JP2006087174A - Stepping motor and electronic apparatus using stepping motor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a stepping motor which can raise output torque and transmit power to a motive power transmitting part with accuracy. <P>SOLUTION: This stepping motor is equipped with a rotor which has a magnetized rotor magnet and the motive power transmitting part and a stator which is composed of a coil for generating a magnetic field by supplied electric energy and a yoke constituting a magnetic path for a magnetic field. The rotor magnet transmits power to the motive power transmitting part via a connecting hole, and for the connecting hole, the form at a plane vertical to the axis of rotation has such turn stopping form that the distance from the axis of rotation is not fixed. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a stepping motor and an electronic device using the stepping motor.

  A stepping motor for an electronic timepiece has a structure in which coils, a stator, and a rotor, which are important components, are dispersed in a plane. This is a very good structure for a watch that is required to be small and thin, and has an effect that it can be manufactured at low cost.

   FIG. 9 is a configuration diagram of a stepping motor conventionally used in an electronic timepiece. 9, the stepping motor includes a stator 301 having a rotor accommodating through hole 303, a rotor 302 rotatably accommodated in the rotor accommodating through hole 303, and magnetized to two poles (S pole and N pole), screws 312, A magnetic core 308 integrated with the stator 301 by 313 and a coil 309 wound around the magnetic core 308 are provided.

  The stator 301 formed of a magnetic material is provided with two notches (outer notches) 306 and 307 at positions facing each other with the rotor housing through hole 303 interposed therebetween. The outer notches 306 and 307 and the rotor Saturable portions 310 and 311 are formed between the accommodation through holes 303. The stator 301 is provided with two positioning notches (inner notches) 304 and 305 that are continuous with the rotor accommodating through-hole 303 and are opposed to each other with the rotor accommodating through-hole 303 interposed therebetween. . In a state where the coil 309 is not excited, the rotor 302 is stably stopped at a position where the magnetic pole axis A is orthogonal to the line segment connecting the inner notches 304 and 305.

  If a rectangular wave pulse signal is supplied to the coil 309 and a current i is supplied in the direction of the arrow, a magnetic flux is generated in the stator 301 in the direction of the arrow C. As a result, the saturable portions 310 and 311 are saturated to increase the magnetic resistance, and then the rotor 302 rotates 180 degrees in the direction of arrow B due to the interaction between the magnetic pole generated in the stator 301 and the magnetic pole of the rotor 302. Stop stably.

  Next, when a pulse signal of a rectangular wave having a reverse polarity is supplied to the coil 309 and a current is passed in the opposite arrow direction, a magnetic flux is generated in the stator 301 in the opposite arrow C direction. As a result, the saturable portions 310 and 311 are first saturated, and then the rotor 302 rotates 180 degrees in the direction of arrow B and stably stops due to the interaction between the magnetic pole generated in the stator 301 and the magnetic pole of the rotor 302. . Thereafter, by supplying signals having different polarities (alternating signals) to the coil 309 in this way, the above operation is repeated, and the rotor 302 can be continuously rotated in the direction of arrow B by 180 degrees. it can.

  The rotor 302 has a gear and a shaft integrally formed with a rotor true and a magnet fixed to each other, and transmits rotational power by the gear. The rotor true may be integrated with a metal member and a magnet by press-fitting or the like, but in order to reduce the cost, the magnet is often insert-molded to form the rotor true with plastic.

  10A and 10B show a rotor structure in which a magnet is insert-molded with plastic. FIG. 10A is a side view, and FIG. 10B is a bottom view. The rotor 302 includes an anisotropic rotor magnet 302a having a polarity of two poles, a holding portion for holding the magnet 302a, a kana, and a rotor stem 302b in which shafts at both ends are integrally molded. The rotor magnet 302a is fixed to the rotor stem 302b by insert molding.

The rotor magnet is fixed to the plastic by its outer peripheral side and upper and lower surfaces. As for the outer peripheral side surface, a part of the rotor true has a belt shape, and the rotor magnet and the rotor true are fixed at four places. Thereby, the step motion of the rotor magnet can be transmitted to the rotor true, and the rotor true can be rotated.
JP-A-10-68784 (FIG. 9)

  By the way, a stepping motor for an electronic timepiece may be more advantageous than a general cylindrical stepping motor in terms of the aspect that can be reduced in thickness and the degree of freedom in design, depending on the application. For example, there is a great need for miniaturization and thinning of driving devices for optical parts such as lenses used in cameras, and there is a strong demand for miniaturization and thinning of lens driving devices mounted on portable devices such as mobile phones. For such applications, using a stepping motor for a watch is a very effective means.

  However, since the lens driving device linearly drives the lens with higher accuracy, the clearance of the sliding portion is very small in the guide of the operating member, which is often smaller than the general mechanism of the watch. Furthermore, in order to improve the reproducibility of the operation, many of them are provided with a biasing means for the purpose of reducing the clearance of the sliding portion on one side. For this reason, the friction load is large and often requires a larger output than the stepping motor of the conventional timepiece.

  Means for increasing the output include decreasing the clearance between the rotor magnet and the stator and increasing the diameter of the rotor. However, if plastic is molded on the side surface of the rotor magnet as shown in FIG. 10, the clearance between the rotor magnet and the stator inevitably increases, and a sufficient output cannot be obtained.

  In order to prevent this, the plastic rotor true and the rotor magnet are fixed only by the center through-hole surface of the rotor magnet, and the rotor magnet is enlarged to the extent that the plastic on the side surface of the rotor magnet has been eliminated. Two measures can be taken to reduce the clearance and increase the rotor diameter, and the torque of the stepping motor can be increased. However, while the torque was increased, the rotor magnet-rotor true interface is close to the center and the radius is small, and the through hole is a circular hole in the center, and all the interfaces are parallel to the rotation direction. For this reason, the degree of close contact with each other cannot be ensured, and the interface may be peeled off during the step operation of the rotor magnet, which may loosen the rotor magnet and the rotor true. As the torque is increased, the inertial force of the rotor magnet is increased and the rotor magnet is easily loosened. If it is loosened, the rotation of the rotor magnet cannot be transmitted accurately and the reproducibility of the straight movement of the lens may be poor in a lens driving device or the like.

  In addition, there are four belt-like parts on the outer peripheral side of the rotor magnet, and the outermost part is the outermost periphery. Therefore, depending on the molding accuracy, it is easy to cause variations in the inertial force of the rotor, which affects the variations in the performance of the stepping motor. It was.

  In order to solve the above-described problems, a stepping motor according to the present invention includes a magnetized rotor magnet and a power transmission unit that rotates around a rotation axis, and a coil that generates a magnetic field by supplied electric energy. And a rotor magnet that transmits power to the power transmission unit through the connection hole, and the connection hole is in a plane perpendicular to the rotation axis. The shape has a non-rotating shape whose distance from the rotation axis is not constant.

  Furthermore, the stepping motor of the present invention includes a rotor having magnetized rotor magnet and a power transmission unit that rotates around the rotation axis, a coil that generates a magnetic field by supplied electric energy, and a magnetic path of the magnetic field. In the stepping motor having a stator composed of a yoke that constitutes the rotor magnet, the rotor magnet transmits power to the power transmission portion through a plurality of connection holes provided in the rotor magnet, and at least one connection hole includes a rotation axis. There is no position.

  In these inventions, it is not necessary to dispose resin on the outer peripheral side surface of the rotor magnet and use this to transmit power to the power transmission unit, so that the rotor magnet can be made larger and the gap between the yoke and the rotor magnet can be made as small as possible. Therefore, a stepping motor having a high torque can be realized without changing the size of the stepping motor. Further, it is possible to prevent looseness of the rotor magnet that outputs high torque and the power transmission unit, and to transmit power with high accuracy. Furthermore, since it is not necessary to partially form resin on the outer periphery of the rotor magnet, the dimensional accuracy of the outer periphery of the rotor magnet, which has a large influence on the rotor inertial force, is higher than that of partial resin molding, If it is strong, the characteristic variation of a stepping motor can be reduced.

According to a preferred embodiment of the present invention, the stepping motor is mounted on one surface of the base plate, and includes a coil block having a coil disposed along the base plate. The yoke has a magnetic path other than the end connected to the coil block. The portion is provided so as not to overlap the coil block, and the rotor is disposed in the rotor through-hole of the yoke. In the present invention, the stepping motor is configured as a flat type, and is a thin stepping motor. A simple electronic device can be configured.

  Moreover, in the preferable form of this invention, the rotation stop shape provided in the rotor magnet of the stepping motor is a shape which has an angle | corner.

  In the present invention, it is possible to efficiently transmit the rotational force to the power transmission unit using the corners of the rotor magnet and prevent the rotor magnet and the power transmission unit from being separated.

  In a preferred embodiment of the present invention, the anti-rotation shape provided on the rotor magnet of the stepping motor is a shape that overlaps the center of the inscribed circle and the rotation axis.

  In the present invention, the connection hole can be used as a guide when the outer shape of the rotor magnet is machined into a highly accurate circular diameter, and as a result, variation in rotor operation is reduced.

  Moreover, in the preferable form of this invention, the rotation stop shape provided in the rotor magnet of the stepping motor is a shape which becomes symmetrical with respect to the rotation axis.

  In a preferred embodiment of the present invention, the anti-rotation shape provided in the rotor magnet of the stepping motor has at least one plane that includes the rotation axis and is plane-symmetrical, and is polarized along this plane. ing.

  In these inventions, since the shape of each pole region of the rotor magnet is equal, variation in operating characteristics for each pole is reduced.

  In a preferred embodiment of the present invention, the stepping motor has axial holding portions for holding the rotor magnet in the axial direction on the upper and lower surfaces of the rotor magnet, and these are integrally formed by molding.

  In this invention, the rotor magnet is formed integrally with the axial holding part by insert molding, and the power transmission part and the rotating shaft are integrated through the axial holding part, thereby realizing a low-cost manufacturing stepping motor. can do.

  Further, an electronic device using the stepping motor of the present invention has an operation unit that functions by the operation of the power transmission unit using the stepping motor of the present invention.

  According to the present invention, it is possible to provide an electronic device that can operate stably with high accuracy even with a high load by using a stepping motor with high torque and high accuracy.

  According to the present invention, the rotor magnet is integrated with the rotor true by insert molding, and the rotor magnet is enlarged and the gap between the rotor magnet and the stator is narrowed while the rotor magnet and the rotor are closely bonded to each other. Therefore, it is possible to provide a stepping motor with high output and high reliability and an electronic device using the stepping motor.

  A first embodiment of the present invention will be described with reference to FIGS.

  FIG. 1A is a plan view of a stepping motor 26 of the present invention and an electronic device 21 using the stepping motor 26, for example, a lens driving device.

  FIG. 1B is a cross-sectional view of the electronic device 21 using the stepping motor 26 and the stepping motor 26 of the present invention along the F2-F2 cut surface in FIG.

  An electronic device denoted by reference numeral 21 in FIGS. 1A and 1B is a lens driving device that drives an optical component, for example, a lens, and is mounted on a thin electronic device such as a card-type digital camera or a camera-equipped mobile phone. The lens driving device 21 includes a circuit board 22, a base plate 23, a gear support 24, a cover 25, a stepping motor 26, optical components such as a lens barrel 27, a moving means 28, and a reduction gear train 29. is doing.

  The circuit board 22 has an image pickup device 30 such as a CCD or CMOS mounted on one surface thereof. A base plate 23 is attached to the one surface of the circuit board 22. The base plate 23 is, for example, rectangular, and has a hole 23e for accommodating the imaging element 30 and allowing the lens barrel 27 to be disposed at one end portion in the longitudinal direction. A gear support 24 is disposed at the other end portion of the base plate 23 in the longitudinal direction and is opposed to this portion at a predetermined distance. A cover 25 is attached over the gear support 24 and the longitudinal end portion of the base plate 23. The cover 25 has a window hole 25 a that faces the incident surface of the lens barrel 27.

  The gear support 24 also serves as a member that fixes the stepping motor 26 between the base plate 23 and the stepping motor 26. The gear support 24 is fixed to the base plate 23 via a plurality of, for example, three attachment shafts 31 attached by screws 32 fastened from the back side.

  The stepping motor 26 is a two-pole motor having a step angle of 180 °, for example, and includes a coil block 35, a yoke 36, and a rotor 37 as shown in FIG. The coil block 35 and the yoke 36 form a stator.

  The coil block 35 has an iron core 38 and an excitation coil 39. The iron core 38 is integrally formed with yoke coupling portions 38b and 38c at both ends in the longitudinal direction of the core portion 38a (see FIG. 1). As a preferred example, the pair of coil blocks 35 are provided so that the rotational speed when the rotor 37 is rotated forward and when the rotor 37 is rotated backward is the same. In particular, in the present embodiment, since the yoke connecting portions 38c are shared in order to integrate these coil blocks 35, the yoke connecting portions 38b are respectively provided on both sides of the mounting portion 38c via the core portions 38a. Yes. The exciting coils 39 are respectively wound around the core portion 38a.

  The yoke 36 for guiding the magnetic flux generated by the excitation of the exciting coil 39 has a flat plate shape and has end portions 36b and 36c connected to the yoke connecting portions 38b and 38c. The pair of end portions 36b are respectively connected to the yoke connecting portion 38b, and the other one end portion 36c located between the pair of end portions 36b is connected to the yoke connecting portion 38c. The magnetic path portion 36 a excluding the end portions 36 b and 36 c of the yoke 36 protrudes to the side of the coil block 35 without overlapping the coil block 35. A rotor through hole 40 is formed in the magnetic path portion 36a.

  A gap 41 is formed between the magnetic path portion 36 a and the coil block 35. At least part of the side surface of the exciting coil 39 faces the gap 41. Reference numeral 42 in FIG. 1 indicates a recess in the magnetic path portion 36 a provided around the rotor through hole 40. Between the recess 42 and the rotor through hole 40 and between the air gap 41 and the rotor through hole 40, the magnetic path cross-sectional area is extremely small, and magnetic saturation is very easily performed. For this reason, the inner peripheral surface of the rotor through-hole 40 is substantially divided at a portion where the magnetic path cross-sectional area is minimal. Each of the divided areas functions as a magnetic pole tip, and an S pole or an N pole appears at the magnetic pole tip every time a drive pulse is applied to the exciting coil 39.

  A rotor 37 is disposed in the rotor through hole 40. The rotor 37 is composed of a rotor true 61 and a rotor magnet 59 magnetized in two poles (S pole and N pole). The rotor magnet 59 is magnetized with different polarities for each predetermined region adjacent in the circumferential direction. Therefore, the stepping motor 26 has a step angle of 180 ° by the magnetic action between the magnetic pole end and the magnetic pole of the rotor 37 every time a driving pulse is applied to the exciting coil 39 via a motor driver (not shown). It is rotated. A driving gear 43 is formed integrally with the rotor 37. Both ends of the rotating shaft 44 of the rotor 37 are rotatably supported by the base plate 23 and the gear support 24. The rotor 37 has a gap with the rotor through-hole 40 to prevent generation of friction loss due to contact.

  The stepping motor 26 is fixed to the base plate 23 via the mounting shaft 31 and the screw 32. In this case, the mounting shaft 31 is passed through the yoke connecting portion 38b and the end portion 36b of the yoke 36 connected to the yoke connecting portion 38b or the yoke connecting portion 38c and the end portion 36c of the yoke 36 connected thereto. Can be fixed with the stepping motor 26 sandwiched between the base plate 23 and the gear support 24.

  The lens barrel 27 has a plurality of lenses 27a housed therein. A lens barrel holder 45 is screwed onto the outer periphery of the lens barrel 27. A plurality of, for example, a pair of sliding portions 45a are preferably provided on the outer periphery of the lens barrel holder 45 so as to substantially correspond to the radial direction, and these sliding portions 45a are provided with shaft sliding elements such as through holes or concave grooves. Have. Around the lens barrel 27, a plurality of guide shafts 46 are attached over the base plate 23 and the cover 25, and these guide shafts 46 are individually passed through the shaft sliding elements. Accordingly, the lens barrel 27 is supported so as to be movable along the plurality of guide shafts 46 in a direction facing the image sensor 30 and coming into contact with and separated from the image sensor 30. By this movement, the focusing operation of the lens barrel 27 with respect to the image sensor 30 is performed.

  A coil spring 47 is wound around one guide shaft, for example, one guide shaft 46 close to the stepping motor 26. The coil spring 47 is sandwiched between one sliding portion 45a through which the one guide shaft 46 penetrates and the base plate 23, and attaches the lens barrel 27 in a direction away from the image sensor 30 via the lens barrel holder 45. It is fast.

  The moving means 28 includes a feed screw 51 and a nut member 52. As shown in FIG. 2, the feed screw 51 forms a part of the gear shaft 53. The gear shaft 53 passes through the gear support 24 and the outward projecting portion 48 facing the gear support 24 in the vicinity thereof, and both ends thereof are rotatably supported by the base plate 23 and the cover 25. The nut member 52 is fixed to the outward projecting portion 48, and the feed screw 51 is engaged with the nut member 52. Therefore, when the gear shaft 53 is rotated, the rotation is converted by the moving means 28 into a movement that moves the lens barrel holder 45 along the axial direction of the feed screw 51. Therefore, the lens barrel 27 is moved along the optical axis O.

  The moving means 28 and the rotor 37 are connected via a reduction gear train 29 arranged on one surface side of the base plate 23. As shown in FIG. 1, the reduction gear train 29 has a plurality of, for example, first to third reduction gears 55 to 57 made of spur gears. The first reduction gear 55 is engaged with the drive gear 43 of the rotor 37, and the second reduction gear 56 rotated together with the first reduction gear 55 is engaged with the third reduction gear 57. The third reduction gear 57 is attached to the gear shaft 53. Both ends of a gear shaft 58 that supports the first reduction gear 55 and the second reduction gear 56 are rotatably supported by the base plate 23 and the cover 25. Therefore, when the stepping motor 26 is driven and the rotor 37 is rotated, the rotation is decelerated by the reduction gear train 29 and given to the moving means 28.

  FIG. 2 is a cross-sectional view taken along a plane including the rotation axis A of the rotor 37. FIG. 3 is a cross-sectional view taken along a neutral line with respect to the axial direction of the rotor magnet 59.

  The rotor 37 is composed of a rotor true 61 made of resin and a columnar rotor magnet 59 magnetized in two poles (S pole and N pole). The rotor true 61 includes a rotation shaft 44 as a rotation guide for rotatably supporting the rotor, a drive gear 43 as a power transmission unit, and rotor magnet holding portions 60 and 62 that connect the rotor magnet 59 and the rotor true 61. Has been.

  The rotor magnet 59 is insert-molded into the rotor true 61 so that the upper and lower surfaces of the rotor magnet 59 are filled with the rotor magnet fixing portions 60a and 60b and the connection hole 63 and the connection hole 63 provided near the center of the rotor magnet 59. It is held by a rotor magnet fixing portion 62 having a shape. Further, the rotating shaft 44a, the drive gear 43, the rotor magnet fixing portion 60a, the rotor magnet fixing portion 60b, and the rotating shaft 44b are connected via the rotor magnet fixing portion 62.

  As shown in FIG. 3, the shape of the connection hole 63 is formed by four straight portions 63a, b, c, d and arc portions 63e, f, g, h having substantially the same radius at the center of the rotation axis A, and has eight corners. It has a shape. However, these corners may be slightly rounded for manufacturing. In this shape, the distance from the rotation axis A is not constant, but is a rotation stop shape. For this reason, since the direction of the interface between the rotor fixing portion 62 and the connection hole 63 is different from the direction of rotation of the rotor 37, out of the rotational force around the rotation axis A generated at the interface due to the inertia force of the rotor magnet 59. If the component acting in the direction parallel to the interface is the peeling force, this peeling force is reduced and the peeling is difficult. Further, even if the separation occurs, the rotor magnet fixing portion 62 and the connection hole 63 are caught, and therefore the relative movement between the rotor magnet 59 and the rotor true 61 cannot occur unless they are destroyed. Therefore, the motion of the rotor magnet 59 can be accurately transmitted to the rotor true 61, and the drive gear 43 can be rotated with high accuracy.

  In addition, the rotor magnet fixing portion 60 has an area larger than that of the connection hole 63, and increases the fixing area with the upper and lower surfaces of the rotor magnet 59. For this reason, the adhesion force between the rotor magnet 59 and the rotor true 61 can be further increased. The rotor magnet fixing portion 60 has a function of an axial direction holding portion that determines the vertical position of the rotor magnet 59.

  In the conventional configuration, since the outer peripheral side surface of the rotor magnet is used to closely adhere the resin to the rotor true, at least the thickness of the resin formed on the side surface of the rotor magnet is between the rotor magnet and the rotor through-hole. In consideration of manufacturing and assembly errors, a gap must be provided so that the resin formed on the rotor through-hole and the rotor magnet does not contact each other. Therefore, there is a limit in reducing the distance between the rotor through hole and the rotor magnet and further increasing the rotor magnet diameter.

  However, in the first embodiment of the present invention, the diameter of the rotor magnet 59 can be increased by the thickness of the resin formed on the side surface of the conventional rotor magnet. For example, since the thickness of the resin formed on the side surface of the rotor magnet is conventionally at least about 0.1 mm, the diameter of the rotor magnet 59 can be increased by 0.2 mm or more than before, and the output torque can be increased. An increase is possible.

  Furthermore, since the distance between the rotor through hole 40 and the rotor magnet 59 can be reduced by the thickness of the resin formed on the side surface of the conventional rotor magnet, an even higher output torque can be obtained.

  Further, although the torque is increased, the overall size of the stepping motor 26 does not change.

  By the way, it is desirable that the outer peripheral shape of the rotor magnet 59 is a circular shape as much as possible to reduce eccentricity with respect to the rotation axis in order to reduce unevenness of magnetic force, unevenness of inertial force, and the like. In the manufacturing process of the rotor 37, increasing the roundness of the rotor magnet 59 and the accuracy of the eccentricity with respect to the rotation axis A contribute to the improvement of the stepping motor performance. In the present embodiment, the rotor magnet 59 is guided by a cylindrical rod that is in contact with the straight portions 63 a, 63 b, 63 c, 63 d of the connection hole 63, that is, inscribed in the rotation stop shape of the connection hole 63, and the outer periphery of the rotor magnet 59 is By processing by polishing or the like, the roundness is increased, and when the rotor true 61 is formed, the outer periphery of the rotor magnet 59 with high accuracy is guided to form the rotating shaft 44. As a result, it is possible to obtain the rotor 37 with high circularity of the rotor magnet 59 with respect to the rotation axis A and less eccentricity.

  Further, in the conventional rotor, the resin is partially formed on the outer circumferential side surface of the rotor magnet, but in the present invention, it is not necessary to form the resin on the outer circumferential side surface. This makes it possible to reduce variations in stepping motors.

  Further, the rotation stop shape of the connection hole 63 is symmetric with respect to the rotation axis A, that is, point-symmetric. By adopting such a shape, when the rotor magnet 59 is magnetized in two poles, the regions of each other are the same regardless of which direction the magnet is magnetized, thereby reducing variations in rotational characteristics within one rotation. Furthermore, since the anti-rotation shape is point-symmetric, each portion corresponding to the symmetrical position of the anti-rotation shape transmits the rotational force in a balanced manner, so that it does not receive local force and is not easily damaged by fatigue.

  Further, the rotation stop shape of the connection hole 63 is a shape having a plane that includes the rotation axis A and is plane-symmetric. By performing the polarization direction of the rotor magnet 59 along this plane, it is possible to equalize the region shape of each pole and reduce the variation in output characteristics in each pole. For example, the effect can be obtained by performing polarization along a plane connecting the midpoints of the straight line portion 63a and the straight line portion 63c, or performing polarization at the midpoint of the arc portion 63e and the arc portion 63g.

  Further, since the rotor magnet 59 has the connection hole 63 having a rotation prevention shape, the position in the circumferential direction of the rotor magnet 59 can be determined by using the rotation prevention shape at the time of insert molding. Therefore, the polarization positions of the drive gear 43 and the rotor magnet 59 can be accurately positioned with respect to the circumferential direction. As a result, it is possible to accurately determine the start and end of engagement of the teeth of the drive gear engaged within one step operation of the stepping motor, so that the power transmission efficiency is increased or the intermittently driven gear is used as the drive gear. In this case, it is possible to make it mechanically controllable, such as determining when to operate during one step rotation.

  With the above configuration, a stepping motor with high accuracy, high output, and high reliability can be obtained.

  Further, if this stepping motor 26 is used, the torque is high, so that the gap between the guide shaft 46 and the sliding portion 45a is reduced in order to suppress the rattling of the lens in the straight movement of the lens, resulting in a large friction loss there. Even in such a case, a lens driving device capable of stably performing the lens straight-ahead operation can be obtained. Furthermore, a lens driving device having high reproducibility in the straight movement of the lens can be obtained.

  The second embodiment of the present invention is a modification of the structure of the rotor 37 in the stepping motor 26 shown in the first embodiment, and other structures not shown are the same as those of the first embodiment. FIG. 4 shows a second embodiment of the present invention and is a cross-sectional view taken along a neutral line of the rotor magnet 70 of the stepping motor 26.

  The feature of FIG. 4 is that the shape of the connection hole 71 provided in the rotor magnet 70 is formed only by the straight portions 71a, b, c, d and has four corners. Here, the lengths of the respective straight portions are substantially equal and are approximately square. A rotor magnet fixing portion 72 is formed in the connection hole 71 by molding. In the vicinity of the corner of the shape of the connection hole 71, the interface direction of the connection hole 71 and the rotor magnet fixing portion 72 and the rotation direction of the rotor are approximately 45 degrees, so the peeling force is multiplied by cos 45 ° and greatly reduced. Therefore, the rotor magnet fixing portion 72 is more difficult to peel off from the connection hole 71. The polarization is desirably performed, for example, along a line connecting opposite corners or along a line connecting the midpoints of the straight line portion 71a and the straight line portion 71c.

  The third embodiment of the present invention is a modification of the structure of the rotor 37 in the stepping motor 26 shown in the first embodiment, and other structures not shown are the same as those of the first embodiment. FIG. 5 shows a third embodiment of the present invention and is a cross-sectional view taken along a neutral line of the rotor magnet 80 of the stepping motor 26.

  The feature of FIG. 5 is that the shape of a connection hole 81 provided in the rotor magnet 80 is formed by straight portions 81a, b and arcs 81c, d connecting them. This shape is easy to process because there are no corners.

  The fourth embodiment of the present invention is a modification of the structure of the rotor 37 in the stepping motor 26 shown in the first embodiment, and other structures not shown are the same as those in the first embodiment. FIG. 6 shows a fourth embodiment of the present invention and is a cross-sectional view taken along a neutral line of the rotor magnet 90 of the stepping motor 26.

  The feature of FIG. 6 is that a circular connection hole 91 provided in the rotor magnet 90 is provided. Here, two circular connection holes 91a and 91b are provided at positions of contrast with respect to a straight line passing through the rotation axis A, and resin rotor magnet fixing portions 92a and 92b are formed therein by molding. Since the center of each circular shape of the connection holes 91a and 91b is deviated from the rotation axis A of the rotor, the rotation direction and the interface direction of the connection hole 91 and the rotor magnet lake bottom 92 include portions that are not parallel to each other. Can be reduced. Further, since a plurality of portions to be fixed to the rotor magnet through the connection holes are provided, the peeling force can be further reduced. In addition, for example, when a rotational force rotating at the center of the connection hole 91a is generated in the rotor magnet for some reason, the rotor magnet 90 and the rotor true may move relative to each other because the rotor magnet fixing portion 92b supports the rotational force. Absent. Further, since the connection hole 91 has a simple circular shape, the workability is good, and the rotor magnet 90 is symmetrical, so that the balance of inertial force and magnetic density is good.

  Although the connection holes are arranged symmetrically here, any one of them can be provided at the center of the rotor magnet 90. It is also possible to use either one of the connection holes as a hole that stops without being penetrated and to connect the rotary shaft 44a and the rotary shaft 44b using the other hole. Furthermore, the connection hole which does not penetrate can also be provided in a rotor magnet lower surface.

  Here, two connection holes are provided in the rotor magnet 90, but three or more holes may be provided.

  The fifth embodiment of the present invention is a modification of the structure of the rotor 37 in the stepping motor 26 shown in the first embodiment, and other structures not shown are the same as those of the first embodiment. 7 and 8 show a fifth embodiment of the present invention. FIG. 7 is a sectional view taken along a plane passing through the rotation axis A of the rotor 100 of the stepping motor 26. FIG. 8 is an upper surface of the rotor 100 of the stepping motor 26. FIG.

  The rotor 100 is configured by coupling a rotor true 110 and a rotor magnet 101, and the rotor true 110 is integrally configured with a rotating shaft 102, a drive gear 108, and rotor magnet holding portions 103, 104, and 107. . The lower surface of the rotor magnet 101 is held by a rotor magnet holding portion 104, and a connection hole 109 penetrating through the center of the rotor magnet 101 is held by the rotor magnet holding portion 107. Grooves 106 are provided on the upper surface of the rotor magnet 101, and the shape of the upper surface is linear as shown in FIG. 8, and a plurality of grooves 106 extend radially from the rotation axis A. Here, the groove 106 extending to the outer periphery of the rotor magnet 101 is formed in a cross shape. A portion of the rotor magnet holding portion 103 is fitted along the groove portion 106, and the wall surface 106 a of the groove portion 106 extends in a direction substantially perpendicular to the rotation direction, so that the wall surface 106 a passes through the rotor magnet holding portion 103. Thus, the rotational force is efficiently transmitted to the rotor true 110 to prevent the rotor magnet 101 and the rotor true 110 from being separated.

  The present invention is not limited to the above embodiments. For example, the rotor magnet may have not only two poles in the circumferential direction but also more poles, or one polarized in the axial direction. Further, the power transmission unit possessed by the rotor is not limited to gears but may be screws, links, cams, or the like, and the power transmission unit itself may be the final output unit of the electronic device.

  In addition, the stepping motor of the present invention performs not only electronic devices such as a lens driving device for autofocus and zooming, but also driving of operating parts of an optical component such as a shutter, an aperture, a mirror and a prism, and a camera swing. It can also be used for optical modules, clocks, printers, robots, pumps, and the like.

  Each embodiment can also be combined. For example, the first embodiment or the fourth embodiment may be combined with the fifth embodiment, and the shape of the connection hole may be a shape such as the connection hole 63 or a plurality of connection holes, and a groove portion such as the groove portion 106 may be provided on the upper surface of the rotor. It is done.

(A) The top view which shows the electronic device using the stepping motor which concerns on 1st Embodiment of this invention in the state which removed the cover and the gear support.

(B) Sectional drawing shown along the F2-F2 line | wire in FIG.1 (a) of the electronic device which concerns on 1st Embodiment.
Sectional drawing shown along the surface containing the rotating shaft line of the rotor of the stepping motor with which the electronic device which concerns on 1st Embodiment is provided. Sectional drawing which shows the rotor of the stepping motor with which the electronic device which concerns on 1st Embodiment is provided along the center of a rotor magnet perpendicular | vertical to a rotating shaft. Sectional drawing which shows the rotor of the stepping motor which concerns on 2nd Embodiment along a rotor magnet center perpendicular | vertical to a rotating shaft Sectional drawing which shows the rotor of the stepping motor which concerns on 3rd Embodiment along a rotor magnet center perpendicular | vertical to a rotating shaft Sectional drawing which shows the rotor of the stepping motor which concerns on 4th Embodiment along a rotor magnet center perpendicular | vertical to a rotating shaft Sectional drawing which shows the rotor of the stepping motor which concerns on 5th Embodiment along the surface containing a rotating shaft The top view which looked at the rotor of the stepping motor which concerns on 6th Embodiment from the rotating shaft direction upper surface The top view which shows the stepping motor which concerns on a prior art example. Sectional drawing and top view which show the rotor shape of the stepping motor which concerns on a prior art example.

Explanation of symbols

21 ... Lens driving device (electronic equipment)
DESCRIPTION OF SYMBOLS 22 ... Circuit board 23 ... Base plate 24 ... Gear support 25 ... Cover 26 ... Stepping motor 27 ... Lens barrel (optical component)
O ... Optical axis of lens barrel 28 ... Moving means 29 ... Reduction gear train 30 ... Imaging device 35 ... Coil block 36 ... Yoke 36a ... Magnetic path portion of yoke 36b, 36c ... End of yoke 37, 100 ... Rotor A ... Rotor Axis of rotation 38 ... iron core 38a ... core core portion 38b, 38c ... yoke connection portion of iron core 39 ... exciting coil 40 ... rotor through hole 41 ... gap 43 ... drive gear 45 ... lens barrel holder 45a ... slide of lens barrel holder Portion 46 ... Guide shaft 48 ... Outward projecting portion 51 ... Feed screw 52 ... Nut member 53, 58 ... Gear shaft 55, 56, 57 ... Reduction gear 59, 70, 80, 90, 101 ... Rotor magnet 61 ... Rotor true 60 62, 72, 82, 92, 103, 104, 107 ... Rotor magnet holding part 63, 71, 81, 91, 109 ... Connection hole 106 ... Groove part

Claims (9)

A rotor including a magnetized rotor magnet and a power transmission unit that rotates around a rotation axis; a coil that generates a magnetic field by supplied electric energy; and a stator that includes a yoke that forms a magnetic path of the magnetic field. In stepping motors
The rotor magnet transmits power to a power transmission portion through a connection hole provided in the rotor magnet, and the shape of the connection hole in a plane perpendicular to the rotation axis is a constant distance from the rotation axis. A stepping motor having a non-rotating stop shape.   The stepping motor according to claim 1, wherein the rotation stop shape is a shape having a corner.   The stepping motor according to claim 1, wherein a center of the inscribed circle of the rotation stop shape substantially overlaps the rotation axis.   The stepping motor according to claim 1, wherein the rotation stop shape is a shape that is symmetrical with respect to the rotation axis.   5. The anti-rotation shape includes at least one plane that includes a rotation axis and is symmetrical with respect to a plane, and is polarized along the plane. Stepping motor. A rotor having a magnetized rotor magnet and a power transmission unit and rotating around the rotation axis; a coil for generating a magnetic field by the supplied electric energy; and a stator comprising a yoke constituting the magnetic path of the magnetic field In stepping motors
The rotor magnet transmits power to a power transmission unit through a plurality of connection holes provided in the rotor magnet, and at least one of the connection holes is provided at a position not including the rotation axis. Stepping motor.   7. The rotor magnet according to claim 1, further comprising two axial holding portions for holding the rotor magnet in an axial direction on each of the upper and lower surfaces of the rotor magnet, which are integrally formed by molding. Stepping motor described in 1.   The stepping motor is mounted on one surface of a base plate, and includes a coil block having the coil disposed along the base plate. The yoke has a magnetic path portion other than an end connected to the coil block. The stepping motor according to claim 1, wherein the stepping motor is provided without being overlapped with a block, and the rotor is disposed in a rotor through hole of the yoke.   The electronic device using the stepping motor according to any one of claims 1 to 8, further comprising an operation unit that functions by an operation of the power transmission unit.

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