JPS61142996A - Stepping motor controller - Google Patents

Abstract

PURPOSE:To freely select a drive pulse rate in response to the desired driving characteristic even when a load varies by detecting a drive pulse rate and a drive current to control the drive current. CONSTITUTION:A voltage across a current detecting resistor 7 is input to a differential amplifier composed of an operational amplifier 15, amplified to the prescribed level, and led to - input terminal of a comparator 13 through a signal line 12. On the other hand, drive pulses phi1, phi2 of terminals 1, 2 are led to the input terminals of exclusive OR gate 16, the output signal is input through a signal line 8 to an F/V converter 9, and the output is input to + input of the comparator 13. The output signal of the comparator 13 controls the input of 2-input NAND gate 14 through a current limiting resistor to control a phase drive current constantly.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field] The present invention relates to a stepping motor control device, and more particularly to a stepping motor control device that improves the driving characteristics of a stepping motor.

[Prior Art] With the development of various microcomputer-applied devices in recent years, stepping motors have been widely used as operating members that are compatible with digital control, easy to control, and have a wide range of use. Further, various phase excitation methods and methods for controlling the drive pulse rate are known in order to control the torque, speed control, or stop position accuracy of the stepping motor as desired. - However, in conventional stepping motor drive systems, the drive voltage and current are constant, so if an inappropriate drive pulse rate is given to give priority to the desired drive characteristics, there is a risk of out-of-step or synchronization phenomena. Ta. For example, if a low drive frequency is applied to a motor with low friction torque at startup, a rotational state accompanied by vibrations, a so-called disturbance phenomenon, will occur. Furthermore, it is well known that during continuous operation, when the load torque is increased, a tax adjustment phenomenon occurs at the end.

[Objective] The present invention has been made in view of the above problems, and an object of the present invention is to provide a stepping motor control device that can obtain stable rotational driving force using a wide range of pulse rates.

[Structure of the Invention] In order to achieve the above object, the present invention includes means for detecting the drive pulse rate of the stepping motor, means for detecting the drive current flowing through each phase of the stepping motor,
A configuration is adopted in which means is provided for controlling the phase drive current of the stepping motor in accordance with the output of the pulse rate detection means and the detection output of the drive current detection means.

[Example] Hereinafter, the present invention will be described in detail based on the example shown in the drawings. However, in the following, a case will be exemplified in which a four-phase stepping motor is driven in two phases.

FIG. 1 shows the configuration of an embodiment of a stepping motor control device according to the present invention, and terminals indicated by symbols 1 to 4 in the figure input drive pulses φl to φ4 of each phase of a four-phase stepping motor, respectively. . Here, only one phase of the stepping motor indicated by reference numeral 6 is illustrated, and the illustration of the other phases of the drive circuit is similarly omitted.

In FIG. 1, omitted parts are indicated by broken lines.

The drive pulse φl is connected to the two-man NAND 1 via the terminal l.
4, the logic is inverted and input to the base of a transistor 5 for phase current switching. The emitter of transistor 5 is connected to the power supply voltage +VOP, and the drive pulse φl
By controlling the base of transistor 5, phase 6 of the stepping motor connected in series with transistor 5 is excited.

The pattern of phase excitation is as shown in Fig. 2.
A so-called two-phase excitation force formula is adopted in which the two phases are sequentially placed in an excited state simultaneously by overlapping φ4. The pulse rate at this time is indicated by the period of one phase, so the second
In the case of the figure, if the pulse rate is N, the period of the drive pulse φl is 1/N.

The other end of each phase of the stepping motor on the opposite side of the driving transistor is connected to a current detection resistor 7, and the opposite side of the resistor 7 is connected to one side of the driving power supply voltage -VOP. Therefore, the sum of the currents flowing through each phase flows through the resistor 7. The voltage corresponding to the phase current distribution across the resistor 7 is input to a known differential amplifier composed of an operational amplifier 15, amplified to a predetermined level, and guided to one input terminal of a comparator 13 via a signal line 12. .

On the other hand, the drive pulses φl and φ2 of the terminals 1.2 are led to the input terminal of the exclusive OR gate 16, and the exclusive OR signal is sent to the F/V converter 9 via the signal line 8.
has been entered. The signal on this signal line 8 is shown at the bottom of FIG.

If the period of this signal is expressed by the drive pulse rate mentioned above, it is 1
It becomes 72N.

The F/V converter 9 is a known frequency-to-voltage conversion circuit that outputs a voltage according to the pulse frequency of the signal line 8, and the voltage signal according to the frequency of the exclusive OR signal of the drive pulses φl and φ2 is a signal. A voltage dividing resistor R for level matching is connected to the comparator 13 provided for each phase through the line lO.
1, R2 and the signal line 11. The comparator 13 is composed of an operational amplifier element and the like.

The comparator 13 compares the voltage value according to the frequency of the exclusive OR signal of the drive pulses φl and φ2 input from the signal line 11 with the voltage value according to the sum of the phase drive currents of the signal line 12, The drive current is controlled in accordance with the comparison output, that is, the output signal of the comparator 13 controls the input of the two-man NAND gate 14 via a current limiting resistor to control the phase drive current at a constant current.

Next, the operation of the above configuration will be explained in detail.

Now, if we consider the section indicated by the symbol A in Fig. 2,
Here, the driving pulses φ4 and φl become high level at the same time, which turns on the transistor 5, and at the same time, the phase corresponding to the driving pulse φ4 is also excited via a transistor (not shown).

As a result, the moving element of the stepping motor (not shown) is
A fixed amount is advanced, and the stepping motor is driven. During this time, the drive pulses φl and φ4 are applied to the current detection resistor 7.
The sum of the phase drive currents flows. This current value is controlled by the output of the comparator 13 shown in FIG.

That is, a reference voltage value corresponding to the time pulse of the signal line 8 formed by the exclusive OR signal of the drive pulses φl and φ2 is generated by the F/V converter 9, and the operational amplifier 15 The phases to be excited are driven with current values according to the pulse rate by comparing the phase current values output by and applying the comparison output to the base of the driving transistor of each phase. Specifically, as the pulse rate increases, the reference voltage value of the signal line 11 increases, thereby increasing the base current of the driving transistor and increasing the current flowing through each phase. Conversely, when the pulse rate becomes low, the level of the signal line it decreases, so the drive current of each phase is reduced.

As described above, the phase drive current is determined according to the desired drive pulse rate, so even if the load on the motor fluctuates, unlike the conventional drive system using a fixed current value, there will be no disturbance.
Stable rotational characteristics can be obtained without causing step-out phenomena.

Although drive control of a four-phase stepping motor has been described in the above embodiment, the technique of the present invention is not limited thereto, and can of course be applied to control of stepping motors having other numbers of phases. Furthermore, although the pulse rate is detected by taking the exclusive OR of two predetermined phase drive pulses, it is of course possible to directly detect the pulse rate of the predetermined phase drive pulse. be.

[Effects] As is clear from the above description, according to the present invention, means for detecting the driving pulse rate of a stepping motor;
A configuration is adopted that includes means for detecting the drive current flowing through each phase of the stepping motor, and means for controlling the phase drive current of the stepping motor in accordance with the output of the pulse radar detection means and the detection output of the drive current detection means. Therefore, it is possible to provide an excellent stepping motor control device that can freely select a drive pulse rate according to desired drive characteristics even when there are load fluctuations, and can obtain stable drive characteristics.

[Brief explanation of the drawing]

FIG. 1 is a circuit diagram showing the configuration of a stepping motor drive control circuit according to the present invention, and FIG. 2 is a timing chart explaining the operation of the circuit of FIG. 1-4...Terminal 5...Transistor 6...
・Phase 7, R1, R2...Resistance 9...
F/V converter 13... Comparator 15... Operational amplifier

Claims (1)

[Claims] means for detecting a driving pulse rate of the stepping motor; means for detecting a driving current flowing through each phase of the stepping motor; and a means for detecting a driving current flowing through each phase of the stepping motor; A stepping motor control device comprising means for controlling drive current.