JP2005157098A - Image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an image forming apparatus capable of shortening an FPOT and suppressing problems of power consumption and vibration small. <P>SOLUTION: The image forming apparatus has a plurality of image carriers 8 to 11, exposure means 16 to 19, a plurality of driving sources 42 and 53 which drive the plurality of image carriers 8 to 11, driving transmitting means 49 to 52 of transmitting driving of the driving sources 42 and 53 to the image carriers 8 to 11, and phase detecting means 56 and 57 of detecting phases of the driving transmitting means 49 to 52, the image forming apparatus being characterized in being equipped with a control means X of calculating the difference between the rotating speed of the driving source 42 of the image carrier 8 being exposed and the rotating speed of the other driving source 53 when at least the one image carrier 8 is exposed by the exposing means 16 based upon detection results of the phase detecting means 56 and 57 and varying the rotating speed of the other driving source 53 according to the rotating speed of the driving source 42 of the image carrier 8 being exposed. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a color image forming apparatus such as a color copying machine or a color printer.

  The conventional color laser printer employs a mechanism called a “four-pass method” that repeats the printing process for four times for each color using a single photoconductor, so it takes four times as long as monochrome printing. .

  On the other hand, there is a so-called “in-line method” color image forming apparatus in which a plurality of photosensitive drums as image carriers are arranged in a line.

  This is because yellow (Y), magenta (M), and cyan (C) are formed by four photosensitive drums arranged along a transfer belt stretched by a plurality of rollers or an electrostatic conveyance belt that conveys a transfer material. The toner image composed of black (Bk) is sequentially transferred to form a color image by superimposing the respective colors, and the time can be greatly reduced.

  However, in the “in-line” color image forming apparatus, each color image is formed by four photosensitive drums, so that colors are superimposed on each photosensitive drum via four conveyance paths for each color. Compared with the “4-pass type” color image forming apparatus having the configuration, a higher accuracy is required for rotational driving of the photosensitive drum.

  In other words, a gear is generally used for driving the photosensitive drum, and rotation irregularity at a low frequency of one rotation component of the gear always occurs. If the four-pass method is used, it is possible to avoid the cumulative pitch error of the gears by combining the reduction ratio of the drive gear train with an integer, and to match the image forming positions of each color. In this case, since the plurality of photosensitive drums are independent, the drive gears are also independent, and it is difficult to avoid the problem as in the above-described four-pass method, and the image quality deteriorates due to color misregistration due to misalignment of the image forming positions of the respective colors. The phenomenon tends to occur.

  Therefore, as a countermeasure against color misregistration, after using the drum driving gear formed from the same mold as the drum driving gear for driving the four photosensitive drums, the four drum driving gears are driven by the four motors, respectively. A rotational speed adjustment method for detecting the phase of the drum driving gear once per rotation, adjusting the rotational speed of each motor based on the result, correcting the phase, and starting image formation (for example, Patent Document 1) Or a drum drive gear formed from the same mold as the drum drive gear that drives the four photosensitive drums, and the gears are connected so that the phase does not shift. One motor drive method has been used in which four drum drive gears are driven to reduce color misregistration.

  These techniques will be briefly described with reference to FIGS.

  6 is a cross-sectional view of a conventional image forming apparatus, which is shown through a laser scanner, FIG. 7 is a diagram illustrating the timing of phase correction and exposure in the conventional example, and FIG. FIG. 4 is a cross-sectional view of a drum driving unit of an example image forming apparatus, which is shown through a laser scanner.

  First, the rotational speed adjusting method will be described with reference to FIGS.

  1 is a paper feed cassette, 2 is a pickup roller, 3 is a feed roller, 4 is a retard roller, and 5 is a pair of registration rollers. The paper feed cassette 1, the pickup roller 2, the feed roller 3, the retard roller 4, and the registration roller pair 5 are installed at the lower part of the apparatus main body.

  6 is a secondary transfer roller, 7 is an intermediate transfer belt, and 8, 9, 10 and 11 are photosensitive drums which are image carriers. The photosensitive drum 8 is an image carrier that forms an image of yellow (Y), the photosensitive drum 9 is magenta (M), the photosensitive drum 10 is cyan (C), and the photosensitive drum 11 is black (Bk), that is, black.

  Reference numerals 12, 13, 14, and 15 denote motors that are drive sources for driving the plurality of photosensitive drums 8 to 11, respectively. The photosensitive drums 8 to 11 are driven by motors 12 to 15, respectively.

  Reference numerals 16, 17, 18, and 19 denote laser scanners that are exposure means for performing exposure on the photosensitive drums 8 to 11, respectively.

  Reference numeral 20 denotes a fixing unit, 21 denotes a pair of paper discharge rollers, and 22 denotes a paper discharge tray. The fixing device 20, the paper discharge roller pair 21, and the paper discharge tray 22 are installed in the upper part of the apparatus main body.

  Reference numerals 23, 24, 25 and 26 denote drum drive gears which are drive transmission means for transmitting the drive of the motors 12 to 15 to the photosensitive drums 8 to 11, and use four gears molded from the same mold. Reference numerals 23M, 24M, 25M, and 26M are markers provided on the drum drive gears 23 to 26, and reference numerals 27, 28, 29, and 30 are photosensors that are phase detection means. The phase can be detected by detecting the markers 23M to 26M with the photo sensors 27 to 30.

  The motors 12 to 15, the drum drive gears 23 to 26, and the photo sensors 27 to 30 constitute a drive unit.

  Hereinafter, the operation will be described in order.

  The paper fed from the paper feed cassette 1 by the pickup roller 2 is separated into one sheet by the feed roller 3 and the retard roller 4 and conveyed to the registration roller pair 5. Here, the paper stops.

  On the other hand, during this time, the phase of the drum drive gears 23 to 26 is corrected in the drive unit.

  The motors 12 to 15 and the intermediate transfer belt 7 are all rotated, the time for the markers 23M to 26M of the drum drive gears 23 to 26 to pass through the photosensors 27 to 30 is measured, and the reference color, for example, Bk to the drum drive gear 26 is measured. The phase shift of each drum drive gear 23 to 25 is detected. The phase difference is corrected by making a difference between the rotational speed of the drum driving gear 26 of the reference color and the rotational speeds of the other drum driving gears 23 to 25 according to the deviation amount. In other words, the drum drive gear whose phase is advanced from the drum drive gear 26 of the reference color has a lower rotational speed, and conversely, the drum drive gear whose phase is being sent is increased, so that the reference color is increased. The phase difference is eliminated by the difference in rotation speed with the drum drive gear 26.

  Then, as shown in FIG. 7, after the timing T1 when the phase of the drum driving gears 23 to 26 is corrected, the photosensitive drums 8 to 11 are exposed by the laser scanners 16 to 19 to form latent images. The latent image is converted into a toner image by the developing device shown in the figure, and transferred onto the intermediate transfer belt 7 so that the toner images of the respective colors overlap. The conveyance of the paper is restarted in accordance with the color toner image on the intermediate transfer belt 7 thus formed. The restarted paper is transferred with a color toner image by the secondary transfer roller 6, fixed with the toner image by the fixing device 20, and discharged onto the paper discharge tray 22 by the paper discharge roller pair 21.

  Next, a one-motor driving method will be described with reference to FIG.

  Reference numeral 31 denotes a motor that is a drive source of the photosensitive drums 8 to 11 that are four image carriers, 32 denotes a drum drive gear that meshes with the gear of the motor 31, and 32P denotes a pulley gear that transmits driving to the drum drive belt 33. The drum driving gear 32 is provided with a pulley gear 32 </ b> P that transmits driving to the drum driving belt 33. Reference numeral 33 denotes a drum drive belt, and 34, 35, 36, and 37 denote drum drive pulley gears. Drive is transmitted from the drum drive belt 33 to drive the photosensitive drums 8 to 11.

  For the drum drive pulley gears 34 to 37, a product formed by the same mold is used, and the drum drive pulley gears 34 to 37 are assembled in advance by shifting the phase by the distance between the photosensitive drums 8 to 11.

Since the four drum drive pulley gears 34 to 37 mesh with the drum drive belt 33, the phase does not shift from the assembled state, and the drum drive gear can always be kept in phase.
JP 2001-305820 A

  However, the above-described conventional example has some problems.

  In the rotational speed adjustment method, the phase is changed by changing the speed of the other drum drive gears 23 to 25 to ± several% with respect to the drum drive gear 26 of the reference color that rotates at a circumferential speed substantially equal to that of the intermediate transfer belt 7. Correct it. The larger the speed change at this time, the shorter the time required for phase correction, but a larger speed difference occurs between the photosensitive drums 8 to 10 and the intermediate transfer belt 7 at the time of correction. End up. Considering the scratches due to this speed difference and the problem of the rubbing memory of the photosensitive drums 8 to 10, there is a limit to increasing the speed change. Therefore, the phase correction requires a certain time or more. Further, since the photosensitive drums 8 to 11 and the intermediate transfer belt 7 are in contact with each other, the speeds of the three photosensitive drums 8 to 10 other than the reference color among the four photosensitive drums 8 to 11 are changed. It is conceivable that the speed of the transfer belt 7 also fluctuates, and stable image formation cannot be started unless the phase correction is completed. Therefore, as shown in FIG. 7, the time (from the time when the user starts the printing operation to the time when the user obtains the printing result of the first sheet) by the time required for phase correction before the start of exposure ( Hereinafter, there is a problem that FPOT (first print out time) becomes long.

  Note that the problem is that the four photosensitive motors are changed to pulse motors, and after the phase is corrected once, the photosensitive drum is not energized even if a method of controlling so as not to cause a phase shift occurs. There is a possibility that the phase is shifted when 8 to 11 are attached and detached, and cannot be completely eliminated. Therefore, in order to supply a high-quality image, a sequence for correcting the phase is essential, and it has been impossible to avoid an increase in the FPOT.

  In the 1-motor drive method, the drum drive pulley gears 34 to 37 do not move out of phase, so that it is possible to shorten the FPOT without requiring a correction operation before the start of printing. However, the four photosensitive drums are driven by one motor. Therefore, a motor capable of generating a high torque is required, and there is a problem that it is not desirable in terms of power consumption and vibration.

  The present invention has been made in view of the above problems, and an object of the present invention is to provide an image forming apparatus capable of shortening the FPOT and minimizing power consumption and vibration problems. There is to do.

  This invention can solve the said subject by providing the following structure.

  (1) A plurality of image carriers, exposure means for exposing the plurality of image carriers, a plurality of drive sources for driving the plurality of image carriers, and driving of the drive sources are transmitted to the image carriers. An image forming apparatus having a drive transmission means for detecting the phase of the drive transmission means, and exposing when at least one of the image carriers is exposed by the exposure means. The difference between the rotational speed of the drive source of the image carrier that is being performed and the rotational speed of the other drive source is calculated based on the detection result of the phase detection means, and the rotational speed of the other drive source is calculated. An image forming apparatus comprising: a control unit that changes in accordance with a rotational speed of a drive source of the image carrier on which the exposure is performed.

  (2) The image forming apparatus according to (1), wherein at least one of the plurality of driving sources drives the plurality of image carriers at the same rotational speed.

  (3) In the image forming apparatus described in the item (2), the plurality of image carriers are three image carriers.

  (4) The image forming apparatus according to (1), wherein the other drive source is a drive source for driving one image carrier.

  (5) In the image forming apparatus described in the item (1) or (4), the other drive source is a drive source for driving an image carrier that forms a black image. apparatus.

  (6) An image forming apparatus having a plurality of image carriers and a plurality of drive sources for driving the image carriers, wherein at least one of the plurality of drive sources is a plurality of image carriers. An image forming apparatus comprising a drive source for driving a body at the same rotational speed.

  According to the present invention, it is possible to provide an image forming apparatus capable of shortening the FPOT and minimizing power consumption and vibration problems.

  Hereinafter, embodiments of an image forming apparatus according to the present invention will be described.

  Since the present embodiment is almost the same as the conventional example except for the photosensitive drum driving unit, the same components are denoted by the same reference numerals and detailed description thereof is omitted.

  FIG. 1 is a diagram illustrating a photosensitive drum driving unit of an image forming apparatus according to a first embodiment of the present invention, which is a diagram illustrating a laser scanner. FIG. 2 is a diagram illustrating the first embodiment of the present invention. FIG. 3 is a diagram illustrating a configuration of a drum driving unit and a control system, and is a diagram illustrating a laser scanner. FIG. 3 is a diagram of the photosensitive drum driving unit viewed from the direction of arrow A in FIG. It is the figure which permeate | transmitted and showed the laser scanner.

  1 to 3, reference numeral 42 denotes a motor which is a drive source for driving the photosensitive drums 8 to 11 which are YMC image carriers. The motor 42 is one of a plurality of drive sources 42 and 53. The motor 42 meshes with the drum drive gear 47 and drives the three photosensitive drums 8 to 10 at the same rotational speed. Reference numeral 47 denotes a drum drive gear for YMC, which includes a pulley gear 47P that transmits the drive to the drum drive belt 48. 47P is a pulley gear, and 48 is a drum drive belt which is a drive transmission auxiliary means for YMC.

  Reference numerals 49, 50, 51 denote drum drive pulley gears which are drive transmission means for transmitting the drive of the YMC motor 42 from the drum drive belt 48 to the photosensitive drums 8-10. 49M, 50M and 51M are markers provided on the drum drive pulley gear 51.

  Reference numeral 52 denotes a drum drive pulley gear which is a drive transmission means for transmitting the drive of the Bk motor 53 from the drum drive belt 55 to the photosensitive drum 11. 52M is a marker provided on the drum drive pulley gear 52 for Bk.

  Reference numeral 53 denotes a motor which is a drive source for driving the photosensitive drum 11 which is a Bk image carrier. The motor 53 is one of the plurality of drive sources 42 and 53. The motor 53 is another drive source that changes the rotation speed by the control means X in accordance with the rotation speed of the motor 42, and is a drive source that drives one photosensitive drum 11.

  The motor 53 is in mesh with a drum drive gear 54, and 54 is a drum drive gear for Bk, and includes a pulley gear 54 </ b> P that transmits driving to the drum drive belt 55 for Bk.

  55 is a drum drive belt which is a drive transmission auxiliary means for Bk.

  Here, the drum drive gear 47 and the drum drive gear 54 are the same gear formed by the same mold. The drum drive belt 48 and the drum drive belt 55 are also the same belt and are in the same stretched state. The drum drive pulley gears 49 to 51 and the drum drive pulley gear 52 are also the same pulley gear formed by the same mold.

  One photosensor 56 is provided for the drum drive gear 47 for YMC and is a phase detection means for detecting the phase of the drum drive pulley gear 51. One photosensor 57 is provided for the drum drive gear 54 for Bk. It is a photosensor that is provided and is a phase detection means for detecting the phase of the drum drive pulley gear 52.

  The phase of the drum drive pulley gear 51 can be detected by detecting the marker 51M with the photo sensor 56 once in one rotation, so that the phase of the drum drive gear 47 and the rotation speed of the motor 42 can be calculated.

  In addition, the phase of the drum drive pulley gear 52 can be detected by detecting the marker 52M with the photo sensor 57 once in one rotation, so that the phase of the drum drive gear 54 and the rotation speed of the motor 53 can be calculated. .

  In the present embodiment, the motors for the photosensitive drums 8 to 11 are divided into two motors, the YMC motor 42 and the Bk motor 53, so that the phases of the drum drive gears 47 and 54 are adjusted to appropriate positions. Phase correction is required.

  Reference numeral 81 denotes a phase difference detection unit, 82 denotes a calculation unit such as a CPU, 83 denotes a motor control unit, and X denotes a control unit.

  The phase difference detection unit 81, the calculation unit 82, and the motor control unit 83 constitute a control means X.

  The control means X is configured such that when at least one photosensitive drum 8 is exposed by the laser scanner 16, the rotational speed of the motor 42 of the photosensitive drum 8 being exposed and the rotational speeds of the other motors 53. The difference is calculated based on the detection results of the photo sensors 56 and 57, and the rotational speeds of the other motors 53 are changed in accordance with the rotational speed of the motor 42 of the photosensitive drum 8 on which exposure is performed.

  Next, the operation and action of phase correction will be described.

  In this embodiment, the YMC photosensitive drums 8 to 10 on the upstream side are driven by a single motor 42, so that the phases of the YMC three-color drum driving pulley gears 49 to 51 are not shifted from each other. Therefore, it is only necessary to consider the shift between the drum drive pulley gears 49 to 51 and the drum drive pulley gear 52 without considering the shift between the drum drive pulley gears 49 to 51.

  First, the motor 42 and the motor 53 are rotated to measure the time required for the marker 51M of the drum drive pulley gear 51 and the marker 52M of the drum drive pulley gear 52 to pass through the photosensors 56 and 57, respectively. A phase difference detector 81 detects the phase shift of the drum drive pulley gear 52.

  Then, the phase difference is corrected by adding a difference of ± several% with respect to the rotational speed (rotation speed) of the motor 42 in accordance with the detected deviation amount.

  At this time, during the phase correction, only the photosensitive drum 11 rotates at a speed other than the reference speed, and the photosensitive drums 8 to 10 other than black rotate at a regular speed. The influence on the intermediate transfer belt 7 is reduced, and there is no fear of speed fluctuation.

  Therefore, as long as the phase correction is completed before the exposure of Bk to the photosensitive drum 11 is started, stable image formation is possible. Exposure to the photosensitive drums 8 to 10 can be performed.

  FIG. 4 shows the phase correction and exposure timing of the present invention.

  It is sufficient that the phase correction is completed before the timing T2 at which the Bk exposure is started, and the YMC exposure can be started during the phase correction, thereby shortening the FPOT.

  Further, since the motor 42 only needs to drive three photosensitive drums instead of four as in the conventional one-motor driving method, high torque is not required as in the conventional one-motor driving method. The power consumption and vibration problems can be kept small.

  Since the second embodiment is almost the same as the conventional example and the first embodiment except for the photosensitive drum driving unit, the same components are denoted by the same reference numerals, and detailed description thereof is omitted.

  FIG. 5 is a view showing a photosensitive drum driving unit of the image forming apparatus according to the second embodiment of the present invention, and is a view through a laser scanner.

  Reference numerals 59, 60 and 61 denote drive idler gears which are drive transmission auxiliary means for YMC, and reference numerals 69 and 70 denote drive idler gears which are drive transmission auxiliary means for Bk.

  A motor 42 which is a drive source of the YMC photosensitive drums 8 to 10 drives the photosensitive drums 8 to 10 via YMC driving idler gears 59 to 61 and YMC drum driving gears 23 to 25.

  A motor 53 as a drive source of the Bk photosensitive drum 11 drives the photosensitive drum 11 via Bk drive idler gears 69 and 70 and a Bk drum drive gear 26.

  Here, the drum drive gears 23 to 25 for YMC and the drum drive gear 26 for Bk are the same gear formed by the same mold. Also, the drive idler gear 59 for YMC and the drive idler gear 69 for Bk are the same gear formed by a mold. The drive idler gears 60 and 61 for YMC and the drive idler gear 70 for Bk are the same gear formed by a mold.

  The YMC drum drive gears 23 to 25 and the Bk drum drive gear 26 are provided with markers 23M, 24M, 25M, and 26M.

  The phase of the drum drive gear 25 can be detected by detecting the marker 25M with the photosensor 56 once per rotation.

  Further, the phase of the drum driving gear 26 can be detected by detecting the marker 26M with the photo sensor 57 once per rotation.

  In the second embodiment, similarly to the first embodiment, the motors for the photosensitive drums 8 to 11 are divided into two motors, that is, a YMC motor 42 and a Bk motor 53. Since phase correction for adjusting the phase of 26 to an appropriate position is necessary, the operation and action of phase correction will be described.

  Similarly to the first embodiment, since the upstream YMC photosensitive drums 8 to 11 are driven by a single motor 42, the phases of the YMC three-color drum driving gears 23 to 25 are not shifted from each other. Absent. Therefore, it is only necessary to consider the shift between the drum drive gears 23 to 25 and the drum drive gear 25 without considering the shift between the drum drive gears 23 to 25.

  First, the motor 42 and the motor 53 are rotated to measure the time required for the marker 25M of the drum drive gear 25 and the marker 26M of the drum drive gear 26 to pass through the photosensors 56 and 57, respectively. The phase shift of the drum drive gear 26 is detected by the phase difference detector 81.

  Then, the phase difference is corrected by adding a difference of ± several% with respect to the rotational speed (rotation speed) of the motor 42 in accordance with the detected deviation amount.

  At this time, during the phase correction, only the photosensitive drum 11 rotates at a speed other than the reference speed, and the photosensitive drums 8 to 10 other than black rotate at a regular speed. The influence on the intermediate transfer belt 7 is reduced, and there is no fear of speed fluctuation.

  Therefore, as long as the phase correction is completed before the exposure of Bk to the photosensitive drum 11 is started, stable image formation is possible. Exposure to the photosensitive drums 8 to 10 can be performed.

  As in FIG. 4, the timing of phase correction and exposure in this embodiment is only required to be completed before the timing T2 at which Bk exposure is started. YMC exposure is performed during phase correction. Can be started, which can shorten the FPOT.

  Further, since the motor 42 only needs to drive three photosensitive drums instead of four as in the conventional one-motor driving method, high torque is not required as in the conventional one-motor driving method. The power consumption and vibration problems can be kept small.

  As described above, according to the present invention, by using a plurality of photosensitive drum driving motors, it is not necessary to use a high torque motor, and the problem of vibration can be reduced. Further, since the image formation can be started while correcting the phase, the time until the end of exposure is shortened, the FPOT can be shortened, and the convenience for the user can be improved.

  In the first and second embodiments, only the example using the YMC motor 42 and the Bk motor 53 has been described. However, the present invention is not limited to this example. For example, the YM motor and the CBk motor are used. A motor may be used, or the number of motors may be three.

FIG. 3 is a diagram illustrating a photosensitive drum driving unit of the image forming apparatus according to the first exemplary embodiment of the present invention, which is illustrated through a laser scanner. FIG. 2 is a diagram illustrating a configuration of a drum driving unit and a control system according to the first embodiment of the present invention, and is a diagram illustrating the laser scanner through the laser scanner. FIG. 2 is a diagram of the photosensitive drum driving unit viewed from the direction of arrow A in FIG. The figure which showed the timing of phase correction and exposure of this invention FIG. 6 is a diagram illustrating a photosensitive drum driving unit of an image forming apparatus according to a second exemplary embodiment of the present invention, which is illustrated through a laser scanner. It is sectional drawing of the image forming apparatus of a prior art example, Comprising: The figure which permeate | transmitted and showed the laser scanner Diagram showing phase correction and exposure timing of the conventional example It is sectional drawing of the drum drive part of the image forming apparatus of a prior art example, Comprising: The figure which penetrated and showed the laser scanner

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Paper feed cassette 2 Pickup roller 3 Feed roller 4 Retard roller 5 Registration roller pair 6 Secondary transfer roller 7 Intermediate transfer belts 8-11 Photosensitive drums 12-15 Motors 16-19 Laser scanner 20 Fixing device 21 Paper discharge roller pair 22 Ejection Paper trays 23 to 26 Drum drive gears 27 to 30 Photosensors 23M to 26M Marker 42 Motor 47 Drum drive gear 47P Pulley gear 48 Drum drive belt 49 to 52 Drum drive pulley gear 53 Motor 54 Drum drive gear 54P Pulley gear 55 Drum drive belts 56 and 57 Photosensors 59-61 Drive idler gears 69, 70 Drive idler gear 81 Phase difference detection unit 82 Calculation unit 83 Motor control unit X Control means

Claims (6)

A plurality of image carriers;
Exposure means for exposing the plurality of image carriers;
A plurality of drive sources for driving the plurality of image carriers;
Drive transmission means for transmitting the drive of the drive source to the image carrier;
Phase detection means for detecting the phase of the drive transmission means;
An image forming apparatus having
When at least one of the image carrier is exposed by the exposure means, the difference between the rotational speed of the drive source of the image carrier being exposed and the rotational speed of the other drive source is calculated as follows: Calculate based on the detection result of the phase detection means,
An image forming apparatus comprising: control means for changing the rotation speed of the other drive source in accordance with the rotation speed of the drive source of the image carrier on which the exposure is performed. The image forming apparatus according to claim 1.
At least one of the plurality of driving sources drives the plurality of image carriers at the same rotational speed. The image forming apparatus according to claim 2.
The image forming apparatus, wherein the plurality of image carriers are three image carriers. The image forming apparatus according to claim 1.
The other driving source is a driving source for driving one image carrier. The image forming apparatus according to claim 1 or 4,
The other drive source is a drive source that drives an image carrier that forms a black image. A plurality of image carriers;
A plurality of drive sources for driving the image carrier;
An image forming apparatus having
At least one of the plurality of drive sources is a drive source that drives the plurality of image carriers at the same rotational speed.

Images