JPH09266698A - Driving device for stepping motor, control method thereof, and timepiece - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a driver circuit capable of further reducing power to be consumed for driving a stepping motor housed in an electronic wristwatch, etc. SOLUTION: Energy, by which a rotor is moved by inertia, after a stepping motor is supplied with driving pulses is regenerated on the power supply side. Consequently, CMOSs 21, 22, 23, 24 applying driving pulses to a driving coil 2 by tuning the power of a power supply 19 on-off and a diode 25 bypassing these CMOSs and making a current flow in the opposite direction of power- supply power are installed, and the CMOSs 21 and 22 are tuned on-off in a short period after the completion of driving pulses. Accordingly, the short-circuit current of induced electromotive force generated in the driving coil 2 is tuned on-off, and larger induced voltage is obtained and energy is regenerated on the power supply side.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a step motor drive device and a control method thereof, and more particularly to a drive device and a control method thereof which can reduce the drive power of a step motor, and a timing device using the drive device. It is about.

[0002]

2. Description of the Related Art A step motor is also called a pulse motor, a stepping motor, a stepping motor or a digital motor, and is a motor driven by a pulse signal which is widely used as an actuator of a digital controller. In recent years, small electronic devices or information devices suitable for carrying have been developed, and small and lightweight step 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 time measuring device, a reference pulse is supplied from an oscillation circuit using a crystal oscillator or the like, and the reference pulse is divided into a time signal having a frequency suitable for time measurement such as 1 MHz. Then, a drive pulse is supplied to the step motor in accordance with the time signal to move the second hand or the like of the timekeeping device.

[0003]

In such a small electronic device suitable for carrying, since the power source that can be mounted is limited, in order to perform a stable operation for a long time, it is consumed by a step motor or the like. It is important to reduce the power consumed as much as possible. Further, electronic devices that are small and suitable for carrying have been integrated, and have become multifunctional in response to various needs of users. For example, a small electronic device having a timekeeping function is equipped with various functions that consume power, and the overall power consumption tends to increase. In addition, portable electronic devices have also been devised that automatically generate power using a solar cell or the like and can be freely used anywhere for a long period of time without battery replacement. Since it is difficult to obtain a large current density from the power generation system mounted on these devices, it is desired to further reduce the electric power consumed for driving the step motor.

Therefore, it is an object of the present invention to provide a drive device and a control method therefor capable of reducing power consumption by recovering a part of electric power used for driving a step motor. In particular, it is an object of the present invention to provide a drive device and a control method capable of recovering a part of electric power with a device having a simple structure and a small number of parts, which is suitable for a small and portable electronic device. To provide a power-saving type stepping motor drive device and control method applicable to a portable device such as a timekeeping device that employs a power generation system such as a solar cell that does not require disposal or replacement of batteries. It is an object.

[0005]

In the present invention, in order to realize further power saving, a part of the electric power supplied to the step motor by using the induced electromotive force generated in the drive coil of the step motor is used. I try to regenerate. That is, when the drive pulse is supplied to the step motor to rotate the rotor, the rotor does not stop immediately but moves by inertia. Since the magnetic flux density of the drive coil (stator) changes due to the movement of the rotor, induced electromotive force is generated. In the present invention, the current due to the induced electromotive force is further changed with time, and a large induced voltage is generated in the drive coil due to the change in the magnetic flux density and the change in the current so that electric energy is regenerated to a power source such as a battery. ing.
Therefore, the driving device of the present invention is a driving device that intermittently supplies a driving pulse to the driving coil of the step motor to drive the step motor, and turns on / off the driving power supplied from the power source to the driving coil. A switch means for applying a drive pulse, a bypass means for bypassing the switch means, connecting the drive coil and the power supply, and allowing a current to flow in the opposite direction of the drive power, and a drive coil with a short cycle after the drive pulse is supplied. And a short-circuiting means for short-circuiting.

According to the driving apparatus of the present invention, after the drive pulse is supplied to the drive coil by the switch means, the drive coil is short-circuited by the short-circuit means. As a result, a change in magnetic flux density due to the movement of the rotor causes a short-circuit current to flow through the drive coil. Further, the short-circuit current fluctuates rapidly by turning on and off the short-circuit means in a short cycle. Due to this change in current, a larger induced electromotive force is generated in the drive coil. When the voltage (induced voltage) due to the induced electromotive force becomes higher than the power supply voltage, a current flows through the power supply through the bypass means, the power supply such as a battery or a capacitor is charged, and the kinetic energy of the rotor is regenerated as electric energy.

A transistor switch can be used as the switch means of the driving device of the present invention, and a parasitic diode of the transistor switch can be used as the bypass means. Further, in the case of a bipolar type drive circuit in which drive power having different polarities is applied to the drive coil by the switch means and magnetic fields having different polarities are generated in the drive coil, the short-circuit means uses the switch means made of COMS or the like to drive the drive coil. It may be connected to the same pole of driving power. As described above, the driving device of the present invention can be realized with a very simple configuration without requiring a special booster circuit, and regenerates a part of the energy supplied to the step motor to consume the power required for driving the step motor. Can be reduced.

In the timekeeping device using the step motor for moving the clock hand, the present invention is applied to the drive device which intermittently supplies the drive pulse to the step motor based on the time signal output at a constant time interval. By applying, it is possible to reduce the power consumption of the timing device. Therefore,
Even in an electronic device that has a small amount of power and is suitable for carrying, it is possible to effectively utilize other functions in addition to the timekeeping function, and to extend the battery life or eliminate the need for battery replacement. You can

[0009]

BEST MODE FOR CARRYING OUT THE INVENTION

[Example of Bipolar Driving Circuit] The present invention will be described in more detail below with reference to the drawings. FIG. 1 shows an outline of a step motor control device provided with a drive circuit according to the present invention. The control device 10 of the present example is a device that can drive the two-phase step motor 1 by one-phase, two-phase, or 1-2-phase excitation. The step motor 1 is a PM type step motor, and has drive coils 2a and 2b on the stator.
Is mounted, and the rotor 5 constituted by a permanent magnet rotates inside the stator.
The control device 10 of this example includes a drive circuit 20a that supplies drive pulses to the drive coils 2a and 2b of the step motor 1.
And 20b, and an oscillator circuit 12 for outputting a reference pulse of a reference frequency using a reference oscillator source 11 such as a crystal oscillator.
A frequency dividing circuit 13 that divides the reference pulse to output a pulse having a certain number of frequencies, and a control circuit 15 that controls the drive circuits 20a and 20b based on the pulse supplied from the frequency dividing circuit 13. Furthermore, the drive circuits 20a and 2
A power source 19 for supplying the electric power of the driving pulse to 0b is provided. The drive circuits 20a and 20b of this example are bipolar drive circuits having the same configuration, and one drive circuit will be described below.

FIG. 2 shows how the current flowing through the drive coil 2 changes when a rectangular drive pulse is supplied from the drive circuit 20 to the drive coil 2. When the drive pulse is supplied and the voltage becomes high level at time t0, a current flows through the drive coil 2 to generate a magnetic field. As a result, when the rotor rotates, a counter electromotive force is generated and the current decreases. And
Even if the voltage of the drive pulse becomes low level at time t1, the current flowing through the drive coil does not become zero. After the rotor composed of permanent magnets is driven, it moves by inertia,
It vibrates before and after the stop position during the settling time when it is stopped by the non-excitation holding torque (detent torque, cogging torque). For this reason, the magnetic flux density penetrating the drive coil changes even after the drive pulse ends, so that an induced electromotive force is generated in the drive coil. When the drive pulse is turned off, the p-channel transistors P1 and P2 of the drive circuit 20 shown in FIG. 3 are turned on, so that both sides of the drive coil 2 are short-circuited, as shown in FIG. Such a current flows to the drive coil 2. Then, as it is, the current due to the induced electromotive force is consumed by the drive coil 2 and becomes Joule heat and is dissipated.
Therefore, in the present invention, this electric power is collected.

FIG. 3 shows the configuration of the drive circuit 20 of this example. As described above, the drive circuit 20 of this example has the p-channel MOS transistor (hereinafter MOS) 2
1, 22 and n-channel MOS 23, 24 are connected so as to form a bipolar drive circuit.
The electric power supplied from 9 is controlled so that drive pulses having different polarities can be alternately supplied to the drive coil 2. Such a drive circuit 20 can be easily configured by using a CMOS, etc.
It is also possible to make monolithic on one substrate.

A current is directed to each of the MOSs 21, 22, 23 and 24 from the low voltage side to the high voltage side, that is, in the direction opposite to the direction in which the current of the drive pulse using the power supply voltage flows. Diode 25 is connected in parallel. Therefore, when a high voltage opposite to that of the power supply 19 is generated in the drive coil 2, these MOS2
Regardless of the state of 1, 22, 23 and 24, the current is M
It bypasses the OSs 21, 22, 23 and 24 and flows through the diode 25. As the diode 25, a diode element may be connected in parallel with each MOS, or a diode formed on a substrate by a PN junction may be used. Furthermore, each M
It is also possible to use the parasitic diode of the OS as the bypass diode 25.

FIG. 4 shows these MOSs 21, 22, 23.
And a control signal φp1 applied to the gate electrodes of 24,
φp2, φn1 and φn2 are shown by a timing chart. The operation of the drive circuit 20 of the present example shown in FIG. 3 will be described below based on this timing chart. The control signals φp1, φp2, φn1 and φn2 are
Usually kept at a low level. Therefore, the p-channel MOSs 21 and 22 are on and the n-channel MO is
S23 and S24 are off. Therefore, the drive coil 2
There is no current flowing in and no magnetic field is generated. When control signals φp2 and φn2 become high level at time t10, p-channel MOS 22 turns off and n-channel MOS 24 turns on. As a result, as shown by the solid line in FIG.
A current flows through the channel MOS 21, the drive coil 2, and the n-channel MOS 24, and power is supplied from the power supply 19 to the drive coil 2. That is, the drive pulse is supplied from the drive circuit 20 to the drive coil 2, and the rotor is rotated by the magnetic field generated in the drive coil 2. When the control signals φp2 and φn2 become low level at time t11, the drive pulse is turned off, and the power supply from the power supply 19 to the drive coil 2 is cut off. However, since the rotor rotates due to inertia, induced electromotive force is generated in the drive coil 2. At this time, p-channel MOS2
Since 1 and 22 are on, the drive coil 2 is short-circuited, and a current due to the induced electromotive force flows through the drive coil 2 as shown by the alternate long and short dash line in FIG. When the drive pulse is stopped, the rotor moves as it is due to inertia and further vibrates around a predetermined stop position. Therefore, the magnetic flux density across the induction coil 2 also changes and vibrates. Depending on the direction of the change, the direction of the short-circuit current indicated by the alternate long and short dash line flowing in the drive coil 2 also changes.

At time t12, control signals φp1 and φp
When 2 is set to a high level, the p-channel MOSs 21 and 22 are turned off, so that no current flows in the drive coil 2. A large induced electromotive force is generated in the drive coil 2 because the current flowing in the drive coil 2 is rapidly reduced by switching the p-channel MOSs 21 and 22. When the induced voltage at this time becomes higher than the voltage of the power supply 19 including the circuit resistance and the like, the MOSs 21, 22, 23 and 24
The current flows from the drive coil 2 to the power supply 19 in reverse, via the diode 25 provided so as to bypass the drive coil 2 and connect the drive coil 2 and the power supply 19. Thereby, for example, when a battery or a capacitor is used as the power source 19, these are charged.

Next, at time t13, when the control signals φp1 and φp2 are set to low level, the p-channel MOSs 21 and 22 are turned on, so that a short-circuit current flows through the drive coil 2. The current sharply increases due to this switching operation, so that an induced electromotive force is generated in the drive coil 2 in the direction opposite to the time t12, and when the value of the induced voltage at this time exceeds the power supply voltage, the power is again supplied via the diode 25. 19 is charged. Such an operation is performed by the rotor using the drive coil
While the induced electromotive force is being induced in the motor, the mechanical kinetic energy of the rotor can be converted into electrical energy and regenerated in the power source 19 by continuing continuously until time t14, for example. As can be seen from the above, during regeneration of energy from time t11 to time t14, the control signal φp
It is desirable to turn on and off 1 and φp2 at high speed.
Therefore, in the control device 10 of the present example, the chopper circuit 16 is provided to generate the high frequency pulse of several k to several tens of k and operate the control signals φp1 and φp2.

At time t15 when the rotor is almost stopped and energy regeneration is completed, the control signals φp1 and φn1 are set to the high level. This allows p-channel MOS2
1 turns off and the n-channel MOS 23 turns on. Therefore, a current flows through the drive coil 2 in the direction opposite to that shown by the solid line in FIG. 3, and drive pulses of different polarities are supplied. Therefore, a magnetic field in the direction opposite to the time t10 is generated in the drive coil 2 to rotate the rotor. Time t16
When the control signals φp1 and φn1 become low level and the drive pulse is turned off at time t17, the rotor is almost stopped.
Until the time t11 to the time t14, the high frequency pulse supplied from the chopper circuit 16 is controlled by the control signal φp1.
And Φp2 are overlapped with and kinetic energy of the rotor is regenerated as electric energy.

As described above, in the drive circuit 20 of the present embodiment, after the drive pulse is supplied and before the next drive pulse is supplied, the drive coil is short-circuited in a short cycle to cause a large induction to the drive coil. Electric power is generated so that kinetic energy due to the inertia of the rotor can be regenerated as electric energy on the power supply side. Therefore, it is possible to regenerate a part of the energy supplied to the step motor from the power supply side to drive the step motor.
As a result, the power consumed to drive the stepper motor can be reduced. Further, by using the drive circuit of this example, even if a large amount of electric power is used to rotate the step motor, the remaining portion can be recovered, so that the step motor can be reliably driven, and power consumption can be further reduced. Can be achieved.

Further, in the drive circuit of this example, since the high frequency pulse is used to boost the voltage by the drive coil,
No complicated step-up circuit is required because the kinetic energy of the rotor is regenerated as electric energy in the power source. For example,
If a MOS parasitic diode is used as a bypass circuit, a switching MO that generates a drive pulse is used.
Energy can be regenerated by applying a high frequency pulse from the chopper circuit to the S after outputting the drive pulse. Furthermore, since the energy that has been conventionally released as Joule heat can be recovered, the effect of reducing the temperature rise of the motor can be expected.

[Example of Unipolar Drive Circuit] The present invention is not limited to the bipolar drive circuit described above, but can be applied to any circuit that intermittently supplies a drive pulse to the drive coil of the step motor. Is. FIG. 5 shows an example of a unipolar type drive circuit. The drive circuit 30 is, for example, a drive circuit for a two-phase step motor, and is representatively shown as a portion that supplies drive pulses to the first and third drive coils 3a and 3c of the stator of the step motor. The drive circuit 30 of the present example turns on and off the power supplied from the power supply 19 to bypass the switches 31a and 31c, which supply drive pulses to the drive coils 3a and 3c, and the switches 31a and 31c, respectively. And the switch 32 installed so as to short-circuit the drive coils 3a and 3c. Diodes 33a and 33c
Is installed so that a current flows in the direction opposite to the direction of the supplied power, and does not hinder the functions of the switches 31a and 31c when supplying the drive pulse. The switches 31a, 31c and 32 have control signals φs from the control circuit 15 similar to the drive circuit 20 described above.
1, φs2 and φs3. When the rotor is rotated by the drive coils 3a and 3c,
For example, the switches 31a and 31c are closed by the control signals φs1 and φs2, and the drive coils 3a and 3c are closed.
A magnetic field having a different polarity is excited in c. At this time, the switch 32 for short circuit is in an open state by the control signal φs3. When the rotor rotates, the switches 31a and 31c are opened and the switch 32 is closed by the control signals φs1, φs2 and φs3. As a result, the drive coils 3a and 3c are short-circuited, the induced electromotive force is generated by the change in the magnetic flux density caused by the movement of the rotor, and the short-circuit current flows. Therefore, similar to the above circuit, the switch 32 is turned on / off using the high frequency pulse from the chopper circuit. As a result, a high voltage induced voltage is generated in each of the drive coils 3a and 3c, and the switches 31a and 31c.
33a and 33 for bypassing each of the
drive coils 3a and 3c are connected to the power source 1 via
9, the power source 19 regenerates energy. In this example, the switch 32 for short circuit is connected to the two drive coils 3a.
And 3c are connected, but separate short-circuiting switches may be provided to short-circuit the drive coils 3a and 3c, and the short-circuiting switches may be driven by high-frequency pulses. Is.

[Example of Clocking Device] FIG. 6 shows an example of a clocking device for driving the step motor for hand movement by applying the drive circuit of the step motor according to the present invention. The timing device 8 of this example includes a step motor 40, a control device 10 that controls the step motor 40, a train wheel 50 that transmits the movement of the step motor 40, and a second hand 61 and a minute hand 62 that are moved by the train wheel 50. And an hour hand 63. The step motor 40 of this example includes a drive coil 41 that generates a magnetic force by a drive pulse supplied from the control device 10, a stator 42 that is excited by the drive coil 41, and a rotor 43 that rotates inside the stator 42. Is equipped with. This rotor 43 has a disc shape 2
The PM type (permanent magnet rotating type) one-phase step motor 40 is constituted by a pole permanent magnet.
In the stator 42, the magnetic saturation part 4 is arranged so that different magnetic poles are generated at the respective stator ends 45 and 46 around the rotor 43 by the magnetic force generated in the drive coil 41.
7 are provided. Further, in order to define the rotation direction of the rotor 43, an inner notch 48 is provided at an appropriate position on the inner circumference of the stator 42, thereby generating a cogging torque and stopping the rotor 13 at an appropriate position. I am trying.

The rotation of the rotor 43 of the step motor 40 is driven by the fifth wheel 51 meshed with the rotor 43 via a pinion.
It is transmitted to each hand by a train wheel 50 including a fourth wheel 52, a third wheel 53, a second wheel 54, a date wheel 55 and a hour wheel 56. The second hand 61 is connected to the shaft of the fourth wheel 52,
A minute hand 62 is connected to 4 and an hour hand 63 is connected to the hour wheel 56, and the time is displayed by these hands in conjunction with the rotation of the rotor 43. In the train wheel 50,
Furthermore, it is of course possible to connect a transmission system or the like (not shown) for displaying the date and the like.

The timekeeping device 8 of the present example comprises a step motor 40.
The time is displayed by rotating. Therefore, the step motor 40 is driven by the drive pulse output according to the predetermined time signal. The control device 10 of the present example for controlling the step motor 40 has substantially the same configuration as the control device including the bipolar drive circuit described above, and the drive pulse supplied to the step motor 40 has a predetermined value suitable for timing. It is supplied at time intervals. for that reason,
An oscillation circuit 12 that outputs a reference pulse of a reference frequency using a reference oscillation source 11 such as a crystal oscillator, a frequency dividing circuit 13 that divides the reference pulse and outputs a pulse of several specific frequencies, and a high frequency A chopper circuit 16 for superimposing pulses and a control circuit 15 for controlling each switch of the drive circuit 20 based on the pulse signals supplied from these circuits are provided.

Furthermore, the control device 10 of the present embodiment supplies the drive circuit 2 with electric power from the power source 19 as a drive pulse to the step motor 40 based on the control signal from the control circuit 15.
0 is provided. This drive circuit 20 is of a bipolar type using MOS transistors 21, 22, 23 and 24, and is substantially the same as the bipolar type drive circuit already described. .

Further, the control device 10 of the present example has the drive circuit 2
In the wiring that supplies the drive pulse from 0 to the drive coil 41,
A detection circuit 18 for detecting rotation / non-rotation of the rotor 43 by an induced voltage generated after supplying the drive pulse is connected, and the control circuit 15 detects the rotation / non-rotation of the rotor by a detection signal from the detection circuit 18. In the case of non-rotation, the drive pulse having a larger electric power than the normal drive pulse is supplied to the step motor 40 to surely rotate the step motor. Since the circuit is simple and can reliably determine the rotation / non-rotation of the rotor, the rotation of the rotor is often detected using an induced voltage caused by the rotation of the rotor. Since the detection circuit 18 of the present example also makes a determination using the induced voltage generated in the drive coil 11, it is necessary to separate the timing at which energy is regenerated from the drive coil 11 to the power supply and the timing at which the detection circuit 18 performs detection. is there. For this purpose, switches 17a and 17b made of p-channel MOS are provided. These MOS 17a and 1
7b is also the control signals φs7 and φs8 from the control circuit 15.
Is controlled by Of course, the method for detecting the rotation / non-rotation of the rotor is not limited to this example, and the stator 42 disclosed in Japanese Patent Publication No. 61-15384 may be used.
To detect the difference in time constants that generate magnetic flux in the
A means for detecting the rotation angle of 3 using a sensor or the like may be adopted. In addition, it may be judged by the voltage, polarity and timing generated during the regeneration of electric energy to the power source. As a result, the energy regeneration and the rotation / non-rotation of the rotor can be determined at the same timing. Can be regenerated.

Timings of supplying the control signals φp1, φp2, φn1, φn2 and φs7, φs8 to the MOSs 21, 22, 23 and 24 of the drive circuit 20 and the MOSs 17a and 17b of the detection circuit 18 are supplied from the frequency dividing circuit 13. Signals φ0, φ1, φ2, φ3 and high frequency pulses φ8k and φ1k supplied from the chopper circuit 16
It is output based on. FIG. 7 shows how these control signals are output. The timing signals φ0, φ1, φ2, and φ3 supplied from the frequency dividing circuit 13 have the same cycle, for example, a cycle signal of 1 Hz which is suitable for timing, and the timing at which the level of each signal fluctuates is changed. On the other hand, the signals φ8k and φ1k supplied from the chopper circuit 16 are signals having a short cycle. For example, the signal φ8k for energy regeneration is several k to several tens k.
Hz signal, signal φ1k for detecting rotation / non-rotation
Is a signal of several 100 Hz to several kHz.

At time t20, when the timing signal φ0 changes from the low level to the high level, the control signals φp2 and φp
n2 goes high, and the p channel M of the drive circuit 20
The OS 22 turns off and the n-channel MOS 24 turns on. Since the p-channel MOS 21 of the drive circuit 20 is on, a current flows through the p-channel MOS 21, the drive coil 41, and the n-channel MOS 24 by this, and power is supplied from the power supply 19 to the drive coil 41. That is, the drive pulse is supplied from the drive circuit 20 to the drive coil, and the rotor 43 of the step motor 40 rotates 180 degrees. When the timing signal φ2 changes from the low level to the high level at time t21, the control signal φp
2 and φn2 go low, and the drive pulse is turned off. Therefore, the power supply from the power source 19 to the drive coil 2 is cut off. However, the rotor 43 is rotating by inertia. Therefore, an induced electromotive force is generated in the drive coil 41, and the p-channel MOSs 21 and 22 are turned on, so that both ends of the drive coil 41 are short-circuited and a short-circuit current flows. Therefore, as described above, the control signal φp
When a high frequency pulse is superimposed on 1 and φp2, the short circuit current changes abruptly and a large induced voltage is generated in the drive coil 41. Therefore, a current flows from the drive coil 41 to the power supply 19 via the bypass diode 25, and the kinetic energy of the rotor 43 is regenerated as electric energy.

During the above control, the control signal φs
7 and φs8 are kept at a high level, and p-channel MOS 17a and 17b are off. Therefore, the drive pulse and voltage fluctuation during regeneration are detected by the detection circuit 18
Is not supplied. When the timing signal φ2 is inverted from the low level to the high level at time t22, the control signal φp1 is superposed with the high frequency pulse φ1k of about 1 kHz described above, and the control signal φs7 is superposed with the same high frequency pulse φ1k. . Then, the control signal φp2 is held at the low level. Therefore, the drive coil 41 has the p-channel MOSs 21 and 2 at the cycle of the high frequency pulse φ1k.
The induced voltage generated by short-circuiting by 2 is applied to the detection circuit 18 via the p-channel MOS 22 and 17a at the cycle of the high frequency pulse φ1k. Therefore,
The drive coil 41 is rotated by the rotation of the rotor after time t22.
The induced voltage generated at 1 is amplified in the cycle of the high frequency pulse φ1k and detected by the detection circuit 18 with the power supply voltage as a reference value. Then, the rotation / non-rotation of the rotor is judged from the variation pattern of the induced voltage. This detecting step is performed until time t23 when the timing signal φ3 is inverted from the low level to the high level, and one cycle of driving the step motor is completed. If it is detected that the rotor is not rotating, following these cycles,
A step of supplying a drive pulse of large power to the step motor to surely rotate the step motor is executed.

At time t24, when the timing signal φ0 changes from the high level to the low level, the cycle for rotating the next step motor is started. The control signals φp1 and φn1 are set to the high level at time t24 in accordance with the change of the timing signal φ0. This allows p-channel MOS2
1 turns off and the n-channel MOS 23 turns on. Therefore, current flows in the drive coil 41 in the direction opposite to the previous cycle, and drive pulses of different polarities are supplied.
Therefore, a magnetic field of opposite phase is generated in the stator 42 of the drive coil 41, and the rotor 43 rotates 180 degrees again. When the timing signal φ1 is inverted from the high level to the low level at time t25, the control signals φp1 and φn1 are turned to the low level and the drive pulse is turned off. Then, the high-frequency pulse φ8k is superimposed on the control signals φp1 and φp2, and the kinetic energy of the rotor is regenerated as electric energy. When the timing signal φ2 is determined from the high level to the low level at the time t26, the process shifts from energy regeneration to detection of rotation / non-rotation of the rotor, the control signal φ2 is the high frequency pulse φ1k, and the control signal φs8 is the high frequency pulse φ.
The signals obtained by inverting 1k are superimposed. As a result, similarly to the above, the induced voltage due to the rotation of the rotor is judged by the detection circuit 18 based on the power supply voltage. When the timing signal φ3 is inverted from the high level to the low level at time t27,
The cycle of driving the rotor ends. Following this,
When the rotor is not rotating, a drive pulse having a large pulse width is supplied to the step motor and rotated as described above.

In the control device 10 of this example, the control signals φp1 and φp are controlled by the control circuit 15 using the timing signals φ1 to φ3 and the high frequency pulses φ8k and φ1k.
n1, φp2, φn2, φs7 and φs8 are output, and an example of the circuit is shown in FIG. The control circuit 15 using such a logic circuit can be configured by using a switching element such as CMOS, and also can be realized by using the switching element such as CMOS including the drive circuit 20 and the bypass diode. The other circuits constituting the control device 10 of this example, such as the detection circuit 18 and the frequency dividing circuit, are also the same, and the control device 10 of this example can be formed on a semiconductor substrate by using a known IC process. is there. Therefore, the control device of the present example can be easily stored in a small-sized and portable electronic device such as an electronic wristwatch without taking up a space. Then, by using the control device of the present example, energy can be regenerated from the step motor to save the power required for driving the step motor.

According to the measurement by the inventors of the present application, in the above-mentioned time measuring device, the energy inputted to the step motor is changed by using the high frequency pulse chopped to the duty ratio of 25 to 75% and the frequency of about 4 to 8 kHz. 5
It is known that about% energy can be regenerated to the power supply side. Therefore, the power consumption can be reduced by about 5% by using the control device of this example. This measurement is
This is an effect obtained when the present invention is applied to a step motor for a timekeeping device having a one-body type stator having a highly accurate generation of counter electromotive force as much as possible. By applying the present invention to a stepping motor used for, it is possible to expect further significant power saving.

In the above example, the present invention has been described by taking a one-phase or two-phase step motor as an example, but it goes without saying that the present invention can be similarly applied to a step motor having three or more phases. is there. Further, the driving method of the step motor is not limited to the one-phase excitation method, and the driving pulse may be intermittently supplied to the step motor by the two-phase excitation method or the 1-2-phase excitation method. Further, the step motor driven by the driving device of the present invention is not limited to the PM type, and the present invention can be applied to a hybrid type step motor.

[0032]

As described above, according to the present invention, the kinetic energy due to the inertia of the rotor is converted into the induced electromotive force generated in the drive coil, and the short-circuit current flowing through the drive coil is changed to change the drive coil. Is used as a voltage boosting means to regenerate the power source. Therefore, a part of the energy supplied to the step motor can be easily regenerated without using a complicated step-up circuit, and as a result, the power consumed for driving the step motor can be reduced.

Therefore, according to the present invention, the electric power consumed for driving the step motor can be suppressed to a low level, and in recent years, a step motor driving device and a step motor driving device suitable for portable devices which have become smaller and have more functions have been provided. The control device can be provided. For example, in a portable device such as an electronic wristwatch, power consumption is increased due to the multi-functionalization, while at the same time, it is possible to eliminate battery replacement by miniaturization and by incorporating a power generation device such as a solar battery. . Therefore, by applying the present invention, it becomes possible to reliably perform timekeeping with low power consumption even in a device using a power source with a small amount of power generation, and to effectively use various functions installed in electronic wrist watches and the like. Can be utilized.

[Brief description of drawings]

FIG. 1 is a block diagram showing a configuration of a step motor control device using a drive circuit of the present invention.

FIG. 2 is a graph showing an example of an induced voltage generated by inertial motion of a rotor in a step motor.

FIG. 3 is a diagram illustrating an operation of the drive circuit shown in FIG.

4 is a timing chart showing a control signal supplied to a MOS of the drive circuit shown in FIG.

FIG. 5 is a diagram showing a unipolar drive circuit of the present invention.

FIG. 6 is a diagram showing a schematic configuration of a timing device using a drive circuit of the present invention.

7 is a timing chart showing a control signal supplied from the control circuit shown in FIG. 6 to a drive circuit.

8 is a block diagram showing a configuration example of a control circuit shown in FIG.

[Explanation of symbols]

 1-Step motor 2, 3-Drive coil 5-Rotor 10-Control device 11-Crystal oscillator 12-Oscillation circuit 13-Division circuit 15-Control circuit 16-Chopper circuit 18- -Detection circuit 19-Power supply 20, 30-Drive circuit 17, 21-24-MOS transistor 25, 33-Diode 31, 32-Switch 40-Step motor 41-Drive coil 42-Stator 43 ..Rotor 50..Wheel train 61..Second hand 62..Minute hand 63..Hour hand

 ─────────────────────────────────────────────────── ─── Continuation of front page (72) Inventor Norio Ito 3-5 Yamato 3-chome, Suwa City, Nagano Prefecture Seiko Epson Corporation

Claims (6)

[Claims] 1. A drive device for intermittently supplying drive pulses to a drive coil of a step motor to drive the step motor, wherein drive power supplied from a power supply is turned on / off to apply the drive pulse to the drive coil. At least one switch means, a bypass means for bypassing the switch means to connect the drive coil to the power supply, and allowing a current to flow in the opposite direction of the drive power; and the drive coil after the drive pulse is supplied. And a short-circuiting means for short-circuiting each other in a short cycle. 2. The step motor drive device according to claim 1, wherein the switch means is a transistor switch, and the bypass means is a parasitic diode of the transistor switch. 3. The drive device according to claim 1, wherein the drive device is a bipolar type in which the drive power of different polarities can be applied to the drive coil by the switch means, and the short-circuit means drives the switch means. A driving device for a step motor, wherein coils are connected to the same pole of the driving power. 4. The step motor drive device according to claim 3, wherein the switch means is at least one set of CMOS, and the bypass means is a parasitic diode of the CMOS. 5. A switch means for turning on / off a drive power supplied from a power source to supply a drive pulse to a drive coil of a step motor, and a bypass means for bypassing the switch means to connect the drive coil and the power source to drive the drive. A method of controlling a drive device, comprising: a bypass means for supplying a current in a reverse direction of electric power; and a short-circuit means for short-circuiting the drive coil, the step of intermittently supplying the drive pulse to the drive coil by the switch means. And a step of turning on and off the short-circuit means in a short cycle after supplying the drive pulse, the method of controlling a step motor drive device. 6. A step motor for moving a clock hand, and a drive device for intermittently supplying a drive pulse to the step motor based on a time signal output at a constant time interval, the drive device comprising: Switching means for turning on / off the driving power supplied from the power source to generate the driving pulse in the driving coil, bypassing the switching means, connecting the driving coil and the power source, and flowing a current in the opposite direction of the driving power. And a short-circuit means for short-circuiting the drive coil in a short cycle after the drive pulse is supplied.