JP2006158023A - Stepping motor and lens unit - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a stepping motor in which running torque of the rotor can be increased while reducing the size. <P>SOLUTION: The stepping motor comprises a rotor 10 consisting of a permanent magnet, and a stator 20 consisting of two pairs of pole pieces 30, 40, 50, 60 provided with pairs of magnetic poles 31, 41, 51, 61 having inner ends opposing while holding the rotor 10 between, two yoke pieces 35, 55 connecting the outer ends of the two pairs of pole pieces 30, 40, 50, 60, and two coils 37, 57 wound around two yoke pieces 35, 55, respectively. Two coils 37, 57 are extended in the direction intersecting the rotating axis of the rotor 10 perpendicularly and arranged to overlap each other. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a stepping motor and a lens device.

  Conventionally, there has been provided a stepping motor including a rotor made of a permanent magnet and a stator for rotating the rotor. In general, the stator of such a stepping motor has a plurality of pairs of magnetic poles. The magnetic pole is constituted by one end of the magnetic pole piece, and the other end of the pair of magnetic pole pieces is connected by the yoke piece. Then, a conductive wire is wound around the yoke piece to form a coil.

For example, in the one shown in Patent Document 1, three magnetic pole pieces are provided around the rotor and two yoke parts are provided, and a coil is formed by winding a conducting wire around these yoke parts. Has been proposed. Further, in the one shown in Patent Document 2, four pole pieces are provided around the rotor and two yoke parts are provided, and a coil is formed by winding a conducting wire around these yoke parts. Has been proposed.
Japanese Patent Publication No.2-2382 Japanese Patent No. 3333544

  Here, when a stepping motor is configured as shown in Patent Document 1, a part of the magnetic pole piece is connected, so that the stator can be configured to be small in terms of a planar size. That is, the stepping motor as a whole can be made small, but at the same time, the volume of the provided coil can only be made small. Therefore, since the winding amount of the conducting wire forming the coil is small, there is a problem that the magnetic force of the magnetized magnetic pole becomes small.

  On the other hand, when the stepping motor is configured as shown in Patent Document 2, the coil volume can be increased. However, the planar size of the stator is also increased, and there is a problem that the entire stepping motor is increased.

  The present invention has been made in view of such circumstances, and is a stepping motor capable of increasing the rotational torque of the rotor while being configured to be small in size, and quickly suitable even though being configured to be small in size. An object of the present invention is to provide a lens device that can move the lens.

In order to solve the above problems, the present invention provides a stepping motor and a lens apparatus as described below.
A stepping motor according to the present invention includes a rotor made of a permanent magnet and a stator that rotates the rotor, and the stator is spaced at a predetermined angle in the circumferential direction with an interval between the rotor and the rotor. And two pairs of magnetic pole pieces each having a pair of magnetic poles facing each other with the rotor interposed therebetween, and the outer ends of the two pairs of magnetic pole pieces. A stepping motor comprising two yoke pieces formed by connecting the two yoke pieces, and two coils formed by being wound around each of the two yoke pieces. It extends in a direction orthogonal to the axial direction, and is arranged at a position overlapping each other.

  In the stepping motor according to the present invention, the two coils for magnetizing the magnetic poles of the magnetic pole pieces are each extended in a direction perpendicular to the rotation axis direction of the rotor and arranged at positions overlapping each other. Therefore, the stator is configured as if the pole piece, the yoke piece, and the coil formed by being wound around the yoke piece constitute a hierarchy with respect to the surface constituted by the pole piece. The Therefore, the stator is configured so that its bulkiness is suppressed, whereby the size as a stepping motor can be reduced. And by being comprised hierarchically, it becomes possible to comprise the volume of the coil provided in the yoke piece simultaneously larger than before. That is, the amount of winding of the conductive wire that also leads to the volume of the coil can be increased, so that the rotational torque of the rotor can also be increased.

  In the stepping motor according to the present invention, one yoke piece is disposed on one side in the rotation axis direction of the rotor with the two pairs of magnetic pole pieces interposed therebetween, and the other side in the rotation axis direction of the rotor. On the other hand, another yoke piece is arranged.

  In the stepping motor according to the present invention, the yoke pieces are respectively disposed on both sides in the rotation axis direction of the rotor with the two pairs of magnetic pole pieces interposed therebetween. In other words, a three-layer structure is formed, in which two pairs of magnetic pole pieces are used as a central layer, with one yoke piece above it and another yoke piece below it. In each of these two yoke pieces, a conductive wire is wound to form a coil. Even when these coils are superposed on each other, two pairs of magnetic pole pieces are interposed between them, so that the volume (diameter) of the coil is increased until it reaches the thickness of the magnetic pole pieces. Can be configured. As a result, it is possible to increase the winding amount of the lead wire for the purpose of increasing the rotational torque of the rotor. Accordingly, the bulk of the stator is suppressed, and the size of the stepping motor can be reduced. That is, the amount of winding of the conductive wire that also leads to the volume of the coil can be increased, so that the rotational torque of the rotor can also be increased.

  The stepping motor according to the present invention is characterized in that the magnetic pole pieces adjacent to each other are connected and integrated with each other by a thin portion.

  In the stepping motor according to the present invention, the magnetic pole pieces adjacent to each other are connected and integrated with each other by a thin portion provided in the vicinity of the magnetic pole, so that the rigidity of the entire stepping motor is also increased. In addition, the magnetized magnetic force is unlikely to affect adjacent magnetic poles due to its thin wall. Therefore, it is possible to obtain a stepping motor in which the rotor can preferably rotate.

  In the stepping motor according to the present invention, a concave portion or a convex portion opposed to each other with the rotor interposed therebetween is provided on the inner circumference of the plurality of magnetic pole pieces opposed to the outer circumference in the radial direction of the rotor. And

For example, when the distance between the outer periphery of the rotor and the inner periphery of the stator is constant, such as when the inner periphery of the stator facing the outer periphery of the rotor is formed in an arc shape, the magnetic poles are magnetized. If not, the rotor cannot rest stably.
In such a case, in the stepping motor according to the present invention, for example, when a concave portion is formed on the inner periphery of the pole piece constituting a part of the stator, the concave portion is included in the inner periphery. The spaced apart part is the most spaced apart from the rotor. As a result, when the magnetic pole is not magnetized, the rotor is rotated so that the magnetic pole of the rotor moves away from the separated part, that is, close to another part different from the separated part. At that position, the rotor is stably stationary. Therefore, when the magnetic pole is not magnetized, the rotor can be stably stationary at the stationary position.

  On the other hand, when a convex part is formed in the inner periphery of the magnetic pole piece which comprises a part of stator, the convex part is taken as the proximity | contact part nearest to the rotor among this inner periphery. As a result, when the magnetic pole is not magnetized, the rotor rotates so that the magnetic pole of the rotor approaches the adjacent portion, that is, away from another portion different from the adjacent portion, At that position, the rotor is stably stationary. Therefore, when the magnetic pole is not magnetized, the rotor can be stably stationary at the stationary position.

  In the stepping motor according to the present invention, one pole piece of the pair of magnetic pole pieces is arranged on the same axis as the axis of the pole pieces of a different set, and is on an axis parallel to the axis. In addition, another pole piece in a different set and another pole piece paired with the pole piece are arranged.

  In the stepping motor according to the present invention, different sets of magnetic pole pieces are arranged on two axes arranged in parallel as new sets. Therefore, the pole pieces constituting the stator are arranged without being bulky around the rotor, and the size of the stator can be reduced. And thereby, the magnitude | size as a stepping motor can also be comprised small.

  A lens device according to the present invention is a lens device including the stepping motor according to the above invention, wherein the lens is provided adjacent to the stepping motor, one end is engaged with the rotation shaft of the rotor, and the other end is And an advancing / retracting mechanism that engages with the lens and moves the lens back and forth.

  In the lens apparatus according to the present invention, the lens is moved forward and backward by the stepping motor having a large rotational torque of the rotor while being configured to be small in size. A lens device that can be advanced and retracted can be obtained.

  According to the stepping motor of the present invention, the rotational torque of the rotor can be increased while the size is small. In addition, according to the lens device of the present invention, the lens can be quickly and suitably moved while being small in size.

  Hereinafter, the best embodiment of the stepping motor according to the present invention and the lens apparatus including the stepping motor will be described with reference to FIGS. 1 is a perspective view of a stepping motor according to the present invention, FIG. 2A is a top view of the stepping motor of FIG. 1, FIG. 2B is an enlarged top view of a thin portion, and FIG. 3 is a side view of FIG. 4 is a cross-sectional view taken along the line AA in FIG. 2, and FIG. 5 is a view showing rotation of the rotor.

  The stepping motor 1 shown in FIG. 1 is roughly composed of a rotor 10 and a stator 20. Of the rotor 10 and the stator 20, first, the rotor 10 will be described. As shown in FIG. 2 (a), the rotor 10 is made of a permanent magnet formed in a columnar shape. The center of the cross-sectional circle is a rotating shaft 11, and magnetic poles 13 and 14 each having an N pole and an S pole are provided at 180 degrees on the outer circumferential surface 12 in the radial direction of the cross-sectional circle orthogonal to the direction of the rotating shaft 11. Is. The axis Z of the rotating shaft 11 is the rotating axis of the rotor 10.

  Further, on the outer side of the outer peripheral surface 12 in the radial direction of the rotor 10, magnetic poles 31, 41, 51, 61 are provided so as to surround the rotor 10 at an appropriate interval so as not to contact the rotor 10. The stator 20 includes the pole pieces 30, 40, 50 and 60. The magnetic pole pieces 30, 40, 50, 60 are made of a soft magnetic material and are formed in a rectangular shape as shown in FIG. Further, the magnetic pole pieces 30, 40, 50, 60 are arranged at positions obtained by dividing 360 degrees around the rotor 10 by 90 degrees through thin portions 33, 43, 53, 63 described later. It has become a thing.

  The four magnetic poles 31, 41, 51, 61 are constituted by inner ends of the magnetic pole pieces 30, 40, 50, 60, and more specifically, face the outer peripheral surface 12 in the radial direction of the rotor 10. It is set as the inner peripheral surface 21. The four magnetic poles 31, 41, 51, 61 are magnetized by coils 37, 57 provided on yoke pieces 35, 55 described later. The outer ends of the magnetic pole pieces 30, 40, 50, 60 opposite to the inner ends are connection ends 32, 42, 52, 62 connected to yoke pieces 35, 55, which will be described later. Yes.

  Next, the arrangement positions of the magnetic pole pieces 30, 40, 50, 60 will be described. A central axis extending in the rectangular longitudinal direction of the first magnetic pole piece 30 and a central axis extending in the rectangular longitudinal direction of the third magnetic pole piece 50; Are arranged on the first axis X which is the same axis. Further, the central axis extending in the rectangular longitudinal direction of the second magnetic pole piece 40 and the central axis extending in the rectangular longitudinal direction of the fourth magnetic pole piece 60 are arranged on the second axis Y that is the same axis. . And this 1st axis line X and the 2nd axis line Y are comprised so that it may mutually become parallel. That is, the first magnetic pole piece 30 and the third magnetic pole piece 50 are configured to be arranged in parallel with the second magnetic pole piece 40 and the fourth magnetic pole piece 60.

  Next, the shape and the like of these magnetic pole pieces 30, 40, 50, 60 will be described. Each of the magnetic pole pieces 30, 40, 50, 60 has a square cross section as shown in FIGS. The magnetic pole pieces 30, 40, 50, and 60 are provided on the same plane. That is, the lengths of the first magnetic pole piece 30 and the third magnetic pole piece 50 arranged on the first axis X (length in the direction of the axis X) are formed to be equal to each other. The length of each of the second magnetic pole piece 40 and the fourth magnetic pole piece 60 arranged on the second axis Y (length in the direction of the axis Y) is approximately half the length. It has become. In other words, the lengths of the second magnetic pole piece 40 and the fourth magnetic pole piece 60 (the length in the axis Y direction) arranged on the second axis Y are the first magnetic pole pieces 30 arranged on the first axis X. And the length of the third magnetic pole piece 50 (the length in the direction of the axis X) is about twice as long.

  Further, in the vicinity of the magnetic poles 31, 41, 51, 61, it is formed in a thin shape that constitutes a part of the inner peripheral surface 21 and connects the magnetic pole pieces 30, 40, 50, 60 adjacent to each other. The thin-walled portions 33, 43, 53, and 63 are provided. That is, the first magnetic pole piece 30 is connected to the fourth magnetic pole piece 60 through the thin portion 33, the fourth magnetic pole piece 60 is connected to the second magnetic pole piece 40 through the thin portion 63, and the second magnetic pole piece The piece 40 is connected to the third magnetic pole piece 50 through a thin portion 43, and the third magnetic piece 50 is connected to the first magnetic pole piece 30 through a thin portion 53. As a result, the magnetic pole pieces 30, 40, 50, 60 adjacent to each other are connected to each other so as to be integrated in the same plane.

  Next, the details of the configuration of the thin portions 33, 43, 53, 63 will be described. The four thin portions 33, 43, 53, 63 are formed so as to divide the inner peripheral surface 21 (magnetic poles 31, 41, 51, 61) of the stator 20 by 90 degrees, Each has the same configuration. Therefore, only the thin portion 33 will be described.

  As shown in FIG. 2 (b), the thin portion 33 includes a notch portion 33a in which the magnetic pole piece 30 and the like are cut out from the outside, and a separation portion 33b in which the pole piece 30 and the like are cut out from the inside. It is constituted by. The notch 33a is formed as a groove having a semicircular cross section at the tip thereof from the outside toward the inner peripheral surface 21. The separating portion 33b is configured as a groove having a semicircular cross-section at the tip thereof from the inner peripheral surface 21 outward. Similarly, in the other thin-walled portions 43, 53, and 63, notched portions 43a, 53a, and 63a that are notched from the outside, and spaced-apart portions that are formed by cutting the inner peripheral surface 21 43b, 53b, 63b. The spacing portions 33b, 43b, 53b, and 63b correspond to recesses that face each other across the rotor 10 according to the present invention (claim 4). By providing the thin portions 33, 43, 53, 63, the magnetic pole pieces 30, 40, 50, 60 are integrated with each other, and the magnetic poles 31, 41, 51, 61 are integrated. It also plays a role of suitably dividing.

  Next, the yoke pieces 35, 55 connected to the connection ends 32, 42, 52, 62 of the magnetic pole pieces 30, 40, 50, 60 will be described. That is, the yoke pieces 35, 55 connect the two connection ends 32, 42, 52, 62 to each other. Specifically, the yoke pieces 35, 55 are connected to the first connection end 32 of the first magnetic pole piece 30 and the first connection end 32. The first yoke piece 35 that connects the second connection end 42 of the two magnetic pole pieces 40, the third connection end 52 of the third magnetic pole piece 50, and the fourth connection end 62 of the fourth magnetic pole piece 60 are connected. The second yoke piece 55 is formed. The first yoke piece 35 is provided above the four magnetic pole pieces 30, 40, 50, 60 described above in the rotational axis direction of the rotor 10, and the second yoke piece 55 In this case, the four magnetic pole pieces 30, 40, 50, 60 described above are provided below the rotation axis direction of the rotor 10. That is, the first yoke piece 35 and the second yoke piece 55 are provided on the upper surface side and the lower surface side of the pair of magnetic pole pieces 30, 40, 50, 60 as described above.

  Of the yoke pieces 35, 55, first, the details of the first yoke piece 35 will be described. The first yoke piece 35 includes the first magnetic pole piece 30 and the first pole piece 30 as shown in FIG. Two interposed portions 36a, 36b connected to the connecting ends 32, 42 from the two magnetic pole pieces 40 so as to be orthogonal to the axes X, Y, and a yoke portion 36c connecting the interposed portions 36a, 36b It consists of and.

  The interposed portions 36a and 36b will be described. One end portion is fixed to the upper surface of the first connection end 32 of the first magnetic pole piece 30, and in a direction perpendicular to the first axis X and the second axis Y. The 1st intervention part 36a is provided. Even in the second magnetic pole piece 40, one end thereof is fixed to the upper surface of the second connection end 42, and the second intermediate pole piece 40 extends in a direction perpendicular to the first axis X and the second axis Y. An installation part 36b is provided. The first interposed part 36a and the second interposed part 36b are arranged so that the first yoke part 36c attached to the other end of both is parallel to the first axis X and the second axis Y. The length is adjusted. Specifically, the second interposed part 36b is formed longer than the first interposed part 36a by the difference between the first axis X and the second axis Y. Then, the other end portion of the first interposed portion 36a and the other end portion of the second interposed portion 36b are connected, and extend in a direction parallel to the first axis X and the second axis Y, and A first yoke portion 36c that functions as a yoke is provided. Therefore, the stator 20 has a three-layer structure in which the second yoke piece 55 such as the first yoke piece 35 and the magnetic pole piece 30 is displaced from each other in the height direction.

  Next, a coil for magnetizing the magnetic pole 31 etc. of the magnetic pole piece 30 will be described. That is, as shown in the side view of FIG. 3 and the cross-sectional view of FIG. 4, the first yoke portion 36 c is provided with a first coil 37 formed by winding a conducting wire. As shown in FIG. 4, the first coil 37 has a conducting wire wound around the first yoke portion 36 c so that the cross section is substantially square, and the winding amount of the wound coil is as follows. The magnetic pole pieces 30, 40, 50, 60 are wound around the sides so as to reach almost half of the thickness of the magnetic pole pieces 30, 40, 50, 60 (the length of the rotor 10 in the rotation axis direction). Has been configured.

  Also, the yoke piece 55 provided with the coil 57 is provided on the lower surface of the magnetic pole pieces 30, 40, 50, 60 similarly to the yoke piece 35 provided with the coil 37 formed on the upper surface. It is done. That is, the yoke piece 55 is also composed of the interposed portions 56a and 56b and the yoke portion 56c, as described above, and these interposed portions 56a and 56b are connected to the first connection end 52 and the second connection. One end portion is fixed to the end 62, and a yoke portion 56c is connected to both other end portions. The yoke portion 56c is provided with a second coil 57 around which a conducting wire is wound. Even in the second coil 57, as shown in FIG. 4, the conducting wire is wound around the second yoke portion 56c so that the cross section is substantially square, and the winding of the wound coil is wound. The amount of winding is wound on the side of the magnetic pole pieces 30, 40, 50, 60 until it reaches half of the thickness of the magnetic pole pieces 30, 40, 50, 60 (the length of the rotor 10 in the rotation axis direction). Has been configured. That is, the first coil 37 and the second coil 57 are configured to overlap each other.

The stator 20 configured as described above rotates the rotor 10 as follows.
First, the rotation in the positive rotation direction will be described with reference to FIG. FIG. 5A shows the stationary state of the rotor 10. That is, when none of the magnetic poles 31, 41, 51, 61 is magnetized, the rotor 10 has the magnetic poles 13, 14 provided in the radial direction as described above. It stops at a position that avoids the separation portions 33b, 43b, 53b, and 63b provided at the connecting portions of 50 and 60. That is, the rotor 10 faces the space 33b and the space 63b so that the magnetic pole (S pole) 14 is closest to the metal (magnetic material), and the magnetic pole (N pole) 13 Lies toward the space between the spacing portion 43b and the spacing portion 53b so as to be closest to the metal (magnetic material) and is stationary. That is, by providing the separation portions 33b, 43b, 53b, and 63b at the connecting portions of the magnetic pole pieces 30, 40, 50, and 60, a stable stationary position of the rotor 10 is ensured.

  When the first coil 37 provided in the first yoke portion 36c is energized, as shown in FIG. 5B, the magnetic pole 31 of the first magnetic pole piece 30 is magnetized to the S pole, The magnetic pole 41 of the second magnetic pole piece 40 is magnetized to the N pole. In this case, the rotor 10 further includes a magnetic pole (S pole) 14 of the rotor 10 so that the magnetic pole (N pole) 13 of the rotor 10 approaches the magnetic pole 31 magnetized to the S pole as shown in the figure. Is rotated so as to approach the magnetic pole 41 magnetized to the N pole. The magnetic pole 51 of the third magnetic pole piece 50 and the magnetic pole 61 of the fourth magnetic pole piece 60 are not magnetized.

  Next, when the second coil 57 provided in the second yoke portion 56c is energized, as shown in FIG. 5C, the magnetic pole 51 of the third magnetic pole piece 50 is magnetized to the N pole, The magnetic pole 61 of the fourth magnetic pole piece 60 is magnetized to the S pole. In this case, the rotor 10 further includes a magnetic pole (S pole) 14 of the rotor 10 such that the magnetic pole (N pole) 13 of the rotor 10 approaches the magnetic pole 61 magnetized to the S pole as shown in the figure. Is rotated so as to approach the magnetic pole 51 magnetized to the N pole. The magnetic pole 31 of the first magnetic pole piece 30 and the magnetic pole 41 of the second magnetic pole piece 40 are not magnetized.

  When the first coil 37 provided in the first yoke part 36c is energized in the direction opposite to the above-described figure (b), as shown in FIG. The magnetic pole 31 of the magnetic pole piece 30 is magnetized to the N pole, and the magnetic pole 41 of the second magnetic pole piece 40 is magnetized to the S pole. In this case, the rotor 10 further includes a magnetic pole (S pole) 14 of the rotor 10 so that the magnetic pole (N pole) 13 of the rotor 10 approaches the magnetic pole 41 magnetized to the S pole as shown in the figure. Is rotated so as to approach the magnetic pole 31 magnetized to the N pole. The magnetic pole 51 of the third magnetic pole piece 50 and the magnetic pole 61 of the fourth magnetic pole piece 60 are not magnetized.

  And when the 2nd coil 57 provided in the above-mentioned 2nd yoke part 56c is energized in the direction opposite to the above-mentioned figure (b), as shown in Drawing 5 (e), the 3rd above-mentioned pole piece 50 magnetic poles 51 are magnetized to the S pole, and the magnetic pole 61 of the fourth magnetic pole piece 60 is magnetized to the N pole. In this case, the rotor 10 further includes a magnetic pole (S pole) 14 of the rotor 10 so that the magnetic pole (N pole) 13 of the rotor 10 approaches the magnetic pole 51 magnetized to the S pole as shown in the figure. Is rotated to approach the magnetic pole 61 magnetized to the S pole. The magnetic pole 31 of the first magnetic pole piece 30 and the magnetic pole 41 of the second magnetic pole piece 40 are not magnetized.

  In the stepping motor 1 described above, when the rotor 10 is rotated forward, the first and second coils 37 and 57 are energized as described above, and the magnetic poles provided in the magnetic pole pieces 30, 40, 50 and 60. 31, 41, 51, 61 are magnetized, and the rotor 10 is rotated by these magnetic poles 31, 41, 51, 61, but the above procedure is reversed even when the rotor 10 is rotated in the reverse direction. The rotor 10 is preferably rotated by performing the above.

  Thus, the four magnetic pole pieces 30, 40, 50, 60, the yoke pieces 35, 55, and the coils 37, 57 formed by being wound around the yoke portions 36c, 56c of the yoke piece 35 are formed. Since the stator 20 is configured as if it constitutes a hierarchy, the stator 20 is configured so that its bulkiness is suppressed, whereby the size of the stepping motor 1 can be reduced. At the same time, the stepping motor 1 is configured so as to be less bulky, so that it is possible to increase the amount of winding of the wire for the purpose of increasing the rotational torque of the rotor 10. That is, the volume of the coils 37 and 57 provided in the yoke pieces 35 and 55 can be made larger than that of the conventional art.

  Further, since the magnetic pole pieces 30, 40, 50, 60 are connected to each other by the thin portions 33, 43, 53, 63, the magnetic pole pieces 30, 40, 50, 60 are integrated. Not only the position of 60 is determined, but also the rigidity of the stepping motor 1 as a whole is increased. In addition, when any one of the magnetic poles 31, 41, 51, 61 is magnetized, the other adjacent magnetic poles 31, 41, 51, 61 are magnetized by the thin portions 33, 43, 53, 63. Will not be. Therefore, it is possible to obtain a stepping motor in which the rotor 10 can preferably rotate.

  Further, as described above, the inner circumferential spacing portions 33 b, 43 b, 53 b, 63 b of the magnetic pole pieces 30, 40, 50, 60 constituting a part of the stator 20 are the rotors of the inner circumference 21 of the stator 20. 10 is the most separated part from 10. As a result, when the magnetic pole pieces 30, 40, 50, 60 are not magnetized, the magnetic poles 13, 14 of the rotor 10 are separated from the separated portions, that is, the separated portions. The rotor 10 rotates so that the magnetic poles 13 and 14 of the rotor 10 approach other different parts, and the rotor 10 stably stops at that position. Therefore, when the magnetic pole pieces 30, 40, 50, 60 are not magnetized, the rotor 10 can be stably stationary at the stationary position. In addition, since the thin portions 33, 43, 53, and 63 are configured in this manner, the magnetic force of the magnetic poles 31, 41, 51, and 61 provided in the magnetic pole pieces 30, 40, 50, and 60 is different from that of the other magnetic poles. It does not reach the pieces 30, 40, 50, 60.

Furthermore, in the stepping motor 1 according to the present invention, the first magnetic pole piece 30, the second magnetic pole piece 40, the third magnetic pole piece 50, and the fourth magnetic pole piece 60 formed in a rectangular shape are the first magnetic pole piece. On the first axis X where the central axis of 30 and the central axis of the third magnetic pole piece 50 are the same, the central axis of the second magnetic pole piece 40 and the central axis of the fourth magnetic pole piece 60 are the same. It arrange | positions on the 2nd axis line Y used as an axis. Accordingly, the magnetic pole pieces 30, 40, 50, 60 are arranged around the rotor without being bulky. As a result, the stepping motor 1 can be made small, the amount of winding of the conducting wire constituting the coil can be secured, and the magnetic pole can be suitably magnetized.
As described above, according to the stepping motor 1, the size of the stepping motor 1 is reduced, and the rotational torque of the rotor 10 can be increased.

Next, the lens device 100 including the stepping motor 1 configured as described above will be described with reference to FIGS. 6 is a top view of a lens apparatus using the stepping motor of FIG. 1, and FIG. 7 is a schematic side sectional view of the lens apparatus of FIG.
The lens apparatus 100 has a lens barrel 110 installed at a position adjacent to the step motor 1 described above, and a built-in advance / retreat mechanism that engages with the rotor 10 and moves forward and backward. That is, as shown in the schematic side sectional view of FIG. 7, the lens barrel 110 is configured by incorporating a lens unit 111 in which lenses 113 and 114 are fixed to each other into a lens unit frame member 112. The lens unit 111 is movable up and down within the lens unit frame member 112. The lens barrel 110 and the stator 20 are fixedly attached to the outer wall of the lens device 100 by guide shafts 115 and 116 as shown in FIG. The guide shafts 115 and 116 are made of a non-magnetic material so that the magnetic field generated by the stator 20 is preferable. An imaging element 121 that captures the collected light is fixedly provided at a position facing the second lens across the first lens 113.

  The lens device 100 is provided with an advancing / retreating mechanism having one end engaged with the rotor 10 and the other end engaged with the lens unit 111. The details of this advance / retreat mechanism will be described. The rotor 10 is provided with a rotor shaft 15 fitted in the center of a cross-sectional circle. The rotor shaft 15 is provided with a rotor gear 16 that is rotated along the rotor shaft 15 so as to be press-fitted into the rotor shaft 15. Note that both ends of the rotor shaft 15 are fixed and held so that the rotor shaft 15 can rotate. A drive gear 17 that meshes with the rotor gear 16 is provided next to the rotor gear 16. The drive gear 17 is provided with a feed screw 18 that is fixed to the center of the drive gear 17 and extends on the rotation center axis of the drive gear 17. Note that both ends of the feed screw 18 are also fixed and held so that the feed screw 18 is rotatable.

  A nut member 19 is attached to the feed screw 18 so as to project outward in the radial direction of the feed screw 18. The nut member 19 is engaged with an engagement plate portion 117 that protrudes radially outward of the lens unit 111 of the lens barrel 110. Specifically, the engagement plate portion 117 is formed in a plate shape having an upper surface 118 and a lower surface 119, and the upper surface 118 abuts on the lower surface 19a of the nut member 19, and the lower surface 119 has an inner periphery on the guide. The coil spring 120 is fitted into the shaft 116 and is in contact with the upper end of the coil spring 120. Accordingly, the coil spring 120 urges the engagement plate portion 117 to the side of the movable lens 114 (upward in FIG. 6), and suitably holds the nut member 19 and the engagement plate portion 117 in engagement. It has become. In the lens apparatus 100, a photo sensor 122 is provided at a position adjacent to the lens barrel 110 for the purpose of grasping the distance between the lens unit 111 and the image sensor 121.

  The lens device 100 configured as described above drives the stepping motor 1 when imaging the imaging target, and moves the lens unit 111 up and down within the lens unit frame member 112 by the driving force, thereby imaging the imaging target. The body is preferably imaged. Further, since the stepping motor 1 is configured to be small in size, the lens device 100 itself is also configured to be small in size. Further, since the winding amount of the conductive wires of the coils 37 and 57 can be increased, the rotational torque of the rotor 10 can be improved. That is, the lens unit 111 can be moved up and down (back and forth) forward and backward quickly and suitably within the lens unit frame member 112.

In addition, this invention is not limited to said embodiment, In the range which does not deviate from the meaning, an appropriate selection is possible.
For example, in the above-described embodiment, when none of the magnetic poles 31, 41, 51, 61 are magnetized, the rotor 10 is stopped at a stable position (invention). 4), as the concave portions opposed to each other with the rotor 10 interposed therebetween, spaced portions 33b, 43b, 53b, 63b are provided on the inner periphery 21 of the stator 20. However, instead of the separation portions 33b, 43b, 53b, and 63b, the following configuration may be used. That is, convex portions that protrude 90 degrees in the circumferential direction may be formed on the inner periphery 21 of the stator 20. When this convex portion is formed, if none of the magnetic poles 31, 41, 51, 61 is magnetized, the rotor 10 has the magnetic poles 13, 14 provided in the radial direction as described above. Then, it comes to approach the convex part made of this metal (magnetic material), and it will rest stably.

  Further, in the above-described embodiment, the stepping motor 1 constituted by two pairs of magnetic pole pieces in which the magnetic poles are arranged at 90 degrees has been described. However, the present invention is not limited to this embodiment. The stepping motor may be configured by providing magnetic pole pieces so that three pairs of magnetic poles are arranged at 60 degrees each. In this case, if the magnetic pole pieces are arranged on three common axis lines parallel to each other as in the above-described embodiment, the overall configuration can be reduced. In such an example, the thin-walled portion 33 or the like (the notch portion 33a or the like and the separation portion 33b or the like) is provided at a connecting portion between the adjacent magnetic pole pieces.

1 is a perspective view of a stepping motor according to the present invention. It is a top view of the stepping motor of FIG. FIG. 3 is a side view of FIG. 2. It is AA sectional drawing of FIG. It is a figure which shows rotation of a rotor. It is a top view of the lens apparatus using the stepping motor of FIG. FIG. 7 is a schematic side cross-sectional view of the lens device of FIG. 6.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Stepping motor 10 Rotor 20 Stator 30,40,50,60 Magnetic pole piece 31,41,51,61 Magnetic pole 35,55 Yoke piece 37,57 Coil

Claims (6)

A rotor made of a permanent magnet, and a stator for rotating the rotor,
The stator includes magnetic poles arranged on the outer periphery of the rotor at a predetermined angle in the circumferential direction with a space between the rotor and facing each other with the inner ends facing each other across the rotor. Two pairs of magnetic pole pieces, two yoke pieces formed by connecting the outer ends of the two pairs of magnetic pole pieces, and the two yoke pieces are wound around each of the two pieces. A stepping motor constituted by two coils,
A stepping motor characterized in that the two coils extend in a direction perpendicular to the rotation axis direction of the rotor and are arranged at positions overlapping each other.   One yoke piece is disposed on one side in the rotation axis direction of the rotor, and the other yoke piece is disposed on the other side in the rotation axis direction of the rotor, with the pair of magnetic pole pieces interposed therebetween. The stepping motor according to claim 1, wherein the stepping motor is arranged.   The stepping motor according to claim 1, wherein the magnetic pole pieces adjacent to each other are connected and integrated with each other by a thin portion.   The concave portion or the convex portion opposed to each other across the rotor is provided on the inner circumference of the plurality of magnetic pole pieces opposed to the outer circumference in the radial direction of the rotor. The stepping motor according to claim 1.   One pole piece of the pair of pole pieces is arranged on the same axis as the axis of the different pole piece of the pole piece, and another axis of the different set is placed on an axis parallel to the axis. The stepping motor according to any one of claims 1 to 4, wherein a magnetic pole piece and another magnetic pole piece that forms a pair with the magnetic pole piece are arranged. A lens device comprising the stepping motor according to claim 5,
A lens provided adjacent to the stepping motor;
A lens apparatus comprising: an advancing / retracting mechanism that engages with the rotating shaft of the rotor and engages the lens with the other end to move the lens back and forth.

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