JP2008043010A - Air core motor and lens drive unit - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an air core motor which can be reduced in weight and cost by improving a rotation supporting method of a rotor, and to provide a lens drive unit using the air core motor. <P>SOLUTION: The air core motor 1 comprises: a cylindrical stator 2 which includes a coil 22 and a yoke 21; the cylindrical rotor 3 which includes a magnet 32 rotatably accommodated in the stator; and a rotation supporting means 4 which rotatively supports the rotor 3 with respect to the stator 2. The rotation supporting means 4 is fixed to a bracket 5 which is externally fit to the stator 2, and comprises a plurality of shafts 41 which are distributively arranged on a circumference, and a plurality of rollers 42 which are rotatably fit to each of the shafts 41. The plurality of rollers 42 rotatively support the rotor 3 by contacting with the external periphery of the rotor 3 so as to be rollable. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to an air-core motor and an apparatus for driving a lens using the motor. In particular, the present invention relates to an air-core motor or the like having improved rotation support means for rotating and supporting a rotor with respect to a stator.

  As an apparatus for driving a lens by using an air-core motor, the present inventors have proposed an apparatus in which the lens is improved so that the lens can be moved without backlash, vibration, and hysteresis (see Patent Document 1).

FIG. 9 is a diagram illustrating a lens driving device proposed in Patent Document 1. In FIG.
The lens driving device 201 mainly includes a cylindrical fixed frame 210 that is divided into two in the optical axis direction, an air-core stepping motor 220 fixed in the same frame, and a holder 230 that supports the lens L1. . The fixed frame 210 is provided with guide pins 211 extending on the optical axis. The holder 230 is inserted in the guide pin 211, is prevented from rotating on the optical axis, and moves in both directions. The motor 220 includes a cylindrical stator 221 and a cylindrical rotor 222 that is rotatably accommodated in the stator 221. The rotor 222 is fitted on the concentric cylinder in the stator 221 and is rotatably supported by the fixed frame 210 by a bearing 240. In addition, a lead screw 222 a that travels in the optical axis direction is formed on the inner surface of the rotor 222.

  The holder 230 is formed with a protrusion extending in the radial direction of the lens L1, and a screwing member 231 is accommodated on the end surface of the protrusion. The screw member 231 includes a spring 232 accommodated in the protrusion and a ball 233 disposed at the tip of the spring 232, and the ball 233 is screwed to a lead screw 222 a formed on the inner surface of the rotor 222. When the motor 220 is driven and the rotor 222 rotates, the holder 230 screwed with the lead screw 222a is sent along the screw in the optical axis direction. Since the vibration of the holder 230 is absorbed by the screwing member 231, the lens can be moved without backlash or backlash.

Japanese Patent Application No. 2003-422896

  As described above, the lens driving device can move the lens without backlash or backlash, so that the lens can be positioned with high accuracy. As one of means for realizing a reduction in cost and weight of the lens driving device, the present inventors paid attention to a rotor rotation support method. SUMMARY OF THE INVENTION An object of the present invention is to provide an air core motor capable of realizing a reduction in weight and cost by improving a method for supporting rotation of a rotor, and a lens driving device using the air core motor. It is another object of the present invention to provide an air core motor capable of realizing a smooth operation even when the dimensional accuracy of parts is somewhat inferior, and a lens driving device using the air core motor.

  An air-core motor of the present invention includes a cylindrical stator including a coil and a yoke, a cylindrical rotor including a magnet rotatably accommodated in the stator, and a rotation that rotatably supports the rotor with respect to the stator. An air-core motor comprising: a support means, wherein the rotation support means is fixed to the stator, and a plurality of shafts are arranged in a distributed manner on the circumference, and a plurality of the shafts are rotatably fitted to each of the shafts. A plurality of rollers, wherein the plurality of rollers are in rolling contact with the outer periphery of the rotor to rotatably support the rotor.

  According to the present invention, a roller that is rotatably fitted to the shaft is used as a means for rotating and supporting the rotor, and low friction characteristics equivalent to those of commercially available bearings (ball bearings, roller bearings) are obtained. The rotor rotation support means of the present invention is cheaper and lighter than commercially available bearings. On the other hand, the frictional force is small as compared with the sliding bearing. Further, assembling is easier than in the case of using a simple roller (no shaft). This is advantageous for reducing the weight and price of the motor.

  In the present invention, one end portion of the shaft is press-fitted or bonded to the stator or a member fixed thereto, and the other end portion of the shaft extends in a radial direction formed on a ring-shaped shaft pressing plate. It is preferable to be accommodated in the long hole.

  In this case, the shaft has (can be) elastic in the radial direction. Therefore, even when the dimensional accuracy of the rotor is slightly poor (when the sliding surface of the sliding ring is not smooth or the roundness of the sliding ring is somewhat poor), the shaft is deformed so that it is in the radial direction. Since the vibration is absorbed, the rotor can be rotated smoothly.

  Furthermore, since the shaft is in the radial direction, the rotor is pressed from the periphery toward the optical axis by the roller, so that the rotor can be biased and supported toward the optical axis.

  In the present invention, an external gear attached to the rotor, an idler gear rotatably supported with respect to the stator and meshing with the external gear, and an outer ring formed with internal teeth meshing with the idler gear And can be provided.

  In this case, an outer ring that rotates in a direction opposite to the rotor at a certain rotation ratio can be provided. Such an outer ring is decelerated and can be applied to increase torque and resolution. That is, the torque can be increased by the reduction ratio, and the number of steps can be increased. Also in this case, the outer ring can be rotatably supported by a method that is relatively inexpensive and can be reduced in weight.

  The lens driving device of the present invention includes an air core motor having a cylindrical stator including a coil and a cylindrical rotor including a magnet rotatably accommodated in the stator, and a shaft in the air core motor. A lens driving device including: a lens provided so as to be movable in a direction, 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 an axial direction and is prevented from rotating. A guide member is provided, a lead screw is formed on the inner surface of the rotor magnet or a hollow member attached thereto, and a screwing member for screwing the lead screw is provided on the outer edge of the lens, The air-core motor includes rotation support means for rotating and supporting the rotor with respect to the stator, and the rotation support means with respect to the stator A plurality of rollers arranged in a distributed manner on the circumference, and a plurality of rollers rotatably fitted on each of the shafts, wherein the plurality of rollers are in rolling contact with the outer circumference of the rotor. Each rotor is rotatably supported.

  According to the present invention, since the rotation support means of the rotor can absorb the radial shake of the rotor and the play in the optical axis direction, image blurring can be reliably prevented. Further, as a means for rotating and supporting the rotor, a low friction characteristic equivalent to that of a commercially available bearing (ball bearing, roller bearing) is obtained by using a roller that is rotatably fitted to the shaft. This rotor rotation support means is cheaper and lighter than commercially available bearings. On the other hand, the frictional force is smaller than that of a plain bearing, and the assembly is easier than when a simple roller (without a shaft) is used. This is advantageous for reducing the weight and price of the motor.

  As apparent from the above description, according to the present invention, it is possible to provide an air-core motor that can be manufactured at low cost and can be reduced in weight. Furthermore, it is possible to provide a lens driving device that uses this air-core motor to move the lens without causing backlash, vibration, or hysteresis.

BEST MODE FOR CARRYING OUT THE INVENTION

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
FIG. 1 is a side sectional view for explaining the structure of an air-core motor according to a first embodiment of the present invention.
FIG. 2 is an exploded perspective view of the air-core motor of FIG.
The air-core motor 1 includes a cylindrical stator 2 including a coil and a yoke, a cylindrical rotor 3 including a magnet rotatably accommodated in the stator 2, and the rotor 3 rotatably supported with respect to the stator 2. A rotation support means 4 and a sleeve-like bracket 5 in which the rotation support means 4 is accommodated.

  The stator 2 has two stator pieces 21 arranged in the optical axis direction. Each stator piece 21 is formed by combining two pairs of claw pole type yokes so that pole teeth mesh with each other and integrally fixing them with a coil bobbin. Each coil bobbin is formed with a concave portion having a U-shaped cross section, and a coil 22 is wound around and accommodated in each concave portion. On the outer surface of the stator 2, terminal pins for supplying power to the coils 22 are erected.

  The rotor 3 has a cylindrical magnet holder (made of resin) 31, and two cylindrical magnets 32 are attached to the outer surface of the holder 31 side by side in the optical axis direction. In addition, cylindrical sliding rings (made of metal) 33 are attached to both ends of the holder 31. The rotor 3 is fitted into the stator 2 on a concentric cylinder. At this time, as shown in FIG. 1, each magnet 32 faces each stator piece 21 of the stator 2, and the sliding rings 33 at both ends protrude from both ends of the stator 2. A roller 42 of the rotation support means 4 described later is in rolling contact with the outer surface (sliding surface) of each sliding ring 32.

The bracket 5 is a sleeve-like one that is fitted on the stator 2, and includes a pair of bracket pieces 5A and 5B that are divided into two in the optical axis direction. On the end face of each bracket piece 5, a recess 5a for accommodating the rotation support means 4 is formed. The depth of the concave portion 5a is substantially the same as the thickness of a roller 42 of the rotation support means 4 described later. The recesses 5a are formed at equal intervals in the circumferential direction (in this example, the center angle is 60 °). A ring-shaped presser plate 6 is attached to the end face of each bracket piece 5. The presser plate 6 is for supporting the rotation support means 4 accommodated in the recess 5 a of the bracket piece 5. A positioning pin 5b is erected on the end face of each bracket piece 5, and a positioning hole 6a corresponding to the positioning pin 5b is formed in the presser plate 6. The presser plate 6 is positioned on the end face of the bracket piece 5 and fixed by adhesion or welding.
Further, on the inner peripheral surface of each bracket piece 5, a step portion 5 c that projects inward is formed.

  The bracket pieces 5A and 5B are applied so as to sandwich the rotor 3 and the stator 2 assembly assembled as described above from both sides in the optical axis direction. At this time, the stator 2 is fixed in contact with the step portion 5 c of each bracket piece 5. The rotor 3 is rotatably supported by the bracket 5 by a plurality (six in this example) of rotation support members 4 at the sliding ring 32 at both ends.

3A and 3B are diagrams for explaining the rotation support member. FIG. 3A is a side sectional view of the roller, FIG. 3B is a front view of the roller, and FIG. 3C is a side view of the shaft.
4A and 4B are diagrams for explaining a mounting state of the rotation support member. FIG. 4A is a side sectional view, and FIG. 4B is a front view.
The rotation support member 4 includes a shaft 41 (see FIG. 3C) (for example, metal) and a roller 42 (see FIGS. 3A and 3B) that is rotatably fitted to the coaxial 41 (for example, made of resin). ). A through hole 42 a through which the shaft 41 is inserted is formed in the shaft core of the roller 42. The roller 42 rotates around this shaft 41. At the center of the side surface of the roller 42, a small-diameter step portion 42b for receiving a thrust is provided.

  Each rotation support member 4 is accommodated in a recess 5 a formed on the end face of each bracket piece 5. As shown in FIG. 4, one end of the shaft 41 is press-fitted and fixed in a hole 5d (see also FIG. 2) formed in the bottom of the bracket recess 5a, and the other end is a long hole formed in the presser plate 6. 6b is inserted. This long hole 6b is a long hole in the radial direction. The elongated hole 6b in FIG. 4 is exaggerated. As shown in FIG. 2, the rollers 42 inserted through the respective shafts 41 are in rolling contact with the sliding surfaces (outer surfaces) of the respective sliding rings 33 of the rotor 3. The diameter of the shaft 41 is selected according to the balance between elasticity and strength.

  When the coil 21 of the motor 1 is energized and the stator 21 is excited, the rotor 3 rotates. At this time, the rollers 42 of the respective rotation support members 4 contact the sliding surfaces of the respective sliding rings 33 of the rotor 3. The rotor 3 is rotationally supported with respect to the bracket 5 by rolling contact. At this time, since one end of the shaft 41 is inserted into the long hole 6a of the presser plate 6, the shaft 41 has (is) a certain degree of elasticity in the radial direction. For this reason, even if the sliding surface of the sliding ring 33 of the rotor 3 is somewhat smooth or the roundness of the sliding ring 3 is somewhat bad, as shown by the imaginary line in FIG. Since the vibration is absorbed by the deformation so as to be, the rotor 3 can be smoothly rotated. Moreover, since it can produce with the metal axis | shaft 41 and the resin-made rollers 42, it is cheaper than the case where a commercially available bearing (a ball bearing or a roller bearing) is used, and the low friction characteristic equivalent to a bearing is realizable. On the other hand, the frictional force is small compared to a plain bearing, and assembly is easier than a simple roller (no shaft).

  When the motor 1 is manufactured, it is general that the rotor-stator assembly is assembled after the rotation support member 4 is fixed between the bracket piece 5 and the holding plate 6. Here, when the rotation support member 4 is fixed between the bracket piece 51 and the presser plate 6, the rotation support member 4 may be incorporated so that the shaft 41 of the presser plate 6 is located on the innermost side of the long hole 6 b. preferable. Then, when the rotor 3 is assembled later, the shaft 41 is pushed by the sliding surface of the rotor 3 and moves outward halfway through the long hole 6b. In other words, the sliding surface of the rotor 3 is biased and supported by each roller 42 toward the optical axis. For this reason, the rotor 3 can be fixed so that there is no play with respect to the optical axis. The clearance of the long hole 6b (the distance d between the shaft 41 and the outer end of the long hole 6b when the rotor 3 is incorporated) is 20% or less of the air gap between the magnet 32 of the rotor 3 and the stator 2. It is preferable that

  In this example, six rotation support members 4 are provided. However, in consideration of dispersion and balance of power points, it is preferable that the number of rotation support members 4 is an odd number by vector calculation, and it is more preferable that more portions are provided. However, considering axial loss and the like, 5 to 7 are preferable.

FIG. 5 is a side sectional view for explaining the structure of the air-core motor according to the second embodiment of the present invention.
FIG. 6 is an exploded perspective view of the air-core motor of FIG.
FIG. 7 is a front sectional view of the air-core motor of FIG.
The air-core motor 11 of this example has a structure substantially similar to that of the air-core motor 1 of FIG. 1 except that an outer ring 7 that rotates in a reverse direction with a certain rotation ratio with respect to the rotor 3 ′ is provided. is there. 5, 6, and 7, parts having the same configuration and action as the air-core motor 1 in FIG. 1 are denoted by the same reference numerals as those in FIG.

  As shown in FIGS. 5 and 6, the outer ring 7 includes a bracket ring 71, a sliding ring 72, and an internal gear 73 fixed side by side in the optical axis direction. On the other hand, an external gear 34 is provided at the tip (right side of the figure) of the sliding ring 33 on one side (right side of the figure) of the rotor 3. When the external gear 34 meshes with the internal gear 73 of the outer ring 7 via a plurality (three in this example) of idler gears 8, the outer ring 7 rotates in the opposite direction to the rotor 3 '(details will be described later). .

  The outer ring 7 is supported rotatably with respect to the bracket 5. As shown in FIG. 5, a flange portion 71 a projecting inward is formed at the end portion of the bracket ring 71 of the outer ring 7. The outer ring 7 is rotatably supported by the bracket 5 by the rotation support member 4-2 with the flange portion 71a and the sliding ring 72. This rotation support member 4-2 is the same as the rotation support member 4 of FIG.

  The air-core motor 11 further includes an adjustment member 10 that adjusts the backlash of the idler gear 8 (see FIG. 7). The backlash adjusting member 10 is obtained by arranging two rotation support members 4 in FIG. 1 in the radial direction.

  The outer diameter of the bracket piece 5B ′ on the side where the external gear 34 is provided (the right side in the figure) is larger than the outer diameter of the other bracket piece 5A, and the width of the end surface is wide. On one end (right side in the drawing) of the bracket piece 5B ', a recess 5a for accommodating the rotation support members 4-1 and 4-2 for the rotor and the outer ring, the idler gear 8 and the backlash adjustment member are accommodated. A recess 5f in which 10 is accommodated is formed. As shown in FIG. 7, the rotation support member accommodating recesses 5a are formed at equal intervals in the circumferential direction (in this example, the central angle is 120 °). The idler gear accommodating recesses 5f are also formed at equal intervals in the circumferential direction (in this example, the center angle is 120 °). Both the concave portions 5a and 5f are arranged with a uniform interval in the circumferential direction (in this example, the central angle is 60 °). The holding plate 9 is fixed to this end face.

  The rotation support member housing recess 5a includes a rotor rotation support member 4-1 and an outer ring rotation support member 4-2, the rotor rotation support member 4-1 on the inner side, and the outer ring rotation support member 4-2. Arranged and accommodated outside. A gap is slightly opened in the radial direction between the two rotation support members. The support method of each rotation support member 4 is the same as that of the above-mentioned example. Further, the presser plate 9 is formed with a step 9a for positioning these rotation support members at the bottom of the recess 5a (see FIGS. 5 and 6).

An idler gear 8 and a backlash adjusting member 10 are accommodated in the idler gear accommodating recess 5f. As shown in FIG. 7, the idler gear 8 is disposed in the center of the recess 5f, and the backlash adjusting members 10 are disposed on both sides thereof. The two rotation support members 4 constituting the backlash adjusting member 10 are arranged with a slight clearance in the radial direction. The support method of each rotation support member 4 is the same as that of the above-mentioned example.
The idler gear 8 and the backlash adjusting member 10 are disposed apart from each other in the optical axis direction. For this reason, as shown in FIG. 6, a step portion 5g for floating and holding the idler gear 8 from the bottom portion is formed at the bottom portion of the concave portion 5f. Further, a step portion 9 a is formed on the presser plate 9 to position each rotation support member 4 constituting the backlash adjusting member 10 at the bottom of the recess 5 f.

  On the end surface of the bracket piece 5B 'on the opposite end side (left side in the figure), as shown in FIG. 6, the recess 5h in which the outer ring rotation support member 4-2 is accommodated is evenly spaced in the circumferential direction (this example In this case, it is formed by opening 60 °. The presser plate 6 is also fixed to this end face as in the above example.

  In addition, the rotation support member 4-1 for rotors is accommodated in the end surface of the other bracket piece 5A similarly to FIG.

In the air-core motor 11 of this example, when the coil 22 of the motor 11 is energized and the stator 21 is excited, the rotor 3 rotates. At this time, each rotation support member 4-1 The rotor 3 is rotationally supported with respect to the bracket 5 by rolling contact with the sliding surface of the sliding ring 33. When the rotor 3 rotates, each idler gear 8 that meshes with the external gear 34 of the rotor 3 rotates. And the outer ring | wheel 7 which has the internal gear 73 meshed | engaged with each idler gear 8 rotates in the direction opposite to the rotation direction of the rotor 3. As shown in FIG. At this time, each rotation support member 4-2 is in rolling contact with the sliding surface (inner surface) of the sliding ring 72 of the outer ring 7 and the inner surface of the flange portion 71 a of the bracket ring 71 to rotatably support the outer ring 7. . In each backlash adjusting member 10 on both sides of the idler gear 8, a pressure is applied to the rotor 3 inward by the inner rotation support member 4, and an outer direction is applied to the outer ring 7 by the outer rotation support member 4. Since the pressure is applied to each of the idler gears 8, the backlash of each idler gear 8 can be made constant. These rotation support members 4 also have a function of rotating and supporting the rotor 3 and the outer ring 7.
The reduction ratio between the outer ring 7 and the rotor 3 is determined by the ratio of the number of teeth of the internal gear 73 of the outer ring 7 and the external gear 34 of the rotor 3.

  The air-core motor 11 of this example can be used when torque is insufficient or when higher resolution (up the number of steps) is required.

FIG. 8 is a diagram illustrating a lens driving device according to an embodiment of the present invention.
The lens driving device 101 mainly includes an air-core motor 1 and a holder 130 that supports the lens L1. A guide pin 111 extending on the optical axis is provided between the presser plates 6 of the air-core motor 1. The holder 130 is inserted through the guide pin 111 and is rotated around the optical axis OA to move in both directions. The air core motor 1 has substantially the same structure as the motor 1 of FIG. 1, and the rotor 3 is rotatably supported by the bracket 5 and the presser plate 6 by the rotation support member 4. However, on the inner surface of the magnet holder 31 of the motor 1, a lead screw 31a that proceeds in the optical axis direction is formed.

  The lens holder 130 is formed with a protrusion extending in the radial direction of the lens L1, and a screwing member 131 is accommodated on the end surface of the protrusion. The screw member 131 includes a spring 132 housed in the protrusion and a ball 133 disposed at the tip of the spring 132, and the ball 133 is screwed to a lead screw 31 a formed on the inner surface of the magnet holder 31. When the motor 1 is driven and the rotor 3 rotates, the holder 130 screwed with the lead screw 31a is sent along the screw 31a in the optical axis direction.

It is side surface sectional drawing explaining the structure of the air-core motor which concerns on the 1st Embodiment of this invention. It is a disassembled perspective view of the air-core motor of FIG. FIG. 3A is a side sectional view of the roller, FIG. 3B is a front view of the roller, and FIG. 3C is a side view of the shaft. It is a figure explaining the attachment state of a rotation support member, FIG. 4 (A) is side sectional drawing, FIG.4 (B) is a front view. It is side surface sectional drawing explaining the structure of the air-core motor which concerns on the 2nd Embodiment of this invention. It is a disassembled perspective view of the air-core motor of FIG. It is front sectional drawing of the air-core motor of FIG. It is a figure explaining the lens drive device concerning an embodiment of the invention. It is a figure explaining the lens drive device proposed by patent document 1. FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Air core motor 2 Stator 21 Stator piece 22 Coil 3 Rotor 31 Magnet holder 32 Magnet 33 Sliding ring 4 Rotation support member 41 Shaft 43 Roller 5 Bracket 6 Presser plate 7 Outer ring 71 Bracket ring 72 Sliding ring 73 Internal gear 8 Idler gear 9 Presser plate 101 Lens driving device 111 Guide pin 131 Screwing member 132 Spring 133 Ball

Claims (4)

A cylindrical stator including a coil and a yoke;
A cylindrical rotor including a magnet rotatably housed in the stator;
Rotation support means for rotatingly supporting the rotor with respect to the stator;
An air-core motor comprising:
The rotation support means comprises:
A shaft fixed to the stator, and a plurality of shafts distributed on the circumference;
A plurality of rollers rotatably fitted to each of the shafts;
Have
The air-core motor, wherein the plurality of rollers are in rolling contact with the outer periphery of the rotor to rotatably support the rotor. One end of the shaft is
It is press-fitted or bonded to the stator or a member fixed thereto,
2. The air-core motor according to claim 1, wherein the other end portion of the shaft is accommodated in a long hole extending in the radial direction formed in a ring-shaped shaft pressing plate. further,
An external gear attached to the rotor;
An idler gear that is rotatably supported with respect to the stator and meshes with the external gear;
An outer ring formed with inner teeth meshing with the idler gear;
The air-core motor according to claim 1, further comprising: An air-core motor having a cylindrical stator including a coil, and a cylindrical rotor including a magnet rotatably accommodated in the stator;
A lens that is axially movable in the air-core motor;
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 magnet of the rotor or a hollow member attached thereto,
A screwing member for screwing the lead screw is provided on the outer edge of the lens,
The air core motor is
Rotation support means for rotatingly supporting the rotor with respect to the stator;
The rotation support means comprises:
A shaft fixed to the stator, and a plurality of shafts distributed on the circumference;
A plurality of rollers rotatably fitted to each of the shafts;
Have
The lens driving device, wherein the plurality of rollers are in rolling contact with the outer periphery of the rotor to rotatably support each rotor.

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