JP2820158B2 - Variable viewfinder device for camera - Google Patents

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a field-of-view variable finder provided separately from an imaging optical system, which changes a field of view in conjunction with an imaging angle of view of an imaging optical system having a variable focal length of a camera. .

"Prior art and its problems" Generally, a zoom lens camera (or multifocal camera) having a photographing optical system and a finder optical system separately rotates a lens barrel cam ring about the optical axis as a zoom photographing lens system. Are moved to change the focal length. Then, the movable lens of the finder optical system is moved in the optical axis direction according to the rotation of the lens barrel cam ring, that is, the shooting state such as wide angle, telephoto, macro, etc., so as to secure the finder field of view according to the shooting angle of view. I have to.

The present applicant, as this kind of variable view finder, protrudes a driven pin from a frame of a plurality of movable lenses, fits the driven pin into a cam groove of a flat cam provided in a finder body, and A finder device in which the finder optical system is linked to the movement of the zoom lens system by moving the zoom lens system in association with the rotation of the lens barrel cam ring has been proposed and put into practical use.

However, since the flat cam moves laterally at the top of the camera, the evacuation space becomes considerably large. A device for driving the movable lens from below by a disk cam or the like is also known, but has a similar problem. For this reason, the conventional device configuration has a problem in recent compact cameras that require a compact body as much as possible, and the space for the cam plate is an obstacle to downsizing the body.

[Object of the Invention] The present invention has been made in view of the above-described conventional problems, and an object of the present invention is to provide a variable view finder device of a compact camera which can be reduced in size while using a cam mechanism as in the related art. .

[Summary of the Invention] In order to achieve the above object, the present invention provides a finder drive ring having a rotation axis about the optical axis of the photographing optical system, separately from a lens barrel cam ring for driving the photographing optical system. This is based on the idea of using.

That is, the present invention has a variable focal length photographing lens system that changes the focal length by rotating the lens barrel cam ring about the optical axis as a center of rotation, and at least one movable lens. In a camera having a field-of-view variable finder device different from the photographing lens system, the camera is provided so as to be rotatable independently of the lens barrel cam ring, separately from the lens barrel cam ring. A finder drive ring about the optical axis of the taking lens system as a center of rotation;
A reduction gear train for reducing the rotation of the lens barrel cam ring and transmitting the reduced rotation to the finder drive ring; and interlocking the two so that at least one movable lens of the variable view finder device is moved by the rotation of the finder drive ring. And an interlocking mechanism that causes the interlocking mechanism to be provided.

According to this configuration, the finder is driven by the finder drive ring centered on the optical axis of the photographing lens system, so that space can be effectively used. Further, the finder drive ring is separated from the lens barrel cam ring by the speed reduction mechanism. Therefore, the finder can be driven with a rotation angle smaller than the lens barrel cam ring.

Preferably, the interlocking mechanism includes a cam groove formed on one and the other of the holder supporting the at least one movable lens and the finder drive ring, and a driven pin engaged with the cam groove.

"Examples of the Invention" Examples of the present invention will be described below with reference to the drawings.

FIG. 1 is an exploded perspective view showing a first embodiment of the present invention, and FIG.
The figure is a schematic sectional view showing the relationship between the lens barrel cam ring 1 and the finder drive ring 15. In FIG. 1, 2 is a finder device,
3 is a flash device.

The constituent lens groups L1 to L3 of the zoom photographing lens system advance and retreat in the optical axis direction by rotating the lens barrel cam ring 1 rotatable around the optical axis. Various such mechanisms are well known.
The lens barrel cam ring 1 is integrally provided with a lens barrel gear 4 on its outer peripheral surface. The lens barrel gear 4 meshes with a zoom motor 5 via a reduction gear train 6.

A finder drive ring 15 is rotatably supported on the outer periphery of the lens barrel cam ring 1 so as to be rotatable around the optical axis of the taking lens system. The finder drive ring 15 is provided with a gear 16 on its outer periphery. The gear 16 and the lens barrel gear 4 mesh with each other via the gears 21, 22 and 23 of the reduction gear train 20. That is, the first gear 21 of the reduction gear train 20 meshes with the lens barrel gear 4, and the final gear 23 meshes with the gear 16. This gear 16 is fitted with a finder drive ring 15
May be either a ring gear provided over the entire circumference or a sector gear provided partially.

The finder device 2 includes first and second lenses 7 and 8 held on a finder body (not shown) so as to be movable in a direction parallel to the optical axis L of the photographing lens system, a third lens 9 and a fourth lens fixed on the finder body. It is mainly composed of a lens 10. Holder 11 for first lens 7 and holder for second lens 8
On the lower surface of 12, driven pins 13 and 14 are formed so as to protrude.

On the other hand, the finder drive ring 15 has a cam plate portion 17 having an arc-shaped cross section which is formed to protrude along the optical axis L direction. The cam plate 17 has two cam grooves 18 and 19 formed therein.
The driven pin 13 of the first lens 7 fits into the cam groove 19, and the driven pin 14 of the second lens 8 fits into the cam groove 19. The contour shapes of the cam grooves 18 and 19 change the positions of the first lens 7 and the second lens 8 to positions where the field of view of the finder device 2 corresponds to the shooting angle of view such as wide angle and telephoto in the zoom shooting lens system. It is defined as follows.

As described above, the reduction gear train 20 has the gears 21, 22, and 23, and further has the gears 24 and 25. This final gear 25 is engaged with the strobe device 3.

That is, the strobe device 3 is attached to a camera body (not shown)
The light emitting unit 26 is movably held in a direction parallel to the optical axis L. The light-emitting unit 26 has a light-emitting tube (xenon tube) 27 and a reflector, and a driven pin 28 projects from the lower surface thereof.
Is fitted in the cam groove 30 provided in the groove. The shape of the cam groove 30 is set so that the light emitting unit 26 is moved to a position corresponding to the irradiation angle of the strobe device 3 to a photographing angle of view such as wide angle, variable power, and telephoto in the zoom photographing lens system. The flash drive cam plate 29 is a thin plate extending in the horizontal direction perpendicular to the optical axis L, and a rack is provided on the lower surface of the end of the finder drive ring 15 side.
31 is formed. And this rack 31 is the last gear
Meshes with 25. Also, the strobe drive cam plate 29 has
An elongated hole 32 in the same direction as the rack 31 is provided, and the moving direction of the cam plate 29 is regulated by a guide pin 33 fitted in the elongated hole 32.

 Next, the operation of this embodiment will be described.

When the zoom motor 5 rotates, the lens barrel cam ring 1 rotates via the reduction gear train 6 and the lens barrel gear 4, and the focal length of the zoom lens system changes. Is achieved. In the figure, W indicates wide angle (WIDE), and T indicates telephoto (TELE).

When the lens barrel gear 4 rotates, the gear 21 of the reduction gear train 20 is rotated.
Through 23, the finder drive ring 15 rotates simultaneously. Then, the cam groove 18 of the cam plate portion 17 of the drive ring 15,
19 changes position with its rotation.

For example, if the lens barrel cam ring 1 rotates from the wide angle (W) position to the telephoto (T) direction as shown by the arrow in the figure,
The cam plate 17 of the finder drive ring 15 rotates from the wide-angle (W) position to the telephoto (T) direction, similarly to the lens barrel cam ring 1. Then, the driven pin 13 of the first lens 7 and the driven pin 14 of the second lens 8 fitted in the cam grooves 18 and 19 respectively become the cam grooves.
The lens moves along the optical axis L in accordance with the shapes of 18 and 19, and a finder visual field corresponding to the angle of view of the zoom lens is obtained.

In this operation, the finder drive ring 15 rotates independently of the lens barrel cam ring 1, and rotates by a smaller angle than the lens barrel cam ring 1 by the reduction gear mechanism 20. For this reason, the cam plate
The moving distance of 17 is small, and the evacuation space can be further reduced.

This effect will be described in more detail with reference to FIGS. 4A and 4B. If the cam grooves 18 and 19 are formed in the lens barrel cam ring 1, the lens barrel cam ring 1 normally rotates 180 ° or more, so that the cam plate portion forming the cam grooves 18 and 19 as shown in FIG. The 17 'evacuation space TS' must be enlarged accordingly.
The distance m 'between the spool chamber S and the cartridge chamber P must be increased. On the other hand, the present invention relates to the lens barrel cam ring 1.
Independently from the above, the cam grooves 18 and 19 are provided in the finder drive ring 15
As shown in the figure, the evacuation space TS of the cam plate 17 is small, and the distance m between the spool chamber S and the cartridge chamber P can be reduced.

The rotation of the barrel gear 4 is also transmitted to the flash drive cam plate 29 via the rack 31 via the gears 21 to 25 of the reduction gear train 20. As a result, the flash drive cam plate 29 moves in the horizontal direction orthogonal to the optical axis L direction. That is, the strobe drive cam plate 29
Also moves from the wide-angle (W) position to the telephoto (T) direction in a direction orthogonal to the optical axis L direction, and the light-emitting unit 26 has its driven pin 28 pushed by the side surface of the cam groove 30, according to the shape of the cam groove 30. To move in the direction of the optical axis L, and to a position where an irradiation angle corresponding to the angle of view of the zoom lens can be obtained.

FIG. 2 shows a second embodiment of the present invention. The holders 11 and 12 of the first lens 7 and the second lens 8 have cam plates 40 and 41 on the lower surface, respectively. A pin base section 42 is provided instead of the section 17. The pin base portion 42 is smaller than the cam plate portion 17, but similarly has an arc-shaped cross section. The cam plates 40, 41 provided on the holders 11, 12
Are provided with cam grooves 45 and 46, respectively. These cam grooves 45,
The shape of 46 corresponds to the cam grooves 18, 19 of the first embodiment. On the other hand, two driving pins 47 and 48 are formed on the pin base portion 42, and one driving pin 47 is provided in the cam groove 45 of the cam plate 40 of the first lens 7 and the other driving pin 48 is provided therein. The second lens 8 fits into the cam groove 46 of the cam plate 41.

In the strobe device 3, a cam groove 43 is provided on the lower surface of the light emitting unit 26, and a strobe driving lever 44 is provided in place of the strobe driving cam plate 29. This cam groove 43 corresponds to the cam groove 30 provided on the flash drive cam plate 29 in the first embodiment. A driving pin 49 is formed in the strobe driving lever 44 in place of the cam groove 30 in the previous embodiment, and the cam groove 43 of the light emitting unit 26 is formed.
It is designed to fit into.

This embodiment is different from the previous embodiment in that the pin is on the drive side and the cam groove is on the driven side, but the cam mechanism is constituted by the pin and the cam groove, and other configurations and operations are the same as those of the previous embodiment. Is the same as However, since the pin base portion 42 can be made smaller than the cam plate portion 17, there is an advantage that the evacuation space can be smaller.

In the above embodiment, the variable focus photographing lens system is described as a zoom lens, but the present invention is also applicable to a multifocal photographing lens.

[Effects of the Invention] As described above, according to the present invention, since the finder is driven by a finder driving ring centered on the optical axis of the photographing optical system, which is different from the lens barrel cam ring that changes the focal length, A large evacuation space like a flat cam is not required, and there is no need to secure an extra space around the finder device, so that the space inside the camera can be saved. Further, since the finder drive ring rotates via the speed reduction mechanism, the finder can be driven with a rotation angle smaller than the lens barrel cam ring. For this reason, the retreat space of the interlocking mechanism (cam plate portion or driven pin base portion) for driving the finder can be reduced, and the interlocking mechanism can be retreated only in a portion which was conventionally a dead space. Therefore, there is an effect that the mechanism and device for driving the finder optical system do not become an obstacle to downsizing of the camera.

[Brief description of the drawings]

FIG. 1 is an exploded perspective view of a first embodiment of the present invention, FIG. 2 is an exploded perspective view of a second embodiment of the present invention, and FIG. 3 shows a relationship between a lens barrel cam ring and a finder driving cam ring. Cross section, 4A, 4B
The figure is a schematic front view illustrating the effect of the present invention. DESCRIPTION OF SYMBOLS 1 ... Barrel cam ring 2 ... Finder device 3 ... Strobe device 4 ... Barrel gear 5 ... Zoom motor 7
... First lens, 8 ... Second lens, 11, 12 ... Holder,
13, 14 ... driven pin, 15 ... finder drive ring, 17
…… Cam plate part, 18, 19 …… Cam groove, 20 …… Reduction gear train,
21 to 25: gear, 26: light emitting unit, 27: strobe, 28: driven pin, 29: strobe drive cam plate, 30 ...
... Cam groove, 31 ... Rack, 40, 41 ... Cam plate, 42 ... Pin base, 43 ... Cam groove, 44 ... Strobe drive lever,
45, 46 ... cam groove, 47, 48 ... drive pin, 49 ... drive pin, L ... optical axis.

Claims (2)

(57) [Claims] A variable focal length photographing lens system for changing a focal length by rotating a lens barrel cam ring about an optical axis as a center of rotation; and at least one movable lens, wherein a focal length change of the photographing lens system is provided. In a camera having a field-of-view variable finder device different from the photographing lens system, the field of view is changed in conjunction with the camera lens system, provided separately from the lens barrel cam ring and rotatable independently of the lens barrel cam ring. A finder drive ring centered on the optical axis of the photographing lens system; a reduction gear train for reducing the rotation of the lens barrel cam ring and transmitting the rotation to the finder drive ring; A variable mechanism for interlocking at least one movable lens of the variable field of view finder device so as to move the movable lens. 2. A viewfinder device according to claim 1, wherein said interlocking mechanism comprises a cam groove formed on one and the other of a holder for supporting said at least one movable lens and a finder driving ring. A variable view finder device for a camera, comprising a driven pin engaged with a groove.