JP2000188898A - Driving device for stepping motor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To solve unstable operation, when a frequency detection means executes stepping driving and brushless drive, to stably operate respective drives and to precisely switch driving in the drive device of a stepping motor used in OA and an information unit. SOLUTION: A signal processing circuit 8 is installed and a signal for executing drive without brush is outputted from a drive circuit 2 from the signals of a position detection means 6 and a frequency detection means 7. At the switching of stepping drive, rotor information is outputted to a microstep circuit and therefore the drive device of a stepping motor, which is driven with a stable conduction signal and can precisely switch drive, is obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a driving device for a stepping motor.

[0002]

2. Description of the Related Art Conventionally, as a driving device for a stepping motor, one described in Japanese Patent Application Laid-Open No. 1-218398 is known. FIG. 6 shows a block diagram of a conventional driving device for a stepping motor. 6, reference numeral 1 denotes a stepping motor, 2 denotes a driving circuit for driving the stepping motor, 7 denotes frequency detecting means for detecting the rotation cycle of the stepping motor, and 101 denotes a signal for step-driving the stepping motor 1 according to a command pulse signal f. A counter processing circuit for counting the periodic signal of the frequency detecting means 7 and outputting a signal for brushlessly driving the stepping motor 1; and 9, comparing the periodic signal of the frequency detecting means 7 with the cycle of the reference signal. And a control circuit 10 for outputting a torque command signal i for rotating the stepping motor 1 at a predetermined cycle. When the switching signal h selects micro-step driving, the control circuit 10 outputs the signal and torque of the signal generation circuit 101 to the stepping motor. A target torque signal g to be generated is output to the drive circuit, and the switching signal h If you choose Siles driving a switching circuit for outputting a torque command signal i of the signal of the counter processing circuit 102 and the control circuit 9 to the driving circuit.

In the above configuration, the counter processing circuit 10
Reference numeral 2 denotes a switching signal h by calculating the rotor position of the stepping motor 1 by counting the period signal of the frequency detecting means 7 and generating a signal obtained by advancing the energizing signal phase at the time of driving the stepping motor by 90 degrees for brushless driving.
, The stepping motor can be rotated by switching between step driving and brushless driving.

[0004]

However, in the above-mentioned conventional configuration, since the rotor position of the stepping motor is calculated by counting the signal of the frequency detecting means, the erroneous counting of the counter due to noise of the frequency signal or the like occurs. Power cannot be supplied for brushless driving at an appropriate position, and operation becomes unstable. In addition, there is a problem in that if an erroneous count is made, it will not return to the original state unless it is corrected by driving the stepping motor.

SUMMARY OF THE INVENTION The present invention solves such a conventional problem. A stepping motor capable of accurately switching between brushless driving and microstep driving without causing unstable operation due to erroneous counting of a counter during brushless driving. It is an object to provide a driving device.

[0006]

SUMMARY OF THE INVENTION In order to solve the above-mentioned problems, the present invention provides a configuration in which a stepping motor is driven by switching between microstep driving and brushless driving using a signal from a rotor position detecting means and a signal from a frequency detecting means. It is what it was.

This makes it possible to correct an erroneous count of the counter during brushless driving, to eliminate unstable operation when the stepping motor is driven brushless, and to accurately switch between brushless driving and microstep driving.

[0008]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention according to claim 1 of the present invention provides a stepping motor, a driving circuit for driving the stepping motor, a micro step counter circuit for counting a command signal and outputting a count value, and A ROM circuit for outputting sine wave data corresponding to the counter value of the micro step counter circuit, a D / A converter for converting the data of the ROM circuit into a voltage value, and a position detecting means for detecting a rotor position of the stepping motor. A frequency detecting means for detecting a rotation cycle of the stepping motor, a signal for brushless driving the stepping motor based on signals from the position detecting means and the frequency detecting means, and a switching signal changed from brushless driving to stepping driving. Read edge signal and stepping motor A signal processing circuit that outputs a value corresponding to the rotor position to the micro step counter, a control circuit that compares a cycle of the signal of the frequency detection unit with a cycle of the reference signal, and outputs a torque command signal for rotating at a predetermined cycle, When the switching signal selects micro-step driving, the signal of the D / A converter and the target torque signal are output to the driving circuit. When the switching signal selects brushless driving, the signal of the signal processing circuit and the torque of the control circuit are output. This is a stepping motor drive device that has a switching circuit that outputs a command signal to the drive circuit.It eliminates unstable operation of the stepping motor due to erroneous counting of the counter during brushless driving, and also accurately performs brushless driving and microstep driving. At low speeds, micro-step drive improves position accuracy, Can be reduced has eliminated vibrates loss of synchronism of the stepping motor by the control of a brushless drive.

According to a second aspect of the present invention, there is provided a frequency detecting circuit for distributing a command pulse signal for driving the stepping motor to a control circuit and the micro step counter circuit according to a frequency and outputting a switching signal. 1. The driving device for a stepping motor according to item 1, wherein control of microstep driving and brushless driving can be switched by one command pulse signal, so that the number of terminals of the interface can be reduced. Can be handled.

[0010]

Embodiments of the present invention will be described below with reference to the drawings.

(Embodiment 1) FIG. 1 is a block diagram showing a stepping motor driving apparatus according to an embodiment of the present invention. 1, a stepping motor 1, a driving circuit 2 for driving the stepping motor 1, a microstep counter circuit 3 for counting a command pulse signal f and outputting a count value, and a microstep counter circuit 3
ROM that outputs sine wave data corresponding to the counter value of
Circuit 4, a D / A converter 5 for converting data of the ROM circuit 4 into a voltage value and outputting a drive A voltage signal d and a drive B voltage signal e, and a position A signal b by detecting the rotor position of the stepping motor 1. A position detecting means 6 for outputting a signal, a frequency detecting means 7 for detecting a rotation period of the stepping motor 1 and outputting a period signal a, and a position A for brushlessly driving the stepping motor 1 based on the position signal a and the period A signal b.
A signal processing circuit 8 that outputs a read signal j0 and a counter value j to the microstep counter circuit 3 by switching between the signal b, the position B signal c, and the switching signal h, compares the period of the periodic signal a with the period of the reference signal, and A control circuit 9 for outputting a torque command signal i for rotating in a cycle, and a D / A converter 5 when the switching signal h selects microstep driving.
The driving A voltage signal d, the driving B voltage signal e, and the target torque signal g are output to the driving circuit 2, and when the switching signal h selects the brushless driving, the position A signal b and the position B signal c of the signal processing circuit 8 are output. The torque command signal i of the control circuit 9 is applied to the drive circuit 2
And a switching circuit 10 for outputting the data to

In the above configuration, when the switching signal h selects the micro step driving, the micro step counter circuit 3 counts the command pulse signal f. The ROM circuit 4 outputs data corresponding to the value of the micro step counter circuit 3 to the D / A converter 5. The D / A converter 5 converts the data into a drive A voltage signal d and a drive B voltage signal e.
And outputs it to the switching circuit 10. The switching circuit 10 includes a drive A voltage signal d, a drive B voltage signal e, and a target torque signal g.
Is output to the drive circuit 2, and the stepping motor 1 rotates by micro-step drive according to the output of the drive circuit 2.
Next, when the switching signal selects the brushless drive, the signal processing circuit 8 counts the periodic signal a of the frequency detecting means 7 from the falling edge of the position signal b of the position detecting means 6 and calculates the position A signal b. A position B signal c and a position A signal b which are advanced by 90 degrees in phase are output. The control circuit 9 generates a periodic signal a
And a reference cycle, and outputs a torque command signal i from the difference. The switching circuit 10 outputs the position A signal b, the position B signal c, and the torque command signal i to the drive circuit 2, and the stepping motor 1 rotates by brushless drive by the energization signal of the drive circuit 2. In order to accurately switch from the brushless drive to the microstep drive, the signal processing circuit 8 outputs a counter value j and a read signal j0 corresponding to the rotor position of the stepping motor 1 to the microstep counter circuit 3 when the switch signal h switches. When the read signal j0 is input, the microstep counter circuit 3 reads the counter value j, and can accurately switch the drive by counting from the counter value j. An example of the configuration of the signal processing circuit 8 will be described with reference to FIGS.

FIG. 2 is a block diagram showing a signal processing circuit according to one embodiment of the present invention. FIG. 3 is a signal diagram for explaining the operation of the stepping motor driving device according to the embodiment of the present invention. In FIG. 2, the period signal a is reset at the edge of the position A signal b, and the counter value j is counted.
, A comparison circuit 82 that compares the count value j with a predetermined value and outputs a position signal c, and detects an edge of switching from brushless driving to micro-step driving of the switching signal h to detect an edge signal. It comprises an edge detection circuit 83 that outputs j0.

In the above configuration, the counter circuit 81 has four
The bit is reset when the position signal b rises or falls, and the periodic signal a is counted. The count value j is compared by the count 4 and the count 12 by the comparison circuit 82, and the position B signal c is output. The edge detection circuit 83 detects an edge at which the switching signal h switches from brushless driving to microstepping, and outputs a read signal j0. The data of the ROM circuit 4 corresponding to the counter value of the micro step counter circuit 3 becomes the drive A voltage signal d and the drive B voltage signal e.

With this configuration, there is no unstable operation due to erroneous counting of the counter during the brushless driving, and the brushless driving and the microstep driving can be accurately switched. The position accuracy is improved by the microstep driving at a low speed and the brushless at a high speed. By controlling the drive, the step-out of the stepping motor can be eliminated and the vibration can be reduced.

(Embodiment 2) FIG. 4 is a block diagram showing a driving device for a stepping motor according to an embodiment of the present invention. In FIG. 4, a stepping motor 1, a driving circuit 2 for driving the stepping motor 1, and a frequency detection for outputting a command pulse A signal f0, a command pulse B signal f1, and a switching A signal h0 according to the frequency of the command pulse signal f. A circuit 20, a microstep counter circuit 3 that counts the command pulse A signal f0 and outputs a count value, a ROM circuit 4 that outputs sine wave data corresponding to the counter value of the microstep counter circuit 3, and a ROM circuit 4 A D / A converter 5 for converting data into a voltage value and outputting a drive A voltage signal d and a drive B voltage signal e; a position detection means 6 for detecting a rotor position of the stepping motor 1 and outputting a position A signal b; Frequency detecting means 7 for detecting a rotation cycle of the stepping motor 1 and outputting a cycle signal a; A signal processing circuit 8 for outputting a read signal j0 and a counter value j to the microstep counter circuit 3 by switching between a position A signal b, a position B signal c, and a switching A signal h0 for brushless driving of the stepping motor 1; When the cycle of the signal a and the command pulse A signal f0 are compared and the control circuit 9 outputs a torque command signal i for rotating at the cycle of the command pulse A signal f0, and when the switching A signal h0 selects the micro step drive, D / A
The drive A voltage signal d, the drive B voltage signal e, and the target torque signal g of the converter 5 are output to the drive circuit 2, and when the switching signal selects the brushless drive, the position A signal b and the position B signal c of the signal processing circuit 8 And a switching circuit 10 for outputting a torque command signal i of the control circuit 9 to the drive circuit 2.

In the above configuration, when the cycle of the command pulse signal f is fast, the frequency detection circuit 20 outputs the command pulse B signal f
1 and the switching A signal h0 are output as a brushless driving command, and when it is late, the command pulse A signal f0 and the switching A signal h0 are output as a micro step driving command. Switching signal h
When 0 selects the micro step drive, the micro step counter circuit 3 counts the command pulse A signal f0. The ROM circuit 4 outputs data corresponding to the value of the micro step counter circuit 3 to the D / A converter 5. The D / A converter 5 converts the data into a drive A voltage signal d and a drive B voltage signal e, and outputs the data to the switching circuit 10.
The switching circuit 10 outputs the drive A voltage signal d, the drive B voltage signal e, and the target torque signal g to the drive circuit 2, and the stepping motor 1 rotates by microstep driving according to the output of the drive circuit 2. Next, when the switching A signal h0 selects brushless driving, the signal processing circuit 8 changes the position signal b of the position detecting means 6 from the falling edge of the frequency detecting means 7 to the frequency detecting means 7.
And outputs a position signal c and a position signal b, which are advanced by 90 degrees with respect to the position signal b. The control circuit 9 compares the periodic signal a with the command pulse signal f1, and outputs a torque command signal i based on the difference between the two. The switching circuit 10 outputs the position A signal b, the position B signal c, and the torque command signal i to the drive circuit 2, and the stepping motor 1 rotates by brushless drive by the energization signal of the drive circuit 2. In order to accurately switch from the brushless drive to the micro-step drive, the signal processing circuit 8 outputs a counter value j corresponding to the rotor position of the stepping motor 1 and a read signal j0 to the micro-step counter circuit 3 when the switch A signal h0 switches. . When the read signal j0 is input, the microstep counter circuit 3 reads the counter value j, and can accurately switch the drive by counting from the counter value j. A configuration example of the frequency detection circuit 20 will be described with reference to FIG.

FIG. 5 is a block diagram showing the frequency detection circuit 20 according to one embodiment of the present invention. 5, a low-pass filter circuit 21 for selecting a low frequency of the command pulse signal f, a high-pass filter circuit 22 for selecting a high frequency of the command pulse signal f, and a low-pass filter circuit 21
A buffer circuit A23 that adjusts the signal waveform of the signal pulse A and outputs a command pulse A signal f0, a buffer circuit B24 that adjusts the signal waveform of the high-pass filter circuit 22 and outputs a command pulse B signal f1, and a command pulse set by the command pulse A signal f0 It comprises an SR latch circuit 25 which is reset by the B signal f1 and outputs the switching A signal h0.

In the above configuration, the command pulse signal f is selected by the low-pass filter circuit 21 and the high-pass filter circuit 22 depending on the frequency. The buffer circuit A23 adjusts the signal waveform of the low-pass filter circuit 21 and the buffer circuit B24 adjusts the signal waveform of the high-pass filter circuit 22, and outputs the command pulse A signal f0 and the command pulse B signal f1, respectively. The SR latch circuit 25 is set by the command pulse A signal f0 and outputs the micro step drive command by the switching A signal h0, and is reset by the command pulse B signal f1 to output the brushless driving command to the switching A signal h0.

With this configuration, there is no unstable operation due to erroneous counting of the counter during the brushless driving, and the brushless driving and the microstep driving can be accurately switched. The position accuracy is improved by the microstep driving at a low speed and the brushless driving at a high speed. By controlling the drive, the step-out of the stepping motor can be eliminated and the vibration can be reduced. In addition, since control of microstep driving and brushless driving can be switched by one command pulse signal, the number of terminals of the interface can be reduced, and the brushless driving of the stepping motor can be handled like a stepping motor.

In the above description, an example has been described in which a two-phase stepping motor is used. However, a stepping motor having another number of phases can be similarly realized. Also, when the number of bits of the counter circuit 81 and the number of bits of the micro-step counter are not the same, the counter circuit 8
The same effect can be obtained by shifting the counter value of 1.

[0022]

As is clear from the description of the above embodiment,
According to the first aspect of the present invention, it is possible to accurately switch between the brushless driving and the micro-step driving without the unstable operation due to the erroneous counting of the counter during the brushless driving. Since the control of the micro step drive and the brushless drive can be switched by the command pulse signal, the number of terminals of the interface can be reduced, and the effect that the brushless drive of the stepping motor can be handled like a stepping motor can be obtained.

[Brief description of the drawings]

FIG. 1 is a block diagram illustrating a driving device for a stepping motor according to a first embodiment of the present invention.

FIG. 2 is a block diagram illustrating a signal processing circuit according to the first embodiment of the present invention.

FIG. 3 is a signal diagram for explaining an operation of the driving device of the stepping motor according to the first embodiment of the present invention.

FIG. 4 is a block diagram illustrating a driving device for a stepping motor according to a second embodiment of the present invention.

FIG. 5 is a block diagram illustrating a frequency detection circuit according to a second embodiment of the present invention.

FIG. 6 is a block diagram showing a driving device for a stepping motor in a conventional example.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 stepping motor 2 drive circuit 3 micro step counter circuit 4 ROM circuit 5 D / A converter 6 position detection means 7 frequency detection means 8 signal processing circuit 9 control circuit 10 switching circuit 20 frequency detection circuit 21 low-pass filter circuit 22 high-pass filter circuit 23 Buffer circuit A 24 Buffer circuit B 25 SR latch circuit 81 Counter circuit 82 Comparison circuit 83 Edge detection circuit 101 Signal generation circuit 102 Counter processing circuit a Period signal b Position A signal c Position B signal d Drive A voltage signal e Drive B voltage signal f Command pulse signal f0 Command pulse A signal f1 Command pulse B signal g Target torque signal h Switching signal h0 Switching A signal i Torque command signal j Counter value j0 Read signal

Claims (2)

[Claims] A stepping motor; a driving circuit for driving the stepping motor; a microstep counter circuit for counting a command signal and outputting a count value; and a sine wave data corresponding to a counter value of the microstep counter circuit. A ROM circuit for outputting,
A D / A converter for converting data of the OM circuit into a voltage value; a position detecting means for detecting a rotor position of the stepping motor; a frequency detecting means for detecting a rotation cycle of the stepping motor; The signal from the frequency detecting means is used to detect a signal for brushless driving the stepping motor and an edge when the switching signal is changed from the brushless driving to the stepping drive, and read the read signal and a value corresponding to the rotor position of the stepping motor. A signal processing circuit for outputting to the step counter, a control circuit for comparing the cycle of the signal of the frequency detecting means with the cycle of the reference signal and outputting a torque command signal for rotating at a predetermined cycle, and a switching signal for selecting the micro step drive In this case, the signal of the D / A converter and the target torque signal are transmitted to the drive circuit. If signal Setsu to force selected the brushless drive driving device of a stepping motor and a switching circuit for outputting a torque command signal of the signal and the control circuit of the signal processing circuit to the drive circuit. 2. The stepping motor driving device according to claim 1, further comprising a frequency detection circuit that distributes the switching signal to a control circuit and a micro step counter circuit in accordance with the frequency of the command pulse signal for driving the stepping motor.