JP2001215389A - Zoom lens barrel - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a zoom lens barrel capable of preventing the deterioration of the optical performance of a photographing optical system caused by external force exerted on a lens barrel. SOLUTION: This zoom lens barrel is equipped with plural lens groups changing the focal distance of the photographing optical system; and a cam ring having an inner surface cam groove for guiding at least one lens group out of plural lens groups on its inner peripheral surface and moving the lens group in an optical axis direction while following the cam groove in accordance with rotation. The cam ring is constituted of a lens supporting ring part where the inner surface cam groove is formed, and an edge outer peripheral ring part consisting of a different member from the lens supporting ring part and supported on the outer periphery of the edge part of the lens supporting ring part so as to rotate together therewith in a rotating direction. The edge outer peripheral ring part is supported to have a clearance in the optical axis direction with the lens supporting ring part, and an energizing spring energizing and moving the edge outer peripheral ring part in the optical axis direction and bent when the external force acts on the edge outer peripheral ring part from the outside of the lens barrel is inserted in the clearance part in the optical axis direction between the edge outer peripheral ring part and the lens supporting ring part.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

TECHNICAL FIELD The present invention relates to a zoom lens barrel.

[0002]

2. Description of the Related Art In a zoom lens barrel, there is known a mechanism in which a lens group guided in a straight line is guided along a predetermined locus in an optical axis direction by a rotational movement of a cam ring having a cam groove. . Conventionally, the cam ring itself often constitutes an external member of the lens barrel, or the cam ring directly supports the external tube of the lens barrel. That is, the cam ring is easily affected by external force, but this conventional cam ring has no particular problem in a silver halide film camera.

However, in a digital camera, since an image is formed on a CCD which is much smaller than the screen size of a silver halide film camera, the accuracy required of a lens is, for example, 1%.
An order of magnitude higher. For example, if the angle of view is the same, the smaller the image size, the shorter the focal length of the lens, and the smaller the lens, the lens frame and the like. Then, the influence of the same error, for example, an error of 10 μm on the lens system is larger in the digital camera. That is, an error that does not cause a problem in optical performance in a silver halide film camera becomes a problem in a digital camera.

[0004] From this point of view, the conventional cam ring arranged at a position susceptible to an external force is likely to be displaced in the direction of the optical axis, eccentric, or tilted with respect to the optical axis due to the external force. When such an error occurs in the cam ring, the lens group engaged with the cam groove of the cam ring is also affected, and as a result, the optical performance deteriorates.

[0005]

SUMMARY OF THE INVENTION The present invention has been made in consideration of the above problems, and has as its object to provide a zoom lens barrel in which external force applied to the barrel hardly affects the optical performance of a photographing optical system.

[0006]

SUMMARY OF THE INVENTION The present invention has a plurality of lens groups for changing the focal length of a photographing optical system; and an inner cam groove for guiding at least one lens group among the plurality of lens groups on an inner peripheral surface; A cam ring for moving the lens group in the optical axis direction in accordance with the rotation of the lens group in accordance with the rotation of the inner surface of the lens group. The lens support ring portion is formed of a separate member, and is constituted by a distal end outer peripheral ring portion supported so as to rotate together in the rotational direction on the outer periphery of the distal end portion of the lens support ring portion,
The front end outer peripheral ring portion is supported with a clearance in the optical axis direction with respect to the lens support ring portion. It is characterized in that an urging spring which is moved and urged and which bends when an external force is applied from outside the lens barrel to the outer peripheral ring portion of the distal end is inserted. According to this zoom lens barrel, since the external force transmitted to the distal end outer ring formed of a member separate from the lens support ring is buffered by the biasing spring, the lens group supported in the lens support ring is subjected to the external force. And the optical performance can be prevented from deteriorating. The biasing spring is formed of, for example, a compression coil spring.

[0007] As a configuration for supporting the outer peripheral ring portion of the tip,
A stopper projection provided on the outer peripheral surface of the lens support ring portion of the cam ring so as to protrude outward in the radial direction; inside the lens support ring portion, it is rotatable relative to the lens support ring portion and is not movable relative to the optical axis direction. A linear guide ring that guides the lens group in the optical axis direction, and a flange ring fixed to the front end of the linear guide ring. It is preferable to be configured so as to be movably supported by a certain distance between the flange and the flange ring, and to be urged in a direction in which the urging spring inserted between the stopper projection and the flange ring contacts the flange ring. In this configuration,
The outer peripheral portion of the distal end has a rectilinear guide that slidably engages with the stopper protrusion in the optical axis direction, and it is preferable that an urging spring is disposed along the rectilinear guide.

Further, as a configuration outside the outer peripheral ring portion of the tip,
An external cylinder located outside the cam ring and guided straight in the optical axis direction; a guide pin protruding radially inward from the external cylinder; and formed on the outer peripheral surface of the outer peripheral ring portion at the tip of the cam ring. Further, it is preferable to have an advancing / retracting guide groove which engages with the guide pin and which advances / retreats the external cylinder in the optical axis direction by rotation of the cam ring. Even if an external force is applied to the outer peripheral ring portion of the distal end from the external cylinder via the guide pin and the reciprocating guide groove, the external force hardly affects the lens group according to the configuration of the present invention, so that the deterioration of the optical performance can be prevented. . As described above, when the distal end outer peripheral ring portion is supported so as to be movable by a fixed distance between the stopper protrusion and the flange ring in the optical axis direction, the flange ring has a linear guide protrusion protruding radially outward. It is preferable that the straight guide projection is configured to be fitted in a straight guide groove formed in the inner peripheral surface of the external cylinder in parallel with the optical axis to guide the external cylinder straight.

In the above-described zoom lens barrel, the lens supporting ring portion further projects radially outward on the outer peripheral surface near the distal end thereof, and has a shorter length in the optical axis direction than the distal outer peripheral ring portion. It is preferable that the inner peripheral surface of the lens unit has a supporting step on which the inner peripheral surface is placed, and that the outer peripheral surface of the lens supporting ring and the inner peripheral surface of the outer peripheral ring of the distal end be separated from the supporting step. At this time, a region of the advance / retreat guide groove formed on the outer peripheral surface of the distal end outer peripheral ring portion, which is used in the use state of the zoom lens barrel,
It is preferable that the contact area between the inner peripheral surface of the outer peripheral ring portion and the supporting step portion is different from each other in the optical axis direction.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS In the present embodiment, the present invention is applied to a zoom lens for a digital camera. First, the overall structure will be described, and then the features of the present invention will be described.

[0011]

Description of the Entire Lens Barrel of the Present Embodiment The configuration of the zoom lens barrel of the present embodiment will be described with reference to FIGS. In the following description, an uppercase letter (F) in parentheses after a number following a member name indicates that the member is fixed, and (L) indicates that the member moves straight in the optical axis direction. (RL) indicates that it moves in the optical axis direction while rotating.

The lens arrangement according to this embodiment includes a first lens unit L1 (L) and a second lens unit L2 in order from the object side.
(L), and a third lens unit L3 (L). Zooming is performed by moving the first lens unit L1 and the second lens unit L2 along the optical axis along a predetermined locus while changing the distance between them. . The third lens unit L3 is a first lens unit L
1. It functions as a focusing lens regardless of the position of the second lens unit L2, and is a so-called rear focusing zoom lens system.

A fixed ring 11 (F) is fixed to the housing 10 (F) fixed to the camera body (or constituting a part of the camera body). Fixed ring 11
Has a fine male screw 11a on its outer peripheral surface, and on its inner peripheral surface,
A female helicoid 11b and a straight guide groove 1 formed by cutting out a part of the female helicoid 11b and extending in a direction parallel to the optical axis.
1c. Three straight guide grooves 11c are formed at 120 ° intervals.

In the housing 10, as shown in FIG.
A CCD insertion window 10a, a filter fixing section 10b, and a focus lens group moving guide 10c are provided. CCD
A CCD 12a fixed to the substrate 12 is inserted into the insertion window 10a.
A filter 10d such as a low-pass filter is fixed to the filter fixing unit 10b. The focus lens group moving guide 10c has a third movable
The lens group L3 is supported, and the moving position of the third lens group L3 is determined by the rotation direction and the rotation angle (amount) of the feed screw 10e. The rotation angle of the feed screw 10e is pulse-managed by a pulse motor (encoder).

A rotating ring 13 (RL) is provided outside the fixed ring 11.
Is located on the inner peripheral surface of the rotating ring 13.
3a is screwed into the male screw 11a of the fixed ring 11. The rotating ring 13 has a gear 13b (FIG. 1) on the outer peripheral surface, and is driven to rotate via a pinion (not shown) that meshes with the gear 13b. When the rotary ring 13 is rotationally driven, it moves in the optical axis direction while rotating according to the female screw 13a.
On the inner surface of the tip of the rotating ring 13, at intervals of 120 °,
The rotation transmission protrusion 13c is formed. In addition, rotating ring 1
3 has a code plate 14 (RL) facing in the circumferential direction.
(FIG. 1) is fixed, and a brush 15 (F) (the same) that slides on the code plate 14 is fixed to the housing 10. The cord plate 14 and the brush 15 are
a (female screw 13a), the code plate 14 (rotary ring 13) is kept in contact with each other irrespective of the movement position of the code plate 14 (rotary ring 13), and detects the rotational position of the rotary ring 13 as digital information and / or analog information. It is provided as follows. The female screw 13 a of the rotating ring 13 is a means for rotatably supporting the rotating ring 13 on the fixed ring 11.
May be supported on the stationary ring 11 such that the movement in the optical axis direction is restricted and only the rotation is possible.

A linear guide ring 16 is provided inside the fixed ring 11.
(L) and a cam ring 17 (R) fitted on the outer peripheral surface of the straight guide ring 16 so as to restrict movement in the optical axis direction and enable relative rotation.
L) and a second cam ring 18 (RL) which rotates together in the rotation direction and is fitted to the outer periphery of the distal end of the cam ring 17 so as to be relatively movable in the optical axis direction. That is,
The rectilinear guide ring 16 has an outer flange 16a at its rear end and a rectilinear guide ring (flange ring) 1 at its front end.
9 (L) is fixed via a retainer ring 20 (L). The cam ring 17 is sandwiched between the outer flange 16a and the rectilinear guide ring 19, and is supported so that relative rotation with respect to the rectilinear guide ring 16 is free to move together in the optical axis direction. I have.

The second cam ring 1 fitted to the tip of the cam ring 17
8 is a rectilinear guide portion 1 slidably engaged with a stopper projection 17a formed on the outer peripheral surface of the cam ring 17 at intervals of 120 °.
8a, it is supported so as not to rotate relative to the cam ring 17 but to allow only relative movement in the optical axis direction. A compression spring 21 for urging the second cam ring 18 to move forward is provided near the stopper projection 17a and the linear guide portion 18a.
Is inserted, and the second cam ring 18 is always in contact with the straight guide ring 19. The second cam ring 18 can retreat while flexing the compression spring 21 by the clearance in the optical axis direction between the stopper projection 17a and the linear guide portion 18a. Further, it is possible to incline only by the clearance in the radial direction.

On the outer peripheral surface of the cam ring 17, a male helicoid 17b screwed with the female helicoid 11b of the fixed ring 11 is formed. A part of the male helicoid 17b is cut off to transmit the rotation of the rotary ring 13. A rotation transmission groove 17c is formed parallel to the optical axis, in which the protrusion 13c is slidably fitted. On the other hand, on the outer flange 16a of the rectilinear guide ring 16, rectilinear guide protrusions 16b projecting radially outward and fitting into the rectilinear guide grooves 11c of the fixed ring 11 are formed at 120 ° intervals.
The rectilinear guide ring 16 is also provided with rectilinear guide through grooves 16c, which penetrate in a direction parallel to the optical axis at intervals of 120 ° at the same circumferential position as the rectilinear guide protrusion 16b.

As shown in FIGS. 4 and 5, the rectilinear guide through groove 16c is opened at the rear end face of the rectilinear guide ring 16, and the outer diameter side thereof has an outer flange 16a and a rectilinear guide protrusion 16b.
Is blocked by A cam follower insertion groove 16h is formed on the outer flange 16a on the inner diameter side at the same circumferential position as the rectilinear guide projection 16b.

When the combined body of the straight guide ring 16, the cam ring 17 and the second cam ring 18 is engaged with the fixed ring 11 and the rotary ring 13, the guide portion 1 is inserted into each straight guide groove 11c of the fixed ring 11.
1d, the respective linear guide projections 16b of the linear guide ring 16 are fitted, and the respective rotational transmission grooves 13c of the cam ring 17 are fitted with the respective rotation transmission projections 13c of the rotary ring 13 from the introduction portion 17d.
In this state, the female helicoid 11b of the fixed ring 11 and the cam ring 1
And 7 male helicoids 17b. The male screw 11a of the fixed ring 11 and the female screw 13a of the rotating ring 13 are screwed together.

When the rotating ring 13 is driven to rotate through the gear 13b in the state where the assembly is completed as shown in FIG. 2, the rotating ring 13 rotates in the screwing relationship between the female screw 13a and the male screw 11a in the optical axis direction. Reciprocate and simultaneously the cam ring 17
The rotation is transmitted to the second cam ring 18 mounted on the outer diameter side of the cam ring 17 in a sliding relationship between the rotation transmitting projection 13c and the rotation transmitting groove 17c, and the screw between the male helicoid 17b and the female helicoid 11b is screwed. Movement in the direction of the optical axis is given in a joint relationship. At this time, the rectilinear guide ring 16 advances and retreats in the optical axis direction without rotating due to the sliding relationship between the rectilinear guide protrusion 16b and the rectilinear guide groove 11c, and rotates relative to the rectilinear guide ring 16.
7. The second cam ring 18 moves together with the straight guide ring 16 in the optical axis direction.

On the inner peripheral surface of the cam ring 17, there are formed a first group cam groove 17C1 and a second group cam groove 17C2 whose development shapes are shown in FIG. The cam groove 17C1 for the first group and the cam groove 17C2 for the second group are formed by forming three identical shapes at intervals of 120 °.
It has a tele end position and a wide end position. The rotation angle of the cam ring 17 from the storage position to the wide end position is A.

The first lens frame 22 (L) holding the first lens group L1 and the second lens frame 23 (L) holding the second lens group L2 are formed by the first group cam groove 17C1 and the second group cam groove 17C1. It is guided by the cam groove 17C2 for use and the rectilinear guide through groove 16c of the rectilinear guide ring 16, and moves linearly in the optical axis direction. The first lens frame 22 is provided with three elastic tongues 22b projecting rearward from the cylindrical portion 22a at intervals of 120 °.
A square projection 22c that fits slidably on c is formed, and a follower pin 22d that projects in the radial direction is implanted and fixed on the square projection 22c. The angular projection 22c is formed in the straight guide groove 16
It is sufficient that the contact portion with c is a projection that is a parallel plane. First
The lens barrel 22e to which the lens group L1 is fixed is
The first lens group L1 in the first lens frame 22 can be adjusted in the optical axis direction by adjusting the screwing position. Lens barrel 22e
Has a wave washer 22h sandwiched between it and the flange 22g of the first lens frame 22.
Due to the elasticity of 2h, the lens barrel 22e (the first lens unit L
The play in the optical axis direction of 1) is eliminated.

The second lens frame 23 is provided with three elastic tongues 23b projecting forward from the annular portion 23a at intervals of 120 °. Is formed, and a follower pin 23d projecting in the radial direction is implanted and fixed on the angular projection 23c. This angular projection 23c
The follower pin 23d is similar to the angular projection 22c of the first lens frame 22 and the follower pin 22d, except that the direction of the elastic tongue piece 23b is opposite to the direction of the elastic tongue piece 22b. The lens barrel 23e to which the second lens unit L2 is fixed is fixed to a flange 23 of the second lens frame 23 via a fixing screw 23f.
g. A shutter block 24 is fixed to the flange 23g of the second lens frame 23.
When the shutter is released, the shutter block 24
It has a function of blocking a light beam given to D12a.

The above-described first lens frame 22 and second lens frame 2
3 is guided linearly by fitting each of the angular projections 22c and the angular projections 23c into the same corresponding linear guide through groove 16c of the linear guide ring 16. And follower pin 2
2d and the follower pin 23d protrude radially from the rectilinear guide through groove 16c of the rectilinear guide ring 16,
The cam ring 17 is fitted to the cam groove 17C1 for the first group and the cam groove 17C2 for the second group of the cam ring 17 which are relatively slidably fitted on the outer periphery of the cam ring 17. The first lens frame 22 and the second lens frame 2
3 is fitted into the linear guide ring 16 and the cam ring 17, the angular projections 22 c and 23
c into the straight guide through groove 16c and follower pin 22d
And 23d are passed through the cam follower insertion groove 16h, and then fitted into the cam grooves 17C1 and 17C2. In FIG. 3, the hatched areas in the contours of the cam grooves 17C1 and 17C2 are used during assembly (follower pin 2).
2d and 23d pass) and are not used in use.

When the rotating ring 13 is rotated by the above-described guide structure, the cam ring 17 and the second cam ring 18 rotate, and the linear guide ring 16 does not rotate. 17. The combined body of the second cam ring 18 advances and retreats in the optical axis direction. As a result, the first lens frame 22 (first lens group L1) and the second lens frame 23 (second lens group L2)
However, in accordance with the cam profiles of the first group cam groove 17C1 and the second group cam groove 17C2, zooming is performed by moving straight in the optical axis direction while changing the air gap between each other.

Next, the connection structure of the straight guide ring 19 and the retainer ring 20 to the tip of the straight guide ring 16 will be described with reference to FIGS. The straight guide ring 16 has three bayonet claws 16d formed at its tip at 120 ° intervals so as to protrude in the radial direction, and the small-diameter insertion portion 16e is located between the bayonet claws 16d. I have. A small-diameter portion 16f having the same diameter as the small-diameter insertion portion 16e is formed on the back surface of the bayonet claw 16d, and is positioned on the back surface of the bayonet claw 16d, and the small-diameter portion 16f is cut out in a direction parallel to the axis. A recess 16g is formed.

On the other hand, the linear guide ring 19 has, on its inner peripheral surface, a rotation restricting convex portion 19a which can be inserted between the small-diameter insertion portion 16e and the bayonet claw 16d and can rotate relative to the small-diameter portion 16f after insertion. Are formed at intervals of 120 °. In addition, on the outer peripheral surface of the straight guide ring 19, straight guide projections 19b defining the circumferential position with respect to the rotation restricting projection 19a are formed at intervals of 120 °.

On the inner peripheral surface of the retainer ring 20,
The bayonet claw 1 is inserted from the small-diameter insertion portion 16 e of the straight guide ring 16.
Fixed claws 20a which can be inserted between 6d and are rotatable relative to the small diameter portion 16f after insertion are formed at 120 ° intervals. Further, on the front end surface, a crimping groove 20b for rotating operation is formed.

When the straight guide ring 19 is fixed to the distal end of the straight guide ring 16, the straight guide ring 19 is fitted with the rotation restricting projection 19a into the small-diameter insertion portion 16e.
f and rotate the rotation restricting projection 19a to the bayonet claw 1
6d and fitted into the rotation restricting recess 16g. By this fitting, the circumferential position of the straight guide ring 19 with respect to the straight guide ring 16 is determined. Next, the retainer ring 20 is fitted with its fixed claw 20a into the small-diameter insertion portion 16e and rotated on the small-diameter portion 16f, and presses the rotation restricting convex portion 19a against the rotation restricting concave portion 16g to move the linear guide ring 19 in the axial direction. Suppress. In this locked state, the fixed claw 20
a enters between the bayonet claw 16d and the rotation restricting protrusion 19a, and the fixed claw 20a and the bayonet claw 16d prevent the straight guide ring 19 from coming off. Irregularities are provided between the rectilinear guide ring 16 and the retainer ring 20 to prevent rotation of the retainer ring 20 (giving a click feeling) in the locked state. FIG. 6 shows only the unevenness 16j on the straight guide ring 16 side.

The rectilinear guide projection 19b of the rectilinear guide ring 19 fixed to the end of the rectilinear guide ring 16
It is at a specific position (angular relationship) that is predetermined with respect to the straight guide projection 16b of the straight guide ring 16. This straight guide projection 1
9b is 12 dia. On the inner peripheral surface of the appearance cylinder (hood cylinder) 25 (L).
Straight guide grooves 2 formed at 0 ° intervals and parallel to the optical axis
5a, and guides only the movement in the optical axis direction without rotating the appearance tube 25. The appearance cylinder 25 has 12
Three guide pins 25b are planted at 0 ° intervals,
This guide pin 25b is attached to the outer peripheral surface of the second cam ring 18 by one.
It is fitted in the same-shaped advance / retreat guide groove 18b formed at intervals of 20 °.

As shown in FIGS. 8 and 9, the reciprocating guide groove 18b is provided at an assembling position where the guide pin 25b is inserted at the time of assembling, and at a storing position corresponding to the storing position of the cam ring 17, the tele end position, and the wide end position. The outer cylinder 25 is moved in the optical axis direction in accordance with the rotation position of the second cam ring 18 which has a tele end position and a wide end position and rotates together with the cam ring 17. That is, the appearance cylinder 25 is advanced with respect to the second cam ring 18 (the first lens unit L1) at the tele end position where the angle of view is narrow, and is retracted at the wide end position where the angle of view is large, thereby serving as a lens hood. Is given. FIG. 10 shows the position of the appearance tube 25 at the wide end position, and FIG. 11 shows the position of the appearance tube 25 at the tele end position.

As described above, between the second cam ring 18 for guiding the external cylinder 25 and the cam ring 17 for guiding the first lens unit L1 and the second lens unit L2, the second cam ring 18 is provided forward. When an external force in the pushing direction is applied to the external appearance cylinder 25 during use, at least a part of the external force can be absorbed by the compression spring 21. That is, the external force is applied to the compression spring 21.
Is compressed and transmitted from the second cam ring 18 to the cam ring 17, so that a large external force is not applied to the cam ring 17. Therefore, the influence on the positional accuracy of the first lens unit L1 and the second lens unit L2 can be reduced. For more detailed movement and operation of the appearance tube 25, see the appearance tube 22
After explaining the barrier block 27 fixed to the tip of
This will be further described with reference to FIG. Reference numeral 29 in FIG.
(F) is a cover cylinder integral with the camera body side, in which the external appearance cylinder 25 advances and retreats inside.

A barrier drive ring 26 is rotatably supported on the outer cylinder 25 at the inner diameter at the front end thereof. The barrier drive ring 26 is rotated by its rotational motion to form a barrier block 27.
To open and close the barrier. Barrier block 27
As shown in FIG. 1 and FIGS. 13 to 15, a decorative plate 27b having a photographing opening 27a, two pairs of barriers 27c and 27d supported by the decorative plate 27b to open and close the photographing opening 27a, It has a pair of torsion springs 27e for urging 27c and 27d in the direction to close the photographing opening 27a, and a barrier presser plate 27f for sandwiching and holding these elements between a decorative plate 27b and assembling them as separate units in advance. Can be The barriers 27c and 27d are rotatable coaxially with a common shaft 27g provided on the decorative board 27b, and the inner barrier 27d is rotated in the closing direction by a torsion spring 27e hooked on a spring hook 27n of the decorative board 27b. Being energized. The barrier 27d is formed with a projection 27h for opening and closing the barrier 27d against the force of the torsion spring 27e.
When the barrier 27d moves in the opening direction, an interlocking projection 27i is formed which engages with the edge of the barrier 27d and moves the barrier 27c together with the barrier 27d in the opening direction. When the barrier 27d moves in the closing direction, the barrier 27c and the barrier 27d are joined to the barrier 27c and 27d together.
In the closing direction are formed with interlocking projections 27j and 27k (FIG. 15). The opening / closing projection 27 is provided on the barrier holding plate 27f.
An exposed hole 27m is formed to project h toward the barrier drive ring 26 side.

The barrier drive ring 26 is shown in FIGS.
As shown in FIG. 5, a spring hook projection 26b formed on the barrier drive ring 26 itself and a spring hook projection 2
5c, which is urged to rotate in the barrier opening direction by a tension spring 28, which is stronger than the torsion spring 27e, and is engaged with the barrier drive ring 26 by the opening and closing projection 27h of the barrier 27d. An opening / closing dowel 26c for opening 27c and 27d is formed. When the barrier drive ring 26 is located at the rotation end due to the force of the tension spring 28, the opening and closing dowel 26c presses the opening and closing protrusion 27h, and opens the barrier 27d against the force of the torsion spring 27e, and the interlocking protrusion 27i. 27c is also opened via (FIG. 15).

On the other hand, as shown in FIG. 16, the barrier drive ring 26 has a rotation transmission projection 26a projecting toward the second cam ring 18 at a part in the circumferential direction. Are the rotation imparting concave portions 1 formed on the second cam ring 18.
8c (see also FIGS. 8 and 9). Barrier drive ring 2
6 is rotatably supported at a fixed position in the optical axis direction by the external appearance cylinder 25. Therefore, when the external appearance cylinder 25 advances and retreats in the optical axis direction according to the advance / retreat guide groove 18b of the second cam ring 18, FIGS. As can be seen in FIG. 9, it comes into contact with and separates from the rotating second cam ring 18. Rotation transmitting protrusion 26a and rotation imparting concave portion 1
8c does not contact (engage) with each other in the photographing position (between the tele end position and the wide end position) as shown in FIG. 8, and moves from the tele end position to the storage position as shown in FIG. The barrier drive ring 2 is engaged with each other and
6 is formed so that a forced rotation force is applied to the same. When the barrier drive ring 26 rotates to the moving end against the tension spring 28, the opening and closing dowel 26c of the barrier drive ring 26 is moved to the barrier 27.
d is separated from the opening / closing projection 27h, and as a result, the barrier 27d is opened by the force of the torsion spring 27e.
The barrier 27c is closed via k and 27j and the shooting aperture 27 is closed.
a closes (FIG. 14). Conversely, during the transition from the storage position to the tele end position, the rotation transmitting projection 26a gradually separates from the rotation providing concave portion 18c, and the barrier driving ring 26 is rotated in the barrier opening direction by the tension spring 28, so that the opening and closing dowel is opened. 26
c pushes the opening / closing projection 27h, and the barriers 27c and 27d are opened via the interlocking projection 27i. That is, the barrier 27c, 2
The opening and closing of 7d is performed by the rotation of the barrier drive ring 26. The rotation transmission projection 26a formed on the barrier drive ring 26 is only one, whereas three rotation imparting recesses 18c formed on the second cam ring 18 are formed at 120 ° intervals. Can be selected.

As described above, the external cylinder 25 guided to move straight in the optical axis direction moves forward and backward by the rotation of the second cam ring 18. On the other hand, the first lens unit L1 and the second lens unit L2 are moved back and forth by the rotation of the cam ring 17. FIG. 12 shows the storage position, the image plane of the CCD 12a, (the principal point positions of the first lens unit L1 and the second lens unit L2) from the tele end position to the wide end position, and the barrier block 27 ( 3 shows a change in the position of the photographing opening 27a) of the decorative plate 27b at the front end of FIG. Cam ring 1
7, the cam grooves 17C1 and 17C2, and the second cam ring 18
Is set so that such a movement locus can be obtained. The photographing opening 27a has a substantially rectangular shape in front, and has an angle of view in a short side direction, an angle of view in a long side direction,
The angle of view in the diagonal direction increases in order. 10 and 11, the light beam S incident from the short side direction of the photographing aperture 27a, the light beam M incident from the long side direction, and the light beam L incident from the diagonal direction.
Is shown.

A light-shielding tube 26d extending from the barrier drive ring 26 to the outer periphery of the distal end of the first lens frame 22 is fixed (adhered) to the inner diameter of the barrier drive ring 26. The light-shielding tube 26d has a rotationally symmetrical shape about the optical axis, and its light-shielding function does not change even if the barrier drive ring 26 reciprocates and rotates.

The components constituting the zoom lens barrel described above are all molded products of a synthetic resin material except for the springs, feed screws 10e, fixing screws 23f, follower pins 22d and 23d, shutter block 24 and guide pins 25b. Consists of

In the above embodiment, the third lens unit L3 is a focus lens unit, but another lens unit, for example, the first lens unit L1 or the second lens unit L2 may be a focus lens unit. When the second lens unit L2 is a focus lens unit, the shutter block 24
Can be provided with a focusing function, and such shutter blocks are well known.

[0041]

DESCRIPTION OF THE FEATURES OF THE INVENTION As described above, in the zoom lens barrel of the present embodiment, the cam ring has a cam groove 17C on its inner surface.
A cam ring 17 (lens support ring) which has the first lens unit L1 and the second lens unit L2 for moving and guiding the first lens unit L1 and the second lens unit L2.
And a second cam ring 18 made of a member separate from the cam ring 17 and fitted around the outer periphery of the tip of the cam ring 17 so as to rotate together.
(Tip outer peripheral ring portion). FIG. 19 shows the cam ring 17 and the second cam ring 18 in a developed state. As shown in the figure, a male helicoid 17b is formed on the outer peripheral surface of the cam ring 17 from the rear end toward the front of the optical axis with a constant width, and the front end of the male helicoid 17b is formed in front of the area where the male helicoid 17b is formed. The part is a thin annular body 1 in which no helicoid is formed.
7e. The second cam ring 18 is a thin ring 1
7e is mounted on the outer peripheral surface.

The length of the second cam ring 18 in the optical axis direction corresponds to the length of the thin ring 17e in the optical axis direction.
When the cam ring 17 is placed on the cam ring 17, the movement of the cam ring 17 to the front of the optical axis is restricted by the straight guide ring 19 (flange ring) fixed to the front end of the straight guide ring 16. On the other hand, toward the rear of the optical axis, the second cam ring 18 is moved by the clearance in the optical axis direction between the stopper projection 17a and the linear guide portion 18a.
Can retreat.

The thin ring 17e of the cam ring 17 has an annular supporting step 17f on the outer peripheral surface near the tip. The supporting step 17f is formed so as to slightly project radially outward from the outer peripheral surface of the thin ring body 17e, and is shorter in the optical axis direction than the length of the second cam ring 18 in the optical axis direction. As shown in FIG. 2, the inner peripheral surface of the second cam ring 18 abuts on the support step 17 f in a part of the region near the distal end, and the outer peripheral surface of the thin annular member 17 e is located behind the contact region. The inner peripheral surfaces of the two cam rings 18 are separated without contacting each other.

The second cam ring 18 has a function of moving the external cylinder 25 in the optical axis direction when rotated via a guide pin 25b fitted in an advance / retreat guide groove 18b formed on the outer peripheral surface thereof. In other words, it functions as an external cylinder support member that supports the external cylinder 25. Therefore, when an external force is applied to the external cylinder 25, the external force is also applied to the second cam ring 18 from the fitting portion between the guide pin 25b and the reciprocating guide groove 18b. Here, the second cam ring 18 is a cam ring 1 supporting the first lens unit L1 and the second lens unit L2.
Since the external force does not directly act on the cam ring 17, the external force applied from the outside of the lens barrel seriously affects the first lens unit L 1 and the second lens unit L 2. Can be prevented.

For example, as shown in FIG. 2, when the external cylinder 25 is extended from the camera body and a force is applied to the external cylinder 25 to push the external cylinder 25 rearward (inward of the camera body), the guide pins 25b and the reciprocating guide grooves are provided. A force in the same direction is applied to the second cam ring 18 via 18b. Here, the second cam ring 18 is a separate member from the cam ring 17,
a and the rectilinear guide portion 18a can be retracted by the clearance in the optical axis direction.
In accordance with the force applied to 5, the cam ring 17 moves backward without moving. As a result, the external force is not directly applied to the cam ring 17 supporting the first lens unit L1 and the second lens unit L2, and it is possible to prevent an error in the optical axis direction of the photographing optical system.

In this zoom lens barrel, in particular, a compression spring 21 (compression coil spring) is provided between the linear guide portion 18a of the second cam ring 18 and the stopper projection 17a of the cam ring 17. Since the compression spring 21 normally urges the second cam ring 18 in a direction in which it comes into contact with the linear guide ring 19, and holds the second cam ring 18 against the cam ring 17 without play, The rattle of the front external cylinder 25 and the barrier block 27 supported via the second cam ring 18 is suppressed. If there is play in the lens barrel external members such as the external tube 25 and the barrier block 27, it is not desirable to use the camera even if it does not affect the optical performance of the photographing optical system. Even if the cam ring 17 and the second cam ring 18 are divided with a clearance that can be moved by a fixed distance in the optical axis direction, the usability of the camera can be maintained. Then, when an external force pushing the outer cylinder 25 toward the rear of the optical axis is applied, the second cam ring 18 moves backward while bending the compression spring 21. At this time, the compression spring 21 functions as a buffer member that buffers external force transmitted from the external cylinder 25 to the second cam ring 18 between the cam ring 17 and the first lens group L <b> 1 inside the cam ring 17 and the first lens group L 1. This prevents an error in the photographing optical system due to the influence of external force on the second lens unit L2.

The inner peripheral surface of the second cam ring 18 and the cam ring 1
The outer peripheral surface of 7 (thin ring 17e) is not in contact with the rear of the supporting step 17f, and a slight gap is secured in the radial direction. Therefore, when an external force is applied to push the guide pin 25b inward in the radial direction via the external cylinder 25, the second cam ring 18 is displaced in the radial direction with the contact portion with the supporting step 17f as a fulcrum. (Tilt, deformation) are allowed. Due to the displacement of the second cam ring 18, it becomes difficult for the external force applied in the radial direction to reach the cam ring 17 supporting the lens groups L1 and L2, and the first lens group 1 and the second lens group L2
Falling and eccentricity can be prevented. As shown in FIG. 19, a supporting step 17f which is a contact area between the second cam ring 18 and the cam ring 17 is formed substantially at the front end of the cam ring 17, and the second cam ring 18 is formed into a thin ring member 17e. When mounted on the upper side, most of the advance / retreat cam groove 18b, at least the area where the guide pin 25b passes when the zoom lens barrel is used, is located behind the support step 17f in the optical axis direction. That is, when the zoom lens barrel is in use, the contact area between the cam ring 17 and the second cam ring 18 (support step 17f)
And the action area of the external force applied to the second cam ring 18 (the use area of the reciprocating cam groove 18b) does not overlap in the optical axis direction, so that the radial external force applied to the second cam ring 18
7 is less likely to be affected.

As is apparent from the above description, in the zoom lens barrel of the present embodiment, the cam ring for supporting the lens group and guiding the movement in the optical axis direction is provided with a lens support having an inner cam groove for supporting the lens group. The ring (cam ring 17) and the lens support ring are made of separate members, and are supported on the outer circumference of the tip of the lens support ring so as to rotate together in the rotational direction (the first ring). 2 cam ring 18), and furthermore, at the clearance portion in the optical axis direction between the lens support ring portion and the tip outer peripheral ring portion, the tip outer peripheral ring portion is always stably held.
When an external force is applied to the outer peripheral ring of the distal end, an urging spring that functions as a cushioning member is inserted between the lens and the ring support ring. Even if external force acts on the lens barrel, the optical performance of the photographic optical system is affected. Can not be. Since this biasing spring normally acts to remove play between the lens support ring and the outer peripheral ring at the tip, in a normal use state of the zoom lens barrel, the outer appearance of the barrel is loose. And a good feeling of use can be obtained.

[0049]

As described above, according to the present invention, it is possible to obtain a zoom lens barrel that does not easily affect the optical performance of the photographing optical system even when an external force is applied to the barrel.

[Brief description of the drawings]

FIG. 1 is an exploded perspective view showing the entire structure of a zoom lens barrel according to the present invention.

FIG. 2 is an upper half sectional view of the assembled state.

FIG. 3 is a development view of a cam groove of a cam ring.

FIG. 4 is an exploded perspective view showing a relationship among a first lens frame, a second lens frame, a straight guide ring, and a cam ring.

FIG. 5 is a rear view of a straight guide groove portion of the straight guide ring.

FIG. 6 is an enlarged exploded perspective view of a straight traveling guide ring, a straight traveling guide ring, and a retainer ring in an exploded state.

FIG. 7 is an enlarged exploded view of the same.

FIG. 8 is a development view showing a positional relationship between a second cam ring and a barrier drive ring in a shooting state (tele end position).

FIG. 9 is a development view showing a positional relationship in the housed state.

FIG. 10 is an upper half sectional view showing a positional relationship between an external appearance cylinder and a second cam ring (first lens group) in a wide-angle shooting state.

FIG. 11 is an upper half sectional view showing the positional relationship between the external cylinder and a second cam ring (first lens group) in a telephoto shooting state.

FIG. 12 is an upper half sectional view showing the positional relationship between the external cylinder and a second cam ring (first lens group) in a telephoto shooting state by a solid line, and showing the positional relationship in a wide shooting state by a chain line.

FIG. 13 is an exploded perspective view of the barrier block as viewed from the rear side.

FIG. 14 is a perspective view of the barrier block excluding the barrier press plate as viewed from the rear side in an assembled state.

FIG. 15 is a front view showing the barrier block in a barrier open / closed state.

FIG. 16 is an exploded perspective view showing a relationship between a rotation imparting concave portion of a second cam ring and a rotation transmitting projection of a barrier drive ring.

FIG. 17 is a front view of the barrier drive ring rotatably supported by the external cylinder at one rotation end (barrier closed position).

FIG. 18 is a front view of the barrier drive ring at the other rotation end (barrier open position).

FIG. 19 is an exploded view showing a cam ring and a second cam ring divided.

[Explanation of symbols]

 L1 First lens group L2 Second lens group L3 Third lens group 10 Housing 11 Fixed ring 11a Male screw 11b Female helicoid 11c Straight guide groove 12 Substrate 12a CCD 13 Rotating ring 13a Female screw 13b Gear 13c Rotating transmission protrusion 14 Code plate 15 Brush 16 Straight guide ring 16a Outer flange 16b Straight guide projection 16c Straight guide penetration groove 16d Bayonet claw 16e Small diameter insertion portion 16f Small diameter portion 16g Rotation restricting concave portion 16h Cam follower insertion groove 17 Cam ring (lens support ring) 17a Stopper protrusion 17b Male helicoid 17c Rotation transmitting groove 17d Introducing portion 17e Thin ring member 17f Support step 18 Second cam ring (tip outer peripheral ring portion) 18a Linear guide portion 18b Advance / retreat guide groove 18c Rotation providing concave portion 19 Linear guide ring 19a Rotation restricting convex portion 19b Advance guide projection 20 retainer ring 20a fixing claw 20b claw groove 21 compression spring 22 first lens frame 22a cylindrical portion 22b elastic tongue piece 22c square projection (parallel flat projection) 22d follower pin 22f screw 22g flange 22h wave washer 23 second lens frame 23a Annular portion 23b Elastic tongue 23c Square projection (parallel plane projection) 23d Follower pin 23e Lens cylinder 23f Fixing screw 23g Flange 24 Shutter block 25 External cylinder (hood cylinder) 25a Straight guide groove 25b Guide pin 25c Spring hook 26 Barrier drive ring 26a Rotation transmitting protrusion 26b Spring hooking protrusion 26c Opening and closing dowel 26d Light shielding cylinder 27 Barrier block 27a Photographing opening 27b Decorative plate 27c 27d Barrier 27e Torsion spring 27f Barrier holding plate 27g Common shaft 7h opening and closing projections 27i 27j 27k opening and closing projection 28 tension spring 29 fixed cover cylinder

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Ihiro Yamazaki 2-36-9 Maenocho, Itabashi-ku, Tokyo Inside Asahiko Gaku Kogyo Co., Ltd. (72) Inventor Satoshi Nakamura 2-36, Maenocho, Itabashi-ku, Tokyo No. 9 Asahi Gaku Kogyo Co., Ltd. F term (reference) 2H044 BD07 BD14 EA02

Claims (8)

[Claims] 1. A plurality of lens groups for changing a focal length of a photographing optical system; and an inner cam groove for guiding at least one lens group among the plurality of lens groups on an inner peripheral surface. A cam ring for moving the lens group in the optical axis direction in accordance with the inner cam groove; a lens support ring having the inner cam groove formed therein; and a lens support ring formed with the inner cam groove. The lens support ring is formed of a separate member, and is constituted by a tip outer circumference ring supported on the outer circumference of the front end of the lens support ring so as to rotate together in the rotational direction. On the other hand, the tip outer peripheral ring is supported in the optical axis direction by a clearance in the optical axis direction.
A zoom lens barrel, wherein an urging spring that bends when an external force is applied from outside the lens barrel is inserted into the outer peripheral ring portion of the zoom lens. 2. The zoom lens barrel according to claim 1, wherein said urging spring is a compression coil spring. 3. The zoom lens barrel according to claim 1, wherein a stopper projection is provided on an outer peripheral surface of the lens support ring portion of the cam ring so as to project radially outward; A linear guide ring that is rotatable relative to the lens support ring and is relatively immovable in the optical axis direction, and that guides the lens group straight in the optical axis direction; and a flange fixed to the front end of the linear guide ring. The distal end outer ring portion is supported so as to be movable by a predetermined distance between the stopper projection and the flange ring in the optical axis direction, and the flange ring is inserted by the urging spring inserted between the stopper projection and the flange projection. A zoom lens barrel that is biased in the direction that comes into contact with the zoom lens. 4. The zoom lens barrel according to claim 3, wherein the outer peripheral portion of the distal end has a rectilinear guide that slidably engages with the stopper protrusion in the optical axis direction. A zoom lens barrel in which the urging spring is disposed. 5. The zoom lens barrel according to claim 1, wherein the outer cylinder is located outside the cam ring and guided straight in the optical axis direction; A guide pin protruding toward the front end; and an advance / retreat guide groove formed on the outer peripheral surface of the outer peripheral end portion of the cam ring for engaging with the guide pin and rotating the cam ring to advance / retreat the external cylinder in the optical axis direction. A zoom lens barrel having: 6. The zoom lens barrel according to claim 5, wherein the flange ring has a straight guide protrusion projecting radially outward, and the straight guide protrusion is provided on an inner peripheral surface of the external appearance tube with an optical axis. A zoom lens barrel that fits into a straight guide groove formed in parallel with the lens barrel and guides the outer appearance tube straight. 7. The zoom lens barrel according to claim 1, wherein said lens support ring portion protrudes radially outward on an outer peripheral surface near a distal end thereof and said distal end outer peripheral ring portion. A supporting step on which the inner peripheral surface of the outer peripheral ring portion is placed, the outer peripheral surface of the lens supporting ring portion and the outer peripheral ring of the distal end being located behind the supporting step portion. The inner peripheral surface of the zoom lens barrel is separated. 8. The zoom lens barrel according to claim 7, wherein: an advance / retreat guide groove formed on the outer peripheral surface of the outer peripheral ring portion of the distal end, the area being used when the zoom lens barrel is in use;
A zoom lens barrel in which the position of the inner peripheral surface of the outer peripheral ring portion in contact with the supporting step portion is different from each other in the optical axis direction.