JP2002171779A - Rotating and driving device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To stably and precisely control output rotational speed in a rotating and driving device using an elastic body speed reducer. SOLUTION: This rotating and driving device 1, which is a device for rotating and driving a photoreceptor drum of a full-color image-forming device, is provided with a stepping motor 2, the elastic body speed reducer 3, and feedback control means 40, 41, 42, 43. The speed reducer 3, a device that includes a torque-transmitting part that transmits torque by frictional contact of an elastic body but not including a torque-transmitting part by gears, reduces the revolutions of a motor and outputs them to the photoreceptor drum. The feedback control means detects the output rotational speed of the speed reducer 3, to obtain a difference value from a target speed to directly control the rotational speed of the motor by giving a speed command signal to the motor based on the difference value.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a rotary drive, and more particularly, to a rotary drive for rotating a photosensitive drum of a copying machine.

[0002]

2. Description of the Related Art In an image forming apparatus such as a copying machine, a printing machine, and the like, a rotation driving device for rotating a photosensitive drum and a roller for feeding a film at a relatively low speed and high accuracy is required. . Conventional devices of this type include a motor,
A planetary speed reducer for reducing the rotation of the motor. As a planetary speed reducer, there is a speed reducer of a traction type, that is, a friction transmission type.

Here, in a full-color copying machine, for example, a rotary drive device is used to drive a photosensitive drum for each color component. In this case, it is necessary to control the rotation speed of each rotation drive device with high accuracy in order to prevent color shift and color unevenness. In a printing press, this type of rotation drive device is used to feed a film. In order to avoid printing unevenness, it is necessary to control the rotation speed with high accuracy as described above to minimize speed fluctuations. is there.

Therefore, as disclosed in Japanese Patent Application Laid-Open No. H10-215593, the output rotation speed of the reduction gear is detected by a sensor, and based on the detection result, the output rotation speed is always set to a desired rotation speed. An apparatus has been provided in which the rotational speed of a motor is feedback-controlled.

[0005]

In a rotary drive device using a traction reduction device, a rotational force is transmitted by frictional contact between metal members. Therefore, if the feedback control is performed in consideration of only the slip amount of the reduction gear, accurate rotation speed control can be performed. That is, it is not necessary to consider a delay element when controlling the rotation speed. Therefore, in the feedback control of the motor rotational speed, speed control is performed by increasing or decreasing the acceleration (torque) of the motor, which can be configured most easily and at a low cost.

More specifically, in the feedback control using the traction reduction device, first, the output rotation speed of the traction reduction device is detected, and the difference between this rotation speed and the target rotation speed is obtained. Then, according to the difference, the acceleration (torque) of the motor is increased or decreased in consideration of the reduction ratio. In such a control loop, a delay element occurs depending on the stiffness of the members constituting the reduction gear transmission. For example, when the rigidity of the member is extremely low, the member is elastically deformed at the time of transmitting rotation, and this becomes a delay element in the conventional feedback control system. However, as described above, in the conventional traction reduction device, since the rotation is transmitted by frictional contact between the metal members, the delay element as described above can be ignored, and only the slip amount is considered. Accurate feedback control becomes possible.

The applicant of the present invention has developed a cheaper elastic body speed reducer instead of the conventional traction speed reducer, and has already filed an application (Japanese Patent Application No. 2000-307496). This elastic body speed reduction device uses a friction roller composed of a structure such as metal constituting a portion outside a friction contact portion and an elastic body constituting a friction contact portion, instead of a conventional metal friction roller. It is. In this elastic body speed reducer, rotation is transmitted by frictional contact of an elastic body instead of frictional contact between metal members.

In a rotary drive device using such an elastic speed reducer, when the above-described conventional feedback control loop is configured, since the elastic deformation of the components is large, the delay element in the control loop is ignored. It is considered that it is no longer possible, and a so-called over-control state occurs.

This will be described in more detail. When the output rotation speed of the reduction gear is smaller than the target value, the feedback control system acts to increase the rotation speed of the motor. However, since this rotation speed increasing effect is released only when the output rotation speed of the reduction gear reaches the target value, the control delay occurs when a delay element (specifically, an elastic body in the reduction gear) exists in the control loop. Occurs, and the output rotation speed of the reduction gear increases beyond the target value, resulting in a so-called overshoot state. At that time, the whole system acts in the direction of decreasing the motor speed, but this control also operates beyond the target value due to the delay element, and as a result, the output rotation speed of the reduction gear Will vibrate.

An object of the present invention is to make it possible to control the output rotational speed stably and accurately, particularly in a rotary drive device using an elastic body speed reducer. Another object of the present invention is to make it possible to adjust inexpensively and stably the rotation fluctuation which causes color shift and color unevenness of each color image carrier of a full-color image forming apparatus.

[0011]

According to a first aspect of the present invention, there is provided a rotary drive device for rotating a driven device, comprising a motor as a rotary drive source, an elastic body speed reducer, and feedback control means. ing. The elastic body reduction device includes a torque transmission unit that transmits torque by frictional contact of the elastic body and does not include torque transmission by gears, and reduces the rotation of the motor and outputs the rotation to the driven device. The feedback control means detects the output rotation speed of the elastic body deceleration device, obtains a difference value from the target speed, gives a speed command signal to the motor based on the difference value, and directly controls the rotation speed of the motor.

In this device, the rotation of the motor is reduced by the elastic body reduction device and output to the driven device. At this time, the output rotation speed of the elastic body speed reducer is detected by the feedback control means, a difference between the detected value and the target speed is obtained, and a motor speed command signal is created based on the obtained difference value. Directly controls the rotation speed of the motor. In this case, the control input to the motor is a parameter directly corresponding to the rotation speed of the motor,
This control input directly controls the rotation speed of the motor.

Here, unlike the conventional feedback control in which the acceleration of the motor is increased or decreased, a speed command signal is given to the motor to directly control the rotation speed of the motor. That is, feedback control is performed using the rotation speed of the motor itself as a proportional element. Therefore, even when the elastic body speed reducer is used, the influence of the delay element due to the elastic body inside the speed reducer is eliminated, and the rotation speed of the motor can be controlled stably and accurately. It should be noted that this elastic body speed reducer does not include a torque transmission unit using gears. This is because, when this is included, rotational unevenness occurs on the output side of the reduction gear due to a shift in engagement caused by the accuracy of the gear.

According to a second aspect of the present invention, there is provided a rotary driving device.
In the apparatus, the feedback control means includes an output rotation sensor, a first conversion section, a first difference detection section, and a signal generation section. The output rotation sensor detects the rotation speed of the elastic body reduction device. The first converter converts the sensor output into a signal. The first difference detector detects a difference between the signal value converted by the first converter and a signal value corresponding to the target speed.
The signal generation unit generates a motor speed command signal for directly controlling the rotation speed of the motor based on the output of the first difference detection unit.

In this device, the rotation speed of the elastic body speed reducer is detected by the output rotation sensor, and the detected value is converted into a signal such as a voltage by the first converter. Then, a difference between the signal value converted by the first conversion unit and the signal value corresponding to the target speed is obtained by the first difference detection unit, and a motor speed command signal is generated based on the obtained difference value. .

Here, as described above, since the rotation speed of the motor is directly controlled by the motor speed command signal, the influence of the delay element in the elastic body reduction device can be eliminated.

According to a third aspect of the present invention, there is provided a rotary drive device.
Alternatively, in the apparatus of the second aspect, the driven apparatus is an image carrier incorporated in a two-color or multi-color image forming apparatus having more than two colors. This rotary driving device is used to drive an image carrier incorporated in a two-color or multi-color image forming apparatus, so that the image carrier is driven accurately and stably, and Color shift is less likely to occur.

According to a fourth aspect of the present invention, there is provided a rotary driving device.
Or in the device of 3, the motor is a stepping motor. The signal generation unit of the feedback control unit outputs a signal directly corresponding to the set rotation speed to the motor based on the output of the first difference detection unit, and a motor control unit based on the output signal from the adjustment unit. And a pulse generating unit for outputting a pulse signal for use.

In this device, a signal such as a voltage directly corresponding to the rotation speed of the motor is output from the adjustment unit based on the output of the first difference detection unit, and a pulse signal for motor control is output based on the output signal. Then, the stepping motor is driven to rotate.

Here, since the stepping motor is used as the motor as the rotation drive source, the rotation speed of the motor can be directly controlled with a simple configuration. According to a fifth aspect of the present invention, in the rotary drive device according to the second or third aspect, the motor is a DC motor. The signal generation unit of the feedback control unit outputs a signal corresponding to a rotation speed set to the motor based on an output of the first difference detection unit, and a motor that detects an output rotation speed of the DC motor. An output rotation sensor, a second conversion unit that converts the output of the motor output rotation sensor into a signal, and a second difference that detects a difference between the signal value converted by the second conversion unit and the output signal value of the first adjustment unit. A detection unit; and a second adjustment unit that outputs a motor rotation control signal based on an output signal from the second difference detection unit.

In this device, a signal such as a voltage corresponding to the rotation speed of the motor is converted to a first signal based on the output of the first difference detector.
Output from the adjustment unit. On the other hand, the output rotation speed of the DC motor as a rotation drive source is detected by a motor output rotation sensor, and this detection output is converted into a signal such as a voltage by a second converter. Then, the difference between the converted signal value and the output signal value of the first adjustment unit is obtained by the second difference detection unit. Based on the output signal from the second difference detection unit, the rotation control signal of the DC motor is calculated. Output from the second adjustment unit.

Here, since a DC motor is used as the motor, the cost is reduced. In addition, the minor feedback control loop including the DC motor, the motor output rotation sensor, the second conversion unit, the second difference detection unit, and the second adjustment unit does not have a delay element such as an elastic body reduction device. Therefore, stable and inexpensive rotation control can be performed.

According to a sixth aspect of the present invention, there is provided a rotary driving device.
The motor is an outer rotor type motor having a stator and a rotatable rotor arranged on the outer periphery of the stator.

In this device, since the outer rotor type motor is used, the inertia moment of the rotor is increased by the larger radius of the rotor than in the inner rotor type. This is equivalent to an inertia component, that is, a flywheel provided on the motor side of the reduction gear transmission. The rotational energy of the flywheel is, given that the rotational angular velocity of the motor and the moment of inertia of the flywheel are the same,
Compared to the case where a flywheel is provided on the driven device side of the reduction gear, the reduction ratio is twice as large as the reduction ratio. For this reason, rotation fluctuations caused by the motor are less likely to be transmitted to the driven device side, and a more effective flywheel effect on the driven device side can be obtained.

According to a seventh aspect of the present invention, there is provided a rotary drive device for rotating a driven device, comprising a motor as a rotary drive source, a speed reduction device, and feedback control means. The reduction gear does not include a torque transmission unit by gears,
The rotation of the motor is reduced and output to the driven device. The feedback control means detects the output rotation speed of the reduction gear to obtain a difference value from the target speed, and provides a speed command signal to the motor based on the difference value to directly control the rotation speed of the motor.

Here, since the feedback control means directly controls the rotation speed of the motor, even if a delay element exists in the control loop, its influence can be eliminated.
Stable and accurate feedback control can be realized.

[0027] According to the eighth aspect of the present invention, there is provided a rotary driving device.
In the apparatus, the feedback control means includes an output rotation sensor that detects the rotation speed of the reduction gear, a conversion unit that converts the sensor output into a signal, a signal value converted by the conversion unit, and a signal value corresponding to the target speed. And a signal generation unit that generates a motor speed command signal for directly controlling the rotation speed of the motor based on the output of the difference detection unit.

According to a ninth aspect of the present invention, there is provided a rotary driving device according to the seventh aspect.
In the apparatus according to the eighth aspect, the driven device is an image carrier incorporated in a two-color or multi-color image forming apparatus having more than two colors.

[0029]

DESCRIPTION OF THE PREFERRED EMBODIMENTS First Embodiment <Structure> FIG. 1 shows a rotary drive device 1 according to a first embodiment of the present invention. This rotary drive 1 is used in an image forming apparatus 51 as shown in FIG. The image forming apparatus 51 is a so-called tandem type full-color image forming apparatus that multi-transfers a recording sheet to a four-color unfixed visible image and then fixes the recording sheet, and is a photosensitive drum arranged along a sheet conveying path. An image forming unit for each color (Y, M, C, B) including the image carrier 52 (image carrier) and the like is provided. The rotation drive device 1 is provided corresponding to each of the photosensitive drums 52 so as to be able to drive each of the photosensitive drums 52.

The rotary driving device 1 shown in FIG. 1 has a motor 2, a planetary-type elastic decelerator 3 for reducing the rotation from the motor 2 and outputting the decelerated rotation, and an output rotational speed of the elastic decelerator 3. And an output rotation sensor 4 for detection.
The rotation drive device 1 further includes a rotation control unit 5 to which an output from the output rotation sensor 4 is input.

The motor 2 is an outer rotor type stepping motor, and is driven by a signal from the rotation control unit 5 to function as a rotation driving source of the rotation driving device 1. The motor 2 mainly includes a bracket 10, a stator 11, and a rotor 12.

The bracket 10 comprises a cylindrical portion 10a and a flange 10b extending from one end to the outer periphery. The motor 2 is fixed to a side surface of the elastic body speed reduction device 3, and the flange 10 b of the bracket 10 also serves as a side wall of the speed reduction device 3.

The stator 11 has coils and is fixed to the outer periphery of the cylindrical portion 10a of the bracket 10.
The rotor 12 includes a rotary drive shaft 14 and a rotor yoke 15
And a rotor magnet 16. The rotation drive shaft 14 extends inside the cylindrical portion 10a of the bracket 10, and is rotatably supported by the cylindrical portion 10a by a plurality of bearings 18 and 19 arranged in the axial direction. Rotary drive shaft 14
Of the elastic body speed reduction device 3 constitutes a sun roller 20 which is an input part of the elastic body speed reduction device 3. The rotor yoke 15 includes a disk-shaped vertical wall 15a, and a cylindrical annular wall 15b extending from the outer peripheral edge toward the reduction gear 3. The inner peripheral portion of the vertical wall 15a is the rotary drive shaft 1.
4 is fixed to the end. The rotor magnet 16 is
It is a cylindrical member having a plurality of poles arranged in the circumferential direction, and is fixed to the inner peripheral surface of the annular wall 15b. In this manner, the rotor magnet 16 is disposed concentrically opposite the stator 11 in the radial direction.

Further, inside the rotor yoke 15,
An inertia member 17 is fixed between the outer peripheral portion of the vertical wall 15a and the rotor magnet 16. The inertia member 17 is an annular or multiple arc-shaped member, and increases the moment of inertia of the rotor 12 as a flywheel. Although the inertia member 17 is a member separate from the rotor 12, for example, a part of the rotor yoke 15 may be configured to have the same function as the inertia member 17. Further, the inertia member 17 is preferably provided inside the rotor yoke 15 in order not to increase the size of the apparatus.
5 may be provided outside.

In the structure of the rotor 12 described above, since the rotor 12 is of the outer rotor type and the inertia member 17 is added, the moment of inertia of the rotor 12 is relatively large. Further, since the outer rotor type is used, a driving force is generated by the magnetic repulsion at a place where the rotor diameter is large, so that the same torque can be generated with a weaker magnetic repulsion than the inner rotor type motor having the same torque. Therefore, the manufacturing cost can be reduced by using a magnet having a weak magnetic force.

The elastic body speed reducer 3 is of a traction type in which a roller is pressed and driven, and an elastic body is used for a friction contact portion. Further, the elastic body speed reducer 3 does not include a torque transmission unit using gears. This is because, when this is included, rotational unevenness occurs on the output side of the reduction gear due to a shift in engagement caused by the accuracy of the gear. Hereinafter, the structure of the elastic body speed reducer 3 will be described in detail.

The elastic body speed reducer 3 is a differential planetary system for reducing the rotation of the motor 2 to, for example, about 1 rotation / second, and comprises a sun roller 20 and an internal ring 21.
, A plurality of planetary rollers 22, a carrier 23 that rotatably supports each planetary roller 22, and an output shaft 24.

The internal ring 21 has an annular fixed ring 21a and a movable ring 21b, respectively, as shown in an enlarged view in FIG.
b is provided so as to face the planetary roller 22 therebetween. The fixing ring 21a is fixed to the housing 25 so as not to move in the axial direction and the rotation direction. The movable ring 21b is attached to the housing 25 so as to be movable in the axial direction and not to rotate relatively. The facing surfaces of the inner peripheral portions of both rings 21a and 21b are
Each is formed in a tapered shape.

The planetary roller 22 is supported by a rod 28 so as to be cantilevered and rotatable with respect to the carrier 23.
It comprises a metal structure 30 outside the frictional contact portion, and elastic bodies 31a and 31b made of rubber, resin, or a composite thereof constituting the frictional contact portion.

The structure 30 includes a large-diameter roller portion 30a and a small-diameter roller portion 30b. The outer peripheral surface of the large-diameter roller portion 30a faces the outer peripheral surface of the sun roller 20. The small diameter roller portion 30b is formed concentrically with the large diameter roller portion 30a on both side surfaces of the large diameter roller portion 30a. The tapered surfaces formed on the inner peripheral surfaces of the fixed ring 21a and the movable ring 21b face the small-diameter roller portion 30b. A groove having a substantially semicircular cross section is formed on the entire outer peripheral surface of the large-diameter roller portion 30a and the small-diameter roller portion 30b.

Each of the elastic members 31a and 31b is a member having a circular cross section, and has a large-diameter roller portion 30a and a small-diameter roller portion 3.
0b. And the large diameter roller section 3
The elastic body 31a attached to the small roller portion 30b is brought into frictional contact with the elastic body 31a attached to the sun roller 20.
Are in frictional contact with the tapered surfaces formed on the inner peripheral surfaces of the fixed ring 21a and the movable ring 21b.

A compression coil spring 32 is arranged on the side of the movable ring 21b.
2, the movable ring 21b is always urged toward the fixed ring 21a. Thereby, each contact surface between the elastic body 31a of each planetary roller 22 and the sun roller 20 and the elastic body 31a
b and a predetermined pressure contact force is applied to each contact surface between the fixed ring 21a and the movable ring 21b, and each elastic body 31a, 31
b is elastically deformed and pressed against the mating member.

It should be noted that the compression coil spring 32 can be omitted by forming the elastic bodies 31a and 31b mounted on the planetary roller 22 with rubber or the like, which is more easily elastically deformed.

The output rotation sensor 4 has a pulse disk 35 fixed to the side surface of the carrier 23, and a light detector 36 including a light emitter and a light receiver. With such a configuration, the rotation speed of the carrier 23, that is, the output shaft 24 is detected, and the detection result is sent to the rotation control unit 5.

<Feedback Control System> Next, FIG. 4 shows the basic blocks of the feedback control system of the device.
The feedback control system of this device includes an output rotation speed detection unit 40 and a rotation control unit 5, and a control loop includes the motor 2, the elastic body reduction device 3, the output rotation speed detection unit 40, and the rotation control unit 5. Have been. The rotation control unit 5 includes a part of the output rotation speed detection unit 40 and the target speed setting unit 4.
1 and a difference detection unit 42 that calculates a difference between the output value of the output rotation speed detection unit 40 and the value set by the target speed setting unit 41.
And a motor output speed control unit 43 for controlling the motor output speed based on the output value of the difference detection unit 42.

FIG. 5 shows a specific block diagram corresponding to the first embodiment. As is clear from FIG.
The output rotation speed detection unit 40 in the output rotation sensor 4
And a rotation speed / voltage conversion unit 44 for converting a frequency (rotation speed) output from the output rotation sensor 4 into a voltage. The rotation speed / voltage conversion unit 44 is included in the rotation control unit 5. The target speed setting unit 4
Reference numeral 1 denotes a voltage conversion unit that converts given target speed data into a voltage. Further, the motor output speed control unit 43 has a PI operation unit 45 and a pulse generation unit 46. The PI operation unit 45 converts the output of the difference detection unit 42 into an adjustment signal by proportional (P) and integral (I) operations. Further, the pulse generation unit 46 is a PI operation unit 45.
A pulse for driving the stepping motor is generated based on the adjustment signal generated by the control unit.

In the control loop shown in FIG.
The adjustment signal (voltage) output from the operation unit 45 is a voltage signal indicating the motor speed itself. <Operation> Next, the operation will be described.

In the motor 2, when the required electric power is supplied to the stator 11, the rotor 12 is driven to rotate by the electromagnetic action of the stator 11 and the rotor 12. As a result,
The rotation drive shaft 14 rotates, and this rotation is performed by the elastic body reduction device 3.
Is input to This rotation is reduced by a reduction ratio determined by the outer diameter and the inner diameter of each of the sun roller 20, the planetary roller 22, and the internal ring 21.
3 and output via the output shaft 24.

At this time, the carrier 23 is fixed by a pulse plate 35 and a photodetector 36 fixed to the side surface of the carrier 23.
Is detected as a pulse signal, and this pulse signal is output to the rotation control unit 5, and the rotation speed of the motor 2 is controlled by feedback control described below.

First, data on the target output rotation speed (rpm) of the elastic body reduction device 2 is given to the voltage conversion section 41. The voltage conversion section 41 converts this data into a voltage and supplies the voltage to the difference detection section 42. On the other hand, the pulse signal, which is the output of the output rotation sensor 4, is input to the rotation speed / voltage conversion unit 44, where it is converted into a voltage. Then, the difference detection unit 4
In 2, the difference between the voltage value corresponding to the target speed output from the voltage converter 41 and the voltage value of the detected output rotation speed is obtained. Next, an adjustment signal is created by the PI operation unit 45 based on the difference value. The adjustment signal output from the PI operation section 45 is a voltage value having the meaning of the motor speed itself, and a pulse signal corresponding to this voltage value is generated by the pulse generation section 46. Then, the rotation of the stepping motor 2 is controlled by the pulse signal output from the pulse generator 46.

By such feedback control,
The stepping motor 2 rotates at a rotation speed corresponding to the number of pulses generated by the pulse signal generator 46. Here, since the elastic body reduction device 3 performs the torque transmission using the frictional contact between the elastic bodies 31a and 31b, the elastic body is elastically deformed at the time of the torque transmission. Therefore, if the rotational speed of the motor is controlled by increasing or decreasing the conventional acceleration (drive torque), the elastic deformation becomes a delay element, and the motor is over-controlled.

However, in the first embodiment, the output rotation speed of the elastic body speed reducer 3 is detected, and the signal for the speed command given to the motor 2 is adjusted according to the detection result. That is, the rotation speed of the motor 2 is directly controlled. Therefore, even if a delay element is present in the elastic body speed reducer 3, the delay element can be prevented from affecting the feedback control, and accurate and stable rotation control can be performed.

Further, in this rotary drive device 1, since the outer rotor type motor is used, the radius of the rotor 12 is larger than that of the inner rotor type and the inertia member 17 is added. The moment of inertia increases. Further, since the rotor 12 having the flywheel effect is provided on the motor side of the elastic body speed reduction device 3, compared with the case where the rotor 12 is provided on the driven device side,
Rotational energy increases when the reduction ratio is squared, and rotation fluctuations of the motor 2 are hardly transmitted to the photosensitive drum 52 as a driven device, rotation of the photosensitive drum 52 is stabilized, and color unevenness of an image of the image forming apparatus 51 is obtained. Are unlikely to occur.

[Second Embodiment] The pulse generator 46 and the stepping motor 2 in the first embodiment can be replaced with a configuration as shown in FIG.

In the second embodiment shown in FIG. 6, a direct current (DC) motor 2 'is used as the motor. And this D
A motor output rotation sensor 47 for detecting the output rotation of the C motor 2 ', a rotation speed / voltage conversion unit 48 for converting a frequency (rotation speed) signal of the sensor 47 into a voltage, and a PI operation unit in a main control loop There is provided a difference detection unit 49 for obtaining a difference between the output value of the output 45 and the output value of the rotation speed / voltage conversion unit 48, and a PI operation unit 55 for converting the output of the difference detection unit 49 into an adjustment signal by proportional and integral operations. are doing. Other configurations are the same as those of the first embodiment.

The output signal of the PI operation section 45 in the main control loop in the second embodiment is a voltage signal indicating the motor speed itself, as described above. And D
In a minor control loop constituted by the C motor 2 ′, the motor output rotation sensor 47, the rotation speed / voltage conversion unit 48, the difference detection unit 49 and the PI operation unit 55, there is an elastic member such as the elastic member in the elastic member reduction device 3. There is no delay element.
Therefore, the DC motor system (system composed of the members 49, 55, 2 ', 47, 48) including the minor control loop immediately responds to the designated speed from the PI operation unit 45 and generates a motor output corresponding to the designated speed. It will have the function of realizing speed. Thus, the DC motor system is a motor that can be directly controlled at a designated speed, and can realize the same function as the stepping motor of the first embodiment.

As is clear from the above, also in the second embodiment, accurate and stable rotation control can be performed as in the above embodiment. Moreover, an inexpensive DC motor can be used as the motor.

[Other Embodiments] In each of the above embodiments, the elastic body speed reducer is employed as the speed reducer. However, the present invention is similarly applied to a conventional traction type speed reducer based on frictional contact between metal members. Can be applied to

[0059]

As described above, in the rotary drive device of the present invention, since the rotational speed of the motor is directly controlled, an elastic body speed reducer having a delay element therein is used as the speed reducer. However, accurate and stable rotation control can be performed.

[Brief description of the drawings]

FIG. 1 is a sectional configuration diagram of a rotary drive device according to a first embodiment of the present invention.

FIG. 2 is an enlarged partial view of FIG. 1;

FIG. 3 is a schematic diagram of an image forming apparatus using the rotary drive device of the present invention.

FIG. 4 is a basic block diagram of a feedback control system according to the present invention.

FIG. 5 is a specific block diagram of a feedback control system according to the first embodiment of the present invention.

FIG. 6 is a specific block diagram of a feedback control system according to a second embodiment of the present invention.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 rotation drive device 2 motor 3 elastic body reduction device 4 output rotation sensor 5 rotation control unit 40 output rotation speed detection unit 42, 49 difference detection unit 43 motor output speed control unit 51 full color image forming device 52 photosensitive drum

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 2H030 AA01 AB02 AD16 BB02 BB43 BB71 2H035 CB01 CG01 CG03 2H071 CA02 CA05 DA27 DA31 5H550 AA14 DD06 DD07 GG03 JJ24 LL01 PP10 5H607 BB01 BB04 BB10 BB19 BB17 BB19 BB17 BB17 BB17 BB17 BB17 BB17 BB11

Claims (9)

[Claims] 1. A rotary drive device for rotating a driven device, comprising: a motor as a rotary drive source; and a torque transmission unit for transmitting torque by frictional contact of an elastic body, and not including a torque transmission unit by gears. An elastic decelerator that reduces the rotation of the motor and outputs the output to the driven device; a differential value between a target speed and an output rotational speed of the elastic decelerator is detected, based on the differential value. A feedback control means for providing a speed command signal to the motor and directly controlling the rotation speed of the motor. 2. The feedback control means includes: an output rotation sensor for detecting a rotation speed of the elastic body deceleration device; a first conversion unit for converting the sensor output into a signal; A first difference detection unit for detecting a difference between the signal value and a signal value corresponding to the target speed; and a motor speed command for directly controlling a rotation speed of the motor based on an output of the first difference detection unit. The rotation drive device according to claim 1, further comprising: a signal generation unit configured to generate a signal. 3. The rotary drive device according to claim 1, wherein the driven device is an image carrier incorporated in a two-color or multi-color image forming device having more than two colors. 4. The motor according to claim 1, wherein the motor is a stepping motor, and the signal generation section of the feedback control means includes
An adjustment unit that outputs a signal directly corresponding to the set rotation speed to the motor based on the output of the difference detection unit, and a pulse generation unit that outputs a pulse signal for motor control based on an output signal from the adjustment unit. 4. The method according to claim 2, wherein
3. The rotary drive device according to claim 1. 5. The motor according to claim 1, wherein the motor is a DC motor,
A first adjustment unit that outputs a signal corresponding to a set rotation speed to the motor based on an output of the difference detection unit; a motor output rotation sensor that detects an output rotation speed of the DC motor; A second conversion unit for converting an output into a signal, a second difference detection unit for detecting a difference between the signal value converted by the second conversion unit and an output signal value of the first adjustment unit, and the second difference The rotation drive device according to claim 2, further comprising a second adjustment unit configured to output a rotation control signal of the motor based on an output signal from the detection unit. 6. The rotary drive device according to claim 1, wherein said motor is an outer rotor type motor having a stator and a rotatable rotor arranged on the outer periphery of said stator. 7. A rotational drive device for rotationally driving a driven device, which does not include a motor as a rotary drive source and a torque transmission unit by gears, and reduces the rotation of the motor to output the output to the driven device. A device that detects an output rotation speed of the speed reduction device to obtain a difference value from a target speed, and provides a speed command signal to the motor based on the difference value to directly control the rotation speed of the motor. A rotation drive device comprising: a control unit. 8. The feedback control means includes: an output rotation sensor for detecting a rotation speed of the speed reduction device; a conversion unit for converting the sensor output into a signal; and a signal value converted by the conversion unit and a target speed. A difference detection unit that detects a difference from a corresponding signal value; and a signal generation unit that generates a motor speed command signal for directly controlling the rotation speed of the motor based on an output of the difference detection unit. The rotation drive device according to claim 7. 9. The rotary drive device according to claim 7, wherein said driven device is an image carrier incorporated in a two-color or multi-color image forming device having more than two colors.