JPH03119329A - Field variable finder device for camera - Google Patents

Abstract

PURPOSE:To miniaturize a camera although a cam mechanism is used by driving a finder by a finder driving ring where an optical axis is taken as the center of rotation. CONSTITUTION:The finder is driven by the finder driving ring 15 where the optical axis is taken as the center of rotation provided separately from a lens barrel cam ring 1 for changing a focal distance. Since the finder driving ring 15 rotates through a deceleration mechanism, the finder can be driven at a smaller rotation angle then that of the lens barrel cam ring 1. Therefore, a space for retreating a cam member which drives the finder is made small and the cam member can be retreated even in a part which has hitherto been regarded as dead space. Thus, the mechanism and the device for driving a finder optical system do not hinder the miniaturizing of a camera.

Description

[Detailed Description of the Invention] [Technical Field] The present invention relates to a variable field of view finder provided separately from a photographing optical system of a camera, which changes the field of view in conjunction with the photographing angle of view of a photographing optical system with a variable focal length. .

"Prior art and its problems" Zoom lens cameras (or multifocal cameras) that have separate photographic optical systems and finder optical systems generally perform zoom photography by rotating a lens barrel cam ring around the optical axis. The movable lens of the lens system is moved to change the focal length. Then, the movable lens of the finder optical system is moved in the optical axis direction in response to the rotation of this lens barrel cam ring, that is, the shooting conditions such as wide-angle, telephoto, macro, etc., and the field of view of the finder is secured according to the shooting angle of view. I have to.

The present applicant has developed a variable field of view finder of this type by protruding a driven pin from the frame of a plurality of movable lenses, fitting the driven pin into the cam groove of a flat cam provided in the finder body, and We have proposed and put into practical use a finder device in which the finder optical system is linked to the movement of the zoom lens system by moving it in conjunction with the rotation of the lens barrel cam ring.

However, because this planar cam moves horizontally at the top of the camera, the retraction space is quite large. ``Also, a device in which a movable lens is driven from the lower side by a disk cam or the like is known, but it has similar problems. For this reason, in the conventional device configuration, there has been a problem in that the space for the cam plate becomes an obstacle to miniaturizing the body of recent compact cameras in which a body as compact as possible is desired.

"Object of the Invention" The present invention was made in view of the above-mentioned conventional problems.
The present invention aims to provide a variable field of view finder device for a compact camera that can be miniaturized while using the same cam mechanism as the conventional one.

"Summary of the Invention" To achieve the above object, the present invention is based on the idea of using a finder drive ring whose rotation center is around the optical axis to drive the finder.

That is, the present invention provides a finder drive ring whose rotation center is the optical axis in addition to the lens barrel cam ring that changes the focal length of the photographic optical system, and decelerates the rotation of the lens barrel cam ring to change the viewfinder drive ring. The present invention is characterized in that a transmission reduction gear train is provided, and the two are interlocked so that the movable lens of the variable field of view finder device is moved by the rotation of this finder drive ring.

According to this configuration, the finder is driven by the finder drive ring that rotates around the optical axis, so space can be used effectively, and the finder drive ring is rotated separately from the lens barrel cam ring by a speed reduction mechanism. In particular, the finder can be driven at a rotation angle smaller than that of the lens barrel cam ring.

“Embodiments of the invention” Embodiments 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. 3 is a schematic sectional view showing the relationship between the lens barrel cam ring l and the finder drive ring 15. In Figure 1, 2 is a finder device;
3 is a strobe device.

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

A finder drive ring 15 is located on the outer periphery of the lens barrel cam ring 1 and is rotatable around the optical axis independently of the cam ring 1. A gear 16 is provided on the outer periphery of the finder drive ring 15, and the gear 16 and the lens barrel gear 4 mesh with each other via 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 the finder drive ring 1
Either a ring gear provided over the entire circumference of 5 or a sector gear provided partially may be used.

The finder device 2 includes first and second lenses 7.8 held movably in a direction parallel to the optical axis by a finder body (not shown), and a third lens 9 fixed to the finder body.
It is mainly composed of the fourth lens 10. Second lens 7
On the lower surfaces of the holder 11 and the holder 12 of the second lens 8, driven pins 13 and 14 are formed to protrude.

On the other hand, the finder drive ring 15 has a cam plate portion 17 having an arcuate cross section and projecting along the optical axis direction.

Two cam grooves 18 and 19 are formed in this cam plate part 17, and the driven pin 13 of the lunches 7 is inserted into the cam groove 19.
The driven pins 14 of the second lens 8 are fitted into the cam grooves 19, respectively. The contour shape of the cam grooves 18 and 19 is such that the positions of the first lens 7 and the second lens 8 can be varied so that the field of view of the finder device 2 corresponds to the wide-angle, telephoto, etc. shooting angle of view in the zoom shooting lens system. It is stipulated in

As mentioned above, the reduction gear train 20 includes gears 21.22.2.
3 and further has gears 24.25. This final gear 25 meshes with the strobe device 3.

That is, the strobe device 3 has a light emitting unit 26 movably held in a camera body (not shown) in a direction parallel to the optical axis. The light emitting unit 26 is a light emitting tube (xenon tube) 2
7 and a reflective umbrella, and a driven pin 2 on the bottom surface.
8 is formed in a protruding manner, and the driven pin 28 fits into a cam groove 30 provided in the strobe drive cam plate 29. Cam groove 30
The shape is determined so that the light emitting unit 26 is moved to a position where the irradiation angle of the strobe device 3 corresponds to the wide-angle, variable magnification, telephoto, etc. shooting angle of view in the zoom shooting lens system. The strobe drive cam plate 29 is a thin plate-shaped member extending in the horizontal direction perpendicular to the optical axis, and its finder drive ring 15
A rack 31 is formed on the lower surface of the side end. This rack 31 is engaged with the final gear 25. Further, the strobe drive cam plate 29 is provided with an elongated hole 32 in the same direction as the rack 31, and a guide pin 33 fitted into the elongated hole 32 restricts the direction of movement of the cam plate 29.

Next, the operation of this embodiment will be explained.

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 photographing lens system changes, allowing shooting modes such as wide-angle, telephoto, and macro. Realized. In the figure, W indicates wide-angle (WIDE), and T indicates telephoto (position E).

Also, when the lens barrel gear 4 rotates, the gear 2 of the reduction gear train 20
1 to 23, the finder drive ring 15 rotates at the same time. Then, the cam grooves 18 and 19 of the cam plate portion 17 of the drive ring 15 change their positions as the drive ring rotates.

For example, the lens barrel cam [1 is wide-angle (W) as shown by the arrow in the figure]
When the lens rotates from the wide-angle (W) position to the telephoto (T) direction, the cam plate portion 17 of the finder drive ring 15 rotates from the wide-angle (W) position to the telephoto (T) direction, like the lens barrel cam ring 1.

Then, the driven pin 13 of the second lens 8 and the driven pin 14 of the second lens 8, which are fitted into the cam grooves 18 and 19, move along the optical axis according to the shape of the cam grooves 18 and 19, respectively, and adjust the angle of view of the zoom lens. A corresponding finder field of view can be obtained.

During this operation, the finder drive ring 15 rotates independently of the lens barrel cam ring 1, and moreover, is rotated by a small angle than the lens barrel cam ring 1 by the reduction gear mechanism 20. Therefore, the moving distance of the cam plate portion 17 is small (and the retraction space thereof can be further reduced).

This effect will be explained in more detail with reference to FIGS. 4A and 4B. If the cam grooves 18.19 are formed in the lens barrel cam ring 1, the lens barrel cam ring 1 normally rotates over 180', so as shown in Figure 4B, the cam plate forming the cam grooves 18.19 The evacuation space TS' of 17゛ must also be made thicker accordingly, and the interval m between the spool chamber S and cartridge chamber P must be increased.On the other hand, in the present invention, the lens barrel cam ring 1 Since the cam grooves 18 and 19 are provided in the finder drive ring 15, which rotates at a slower speed than the cam grooves 18 and 19, the retraction space TS of the cam plate part 17 is small as shown in Fig. 4A, and the spool The distance m between the chamber S and the patrone chamber P can be reduced.

Further, the rotation of the lens barrel gear 4 is controlled by gears 21 to 2 of the reduction gear train 20.
5, and is also transmitted to the strobe drive cam plate 29 via the rack 31. As a result, the strobe drive cam plate 29 moves in the lateral direction perpendicular to the optical axis 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 perpendicular to the optical axis direction, and the light emitting unit 26 has its driven pin 28 pushed by the side surface of the cam groove 30, causing the cam to move. It moves along the optical axis according to the shape of the groove 30, and moves 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.
and the holder 11.12 of the second lens 8 each have a cam plate 40.41 on the lower surface, and a finder drive ring 1.
5 is provided with a pin base portion 42 in place of the cam plate portion 17.

Although this pin base portion 42 is smaller than the cam plate portion 17,
Similarly, it has an arcuate cross section. Cam plates 40, 41 provided on this holder 11, 12 are provided with cam grooves 45, 46, respectively. The shape of these cam grooves 45, 46 corresponds to the cam grooves 18, 19 of the first embodiment.

On the other hand, two drive pins 47 and 48 are formed in the pin stand part 42, one drive pin 47 is installed in the cam groove 45 of the cam plate 40 of the second lens 7, and the other drive pin 48 is installed in the second drive pin 48. It is designed to fit into the cam groove 46 of the cam plate 41 of the second lens 8.

Further, in the strobe device 3, a cam groove 43 is provided on the lower surface of the light emitting unit 26, and a cam plate 2 for driving the strobe
9 is replaced by a strobe drive lever 44. This cam groove 43 corresponds to the cam groove 30 provided in the strobe drive cam plate 29 in the second embodiment. A drive pin 49 is formed on the strobe drive lever 44 in place of the cam groove 30 in the previous embodiment, and is adapted to fit into the cam groove 43 of the light emitting unit 26.

This embodiment differs from the previous embodiment in that the pin is on the driving side and the cam groove is on the driven side, but the cam mechanism is composed of the pin and cam groove, and other configurations and operations are similar to those of the previous embodiment. It is similar to However, since the pin base portion 42 can be made smaller than the cam plate portion 17, there is an advantage that the retraction space thereof is smaller.

In the above embodiments, the variable focal length 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, in the present invention, the finder is driven by a finder drive ring that rotates around the optical axis, which is separate from the lens barrel cam ring that changes the focal length, and this finder drive ring has the following features: Since it rotates via a speed reduction mechanism, the finder can be driven at a smaller rotation angle than the lens barrel cam ring. Therefore, the retraction space for the cam member for driving the finder can be reduced, and the cam member can be retracted even in a portion that was conventionally considered a dead space.Therefore, the mechanism for driving the finder optical system, This has the effect that the device no longer becomes an obstacle to downsizing the camera.

Tropo device, 4... Lens barrel gear, 5... Zoom motor, 7... Second lens, 8... Second lens, 11.12
...Holder, 13.14...Followed pin, 15...
Finder drive ring, 17... cam plate part, 18.1
9... Cam groove, 20... Reduction gear train, 21-25.
... Gear, 26 ... Light emitting unit, 27 ... Strobe, 28 ... Followed pin, 29 ... Strobe drive cam plate, 30 ... Cam groove, 31 ... Rack, 40.41
...Cam plate, 42...Pin base part, 43...Cam groove, 44...Strobe drive lever, 45.46...
Cam groove, 47.48... Drive pin, 49... Drive pin, L... Optical axis.

[Brief explanation of drawings]

Fig. 1 is an exploded perspective view of the first embodiment of the present invention, Fig. 2 is an exploded perspective view of the second embodiment of the invention, and Fig. 3 shows the relationship between the lens barrel cam ring and the finder drive cam ring. Cross-sectional view, No. 4A,
Figure 4B is a schematic front view illustrating the invention in detail.

Claims (2)

[Claims] (1) A variable focal length photographing lens system that changes the focal length by rotating a lens barrel cam ring around the optical axis; has a movable lens and changes the field of view in conjunction with changes in the focal length of this photographic lens system. In a camera that has a variable field of view finder device separate from the photographic lens system that changes the field of view, a finder drive ring is provided that rotates around the optical axis, and the rotation of the lens barrel cam ring is decelerated to allow the viewfinder drive ring to 1. A variable field of view finder device for a camera, characterized in that a transmission reduction gear train is provided, and the movable lens of the variable field of view finder device is linked so that rotation of the finder drive ring moves the movable lens of the variable field of view finder device. (2) In claim 1, a cam groove is formed in either the finder drive ring or the movable lens holder,
The variable field of view finder device of the camera is provided with a driven pin that engages with this cam groove on the other side.