JPWO2005059616A1 - Lens drive device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a lens driving device that can move a lens without play, shake, or hysteresis by using an air-core stepping motor and can be miniaturized. A lens driving device includes an air-core stepping motor having a stator including a coil and a magnet that is rotatably accommodated in the stator. A lead screw 31 is formed on the inner surface of the magnet 23. The lens L1 is guided in the magnet 23 so as to be movable in the axial direction by the guide pin 41 and is prevented from rotating. The lens L1 holder 33 is provided with a threaded member 35 including a ball 37 applied to the groove of the lead screw 31 and a spring 36 that urges the ball 37 toward the groove. The guide pin 41 can guide the lens L1 so that it does not easily shake in the radial direction. [Selection] Figure 1

Description

  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 for a small-sized imaging device equipped with an autofocus and zoom mechanism, which is mounted on a mobile phone, a video camera, a camera, and the like.

  As an apparatus 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.

JP-A-60-416

  However, it is considered that the lens drive device of the above-mentioned document does not take measures to remove the shake of the motor rotor and the backlash of the lens drive mechanism. Therefore, it is considered that problems such as lens image blur or hysteresis occur.

  The present invention has been made in view of the above-described problems, and provides a lens driving device that can move a lens without backlash, vibration, and hysteresis using an air-core stepping motor and can be downsized. With the goal.

  The lens driving device of the present invention includes an air-core stepping motor having a cylindrical stator including a coil, and a cylindrical rotor including a magnet rotatably accommodated in the stator, and an axial direction in the rotor A lens driving device comprising: a lens provided movably, wherein the lens is guided between the stator or a member to which the stator is fixed and the lens so as to be movable in the axial direction, and the guide is configured to prevent rotation. A lead screw is formed on the inner surface of the rotor magnet or a hollow member attached thereto, and is screwed onto the outer edge of the lens with the lead screw and is flexible toward the groove of the screw. A screwing member urged by the screw is provided. In addition, the screwing member may not be urged flexibly toward the groove of the screw.

  By providing the above guide member, it is possible to guide the lens so that it does not easily shake in the radial direction (radial direction). Further, by providing the screwing member, it is possible to absorb radial shake and backlash in the optical axis direction (thrust direction) of the magnet and the screw feed mechanism. For this reason, shake, backlash, and hysteresis hardly occur in the lens, and image blurring can be prevented.

  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 apparatus can be simplified.

  In the present invention, the screwing member may include a ball applied to the screw groove and an elastic member that urges the ball toward the screw groove.

In the present invention, an axially extending pin is erected on the rotor, and an annular groove is formed on the stator or a member to which the stator is fixed so that the pin can be fitted and slid. Can be. In this case, since the pin and the groove serve as a bearing 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 inner side or the outer side of these pins can be guided on the circumferential surface by a step, thereby fulfilling the function of a rotor bearing.
At this time, if a thrust damper is attached to the base of the pin, the backlash in the thrust direction of the lens can be eliminated by maintaining the pressure in the thrust direction.

  In this invention, it is preferable to further provide the magnetic bearing which rotationally supports the said rotor between the said rotor and the said stator or the member to which it is fixed.

  The magnetic bearing can support the rotor in a non-contact manner with respect to the stator or the member to which it is fixed. For this reason, there is no hysteresis of a bearing and a motor output can be utilized to the maximum extent. Further, since no sliding noise of the bearing is generated, noise can be reduced.

  Furthermore, the magnetic bearing is a pair of a permanent magnet attached to the outer periphery and / 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. It is preferable that it is formed.

  A magnetic repulsive force is generated by magnetizing opposing surfaces of each permanent magnet to the same polarity. This magnetic repulsive force can hold the rotor in a non-contact manner with respect to the stator or the member to which it is fixed. Further, if the bearings are arranged at both ends of the rotor in the axial direction so as to generate a magnetic repulsive force in the thrust direction and the radial direction, the rotor can be held in a balanced manner.

Furthermore, it is preferable that a back yoke layer is provided on the back and side surfaces of the permanent magnet.
When the weight of the rotor (the weight of the lens and the lens holder) increases and the load on the motor increases, a large magnetic repulsive force is required. Thus, by providing a back yoke layer on the back and side surfaces of the permanent magnet, the magnetic repulsive force can be increased.

  Another lens driving device of the present invention includes an air-core stepping motor having a cylindrical stator including a coil, and a cylindrical rotor including a magnet rotatably accommodated in the stator, and in the rotor A lens driving device including a lens movably provided in an axial direction, comprising: a magnetic bearing that rotatably supports the rotor between the rotor and the stator or a member to which the stator is fixed. It is characterized by.

  Since the rotor can be rotationally supported in a non-contact manner by the magnetic bearing, it is possible to provide a highly efficient lens driving device that can make maximum use of the output of the motor. Further, since no bearing sliding noise is generated, a low noise lens driving device can be provided.

  As is apparent from the above description, according to the present invention, the backlash and vibration in the radial direction and the thrust direction due to the rotation of the magnet are absorbed by the screwing member. For this reason, backlash and shake are not transmitted to the lens, and optical performance such as image blurring does not deteriorate when the lens is driven. In addition, since the back and backlash and the shake in the radial direction and the thrust direction can be prevented by the screwing 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)
1A and 1B are diagrams for explaining a lens driving device according to a first embodiment of the present invention. FIG. 1A is a side sectional view and FIG. 1B 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 that is driven axially by the motor 20 inside the fixed frame 10. Prepare. A fixed lens L <b> 2 is attached to one opening of the fixed frame 10. By moving the moving lens L1 in the optical axis direction with respect to the fixed lens L2, a zooming action and a focusing action 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. In the center of each frame member 11, 12, an opening 13, 14 centered on the optical axis OA of the lens is opened. Each of the members 11 and 12 includes a circular flange portion 11a and 12a, an annular side wall 11c and 12c provided inside the outer periphery of the flange portion, and an inner step portion 11b formed between the flange portion and the side wall. , 12b. Each part has a concentric shape centered on the optical axis OA of the lens.
A fixed lens L2 is fixed to the opening 13 of the frame member 11 on the one side (right side in the figure). The fixed lens L2 is fitted into the inner step portion 11b of the frame member 11, and the outer peripheral portion of the lens L2 is fixed to the frame member 11 with the end face of the flange portion 11a being applied. The other (left side in the figure) of the frame member 12 is open without containing anything.

  The frame members 11 and 12 of the fixed frame 10 face each other so that the flange portions 11a and 12a are on the outside. The stepping motor 20 is disposed between the inner step portions 11b and 12b of the frame members 11 and 12 and the side walls 11c and 12c. The motor 20 includes a cylindrical stator 21 and a cylindrical rotor 23 that is rotatably accommodated in the stator 21. The stator 21 and the rotor 23 are fitted into a concentric cylinder 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 stator piece 21A, 21B. Each coil 25A, 25B is accommodated in each groove. The yoke 27 is cylindrical and covers the outside of each stator 21A, 21B. Both ends of the yoke 27 are curved inward so as to surround the stator pieces 21A and 21B. Both end surfaces of the yoke 27 are sandwiched between end surfaces of the side walls 11c and 12c of the frame members 11 and 12, and are fixed to the walls 11c and 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 into the hollow portion of the stator 21 in a concentric cylinder shape and is rotatably supported by the fixed frame 10 by two bearings 29A and 29B. Each bearing 29 is disposed outside both ends of the stator 21, the outer ring is fixed to the side walls 11 c and 12 c of the frame members 11 and 12, and the inner peripheral surface of the yoke 27, and the inner ring is fixed to the outer peripheral surfaces of both ends of the magnet 23. Has been. A clearance is opened between the outer surface of the rotor (hereinafter referred to as a magnet) 23 and the inner surface of the stator 21. Further, a clearance is also opened between both end surfaces of the magnet 23 and the bearing 29 and end surfaces of the inner step portions 11 b and 12 b of the frame members 11 and 13. A lead screw 31 is formed on the inner surface of the magnet 23 to travel in the optical axis direction. The cross-sectional shape of the lead screw 31 is V-shaped.

The lens L1 is disposed in the hollow portion of the magnet 23. A holder 33 is fixed to the outer edge of the lens L1. As easily shown in FIG. 2, the holder 33 is a ring-shaped member, and is formed with protrusions 34 extending in the radial direction of the lens from a plurality of locations on the outer periphery (three locations in this example). The protrusions 34 are arranged at a predetermined angle (120 ° in this example) around the optical axis OA (lens center line). A hole extending in the radial direction of the lens is formed in the outer surface of each protrusion 34. A screwing member 35 that is screwed into the lead screw 31 of the magnet 23 is accommodated in the hole. The screw member 35 includes a spring 36 housed in the hole of the protrusion 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 the spring 36 and screwed into the groove. In addition, a through hole 39 parallel to the optical axis direction is formed at the base of each protrusion 34.
The shape of the holder 33 is actually a shape twisted along the shape of one lead screw 31.

  As shown in FIG. 1A, three guide pins 41 are stretched between the end surfaces of the inner step portions 11b, 12b of the frame members 11, 12 of the fixed frame 10 facing each other. Both ends of each pin 41 are fitted in holes 11x and 12x formed in the end faces of the inner step portions 11b and 12b. Each guide pin 41 is parallel to the optical axis OA and is disposed at an equal central angle (120 °) with respect to the optical axis OA. Each guide pin 41 passes through the through hole 39 of the projection 34 of the lens holder 33, and the holder 33 moves in both directions in the optical axis direction on each guide pin 41. Thereby, the lens L1 moves bi-directionally in the optical axis direction.

A lens driving method of the lens driving device 1 will be described.
When the coil 25 of the stator 21 is energized and the stator 21 is excited, the magnet 23 rotates about the optical axis OA. When the magnet 23 rotates, the holder 33 screwed to the lead screw 31 of the magnet 23 via the screwing member 35 is sent along the lead screw 31 in the optical axis direction. At this time, since the holder 33 is prevented from rotating by the guide pin 41, it does not rotate. However, the ball 37 of the screwing member 35 rolls in the groove of the lead screw 31 or slides on one side wall of the groove in the optical axis direction. Pressed. 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 both directions along the optical axis.

  As described above, when the stepping motor 20 is driven, the magnet 23 that is a rotor is supported by the bearing 29 and is rotated. At this time, depending on the accuracy of the bearing 29, the deflection accuracy of the magnet, etc., the deflection of the lens 23 in the lens radial direction (radial direction) and backlash in the optical axis direction (thrust direction) occurs.

  In the lens driving device 1, as described above, since the gap between the guide pin 41 and the lens holder 33 is relatively small, the lens L1 moves on the optical axis without much vibration in the radial direction. it can. Further, the vibration in the radial direction is absorbed by the screwing member 35. That is, the backlash (vibration, eccentricity) of the magnet 23 that is the rotor is transmitted from the ball 37 of the screwing member 35 to the spring 36 and absorbed by the spring 36, and thus 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 in the thrust direction (optical axis direction) of the ball 37 always contacts both side walls of the groove. For this reason, the ball 37 cannot move in the thrust direction in the groove, and the play of the holder 33 in the thrust direction can be prevented. In this way, backlash and backlash are suppressed, and radial and thrust backlash, backlash, and hysteresis do not occur. For this reason, the zoom function and the focus function can be performed without degrading the optical performance such as image blur of the lens.

(Second embodiment)
3A and 3B are views for explaining a lens driving device according to a second embodiment of the present invention. FIG. 3A is a side sectional view and FIG. 3B 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 the method for supporting the magnet 23 of the stepping motor 20 is different. In FIG. 3, parts / members having the same configuration and operation as those of the lens driving device of FIG. 1 are denoted by the same reference numerals as those in FIG.

In the stepping motor 20 of this example, bearing pins 63 </ b> A and 63 </ b> B are erected from both end surfaces of the magnet 23. Each bearing pin 63 is arranged in parallel with the optical axis direction and distributed around the optical axis OA. The fixed lens side bearing pin 63 </ b> A is erected from the magnet 23 via a thrust damper 65. The thrust damper 65 biases the bearing pin 63 in the thrust direction (optical axis direction). For example, a spring (coil, plate), rubber (cushion material), or the like can be used.
There are a plurality of bearing pins 63.

  An annular groove 67 for fitting the bearing pin 63 is formed on the end surfaces of the step portions 11b and 12b of the fixed frame members 11 and 12, respectively. The width of each groove 67 is a dimension obtained by adding a predetermined clearance to the diameter of the bearing pin 63. When the bearing pins 63 of the magnet 23 are fitted into the grooves 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 of FIG. When the magnet 23 rotates around the optical axis OA when the stepping motor is in operation, each bearing pin 63 moves while sliding in the groove 67 of each fixed frame member 11, 12.

  In this example, the magnet 23 is supported by a simple mechanism such as a pin 63 and a groove 67. In such a method, compared to the support method using the bearing of FIG. 1, the magnet 23 is likely to be loose or shaken, but the radial shake is eliminated by moving the holder 33 along the guide pin 41. The vibration and eccentricity in the radial direction are absorbed by the screwing member 35. Further, the backlash in the thrust direction is suppressed by urging the ball 37 of the screwing member 35 to the groove of the lead screw 31 of the rotor 23 by the spring 36. Further, the play in the thrust direction is absorbed by the thrust damper 65. In this example, a bearing is not used to support the magnet 23, and the structure of the rotation support mechanism of the magnet 23 is simplified, so that the cost can be reduced.

  The annular groove 67 may be a step instead of a groove. For example, if three or more pins 63 are used so that the inner side or the outer side of these pins are guided by the circumferential surface by a step, the function of the bearing of the magnet 23 is achieved.

(Third embodiment)
4A and 4B are views for explaining a lens driving device according to a third embodiment of the present invention. FIG. 4A is a side sectional view and FIG. 4B is a front view.
The lens driving device 71 of this example also has substantially the same configuration as the lens driving device of FIG. 1, but the method for supporting the magnet 23 of the stepping motor 20 is different. Also in FIG. 3, parts / members having the same configuration and operation as the lens driving device in FIG. 1 are denoted by the same reference numerals as those in FIG.

The magnet 23 of the stepping motor 20 in this example is supported by the bearing pin 63 on the fixed lens side as in the lens driving device of FIG. 2, and is supported by the ball 73 on the opening side.
A bearing pin 63 is erected via a thrust damper 65 on the end surface of the magnet 23 on the fixed lens side. Each bearing pin 63 is distributed around the optical axis OA. An annular groove 67 into which the bearing pin is fitted is formed on the end surface of the step portion 11b of the frame member 11 on the fixed lens side. When the bearing pins 63 of the magnet 23 are fitted into the grooves 67, the end of the magnet 23 on the fixed lens side is rotatably supported by the fixed frame 10.

  On the other hand, an annular groove 23a 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. Then, on the side wall 12c of the fixed frame member 12 on the opening side, a flange portion 12d protruding inward is formed. 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 23 a of the magnet 23 and the annular groove 12 e of the collar portion 12 d of the frame member 12. Thus, 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.

  Also in this example, the magnet 23 is supported by a simpler method compared to the lens driving device of FIG. 1, and the cost can be reduced. Further, in the support method using the bearing pin 61 and the groove 67, friction between the outer surface of the pin 63 and the side surface or 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 via the ball 73 having a small coefficient of friction, friction hardly occurs and the load on the motor 20 can be reduced.

(Fourth embodiment)
5A and 5B are views for explaining a lens driving device according to a fourth embodiment of the present invention. FIG. 5A is a side sectional view, and FIG. 5B is a part of FIG. An enlarged view, FIG. 5C, is a front view.
The lens driving device 201 of this example also has substantially the same configuration as the lens driving device of FIG. 1, but the structure and supporting method of the rotor of the stepping motor is different from the structure and supporting method of the lens holder. Parts / members having the same configuration / action as those of the lens driving device of FIG. 1 are denoted by the same reference numerals as those of FIG. Note that the lens driving device of this example includes only the moving lens L1.

First, the structure of the rotor of the stepping motor and the support method will be described.
The rotor 80 of the stepping motor 20 in this example has a cylindrical holder magnet (sleeve) in which a cylindrical rotor magnet 81 is manufactured by molding or cutting a resin material (for example, sliding grade POM-MSO2). 83 is attached. The sleeve 83 has a cylindrical shape concentric with the stator 21, and a rotor magnet 81 is fixed to the outer peripheral surface by bonding, outsert molding, or the like. A lead screw 85 is formed on the inner peripheral surface of the sleeve 83 so as to proceed in the optical axis direction. The cross-sectional shape of the lead screw 85 is substantially U-shaped. The sleeve 83 has a split structure so that the rotor magnet 81 can be incorporated.

  The sleeve 83 is supported by the magnetic bearings 101 and 103 so as to be rotatable with respect to the fixed frame 10. The two magnetic bearings 101 support the both ends of the rotor 80 in a non-contact manner with respect to the fixed frame 10 in the thrust direction. Further, the two magnetic bearings 103 support the 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 view 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 adhesion 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 adhesion or the like. The opposing surfaces of the permanent magnets 101R and 101S are magnetized so as to have the same polarity (N pole in this example). Permanent magnets 101R and 101S may be ring-shaped or may be bonded in the form of divided chips along the circumferential surface. Chips 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 embedded along the outer periphery of the end portion of the sleeve 83 and fixed by adhesion or the like. The large-diameter permanent magnet 103S is embedded in the inner surface of the step portion 11b of the frame member 11 facing the small-diameter permanent magnet 103R, and is fixed by adhesion or the like. The 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 in a ring shape or may be attached in a divided chip shape 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 repulsive force of the facing surface of each permanent magnet 101. Also in the radial direction, the rotor 80 is held in non-contact with the fixed frame 10 by the magnetic repulsive force 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, there is no bearing hysteresis and the motor output can be utilized to the maximum. Further, since no sliding noise of the bearing is generated, noise can be reduced.

  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, distance between magnets, etc. of each permanent magnet match the specifications of the stepping motor (rotation speed, rotation speed, etc.), the dimensions and weight of the motor, and the load (weight of the lens and lens holder). Adjust.

Next, the structure and supporting method of the lens holder 90 will be described.
Also in this example, the lens holder 90 moves bi-directionally in the optical axis direction on the guide pin 41 that is parallel to the optical axis OA and disposed at the same central angle (120 °) with respect to the optical axis OA. However, the two guide pins 41 pass through a groove 91 extending in the radial direction from 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, component manufacturing errors and assembly errors can be missed.

  A screwing 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 in the outer surface of the screwing portion 95. In this hole, a screwing member (pin) 97 to be screwed into the lead screw 85 of the sleeve 83 is accommodated. The screw member 97 is screwed with a clearance that allows the lead screw 85 of the sleeve 83 and the rotor 80 to swing. With such a structure, the lens holder 90 supported by the through hole 93 can move without being influenced by the shake of the rotor 80 or the like.

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 of FIG. 5, when the rotor 80 (lens L1 and 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. I need it. 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 the permanent magnets of the bearings 101 ′ and 103 ′. By providing such back yokes 102 and 104, a high magnetic repulsive force can be obtained by concentrating lines of magnetic force.

1A and 1B are diagrams illustrating a lens driving device according to a first embodiment of the present invention, in which FIG. 1A is a side cross-sectional view and FIG. 1B is a front view. It is a figure which shows the inside of the lens drive device of FIG. It is a figure explaining the lens drive device which concerns on the 2nd Embodiment of this invention, FIG. 3 (A) is side sectional drawing, FIG.3 (B) is a front view. It is a figure explaining the lens drive device which concerns on the 3rd Embodiment of this invention, FIG. 4 (A) is side sectional drawing, FIG.4 (B) is a front view. FIGS. 5A and 5B are diagrams illustrating a lens driving device according to a fourth embodiment of the present invention, FIG. 5A is a side cross-sectional view, and FIG. 5B is an enlarged view of a part of FIG. FIG. 5C is a front view. 6A and 6B are diagrams showing a modification of the lens driving device of FIG. 5, in which FIG. 6A is a side cross-sectional view, and FIG. 6B is a partially enlarged view of FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Lens drive device 10 Fixed frame 11, 12 Frame member 11a, 12a Flange part 11b, 12b Side wall 11c, 12c Inner step part 11x, 12x Hole 12d Collar part 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 Coil 27 Yoke 29A, 29B Bearing 31 Lead screw 33 Holder 34 Projection 35 Screw member 36 Spring 37 Ball 39 Through hole 41 Guide pin 61 Lens driving device 63A, 63B Bearing pin 65 Thrust Damper 67 Groove 71 Lens drive device 73 Ball 80 Rotor 81 Rotor magnet 83 Sleeve 85 Groove 90 Lens holder 91 Groove 93 Through hole 95 Screw portion 97 Screw member 101 Thrust bearing 103 Radial bearing 102, 104 Back yoke 201 Lens drive device L1, L2 Lens OA Optical axis

Claims (10)

An air-core stepping motor having a cylindrical stator including a coil, and a cylindrical rotor including a magnet rotatably accommodated in the stator;
A lens provided so as to be 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 so that the lens can move in the axial direction and to prevent the lens from rotating.
A lead screw is formed on the inner surface of the rotor magnet or the hollow member attached thereto,
A lens driving device characterized in that a screwing member that is screwed with the lead screw and is urged flexibly toward the groove of the screw is provided at an outer edge of the lens. An air-core stepping motor having a cylindrical stator including a coil, and a cylindrical rotor including a magnet rotatably accommodated in the stator;
A lens provided so as to be 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 so that the lens can move in the axial direction and to prevent the lens from rotating.
A lead screw is formed on the inner surface of the rotor magnet or the hollow member attached thereto,
A lens driving device characterized in that a screwing member screwed with the lead screw is provided on an outer edge of the lens.   The lens driving device according to claim 1, wherein the lead screw is directly formed on an inner periphery of the magnet of the rotor.   The lens driving device according to claim 1, wherein the screwing member includes a ball applied to the screw groove and an elastic member that urges the ball toward the screw groove. A pin extending in the axial direction is erected on the rotor,
5. The lens driving device according to claim 1, wherein the stator or a member to which the stator is fixed is formed with an annular groove in which the pin is fitted and slidable.   6. The lens driving device according to claim 5, wherein a thrust damper is attached to the base of the pin.   The lens driving 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.   The magnetic bearing is formed of a pair of a permanent magnet attached to the outer periphery and / 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. The lens driving device according to claim 7, wherein the lens driving device is provided.   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. An air-core stepping motor having a cylindrical stator including a coil, and a cylindrical rotor including a magnet rotatably accommodated in the stator;
A lens provided so as to be movable 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.

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