Stepping motor

Abstract

Even when multiple coils are present, this prevents the coils from diverging from the stator. [Solution] The stepping motor 100 includes a rotor 3 magnetized in the radial direction, a stator 1 having a straight section 12, a first protruding section 13 and a second protruding section 14 provided on both ends of the straight section 12 in the longitudinal direction and extending in a direction intersecting the longitudinal direction of the straight section 12, and a rotor receiving section 20 for receiving the rotor 3 provided on the second protruding section 14, two yokes 5 arranged on both sides of the straight section 12 along the longitudinal direction L of the straight section 12, with one end of each yoke 5 being locked to the first protruding section 13 via a first support member 150 and the other end being locked to the second protruding section 14 via a second support member 180, and a plurality of coils provided magnetically coupled to the stator 1, wherein a retractable section 65 is formed on one end of the yoke 5 so as to wrap around from the yoke 5 side of the first support member 150 to the straight section 12 side.

Description

Technical Field

[0001] The present invention relates to a stepping motor.

Background Art

[0002] Conventionally, a stepping motor having a rotor, a stator, and a plurality of coils has been known (see, for example, the "two-coil type stepping motor" shown in Patent Document 1).

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] However, when a plurality of coils are provided, there is a risk that the coils may deviate from the stator.

[0005] The present invention has been made in view of the above circumstances, and an object thereof is to provide a stepping motor capable of preventing the deviation of coils from the stator even when a plurality of coils are provided.

Means for Solving the Problems

[0006] To solve the aforementioned problems, the stepping motor according to the present invention comprises a rotor magnetized in the radial direction, a stator having a straight portion, a first and second protruding portion provided on both ends of the straight portion in the longitudinal direction and extending in a direction intersecting the longitudinal direction of the straight portion, with a rotor receiving portion for receiving the rotor provided on the second protruding portion, two yokes arranged on both sides of the straight portion along the longitudinal direction of the straight portion, one end of which is locked to the first protruding portion via a first support member and the other end of which is locked to the second protruding portion via a second support member, and a plurality of coils provided magnetically coupled to the stator, wherein a retraction portion is formed on one end of the yoke so as to wrap around from the yoke side of the first support member to the straight portion side. [Effects of the Invention]

[0007] According to the present invention, even when multiple coils are provided, it is possible to prevent the coils from separating from the stator. [Brief explanation of the drawing]

[0008] [Figure 1] (a) is a plan view of the stepping motor according to the embodiment, (b) is a cross-sectional view of the main part of the stepping motor along line bb in (a), and (c) is a diagram of the main components of the main circuit board shown in (b). [Figure 2] This is a perspective view of a stepping motor according to an embodiment. [Figure 3] Figure 2 is a perspective view of the coil substrate and surrounding area of ​​the stepping motor shown. [Figure 4] (a) is a plan view of the stator, (b) is a side view of the stator as seen from arrow b in (a), (c) is a plan view of the stator with the coil and coil substrate mounted, (d) is a front view of the stator as seen from arrow d in (c), and (e) is a plan view of the coil substrate. [Figure 5](a) is a plan view of the first and second side yokes, (b) is a cross-sectional view of the main part of the second side yoke along line bb in (a), (c) is a plan view of the first and second side yokes with the coil and coil substrate mounted on them, (d) is a front view of the first and second side yokes as seen from the direction of arrow d in (c), and (e) is a plan view of the coil substrate. [Figure 6] This is a plan view illustrating the curved section formed in the yoke. [Modes for carrying out the invention]

[0009] An embodiment of the stepping motor according to the present invention will be described with reference to Figures 1 to 6. The stepping motor according to this embodiment is a small motor that is used to drive a hand movement mechanism or date mechanism for time display devices such as wristwatches. Although the embodiments described below are subject to various technically preferred limitations for carrying out the present invention, the scope of the present invention is not limited to the following embodiments and illustrated examples.

[0010] As shown in Figure 1(a), the stepping motor 100 comprises a stator 1, a rotor 3, two yokes 5 (a first side yoke 51 and a second side yoke 52, described later), and three coils (a first coil C1, a second coil C2, and a third coil C3) that are magnetically coupled to the stator 1. As will be described later, in this embodiment, of the three coils, the first coil C1 is a stator-integrated coil formed on the straight portion 12 of the stator 1. The second coil C2 and the third coil C3 are formed on the yokes 5 (a first side yoke 51 and a second side yoke 52) that are locked to the stator 1, respectively. Thus, the stepping motor 100 according to this embodiment is a triple-coil motor equipped with three coils.

[0011] The rotor 3 is a magnet that is magnetized with two poles in the radial direction. For example, Figure 1(a) shows that the poles are different in the white-out area and the area with hatched lines on the rotor 3. The boundary between the S pole and the N pole is called the "polarization position". In this embodiment, the rotor 3 is formed in a substantially disc shape, and a rotating support shaft (not shown) is attached to the center of the rotor 3. As the magnet applied to the rotor 3, a permanent magnet such as a rare earth magnet (e.g., a samarium-cobalt magnet) is preferably used, but the type of magnet that can be applied to the rotor 3 is not limited to this. The rotor 3 is received in the rotor receiving portion 20 of the stator 1, which will be described later, and is arranged to be rotatable around the rotating support shaft as the center of rotation. In this embodiment, the rotor 3 is able to rotate within the rotor receiving section 20 in both the forward direction (i.e., clockwise direction) and the reverse direction (i.e., counterclockwise direction) at a predetermined step angle (60 degrees in this embodiment) by sequentially applying drive pulses to any one of the three coils (first coil C1, second coil C2, and third coil C3) described later. Gears, etc. (not shown) that constitute a gear train mechanism for moving the hands of a time display device (e.g., a watch) such as a wristwatch are connected to the rotation pivot shaft, and the rotation of the rotor 3 causes these gears, etc. to rotate. The rotor provided in the stepping motor 100 is not limited to a magnet magnetized with two poles in the radial direction. For example, a magnet with more than two poles, such as a six-pole magnet, may be used.

[0012] In this embodiment, the stator 1 comprises a straight section 12 and a first protrusion 13 and a second protrusion 14 provided at both ends of the straight section 12 in the longitudinal direction L. Figures 4(a) and 4(b) illustrate the case where the first protrusion 13 is provided at the right end of the straight section 12 and the second protrusion 14 is provided at the left end of the straight section 12. The first protrusion 13 and the second protrusion 14 protrude in a direction intersecting the longitudinal direction L of the straight section 12. In this embodiment, the "direction intersecting the longitudinal direction L of the straight section 12" is a direction perpendicular to the longitudinal direction L. The direction of protrusion of the first protrusion 13 and the second protrusion 14 is the width direction W in Figure 1(a), etc. The first protruding portion 13 and the second protruding portion 14 protrude from both ends of the straight portion 12 to the left and right in the width direction W (up and down in Figure 4(a)) by approximately the same length, and as shown in Figure 4(a), the stator 1 in this embodiment is generally H-shaped overall.

[0013] The stator 1 is formed from a high-permeability material such as permalloy. The straight portion 12 constitutes the center yoke in the stepping motor 100. In this embodiment, as shown in Figure 4(b), the straight portion 12 is taller in the thickness direction than the first protruding portion 13 and the second protruding portion 14 when viewed from the side, and coil frames 8 of the coil case are installed between the straight portion 12 and the first protruding portion 13, and between the straight portion 12 and the second protruding portion 14, respectively (see Figures 1(b), 2 and 4(c)). A first coil C1 is formed in the straight portion 12 by winding wire between these two coil frames 8. As shown in Figures 4(a) and 4(c), two screw holes 131 are formed at substantially symmetrical positions in the width direction W of the first protruding portion 13. A support post 15 for screw fastening, described later, is inserted through each screw hole 131 from one side (the lower side in Figure 1(b)), and a screw 16 is inserted through the support post 15 from the other side (the upper side in Figure 1(b)). In this embodiment, the support post 15 and the screw 16 constitute the first support member 150. As shown in Figure 1(b), the first support member 150 is inserted approximately perpendicular to the main surface of the first protruding portion 13.

[0014] Furthermore, a first coil substrate 17 (see Figures 1(a), 4(c), and 4(e)) is positioned on the first protruding portion 13, on the side of the straight portion 12, and is formed in a substantially triangular shape to avoid the two screw holes 131. The first coil substrate 17 is provided with a pair of connection points 171 to which the wire ends 11 of the first coil C1 are connected. In this embodiment, as shown in Figures 1(a) and 2, three coil substrates 17 (the first coil substrate 17a and the second coil substrate 17b and third coil substrate 17c, described later) corresponding to the three coils (the first coil C1, the second coil C2, and the third coil C3) are positioned on the first protruding portion 13. Each coil substrate 17 is positioned on the first protruding portion 13 via a height-adjusting spacer S, so that the upper surfaces of all three coil substrates 17 are substantially flush. This allows all three coil boards 17 to be electrically connected to the main board 7 when the main board 7, described later, is placed on top of the coil board 17.

[0015] Furthermore, there is a risk of wire breakage if the wire end 11 comes into contact with the end face of the coil substrate 17 (first coil substrate 17a, second coil substrate 17b, third coil substrate 17c). For this reason, in this embodiment, the coil frame 8 of the coil case is provided to the same height as the upper surface of the coil substrate 17 (first coil substrate 17a, second coil substrate 17b, third coil substrate 17c), and the wire end 11 is connected to the connection point 171 of the coil substrate 17 from above in a curved shape so as to go over the coil frame 8. Although Figure 2 illustrates the case where the second coil C2 is connected to the connection point 171 of the second coil substrate 17 as an example, this configuration is common when three coils (first coil C1, second coil C2, third coil C3) are connected to the connection point 171 of each coil substrate (first coil substrate 17, second coil substrate 17, third coil substrate 17). This prevents wire breakage. Furthermore, in this embodiment, a wire bonding section 110 (see Figure 3) is provided that covers the wire end 11 connected to the connection point 171 with a resin bonding material, thereby providing more reliable protection for the wire end 11 (see Figure 3).

[0016] Furthermore, as shown in Figures 4(a) and 4(c), two screw holes 141 are formed at substantially symmetrical positions in the width direction W of the second protruding portion 14. A support column 18 for screw fastening, described later, is inserted through each screw hole 141 from one side (the lower side in Figure 1(b)), and a screw 19 is inserted through the support column 18 from the other side (the upper side in Figure 1(b)). In this embodiment, the support column 18 and the screw 19 constitute the second support member 180. As shown in Figure 2, the second support member 180 is inserted substantially perpendicular to the main surface of the second protruding portion 14.

[0017] At approximately the center of the second protruding portion 14 in the width direction W, and at the intersection of the straight portion 12 of the stator 1, the first side yoke 51 and the second side yoke 52 (described later), a rotor receiving portion 20 is formed, which is a substantially circular hole that receives the rotor 3. In this embodiment, the rotor receiving portion 20 has recesses 21 (notches) that open toward the rotor 3, arranged at approximately equal intervals along the outer circumference of the rotor 3. The recesses 21 maintain the rotor 3 in a stationary state, and in this embodiment, six recesses 21 are formed on the inner circumferential surface of the rotor receiving portion 20 of the stator 1. The index torque (holding torque) of the rotor 3 is greatest when one of the recesses 21 and the polarization position of the rotor 3 are facing each other. For this reason, in a non-energized state where no drive pulse is applied, the rotor 3 remains stationary at a position where one of the recesses 21 and the polarization position of the rotor 3 are facing each other, as shown in Figure 1(a).

[0018] Also, on the side of the second overhanging portion 14 facing the first overhanging portion 13 (the side proximal to the first overhanging portion 13), a first notch portion 142 is provided at a position corresponding to between two of the recesses 21 located on the end side in the width direction W among the recesses 21 provided in the rotor receiving portion 20. The first notch portions 142 are provided on both sides sandwiching the rotor 3 (the rotor receiving portion 20 for receiving the rotor 3), and each first notch portion 142 is formed so as to bite into between the two recesses 21. Further, on the side of the end portion of the stator 1 in the longitudinal direction L, that is, on the side distal to the first overhanging portion 13 substantially parallel to the side of the second overhanging portion 14 where the first notch portion 142 is provided in the embodiment, a second notch portion 143 is formed. The second notch portion 143 is formed at a position corresponding to between two of the recesses 21 provided on the end portion side in the longitudinal direction L so as to bite into between the two recesses 21.

[0019] The first notch portion 142 and the second notch portion 143 are arranged so as to surround the rotor 3 from three directions, and the shape of the periphery of the rotor receiving portion 20 of the rotor 3 surrounded by the first notch portion 142 and the second notch portion 143 is substantially an equilateral triangle. At the locations where the first notch portion 142 and the second notch portion 143 are provided, the width from the edge of the rotor receiving portion 20 to the outer edge portion of the second overhanging portion 14 becomes narrow. In such a narrow portion, magnetic saturation is likely to occur and the magnetic resistance becomes large compared to other portions, so the passage of magnetic flux is hindered. Thereby, in the embodiment, the first notch portion 142 and the second notch portion 143 function as magnetic flux regulating portions that regulate the direction of magnetic flux so that the magnetic flux from the rotor 3 is directed at approximately 120-degree intervals.

[0020] In an embodiment, the two yokes 5 (the first side yoke 51 and the second side yoke 52) provided in the stepping motor 100 are arranged along the longitudinal direction L of the straight portion 12 on both sides of the straight portion 12 as shown in FIGS. 1(a) and 2. The first side yoke 51 and the second side yoke 52 have a shape that is substantially reversed left and right (up and down in FIG. 1(a)) with the straight portion 12 as the center, and since their basic configurations are the same, when not particularly distinguished, they are simply referred to as the yoke 5. In the embodiment, the yoke 5 is formed of a high magnetic permeability material such as permalloy. The two yokes 5 each include a straight portion 61, an overhanging portion 62 arranged on one end side of the straight portion 61 and wider than the straight portion 61, and an overhanging portion 63 arranged on the other end side of the straight portion 61 and wider than the overhanging portion 62.

[0021] Between the straight portion 61 and the overhanging portion 62 and between the straight portion 61 and the overhanging portion 63 in each yoke 5, coil frames 8 of the coil case are installed respectively (see FIG. 2). As shown in FIG. 2, a second coil C2 is formed by winding a wire between a pair of coil frames 8 on the straight portion 61 of the first side yoke 51 arranged on the left side (upper side in FIGS. 1(a) and FIGS. 5(a), etc.) of the straight portion 12 of the stator 1. Similarly, for the second side yoke 52 arranged on the right side (lower side in FIGS. 1(a) and FIGS. 5(a), etc.) of the straight portion 12 of the stator 1, a third coil C3 is formed on the straight portion 61 by winding a wire between a pair of coil frames 8 installed on the straight portion 61. One end side of each of the two yokes 5 is locked to the first overhanging portion 13 via the first support member 150 (see FIGS. 1(a) and 1(b)), and the other end side is locked to the second overhanging portion 14 via the second support member 180 (see FIGS. 1(a) and 1(b)).

[0022] In this embodiment, the protruding portion 63 of the first side yoke 51 is locked to one side (upper side in Figure 1(a)) of the second protruding portion 14 of the stator 1 in the width direction W via a second support member 180. Similarly, the protruding portion 63 of the second side yoke 52 is locked to the other side (lower side in Figure 1(a)) of the second protruding portion 14 of the stator 1 in the width direction W via a second support member 180. Specifically, the protruding portion 63 of the yoke 5 is provided with a screw hole 631, and the position of the screw hole 631 corresponds to the position of a screw hole 141 formed in the second protruding portion 14 of the stator 1. A support column 18 is inserted through the screw holes 141 and 631, and screws 19 are fastened to the support column 18, thereby locking the protruding portion 63 of the yoke 5 to the second protruding portion 14. Furthermore, the protruding portion 62 of the first side yoke 51 is locked to one side (upper side in Figure 1(a)) of the first protruding portion 13 of the stator 1 in the width direction W via the first support member 150. Similarly, the protruding portion 62 of the second side yoke 51 is locked to the other side (lower side in Figure 1(a)) of the first protruding portion 13 of the stator 1 in the width direction W via the first support member 150. Specifically, the protruding portion 62 of the yoke 5 has a roughly C-shaped notch 621 formed at a position corresponding to the screw hole 131 formed in the first protruding portion 13 of the stator 1. The support column 18 is inserted through the screw hole 131 and the notch 621, and screws 16 are fastened to the support column 15, thereby locking the protruding portion 62 to the first protruding portion 13.

[0023] As shown in Figure 5(a), etc., a wrap-around portion 65 is formed on one end of the yoke 5, which wraps around from the yoke side of the first support member 150 to the straight portion 12 side. In this embodiment, the wrap-around portion 65 is formed on the free end side of the notch 621 provided in the protruding portion 62. The wrap-around portion 65 will now be described in detail with reference to Figure 6. Note that Figure 6 illustrates the second side yoke 52 which is positioned below the straight portion 12 of the stator 1 in Figure 1(a), etc., but the same applies to the first side yoke 51. In Figure 6, the straight portion 12 of the stator 1 is virtually shown by a dashed line.

[0024] As shown in Figures 1(a) and 6, the first support member 150 in the embodiment is cylindrical with a roughly circular shape when viewed from above (in Figure 6, the center of the circle of the first support member 150 is denoted as center point P1). The retractable portion 65 is locked to the outer circumferential surface of the first support member 150 on the side of the straight portion 12, thereby restricting its movement in the direction away from the straight portion 12 (the direction of separation α indicated by the arrow in Figure 6). That is, in the embodiment, the second support member 180, which locks the protruding portion 63 to the second protruding portion 14, is also cylindrical with a roughly circular shape when viewed from above (in Figure 6, the center of the circle of the second support member 180 is denoted as point P2). Therefore, when the yoke 5 is locked to the stator 1 via the second support member 180, it is in a state in which it can rotate in the direction away from the straight portion 12 of the stator 1 (direction of separation α) with the center point P2 of the circle of the second support member 180 as the center of rotation. In this regard, the rotating portion 65 is provided so as to wrap around the straight portion 12 side of the first support member 150, which prevents the yoke 5 from rotating in the direction of separation α with the center point P2 as the center of rotation. In particular, in this embodiment, the rotating portion 65 is formed in a hook shape. As a result, the rotating portion 65 reliably catches on the first support member 150, and the rotation of the yoke 5 in the direction of separation α is more reliably restricted.

[0025] The wrap-around portion 65 does not need to wrap around the outer circumference of the first support member 150 as deeply as illustrated in Figures 6 and 5(a), etc. For example, as shown in Figure 6, if a straight line is drawn connecting the center point P1 of the first support member 150 and the center point P2 of the second support member 180 in a plan view, and a perpendicular line is drawn perpendicular to this line and tangent to the distal outer surface of the first support member 150 relative to the second support member 180, it is preferable that the wrap-around portion 65 is provided extending beyond the perpendicular line toward the second support member 180. In other words, for example, the wrap-around portion 65 may be provided extending within a fan-shaped region along the outer surface of the straight portion 12 on the first support member 150. The wrap-around portion 65 only needs to be able to prevent the yoke 5 from rotating with the center point P2 as the center of rotation, and the range, shape, and size of the wrap-around portion 65 can be appropriately determined depending on the radial size and shape of the first support member 150, etc.

[0026] A coil base plate 17 is placed on the protruding portion 62 of each yoke 5, to which the wire ends 11 of the coils are connected. Specifically, the protruding portion 62 of the first side yoke 51 is fitted with a second coil base plate 17b corresponding to the second coil C2, and the protruding portion 62 of the second side yoke 52 is fitted with a third coil base plate 17c corresponding to the third coil C3. Also, similar to the case of the first coil C1 provided on the straight portion 12 of the stator 1, each coil base plate 17 (the second coil base plate 17b and the third coil base plate 17c) is placed on the protruding portion 62 via a spacer S (see Figures 2 and 3). As a result, the height positions of the three coil base plates 17 corresponding to the three coils are aligned almost flush, as shown in Figures 2 and 3.

[0027] Next, the operation of the stepping motor 100 of this embodiment will be described. When assembling the stepping motor 100 according to this embodiment, a coil frame 8 is attached to the straight portion 12 of the stator 1 as shown in Figure 4(a), and windings are made almost uniformly between the coil frame 8. In this way, the straight portion 12 is used as the center yoke to form the first coil C1. A first coil substrate 17a is placed on the first protruding portion 13 of the stator 1 via a spacer S, and the wire end 11 drawn from the first coil C1 is connected to the connection point 171 provided on the first coil substrate 17a, and a wire bonding portion 110 is formed from resin over the connection portion. In this way, the connection portion of the wire end 11 to the coil substrate 17 is covered and protected by resin.

[0028] Furthermore, a coil frame 8 is attached to the straight portion 61 of the first side yoke 51, and windings are made almost uniformly between the coil frames 8. This forms a second coil C2 on the straight portion 61. A second coil substrate 17b is placed on the protruding portion 62 of the first side yoke 51 via a spacer S, and the wire end 11 drawn from the second coil C2 is connected to a connection point 171 provided on the second coil substrate 17b, and a wire bonding portion 110 is formed from resin over the connection portion. This covers and protects the connection portion of the wire end 11 to the coil substrate 17 with resin. Similarly, windings are made almost uniformly on the straight portion 61 of the second side yoke 52, and a third coil C3 is formed on the straight portion 61. A third coil substrate 17c is positioned on the protruding portion 62 of the second side yoke 52 via a spacer S. The wire ends 11 drawn from the third coil C3 are connected to the connection points 171 provided on the third coil substrate 17c, and a wire bonding portion 110 is formed from resin over the connection portion. As a result, the three coil substrates 17, each connected to the wires of the three coils, are positioned on the first protruding portion 13 of the stator 1 with their surface heights almost flush (see Figure 3).

[0029] In this state, the main board 7 is placed on the first protruding portion 13 from above the coil board 17, and the coil board 17 and the main board 7 are connected electrically. As shown in Figures 2 and 3, each coil board 17 is provided with terminal portions 172 for electrical connection with the main board 7 at locations different from the connection points 171 to which the wire ends 11 are connected. The terminal portions 172 are provided at two locations on the first coil board 17a (terminal portions 172a and 172b in Figures 2 and 3), at two locations on the second coil board 17b (terminal portions 172c and 172d in Figures 2 and 3), and at two locations on the third coil board 17c (terminal portions 172e and 172f in Figures 2 and 3). As shown in Figure 1(c), conductive pad portions 72 are arranged on the main board 7 at positions corresponding to each of these terminal portions 172. In Figure 1(c), the main board 7 is shown inverted, with the side that contacts the coil board 17 facing outwards. Specifically, in Figure 1(c), pad portion 72a is connected to terminal portion 172a of the first coil board 17a, and pad portion 72b is connected to terminal portion 172b. Pad portion 72c is connected to terminal portion 172c of the second coil board 17b, and pad portion 72d is connected to terminal portion 172d. Pad portion 72e is connected to terminal portion 172e of the second coil board 17c, and pad portion 72f is connected to terminal portion 172f.

[0030] Each terminal portion 172 and the corresponding pad portion 72 on the main board 7 are arranged to surround the first support member 150. That is, as shown in Figure 1(c), the main board 7 has through holes 71 formed at positions corresponding to the first support member 150 during installation, through which the first support member 150 is inserted. Each terminal portion 172 and the corresponding pad portion 72 on the main board 7 are arranged to divide the area around the first support member 150 by approximately 120 degrees each. As a result, six conductive areas, two for each of the three coils, can be stably secured around the first support member 150. The coil board 17 and the main board 7 are then fastened together at the first support member 150 by screw fastening with screws 16 on the first support member 150. By arranging the conductive areas between the coil board 17 and the main board 7 close to the screw fastening points in this way, a stable connection can be achieved.

[0031] This allows the three coils to be stably fixed around the first support member 150 and assembled to the stator 1, resulting in a stepping motor 100 that is effective and efficient in terms of area, structure, and electricity. In addition, the main board 7 has openings 73 formed at positions corresponding to the wire bonding portions 110 formed on the coil board 17 side, thus avoiding the wire bonding portions 110. As a result, even if the wire bonding portions 110 are formed as raised areas on the surface of the coil board 17, the terminal portions 172 on the coil board 17 side and the pad portions 72 on the main board side make surface contact without rattling, achieving stable conductivity. Furthermore, by concentrating the conductive portions between the boards around the first support member 150, it is easy to arrange the conductive portions while avoiding the wire bonding portions 110, thus making the mounting area compact.

[0032] Furthermore, each yoke 5 is provided with a retractable portion 65 at the end of the protruding portion 62 that wraps around to the straight portion 12 side of the first support member 150. This prevents the yoke 5 from separating from the straight portion 12 (the separating direction α, which is the direction in which the stepping motor 100 spreads outwards). As a result, even if the stepping motor 100 has multiple coils, the multiple coils will not separate from the stator 1. In addition, the stepping motor 100 can be compactly mounted on the circuit board of various devices, and can reliably ensure electrical contact with the main circuit board 7.

[0033] As described above, according to this embodiment, the stepping motor 100 includes a rotor 3 magnetized in the radial direction, a stator 1 having a straight section 12, a first protruding section 13 and a second protruding section 14 provided on both ends of the straight section 12 in the longitudinal direction and extending in a direction intersecting the longitudinal direction of the straight section 12, and a rotor receiving section 20 for receiving the rotor 3 provided on the second protruding section 14, two yokes 5 arranged on both sides of the straight section 12 along the longitudinal direction L of the straight section 12, with one end of each yoke 5 locked to the first protruding section 13 via a first support member 150 and the other end of each yoke 5 locked to the second protruding section 14 via a second support member 180, and a plurality (three in this embodiment) of coils provided magnetically coupled to the stator 1, wherein a retractable section 65 is formed on one end of the yoke 5 so as to wrap around from the yoke 5 side of the first support member 150 to the straight section 12 side. As a result, even when the stepping motor 100 has multiple coils (three coils in this embodiment), the rotation portion 65 is locked to the first support member 150, preventing the multiple coils from separating from the stator 1. Therefore, there is no need to provide walls or the like to prevent the coils from separating, and the stepping motor 100 can be compactly mounted on the circuit board of various devices, thereby increasing the mounting density.

[0034] Furthermore, in this embodiment, the first support member 150 is inserted substantially perpendicularly to the main surface of the first protruding portion 13, and the second support member 180 is inserted substantially perpendicularly to the main surface of the second protruding portion 14. This allows the stator 1, each yoke 5, and the main board 7 to be easily fastened together in the vertical direction. This results in good assembly, a compact and stable connection.

[0035] Furthermore, the rotating portion 65 in this embodiment is formed in a hook shape. Therefore, separation of the yoke 5 from the stator 1 can be effectively prevented with a simple configuration.

[0036] Furthermore, the first support member 150 in this embodiment is cylindrical, and the rotating portion 65 is locked to the outer circumferential surface of the first support member 150 on the side of the straight portion 12, thereby restricting its movement in the direction away from the straight portion 12 (separation direction α). This ensures that the yoke 5 does not detach from the stator 1.

[0037] Furthermore, the retractable portion 65 in this embodiment is provided so as to extend beyond the perpendicular line drawn perpendicular to the line connecting the center (center point P1) of the first support member 150 and the center (center point P2) of the second support member 180 in a plan view, and tangent to the distal outer surface of the first support member 150 relative to the second support member 180, when such a perpendicular line is drawn. This ensures that the yoke 5 does not separate from the stator 1.

[0038] Furthermore, the retractable portion 65 in this embodiment is provided extending outwards within a fan-shaped region along the outer circumferential surface of the straight portion 12 side of the first support member 150. The yoke 5 can rotate in a direction away from the stator 1 with the center point P2 as the center of rotation, but the rotation of the yoke 5 is restricted by the provision of the retractable portion 65 in the fan-shaped region along the outer circumferential surface of the straight portion 12 side. Therefore, separation of the yoke 5 from the stator 1 can be reliably prevented.

[0039] Furthermore, in this embodiment, of the three coils, the first coil C1 is formed on the straight section 12, the second coil C2 and the third coil C3 are each formed on the yoke 5, and coil substrates 17 corresponding to the three coils are arranged on the first protruding section 13. Therefore, by arranging and connecting the main substrate 7, which has conductive pad sections 72, corresponding to the first protruding section 13, electrical conductivity can be achieved with all three coils.

[0040] Furthermore, in this embodiment, the coil substrates 17 corresponding to the three coils are arranged so that they each divide the area on the first protruding portion 13 by approximately 120 degrees when viewed from above. This allows for a stable conductive structure between the main substrate and each coil, and enables a stable supply of drive pulses to any of the coils via the main substrate 7.

[0041] Although embodiments of the present invention have been described above, it goes without saying that the present invention is not limited to these embodiments and can be modified in various ways without departing from its essence. For example, in the above embodiment, the case in which the retractable portion 65 is hook-shaped was illustrated, but the shape of the retractable portion is not limited to this. The retractable portion 65 only needs to be able to restrict the rotation of the yoke 5 with the center point P2 as the center of rotation, and for example, it may have less protrusion toward the first support member 150 than in the illustrated example. Also, the protruding portion 62 may have a screw hole through which the first support member 150 is inserted instead of the substantially C-shaped notch 621, in which case the material around the screw hole functions as a retractable portion that wraps around to the straight portion 12 side of the first support member 150.

[0042] Furthermore, although the embodiment illustrates a case where the stepping motor 100 is provided with three coils that are magnetically coupled to the stator 1, there may be multiple coils, and it is not limited to three. For example, the present invention can also be applied to a configuration in which the first coil C1 formed on the straight portion 12 is not included among the three coils shown in the embodiment.

[0043] Furthermore, while the embodiment illustrates the case where the stepping motor 100 is used in a clock or the like, the devices to which the stepping motor 100 can be applied are not limited to this.

[0044] Although several embodiments of the present invention have been described above, the scope of the present invention is not limited to the embodiments described above, but includes the scope of the invention as described in the claims and its equivalents. [Explanation of Symbols]

[0045] 1... Stator, 3... Rotor, 5... Yoke, 12... Straight section, 13... First extension section, 14... Second extension section, 20... Rotor receiving section, 65... Rotation section, 100... Stepping motor, 150... First support member, 180... Second support member, C1... First coil, C2... Second coil, C3... Third coil

Claims

1. A rotor magnetized in the radial direction, A stator having a straight section and a first and second protruding sections provided on both ends of the straight section in the longitudinal direction, respectively, and extending in a direction intersecting the longitudinal direction of the straight section, wherein a rotor receiving section for receiving the rotor is provided on the second protruding section, Two yokes are arranged on both sides of the straight section, along the longitudinal direction of the straight section, with one end of each yoke being secured to the first protruding section via a first support member and the other end of each yoke being secured to the second protruding section via a second support member. The stator comprises a plurality of coils that are magnetically coupled to the stator, A rotating portion is formed on one end of the yoke, which wraps around from the yoke side to the straight portion side of the first support member. Stepping motor.

2. The first support member is inserted substantially perpendicularly to the main surface of the first protruding portion, and the second support member is inserted substantially perpendicularly to the main surface of the second protruding portion. The stepping motor according to claim 1.

3. The aforementioned retractable portion is formed in a hook shape. The stepping motor according to claim 1.

4. The first support member is cylindrical, and the retractable portion is locked to the outer circumferential surface of the first support member on the side of the straight portion, thereby restricting its movement in the direction away from the straight portion. The stepping motor according to claim 1.

5. The aforementioned retractable portion is provided so as to extend beyond the perpendicular line drawn perpendicular to the line connecting the center of the first support member and the center of the second support member in a plan view, and tangent to the distal outer surface of the first support member relative to the second support member. The stepping motor according to claim 1.

6. The aforementioned retractable portion is provided extending outwards within a fan-shaped region along the outer circumferential surface of the straight portion side of the first support member. The stepping motor according to claim 1.

7. The plurality of coils comprises three coils, of which the first coil is formed in the straight section, and the second and third coils are each formed in the yoke. The first protruding portion is arranged with coil substrates corresponding to the three coils. The stepping motor according to claim 1.

8. The coil substrates corresponding to the three coils are arranged so that the region on the first protruding portion is divided by approximately 120 degrees when viewed from above. The stepping motor according to claim 7.

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