JP6916688B2 - Drive device - Google Patents

Description

The present invention relates to a timepiece drive device using a step motor in an analog display type electronic timepiece.

Conventionally, in an electronic clock provided with analog display means, the pointer is generally driven by a step motor. This step motor is composed of a stator magnetized by a coil and a rotor which is a disk-shaped rotating body magnetized by two poles. For example, the rotor is rotated 180 degrees every second to display the time by a pointer. is doing.

In such an analog display type electronic clock using a step motor, the display position may shift due to the backlash of the train wheel that moves the pointer or the like. In order to solve such a problem, the drive pulse for driving the step motor has a two-step configuration consisting of a first drive pulse and a second drive pulse, and the output interval between the first drive pulse and the second drive pulse is set. An electronic clock having a motor control circuit having a value of 50 ms or less has been proposed (see, for example, Patent Document 1).

According to the electronic clock of Patent Document 1, the rotation speed of the rotor can be set to, for example, twice the normal rotation speed. As a result, the reduction ratio from the rotor to the second display vehicle can be increased, and the deviation of the pointer display position due to backlash is improved.

Further, as a drive method of a step motor used in an analog display type electronic clock, it has been proposed that the first and second coils are connected to a common connection point and the current applied is switched every three phases. (See, for example, Patent Document 2).

Japanese Patent No. 3166654 Japanese Unexamined Patent Publication No. 2016-178742

Electronic clocks not only drive the pointer on a regular basis to display the current time, but also drive the pointer continuously and faster to set the time and present information other than the time (in the following, "fast forward". ") May be described. The inventors are considering, for example, changing the unit of rotation at one time from 180 degrees to 360 degrees and rotating the step motor at high speed. In order to rotate the step motor at a higher speed, it is conceivable to shorten the strength and interval of each pulse applied to the coil of the step motor, but due to environmental factors such as temperature and voltage fluctuation, the desired rotation angle It may turn too much. On the other hand, in order to prevent it from turning too much, it is necessary to take measures such as weakening the pulse in anticipation of a margin, and the fast-forward operation becomes slow.

An object of the present invention has been made in view of the above problems, and an object of the present invention is to provide an electronic clock capable of driving a step motor at high speed.

In order to solve the above problems, the electronic clock of the present invention adopts the configuration described below.

(1) A step motor having a rotor magnetized with two or more poles, a first unit drive signal for rotating the rotor toward a predetermined stable position, and rotating the rotor toward the predetermined stable position. , A second unit drive signal in which the rotation speed of the rotor at the stable position is smaller than the first unit drive signal, and a control circuit capable of selectively outputting any one of them as a unit drive signal to the step motor. When the control circuit sequentially outputs a plurality of the unit drive signals and stops the rotor at the predetermined stable position, the plurality of the unit drive signals are the first unit drive signal and the said. A clock drive device including a second unit drive signal, wherein the control circuit outputs the second unit drive signal as at least the last unit drive signal.

(2) In (1), the step motor further includes a plurality of stators that transmit a magnetic force to the rotor, and a plurality of coils that generate a magnetic field toward the plurality of stators. A clock drive device that outputs a first unit drive signal and the second unit drive signal to the plurality of coils.

(3) In (2), the first unit drive signal generates a magnetic field from the stator that attracts one pole of the rotor to the first position at the end timing, and the second unit drive signal ends. A clock driving device that generates a magnetic field from the stator that attracts the one pole of the rotor to a second position in front of the first position at the timing.

(4) In (2), the second unit drive signal is a signal in which the magnetic field applied by the stator to the rotor is stronger than that of the first unit drive signal, or the time during which the magnetic field is applied is the first. A clock drive that contains at least the last signal longer than the unit drive signal.

(5) In (3), the second unit drive signal is a clock drive device that weakens the magnetic field applied by the stator to the rotor at the end timing as compared with the first unit drive signal.

(6) In any one of (1) to (5), the detection circuit for detecting the rotation of the rotor is further provided, and the control circuit is based on the detected rotation of the rotor. A clock drive device that controls the time to output a unit drive signal.

(7) In any one of (1) to (5), at least one of the first unit drive signal and the second unit drive signal is a variable signal whose period changes and a variable signal following the variable signal. A clock drive that includes a fixed signal that is output and does not change in duration.

(8) In (6), at least one of the first unit drive signal and the second unit drive signal is a variable signal whose period changes according to the detected rotation of the rotor and the variable signal. A clock drive that includes a fixed signal that is output followed by a fixed period that does not change in duration.

(9) In any one of (1) to (8), at least one of the first unit drive signal and the second unit drive signal is at least one of a plurality of wirings connected to the step motor. A clock drive device including a chopper signal that repeatedly applies a first potential and a second potential different from the first potential.

(10) In (9), the chopper signal repeats a first potential and a second potential different from the first potential in at least one of the plurality of wirings connected to the step motor. A clock drive device that applies a current signal and applies a second current signal different from the first signal to the other one of the plurality of wirings.

(11) In any of (1) to (10), the unit drive signal includes a first partial signal for rotating the rotor to the first rotation angle and a second rotation angle larger than the first rotation angle. A clock driving device including a second partial signal to be rotated and a third partial signal to be rotated to the predetermined rotation angle larger than the second rotation angle.

(12) In any of (1) to (10), the first unit drive signal is a first partial signal that rotates the rotor to the first rotation angle and a second partial signal that is larger than the first rotation angle. A second partial signal that rotates to the rotation angle, a third partial signal that rotates to a third rotation angle that is larger than the second rotation angle, and a fourth portion that rotates to a fourth rotation angle that is larger than the third rotation angle. A clock drive device that includes a signal and the second unit drive signal does not include the fourth partial signal.

(13) In any one of (1) to (12), the clock drive device in which the rotor makes one rotation by the unit drive signal.

According to the present invention, the step motor can be driven at a higher speed.

It is a top view which shows an example of the electronic clock which concerns on 1st Embodiment. It is a figure which shows schematic the circuit structure of the electronic timepiece which concerns on 1st Embodiment. It is a figure which shows the structure of a step motor. It is a circuit diagram which shows an example of the structure of a driver circuit and a rotation detection determination circuit. It is a figure explaining the detection method of the rotation of a step motor. It is a figure which shows an example of the waveform of the 1st unit drive signal and the 2nd unit drive signal. It is a flow chart which shows an example of the processing of a motor control part. It is a figure which schematically explains the relationship between the 1st unit drive signal and the operation of a transistor. It is a figure which shows an example of the operation of the step motor by the 1st unit drive signal. It is a figure which schematically explains the relationship between the 2nd unit drive signal and the operation of a transistor. It is a figure which shows an example of the operation of the step motor by the 2nd unit drive signal. It is a waveform diagram explaining another example of the waveform by the drive pulse SP30. It is a flow chart which shows an example of the processing of the detection of rotation and the output of the head drive pulse and the first trailer drive pulse. It is a figure which shows the waveform of the induced current generated in coil A and coil B, and the detection signal output from coil terminals O1 to O4 by a detection pulse. It is a waveform diagram explaining another example of the waveform by the drive pulse SP40. It is a figure which shows the state of excitation in the state B. It is a waveform diagram explaining another example of the waveform by the drive pulse SP41. It is a figure which shows another example of the 2nd unit drive signal. It is a figure which shows another example of the 2nd unit drive signal. It is a figure which shows another example of the waveform of a unit drive signal. It is a figure which shows another example of the operation of the step motor by the 2nd unit drive signal. It is a figure which shows another example of the waveform of a unit drive signal. It is a figure which shows another example of the operation of the step motor by the 2nd unit drive signal. FIG. 5 is a waveform diagram schematically showing an example of a first unit drive signal and an operation diagram of a step motor in the second embodiment. It is a waveform diagram which shows typically an example of the 2nd unit drive signal in 2nd Embodiment. It is a waveform diagram which shows the other example of the 2nd unit drive signal schematicly. It is a waveform diagram which shows the other example of the 2nd unit drive signal schematicly.

Hereinafter, embodiments of the present invention will be described in detail together with the drawings. Hereinafter, a case where the present invention is applied to a portable electronic timepiece will be described.

[First Embodiment]
FIG. 1 is a plan view showing an example of the electronic clock 1 of the first embodiment, and FIG. 2 is a diagram schematically showing a circuit configuration of the electronic clock 1. The electronic clock 1 is an analog display type electronic clock. The electronic clock 1 includes a dial 51, an hour hand 52a, a minute hand 52b, a second hand 52c, a motor control unit 2, a step motor 20, a train wheel (not shown), and a power supply (not shown). The step motor 20 is a so-called two-coil step motor. The step motor 20 is mechanically connected to the train wheel. The motor control unit 2 includes a pulse switching control unit 3, a step number setting unit 4, a step count unit 5, a waveform generation unit 6, a selector 9, a driver circuit 10, and a rotation detection circuit 11. The motor control unit 2 is implemented as an integrated circuit including, for example, a microcontroller. The power source includes, for example, a secondary battery. The waveform generation unit 6 includes a head drive pulse generation circuit 61, a first successor drive pulse generation circuit 62, a second successor drive pulse generation circuit 63, and a detection pulse generation circuit 66. A clock signal from an oscillation circuit (not shown) is input to the waveform generation unit 6.

The head drive pulse generation circuit 61 generates and outputs a head drive pulse SP30 for driving the step motor 20. The first subsequent drive pulse generation circuit 62 generates and outputs a first subsequent drive pulse SP40 for driving the step motor 20. The second subsequent drive pulse generation circuit 63 generates and outputs a second subsequent drive pulse SP41 for driving the step motor 20. The detection pulse generation circuit 66 generates and outputs a detection pulse CP for detecting rotation. Each of the first drive pulse SP30, the first subsequent drive pulse SP40, and the second subsequent drive pulse SP41 (hereinafter collectively referred to as "drive pulse") controls four buffer circuits included in the driver circuit 10 described later. Then, the drive waveforms O1 to O4 (drive signals) are output. Each of the drive pulse and the detection pulse CP is composed of, for example, 4 bits. Details of the first drive pulse SP30, the first subsequent drive pulse SP40, the second subsequent drive pulse SP41, and the detection pulse CP will be described later.

The step count unit 5 increases or decreases the value of the counter sc indicating the current position of the pointer according to the drive of the step motor 20. The step number setting unit 4 sets the initial value sc0 of the counter sc used by the step count unit 5.

At the time of fast-forwarding, the pulse switching control unit 3 outputs a switching signal for switching the drive pulse output from the selector 9 according to the value of the counter sc indicating the current position of the pointer.

The head drive pulse SP30, the first subsequent drive pulse SP40, the second subsequent drive pulse SP41, and the detection pulse CP are input to the selector 9. Then, the selector 9 outputs any one of the first drive pulse SP30, the first subsequent drive pulse SP40, the second subsequent drive pulse SP41, and the detection pulse CP based on the switching signal input from the pulse switching control unit 3. do.

One of the head drive pulse SP30, the first subsequent drive pulse SP40, the second subsequent drive pulse SP41, and the detection pulse CP is input to the driver circuit 10 from the selector 9. The driver circuit 10 supplies drive waveforms O1 to O4 (drive signals) corresponding to the input drive pulses to the coils A and B of the step motor 20 to drive the step motor 20 or respond to the detection pulse CP. The counter electromotive force generated in the coil A and the coil B is input to the rotation detection circuit 11. The detailed configuration of the driver circuit 10 will be described later.

The step motor 20 has two coils, a coil A and a coil B. The step motor 20 is arranged to drive, for example, the second hand 52c of the electronic clock 1. Details of the step motor 20 are described below.

FIG. 3 is a plan view showing the configuration of the step motor 20. The step motor 20 is composed of a rotor 21, a stator 22, two coils A, a coil B, and the like. The rotor 21 is a disk-shaped rotating body magnetized with two poles, and has north and south poles magnetized in the radial direction.

The stator 22 is made of a soft magnetic material, is provided with a rotor hole 22d into which the rotor 21 is inserted, and the rotor 21 is arranged in the rotor hole 22d. The stator 22 has a first magnetic pole portion 22a and a second magnetic pole portion 22b that face each other with the rotor 21 in between. Further, the stator 22 has a third magnetic pole portion 22c between the first magnetic pole portion 22a and the second magnetic pole portion 22b at a position facing the rotor 21.

Further, a coil A as a first coil that is magnetically coupled to the first magnetic pole portion 22a and the third magnetic pole portion 22c, and a second coil that is magnetically coupled to the second magnetic pole portion 22b and the third magnetic pole portion 22c. Coil B is provided. When at least one of the coils A and B is excited, a magnetic force is transmitted to the stator 22. Further, the first magnetic pole portion 22a, the second magnetic pole portion 22b, and the third magnetic pole portion 22c apply a magnetic field to the rotor 21.

The coil A has coil terminals O1 and O2 on the insulating substrate 23a, and both ends of the winding of the coil A are connected to each other. Further, the coil B has coil terminals O3 and O4 on the insulating substrate 23b, and both ends of the winding of the coil B are connected to each other. Each coil terminal O1 to O4 is connected to the driver circuit 10 by wiring. The drive waveforms O1 to O4 output from the driver circuit 10 described above are supplied to the coil terminals O1 to O4 via wiring.

For ease of explanation, the codes of each coil terminal and each supplied drive waveform are shared. Further, in an example of the present embodiment, the coil terminal O1 is connected to the winding start of the coil A, and the coil terminal O4 is connected to the winding start of the coil B.

Further, the rotor 21 is in the stationary state, for example, at the position shown in FIG. In the following, the upper part of the drawing is defined as 0 degrees, and 90 degrees, 180 degrees, and 270 degrees counterclockwise from that position. The rotor 21 is a stable position (static stability point) at which the north pole is finally stationary when it is located at 0 degrees and when it is located at 180 degrees. In the rotor 21 shown in FIG. 3, the north pole is at a stable position of 0 degrees.

A narrowed portion 25 in which the width of the stator 22 is narrowed is provided between the first magnetic pole portion 22a and the second magnetic pole portion 22b, which is opposite to the third magnetic pole portion 22c with the rotor 21 in between. Further, the slit 24 is provided at a position approximately 75 degrees to the left and right with the direction of the third magnetic pole portion 22c when viewed from the center of the rotor 21. The slit 24 does not directly magnetically connect the first magnetic pole portion 22a and the third magnetic pole portion 22c, and the second magnetic pole portion 22b and the third magnetic pole portion 22c. The slit 24 may be a gap as shown here, or a narrow non-magnetic material may be inserted at the position of the slit 24 and coupled with the stator 22. Further, instead of the slit 24, a region where the width of the stator 22 is narrowed may be provided at the position of the slit 24.

The narrowed portion 25 and the slit 24 increase the detection sensitivity when the induced current induced by the rotation of the rotor 21 is detected by using the coils A and B. While a drive signal is given to the step motor 20 and it is rotating and while it is freely rotating due to the inertia of the rotor 21, the magnetism generated in the stator 22 by electromagnetic induction causes the narrowed portion 25 and the slit 24 having a large magnetic resistance. This is because it becomes difficult to pass through, and most of the magnetism takes a path through the coil A or the coil B. The relationship between rotation detection and detection pulse CP will be described later.

FIG. 4 is a circuit diagram showing an example of the configuration of the driver circuit 10. The driver circuit 10 is composed of four buffer circuits that supply drive waveforms O1 to O4 to the coils A and B of the step motor 20.

Explaining the configuration of these four buffer circuits, first, a buffer circuit composed of a complementary connection of a transistor P1 which is a P-channel MOS transistor having a low ON resistance and a transistor N1 which is an N-channel MOS transistor having a low ON resistance is described. The drive waveform O1 is output, and the output drive waveform O1 is supplied to the coil terminal O1 of the coil A.

Similarly, the buffer circuit composed of the complementary connection of the transistor P2 and the transistor N2 having low ON resistance outputs the drive waveform O2, and the output drive waveform O2 is supplied to the coil terminal O2 of the coil A.

Similarly, a buffer circuit composed of a complementary connection of a transistor P3 and a transistor N3 having a low ON resistance outputs a drive waveform O3, and the output drive waveform O3 is supplied to the coil terminal O3 of the coil B.

Similarly, a buffer circuit composed of a complementary connection between the low ON resistance transistor P4 and the transistor N4 outputs a drive waveform O4, and the output drive waveform O4 is supplied to the coil terminal O4 of the coil B.

Although not shown, drive pulses output from the selector 9 are input to the gate terminals G of the transistors P1 to P4 and N1 to N4. Each transistor is ON / OFF controlled based on the input drive pulse, and drive waveforms O1 to O4 are output. Here, when the drive pulse is composed of 4 bits as described above, the 4 bits are input to the gate terminals G of the transistors of the four buffer circuits, respectively. Then, the drive waveforms O1 to O4 corresponding to each of the drive pulses are supplied to the step motor 20. When the step motor 20 is rotated, the head drive pulse SP30 is input to the driver circuit 10, and then the first subsequent drive pulse SP40 or the second subsequent drive pulse SP41 is input.

Transistors TP1 and TP2, which are P-channel MOS transistors, are connected to the coil terminals O1 and O2 of the coil A via detection resistors, respectively, and the detection resistors to the coil terminals O3 and O4 of the coil B, respectively. Transistors TP3 and TP4, which are P-channel MOS transistors, are connected to each other via the above. A detection pulse CP is output to the transistors TP1 to TP4, and the detection signal CS obtained thereby is input to the rotation detection circuit 11.

That is, by turning on the transistors TP1 to TP4 shown in FIG. 4 at a predetermined timing by the detection pulse CP, the magnitude of the induced current generated in the coil terminals O1 to O4 corresponding to each transistor is a voltage signal. It can be taken out as a detection signal CS. The rotation detection circuit 11 determines whether the rotor 21 is rotating or not rotating based on the detection signal CS, and outputs the determination result CK to, for example, the pulse switching control unit 3.

FIG. 5 is a diagram illustrating a method for detecting rotation and non-rotation of the rotor 21 of the step motor 20. FIG. 5A shows a case where the rotor 21 does not rotate, that is, the rotor 21 does not rotate at a desired angle even though a drive signal is applied to the step motor 20, and the rotation fails. In this case, a drive signal is input and the rotor 21 rotates counterclockwise once, but due to insufficient driving force, the rotor 21 rotates counterclockwise due to the holding torque and returns to the initial position of 0 degrees. Will be done. In this case, the rotor 21 does not rotate at all in the end, so this is referred to as non-rotation. In the figure, the rotation of the rotor 21 during the period when a certain drive signal is output is shown by a broken line.

FIG. 5B shows a case where the rotor 21 rotates, that is, the rotor 21 rotates at a desired angle by the applied drive signal and succeeds in rotation. In this case, the drive signal is input and the rotor 21 rotates counterclockwise by a certain angle or more, so that even after the input of the drive signal is stopped, the rotor 21 further rotates counterclockwise due to the holding torque, and the rotation target position in one step. Rotate up to 180 degrees. In this case, the rotor 21 is finally rotated to the target rotation position for one step, and this is referred to as rotation.

As described above, the behavior of the rotor 21 after the drive signal output is different between the case where the rotor 21 is rotating and the case where the rotor 21 is not rotating, and therefore the waveforms of the induced currents generated in the coils A and B are also different. This difference in waveform is taken out as a detection signal CS by the detection pulse CP, and the rotation detection circuit 11 determines the rotation / non-rotation of the rotor 21. The details of detecting the waveform of the induced current will be described later.

[Summary of 1st and 2nd unit drive signals input to the step motor]
Next, a drive system for fast-forwarding using the step motor 20 will be described. In the following description, an example will be described in which the rotor 21 makes one rotation when one first unit drive signal D1 or a second unit drive signal D2 is input to the step motor 20. In this example, in the case of fast forward, the unit of rotation is 360 degrees. Although the details will not be described in this embodiment, for example, the unit of rotation may be 180 degrees in the driving state in which the second hand 52c points to the time.

FIG. 6 is a diagram showing an example of waveforms of the first unit drive signal D1 and the second unit drive signal D2. Hereinafter, the first unit drive signal D1 and the second unit drive signal D2 are collectively referred to as a unit drive signal. At the time of fast forward, as shown in FIG. 6, the motor control unit 2 selects either the first unit drive signal D1 or the second unit drive signal D2 when sequentially outputting a plurality of unit drive signals. Is output to the step motor 20. When the motor control unit 2 sequentially outputs a plurality of unit drive signals, the plurality of unit drive signals include a first unit drive signal D1 and a second unit drive signal D2. Further, the motor control unit 2 outputs a second unit drive signal D2 as at least the last unit drive signal. In the example of FIG. 6, the motor control unit 2 outputs the first unit drive signal D1 as the unit drive signal from the beginning to the last one.

Here, the unit drive signal is a signal for rotating the rotor 21 by a unit of rotation (360 degrees in this case), and is a signal for rotating the north pole of the rotor 21 once to a stable position. According to the first unit drive signal D1, the rotation speed is high after the first unit drive signal D1 is supplied and when the rotor 21 reaches the stable position, and according to the second unit drive signal D2, the second unit drive signal. The rotation speed is slow after D2 is supplied and when the rotor 21 reaches a stable position. The unit drive signal may be a signal that rotates the rotor 21 from a certain stable position to any stable position, and may be, for example, a signal that rotates the rotor 21 by 180 degrees or 540 degrees.

Each of the first unit drive signals D1 is output when the first drive pulse SP30 and the subsequent first subsequent drive pulse SP40 are input to the driver circuit 10. Further, each of the second unit drive signals D2 is output when the first drive pulse SP30 and the subsequent second subsequent drive pulse SP41 are input to the driver circuit 10. Each of the detection pulse CPs is output at predetermined time intervals within the period during which the head drive pulse SP30 is output, and in the example of FIG. 6, the potential of the coil terminal O3 changes according to the detection pulse CP. In the example of FIG. 6, in each of the periods in which the head drive pulse SP30, the first subsequent drive pulse SP40, and the second unit drive signal D2 are output, the coil terminals O1 to O3 are provided except for the period in which the detection pulse CP is output. Although the applied potentials are substantially constant, in reality, so-called chopper control is performed in which the transistors are turned on and off a plurality of times in each period, and a plurality of potentials may be output at a predetermined duty ratio.

FIG. 7 is a flow chart showing an example of the processing of the motor control unit 2, and is a diagram for explaining the processing for switching the output between the first unit drive signal D1 and the second unit drive signal D2. The processing of the motor control unit 2 may be provided by a microcontroller having a processor and a memory executing a program stored in the memory, or may be provided by a programmable logic circuit. Also, a microcontroller or programmable logic circuit may be provided as an integrated circuit.

First, the motor control unit 2 acquires the current position of the pointer and the target position of the pointer (step S101). For example, when the processing target of the motor control unit 2 is the second hand 52c, information indicating which second position the second hand 52c points to on the dial 51 and information indicating which second position is to be targeted are provided. To get. The value indicating the target position is a value indicating the position of the pointer according to the current time when fast-forwarding to indicate the current time, and when the pointer presents information different from the time, the guideline indicated by the information. It is a value indicating the position of.

Next, the step number setting unit 4 included in the motor control unit 2 sets the initial value sc0 of the counter sc (step S102). When the down counter is used, the initial value sc0 of the counter sc is the number of steps required to move from the current position to the target position. Further, the target step value so indicating the target position at this time is 0. The initial value sc0 of the counter sc may be another value. For example, when an up counter is used, the initial value sc0 of the counter sc may be 0 or a step value indicating the current position. In this case, the step number setting unit 4 sets the target step value so as the fast-forward end condition. The target step value so is a value indicating a target position, and may be obtained by the same method as, for example, the initial value sc0 of the counter sc in the down counter.

When the initial value sc0 of the counter sc is set, the iterative process for fast-forwarding the pointer is executed. In the iterative process, first, it is determined whether the difference between the value of the counter sc and the target step value so corresponds to one rotation unit (360 degrees) (2 or less) (step S103).

When the difference does not correspond to one rotation unit, that is, when the next unit drive signal is not the final unit drive signal (N in step S103), the pulse switching control unit 3 outputs the SP30 selection signal as the switching signal. (Step S104), and after the SP30 selection signal is output for a required period, the SP40 selection signal is output (step S105). As a result, the driver circuit 10 of the motor control unit 2 outputs the first unit drive signal D1.

On the other hand, when the difference corresponds to one rotation unit, that is, when the next unit drive signal becomes the final unit drive signal (Y in step S103), the pulse switching control unit 3 uses the SP30 selection signal as the switching signal. It is output (step S106), and after the SP30 selection signal is output for a required period, the SP41 selection signal is output (step S107). As a result, the driver circuit 10 of the motor control unit 2 outputs the second unit drive signal D2.

When the SP40 selection signal or the SP41 selection signal is output, the step count unit 5 reduces the counter sc by 2 (step S108). Here, the amount of change in the counter sc corresponds to the number of steps in which the driving body such as the pointer moves by the unit driving pulse.

Then, the motor control unit 2 compares the value of the counter sc with the target step value so (step S109). If the value of the counter sc and the target step value so are not equal (N in step S109), the processes after step S103 are repeated. On the other hand, when the value of the counter sc and the target step value so are equal (Y in step S109), the process of controlling the fast forward ends. By the process shown in FIG. 7, the first unit drive signal D1 is output from the driver circuit 10 as the unit drive signal from the beginning to the last one, and the second unit drive signal D2 is output as the final unit drive signal. NS.

[Outline of rotation of step motor by 1st unit drive signal]
Next, an outline of the operation in which the step motor 20 is rotated by the first unit drive signal D1 will be described. FIG. 8 is a diagram schematically explaining the relationship between the first unit drive signal D1 and the operation of the transistor. FIG. 9 is a diagram showing an example of the operation of the step motor 20 by the first unit drive signal D1.

FIG. 8A is a simplified version of the waveform shown in FIG. FIG. 8A shows the north pole of the rotor 21 of the step motor 20 360 degrees in the forward rotation direction (counterclockwise) from the stable position 0 degrees (see FIG. 3) by the first drive pulse SP30 and the first subsequent drive pulse SP40. An example of the drive waveforms O1 to O4 in the case of rotationally driving in units is shown.

In FIG. 8A, the first drive pulse SP11 is output as the head drive pulse SP30, and then the second drive pulse SP12 and the third drive pulse SP13 included in the first subsequent drive pulse SP40 are sequentially output. Here, the first drive pulse SP11, the second drive pulse SP12, and the third drive pulse SP13 are pulses only for rotating the rotor 21 to a certain position, and the potentials or duty ratios of the drive waveforms O1 to O4 are constant. be. Hereinafter, the first drive pulse SP11, the second drive pulse SP12, and the third drive pulse SP13 are collectively referred to as partial pulses. Here, the signals output by the driver circuit 10 by the first drive pulse SP11, the second drive pulse SP12, and the third drive pulse SP13 are referred to as a first partial signal, a second partial signal, and a third partial signal, respectively.

When the first drive pulse SP11 is supplied, the drive waveform O3 has a voltage −V, and the other drive waveforms O1, O2, and O4 have a voltage of 0 V. As a result, a drive current flows through the coil B of the step motor 20 connected to the drive waveforms O3 and O4 to be excited.

When the second drive pulse SP12 is supplied, the drive waveforms O2 and O4 have a voltage −V, and the drive waveforms O1 and O3 have a voltage of 0V. As a result, a drive current flows through both the coil A and the coil B of the step motor 20, and both the coil A and the coil B are excited.

When the third drive pulse SP13 is supplied, the drive waveforms O1 and O4 have a voltage −V, and the other drive waveforms O2 and O3 have a voltage of 0V. As a result, the coil B of the step motor 20 is excited in the same direction as the second drive pulse SP12, and the coil A is excited in the direction opposite to the second drive pulse SP12.

Further, the pulse widths of the first to third drive pulses SP11 to SP13 are arbitrary. Further, although each of the partial pulses included in the drive waveforms O1 to O4 is shown as a continuous full pulse, in reality, the first potential and the second potential different from the first potential are repeatedly applied. It may be a chopper signal by a plurality of fine pulse groups.

Next, the operation of each transistor of the driver circuit 10 by the first drive pulse SP30 and the first subsequent drive pulse SP40 will be described with reference to the operation table of FIG. 8B. In FIG. 8B, when the first drive pulse SP11 is supplied, the drive waveform O3 becomes a voltage −V and the drive waveform O4 becomes a voltage 0V, so that the transistor N3 and the transistor P4 are turned on, and the transistor P3 and the transistor N4 are turned on. When it is turned off, the drive current flows from the coil terminal O4 of the coil B to the coil terminal O3, and the coil B is excited.

Further, since the drive waveforms O1 and O2 both have a voltage of 0 V, the transistors P1 and P2 are turned on, the transistors N1 and N2 are turned off, the drive current does not flow through the coil A, and the coil A is not excited.

Further, when the second drive pulse SP12 is supplied, the drive waveform O1 has a voltage of 0 V and the drive waveform O2 has a voltage of −V, so that the transistor P1 and the transistor N2 are turned on, the transistor N1 and the transistor P2 are turned off, and the drive current Flows from the coil terminal O1 to the coil terminal O2, and the coil A is excited. Further, since the drive waveform O3 has a voltage of 0 V and the drive waveform O4 has a voltage −V, the transistor P3 and the transistor N4 are turned on, the transistor N3 and the transistor P4 are turned off, and the drive current flows from the coil terminal O3 to the coil terminal O4. The coil B is excited.

When the third drive pulse SP13 is supplied, the drive waveform O3 has a voltage of 0 V and the drive waveform O4 has a voltage of −V. Therefore, the transistor P3 and the transistor N4 are turned on, the transistor N3 and the transistor P4 are turned off, and the drive current Flows from the coil terminal O3 to the coil terminal O4, and the coil B is excited. Further, since the drive waveform O1 has a voltage of 0 V and the drive waveform O2 has a voltage −V, the transistors N1 and P2 are turned on, the transistors P1 and N2 are turned off, the drive current flows from the coil terminal O2 to the coil terminal O1, and the coil A. Is excited.

In this way, each transistor of the driver circuit 10 is ON / OFF controlled by the three first to third drive pulses SP11 to SP13 during the period in which the first unit drive signal D1 is output, and the coil A of the step motor 20 is controlled. , B is excited.

Next, a high-speed rotary drive of the step motor 20 in units of 360 degrees in one step by the first unit drive signal D1 will be described with reference to FIG. FIG. 9A shows the initial state of the step motor 20, and the north pole of the rotor 21 is at the stable position of 0 degrees. Further, the reference numerals of the respective members of the step motor 20 are shown only in FIG. 9A, and the others are omitted.

FIG. 9B shows a state in which the first drive pulse SP11 is supplied to the driver circuit 10 and the corresponding signal is supplied to the step motor 20. In this case, as described above, the drive current (not shown). ) Flows from the coil terminal O4 to the coil terminal O3, and the coil B is excited in the direction of the arrow. As a result, the second magnetic pole portion 22b is magnetized to the N pole, the third magnetic pole portion 22c is magnetized to the S pole, and the coil A is not excited, so that the first magnetic pole portion 22a has the same S pole as the third magnetic pole portion 22c. ..

As a result, the north pole of the rotor 21 and the south pole of the first magnetic pole portion 22a and the third magnetic pole portion 22c are attracted to each other, and the south pole of the rotor 21 and the north pole of the second magnetic pole portion 22b are attracted to each other, and the rotor 21 is counterclockwise. Rotating clockwise, the north pole of the rotor 21 rotates from a stable position of 0 degrees to a position of about 135 degrees.

Next, in FIG. 9C, when the second drive pulse SP12 is supplied, a drive current (not shown) flows from the coil terminal O1 to the coil terminal O2, and the coil A moves in the direction of the arrow, as described above. Is excited by. Similarly, a drive current (not shown) flows from the coil terminal O3 to the coil terminal O4, and the coil B is excited in the direction of the arrow (direction opposite to the coil A).

As a result, the first magnetic pole portion 22a is magnetized to the N pole, the second magnetic pole portion 22b is magnetized to the S pole, and the magnetizations of the third magnetic pole portion 22c cancel each other out and are not magnetized. As a result, the north pole of the rotor 21 and the south pole of the second magnetic pole portion 22b are attracted to each other, and the south pole of the rotor 21 and the north pole of the first magnetic pole portion 22a are attracted to each other, so that the rotor 21 is further counterclockwise without stopping. The north pole of the rotor 21 rotates to a position of about 270 degrees.

Next, in FIG. 9D, when the third drive pulse SP13 is supplied, a drive current (not shown) flows from the coil terminal O3 to the coil terminal O4, and the coil B moves in the direction of the arrow, as described above. Is excited by. Further, a drive current (not shown) flows from the coil terminal O2 to the coil terminal O1, and the coil A is excited in the direction of the arrow (the same direction as the coil B). As a result, the first magnetic pole portion 22a and the second magnetic pole portion 22b are magnetized to the S pole, and the third magnetic pole portion 22c is magnetized to the N pole. As a result, the south pole of the rotor 21 and the north pole of the third magnetic pole portion 22c are attracted to each other, the rotor 21 rotates further counterclockwise without stopping, and the north pole of the rotor 21 is 360 degrees (same as the stable position). Rotate to.

Here, in driving the step motor 20 by the first unit drive signal D1, the magnetic field generated from the stator 22 by the third drive pulse SP13 draws the north pole of the rotor 21 to the position of 360 degrees (first position). be. Then, after the north pole of the rotor 21 reaches 0 degrees, the position of the north pole of the rotor 21 is rotated to the previous position due to inertia. How far it rotates and whether it returns to the original 360-degree position depends on the timing at which the magnetic force is applied, the magnitude of the magnetic force, the amount of rotation of the rotor 21, etc., but in the example of FIG. 9, the excitation ends. After that, the position of the north pole of the rotor 21 may exceed 90 degrees, and the position of the north pole of the rotor 21 may rotate to the position of 180 degrees, which is another stable position.

[Outline of rotation of step motor by 2nd unit drive signal]
Next, the rotation of the step motor 20 will be described by the second unit drive signal D2, which is unlikely to rotate too much. FIG. 10 is a diagram schematically explaining the relationship between the second unit drive signal D2 and the operation of the transistor. FIG. 11 is a diagram showing an example of the operation of the step motor 20 by the second unit drive signal D2.

FIG. 10A is a diagram corresponding to FIG. 8A. FIG. 10A shows the north pole of the rotor 21 of the step motor 20 360 degrees in the forward rotation direction (counterclockwise) from the stable position 0 degrees (see FIG. 3) by the first drive pulse SP30 and the second subsequent drive pulse SP41. An example of the drive waveforms O1 to O4 in the case of rotationally driving in units is shown.

In FIG. 10A, the first drive pulse SP11 is output as the head drive pulse SP30, and then the second drive pulse SP12 and the third drive pulse SP13 included in the second subsequent drive pulse SP41 are sequentially output. The first drive pulse SP30 (first drive pulse SP11) is the same as the example of FIG. 8A, and the second drive pulse SP12 included in the second subsequent drive pulse SP41 is included in the first subsequent drive pulse SP40. The same is true. The third drive pulse SP13, which has a difference, will be described below.

When the third drive pulse SP13 is supplied, the drive waveform O4 has a voltage −V, and the other drive waveforms O1, O2, and O3 have a voltage of 0 V. As a result, the coil B of the step motor 20 is excited in the same direction as the second drive pulse SP12.

Further, the pulse widths of the first to third drive pulses SP11 to SP13 are arbitrary. Further, although each of the partial pulses included in the drive waveforms O1 to O4 is shown as a continuous full pulse, in reality, the first potential and the second potential different from the first potential are repeatedly applied. It may be a chopper signal by a plurality of fine pulse groups.

FIG. 10 (b) is a diagram corresponding to FIG. 8 (b). The third drive pulse SP13, which is different from FIG. 8B, will be mainly described below.

When the third drive pulse SP13 is supplied, the drive waveform O3 has a voltage of 0 V and the drive waveform O4 has a voltage of −V. It flows from the terminal O3 to the coil terminal O4, and the coil B is excited. Further, since the drive waveforms O1 and O2 both have a voltage of 0 V, the transistors P1 and P2 are turned on, the transistors N1 and N2 are turned off, the drive current does not flow through the coil A, and the coil A is not excited.

Next, a high-speed rotary drive in units of 360 degrees per step of the step motor 20 by the second unit drive signal D2 will be described with reference to FIG. FIG. 11A shows the initial state of the step motor 20, and the north pole of the rotor 21 is at the stable position of 0 degrees.

FIG. 11B shows a state in which the first drive pulse SP11 is supplied to the step motor 20, and in this case, as described above, a drive current (not shown) flows from the coil terminal O4 to the coil terminal O3. The coil B is excited in the direction of the arrow. As a result, the second magnetic pole portion 22b is magnetized to the N pole, the third magnetic pole portion 22c is magnetized to the S pole, and the coil A is not excited, so that the first magnetic pole portion 22a has the same S pole as the third magnetic pole portion 22c. ..

As a result, the north pole of the rotor 21 and the south pole of the first magnetic pole portion 22a and the third magnetic pole portion 22c are attracted to each other, and the south pole of the rotor 21 and the north pole of the second magnetic pole portion 22b are attracted to each other, and the rotor 21 is counterclockwise. Rotating clockwise, the north pole of the rotor 21 rotates from a stable position of 0 degrees to a position of about 135 degrees.

Next, in FIG. 11C, when the second drive pulse SP12 is supplied, a drive current (not shown) flows from the coil terminal O1 to the coil terminal O2, and the coil A moves in the direction of the arrow, as described above. Is excited by. Similarly, a drive current (not shown) flows from the coil terminal O3 to the coil terminal O4, and the coil B is excited in the direction of the arrow (direction opposite to the coil A).

As a result, the first magnetic pole portion 22a is magnetized to the N pole, the second magnetic pole portion 22b is magnetized to the S pole, and the magnetizations of the third magnetic pole portion 22c cancel each other out and are not magnetized. As a result, the north pole of the rotor 21 and the south pole of the second magnetic pole portion 22b are attracted to each other, and the south pole of the rotor 21 and the north pole of the first magnetic pole portion 22a are attracted to each other, so that the rotor 21 is further counterclockwise without stopping. The north pole of the rotor 21 rotates to a position of about 270 degrees.

Next, in FIG. 11D, when the third drive pulse SP13 is supplied, a drive current (not shown) flows from the coil terminal O3 to the coil terminal O4, and the coil B moves in the direction of the arrow, as described above. Is excited by. As a result, the second magnetic pole portion 22b is magnetized to the S pole, the third magnetic pole portion 22c is magnetized to the N pole, and the coil A is not excited, so that the first magnetic pole portion 22a has the same N pole as the third magnetic pole portion 22c. .. As a result, the south pole of the rotor 21 and the north pole of the first magnetic pole portion 22a and the third magnetic pole portion 22c are attracted to each other, the rotor 21 further rotates counterclockwise without stopping, and the north pole of the rotor 21 is about 315. Rotate to the degree position.

After that, when the supply of the third drive pulse SP13 is completed, all the drive waveforms O1 to O4 have a voltage of 0 V, so that the coils A and B of the step motor 20 are not excited, and the first to third magnetic pole portions 22a to 22c However, the rotor 21 continues to rotate from the position where the north pole is about 315 degrees to a stable position of 360 degrees (0 degrees) without stopping, and is held at that position. The step motor 20 is rotationally driven by 360 degrees by one-step drive by the second unit drive signal D2 based on the three drive pulses SP11 to SP13.

Here, in driving the step motor 20 by the second unit drive signal D2, the magnetic field generated from the stator 22 by the third drive pulse SP13 draws the north pole of the rotor 21 to a position (second position) of about 315 degrees. Is. This position is in front of the first position in the first unit drive signal D1. Therefore, when the application of the third drive pulse SP13 is completed, the position of the north pole of the rotor 21 does not exceed 0 degrees. Further, since the rotor 21 moves to a stable position in a state where the coils A and B are not excited after the second subsequent drive pulse SP41 is output, the speed when the N pole position of the rotor 21 becomes 0 degrees. Is smaller than the first subsequent drive pulse SP40, and due to its speed, the position of the north pole of the rotor 21 does not exceed 90 degrees and reach the next stable position.

When the first unit drive signal D1 is supplied, the rotor 21 may rotate too much, but even if the rotor 21 rotates too much, the leading drive pulse SP30 supplied next causes FIG. 9B or FIG. Since the position is the same as that of the position 11 (b), there is no possibility that the north pole of the rotor 21 and the drive body connected to the north pole of the rotor 21 reach an unexpected position due to excessive rotation. On the other hand, by supplying the second unit drive signal D2, which does not have a risk of excessive rotation, as the final unit drive signal, the rotor 21 can be finally rotated as desired and the drive body can be stopped at a desired position. .. Further, the first unit drive signal D1 can rotate the rotor 21 faster, and can move the drive body at a higher speed.

[Control of step motor by detecting rotation]
Hereinafter, a method of detecting the rotation of the step motor 20 and reflecting the detection result in the driving of the step motor 20 will be described. More specifically, the motor control unit 2 controls the time for outputting the next first unit drive signal D1 or the second unit drive signal D2 based on the detected rotation of the rotor 21. In the following description, the length of the head drive pulse SP30 is changed depending on the conditions, and the lengths of the first subsequent drive pulse SP40 and the second subsequent drive pulse SP41 are fixed and predetermined. The difference in control in the head drive pulse SP30 will be mainly described.

FIG. 12 is a waveform diagram illustrating another example of the waveform generated by the head drive pulse SP30. The pulse waveforms shown by (1) to (3) in FIG. 12 show an example of a drive pulse applied to the step motor 20 when the rotor 21 is determined to rotate, that is, a head drive pulse SP30. In addition to those shown in (1) to (3), which pulse waveform is selected changes depending on the result of rotation detection. Although not shown in FIG. 12, the first subsequent drive pulse SP40 or the second subsequent drive pulse SP41 is output immediately after the first drive pulse SP30. (4) indicates the timing of applying the detection pulse CP for performing rotation detection.

In the example of FIG. 12, the length of the head drive pulse SP30 can be selected between 1 ms and 5 ms in increments of 0.25 ms. That is, the period of the head drive pulse SP30 (variable signal) changes according to the rotation of the rotor 21. The first subsequent drive pulse SP40 or the second subsequent drive pulse SP41 is output for 3.5 ms immediately after the first subsequent drive pulse SP30. The period of the first subsequent drive pulse SP40 or the second subsequent drive pulse SP41 (fixed signal) does not change. The length of the head drive pulse SP30 is selected based on the result of rotation detection. Basically, the motor control unit 2 continues to output the head drive pulse SP30 until it is determined to rotate. However, the longest length of the head drive pulse SP30 is set to 5 ms, and even if rotation is not detected by then, the first trailer drive pulse SP40 or the second trailer drive pulse SP41 is output after the head drive pulse SP30.

The detection pulse CP is a 16 μs wide pulse that is output every 0.25 ms from 0.625 ms after the output of the head drive pulse SP30 to 4.875 ms.

The length and shape of the first drive pulse SP30, the first subsequent drive pulse SP40, etc., and the output timing of the detection pulse CP in the above description are examples, and the shape and size of the step motor 20, the step motor 20, etc. It may be changed according to various configurations.

FIG. 13 is a flow chart showing an example of rotation detection and processing of the output of the head drive pulse SP30 and the first trailer drive pulse SP40. Hereinafter, control by the motor control unit 2 will be described with reference to this flow chart. The rotation detection and the control of the head drive pulse SP30 and the second successor drive pulse SP41 will not be described, but the difference between them is that the second successor drive pulse SP41 replaces the first successor drive pulse SP40 in ST7. This is the output point.

First, the pulse switching control unit 3 outputs the SP30 selection signal, and the selector 9 outputs the head drive pulse SP30 output from the head drive pulse generation circuit 61 to the driver circuit 10 (ST1). As a result, the rotor 21 of the step motor 20 starts rotating. Then, the detection pulse selection signal is output every 0.25 ms after 0.625 ms has elapsed, and the selector 9 is controlled to select the detection pulse CP output from the detection pulse generation circuit 66 and output it to the driver circuit 10. do. As a result, the pulse switching control unit 3 starts rotation detection (ST2). Based on the detection signal CS obtained as a result, the rotation detection circuit 11 outputs the determination result CK.

Here, the determination of rotation / non-rotation by the rotation detection circuit 11 will be described. FIG. 14 shows the waveforms of the induced currents generated in the coils A and B when the head drive pulse SP30 is applied, the pulses applied to the coil terminals O1 to O4, and the detection signal CS output by the detection pulse CP. It is a figure which shows.

From time 0 ms, the coil B is excited by the head drive pulse SP30. As a result, the rotor 21 starts rotating, and a positive induced current is generated in the coils A and B.

The detection pulse CP is applied so as to connect the coil A and the rotation detection circuit 11, which is a coil different from the coil to which the head drive pulse SP30 is applied. Specifically, it is applied to the transistor TP2 connected to the coil terminal O2 every 0.25 ms from 0.625 ms after the start, whereby a detection signal CS corresponding to each detection pulse CP is obtained.

As is clear from the waveform of the induced current generated in the coil A of FIG. 14, at the beginning of the rotation of the rotor 21, the induced current generated in the coil A has a positive sign and is not a very large value. Although it depends on the conditions, in the example shown here, the sign of this induced current is inverted and becomes a negative sign when about 2.5 ms has passed from the start of rotation, and a peak of the waveform showing a value above a certain level is generated. ..

The peaks of the waveform with this negative value indicate that the rotor 21 has overcome the peaks of potential and is rotating toward the target stable position. Rotation can be detected by detecting the peak of the waveform.

The detection signal CS detected from the coil terminal O2 is compared with a negative predetermined threshold value th. Then, as shown in FIG. 14, in this example, the threshold value th is not lowered from the start of rotation until 3.375 ms has elapsed, and the detection signal CS cannot be obtained, but the detection pulse CP after 3.625 ms has elapsed. Therefore, the detection signal CS below the threshold value th is obtained.

Then, in this example, since the rotation is determined by obtaining the detection signal CS twice in succession, the detection signal CS by the detection pulse CP after 3.875 ms from the start of rotation is continuously detected. At that time, the rotation detection circuit 11 determines that the rotation is rotating, and outputs the determination result CK. If the detection signal CS is not obtained twice in succession even after 4.875 ms has elapsed from the start of rotation, it is determined that the rotation is non-rotation, and the determination result CK is output.

The timing at which the continuous detection signal CS is obtained differs depending on various conditions such as the power supply voltage, the magnitude of the load, and the posture of the electronic clock 1. Further, the judgment condition is not limited to two consecutive signals, and it can be obtained once, three times or more, or when it is continuously obtained, or can be obtained within a predetermined period. The setting is arbitrary, such as whether to add the number of signals.

In FIG. 13, when the rotation detection is started, the pulse switching control unit 3 monitors the timing at which the rotation determination is obtained. That is, first, it is determined whether the detection signal CS is obtained twice within 0.875 ms from the start of rotation (ST31). When the detection signal CS is obtained twice (ST31: Y), the rotation detection is finished (ST41), the output of the detection pulse CP is stopped, and the width of the head drive pulse SP30 is set to 1 ms (ST51). As a result, the output of the head drive pulse SP30 ends in 1 ms, the first subsequent drive pulse SP40 is subsequently output to the selector 9 (ST7), and the rotation of the rotor 21 in one step ends.

When the detection signal CS is not obtained twice by the elapse of 0.875 ms from the start of rotation (ST31: N), it is next determined whether the detection signal CS is obtained twice by the elapse of 1.125 ms (ST32). When obtained (ST32: Y), rotation detection is finished (ST42), the width of the head drive pulse SP30 is set to 1.25 ms (ST53), and after the output of the head drive pulse SP30 is finished, the first successor is continued. The drive pulse SP40 is output to the selector 9 (ST7).

Similarly, when the detection signal CS is not obtained twice by 1.125 ms (ST32: N), it is determined whether the detection signal CS is obtained twice by the elapse of 1.375 ms (ST33). When obtained (ST33: Y), rotation detection is finished (ST43), the width of the head drive pulse SP30 is set to 1.5 ms (ST53), and after the output of the head drive pulse SP30 is finished, the first successor is continued. The drive pulse SP40 is output to the selector 9 (ST7).

Such processing is repeated every 0.25 ms until the detection signal CS is obtained twice, and the period of the head drive pulse SP30 is also extended by 0.25 ms. Then, when the detection signal CS is not obtained twice by the elapse of 4.625 ms from the start of rotation, it is next determined whether the detection signal CS is obtained twice by the elapse of 4.875 ms (ST3F). When obtained (ST3F: Y), rotation detection is completed (ST4F), the width of the head drive pulse SP30 is set to 5 ms (ST5F), and after the output of the head drive pulse SP30 is completed, the first subsequent drive pulse is continuously performed. The SP40 is output to the selector 9 (ST7).

Similarly, when the detection signal CS is not obtained twice within 4.875 ms from the start of rotation (ST3F: N), the width of the head drive pulse SP30 is set to 5 ms (ST5G), and the output of the head drive pulse SP30 is output. After the completion, the first subsequent drive pulse SP40 is continuously output to the selector 9 (ST7).

In the example shown here, the width of the head drive pulse SP30 is set between 1 ms and 5 ms in 5 steps in 0.25 ms increments, but this may be set coarser (or finer) or rotated. As soon as the determination is made, the output of the leading drive pulse SP30 may be stopped to output the first subsequent driving pulse SP40.

As described above, in the case of rotating 360 degrees in one step, the rotation / non-rotation of the rotor 21 can be detected, the period for applying the head drive pulse SP30 is appropriately controlled, and the power consumption is reduced. It can be reduced and driven at high speed. Further, the drive method is such that the output and rotation of the head drive pulse SP30 are detected immediately after the output of the first subsequent drive pulse SP40 (first unit drive signal D1) in the step before that. That is, when the rotor 21 is rotated too much at the time of the previous first unit drive signal D1, the width of the head drive pulse SP30 is shortened because the detection signal is obtained twice at an early timing, and conversely, the width of the previous first unit drive signal D1 is shortened. If the amount of rotation of the rotor 21 is insufficient at the time of the unit drive signal D1, the detection signal is obtained twice at a late timing, and the width of the head drive pulse SP30 becomes long. The head drive pulse SP30 plays a role of always stabilizing the rotation during high-speed driving.

[Example of chopper control of the first subsequent drive pulse]
Each of the second drive pulse SP12 and the third drive pulse SP13 included in the first subsequent drive pulse SP40 may be composed of a plurality of potentials that are intermittently switched. FIG. 15 is a waveform diagram illustrating another example of the waveform generated by the first subsequent drive pulse SP40. In the example of FIG. 15, in the second drive pulse SP12 included in the first subsequent drive pulse SP40, the drive waveforms O2 and O4 both have a voltage of −V, and the drive waveforms O2 and O4 both have a voltage of 0V. , Is switched, and one cycle of 0.25 ms is repeated. In other words, the period in which the voltage −V is applied and the period in which 0V (a voltage different from the voltage −V) is applied to the coil terminals O2 and O4 and their connection wiring are repeated. In the former state, the coils A and B are excited as shown in FIG. 9C, but in the latter state, the coils A and B are not excited. As a result, the state of FIG. 9 (b) is slowly switched to the state of FIG. 9 (c).

Further, in the third drive pulse SP13 included in the first subsequent drive pulse SP40, one cycle 0. The 25 ms cycle is repeated. In other words, in the third drive pulse SP13, the period in which the voltage-V is applied and the period in which 0V (voltage different from the voltage-V) is applied to the coil terminal O4 and its connection wiring are repeated, and the coil terminal is also used. A signal (first current signal) for applying a voltage −V (voltage for passing a current through the connection wiring) is output to O1 and its connection wiring. In the state A, the excitation as shown in FIG. 9D is performed as in the example of FIG. Further, in the state B, the coils A and B are excited so as to rotate the north pole of the rotor 21 further than 0 degrees. FIG. 16 is a diagram showing a state of excitation in the state B. In the example of FIG. 15, by repeating the excitation shown in FIG. 9D and the excitation shown in FIG. 16, the north pole of the rotor 21 rotates toward a position exceeding 0 degrees. The drive waveform shown in FIG. 15 allows the rotor 21 to rotate at even higher speeds.

[Example of chopper control of the second subsequent drive pulse]
Each of the second drive pulse SP12 and the third drive pulse SP13 included in the second subsequent drive pulse SP41 may also be composed of a plurality of potentials that are intermittently switched. FIG. 17 is a waveform diagram illustrating another example of the waveform generated by the second subsequent drive pulse SP41. The second drive pulse SP12 included in the second subsequent drive pulse SP41 is the same as the example of FIG. 15, and thus the description thereof will be omitted.

In the third drive pulse SP13 included in the second subsequent drive pulse SP41, one cycle of 0.25 ms in which the voltage of the drive waveform O4 becomes −V and the state D of the drive waveform O4 becomes 0V is switched. The cycle is repeated. In other words, in the third drive pulse SP13, a signal (first current) that repeats a period in which a voltage-V is applied and a period in which 0V (a voltage different from the voltage-V) is applied to the coil terminal O4 and its connection wiring. Signal) is applied. In the state C, the excitation as shown in FIG. 11 (d) is performed as in the example of FIG. Further, in the state D, the coils A and B are not excited. As a result, the magnetic field applied by the stator 22 to the rotor 21 at the end timing becomes weaker than in the case of the first subsequent drive pulse SP40. That is, the rotational force applied to the rotor 21 becomes weaker, and the rotor 21 rotates more slowly toward the position shown in FIG. 11D. As a result, it is possible to further suppress the occurrence of the phenomenon that the rotor 21 rotates excessively due to inertia.

The signal (second current signal) output to the coil terminal O1 in the third drive pulse SP13 of FIG. 15 does not have to be a continuous −V potential. For example, it may be a chopper pulse having a different duty ratio or period from the signal output to the coil terminal O4. Further, the duty ratio between the period in which the voltage −V is applied and the period in the second drive pulse SP12 in the second drive pulse SP12, and the period in the states A and C and the second drive pulse in the third drive pulse SP13. The duty ratio with the period of SP12 may be appropriately adjusted according to the specifications of the step motor 20 and the driving force required for the rotation of the rotor 21. The duty ratio may be different between the second drive pulse SP12 and the third drive pulse SP13, or the duty ratio may be different between the first subsequent drive pulse SP40 and the second subsequent drive pulse SP41.

[Other examples of second unit drive signal]
In the second subsequent drive pulse SP41, the magnetic field applied by the stator 22 to the rotor 21 at the end timing may be weakened by another method. FIG. 18 is a diagram showing another example of the second unit drive signal D2, and is a diagram corresponding to FIG. 10. In the example of FIG. 18, as the third drive pulse SP13, the one in which the period of the third drive pulse SP13 of the first subsequent drive pulse SP40 shown in FIG. 8 is shortened is output. In the example of FIG. 18, the third drive pulse SP13 is shorter than the case of the first unit drive signal D1. As a result, the coils A and B are excited during the period when the north pole of the rotor 21 surely exceeds the position of 270 degrees, and the supply of magnetic force is stopped before reaching the position of 0 degrees. It is possible to weaken the magnetic force applied to the rotor 21 and reduce the speed of the rotor 21 when the rotor 21 reaches the stable position of 0 degrees as compared with the first unit drive signal D1 to prevent over-rotation.

The second unit drive signal D2 is a signal in which the magnetic field applied by the stator 22 to the rotor 21 is stronger than the first unit drive signal D1 or a signal (stop pulse) in which the magnetic field is applied for a longer time than the first unit drive signal D1. May be included in. FIG. 19 is a diagram showing another example of the second unit drive signal D2, and is a diagram corresponding to FIG. 10. In the example of FIG. 19, the third drive pulse SP13 included in the second subsequent drive pulse SP41 is longer than the first subsequent drive pulse SP40. As a result, even after the north pole of the rotor 21 exceeds 0 degrees (stable position), a magnetic force is applied to the rotor 21 so as to bring the north pole of the rotor 21 close to 0 degrees as shown in FIG. 9 (d). When the application of the 3-drive pulse SP13 is completed, the north pole of the rotor 21 stabilizes at around 0 degrees. As a result, the rotation speed of the rotor 21 can be reduced and over-rotation can be prevented after the application of the third drive pulse SP13 is completed and when the north pole of the rotor 21 reaches the stable position. Instead of lengthening the time during which the third drive pulse SP13 is applied, the magnetic field applied to the rotor by the third drive pulse SP13 (the magnetic field that brings the north pole of the rotor 21 closer to 0 degrees) may be strengthened.

In the description so far, the third drive pulse SP13 included in the second subsequent drive pulse SP41 is different from the first subsequent drive pulse SP40, but the second drive pulse SP12 may also be different from each other.

FIG. 20 is a diagram showing another example of the waveform of the unit drive signal, and is a diagram corresponding to FIG. In the example of FIG. 20, unlike the examples shown in FIGS. 6, 10 and 11, not only the third drive pulse SP13 included in the second subsequent drive pulse SP41 but also the second drive pulse SP12 is also the first subsequent drive pulse SP40. It is different from the one included in. More specifically, in the second drive pulse SP12, the voltage of the drive waveform O3 becomes −V. FIG. 21 is a diagram showing another example of the operation of the step motor 20 by the second unit drive signal D2 shown in FIG. The state of the start of rotation and the state of the step motor 20 when the head drive pulse SP30 is output, which are shown in FIGS. 21 (a) and 21 (b), are the same as the examples shown in FIGS. 6 and 11. However, as shown in FIG. 21C, when the second drive pulse SP12 is output, a drive current flows from the coil terminal O1 to the coil terminal O2, and the coil A is excited in the direction of the arrow. Similarly, a drive current flows from the coil terminal O4 to the coil terminal O3, and the coil B is excited in the direction of the arrow (the same direction as the coil A). As a result, the north pole of the rotor 21 rotates toward the position of 180 degrees. Since the position where the north pole of the rotor 21 is 180 degrees is one of the stable positions, when the third drive pulse SP13 is output as compared with the examples shown in FIGS. 6, 10 and 11 (see FIG. 21 (d)). ), The rotor 21 is difficult to rotate. As a result, the north pole of the rotor 21 can be more reliably stopped at a stable position corresponding to the rotation unit as compared with the examples of FIGS. 6, 10 and 11.

FIG. 22 is a diagram showing another example of the waveform of the unit drive signal. In the example of FIG. 22, the second drive pulse SP12 included in the second subsequent drive pulse SP41 is different from the example of FIG. More specifically, in the second drive pulse SP12, the voltage of the drive waveform O2 becomes −V, and the voltage of the drive waveform O3 becomes 0. FIG. 23 is a diagram showing another example of the operation of the step motor 20 by the second unit drive signal D2 shown in FIG. The state of the start of rotation and the state of the step motor 20 when the head drive pulse SP30 is output, which are shown in FIGS. 23 (a) and 23 (b), are the same as the examples shown in FIGS. be. However, as shown in FIG. 23C, when the second drive pulse SP12 is output, a drive current flows from the coil terminal O1 to the coil terminal O2, and the coil A is excited in the direction of the arrow. Further, no current flows between the coil terminals O3 and O4, and the coil B is not excited. As a result, the north pole of the rotor 21 rotates toward a position of about 225 degrees. This position of the north pole of the rotor 21 is in front of the one shown in FIG. 11 (c) so that the rotor 21 does not rotate too much when the output of the third drive pulse SP13 is completed (see FIG. 23 (d)). Can be done. As a result, the north pole of the rotor 21 can be more reliably stopped at a stable position corresponding to the rotation unit as compared with the examples of FIGS. 6, 10 and 11.

The controls described so far can also be applied to the reverse rotation. By simply exchanging the waveform output to the coil terminal O1 and the waveform output to the coil terminal O4, and further exchanging the waveform output to the coil terminal O2 and the waveform output to the coil terminal O3, the step is performed. This is because the motor 20 can be rotated in the reverse direction.

[Second Embodiment]
Hereinafter, the differences between the second embodiment of the present invention and the first embodiment will be mainly described. In the second embodiment, the first unit drive signal D1 contains four partial pulses to rotate 360 degrees. Further, the second unit drive signal D2 includes 3 or 4 partial pulses.

FIG. 24 is a waveform diagram schematically showing an example of the first unit drive signal D1 and an operation diagram of the step motor 20 in the second embodiment. The first unit drive signal D1 shown in FIG. 24A rotates the step motor 20 by 180 degrees twice in succession, and rotates the rotor 21 by 360 degrees. As can be seen from the description in FIG. 24A, four partial pulses SP1-1, SP1-2, SP2-1 and SP2-2 are sequentially output during the period when the second unit drive signal D2 is output. .. The partial pulses SP1-1 and SP1-2 included in the first step rotate the rotor 21 by 180 degrees, and the partial pulses SP2-1 and SP2-2 included in the second step further rotate the rotor 21 by 180 degrees. .. For example, the first step corresponds to the first drive pulse SP30, and the second step corresponds to the first subsequent drive pulse SP40. Here, the signals output by the driver circuit 10 by the partial pulses SP1-1, SP1-2, SP2-1, SP2-2 are the first partial signal, the second partial signal, the third partial signal, and the fourth partial signal, respectively. Called.

In FIG. 24A, when the partial pulse SP1-1 is output, the drive waveform O3 has a voltage −V, and the other drive waveforms O1, O2, and O4 have a voltage of 0 V. As a result, a drive current flows through the coil B of the step motor 20 connected to the drive waveforms O3 and O4 and is excited. Coil A is not excited. As a result, the second magnetic pole portion 22b is magnetized to the N pole, the third magnetic pole portion 22c is magnetized to the S pole, and the first magnetic pole portion 22a becomes the same S pole as the third magnetic pole portion 22c. As a result, the rotor 21 rotates counterclockwise from the initial state shown in FIG. 24, and the north pole of the rotor 21 rotates from a stable position of 0 degrees to a position of about 135 degrees (see FIG. 24 (b)). ..

Next, when the partial pulse SP1-2 is output, the drive waveforms O2 and O3 have a voltage −V, and the drive waveforms O1 and O4 have a voltage of 0V. Then, a drive current flows through both the coil A and the coil B, and both the coil A and the coil B are excited in the direction of the arrow (same direction) in FIG. 24 (c). The first magnetic pole portion 22a and the second magnetic pole portion 22b are magnetized to the N pole, and the third magnetic pole portion 22c is magnetized to the S pole. As a result, the rotor 21 further rotates counterclockwise, and the north pole of the rotor 21 rotates to a position of 180 degrees and stands still (see FIG. 24 (c)).

Next, when the partial pulse SP2-1 is output, the drive waveform O4 has a voltage −V, and the other drive waveforms O1, O2, and O3 have a voltage of 0 V. A drive current flows through the coil B connected to the drive waveforms O3 and O4 and is excited in the direction opposite to that of the partial pulse SP1-1, and the coil A is not excited. Then, the second magnetic pole portion 22b is magnetized to the S pole, the third magnetic pole portion 22c is magnetized to the N pole, and the first magnetic pole portion 22a becomes the same N pole as the third magnetic pole portion 22c. As a result, the rotor 21 rotates counterclockwise, and the north pole of the rotor 21 rotates to a position of about 315 degrees (see FIG. 24 (d)).

Next, when the partial pulse SP2-2 is output, the drive waveforms O1 and O4 have a voltage −V, and the drive waveforms O2 and O3 have a voltage of 0V. A drive current flows through the coils A and B of the step motor 20, and both the coils A and B are excited in the direction opposite to the partial pulse SP1-2. Then, the first magnetic pole portion 22a and the second magnetic pole portion 22b are magnetized to the S pole, and the third magnetic pole portion 22c is magnetized to the N pole. As a result, the rotor 21 further rotates counterclockwise, and the north pole of the rotor 21 rotates to a position of 360 degrees (0 degrees) (see FIG. 24 (e)). That is, the rotor 21 is rotated 360 degrees by the four partial pulses.

Even in the first unit drive signal D1 shown in FIG. 24, the rotor 21 may rotate too much due to an external environmental factor or the like. In order to correspond to this, the motor control unit 2 outputs the second unit drive signal D2 as the final unit drive signal as in the first embodiment. The second unit drive signal D2 will be described below.

FIG. 25 is a waveform diagram schematically showing an example of the second unit drive signal D2 in the second embodiment. The second unit drive signal D2 shown in FIG. 25 is different from the first unit drive signal D1 in that the signal corresponding to the partial pulse SP2-2 is not output. In the example of FIG. 25, after the north pole of the rotor 21 is rotated to a position of about 315 degrees by the partial pulse SP2-1 (see FIG. 24 (d)), the coil A and the coil B are not excited. The rotor 21 continues to rotate from a position where the north pole is about 315 degrees to a stable position of 360 degrees (0 degrees), and is held at that position. For example, the first step corresponds to the first drive pulse SP30, and the second step corresponds to the second subsequent drive pulse SP41.

Also in the example of FIG. 25, the north pole of the rotor 21 is rotated only before the stable position by the magnetic force, and the coils A and B are not excited after that, so that the north pole of the rotor 21 is in the stable position corresponding to the rotation unit. The rotation speed of the rotor 21 when it reaches the limit can be reduced, and the phenomenon that the rotor 21 rotates too much can be prevented. Further, the first unit drive signal D1 can be rotated at a higher speed, and the step motor 20 can be rotated at a higher speed as a whole.

The second unit drive signal D2 may have another waveform. For example, the second unit drive signal D2 may include a signal that is applied for a shorter time or is weaker than the first unit drive signal D1. FIG. 26 is a waveform diagram schematically showing another example of the second unit drive signal D2. In the example of FIG. 26, as the partial pulse SP2-2, the one in which the period of the partial pulse SP2-2 shown in FIG. 24 is shortened is output. In the example of FIG. 26, the shortened partial pulse SP2-2 excites the coils A and B during a period in which the north pole of the rotor 21 surely exceeds the position of 270 degrees, and before reaching the position of 0 degrees. The supply of magnetic force stops. As a result, the magnetic force applied to the rotor 21 can be weakened, the speed of the rotor 21 when the rotor 21 reaches the stable position of 0 degrees can be reduced as compared with the first unit drive signal D1, and over-rotation can be prevented. ..

FIG. 27 is a diagram showing another example of the second unit drive signal D2. In the example of FIG. 27, the partial pulse SP2-2 included in the second unit drive signal D2 is longer than that of the first unit drive signal D1. As a result, even after the north pole of the rotor 21 exceeds 0 degrees (stable position), a magnetic force is applied to bring the north pole of the rotor 21 close to 0 degrees, and when the application of the partial pulse SP2-2 is completed, the rotor 21 is applied. The north pole of is stable near 0 degrees, and an effect like a stop pulse can be obtained. As a result, the rotation speed of the rotor 21 can be reduced and over-rotation can be prevented after the application of the partial pulse SP2-2 is completed and when the north pole of the rotor 21 reaches the stable position. Instead of lengthening the time for which the partial pulse SP2-2 is applied, the magnetic field applied to the rotor by the partial pulse SP2-2 (the magnetic field that brings the north pole of the rotor 21 close to 0 degrees) may be strengthened.

The configuration diagram, circuit diagram, waveform diagram, etc. shown in each embodiment of the present invention are not limited to these, and can be arbitrarily changed as long as they satisfy the gist of the present invention. For example, the step motor 20 shown in FIG. 2 and the like is a so-called 4-terminal step motor, but instead, a 3-terminal step motor as shown in Patent Document 2 may be used.

1 Electronic clock, 2 Motor control unit, 3 Pulse switching control unit, 4 Step number setting unit, 5 Step count unit, 6 Waveform generation unit, 61 First drive pulse generation circuit, 62 First subsequent drive pulse generation circuit, 63 Second Subsequent drive pulse generation circuit, 66 detection pulse generation circuit, 9 selector, 10 driver circuit, 11 rotation detection circuit, 20 step motor, 21 rotor, 22 stator, 22a 1st magnetic pole, 22b 2nd magnetic pole, 22c 3rd magnetic pole Part, 22d rotor hole, 23a, 23b insulated substrate, 24 slits, 25 constricted part, 51 dial, 52a hour hand, 52b minute hand, 52c second hand, A, B coil, O1, O2, O3, O4 coil terminal, G gate terminal , P1, P2, P3, P4, N1, N2, N3, N4, TP1, TP2, TP3, TP4 transistor, sc counter, sc0 initial value, so target step value, D1 1st unit drive signal, D2 2nd unit drive Signal, CP detection pulse, CS detection signal, CK judgment result, SP11 1st drive pulse, SP12 2nd drive pulse, SP13 3rd drive pulse, SP30 lead drive pulse, SP40 1st subsequent drive pulse, SP41 2nd subsequent drive pulse , SP1-1, SP1-2, SP2-1, SP2-2 partial pulse, th threshold.

Claims (11)

A step motor having a rotor magnetized with two or more poles, a plurality of stators that transmit magnetic force to the rotor, and a plurality of coils that generate magnetic field toward the plurality of stators.
The first unit drive signal for rotating the rotor toward a predetermined stable position and the rotation speed of the rotor at the stable position when the rotor is rotated toward the predetermined stable position are the first units. A second unit drive signal smaller than the drive signal, and a control circuit capable of selectively outputting any one of them as a unit drive signal to the plurality of coils of the step motor.
Including
When the control circuit sequentially outputs a plurality of the unit drive signals and stops the rotor at the predetermined stable position, the plurality of the unit drive signals are the first unit drive signal and the second unit. The control circuit outputs the second unit drive signal as at least the last unit drive signal including the drive signal .
The first unit drive signal generates a magnetic field from the stator that attracts one pole of the rotor to the first position at the end timing, and the second unit drive signal at the end timing, the 1 of the rotor. A magnetic field is generated from the stator that attracts the poles to a second position in front of the first position.
Drive device. A step motor having a rotor magnetized with two or more poles, a plurality of stators that transmit magnetic force to the rotor, and a plurality of coils that generate magnetic field toward the plurality of stators.
The first unit drive signal for rotating the rotor toward a predetermined stable position and the rotation speed of the rotor at the stable position when the rotor is rotated toward the predetermined stable position are the first units. A second unit drive signal smaller than the drive signal, and a control circuit capable of selectively outputting any one of them as a unit drive signal to the plurality of coils of the step motor.
Including
When the control circuit sequentially outputs a plurality of the unit drive signals and stops the rotor at the predetermined stable position, the plurality of the unit drive signals are the first unit drive signal and the second unit. The control circuit outputs the second unit drive signal as at least the last unit drive signal including the drive signal.
The second unit drive signal is at least a signal in which the magnetic field applied by the stator to the rotor is stronger than the first unit drive signal or a signal in which the magnetic field is applied for a longer time than the first unit drive signal. Including at the end
Drive braking system. In driving braking system according to claim 1,
The second unit drive signal weakens the magnetic field applied by the stator to the rotor at the end timing as compared with the first unit drive signal .
Drive braking system. A step motor with a rotor magnetized with two or more poles and
The first unit drive signal for rotating the rotor toward a predetermined stable position and the rotation speed of the rotor at the stable position when the rotor is rotated toward the predetermined stable position are the first units. A second unit drive signal smaller than the drive signal, a control circuit capable of selectively outputting any one of them as a unit drive signal to the step motor, and a control circuit.
Including
When the control circuit sequentially outputs a plurality of the unit drive signals and stops the rotor at the predetermined stable position, the plurality of the unit drive signals are the first unit drive signal and the second unit. The control circuit outputs the second unit drive signal as at least the last unit drive signal including the drive signal.
The first unit drive signal includes a first partial signal that rotates the rotor to the first rotation angle, a second partial signal that rotates the rotor to a second rotation angle larger than the first rotation angle, and a second rotation. Includes a third partial signal that rotates to a third angle of rotation that is larger than the angle, and a fourth partial signal that rotates to a fourth angle of rotation that is larger than the third angle of rotation.
The second unit drive signal does not include the fourth partial signal.
Drive device. In driving braking system according to any one of claims 1 to 4,
Further having a detection circuit for detecting the rotation of the rotor,
The control circuit controls the time to output the currently output first unit drive signal based on the detected rotation of the rotor .
Drive braking system. In driving braking system according to any one of claims 1 to 4,
At least one of the first unit drive signal and the second unit drive signal includes a variable signal whose period changes and a fixed signal which is output following the variable signal and whose period does not change .
Drive braking system. In driving braking system according to claim 5,
At least one of the first unit drive signal and the second unit drive signal is a variable signal whose period changes according to the detected rotation of the rotor, and a variable signal which is output following the variable signal and whose period changes. Not including fixed signals ,
Drive braking system. In driving braking system according to any one of claims 1 to 7,
At least one of the first unit drive signal and the second unit drive signal has a first potential different from the first potential and at least one of the plurality of wirings connected to the step motor. Includes a chopper signal that repeatedly applies the potential of 2 .
Drive braking system. In driving braking system according to claim 8,
As the chopper signal, a first current signal that repeats a first potential and a second potential different from the first potential is applied to at least one of the plurality of wirings connected to the step motor, and the plurality of chopper signals. A second current signal different from the first current signal is applied to the other one of the wirings.
Drive braking system. In driving braking system according to any one of claims 1 to 9,
The unit drive signal is larger than the first partial signal for rotating the rotor to the first rotation angle, the second partial signal for rotating the rotor to a second rotation angle larger than the first rotation angle, and the second rotation angle. Includes a third partial signal that rotates to the predetermined angle of rotation.
Drive braking system. In driving braking system according to any one of claims 1 to 10,
The unit drive signal causes the rotor to make one revolution .
Drive braking system.

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