JP2004157398A - Photoreceptor driving device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a photoreceptor driving device capable of restraining the influence of banding by restraining the speed variation of a driving control system/a driving transmission system. <P>SOLUTION: In the case of performing the position control of a photoreceptor driven by torque generated from a brushless motor 70, a control value for the position control is corrected so as to reduce the torque ripple of the brushless motor 70, whereby not only the photoreceptor driving device whose speed variation is restrained and whose banding is small is provided but also an image forming apparatus having high image quality is realized. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a photoconductor driving device used in an image forming apparatus such as a copying machine, and more particularly, to a photoconductor driving device that transfers a toner image onto a moving body such as an intermediate transfer belt or a paper conveyance belt. .
[0002]
[Prior art]
As a method of driving a photosensitive drum used in a conventional image forming apparatus or the like, a “rotary drum driving device” disclosed in Japanese Patent Application Laid-Open No. 2000-227738 is known. This rotary drum drive is driven by a brushless motor. In this conventional example, the rotor of the brushless motor is magnetized more finely than an ordinary rotor, and the stator is also formed with a concave and convex portion in order to increase the switching of energization.
For example, when the motor is rotated at 63 rpm by a normal brushless motor (for example, 8 poles and 3 coils), the energization switching frequency becomes
63/60 × 3 × (8/2) = 13 Hz
On the other hand, in the 100-pole 4-coil brushless motor used in the conventional rotary drum driving device,
63/60 × 4 × (100/2) = 210 Hz
Thus, the frequency can be increased to a level that is less likely to be affected by jitter (banding).
[0003]
[Patent Document 1]
JP 2000-227738 A
[Problems to be solved by the invention]
In general, it is widely known that the problems of a drive control system and a drive transmission system for realizing a high-quality image forming apparatus are to reduce banding and to reduce displacement.
However, if the rotor of the brushless motor is magnetized more finely than a normal rotor and the energization switching frequency can be controlled more finely as in the conventional example, the structure becomes complicated and the cost is disadvantageous. There was a problem that would.
[0005]
Accordingly, the present invention has been made in view of such a problem, and a photoreceptor capable of suppressing the fluctuation of the speed of a drive control system / drive transmission system and suppressing the effect of banding by reducing the torque ripple of a motor. It is an object to provide a driving device.
[0006]
[Means for Solving the Problems]
In order to solve the above-mentioned problem, the invention according to claim 1 is a photoconductor drive including a motor for driving a photoconductor, and a position control unit that controls a position of the photoconductor driven by torque generated from the motor. In the apparatus, the position control unit is a photoconductor driving device that corrects a control value so as to reduce a torque ripple of the motor.
The invention according to claim 2 is the photoconductor driving device according to claim 1, wherein the motor is configured by a brushless motor, and the position control unit is configured to control a Hall element signal of the brushless motor and a brushless motor of the brushless motor. The photoconductor driving device corrects the control value using a part of a reference sine waveform based on an encoder signal for detecting a position.
The invention according to claim 3 is the photoconductor driving device according to claim 1 or 2, wherein the position control device multiplies a part of the reference sine waveform by a coefficient to obtain position variation data. A photoconductor driving device that corrects the control value so as to be smaller.
The invention according to claim 4 is the photoconductor driving device according to any one of claims 1 to 3, wherein the frequency of the torque ripple is different from a natural frequency of a driving system including a driving target, a transmission system, and the motor. It is a photoconductor driving device that is set by setting.
[0007]
The invention according to claim 5 is the photoconductor driving device according to claim 1, wherein the motor is configured by a brushless motor, and the control unit detects a Hall element signal of the brushless motor and a position of the brushless motor. And a control unit that corrects a control value using a torque ripple waveform of the brushless motor in accordance with an encoder signal to be transmitted.
The invention according to claim 6 is the photoconductor driving device according to any one of claims 1 to 5, wherein the motor and the photoconductor are directly connected to a motor shaft of the motor. The drive is a photoconductor drive device.
The invention according to claim 7 is the photoconductor driving device according to any one of claims 1 to 6, wherein the photoconductor driving device is used in a tandem-type image forming apparatus.
[0008]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
First, an image forming apparatus to which the photoconductor driving device of the present invention is applied will be described with reference to FIGS.
2. Description of the Related Art In recent years, color image forming apparatuses, such as color copying machines and color printers, have been increasing in number in response to market requirements. A color image forming apparatus is provided with a plurality of color developing devices around one photoreceptor, and a toner is adhered by the developing devices to form a synthetic toner image on the photoreceptor, and the toner image is transferred. A so-called one-drum type in which a color image is recorded on a sheet and a plurality of photoconductors arranged side by side are provided with respective developing devices, and a single-color toner image is formed on each photoconductor, and the single-color toner image is formed. There is a so-called tandem type in which a composite color image is sequentially transferred and recorded on a sheet. Comparing the one-drum type and the tandem type, the former has a single photoreceptor, and thus has the advantage of being relatively small in size and reducing the cost. 4 times) Since full-color images are formed by repeating image formation, it is difficult to increase the speed of image formation. The latter, on the other hand, has the drawback of increasing the size and increasing the cost, but it is easy to increase the speed of image formation. There is an advantage that is. Since demand for full-color is required to be as fast as monochrome, a tandem type is attracting attention.
[0009]
As shown in FIG. 1, the tandem type image forming apparatus includes a sheet s which conveys an image on each photoreceptor 1 (1a to 1d) by a transfer device 2 (2a to 2d) by a sheet conveying belt 3. (Not shown), and an image on each photoreceptor 1 is temporarily transferred to an intermediate transfer body 10 by a primary transfer device 2 (not shown), as shown in FIG. After that, there is an indirect transfer type in which the image on the intermediate transfer body 10 is collectively transferred to a sheet s (not shown) by the secondary transfer device 22. In this case, the secondary transfer device 22 is the transfer conveyance belt 24, but there is also a method using a roller shape.
[0010]
Comparing the direct transfer type and the indirect transfer type, the former disposes the paper feeder 4 upstream of the tandem image forming apparatus 20 in which the photoconductors 1 are arranged and the fixing device 25 downstream thereof. And there is a disadvantage in that the size increases in the sheet conveying direction.
On the other hand, in the latter, the secondary transfer position can be set relatively freely. Therefore, the sheet feeding device 4 and the fixing device 25 can be disposed so as to overlap with the tandem image forming device 20, and there is an advantage that the size can be reduced.
In the former case, the fixing device 25 is disposed close to the tandem-type image forming device 20 in order not to increase the size of the fixing device 25 in the sheet conveying direction. Therefore, the fixing device 25 has a sufficient margin to allow the sheet s to bend. 25, the impact of the leading edge of the sheet s entering the fixing device 25 (particularly noticeable with a thick sheet), the sheet conveying speed when passing through the fixing device 25, the transfer conveying belt There is a disadvantage that the fixing device 25 tends to affect the image formation on the upstream side due to the speed difference from the sheet conveyance speed due to the above.
[0011]
On the other hand, in the latter, since the fixing device 25 can be arranged with a sufficient margin to allow the sheet s to bend, the fixing device 25 can hardly affect the image formation.
From the above, among the tandem-type image forming apparatuses, in particular, the indirect transfer type has recently attracted attention.
In this type of color image forming apparatus, as shown in FIG. 2, the transfer residual toner remaining on the photoconductor 1 after the primary transfer is removed by the photoconductor cleaning device 8 to clean the surface of the photoconductor 1, It was ready for another image formation. Further, the transfer residual toner remaining on the intermediate transfer body 10 after the secondary transfer is removed by the intermediate transfer body cleaning device 17 to clean the surface of the intermediate transfer body 10 and prepare for image formation again.
[0012]
FIG. 3 shows a tandem-type indirect transfer type image forming apparatus. In the figure, reference numeral 100 denotes a copying apparatus main body, 200 denotes a sheet feeding table on which the copying apparatus is mounted, 300 denotes a scanner mounted on the copying apparatus main body 100, and 400 denotes an automatic document feeder (ADF) mounted thereon.
An endless belt-shaped intermediate transfer body 10 is provided at the center of the copying apparatus main body 100. As shown in FIG. 4, the intermediate transfer member 10 is formed by forming a base layer 11 made of a non-stretchable material such as canvas on a low-elongation fluororesin or a high-elongation rubber material. 12 are provided. The elastic layer 12 is made of, for example, fluorine-based rubber or acrylonitrile-butadiene copolymer rubber. The surface of the elastic layer 12 is coated with, for example, a fluorine-based resin and covered with a coat layer 13 having good smoothness.
Then, as shown in FIG. 3, in the illustrated example, it can be rotated and conveyed clockwise in FIG. In the illustrated example, as shown in FIG. 2, an intermediate transfer body cleaning device 17 for removing residual toner remaining on the intermediate transfer body 10 after image transfer is provided to the left of the second support roller 15 among the three. . Among the three, the black (Bk), the yellow (Y), and the magenta are placed on the intermediate transfer member 10 extending between the first support roller 14 and the second support roller 15 along the transport direction. A tandem image forming apparatus 20 is configured by arranging four (M) and cyan (C) image forming units 18 side by side. On the tandem image forming apparatus 20, an exposing device 21 is further provided as shown in FIG.
[0013]
On the other hand, a secondary transfer device 22 is provided on the side opposite to the tandem image forming device 20 with the intermediate transfer member 10 therebetween. In the illustrated example, the secondary transfer device 22 is configured by wrapping a secondary transfer belt 24, which is an endless belt, between two rollers 23, and pressing the secondary transfer belt 24 against the third support roller 16 via the intermediate transfer body 10. The image on the intermediate transfer body 10 is transferred to a sheet. A fixing device 25 for fixing a transferred image on a sheet is provided beside the secondary transfer device 22. The fixing device 25 is configured by pressing a pressure roller 27 against a fixing belt 26 which is an endless belt. The above-described secondary transfer device 22 also has a sheet conveying function of conveying the sheet after image transfer to the fixing device 25. Of course, a transfer roller or a non-contact charger may be disposed as the secondary transfer device 22. In such a case, it is difficult to additionally provide the sheet conveying function, and therefore, the secondary transfer device 22 is separately provided.
In the illustrated example, a sheet reversing device that reverses the sheet so as to record an image on both sides of the sheet in parallel with the above-described tandem image forming device 20 under the secondary transfer device 22 and the fixing device 25. 28.
[0014]
Now, when making a copy using this color image forming apparatus, an original is set on the original table 30 of the automatic original feeder 400. Alternatively, the automatic document feeder 400 is opened, a document is set on the contact glass 32 of the scanner 300, and the automatic document feeder 400 is closed and pressed.
When a start switch (not shown) is pressed, when a document is set on the automatic document feeder 400, the document is conveyed and moved onto the contact glass 32, and then the document is set on the other contact glass 32. At this time, the scanner 300 is immediately driven to travel on the first traveling body 33 and the second traveling body 34. Then, the first traveling body 33 emits light from the light source and further reflects the reflected light from the document surface to the second traveling body 34, is reflected by the mirror of the second traveling body 34, and passes through the imaging lens 35. The original is read by a reading sensor 36 and read.
[0015]
When a start switch (not shown) is pressed, one of the support rollers 14, 15, 16 is rotationally driven by a drive motor (not shown), and the other two support rollers are driven to rotate. I do. At the same time, the photoreceptors 1 are rotated by the individual image forming means 18 to form black, yellow, magenta, and cyan monochromatic images on the respective photoreceptors 1. Then, as the intermediate transfer body 10 is transported, the monochrome images are sequentially transferred to form a composite color image on the intermediate transfer body 10.
[0016]
On the other hand, when a start switch (not shown) is pressed, one of the paper feed rollers 42 of the paper feed table 200 is selectively rotated, and a sheet is fed from one of the paper feed cassettes 44 provided in the paper bank 43 in multiple stages. The sheet is separated one by one into a sheet feeding path 46, conveyed by a conveying roller 47, guided to a sheet feeding path 48 in the copying machine main body 100, and stopped against a registration roller 49. Alternatively, the sheet feeding roller 50 is rotated to feed out the sheet on the manual feed tray 51, separated one by one by the separation roller 52, and then put into the manual sheet feeding path 53, and similarly hit against the registration roller 49 and stopped.
Then, the registration roller 49 is rotated in synchronization with the composite color image on the intermediate transfer body 10, the sheet is fed between the intermediate transfer body 10 and the secondary transfer device 22, and the sheet is transferred by the secondary transfer device 22. Record a color image on the sheet.
The sheet after the image transfer is conveyed by the secondary transfer device 22 and sent to the fixing device 25, where the transfer image is fixed by applying heat and pressure by the fixing device 25, and then switched by the switching claw 55 to discharge the sheet. The sheet is discharged at 56 and stacked on a sheet discharge tray 57. Alternatively, the sheet is switched into the sheet reversing device 28 by the switching claw 55, reversed and guided again to the transfer position, the image is recorded on the back surface, and then discharged onto the discharge tray 57 by the discharge roller 56.
[0017]
On the other hand, the intermediate transfer member 10 after the image transfer is removed by an intermediate transfer member cleaning device 17 to remove the residual toner remaining on the intermediate transfer member 10 after the image transfer, and the tandem image forming device 20 prepares for another image formation.
Here, the registration roller 49 is generally often used while grounded, but it is also possible to apply a bias voltage to remove paper dust from the sheet.
An embodiment in which the present invention is applied to the driving device of the photoconductor 1 in the image forming apparatus as described above will be described in detail with reference to the drawings.
[0018]
FIG. 5 is an explanatory diagram of the torque ripple of the brushless motor.
The excitation coils U, V, and W are energized as indicated by arrows by Hall element signals (not shown). At this time, torque ripple occurs because the magnetic flux density distribution of the rotor magnet (not shown) is not uniform. Therefore, even if a constant current is passed, speed fluctuation and position fluctuation occur.
Therefore, when used in a photoreceptor driving device, banding occurs when copying is performed due to fluctuations in drum speed.
[0019]
FIG. 6 is a diagram showing the torque ripple Tr and its correction waveform Ctr. At this time, when the electric angle is 120 degrees,
Tr = Kt × sin (θ) (1)
(However, π / 3 ≦ θ ≦ 2π / 3: Kt is a torque constant)
It becomes.
[0020]
Next, FIG. 7 shows the concept of the torque ripple correction method. Here, an example is shown in which a brushless motor having a torque ripple of 30 times per revolution (every mechanical angle of 12 degrees (0.2094 radians)) is used, and the brushless motor is rotating at 2 Hz (120 rpm).
FIG. 7A shows the relationship between the rotational position of the brushless motor and time. In this case, it is shown that the time advances by 1.256664 radians after 0.1 sec. FIG. 7B is a diagram showing each signal of the Hall elements Hu, Hv, Hw of the brushless motor, and FIG. 7C shows the rotation position of the brushless motor at the rise and fall of the Hall element signal. This is the case where the position is reset at the edge and the position is counted again. That is, when the Hall element signal is input and reset every mechanical angle of 12 degrees (0.2094 radians), and the position at that time is defined as θmr, when Kt = 1 in the above equation (1), that is, the torque ripple is reduced. The motor generated torque assuming a sine waveform is
Trm = sin (θe + π / 3) (2)
(However, θe = 5 × θmr)
It becomes.
[0021]
FIG. 8A shows the waveform of the motor-generated torque at this time, and FIG. 8B shows the correction signal Trc. From these, the following is derived.
Trc = 1 / Trm (3)
The motor generated torque Tm at this time is
Tm = Kt × Trm × Im (4)
Im indicates the motor current. Therefore, assuming that Im = Trc, the torque Tm generated by the motor is free from torque ripple, and Tm = Kt (5)
Therefore, no speed fluctuation due to torque ripple occurs.
[0022]
Accordingly, a control conceptual block diagram including the position feedback system and the Hall element signal is as shown in FIG.
On the other hand, at this time, the target position Refposi is expressed by the following equation when the time is tsec when the photoconductor linear velocity is 200 mm / sec and the photoconductor drum radius is Φ90 mm.
Refposi = 200/45 × t = 4.444 × t (6)
This is converted to a rotational speed of 0.707 Hz, and the open-loop transfer characteristic of the block diagram of FIG. 9 is as shown in FIG.
Thus, FIG. 10 shows the open-loop transfer characteristic from the target position to the measurement position, and the slope of the crossover frequency (45 Hz) is −20 dB, and stable position control can be realized. In other words, the photoconductor one rotation frequency (0.7074 Hz) is smaller than the crossover frequency, and the speed fluctuation due to the eccentric disturbance during one rotation of the photoconductor can be suppressed by the photoconductor axis feedback control.
Accordingly, the torque ripple correction calculation in FIG. 9 is performed as described above with reference to FIGS. 7 and 8 based on the rotation position of the motor and the Hall element signal.
[0023]
Here, the correction calculation processing will be described with reference to the flowchart of FIG. In the flowchart shown in FIG. 10, when the waveform of the torque ripple is Kt = 1 in the equation (1),
Tr = sin (θ) (7)
(However, π / 3 ≦ θ ≦ 2π / 3)
This is the process when it does not become. In other words, due to motor manufacturing variations, etc.
Tr = (1 ± △) × sin (θ) (8)
It is a flowchart for finding △ when becomes.
[0024]
First, the flowchart starts by performing the feedback control of the block diagram of FIG. 9 and rotating the motor.
In step S1, a correction waveform based on a sine waveform is read. That is, here, the reference correction waveform used when △ is 0 is described. Trc = 1 / Trm in the equation (3) is used.
Next, the routine proceeds to step S2, where it is determined whether or not the speed is a steady speed. Until the steady speed is reached, control is performed using the reference correction waveform used when △ previously read is 0. When it is confirmed that the steady speed has been reached, the process proceeds to step 3.
In step 3, the position fluctuation Xerror1, which is the difference between the target position and the measurement position, is measured. At this time, the position fluctuation of the frequency of the torque ripple may be extracted by Fourier transform.
[0025]
Subsequently, the process proceeds to step S4, in which the reference correction waveform is multiplied by a coefficient Ks1 of 1 or less. For example, if Ks1 = 0.8, the reference correction waveform is 0.8 × Trc.
Then, when the vehicle reaches the steady speed, the difference between the target position and the measured position and the position fluctuation Xerror2 are measured (step S5), and in the subsequent step S6, the position fluctuation Xerror1> the position fluctuation Xerror2 is compared.
If Xerror1 is larger, the process proceeds to step S7 to end the correction process, and Ks1 × Trc obtained in step S4 becomes a new reference correction waveform. Is the reference correction waveform when rotating.
[0026]
On the other hand, if Xerror2 is larger, the process proceeds to step S8, and a coefficient Ks2 that is equal to or larger than Ks1 and equal to or smaller than 1 is applied to the reference correction waveform. For example, Ks2 may be set to 0.9 between 0.8 and 1.
Then, when the steady speed is reached, the difference between the target position and the measured position and the position fluctuation Xerror3 are measured (step S9), and in the next step S10, the position fluctuation Xerror1> the position fluctuation Xerror2, 3 is compared.
If Xerror1 is larger, the process proceeds to step S13 to end the correction process, and Ks2 × Trc obtained in step S8 becomes a new reference correction waveform. Is the reference correction waveform when rotating.
The above is an example of finding a coefficient when the correction waveform is 1 or less. Here, Ks1 and Ks2 are considered for convenience, but Ks3, Ks4,. . . Needless to say, the measurement may be performed more finely by increasing the coefficient to be compared with.
[0027]
On the other hand, if Xerror3 is larger, the process proceeds to step S11, and the reference correction waveform is multiplied by one or more coefficients Kb1. For example, Kb1 = 1.2. The reference correction waveform at this time is 1.2 × Trc.
Then, when the steady speed is reached, the difference between the target position and the measured position and the position variation Xerror4 are measured (step S12), and in the subsequent step S13, Xerror1> Xerror4 is compared.
If Xerror1 is larger, the flow advances to step S18 to end the correction process, and Kb1 × Trc obtained in step S8 becomes a new reference correction waveform. Is the reference correction waveform when rotating.
[0028]
On the other hand, if Xerror4 is larger, the process proceeds to step S15, and a coefficient Kb2 of 1 or more and Kb1 or less is applied to the reference correction waveform. For example, Kb2 is set to 1.1 between 1 and 1.2.
When the steady speed is reached, the difference between the target position and the measurement position and the position fluctuation Xerror5 are measured (step S16), and in the subsequent step S17, Xerror1> Xerror5 is compared.
If Xerror1 is larger, the flow advances to step S19 to end the correction processing, and Kb2 × Trc obtained in step S15 becomes a new reference correction waveform. Is the reference correction waveform when rotating.
The above is an example of finding a coefficient when the correction waveform is 1 or more. As described above, two types of Kb1 and Kb2 have been considered for convenience here, but Kb3, Kb4,. . . It goes without saying that the measurement may be performed in detail by increasing the coefficient.
On the other hand, if Xerror1> Xerror5 is not satisfied even if the above is done, that is, if the speed fluctuation does not become small even if the coefficient is changed, the reference correction waveform is finally used.
[0029]
FIG. 12 shows a transfer characteristic of a photoconductor drive system using a timing belt and an analysis result thereof. As can be seen from FIG. 12A, it can be seen that there is a natural frequency near 500 radian / sec (80 Hz). Also, as shown in FIG. 12 (b), the FFT analysis of the speed fluctuation shows that the speed fluctuation of 80 Hz is large because the frequency 75 Hz of the torque ripple and the natural frequency 80 Hz are close. This also indicates that the frequency of the torque ripple needs to be set apart from the natural frequency of the drive system including the drive target, the transmission system, and the motor.
[0030]
FIG. 13 shows a waveform ftrl (θ) when the waveform of the torque ripple does not become the waveform of the sine. ftrl (θ) is data provided by the motor manufacturer. The correction waveform fctrl (θ) at that time may be the same as the correction data of the sine waveform described above.
FIG. 14 shows the configuration of the direct drive of the photoconductor. Reference numeral 70 denotes a brushless motor, 72 denotes a coupling that connects the shaft 71 of the brushless motor 70 and the shaft 73 of the photoconductor 74, and 75 denotes an encoder. Needless to say, the shaft 71 of the brushless motor 70 may be integrated with the shaft 73 of the photoconductor 74 instead of the coupling 72 in the figure.
[0031]
In the embodiment described above, when the position of the driven photoconductor is controlled by the torque generated from the brushless motor 70, the control value of the position control is corrected so as to reduce the torque ripple of the brushless motor 70. Accordingly, it is possible to provide a photoconductor driving device in which the speed fluctuation is suppressed and the banding is small. Thus, a high-quality image forming apparatus can be realized.
Further, as shown in FIG. 11, the correction value of the torque ripple can be changed to an appropriate value from the result of actually driving.
Further, by setting the torque ripple frequency apart from the natural frequency of the drive system including the drive target, the transmission system, and the motor, the speed fluctuation of the natural frequency can be suppressed.
[0032]
Further, by correcting the torque ripple from the actual torque ripple waveform data using the Hall element signal of the brushless motor and the encoder signal for detecting the position of the brushless motor, the speed fluctuation can be suppressed.
In addition, the brushless motor 70 and the photosensitive member 74 are directly connected to the shaft 71 of the brushless motor 70 by a coupling 72, and the natural frequency is increased as compared with the conventional timing belt drive by performing direct drive. As a result, the control band can be increased, so that speed fluctuations can be suppressed.
Furthermore, by using the photoconductor drive (drum drive) with the torque ripple correction applied to the tandem type drive device, the respective drums can be independently driven and controlled, so that the speed fluctuations of the four drums are synergistically suppressed and banding is small. A photoconductor driving device can be provided.
[0033]
【The invention's effect】
As described above, the photoconductor driving device of the present invention provides a photoconductor driving device that suppresses speed fluctuation and has small banding by correcting the control value of the position control so as to reduce the torque ripple of the motor. Accordingly, a high-quality image forming apparatus can be realized.
Further, the torque ripple correction value can be changed to an appropriate value from the result of actual driving. Further, by setting the torque ripple frequency apart from the natural frequency of the drive system including the drive target, the transmission system, and the motor, the speed fluctuation of the natural frequency can be suppressed. Further, by correcting the torque ripple from the actual torque ripple waveform data using the Hall element signal of the brushless motor and the encoder signal for detecting the position of the brushless motor, the speed fluctuation can be suppressed. Further, by using direct drive, the natural frequency can be increased as compared with the conventional timing belt drive, and the control band can be increased, so that speed fluctuation can be suppressed. Also, by using the photoconductor drive with the torque ripple correction applied to the tandem-type drive device, the respective drums can be independently driven and controlled, so that the speed fluctuation of the four drums is synergistically suppressed and the banding is small. Can be provided.
[Brief description of the drawings]
FIG. 1 is a schematic view of an image forming apparatus of a tandem type direct transfer system.
FIG. 2 is a schematic diagram of a tandem type indirect transfer type image forming apparatus.
FIG. 3 is a schematic diagram of a tandem type indirect transfer type image forming apparatus.
FIG. 4 is a sectional view of an intermediate transfer member.
FIG. 5 is an explanatory diagram of a torque ripple of the brushless motor.
FIG. 6 is an explanatory diagram of a torque ripple Tr and a correction waveform Ctr thereof.
FIG. 7A is a diagram showing the relationship between the rotational position of a brushless motor and time.
(B) The figure which shows the Hall element Hu, Hv, Hw of a brushless motor.
(C) The figure which shows the relationship between rotation of a brushless motor and a Hall element.
FIG. 8A is a waveform diagram of a motor generated torque.
(B) A waveform diagram of the correction signal Trc.
FIG. 9 is a control conceptual block diagram including a position feedback system and a Hall element signal.
FIG. 10 is a closed loop transfer characteristic diagram.
FIG. 11 is a flowchart for measuring a correction waveform.
FIG. 12A is a transfer characteristic diagram of a photoconductor driving system using a timing belt.
(B) FFT analysis of speed fluctuation.
FIG. 13 is a waveform chart when the waveform of the torque ripple does not become the waveform of the sine.
FIG. 14 is a schematic configuration diagram of direct drive of a photoconductor.
[Explanation of symbols]
1a to 1d Photoconductor (drum)
Reference Signs List 10 Intermediate transfer member 20 Image forming device 70 Brushless motor 75 Encoder 100 Copy device main body Hu, Hv, Hw Hall element of brushless motor

Claims (7)

A motor for driving the photoconductor, and a photoconductor driving device including a position control unit that controls a position of the photoconductor driven by torque generated by the motor;
The photoconductor driving device according to claim 1, wherein the position control unit corrects a control value so as to reduce a torque ripple of the motor. The motor is constituted by a brushless motor,
2. The apparatus according to claim 1, wherein the position control means corrects the control value using a part of a reference sine waveform based on a Hall element signal of the brushless motor and an encoder signal for detecting a position of the brushless motor. 3. The photoconductor driving device according to item 1. 3. The photosensitive device according to claim 1, wherein the position control device corrects the control value by multiplying a part of the reference sine waveform by a coefficient to reduce position variation data. 4. Body drive. 4. The photoconductor driving device according to claim 1, wherein a frequency of the torque ripple is set apart from a natural frequency of a driving system including a driving target, a transmission system, and the motor. . The motor is constituted by a brushless motor,
2. The photoconductor according to claim 1, wherein the control unit corrects a control value using a torque ripple waveform of the brushless motor based on a Hall element signal of the brushless motor and an encoder signal for detecting a position of the brushless motor. Drive. 6. The photoconductor driving device according to claim 1, wherein the motor and the photoconductor are a direct drive in which a photoconductor shaft of the photoconductor is directly connected to a motor shaft of the motor. 7. The photoconductor driving device according to claim 1, wherein the photoconductor driving device is used in a tandem image forming apparatus.

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