JP2597355Y2 - Anti-reflection device for zoom lens barrel - Google Patents

Description

[Detailed description of the invention]

[0001]

TECHNICAL FIELD The present invention relates to an antireflection device for a zoom lens barrel.

[0002]

2. Description of the Related Art The lens barrel of a camera includes:
Various rotary cylinders are provided for performing zooming and focusing. Conventionally, in order to reduce harmful reflection on the inner surface of these rotating cylinders, an inner surface anti-reflection device provided on the rotating cylinder itself, such as one having a rough surface for preventing inner surface reflection in the inner cam groove of the rotating cylinder. Has been proposed.

In the lens barrel under development by the present applicant, a rotation transmission shaft for transmitting a rotational force between two different members, for example, is disposed in the rotation cylinder, and a sliding shaft is mounted on the rotation transmission shaft. Some have fitted gears where possible. However, subsequent research has shown that in this structure, the exposed portion of the rotation transmission shaft may cause harmful internal reflection.

[0004]

SUMMARY OF THE INVENTION An object of the present invention is to provide an anti-reflection device for a zoom lens barrel that prevents harmful internal reflection caused by an exposed portion of a rotation transmission shaft based on the above problem awareness.

[0005]

SUMMARY OF THE INVENTION In order to achieve the above object, the present invention provides a rotating cylinder driven to rotate; a first advancing and retracting cylinder which moves straight in the optical axis direction by the rotation of the rotating cylinder; A second advancing and retracting cylinder that moves in the direction of the optical axis when rotated, and moves along a predetermined trajectory in the direction of the optical axis by the rotation of the second advancing and retracting cylinder to change the focal length.
A movable lens group of a group; a pair of gears rotatably supported on the first advancing and retracting cylinder side and the second advancing and retracting cylinder side, respectively; and at least a second transmission for transmitting one rotation of the pair of gears to the other. A rotation transmission shaft fitted with a gear supported on the forward / backward cylinder side so as to be movable in the axial direction; and a harmful reflection of the rotation transmission shaft on the first forward / backward cylinder side and the second forward / backward cylinder side, respectively. It is characterized in that an anti-reflection portion for preventing the light is provided.

The first advance / retreat cylinder has a gear support plate for supporting the one gear together with the first advance / retreat cylinder,
In the case where the forward / backward moving cylinder has a straight running guide member that supports the other gear together with the second moving forward / backward moving section, the antireflection section moves the gear support plate and a part of the straight running guide member in a direction approaching each other in the optical axis direction. And a pair of light-shielding plates extending to the front.

[0007]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below with reference to the illustrated embodiments. In the present embodiment, the front group lens L1 and the rear group lens L
2 constitutes a zoom lens system, and focusing is performed by the front lens group L1.

As shown in FIGS. 7 and 8, a fixed lens barrel 11 integrated with a camera body 10 to which the present invention is applied has an inner cylinder 11a and an outer cylinder 11b. The rear ends of the inner cylinder 11a and the outer cylinder 11b in the optical axis direction are connected by a connection wall 11c, and the front ends are open.
A rotating cylinder 12 is rotatably fitted around the outer periphery of the inner cylinder 11a. The inner cylinder 11a is provided with a straight guide groove 11e in a direction parallel to the optical axis O.

The rotary cylinder 12 is provided with a circumferential flat gear 12a integrally formed on the outer circumference thereof, and a fine screw 12b formed integrally on the outer circumference of the distal end thereof. On the inner surface thereof, a lead groove 12c inclined in the circumferential direction and an inclined inner gear 12d parallel to the lead groove 12c and inclined in the circumferential direction are formed.

At the open front end of the inner barrel 11a and the outer barrel 11b of the fixed lens barrel 11, a fitting portion 13a for fitting to the inner surface of the outer barrel 11b is provided.
A screw portion 13b screwed to the fine screw 12b;
A contact portion 13c contacting the outer surface of the outer flange 1a;
A support ring 13 having 3e is fixed. The support ring 13 is held at a fixed position by being pressed toward the fixed lens barrel 11 by a biasing means (not shown). 13d
Is a gear for rotating operation formed on the outer peripheral surface of the support ring 13. With this support ring 13, it is possible to eliminate insufficient strength of the openings of the inner cylinder 11a and the outer cylinder 11b.

The outer cylinder 11b of the fixed lens barrel 11 has a spur gear 1
A notch 11d for the pinion 11f that meshes with 2a is provided, and a similar notch that exposes the lead groove 12c and the inclined inner gear 12d (FIGS. 1 and 2) is provided in the inner cylinder 11a.

A first advance / retreat cylinder 14 that moves straight in the optical axis direction is fitted on the inner periphery of the inner cylinder 11a of the fixed lens barrel 11. On the outer periphery of the first advancing / retreating cylinder 14, a rectilinear guiding projection 14a which fits into the rectilinear guiding groove 11e of the fixed lens barrel 11 is integrally provided.
Pin 14b that fits into the second lead groove 12c (FIGS. 1 and 2)
Is provided. A female helicoid 14c and a straight guide groove 1 parallel to the optical axis are provided on the inner circumference of the first advance / retreat cylinder 14.
4d (FIGS. 1 and 3) are formed. According to the above relationship, when the rotary cylinder 12 is rotationally driven, the straight guide groove 1
According to 1e and the lead groove 12c, the first advance / retreat cylinder 14 advances / retreats in the optical axis direction without rotating.

A second advancing and retracting cylinder (cam ring) 15 is fitted on the inner periphery of the first advancing and retracting cylinder 14. A male helicoid 15a that is screwed to the female helicoid 14c of the first advance / retreat cylinder 14 is formed at the rear of the outer periphery of the second advance / retreat cylinder 15 in the optical axis direction. A rectilinear guide member 16 is located on the inner periphery of the second reciprocating cylinder 15, and a rear end of the rectilinear guide member 16 is
The gear support / straight guide plate 17 is fixed with fixing screws 19. The straight advance guide member 16 is provided on the second advance / retreat cylinder 15.
An inner flange 15b (see FIGS. 7 and 8) is formed to be rotatable relative to and the linear guide plate 17.
Further, a plurality of rectilinear guide keys 17a formed on the peripheral portion of the rectilinear guide plate 17
It is stuck in. Therefore, the rectilinear guide member 16 and the rectilinear guide plate 17 can freely rotate relative to the second reciprocating barrel 15 and move integrally in the optical axis direction. That is, the second advance / retreat cylinder 15
Rotates, the male helicoid 15a and the female helicoid 1
According to 4c, it moves in the optical axis direction while rotating, while the linear guide member 16 and the linear guide plate 17 move in the optical axis direction together with the second advance / retreat cylinder 15 without rotating.

The rectilinear guide member 16 has three rectilinear keys 16b and 16b 'extending in a direction parallel to the optical axis O. The front group linear guide member 18 has three linear keys 18a that engage with the three linear keys 16b and 16b 'and extend in a direction parallel to the optical axis O. A shutter block 20 is fixed to the front group straight guide member 18 by a fixing screw 21. The shutter block 20 is further fixed to the front group lens support tube 22. Therefore, the shutter block 20 and the front group lens support tube 22 is restricted in rotation, and can only move in the optical axis direction.

As shown in FIGS. 1 and 4, the shutter block 20 has a female helicoid 20a on its shaft, and the front group lens frame 23 in which the front lens L1 is fixed to the female helicoid 20a. The male helicoid 23a is screwed. A male helicoid 22a for moving the front lens frame 23 in the optical axis direction during zooming is formed at the rear end of the outer peripheral surface of the front lens support cylinder 22. The shutter block 20 has a shutter blade 20c,
A drive signal is given to the shutter block 20 via the FPC board 20d.

On the other hand, the front group straight guide member 18 is formed with a rear group guide surface 18b for moving the rear group lens L2 straight in the optical axis direction. The rear group lens L2 is fixed to the rear group lens frame 24.
Then, the rectilinear key 24a engaged with the rear group guide surface 18b
Is provided. And on this straight key 24a,
A cam pin 24b is formed to protrude.

A female helicoid 15c for screwing a male helicoid 22a of the front group lens support cylinder 22 onto the inner peripheral surface of the second advance / retreat cylinder 15 and a cam pin 24 of the rear group lens frame 24
and a cam groove 15d into which the b is inserted. The cam groove 15d is mixed with the helicoid at the same circumferential position so as to cut off a part of the female helicoid 15c. At the time of assembly, the cam pin 24b of the rear lens frame 24 is fitted into the open groove 22b at the rear end of the front lens support cylinder 22, and in this state, the cam pin 24b is inserted into the cam groove 15d, the male helicoid 22a is inserted into the female helicoid 15c, Each is engaged. In this engaged state, the female helicoid 15 c and the male helicoid 22 c
a and the straight key 16 of the straight guide member 16
Due to the rectilinear guide relationship between b and the rectilinear key 18a of the front group rectilinear guide member 18, the front lens support cylinder 22 (front lens L1) moves rectilinearly in the optical axis direction, and the engagement between the cam groove 15d and the cam pin 24b. The rear group lens frame 24 is formed based on the mating relationship and the straight guide relationship between the straight key 24a of the rear group lens frame 24 and the rear group guide surface 18b of the front group straight guide member 18.
(The rear lens group L2) moves along a predetermined locus in the optical axis direction,
Zooming is performed.

As described above, when the rotary barrel 12 is rotationally driven, the first advance / retreat barrel 14 moves straight in the optical axis direction, and when the second advance / retreat barrel 15 rotates with respect to the first advance / retreat barrel 14, the first advance / retreat barrel 15 rotates. It can be seen that the binary retreat cylinder 15 moves in the optical axis direction while rotating, and the front lens group L1 and the rear lens group L2 move straight while changing the air gap, thereby performing zooming.

Next, a drive mechanism for rotating the second advance / retreat cylinder 15 will be described. This rotation drive mechanism basically transmits the rotation of the rotary cylinder 12 to the second advance / retreat cylinder 15. A pair of gear support plates 26 and 27 are fixed to the rear end of the first advancing / retreating cylinder 14 by fixing screws 29. The gear support plate 26 rotatably supports a pinion 30 (see FIGS. 5 and 6) that meshes with the inclined inner gear 12 d of the rotary cylinder 12. The first advance / retreat cylinder 14
A plurality of linear guide keys 14a formed in the circumferential direction at the rear end
The pinion 3 is located between the two straight guide keys 14.
A linear guide protrusion 14a '(FIG. 3) having a pinion storage space 14e for storing the 0 is formed. A part of the tooth surface of the pinion 30 stored in the pinion storage space 14 e protrudes from the outer surface of the first advance / retreat cylinder 14. Rotating cylinder 12
The inner gear 12d (FIG. 2) is parallel to the lead groove 12c.
Even if 4 moves in the optical axis direction, the meshing relationship between the pinion 30 and the inclined inner gear 12d is maintained. A gear train 31 receiving the rotation of the pinion 30 is supported between the gear support plates 26 and 27. A rotation transmission shaft 32 extending forward along the optical axis O is provided on the shaft of the final gear 31a. Are integrally fixed. This rotation transmission shaft 3
2 has a non-circular uniform cross section.

On the other hand, a linear guide plate 17 fixed to the rear end face of the linear guide member 16 has the rotation transmitting shaft 3.
The take-out pinion 33, which can move relative to the shaft 2 in the axial direction and rotates integrally with the rotation transmission shaft 32, is supported. That is, the takeout pinion 33 always moves together with the straight guide plate 17 (and the second advance / retreat cylinder 15) in the optical axis direction. The take-out pinion 33 is connected to the second advance / retreat cylinder 15.
Is meshed with the circumferential inner gear 15e formed on the inner surface of the inner gear. Accordingly, the rotation of the rotary cylinder 12 is performed regardless of the position of the first advance / retreat cylinder 14 in the optical axis direction.
d, pinion 30, gear train 31, rotation transmission shaft 3
2. It is transmitted to the second advance / retreat cylinder 15 via the take-out pinion 33 and the circumferential inner gear 15e.

The zoom lens barrel having the above-described structure is
As described above, when the rotary barrel 12 is driven to rotate in the forward and reverse directions, the first advance / retreat barrel 14 moves straight in the optical axis direction, and the second advance / retreat barrel 15 rotates. When the second advance / retreat cylinder 15 rotates, it moves in the optical axis direction, and the front group lens L1 and the rear group lens L2 move straight while changing the air gap, and zooming is performed. Thus, the front lens group L1 and the rear lens group L2 are
It can be moved from the storage state of FIG. 7 to the tele end position of FIG. 8, and in the storage state, the first advance / retreat cylinder 14,
Since the second advance / retreat barrel 15 and the front group lens support barrel 22 do not protrude from the outer shell of the main body (camera body 10), the storage length is extremely short. In addition, 41 shown in FIGS. 7-9 is a decorative board.

Next, the antireflection device which is a feature of the present invention will be described. This anti-reflection device is for preventing a problem that an exposed portion of the rotation transmission shaft 32 located in the photographing optical path causes harmful internal reflection in the photographing optical path and adversely affects film exposure. is there. As shown in FIGS. 9 to 12, the linear guide member 1 rotatably supports the pinion 33 together with the second advance / retreat cylinder 15 and moves in the optical axis direction, that is, along the rotation transmission shaft 32.
The gear support plate 27 rotatably supports the final gear 31a together with the first and second reciprocating cylinders 14, and a pair of light-shielding portions each of which has a part on the innermost side extending in a direction approaching each other in the optical axis direction. It has plates 16a and 27a. These light shielding plates 16a and 27a constitute the above-described antireflection device, and are each formed as a surface having an arc-shaped cross section.
The inner and outer peripheral surfaces of the light shielding plates 16a and 27a, that is, the surface facing the rear group lens L2 and the surface facing the rotation transmission shaft 32, respectively, have light shielding lines, wrinkles, Alternatively, anti-reflection measures such as fine irregularities are taken.

The light-shielding plate 27a has a greater optical axis O than the light-shielding plate 16a.
9 and 11 in FIG.
In the middle state of the zooming shown in (1), when they approach each other, they overlap each other, and the light a incident from the imaging aperture and emitted from the rear lens group L2 hits the inner surface of the light shielding plate 27a and does not reach the rotation transmission shaft 32. Therefore,
It is possible to prevent the problem that the rotation transmission shaft 32 causes harmful internal reflection due to the exposed portion thereof and adversely affects the exposure of the film. When the front and rear lens units L1 and L2 are separated from each other in the longest extension (tele end) state shown in FIGS. 10 and 12, the light b and c incident from the photographing aperture and emitted from the rear lens unit L2 are transmitted by rotation. The light is reflected by the exposed portion of the shaft 32.
Since the light is reflected to the front side of the optical axis by the outer surface and the end of the shaft 7a, harmful inner surface reflection by the rotation transmission shaft 32 is prevented.

That is, the extension of the light shielding plates 16a and 27a does not need to be long enough to correspond to the axial length of the rotation transmission shaft 32, and the reflected light reflected by the rotation transmission shaft 32 in the telephoto end state. Need only be long enough to reflect the light forward in the optical axis direction. Therefore, the light shielding plate 16
Only by extending and forming the linear guide members a and 27a to the rectilinear guide member 16 and the gear support plate 27 with minimum necessary lengths, it is possible to reliably prevent the harmful internal reflection caused by the rotation transmission shaft 32 from occurring. . Therefore, it is possible to obtain an antireflection device having a very simple structure,
This can contribute to downsizing of the zoom lens barrel.

[0025]

As described above, according to the present invention, since the anti-reflection portions for preventing harmful reflection of the rotation transmission shaft are provided on each of the first advancing and retracting cylinder side and the second advancing and retracting cylinder side, the zoom lens barrel is provided. In this case, harmful internal reflection caused by the rotation transmission shaft can be reliably prevented.

The first forward / backward cylinder has a gear support plate for supporting one of the pair of gears together with the first forward / backward cylinder, and the second forward / backward cylinder supports the other gear together with the second forward / backward cylinder. When a straight guide member is provided, the anti-reflection portion is constituted by a pair of light shield plates in which a part of each of the gear support plate and the straight guide member extends in a direction approaching each other in the optical axis direction. Since each extension amount does not require a length corresponding to the axial length of the rotation transmission shaft and only a minimum length is sufficient, it is possible to obtain an antireflection device having a very simple structure, This can contribute to downsizing of the zoom lens barrel.

[Brief description of the drawings]

FIG. 1 is an overall exploded perspective view showing an example of a lens barrel to which the present invention is applied.

FIG. 2 is an enlarged perspective view of a rear part of the lens barrel in FIG.

FIG. 3 is an enlarged perspective view of an intermediate portion of the lens barrel in FIG.

FIG. 4 is an enlarged perspective view of a front part of the lens barrel of FIG. 1;

FIG. 5 is a perspective view showing a support mechanism of a power transmission system of the lens barrel.

FIG. 6 is a perspective view showing the relationship of only the gears of the power transmission system.

FIG. 7 is a longitudinally upper half view of the lens barrel in a housed state.

FIG. 8 is an upper half view of the vertical section in the longest feeding state.

FIG. 9 is a top half view in longitudinal section showing a state in the middle of zooming of the lens barrel to which the present invention is applied.

FIG. 10 is an upper half sectional view showing the longest extended state of the lens barrel.

FIG. 11 is an upper half view in longitudinal section showing the state of the antireflection device in the middle of zooming in FIG. 9;

FIG. 12 is a longitudinal upper half view showing the state of the anti-reflection device in the longest extended state of FIG. 10;

[Explanation of symbols]

 Reference Signs List 12 rotating cylinder 14 first advance / retreat cylinder 15 second advance / retreat cylinder 16 linear guide member 16a 27a light shielding plate (anti-reflection part) 27 gear support plate 31a final gear (gear) 32 rotation transmission shaft (rotation transmission shaft) 33 takeout gear (gear) L1 Movable lens group (front group lens) L2 Movable lens group (rear group lens) O Optical axis

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. ⁶ , DB name) G02B 7/09 G02B 7/02 G02B 7/10

Claims (2)

(57) [Scope of request for utility model registration] A rotating cylinder driven to rotate; a first advancing and retreating cylinder which moves straight in the optical axis direction by the rotation of the rotatable cylinder; A second retreating cylinder that moves in a direction; moving the lens along a predetermined locus in the optical axis direction by the rotation of the second retreating cylinder to change the focal length;
At least two front and rear movable lens groups; a pair of gears rotatably supported on the first advancing and retracting cylinder side and the second advancing and retracting cylinder side; at least transmitting one rotation of the pair of gears to the other; A rotation transmission shaft fitted with a gear supported on the second advance / retreat cylinder side so as to be movable in the axial direction; and a harmful effect of the rotation transmission shaft on the first advance / retreat cylinder side and the second advance / retreat cylinder side, respectively. An anti-reflection device for a zoom lens barrel, comprising an anti-reflection unit for preventing reflection. 2. The device according to claim 1, further comprising a gear support plate for supporting said one gear together with said first advance / retreat cylinder, and a second advance / retreat cylinder together with said second advance / retreat cylinder. The anti-reflection portion has a linear guide member that supports the gear, and the anti-reflection portion is formed by a pair of light shielding plates that extend a part of each of the gear support plate and the linear guide member in a direction approaching each other in the optical axis direction. An anti-reflection device for the zoom lens barrel that is configured.