JPH0755527Y2 - Structure to prevent backlash between cam groove and roller in relative sliding ring of lens barrel - Google Patents

Description

TECHNICAL FIELD The present invention relates to a lens barrel, and more particularly to a cam groove cut into a plurality of annular members that slide relative to each other and a fitting backlash prevention structure for a roller fitted in the cam groove. .

"Prior Art and its Problems" In a lens barrel, particularly in a zoom lens barrel, in order to slidably fit a plurality of constituent annular members, for example, to obtain a predetermined lens movement locus for zooming, A cam groove is formed in these annular members, and a roller fixed to another annular member is fitted into this cam groove. The cam groove has a simple curve, a complicated curve,
Alternatively, it is formed as a straight groove.

By the way, a conventional roller fitted into such a cam groove is provided with a countersink hole on the surface opposite to the fixing surface with the annular member, and is fixed by a countersunk screw inserted into the countersink hole, There is a type in which a fixing screw is inserted and fixed in the center of a ring-shaped roller without a gap. However, in the former case, the roller may be deformed into a trapezoidal cross section due to the contact pressure with the countersunk screw, and the roundness may be lost. For this reason, the annular member does not move along a predetermined locus, and a focus movement occurs, or unevenness in zooming occurs. This tendency is remarkable in the complicated curved cam in which the contact position between the roller and the cam groove is likely to change, and particularly when the groove width of the cam groove is changed.

In the latter case, the roller and the fixing screw are fitted together without a gap, and the gap between the roller and the cam groove is made as small as possible. Therefore, in the case of dimensional variation within the range of processing error, the two must be matched in actual use. I have to. However, even if the actual width is adjusted, if there is a change in the groove width of the cam groove, there will be backlash in the wide groove portion and an accurate trajectory cannot be obtained, and in the narrow portion the sliding resistance will increase. , The feeling of sliding operation such as zooming becomes worse.

[Object of the Invention] The present invention solves the above problems of the conventional roller-cam groove fitting structure, and can accurately guide a plurality of annular members that relatively slide in accordance with the cam groove. It is an object of the present invention to provide a fitting backlash prevention structure that has good workability and that can provide a smooth sliding feeling.

[Outline of the Invention] In order to achieve the above object, the present invention has a plurality of annular members fitted so as to be relatively slidable, a cam groove provided in one of the plurality of annular members, and fixed to the other. In a lens barrel having a roller that fits in the cam groove, the roller is configured to be fixed to the annular member by a fixing screw that is inserted through the center of the lens barrel, and the roller is in a state where no external force is applied. An annular elastic portion having a diameter larger than the width of the cam groove, the peripheral surface of which elastically abuts the cam groove when fitted in the cam groove, and which is located at least on the outer periphery of the head of the fixing screw; A small diameter portion having a smaller diameter than the annular elastic portion and located on the outer periphery of the neck portion of the fixing screw; and the annular portion between the outer periphery of the head portion of the fixing screw and the inner surface of the annular elastic portion. Elastic deformation of the elastic part is allowed, but elastic It is characterized by providing an annular gap that suppresses elastic deformation exceeding the limit.

"Embodiment of the Invention" The present invention will be described below with reference to illustrated embodiments. Figure 1 shows
The specific application examples of the two different embodiments of the cam groove / roller fitting backlash preventing structure of the present invention are drawn on a single one-hand zoom lens barrel. Therefore, it is slightly different from the actual cam groove on the lens barrel structure.

A straight cam ring 20 is slidably fitted on the outer side of the fixed guide ring 10 of the zoom lens barrel, and a rotary cam ring 30 is slidably fitted on the inner side thereof.
31 is slidably fitted.

The fixed guide ring 10 has a circumferential groove 11 and a straight cam groove 12 parallel to the optical axis.

The rotary cam groove 30 is provided with a complicated curved cam groove 23 and a straight-moving cam groove 13 parallel to the optical axis. The complicated curved cam groove 23 and the circumferential groove 11 are overlapped with each other at the first portion of the present invention. The roller 61 which is the embodiment of FIG. The roller 61 is fixed to the rotary cam ring 30.

A roller 71 according to the second embodiment of the present invention is fitted in the straight cam groove 13, and the roller 71 is fixed to the fixed guide ring 10.

Further, the rotary cam ring 30 is formed with a complicated curved cam groove 24, and a roller 61 substantially the same as the roller 61 is fitted in an overlapping portion of the complicated curved cam groove 24 and the straight-moving cam groove 12. The roller 61 is fixed to the rear lens group frame 31.

FIG. 6 shows an example of the shape of the complex curved cam groove 23 or 24.

The fixed guide ring 10 is fixed to a fixed lens barrel including a lens mount ring 51, and a helicoid 21 provided at the tip of the rectilinear cam ring 20.
A focusing lens frame 5 is screwed into the. The focusing lens frame 52 is fixed to the operation ring 53,
When the operation ring 53 is rotated, the focusing lens frame 52 moves along the helicoid 21 in the optical axis direction, and focusing is performed by the focusing lens group L1. When the operation ring 53 is moved in the optical axis direction, the complicated curved cam groove 23
And the rotary cam ring 30 rotates in accordance with the circumferential groove 11, and the rotation of the rotary cam ring 30 causes the rear lens group frame 31 to move in the optical axis direction in accordance with the complex curved cam groove 24 and the rectilinear cam groove 12 for focusing. The air space between the lens unit L1 and the variable power lens unit L2 supported by the rear lens group frame 31 changes to perform zooming.

As shown in FIG. 2, the roller 61 fitted in the overlapping portion of the complicated curved cam groove 23 and the circumferential groove 11 and the overlapping portion of the complicated curved cam groove 24 and the straight-moving cam groove 12 has its shaft portion as shown in FIG. Fixing screw 62 with its neck 62b inserted through the insertion hole 61a
It is fixed to the rotary cam ring 30 and the rear lens group frame 31 by means of the annular elastic portions 6 at the upper and lower sides in the axial direction.
It has 4 and 65. The annular elastic portion 64 has a complicated curved cam groove 23.
The annular elastic portion 65 is fitted in the circumferential groove 11.

The annular elastic portions 64 and 65 are elastically deformable in the radial direction,
When it is fitted into the corresponding complicated curved cam groove 23 and circumferential groove 11, it has an outer diameter such that it is slightly deformed in the diameter reducing direction, and the elastic force thereof causes the complicated curved cam groove 23 and circumferential direction respectively. It makes elastic contact with the inner surface of the groove 11. An annular gap L is formed between the inner circumference of the annular elastic portion 64 and the outer circumference of the head portion 62a of the fixing screw 62.

A small diameter portion 66 is formed between the annular elastic portions 64 and 65. The small-diameter portion 66 divides the diameter changes of the annular elastic portions 64 and 65 without affecting each other, and exerts an appropriate and independent elastic force on each.

A deformation suppressing ring 67 fitted to the fixing screw 62 is located inside the annular elastic portion 65. The deformation suppressing ring 67 corresponds to the outer diameter of the head portion 62a of the fixing screw 62, and has the annular elastic portion 6
An annular gap L is formed between the first and second portions.

These gaps L, that is, the upper and lower annular elastic portions of the roller 61
The gap L inside 64 and 65 allows the inward elastic deformation of these annular elastic portions, and even when an elastic deformation force exceeding the elastic limit is applied, it is not deformed until permanent deformation occurs. Has a suppressive effect.

On the other hand, the guide roller 71 applied to the rectilinear cam groove 13 is a fixing screw in which the neck portion 72b is inserted into the insertion hole 71a of the shaft portion.
It is fixed to the fixed guide ring 10 by 72, has a single annular elastic portion 74, and further has a small diameter portion 73 under the annular elastic portion 74. The annular elastic portion 74 is formed by the roller 61.
Like the annular elastic portions 64, 65, the elastic diameter is elastically deformable in the radial direction, and when the linear elastic cam groove 13 is fitted, the outer diameter is such that the elastic diameter is slightly deformed in the diameter reducing direction. The force makes elastic contact with the inner surface of the straight cam groove 13. Then, the annular elastic portion 74
A ring-shaped gap L is formed between the inner circumference of and the outer circumference of the head 72a of the fixing screw 72. The gap L and the small diameter portion 73
The action of is the same as the gap L and the small diameter portion in the first embodiment.
Similar to 66.

Therefore, when the roller 61 is fitted over the overlapping cam grooves 23 (24) and 11 (12), the small diameter portion is formed.
By the 66, the elastic force of the annular elastic portion 64 with respect to the inner surface of the complex curved cam groove 23 (24) and the elastic force of the annular elastic portion 65 with respect to the inner surface of the groove 11 (12) act independently, and each of them corresponds to the complex curved cam. The groove 23 (24) and the groove 11 (12) are elastically contacted. Therefore, the overlapping groove width A of the cam groove 23 (24) and the overlapping cam groove 11 (1
Even if there is a difference in groove width between the groove widths B in 2) or there is a change in groove width between the starting point and the ending point of these grooves,
The fitting backlash between 61 and these cam grooves 23 (24) and 11 (12) is removed.

Even when the guide roller 71 is used, since the annular elastic portion 74 elastically contacts the inner surface of the straight-moving cam groove 13 with an appropriate elastic force, the groove width C of the cam groove 13 varies from the starting point to the ending point. Even so, the annular elastic portion 74 and the cam groove 12 maintain the proper fitting state. As described above, according to the roller 61 and the guide roller 71, since the roller 61 and the guide roller 71 are always in elastic contact with the inner surface of the groove, there is no looseness in the fitting, and as a result, the focus does not move, and a good zooming feeling is always obtained. To be

The structure of the lens barrel shown in the above embodiment is, of course, merely an example. The present invention can be widely applied to a lens barrel having a plurality of slidably fitted annular members.

[Advantage of Device] As described above, according to the present invention, it is possible to remove the fitting play even in the cam groove whose groove width changes from the start point to the end point. A rattling prevention structure can be obtained. Therefore, in the lens barrel, it is possible to reduce inconvenience of operation due to looseness of fitting of the cam groove and the roller, and heavy operation feeling due to tight fitting. Moreover, since the roller has a compact shape integrally including the annular elastic portion and the small diameter portion, the manufacturing process thereof is simplified. Furthermore, since the annular gap is provided between the outer periphery of the head of the fixing screw and the inner surface of the annular elastic portion, the amount of elastic deformation of the annular elastic portion in the radial direction is properly regulated. In addition, the roller and the fixing screw can be used in combination with sufficient compatibility within the processing tolerance, so that a mating play preventing structure of the cam groove and the roller that is excellent in workability and assembling can be obtained. .

Furthermore, when two annular elastic portions are provided with the small diameter portion sandwiched therebetween, the small diameter portion located in the middle of the both annular elastic portions divides the diameter changes of both annular elastic portions without affecting each other. Therefore, proper elastic forces can be exerted independently of each other. Therefore, for example, even when the two annular members fitted to each other both have a cam groove and the roller is fitted so as to straddle the overlapping portions of the both cam grooves, the two annular elastic portions sandwiching the small-diameter portion, It is possible to elastically contact the inner surfaces of the different cam grooves in proper states.
In particular, the two annular elastic portions are respectively located on the head of the fixing screw and on the neck opposite to the head sandwiching the small diameter portion, and at a position corresponding to the inner surface of the other annular elastic portion of the neck. If a deformation suppressing ring is provided on one of the annular elastic parts and an annular gap is formed between the inner surface of the annular elastic part and the head part and between the inner surface of the other annular elastic part and the neck part, the elastic deformation amount in the radial direction of each of the annular elastic parts is increased. Can be properly regulated.

[Brief description of drawings]

FIG. 1 is an upper half sectional view showing an embodiment of a play preventing structure of a lens barrel according to the present invention, and FIG. 2 is a sectional view of a guide roller fitted in a plurality of overlapping cam grooves in the embodiment of FIG. FIG. 3 is a sectional view of a guide roller fitted in a single cam groove in the embodiment of FIG. 1, and FIG. 4 is IV- of FIG.
FIG. 5 is an enlarged sectional view taken along line IV, FIG. 5 is an enlarged sectional view taken along line VV in FIG. 1, and FIG. 6 is a state in which a roller is fitted in a complicated curved cam groove as an example of overlapping cam grooves. 2 is a schematic plan view of FIG. 10 …… Fixed guide ring (annular member), 11 …… Circumferential groove, 1
2, 13 ... Straight cam groove, 20 ... Straight cam ring (annular member), 23, 24 ... Complex curved cam groove, 30 ... Rotating cam ring (annular member), 31 ... Rear lens group frame (annular member) Member), 61,
71: roller, 61a, 71a ... insertion hole, 62, 72 ... fixing screw, 64, 65, 74 ... annular elastic part, 62a, 72a ... head part, 62
b, 72b ... neck part, 66,73 ... small diameter part, 67 ... deformation suppressing ring, L ... gap.

Claims (2)

[Scope of utility model registration request] 1. A lens barrel having a plurality of annular members fitted so as to be slidable relative to each other, a cam groove formed in one of the plurality of annular members, and a roller fitted in the cam groove fixed in the other. In the above, the roller is configured to be fixed to the annular member by a fixing screw that is inserted in a central portion thereof, and the roller is configured to have a diameter larger than the cam groove width in a state in which an external force is not applied, An annular elastic portion, the peripheral surface of which elastically abuts the cam groove when fitted into the cam groove, and which is located at least on the outer periphery of the head of the fixing screw; And a small diameter portion located on the outer circumference of the neck portion are integrally formed, and elastic deformation of the annular elastic portion is allowed between the outer circumference of the head portion of the fixing screw and the inner surface of the annular elastic portion, but an elastic limit is provided. Annular shape that suppresses elastic deformation beyond Fitting play prevention structure of the cam grooves and the roller in the relative sliding ring of the lens barrel, characterized in that a gap. 2. In the claim 1 of the utility model registration claim,
Two annular elastic portions are provided with the small diameter portion sandwiched therebetween, one of the two annular elastic portions is located on the outer periphery of the head of the fixing screw, and the other is provided on the opposite side of the head portion with the small diameter portion interposed. A deformation suppressing ring is provided on the neck of the fixing screw located on the outer periphery of the neck and corresponding to the inner surface of the other annular elastic portion, and between the inner surface of the other annular elastic portion and the deformation suppressing ring. In addition, an annular gap is formed which allows elastic deformation of the other annular elastic portion but suppresses elastic deformation exceeding the elastic limit.
A structure that prevents the play between the cam groove and the roller in the relative sliding ring of the lens barrel.