JP2535046Y2 - Lens barrel - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field] The present invention relates to a lens barrel having an annular member having a helicoid and a projection formed on a peripheral surface thereof.

"Prior art and its problems" A plurality of annular members are used for a lens barrel. In some of these annular members, a helicoid and projections for positioning, switching, and the like are provided together on the outer peripheral surface or the inner peripheral surface thereof. However, conventionally, the projection is provided independently of the helicoid, and therefore, the thickness of the annular member is increased. In other words, the thickness of the annular member needs to be added to the thickness of the helicoid in consideration of the thickness including the protrusion. However, the thickness of the annular member becomes a bottleneck for a lens barrel that is required to be reduced in diameter and size to the limit.

"Object of the invention" The purpose of the invention is to reduce the thickness of an annular member having a helicoid and a projection.

Another object of the present invention is to reduce the thickness of a cam ring, particularly as an annular member having such a helicoid and a projection.

"Outline of the invention" In the present invention, if a projection provided at a position different from the helicoid in the axial direction is provided on the extension of the helicoid mountain and within the contour of the mountain, the thickness for securing the projection is considered. He realized that the invention was not necessary and completed the present invention.

That is, the present invention provides a lens barrel having an annular member formed on the peripheral surface with a helicoid and a projection whose axial position is different from that of the helicoid. It is characterized by having been provided.

As the annular member and the projection, for example, a cam ring that moves a lens group by rotation along a helicoid, and a positioning projection of a code plate attached to an outer periphery of the cam ring to detect a rotation position of the cam ring can be assumed. .

Further, the protrusion may be a dog for turning on and off the switch member.

"Embodiments of the Invention" Hereinafter, the present invention will be described with reference to illustrated embodiments. In the illustrated embodiment, the present invention is applied to a cam ring 10 of a zoom lens barrel proposed by the present applicant in Japanese Patent Application No. 2-281116.

First, the overall structure of the zoom lens barrel will be described with reference to FIG. A helicoid ring 12 is fixed to a fixed lens barrel 11 integrated with the camera body, and a female helicoid 12a of the helicoid ring 12 is screwed with a male helicoid 10a formed on the outer peripheral surface of the cam ring 10. A female helicoid 10b and a cam groove (not shown) are formed inside the cam ring 10, and a male helicoid 13a of the front lens barrel 13 is screwed into the female helicoid 10b. At the rear end of the cam ring 10,
The rectilinear guide plate 14 is fixed, and a radial projection 14a of the rectilinear guide plate 14 is fitted in a rectilinear guide groove 11a formed in the fixed lens barrel 11. A straight guide ring 15 is fixed to the straight guide plate 14, and the cam ring 10 is rotatable with respect to the straight guide ring 15.

A block frame 13b to which the shutter block 16 is fixed is fixed to the front lens barrel 13.
A front group lens frame 18 holding a front group lens is screwed into a helicoid ring 17 provided integrally with the inner peripheral portion of the lens. The shutter block 16 has its drive pin 16a engaged with a driven pin 18a integrated with the front lens frame 18. Drive pin 16a
Is, as is well known, driven to rotate by an angle corresponding to the distance measurement signal from the distance measurement device.
The front lens group 18 (front lens group L1) is moved in the optical axis direction by the shutter block 16 while rotating, and focusing is performed.

The rear lens group frame 19 supporting the rear lens group L2 has a cam pin (not shown) projecting in the radial direction. The cam pin is formed on the inner surface of the cam ring 10 by the aforementioned cam groove (not shown). It is stuck in. The rear lens group frame 19 and the block frame 13b are guided in a straight line in the optical axis direction by a straight guide surface formed on the straight guide ring 15.

Therefore, in the zoom lens barrel having the above configuration, when the cam ring 10 is driven to rotate, the cam ring 10 itself moves in the optical axis direction according to the relationship between the male helicoid 10a and the female helicoid 12a. At the same time, the front lens barrel 13 (the front lens L1) moves straight in the optical axis direction due to the screwing relationship between the female helicoid 10b and the male helicoid 13a and the straight guide of the block frame 13b by the straight guide ring 15. When the cam ring 10 rotates, the relationship between a cam groove (not shown) on the inner surface of the cam ring 10 and a cam pin (not shown) provided on the rear group lens frame 19, and the straight movement of the rear group lens frame 19 by the straight guide ring 15 With the guide, the rear lens group frame 19 (the rear lens group L2) moves in the optical axis direction, and zooming is performed.

In the above-described zoom lens barrel, a code plate 20 is fixed to the outer periphery of the cam ring 10 as shown in FIGS. The code plate 20 comes into contact with a fixed brush (not shown) to detect the rotational position of the cam ring 10 and detect the focal length from the rotational position. For this reason, the relative position between the code plate 20 and the cam ring 10 needs to be exactly the same,
The cam ring 10 has a positioning hole 20a, and the cam ring 10 has a positioning projection 10c that fits into the positioning hole 20a. The code plate 20 is a drive gear formed on the outer periphery of the cam ring 10.
It is attached to the outer periphery of the cam ring 10 avoiding 10d.

The present invention is characterized in that the positioning projection 10c is provided on the extension line l of any one of the male helicoids 10a on the outer periphery of the cam ring 10 in a shape located within the contour of the mountain. When the positioning protrusion 10c is provided on the extension line l of the mountain of the male helicoid 10a and provided so as to be located within the contour of the mountain, the cam ring 10 rotates as is apparent in FIG. However, since the positioning projection 10c enters the valley of the female helicoid 12a of the partner, the male helicoid 10a and the female helicoid 1a
It does not prevent meshing with 2a. That is, since it is not necessary to consider the height of the projection 10c separately from the male helicoid 10a, the thickness of the cam ring 10 can be reduced.

FIGS. 5 and 6 show examples of the configuration of the cam ring 10 'when the positioning projection 10c' is provided independently of the male helicoid 10a. To prevent the positioning protrusion 10c 'from interfering with the engagement between the male helicoid 10a and the female helicoid 12a, the male helicoid 10a must be provided outside the positioning protrusion 10c'. Therefore, the thickness of the cam ring 10 'must be increased. This, on the contrary, shows that the thickness of the cam ring 10 can be reduced according to the present invention.

In the above embodiment, the male helicoid 10a is provided on the outer peripheral surface of the cam ring 10.
The present invention is applicable to a case where a helicoid and a projection are provided on the inner peripheral surface of the cam ring 10.

Although the present invention has been applied to the cam ring 10, the present invention is applicable to an annular member having a helicoid and a projection on the outer peripheral surface. The protrusion may be any protrusion such as a dog-like protrusion for turning on / off a switch such as a position detection switch or a limit switch, in addition to the above-described positioning of any member.

[Effects of the Invention] As described above, according to the present invention, the thickness of the annular member having the helicoid and the protrusion on the peripheral surface can be reduced, which contributes to the reduction in the diameter and size of the lens barrel. The protrusion is
When the annular member is a cam ring, it can be a positioning projection of a code plate for detecting its rotational position, or it can be a dog for turning on and off a switch member.

[Brief description of the drawings]

1 to 3 show an embodiment of a cam ring of a lens barrel according to the present invention. FIG. 1 is a perspective view, FIG. 2 is a development view, and FIG. FIG. FIG. 4 is a longitudinal sectional view of the lens barrel having the cam ring of FIGS. 1 to 3, in which the upper half shows a lens housed state and the lower half shows a lens protruding state (telescopic state). 5 and 6 are a perspective view and a sectional view showing a conventional cam ring. 10 ... Cam ring (annular member), 10a ... Male helicoid, 10b
…… Female helicoid, 10c …… Positioning protrusion (protrusion), 11
... fixed lens barrel, 11a ... straight guide groove, 12 ... helicoid ring, 12a ... female helicoid, 13 ... front group lens barrel, 13a ...
… Male helicoid, 13b …… Block frame, 14 …… Straight guide plate, 15 …… Straight guide ring, 16 …… Shutter block, 16a
… Driving pin, 17… Helicoid ring, 18… Front group lens frame, 18a… Driven pin, 19… Rear group lens frame, 20… Code plate, 20a… Positioning hole, l… Helicoid mountain Extension of.

Claims (3)

(57) [Scope of request for utility model registration] 1. A lens barrel having, on a peripheral surface thereof, an annular member having a helicoid and a projection whose axial position is different from that of the helicoid, wherein the projection is formed on an extension line of one of the helicoid peaks. A lens barrel characterized by being provided. 2. The lens barrel according to claim 1, wherein the annular member is a cam ring for moving the lens group by rotation along a helicoid, and the projection is a positioning projection of a code plate attached to an outer periphery of the cam ring. . 3. The lens barrel according to claim 1, wherein the projection is a dog for turning on and off a switch member.