JP2019158355A - Motor drive circuit, semiconductor device, movement, and electronic timepiece - Google Patents

Abstract

To provide a motor drive circuit, a movement and an electronic timepiece with which it is possible to speed up the fast forward drive of a step motor equipped with two coil blocks.SOLUTION: Provided is a motor drive circuit for driving a step motor 13 equipped with a stator 61 having a first yoke 611, a second yoke 612 and a third yoke 613, a rotor 62, and a first coil block 63 and a second coil block 64. The first coil block magnetically connects the first and the second yokes, and the second coil block magnetically connects the first and the third yokes. The motor drive circuit outputs a prescribed number of drive pulses corresponding to the direction and amount of rotation of the rotor to one of the first and the second coils, and after outputting the last drive pulse of the prescribed number of drive pulses to the one coil, outputs a correction pulse for causing a magnetic field whose direction is the same as that of the last drive pulse in the first yoke to the other coil.SELECTED DRAWING: Figure 4

Description

  The present invention relates to a motor drive circuit, a semiconductor device, a movement, and an electronic timepiece.

  As a reversible stepping motor capable of normal rotation and reverse rotation, a rotor magnetized with two or more poles, a stator having three stator magnetic pole portions, two coils, and a driving means for outputting a driving pulse to each coil A reversible step motor is known (see, for example, Patent Document 1).

  When the reversible step motor is driven at a high speed, the rotor may rotate one step many times due to variations, disturbances, and the like. In order to make it less susceptible to such variations and disturbances, it is necessary to increase the pulse width of the driving pulse during high-speed driving.

JP 2006-101618 A

  However, when the pulse width of the drive pulse is increased, there is a problem that it is difficult to increase the speed of the fast-forward drive because the drive pulse frequency is restricted from being increased.

  An object of the present invention is to provide a motor drive circuit, a semiconductor device, a movement, and an electronic timepiece that can speed up fast-forward drive of a step motor including two coil blocks.

  A motor drive circuit of the present invention is a motor drive circuit that drives a step motor that includes a stator having a first yoke, a second yoke, and a third yoke, a rotor, and a first coil block and a second coil block. The first coil block includes a first coil, the first yoke and the second yoke are magnetically connected, and the second coil block includes a second coil, the first yoke and the A third yoke is magnetically connected, and the motor drive circuit outputs a predetermined number of drive pulses corresponding to the rotation direction and rotation amount of the rotor to the first coil or the second coil, and After the last drive pulse in the drive pulse is output to one of the first coil and the second coil, the last drive pulse is generated. And outputs the correction pulse to generate a magnetic field having the same direction in the magnetic field direction as the first yoke of that in the other coil.

In the present invention, the motor drive circuit is configured to output a predetermined number of drive pulses corresponding to the rotation direction and the rotation amount of the rotor to the first coil or the second coil. For example, when the two-pole rotor is rotated 30 times in the first direction, the motor drive circuit alternately outputs 60 drive pulses to the two terminals of the first coil. Each time a drive pulse is output to the two terminals, the magnetic pole of the first yoke changes alternately to the N pole and the S pole. Further, since the second yoke is magnetically connected to the first yoke by the first coil block, the second yoke is alternately changed to a magnetic pole different from that of the first yoke by the magnetic field generated by the first coil. On the other hand, since the third yoke is magnetically connected to the first yoke through a second coil block having a second coil to which no drive pulse is input, the same magnetic pole as the second yoke, that is, the same as the first yoke. It changes alternately to the magnetic pole. Therefore, each time a drive pulse is output, the rotor rotates 180 degrees, and after the last drive pulse (60th drive pulse) is output, the rotor rotates normally after the first drive pulse. The rotor stops in a state where one magnetic pole of the rotor is attracted to the magnetic pole generated in the above.
On the other hand, when the rotor rotates one step more, the rotor further rotates 180 degrees with respect to the normal operation, so the rotor after the output of the last drive pulse (60th drive pulse) is applied to the first yoke. The opposing rotor magnetic poles are stopped in a state where the magnetic poles are the same as the magnetic poles generated in the first yoke by the last drive pulse.
Then, the motor drive circuit outputs the last drive pulse to one of the first coil and the second coil, and then outputs the correction pulse to the other coil. In the correction pulse, the direction of the magnetic field generated in the first yoke by the correction pulse (the magnetic pole of the first yoke) is the same as the direction of the magnetic field generated in the first yoke by the last drive pulse (the magnetic pole of the first yoke). Is a pulse. Therefore, when a drive pulse is output to the first coil, the correction pulse is output to the second coil, the third yoke has a different magnetic pole from the first yoke, and the second yoke has the same magnetic pole as the first yoke. Become.
Therefore, when the rotor operates normally, the rotor is stopped in a state where one magnetic pole is attracted to the magnetic pole generated in the first yoke by the last drive pulse, and therefore the same magnetic pole is applied to the first yoke by the correction pulse. Even if this occurs, the motor does not rotate and remains stopped.
On the other hand, when the rotor rotates one step more, the rotor is stopped in a state where one of the magnetic poles is repelled from the magnetic pole generated in the first yoke by the last drive pulse. And a magnetic pole different from the last drive pulse is generated in the second and third yokes, so that the rotor rotates backward by one step and returns to the same state as when normal operation ends.
As described above, according to the motor drive circuit of the present invention, the stop position of the rotor can be corrected only when the rotor rotates by one step more. For this reason, it is not necessary to increase the width of the drive pulse in order to make it less susceptible to variations and disturbances, and the fast-forward drive of the step motor can be speeded up.

Preferably, the motor driving circuit outputs the correction pulse after the rotor has stopped after the output of the last driving pulse.
In the present invention, the motor drive circuit outputs the correction pulse after the rotor stops after outputting the last drive pulse. Therefore, by outputting the correction pulse after the rotor position is stabilized, it is possible to prevent the rotor from rotating to an incorrect position.

Preferably, the motor drive circuit includes a stop detection unit that detects a stop of the rotor, and outputs the correction pulse based on a detection result of the stop detection unit.
In the present invention, since the motor drive circuit has stop detection means for detecting the stop of the rotor, it is possible to reliably detect that the rotation of the rotor has stopped. Therefore, the correction pulse can be output after the rotor position is reliably stabilized, and the rotor can be reliably prevented from rotating to an incorrect position.

The stop detection means includes a detection pulse output circuit that outputs a detection pulse to the first coil or the second coil after the output of the last drive pulse, and the rotor based on a detection signal generated by the detection pulse. A detection circuit that detects that the motor has stopped, and the motor driving circuit outputs the correction pulse when detecting that the voltage of the detection signal detected by the detection circuit is equal to or lower than a threshold value. preferable.
In the present invention, the stop detection means includes a detection pulse output circuit that outputs a detection pulse to the first coil or the second coil, and a detection circuit that detects that the voltage of the detection signal generated by the detection pulse is equal to or less than a threshold value. Have. That is, the stop detection means has a detection pulse output circuit that outputs a detection pulse to either the first coil or the second coil, or to both the first coil and the second coil. The stop detection means for detecting the stop of the rotor can be realized using a rotation detection sensor or the like, but the stop detection means of the present invention can be realized with a simple configuration. That is, since the detection pulse output circuit can use a motor drive circuit, the stop detection means can be configured simply by adding a detection circuit, the circuit configuration can be simplified, and the cost can be reduced.

The motor driving circuit preferably outputs the correction pulse after the first time has elapsed and before the second time has elapsed after outputting the last driving pulse.
In the present invention, the motor drive circuit outputs the correction pulse after the first time has elapsed after outputting the last drive pulse. By setting the first time as the time until the rotor stops after the last drive pulse is output, the correction pulse can be output after the rotor position is stabilized, and the rotor rotates to the wrong position. Can be prevented. Further, by outputting the correction pulse within the second time, the time from when the rotor stops to when the correction pulse is output can be set within a predetermined time. Thereby, the operation until the fast-forwarding operation of the rotor is completed and the rotor is reversely rotated and corrected can be made a series of operations, and the movement of the pointer linked to the rotation of the rotor can be made inconspicuous.

A semiconductor device according to the present invention includes the motor drive circuit.
According to this semiconductor device, the stop position of the rotor can be corrected only when the rotor rotates one step more. For this reason, it is not necessary to increase the width of the drive pulse in order to make it less susceptible to variations and disturbances, and the fast-forward drive of the step motor can be speeded up.

The movement of the present invention includes the motor drive circuit, the step motor, and a train wheel driven by the step motor.
According to this movement, the stop position of the rotor can be corrected only when the rotor rotates one step more, so there is no need to increase the width of the drive pulse in order to make it less susceptible to variations and disturbances. The fast-forward drive can be speeded up. Furthermore, since it is not necessary to increase the width of the drive pulse at the time of fast-forwarding of the step motor, power consumption at the time of fast-forward driving can be reduced.

An electronic timepiece according to the invention includes the movement and a pointer driven by the movement.
According to this electronic timepiece, the pointer driven by the movement can be fast-forwarded and can be corrected to the correct position by the correction pulse even if the pointer is shifted by one step at the end of fast-forwarding. Therefore, it is possible to reduce the power consumption, and to reduce the influence of fluctuations and disturbances during fast-forwarding of the pointer, and to provide an easy-to-use electronic timepiece.

The figure which shows the electronic timepiece which concerns on one Embodiment of this invention. The figure which shows the circuit structure of a movement. The block diagram which shows the outline of the motor drive circuit of the said electronic timepiece. The figure which shows the outline of the step motor of the said electronic timepiece. The figure which shows the signal waveform of the drive pulse when a rotor rotates counterclockwise. The schematic diagram which shows a mode that a rotor rotates counterclockwise. The schematic diagram which shows a mode that a rotor rotates counterclockwise. The schematic diagram which shows a mode that a rotor rotates counterclockwise. The schematic diagram which shows a mode that a rotor rotates counterclockwise. The figure which shows the signal waveform of the drive pulse at the time of a rotor rotating clockwise. The schematic diagram which shows a mode that a rotor rotates clockwise. The schematic diagram which shows a mode that a rotor rotates clockwise. The schematic diagram which shows a mode that a rotor rotates clockwise. The schematic diagram which shows a mode that a rotor rotates clockwise. The flowchart explaining the hand movement process of the said electronic timepiece. The figure which shows the signal waveform of a drive pulse and a correction pulse. The schematic diagram which shows a mode that a rotor does not rotate with a correction pulse. The schematic diagram which shows a mode that a rotor rotates with a correction pulse.

Hereinafter, an electronic timepiece 1 according to an embodiment of the present invention will be described with reference to the drawings.
The electronic timepiece 1 is a radio wave correction clock that can receive standard radio waves, acquire time information, and correct the display time. As shown in FIG. 1, the electronic timepiece 1 is a wristwatch worn on a user's wrist, and includes an outer case 2, a disk-shaped dial 3, a movement 10 (see FIG. 2), and a movement 10. The second hand 5, the minute hand 6, and the hour hand 7 which are hands driven by the motor 13 (see FIG. 2) provided on the hand, and the crown 8 and the button 9 which are operation members.

[Circuit configuration of the movement]
FIG. 2 is a diagram illustrating a circuit configuration of the movement 10.
As shown in FIG. 2, the movement 10 includes a crystal resonator 11 as a signal source, a battery 12 as a power source, a switch S1 that is turned on / off in conjunction with the operation of the button 9, and a drawer of the crown 8. Is provided with a slide switch S2 that is turned on and off in conjunction with the motor, a motor 13, a train wheel 14 that moves the hands 5 to 7, a receiving IC 17, and an IC 20 for a watch.
IC 20 includes connection terminals OSC1 and OSC2 to which crystal resonator 11 is connected, input / output terminals P1 and P2 to which switches S1 and S2 are connected, input / output terminals P3 to P6 to which reception IC 17 is connected, and battery 12. Are connected to power supply terminals VDD and VSS, and output terminals O1 to O4 connected to input terminals of the motor 13.
In this embodiment, the positive electrode of the battery 12 is connected to the power terminal VDD on the high potential side, the negative electrode is connected to the power terminal VSS on the low potential side, and the power terminal VDD on the high potential side is grounded (reference). Potential).

The crystal unit 11 is driven by an oscillation circuit 21 described later to generate an oscillation signal having a predetermined frequency (32768 Hz).
The battery 12 is composed of a primary battery or a secondary battery. In the case of a secondary battery, it is charged by a solar cell (not shown).
The motor 13 is a step motor and is driven by a driving pulse output from the IC 20. Details of the motor 13 will be described later.
The second hand 5, the minute hand 6, and the hour hand 7 are interlocked by a train wheel 14 and are driven by a motor 13 to display the second, minute, and hour. In the present embodiment, the second hand 5, the minute hand 6, and the hour hand 7 are driven by a single motor 13. For example, a motor that drives the second hand 5, and a motor that drives the minute hand 6 and the hour hand 7 are used. A plurality of motors may be provided.
The switch S1 is input in conjunction with the button 9 at the 2 o'clock position of the electronic timepiece 1. For example, the switch S1 is turned on when the button 9 is pressed, and is turned off when the button 9 is not pressed. .
The switch S2 is a slide switch interlocked with the drawer 8 being pulled out. In the present embodiment, the crown 8 is turned on when it is pulled out to the first stage, and is turned off at the zeroth stage.
In the present embodiment, when the crown 8 is pulled out to the first stage (switch S2 is on), functions such as manual time adjustment are executed, and the motor S13 is turned on by pressing the button 9 to turn on the switch S1. Is driven to correct the hand positions of the second hand 5, the minute hand 6 and the hour hand 7.

  The receiving IC 17 and the antenna 18 are common in radio-controlled timepieces that receive predetermined standard radio waves, such as JJY and WWVB, and acquire time information, and thus description thereof is omitted.

[IC circuit configuration]
As shown in FIG. 3, the IC 20 includes an oscillation circuit 21, a frequency dividing circuit 22, a CPU (Central Processing Unit) 23 for controlling the electronic timepiece 1, a ROM (Read Only Memory) 24, A random access memory (RAM) 25, an input / output circuit 26, a bus (BUS) 27, a motor drive circuit 30, and a detection circuit 40 are provided. The IC 20 is an example of a semiconductor device of the present invention.

The oscillation circuit 21 oscillates the crystal unit 11 serving as a reference signal source at a high frequency, and outputs a 32768 Hz oscillation signal generated by the high frequency oscillation to the frequency dividing circuit 22.
The frequency dividing circuit 22 divides the output of the oscillation circuit 21 and supplies a timing signal (clock signal) to the CPU 23.
The ROM 24 stores various programs executed by the CPU 23.
The RAM 25 stores information necessary when the CPU 23 executes the program.
The CPU 23 executes a program stored in the ROM 24 and realizes the above functions.

The input / output circuit 26 outputs the states of the input / output terminals P1 to P6 to the bus 27.
The bus 27 is used for data transfer between the CPU 23, the RAM 25, the input / output circuit 26, the motor drive circuit 30, and the detection circuit 40.

The motor drive circuit 30 outputs a predetermined drive pulse to the motor 13 in accordance with a command input from the CPU 23 through the bus 27.
The detection circuit 40 detects the rotation state of the motor 13 and detects that the rotation of the motor 13 has ended (rotation has stopped).

[Step motor]
As shown in FIG. 4, the motor 13 is a step motor having a stator 61, a rotor 62, a first coil block 63, and a second coil block 64, and is an example of the step motor of the present invention.
The rotor 62 is magnetized in two poles (S pole and N pole) and is rotatably arranged in a rotor accommodation hole 614 of a stator body 610 described later. The rotor 62 is rotatable in both the counterclockwise direction and the clockwise direction by drive pulses input to input terminals M1 to M4 described later.

  The stator 61 is made of a magnetic material and includes a first yoke 611, a second yoke 612, and a third yoke 613. A rotor accommodating hole 614 that is a circular hole is formed at the intersection of the first yoke 611, the second yoke 612, and the third yoke 613. The second yoke 612 and the third yoke 613 are arranged substantially linearly with the rotor housing hole 614 interposed therebetween, and the first yoke 611 is in a direction substantially orthogonal to the second yoke 612 and the third yoke 613. Has been placed. In addition, the portion where the first yoke 611, the second yoke 612, and the third yoke 613 are coupled around the rotor accommodation hole 614 has a smaller width than the yokes 611 to 613, and magnetic saturation is likely to occur. The resistance is a large saturated portion. In addition, notches are formed in the rotor accommodation hole 614 in accordance with the positions of the yokes 611 to 613.

The first coil block 63 includes a first core 631 formed of a magnetic material and a first coil 632 wound around the first core 631, and the first yoke 611 and the second yoke 612 are magnetically connected. Connect to. The first coil 632 is provided with input terminals M1 and M2 connected to the output terminals O1 and O2 of the motor drive circuit 30, respectively. In the present embodiment, when a drive pulse is input to the input terminal M1, a clockwise magnetic field is generated in the first coil block 63, and when a drive pulse is input to the input terminal M2, the first coil block 63 is The first coil 632 is wound so that a counterclockwise magnetic field is generated.
The second coil block 64 has a second core 641 formed of a magnetic material and a second coil 642 wound around the second core 641, and the first yoke 611 and the third yoke 613 are magnetically connected. Connect to. The second coil 642 is provided with input terminals M3 and M4 connected to the output terminals O3 and O4 of the motor drive circuit 30, respectively. In the present embodiment, when a driving pulse is input to the input terminal M3, a clockwise magnetic field is generated in the second coil block 64, and when a driving pulse is input to the input terminal M4, The second coil 642 is wound so that a counterclockwise magnetic field is generated.
In the present embodiment, the first core 631 and the second core 641 are integrally formed. In addition, the 1st core 631 and the 2nd core 641 are not restricted to what is formed integrally, For example, you may isolate | separate into two independent cores, respectively.
Further, in the present embodiment, the second yoke 612 and the third yoke 613 are arranged substantially linearly with the rotor accommodating hole 614 interposed therebetween, and the first yoke 611 is relative to the second yoke 612 and the third yoke 613. Although it is assumed that they are arranged in a substantially orthogonal direction, the present invention is not limited to this. As long as the first coil block 63 can magnetically connect the first yoke 611 and the second yoke 612 and the second coil block 64 can magnetically connect the first yoke 611 and the third yoke 613, it is sufficient. . Further, the first yoke 611 may be formed integrally with the second yoke 612 and the third yoke 613, or may be formed separately.

[Driving pulse when the rotor rotates counterclockwise]
Next, in the motor 13, the operation | movement at the time of rotating the rotor 62 to a 1st direction (counterclockwise) is demonstrated based on FIGS. In order to make the explanation easy to understand, the timing of each operation will be described in six stages A1 to F1.
FIG. 5 is a diagram showing signal waveforms of drive pulses output from the motor drive circuit 30 when the rotor 62 rotates counterclockwise. FIGS. 6 to 9 are diagrams when the rotor 62 rotates counterclockwise. It is a schematic diagram which shows a mode.
As shown in FIG. 5, the motor drive circuit 30 outputs a drive pulse to the input terminal M2 of the first coil 632 at the timing A1. Here, in the present embodiment, as shown in FIG. 2, since the power terminal VDD on the high potential side is set to the ground (reference potential), the input terminals M1 to M4 are normally at the H level. Therefore, as shown in FIG. 5, the voltage of the input terminal M1 is lowered to L level, and a potential difference is generated between the input terminal M1 and the input terminal M2, thereby inputting a drive pulse to the input terminal M2. I have to.
When a drive pulse (main drive pulse) is input to the input terminal M2 at timing A1, the magnetic path constituted by the first coil block 63, the second yoke 612, and the first yoke 611, as shown in FIG. In FIG. 6, the magnetic flux flows counterclockwise, the magnetic pole at the end of the second yoke 612 on the rotor receiving hole 614 side is an N pole, and the magnetic pole at the end of the first yoke 611 is an S pole. In addition, a magnetic flux flows in the counterclockwise direction in FIG. 6 in the magnetic path constituted by the first coil block 63, the second yoke 612, the third yoke 613, and the second coil block 64, and the end of the third yoke 613 The magnetic pole is the S pole. At this time, the magnetic flux density passing through the third yoke 613 and the second coil block 64 is lower than the magnetic flux density passing through the first coil block 63, the second yoke 612 and the first yoke 611.
As described above, when a counterclockwise magnetic flux flows through the first coil block 63 and the second coil block 64, the N pole of the rotor 62 in the state shown in FIG. 6 repels the N pole of the second yoke 612, The three yokes 613 are attracted to the south pole. Further, the south pole of the rotor 62 repels the south pole of the first yoke 611 and the third yoke 613 and is attracted to the north pole of the second yoke 612. Thereby, the rotor 62 rotates counterclockwise.

  Next, the motor drive circuit 30 outputs an auxiliary pulse having a short pulse width to the input terminal M3 of the second coil 642 while outputting a drive pulse to the input terminal M2 at timing B1 in FIG. This auxiliary pulse is an auxiliary pulse for suppressing fluctuation of the rotor 62 and stably stopping the rotor 62 at a position rotated by 180 degrees. When an auxiliary pulse is input to the input terminal M3, an N pole is generated in the third yoke 613 as shown in FIG. For this reason, since the first yoke 611 is the S pole and the second yoke 612 and the third yoke 613 are both the N pole, the rotor 62 is positioned at the position where the N pole faces the first yoke 611, that is, the position shown in FIG. Move to a position rotated 180 degrees and stop. In other words, the rotor 62 rotates 180 degrees counterclockwise from the state shown in FIG. 6 by the drive pulse for one step input to the input terminal M2, and rotates 180 degrees by the auxiliary pulse input to the input terminal M3. It stops at the position where it was, and can suppress fluctuation.

Next, the motor drive circuit 30 sets all of the input terminals M1 to M4 to the H level and sets the first coil 632 and the second coil 642 to the non-excited state at the timing C1 in FIG.
Next, the motor drive circuit 30 outputs a drive pulse to the input terminal M1 of the first coil 632 at the timing D1 in FIG. Then, as shown in FIG. 8, a clockwise magnetic flux in FIG. 6 flows in the magnetic path constituted by the first coil block 63, the first yoke 611, and the second yoke 612, and the N pole is applied to the first yoke 611. The S pole is generated in the second yoke 612. Further, a clockwise magnetic flux also flows in the magnetic path constituted by the first coil block 63, the second coil block 64, the third yoke 613, and the second yoke 612, and an N pole is generated in the third yoke 613. Therefore, from the state of FIG. 8, the south pole of the rotor 62 repels the south pole generated in the second yoke 612 and is attracted to the north pole of the third yoke 613, and the north pole of the rotor 62 is drawn to the third yoke 613. Repels the N pole of the first yoke 611 and is attracted to the S pole of the second yoke 612. Thereby, the rotor 62 rotates counterclockwise.

Next, the motor drive circuit 30 outputs an auxiliary pulse to the input terminal M4 of the second coil 642 while outputting a drive pulse to the input terminal M1 at a timing E1 in FIG. Then, the third yoke 613 switches from the N pole to the S pole. For this reason, since the first yoke 611 is the N pole, and the second yoke 612 and the third yoke 613 are both the S pole, the rotor 62 is positioned at the position where the S pole faces the first yoke 611, that is, the position shown in FIG. Move to a position rotated 180 degrees and stop. That is, the rotor 62 rotates 180 degrees counterclockwise from the state shown in FIG. 8 by the driving pulse for one step input to the input terminal M1, and rotates 180 degrees by the auxiliary pulse input to the input terminal M4. Stop at the specified position.
Next, the motor drive circuit 30 sets all of the input terminals M1 to M4 to the H level and sets the first coil 632 and the second coil 642 to the non-excited state at the timing F1 in FIG.
As described above, in this embodiment, the rotor 62 rotates once in the counterclockwise direction by alternately inputting the drive pulse to the input terminals M1 and M2 of the first coil 632. Further, by inputting auxiliary pulses to the input terminals M3 and M4 of the second coil 642, the rotor 62 can be stably stopped at a position of every 180 degrees.
The motor drive circuit 30 can rotate the rotor 62 a predetermined number of times in the counterclockwise direction by repeating the operations at the timings A1 to F1 shown in FIG.

[Driving pulse when the rotor rotates clockwise]
Next, the operation when the rotor 62 rotates clockwise will be described with reference to FIGS. 10 to 14 in which the timing is divided into six stages A2 to F2.
FIG. 10 is a diagram illustrating signal waveforms of drive pulses output from the motor drive circuit 30 when the rotor 62 rotates clockwise. FIGS. 11 to 14 illustrate the case where the rotor 62 rotates clockwise. It is a schematic diagram which shows a mode.
As shown in FIGS. 10 to 12, the driving pulse is input to the input terminals M <b> 3 and M <b> 4 of the second coil 642, contrary to the above-described counterclockwise rotation. Specifically, at timings A2 and B2, a driving pulse is input to the input terminal M3 of the second coil 642, and the rotor 62 rotates 180 degrees clockwise. At this time, the auxiliary pulse is input to the input terminal M2 of the first coil 632 at the timing B2.
Next, after entering the non-excited state at timing C2, as shown in FIGS. 13 and 14, at timings D2 and E2, a drive pulse is input to the input terminal M4 of the second coil block 64, and the rotor 62 moves to the right It rotates 180 degrees in the turning direction. At this time, the auxiliary pulse is input to the input terminal M1 of the first coil 632 at the timing E2. Then, at timing F2, a non-excited state is entered.
Thus, in the present embodiment, the rotor 62 rotates once in the clockwise direction by the drive pulses for two steps input to the second coil block 64. That is, the motor drive circuit 30 can rotate the rotor 62 a predetermined number of times in the clockwise direction by repeating the operations at the timings A2 to F2 shown in FIG.

[Operation of electronic watch]
Next, the operation at the time of fast-forwarding in this embodiment will be described with reference to the flowchart of FIG. In the present embodiment, when correcting the time based on a predetermined standard radio wave received by the receiving IC 17, the rotor 62 is rotated at a high speed so that the position of each pointer 5-7 is corrected by fast-forwarding. To do.
15 is not limited to the operation for correcting the positions of the pointers 5 to 7 based on the standard radio wave. For example, a pointer for time measurement (for chronograph) is used. It can be used for an operation when returning from a stop position at the end of measurement to a reference position (for example, 12 o'clock position). Further, the rotation direction of the rotor 62 may be either left or right. Normally, the rotor 62 may be rotated in the rotation direction that shortens the moving distance when the positions of the pointers 5 to 7 are corrected. If the rotor 62 is rotated in this way, the correction time of the hands 5-7 can be shortened and power can be saved.

As shown in FIGS. 15 and 16, the CPU 23 operates the motor drive circuit 30 to correct the positions of the hands 5 to 7 and drives a predetermined number of times according to the rotation direction and the rotation amount of the rotor 62. A pulse is output. Specifically, the motor drive circuit 30 alternately outputs n steps of fast-forward pulses as a predetermined number of drive pulses to the input terminal M1 and the input terminal M2 of the first coil 632 (S1). Then, the rotor 62 is rotated n / 2 counterclockwise by the driving pulse for n steps, and the positions of the hands 5 to 7 are corrected. Therefore, in FIG. 16, the nth drive pulse is the last drive pulse.
When the rotor 62 is rotated clockwise, n steps of driving pulses are alternately output to the input terminal M3 and the input terminal M4 of the second coil 642.

After a predetermined number of fast-forward pulses are output, the CPU 23 outputs a detection pulse by the motor drive circuit 30 (S2). That is, in the present embodiment, the motor drive circuit 30 is configured to function also as the detection pulse output circuit of the present invention. The motor drive circuit 30 is not limited to be configured to function as a detection pulse output circuit, and the motor drive circuit and the detection pulse output circuit may be provided separately.
Here, in this embodiment, the motor drive circuit 30 outputs a detection pulse to the first coil 632 or the second coil 642. That is, the motor drive circuit 30 may output the detection pulse to either the first coil 632 or the second coil 642, or may output the detection pulse to both the first coil 632 and the second coil 642. Good. At this time, the motor drive circuit 30 may output detection pulses independently and simultaneously to the first coil 632 and the second coil 642, or may output detection pulses independently and at different timings.

Next, the detection circuit 40 detects the voltage of the detection signal generated by the detection pulse. Then, the CPU 23 determines that the rotation of the rotor 62 has stopped when the voltage detected by the detection circuit 40 becomes equal to or less than a predetermined threshold value stored in the ROM 24 or RAM 25 (S3). That is, in this embodiment, the motor drive circuit 30 and the detection circuit 40 are an example of a stop detection unit of the present invention.
CPU23 repeats the process of S2 and S3, when it determines with NO by S3. On the other hand, if the CPU 23 determines YES in S3, the motor drive circuit 30 outputs a correction pulse (S4). Thus, in the present embodiment, the motor drive circuit 30 is based on the detection results of the motor drive circuit 30 and the detection circuit 40 that are stop detection means after the nth drive pulse that is the last drive pulse is output. Output a correction pulse.

  Here, when the first coil 632 to which the last drive pulse is input is used as one coil, the correction pulse is output to the second coil 642 that is the other coil. Specifically, as shown in FIG. 16, it is output to the input terminal M3 of the second coil 642. As shown in FIG. 17, the N pole is generated in the first yoke 611 by the correction pulse. That is, the correction pulse generates a magnetic field having the same direction in the first yoke 611 as the nth driving pulse as the last driving pulse.

  At this time, as shown in FIG. 17, the n-th drive pulse, that is, the last drive pulse, generates the N pole in the first yoke 611. Therefore, the rotor 62 normally has the S pole in the first yoke 611. It stops in a state of being attracted to the generated N pole. Therefore, even if the correction pulse is output to the second coil 642, the rotor 62 does not rotate.

On the other hand, when the motor 13 is driven at a high speed, the rotor 62 may rotate one step more due to variations, disturbances, and the like. That is, as shown in FIG. 18, after the nth drive pulse is output, the rotor 62 may stop with the N pole facing the first yoke 611 side.
In this case, when a correction pulse is output to the second coil 642, the S pole of the rotor 62 is attracted to the N pole of the second yoke 612 as shown in FIG. Further, the N pole of the rotor 62 repels the N pole of the first yoke 611 and is attracted to the S pole of the third yoke 613, so that it rotates 180 degrees clockwise, which is the direction opposite to the direction rotated by the last drive pulse. Then, the state after the correction pulse in FIG. 18, that is, the position where the south pole of the rotor 62 faces the first yoke 611 is stopped. That is, the stop position of the rotor 62 is corrected by the correction pulse.
Thus, in this embodiment, after the last drive pulse is output to one coil, the correction pulse is output to the other coil, so that when the rotor 62 is rotating correctly, the stopped state is maintained. Only when the rotor 62 is rotated by one step more can the stop position of the rotor 62 be corrected, and the pointers 5 to 7 can be corrected to correct positions.
When the rotor 62 is rotated clockwise, that is, when the last drive pulse is output to the second coil 642, the correction pulse is output to the first coil 632.

[Effects of Embodiment]
According to this embodiment, the following effects can be obtained.
In the present embodiment, the motor drive circuit 30 outputs a predetermined number of drive pulses corresponding to the rotation direction and the rotation amount of the rotor 62 to the first coil 632 or the second coil 642, and the first coil 632 or the second coil 642. After the last drive pulse is output to one of the coils, a correction pulse is output to the other coil. In the correction pulse, the direction of the magnetic field generated in the first yoke 611 by the correction pulse (the magnetic pole of the first yoke 611) is the same as the direction of the magnetic field generated in the first yoke 611 by the last drive pulse (the magnetic pole of the first yoke 611). The pulse has the same direction as.
Therefore, when the rotor 62 operates normally, the rotor 62 stops in a state where one of the magnetic poles is attracted to the magnetic pole generated in the first yoke 611 by the last drive pulse. Even if the same magnetic pole is generated in 611, the stopped state can be maintained without rotating.
On the other hand, when the rotor 62 rotates one step more, the rotor 62 is stopped in a state where one magnetic pole repels the magnetic pole generated in the first yoke 611 by the last drive pulse. For this reason, the same magnetic pole is generated in the first yoke 611 by the correction pulse, and the magnetic pole different from the last driving pulse is generated in the second and third yokes 612 and 613, so that the rotor 62 is reversely rotated by one step. And return to the same state as at the end of normal operation.
As described above, according to the motor drive circuit 30 of the present embodiment, the stop position of the rotor 62 can be corrected only when the rotor 62 rotates by one step. Therefore, it is not necessary to increase the width of the drive pulse in order to make it less susceptible to variations and disturbances, and the fast-forward drive of the motor 13 can be speeded up.

  In the present embodiment, the motor drive circuit 30 outputs a correction pulse after the rotor 62 stops after outputting the last drive pulse. Therefore, the rotation of the rotor 62 in the wrong direction can be suppressed by outputting the correction pulse after the position of the rotor 62 is stabilized.

  In the present embodiment, the stop detection means for detecting the rotation stop of the rotor 62 is configured by the motor drive circuit 30 and the detection circuit 40, and thus can be realized with a simple configuration as compared with the case where a rotation detection sensor or the like is used. That is, since the motor drive circuit 30 is used as the detection pulse output circuit, the stop detection means can be configured only by adding the detection circuit 40, the circuit configuration can be simplified, and the cost can be reduced.

[Other Embodiments]
It should be noted that the present invention is not limited to the above-described embodiments, and modifications, improvements, and the like within the scope that can achieve the object of the present invention are included in the present invention.
In the above embodiment, the motor drive circuit 30 outputs the correction pulse after the induced voltage detected by the detection circuit 40 becomes equal to or lower than the threshold value. For example, the motor drive circuit outputs the last drive pulse. After that, the correction pulse may be output after the first time and before the second time. The first time can be an average time until the rotor stops after the last drive pulse is output, and for example, a time of about 30 msec is exemplified. Thereby, a correction pulse can be output after the position of the rotor is stabilized, and the rotor can be prevented from rotating to an incorrect position. Further, as the second time, for example, a time of about 100 msec is exemplified. By outputting the correction pulse within the second time, the time from when the rotor stops to when the correction pulse is output can also be set within a predetermined time. If the time from when the rotor stops to when it rotates backward with the correction pulse is long, the possibility that the user will notice the reverse rotation of the pointer increases. On the other hand, if the correction pulse is output within about 100 msec from the time of the last drive pulse output, the rotor stop time is short, so that the reverse rotation of the pointer can be made inconspicuous, and the possibility of the user noticing can be reduced. Thereby, the operation until the fast-forwarding operation of the rotor is completed and the rotor is reversely rotated and corrected can be made a series of operations, and the movement of the pointer linked to the rotation of the rotor can be made inconspicuous.
In the above-described embodiment, the motor drive circuit 30 outputs the correction pulse after the rotor 62 stops. However, the motor drive circuit outputs the correction pulse before the rotor 62 stops after outputting the last drive pulse. May be output. This is because even if the rotor 62 is not stopped, a correction pulse can be input at a position almost close to the stop position if the timing is just before the stop, and the rotor 62 can be corrected to the correct position.

  In the embodiment, the motor drive circuit 30 outputs the auxiliary pulse to the coil block opposite to the coil block that outputs the drive pulse after outputting the drive pulse. In the case where it can be secured to some extent, the auxiliary pulse does not necessarily have to be output. However, the output of the auxiliary pulse has the advantage that the pulse width of the drive pulse can be shortened, and the frequency of the drive pulse can be increased correspondingly, thereby enabling higher speed driving.

  DESCRIPTION OF SYMBOLS 1 ... Electronic timepiece, 5 ... Second hand (pointer), 6 ... Minute hand (pointer), 7 ... Hour hand (pointer), 10 ... Movement, 13 ... Motor (step motor), 14 ... Wheel train, 20 ... IC (semiconductor device) 30 ... Motor drive circuit, 40 ... detection circuit, 61 ... stator, 611 ... first yoke, 612 ... second yoke, 613 ... third yoke, 62 ... rotor, 63 ... first coil block, 631 ... first core 632 ... 1st coil, 64 ... 2nd coil block, 641 ... 2nd core, 642 ... 2nd coil.

Claims (8)

A motor drive circuit for driving a step motor comprising a stator having a first yoke, a second yoke and a third yoke, a rotor, and a first coil block and a second coil block,
The first coil block includes a first coil, and magnetically connects the first yoke and the second yoke;
The second coil block includes a second coil, and magnetically connects the first yoke and the third yoke;
Outputting a predetermined number of drive pulses to the first coil or the second coil according to the rotation direction and the rotation amount of the rotor;
After outputting the last drive pulse in the predetermined number of drive pulses to one of the first coil and the second coil, the direction of the magnetic field generated by the last drive pulse is the same as that in the first yoke. A motor drive circuit that outputs a correction pulse that generates a magnetic field to the other coil. The motor drive circuit according to claim 1,
The motor drive circuit outputs the correction pulse after the rotor stops after the output of the last drive pulse. The motor drive circuit according to claim 2,
Having stop detection means for detecting stop of the rotor,
The motor drive circuit outputs the correction pulse based on a detection result of the stop detection means. In the motor drive circuit according to claim 3,
The stop detection means includes
A detection pulse output circuit for outputting a detection pulse to the first coil or the second coil after the output of the last drive pulse;
A detection circuit that detects that the rotor has stopped based on a detection signal generated by the detection pulse;
The motor drive circuit outputs the correction pulse when detecting that the voltage of the detection signal detected by the detection circuit is not more than a threshold value. The motor drive circuit according to claim 1,
The motor driving circuit outputs the correction pulse after the first time has elapsed and before the second time has elapsed after outputting the last driving pulse. A semiconductor device comprising the motor drive circuit according to any one of claims 1 to 5. The motor drive circuit according to any one of claims 1 to 5,
The step motor;
A wheel train driven by the step motor. A movement according to claim 7;
An electronic timepiece comprising: a pointer driven by the movement.

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