JPH11337802A - Structure for holding finder variable power cam - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce the cost of a metallic mold and the cost of product by performing molding with a simple metallic mold constitution without making a structure complicated. SOLUTION: Both shaft parts 4a and 4b of this finder variable power cam 4 are born by the bearing part 7 of a baseplate 5 so as to be rotatable, and one bearing 7 is constituted of a bearing groove 7a which bears one of the shaft parts 4b of the cam 4 from an open part 7a2 in the radial direction, and an elastic member 9 which holds the shaft part 4b of the cam 4 by pressing the part 4b of the cam 4 against the bottom part 7a1 of the groove 7a.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a structure for holding a finder variable magnification cam in a zoom finder of various photographing devices, and more particularly, to at least one finder by rotation.
The present invention relates to a finder zoom cam holding structure for changing the image magnification by moving at least one lens in the optical axis direction.

[0002]

2. Description of the Related Art For example, a conventional finder variable magnification cam a shown in FIGS. 4 to 6 is held so as to be rotatable by a rotating shaft g which is carried by bearing holes c and d provided in front and rear of a base plate b. Have been. When the finder variable magnification cam a is driven to rotate, the lenses e, f, and the like are moved in the optical axis direction in accordance with the rotation direction and the amount of rotation to change the image magnification. Rotation axis g
Is inserted separately into the front and rear bearing holes c and d and the finder variable magnification cam a fitted between the bearing holes c and d so that the finder variable magnification cam is inserted between the front and rear bearing holes c and d. The cam a can be held. The rotating shaft g is pressed into one of the bearing holes c and d and is prevented from falling off.

As shown in FIGS. 4 and 5, a spring member h is mounted on the outer periphery of the finder variable magnification cam a so as to elastically hold it, and both ends h of the spring member h are mounted.
1 and h2 are turned outward and are closely opposed to the bottom surface b1 of the base plate b as shown in FIGS. The finder variable magnification cam a has a lens e,
f is moved inadvertently by the reaction force that moves f. However, regardless of the direction of this rotation, the bottom surface on which one of both ends h1 and h2 of the spring member h faces each other. By contacting b1, such return rotation is prevented. When the finder variable magnification cam a is driven to rotate, slippage occurs between the finder variable magnification cam a and the spring member h and does not hinder the rotation drive.

[0004]

However, if another rotary shaft g is used in combination to hold the finder variable power cam a so as to be rotatable as in the prior art, the number of parts and the number of assembly steps are reduced. The cost increases as the number increases. In addition, since the pair of bearing holes c and d are provided in the opposing walls j and k or the wall surfaces, the slide core that advances and retreats in a direction perpendicular to the separating and approaching direction of the mold is movable or fixed in some cases. The recesses k1 and k2 provided in the mold and in which the respective molds which are separated from and connected to each other communicate with each other as shown in FIG.
Therefore, it is necessary to use a structure in which the dies are engaged in a so-called cut-off state so as to form the above. In any case, since the structure of the mold becomes complicated, the cost of the mold increases, which causes an increase in product cost.

An object of the present invention is to provide a finder variable magnification cam holding structure which can be molded with a simple mold structure without complicating the structure, and which can reduce the cost of the mold and the product cost.

[0006]

SUMMARY OF THE INVENTION In order to achieve the above object, a finder variable magnification cam holding structure of the present invention changes an image magnification by moving at least one lens in the optical axis direction by rotation. In order to hold the finder variable power cam, the finder variable power cam is held so that the front and rear shafts are supported by the front and rear bearings of the base plate so as to be rotatable, and the one bearing is provided with the finder variable power cam. A bearing groove for receiving the shaft portion of the finder from an open portion in the radial direction, and an elastic member for elastically pressing and holding the shaft portion of the received finder variable magnification cam against the bottom of the bearing groove. Features.

As described above, one of the front and rear bearing portions for holding the front and rear shaft portions of the finder variable magnification cam so as to be rotatable on the base plate has a radially open bearing groove. Even if the other is a bearing hole, after fitting one of the front and rear shaft portions of the finder variable magnification cam into the bearing hole as the other bearing portion from the axial direction and bearing the other, the other of the front and rear shaft portions is the one of the one. By fitting into the bearing groove of the bearing part from the radial direction, the finder variable magnification cam located between the front and rear bearing parts is fitted to the front and rear bearing parts with its own front and rear shaft parts, and cooperates with the bearing grooves. The elastic member presses the shaft fitted into the bearing groove against the bottom of the bearing groove, so that the shaft can be stabilized in the bearing state, so that the finder variable magnification cam can be rotated with the same number of parts as the conventional one. Can be held in
Without complicating the structure, one of the bearings is a bearing groove that is open in the radial direction so that the mold can be pulled out and the mold structure can be simplified. Reduce. Moreover, the elastic member provides a brake for preventing an inadvertent return rotation caused by a reaction force for moving the lens of the finder variable magnification cam by friction when the shaft of the finder variable magnification cam is pressed against the bottom of the bearing groove. Including the braking of the finder variable magnification cam, the number of parts and the number of assembling steps are reduced as compared with the conventional one, and the product cost can be reduced in this aspect as well.

[0008] Further objects and features of the present invention will become apparent from the following detailed description and drawings. Each feature of the present invention can be used alone or in combination in various combinations as far as possible.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS One representative embodiment of the present invention will be described below together with its embodiment with reference to FIGS. 1 to 3 for the understanding of the present invention.

The structure for holding the finder variable magnification cam according to the present embodiment is an example when applied to a zoom finder of a still camera. However, the present invention is not limited to still cameras, but can be applied to general photographing devices including various cameras.

As shown in FIGS. 1 to 3, the structure for holding the finder variable magnification cam according to this embodiment rotates at least one lens, in the illustrated embodiment, two lenses 1 and 2 by the optical axis. The shaft portions 4 at both ends of the finder variable magnification cam 4 are rotatably supported and held by the finder variable magnification cam 4 which is moved in the direction of 3 to change the image magnification.
The bearings a and 4b are rotatably supported by bearings 6 and 7 of the base plate 5. In other words, the finder variable magnification cam 4 is supported and held so as to be rotatable without using a rotating shaft separate from the finder variable magnification cam 4. For this reason, in the present embodiment, one of the bearing portions, for example, the rear bearing portion 7 in the illustrated example is used.
As shown in FIGS. 1 and 2 (a) and 2 (b), the shaft portion 4b on the corresponding side of the finder variable magnification cam 4 is opened radially.
FIG. 3B is a view in which the bearing groove 7a received from the a2 and the shaft portion 4b of the received finder variable magnification cam 4 are urged and held as shown by an arrow F in FIG. 1, an elastic member 9 as shown in FIG. 2 (a) and FIG. 3 (b).

As shown in FIGS. 1, 2A, and 3A, the finder variable magnification cam 4 is a passive gear to which a driving force to be rotationally driven in accordance with a magnification operation is transmitted. 8
Are integrally provided on the outer periphery of the end having the shaft portion 4a on which the elastic member 9 does not work. As shown in FIGS. 2A and 3A, each of the lenses 1 and 2 is placed in a box portion 5a of a base plate 5 molded into a form as shown in FIG. 1 and 3 (a) which are accommodated and provided on the lower left and right sides of the optical axis 3.
A slider 1a as shown in FIG. 3A, which is individually supported and guided so that it can slide in the direction of the optical axis 3 by each of the guide shafts 11 and 12 as shown in FIG.
2a.

The guide shafts 11 and 12 are shown in FIGS.
As shown in the figure, the front wall 5b on which the finder window 5e on the object side of the box portion 5a is formed and the finder window 5 on the eyepiece side.
As shown in FIG. 2 (a) and FIG. 3 (a), when the sliders 1a, 2a are provided between the rear wall 5c having the f. Since the projections 1b and 2b provided on a part of the lenses 1 and 2 are guided in the direction of the optical axis 3 by the guide grooves 5d provided on the ceiling wall of the box portion 5a, the lenses 1 and 2 are It can be moved stably in the direction of.

The lenses 1 and 2 have cam followers 13 and 14 projecting radially from the sliders 1a and 2a as shown in FIG. 3A, and these cam followers 13 and 14 are shown in FIG. 2A. Peripheral cams 4 provided before and after the finder variable magnification cam 4 by means of a spring 15 which is appropriately actuated so as to urge them between the lenses 1 and 2 in a direction to approach them.
C and 4d are pressed against each other as shown in FIG.

With the above construction, the cam followers 13, 14 and the slider 1
The zoom finder optical system 16 is configured such that the lenses 1 and 2 are moved in the direction of the optical axis 3 following the lenses a and 2a.

However, such a zoom finder optical system 16 is not limited to the structure of the above-described embodiment as shown and described above. The present invention can be applied to any type in which the image magnification is changed by moving in the direction.

As described above, one of the bearings 6, 7 for holding the both shafts 4 a, 4 b of the finder variable magnification cam 4 so as to be rotatable on the base plate 5 is provided on the rear wall of the base plate 5. 5c has a bearing groove 7a which is radially opened to a part of the periphery of the finder 5c, and receives a shaft part 4b on the corresponding side of the finder variable magnification cam 4 from an opening part 7a2 of a part of the periphery thereof. However, even in the case of the bearing hole 6a as in the illustrated embodiment, one shaft portion 4a of the finder variable magnification cam 4 is connected to the bearing hole 6a by the axis 1
7, and then the other end 4b is fitted into the bearing groove 7a from the radial direction.
The finder variable magnification cam 4 is located between the front and rear bearings 6 and 7 and the finder variable magnification cam 4 is connected to the front and rear shaft portions 4.
a and 4b are fitted to the front and rear bearing portions 6 and 7, and the bearing groove 7
By pressing the shaft 4b fitted into the bearing groove 7a against the bottom 7a1 of the bearing groove 7a, the shaft 4b is stabilized in a bearing state by the elastic member 9 cooperating with the shaft a.

Accordingly, the finder variable magnification cam 4 can be supported and held so as to be rotatable with the same number of parts as the conventional one, and one of the bearing portions 6 and 7 has a diameter which is not particularly complicated. Since the bearing groove 7a is opened in the direction, the mold can be pulled out, and the cost of the mold and the product cost can be reduced as much as the mold structure can be simplified. Moreover, the elastic member 9 is connected to the shaft portion 4b of the finder variable magnification cam 4.
Can be applied to the finder variable magnification cam 4 by friction when pressing the finder against the bottom portion 7a1 of the bearing groove 7a. The number of parts and the number of assembling steps are reduced as compared with the conventional case, and the product cost can be reduced in this aspect as well.

In the embodiment shown in FIGS.
Uses a spiral spring type as shown in FIG.
For the urging, the spiral part 9a of the elastic member 9 is fitted to the outer periphery of the end on the side where the shaft part 4b of the finder variable magnification cam 4 is provided, and one end 9b extending from the spiral part 9a is connected to one end. The other end 9c is hooked on the other guide shaft 12 while being hooked on the guide shaft 11.

As shown in FIG. 3B, each end 9b, 9c of the elastic member 9 has a pair of guide shafts 1 as shown in FIG.
The reaction force F of the forces F1 and F2 that work to spread between 1 and 12
By the resultant force F of F3 and F4, the wrapping portion 9a is pressed against the outer periphery of the end of the finder variable magnification cam 4 in the direction of arrow F to act to press the shaft portion 4b against the bottom of the bearing groove 6a.

At this time, the finder variable magnification cam 4 is driven to rotate by the braking force generated by frictional resistance in a state where the inner periphery of the wrapping portion 9a is pressed against the outer periphery of the end of the finder variable magnification cam 4, and the spring 15 is rotated. If the lenses 1 and 2 are moved in the direction of the optical axis 3 and the lens 1 and 2 are inadvertently returned and rotated by the reaction force, they are braked and the finder variable magnification cam 4 is prevented from being returned and rotated. .

In addition, as shown in FIGS. 1 and 2, a portion 9a1 where the wrap portion 9a is in pressure contact with the outer periphery of the end of the finder variable magnification cam 4 has a larger number of turns of the wire than the other portions. By doing so, the frictional force increases more than other portions come into contact with the outer periphery of the end portion of the finder variable magnification cam 4, which is suitable for preventing the return rotation. The degree of braking for preventing the return rotation can be variously adjusted by changing the magnitude of the elastic restoring force of the elastic member 9 and the number of windings of the vine 9a. However, the elastic member 9 may be such that the leaf spring is pressed against the outer periphery such as the end of the finder variable magnification cam 4 or the like, and the form to be used and the method of acting on the finder variable magnification cam 4 are not particularly limited. Absent.

One end of each of the pair of guide shafts 11 and 12 is axially fitted into a mounting hole 21 of the front wall 5b as shown in FIG. 1, while the other end is formed to extend from the finder window 5f on the eyepiece side. The configuration in which the groove 22 is fitted in the groove 22 in the radial direction allows the mold to be formed together with the finder window 5f without any special process or mold operation. In addition, both ends 9b and 9c of the elastic member 9 are pressed against the guide shafts 11 and 12, so that both the guide shafts 11 and 12 are pressed against the bottom 22a of the groove 22 and stabilized.
No special member for holding the guide shafts 11 and 12 in the groove 22 is required. However, even if the guide shafts 11 and 12 are held by mounting holes instead of the grooves 22, they can be inserted and mounted in the axial direction.

[0024]

According to the finder variable magnification cam holding structure of the present invention, the finder variable magnification cam can be held so as to be rotatable with the same number of parts as the conventional one, and the structure is not particularly complicated. Since one of the bearing portions is a bearing groove that is opened in the radial direction, the mold can be pulled out, and the cost of the mold and the product cost can be reduced by the amount of simplification of the mold structure.

Furthermore, if the steps up to braking of the finder variable magnification cam are included, the number of parts and the number of assembling steps are reduced as compared with the conventional one, and the product cost can be reduced in this respect as well.

[Brief description of the drawings]

FIG. 1 is an exploded perspective view showing one example of a finder variable magnification cam holding structure according to a typical embodiment of the present invention.

2A and 2B show a holding structure of FIG. 1, wherein FIG. 2A is an exploded longitudinal sectional view in the optical axis direction, and FIG. 2B is a front view of a bearing groove.

3A and 3B show the holding structure shown in FIG. 1, in which FIG. 3A is a cross-sectional view in a direction perpendicular to the optical axis direction, and FIG. 3B is a view showing a bearing structure and a braking portion characteristic of a finder variable magnification cam; It is sectional drawing in the direction orthogonal to the optical axis direction.

FIG. 4 is an exploded perspective view showing a conventional finder variable magnification cam holding structure.

5 is a cross-sectional view showing a braking unit of the finder variable magnification cam shown in FIG. 4 in a direction perpendicular to the optical axis.

6 is an exploded cross-sectional view of the holding structure of the finder variable magnification cam shown in FIG. 4 in the optical axis direction.

[Explanation of symbols]

 1, 2 Lens 1a, 2a Slider 1b, 2b Projection 3 Optical axis 4 Finder zooming cam 4a, 4b Shaft 4c, 4d Peripheral cam 5 Base plate 5a Box 5b Front wall 5c Rear wall 5d Guide groove 6, 7 Bearing part 6a Bearing hole 7a Bearing groove 7a1 Bottom part 7a2 Open part 8 Passive gear 9 Elastic member 9a Vent part 9b, 9c End part 11, 12 Guide shaft 13, 14 Cam follower 15 Spring 16 Zoom finder optical system

Claims (2)

[Claims] 1. A finder variable magnification cam holding structure for changing at least one lens in an optical axis direction by rotation to change an image magnification, wherein the finder variable magnification cam has a front and rear shaft portion as a base plate. The bearing is held by the front and rear bearing portions so as to be rotatable, and the one bearing has a bearing groove for receiving the shaft portion of the finder variable magnification cam from a radially open portion, and the received finder variable magnification cam. And a resilient member for elastically pressing and holding the shaft portion against the bottom of the bearing groove. 2. The finder zoom cam holding structure according to claim 1, wherein the elastic member applies a friction braking force to the finder zoom cam by pressing against the shaft portion.