JPS63117697A - Drive circuit for step motor - Google Patents

Abstract

PURPOSE:To continuously vary the rotating speed of a step motor by an analog input signal in a wide range by providing a pulse signal generator for converting an analog signal to a step motor drive pulse. CONSTITUTION:An absolute value amplifier 2 makes an analog input signal 1 show absolute value. A v/f converter 3 forms a pulse signal of a frequency proportional to the absolute value of the analog input signal. A comparator 4 judges the positive or negative of the signal 1. The output of the comparator 4 and the output of the converter 3 are input to a speed control pulse signal generator 5 to generate the drive pulse of a step motor.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a step motor drive circuit that controls the rotation speed and rotation direction of a step motor.

[Summary of the invention]

The present invention provides a speed control Noculus signal generation circuit in a step motor drive circuit, in which the rotational speed of the step motor is proportional to the magnitude of an analog signal input to the circuit, and the direction of rotation is determined by the positive or negative sign of the input analog signal. This is what I did.

Next, the absolute value of the input signal is first taken, and then a pulse signal with a frequency proportional to the absolute value of the input analog signal is created using a voltage-to-frequency conversion circuit (μ-lower Vf converter). Also, a comparator is used to determine whether the input signal is positive or negative. The purpose is to obtain a speed control pulse signal for controlling the rotational direction and speed of the step motor from this controller output and the pulse signal.

[Prior Art] In order to drive a step motor, a configuration as shown in FIG. 82 is required. The speed of the step motor is determined by the output of the pulse signal generator shown in FIG. 2, and this part is composed of a microcomputer, a dedicated controller IC, an oscillator, and a logic circuit, and there are various ways of constructing it. Conventionally, the control signal shown in FIG. 28 is a digital signal, and when controlling the speed of a step motor using an analog signal, it is necessary to incorporate an analog-to-digital converter (hereinafter referred to as an A/D converter) into the device. Ta.

[Problems to be Solved by the Invention] When the speed of a step motor is controlled using a conventional speed control pulse signal generator, the speed control signal from the outside is a digital signal, so the rotation speed variable range is narrow. Therefore, the rotational speed that can be obtained is limited. Further, due to the circuit configuration, the rotation speed may not be easily changed in some cases.

When applying a step motor, it may be more convenient to use an analog signal as an external speed control signal.

For example, when a step motor is applied to a simple positioning servo, an error signal indicating the difference between a target position and a current position is detected as an analog signal, and this is used as a speed control signal. However, the conventional speed control pulse signal generator requires an A/D converter and the like, resulting in a complicated and expensive configuration.

The present invention uses an analog signal as an input signal so that the rotation speed of the step motor can be continuously changed over a wide range, and the rotation speed and rotation direction can be determined by the magnitude and sign of the analog signal. The purpose is to construct a circuit that has a control function.

[Means for Solving the Problems] In the step motor drive circuit of the present invention, (a) a step motor sounding circuit having a pulse signal generating circuit for controlling the rotation speed and a circuit for driving the step motor, (b) ) The speed control pulse signal generation circuit has an analog signal input section, and an absolute value amplification circuit (c) that outputs the magnitude of this analog input signal (d) A circuit that determines whether the input signal is positive or negative (d) Absolute value of the analog signal An electric/pressure frequency conversion circuit (θ) that outputs a pulse signal with a frequency proportional to the value. Speed control that controls the rotational speed and direction of the step motor using the pulse signal and the output from the circuit that determines whether the input signal is positive or negative. Does it have a circuit that can obtain pulse signals? Features.

[Examples] Hereinafter, the present invention will be described in detail based on Examples.

FIG. 1 is a block diagram of a step motor drive circuit of the present invention. 1 is the input analog signal.

2 is an absolute value amplifier. An example of this circuit is shown in FIG.

In this circuit, there are two offset volumes) % phasing volume 31.
32 is attached, and Eli is concerned about adjusting this optimally.
Accurate input signal absolute value conversion can be performed. Also, depending on the size of the input signal and the size of the required output signal, the input side and the output 111! The gain of the + non-inverting amplifier can be determined. 3 is a Vf converter. This circuit inputs the output from the absolute value amplifier to generate a pulse signal of the next station wave number which is proportional to the absolute value of the analog input signal.

Several voltage-frequency conversion methods have been devised, and some are easily realized. Here, FIG. 4 is shown as an example.

In this circuit, the input Vin to the 12 input comparators
The operation differs depending on the magnitude relationship of , VB. Vin
) VB, the comparator turns on and at the same time a single pulse is output from the one shot. While this single pulse is on, the output of the U, V-f converter VOut
is turned off, and at the same time, the υ1 flow source operates. Then, the current from the current source charges the capacitor CB, vB rises, and when the single foil pulse is on, vln < VB. At the same time as the output from the one shot turns off, the output Vout turns on and the current #Vi stops operating. Then, discharge begins via the charge \iRB stored in cB, and cooling continues until Vi '' VB.

Then, the same operation as above is repeated again.

The frequency of this output pulse signal is equal to the input signal Vin
is determined according to the size of

If necessary, an integrator using an operational amplifier may be used in the RB-CB parallel circuit shown in FIG.

Numeral 4 is a converter for determining whether the input signal is positive or negative.By setting the converter level to ov, the positive or negative can be determined.

The output of the comparator and the output of the vf converter are
An example of this circuit, which is input to the speed control pulse signal generator of the present invention, is shown in FIG. This circuit drives a step motor using a "two-phase excitation method."

In the two-phase excitation method, the periods are equal and the duty is 1.
The speed is controlled by excitation according to the two pulses 1 and 2, and the magnetic field within the motor is turned on and off over time.

One pulse has a phase difference of 90° from another pulse (referred to as a reference pulse under μ), and the direction of rotation is determined by whether the phase is advanced or delayed by 90′ with respect to the reference pulse. In the circuit of FIG. 5, the frequency of the output pulse from the Vf converter is divided using a 14 frequency divider. By appropriately setting the frequency division ratio of the frequency divider, the variable range of the rotation speed can be set. In Figure 5, (7) is the reference pulse output, and (A) is the reference pulse with a phase of 90°.
The pulse output is shifted by °. Q) is the output from the comparator, and if this output is on, the signal Q is output, and if it is off, the signal Q is output. This time chart number 6
As shown in the figure.

A step motor is driven according to the speed control pulse signal. Driving methods include turning on and off transistors using speed control pulse signals, and there are also ICs dedicated to driving step motors, and speed control can be easily performed by inputting a pulse signal.

In this way, the fourteenth block diagram can be realized very easily, and by using the step motor drive circuit, the rotational speed of the step motor can be continuously varied over a wide range using an analog input signal. In addition, if a simple voltage divider consisting of a glass-minus reference voltmeter VC and 17 variable resistors as shown in Figure 7 is installed in the analog signal input section, the voltage division ratio can be changed using the variable resistors. Therefore, any rotational speed of the step motor can be obtained instantly.

Also, as shown in Fig. 8, by moving the table 20 using a step motor and a feed screw 25, the position A fixed on the table can be moved to the position X (
t) A circuit (24) that detects the difference (distance) between position A and coordinate x (i) when you want to follow it (changes over time).
If there is, the position A i

With this servo system, the rotation speed is determined by the magnitude of the error signal, so good responsiveness can be expected.

For example, if applied to a head tracking mechanism in a servo type all-optical disk drive, a step motor, which is a low-contact actuator, can be controlled with high precision.

[Effect of the invention 1] As described above, Hontakuma makes it possible to control the rotation speed and rotation direction of the step motor by analog signals without using an A/D K converter, and also to control the rotation speed and rotation direction of the step motor. f can be changed continuously over a wide speed range very easily.

Further, the step motor drive circuit of the home-to-house speed control method can be realized extremely easily and inexpensively by using an absolute value amplifier, a Vf converter, a comparator, etc., and the device is also compact.

Furthermore, this speed control method can be easily applied to servo systems, and closed-loop control using a step motor can be easily realized, so it can be applied to small precision equipment such as magnetic memory and original memory.

[Brief explanation of the drawing]

FIG. 1 is a block diagram of a step motor drive circuit of the present invention. Figure 2 shows a conventional step motor r! ! A motion circuit block diagram. FIG. 5 is a circuit diagram showing an example of an absolute value amplifier. FIG. 4 is a block diagram showing the principle of an example of a Vf converter. FIG. 5 is a circuit diagram showing an example of a speed control pulse signal home generator. FIG. 6 is a time chart showing the operation of the pulse signal generator of FIG. 5. FIG. 7 is a circuit diagram using the output of a voltage divider as an input signal. FIG. 8 shows the step motor driving circuit of the present invention.
A block diagram applied to a simple positioning servo. 1.8... Input (control signal) 2... Absolute value amplifier 5... Voltage-frequency conversion circuit 4...
...Comparator 5 for positive/negative judgment...
・Speed control pulse generator 6.10, 19.22...
Step motor drive (Circuit 7.11.21...Step motor 9.18...Pulse signal generator or above Applicant Seiko Epson Corporation and one other person 1 figure, 5'' times-V. mouth

Claims (1)

[Scope of Claims] (a) A step motor drive circuit having a pulse signal generation circuit for controlling rotational speed and a circuit for driving a step motor, and (b) a speed control pulse signal generation circuit having an analog signal input section. , the magnitude of this analog input signal (
(c) A circuit that determines whether the input signal is positive or negative. (d) A voltage-frequency conversion circuit that outputs a pulse signal with a frequency proportional to the absolute value of the analog signal. (e) The pulse signal. 1. A step motor drive circuit comprising: a circuit for obtaining a speed control pulse signal for controlling the rotation speed and direction of the step motor based on the output from the circuit for determining whether the input signal is positive or negative.