JPH0546795B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Application of the Invention] The present invention relates to a rotation speed control device for a plurality of DC motors, and particularly to a control device for a plurality of DC motors suitable for use in a copying machine or the like.

[Background of the invention]

Conventionally, the number of pulses generated by multiple encoders attached to a motor was the same, so for example, if the set rotation speed of one was twice that of the other, the frequency of the output encoder would be It has doubled. Since the rotation speed of multiple motors is detected by switching one counter, the rotation speed detection time of a motor with a low frequency is twice as long as that of a motor with a high frequency, and the detection time of other motors is taken by that amount. When controlling multiple motors, the control time for multiple motors is different, and the control of each motor is not the same, resulting in control delays due to large rotational speed fluctuations, load fluctuations, etc. This has the disadvantage that the control device has poor tracking performance such as a decrease in rotational speed.

[Purpose of the invention]

This invention is a DC motor multiple control device that makes the control time of multiple motors approximately the same by making the output frequency of the encoder approximately the same, and has good followability and can provide approximately the same performance for multiple motors. is to provide.

[Summary of the invention]

The purpose of the present invention is to select and use encoders so that the output frequencies of the encoders are substantially the same even at preset rotational speeds of a plurality of motors.

[Embodiments of the invention]

The operation of the control device of the present invention will be explained with reference to FIG. In this example, three motors M _A , M _B ,
This is for the case where the rotation speed of M _C is controlled at the same time. Encoders E _A , E _B , and _EC are attached to the motors M _A , M _B , and _MC in correspondence with each other, respectively. As the motor rotates, the encoder outputs a signal with a frequency proportional to the number of rotations, as shown in the example shown in FIG. 2 _EA . DS is a data selector and the control unit CTRL in the overall control unit MPU
One signal is selected from among the signals in encoders E _A , E _B , and E _C according to the signal shown in Fig. 2.
As shown by INT, a pulse signal synchronized with the rising edge of the encoder signal is output to the control unit CTRL as an interrupt signal INT.

The overall control unit MPU compares the preset rotational speed value of each motor with the actual rotational speed measured from the encoder signal coming in through the DS, and determines whether the actual rotational speed is the preset rotational speed. The motors E _A , E _B , E _C are always the same.
Outputs duty data for energizing the motor to the driver devices DRIVA, DRIVB, and DRIVC. DRIVA to DRIVC turn on transistors Q _A , Q _B , and Q _C for a certain period of time according to data from the overall control unit MPU.

In this way, the rotational speed of motors M _A to M _C is controlled by the "on" time of Q _A to Q _C , that is, the duty value. For example, if the rotation speed of motor E _A is lower than the preset rotation speed,
The MPU outputs a data value to DRIVA that causes Q _A to be "on" for a longer period of time, causing motor E _A to increase its rotational speed. Here, V is a motor drive power source.

Here, the encoder frequency combinations of the present invention will be explained in detail. First, a method for detecting the motor rotation speed will be explained with reference to FIG. It is now assumed that the data selector DS has selected the encoder E _A signal. The data selector DS outputs a pulse signal INT synchronized with the rising edge of the _EA signal to the control unit CTRL in the MPU as an interrupt signal. The CTRL section calculates the time from the first INT signal to the second INT signal by counting the number of pulses from the oscillator CK (for example, composed of a crystal oscillator X, etc.).
Measured at CNTR. Although this time is inversely proportional to the rotation speed of the motor, the rotation speed of the motor can be measured by measuring the time. After measuring the rotation speed of motor M _A ,
CTRL then outputs a signal to DS to select encoder E _B , and in the same manner as above, motor
The rotation speed of motor M _B is measured, and then the rotation speed of motor M _C is measured in the same manner. The measured rotation speed and the preset rotation speed are compared by the calculation unit ALU, and an "on" time data value for each motor is output.

In this way, the rotation speed is measured by sequentially switching multiple encoder E _A - _{E C} signals, so if the frequencies of the E _A , E _B , and E _C signals are different, the interval t between the INT signals will be different, so each motor The time it takes to detect the rotational speed of the two will be different.

Also, as shown in Figure 3, the interrupt signal INT is E _A ,
It is generated by the rising edge of E _B , E _C , and E _A , E _B ,
Since the E _C signals are not synchronized, for example, even if the E _B signal is selected with the E _B selection signal, the INT signal will be delayed by the time between INT and INT due to E _B , as shown in the figure. Become. In other words, twice the time t between INT and INT is required.

In this way, for example, when the encoder frequency is halved, the time required to measure the rotational speed also doubles, and this time causes a control delay.

According to the present invention, since the frequencies of the encoders E _A , E _B , and E _C are selected to be almost the same for the preset rotation speed, INT to INT
The time t between these two motors is approximately constant, and the control time for each motor is constant, making it possible to perform stable control with little variation in rotational speed and quick response.

Also, since the input signal INT signal to CTRL is an interrupt signal, the MPU inputs the first INT signal and the second INT signal.
Since the rotation speed is measured by comparing the CNTR value when the INT signal is input for the second time, another control can be performed when the INT signal is not input.

Furthermore, if the preset rotation speed is doubled, for example, the INT signal will be
It will come in at 1/2 the time, but in this case, count the INT signal, detect the rotation speed from the 1st to the 3rd INT time, and at almost the same time, Rotation speed detection becomes possible.

〔Effect of the invention〕

The present invention includes a plurality of DC motors, an encoder attached to the motor shaft of the DC motor,
A data selector that selects the encoder signal of each encoder, a drive device provided corresponding to each DC motor, and a data selector that selects the encoder signal of each encoder;
It is equipped with one control device that controls the motor, and one counter that selects and detects the encoder signal of each encoder via a data selector, and sequentially detects the encoder signal of each encoder and outputs the encoder signal of each DC motor. In a multiple DC motor control device that controls each DC motor to operate at a set rotational speed, each encoder installed on each DC motor has almost the same output even though the set rotational speed of each DC motor is different. each so that a frequency encoder signal is obtained.
An encoder is selected that takes into account the set rotational speed of the DC motor, and the output of the data selector that selects each encoder signal is used as an interrupt signal that can be interrupted to the control device. The feature is that the set rotational speed is controlled by measuring the time between signals.

This configuration has the following advantages.

(1) Each encoder installed on each DC motor is designed so that the set rotational speed of each DC motor can be obtained so that encoder signals with almost the same output frequency can be obtained even though the set rotational speed of each DC motor is different. Selecting an encoder.

In other words, an encoder used for a DC motor with a low set rotation speed will be used for a DC motor with a high set rotation speed.
It uses an encoder that outputs more encoder signals than the encoder used for DC motors. If the lower set value is 1/2 of the higher set value, use one that outputs twice the encoder signal. Even at half the rotation speed, the same encoder signal output as the higher motor can be obtained.

In this way, the encoder signals that detect the rotational speed of each DC motor are made to have approximately the same output frequency, so the encoder signals of each encoder are sequentially detected and each DC
Each DC is used to control the motors to operate at their respective set rotational speeds.
It is possible to control the operation of the motor with little rotational fluctuation and good followability.

(2) The output of the data selector that selects each encoder signal is used as an interrupt signal to interrupt the control device, and the time between the first interrupt signal and the second interrupt signal is measured to determine the set rotation speed. Therefore, when no interrupt signal is received, the control device can perform other control operations.

[Brief explanation of the drawing]

The drawings show the configuration of an embodiment of the present invention; FIG. 1 is a block diagram, FIG. 2 is a diagram illustrating the principle of rotational speed measurement of the present invention, and FIG. 3 is a detailed diagram. M _A , M _B , _MC ... Motor, E _A , E _B , E _C ...
Encoder, Q _A , Q _B , Q _C ...transistor,
DRIVA, DRIVB, DRIVC...Drive device, DS...
...Data selector, MPU...Overall control unit,
CTRL...Control unit, CNTR...Counter, ALU
...Arithmetic section, CK...Oscillation section, X...Crystal.

Claims (1)

[Claims] 1. A plurality of DC motors, an encoder attached to the motor shaft of the DC motor, a data selector for selecting an encoder signal of each encoder, and a data selector provided corresponding to each DC motor. a drive device that controls each DC motor, one control device that controls each DC motor, and one counter that selects and detects the encoder signal of each encoder via a data selector, and detects the encoder signal of each encoder. In a multiple DC motor control device that sequentially detects the rotational speed of each DC motor and controls each DC motor to operate at a set rotational speed, each encoder installed on each DC motor is connected to the set rotational speed of each DC motor. Select encoders that take into account the set rotational speed of each DC motor so that encoder signals with almost the same output frequency can be obtained despite the difference in output frequency, and send the output of the data selector that selects each encoder signal to the control device. As an interrupt signal that can be interrupted,
A control device for multiple DC motors, characterized in that the set rotation speed is controlled by measuring the time between the first interrupt signal and the second interrupt signal.