JPH1080195A - Method for controlling stepping motor, control equipment and timer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a control method capable of reducing the electric power which is consumed for driving a stepping motor housed in a wristwatch or the like. SOLUTION: In order to drive a stepping motor, driving pulses P1 of low voltage and auxiliary driving pulses P2 of high voltage are supplied. When the stepping motor is not rotated by the driving pulses P1 of low voltage, the auxiliary driving pulses P2 of high voltage can be supplied, so that the stepping motor can be surely rotated. Thereby, the voltage of the driving pulses P1 can be set low to be a limit, and low voltage driving can be realized, so that the consumption power for driving the stepping motor can be remarkably reduced.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a control device and a control method for a stepping motor, and more particularly, to a power saving type control suitable for driving a stepping motor of an electronic timepiece by lowering a power supply voltage of a battery or the like. The present invention relates to an apparatus and a control method.

[0002]

2. Description of the Related Art A stepping motor is a pulse motor,
A stepping motor, a stepping motor, a digital motor, or the like is also called, and is a motor driven by a pulse signal that is frequently used as an actuator of a digital control device. In recent years, small electronic devices or information devices suitable for carrying have been developed, and small and lightweight stepping motors are often used as these actuators. A typical example of such an electronic device is a clock device such as an electronic timepiece and a time switch. In this timing device, a reference pulse is supplied from an oscillation circuit using a crystal oscillator or the like, and this reference pulse is frequency-divided into a time signal having a frequency suitable for timing such as 1 Hz. Then, a drive pulse is supplied to the stepping motor in accordance with the time signal, and the second hand and the like of the timekeeping device are moved.

[0003]

In these small electronic devices suitable for portable use, the power supply that can be mounted is limited, so that a stable operation for a long time is consumed by a stepping motor or the like. It is important to reduce as much power as possible. For this reason, in an electronic timepiece using a stepping motor, the pulse width of a driving pulse supplied to the stepping motor is gradually reduced, and the stepping motor is driven in a state of low power consumption. On the other hand, if the supplied driving pulse does not allow the stepping motor to rotate normally, the stepping motor is rotated with an auxiliary driving pulse with a sufficiently large pulse width and the pulse width of the driving pulse is increased, so that the stepping motor is reliably driven with the lowest possible power. I can do it.

The power consumed by a circuit element such as a CMOS used in a drive circuit of a stepping motor increases in proportion to the square of the drive voltage. Therefore, it has been considered to reduce the driving voltage to reduce power consumption. In particular, recent small and portable electronic devices include:
Integration is progressing, for example, with respect to wrist-mounted electronic timepieces, multifunctionality is progressing in response to various needs of users. Accordingly, various functions that consume power in addition to the timekeeping function are mounted, and the overall power consumption is increasing. Therefore, if the voltage of a circuit that realizes these functions can be reduced, the effect of reducing power consumption is very large. However, when the voltage is reduced, the delay time may be prolonged, and further, in the motor driving circuit, the voltage may be reduced to a voltage lower than the minimum required operating voltage for rotating the motor. If the voltage drops below the operating voltage, the motor cannot be driven even if the pulse width is increased. Therefore, it is difficult to reduce the voltage of a device such as a timing device that must drive the motor without fail in order to reduce power consumption from the viewpoint of securing reliability.

Therefore, in the present invention, by providing a control method and a control device capable of reliably driving a stepping motor even by using a low-voltage drive pulse, a time-consuming device or the like is consumed for driving the stepping motor. It is intended to further reduce power consumption. It is another object of the present invention to provide a control method and a control device capable of further reducing power consumed for driving a stepping motor in an environment in which drive pulses of a plurality of voltage levels can be set. And portable electronic devices with multifunctional power consumption are increasing,
Another object of the present invention is to provide a control device and a control method for a power saving type stepping motor applicable to a portable device employing a power generation system such as a solar cell that does not require disposal or replacement of a battery.

[0006]

According to the present invention, in order to reliably drive a stepping motor with a reduced driving pulse, the reduced driving pulse falls below the operating voltage of the stepping motor. If the stepping motor does not rotate, a step of supplying a high-voltage auxiliary drive pulse to forcibly rotate the stepping motor is provided to ensure that the stepping motor can rotate. That is, the method for controlling a stepping motor according to the present invention includes the following steps, and can be provided as a logic circuit, a control program for a microprocessor, or the like.

[0007] 1. A driving pulse of a first voltage having a first effective power is supplied to rotate the stepping motor.

[0008] 2. Detects rotation / non-rotation of the stepping motor.

3. When the stepping motor is not rotating, the stepping motor is provided with an effective power larger than the first effective power, and supplies an auxiliary drive pulse of a second voltage higher than the first voltage to rotate the stepping motor.

In the control method of the present invention, two different types of voltage are used: a low-voltage drive pulse for driving a one-step angle of a stepping motor, and a high-voltage auxiliary drive pulse for forced rotation. Since the pulse is prepared to be supplied to the stepping motor, the stepping motor can be reliably driven even if the driving pulse is reduced in voltage. That is, by adopting the control method of the present invention, the driving pulse is set to a low voltage in order to save power, and even if a situation where the stepping motor does not rotate occurs, the stepping motor is driven by a sufficiently high voltage auxiliary driving pulse. Can be reliably driven. Therefore, it is possible to reduce the voltage of the drive pulse without lowering the reliability of the control of the stepping motor, and to significantly reduce the consumed power.

The control method according to the present invention comprises: a driving means for supplying a driving pulse to the stepping motor; a control means for supplying a driving pulse having a first effective power from the driving means to the stepping motor at a predetermined timing; A power supply unit capable of supplying electric power of a plurality of voltages to the means, a detecting means for detecting rotation / non-rotation of the stepping motor, and a non-rotation of the stepping motor by a driving pulse of a first voltage having a first effective power. In this case, a second voltage higher than the first voltage is applied from the power supply unit to the stepping motor using an auxiliary control unit that supplies an auxiliary driving pulse from the driving unit to the stepping motor. be able to.

The power supply section is provided with means for increasing or decreasing the voltage, and can supply power having different voltage levels to the driving means. In particular, when the power supply unit includes a power storage unit and a step-down unit that can supply power of a plurality of voltages by stepping down an output voltage of the power storage unit, the power stored in the power storage unit is stepped down. Therefore, the power consumed for driving the stepping motor can be greatly reduced. For this reason, if the power storage means is a battery, it is possible to greatly extend the life of the power storage means. The stepping motor can be reliably driven continuously. Also, when the battery life is approaching or when the voltage of the power storage means decreases due to the inability to charge and the drive pulse voltage decreases, the voltage of the power storage means is increased only when rotation is not detected. It is also possible to supply the auxiliary driving means of the voltage to the stepping motor, and to perform control to eliminate a hand movement error or the like.

The minimum required torque for one stepping angle rotation differs depending on the individual stepping motors, the individual stepping angles of the stepping motors, and the environment in which the stepping motors are installed. Change. Therefore, it is desirable that the first effective power of the drive pulse also decreases and increases according to the rotation / non-rotation of the stepping motor. By setting a voltage different from the initial voltage to increase or decrease the effective power, a high power saving effect can be obtained. In order to adopt such a control method,
A voltage selection unit is provided which can change a voltage supplied from the power supply unit to the driving unit when the driving pulse is generated by the rotation / non-rotation of the stepping motor when the driving pulse having the first effective power is supplied. It is desirable. For example, the setting of the step-down unit of the power supply unit can be changed by the auxiliary control unit to supply power of different voltage to the driving unit.

Further, the driving pulse is composed of a plurality of sub-pulses having a narrow pulse width, and the voltage setting of a part of the plurality of sub-pulses is changed by using a voltage selection means, thereby obtaining a torque curve of the stepping motor. , The stepping motor is driven by a driving pulse having a power distribution conforming to the above, and the power consumption can be further reduced.

Further, when reducing the effective power, it is desirable to prioritize an effective lowering of the voltage in order to reduce the power consumption. On the other hand, when increasing the effective power, the voltage must be increased. Prior to this, it is desirable to increase the pulse width before the power consumption is reduced as much as possible.

Reference signal generating means for outputting a time signal at a constant time interval is provided, and the control means controls the driving means by this time signal to supply a driving pulse to the stepping motor, and to move the clock hand, A highly reliable timepiece with low power consumption can be provided.

[0017]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in more detail with reference to the drawings. FIG. 1 shows a schematic configuration of a timing device 1 according to the present invention. The timekeeping device 1 of this example includes a stepping motor 10 and the stepping motor 10.
, A wheel train 50 for transmitting the movement of the stepping motor 10, and a second hand 61, a minute hand 62 and an hour hand 63 driven by the wheel train 50. The stepping motor 10 of the present embodiment includes a drive coil 11 that generates a magnetic force by a drive pulse supplied from a control device 20, a stator 12 that is excited by the drive coil 11, and a rotor 13 that rotates inside the stator 12. It has. The rotor 13 is constituted by a disk-shaped two-pole permanent magnet, and constitutes a PM type (permanent magnet rotating type) stepping motor 10. The stator 12 is provided with a magnetic saturation portion 17 so that different magnetic poles are generated in the respective phases 15 and 16 around the rotor 13 by the magnetic force generated by the drive coil 11. In addition, an inner notch 18 is provided at an appropriate position on the inner periphery of the stator 12 in order to regulate the rotation direction of the rotor 13, thereby generating cogging torque and stopping the rotor 13 at an appropriate position. Like that.

The rotation of the rotor 13 of the stepping motor 10 is controlled by a fifth wheel 5 meshed with the rotor 13 through a pinion.
1, fourth wheel 52, third wheel 53, second wheel 54, minute wheel 5
The power is transmitted to each hand by a train wheel 50 including the wheel 5 and the hour wheel 56. A second hand 61 is connected to the axis of the fourth wheel & pinion 52, a minute hand 62 is connected to the second wheel & pinion 54, and an hour hand 63 is connected to the hour wheel & pinion 56. The hands indicate the time. It is of course possible to connect a transmission system (not shown) for displaying the date and the like to the wheel train 50.

In the timekeeping device 1 of the present embodiment, the time is displayed by the rotation of the stepping motor 10. For this purpose, a driving pulse output in accordance with a predetermined time signal is supplied to the stepping motor 10. You. The control device 20 of the present embodiment for controlling the stepping motor 10
An oscillation frequency dividing circuit 22 for outputting a reference pulse of a reference frequency or the like using a reference oscillation source 21 such as a crystal oscillator, and a pulse synthesizing circuit 23 for synthesizing pulses having different pulse widths from the reference pulse at various timings. And a control circuit 24 for selecting various pulses supplied from the pulse synthesizing circuit 23 and controlling the stepping motor 10. The pulse synthesizing circuit 23 controls the drive circuit 31 to supply a drive pulse P1 for performing a normal hand movement from the drive circuit 31 to the stepping motor 10, and controls the drive circuit 31 when the rotor 13 does not rotate to reduce the effective power. An auxiliary pulse for supplying a large auxiliary drive pulse P2 to the stepping motor 10 or a pulse for supplying a degaussing pulse PE to the stepping motor 10 via the drive circuit 31 are synthesized. Are selected by the control circuit 24 and supplied to the drive circuit 31. Further, the control device 20 of the present example includes a detection circuit 27 that detects rotation / non-rotation of the rotor 13 using a voltage or the like induced in the drive coil 11 when the rotor 13 rotates. The detection result of 27 is fed back to the control circuit 24 to control output of the auxiliary drive pulse P2 and control of the voltage or pulse width of the drive pulse P1. Therefore, in the present embodiment, the control circuit 24 has both functions of the control means and the auxiliary control means, and further controls the setting of the step-down circuit 42 to be described later so that different powers can be supplied to the drive circuit 31. ing.

The drive circuit 31 of the present embodiment comprises an n-channel MOS 33 and a p-channel MOS 3 connected in series in two rows.
2 comprises a bridge circuit. Therefore, the polarity of the control pulse applied to the gates of these MOSs 32 and 33 is
By inverting according to the step angle of 0, drive pulses P1 or auxiliary drive pulses P2 having different polarities can be supplied to the drive coil 11, and the magnetic field having different polarities is alternately generated in the stator 12 to rotate the rotor 13 in one direction. Can be rotated. Further, the control device 2 of this example
0 includes a power supply unit 40 that supplies power to the drive circuit 31. The power supply unit 40 includes a battery 41 and a battery 41.
Voltage step-down circuit 4 that can step down the voltage of
2 is provided. The step-down circuit 42 of the present example is capable of stepping down the power supply voltage by using a plurality of capacitors 43. For example, by using three step-down capacitors and one smoothing capacitor, the battery voltage V0 to V0, 2 / 3V
0 (V1 hereinafter) and 1 / 3V0 (V2 hereinafter) can be set.
Can be supplied to the drive circuit 31 based on the instruction from For this reason, in the control device 20 of the present example, these three voltage levels V0,
The drive pulses P1 of V1 and V2 and the like can be supplied to the stepping motor 10.

FIG. 2 shows a control flow for driving the stepping motor 10 by the control device 20 of this embodiment.
Based on this, the operation of the control device 20 of this example will be described. First, in step 71, it is detected whether or not a time signal indicating the passage of time has been output. In the above-described control device 20, for example, 1 Hz
Is supplied to the pulse synthesizing circuit 23 and the control circuit 24, based on which the control pulse is selected by the control circuit 24 and supplied to the drive circuit 31. Then, in step 72, the drive pulse P1 is supplied from the drive circuit 31 to the stepping motor 10 every one second, and the timer 1 is operated.

Next, at step 73, it is detected whether or not the rotor 13 has been rotated by the drive pulse P1.
In this example, the detection circuit 27 detects the induced voltage generated by the rotation of the rotor 13 to determine whether the rotor 13 is rotating or not. However, the means for detecting the rotation is not limited to this. Instead, a means for detecting a difference in time constant for generating a magnetic flux in the stator 12 or detecting a rotation angle of the rotor 13 using a sensor or the like disclosed in Japanese Patent Publication No. 61-15384 or the like is adopted. Of course it is good. The method of detecting the rotation / non-rotation of the rotor by the induced voltage according to the present embodiment is suitable for a very small stepping motor used in a timing device or the like. Since it can be performed immediately after the supply, the processing such as supplying the correction drive pulse P2 having a large effective power when the motor is not rotating can be smoothly performed.

In step 74, when the rotor 13 is not rotating, the control circuit 2
Next, an auxiliary pulse is supplied to the drive circuit 31 from the drive circuit 4, and an auxiliary drive pulse P2 having a large effective power is supplied to the stepping motor 10 from the drive circuit 31. Further, in synchronization with the timing at which the auxiliary pulse is supplied to the drive circuit 31,
The step-down circuit 42 is controlled by the control circuit 24, and the maximum voltage level V0 is supplied to the drive circuit 31. Accordingly, the driving circuit 31 supplies an auxiliary driving pulse P2 having a larger voltage than the driving pulse P1 to the stepping motor 10, so that the stepping motor 10 always rotates.

FIG. 3A shows driving pulses P1 and P2.
And the like are shown being supplied to the stepping motor 10. First, at time t1, a time signal of 1 Hz serves as a trigger, and a control signal for outputting a drive pulse P1 is supplied from the control circuit 24 to the drive circuit 31. At the same time, in this case, the control circuit 24 sets the supply voltage from the step-down circuit 42 to the minimum level voltage V2. As a result, the driving pulse P1 having the voltage V2 and the pulse width T1 is supplied to the stepping motor 10 at the time t1. At time t2 following the drive pulse P1, the control circuit 24 supplies a high-frequency chopper pulse synthesized by the pulse synthesis circuit 23, and the detection circuit 24 detects an induced voltage. If the induced voltage equal to or higher than the predetermined value is not detected, the rotor 13 is not rotating, and the control circuit 2
4 supplies an auxiliary pulse to the drive circuit 31, and outputs an auxiliary drive pulse P2 having a large effective power to the stepping motor 10.
Supplied to At this time, as described above, the control circuit 24
Since the setting of the step-down circuit 42 is changed and the voltage supplied to the drive circuit 31 is increased to the maximum level V0, the auxiliary drive pulse P2 having the pulse width Ts at the voltage V0 is supplied to the stepping motor 10.

The control device 20 of the present embodiment lowers the battery voltage V0 by using the voltage lowering circuit 42 so that the stepping motor 10 can be driven at a voltage as low as possible. Since the power consumption in the drive circuit 31 and the stepping motor 10 is proportional to the square of the voltage, the lower the voltage is, the lower the power consumption is. Further, considering that a drive pulse having the same effective power is supplied, it is possible to reduce the number of turns of the drive coil by lowering the voltage and increasing the current, so that the stepping motor itself and the timing device can be downsized. Another advantage is that the assembly cost can be reduced. However, if the voltage of the drive pulse P1 is lower than the operating voltage of the stepping motor 10, the motor 10 cannot be rotated even if the current is increased to increase the effective power. The operating voltage varies depending on the assembling conditions of the stepping motor and the environment such as the temperature at which the timekeeping device 1 is placed, the installation angle, and the like, and cannot be uniquely determined, and also fluctuates when the environment changes. .
Therefore, it is important to drive the stepping motor 10 with the drive pulse having the lowest effective power and the lowest effective power at the lowest voltage or higher in order to reduce power consumption.

For this reason, in the control device 20 of this embodiment, the voltage of the drive pulse P1 is reduced as much as possible, while, when the stepping motor 10 does not rotate,
The auxiliary drive pulse P2 having the highest voltage is supplied so that the stepping motor 10 can be reliably driven to rotate. Then, as described later, the drive pulse P gradually increases.
1 until the stepping motor 10 can rotate, and the driving pulse P1 with the minimum voltage and effective power
Thereby, the stepping motor 10 can be driven. Therefore, in the control circuit 20 of the present example, the operation of the stepping motor is guaranteed by the auxiliary drive pulse P2 even if the drive pulse P1 is reduced in voltage to reduce power consumption. As described above, by making it possible to supply two driving pulses and auxiliary driving pulses having different voltages to the stepping motor 10, it is possible to lower the voltage of the driving pulse without lowering the reliability and to reduce the power consumption. The stepping motor can be reliably driven.

When the auxiliary driving pulse P2 having a large effective power is supplied to the stepping motor 10 by the auxiliary pulse supplied from the control circuit 24, the energy when the rotor 13 of the stepping motor 10 overshoots at time t4 is subsequently reduced. A chopper pulse is supplied from the control circuit 24 to the drive circuit 31 so as to enable regeneration, and the regenerated energy is recovered by the smoothing capacitor of the step-down circuit 42. Subsequently, at time t5, a degaussing pulse PE having a polarity opposite to that of the auxiliary driving pulse P2 is supplied to the stepping motor 10 via the driving circuit 31, and the magnetization of the stator 12 is reduced. When the stepping motor 10 does not rotate due to the drive pulse P1, a series of these controls are performed in a one-second cycle.

Next, at time t11, one second after time t1, a control pulse for rotating the next stepping angle of the stepping motor 10 is supplied from the control circuit 24 to the drive circuit 31, and the drive pulse P1 is output. Supplied to Since the stepping motor 10 did not rotate with the driving pulse P1 supplied at the time t1, the driving pulse P1 having a larger effective power than the time t1 is supplied at the time t11. The control for increasing the effective power is performed as follows as shown in FIG. First, in step 75, it is determined whether or not the pulse width of the driving pulse P1 can be further increased. In this example, for example, when the pulse width is T
The control pulses having gradually increased widths of 0, T1, and T2 are combined, so that a wider pulse width T2 can be supplied to the drive pulse having the pulse width T1 at time t1. Therefore, at time t11, in step 75, step 76 for increasing the pulse width is selected, and at time t11,
11, a drive circuit 31 is supplied with the same voltage V2 as at time t1, and a drive pulse P1 having a pulse width T2 and a voltage V2 is supplied to the stepping motor 10. As described above, a lower drive pulse voltage is preferable in terms of power saving, so in the present control method, if there is room to increase the pulse width when increasing the effective power of the drive pulse, the drive pulse voltage may be increased. On the other hand, control for increasing the pulse width is preferentially performed.

At time t12, a detection chopper pulse is supplied following the drive pulse P1. Further, since rotation is not detected in the same manner as described above, an auxiliary drive pulse P2 having a voltage V0 and a pulse width Ts is supplied from time t13. The pulse is generated and supplied to the stepping motor 10. Further, following the auxiliary drive pulse P2, a regeneration pulse is supplied at time t14, and a demagnetization pulse PE is supplied at time t15.
Is also supplied.

Next, at time t21, which is one second after time t11.
Then, the next drive pulse P1 is supplied to the stepping motor 10. In the case of time t21, it is determined in step 75 of the flowchart shown in FIG. 2 that there is no room to increase the pulse width, so that the voltage level of the drive pulse is raised by one rank to voltage V1 in step 77. Therefore, in synchronization with the supply of the control pulse having the pulse width T0 from the control circuit 24 to the drive circuit 31, the step-down circuit 42 is switched by the control circuit 24, and the power of the voltage V1 is supplied to the drive circuit 31. As a result, FIG.
As shown in (a), at time t21, a drive pulse P1 having a voltage V1 and a pulse width T0 is supplied to the stepping motor 10. Following the drive pulse P1, rotation detection is performed at time t22, and the detection circuit 27 detects that the stepping motor 10 has rotated by the drive pulse P1 of the voltage V1 by the induced voltage.

When it is confirmed by the detection circuit 27 that the stepping motor 10 has rotated, the process proceeds from step 72 to step 78 in the flowchart shown in FIG.
The counter C is counted up. This counter C
Is a counter for counting the number of continuous rotations by the drive pulse P1. Next, in step 79, it is determined whether or not the number of the counter C has reached a specified number.
If the value of the counter C has not reached the prescribed number, the process returns to step 71 and waits for the output of the time signal.
The same steps as above are repeated.

In step 79, if the value of the counter C has reached the specified number of times, the driving pulse of the same effective power, that is, the driving pulse P1 of the same voltage and the same pulse width, is continuously used for the specified number of times.
Is driven. Therefore, the driving pulse P
There is a possibility that the stepping motor can be continuously driven even if the effective power is reduced. For this reason, the control device 20 of the present example performs a process of reducing the effective power of the drive pulse P1 in order to reduce power consumption. First, step 8
At 0, it is determined whether the voltage of the drive pulse P1 can be reduced. As described above, it is effective to reduce the drive voltage to reduce the power consumption. Therefore, in the control method of the present embodiment, the voltage of the drive pulse P1 is set smaller than the process of reducing the pulse width of the drive pulse P1. The process of reducing the priority is performed. Therefore, if it is determined in step 80 that there is room for lowering the voltage of the drive pulse P1,
In step 81, when the drive pulse P1 is output, the voltage of the power supplied from the step-down circuit 42 to the drive circuit 31 is reduced so that a drive pulse of a lower voltage is supplied to the stepping motor 10. On the other hand, if it is determined in step 80 that there is no room for lowering the voltage of the driving pulse P1, in step 82, the pulse width is reduced to reduce the effective power of the driving pulse P1, and the stepping motor 10 has a lower power consumption. Can be driven. After the setting for reducing the effective power of the drive pulse P1 is performed, the counter C is cleared to zero in step 83, and the measurement of the number of times the stepping motor 10 can be continuously driven by the drive pulse under the same condition is restarted.

For example, as shown in FIG. 3B, the stepping motor 10 is rotated at time t31 by the driving pulse P1 having the voltage V1 and the pulse width T1, and the result is confirmed by the detection circuit 27 at time t32. And time t3
At time t35, which is one second later, drive pulse P1 having the same voltage and the same pulse width is output. And this time t35
It is confirmed at time t36 that the stepping motor 10 has rotated again by the drive pulse P1. As a result,
If it is confirmed that the stepping motor 10 has been rotated a specified number of times continuously, the effective power of the drive pulse P1 may be reduced. Therefore, the voltage of the drive pulse P1 supplied to the stepping motor 10 at the time t41 by the next time signal is reduced from the voltage V1 to the voltage V2. Further, the stepping motor 10 is driven by the driving pulse P1 having a low effective power reduced to the voltage V2.
Is detected at time t42, the measurement of the number of continuous rotations by the driving pulse P1 of the effective power is restarted. Through such steps, the effective power of the drive pulse P1 can be reduced, and the power consumed by the control device 20 can be reduced.

In order to reduce the effective power, the driving pulse P1
When the voltage of the stepping motor 10 falls below the operable voltage of the stepping motor 10, the rotation is not detected by the detection circuit 27. In this case, as described above, the auxiliary pulse is supplied from the control circuit 24 to the drive circuit 31, the auxiliary drive pulse P2 having a high effective power and a large voltage is supplied to the stepping motor 10, and the stepping motor 10 Is rotated. As the drive pulse P1, those with large effective power are selected one after another while giving priority to increasing the pulse width, and the effective power is increased until the stepping motor 10 is rotated by the drive pulse P1. In this way, the control device 20 of this example gives priority to reducing the voltage of the drive pulse in the process of reducing the effective power after confirming the number of times the motor can be driven continuously. In the process of increasing the effective power as soon as the drive cannot be driven, priority is given to increasing the pulse width of the drive pulse. By adopting such a control method, the stepping motor 10 can be driven, and the drive pulse having the lowest voltage and pulse width of the power consumption can be quickly found. By driving the stepping motor 10 with the driving pulse, the power consumed by the control circuit 20 can be significantly reduced. Further, even if the voltage of the drive pulse P1 becomes insufficient for the purpose of low power consumption operation,
Since the auxiliary driving pulse P2 having a higher effective power than the driving pulse P1 and having a large effective power is supplied to the stepping motor 10 by the auxiliary pulse, the hand can be reliably advanced until the next time signal is output. In addition, it is possible to provide the timekeeping device 1 free from hand movement errors.

The drive pulse P1 can be formed by a plurality of sub-pulses 91, 92 and 93 having a narrow pulse width as shown in FIG. 4 instead of one rectangular pulse. The driving pulse P1 shown in FIG.
At time t52, a plurality of sub-pulses 91 forming a portion where the rotor starts to move, a plurality of sub-pulses 92 forming an intermediate region between time t52 and time t53, and further, at time t52
It is composed of a set of a plurality of sub-pulses 93 constituting a portion where the rotor after 53 has finished moving. In the drive pulse P1 having such a plurality of sub-pulses 91, 92 and 93 and having the chopper waveform, the sub-pulse 9
The ability to drive the stepping motor 10 can also be controlled by raising or lowering only the voltage of the sub-pulse 92 constituting the intermediate region of the driving pulse P1, instead of raising or lowering the voltage of the whole 1, 92 and 93. For example, FIG.
As shown in (a), the drive pulse P of the lowest voltage V2
1, the sub-pulses 91, 92 and 93 are set to the voltage V2, and the next drive pulse P1 of the voltage V1 is
As shown in (b), only the sub-pulse 92 in the intermediate region can be set to the voltage V1.

As shown in FIG. 5, the stepping motor 1
The cogging torque curve of 0 (non-excitation holding torque, detent torque) becomes maximum in the middle when rotating by one step angle of 0 to 90 degrees, whereas the cogging torque at the start of rotation and at the end of rotation is extremely high. Small. Therefore, in order to rotate the stepping motor 10, it is important to get over the intermediate region by the drive pulse P1, and for that purpose, a high-voltage pulse higher than the operating voltage is selected as the sub-pulse 92 in the intermediate region of the drive pulse P1. However, it is desirable to improve the effective power in the intermediate region. Further, by performing such sub-pulse control, the driving pulse P1 shown in FIG.
Instead of increasing the voltage of the entire driving pulse P1, only the voltage of the sub-pulse 92 in the intermediate region needs to be increased.
It is possible to minimize the increase in the effective power of the drive pulse P1. Therefore, the power consumed by the control device 20 to drive the stepping motor 10 can be further reduced.

When forming the drive pulse P1 using the sub-pulses 91, 92 and 93, when controlling the effective power of the drive pulse P1 without changing the voltage, the pulse width of the entire drive pulse P1 is increased or decreased. Instead, a pulse width control (P
WM control) can also be performed. PW for each of the front, middle and back sub-pulses 91, 92 and 93
It is also possible to perform M control.

As described above, in the control device 20 of the present embodiment, the voltage of the battery is reduced by the step-down circuit 42 so that the stepping motor 10 can be driven as the voltage of the drive pulse P1. Then, even when the stepping motor 10 cannot be driven because the voltage is too low, the control method of the present embodiment ensures that the display hand is set at a predetermined timing by the auxiliary drive pulse P2 having a voltage higher than the drive pulse P1. I can move it. Therefore, even if the voltage of the drive pulse P1 decreases, the control of the stepping motor 10 can be reliably performed. Therefore, the voltage of the drive pulse P1 can be quickly reduced to a minimum voltage at which the stepping motor 10 can be driven. The power consumed by the motor 10 can be kept very low.

Note that, in the above example, 2 is suitable for a timing device.
Although the present invention has been described by taking a phase stepping motor as an example, it goes without saying that the present invention can be similarly applied to three or more phase stepping motors. Also, instead of performing control common to each phase, it is also possible to individually adjust the drive pulse for each phase. In addition, the present invention is not limited to the one-phase excitation method of the stepping motor, and the present invention may be applied to a drive pulse rotating from a predetermined position to the next position regardless of two-phase excitation or 1-2-phase excitation. Thus, power consumption for driving the motor can be reduced. Further, the stepping motor controlled by the control method and the control device of the present invention is not limited to the PM type, and the present invention can be applied to a VR type or hybrid type stepping motor.

A step-up circuit for stepping up the power supply voltage is provided together with a step-down circuit for stepping down the power supply voltage. It is also possible to supply a boosted auxiliary driving pulse to reliably drive the stepping motor for a long period of time. Further, the voltage level prepared by the power supply unit is not limited to three levels, and it is needless to say that four or more voltage levels can be supplied. In addition, the power supply unit which can supply two voltage levels has the advantage that the circuit configuration is simplified. In this case, simple settings such as a high voltage for the auxiliary driving pulse and a low voltage for the driving pulse can be adopted. Further, the power source is not limited to a battery as in this example, and a large-capacity capacitor charged by a power generation device such as a solar battery can be used as a power source.

[0041]

As described above, in the present invention, two pulses having different voltages, that is, a driving pulse and an auxiliary driving pulse, can be supplied as driving pulses supplied to the stepping motor. . For this reason, when the stepping motor does not rotate even if the voltage of the drive pulse is lowered, the rotation of the stepping motor can be guaranteed by a high voltage auxiliary drive pulse, so that the voltage of the drive pulse is reduced to the limit in order to reduce power consumption. It becomes possible. In particular, in portable devices and the like in recent years such as timekeeping devices, power consumption has increased due to multifunctionalization. On the other hand, miniaturization and the incorporation of a power generation device such as a solar cell eliminate the need for battery replacement. I try to make it. Therefore, by adopting the control method and the control device of the present invention, it is possible to adopt the step-down means to reduce the power supply voltage and use the same as the power supply for driving the stepping motor, thereby reducing the power consumption of the entire portable device. And various functions mounted on an electronic wristwatch or the like can be effectively used.

[Brief description of the drawings]

FIG. 1 is a diagram showing a schematic configuration of a timing device storing a control device of the present invention.

FIG. 2 is a flowchart showing a control flow of a control device shown in FIG.

FIG. 3 is a timing chart showing how a drive pulse supplied from the control device shown in FIG. 1 to a stepping motor changes.

FIG. 4 is a timing chart showing an example in which a driving pulse is constituted by a sub-pulse.

FIG. 5 is a graph showing an example of a cogging torque curve of a stepping motor.

[Explanation of symbols]

 1. Timing device 10. Stepping motor 11. Driving coil 12. Stator 13. Rotor 20. Control device 21. Crystal oscillator 22. Oscillation frequency dividing circuit 23 .. Pulse synthesizing circuit 24 .. Control circuit 27 detection circuit 31 drive circuit 40 power supply unit 41 battery 42 step-down circuit 43 step-down capacitor 50 wheel train 61 second hand 62 minute hand 63 hour hand

Claims (9)

[Claims] 1. A first step of supplying a driving pulse of a first voltage having a first effective power to rotate a stepping motor, and a second step of detecting rotation / non-rotation of the stepping motor.
Wherein the stepping motor has a large effective power with respect to the first effective power when the stepping motor is not rotating, and supplies an auxiliary driving pulse of a second voltage larger than the first voltage to the stepping motor. And a third step of rotating the stepping motor. 2. The method according to claim 1, wherein the first effective power is decreased / increased by rotation / non-rotation of the stepping motor when the drive pulse having the first effective power is supplied. And a voltage different from the first voltage can be set in the fourth step. 3. The driving pulse according to claim 2, wherein
It consists of multiple sub-pulses with narrow pulse widths,
The fourth step is a stepping motor control method, wherein the setting of the voltage of some of the plurality of sub-pulses is changed. 4. The method according to claim 2, wherein in the fourth step, when decreasing the first effective power, setting a voltage lower than the first voltage is prioritized, and
A step of increasing the pulse width of the drive pulse before setting a voltage higher than the first voltage when increasing the effective power of the stepping motor. 5. A driving unit for supplying a driving pulse to the stepping motor, a control unit for supplying a driving pulse having a first effective power from the driving unit to the stepping motor at a predetermined timing, A power supply unit capable of supplying electric power of a plurality of voltages to the unit; a detecting unit for detecting rotation / non-rotation of the stepping motor; and the stepping by the driving pulse of a first voltage having the first effective power. When the motor is not rotating, the power supply unit supplies a second voltage higher than the first voltage to the driving unit, and supplies an auxiliary driving pulse larger than the first effective power to the stepping motor. A control device for a stepping motor, comprising: an auxiliary control unit. 6. The stepping motor according to claim 5, wherein the power supply unit includes a power storage unit and a step-down unit capable of supplying an electric power of a plurality of voltages by reducing an output voltage of the power storage unit. Control device. 7. The power supply unit according to claim 5, wherein the drive pulse is generated by the rotation / non-rotation of the stepping motor when the drive pulse having the first effective power is supplied. A control device for a stepping motor, comprising: a voltage selection unit capable of changing a voltage supplied to a driving unit. 8. The driving pulse according to claim 7, wherein:
It consists of multiple sub-pulses with narrow pulse widths,
The method of controlling a stepping motor, wherein the voltage selection means changes a voltage setting when generating a part of the plurality of sub-pulses. 9. A control device for a stepping motor according to claim 5, comprising: a stepping motor that moves a clock hand by the drive pulse; and a reference signal generating unit that outputs a time signal at a constant time interval. The timer according to claim 1, wherein the control unit supplies the driving pulse to the stepping from the driving unit in response to the time signal.