JPS6347865Y2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a variable focal length device for a camera that can change the focal length of a photographing optical system consisting of a main lens system and a sub lens system.

Cameras other than single-lens reflex cameras, especially 35mm lens shutter cameras, generally have a 35 to 40
Although a photographic lens with a focal length of mm is used, it is reasonable to use a lens with a focal length that matches the photographic angle of view depending on the conditions of the subject. Therefore, in order to create a camera that satisfies these functions, a sub-lens system is installed inside the camera in addition to the main lens system, and as the main lens moves, the sub-lens system moves in and out of the photographic optical axis as necessary. Various cameras have been devised that are capable of photographing at different focal lengths, such as standard photographing using only the main lens system and telephoto photographing using a combined optical system of the main lens system and the sub-lens system.

For example, FIG. 1 is a sectional view schematically showing the main parts of the conventional camera focal length variable device mentioned above.
indicates the standard shooting state, and B indicates the telephoto shooting state.

In the figure, in a lens barrel unit 10, a main lens system 1 is held in a main barrel 2 as a first photographing optical means, and a main barrel bar 3 parallel to the photographing optical axis is fixed to the main barrel 2. The lens system 4 is fitted into and held by the constituent members of the tube unit 10 at two places, and a sub-lens system 4 is held by an extender 5 as a second photographing optical means behind the main tube 2.
Similarly, it is rotatably supported around an extender bar 6 as a shaft member whose both ends are fitted and held in the constituent members of the lens barrel unit 10. An infinite adjustment screw 7 is screwed into the main barrel 2, and the tip of the infinite adjustment screw 7 is connected to a rotary ring 8 that fits into an intermediate component of the lens barrel unit 10 and is rotatable about the photographing optical axis. The main barrel 2 is biased by a coil spring 9 interposed between the main barrel 2 and the front surface of the lens barrel unit 10 so as to come into contact with the front cam section of the lens barrel unit 10. Therefore, when the rotating ring 8 is rotated by means not shown, the main cylinder 2
is controlled. A shutter device 11 is disposed between the main cylinder 2 and the extender 5.

Further, a support bar 12 is fixed to the rear component of the lens barrel unit 10 in parallel to the photographing optical axis, and the support bar 12 slides on one side of both the front and rear surfaces of a holding frame plate 13 fixed to the front surface of the camera body 15. A guide bar 14 is movably fitted and held, and has both ends fixed to the other side of the front and rear surfaces of the holding frame plate 13.
A lens barrel unit 10 is fitted into the lens barrel unit 10. Therefore, the lens barrel unit 10 is capable of sliding linearly in the front-rear direction of the camera together with the support bar 12 using the guide bar 14 as a guide. Lens barrel unit 10
A bellows 17 is disposed between the rear part of the camera body 15 and a light shielding plate 16 provided on the camera body 15 to form a dark box part. Note that 18 is a sprocket, and 19 is a camera exterior case.

In the conventional camera focal length variable device configured as described above, the so-called infinite focus adjustment in the standard shooting state shown in FIG. This is done by adjusting the screwing amount of the infinite adjustment screw 7, but when the lens barrel unit 10 is pulled out from the standard shooting state and the sub lens system 4 is rotated on the shooting optical axis,
When switching to the telephoto shooting state shown in Figure B, not only does the optical system consist of only the main lens system and the sub lens system, but also the shooting light of the main lens system and the sub lens system after the switching movement. Since it was difficult to set the position on the axis to the design value, there was a drawback that the infinity focus was shifted during telephoto shooting.

The present invention eliminates the drawbacks of the conventional example described above, and makes it possible to adjust the position on the photographing optical axis of the sub-lens system, which moves in and out of the photographing optical axis in conjunction with the movement of the main lens system in the direction of the photographing optical axis. It is an object of the present invention to provide a variable focal length device for a camera that can obtain proper focus in both standard photography and telephoto photography.

Hereinafter, embodiments of the present invention will be described based on the drawings.

FIG. 2 is a sectional view schematically showing the main parts of an embodiment of the camera focal length variable device according to the present invention;
indicates the standard shooting state, and B indicates the telephoto shooting state. However, the same components as those of the conventional example shown in FIG. 1 are given the same reference numerals, and the explanation thereof will be omitted, and only the differences will be explained.

In the figure, an extender bar 20, which is a shaft member serving as a rotating shaft to which an extender 5 holding a sub-lens system 4 as a second photographing optical means is fixed, is slidable in a direction parallel to the photographing optical axis. The lens barrel unit 10 is fitted and held at two locations: an intermediate component and a rear component. The extender 5 is biased toward the front of the camera by a coil spring 21 interposed between the extender 5 and the rear component of the lens barrel unit 10.
The front end of the extender bar 20 comes into contact with the tip of an adjustment screw 22, which is a second adjustment means screwed into the front component of the lens barrel unit 10, to restrict its movement in the front direction. Further, the extender 5 is rotatable around the extender bar 20, as in the conventional example shown in FIG.

Next, the focus adjustment operation of this embodiment with the above configuration will be explained.

First, infinite focus adjustment in standard shooting conditions is performed by adjusting the screwing amount of the infinite adjustment screw 7, which is the first adjustment means screwed into the main barrel 2, in the same way as described for the conventional example shown in FIG. This can be done by doing this.

Next, infinite focus adjustment in a telephoto shooting state can be performed by adjusting the screwing amount of the adjustment screw 22 screwed into the front component of the lens barrel unit 10. In other words, adjustment screw 2
When the screw-in amount of the extender bar 20 changes, the position of the extender bar 20, which is biased toward the front of the camera by the spring 21, changes in the front-rear direction of the camera.
Therefore, the position of the sub-lens system 4 of the extender 5 fixed to the extender bar 20 in the optical axis direction is adjusted, and infinite focusing is possible.

As explained above, the present invention provides a focal length variable device for a camera that changes the focal length by moving the second photographing optical means in and out of the photographing optical path. The second adjusting means for changing the shaft member in the axial direction displaces the second photographing optical means in the optical axis direction to achieve reference focus in a focal length state where the second photographing optical means enters the photographing optical path. Since the exposure adjustment is performed, the reference by the first adjustment means is made by displacing the first photographing optical means in the optical axis direction in a focal length state where the second photographing optical means is out of the photographing optical path. In addition to adjusting the focus, the second
This has the effect that the reference focusing can be easily and easily adjusted in a focal length state where the second photographing optical means is in the photographing optical path without causing the second photographing optical means to tilt or the like.

[Brief explanation of the drawing]

FIG. 1 is a cross-sectional view schematically showing the main parts of a conventional camera focal length variable device, in which A is a standard photographing state, B is a telephoto photographing state, and FIG. 2 is an embodiment according to the present invention. These are cross-sectional views schematically showing the main parts of the variable focal length device of the camera, where A is in a standard shooting state and B is in a standard shooting state.
is the telephoto shooting state. 1... Main lens system (first photographing optical means), 2
...Main barrel, 3...Main barrel bar, 4...Sub-lens system (second photographing optical means), 5...Extender,
7... Infinite adjustment screw (first adjustment means), 8...
Rotating ring, 9... Spring, 10... Lens barrel unit, 11... Shutter device, 12... Support bar,
13... Holding frame plate, 14... Guide bar, 15...
Camera body, 20... Extender bar (shaft member), 21... Spring, 22... Adjustment screw (second adjustment means).

Claims (1)

[Scope of utility model registration request] A first photographing optical means, a second photographing optical means, and a rotation shaft for holding the second photographing optical means and moving the second photographing optical means in and out of the photographing optical path to change the focal length. A first adjustment in which reference focusing is adjusted by displacing the first photographing optical means in the direction of the photographing optical axis with the shaft member forming the shaft member and the second photographing optical means exiting from the photographing optical path. and adjusting the reference focusing by displacing the second photographing optical means in the optical axis direction by displacing the shaft member in the axial direction while the second photographing optical means is in the photographing optical path. A variable focal length device for a camera, comprising: second adjustment means for adjusting the focal length of a camera.