JP2007206120A - Drive controller and image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To ensure the stabilization of speed fluctuation in the rotational movement of an endless moving member generated by disk eccentricity of an encoder with a simple configuration. <P>SOLUTION: A control controller section 40 takes a difference e(n) between the target angular displacement received from a target angular displacement generation section 30 and a detected angular displacement received through a computing unit 700 from the encoder 31 (in actuality, an average value of the count values of the outputs of two sensors in a positional relation deviated by 180° of the encoder 31) and controls the drive of a drive motor 32 through a pulse output device 37 based on the difference e(n). <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a drive control device that drives and controls a drive roller that rotates an endless moving member such as a transfer conveyance belt used in a transfer device and the like, and image formation such as a color printer and a color copier equipped with the drive control device. Relates to the device.

  As a general method of forming a color image in a color image forming apparatus, a direct transfer method in which toner images formed in different colors on a plurality of photosensitive members are transferred while being directly superimposed on a transfer sheet, and toners having the same color There is an intermediate transfer method in which an image is transferred while being superimposed on an intermediate transfer member, and then transferred onto a transfer sheet at once. These methods are commonly called a tandem method because a plurality of photosensitive members are arranged side by side facing a transfer paper or intermediate transfer member. For each photosensitive member, yellow (Y), magenta (M), cyan (C ), An electrophotographic process such as formation and development of an electrostatic latent image is executed for each color of black (K), and on the transfer paper in the direct transfer method, the intermediate transfer in the intermediate transfer method Transfer on the body.

  In a tandem color image forming apparatus using each of these methods, an endless belt (endless belt) that runs while supporting transfer paper is used in the direct transfer method, and a photoconductor in the intermediate transfer method. It is common to employ an endless belt that receives and carries an image. Image forming units each including four photoconductors are arranged side by side along one running side of the endless belt.

  In the tandem color image forming apparatus, it is important to prevent the occurrence of color misregistration by accurately superimposing the toner images of the respective colors. Therefore, in any transfer system, an encoder is attached to one of the plurality of driven shafts constituting the transfer unit in order to avoid color misregistration due to the speed fluctuation of the transfer belt, and according to the rotational speed fluctuation of the encoder. Thus, feedback control of the rotational speed of the drive roller is an effective means.

  The most common method for realizing such feedback control is proportional control (PI control). First, the position deviation e (n) is calculated from the difference between the target angular displacement Ref (n) of the encoder and the detected angular displacement P (n-1) of the encoder. Then, a low-pass filter is applied to the position deviation e (n) of the calculation result to remove high frequency noise, a control gain is applied, and a certain standard drive pulse frequency is added. By controlling the drive motor that drives the drive roller based on the obtained drive pulse frequency, the encoder output can be controlled to always be driven at the target angular displacement.

As actual control, a counter that counts the rising edge of the output of the encoder pulse and a counter that counts every control cycle (for example, 1 ms) are used, and the calculation result of the target angular displacement that moves during the control cycle (1 ms) The position deviation can be acquired from the difference from the detected angular displacement obtained by acquiring the encoder count value for each control cycle.
A specific calculation is as follows when the roller diameter of the driven shaft to which the encoder is attached is φ15.615.

e (n) = θ0 × q−θ1 × ne [rad]
The meaning of each symbol in this formula is as follows.
e (n) [rad]: Position deviation calculated in the current sampling θ0 [rad]: Movement angle per control cycle (= 2π × V × 10 ⁻³ /15.615π [rad])
θ1 [rad]: Movement angle per pulse of encoder (= 2π / p [rad], where p is the slit pitch of the encoder)
q: Count value of control cycle timer ne: Encoder count value V: Belt linear velocity [mm / s]

Here, for example, assuming that the encoder has a control period of 1 ms and the resolution of the encoder is 300 pulses per revolution, and the feedback control is performed so that the transfer belt operates at 162 mm / s, the following is assumed.
θ0 = 2π × 162 × 10 ⁻³ /15.615π=0.0207487 [rad]
θ1 = 2π × p = 2π / 300 = 0.0209439 [rad]
A position deviation is acquired by performing the above calculation for every control period, and feedback control is performed.

  In a general encoder configuration, a disk having a radial slit that transmits light with a resolution of several hundred units in the circumferential direction is press-fitted into a driven roller shaft. This disk rotates at the same time as the driven roller, and a pulse signal (pulsed ON / OFF signal) corresponding to the amount of rotation of the driven roller can be obtained by detecting the slit with a sensor. The rotational speed of the driving roller is controlled by detecting the moving angle of the driven roller using this pulse signal.

  However, due to the influence of the concentricity processing accuracy of the disk of the encoder, when the disk is mounted on the driven roller, it may be mounted in a state shifted from each other. When rotating in this state, the driven roller is rotated at a constant speed, but the disk is rotated in an eccentric state. When this is read by a sensor (light receiver), one rotation component of the disk is output to the sensor output, that is, a pulse signal. Further, since one rotation component is amplified by feedback control to rotate the driving roller, the transfer belt speed fluctuates every time the disk rotates, and color misregistration occurs.

  Originally, in feedback control, we would like to improve the response to load fluctuations by increasing the control gain. However, if the control gain is increased, one rotation component of the disk increases, resulting in increased color misregistration. Had to perform feedback control with a low control gain. For this reason, the removal of other variable components that are originally desired to be controlled has not been sufficiently performed.

As a method for controlling the speed fluctuation of the transfer belt caused by the eccentricity of the disk attached to the driven roller described above, for example, there is one described in Patent Document 1. This is because the driving roller is rotated at a constant speed, the angular velocity information obtained from the encoder output is acquired for at least one driving roller cycle, and the first half portion and the latter half portion are added by dividing the driving roller by one-half cycle. The offset speed fluctuation component caused by the drive roller is canceled out, and only the speed fluctuation caused by the driven roller is extracted. Further, at the time of image formation, the speed running of the belt is made constant by taking the difference between the angular velocity information detected from the driven roller and the speed fluctuation.
JP 2000-47547 A

  The control method described in Patent Document 1 measures the encoder pulse interval with a constant clock, and subtracts the encoder speed fluctuation when the drive roller is rotated at a constant speed from the encoder speed when feedback control is performed, The speed control is performed to cancel the speed fluctuation caused by the disk eccentricity and to keep the speed of the encoder constant. To achieve this control, at least a clock rate that can sufficiently sample the influence of the eccentric component of the disk from the pulse interval of the encoder, high-speed hardware that can process it, and measurements such as high-resolution counters and timers Means are required, resulting in an expensive system, which is disadvantageous in terms of cost.

  Further, as described above, the position deviation e (n) is calculated from the difference between the target angular displacement Ref (ni) of the encoder and the detected angular displacement P (n−1) of the encoder, and the drive pulse of the drive motor is calculated from the calculation result. In the case of position control for controlling the frequency, the methods described in Patent Documents 1 and 2 cannot be applied in the first place.

  The present invention has been made to solve such a problem, and is a target roller in an image forming apparatus or the like (for example, a driving roller for rotating an endless moving member such as a transfer conveying belt or the rotation of the endless moving member) In the drive control device that drives and controls the drive roller based on the output signal of the encoder that detects the circumferential motion of the driven roller that is driven and rotated by the rotation of the endless moving member that is caused by the eccentricity of the disk of the encoder, The purpose is to ensure that the configuration can be used.

In order to achieve the above object, the present invention provides the following drive control device and an image forming apparatus including the same.
The drive control apparatus according to the first aspect of the present invention includes a drive roller that rotates the endless moving member or an encoder that detects the peripheral movement of the driven roller that rotates following the rotation of the endless moving member, and outputs an output signal of the encoder. A drive control device for driving and controlling the drive roller based on the encoder, wherein the encoder includes a disk having a plurality of marks or slits arranged at predetermined intervals in the circumferential direction and a pair for detecting each mark or slit. And each sensor is mounted at a position shifted by 180 degrees, and each of the sensors counts the output of each sensor, and each count value obtained by the counting means is sampled at a predetermined timing. And an average value of each count value sampled by the sampling means An average calculation section that, by performing feedback control on the control target value based on the average value calculated by the average value calculating means, is provided with a feedback control means for driving and controlling the drive rollers.

The drive control apparatus according to a second aspect of the present invention is the drive control apparatus according to the first aspect, wherein when the average value calculating means calculates the average value of the count values sampled by the sampling means, the respective count values are calculated. The value is added and weighted.
According to a third aspect of the present invention, there is provided a drive control apparatus according to the second aspect, further comprising preadjustment mode setting means for setting a preadjustment mode for determining the weighting.

A drive control device according to a fourth aspect of the present invention is the drive control device according to any one of the first to third aspects, wherein the feedback control means is configured such that when one of the pair of sensors becomes unusable, The feedback control is performed using the output signal of the other sensor.
A drive control device according to a fifth aspect of the present invention is the drive control device according to any one of the first to fourth aspects, wherein the feedback control means stops the feedback control when the pair of sensors become unusable. It is what I did.

An image forming apparatus according to a sixth aspect of the invention includes the drive control device according to any one of the first to fifth aspects, and an endless moving member for image formation that is driven and controlled by the drive control device.
According to a seventh aspect of the present invention, in the image forming apparatus of the sixth aspect, the endless moving member is any one of a photosensitive belt, a transfer belt, an intermediate transfer belt, and an image recording medium conveying belt. That's it.

  According to the drive control device of the present invention, the encoder that detects the circumferential movement of the target roller (the driving roller that rotates the endless moving member or the driven roller that rotates following the rotation of the endless moving member) includes a plurality of marks or The disk includes a disk in which slits are arranged at predetermined intervals in the circumferential direction and a pair of sensors for detecting each mark or slit, and each sensor is mounted at a position shifted by 180 degrees. A counting unit that counts the output of each sensor, a count value by the counting unit is sampled at a predetermined timing, an average value of each sampled count value is calculated, and a control target is calculated based on each calculated average value. Since the drive roller is controlled by performing feedback control on the value, the encoder The stabilization of the speed fluctuation of the endless moving member generated by disk runout Da, can be reliably performed with a simple configuration. According to the image forming apparatus of the present invention, it is possible to perform appropriate processing according to the image quality at a low cost by including the drive control device.

Hereinafter, the best mode for carrying out the present invention will be specifically described with reference to the drawings.
[First embodiment]
First, a configuration example of an image forming apparatus provided with a drive control apparatus according to the present invention will be described with reference to FIGS. This image forming apparatus is a color laser printer (hereinafter referred to as “laser printer”) that forms a color image by a direct transfer type electrophotographic method, and FIG. 2 is a schematic configuration diagram of the entire laser printer.

As shown in FIG. 2, the laser printer includes four sets of toner image forming units 1 (1Y) for forming images of each color of Y (yellow), M (magenta), C (cyan), and K (black). , 1M, 1C, 1K) are arranged in order from the upstream side (lower right side in the figure) in the direction in which the transfer paper P moves as the transfer conveyance belt 60 travels along the arrow A in the figure.
Each toner image forming unit 1 includes a photosensitive drum 11 (11Y, 11M, 11C, 11K) as an image carrier and a developing unit 12. The arrangement of the toner image forming units 1 is set so that the rotation axes of the photosensitive drums 11 are parallel to each other and arranged at a predetermined pitch in the transfer paper moving direction.

  In addition to the toner image forming unit 1, this laser printer carries an optical writing unit 2, paper feed cassettes 3 and 4, a registration roller pair 5, and a transfer paper (image recording medium) P to form each toner image. Belt driving device 6 equipped with a transfer conveyance belt (which combines the functions of a transfer belt and an image recording medium conveyance belt) 60 as an endless moving member that conveys the paper so as to pass through the transfer position of the belt, belt fixing type fixing A unit 7 and a paper discharge tray 8 are provided. The belt drive device 6 is a combination of a control system (drive control device) described later, and also functions as a transfer unit.

The laser printer further includes a manual feed tray 14 and a toner replenishing container 22, and a waste toner bottle, a duplex / reversing unit, a power supply unit, and the like (not shown) are also provided in a space S indicated by a two-dot chain line.
The optical writing unit 2 includes a light source, a polygon mirror, an f-θ lens, a reflection mirror, and the like, and irradiates the surface (outer peripheral surface) of each photosensitive drum 11 while scanning with laser light based on image data. .

FIG. 3 is an enlarged view showing a schematic configuration of the belt driving device 6 described above.
The transfer conveying belt 60 used in the belt driving device 6 is a high-resistance endless single-layer endless belt (endless belt member) having a volume resistivity of 10 ⁹ to 10 ¹¹ Ωcm, and the material thereof is, for example, PVDF (Polyvinylidene fluoride). The transfer conveyance belt 60 is stretched around support rollers 61 to 66 so as to pass through the transfer positions that are in contact with and face the photosensitive drum 11 of the toner image forming units 1.

  An electrostatic attraction roller 80 is provided so as to face the entrance roller 61 located upstream of the support rollers 61 to 66 in the transfer paper moving direction on the outer peripheral surface side of the transfer conveyance belt 60. Yes. A predetermined voltage is applied to the electrostatic attraction roller 80 by the power supply 18, and the transfer paper P that has passed between the two rollers 61 and 80 is charged and electrostatically adsorbed onto the transfer conveyance belt 60. The driving roller 63 is a driving roller that frictionally drives the transfer conveyance belt 60, and is rotated in the direction of arrow D by a driving motor (described later).

  The transfer bias applying member 27 (27Y, 27M, 27C, 27K) as transfer electric field forming means for forming a transfer electric field is brought into contact with the back surface of the transfer conveyance belt 60 at each transfer position facing each photoconductor drum 11. Is provided. These transfer bias applying members 27 are bias rollers provided with a sponge or the like on the outer periphery, and a transfer bias voltage is applied to the roller core from each transfer bias power source 9 (9Y, 9M, 9C, 9K). By the action of the applied transfer bias voltage, a transfer charge is applied to the transfer conveyance belt 60, and a transfer electric field having a predetermined intensity is generated between the surface of the transfer conveyance belt 60 and the surface of the photosensitive drum 11 at each transfer position. It is formed. In addition, a backup roller 68 is provided in order to keep the contact between the transfer paper and the photosensitive drum 11 in an area where the transfer is performed, and to obtain the best transfer nip.

  Each transfer bias applying member 27 and the backup roller 68 disposed in the vicinity thereof are respectively integrally held by a swing bracket 93 so as to be rotatable, and can be rotated around a rotation shaft 94. This rotation is clockwise when the cam 96 fixed to the cam shaft 97 is rotated in the direction of arrow E.

  The entrance roller 61 and the electrostatic attraction roller 80 described above are integrally supported by the entrance roller bracket 90, and can be rotated clockwise from the state of FIG. A pin 92 projecting from the entrance roller bracket 90 is fitted into a hole 95 provided in the swing bracket 93, and the entrance roller bracket 90 also rotates in conjunction with the rotation of the swing bracket 93. . By rotating the brackets 90 and 93 in the clockwise direction, the respective transfer bias applying members 27 and the backup rollers 68 disposed in the vicinity thereof are separated from the photosensitive drum 11, and the entrance roller 61 and the electrostatic adsorption roller 80. Also move downwards. This makes it possible to avoid contact between the photosensitive drums 11Y, 11M, and 11C and the transfer conveyance belt 60 when an image is formed using only black toner.

  On the other hand, the transfer bias applying member 27K and the backup roller 68 adjacent to the transfer bias applying member 27K are rotatably supported by the outlet bracket 98, and are rotatable about a shaft 99 coaxial with the outlet roller 62. When the belt driving device 6 is attached to or detached from the laser printer main body, the exit bracket 98 is rotated clockwise by the operation of a handle (not shown), and the transfer conveying belt 60 is moved together with the transfer bias applying member 27K and the backup roller 68. It can be separated from the photosensitive drum 11K for black image formation.

As shown in FIG. 2, a cleaning device 85 including a brush roller and a cleaning blade is disposed on the outer peripheral surface of the portion of the transfer conveyance belt 60 wound around the driving roller 63. The cleaning device 85 removes foreign matters such as residual toner adhering to the transfer / conveying belt 60.
A roller 64 is provided so as to push the outer peripheral surface of the transfer conveyance belt 60 immediately downstream of the drive roller 63 in the traveling direction of the transfer conveyance belt 60, and a large winding angle of the transfer conveyance belt 60 with respect to the drive roller 63 is ensured. Yes. A tension roller 65 that is in contact with the inner peripheral surface of the transfer conveyance belt 60 and is pressed outward by the biasing force of a spring 69 that is a pressing member to apply tension to the transfer conveyance belt 60 is provided immediately downstream of the roller 64. It is arranged.

Next, an image forming operation by this laser printer will be described.
At the time of image formation by this laser printer, the transfer paper P is fed from one of the paper feed cassettes 3 and 4 and the manual feed tray 14 shown in FIG. 2, and is guided to a conveyance guide (not shown) along a conveyance path indicated by a one-dot chain line. And is conveyed to a temporary stop position where the registration roller pair 5 is provided.

  On the other hand, at the time of color image formation, the photosensitive drums 11 (11Y, 11M, 11C, 11K) of the four sets of toner image forming units 1 (1Y, 1M, 1C, 1K) are rotated clockwise in FIG. After the surface is uniformly charged by a charging member (not shown), the optical writing unit 2 irradiates and scans the surface with laser light modulated by data of each color of the image to be formed, A latent image is written. Thereafter, the toner is developed with toner of each color by the developing unit, and a toner image of each color is formed on the surface of each photoconductive drum 11.

The transfer paper P sandwiched between the registration roller pair 5 and temporarily stopped as described above is sent out at a predetermined timing by the registration roller pair 5 and is carried on the transfer conveyance belt 60 toward each toner image forming unit 1. It is sequentially conveyed and passes through each transfer nip. The toner images of the respective colors formed on the photosensitive drums 11 of the respective toner image forming units 1 are formed at sequentially shifted image forming timings so as to be superimposed on the transfer paper P at the respective transfer nips. When the transfer paper P passes through each transfer nip, it is transferred onto the transfer paper P under the action of the transfer electric field and nip pressure. A full color toner image is formed on the transfer paper P by this superposition transfer.
The surface of each photosensitive drum 11 after the toner image transfer is cleaned by a cleaning device 13 and is further discharged to prepare for the formation of the next electrostatic latent image.

  On the other hand, the transfer paper P on which the full-color toner image is formed is fixed in the first paper discharge direction B or the second in accordance with the rotation posture of the switching guide 21 after the full-color toner image is fixed by the fixing unit 7. In the paper discharge direction C. When the paper is discharged from the first paper discharge direction B onto the paper discharge tray 8, it is stacked in a so-called face-down state with the image surface down. On the other hand, when the paper is discharged in the second paper discharge direction C, it is conveyed toward another post-processing device (not shown) (such as a sorter or a binding device) or printed on both sides via a switchback unit. It is again conveyed to the registration roller pair 5.

As described above, this laser printer forms a full-color image on the transfer paper P.
In such a tandem image forming apparatus, it is important to prevent the occurrence of color misregistration by superimposing toner images of respective colors with high positional accuracy. However, the driving roller 63, the entrance roller 61, the exit roller 62, and the transfer / conveying belt 60 used in the belt driving device 6 cause a manufacturing error of several tens of μm at the time of manufacturing the parts. Due to this error, a fluctuation component generated when each part makes one rotation is transmitted to the transfer conveyance belt 60, and the transfer speed of the transfer paper varies.

Due to the change in the transfer paper conveyance speed (the rotation speed of the transfer conveyance belt 60), when the toner image on each photoconductive drum 11 is transferred to the transfer paper P, a subtle shift occurs in the timing. Color misregistration occurs in the direction (transfer paper transport direction). In particular, in an apparatus that forms an image with minute dots such as 1200 × 1200 DPI, a deviation in timing of several μm is conspicuous as a color deviation.
Therefore, in the belt driving device 6 (including the drive control device) in the first embodiment, the detection signal (output) of the encoder provided on the shaft of the lower right driven roller (referred to as “lower right roller”) 66 in FIG. The rotation speed of the lower right roller 66 is detected by a pulse signal), and the rotation of the driving roller 63 is feedback-controlled, so that the transfer conveyance belt 60 is driven at a constant speed.

FIG. 4 is a perspective view illustrating the entire configuration of the belt driving device 6 through the transfer conveyance belt 60.
The drive roller 63 is connected to the drive motor 32 via the timing belt 33 and is driven to rotate in proportion to the rotational speed of the drive motor 32. The transfer conveyance belt 60 is frictionally rotated by the rotation of the driving roller 63, and the lower right roller 66 is frictionally rotated by the rotation of the transfer conveyance belt 60. As described above, in the first embodiment, the encoder 31 is provided on the shaft of the lower right roller 66 (target roller), and based on the rotational speed of the lower right roller 66 detected from the detection signal of the encoder 31. The speed control of the drive motor 32 is performed. As described above, this is performed in order to suppress color misregistration due to positional variation (rotational variation) of the transfer conveyance belt 60.

FIG. 5 is a perspective view showing a configuration example of the lower right roller 66 and the encoder 31 of FIG.
6A and 6B are diagrams showing a configuration example of the disk 311 and the sensor in the encoder 31. FIG. 6A is a front view of only the disk 311 and FIG. 6B is a side view of the disk 311 and the sensor.
FIG. 7 is a diagram showing different examples of sampling results when the drive motor 32 of FIG. 4 is driven at a constant speed and the count value of the output pulse of the encoder 31 is sampled at a constant timing (predetermined timing).

For example, as shown in FIGS. 5 and 6, the encoder 31 includes a disk 311, two light emitting elements 312 and 316, two light receiving elements 313 and 317, and press-fit bushings 314 and 315.
The disk 311 is fixed by press-fitting press-fitting bushes 314 and 315 onto the shaft of the lower right roller 66, and rotates simultaneously with the rotation of the lower right roller 66.
Further, the disk 311 is formed with radial slits that transmit light with a resolution of several hundred units in the circumferential direction, and a light emitting element 312 that constitutes a pair, that is, two encoder sensors, on both sides thereof. The element 313, the light emitting element 316, and the light receiving element 317 are arranged at positions shifted by 180 degrees, and the light receiving elements 313, 317 cause the number of pulse signals (pulse-like ON / OFF) corresponding to the rotation angle of the lower right roller 66 OFF signal) is generated. The drive amount of the drive motor 32 is controlled by detecting the movement angle (hereinafter referred to as “angular displacement”) of the lower right roller 66 using the pulse signal.

  By the way, an error of several μm occurs in the machining of the coaxial hole when the disk 311 is press-fitted into the lower right roller 66, and it is practically impossible to make it zero. Therefore, when the disk 311 is attached to the lower right roller 66, the disk 311 may be attached so as to be displaced from each other. When the disk 311 is rotated in this state, the disk 311 is rotated at a constant speed even though the lower right roller 66 is rotating at a constant speed. 311 is rotated in an eccentric state. When this is read by the encoder sensor (light receiving elements 313, 317), angular displacement fluctuations occur every cycle (one rotation) of the disk 311.

In FIG. 7, (a) shows the sampling result when there is no eccentricity of the disk 311 and (b) shows the sampling result when there is eccentricity. Usually, when there is no eccentricity of the disk 311, a sampling result that rises to the right is obtained, but when there is eccentricity, a sine wave sampling result is obtained.
Since the sampling result indicates the detected angular displacement of the encoder 31, the fact that the sampling result is sinusoidal indicates that the detection position error is large accordingly. When the machining accuracy error of the coaxial hole of the disk 311 is large, the amplitude of the sine wave is detected to be larger.

  Since the two light receiving elements 313 and 317 are arranged at positions shifted by 180 degrees, the phase of the sine wave of the sampling result is shifted by 180 degrees. Therefore, by calculating the average value of the two sampling results, it is possible to cancel the angular displacement fluctuation due to the eccentricity of the disk 311. In this first embodiment, the two sampling results are calculated by an arithmetic unit (average value is calculated), thereby performing proportional control calculation not affected by the eccentricity of the disk 311 and rotating the transfer conveyance belt 60. It is characterized by a constant speed.

FIG. 8 is a block diagram illustrating a hardware configuration example of a control unit including the drive motor control unit (drive control device) of the belt drive device 6 described above in the laser printer.
The drive motor control unit of the belt drive device 6 digitally controls the drive pulse of the drive motor 32 based on the output pulse signals of the two encoder sensors 331 and 332 (each composed of a light emitting element and a light receiving element) constituting the encoder 31. To do.

The control unit 600 including the drive motor control unit includes a CPU 601, a RAM 602, a ROM 603, an IO control unit 604, a motor drive I / F unit 606, a driver 607, a detection IO unit 608, and a bus 609.
The CPU 601 controls the entire laser printer based on the program in the ROM 603, including receiving image data from an external device 38 such as a personal computer and control of transmission / reception of control commands to / from the external device 38. Central processing unit.

The CPU 601 operates in accordance with a program in the ROM 603 and uses the encoder sensor 331 and the like, thereby functioning as means according to the present invention, that is, sampling means, average value calculating means, feedback control means, and pre-adjustment mode setting means. Can be fulfilled.
A RAM 602, a ROM 603, an IO control unit 604, a motor drive I / F unit 606, and a detection IO unit 608 are connected to the CPU 601 via a bus 609.
A RAM 602 is a readable / writable memory (storage means) used as a work memory used when the CPU 601 performs control (processing) or an image memory when developing image data.

The ROM 603 is a read-only memory that stores fixed data such as programs executed by the CPU 601 (for the CPU 601 to operate).
The IO control unit 604 controls input / output of signals to / from each load 39 such as a motor, a clutch, a solenoid, and a sensor in accordance with an instruction from the CPU 601.
The motor drive I / F unit 606 is driven by outputting a drive pulse signal to the drive motor 32 (drive roller 63) for rotating the transfer conveyance belt 60 via the driver 607 in response to a drive command from the CPU 601. The rotational drive of the motor 32 is controlled. Since this rotation driving is performed according to the frequency of the drive pulse signal, the rotation speed of the transfer conveyance belt 60 can be variably controlled.

Two encoder sensors 331 and 332 (each composed of a light emitting element and a light receiving element) constituting the encoder 31 are connected to a detection IO unit 608, and output pulse signals (encoder pulses) of the encoder sensors 331 and 332 are respectively Input to the detection IO unit 608.
The detection IO unit 608 processes the output pulses of the encoder sensors 331 and 332, respectively, and converts them into digital values. The detection IO unit 608 includes a plurality of counters (described later) including two counters (hereinafter referred to as “encoder pulse counters”) that respectively count (count) the output pulses of the encoder sensors 331 and 332. . The values of the encoder pulse counters (number of output pulses of the encoder sensors 331 and 332) are sent to the CPU 601 via the bus 609.

  The CPU 601 performs arithmetic processing for calculating an average value of the values of the encoder pulse counters based on the values of the encoder pulse counters. Then, the calculation result is multiplied by a predetermined pulse number diagonal displacement conversion constant to be converted into a digital value corresponding to the angular displacement of the shaft of the lower right roller 66 (FIG. 5). The value obtained here corresponds to P (n-1) described later, and feedback control is performed by the control method described with reference to FIG.

Here, the motor drive I / F unit 606, the driver 607, and the RAM 602 will be described in a little more detail.
When the motor drive I / F unit 606 receives a drive command (including a drive frequency instruction) from the CPU 601 via the bus 609, the motor drive I / F unit 606 generates a pulsed control signal having a drive frequency instructed based on the drive command. And outputs it to the driver 607.

  The driver 607 is configured by a power semiconductor element (for example, a transistor) or the like, operates based on a pulsed control signal input from the motor drive I / F unit 606, and outputs a drive pulse signal to the drive motor 32. . Specifically, a pulsed drive voltage is applied. As a result, the drive motor 32 is driven and controlled at a speed proportional to the drive frequency instructed by the drive command of the CPU 601. As a result, the additional value is controlled so that the angular displacement of the disk 311 of the encoder 31 becomes the target angular displacement, and the lower right roller 66 rotates at a constant angular velocity at a predetermined angular velocity. The angular displacement of the disk 311 is detected by the encoder sensors 331 and 332 and the detection IO unit 608 and is taken in by the CPU 601 and the control is repeated.

In addition to functions used as a work memory and an image memory when the CPU 601 controls (executes a program in the ROM 603), the RAM 602 controls the drive motor 32 at a constant speed without executing an image forming process in advance. It has a function as a data memory for storing detected angular displacement error data for one rotation of the disk corresponding to the disk eccentricity of the encoder 31 measured by driving.
Since the RAM 602 is a volatile memory, the detected angular displacement error data is stored in a nonvolatile memory such as an EEPROM (not shown), and the detected angular displacement error is detected when the power is turned on or the drive motor 32 is started. Data can also be expanded on the RAM 602.

  By the way, in the proportional control calculation generally used for the feedback control of the drive motor, as described above, the control gain is applied to the difference between the target angular displacement and the detected angular displacement for each control cycle to control the drive speed of the drive motor. If the detected angular displacement error due to the disk eccentricity of the encoder is large, it will be further amplified and drive the drive motor. For this reason, the position of the transfer / conveyance belt 60 varies every rotation of the disk, and color misregistration occurs.

Further, as described above, FIG. 7B shows the behavior when the drive motor 32 is driven at a constant speed. In other words, the count value of the pulse number of the encoder 31 is sampled at a constant timing. If the result is as shown in FIG. 7B, the lower right roller 66 is rotating at a constant speed.
Therefore, in the first embodiment, as shown in FIG. 7B, the target angular displacement for each control cycle (actually, the control target value that makes the angular displacement per unit time of the encoder 31 constant). Is obtained by adding the detected angular displacement error to the target angular displacement), the angular displacement of the encoder 31 corresponding to the target angular displacement is detected by the encoder sensor 331, and the proportional control is not affected by the eccentricity of the disk 311. By calculating and controlling the drive motor 32, the rotation speed of the transfer conveyance belt 60 is made constant.

FIG. 1 is a schematic functional block diagram showing a configuration for explaining functions of an embodiment of a drive control apparatus according to the present invention. This embodiment shows an example when the present invention is applied to the control of the belt driving device 6 described above.
In FIG. 1, the control controller unit 40 includes a subtraction circuit 41, a low-pass filter 42 for removing high-frequency noise, a proportional calculation unit (gain Kp) 43, a steady drive pulse frequency setting unit 44, and an addition circuit 45. And is composed of. The control controller 40, the target angular displacement generator 30, and the pulse output device 37 are executed by the CPU 601 in FIG. 8 executing the program in the ROM 603 and using the motor drive I / F unit 606, the driver 607, and the detection IO unit 608. Can be realized.

  The target angular displacement generation unit 30 drives the drive motor 32 at a constant speed without executing the image forming process, and the detected angular displacement error caused by the disk eccentricity of the encoder 31 measured in advance is used as a characteristic value in the memory 301 (FIG. 8). (Corresponding to a data memory in the RAM 602). Then, during the image forming process, a reference mark on the disk 311 indicating the reference position is detected by a mark sensor (not shown), for example, and a mark detection signal output from the mark sensor is input from the memory 301 at a predetermined timing. Read characteristic values sequentially. This is performed by sequentially switching the reference address of the memory 301 from the detection timing of the reference position of the disk 311. Thereafter, the read characteristic value is added to the target angular displacement which is the control target value to obtain a new target angular displacement Ref (n), which is input to the control controller unit 40.

Here, the addition of the detected angular displacement error and the target angular displacement is performed in accordance with, for example, the timing at which the reference mark is detected by the mark sensor every rotation of the disk 311 and the mark detection signal output from the mark sensor is input. Is performed periodically.
The target angular displacement generation unit 30 holds the target angular displacement Ref (n) obtained by adding the detected angular displacement error measured in advance in the memory 301, and at the predetermined timing (for example, the disk 311) during the image forming process. The target angular displacement Ref (n) may be read out by sequentially switching the reference address of the memory 301 from the reference position detection timing) and input to the control controller unit 40.

The control controller 40 receives the target angular displacement Ref (n) that is the control target value input from the target angular displacement generator 30 and the detected angular displacement P received from the encoder sensors 331 and 332 of the encoder 31 via the calculator 700. (N-1) is input to the subtraction circuit 41 and the difference e (n) is obtained. That is, the difference displacement amount is calculated. The detected angular displacement P (n−1) is actually calculated based on the output pulse signals of the encoder sensors 331 and 332, which will be described in detail later.
The difference e (n) is input to the proportional calculation unit 43 after high frequency noise is removed by passing through the low-pass filter 42.

The proportional calculation unit 43 proportionally amplifies the difference e (n) from the low-pass filter 42 with the gain Kp, and supplies the result to the addition circuit 45 as a correction amount (rad) Hz.
The adder circuit 45 determines the drive pulse frequency f (n) by adding the correction amount (rad) Hz from the proportional calculation unit 43 to the constant steady drive pulse frequency (Refpc) Hz from the steady drive pulse frequency setting unit 44. Then, it is output to the pulse output device 37.
The pulse output unit 37 generates a drive pulse signal having the drive pulse frequency f (n) received from the adder circuit 45 and outputs it to the drive motor 32.

  Therefore, the control controller unit 40 calculates the calculation result of the calculator 700, that is, the average value of the output pulse signals of the encoder sensors 331 and 332 (reception elements 313 and 317) sampled at a predetermined timing (composite count value). ) Is calculated, and feedback control for the control target value is performed based on the calculated value, and the drive motor 32, that is, the transfer conveyance belt 60 is driven and controlled.

  FIG. 9 shows an example of a timing chart for realizing the drive control according to the present invention. Although not shown in FIG. 8, it is assumed that the control unit 600 is provided with a control cycle timer for measuring time. The detection IO unit 608 is provided with two encoder pulse counters and a control cycle timer counter, which will be described later.

  First, in FIG. 9, the count values of the two encoder pulse counters that respectively count the encoder pulses of the two encoder sensors 331 and 332 of the encoder 31 are incremented (+1) by the rising edge of the output of the corresponding encoder pulse. The control cycle of this control is 1 ms, and the count value of the control cycle timer counter is incremented (+1) every time the CPU 601 is interrupted by the control cycle timer.

The time measurement of the control cycle timer is started when the rising edge of the encoder pulse is detected for the first time after the through-up and settling of the drive motor 32 is completed, and the count value of the control cycle timer counter is reset to “0”. .
Also, every time the CPU 601 is interrupted by the control cycle timer, the control cycle timer counter count value: q is acquired, the encoder pulse counter count values: ne ⁺ , ne ⁻ are acquired, and increment (+1) is performed. . Note that ne ⁺ and ne ⁻ correspond to values obtained from the two encoder sensors 331 and 332, and in the first embodiment, an average value is calculated from these values. The calculation formula is as follows.
ne = (ne ⁺ + ne ⁻ ) / 2

As a result, the CPU 601 calculates the position deviation as follows.
P (n−1) = θ1 × ne
Ref (n) = θ0 × q
e (n) = Ref (n) -P (n-1) (unit: rad)

Here, the meaning of each symbol in the above formula is as follows.
e (n) [rad]: Position deviation (calculated in this sampling) θ0 [rad]: Movement angle per control period 1 [ms] (= 2π × V × 10 ⁻³ / Lπ [rad])

θ1 [rad]: Movement angle per encoder pulse (= 2π / p [rad])
q: Count value of control cycle timer V: Belt linear velocity [mm / s]
L: Lower right roller diameter [mm]
f: Disk rotation period [Hz]

In the first embodiment, the diameter of the lower right roller, which is a driven roller to which the encoder 31 is attached, is φ15.515 [mm]. The resolution p of the encoder 31 is assumed to be 300 pulses per revolution.
Next, in order to avoid responding to sudden position fluctuations, it is preferable to perform filter calculation and gain calculation of the following specifications for the calculated deviation.

Filter type: Butterworth IIR low-pass filter Sampling frequency: 1 KHz (= equal to control period)
Passband ripple (Rp): 0.01 dB
Stop band end attenuation (Rs): 2 dB
Passband edge frequency (Fp): 50 Hz
Stopband edge frequency (Fs): 100Hz

A block diagram of the filter operation is shown in FIG. 10, and a list of filter coefficients is shown in FIG. Two stages of filters having the same configuration are cascade-connected, and intermediate nodes in each stage are u1 (n), u1 (n-1), u1 (n-2) and u2 (n), u2 (n-1), u2 respectively. (N-2). Here, the meaning of the index is as follows.
(N): Current sampling (n-1): Previous sampling (n-2): Second previous sampling

The following program calculation is performed each time a control timer interrupt occurs during feedback execution.
u1 (n) = a11 * u1 (n-1) + a21 * u1 (n-2) + e (n) * ISF
e1 (n) = b01 * u1 (n) + b11 * u1 (n-1) + b21 * u1 (n-2)
u1 (n-2) = u1 (n-1)
u1 (n-1) = u1 (n)
u2 (n) = a12 * u2 (n-1) + a22 * u2 (n-2) + e1 (n)
e '(n) = b02 * u2 (n) + b12 * u2 (n-1) + b22 * u2 (n-2)
u2 (n-2) = u2 (n-1)
u2 (n-1) = u2 (n)
FIG. 12 shows the amplitude characteristics of this filter, and FIG. 13 shows the phase characteristics.

Next, the control amount for the controlled object is obtained. In the control block diagram, first, considering PID control as a position controller,
F (S) = G (S) × E ′ (S) = Kp × E ′ (S) + Ki × E ′ (S) / S + Kd × S × E ′ (S)
However, Kp: proportional gain, Ki: integral gain, Kd: differential gain.
G (S) = F (S) / E ′ (S) = Kp + Ki / S + Kd × S (1)

Here, when the bilinear transformation (S = (2 / T) × (1-Z ⁻¹ ) / (1 + Z ⁻¹ )) is performed on the equation (1), the following equation is obtained.
G (Z) = (b0 + b1 * Z- ¹ + b2 * Z- ² ) / (1-a1 * Z- ^1- a2 * Z- ² ) (2)
However, a1 = 0
a2 = 1
b0 = Kp + T × Ki / 2 + 2 × Kd / T
b1 = T × Ki−4 × Kd / T
b2 = −Kp + T × Ki / 2 + 2 × Kd / T

Expression (2) is represented as a block diagram as shown in FIG. Here, e ′ (n) and f (n) indicate that E ′ (S) and F (S) are treated as discrete data, respectively. In FIG. 14, when w (n), w (n−1), and w (n−2) are determined as intermediate nodes, the difference equation is as follows (general expression for PID control).
w (n) = a1 * w (n-1) + a2 * w (n-2) + e '(n) (3)
f (n) = b0 * w (n) + b1 * w (n-1) + b2 * w (n-2) (4)
Here, the meaning of the index is as follows.
(N): Current sampling (n-1): Previous sampling (n-2): Second previous sampling

Considering proportional control as a position controller, the integral gain and derivative gain are zero. Accordingly, the coefficients in FIG. 14 are as follows, and the expressions (3) and (4) are simplified as the following expression (5).
a1 = 0 a2 = 1 b0 = Kp b1 = 0 b2 = -Kp
w (n) = w (n−2) + e ′ (n)
f (n) = Kp × w (n) −Kp × w (n−2)
→ ∴f (n) = Kp × e ′ (n) (5)

Also, the discrete data f0 (n) corresponding to F0 (S) is constant in the case of the first embodiment,
f0 (n) = 6105 [Hz]
It is. Therefore, the pulse frequency set in the drive motor 32 is finally calculated by the following equation (6).
f ′ (n) = f (n) + f0 (n) = Kp × e ′ (n) +6105 [Hz] (6)

FIG. 15 shows an operation flowchart of the two encoder pulse counters described above. In the flowchart of FIG. 15 and the flowchart described below, each step is abbreviated as “S”.
First, it is determined whether or not the first pulse (either one of the two encoder pulses) after the through-up and settling of the drive motor 32 is input (S1). If YES, the two encoder pulse counters are reset (S2). Then, the control cycle timer counter is reset (S3), interrupt by the control cycle timer is permitted (S4), the control cycle timer is started (S5), and the process returns to the main routine (not shown). If the determination in step 1 is NO, the corresponding encoder pulse counter is incremented (S6), and the process returns to the main routine.

FIG. 16 shows a flowchart of interrupt processing by the control cycle timer.
First, it increments the control cycle timer counter (S21), followed by two encoder pulse count ^ne +, ne ^- acquires (S22), + the respective encoder pulse count ^ne, ne ^- Synthesis count is the average value The value ne = (ne ⁺ + ne ⁻ ) / 2 is calculated (S23). Further, the value of Δθ is acquired by referring to the table data (S24), and the table data reference address is incremented (S25). Next, a position deviation calculation is performed using these values (S26), a filter calculation is performed on the obtained position deviation (S27), and a control amount calculation (proportional calculation) is performed based on the result of the filter calculation. (S28). Then, the frequency of the drive pulse of the drive motor 32 (stepping motor) is actually changed (S29), and the process returns to the main routine.

With the above control, it is possible to appropriately perform the control for stabilizing the rotational speed of the transfer conveyance belt 60 generated by the disk eccentricity of the encoder 31 in the position control at a low cost and according to the image quality.
[Second Embodiment]
Next, a second embodiment will be described. Since only the operation is slightly different from the first embodiment, only the different parts will be described.
Here, in the case of the first embodiment, it is assumed that the two encoder sensors 331 and 332 arranged in the encoder 31 are always in positions where the phases are shifted by 180 degrees. However, accurately maintaining the arrangement of the encoder 31 during mass production may lead to an increase in cost and has a limit.

  Therefore, in order to cope with the problem even if the accuracy is lowered, in the second embodiment, the calculation formula used for the calculation by the calculator 700 for the count values of the two encoder pulse counters is changed. In the first embodiment, the average value of the count values of the two encoder pulse counters is calculated. However, if the phase accuracy cannot be obtained, the sin wave-like fluctuation width shown in FIG. Comes out. Even if ones having different amplitudes are combined, the count waveform as shown in FIG. 2A is not obtained. Therefore, the following arithmetic expression is used in the second embodiment.

ne = (α · ne ⁺ + β · ne ⁻ ) / 2
However, α + β = 1
That is, it is a calculation incorporating weights for each count value. Thereby, the transition of the composite count value ne becomes as shown in FIG. 7A, and the control for stabilizing the rotation speed of the transfer conveyance belt 60 irrespective of the processing accuracy of the encoder sensors 331 and 332 is performed. Is possible. The actual values of α and β are determined by measuring ne when the device is driven at a constant speed at no load before shipping the device to which the present invention is applied, such as a laser printer. By passing through the adjustment process in the line, it is possible to absorb component variations. During the adjustment process, a pre-adjustment mode for determining the values of α and β (determining the weight for each count value) is set by an operation on an operation unit (not shown) of the device.

[Third embodiment]
Next, a third embodiment will be described. Since the operation is slightly different from the first embodiment or the second embodiment, only the different portions will be described.
If there is an abnormality in the output of the two encoder sensors 331 or 332, it may become a factor that breaks the drive system for feedback control, so error handling is an essential item in the product.

  Therefore, in the third embodiment, when one of the encoder sensors 331 and 332 becomes unusable, the count value of the output of the other encoder sensor is used as the composite count value. Since it is output from 700, the feedback control is performed using the combined count value. When both the encoder sensors 331 and 332 are disabled, the feedback control is stopped. Specifically, the value of the difference e (n) between the target angular displacement Ref (n) and the detected angular displacement P (n−1) of the encoder 31 is always set to “0”. The above-described operation can actually be realized by monitoring whether or not a normal pulse has come in S1 of FIG.

  In the first to third embodiments described above, the lower right roller 66 among the driven rollers that are driven to rotate by the rotation of the transfer conveyance belt is the target roller to which an encoder is attached. A driving roller that rotates the belt may be a target roller. In addition, as an encoder, a disk on which a radial mark that reflects light with a resolution of several hundred units in the circumferential direction is formed, and two sensors (each of which is arranged to face the mark portion at a position shifted by 180 degrees) It is also possible to use a device including a light emitting element and a light receiving element.

  As described above, the embodiment in which the present invention is applied to the drive control device (belt drive device) for driving and controlling the transfer conveyance belt has been described. However, the present invention is not limited to this, and other endless moving members (photosensitive members) for image formation. The present invention can also be applied to a drive control device that drives and controls a body belt, a transfer belt, an intermediate transfer belt, or an image recording medium conveyance belt.

That is, an example in which the present invention is applied to a belt driving device in a tandem type laser printer in which a plurality of photosensitive drums 11Y, 11M, 11C, and 11K are arranged on the transfer conveyance belt 60 has been described. Possible image forming apparatuses and belt driving apparatuses are not limited to this configuration.
As long as the image forming apparatus has a belt driving device that rotationally drives an endless belt stretched around a plurality of rollers by at least one of the rollers (target roller), any of the belt driving devices Is also applicable.

In each of the above-described embodiments, the present invention is applied to a direct transfer type color printer in which transfer paper is transported by the transfer transport belt 60 and four color toner images from the photosensitive drum are sequentially transferred onto the transfer paper. However, the present invention is also applied to an intermediate transfer belt driving device in an indirect transfer type color printer or the like that transfers four color toner images onto an intermediate transfer belt, superimposes the four colors, and transfers them onto a transfer sheet at once. Applicable.
Furthermore, although laser light is used as the exposure light source in the above-described embodiments, the present invention is not limited to this, and for example, an LED array or the like may be used as the light source.

As is apparent from the above description, according to the drive control device of the present invention, it is possible to perform control that stabilizes the rotational speed fluctuation of the endless moving member caused by the disk eccentricity of the encoder at a low cost, Good feedback control can be performed. Therefore, if this invention is utilized, the drive control apparatus which can implement | achieve stabilization of the rotational speed of an endless moving member at low cost can be provided.
According to the image forming apparatus of the present invention, an endless moving member (photosensitive belt, transfer belt, intermediate transfer belt, or image recording medium conveying belt) generated by the disk eccentricity of the encoder is obtained by using the drive control device. Control for stabilizing the fluctuation of the rotation speed can be appropriately performed at low cost according to the image quality. Therefore, if this invention is used, an image forming apparatus capable of acquiring a high-quality image at a low cost can be provided.

It is a typical functional block diagram which shows the structure for demonstrating the function of one Embodiment of the drive control apparatus by this invention. 1 is a schematic configuration diagram of an entire laser printer showing an example of an image forming apparatus including a drive control device according to the present invention. FIG. 3 is an enlarged view showing a schematic configuration of a belt driving device 6 shown in FIG. 2. FIG. 6 is a perspective view showing the configuration of the transfer conveying belt 60 in the belt driving device 6 as seen through.

FIG. 5 is a perspective view illustrating a configuration example of a lower right roller 66 and an encoder 31 illustrated in FIG. 4. It is a figure which shows the example of a structure of the disk 311 in the encoder 31, and a sensor. FIG. 5 is a diagram showing different examples of sampling results when the drive motor 32 of FIG. 4 is driven at a constant speed and the count value of the output pulse of the encoder 31 is sampled at a constant timing.

It is a block diagram which shows the hardware structural example of the control part containing the drive motor control part of the belt drive device 6 in the laser printer shown in FIG. It is a timing chart for demonstrating the belt drive control by this invention. It is a block diagram which shows the structure of the filter calculation used for this invention. It is a table figure which similarly shows the filter coefficient list.

It is a diagram which similarly shows the amplitude characteristic of the filter. It is a diagram which similarly shows the phase characteristic of the filter. It is a block diagram which shows the structure of the 1st stage filter calculation in FIG. It is an operation | movement flowchart of two encoder pulse counters. It is a flowchart of a control cycle timer interrupt process.

Explanation of symbols

1Y, 1M, 1C, 1K: toner image forming unit 6: belt driving device 30: target angular displacement generating unit 31: encoder 32: driving motor 37: pulse output device 40: control controller unit 60: transfer conveyance belt 63: driving roller 66: Lower right roller (driven roller) 311: Disks 331, 332: Encoder sensor 600: Control unit 601: CPU
602: RAM 603: ROM 604: IO control unit 606: Motor drive I / F unit 607: Driver 608: Detection IO unit 609: Bus 700: Calculator

Claims (7)

Drive control for driving and controlling the drive roller based on an output signal of the encoder, the drive roller for rotating the endless moving member or the encoder for detecting the peripheral movement of the driven roller rotated by the rotation of the endless moving member A device,
The encoder has a disk in which a plurality of marks or slits are arranged at predetermined intervals in the circumferential direction, and a pair of sensors for detecting the marks or slits, and the sensors are shifted by 180 degrees. It has a configuration attached to
Counting means for counting the outputs of the pair of sensors,
Sampling means for sampling each count value by the counting means at a predetermined timing, and
An average value calculating means for calculating an average value of each count value sampled by the sampling means;
A drive control apparatus comprising: feedback control means for drivingly controlling the drive roller by performing feedback control on the control target value based on the average value calculated by the average value calculating means. The drive control device according to claim 1,
The drive control apparatus according to claim 1, wherein the average value calculating means calculates the average value of the count values sampled by the sampling means and adds the weighted values to the count values. The drive control apparatus according to claim 2, wherein
A drive control apparatus comprising a pre-adjustment mode setting means for setting a pre-adjustment mode for determining the weighting. In the drive control device according to any one of claims 1 to 3,
The drive control device, wherein the feedback control unit performs the feedback control using an output signal of another sensor when one of the pair of sensors becomes unusable. In the drive control device according to any one of claims 1 to 4,
The drive control device, wherein the feedback control unit stops the feedback control when the pair of sensors become unusable.   An image forming apparatus comprising: the drive control device according to claim 1; and an endless moving member for image formation that is driven and controlled by the drive control device. The image forming apparatus according to claim 6.
The image forming apparatus, wherein the endless moving member is at least one of a photosensitive belt, a transfer belt, an intermediate transfer belt, and an image recording medium conveyance belt.

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