JP2006244314A - Drive controller and image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To surely stabilize fluctuation in rotational speed of an endless movement member due to disk eccentricity of an encoder by a simple configuration. <P>SOLUTION: A controller part 40 finds a difference e(n) between a target angular displacement received from a target angular displacement generation part 30 and a detected angular displacement received from the encoder 31 via an output composition circuit 700. Actually, the detected angular displacement is calculated based on an output signal from the encoder 31. Based on the difference e(n), the controller part 40 controls drive of a drive motor 32 via a pulse output apparatus 37. The output composition circuit 700 composes an output signal for two sensors, which are shifted from each other at 180 degrees, inside the encoder 31 to output the composed signal after multiplying it by 1/2. <P>COPYRIGHT: (C)2006,JPO&NCIPI

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 control resolution is 300 ms and the encoder resolution 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.

  A general encoder configuration is configured such that 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 and rotated simultaneously with the driven roller. By detecting the slit with a sensor, a pulse signal (pulsed ON / OFF signal) corresponding to the rotation amount of the driven roller can be obtained. 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.

Alternatively, as a control method that is not affected by the eccentricity of the disk attached to the driven roller, for example, there is a method described in Patent Document 2. This is because a linear scale is partially formed along the circumferential direction of the endless belt or drum, and a plurality of timing marks printed on the linear scale are detected by a plurality of sensors during one rotation of the endless belt or drum. At least two sensors detect, output a pulse signal as a speed signal from the encoder based on the output pulse of each sensor, and a controller generates a control signal for making the difference between the pulse signal and the command pulse signal zero. The surface speed of the endless belt or drum is controlled to be constant by generating and driving the drive motor in accordance with this control signal.
JP 2000-47547 A JP 2004-69933 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 2 for detecting each mark or slit. Each sensor is mounted at a position shifted by 180 degrees, a combining means for combining the output signals of the two sensors, and a multiplication for multiplying the combined signal from the combining means by 1/2 Means, a counting means for counting the composite signal multiplied by 1/2 from the multiplication means, and a count value by the means at a predetermined timing. Sampling means for grayed, by performing feedback control on the control target value based on the sampled counted value by the sampling means, it 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 a delay means is provided between the two sensors and the synthesizing means, and the delay means receives the output signals of the two sensors. When changing at the same time, the output of either one of the signals is delayed.
According to a third aspect of the present invention, there is provided a drive control apparatus according to the first or second aspect, wherein the delay amount of the output of the one signal by the delay means is constant, and the feedback control means is provided with a filter calculation means. Is.

A drive control apparatus according to a fourth aspect of the present invention is the drive control apparatus according to any one of the first to third aspects, wherein the feedback control means is configured such that when one of the two sensors becomes unusable, The feedback control is performed using only the output signal of the other sensor.
According to a fifth aspect of the present invention, in the drive control apparatus according to any one of the first to fourth aspects, the feedback control means stops the feedback control when the two 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 motion 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 A disk having slits arranged at predetermined intervals in the circumferential direction and two sensors for detecting each mark or slit are provided, and each sensor is attached at a position shifted by 180 degrees. The output signals of two sensors are combined, the combined signal is multiplied by 1/2, the combined signal multiplied by 1/2 is counted, the count value is sampled at a predetermined timing, and based on the sampled count value The drive roller is driven and controlled by performing feedback control with respect to the control target value. The stabilization of the speed fluctuation of the endless moving member for generating Te, 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, 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 an electrophotographic method of a direct transfer 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. A 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 sheet 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 along a dashed line while being guided by a conveyance guide (not shown). 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 drive roller 63, the entrance roller 61, the exit roller 62, and the transfer / conveying belt 60 used in the belt drive device 6 are subject to a manufacturing error of several tens of μm when parts are manufactured. 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 paper conveyance speed fluctuates.

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 timing shift of several μm is conspicuous as a color shift.
Therefore, in the belt drive device 6 (including the drive control device) in this embodiment, the detection signal (output pulse signal) of the encoder provided on the shaft of the lower right driven roller (referred to as “lower right roller”) 66 in FIG. ), The rotational speed of the lower right roller 66 is detected, and the rotation of the driving roller 63 is feedback-controlled, so that the transfer conveyance belt 60 runs 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 this embodiment, the encoder 31 is provided on the shaft of the lower right roller 66 (target roller), and the drive motor is based on the rotational speed of the lower right roller 66 detected from the detection signal of the encoder 31. 32 speed controls are 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 and a light receiving element 313 that respectively constitute two encoder sensors. And 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 and 317 provide a number of pulse signals (pulsed ON / OFF signals) corresponding to the rotation angle of the lower right roller 66. ). 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 combining these two sampling results, it is possible to cancel the angular displacement fluctuation due to the eccentricity of the disk 311. In this embodiment, the two sampling results are synthesized by an output synthesis circuit, which will be described later, so that proportional control calculation that is not affected by the eccentricity of the disk 311 is performed and the rotation speed of the transfer conveyance belt 60 is made constant. It is characterized by.

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. In FIG. 8, only one encoder sensor is shown for convenience of illustration, but it is assumed that there are actually two encoder sensors.
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 signal of each encoder sensor 331 (each composed of a light emitting element and a light receiving element).

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 drive motor IF 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 can function as each means according to the present invention, that is, a sampling means and a feedback control means by using the encoder sensor 331 and the like.
A RAM 602, a ROM 603, an IO control unit 604, a drive motor IF 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 drive motor IF 606 outputs 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, thereby rotating the drive motor 32. Control the drive. 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.

The output pulse signal of the encoder sensor 331 is input to the detection IO unit 608.
The detection IO unit 608 processes the output pulse of the encoder sensor 331 and converts it into a digital value. The detection IO unit 608 includes a plurality of counters (described later) including a counter that counts (counts) the output pulses of the encoder sensor 331. Then, a digital value corresponding to the angular displacement of the shaft of the lower right roller 66 (FIG. 5) is obtained by multiplying the counter value (the number of output pulses of the encoder sensor 331) by a predetermined pulse number diagonal displacement conversion constant. Convert to A digital value signal corresponding to the angular displacement of the disk 311 of the encoder 31 is sent to the CPU 601 via the bus 609.

Here, the drive motor IF 606, the driver 607, and the RAM 602 will be described in a little more detail.
When the drive motor IF 606 receives a drive command (including a drive frequency instruction) from the CPU 601 via the bus 609, the drive motor IF 606 generates a pulse-like control signal having a drive frequency instructed based on the drive command. Output to the driver 607.

  The driver 607 is configured by a power semiconductor element (for example, a transistor) or the like. The driver 607 operates based on a pulsed control signal input from the drive motor IF 606, and outputs a drive pulse signal to the drive motor 32 (applies a pulsed drive voltage). 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 sensor 331 and the detection IO unit 608 and is taken in by the CPU 601 and the control is repeated.

The RAM 602 drives the drive motor 32 at a constant speed without executing an image forming process in advance, 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). Function as a data memory in which detected angular displacement error data (data sampled at fixed intervals) corresponding to one disk revolution (one revolution) corresponding to the disk eccentricity of the encoder 31 measured at the time of measurement) have.
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. As a result, the position of the transfer / conveying belt 60 (change in rotational speed) occurs every rotation (one cycle) 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 this embodiment, as shown in FIG. 7B, the target angular displacement for each control cycle (actually, the control target value is such that the angular displacement per unit time of the encoder 31 is constant). The detected angular displacement error is added to the target angular displacement), and the angular displacement of the encoder 31 corresponding to the target angular displacement is detected by the encoder sensor 331, and is not affected by the disk eccentricity (the eccentricity of the disk 311). The rotation speed of the transfer conveyance belt 60 is made constant by controlling the drive motor 32 by performing a proportional control calculation.

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 controller section 40 includes a subtracting circuit 41, a low-pass filter 42 for removing high-frequency noise, a proportional calculation section (gain Kp) 43, a steady drive pulse frequency setting section 44, and an adding circuit. 45. The control controller unit 40, the target angular displacement generation unit 30, and the pulse output unit 37 are realized by the CPU 601 in FIG. 8 executing the program in the ROM 603 and using the drive motor IF 606, the driver 607, and the detection IO unit 608. can do.

  The target angular displacement generation unit 30 uses the detected angular displacement error caused by the disk eccentricity of the encoder 31 (measured when the drive motor 32 is driven at a constant speed without executing the image forming process) as a characteristic value in the memory 301 ( (Corresponding to the data memory in the RAM 602 in FIG. 8). During the image forming process, the memory 301 is detected according to a predetermined timing, for example, a reference mark (reference position) of the disk 311 is detected by a mark sensor (not shown) and a mark detection signal output from the mark sensor 332 is input. The characteristic values are sequentially read from the disk (the characteristic values are read by sequentially switching the reference address of the memory 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, for adding the characteristic value (detection angular displacement error) and the target angular displacement, for example, a reference mark is detected every rotation of the disk 311 by a mark sensor (not shown), and a mark detection signal output from the mark sensor is input. It is performed so as to be repeated periodically according to the timing.
Note that the target angular displacement generation unit 30 holds the target angular displacement Ref (n) obtained by adding the detected angular displacement error (characteristic value) measured in advance in the memory 301, and the predetermined timing ( For example, the target angular displacement Ref (n) may be read out by sequentially switching the reference address of the memory from the detection timing of the reference position of the disk 311 and input to the control controller unit 40.

The control controller 40 receives the target angular displacement Ref (n), which is a control target value input from the target angular displacement generator 30, and the detected angular displacement P () received from the encoder sensor 331 of the encoder 31 via the output synthesis circuit 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 signal of the encoder sensor 331, 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.

FIG. 9 is a block diagram illustrating a configuration example of the output synthesis circuit 700 of FIG.
The output synthesis circuit 700 includes a determination circuit 701, a delay circuit 702, a synthesis circuit 703, and a multiplication circuit 704.
The determination circuit 701 is a determination unit. When each output pulse signal (detection angular displacement P (n−1)) of the light receiving elements 313 and 317 of each encoder sensor 331 is input, the rising edge of each output pulse signal ( ON) It is determined whether or not the timings overlap.

When it is determined that the rising timings of the output pulse signals of the light receiving elements 313 and 317 are not overlapped, the output pulse signals are output to the synthesis circuit 703 as they are. When it is determined that the rising timings of the output pulse signals of the light receiving elements 313 and 317 overlap (when the output pulse signals change simultaneously), the output pulse signal that has risen first is directly sent to the synthesis circuit 703. The output pulse signal that rises with a delay is output to the delay circuit 702, respectively.
The delay circuit 702 is a delay unit and delays the output pulse signal input from the determination circuit 701 and outputs the delayed output pulse signal to the synthesis circuit 703. Note that the delay amount is constant.

  The synthesizing circuit 703 is a synthesizing unit, and synthesizes and outputs the input output pulse signals. In other words, when the determination circuit 701 determines that the rising timings of the output pulse signals of the light receiving elements 313 and 317 are not overlapped, the output pulse signals are input as they are. Combine and output. When the determination circuit 701 determines that the rising timings of the output pulse signals of the light receiving elements 313 and 317 are overlapped, one output pulse signal from the determination circuit 701 is input as it is, and the other output from the determination circuit 701 is input. Is output after being delayed by the delay circuit 702, one of the output pulse signals and the other output pulse signal from the delay circuit 702 are OR-combined and output.

The multiplication circuit 704 is a multiplication means, synchronizes the synthesized signal input from the synthesis circuit 703 with a reference clock from a reference clock generation circuit (not shown), and multiplies it to a half frequency and outputs it.
1 performs feedback control on the control target value based on the output pulse signal from the output synthesis circuit 700 (actually, the count value of the output pulse signal sampled at a predetermined timing), and the drive The drive of the motor 32, that is, the transfer / conveying belt 60 is controlled.

  However, when one of the two light receiving elements 313 and 317 becomes unusable, the output pulse signal of the other light receiving element is output from the output combining circuit 700 as a combined signal. The feedback control is performed using the synthesized signal. At this time, the multiplication circuit 704 does not multiply the synthesized signal by 1/2. Further, when both the light receiving elements 313 and 317 become unusable, the feedback control is stopped. 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”.

  FIG. 10 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 an encoder pulse counter and a control cycle timer counter, which will be described later. Further, the output pulse of the encoder 31 below is actually an output pulse of the output synthesis circuit 700.

  First, in FIG. 10, the count value of the encoder pulse counter that counts the output pulse (encoder pulse) of the encoder 31 is incremented (+1) by the rising edge of the encoder pulse output. 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”. .
Each time the CPU 601 is interrupted by the control cycle timer, the encoder pulse counter count value: ne is acquired and the control cycle timer counter count value: q is acquired and incremented (+1).

Based on these count values, the position deviation is calculated 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 this 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 a sudden position change, it is preferable to perform a filter calculation with the following specifications on 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): 50Hz
Stopband edge frequency (Fs): 100Hz

A block diagram of the filter operation is shown in FIG. 11, 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 operations are performed each time a control timer interrupt is generated 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. 13 shows the amplitude characteristics of this filter, and FIG. 14 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

The 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. 15, when w (n), w (n-1), and w (n-2) are defined as intermediate nodes, the difference equation is as follows (general expression of 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. 15 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 this 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. 16 shows an operation flowchart of the encoder pulse counter described above. In the flowchart of FIG. 16 and the flowchart described below, each step is abbreviated as “S”.
First, it is determined whether or not it is the first pulse input after through-up and settling (S1). If YES, the encoder pulse counter is cleared to zero (S2), the control cycle timer counter is cleared to zero (S3), and the control cycle timer The interrupt 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 encoder pulse counter is incremented (S6), and the process returns to the main routine.

FIG. 17 shows a flowchart of interrupt processing by the control cycle timer.
First, the control cycle timer counter is incremented (S21), and then the encoder pulse count value ne is acquired (S22). Furthermore, the value of Δθ is acquired by referring to the table data (S23), and the table data reference address is incremented (S24). Next, a position deviation calculation is performed using these values (S25), a filter calculation is performed on the obtained position deviation (S26), and a control amount calculation (proportional calculation) is performed based on the result of the filter calculation. (S27). Then, the frequency of the drive pulse of the drive motor 32 (stepping motor) is actually changed (S28), 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.
In the above-described embodiment, the lower right roller 66 among the driven rollers driven to rotate by the rotation of the transfer conveyance belt is the target roller to which the encoder is attached. However, the other driven rollers or the transfer conveyance belt are rotated. The driving roller may be the 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 rollers), any of the belt driving devices Applicable.

In the above-described embodiment, the present invention is applied to a direct transfer type color printer that transports transfer paper by the transfer transport belt 60 and sequentially transfers four color toner images from the photosensitive drum onto the transfer paper. The present invention is also applied to an intermediate transfer belt driving device in an indirect transfer type color printer that transfers four color toner images onto an intermediate transfer belt, transfers the four colors together, and transfers them onto a transfer sheet at once. Is possible.
Furthermore, although laser light is used as the exposure light source in the above-described embodiment, the present invention is not limited to this. 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. FIG. 2 is a block diagram illustrating a configuration example of an output synthesis circuit 700 in FIG. 1. 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 1 step | paragraph filter calculation in FIG. It is an operation | movement flowchart of an encoder pulse counter. 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: Disk 331: Encoder sensor 600: Control unit 601: CPU 602: RAM
603: ROM 604: IO control unit 606: Drive motor IF
607: Driver 608: Detection IO unit 609: Bus 700 Output synthesis circuit 701: Determination circuit 702: Delay circuit 703: Synthesis circuit 704: Multiplication circuit

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 two sensors for detecting the marks or slits, and the sensors are shifted by 180 degrees. It has a configuration attached to
Combining means for combining the output signals of the two sensors;
A multiplying means for multiplying the combined signal from the combining means by 1/2;
Counting means for counting the half multiplied composite signal from the multiplication means;
Sampling means for sampling the count value by the means at a predetermined timing;
A drive control apparatus comprising: feedback control means for driving and controlling the drive roller by performing feedback control on the control target value based on the count value sampled by the sampling means. The drive control device according to claim 1,
A delay means is provided between the two sensors and the combining means;
When the output signals of the two sensors change simultaneously, the delay means delays the output of one of the signals. The drive control apparatus according to claim 1 or 2,
The delay amount of the output of the one signal by the delay means is constant,
The drive control device, wherein the feedback control means includes a filter calculation means. In the drive control device according to any one of claims 1 to 3,
The drive control device, wherein when one of the two sensors becomes unusable, the feedback control means performs the feedback control using only the output signal of the other sensor. In the drive control device according to any one of claims 1 to 4,
The drive control device, wherein the feedback control means stops the feedback control when the two 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.

Images