JPS63302783A - Speed controller for motor - Google Patents

Abstract

PURPOSE:To enable the constant-speed characteristic of a motor to be kept, by changing a reference speed value based on the comparing result of the detection value of a motor speed with a motor controlling reference value. CONSTITUTION:When a motor speed correcting mode is selected in a standby state, then reference speed voltage data stored in the memory area of a RAM 6 are read out and the output is generated. By an operational amplifier 10, error signal between the reference speed voltage data and motor speed voltage is fed to a drum motor M1. In the meantime, during the lapse of specified time from starting on, pulse from a rotary encoder 1 is counted. When the counting value is smaller than a motor controlling reference value, then a specified value on reference speed data is added, and when the counting value is larger than the reference value, then a specified value is subtracted. The speed correction is performed till the counting value coincides with the motor controlling reference value. In an operation mode, corrected reference speed data is outputted.

Description

DETAILED DESCRIPTION OF THE INVENTION (a) Field of Industrial Application This invention relates to a motor speed control device that performs feedback control so that the rotational speed of a motor becomes a reference speed value.

(b) Summary of the Invention In summary, the motor speed control device according to the present invention includes means for comparing a detected value of the motor speed with a preset motor control reference value. Based on this, the reference speed value in motor feedback control is changed to prevent changes in motor speed due to motor load fluctuations.

(C) Conventional technology When controlling a motor at a constant speed, the rotation of the motor's rotating shaft is transmitted to an encoder or generator to detect the speed of the rotating shaft, and this detection result is used as a preset reference speed. Feedback control is common in which the power is compared and the supplied power is changed so that the error between the two becomes zero. Incidentally, in some copying machines, the scanning of the optical system, the rotation of the photosensitive drum, and the rotation of the paper conveyance device are each driven by separate motors. This eliminates the drive power transmission mechanisms such as gears and clutches that are required to drive everything with one motor, reduces the number of parts, and eliminates deviations in the operating timing of each device due to mechanical wear. It is. When each related device is driven by a separate motor, the rotation of each motor must be maintained to exactly match the speed determined at the design stage in order to synchronize the operation of each device. There must be.

However, even when driving with multiple motors, the load acting on the motors changes due to wear of the bearings due to aging and a decrease in lubricating oil, and the output characteristics of each motor with respect to the applied voltage do not necessarily match the load characteristics. In feedback control that makes the error between the detected value of the motor speed and the reference speed zero, if the load fluctuation becomes large, constant speed characteristics cannot be obtained, and the speed of each motor changes. If such speed changes occur individually in each motor, it becomes impossible to synchronize the operations of the devices driven by the respective motors. Therefore, in the past, a PLLtt4m was used to fix the phase of each motor using a pulse supplied from a clock generator or the like as a reference. This synchronizes the rotation of each motor and accurately synchronizes the operations of each device driven by each motor.

(d) Problems to be Solved by the Invention However, the above conventional motor speed control device using PLL control requires a phase-locked loop for each motor, which has the disadvantage of increasing costs. Ta.

The purpose of this invention is to maintain the constant speed characteristic of the motor by changing the reference speed that is compared with the detected value of motor speed in general feedback control, thereby reducing costs by eliminating expensive control equipment. An object of the present invention is to provide a speed control device that can keep the motor speed constant without causing problems.

(e) Means for Solving Problems The motor speed control device of the present invention compares a detected motor speed value with a reference speed value and performs feedback control of the motor so that the error becomes zero. The speed control device is provided with a comparison means for comparing the detected value of the motor speed and a motor control reference value, and a reference speed value changing means for changing the reference speed value based on the comparison result of the comparison means. It is characterized by

(f1 action In this invention, the detected value of the motor speed used for feedback control is compared with the motor control reference value in the comparison means, and based on the comparison result, the reference speed value in feedback control is set such that the error from the base is 0. Even if the motor is controlled so that the detected value of the motor speed does not match the motor control reference value, the reference speed value changes. If an error occurs, this error is 0
The motor is controlled so that As a result, the detected value of the motor speed differs from the motor control reference value.

(Top Embodiment FIG. 2 is a schematic front sectional view showing the configuration of a copying machine in which a motor speed control device according to an embodiment of the present invention is used.

There is an optical system inside the copying machine main body 21! 23. Copying process device 34 and paper transport device! 35 are provided. The optical system device 23 has a lamp and a mirror, and moves back and forth on the lower surface of the document table 22 in the direction of arrow A or B to scan the document on the document table 22. The copying process device 34 includes a photosensitive drum 24 and a developing device 25.

This photosensitive drum 24 rotates in the direction of arrow C, and the electrostatic latent image formed on its surface is visualized by the developing bag ff25. The paper conveyance device 35 includes paper feed rollers 26a, 26b,
Conveyor belt 27, rollers 28 to 30, and fixing device 31
It is composed of etc. This paper conveyance device 35 guides the paper set in paper cassettes 32a and 32b to a paper discharge tray 33 via a copying process device 34.

The optical system device 23 is equipped with an optical system motor M2, and the rotation of the optical system motor M2 is converted into linear motion by a transmission device (not shown) so that the optical system bag 223 can move back and forth on the lower surface of the document table 22. It is the driving force. Copying process device 34
is equipped with a drum motor M1. This drum motor M
1 is transmitted to the photosensitive drum 24 and the developing device 25, and the rotation of the photosensitive drum 24 and the magnet roller 25a is transmitted to the photosensitive drum 24 and the developing device 25.
It is assumed that the rotational force is Further, the paper transport device W, 35 includes a transport motor M3. The rotation of the conveyance motor M3 is transmitted to the paper feed rollers 26a and 26b, the conveyance belt 27, the conveyance roller 28 30, and the fixing device ff31 via clutches, respectively.

In the copying process, the optical system device 23 starts moving in the direction of arrow A based on the rotation of the photosensitive drum 24, and the paper transport 35 starts transporting the paper. Therefore, in order to faithfully copy the image of the document set on the document table 22, the operations of the optical system device f23, the copying process device 34, and the paper transport device 35 must be synchronized, and the drum motor M1, the optical The rotations of system motor M2 and transport motor M3 must be synchronized.

FIG. 1 is a block diagram of the main parts of the control section of a copying machine equipped with the above motor speed control device.The control section of the copying machine 21 is composed of a main-slave cPU.

Main cptJ (M-CPU) 1 that constitutes the main control unit
constitutes a sub-control unit according to a program written in the ROM 2 in advance.

In addition to the 5-CPU4 shown in the figure, the M-CPUI, which inputs and outputs data with the slave CPU (S-CPU), is connected to the 5-CPUs that constitute other sub-control units. . 5-CPU 4 controls copying process device 34;

That is, the 5-CPU 4 is connected to the drive system of the drum motor M1 via the I10 interface 7. The 5-CPU 4 is also connected to a taratch solenoid drive system and a corona discharger drive system (not shown) via the I10 interface 7. 5-CPU4 is M-CP
Upon receiving instructions from the UI, the drum motor Ml is driven according to a program written in advance in the ROM 5. At this time, a part of the memory area of the RAM 6 is allocated to the working area.

The drum motor M1 is kept at a constant speed by feedback control during driving. Specifically, drum motor M
The pulse frequency (proportional to the speed) of the rotary encoder 11 provided at the rotary encoder 1 is converted into voltage by the F/V converter 8. On the other hand, the 5-CPU 4 outputs reference speed voltage data D. This reference speed voltage data D is transmitted to the D/A converter 9.
is converted into a reference voltage value by The above voltage value of the F/V converter 8 and the reference voltage value of the D/A converter 9 are introduced to the operational amplifier IO that constitutes the differential amplifier circuit, and are passed through the motor driver 12 so that they match. Drum motor M1 is driven.

FIG. 3 is a memory map of the main parts of the memory that constitutes a part of the control section of the copying machine.

In the RAMG constituting the sub-control section, the reference speed output to the D/A converter 9 is stored in the memo♀ and the pulse router speed Vm of the rotary encoder 11 is stored in the CPU 4. 5-CPU4 is idle. In addition, the above 5-C
The configuration of the PU 4 is the same as the configuration of the other 5-CPUs that control the optical system device t23 and the paper transport device 35, respectively, regarding motor speed control.

4 and 5 are flowcharts showing the remaining operations of the control section of the copying machine.

When the power of the copying machine main body 21 is turned on, warming-up is started (nl). When this warming-up is completed (n2), the operator's key input is accepted and the printer waits for the start of the copying process by operating the print switch (n3, n4). , copy magnification, paper size, and copy mode selection.

When the print switch is operated, the drum motor Ml,
[9 The feed motor M3 and the optical system motor M2 are each driven (n5 to n7), and the copying process is executed (n
8). When driving each motor in steps n5 to n7, reference speed voltage data D is output from the 5-CPU that controls each motor. Each motor continues to be driven until the copying process is completed (n9-=n5).
, turn off the motor when the copying process is complete (nlO
) Return to standby state.

When the motor speed correction mode is selected by the operator's key operation in the standby state, the key interrupt process shown in FIG. 5 is executed. That is, the memory area ml of RAM6
・Read out the reference speed voltage data D stored in n.
11), drive the drum motor M1 (n 12),
At the same time, the timer T should be started.13) While the timer T measures the predetermined time, the rotary encoder 1
The number of pulses from 1 is counted by counter C (n14
．． n15), when timer T times up, counter C
Calculate motor speed Vm based on the contents of (n16)
, this calculation result is temporarily stored in the memory area 443 as described above.

After this, the motor control reference value Va stored in ROM5
is read out (nl?) and compared with the motor speed Vm (n18) - in this comparison, the motor speed voltage data D is added by k and the process returns to step n11 (n19→n20).
), on the other hand, if the motor speed Vm is greater than the motor control reference value Va, the reference speed voltage data D is subtracted by a predetermined value and the process returns to step nll (n21→n22). Further, if the motor speed Vm matches the motor control reference value Va, the motor drive is stopped and the process returns to the main routine (n19→n21→f123), and in step n18. n19 and n21 correspond to the comparison means of the present invention, and step n20. Similarly, n22 corresponds to the reference speed value changing means.

As described above, according to this embodiment, when the speed correction mode is selected by the operator's key operation, the number of pulses of the rotary encoder 11 provided in the drum motor M1 is counted for a predetermined period of time by the counter C; Based on the contents of C, the current motor speed Vm of the drum motor Ml is determined. The value of the reference speed voltage data D output to the D/A converter 9 is changed so that this motor speed matches the motor control reference value Va stored in advance in the ROM 5. Operational amplifier 1 that constitutes a differential amplifier circuit depending on the
As shown in FIG. This is the value that is achieved when the motor control reference value Va required to synchronize with the motor is applied with a load W that does not deteriorate over time. In reality, the load acting on the drum motor Ml changes in the range shown in FIG. 6 due to the inertia force at the time of starting the photoreceptor drum 24, etc., and the motor speed V also changes slightly, but such a speed change can be ignored. It can be judged that sufficient constant speed characteristics are obtained. However,
Load W acting on drum motor M1 due to deterioration over time, etc.
When the voltage changes to the load W2, the drum motor M1 will decrease to the speed V- if the reference speed voltage data D at the design stage remains unchanged.In this way, if the motor speed has a large error from the motor control reference value Va, the minimum If the copying machine 21 deviates from the necessary constant speed characteristic range and cannot achieve synchronization with other devices, the copied image formed by the copying machine 21 will deteriorate.

Therefore, when the speed correction mode is executed, the reference speed voltage data D is changed by the above-mentioned comparison means and reference speed value changing means, and the speed-load characteristic of the drum motor M1 is changed to the sixth value.
The state is shown by the dashed line in the figure. As a result, when the load W2 is applied to the drum motor M1, the drum motor M1
The speed of is equal to the motor control reference value Va. Note that when the speed correction mode is selected, similar processing is performed in the sub-control unit that controls the optical system device 23 and the paper transport device 35, and the optical system motor M2 and the transport motor M3
Similarly, the reference speed voltage data D is changed for each motor control reference value to maintain the speed of each motor control reference value.

In this embodiment, the reference speed voltage data D is changed in the speed correction mode using the key interrupt process, but the process shown in FIG. 5 may be executed at a preset timing. Furthermore, the present invention is not limited to copying machines, but can also be implemented in other devices that control a motor at a constant speed.

(h) Effects of the Invention According to the present invention, it is possible to change the reference speed value that is compared with the detected motor speed value in feedback control based on the comparison result between the detected motor speed value and the motor control reference value. can. Thereby, it is possible to correct changes in motor speed due to load fluctuations caused by motor characteristics, and to make the detected value of the motor speed coincide with the motor control reference value.

At this time, the motor speed detection value to be compared with the motor control reference value may be obtained by the same means as the motor speed detection value used in general feedback control (no additional expensive equipment is required). Therefore, the operational accuracy of the device can be improved without increasing the number of parts or increasing costs.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing the main parts of a control section of a copying machine equipped with a motor speed control device according to an embodiment of the present invention, and FIG.
The figure is a schematic front cross-sectional view showing the configuration of the copier, Figure 3 is a memory map of the main part of the memory that constitutes a part of the control unit of the copier, and Figures 4 and 5 are the control of the copier. FIG. 6 is a flowchart showing the operation of the copying machine, and FIG. 6 is a diagram showing the relationship between the speed and load of the motor included in the copying machine. Ml - drum motor, 8 - F/V converter, 9 - D/A converter, 10 - operational amplifier, 11 - rotary encoder, 12 - motor driver. 114! M Figure 5

Claims (1)

[Claims] (1) In a motor speed control device that compares a detected motor speed value with a reference speed value and performs feedback control of the motor so that the error becomes 0, the detected motor speed value and the motor control reference value are A motor speed control device comprising a comparison means for comparison, and a reference speed value changing means for changing the reference speed value based on the comparison result of the comparison means.