JP2002236243A - Lens barrel - Google Patents

Abstract

(57) [Summary] In a lens barrel having at least two lens groups that are relatively moved, the position accuracy and the optical performance of the lens groups are increased while the manufacturing cost is suppressed. A first lens holding ring having a first lens group is rotatably supported by the first lens holding ring in a lens barrel having first and second lens groups moving relatively. A second lens holding ring having a second lens group and located between an inner surface of the rotating ring and an outer surface of the first lens holding ring; an outer surface of the first lens holding ring and a second A linear guide groove having a bottom parallel to the optical axis and a linear guide protrusion movably fitted in the linear guide groove having a bottom formed on one and the other of the inner surfaces of the lens holding ring; A cam projection and a follower projection which are formed on one and the other of the outer surfaces of the two lens retaining rings and engage with each other; and the first lens retaining ring, the second lens retaining ring, and the rotating ring are respectively provided in a radial direction. Complete ring without penetrating part.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

TECHNICAL FIELD The present invention relates to a lens barrel.

[0002]

2. Description of the Related Art In a lens barrel, a mechanism for relatively moving a plurality of lens groups in an optical axis direction via a rotating cam ring is frequently used. Such things are common. A straight guide ring is provided inside the cam ring, and a lens holding ring is further provided inside the guide ring. A cam groove is formed on the inner peripheral surface of the cam ring, and a through-hole for straight-moving guide penetrated in the radial direction is formed in the straight-moving guide ring. The lens holding ring has a rectilinear guide protrusion and a roller (follower) at the same position in the circumferential direction. The rectilinear guide protrusion fits into a through hole of the rectilinear guide ring, and the roller passes through the through hole into a cam groove of the cam ring. I'm stuck. Then, when the cam ring rotates, the lens holding ring that has been guided linearly advances and retreats in the optical axis direction along the cam groove due to the relationship between the cam groove and the roller.

[0003] In order to obtain high optical performance with a lens barrel, it is desirable not to provide a through portion in the radial direction in the barrel component. That is, if a portion such as the above-described straight guide through hole is formed, the dimensional accuracy at the time of molding is likely to be affected, and the lens group is tilted or eccentric with respect to the optical axis, or is displaced in the front-back (optical axis) direction. There is a risk. In order to avoid such inconveniences, it is conceivable to form the lens barrel constituent member from a metal material, but the manufacturing cost increases. Further, when the penetrating portion is formed, harmful light or foreign matter may pass through the penetrating portion, and optical performance may be impaired.

When the cam ring is formed as a molded product of synthetic resin or the like, a draft is formed on the inner surface of the cam groove due to the necessity of die cutting, and the cross section of the cam groove is generally trapezoidal. is there. However, in the cam groove having such a shape, since the cam surface for guiding the roller is not a vertical surface parallel to the axial direction of the roller but an inclined surface, it is difficult to obtain the fitting accuracy with the roller. In addition, there is a possibility that backlash may occur in the advancing / retreating direction (optical axis direction) or the radial direction of the lens, or light may leak from a fitting portion between the cam groove and the roller. In order to avoid this, it is conceivable that the cam ring is made of metal instead of a resin molded product to improve the accuracy, or the shape of the roller side is devised, but the manufacturing cost is increased. Further, conventionally, the roller is formed separately from the lens holding ring and then fixed to the lens holding ring, causing an increase in manufacturing cost.

[0005]

SUMMARY OF THE INVENTION The present invention provides at least two
In a lens barrel having two lens groups, an object is to improve the positional accuracy and optical performance of the lens groups while suppressing manufacturing costs.

[0006]

SUMMARY OF THE INVENTION The present invention relates to a lens barrel having first and second lens groups which move relative to each other, wherein a first lens holding ring having a first lens group; A rotating ring freely supported and driven to rotate; located between an inner surface of the rotating ring and an outer surface of the first lens holding ring;
A second lens holding ring having a second lens group; a bottomed rectilinear guide groove formed on one or the other of the outer surface of the first lens holding ring and the inner surface of the second lens holding ring and parallel to the optical axis. And a linear guide protrusion movably fitted in the bottomed linear guide groove; and
A cam projection and a follower projection which are formed on one and the other of the inner surface of the rotating ring and the outer surface of the second lens holding ring; Each of the rings is a complete ring having no penetrating portion in the radial direction.

The cam projection has a long rib shape having a substantially rectangular cross section.
The follower projection is preferably a pair of cylindrical projections sandwiching the long rib-shaped cam projection. Preferably, the cam projection and the follower projection are engaged with each other in a linear engagement region substantially parallel to the lens barrel radial direction.

In the lens barrel of the present invention, the first lens holding ring, the second lens holding ring, and the rotating ring are each preferably a molded member made of synthetic resin. As a result, manufacturing costs can be reduced. In particular, it is desirable that the cam projection and the follower projection are formed integrally with one and the other of the rotating ring and the second lens holding ring. Further, it is desirable that the straight guide projection is formed integrally with the first lens holding ring or the second lens holding ring.

A structure for connecting the first lens holding ring and the rotating ring so as to be relatively rotatable includes a bottomed bottom formed in one and the other of the first lens holding ring and the rotating ring in a circumferential direction. It is preferable to form a circumferential groove and a rotation guide protrusion movably fitted in the bottomed circumferential groove.

The first lens holding ring and the rotating ring are connected by a circumferential groove having a bottom formed in a circumferential direction and a rotation guide projection movably fitted in the circumferential groove having the bottom. Is preferred.

The lens barrel of the present invention is suitable for a zoom lens barrel, and the first and second lens groups can be configured to form part of a zoom lens. The zoom lens barrel further includes an externally rotatable zoom operation ring; rotated by the zoom operation ring to move a lens group different from the first and second lens groups in the optical axis direction. Another cam ring; and a rotation guide projection provided on the rotation ring and receiving a rotational force by engaging the cam ring; the rotation ring rotates in response to a rotation operation of the zoom operation ring. It is preferable that the first and second lens groups are relatively moved.

[0012]

BEST MODE FOR CARRYING OUT THE INVENTION

DESCRIPTION OF THE ZOOM LENS COLUMN APPLIED TO THE PRESENT INVENTION As shown in FIGS. 1 and 2, a zoom lens barrel according to this embodiment has a first lens unit L1 and a second lens unit L2 in order from the object side. , A four-unit zoom lens having a third lens unit (first lens unit) L3 and a fourth lens unit (second lens unit) L4, and a first unit frame 11, a second unit frame 12, and a It is supported by a third group frame (first lens holding ring) 13 and a fourth group frame (second lens holding ring) 14. At the time of zooming, all the lens groups move straight in the optical axis direction while changing the air gap between them. The second lens unit L2 is a focusing lens unit at the same time, and moves in the optical axis direction with rotation only during focusing.

FIG. 12 is a schematic diagram showing main lens barrel constituent members as blocks to facilitate understanding of the power transmission path of the zoom lens barrel according to the present embodiment. In the figure, an uppercase letter (S) in parentheses after the number following the member name indicates that the member is fixed, and (L) indicates that the member moves straight in the optical axis direction. R
L) indicates that it moves in the optical axis direction while rotating. In the same figure, an arrow connecting between boxes indicating members indicates that a member on the base side of the arrow guides a member on the tip side of the arrow in the optical axis direction in a straight line. The broken lines that are connected indicate that the members are connected to each other so that they can rotate relative to each other and cannot move relative to each other in the optical axis direction. Further, in the same figure, a box with oblique hatching positioned between members indicates a lead or cam mechanism for moving one member forward and backward in the optical axis direction by rotating one member, and a horizontal hatching (horizontal hatching). The box marked with indicates a rotation transmission mechanism that transmits the rotation of one member to the other.

The fixed side member of the zoom lens barrel is a mount ring 15 attached to and detached from the mount 41 of the single-lens reflex camera body 40, and an outer fixed cylinder fixed to the mount ring 15 and partially exposed to the outside diameter. 16 and also mount ring 1
5 is an inner fixed cylinder 17 that is not exposed. The outer fixed cylinder 16 supports a focus operation ring (MF operation ring) 18 and a zoom operation ring 19 which are positioned at the front and rear sides thereof, both restrict the position in the optical axis direction and freely rotate only. .

The rear end of the coupler ring 20 faces the rear end surface of the mount ring 15 at a specific position in the circumferential direction. The coupler gear 20 extends in a direction parallel to the optical axis, penetrates the rear end face of the mount ring 15 and the inner flange 16a at the rear end of the outer fixed cylinder 16, and the gear portion 20a is connected to the inner flange 1a.
6a. As is well known, when the mount ring 15 is mounted on the mount 41 of the camera body 40, the coupler gear 20 meshes with the coupler gear 42 on the camera body 40 side and is driven to rotate by the rotation of the body side coupler gear 42.

On the inner flange 16a of the outer fixed cylinder 16,
Sector gear 2 meshing with gear portion 20a of coupler gear 20
A focus gear 21 having 1a is supported so as to be capable of reciprocating rotation at a fixed angle. This focus gear 21
As shown in FIG. 4 and FIG. 5, the introduction recesses 21b of a plurality (three in the figure) of retaining protrusions 16b on the outer fixed cylinder 16 side are provided.
And an arc-shaped groove 21c that allows the retaining projection 16b to rotate at a fixed angle, and rotates forward and backward at a fixed position relative to the outer fixed cylinder 16 by a forward / reverse rotation of the gear portion 20a. That is, the rotation of the coupler gear 20 is transmitted to the focus gear 21. In the use state of the present zoom lens barrel, each of the retaining projections 16b corresponds to the corresponding introduction recess 2.
It does not move to 1b, and the retaining projection 16b maintains a state of being completely engaged with the arc groove 21c.

The focus gear 21 has a circumferential 1
A focus lever insertion groove 21d is formed at several places. The focus lever insertion groove 21d has a radial portion 22a of the focus lever 22 shown in a simple shape in FIG.
Fits. The focus lever 22 has a radial portion 22a.
Outer diameter arm 2 extending forward from the outer diameter side in a direction parallel to the optical axis
2b and an inner diameter arm 22c extending forward from the inner diameter side of the radial portion 22a in a direction parallel to the optical axis. The outer diameter arm 22b is fixed to the focus operation ring 1 by a fixing screw 22d.
8 is fixed to the inner surface. The inner diameter arm 22c is engaged with the rotation transmitting arm 12a fixed to the second group frame 12 so as to be capable of relative movement in a direction parallel to the optical axis, and transmits the rotation of the focus lever 22 to the second group frame 12 (FIG. 3). The rotation transmitting arm 12a is a lever-shaped member having a forked portion for receiving the inner diameter arm 22c in a part thereof. Therefore, the focus operation ring 18 and the focus gear 21 always rotate equally. That is, when the focus gear 21 is rotated via the coupler gear 20, the focus operation ring 18 also rotates together, and when the focus operation ring 18 is manually rotated, the focus gear 21 rotates together, In any case, the second group frame 12 (second lens group L2) is rotated via the inner diameter arm 22c and the rotation transmission arm 12a.

As shown in FIG. 7, the inner fixed cylinder 17 is formed with a through hole 17a through which the focus lever 22 is rotatably inserted. A plurality of (three in the figure) lead projections 17b are formed on the outer peripheral surface of the inner fixed cylinder 17 and are inclined with respect to the optical axis direction and the circumferential direction. It engages (is sandwiched) with a pair of lead followers 23 a formed on the inner surface of the ring 23. The cam ring 23 has, on its outer peripheral surface, a plurality (three in the figure) of lead projections 23b whose inclination direction is opposite to that of the lead projections 17b.
Lead recess 11a formed on a part of the inner peripheral surface of first group frame 11
Are fitted so as to be relatively movable with respect to. In addition, inner fixed cylinder 1
7, a plurality (three in the figure) of linear guide recesses 17c are formed on the inner peripheral surface thereof in a direction parallel to the optical axis. It is fitted on a straight guide projection 24a formed on the surface in a direction parallel to the optical axis. Further, on the outer peripheral surface of the second group moving frame 24, a plurality of (three in the figure) straight guide projections 24b different from the straight guide projections 24a are formed.
Are linear guide recesses 11 formed on the inner peripheral surface of the first group frame 11.
b.

The straight guide recess 17c of the inner fixed cylinder 17 described above.
And the linear guide protrusion 24a of the second group moving frame 24, and the linear guide recess 24b of the first group frame 11 in the second group. The rotation of the group moving frame 24 and the first group frame 11 is restricted with respect to the inner fixed cylinder 17 and is supported so as to be movable in the optical axis direction. That is, the first group frame 11 and the second group moving frame 24 are non-rotating linear members.

A plurality (three in the figure) of rotation guide projections 23c are formed on the inner surface of the distal end portion of the cam ring 23. Each of the rotation guide protrusions 23c is fitted into the circumferential groove 24c of the second group moving frame 24 so as to be relatively rotatable and not to move relatively in the optical axis direction. That is, the cam ring 23 is
It is a member that moves together with the group moving frame 24 in the optical axis direction and can rotate relative to the second group moving frame 24. The circumferential groove 24c has a plurality of protrusion entrances 24e (three in FIG. 7, FIG.
Reference), but in the use state of the zoom lens barrel,
Each rotation guide protrusion 23c does not move to the position of the corresponding protrusion entrance 24e, and is completely fitted in the circumferential groove 24c.

The cam ring 23 has a rotation transmission groove 23d formed in a part of the inner peripheral surface thereof in a direction parallel to the optical axis.
A zoom lever 26 (FIGS. 1 and 2) fixed to the inner peripheral surface of the zoom operation ring 19 is capable of relative movement in the optical axis direction and the rotation of the zoom operation ring 19 is transmitted to the rotation transmission groove 23d. It fits. The shape of the zoom lever 26 is similar to that of the focus lever 22. When the cam ring 23 is rotated, the cam ring 23 is extended in the optical axis direction due to the engagement between the lead follower 23a and the lead protrusion 17b. While the zoom operation ring 19 rotates at a fixed position, the cam ring 23 that rotates similarly to the zoom operation ring 19 involves an advancing and retreating operation in the optical axis direction. Then, the second group moving frame 24
Moves together with the cam ring 23 in the optical axis direction due to the engagement relationship between the circumferential groove 24c and the rotation guide protrusion 23c.
Does not rotate. FIG. 8 is a single item view of the cam ring 23 viewed from the optical axis direction.

As shown in FIGS. 1 and 2, a follower projection 24d is formed on the inner peripheral surface of the second group moving frame 24. The follower projection 24d is formed on the outer peripheral surface of the second group frame 12. It fits into the formed lead groove (or cam groove) 12b. When rotation is given to the second group frame 12 via the focus operation ring 18 or the coupler gear 20, the second group frame 12 (the second lens group L2) is formed according to the relationship between the lead groove (or cam groove) 12b and the follower projection 24d. ) Advances and retreats in the optical axis direction to perform focusing. On the other hand, when rotation is given to the cam ring 23 via the zoom operation ring 19, the relative rotation between the second group frame 12 and the second group moving frame 24 does not occur, and therefore, the second group frame 12 ( The second lens unit L2) is given only a linear movement for zooming in the optical axis direction. Further, the first group frame 11 (first lens group L1)
When the cam ring 23 rotates via the zoom operation ring 19, the cam ring 23 moves straight in the optical axis direction according to the relationship between the lead projection 23b and the lead recess 11a and the relationship between the straight guide recess 11b and the straight guide projection 24b.

As described above, the first lens unit L1 and the second lens unit L
For zooming given to lens unit 2 and second lens unit L2
Is understood for focusing. next,
A mechanism for giving a zooming operation to the third lens unit L3 and the fourth lens unit L4 will be described.

A fourth-group cam drive lever 28 is fixed to the rear end of the cam ring 23. The fourth-group cam drive lever 28 passes through an escape groove 17d formed in the inner fixed cylinder 17 and is internally fixed. It extends to the inner diameter side of the cylinder 17. Inner fixed cylinder 17
Further, a plurality of (three in the figure) through guide holes 17f are formed in the direction parallel to the optical axis for indirectly guiding the third group frame 13 straight.

The third group moving frame 2 is provided in each through guide hole 17f.
And a pair of followers 27a which also serve as a straight guide formed at 7
(See FIGS. 1 and 9). Third group moving frame 27
Is movably fitted to the inner diameter of the inner fixed cylinder 17, and the movement direction is regulated in the optical axis direction by the through guide hole 17f and the follower 27a. Follower 27 that makes a pair
a, a cam projection 2 formed on the inner peripheral surface of the cam ring 23.
When the cam ring 23 rotates, the third group moving frame 27 advances and retreats in the optical axis direction without rotating according to the shape of the cam projection 23f.

Third group frame 13 supporting third lens unit L3
Is fixed to the third group moving frame 27 with the diaphragm blade and the aperture opening / closing ring 30 sandwiched between the third group moving frame 27 and the diaphragm supporting annular portion 27b of the third group moving frame 27. Moves forward and backward along the optical axis. As shown in FIGS. 10 and 11, on the outer peripheral surface of the third group frame 13, a plurality of (three in FIG. 3) straight guide projections 13 a in a direction parallel to the optical axis and the circumferential groove 1 are provided.
3b are formed. Each straight guide projection 13a has
The straight guide groove 14a formed on the inner peripheral surface of the fourth group frame 14 supporting the fourth lens group L4 is fitted, and
Are guided to the third group frame 13 in a straight line.

On the other hand, a cam ring (rotating ring) 29 for the fourth group is rotatably fitted on the outer peripheral surface of the third group frame 13. Specifically, a rotation guide projection 29a protruding from the inner surface of the distal end portion of the fourth group cam ring 29 is fitted into the circumferential groove 13b of the third group frame 13 so as to be rotatable only. That is, the fourth group cam ring 29 can freely rotate relative to the third group frame 13 and moves together with the third group frame 13 in the optical axis direction. A plurality (three in the figure) of convex cams (cam protrusions) 29b are formed on the inner peripheral surface of the fourth group cam ring 29, and each convex cam 29b is formed on the outer peripheral surface of the fourth group frame 14. Engages (sandwiches) a pair of follower projections 14b formed in
When the group cam ring 29 rotates, the fourth group frame 14 advances and retreats in the optical axis direction.

When assembling the third group frame 13, the fourth group frame 14, and the fourth group cam ring 29, first, the fourth group cam ring 29 is moved so that the convex cam 29b and the follower projection 14b are engaged. Combine with 14. Subsequently, the combined body of the fourth group cam ring 29 and the fourth group frame 14 is moved in the axial direction, and the rotation guide projection 29a of the fourth group cam ring 29 is provided on the third group frame 13 side. It is inserted into the circumferential groove 13b through the inlet portion 13c, and at the same time, the linear guide groove 14a of the fourth group frame 14 is inserted into the linear guide protrusion 13a of the third group frame 13. At this point, 4
The group frame 14 is guided straight by the third group frame 13. Further, when the fourth group cam ring 29 is rotated by a predetermined amount so that the rotation guide protrusion 29a is separated from the protrusion entrance portion 13c and completely engages with the circumferential groove 13b, the follower protrusion 14b moves with respect to the convex cam 29b. Engage in the use area for zooming.
Although the third group frame 13 and the fourth group cam ring 29 rotate relative to each other with zooming, the rotation guide projection 29a always fits completely in the circumferential groove 13b in the relative rotation angle range during use. And does not move to the position of the projection inlet 13c.

The fourth group cam ring 29 is formed with a rotation transmitting arm 29c projecting radially outward, and the fourth group cam drive fixed to the cam ring 23 is formed on the rotation transmitting arm 29c. The lever 28 is engaged integrally with the rotation direction so that relative movement in the optical axis direction is possible. Therefore, the zoom operation ring 1
9 is rotated to transmit the rotation from the cam ring 23 to the fourth group cam ring 29 from the fourth and fourth group cam drive levers 28, the third group moving frame 27 is moved by the relationship between the cam projection 23f and the follower 27a.
The (third group frame 13, third lens group L3) moves in the optical axis direction, and the fourth group frame 14 (fourth lens group L4) moves in the optical axis direction due to the relationship between the convex cam 29b and the follower protrusion 14b. Thus, a movement locus for zooming can be obtained.

The overall operation of the zoom lens barrel will be briefly described with reference to FIG. At the time of zooming, when the zoom operation ring 19 is rotated, the rotation is transmitted to the cam ring 23. The cam ring 23 moves in the optical axis direction while rotating according to the guide mechanism (17b, 23a) disposed between the cam ring 23 and the inner fixed cylinder 17. As a first operation due to the movement (rotation and movement in the optical axis direction) of the cam ring 23, the second group moving frame 24 also moves in the optical axis direction. At this time, since the second group moving frame 24 is not rotated, the guide mechanisms (12b, 24d) disposed between the second group moving frame 24 and the second group frame 12 do not substantially function, and the second group frame 12 is rotated without rotating. 2nd group movement frame 24
Moves in the optical axis direction together with. In addition, as a second action by the movement of the cam ring 23, the first group frame 11 is moved along a predetermined locus in the optical axis direction according to the guide mechanism (11a, 23b) on the outer peripheral side of the cam ring 23. Further, as a third action by the movement of the cam ring 23, the third group frame 13 is moved along a predetermined path in the optical axis direction according to the guide mechanism (23f, 27a) on the inner peripheral side of the cam ring 23. Further, the cam ring 23
As a fourth action due to the movement of, the rotational force is transmitted to the cam ring 29 for the fourth group, and according to the guide mechanisms (29b, 14b) arranged between the cam ring 29 for the fourth group and the fourth group frame 14, The fourth group frame 14 moves along the optical axis in a predetermined trajectory with respect to the third group frame 13. As described above, when the zoom operation ring 19 is rotated, the first lens unit L1, the second lens unit L2, the third lens unit L3, and the fourth lens unit L4 move along a predetermined trajectory in the optical axis direction, respectively. The distance can be changed. That is, each element shown above the one-dot chain line in FIG. 12 constitutes a zoom-system drive mechanism. In addition, the guide mechanism in the above description may be a mechanism that imparts either linear or non-linear movement, and specifically, may be an arbitrary lead or cam.

For focusing, the focus operation ring 18 is used.
This is executed by inputting a rotational force to one of the coupler gear 20 and the coupler gear 20. When the focus lever 22 is moved (rotated) in the circumferential direction around the optical axis by the rotational force from any of these paths, the rotation is transmitted to the second group frame 12.
Then, according to the guide mechanism (12b, 24d) between the second group frame 12 and the second group frame 24, the second group frame 12 rotates in the optical axis direction while relatively rotating with respect to the second group frame 24. Relative movement and focusing are performed. That is, FIG.
2 and each element shown below the dashed line in the second group frame 1
The guide mechanism (12b, 24) between the second group moving frame 24 and the second group moving frame 24
d) constitutes the drive mechanism of the focus system.

[0032]

As described above, in the zoom lens barrel according to the present embodiment, during zooming, all the lens units move straight in the optical axis direction while changing the air gap between them. In particular, the third lens unit L3 and the fourth lens unit L4 change the air spacing in order to perform aberration correction at each focal length, and have high sensitivity with respect to tilting, eccentricity, or change in the longitudinal spacing, and the entire lens system. Since the influence on the optical performance is large, the precision required for the drive mechanism and the support mechanism is high. As described below, in the zoom lens barrel according to the present embodiment, the mechanism for relatively moving the third lens unit L3 and the fourth lens unit L4 does not affect the lens position accuracy or the optical performance. Have been.

First, the third lens unit L3 and the fourth lens unit L
Each of the third group frame 13, the fourth group frame 14, and the fourth group cam ring 29 related to the relative movement of the fourth group 4 is formed as a complete ring having no penetrating portion in the radial direction. In particular,
The third lens group L3 and the fourth lens group L4 are relatively moved in the optical axis direction by the rotation of the fourth group cam ring 29. The cam mechanism for performing this relative movement is one of the fourth group cam rings 29. It comprises a convex cam 29b formed integrally on the peripheral surface and a follower projection 14b formed integrally on the outer peripheral surface of the fourth group frame 14. The fourth group frame 14 is guided linearly in the optical axis direction via the third group frame 13, and the linear guide mechanism includes a linear guide protrusion 13 a integrally formed on the outer peripheral surface of the third group frame 13.
And a bottomed straight guide groove 14a formed by partially removing the inner peripheral surface of the fourth group frame 14. In other words, the third group is located inside and outside the fourth group frame 14 in the lens barrel radial direction.
After disposing the group frame 13 and the cam ring 29 for the fourth group, respectively, the components of the cam mechanism provided between the fourth group frame 14 and the cam ring 29 for the fourth group are all formed as projections, and the fourth group frame 14 is formed. And third group frame 1
Since the components of the linear guide mechanism provided between 3 are made up of bottomed grooves and projections, there is no need for a radial penetrating portion. Further, since the third group frame 13 and the fourth group cam ring 29 are relatively rotatably connected to each other, the bottom group has the bottomed circumferential groove 13b and the rotation guide projection 29a. Absent.

In this embodiment, the third group frame 14 and the fourth group frame 14
The cam ring 29 for the fourth group is formed of a molded product made of a synthetic resin. However, since no penetrating portion is formed in each member, deformation is less likely to occur during molding even when each is formed as a molded product. A member excellent in dimensional accuracy and strength can be obtained. That is, it is easy to prevent the third lens unit L3 and the fourth lens unit L4 from falling down, eccentric, or misaligned in the front-rear space without using a metal material that increases the manufacturing cost. Furthermore, if there is no radial penetration part, there is no risk of light leaking from the penetration part or foreign matter entering the optical path, and a decrease in optical performance can be prevented.

Further, since the cam mechanism does not have the bottomed groove as well as the penetrating portion, it further contributes to the improvement of the lens position accuracy. That is, the fourth group frame 14 and the fourth group cam ring 29 both engage the follower projection 14b projecting in the radial direction and the convex cam 29b, and do not have a grooved cam (cam groove). . Such a convex cam is less likely to cause deformation of an annular body such as a cam ring as compared with the case of forming a grooved cam, and is advantageous in terms of dimensional accuracy and strength of a molded product. Further, since the follower projection 14b and the convex cam 29b have a convex shape that can be easily removed from the mold at the time of molding, the follower projection 14b and the convex cam 29b can be integrally formed with the fourth group frame 14, the fourth group cam ring 29. This contributes to a reduction in manufacturing cost as compared with a conventional structure in which a roller that fits in is formed separately from the lens holding ring.

Further, the convex cam 29b does not require a draft such as a grooved cam (cam groove) at the time of molding.
It is easy to prevent backlash and gaps at the engagement portion with the follower projection 14b, and it is easy to correct parts. Specifically, the convex cam 29b is in the form of a long rib projecting in the inner diameter direction of the cam ring 29 for the fourth group, and its cross-sectional shape is substantially rectangular, and the cam surfaces (guide surfaces) on both sides have a lens barrel radius. It is an upright wall (vertical surface) substantially parallel to the direction. On the other hand, each of the pair of follower projections 14b sandwiching the long rib-shaped convex cam 29b has a cylindrical shape protruding in the outer diameter direction of the fourth group frame 14, and its axial direction is on both sides of the convex cam 29b. It is parallel to the guide surface. In other words, both side surfaces of the convex cam 29b and the cylindrical outer peripheral surface of each of the follower projections 14b are engaged in a linear region facing in the lens barrel radial direction, and are in a plane direction orthogonal to the axis of the follower projection 14b ( That is, backlash and displacement in the direction perpendicular to the lens barrel radial direction) are unlikely to occur.
The lens unit L4 can be guided accurately. Further, since a gap is hardly generated between the follower protrusion 14b and the convex cam 29b, there is little possibility that harmful light leaks from between the two.

As described above, according to the zoom lens barrel of the present embodiment, the third group frame 13 and the fourth group frame 1 related to the support and relative movement of the third lens unit L3 and the fourth lens unit L4.
Since the fourth and fourth group cam rings 29 do not have a penetrating portion in the radial direction, the positional accuracy of the third lens unit L3 and the fourth lens unit L4, which are excellent in dimensional accuracy and strength, and have high fall sensitivity, etc. Can be kept high. Further, since there is no penetrating portion around the cam mechanism and the straight guide mechanism, the passage of harmful light and foreign matter can be effectively prevented. That is, it is possible to obtain sufficient lens position accuracy and optical performance while suppressing costs as a molded product of these members.

Further, the components of the cam mechanism and the linear guide mechanism (follower projection 14b, convex cam 29b, linear guide projection 1)
3a) are the annular members (third group frame 13, fourth group frame 14, 4
Since it is easy to mold integrally with the group cam ring 29), these can be integrally molded with the annular member to reduce the manufacturing cost.

However, the present invention is not limited to the illustrated embodiment. For example, in the cam mechanism of the embodiment, the long rib-shaped cam projection (convex cam 29b) is provided with a rotating ring (4).
A follower projection (follower projection 14b) provided on the group cam ring 29) side and in sliding contact with the cam projection is provided on the lens holding ring (fourth group frame 14) side, but is longer on the lens holding ring side. It is also possible to provide a cam projection and provide a follower projection that slides on the cam projection on the rotating ring side. In short,
In a structure in which the lens retaining ring is moved in the direction of the optical axis by the rotation of the rotating ring, it is sufficient to prevent the penetration portions from being formed with each other.

In the embodiment, the pair of follower projections 14b sandwich the long rib-shaped convex cam 29b. However, only one follower projection is provided so that the follower projection always engages with the convex cam. May be energized by some means.

[0041]

As described above, according to the present invention, in a lens barrel having at least two lens groups which are relatively moved, it is possible to increase the positional accuracy and optical performance of the lens groups while suppressing the manufacturing cost. Can be done.

[Brief description of the drawings]

FIG. 1 is an upper half sectional view showing a zoom lens barrel according to an embodiment of the present invention, showing a zooming state to a telephoto end.

FIG. 2 is an upper half sectional view showing a zooming state to the wide end.

FIG. 3 is an upper half sectional view in which elements of a focus drive system are extracted and drawn from FIG. 2;

FIG. 4 is a front view of a single focus gear.

FIG. 5 is a side view of FIG.

FIG. 6 is a perspective view of a single focus lever.

FIG. 7 is an exploded exploded view showing a relationship among a first group frame, a second group moving frame, a cam ring, and an inner fixed cylinder.

FIG. 8 is a single-part view as viewed from the optical axis direction of the cam ring.

FIG. 9 is an exploded exploded view showing a relationship between a cam ring, an inner fixed cylinder, and a third group moving frame.

FIG. 10 is an exploded exploded view showing a relationship between a third group frame, a fourth group frame, and a cam ring for the fourth group.

FIG. 11 is a rear view showing the relationship between the third group frame, the fourth group frame, and the cam ring for the fourth group.

FIG. 12 is a diagram conceptually illustrating a relationship between power transmission paths and guides between constituent members of the zoom lens barrel according to the embodiment.

[Explanation of symbols]

 11 First group frame 11a Lead recess 11b Straight guide recess 12 Second group frame 12a Rotation transmitting arm 12b Lead groove (or cam groove) 13 Third group frame (first lens holding ring) 13a Straight guide protrusion 13b Circumferential direction Groove 13c Projection inlet 14 Fourth group frame (second lens holding ring) 14a Straight guide groove 14b Follower projection 15 Mount ring 16 Outer fixed cylinder 16a Inner flange 16b Retaining projection 17 Inner fixed cylinder 17a Through hole 17b Lead projection 17c Straight running guide recess 17d Escape groove 17f Through guide hole 18 Focus operating ring (MF operating ring) 19 Zoom operating ring 20 Coupler gear 20a Gear part 21 Focus gear 21a Sector gear 21b Introducing concave 21c Arc groove 21d Focus lever insertion groove 22 Focus lever 22a Radius Direction part 22b Outer diameter arm 22c Inner arm 22d Fixing screw 23 Cam ring 23a Lead follower 23b Lead protrusion 23c Rotation guide protrusion 23d Rotation transmission groove 23f Cam protrusion 24 Second group moving frame 24a Straight guide protrusion 24b Straight guide protrusion 24c Circular groove 24d Follower protrusion 24e Projection entrance 26 Zoom lever 27 Third group moving frame 27a Follower 27b Squeezing support annular portion 28 Fourth group cam drive lever 29 Fourth group cam ring (rotary ring) 29a Rotation guide projection 29b Convex cam (cam projection) 29c Rotation transmission Arm 40 Camera body 41 Mount 42 Coupler gear L1 First lens group L2 Second lens group L3 Third lens group (first lens group) L4 Fourth lens group (second lens group)

Claims (9)

[Claims] A first lens holding ring having a first lens group; a first lens holding ring having a first lens group; and a first lens holding ring rotatably supported by the first lens holding ring. A rotating ring driven to rotate; a second lens holding ring having a second lens group positioned between an inner surface of the rotating ring and an outer surface of the first lens holding ring; A bottomed rectilinear guide groove formed on one or the other of the outer surface and the inner surface of the second lens holding ring, and a rectilinear guide protrusion movably fitted in the rectilinear guide groove; A cam projection and a follower projection, which are formed on one and the other of the inner surface of the first lens holding ring and the outer surface of the second lens holding ring; and the first lens holding ring, the second lens holding ring, and the rotation. Each ring is a complete ring with no radial penetration A lens barrel, wherein the door. 2. The lens barrel according to claim 1, wherein the cam projection has a long rib shape having a substantially rectangular cross section, and the follower projection includes a pair of cylindrical projections sandwiching the long rib cam projection. Lens barrel. 3. The lens barrel according to claim 1, wherein the cam projection and the follower projection are engaged with each other in a linear engagement area that is oriented in a direction substantially parallel to the lens barrel radial direction. . 4. The lens barrel according to claim 1, wherein the first lens holding ring, the second lens holding ring, and the rotating ring are molded members made of synthetic resin. Lens barrel. 5. The lens barrel according to claim 1, wherein the cam projection is formed integrally with one of the rotating ring and the second lens holding ring, and the follower projection is formed. Is a lens barrel formed integrally with the other of the rotating ring and the second lens holding ring. 6. The lens barrel according to claim 1, wherein the straight guide projection is formed integrally with the first lens holding ring or the second lens holding ring. Lens barrel. 7. The lens barrel according to claim 1, wherein one of the first lens holding ring and the rotating ring has a bottom and is formed in a circumferential direction. A groove, and a rotation guide protrusion movably fitted in the bottomed circumferential groove. The first lens holding ring and the rotation ring are relatively rotated by fitting the rotation guide protrusion and the bottomed circumferential groove. A lens barrel that is combined as possible. 8. The lens barrel according to claim 1, wherein said lens barrel is a zoom lens barrel, and said first and second lens groups form part of a zoom lens. The lens barrel that makes up. 9. The lens barrel according to claim 8, further comprising: a zoom operation ring rotatable from outside; and a lens group which is rotated by the zoom operation ring and is different from the first and second lens groups. A rotation ring that moves in the axial direction and is different from the rotation ring; and a rotation guide projection provided on the rotation ring to engage with the cam ring and receive a rotation force. A lens barrel in which the rotating ring rotates in response to a moving operation, and the first and second lens groups are relatively moved;