JP2001215564A - Movable hood disassembly mechanism of zoom lens barrel - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a movable hood disassembly mechanism, which is capable of easily assembling and disassembling a hood of a zoom lens barrel, having the hood from the front of the lens barrel. SOLUTION: This mechanism is provided with plural lens groups, a hood barrel 25 which has a barrier block 27 and is guided rectilinearly in an optical axis direction, a guide pin 25b projected at the hood barrel inwardly of the diametrical direction, and a cam ring 17 which has an advance and retreat guide groove engaging the guide pin in the outer peripheral surface and advances and retreats the hood barrel by rotation in the optical axis direction. Advance and retreat guide groove is provided with an assembly position opened at a front end and a use section, including a zoom section in the circumferential of a cam ring continuous with the assembly position, so that the assembly is made possible by advancing the guide pin of the hood barrel into the advance and retreat guide groove from the front of the cam ring in the assembly position and that the distance between the most front lens group, and the barrier block is changed by advancing and retreating the hood barrel in the optical axis direction according to the change in the focal length of the plural lens groups by the rotation of the cam ring in the use section.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a zoom lens barrel, and more particularly to a movable hood disassembling mechanism.

[0002]

2. Description of the Related Art In a lens barrel of a zoom lens in which the angle of view changes with zooming, it is preferable to limit the incidence of unnecessary light rays according to the angle of view. However, there is no known zoom lens barrel including a hood that can change the maximum incident angle of light rays according to a change in the angle of view.

[0003]

An object of the present invention is to provide a zoom lens barrel having a hood capable of changing a maximum incident angle of a light beam in accordance with a change in an angle of view which changes with zooming. An object of the present invention is to provide a movable hood disassembling mechanism that can be easily assembled and disassembled from the front of a lens barrel.

[0004]

SUMMARY OF THE INVENTION The present invention is directed to a plurality of lens groups for changing the focal length of a photographing optical system; a front end having a barrier block for opening and closing a photographing aperture, and traveling straight ahead in the optical axis direction from the plurality of lens groups A guided hood cylinder; a guide pin protruding radially inward from the hood cylinder; and an advancing / retreating guide groove rotatably held inside the hood cylinder and engaging with the guide pin on an outer peripheral surface. A cam ring for rotating the hood cylinder in the optical axis direction by rotation; the reciprocating guide groove includes an assembling position in which the front end is opened, and a circumferential zoom section of the cam ring continuing to the assembling position. A use section is provided so that the guide pin of the hood cylinder can be inserted into the advance / retreat guide groove from the front of the cam ring at the assembling position so that assembly can be performed. Distance Depending on the change, it is characterized by changing the distance between the forwardmost lens group and the barrier block is moved in the optical axis direction hood cylinder.

[0005] The movable hood disassembling mechanism of the present invention further includes a rotation position detecting mechanism for detecting at least the assembling position and the use section of the cam ring advance / retreat guide groove; Control means for not allowing rotation of the cam ring to the assembling position when the assembly completion signal is given while entering the section, and for allowing rotation of the cam ring to the assembly position when the disassembly instruction signal is given; Is preferably provided.

The cam ring for moving the plurality of lens groups forward and backward is made of a separate member from the cam cylinder for moving the hood cylinder forward and backward, and at least can be moved forward and backward by another cam ring which rotates integrally in the circumferential direction. The barrier of the barrier block that opens and closes the photographing opening is preferably opened and closed by a barrier drive ring that is rotationally driven by a cam ring that moves the hood cylinder forward and backward.

[0007]

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.

[0008]

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 of this embodiment comprises 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.

[0011] 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 straight 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.

Second cam ring 1 fitted to the tip of 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 open 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 linear 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 linear 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.

In the state where the assembly is completed as shown in FIG. 2, when the rotating ring 13 is driven to rotate via the gear 13b, 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, which are shown in an expanded shape 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 unit L1 and the second lens frame 23 (L) holding the second lens unit L2 are composed of 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 straight guiding 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 connecting 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. 6 and 7. FIG. 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 a rotation restricting projection 19a on its inner peripheral surface 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 advancing / retracting guide groove 18b includes an assembling position for inserting the guide pin 25b during assembling, and a storing position corresponding to the storing position, the tele end position, and the wide end position of the cam ring 17. 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, the second cam ring 18 is provided 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. 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 by the external 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 in 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.

Note that 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 articles of 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. However, 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.

[Explanation of Characteristic Portions of the Present Invention] As shown in FIG. 12, the first lens unit L1 and the second lens unit L2 move straight back and forth by the rotation of the cam ring 17 to change the focal length. The external cylinder 25 (barrier block 27) is the cam ring 1
The second cam ring 18 that rotates together with the first cam ring 7 moves straight back and forth. Cam groove 17C1 and 17C of cam ring 17
2 and the reciprocating cam groove 18b of the second cam ring 18
The movement locus as shown in FIG. 2 is determined.

FIG. 19 is an exploded view of one of the advance / retreat guide grooves 18b of the second cam ring 18. The assembling position X in the direction parallel to the optical axis whose front end is opened is continuous with the assembling position X. And a use section U including a zoom section Z in the circumferential direction of the cam ring. Both ends of the zoom section Z are a wide position W and a tele position T near the assembly position X, and a storage position A is further provided outside the tele position T. When the second cam ring 18 is relatively rotated with respect to the external cylinder 25 and the assembly position X of the advance / retreat guide groove 18b matches the guide pin 25b, the external cylinder 25 is assembled from the front of the second cam ring 18. be able to. At this time, the rectilinear guide groove 25a is fitted into the rectilinear guide projection 19b to guide the external cylinder 25 in the optical axis direction. After the assembly, when the second cam ring 18 is rotated to the use section U, the external cylinder 25 can be advanced and retracted in the optical axis direction according to the path of the advance and retreat guide groove 18b. That is, in the use section U, the rotation of the cam ring 17 changes the focal length of the lens system, and the rotation of the second cam ring 18 that rotates together with the cam ring 17 causes the external cylinder 25 to move the optical axis. By moving back and forth in the direction to change the distance between the frontmost lens group and the barrier block 27, unnecessary light outside the angle of view is prevented from entering the lens system. When the guide pin 25b enters the use section U, the external cylinder 25 cannot be moved forward to be disassembled.

Whether to rotate the second cam ring 18 to the assembly position or to rotate it within the use section U can be controlled by using a mechanical stopper. Is preferably controlled. The rotation position of the second cam ring 18 is detected by the rotation position of the rotation ring 13. FIG.
0, the code plate 14 and the brush 15 as shown in FIG.
Constitutes a rotation position detection mechanism together with the rotation position detection circuit 30, and includes an assembly position X of the rotation ring 13 (second cam ring 18).
The wide position W, the tele position T and the storage position A are detected.
Pinion 13d meshing with outer peripheral gear 13b of rotating ring 13
Is rotated in the forward and reverse directions by a motor 32, and its rotational position (angle) is detected by an encoder 33. Control means 3
Reference numeral 1 denotes an assembly completion signal given in response to a signal from the rotation position detection circuit 30 and the encoder 33, in a state where the guide pin 25b of the external cylinder 25 enters the use section U of the advance / retreat guide groove 18b of the second cam ring 18. Then, the rotation of the second cam ring 18 to the assembly position X is not allowed. Then, when the disassembly signal is given, the rotation of the second cam ring 18 to the assembly position X is permitted (the second cam ring 18 is rotated to the assembly position X).
Of course, the disassembly signal to the control means 31 can be given only by the maker side, and cannot be given by the user.

According to the above-described cam ring disassembling mechanism, the external appearance cylinder 25 having the barrier block 27 can be attached to and detached from the front of the second cam ring 18, so that assembly and disassembly is easy. Then, once the appearance tube 25 is removed, the position of the lens tube 22e in the optical axis direction can be adjusted by rotating the lens tube 22e according to the screw 22f.

In the above embodiment, the cam ring 17 for changing the focal length of the lens system and the second cam ring 18 for moving the appearance tube 25 forward and backward in the optical axis direction are separate bodies. It can be a ring. That is, the cam ring 17
It is also possible to provide an advance / retreat guide groove 18b. Further, the present invention is not limited to any means for changing the focal length of the lens system, and any structure may be used as long as the second cam ring (cam ring) for advancing and retracting the external cylinder is linked to the change in the focal length.

In the above embodiment, the present invention is applied to a zoom lens barrel of a digital camera, but the present invention can be similarly applied to a lens shutter camera.

[0044]

As described above, according to the present invention, there is provided a zoom lens barrel provided with a hood tube capable of changing the maximum incident angle of light rays in accordance with a change in the angle of view which changes with zooming. Thus, it is possible to obtain a zoom lens barrel in which the hood cylinder can be easily assembled and disassembled.

[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 a development view showing an example of the shape of the advance / retreat guide groove of the second cam ring.

FIG. 20 is a development view of a code plate.

FIG. 21 is a block diagram illustrating a rotation position detection mechanism of a rotating ring (a cam ring and a second cam ring) and a rotation position control mechanism of the rotating ring.

[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 through groove 16d Bayonet claw 16e Small diameter insertion portion 16f Small diameter portion 16g Rotation restricting recess 16h Cam follower insertion groove 17 Cam ring 17a Stopper protrusion 17b Male helicoid 17c Rotation transmission groove 17d Introduction portion 18 second cam ring 18a rectilinear guide portion 18b reciprocating guide groove 18c rotation imparting concave portion 19 rectilinear guide ring 19a rotation restricting convex portion 19b rectilinear guide protrusion 20 retainer ring 20a fixing claw 20b claw groove 21 Compression spring 22 First lens frame 22a Tubular portion 22b Elastic tongue piece 22c Square projection (parallel plane projection) 22d Follower pin 22f Screw 22g Flange 22h Wave washer 23 Second lens frame 23a Annular part 23b Elastic tongue piece 23c Square projection (parallel plane) Projection) 23d Follower pin 23e Lens cylinder 23f Fixing screw 23g Flange 24 Shutter block 25 Exterior cylinder (hood cylinder) 25a Straight guide groove 25b Guide pin 25c Spring hook projection 26 Barrier drive ring 26a Rotation transmission projection 26b Spring hook projection 26c Open / close dowel 26d Light shielding Cylinder 27 Barrier block 27a Imaging opening 27b Decorative plate 27c 27d Barrier 27e Torsion spring 27f Barrier holding plate 27g Common shaft 27h Open / close protrusion 27i 27j 27k Open / close protrusion 28 Tension spring 29 Fixed Cover cylinder 30 rotation position detection circuit 31 control means 32 motor 33 encoder

 ──────────────────────────────────────────────────続 き Continued 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 BD06 BD10 2H083 CC28 CC42

Claims (4)

[Claims] 1. A plurality of lens groups for changing the focal length of a photographic optical system; a barrier block at an end portion for opening and closing a photographic opening, and guided straight in the optical axis direction in front of the plurality of lens groups. A hood cylinder; a guide pin protruding radially inward from the hood cylinder; and an advancing / retreating guide groove which is rotatably held inside the hood cylinder and engages with the guide pin on an outer peripheral surface. A cam ring for moving the hood cylinder forward and backward in the optical axis direction, wherein the forward / backward guide groove has an assembly position in which a front end is opened;
A use section including a circumferential zoom section of the cam ring that is continuous with the assembling position is provided. At the assembling position, the guide pin of the hood cylinder can be inserted into the advance / retreat guide groove from the front of the cam ring to be assembled. In the use section, the rotation of the cam ring causes the hood cylinder to advance and retreat in the optical axis direction according to the change in the focal length of the plurality of lens groups, thereby changing the distance between the forefront lens group and the barrier block. A movable hood disassembly mechanism for a zoom lens barrel. 2. The movable hood disassembling mechanism according to claim 1, further comprising: a rotation position detecting mechanism for detecting at least the assembling position and a use section of the advance / retreat guide groove of the cam ring; When the assembling completion signal is given in a state of entering the use section of the reciprocating guide groove, the cam ring is not allowed to rotate to the assembling position when disassembly instruction signal is given, and the cam ring is turned to the assembling position. A movable hood disassembling mechanism for the zoom lens barrel, the control means comprising: 3. The movable hood disassembling mechanism according to claim 1, wherein the plurality of lens groups are formed of a separate member from a cam cylinder for moving the hood cylinder forward and backward, and at least another cam that rotates integrally in the circumferential direction. A movable hood disassembly mechanism for a zoom lens barrel that moves forward and backward in the optical axis direction by a ring. 4. The movable hood disassembling mechanism according to claim 1, wherein the barrier of the barrier block for opening and closing the photographing opening is formed by a barrier drive ring that is rotationally driven by a cam ring that moves the hood cylinder forward and backward. A movable hood disassembly mechanism for the zoom lens barrel that opens and closes.