U.S. patent application number 13/071706 was filed with the patent office on 2011-09-29 for lens drive device.
This patent application is currently assigned to NIDEC SANKYO CORPORATION. Invention is credited to Kiyoshi MIYAZAKI, Tatsuki WADE.
Application Number | 20110235197 13/071706 |
Document ID | / |
Family ID | 44656203 |
Filed Date | 2011-09-29 |
United States Patent
Application |
20110235197 |
Kind Code |
A1 |
MIYAZAKI; Kiyoshi ; et
al. |
September 29, 2011 |
LENS DRIVE DEVICE
Abstract
A lens drive device for use with at least one lens may include a
movable body holding a lens, a fixed body movably holding the
movable body, and a drive mechanism for driving the movable body in
the optical axis direction. The drive mechanism may include a drive
coil fixed to the movable body and a plurality of drive magnets
which is fixed to the fixed body and magnetized so that magnetic
poles are different from each other in the optical axis direction.
The fixed body may include an outer peripheral side magnetic member
and an end face side magnetic member and an inner peripheral face
of the outer peripheral side magnetic member and a side face of the
drive magnet are faced each other through a predetermined space.
The drive coil is disposed between the drive magnet and the inner
peripheral face of the outer peripheral side magnetic member.
Inventors: |
MIYAZAKI; Kiyoshi; (Nagano,
JP) ; WADE; Tatsuki; (Nagano, JP) |
Assignee: |
NIDEC SANKYO CORPORATION
Nagano
JP
|
Family ID: |
44656203 |
Appl. No.: |
13/071706 |
Filed: |
March 25, 2011 |
Current U.S.
Class: |
359/824 |
Current CPC
Class: |
H02K 41/0356 20130101;
G02B 7/08 20130101 |
Class at
Publication: |
359/824 |
International
Class: |
G02B 7/04 20060101
G02B007/04 |
Foreign Application Data
Date |
Code |
Application Number |
Mar 25, 2010 |
JP |
2010-070526 |
Claims
1. A lens drive device for use with at least one lens comprising: a
movable body which holds the lens and is movable in an optical axis
direction of the lens; a fixed body which movably holds the movable
body in the optical axis direction; and a drive mechanism for
driving the movable body in the optical axis direction; wherein the
drive mechanism comprises: a drive coil which is fixed to the
movable body; and a plurality of drive magnets which are formed in
a substantially columnar shape or a substantially plate shape and
fixed to the fixed body, the drive magnets being magnetized so that
a magnetic pole of one end face is different from a magnetic pole
of the other end face in the optical axis direction; wherein the
fixed body comprises: an outer peripheral side magnetic member
which is formed of magnetic material and formed in a substantially
tube-like shape and structures an outer peripheral face of the
fixed body; and an end face side magnetic member which is formed of
magnetic material and to which the one end face of the drive magnet
is fixed; wherein an inner peripheral face of the outer peripheral
side magnetic member and a side face of the drive magnet are faced
each other through a predetermined space; wherein the outer
peripheral side magnetic member, the end face side magnetic member
and the drive magnet are disposed so that a magnetic field is
formed so as to pass through the drive magnet, the end face side
magnetic member and the outer peripheral side magnetic member and
returned to the other end face of the drive magnet from the inner
peripheral face of the outer peripheral side magnetic member, or
returned to the inner peripheral face of the outer peripheral side
magnetic member from the other end face of the drive magnet; and
wherein the drive coil is disposed between the other end face side
of the drive magnet and the inner peripheral face of the outer
peripheral side magnetic member.
2. The lens drive device for use with at least one lens according
to claim 1, wherein the outer peripheral side magnetic member and
the end face side magnetic member are formed in an integral
manner.
3. The lens drive device for use with at least one lens according
to claim 2, wherein the fixed body is provided with a cover member
which is formed in a substantially bottomed tube-like shape in
which the end face side magnetic member is a bottom part and the
outer peripheral side magnetic member is a tube part that is
integrally formed with the bottom part, and the end face side
magnetic member structures an end face on an object to be
photographed or imaged side of the lens drive device.
4. The lens drive device for use with at least one lens according
to claim 3, wherein the inner peripheral face of the outer
peripheral side magnetic member and the side face of the drive
magnet which are faced each other are substantially parallel to
each other.
5. The lens drive device for use with at least one lens according
to claim 4, further comprising a second end face side magnetic
member which is formed of magnetic material and fixed to the other
end face of the drive magnet, wherein the drive coil is formed in a
tube-like shape so as to be movable between the side face of the
drive magnet and the inner peripheral face of the outer peripheral
side magnetic member, and wherein a width in the optical axis
direction of the drive coil is set to be a width in which the
second end face side magnetic member is always located on an inner
peripheral side of the drive coil over a moving range of the
movable body.
6. The lens drive device for use with at least one lens according
to claim 5, wherein a shape of the drive magnet when viewed in the
optical axis direction is substantially same as a shape of the
second end face side magnetic member when viewed in the optical
axis direction.
7. The lens drive device for use with at least one lens according
to claim 1, wherein an end face of the end face side magnetic
member is abutted with the inner peripheral face of the outer
peripheral side magnetic member.
8. The lens drive device for use with at least one lens according
to claim 1, further comprising a second end face side magnetic
member which is formed of magnetic material and fixed to the other
end face of the drive magnet, wherein the magnetic field is
directed from the inner peripheral face of the outer peripheral
side magnetic member to the other end face of the drive magnet
through the second end face side magnetic member, or the magnetic
field is directed from the other end face of the drive magnet to
the inner peripheral face of the outer peripheral side magnetic
member through the second end face side magnetic member.
9. The lens drive device for use with at least one lens according
to claim 8, wherein the inner peripheral face of the outer
peripheral side magnetic member and the side face of the drive
magnet which are faced each other are substantially parallel to
each other.
10. The lens drive device for use with at least one lens according
to claim 9, wherein a shape of the drive magnet when viewed in the
optical axis direction is substantially same as a shape of the
second end face side magnetic member when viewed in the optical
axis direction.
11. The lens drive device for use with at least one lens according
to claim 1, wherein a shape of the lens drive device when viewed in
the optical axis direction is formed in a substantially square
shape or a substantially rectangular shape, and the drive magnet is
disposed at four corners of the lens drive device.
12. The lens drive device for use with at least one lens according
to claim 11, wherein the drive magnet is formed in a substantially
triangular prism shape.
13. The lens drive device for use with at least one lens according
to claim 12, wherein the fixed body is provided with a cover member
which is formed in a substantially bottomed tube-like shape in
which the end face side magnetic member is a bottom part and the
outer peripheral side magnetic member is a tube part that is
integrally formed with the bottom part, and the end face side
magnetic member structures an end face on an object to be
photographed or imaged side of the lens drive device.
14. The lens drive device for use with at least one lens according
to claim 13, wherein the drive mechanism is provided with one drive
coil which is wound around in a tube-like shape and disposed along
the inner peripheral face of the outer peripheral side magnetic
member.
15. The lens drive device for use with at least one lens according
to claim 14, wherein the movable body is provided with a sleeve
which holds a lens holder to which the lens is fixed, the sleeve is
formed with two flange parts which are separated from each other in
the optical axis direction through a predetermined space, the
flange part which is disposed on a side of the end face side
magnetic member is formed with an arrangement hole within which a
part of the drive magnet is disposed, and the drive coil is fixed
between the two flange parts of the sleeve so as to be fixed on an
outer peripheral side of the arrangement hole.
16. The lens drive device for use with at least one lens according
to claim 13, wherein the drive mechanism is provided with four
drive coils each of which is wound around in a substantially
triangular tube-like shape and disposed so that an inner peripheral
face of the drive coil faces the side face of the drive magnet
through a predetermined gap space.
17. The lens drive device for use with at least one lens according
to claim 1, wherein a shape of the lens drive device when viewed in
the optical axis direction is formed in a substantially rectangular
shape, and the drive magnet is disposed on both sides of the lens
drive device in a direction substantially parallel to a long side
of the lens drive device when viewed in the optical axis
direction.
18. The lens drive device for use with at least one lens according
to claim 17, wherein the drive magnet is formed in a substantially
rectangular prism shape.
19. The lens drive device for use with at least one lens according
to claim 18, further comprising a second end face side magnetic
member which is formed of magnetic material and fixed to the other
end face of the drive magnet, wherein the drive coil is formed in a
tube-like shape so as to be movable between the side face of the
drive magnet and the inner peripheral face of the outer peripheral
side magnetic member, and wherein a width in the optical axis
direction of the drive coil is set to be a width in which the
second end face side magnetic member is always located on an inner
peripheral side of the drive coil over a moving range of the
movable body.
20. The lens drive device for use with at least one lens according
to claim 19, wherein the movable body is provided with a sleeve
which holds a lens holder to which the lens is fixed, and the drive
mechanism is provided with one drive coil which is fixed to the
sleeve and wound around in a substantially rectangular shape which
is longer in a long side direction of the lens drive device when
viewed in the optical axis direction.
21. The lens drive device for use with at least one lens according
to claim 19, wherein the movable body is provided with a sleeve
which holds a lens holder to which the lens is fixed, and the drive
mechanism is provided with two drive coils each of which is wound
around in a substantially rectangular tube shape when viewed in the
optical axis direction and fixed to the sleeve so that an inner
peripheral face of the drive coil faces the side face of the drive
magnet through a predetermined gap space.
Description
CROSS REFERENCE TO RELATED APPLICATION
[0001] The present invention claims priority under 35 U.S.C.
.sctn.119 to Japanese Application No. 2010-70526 filed Mar. 25,
2010, the entire content of which is incorporated herein by
reference.
FIELD OF THE INVENTION
[0002] At least an embodiment of the present invention may relate
to a lens drive device for use with at least one lens which is used
in a relatively small camera that is mounted on a cellular phone or
the like.
BACKGROUND
[0003] A lens drive device has been conventionally known in which a
photographing lens for a camera that is mounted on a cellular phone
or the like is driven. The lens drive device is provided with a
lens holder, which holds a plurality of lenses and is moved in an
optical axis direction, and a drive mechanism part for driving the
lens holder in the optical axis direction (see, for example,
Japanese Patent Laid-Open No. 2009-198948). In the lens drive
device described in this Patent Literature, a drive coil which is
wound around in a square shape is fixed to an outer peripheral side
of the lens holder and two drive magnets are disposed so as to
interpose the drive coil from both sides in the optical axis
direction.
[0004] In recent years, in a market of a camera which is mounted on
a cellular phone or the like, requirement for making a camera
thinner has been further increased and, in order to meet the
requirement, requirement for making a lens drive device used in a
camera thinner has been also increased. However, in the lens drive
device described in the above-mentioned Patent Literature, two
drive magnets are disposed so as to interpose the drive coil which
is fixed to the lens holder from both sides in the optical axis
direction. Therefore, when the device is made thinner, a space in
the optical axis direction between two drive magnets becomes
narrow. As a result, in the lens drive device, when the device is
made thinner, it is difficult to secure a required stroke of the
lens.
SUMMARY
[0005] In view of the problem described above, at least an
embodiment of the present invention may advantageously provide a
lens drive device which is capable of being made thinner in the
optical axis direction while securing a stroke of the lens.
[0006] According to at least an embodiment of the present
invention, there may be provided a lens drive device including a
movable body which holds a lens and is movable in an optical axis
direction of the lens, a fixed body which movably holds the movable
body in the optical axis direction, and a drive mechanism for
driving the movable body in the optical axis direction. The drive
mechanism includes a drive coil which is fixed to the movable body,
and a plurality of drive magnets which is formed in a substantially
columnar shape or a substantially plate shape and fixed to the
fixed body, and the drive magnet is magnetized so that a magnetic
pole of one end face is different from a magnetic pole of the other
end face in the optical axis direction. The fixed body includes an
outer peripheral side magnetic member, which is formed of magnetic
material and formed in a substantially tube-like shape and
structures an outer peripheral face of the fixed body, and an end
face side magnetic member which is formed of magnetic material and
to which the one end face of the drive magnet is fixed. An inner
peripheral face of the outer peripheral side magnetic member and a
side face of the drive magnet are faced each other through a
predetermined space. The outer peripheral side magnetic member, the
end face side magnetic member and the drive magnet are disposed so
that a magnetic field is formed so as to pass through the drive
magnet, the end face side magnetic member and the outer peripheral
side magnetic member and returned to the other end face of the
drive magnet from the inner peripheral face of the outer peripheral
side magnetic member, or returned to the inner peripheral face of
the outer peripheral side magnetic member from the other end face
of the drive magnet, and the drive coil is disposed between the
other end face side of the drive magnet and the inner peripheral
face of the outer peripheral side magnetic member.
[0007] In the lens drive device for use with at least one lens in
accordance with an embodiment of the present invention, an inner
peripheral face of the outer peripheral side magnetic member which
is formed in a substantially tube-like shape and structures an
outer peripheral face of the fixed body is disposed so as to face a
side face of the drive magnet which is formed in a substantially
columnar shape or a substantially plate shape through a
predetermined space and the drive coil is disposed between the
other end face side of the drive magnet in the optical axis
direction and the inner peripheral face of the outer peripheral
side magnetic member. Therefore, even when the movable body is
moved in the optical axis direction, the drive magnet and the drive
coil are not interfered with each other. Accordingly, even when the
lens drive device is made thinner in the optical axis direction, a
stroke of the movable body in the optical axis direction, in other
words, a stroke of the lens in the optical axis direction is
secured. In other words, in accordance with the embodiment of the
present invention, the lens drive device is made thinner while
securing a stroke of the lens.
[0008] In accordance with an embodiment of the present invention,
the outer peripheral side magnetic member and the end face side
magnetic member are formed in an integral manner. In this case, for
example, the fixed body is provided with a cover member which is
formed in a substantially bottomed tube-like shape in which the end
face side magnetic member is a bottom part and the outer peripheral
side magnetic member is a tube part that is integrally formed with
the bottom part, and the end face side magnetic member structures
an end face on an object to be photographed or imaged side of the
lens drive device. According to this structure, leakage of a
magnetic flux from a portion between the end face side magnetic
member and the outer peripheral side magnetic member is prevented.
Therefore, a magnetic flux density passing through the drive coil
which is disposed between the other end face side of the drive
magnet and the inner peripheral face of the outer peripheral side
magnetic member is enhanced. As a result, even when the drive
magnet and the drive coil are made thinner, a driving force of the
drive mechanism is secured and thus the lens drive device can be
further made thinner.
[0009] In accordance with an embodiment of the present invention,
an end face of the end face side magnetic member is abutted with
the inner peripheral face of the outer peripheral side magnetic
member. According to this structure, leakage of a magnetic flux
from a portion between the end face side magnetic member and the
outer peripheral side magnetic member is restrained and thus a
magnetic flux density passing through the drive coil is enhanced.
Therefore, even when the drive magnet and the drive coil are made
thinner, a driving force of the drive mechanism is secured.
[0010] In accordance with an embodiment of the present invention,
the inner peripheral face of the outer peripheral side magnetic
member and the side face of the drive magnet which are faced each
other are substantially parallel to each other. According to this
structure, directions of magnetic lines of force generated from the
drive magnet are easily directed from the other end face of the
drive magnet to the inner peripheral face of the outer peripheral
side magnetic member, or easily directed from the inner peripheral
face of the outer peripheral side magnetic member to the other end
face of the drive magnet and thus a magnetic flux density passing
through the drive coil is enhanced. Therefore, even when the drive
magnet and the drive coil are made thinner, a driving force of the
drive mechanism is secured.
[0011] In accordance with an embodiment of the present invention,
the other end face of the drive magnet is fixed with a second end
face side magnetic member which is formed of magnetic material, and
the magnetic field is directed from the inner peripheral face of
the outer peripheral side magnetic member to the other end face of
the drive magnet through the second end face side magnetic member,
or the magnetic field is directed from the other end face of the
drive magnet to the inner peripheral face of the outer peripheral
side magnetic member through the second end face side magnetic
member. When the second end face side magnetic member is fixed to
the other end face of the drive magnet, a magnetic flux is
concentrated on the second end face side magnetic member.
Therefore, according to this structure, a magnetic flux density
passing through the drive coil is enhanced. In this case, it is
preferable that a width in the optical axis direction of the drive
coil is set to be a width in which the second end face side
magnetic member is always located and faced on an inner peripheral
side of the drive coil over a moving range of the movable body.
[0012] In accordance with an embodiment of the present invention, a
shape of the drive magnet when viewed in the optical axis direction
is substantially the same as a shape of the second end face side
magnetic member when viewed in the optical axis direction. In
comparison with a case that a shape of the drive magnet when viewed
in the optical axis direction is different from a shape of the
second end face side magnetic member when viewed in the optical
axis direction, when the shape of the drive magnet when viewed in
the optical axis direction is substantially the same as the shape
of the second end face side magnetic member when viewed in the
optical axis direction, directions of magnetic lines of force
generated from the drive magnet are easily directed from the other
end face of the drive magnet to the inner peripheral face of the
outer peripheral side magnetic member, or easily directed from the
inner peripheral face of the outer peripheral side magnetic member
to the other end face of the drive magnet. Therefore, according to
this structure, a magnetic flux density passing through the drive
coil is further enhanced.
[0013] In accordance with an embodiment of the present invention,
the drive mechanism is provided with one drive coil which is wound
around in a tube-like shape and disposed along the inner peripheral
face of the outer peripheral side magnetic member. According to
this structure, in comparison with a case that a plurality of drive
coils is disposed so as to correspond to a plurality of drive
magnets, a structure of the lens drive device is simplified.
Further, according to this structure, in comparison with a case
that a plurality of drive coils is disposed, handling of end parts
of a conducting wire structuring the drive coil is simplified and
thus manufacturing steps for the lens drive device are simplified.
Specifically, it may be structured that the movable body is
provided with a sleeve which holds a lens holder to which the lens
is fixed, the sleeve is formed with two flange parts which are
separated from each other through a predetermined space in the
optical axis direction, the flange part which is disposed on a side
of the end face side magnetic member is formed with an arrangement
hole within which a part of the drive magnet is disposed, and the
drive coil is fixed between the two flange parts of the sleeve so
as to be fixed on an outer peripheral side of the arrangement
hole.
[0014] In accordance with an embodiment of the present invention, a
shape of the lens drive device when viewed in the optical axis
direction is formed in a substantially square shape or a
substantially rectangular shape, and the drive magnet is disposed
at four corners of the lens drive device. In this case, the drive
magnet may be disposed at four corners of the lens drive device
which is liable to be dead spaces. Therefore, the size of the lens
drive device whose shape when viewed in the optical axis direction
is formed in a substantially square shape or a substantially
rectangular shape can be reduced.
[0015] Further, in this case, it is preferable that the drive
magnet is formed in a substantially triangular prism shape.
According to this structure, even when spaces of four corners of
the lens drive device are made relatively small, the drive magnet
is disposed at four corners of the lens drive device. Therefore,
the size of the lens drive device can be further reduced. Further,
according to this structure, the inner peripheral face of the outer
peripheral side magnetic member and the side face of the drive
magnet can be disposed to be substantially parallel to each other
and thus, as described above, a magnetic flux density passing
through the drive coil can be enhanced. In this case, the drive
mechanism may be provided with one drive coil which is wound around
in a tube-like shape and disposed along the inner peripheral face
of the outer peripheral side magnetic member, or the drive
mechanism may be provided with four drive coils each of which is
wound around in a substantially triangular tube-like shape and
faces the side face of the drive magnet through a predetermined gap
space.
[0016] In accordance with an embodiment of the present invention, a
shape of the lens drive device for use with at least one lens when
viewed in the optical axis direction is formed in a substantially
rectangular shape, and the drive magnet is disposed on both sides
of the lens drive device in a direction substantially parallel to a
long side of the lens drive device when viewed in the optical axis
direction. In this case, the size of the lens drive device is
further reduced in a direction substantially parallel to a short
side of the lens drive device when viewed in the optical axis
direction.
[0017] Further, in this case, it is preferable that the drive
magnet is formed in a substantially rectangular prism shape.
According to this structure, the inner peripheral face of the outer
peripheral side magnetic member and the side face of the drive
magnet can be disposed to be substantially parallel to each other
and thus, as described above, a magnetic flux density passing
through the drive coil can be enhanced. In this case, specifically,
it may be structured that the movable body is provided with a
sleeve which holds a lens holder to which the lens is fixed, and
the drive mechanism is provided with one drive coil which is fixed
to the sleeve and wound around in a substantially rectangular shape
which is longer in a long side direction of the lens drive device
when viewed in the optical axis direction. Alternatively, the drive
mechanism may be provided with two drive coils each of which is
wound around in a substantially rectangular tube shape when viewed
in the optical axis direction and fixed to the sleeve so that an
inner peripheral face of the drive coil faces the side face of the
drive magnet through a predetermined gap space.
[0018] Other features and advantages of the invention will be
apparent from the following detailed description, taken in
conjunction with the accompanying drawings that illustrate, by way
of example, various features of embodiments of the invention.
BRIEF DESCRIPTION OF THE DRAWINGS
[0019] Embodiments will now be described, by way of example only,
with reference to the accompanying drawings which are meant to be
exemplary, not limiting, and wherein like elements are numbered
alike in several Figures, in which:
[0020] FIG. 1 is a perspective view showing a lens drive device for
use with at least one lens in accordance with an embodiment of the
present invention.
[0021] FIG. 2 is a cross-sectional view showing the lens drive
device for use with at least one lens which is cut by the "E-E"
line in FIG. 1.
[0022] FIG. 3 is an exploded perspective view showing the lens
drive device for use with at least one lens in FIG. 1.
[0023] FIG. 4 is a plan view showing the lens drive device for use
with at least one lens in FIG. 1 from which a movable body, a flat
spring, a base member and the like are detached and which is viewed
from an opposite-to-object side.
[0024] FIG. 5 is a cross-sectional view showing the "G-G" cross
section in FIG. 4 where an object to be photographed or imaged side
is located on an upper side.
[0025] FIG. 6 is an explanatory view showing a structure of a drive
coil in accordance with another embodiment of the present
invention.
[0026] FIGS. 7(A) and 7(B) are explanatory views showing a
schematic structure of a lens drive device for use with at least
one lens in accordance with another embodiment of the present
invention. FIG. 7(A) is an explanatory view showing a schematic
structure of the lens drive device which is viewed from an
opposite-to-object side and FIG. 7(B) is a cross-sectional view
showing the "H-H" cross section in FIG. 7(A) where an object to be
photographed or imaged side is located on an upper side.
[0027] FIG. 8 is an explanatory view showing a schematic structure
of a lens drive device for use with at least one lens in accordance
with another embodiment of the present invention which is viewed
from an opposite-to-object side.
[0028] FIGS. 9(A) and 9(B) are explanatory views showing a
schematic structure of a lens drive device for use with at least
one lens in accordance with another embodiment of the present
invention. FIG. 9(A) is an explanatory view showing a schematic
structure of the lens drive device which is viewed from an
opposite-to-object side and FIG. 9(B) is a cross-sectional view
showing the "J-J" cross section in FIG. 9(A) where an object to be
photographed or imaged side is located on an upper side.
[0029] FIG. 10 is an enlarged sectional view showing a part of a
lens drive device for use with at least one lens in accordance with
another embodiment of the present invention.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0030] An embodiment of the present invention will be described
below with reference to the accompanying drawings.
[0031] FIG. 1 is a perspective view showing a lens drive device for
use with at least one lens 1 in accordance with an embodiment of
the present invention. FIG. 2 is a cross-sectional view showing the
lens drive device 1 which is cut by the "E-E" line in FIG. 1. FIG.
3 is an exploded perspective view showing the lens drive device 1
in FIG. 1. In the following description, as shown in FIG. 1 and the
like, three directions perpendicular to each other are set to be
"X" direction, "Y" direction and "Z" direction. The "X" direction
is a right and left direction, the "Y" direction is a front and
rear direction, and the "Z" direction is an up-and-down direction.
Further, a "Z1" direction side in FIG. 1 is an "upper" side and a
"Z2" direction side is a "lower" side.
[0032] A lens drive device 1 for use with at least one lens in this
embodiment is mounted on a relatively small camera which is used in
a cellular phone, a drive recorder, a monitor camera system or the
like. The lens drive device 1 is, as shown in FIG. 1, formed in a
roughly rectangular prism shape as a whole. In other words, the
lens drive device 1 is formed in a roughly rectangular shape when
viewed in a direction of an optical axis "L" of a lens for
photography or imaging including digital images and video for
example (optical axis direction). In this embodiment, the lens
drive device 1 is formed in a roughly square shape when viewed in
the optical axis direction. Further, four side faces of the lens
drive device 1 are substantially parallel to the right and left
direction or the front and rear direction.
[0033] In this embodiment, the "Z" direction (up-and-down
direction) is substantially coincided with the optical axis
direction. Further, in the camera on which the lens drive device 1
in this embodiment is mounted, an imaging element not shown is
disposed on its lower side and an object to be photographed or
imaged on an upper side is photographed or imaged. In other words,
in this embodiment, the upper side ("Z1" direction side) is an
object to be photographed or imaged side (object side) and the
lower side ("Z2" direction side) is an opposite-to-object side
(imaging element side, image side).
[0034] As shown in FIGS. 1 and 2, the lens drive device 1 is
provided with a movable body 2, which holds a lens for photography
or imaging and is movable in the optical axis direction, a fixed
body 3 which movably holds or moveable mounts the movable body 2 in
the optical axis direction so that the moveable body 2 may move in
relation to the fixed body 3 in the optical axis direction, and a
drive mechanism 4 for driving the movable body 2 in the optical
axis direction. The movable body 2 is movably held by the fixed
body 3 through flat springs 5 and 6 (see FIG. 2). In FIG. 3, the
flat springs 5 and 6 are not shown.
[0035] The movable body 2 is provided with a sleeve 8 which holds a
lens holder 7 to which at least one lens or a plurality of lenses
is fixed. The fixed body 3 is provided with a cover member 10 which
structures four side faces (outer peripheral face) of the lens
drive device 1 and a base member 11 which structures an end face on
an opposite-to-object side of the lens drive device 1. In FIG. 3,
the lens holder 7 is not shown.
[0036] The lens holder 7 is formed in a substantially cylindrical
tube shape having a stepped part. The at least one or a plurality
of lenses whose shape when viewed in the optical axis direction is
substantially circular is fixed on an inner peripheral side of the
lens holder 7. The sleeve 8 is, for example, formed of resin
material and formed in roughly tube-like shape. The sleeve 8 holds
the lens holder 7 on its inner peripheral side. In other words, an
outer peripheral face of the lens holder 7 is fixed to an inner
peripheral face of the sleeve 8. Further, the sleeve 8 is formed
with two flange parts 8a and 8b in a separated state from each
other through a predetermined space in the up-and-down direction as
shown in FIG. 3. The flange parts 8a and 8b are formed so that
their external shapes are formed in a substantially square shape.
The flange part 8a disposed on the upper side is formed with
arrangement holes 8c within which parts of drive magnets 15
structuring the drive mechanism 4 are disposed are formed so as to
penetrate in the up-and-down direction.
[0037] The cover member 10 is formed of magnetic material and
formed in a substantially rectangular tube shape with a bottom
(substantially bottomed rectangular tube shape) which is provided
with a bottom part 10a and a tube part 10b. The bottom part 10a is
disposed on the upper side and structures an end face on the object
to be photographed or imaged side of the lens drive device 1. A
circular through hole 10c is formed at a center of the bottom part
10a. The cover member 10 is disposed so as to surround an outer
peripheral side of the drive mechanism 4 and the movable body
2.
[0038] The base member 11 is formed of resin material and provided
with a base part 11a which is formed in a roughly square-shaped
flat plate and standing-up parts 11b which are stood up toward the
upper side from four corners of the base part 11a. A circular
through hole 11c is formed at a center of the base part 11a. The
base member 11 is attached to a lower end side of the cover member
10.
[0039] The flat springs 5 and 6 are structured of a movable body
side fixing part which is fixed to the sleeve 8, fixed body side
fixing parts which are fixed to the standing-up parts 11b of the
base member 11, and spring parts which connect the movable body
side fixing part with the fixed body side fixing parts. The flat
springs 5 and 6 are disposed on a lower side with respect to the
flange part 8b disposed on the lower side. In this embodiment, the
flat spring 5 is fixed to the sleeve 8, i.e., the under face of the
flange part 8b and the base member 11 in a resiliently bent state
so that, when an electric current is not supplied to the drive coil
16, a reference face formed on an upper face of the base part 11a
and a lower end face of the sleeve 8 are abutted with each other
and the movable body 2 is located at a predetermined reference
position.
[0040] The drive mechanism 4 is provided with four drive magnets 15
in a substantially triangular prism shape which are disposed at
four corners of the lens drive device 1 (specifically, four corners
on the inner side of the cover member 10) and one drive coil 16
which is wound around on an outer peripheral side of the sleeve 8.
A detailed structure of the drive mechanism 4 will be described
below.
[0041] FIG. 4 is a plan view showing the lens drive device 1 in
FIG. 1 from which the movable body 2, the flat springs 5 and 6, the
base member 11 and the like are detached and which is viewed from
an opposite-to-object side. FIG. 5 is a cross-sectional view
showing the "G-G" cross section in FIG. 4 where an object to be
photographed or imaged side is located on an upper side.
[0042] The drive magnet 15 is formed so that its shape when viewed
in the up-and-down direction is a substantially rectangular
equilateral triangle. The drive magnet 15 is provided with two
first side faces (first side face) 15a which are formed in a
rectangular shape and are substantially parallel to the optical
axis "L" and perpendicular to each other, and one second side face
(second side face) 15b which is formed in a rectangular shape,
substantially parallel to the optical axis "L" and connected with
the two first side faces 15a.
[0043] The drive magnet 15 is disposed so that its first side face
15a faces an inner peripheral face of the tube part 10b of the
cover member 10 through a predetermined space so as to be
substantially parallel to each other. In other words, two drive
magnets 15 which are disposed at diagonal positions on the inner
side of the cover member 10 are disposed so that their second side
faces 15b are faced each other. Further, four drive magnets 15 are
fixed to the bottom part 10a of the cover member 10. Specifically,
upper end faces of the four drive magnets 15 are fixed to an under
face of the bottom part 10a by an adhesive or the like in a state
that their upper end faces are abutted with the under face of the
bottom part 10a. Further, the upper end face of each of the four
drive magnets 15 is completely covered by the bottom part 10a. The
bottom part 10a in this embodiment is an end face side magnetic
member to which one end face of each of the drive magnets 15 is
fixed, and the tube part 10b is an outer peripheral side magnetic
member which structures the outer peripheral face of the fixed body
3.
[0044] A lower end face of the drive magnet 15 is fixed with a
magnetic member 17 which is formed of magnetic material. The
magnetic member 17 is formed in a flat plate shape whose shape when
viewed in the up-and-down direction is in a substantially
rectangular equilateral triangle shape that is similarly to the
drive magnet 15. The magnetic member 17 is provided with two first
end faces (first end face) 17a perpendicular to each other and one
second end face (second end face) 17b which is connected with the
two first end faces 17a. The magnetic member 17 is fixed to the
lower end face of the drive magnet 15 so that its thickness
direction is substantially coincided with the up-and-down
direction. Further, the magnetic member 17 is fixed to the lower
end face of the drive magnet 15 so that the first end faces 17a are
disposed to be substantially the same flat faces as the first side
faces 15a of the drive magnet 15 and the second end face 17b is
disposed to be substantially the same flat face as the second side
face 15b of the drive magnet 15. The magnetic member 17 in this
embodiment is a second end face side magnetic member which is fixed
to the other end face of the drive magnet 15.
[0045] The drive magnet 15 is magnetized in two poles in the
up-and-down direction so that a magnetic pole of the upper end face
and a magnetic pole of the lower end face are different from each
other. For example, the drive magnet 15 is magnetized such that the
upper end face of the drive magnet 15 is an "S"-pole and the lower
end face of the drive magnet 15 is an "N"-pole. Therefore, as shown
in FIG. 5, in the lens drive device 1, a magnetic field "F" is
formed which passes the tube part 10b and the bottom part 10a of
the cover member 10, the drive magnet 15 and the magnetic member 17
to be returned to the inner peripheral face of the tube part 10b
from the under face and the first end face 17a of the magnetic
member 17. In other words, in the lens drive device 1, a magnetic
field "F" is formed which passes the tube part 10b and the bottom
part 10a of the cover member 10 and the drive magnet 15 to be
returned from the lower end face of the drive magnet 15 to the
inner peripheral face of the tube part 10b through the magnetic
member 17. The magnetic field "F" is, as shown in FIG. 4, returned
to the inner peripheral face of the tube part 10b, which is
disposed to be substantially parallel to the first side face 15a of
the drive magnet 15 and the first end face 17a of the magnetic
member 17, from the under face and the first end face 17a of the
magnetic member 17. The magnetic field "F" is also returned to the
inner peripheral face of the tube part 10b from the vicinity of the
abutting part of the lower end face of the drive magnet 15 with the
upper face of the magnetic member 17 but the magnetic field "F" is
not shown in FIG. 5.
[0046] The drive coil 16 is wound around in a flat and
substantially rectangular tube shape whose shape viewed in the
up-and-down direction is a substantially square shape. A width of
the drive coil 16 in the up-and-down direction is wider than a
thickness of the magnetic member 17. The drive coil 16 is fixed to
the outer peripheral face of the sleeve 8. Specifically, the drive
coil 16 is fixed between the flange parts 8a and 8b of the sleeve 8
and disposed on an outer peripheral side of the arrangement hole 8c
provided in the flange part 8a by adhesion or the like.
[0047] The drive coil 16 is, as shown in FIG. 4, disposed along the
inner peripheral face of the tube part 10b of the cover member 10.
Four corners and their vicinity portions of the drive coil 16 are
disposed within a space between the first side face 15a of the
drive magnet 15 and the first end face 17a of the magnetic member
17 and the tube part 10b of the cover member 10. Further, as shown
in FIG. 5, the four corners and their vicinity portions of the
drive coil 16 are disposed in the magnetic field "F" which is
directed from the under face and the first end face 17a of the
magnetic member 17 to the inner peripheral face of the tube part
10b. In this embodiment, the drive coil 16 is disposed so that the
magnetic member 17 is always disposed on the inner peripheral side
of the drive coil 16 over a moving range of the movable body 2. In
other words, a width in the up-and-down direction (optical axis
direction) of the drive coil 16 is set so that, over the moving
range of the movable body 2, the lower end face of the drive coil
16 is not moved to the upper side with respect to the under face of
the magnetic member 17 and, in addition, the upper end face of the
drive coil 16 is not moved to the lower side with respect to the
upper face of the magnetic member 17. When an electric current is
supplied to the drive coil 16, the movable body 2 is moved in the
up-and-down direction (optical axis direction) by an operation
between the drive magnets 15 and the drive coil 16.
[0048] As described above, in this embodiment, the four corners and
their vicinity portions of the drive coil 16 are disposed within a
space between the first side face 15a of the drive magnet 15 and
the first end face 17a of the magnetic member 17 and the tube part
10b of the cover member 10. Therefore, even when the movable body 2
is moved in the optical axis direction, the drive magnets 15 and
the drive coil 16 are not interfered with each other. Accordingly,
in this embodiment, even when the lens drive device 1 is made
thinner in the up-and-down direction, a stroke of the lens held by
the movable body 2 is secured. In other words, in this embodiment,
the lens drive device 1 can be made thinner while securing a stroke
of the lens.
[0049] In this embodiment, the bottom part 10a with which the upper
end face of the drive magnet 15 is abutted is integrally formed
with the tube part 10b. Therefore, magnetic flux is prevented from
leaking out from a portion between the bottom part 10a and the tube
part 10b to the outside of the lens drive device 1. Further, in
this embodiment, the first side face 15a of the drive magnet 15 is
substantially parallel to the inner peripheral face of the tube
part 10b. Therefore, directions of the magnetic lines of force
which are generated by the drive magnet 15 are easily directed to
the directions from the under face and the first end face 17a of
the magnetic member 17 toward the inner peripheral face of the tube
part 10b. Accordingly, in this embodiment, the magnetic flux
density which is directed from the under face and the first end
face 17a of the magnetic member 17 to the inner peripheral face of
the tube part 10b, (in other words, magnetic flux density passing
through the drive coil 16) is enhanced. As a result, in this
embodiment, even when the drive magnet 15 and the drive coil 16 are
made thinner, a driving force of the drive mechanism 4 is secured
and thus the lens drive device 1 can be further made thinner.
[0050] Especially, in this embodiment, the magnetic member 17 is
fixed to the lower end face of the drive magnet 15 and the shape of
the drive magnet 15 and the shape of the magnetic member 17 are
substantially the same as each other when viewed in the up-and-down
direction. According to consideration of the present inventors,
when the magnetic member 17 is fixed to the lower end face of the
drive magnet 15, a magnetic flux is concentrated on the magnetic
member 17. Further, according to consideration of the present
inventors, when the shape of the drive magnet 15 and the shape of
the magnetic member 17 viewed in the up-and-down direction are
different from each other, directions of the magnetic lines of
force which are generated from the drive magnet 15 are hard to be
directed from the under face and the first end face 17a of the
magnetic member 17 to the inner peripheral face of the tube part
10b. However, when the shape of the drive magnet 15 and the shape
of the magnetic member 17 viewed in the up-and-down direction are
substantially the same as each other, directions of the magnetic
lines of force which are generated from the drive magnet 15 are
easily directed from the under face and the first end face 17a of
the magnetic member 17 to the inner peripheral face of the tube
part 10b. Therefore, in this embodiment, the density of the
magnetic flux which is directed to the inner peripheral face of the
tube part 10b from the under face and the first end face 17a of the
magnetic member 17 is enhanced effectively. As a result, in this
embodiment, even when the drive magnet 15 and the drive coil 16 are
further made thinner, a driving force of the drive mechanism 4 can
be secured.
[0051] In this embodiment, the four corners and their vicinity
portions of the drive coil 16 are disposed in the magnetic field
"F" which is directed from the under face and the first end face
17a of the magnetic member 17 to the inner peripheral face of the
tube part 10b. Therefore, even when the movable body 2 is moved to
the upper direction from the reference position where the lower end
face of the sleeve 8 is abutted with the reference face which is
formed on the upper face of the base member 11, a driving force of
the drive mechanism 4 is hard to be lowered. Accordingly, in this
embodiment, the movable body 2 can be moved relatively larger from
the reference position to the upper direction by a driving force of
the drive mechanism 4. As a result, in this embodiment, a stroke of
the lens is easily secured and a stable driving force of the drive
mechanism 4 can be obtained over a stroke of the lens.
[0052] In this embodiment, the drive magnets 15 are disposed at
four corners of the lens drive device 1 whose shape viewed in the
optical axis direction is a substantially square shape. Therefore,
the drive magnets 15 can be disposed at four corners of the lens
drive device 1 which may be dead spaces in the lens drive device 1
that drives the lens whose shape viewed in the optical axis
direction is a substantially circular shape. Further, in this
embodiment, the drive magnet 15 is formed in a substantially
triangular prism shape. Therefore, even when spaces of the four
corners of the lens drive device 1 are set to be reduced, the drive
magnets 15 can be disposed. Accordingly, in this embodiment, the
size of the lens drive device 1 can be reduced.
First Modified Embodiment of Lens Drive Device
[0053] FIG. 6 is an explanatory view showing a structure of a drive
coil 26 in accordance with another embodiment of the present
invention.
[0054] In the embodiment described above, the drive mechanism 4 is
provided with one drive coil 16 which is disposed along the inner
peripheral face of the tube part 10b of the cover member 10.
However, the drive mechanism 4 may be provided, instead of the
drive coil 16, with four drive coils 26 as shown in FIG. 6, each of
which is wound around in a substantially triangular tube-like shape
and its inner peripheral face is disposed so as to face the side
face of the drive magnet 15 through a predetermined gap space. In
the first modified embodiment, the drive coil 26 is wound around so
that its shape viewed in the up-and-down direction is a
substantially rectangular equilateral triangle shape. Further, four
drive coils 26 are fixed to the sleeve 8 so that the inner
peripheral face of the drive coil 26 and the side face of the drive
magnet 15 are substantially parallel to each other with a
predetermined gap space therebetween.
[0055] Even in the first modified embodiment, effects similar to
the above-mentioned embodiment can be obtained. Further, in the
first modified embodiment, magnetic flux on the second end face 17b
side is utilized for driving of the movable body 2 and thus a
driving force of the drive mechanism 4 is further enhanced. In the
embodiment described above, only one drive coil 16 is utilized and
thus, in comparison with the first modified embodiment, the
structure of the lens drive device 1 is simplified. Further, in
comparison with the first modified embodiment, in the embodiment
described above, end parts of a conducting wire of only one drive
coil 16 are required to be handled and thus handling of end parts
of a conducting wire structuring the drive coil 16 is simplified.
Therefore, manufacturing steps for the lens drive device 1 can be
simplified.
Second Modified Embodiment of Lens Drive Device
[0056] FIGS. 7(A) and 7(B) are explanatory views showing a
schematic structure of a lens drive device 1 in accordance with
another embodiment of the present invention. FIG. 7(A) is an
explanatory view showing a schematic structure of the lens drive
device 1 which is viewed from an opposite-to-object side and FIG.
7(B) is a cross-sectional view showing the "H-H" cross section in
FIG. 7(A) where an object to be photographed or imaged side is
located on an upper side. FIG. 8 is an explanatory view showing a
schematic structure of a lens drive device 1 in accordance with
another embodiment of the present invention which is viewed from an
opposite-to-object side.
[0057] In the embodiment described above, the lens drive device 1
is formed so that its shape viewed in the optical axis direction is
a substantially square shape. Further, the drive magnet 15 formed
in a substantially triangular prism shape is disposed at four
corners of the lens drive device 1. However, the present invention
is not limited to this embodiment. For example, the lens drive
device 1 may be formed so that its shape viewed in the optical axis
direction is a substantially rectangular shape. Further, in this
case, as shown in FIG. 7(A), a drive magnet 35 may be formed in a
substantially rectangular prism shape and disposed on both sides of
the lens drive device in a direction substantially parallel to a
long side of the lens drive device 1 when viewed in the optical
axis direction. The lens drive device 1 in accordance with the
second modified embodiment is provided with a sleeve 38
corresponding to the sleeve 8 of the embodiment described above and
a cover member 30 corresponding to the cover member 10.
[0058] The drive magnet 35 is formed in a substantially rectangular
shape whose shape viewed in the up-and-down direction is elongated
in a short side direction of the lens drive device 1. The drive
magnet 35 is disposed so that its three side faces 35a and an inner
peripheral face of the tube part 30b of the cover member 30 are
substantially parallel and faced to each other with a predetermined
space therebetween. Further, the drive magnet 35 is fixed to an
under face of the bottom part 30a of the cover member 30 in an
abutted state. A lower end face of the drive magnet 35 is fixed to
a magnetic member 37 which is formed of magnetic material. The
magnetic member 37 is formed in a flat plate-like shape whose shape
viewed in the up-and-down direction is a substantially rectangular
shape that is similar to the drive magnet 35. In the second
modified embodiment, the bottom part 30a is an end face side
magnetic member to which one end face of the drive magnet 35 is
fixed and the tube part 30b is an outer peripheral side magnetic
member which structures an outer peripheral face of the fixed body
3. Further, the magnetic member 37 is a second end face side
magnetic member which is fixed to the other end face of the drive
magnet 35.
[0059] The drive magnet 35 is magnetized in two poles in the
up-and-down direction so that a magnetic pole of the upper end face
and a magnetic pole of the lower end face are different from each
other. Therefore, as shown in FIG. 7(B), in the lens drive device 1
in accordance with the second modified embodiment, a magnetic field
"F" is formed which passes the tube part 30b and the bottom part
30a of the cover member 30, the drive magnet 35 and the magnetic
member 37 to be returned to the inner peripheral face of the tube
part 30b from the under face and the end face of the magnetic
member 37. In other words, in the lens drive device 1 in accordance
with the second modified embodiment, a magnetic field "F" is formed
which passes the tube part 30b and the bottom part 30a of the cover
member 30 and the drive magnet 35 to be returned from the lower end
face of the drive magnet 35 to the inner peripheral face of the
tube part 30b through the magnetic member 37. The magnetic field
"F" is, as shown in FIG. 7(A), directed from the under face and the
end face of the magnetic member 37 to the inner peripheral face of
the tube part 30b which is disposed so as to be substantially
parallel and faced to the three side faces 35a of the drive magnet
35. Similarly to the above-mentioned embodiment, the magnetic field
"F" is also returned to the inner peripheral face of the tube part
30b from the vicinity of abutting part of the lower end face of the
drive magnet 35 with the upper face of the magnetic member 37.
[0060] A drive coil 36 is wound around so that its shape viewed in
the up-and-down direction is a substantially rectangular shape
which is elongated in a long side direction of the lens drive
device 1. The drive coil 36 is provided with short side parts 36a
and long side parts 36b which are longer than the short side part
36a. The drive coil 36 is fixed to an outer peripheral face of the
sleeve 38 so as to be along the inner peripheral face of the tube
part 30b. Both end sides of the long side parts 36b and the short
side part 36a of the drive coil 36 are disposed within a space
between three side faces 35a of the drive magnet 35 and the inner
peripheral face of the tube part 30b. Further, the both end sides
of the long side parts 36b and the short side part 36a are disposed
within the magnetic field "F" which is directed from the under face
and the end faces of the magnetic member 37 to the inner peripheral
face of the tube part 30b.
[0061] Also in the lens drive device 1 in accordance with the
second modified embodiment, effects similar to the above-mentioned
embodiment can be obtained. Further, in the lens drive device 1 in
accordance with the second modified embodiment, the drive magnets
35 are disposed on both sides of the lens drive device 1 in a
direction substantially parallel to the long side of the lens drive
device 1 when viewed in the optical axis direction. Therefore, the
size of the lens drive device 1 can be further reduced in a
direction substantially parallel to the short side of the lens
drive device 1 when viewed in the optical axis direction. In
accordance with an embodiment of the present invention, instead of
the drive coil 36, as shown in FIG. 8, it may be structured that
two drive coils 46 which are wound around in a substantially
rectangular tube shape and whose inner peripheral side is disposed
so as to face the side face of the drive magnet 35 through a
predetermined space are fixed to an outer peripheral face of the
sleeve 38.
Third Modified Embodiment of Lens Drive Device
[0062] FIGS. 9(A) and 9(B) are explanatory views showing a
schematic structure of a lens drive device 1 in accordance with
another embodiment of the present invention. FIG. 9(A) is an
explanatory view showing a schematic structure of the lens drive
device 1 which is viewed from an opposite-to-object side and FIG.
9(B) is a cross-sectional view showing the "J-J" cross section in
FIG. 9(A) where an object to be photographed or imaged side is
located on an upper side.
[0063] In the embodiment described above, the drive magnet 15 which
is formed in a substantially triangular prism shape is disposed at
four corners of the lens drive device 1. However, the present
invention is not limited to this embodiment. For example, as shown
in FIG. 9(A), a drive magnet 55 which is formed in a substantially
rectangular plate shape may be disposed on each of four side faces
of the lens drive device 1.
[0064] In the third modified embodiment, the drive magnet 55 is
disposed so that its one side face 55a and an inner peripheral face
of a tube part 10b of a cover member 10 are in substantially
parallel and faced to each other with a predetermined space
therebetween. Further, the drive magnet 55 is fixed to an under
face of a bottom part 10a of the cover member 10 in an abutted
state. A lower end face of the drive magnet 55 is fixed to a
magnetic member 57 which is formed of magnetic material. The
magnetic member 57 is formed in a flat plate-like shape which is,
similarly to the drive magnet 55, substantially rectangular shape
when viewed in the up-and-down direction. In the third modified
embodiment, the magnetic member 57 is a second end face side
magnetic member which is fixed to the other end face of the drive
magnet 55.
[0065] The drive magnet 55 is magnetized in two poles in the
up-and-down direction so that a magnetic pole of the upper end face
and a magnetic pole of the lower end face are different from each
other. Therefore, similarly to the above-mentioned embodiment, in
the lens drive device 1 in accordance with the third modified
embodiment, a magnetic field "F" is formed which passes the tube
part 10b and the bottom part 10a, the drive magnet 55 and the
magnetic member 57 to be returned to the inner peripheral face of
the tube part 10b from the under face and the end face of the
magnetic member 57. The magnetic field "F" is, as shown in FIG.
9(A), directed from the under face and the end face of the magnetic
member 57 to the inner peripheral face of the tube part 10b which
is disposed so as to be substantially parallel and faced to the
side face 55a of the drive magnet 55. Similarly to the
above-mentioned embodiment, the magnetic field "F" is also returned
to the inner peripheral face of the tube part 10b from the vicinity
of abutting part of the lower end face of the drive magnet 55 with
the upper face of the magnetic member 57.
[0066] A part of the drive coil 16 is disposed within a space
between the side face 55a of the drive magnet 55 and the inner
peripheral face of the tube part 10b. Further, the part of the
drive coil 16 is disposed in the magnetic field "F" which is
directed from the under face and the end face of the magnetic
member 57 to the inner peripheral face of the tube part 10b. Also
in the third modified embodiment, effects similar to the
above-mentioned embodiment can be obtained.
Fourth Modified Embodiment of Lens Drive Device
[0067] FIG. 10 is an enlarged sectional view showing a part of a
lens drive device 1 in accordance with another embodiment of the
present invention.
[0068] In the embodiment described above, the upper end face of the
drive magnet 15 is fixed to the under face of the bottom part 10a
in an abutted state with the under face of the bottom part 10a.
However, the present invention is not limited to this embodiment.
For example, as shown in FIG. 10, a magnetic member 67 may be
formed so that an end face 67a of the magnetic member 67 which is
fixed to a lower end face of the drive magnet 15 is abutted with an
inner peripheral face of a tube part 72 of a cover member 70. In
this case, the end face 67a is fixed to the inner peripheral face
of the tube part 72 and a space is formed between an upper end face
of the drive magnet 15 and a bottom part 71 of the cover member
70.
[0069] In the fourth modified embodiment, a magnetic field "F"
which is directed from the inner peripheral face of the tube part
72 to an upper end face of the drive magnet 15 is formed and thus
four corners and their vicinity portions of the drive coil 16 are
disposed in the magnetic field "F" which is directed from the inner
peripheral face of the tube part 72 to the upper end face of the
drive magnet 15. Further, in the fourth modified embodiment, the
cover member 70 may be preferably structured of a bottom part 71
made of nonmagnetic material and a tube part 72 made of magnetic
material so that magnetic lines of force generated from the drive
magnet 15 are not directed from the bottom part 71 to the upper end
face of the drive magnet 15. In this embodiment, the lens drive
device 1 may be provided with four magnetic members 67 to which
respective four drive magnets 15 are fixed, or one magnetic member
67 to which all of four drive magnets 15 are fixed. Also in the
fourth modified embodiment, effects similar to the above-mentioned
embodiment can be obtained.
[0070] In the fourth modified embodiment, the magnetic member 67 is
an end face side magnetic member to which one end face of the drive
magnet 15 is fixed, and the tube part 72 is an outer peripheral
side magnetic member which structures the outer peripheral face of
the fixed body 3. Further, in the fourth modified embodiment, a
magnetic member is not fixed to the upper end face of the drive
magnet 15 but a magnetic member may be fixed to the upper end face
of the drive magnet 15. In this case, the magnetic member is a
second end face side magnetic member.
Other Embodiments
[0071] In the embodiment described above, the magnetic member 17 is
fixed to the lower end face of the drive magnet 15 but no magnetic
member 17 is fixed to the lower end face of the drive magnet 15. In
this case, a length of the drive magnet 15 is capable of being
increased in the up-and-down direction by a thickness of the
magnetic member 17 and thus a driving force of the drive mechanism
4 can be enhanced. Further, in this case, the magnetic member 17 is
not required to be fixed to a lower end face of the drive magnet 15
and thus assembling steps for the lens drive device 1 can be
simplified.
[0072] In the embodiment described above, the cover member 10 is
structured of the bottom part 10a and the tube part 10b, and the
bottom part 10a and the tube part 10b are formed in an integral
manner. However, the present invention is not limited to this
embodiment. For example, the bottom part made of magnetic material
and the tube part made of magnetic material may be formed of
separate members. In this case, the end face of the bottom part and
the inner peripheral face of the tube part may be abutted with each
other, or a gap space may be formed between the end face of the
bottom part and the inner peripheral face of the tube part.
Further, the under face of the bottom part and the upper end face
of the tube part may be abutted with each other, or a gap space may
be formed between the under face of the bottom part and the upper
end face of the tube part. However, in order to restrain leakage of
magnetic flux from a portion between the bottom part and the tube
part to enhance magnetic flux density passing through the drive
coil 16, it is preferable that the end face of the bottom part and
the inner peripheral face of the tube part are abutted with each
other, or the under face of the bottom part and the upper end face
of the tube part are abutted with each other.
[0073] In the embodiment described above, the drive magnet 15 is
formed in a substantially triangular prism shape, but the drive
magnet 15 may be formed in a polygonal prism shape other than a
substantially triangular prism shape or may be formed in a
substantially circular cylinder shape or a substantially elliptical
cylinder shape. Further, in the embodiment described above, the
lens drive device 1 is formed in a roughly quadrangular shape when
viewed in the optical axis direction. However, the lens drive
device 1 may be formed in a roughly polygonal shape other than a
roughly rectangular shape when viewed in the optical axis direction
or may be formed in a roughly circular shape or elliptical shape
when viewed in the optical axis direction. In these cases, the
drive coil 16 may be wound around, for example, in a cylindrical
tube shape or the like depending on the shape of the lens drive
device 1 and the shape of the drive magnet 15 when viewed in the
optical axis direction. Further, the drive coil 26 in the first
modified embodiment may be also wound around, for example, in a
cylindrical tube shape or the like depending on the shape of the
lens drive device 1 and the shape of the drive magnet 15 when
viewed in the optical axis direction.
[0074] In the embodiment described above, the shape of the drive
magnet 15 when viewed in the up-and-down direction is substantially
the same as the shape of the magnetic member 17. However, the shape
of the drive magnet 15 when viewed in the up-and-down direction may
be different from the shape of the magnetic member 17. Further, in
the embodiment described above, the drive magnet 15 is disposed at
four corners of the lens drive device 1. However, when a sufficient
driving force for the movable body 2 is obtained, the drive magnet
15 may be disposed at three corners, two corners or only one corner
of the four corners of the lens drive device 1.
[0075] While the description above refers to particular embodiments
of the present invention, it will be understood that many
modifications may be made without departing from the spirit
thereof. The accompanying claims are intended to cover such
modifications as would fall within the true scope and spirit of the
present invention.
[0076] The presently disclosed embodiments are therefore to be
considered in all respects as illustrative and not restrictive, the
scope of the invention being indicated by the appended claims,
rather than the foregoing description, and all changes which come
within the meaning and range of equivalency of the claims are
therefore intended to be embraced therein.
* * * * *