JPH0682670A - Zoom mechanism - Google Patents

Abstract

PURPOSE:To provide a zoom mechanism by which finder magnification can be specially made large and the degree of freedom as for optical design can be expanded. CONSTITUTION:At least two moving lens groups 1 and 16, 1c and 10 of a photographing lens system and a finder lens system which can be respectively moved in the optical axis direction in order to execute variable power, are provided. Then, the moving lens group 1 having large moving quantity out of the moving lens groups 1 and 16 of the photographing lens system and the moving lens group 10 having the large moving quantity out of the moving lens groups 1c and 10 of the finder lens system are interlocked with each other. Specially, they are interlocked with each other through a rotating member 13 having a rotational center between the optical axis of the finder system and the optical axis of the photographing system. By properly setting lever ratio on the rotating member 13, the finder magnification can be made large.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a zoom mechanism for a camera or the like, and more particularly to a zoom mechanism for a camera or the like having a viewfinder system optical axis different from the photographing system optical axis.

[0002]

2. Description of the Related Art Conventionally, in a zoom mechanism of a camera having a photographing system and a finder system, two zoom mechanisms are used.
The zooming operation is performed by moving the lens group of the group or more. As the moving method, for example, Japanese Patent Laid-Open No. 1-2
As described in Japanese Unexamined Patent Publication No. 24718, the moving lens groups of the photographing system and the finder system are configured to move by the same amount during zooming, or configured to move by a linear amount at a fixed rate. Things are known.

[0003]

However, in the above-mentioned conventional example, in the case of the zoom mechanism in which the moving lens groups are moved by the same amount, the moving lens groups of the finder system can move only by the moving amount of the photographing system variable magnification lens. Therefore, the viewfinder magnification cannot be increased. Also, in the case of a zoom mechanism in which the moving lens group moves by a linear amount, it is necessary to design the movement locus of the viewfinder zoom lens to be similar to that of the shooting lens. There are restrictions on the design of the finder optical system.

In view of the above situation, it is an object of the present invention to provide a zoom mechanism which can increase the viewfinder magnification and can increase the degree of freedom in optical design.

[0005]

The zoom mechanism of the present invention comprises:
Each of the shooting lens system and the viewfinder lens system
It has at least two moving lens groups that are movable in the optical axis direction for zooming, and includes a moving lens group having a large movement amount among the moving lens groups of the above-mentioned taking lens system and a moving lens group of the above-mentioned finder lens system. Of these, a moving lens group having a large amount of movement is linked.

Further, in particular, the moving lens group of the finder lens system having a large movement amount and the moving lens group of the photographing lens system having a large movement amount have a center of rotation between the finder system optical axis and the photographing system optical axis. It is configured to be interlocked via a rotating member.

Further, the moving lens group of the finder lens system having a large moving amount and the moving lens group of the photographing lens system having a large moving amount are configured to move non-linearly via the cam.

[0008]

According to the present invention, first, the moving lens group of the finder lens system having a large moving amount and the moving lens group of the photographing lens system having a large moving amount are interlocked with each other via the rotating member,
The finder magnification can be increased by appropriately setting the lever ratio of the rotating member.

Further, by interlocking with the moving lens groups of the finder lens system and the taking lens system, each of which has a large amount of movement, via the rotating member, the moving directions of the both lens groups are reversed by a simple and compact mechanism. Can be made.

Furthermore, by making the movement locus of the second lens group of the finder system non-linear through the cam, the degree of freedom in optical design can be increased.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the zoom mechanism of the present invention will be described below with reference to FIGS. FIG. 1 shows a main structure of a zoom mechanism of the present invention, and FIG. 2 is a sectional view thereof. In the figure, reference numeral 1 denotes a lens barrel that holds a first lens group of a photographing system. Guide portions 1a and 1b are formed on the side surface of the lens barrel 1 so that the lens barrel 1 is slidable by the screw shaft 2 and the guide bar 3 via the guide portions 1a and 1b. Guided. The screw shaft 2 is rotatably supported by the bases 4 and 5, and the pinion 6 and the cam 7 are attached so as to rotate integrally by a method such as press fitting. Further, 8 is a steel ball (Fig. 2), and this steel ball 8 is
A leaf spring 9 fixed to the lens barrel 1 side urges the screw portion 2 a formed on the screw shaft 2 so as to be pressed against the screw portion 2 a.

Reference numeral 1c is a first finder barrel for holding a finder system first lens group, which is formed integrally with the lens barrel 1. Reference numeral 10 is a second finder barrel for holding a second finder system lens group, and a groove 12 formed in the guide bar 11 and the base 12.
With a, it is guided so as to be movable in the optical axis direction.
The viewfinder relay lens group and the eyepiece lens group are not shown here. Reference numeral 13 is a lever, which is rotatably supported around a rotary shaft 14. A pin 1d formed on the lens barrel 1 is fitted in a groove 13a formed on one end side of the lever 13, and a pin 15 is planted on the other end side. The pin 15 is fitted in the cam groove portion 10 a formed in the second finder barrel 10.

Reference numeral 16 denotes a lens barrel for holding the second lens group of the photographing system, which is guided by the screw shaft 2 and the guide bar 3. Reference numeral 17 denotes a follower pin that is erected on the lens barrel 16 and is arranged so as to come into contact with the cam surface 7 a of the cam 7. Also, the compression coil spring 1
8 is elastically mounted between the lens barrel 16 and the stopper 19 arranged in the groove 2b of the screw shaft 2,
The compression coil spring 18 generates an urging force between them.

In the zoom mechanism constructed as described above, when the pinion 6 is driven, the screw shaft 2
Rotates, which causes the screw portion 2 of the screw shaft 2 to rotate.
The lens barrel 1 moves back and forth in the optical axis direction through the steel ball 8 according to the lead a. Due to the movement of the lens barrel 1, the lever 13 is rotated about the rotation shaft 14 as a fulcrum via the pin portion 1d, and further, the second finder barrel 10 is connected to the lens barrel 1 via the pin 15. Move in the opposite direction. Although the cam 7 rotates integrally with the screw shaft 2, the rotation of the cam 7 causes the lens barrel 16 urged by the compression coil spring 18 to follow the lift amount of the cam 7 via the follower pin 17. Move along the optical axis.

Here, FIG. 3 shows the operating relationship between the lever 13, the pin portion 1d and the pin 15. FIG. 3 (a) shows the respective positions at the so-called telescopic end.
Further, FIG. 3B shows respective positions at the wide end (Wide). The amount of movement of the second finder barrel 10 depends on the shape of the cam groove portion 10a and the rotation center (rotation shaft 14) of the lever 13 for each pin (pin portion 1d, pin 15).
And the lever ratio up to. FIG. 4 shows the relationship of the movement amounts of the second finder lens barrel 10 and the like. As is apparent from the figure, in the present embodiment, the first finder lens barrel 1c (that is, the lens barrel 1) moves linearly. On the other hand, the second finder barrel 10 moves non-linearly independently of the lens barrel 16.

In the above embodiment, an example of a lens optical system in which each of the taking lens system and the finder lens system has two moving lens groups has been described.
Even when the taking lens system and the finder lens system each include three or more moving lens groups,
It is possible to obtain the same effect as that of the above-mentioned embodiment.

[0017]

As described above, the link mechanism is used to link the finder system moving lens group having a large moving amount and the photographing system moving lens group having a large moving amount, thereby providing a simple and compact mechanism. It is possible to increase the finder magnification, and it is possible to increase the degree of freedom in the finder optical design by moving the finder system moving lens group non-linearly via a cam in the link mechanism.

[Brief description of drawings]

FIG. 1 is a diagram showing a configuration of a main part according to an embodiment of a zoom mechanism of the present invention.

FIG. 2 is a sectional view taken along line II-II of FIG. 1 in the main part of the zoom mechanism of the present invention.

FIG. 3 is a diagram showing an operational relationship between a lever, a pin portion, and a pin according to the zoom mechanism of the present invention.

FIG. 4 is a diagram showing a relationship between movement amounts of a first finder barrel and a second finder barrel according to the zoom mechanism of the present invention.

[Explanation of symbols]

 1 Lens barrel 1c 1st finder barrel 2 Screw shaft 3 Guide bar 6 Pinion 7 Cam 8 Steel ball 10 2nd finder barrel 11 Guide bar 13 Lever 14 Rotating shaft 15 Pin 16 Lens barrel 17 Follower pin 19 Stopper

Claims (3)

[Claims] 1. In a lens optical system having a variable magnification finder lens system in addition to a variable magnification photographing lens system, each of the photographing lens system and the finder lens system moves in the optical axis direction for variable magnification. There is at least two possible moving lens groups, and a moving lens group having a large moving amount among the moving lens groups of the above-mentioned taking lens system and a moving lens group having a large moving amount among the moving lens groups of the above mentioned finder lens system. A zoom mechanism characterized by being linked. 2. The rotating lens group of the finder lens system having a large moving amount and the moving lens group of the taking lens system having a large moving amount have a rotation center between the finder system optical axis and the photographing system optical axis. The zoom mechanism according to claim 1, wherein the zoom mechanism is configured to interlock with each other via a member. 3. The moving lens group of the finder lens system having a large moving amount and the moving lens group of the taking lens system having a large moving amount move non-linearly via a cam. Alternatively, the zoom mechanism according to claim 2.