JPH0342411Y2 - - Google Patents

Description

[Detailed description of the invention] [Industrial application field] The present invention relates to a zoom lens barrel, and in particular, the present invention relates to a zoom lens barrel, and in particular, a fixed barrel having a slot extending in the optical axis direction, and a cam groove on the outer periphery of the fixed barrel. A cam barrel that fits into the fixed barrel, and a plurality of lens group drive frames that fit into the fixed barrel and have cam engaging portions that penetrate the slots of the fixed barrel and engage with the cam grooves of the cam barrel. The present invention relates to a zoom lens barrel equipped with a zoom lens barrel. Note that the slot in the fixed barrel is normally a straight slot parallel to the optical axis, but in order to use it for correcting the aperture aperture due to zooming, it has a slight component in the direction around the optical axis. In some cases, it is given, and "extending long in the optical axis direction" includes such cases.

[Prior art]

In the conventional zoom lens barrel as described above, when the zoom ring is rotated around the optical axis, the cam barrel rotates as a unit around the optical axis, and the plurality of lens group drive frames move each of the cam barrels. It was like being moved forward and backward in the optical axis direction by the cam groove and the slot in the fixed cylinder. That is, the cam engaging portion of the lens group drive frame also engaged with the slot of the fixed cylinder and was guided in the optical axis direction. Therefore, in order to prevent the lens group drive frame and the variable magnification movable lens driven by the lens group drive frame from wobbling around the optical axis, the slot in the fixed barrel is also engaged with the cam of the lens group drive frame. It was necessary to create highly accurate parallel slots with no engagement play.

On the other hand, in recent years, various parts of zoom lens barrels have been made of resin in order to reduce manufacturing costs and weight. If the fixed barrel of the zoom lens barrel as described above could also be made of resin, it would be possible to significantly reduce manufacturing costs and weight. However, when the fixed tube is integrally molded with resin, the width of the slot tends to become narrower at the center of its length, as shown by the dotted line in Figure 1, making it difficult to mold the slot to a uniform groove width. However, machining is required afterwards in order to create a uniform groove width with no engagement play with the cam engaging portion of the lens group drive frame. This is a major reason why the fixed cylinder is not made of resin.

(Purpose of the invention) The present invention was made to solve the above-mentioned reason why the fixed cylinder is not made of resin. The object of this invention is to provide a zoom lens barrel in which the lens is guided in the optical axis direction without wobbling around the optical axis.

[Structure of the idea]

The present invention provides a fixed barrel having a slot extending in the optical axis direction, a cam barrel having a cam groove and fitting onto the outer periphery of the fixed barrel, and a cam barrel that passes through the slot of the fixed barrel. a plurality of lens group drive frames having cam engaging portions that engage with cam grooves and fitting into the fixed barrel; and by rotating the cam barrel around the optical axis, In a zoom lens barrel in which the lens group drive frame moves forward and backward in the optical axis direction, the slot of the fixed barrel is formed into a relief groove with a groove width large enough for the cam engagement portion of the lens group drive frame to pass through. , a bottomed groove or a protrusion that separately extends in parallel to the slot in the fixed cylinder, and a bottomed groove or protrusion that engages with the bottomed groove or protrusion of the fixed cylinder in the lens group drive frame separately from the cam engagement part. The present invention provides a zoom lens barrel characterized by being provided with an engaging protrusion or groove, and with this configuration, the above object is achieved.

[Example] Hereinafter, the present invention will be explained using examples shown in FIGS. 2 to 5.

FIG. 2 is a sectional view showing an example of the zoom lens barrel of the present invention, FIGS. 3 and 4 are partial perspective views showing the engagement structure of the cam barrel, fixed barrel, and lens group drive frame, and FIG.
The figure is a graph of displacement in the optical axis direction of the variable magnification movable lens.

In the figure, 1 is a fixed barrel, 2 is a cam barrel, 3 is a zoom ring integrally connected to the cam barrel 2, and 4 and 5 are cam pins 6 and 7, which are cam engaging parts, respectively.
These are lens group drive frames in which lens group drive frames 4 and 5 are fitted in a fixed barrel 1, and a cam barrel 2 with a zoom ring 3 attached to the outer periphery of the fixed barrel 1 is fitted. After installing the cam pins 6 and 7 into the lens group drive frames 4 and 5 through the cam grooves 2a and 2b of the cam barrel 2 and the slots 1a and 1b of the fixed barrel 1, respectively, the cam barrel 2 is inserted into the fixed barrel 1. It is assembled by integrally attaching a fixed cylinder outer body 8 for preventing the cylinder from coming off. The lens group drive frame 4 drives the lens groups by screwing a lens holding frame 9 holding a lens group for both focusing and magnification into a helicoid screw 4a provided therein. Reference numeral 10 denotes a focus ring integrally connected to the lens holding frame 9 for moving the lens group in the optical axis direction using a helicoid screw for focusing. The lens group drive frame 5 directly holds and drives the second variable power lens group. Note that 11 is a diaphragm device held in the lens group driving frame 5, 12 is an index ring fitted into the fixed barrel 1, and 13 is a mount provided integrally with the fixed barrel 1.

In the conventional zoom lens barrel, the cam pins 6 and 7 of the lens group drive frames 4 and 5 engage with the cam grooves 2a and 2b of the cam barrel 2, and also engage with the slots 1a and 1b of the fixed barrel 1. However, in the zoom lens barrel of the present invention, the slots 1a of the fixed barrel 1,
1b has a groove width with a sufficient margin for the outer diameter of the cam pins 6, 7, and the cam pins 6, 7 are simply passed through, instead of the groove holes 1a, 1b and the cam pins 6, 7 not being engaged. , as shown in FIGS. 3 and 4, bottomed grooves 1c and 1d are provided on the inner surface of the fixed barrel 1 and extend parallel to the slots 1a and 1b, respectively, and the lens group driving grooves 1c and 1d are provided in the bottomed grooves 1c and 1d. Frame 4,
The engaging protrusions 4c and 5d provided on the respective parts 5 are engaged with each other. That is, the lens group drive frames 4 and 5 have engaging protrusions 4c and 5d that are connected to the fixed barrel 1, respectively.
By engaging with the bottomed grooves 1c and 1d, it is possible to prevent rattling around the optical axis.

In the zoom lens barrel of the present invention configured as described above, when the fixed barrel 1 is integrally molded with resin, the groove widths of the slots 1a and 1b are deformed as shown by dotted lines in FIG. Also, there is still enough cam pin 6,
There is room for 7 to pass through, and the bottomed grooves 1c and 1d
Because they have bottoms, they are less likely to deform and maintain sufficient engagement accuracy with the engagement protrusions 4c, 5d of the lens group drive frames 4, 5. Therefore, the fixed cylinder 1 can be easily made into an integrally molded product of resin material.

The illustrated zoom lens barrel has a zoom ring 3
By rotating the cam tube 2 around the optical axis,
rotates together, and the cam pin 6 is rotated by the cam groove 2a.
The lens group driving frame 4 having a cam pin 7 and the lens group driving frame 5 having a cam pin 7 are moved in the optical axis direction by the cam groove 2b, respectively, and the lens group is moved to a telephoto, wide-angle or intermediate position as shown in FIG. By rotating the focus ring 10 around the optical axis, the integrated lens holding frame 9 moves forward and backward in the optical axis direction using a helicoid screw, and only the lens group is integrated. It moves to adjust the focus.

The zoom lens barrel of the present invention is not limited to the illustrated example, but can also be used, for example, with more than two lens group drive frames, or where a plurality of lens group drive frames share a slot or a bottomed groove. But that's fine. Further, according to the present invention, as described above, it is easy to use an integrally molded product of resin material for the fixed tube, but the present invention is not necessarily limited thereto. Of course, the lens group drive frame and other parts may be integrally molded from a resin material. Furthermore, in the illustrated example, the fixed barrel is provided with a bottomed groove and the lens group drive frame is provided with an engaging protrusion, but by reversing this, a protrusion is provided on the fixed barrel and an engaging groove is provided on the lens group holding frame. It may be provided.

[Effect of idea]

In the zoom lens barrel of the present invention, the variable magnification movable lens group is guided in the optical axis direction without wobbling around the optical axis by the bottomed groove of the fixed barrel.
The groove width of the slot in the fixed tube through which the cam engaging portion of the lens group drive frame that engages with the cam groove of the cam tube passes can be increased, and it is possible to use an integrally molded product of resin material for the fixed tube. This has the effect of making it easier. In addition, since a large number of bottomed grooves can be provided in the fixed barrel regardless of the number of cam grooves in the cam barrel, the durability against wobbling of the variable magnification movable lens group around the optical axis can be increased. Therefore, the present invention is not limited to the fixed tube being an integrally molded product made of resin material.

[Brief explanation of drawings]

Figure 1 is a partial surface view of the fixed tube showing how the slot width changes when the fixed tube is integrally molded with resin;
FIG. 2 is a sectional view showing an example of the zoom lens barrel of the present invention, FIGS. 3 and 4 are partial perspective views showing the engagement structure of the cam barrel, fixed barrel, and lens group drive frame, and FIG. 5 is a modified version of the zoom lens barrel. It is a displacement graph of the magnification movable lens in the optical axis direction. 1...Fixed cylinder, 1a, 1b...Slot hole, 1c, 1
d...Bottomed groove, 2...Cam tube, 2a, 2b...Cam groove, 3...Zoom ring, 4, 5...Lens group drive frame, 4a...Helicoid screw, 4c, 5d...
...Engaging protrusion, 6, 7...Cam pin, 9...Lens holding frame, 10...Focus ring,...Focusing/variable magnification lens group,...Magnification variable lens group.

Claims (1)

[Claims for Utility Model Registration] (1) A fixed tube having a slot extending in the optical axis direction, a cam tube having a cam groove and fitting onto the outer periphery of the fixed tube, and a groove in the fixed tube. a plurality of lens group driving frames that have cam engaging portions that penetrate and engage with cam grooves of the cam barrel and fit into the fixed barrel, and rotate the cam barrel around the optical axis. Preferably, in a zoom lens barrel in which the plurality of lens group drive frames move forward and backward in the optical axis direction, the groove width is such that the cam engaging portion of the lens group drive frame passes through the slot of the fixed barrel. In addition to forming a large relief groove, a bottomed groove or a protrusion extending parallel to the slot in the fixed cylinder, and a bottomed groove in the fixed cylinder separate from the cam engagement part in the lens group drive frame. Alternatively, a zoom lens barrel characterized in that it is provided with an engaging protrusion or groove that engages with the protrusion. (2) The zoom lens barrel according to claim 1, wherein the fixed barrel is made of an integrally molded resin material. (3) The zoom lens barrel according to claim 2, wherein the plurality of lens group driving frames are integrally molded from a resin material.