Stepping motor and timepiece

Abstract

The invention provides a stepping motor and a timepiece which enable a rotor to be static at a specified position with a minimum installation space and high precision. A stepping motor (100) is provided with: a rotor (3) magnetized in the radial direction; a stator (1) having a linear portion (12) extending in a longitudinal direction (L), which is a first direction, a second protruding portion (14) provided on at least one end side of the linear portion and protruding in a direction intersecting the longitudinal direction in which the linear portion extends, and a rotor housing portion (20) provided on the second protruding portion and housing the rotor; two yokes (5) respectively arranged on both sides of the linear portion along the longitudinal direction of the linear portion; and a plurality of coils provided so as to be magnetically coupled to the stator, in which first cutout portions (142) provided on both sides of the rotor at least and second cutout portions (145) extending further toward the end of the stator in the first direction than the first cutout portions are formed on the extension portions.

Description

TECHNICAL FIELD

[0001] The present disclosure relates to a stepping motor and a timepiece. BACKGROUND

[0002] A stepping motor has a step angle that is sought depending on the use. For example, in a case where a stepping motor is used as a motor for causing a hand of a timepiece to move, it is necessary to act with a prescribed step. In this regard, it is known in the past that, in a two-coil type stepping motor, one magnetic flux saturation portion and two recesses (slit portions in Patent Document 1) are provided in a stator (see Japanese Patent Application Publication No. 2016-152636). SUMMARY

[0003] PROBLEMS TO BE SOLVED BY THE INVENTION

[0004] However, in a case of a three-coil motor having three coils, for example, if the rotor is to be rotated intermittently at prescribed intervals with a prescribed step and so on to cause a timepiece to move, when the magnetic poles of the rotor are oriented toward the central yoke, the magnetic poles are stably at rest, but if the magnetic poles are to be oriented toward the second and third yokes on both sides to be at rest, the distribution of the index torque tends to become unstable, and sometimes it is difficult to make the magnetic poles at rest at prescribed positions. It is considered that the main reason is that the magnetic flux is to be returned in the shortest path.

[0005] The present disclosure was completed in view of the circumstances as described above, and aims to provide a three-coil stepping motor and a timepiece capable of making a rotor at rest at a prescribed position with a minimum installation space with high accuracy.

[0006] MEANS FOR SOLVING THE PROBLEMS

[0007] In order to solve the problems, the stepping motor of the present disclosure is characterized by comprising: a rotor magnetized in a radial direction; a stator having a straight portion extending in a first direction, a protruding portion provided on at least one end side of the straight portion and protruding in a direction intersecting the extending direction of the straight portion, and a rotor housing portion provided in the protruding portion and housing the rotor; two yokes respectively arranged on both sides of the straight portion along the length direction of the straight portion; and a plurality of coils provided in magnetic coupling with the stator, a first notch portion is provided on both sides at least through the rotor, and a second notch portion extends toward the end portion side of the first direction of the stator more than the first notch portion.

[0008] EFFECT OF THE INVENTION

[0009] According to the present disclosure, the effect of being able to make a rotor at rest at a prescribed position with a minimum installation space with high accuracy is achieved. BRIEF DESCRIPTION OF DRAWINGS

[0010] Figure 1 This is a plan view of the stepper motor in the implementation method.

[0011] Figure 2 This is a perspective view of the stepper motor in the implementation method.

[0012] Figure 3 It is along Figure 1 A cross-sectional view of the main parts of the stepper motor on line III-III.

[0013] Figure 4A This is a plan view of the stator.

[0014] Figure 4B From Figure 4A The side view of the stator viewed in the direction of arrow b.

[0015] Figure 4C This is a plan view showing the stator with coils and a coil substrate mounted on it.

[0016] Figure 4D From Figure 4C The front view of the stator is viewed in the direction of arrow d.

[0017] Figure 5A This is a plan view of the first and second lateral yokes.

[0018] Figure 5B This is a plan view showing the state in which coils and coil substrates are mounted on the first and second side yokes.

[0019] Figure 5C From Figure 5B The front view of the first and second lateral yokes as observed in the direction of arrow d.

[0020] Figure 6 It is a plan view used to illustrate the second notch formed in the second protrusion of the embodiment and the flow of magnetic flux from the rotor.

[0021] Figure 7 It is a plan view used to illustrate the notch formed in the conventional second protrusion and the flow of magnetic flux from the rotor. Detailed Implementation

[0022] Reference Figures 1 to 7 This paper describes one embodiment of the stepper motor disclosed herein. The stepper motor of this embodiment is, for example, a small motor used to drive a hand-running mechanism, date mechanism, or similar device that moves the hands of a time display device such as a watch. Furthermore, in the embodiments described below, various technically preferred limitations have been added for the purpose of implementing this disclosure, but the scope of this disclosure is not limited to the following embodiments and illustrated examples.

[0023] like Figure 1 andFigure 2 As shown, the stepper motor 100 includes a stator 1, a rotor 3, two magnetic yokes 5 (the first yoke 51 and the second yoke 52 described later), and three coils (the first coil C1, the second coil C2, and the third coil C3) magnetically coupled to the stator 1. As described later, in this embodiment, 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 respectively formed on the magnetic yokes 5 (the first yoke 51 and the second yoke 52) that are engaged with the stator 1. Thus, the stepper motor 100 of this embodiment is a three-coil motor with three coils.

[0024] Rotor 3 is a magnet that is radially bipolar magnetized. For example, in Figure 1 The blank portion and the portion shaded with diagonal lines in the rotor 3 are shown, and they are extremely different. Furthermore, the boundary between the S pole and the N pole is designated as the "polarization position". In this embodiment, the rotor 3 is formed in a generally disk-shaped manner, and a rotation support shaft (not shown) is mounted at the center of the rotor 3. As the magnet used in the rotor 3, a permanent magnet such as a rare-earth magnet (e.g., a samarium cobalt magnet) is preferably used, but the types of magnets that can be used in the rotor 3 are not limited to this. The rotor 3 is housed in the rotor housing portion 20 of the stator 1 (described later) and is configured to rotate around the rotation support shaft as the rotation center. Furthermore, in this embodiment, by sequentially applying a drive pulse to any one of the three coils (first coil C1, second coil C2, and third coil C3) described later, the rotor 3 can rotate within the rotor housing 20 in either the forward direction (i.e., clockwise) or the reverse direction (i.e., counterclockwise) at a predetermined step angle (60 degrees in this embodiment). The rotating support shaft is connected to a gear (not shown) that constitutes a gear train mechanism for moving the hands of a time display device (such as a watch or clock), and the rotation of the rotor 3 causes the gear to rotate. Furthermore, the rotor provided in the stepper motor 100 is not limited to a magnet that is radially bipolar magnetized. For example, a magnet with six poles, or more poles than bipolar magnets, may be radially magnetized.

[0025] In one embodiment, the stator 1 includes a straight portion 12 extending in a first direction (hereinafter referred to as the length direction L), and an extension portion disposed at at least one end of the straight portion 12 and extending in a direction intersecting the extension direction (length direction L) of the straight portion 12. In another embodiment, the extension portion includes a first extension portion 13 and a second extension portion 14 respectively disposed at both ends of the straight portion 12 in the length direction L. Figure 4A and Figure 4BIn this embodiment, the protrusion located at the right end of the straight section 12 is designated as the first protrusion 13, and the protrusion located at the left end of the straight section 12 is designated as the second protrusion 14. The first protrusion 13 and the second protrusion 14 extend in a direction intersecting the length direction L of the straight section 12. One end of each protrusion (the first protrusion 13 and the second protrusion 14) is formed as a straight line extending in a direction orthogonal to the straight section. That is, the protrusions (the first protrusion 13 and the second protrusion 14) extend in a direction orthogonal to the straight section 12. In this embodiment, "the direction intersecting the length direction L of the straight section 12" refers to a direction orthogonal to the length direction L. In this embodiment, in... Figure 4A In this design, the extension direction of the first protruding portion 13 and the second protruding portion 14 is defined as the width direction W. The first protruding portion 13 and the second protruding portion 14 extend laterally from both ends of the straight portion 12 towards the left and right sides of the width direction W (in...). Figure 4A The middle (top and bottom) extends out by approximately the same length, such as Figure 4A As shown, the stator 1 in the embodiment is generally H-shaped.

[0026] The stator 1 is formed, for example, from a high-permeability material such as permalloy. The linear portion 12 constitutes the central yoke in the stepper motor 100. In an embodiment, as... Figure 4B As shown, the straight portion 12 is taller in the thickness direction than the first protrusion 13 and the second protrusion 14 when viewed from the side. Coil holders 8 for coil boxes are respectively provided between the straight portion 12 and the first protrusion 13, and between the straight portion 12 and the second protrusion 14 (see reference). Figure 2 and Figure 3 (etc.). Furthermore, by winding between the pair of coil frames 8, a first coil C1 is formed in the straight portion 12. For example... Figure 4A and Figure 4C As shown, two screw holes 131 are formed at approximately symmetrical positions in the width direction W of the first protrusion 13. The screw-fixing supports 15, described later, are respectively located from one side (in... Figure 3 The screw 16 is inserted into each screw hole 131 from the lower side (middle side), and the screw 16 is inserted from the other side (in the middle side). Figure 3 The upper part (middle) is inserted into the support column 15. In the embodiment, the support column 15 and the screw 16 constitute the first support member 150. Figure 3 As shown, the first support member 150 is inserted approximately perpendicularly to the main surface of the first protrusion 13.

[0027] Additionally, a first coil substrate 17a is disposed on the first protrusion 13 and on the side of the straight portion 12 (see reference). Figure 1 and Figure 4CThe first coil substrate 17a has a generally semi-circular notch along the screw holes 131 to avoid the two screw holes 131. The first coil substrate 17a has a pair of connection points 171 for connecting the wire ends 11 of the first coil C1. Furthermore, in the embodiment, as... Figure 1 and Figure 2 As shown, three coil substrates 17 (first coil substrate 17a and second coil substrate 17b and third coil substrate 17c, described later) corresponding to the three coils (first coil C1, second coil C2, and third coil C3) are disposed on the first protrusion 13. Each coil substrate 17 is disposed on the first protrusion 13 with a height-adjustable spacer S, and the upper surfaces of all three coil substrates 17 are substantially flush. Therefore, when the main substrate 7 (described later) is disposed on top of the coil substrates 17, all three coil substrates 17 can be made to conduct electricity with the main substrate 7.

[0028] Furthermore, if the wire end 11 touches the end face of the coil substrate 17 (first coil substrate 17a, second coil substrate 17b, third coil substrate 17c), the wire may break. Therefore, in this embodiment, the coil holder 8 of the coil box is positioned at the same height as the upper surface of the coil substrate 17 (first coil substrate 17a, second coil substrate 17b, third coil substrate 17c), so that the wire end 11 connects to the connection point 171 of the coil substrate 17 from above, in a mountain-like manner, over the coil holder 8. Furthermore, in Figure 3 The illustration shows an example where the second coil C2 is connected to the connection point 171 of the second coil substrate 17. However, this structure is the same when all three coils (the first coil C1, the second coil C2, and the third coil C3) are connected to the connection points 171 of each coil substrate 17 (the first coil substrate 17a, the second coil substrate 17b, and the third coil substrate 17c). This prevents wire breakage. Furthermore, in this embodiment, by covering the wire end 11 (not shown) connected to the connection point 171 with a resin bonding material, the wire end 11 is protected more reliably.

[0029] In addition, such as Figure 4A and Figure 4C As shown, two screw holes 141 are formed at approximately symmetrical positions in the width direction W of the second protrusion 14. The screw-fixing supports 18, described later, are respectively located from one side (in... Figure 3 The screw 19 is inserted into each screw hole 141 from the lower side (in the middle), and the screw 19 is inserted from the other side (in the middle). Figure 3 The upper part (middle) is inserted into the support column 18. In the embodiment, the support column 18 and the screw 19 constitute the second support member 180. Figure 3 As shown, the second support member 180 is inserted approximately perpendicularly to the main surface of the second protrusion 14.

[0030] At approximately the center of the second protrusion 14 in the width direction W, and at the intersection of the straight portion 12 of the stator 1 in the assembled state of the stepper motor 100, the first side yoke 51 (described later), and the second side yoke 52, a roughly circular hole is formed to accommodate the rotor 3. In this embodiment, the rotor accommodating portion 20 has recesses 21 (notches) that open toward the rotor 3 at approximately equal intervals along the outer periphery of the rotor 3. These recesses 21 are used to maintain the rotor 3 in a stationary state; in this embodiment, six are formed on the inner circumferential surface of the rotor accommodating portion 20 of the stator 1. The index torque (holding torque) is maximized when any recess 21 is opposite to the polarization position of the rotor 3. Therefore, in the non-energized state without applied drive pulses, such as... Figure 1 As shown, the rotor 3 is stationary at a position opposite to the polarization position of the rotor 3 in any recess 21.

[0031] In addition, such as Figure 4A and Figure 4C As shown, on the side of the second protrusion 14 opposite to the first protrusion 13 (the side closest to the first protrusion 13), a first notch 142 is provided at a position corresponding to the two recesses 21 located on the end side of the recesses 21 in the width direction W of the rotor receiving portion 20. The first notch 142 is provided on both sides across the rotor 3 (the rotor receiving portion 20 that receives the rotor 3), and each first notch 142 is formed to be recessed between the two recesses 21. Furthermore, a third notch 143 is formed on the end side of the stator 1 in the length direction L, that is, on the side that is substantially parallel to the side of the second protrusion 14 where the first notch 142 is provided, away from the first protrusion 13 in this embodiment. The third notch 143 is formed to be recessed between the two recesses 21 at a position corresponding to the two recesses 21 located on the end side in the length direction L.

[0032] The first notch 142 and the third notch 143 are configured to surround the rotor 3 from three directions, and the shape around the rotor receiving portion 20 of the rotor 3 surrounded by the first notch 142 and the third notch 143 is approximately equilateral triangular. In the portions where the first notch 142 and the third notch 143 are provided, the width from the edge of the rotor receiving portion 20 to the outer edge of the second extension 14 narrows. In such a narrow portion, magnetic saturation is more likely to occur compared to other portions, resulting in increased magnetic reluctance and hindering the passage of magnetic flux. Therefore, in this embodiment, the first notch 142 and the third notch 143 function as magnetic flux limiting portions, restricting the orientation of the magnetic flux so that the orientations of the magnetic flux from the rotor 3 are spaced approximately 120 degrees apart. Furthermore, a second notch 145 is formed on the second extension 14, extending from the end side of the first notch 142 in the longitudinal direction L (first direction) of the stator 1. The shape, location, and extent of the second notch 145 are not limited to the example shown in the figures. Furthermore, details regarding the second notch 145 provided in the stepper motor 100 of the embodiment will be described later.

[0033] In the implementation method, such as Figure 1 and Figure 2 As shown, two magnetic yokes 5 (first side yoke 51 and second side yoke 52) disposed on the stepper motor 100 are respectively arranged on both sides of the straight portion 12 along the length direction L of the straight portion 12. The first side yoke 51 and the second side yoke 52 are arranged approximately to the left and right of the straight portion 12 as the center (within... Figure 5A The two magnetic yokes (with the top and bottom reversed) have the same basic structure, and are therefore simply referred to as magnetic yokes 5 unless otherwise specified. In the embodiment, the magnetic yokes 5 are formed of a high-permeability material such as permalloy. Each of the two magnetic yokes 5 has a straight portion 61, a protruding portion 62 disposed at one end of the straight portion 61 and wider than the straight portion 61, and a protruding portion 63 disposed at the other end of the straight portion 61 and wider than the straight portion 62.

[0034] A coil holder 8 for a coil box is provided between the straight portion 61 and the protruding portion 62 and between the straight portion 61 and the protruding portion 63 in each magnetic yoke 5 (see reference). Figure 2 and Figure 3 ).like Figure 2 As shown, on the left side of the straight portion 12 disposed on the stator 1 (in Figure 1 The straight portion 61 of the first side yoke 51 (as shown in the upper part of the middle) forms a second coil C2 by winding a wire between a pair of coil frames 8. Additionally, the right side of the straight portion 12 of the stator 1 (in the middle part of the upper part of the middle ... Figure 1The second yoke 52 (located on the lower side) is the same, and a third coil C3 is formed in the straight portion 61 by winding a wire between a pair of coil frames 8 disposed on the straight portion 61. Both magnetic yokes 5 are connected at one end via the first support member 150 (see reference). Figure 1 and Figure 3 It is locked at the first protrusion 13, and the other end is connected to the second support member 180 (see reference). Figure 1 and Figure 3 It stops at the second protrusion 14.

[0035] like Figure 5B As shown, in the embodiment, the protrusion 63 of the first side yoke 51 is engaged with the second support member 180 on one side of the second protrusion 14 of the stator 1 in the width direction W (in Figure 1 (The upper side is shown in the middle). Additionally, the protrusion 63 of the second side yoke 52 is engaged via the second support member 180 on the other side of the width direction W of the second protrusion 14 of the stator 1 (in the middle). Figure 1 (The lower side is shown in the image). Specifically, a screw hole 631 is provided in the protrusion 63 of the magnetic yoke 5, and the position of the screw hole 631 corresponds to the position of the screw hole 141 formed in the second protrusion 14 of the stator 1. A support column 18 is inserted through the screw hole 141 and the screw hole 631, and a screw 19 is fixed on the support column 18, so that the protrusion 63 of the magnetic yoke 5 is locked to the second protrusion 14. In addition, the protrusion 62 of the first side yoke 51 is locked to one side of the width direction W of the first protrusion 13 of the stator 1 via the first support member 150 (in the image). Figure 1 (The upper side is shown in the middle). Additionally, the protrusion 62 of the second side yoke 51 is engaged via the first support member 150 on the other side of the width direction W of the first protrusion 13 of the stator 1 (in the middle). Figure 1 (The lower side is shown in the middle). Specifically, in the protrusion 62 of the magnetic yoke 5, a generally C-shaped notch 621 is formed at a position corresponding to the screw hole 131 formed in the first protrusion 13 of the stator 1. The support column 18 is inserted through the screw hole 131 and the notch 621, and the screw 16 is locked on the support column 15, so that the protrusion 62 is locked to the first protrusion 13.

[0036] A coil substrate 17, which connects to the wire end 11 of a coil, is disposed on the protrusion 62 of each yoke 5. Specifically, a second coil substrate 17b corresponding to the second coil C2 is disposed on the protrusion 62 of the first yoke 51, and a third coil substrate 17c corresponding to the third coil C3 is disposed on the protrusion 62 of the second yoke 52. Furthermore, similar to the case of the first coil C1 disposed on the straight portion 12 of the stator 1, each coil substrate 17 (second coil substrate 17b, third coil substrate 17c) is disposed on the protrusion 62 with a spacer S (see reference). Figure 2 and Figure 3 Therefore, as Figure 2and Figure 3 As shown, the height of the three coil substrates 17 corresponding to the three coils is approximately flush. At the protrusion 62 of each yoke 5, a notch 621 of approximately semi-circular shape is formed along the outer periphery of the first support member 150 to avoid the first support member 150 that passes through the screw hole 131 of the stator 1. Furthermore, a notch with a shape approximately consistent with the notch 621 is also formed on the coil substrates 17 (second coil substrate 17b, third coil substrate 17c) mounted on the protrusion 62. Figure 1 As shown, when the three coil substrates 17 are arranged on the first protrusion 13, the notch formed on the first coil substrate 17a and the notches formed on the second coil substrate 17b and the third coil substrate 17c are opposite each other across the first support member 150, and are generally circular in shape when viewed from above, surrounding the outer periphery of the first support member 150.

[0037] As described above, the stepper motor 100 of the embodiment is a three-coil motor having three coils (first coil C1, second coil C2, and third coil C3). Compared to a two-coil motor having only two coils, this three-coil motor is a stepper motor capable of smoother needle movement (e.g., enabling scanning needle movement). Here, refer to... Figure 6 The second notch 145 formed in the second protrusion 14 of the stator 1 will be described in detail. Figure 6 In the diagram, arrows schematically represent the flow of magnetic flux from rotor 3. For example, when using a stepper motor for the hands of a clock, it is necessary to keep rotor 3 stationary at 60° intervals and move the hands in 60° steps. In the case where it is desired to move the hands in 60° steps using a three-coil motor with three coils, such as the stepper motor 100 of the embodiment, the rotor 3 is stably stationary with its magnetic poles facing the central yoke (i.e., the central yoke formed by the straight portion 12 of stator 1).

[0038] However, the flow of magnetic flux from rotor 3 should return via the shortest path. Therefore, as Figure 7 As shown in the conventional structure, with only the first notch 142 provided around the rotor housing 20, the magnetic flux flows back at a steep angle along the inner diameter of the first notch 142 (see reference). Figure 7(See the arrow shown). Therefore, when the rotor 3 is to be stationary with its magnetic poles pointing towards the first yoke 51 and the second yoke 52, the distribution of the target torque becomes unstable. That is, there is a deviation of approximately 60° between the direction along the inner diameter of the first notch 142 and the angle at which the rotor 3 is to be stationary with respect to the first yoke 51 and the second yoke 52. Therefore, it is difficult to keep the rotor 3 stationary at the specified position between the first yoke 51 and the second yoke 52. For example, it is difficult to form a stable stationary position every 60°, and in this case, it is impossible to use the stepper motor for accurate needle movement every 60°.

[0039] Regarding this, as in the embodiment, if a second notch 145 is continuously formed with the first notch 142, extending further toward the end of the stator 1 in the length direction L than the end of the stator 1 in the first notch 142 in the length direction L, then... Figure 6 As indicated by the middle arrow, the magnetic flux of rotor 3 flows back in a circuitous path that bypasses the apex of the second notch 145. This stabilizes the distribution of the target torque, enabling rotor 3 to remain stably stationary at the desired resting angle (a predetermined position). The second notch 145 can also be extended to a greater extent than... Figure 4A , Figure 4C and Figure 6 The position shown is closer to the end side of the stator along its length L. For example... Figure 6 As shown, preferably, the second notch 145 extends to the end side in the length direction L when drawing out the line connecting the rotation center of the rotor 3 to the edge portion of the recess 21 near the yoke 5 among the plurality of recesses 21 provided in the rotor housing 20. For example, the second notch 145 may also extend to a position further to the end side in the length direction L than in the example shown. Furthermore, if it cuts too far to the end side in the length direction L, magnetic flux will be difficult to flow. Therefore, it is preferable that the second notch 145 exists. Figure 6 The shaded fan-shaped area Ar1 is marked in the diagram. Furthermore, it is preferable that, from the front end to the root of the second notch 145, there is a portion that does not coincide with any of the yokes in the plan view viewed from above. That is, if the yoke 5 coincides with the second notch 145, the second notch 145 forms a path shorter than the desired path for the magnetic flux to detour, and the magnetic flux may flow back along this shortest path. Therefore, the first side yoke 51 and the second side yoke 52 are connected to the stator 1 at a position away from the second notch 145 (outside the width direction W).

[0040] Next, the function of the stepper motor 100 in this embodiment will be explained. When assembling the stepper motor 100 of this embodiment, as follows... Figure 4AThe stator 1 shown has a straight section 12 on which coil frames 8 are mounted, and winding is performed approximately evenly between the coil frames 8. Thus, a first coil C1 is formed with the straight section 12 as the center. A first coil substrate 17a is disposed at the first protrusion 13 of the stator 1, separated by a spacer S. The wire tip 11 leading from the first coil C1 is connected to a connection point 171 provided on the first coil substrate 17a, and wire bonding is performed from above the connection point using resin. Thus, the connection between the wire tip 11 and the coil substrate 17a is covered and protected by resin.

[0041] Additionally, a coil holder 8 is also mounted on the straight portion 61 of the first side yoke 51, and winding is performed approximately evenly between the coil holders 8. Thus, a second coil C2 is formed in the straight portion 61. A second coil substrate 17b is disposed at the protrusion 62 of the first side yoke 51, separated by a spacer S, so that the end 11 of the wire leading from the second coil C2 is connected to the connection point 171 provided on the second coil substrate 17b, and wire bonding is performed from above the connection portion using resin. Thus, the connection portion between the end 11 of the wire and the coil substrate 17b is covered and protected by resin. Similarly, winding is performed approximately evenly on the straight portion 61 of the second side yoke 52, forming a third coil C3. A third coil substrate 17c is disposed at the protrusion 62 of the second side yoke 52, separated by a spacer S, so that the end 11 of the wire leading from the third coil C3 is connected to the connection point 171 provided on the third coil substrate 17c, and wire bonding is performed from above the connection portion using resin. Thus, the three coil substrates 17, each connected to a wire with a coil, are arranged on the first protrusion 13 of the stator 1 with their surfaces approximately flush (see reference). Figure 2 ).

[0042] In this state, the main substrate 7 is positioned from above the coil substrate 17 onto the first protrusion 13, making the coil substrate 17 and the main substrate 7 electrically connected. Figure 2 and Figure 3 As shown, each coil substrate 17 has a terminal portion 172 for communication with the main substrate 7 at a location different from the connection point 171 of the connecting line end 11. Two terminal portions 172 are provided on the first coil substrate 17a, two on the second coil substrate 17b, and two on the third coil substrate 17c. On the main substrate 7, conductive pad portions 72 are arranged at positions corresponding to these terminal portions 172. If the main substrate 7 is positioned on the coil substrate 17 with the surface of the main substrate 7 having the pad portions 72 facing the coil substrate 17, the pad portions 72 of the main substrate 7 are connected to the corresponding terminal portions 172 of each coil substrate 17. In this state, the coil substrate 17 and the main substrate 7 are jointly secured to the first support member 150 by screwing with the screws 16 of the first support member 150.

[0043] Therefore, three coils can be stably fixed around the first support member 150 and assembled onto the stator 1, enabling a stepper motor 100 that is efficient and effective in terms of area, construction, and electrical design. Furthermore, although not shown in the figures, openings are formed on the main substrate 7 at positions corresponding to the wire bonding performed on the coil substrate 17 side, creating a structure that avoids the wire bonding. Thus, even when the wire bonding portion is raised on the surface of the coil substrate 17, the terminal portion 172 on the coil substrate 17 side and the pad portion 72 on the main substrate side maintain surface contact without wobbling, achieving stable conductivity.

[0044] Furthermore, in this embodiment, a second notch 145 is formed continuously with the first notch 142, extending further toward the end of the stator 1 in the length direction L than the end of the first notch 142 in the length direction L. Thus, as... Figure 6 As shown by the middle arrow, the magnetic flux of rotor 3 flows back in a path that bypasses the apex of the second notch 145, which enables rotor 3 to remain stably stationary at the desired angle.

[0045] As described above, according to this embodiment, the stepper motor 100 includes: a rotor 3, which is magnetized in the radial direction; a stator 1, having a straight portion 12 extending in the length direction L as a first direction, a second protrusion 14 provided at at least one end of the straight portion 12 and extending in a direction intersecting the extension direction of the straight portion 12, and a rotor receiving portion 20 provided in the second protrusion 14 and accommodating the rotor 3; two magnetic yokes 5, respectively disposed on both sides of the straight portion 12 along the length direction L of the straight portion 12; and a plurality of (three in this embodiment) coils magnetically coupled to the stator 1, a first notch 142 and a second notch 145 formed in the second protrusion 14, the first notch 142 being disposed on both sides at least across the rotor 3, and the second notch 145 extending toward the end side of the stator 1 in the length direction L of the stator 1 than the first notch 142. In the case of a three-coil motor with three coils, for example, if the rotor 3 is rotated intermittently at predetermined step intervals to move the hands of a clock, the magnetic poles are stably stationary when the rotor's magnetic poles are facing the central yoke (in the embodiment, the straight portion 12 of the stator 1 constituting the central yoke). However, if the magnetic poles are to be stationary when facing the second and third yokes on both sides (in the embodiment, the first side yoke 51 and the second side yoke 52), the distribution of the index torque tends to become unstable, and it is sometimes difficult to station the magnetic poles at the predetermined position. The main reason for this is believed to be that the magnetic flux needs to return along the shortest path. In this regard, by adopting the structure of the embodiment, the magnetic flux of the rotor 3 returns in a path that detours around the apex of the second notch portion 145, and the rotor 3 can be stably stationary at the desired stationary angle. Therefore, the rotor 3 can be stationary at the predetermined position with high precision with minimal installation space, and a stepper motor 100 that can be stationary with a 60° step interval can be realized.

[0046] Furthermore, in this embodiment, in the rotor housing 20, recesses 21 opening toward the rotor 3 are provided at approximately equal intervals along the outer periphery of the rotor 3. The second notch 145 extends to a position closer to the end in the longitudinal direction L than the line connecting the center of the rotor 3 to the edge portion of the recess 21 near the yoke 5. The magnetic flux of the rotor 3 is most easily saturated at the edge portion of the recess 21. Therefore, by forming the second notch 145 to a position closer to the end in the longitudinal direction L than the line connecting the edge portion of the recess 21 to the center of the rotor 3, the magnetic flux can be effectively deflected.

[0047] Furthermore, in this embodiment, from the front end to the root of the second notch 145, there exists a portion that does not coincide with each of the yokes 5 in a plan view viewed from above. If the yoke 5 coincides with the second notch 145, even with the second notch 145 provided, a path shorter than the intended path for the magnetic flux to detour is formed, and the magnetic flux may flow back along this shortest path. By connecting the yoke 5 to the stator 1 at a position away from the second notch 145, the magnetic flux can be properly detoured using the second notch 145.

[0048] Furthermore, in this embodiment, one end of the second protrusion 14 is formed as a straight line extending in a direction orthogonal to the straight portion. This ensures a path for the magnetic flux to meander without increasing the stator size. Therefore, the rotor 3 can be brought to a standstill with a 60° step size with minimal installation space.

[0049] Furthermore, in the second extension 14 of the embodiment, a third notch 143 is formed on the end side of the stator 1 in the longitudinal direction L. The third notch 143 and the first notch 142 surround the rotor 33 from three directions, restricting the orientation of the magnetic flux so that the orientations of the magnetic flux from the rotor 3 are spaced approximately 120 degrees apart. As a result, the orientation of the magnetic flux from the rotor 3 can be effectively restricted, allowing it to stop with high precision in 60° increments.

[0050] Furthermore, in the rotor housing 20 of the embodiment, six recesses 21 opening toward the rotor 3 are provided at approximately equal intervals along the outer periphery of the rotor 3, and the first notch 142 and the third notch 143 are respectively provided at positions corresponding to a certain recess. Thus, the first notch 142 and the third notch 143 can function as magnetic flux limiting parts, which restrict the orientation of the magnetic flux so that the orientations of the magnetic flux from the rotor 3 are respectively spaced approximately 120 degrees apart.

[0051] Furthermore, in this embodiment, the rotor receiving portion 20 of the rotor 3, which is surrounded by the third notch 143 and the first notch 142, has a shape that is approximately equilateral triangular. This effectively limits the orientation of the magnetic flux from the rotor 3, allowing it to remain stationary with high precision in 60° increments.

[0052] Furthermore, while embodiments of the present disclosure have been described above, the present disclosure is not limited to these embodiments, and various modifications can be made without departing from its spirit. For example, the shape of the yoke 5 (especially the protrusion 63) is not limited to the example shown in the figure; for example, it may be smaller in the width direction W than in the example shown in the figure, or the notch may be formed near the second notch 145. Thus, the yoke 5 (the protrusion 63 of the yoke 5) becomes a shape further away from the second notch 145. By providing the second notch 145, it is possible to prevent the formation of a path shorter than the path through which the magnetic flux is to be detoured, and the magnetic flux can be reliably returned in a detour around the apex of the second notch 145.

[0053] Furthermore, in this embodiment, an example is shown where a rounded corner is provided at the apex of the second notch 145. However, without hindering the processing of forming the second notch 145, the apex may also be a sharp shape without a rounded corner. Additionally, the specific shape of the second notch 145 is not limited to the example shown in the figure.

[0054] Furthermore, in the embodiment, the stepper motor 100 is illustrated with three coils magnetically coupled to the stator 1, but multiple coils are permissible and not limited to three. For example, this disclosure can also be applied even without the structure of the first coil C1 formed in the straight portion 12 of the three coils shown in the embodiment.

[0055] Furthermore, in the embodiment, the stepper motor 100 is illustrated as being used in clocks and watches, but the devices that can use the stepper motor 100 are not limited to this.

[0056] The above description describes several embodiments of this disclosure, but the scope of this disclosure is not limited to the above embodiments, but includes the scope of disclosure set forth in the claims and its equivalents.

Claims

1. A stepper motor wherein, Possessing: a rotor magnetized in a radial direction; a stator having a linear portion extending in a first direction, a protruding portion provided on at least one end side of the linear portion and protruding in a direction intersecting the extending direction of the linear portion, and a rotor accommodating portion provided on the protruding portion and accommodating the rotor; two yokes respectively arranged on both sides of the linear portion along the length direction of the linear portion; and a plurality of coils provided in magnetic coupling with the stator, a first notch portion and a second notch portion are formed in the protruding portion, the first notch portion is provided on both sides at least through the rotor, and the second notch portion extends toward the end portion side in the first direction of the stator than the first notch portion.

2. The stepping motor according to claim 1, wherein in the rotor accommodating portion, recesses are provided toward the rotor at substantially equal intervals along the outer periphery of the rotor, the second notch portion extends to a position closer to the end portion side in the first direction than a line connecting the center of the rotor and an edge portion of the recess close to the yoke.

3. The stepping motor according to claim 1, wherein from the front end to the root of the second notch portion, there is a portion that does not coincide with the respective yokes in a plan view when viewed from above.

4. The stepping motor according to claim 1, wherein one end portion of the protruding portion is formed in a linear shape extending in a direction orthogonal to the linear portion.

5. The stepping motor according to claim 1, wherein in the protruding portion, a third notch portion is formed on the end portion side in the first direction of the stator, the third notch portion and the first notch portion surround the rotor from three directions, and restrict the direction of magnetic flux so that the directions of magnetic flux from the rotor are separated by substantially 120 degrees, respectively.

6. The stepping motor according to claim 5, wherein in the rotor accommodating portion, six recesses are provided toward the rotor at substantially equal intervals along the outer periphery of the rotor, the first notch portion and the third notch portion are respectively provided at positions corresponding to the recesses at intervals.

7. The stepping motor according to claim 5, wherein the shape around the rotor accommodating portion of the rotor surrounded by the third notch portion and the first notch portion is substantially an equilateral triangle. Possessing the stepping motor according to any one of claims 1 to 7.

8. A timepiece, wherein, ​

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