JPH0682614U - Lens frame drive mechanism - Google Patents

Abstract

(57) [Summary] [Object] To provide a lens frame drive mechanism that can easily realize downsizing of a lens frame and can easily perform static adjustment of a relative position between lens frames during assembly. A long-span cam 12 having a relatively long transfer span, which is provided so as to be located on the peripheral surface of the tubular body for driving the lens frame, and the tubular body for driving the other lens frame. A short span cam 13 having a relatively short transfer span and provided coaxially with the tubular body with the end face side as a cam surface, a cam follower member 5c corresponding to the long span cam 12 and a lens frame 5 corresponding to the cam follower member. A relative position and / or an adjusting mechanism for permitting static adjustment of a relative position between the cam follower member 6c corresponding to the short span cam 13 and the lens frame 6 corresponding to the cam follower member. And a lens frame drive mechanism.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention relates to a lens frame driving mechanism, and more particularly to a lens frame driving mechanism suitable for a variable lens barrel of a camera.

[0002]

[Prior art]

 Conventionally, as a lens frame driving mechanism in a zoom lens frame, a zoom lens barrel for moving two sets of zoom lens groups as shown in FIG. 5 has been put to practical use. These two sets of zoom lenses are moved along independent extension curves corresponding to zooming, thereby satisfying the high magnification and wide angle of view of the zoom lens barrel.

That is, this zoom lens barrel is a zoom lens barrel having a five-group structure, and includes a first group lens holding frame 142 for holding the first and fourth group lenses in the lens frames 140 and 150, and The fourth group lens holding frame 145 is fixedly supported. Further, the second group lens holding frame 143 and the third group lens holding frame 144, which individually hold the second and third group lenses constituting the zoom lens, respectively, are provided by the guide shaft 141 supported by the lens frame 140. It is supported so that it can move back and forth in the axial direction. The fifth group lens holding frame 146, which holds the fifth group lens which is the focus lens, is supported by a guide shaft 154 supported by the rear lens frame 150 so as to be movable back and forth in the optical axis direction. An optical filter 147 and a CCD 148 are provided behind the fifth lens group. A diaphragm 155 driven by a diaphragm motor 156 is arranged on the fourth group lens holding frame 145. The fifth lens group holding frame 146 is driven back and forth by a focusing motor 157 during focusing operation.

The second group lens holding frame 143 and the third group lens holding frame 144 are moved along different predetermined feeding curves during the zooming operation. The drive is performed by rotating the cam ring 151 by a zoom motor (not shown) and via a cam groove provided in the cam ring 151.

[0005]

[Problems to be solved by the device]

 However, although it can be said that the lens barrel shown in FIG. 5 described above is satisfactory for the zoom function, a ring-shaped cam ring is used to drive a plurality of lens holding frames, and There was a problem that the outer shape became large. Further, when applied to a lens barrel in which the lens holding frame is arranged across the diaphragm mechanism, the diameter of the cam ring must be increased in order to avoid interference with the diaphragm mechanism, Further, there is a problem that the outer shape of the lens barrel becomes large. This has been an obstacle to providing a compact camera that is easier to handle and has higher performance, especially in a situation where image pickup devices such as CCDs are miniaturized in video cameras and the like.

Further, even if an attempt is made to apply a feed screw mechanism which is arranged on one axis for driving the plurality of lens holding frames instead of the above-mentioned cam ring, in view of zooming operation, each lens holding frame is moved. Was impossible because it had to be driven along different payout curves.

The present invention has been made in order to solve these drawbacks, and the miniaturization of the lens frame can be easily realized, and the static adjustment of the relative position between the lens frames at the time of assembly can be easily performed. It is an object of the present invention to provide a lens frame drive mechanism that can be performed.

[0008]

[Means for Solving the Problems]

 The lens frame drive mechanism of the present invention is designed to drive the lens frame by driving a long span cam having a relatively long transfer span, which is provided so as to be located on the peripheral surface of the cylindrical body, and another lens frame. A short span cam having a relatively short transfer span and provided coaxially with the tubular body with the end surface side of the tubular body as a cam surface, a cam follower member corresponding to the long span cam, and a mirror corresponding to the cam follower member. A relative position with respect to the frame, and / or a cam follower member corresponding to the short span cam, and an adjustment mechanism for permitting static adjustment of the relative position with respect to the lens frame corresponding to the cam follower member. Characterize

[0009]

[Action]

 By rotating the long-span cam and the short-span cam coaxially within a predetermined range, the respective lens frames are displaced, and the relative position deviation between the lens frames and the span cams that occurs during the assembly of this mechanism. Are adjusted by corresponding movable cam follower members.

[0010]

【Example】

 Hereinafter, the present invention will be described with reference to an illustrated embodiment. 1 to 4 show a lens frame driving mechanism showing an embodiment of the present invention. As shown in FIG. 1, in this lens frame driving mechanism, each of the supporting pieces 5d, 6d of the second group lens holding frame 5 and the third group lens holding frame 6 has a fitting hole 5a into the supporting guide shaft 7. Driven pins 5c and 6c, which are cam follower members, which are respectively in contact with the cam surfaces of the rib cam 12 which is a long span cam and the end surface cam 13 which is a short span cam are mounted in the vicinity of 6a and 6a. The rib cam 12 is a long span cam having a long transfer distance and is formed of a cam having a convex rib-shaped cam surface 12a having a predetermined lead angle, and the end face cam 13 is an end face cam having a short transfer distance and a short span cam. Is formed by. The driven pin 5c is brought into contact with the rib-shaped cam surface 12a of the rib cam 12 by the urging force of the plate spring portion 5b formed integrally with the holding frame 5. The driven pin 6c is brought into contact with the cam surface of the end cam 13 by the urging force of the tension spring 14 suspended between the holding frames 6 and 5.

The rib-shaped cam surface 12 a provided on the rib cam 12 has a predetermined lead in the range of a rotation angle of 320 °. Further, the working cam surface provided on the end surface cam 13 also has a cam surface in the range of a rotation angle of 320 °. FIG. 2 shows the relationship between the rotation angles of the cams, that is, the movement amounts of the holding frames 5 and 6 between the zoom positions W (wide) and T (tele), that is, the lens extension amounts. As shown in FIG. 2, between the zoom positions W to T, the second group lens 3 extended by the rib cam 12 is extended linearly for a long distance, and the third group lens 3 extended by the end face cam 13 is compared. Is played for a short distance. These characteristics are determined by the optical design requirements of the lens.

FIG. 3 is a vertical cross-sectional view of the main mechanical portion of the zoom lens barrel having the lens frame drive mechanism shown in FIG. This zoom lens barrel is a five-group zoom lens, and the first group lens 2 is supported by the outer frame 1 that is a tubular body, and the second group lens 3 and the third group lens that form the zoom lens. Reference numeral 4 denotes a supporting guide shaft 7 and a rotation stopping guide shaft 8 (supported by the outer frame 1 and held by the second group lens holding frame 5 and the third group lens holding frame 6 which are lens frames, respectively. (See FIG. 1), it is supported so that it can move back and forth in the optical axis O direction. Behind the third lens group 4, although not shown, a fourth lens group, which is a fixed lens group, and a fifth focus lens driven to focus in the optical axis O direction, like the lens barrel shown in FIG. A group lens, an optical filter and a CCD are arranged along the optical axis O.

The driving of the second group lens holding frame 5 and the third group lens holding frame 6 in the optical axis O direction is performed by the rotation of the rib cam 12 and the end surface cam 13 coaxially fixed to the cam shaft 10. It is done by movement. The cam shaft 10 is rotatably supported by the outer frame 1 in the vicinity of the supporting guide shaft 7 and constitutes an interlocking mechanism that drives the cam 12 and the cam 13 in an interlocking manner. A gear 11, which is rotated by a zoom motor 15 via a gear train 16, is fixed to the gear 10.

The zoom lens barrel configured as described above includes two zoom lenses, a second zoom lens group and a second zoom lens group, which include a rib cam 12 and an end surface cam 13 each having a relatively small diameter provided near the guide shaft 7. Since the lens is moved along the desired locus, it is possible to increase the magnification of the zoom lens, widen the angle of view, and facilitate control. At the same time, the small-diameter rib cam 12 and end surface are mounted on a single cam shaft 10. Since the cam 13 is provided, a large-diameter cam ring unlike the conventional lens barrel is unnecessary, and the enlargement of the lens barrel outer shape can be avoided. Further, even for an optical system in which a diaphragm is arranged between the second lens group 3 and the third lens group 4, the drive mechanism of this zoom lens barrel includes the cam member in the vicinity of the guide shaft 8. It is provided only and is easy to apply.

Further, the rib cam 12 and the end surface cam 13 can be formed as a molding part formed by integral molding. In this case, the end surface cam 13 side performs die cutting in the axial direction, and the rib cam 12 side performs die cutting in the torsional direction along the lead. Although the outer frame 1 is used in the above example, this is not always necessary, and it is of course possible to reduce the size by configuring the camera body to hold each component.

By the way, normally, in the lens frame drive mechanism, since a plurality of lenses are continuously moved within a predetermined range to be displaced, each lens frame cannot be displaced by itself. Therefore, the second group lens holding frame based on the manufacturing error and the component size error of the rib cam 12 which is a long span cam having a long transfer distance and the end cam 13 which is a short span cam having a short transfer distance, which occur at the time of assembling the lens frame. There is a problem in that the error between the lens group 5 and the third lens group holding frame 6 cannot be adjusted.

Therefore, in the present invention, the lens frame drive mechanism is provided with an adjusting mechanism for eliminating this problem. That is, in this adjusting mechanism, the driven pins 5c and 6c, which are cam follower members, are constituted by screw shafts, respectively, and are screwed so as to penetrate the support pieces 5d and 6d. FIG. 4 is a perspective view of a main part for explaining the details of the adjusting mechanism. This FIG. 4 has substantially the same structure as the lens barrel shown in FIG. The embodiment of the adjustment mechanism shown in FIG. 4 is for fine adjustment of the distance between the third group lens holding frame 6 (see FIGS. 1 and 3) and the second group lens holding frame 5 at the reference zoom position during assembly. Is shown. The distance between the second and third lens group holding frames is an important dimension in terms of zooming accuracy, and has a great influence on focus shift and the like due to zooming. Therefore, the zooming accuracy of the lens barrel is improved by making the above intervals adjustable.

In this embodiment of the adjusting mechanism, the driven pin 5c also serving as the adjusting screw is screwed to the support piece 5d provided on the second group lens holding frame 5. On the other hand, a rib cam 12 which is a long span cam having a rib-shaped cam surface 12a and an end face cam 13 which is a short span cam are fixed to the cam shaft 10 in a predetermined phase relationship. A tension spring 14 is suspended on the holding frame 5.

In the embodiment configured as described above, when the lens frame is assembled, the cam shaft 10 is fixed to the zoom rotation position as the adjustment reference, and in that state, the driven pin 5c is rotationally adjusted. By doing so, the interval between the third group lens holding frame (not shown) and the second group lens holding frame 5 is set to a predetermined distance. By adjusting in this way, it is possible to adjust the error between the second and third lens group holding frames based on the error between the rib cam 12 and the end cam 13 and the error in the component dimensions.

Note that this adjusting mechanism can be similarly applied to the third group lens holding frame. That is, in FIG. 1, the same adjustment as described above is performed by screwing the follower pin 6c, which also serves as an adjusting screw, to the supporting piece 6d of the third group lens holding frame 6 in the vicinity of the fitting hole 6a into the supporting guide shaft 7. Is possible.

As described above, in the adjusting mechanism according to the present embodiment, the cam follower member is skillfully used and the movement thereof can be adjusted, so that the deviation between the lens holding frames can be removed at the time of assembly.

[0022]

[Effect of device]

 As described above, according to the lens frame driving mechanism of the present invention, the long span cam and the short span cam are coaxially rotated within a predetermined range to displace a plurality of lens frames in conjunction with each other. Therefore, for example, it is easy to achieve a high magnification and a wide angle of view in the zoom lens barrel, and drive control can be simplified. In addition, the lens frame can be downsized. Further, due to the configuration of the lens frame drive mechanism, an error due to a relative position shift between the lens frames, which may possibly occur, can be eliminated by allowing static adjustment of the cam follower member during assembly.

[Brief description of drawings]

FIG. 1 is a perspective view of a main part of a lens frame drive mechanism showing an embodiment of the present invention.

FIG. 2 is a diagram showing a lens extension amount in the lens frame drive mechanism of FIG.

FIG. 3 is a vertical cross-sectional view of the upper half of the main part of the lens barrel that incorporates the lens frame drive mechanism of FIG.

FIG. 4 is a perspective view of an essential part showing an example of an adjusting mechanism of the present invention in the lens frame driving mechanism.

FIG. 5 is a vertical cross-sectional view of a lens barrel having a five-group configuration including a conventional lens frame driving mechanism.

[Explanation of symbols]

 5c, 6c ··· Driven pin (cam follower member) 10 ··· Cam shaft (interlocking mechanism) 12 ··· Rib cam (long span cam with long transfer span) 13 ··· End cam (short span cam with short transfer span)

Claims (1)

[Scope of utility model registration request] 1. A long-span cam having a relatively long transfer span provided so as to be located on the peripheral surface of a tubular body for driving the lens frame, and the tubular body for driving the other lens frame. A relative position between a short span cam having a relatively short transfer span provided coaxially with the cylindrical body with the end face side as a cam surface, a cam follower member corresponding to the long span cam, and a lens frame corresponding to the cam follower member, and/
Alternatively, a lens frame drive mechanism comprising: a cam follower member corresponding to the short span cam and an adjustment mechanism for permitting static adjustment of a relative position between the lens follower member and the lens frame corresponding to the cam follower member.