U.S. patent application number 12/814973 was filed with the patent office on 2011-01-13 for imaging apparatus.
This patent application is currently assigned to SONY CORPORATION. Invention is credited to Yoshiteru KAMATANI, Kazuhiro SUZUKI.
Application Number | 20110008034 12/814973 |
Document ID | / |
Family ID | 43427542 |
Filed Date | 2011-01-13 |
United States Patent
Application |
20110008034 |
Kind Code |
A1 |
KAMATANI; Yoshiteru ; et
al. |
January 13, 2011 |
IMAGING APPARATUS
Abstract
An imaging apparatus includes: a first member that holds a lens;
a second member to which the first member is fixed; and drive means
for driving the second member in the vertical direction relative to
an imaging plane of an imaging device, wherein the first member has
diameters different from each other and a portion having a small
diameter has a portion that engages the second member, and the
drive means is disposed in a space created by the difference
between the different diameters.
Inventors: |
KAMATANI; Yoshiteru;
(Kanagawa, JP) ; SUZUKI; Kazuhiro; (Kanagawa,
JP) |
Correspondence
Address: |
ROBERT J. DEPKE;LEWIS T. STEADMAN
ROCKEY, DEPKE & LYONS, LLC, SUITE 5450 SEARS TOWER
CHICAGO
IL
60606-6306
US
|
Assignee: |
SONY CORPORATION
Tokyo
JP
|
Family ID: |
43427542 |
Appl. No.: |
12/814973 |
Filed: |
June 14, 2010 |
Current U.S.
Class: |
396/133 |
Current CPC
Class: |
G02B 7/10 20130101; G02B
7/026 20130101; H04N 5/2254 20130101; G02B 13/001 20130101; G02B
7/021 20130101; G02B 7/09 20130101; H04N 5/2252 20130101; G02B 7/04
20130101; G03B 13/34 20130101 |
Class at
Publication: |
396/133 |
International
Class: |
G03B 13/34 20060101
G03B013/34 |
Foreign Application Data
Date |
Code |
Application Number |
Jul 10, 2009 |
JP |
2009-163284 |
Claims
1. An imaging apparatus comprising: a first member that holds a
lens; a second member to which the first member is fixed; and drive
means for driving the second member in the vertical direction
relative to an imaging plane of an imaging device, wherein the
first member has diameters different from each other and a portion
having a small diameter has a portion that engages the second
member, and the drive means is disposed in a space created by the
difference between the different diameters.
2. The imaging apparatus according to claim 1, wherein the first
member holds a plurality of lenses having diameters different from
one another and is shaped to have diameters corresponding to the
diameters of the lenses.
3. The imaging apparatus according to claim 1, wherein the drive
means is a voice coil motor formed of a coil, a magnet, and a yoke,
the voice coil motor is disposed in the space, and the coil of the
voice coil motor is disposed on the side surface of the second
member.
4. The imaging apparatus according to claim 1, wherein the drive
means includes a piezoelectric device, a shaft connected to the
piezoelectric device, and a hook which is connected to the second
member and through which the shaft passes, and the piezoelectric
device, the shaft, and the hook are disposed in the space.
5. The imaging apparatus according to claim 1, wherein the drive
means includes a wire made of a shape memory alloy, a hook to which
the wire is hooked, and electrodes connected to the wire, and the
wire, the hook, and the electrodes are disposed in the space.
6. An imaging apparatus comprising: a first member that holds a
lens; a second member to which the first member is fixed; and a
drive unit configured to drive the second member in the vertical
direction relative to an imaging plane of an imaging device,
wherein the first member has diameters different from each other
and a portion having a small diameter has a portion that engages
the second member, and the drive unit is disposed in a space
created by the difference between the different diameters.
Description
[0001] The present application claims priority to Japanese Patent
Application JP 2009-163284 filed in the Japanese Patent Office on
Jul. 10, 2009, the entire contents of which is hereby incorporated
by reference.
BACKGROUND OF THE INVENTION
[0002] 1. Field of the Invention
[0003] The present invention relates to an imaging apparatus, and
particularly to an imaging apparatus that allows reduction in size
of a lens driving portion.
[0004] 2. Description of the Related Art
[0005] FIG. 1 shows the configuration of an exemplary imaging
apparatus of related art. An imaging apparatus 10 shown in FIG. 1
includes a housing 11, a lens barrel 12, and an imaging device 13.
The imaging apparatus 10 is manufactured by assembling the lens
barrel 12 and the imaging device 13 into the housing 11.
[0006] Lenses 21, 22, and 23 are assembled into the lens barrel 12
and held therein. A thread 24 is provided on the outer side surface
of the lens barrel 12. The thread 24 engages a thread (not shown)
provided on a lens carrier 31 disposed in the housing 11. The
thread engagement between the lens barrel 12 and the lens carrier
31 allows the distance to the imaging device 13 to be adjusted at
the time of manufacture (the focus of the lenses to be adjusted).
After the focus adjustment, the lens barrel 12 is glued to the lens
carrier 31 so that the lens barrel 12 is fixed to the lens carrier
31.
[0007] Coils 32-1 and 32-2 are provided on the side surface of the
lens carrier 31. The coils 32-1 and 32-2 are shown as separate
members for illustration purposes only, but a single coil 32 is in
practice provided on the side surface of the lens carrier 31. A
magnet 33-1 is provided in the housing 11 and faces the coil 32-1.
Similarly, a magnet 33-2 is provided in the housing 11 and faces
the coil 32-2. Each of the magnets 33-1 and 33-2 is provided with a
yoke, which is omitted in FIG. 1. The coil 32, the magnets 33, and
the yokes form a voice coil motor.
[0008] When a current is conducted through the coil 32, a force is
produced in the upward or downward direction in FIG. 1. The
produced force moves the lens carrier 31 in the upward or downward
direction. When the lens carrier 31 is moved, the lens barrel 12
fixed to the lens carrier 31 is also moved. The distance between
the lenses 21 to 23 held in the lens barrel 12 and the imaging
device 13 therefore changes. The mechanism described above enables
autofocusing (AF) (see JP-A-2007-17791, for example).
SUMMARY OF THE INVENTION
[0009] It is desirable in recent years to reduce the size of an AF
driver as the size of digital cameras has been reduced and mobile
phones having a digital camera capability have become popular. The
size of an AF driver can be reduced by reducing the size of an
optical system, such as lenses, but in return the amount of light
likely decreases, disadvantageously resulting in degradation in
image quality. It is therefore not preferable to reduce the size of
lenses or similar optical components in order to reduce the size of
an AF driver. Nevertheless, further reduction in size of the driver
(an imaging apparatus including the driver) is desired, as
described above.
[0010] It is difficult to achieve further size reduction unless a
change is made to the configuration shown in FIG. 1. The size of
the imaging apparatus can be reduced by reducing the sizes of the
lenses 21 to 23 to reduce the size of the lens barrel 12 with no
change made to the configuration shown in FIG. 1. In this case,
however, it is difficult to avoid the degradation in image quality
described above.
[0011] JP-A-2007-17791 describes an imaging apparatus that has a
sector disposed between a subject and a lens and blocking light
incident to the lens and how to reduce the size of the imaging
apparatus. The imaging apparatus described in JP-A-2007-17791
includes a lens group containing a plurality of lenses having
different diameters, and the sector is disposed between a subject
and the lens group and blocks light incident to the lens group. The
lens group is accommodated in a lens barrel. The outer
circumferential sidewall of the lens barrel has a plurality of
stepped sections having different diameters corresponding to the
diameters of the lenses accommodated in the lens barrel, and a
sidewall recess is formed along one of the stepped sections. Sector
drive means for driving the sector is disposed in the sidewall
recess.
[0012] The imaging apparatus described in JP-A-2007-17791 is
desired to be further reduced in size. The imaging apparatus
described in JP-A-2007-17791 has a disadvantageous structure in
which, for example, the lens barrel has no thread mechanism, which
does not allow focus adjustment between the lens group and the
imaging device at the time of manufacture.
[0013] Lens driving methods have also been proposed without using
the driving method described with reference to FIG. 1. For example,
a driving method using a piezoelectric device and a driving method
using a shape memory alloy have been proposed. It is desirable that
the other driving methods described above can also be used and the
size of a drive-related portion can be reduced.
[0014] Thus, it is desirable to reduce a lens driving portion.
[0015] An imaging apparatus according to an embodiment of the
invention includes a first member that holds a lens, a second
member to which the first member is fixed, and drive means for
driving the second member in the vertical direction relative to an
imaging plane of an imaging device. The first member has diameters
different from each other, and a portion having a small diameter
has a portion that engages the second member. The drive means is
disposed in a space created by the difference between the different
diameters.
[0016] The first member may hold a plurality of lenses having
diameters different from one another and may be shaped to have
diameters corresponding to the diameters of the lenses.
[0017] The drive means may be a voice coil motor formed of a coil,
a magnet, and a yoke. The voice coil motor may be disposed in the
space described above. The coil of the voice coil motor may be
disposed on the side surface of the second member.
[0018] The drive means may include a piezoelectric device, a shaft
connected to the piezoelectric device, and a hook which is
connected to the second member and through which the shaft passes.
The piezoelectric device, the shaft, and the hook may be disposed
in the space described above.
[0019] The drive means may include a wire made of a shape memory
alloy, a hook to which the wire is hooked, and electrodes connected
to the wire. The wire, the hook, and the electrodes may be disposed
in the space described above.
[0020] In an imaging apparatus according to another embodiment of
the invention, a thread is provided on a portion of a member that
holds lenses, specifically, on the portion whose diameter
corresponds to the lens having the smallest diameter, and the
thread allows the portion to engage a member that drives the
lenses. Drive means is provided in the space created by the
different diameters.
[0021] According to the embodiments of the invention, the size of a
lens driving portion can be reduced.
BRIEF DESCRIPTION OF THE DRAWINGS
[0022] FIG. 1 shows the configuration of an exemplary imaging
apparatus of related art;
[0023] FIG. 2 shows the configuration of an imaging apparatus of an
embodiment to which the invention is applied;
[0024] FIG. 3 describes the configuration of the imaging
apparatus;
[0025] FIG. 4 describes the size of the imaging apparatus;
[0026] FIGS. 5A and 5B show the configuration of an exemplary
imaging apparatus of related art for comparison;
[0027] FIGS. 6A and 6B show the configuration of the imaging
apparatus of another embodiment to which the invention is
applied;
[0028] FIGS. 7A and 7B show the configuration of an exemplary
imaging apparatus of related art for comparison; and
[0029] FIGS. 8A and 8B show the configuration of the imaging
apparatus of another embodiment to which the invention is
applied.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0030] Embodiments of the invention will be described below with
reference to the drawings.
[0031] The invention can be applied to an imaging apparatus. The
imaging apparatus described herein is specifically an apparatus
accommodated in, for example, a digital still camera and a mobile
phone having a digital still camera capability. In such an imaging
apparatus, autofocusing (AF) is performed by driving a lens (for
example, moving a lens relative to an imaging device in such a way
that the lens approaches the imaging device or travels away
therefrom).
[0032] An imaging apparatus including a driver for performing
autofocusing has a configuration, for example, shown in FIG. 1.
Referring to FIG. 1 again, the imaging apparatus 10 is formed of
the housing 11, which accommodates the lens carrier 31. The lens
carrier 31 is configured to be movable relative to the housing 11
in the upward and downward directions in FIG. 1 (approaching the
imaging device 13 or traveling away therefrom). The lens barrel 12,
which accommodates the plurality of lenses 21 to 23, is disposed in
the lens carrier 31 and fixed thereto.
[0033] The embodiments described below primarily relate to the lens
barrel and the lens carrier of the imaging apparatus described
above. An imaging apparatus using a lens barrel and a lens carrier
to which any of the embodiments described below is applied can be
smaller than an imaging apparatus of related art. When such a
smaller imaging apparatus is accommodated in an apparatus, such as
a digital still camera and a mobile phone, the size of the
apparatus can be reduced. Further, the space for the portion other
than the imaging apparatus can be increased, whereby other
functions can be enhanced.
[0034] A description will next be made of an imaging apparatus
expected to show the advantageous effects described above. Methods
for performing autofocusing having been proposed include a method
using a voice coil motor (the method described with reference to
FIG. 1), a method using a piezoelectric device, and a method using
a wire made of a shape memory alloy. In the following description,
the embodiments will be described with reference to the methods
described above. That is, the following description includes a
first embodiment in which a voice coil motor is used to perform
autofocusing, a second embodiment in which a piezoelectric device
is used to perform autofocusing, and a third embodiment in which a
wire made of a shape memory alloy is used to perform
autofocusing.
[0035] In the following description, a member that holds a lens is
referred to as a lens barrel, a member to which the lens barrel is
fixed is referred to as a lens carrier, and a portion that drives
the lens carrier is referred to as a driver, as appropriate. The
lens barrel is a cylinder shaped in such a way that an upper
diameter (outer diameter) and a lower diameter (outer diameter) are
designed to match the respective lens diameters and hence different
from each other. A portion (thread) that engages the lens carrier
is provided on one of the upper and lower portions of the lens
barrel, the portion having a smaller diameter. The difference in
diameter creates a space, and drive means is provided in the
created space. The drive means in the first to third embodiment
differ from one another as described above and will be described
below.
First Embodiment
[0036] A first embodiment will be described below. FIG. 2 shows an
exemplary configuration of an imaging apparatus 100 in the first
embodiment and is a cross-sectional view of the imaging apparatus
100. The imaging apparatus 100 shown in FIG. 2 includes a housing
101, a lens barrel 102, and an imaging device 103. FIG. 3 is an
exploded view of respective parts of the imaging apparatus 100
shown in FIG. 2.
[0037] Referring to FIG. 3, lenses 21, 22, and 23 are assembled
into the lens barrel 102 and held therein. A thread 111 is provided
on the outer side surface of the lens barrel 102.
[0038] A lens carrier 121 is provided in the housing 101. A thread
122 is provided on the inner side (inner diameter) of the lens
carrier 121. A coil 123 is provided on the outer (outer shape) side
surface of the lens carrier 121. The coil 123 surrounds the side
surface of the lens carrier 121. Magnets 124-1 and 124-2 are
provided in predetermined positions on the inner side (inner
diameter) of the housing 101 and face the coil 123. The magnets
124-1 and 124-2 are disposed on opposite sides of the coil 123.
[0039] Each of the magnets 124-1 and 124-2 is provided with a yoke,
but shown as a combined magnet and yoke in FIGS. 2 and 3 as magnet
124-1 or magnet 124-2. When it is not necessary to distinguish the
magnets 124-1 and 124-2 from each other, the magnets 124-1 and
124-2 are hereinafter simply referred to as magnets 124.
[0040] The thread 111 on the lens barrel 102 engages the thread 122
provided on the lens carrier 121. The engagement between the lens
barrel 102 and the lens carrier 121 allows the distance to the
imaging device 103 to be adjusted at the time of manufacture (the
focus of the lenses to be adjusted). After the focus adjustment,
the lens barrel 102 is glued to the lens carrier 121 so that the
lens barrel 102 is fixed to the lens carrier 121.
[0041] After the lens barrel 102 is inserted into the housing 101
and fixed to the lens carrier 121, the imaging device 103 is
inserted into the housing 101 and fixed thereto. The imaging
apparatus 100 having the configuration shown in FIG. 2 is
manufactured by sequentially assembling the lens barrel 102 and the
imaging device 103 into the housing 101 as described above.
[0042] In the imaging apparatus 100 having the configuration
described above, when a current is conducted through the coil 123
provided on the lens carrier 121, the interaction between the
current and the magnets 124 produces a force oriented in the upward
or downward direction in FIGS. 2 and 3 depending on the direction
in which the current flows. The produced force moves the lens
carrier 121 in the upward or downward direction. When the lens
carrier 121 is moved, the lens barrel 102 fixed to the lens carrier
121 is also moved. The distance between the lenses 21 to 23 held in
the lens barrel 102 and the imaging device 103 therefore changes.
Autofocusing (AF) is performed by the mechanism described
above.
[0043] The structure of the lens barrel 102 will further be
described. Referring to FIG. 3, the lens barrel 102 has a stepped
shape, a shape having two stepped sections in the configuration
shown in FIG. 3. A stepped section 151 contains the lens 23, and a
stepped section 152 contains the lenses 21 and 22. As shown in FIG.
3, the sizes of the lenses 21 to 23 satisfy the following
relationship. [0044] lens 21<lens 22<lens 23
[0045] The diameter of the stepped section 151 containing the lens
23 is therefore larger than that of the stepped section 152
containing the lenses 21 and 22. The diameter of the stepped
section 151 is slightly larger than that of the lens 23. The
diameter of the stepped section 152 is slightly larger than that of
the lens 22 but smaller than that of the lens 23.
[0046] The thread 111 is provided on the stepped section 152. The
thread 111 provided on the stepped section 152 engages the thread
122 provided on the lens carrier 121. The diameter of the lens
carrier 121 is sized in such a way that the thread ill engages the
thread 122. The diameter of the lens carrier 121 is therefore sized
to be slightly larger than that of the stepped section 152.
[0047] Further, the height of the stepped section 152 is shorter
than that of the lens carrier 121. The height used herein means the
length in the up-down direction in FIG. 3 (the direction toward or
away from the imaging device). The height of the lens carrier 121
is determined in such a way that the stepped section 151 of the
lens barrel 102 does not come into contact with an end of the lens
carrier 121 when the lens barrel 102 is fixed to the lens carrier
121.
[0048] The imaging apparatus 10 of related art is now compared with
the imaging apparatus 100 in the first embodiment. The upper
portion of FIG. 4 shows the configuration of the imaging apparatus
10 of related art shown in FIG. 1, and the lower portion of FIG. 4
shows the configuration of the imaging apparatus 100 in the first
embodiment of the invention shown in FIG. 2.
[0049] Each of the imaging apparatus 10 and the imaging apparatus
100 includes the lenses 21 to 23. The imaging apparatus 10 and the
imaging apparatus 100 therefore do not differ from each other in
terms of optical system and can hence capture images having the
same image quality. Further, the imaging device 13 in the imaging
apparatus 10 and the imaging device 103 in the imaging apparatus
100 have the same number of pixels and can capture images having
the same image quality in this regard as well.
[0050] It is, however, obvious that the imaging apparatus 100 is
smaller than the imaging apparatus 10. The reason for this is that
the lens barrel 102 in the imaging apparatus 100 has a stepped
shape and the diameter of the stepped section 152 accommodating the
smaller lenses is smaller than the diameter of the stepped section
151 accommodating the larger lens. The size of the imaging
apparatus 100 can be reduced accordingly. The size of the imaging
apparatus 100 is reduced because the space created by the
difference between the stepped sections 151 and 152, specifically,
the difference in diameter between the stepped sections 151 and
152, accommodates the lens carrier 121, the thread 122, the coil
123, and the magnets 124.
[0051] That is, the size of the imaging apparatus 100 can be
reduced by shaping the lens barrel 102 in such a way that the
diameter thereof gradually decreases in correspondence with the
sizes of the lenses to be accommodated, providing the thread 111 on
the stepped section having the smaller diameter so that the
threaded portion engages the lens carrier 121, and assembling a
driver including the coil 123 and the magnets 124 on the side where
the diameter is smaller.
[0052] In the above description of "shaping the lens barrel 102 in
such a way that the diameter thereof gradually decreases in
correspondence with the sizes of the lenses to be accommodated,"
"the diameter thereof gradually decreases" means that the following
shapes can be employed. That is, for example, a stepped shape, like
the stepped sections 151 and 152 shown in FIG. 3, can be employed.
Although not shown, when three lenses, such as the lenses 21 to 23
shown in FIG. 3, are incorporated, a stepped shape not formed of
two stepped sections but formed of three stepped sections
corresponding to the number of lenses can be employed.
[0053] Alternatively, although not shown, instead of a stepped
shape, for example, a cone shape (part of a cone shape) whose
diameter gradually and continuously decreases in the direction away
from the imaging device 103 can be employed. Still alternatively,
for example, a combined shape in which the threaded portion
(corresponding to the stepped section 152 in FIG. 3) has a
cylindrical shape and the non-threaded portion (corresponding to
the stepped section 151 in FIG. 3) has part of a cone shape can be
employed. Still alternatively, any shape one can think of from the
shapes described above can be employed.
[0054] In the imaging apparatus 10 of related art shown in the
upper portion of FIG. 4, the lens carrier 31 is positioned outside
the lens barrel 12, and the coil 32 and the magnets 33 are further
positioned outside the lens carrier 31. That is, when the
configuration described above is employed, the diameter of the lens
carrier 31 is greater than that of the lens barrel 12, and the coil
32 and the magnets 33 are further positioned outside the
large-diameter lens carrier 31, disadvantageously resulting in an
increased size of the imaging apparatus 10 itself.
[0055] On the other hand, since the imaging apparatus 100 shown in
the lower portion of FIG. 4, to which the first embodiment of the
invention is applied, has the configuration described above, the
lens carrier 121 is positioned outside the lens barrel 102 but
inside the largest-diameter portion (outer diameter) of the lens
barrel 102. Further, the coil 123 and the magnets 124 positioned
outside the lens carrier 121 are positioned inside the outer
diameter of the lens barrel 102. Since none or only part of the
lens carrier 121, the coil 123, and the magnets 124 is thus
positioned outside the outer diameter of the lens barrel 102, the
size of the imaging apparatus 100 itself is reduced.
[0056] In other words, the diameter of the lens barrel 102 on the
side where the imaging device 103 is present is large, whereas the
diameter of the lens barrel 102 on the opposite side is small.
Since the diameters of the two portions of the lens barrel 102
differ from each other, a space is created where the difference is
present. Accommodating drive means (the coil 123, the magnets 124,
and the yokes in this case) for vertically moving the lens carrier
121 relative to the imaging plane of the imaging device 103 in the
space allows the size of the imaging apparatus 100 to be
reduced.
[0057] As described above, the size of the imaging apparatus can be
reduced by applying the invention. Further, the size reduction will
not degrade the quality of a captured image.
[0058] The focus adjustment carried out at the time of manufacture
by using the engagement between the lens barrel 102 and the lens
carrier 121 can be carried out in the same manner as the imaging
apparatus 10 of related art.
Second Embodiment
[0059] A second embodiment will be described below. The second
embodiment relates to a case where a piezoelectric device is used
to perform autofocusing. A piezoelectric device is a passive device
using a piezoelectric effect in which a force applied to a
piezoelectric member is converted into a voltage and vice versa. To
describe an imaging apparatus using a piezoelectric device to
perform autofocusing, the configuration of an imaging apparatus of
related art is first shown in FIGS. 5A and 5B for comparison. FIG.
5A is a top view of an imaging apparatus 200, and FIG. 5B is a side
view (cross-sectional view) of the imaging apparatus 200.
[0060] The imaging apparatus 200 includes a housing 201, a lens
barrel 202, and an imaging device 203. Lenses 21, 22, and 23 are
assembled into the lens barrel 202 and held therein. A thread 211
is provided on the outer side surface of the lens barrel 202.
[0061] A lens carrier 221 is provided in the housing 201. A thread
222 is provided on the inner side (inner diameter) of the lens
carrier 221. A slide hook 223 is provided in a predetermined
position on the outer (outer shape) side surface of the lens
carrier 221. One of the ends of the slide hook 223 is connected to
the lens carrier 221, and the other end has a circular shape having
a circular hole at the center thereof. A shaft 224 passes through
the hole.
[0062] A piezoelectric device 225 fixed to the housing 201 is
attached to the shaft 224. When a current is conducted through the
piezoelectric device 225, a force is produced and then the slide
hook 223 slides. When the slide hook 223 slides, the lens carrier
221 moves relative to the housing 201 in the upward or downward
direction (the direction toward or away from the imaging device
203). Autofocusing is thus performed.
[0063] In the imaging apparatus 200 of related art shown in FIGS.
5A and 5B, the lens carrier 221 is positioned outside the lens
barrel 202 and the slide hook 223, the shaft 224, and the
piezoelectric device 225 are further positioned outside the lens
carrier 221. That is, when the configuration described above is
employed, the diameter of the lens carrier 221 is greater than that
of the lens barrel 202, and the slide hook 223, the shaft 224, and
the piezoelectric device 225 are further positioned outside the
large-diameter lens carrier 221, resulting in an increased size of
the imaging apparatus 200 itself.
[0064] To address the problem, the imaging apparatus in the second
embodiment to which the invention is applied has the configuration
shown in FIGS. 6A and 6B to reduce the size of the imaging
apparatus. FIG. 6A is a top view of an imaging apparatus 250, and
FIG. 6B is a side view (cross-sectional view) of the imaging
apparatus 250.
[0065] The imaging apparatus 250 shown in FIGS. 6A and 6B has a
configuration that is basically the same as that of the imaging
apparatus 200 of related art shown in FIGS. 5A and 5B. The imaging
apparatus 250 includes a housing 251, a lens barrel 252, and an
imaging device 253. Lenses 21, 22, and 23 are assembled into the
lens barrel 252 and held therein. A thread 261 is provided on the
outer side surface of the lens barrel 252.
[0066] A lens carrier 271 is provided in the housing 251. A thread
272 is provided on the inner side (inner diameter) of the lens
carrier 271. A slide hook 273 is provided in a predetermined
position on the outer (outer shape) side surface of the lens
carrier 271. One of the ends of the slide hook 273 is connected to
(integrated with) the lens carrier 271, and the other end has a
circular shape having a circular hole at the center thereof. A
shaft 274 passes through the hole.
[0067] A piezoelectric device 275 fixed to the housing 251 is
attached to the shaft 274. When a current is conducted through the
piezoelectric device 275, a force is produced and then the slide
hook 273 slides. When the slide hook 273 slides, the lens carrier
271 moves relative to the housing 251 in the upward or downward
direction (the direction toward or away from the imaging device
253). Autofocusing is thus performed.
[0068] The structure of the lens barrel 252 will further be
described. Referring to FIG. 6B, the lens barrel 252 has a stepped
shape, a shape having two stepped sections in the configuration
shown in FIG. 6B. A stepped section 281 contains the lens 23, and a
stepped section 282 contains the lenses 21 and 22. As shown in FIG.
6B, the sizes of the lenses 21 to 23 satisfy the following
relationship. [0069] lens 21<lens 22<lens 23
[0070] The diameter of the stepped section 281 containing the lens
23 is therefore larger than that of the stepped section 282
containing the lenses 21 and 22. The diameter of the stepped
section 281 is slightly larger than that of the lens 23. The
diameter of the stepped section 282 is slightly larger than that of
the lens 22 but smaller than that of the lens 23.
[0071] The thread 261 is provided on the stepped section 282. The
thread 261 provided on the stepped section 282 engages the thread
272 provided on the lens carrier 271. The diameter of the lens
carrier 271 is sized in such a way that the thread 261 engages the
thread 272. The diameter of the lens carrier 271 is therefore sized
to be slightly larger than that of the stepped section 282.
[0072] Further, the height of the stepped section 282 is shorter
than the height of the lens carrier 271. The height used herein
means the length in the up-down direction in FIG. 6B (the direction
toward or away from the imaging device 253). The height of the lens
carrier 271 is determined in such a way that the stepped section
281 of the lens barrel 252 does not come into contact with an end
of the lens carrier 271 when the lens barrel 252 is fixed to the
lens carrier 271.
[0073] The imaging apparatus 200 of related art is now compared
with the imaging apparatus 250 in the second embodiment. Each of
the imaging apparatus 200 and the imaging apparatus 250 includes
the lenses 21 to 23. The imaging apparatus 200 and the imaging
apparatus 250 therefore do not differ from each other in terms of
optical system and can hence capture images having the same image
quality. Further, the imaging device 203 in the imaging apparatus
200 and the imaging device 253 in the imaging apparatus 250 have
the same number of pixels and can capture images having the same
image quality in this regard as well.
[0074] It is, however, obvious that the imaging apparatus 250 is
smaller than the imaging apparatus 200. The reason for this is that
the lens barrel 252 in the imaging apparatus 250 has a stepped
shape and the diameter of the stepped section 282 accommodating the
smaller lenses is smaller the diameter of the stepped section 281
accommodating the larger lens. The size of the imaging apparatus
250 can be reduced accordingly. The size of the imaging apparatus
250 is reduced because the space created by the difference between
the stepped sections 281 and 282, specifically, the difference in
diameter between the stepped sections 281 and 282, accommodates all
or part of the lens carrier 271, the slide hook 273, and the shaft
274.
[0075] That is, the size of the imaging apparatus 250 can be
reduced by shaping the lens barrel 252 in such a way that the
diameter thereof gradually decreases in correspondence with the
sizes of the lenses to be accommodated, providing the thread 261 on
the stepped section having the smaller diameter so that the
threaded portion engages the lens carrier 271, and assembling a
driver including the slide hook 273, the shaft 274, and the
piezoelectric device 275 on the side where the diameter is
smaller.
[0076] In the above description of "shaping the lens barrel 252 in
such a way that the diameter thereof gradually decreases in
correspondence with the sizes of the lenses to be accommodated,"
"the diameter thereof gradually decreases" means that the following
shapes can be employed. That is, for example, a stepped shape, like
the stepped sections 281 and 282 shown in FIG. 6B, can be employed.
Although not shown, when three lenses, such as the lenses 21 to 23
shown in FIG. 6B, are incorporated, a stepped shape not formed of
two stepped sections but formed of three stepped sections
corresponding to the number of lenses can be employed.
[0077] Alternatively, although not shown, instead of a stepped
shape, for example, a cone shape (part of a cone shape) whose
diameter gradually and continuously decreases in the direction away
from the imaging device 253 can be employed. Still alternatively,
for example, a combined shape in which the threaded portion
(corresponding to the stepped section 282 in FIG. 6B) has a
cylindrical shape and the non-threaded portion (corresponding to
the stepped section 281 in FIG. 6B) has part of a cone shape can be
employed. Still alternatively, any shape one can think of from the
shapes described above can be employed.
[0078] The imaging apparatus 200 of related art shown in FIGS. 5A
and 5B disadvantageously has a structure that causes an increase in
size of the imaging apparatus 200 itself, as described above.
However, since the imaging apparatus 250 shown in FIGS. 6A and 6B,
to which the second embodiment of the invention is applied, has the
configuration described above, the lens carrier 271 is positioned
outside the lens barrel 252 but inside the largest-diameter portion
of the lens barrel 252.
[0079] Further, all or part of the driver including the slide hook
273, the shaft 274, and the piezoelectric device 275 positioned
outside the lens carrier 271 is positioned inside the
largest-diameter portion (largest outer diameter) of the lens
barrel 252. Since none or only part of the lens carrier 271, the
slide hook 273, the shaft 274, and the piezoelectric device 275 is
thus positioned outside the largest outer diameter of the lens
barrel 252, the size of the imaging apparatus 250 itself is
reduced.
[0080] In other words, the diameter of the lens barrel 252 on the
side where the imaging device 253 is present is large, whereas the
diameter of the lens barrel 252 on the opposite side is small.
Since the diameters of the two portions of the lens barrel 252
differ from each other, a space is created where the difference is
present. Accommodating drive means (the slide hook 273, the shaft
274, and the piezoelectric device 275 in this case) for vertically
moving the lens carrier 271 relative to the imaging plane of the
imaging device 253 in the space allows the size of the imaging
apparatus 250 to be reduced.
[0081] As described above, the size of the imaging apparatus can be
reduced by applying the invention.
[0082] The focus adjustment carried out at the time of manufacture
by using the engagement between the lens barrel 252 and the lens
carrier 271 can be carried out in the same manner as the imaging
apparatus 200 of related art.
[0083] The imaging apparatus 250 shown in FIGS. 6A and 6B includes
one set of the slide hook 273 and the shaft 274, two to four sets
of a slide hook and a shaft can be provided. The sets of a slide
hook and a shaft other than the set of the slide hook 273 and the
shaft 274 are provided to support the lens carrier 271 but provided
with no piezoelectric device. Providing a plurality of sets of a
slide hook and a shaft in the imaging apparatus 250 does not
increase the size of the configuration of the imaging apparatus
250, but the imaging apparatus 250 can still be reduced in
size.
Third Embodiment
[0084] A third embodiment will be described below. The third
embodiment relates to a case where a wire made of a shape memory
alloy is used to perform autofocusing. A shape memory alloy is
characterized in that the length thereof increases or decreases
when a current is conducted therethrough. To describe an imaging
apparatus using a wire made of a shape memory alloy to perform
autofocusing, the configuration of an imaging apparatus of related
art is first shown in FIGS. 7A and 7B for comparison. FIG. 7A is a
top view of an imaging apparatus 300, and FIG. 7B is a side view
(cross-sectional view) of the imaging apparatus 300.
[0085] The imaging apparatus 300 includes a housing 301, a lens
barrel 302, and an imaging device 303. Lenses 21, 22, and 23 are
assembled into the lens barrel 302 and held therein. A thread 311
is provided on the outer side surface of the lens barrel 302.
[0086] A lens carrier 321 is provided in the housing 301. A thread
322 is provided on the inner side (inner diameter) of the lens
carrier 321. Hooks 323-1 and 323-2 are provided in predetermined
positions on the outer (outer shape) side surface of the lens
carrier 321. The hooks 323-1 and 323-2 are disposed on opposite
sides of the lens carrier 321. A wire 332 made of a shape memory
alloy is hooked to the hooks 323-1 and 323-2 (hereinafter simply
referred to as the hooks 323 when they are not necessary to be
distinguished and the same applies to other portions in the
following description).
[0087] The wire 332 is also connected to electrodes 331-1 and
331-2. When a current is conducted from the electrodes 331-1 and
331-2 through the wire 332 and the temperature thereof increases,
the wire 332 made of a shape memory alloy decreases in length. When
the length of the wire 332 decreases, the hooks 323 to which the
wire 332 is hooked are lifted relative to the housing 301.
[0088] Since the hooks 323 are integrated with the lens carrier
321, the hooks 323 lifted relative to the housing 301 lift the lens
carrier 321 relative to the housing 301. In this way, the lens
carrier 321 is driven. Conversely, when the current flowing through
the wire 332 is terminated, the temperature thereof decreases and
the length thereof increases. When the length of the wire 332
increases (returns back to its original length), the hooks 323 and
hence the lens carrier 321 are lowered.
[0089] The lens barrel 302, which holds the lenses, fits into the
lens carrier 321. Driving the lens carrier 321 in the way described
above therefore changes the position of the lenses held in the lens
barrel 302 and hence the focal distance is adjusted. That is,
autofocusing is performed.
[0090] In the imaging apparatus 300 of related art shown in FIGS.
7A and 7B, the lens carrier 321 is positioned outside the lens
barrel 302, and the hooks 323, the wire 332, and the electrodes 331
are further positioned outside the lens carrier 321. That is, when
the configuration described above is employed, the diameter of the
lens carrier 321 is greater than that of the lens barrel 302, and
the hooks 323, the wire 332, and the electrodes 331 are further
positioned outside the large-diameter lens carrier 321, resulting
in an increased size of the imaging apparatus 300 itself.
[0091] To address the problem, the imaging apparatus in the third
embodiment to which the invention is applied has the configuration
shown in FIGS. 8A and 8B to achieve size reduction. FIG. 8A is a
top view of an imaging apparatus 350, and FIG. 8B is a side view
(cross-sectional view) of the imaging apparatus 350.
[0092] The imaging apparatus 350 shown in FIGS. 8A and 8B has a
configuration that is basically the same as that of the imaging
apparatus 300 of related art shown in FIGS. 7A and 7B. The imaging
apparatus 350 includes a housing 351, a lens barrel 352, and an
imaging device 353. Lenses 21, 22, and 23 are assembled into the
lens barrel 352 and held therein. A thread 361 is provided on the
outer side surface of the lens barrel 352.
[0093] A lens carrier 371 is provided in the housing 351. A thread
372 is provided on the inner side (inner diameter) of the lens
carrier 371. Hooks 373-1 and 373-2 are provided in predetermined
positions on the outer (outer shape) side surface of the lens
carrier 371. The hooks 373-1 and 373-2 are disposed on opposite
sides of the lens carrier 371. A wire 382 made of a shape memory
alloy is hooked to the hooks 373-1 and 373-2.
[0094] The wire 382 is also connected to electrodes 381-1 and
381-2. When a current is conducted from the electrodes 381-1 and
381-2 through the wire 382 and the temperature thereof increases,
the wire 382 made of a shape memory alloy decreases in length. When
the length of the wire 382 decreases, the hooks 373 to which the
wire 382 is hooked are lifted relative to the housing 351.
[0095] Since the hooks 373 are integrated with the lens carrier
371, the hooks 373 lifted relative to the housing 351 lift the lens
carrier 371 relative to the housing 351. In this way, the lens
carrier 371 is driven. Conversely, when the current flowing through
the wire 382 is terminated, the temperature thereof decreases and
the length thereof increases. When the length of the wire 382
increases (returns back to its original length), the hooks 373 and
hence the lens carrier 371 are lowered.
[0096] The lens barrel 352, which holds the lenses, fits into the
lens carrier 371. Driving the lens carrier 371 in the way described
above therefore changes the position of the lenses held in the lens
barrel 352 and hence the focal distance is adjusted. That is,
autofocusing is performed.
[0097] The structure of the lens barrel 352 will further be
described. Referring to FIG. 8B, the lens barrel 352 has a stepped
shape, a shape having two stepped sections in the configuration
shown in FIG. 8B. A stepped section 391 contains the lens 23, and a
stepped section 392 contains the lenses 21 and 22. As shown in FIG.
8B, the sizes of the lenses 21 to 23 satisfy the following
relationship. [0098] lens 21<lens 22<lens 23
[0099] The diameter of the stepped section 391 containing the lens
23 is therefore larger than that of the stepped section 392
containing the lenses 21 and 22. The diameter of the stepped
section 391 is slightly larger than that of the lens 23. The
diameter of the stepped section 392 is slightly larger than that of
the lens 22 but smaller than that of the lens 23.
[0100] The thread 361 is provided on the stepped section 392. The
thread 361 provided on the stepped section 392 engages the thread
372 provided on the lens carrier 371. The diameter of the lens
carrier 371 is sized in such a way that the thread 361 engages the
thread 372. The diameter of the lens carrier 371 is therefore sized
to be slightly larger than that of the stepped section 392.
[0101] Further, the height of the stepped section 392 is shorter
than the height of the lens carrier 371. The height used herein
means the length in the up-down direction in FIG. 8B (the direction
toward or away from the imaging device 353). The height of the lens
carrier 371 is determined in such a way that the stepped section
391 of the lens barrel 352 does not come into contact with an end
of the lens carrier 371 when the lens barrel 352 is fixed to the
lens carrier 371.
[0102] The length of the hooks 373 attached to the lens carrier 371
is sized in such a way that part of the tips of the hooks 373
extends off the largest diameter (largest outer diameter) of the
lens barrel 352 or the tips are preferably within the diameter of
the lens barrel 352.
[0103] The imaging apparatus 300 (FIGS. 7A and 7B) of related art
is now compared with the imaging apparatus 350 (FIGS. 8A and 8B) in
the third embodiment. Each of the imaging apparatus 300 and the
imaging apparatus 350 includes the lenses 21 to 23. The imaging
apparatus 300 and the imaging apparatus 350 therefore do not differ
from each other in terms of optical system and can hence capture
images having the same image quality. Further, the imaging device
303 in the imaging apparatus 300 and the imaging device 353 in the
imaging apparatus 350 have the same size or the same number of
pixels and can capture images having the same image quality in this
regard as well.
[0104] It is, however, obvious that the imaging apparatus 350 is
smaller than the imaging apparatus 300. The reason for this is that
the lens barrel 352 in the imaging apparatus 350 has a stepped
shape and the diameter of the stepped section 392 accommodating the
smaller lenses is smaller than the diameter of the stepped section
391 accommodating the larger lens. The size of the imaging
apparatus 350 can be reduced accordingly. The size of the imaging
apparatus 350 is reduced because the space created by the
difference between the stepped sections 391 and 392, specifically,
the difference in diameter between the stepped sections 391 and
392, accommodates all or part of the lens carrier 371, the hooks
373, and the electrodes 381.
[0105] That is, the size of the imaging apparatus 350 can be
reduced by shaping the lens barrel 352 in such a way that the
diameter thereof gradually decreases in correspondence with the
sizes of the lenses to be accommodated, providing the thread 361 on
the stepped section having the smaller diameter so that the
threaded portion engages the lens carrier 371, and assembling a
driver including the hooks 373, the electrodes 381, and the wire
382 on the side where the diameter is smaller.
[0106] In the above description of "shaping the lens barrel 352 in
such a way that the diameter thereof gradually decreases in
correspondence with the sizes of the lenses to be accommodated,"
"the diameter thereof gradually decreases" means that the following
shapes can be employed. That is, for example, a stepped shape, like
the stepped sections 391 and 392 shown in FIG. 8B, can be employed.
Although not shown, when three lenses, such as the lenses 21 to 23
shown in FIG. 8B, are incorporated, a stepped shape not formed of
two stepped sections but formed of three stepped sections
corresponding to the number of lenses can be employed.
[0107] Alternatively, although not shown, instead of a stepped
shape, for example, a cone shape (part of a cone shape) whose
diameter gradually and continuously decreases in the direction away
from the imaging device 353 can be employed. Still alternatively,
for example, a combined shape in which the threaded portion
(corresponding to the stepped section 392 in FIG. 8B) has a
cylindrical shape and the non-threaded portion (corresponding to
the stepped section 391 in FIG. 8B) has part of a cone shape can be
employed. Still alternatively, any shape one can think of from the
shapes described above can be employed.
[0108] The imaging apparatus 300 of related art shown in FIGS. 7A
and 7B disadvantageously has a structure that causes an increase in
size of the imaging apparatus 300 itself, as described above.
However, since the imaging apparatus 350 shown in FIGS. 8A and 8B,
to which the third embodiment of the invention is applied, has the
configuration described above, the lens carrier 371 is positioned
outside the lens barrel 352 but inside the largest-diameter (outer
diameter) portion of the lens barrel 352.
[0109] Further, all or part of the driver including the hooks 373,
the electrodes 381, and the wire 382 positioned outside the lens
carrier 371 is positioned inside the largest-diameter portion of
the lens barrel 352. Since none or only part of the lens carrier
371, the hooks 373, the electrodes 381, and the wire 382 is thus
positioned outside the largest diameter of the lens barrel 352, the
size of the imaging apparatus 350 itself is reduced.
[0110] In other words, the diameter of the lens barrel 352 on the
side where the imaging device 353 is present is large, whereas the
diameter of the lens barrel 352 on the opposite side is small.
Since the diameters of the two portions of the lens barrel 352
differ from each other, a space is created where the difference is
present. Accommodating drive means (the hooks 373, the electrodes
381, and the wire 382 in this case) for vertically moving the lens
carrier 371 relative to the imaging plane of the imaging device 353
in the space allows the size of the imaging apparatus 350 to be
reduced.
[0111] As described above, the size of the imaging apparatus can be
reduced by applying the invention. Further, the size reduction will
not degrade the quality of a captured image.
[0112] The focus adjustment carried out at the time of manufacture
by using the engagement between the lens barrel 352 and the lens
carrier 371 can be carried out in the same manner as the imaging
apparatus 300 of related art.
[0113] The imaging apparatus 350 shown in FIGS. 8A and 8B includes
the two hooks 373, the two electrodes 381, and the wire 382
connected to the hooks 373 and the electrodes 381 and surrounding
the lens carrier 371. The imaging apparatus 350 may alternatively
include one of the hooks 373, the two electrodes 381, and the wire
382 connected to the hook 373 and the electrodes 381 and
surrounding the lens carrier 371. That is, the imaging apparatus
350 can, for example, be configured in such a way that the ends of
the wire 382 are connected to the electrodes 381-1 and 381-2 and
the hook 373-1 (or hook 373-2) is positioned in a central portion
of the wire 382.
[0114] The configuration described above does not increase the size
of the configuration of the imaging apparatus 350, but the imaging
apparatus 350 can still be reduced in size.
[0115] The above first to third embodiments have been described
with reference to a case where the lens closer to the imaging
device is larger and the size of the lenses decreases in the
direction away from the imaging device. The invention is, however,
not limited to the lens layout described above. That is, for
example, the invention can be applied to a case where the lens
farther away from the imaging device is larger and the size of the
lenses decreases in the direction toward the imaging device.
[0116] When the lens layout described above is employed, the
threads and the driver are provided on the side where the stepped
portion accommodating smaller lenses is present. The size of the
imaging apparatus can, of course, be reduced even when the lens
layout described above is employed, as in the above
embodiments.
[0117] The above embodiments have been described with reference to
the imaging apparatus including the three lenses 21 to 23, but the
invention is not necessarily applied to an imaging apparatus
including three lenses. That is, the invention can be applied to an
imaging apparatus including a plurality of lenses.
[0118] When a plurality of lenses are provided and the diameter of
the lenses increases (or decreases) toward the imaging device, the
lens barrel holding the plurality of lenses is configured not to
simply have a cylindrical shape but have a stepped shape according
to the diameters of the lenses or a shape at least part of which
gradually decreases in diameter. Shaping the lens carrier that
holds the lens barrel in accordance with the shape of the lens
barrel provides a sufficient space between the lens carrier and the
inner wall of the lens module on the side where a subject is
present, whereby the actuator can be disposed in the space. The
lens module can therefore be reduced in size.
[0119] In an imaging apparatus of related art having a structure in
which no thread is provided on the lens barrel and the lens
carrier, the focus adjustment with respect to the imaging device
may not be carried out. In the present invention, threads are
provided on the lens barrel and the lens carrier. Providing threads
on the lens barrel and the lens carrier allows the focus adjustment
with respect to the imaging device to be carried out, for example,
at the time of manufacture.
[0120] The stroke typically required to perform autofocusing can be
minimized and the requirements on actuator characteristics can be
lowered by applying the invention. Further, the resultant smaller
stroke or movable range advantageously reduces power
consumption.
[0121] Embodiments of the invention are not limited to those
described above, but a variety of changes can be made to the extent
that they do not depart from the spirit of the invention.
[0122] The present application contains subject matter related to
that disclosed in Japanese Priority Patent Application JP
2009-163284 filed in the Japan Patent Office on Jul. 10, 2009, the
entire contents of which is hereby incorporated by reference.
* * * * *