JPH11146676A - Controller and control method for rotational drive source - Google Patents

Abstract

PROBLEM TO BE SOLVED: To control a rotational drive source to be at a specified rotational speed, and also, transmit the rotation to the target of control through a reduction gear and a transmission means without rotational irregularity, other kinetic irregularity, etc., and besides stably and with high accuracy, and besides, contrive downsizing. SOLUTION: This controller is so arranged as to control a DC motor 9 so that the rotational speed may synchronize with a row of reference pulses and also to transmit the rotation of the target 14 of control through a reduction gear 12 and a transmission means 13, and this is equipped with a rotary encoder 11 which detects the rotational speed, being provided at the rotary shaft of the DC motor 9, a phase sensor 17 which detects the motion, being provided at the mobile part of the control target 14, a frequency difference detector 4 which detects the frequency difference between the row of speed pulses outputted from the rotary encoder 11 and a row of reference pulses, and an output varying means 5 which increases and decreases the rotational speed of the DC motor 9, based on the frequency difference and the phase difference.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image processing machine such as a printing machine, a printer, a copying machine or a photo developing machine, a film processing machine, a recording / recording apparatus, etc., which require high rotational accuracy and excellent rotational stability. The present invention relates to a control device and a control method of a rotary drive source suitably adopted for driving a linear motion or a rotary motion portion in a control target.

[0002]

2. Description of the Related Art Conventionally, as a control device and a control method of the above-mentioned rotary drive source, a device which transmits the rotation of a rotary drive source controlled to constant speed rotation to a control target via a gear type speed reducer has been conventionally adopted. ing.

FIG. 6 is a block diagram showing an example of the configuration of a conventional control device for a rotary drive source. In this example, the rotational motion of a DC motor 49 as a rotary drive source is controlled by a speed reducer 52 constituted by a gear mechanism. And transmitted to the rotating shaft 55 of the control target 54 via the transmission means 53.

[0004] A rotary encoder 51 is provided on a rotating shaft 50 of the DC motor 49.
Are output to the frequency difference detector 44 and the phase difference detector 43. A reference pulse is supplied to the frequency difference detector 44 and the phase difference detector 43, and a clock is supplied to the frequency difference detector 44. The reference pulse is a pulse obtained by dividing a clock output from an oscillator 41 having a crystal oscillator by a frequency divider 42. The frequency divider 42 is driven by a DC motor 49 rotating at a predetermined rotational speed. The clock is frequency-divided based on the detection pulse output from the rotary encoder 51 when the clock is present.

The frequency difference detector 44 detects the frequency difference between the detected pulse train output from the rotary encoder 51 and the reference pulse train by counting the difference between the periods of both pulse trains with a clock, and detects the frequency difference. The corresponding signal is given to the output varying means 45. The phase difference detector 43
Detects a phase difference between the detection pulse and the reference pulse, and supplies a signal corresponding to the phase difference to the output varying means 45. Further, the output varying means 45 adjusts the current flowing to the DC motor 49 based on each signal given from the frequency difference detector 44 and the phase difference detector 43, and increases or decreases the rotation speed. Therefore, in this control device, a rotation speed synchronized with the reference pulse is given to the DC motor 49, whereby the control target 54 is operated so as to rotate at a predetermined rotation speed.

[0006] However, in the conventional control device,
In the transmission system from the DC motor 49 to the control target 54, backlash between various transmission members in the transmission system and other transmission errors and transmission failures cause uneven rotation of the rotary shaft 55 of the control target 54, and particularly the transmission shaft intervenes in the transmission system. Gear type reducer 52
Gives a reliable deceleration transmission with less slippage, but causes a slight change in the angular velocity of the output shaft due to the meshing between the gears and the processing accuracy of the gears, and promotes the occurrence of the rotational unevenness in the control target 54. I have. As long as the transmission error or the transmission failure occurs in the transmission system, no matter how much the rotation accuracy of the DC motor 49 is improved in the control system,
The rotation unevenness cannot be eliminated.

In the case where the object to be controlled is an image processing machine such as a printing machine or a printer, when the rotation unevenness occurs on the rotating shaft of a printing drum for paper or photosensitive paper, the unevenness is transferred to the paper or photosensitive paper. When the control object is a film processing machine and the rotation unevenness occurs on the rotation axis of the film feed roll, the thickness of the obtained film is not sufficient. In the case where the control object is a recording / recording device and the rotation unevenness occurs on the rotation axis of a storage medium such as a tape or a disk, various noises are generated when recording is reproduced from the storage medium. become.

Therefore, in the control device using the gear type speed reducer as described above, in order to reduce the rotational unevenness, a flywheel coaxial therewith is connected to a rotating shaft to be controlled, and the flywheel has a moment of inertia. Conventionally, a method of absorbing the change in the angular velocity generated on the output shaft of the gear type speed reducer has been adopted.

However, when the flywheel is mounted on a rotating shaft of a controlled object that rotates at a low speed to obtain stable rotation, it is necessary to increase the weight and the turning radius of the flywheel as much as possible. However, when the weight and the turning radius of the flywheel increase, the size and weight of the entire apparatus must be increased, especially when the control target needs to repeatedly start and stop. If a large amount of energy and time is wasted to reduce workability and efficiency, and if the controlled object requires delicate speed control such as film processing, the control of the Problems such as deterioration of responsiveness will occur. As a result, even if the flywheel is attached to the rotation shaft to be controlled in the control device, it is difficult to reduce the occurrence of the rotation unevenness to an unacceptable level within the range of the weight and the turning radius that can be adopted in the flywheel. Therefore, it has been difficult to respond to the recent technical demands of high rotational accuracy and high responsiveness.

The above-mentioned prior art is directed to a case where the movable portion to be controlled performs a rotary motion. However, a similar problem also occurs when the movable portion to be controlled performs a linear motion. Due to various transmission errors, transmission failures, and the like on the transmission system including the motion conversion unit from the rotational motion to the linear motion, the movable unit to be controlled may have linear motion unevenness.

[0011]

SUMMARY OF THE INVENTION It is an object of the present invention to control a rotational drive source to a predetermined rotational speed and to control its rotation via a speed reducer and a transmission means so that the control object is free from uneven rotation and other movement. It is an object of the present invention to provide a control device and a control method for a rotary drive source, which can transmit power stably and with high precision, and which can be reduced in size and weight.

[0012]

A rotary drive source control device according to the present invention controls a rotary drive source so that its rotation speed is synchronized with a periodic reference pulse train output from a pulse generation means. A control device configured to transmit the rotation to a control target via a speed reducer and transmission means, a rotary encoder provided on a rotation shaft of the rotary drive source and detecting a rotation speed thereof, and a movable part of the control target. And a phase sensor for detecting the movement thereof, frequency difference detection means for detecting a frequency difference between the speed pulse train output from the rotary encoder and the reference pulse train, and a phase pulse output from the phase sensor and Phase difference detection means for detecting a phase difference from a reference pulse, and a rotation speed of the rotary drive source based on the frequency difference and the phase difference. Is characterized in that an output varying means for increasing or decreasing.

Further, in the method for controlling a rotary drive source according to the present invention, the rotary drive source is controlled so that its rotational speed is synchronized with a periodic reference pulse train output from the pulse generating means, and its rotation is decelerated. In a control method for transmitting to a control target via a machine and transmission means, a frequency difference between a speed pulse train output from a rotary encoder for detecting a rotation speed of the rotary drive source and the reference pulse train is detected, and Detecting the phase difference between the phase pulse output from the phase sensor that detects the movement of the control target and the reference pulse, and increasing or decreasing the rotation speed of the rotary drive source based on the frequency difference and the phase difference. Features.

In the control device and the control method for the rotary drive source, an object whose rotation speed and phase are different from each other is detected, and the rotation speed is rotated at a high speed by a rotary encoder provided on a rotation shaft of the rotary drive source. While the rotation axis of the rotary drive source is detected with high accuracy, the phase is determined by a phase sensor provided in the movable part to be controlled.
Detected for the movable part after deceleration. That is, by feeding back the speed pulse train related to the rotation speed of the rotary drive source and the phase pulse related to the motion of the control target based on the given reference pulse, the rotary drive source is corrected while the phase of the control target motion is corrected. The rotation speed is controlled to a predetermined value, whereby the control target is given an even and stable phase motion, and the effects of various transmission errors and transmission failures occurring in the transmission system are reduced. The speed pulse and the phase pulse to be compared with the reference pulse, in order to prevent a decrease in detection accuracy due to a processing error or an installation error of a sensor wheel or the like in a rotary encoder or a phase sensor as a detecting unit thereof, An averaging process and other correction processes for a plurality of detection values may be performed as necessary so that the error is canceled or reduced.

When a traction drive type speed reducer is used as the speed reducer in the transmission system, the cycle of the angular velocity change on the output shaft is not so small as in the case of the gear type speed reducer. The period also increases. Further, when a worm type speed reducer is adopted as the speed reducer, there is no intermittent mesh between gears seen in a normal gear type speed reducer. The period of the change increases.

[0016]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be specifically described below based on embodiments shown in the drawings. FIG. 1 is a block diagram showing a control device and a control method of a rotary drive source according to an embodiment of the present invention.

In FIG. 1, the rotational motion of the DC motor 9 is transmitted through the traction drive type speed reducer 12 and the transmission means 13 to the rotary shaft 15 of the controlled object 14 at a reduced speed. The rotary encoder 1 is mounted on the rotating shaft 10 of the DC motor 9.
1 is provided and the speed pulse train output from the rotary encoder 11 is given to the frequency difference detector 4,
A phase sensor 17 is provided on a rotation shaft 15 of the control target 14 via a sensor wheel 16, and a phase pulse output from the phase sensor 17 is provided to the phase difference detector 3.

On the other hand, the frequency difference detector 4 and the phase difference detector 3 are provided with a reference pulse train obtained by dividing the frequency of the clock output from the oscillator 1 having the crystal oscillator by the frequency divider 2. The frequency difference detector 4 is provided with a clock. The frequency divider 2 includes a speed pulse output from the rotary encoder 11 when the DC motor 9 is rotating at a predetermined rotation speed, and a phase sensor when the control target 14 is rotating at a predetermined rotation speed. The clock is, for example, 1/40 according to each of the phase pulses output from
The frequency is divided into 96 to form a reference pulse train.

The frequency difference detector 4 detects the frequency difference between the speed pulse train output from the rotary encoder 11 and the reference pulse train by counting the difference between the periods of both pulse trains with a clock. A corresponding signal is provided to the output varying means 5. Further, the phase difference detector 3 detects a phase difference between the phase pulse output from the phase sensor 17 and the reference pulse, and supplies a signal corresponding to the phase difference to the output varying means 5.

The output varying means 5 comprises a charge pump circuit 6, a low-pass filter 7, and a pulse width modulation circuit 8. The charge pump circuit 6 outputs a voltage signal corresponding to each of the signals input thereto, and is supplied to a pulse width modulation circuit 8 via a low-pass filter 7. The pulse width modulation circuit 8 expands or contracts the pulse width of the output pulse train according to the applied voltage signal, thereby increasing or decreasing the current flowing through the DC motor 9 and controlling the rotation speed thereof.

FIG. 2 is a block diagram showing a configuration example of the charge pump circuit and the low-pass filter in the output variable means shown in FIG. In the figure, a low-pass filter 7 includes an operational amplifier AP to which a voltage of 2.5 V is applied to a non-inverting input terminal, a capacitor C for applying a negative feedback to the operational amplifier AP, and a resistor R connected to an inverting input terminal of the operational amplifier AP. The charge pump circuit 6 includes a switch circuit 19 for switching the input voltage to 5 V or 0 V (ground). The low-pass filter 7 may be provided in each of the frequency difference detector 4 and the phase difference detector 3, or may be adapted to each input signal by obtaining any input signal and changing the value of the resistor R. You may be comprised so that output is possible. Note that the low-pass filter 7 may also have an adjusting function for obtaining control stability.

FIG. 3 is a timing chart showing the operation of the phase difference detector shown in FIG. In the figure, in a phase difference detector 3, a reference pulse (a) given from a frequency divider 2 is used.
Are compared with the rising and falling points of the detected phase pulse (b) output from the phase sensor 17.

When the detected phase pulse (b) advances from the reference pulse (a) at the time of rising or falling, the charge pump circuit 6 of the output varying means 5 reduces the rotational speed of the DC motor 9. (Deceleration command) is given. Further, when the detected phase pulse (b) is delayed from the reference pulse (a) at the rising time or the falling time, the charge pump circuit 6 of the output varying means 5 increases the rotation speed of the DC motor 9. A signal (speed increase command) is given.

FIG. 4 is a block diagram showing a configuration example of the frequency difference detector shown in FIG. In the figure, in the frequency difference detector 4, a clock from the oscillator 1 is given to a counter 25, a down counter 30, and a flip-flop circuit 32, respectively. At the reset terminal RES of the counter 25, a rising signal of a speed pulse from the rotary encoder 11, which is detected by the rising circuit 27, is supplied to the delay circuit 28.
Has been given through. The clock count value of the counter 25 is given to a register 26, and a rising signal is given from a rising circuit 27 as a latch signal of the register 26. The count value latched by the register 26 is supplied to the arithmetic unit 29. The arithmetic unit 29 calculates the number of clocks for one cycle of the reference pulse 4096 (= the frequency division ratio of the frequency divider) from the register 2
6 performs an operation of subtracting the latched count value.

On the other hand, the reference pulse from the frequency divider 2 is frequency-divided by a frequency divider 23 and supplied to a rising circuit 24 and a falling circuit 24a. The rising signal output from the rising circuit 24 is given to the preset terminal PRE of the down counter 30, the set terminal S of the flip-flop circuit 32, and the latch circuit 31 as a latch signal. The falling signal output from the falling circuit 24a is used as a reset signal for the frequency difference detector 4.

The operation result of the operation unit 29 is a down counter 3
The signal 0 is supplied to the reset terminal R of the flip-flop circuit 32 when the down counter 30 counts 0. The output signal from the Q terminal of the flip-flop circuit 32 is supplied to the count enable terminal CE of the down counter 30 and one input terminal of each of the AND gates A and B.

A signal indicating positive / negative of the operation result of the arithmetic unit 29 is given to the latch circuit 31. The output of the latch circuit 31 is supplied to the other input terminal of the AND gate A and the AND gate B via the inverter 33. , Respectively. From the AND gate A, a signal (deceleration command) for reducing the rotation speed of the DC motor 9 is output to the charge pump circuit 6 of the output variable means 5, and AND
From the gate B, a signal (speed increase command) for increasing the rotation speed of the DC motor 9 is output to the charge pump circuit 6 of the output variable means 5.

FIG. 5 is a timing chart showing the operation of the frequency difference detector shown in FIG. In the figure, the counter (d) is reset by the rise of the detected speed pulse (c) output from the rotary encoder 11, and the clock counting is started. This count value is latched by the register 26 at the rise of the next detected speed pulse, and is given to the calculator 29. The arithmetic unit 29 calculates the register 26 from the number of clocks 4096 for one cycle of the reference pulse.
Is subtracted, a signal indicating the positive / negative of the operation result is given to the latch circuit 31, and
The absolute value of the operation result is given to the down counter 30.

On the other hand, at the rise of the frequency-divided pulse (a) obtained by dividing the reference pulse (b) by 2 by the frequency divider 23, the down counter 30 is preset and the flip-flop circuit 32 is set. And the latch circuit 31
Latches. After latching, the latch circuit 31 continues to output a signal indicating positive / negative input at that time. That is, the latch circuit 31 continues to output a signal indicating positive when one cycle of the detection speed pulse is shorter than one cycle of the reference pulse, and outputs a signal indicating negative when one cycle of the detection speed pulse is longer than one cycle of the reference pulse. Continues to be output.

When the flip-flop circuit 32 is set, it continues to supply a count enable signal to the down counter 30. The down counter 30 presets the absolute value of the above-described operation result, and while the count enable signal is supplied, Count down from a preset value. When the countdown value reaches 0, the flip-flop circuit 32 is reset, and the count enable signal is not output. That is, while the down counter 30 is counting down, the count enable signal is output.

The positive / negative signal output from the latch circuit 31 is inverted and applied to the AND gates A and B. The ON of the AND gates A and B outputs the count enable signal. Output. Thus, A
The ND gate B outputs a signal (speed increase command) for increasing the rotation speed of the DC motor 9 to the charge pump circuit 6 of the output variable means 5 when the signal indicating positive / negative is negative,
The AND gate A outputs a signal (deceleration command) for reducing the rotational speed of the DC motor 9 to the charge pump circuit 6 of the output variable means 5 when the signal indicating positive / negative is positive.

The frequency difference detector 4 includes a falling circuit 24
The signal a is reset by the falling signal output by the signal a, and the above-described operation is performed every cycle of the pulse obtained by dividing the reference pulse by two.

[0033]

As described above, the control apparatus and the control method of the rotary drive source according to the present invention are configured as described above, so that the rotary drive source is controlled to a predetermined rotational speed and the rotation is controlled via the speed reducer and the transmission means. There is no rotation unevenness or other movement unevenness in the controlled object, transmission can be performed stably and with high accuracy, and furthermore, reduction in size and weight can be achieved. That is, in the present invention,
High-precision phase control of the control target and high-precision speed control with excellent responsiveness of the rotary drive source are performed simultaneously, so transmission errors and power transmission from the rotary drive source to the control target, including the reduction gear, on the transmission system The phase shift of the movement of the controlled object caused by the failure or the like is corrected, whereby the uneven rotation and other uneven movement of the controlled object are eliminated.

In the above, when the speed reducer is a traction drive type speed reducer, the cycle of the angular velocity change on the output shaft is not small as in the case of the gear type speed reducer.
As a characteristic of the traction, the cycle of the rotation fluctuation due to the load also becomes large, and also in the case of the worm type speed reducer, the cycle of the angular velocity change on the output shaft also becomes large. Feedback control becomes relatively easy.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a control device and a control method of a rotary drive source according to an embodiment of the present invention.

FIG. 2 is a block diagram showing a configuration example of a charge pump circuit and a low-pass filter in the output variable means shown in FIG.

FIG. 3 is a timing chart showing an operation of the phase difference detector shown in FIG.

FIG. 4 is a block diagram illustrating a configuration example of a frequency difference detector illustrated in FIG. 1;

FIG. 5 is a timing chart showing an operation of the frequency difference detector shown in FIG.

FIG. 6 is a block diagram illustrating a configuration example of a conventional control device for a rotary drive source.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Oscillator (pulse generation means) 2 Divider (pulse generation means) 3 Phase difference detector (phase difference detection means) 4 Frequency difference detector (frequency difference detection means) 5 Output variable means 9 DC motor (rotation drive source) DESCRIPTION OF SYMBOLS 11 Rotary encoder 12 Reduction gear 13 Transmission means 14 Control object 17 Phase sensor

Claims (4)

[Claims] 1. A rotary drive source is controlled so that its rotation speed is synchronized with a periodic reference pulse train output from a pulse generation means, and its rotation is transmitted to a control target via a speed reducer and a transmission means. In the control device, a rotary encoder provided on a rotation shaft of the rotary drive source and detecting a rotation speed thereof, a phase sensor provided on a movable portion of the controlled object and detecting the movement thereof, and the rotary encoder Frequency difference detecting means for detecting a frequency difference between a speed pulse train output from the reference pulse train and a phase difference detecting means for detecting a phase difference between a phase pulse output from the phase sensor and the reference pulse, Output variable means for increasing or decreasing the rotation speed of the rotary drive source based on a frequency difference and the phase difference. Control device for a drive source. 2. The control device according to claim 1, wherein the speed reducer is a traction drive type speed reducer. 3. The control device according to claim 1, wherein the speed reducer is a worm type speed reducer. 4. A rotary drive source is controlled so that its rotation speed is synchronized with a periodic reference pulse train output from a pulse generation means, and its rotation is transmitted to a control target via a speed reducer and a transmission means. In the control method, a frequency difference between a speed pulse train output from a rotary encoder that detects a rotation speed of the rotary drive source and the reference pulse train is detected, and a phase sensor that detects a motion of the control target is output. Detecting a phase difference between the phase pulse and the reference pulse, and increasing or decreasing the rotation speed of the rotation drive source based on the frequency difference and the phase difference.