JPS6139899A - Drive device for stepping motor - Google Patents

Abstract

PURPOSE:To perform a complicated microstep control only by a digital circuit by applying a pulse drive signal having different pulse width according to data stored in memory means to the prescribed coil. CONSTITUTION:An up-down counter 1 for counting an input clock signal input from a terminal 1a, a phase controller 2 for sequentially converting a step to be driven on the basis of the frequency dividing output of the input clock, and memory means 3, 4 for outputting different data according to the output of the counter are provided, and the pulse widths of flip-flops 8, 9 for driving stator coils are controlled in response to the counting of preset counters 5, 6 on the basis of data stored in ROMs 3, 4.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of the Invention] The present invention relates to a driving device for driving a stepping motor in two phases, and particularly to a driving device that performs microstep driving to minutely change the step angle.

[Prior art and its problems]

As one method of driving a stepping motor, a two-phase excitation method is known in which two stator coils are energized at the same time and the combination is sequentially changed to rotate a rotor. However, in a stevening motor, the step angle is determined by the motor itself, but in order to further subdivide the step angle, the current flowing through the pair of stator coils is changed stepwise within a certain range. A microstep drive is known in which the stopping position of the rotor is subdivided by sequentially changing the ratio of flowing current (for example, U.S. Pat. No. 3.4
45.741 No. 3,885,210 or JP-A-57-
No. 49394). In such a drive circuit, the power consumption in the drive transistor that drives the stator coil is large and the efficiency is low, so it is necessary to use a drive transistor with a large current capacity, and the drive circuit becomes expensive and is not suitable for large pulse motors. The drawback was that it could not be used. Furthermore, in order to achieve the same high-speed drive as in normal step drive during microstepping, it is necessary to increase the resistance value of the resistor connected in series with the stator coil, and these resistors consume a lot of power. This has the disadvantage of further deteriorating efficiency.

Furthermore, instead of changing the current stepwise, a driving method has been proposed in which the stator coil is driven in a pulsed manner and the average current is changed by changing the pulse width to perform microstep driving (Japanese Unexamined Patent Application Publication No. 1983-1999). No. 106399). However, according to this method, it is necessary to synchronize the cycle of the pulse generator for performing microstepping with the input clock cycle that advances the combination of energized stator coils, and it is necessary to synchronize the cycle of the pulse generator to perform microstepping with the input clock cycle that advances the cycle. However, there is a problem in that it is necessary to change the period of the pulse generator, and a complicated analog circuit is required.

Also, a technology has been proposed in which a microprocessor is used to PWM modulate the drive waveform of the stator coil (Japanese Patent Application Laid-Open No.
No. 8-79499), the stepping motor is rotated smoothly, but the stepping motor is not driven in microsteps, and in this case as well, there is a problem in that a D/A converter or the like is required.

[Purpose of the invention]

The present invention has been made in view of the problems of the conventional microstep drive of a stepping motor, and it is possible to easily change the operating state without using complicated analog circuits such as a D/A converter. An object of the present invention is to provide a stepping motor driving device that can perform the following steps.

[Structure and effects of the invention]

The present invention is a stepping motor driving device that performs two-phase excitation by energizing a pair of stator coils among a plurality of stator coils in different combinations, the device comprising a counting means for counting an input clock period, and a frequency-divided output of an input clock. a phase control means for sequentially switching the stator to be driven based on the input clock; a pulse generation means for generating a pulse signal having a constant period shorter than the input clock; and a storage means for outputting different data based on the counting output of the counting means. , a drive signal generation means that counts the output pulses of the pulse generation means and generates drive signals of different pulse widths based on data given from the storage means; and a drive signal of the drive signal generation means that is applied to the stator selected by the phase control means. The present invention is characterized by comprising a logical means for giving the following.

According to the present invention having such characteristics, a pulse drive signal having different pulse widths is applied to a predetermined stator coil according to data stored in the storage means without using a complicated analog circuit such as a D/A converter. can give. Therefore, it is possible to construct a microstep drive device having an arbitrary step angle set in advance.

Since complex microstep control is realized using only digital circuits, the drive circuit can be made smaller and less expensive, and it can also be easily integrated into an IC or CPU. It is possible to provide a motor drive.

[Explanation of Examples]

(Description of First Embodiment) FIG. 1 is a circuit diagram of a unipolar two-phase drive device for a stevening motor showing an embodiment of the present invention.

In the figure, an up/down counter 1 is a counter that counts clock signals applied from an input terminal 1a, and in this embodiment, a 4-bit binary counter is used. An input terminal 1b of the up/down counter 1 is supplied with a signal in a counting direction corresponding to the rotating direction of the stevening motor. For example, when the input terminal 1b is at "L" level, the counter 1 counts the amps and rotates the stepping motor in the forward direction, and when the input at the input terminal 1b is at "H", the counter 1 counts down and rotates the stepping motor in the reverse direction. shall be. The count value of amplifier down counter 1 is “
0'' and an intermediate value of 8, a pulse signal is transmitted from the output terminal IC to the phase control circuit 2. The phase control circuit 2 counts and rezo-codes this input pulse using, for example, a quaternary counter, and outputs a well-known two-phase excitation signal 2a1. 2a2. It occurs as 2bl, 2b2.

Now, the 4-bit count output of up/down counter 1 is 1do.
~ld3 are two read-only memories (hereinafter referred to as ROM) 3 and 4 have address designation signals “0” ~rFJ
(expressed in hexadecimal). ROM3 and 4 are 4 pin parallel signals 1do~ from up/down counter 1
According to the input of 1d3, data that changes as shown in FIG. 2 is stored. In other words, the address of ROM3 is "0"
From address "8" to "F" increases monotonically from "8" to "F".
data 3 ao to 3 am, which decreases between addresses ``0'' and ``8'', and data 4 that decreases monotonically between addresses ``0'' and ``8'' and increases between addresses ``8'' and rFJO.
From ao to 4am. The number of focuses of the output data of ROM3.4 is determined by the number of divisions between the maximum value and minimum value of the pulse width that drives the stator coil. For example, if a resolution of 32 is provided, 5-bit data (rrr=4) is determined. do. Output data 3ao to 3am+ of this ROM3.4
4ao to 4am are given to breset counters 5 and 6, respectively, as breset values. The preset counters 5 and 6 count a predetermined clock signal given from an oscillator 7 as shown in FIG. 1, and their counting capacity is R.
It is assumed that the number of bits is greater than or equal to the number of bits set by OM3 and OM4. And preset counters 5 and 6 are stored in ROM3.
The clock period of the oscillator 7 is determined so that the counting time for counting up to the maximum preset value given from 4 and 4 is a fraction of the shortest period of the high-power pulse given to the amplifier down counter There is.

It is sufficient that the period of the oscillator 7 satisfies this relationship, and the period of the oscillator 7
There is no need for a synchronization relationship between the clock and the large clock given to the amplifier down counter 1.

When the count values of the preset counters 5 and 6 reach 0, pulse outputs are output from the output terminals 5a and 6a, respectively, and are applied as set inputs to the RS Frisobfromps 8 and 9, respectively. Also, when the count value of the counter 5゜6 reaches the preset value, outputs are sent from the output terminals 5b and 6b respectively to R.
It is given as a reset input to the S flip-flops 8 and 9. The Q output of the flip-flop 8 is applied to one input terminal of the two AND circuits 10al and 10a2 via the output terminal 8a, and the Q output of the flip-flop 9 is applied to the two AND circuits 10bl via the output terminal 9a.

It is applied to one input terminal of 10b2. The brisset counters 5 and 6 and the flip-flops 8 and 9 are ROM
3.4 constitutes a drive signal generating means that provides outputs with different pulse widths based on the brisset data given from 3.4. AND circuit 10al.

10a2 receives the phase control signal 2al from the phase control circuit 2, respectively.
, 2a2 are given, and AND circuit 10b1.10
phase control signal 2b1.b2 from the phase control circuit 2. 2
b2 is given. AND circuits 10a1 to 10b2
provides AND signals of these inputs to driving L transistors 1181 to 11b2, respectively. Transistor 11a
1 to 11b2 open and close according to input signals to connect the four stator coils 12aL1 of the 4-phase stepping motor 12.
2a2. 12bl and 12b2 are driven to rotate the stepping motor 12.

(Operation of this embodiment) Next, the operation of this embodiment will be explained. Figures 3 and 4
The figure is a waveform diagram showing output waveforms of the amplifier down counter 1, the phase control circuit 2, and the drive signal generator. In Fig. 3, the input terminal 1b of the up/down counter 1 is first connected to “
It is assumed that the "L" level is set and the amplifier count is specified.

Assuming that the clock signal shown in FIG. 3 fbl is applied to the input terminal 1a, the pulse is divided into 1/8 and is controlled by the phase control circuit 2 from the output terminal 1c as shown in FIG. 3 fc). A clock signal is provided that advances the phase. Based on this clock signal, the phase control circuit 2 outputs well-known two-phase drive phase control signals 2aL 2 a2 .
Outputs 2 bl and 2 b2. On the other hand, due to the up-count of amplifier down counter 1, 4-bit parallel output is given as address data from terminals 1do to 1d3 to ROMs 3 and 4, and as shown in FIG. 2, different data is sent to preset counters 5 and 6 for each count value. Preset. The preset counters 5 and 6 continue counting independently based on the clock signal of the oscillator 7,
When the count output becomes 0, flip-flops 8 and 9 are set, and when the count output reaches the preset value, flip-flop 8 is set.
and 9 reset. The preset value is set to RO every time an input pulse is applied to the input terminal 1a of the amplifier down counter 1.
Since the output data of M3 and M4 are different, the timing at which the flip-flop 18.9 is reset changes as shown in FIG.

Therefore, output terminals 8a and 9 of flip-flops 8 and 9
The timing signal given to the AND circuits 10a1 to 10b2 from RO
It changes to a value corresponding to the data set as the output of M3.4.

Assuming that 2 al and 2 bl of the phase control outputs of the phase control circuit 2 are at the "H" level after the current side t1, the AND circuits 10a1. 10bl connects the output signals 8a and 9a of the flip-flops 8 and 9 to the transistor 1.
1aL and 11bl to drive the stator coils 12al and 12bl of the stepping motor 12.

Then, an average current proportional to the pulse width flows through the stator coils 12al and 12bl. The stators of the stator coils 12al and 12bl that are energized at that time generate magnetic flux due to the uniform current flowing there, and the rotor stops at a point where the attractive or repulsive forces of the two stator coils 12al and 12b1 are balanced. I will do it. When the next pulse is applied to the input terminal 1a of the amplifier down counter 1, the read address of the ROM 3.4 advances and the preset values given to the respective preset counters 5.6 change. Therefore flip-flop8.9
The output pulse width changes, the balance point changes, and the rotor moves to the next step. In this way, as shown in the average current waveform in Figure 3 (hl, (J)), each time a large force pulse is applied, the stepping motor 12
The rotor is driven by a microstep drive in which it rotates by a minute angle according to data preset in the ROM 3.4.

Then, at time t2 when the up-down counter 1 reaches the intermediate value or 0 point, the phase of the phase control circuit 2 changes as shown in FIG. That is, after time t2, a signal is added from the output terminal 1c of the up/down counter, so that the phase control signal 2a2.2 of the phase control circuit 2 is generated.
bl becomes "H" level, and AND circuits 10a2 .
Close the 10bl gate.

Therefore, transistor 11a2. 3rd via 11bl
As shown in the average current waveforms in Figures (1) and (j), the stator coils 12a2. 12bl is driven such that the drive current changes sequentially in accordance with the input clock of the input terminal 1a. In this way, the rotor sequentially rotates by sequential microstep driving between the two stators.

When the stepping motor 12 is reversed, an "H" level output is given to the input terminal 1b of the up/down counter 1, and the phase control signal 2al, 2 of the phase control circuit 2 is output.
Reverse the phases of a2, 2bl, and 2b2.

In this way, it is possible to perform microstep driving in the same manner.

As is clear from this operation explanation, the pulse width of the flip-flop 8.9 that drives each stator coil is obtained according to the counts of the preset counters 5 and 6, but the input terminal 1
The oscillator 7 does not need to be synchronized with the input clock to the amplifier down counter 1 applied to the amplifier down counter 1, and the preset counter 5.6 finishes counting faster than the input clock period applied to the terminal 1a of the amplifier down counter 1. It is sufficient to select the oscillation period of .

In this embodiment, the pulse widths applied to the two stator coils are changed simultaneously each time the incoming pulse is added to the amplifier down counter, but by fixing one pulse width and changing only the other, the pulse width between the stator coils is changed. It is also possible to change the balance point of the attraction or repulsion force to create a micro-stamp. These microstep angles can be arbitrarily changed by setting the ROM 3 or 4. Further, in this embodiment, each configuration is implemented by hardware, but it is also possible to configure the configuration so that equivalent functions are implemented by a microprocessor.

(Description of Second Embodiment) FIG. 5 is a circuit diagram showing a second embodiment of the stepping motor drive circuit according to the present invention. In this figure, the same parts as those in the embodiment of FIG. 1 are indicated using the same reference numerals. In this embodiment, the ROM 4, the preset counter 6, and the flip-flop 9 are omitted, and the Q output and d output of the flip-flop are used as the outputs of the flip-flop 8, and the AND circuit 10a1.
10a2 and 10b1. It is given to 10b2. The AND circuits 10a1 to 10b2 receive the phase control signals 2al, 2a of the phase control circuit 2, as in the embodiment described above.
2. 2 bL 2 b2 are grouped together and drive the stator coils 1281 to 12b2 of the stamping mask 12 via driving transistors 1181 to 11b2, as in the first embodiment.

According to this embodiment, since the flip-flop 8 is set during the time from when the preset counter 5 starts counting from "0" until it reaches the preset value, a Q output is obtained from the output terminal 8al, and the AND circuits 10al and 10a2 is given the output. Furthermore, since the flip-flop 8 is reset during the time from when the preset value is reached until it becomes O again, the output from 8a2 is given to the AND circuits 10bl and 10b2. Therefore, as in the waveform diagram shown in FIG. 4, two drive signals having different pulse widths are obtained corresponding to the set values. According to this embodiment, since the drive outputs of the flip-flops are symmetrical, it is not possible to set the pulse widths for driving the two stator coils independently of each other as in the first embodiment. However, since a stepping motor has nearly symmetrical characteristics with respect to each stator coil, even if a drive signal with a reversed phase is used as in the embodiment shown in FIG. 5, a practically sufficient microstep drive circuit can be configured with a simple configuration.

[Brief explanation of the drawing]

FIG. 1 is a circuit diagram showing an embodiment of the stamping moke drive device according to the present invention, FIG. 2 is a diagram showing output data for addresses stored in ROMs 3 and 4, and FIG. 3 is a waveform showing waveforms of each part. 4 is a waveform diagram showing drive signals for the input cabling and two flip-flops 8.9, and FIG. 5 is a circuit diagram showing another embodiment of the stepping motor drive device according to the present invention. 1------Amplifier down counter 2---------
One phase control circuit 3.4---ROM 5.6
−−−−Brise Soto Kaunk 7−−−−−Generator
8. 9---Flip-flop 10al,
10a2. 10bl, 10 b2---AND circuit 11al, 11a2. 11bl,
11b2-----1-ransistor 12----
Stepping motor 12a1. 12a2. 12
bl, ] ] 2b2 ------- Stator coil patent applicant Tateishi Electric Co., Ltd. agent Patent attorney Yoshiki Okamoto (1 person)
12a2.12b1.12b2 ------- Slurter file Figure 2 ROM 7 Dress Figure 4 Figure 3 Figure 5

Claims (3)

[Claims] (1) A stepping motor driving device that performs two-phase excitation by energizing a pair of stator coils among a plurality of stator coils in different combinations, the device comprising a counting means for counting input clock signals, and a frequency-divided output of the input clock. a phase control means for sequentially switching the stator to be driven based on the input clock; a pulse generation means for generating a pulse signal having a constant period shorter than the input clock; and a memory for outputting different data based on the counting output of the counting means. means, drive signal generation means for counting output pulses of the pulse generation means and generating drive signals of different pulse widths based on data provided from the storage means; and driving the stator selected by the phase control means. A stepping motor drive device comprising: logic means for providing a drive signal for the signal generation means. (2) The storage means is first and second storage means that respectively output different data based on an input clock, and the drive pulse generation means is a first and second storage means that outputs different data based on an input clock, and the drive pulse generation means is a first and second storage means that outputs the output of each storage means as a preset value, respectively. Stepping according to claim 1, characterized in that it has a second preset counter and a plurality of flip-flops that are set and reset when the count value of each preset counter reaches a preset value and a reset value. Motor drive device. (3) The storage means is a storage means that outputs different data based on an input clock, and the drive pulse generation means includes a preset counter whose output is a preset value, and whose count value is a preset value. and a flip-flop that is set and reset when a reset value is reached, and uses the two pulse outputs as respective stator coil drive signals.