JPS60112008A - Zoom driving device for zoom lens - Google Patents

Abstract

PURPOSE:To move a front and a rear movable lens in two groups with a small force by moving the movable lenses in an optical axis direction through a front and a rear different cam ring supported on a zooming shaft parallel to an optical axis, and rotating the cam ring through a rotating mechanism associatively with the rotation of the zooming shaft. CONSTITUTION:The front and rear cam rings 31 and 32 corresponding to the front and rear movable lenses 12 and 13 are provided on the zooming shaft 30 individually, and cam grooves 33 and 34 which engage frame bodies 15 and 16 of the movable lenses in two groups to move the frame bodies 15 and 16 associatively with the rotation are formed in both cam rings 31 and 32. Further, the rotating mechanism consisting of a pinion 36, internal gears 37 and 38, the 2nd interlocking pinion 40, etc., is provided to rotate the front and rear cam rings 31 and 32 associatively with the rotation of the zooming shaft 30.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a zoom drive mechanism for a zoom lens, and in particular, by rotating a zooming axis provided parallel to the optical axis, at least two groups of movable lenses, front and rear, are moved to change the focal length. This invention relates to improvement of a type of zoom lens that changes the

This type of zoom lens is, for example,
No. 729 proposes this, and its basic configuration is shown in Figures 1 and 2. The illustrated example is a four-group lens system, which in order from the front includes a focusing lens 11, a parry lens 12, a compensator lens 13, and a fixed master lens (not shown). A variator lens 12 and a compensator lens 13 are movable lenses involved in zooming, and are fixed to a variator lens frame 15 and a compensator lens frame 16, respectively. The variator lens frame 15 and the compensator lens frame 16 are supported by a sliding rotating portion of Miki's guide ball (only Ichiki is shown in the figure) 18 which is fixed to the lens barrel 17 parallel to the optical axis.

On the outside of these lens systems, a zooming shaft (cam shaft) 20 parallel to the optical axis, shown at the bottom of FIG. 1, is rotatably supported. This zooming shaft 20 is directly connected to the variator lens frame 15 and the compensator lens frame 16 on its circumferential surface.
Miki's cam l+M2t, 22 corresponding to the cam groove 21.22 is formed with a variator lens %15,
An interlocking protrusion 23 protruding from the compensator lens frame 16.
24 is fitted.

The cam grooves 21 and 22 are formed in the variator lens frame 15 and the convencator L/7 frame 16 as the zooming shaft 2o rotates.
That is, the variator lens 12 and the compensator lens 13 are moved in the optical axis direction in a predetermined relationship to change the combined focal length of the entire lens system. Therefore, by rotating the zooming shaft 20, zooming can be performed. Note that focusing is 1
However, the present invention does not care about any focusing mechanism.

However, in this conventional device, since the cam grooves 21 and 22 are formed directly on the single zooming lever 2o, there is a problem in that a large force is required to drive the movable lens, especially the variator lens 12. In other words, with a zoom lens, the number of movements of the variator lens 12 needs to be large, whereas with the compensator lens 13, the number of movements is large.
-1 The amount of movement may be small. However, in the conventional device which forms the cam grooves 21 and 22 directly on the zooming foot 2o, both grooves 2o
1.22 cannot be provided around the outer periphery of the zooming shaft 20 for more than one circumference because they interfere with each other. Therefore, the inclination of the cam groove 21 on the lens side, which has a particularly large amount of movement, becomes steep (the inclination angle shown in Fig. 2). α becomes larger), and as a result, the frictional force between the cam groove 21 and the interlocking protrusion 23 becomes thicker, which tends to make sliding difficult, and there is a problem that zooming cannot be performed unless the rotational force of the zooming shaft 20 is increased. there were.

The present invention has been made based on such an awareness of the problem, and includes a zoom lens of the above type in which zooming is performed by rotation of a zooming shaft provided parallel to the optical axis of the lens, in which a cam groove is formed directly on the zooming shaft. without any
Front and rear cam rings corresponding to the front and rear movable lenses are separately provided on the 8-ring axis, and both cam rings are engaged with the frames of the two groups of movable lenses to rotate. A cam groove is formed to move the frame in the optical axis direction, and a rotation mechanism is provided to rotate the front and rear cam rings in conjunction with the rotation of the zooming shaft. It is a feature.

The invention will now be described with reference to the illustrated embodiments. FIG. 3 shows an embodiment of the present invention, in which the same components as those of the conventional device 11'A are designated by the same reference numerals. The zooming axis 30 parallel to the optical axis is made of a round bar without a special cam groove, and cam rings 31 and 32 separately configured for the variator lens 12 and the compensator lens 13 are attached to the outer periphery of the zooming @b30, respectively. It is fitted so that it can rotate freely while restricting movement in the axial direction. And this cam ring 31.3
2 are formed with cam grooves 33 and 34 into which the ae protrusion 23 of the variator lens frame 15 and the interlocking protrusion 24 of the compensator lens frame 16 are fitted, respectively. 35
shows a regulating flange that projects from the zooming shaft 30 to regulate the axial movement of the cam rings 31, 32.

A pinion 36 is fixed or directly formed and integrated with the zooming shaft 30. An internal gear 37 is formed at the front end of the cam ring 32 so as to match the pinion 36 in the axial direction, and the other cam ring 31
An internal gear 38 is formed at its rear end.

The pinion 36 and the internal gears 37 and 38 are coaxially interlocked by an integral interlocking pinion 39 and a second interlocking pinion 40, and when the zooming shaft 30 rotates,
The cam rings 31, 32 are configured to rotate. That is, coaxial and integral interlocking pinions 39 and 40 are rotatably supported by a part of the lens barrel 17 at their center, and the interlocking pinion 39 meshes with the pinion 36 and the internal gear 37 at the same time, and the interlocking pinion 40 meshes with the internal gear 38.

Therefore, when the zooming shaft 30 is rotated, the pinion 36 integrated with the zooming shaft 30 rotates, and the internal gear 37, that is, the cam ring 32 is rotated through the interlocking pinion 39 that meshes with the pinion 36. rotates. Further, since the second interlocking pinion 40 integrated with the interlocking pinion 39 also rotates, the internal gear 38, that is, the cam ring 31, rotates. The cam rings 31 and 32 rotate in the same direction. Therefore, according to the cam grooves 33 and 34, the variator lens frame 1
5. The compensator lens frame 16 will move in the optical axis direction.

The number of rotations of the cam ring 32 and the cam ring 31 per one rotation of the zooming shaft 30 can be freely set by appropriately selecting the number of teeth of the interlocking pinion 39, 40 and the gear that interlocks with it. I can do something. Therefore, the degree of freedom in setting the inclination of the cam grooves 33 and 34 formed in the cam rings 31 and 32, especially the inclination of the cam groove 33 on the movable lens side that has a large amount of movement, is increased, and the inclination can be set gently as shown in Fig. 3. Therefore, the variator lens frame 15 can be moved with a light force. Also, the cam groove 33 is connected to the cam ring 31.
Since the cam ring 31 can be provided around the outer circumference of the cam ring 31,
The diameter of this type of zoom lens can be reduced by reducing the diameter C of the lens.

In the above embodiment, both the cam rings 31 and 32 are rotatably supported with respect to the zooming shaft 30, but on the other hand, for example, the cam ring 32 is rotated around the zooming shaft 30, and only the cam ring 31 is supported with respect to the zooming shaft 30. The cam ring 31 may be rotatably supported so that the cam ring 31 is rotated in conjunction with the rotation of the zooming shaft 30.

The zooming shaft 30 can be rotated either manually or electrically. In the case of a cell that is manually rotated, a zooming operation ring may be rotatably supported outside the lens barrel 17, and this operation ring and the zooming shaft 30 may be interlocked via a gear mechanism or the like. Further, when performing electric zooming, the zooming shaft 30 may be directly rotated by an electric motor.

In the embodiment described above, the present invention is applied to two groups of movable lenses, the variator lens and the compensator lens, in a zoom lens having a focusing lens, a variator lens, a compensator lens, and a master lens. The present invention can be applied to all types of zoom lenses in which the focal length is changed by moving the front and rear movable lens groups.

As described above, the present invention has two movable lens groups, front and rear, which are moved in the optical axis direction by rotation of separate front and rear cam rings supported on a zooming axis parallel to the optical axis. Since the cam ring rotates in conjunction with the rotation of the zooming shaft through a rotation mechanism, the rotation angle of the zooming axis and the rotation angle of the cam ring can be adjusted by setting the rotation mechanism. A degree of freedom is obtained in the relationship, and therefore, there is an effect that a movable lens, which has a particularly large amount of movement, can be moved with a small force.

[Brief explanation of drawings]

Fig. 1 is a vertical cross-sectional view of the main parts showing an example of a zoom drive device for a conventional zoom lens, Fig. MS2 is a developed view of a cam groove formed in the zooming shaft of Fig. 1, and Fig. 3 is a diagram of the zoom drive device of the present invention. FIG. 2 is a vertical cross-sectional view of essential parts of an embodiment of a zoom drive device for a zoom lens. 12... Variator lens (movable lens), 13...
- Compensator lens (movable lens), 15... Variator lens frame, 16... Compensator lens frame, 23.24... Interlocking projection, 30... Zooming axis, 31. 32... Cam ring, 33 .34...cam groove,
36...Pinion, 37.38...Internal gear, 39
... Interlocking pinion, 4o... Second interlocking pinion. Patent applicant: Asahi Optical Industry Co., Ltd. Agent: Kunio Miura Figure 2

Claims (1)

[Claims] (1) A zooming shaft is rotatably supported parallel to the optical axis of a zoom lens having at least two front and rear movable lens groups, and by rotating this zooming shaft, the two front and rear movable lens groups are moved. In the zoom drive device for the zoom lens, on the zooming axis,
Front and rear cam rings corresponding to the front and rear movable lenses are separately provided, and these cam rings are engaged with the frames of the two groups of movable lenses to move the frames as they rotate. A zoom lens comprising a cam groove for moving in the optical axis direction, and a rotation mechanism for rotating the front and rear cam rings in conjunction with the rotation of the zooming shaft. Zoom drive device. (2. In claim 1, both the front and rear cam rings are rotatably supported on the zooming shaft, and one cam ring and the zooming shaft are integrally provided on the zooming shaft. A pinion, an interlocking pinion that meshes with this pinion, and an internal gear formed on one of the cam rings that meshes with this interlocking pinion. 1. A zoom drive device for a zoom lens that is interlocked with the zooming shaft through an interlocking pinion and an internal gear provided on the other cam ring that meshes with the second interlocking pinion.