JP2003009564A - Motor controller and image forming apparatus using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To allow a precision control of the speed of a motor by suppressing a rotational change of the motor due to a torque change caused by the position of the motor irrespective of a control period of the motor. SOLUTION: A motor controller comprises a periodic control signal output unit 110 for controlling the motor 100 at a constant speed, and a positional control signal output unit 112 for outputting a control signal in response to the position of the motor, Thus, the rotational change of the motor due to the torque change caused by the position of the motor is suppressed, and a precision speed control can be easily performed. Further, an image forming position for forming an image of a high quality level can be realized in small size and light weight.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention reduces rotational fluctuations due to torque fluctuations due to motor position such as motor cogging and torque ripple components, and enables accurate speed control. The present invention relates to a motor control device that controls a motor or the like that drives a body and an image forming apparatus that uses the device.

[0002]

2. Description of the Related Art A motor speed control device that detects a motor speed and follows a speed command value is widely used as a motor for driving a photoconductor in an electrophotographic process. Since this control device performs feedback control such as known PI control on the speed detected by the motor, it is impossible to sufficiently suppress the rotation fluctuation due to the torque fluctuation such as the motor cogging or the torque ripple component. .

An example of the structure for controlling the speed of a motor for driving a photosensitive member in a conventional electrophotographic process will be described with reference to the drawings.

FIG. 16 is an explanatory diagram showing the structure of a conventional image forming apparatus.

In the electrophotographic process, on the photoconductor 906,
A toner image is formed by the exposing means, charging means, and developing means, and is transferred onto paper to form an image. Therefore, in order to realize a high-quality image, highly accurate speed control of the photoconductor is essential. is there. Therefore, the motor 900 that drives the photosensitive member 906 of the conventional electrophotographic process is rotated at a relatively high speed, decelerated by the gear 902, and then a large inertial load 904 is attached to the load side, and the rotational fluctuation is sufficiently reduced by this inertial load. It was configured to do.

Further, as a conventional example for suppressing periodical rotation fluctuation due to motor cogging or torque ripple component, a signal having a period corresponding to the rotation speed of the motor is disclosed in, for example, Japanese Patent Laid-Open No. 62-89487. The rotation detector generated and the interval between the signals generated by this rotation detector are counted by the clock pulse of the oscillation circuit to obtain a speed signal that is inversely proportional to the rotation speed, and the rotation error obtained from this speed signal is calculated and combined. Then, a configuration for updating and storing the control signal stored in the memory for suppressing the rotation error is invented.

With these configurations, it was possible to suppress fluctuations in rotation due to cogging of the motor, torque ripple components, etc., and realize accurate speed control.

[0008]

However, in the conventional method of mounting the inertial load to suppress the rotational fluctuation, a relatively large inertial load has to be mounted, and in order to reduce the size of the entire electrophotographic process. It had the problem of becoming an obstacle. Also, in order to reduce the size, when a motor is directly attached to the photoconductor, a motor with a large output torque is required in order to prevent gear reduction, and as the output torque increases, cogging and torque ripple components of the motor increase, There was also a problem that the rotation fluctuation became worse.

Further, in the conventional method in which the speed control is performed by measuring the interval between the signals generated by the rotation detector, the interval at which the speed signal is obtained changes when the rotation speed of the motor changes.
The control interval fluctuates. As a result, not only is it necessary to change the control gain according to the rotation speed of the motor, but the control interval is determined by the rotation speed of the motor and the rotation detector, which makes it difficult to set the responsiveness of speed control arbitrarily. Had a point.

[0010]

In order to solve the above problems, a motor control device according to the present invention includes a motor, a position detector that outputs a position signal according to the position of the motor, and a position detector for the position detector. In a motor control device having speed detection means for outputting the rotation speed of the motor from the output, and speed control means for controlling the rotation speed of the motor to a predetermined speed command value according to the output of the speed detection means, The speed control means outputs a control signal A so that the output of the speed detection means follows the speed command value for each control cycle, and a control signal according to the position of the position detector. A position control signal output means for outputting B, a control signal A of the cycle control signal output means and a control signal B of the position control signal output means are added to obtain a control signal for the motor. .

Further, in the image forming apparatus of the present invention, a photoconductor, a motor attached to the photoconductor, a position detector for outputting a position signal according to the position of the motor, and an output of the position detector. In the electrophotographic process having speed detection means for outputting the rotation speed of the motor, and speed control means for controlling the rotation speed of the motor to a predetermined speed command value according to the output of the speed detection means. The speed control means outputs a control signal A so that the output of the speed detection means follows the speed command value for each control cycle, and a control signal B corresponding to the position of the position detector. And a control signal A of the cycle control signal output means and a control signal B of the position control signal output means are added to form a control signal of the motor. That.

[0012]

BEST MODE FOR CARRYING OUT THE INVENTION A motor controller according to an embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 is an overall view showing the configuration of a motor control device according to a first embodiment of the present invention.

In FIG. 1, 100 is a motor, 102 is a position detector, 104 is a current controller, 106 is a position signal processor, 108 is a differentiator, 110 is a cycle control signal output device,
112 is a position control signal output device, and 114 is an adder.

FIG. 2 is a conceptual diagram of the position detector 102.

FIG. 3 is an explanatory diagram showing an example of the position signal output from the position detector 102.

FIG. 4 is an explanatory diagram showing an example of the velocity error waveform.

The operation of the motor control device configured as described above will be described below with reference to FIGS. 1, 2, 3, and 4.

A position detector 102 for detecting the position of the motor is attached to the motor 100. Position detector 10
2, the MR element detects the magnetization pattern of a magnet that is magnetized in advance, and outputs signals MR1 and MR2 whose phases are 90 degrees as shown in FIG. These MR1 and MR2 signals are input to the position signal processor 106 to detect the position of the motor. This position signal processor 10
The operation of 6 may be obtained by calculating an inverse trigonometric function from the instantaneous signals of MR1 and MR2 at any time. further,
This position signal is converted into a motor speed by the differentiator 108.

Next, the speed control operation of the present invention will be described in detail.

The period control signal output device 110 is a well-known PI control represented by, for example, (Equation 1) so that the detected speed ωm follows the speed command value ωd in every predetermined control cycle. It is sufficient to control the torque command τa as a control signal.

[0022]

[Equation 1]

Here, Kis and Kps are feedback gains. In the case of this control method, the control cycle does not depend on the position detector or the motor speed, and may be set freely to ensure arbitrary responsiveness. Generally, the response is improved by shortening the control cycle.

Next, a conventionally known period control signal output device 1
When the speed control is performed with only the torque command of 10, the control is delayed because the speed is detected and the feedback control is performed, and the speed error ωe between the speed command value ωd and the motor detected speed ωm, ωe = ωd−ωm … (Equation 2) is due to the effects of motor cogging and torque ripple components.
The rotation fluctuation waveform varies with the motor position as shown in FIG. In particular, in a system in which the load and the motor are directly connected without a decelerator, it is necessary not only to rotate the motor at a low speed, but also to increase the torque generated by the motor, which causes cogging and torque of the motor. The influence of the ripple component becomes large.

Therefore, the position control signal output device 112 measures in advance the torque command τb for correcting the torque fluctuation component determined by the position of the motor, such as the cogging of the motor and the torque ripple component, and processed by the position signal processor 106. Output according to the motor position.

At this time, if the torque command τb for correcting the torque fluctuation component is output as a time function corresponding to the time, even if the speed is controlled to a constant value, the control cycle is adjusted to match the phase of the correction torque. The rotation speed must be set in consideration, and the phase of the correction torque is deviated due to the influence of the speed fluctuation, so that the rotation fluctuation cannot be sufficiently suppressed.

The torque command τa of the cycle control signal output device 110 and the torque command τb of the position control signal output device 112 described above.
Is added by the adder 114 to obtain a torque command. And
The current control unit 104 controls the current supplied to the motor 100 by known PI control or the like so as to generate the commanded torque.

With the above configuration, it is possible to suppress rotation fluctuation due to cogging and torque ripple components of the motor regardless of the control cycle of the motor, and it is possible to realize accurate speed control.

In this embodiment, the differentiator is used to detect the speed from the position of the motor, but it is also possible to use a differentiator or the like that can be processed by a digital signal.

Further, in this embodiment, the PD shown in (Equation 1) is used.
Although the example of the speed control of the control has been described, as is apparent from the configuration of the embodiment, the same effect can be obtained by other control methods such as PID control including position control.

Further, in this embodiment, the torque control is facilitated by performing the current control, but the control may be performed by a known voltage drive which does not have the current control.

Next, in the first embodiment, the torque command τb for correcting the torque fluctuation component determined by the position of the motor, such as the cogging of the motor and the torque ripple component, needs to be checked in advance by some method, and the speed command value If the load changes and the motor cogging or torque ripple component changes, there is a problem that setting is not easy.

Therefore, as a second embodiment of the present invention, there is provided a motor control device capable of automatically updating the optimum correction torque without adjusting the correction torque in advance.

A motor controller according to a second embodiment of the present invention will be described below with reference to the drawings.

FIG. 5 is an overall view showing the configuration of the motor control device in the second embodiment of the present invention.

In FIG. 5, 100 is a motor, 102 is a position detector, 104 is a current controller, 106 is a position signal processor, 108 is a differentiator, 110 is a period control signal output device,
114 is an adder, 200 is a storage means, 202 is a correction value calculation means, and 204 is an adder.

The operation of the motor control device configured as described above will be described below with reference to FIG.

Similar to the motor control device of the first embodiment,
Position detector 10 for detecting the position of the motor 100
2 is attached, the position of the motor is detected by the position signal processor 106, and further converted into the speed of the motor by the differentiator 108. Then, the cycle control signal output device 11
0 outputs the torque command τa such that the detected speed follows the speed command value at each predetermined control cycle.

Next, the operation of outputting the position control signal of the present invention will be described in detail.

As described in the first embodiment, when the speed is controlled by the torque command of only the cycle control signal output unit 110, the motor position as shown in FIG. 4 is affected by the cogging of the motor and the torque ripple component. The waveform of the rotational fluctuation fluctuates with. Therefore, the correction value calculation means 202 sets the correction signal τc as a value obtained by multiplying the correction gain Kc by a velocity error such as τc = Kc · (ωd−ωm) (Equation 3).

The storage means 200 stores the motor position θm.
The torque command τb_mem for correcting the fluctuation component according to
[Θm] is stored, and the torque command τb_mem [θm] stored in the storage unit 200 is stored by the adder 204.
And a correction signal τc calculated by the correction value calculation means 202 are added to obtain a torque command τb for correcting a torque fluctuation component such as τb [θm] = τb_mem [θm] + τc (Equation 4).
Output [θm]. Further, the torque command τb [θm] corrected by the adder 204 is updated to τb_mem [θm] = τb [θm] (Equation 5) and stored in the storage unit 200.

Here, since the storage means only needs to store the torque command corresponding to the position of the motor, it is not necessary to store a value more than one revolution of the motor. Further, when the torque fluctuation component has a plurality of cycles per one rotation of the motor depending on the number of stations and the number of slots of the motor, it is possible to reduce the storage capacity according to the cycle.

Then, as in the first embodiment, the torque command τa of the cycle control signal output device 110 and the torque command τb of the position control signal are added by the adder 114 to obtain a torque command,
The current controller 104 controls the current supplied to the motor 100 so as to generate the commanded torque.

With the above configuration, it is not necessary to adjust the torque fluctuation component determined by the motor position such as the motor cogging or torque ripple component in advance by any method, and the speed command value or the load is changed to change the motor cogging or torque. Even when the ripple component or the like changes, it is possible to suppress the rotation fluctuation due to the cogging of the motor or the torque ripple component regardless of the control cycle of the motor, and it is possible to easily realize accurate speed control.

In the present embodiment, the correction signal τc is obtained by multiplying the speed error by the correction gain. However, not only the speed error but also the position error signal may be used together. Therefore, the torque command τa output from the cycle control signal output device 110 may be used.

Next, in the second embodiment, it is possible to suppress the rotational fluctuation due to the torque fluctuation component determined by the position of the motor such as the cogging of the motor and the torque ripple component by using the speed signal according to the position of the motor. However, when the storage capacity of the storage unit that stores the resolution of the position detector that detects the position of the motor and the correction signal according to the motor position is small, especially when the torque command that suppresses the rotation fluctuation is being updated. In this case, the value of the position detector may not change for each control cycle, and there are problems such as correction positions that are updated and saved multiple times at once, and it takes time to achieve the desired characteristics. Was.

Therefore, as a third embodiment of the present invention, it is possible to automatically update the optimum correction torque even when the output of the position detector for detecting the position of the motor does not change in each control cycle. Provided is a motor control device.

A motor controller according to the third embodiment of the present invention will be described below with reference to the drawings.

FIG. 6 is an overall view showing the configuration of a motor control device according to the third embodiment of the present invention.

In FIG. 6, 100 is a motor, 102 is a position detector, 104 is a current controller, 106 is a position signal processor, 108 is a differentiator, 110 is a cycle control signal output device,
114 is an adder, 200 is a storage unit, 202 is a correction value calculation unit, 204 is an adder, and 210 is an averaging unit.

The operation of the motor control device configured as described above will be described below with reference to FIG.

Similar to the motor control device of the first embodiment,
Position detector 10 for detecting the position of the motor 100
2 is attached, the position of the motor is detected by the position signal processor 106, and the speed of the motor is converted by the differentiator 108. Then, the cycle control signal output device 110 outputs the torque command τa such that the detected speed follows the speed command value for each predetermined control cycle.

The memory means 200 stores a torque command τb_mem [θ for correcting the fluctuation component according to the motor position θm.
m] is stored. In the second embodiment, this torque command is updated and saved by the correction signal calculated by the correction value calculation means 202, but due to factors such as the resolution of the position signal, the position detector at a certain control time A. In some cases, the position signal of and the position signal in the control cycle before that do not change.

In this case, the torque command τb is continuously output a plurality of times.
Since _mem [θm] is updated, the balance with other motor positions becomes poor.

Therefore, the averaging means 210 stores the number of times the position signal of the position detector does not change, and the total sum of the correction signals at that time is calculated and averaged.

For example, the position signal at a certain control time t is θ
Let m be the correction signal τc (t) at that time. The position signal at the next control time t + Δt is also the same θm, and is set as the correction signal τc (t + Δt) at that time. At this time, the correction signal τc_ave at the motor position θm is τc_ave = {τc (t) + τc (t + Δt)} / 2 (Equation 6). Then, the average value τc_ave of the correction signal is calculated by the adder 204 as τb [θm] = τb_mem [θm] + τc_ave (Equation 7) and the torque command τb_me stored in the storage unit 200.
The torque command τb [θm] for correcting the torque fluctuation component may be updated and output by adding it to m [θm], and may be stored in the storage unit 200 again as in the second embodiment.

Here again, the storage means only needs to store the torque command corresponding to the position of the motor, so that it is not necessary to store more than one rotation of the motor. In addition, the torque fluctuation component depends on the number of motor stations and the number of slots of the motor 1.
When the rotation has a plurality of cycles, the storage capacity can be reduced according to the cycles. Further, by using the averaging process of this embodiment, it is possible to reduce the resolution of the motor position and reduce the storage capacity when the position control signal corresponding to the position of the motor is generated.

Then, as in the first embodiment, the torque command τa of the cycle control signal output device 110 and the torque command τb of the position control signal are added by the adder 114 to obtain a torque command,
The current controller 104 controls the current supplied to the motor 100 so as to generate the commanded torque.

With the above configuration, the torque fluctuation component determined by the motor position such as the motor cogging or torque ripple component is automatically detected even if the output of the position detector for detecting the motor position does not change in each control cycle. It is possible to update the optimum correction torque, and it is possible to easily realize accurate speed control.

Next, in the second and third embodiments, it has been described that the speed fluctuation can be used to suppress the rotation fluctuation due to the torque fluctuation component determined by the motor position such as the motor cogging or the torque ripple component. However, there is a problem that desired characteristics cannot be obtained when the detected speed has noise.

Therefore, as a fourth embodiment of the present invention, even when noise is present in the speed signal, rotation due to a torque fluctuation component determined by the position of the motor, such as cogging or torque ripple component of the motor using the speed signal. Provided is a motor control device capable of suppressing fluctuation.

A motor controller according to a fourth embodiment of the present invention will be described below with reference to the drawings.

FIG. 7 is an overall view showing the configuration of a motor control device according to the fourth embodiment of the present invention.

In FIG. 7, 100 is a motor, 102 is a position detector, 104 is a current controller, 106 is a position signal processor, 108 is a differentiator, 110 is a cycle control signal output device,
114 is an adder, 202 is a correction value calculation means, 204 is an adder, 300 is a storage means, 302 is a filter, 304
Is a position signal corrector.

FIG. 8 is an explanatory diagram showing an example of the speed error waveform before the rotation fluctuation correction and the speed error waveform after the filtering.

FIG. 9 is an explanatory diagram showing an example of the frequency analysis waveform of the speed error before the rotation fluctuation correction.

FIG. 10 is an explanatory diagram showing the operations of the filter 302 and the position signal corrector 304.

FIG. 11 is an explanatory diagram showing an example of the speed error waveform after the rotation fluctuation correction and the speed error waveform after the filtering.

FIG. 12 is an explanatory diagram showing an example of the frequency analysis waveform of the speed error after the rotation fluctuation correction.

The operation of the motor control device configured as described above will be described below with reference to FIGS. 7, 8, 9, 10, 11, and 12.

Similar to the motor control devices of the first and second embodiments, the motor 100 is provided with the position detector 102 for detecting the position of the motor, and the position signal processor 106.
The position of the motor is detected by and is further converted into the speed of the motor by the differentiator 108. Then, the cycle control signal output device 110 outputs the torque command τa such that the detected speed follows the speed command value for each predetermined control cycle.

Next, the operation of outputting the position control signal of the present invention will be described in detail.

As described in the first and second embodiments, when the speed is controlled by the torque command of only the cycle control signal output device 110, the motor speed waveform is affected by the cogging of the motor and the torque ripple component. Is a rotation fluctuation waveform that changes depending on the motor position. Therefore, in the second embodiment, the correction is made by multiplying the speed error by the correction gain.

However, there is noise in the detected speed of the motor or the position signal M processed by the position signal processor 106.
When the signals of R1 and MR2 deviate from the ideal sine wave, the absolute accuracy of the motor position after signal processing deviates,
A large noise may be contained in the velocity signal obtained by differentiating the motor position. An example of the actually measured speed error is shown in FIG. The upper waveform in FIG. 8 is the velocity error waveform. Even if an attempt is made to suppress the rotation fluctuation with such a signal, a sufficient suppression effect may not be exhibited in some cases.

In order to remove the influence of this noise, a filter 30 for removing the high frequency noise of this velocity error waveform.
Introduce 2. The waveform at the bottom of FIG. 8 is the waveform of the speed error after passing through the filter 302, and fluctuations due to the position of the motor such as cogging of the motor and torque ripple components can be easily detected. Further, FIG. 9 shows a waveform obtained by frequency-analyzing the speed waveform obtained by detecting the motor speed with the external measuring device at this time.
As can be seen from FIG. 9, the torque ripple component of the motor is large.

On the other hand, when a filter is passed through to remove high frequency noise, the phase is delayed due to the influence of the filter as shown in the upper and middle figures of FIG. Therefore, if you try to suppress the rotational fluctuation with the waveform after filtering, you cannot suppress the rotational fluctuation sufficiently because the phase shifts,
Depending on the motor speed and the configuration of the filter, the phase may be inverted and unstable.

Therefore, the present invention has a correction means for correcting the phase delay as shown in the lower diagram of FIG. This operation will be described below.

In general, since the time delay due to the filter is uniquely determined by the configuration of the filter, how much time should be advanced from the velocity error waveform after filtering,
When rotating at a constant speed, how fast the phase is,
That is, it is easy to know whether to move the motor position forward.
However, estimating a current signal from a signal delayed in time is equivalent to estimating a future signal from a current signal, and is not easy.

However, as in the second embodiment, it is possible to store the torque command τb_mem [θm] for correcting the fluctuation component in the storage means 300 according to the motor position θm. When the speed is controlled at a constant speed as shown by, the position signal corrector 304 causes the filter 302 to lag behind the current position θm by the position θf.
The previous position is corrected to the position of θc = θm−θf (Equation 8). Then, the torque command τb_mem [θc] for this position θc is corrected by the adder 204 by correcting the correction signal τc calculated by the correction value calculating means 202 similar to that of the second embodiment with the high-frequency component removed by the filter 302. A torque command τb that is added to the signal τf to correct the torque fluctuation component, such as τb [θc] = τb_mem [θc] + τf (Equation 9).
[Θc] is calculated and updated to τb_mem [θc] = τb [θc] (Equation 10) and stored in the storage unit 300.

On the other hand, the correction signal from the storage means 300 is
By outputting the torque command τb [θm] of the current motor position θm, it is possible to suppress the torque fluctuation component according to the motor position without delay by the filter.

Then, as in the first embodiment, the torque command τa of the cycle control signal output device 110 and the torque command τb corresponding to the current motor position are added by the adder 114 to obtain a torque command, and the current controller 104 is used. Then, the current supplied to the motor 100 is controlled so as to generate the commanded torque.

FIG. 11 shows an example of the actually measured speed error when the torque fluctuation component is suppressed according to the present embodiment.
The upper waveform in FIG. 11 is the velocity error waveform, and the lower waveform in FIG. 11 is the velocity error waveform after passing through the filter 302. It can be seen that the fluctuations due to the position of the motor such as the cogging of the motor and the torque ripple component, which are seen in FIG. 8, are reduced. Further, FIG. 12 shows a waveform obtained by frequency-analyzing the speed waveform in which the motor speed is detected by the external measuring device at this time, and it can be seen that the torque ripple component of the motor is significantly reduced.

With the above configuration, the rotation fluctuation due to the cogging of the motor and the torque ripple component can be suppressed irrespective of the control cycle of the motor, and even when the detected speed has noise. Good speed control can be realized.

Here again, since the storage means only needs to store the torque command corresponding to the position of the motor, it is not necessary to store more than one rotation of the motor. In addition, the torque fluctuation component depends on the number of motor stations and the number of slots of the motor 1.
When the rotation has a plurality of cycles, the storage capacity can be reduced according to the cycles.

If the filter for removing the high frequency component is a linear phase filter having a linear phase characteristic, the phase delay amount by the filter can be easily calculated.

The filter for removing the high frequency component may be an average value calculating means for calculating an average value for a predetermined average number of times. In that case, the phase delay amount by the filter corresponds to half the average number. The amount of movement of the motor in time may be set as the amount of phase delay.

Further, the filter for removing the high frequency component is the component of the position detector 102, that is, M in this embodiment.
A filter for removing the components of R1 and MR2 may be used.

Next, the above-described embodiments relate to the motor control device capable of suppressing the rotational fluctuation due to the cogging of the motor and the torque ripple component regardless of the control cycle of the motor and realizing the speed control with high accuracy. Although the description has been given, an embodiment in which the motor control device is used to drive the photoconductor in the electrophotographic process will be described below.

As a fifth embodiment of the present invention, even when the motor is directly attached to the photosensitive member to reduce the size, it is possible to suppress the rotational fluctuation due to the cogging of the motor and the torque ripple component, and to reduce the rotational speed of the photosensitive member. An image forming apparatus that can be controlled with high accuracy.

An image forming apparatus according to the fifth embodiment of the present invention will be described below with reference to the drawings.

FIG. 13 is an overall view showing the structure of the image forming apparatus in the fifth embodiment of the present invention.

In FIG. 13, 500 is a motor, 502
Is a position detector, 504 is a photoconductor, and 506 is a motor controller.

The operation of the image forming apparatus configured as described above will be described below with reference to FIG.

Unlike the conventional image forming apparatus shown in FIG. 16,
The photoconductor 504 is directly attached to the motor 500 without using a speed reducer. In the electrophotographic process, the photoconductor 50
A toner image is formed on the surface 4 by a known exposing means, charging means, and developing means, and is transferred to paper or the like to form an image. Therefore, in order to realize a high quality image, it is necessary to control the speed of the photoconductor with high accuracy. Moreover, since the motor must rotate at a low speed by not using the decelerator, it is necessary to increase the torque of the motor itself, so that the cogging and the torque ripple component of the motor become large.
In feedback control such as I control, speed control with desired accuracy is difficult.

Therefore, the motor controller 506 causes the motor 5
The position information of the position detector 502 for detecting the position of the motor 500 attached to
Alternatively, by using the motor control device of the third or fourth embodiment, it is possible to suppress rotation fluctuations due to torque fluctuations such as motor cogging and torque ripple components, and accurate speed control is possible. As a result, it is possible to control the speed of the photoconductor with high accuracy and form a high-quality image.

With the above construction, even if the motor is directly attached to the photoconductor, a high-quality image can be formed, and a speed reducer and an inertial load are not required, so that the electrophotographic process can be easily downsized. .

Next, the fifth embodiment is effective when the motor load is constant, but when a cleaning blade for cleaning the toner remaining on the photoconductor is pressed against the photoconductor, The load torque changes significantly. As a result, the torque ripple component changes, and there is a problem that the speed accuracy of the photoconductor is temporarily deteriorated until the torque command for correcting the rotational fluctuation of the photoconductor is updated and stored.

Therefore, as a sixth embodiment of the present invention, there is provided an image forming apparatus capable of accurately controlling the speed of the photoconductor even when the cleaning blade is pressed against the photoconductor.

An image forming apparatus according to the sixth embodiment of the present invention will be described below with reference to the drawings.

FIG. 14 is an overall view showing the structure of the image forming apparatus in the sixth embodiment of the present invention.

In FIG. 14, 500 is a motor, 502
Is a position detector, 504 is a photoconductor, 600 is a motor controller, 602 is a cleaning blade, 604 is a cleaning blade driver, and 606 is a cleaning blade commander.

FIG. 15 is an explanatory diagram showing the structure of a motor controller 600 according to the sixth embodiment of the present invention.

In FIG. 15, 104 is a current controller and 1 is a current controller.
06 is a position signal processor, 108 is a differentiator, 110 is a cycle control signal output device, 114 is an adder, 202 is a correction value calculating means, 204 is an adder, 600 is a motor controller, 606
Is a cleaning blade commander, 610 is a normal storage means, 612 is a cleaning storage means, 614, 616
Is a switch.

The operation of the image forming apparatus configured as described above will be described below with reference to FIGS. 14 and 15.

Similar to the image forming apparatus of the fifth embodiment, the photosensitive member 504 is directly attached to the motor 500 without a speed reducer, and the position detection for detecting the position of the motor 500 attached to the motor 500 is performed. The motor controller 600 controls the motor 500 using the position information of the device 502.

In this embodiment, the cleaning blade 602 for cleaning the photoconductor 504 is provided, and when the cleaning blade command unit 606 issues a command for cleaning the photoconductor, the cleaning blade drive unit 604 exposes the cleaning blade 602 to the photoconductor. The toner or the like remaining on the photoconductor is cleaned by pressing it against the body 504.

Next, the operation of the motor controller 600 will be described in detail.

Similar to the motor control device of the second embodiment,
The position signal processor 106 detects the position of the motor from the signal from the position detector 502 attached to the motor 500, and is further converted into the speed of the motor by the differentiator 108.
Then, the cycle control signal output device 110 outputs the torque command τa such that the detected speed follows the speed command value for each predetermined control cycle.

As described in the first embodiment, when the speed is controlled by the torque command of only the cycle control signal output unit 110, the rotation fluctuation fluctuates depending on the motor position due to the influence of the motor cogging and the torque ripple component. Grows larger. Therefore, similarly to the second embodiment, the torque command for correcting the fluctuation component stored in the storage unit according to the position θm of the motor is corrected by the adder 204 with the correction signal τc from the correction value calculation unit 202. Add, save and update.

Here, when the cleaning blade 602 is pressed against the photoconductor 504, the load torque of the motor for driving the photoconductor increases, and the torque ripple component also increases accordingly. However, although the update storage operation by the correction value calculation unit 202 can automatically suppress the rotation fluctuation due to the torque fluctuation component such as the torque ripple component determined by the position of the motor, the rotation fluctuation is suppressed until the update storage operation is completed. It cannot be suppressed enough.

Therefore, in the present invention, the normal time storage means 61
0 and a memory unit 612 for cleaning, and the switching unit 614, 616 stores the memory unit for normal time in the normal time when the cleaning blade is not pressed against the photoconductor by the command of the cleaning blade command unit 606. At the time of cleaning by connecting the cleaning blade to the photoconductor, the switching devices 614 and 61 are connected.
6 is connected to the cleaning time storage means 612. As a result, it becomes possible to output a torque command for correcting the cleaning blade separately depending on whether or not the cleaning blade is pressed against the photoconductor, and it is possible to separately perform the update / save operation by the correction value calculating means 202.

With the above arrangement, even if the cleaning blade is pressed against the photosensitive member and the torque ripple fluctuates, it is possible to instantaneously suppress the rotational fluctuation and always form a high-quality image. Become.

Although the storage means is described as two in this case, it may be increased if necessary, such as when there are a plurality of speed settings for the photoconductor.

Further, in order to form a high-quality image from the first image formation immediately after power-on in the electrophotographic process, a test operation is performed in which only the motor is driven without image formation at power-on or reset. At this time, the update storage operation during normal time when the cleaning blade is not pressed against the photoconductor and the update storage operation during cleaning when the cleaning blade is pressed against the photoconductor are performed in advance and stored in the storage means. Good. This makes it possible to form a high-quality image from the first image formation immediately after the power is turned on.

Further, if the image is not formed on the photoconductor while the cleaning blade is pressed against the photoconductor, the updating / storing operation by the correction value computing means 202 need not be performed only during this time. In this case, the storage means for cleaning is unnecessary. Further, even when it is known in advance that a load other than during cleaning will be applied, if the update storage operation is stopped only during that time, the speed fluctuation during image formation will not be worsened.

[0116]

As is clear from the description of the above embodiment,
A motor control device of the present invention includes a motor, a position detector that outputs a position signal according to the position of the motor, a speed detection unit that outputs a rotation speed of the motor from an output of the position detector, and the speed. In a motor control device having a speed control means for controlling the rotation speed of the motor to a predetermined speed command value according to the output of the detection means, the speed control means outputs the output of the speed detection means for each control cycle. Periodic control signal output means for outputting a control signal A so as to follow the speed command value, position control signal output means for outputting a control signal B according to the position of the position detector, and the periodic control signal output means. Control signal A of the position control signal output means and the control signal B of the position control signal output means are added to obtain the control signal of the motor, thereby suppressing rotation fluctuations such as cogging and torque ripple of the motor. It is an easily realized accurate speed control.

Further, in the image forming apparatus of the present invention, the photoconductor, the motor attached to the photoconductor, the position detector for outputting a position signal according to the position of the motor, and the output of the position detector. In the electrophotographic process having speed detection means for outputting the rotation speed of the motor, and speed control means for controlling the rotation speed of the motor to a predetermined speed command value according to the output of the speed detection means. The speed control means outputs a control signal A so that the output of the speed detection means follows the speed command value for each control cycle, and a control signal B corresponding to the position of the position detector. By adding the position control signal output means for outputting the control signal A of the cycle control signal output means and the control signal B of the position control signal output means to the control signal of the motor. An image forming apparatus for forming a high-quality image and makes it possible to be implemented in compact and lightweight.

[Brief description of drawings]

FIG. 1 is an overall view showing a configuration of a motor control device according to a first embodiment of the present invention.

FIG. 2 is a conceptual diagram of a position detector.

FIG. 3 is an explanatory diagram showing an example of a position signal output from a position detector.

FIG. 4 is an explanatory diagram showing an example of a velocity error waveform.

FIG. 5 is an overall view showing a configuration of a motor control device according to a second embodiment of the present invention.

FIG. 6 is an overall view showing a configuration of a motor control device according to a third embodiment of the present invention.

FIG. 7 is an overall view showing a configuration of a motor control device according to a fourth embodiment of the present invention.

FIG. 8 is an explanatory diagram showing an example of a speed error waveform before rotation fluctuation correction and a speed error waveform after filtering.

FIG. 9 is an explanatory diagram showing an example of a frequency analysis waveform of a speed error before rotation fluctuation correction.

FIG. 10 is an explanatory diagram showing operations of a filter and a position signal corrector.

FIG. 11 is an explanatory diagram showing an example of a speed error waveform after rotation fluctuation correction and a speed error waveform after filtering.

FIG. 12 is an explanatory diagram showing an example of a frequency analysis waveform of a speed error after rotation fluctuation correction.

FIG. 13 is an overall diagram showing a configuration of an image forming apparatus according to a fifth embodiment of the present invention.

FIG. 14 is an overall view showing a configuration of an image forming apparatus according to a sixth embodiment of the present invention.

FIG. 15 is an explanatory diagram showing a configuration of a motor controller 600 according to a sixth embodiment of the present invention.

FIG. 16 is an explanatory diagram showing a configuration of a conventional image forming apparatus.

[Explanation of symbols]

100,500 motor 102,502 Position detector 104 Current controller 106 Position signal processor 108 Differentiator 110 Cycle control signal output device 112 Position control signal output device 114,204 adder 200, 300 storage means 202 correction value calculation means 210 Averaging Means Offset Amount Discriminator 300 storage means 302 Filter 304 Position signal corrector 504 photoconductor 506, 600 motor controller 602 cleaning blade 604 Cleaning blade driver 606 Cleaning blade command device 610 Normal storage means 612 Storage means for cleaning 614, 616 Switching device

─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁷ Identification code FI theme code (reference) G05D 3/12 306 G03G 21/00 312 F term (reference) 2H027 DA17 DE07 ED02 ED27 EE04 EE08 EF09 2H035 CA07 CG01 2H134 GA01 GB02 HD00 HD18 KA15 KB14 KG08 KH01 KH13 5H303 AA01 AA21 AA27 CC01 CC06 DD01 FF05 FF16 GG09 JJ02 LL03 5H550 AA14 AA15 BB08 FF03 JJ25 JJ26 LL34 LL56 MM17

Claims (13)

[Claims] 1. A motor, a position detector that outputs a position signal according to the position of the motor, and speed detection means that outputs the rotation speed of the motor from the output of the position detector.
In a motor control device having a speed control means for controlling the rotation speed of the motor to a predetermined speed command value according to the output of the speed detection means, the speed control means includes a speed control means for the speed detection means for each control cycle. A cycle control signal output means for outputting a control signal A so that the output follows the speed command value; a position control signal output means for outputting a control signal B corresponding to the position of the position detector; and the cycle control signal. A motor control device, wherein the control signal A of the output means and the control signal B of the position control signal output means are added to obtain a control signal of the motor. 2. A position reference control signal storage means for storing a control signal B according to a position signal of the position detector, and the position detector stored in the position reference control signal storage means. Update storing means for updating and storing the control signal B according to the position signal of the control signal B using a correction signal composed of the output of the speed detecting means for each control cycle, and stored in the position reference control signal storing means. The motor control device according to claim 1, wherein the motor control device outputs a control signal B corresponding to the position signal of the position detector which is generated. 3. The number-of-times storage means for storing the number of invariants in which the position signal of the position detector at the control time A does not change from the position signal of the position detector in the control cycle before the control time A, and the update storage means. A correction signal averaging for obtaining the total sum of the correction signals composed of the outputs of all the speed detection means before the control time A, dividing the sum by the invariance count stored in the count storage means, and averaging The control signal B corresponding to the position signal of the position detector stored in the position reference control signal storage means is updated and stored by using the correction signal averaged by the correction signal averaging means. The motor control device according to claim 2, wherein 4. The update storage means includes a high frequency removal filter for removing high frequency components, and a position signal correction means for correcting the position signal of the position detector with the amount of positional deviation by the high frequency removal filter, A position reference according to the position signal corrected by the position signal correcting means using a high frequency removing correction signal obtained by removing a high frequency component by the high frequency removing filter from a correction signal composed of the output of the speed detecting means for each control cycle. The motor control device according to claim 2, wherein the control signal B stored in the control signal storage means is updated and saved. 5. The high frequency removing filter is an average value calculator for calculating an average value of the input values to the high frequency removing filter for a predetermined average number of times, and the position signal correcting means reduces the average number of times to half. 5. The motor control device according to claim 4, wherein the movement amount of the motor for a corresponding time is corrected as a positional deviation amount. 6. A motor, a position signal output device for outputting a plurality of sinusoidal signals having different phases according to the position of the motor, and a sinusoidal signal of the position signal output device divided into a plurality of parts. Position signal converter for converting into a position signal of the motor, speed detection means for outputting the rotation speed of the motor from the output of the position signal converter, and the rotation speed of the motor according to the output of the speed detection means. In a motor control device having a speed control means for controlling the speed command value to a predetermined speed command value, the speed control means controls the control signal A so that the output of the speed detection means follows the speed command value for each control cycle. A period control signal output means for outputting a position reference control signal storage means for storing a control signal B according to a position signal of the position converter, and a frequency of a signal output by the position signal output device. A high-frequency removal filter for removing components, a position signal correction means for correcting the position signal of the position converter by the amount of positional deviation by the high-frequency removal filter, and a correction signal composed of the output of the speed detection means for each control cycle. The control signal B stored in the position reference control signal storage means according to the position signal corrected by the position signal correction means is updated and saved by using the high frequency removal correction signal from which the high frequency component is removed by the high frequency removal filter. Update storage means, and adds the control signal A of the cycle control signal output means and the control signal B corresponding to the position signal of the position detector stored in the position reference control signal storage means. A motor control device characterized by using a control signal for the motor. 7. A photoconductor, a motor attached to the photoconductor, a position detector that outputs a position signal according to the position of the motor, and a rotation speed of the motor from the output of the position detector. In the electrophotographic process, the speed control means controls the rotation speed of the motor to a predetermined speed command value according to the output of the speed detection means. A period control signal output means for outputting a control signal A so that the output of the speed detection means follows the speed command value, and a position control signal output means for outputting a control signal B according to the position of the position detector. And the control signal A of the cycle control signal output unit and the control signal B of the position control signal output unit are added to obtain a control signal of the motor. 8. A position reference control signal storage means for storing a control signal B according to a position signal of the position detector, and the position detector stored in the position reference control signal storage means. Update storing means for updating and storing the control signal B according to the position signal of the control signal B using a correction signal composed of the output of the speed detecting means for each control cycle, and stored in the position reference control signal storing means. The image forming apparatus according to claim 7, wherein the image forming apparatus outputs a control signal B corresponding to the position signal of the position detector which is generated. 9. A photoconductor, a motor attached to the photoconductor, a position detector that outputs a position signal according to the position of the motor, and a rotation speed of the motor from the output of the position detector. Speed detecting means, speed controlling means for controlling the rotation speed of the motor to a predetermined speed command value according to the output of the speed detecting means, and load input means for inputting a load irrelevant to the position of the motor. In the electrophotographic process, the speed control means outputs a control signal A for each control cycle so that the output of the speed detection means follows the speed command value, and the position detector. Position reference control signal storage means for storing a control signal B in accordance with the position signal of the motor, and the position reference control signal storage means when the load input means does not input a load irrelevant to the position of the motor. Update saving means for updating and saving the control signal B corresponding to the position signal of the position detector stored in the quasi-control signal storage means using a correction signal composed of the output of the speed detecting means for each control cycle; An image forming apparatus, wherein a control signal A of a cycle control signal output means and a control signal B of the position reference control signal storage means are added to obtain a control signal of the motor. 10. A photoconductor, cleaning means for cleaning the photoconductor, a motor mounted on the photoconductor, a position detector for outputting a position signal according to the position of the motor, and the position detector. In the electrophotographic process having speed detection means for outputting the rotation speed of the motor from the output of, and speed control means for controlling the rotation speed of the motor to a predetermined speed command value according to the output of the speed detection means. A cycle control signal output means for outputting a control signal A so that the output of the speed detection means follows the speed command value for each control cycle; Cleaning position control signal output means for outputting a control signal B1 according to the position of the position detector, and the position detection when the cleaning means does not perform cleaning. A normal position control signal output means for outputting a control signal B2 according to the position of the container, and a control signal A for the cycle control signal output means and the cleaning position control signal output during cleaning by the cleaning means. The control signal B1 of the means is added, and when the cleaning means is not cleaning, the control signal A of the cycle control signal output means and the control signal B2 of the normal position control signal output means are added to add the control signal B1. An image forming apparatus comprising: a control signal switching unit that uses a motor control signal. 11. The cleaning position control signal output means stores the cleaning position reference control signal storage means for storing a control signal B1 in accordance with the position signal of the position detector, and the cleaning position control signal storage means, when cleaning is performed by the cleaning means. Update during cleaning, in which the control signal B1 corresponding to the position signal of the position detector stored in the during-cleaning position reference control signal storage means is updated and stored using a correction signal composed of the output of the speed detection means for each control cycle. The storage device has a storage unit, and the normal position control signal output unit performs cleaning by the normal position reference control signal storage unit that stores the control signal B2 according to the position signal of the position detector and the cleaning unit. When not present, the control signal B2 corresponding to the position signal of the position detector stored in the normal position reference control signal storage means is composed of the output of the speed detection means for each control cycle. That the correction signal image forming apparatus according to claim 10, wherein the has a normal update storage means for updating stored using the. 12. A cleaning position control signal output means stores cleaning position reference control signal storage means for storing a control signal B1 according to a position signal of a position detector, and a speed command value for a motor while cleaning by the cleaning means. And a control signal B1 corresponding to the position signal of the position detector stored in the cleaning position reference control signal storage means during the cleaning test operation by the cleaning test means. Has a cleaning-time update saving means for updating and saving using a correction signal composed of the output of the speed detecting means for each control cycle, and the normal time position control signal output means outputs the position signal of the position detector. Accordingly, the normal position reference control signal storage means for storing the control signal B2 and the communication for controlling the motor to the speed command value without cleaning by the cleaning means. A normal testing means for testing operation, during said normal test operation by conventional testing means, the control signal corresponding to the position signal stored in said normal position reference control signal memory means the position detector B2
11. The image forming apparatus according to claim 10, further comprising: a normal-time update saving unit that updates and saves the data by using a correction signal configured by the output of the speed detection unit for each control cycle. 13. A cleaning test operation by the cleaning test means and an update / save operation of the control signal B1 by the cleaning update save means, and a normal test operation by the normal test means and an update save operation of the control signal B2 by the normal time update save means. 13. The image forming apparatus according to claim 12, wherein the operation is performed at power-on or reset of the electrophotographic process.