JP2003315660A - Lens driving device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To prevent a cam follower from falling off from a cam groove due to excessive movement, in a lens driving device using the cam groove and the cam follower. <P>SOLUTION: The lens driving device is provided with a fixed cylinder 20 possessing the cam groove 21 performing a cam action in an optical axis direction L and a cylindrical cam 30 possessing the cam follower 31 holding a lens and guided by being inserted into the cam groove 21, and when the lens is moved in the optical axis direction by rotating the cylindrical cam 30, the fixed cylinder 20 is provided with a stopper 23, and the cylindrical cam 30 is provided with an abutting piece 32, so that the abutting piece 32 abuts on the stopper 23 before the cam follower 31 reaches the terminating part 21e of the cam groove 21. Thus, the excessive movement of the cam follower 31 is regulated, so that fall-off from the cam groove 21 can be prevented. <P>COPYRIGHT: (C)2004,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a lens driving device for moving a lens in an optical axis direction, and more particularly to a lens driving device including a cam groove and a cam follower as a driving mechanism.

[0002]

2. Description of the Related Art As a conventional lens driving device, a cam follower is provided in a lens holding frame holding a lens, a cam groove for receiving the cam follower is provided in an inner peripheral surface of a lens barrel for housing the lens holding frame, and the lens barrel is rotated. By doing so, it is known that the cam groove exerts a cam action on the cam follower to move the lens holding frame in the optical axis direction. Further, the two lens barrels are coaxially arranged in a nested manner, a cam groove is provided on the inner peripheral surface of the outer lens barrel, and a cam follower to be inserted into the cam groove is provided on the outer peripheral surface of the inner lens barrel. It is known that an inner lens barrel is moved in the optical axis direction by applying a rotational driving force to the lens barrel. In the drive mechanism using the cam groove and the cam follower, the extension movement of the lens holding frame or the lens barrel in the optical axis direction is restricted when the cam follower reaches the end portion of the cam groove. .

On the other hand, in recent lens drive devices,
In order to improve the drop strength or suppress the image shake phenomenon,
There is a tendency to set the mounting play between the lens holding frame or the lens barrel having the cam follower and the lens barrel having the cam groove as small as possible. As a result, the driving load becomes large due to the increase of the frictional force in the area where the relative movement occurs. Therefore, the gear ratio is made higher and the driving force is made larger.

[0004]

By the way, in the above lens driving device, the movement of the lens holding frame or the lens barrel (extending position) is restricted by the cam follower reaching the end portion of the cam groove. Since it was regulated by colliding with the wall surface, if the driving force was set to a large value, the cam follower would ride over the end of the cam groove and move excessively, and the lens would not be positioned accurately.
Further, the return operation may be difficult due to the biting of the cam follower.

The present invention has been made in view of the above-mentioned problems of the prior art, and an object of the present invention is to obtain desired optical characteristics while ensuring desired mechanical strength and suppressing image shake. It is an object of the present invention to provide a lens driving device that can secure a driving operation with a simple structure.

[0006]

A lens driving device of the present invention has a cam member having a cam groove which cams in the optical axis direction, and a cam follower which holds a lens and is inserted and guided in the cam groove. A lens driving device comprising a follower member and moving a lens in the optical axis direction by relatively moving the cam member and the follower member, wherein the cam follower includes a cam follower at an end of a cam groove. Before reaching the section, it is characterized in that a regulation means for regulating the relative movement of both is provided.

According to this structure, when the follower member moves relative to the cam member, the cam follower is guided by the cam groove, and the follower member (lens) is moved in the optical axis direction. Then, before the cam follower reaches the end of the cam groove, the restricting means acts to restrict the relative movement of the two, and positions the lens at the end position of the moving range. Therefore, a collision between the cam follower and the end of the cam groove is avoided, the cam follower is prevented from falling out of the cam groove, and a reliable drive operation is performed.

In the above structure, the restricting means may be so structured as to restrict the relative movement of the cam member and the follower member at the maximum extended position of the lens. According to this configuration, when the follower member moves relative to the cam member, the cam follower is guided by the cam groove, and the follower member (lens) is moved to the maximum feeding position, the cam follower moves in the cam groove. Before reaching the end portion, the restricting means operates to restrict the relative movement of the both, and positions the lens at the maximum extension position. Therefore, the collision between the cam follower and the terminal end of the cam groove on the feeding side is avoided, the cam follower is prevented from falling out of the cam groove, and a reliable driving operation is performed.

In the above structure, the base, the fixed barrel fixed to the base and having an axis in the optical axis direction, and the lens holding frame for holding the lens supported inside the fixed barrel so as to reciprocate in the optical axis direction. And a drive source for driving the lens holding frame, the cam member is the fixed cylinder having a cam groove formed on the inner peripheral surface thereof, and the follower member is the lens holding frame having the cam follower formed, and the regulating means. Comprises a stopper formed to project on the inner peripheral surface of the fixed barrel, and an abutting piece formed on the lens holding frame and capable of abutting the stopper.
Configuration can be adopted.

According to this structure, when the lens holding frame (follower member) is moved relative to the fixed barrel (cam member) by the drive source, the cam follower is guided to the cam groove, and the lens holding frame. The (lens) is moved in the optical axis direction. Then, before the cam follower reaches the end of the cam groove, the restricting means acts to restrict the relative movement of the two, and positions the lens at the end position of the movement range (for example, the maximum extension position). Therefore, a collision between the cam follower and the end of the cam groove is avoided, the cam follower is prevented from falling out of the cam groove, and a reliable drive operation is performed.

Further, in the above structure, the base, the fixed barrel fixed to the base and having an axis in the optical axis direction, and supported by the fixed barrel inside the fixed barrel so as to be retractable in the optical axis direction and have a cam action. A cylindrical cam, a plurality of lens holding frames that hold the lens and that are arranged inside the cylindrical cam and are moved in the optical axis direction by the cam action of the cylindrical cam, and a drive source that exerts a rotational driving force on the cylindrical cam. And the cam member is
The follower member is the fixed cylinder having a cam groove formed on the inner peripheral surface, the follower member is the cylindrical cam having a cam follower formed on the outer peripheral surface, and the restricting means is a stopper formed to project on the inner peripheral surface of the fixed cylinder. , An abutting piece that is formed so as to project on the outer peripheral surface of the cylindrical cam and that can abut the stopper,
Configuration can be adopted.

According to this structure, when the cylindrical cam (follower member) is moved relative to the fixed cylinder (cam member) by the drive source, the cam follower is guided to the cam groove, and the cylindrical cam and the plurality of cams are guided. The lens holding frame (plurality of lenses) is moved in the optical axis direction. Then, before the cam follower reaches the end of the cam groove, the restricting means acts to restrict the relative movement of the cylindrical cam and the fixed cylinder, and the lens is moved to the end position (for example, the maximum feeding position) of the moving range. To position. Therefore, a collision between the cam follower and the end of the cam groove is avoided, the cam follower is prevented from falling out of the cam groove, and a reliable drive operation is performed. Further, since the excessive movement of the cylindrical cam is restricted, the plurality of lens holding frames driven by the cam action of the cylindrical cam can be surely driven without excessive movement.

[0013]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the accompanying drawings. 1 to 7
Shows an embodiment of a lens driving device according to the present invention,
1 is a front view of the device, FIGS. 2 and 3 are cross-sectional views of the device, FIGS. 4 and 5 are cross-sectional views and development views of a fixed cylinder, and FIGS. 6 and 7.
FIG. 4A is a side view, a front view and a rear view of a cylindrical cam.

As shown in FIGS. 1 and 2, this lens driving device has a low-pass filter 1 having a substantially rectangular contour.
1. A base 10 to which a CCD 12 or the like as an image pickup device is attached, a fixed barrel 20 fixed to the base 10, a cylindrical cam 30 rotatably and linearly supported inside the fixed barrel 20, and an optical axis inside the cylindrical cam 30. Drive for driving the first lens group 40 and the second lens group 50 movably supported in the direction L, the third lens group 60 movably supported in the optical axis direction L with respect to the base 10, and the cylindrical cam 30. A mechanism 70, a drive mechanism for driving the third lens group 60, and the like are provided.

As shown in FIGS. 1 to 3, the fixed barrel 20 as a cam member is formed in a cylindrical shape having an axis in the optical axis direction L and is fixed to the base 10. Fixed cylinder 20
As shown in FIGS. 4 and 5, on the inner peripheral surface of the, three cam grooves 21 arranged at equal intervals, three retaining walls 22, and stoppers arranged continuously to one retaining wall 22. 23
Etc. are provided.

The three cam grooves 21 exert a cam action on three cam followers 31, which will be described later. The three retaining walls 22 prevent the cam follower 31 from falling rearward from the cam groove 21 in the optical axis direction L. The stopper 23 restricts relative rotation (movement) of the cylindrical cam 30 with respect to the fixed cylinder 20 by contact with a contact piece 32 described later.

The stopper 23 and the abutment piece 32 have a terminal end portion 21e of the cam groove 21, as indicated by reference numeral 31 '' in FIG.
Slightly before the cam follower 31 collided with
In the direction of R1
It is formed so as to regulate the rotation to. That is,
The stopper 23 and the abutment piece 32 function as a restricting unit that restricts the rotation of the cylindrical cam 30 with respect to the fixed cylinder 20 before the cam follower 31 reaches the terminal end 21e of the cam groove 21. Before the cam follower 31 reaches the terminal end portion 21e, the state in which the cam follower 31 is in contact with the wall surface of the terminal end portion 21e is included as long as it can prevent the cam follower 31 from riding on the cam groove 21.

The cylindrical cam 30 as a follower member is formed in a cylindrical shape and is coaxially arranged inside the fixed barrel 20 as shown in FIGS. 2, 3, 6, and 7. On the outer peripheral surface of the cylindrical cam 30, as shown in FIGS. 6 and 7, three pin-shaped cam followers 31, which are arranged at equal intervals,
An abutting piece 32 as an L-shaped restricting member protruding outward in the radial direction, an arc gear 33, and the like are formed.

On the inner peripheral surface of the cylindrical cam 30, the cam groove 3 exerting a cam action on the first lens group 40 and the second lens group 50.
4, 35 are formed, and a guide cylinder 35 that guides in the optical axis direction L is arranged while restricting the rotation of the first lens group 40 and the second lens group 50. The three cam followers 31 are inserted into the three cam grooves 21 of the fixed barrel 20, and the cylindrical cam 30 is rotated by the drive mechanism 70 to move forward and backward by itself in the optical axis direction L. First lens group 40 and second lens group 5
Variable magnification driving is performed by moving 0 in the optical axis direction L.

As shown in FIGS. 2 and 3, the first lens group 40 includes a lens holding frame 41 for holding the lens G1, and three cam followers 42 (to be further referred to as “cam followers 42” formed in the lens holding frame 41 and inserted into the cam grooves 34). , One is omitted in FIG. 3) and the like. Then, the first lens group 40 moves forward and backward in the optical axis direction L by the rotation of the cylindrical cam 30.

As shown in FIGS. 2 and 3, the second lens group 50 includes a lens holding frame 51 for holding the lens G2, and three cam followers 52 (which are formed in the lens holding frame 51 and inserted in the cam grooves 35). , One is omitted in FIG. 3),
A shutter unit S fixed to the lens holding frame 51 and the like are provided. The second lens group 50 includes the cylindrical cam 3
By the rotation of 0, it moves forward and backward in the optical axis direction L.

As shown in FIGS. 2 and 3, the third lens group 60 includes a lens holding frame 61 for holding the lens G3. The lens holding frame 61 is driven by a drive mechanism including a motor 81 arranged outside the fixed barrel 20, a lead screw driven by the motor 81, a nut held by the lens holding frame 61 and screwed into the lead screw, and the like. Direction L
In, the focusing operation is performed by moving forward and backward.

As shown in FIGS. 2 and 3, the drive mechanism 70 includes a motor 71 fixed to the base 10, a worm 72 fixed to its drive shaft, and a worm wheel 73 supported by the base 10 and meshing with the worm 72. A worm wheel 74 integrally formed coaxially with the worm wheel 73, a worm wheel 75 supported by the base 10 and meshing with the worm wheel 74, a gear wheel 76 integrally formed with the worm wheel 75 coaxially, and the base 10. It is formed by a gear 76 supported and meshed with the gear 76 and the arc gear 33.

That is, when the motor 71 rotates, the cylindrical cam 30 as a follower member is transferred to the fixed cylinder 20 as a cam member via the worm 72, the worm wheel 73, the worm 74, the worm wheel 75, the gear 76, and the gear 77. Rotate relative to each other. Then, the first lens group 40 and the second lens group 50 are extended (advanced) or extended (retracted) in the optical axis direction L, for example, from the telephoto end shooting position to the wide-angle view shown in FIG. It can be moved up to the edge photographing position and moved to a desired zoom position so that a wide range of photographing can be performed.

Next, a general operation when the above lens driving device is mounted on a digital camera will be described. First, in the retracted state of non-shooting, the first lens group 4
The 0 and second lens groups 50 are in the retracted position retracted rearward in the optical axis direction L. At this time, the cam follower 31
Is located at a position indicated by reference numeral 31 ′ in FIG. 5 with respect to the cam groove 21, and is not in contact with the other end of the cam groove 21. That is, the stopping position (collapsed position) on the retracting side of the cylindrical cam 30 is determined by another restricting means (not shown).
It is regulated by. Further, the contact piece 32 is located at a position indicated by reference numeral 32 ′ in FIG. 5, and is located at a position separated from the stopper 23 of the fixed barrel 20 and the retaining wall 22.

When the cylindrical cam 30 is rotated by the drive mechanism 70 from this collapsed state, the cam follower 31 is guided and moved by the cam groove 21, and the cylindrical cam 30 is extended forward in the optical axis direction L, and The rotation of the cylindrical cam 30 causes the cam followers 42, 52 to move in the cam grooves 34,
Under the guidance of 35, the first lens group 40 and the second lens group 50 first move to the telephoto end shooting position, and subsequently reach the wide-angle end shooting position, which is the maximum payout position, as shown in FIG. On the other hand, the third lens group 60 includes a drive mechanism (motor 8
1 etc.), the first lens group 40 and the second lens group 50
It moves to the in-focus position according to the position of.

In this feeding operation, when the first lens group 40 and the cylindrical cam 30 approach the maximum feeding position, the contact piece 32 contacts the stopper 23 before the cam follower 31 reaches the terminal end 21e of the cam groove 21. The two approaches and come into contact with each other (the position indicated by reference numeral 32 ″ in FIG. 5). By this contact, the cylindrical cam 30 is positioned at the maximum feeding position.

As described above, the contact piece 32 is previously attached to the stopper 2
3, the cam follower 31 is prevented from excessive movement by contacting the cam follower 3. Therefore, even if the driving force of the drive mechanism 70 is large, the cam follower 31 can be prevented from riding on the cam groove 21 and biting in or falling out. Therefore, a reliable driving operation can be obtained.

Further, in the driving force transmission path transmitted from the fixed cam 20 through the cylindrical cam 30 to the lens holding frames 41, 51, the cylindrical cam 30 is preliminarily over-rotated by the restricting means (the stopper 23, the contact piece 32). Because of the restriction, in the relationship between the cam followers 42, 52 of the lens holding frames 41, 51 and the cam grooves 34, 35 of the cylindrical cam 30, it is necessary to prevent the cam followers 42, 52 from coming off without providing a restricting means. Therefore, a reliable driving operation can be obtained.

In the above embodiment, the cylindrical cam 3 as a follower member is provided inside the fixed cylinder 20 as a cam member.
In the lens driving device in which 0 is provided and a plurality of lens groups 40 and 50 are further provided inside the cylindrical cam 30, the configuration according to the present invention is adopted, but the present invention is not limited to this, and The configuration according to the present invention may be adopted in a configuration in which one lens group is directly held and the cylindrical cam 30 functions as a lens holding frame.

Further, in the above-mentioned embodiment, the fixed barrel 2 is used as the restricting means at the maximum extension position of the lens.
Although 0 (cam member) and the relative movement of the cylindrical cam 30 (follower member) are regulated, the relative movement of both is regulated at the maximum retracted position (collapsed position) of the lens. Good.

[0032]

As described above, according to the lens driving device of the present invention, a cam member (fixed cylinder) having a cam groove that cams in the optical axis direction, and a lens is held and inserted into the cam groove. A follower member (cylindrical cam) having a cam follower guided and guided, the regulating means for regulating relative movement between the cam member and the follower member is provided before the cam follower reaches the end portion of the cam groove. As a result, the relative movement of the cam follower and the cam follower is restricted before the cam follower reaches the end portion of the cam groove during variable-magnification driving, so that a collision between the cam follower and the end portion of the cam groove is avoided. Therefore, even if the driving force is large,
The cam follower is prevented from falling out of the cam groove, and a reliable drive operation is performed.

[Brief description of drawings]

FIG. 1 is a front view showing an embodiment of a lens driving device according to the present invention.

FIG. 2 is a developed sectional view showing an embodiment of a lens driving device according to the present invention.

FIG. 3 is a vertical cross-sectional view showing a state in which a cylindrical cam and a lens holding frame (lens) are at a maximum extended position.

FIG. 4 is a cross-sectional view showing a fixed cylinder as a cam member.

FIG. 5 is a development view showing an inner peripheral surface of a fixed barrel.

6A and 6B show a cylindrical cam as a follower member, FIG. 6A is a side view showing an outer peripheral surface, and FIG. 6B is a front view.

FIG. 7 shows a cylindrical cam as a follower member, (a) is a side view showing an outer peripheral surface, and (b) is a rear view.

[Explanation of symbols]

10 base 20 Fixed cylinder (cam member) 21 Cam groove 22 retaining wall 23 Stopper (Regulator) 30 Cylindrical cam (follower member) 31 Cam Follower 32 Abutment piece (regulating means) 33 Arc gear 34, 35 cam groove 40 First lens group G1 lens 41 Lens holding frame 42 Cam Follower 50 Second lens group G2 lens 51 Lens holding frame 52 Cam Follower 60 Third lens group G3 lens 61 Lens holding frame 70 Drive mechanism 71 Motor (drive source) 72,74 Warm 73,75 Worm wheel 76,77 gears 81 Motor (drive mechanism) L optical axis direction

Claims (4)

[Claims] 1. A cam member having a cam groove that makes a cam action in the optical axis direction, and a follower member having a cam follower that holds a lens and is guided by being inserted into the cam groove. A lens driving device for moving the lens in the optical axis direction by relatively moving the follower member, wherein the cam member and the follower member are provided before the cam follower reaches an end portion of the cam groove. A lens driving device, characterized in that a regulating means for regulating the relative movement of the both is provided. 2. The regulating means is formed so as to regulate the relative movement of the cam member and the follower member at the maximum feeding position of the lens. Lens drive device. 3. A base, a fixed barrel which is fixed to the base and has an axis in the optical axis direction, and a lens holding frame which supports the lens inside the fixed barrel so as to be reciprocally movable in the optical axis direction. And a drive source for driving the lens holding frame, the cam member is the fixed cylinder having the cam groove formed on an inner peripheral surface thereof, and the follower member is the lens holding frame having the cam follower formed therein. The restricting means comprises a stopper formed to project on the inner peripheral surface of the fixed barrel, and an abutting piece formed on the lens holding frame and capable of abutting the stopper. Item 3. The lens driving device according to item 1 or 2. 4. A base, a fixed barrel which is fixed to the base and has an axis in the optical axis direction, and which is supported inside the fixed barrel so as to be retractable in the optical axis direction with respect to the fixed barrel and has a cam action. A cylindrical cam having a plurality of lenses, a plurality of lens holding frames that hold the lens and that are arranged inside the cylindrical cam and are moved in the optical axis direction by the cam action of the cylindrical cam, and a driving source that applies a rotational driving force to the cylindrical cam. And the cam member is the fixed cylinder having the cam groove formed on the inner peripheral surface thereof, the follower member is the cylindrical cam having the cam follower formed on the outer peripheral surface thereof, and the regulating means is 3. The stopper according to claim 1 or 2, further comprising: a stopper formed so as to project on an inner peripheral surface of the fixed cylinder, and an abutment piece formed so as to protrude on an outer peripheral surface of the cylindrical cam and capable of contacting the stopper. The lens driving device described.