JPH0762752B2 - Zoom lens camera - Google Patents

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a zoom lens camera, and more particularly to a zoom lens camera capable of accurately adjusting the magnification accuracy of a finder optical system to the magnification of a taking lens. Regarding

(Prior Art) VTR with lens shutter camera and optical viewfinder
In a camera or the like, when the taking lens is a zoom lens, it is necessary to change the magnification of the finder optical system so as to correspond to the magnification of the taking lens.

In a conventional zoom lens camera, a magnification conversion mechanism of a photographing lens and a magnification conversion mechanism of a finder are separately provided, and are linked by a lever or a link interposed between the two. However, in such an interlocking mechanism, the magnification of the finder image must linearly follow the magnification conversion of the photographic lens between tele and wide, but the magnification of the finder image matches that of the photographic lens. There was a problem that the accuracy was not good.

(Purpose) It is an object of the present invention to provide a zoom lens camera in which the magnification of a finder image is converted while being accurately matched to the magnification conversion of a taking lens between tele and wide.

(Structure) According to the present invention, a cam frame for moving at least two lens groups for changing the focal length of a photographing lens is used to change the magnification of a finder optical system corresponding to the change of the focal length of the photographing lens. It is characterized in that a cam groove for driving the objective lens of the finder is provided.

Embodiments of a zoom lens camera according to the present invention will be described below with reference to the drawings.

In FIGS. 1 and 2, a fixed ring 2 is fixed to the camera body 1, and a cam frame 3 is rotatably fitted around the fixed ring 2. The cam frame 3 includes cam grooves 3a and 3b for moving the front lens group and the rear lens group of the taking lens optical system in the optical axis direction, and the first objective lens and the second objective lens of the finder optical system. Cam grooves 3c and 3d for relative movement in the axial direction are formed. The front group moving frame 6 and the rear group moving frame 7 are provided on the inner peripheral side of the fixed ring 2.
Are fitted. The front group lens 4 is attached to the front group moving frame 6.
Rear group lenses 5 are fitted in the rear group moving frames 7, respectively.

A gear 9 is formed on the outer periphery of the rear end of the cam frame 3. The gear 8 is in mesh with the gear 9. The gear 8 is rotationally driven by a motor (not shown), and the motor is a telephoto unit provided on the camera body side.
A signal from the wide changeover switch is used to drive the rotation in the forward or reverse direction.

The front group moving frame 6 has a pin 10 and the rear group moving frame 7 has a pin 11 fixed thereto. As shown in FIG. 2, pin 10
Is fitted in the straight groove 2b provided in the fixed ring 2 in the optical axis direction and the cam groove 3a of the cam frame 3, and the pin 11 is provided between the straight groove 2a provided in the fixed ring 2 in the optical axis direction and the cam frame 3. It fits in the cam groove 3b. While the cam groove 3a intersects the rectilinear groove 2b in a circular arc, the cam groove 3b linearly intersects the rectilinear groove 2a at a constant angle.

A finder support plate 12 is fixed to the upper end side of the fixing ring 2, and a finder frame 13 is fixed to the finder support plate 12. An eyepiece lens is fixedly provided on the finder frame 13, and a first objective lens 14 and a second objective lens 15 are provided so as to be movable in the optical axis direction. The first objective lens 14 is integrally provided with a pin 14a, and the pin 14a is provided on the finder frame 13 with the linearly moving groove 13a in the optical axis direction and the cam frame 3.
It is fitted in the cam groove 3c. Similarly, the second objective lens 15 is integrally provided with a pin 15a, and the pin 15a is fitted in the straight groove 13a of the finder frame 13 and the cam groove 3d of the cam frame 3. The cam groove 3c and the cam groove 3d correspond to the movement of the front lens group 4 and the rear lens group 5 forming the photographic lens optical system in the optical axis direction, and the first objective lens 14 and the second objective lens of the finder optical system. A cam groove for moving 15 in the optical axis direction.

Next, the operation of the above embodiment will be described with reference to FIG.

When the zoom lens driving motor is rotationally driven by the operation of the tele / wide switching switch provided on the camera body side, the rotational force of the motor is applied via the gears 8 and 9 to the cam frame 3
And the cam frame 3 is rotationally driven around the optical axis.

Here, it is assumed that the cam frame 3 is rotationally driven by the angle θ from the wide side to the tele side. The rotation of the cam frame 3 causes the cam groove 3a to fix the pin 10 of the front group moving frame 6 to the fixing ring 2
Push along the straight groove 2b, and the amount of displacement of the cam groove 3a in the optical axis direction.
The front lens group 4 is moved in the optical axis direction by a distance corresponding to L2. Further, when the cam frame 3 rotates by the angle θ, the cam groove 3b pushes the pin 11 of the rear group moving frame 7 along the straight advance groove 2a of the fixed ring 2, and the displacement L1 of the cam groove 3b in the optical axis direction. The rear lens group 5 is moved in the optical axis direction by a distance commensurate with.
In this way, the front lens group 4 and the rear lens group 5 relatively move in the optical axis direction, whereby the focal length of the imaging lens is continuously converted.

By the rotation of the cam frame 3, the pin 14a of the first objective lens 14 of the finder is pushed by the cam groove 3c and moved in the optical axis direction, and the pin 15a of the second objective lens 15 moves in the cam groove 3c.
It is pushed by d and moved in the optical axis direction. The amount of movement of the first objective lens 14 and the second objective lens 15 in the optical axis direction is determined by the cam groove.
Displacement L3 in the optical axis direction of 3c and displacement of the cam groove 3d in the optical axis direction
Determined by L4. Since the displacement amounts L3 and L4 are set in correspondence with the movement amount of the front lens group 4 and the movement amount of the rear lens group 5, the magnification of the finder optical system corresponds to the magnification conversion of the taking lens optical system. Be converted.

As described above, according to the above-described embodiment, the finder image corresponding to the magnification of the subject image photographed by the photographing lens can be formed, so that the subject image can be accurately observed. Also, when changing the magnification by interlocking the viewfinder optical system with the magnification change of the taking optical system, instead of interlocking via a lever or link, a common cam frame is used to take the taking optical system by its cam groove. Since the viewfinder optical system is made to have a variable magnification, it has a feature that the configuration is simple and the size can be reduced.

The present invention can be applied not only to the range finder type camera but also to a VTR camera with an optical finder and a zoom lens. Further, the configuration of the taking lens optical system is not limited to the one shown in the illustrated embodiment, and for example, the present invention can be applied even when the number of lens groups that move during zooming is three or more.

(Effect of the Invention) According to the present invention, since the objective lens forming the finder optical system is also moved by using the cam frame for moving the lens group of the taking lens optical system in the optical axis direction,
The image magnification of the taking lens optical system and the image magnification of the finder optical system can be accurately and easily matched.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a sectional view showing an embodiment of a zoom lens camera according to the present invention, FIG. 2 is a development view showing a configuration of a cam groove portion of the same embodiment, and FIG. It is an operation explanatory view showing the relative movement relation between the taking lens and the viewfinder lens in the example. 3 …… Cam frame, 3a, 3b …… Cam groove for changing focal length of shooting lens, 3c, 3d …… Cam groove for moving finder lens, 1
4, 15 ... Finder objective lens.

Claims (1)

[Claims] 1. A cam frame driven by a zooming operation, and a cam groove formed in the cam frame for converting at least two lens groups in the optical axis direction to convert the focal length of a photographing lens. In the zoom lens camera having the above, the cam frame has a cam groove for driving the objective lens of the finder for changing the magnification of the finder optical system in accordance with the conversion of the focal length of the taking lens. Characteristic zoom lens camera.