U.S. patent number RE34,059 [Application Number 07/730,109] was granted by the patent office on 1992-09-08 for zooming mechanism for zoom lens.
This patent grant is currently assigned to Olympus Optical Company, Ltd.. Invention is credited to Hiroshi Akitake.
United States Patent |
RE34,059 |
Akitake |
September 8, 1992 |
**Please see images for:
( Certificate of Correction ) ** |
Zooming mechanism for zoom lens
Abstract
A zooming mechanism for a zoom lens comprises a zooming frame
disposed for translation back and forth with respect to a
stationary member in the direction of an optical axis and carrying
a focus lens group in a manner to permit its focus adjustment; a
drive for translating the zooming frame in the direction of the
optical axis, a carrier frame for carrying another zoom lens group
and supported within the zooming frame by a support member located
therein for translation back and forth in the direction of the
optical axis, a device for deriving a rotational drive in
association with the translation of the zooming frame in the
direction of the optical axis, and a device responsive to the
rotational drive to cause a non-linear movement of the carrier
frame. A rotational drive is derived in association with the
translation of the zooming frame in the direction of the optical
axis, and utilized by said non-linear moving device to cause a
non-linear movement of the carrier frame to achieve a zooming
operation.
Inventors: |
Akitake; Hiroshi (Hachioji,
JP) |
Assignee: |
Olympus Optical Company, Ltd.
(JP)
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Family
ID: |
26496615 |
Appl.
No.: |
07/730,109 |
Filed: |
July 15, 1991 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
Issue Date |
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Reissue of: |
218701 |
Jul 13, 1988 |
04948235 |
Aug 14, 1990 |
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Foreign Application Priority Data
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Jul 13, 1987 [JP] |
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62-175306 |
Jul 16, 1987 [JP] |
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62-177784 |
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Current U.S.
Class: |
359/700; 359/706;
359/826 |
Current CPC
Class: |
G02B
7/10 (20130101) |
Current International
Class: |
G02B
7/10 (20060101); G02B 015/00 () |
Field of
Search: |
;359/691,826,693,825,694,695,696,697,698,699,700,701,704,705,706
;354/195.1,195.11 |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
Primary Examiner: Ben; Loha
Attorney, Agent or Firm: Weinstein; Louis
Claims
What is claimed is:
1. A zooming mechanism for a zoom lens including a plurality of
lens groups, comprising:
a zooming frame movable in a direction of an optical axis with
respect to a stationary member and carrying at least one lens
group;
drive means for moving the zooming frame in the direction of the
optical axis;
a carrier frame carrying another zoom lens group and supported by a
support member within the zooming frame for movement back and forth
in the direction of the optical axis;
means for deriving a rotational drive responsive to the movement of
the zooming frame in the direction of the optical axis;
and means responsive to said .Iadd.means .Iaddend.for deriving a
rotational drive .[.means.]. to cause a non-linear movement of the
carrier frame.
2. A zooming mechanism according to claim 1, in which the zooming
frame comprises a hollow body and is slidably fitted in the
stationary member which also comprises a hollow body of a greater
size, the zooming frame being disposed for movement back and forth
in the direction of the optical axis while utilizing a support
shaft disposed within the stationary member in parallel
relationship with the optical axis as a guide.
3. A zooming mechanism according to claim 2, wherein said zooming
frame hollow body and said stationary member hollow body are
substantially rectangular.
4. A zooming mechanism according to claim 3, further including a
rectangular film frame arranged adjacent to said zooming
mechanism;
said zooming frame hollow rectangular-shaped body being slightly
greater in size than said film frame.
5. A zooming mechanism according to claim 4, wherein three sides of
said zooming frame hollow rectangular-shaped body are substantially
equal in length to three associated sides of said rectangular film
frame.
6. A zooming mechanism according to claim 1, in which the drive
means comprises a feed screw disposed within the stationary member
and extending in a direction parallel to the optical axis, a female
threaded bore formed in a block secured to a lower surface of the
zooming frame for threadable engagement with the feed screw, and a
rotation transmitting gear secured to the feed screw for
transmitting a rotational drive to the feed screw.
7. A zooming mechanism according to claim 1, in which the carrier
frame comprises a hollow cylindrical member of a reduced length in
which a zoom lens is carried, the carrier frame being provided with
guide openings at symmetrical positions around its outer periphery
with respect to each other through which guide members disposed
within the zooming frame extend and which also serve as rotational
stops.
8. A zooming mechanism according to claim 1, in which said means
for deriving a rotational drive comprises a first non-circular gear
which is coaxially and integrally mounted on a support shaft
extending through the zooming frame for a pinion rotatably mounted
on a lower surface of the zooming frame and meshing with a rack
which is disposed within the stationary member and extending in the
direction of the optical axis.
9. A zooming mechanism according to claim 8, in which the first
non-circular gear comprises a spur gear in the configuration of
part of a spiral having a radial distance from a pivot located at a
predetermined pivot mounting location which progressively increases
in the circumferential direction.
10. A zooming mechanism according to claim 1, in which the
responsive means for moving the carrier frame comprises a second
non-circular gear rotatably mounted within the zooming frame and
disposed in meshing engagement with a first non-circular gear of
said means for deriving a rotational drive, an elongate slot formed
in the second non-circular gear, and a drive pin fixedly mounted on
the carrier frame and fitted into the elongate slot, the rotation
of the second non-circular gear causing a displacement of the
elongate slot, whereby the drive pin is effective to move the
carrier frame.
11. A zooming mechanism according to claim 10, in which the second
non-circular gear comprises a sector gear having a radial distance
from its pivot located at a predetermined pivot mounting location
which gradually changes in the circumferential direction.
12. A zooming mechanism according to claim 1, in which said means
for deriving a rotational drive comprises a first non-circular gear
coaxially and integrally mounted on support shaft for a pulley
which is rotatably mounted on a lower surface of the zooming frame,
the pulley having one end of a cord anchored thereto which has its
other end secured to the stationary member, the pulley being urged
for angular movement to return to its original position.
13. A zooming mechanism according to claim 1, in which said
responsive means for moving the carrier frame comprises a second
non-circular gear rotatably mounted within the zooming frame and
disposed in meshing engagement with a first non-circular gear of
said means for deriving a rotational drive, a drive pin fixedly
mounted on the second noncircular gear, and an elongate slot formed
in the carrier frame and in which the drive pin is fitted, the
rotation of the second non-circular gear causing a displacement of
the drive pin which is effective through the elongate slot to move
the carrier frame.
14. A zooming mechanism according to claim 1 in which said means
for deriving a rotational drive comprises a pinion gear rotatably
mounted on a lower surface of the zooming frame and coaxially and
integrally mounted on a support shaft for a sector gear, which
meshes with a rack disposed within the stationary member and
extending in a direction parallel to the optical axis, which
extends into the zooming frame.
15. A zooming mechanism according to claim 1, in which said
responsive means for moving the carrier frame comprises a cam drive
gear rotatably mounted within the zooming frame and disposed in
meshing engagement with a pinion gear of said means for deriving a
rotational drive, a cam arm having its one end coaxially and
integrally mounted on a support shaft for the cam drive gear, an
actuator cam formed by a profiled cam formed in the cam arm, and a
drive pin fixedly mounted on the carrier frame and fitted into the
actuator cam, the rotation of the pinion gear being effective to
cause a rotation of the cam arm to move the carrier frame through
the engagement between the actuator cam and the drive pin.
16. A zooming mechanism according to claim 15, in which the cam
drive gear comprises a sector gear.
17. A zooming mechanism according to claim 1, in which said means
for moving the carrier frame comprises a cam disc rotatably mounted
within the zooming frame and integrally mounted on a support shaft
for a pinion gear of said means for deriving a rotational drive and
having an actuator cam, formed by a profiled slot, extending in the
manner of a spiral over at least a portion of one revolution, and a
drive pin fixedly mounted on the carrier frame and fitted into the
actuator cam, the rotation of the cam disc resulting from the
rotation of the pinion gear being effective to cause the carrier
frame to be moved through the engagement between the actuator cam
and the drive pin.
18. A zooming mechanism according to claim 1, in which said means
for deriving a rotational drive comprises a pinion gear rotatably
mounted within the zooming frame, a pulley secured to an end of a
support shaft for the pinion gear which extends below the zooming
frame and urged to return to its original position, and a cord
having its one end anchored to the pulley and other end secured to
the stationary member.
19. A zooming mechanism according to claim 1, in which a focus lens
group is displaceably supported by the zooming frame for
translation back and forth along the optical axis.
20. A zooming mechanism according to claim 1, in which said means
for deriving a rotational drive includes rotatable means journalled
on said zooming frame.
21. A zooming mechanism according to claim 1, in which said means
for deriving a rotational drive is rotatable about an axis which is
transverse to said optical axis.
22. A zooming mechanism for a zoom lens including a plurality of
lens groups, comprising:
a zooming frame linearly movable in the direction of an optical
axis and carrying at least one lens group;
drive means for moving said zooming frame;
a carrier frame slidably disposed within said zooming frame and
carrying another lens .[.groups.]. .Iadd.group.Iaddend.; and
means responsive to linear movement of said zooming frame for
moving said carrier frame in a non-linear manner.
23. A zooming mechanism according to claim 22, .[.wheein.].
.Iadd.wherein .Iaddend.the responsive means for moving said carrier
frame comprises means for providing a rotational output responsive
to said linear movement of the zooming frame and means responsive
to the rotational output for moving the carrier frame in a
non-linear manner.
24. A zooming mechanism according to claim 23, wherein the means
for providing a rotational output responsive to linear movement of
the zooming frame comprises a rack and cooperating pinion having a
pinion shaft for providing said rotational output.
25. A zooming mechanism to claim 23, wherein said means for
providing a rotational output responsive to linear movement of the
zooming frame comprises a pulley secured to a shaft rotatably
mounted on said zooming frame coupled between a stationary location
and the periphery of said pulley for rotating said pulley and said
shaft responsive to linear movement of the zooming frame.
26. A zooming mechanism according to claim 23, in which the means
responsive to the rotational output for moving the carrier frame in
a non-linear manner comprises a cam disk having cam means for
imparting non-linear movement to said carrier frame responsive to
rotation of said cam disk by said rotational output.
27. The zooming mechanism according to claim 23, wherein said means
responsive to the rotational output for moving the carrier frame in
a non-linear manner comprises first and second meshing gears, said
first meshing gear being rotated by said rotational output and said
second meshing gear being rotated by said first meshing gear and
including means for imparting non-linear movement to said carrier
frame.
28. A zooming mechanism according to claim 27, wherein said means
responsive to the rotational output for moving the carrier frame in
a non-linear manner comprises a cam lever rotated by said second
gear and having cam means for imparting non-linear movement to said
carrier frame.
29. A zooming mechanism according to claim 27, wherein said second
gear is a non-circular gear; and said mechanism further
comprising
means for moving said carrier frame, said carrier frame being
responsive to rotation of said second gear.
30. A zooming mechanism for a zoom lens, comprising;
a zooming frame provided on a zoom lens having a plurality of lens
groups, said frame being movable back and forth in the direction of
an optical axis with respect to a stationary member and carrying at
least one lens group in such a manner that the lens group is
movable back and forth in the direction of said optical axis;
drive means for moving said zooming frame in the direction of said
optical axis;
a carrier frame movably disposed within said zoom frame by a
support member provided in the zooming frame, said carrier frame
being movable back and forth in the direction of said optical axis
and carrying another lens group;
means for deriving a rotational drive responsive to the movement of
the zooming frame in the direction of said optical axis, said means
being rotatably supported on said zooming frame; and
means rotatably supported on said zooming frame, which is rotated
by said rotational drive for moving said carrier frame in a
non-linear manner.
31. A zooming mechanism according to claim 30, in which the drive
means comprises a feed screw disposed within the stationary member
and extending in a direction parallel to the optical axis, a female
threaded bore formed in a block secured to the lower surface of the
zooming frame for threadable engagement with the feed screw, and a
rotation transmitting gear secured to the feed screw for
transmitting a rotational drive to the feed screw.
32. A zooming mechanism according to claim 30, in which said means
for deriving a rotational drive comprises a first non-circular gear
which is coaxially and integrally mounted on a support shaft
extending through the zooming frame for a pinion rotatably mounted
on a lower surface of the zooming frame and meshing with a rack
which is disposed within the stationary member and extending in the
direction of the optical axis.
33. A zooming mechanism according to claim 32, in which the first
non-circular gear comprises a spur gear in the configuration of
part of a spiral having a radial distance from a pivot located at a
predetermined pivot mounting location which progressively increases
in the circumferential direction.
34. A zooming mechanism according to claim 30, in which the means
for moving the carrier frame comprises a second non-circular gear
rotatably mounted within the zooming frame and disposed in meshing
engagement with a first non-circular gear of said means for
deriving a rotational drive, an elongate slot formed in the second
non-circular gear, and a drive pin fixedly mounted on the carrier
frame and fitted into the elongate slot, the rotation of the second
non-circular gear causing a displacement of the elongated slot,
whereby the drive pin is effective to move the carrier frame.
35. A zooming mechanism according to claim 34, in which the second
non-circular gear comprises a sector gear having a radial distance
from its pivot located at a predetermined pivot mounting location
which gradually changes in the circumferential direction.
36. A zooming mechanism according to claim 30, in which said means
for moving the carrier frame comprises a cam drive gear rotatably
mounted within the zooming frame and disposed in meshing engagement
with a pinion gear of said means for deriving a rotational drive, a
can arm having its one end coaxially and integrally mounted on a
support shaft for the cam drive gear, an actuator cam formed by a
profiled cam formed in the cam arm, and a drive pin fixedly mounted
on the carrier frame and fitted into the actuator cam, the rotation
of the pinion gear being effective to cause a rotation of the cam
arm to move the carrier frame through the engagement between the
actuator cam and the drive pin.
37. A zooming mechanism for a zoom lens as defined in claim 30, in
which said zooming frame is linearly moved in the direction of said
optical axis by said drive means.
38. A zooming mechanism according to claim 30, in which said means
for deriving a rotational drive is rotatable about an axis which is
transverse to said optical axis.
39. A zooming mechanism according to claim 30, in which said means
for deriving a rotational drive includes rotatable means journalled
on said zooming frame. .Iadd.
40. A zooming system of a zoom lens composed of a plurality of lens
groups having a common optical axis comprising:
a zooming frame supporting at least one lens group and movable in
back-and-forth directions of the optical axis;
driving means for selectively moving said zooming frame in one of
said back-and-forth directions;
a carrier frame supporting another zoom lens group being movably
supported for back-and-forth movement along said optical axis;
intermediate driving means responsive to movement of said zooming
frame for providing a rotational output; and
means for moving said carrier frame in a non-linear manner
responsive to the rotational output of said intermediate driving
means. .Iaddend. .Iadd.41. A zooming system of a zoom lens
according to claim 40 wherein said intermediate driving means
rotates about an axis perpendicular to said optical axis. .Iaddend.
Description
FIELD OF THE INVENTION AND RELATED ART STATEMENT
The invention relates to a zooming mechanism for .Iadd.a
.Iaddend.zoom lens, in particular, to a zooming mechanism for a
zoom lens as may be used in a still camera or video camera.
A conventional zoom lens includes two or three movable lens groups,
and includes a zooming mechanism which moves such movable lens
groups back and forth in the direction of an optical axis. As is
well recognized, almost all of such mechanisms employ an
arrangement to translate a lens barrel by utilizing a cam mechanism
including a cam groove and a drive pin or pins fitted in the cam
groove.
Specifically, FIGS. 13A, 13B, 14 and 15 illustrate an example of a
typical zooming mechanism used in the prior art. A first lens
barrel 1 carries a first lens group L.sub.1, and a second lens
barrel 2 carries a second lens group L.sub.2. These lens barrels
are disposed one after another in the direction of an optical axis
0. The lens barrels have holders 1a, 1b and 2a, 2b which extend
upward and downward therefrom and through which openings 1c, 1d and
2c, 2d are formed. A pair of guide shafts 3, 4 which are disposed
to extend in parallel relationship with the optical axis on
opposite sides thereof serve as rotational stops, and these guide
shafts are tightly, but slidably fitted into the openings 1c, 1d,
2c, 2d to enable the respective lens groups L.sub.1, L.sub.2 to be
translated therealong. Drive pins 5a, 5b, 6a and 6b fixedly mounted
on the holders 1a, 1b, 2a and 2b, respectively, fit in cam slots
7a, 7b formed in a cam sleeve 7 to define a zooming mechanism. As
indicated by a developed view shown in FIG. 15, the cam slot 7a in
which the drive pins 5a, 5b are fitted is a linear skewed slot
which has a pitch angle of .alpha..sub.1 with respect to the
circumferential direction while the cam slot 7b in which the drive
pins 6a, 6b are fitted is a curved slot having a pitch angle of
.alpha..sub.2 with respect to the circumferential direction.
With the zooming mechanism mentioned above, the cam sleeve 7 may be
turned to move the first lens barrel 1 and the second lens barrel 2
back and forth in the direction of the optical axis from its wide
angle position shown in FIG. 13A to its telescoping position shown
in FIG. 13B or vice versa through the engagement between the cam
slots 7a, 7b and the drive pins 5a, 5b and 6a, 6b, respectively,
thus achieving a zooming action.
However, a conventional zooming mechanism as described above
utilizes guide shafts and a cam sleeve disposed outside the lenses,
whereby the cam sleeve exhibits an increased diameter. This
produces an undesirable, unused space as illustrated by a hatched
area in FIG. 14 as compared with the size of a picture frame 8,
standing in the way to a miniaturization of a camera. To assure a
smooth movement of the lens barrels, a plurality of cam slots are
duplicated in a cam sleeve at an equal angular interval, requiring
a complicated machining operation .[.to increase.]. .Iadd.which
increases .Iaddend.its cost. In addition, the first lens group
L.sub.1 has a greater travel relative to a travel of the second
lens group L.sub.2, whereby the pitch angle .alpha..sub.2 of the
cam slot as shown in FIG. 15 increases, requiring a greater force
to operate during the zooming operation, which is
disadvantageous.
OBJECT AND SUMMARY OF THE INVENTION
It is an object of the invention to provide a zooming mechanism for
zoom lens which is compact, which can be manufactured at a reduced
cost and which requires less force to drive, thereby eliminating
the described disadvantages of the prior art.
In accordance with the invention, a cam sleeve of an increased
diameter as used in a conventional zooming mechanism is eliminated.
Accordingly, the zooming mechanism of the invention has remarkable
features that (1) it is compact and requires a reduced number of
parts, and .Iadd.is .Iaddend.simple in arrangement to achieve a
higher accuracy; that (2) the simple construction requiring a
reduced number of parts enables the manufacturing cost to be
reduced; and that (3) a second zoom lens group .Iadd.has
.Iaddend.reduced lift, thus requiring less force to drive it. In
this manner, disadvantages of conventional zooming mechanism are
overcome in a sophisticated manner.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is an exploded, perspective view of essential parts of a
zooming mechanism for a zoom lens according to a first embodiment
of the invention;
FIGS. 2A and 2B are plan views, to an enlarged scale, specifically
illustrating the manner of operation of a first and a second
non-circular gear used in the zooming mechanism shown in FIG.
1;
FIG. 3 diagrammatically illustrates loci of movement of a focus
lens group and another lens group used in the zooming mechanism
shown in FIG. 1;
FIG. 4 is a rear view, partly in section, of a portion of the
zooming mechanism shown in FIG. 1;
FIG. 5 is an exploded, perspective view of essential parts of
another form of drive mechanism which is used to translate a
carrier frame carrying another zoom lens group used in the zooming
mechanism of the invention;
FIG. 6 is an exploded, perspective view of a further form of drive
mechanism;
FIG. 7 is an exploded, perspective view of a zooming mechanism for
zoom lens according to a second embodiment of the invention;
FIG. 8 is a rear view, partly in section, of part of the zooming
mechanism shown in FIG. 7 as assembled into a camera;
FIG. 9 diagrammatically illustrates the loci of movement of a focus
lens group and another lens group used in the zooming mechanism
shown in FIG. 7;
FIGS. 10A and 10B are plan views, to an enlarged scale, of part of
a lens drive mechanism used in the zooming mechanism shown in FIG.
7, illustrating the manner of operation thereof;
FIGS. llA and llB are plan views, to an enlarged scale, of another
form of a drive mechanism for a carrier frame which carries another
zoom lens group used in the zooming mechanism of the invention;
FIG. 12 is an exploded, perspective view of part of a further form
of the drive mechanism similar to that shown in FIGS. llA and
llB;
FIGS. 13A and 13B are cross sections of one form of a conventional
zooming mechanism for a zoom lens;
FIG. 14 is a front view of the zooming mechanism shown in FIGS. 13A
and 13B; and
FIG. 15 is a developed view of cam slots used in the zooming
mechanism shown in FIGS. 13A and 13B.
DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS
FIG. 1 is an exploded, perspective view of essential parts of a
zooming mechanism for a zoom lens according to a first embodiment
of the invention. Specifically, a zooming mechanism 10 comprises
two groups of zoom lenses. Specifically, the zooming mechanism 10
shown is arranged as consisting of two groups of zoom lenses, and
essentially comprises a zooming frame 12 including a helicoidal
screw to support a focus frame 11 which carries a focus lens group
L.sub.1 in a manner to permit a focusing adjustment and disposed
for movement in the direction of an optical axis with respect to a
stationary frame 13; a feed screw 23 rotatably mounted in the
stationary frame 13 for driving the zooming frame 12 in the
direction of the optical axis within the stationary frame 13 when
it is driven for rotation; a carrier frame 14 for another zoom lens
group L.sub.2 mounted on a pair of support shafts 26, 27 which are
disposed within the zooming frame 12 so as to extend in parallel
relationship with the optical axis for movement back and forth in
the direction of the optical axis .Iadd.and .Iaddend.within the
zooming frame 12; a pinion gear 18 rotatably mounted on the lower
surface of the bottom wall of the zooming frame 12 for meshing
engagement with a rack 17 disposed on the bottom wall of the
stationary frame 13 along its right corner and extending in a
direction parallel to the optical .[.axis and.]. .Iadd.axis, gear
18 being .Iaddend.rotatable in a plane parallel to the bottom
surface; a first non-circular gear 19 integrally and coaxially
mounted with the pinion gear 18 on the bottom surface of the
zooming frame 12; and a second non-circular gear 20 disposed for
meshing engagement with the first non-circular gear for rotation,
and having an elongate slot 20a therein which serves to provide a
translation of the carrier frame 14 in the direction of the optical
axis.
The zooming frame 12 comprises a rectangular hollow body which is
displaceably fitted inside the stationary frame 13 which also
comprises a rectangular hollow body of a greater size. A pair of
support shafts 24, 25 extend between a front wall and a rear frame
15 of the stationary frame 13 in parallel relationship with the
optical axis, and extend through a guide opening 12a formed in a
block 12e secured to the lower surface of the zooming frame 12 and
through a guide groove 12b formed in a projection on the top wall
of the zooming frame 12, thus holding the guiding frame against
rotation while allowing its translation in a back-and-forth
direction.
The carrier frame 14 for another zoom lens group has an ear in its
left, lower portion in which a guide opening 14a is formed and
another ear in its right, upper portion in which a guide groove 14b
is formed. The pair of support shafts 26, 27 extend between the
front wall of the zooming frame 12 and the rear frame 16 in
parallel relationship with the optical axis, and extend through the
guide opening 14a and the guide groove 14b, respectively, thus
holding the carrier frame 14 against rotation while supporting it
in a translatable manner back and forth in the direction of the
optical axis.
The feed screw 23 is rotatably carried by the front wall of the
stationary frame 13 and the rear frame 15 and extends in parallel
relationship with the optical axis, and engages female threads 12c
formed in the block 12e secured to the bottom wall of the zooming
frame 12 and extending in a direction parallel to the optical axis.
A portion of the feed screw 23 extends rearwardly beyond the rear
frame 15 and has a transmission gear 29 integrally mounted thereon,
which serves for transmitting rotating power to the feed screw
23.
The pinion gear 18 which meshes with the rack 17 is mounted on a
support shaft 18a which rotatably extends through an opening 12d
formed in the bottom of the zooming frame 12, and the first
non-circular gear 19 is integrally and fixedly mounted on the same
shaft while the second non-circular gear 20 which meshes with the
first noncircular gear 19 is rotatably carried by a support shaft
21 which is fixedly mounted on the bottom surface of the zooming
frame 12. The slot 20a which is elongate in the transverse
direction is formed adjacent to the shaft 21 and extends toward the
outer periphery. A drive pin 28 fixedly mounted on the bottom of
the carrier frame 14 at its left, lower ear is fitted into the
elongate slot 20a. The second non-circular gear 20 is urged to
rotate clock-wise by a torsion spring 22 which has its one end
secured to a stationary point and disposed around the shaft 21 and
having its other end extending through the gear 20 adjacent to its
one lateral edge, but the resulting rotation is normally suppressed
by meshing engagement with the first non-circular gear 19.
The operation of the zooming mechanism when zooming from the wide
angle side to the telescoping side will be described with reference
to FIGS. 2A and 2B. Initially, the pinion gear 18, the first
non-circular gear 19 which is coaxial and integral with the gear
18, and the second non-circular gear 20 which meshes with the first
gear 19 assume respective positions shown in FIG. 2A when they are
located at the wide angle side. As the feed screw 23 is driven by a
drive source, not shown, such as a motor or by a manual drive,
through the transmission gear 29 to translate the zooming frame
.[.2.]. .Iadd.12 .Iaddend.(see FIG. 1) in the forward direction,
the pinion gear 18 meshing with the rack 17 rotates clockwise as
indicated by an arrow b while moving in a .Iadd.linear
.Iaddend.direction indicated by an arrow a in FIG. 2A. This causes
the first non-circular gear 19 which is integral therewith to
rotate in the same direction, whereby its meshing second gear 20
rotates counter-clockwise as indicated by an arrow c. When the
zooming frame 12 is driven forward to its telescoping position, the
described members assume respective positions illustrated in FIG.
2B. As a result of such rotation of the second non-circular gear
20, the drive pin 28 associated with the carrier frame 14 which is
fitted into the elongate slot 20a formed in the gear 20 moves in a
non-linear manner with respect to the focus lens group L.sub.1
which moves linearly, as the zooming frame is moved forward, as
indicated by the diagram of FIG. 3, thus achieving a smooth zooming
operation. It should be understood that the configurations of the
first and the second non-circular .[.gear.]. .Iadd.gears
.Iaddend.19, 20 are precisely designed and formed based on optical
parameters of the zoom lens, achieving a movement of the lens group
L.sub.2 as designed.[.. into a camera, as viewed from the rear side
thereof.]..
It will be appreciated that when zooming from the telescoping to
the side angle side, the feed screw 23 is driven for rotation in he
reverse direction, performing a similar operation as described
above although opposite in direction.
As a result of utilizing non-circular gears in achieving a zooming
operation in the zooming mechanism of the first embodiment, it will
be noted in FIG. 4 that a viewfinder 30A, a patrone chamber 30B and
a spool chamber 30C can be designed so as to be disposed close to a
picture frame 40, allowing a substantial reduction in the size of
the entire camera. In addition, a complicated and expensive
machining of cam slots in a cam sleeve is avoided, allowing a
substantial reduction in the manufacturing cost. The movement of
the zoom lens group L.sub.2 need only be a compensation for the
movement of the focus lens group L.sub.1, and accordingly, a
support mechanism associated therewith can be compact and simple,
requiring a reduced magnitude of force to operate the camera.
In the first embodiment described above, the feed screw has been
employed to drive the zooming frame. However, it should be
understood that the drive mechanism associated with the zooming
frame is not limited to the use of the feed screw, but any other
drive mechanism such as helicoidal screw may be employed which is
capable of .[.driving.]. .Iadd.providing .Iaddend.a translational
movement. Where three or more lens groups are used, such mechanisms
can be used in a suitable combination. Character F shown in FIGS.
2A and 2B indicate a film plane.
FIG. 5 shows another form of drive mechanism for moving the carrier
frame for another lens group which can be used in a zooming
mechanism of the invention. Specifically, a drive mechanism 31 uses
a combination of a pulley 32 and a cord 33 in substitution for the
combination of the rack 17 and the pinion gear 18 shown in FIG. 1.
In other respects, the arrangement is quite similar to the zooming
frame of FIG. 1 and operates in a similar manner as before.
The pulley 32 is disposed on the bottom side of the zooming frame
12 at substantially the same position as assumed by the pinion gear
18 shown in FIG. 1, and a support shaft 32a which projects through
the bottom integrally and coaxially carries a non-circular gear 19A
which is similar to the first non-circular gear 19 shown in FIG. 1.
A cord 33 having its one end anchored to a pin 34 fixedly mounted
on the bottom of the stationary frame 13 (see FIG. 1) and its other
end anchored to the pulley 32 is disposed around this pulley, which
is urged for counter-clockwise rotation or in a direction to take
up the cord 33, by a torsion spring 35 having its one end disposed
in abutment against a stationary point and its other end secured to
the upper surface of the pulley 32.
The drive mechanism 31 operates as follows: Specifically when the
zooming frame 12 (see FIG. 1) moves in a direction indicated by an
arrow d within the stationary frame 13, the pulley 32 moves in the
same direction while rotating clockwise or in a direction indicated
by an arrow e. The first non-circular gear 19A which is integral
with the pulley 32 rotates in the same direction, whereby the
second non-circular gear 20 (see FIG. 1) which meshes with the
first non-circular gear 19A rotates counter-clockwise, thus
operating in a similar manner and achieving an effect similar to
the zooming mechanism shown in FIG. 1. The substitution of the
pulley 32 and the cord 33 for the combination of the rack 17 and
the pinion gear 18 (see FIG. 1) simplifies the construction,
reduces the space requirement and allows a reduction in the
manufacturing cost.
FIG. 6 shows another form of drive mechanism which translates the
carrier frame for another zoom lens group which may be used in the
zooming mechanism of the invention. Specifically, a drive mechanism
41 is constructed in a manner similar to the zooming mechanism
shown in FIG. 1 except for the construction of the carrier frame 14
for another lens group and of the second non-circular gear 20. In
other respects, the arrangement is quite similar to the arrangement
of FIG. 1, and operates in a similar manner.
In the drive mechanism 41, a carrier frame 14A for another lens
group has a bottom wall which extends rearwardly with an elongate
slot 42 formed in the extension and extending in a direction
substantially perpendicular to the direction of the optical axis.
Fitted into the slot 42 is a drive pin 43 fixedly mounted on the
upper surface of a second non-circular gear 20A which is similar to
the second non-circular 20 shown in FIG. 1.
It will be appreciated that the operation of the drive mechanism 41
is similar to that of the drive mechanism shown in FIG. 1 except
that the drive pin 43 and the slot 42 in which the pin is fitted
are disposed on the second non-circular gear 20A and the carrier
frame 14A, respectively, in a manner opposite from the drive
mechanism of FIG. 1. However, the operation remains the same. This
arrangement may be advantageous in facilitating the movement
depending on the manner of translation of the carrier frame
14A.
FIG. 7 is an exploded perspective view of a zooming frame for zoom
lens according to a second embodiment of the invention.
Specifically, a zooming mechanism 51 comprises two groups of zoom
lenses, and essentially comprises a stationary frame 55, a zooming
frame 54 which is slidably fitted into the frame 55 and is capable
of translating only in the direction of an optical axis, a carrier
frame 52 for a focus lens group L.sub.1 which is disposed forwardly
in the zooming frame 54 in a manner to permit a focusing
adjustment, a carrier frame 53 for another zoom lens group which is
mounted within the zooming frame 54 to permit its movement back and
forth along the optical axis, means for deriving a rotating drive
in association with the translation of the zooming frame 54 in the
direction of the optical axis, and an actuator cam 56 responsive to
the last mentioned means to cause the carrier frame 53 to translate
in the direction of the optical axis.
The zooming frame 54 comprises a rectangular hollow body having an
open rear side, and the carrier frame 52 for a focus lens group
L.sub.1 is supported in a forward portion thereof as by a
helicoidal screw in a manner to permit a focusing adjustment. The
stationary frame 55 .Iadd.similar to frame 13 .Iaddend.again
comprises a rectangular hollow body of a greater size than the
zooming frame 54, which is slidably fitted inside the stationary
frame 55. A feed screw 61 extends through a rear wall of the
stationary frame 55 at a location toward the bottom and offset to
one lateral side and threadably engages a threaded female feed bore
54b formed in a block 54d which is secured to or forms a lower
portion of the zooming frame 54. A rotation transmitting gear 61a
is secured to the other end of the feed screw 61, and may be turned
to translate the zooming frame 54 relative to the stationary frame
55 along the optical axis. A guide and support shaft 63 has its one
end secured to the rear wall of the stationary frame 55 toward the
bottom and extends parallel to the feed screw 61. The other end of
the shaft 63 extends into a lead opening 54c formed in the zooming
frame 54 adjacent to the female threaded bore 54b. A support shaft
67 has its one end secured to the stationary frame 55 at the left,
top corner and its .[.oher.]. .Iadd.other .Iaddend.end is fitted
into an anti-rotation groove 54a formed in a block mounted on top
of the zooming frame 54 toward its left side. In this manner, a
translation of the zooming frame 54 with respect to the stationary
frame 55 can take place without any oscillation.
The carrier frame 53 which carries another zoom lens group L.sub.2
and is disposed within the zooming frame 54 comprises a hollow
cylindrical body of a reduced length, which is provided with an
anti-rotation groove 53b around its outer periphery at a right,
upper portion and is also provided with a guide opening 53a which
is also formed around the outer periphery at a left, lower portion
or at a symmetrical position with respect to the groove 53b. Guide
shafts 65, 64, which also serve as rotational stops, are
.[.fixed.]..Iadd.fixedly .Iaddend.mounted on the zooming frame 54
and extend in parallel relationship with the optical axis and are
closely fitted in the groove 53b and the opening 53a, thus locking
the carrier frame 53 against rotation and preventing its
oscillation during its translation in the direction of the optical
axis.
The means which derives a rotational drive in .[.associated.].
.Iadd.association .Iaddend.with the translation of the zooming
frame 54 in the direction of the optical axis is constructed to
derive a rotational drive by its operation in a plane parallel to
the optical axis. It comprises a rack 60 disposed on the bottom
wall of the stationary frame 55 at its left corner and extending
parallel to the optical axis and a sector gear 59 rotatably mounted
on the underside of the bottom of the zooming frame 54 for meshing
engagement with the rack 60. The sector gear 59 has a support shaft
58a which extends into the zooming frame 54 by passing through the
bottom wall thereof, with a pinion gear 58 integrally mounted on
the top end thereof. The gear 58 is disposed in meshing engagement
with a cam drive gear 57 which comprises a sector gear.
The actuator cam 56 comprises a cam arm having a profiled slot
therein, with its one end rotatably mounted on a support shaft 66
which is fixedly mounted on the bottom wall of the zooming frame 54
in an integral manner with the cam drive gear 57 which meshes with
the gear 58 as indicated in FIG. 8. The actuator cam 56 is urged
.[.of.]. .Iadd.into .Iaddend.clockwise rotation by a torsion spring
62 and having its central portion disposed around the shaft 66
.Iadd.and having its .Iaddend.one end anchored to a stationary
point and having its .[.its.]. other end engaged with the lateral
side of the cam 56. Adjacent to its free end, the actuator cam 56
is formed with a profiled slot 56a which is configured as a part of
an arc, in which is fitted a drive pin 53c fixedly mounted on the
carrier frame 53 on its bottom surface toward the left side
thereof.
The operation of the zooming mechanism 51 when driving from the
wide angle to the telescoping side will now be described with
reference to FIGS. 7, 10A and 10B. When the feed screw 61 is turned
by a drive source, not shown, (which may be an electric motor or a
manual drive or the like), its engagement with the female threaded
bore 54b drives the zooming frame 54 in the forward direction with
respect to the stationary frame 55, thus advancing the focus lens
group L.sub.1. This movement causes the sector gear 59 which meshes
with the rack 60 to rotate counter-clockwise, whereby the pinion
gear 58 which is integrally mounted on the shaft 58a rotates in the
same direction, causing the cam drive gear 57 which meshes
therewith to rotate clockwise thereupon. Thereupon, the actuator
cam 56 which is integral with the cam drive gear 57 rotates in the
same direction, changing from its condition illustrated in FIG. 10A
to a condition shown in FIG. 10B. Such rotation of the actuator cam
56 is effective to cause the guide pin 53c on the carrier frame 53
which is fitted into the profiled slot 56a in the actuator cam 56
to move therealong, thus causing the other zoom lens group L.sub.2
to advance forward at the same time as the focus lens group L.sub.1
moves in accordance with the optical design, achieving a zooming
operation as illustrated in FIG. 9. When changing from the
telescoping to the wide angle side, the operation occurs in an
opposite manner. A reference character F shown in .[.FIG..].
.Iadd.FIGS. .Iaddend.10A and 10B indicates a photographic film.
FIG. 8 shows the zooming frame 51 assembled into a camera, as
viewed from the rear side thereof. It will be apparent by
comparison of this FIG. with the conventional zooming mechanism
employing a cam sleeve or the like as illustrated in FIGS. 13A, 13B
to 15, there is no extension of the frame which projects beyond the
picture frame 40, allowing the viewfinder 30A, the patrone chamber
30B and the spool chamber 30C to be disposed very close to the
picture frame 40, allowing a substantial reduction in the overall
size of the camera while simultaneously avoiding a troublesome
meshing operation of forming a cam slot in a cam sleeve to thereby
permit a substantial reduction in the manufacturing cost. It is to
be understood that a mechanism which drives the zooming frame 54 is
not limited to a feed screw mechanism, but any other drive
mechanism such as a helicoidal screw may also be used. In addition,
the invention is equally applicable to a zoom lens having three or
four lens groups.
FIGS. 11A and 11B show another form of drive mechanism which causes
a translation of a carrier frame carrying another lens group which
may be used in the second embodiment. Specifically, a drive
mechanism 71 comprises a single disc-shaped cam plate 72 which
serves the combination of the actuator cam 56 and the cam drive
gear 57, and a pinion gear 58 which is integral with the cam plate
and which meshes with the rack 60. In other respects, the
arrangement is similar to the previous drive mechanism. The cam
plate 72 is formed with a spirally extending profiled slot 73 which
extends from a point close to the center substantially through one
revolution, with a guide pin 53c on the carrier frame 53 (see FIG.
7) being fitted into the profiled slot 73.
The drive mechanism 71 is also effective to achieve a smooth
operation of the carrier frame 53 in a manner similar to the
zooming frame 51 shown in FIG. 7. Specifically, when the feed screw
61 associated with the stationary frame 55 (see FIG. 7) is driven
to cause the zooming frame 54 to advance forward, the engagement
between the rack 60 and the pinion gear 58 is effective to move the
cam plate 72 in a direction indicated by an arrow a.sub.o while
causing the rotation indicated by an arrow b.sub.o, as shown in
FIG. llA. Accordingly, the guide pin 53c which fits in the slot 73
moves in a direction indicated by an arrow c.sub.o. As a result of
a forward movement of the zooming frame 54, the cam plate 72 turns
from a position illustrated in FIG. llA to a position illustrated
in FIG. llB while causing the guide pin 53c to move forward, thus
advancing the carrier frame 53. In this manner, both lens groups
can be advanced through given strokes as with the zooming frame 51
shown in FIG. 7 from the wide angle to the telescoping side. When
zooming in the opposite direction, the operation takes place in an
opposite procedure.
FIG. 12 shows a further form of drive mechanism which causes
translation of the carrier frame for another zoom lens which may be
used in the second embodiment. Specifically, a drive mechanism 81
comprises a pulley 82 which is rotatable in an integral manner with
the pinion gear 58, and a cord 83 having its one end anchored to
the pulley 82 and its other end looped around a pin 84 which is
fixedly mounted on a stationary member, the both of which are
substituted for a combination of the sector gear 59 and the rack 60
shown in FIG. 7. The pulley 82 is rotatably mounted in coaxial
relationship and integral with the gear 58 at the location where
the sector gear 59 is disposed in the arrangement of FIG.7. In
other respects, the zooming mechanism is constructed in the same
manner as shown in FIG. 7.
The drive mechanism 81 operates as follows: Since the gear 58 is
urged for counter-clockwise rotation (indicated by an arrow
f.sub.o) by the torsion spring 62 (see FIG. 7), it will be seen
that as the zooming frame 54 translates in a direction indicated by
an arrow e.sub.o, the pulley 82 rotates in the same direction or
counter clockwise, causing the gear 58 to rotate the cam drive gear
57 (see FIG. 7) and its integral actuator cam 56 clockwise, thus
driving the carrier frame which carries another zoom lens group
entirely in the same manner as the zooming mechanism 51 shown in
FIG. 7. When the zooming frame 54 is translated in the opposite
direction, the pulley 82 and the gear 58 rotate in the opposite
direction, again operating in the same manner as the zooming
mechanism 51 with .[.the.]. .Iadd.a .Iaddend.similar effect. In the
drive mechanism 81, the replacement of the rack 60 by the cord 83
simplifies the construction, requires less space requirement and
allows a substantial reduction in the manufacturing cost.
* * * * *