JPH0342410Y2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a cylindrical cam coupling mechanism, and more particularly, to a cylindrical cam coupling mechanism used in, for example, a lens barrel of an interchangeable lens of a camera.

[Prior art] For example, the lens barrel of an interchangeable lens for a camera is
It consists of an inner cylinder that holds the lens and an outer cylinder that moves the inner cylinder, and these two cylinders are connected by a cam mechanism. A cam groove is formed in the outer cylinder, and a coupling shaft supporting a roller that fits into the cam groove is fixed to the outer surface of the inner cylinder to regulate the relative positions of the inner cylinder and the outer cylinder in the optical axis direction. There is. However, in such a cam coupling mechanism, the relative movement range of the two cylinders in the optical axis direction is limited by the length of the cam that can be formed in the optical axis direction of the outer cylinder. Unable to measure relative movement distance. In such cases, a cam groove may be formed in the inner cylinder and a coupling shaft supporting the rollers may be fixed to the outer cylinder.
In such a case, the arrangement of the inner and outer cylinders, rollers, and coupling shafts is as shown in FIG. 3 or 4, for example. The configuration shown in FIG. 3 above is
A female threaded portion 1a is formed from a proper position on the outer surface of the outer cylinder 1 having a thick cross section toward the central axis of the outer cylinder 1, and the outer surface of the outer cylinder 1 of this female threaded portion 1a is A recess 1b having a predetermined width and depth is formed. A cam groove 2a is formed on the outer surface of the inner cylinder 2 that fits into the outer cylinder 1. Above outer cylinder 1
A connecting shaft 8 having a male thread is screwed into the female threaded portion 1a of the cylinder, and the length of this connecting shaft 8 is equal to the thickness of each of the outer cylinder 1 and the inner cylinder 2. It is formed slightly shorter than the original, and its head is in the above-mentioned recess 1.
It is arranged to be located within b. The above coupling shaft 8
The lower half of the cam groove 2a has a cylindrical shape, and a roller 4 whose thickness is slightly thinner than the depth of the cam groove 2a is rotatably fitted in the lower half of the cylindrical shape. Further, this roller 4 is supported by the bottom 2b of the cam groove 2a of the inner cylinder 2 so as not to fall inside the inner cylinder 2 (downward in FIG. 3).

Further, in the configuration shown in FIG. 4, the inner cylinder 2 is connected to the third
It has the same structure as shown in the figure, and the outer cylinder 1A
and the coupling shaft 3 etc. are different. That is, a shallow square groove 1Aa having a rectangular planar shape is formed on the outer surface of the outer cylinder 1A, and a circular hole 1Ab extends from the center of the square groove 1Aa toward the central axis of the outer cylinder 1A.
is formed. Further, a fixing plate 5 having a rectangular planar shape is fitted into the square groove 1Aa, and the upper part of a thin cylindrical coupling shaft 3 is caulked to the center of the fixing plate 5. The coupling shaft 3 is adapted to fit into the circular hole 1Ab. Two circular holes are provided at predetermined positions on the fixing plate 5, and the upper surface of each of the circular holes is zigzag. A female thread is formed at the bottom of each of the square grooves 1Aa to which these circular holes correspond, and the fixing plate 5 is fitted into each groove 1Aa, and the connecting shaft 3
After fitting the roller 4 into the tip of the roller 4, the fixing plate 5 is attached to the outer cylinder 1A using fixing attachment screws 6 and 7.

In the conventional cylindrical cam coupling mechanism shown in FIGS. 3 and 4 configured as described above, the outer cylinders 1, 1A and the inner cylinder 2 are connected so that the roller 4 is connected to the cam groove 2.
Since the rollers 4 are rotatable, the outer cylinders 1,
1A and the inner cylinder 2 can move while restricting mutual movement.

[Problems to be Solved by the Invention] By the way, the conventional cylindrical cam coupling mechanism configured as described above has the following drawbacks. That is, the roller 4 is in the cam groove 2a of the inner cylinder 2.
The bottom of the cam groove prevents it from falling downward, so it cannot be used unless the cam groove has a bottom.
Therefore, processing costs are high when forming a cam groove with a bottom. Shakiness occurs because the roller 4 can move freely within the depth range of the cam groove 2 in the direction of the central axis of the coupling shaft 3 or 8. In addition, a tap portion for screwing the connecting shaft 8 or fixing screws 6, 7 is formed on the outer cylinder 1 or 1A, and the head of the connecting shaft 8 or the fixing plate 5 is connected to the outer cylinder 1.
Another problem is that the wall thickness of the force outer cylinder 1 becomes thick because the recess is provided so as not to protrude from the outer surface of the cylinder 1A.

This idea was devised by focusing on the above-mentioned drawbacks, and was designed to create a cylindrical cam coupling mechanism that requires fewer parts, requires less processing costs for cam grooves, and is easier to assemble. The purpose is to provide.

[Means and effects for solving the problem] In this cylindrical cam coupling mechanism, as shown in FIGS. 1 and 2, a cam hole 12a is formed in the circumferential surface of the inner cylinder 12, and A stepped screw 14 having a large-diameter roller receiving portion 14a on the head thereof is screwed together. The roller 13 rotatably attached to the stepped screw 14 is attached to the cam hole 12.
It is inserted into a.

With this structure, the roller 13 moves smoothly while rotating along the cam hole 12a.

[Example] Hereinafter, the present invention will be explained based on the illustrated example.

As shown in FIGS. 1 and 2, the inner cylinder 12, which is thin and long in the central axis direction, has a cam hole 12a having a predetermined width from near one end surface to near the other end surface.
For example, it is formed with a gentle slope.

On the other hand, the outer cylinder 11, which has a length of about 1/3 of the length of the inner cylinder 12 and is slidably fitted to the outer peripheral surface of the inner cylinder 12, has a At one point, a female threaded portion 11a is inserted toward the central axis of the outer cylinder 11.
is formed.

A stepped screw 14 screwed into this female threaded portion 11a
is an engaging portion 14d consisting of a large-diameter roller receiving portion 14a, a step portion 14b, a female screw portion 14c, and a slot.
It is formed to have. That is, the roller receiving portion 14a is connected to one end of the stepped screw 14 (the first
It is formed at the lower end in the figure, and its planar shape is circular and its diameter is slightly larger.
Above this roller receiving part 14a, a stepped part 14b consisting of a shaft part having a slightly smaller diameter than this receiving part 14a is formed, and its length is about half the thickness of the roller 13 described below. . A male screw portion 14c is formed above the step portion 14b, and the male screw portion 14c is slightly thinner than the step portion 14b. And the same threaded part 14c
The length of the outer cylinder 11 is slightly shorter than the wall thickness of the outer cylinder 11, and an engaging part 14d formed with a slot for inserting a flathead screwdriver, which will be described later, is formed on the end surface thereof.

Further, the roller 13 has a thickness slightly smaller than the sum of the lengths of the roller receiving portion 14a and the stepped portion 14b, and one end surface (lower end surface in the figure) of the roller 13 has the roller receiving portion 14a. A recess 13a having a diameter slightly larger than the diameter of the recess 13a is formed. That is, when the roller 13 is inserted into the stepped screw 14, the recess 13a fits into the roller receiving portion 14a of the screw 14, thereby preventing the roller 13 from falling downward. It is held rotatably. The outer shape of this roller 13 is the same as that of the cam hole 12.
The width of the hole 12a is slightly smaller than that of the hole 12a so that the hole 12a fits loosely into the hole 12a.

To assemble the cylindrical cam coupling mechanism of the present invention constructed in this way, first, the outer cylinder 11 is fitted into the inner cylinder 12, and the cam hole 12a of the inner cylinder 12 and the outer cylinder 1 are connected.
1 and the female screw portion 11a of No. 1. Next, the roller 13 is fitted into the stepped screw 14 in a predetermined direction in advance, and the stepped screw 14 with the roller 13 fitted is inserted into the cam hole 12 from the inside of the inner cylinder 12.
a, and lightly screw it into the female threaded portion 11a. Next, insert a flat head screwdriver into the female threaded portion 11a on the outside of the outer cylinder 11, and tighten the stepped screw 1.
Insert the tip of the driver into the engaging portion 14d of No. 4. Then, when the driver is rotated in a predetermined direction, the stepped screw 14 is screwed toward the outer surface of the outer cylinder 11. Further, when the driver is rotated, the stepped portion 14 of the stepped screw 14
b is engaged with the female threaded portion 11a of the outer cylinder 11, and is tightened and fixed. Note that even when tightened in this manner, the roller 13 remains rotatable.

With this configuration, roller 1
3. By rotating the outer cylinder 11 to which the stepped screw 14 is attached, the inner cylinder 12 can be rotated and moved in the central axis direction along the cam hole 12a.

In this embodiment, the case where the cam hole does not have a bottom has been described, but when a cam groove (that is, a cam with a bottom) is used, a cam groove with a bottom as shown in FIG. 2 at the appropriate position of 12c
A hole 12b into which the roller 13 can be inserted as shown by the dotted chain line is provided, and the stepped screw 14 having the roller 13 is inserted into the hole 12b.
All you have to do is tighten it.

[Effects of the invention] According to the invention, the number of parts is only two, a stepped screw and a roller, and assembly is easy, and processing costs can be reduced because a cam hole without a bottom can be used. I can do it.

[Brief explanation of the drawing]

Fig. 1 is an enlarged sectional view of the main parts of a cam cylinder coupling mechanism showing one embodiment of the present invention, and Fig. 2 is an exploded view of the cam barrel coupling mechanism of one embodiment of the present invention shown in Fig. 1 above. The perspective view and FIGS. 3 and 4 are enlarged sectional views of essential parts showing a conventional cam cylinder coupling mechanism. 1, 1A, 11...Outer cylinder, 11a...Female threaded part, 2, 12...Inner cylinder, 12a...Cam hole, 12
b...hole, 12c...cam groove, 13...roller,
14...Stepped screw.

Claims (1)

[Scope of Utility Model Registration Claim] A cam connection mechanism that regulates the relative position of two cylinders that are fitted into each other, comprising a cam slot formed in an inner cylinder, a roller that fits into the cam slot, and an outer cylinder. A female threaded portion provided on the tube passes through the center of the roller, a large diameter head provided at one end receives the roller, holds the roller within the cam slot, and the other end A cylindrical cam coupling mechanism characterized by comprising: a stepped screw for screwing the threaded part of the threaded part into the female threaded part;