JPH03256596A - Constant speed operation system for step motor - Google Patents

Abstract

PURPOSE:To realize stabilized constant speed operation by varying the driving pulse rate so that a measured rotational speed matches with a target rotational speed. CONSTITUTION:An actual rotational speed of a step motor 3 detected through a pulse counter 5 is compared with a desired rotational speed at a comparator 6 and a pulse rate for nullifying the error is operated through an appropriate pulse rate operating circuit 7 and fed to a pulse generating circuit 1. The step motor 3 is driven by the output from the pulse generating circuit 1 through a motor drive circuit 2 thus maintaining the rotational speed at a target value.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Application Field) The present invention relates to a constant speed driving device for rotating a step motor in a stable state.

(Prior Art) Conventionally, a device shown in FIG. 2 has been known as a device for rotating a step motor in a stable state. That is, this device outputs a constant pulse signal a calculated from a desired rotation speed from a pulse generation circuit 1 to a step motor drive circuit 2, and converts the pulse signal a into a drive signal in the step motor drive circuit 2. The step motor 3 is rotated by converting the signal and supplying this drive signal to the step motor 3.

(Problem H to be solved by the invention) However, when a step motor is rotated by the conventional device described above, the power supply to the step motor may fluctuate, or the motor and other supporting parts may deteriorate, resulting in fluctuations in rotational speed. When this happens, it becomes difficult to keep the rotational speed of the step motor constant, and it takes time to return to the desired rotational speed.

The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a constant speed driving device that can prevent fluctuations in the rotational speed due to power supply conditions or mechanical disturbances.

(Means for Solving the Problems) A constant speed driving device for a step motor of the present invention converts a pulse signal given from a pulse generation circuit into a drive signal in a motor drive circuit, and rotates a step motor using this drive signal. In the constant speed driving device, a rotational position detection circuit is configured to detect the rotational position of the step motor, and a pulse signal when the step motor rotates is detected based on a device detection signal output from the rotational position detection circuit. a comparator that compares an actual value obtained from the pulse counter with a desired value at a desired rotation speed; and appropriate control of a pulse generation circuit based on a comparison signal obtained from the comparator. The apparatus is equipped with an appropriate pulse rate calculation circuit configured to output a signal.

(Operation) The rotation angle of the step motor is detected by the rotation position detection circuit, and the rotation position of the step motor obtained thereby is outputted to the pulse counter as a position detection signal. This position detection signal and a pulse signal during rotation of the step motor are input to the pulse counter. Then, without waiting for the step motor to rotate once, the actual value of the pulse signal during rotation of the step motor based on this position detection signal is detected. This measured value is input to a comparator, where it is compared with the desired value at the desired rotational speed. As a result, the comparison signal obtained from the comparator is input to the appropriate pulse rate calculation circuit and output as an appropriate control signal to the pulse generation circuit.

Then, the pulse signal generated from this pulse generation circuit is converted into a drive signal by a motor drive circuit, and the step motor is driven by this drive signal.

(Example) Hereinafter, one embodiment of the present invention will be described with reference to the drawings.

FIG. 1 shows the overall output of a constant speed driving device for a step motor.

That is, this constant speed operation device converts a pulse signal a given from a pulse generation circuit 1 into a drive signal S in a motor drive circuit 2, and rotates a step motor 3 using this drive signal S. The device includes a rotational position detection circuit 4, a pulse counter 5, a comparator 6, and an appropriate pulse rate calculation circuit 7.

The rotational position detection circuit 4 is configured to detect the rotational angle of the step motor 3 and output the position as a position detection signal C.

The pulse counter 5 is configured to receive the position detection signal C and the pulse signal a.

Then, a pulse signal a when the step motor rotates three times based on the position detection signal C is outputted as an actual measurement value d. This actual measurement value d is determined because the position detection signal C detects the rotation angle of the step motor 3.
There is no need to wait for the step motor 3 to complete one rotation, and the detection is immediately performed.

The comparator 6 is configured to receive the actual measured value d and a desired value e for obtaining the desired rotational speed. A comparison signal f is output according to the difference between the actual measurement value d and the comparison value e.

The appropriate pulse rate calculation circuit 7 is configured to output an appropriate control signal g to the pulse generation circuit based on the comparison signal f.

Next, the operating state of the step motor 3 by this constant speed driving device will be explained.

First, when the step motor 3 is rotating at a constant rotation speed (desired rotation speed), the actual value d obtained from the pulse counter 5 and the desired value e for obtaining the desired rotation speed match. Therefore, the comparator 6 outputs a comparison signal f for obtaining the desired rotation speed, and the control signal g based on the comparison signal f is output from the appropriate pulse rate calculation circuit 7 to the pulse generation circuit 1. Become. As a result, the rotational speed of the step motor 3 is controlled by the drive signal substantially based on the desired value e.

Next, if the rotation speed of the step motor 3 fluctuates from the desired rotation speed due to mechanical disturbances, power fluctuations, etc., the pulse signal a when the step motor 3 rotates, which is detected based on the position detection signal C, The actual measured value d will fluctuate. As a result, the actual measurement value d obtained from the pulse counter 5
This results in a difference between the desired value e for obtaining the desired rotation speed and the desired rotation speed. Therefore, the comparator 6 determines whether the actual value d is lower than the desired value e (rotation speed has become slower) or higher (rotation speed has become faster), and adjusts the value according to this difference. A comparison signal f is output. And this comparison signal f
A control signal g based on this is output from the appropriate pulse rate calculation circuit 7 to the pulse generation circuit 1. As a result, the rotational speed of the step motor 3 is controlled by a drive signal substantially based on a comparison between the desired value e and the measured value d.

(Effects of the Invention) As described above, according to the present invention, the step motor can be rotated by comparing the desired value and the measured value, and the measured value can be determined without waiting for the step motor to rotate once. Since the step motor is detected, it is possible to quickly recover from changes in rotational speed caused by mechanical disturbances or fluctuations in the power supply that occur in the step motor, and to perform stable constant speed operation.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing the overall output of a constant speed driving device for a step motor according to the present invention, and FIG. 2 is a block diagram showing a conventional constant speed driving device for a step motor. 1... Pulse generation circuit 2... Motor drive circuit 3... Step motor 4... Rotation position detection circuit 5... Pulse counter 6... Comparator 7... Appropriate pulse rate calculation circuit a ... Pulse signal b ... Drive signal C ... Position detection signal d ... Actual value e ... Desired value f ... Comparison signal g ... Proper control signal

Claims (1)

[Claims] 1) A constant speed driving device in which a pulse signal given from a pulse generation circuit is converted into a drive signal by a motor drive circuit, and the step motor is rotated by this drive signal, which controls the rotation of the step motor. A rotational position detection circuit configured to detect a position, a pulse counter configured to detect a pulse signal during rotation of a step motor based on a position detection signal output from the rotational position detection circuit, and a pulse counter configured to detect a pulse signal from the pulse counter. A comparator that compares the obtained actual measurement value with the desired value at the desired rotation speed, and an appropriate pulse rate calculation circuit that outputs an appropriate control signal to the pulse generation circuit based on the comparison signal obtained from the comparator. A constant speed driving device for a step motor, characterized by comprising: