Stepping motor

Abstract

The rotor is precisely positioned and stationary within the minimum required mounting space. [Solution] The stepping motor 100 comprises a rotor 3 magnetized in the radial direction, a stator 1 having a straight 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 straight portion 12 and extending in a direction intersecting the longitudinal direction L on which the straight portion 12 extends, and a rotor receiving portion 20 provided on the second protruding portion 14 for receiving the rotor 3, two yokes 5 arranged on both sides of the straight portion 12 along the longitudinal direction L of the straight portion 12, and a plurality of coils provided magnetically coupled to the stator 1, wherein the protruding portion has a first notch 142 provided on at least both sides of the rotor 3 and a second notch 145 extending toward the end side in the first direction of the stator 1 from the first notch 142.

Description

Technical Field

[0004] , , , , , ,

[0005] , , ,

[0003] , , , ,

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

Background Art

[0002] A stepping motor has a step angle required according to its application. For example, when a stepping motor is used as a motor for driving the hands of a clock, it needs to operate in predetermined steps. In this regard, conventionally, in a two-coil stepping motor, it is known to provide one magnetic flux saturation portion and two recesses (slit portions in Patent Document 1) in the stator (see 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, in the case of a triple-coil motor having three coils, for example, when trying to drive the hands of a clock by rotating the rotor at equal intervals and intermittently in predetermined steps, when the magnetic poles of the rotor face the central yoke, the magnetic poles can stably stop. However, when trying to stop the magnetic poles facing the second and third yokes on both sides, the distribution of the index torque tends to become unstable, and it may be difficult to stop the magnetic poles at a predetermined position. This is considered to be caused by the fact that the magnetic flux tries to flow back through the shortest path.

[0005] The present invention has been made in view of the above circumstances, and an object thereof is to provide a triple-coil stepping motor capable of accurately stopping a rotor at a predetermined position with a minimum mounting space.

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 extending in a first direction, an overhang portion provided on at least one end of the straight portion and extending in a direction intersecting the extending direction of the straight portion, and a rotor receiving portion provided on the overhang portion for receiving the rotor, two yokes arranged on both sides of the straight portion along the longitudinal direction of the straight portion, and a plurality of coils provided magnetically coupled to the stator, wherein the overhang portion is characterized in that it has a first notch provided on at least both sides of the rotor and a second notch that extends toward the end of the stator in the first direction from the first notch. [Effects of the Invention]

[0007] According to the present invention, the rotor can be precisely stationary in a predetermined position with minimal mounting space. [Brief explanation of the drawing]

[0008] [Figure 1] This is a plan view of a stepping motor according to an embodiment. [Figure 2] This is a perspective view of a stepping motor according to an embodiment. [Figure 3] This is a cross-sectional view of the main part of the stepping motor along the line III-III in Figure 1. [Figure 4] (a) is a plan view of the stator, (b) is a side view of the stator as seen from the direction of arrow b in (a), (c) is a plan view of the stator with the coil and coil substrate mounted on it, and (d) is a front view of the stator as seen from the direction of arrow d in (c). [Figure 5] (a) is a plan view of the first side yoke and the second side yoke, (b) is a plan view of the first side yoke and the second side yoke with the coil and coil substrate mounted on them, and (c) is a front view of the first side yoke and the second side yoke as seen from the direction of arrow c in (b). [Figure 6] This is a plan view illustrating the second notch formed in the second protruding portion of the embodiment and the flow of magnetic flux from the rotor. [Figure 7] This is a plan view illustrating the notch formed in the conventional second protrusion and the flow of magnetic flux from the rotor. [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 7. 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 Figures 1 and 2, 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 (the first side yoke 51 and the 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 magnetized with two poles in the radial direction. For example, Figure 1 shows that the poles are different in the white-out area and the hatched area of ​​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 rotatably arranged with 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 magnetized in the radial direction.

[0012] In this embodiment, the stator 1 includes a straight portion 12 extending in a first direction (hereinafter referred to as the longitudinal direction L), and an overhang portion provided at least at one end of the straight portion 12 and extending in a direction intersecting the direction of extension of the straight portion 12 (longitudinal direction L). In this embodiment, the overhang portion includes a first overhang portion 13 and a second overhang portion 14, which are provided at both ends of the straight portion 12 in the longitudinal direction L. In Figures 4(a) and 4(b), the overhang portion provided at the right end of the straight portion 12 is referred to as the first overhang portion 13, and the overhang portion provided at the left end of the straight portion 12 is referred to as the second overhang portion 14. The first overhang portion 13 and the second overhang portion 14 extend in a direction intersecting the longitudinal direction L of the straight portion 12. One end of each overhang portion (first overhang portion 13 and second overhang portion 14) is formed in a straight line extending in a direction perpendicular to the straight portion. In other words, the protruding portions (first protruding portion 13 and second protruding portion 14) extend in a direction perpendicular to the straight portion 12, and in this embodiment, the "direction intersecting the longitudinal direction L of the straight portion 12" is the direction perpendicular to the longitudinal direction L. In this embodiment, the direction of protrusion of the first protruding portion 13 and the second protruding portion 14 is the width direction W in Figure 4(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 (up and down in Figure 4(a)) in the width direction W by approximately the same length, and as shown in Figure 4(a), the stator 1 in this embodiment is approximately 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 2 and 3, etc.). By winding wire between these pair of coil frames 8, the first coil C1 is formed in the straight portion 12. 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 3), and a screw 16 is inserted through the support post 15 from the other side (the upper side in Figure 3). In this embodiment, the support post 15 and the screw 16 constitute the first support member 150. As shown in Figure 3, 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 17a (see Figures 1 and 4(c)) is positioned on the first protruding portion 13, on the side of the straight portion 12, with a substantially semicircular notch formed along the screw holes 131 to avoid the two screw holes 131. The first coil substrate 17a 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 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, 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), there is a risk of wire breakage. 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 3 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 17 (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 (not shown) is provided, which 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.

[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 3), and a screw 19 is inserted through the support column 18 from the other side (the upper side in Figure 3). In this embodiment, the support column 18 and the screw 19 constitute the second support member 180. As shown in Figure 3, the second support member 180 is inserted substantially perpendicular to the main surface of the second protruding portion 14.

[0017] It is approximately the central part in the width direction W of the second overhanging portion 14. In the assembled state of the stepping motor 100, at the position where the straight portion 12 of the stator 1 intersects with the first side yoke 51 and the second side yoke 52, which will be described later, a rotor receiving portion 20 that is a substantially circular hole and receives the rotor 3 is formed. In the rotor receiving portion 20 in the embodiment, recesses 21 (notches) that open toward the rotor 3 are provided at substantially equal intervals along the outer periphery of the rotor 3. The recesses 21 are for maintaining the stationary state of the rotor 3, and six of them are formed on the inner peripheral surface of the rotor receiving portion 20 of the stator 1 in the embodiment. The index torque (holding torque) of the rotor 3 becomes the largest when any one of the recesses 21 and the polarization position of the rotor 3 are opposed to each other. For this reason, in the non-powered state where no drive pulse is applied, the rotor 3 stops at the position where any one of the recesses 21 and the polarization position of the rotor 3 are opposed to each other, as shown in FIG. 1.

[0018] Also, as shown in FIGS. 4(a) and 4(c), on the side (the side proximal to the first overhanging portion 13) of the second overhanging portion 14 that faces the first overhanging portion 13, at the position corresponding to between the two recesses 21 located on the end side in the width direction W among the recesses 21 provided in the rotor receiving portion 20, a first notch portion 142 is provided. The first notch portions 142 are provided on both sides sandwiching the rotor 3 (the rotor receiving portion 20 that receives the rotor 3), and each first notch portion 142 is formed so as to bite into the space 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 that is substantially parallel to the side where the first notch portion 142 is provided in the second overhanging portion 14 in the embodiment, a third notch portion 143 is formed. The third notch portion 143 is formed at the position corresponding to between the two recesses 21 provided on the end portion side in the longitudinal direction L so as to bite into the space between the two recesses 21.

[0019] The first notch 142 and the third notch 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 142 and the third notch 143 is substantially an equilateral triangle. At the locations 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 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 obstructed. Thereby, in the embodiment, the first notch 142 and the third notch 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. Further, in the second overhanging portion 14, a second notch 145 extending toward the end side in the longitudinal direction L (first direction) of the stator 1 rather than the first notch 142 is formed. The shape, provided position, and range of the second notch 145 are not limited to the illustrated example. Details of the second notch 145 provided in the stepping motor 100 of the embodiment will be described later.

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

[0021] In each yoke 5, a coil frame 8 of the coil case is installed between the straight portion 61 and the protruding portion 62, and between the straight portion 61 and the protruding portion 63, respectively (see Figures 2 and 3). As shown in Figure 2, a second coil C2 is formed in the straight portion 61 of the first side yoke 51, which is located on the left side (upper side in Figure 1, etc.) of the straight portion 12 of the stator 1, by winding wire between a pair of coil frames 8. Similarly, in the second side yoke 52, which is located on the right side (lower side in Figure 1, etc.) of the straight portion 12 of the stator 1, a third coil C3 is formed in the straight portion 61 by winding wire between a pair of coil frames 8 installed on the straight portion 61. Both yokes 5 are secured at one end to the first overhang 13 via the first support member 150 (see Figures 1 and 3), and at the other end to the second overhang 14 via the second support member 180 (see Figures 1 and 3).

[0022] As shown in Figure 5(b), in this embodiment, the protruding portion 63 of the first side yoke 51 is locked to one side (upper side in Figure 1, etc.) of the second protruding portion 14 of the stator 1 in the width direction W via the 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, etc.) of the second protruding portion 14 of the stator 1 in the width direction W via the 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, etc.) 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, etc.) 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] 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. Each yoke 5 has a protruding portion 62, and a substantially semicircular notch 621 is formed along the outer circumference of the first support member 150 so as to avoid the first support member 150 which is inserted into the screw hole 131 of the stator 1. The coil substrates 17 (second coil substrate 17b, third coil substrate 17c) mounted on the protruding portion 62 also have notches formed in a shape that substantially matches this notch 621. As shown in Figure 1, etc., when the three coil substrates 17 are arranged side by side on the first protruding portion 13, the notch formed in the first coil substrate 17a and the notches formed in the second coil substrate 17b and third coil substrates 17c face each other across the first support member 150, and in a top view they form a substantially circular shape that surrounds the outer circumference of the first support member 150.

[0024] As described above, the stepping motor 100 of the embodiment is a triple-coil motor equipped with three coils (a first coil C1, a second coil C2, and a third coil C3). Compared to a double-coil motor equipped with two coils, such a triple-coil motor is a stepping motor that can move the hands more smoothly (for example, it can achieve sweep movement). Now, with reference to Figure 6, the second notch 145 formed in the second protruding portion 14 of the stator 1 will be described in detail. In Figure 6, the flow of magnetic flux from the rotor 3 is schematically shown by arrows. For example, when a stepping motor is used to move the hands of a clock, it is necessary to stop the rotor 3 at resting positions every 60° and move the hands in 60° steps. When attempting to move the hands in 60° steps with a triple-coil motor equipped with three coils, such as the stepping motor 100 of the embodiment, the rotor 3 will remain stably stationary when the magnetic poles of the rotor 3 are directed toward the central yoke (i.e., the center yoke composed of the straight portion 12 of the stator 1).

[0025] However, the magnetic flux flow from the rotor 3 attempts to recirculate along the shortest path. Therefore, as in the conventional configuration shown in Figure 7, when only the first notch 142 is provided around the rotor receiving portion 20, the magnetic flux recirculates at a steep angle along the inner diameter of the first notch 142 (see the arrow in Figure 7). As a result, when attempting to stationary the magnetic poles of the rotor 3 toward the first side yoke 51 and the second side yoke 52, the index torque distribution becomes unstable. That is, the direction along the inner diameter of the first notch 142 is off by about 60° from the angle at which the rotor 3 is to be stationary toward the first side yoke 51 and the second side yoke 52. Therefore, it is difficult to stationary the rotor 3 at a predetermined position by the first side yoke 51 and the second side yoke 52. For example, it is difficult to form stationary stable positions at 60° intervals, and in this case, the stepping motor could not be used for precise needle movement at 60° intervals.

[0026] In this regard, as in the embodiment, when a second notch 145 is formed continuously with the first notch 142, extending further toward the end in the longitudinal direction L than the end of the stator 1 in the longitudinal direction L at the first notch 142, the magnetic flux of the rotor 3 circulates in a path that bypasses the apex of the second notch 145, as shown by the arrow in Figure 6. This stabilizes the distribution of index torque, allowing the rotor 3 to be stably stopped at the desired angle (predetermined position). The second notch 145 may extend further toward the end in the longitudinal direction L of the stator than the position shown in Figures 4(a), 4(c), and 6. The second notch 145 preferably extends to the end of the longitudinal direction L when a line is drawn connecting the rotation center of the rotor 3 and the edge of the recess 21 closest to the yoke 5 among the multiple recesses 21 provided in the rotor receiving portion 20, as shown in Figure 6. For example, the second notch 145 may extend even further to the end of the longitudinal direction L than in the illustrated example. However, if the notch is cut too far to the end of the longitudinal direction L, the magnetic flux will not flow easily. For this reason, the second notch 145 preferably lies within the fan-shaped region Ar1 shaded in Figure 6. Furthermore, it is preferable that there is a portion of the second notch 145 from its tip to its base that does not overlap with each yoke in a plan view from above. In other words, if the yoke 5 overlaps with the second notch 145, the provision of the second notch 145 creates a shorter path than the route to which the magnetic flux is intended to be rerouted, and there is a risk that the magnetic flux will recirculate along this shortest path. For this reason, the first side yoke 51 and the second side yoke 52 are connected to the stator 1 at a position farther away from the second notch 145 (outside in the width direction W).

[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 a wire end 11 drawn 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 portion with resin. In this way, the connection portion of the wire end 11 to the coil substrate 17 is covered with resin and protected.

[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 wire bonding is performed from above the connection portion with resin. 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 wire bonding is performed from above the connection portion using resin. 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 2).

[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. There are two terminal portions 172 on the first coil board 17a, two on the second coil board 17b, and two on the third coil board 17c. The main board 7 has conductive pad portions 72 at positions corresponding to each of these terminal portions 172. When the main board 7 is placed on the coil board 17 so that the surface on which the pad portions 72 are formed faces the coil board 17, the pad portions 72 of the main board 7 are connected to the corresponding terminal portions 172 of each coil board 17. In this state, the coil substrate 17 and the main substrate 7 are fastened together at the first support member 150 by tightening the screws 16 of the first support member 150.

[0030] 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. Although not shown in the diagram, the main board 7 has openings formed at positions corresponding to the wire bonding applied to the coil board 17, thus avoiding the wire bonding. As a result, even if the wire bonding portion is formed as a raised area on the surface of the coil board 17, the terminal portion 172 on the coil board 17 and the pad portion 72 on the main board can make surface contact without rattling, achieving stable conductivity.

[0031] Furthermore, in this embodiment, a second notch 145 is formed continuously with the first notch 142, extending further toward the end in the longitudinal direction L than the end of the stator 1 in the longitudinal direction L at the first notch 142. As a result, the magnetic flux of the rotor 3 recirculates in a path that bypasses the apex of the second notch 145, as shown by the arrow in Figure 6, allowing the rotor 3 to be stably stopped at the desired angle.

[0032] 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 portion 12 extending in the longitudinal direction L which is the first direction, a second protruding portion 14 provided on at least one end side of the straight portion 12 and extending in a direction intersecting the extending direction of the straight portion 12, and a rotor receiving portion 20 provided on the second protruding portion 14 for receiving the rotor 3, two yokes 5 arranged on both sides of the straight portion 12 along the longitudinal direction L of the straight portion 12, and a plurality (three in this embodiment) of coils provided magnetically coupled to the stator 1, wherein the second protruding portion 14 has a first notch 142 provided on at least both sides of the rotor 3 and a second notch 145 extending toward the end side in the longitudinal direction L of the stator 1 from the first notch 142. As a result, the magnetic flux of the rotor 3 recirculates along a path that bypasses the apex of the second notch 145, allowing the rotor 3 to be stably stopped at the desired angle. Therefore, the rotor 3 can be stopped precisely at a predetermined position with minimal mounting space, and a stepping motor 100 that stops in 60° steps can be realized.

[0033] Furthermore, in this embodiment, the rotor receiving portion 20 has recesses 21 that open toward the rotor 3 along the outer circumference of the rotor 3 at approximately equal intervals, and the second notch 145 extends to the end side in the longitudinal direction L beyond the line connecting the center of the rotor 3 and the edge portion of the recess 21 that is close to the yoke 5. The magnetic flux of the rotor 3 is most likely to saturate at the edge portion of the recess 21. For this reason, by forming the second notch 145 to the end side in the longitudinal direction L beyond the line connecting the edge portion of the recess 21 and the center of the rotor 3, the magnetic flux can be effectively diverted.

[0034] Furthermore, in this embodiment, there is a portion of the second notch 145 from its tip to its base that does not overlap with each yoke 5 in a plan view from above. If the yoke 5 overlaps with the second notch 145, even if the second notch 145 is provided, a shorter path than the route to which the magnetic flux is originally intended to be rerouted will be formed, and there is a risk that the magnetic flux will recirculate using this shortest path. By connecting the yoke 5 to the stator 1 at a position further away from the second notch 145, the magnetic flux can be appropriately rerouted by the second notch 145.

[0035] Furthermore, one end of the second protruding portion 14 in the embodiment is formed in a straight line extending in a direction perpendicular to the straight portion. This ensures a route for diverting magnetic flux without increasing the size of the stator. As a result, the rotor 3 can be stopped accurately in 60° steps with minimal mounting space.

[0036] Furthermore, the second protruding portion 14 of the embodiment has a third notch 143 formed on the end side in the longitudinal direction L of the stator 1. The third notch 143 and the first notch 142 surround the rotor 3 from three directions, restricting the direction of the magnetic flux from the rotor 3 so that it is directed approximately 120 degrees in each direction. This effectively restricts the direction of the magnetic flux from the rotor 3, allowing it to be stopped with precision in 60° steps.

[0037] Furthermore, the rotor receiving portion 20 of the embodiment is provided with six recesses 21 that open toward the rotor 3 along the outer circumference of the rotor 3 at approximately equal intervals, and the first notch 142 and the third notch 143 are each provided at positions corresponding to either of the recesses. As a result, the first notch 142 and the third notch 143 can function as magnetic flux restricting portions that restrict the direction of the magnetic flux from the rotor 3 so that it is directed approximately 120 degrees away from each other.

[0038] Furthermore, in this embodiment, the shape of the area around the rotor receiving portion 20 of the rotor 3, surrounded by the third notch 143 and the first notch 142, is approximately an equilateral triangle. This effectively restricts the direction of the magnetic flux from the rotor 3, allowing it to be stopped precisely in 60° steps.

[0039] 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, the shape of the yoke 5 (especially the protruding portion 63) is not limited to the illustrated example, and for example, the width W may be smaller than in the illustrated example, or a notch may be formed in the part closer to the second notch 145. This will result in a shape in which the yoke 5 (the protruding portion 63 of the yoke 5) is further away from the second notch 145, preventing the formation of a path shorter than the route to which the magnetic flux is to be rerouted by providing the second notch 145, and ensuring that the magnetic flux is rerouted to bypass the apex of the second notch 145.

[0040] Furthermore, although the embodiment shows an example in which a radius (R) is provided at the apex of the second notch 145, the apex may have a pointed shape without a radius (R), provided that it does not hinder the processing of forming the second notch 145. Also, the specific shape of the second notch 145 is not limited to the illustrated example.

[0041] 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.

[0042] 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.

[0043] 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]

[0044] 1... Stator, 3... Rotor, 5... Yoke, 12... Straight section, 14... Second protruding section (protruding section), 20... Rotor receiving section, 100... Stepping motor, 142... First notch, 145... Second notch, C1... First coil, C2... Second coil, C3... Third coil

Claims

1. A rotor magnetized in the radial direction, A stator having a straight portion extending in a first direction, an overhang portion provided at least on one end of the straight portion and extending in a direction intersecting the direction of extension of the straight portion, and a rotor receiving portion provided on the overhang portion for receiving the rotor, Two yokes are arranged on both sides of the straight portion, along the longitudinal direction of the straight portion, The stator comprises a plurality of coils that are magnetically coupled to the stator, The protruding portion is formed with a first notch provided on at least both sides of the rotor, and a second notch extending from the first notch toward the end of the stator in the first direction. Stepping motor.

2. The rotor receiving portion is provided with recesses that open toward the rotor at approximately equal intervals along the outer circumference of the rotor. The second notch extends to the end side in the first direction beyond the line connecting the center of the rotor and the edge portion of the recess that is close to the yoke. The stepping motor according to claim 1.

3. From the tip to the base of the second notch, there is a portion that does not overlap with each of the yokes when viewed from above in a plan view. The stepping motor according to claim 1.

4. One end of the protruding portion is formed in a straight line extending in a direction perpendicular to the straight portion. The stepping motor according to claim 1.

5. A third notch is formed in the protruding portion on the end side in the first direction of the stator. The third and first notches surround the rotor from three directions, restricting the direction of the magnetic flux from the rotor so that it is directed approximately 120 degrees in each direction. The stepping motor according to claim 1.

6. The rotor receiving portion has six recesses that open toward the rotor, arranged at approximately equal intervals along the outer circumference of the rotor. The first and third notches are each provided at positions corresponding to either of the recesses. The stepping motor according to claim 5.

7. The shape of the area around the rotor receiving portion of the rotor, surrounded by the third notch and the first notch, is approximately an equilateral triangle. The stepping motor according to claim 5.

Images