JP7410760B2 - Stepping motor control device, movement, clock and stepping motor control method - Google Patents

Description

The present invention relates to a stepping motor control device, a movement, a timepiece, and a stepping motor control method.

Conventionally, in the technology of driving a stepping motor included in a watch, there has been a technology of rotating a rotor by exciting a stator with two coils in order to stably perform high-speed rotation (for example, as described in Patent Document 1). reference).

Japanese Patent Application Publication No. 2020-10570

With the techniques described above, magnetic flux may remain in the stator after the rotor has rotated. The magnetic flux remaining in the stator cancels out the magnetic flux necessary for rotation of the rotor, resulting in an unstable operation when starting the drive. Such a problem becomes a problem especially when rotating at high speed.

The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a stepping motor control device, a movement, a timepiece, and a stepping motor control method that can stably drive a rotor.

A stepping motor control device according to one aspect of the present invention includes a rotor that is magnetized with at least two poles, an N pole and an S pole, and that rotates a pointer, and a stator that provides a magnetic flux that generates a rotational force to the rotor. , driving a stepping motor including a first coil that supplies magnetic flux to a first end of both ends of the stator, and a second coil that supplies magnetic flux to a second end that is different from the first end of both ends of the stator. A stepping motor control device comprising: a drive pulse generation circuit that outputs a drive pulse that rotates the rotor by exciting the first coil and the second coil; a degaussing pulse generation circuit that outputs a degaussing pulse that reduces magnetic flux, the degaussing pulse being a two-phase excitation pulse that generates a torque that maintains the rotation angle of the rotor in a direction that matches the resting angle of the rotor. It is .

In the stepping motor control device according to one aspect of the present invention, the drive pulse is a pulse that rotates the rotor by a reference rotation angle corresponding to the number of poles, and the degaussing pulse generation circuit is a pulse that rotates the rotor by a reference rotation angle corresponding to the number of poles. After the application of the drive pulse is finished, a degaussing pulse is output after the rotor rotates so that the magnetic pole axis of the rotor and the magnetic pole axis of the excited stator pass at least once through a coincident position.

In the stepping motor control device according to one aspect of the present invention, the polarity of the degaussing pulse is one of the plurality of drive pulses applied when the rotor rotates by the reference rotation angle. It is the opposite of polarity.

In the stepping motor control device according to one aspect of the present invention, the polarity of the degaussing pulse is determined by the driving pulse applied last among the plurality of driving pulses applied when the rotor rotates by the reference rotation angle. The polarity of the pulse is opposite.

In the stepping motor control device according to one aspect of the present invention, the polarity of the degaussing pulse is determined by the drive pulse having the largest energy among the plurality of drive pulses applied when the rotor rotates by the reference rotation angle. The polarity is opposite to that of .

In the stepping motor control device according to one aspect of the present invention, the degaussing pulse is applied after the first drive pulse among the plurality of drive pulses applied when the rotor rotates by the reference rotation angle. , is applied after at least 5 ms have elapsed.

In the stepping motor control device according to one aspect of the present invention, the degaussing pulse is applied after the plurality of drive pulses applied when the rotor rotates by the reference rotation angle are continuously applied a plurality of times. It is applied after the last said drive pulse is applied.

In the stepping motor control device according to one aspect of the present invention, the degaussing pulse is applied between the successively applied drive pulses when the polarities of the successively applied drive pulses are different from each other. Ru.

In the stepping motor control device according to one aspect of the present invention, the degaussing pulse is configured such that the direction of the holding torque generated in the stator due to the application of the drive pulse and the direction of the magnetic pole axis of the rotor at the rest position of the rotor are determined. It is applied when the directions are different from each other.

In the stepping motor control device according to one aspect of the present invention, the degaussing pulse is a two-phase excitation pulse that generates a torque that maintains the rotation angle of the rotor in a direction that coincides with the rest angle of the rotor.

A movement according to one aspect of the present invention includes the above-described stepping motor control device and the stepping motor.

A timepiece according to one aspect of the present invention includes the movement described above.

A stepping motor control method according to one aspect of the present invention includes a rotor that is magnetized with at least two poles, an N pole and an S pole, and that rotates a pointer, and a stator that provides a magnetic flux that generates a rotational force to the rotor. , a stepping motor comprising: a first coil that supplies magnetic flux to a first end of both ends of the stator; and a second coil that supplies magnetic flux to a second end that is different from the first end of both ends of the stator. A stepping motor control method for driving a stepping motor, the method comprising: outputting a driving pulse that rotates the rotor by exciting the first coil and the second coil; and reducing residual magnetic flux generated when the driving pulse is applied. A demagnetizing pulse is output, and the demagnetizing pulse is a two-phase excitation pulse that generates a torque that maintains the rotation angle of the rotor in a direction that coincides with the rest angle of the rotor .

According to the present invention, the rotor can be driven stably.

FIG. 1 is a block diagram showing an example of a functional configuration of an analog electronic timepiece according to an embodiment. FIG. 1 is a schematic diagram of a stepping motor according to an embodiment. 3 is a time chart of control processing of an analog electronic watch when a degaussing pulse is not applied. FIG. 3 is an operation diagram of the stepping motor when no degaussing pulse is applied. 3 is a time chart of control processing of an analog electronic watch when applying a degaussing pulse. FIG. 3 is an operation diagram of the stepping motor when applying a demagnetizing pulse. FIG. 7 is an operation diagram when the rotor rotates due to an impact when no degaussing pulse is applied. FIG. 7 is an operation diagram when the rotor rotates due to an impact when applying a demagnetizing pulse. It is a time chart of control processing of an analog electronic timepiece according to a modification of the embodiment.

[Embodiment]
Embodiments of the present invention will be described below with reference to the drawings.

[Configuration of analog electronic clock 1]
FIG. 1 is a block diagram showing an analog electronic timepiece 1 according to an embodiment.
As shown in FIG. 1, the analog electronic watch 1 includes an oscillation circuit 101, a frequency dividing circuit 102, a control circuit 103, a motor drive circuit 104, a drive pulse generation circuit 121, a degaussing pulse generation circuit 122, and a stepping circuit. It includes a motor 105, a wheel train (not shown), and an analog display section 106.

Oscillation circuit 101 generates a signal at a predetermined frequency.
The frequency dividing circuit 102 divides the frequency of the signal generated by the oscillation circuit 101 to generate a clock signal that serves as a reference for timekeeping.
The control circuit 103 controls each electronic circuit element constituting the analog electronic timepiece 1 and controls pulse signals for driving the motor rotation.

The drive pulse generation circuit 121 outputs a drive pulse for rotationally driving the stepping motor 105 based on the control signal output from the control circuit 103.
The degaussing pulse generation circuit 122 outputs a degaussing pulse that reduces residual magnetic flux generated when the drive pulse generation circuit 121 applies a drive pulse for driving the motor rotation.
The motor drive circuit 104 drives the stepping motor 105 based on the drive pulse output from the drive pulse generation circuit 121 and the degaussing pulse output from the degaussing pulse generation circuit 122. Note that in this application, the drive pulse and the degaussing pulse may be referred to as pulse signals.

The stepping motor 105 is rotationally driven by a pulse signal for driving the motor rotation outputted from the drive pulse generation circuit 121.
The oscillation circuit 101, the frequency dividing circuit 102, the control circuit 103, the drive pulse generation circuit 121, the degaussing pulse generation circuit 122, and the motor drive circuit 104 constitute a control section (stepping motor control device) 112 of the analog electronic timepiece 1. .

A wheel train (not shown) is rotationally driven by a stepping motor 105.
The analog display section 106 includes an hour hand 107, a minute hand 108, and a second hand 109 (hereinafter referred to as hands when the hour hand 107, minute hand 108, and second hand 109 are not distinguished from each other) that are rotationally driven by the gear train, and a date display. It has a calendar display section 110 and the like.

Further, the analog electronic watch 1 includes a watch case 113. An analog display section 106 is provided on the outer surface of the watch case 113. The analog display section 106 is a dial with a scale engraved on it.
Further, inside the watch case 113, a watch movement 114 including the above-mentioned wheel train is disposed. The movement 114 is a mechanical mechanism for driving each part of the analog electronic timepiece 1. The timepiece movement 114 includes a control section 112 and a stepping motor 105.

FIG. 2 is a schematic diagram of the stepping motor 105 according to the embodiment.
As shown in FIG. 2, the stepping motor 105 has a stator 20 having a rotor housing hole 25, and has magnetic polarity by being magnetized into two poles in the radial direction. A rotor 30 is provided. The stepping motor 105 operates for each unit step and rotates the pointer.

The stator 20 includes a stator body 21, a first magnetic core (first end) 40A magnetically connected to the stator body 21, a second magnetic core (second end) 40B, and a first magnetic core 40A wound around the stator body 21. It includes a first coil 50A and a second coil 50B wound around a second magnetic core 40B.

The stator main body 21 is formed of a plate material using a high magnetic permeability material such as permalloy. The stator main body 21 has a T-shaped first yoke 22, a pair of second yokes 23, and a second yoke 24, and is formed in an H-shape in plan view. That is, the T-shaped first yoke 22 includes a straight portion 22a extending in a predetermined first direction, and a pair of tension members extending from one end of the straight portion 22a to both sides in a second direction perpendicular to the first direction. It includes a projecting portion 22b and a projecting portion 22c. The second yoke 23 is provided to extend from the other end of the straight portion 22a to the same side as the overhang portion 22b, and the second yoke 24 is provided to extend from the other end of the straight portion 22a. It is provided so as to project on the same side as the projecting portion 22c. Due to the configuration of the first yoke 22, the second yoke 23, and the second yoke 24, the stator main body 21 is formed into an H shape in plan view. Note that the first yoke 22, the second yoke 23, and the second yoke 24 are integrally formed.

At the intersection of the first yoke 22, the second yoke 23, and the second yoke 24 of the stator main body 21, the circular rotor housing hole 25 described above is formed. A pair of notches 25a are formed on the inner circumferential surface of the rotor accommodation hole 25 so as to be lined up in the second direction and face each other. The cutout portion 25a is cut out in an arc shape. These notches 25a are configured as positioning parts for determining the stop position of the rotor 30. The rotor 30 has the lowest potential energy and stably stops when its magnetic pole axis is at a position orthogonal to the line segment connecting the pair of notches 25a, that is, when the magnetic pole axis is at a position along the first direction. Hereinafter, the stopping position of the rotor 30 (the position shown in FIG. 2) when the magnetic pole axis of the rotor 30 is along the first direction and the N pole of the rotor 30 faces the first yoke 22 side will be referred to as a first stopping position. Further, the stopping position of the rotor 30 when the magnetic pole axis of the rotor 30 is along the first direction and the S pole of the rotor 30 faces the first yoke 22 side is referred to as a second stopping position.

Further, around the rotor accommodation hole 25 in the stator body 21, three notches 26 are formed which are cut out from the outer peripheral edge of the stator body 21 toward the rotor accommodation hole 25 in a plan view. Each notch 26 has a corner where the first yoke 22 and the second yoke 23 connect, a corner where the first yoke 22 and the second yoke 24 connect, and a corner where the second yoke 23 and the second yoke 24 connect. is formed with the connecting part. Each cutout portion 26 is cut out in an arc shape.

The circumference of the rotor accommodation hole 25 in the stator body 21 is locally narrowed by each notch 26 (hereinafter, the locally narrowed portion may be referred to as a narrow portion). The narrow portion is more susceptible to magnetic saturation than other portions of the stator body 21, and due to the magnetic saturation of the narrow portion, the stator body 21 is magnetically divided into three parts around the rotor housing hole 25. The stator body 21 includes a first magnetic pole portion 20A disposed around the rotor 30 at a position corresponding to the second yoke 23, and a second magnetic pole section 20A disposed around the rotor 30 at a position corresponding to the second yoke 24. It has a magnetic pole part 20B and a third magnetic pole part 20C disposed around the rotor 30 at a position corresponding to the straight part 22a of the first yoke 22.

Here, each part of the rotor 30 is divided into 30A to 30D by the magnetic pole axis A and the perpendicular straight line B. A portion of the first magnetic pole portion 20A extending along the rotor accommodation hole 25 from the notch 26 formed at the portion where the second yoke 23 and the second yoke 24 connect to the notch 25a formed in the second yoke 23 is disposed to face the portion 30A of the rotor 30 located at the first stop position (the portion 30C of the rotor 30 located at the second stop position). A portion of the second magnetic pole portion 20B extending along the rotor accommodation hole 25 from the notch 26 formed at the portion where the second yoke 23 and the second yoke 24 connect to the notch 25a formed in the second yoke 24. is disposed opposite to a portion 30B of the rotor 30 located at the first stop position (a portion 30D of the rotor 30 located at the second stop position).
The third magnetic pole portion 20C is arranged to face the north pole of the rotor 30 located at the first stop position (the south pole of the rotor 30 located at the second stop position).

Each of the first magnetic core 40A and the second magnetic core 40B is made of a high magnetic permeability material such as permalloy. The first magnetic core 40A is magnetically connected to the tip of the overhang 22c and the tip of the second yoke 24. The second magnetic core 40B is magnetically connected to the tip of the overhang 22b and the tip of the second yoke 23. Both ends of each of the first magnetic core 40A and the second magnetic core 40B are connected to the stator main body 21 by, for example, screws.

The first coil 50A is wound around the first magnetic core 40A, and is magnetically coupled to the second magnetic pole part 20B and the third magnetic pole part 20C. The first coil 50A has a first terminal 50Aa and a second terminal 50Ab. The first coil 50A is configured such that when a current flows from the first terminal 50Aa to the second terminal 50Ab, a magnetic field is generated in the first coil 50A from the overhang 22c side to the second yoke 24 side. It is wrapped.

The second coil 50B is wound around the second magnetic core 40B, and is magnetically coupled to the first magnetic pole part 20A and the third magnetic pole part 20C. The second coil 50B has a first terminal 50Ba and a second terminal 50Bb. The second terminal 50Bb of the second coil 50B is provided to have the same potential as the second terminal 50Ab of the first coil 50A. The second coil 50B is configured such that when a current flows from the first terminal 50Ba to the second terminal 50Bb, a magnetic field is generated in the second coil 50B from the second yoke 23 side toward the overhang 22b side. It is wrapped.

The wire diameter of the first coil 50A is the same as the wire diameter of the second coil 50B. Further, the number of windings of the first coil 50A is the same as the number of windings of the second coil 50B. Terminals of the first coil 50A and the second coil 50B are connected to the drive pulse generation circuit 121. In the following description, the potential of the first terminal 50Aa of the first coil 50A is set as out1, the potential of the second terminal 50Ab of the first coil 50A is set as out2, the potential of the first terminal 50Ba of the second coil 50B is set as out3, The potential of the second terminal 50Bb of the second coil 50B is set to out4.

In the stator 20 configured in this manner, when magnetic flux is generated from the first coil 50A or the second coil 50B, the magnetic flux flows along the stator main body 21 and each of the first magnetic core 40A and the second magnetic core 40B. The polarity of the first magnetic pole section 20A, second magnetic pole section 20B, and third magnetic pole section 20C described above is switched depending on the energization state of the first coil 50A or the second coil 50B.

That is, the stepping motor 105 includes a rotor 30, a stator 20, a first coil 50A, and a second coil 50B. Stator 20 provides magnetic flux to rotor 30 that generates rotational force. The rotor 30 is magnetized to have at least two poles, a north pole and a south pole, and rotates the pointer. The first coil 50A supplies magnetic flux to the first magnetic core 40A at both ends of the stator 20. The second coil 50B supplies magnetic flux to the second magnetic core 40B at both ends of the stator 20.
The drive pulse output by the drive pulse generation circuit 121 excites the first coil 50A and the second coil 50B, thereby driving the rotor 30 by a reference rotation angle corresponding to the number of poles.

Note that the reference rotation angle according to the number of poles herein may be an angle obtained by dividing the angle of one rotation of the rotor 30 by the number of poles on which the rotor is magnetized. For example, when the rotor 30 has two poles, the reference rotation angle according to the number of poles is an angle obtained by dividing the angle of one rotation by 2 (180°). Further, when the rotor 30 has four poles, the reference rotation angle corresponding to the number of poles is an angle (90°) obtained by dividing the angle of one rotation by four.

[Example of operation of stepping motor 105 when no degaussing pulse is applied]
The operation of the stepping motor 105 when no degaussing pulse is applied will be described with reference to FIGS. 3 and 4.
FIG. 3 is a time chart of control processing of the analog electronic watch when no degaussing pulse is applied. FIG. 3 shows temporal changes in the potentials of out1, out2, out3, and out4. A state in which a predetermined potential V is applied is described as H, and a state in which the predetermined potential V is not applied is described as L.
FIG. 4 is an operational diagram of the stepping motor when no degaussing pulse is applied. The figure shows the direction of the magnetic flux generated by the drive pulse or the demagnetizing pulse and the rotation angle of the rotor.

The control unit 112 of the present embodiment outputs a predetermined pulse group PG to the first coil 50A and the second coil 50B, thereby controlling the rotor 30 in each unit step (180°) according to each of the pulse groups PG. do. The control unit 112 of the analog electronic timepiece 1 moves the hands by repeatedly controlling the application of the pulse group PG to the first coil 50A and the second coil 50B.

The above-mentioned pulse group PG is composed of pulses corresponding to the respective excitation states of the first magnetic pole part 20A, the second magnetic pole part 20B, and the third magnetic pole part 20C. Specifically, the pulses forming the pulse group PG include a drive pulse outputted by the drive pulse generation circuit 121 and a degaussing pulse Pe outputted by the degaussing pulse generation circuit 122. The drive pulse generation circuit 121 rotates the rotor 30 by one step by outputting the first pulse P1 and the second pulse P2, which are drive pulses, as a first pulse group PG1.
Note that the pulses forming the pulse group PG are not limited to this example, and may be formed by including other pulses.

At the start of the time chart shown in FIG. 3 (before time t11; initial state), each magnetic pole part (first magnetic pole part 20A, second magnetic pole part 20B, and third magnetic pole part 20C) is not excited, and the rotor 30 is located at the first stop position (FIG. 4(A)).
The control unit 112 applies the first pulse group PG1 (PG) to the first coil 50A and the second coil 50B to rotate the rotor 30 in unit steps from the first stop position to the second stop position.

At time t11, the drive pulse generation circuit 121 applies a predetermined voltage V to the first terminal 50Aa of the first coil 50A as the first pulse P1 of the first pulse group PG1. As a result, a current flows through the first coil 50A from the first terminal 50Aa to the second terminal 50Ab. Further, the second coil 50B is in a non-energized state.

As shown in FIG. 4(B), by applying the first pulse P1 to the first coil 50A, the first magnetic pole part 20A and the third magnetic pole part 20C, which are arranged to face the N pole of the rotor 30, It is excited to become a pole. Further, the second magnetic pole portion 20B, which is disposed opposite to the S pole of the rotor 30, is excited to become the N pole. As a result, the rotor 30 rotates by 1/4 step (for example, about 45 degrees).

At time t12, the drive pulse generation circuit 121 stops outputting the first pulse P1, and applies a predetermined voltage V to the first terminal 50Ba of the second coil 50B as the second pulse P2 of the first pulse group PG1. . As a result, a current flows through the second coil 50B from the first terminal 50Ba to the second terminal 50Bb. Further, the first coil 50A is in a non-energized state.

As shown in FIG. 4C, by applying the second pulse P2 to the second coil 50B, the first magnetic pole portion 20A is excited to become the S pole. Moreover, the second magnetic pole part 20B and the third magnetic pole part 20C are excited to become N poles. As a result, the rotor 30 moves in 1/2 steps such that its north pole is separated from the first magnetic pole part 20A and is attracted to the second magnetic pole part 20B, and the south pole is attracted to the third magnetic pole part 20C. (for example, about 90 degrees) in a predetermined rotation direction.

At time t13, the drive pulse generation circuit 121 stops outputting the second pulse P2. That is, at time t13, since neither the first pulse P1 nor the second pulse P2 is output, both the first coil 50A and the second coil 50B are in a non-energized state.

As shown in FIG. 4(D), the magnetic flux generated by the second pulse P2 may remain as residual magnetic flux in the first magnetic pole part 20A, the second magnetic pole part 20B, and the third magnetic pole part 20C. In this example, since the control unit 112 does not output the degaussing pulse Pe, the magnetic flux generated by the drive pulse P2 remains in the first magnetic pole part 20A, the second magnetic pole part 20B, and the third magnetic pole part 20C.
The rotor 30 is stabilized at the second stop position where the S pole faces the third magnetic pole portion 20C, but due to the residual magnetic flux and the rotor 30 attracting each other, the rotor 30 stops at a position different from the second stop position.

From time t14 to time t17, the control unit 112 moves the rotor 30 from the second stop position to the first stop position by outputting the third pulse P3 and fourth pulse P4, which are drive pulses, as the second pulse group PG2. Rotate in unit steps toward the target. Further, from time t17 to time t20, the control unit 112 moves the rotor 30 from the first stop position to the second stop by outputting the first pulse P1 and the second pulse P2, which are drive pulses, as the first pulse group PG1. Rotate unit steps toward position.

[Example of operation of stepping motor 105 when applying demagnetizing pulse]
The operation of the stepping motor 105 when applying a degaussing pulse will be described with reference to FIGS. 5 and 6.
FIG. 5 is a time chart of control processing of the analog electronic watch when applying a degaussing pulse. FIG. 5 shows temporal changes in the potentials of out1, out2, out3, and out4. A state in which a predetermined potential V is applied is described as H, and a state in which the predetermined potential V is not applied is described as L.
FIG. 6 is an operational diagram of the stepping motor when applying a degaussing pulse. The figure shows the direction of the magnetic flux generated by the drive pulse or the demagnetizing pulse and the rotation angle of the rotor. Operations similar to those in FIGS. 3 and 4 may be given the same reference numerals and descriptions thereof may be omitted.
The operations up to time t13 in FIG. 5 and the operations in FIGS. 6(A), 6(B), and 6(C) in FIG. 6 are the same as those described with reference to FIGS. 3 and 4. be.

As explained in FIG. 3, when the drive pulse generation circuit 121 outputs the second pulse P2 from time t12 to time t13, as explained in FIG. A current flows from the terminal 50Ba to the second terminal 50Bb. When a current flows from the first terminal 50Ba to the second terminal 50Bb, the first magnetic pole part 20A is excited to become an S pole, and the second magnetic pole part 20B and the third magnetic pole part 20C are excited to become an N pole.
At this time, the magnetic pole axis of the rotor 30 moves from the rotational position of the magnetic pole axis A shown in FIG. 6(B) to the rotational position of the magnetic pole axis A shown in FIG. 6(C) by only 1/2 step (for example, about 90° ), rotationally driven.

A degaussing pulse Pe is applied from time t21 to time t22. The degaussing pulse Pe is applied, for example, after at least 5 ms has elapsed from time t11.
The demagnetizing pulse generation circuit 122 outputs the demagnetizing pulse Pe after the rotor 30 rotates and the magnetic pole axis A of the rotor 30 and the magnetic pole axis of the excited stator 20 pass at least once through a coincident position. Further, the demagnetizing pulse generating circuit 122 generates a demagnetizing pulse after the driving pulse generating circuit 121 finishes applying the driving pulse, that is, after time t13 when the driving pulse generating circuit 121 finishes outputting the second pulse P2 in FIG. Output Pe.

The polarity of the demagnetizing pulse Pe output by the demagnetizing pulse generation circuit 122 is determined by the polarity of the plurality of drive pulses (in the first pulse group PG1, the The polarity is opposite to that of any one of the first pulse P1 and the second pulse P2). For example, the polarity of the degaussing pulse Pe is opposite to the polarity of the last drive pulse applied among the plurality of drive pulses applied when the rotor 30 rotates by the reference rotation angle. In this case, since the last drive pulse applied before time t21 is the second pulse P2, a pulse with a polarity opposite to that of the second pulse P2 is output as the degaussing pulse Pe.

Note that the degaussing pulse generation circuit 122 outputs, as a degaussing pulse Pe, a pulse whose polarity is opposite to that of the drive pulse with the largest energy among the plurality of drive pulses applied when the rotor 30 rotates by the reference rotation angle. You may. In this case, since the energy of the second pulse P2 is greater than that of the first pulse P1, a pulse with polarity opposite to that of the second pulse P2 is output as the demagnetizing pulse Pe.

The degaussing pulse generation circuit 122 outputs a pulse having a polarity corresponding to the polarity of the drive pulse outputted by the drive pulse generation circuit 121 as a degaussing pulse. The degaussing pulse generation circuit 122 may be configured to output a pulse having an energy level corresponding to the energy level of the drive pulse outputted by the drive pulse generation circuit 121 as the degaussing pulse.

As shown in FIG. 6(D), by applying the degaussing pulse Pe to the second coil 50B, a magnetic flux is generated in the first magnetic pole portion 20A to form a north pole. Further, magnetic flux is generated in the second magnetic pole portion 20B and the third magnetic pole portion 20C to form an S pole. As a result, the magnetic flux generated by the degaussing pulse Pe reduces the residual magnetic flux remaining in the stator 20 or cancels the residual magnetic flux remaining in the stator 20.

At time t22, the degaussing pulse generation circuit 122 stops outputting the degaussing pulse Pe, and as shown in FIG. It stably stops at the second stop position, which is the opposite position.

[Operation when rotor 30 rotates due to impact]
The operation when the rotor 30 rotates due to an external impact will be described with reference to FIGS. 7 and 8. FIG. 7 is an example of the operation of the stepping motor 105 when the degaussing pulse Pe is not applied, and FIG. 8 is an example of the operation of the stepping motor 105 when the degaussing pulse Pe is applied.

[Operation when rotor 30 rotates due to impact when no degaussing pulse is applied]
FIG. 7 is a diagram showing the operation when the rotor 30 rotates due to an external impact between time t13 and time t14 in the example shown in FIG.
FIG. 7A is a diagram showing the state after the output of the second pulse P2 is stopped at time t13. As shown in the figure, the magnetic flux generated by the drive pulse P2 remains in the first magnetic pole part 20A, the second magnetic pole part 20B, and the third magnetic pole part 20C. Since magnetic flux remains in the first magnetic pole part 20A, the second magnetic pole part 20B, and the third magnetic pole part 20C, the rotor 30 is stationary in a state shifted from the second stop position.

FIG. 7(B) is a diagram showing the state of the rotor 30 when the rotor 30 rotates due to an external impact between time t13 and time t14 in FIG. In this case, since the control unit 112 does not detect that the rotor 30 has rotated, it drives the rotor 30 using normal control.

FIG. 7C shows that at time t14 in FIG. 3, the drive pulse generation circuit 121 applies a predetermined voltage V to the second terminal 50Ab of the first coil 50A as the third pulse P3 of the second pulse group PG2. FIG. As a result, a current flows through the first coil 50A from the second terminal 50Ab to the first terminal 50Aa. Further, the second coil 50B is in a non-energized state.
By applying the third pulse P3 to the first coil 50A, the first magnetic pole part 20A and the third magnetic pole part 20C are excited to become N poles. Further, the second magnetic pole portion 20B is excited to become an S pole. As a result, the rotor 30 is reversed by one step (for example, about 180 degrees).

FIG. 7D shows that at time t15 in FIG. 3, the drive pulse generation circuit 121 applies a predetermined voltage V to the second terminal 50Bb of the second coil 50B as the fourth pulse P4 of the second pulse group PG2. FIG. As a result, a current flows through the second coil 50B from the second terminal 50Bb toward the first terminal 50Ba. Further, the first coil 50A is in a non-energized state.
By applying the fourth pulse P4 to the second coil 50B, the first magnetic pole portion 20A is excited to become the north pole. Moreover, the second magnetic pole part 20B and the third magnetic pole part 20C are excited to become S poles. As a result, the first magnetic pole part 20A, the second magnetic pole part 20B, and the third magnetic pole part 20C cannot attract the rotor 30 and cannot rotate the rotor 30.

FIG. 7E is a diagram when the drive pulse generation circuit 121 stops outputting the fourth pulse P4 at time t16 in FIG. As shown in the figure, the magnetic flux generated by the fourth pulse P4 remains, and the rotor 30 is at rest in a 180° reversed state.

FIG. 7F shows that at time t17 in FIG. 3, the drive pulse generation circuit 121 applies a predetermined voltage V to the first terminal 50Aa of the first coil 50A as the first pulse P1 of the first pulse group PG1. FIG. As a result, a current flows through the first coil 50A from the first terminal 50Aa to the second terminal 50Ab. Further, the second coil 50B is in a non-energized state.
By applying the first pulse P1 to the first coil 50A, the first magnetic pole part 20A and the third magnetic pole part 20C are excited to become the south pole. Further, the second magnetic pole portion 20B is excited to become a north pole. As a result, the rotor 30 is reversed by one step (for example, about 180 degrees).

FIG. 7G shows that at time t18 in FIG. 3, the drive pulse generation circuit 121 applies a predetermined voltage V to the first terminal 50Ba of the second coil 50B as the second pulse P2 of the first pulse group PG1. FIG. As a result, a current flows through the second coil 50B from the first terminal 50Ba to the second terminal 50Bb. Further, the first coil 50A is in a non-energized state.
By applying the second pulse P2 to the second coil 50B, the first magnetic pole portion 20A is excited to become the south pole. Moreover, the second magnetic pole part 20B and the third magnetic pole part 20C are excited to become N poles. As a result, the first magnetic pole part 20A, the second magnetic pole part 20B, and the third magnetic pole part 20C cannot attract the rotor 30 and cannot rotate the rotor 30.

FIG. 7(H) is a diagram when the drive pulse generation circuit 121 stops outputting the second pulse P2 at time t19 in FIG. As shown in the figure, the magnetic flux generated by the second pulse P2 remains, and the rotor 30 is at rest in a 180° reversed state.

As described with reference to FIG. 7, when residual magnetic flux is generated and the rotor 30 rotates due to external vibration, the rotor 30 will not rotate even if the drive pulse generation circuit 121 outputs a drive pulse. Unable to do so, it rotates in the opposite direction. In this embodiment, in order to suppress such a phenomenon, residual magnetic flux is reduced by applying a demagnetizing pulse Pe. By reducing the residual magnetic flux, even when the rotor 30 is rotated due to an external impact, the rotor 30 is again made to follow the drive pulse output from the drive pulse generation circuit 121.

[Operation when the rotor 30 rotates due to impact when applying a demagnetizing pulse]
FIG. 8 is a diagram showing the operation when the rotor 30 rotates due to an external impact between time t13 and time t14 in the example shown in FIG.
FIG. 8A is a diagram showing the state after the output of the second pulse P2 is stopped at time t13. As shown in the figure, the magnetic flux generated by the drive pulse P2 is reduced by the degaussing pulse Pe, so no magnetic flux remains in the first magnetic pole part 20A, the second magnetic pole part 20B, and the third magnetic pole part 20C. do not have. Further, the rotor 30 is stably stopped at the second stop position where the S pole faces the third magnetic pole portion 20C.

FIG. 8(B) is a diagram showing the state of the rotor 30 when the rotor 30 rotates due to an external impact between time t13 and time t14 in FIG. In this case, since the control unit 112 does not detect that the rotor 30 has rotated, it drives the rotor 30 using normal control.

FIG. 8C shows that at time t14 in FIG. 5, the drive pulse generation circuit 121 applies a predetermined voltage V to the second terminal 50Ab of the first coil 50A as the third pulse P3 of the second pulse group PG2. FIG. As a result, a current flows through the first coil 50A from the second terminal 50Ab to the first terminal 50Aa. Further, the second coil 50B is in a non-energized state.
By applying the third pulse P3 to the first coil 50A, the first magnetic pole part 20A and the third magnetic pole part 20C are excited to become N poles. Further, the second magnetic pole portion 20B is excited to become an S pole. As a result, the rotor 30 reverses to a rotation angle where the S pole attracts the first magnetic pole part 20A and the third magnetic pole part 20C, which are excited to the N pole.

FIG. 8D shows that at time t15 in FIG. 5, the drive pulse generation circuit 121 applies a predetermined voltage V to the second terminal 50Bb of the second coil 50B as the fourth pulse P4 of the second pulse group PG2. FIG. As a result, a current flows through the second coil 50B from the second terminal 50Bb toward the first terminal 50Ba. Further, the first coil 50A is in a non-energized state.
By applying the fourth pulse P4 to the second coil 50B, the first magnetic pole portion 20A is excited to become the north pole. Moreover, the second magnetic pole part 20B and the third magnetic pole part 20C are excited to become S poles. As a result, the polarity of the rotor 30 matches the polarity of the first magnetic pole part 20A, the second magnetic pole part 20B, and the third magnetic pole part 20C. That is, the first magnetic pole part 20A, the second magnetic pole part 20B, and the third magnetic pole part 20C can attract the rotor 30.

FIG. 8(E) is a diagram when the drive pulse generation circuit 121 stops outputting the fourth pulse P4 at time t16 in FIG. As shown in the figure, the magnetic flux generated by the fourth pulse P4 is canceled by the degaussing pulse Pe applied from time t23 to time t24. The rotor 30 is stationary in a state where the polarity matches the control of the drive pulse outputted by the drive pulse generation circuit 121. Since the rotor 30 has the same polarity as the drive pulse control output from the drive pulse generation circuit 121, the rotor 30 is normally driven after time t17.

FIG. 8F shows that at time t17 in FIG. 5, the drive pulse generation circuit 121 applies a predetermined voltage V to the first terminal 50Aa of the first coil 50A as the first pulse P1 of the first pulse group PG1. FIG. As a result, a current flows through the first coil 50A from the first terminal 50Aa to the second terminal 50Ab. Further, the second coil 50B is in a non-energized state.
By applying the first pulse P1 to the first coil 50A, the first magnetic pole part 20A and the third magnetic pole part 20C are excited to become the south pole. Further, the second magnetic pole portion 20B is excited to become a north pole. As a result, the rotor 30 rotates by 1/4 step (for example, about 45 degrees).

FIG. 8(G) shows that at time t18 in FIG. 5, the drive pulse generation circuit 121 applies a predetermined voltage V to the first terminal 50Ba of the second coil 50B as the second pulse P2 of the first pulse group PG1. FIG. As a result, a current flows through the second coil 50B from the first terminal 50Ba to the second terminal 50Bb. Further, the first coil 50A is in a non-energized state.
By applying the second pulse P2 to the second coil 50B, the first magnetic pole portion 20A is excited to become the south pole. Moreover, the second magnetic pole part 20B and the third magnetic pole part 20C are excited to become N poles. As a result, the rotor 30 rotates by 1/2 step (for example, about 90 degrees).

FIG. 8(H) is a diagram when the drive pulse generation circuit 121 stops outputting the second pulse P2 at time t19 in FIG. As shown in the figure, the magnetic flux generated by the second pulse P2 is canceled by the degaussing pulse Pe applied from time t25 to time t26 in FIG. The rotor 30 is stably stationary at the first stop position.

As described with reference to FIG. 8, when applying the degaussing pulse Pe, even if the rotor 30 rotates due to an external impact, the rotor 30 is driven again by the drive pulse output from the drive pulse generation circuit 121. It can be made to follow the pulse.

[Summary of embodiments]
According to the embodiment described above, the control unit 112 includes a drive pulse generation circuit 121 and a degaussing pulse generation circuit 122, and reduces the residual magnetic flux generated when a drive pulse is applied. Here, when the rotor 30 is driven in a state where residual magnetic flux remains, the rotor 30 may not follow the control of the control unit 112. In particular, if the rotor 30 rotates due to an external impact while the rotor 30 is stationary, the rotor 30 may reverse in an unintended direction contrary to the control of the control unit 112. be. According to this embodiment, since the residual magnetic flux is reduced by applying the degaussing pulse Pe, even if the rotor 30 is rotated due to an external impact while the rotor 30 is stationary, the The polarity of the rotor 30 can be made to match the polarity controlled by the control unit 112.
Therefore, according to this embodiment, the control unit 112 can stably drive the rotor 30.

Further, according to the embodiment described above, in the control unit 112, the degaussing pulse generation circuit 122 causes the magnetic pole axis of the rotor 30 to rotate after the drive pulse generation circuit 121 finishes applying the drive pulse. , after passing at least once a position where the magnetic pole axis of the excited stator 20 coincides with the magnetic pole axis, the demagnetizing pulse Pe is output. Therefore, according to the present embodiment, the control unit 112 can demagnetize the magnetic flux generated after the rotor 30 rotates by outputting the demagnetizing pulse Pe after the rotor 30 rotates.

Further, according to the embodiment described above, in the control unit 112, the polarity of the degaussing pulse Pe is determined by one of the plurality of drive pulses applied when the rotor 30 rotates by the reference rotation angle. It is the opposite of polarity. Therefore, according to the present embodiment, the control unit 112 does not apply a pulse with the same polarity as the drive pulse as the degaussing pulse Pe, so that malfunctions that would increase the degaussing pulse Pe can be prevented. I can do it.

Further, according to the embodiment described above, in the control unit 112, the polarity of the degaussing pulse Pe is determined by the drive pulse applied last among the plurality of drive pulses applied when the rotor 30 rotates by the reference rotation angle. The polarity of the pulse is opposite. That is, according to this embodiment, the control unit 112 can suppress residual magnetic flux generated by the last applied drive pulse.

Further, according to the embodiment described above, in the control unit 112, the polarity of the degaussing pulse Pe is determined by the drive pulse having the largest energy among the plurality of drive pulses applied when the rotor 30 rotates by the reference rotation angle. The polarity is opposite to that of . Therefore, according to the present embodiment, the control unit 112 does not apply a pulse with a polarity opposite to the polarity of the magnetic flux remaining as residual magnetic flux as the degaussing pulse Pe, so that the control unit 112 does not increase the degaussing pulse Pe. It is possible to prevent malfunctions.

Further, according to the embodiment described above, in the control unit 112, the polarity of the degaussing pulse Pe is determined by the first drive pulse among the plurality of drive pulses applied when the rotor 30 rotates by the reference rotation angle. is applied after at least 5 ms has elapsed. Therefore, according to this embodiment, it is possible to prevent malfunctions such as applying the degaussing pulse Pe while applying the driving pulse.

[Modification of embodiment]
FIG. 9 is a time chart of control processing of the analog electronic timepiece 1 according to a modification of the embodiment. A modification of the analog electronic timepiece 1 described above will be described with reference to the same figure.
FIG. 9 is a time chart of the control process of the analog electronic watch when applying the degaussing pulse Pe. FIG. 9 shows temporal changes in the potentials of out1, out2, out3, and out4. A state in which a predetermined potential V is applied is described as H, and a state in which the predetermined potential V is not applied is described as L.

In a modified example described with reference to FIG.
This is an example of a case where the degaussing pulse Pe is applied after the last drive pulse is applied when the drive pulse is continuously applied a plurality of times and then the drive is stopped.

At time t51, the control unit 112 starts driving the stepping motor 105. The control unit 112 rotates the rotor 30 by a reference rotation angle (for example, about 180°) by applying the pulse group PG1 from time t51 to time t54. At this time, the control unit 112 does not apply the degaussing pulse Pe.

The control unit 112 continuously drives the rotor 30. Specifically, the control unit 112 continuously applies the drive pulse multiple times after time t54. The control unit 112 does not apply the degaussing pulse Pe while being continuously driven.

At time t55, the control unit 112 applies the last pulse group PG2 in continuous driving. The control unit 112 rotates the rotor 30 by a reference rotation angle (for example, about 180°) by applying the pulse group PG2 from time t55 to time t60.

In this example, the degaussing pulse Pe is applied from time t58 to time t59. That is, the degaussing pulse generation circuit 122 applies the plurality of drive pulses applied when the rotor 30 rotates by the reference rotation angle after the last drive pulse is applied continuously a plurality of times. .

Note that continuous drive refers to high-speed drive in which the drive pulses output by the drive pulse generation circuit 121 are driven at a faster cycle than normal drive to measure time (for example, normal drive to drive the second hand 109 at 1-second intervals). It may be.

Here, the degaussing pulse Pe has a greater effect when applied at rest after the end of continuous driving than when applied during the continuously driven pulse group PG. be. That is, according to the modified example of the present embodiment, the control unit 112 applies the degaussing pulse Pe after continuously applying the drive pulse a plurality of times and after applying the last drive pulse. It is possible to prevent the degaussing pulse Pe from being output.
Furthermore, since it is possible to prevent the degaussing pulse Pe from being output at an unnecessary timing, the control unit 112 can prevent malfunctions. Furthermore, the control unit 112 can suppress power consumption.

Further, when driving the rotor 30 at high speed, the control unit 112 applies the demagnetizing pulse Pe after the last driving pulse is applied.
Therefore, according to the modification of the present embodiment, it is possible to prevent the degaussing pulse Pe from being output at an unnecessary timing during high-speed driving, so that the control unit 112 can prevent malfunctions. Furthermore, the control unit 112 can suppress power consumption.

Note that the control unit 112 may be configured to apply the degaussing pulse Pe if the next drive pulse has a different polarity after continuous driving. That is, in this case, the degaussing pulse Pe is applied between successively applied drive pulses when the polarities of the successively applied drive pulses are different from each other.
Here, the degaussing pulse Pe has a greater effect when the polarities of successively applied pulses are different from each other than when the polarities of the successively applied pulses are the same.
Therefore, according to the modification of the present embodiment, it is possible to prevent the degaussing pulse Pe from being output at an unnecessary timing, so that the control unit 112 can prevent malfunctions. Furthermore, the control unit 112 can suppress power consumption.

Furthermore, if the direction of the holding torque generated in the stator 20 is the same as the direction of the rotor's magnetic pole axis when the rotor 30 is at rest, there is no need to demagnetize the residual magnetic flux, and the direction of the holding torque generated in the stator 20 is When the direction of the magnetic pole axis of the rotor and the direction of the magnetic pole axis of the rotor at the rest position of the rotor 30 are different from each other, it is necessary to demagnetize the residual magnetic flux.
In this case, the degaussing pulse Pe may be applied when the direction of the holding torque generated in the stator 20 due to the application of the drive pulse and the direction of the magnetic pole axis of the rotor at the rest position of the rotor 30 are different from each other. .
Therefore, the control unit 112 can prevent the degaussing pulse Pe from being output at an unnecessary timing, so the control unit 112 can prevent malfunctions. Furthermore, the control unit 112 can suppress power consumption.

In the embodiment described above, a specific example in which the demagnetizing pulse Pe is generated by one-phase excitation has been described, but the demagnetizing pulse Pe may be outputted by two-phase excitation. In this case, the degaussing pulse Pe is a two-phase excitation pulse that generates a torque that maintains the rotation angle of the rotor 30 in a direction that matches the rest angle of the rotor 30.
The control unit 112 can more reliably demagnetize the residual magnetic flux when the demagnetizing pulse Pe is a double-layer excitation pulse.

In addition, in the embodiment mentioned above, the case where there are two coils was described, but the embodiment of the present invention can be similarly applied to the case where there are three or more coils.

Although the embodiments of the present invention have been described above with reference to the drawings, the specific configuration is not limited to the above-described embodiments, and design changes may be made without departing from the gist of the present invention.

DESCRIPTION OF SYMBOLS 1... Analog electronic clock, 101... Oscillation circuit, 102... Frequency dividing circuit, 103... Control circuit, 104... Motor drive circuit, 105... Stepping motor, 121... Drive pulse generation circuit, 122... Demagnetizing pulse generation circuit, 106... Analog Display unit, 107...Hour hand, 108...Minute hand, 109...Second hand, 110...Calendar display unit, 112...Control unit, 113...Watch case, 114...Watch movement, 25...Rotor accommodation hole, 20...Stator, 20A...No. 1 magnetic pole part, 20B...second magnetic pole part, 20C...third magnetic pole part, 21...stator main body, 22a...straight part, 22b...projection part, 22c...projection part, 22...first yoke, 23...th 2 yoke, 24...second yoke, 25a...notch, 26...notch, 30...rotor, 40A...first magnetic core, 40B...second magnetic core, 50A...first coil, 50Aa...first terminal, 50Ab...th 2 terminals, 50B...second coil, 50Ba...first terminal, 50Bb...second terminal, PG...pulse group

Claims (12)

a rotor that is magnetized with at least two poles, a north pole and a south pole, and rotates the pointer;
a stator that provides a magnetic flux that generates a rotational force to the rotor;
a first coil that supplies magnetic flux to a first end of both ends of the stator;
a second coil that supplies magnetic flux to a second end different from the first end among both ends of the stator;
A stepping motor control device for driving a stepping motor comprising:
a drive pulse generation circuit that outputs a drive pulse that rotates the rotor by exciting the first coil and the second coil;
a degaussing pulse generation circuit that outputs a degaussing pulse that reduces residual magnetic flux generated when the driving pulse is applied;
Equipped with
The degaussing pulse is a two-phase excitation pulse that generates a torque that maintains the rotation angle of the rotor in a direction that coincides with the rest angle of the rotor.
Stepping motor control device. The drive pulse is a pulse that rotates the rotor by a reference rotation angle corresponding to the number of poles,
After the drive pulse generation circuit finishes applying the drive pulse, the degaussing pulse generation circuit detects at least a position where the magnetic pole axis of the rotor and the magnetic pole axis of the excited stator coincide with each other due to the rotation of the rotor. The stepping motor control device according to claim 1, wherein a degaussing pulse is output after one pass. The stepping motor according to claim 2, wherein the polarity of the degaussing pulse is opposite to the polarity of any of the drive pulses among the plurality of drive pulses applied when the rotor rotates by the reference rotation angle. Control device. The polarity of the degaussing pulse is opposite to the polarity of the drive pulse that is applied last among the plurality of drive pulses that are applied when the rotor rotates by the reference rotation angle. 3. The stepping motor control device according to any one of 3. The polarity of the degaussing pulse is opposite to the polarity of the drive pulse having the largest energy among the plurality of drive pulses applied when the rotor rotates by the reference rotation angle. The stepping motor control device according to any one of the above. The degaussing pulse is applied at least 5 ms after the first of the plurality of drive pulses applied when the rotor rotates by the reference rotation angle . The stepping motor control device according to any one of Item 5. The degaussing pulse is applied after the last driving pulse is applied after the plurality of driving pulses applied when the rotor rotates by the reference rotation angle are continuously applied multiple times. A stepping motor control device according to any one of claims 2 to 6. The degaussing pulse is applied between the continuously applied driving pulses when the polarities of the successively applied driving pulses are different from each other. The stepping motor control device described in . The degaussing pulse is applied when the direction of the holding torque generated in the stator due to the application of the drive pulse and the direction of the magnetic pole axis of the rotor at the rest position of the rotor are different from each other. 9. The stepping motor control device according to claim 8 . A stepping motor control device according to any one of claims 1 to 9 ,
A movement comprising: the stepping motor; A timepiece comprising the movement according to claim 10 . a rotor that is magnetized with at least two poles, a north pole and a south pole, and rotates the pointer;
a stator that provides magnetic flux that generates rotational force to the rotor;
a first coil that supplies magnetic flux to a first end of both ends of the stator;
a second coil that supplies magnetic flux to a second end different from the first end among both ends of the stator;
A stepping motor control method for driving a stepping motor comprising:
outputting a drive pulse that rotates the rotor by exciting the first coil and the second coil;
outputting a degaussing pulse that reduces residual magnetic flux generated when the driving pulse is applied;
The degaussing pulse is a two-phase excitation pulse that generates a torque that maintains the rotation angle of the rotor in a direction that coincides with the rest angle of the rotor.
Stepping motor control method.

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