WO2005059616A1

WO2005059616A1 - Lens drive device

Info

Publication number: WO2005059616A1
Application number: PCT/JP2004/018798
Authority: WO
Inventors: Kenji Kawamura
Original assignee: Tokyo Micro Inc.
Priority date: 2003-12-19
Filing date: 2004-12-16
Publication date: 2005-06-30
Also published as: JPWO2005059616A1

Abstract

[PROBLEMS] To provide a lens drive device capable of moving a lens without rattling, vibration, and hysteresis by using an air-core stepping motor and allowed to reduce size. [MEANS FOR SOLVING PROBLEMS] This lens drive device (1) comprises the air-core stepping motor (20) having a stator (21) with a coil (25) and a magnet (23) rotatably stored in the stator (21). A lead screw (31) is formed in the inner surface of the magnet (23). In the magnet (23), the lens (L1) is axially movably guided by guide pins (41) and locked so as not to be rotated. A ball (37) brought into contact with the groove of the lead screw (31) and a screw member (35) formed of a spring (36) energizing the ball (37) toward the groove are installed in the holder (33) of the lens (L1). The lens (L1) can be guided by the guide pins (41) so as to be less vibrated in the radial direction, and the swing in the radial direction and the rattling in the optical axis direction of the magnet (23) and a screw feed mechanism can be absorbed by the screw member (35).

Description

Specification

Lens drive

Technical field

The present invention relates to an apparatus for driving a lens using an air-core stepping motor. In particular, the present invention relates to a lens driving device of a small-sized image pickup device equipped with an auto-focus and zoom mechanism, which is mounted on a mobile phone, a video camera, a camera, and the like.

Background art

[0002] As a device for driving a lens in an optical axis direction in a rotor of an air-core stepping motor, for example, there is one disclosed in Patent Document 1.

[0003] Patent Document 1: JP-A-60-416

Disclosure of the invention

Problems to be solved by the invention

[0004] However, it is considered that the lens driving device disclosed in the above-mentioned document does not take measures against vibration of the motor rotor and backlash of the lens driving mechanism. Therefore, it is considered that problems such as image blurring of the lens or hysteresis occur.

[0005] The present invention has been made in view of the above problems, and provides a lens driving device that can move a lens without backlash and hysteresis using an air-core stepping motor and that can be downsized. The purpose is to provide.

Means for solving the problem

[0006] A lens driving device of the present invention is an air-core stepping motor having a cylindrical stator including a coil, and a cylindrical rotor rotatably housed in the stator. And a lens provided movably in the axial direction in (1), wherein the lens is guided movably in the axial direction between the stator or a member to which the stator is fixed and the lens. And a guide member for preventing rotation is provided. A lead screw is formed on the inner surface of the magnet of the rotor or a hollow member attached to the magnet. A screw member that is flexibly urged into the groove is provided. It is characterized by. Note that the screwing member does not have to be urged flexibly into the groove of the screw.

[0007] By providing the above-described guide member, the lens can be guided so as to be less likely to swing in the radial direction (radial direction). Further, by providing the above-mentioned screwing member, it is possible to absorb radial deflection of the magnet-screw feed mechanism and play in the optical axis direction (thrust direction). For this reason, it is possible to prevent image blurring that tends to cause blurring, backlash, and hysteresis in the lens.

In the present invention, if the lead screw is formed directly on the inner periphery of the magnet of the rotor, the configuration of the device can be simplified.

[0009] In the present invention, the screw member force may be a ball applied to the screw groove, and an elastic member for urging the ball into the screw groove.

[0010] In the present invention, an axially extending pin is provided upright on the rotor, and the stator or a member to which the stator is fixed has an annular groove slidable by fitting the pin. It can be formed. In this case, since the pins and grooves serve as bearings for the rotor, the magnet can be rotatably supported on the frame member by a simple mechanism. The annular groove may be a step instead of a groove. For example, if there are a plurality of pins, the inside or outside of the pins can be guided on the circumferential surface by a step, so as to act as a bearing for the rotor.

At this time, if a thrust damper is attached to the base of the pin, the thrust of the lens in the thrust direction can be eliminated by holding the thrust in the thrust direction.

In the present invention, it is preferable that a magnetic bearing that rotatably supports the rotor is further provided between the rotor and the stator or a member to which the stator is fixed.

[0012] The magnetic bearings can support the rotor S in a non-contact manner with respect to the stator or a member to which the stator is fixed. Therefore, it is possible to maximize the motor output without bearing hysteresis. Further, since no sliding noise of the bearing is generated, noise can be reduced.

[0013] Further, the magnetic bearing is provided on a permanent magnet provided on the outer circumference and Z or end of the rotor, and on the inner circumference and Z or end of the stator or a member to which the stator is fixed. Re, preferably formed in pairs with permanent magnets.

[0014] By magnetizing the opposing surfaces of each permanent magnet to the same polarity, a magnetic repulsion is generated. With this magnetic repulsion, the rotor can be held in non-contact with the stator or the member to which it is fixed. If bearings are arranged at both axial ends of the rotor so as to generate magnetic repulsion in the thrust direction and the radial direction, the rotor can be held in a well-balanced manner.

[0015] Further, it is preferable that a back yoke layer is provided on the back and side surfaces of the permanent magnet.

When the load on the motor increases due to the weight of the rotor (the weight of the lens and lens holder), a large magnetic repulsion is required. Therefore, by providing a back yoke layer on the back and side surfaces of the permanent magnet, the magnetic repulsion can be increased.

[0016] Another lens driving device of the present invention is an air-core steering motor having a cylindrical stator including a coil, and a cylindrical rotor including a magnet rotatably housed in the stator. And a lens movably provided in the rotor in the axial direction, wherein the rotor is rotated between the rotor and the stator or a member to which the stator is fixed. It is characterized by having a magnetic bearing for supporting.

[0017] Since the rotor can be rotatably supported by the magnetic bearing in a non-contact manner, it is possible to provide a highly efficient lens driving device capable of maximally utilizing the output of the motor. Further, since no sliding noise of the bearing is generated, a low-noise lens driving device can be provided.

The invention's effect

As is apparent from the above description, according to the present invention, the backlash and runout in the radial and thrust directions caused by the rotation of the magnet are absorbed by the screw member. For this reason, the backlash does not propagate to the lens, and the optical performance such as image blur does not deteriorate when the lens is driven. In addition, since the backlash and runout in the radial and thrust directions can be prevented by the screw member while supporting the magnet with a simple mechanism, the cost of the lens driving device can be reduced.

BEST MODE FOR CARRYING OUT THE INVENTION

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

(First embodiment) FIG. 1 is a diagram illustrating a lens driving device according to a first embodiment of the present invention. FIG. 1 (A) is a side sectional view, and FIG. 1 (B) is a front view.

FIG. 2 is a diagram showing the inside of the lens driving device of FIG.

The lens driving device 1 includes a cylindrical fixed frame 10, an air-core stepping motor 20 fixed to the frame 10, and a moving lens L 1 driven in the fixed frame 10 in the axial direction by the motor 20. Prepare. A fixed lens L2 is attached to one opening of the fixed frame 10. By moving the movable lens L1 in the optical axis direction with respect to the fixed lens L2, a zoom operation and a focus operation are performed.

The fixed frame 10 includes a pair of frame members 11 and 12. Each frame member is a ring-shaped member having the same shape. At the center of each of the frame members 11 and 12, openings 13 and 14 are opened centered on the optical axis OA of the lens. Each member 11, 12 has a circular flange portion l la, 12a, an annular side wall l lc, 12c provided inward of the outer periphery of the flange portion, and an inner portion formed between the flange portion and the side wall. It has a shoulder l lb, 12b. Each part has a concentric shape centered on the optical axis OA of the lens.

A fixed lens L2 is fixed to an opening 13 of one of the frame members 11 (right side in the figure). The fixed lens L2 is fitted into the inner step l ib of the frame member 11, and is fixed to the frame member 11 by being applied to the outer peripheral portion of the lens L2 and the end face of the S flange portion 11a. The opening (14) of the frame member 12 on the other side (left side in the figure) is open with nothing in it.

The frame members 11 and 12 of the fixed frame 10 face each other such that the flange portions la and 12a are on the outside. Further, the stepping motor 20 is disposed between the inner steps l lb, 12 b of the frame members 11, 12 and the side walls l lc, 12 c. The motor 20 has a cylindrical stator 21 and a cylindrical rotor 23 rotatably housed in the stator 21. The stator 21 and the rotor 23 are fitted in a concentric cylindrical shape, and are arranged coaxially with the optical axis OA of the lens. The stator 21 has two rows of stator pieces 21A and 21B arranged in the axial direction, a coil 25 and a yoke 27. A groove having a U-shaped cross section is formed on the outer peripheral surface of each of the stator pieces 21A and 21B. Each coil 25A, 25B is accommodated in each groove. The yoke 27 is cylindrical and covers the outside of each of the stators 21A and 21B. Both ends of the yoke 27 are curved inward so as to surround the stator pieces 21A and 21B. Both ends of the yoke 27 are connected to the frame members 11, 12 The side wall llc, sandwiched between the end faces of 12c, is fixed to the same wall llc, 12c. The outer peripheral surface of the yoke 27 is a part of the side surface of the lens driving device 1.

The rotor 23 is a cylindrical member made of a plastic magnet. Alternatively, another member is joined to the magnet. The rotor 23 is fitted in the hollow portion of the stator 21 concentrically with the stator 21 and is rotatably supported by the fixed frame 10 by two bearings 29A and 29B. Each bearing 29 is arranged outside both ends of the stator 21, the outer ring is fixed to the side walls 11, 12 c of each frame member 11, 12 and the inner peripheral surface of the yoke 27, and the inner ring is fixed to the outer peripheral surface of both ends of the magnet 23. Fixed. There is a gap between the outer surface of the rotor (hereinafter referred to as a magnet) 23 and the inner surface of the stator 21. Also, a gap is opened between both end surfaces of the magnet 23 and the bearing 29 and the end surfaces of the inner steps l lb and 12b of the frame members 11 and 13. On the inner surface of the magnet 23, a lead screw 31 that advances in the optical axis direction is formed. The cross-sectional shape of the lead screw 31 is V-shaped.

The lens L 1 is arranged inside the hollow part of the magnet 23. A holder 33 is fixed to the outer edge of the lens L1. As is clearly shown in FIG. 2, the holder 33 is a ring-shaped member, and is formed by forming protrusions 34 extending in the radial direction of the lens from a plurality of locations (three in this example) on the outer periphery. The projections 34 are arranged at predetermined angles (in this example, 120 °) around the optical axis OA (lens center line). The outer surface of each projection 34 is provided with a hole extending in the radial direction of the lens. A screw member 35 screwed into the lead screw 31 of the magnet 23 is accommodated in this hole. The screw member 35 includes a spring 36 housed in a hole of the projection 34 of the holder 33, and a ball 37 disposed at the tip of the spring 36. A part of the ball 37 protrudes from the hole, and is urged toward the groove of the lead screw 31 by a spring 36 to be screwed into the groove. Further, a through hole 39 parallel to the optical axis direction is formed at the base of each protrusion 34.

Note that the shape of the holder 33 is actually a shape that is twisted along the shape of one lead screw 31.

As shown in FIG. 1 (A), three guide pins 41 are stretched between the end faces of the opposed inner steps l lb and 12b of the frame members 11 and 12 of the fixed frame 10. I have. Both ends of each pin 41 are fitted into holes lx, 12x formed in the end faces of the inner steps lib, 12b. Each guide pin 41 It is parallel to the optical axis OA and is arranged at an equal center angle (120 °) with respect to the optical axis OA. Each guide pin 41 penetrates through the through hole 39 of the projection 34 of the lens holder 33, and the holder 33 moves bidirectionally on each guide pin 41 in the optical axis direction. Thereby, the lens L1 moves bidirectionally in the optical axis direction.

[0025] A lens driving method of the lens driving device 1 will be described.

When the coil 21 of the stator 21 is energized and the stator 21 is excited, the magnet 23 rotates around the optical axis OA. When the magnet 23 rotates, the holder 33 screwed to the lead screw 31 of the magnet 23 via the screw member 35 is sent along the lead screw 31 in the optical axis direction. At this time, the holder 33 is not rotated because it is stopped by the guide pin 41, but the ball 37 of the screw member 35 rolls or slides in the groove of the lead screw 31 while sliding along one side wall of the groove. Pushed in the direction. Therefore, the lens L1 moves in the optical axis direction while maintaining the initial posture. By changing the direction of the current supplied to the coil 25, the lens L1 moves in the optical axis direction in both directions.

As described above, when driving the stepping motor 20, the magnet 23 as a rotor is supported by the bearing 29 and is rotating. At this time, due to the accuracy of the bearing 29, the runout accuracy of the magnet, and the like, a runout in the lens radial direction (radial direction) and backlash in the optical axis direction (thrust direction) occur in the magnet 23.

[0027] In the lens driving device 1, as described above, since the size of the gap between the guide pin 41 and the lens holder 33 is relatively small, the lens L1 does not swing too much in the radial direction. Can move up. Further, the vibration in the radial direction is absorbed by the screw member 35. That is, the backlash (runout, eccentricity) of the magnet 23 as the rotor is transmitted from the ball 37 of the screw member 35 to the spring 36 and absorbed by the spring 36, so that it is not transmitted to the lens L1. . Further, since the ball 37 is urged toward the groove of the screw 31 by the spring 36, the surface of the ball 37 in the thrust direction (optical axis direction) always hits both side walls of the groove. For this reason, the ball 37 cannot move in the groove in the thrust direction, and the backlash of the holder 33 in the thrust direction can be prevented. In this way, backlash and backlash are suppressed, and no backlash, backlash or hysteresis occurs in the radial and thrust directions. Therefore, the zoom function and the focus function can be performed without deteriorating optical performance such as image blur of the lens. (Second embodiment)

FIG. 3 is a diagram illustrating a lens driving device according to a second embodiment of the present invention. FIG. 3 (A) is a side sectional view, and FIG. 3 (B) is a front view.

The lens driving device 61 of this example has substantially the same configuration as the lens driving device 1 of FIG. 1, but differs in the method of supporting the magnet 23 of the stepping motor 20. Note that, in FIG. 3, components and members having the same configuration and operation as those of the lens driving device in FIG. 1 are denoted by the same reference numerals as in FIG. 1, and description thereof will be omitted.

[0029] In the stepping motor 20 of this example, both end face forces of the magnet 23 and the bearing pins 63A and 63B are erected. Each bearing pin 63 is arranged parallel to the optical axis direction and distributed around the optical axis 〇A. The bearing pin 63A on the fixed lens side stands upright from the magnet 23 via the thrust damper 65. The thrust damper 65 urges the bearing pin 63 in the thrust direction (optical axis direction), and for example, a panel (coil, plate), rubber (cushion material), or the like can be used.

The number of the bearing pins 63 is plural.

An annular groove 67 into which the above-mentioned bearing pin 63 is fitted is formed on the end face of the step portion l lb, 12b of each of the fixed frame members 11, 12. The width of each groove 67 is a dimension obtained by adding a predetermined clearance to the diameter of the bearing pin 63. By fitting each bearing pin 63 of the magnet 23 into the groove 67, the magnet 23 is rotatably supported by the fixed frame 10. That is, a bearing pin 63 and a groove 67 are provided instead of the bearing 29 of the lens driving device in FIG. When the magnet 23 rotates around the optical axis OA during operation of the stepping motor, each bearing pin 63 moves while sliding in the groove 67 of each of the fixed frame members 11 and 12.

In this example, the magnet 23 is supported by a simple mechanism such as the pin 63 and the groove 67. In such a method, backlash in the magnet 23 is more likely to occur than in the supporting method using the bearings shown in FIG. The radial deflection and eccentricity are absorbed by the screw member 35. The play in the thrust direction is suppressed by urging the ball 37 of the screw member 35 into the groove of the lead screw 31 of the rotor 123 by the spring 36. Further, the play in the thrust direction is absorbed by the thrust damper 65. In this example, a bearing is used to support the magnet 23. Since the configuration of the rotation support mechanism of the magnet 23 is simplified without using the magnet, the cost can be reduced.

[0032] The annular groove 67 may be a step instead of a groove. For example, as three or more pins 63, if the inside or outside of the pins is guided on the circumferential surface by a step, the function of bearing the magnet 23 is achieved.

[0033] (Third embodiment)

FIG. 4 is a view for explaining a lens driving device according to a third embodiment of the present invention. FIG. 4 (A) is a side sectional view, and FIG. 4 (B) is a front view.

The lens driving device 71 of this example has substantially the same configuration as the lens driving device of FIG. 1, but differs in the method of supporting the magnet 23 of the stepping motor 20. Note that, also in FIG. 3, components and members having the same configuration and operation as those of the lens driving device in FIG. 1 are given the same reference numerals as in FIG. 1, and descriptions thereof are omitted.

[0034] The magnet 23 of the stepping motor 20 of this example is supported by bearing pins 63 on the fixed lens side in the same manner as the lens driving device of Fig. 2, and is supported by balls 73 on the opening side.

A bearing pin 63 stands on the fixed lens side end surface of the magnet 23 via a thrust damper 65. Each bearing pin 63 is distributed around the optical axis OA. An annular groove 67 into which the bearing pin fits is formed on the end face of the step portion ib of the frame member 11 on the fixed lens side. By fitting each bearing pin 63 of the magnet 23 into this groove 67, the fixed lens side end of the magnet 23 is rotatably supported by the fixed frame 10.

On the other hand, an annular groove 23 a is formed on the outer peripheral surface of the end of the magnet 23 on the fixed frame opening side. The shape of the annular groove 23a is V-shaped and has a bottom wall and side walls inclined outward from both sides of the bottom wall. The side wall 12c of the fixed frame member 12 on the opening side is formed with a flange 12d projecting inward. A V-shaped annular groove 12e is also formed on the inner peripheral surface of the collar portion 12d at a position facing the annular groove 23a of the magnet 23. A plurality of balls 73 are interposed between the annular groove 23a of the magnet 23 and the annular groove 12e of the flange 12d of the frame member 12. In this manner, at the opening end of the magnet 23, the magnet 23 is rotatably supported by the fixed frame 10 by the plurality of balls 73 sandwiched between the grooves 23a and 12e. Has been.

[0036] Also in this example, the magnet 23 is supported by a simpler method than the lens driving device of Fig. 1, and cost reduction can be achieved. Further, in the supporting method using the bearing pin 61 and the groove 67, friction between the outer surface of the pin 63 and the side surface or the end surface of the groove 67 may occur, and a load may be applied to the motor 20 when the magnet rotates. Therefore, by supporting one end of the magnet 23 through the ball 73 having a small coefficient of friction, it is possible to reduce the force applied to the motor 20 where friction is less likely to occur.

(Fourth embodiment)

FIG. 5 is a diagram illustrating a lens driving device according to a fourth embodiment of the present invention. FIG. 5 (A) is a side sectional view, and FIG. 5 (B) is a part of FIG. 5 (A). The enlarged view, Figure 5 (C), is a front view.

The lens driving device 201 of this example also differs from the lens driving device of FIG. 1 in the structure and support method of the rotor of the 1S stepping motor and the structure and support method of the lens holder of the stepping motor. Components having the same configuration and operation as those of the lens driving device of FIG. 1 are denoted by the same reference numerals as in FIG. 1, and description thereof is omitted. The lens driving device of this example includes only the moving lens L1.

First, the structure and the supporting method of the rotor of the stepping motor will be described.

The rotor 80 of the stepping motor 20 in this example has a cylindrical rotor magnet 81 formed by molding or cutting a resin material (for example, a sliding grade POM-MS〇2 or the like). Sleeve) 83 attached. The sleeve 83 has a concentric cylindrical shape with the stator 21, and the rotor magnet 81 is fixed to the outer peripheral surface by bonding, outsert molding, or the like. A lead screw 85 that advances in the optical axis direction is formed on the inner peripheral surface of the sleeve 83. The cross-sectional shape of the lead screw 85 is substantially U-shaped. The sleeve 83 has a divided structure so that the rotor magnet 81 can be incorporated.

The sleeve 83 is rotatably supported by the fixed frame 10 by magnetic bearings 101 and 103. The two magnetic bearings 101 support both ends of the rotor 80 in the thrust direction in a non-contact manner with respect to the fixed frame 10. The two magnetic bearings 103 support both ends of the rotor 80 in a radial direction in a non-contact manner with respect to the fixed frame 10. As shown in an enlarged manner in FIG. 5B, the thrust bearing 101 includes a pair of permanent magnets 101S and 101R. One permanent magnet 101R is embedded along the outer periphery of the end face of the sleeve 83 and fixed by bonding or the like. The other permanent magnet 101S is embedded in the inner surface of the flange portion 11a of the frame member 11 facing the permanent magnet 101R, and is fixed by bonding or the like. Opposing surfaces of the permanent magnets 101R and 101S are magnetized so as to have the same polarity (N pole in this example). The permanent magnets 101R and 101S may be ring-shaped or divided chip-shaped and may be attached along the circumferential surface. Chip-shaped objects are easier to magnetize.

The radial bearing 103 includes a large-diameter permanent magnet 103S and a small-diameter permanent magnet 103R.

The small-diameter permanent magnet 103R is carried along the outer periphery of the end of the sleeve 83, and is fixed by bonding or the like. The large-diameter permanent magnet 103S is embedded in the inner surface of the step portion lib of the frame member 11 facing the small-diameter permanent magnet 103R, and is fixed by bonding or the like. Opposing surfaces of the permanent magnets 103R and 103S are magnetized so as to have the same polarity (N pole in this example). The permanent magnets 103R and 103S may be ring-shaped or divided chip-shaped and may be attached along the circumferential surface. Chips are easier to magnetize

With such a structure, in the thrust direction, the rotor 80 is held in non-contact with the fixed frame 10 by the magnetic repulsion of the opposing surface of each permanent magnet 101. Further, even in the radial direction, the rotor 80 is held in non-contact with the fixed frame 10 by the magnetic repulsion of the opposing surface of each magnet 103.

Therefore, since the rotor 80 can be held against the fixed frame 10 in a non-contact manner, the motor output without bearing hysteresis can be used to the maximum. Also, noise is reduced because no bearing sliding noise is generated.

As the permanent magnets 101 and 103 used for the bearing, for example, a neodymium magnet or a rare earth magnet can be used. The material, magnetic force, thickness, spacing between magnets, etc. of each permanent magnet depends on the specifications of the stepping motor (number of rotations, rotation speed, etc.), motor size and weight, load (weight of lens and lens holder), etc. Adjust accordingly.

Next, a structure and a supporting method of the lens holder 90 will be described. Also in this example, the lens holder 90 moves in both directions in the optical axis direction on the guide pin 41 which is parallel to the optical axis OA and is disposed at a center angle (120 °) equal to the optical axis OA. You. However, the two guide pins 41 also pass through a groove 91 that extends in the radial direction also on the outer peripheral surface of the lens holder 90. The remaining one guide pin passes through a through hole 93 formed in the lens holder 90 and extending in the optical axis direction. With such a structure, a part manufacturing error and an assembly error can be escaped.

A threaded portion 95 is provided on a part of the outer periphery of the lens holder 90. A hole extending in the radial direction of the lens is formed on the outer surface of the screw portion 95. A screw member (pin) 97 that is screwed into the lead screw 85 of the sleeve 83 is accommodated in this hole. The screw member 97 is screwed with a clearance that allows the run-out of the lead screw 85 of the sleeve 83 and the rotor 80 and the like. With such a structure, the lens holder 90 supported by the through hole 93 can be moved without being affected by the swing of the force rotor 80 and the like.

FIG. 6 is a view showing a modification of the lens driving device of FIG. 5, in which FIG. 6 (A) is a side sectional view, and FIG. 6 (B) is a partially enlarged view of FIG. 6 (A). .

In the lens driving device 201 shown in FIG. 5, when the weight of the rotor 80 (the lens L1 and the sleeve 83) is heavy, a bearing having a strong repulsive force is used to support the rotor 80 in a non-contact manner with respect to the fixed frame 10. Is required. In this case, back yokes 102 and 104 made of a magnetic material (for example, pure iron (SUYP) or iron (SECP)) are provided on the back and side surfaces of each permanent magnet of each bearing 10 軸受 and 103 '. By providing such back yokes 102 and 104, magnetic lines of magnetic force can be concentrated and a high magnetic repulsion can be obtained.

Brief Description of Drawings

FIG. 1 is a view for explaining a lens driving device according to a first embodiment of the present invention, wherein FIG. 1 (Α) is a side sectional view and FIG. 1 (B) is a front view.

FIG. 2 is a diagram showing the inside of the lens driving device of FIG. 1.

FIG. 3 is a view for explaining a lens driving device according to a second embodiment of the present invention. FIG. 3 (Α) is a side sectional view, and FIG. 3 (B) is a front view.

FIG. 4 is a view for explaining a lens driving device according to a third embodiment of the present invention. FIG. 4 (Α) is a side sectional view, and FIG. 4 (B) is a front view. FIG. 5 is a diagram illustrating a lens driving device according to a fourth embodiment of the present invention. FIG. 5 (A) is a side sectional view, and FIG. 5 (B) is a portion of FIG. 5 (A). The enlarged view, FIG. 5 (C) is a front view.

6 is a view showing a modification of the lens driving device of FIG. 5, where FIG. 6 (A) is a side sectional view and FIG. 6 (B) is a partially enlarged view of FIG. 6 (A).

Explanation of symbols

1 Lens drive

10 Fixed frame 11, 12 Frame member

11a, 12a Flange l ib, 12b Side wall

11c, 12c Inner stage l lx, 12x Shiso

12d collar 12e annular groove

13, 14 opening

20 Air core stepping motor 21 Stator

21A, 21B Stator piece 23 Rotor (magnet)

23A, 23B Magnet piece 23a Annular groove

25A, 25B Coinole 27 York

29A, 29B Bearing 31 Lead screw

33 Honoreda

34 Projection 35 Screw member

36 Panel 37 Ball

39 Through hole 41 Guide pin

61 Lens drive 63A, 63B Bearing pin

65 67 Groove

71 Lens drive 73 Ball

80-neck <_ and _one other _ 81 rotor magnet

83 Sleeve 85 Groove

90 Lens holder 91 Groove

93; fcis hole 95 threaded part

97 Screw member 101 Thrust bearing 103 Radial bearing

102, 104 Knock York

201 Lens drive

L1, L2 Lens OA Optical axis

Claims

The scope of the claims

[1] An air-core stepping motor having a cylindrical stator including a coil, and a cylindrical rotor including a magnet rotatably housed in the stator;

A lens provided axially movable in the rotor,

A lens driving device comprising:

A guide member is provided between the stator or a member to which the stator is fixed and the lens to guide the lens in an axially movable manner and to prevent the lens from rotating.

A lead screw is formed on an inner surface of the rotor magnet or a hollow member attached thereto,

A lens driving device, wherein a screwing member screwed with the lead screw and urged softly into a groove of the screw is provided on an outer edge of the lens.

[2] An air-core stepping motor having a cylindrical stator including a coil, and a cylindrical rotor including a magnet rotatably housed in the stator;

A lens provided axially movable in the rotor,

A lens driving device comprising:

A lens driving device, wherein a screw member for screwing with the lead screw is provided on an outer edge of the lens.

3. The lens driving device according to claim 1, wherein the lead screw is formed directly on an inner periphery of the magnet of the rotor.

4. The lens driving device according to claim 1, wherein the screwing member includes a ball applied to the screw groove, and an elastic member for urging the ball toward the screw groove. Place.

[5] An axially extending pin is erected on the rotor,

An annular slidable fitting of the pin with the stator or a member to which the stator is fixed. 5. The lens driving device according to claim 1, wherein a groove is formed.

6. The lens driving device according to claim 5, wherein a thrust damper is attached to a base of the pin.

7. The lens drive device according to claim 1, further comprising a magnetic bearing that rotatably supports the rotor, between the rotor and the stator or a member to which the stator is fixed.

[8] The magnetic bearing comprises a permanent magnet attached to the outer periphery and Z or end of the rotor, and a permanent magnet attached to the inner periphery and / or end of the stator or a member to which the stator is fixed. 8. The lens driving device according to claim 7, wherein the lens driving device is formed as a pair.

9. The lens driving device according to claim 8, wherein a back yoke layer is provided on a back surface and a side surface of the permanent magnet.

[10] An air-core stepping motor having a cylindrical stator including a coil, and a cylindrical rotor including a magnet rotatably housed in the stator;

A lens provided movably in the axial direction in the rotor,

A lens driving device comprising:

A lens driving device comprising: a magnetic bearing that rotatably supports the rotor between the rotor and the stator or a member to which the stator is fixed.