JP2003018880A - Rotating drive and integrated circuit used therefor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To control rotational speed at low cost and with high accuracy. SOLUTION: This device drives an image carrier of an image forming device. The device is composed of a motor 2, a first sensor 3 for detecting the output rotational speed of the motor 2, a reduction gear 4 for decelerating the output shaft rotation of the motor 2, a second sensor 4 for detecting the rotational speed of the output shaft of the reduction gear 4, a second sensor 5 for detecting the rotational speed of the output shaft of the reduction gear, and a controller 6 for receiving detected signals from the first and second sensors 3, 5 and controlling motor rotational speed so that the rotational speed of the reduction gear output shaft is a set speed.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a rotary drive device, and more particularly to a rotary drive device used to drive an image carrier or the like of an image forming apparatus which requires a highly accurate rotation quality at a rotation speed of 200 rpm or less. . The present invention also relates to an integrated circuit used in this rotary drive device.

[0002]

2. Description of the Related Art Excluding some exceptions such as direct drive motors and ultrasonic motors, in order to achieve a rotation speed of 200 rpm or less, considering the efficiency of the motor, the motor must be several times to several tens. It is generally practiced to rotate the motor output at a double speed and then reduce the motor output with a speed reducer to obtain a sufficient torque.

In order to drive an image carrier of an image forming apparatus, which requires a highly accurate rotation quality, a rotary drive unit including a stepping motor and a gear reducer is used, and sometimes the output of the gear reducer is used. The rotation speed is controlled by applying feedback from the shaft. Further, a brushless DC motor and a gear reducer may be used.

As a conventional example of controlling the rotational speed of the final output shaft by utilizing such a brushless DC motor, Japanese Patent Laid-Open Publication No.
There are those disclosed in Japanese Patent Laid-Open No. 2000-231350 and Japanese Patent Laid-Open No. 2000-221858. Then, in both the case of using the stepping motor and the method of using the brushless DC motor,
Flywheels are often used in combination to suppress rotational fluctuations due to gear meshing.

As another example, the applicant of the present invention has proposed a method in which a traction type speed reducer is used and the rotation speed of the output shaft is fed back to perform highly accurate rotation control.

[0006]

In recent years, image forming apparatuses have been required to provide an image carrier with a high speed and full color.
A 4-tandem tandem system with a single unit is becoming mainstream. This four-series tandem system requires four driving sources, and therefore an inexpensive driving device is required. Further, in order to generate a high-resolution image at a low speed and output a large number of sheets in a short time, a driving device is also required to have a wide range of rotational speed for use.

On the other hand, in order to mount four driving devices,
It is necessary to synchronize these four driving devices with high accuracy to eliminate misregistration at the time of superimposing each color element, and at the same time, it is desirable that each driving device is small. However, when using a stepping motor and a gear reducer,
Even if the feedback control is performed based on the rotation speed of the output shaft, there is a problem that the rotation speed range in which the stepping motor itself can be smoothly rotated without vibration is narrow.

Further, since the stepping motor is inefficient, in order to generate the predetermined torque, the power consumption becomes large, and at the same time, the power supply device to be supplied must be upsized. As a result, the amount of heat generated increases, which is inconvenient for configuring the image forming apparatus. On the other hand, in the brushless DC motor and the gear reducer, it is difficult to maintain the state in which the four driving devices are synchronized with each other with high accuracy because the gears change with time even if the flywheel is provided. .

In order to solve the above problems, the final output shaft is controlled as described above.
The devices shown in JP-A-350 and JP-A-2000-221858 have been proposed, but when steady rotation is obtained, the motor alone does not have a function of maintaining speed (switching), so the final output shaft If the torque of the motor is increased or decreased by applying feedback from the above, within the range of non-linear delay elements such as lost motion due to backlash in the reducer,
There was a problem that the motor rotation went up and down so as to run wild, and this operation became a noise.

Further, the present applicant has proposed a method of using a traction type speed reducer and taking feedback from the output shaft. However, although it is small and high-quality rotation can be obtained, a cutting process is required, It was disadvantageous in terms of cost. An object of the present invention is to provide a rotation drive device that is inexpensive and can perform high-precision rotation speed control.

Another object of the present invention is to provide a rotary drive device capable of further suppressing vibration. Yet another object of the present invention is to provide an integrated circuit suitable for a controller of a rotary drive device.

[0012]

A rotary drive device according to a first aspect of the present invention is a device for driving a driven body at a set rotational speed, which comprises a motor as a rotary drive source and an output rotation of the motor. Motor rotation speed detection means for detecting speed,
A speed reducer for decelerating the rotation of the output shaft of the motor, an output rotation speed detecting means for detecting the rotation speed of the output shaft of the speed reducer, and a signal from the motor rotation speed detecting means and the output rotation speed detecting means for deceleration. And a controller for controlling the motor rotation speed so that the rotation speed of the machine output shaft becomes a set speed.

In this device, the output of the motor is decelerated by the speed reducer, and the driven body is driven by the decelerated rotation speed. At this time, the output rotation speed of the motor and the rotation speed of the output shaft of the speed reducer are detected. Then, based on these detected rotation speeds, the rotation speed of the motor is controlled so that the rotation speed of the speed reducer output shaft becomes the set speed.

Here, the feedback control based on the output shaft rotation speed of the reduction gear is performed to try to keep the output rotation speed of the motor constant even if the rotation of the output shaft of the reduction gear is quickly corrected. Since the feedback control works as described above, even if there is a delay element such as lost motion due to backlash in the reducer, there is no problem such as the motor rotating up and down. As a result, the control system does not become disordered, unnecessary noise is not generated,
The rotation speed of the output shaft stabilizes.

A rotation drive device according to a second aspect of the present invention is the first aspect.
In the device, the motor is DC including brassless type
It is a motor. If, for example, a brushless DC motor is used as the motor, smooth rotation can be obtained over a wide range as compared with a stepping motor. Therefore, it is possible to meet the needs of a wide shift range that has been recently demanded.

A rotation drive device according to a third aspect of the present invention is the first aspect.
In the second device, the controller includes a first control unit that receives a signal from the motor rotation speed detection unit to control the motor rotation speed, and a controller that receives a signal from the output rotation speed detection unit to control the motor rotation speed. It has two control parts. Then, the motor, the motor rotation speed detecting means, and the first
The control unit is unitized and configured as a motor unit having a speed maintaining function independently.

Here, in particular, since the motor has a speed maintaining function independently as a motor unit, even if there is a delay element such as lost motion due to backlash in the reducer, the motor rotation is maintained constant. This function eliminates the problem that the motor rotation goes up and down even if feedback control is performed based on the rotation speed of the output shaft. Further, the output shaft rotation speed is stable, as in the device of claim 1.

A rotation driving device according to a fourth aspect is the third aspect.
In the above device, the motor rotation speed detection means has a first sensor for detecting a magnetic change due to rotation of a rotor magnet of the motor, and the first control unit has an output signal of the first sensor corresponding to a set speed of the speed reducer output. The motor is controlled so that there is no deviation with respect to the rotation speed of the motor. This device detects the magnetic change due to the rotation of the rotor magnet in the rotation speed of the motor. Then, the motor rotation is controlled by the first control unit so that the output cycle or frequency of the detection signal has no deviation from the rotation speed of the motor corresponding to the rotation speed of the reduction gear output shaft.

Here, it is not necessary to provide a special sensor for detecting the rotation speed of the motor, and an inexpensive rotation drive device can be realized. According to a fifth aspect of the present invention, in the rotary drive device according to the fourth aspect, the output rotational speed detecting means has a second sensor that outputs a frequency signal proportional to the rotational speed of the output shaft of the speed reducer, and the second controller Controls the motor so that the output signal of the second sensor has a smaller deviation from the set speed of the speed reducer output.

In this device, a frequency signal proportional to the rotation of the output shaft of the speed reducer is obtained by the second sensor, and the rotation speed of the motor is controlled by this. Here, the rotation speed of the speed reducer output shaft can be controlled with high response, together with the control of the first control unit. According to a sixth aspect of the present invention, in the rotation driving apparatus according to the fifth aspect, the deviation between the output signal of the second sensor and the set speed in the second controller is the difference in cycle.

Here, since the amount of the deviation of the speed with respect to the output of the second sensor is represented as the difference of the cycle, the speed deviation can be quickly obtained by one pulse. Claim 7
The rotary drive device according to claim 5 is the device of claim 5, wherein
The deviation between the output signal of the second sensor and the set speed in the control unit is the difference in frequency. Here, since the amount of the deviation between the output of the second sensor and the speed is defined as the frequency difference,
It is possible to digitally determine the velocity deviation that is not affected by the temperature drift of the sensor or the like.

A rotation drive device according to an eighth aspect is the sixth aspect.
Alternatively, in the device of 7, the controller includes, in addition to the first control unit and the second control unit, a third control unit that operates so as to reduce the phase difference between the signal indicating the set speed and the second sensor output frequency signal. I have more. Here, not only speed but also phase can be controlled. Therefore, when it is necessary to drive a plurality of drive devices in synchronization, it is possible to provide a drive suitable for, for example, a four-tandem tandem image forming apparatus.

A rotation drive device according to a ninth aspect is the eighth aspect.
In the device described above, the output rotation speed detecting means includes a second sensor, and N (N is a number of 2 or more) installed at positions substantially evenly divided in the circumferential direction about the output shaft of the speed reducer. It has a sensor. Then, the third control unit cancels a mechanical error of the detected reduction gear output rotation speed around the reduction gear output shaft based on the signals of the N sensors.

In this case, since the synchronization deviation due to the mechanical eccentricity can be canceled, the 4-tandem image forming apparatus can be realized at low cost. According to a tenth aspect of the present invention, in the rotation driving apparatus according to the ninth aspect, the N sensors are two rotary encoders installed at substantially opposite positions on an output shaft that outputs a pulse signal, and the third control is performed. The section cancels a mechanical error around the output shaft of the speed reducer based on the temporal overlap of the output signal pulses of the two rotary encoders.

In this device, the rotation fluctuation of one cycle of the output shaft rotation can be canceled by the minimum necessary sensors (two sensors). The rotary drive device according to claim 11 is the device according to any one of claims 8 to 10, wherein the controller is a first control unit and a second control unit, or a first control unit, a second control unit, and a third control unit. And a single addition / adjustment unit for adding and adjusting the output of each deviation output unit in consideration of a predetermined gain for each of the deviation output units. Outputs a signal that controls the rotation speed.

Here, since it is possible to realize a highly accurate rotary drive device with one adding / adjusting means, it is advantageous in terms of cost. According to a twelfth aspect of the present invention, in the rotary drive apparatus according to the eleventh aspect, the controller has a charge pump circuit for adding / adjusting the output of each deviation output means.

Here, addition of the output of each deviation output means
Since the circuit for adjustment is composed of the charge pump circuit, the gain of each deviation output can be individually set by an inexpensive component such as a resistor as appropriate, so that the controller can be realized cost effectively. According to a thirteenth aspect of the present invention, in the rotary drive device according to any one of the first to twelfth aspects, the reduction gear has at least one set of gears, and the gears are engaged once for one rotation of the motor. However, the phase relationship is set so that the speed fluctuation caused by this meshing and the rotation fluctuation generated in one motor rotation cycle are canceled.

Here, it is convenient that the requirements for the mechanical accuracy of the motor mounting portion can be roughly set. Claim 14
The rotary drive device according to claim 1 is the device according to any one of claims 1 to 13, wherein the reduction gear has a flywheel for suppressing a variation in rotation of the reduction gear output shaft.

Here, it is possible to reduce uncontrollable high-frequency fluctuations, especially speed fluctuations due to meshing of gears of the motor output shaft. According to a fifteenth aspect of the present invention, in the rotary drive device according to the fifteenth aspect, the reduction gear has a reduction mechanism having two or more stages having an intermediate shaft, and the flywheel is installed on the intermediate shaft.

Here, even if the size of the flywheel to be mounted is reduced, it is possible to effectively reduce the speed fluctuation that appears on the output shaft, especially due to the meshing of the motor shaft gears. Claim 1
According to a sixth aspect of the present invention, in the rotation driving device according to any one of the first to fifteenth aspects, the driven body is an image carrier of the image forming apparatus. When the image carrier of the image forming apparatus is driven, highly accurate rotation control is required to realize an image forming apparatus with high image quality, and this apparatus is a device that is convenient for such a requirement.

A rotation drive device according to a seventeenth aspect is the device according to any one of the first to sixteenth aspects, wherein the rotation drive device is provided separately from the output shaft of the reduction gear and connected to the motor, and the rotation speed is not controlled. It further has a second output shaft. Here, a plurality of drives can be realized with one motor. Therefore, the rotary drive device is inexpensive and effective in terms of space utility.

According to an eighteenth aspect of the present invention, in the rotary drive apparatus according to the seventeenth aspect, the output shaft of the speed reducer drives the image carrier of the image forming apparatus, and the second output shaft is other than the image carrier of the image forming apparatus. Drive the driven body of. The image carrier of the image forming apparatus requires high-precision rotation control, but the driven members such as the developing device and the cleaner are not required to have high rotation accuracy. Therefore, in this apparatus, the output shaft of the speed reducer that is in rotation control is used for driving the image carrier, and the second output shaft that is not in rotation control is used for the developing device, cleaner, etc. other than the image carrier. It is used for driving.

An integrated circuit for a rotary drive device according to a nineteenth aspect is an integrated circuit used in a rotary drive device for driving rotation of a driven body at a predetermined set speed. A rotary drive device using this integrated circuit includes a motor as a rotary drive source, motor rotation speed detection means for detecting the output rotation speed of the motor, a speed reducer for reducing the rotation of the output shaft of the motor, and a speed reducer. Output rotation speed detecting means for detecting the rotation speed of the output shaft of the motor and the motor rotation speed so that the rotation speed of the speed reducer output shaft becomes a set speed by receiving signals from the motor rotation speed detecting means and the output rotation speed detecting means. And a controller for controlling. Then, the controller detects the deviation between the signal from the motor rotation speed detection means and the rotation speed of the motor corresponding to the set speed, and the deviation between the signal from the output rotation speed detection means and the set speed. A deviation output unit and an addition / adjustment unit that add and adjust output signals from the first and second deviation output units in consideration of a predetermined gain Is composed of a one-chip integrated circuit.

In this case, since the integrated circuit portion is composed of a one-chip integrated circuit, the control function can be incorporated in the motor board, which is cheaper than a plurality of chips and the motor board is smaller. Can be converted. An integrated circuit for a rotary drive device according to claim 20 is the circuit according to claim 19, wherein the controller is the first and second
In addition to the deviation output unit, a third difference that takes a phase difference between the signal representing the set rotation speed and the signal from the output rotation speed detecting means.
A deviation output unit is further provided, and the third deviation output unit is configured as a one-chip integrated circuit together with the first and second deviation output units and the addition / adjustment unit.

[0035]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS [First Embodiment] <Overall Configuration> FIG. 1 is a block diagram of an image bearing member driving device of an image forming apparatus adopting a rotation driving device according to a first embodiment of the present invention.

This rotary drive device is used for rotationally driving the image carrier 1 of the image forming apparatus, and includes a brushless DC motor 2 as a rotary drive source and a motor 2.
First sensor 3 for detecting the rotation speed of the motor and the motor 2
The gear reducer 4 for reducing the rotation of the gear reducer 4 and the second sensor 5 for detecting the output rotation speed of the gear reducer 4 are included. The gear reducer 4 is, as will be described later, a reducer including a two-stage gear pair. In addition, this rotation drive device sets the target value of the output rotation speed of the gear reducer 4 and inputs the detection signals from the respective sensors 3 and 5, and the motor 6 by the signals from the controller 6. It has a driver 7 to be driven.

The first sensor 3 is disclosed in Japanese Patent Laid-Open No. 10-225081.
It is possible to use an FG sensor such as that disclosed in Japanese Patent Publication. That is, the rotor is used as the FG magnet (frequency generating magnet), and the F is created on the substrate pattern to detect the magnetic change of the rotor rotation.
An AC signal is generated by using a G pattern (conductive pattern), and the rotation speed of the motor as a rotating body can be detected by the level of this frequency.

As shown in FIG. 2, the second sensor 5 can detect a pulse plate 5a having a large number of patterns formed in the circumferential direction and a change in the pattern due to the rotation of the pulse plate 5a. It is composed of a rotary encoder having two sensors 5b and 5c provided at positions facing each other. This rotary encoder is an optical type or a magnetic type.

<Controller> The controller 6 controls the rotation of the motor 2 so that the output rotation speed of the gear reducer 4 reaches the target value by the deviation between the target value and the signals from the sensors 3 and 5. is there. As shown in FIG. 2, the controller 6 includes a first control unit 10, a second control unit 11 and a third control unit 12 and a first control unit 10, 11, 12 which gives a predetermined gain to the outputs of the respective control units 10, 11, 12. First, second and third gain circuits 13, 14, 15 and respective gain circuits 13, 14, 1
Adder / adjuster 16 for adding and adjusting the outputs of 5
And have. Further, a converter 17 for converting the input target set value of the reduction gear rotation speed into the motor rotation speed.
Is provided in front of the first controller 10.

The first control section 10 receives a signal from the first sensor 3 and controls the motor rotation speed.
As shown in (a), it has an F / V converter 10a that receives a signal from the first sensor 3 and performs frequency / voltage conversion, and a first deviation output unit 10b. First deviation output unit 10b
Outputs the deviation between the voltage output from the F / V converter 10a and the voltage value corresponding to the target set value. Here, the target set value is a voltage value corresponding to a value obtained by converting the reducer output rotation speed into the motor rotation speed by the converter 17.

Note that another example of the first control unit 10 is shown in FIG.
It shows in (b). In the example shown in FIG. 3B, the period difference measuring means 10c is provided, and the period difference measuring means 1 is provided.
A pulse signal having a cycle corresponding to the rotation speed, which is the output signal of the first sensor 3, is directly input to 0c, and a cycle corresponding to the target set value is input. The target set value here is a cycle corresponding to a value obtained by converting the reducer output rotation speed into the motor rotation speed. Period difference measuring means 1
0c detects the difference between the cycle of the pulse signal from the first sensor 3 and the cycle of the pulse signal corresponding to the target set value, and outputs a signal corresponding to the cycle difference.

The second control unit 11 receives a signal from the second sensor 5 to control the motor rotation speed, and its configuration is basically the same as that of the first control unit 10. is there. That is, it can be configured by the F / V converter and the deviation output unit or by the period difference measuring means. It should be noted that only the signal from one sensor 5b of the signals from the two sensors 5b and 5c is input to the second control unit 11, and the deviation between this signal and the target value is obtained. . In addition, this second control unit 11
The target set value input to is a voltage value or cycle corresponding to the output speed of the decelerator itself.

The third controller 12 receives the signal from the second sensor 5 and outputs the signal indicating the set target rotation speed and the second signal.
It operates so as to reduce the phase difference from the output signal of the sensor 5, and is composed of a general PLL circuit. Specifically, the detection pulse signals from the two sensors 5b and 5c constituting the second sensor 5 and the pulse signal corresponding to the target set value are input to the third control unit 12, and the third control unit 12 is supplied. Reference numeral 12 detects a phase difference between the average position (average rising edge or average falling edge) of the phase of each detection pulse and the phase of the pulse corresponding to the target set value, and outputs a signal such that these phase differences become zero. To do.

Here, since the third control section 12 performs processing by the signals from the two sensors 5b and 5c, it is possible to cancel the mechanical error around the output shaft of the speed reducer 4. More specifically, for example, the speed reducer 4
When the output shaft or the pulse plate 5a attached thereto is eccentrically attached to the upper side, for example, a number larger than the number of pulses indicating the true angular velocity is provided between the angle 0 to 180 degrees on the upper side of the pulse plate 5a. Pulse (first pulse group: each pulse has a short cycle) is detected. On the other hand, in the lower 180 to 360 degrees, a smaller number of pulses (second pulse group: each pulse has a longer period) than the number of pulses indicating the true angular velocity is detected. The relationship between the cycle of these two pulse groups and the rotation angle is as shown in FIG. That is, it is the detection error of the output shaft 1 rotation cycle component in each sensor.

However, the error of the one rotation cycle component of the output shaft can be offset if the sensor is installed at a position facing the output shaft of the speed reducer. Therefore, a signal representing the target rotation speed is given as a reference pulse so that the cycle of each pulse group is counted and the count value is averaged, and the rising edge of this pulse is 2
By generating a signal for adjusting the speed of the motor so that the pulses output by the individual sensors are at the time center of the pulse, that is, by considering the temporal overlap, the pulse plate 5a or the speed reducer 4 can be controlled. It is possible to cancel the influence of the eccentricity of the output shaft.

This point will be specifically described below.
Up / down counting means (up / down counter) that can be reset at the falling edge of the reference pulse and counts positive and negative absolute values such that it counts up if the pulse from the sensor comes first, and counts down if the reference pulse comes first.
For each of the two sensors. Then, when the count value of each of the two pulses is completed, the count value is added, and if the added value is positive, a deceleration command is output with the judgment that the sensor signal is advancing, and the added value is negative. If there is, the acceleration signal is output on the basis of the judgment that the sensor signal is delayed (the circuit is not shown).

When the pulses from both sensors advance with respect to the rising edge of the reference pulse (see FIG. 6A), both counters have a positive count value, and the added value also has a positive value. Therefore, the deceleration command is output according to the added value when it is determined that the sensor signal is advancing. When the pulses from both sensors are delayed with respect to the rise of the reference pulse (see FIG. 6B), both counters have a negative count value, and the added value also has a negative value. Therefore, when it is judged that the sensor signal is delayed, the deceleration command is output according to the added value. When the pulses from both sensors straddle the rising edge of the reference pulse (see Fig. 6 (c)), both counters have positive and negative numerical values, and the added value is based on the added value. If is negative, the deceleration command is output according to the added value by determining that the sensor signal is delayed, and if the added value is positive, the deceleration command is output according to the added value by determining that the sensor signal is advanced. .

On the other hand, the sensor adds the two signals to obtain the control result, so that even a sudden measurement error (in the case of the optical sensor, an obstacle such as dust) in one sensor is half affected. The effect that becomes is also generated. The gain circuits 13, 14 and 15 give a predetermined gain to the outputs of the first to third control units 10, 11 and 12, respectively. How much gain is given to each output signal It is determined by experiments, etc. In addition, these gain circuits 13, 14, and 15 are resistors R
1, R2, R3.

Further, the addition / adjustment unit 16 includes the control units 1
The deviation output signals from 0, 11, and 12 are added and adjusted to generate a signal for driving a motor, which is configured by a charge pump circuit as shown in FIG. This charge pump circuit 16 has a non-inverting input terminal of 2.5V.
Operational amplifier 20 to which the voltage of
And a capacitor 21 for applying negative feedback to the H signal (5V) or L signal (L) depending on the polarity and amount of the deviation.
Is output. When there is no output, the impedance becomes high.

These functions are deviation processing based on the temporal overlap of the pulses after the up / down means,
The addition of the deviation considering the gain can also be realized by using the CPU. If a high-speed arithmetic means such as a DSP (digital signal processor) is used, it is possible to incorporate not only the function of generating a motor control signal from the added deviation but also the control function of the switching element of the motor driver. is there.

<Integrated Circuit> In the controller 6 described above, as shown in FIG. 8, the first to third control units 10 and 1 are provided.
1, 12, the converter 17, and the operational amplifier 20 are integrated into a single circuit and are configured as one chip. <Gear Reducer: Canceling Rotational Variation> Next, the gear reducer 4 will be described.

As shown in FIG. 9, the gear reducer 4 includes a reducer input shaft 30 connected to the output shaft of the motor 2 and an output shaft 31 connected to the image carrier 1 of the image forming apparatus. And an intermediate shaft 32. These input shaft 30 and output shaft 31
The intermediate shaft 32 and the intermediate shaft 32 are arranged in parallel with each other, and are rotatably supported by the case 4a of the speed reducer 4. The input gear Z1 is fixed to the input shaft 30, and the input gear Z1 is fixed to the intermediate shaft 32.
The first intermediate gear Z2 meshing with the first intermediate gear Z2 and the second intermediate gear Z3 provided coaxially therewith are fixed, and the output shaft 31
An output gear Z4 that meshes with the second intermediate gear Z3 is fixed to. A flywheel 35 is fixed to the end of the intermediate shaft 32. The number of teeth of each gear is Z1 = 8, Z
It is set to 2 = 80, Z3 = 10, and Z4 = 30.
Here, the number of teeth of the second intermediate gear Z3 used as the input gear of the second reduction stage is 1 / reduction ratio of the first stage,
That is, it is set to "10" sheets. Also, the intermediate shaft 3
The phase (angular position) of the first intermediate gear Z2 and the second intermediate gear Z3, which are mounted on the No. 2, is as described in detail below.
The positional relationship is set so as to cancel out the rotation fluctuation of the motor 2.

First, when the motor 2 rotates, a rotation fluctuation occurs once per one rotation of the motor due to the deviation of the pitch circle center of the motor shaft and the input gear Z1 and the deviation of the parallelism. This fluctuation is transmitted to the intermediate shaft as a rotation fluctuation of 10 times through the meshing between the input gear Z1 (the number of teeth = 8) and the first intermediate gear Z2 (the number of teeth = 80). This rotation fluctuation is almost represented by a sine wave. On the other hand, due to the meshing of the second-stage gears in the speed reducer 4, that is, the meshing of the second intermediate gear Z3 (the number of teeth = 10) and the output gear Z4 (the number of teeth = 30), one rotation of the intermediate shaft 32 occurs. Rotational fluctuation occurs 10 times. This rotation fluctuation is also represented by a sine wave. That is, in the intermediate shaft 32, the rotation fluctuation from the motor 2 and the rotation fluctuation due to the meshing of the second-stage gears Z3 and Z4 occur,
These fluctuations are sinusoidal waves having the same period, although the amplitudes are not equal (it is possible that the amplitudes are almost the same depending on the error of the motor unit etc.). Therefore, if the first intermediate Z2 and the second intermediate gear Z3 are arranged so that their phases (the angular positions of the teeth) deviate by 180 degrees, the phases of the two sine waves described above also deviate by 180 degrees and rotate relative to each other. The fluctuations cancel each other out, and fluctuations in the rotation of the motor 2 can be suppressed.

It should be noted that the intermediate shaft 32 undergoes a relatively high frequency fluctuation due to the meshing of the input gear Z1 and the first intermediate gear Z2, but this fluctuation is absorbed by the flywheel 35. From this, the flywheel 35
Should be provided on the output side of the meshing of the input gear Z1 and the first intermediate gear Z2, that is, on the intermediate shaft 32 or the output shaft 31.

<Rotation Control Operation> Next, the rotation control operation will be described. First, the target value of the output rotation speed of the gear reducer 4 is set in the controller 6. A motor drive signal is generated based on this set value and is given to the motor 2 via the driver 7. As a result, the motor 2 is driven, and the rotation of the motor 2 is decelerated by the gear reducer 4 and transmitted to the image carrier 1 of the image forming apparatus.

At this time, the output rotation speed of the motor 2 is the first
The signal from the first sensor 3 detected by the sensor 3 is given to the first controller 10 of the controller 6. First
The control unit 10 obtains a voltage value or cycle corresponding to a target set value (a target output speed of the gear reducer converted into a motor speed) and a voltage obtained according to a signal from the first sensor 3. Alternatively, the deviation from the signal period is taken. The deviation is given a predetermined gain by the gain circuit 13 and input to the adding / adjusting unit 16.

On the other hand, the output rotation speed of the gear reducer 4 is the second
It is detected by the two sensors 5b and 5c of the sensor 5, and these detection signals are input to the second control unit 11 and the third control unit 12. In the second control unit 11, the voltage value or cycle corresponding to the target setting value (rotation speed of the gear reducer) and the cycle of the voltage or signal obtained according to either one of the two signals from the first sensor 5 The deviation from is taken. The deviation is given a predetermined gain by the gain circuit 14 and input to the addition / adjustment unit 16.

The third controller 12 first detects the average position of the pulse phases obtained from the two sensors 5b and 5c and the phase difference between the pulse phases corresponding to the target set value. The signal generated according to the detection result is given a predetermined gain by the gain circuit 15 and input to the addition / adjustment unit 16. In this way, each control unit 10, 1
A motor drive signal is generated so that the deviations obtained by 1 and 12 become zero, and the motor 2 driven by this motor drive signal causes the output rotation speed of the gear reducer 4 to reach a target value. The rotation speed is controlled.

<Characteristics of First Embodiment> The first feature as described above
The embodiment has the following features. (1) High-precision rotation control can be quickly performed, and the rotation of the motor is stable. As a result, stable control can be performed, generation of unnecessary noise can be suppressed, and the rotation speed of the output shaft can be stabilized.

(2) By using the brushless DC motor, smooth rotation can be obtained in a wide rotation range. (3) Since the rotation speed of the motor is detected by utilizing the magnetic change caused by the rotation of the rotor magnet, a special sensor for detecting the rotation speed of the motor is unnecessary. (4) When the deviation between the sensor detection signal and the set speed value is used as the cycle difference in the second control unit that controls the rotation in response to the detection result of the output rotation speed, the speed deviation is promptly made with one pulse. Can be asked.

(5) In the second control section, when the deviation between the sensor detection signal and the set speed is taken as the frequency difference, the speed deviation which is not affected by temperature drift of the sensor or the like can be digitally obtained. it can. (6) Since the controller 6 controls not only the speed but also the phase, it provides an optimum drive when it is necessary to drive a plurality of image carriers in synchronization in a full-color image forming apparatus or the like. it can.

(7) When detecting the output rotation speed of the reduction gear,
Since the two rotary encoders installed at substantially opposite positions on the output shaft are used, it is possible to cancel a mechanical error around the output shaft of the speed reducer. (8) In the controller 6, since the addition / adjustment of each deviation output is performed by the charge pump circuit, the gain of each deviation output can be individually set by an inexpensive component such as a resistor.

(9) In the gear reducer 4, the arrangement of the pair of gears Z2 and Z3 is arranged so as to cancel out the rotation fluctuation generated for one rotation of the motor, so that the rotation fluctuation of the motor can be suppressed. It is possible to roughly set the requirements for the mechanical accuracy of the motor mounting part. (10) Since the reduction gear 4 is provided with the flywheel, it is possible to reduce speed fluctuation due to meshing of gears of the motor output shaft portion.

(11) Since the circuit forming the control 6 is formed of a one-chip integrated circuit, the control function can be incorporated in the motor board, the motor board can be made smaller, and the cost can be reduced. [Second Embodiment] FIG. 10 shows a second embodiment of the present invention.

The rotary drive device according to the second embodiment is
Only the device and the controller of the first embodiment are different, and other configurations are the same. That is, here, the controller for rotation control is the motor controller 6a.
And an output rotation controller 6b. The detection signal of the first sensor 3 is the motor controller 6
The output signal of the second sensor 5 is input to the output rotation controller 6b.

The specific configuration of the motor controller 6a is the same as that of the first controller 10 in the first embodiment. The specific configuration of the output rotation controller 6b is the same as that of the second and third control units 11 and 12 in the first embodiment. Here, in the output rotation controller 6b, the second and third control units 11 in the first embodiment,
A speed setting signal for the motor is created by the same processing as in 12, and this signal is output to the motor controller 6a.

With the configuration of the second embodiment as described above, it is possible to perform the rotation control with high precision, as in the above. [Third Embodiment] FIG. 11 shows a third embodiment of the present invention. The rotation drive device according to the third embodiment is an example in which a motor speed setting signal from a reduction gear output rotation speed is created in a feedforward manner, and only the device and the controller part of the first and second embodiments are different. The other configurations are the same. In this device, the controller for rotation control includes a motor controller 6a and a phase controller 6c.
The converter 17 is provided in parallel with the phase controller 6c. Further, an adder 18 for adding the output of the phase controller 6c and the output of the converter 17 is provided. The detection signal of the first sensor 3 is input to the motor controller 6a, and the detection signal of the second sensor 5 is input to the phase controller 6c.

The specific configuration of the motor controller 6a is the same as that of the second embodiment, and is the same as that of the first controller 10 in the first embodiment. The specific configuration of the phase controller 6c is the same as that of the third controller 12 in the first embodiment. Further, the converter 17 is similar to the converter 17 in the first embodiment, and converts the target set value of the reduction gear output rotation speed into a set value for the motor speed command.

Here, in the state where the motor rotation speed is maintained by the motor controller 6a, only the phase is controlled by the phase controller 6c by the signal obtained from the output of the reduction gear, and this is added to the target set value. It is given to the motor controller 6a as a motor speed setting signal. With the configuration of the third embodiment as described above, it is possible to perform the rotation control with high accuracy, similarly to the above.

[Fourth Embodiment] FIG. 12 shows a rotation drive device according to a fourth embodiment. In addition to the configuration of the first embodiment, this apparatus is such that another gear speed reducer 40 is connected to the output side of the motor 2 and the output of the gear speed reducer 40 is used for driving a developing machine or a cleaner of the image forming apparatus. Used as. The image carrier 1 of the image forming apparatus requires highly accurate rotation control, but does not require rotational accuracy for the developing machine and the cleaner. Therefore, in the device of the second embodiment,
Configuration similar to the first embodiment (first and second sensors 3, 5,
The image carrier is driven by the controller 6 and the driver 7), and the developing machine and the like are driven by another drive system including the gear speed reducer 40 and not performing any rotation control.

Here, one motor 2 can be used to configure a first drive system that performs highly accurate rotation control and a second drive system that does not perform rotation control. Therefore, it is possible to realize a device that is inexpensive and effective in terms of space utility. [Other Embodiments] (a) In the above embodiment, the brushless DC is used as the motor.
I used a motor, but like a stepping motor,
A motor having a speed maintaining function may be used as the motor unit. In this case, the first sensor 3 and the first controller 10 of the controller 6 in the above embodiment can be omitted.

(B) In the above embodiment, the controller 6
Alternatively, although the output rotation controller 6b is provided with the third control unit for performing the phase control, this third control unit is not always necessary and may be omitted in some cases. (C) In the above embodiment, the two sensors 5b and 5c are provided in order to detect the output rotation speed of the speed reducer, but only one sensor may be provided and the other one may be omitted.

(D) As shown in FIG. 13, the flywheel may be mounted on the shaft whose speed is increased. Here, a speed increasing shaft 45 is provided parallel to the output shaft of the gear reducer 4, a large pulley 50 is fixed to the output shaft end of the gear speed reducing 4, a small pulley 51 is fixed to the speed increasing shaft 45, A belt 52 is stretched between the pulleys 50 and 51. That is, the speed increasing shaft 45 is accelerated more than the rotation of the output shaft.
The flywheel 53 is fixed to the end of the speed increasing shaft 45.

In such a structure, since the flywheel 53 is mounted on the shaft whose rotational speed is increased, the same effect can be obtained with a flywheel having a smaller size than when mounted on the output shaft. To be

[0075]

As described above, according to the present invention, inexpensive and highly accurate rotation speed control can be performed. Further, a rotation drive device in which vibration is further suppressed can be obtained. Further, the motor substrate can be miniaturized by forming an integrated circuit.

[Brief description of drawings]

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

FIG. 2 is a block diagram of a controller of the device.

FIG. 3 is a configuration diagram of a first control unit of the controller.

FIG. 4 is a diagram showing a specific configuration of a second sensor of the device.

FIG. 5 is a diagram for explaining the operation of the second sensor.

FIG. 6 is a diagram for explaining the operation of the second sensor.

FIG. 7 is a circuit diagram of an addition / adjustment unit of the controller.

FIG. 8 is an integrated circuit diagram of the controller.

FIG. 9 is a schematic diagram of a gear reducer of the device.

FIG. 10 is a block diagram of a rotary drive device according to a second embodiment of the present invention.

FIG. 11 is a block diagram of a rotary drive device according to a third embodiment of the present invention.

FIG. 12 is a block diagram of a rotary drive device according to a fourth embodiment of the present invention.

FIG. 13 is a diagram showing another embodiment of a gear reducer.

[Explanation of symbols]

1 Image carrier 2 motor 3 First sensor 4,40 gear reducer 5 Second sensor 6 controller 10 First control unit 11 Second control unit 12 Third control unit 13, 14, 15 gain 16 Addition / adjustment section

Claims (20)

[Claims] 1. A rotation drive device for driving a driven body at a set rotation speed, comprising a motor as a rotation drive source, and a motor rotation speed detection means for detecting an output rotation speed of the motor. A speed reducer for decelerating the output shaft rotation of the motor, an output rotation speed detecting means for detecting the rotation speed of the output shaft of the speed reducer, and signals from the motor rotation speed detecting means and the output rotation speed detecting means. And a controller that controls the motor rotation speed so that the rotation speed of the reduction gear output shaft reaches a set speed. 2. The motor includes a DC including a brassless type motor.
The rotary drive device according to claim 1, which is a motor. 3. The controller receives a signal from the motor rotation speed detecting means and controls the motor rotation speed, and a controller receives the signal from the output rotation speed detecting means. And a second control section for controlling the motor, the motor, the motor rotation speed detecting means, and the first control section are unitized to be configured as a motor unit having a speed maintaining function independently. The rotary drive device according to. 4. The motor rotation speed detecting means has a first sensor for detecting a magnetic change caused by rotation of a rotor magnet of the motor, and the first control section outputs the output signal of the first sensor to the speed reducer. The rotation drive device according to claim 3, wherein the motor is controlled so that there is no deviation with respect to the rotation speed of the motor corresponding to the set speed of the output. 5. The second output rotation speed detecting means outputs a frequency signal proportional to the rotation speed of the output shaft of the speed reducer.
The rotary drive according to claim 4, further comprising a sensor, wherein the second control unit controls the motor such that an output signal of the second sensor has a smaller deviation from a set speed of the speed reducer output. apparatus. 6. The rotary drive device according to claim 5, wherein the deviation between the output signal of the second sensor and the set speed in the second controller is a difference in cycle. 7. The rotary drive device according to claim 5, wherein the deviation between the output signal of the second sensor and the set speed in the second controller is a frequency difference. 8. The third controller, in addition to the first controller and the second controller, operates so as to reduce a phase difference between a signal indicating a set speed and the second sensor output frequency signal. The rotary drive device according to claim 6, further comprising a portion. 9. The output rotation speed detecting means includes the second sensor, and is installed at a position substantially equal to N in a circumferential direction around the output shaft of the speed reducer (N is 2 or more). Number of sensors), and the third control unit cancels a mechanical error of the detected reduction gear output rotation speed around the reduction gear output shaft based on the signals of the N sensors. The rotary drive device according to claim 8. 10. The N sensors are two rotary encoders installed at positions substantially opposite to each other on an output shaft that outputs a pulse signal, and the third control unit includes a rotary encoder for the two rotary encoders. The rotation drive device according to claim 9, wherein a mechanical error around the output shaft of the reduction gear is canceled based on a temporal overlap of output signal pulses. 11. The controller includes deviation output means for realizing the first control section and the second control section, or the first control section, the second control section, and the third control section, respectively, One addition for adjusting the output of the deviation output means by taking into consideration a predetermined gain for each
11. The rotary drive device according to claim 8, further comprising an adjusting unit, which outputs a signal for controlling the rotation speed of the motor by the adding / adjusting unit. 12. The rotary drive device according to claim 11, wherein the controller has a charge pump circuit for performing addition and adjustment of outputs of the respective deviation output means. 13. The speed reducer has at least one set of gears, and the gears mesh with each other once for one rotation of the motor.
13. The rotary drive device according to claim 1, wherein the rotary drive device is set to have a phase relationship that cancels the rotational fluctuation that occurs in a cycle. 14. The rotary drive device according to claim 1, wherein the speed reducer includes a flywheel for suppressing fluctuations in rotation of the output shaft of the speed reducer. 15. The rotary drive device according to claim 14, wherein the reduction gear has a reduction mechanism of two or more stages having an intermediate shaft, and the flywheel is installed on the intermediate shaft. 16. The rotary drive device according to claim 1, wherein the driven body is an image carrier of an image forming apparatus. 17. A second motor, which is provided separately from the output shaft of the speed reducer and is connected to the motor, and whose rotational speed is not controlled.
The rotary drive device according to claim 1, further comprising an output shaft. 18. The output shaft of the speed reducer drives an image carrier of the image forming apparatus, and the second output shaft drives a driven body other than the image carrier of the image forming apparatus. The rotary drive device according to. 19. A motor as a rotary drive source, a motor rotational speed detecting means for detecting an output rotational speed of the motor, a speed reducer for decelerating an output shaft rotation of the motor, and an output shaft of the speed reducer. Output rotation speed detection means for detecting the rotation speed of the motor, and the motor rotation so that the rotation speed of the speed reducer output shaft reaches a set speed by receiving signals from the motor rotation speed detection means and the output rotation speed detection means. An integrated circuit used for a rotation drive device that drives a rotation of a driven body at a predetermined set speed, the controller including a controller for controlling a speed, wherein the controller is a signal from the motor rotation speed detection means and the setting. A first deviation output section that takes a deviation from the rotation speed of the motor corresponding to the speed, and a second deviation output section that takes a deviation between the signal from the output rotation speed detection means and the set speed. Section and an adder / adjuster for adding and adjusting the output signals from the first and second deviation output sections in consideration of a predetermined gain, and the deviation output section and the addition / adjustment section are integrated in one chip. An integrated circuit for a rotation driving device, which is composed of a circuit. 20. The controller comprises the first and second
In addition to the deviation output section, a third deviation output section for obtaining a phase difference between a signal representing the set rotation speed and a signal from the output rotation speed detection means is further provided, and the third deviation output section includes the first deviation output section. 20. The integrated circuit for a rotation drive device according to claim 19, wherein the integrated circuit for a rotary drive is configured with the second deviation output section and the addition / adjustment section.