JP2002277565A - Step motor for timepiece - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a step motor for a timepiece equipped with a complete yoke and a coil winding core structure constituting a magnetic circuit capable of being stably driven at a remarkably low consumption power value as compared with a conventional one. SOLUTION: This step motor for a timepiece is provided with a rotor 11 comprising a rotor magnet 11a and a rotor shaft 11b, a complete yoke 9 provided with screw holes and a rotor hole 11a for installing the rotor 11, and a coil winding core 1 having screw holes with a coil wound. The step motor is characterized in that a step part is formed on the complete yoke 9 or the winding core 1 to connect the complete yoke 9 to the winding core 1 at the step part through the screw holes, and the coil winding core side surface of the winding core 1 is tightly fitted to the complete yoke side surface of the complete yoke 9.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a timepiece step motor used for an electronic timepiece or the like, and more particularly to a structure of a completed yoke and a coil core of a timepiece step motor.

[0002]

2. Description of the Related Art In a conventional analog electronic timepiece,
A battery or power generation mechanism is built in as its power source,
In the case of using a battery, after a certain period of time, the battery is consumed due to the life of the built-in battery, and the function of the analog electronic timepiece stops. For this reason, it is necessary to replace a depleted battery every time, but it is difficult for ordinary users to replace the battery, so it is necessary to ask a specialized company, and the user needs time and money to replace the battery In addition, when the battery is consumed when necessary, the battery cannot be replaced immediately, which is a serious problem in use.

[0003] As described above, the consumption of the battery is a major problem for the user, and in recent years, in analog electronic timepieces, studies have been made to extend the life of the battery in order to reduce the trouble of replacing the battery. In order to achieve a longer battery life, it is necessary to reduce power consumption.

[0004] In addition, in an analog electronic timepiece with a built-in power generation means such as a solar cell type power generation, a thermoelectric element power generation, or a mechanical power generation for rotating a rotary weight to completely eliminate the trouble of replacing a battery, the user may be required to use the analog electronic timepiece. Power generation conditions are different, and it is difficult to always generate necessary and sufficient power. Therefore, during the period during which power cannot be generated, the clock is usually driven by the power stored in the built-in capacitor or the secondary battery, so in order to always display accurate time regardless of the power generation conditions of the clock, It is necessary to reduce power consumption even in an analog electronic timepiece with a built-in power generation mechanism.

[0005] The mechanism of an analog electronic timepiece can be summarized as follows:
The time is displayed by intermittently driving a clock step motor in accordance with a reference signal generated by a crystal oscillator or the like and transmitting the movement of the step motor to a pointer via a gear.

[0006] The electric power is roughly divided into a circuit portion for generating a reference signal including a crystal oscillator and the like, and a step motor portion for moving a pointer. In recent analog electronic timepieces, the power consumption is smaller than the power consumption of the step motor part because the circuit part is a semiconductor integrated circuit. Therefore, since most of the power consumption is consumed by driving the clock step motor for hand movement, the effect of reducing the power consumption of the clock step motor on the overall power consumption of the watch is extremely large. Therefore, countermeasures are desired.

FIG. 6 is a plan view showing a schematic structure of a conventional timepiece step motor, particularly a two-pole step motor.

As shown in FIG. 6, the two-pole step motor is provided with a rotor 109 including a rotor shaft 109b and a rotor magnet 109a having a rotation axis perpendicular to the plane of FIG. Completed yoke 107 made of a material having a high magnetic permeability and having a rotor hole 111, and coil 10 for excitation made of a material having a high magnetic permeability.
3 is wound around the coil core 101.

A gap 137 exists between the completed yoke 107 and the coil core 101, and the size of the gap 137 is about 0.1 mm. The gap 13 of about 0.1 mm
The reason for the existence of 7 is that the general tolerance of watch parts is 0.
03mm, and the completed yoke 1
07 and the coil core 101 so that they can be assembled without overlapping.

The completed yoke 107 and the coil core 101 are
Each has a screw hole 105, and is overlapped so that the screw holes coincide with each other, and tightened by screws (not shown) to fix the completed yoke 107 and the coil core 101, and to connect them magnetically to form a magnetic circuit. Make up.

The completed yoke 107 includes a first yoke component 125 made of a material having a high magnetic permeability, a second yoke component 127 made of a material having a high magnetic permeability, and a material having a low magnetic permeability or a nonmagnetic material. The first yoke part 125 and the second yoke part 127 have a connection part 129.
9.

The rotor magnet 109a is made of a ferromagnetic material, and is magnetized to two poles in a direction perpendicular to the rotation axis, and has a disk shape having a center hole into which the rotor shaft 109b is fitted.

Although not shown, the rotor hole 11
The inner circumference of 1 has a holding torque setting means for setting an initial phase angle and a holding torque.

Further, the rotor 109 is provided with the rotor hole 1
11, both ends of the rotor shaft 109b are supported by bearings (not shown) so as to be located at the center of the rotor shaft 109b.
b has a gear (not shown), and is configured to transmit the rotational movement of the rotor 109 to the pointer via the gear.

In the timepiece stepping motor having such a configuration, a driving voltage is applied to the coil 103 so that a positive current and a negative current are alternately applied to the coil 103, so that the magnetic field in the rotor hole 111 follows the positive and negative currents. Is generated, and the rotor 109 having the magnetized rotor magnet 109a is rotated by 180 degrees (one step at a time). In the following description, it will rotate counterclockwise.

The power consumption of the timepiece stepping motor is equal to the time required for the clocking stepper motor coil 103 per unit time.
And the product of the amount of current flowing through the battery and the applied battery voltage. Here, since the battery voltage is almost constant, reducing the power consumption of the timepiece step motor means how to reduce the current flowing through the coil 103 while satisfying the drive characteristics required for the timepiece step motor. Can be.

Further, one-step movement of the step motor for a timepiece will be described in detail. The rotor 109 is rotated in the forward direction (reverse direction) by an initial phase angle 115 with respect to the direction 113 of the magnetic field generated inside the rotor hole 111 by the magnetic flux generated by the coil 103 to drive the rotor 109 by the formed holding torque. Clockwise), that is, the direction 11 of the magnetic pole of the rotor magnet 109a.
It is stationary at position 7.

Here, the initial phase angle 115 is equal to the rotor 10 angle.
9 is defined as the angle between the direction 113 of the magnetic field generated inside the rotor hole 111 by the magnetic flux generated by the coil 103 and the direction 117 of the magnetic pole of the rotor magnet 109a at the rotor stationary position.

In this state, the rotor 109 is attached to the coil 103.
When a current flows in the direction in which the rotor rotates forward, a magnetic flux generated by the coil 103 is generated in the coil core 101, and as a result, the rotor hole 1
A magnetic field is generated inside 11. Then, a rotation torque is generated in the rotor 109 by an interaction between the generated magnetic field and the permanent magnetization amount of the rotor magnet 109a, and the rotor 109 starts rotating against the holding torque. When a current flows through the coil 103 for a predetermined time, the rotor 109 rotates 180 degrees and stops at the next stationary position.

[0020]

Next, the problem to be solved by the present invention will be described in detail with reference to FIG. In order to reduce the total thickness of the timepiece, a step 135 is provided on the completed yoke 107, and the coil core 101 is fixed to the step 135 with screws 133. The thickness of the step 135 is, for example, about 0.25 mm, which is half the thickness of the completed yoke 107 of 0.5 mm.

Then, the completed yoke 107 and the coil core 1
01 in the magnetic circuit composed of
At 35, the magnetic path is narrowed due to the reduced thickness, and the magnetic flux 131 concentrates on the step 135.

Due to the concentration of the magnetic flux, the magnetic flux 131 leaks into the gap 137 in a region sandwiched between the completed yoke side face 121 and the coil core side face 123, and a large amount of magnetic flux passes through the gap 137. The resistance Rm increases, and the generated magnetic flux Φ is obtained by a value (calculation formula Φ = N × I / Rm) obtained by dividing the product of the number of coil turns N and the current value I flowing through the coil by the magnetic resistance Rm of the magnetic circuit. In order to obtain the magnetic flux Φ required to generate the required torque for rotating the rotor (not shown in FIG. 7), the magnetic resistance Rm increases.

Since the magnetic resistance Rm increases as described above, the current value I flowing through the coil must be increased by the amount corresponding to the increase in the magnetic resistance, causing an increase in the current consumption of the step motor for a timepiece. Power consumption.

[Object of the Invention] An object of the present invention is to solve the above-mentioned problems and to provide a completed yoke and a coil core which constitute a magnetic circuit which can be driven stably with a significantly lower power consumption value as compared with the prior art. An object of the present invention is to provide a timepiece step motor having a structure.

[0025]

In order to achieve the above-mentioned object, a timepiece step motor according to the present invention employs the following means.

A step motor for a timepiece according to the present invention has a rotor comprising a rotor magnet and a rotor shaft, a completed yoke provided with a screw hole and a rotor hole for installing the rotor, and a coil having a screw hole and having a coil wound thereon. A step motor for a timepiece, comprising: a stepped portion provided in the completed yoke or the coil core, and connecting the completed yoke and the coil core through the screw hole at the stepped portion. The side surface of the coil core of the coil core and the side surface of the completed yoke of the completed yoke are in close contact with each other.

Further, the step motor for a timepiece of the present invention comprises:
The side surface where the side surface of the coil core and the side surface of the completed yoke are in close contact is on a straight line passing through the center of the screw hole.

[Operation] In the timepiece stepping motor of the present invention, the side surface of the coil core and the side surface of the completed yoke are in close contact with each other without any gap. In the present invention, since the side surface of the coil core and the side surface of the completed yoke are in close contact with each other without any gap, the concentration of magnetic flux due to the narrowing of the magnetic path in the conventional technology does not occur, and the magnetic resistance of the magnetic circuit can be reduced. As a result, a magnetic circuit that can be driven stably can be obtained, and the current value flowing through the coil can be reduced, so that low power consumption of the step motor for a timepiece can be achieved.

[0029]

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a perspective view of a timepiece motor according to the present invention. FIG. 1 is a plan view showing a schematic structure of a step motor for a timepiece, particularly a two-pole step motor, showing a first embodiment of the present invention, and is an exploded plan view of a coil core and a completed yoke. Hereinafter, description will be made with reference to FIG.

In an analog electronic timepiece, a timepiece step motor is intermittently driven in accordance with a reference signal generated by a quartz oscillator or the like, and the movement of the step motor is transmitted to a hand through a gear train mechanism to transmit the time. Displaying.

[Explanation of First Embodiment] A two-pole type stepping motor has a rotor 11 composed of a rotor shaft 11b having a rotation axis perpendicular to the plane of FIG. 1 and a rotor magnet 11a, and a rotor 11 installed. And has a completed yoke 9 and a coil core 1 made of a material having a high magnetic permeability and having an exciting coil 3 wound therearound.

The completed yoke 9 and the coil core 1 have a first screw hole 5 and a second screw hole 7, respectively, are overlapped so that the screw holes coincide with each other, and are fastened and fixed by screws (not shown). Then, the completed yoke 9 and the coil core 1 are magnetically connected to form a magnetic circuit.

The completed yoke 9 includes a first yoke component 21 made of a material having a high magnetic permeability and a second yoke component 21 made of a material having a high magnetic permeability.
A first yoke component 21 having a yoke component 23 and a connecting portion 25 made of a material having a low magnetic permeability or a non-magnetic material.
And the second yoke component 23 are connected via the connecting portion 25.

The rotor magnet 11a is made of a ferromagnetic material, and is magnetized in two poles in a direction perpendicular to the rotation axis. The rotor magnet 11a has a disk shape having a shaft hole for fitting the rotor shaft 11b at the center. It has become. Although not shown, a holding torque setting means for setting an initial phase angle and a holding torque is provided on the inner periphery of the rotor hole 13.

The first yoke component 21, the second yoke component 23, and the material having high magnetic permeability for the coil core 1 include, for example, pc permalloy and 42Ni permalloy. As a material, for example, Ni
Cr is used, and the completed yoke 9 and the coil core 1 using these are magnetically annealed to be components of a step motor. The material of the rotor magnet 11a is, for example, SmCo.

Further, the rotor 11 has a rotor hole 13
Are supported by bearings (not shown) at both ends of the rotor shaft 11b so as to be located at the center of the rotor shaft 11b. The rotor shaft 11b has a gear (not shown), and the rotational movement of the rotor 11 is used as a pointer through the gear. It is configured to communicate.

In the first embodiment, a step 35 is provided around the first screw hole 5 and the second screw hole 7 of the completed yoke 9. The thickness of the step portion 35 is
The thickness of the completed yoke 9 is set to 0.25 mm, which is half the thickness of 0.5 mm.

The coil core 1 and the first yoke component 2
1 has a first contact side surface 27 between the coil core side surface and the first yoke component side surface, and has a coil core side surface and a second contact surface between the coil core 1 and the second yoke component 23. And a second contact side surface 29 with the side surface of the yoke component. The first contact side 27 is on the straight line of the first straight line 31 passing through the center of the first screw hole 5, and the second contact side 29 is located on the second straight line passing through the center of the second screw hole 7. It is configured to be on the straight line 33.

Then, the coil core 1 is placed on the step portion 35 of the completed yoke 9 and is positioned by being superimposed on the first screw hole 5 and the second screw hole 7, respectively, and tightened and fixed by screws. At the first contact side surface 27 and the second contact side surface 29, the coil core 1 and the completed yoke 9 are brought into close contact with the coil core side and the completed yoke side without any gap, and are magnetically connected. Is composed.

In the timepiece stepping motor having the above-described structure, the driving voltage is applied to rotate the rotor 11 counterclockwise by 180 degrees (one step at a time), and the power consumption is reduced per unit time. It is expressed as the product of the amount of current flowing through the coil 3 of the step motor and the applied battery voltage. To reduce power consumption, it is necessary to reduce the amount of current while satisfying the required driving characteristics. Since the one-step motion of the motor is the same as that described in the related art, the description is omitted here.

Next, the direction in which the screw is tightened and the direction in which the moment is generated will be described with reference to FIG. Coil core 1
In order to obtain a magnetic connection between the coil yoke 9 and the completed yoke 9, the stepped portion 35 (not shown in FIG. 2) of the completed yoke 9
, And a screw (not shown) is inserted into the first screw hole 5 and tightened with the screw.
, A friction torque 37 generates a moment force 39 for rotating the coil core 1 clockwise around the first screw hole 5.

Here, since the first contact side surface 27 is on a straight line of the straight line 31 passing through the center of the first screw hole 5, the first contact side surface 27 is generated by the generated rotational moment force 39.
In this case, the coil core 1 can be brought into close contact with the side of the coil core and the side of the completed yoke without forming a gap with the completed yoke 9, and the magnetic resistance at the first contact side surface 27 can be reduced.

FIG. 3 is a view for explaining the direction and magnitude of the moment force acting on the contact side surface. A first screw hole 5 and a straight line 31 passing through the center of the first screw hole 5
And the moment 39 acting on the contact side surface 45 between the side surface of the completed yoke 9 and the side surface of the coil core of the coil core 1 will be described.

Since the moment force 39 is a tangential component of a circle centered on the first screw hole 5, the value of the moment force 39 is M, and the contact side surface 45 and the first screw hole 5
Is perpendicular to the contact side surface 45 due to the action of the moment force 39.

As can be seen from this equation, the moment force 39 is maximized when θ = 0, that is, when cos θ = 1, so that θ = 0 should be satisfied in order for the contact side surface 45 to be in close contact efficiently. Desirably, the contact side surface 45 is desirably on the straight line 31 passing through the center of the screw hole 5.

Since the magnetic flux of the entire magnetic circuit can be expressed by Φ = N × I / Rm, if the adhesion on the contact side surface can be improved and the magnetic resistance Rm can be reduced, it is constant even if the current value I of the denominator is reduced. The amount of magnetic flux Φ can be obtained, the power consumption of the stepping motor can be reduced, and the power consumption of the entire timepiece can be kept low.

In the structure of an actual timepiece, a coil terminal sheet, a circuit board, a circuit support plate and the like are superimposed on the completed yoke 9 and the coil core 1 and screwed. Is transmitted as a rotational moment to the coil winding core 1 by the frictional force of each component member, and a desired effect can be obtained.

In order to obtain a magnetic connection between the coil core 1 and the completed yoke 9 on the second contact side surface 29,
This is the same as the description for obtaining the magnetic connection between the coil core 1 and the completed yoke 9 on the first contact side surface 27 described with reference to FIG.

That is, the coil core 1 is superimposed on the stepped portion of the completed yoke 9, and a screw (not shown) is inserted into the second screw hole 7 and tightened. A friction torque (not shown) is generated during the rotation, and a moment force (not shown) for rotating the coil core 1 clockwise around the second screw hole 7 is generated by the friction torque.

Since the second contact side surface 29 is on the straight line of the second straight line 33 passing through the center of the second screw hole 7, the coil core is formed on the second contact side surface 29 by the generated rotational moment force. No. 1 allows the side surface of the coil core and the side surface of the completed yoke to be in close contact with each other without forming a gap with the completed yoke 9, and the magnetic resistance at the second contact side surface 29 can be reduced.

The flow of magnetic flux in the embodiment of the present invention in which the side surface 1a of the coil core and the side surface 9a of the completed yoke 9a are closely contacted with no gap will be described with reference to FIG. By connecting the completed yoke 9 and the coil core 1 with the screws 41, the thickness direction is fixed in contact with the horizontal surface of the stepped portion 35, and the side directions are the first contact side surface 27 and the second contact side surface 29.
As a result, the side surface 1a of the coil core and the side surface 9a of the completed yoke come into close contact with no gap.

As a result, the magnetic flux 43 flows from the coil core 1 to the completed yoke 9 at the flat portion and the side portion, and as shown in FIG. 4, there is no leakage magnetic flux, no narrowing of the magnetic path, and a low magnetic resistance. Therefore, even if the current value is reduced, a desired constant magnetic flux amount can be secured, and low power consumption of the timepiece stepping motor can be achieved.

In order to reduce the magnetic resistance by bringing the completed yoke side surface 9a of the completed yoke 9 and the coil core side surface 1a of the coil core 1 into close contact with the first contact side surface 27 and the second contact side surface 29. First, the screw inserted into the first screw hole 5 may be started first, or the screw inserted into the second screw hole 7 may be started first, and the first screw hole 5 and the second screw hole If the tightening force is gradually increased in both directions, desired adhesion can be ensured, and magnetic resistance can be reduced, that is, power consumption can be reduced.

[Explanation of Second Embodiment] Next, a second embodiment of the present invention will be described with reference to FIG. In the second embodiment, the completed yoke side surface 9a of the completed yoke 9 and the coil core side surface 1a of the coil core 1 are tightly fixed with no gap only on the first contact side surface 27.

The two-pole step motor has a rotor 11 composed of a rotor shaft 11b and a rotor magnet 11a having a rotation axis perpendicular to the plane of the paper of FIG. 5, and a rotor hole 13 for installing the rotor 11. A completed yoke 9 and a coil core 1 made of a material having a high magnetic permeability and having an exciting coil 3 wound therearound.

The completed yoke 9 and the coil core 1 have a first screw hole 5 and a second screw hole 7, respectively, are overlapped so that the screw holes coincide with each other, and tightened and fixed by screws (not shown). Then, the completed yoke 9 and the coil core 1 are magnetically connected to form a magnetic circuit.

The completed yoke 9 includes a first yoke component 21 made of a material having a high magnetic permeability and a second yoke component 21 made of a material having a high magnetic permeability.
A first yoke component 21 having a yoke component 23 and a connecting portion 25 made of a material having a low magnetic permeability or a non-magnetic material.
And the second yoke component 23 are connected via the connecting portion 25.

The rotor magnet 11a is made of a ferromagnetic material, and is magnetized to two poles in a direction perpendicular to the rotation axis, and has a disk shape having a center hole into which the rotor shaft 11b is fitted. Although not shown, the rotor hole 1
3 has a holding torque setting means for setting an initial phase angle and a holding torque.

Further, the rotor 11 has a rotor hole 13
Are supported by bearings (not shown) at both ends of the rotor shaft 11b so as to be located at the center of the rotor shaft 11b. The rotor shaft 11b has a gear (not shown), and the rotor 11
Is transmitted to the pointer.

In the second embodiment, the first screw hole 5 and the second screw hole 7 in the completed yoke 9 are provided.
Is provided in the vicinity of. The first contact side surface 27 is provided between the side surface of the coil core of the coil core 1 and the side surface of the first yoke component of the first yoke component 21. First passing through the center of the screw hole 5
Are arranged on the straight line of the straight line 31 of FIG.

The stepped portion 35 of the completed yoke 9 has the coil core 1
Are superimposed, a screw is inserted into the first screw hole 5, and the screw is tightened, so that a friction torque is generated between the screw and the coil core 1, and the friction torque causes the coil core 1 to be centered on the screw hole. Moment force to rotate clockwise (Fig. 5
(Not shown) works.

Then, the coil core 1 is completed on the first contact side surface 27 by the rotational moment force generated because the first contact side surface 27 is on the straight line of the straight line 31 passing through the center of the first screw hole 5. The side surface of the coil core and the side surface of the completed yoke can be brought into close contact with each other without forming a gap with the yoke 9. Thereby, the first contact side 2
7 can be reduced, and low power consumption can be achieved.

Further, in the second embodiment shown in FIG. 5, the shapes of the completed yoke 9 and the coil core 1 can be reduced as compared with the first embodiment, and Space saving of the motor can be achieved.

The magnetic flux of the entire magnetic circuit is Φ = N × I
/ Rm, it is possible to improve the adhesiveness of one contact side surface and reduce the magnetic resistance Rm.
Even if the current value I of the denominator is reduced, a fixed amount of magnetic flux Φ can be obtained, the power consumption of the step motor can be reduced, and the power consumption of the entire timepiece can be kept low.

In the actual timepiece structure, a coil terminal sheet, a circuit board, a circuit support plate and the like are superimposed on the completed yoke 9 and the coil winding core 1 and screwed. Is transmitted as a rotational moment to the coil core by the frictional resistance of each component, and a sufficient effect can be obtained.

In the first embodiment and the second embodiment, the first contact side surface 27 and the second contact side surface 29 are constituted by straight lines. As long as it can be brought into contact with the side without any gap, it does not have to be a straight line, and even if it is a curve, the in-plane vertical component of the moment force generated by the torque due to screw tightening can be used as the pressing force. Reduction of resistance and power consumption can be achieved.

Further, in the first and second embodiments, the example in which the step 35 is formed in the completed yoke 9 has been described, but the step may be formed in the coil core 1. Further, a step may be provided on both the completed yoke 9 and the coil core 1.

[0068]

As described above, in the stepping motor for a timepiece of the present invention, the side surface of the coil core and the side surface of the completed yoke are in close contact with each other without any gap. Preferably, the side surface where the side surface of the coil core and the side surface of the completed yoke are in close contact is on a straight line passing through the center of the screw hole.

As a result, the magnetic flux does not concentrate due to the narrowing of the magnetic path in the prior art, and the present invention can reduce the magnetic resistance in the magnetic circuit. Therefore,
The timepiece stepping motor of the present invention can reduce the magnetic resistance of the magnetic circuit of the stepping motor, thereby reducing the power consumption by 5 to 40% as compared with the prior art.

[Brief description of the drawings]

FIG. 1 is a plan view showing a step motor for a timepiece according to a first embodiment of the present invention, showing a state where a completed yoke and a coil core are disassembled.

FIG. 2 is a plan view showing the timepiece step motor according to the first embodiment of the present invention, showing a state where a completed yoke and a coil core are connected.

FIG. 3 is a view illustrating a moment force acting on a contact side surface of the timepiece step motor according to the embodiment of the present invention.

FIG. 4 is a view showing a flow of magnetic flux on a side surface of a completed yoke and a side surface of a coil core of the timepiece stepping motor according to the embodiment of the present invention.

FIG. 5 is a plan view showing a timepiece step motor according to a second embodiment of the present invention, showing a state where a completed yoke and a coil core are connected.

FIG. 6 is a plan view showing a structure of a conventional step motor for a timepiece.

FIG. 7 is a view showing a flow of a magnetic flux on a side surface of a step portion of a conventional step motor for a timepiece.

[Explanation of symbols]

1: Coil core 1a: Coil core side surface 3: Coil 5: First screw hole 7:
Second screw hole 9: Completed yoke 9a: Completed yoke side surface 11: Rotor 11a: Rotor magnet 11b: Rotor shaft 13: Rotor hole 15: Direction of magnetic field 17: Initial phase angle
19: Direction of magnetic pole 21: First yoke component 23: Second yoke component 25: Connecting portion 27: First contact side surface 29: Second contact side surface 31: First straight line 33: Second straight line 35 ： Step 3
7: Screw tightening torque 39: Rotating moment force 41: Screw
43: Magnetic flux

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) H02K 37/16 H02K 37/16 X

Claims (2)

[Claims] 1. A rotor comprising a rotor magnet and a rotor shaft, a completed yoke provided with a screw hole and a rotor hole for installing the rotor, and a coil core having a screw hole and wound with a coil. A time step motor for providing a stepped portion on the completed yoke or the coil core, and connecting the completed yoke and the coil core through the screw hole at the stepped portion. A step motor for a timepiece, wherein a side surface of a coil core and a side surface of a completed yoke of the completed yoke are in close contact with each other. 2. The stepping motor for a timepiece according to claim 1, wherein a side surface at which the side surface of the coil core and the side surface of the completed yoke are in close contact is on a straight line passing through the center of the screw hole.