JPS61180587A - Motor rotation state detection circuit - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a circuit for detecting the rotational state of a motor that drives a mechanical device.

Generally, in a mechanical device, the control timing of the mechanical system is regulated by the rotational speed of the drive motor. Therefore, it is necessary to monitor the rotational state of the motor, but there is a particular problem between the time when the motor is started and the time when the motor reaches a steady rotational state.

In other words, when starting a mechanical device, power is applied to the drive motor, the motor starts rotating, and after reaching a predetermined rotational speed, that is, a steady rotation state, various functions are combined and its operation begins. will be done. However, before the motor rotational speed reaches a steady state, the control timing may be out of order, causing damage to the mechanical device.

Therefore, a method for accurately detecting that the motor has reached a steady state using a simple circuit is desired.

[Conventional technology]

Conventionally, after power is applied to the motor and the motor starts,
After a certain period of time had elapsed, it was assumed that the rotation speed had reached a steady state, and the function started operating.

There is no problem if the device is not related to control timing, but such a method is insufficient for a multi-functional and precise device because it requires complicated timing.

[Problem that the invention seeks to solve]

The time it takes for the motor to reach a steady state after power is applied is not necessarily constant. For example, if the power supply voltage drops during that time, it will take longer to reach steady state.
Conversely, if the power supply voltage increases, the time will become shorter.

Furthermore, if the load on the motor is not constant but fluctuates, the time it takes to reach a steady state is indefinite.

Also, even if it enters a stable rotation state after a certain period of time,
There is a problem in that it is necessary to use a separate circuit to detect whether the motor rotational speed is a predetermined rotational speed, underspeeding, or overspeeding.

[Means for solving problems]

In order to solve the above problems, the present invention connects an encoder to a motor, extracts pulse signals proportional to motor rotation, and counts them with a counter.

This counter is reset at precise intervals, so
The number of pulses counted by the counter is a value proportional to the rotation speed of the motor.

By comparing this value with a set value, that is, the number of pulses in a steady rotation state, the rotation state of the motor can be detected.

[Effect]

An accurate period can be obtained by dividing the basic clock pulse, so if you compare the count value of the counter with the set value, which is the predetermined number of rotations of the motor replaced with the number of pulses, you can easily control the motor. The rotation state can be detected, and the circuit configuration with this function is simple.

〔Example〕

Hereinafter, the present invention will be described in detail with reference to the drawings.

FIG. 1 is a block diagram showing an embodiment of the motor rotation state detection circuit of the present invention, and FIG. 2 is an explanatory diagram of the counting operation of the counter 1. In FIG.

For example, an encoder that extracts the intermittent light obtained by rotating a disc having many slits at equal angles between a light source and a photoelectric converter as a pulse signal from the photoelectric converter is connected to the motor, and the encoder is output. Counter 1 counts the pulse signals generated. On the other hand, the reset pulse generation circuit 2 outputs, as a reset pulse signal, a pulse signal obtained by passing the basic clock pulse through a frequency dividing circuit constituted by a flip-flop circuit.

This reset pulse signal serves as a reset signal for the counter 1 and resets the counter 1 at regular intervals.

As shown in FIG. 2, the counter 1 starts counting from the next input pulse of the reset pulse signal. That is, in state (1), the encoder output pulse signal is counted up to n in one period of the reset pulse signal, in state (2), it is counted up to n2, and in state (3), it is counted up to n, and the value of counter 1 is respectively A becomes the first input of the comparison detection circuit 3.

On the other hand, a value obtained by converting the rotation speed of the motor in a steady state into a pulse number is set as a set value B and is used as the second input of the comparison detection circuit 3.

These first and second human forces are compared numerically by the comparison detection circuit 3, and if A<B, it is detected as an under-rotation state, if A=B, it is detected as a steady-rotation state, and if A>B, it is detected as an over-rotation state. Ru.

For example, if the encoder outputs 6000 pulses per revolution, and the steady rotation of the motor is 1000 revolutions per minute,
At this time, 100.000 pulses are output per second.

On the other hand, if the basic clock pulse of 60kHz is divided by 1760 and 10.000 pulses per second are used as the reset pulse,
Counter 1 counts 10 pulses every reset period. That is, the counter is a 4-bit counter that can count up to 16 pulses, and 10 is set as the set value B.

With the above circuit configuration, when the counter count value A is 11 pulses, the motor rotation speed is 1.100 rotations per minute, and when the counter count value A is 9 pulses, the rotation speed of the motor is 900 rotations per minute.

[Effects of the Invention] As explained above, according to the present invention, since the rotational speed of the motor is converted into pulses and the rotational state of the motor is detected at regular intervals, the rotational state of the motor can be detected with a simple circuit configuration. Can be easily detected.

[Brief explanation of drawings]

FIG. 1 is a block diagram of an embodiment of the motor rotation state detection circuit of the present invention, and FIG. 2 is an explanatory diagram of the operating state of the counter. In the figure, 1 is a counter, 2 is a reset pulse generation circuit, and 3 is a comparison detection circuit. Figure 1 Figure 2

Claims (1)

[Claims] a counter that counts pulse signals output from an encoder connected to a motor; a reset pulse generation circuit that resets the counter at regular intervals using a pulse signal obtained by frequency-dividing a basic clock pulse; A motor rotation comprising: a comparison detection circuit that compares a counted value and a predetermined set value, and detects a rotational state of the motor by comparing the counted value of the counter and the set value. Status detection circuit.