JP2008278686A - Stepping motor driver - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a stepping motor driver for driving a stepping motor with low noise. <P>SOLUTION: On the basis of an excitation amplitude value AMPIN different in every phase and a phase difference correction amount PHMODIN between the respective phases, specified excitation data stored in a ROM 21 is corrected to generate excitation signals of the stepping motor 11, so that the excitation signals are corrected so as to reduce a variation in rotational torque of the stepping motor 11. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a stepping motor driving apparatus, and relates to a technique for driving a stepping motor with low vibration and low noise.

  In recent years, stepping motors have been widely used for adjustments such as zoom, focus, aperture, and camera shake correction in photographing electronic devices such as digital still cameras and digital video cameras.

  Thus, when using a stepping motor in a photographing electronic device, one of the characteristics required for this is low noise. This is because the driving sound of the stepping motor may be picked up by the microphone and recorded as noise during video recording.

  There are many reasons why a stepping motor generates vibrations and driving sounds. Examples of this include uneven rotation speed and fluctuations in rotational torque, which generate vibrations and driving sounds of the stepping motor.

Conventionally, in order to suppress the vibration and driving sound of the stepping motor, the excitation signal of the stepping motor is
(1) Equal amplitude (2) The closer to a sine wave whose phase difference is 90 degrees, the better.

However, actually, even when driven by the excitation signal as described above, the vibration and driving sound of the stepping motor cannot be completely suppressed.
FIG. 1 shows a measurement example of fluctuations in rotational torque when the stepping motor is driven by a sinusoidal excitation signal having a constant amplitude and a phase shift of 90 degrees as described above. Thus, even if the stepping motor is driven by the excitation signal, fluctuations in rotational torque are generated, and vibration and driving noise are generated.

  As a stepping motor driving device for driving the stepping motor with low noise in order to satisfy the low noise property required by the photographing electronic device, for example, the following conventional techniques can be cited.

A conventional stepping motor driving apparatus as described above (for example, see Patent Document 1) will be described below.
FIG. 13 is a block diagram showing the configuration of a conventional stepping motor driving apparatus. In FIG. 13, the stepping motor driving apparatus 1 includes a clock signal generator 2, an up / down signal generator 3, a counter 4, a stepping motor 11, a pattern signal generation circuit 12, and a driver circuit 13. The pattern signal generation circuit 12 includes ROMs 5a, 5b and 6, and D / A converters 7 and 8. The driver circuit 13 includes comparators 9 and 10.

  The counter 4 is composed of an up / down counter that can count a step number corresponding to one cycle (360 degrees in electrical angle) of the stepping motor 11. The counter 4 sets the counting direction based on the up / down signal (rotation direction signal) that specifies the rotation direction of the stepping motor 11 generated by the up / down signal generator 3. The counter 4 performs a counting operation in synchronization with a clock signal that specifies the amount of rotation generated by the clock signal generator 2.

  In the ROMs 5a, 5b, and 6, predetermined excitation data for driving the stepping motor 11 is stored in advance. Excitation data read from the ROMs 5a, 5b and 6 are input to the D / A converters 7 and 8, respectively, converted from digital signals to analog signals, and input to the comparators 9 and 10 as excitation signals. Comparators 9 and 10 excite each phase of stepping motor 11 based on excitation signals from D / A converters 7 and 8, respectively.

The ROM 6 stores cosine wave amplitude data as the second phase excitation data, and the ROMs 5a and 5b store the first phase excitation data with respect to the cosine wave (with respect to the sine wave reference waveform). The amplitude data of a sine wave whose phase is shifted by a predetermined amount (the phase is delayed by an electrical angle by α) is stored. The shift angle α is determined according to various conditions of the stepping motor 11 so that the rotation amount of the stepping motor 11 for each pulse becomes uniform.
Japanese Patent Laid-Open No. 9-271199

  However, the actual stepping motor generates rotational torque fluctuation due to various reasons such as output resistance deviation of the driver circuit 13, coil winding resistance deviation, combination angle deviation of each phase, and back electromotive force unevenness due to magnetic field unevenness. To do. By merely shifting the phase difference of the excitation signals in the conventional example from the predetermined value by the shift angle α, the rotational torque fluctuation of the stepping motor generated by the current amount amplitude deviation due to the winding resistance of the coil cannot be suppressed.

  FIG. 2 shows a calculation example of the rotational torque of the stepping motor when the phase difference of the excitation signal is corrected when the winding resistance of the coil is different. The back electromotive force of the first coil and the second coil of the stepping motor is 0.7V, the excitation amplitude value is 5V, the winding resistance of the first coil is 65Ω, and the winding resistance of the second coil is 60Ω. . According to this, it can be seen that when the phase difference between the phases is corrected, the fluctuation of the rotational torque is increased, which is not effective.

  Therefore, if a plurality of factors that cause rotational torque fluctuations occur at the same time, the rotational torque fluctuation cannot be suppressed only by phase difference correction. Further, when the phase difference between the phases is deviated, the fluctuation of the rotational torque cannot be sufficiently suppressed only by correcting the phase difference of the excitation signal.

  The present invention solves the above-mentioned conventional problems, and a stepping motor driving device that can suppress vibration of the stepping motor due to fluctuations in rotational torque and realize further low noise with a simple device configuration. provide.

  In order to solve the above-described problems, the stepping motor driving apparatus of the present invention is configured to correct not only the phase difference between the phases but also the excitation amplitude value with respect to the excitation signal of the stepping motor.

  The first stepping motor driving apparatus of the present invention includes a stepping motor having a first coil and a second coil arranged with a predetermined phase difference, and each phase of the first coil and the second coil. Excitation amplitude value input means for inputting an excitation amplitude value for correcting the voltage or current value of the first coil, and a phase difference of voltage or current between the phases of the first coil and the second coil A phase difference correction amount input means for inputting a phase difference correction amount, driving each phase with the excitation amplitude value from the excitation amplitude value input means for the stepping motor, and the phase difference correction The excitation phase difference between the phases is corrected by the phase difference correction amount from the quantity input means.

The input values of the excitation amplitude value and the phase difference correction amount may be changed according to any one or more condition fluctuations among the rotation speed, load, and rotation direction of the stepping motor.
Further, a configuration may be adopted in which an input value of the excitation amplitude value and the phase difference correction amount for reducing the fluctuation amount of the rotational torque determined by the coil current and the counter electromotive force is determined.

  A second stepping motor driving device of the present invention includes a stepping motor having a first coil and a second coil arranged with a predetermined phase difference, and each phase of the first coil and the second coil. Excitation amplitude value input means for inputting an excitation amplitude value for correcting the voltage or current value of the first coil and the second coil based on the excitation amplitude value from the excitation amplitude value input means And an arithmetic circuit for calculating a phase difference correction amount for correcting the phase difference of the voltage or current between the respective phases of the stepping motor, and for each of the stepping motors with excitation amplitude values from the excitation amplitude value input means. The phase is driven, and the excitation phase difference between the phases is corrected by the phase difference correction amount from the arithmetic circuit.

  The arithmetic circuit uses any one or more of the rotation speed, load, and rotation direction of the stepping motor as a calculation variable, and the arithmetic circuit is a rotational torque fluctuation amount determined by the coil current and the counter electromotive force of the stepping motor. It is also possible to employ a configuration in which a phase difference correction amount that reduces the above is calculated.

Moreover, it is good also as a structure which changes the input value of the said excitation amplitude value by any one or more condition fluctuation | variation among the rotational speed of a stepping motor, a load, and a rotation direction.
Moreover, it is good also as a structure which inputs the excitation amplitude value which reduces the variation | change_quantity of the rotational torque decided by the coil current and back electromotive force of a stepping motor.

  Instead of the arithmetic circuit for calculating the phase difference correction amount, a table storing the phase difference correction amount associated with the input excitation amplitude value is provided, and each phase is determined by the input excitation amplitude value. It is also possible to drive and correct the excitation phase difference between the phases with the phase difference correction amount output from the table according to the input excitation amplitude value.

  A third stepping motor driving apparatus according to the present invention includes a stepping motor having a first coil and a second coil arranged with a predetermined phase difference, and between each phase of the first coil and the second coil. Phase difference correction amount input means for inputting a phase difference correction amount for correcting a phase difference of voltage or current, and based on the phase difference correction amount from the phase difference correction amount input means, the first coil and the An arithmetic circuit for calculating an excitation amplitude value for correcting the voltage or current value for each phase of the second coil, and for each of the stepping motors, the excitation amplitude value from the arithmetic circuit is The phase is driven, and the excitation phase difference between the phases is corrected by the phase difference correction amount from the phase difference correction amount input means.

  The arithmetic circuit uses any one or more of the rotation speed, load, and rotation direction of the stepping motor as a calculation variable, and the arithmetic circuit is a rotational torque fluctuation amount determined by the coil current and the counter electromotive force of the stepping motor. The excitation amplitude value for reducing the value may be calculated.

Moreover, it is good also as a structure which changes the input value of phase difference correction amount by any one or more condition fluctuation | variation among the rotational speed of a stepping motor, a load, and a rotation direction.
Alternatively, a phase difference correction amount that decreases the amount of fluctuation in rotational torque determined by the coil current and the back electromotive force of the stepping motor may be input.

  Instead of the arithmetic circuit that calculates the excitation amplitude value, it has a table that stores the excitation amplitude value associated with the input phase difference correction amount, and the excitation between each phase with the input phase difference correction amount. The phase difference can be corrected, and each phase can be driven with the excitation amplitude value output from the table in accordance with the input phase difference correction amount.

  According to a fourth stepping motor driving apparatus of the present invention, any one of a stepping motor having a first coil and a second coil arranged with a predetermined phase difference, a rotation speed, a load, and a rotation direction of the stepping motor. Calculating one or more excitation amplitude values for correcting the voltage or current value of each phase of the first coil and the second coil, using one or more of them as a calculation variable, An arithmetic circuit for calculating a phase difference correction amount for correcting a voltage or current phase difference between the phases of the second coil, and an excitation amplitude value from the arithmetic circuit for the stepping motor. Each phase is driven, and the excitation phase difference between the phases is corrected by the phase difference correction amount from the arithmetic circuit.

The arithmetic circuit may be configured to calculate an excitation amplitude value and a phase difference correction amount that reduce a fluctuation amount of a rotational torque determined by a coil current and a counter electromotive force of a stepping motor.
Instead of an arithmetic circuit for calculating the excitation amplitude value and the phase difference correction amount, a table storing the corresponding excitation amplitude value and the phase difference correction amount is provided. It is also possible to drive the phases and correct the excitation phase difference between the phases with the phase difference correction amount output from the table.

  As described above, according to the present invention, the excitation signal of the stepping motor is corrected by correcting the predetermined excitation data stored in the ROM based on the excitation amplitude value different for each phase and the phase difference correction amount between the phases. By generating the excitation signal, it is possible to correct the excitation signal so as to reduce the rotational torque fluctuation of the stepping motor.

  Therefore, with a simple device configuration, it is possible to suppress the vibration of the stepping motor due to the fluctuation of the rotational torque and realize further low noise.

Hereinafter, a stepping motor driving apparatus showing an embodiment of the present invention will be specifically described with reference to the drawings.
(Embodiment 1)
A stepping motor drive apparatus according to Embodiment 1 of the present invention will be described.

  FIG. 3 is a block diagram showing the configuration of the stepping motor driving apparatus according to the first embodiment. In FIG. 3, reference numeral 1 denotes a stepping motor driving device. The stepping motor driving apparatus 1 includes a clock signal generator 2, an up / down signal generator 3, a counter 4, a stepping motor 11, a pattern signal generation circuit 12, a driver circuit 13, an excitation amplitude value input means 23, and a phase difference correction amount input. Consists of means 24.

The clock signal generator 2 generates a clock pulse signal CLKP that ticks the step unit time of the stepping motor 11.
The up / down signal generator 3 generates a rotation direction signal MDIR that specifies the rotation direction of the stepping motor 11.

  The counter 4 counts the clock pulse signal CLKP from the clock signal generator 2 and outputs a count value STEP indicating an excitation position when the stepping motor 11 is excited. Specifically, the counter 4 is based on the clock pulse signal CLKP from the clock signal generator 2 and the rotation direction signal MDIR from the up / down signal generator 3, and the direction indicated by the rotation direction signal MDIR is the clock pulse signal CLKP. The count value STEP indicating the excitation position when the stepping motor 11 is excited is output for each predetermined number of clock pulse signals.

  Regarding the count value STEP, the concept of the excitation position in the signals for exciting the stepping motor 11 such as the sine wave and cosine wave is as follows. In other words, the count value STEP is made to correspond to a value of 0 to 255 out of 256 equal parts, and that value is used as the excitation position of the stepping motor 11.

Thus, if the count value STEP takes a value of 0 to 255, for example, when the drive signal is a sine wave, the excitation amplitude value AMPIN at an arbitrary excitation position is

Excitation amplitude value AMPIN
= (Peak value of drive signal) · sin (2π × count value STEP / 256)
... (Formula 1)

It can be expressed as

  The pattern signal generation circuit 12 includes a ROM 21 and an excitation amplitude value / phase difference correction circuit 22 and outputs an excitation signal of the stepping motor 11 based on the count value STEP from the counter 4.

  The ROM 21 stores in advance predetermined excitation data SINE for driving the stepping motor 11 and outputs excitation data SINE corresponding to the count value STEP from the counter 4.

Here, an example of the excitation data SINE stored in the ROM 21 will be described below.
The excitation data SINE is, for example, an integer in which the waveform of the corresponding drive signal is a sine wave and a cosine wave and the peak value is 255. Further, the count value STEP is assumed to divide, for example, one cycle of the excitation data SINE into 256 equal parts.

At this time, the sine wave and cosine wave data stored in the ROM 21 as the excitation data SINE are respectively for each count value STEP.

Sine wave data: 255 × sin (2π × count value STEP / 256)
Cosine wave data: 255 × cos (2π × count value STEP / 256)

All data calculated by.

Of course, the example of data stored in the ROM 21 described above does not limit the shape of the waveform of the excitation data SINE, the peak value, and the division method of one period of excitation data.
In the following description, the excitation data SINE for driving the stepping motor 11 is an excitation amplitude calculated by (Equation 1) according to, for example, a count value STEP in a sine wave and a cosine wave having the same period as the amplitude. Value AMPIN, but other waveforms such as triangular wave, trapezoidal wave, sine wave with added harmonics are different from sine wave, phase difference is not 90 degrees, or mutual amplitude is Even unequal waveforms do not depart from the spirit of the present invention.
(Details of excitation amplitude value / phase difference correction circuit 22)
The excitation amplitude value / phase difference correction circuit 22 receives excitation data SINE from the ROM 21 and receives excitation amplitude values AMPIN of different voltages or currents for each phase from the excitation amplitude value input means 23. The excitation amplitude value AMPIN is composed of an excitation amplitude value AMPIN1 of the first coil and an excitation amplitude value AMPIN2 of the second coil. The excitation amplitude value / phase difference correction circuit 22 corrects the amplitude of the sine wave and cosine wave for each phase of the excitation data SINE based on the excitation amplitude value AMPIN.

  The excitation amplitude value / phase difference correction circuit 22 receives the phase difference correction amount PHMODIN between the phases from the phase difference correction amount input means 24, and based on PHMODIN, calculates the phase difference between the phases of the excitation data SINE from a predetermined amount. to correct.

FIG. 4 shows a configuration block diagram of the excitation amplitude value / phase difference correction circuit 22. The excitation amplitude value / phase difference correction circuit 22 includes multipliers 25 and 26 and a phase adjustment circuit 27.
The phase adjustment circuit 27 receives the phase difference correction amount PHMODIN and the excitation data SINE, corrects the phase difference between the phases of the excitation data SINE according to the phase difference correction amount PHMODIN, and the first coil excitation data SINE1 and the first data The excitation data SINE2 of the second coil is generated.

  The multiplier 25 corrects the excitation amplitude value of the excitation data SINE1 of the first coil in accordance with the excitation amplitude value AMPIN1 of the first coil, and generates an excitation signal of the first coil. The multiplication unit 26 corrects the excitation amplitude value of the excitation data SINE2 of the second coil in accordance with the excitation amplitude value AMPIN2 of the second coil, and generates an excitation signal of the second coil.

  FIG. 5 shows another configuration block diagram of the excitation amplitude value / phase difference correction circuit 22. In this configuration, the excitation data SINE includes excitation data SINE1 for the first coil and excitation data SINE2 for the second coil.

  The multiplier 25 corrects the excitation amplitude value of the excitation data SINE1 of the first coil in accordance with the excitation amplitude value AMPIN1 of the first coil, and generates an excitation signal of the first coil. The multiplication unit 26 corrects the excitation amplitude value of the excitation data SINE2 of the second coil in accordance with the excitation amplitude value AMPIN2 of the second coil, and generates an excitation signal of the second coil. The phase adjustment circuit 27 receives the phase difference correction amount PHMODIN and the excitation signal output from the multiplication unit 26 as input, and generates an excitation signal in which the phase of the excitation signal of the second coil is corrected according to the phase difference correction amount PHMODIN. .

For the phase adjustment circuit 27 of the excitation amplitude value / phase difference correction circuit 22, the following connection method can be used in addition to those shown in FIGS. 4 and 5.
(1) The excitation data SINE1 is input, and the phase of the excitation data of the first coil is corrected according to the phase difference correction amount PHMODIN.
(2) The excitation data SINE2 is input, and the phase of the excitation data of the second coil is corrected according to the phase difference correction amount PHMODIN.
(3) The excitation signals output from the multipliers 25 and 26 are input, and the phase difference between the excitation signal of the first coil and the excitation signal of the second coil is corrected according to the phase difference correction amount PHMODIN.
(4) The excitation signal output from the multiplication unit 25 is input, and the phase of the excitation signal of the first coil is corrected according to the phase difference correction amount PHMODIN.

The excitation data SINE corrected by the excitation amplitude value / phase difference correction circuit 22 is delivered to the driver circuit 13 as an excitation signal of the stepping motor 11.
(Details of excitation amplitude value input means 23)
The excitation amplitude value AMPIN output by the excitation amplitude value input means 23 is an excitation amplitude value for each phase of the stepping motor 11, and examples of the input method include the following method.
(1) Ratio of excitation amplitude value of coil 1 and coil 2 to predetermined excitation amplitude value (2) Ratio of excitation amplitude value of coil 1 and coil 2 and absolute value of excitation amplitude value of one coil (3 ) Absolute value of excitation amplitude value of coil 1 and coil 2 (4) Difference of excitation amplitude value of coil 1 and coil 2 from predetermined excitation amplitude value (5) Difference of excitation amplitude value of coil 1 and coil 2 , Absolute value of excitation amplitude value of one coil (details of phase difference correction amount input means 24)
The phase difference correction amount PHMODIN output from the phase difference correction amount input unit 24 is a phase difference correction amount between the phases of the stepping motor 11. Examples of the input method include the following methods.
(1) Phase difference correction amount is specified by time (2) Phase difference correction amount is specified by electrical angle (3) Phase difference correction amount is specified by the number of pulses of clock pulse signal CLKP Excitation amplitude value AMPIN and phase difference correction amount PHMODIN 6 shows a conceptual diagram of how the excitation signal for driving each phase of the stepping motor 11 is corrected. In FIG. 6, with respect to the excitation signals of the first coil and the second coil of the stepping motor 11, the phase difference between the phases is corrected to be larger than 90 degrees, and the excitation amplitude value of the second coil is that of the first coil. It is corrected to a larger value.

  In FIG. 6, the phase of the first coil of the stepping motor 11 is advanced with respect to the phase of the second coil. This is the phase of the first coil and the second coil when the present invention is implemented. It does not limit the relationship.

The driver circuit 13 drives the stepping motor 11 based on the excitation signal from the excitation amplitude value / phase difference correction circuit 22.
The excitation amplitude value AMPIN and the phase difference correction amount PHMODIN input to the pattern signal generation circuit 12 from the excitation amplitude value input unit 23 and the phase difference correction amount input unit 24 are among the rotation speed, load, and rotation direction of the stepping motor 11. It is good also as a structure which changes with any one or more condition changes.

  Further, the excitation amplitude value input means 23 and the phase difference correction amount input means 24 obtain the excitation amplitude value AMPIN and the phase difference correction amount PHMODIN that reduce the fluctuation amount of the rotational torque determined by the coil current and the counter electromotive force of the stepping motor 11. The pattern signal generation circuit 12 can be input.

As a method for determining the excitation amplitude value AMPIN and the phase difference correction amount PHMODIN for reducing the fluctuation amount of the rotational torque in the excitation amplitude value input means 23 and the phase difference correction amount input means 24, for example, the following method can be cited. .
(1) The rotational torque of the stepping motor 11 is measured, and an excitation amplitude value AMPIN and a phase difference correction amount PHMODIN that reduce the fluctuation amount of the rotational torque are selected.
(2) The drive sound of the stepping motor 11 is measured, and the excitation amplitude value AMPIN and the phase difference correction amount PHMODIN for reducing the drive sound are selected.
(3) The vibration of the stepping motor 11 is measured, and the excitation amplitude value AMPIN and the phase difference correction amount PHMODIN for reducing the vibration are selected.

  As a specific input method of the excitation amplitude value AMPIN and the phase difference correction amount PHMODIN for reducing the fluctuation amount of the rotational torque of the stepping motor 11, one of the first coil and the second coil of the stepping motor 11 is selected. When the excitation amplitude value is larger than the excitation amplitude value of the other coil, the phase difference correction amount PHMODIN is input so that the mutual phase difference of the excitation signals becomes smaller than the predetermined phase difference. When an excitation amplitude value smaller than the excitation amplitude value of the other coil is input, there is a method of inputting a phase difference correction amount PHMODIN that makes the mutual phase difference of excitation signals larger than a predetermined phase difference.

An example of a specific correction method for reducing the fluctuation amount of the rotational torque of the stepping motor 11 by the above method will be described below.
First, the back electromotive force of the first coil and the second coil is 0.7 V, the excitation amplitude value is 5 V, the winding resistance of the coil is 65 Ω, and the phase difference between the first coil and the second coil is 90 degrees. , And the phase of the second coil is advanced from the phase of the first coil. At this time, as shown in FIG. 7, when the phase difference correction amount PHMODIN is adjusted, it can be seen that the fluctuation range of the rotational torque is minimized by the phase difference correction amount of −0.27 radians. However, the adjustment of only the phase difference correction amount does not mean that the torque fluctuation becomes zero.

  Next, with the phase difference correction amount of −0.27 radians being input, the excitation amplitude amount of the first coil was set to 5 V, and the excitation amplitude value of the second coil was changed. At this time, as can be seen from FIG. 8, it can be seen that the fluctuation range of the rotational torque can be suppressed to substantially zero by adjusting the excitation amplitude value of the second coil to 4.6V.

  Next, it is assumed that the phase difference between the first coil and the second coil is arranged to be narrowed from 90 degrees to π / 10 radians. At this time, by correcting the phase difference correction amount to 0.24 radians and the excitation amplitude value of the second coil to 5.2 V, the amount of fluctuation in the rotational torque of the stepping motor 11 can be suppressed to substantially zero.

  From the above calculation results, when the phase difference between the phases of the stepping motor 11 is deviated from 90 degrees, the excitation amplitude value of the phase in which the phase difference of the excitation signal is corrected so as to decrease and the phase is advanced. The amount of rotation torque fluctuation can be suppressed by correcting the excitation signal so that the phase difference of the excitation signal is increased or by correcting the excitation signal so that the excitation amplitude value of the phase that is advanced is increased. I understand that I can do it.

The correction method has been described only for the case where the phase difference of the coil is deviated from 90 degrees. However, for example, fluctuations in the rotational torque of the stepping motor 11 that occurs in the following cases should also be corrected according to the present invention. The relationship shown in FIG. 7 and FIG. 8 is shown and can be suppressed.
(1) When the output resistance of the driver circuit 13 or the winding resistance of the coil of the stepping motor 11 is different in each phase, and when each phase is driven by an excitation signal having the same amplitude, the amount of current is different.
(2) When the waveform shape and amplitude value of the back electromotive force of each phase of the stepping motor 11 are different.
(3) When the phase difference of the coil of the stepping motor 11 is deviated from 90 degrees, when the current amount of each phase is different, or when the waveform shape or amplitude value of the back electromotive force of each phase is different When two or more occur simultaneously.

  FIG. 9 shows an example in which the driving sound is measured when the phase difference / excitation amplitude value correction is applied to an actual stepping motor and driven by a 105 Hz sinusoidal excitation signal. The graph of FIG. 9A is the spectrum of the drive sound of the stepping motor 11 when correction is not performed, and the graph of FIG. 9B is the spectrum of the drive sound when correction is performed. As can be seen from FIG. 9, it can be seen that the driving sound of the second harmonic and the fourth harmonic of the excitation signal can be reduced by about 10 dB.

With the above configuration, the torque fluctuation of the stepping motor 11 can be suppressed by adjusting the excitation amplitude amount AMPIN and the phase difference correction amount PHMODIN.
(Embodiment 2)
A stepping motor drive apparatus according to Embodiment 2 of the present invention will be described.

  FIG. 10 is a block diagram showing the configuration of the stepping motor driving apparatus according to the second embodiment. The portions corresponding to the first embodiment shown in FIG. Also, the description of the same parts as those in the first embodiment shown in FIG. 3 is omitted.

  The stepping motor driving apparatus 1 in this embodiment includes a clock signal generator 2, an up / down signal generator 3, a counter 4, a stepping motor 11, a pattern signal generation circuit 12, a driver circuit 13, and an excitation amplitude value input means 23. Composed.

The pattern signal generation circuit 12 includes a ROM 21, an excitation amplitude value / phase difference correction circuit 22, and a phase difference correction amount calculation circuit 28.
The phase difference correction amount calculation circuit 28 calculates the phase difference correction amount PHMODIN based on the excitation amplitude value AMPIN from the excitation amplitude value input means 23.

Here, an example of a method of calculating the phase difference correction amount PHMODIN in the phase difference correction amount calculation circuit 28 will be described.
As an example of a method of calculating the phase difference correction amount PHMODIN, there is a method of obtaining the phase difference correction amount PHMODIN that minimizes the ripple component in the total torque TTOTAL as described below.

TTOTAL = TA + TB (Formula 2)

However, TA = IA × BEMFA: Torque by coil A TB = IB × BEMFB: Torque by coil B IA = (VINA−BEMFA) / R: Current of coil A IB = (VINB−BEMFB) / R: Current of coil B VINA = VA × sin (2π × count value STEP / 256): Coil A applied voltage VINB = VB × cos (2π × count value STEP / 256 + PHMODIN): Coil B applied voltage BEMFA = EA × sin (2π × count value STEP / 256 + π / 2): Coil A counter electromotive force BEMFB = EB × cos (2π × count value STEP / 256 + π / 2): Coil B counter electromotive force R: Winding resistance VA, VB: Applied voltage peak value, excitation amplitude value AMPIN EA, EB: Back electromotive force peak value

The above (Equation 2) is merely an example of an approximate expression, and even if there are other approximation methods and parameters, it is necessary to determine the phase difference correction amount PHMODIN that minimizes the torque ripple component. There is no change.

  In the phase difference correction amount calculation circuit 28, any one or more of the rotation speed, load, and rotation direction of the stepping motor 11 is used as a calculation variable, and the phase difference correction amount calculation circuit 28 is opposite to the coil current of the stepping motor 11. The phase difference correction amount PHMODIN for reducing the amount of fluctuation in rotational torque determined by the electromotive force can be calculated.

  Further, the excitation amplitude value AMPIN input from the excitation amplitude value input means 23 to the pattern signal generation circuit 12 is changed according to any one or more condition fluctuations among the rotation speed, load, and rotation direction of the stepping motor 11. It can also be set as a simple structure.

  Further, the excitation amplitude value AMPIN input from the excitation amplitude value input means 23 to the pattern signal generation circuit 12 is an input value for reducing the amount of fluctuation of the rotational torque determined by the coil current of the stepping motor 11 and the counter electromotive force. It can also be set as a simple structure.

  In the present embodiment, the stepping motor driving apparatus 1 having the phase difference correction amount calculation circuit 28 for calculating the phase difference correction amount PHMODIN has been described. However, instead of the phase difference correction amount calculation circuit 28, (Equation 2 ) Is stored as a table with the phase difference correction amount PHMODIN associated with the excitation amplitude value AMPIN input based on the arithmetic expression shown in FIG. 3), and each phase is driven by the input excitation amplitude value AMPIN. The configuration may be such that the excitation phase difference between the phases is corrected by the phase difference correction amount PHMODIN output from the table in accordance with the excitation amplitude value AMPIN.

  As an input method of the excitation amplitude value AMPIN for reducing the fluctuation amount of the rotational torque of the stepping motor 11 and a calculation method of the phase difference correction amount PHMODIN, the first coil of the stepping motor 11 is based on the calculation formula shown in (Formula 2). When the excitation amplitude value of one coil is greater than the excitation amplitude value of the other coil, the mutual phase difference of the excitation signals is adjusted so as to be smaller than a predetermined phase difference. When the phase difference correction amount PHMODIN is calculated and the excitation amplitude value of one coil is smaller than the excitation amplitude value of the other coil, the phase difference correction is such that the mutual phase difference of the excitation signals is larger than the predetermined phase difference. There is a method of calculating the quantity PHMODIN.

By the above method, the rotational torque fluctuation amount of the stepping motor 11 is reduced in the same manner as in the calculation shown in the first embodiment.
With the above configuration, as in the case of the first embodiment, the amount of fluctuation in the rotational torque of the stepping motor 11 can be reduced, and the driving sound of the stepping motor 11 can be reduced.
(Embodiment 3)
A stepping motor drive apparatus according to Embodiment 3 of the present invention will be described.

  FIG. 11 is a block diagram showing the configuration of the stepping motor driving apparatus according to the third embodiment. The portions corresponding to the first embodiment shown in FIG. Also, the description of the same parts as those in the first embodiment shown in FIG. 3 is omitted.

  The stepping motor driving apparatus 1 in this embodiment includes a clock signal generator 2, an up / down signal generator 3, a counter 4, a stepping motor 11, a pattern signal generation circuit 12, a driver circuit 13, and a phase difference correction amount input means 24. Consists of

The pattern signal generation circuit 12 includes a ROM 21, an excitation amplitude value / phase difference correction circuit 22, and an excitation amplitude value calculation circuit 29.
The excitation amplitude value calculation circuit 29 calculates the excitation amplitude value AMPIN based on the phase difference correction amount PHMODIN from the phase difference correction amount input means 24 based on the calculation formula shown in (Expression 2).

  In the excitation amplitude value calculation circuit 29, any one or more of the rotation speed, load, and rotation direction of the stepping motor 11 is used as a calculation variable, and the excitation amplitude value calculation circuit 29 counteracts the coil current of the stepping motor 11 and the back electromotive force. The excitation amplitude value AMPIN for reducing the fluctuation amount of the rotational torque determined by the electric power can be calculated.

  Further, the phase difference correction amount PHMODIN input from the phase difference correction amount input means 24 to the pattern signal generation circuit 12 is changed by any one or more condition fluctuations among the rotation speed, load, and rotation direction of the stepping motor 11. It can also be set as such.

  Further, the phase difference correction amount PHMODIN input from the phase difference correction amount input means 24 to the pattern signal generation circuit 12 is an input for reducing the amount of fluctuation of the rotational torque determined by the coil current of the stepping motor 11 and the counter electromotive force. It can also be set as such a structure.

  In the present embodiment, the stepping motor driving apparatus 1 having the excitation amplitude value calculation circuit 29 for calculating the excitation amplitude value AMPIN has been described. However, instead of the excitation amplitude value calculation circuit 29, the following expression (2) is given. The excitation amplitude value AMPIN associated with the phase difference correction amount input based on the arithmetic expression is stored as a table, and the excitation phase difference between the phases is corrected with the input phase difference correction amount PHMODIN. A configuration may be adopted in which each phase is driven by the excitation amplitude value AMPIN output from the table in accordance with the phase difference correction amount PHMODIN.

  As a method for inputting the phase difference correction amount PHMODIN for reducing the fluctuation amount of the rotational torque of the stepping motor 11 and a method for calculating the excitation amplitude value AMPIN, the mutual excitation signal of the stepping motor 11 is calculated based on the calculation formula shown in (Formula 2). When the phase difference correction amount PHMODIN is input so that the phase difference of the first coil becomes smaller than the predetermined phase difference, the excitation amplitude value of one of the first coil and the second coil is the excitation amplitude of the other coil. When the excitation amplitude value AMPIN is calculated so as to be larger than the value, and the phase difference correction amount PHMODIN is input so that the mutual phase difference of the excitation signals becomes larger than a predetermined phase difference, the first coil and the first coil Among the two coils, the excitation amplitude value AMPIN is calculated so that the excitation amplitude value of one coil is smaller than the excitation amplitude value of the other coil. There is a law.

By the above method, the rotational torque fluctuation amount of the stepping motor 11 is reduced in the same manner as in the calculation shown in the first embodiment.
With the above configuration, as in the case of the first embodiment, the amount of fluctuation in the rotational torque of the stepping motor 11 can be reduced, and the driving sound of the stepping motor 11 can be reduced.
(Embodiment 4)
A stepping motor drive apparatus according to Embodiment 4 of the present invention will be described.

  FIG. 12 is a block diagram showing the configuration of the stepping motor driving apparatus according to the fourth embodiment. The portions corresponding to the first embodiment shown in FIG. Also, the description of the same parts as those in the first embodiment shown in FIG. 3 is omitted.

  The stepping motor driving apparatus 1 in this embodiment includes a clock signal generator 2, an up / down signal generator 3, a counter 4, a stepping motor 11, a pattern signal generation circuit 12, and a driver circuit 13.

The pattern signal generation circuit 12 includes a ROM 21, an excitation amplitude value / phase difference correction circuit 22, and an excitation amplitude value / phase difference correction amount calculation circuit 30.
The excitation amplitude value / phase difference correction amount calculation circuit 30 uses one or more of the rotation speed, load, and rotation direction of the stepping motor 11 as a calculation variable, based on the calculation formula shown in (Formula 2). An excitation amplitude value AMPIN and a phase difference correction amount PHMODIN are calculated.

As a method of calculating the excitation amplitude value AMPIN and the phase difference correction amount PHMODIN in the excitation amplitude value / phase difference correction amount calculation circuit 30,
(1) The excitation amplitude value AMPIN and the phase difference correction amount PHMODIN are both calculated using a calculation variable from the outside.
(2) The phase difference correction amount PHMODIN is calculated from an external calculation variable, and the excitation amplitude value AMPIN is calculated from the phase difference correction amount PHMODIN or from the phase difference correction amount PHMODIN and an external calculation variable.
(3) The excitation amplitude value AMPIN is calculated from an external calculation variable, and the phase difference correction amount PHMODIN is calculated from the excitation amplitude value AMPIN or from the excitation amplitude value AMPIN and an external calculation variable.
Etc.

  In the excitation amplitude value / phase difference correction amount calculation circuit 30, any one or more of the rotation speed, load, and rotation direction of the stepping motor 11 is used as a calculation variable, and the calculation circuit counteracts the coil current of the stepping motor 11 and the back electromotive force. The excitation amplitude value AMPIN and the phase difference correction amount PHMODIN for reducing the fluctuation amount of the rotational torque determined by the electric power can be calculated.

  In the present embodiment, the stepping motor driving apparatus having the excitation amplitude value / phase difference correction amount calculation circuit 30 for calculating the excitation amplitude value AMPIN and the phase difference correction amount PHMODIN has been described. Instead of the correction amount calculation circuit 30, the excitation amplitude value and the phase difference correction amount associated with each other based on the calculation formula shown in (Expression 2) are stored as a table, and each excitation amplitude value AMPIN output from the table is stored. It is also possible to adopt a configuration in which the phases are driven and the excitation phase difference between the phases is corrected by the phase difference correction amount PHMODIN output from the table.

  As a calculation method of the excitation amplitude value AMPIN and the phase difference correction amount PHMODIN for reducing the fluctuation amount of the rotational torque of the stepping motor 11, the first coil and the second coil of the stepping motor 11 are calculated based on the calculation formula shown in (Formula 2). The excitation amplitude value AMPIN and the phase difference correction amount PHMODIN are calculated so that the excitation amplitude value of one coil is larger than the excitation amplitude value of the other coil, and the phase difference between the excitation signals is a predetermined value. The phase difference correction amount PHMODIN is calculated so as to be smaller than the phase difference, or is calculated so that the excitation amplitude value of one coil is smaller than the excitation amplitude value of the other coil, and the monk phase difference of the excitation signal is predetermined. There is a method of calculating the phase difference correction amount PHMODIN so as to be larger than the above phase difference.

With the above configuration, as in the case of the first embodiment, the fluctuation amount of the rotational torque can be reduced, and the driving sound of the stepping motor 11 can be reduced.
In the first to fourth embodiments, the excitation amplitude value AMPIN and the phase difference correction amount PHMODIN are configured as variables of the rotation speed, and the stepping motor drive circuit 1 is provided with an acceleration / deceleration function that changes the rotation speed. In the case of a circuit, in the acceleration / deceleration period, the excitation amplitude value AMPIN of each phase and the phase difference correction amount PHMODIN between the phases may be fixed values.

  Further, during the acceleration / deceleration period, each phase may be driven with the same excitation amplitude value AMPIN, and the phase difference correction amount PHMODIN between the phases may be set to zero.

  The stepping motor driving device of the present invention can suppress vibration of the stepping motor due to fluctuations in rotational torque and achieve further low noise with a simple device configuration. This is useful for reducing noise in electronic devices such as video cameras.

Explanatory drawing of the example of a measurement of the rotational torque at the time of driving a stepping motor in the conventional stepping motor drive device by the sine wave with the same amplitude which mutually shifted phase 90 degree Explanatory drawing of the example of calculation of the rotation torque fluctuation at the time of applying phase difference correction when the winding resistance of each phase of a stepping motor differs in the conventional stepping motor drive device The block diagram which shows the structure of the stepping motor drive device of Embodiment 1 of this invention. The block diagram which shows the structure of the excitation amplitude value / phase difference correction circuit in the stepping motor drive device of Embodiment 1 The block diagram which shows another structure of the excitation amplitude value / phase difference correction circuit in the stepping motor drive device of Embodiment 1 Conceptual diagram of phase correction and amplitude correction of the excitation signal of the stepping motor in the stepping motor driving apparatus of the first embodiment Explanatory drawing of the example of calculation of the rotational torque fluctuation at the time of applying a phase correction when the phase of each phase of a stepping motor in the stepping motor drive device of Embodiment 1 has shifted in the direction which spreads from 90 degrees When the phase of each phase of the stepping motor in the stepping motor driving apparatus according to the first embodiment is shifted from 90 degrees in a widening direction, the fluctuation of the rotational torque when the amplitude correction is applied after the optimum phase correction is applied. Illustration of calculation example Explanatory drawing of the measurement example of the driving sound of the stepping motor to which the phase / amplitude correction is applied in the stepping motor driving apparatus of the first embodiment The block diagram which shows the structure of the stepping motor drive device of Embodiment 2 of this invention. The block diagram which shows the structure of the stepping motor drive device of Embodiment 3 of this invention. The block diagram which shows the structure of the stepping motor drive device of Embodiment 4 of this invention. Block diagram showing the configuration of a conventional stepping motor drive device

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Stepping motor drive device 2 Clock signal generator 3 Up / down signal generator 4 Counter 5a, 5b, 6 ROM
7, 8 D / A converter 9, 10 Comparator 11 Stepping motor 12 Pattern signal generation circuit 13 Driver circuit 21 ROM
DESCRIPTION OF SYMBOLS 22 Excitation amplitude value / phase difference correction circuit 23 Excitation amplitude value input means 24 Phase difference correction amount input means 25, 26 Multiplier 27 Phase adjustment circuit 28 Phase difference correction amount calculation circuit 29 Excitation amplitude value calculation circuit 30 Excitation amplitude value / position Phase difference correction amount calculation circuit

Claims (18)

A stepping motor having a first coil and a second coil arranged with a predetermined phase difference;
Excitation amplitude value input means for inputting an excitation amplitude value for correcting the voltage or current value of each phase of the first coil and the second coil;
Phase difference correction amount input means for inputting a phase difference correction amount for correcting a phase difference of voltage or current between the phases of the first coil and the second coil;
For the stepping motor, each phase is driven by the excitation amplitude value from the excitation amplitude value input means, and the excitation phase difference between the phases is determined by the phase difference correction amount from the phase difference correction amount input means. A stepping motor driving device characterized by correcting. At least one input value of the excitation amplitude value and the phase difference correction amount is changed according to any one or more condition changes among the rotation speed, load, and rotation direction of the stepping motor. The stepping motor driving device according to claim 1. 3. The stepping according to claim 1, wherein the excitation amplitude value and the phase difference correction amount that reduce a fluctuation amount of a rotational torque determined by a coil current and a counter electromotive force of the stepping motor are input. Motor drive device. A stepping motor having a first coil and a second coil arranged with a predetermined phase difference;
Excitation amplitude value input means for inputting an excitation amplitude value for correcting the voltage or current value of each phase of the first coil and the second coil;
An arithmetic circuit for calculating a phase difference correction amount for correcting the phase difference of the voltage or current between the phases of the first coil and the second coil based on the excitation amplitude value from the excitation amplitude value input means. And
For the stepping motor, each phase is driven with an excitation amplitude value from the excitation amplitude value input means, and the excitation phase difference between the phases is corrected with a phase difference correction amount from the arithmetic circuit. A stepping motor driving device. The calculation circuit uses any one or more of the rotation speed, load, and rotation direction of the stepping motor as a calculation variable, and reduces the amount of fluctuation of the rotational torque determined by the coil current and back electromotive force of the stepping motor. The stepping motor driving device according to claim 4, wherein the phase difference correction amount to be calculated is calculated. 6. The stepping according to claim 4, wherein an input value of the excitation amplitude value is changed according to any one or more condition fluctuations among a rotation speed, a load, and a rotation direction of the stepping motor. Motor drive device. The stepping motor drive apparatus according to any one of claims 4 to 6, wherein the excitation amplitude value for reducing a fluctuation amount of a rotational torque determined by a coil current and a counter electromotive force of the stepping motor is input. . Instead of the arithmetic circuit, it has a table that stores the phase difference correction amount associated with the excitation amplitude value from the excitation amplitude value input means,
For the stepping motor, each phase is driven by the excitation amplitude value from the excitation amplitude value input means, and the phase difference output from the table according to the excitation amplitude value from the excitation amplitude value input means The stepping motor driving apparatus according to claim 4, wherein an excitation phase difference between each phase is corrected by a correction amount. A stepping motor having a first coil and a second coil arranged with a predetermined phase difference;
A phase difference correction amount input means for inputting a phase difference correction amount for correcting a phase difference of voltage or current between the phases of the first coil and the second coil;
An operation for calculating an excitation amplitude value for correcting the voltage or current value for each phase of the first coil and the second coil based on the phase difference correction amount from the phase difference correction amount input means. Circuit and
For the stepping motor, each phase is driven by the excitation amplitude value from the arithmetic circuit, and the excitation phase difference between the phases is corrected by the phase difference correction amount from the phase difference correction amount input means. Stepping motor drive device characterized by this. The calculation circuit uses any one or more of the rotation speed, load, and rotation direction of the stepping motor as a calculation variable, and reduces the amount of fluctuation of the rotational torque determined by the coil current and back electromotive force of the stepping motor. The stepping motor driving apparatus according to claim 9, wherein the excitation amplitude value to be calculated is calculated. The input value of the phase difference correction amount is changed according to any one or more condition fluctuations among a rotation speed, a load, and a rotation direction of the stepping motor. Stepping motor drive device. The stepping motor drive according to any one of claims 9 to 11, wherein the phase difference correction amount for reducing a fluctuation amount of rotational torque determined by a coil current and a counter electromotive force of the stepping motor is input. apparatus. Instead of the arithmetic circuit, it has a table storing the excitation amplitude value associated with the phase difference correction amount from the phase difference correction amount input means,
For the stepping motor, the excitation phase difference between the phases is corrected by the phase difference correction amount from the phase difference correction amount input means, and according to the phase difference correction amount from the phase difference correction amount input means. The stepping motor drive device according to any one of claims 9 to 12, wherein each phase is driven by an excitation amplitude value output from the table. A stepping motor having a first coil and a second coil arranged with a predetermined phase difference;
In order to correct the voltage or current value for each phase of the first coil and the second coil, using any one or more of the rotation speed, load, and rotation direction of the stepping motor as a calculation variable. And an arithmetic circuit for calculating a phase difference correction amount for correcting a phase difference of voltage or current between the phases of the first coil and the second coil,
For the stepping motor, each phase is driven with an excitation amplitude value from the arithmetic circuit, and an excitation phase difference between the phases is corrected with a phase difference correction amount from the arithmetic circuit. Stepping motor drive device. 15. The calculation circuit according to claim 14, wherein the calculation circuit calculates the excitation amplitude value and the phase difference correction amount that reduce a fluctuation amount of a rotational torque determined by a coil current and a counter electromotive force of the stepping motor. Stepping motor drive device. In place of the arithmetic circuit, it has a table that stores the associated excitation amplitude value and the phase difference correction amount,
For the stepping motor, each phase is driven with an excitation amplitude value output from the table, and an excitation phase difference between the phases is corrected with a phase difference correction amount output from the table. The stepping motor driving device according to claim 14 or 15. An acceleration / deceleration function for changing the rotation speed of the stepping motor is provided.
The stepping motor drive device according to any one of claims 1 to 16, wherein, in the acceleration / deceleration period, the excitation amplitude value of each phase and the phase difference correction amount between the phases are fixed values. An acceleration / deceleration function for changing the rotation speed of the stepping motor is provided.
18. The stepping motor drive device according to claim 17, wherein in the acceleration / deceleration period, each phase is driven with the same excitation amplitude value, and the phase difference correction amount between the phases is set to zero.

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