U.S. patent application number 09/917878 was filed with the patent office on 2002-02-21 for moving mechanism.
This patent application is currently assigned to Fuji Photo Optical Co., Ltd.. Invention is credited to Nishimura, Syunji, Noguchi, Yokio, Nozawa, Masaya, Nozawa, Mieko.
Application Number | 20020021894 09/917878 |
Document ID | / |
Family ID | 18725962 |
Filed Date | 2002-02-21 |
United States Patent
Application |
20020021894 |
Kind Code |
A1 |
Nishimura, Syunji ; et
al. |
February 21, 2002 |
Moving mechanism
Abstract
A moving mechanism for a cylinder is provided, in which a
projection and groove are engaged by relative movement different
from that of a helicoid mechanism and movement of inner and outer
cylinders relative to each other can be freely set. In the moving
mechanism, a first helicoid thread is helically formed on the inner
surface of an intermediate cylinder, a second helicoid thread that
threadably engages with the first helicoid thread is helically
formed on the outer surface of a movable cylinder, and the
intermediate cylinder is rotated so the movable cylinder is moved
relative to the intermediate cylinder. A projection is formed on
the outer surface of the movable cylinder and a groove engageable
with the projection is formed in the inner surface of the
intermediate cylinder. In a range where the first and second
helicoid threads threadably engage with each other upon relative
movement of the movable cylinder, the groove is formed parallel to
the first helicoid thread. In a range where the first and second
helicoid threads do not threadably engage with each other, the
groove has a nonparallel region not parallel to at least the first
helicoid thread.
Inventors: |
Nishimura, Syunji;
(Saitama-shi, JP) ; Nozawa, Masaya; (Saitama-shi,
JP) ; Noguchi, Yokio; (Saitama-shi, JP) ;
Nozawa, Mieko; (Osato-gun, JP) |
Correspondence
Address: |
LEYDIG VOIT & MAYER, LTD
700 THIRTEENTH ST. NW
SUITE 300
WASHINGTON
DC
20005-3960
US
|
Assignee: |
Fuji Photo Optical Co.,
Ltd.
324, Uetake-cho 1-chome
Saitama-shi
JP
3308624
|
Family ID: |
18725962 |
Appl. No.: |
09/917878 |
Filed: |
July 31, 2001 |
Current U.S.
Class: |
396/72 |
Current CPC
Class: |
G03B 17/00 20130101 |
Class at
Publication: |
396/72 |
International
Class: |
G03B 017/00 |
Foreign Application Data
Date |
Code |
Application Number |
Aug 1, 2000 |
JP |
2000-233444 |
Claims
What is claimed is:
1. A moving mechanism in which a first helicoid thread is helically
formed on an inner surface of a first cylinder, a second helicoid
thread that threadably engages with the first helicoid thread of
the first cylinder is helically formed on an outer surface of a
second cylinder, and either one of the first and second cylinders
is rotated with respect to the other cylinder, so the other
cylinder is moved relative to one cylinder, wherein said moving
mechanism includes a projection formed on the outer surface of the
second cylinder, and a groove formed in the inner surface of the
first cylinder and adapted to engage with the projection, the
groove is formed parallel to the first helicoid thread in a range
where the first and second helicoid threads threadably engage with
each other upon movement of the first and second cylinders relative
to each other, and has a nonparallel region not parallel to at
least the first helicoid thread within a range where the first and
second helicoid threads do not threadably engage with each
other.
2. A moving mechanism in which a first helicoid thread is helically
formed on an inner surface of a first cylinder, a second helicoid
thread that threadably engages with the first helicoid thread of
the first cylinder is helically formed on an outer surface of a
second cylinder, and either one of the first and second cylinders
is rotated with respect to the other cylinder, so the other
cylinder is moved relative to one cylinder, wherein said moving
mechanism includes a projection formed on the inner surface of the
first cylinder, and a groove formed in the outer surface of the
second cylinder and adapted to engage with the projection, the
groove is formed parallel to the second helicoid thread in a range
where the first and second helicoid threads threadably engage with
each other upon movement of the first and second cylinders relative
to each other, and has a nonparallel region not parallel to at
least the second helicoid thread within a range where the first and
second helicoid threads do not threadably engage with each
other.
3. A moving mechanism according to claim 1, wherein a photographic
lens is accommodated in the first and second cylinders, and said
moving mechanism is used for a lens barrel for the photographic
lens.
4. A moving mechanism according to claim 2, wherein a photographic
lens is accommodated in the first and second cylinders, and said
moving mechanism is used for a lens barrel for the photographic
lens.
Description
BACKGROUND OF THE INVENTION
[0001] 1. Field of the Invention
[0002] The present invention relates to a moving mechanism for
moving a plurality of inner and outer cylinders provided in a
multiple manner in the axial direction relative to each other and,
more particularly, to a moving mechanism used in, e.g., a lens
barrel for a camera.
[0003] 2. Related Background Art
[0004] Conventionally, as a mechanism for moving a plurality of
cylinders in the axial direction relative to each other, a helicoid
mechanism is known as described in Japanese Patent Laid-Open No.
10-31150, in which either one of a root and crest is helically
formed on the inner surface of an outer cylinder, and the other one
is formed on the outer surface of an inner cylinder. One of the
outer and inner cylinders is rotated with respect to the other,
thereby transforming a rotary motion into a rectilinear motion.
[0005] According to the helicoid mechanism described in this
reference, a large-width portion is formed in part of the root by
widening the width of the root. The amount of movement of the outer
and inner cylinders relative to each other is increased by using
the large-width portion.
[0006] In the above helicoid mechanism, the degree of freedom of
the movement of the outer and inner cylinders relative to each
other is small. More specifically, in the above helicoid mechanism,
it is certain that the amount of movement of the outer and inner
cylinders relative to each other can be increased with respect to
rotation of the outer or inner cylinder by utilizing the
large-width portion formed in part of the root. As shown in FIG. 6
of this reference, since the crest (34b) is formed adjacent to the
root, the amount of increase in the relative movement is limited to
a certain level due to the position of the crest and the like, and
becomes small. Also, it is difficult to conversely decrease the
amount of movement of the outer and inner cylinders relative to
each other with respect to movement obtained by helicoid.
SUMMARY OF THE INVENTION
[0007] The present invention has been made in order to solve the
above drawbacks, and has an object to provide a moving mechanism
for a cylinder in which the movement of inner and outer cylinders
relative to each other can be freely set.
[0008] According to an aspect of the present invention, there is
provided a moving mechanism in which a first helicoid thread is
helically formed on an inner surface of a first cylinder, a second
helicoid thread that threadably engages with the first helicoid
thread of the first cylinder is helically formed on an outer
surface of a second cylinder, and either one of the first and
second cylinders is rotated with respect to the other cylinder, so
the other cylinder is moved relative to one cylinder, wherein the
moving mechanism includes a projection formed on the outer surface
of the second cylinder, and a groove formed in the inner surface of
the first cylinder and adapted to engage with the projection, the
groove is formed parallel to the first helicoid thread in a range
where the first and second helicoid threads threadably engage with
each other upon movement of the first and second cylinders relative
to each other, and has a nonparallel region not parallel to at
least the first helicoid thread within a range where the first and
second helicoid threads do not threadably engage with each
other.
[0009] According to another aspect of the present invention, there
is provided a moving mechanism in which a first helicoid thread is
helically formed on an inner surface of a first cylinder, a second
helicoid thread that threadably engages with the first helicoid
thread of the first cylinder is helically formed on an outer
surface of a second cylinder, and either one of the first and
second cylinders is rotated with respect to the other cylinder, so
the other cylinder is moved relative to one cylinder, wherein the
moving mechanism includes a projection formed on the inner surface
of the first cylinder, and a groove formed in the outer surface of
the second cylinder and adapted to engage with the projection, the
groove is formed parallel to the second helicoid thread in a range
where the first and second helicoid threads threadably engage with
each other upon movement of the first and second cylinders relative
to each other, and has a nonparallel region not parallel to at
least the second helicoid thread within a range where the first and
second helicoid threads do not threadably engage with each
other.
[0010] According to the present invention, a photographic lens is
preferably accommodated in the first and second cylinders, and the
moving mechanism is preferably used for a lens barrel for the
photographic lens.
[0011] According to the present invention, the first and second
cylinders engage with each other not only through the first and
second helicoid threads but also through the projection and groove.
Therefore, within the range where the first and second helicoid
threads threadably engage with each other upon movement of the
first and second cylinders relative to each other, the first and
second cylinders can be precisely moved relative to each other
through a helicoid mechanism comprised of the first and second
helicoid threads. In the range where the first and second helicoid
threads do not threadably engage with each other, the first and
second cylinders can be moved relative to each other through the
projection and groove by relative movement different from that by
the helicoid mechanism. When a nonparallel region is formed in the
groove, movement of the first and second cylinders relative to each
other can be freely set.
[0012] The present invention will become more fully understood from
the detailed description given hereinbelow and the accompanying
drawings which are given by way of illustration only, and thus are
not to be considered as limiting the present invention.
[0013] Further scope of applicability of the present invention will
become apparent from the detailed description given hereinafter.
However, it should be understood that the detailed description and
specific examples, while indicating preferred embodiments of the
invention, are given by way of illustration only, since various
changes and modifications within the spirit and scope of the
invention will become apparent to those skilled in the art from
this detailed description.
BRIEF DESCRIPTION OF THE DRAWINGS
[0014] FIG. 1 is a sectional view of a lens barrel using a moving
mechanism according to an embodiment of the present invention;
[0015] FIG. 2 is a view of a movable cylinder for the lens barrel
of FIG. 1;
[0016] FIG. 3 is a view of the lens barrel of FIG. 1;
[0017] FIG. 4 is a view of a moving mechanism in the lens barrel of
FIG. 1;
[0018] FIG. 5 is a view of a barrier opening/closing unit for the
lens barrel of FIG. 1; and
[0019] FIG. 6 is a view for explaining the operation of the lens
barrel of FIG. 1.
DESCRIPTION OF THE PREFERRED EMBODIMENT
[0020] A preferred embodiment of the present invention will be
described with reference to the accompanying drawings. In the
drawings, the same elements are denoted by the same reference
numerals, and a detailed description thereof will be omitted. Note
that the dimensional proportions in the drawings do not necessary
coincide with described ones.
[0021] A moving mechanism according to this embodiment is applied
to a lens barrel for a photographic lens in a camera.
[0022] FIG. 1 is a sectional view of a lens barrel using the moving
mechanism according to this embodiment. As shown in FIG. 1, the
lens barrel has a movable cylinder 200 and intermediate cylinder
300. The movable cylinder 200 and intermediate cylinder 300 can be
extended from and retracted in a camera body 800. The intermediate
cylinder 300 is the first cylinder with two open ends, and is
accommodated in a stationary cylinder 400 set in the camera body
800. The intermediate cylinder 300 has helicoid threads 301 and
gear teeth 302 on the outer surface of its rear portion. For
example, the helicoid threads 301 are formed as helical recesses
and projections on the outer surface of the rear portion of the
intermediate cylinder 300, and the large number of gear teeth 302
are formed between the projections of the helicoid threads 301
along the outer periphery.
[0023] The helicoid threads 301 threadably engage with helicoid
threads 401 formed in the inner surface of the stationary cylinder
400. The gear teeth 302 mesh with a driving gear (not shown) set in
the camera body 800. Therefore, when the driving gear rotates, the
intermediate cylinder 300 rotates through the gear teeth 302 about
an optical axis O as the center. When the intermediate cylinder 300
rotates, it moves along the optical axis O with respect to the
stationary cylinder 400 because of the threadable engagement of the
helicoid threads 301 and helicoid threads-401.
[0024] The intermediate cylinder 300 accommodates the movable
cylinder 200. The movable cylinder 200 is the second cylinder that
moves along the optical axis O in the same manner as the
intermediate cylinder 300, and is arranged concentrically with the
intermediate cylinder 300 about the optical axis O as the center.
The movable cylinder 200 has second helicoid threads 201 serving as
helical recesses and projections on the outer surface of its rear
portion. The second helicoid threads 201 threadably engage with
first helicoid threads 304 formed on the inner surface of the
intermediate cylinder 300.
[0025] The movable cylinder 200 is locked by a straight moving
cylinder 500. This prevents the movable cylinder 200 from rotating
about the optical axis O, and allows it only to linearly move along
the optical axis O. Therefore, when the intermediate cylinder 300
rotates, the movable cylinder 200 moves relative to the
intermediate cylinder 300 along the optical axis O because of the
threadable engagement of the first and second helicoid threads 304
and 201.
[0026] The straight moving cylinder 500 is a cylinder disposed
inside the movable cylinder 200, and has a key 501 at its rear
portion. The key 501 is locked by a vertical groove 402 formed in
the inner surface of the stationary cylinder 400. This prevents the
straight moving cylinder 500 from rotating about the optical axis
O, and allows it only to move linearly along the optical axis
O.
[0027] The rear end of the straight moving cylinder 500 engages
with the intermediate cylinder 300 while rotation of the
intermediate cylinder 300 is allowed. Thus, upon movement of the
intermediate cylinder 300 in the direction of optical axis, the
straight moving cylinder 500 does not rotate but moves
linearly.
[0028] A front-group lens 600 and rear-group lens 700 are disposed
inside the straight moving cylinder 500. The front-group lens 600
and rear-group lens 700 are lens groups that constitute an optical
lens system.
[0029] The rear-group lens 700 is attached to a rear-group lens
frame 701. The rear-group lens frame 701 engages with the straight
moving cylinder 500 to be slidable in the direction of optical
axis. The rear-group lens frame 701 forms cam followers 702
projecting outward from its side portion. The cam followers 702
extend through the straight moving cylinder 500 and movable
cylinder 200 and are inserted in cam grooves 306 formed in the
inner surface of the intermediate cylinder 300. Hence, when the
intermediate cylinder 300 rotates, the rear-group lens 700 moves
along the optical axis O to follow the cam grooves 306. The cam
grooves 306 will be described later in detail.
[0030] The front-group lens 600 is attached to a front-group lens
frame 601. The front-group lens frame 601 is connected to a shutter
unit 602 and moves together with it. The shutter unit 602 is
attached to the straight moving cylinder 500 to be slidable in the
direction of optical axis.
[0031] A groove 603 extending in the direction of optical axis is
formed in the side surface of the shutter unit 602. A projection
202 projecting from the inner wall of the movable cylinder 200 is
inserted in the groove 603. Hence, the shutter unit 602 and
front-group lens 600 are movable relative to the movable cylinder
200 for a distance corresponding to the length of the groove
603.
[0032] The shutter unit 602 has a click ball 604. The click ball
604 is a solid sphere for moving the front-group lens 600 together
with the intermediate cylinder 300, and is arranged in an
installation hole 605 extending through the rear portion of the
shutter unit 602. The shutter unit 602 has a press member 606. The
press member 606 serves as a biasing means for biasing the click
ball 604 outward.
[0033] Recesses 502 for catching the click ball 604 are formed in
the inner surface of the straight moving cylinder 500. The
plurality of recesses 502 are formed at a constant interval along
the optical axis.
[0034] A movable mask 100 is disposed inside the straight moving
cylinder 500. The movable mask 100 is attached to the straight
moving cylinder 500 to be movable in the direction of optical axis,
and is biased by a spring 101 toward the proximal end. A spring 102
is provided between the movable mask 100 and rear-group lens frame
701, and biases the rear-group lens frame 701 toward the proximal
end.
[0035] FIG. 2 is a perspective view of the movable cylinder.
[0036] As shown in FIG. 2, the plurality of second helicoid threads
201 as helical recesses and projections are formed on the outer
surface of the rear portion of the movable cylinder 200 serving as
the second cylinder. The second helicoid threads 201 form crests
and roots helically. A projection 203 is formed on the crest of one
second helicoid thread 201. The projection 203 projects upward from
the crest of the second helicoid thread 201. Alternatively, the
projection 203 may be formed on the root of one second helicoid
thread 201. In this case, the projection 203 is higher than the
crest of the second helicoid thread 201.
[0037] The helicoid threads of the stationary cylinder will be
described in detail.
[0038] FIG. 3 is a partial developed view of the inner surface of
the stationary cylinder 400. As shown in FIG. 3, the large number
of helicoid threads 401 are formed on an inner surface 403 of the
stationary cylinder 400 to be tilted with respect to the direction
of the optical axis O, that is, to the optical axis. The helicoid
threads 401 form elongated grooves to accommodate helicoid threads
301 of the intermediate cylinder 300, and guide the intermediate
cylinder 300 in the direction of optical axis upon rotation of the
intermediate cylinder 300.
[0039] The helicoid threads 401 are formed between parallel
projecting ridges 404. At the end of each helicoid thread 401, only
the projecting ridge 404 at the distal end side is formed
perpendicularly to the optical axis.
[0040] Therefore, when the intermediate cylinder 300 is retracted
into the stationary cylinder 400, the helicoid threads 301 are
disengaged from the helicoid threads 401, and the intermediate
cylinder 300 can rotate without movement in the direction of
optical axis.
[0041] The cam grooves and helicoid threads of the intermediate
cylinder will be described in detail.
[0042] FIG. 4 is a partial developed view of the inner surface of
the intermediate cylinder 300. As shown in FIG. 4, the large number
of first helicoid threads 304 are formed in an inner surface 307 of
the intermediate cylinder 300 to be tilted with respect to the
direction of the optical axis O, i.e., to the optical axis. The
first helicoid threads 304 form crests and roots helically, and
threadably engage with the second helicoid threads 201 of the
movable cylinder 200 to guide the movable cylinder 200 in the
direction of optical axis.
[0043] Grooves 304a are formed in part of the roots of some first
helicoid threads 304 which form the plurality of parallel crests
and roots, to be deeper than corresponding portions of other roots.
The grooves 304a are longer toward the proximal end than other
first helicoid threads 304.
[0044] In a range where portions of other first helicoid threads
304 threadably engage with the second helicoid threads 201, the
grooves 304a are formed parallel to these portions of other first
helicoid threads 304. In a range where these portions of other
first helicoid threads 304 and the second helicoid threads 201 do
not threadably engage, i.e., in a range where these portions of
other first helicoid threads 304 extend toward the proximal end,
the grooves 304a have nonparallel regions 304b not parallel to
these portions of other first helicoid threads 304.
[0045] The nonparallel regions 304b are formed at the proximal ends
of the grooves 304a, and are bent in a direction perpendicular to
the optical axis.
[0046] The second helicoid thread 201 with the projection 203
formed thereon is inserted in the corresponding groove 304a, and
this groove 304a engages with the projection 203. In the presence
of the projection 203, the second helicoid threads 201 are not
disengaged from the deep grooves 304a.
[0047] The cam grooves 306 are formed in the inner surface 307. The
cam grooves 306 guide movement of the rear-group lens 700, and
accommodate cam followers 702 of the rear-group lens frame 701.
[0048] The cam grooves 306 have tilt regions 306a almost parallel
to the first helicoid threads 304, and perpendicular regions 306b
continuous to the proximal ends of the tilt regions 306a. The tilt
regions 306a are regions for moving the rear-group lens 700 in the
direction of optical axis upon rotation of the intermediate
cylinder 300. The perpendicular regions 306b are regions formed
perpendicularly to the optical axis. Even when the intermediate
cylinder 300 rotates, the perpendicular regions 306b do not allow
the rear-group lens 700 to move in the direction of optical
axis.
[0049] When the movable cylinder 200 is retracted in the
intermediate cylinder 300, the cam followers 702 of the rear-group
lens frame 701 are located at the perpendicular regions 306b of the
cam grooves 306. Thus, even when the intermediate cylinder 300
rotates, the rear-group lens 700 does not move relative to the
intermediate cylinder 300.
[0050] The inner surface 307 has catching portions 310. The
catching portions 310 serve to transmit the rotation force of the
intermediate cylinder 300 to a ring 5 through projections 55, and
project inward from the inner surface 307.
[0051] FIG. 5 is an exploded perspective view of a barrier
opening/closing unit.
[0052] As shown in FIG. 5, a barrier opening/closing unit 1 has
barriers 2 for opening/closing the distal-end opening of the
photographing optical system. The barriers 2 are arranged
symmetrically with respect to the optical axis O of the
photographing optical system as the center, and are rotatably
attached to a barrier main body 3. For example, the barriers 2 have
through holes 21 extending through them, and axial pins 32
projecting from a surface 31 of the barrier main body 3 are
inserted in the through holes 21. Hence, the barriers 2 are
rotatable about the corresponding axial pins 32 as the centers,
thereby opening/closing the barriers 2.
[0053] Catching portions 33 are formed in the outer edge of the
barrier main body 3. The catching portions 33 serve to catch a
front cover 4 attached to the upper surface of the barrier main
body 3. For example, the catching portions 33 are formed of
projections obtained by notching the outer edge of the barrier main
body 3, and catch cached portions 41 of the front cover 4.
[0054] Openings 34 are formed in those portions of the barrier main
body 3 which are in the vicinities of the axial pins 32. The
openings 34 are holes extending from the upper surface through the
lower surface of the barrier main body 3, and allow pins 22 formed
on the rear surfaces of the barriers 2 to extend through them.
[0055] The ring 5 is arranged on the rear side of the barrier main
body 3. The ring 5 serves to open/close the barriers 2 when it
rotates about the optical axis O as the center, and has a ring
portion 51 forming a ring-like shape. The ring portion 51 is
rotatably attached to the rear side of the barrier main body 3, and
has first and second hooks 53 and 54 at its outer edge.
[0056] One end of a coil spring 61 is caught by the first hook 53.
The other end of the coil spring 61 is caught by a pin 35 extending
from the rear surface of the barrier main body 3. With the
contracting force of the coil spring 61, the ring 5 is biased in a
constant direction, e.g., counterclockwise about the optical axis O
as the center.
[0057] One end of each coil spring 62 is caught by the
corresponding second hook 54. The other end of each coil spring 62
is caught by the pin 22 of the corresponding barrier 2 which
extends through the barrier main body 3. When the coil spring 61
biases the ring 5 to rotate counterclockwise, the other end face
54a with the hook-shaped portion of each second hook 54 abuts
against the corresponding pin 22 to urge it, thereby opening the
corresponding barrier 2. When the ring 5 rotates clockwise against
the biasing force of the coil spring 61, the pins 22 are pulled by
the contracting forces of the coil springs 62 to elastically close
the barriers 2.
[0058] Rotation force transmitting portions 52 are formed on the
outer edge of the ring portion 51 of the ring 5. The rotation force
transmitting portions 52 transmit the rotation force from the lens
barrel to the ring portion 51, and are formed integrally with the
ring portion 51 to constitute band-like bodies extending from the
ring portion 51 backward parallel to the optical axis O. The
rotation force transmitting portions 52 are not limited to
band-like bodies, but may have rod-like shapes or other shapes.
[0059] The rotation force transmitting portions 52 are formed three
almost equidistantly on the outer circumference of the ring portion
51. Regarding the number of rotation force transmitting portions
52, two or more rotation force transmitting portions 52 are
preferably formed equidistantly so the ring portion 51 can be
rotated stably.
[0060] Projections 55 are formed on the outer surfaces of the
distal ends of the rotation force transmitting portions 52. The
projections 55 are caught by the lens barrel.
[0061] The barrier opening/closing unit 1 is set such that the
barriers 2 are located at the distal end of the movable cylinder
200, as shown in FIG. 1. The rotation force transmitting portions
52 of the ring 5 are arranged along the inner surface of the
movable cylinder 200. The projections 55 formed on the distal ends
of the rotation force transmitting portions 52 abut against the
catching portions 310 formed on the inner surface of the
intermediate cylinder 300.
[0062] The operation of the lens barrel using the moving mechanism
according to this embodiment will be described.
[0063] As shown in FIG. 1, when the main switch of the camera body
800 is OFF, the intermediate cylinder 300 has been retracted in the
stationary cylinder 400, and the movable cylinder 200 has been
retracted in the intermediate cylinder 300. At this time, the
projections 55 of the rotation force transmitting portions 52 have
been rotated by the catching portions 310 of the intermediate
cylinder 300 clockwise when seen from the front side of the camera.
Hence, the ring 5 is rotated clockwise through the projections 55
and rotation force transmitting portions 52, and the barriers 2 are
closed through the coil springs 62.
[0064] When the main switch of the camera is turned on, the
intermediate cylinder 300 rotates counterclockwise when seen from
the front side. Along with this rotation, the ring 5 that has been
rotated by the intermediate cylinder 300 through the projections 55
and rotation force transmitting portions 52 is allowed to rotate.
When the intermediate cylinder 300 rotates, the ring 5 also rotates
counterclockwise. Rotation of the ring 5 opens the barriers 2.
[0065] Even when the intermediate cylinder 300 rotates, if the
rotation is within a range of a predetermined rotation or less, the
intermediate cylinder 300 is not extended from the stationary
cylinder 400, and the movable cylinder 200 is not extended from the
intermediate cylinder 300. More specifically, as shown in FIG. 3,
even when the intermediate cylinder 300 rotates, if the helicoid
threads 301 of the intermediate cylinder 300 do not threadably
engage with the helicoid threads 401 of the stationary cylinder
400, the intermediate cylinder 300 is not extended from the
stationary cylinder 400. As shown in FIG. 4, even when the
intermediate cylinder 300 rotates, if the projection 203 of the
movable cylinder 200 is located at the nonparallel region 304b of a
groove 304a of the intermediate cylinder 300, the movable cylinder
200 is not extended from the intermediate cylinder 300.
[0066] Therefore, when the intermediate cylinder 300 rotates, the
barriers 2 can be opened without extending the intermediate
cylinder 300 and movable cylinder 200, enabling photographing at
the WIDE end.
[0067] In this state, when zoom operation is performed by the
camera body 800, the intermediate cylinder 300 further rotates to
be extended from the stationary cylinder 400, and the movable
cylinder 200 is extended from the intermediate cylinder 300. This
enables telescopic photography. To end use of the camera, in
response to operation of the camera body 800, the intermediate
cylinder 300 rotates in the opposite direction and is retracted in
the stationary cylinder 400, and the movable cylinder 200 is
retracted in the intermediate cylinder 300.
[0068] As shown in FIG. 6, when the intermediate cylinder 300 is
completely retracted in the stationary cylinder 400 and the movable
cylinder 200 is completely retracted in the intermediate cylinder
300, the intermediate cylinder 300 and movable cylinder 200 do not
move in the direction of optical axis, but only the intermediate
cylinder 300 rotates.
[0069] At this time, the catching portions 310 of the intermediate
cylinder 300 abut against the projections 55, to rotate them
clockwise. Therefore, the ring 5 rotates clockwise through the
projections 55 and rotation force transmitting portions 52. Upon
rotation of the ring 5, the barriers 2 are closed.
[0070] According to this lens barrel, when the intermediate
cylinder 300 rotates, its rotation force is directly transmitted to
the ring 5 through the rotation force transmitting portions 52.
Therefore, to rotate the ring 5, no constituent components such as
a lever separate from the ring 5 need be provided, and the number
of constituent components of the apparatus can be reduced.
Accordingly, the component cost can be reduced. Since the number of
components can be reduced, the apparatus can be easily assembled
during the manufacture, reducing the manufacturing cost as
well.
[0071] Since the ring 5 has the plurality of rotation force
transmitting portions 52, the rotation force of the ring 5 is
transmitted by them. This rotation force transmission smoothly
rotates the ring 5 without being tilted. Therefore, the barriers
can be opened/closed smoothly.
[0072] As described above, according to the movable mechanism of
this embodiment, the intermediate cylinder 300 as the first
cylinder and the movable cylinder 200 as the second cylinder engage
with each other not only through the first and second helicoid
threads 304 and 201 but also through the projection 203 and groove
304a. In a range where the first and second helicoid threads 304
and 201 threadably engage with each other upon movement of the
intermediate cylinder 300 and movable cylinder 200 relative to each
other, the intermediate cylinder 300 and movable cylinder 200 can
be precisely moved relative to each other through the helicoid
mechanism comprised of the first and second helicoid threads 304
and 201. In a range where the first and second helicoid threads 304
and 201 do not threadably engage with each other, the intermediate
cylinder 300 and movable cylinder 200 can be moved relative to each
other through the projection 203 and groove 304a by relative
movement different from that by the helicoid mechanism.
[0073] In this case, in a range where the first and second helicoid
threads 304 and 201 do not threadably engage with each other, if
the grooves 304a are formed as required, movement of the
intermediate cylinder 300 and movable cylinder 200 relative to each
other can be set freely. Therefore, the amount of movement of the
intermediate cylinder 300 and movable cylinder 200 relative to each
other can be increased or decreased with respect to rotation of the
intermediate cylinder 300, or can be set to zero.
[0074] This embodiment exemplifies a moving mechanism in which the
projection 203 is formed on the outer surface of the movable
cylinder 200 and the grooves 304a are formed in the inner surface
of the intermediate cylinder 300. However, a moving mechanism
according to the present invention is not limited to this, but can
be a moving mechanism in which a projection 203 is formed on the
inner surface of an intermediate cylinder 300 and grooves 304a are
formed in the outer surface of a movable cylinder 200. Even in this
case, the operation and effect similar to those of the moving
mechanism according to the above embodiment can be obtained.
[0075] In the above embodiment, the nonparallel regions 304b of the
first helicoid threads 304 and the perpendicular regions 306b of
the cam grooves 306 are perpendicular to the optical axis O.
However, the nonparallel regions 304b and region 306b need not be
perpendicular to the optical axis O, but may be tilted with respect
to the optical axis O as required in accordance with the shape of
the barrel. Even in this case, the operation and effect similar to
those of the moving mechanism according to the above embodiment can
be obtained.
[0076] In this embodiment, the moving mechanism according to the
present invention is applied to a lens barrel for a photographic
lens in a camera. However, a moving mechanism according to the
present invention is not limited to this, but can be applied to any
other mechanism as far as it is a moving mechanism for moving a
plurality of inner and outer cylinders provided in a multiple
manner in the axial direction relative to each other.
[0077] As has been described above, according to the present
invention, the first and second cylinders engage with each other
not only through the first and second helicoid threads but also
through a projection and groove. Therefore, in a range where the
first and second helicoid threads threadably engage with each other
upon movement of the first and second cylinders relative to each
other, the first and second cylinders can be precisely moved
relative to each other through a helicoid mechanism comprised of
the first and second helicoid threads, and in a range where the
first and second helicoid threads do not threadably engage with
each other, the first and second cylinders can be moved relative to
each other through the projection and groove by relative movement
different from that by the helicoid mechanism. In this case, in the
region where the first and second helicoid threads do not
threadably engage with each other, if grooves are formed as
required, movement of the first and second cylinders relative to
each other can be set freely.
[0078] From the invention thus described, it will be obvious that
the embodiments of the invention may be varied in many ways. Such
variations are not to be regarded as a departure from the spirit
and scope of the invention, and all such modifications as would be
obvious to one skilled in the art are intended for inclusion within
the scope of the following claims.
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