JP2006001688A - Drive control device, controlling method, and image forming device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a drive control device for controlling load torque and tensile force of a driving system by adding it to a belt driving system to be driven by drive of a rotor or through the rotor. <P>SOLUTION: This drive control device is formed of a belt mechanism 1 to be driven by a rotary mechanism 8 or through the rotary mechanism, a first motor 5 for driving the rotary mechanism 8 or the belt mechanism 1, a first control unit 13 for controlling the first motor 5 in response to the predetermined target speed or the predetermined target position, and a first motor driver 14 for driving the first motor 5 in response to an output from the first control unit 13. The rotary mechanism 8 or the belt mechanism 1 is provided with a second motor 6 for transmitting driving force separately from the first motor 5. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a photosensitive member (rotating member / belt) drive of an image forming apparatus, an intermediate member (rotating member / belt) drive, an inkjet printer using belt conveyance, other gear transmission systems, light load film and paper conveyance, etc. The present invention relates to a drive control device and a control method for a rotary drive system or a belt drive system driven via a rotary body, and an image forming apparatus provided with these drive control device and control method.

Conventionally, image forming device photoconductor (rotor / belt) drive, intermediate (rotor / belt) drive, inkjet printer using belt conveyance, other gear transmission system, rotation of light load film and paper conveyance, etc. A drive control apparatus and method for driving a body drive system or a belt drive system driven via a rotating body have been proposed (see, for example, Patent Documents 1 to 4).
Patent Document 1 discloses a brandle equipped with an electric motor independent for an entry side roll and an exit side roll, and a line speed control method and apparatus for brandle equipment relating to the speed control of the electric motor.
Patent Document 2 discloses an image forming apparatus provided with a rotational speed fluctuation suppressing means (generator) in order to prevent image deterioration due to speed fluctuation of a toner image carrier (photoconductor).
Patent Document 3 discloses a drive control device that suppresses uneven rotation by adding load generating means (powder brake or hysteresis brake) to a rotational drive system such as a photosensitive drum and a transfer material transport belt drive roller, and an image provided with the drive control device. A forming apparatus is disclosed.
Patent Document 4 discloses an image forming apparatus that has a configuration in which a load different from that at the time of a transfer operation is applied to an intermediate transfer member, and prevents uneven rotation by suppressing load fluctuations.

Patent Document 1 includes an electric motor that is independently driven by the entrance side roll and the exit side roll of the brandle facility, and controls the speed of the electric motor. The speed of the electric motor is controlled so that the tension value of the steel sheet between the entry side roll and the exit side roll is made smaller than the average value of the tension values of the entry side tension facility and the exit side tension facility.
In such a technique of Patent Document 1, the speed of the motors provided on the entry side and the exit side is controlled by a predetermined method, and the remaining one (driven side) motor is used with reference to one of the entry side or exit side motors. The present invention relates to a method and equipment for applying a torque command in consideration of tension applied to a steel plate (feed forward).
However, the Brandle facility, which is a surface treatment facility for steel plates, is a form in which the speed of the electric motors of both rolls on the entry side / exit side of the Brandle facility is controlled. For this reason, in order to control the driven motor, it is necessary to perform torque correction control in consideration of the tension of the steel sheet in addition to speed control, so that complicated control equipment and a control method are required.
In addition, in brand equipment that transports heavy steel plates, it is necessary to control the speed of both rolls because it is necessary to share the force required for transport with both rolls on the entry and exit sides. A complicated device or control method is required as means for generating torque.
Further, in the image forming apparatus, one of the causes of image quality degradation is rotation unevenness of the drive system caused by disturbance applied to the photosensitive member and intermediate member including a rotating member and a belt. The disturbance is a load fluctuation caused by a paper entry at the time of paper feeding or a contact / separation operation of the cleaning device. The load fluctuation is applied as a torque disturbance to the electric motor of the drive system, and causes uneven rotation. As a conventional example to suppress the influence of these disturbances, there is a method of increasing the inertia. However, if the inertia is increased, the entire device becomes larger and heavier, and even if an eccentric component that is a rotational fluctuation component other than the disturbance is suppressed, the target of the drive system There is a problem that the follow-up performance deteriorates.
In particular, in the case of a color image forming apparatus aiming at high speed, there are many cases where a photosensitive body for four colors, one intermediate body, and each drive mechanism are included, and therefore it is desired to downsize each drive system. .
In view of this, the techniques of Patent Documents 2, 3, and 4 have been proposed as methods for improving the problems of the conventional method for increasing the inertia.

According to Japanese Patent Laid-Open No. 2004-228620, in a drive system of an image forming apparatus, a steady load is applied by generating power with a generator attached to the drive system and consuming the power of the generator with resistance. For example, when a disturbance due to paper feeding or the like is applied to the drive system, the rotational speed of the drive system is reduced, and the load generated by the generator is reduced by reducing the amount of power generation. Thereby, the rotation speed due to load fluctuation is suppressed.
However, Patent Document 2 is configured to generate a load torque by moving the drive system. For this reason, it is necessary to move the drive system in order to apply a load for preventing backlash of the gear and making the belt tension constant. Further, in order to control the load torque to be constant, it is necessary to select a resistance value in accordance with the rotational speed.
Patent Document 3 is a technique related to a device that applies a steady load by providing a load control means including a powder brake or a hysteresis brake in a drive control device. As a result, it can be used under conditions with good characteristics of the drive source driven by PWM, and the control performance is improved with respect to load fluctuations.
However, as in Patent Document 2, load torque is generated by the movement of the drive system, as in Patent Document 2, so that a load is applied to prevent backlash of the gear and to keep the belt tension constant. Needs to move the drive train.
In addition, the image forming apparatus disclosed in Patent Document 3 has a configuration in which a load different from that at the time of the transfer operation is applied to the intermediate transfer member, and prevents uneven rotation by suppressing load fluctuations caused by contact and separation of the cleaning device. Like to do.
However, in patent document 3, since it uses a friction member and gives a load mechanically, it is weak with respect to a change with time. In addition, since the load is switched mechanically, the mechanical time constant is slow, and a transient state of the load occurs at the moment of switching, resulting in uneven rotation due to load fluctuations. In addition, there is a problem that it is not possible to cope with fluctuations in the load of paper entry during paper feeding.
Patent No. 3199192 JP 11-119592 A JP 2000-224878 A JP 2002-296872 A

FIG. 8 is a simplified diagram showing main elements of a belt drive control device used in a conventional photosensitive member, intermediate transfer member, and paper transport mechanism of an image forming apparatus. The belt 4 is supported by the driving roller 1, the driven roller 2, and the tension roller 3. By driving the driving roller 1 by the driving motor 5, the belt 4 is driven in a predetermined direction.
The tension roller 3 is supported by an elastic body such as a spring, and is pressed so as to give a predetermined tension to the belt in order to improve the transmission rate of the driving force and prevent the belt from being bent or deviated.
FIG. 8 shows a direct drive type in which no speed reduction mechanism is inserted between the drive motor 5 and the drive shaft, but there is also a type in which a speed reduction mechanism using gears, a timing belt and a pulley is used. As the drive motor 5, a motor capable of changing the speed, such as a motor with a DC brush, a DC brushless motor, or a stepping motor, is used.
FIG. 9 is a simplified diagram showing main elements of a rotary member drive control device used for a photosensitive member and an intermediate transfer member of a conventional image forming apparatus. The driving force generated by the drive motor 10 drives the rotating body 7 via a speed reduction mechanism composed of gears 8 and 9.
Although the speed reduction mechanism of FIG. 9 is based on gears, there is a type of speed reduction mechanism using a timing belt and a pulley. As the drive motor 10, a motor capable of changing the speed, such as a motor with a DC brush, a DC brushless motor, or a stepping motor, is used.
The drive control device shown in FIGS. 8 and 9 is a drive control mechanism that is used under a light load that can drive the device using only the drive motor 5 or the drive motor 10. Other application examples of the image forming apparatus include a production apparatus such as a tape and a film, a driving apparatus, a printing machine, and the like.
Conventionally, in a belt drive control system, a predetermined tension is applied by pressing a rotating body supported by an elastic body such as a spring in order to improve the transmission rate and prevent the belt from bending or shifting.
However, since the spring force is determined by the amount of deformation of the spring, there is a problem that an error from the initial tension occurs when the belt stretches due to a transient state or over time. In addition, since fluctuations in tension also lead to fluctuations in the load on the drive system, rotational speed errors also occur.
Accordingly, an object of the present invention is to provide a drive control for controlling the load torque and tension of the drive system in consideration of the above-described circumstances and added to the belt drive system driven by the rotary body or driven through the rotary body. It is an object to provide an apparatus, a control method, and an image forming apparatus including such a drive control device.

In order to solve the above-described problems, the invention described in claim 1 includes a rotating mechanism or a belt mechanism driven via the rotating mechanism, a first electric motor that drives the rotating mechanism or the belt mechanism, and a predetermined mechanism. A first control unit that controls the first electric motor according to the target speed or target position, and a first motor driver that drives the first electric motor according to the output from the first control unit. The drive control device configured includes a second electric motor that transmits a driving force different from that of the first electric motor to the rotation mechanism or the belt mechanism.
According to a second aspect of the present invention, there is provided a comparing means for comparing a driving torque or driving current of the second electric motor with a predetermined target torque or target current, and a second torque control or current control for the second electric motor. And a second motor driver that drives the second electric motor in accordance with an output from the second control unit.
According to a third aspect of the invention, there is provided target value changing means for changing the target torque or the target current of the second electric motor when a fluctuation occurs in the torque of the first electric motor.
According to a fourth aspect of the invention, there is provided target value changing means for changing the target torque or the target current of the second electric motor when a fluctuation occurs in the speed of the rotating mechanism or the belt mechanism. .
According to a fifth aspect of the present invention, there is provided correction means for correcting an output of the first control unit in accordance with an input to a second control unit that performs torque control or current control on the second electric motor. Features.
The invention described in claim 6 is characterized in that an output of the second electric motor is smaller than an output of the first electric motor.

According to a seventh aspect of the present invention, in the control method for controlling the drive control device according to the second aspect, the predetermined electric motor of the second electric motor is operated so as to act in a direction opposite to the driving direction of the first electric motor. Control is performed so as to set a target torque or a target current corresponding to the target torque.
According to an eighth aspect of the present invention, in the control method for controlling the drive control apparatus according to the second aspect, in the state where the rotation mechanism or the belt mechanism is positioned at a predetermined target position by the first electric motor, Control is performed to set the predetermined target torque or target current of the second electric motor so that a predetermined torque is constantly applied to the rotation mechanism or the belt mechanism.
According to a ninth aspect of the present invention, in the method for controlling the drive control apparatus according to the third aspect, when a fluctuation occurs in the torque of the first electric motor, the target torque or the target current of the second electric motor. Control is performed so as to change.
According to a tenth aspect of the present invention, in the control method for controlling the drive control device according to the fourth aspect, when the speed of the rotating mechanism or the belt mechanism fluctuates, the target torque or the target of the second electric motor. Control is performed so as to change the current.
According to an eleventh aspect of the present invention, in the control method for controlling the drive control apparatus according to the second aspect, the target torque or the target current of the second electric motor is changed in accordance with a target speed of the first electric motor. It is characterized by controlling for use.
According to a twelfth aspect of the present invention, there is provided a control method for controlling the drive control device according to the fifth aspect, wherein the second electric motor is controlled in response to an input to a second control unit that performs torque control or current control. Control which corrects the output of 1 control part is performed.
A thirteenth aspect of the present invention includes the drive control device according to any one of the first to sixth aspects or the control method according to any one of the seventh to twelfth aspects. It is characterized by.

ADVANTAGE OF THE INVENTION According to this invention, the drive control apparatus for controlling the load torque and tension | tensile_strength of a drive system can be provided by adding to the belt drive system driven via a rotation drive system or a rotary body.
It is also possible to provide a control method for controlling a steady load torque and tension by specifying a driving method of the second electric motor, including a control device and a driver for controlling the load torque and tension of the drive system. It becomes possible.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. Here, an embodiment of the present invention will be described focusing on the image forming apparatus. FIG. 1 is a schematic diagram of a belt drive control apparatus according to the present embodiment.
In FIG. 1, a load motor 6 (second electric motor) for applying a driving load is provided on the two driven roller axes of the conventional belt drive control device of FIG. By controlling the driving force generated by the load motor 6, the load or belt tension of the belt drive control device is controlled.
Although FIG. 1 shows a direct drive type in which a speed reduction mechanism is not inserted between the load motor 6 and the driven shaft, a speed reduction mechanism using gears, a timing belt and a pulley may be used.
Since the motor torque is controlled for the load motor 6 and the load torque or belt tension of the apparatus is controlled, a DC brush motor or a DC brushless motor with good controllability is used. In addition to the two types of motors, any motor capable of torque control can be used.
FIG. 2 is a schematic diagram of a rotating body drive control device as the present embodiment. In FIG. 2, a load motor 6 for applying a driving load is provided on the rotating body 7 axis of the rotating body drive control device of the conventional example of FIG.
By controlling the driving force generated by the load motor 6, the load of the rotating body drive control device is controlled. Although FIG. 2 shows a direct drive type in which no speed reduction mechanism is inserted between the load motor 6 and the rotating body shaft, a speed reduction mechanism using a gear, a timing belt and a pulley may be used.
As the load motor 6, a motor with DC brush or a DC brushless motor with good controllability is used because the motor torque is controlled and the load torque of the apparatus is controlled. In addition to the two types of motors, any motor capable of torque control can be used.

Next, motor control will be described. Since the drive control apparatus of FIGS. 1 and 2 is only the difference between the belt and the rotating body, an example in which the belt drive control apparatus is applied to an intermediate transfer body of an image forming apparatus will be described below. In order to simplify the drive control apparatus, the drive motor 5 and the load motor 6 shown in FIG. 1 will be described as DC brush motors.
FIG. 3 is a block diagram showing a speed control system for driving the drive motor at a predetermined speed. FIG. 3 shows a speed control system for driving the drive motor 5 at a predetermined speed.
The target rotational speed of the drive motor (first electric motor) 5 corresponding to the target speed of the intermediate transfer member and the detected drive motor speed are compared by the comparator 12, and the speed deviation is input to the compensator 13. The compensator 13 performs control calculations such as PI and PID, and inputs the output to the first motor driver 14.
The first motor driver 14 detects the motor current, performs an operation for causing the motor current to flow according to the input from the compensator 13, and drives the drive motor 5. The displacement of the drive motor 5 is detected by an encoder (not shown) attached on the motor shaft.
As a method of detecting the speed of the drive motor 5, a method of detecting the motor speed by measuring the pulse interval of the encoder with a reference clock, a method of calculating a difference (differentiation) of displacement obtained from the encoder, a tachometer, There is a method to use.
As the first motor driver 14, in addition to the above-described current drive type driver that passes a motor current corresponding to an input value, a voltage drive type driver that passes a motor voltage equivalent to an input value is used. Here, the speed is detected using the encoder on the drive motor 5 axis, but the belt speed may be detected using the belt encoder provided on the belt 4. In that case, the target speed is the target speed of the belt 4.

FIG. 4 is a block diagram showing a position control system for holding the drive motor at a predetermined position. FIG. 4 shows a position control system for holding the drive motor 5 at a predetermined position.
The target position of the drive motor 5 corresponding to the target position of the intermediate transfer member is compared with the detected drive motor position by the comparator 16, and the position deviation is input to the compensator 17. The compensator 17 performs control calculations such as PID and phase lag advance compensation, and inputs the output to the first motor driver 18.
The first motor driver 18 detects the motor current, performs an operation to flow the motor current according to the input from the compensator 17, and drives the drive motor 5. The displacement of the drive motor 5 is detected by an encoder attached on the motor shaft.
As the first motor driver 18, in addition to the current driving type driver for supplying the motor current corresponding to the input value as described above, a voltage driving type driver for supplying the motor voltage corresponding to the input value is used. Here, the position is detected using the encoder on the shaft of the drive motor 5, but the belt position may be detected using a belt encoder provided on the belt 4. In that case, the target position is the target position of the belt 4. In addition, a control system having a negative speed feedback inside a negative position feedback may be used as the position control system.
When a DC brush motor or DC brushless motor is used and the speed control system or position control system is constructed, a closed loop with negative feedback of speed and position is constructed. However, when a stepping motor is used, it is opened. It becomes the control system of the loop.
The compensators 13 and 17 shown in FIGS. 3 and 4 are constructed by a digital computing unit such as a CPU or DSP, or an analog circuit. The control calculation in the current drive type motor driver 14 is also constructed by a digital calculator or an analog circuit.

FIG. 5 is a block diagram showing a torque control system of the load motor on the driven roller. Since the torque of the drive motor of the torque control system of the load motor (second electric motor) 6 and the current are proportional, FIG. 5 illustrates a case where a target current value corresponding to the target torque is used.
The load target current i _rlm corresponding to the load torque is compared with the motor current i _lm by the comparator 20 and input to the compensator 21. The compensator 21 performs a control operation such as PI, and inputs it to the second motor driver 22.
The second motor driver 22 supplies a motor voltage V _lm proportional to the input to the load motor 6. A voltage that is the difference between the supplied motor voltage V _lm and the motor induced voltage V _elm is input to the motor impedance 23 and becomes a motor current i _lm . The load motor torque T _lm generated by the load motor 6 is a value obtained by multiplying the torque constant K _T by the motor current i _lm in the calculator 24.
When the difference between the load motor torque _Tlm and the drive motor torque _Tdm converted to the load motor shaft is obtained by the adder 29 and divided by the inertia J converted to the load motor shaft by the multiplier 25, the angle on the load motor shaft of the belt drive control device The acceleration becomes _ω′lm , and the value obtained by integrating once by the integrator 26 becomes the angular velocity _ωlm . The motor induced voltage _{V elm} is the form which is multiplied by the multiplier 27 the induced voltage constant _{K E} to the angular velocity omega _lm.
A predetermined load torque or belt tension is applied to the belt drive control device by the load motor torque T _lm generated by the load motor 6. In the rotating body drive control mechanism shown in FIG. 2, in addition to acting as a load torque, it serves as a force for suppressing the backlash of the gear of the speed reduction mechanism.
The compensator 21 in FIG. 5 is constructed by a digital arithmetic unit such as a CPU or DSP, or an analog circuit. The drive control device according to claim 2 is provided with the motor control device described in FIGS. 3 and 5 in the mechanism of FIG. 1 or FIG. The drive control device according to claim 8 is provided with the motor control device described in FIGS. 4 and 5 in the mechanism of FIG. 1 or FIG.
An ink jet printer that includes a belt drive control mechanism in a paper feed mechanism and performs intermittent feed requires high precision paper feed performance. In this belt drive control mechanism, variation in load greatly affects positioning performance or positioning time. The load applied to the belt drive control mechanism is greatly influenced by belt tension.
Therefore, in a state where the rotation mechanism or belt mechanism 4 is positioned at a predetermined target position by the first electric motor 5, the second electric motor is always applied with a predetermined torque to the rotation mechanism or belt mechanism 4. With the configuration in which the predetermined target torque or target current is set to 6, the belt tension is controlled to be constant and the load fluctuation of the mechanical system is suppressed, thereby improving the paper feed positioning performance, thereby improving the image quality. Will improve.

In FIG. 5, by setting the load target current to be positive, the load motor 6 generates a load torque T _lm opposite to the drive torque T _dm generated by the drive motor 5, and T _lm is the load of the belt drive control device. Torque or belt tension.
Load motor 6 of the belt or the rotary body drive control device is driven in the driving torque T _dm direction _{(T dm>} T), it is not necessary to generate a torque for acceleration or deceleration, the load torque T _lm has a drive motor A value smaller than the generated driving torque T _dm is sufficient.
Thereby, compared with the capacity | capacitance of the drive motor 5, the motor with a small capacity | capacitance can be selected for the load motor 6. FIG. Any capacity may be used as long as it can generate the load torque _Tlm .
When transferring an image formed on a photosensitive member or an intermediate body to paper in a belt or a rotating body drive control device of the image forming apparatus, if the paper is supplied to the drive control device, the drive control device has a disturbance torque. Force acts. After that, the paper passes and the disturbance torque disappears to become a steady load torque.
Transient torque fluctuations due to the supply and passage of the paper fluctuate the rotational speed or speed of the drive control system, causing image quality degradation such as color misregistration and white spots. The contact / separation operation of the cleaning device also acts as a disturbance torque.
In the general speed control system shown in FIG. 3, a method is used in which the influence of disturbance is reduced by increasing the gain or the steady-state deviation is suppressed by an integral term. There is also a limit to the increase in the integral term due to stability.
Thus, feed forward in which the driving force of the drive motor is corrected at the timing when the disturbance is applied is also considered, but if the timing at which the disturbance is applied is different from the correction timing, adverse effects will occur.
Therefore, in the present invention, the target value of the load motor is changed in accordance with the speed fluctuation of the drive motor or the belt, and the speed fluctuation is suppressed by controlling the load of the drive control device.

FIG. 6 is a block diagram showing a drive control device that corrects the load target current of the load motor in accordance with the speed fluctuation of the drive motor. Although not shown, if the motor driver of the drive motor is a current drive type driver, the drive motor is torque controlled.
For this reason, an output from the compensator 12 serving as a current command value or a torque command value is input to the load correction calculation unit 30, and the load motor is calculated from the difference between the steady torque and the drive torque of the drive motor having a known predetermined rotational speed. Calculate the torque correction value.
Next, a load target current correction value Δi _rlm converted into a current is obtained, and the adder 31 _{obtains a} load target current i ′ _rlm from the load target current i _rlm and the load target current correction value Δi _rlm, and this load target current i ′. using the _rlm, to generate a load torque _{T lm} load motor 6 by the control system of FIG. In other words, when fluctuations occur in the torque of the drive motor due to disturbance in the drive control system, the drive control can reduce the rotational speed or speed fluctuation by adjusting the load torque or tension with the load motor. An apparatus and a control method thereof can be provided.
When the motor driver 14 of the drive motor 5 is a voltage drive type driver or when the torque command value cannot be detected, the angular velocity ω _dm of the drive motor 5 is input to the load correction calculation unit 30.

一般的に微分や差分演算はノイズが多く含まれるため、ローパスフィルタ処理を行い、動作帯域を制限する。算出した変動トルクΔＴ_ｄｍから負荷モータ６へのトルク補正値を求める。
これを電流換算した負荷目標電流補正値Δｉ_ｒｌｍを求め、補正された負荷目標電流ｉ’_ｒｌｍを使用し、図５の制御系により負荷モータ６に負荷トルクＴ_ｌｍを発生させる。すなわち、駆動制御系に外乱が加わったことにより回転速度もしくは速度に変化が出たとき、負荷用電動機により負荷トルクもしく張力を調整することにより、回転速度もしくは速度の変動を低減できる駆動制御装置およびその制御方法を提供できる。
ここでは、駆動モータ５の角速度から変動トルクΔＴ_ｄｍを算出したが、ベルト表面に設けられたベルトエンコーダの値から速度を算出し、変動トルクを求めても良い。前記負荷補正演算部３０の演算はＣＰＵやＤＳＰ等のデジタル演算器、もしくはアナログ回路によって構築される。
モータの回転数に比例する誘起電圧が発生するため回転数の上昇に伴ってモータ駆動電圧は上昇する。しかし、製品や製造装置のモータ駆動用の電源電圧には限界があり、また、電動機を駆動するドライバにおいても線形性のある領域での使用が制御性から望ましい。
一般的に使用されるＰＷＭ駆動方式のモータドライバでは、モータ駆動電圧が低い領域の線形性能が悪い場合がある。そこで、ベルトもしくは回転体駆動制御装置の駆動モータの目標速度に応じて、図５中の負荷目標電流ｉ_ｒｌｍを変更する。
これによって、負荷トルクもしくはベルト張力が調整され、駆動モータの定常回転時の駆動電圧を電源電圧以下で、かつ、制御性の良い領域に設定することができる。
すなわち、駆動制御系の回転速度もしくは速度の目標値に応じて、負荷用電動機により負荷トルクもしくは張力を調整することにより、駆動用電動機の定常的な駆動電圧の変動を低減できる駆動制御装置の制御方法を提供できる。 Load correction in the calculating unit 30 of the drive motor by multiplying the angular velocity omega _dm drive motor shaft conversion to the derivative or differential of inertia J _dm, calculates the torque fluctuation [Delta] T _dm. The equation is shown in equation (1).

In general, differentiation and difference calculations include a lot of noise, so low-pass filter processing is performed to limit the operating band. A torque correction value to the load motor 6 is obtained from the calculated fluctuation torque ΔT _dm .
A load target current correction value Δi _rlm obtained by converting this into current is obtained, and the corrected load target current i ′ _rlm is used to generate a load torque T _lm in the load motor 6 by the control system of FIG. That is, when a change in rotational speed or speed occurs due to disturbance applied to the drive control system, the drive control apparatus can reduce fluctuations in the rotational speed or speed by adjusting the load torque or tension with the load motor. And a control method thereof.
Here, the fluctuation torque ΔT _dm is calculated from the angular speed of the drive motor 5, but the speed may be calculated from the value of the belt encoder provided on the belt surface to obtain the fluctuation torque. The calculation of the load correction calculation unit 30 is constructed by a digital calculator such as a CPU or DSP, or an analog circuit.
Since an induced voltage is generated that is proportional to the rotational speed of the motor, the motor driving voltage increases as the rotational speed increases. However, there is a limit to the power supply voltage for driving a motor of a product or manufacturing apparatus, and it is desirable from the viewpoint of controllability to use a driver that drives an electric motor in a linear region.
A generally used PWM drive type motor driver may have poor linear performance in a region where the motor drive voltage is low. Therefore, the load target current i _rlm in FIG. 5 is changed according to the target speed of the drive motor of the belt or the rotating body drive control device.
As a result, the load torque or belt tension is adjusted, and the drive voltage during steady rotation of the drive motor can be set to a power supply voltage or less and in a controllable region.
That is, the control of the drive control device that can reduce the fluctuation of the steady drive voltage of the drive motor by adjusting the load torque or tension by the load motor according to the rotational speed of the drive control system or the target value of the speed. Can provide a method.

In the belt or rotating body drive control device of the image forming apparatus, when the image formed on the photosensitive member or the intermediate body is transferred to the paper, when the paper is supplied to the drive control device, the drive control device has a disturbance torque. Force acts. After that, the paper passes and the disturbance torque disappears to become a steady load torque.
Transient torque fluctuations due to the supply and passage of the paper fluctuate the rotational speed or speed of the drive control system, causing image quality degradation such as color misregistration and white spots. The contact / separation operation of the cleaning device also acts as a disturbance torque.
In the general speed control system of FIG. 3, a method of reducing the influence of disturbance by increasing the gain or suppressing the steady-state deviation by an integral term is used. There is a limit, and there is a limit to the increase of the integral term due to stability.
Thus, feed forward in which the driving force of the motor is corrected at the timing when the disturbance is applied is considered, but if the timing at which the disturbance is applied differs from the correction timing, adverse effects will occur.

FIG. 7 is a block diagram showing a drive control device that detects a change in motor torque or a change in current value by a speed control system and a load motor control system. As shown in FIG. 7, the load current deviation i _elm entering the compensator 21 of the control system of the load motor is input to the driving force correction calculation unit 32.
Since the load current deviation i _elm is equivalent to the torque fluctuation amount of the control device, the driving force correction calculation unit 32 uses the driving motor 5 to reduce the torque fluctuation component and the driving motor current correction value Δi corresponding to the torque correction value. _{Calculate rdm} .
Here, it is assumed that the motor driver 14 is a current-driven driver that passes a motor current proportional to the input. The drive motor current command value i _rdm which is the output of the compensator 13 is _corrected by the adder 33 by the drive motor current correction value Δi _rdm and is input to the motor driver 14. As a result, the drive motor 5 generates a torque corresponding to the disturbance to suppress the disturbance and suppress the rotation speed or speed fluctuation.
In the present embodiment, the response time is fast because the load motor control system detects the fluctuation of the motor torque or the fluctuation of the current value. Compared to the case of only the speed control system shown in FIG. Is shortened. Therefore, the image quality is improved. That is, a disturbance is applied to the drive control device, and the applied disturbance is detected from the input to the control unit of the load motor that has changed due to a change in the rotational speed or speed, and the drive force of the drive motor is detected. By correcting the applied disturbance, it is possible to provide a control method for the drive control device that can reduce the rotational speed of the drive control system or fluctuations in the speed.
By limiting the function of the electric motor for controlling the load torque or tension of the drive control system to the generation of the load torque, the capacity of the electric motor for the load can be reduced, and a drive control device having an inexpensive configuration can be provided.
The calculation of the driving force correction calculation unit 32 is constructed by a digital calculator such as a CPU or DSP, or an analog circuit. Although torque interference of the load motor (disturbance torque to the drive motor) occurs on the drive motor side, it is not shown in FIG. Further, the relationship between the speeds of the two motors in the figure is ω _dm = −ω _lm .
According to the present embodiment, the load can be adjusted only by controlling the second electric motor for generating a load regardless of the state of the first electric motor for driving and the control method. The configuration and control method are also simple.
According to the present embodiment, a load can be generated regardless of the state of the drive system. Therefore, even when positioning control for holding at a predetermined position is performed as in the belt paper transport system of an ink jet printer, a predetermined value is applied to the belt drive system. It is possible to continue to apply the tension.

1 is a schematic diagram of a belt drive control device as an embodiment of the present invention. Schematic of the rotary body drive control apparatus as this Embodiment. The block diagram which shows the speed control system for driving a drive motor at predetermined speed. The block diagram which shows the position control system for hold | maintaining a drive motor in a predetermined position. The block diagram which shows the torque control system of the load motor on a driven roller. The block diagram which shows the drive control apparatus which correct | amends the load target electric current of a load motor according to the speed fluctuation of a drive motor. The block diagram which shows the drive control apparatus which detects the fluctuation | variation of a motor torque or the fluctuation | variation of an electric current value by the speed control system and the control system of a load motor. FIG. 6 is a simplified diagram showing main elements of a belt drive control device used in a conventional photoconductor, intermediate transfer member, and paper transport mechanism of an image forming apparatus. FIG. 6 is a simplified diagram showing main elements of a rotary member drive control device used for a photoreceptor and an intermediate transfer member of a conventional image forming apparatus.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Belt mechanism, 4 belt, 5 1st electric motor (drive motor), 6 2nd electric motor (load motor), 7 rotator, 8 rotating mechanism, 13 1st control part (compensator), 14 1st Motor driver, 21 2nd control unit (compensator), 22 2nd motor driver, 30 target value change unit (correction unit), 32 driving force correction calculation unit

Claims (13)

  A rotating mechanism or a belt mechanism driven via the rotating mechanism, a first electric motor that drives the rotating mechanism or the belt mechanism, and a first electric motor that controls the first electric motor according to a predetermined target speed or target position. In a drive control device including a first control unit and a first motor driver that drives the first electric motor in accordance with an output from the first control unit, the rotation mechanism or the belt mechanism includes the first control unit. A drive control device comprising a second electric motor that transmits a driving force different from that of the first electric motor.   Comparison means for comparing the driving torque or driving current of the second motor with a predetermined target torque or target current, a second control unit for torque controlling or current controlling the second motor, and the second The drive control apparatus according to claim 1, further comprising a second motor driver that drives the second electric motor in accordance with an output from the control unit.   3. The drive control device according to claim 2, further comprising target value changing means for changing the target torque or the target current of the second electric motor when a fluctuation occurs in the torque of the first electric motor.   3. The drive control apparatus according to claim 2, further comprising target value changing means for changing the target torque or the target current of the second electric motor when a fluctuation occurs in the speed of the rotating mechanism or the belt mechanism.   3. The drive according to claim 2, further comprising correction means for correcting an output of the first control unit according to an input to a second control unit that performs torque control or current control on the second electric motor. Control device.   The drive control device according to any one of claims 1 to 5, wherein an output of the second electric motor is smaller than an output of the first electric motor.   3. The control method for controlling the drive control device according to claim 2, wherein the target corresponding to the predetermined target torque or the target torque of the second electric motor so as to act in a direction opposite to the driving direction of the first electric motor. A control method characterized by performing control so as to set a current.   3. The control method for controlling the drive control device according to claim 2, wherein the rotation mechanism or the belt mechanism is always set to a predetermined value in a state where the rotation mechanism or the belt mechanism is positioned at a predetermined target position by the first electric motor. A control method comprising: performing control so as to set the predetermined target torque or target current of the second electric motor so that torque is applied.   4. The method for controlling the drive control apparatus according to claim 3, wherein when the torque of the first electric motor fluctuates, control is performed so as to change the target torque or target current of the second electric motor. A control method characterized by the above.   5. The control method for controlling the drive control device according to claim 4, wherein when the speed of the rotation mechanism or the belt mechanism fluctuates, the target torque or the target current of the second electric motor is changed. A control method characterized by the above.   3. The control method for controlling the drive control apparatus according to claim 2, wherein the control is performed to change the target torque or the target current of the second electric motor in accordance with a target speed of the first electric motor. Control method.   6. The control method for controlling the drive control device according to claim 5, wherein the output of the first control unit is corrected in accordance with an input to a second control unit that performs torque control or current control on the second electric motor. A control method characterized by performing control. An image forming apparatus comprising the drive control device according to any one of claims 1 to 6 or the control method according to any one of claims 7 to 12.

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