall 12a. Each of the magnetic disks 16 has, for
example, a diameter of 88.9 mm (3.5 inches), and includes magnetic
recording layers (magnetic recording surfaces) on both surfaces
(upper and lower surfaces) thereof. The magnetic disks 16 are
engaged coaxially with a hub (not shown) of the spindle motor 23,
and clamped by a clamp spring 27 to be fixed to the hub. Thereby,
the magnetic disks 16 are supported in such a way as to be located
in parallel with the bottom wall 12a of the base 12. The magnetic
disks 16 are rotated at a predetermined speed by the spindle motor
23. Also, within the housing 10, the magnetic disks 16 are
displaced from a center portion of the base 12 in the longitudinal
direction thereof, toward the short side wall 13b. Thereby, the
magnetic disks 16 are located adjacent to the short side wall 13b,
i.e., away from the short side wall 13c.
[0021] In the housing 10, a plurality of magnetic heads 19 each of
which corresponds to one of the magnetic disks 16, and a carriage
assembly 22 are disposed. Each of the magnetic heads 19
reads/writes data from/to the corresponding magnetic disk 16, and
the carriage assembly 22 supports the magnetic heads in such a way
as to allow the magnetic heads 19 to be movable relative to the
magnetic disks 16. Furthermore, in the housing 10, a voice coil
motor (hereinafter referred to as VCM) 24, a ramp load mechanism
25, a latch mechanism 26, and a flexible printed circuit (FPC)
board unit 21 are disposed. The VCM 24 rotates and positions the
carriage assembly 22. The ramp load mechanism 25 holds the magnetic
heads 19 in an unload position located away from the magnetic disks
16, when the magnetic heads 19 are moved to outermost
circumferential portions of the magnetic disks 16. The latch
mechanism 26 holds the carriage assembly 22 in a retreat position
when an impact or the like is applied to the HDD. On the FPC unit
21, electronic components such as a conversion connector are
mounted. The carriage assembly 22, the VCM 24, the ramp load
mechanism 25, the latch mechanism 26, and the FPC unit 21 are
disposed in space between the magnetic disks 16 and the short side
wall 13c of the base 12.
[0022] As shown in FIGS. 1 and 2, the HDD includes a printed
circuit board (control circuit board) 30. The printed circuit board
30 is screwed to an outer surface (bottom surface) of the bottom
wall 12a of the base 12, and located opposite an inner surface of
the bottom wall 12a of the base 12 that faces the disks 16, with a
slight gap between them. Between the outer surface of the bottom
wall 12a of the base 12 and the printed circuit board 30, an
insulating sheet (film) (not shown) is disposed as an insulating
member.
[0023] On an inner surface of the printed circuit board 30 (i.e., a
surface facing the base 12), a semiconductor chip and semiconductor
elements 34 which form a control unit, and electronic components
such as a rotation vibration sensor (or acceleration sensor) 35 are
mounted. At one edge of the printed circuit board 30 in the
longitudinal direction thereof, a connector 36 is disposed, and at
the other edge of the printed circuit board 30 in the longitudinal
direction, an interface connector 38 connectable to an external
device is disposed. At a center portion of the printed circuit
board 30 in the longitudinal direction thereof, a connection
terminal 37 for the spindle motor 23 is disposed.
[0024] When the printed circuit board 30 is attached to the base
12, the connector 36 is connected to the conversion connector
mounted on the FPC unit 21. The interface connector 38 is located
close to the first short side wall 13b of the housing 10 and a
conductive portion 40. For example, a rectangular recess portion is
formed in the first short side wall 13b on a side closer to the
bottom wall 12a, and an interface connector 38 fits in the recess
portion. The connecter terminal 37 is connected to a connection
terminal connected to the spindle motor 23. The control unit of the
printed circuit board 30 controls operations of the VCM 24 and
magnetic heads 19 using the FPC unit 21, and controls an operation
of the spindle motor 23 through the connection terminal 37.
[0025] FIG. 4 is a side view of the HDD, where the short side wall
13b is located. As shown in FIGS. 1 and 4, the HDD includes the
conductive portion 40, which electrically connects the first short
side wall 13b of the base 12 and the top cover 14. In the first
embodiment, the conductive portion 40 is formed of a tape having
electrical conductivity such as a copper tape 41. The copper tape
41 is stuck to an outer surface of the first short side wall 13b
and an outer surface of the top cover 14 and electrically connects
the first short side wall 13b and the top cover 14. The copper tape
41 is stuck to an intermediate portion of the first short side wall
13b in the longitudinal direction thereof, i.e., an area between
screwed portions of both ends of the first short side wall 13b, and
electrically connects the intermediate portion to the top cover
14.
[0026] As shown in FIG. 4, in the first embodiment, d1=d2 is
satisfied, where d1 and d2 are distances between the screwed
portions (conducting positions) of the first short side wall 13b
and the copper tape 41, respectively. In the first embodiment, d1
and d2 are set to 70 mm, so that a natural frequency of the first
short side wall 13b becomes 2 GHz or more. If the natural frequency
of the first short side wall 13b is less than 2 GHz, noise may
enter the HDD from the outside thereof and cause the HDD to
malfunction. This is undesirable.
[0027] In the HDD according to the first embodiment, a reference
value of the natural frequency is set to 2 GHz for the following
reason. It is preferable that an electronic device such as an HDD
has a high electromagnetic susceptibility (EMS) to inhibit magnetic
field resonance that can be caused by an external magnetic field,
and prevent the magnetic field resonance from interfering with its
operation. In a test for checking EMS, for example, an E-field test
(a test based on radio standards), a range (a value less than
reference value) of the natural frequency, in which EMS decreases,
is set in each of devices. If the natural frequency of a device is
less than the above reference value, i.e., it is within the above
range, noise that enters the device is more likely cause
malfunction of the device. In order to obtain a high EMS, it is
necessary that the natural frequency of the device is greater than
or equal to the reference value. In view of this point, in the HDD
according to the first embodiment, the reference value of the
natural frequency is assumed to be, for example, 2 GHz, and the
distances d1 and d2 are set to 70 mm so that the natural frequency
of the first short side wall 13b becomes greater than or equal to
the reference value, i.e., 2 GHz.
[0028] Next, influence of a natural frequency of the first short
side wall 13b on the HDD, i.e., relationship between distances d1
and d2 and the natural frequency, will be described.
[0029] FIG. 5 schematically shows the first short side wall 13b and
the top cover 14 of the HDD. As shown in FIG. 5, in the outside of
the gasket 20, a slight gap (opening region) is present between the
upper end surface of the first short side wall 13b and a lower
surface of the top cover 14. Because of gaps between the screws 17
and the conductive portion 40 (conductive tape 41), peripherals of
the gaps along the top cover 14, the screws 17, the first short
side wall 13b, and the conductive tape 41 form loops, and each of
the loops functions as a loop antenna. The length (loop length) of
a circuit of each of the loop antennas is formed to correspond to
the natural frequency of the first short side wall 13b, and be
coincident with wavelength .lamda. of electromagnetic waves
generated in the opening region when electromagnetic waves are
applied from the outside of the HDD.
[0030] Where the wavelength is .lamda.(m)=C (the velocity of
light)/f (Hz), the velocity of light C is 299,792,458 m/s, and f
(Hz) is 2.times.10.sup.9 Hz (2 GHz), the wavelength .lamda. is
approximately 140 mm. The loop length is formed to be coincident
with the wavelength .lamda.. Thus, each of the lengths (distances)
d1 and d2 of the gaps is 70 mm or less.
[0031] The relationship between the wavelength .lamda. and the
natural frequency (Hz) satisfies the wavelength=propagation
velocity/frequency, and in vacuum, electromagnetic wave=speed of
light. However, in air, electromagnetic waves become slightly
slower; in the other mediums, they become further slower, and
electromagnetic wave=speed of light/ (.epsilon.), where .epsilon.
is a relative permittivity of the medium.
[0032] On the other hand, if the conductive portion 40 or the
conductive tape 41 is absent, the length of the peripherals of the
gaps between the upper end surface of the short side wall 13b and
the top cover 14, i.e., the loop antenna length or the loop length,
would be approximately 200 mm, and frequency=propagation
velocity/wavelength=1.5 GHz. That is, the natural frequency of the
above gap would become smaller than the reference value (2 GHz).
This is undesirable.
[0033] According to the HDD having the above structure, the
conductive portion 40 (copper tape 41), which is electrically
connected to the top cover 14, is provided at the intermediate
portion of the first short side wall 13b of the housing 10, thereby
improving an electromagnetic shielding characteristic of the
housing 10. Thus, the HDD can inhibit magnetic field resonance
occurring because of an external magnetic field, and improves
electro magnetic susceptibility (EMS).
[0034] FIG. 6 shows a reflection characteristic of electromagnetic
waves which are applied to the first short side wall 13b of the HDD
according to the first embodiment from the outside of the HDD. In
FIG. 6, the vertical axis represents the electromagnetic-wave
reflection characteristic (dB) (reflection characteristic of the
entire housing), and the horizontal axis represents the frequency
(GHz) of electromagnetic waves. The reflection characteristic of 0
dB means that applied electromagnetic waves are all reflected.
Also, the reflection characteristic of minus dB means that noise
(electromagnetic waves) enters the housing 10. As indicated by a
solid line in FIG. 6, in the HDD according to the first embodiment,
the reflection characteristic is nearly 0 dB in an entire width
region of the first short side wall 13b. That is, noise is
sufficiently reflected, and is prevented to enter into the housing
10.
[0035] On the other hand, as indicated by a broken line in FIG. 6,
in an HDD according to a comparative example, which includes no
conductive portion 40, the reflection characteristic is
significantly greater minus dB around a central portion of a first
short side wall 13b in the width direction thereof, which means
noise enters into the housing.
[0036] By virtue of the above, the HDD according to the first
embodiment can be effectively protected against electromagnetic
waves from the outside, thus improving EMS.
[0037] Next, HDDs according to another embodiment will be
described. In the following description, elements identical to
those in the first embodiment will be denoted by the same reference
numerals as in the first embodiment, respectively, and their
detailed description will be omitted or simplified. Elements
different from those of the first embodiment will be mainly
explained in detail.
Second Embodiment
[0038] FIG. 7 is a perspective view of an HDD according to a second
embodiment. FIG. 8 is a perspective exploded view of a side of the
HDD according to the second embodiment, where a first short side
wall 13b is provided. FIG. 9 is a side view of the HDD on a side
where the first short side wall 13b is provided.
[0039] As shown in FIGS. 7 and 8, in the second embodiment, a
conductive portion 40 of a housing 40 includes a convex portion 42
formed in a side edge portion of a short side of a top cover 14,
and a concave portion 44 formed in an upper portion of the first
short side wall 13b of a base 12. The convex portion 42 is formed
as a rectangular convex portion projecting toward the base 12, by
carrying out bending processing or drawing processing on part of
the top cover 14. Furthermore, the convex portion 42 is provided at
a substantially central portion of the short side of the top cover
14.
[0040] The concave portion 44 of the first short side wall 13b is
formed in a position, a shape, and a size corresponding to those of
the convex portion 42 of the top cover 14. To be more specific, the
concave portion 44 is substantially rectangular, formed at a
central portion of the first short side wall 13b in the
longitudinal direction thereof, and located outside of gasket
20.
[0041] When the top cover 14 is attached to and screwed on the base
12, the convex portion 42 of the top cover 14 is engaged with or
fitted in the concave portion 44 of the first short side wall 13b,
and in contact with a substantially central portion of the first
short side wall 13b. Thereby, the central portion of the first
short side wall 13b is electrically connected to the top cover 14
via the conductive portion 40.
[0042] As shown in FIG. 9, in the first short side wall 13b, d1=d2,
where d1 and d2 are distances between positions of screwed portions
(positions of screws 17) and the conductive portion 40,
respectively. In the second embodiment also, d1 and d2 are set to
70 mm so that the loop length becomes 2 GHz or more, as in the
first embodiment and the structure as shown in FIG. 5. When the
natural frequency at the first short side wall 13b become less than
2 GHz, noise may enter the HDD from the outside thereof, and cause
the HDD to malfunction. This is undesirable.
[0043] In the second embodiment, the other structural features are
the same as those of the first embodiment.
[0044] According to the HDD having the above structure, in an
intermediate portion of the first short side wall 13b of the
housing 10, the conductive portion 40, which is electrically
connected to the top cover 14, is provided, thereby improving a
magnetically shielding characteristic of the housing 10. For that
reason, the HDD can inhibits magnetic field resonance from
occurring because of an external magnetic field, and improve
electro magnetic susceptibility (EMS). In addition, in the second
embodiment also, it is possible to obtain the same advantage as in
the first embodiment.
[0045] With respect to the HDD according to the second embodiment,
a reflection characteristic for electromagnetic waves was measured,
and the same measurement result (simulation result) as shown in
FIG. 6 was obtained.
[0046] It should be noted that in the second embodiment, the shapes
of the convex portion 42 and the concave portion 44 included in the
conductive portion 40 are not limited to the rectangle, and can be
selected from various shapes. If the convex portion 42 of the top
cover 14 is sufficient to establish stable electrical connection to
the base 12, the concave portion 44 may be omitted. For example,
the height of the convex portion 42 may be the same as that of the
gap between the upper end surface of the side wall of the base and
the top cover, and the convex portion 42 may be in contact with the
upper end surface of the side wall.
[0047] While certain embodiments have been described, these
embodiments have been presented by way of example only, and are not
intended to limit the scope of the inventions. Indeed, the novel
embodiments described herein may be embodied in a variety of other
forms; furthermore, various omissions, substitutions and changes in
the form of the embodiments described herein may be made without
departing from the spirit of the inventions. The accompanying
claims and their equivalents are intended to cover such forms or
modifications as would fall within the scope and spirit of the
inventions.
[0048] In the disk drive, the number of magnetic disks is not
limited to three, i.e., may be one, two, or four or more. Also, the
number of magnetic heads may be increased or decreased in
accordance with the number of magnetic disks. The size of each of
the magnetic disks is not limited to 3.5 inches, i.e., may be
another size. The materials, shapes, sizes, etc., of the elements
forming the disk drive are not limited to those disclosed in the
above embodiments, and can be variously changed as occasion
demands. In addition, the location of the conductive portion is not
limited to the intermediate portion of the above first short side
wall; i.e., may be provided in a region between screwed portions of
a long side wall or another short side wall.
* * * * *