U.S. patent application number 09/899402 was filed with the patent office on 2002-03-14 for recording/reproducing device with read/write head carriage supporting voice coil of voice coil motor for driving the carriage assembly.
This patent application is currently assigned to MITSUMI ELECTRIC CO., LTD.. Invention is credited to Itoh, Toshimitsu, Majima, Yoshihide, Shimazu, Teruo, Shimizu, Toshiharu.
Application Number | 20020030941 09/899402 |
Document ID | / |
Family ID | 27471640 |
Filed Date | 2002-03-14 |
United States Patent
Application |
20020030941 |
Kind Code |
A1 |
Shimazu, Teruo ; et
al. |
March 14, 2002 |
Recording/reproducing device with read/write head carriage
supporting voice coil of voice coil motor for driving the carriage
assembly
Abstract
In a recording/reproducing device for use in recording and
reproducing data on and from a recording medium while moving
read/write head means relative to the recording medium in a moving
direction, which comprises a carriage supporting the read/write
head means and guided by a guiding member in the moving direction,
and a voice coil motor comprising a voice coil and a magnetic
circuit device for driving the carriage in the moving direction.
The carriage has a coil holding portion by which the voice coil is
fixedly held in the condition that the coil axis is arranged in the
moving direction. The voice coil is applied with a driving electric
current for driving the carriage. The magnetic circuit device is
fixedly disposed adjacent to the voice coil to generate a magnetic
field intersecting the driving current flowing through the voice
coil, the voice coil moving in the moving direction together with
the carriage by an interaction of the driving current and the
magnetic field.
Inventors: |
Shimazu, Teruo; (Atsugi-shi,
JP) ; Shimizu, Toshiharu; (Tokyo, JP) ;
Majima, Yoshihide; (Hatano-shi, JP) ; Itoh,
Toshimitsu; (Atsugi-shi, JP) |
Correspondence
Address: |
FRISHAUF, HOLTZ, GOODMAN &
LANGER & CHICK, PC
767 THIRD AVENUE
25TH AVE
NEW YORK
NY
10017-2023
US
|
Assignee: |
MITSUMI ELECTRIC CO., LTD.
Tokyo
JP
|
Family ID: |
27471640 |
Appl. No.: |
09/899402 |
Filed: |
July 5, 2001 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
09899402 |
Jul 5, 2001 |
|
|
|
09562883 |
May 1, 2000 |
|
|
|
Current U.S.
Class: |
360/266.9 ;
360/266.7; G9B/5.187 |
Current CPC
Class: |
G11B 5/5521
20130101 |
Class at
Publication: |
360/266.9 ;
360/266.7 |
International
Class: |
G11B 005/55 |
Foreign Application Data
Date |
Code |
Application Number |
May 27, 1996 |
JP |
131836/1996 |
May 27, 1996 |
JP |
131919/1996 |
May 27, 1996 |
JP |
132344/1996 |
May 27, 1996 |
JP |
132347/1996 |
Claims
What is claimed is:
1. A recording/reproducing device for use in recording and
reproducing data on and from a recording medium while moving
read/write head means relative to said recording medium in a moving
direction, which comprises: a carriage supporting said read/write
head means; guide means fixedly disposed and slidably supporting
said carriage for guiding said carriage in said moving direction; a
voice coil motor for driving said carriage in said moving
direction, said voice coil motor comprising a voice coil having a
coil axis and a magnetic circuit device generating a magnetic
field; said carriage having a coil holding portion projecting
therefrom, said voice coil being fixedly held on said coil holding
portion in the condition that said coil axis is arranged in said
moving direction, said coil being applied with a driving electric
current for driving said carriage; and said magnetic circuit device
fixedly disposed adjacent to said voice coil to generate a magnetic
field intersecting the driving current flowing through said voice
coil, said voice coil moving in the moving direction together with
said carriage by an interaction of said driving current and said
magnetic field.
2. A recording/reproducing device as claimed in claim 1, wherein
said magnetic circuit device comprises: a center yoke fixedly
disposed to extend in the moving direction through said voice coil
and having opposite ends, said voice coil being movable along said
center yoke; a back yoke extending in parallel to said center yoke
and having opposite end bent portions, said opposite end bent
portions being connected to said opposite ends of said center yoke
to form an endless shape member, said back yoke having a principal
surface facing said center yoke with a space therebetween defined
by said opposite end bent portions, said voice coil being partially
disposed within said space; and a magnet attached onto said
principal surface of said back yoke within said space, said magnet
being magnetized in a direction perpendicular to said principal
surface so as to produce said magnetic field.
3. A recording/reproducing device as claimed in claim 2, wherein
said coil holding portion is a coil bobbin slidably fitted on said
center yoke, said voice coil wound on said coil bobbin.
4. A recording/reproducing device as claimed in claim 2, wherein
said carriage has a carriage body, and said coil holding portion is
fixed to said carriage body.
5. A recording/reproducing device as claimed in claim 4, wherein
said coil holding portion is a coil bobbin laterally projecting
from a side wall of said carriage body and slidably fitted on said
center yoke, said coil bobbin is fixed to said carriage body, and
said voice coil is wound on said coil bobbin.
6. A recording/reproducing device as claimed in claim 5, wherein
said carriage body is provided with clamping means, and said coil
bobbin is clamped and fixedly supported by said clamping means.
7. A recording/reproducing device as claimed in claim 5, wherein
said coil bobbin is integrally formed with said carriage body in a
single body by a plastic molding process.
8. A recording/reproducing device as claimed in claim 4, wherein
said coil holding portion is fixed onto a side wall of said
carriage body, said voice coil being supported on and fixed to said
coil holding portion.
9. A recording/reproducing device as claimed in claim 8, wherein
said coil holding portion is clamping means formed integral with
said carriage body, said voice coil is clamped by said clamping
means.
10. A recording/reproducing device as claimed in claim 4, wherein
said carriage body and said coil holding portion are formed in a
single molded body of a plastic resin, said voice coil being molded
in said molded body.
11. A recording/reproducing device as claimed in claim 2, wherein
at least one additional magnetic circuit device like said magnetic
circuit device disposed in parallel with each other.
12. A recording/reproducing device as claimed in claim 11, wherein
wherein said additional magnetic circuit device has an additional
center yoke like said center yoke, and said voice coil collectively
surrounds around said center yoke and said additional center
yoke.
13. A recording/reproducing device as claimed in claim 11, wherein
said additional magnetic circuit device has an additional center
yoke like said center yoke, said voice coil motor having an
additional voice coil, and said voice coil and said additional
voice coil are slidably fitted on said center yoke and said
additional center yoke, respectively.
14. A recording/reproducing device as claimed in claim 2, said
carriage assembly comprising a carriage body of a resin material
connected to said voice coil, and a projecting member slidably
coupled to said guide means passing therethrough for driving said
voice coil, said projecting member having said coil holding portion
holding a lower side of said voice coil.
15. A recording/reproducing device as claimed in claim 14, said
coil holding portion extending in a transversal direction
perpendicular to said predetermined direction to hold said voice
coil, said coil holding portion having a size greater than a half
of the width of said voice coil in said transversal direction.
16. A magnetic recording/reproducing device as claimed in claim 14,
said coil holding portion and said voice coil being adhered by an
adhesive.
17. A recording/reproducing device as claimed in claim 14, said
carriage body and one of arc-shaped portions of said voice coil
being adhered by an adhesive.
18. A magnetic recording/reproducing device as claimed in claim 14,
said carriage body having a fitting portion integrally holding one
of arc-shaped portions of said voice coil, said one arc-shaped
portion of the voice coil being connected to said fitting portion
upon molding of said carriage body.
19. A magnetic recording/reproducing device as claimed in claim 18,
at least an outer peripheral surface of the arc-shaped portion of
said voice coil being integrally formed with said fitting portion.
Description
BACKGROUND OF THE INVENTION
[0001] This invention relates to a recording/reproducing device for
recording and reproducing data on and from a recording medium
through a read/write head and, in particular, to a
recording/reproducing mechanism for driving a carriage assembly
with the read/write head mounted thereon by a voice coil motor in a
predetermined direction relative to the recording medium.
[0002] As a typical one of such a recording/reproducing device,
there is well known in the prior art a disk drive for recording and
reproducing data on and from a magnetic recording medium by a
magnetic head. The magnetic recording medium is a so called
flexible disk and is usually housed in a hard case or a cartridge.
The cartridge containing the flexible disk is called a floppy disk.
In recent years, the flexible disk is more and more increased in
storage capacity. Development has been made of those flexible disks
having a storage capacity as large as 128 megabytes in contrast
with those having a storage capacity on the order between one and
two megabytes. The former and the latter flexible disks will
hereafter be referred to as large-capacity flexible and
normal-capacity flexible disks, respectively. Following such
remarkable increase in storage capacity, an improved disk drive has
also been developed so as to deal with the large-capacity flexible
disks.
[0003] The disk drive for use with the normal-capacity flexible
disks is different in mechanism from that intended for use with the
large-capacity flexible disks. One such difference lies in the
structure of a driving mechanism for driving a carriage-assembly
with a magnetic head relative to the flexible disk received in the
disk drive. More specifically, the disk drive for the
normal-capacity flexible disks uses a stepping motor as the driving
mechanism. On the other hand, the disk drive for the large-capacity
flexible disks uses a linear motor such as a voice coil motor
(VCM).
[0004] The carriage assembly is moved in a carriage moving
direction which is a predetermined radial direction of the flexible
disk.
[0005] The voice coil motor used as the driving mechanism in the
disk drive for the large-capacity flexible disks comprises a pair
of voice coils fixedly mounted on both sides of the carriage
assembly each having a coil axis arranged in the carriage moving
direction, and a pair of magnetic circuit devices fixedly disposed
adjacent the voice coils, respectively, each for generating a
magnetic field in a direction intersecting an electric current
flowing through each of the voice an electric current flowing
through each of the voice coils.
[0006] Each of the magnetic circuit devices typically comprises a
permanent magnet polarized along its thickness, and a yoke member.
The yoke member comprises a center yoke, a back yoke, and a pair of
side yokes. The center yoke extends in the carriage moving
direction and passes through the corresponding one of the voice
coils along the coil axis. The back yoke extends in parallel to the
center yoke at a certain distance therefrom and has a principal
surface faced to the center yoke. The side yokes connect the center
yoke with the back yoke at their one ends and the other ends to
establish an endless form. The permanent magnet is fixedly attached
to the principal surface of the back yoke. Each of the center yoke,
the back yoke, and the side yokes is made of a steel plate having a
thickness of at least 3 mm.
[0007] The magnetic circuit device produces the magnetic field
across a space between the center yoke and the back yoke. The
electric current flows through the voice coil in a direction
intersecting the magnetic field. The interaction between the
electric current and the magnetic field produces driving force to
drive the voice coil in the carriage moving direction along the
center yoke. In this manner, the carriage assembly is moved in the
carriage moving direction in response to the driving force of the
voice coil motor.
[0008] Thus, a combination of the voice coil motor and the carriage
assembly serves as a magnetic recording/reproducing mechanism in
the disk drive.
[0009] In the above-mentioned magnetic recording/reproducing
mechanism, the magnetic circuit device of the voice coil motor
comprises the yoke member composed of the center yoke, the back
yoke, and the side yokes. Thus, the yoke member includes a
relatively large number of components.
[0010] In the magnetic circuit device, the permanent magnet, the
center yoke, the back yoke, and the side yokes are equal in width
to one another. As described above, the voice coil motor produces
the driving force by the interaction between the electric current
flowing through the-voice coil and the magnetic field produced by
the magnetic circuit device. The intensity of the driving force
depends on the magnitude of the electric current and the number of
magnetic fluxes intersecting the voice coil. In order to increase
the driving force, it is necessary either to increase the electric
current flowing through the voice coil or to increase the number of
the magnetic fluxes across the voice coil. However, the electric
current to flow through the voice coil is limited in magnitude.
[0011] On the other hand, the magnetic field intersecting the voice
coil, i.e., the number of the magnetic fluxes can be increased if
the permanent magnet is made of an advanced magnetic material or if
the permanent magnet, the center yoke, the back yoke, and the side
yokes are increased in width. However, the use of the permanent
magnet made of such an advanced magnetic material will increase the
cost of the voice coil motor because the advanced magnetic material
is expensive. On the other hand, the increase in width of the
permanent magnet, the center yoke, the back yoke, and the side
yokes inevitably increases the size and the weight of the voice
coil motor.
[0012] In the disk drive, it is a general practice that the voice
coil is fixed to a side wall of the carriage assembly by the use of
an adhesive.
[0013] However, it is difficult to fix the voice coil to the
carriage assembly with an accurate position. Furthermore, the voice
coil is often disconnected or released from the carriage assembly
because of deterioration of the adhesive resulting from various
factors, such as generation of heat within the device and the lapse
of time.
SUMMARY OF THE INVENTION
[0014] It is therefore an object of this invention to provide a
recording/reproducing device with a voice coil motor having a
magnetic circuit device with a reduced number of components.
[0015] It is another object of this invention to provide a
recording/reproducing device with a cost-effective and small-sized
voice coil motor capable of providing a sufficient driving
force.
[0016] It is still another object of this invention to provide a
recording/reproducing device in which a voice coil is accurately
attached to a predetermined position of a carriage assembly.
[0017] It is yet another object of this invention to provide a
recording/reproducing device in which a voice coil is securely
coupled to a carriage assembly with improved reliability.
[0018] It is a further object of this invention to provide a
recording/reproducing device in which a voice coil is attached to a
carriage assembly over a wide area to achieve reliable
coupling.
[0019] According to this invention, there is provided a
recording/reproducing device for use in recording and reproducing
data on and from a recording medium while moving read/write head
means relative to the recording medium in a moving direction, which
comprises a carriage supporting the read/write head means; guide
means fixedly disposed and slidably supporting the carriage for
guiding the carriage in the moving direction; a voice coil motor
for driving the carriage in the moving direction, the voice coil
motor comprising a voice coil having a coil axis and a magnetic
circuit device generating a magnetic field; the carriage having a
coil holding portion projecting therefrom, the voice coil being
fixedly held on the coil holding portion in the condition that the
coil axis is arranged in the moving direction, the coil being
applied with a driving electric current for driving the carriage;
and the magnetic circuit device fixedly disposed adjacent to the
voice coil to generate a magnetic field intersecting the driving
current flowing through the voice coil, the voice coil moving in
the moving direction together with the carriage by an interaction
of the driving current and the magnetic field.
BRIEF DESCRIPTION OF THE DRAWING
[0020] FIG. 1 is a perspective view of a voice coil motor in a
known disk drive;
[0021] FIG. 2 is a plan view illustrating an internal structure of
a disk drive to which a magnetic recording/reproducing mechanism
according to a first embodiment of this invention is applied;
[0022] FIG. 3 is a schematic plan view of a carriage assembly in
FIG. 2;
[0023] FIG. 4 is a schematic side view of the carriage assembly in
FIG. 3;
[0024] FIG. 5 is a perspective view of a magnetic circuit device of
a voice coil motor in FIG. 2;
[0025] FIG. 6 is a side view of the magnetic recording/reproducing
mechanism in FIG. 2;
[0026] FIG. 7 is a plan view of the magnetic recording/reproducing
mechanism in FIG. 6;
[0027] FIG. 8 is a sectional view taken along a line VIII-VIII in
FIG. 6;
[0028] FIG. 9 is a sectional view of a magnetic
recording/reproducing mechanism according to a second embodiment of
this invention;
[0029] FIG. 10 is a sectional view of a magnetic
recording/reproducing mechanism according to a third embodiment of
this invention;
[0030] FIG. 11 is a front view of a magnetic recording/reproducing
mechanism according to a fourth embodiment of this invention;
[0031] FIG. 12 is a plan view of the magnetic recording/reproducing
mechanism in FIG. 11;
[0032] FIG. 13 is a sectional view taken along a line XIII-XIII in
FIG. 11;
[0033] FIG. 14 is a front view of a magnetic recording/reproducing
mechanism according to a fifth embodiment of this invention;
[0034] FIG. 15 is a plan view of a carriage assembly in FIG.
14;
[0035] FIG. 16 is a side view of the carriage assembly in FIG.
15;
[0036] FIG. 17 is a rear view of the carriage assembly in FIG. 15;
and
[0037] FIG. 18 is a sectional view of a magnetic
recording/reproducing mechanism according to a sixth embodiment of
this invention.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0038] In order to facilitate an understanding of this invention, a
voice coil motor in a known disk drive will at first be described
with reference to FIG. 1. The voice coil motor comprises a magnetic
circuit device and a voice coil 3 which is fixed to a side wall of
a carriage assembly (not shown) by an adhesive agent. The magnetic
circuit device comprises a permanent magnet 1 magnetized in a
direction of its thickness, and a yoke member 2. The yoke member 2
comprises a center yoke 2a, a back yoke 2b, and a pair of side
yokes 2c. The center yoke 2a extends in an extending direction
coincident with a moving direction of the carriage assembly and
passes through the voice coil 3. The back yoke 2b extends in
parallel to the center yoke 2a at a certain distance therefrom and
has a principal surface faced to the center yoke 2a. The side yokes
2c are connected to the center yoke 2a and the back yoke 2b at
their one ends and the other ends to establish magnetic connection
therebetween. The permanent magnet 1 is fixedly attached to the
principal surface of the back yoke 2b. Each of the center yoke 2a,
the back yoke 2b, and the side yokes 2c is made of a steel plate
having a thickness of at least 3 mm.
[0039] The magnetic circuit device produces a magnetic field across
a space between the center yoke 2a and the back yoke 2b. An
electric current flows through the voice coil 3 in a direction
intersecting the magnetic field. The interaction between the
electric current and the magnetic field produces driving force to
drive the voice coil 3 in the extending direction of the center
yoke 2a, that is, the moving direction of the carriage assembly. In
this manner, the carriage assembly is moved in the moving direction
in response to the driving force of the voice coil motor.
[0040] Thus, a combination of the voice coil motor and the carriage
assembly serves as the magnetic recording/reproducing mechanism in
the disk drive.
[0041] However, the known disk drive has problems as described in
the preamble.
[0042] Now referring to FIG. 2, description will be made as regards
a magnetic recording/reproducing device according to a first
embodiment of this invention. The magnetic recording/reproducing
device is a disk drive for recording and reproducing data on and
from a normal-capacity or a large-capacity flexible disk (not
shown). The flexible disk is inserted into the disk drive from a
direction indicated by an arrow A in FIG. 2 and is held by a disk
table assembly 120 which is rotatably supported on a main frame 11.
The disk table assembly 120 is rotated by a disk drive motor (not
shown) disposed on a back surface of the main frame 11. The
flexible disk is rotated in response to the rotation of the disk
table assembly 120. The main frame 11 is also provided on the back
surface thereof with a printed wiring board (not shown) on which a
number of electronic parts are mounted.
[0043] The disk drive comprises a pair of upper and lower magnetic
heads (not shown) for recording and reproducing data on and from
opposite surfaces of the flexible disk. The magnetic heads are
supported by a carriage assembly 22 through a pair of upper and
lower gimbal plates collectively depicted at 13 in FIG. 2. The
carriage assembly 22 is positioned above the main frame 11 at a
distance from the main frame 11. The carriage assembly 22 holds the
magnetic heads so that the magnetic heads are moved in a
predetermined direction (depicted by an arrow B in FIG. 2) with
respect to the flexible disk. The predetermined direction is a
radial direction of the flexible disk. As will later be described,
the carriage assembly 22 is supported and guided at both lateral
sides thereof by a pair of guide bars 14 extending in the
predetermined direction B.
[0044] The carriage assembly 22 is driven in the predetermined
direction B by a voice coil motor 20. The voice coil motor 20 is
positioned at a rear portion of the disk drive. The voice coil
motor 20 comprises a voice coil 21, and a pair of magnetic circuit
devices 50 each of which is for generating a magnetic field in a
direction intersecting an electric current flowing through the
voice coil 21.
[0045] Referring to FIGS. 3 and 4 in addition, the carriage
assembly 22 comprises a carriage body 24 of a resin material, an
upper carriage 222a, and a lower carriage 222b. The upper and the
lower gimbal plates depicted at 13a and 13b are formed at free ends
of the upper and the lower carriages 222a and 222b, respectively.
The voice coil 21 is integrally coupled to the carriage body 24 on
the both lateral sides thereof. The upper and the lower gimbal
plates 13a and 13b hold the upper and the lower magnetic heads
depicted at 17a and 17b in FIG. 4, respectively. A first projecting
member 220a projects from the lower carriage 222b on both lateral
sides thereof. Likewise, a second projecting member 220b projects
from the carriage body 24 on the both lateral sides thereof at its
lower portion. The guide bars 14 extend in parallel to each other
in the predetermined direction B and pass through the first and the
second projecting members 220a and 220b. The upper carriage 222a is
pivotable around a fixed end connected to the carriage body 24.
[0046] Referring to FIGS. 2 and 5 through 8, the magnetic
recording/reproducing mechanism according to the first embodiment
of this invention will be described in detail. The magnetic
recording/reproducing mechanism illustrated in FIG. 2 comprises the
voice coil motor 20 and the carriage assembly 22 coupled thereto.
The voice coil motor 20 comprises a voice coil 21 and a pair of the
magnetic circuit devices 50.
[0047] Each of the magnetic circuit devices 50 comprises a
permanent magnet 200 magnetized in a direction of its thickness,
and a yoke member. The yoke member comprises a center yoke 202 and
a back yoke 203. The center yoke 202 is fixedly disposed to extend
in the predetermined direction B or a moving direction of the
carriage assembly 22 and passes through the voice coil 21. The back
yoke 203 extends in parallel to the center yoke 202 at a certain
distance therefrom and has a principal surface 203a faced to the
center yoke 202. The back yoke 203 has end portions 203b each of
which is bent downward by means of press working to form a
generally right angle. The end portions 203b are physically and
magnetically connected to corresponding ends of the center yoke 202
to form an endless-shape member. A permanent magnet 200 is fixedly
attached to the principal surface 203a of the back yoke 203. Each
of the center yoke 202 and the back yoke 203 is made of a steel
plate having a thickness of at least 3 mm.
[0048] The center yoke 202, the back yoke 203, the permanent magnet
200 have a center yoke width Wc, a back yoke width Wb, and a magnet
width Wm (Wm is not indicated in FIG. 5), respectively. Each of the
magnet width Wm and the back yoke width Wb are greater than the
center yoke width Wc. In this embodiment, the magnet width Wm is
equal to the back yoke width Wb. With this structure, the magnetic
field effectively acts on the voice coil 21 with a greater number
of magnetic fluxes. Therefore, sufficient driving force is assured
with a less number of components without the side yokes in the
conventional mechanism.
[0049] The magnetic recording/reproducing mechanism comprising a
combination of the voice coil motor 20 and the carriage assembly 22
will be described in detail with reference to FIGS. 6 through
8.
[0050] The carriage body 24 is connected through a pair of carriage
spring portions 221 to the upper and the lower carriages 222a and
222b, respectively. The lower carriage 222b is not illustrated in
FIGS. 7 and 8.
[0051] The first and the second projecting members 220a and 220b
are slidably coupled to the guide bars 14 extending in the
predetermined direction B. Thus, the carriage assembly 22 is
movable in the predetermined direction B.
[0052] The carriage spring portions 221 having elasticity are fixed
at their one ends to upper and lower surfaces of the carriage body
24, respectively, through plate members 223 and bolts 224. The
other ends of the carriage spring portions 221 are fixedly
connected to one ends of the upper and the lower carriages 222a and
222b, respectively. Thus, the upper and the lower carriages 222a
and 222b are elastically supported by the carriage spring portions
221. As illustrated in FIG. 4, the upper and the lower magnetic
heads 17a and 17b are attached to inner surfaces of the upper and
the lower gimbal plates 13a and 13b which are connected to the free
ends of the upper and the lower carriages 222a and 222b,
respectively.
[0053] As shown in FIGS. 6 and 7, the voice coil 21 is wound on a
bobbin 23. The bobbin 23 is a flat cylindrical shape comprising two
confronting flat portions and two arc-shaped portions connecting
the flat portions at both ends. The bobbin has a pair of flange
portions 230 slightly protruding from the arc-shaped portions,
respectively. The bobbin 23 surrounds collectively both of the
center york.
[0054] The carriage body 24 has a pair of clamping portions 220d by
which the bobbin 23 is clamped and supported. Therefore, the bobbin
23 serves as a coil holding portion of the carriage assembly, and
the voice coil 23 can be reliably fixed to the carriage assembly
through the bobbin. The voice coil 21 is preliminarily wound around
the bobbin 23 before it is fixed to the carriage assembly 22. The
bobbin 23 with the voice coil 21 wound therearound is fixed to the
carriage assembly 22 and then fitted to the center yokes 202 to
surround the center yokes 202 so that the bobbin 23 is movable in
the longitudinal direction of the center yokes 202, namely, the
predetermined direction B.
[0055] The main frame 11 has a pair of seating portions 110 for
separating the magnetic circuit devices 50 from a principal surface
11a of the main frame 11. Each seating portion 110 has a pair of
protrusions 110a upwardly protruding therefrom. Each protrusion
110a has a height smaller than the thickness of the center yoke
202. As illustrated in FIG. 5, each center yoke 202 has notches
202a formed at both ends thereof for fitting the protrusions
110a.
[0056] Thus, the protrusions 110a of the seating portion 110 serve
to fixedly position the center yoke 202. Each of the back yokes 203
has a pair of protrusions 203c formed at both longitudinal ends
thereof to be fitted in the notches 202a. Each protrusion 203 has a
height substantially equal to a difference between the thickness of
each center yoke 202 and the height of each protrusion 110a of each
seating portion 110. Thus, the notches 202a of the center yoke 202
serve to position the back yoke 203.
[0057] In the voice coil motor 20 of the above-mentioned structure,
the magnetic field is generated in each of spaces between the
center yokes 202 and the back yokes 203. The electric current flows
through the voice coil 21 in a direction intersecting the magnetic
field to produce driving force in the longitudinal direction of the
center yoke 202 as a result of interaction between the electric
current and the magnetic field. The driving force moves the
carriage assembly 22 in the predetermined direction B coincident
with the longitudinal direction of the center yoke 202. The
movement of the carriage assembly 22 moves the upper and the lower
magnetic heads 17a and 17b (FIG. 4) relative to the flexible disk
(not shown).
[0058] In the first embodiment, a pair of the magnetic circuit
devices 50 are provided. However, use may also be made of a single
magnetic circuit device 50 or three or more magnetic circuit
devices 50. Although the center yokes 202 are collectively
surrounded by a single bobbin 23 in the first embodiment, two
bobbins 23 may be used to be slidably fitted on the center yokes
202, respectively.
[0059] It is a modification that the bobbin 23 is omitted and the
voice coil 21 is hard to maintain a flat cylindrical shape similar
to the bobbin. In that case, the voice coil is clamped and
supported by the clamping portions 220d. The clamping potions serve
as the coil holding portion of the carriage assembly.
[0060] Referring to FIG. 9, a magnetic recording/reproducing
mechanism according to a second embodiment of this invention is
substantially similar to that of the first embodiment except that
the bobbin 23 and the clamping portion of the carriage body 24 are
integrally formed into a single body of plastic resin by a molding
process. Similar parts are designated by like reference numerals
and will not be described any longer.
[0061] In the first and the second embodiments, the voice coil 21
is fixed to the clamping portion 220d of the carriage assembly 22
by the use of an adhesive. Specifically, the adhesive is applied
onto a predetermined portion of the voice coil 21. The voice coil
21 is then inserted in the clamping portions 220d. At this time,
the voice coil 21 is accurately positioned by the clamping portions
220d with respect to the carriage assembly 22. Thereafter, the
adhesive is solidified.
[0062] Thus, positioning and attachment of the voice coil 21 can be
easily carried out in the first and the second embodiments by means
of the clamping portions 220d.
[0063] Referring to FIG. 10, a magnetic recording/reproducing
mechanism according to a third embodiment of this invention is
similar to the second embodiment except that the bobbin 23 and the
carriage portion 24 are integrally formed into a single body by
molding and that the bobbin 23 has flange portions 230 formed at
both ends thereof to project outward. Similar parts are designated
by like reference numerals and will not be described any
longer.
[0064] In the third embodiment, positioning and attachment of the
voice coil 21 can be easily carried out by means of the flange
portions 230.
[0065] Referring to FIGS. 11 through 13, a magnetic
recording/reproducing mechanism according to a fourth embodiment of
the present invention is basically similar to the first embodiment.
Similar parts are designated by like reference numerals and will
not be described any longer.
[0066] In the fourth embodiment, a pair of the voice coils 21 are
used and slidably fitted on the two center yokes 202, respectively.
A pair of clamping portions 220e are formed on both side walls of
the carriage body 24 of the carriage assembly 22 and clamp and
support the voice coils 21, respectively. Each of the clamping
portions 220e is an L-shaped member formed or mounted on the side
wall with an end of the a foot portion of the L being fixed to the
side wall and the leg portion of the L extends in parallel with the
side wall to form a gap therebetween. The voice coil 21 passes
through the gap and is held by the side wall and the clamping
portion 220e, that is, the leg of the L-shaped member. The clamping
portions serves as the coil holding portions.
[0067] In a modification, two coil bobbins are clamped and
supported by the side walls and the clamping portions 220e, and the
voice coils 21 are wound on the bobbins, respectively. In the case,
the bobbins serve as the coil holding portions. The clamping
portions 220e are similar in function and effect to that of the
clamping portions 220d in the first embodiment.
[0068] Referring to FIGS. 14 through 17, a magnetic
recording/reproducing mechanism according to a fifth embodiment is
basically similar to the fourth embodiment in that the coil holding
portions are formed on both side walls of the carriage body. The
carriage assembly 22 is similar in structure to that illustrated in
FIGS. 3 and 4. Similar parts are designated by like reference
numerals and will not be described any longer.
[0069] In the fifth embodiment, the second projecting member 220b
integral with the carriage body 24 has a pair of holding portions
226d of a thin plate shape facing and supporting the lower surfaces
of the voice coils 21. The holding portions 226d extend from the
second projecting member 220b towards but under the central yokes
202, respectively. The voice coils 21 are mounted on and adhered to
the holding portions 226d, respectively.
[0070] As illustrated in FIG. 15, each voice coil 21 is assumed to
have a longitudinal size L in a transversal direction perpendicular
to the predetermined direction. In this event, each holding portion
226d has a size slightly greater than L/2 in the transversal
direction.
[0071] The voice coils 21 and the carriage body 24 are directly
adhered by the adhesive. In addition, the holding portions 226d and
the voice coils 21 are adhered by the adhesive. With this
structure, the voice coils 21 are stably mounted and fixed to the
holding portions 226d.
[0072] In FIG. 15, a wiring member 125 such as a flexible printed
circuit (FPC) has one end connected to the carriage assembly 22 and
the other end connected to a power supply terminal of an electronic
apparatus (not shown).
[0073] In this embodiment, the voice coils 21 can be reliably fixed
to the carriage assembly 22 with a correct position insured by
means of the holding portions 226d.
[0074] In a modification of this embodiment, a coil bobbin is fixed
to each of the holding portions 226d and the voice coil 21 can be
wound and held on the bobbin. The bobbin can be formed into an
integral form with the holding potion by a plastic molding
process.
[0075] Referring to FIG. 18, a magnetic recording/reproducing
mechanism according to a sixth embodiment is substantially similar
to the fifth embodiment. Similar parts are designated by like
reference numerals and will not be described any longer.
[0076] In the sixth embodiment, the carriage body 24 has a pair of
the holding portions 226d and a pair of fitting portions 241a. Each
of the holding portions 226d serves to hold a part of a lower
peripheral surface of the voice coil 21. Each of the fitting
portions 241a serves to hold one of arc-shaped side surfaces of the
voice coil 21.
[0077] In a plastic molding process of the carriage body 24 with
the holding portions 226d, the voice coils 21 are molded in and is
fixedly held by the carriage body. That is, the one arc-shaped side
surface of the voice coil 21 and the fitting portion 241a are
integrally formed upon resin molding. Each of the holding portions
226d and each of the voice coils 21 are directly bonded together
upon resin molding. With this structure, the voice coils 21 are
stably supported and fixed by the fitting portions 241a. The
fitting portion 241a is formed at least in a region corresponding
to the arc-shaped side surface of the voice coil 21. The fitting
portion 241a may be extended to the lower peripheral surface, the
upper peripheral surface, and the inside of the arc-shaped side
surface of the voice coil 21.
[0078] Although this invention has thus far been described in
conjunction with the several preferred embodiments thereof, it will
be understood that this invention is not restricted to the
foregoing embodiments and can be modified in various manners within
a scope of this invention. For example, this invention is
applicable not only to the disk drive but also various-type
recording/reproducing apparatuses such as an optical disk
recording/reproducing device.
* * * * *