JP2000292671A - Lens driving device for optical system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To adjust a projected height of a cam pin to be conformed to a deep portion of a cam groove and to properly deform a cam roller when the cam pin moves through a shallow part, so as to eliminate a space between the cam groove and the cam pin, by engaging freely rotatably the cam roller formed of an elastic material with the cam pin, in a lens driving device for moving a lens along an optical axis direction using the cam pin guided by the cam groove formed in an inner circumferential face of a lens-barrel. SOLUTION: A cam pin 25a(26a) is inplanted in an input arm part 21b(22b) provided to direct its rear side toward a rear part of a lens frame 21a(22a), and a cam roller 25b(26b) is fitted freely turnably into the cam pin 25a(26a). An input pin 25(26) comprising the cam pin 25a(26a) and the cam roller 25b(26b) is inserted into a cam groove 27a(27b) penetrated through a straight cam hole 24a formed in a fixed lens-barrel 24, and formed in a turning lens-barrel 27 provided to cover an outside of the fixed lens-barrel 24. A projected height of the cam pin 25a(26a) is adjusted to be conformed to a deep portion of the cam groove 27a(27b).

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a cam lens,
The present invention relates to a lens driving device for guiding the movement of a lens connected to the cam pin in the optical axis direction, and particularly relates to a structure of the cam pin.

[0002]

2. Description of the Related Art For example, a zoom lens device is a device in which a focal length is continuously changed by moving a lens forward and backward in an optical axis direction, and a cam mechanism is used as a moving mechanism of the lens. . A typical mechanism structure is a double structure of a fixed barrel that does not rotate and a rotating barrel that rotates with respect to the fixed barrel, and a cam hole is formed in the barrel located inside. A cam groove with a bottom is formed in a lens barrel located on the outside, a cam pin is implanted in a lens frame holding a lens, the cam pin is inserted through a cam hole, and a tip portion is inserted into the cam groove. is there. That is, when the rotating barrel is rotated with respect to the fixed barrel, the cam pins are guided from both the cam holes and the cam grooves to adjust the amount of movement when moving forward and backward. By making the cam curve of the groove an appropriate shape, the lens can be continuously moved by a predetermined moving amount. If a plurality of lenses are moved while maintaining the optical function by this cam structure, a zooming operation can be performed.

As a zoom lens apparatus having a cam structure of this kind, there is a cam follower for a zoom lens described in, for example, JP-A-59-7319.
This cam follower for a zoom lens prevents rattling between the cam follower and the cam groove. The cam follower for a zoom lens is formed of a hollow cylinder having elasticity and a small friction coefficient. In the case of such a structure, the cam is formed by a through hole, and the cam follower is inserted into the cam hole. Will be prevented.

[0004] When a cam pin as a cam follower is inserted into a cam groove, the depth of the cam groove is not constant, and the cam groove has a depth. It should be noted that if the processing accuracy is increased, the occurrence of shallowness can be suppressed as much as possible, but the processing cost will increase, and the cost of the zoom lens apparatus may increase. In order to smoothly move the cam pin even when the cam groove is shallow, the protrusion length of the cam pin is adjusted according to the shallow portion. 6 and 7 are schematic diagrams illustrating a conventional cam structure of a zoom lens device.
In these figures, a fixed lens barrel 52 in which a cam hole 51 is formed is shown.
A rotatable lens barrel 53 is covered and supported so as to be rotatable, and a cam groove 54 is formed on the inner peripheral surface of the rotatable lens barrel 53. A cam pin 56 is implanted in a lens frame 55 holding a lens (not shown), and a cam roller 57 is rotatably supported on the cam pin 56 so that the cam pin 56 can move smoothly in the cam groove 54. I have. Since the projection length of the cam pin 56 is adjusted to the shallow portion of the cam groove 54, as shown in FIGS. 6 and 7, the cam pin 56 and the cam groove 54 A gap G is formed between the gaps, which may cause play.

[0005] In order to prevent this play, for example, as described in JP-A-6-2500063, a restoring force of a pressing spring by a compression coil spring is applied to the cam pin 56 so that the cam pin 56 is cam grooved. There is a structure to press on the bottom of 54.

[0006]

However, in the above-described structure in which the cam pin 56 and the cam roller 57 are combined, the cam roller 57 is always pressed against the bottom surface of the cam groove 54 by using a pressing spring. , A pressing spring is required, the structure becomes complicated and the number of parts increases,
The assembly work is complicated.

Therefore, according to the present invention, even when the cam groove has a shallow depth, the smooth operation can be performed with a simple structure without play between the cam groove and the cam pin. It is another object of the present invention to provide a lens driving device for an optical device having a cam structure without increasing the number of parts.

[0008]

According to another aspect of the present invention, there is provided a lens driving device for an optical device according to the present invention, wherein a cam hole is provided in a lens barrel at least inside a double lens barrel. A lens frame provided with a cam pin having a cam groove formed in the outer lens barrel, penetrating the cam hole, and having a tip portion inserted into the cam groove, with one lens barrel relative to the other lens barrel. In a lens driving device for an optical device that is rotated to advance and retreat in an optical axis direction, a roller is rotatably supported by the cam pin, and the roller is provided with elasticity.

[0009] The projection length of the cam pin is adjusted to the deep portion of the cam groove. When the cam pin moves in the cam groove, the roller moves while rotating, and when moving in a shallow portion, the cam roller is appropriately deformed and moved by its elasticity. The cam roller may be formed of an elastic material, for example, rubber or plastic having elasticity, or a portion in contact with the cam pin may be formed of metal or synthetic resin, and the outer periphery thereof may be formed of an elastic material such as rubber or plastic having elasticity. May be configured by lining.

According to a second aspect of the present invention, there is provided a lens driving device for an optical device, wherein a portion of the roller contacting a cam pin and a portion of the roller contacting a cam groove are coated with a low friction material. I have.

It is preferable that the portion of the cam roller that contacts the cam pin or the surface that contacts the cam groove is coated with a low friction material because the rotation and movement of the cam roller can be performed smoothly.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a lens driving device for an optical device according to the present invention will be specifically described based on the illustrated preferred embodiments. In this embodiment, a zoom lens device is shown as an example of the optical device.

FIG. 3 to FIG. 5 are views showing the structure of a camera provided with this zoom lens device. This camera includes a first group lens 21, a second group lens 22, and a third group lens 23. The first group lens 21 and the second group lens 22 have a predetermined optical relationship in the optical axis direction. The zoom operation, that is, the zooming operation, is performed by holding and moving. The third group lens 23 moves forward and backward along with the second group lens 22 during the zooming operation, and moves forward and backward with respect to the second group lens 22 during the focusing operation.

Each of the group lenses 21, 22, and 23 is housed in a substantially cylindrical fixed barrel 24. The first lens group 21 is held by a first lens frame 24. This first lens frame 21
The input arm 21b is extended on the outer periphery of
An input pin 25 pointing outward is protruded from an appropriate position of the input arm 21b. As shown in FIGS. 1 and 2, the input pin 25 includes a cam pin 25a protruding from the input arm portion 21b and a cam roller 25b rotatably fitted to the cam pin 25a.
The cam roller 25b is made of rubber, plastic having elasticity, or another elastic material having elasticity. The second group lens 22 is arranged behind the second group lens 21, and is held by a second lens frame 22a. An input arm 22b extending rearward is provided on the outer periphery of the second lens frame 22a, and an input pin 26 pointing outward is projected at an appropriate position of the input arm 22b. Has been established. As shown in FIGS. 1 and 2, the input pin 26 includes a cam pin 26a projecting from the input arm 22b and a cam pin 26a.
26a and a cam roller 26b rotatably fitted to the cam roller 26b. The cam roller 26b is made of rubber, plastic having elasticity, or another elastic material having elasticity.

The input pins 25 and 26 are connected to a fixed lens barrel 24.
A straight cam hole 24a formed by a long hole whose longitudinal direction is the optical axis direction is inserted through the fixed lens barrel 24 to project further outward from the outer peripheral surface of the fixed lens barrel 24.

The fixed lens barrel 24 is attached to the base plate 20 of the camera body, and has a flange portion 24 which is directed outward at the tip.
b is formed. A rotating barrel 27 is provided rotatably with respect to the fixed barrel 24 between the flange portion 24b and the base plate 20. A first cam groove 27a and a second cam groove 27b having cam curves of an appropriate shape are provided on the inner surface of the rotating lens barrel 27.
The tip of the input pin 25 connected to the first group lens 21 is inserted into the first cam groove 27a, and the tip of the input pin 26 connected to the second group lens 22 is connected to the second cam groove. Inserted into 27b. A drive gear unit 28 is provided at the outer rear end of the rotating lens barrel 27. As shown in FIG. 3, the output rotation of the variable-power drive motor 29 is rotated via an appropriate gear train 30. It is transmitted to 28.

As shown in FIGS. 3 to 5, a motor bracket 8 is mounted on the second lens frame 22a, and a focusing drive motor 9 is mounted on the motor bracket 8. The second lens frame 22a has a guide rod 5 whose longitudinal direction is parallel to the optical axis.
a and 5b are supported. The drive shaft 10 of the focusing drive motor 9 is inserted through the frame holder 6 provided on the third lens frame 23a, and the frame 11 connected to the frame holder 6 is incorporated so as not to drop off from the frame holder 6. Linked piece
A female screw portion formed on the inner surface of 11 is screwed with a male screw portion of the drive shaft 10. The guide rod 5b is a third
The guide rod 5a is inserted through a guide portion 7 provided on the lens frame 23a, and the guide rod 5a is inserted through a fork portion (not shown) formed in a fork shape on the third lens frame 23a.

The operation of the embodiment of the zoom lens device provided with the lens driving device according to the present invention constituted as described above will be described below.

First, the operation of a camera provided with this zoom lens device will be described with reference to FIGS. FIG.
Indicates a collapsed state in which the camera is not used for photographing, and includes a first group lens 21, a second group lens 22, and a third group lens.
Both of them are retreating to the end.

In this collapsed state, when the variable power drive motor 29 is operated and its output rotation is transmitted to the drive gear 28,
The rotating barrel 27 rotates with respect to the fixed barrel 24. Rotating lens barrel 24
The input pins 25, 26 penetrating the straight cam holes 24a of the fixed lens barrel 24 are inserted into the cam grooves 27a, 27b formed in the first cam groove 27a. Is moved by the second cam groove 27b, and moves in the optical axis direction. For this reason, the first group lens 21 to which the input pin 25 is linked and the second group lens 22 to which the input pin 26 is linked are moved by different amounts while maintaining a predetermined optical relationship, as shown in FIG. The zooming operation is performed between the telephoto position and the wide-angle position shown in FIG.

The cam pins 25a, 26a of the input pins 25, 26
Of the first cam groove 27a and the second cam groove 27a, respectively.
Adjust to the deepest part of b. For this reason,
When these input pins 25, 26 move in the cam grooves 27a, 27b, the cam rollers 25b, 26b in contact with the cam surfaces of the cam grooves 27a, 27b rotate, so that they move smoothly. Then, in the shallow portions of the cam grooves 27a and 27b, the cam rollers 25b and 26b move in a state where they are appropriately deformed by their elasticity. Therefore, the input pins 25 and 26 can always move smoothly in the cam grooves 27a and 27b.

The third group lens 23 moves with the second group lens 22 because the bracket 8 and the guide rods 5a and 5b are attached to the second lens frame 22a of the second group lens 22. When a focusing operation is performed, the drive motor 9 is operated to rotate the drive shaft 10 based on distance information to the subject obtained by a distance measuring device (not shown). The drive shaft 10 is formed with a male screw portion 10a, and the female screw portion 11a of the connecting piece 11 is screwed to the male screw portion 10a.
Move along 10 in a direction parallel to the optical axis. This connection piece
Since the frame 11 is accommodated in the frame holder 6 formed in the third lens frame 23a, the third lens frame 23a is moved by the movement of the linked frame 11, and the third group lens 23 is moved in the optical axis direction. Then, the movement of the third group lens 23 brings the imaging optical system into focus. In addition, the moving direction of the linkage piece 11 is changed according to the rotation direction of the drive shaft 10, and the third lens group 23 can be moved forward and backward. In addition, each lens group 21,
When 22, 23 are in the collapsed state, as shown in FIG.
The third lens group 23 is moved to a position close to the second lens group 22 to shorten the overall length in the optical axis direction, thereby reducing the thickness of the camera.

[0023]

As described above, according to the lens driving device of the present invention, since the cam roller rotatably supported by the cam pin is formed of an elastic material, the length of the cam pin protruding is reduced by the depth of the cam groove. When moving along a shallow portion of the cam groove, the cam roller moves while rotating in a state where the cam roller is appropriately deformed. Therefore, there is no gap between the cam roller and the cam groove, and the cam pin does not rattle, so that the lens connected to the cam pin can be surely moved by a predetermined moving amount, and a smooth operation can be achieved. Can be performed. In addition, since a pressing spring or the like for urging the cam roller is not required, the number of components is not increased, and the cost is not increased.

[Brief description of the drawings]

FIG. 1 is a schematic diagram illustrating the structure of a lens driving device according to the present invention, and is a cross-sectional view taken along a plane orthogonal to an optical axis.

FIG. 2 is a schematic diagram illustrating the structure of a lens driving device according to the present invention, and is a cross-sectional view cut along a plane including an optical axis.

FIG. 3 is a schematic longitudinal sectional view of a camera equipped with a zoom lens device using a lens driving device according to the present invention, showing a state in which a photographing optical system is in a retracted position.

FIG. 4 is a schematic longitudinal sectional view of a camera equipped with a zoom lens device using a lens driving device according to the present invention, and shows a state where an imaging optical system is at a telephoto position.

FIG. 5 is a schematic longitudinal sectional view of a camera equipped with a zoom lens device using a lens driving device according to the present invention, and shows a state where an imaging optical system is at a wide angle position.

FIG. 6 is a schematic exploded perspective view illustrating the structure of a conventional lens driving device, and is a diagram corresponding to FIG.

7 is a schematic exploded perspective view illustrating the structure of a conventional lens driving device, and is a diagram corresponding to FIG.

[Explanation of symbols]

 21 First group lens 21a First lens frame 21b Input arm 22 Second group lens 22a Second lens frame 22b Input arm 23 Third group lens 23a Third lens frame 24 Fixed lens barrel 24a Straight cam hole 25 Input pin 25a Cam pin 25b Cam roller 26 Input pin 26a Cam pin 26b Cam roller 27 Rotating lens barrel 27a First cam groove 27b Second cam groove

 ──────────────────────────────────────────────────続 き Continuation of the front page (72) Inventor Mitsumi Misawa 3-11-46 Izumi, Asaka-shi, Saitama Prefecture Inside Fujisha Shin Film Co., Ltd. (72) Inventor Shigeru Kondo 3-11-46 Izumi, Asaka-shi, Saitama Fujisha Shin Film Co., Ltd. F-term (reference) 2H044 BD08 BD09 BD16 BD18 BD20 BE02 BF03 DA02 DB02 DD03 DD08

Claims (2)

[Claims] 1. A cam hole is formed in an inner barrel of at least a double combination of barrels, and a cam groove is formed in an outer barrel. The cam hole is penetrated, and a tip is inserted into the cam groove. A lens frame provided with a cam pin, wherein one lens barrel is rotated with respect to the other lens barrel to advance and retreat in an optical axis direction. A lens driving device for an optical device, wherein the lens driving device is supported, and the roller is provided with elasticity. 2. A lens driving device for an optical device according to claim 1, wherein a low friction material is coated on a portion of the roller that contacts the cam pin and a portion of the roller that contacts the cam groove.