JP2015072326A - Image formation apparatus and position shift correction method for image - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an image formation apparatus that forms an image on an image carrier and a position shift correction method for image such that rotary driving of the image carrier can be precisely controlled and a position shift of the image can be thereby securely reduced.SOLUTION: An image formation apparatus and a position shift correction method for image include: detecting a first compressional wave showing variation in peripheral speed detected by a peripheral speed detection part; controlling rotary driving of an image carrier by a drive part so as to cancel the detected first compressional wave; forming an image pattern on the driving-controlled image carrier and transferring the pattern to a transfer member; detecting a second compressional wave showing a shift of the image pattern on the transfer member detected by an image pattern detection part after the transfer; and controlling the rotary driving of the image carrier by the drive part on the basis of the detected first compressional wave and second compressional wave.

Description

  The present invention relates to an image forming apparatus that forms an image on an image carrier and an image misalignment correction method that corrects image misalignment.

  In an image forming apparatus such as a copying machine, a multifunction peripheral, or a printer, an image (for example, a toner image) is usually formed on an image carrier such as a photosensitive member, and the image formed on the image carrier is transferred to a transfer member. It is supposed to be.

  Specifically, the image carrier is rotated at a predetermined peripheral speed, an image is formed on the image carrier in time by an image forming process such as an electrophotographic method, and the image formed on the image carrier is transferred. Transfer to member. For example, in a color image forming apparatus, images of a plurality of different colors (specifically, black (K), cyan (C), magenta (M), and yellow (Y) color components) corresponding to a plurality of images. It is formed on the image carrier at the same time, and multiple color images respectively formed on a plurality of image carriers are transferred onto a transfer member such as an intermediate transfer member or a recording material (for example, a recording sheet such as recording paper). When the transfer member is an intermediate transfer member, it is further transferred to a recording material.

  In such an image forming apparatus, generally, an image carrier is rotationally driven at a predetermined peripheral speed by a drive unit such as a motor.

  By the way, even if the image carrier is rotationally driven at a predetermined peripheral speed, the image on the image carrier may be displaced from the normal position due to uneven rotation (rotational shake) due to fluctuations in the peripheral speed of the image carrier. . It is important to form an image with high accuracy on the image carrier in order to prevent such image displacement. This is particularly required in a color image forming apparatus for transferring a plurality of color images on a transfer member.

  The cause of uneven rotation of the image carrier is, for example, the dimensional accuracy of a drive transmission unit such as a drive gear that transmits rotational drive from the drive unit to the image carrier (for example, eccentricity of the gear or gear accuracy). One factor and the second factor such as the eccentricity of the image carrier that occurs on the image carrier side (downstream side) than the first factor can be exemplified.

  In this regard, Patent Document 1 discloses an image in which the rotational speed of a motor is controlled by a drive control program provided in advance based on a detection signal from a detection device that detects pressure contact and pressure release operation of a transfer device and / or a cleaning device. A forming apparatus is disclosed. Patent Document 2 discloses an image forming apparatus that measures the distance between position detection pattern images.

JP-A-8-115038 JP 2001-83761 A

  However, in the image forming apparatuses described in Patent Documents 1 and 2, rotation unevenness due to a combination of a first factor such as dimensional accuracy of a member such as a drive transmission unit and a second factor such as eccentricity of the image carrier ( In other words, since the peripheral speed of the image carrier is controlled based on the detection result of relatively large rotation unevenness), it is difficult to accurately control the rotational drive of the image carrier. It is difficult to reliably reduce the deviation.

  Accordingly, the present invention is an image forming apparatus and an image misregistration correction method for forming an image on an image carrier, which can accurately control the rotational drive of the image carrier, thereby An object of the present invention is to provide an image forming apparatus and an image misregistration correction method capable of reliably reducing misregistration.

  In order to solve the above-described problems, the present invention provides the following image forming apparatus and image misregistration correction method.

(1) Image forming apparatus An image carrier that carries an image, a drive unit that rotationally drives the image carrier, a peripheral speed detector that detects a peripheral speed of the image carrier that is rotationally driven by the drive unit, and An image forming apparatus comprising: a transfer member that transfers an image pattern onto the image carrier; and an image pattern detection unit that detects the image pattern on the transfer member. First coarse / dense wave detection means for detecting first coarse / dense wave indicating the detected fluctuation of the peripheral speed, and the image by the drive unit so as to cancel the first coarse / dense wave detected by the first coarse / dense wave detection means. First rotation control means for controlling the rotational drive of the carrier, and image pattern transfer control means for forming the image pattern on the image carrier driven and controlled by the first rotation control means and transferring the image pattern to the transfer member. And the image Second coarse / fine wave detection means for detecting a second coarse / fine wave indicating the deviation of the image pattern on the transfer member, which is transferred by a pattern transfer control means and detected by the image pattern detection unit, and the first coarse / fine wave Second rotation control means for controlling rotational driving of the image carrier by the drive unit based on the first coarse / fine wave detected by the detection means and the second coarse / fine wave detected by the second coarse / fine wave detection means. An image forming apparatus comprising:

(2) Image misregistration correction method An image carrier that carries an image, a drive unit that rotationally drives the image carrier, and a peripheral speed that detects a peripheral speed of the image carrier that is rotationally driven by the drive unit An image misregistration correction method for an image forming apparatus, comprising: a detection unit; a transfer member that transfers an image pattern onto the image carrier; and an image pattern detection unit that detects the image pattern on the transfer member. Then, the first compaction wave indicating the fluctuation of the peripheral speed detected by the peripheral speed detection unit is detected, and the drive unit rotates the image carrier so as to cancel the detected first compaction wave. The image pattern formed on the image carrier that is controlled and driven and transferred to the transfer member is transferred, and the shift of the image pattern on the transfer member that is transferred and detected by the image pattern detection unit is detected. 2nd density shown An image misregistration correction method, comprising: detecting a wave; and controlling rotational driving of the image carrier by the drive unit based on the detected first and second dense waves.

  In the present invention, the image bearing unit includes a drive transmission unit that transmits rotational drive from the drive unit to the image carrier, and the peripheral velocity detection unit is rotationally driven by the drive unit via the drive transmission unit. The drive transmission unit includes a plurality of first drive transmission rotation members provided in the drive unit and a second drive transmission rotation member provided in the image carrier. The drive transmission rotation member is provided, and the value of the peripheral speed ratio between the peripheral speed of the first drive transmission rotation member and the peripheral speed of the second drive transmission rotation member is an integer of 1 or more. .

  In the present invention, the first coarse / fine wave detecting means detects the first coarse / fine wave for a plurality of turns of the image carrier at the peripheral velocity detection unit, and calculates a value of the first coarse / fine wave for the plurality of turns. The second coarse / fine wave detection means detects the second coarse / fine wave for a plurality of turns of the image carrier by the image pattern detection unit. A mode in which the second coarse and dense waves having the values for the plurality of rounds are averaged over one round of the image carrier can be exemplified.

  In the present invention, the peripheral speed detector is a plurality of peripheral speed detectors, and the plurality of peripheral speed detectors can be equally provided along the peripheral direction of the image carrier. .

  In the present invention, when an input operation is accepted, the rotation control of the image carrier by the first rotation control means, following the detection of the first coarse / fine wave by the first coarse / fine wave detection means, the image A mode in which a series of correction operations for forcibly transferring the image pattern onto the transfer member by pattern transfer control means and detecting the second coarse / fine wave by the second coarse / fine wave detection means can be exemplified.

  In the present invention, the first coarse / fine wave detection means detects the first coarse / fine wave every predetermined first period, and the predetermined second period is smaller than the first period. Each time, the rotation control of the image carrier by the first rotation control means, the transfer of the image pattern onto the transfer member by the image pattern transfer control means, and the second by the second density / concentration wave detection means. An example of detecting the density wave is illustrated.

  In the present invention, it is possible to exemplify an aspect in which the second period is a period synchronized with a period for performing other adjustment (for example, adjustment of image forming conditions in process control such as density adjustment).

  In the present invention, the setting of the rotational drive control of the image carrier can be exemplified by a mode performed after the job is completed.

  In the present invention, a first correction for generating a first correction wave for controlling the rotational drive of the image carrier by the drive unit so as to cancel the first coarse / fine wave detected by the first coarse / fine wave detection means. A second correction wave for controlling the rotation driving of the image carrier by the drive unit so as to cancel the second dense wave detected by the wave generation means and the second coarse / fine wave detection means; A correction wave generating unit, and a combined correction for generating a combined correction wave by combining the first correction wave generated by the first correction wave generating unit and the second correction wave generated by the second correction wave generating unit Wave generation means, wherein the second rotation control means uses the combined correction wave generated by the combined correction wave generation means to control the rotation drive of the image carrier by the drive unit. it can.

  In the present invention, at least one of the first correction wave generation means and the second correction wave generation means has a basic amplitude and has a distance of one round on the surface of the image carrier. An example is shown in which a correction wave corresponding to the at least one correction wave generating means is generated by multiplying the basic amplitude of the basic correction wave having a period by a predetermined coefficient and shifting it by a predetermined phase. it can.

  In the present invention, the image forming apparatus includes a plurality of the image carriers, and forms images of a plurality of different colors on the plurality of image carriers corresponding to the respective images at the same time. An example is a color image forming apparatus that transfers the images of the plurality of colors formed on the body in a superimposed manner on a transfer member.

  According to the present invention, there is provided an image forming apparatus for forming an image on an image carrier and an image misregistration correction method, wherein the rotational drive of the image carrier can be controlled with high accuracy. It is possible to provide an image forming apparatus and an image misalignment correction method that can reliably reduce misalignment.

1 is a front view schematically showing an image forming apparatus according to an embodiment of the present invention. FIG. 2 is a system configuration diagram schematically showing a drive transmission system of a drive unit in the image forming apparatus shown in FIG. 1. FIG. 2 is a schematic cross-sectional view of a drive transmission system of a drive unit in the image forming apparatus shown in FIG. 1 as viewed from the side. FIG. 2 is a block diagram schematically showing a system configuration in the image forming apparatus shown in FIG. 1. FIG. 6 is a plan view showing an example in which an image pattern for black, an image pattern for cyan, an image pattern for magenta, and an image pattern for yellow are formed on an intermediate transfer belt. FIG. 4 is a plan view showing a positional relationship between image patterns and image patterns formed at both ends in the width direction of the intermediate transfer belt on the intermediate transfer belt. FIG. 5 is a block diagram schematically showing a control configuration of a control unit in the image forming apparatus shown in FIG. 4. It is explanatory drawing for demonstrating the 1st rough wave which shows the fluctuation | variation of the peripheral speed detected by each peripheral speed sensor for black, cyan, magenta, and yellow. An example of an actual detection distance that is a detection distance actually detected by each detected portion for black, cyan, magenta, and yellow with respect to the number of detection pulses (detection time) of each peripheral speed sensor for black, cyan, magenta, and yellow It is the graph represented with an example of the target detection distance used as a target. 10 is a graph of a first dense wave that represents the deviation between the actual detection distance and the target detection distance shown in FIG. 9. It is a graph which shows an example of the 1st correction wave computed from the 1st density wave. It is a waveform showing a basic correction wave ε having a basic amplitude and a distance of one round of the surface of each of the photosensitive drums for black, cyan, magenta, and yellow as one cycle. It is a graph which shows the result of having detected the rotation nonuniformity of each photosensitive drum for black, cyan, magenta, and yellow after correction | amendment by the 1st factor by each peripheral speed sensor for black, cyan, magenta, and yellow. It is explanatory drawing for demonstrating the 2nd dense wave which shows the fluctuation | variation of the circumferential speed detected with the image pattern sensor. 5 is a graph showing an example of an actual detection distance that is a detection distance actually detected by the image pattern sensor with respect to the number of detection image patterns (detection time) of the image pattern sensor, along with an example of a target detection distance that is a target. FIG. 16 is a graph of a second dense wave representing the deviation between the actual detection distance and the target detection distance shown in FIG. 15. It is a graph which shows an example of the 2nd correction wave computed from the 2nd density wave. It is a graph which shows an example of the synthetic | combination correction wave which synthesize | combined the 1st correction wave and the 2nd correction wave. It is a graph which shows the result of having detected the rotation nonuniformity of each photosensitive drum for black, cyan, magenta, and yellow after the correction by the factor which combined the 1st factor and the 2nd factor with the image pattern sensor. It is a top view which shows the forced correction execution screen displayed on the display part in the operation part shown in FIG. It is a flowchart which shows the flow of an example of the process which forcibly performs a series of correction | amendment operation | movement by a control part. It is a flowchart which shows the flow of an example of the process which performs a periodic 1st correction | amendment operation | movement. It is a flowchart which shows the flow of an example of the process which performs regular 2nd correction | amendment operation | movement.

  Embodiments according to the present invention will be described below with reference to the drawings.

[Image forming apparatus]
FIG. 1 is a front view schematically showing an image forming apparatus 100 according to an embodiment of the present invention.

  The image forming apparatus 100 is a tandem color image forming apparatus, and a plurality of (here, four) photosensitive drums 3a, 3b, 3c, and 3d (an example of an image carrier) arranged in parallel along a predetermined direction. A plurality of different colors (specifically, black (K), cyan (C), magenta (M), yellow (Y) color components) images corresponding to photosensitive drums 3a, 3b, 3c and 3d are formed in synchronization with each other, and images of a plurality of colors formed on the photosensitive drums 3a, 3b, 3c, and 3d are superimposed on an intermediate transfer belt 7 (an example of an intermediate transfer member) that functions as a transfer member. And then transferred onto a recording sheet P (an example of a recording material) that acts as a transfer member.

  The image forming apparatus 100 has a copying function of reading an image of the original G and forming an image on a recording sheet P such as recording paper. The image reading apparatus 200 for reading the image of the original G and an image on the recording sheet P are provided. And an image forming apparatus main body 300 having an image forming unit 330 for forming the image forming apparatus.

  In addition to the image forming unit 330, the image forming apparatus main body 300 includes a sheet supply unit 310, a sheet conveying unit 320, and a sheet discharge unit 340, which are installed horizontally.

  The image data handled in the image forming unit 330 is data corresponding to a color image using each color of black (K), cyan (C), magenta (M), yellow (Y), or a single color (for example, black). This corresponds to the monochrome image used. Therefore, in the image forming unit 330, the photosensitive drums 3a, 3b, 3c, and 3d, the chargers 5a, 5b, 5c, and 5d, the developing devices 2a, 2b, 2c, and 2d (here, the developing unit), and the intermediate transfer unit 6a, 6b, 6c, and 6d (here, intermediate transfer rollers) and drum cleaning devices 4a, 4b, 4c, and 4d are respectively provided to form four types of images corresponding to the respective colors. Four image stations are configured in association with cyan, magenta, and yellow. Among the end codes a to d, the code a is black, the code b is cyan, the code c is magenta d is associated with yellow to form four image stations.

  In the image forming apparatus main body 300, the image forming apparatus 300 rotates the photosensitive drums 3a, 3b, 3c, and 3d while rotating the intermediate transfer belt 7 acting as a transfer member in a predetermined moving direction C, thereby charging the charger 5a. , 5b, 5c, 5d uniformly charge the surface of the photosensitive drums 3a, 3b, 3c, 3d to a predetermined potential, and the photosensitive drums 3a, 3b, 3c by the exposure device 1 (here, LSU: laser scanning unit). , 3d is exposed to form an electrostatic latent image on the surface, and the electrostatic latent images on the surfaces of the photosensitive drums 3a, 3b, 3c, 3d are developed by the developing devices 2a, 2b, 2c, 2d. Thus, toner images are formed on the surfaces of the photosensitive drums 3a, 3b, 3c, and 3d. As a result, toner images of the respective colors are formed on the surfaces of the photosensitive drums 3a, 3b, 3c, and 3d. Thereafter, residual toner on the surfaces of the photosensitive drums 3a, 3b, 3c, and 3d is removed and collected by the drum cleaning devices 4a, 4b, 4c, and 4d.

  Subsequently, in the intermediate transfer device 8, the photosensitive drums 3a, 3b, 3c, and 6d are respectively transferred by the intermediate transfer portions 6a, 6b, 6c, and 6d to which the transfer bias is applied while the intermediate transfer belt 7 is moved in the moving direction C. The toner images of the respective colors formed on the surface 3d are sequentially transferred to the intermediate transfer belt 7 and superimposed to form a color toner image on the intermediate transfer belt 7. As a result, a color toner image is formed on the surface of the intermediate transfer belt 7. Thereafter, the residual toner on the surface of the intermediate transfer belt 7 is removed and collected by the intermediate transfer belt cleaning device 9. In the image forming apparatus 100, the residual toner removed and collected by the drum cleaning devices 4a, 4b, 4c, 4d and the intermediate transfer belt cleaning device 9 is accommodated in a waste toner cartridge (not shown). Yes.

  On the other hand, in the sheet supply unit 310, the recording sheets P stacked on the sheet feed cassette 311 are pulled out from the sheet feed cassette 311 by the sheet supply roller unit 312 and conveyed to the image forming unit 330 through the sheet conveyance path 321 in the sheet conveyance unit 320. To do. The paper feed cassette 311 is an detachable member that can be attached to and detached from the image forming apparatus main body 300, and is an example of a sheet storage unit that stores the recording sheet P.

  The sheet conveyance path 321 is provided with a registration roller 322, each conveyance roller 324, and a discharge roller 325. The registration roller 322 temporarily stops the recording sheet P, aligns the leading end of the recording sheet P, The conveyance of the recording sheet P is started in accordance with the transfer timing of the color toner image in the transfer nip area between the transfer belt 7 and the transfer roller 11a in the secondary transfer device 11. That is, the recording sheet P conveyed from the sheet supply unit 310 to the image forming unit 330 through the sheet conveyance path 321 in the sheet conveyance unit 320 is nipped and conveyed in the transfer nip region between the intermediate transfer belt 7 and the transfer roller 11a. Meanwhile, the color toner image on the surface of the intermediate transfer belt 7 is transferred onto the recording sheet P by the transfer roller 11a to which the transfer bias is applied.

  Then, the recording sheet P is sandwiched between the heating roller 121 and the pressure roller 122 of the fixing device 12 and heated and pressed to fix the color toner image on the recording sheet P, and further toward the sheet discharge unit 340. And is discharged to a discharge tray 341 in the sheet discharge unit 340 via a discharge roller 325.

  When image formation is performed not only on the front surface of the recording sheet P but also on the back surface, the recording sheet P having the toner image fixed on the front surface by the fixing device 12 is directed in the reverse direction toward the reverse path 323 by the discharge roller 325. Then, the recording sheet P is turned upside down by the reversing path 323, and the recording sheet P is guided again to the registration roller 322, and a toner image is formed on the back surface of the recording sheet P in the same manner as the front surface of the recording sheet P. After fixing, the recording sheet P is discharged to a discharge tray 341 in the sheet discharge unit 340.

  In addition, the member of the code | symbol which is not demonstrated among the codes | symbols shown in FIG. 1 is demonstrated later.

[Configuration of drive unit]
In the present embodiment, the image forming apparatus 100 further includes a drive unit 400 (see FIGS. 2 to 4) that rotationally drives the photosensitive drums 3a, 3b, 3c, and 3d.

  FIG. 2 is a system configuration diagram schematically showing a drive transmission system of the drive unit 400 in the image forming apparatus 100 shown in FIG. FIG. 3 is a schematic cross-sectional view of the drive transmission system of the drive unit 400 in the image forming apparatus 100 shown in FIG. FIG. 4 is a block diagram schematically showing a system configuration in the image forming apparatus 100 shown in FIG. The drive transmission system of the drive unit 400 has substantially the same configuration among the four image stations. For this reason, in FIG. 3, the drive transmission system in the four image stations of the drive unit 400 is shown in one drawing.

  The drive unit 400 individually drives the black photosensitive drum 3a, the cyan photosensitive drum 3b, the magenta photosensitive drum 3c, and the yellow photosensitive drum 3d at a predetermined peripheral speed. Here, needless to say, the peripheral speed means the moving speed of the surface of the black photosensitive drum 3a, the cyan photosensitive drum 3b, the magenta photosensitive drum 3c, and the yellow photosensitive drum 3d per unit time. .

  As shown in FIGS. 2 to 4, the driving unit 400 includes a black driving drum 420a, a cyan driving unit 420b, a magenta driving unit 420c, and a yellow driving unit 420d. Rotation driving to the drum 3b, the magenta photosensitive drum 3c, and the yellow photosensitive drum 3d is performed as follows: black drive transmission unit 460a, cyan drive transmission unit 460b, magenta drive transmission unit 460c, and yellow drive transmission unit, respectively. 460d.

  Specifically, the black photosensitive drum 3a is for performing monochrome image formation (monochrome printing), and the cyan photosensitive drum 3b, the magenta photosensitive drum 3c, and the yellow photosensitive drum 3d are In order to form a color image. The images formed on the black photosensitive drum 3a, the cyan photosensitive drum 3b, the magenta photosensitive drum 3c, and the yellow photosensitive drum 3d are superposed on the intermediate transfer belt 7, so that a full-color image is obtained. Can be formed. The diameters of the photosensitive drums 3a, 3b, 3c, and 3d for black, cyan, magenta, and yellow are all the same.

  The driving unit 400 includes a black driving unit 420a, a cyan driving unit 420b, a magenta driving unit 420c, a yellow driving unit 420d, a black driving transmission unit 460a, a cyan driving transmission unit 460b, and a magenta. Drive transmission unit 460c and yellow drive transmission unit 460d. The drive transmission units 460a, 460b, 460c, and 460d for black, cyan, magenta, and yellow can be configured by rotating members such as gears, pulleys, and belts. It consists of multiple gears.

  The black driving unit 420a, the cyan driving unit 420b, the magenta driving unit 420c, and the yellow driving unit 420d are respectively a black photosensitive drum 3a, a cyan photosensitive drum 3b, a magenta photosensitive drum 3c, and a yellow driving unit. This is for driving the photosensitive drum 3d, and in this case, it is a brushless motor.

  The black drive transmission unit 460a, the cyan drive transmission unit 460b, the magenta drive transmission unit 460c, and the yellow drive transmission unit 460d are respectively a black drive unit 420a, a cyan drive unit 420b, a magenta drive unit 420c, and a yellow drive unit. 1st drive transmission rotating member provided in the drive section 420d (here, black shaft gear 461a, cyan shaft gear 461b, magenta shaft gear 461c and yellow shaft gear 461d) (see FIGS. 2 and 3) And a second driving transmission rotating member (here, a black photosensitive drum driving gear 462a) provided on the black photosensitive drum 3a, the cyan photosensitive drum 3b, the magenta photosensitive drum 3c, and the yellow photosensitive drum 3d. Cyan photoconductor drive gear 462b, magenta photoconductor drive gear 462c, and Over photosensitive body drive gear 462d) (includes a plurality of drive transmitting rotary member including at least a see FIGS. 2 and 3).

  The black drive transmission unit 460a transmits rotational drive from the black drive unit 420a to the black photosensitive drum 3a. Here, the black shaft gear 461a and the black photoconductor drive gear 462a are used. It is configured. The cyan drive unit 420b transmits rotational drive from the cyan drive unit 420b to the cyan photoconductor drum 3b. Here, the cyan drive unit 420b includes a cyan shaft gear 461b and a cyan photoconductor drive gear 462b. Has been. The magenta drive transmission unit 460c transmits rotational drive from the magenta drive unit 420c to the magenta photosensitive drum 3c. Here, the magenta shaft gear 461c and the magenta photoconductor drive gear 462c are used. It is configured. The yellow drive transmission unit 460d transmits rotational drive from the yellow drive unit 420d to the yellow photosensitive drum 3d, and here, a yellow shaft gear 461d and a yellow photoconductor drive gear 462d. It is configured. Note that these gears are parallel to each other in the direction of the rotation axis.

  Specifically, the black shaft gear 461a, the cyan shaft gear 461b, the magenta shaft gear 461c, and the yellow shaft gear 461d are respectively a black drive unit 420a, a cyan drive unit 420b, a magenta drive unit 420c, and It is fixed to the rotation shafts 421a, 421b, 421c, and 421d (see FIGS. 2 and 3) of the yellow drive unit 420d. The black photosensitive drum drive gear 462a, the cyan photosensitive drum drive gear 462b, the magenta photosensitive drum drive gear 462c, and the yellow photosensitive drum drive gear 462d are respectively a black photosensitive drum 3a, a cyan photosensitive drum 3b, and a magenta. The photoconductive drum 3c and the yellow photoconductive drum 3d are coaxially connected to the rotation shafts 31a, 31b, 31c, 31d (see FIGS. 2 and 3). The shaft gears 461a, 461b, 461c, and 461d for black, cyan, magenta, and yellow and the shaft gears 461a, 461b, 461c, and 461d for black, cyan, magenta, and yellow mesh with each other. As a result, the black, cyan, magenta, and yellow driving units 420a, 420b, 420c, and 420d are driven to rotate, whereby the black photosensitive member driving gear 462a is driven through the black shaft gear 461a and the black photosensitive member driving gear 462a. The black photosensitive drum 3b connected to the cyan photosensitive drum driving gear 462b is connected to the black photosensitive drum 3a connected to the photosensitive drum driving gear 462b via the cyan shaft gear 461b and the cyan photosensitive drum driving gear 462b. The magenta photosensitive drum 3c connected to the magenta photosensitive member driving gear 462c through the magenta shaft gear 461c and the magenta photosensitive member driving gear 462c, and the yellow shaft gear 461d and the yellow photosensitive member. Via the drive gear 462d, it communicates with the yellow photoreceptor drive gear 462d. Been a yellow photosensitive drum 3d can be rotated, respectively.

  The value of the peripheral speed ratio V1: V2 (for example, V1 / V2 = 2/1) between the peripheral speed of the black shaft gear 461a and the peripheral speed of the black photoconductor drive gear 462a is an integer equal to or greater than 1 (for example, 2). It is. The value of the peripheral speed ratio V1: V2 (for example, V1 / V2 = 2/1) between the peripheral speed of the cyan shaft gear 461b and the peripheral speed of the cyan photoconductor drive gear 462b is an integer of 1 or more (for example, 2). . The value of the peripheral speed ratio V1: V2 (for example, V1 / V2 = 2/1) between the peripheral speed of the magenta shaft gear 461c and the peripheral speed of the magenta photosensitive member drive gear 462c is an integer equal to or greater than 1 (for example, 2). . The value of the peripheral speed ratio V1: V2 (for example, V1 / V2 = 2/1) between the peripheral speed of the yellow shaft gear 461d and the peripheral speed of the yellow photoconductor drive gear 462d is an integer equal to or greater than 1 (for example, 2). It is.

  Specifically, the ratio of the number of teeth (gear ratio) G2: G1 between the number of teeth of the black photoconductor driving gear 462a and the number of teeth of the black shaft gear 461a (for example, G2 / G1 = 2/1) is 1. The above integer (for example, 2). The tooth number ratio (gear ratio) G2: G1 (for example, G2 / G1 = 2/1) between the number of teeth of the cyan photoconductor driving gear 462b and the number of teeth of the cyan shaft gear 461b is an integer of 1 or more (for example, 2). The ratio of the number of teeth (gear ratio) G2: G1 (for example, G2 / G1 = 2/1) between the number of teeth of the magenta photosensitive member driving gear 462c and the number of teeth of the magenta shaft gear 461c is an integer of 1 or more (for example, 2). Further, the ratio of the number of teeth (gear ratio) G2: G1 (for example, G2 / G1 = 2/1) between the number of teeth of the yellow photoconductor driving gear 462d and the number of teeth of the yellow shaft gear 461d is an integer of 1 or more. (For example, 2).

  Note that the reverse ratio, that is, the value of the peripheral speed ratio V2: V1 (specifically, the value of the gear ratio (gear ratio) G1: G2) may be an integer of 1 or more.

  Further, the black driving unit 420a, the cyan driving unit 420b, the magenta driving unit 420c, and the yellow driving unit 420d also drive the developing devices 2a, 2b, 2c, and 2d, respectively.

  Note that the shaft gears 461a, 461b, 461c, and 461d for black, cyan, magenta, and yellow and the photoconductor drive gears 462a, 462b, 462c, and 462d for black, cyan, magenta, and yellow, respectively. An intermediate gear train comprising a single intermediate gear or a plurality of gears is provided, and shaft gears 461a, 461b, 461c, and 461d for black, cyan, magenta, and yellow, and photosensitive materials for black, cyan, magenta, and yellow, respectively. The body drive gears 462a, 462b, 462c, and 462d may mesh with the intermediate gear or the intermediate gear train, respectively. A pulley may be provided in place of the gear, and a belt may be stretched between the pulleys.

[Control system configuration]
As illustrated in FIG. 4, the image forming apparatus 100 further includes a control unit 600 that controls the entire image forming apparatus 100.

  The control unit 600 controls the operation of the drive unit 400. The drive unit 400 further includes a drive control circuit 500 that acts as a drive control unit, a black control circuit 520a, a cyan control circuit 520b, a magenta control circuit 520c, a yellow control circuit 520d, and a belt drive unit. 28.

  The drive control circuit 500 is connected to the control unit 600. Based on the instruction signal from the control unit 600, the drive control circuit 500 converts the speed pulse signal into a black control circuit 520a, a cyan control circuit 520b, a magenta control circuit 520c, and the like. Each drive unit for black, cyan, magenta, and yellow is transmitted to the black drive unit 420a, the cyan drive unit 420b, the magenta drive unit 420c, and the yellow drive unit 420d via the yellow control circuit 520d. Operation control of 420a, 420b, 420c, 420d is performed.

  The black control circuit 520a is connected between the drive control circuit 500 and the black drive unit 420a. The cyan control circuit 520b is connected between the drive control circuit 500 and the cyan drive unit 420b. The magenta control circuit 520c is connected between the drive control circuit 500 and the magenta drive unit 420c. The yellow control circuit 520d is connected between the drive control circuit 500 and the yellow drive unit 420d.

  The drive control circuit 500 has a black drive unit 420a, a cyan drive unit 420b, and a magenta drive unit for the black control circuit 520a, the cyan control circuit 520b, the magenta control circuit 520c, and the yellow control circuit 520d, respectively. Commands for starting, stopping, and driving speed of the drive unit 420c and the yellow drive unit 420d are given.

  The black control circuit 520a, the cyan control circuit 520b, the magenta control circuit 520c, and the yellow control circuit 520d are under the instruction of the drive control circuit 500, respectively, the black drive unit 420a, the cyan drive unit 420b, and the magenta use circuit. The circuit controls the start, stop, and drive speed of the drive unit 420c and the yellow drive unit 420d. Here, the black drive unit 420a, the cyan drive unit 420b, and magenta are set to the target speeds commanded from the drive control circuit 500. The servo drive circuit controls the drive speeds of the driving unit 420c and the yellow driving unit 420d to coincide with each other.

  Further, the drive control circuit 500 sets the black drive unit 420a, cyan drive unit 420b, magenta drive unit 420c, and yellow drive unit 420d at a predetermined process speed (image formation drive speed) during image formation. The black control circuit 520a, the cyan control circuit 520b, the magenta control circuit 520c, and the yellow control circuit 520d are each commanded to be driven.

  The drive units 420a, 420b, 420c, and 420d for black, cyan, magenta, and yellow are respectively photosensitive drums 3a and 3b for black, cyan, magenta, and yellow under the instruction of the drive control circuit 500. , 3c, 3d are controlled to rotate at a predetermined peripheral speed. This rotation control will be described in detail later.

  The belt drive unit 28 is a drive motor that drives the intermediate transfer belt drive roller 21. The belt drive unit 28 rotationally drives the intermediate transfer belt 7 (see FIG. 1) via the intermediate transfer belt drive roller 21. The belt drive unit 28 is controlled to operate under the instruction of the drive control circuit 500, and moves the intermediate transfer belt 7 in a revolving manner at a predetermined peripheral speed.

  The control unit 600 includes an operation unit 115, an image input unit 62, an exposure apparatus 1, and peripheral speed sensors 170a, 170b, 170c, and 170d (an example of a peripheral speed detection unit) for black, cyan, magenta, and yellow, and An image pattern sensor 190 (an example of an image pattern detection unit) is connected.

  The operation unit 115 includes an input unit 116 and a display unit 117. The operation unit 115 is configured to receive various setting information of the entire apparatus and input information for operating each function at the input unit 116, and the input content and the operation status of the entire apparatus are displayed at the display unit 117. It is displayed.

  The image input unit 62 acquires image data of an image to be output from the outside. A source that provides image data is a device connected to the image forming apparatus 100 via a communication line. An example of this device is a host computer such as a personal computer. Another example is an image scanner. The acquired image data is stored in the RAM of the storage unit 620 (see FIG. 7 described later) for printing processing. Information indicating the attribute is given to the image data acquired from the image input unit 62. The assigned attributes include the vertical and horizontal sizes of each image, the type of monochrome image and color image, and the like.

  The exposure apparatus 1 includes a black laser diode 42a, a cyan laser diode 42b, a magenta laser diode 42c, and a yellow laser diode 42d.

  The exposure apparatus 1 receives a signal (pixel signal) based on image data stored in an image memory area in the RAM of the storage unit 620 from an image processing unit (not shown). The image processing unit provides the exposure apparatus 1 with a modulation signal corresponding to each pixel of the image to be processed and output.

  Note that a modulation signal is provided for each color component of black, cyan, magenta, and yellow. The black, cyan, magenta, and yellow modulation signals are used to modulate the light emission of the laser diodes 42a, 42b, 42c, and 42d for black, cyan, magenta, and yellow in the exposure apparatus 1, respectively.

  When forming electrostatic latent images on the photosensitive drums 3a, 3b, 3c, and 3d for black, cyan, magenta, and yellow, the control unit 600 uses a black laser diode 42a and a cyan laser diode for color. The laser diode 42b, the magenta laser diode 42c, and the yellow laser diode 42d emit light, respectively, on the uniformly charged photosensitive drums 3a, 3b, 3c, and 3d for black, cyan, magenta, and yellow, respectively. Control to expose.

[Configuration of peripheral speed sensor]
The image forming apparatus 100 further includes a peripheral speed sensor for black 170a, a peripheral speed sensor for cyan 170b, a peripheral speed sensor for magenta 170c, and a peripheral speed sensor for yellow 170d.

  The peripheral speed sensor for black 170a, the peripheral speed sensor for cyan 170b, the peripheral speed sensor for magenta 170c, and the peripheral speed sensor for yellow 170d are respectively a black photosensitive drum 3a, a cyan photosensitive drum 3b, and a magenta photosensitive drum. The peripheral speed (rotational angular speed) of the photosensitive drum 3d and the yellow photosensitive drum 3d is detected. The peripheral speed can be obtained from the rotational angular speed by the distance (outer peripheral distance) of one surface of the surface of each of the photosensitive drums 3a, 3b, 3c, and 3d for black, cyan, magenta, and yellow.

  In the present embodiment, the image forming apparatus 100 includes the black detected portion 32a detected by the black peripheral speed sensor 170a, the cyan peripheral speed sensor 170b, the magenta peripheral speed sensor 170c, and the yellow peripheral speed sensor 170d. Further, a cyan detected portion 32b, a magenta detected portion 32c, and a yellow detected portion 32d (see FIGS. 2 and 3) are further provided.

  Here, the peripheral speed sensor for black 170a, the peripheral speed sensor for cyan 170b, the peripheral speed sensor for magenta 170c, and the peripheral speed sensor for yellow 170d are all light emitting section 181 (see FIG. 3) and light receiving section 182 (see FIG. 3). ) -Type optical sensor (photo interrupter).

  The black detected portion 32a, the cyan detected portion 32b, the magenta detected portion 32c, and the yellow detected portion 32d are respectively a black photosensitive drum 3a, a cyan photosensitive drum 3b, and a magenta photosensitive drum. 3c and the photosensitive drum 3d for yellow are fixed to the rotation shafts 31a, 31b, 31c and 31d.

  The peripheral speed sensor for black 170a, the peripheral speed sensor for cyan 170b, the peripheral speed sensor for magenta 170c, and the peripheral speed sensor for yellow 170d are respectively a black photosensitive drum 3a, a cyan photosensitive drum 3b, and a magenta photosensitive drum. The black detected portion 32a, the cyan detected portion 32b, the magenta detected portion 32c, and the yellow detected portion 32d, which are rotated by the rotation of the 3c and yellow photosensitive drums 3d, are detected.

  Specifically, the detected portions 32a, 32b, 32c, and 32d for black, cyan, magenta, and yellow are all formed radially and evenly along the circumferential direction on the peripheral portion of the transparent disk. Further, by printing a plurality (for example, 800 to 1000) of light shielding portions SL1 to SL1 (see FIGS. 2 and 3) of opaque (here black), a plurality ( For example, the encoder disk is formed with 800 to 1000 slits SL2 to SL2 (see FIGS. 2 and 3).

  The peripheral speed sensors 170a, 170b, 170c, and 170d for black, cyan, magenta, and yellow convert the incident light that is incident on the light receiving unit 182 from the light emitting unit 181 to the photosensitive drums for black, cyan, magenta, and yellow, respectively. The black, cyan, magenta, and yellow detected portions 32a, 32b, 32c, and 32d are rotated and blocked by the light shielding portions SL1 to SL1 and the slits SL2 to SL2 by the rotation of 3a, 3b, 3c, and 3d. Therefore, the light receiving unit 182 detects the presence or absence of incident light.

  The slits SL <b> 2 to SL <b> 2 may be through holes or uneven portions formed radially and evenly at the outer peripheral edge. Further, the peripheral speed sensors 170a to 170d are reflection type optical sensors, and the light absorbing parts such as black that absorb light are printed on the white disks that reflect light as the detected parts 32a to 32d. Good.

  In this embodiment, as shown in FIGS. 2 and 3, there are a plurality of black peripheral speed sensors 170a, cyan peripheral speed sensors 170b, magenta peripheral speed sensors 170c, and yellow peripheral speed sensors 170d. , Two peripheral speed sensors for black 171a, 172a, a plurality (two in this case) of cyan peripheral speed sensors 171b, 172b, a plurality (here, two) of magenta peripheral speed sensors 171c, 172c, and a plurality ( In this case, two peripheral speed sensors 171d and 172d for yellow are used.

  In the present embodiment, as shown in FIG. 2, a plurality of (here, two) peripheral speed sensors (171a, 172a), (171b, 172b), (171c) for black, cyan, magenta, and yellow. , 172c), (171d, 172d) are equally distributed along the circumferential direction of each of the detected portions 32a, 32b, 32c, 32d for black, cyan, magenta, and yellow (here, black, cyan, magenta, and The yellow detection parts 32a, 32b, 32c, and 32d are provided at positions opposite to each other with the rotation centers therebetween.

[Image pattern sensor configuration]
As shown in FIG. 1, the image forming apparatus 100 further includes an image pattern sensor 190 that detects the image pattern on the intermediate transfer belt 7.

  The intermediate transfer device 8 disposed in the vicinity of the image pattern sensor 190 includes an intermediate transfer belt driving roller 21, a driven roller 22, and a tension roller 23 in addition to the intermediate transfer portions 6a, 6b, 6c, and 6d and the intermediate transfer belt 7. And an intermediate transfer belt cleaning device 9.

  Roller members such as the intermediate transfer belt drive roller 21, the intermediate transfer roller 6, the driven roller 22, and the tension roller 23 stretch and support the intermediate transfer belt 7, and the intermediate transfer belt 7 is moved in a predetermined moving direction (arrow in the figure). Move around in the C direction).

  The image pattern sensor 190 is disposed downstream of the photosensitive drum (here, the black photosensitive drum 3a) in the moving direction C of the endless intermediate transfer belt 7. Specifically, the image pattern sensor 190 is disposed so as to face the surface of the intermediate transfer belt 7.

  Here, the image pattern sensor 190 is a reflection type optical sensor (photo interrupter) having a light emitting unit 191 and a light receiving unit 192. As will be described later, the image pattern sensor 190 detects each image pattern Pa, Pb, Pc, Pd (see FIGS. 5 and 6 described later) (adjustment pattern) formed on the intermediate transfer belt 7. Yes. Specifically, the image pattern sensor 190 detects incident light reflected from the light emitting unit 191 on the surface of the intermediate transfer belt 7 or each image pattern Pa, Pb, Pc, Pd by the light receiving unit 192.

[Image pattern formation]
FIG. 5 is a plan view showing an example in which the black image pattern Pa, the cyan image pattern Pb, the magenta image pattern Pc, and the yellow image pattern Pd are formed on the intermediate transfer belt 7.

  The control unit 600 intermediates the black image pattern Pa (Pa1 to Pan), the cyan image pattern Pb (Pb1 to Pbn), the magenta image pattern Pc (Pc1 to Pcn), and the yellow image pattern Pd (Pd1 to Pdn). It is formed on a transfer belt 7 (an example of a transfer member). However, n is an integer greater than or equal to 2 (here, n = 16).

  That is, the control unit 600 has black, cyan, magenta, and yellow images each having a predetermined width (for example, 3 mm) formed by the photosensitive drums 3a, 3b, 3c, and 3d for black, cyan, magenta, and yellow. Patterns Pa, Pb, Pc, and Pd are formed on the intermediate transfer belt 7 at a predetermined constant pitch θp (for example, 24 mm) in the circumferential direction.

  Specifically, the control unit 600 uses the exposure apparatus 1 on the photosensitive drums 3a, 3b, 3c, and 3d for black, cyan, magenta, and yellow, and the image patterns Pa to Pd for black, cyan, magenta, and yellow. Are formed into toner images by the developing devices 2a, 2b, 2c, and 2d, and the developed toner images are respectively developed for black, cyan, magenta, and yellow. The image patterns Pa to Pd are electrostatically transferred to the intermediate transfer belt 7 by the intermediate transfer portions 6a, 6b, 6c and 6d.

  Specifically, when the control unit 600 forms the image patterns Pa, Pb, Pc, and Pd for black, cyan, magenta, and yellow, black, stored in advance in the storage unit 620 (see FIG. 7). Pattern data of the image patterns Pa, Pb, Pc, and Pd for cyan, magenta, and yellow are acquired. The control unit 600 develops the acquired pattern data in the image memory area and prepares image patterns Pa, Pb, Pc, and Pd for black, cyan, magenta, and yellow. Thereafter, the control unit 600 transfers the developed black, cyan, magenta, and yellow image patterns Pa, Pb, Pc, and Pd to the exposure apparatus 1.

  In the exposure apparatus 1, the cyan, magenta, and yellow laser diodes 42a, 42b, 42c, and 42d that have received the data are the photosensitive drums 3a, 3b, 3c, and 3d for black, cyan, magenta, and yellow, respectively. An electrostatic latent image corresponding to each of the image patterns Pa, Pb, Pc, and Pd for black, cyan, magenta, and yellow is formed thereon.

  The developing devices 2a, 2b, 2c, and 2d develop the electrostatic latent image formed by the exposure device 1 to form toner images of image patterns Pa, Pb, Pc, and Pd for black, cyan, magenta, and yellow. To do. The toner images of the image patterns Pa, Pb, Pc, and Pd for black, cyan, magenta, and yellow are transferred onto the intermediate transfer belt 7 by the intermediate transfer portions 6a, 6b, 6c, and 6d, respectively. Thus, the black image pattern Pa, the cyan image pattern Pb, the magenta image pattern Pc, and the yellow image pattern Pd are formed on the intermediate transfer belt 7.

  The image patterns Pa to Pd for black, cyan, magenta, and yellow are aligned on the intermediate transfer belt 7 in a straight line extending in the width direction (main scanning direction) E of the intermediate transfer belt 7 and in the moving direction C. Are aligned with each other. In the present embodiment, the patterns of different colors are formed at different positions in the moving direction (sub-scanning direction) C of the intermediate transfer belt 7, and the interval between the patterns (distance h, for example, 6 mm, see FIG. 5). ) Is open.

  The patterns are arranged in the same order from the downstream side to the upstream side in the moving direction C of the intermediate transfer belt 7. Here, the cyan image patterns Pb1 to Pbn, the black image patterns Pa1 to Pan, and the magenta images. Patterns Pc1 to Pcn and yellow image patterns Pd1 to Pdn are formed in this order. The image patterns Pa, Pb, Pc, and Pd for black, cyan, magenta, and yellow may be detected at a plurality of locations in the width direction E of the intermediate transfer belt 7. For example, the image patterns Pa, Pb, PC, and Pd for black, cyan, magenta, and yellow may be formed at one end in the width direction E of the intermediate transfer belt 7 or at both ends. Also good.

  6 shows image patterns Pa to Pd formed on both ends of the intermediate transfer belt 7 in the width direction E on the intermediate transfer belt 7 and image pattern sensors 190 (the first image pattern sensor 190a and the second image in the illustrated example). It is a top view which shows the positional relationship with the pattern sensor 190b).

  The image pattern sensor 190 is provided corresponding to the image patterns Pa, Pb, Pc, and Pd for black, cyan, magenta, and yellow formed at different positions in the width direction (main scanning direction) E of the intermediate transfer belt 7. It has been. In the example shown in FIG. 6, the image pattern sensor 190 includes a first image pattern sensor 190a and a second image pattern sensor 190b. A plurality of black, cyan, magenta, and yellow image patterns Pa, Pb, Pc, and Pd in the width direction E on the intermediate transfer belt 7 are disposed so as to face each other. Note that when the black, cyan, magenta, and yellow image patterns Pa, Pb, Pc, and Pd are detected at a plurality of locations in the width direction E of the intermediate transfer belt 7, the values are the values detected at the plurality of locations. An average value can be taken.

  The black, cyan, magenta, and yellow image patterns Pa, Pb, Pc, and Pd formed on the intermediate transfer belt 7 include black, cyan, magenta, and yellow photosensitive drums 3a, 3b, and 3c. , 3d includes a pitch variation component due to a periodic variation of the peripheral speed. If there is a mismatch in this pitch variation, it is recognized as a color shift of the image.

[About the control unit]
FIG. 7 is a block diagram schematically showing a control configuration of the control unit 600 in the image forming apparatus 100 shown in FIG.

  As shown in FIG. 7, the control unit 600 includes a processing unit 610 formed of a microcomputer such as a CPU (Central Processing Unit), a ROM (Read Only Memory), a RAM (Random Access Memory), and a data rewritable nonvolatile memory. And a storage unit 620 including a storage device.

  The control unit 600 controls the operation of various components by causing the processing unit 610 to load and execute a control program stored in advance in the ROM of the storage unit 620 on the RAM of the storage unit 620. Yes. The RAM of the storage unit 620 provides a working work area and an area as an image memory for storing image data to the processing unit 610, respectively.

  Specifically, the control unit 600 stores the acquired image data in the RAM in association with the assigned attribute. The image data is stored in the RAM in units of jobs, and further stored in units of pages when one job consists of a plurality of pages. When the image data is input from an external host in the page description language format, the control unit 600 expands the input image data and stores it in the image memory area. The ROM of the storage unit 620 stores a program that defines a processing procedure executed by the control unit 600, and various data and arithmetic expressions used by the control unit 600.

[Image misalignment correction]
By the way, in the image forming apparatus 100, the rotational drive from the black, cyan, magenta, and yellow driving units 420a, 420b, 420c, and 420d to the photosensitive drums 3a to 3d for black, cyan, magenta, and yellow is transmitted. Dimensional accuracy of drive transmission parts such as drive gears (here, black, cyan, magenta and yellow shaft gears 461a, 461b, 461c, 461d (see FIGS. 2 and 3)) and / or black, cyan, magenta and The first factor such as the eccentricity and gear accuracy of the yellow photoconductor drive gears 462a, 462b, 462c, and 462d (see FIGS. 2 and 3) and the photoconductor drum side (downstream side) than the first factor. The eccentricity of the generated photosensitive drums 3a, 3b, 3c, 3d for black, cyan, magenta and yellow Black due to the second factor that Tsu, cyan, magenta, and the photosensitive drums 3a for yellow, 3b, 3c, rotation unevenness due to variations in the circumferential speed of the 3d may occur.

  For this reason, the control unit 600 controls the operation of the driving unit 400 to correct the rotation unevenness caused by the fluctuations in the peripheral speeds of the photosensitive drums 3a, 3b, 3c, and 3d for black, cyan, magenta, and yellow.

  Specifically, the control unit 600 sets the detection timings of the photosensitive drums 3a, 3b, 3c, and 3d read by the peripheral speed sensors 170a, 170b, 170c, and 170d for black, cyan, magenta, and yellow as normal timings. Compare to find the deviation. Further, the control unit 600 obtains a deviation by comparing the detection timing of each image pattern Pa, Pb, Pc, Pd read by the image pattern sensor 190 with a normal timing.

[First Embodiment]
That is, the image forming apparatus 100 according to the present embodiment has the following control configuration.

  The controller 600 includes a first coarse / fine wave detection means P1, a first rotation control means P2, an image pattern transfer control means P3, a second coarse / fine wave detection means P4, and a second rotation control means P5. Has been.

(First rough dense wave detection means)
The first coarse / fine wave detection means P1 is a first coarse / fine wave αa, αb, αc, αd indicating fluctuations in the peripheral velocity detected by the peripheral velocity sensors 170a, 170b, 170c, 170d for black, cyan, magenta, and yellow. (See FIG. 10) is detected.

  FIG. 8 is an explanatory diagram for explaining a first coarse / fine wave indicating fluctuations in the peripheral speed detected by the peripheral speed sensors 170a, 170b, 170c, and 170d for black, cyan, magenta, and yellow. In FIG. 8, the upper waveform shows actual detection pulse signals Sa, Sb, Sc, which are detection pulse signals for black, cyan, magenta, and yellow actually detected by the peripheral speed sensors 170a, 170b, 170c, 170d. It is an example of the waveform of Sd, and the lower waveform is an example of the waveform of the target pulse signal Ts, which is a target (ideal) pulse signal for black, cyan, magenta, and yellow.

  FIG. 9 shows detected portions 32a, 32b, black, cyan, magenta, and yellow for black, cyan, magenta, and yellow with respect to the number of detection pulses (detection time) of each peripheral speed sensor 170a, 170b, 170c, 170d. It is the graph which represented an example of the actual detection distance which is the detection distance actually detected by 32c, 32d with an example of the target detection distance used as a target. FIG. 10 is a graph of the first dense waves αa, αb, αc, αd representing the deviation between the actual detection distance and the target detection distance shown in FIG.

  8, 9, and 10, the symbols corresponding to black, cyan, magenta, and yellow are given, but actually the waveforms are different from each other. In FIGS. 8, 9 and 10, one of black, cyan, magenta and yellow (here, black) is representatively shown. This also applies to FIGS. 11 and 13 to 19 described later.

  As shown in FIG. 8, if there is rotation unevenness due to the first factor, each of the photosensitive drums 3a, 3b, 3c, and 3d for black, cyan, magenta, and yellow is actually detected for black, cyan, magenta, and yellow. In the pulse signals Sa, Sb, Sc, Sd, a wide pitch portion (coarse) and a narrow portion (fine) are periodically generated.

   Such rotation unevenness can be represented by deviations of the actual detection pulse signals Sa, Sb, Sc, and Sd for black, cyan, magenta, and yellow with respect to the target pulse signal Ts for black, cyan, magenta, and yellow.

  As shown in FIG. 9, when the deviation between the actual detection distance and the target detection distance is taken, as shown in FIG. 10, the peripheral speed sensors 170a, 170b, 170c, and 170d for black, cyan, magenta, and yellow are used. It is possible to obtain the first dense waves αa, αb, αc, αd indicating the fluctuations in the peripheral speeds of the detected cyan, magenta, and yellow photosensitive drums 3a, 3b, 3c, 3d. That is, the first dense waves αa, αb, αc, αd can be expressed as deviations of the actual detection distance from the target detection distance for each detection pulse for black, cyan, magenta, and yellow. The first dense waves αa, αb, αc, and αd are each one of the photosensitive drums 3a, 3b, 3c, and 3d for black, cyan, magenta, and yellow for each detection pulse for black, cyan, magenta, and yellow. It is recorded in the non-volatile memory of the storage unit 620 as circumference data.

  In the present embodiment, the first coarse / fine wave detecting means P1 uses the peripheral speed sensors 170a, 170b, 170c, and 170d for black, cyan, magenta, and yellow, and the photosensitive drums for black, cyan, magenta, and yellow. The first coarse and dense waves αa, αb, αc, αd of a plurality of rounds 3a, 3b, 3c, 3d (three rounds in this example) are detected, and the first number of the detected rounds (three rounds in this example) is detected. The values of one coarse / fine wave αa, αb, αc, αd are averaged over one round, and the average of the first black, cyan, magenta, and yellow photosensitive drums 3a, 3b, 3c, 3d for the first round. The values of the dense waves αa, αb, αc, αd are recorded in the nonvolatile memory of the storage unit 620.

(First rotation control means)
The first rotation control means P2 drives each of black, cyan, magenta, and yellow so as to cancel the first coarse / fine waves αa, αb, αc, and αd (see FIG. 10) detected by the first coarse / fine wave detection means P1. The rotation driving of the photosensitive drums 3a, 3b, 3c, and 3d for black, cyan, magenta, and yellow by the units 420a, 420b, 420c, and 420d is controlled.

  Specifically, the first rotation control means P2 performs black, cyan, and magenta corresponding to the dense waves in which the signs of the first dense waves αa, αb, αc, and αd shown in FIG. For black, cyan, magenta, and yellow by the driving units 420a, 420b, 420c, and 420d for black, cyan, magenta, and yellow so that the peripheral speeds of the photosensitive drums 3a, 3b, 3c, and 3d for yellow are obtained. The rotational drive of each of the photosensitive drums 3a, 3b, 3c, 3d is controlled.

  Here, the first dense waves αa, αb, αc, and αd each have a period corresponding to one cycle of the surface of the photosensitive drums 3a, 3b, 3c, and 3d for black, cyan, magenta, and yellow, respectively. It can be regarded approximately as a sine curve or a cosine curve (in this example, a sine curve).

  From this point of view, the control unit 600 is configured to further include first correction wave generation means P6.

  The first correction wave generating means P6 has black, cyan, magenta and yellow driving sections 420a and 420b so as to cancel the first coarse and dense waves αa, αb, αc and αd detected by the first coarse and dense wave detection means P1. , 420c, 420d generate first correction waves α1a, α1b, α1c, α1d for controlling the rotational driving of the photosensitive drums 3a, 3b, 3c, 3d for black, cyan, magenta, and yellow (FIG. 11). The first correction waves α1a, α1b, α1c, α1d for one rotation of the generated photosensitive drums 3a, 3b, 3c, 3d for black, cyan, magenta, and yellow are stored in the nonvolatile memory of the storage unit 620. Record.

  FIG. 11 is a graph showing an example of the first correction waves α1a, α1b, α1c, and α1d calculated from the first dense waves αa, αb, αc, and αd.

  The first correction waves α1a, α1b, α1c, and α1d shown in FIG. 11 are the maximum value (here, about 60 μm) or the minimum value (here, about −) of the first dense waves αa, αb, αc, αd (see FIG. 10). 65 μm) from the amplitude corresponding to the peripheral speed of each of the photosensitive drums 3a, 3b, 3c, and 3d for black, cyan, magenta, and yellow, and the number of detected pulses of the first dense waves αa, αb, αc, and αd, respectively. The sine curve or cosine curve (in this example, sine curve) expressed approximately with the phase corresponding to the number of correction pulses for black, cyan, magenta, and yellow is reversed (inverted upside down). is there.

  Here, each of the first correction waves α1a, α1b, α1c, and α1d may be a peripheral speed value for each of a plurality of (for example, 800 to 1000) correction pulses, but in this example, black, cyan In consideration of shortening the time for controlling each of the driving units 420a, 420b, 420c, and 420d for magenta and yellow, a plurality of (for example, 800 to 1000) correction pulses are set to a predetermined number (for example, 800 to 1000). Here, the peripheral speed value is set for each of a plurality of (for example, 200 to 250) correction blocks divided into four correction pulses. That is, the correction pulses (four consecutive correction pulses here) in the same correction block have the same peripheral speed value.

  The first correction wave generating means P6 has a basic amplitude in consideration of the control configuration for calculating the first correction waves α1a, α1b, α1c, α1d, and each of black, cyan, magenta, and yellow The basic amplitude of the basic correction wave ε (see FIG. 12) with the distance of one circumference of the surface of the photosensitive drums 3a, 3b, 3c, 3d as one cycle is changed to the amplitudes of the first dense waves αa, αb, αc, αd. The first correction waves α1a, α1b, α1c, and α1d are generated by multiplying the corresponding predetermined coefficients and shifting by a predetermined phase corresponding to the phases of the first dense waves αa, αb, αc, and αd. ing.

  FIG. 12 shows a waveform indicating a basic correction wave ε having a basic amplitude and having a period of one cycle on the surface of each of the photosensitive drums 3a, 3b, 3c, and 3d for black, cyan, magenta, and yellow. It is.

  As shown in FIG. 12, the basic correction wave ε has a basic basic amplitude, and shows a sine curve or cosine curve (in this example, a sine curve) indicating fast and slow repetition around the target peripheral speed. Curve) and the peripheral speed for each correction block. Here, the basic correction wave ε is recorded in advance in the nonvolatile memory of the storage unit 620.

  In this example, the first correction waves α1a, α1b, α1c, and α1d multiply the basic amplitude of the basic correction wave ε by about 3 and set the phase of the basic correction wave ε to about ¼ period (for example, about 50 to 63 blocks). ) Delayed (shifted to the right in the figure).

  The first rotation control means P2 is a speed at which the peripheral speeds of the photosensitive drums 3a, 3b, 3c, and 3d for black, cyan, magenta, and yellow become the first correction waves α1a, α1b, α1c, and α1d. By transmitting the pulse signal to the driving units 420a, 420b, 420c, and 420d (see FIG. 4) for black, cyan, magenta, and yellow, the driving units 420a, 420b, black, cyan, magenta, and yellow, respectively. Operation control of 420c and 420d is performed.

  FIG. 13 shows rotational irregularities of the photosensitive drums 3a, 3b, 3c, and 3d for black, cyan, magenta, and yellow after correction due to the first factor, and peripheral speed sensors 170a, black, cyan, magenta, and yellow. It is a graph which shows the result detected by 170b, 170c, 170d.

  As shown in FIG. 13, the control unit 600 can perform a reduction process for reducing the rotation unevenness due to the first factor by the first rotation control means P2.

(Image pattern transfer control means)
The image pattern transfer control means P3 is controlled by the first rotation control means P2 (the reduction process for reducing the rotation unevenness due to the first factor is performed), and each of the photosensitive elements for black, cyan, magenta, and yellow Image patterns Pa, Pb, Pc, Pd are formed on the body drums 3a, 3b, 3c, 3d and transferred to the intermediate transfer belt 7 (see FIGS. 5 and 6).
(Second coarse wave detection means)
The second coarse / fine wave detection means P4 is a second signal indicating the deviation of the image patterns Pa, Pb, Pc, Pd on the intermediate transfer belt 7 transferred by the image pattern transfer control means P3 and detected by the image pattern sensor 190, respectively. The dense waves βa, βb, βc, βd are detected.

  FIG. 14 is an explanatory diagram for explaining second dense waves βa, βb, βc, and βd that indicate fluctuations in the peripheral speed detected by the image pattern sensor 190. In FIG. 14, the upper waveform is an example of the waveforms of actual detected image pattern signals Qa, Qb, Qc, and Qd that are detected image pattern signals for black, cyan, magenta, and yellow actually detected by the image pattern sensor 190. The lower waveform is an example of the waveform of the target image pattern signal Rs, which is a target (ideal) image pattern signal for black, cyan, magenta, and yellow.

  FIG. 15 is a graph showing an example of an actual detection distance, which is a detection distance actually detected by the image pattern sensor 190 with respect to the number of detection image patterns (detection time) of the image pattern sensor 190, along with an example of a target detection distance. is there. FIG. 16 is a graph of the second coarse / dense waves βa, βb, βc, βd representing the deviation between the actual detection distance and the target detection distance shown in FIG.

  As shown in FIG. 14, each of the photosensitive drums 3a, 3b, 3c, and 3d for black, cyan, magenta, and yellow is black when there is rotation unevenness due to a combination of the first factor and the second factor. In the actual detection image pattern signals Qa, Qb, Qc, and Qd for cyan, magenta, and yellow, a wide pitch portion (coarse) and a narrow pitch portion (fine) are periodically generated.

   Such rotation unevenness can be represented by deviations of the actual detected image pattern signals Qa, Qb, Qc, and Qd for black, cyan, magenta, and yellow with respect to the target image pattern signal Rs for black, cyan, magenta, and yellow.

  As shown in FIG. 15, when the deviation between the actual detection distance and the target detection distance is taken, as shown in FIG. 16, the photosensitive drums 3a and 3b for cyan, magenta and yellow detected by the image pattern sensor 190 are obtained. , 3c, 3d can be obtained second coarse and dense waves βa, βb, βc, βd. That is, the second dense waves βa, βb, βc, and βd can be expressed as deviations of the actual detection distance from the target detection distance for each detection image pattern for black, cyan, magenta, and yellow. The second dense waves βa, βb, βc, and βd are respectively detected by the photosensitive drums 3a, 3b, 3c, and 3d for black, cyan, magenta, and yellow for each detected image pattern for black, cyan, magenta, and yellow. The data for one round is recorded in the nonvolatile memory of the storage unit 620.

  In the present embodiment, the second coarse / fine wave detecting means P4 uses the image pattern sensor 190 for a plurality of circumferences of the photosensitive drums 3a, 3b, 3c, and 3d for black, cyan, magenta, and yellow (in this example, 3 Second coarse and dense waves βa, βb, βc, and βd are detected, and the values of the detected second coarse and dense waves βa, βb, βc, and βd for a plurality of rounds (in this example, three rounds) And the average values of the second coarse and dense waves βa, βb, βc, βd for one round of the respective photosensitive drums 3a, 3b, 3c, 3d for black, cyan, magenta, and yellow are stored in the storage unit 620. Record in non-volatile memory.

(Second rotation control means)
The second rotation control means P5 includes first coarse / fine waves αa, αb, αc, αd (see FIG. 10) detected by the first coarse / fine wave detection means P1 and second coarse / fine waves detected by the second coarse / fine wave detection means P4. Based on the waves βa, βb, βc, βd (see FIG. 16), the photosensitive drums 3a for black, cyan, magenta, and yellow by the driving units 420a, 420b, 420c, 420d for black, cyan, magenta, and yellow, respectively. , 3b, 3c, 3d are controlled.

  Specifically, the first rotation control means P2 has a dense wave in which the signs of the first coarse / fine waves αa, αb, αc, and αd shown in FIG. 10 are reversed (inverted up and down) and a second coarse / fine wave shown in FIG. Each of the photosensitive drums 3a, 3b, black, cyan, magenta, and yellow corresponding to the coarse and dense waves obtained by synthesizing the coarse and dense waves obtained by reversing the signs of the waves βa, βb, βc, and βd (inverted upside down) The photosensitive drums 3a, 3b, 3c, and 3d for black, cyan, magenta, and yellow by the driving units 420a, 420b, 420c, and 420d for black, cyan, magenta, and yellow so that the peripheral speeds are 3c and 3d. Controls the rotational drive of.

  Here, the second dense waves βa, βb, βc, and βd are similar to the first coarse waves αa, αb, αc, and αd, respectively, and the photosensitive drums 3a, 3b, and 3c for black, cyan, magenta, and yellow, respectively. , 3d can be regarded approximately as a sine curve or a cosine curve (in this example, a sine curve) with the distance in one round of the surface of 3d as one period.

  From this point of view, the controller 600 is configured to further include second correction wave generation means P7 and combined correction wave generation means P8.

  The second correction wave generating means P7 drives the black, cyan, magenta and yellow driving sections 420a and 420b so as to cancel the second coarse and dense waves βa, βb, βc and βd detected by the second coarse and dense wave detection means P4. , 420c, 420d generate second correction waves β1a, β1b, β1c, β1d for controlling the rotational driving of the photosensitive drums 3a, 3b, 3c, 3d for black, cyan, magenta, and yellow (FIG. 17). The generated second correction waves β1a, β1b, β1c, and β1d for one rotation of the generated photosensitive drums 3a, 3b, 3c, and 3d for black, cyan, magenta, and yellow are stored in the nonvolatile memory of the storage unit 620. Record.

  FIG. 17 is a graph illustrating an example of the second correction waves β1a, β1b, β1c, and β1d calculated from the second coarse and dense waves βa, βb, βc, and βd.

  The second correction waves β1a, β1b, β1c, β1d shown in FIG. 17 are the maximum value (here, about 40 μm) or the minimum value (here, about −2) of the second rough waves βa, βb, βc, βd (see FIG. 16). 30 μm) from the amplitude corresponding to the peripheral speed of each of the photosensitive drums 3a, 3b, 3c, and 3d for black, cyan, magenta, and yellow, and the number of detected image patterns of the second dense waves βa, βb, βc, and βd. The sign of a sine curve or cosine curve (in this example, a sine curve) approximately represented by the phase corresponding to the number of correction image patterns for black, cyan, magenta, and yellow, respectively, was reversed (inverted upside down) Is.

  Here, the second correction wave generating means P7 takes the control amplitude for calculating the second correction waves β1a, β1b, β1c, β1d into the second amplitude of the basic correction wave ε (see FIG. 12). The second correction wave β1a is obtained by multiplying a predetermined coefficient according to the amplitude of the coarse / fine waves βa, βb, βc, βd and shifting by a predetermined phase according to the phases of the second coarse / fine waves βa, βb, βc, βd. , Β1b, β1c, and β1d.

  In this example, the second correction waves β1a, β1b, β1c, and β1d multiply the basic amplitude of the basic correction wave ε by about 2 and set the phase of the basic correction wave ε to about 1/3 period (for example, about 67 to 83 blocks). ) Delayed (shifted to the right in the figure).

  The combined correction wave generation means P8 includes first correction waves α1a, α1b, α1c, α1d generated by the first correction wave generation means P6 and second correction waves β1a, β1b generated by the second correction wave generation means P7. Composite correction waves γa, γb, γc, and γd are generated by combining β1c and β1d (see FIG. 18), and one round of each of the generated photosensitive drums 3a, 3b, 3c, and 3d for black, cyan, magenta, and yellow is generated. Minutes of combined correction waves γa, γb, γc, and γd are recorded in the nonvolatile memory of the storage unit 620.

  FIG. 18 is a graph showing an example of the combined correction waves γa, γb, γc, γd obtained by combining the first correction waves α1a, α1b, α1c, α1d and the second correction waves β1a, β1b, β1c, β1d.

  The combined correction wave generation means P8 adds the first correction waves α1a, α1b, α1c, α1d and the second correction waves β1a, β1b, β1c, β1d, thereby generating the combined correction waves γa, γb, γc shown in FIG. , Γd is generated.

  Then, the second rotation control means P5 generates combined correction waves γa and γb generated by the combined correction wave generating means P8 with the peripheral speeds of the photosensitive drums 3a, 3b, 3c, and 3d for black, cyan, magenta, and yellow. , Γc, γd are transmitted to the drive units 420a, 420b, 420c, 420d (see FIG. 4) for black, cyan, magenta, and yellow, respectively, so that black, cyan, magenta, and yellow are transmitted. Operation control of each drive part 420a, 420b, 420c, 420d for operation is performed.

  FIG. 19 shows the image pattern sensor 190 indicating the rotation unevenness of the photosensitive drums 3a, 3b, 3c, and 3d for black, cyan, magenta, and yellow after correction based on a combination of the first factor and the second factor. It is a graph which shows the detected result.

  As shown in FIG. 19, the control unit 600 uses the second rotation control means P5 to rotate the first factor that has been subjected to the reduction process for reducing the rotation unevenness due to the first factor, and the factor that combines the second factor. The peripheral speeds of the photosensitive drums 3a, 3b, 3c, and 3d for black, cyan, magenta, and yellow can be controlled based on the detection result of unevenness.

  In the present embodiment, a plurality of first coarse / fine waves αa, αb, αc, αd and a plurality of second coarse / fine waves βa, βb, βc, βd are generated by the first coarse / fine wave detection means P1 and the second coarse / fine wave detection means P4. The circumferences are detected, and the values of the detected first coarse / fine waves αa, αb, αc, αd and the second coarse / fine waves βa, βb, βc, βd are averaged over one round. You may make it average the value of the density wave corresponding to it by a wave detection means.

  Further, in the present embodiment, the first correction wave generation unit P6 and the second correction wave generation unit P7 multiply the basic amplitude of the basic correction wave ε by a predetermined coefficient and shift it by a predetermined phase. The correction waves α1a, α1b, α1c, α1d and the second correction waves β1a, β1b, β1c, β1d are generated, but either one of the first correction wave generation means P6 and the second correction wave generation means P7 Corresponding correction waves may be generated.

[Second Embodiment]
When receiving the input operation, the controller 600 detects black, cyan, magenta by the first rotation control means P2 following the detection of the first coarse / fine waves αa, αb, αc, αd by the first coarse / fine wave detection means P1. And rotation control of the photosensitive drums 3a, 3b, 3c, 3d for yellow, transfer of the image patterns Pa, Pb, Pc, Pd onto the intermediate transfer belt 7 by the image pattern transfer control means P3, second density It is configured to forcibly execute a series of correction operations for detecting the second coarse / fine waves βa, βb, βc, βd by the wave detecting means P4.

  Specifically, the configuration for accepting an input operation is realized by inputting a forcible correction execution signal for forcibly executing a series of correction operations to the processing unit 610 (see FIG. 7) of the control unit 600.

  20 is a plan view showing a compulsory correction execution screen displayed on the display unit 117 in the operation unit 115 shown in FIG.

  Here, the operation unit 115 is an operation panel provided in the upper front portion of the exterior cover of the image forming apparatus 100. The operation unit 115 is configured to receive various setting information of the entire apparatus and information for operating each function at the input unit 116. In addition, the operation unit 115 is configured to display the input content and the operation status of the entire apparatus on the display unit 117. Here, the input unit 116 has a plurality of input keys 116a and is a key input operation unit that can be operated by the user.

  The forcible correction execution signal is a signal indicating that a series of correction operations is forcibly executed. Here, as shown in FIG. 20, the simulation mode is set by an input operation of the input key 116a provided in the operation unit 115. In the state shifted to, it is transmitted to the processing unit 610 of the control unit 600 in accordance with the operator's instruction.

  That is, on the compulsory correction execution screen displayed on the display unit 117, the first display button BT1 for transmitting a compulsory correction execution signal for forcibly executing a series of correction operations to the processing unit 610, or a series of correction operations. Is not forcibly executed, and the second display button BT2 that does not transmit the forcible correction execution signal to the processing unit 610 is selected by a touch selection operation on the screen. FIG. 20 shows a state where the first display button BT1 is selected. In the case of forcibly executing a series of correction operations, the execution key EXE is operated when the first display button BT1 is in the reverse display state and the forcible correction execution signal is transmitted to the processing unit 610. To forcibly execute a series of correction operations and return to the previous screen. When a series of correction operations are not forcibly executed, the screen returns to the previous screen by a touch selection operation on the screen of the second display button BT2.

   Note that the forced correction execution screen illustrated in FIG. 20 is used in the production process, for example, during maintenance work by a service person, but is not limited thereto.

  FIG. 21 is a flowchart illustrating an exemplary flow of a process for forcibly executing a series of correction operations by the control unit 600.

  In the processing example of the compulsory correction operation shown in FIG. 21, when the operator selects the first display button BT1 and operates the execution key EXE (see FIG. 20), the control unit 600 accepts an input operation (step S10) First, the photosensitive drums 3a for black, cyan, magenta and yellow are detected by the peripheral speed sensors 170a, 170b, 170c and 170d for black, cyan, magenta and yellow by the first coarse / fine wave detecting means P1. , 3b, 3c, and 3d (step S11), and the first correction wave generation means P6 uses the first correction waves α1a, αb, αc, αd (see FIG. 10) from the first correction waves α1a, α1b, α1c, α1d (see FIG. 11) are respectively calculated (step S12).

  Next, the control unit 600 uses the first rotation control unit P2 to convert the speed pulse signals based on the first correction waves α1a, α1b, α1c, and α1d to the driving units 420a, 420b, and 420c for black, cyan, magenta, and yellow. , 420d, and controls the rotational driving of the photosensitive drums 3a, 3b, 3c, 3d for black, cyan, magenta, and yellow by the driving units 420a, 420b, 420c, 420d, respectively (step S13). In the state in which the rotation unevenness of the photosensitive drums 3a, 3b, 3c, 3d due to the first factor is suppressed (see FIG. 13), black, cyan, magenta, and magenta on the intermediate transfer belt 7 by the image pattern transfer control means P3. The yellow image patterns Pa, Pb, Pc, Pd (see FIGS. 5 and 6) are transferred (steps). S14).

  Next, the control unit 600 uses the second coarse / fine wave detection means P4 to detect the black, cyan, magenta, and yellow image patterns Pa, Pb, Pc, and Pd on the intermediate transfer belt 7 by the image pattern sensor 190. The two coarse / fine waves βa, βb, βc, βd (see FIG. 16) are read (step S15), and the second correction waves β1a, β1b, β1c, β1d (see FIG. 17) are respectively obtained by the second correction wave generating means P7. Calculation is performed (step S16).

  Next, the control unit 600 combines the first correction waves α1a, α1b, α1c, α1d and the second correction waves β1a, β1b, β1c, β1d by the combined correction wave generation means P8, and combines the corrected waves γa, γb, γc and γd (see FIG. 18) are respectively generated (step S17), and the combined correction waves γa, γb, γc, and γd are stored (set) in the nonvolatile memory of the storage unit 620 (step S18). Then, at the time of the next and subsequent jobs, the second rotation control means P5 converts the speed pulse signals based on the combined correction waves γa, γb, γc, and γd in the storage unit 620 to the driving units for black, cyan, magenta, and yellow. 420a, 420b, 420c, and 420d are respectively input to control the rotational driving of the photosensitive drums 3a, 3b, 3c, and 3d for black, cyan, magenta, and yellow by the driving units 420a, 420b, 420c, and 420d, respectively. The correction control to be reflected is reflected. By doing this, each of the black, cyan, magenta, and yellow colors is detected based on the detection result of the rotation unevenness due to the combination of the first factor and the second factor that have been reduced to reduce the rotation unevenness due to the first factor. The peripheral speed of the photosensitive drums 3a, 3b, 3c, 3d can be controlled (see FIG. 19).

[Third Embodiment]
The control unit 600 performs the first coarse / fine wave αa, αb by the first coarse / fine wave detection means P1 every predetermined first period ta (for example, a predetermined time or a predetermined image formation count, in this case, four hours). , Αc, αd, and a predetermined second period tb (<ta) that is smaller than the first period ta (for example, a predetermined time or a predetermined image formation count). , Here every hour), the rotation control of the photosensitive drums 3a, 3b, 3c, 3d for black, cyan, magenta and yellow by the first rotation control means P2, and the image by the image pattern transfer control means P3 A configuration for executing the second correction operation for transferring the patterns Pa, Pb, Pc, Pd onto the intermediate transfer belt 7 and detecting the second coarse / fine waves βa, βb, βc, βd by the second coarse / fine wave detection means P4; Has been .

  The first period and the second period may be common (identical) periods between at least two of the cyan, magenta, and yellow photosensitive drums 3a, 3b, 3c, and 3d. The periods may be different from each other.

  Specifically, the configuration in which the first correction operation is executed in the first period ta and the second correction operation is executed in every second period tb is such that the control unit 600 starts up the power after the job is finished. This is realized by automatically judging.

   In the present embodiment, the second period tb is a period synchronized with a period for performing other adjustments (for example, adjustment of image forming conditions in process control such as density adjustment).

  In the present embodiment, the setting of the rotational drive control of the photosensitive drums 3a, 3b, 3c, and 3d for black, cyan, magenta, and yellow is performed after the end of the job.

  FIG. 22 is a flowchart illustrating an exemplary flow of a process of executing a periodic first correction operation. FIG. 23 is a flowchart illustrating an exemplary flow of a process of executing a periodic second correction operation.

  In the processing example of the periodic first correction operation shown in FIG. 22, when the job ends (step S20), the control unit 600 first determines whether or not the first period (here, 4 hours) has passed ( In step S21), if the first period has not passed (step S21: No), the process is terminated, while if the first period has passed (step S21: Yes), the process proceeds to step S22. Note that the first correction operation proceeds to step S22 regardless of the first period.

  Next, the photosensitive drums 3a and 3b for black, cyan, magenta and yellow are detected by the peripheral speed sensors 170a, 170b, 170c and 170d for black, cyan, magenta and yellow by the first coarse / fine wave detecting means P1, respectively. , 3c, 3d are respectively measured (step S22), and the first correction waves αa, αb, αc, αd (see FIG. 10) are used as the first correction waves α1a, α1b, α1c and α1d (see FIG. 11) are respectively calculated (step S23), and the process ends. At this time, the first correction waves α1a, α1b, α1c, and α1d are stored (set) in the nonvolatile memory of the storage unit 620 (see FIG. 7) of the control unit 600.

  In the processing example of the periodic second correction operation shown in FIG. 23, when the job ends (step S30), the control unit 600 first determines whether or not the second period (here, 1 hour) has passed ( If the second period has not passed (step S31: No), the process ends. On the other hand, if the second period has passed (step S31: Yes), the process proceeds to step S32. Note that the first time of the second correction operation proceeds to step S32 regardless of the second period.

  Next, the control unit 600 uses the first rotation control means P2 to speed based on the first correction waves α1a, α1b, α1c, and α1d stored (set) in the nonvolatile memory of the storage unit 620 in the first correction operation. A pulse signal is inputted to each of the driving units 420a, 420b, 420c, and 420d for black, cyan, magenta, and yellow, and each of the photosensitive units for black, cyan, magenta, and yellow by the respective driving units 420a, 420b, 420c, and 420d. The rotational driving of the photosensitive drums 3a, 3b, 3c, and 3d is controlled (step S32), and the rotation unevenness of the photosensitive drums 3a, 3b, 3c, and 3d due to the first factor is suppressed (see FIG. 13). Each image pattern for black, cyan, magenta and yellow is formed on the intermediate transfer belt 7 by the image pattern transfer control means P3. Pa, Pb, Pc, Pd (see FIG. 5 and FIG. 6) for transferring each (step S33).

  Next, the control unit 600 uses the second coarse / fine wave detection means P4 to detect the black, cyan, magenta, and yellow image patterns Pa, Pb, Pc, and Pd on the intermediate transfer belt 7 by the image pattern sensor 190. The two coarse waves βa, βb, βc, βd (see FIG. 16) are read (step S34), and the second correction waves β1a, β1b, β1c, β1d (see FIG. 17) are respectively read by the second correction wave generating means P7. Calculation is performed (step S35).

  Next, the control unit 600 combines the first correction waves α1a, α1b, α1c, α1d and the second correction waves β1a, β1b, β1c, β1d by the combined correction wave generation means P8, and combines the corrected waves γa, γb, γc and γd (see FIG. 18) are respectively generated (step S36), and the combined correction waves γa, γb, γc, and γd are stored (set) in the nonvolatile memory of the storage unit 620 (step S37). Then, at the time of the next and subsequent jobs, the second rotation control means P5 converts the speed pulse signals based on the combined correction waves γa, γb, γc, and γd in the storage unit 620 to the driving units for black, cyan, magenta, and yellow. 420a, 420b, 420c, and 420d are respectively input to control the rotational driving of the photosensitive drums 3a, 3b, 3c, and 3d for black, cyan, magenta, and yellow by the driving units 420a, 420b, 420c, and 420d, respectively. The correction control to be reflected is reflected. By doing this, each of the black, cyan, magenta, and yellow colors is detected based on the detection result of the rotation unevenness due to the combination of the first factor and the second factor that have been reduced to reduce the rotation unevenness due to the first factor. The peripheral speed of the photosensitive drums 3a, 3b, 3c, 3d can be controlled (see FIG. 19).

(About this embodiment)
According to the first to third embodiments, first, the first coarse / fine wave αa indicating fluctuations in the peripheral speed detected by the peripheral speed sensors 170a, 170b, 170c, and 170d for black, cyan, magenta, and yellow. , Αb, αc, αd are detected, and black, cyan by the respective drive units 420a, 420b, 420c, 420d for black, cyan, magenta, and yellow so as to cancel the detected first dense waves αa, αb, αc, αd. By controlling the rotational drive of the photosensitive drums 3a, 3b, 3c, 3d for magenta and yellow, the dimensional accuracy of the drive transmission unit (here, the shaft gears 461a, 461b for black, cyan, magenta, and yellow) , 461c, 461d or / or further photosensitive member driving gears 462a, 462 for black, cyan, magenta and yellow. b, 462c, 462d eccentricity and gear accuracy) can be performed to reduce rotation unevenness due to the first factor. Next, in the state where the rotation unevenness due to the first factor is reduced, the image patterns Pa, Pb for black, cyan, magenta, and yellow on the photosensitive drums 3a, 3b, 3c, 3d that are driven and controlled. , Pc, Pd are transferred onto the intermediate transfer belt 7 and transferred to the second transfer density indicating the deviation of the image patterns Pa, Pb, Pc, Pd on the intermediate transfer belt 7 detected by the image pattern sensor 190. Waves βa, βb, βc, and βd are detected, and the driving units 420a, 420b, 420c, and 420d are detected based on the detected first dense waves αa, αb, αc, and αd and the second dense waves βa, βb, βc, and βd. A factor that combines the first factor and the second factor that have been subjected to the reduction process for reducing the rotation unevenness due to the first factor by controlling the rotational driving of the photosensitive drums 3a, 3b, 3c, and 3d by Accordingly, the peripheral speed of each of the photosensitive drums 3a, 3b, 3c, and 3d can be controlled based on the detection result of the rotation unevenness (that is, the rotation unevenness that has become relatively small). More than the conventional image forming apparatus that controls the peripheral speed of the image carrier based on the detection result of the rotation unevenness (that is, the rotation unevenness that remains relatively large) due to the factor combined with the second factor, each photosensitive drum 3a, The rotational drive of 3b, 3c, and 3d can be controlled with high accuracy, and thereby it is possible to reliably reduce the image displacement. This is because, as in the present embodiment, the image forming apparatus 100 includes a plurality of photosensitive drums 3a, 3b, 3c, 3d, and a plurality of photosensitive drums 3a corresponding to images of different colors. , 3b, 3c, 3d are formed at the same timing, and a plurality of color images respectively formed on the plurality of photosensitive drums 3a, 3b, 3c, 3d are transferred onto the transfer member in an overlapping manner. This is especially effective when

  By the way, as in the present embodiment, the drive transmission units 460a, 460b, 460c, and 460d for black, cyan, magenta, and yellow are respectively driven by the drive units 420a, 420b, black, cyan, magenta, and yellow. First drive transmission rotating members (here, black, cyan, magenta, and yellow shaft gears 461a, 461b, 461c, and 461d) provided on 420c and 420d, and photosensitive materials for black, cyan, magenta, and yellow, respectively. And a plurality of second drive transmission rotating members (here, black, cyan, magenta and yellow photoconductor drive gears 462a, 462b, 462c, 462d) provided on the body drums 3a, 3b, 3c, 3d. If the drive transmission rotating member is provided, the first drive transmission rotating member If the value of the peripheral speed ratio between the peripheral speed and the peripheral speed of the second drive transmission rotating member is not an integer, the first rotation control means uses data for one circumference of each of the photosensitive drums 3a, 3b, 3c, 3d. Since it is impossible to control the rotational drive of the photosensitive drums 3a, 3b, 3c, 3d by the P2 and the second rotation control means P5, the control configuration of the first rotation control means P2 and the second rotation control means P5 is as follows. To be complicated.

  In this regard, in the first to third embodiments, the value of the peripheral speed ratio between the peripheral speed of the first drive transmission rotating member and the peripheral speed of the second drive transmission rotating member is an integer of 1 or more. As a result, the black, cyan, magenta, and yellow photoconductor drums 3a, 3b, 3c, and 3d are used for the first rotation control means P2 and the second rotation control means P5, respectively. It is possible to control the rotational drive of the photosensitive drums 3a, 3b, 3c, 3d for magenta and yellow, and to simplify the control configuration of the first rotation control means P2 and the second rotation control means P5 accordingly. Can do.

  Further, in the first to third embodiments, the first coarse / fine wave detecting means P1 uses the black, cyan, magenta, and yellow peripheral speed sensors 170a, 170b, 170c, and 170d for black, cyan, magenta, and yellow. Average the value of the first coarse / dense wave for a plurality of rounds of each of the photosensitive drums 3a, 3b, 3c, and 3d for yellow, or / and / or further, average one round of the photosensitive drums 3a, 3b, 3c, and 3d The second coarse / fine wave detection means P4 uses the image pattern sensor 190 to obtain the second coarse / fine wave values of the photosensitive drums 3a, 3b, 3c, and 3d for the circumferences of the photosensitive drums 3a, 3b, 3c, and 3d. By averaging over one round, a first round of the first averaged from the values of the first coarse and dense waves αa, αb, αc, αd for a plurality of rounds of each of the photosensitive drums 3a, 3b, 3c, 3d. Values of the dense waves αa, αb, αc, αd, Alternatively / in addition, second round dense waves βa, βb, one round averaged from the values of the second round dense waves βa, βb, βc, βd for a plurality of rounds of the photosensitive drums 3a, 3b, 3c, 3d, respectively. The values of βc and βd can be used, and accordingly, the rotational drive control of the photosensitive drums 3a, 3b, 3c, and 3d can be performed with high accuracy.

  By the way, when the peripheral speed sensors 170a, 170b, 170c, and 170d for black, cyan, magenta, and yellow are single, the peripheral speed sensors 170a, 170b, 170c, and 170d have black, cyan, The detected parts 32a, 32b, 32c, and 32d for magenta and yellow are deviated from the rotation centers of the photosensitive drums 3a, 3b, 3c, and 3d for black, cyan, magenta, and yellow (eccentric. ), The detection accuracy (measurement accuracy) of the circumferential speed of each of the photosensitive drums 3a, 3b, 3c, and 3d is deteriorated.

  In this regard, in the first to third embodiments, the detected portions 32a for black, cyan, magenta, and yellow of the peripheral speed sensors 170a, 170b, 170c, and 170d for black, cyan, magenta, and yellow are used. , 32b, 32c, and 32d, even if the rotational speeds of the photosensitive drums 3a, 3b, 3c, and 3d for black, cyan, magenta, and yellow are shifted from each other, the peripheral speed sensors 170a, 170b, 170c, and 170d , A plurality of peripheral speed sensors (171a, 172a), (171b, 172b), (171c, 172c), (171d, 172d) for black, cyan, magenta, and yellow, and the peripheral speed sensors (171a, 172a). ), (171b, 172b), (171c, 172c), (171d, 1 2d) is provided uniformly along the circumferential direction of each of the photosensitive drums 3a, 3b, 3c, 3d, so that each detected portion 32a, obtained from each circumferential speed sensor 170a, 170b, 170c, 170d By averaging the detection values at the corresponding positions in 32b, 32c, and 32d, it is possible to improve the detection accuracy (measurement accuracy) of the peripheral speed of each of the photosensitive drums 3a, 3b, 3c, and 3d.

  Further, in the second embodiment, when an input operation is accepted, black is detected by the first rotation control means P2 following the detection of the first coarse / fine waves αa, αb, αc, αd by the first coarse / fine wave detection means P1. Control of rotation driving of the photosensitive drums 3a, 3b, 3c, 3d for cyan, magenta and yellow, and image patterns Pa, Pb, Pc, Pd for black, cyan, magenta and yellow by the image pattern transfer control means P3 By forcing a series of correction operations to transfer the image onto the intermediate transfer belt 7 and detect the second coarse / fine waves βa, βb, βc, βd by the second coarse / fine wave detection means P4. In this case, the image forming apparatus 100 can be made to perform an operation for reducing the positional deviation of the image.

  By the way, the detection time from the start to the end of detection of the first coarse / fine waves αa, αb, αc, αd by the first coarse / fine wave detection means P1 is black, cyan, magenta and yellow by the first rotation control means P2. Control of the rotation of the photosensitive drums 3a, 3b, 3c, 3d for use is started, and then the image patterns Pa, Pb, Pc, Pd for black, cyan, magenta, and yellow by the image pattern transfer control means P3. After the transfer onto the intermediate transfer belt 7, the time until the second coarse / fine wave detection means P4 detects the second coarse / fine waves βa, βb, βc, βd tends to be longer. On the other hand, fluctuations between the detected values of the first coarse / fine waves αa, αb, αc, αd by the first coarse / fine wave detection means P1 are caused by the second coarse / fine waves βa, βb, Since the detection values of βc and βd are less than the fluctuations between the detection values, the detection frequency of the detection values of the first coarse / fine waves αa, αb, αc, and αd by the first coarse / fine wave detection means P1 is second. Even if the detection frequency of the detected values of the second coarse / fine waves βa, βb, βc, and βd by the coarse / fine wave detection means P4 is less than the detection accuracy, the detection accuracy is hardly lowered.

  In this regard, in the third embodiment, the first coarse / fine waves αa, αb, αc, and αd are detected by the first coarse / fine wave detection means P1 every first period ta and are smaller than the first period ta. Every second period tb, the first rotation control means P2 controls the rotation drive of the photosensitive drums 3a, 3b, 3c and 3d for black, cyan, magenta and yellow, and the black and cyan colors by the image pattern transfer control means P3. The magenta and yellow image patterns Pa, Pb, Pc, and Pd are transferred onto the intermediate transfer belt 7, and the second coarse / fine waves βa, βb, βc, and βd are detected by the second coarse / fine wave detection means P4. In the state where the detection frequency by the first coarse / fine wave detection means P1 whose detection time tends to be long is suppressed as much as possible, and the detection accuracy of the first coarse / fine waves αa, αb, αc and αd is maintained. Body Arm 3a, it is possible to perform 3b, 3c, the control of the rotation of the 3d.

  In the third embodiment, the second period tb is set to a period synchronized with a period for performing other adjustments (for example, adjustment of image forming conditions in process control such as density adjustment), so that black, cyan, magenta In addition, the rotational drive control of each of the photosensitive drums 3a, 3b, 3c, and 3d for yellow can be performed in combination with other adjustments, and accordingly, the downtime of the image forming apparatus 100 (image formation incapable of image formation by the correction operation). Increase in unavailable time) can be suppressed.

  By the way, if the setting of the rotational drive control of the photosensitive drums 3a, 3b, 3c, 3d for black, cyan, magenta, and yellow is performed before or during the job, the photosensitive drums 3a, 3b, 3c, 3d. Since the job is ended after setting the rotational drive control, the operator waits for the time for setting the rotational drive control of each of the photosensitive drums 3a, 3b, 3c, and 3d. Become.

  In this regard, in the third embodiment, the setting of the rotational drive control of the photosensitive drums 3a, 3b, 3c, and 3d for black, cyan, magenta, and yellow is performed after the job is completed, so that the operator can It is possible to avoid waiting for the time for setting the rotational drive control of the photosensitive drums 3a, 3b, 3c, and 3d.

  In the first to third embodiments, the first correction wave generation unit P6, the second correction wave generation unit P7, and the combined correction wave generation unit P8 are further provided. The second rotation control unit P5 includes: Black, cyan, magenta, and yellow by the driving units 420a, 420b, 420c, and 420d for black, cyan, magenta, and yellow using the combined correction waves γa, γb, γc, and γd generated by the combined correction wave generation unit P8. By controlling the rotational drive of each photosensitive drum 3a, 3b, 3c, 3d for use, the rotational drive control structure of each photosensitive drum 3a, 3b, 3c, 3d by each drive unit 420a, 420b, 420c, 420d Can be simplified.

  In the first to third embodiments, at least one of the first correction wave generation means P6 and the second correction wave generation means P7 has a predetermined coefficient for the basic amplitude of the basic correction wave ε. And a shift of a predetermined phase to generate a correction wave corresponding to the at least one correction wave generation unit, thereby simplifying the control configuration for calculating the correction wave. .

  In the present embodiment, a color image forming apparatus including a plurality of photosensitive drums 3a, 3b, 3c, and 3d is used as the image forming apparatus 100. However, a monochrome image including a single photosensitive drum 3a is used. A forming apparatus may be used.

  In the present embodiment, the photosensitive drums 3a, 3b, 3c, and 3d are used as the image carrier, but a photosensitive belt wound around a plurality of rollers may be used.

  The present invention is not limited to the embodiment described above, and can be implemented in various other forms. Therefore, such an embodiment is merely an example in all respects and should not be interpreted in a limited manner. The scope of the present invention is shown by the scope of claims, and is not restricted by the text of the specification. Further, all modifications and changes belonging to the equivalent scope of the claims are within the scope of the present invention.

3a Photosensitive drum for black (an example of an image carrier)
3b Cyan photoreceptor drum (an example of an image carrier)
3c Photosensitive drum for magenta (an example of an image carrier)
3d yellow photosensitive drum (an example of an image carrier)
7 Intermediate transfer belt (an example of a transfer member)
31a Rotating shaft 31b Rotating shaft 31c Rotating shaft 31d Rotating shaft 32a Black detected portion 32b Cyan detected portion 32c Magenta detected portion 32d Yellow detected portion 100 Image forming apparatus 170a Black peripheral speed sensor (circumferential speed detection) Example)
170b Cyan peripheral speed sensor (an example of a peripheral speed detector)
170c Magenta peripheral speed sensor (an example of a peripheral speed detector)
170d Peripheral speed sensor for yellow (an example of a peripheral speed detection unit)
171a Black peripheral speed sensor 171b Cyan peripheral speed sensor 171c Magenta peripheral speed sensor 171d Yellow peripheral speed sensor 172a Black peripheral speed sensor 172b Cyan peripheral speed sensor 172c Magenta peripheral speed sensor 172d Yellow peripheral speed sensor 181 Light emission Unit 182 light receiving unit 190 image pattern sensor (an example of an image pattern detection unit)
190a first image pattern sensor 190b second image pattern sensor 191 light emitting unit 192 light receiving unit 200 image reading device 300 image forming apparatus main body 330 image forming unit 400 driving unit 420a black driving unit 420b cyan driving unit 420c magenta driving unit 420d Yellow driving portion 421a Rotating shaft 421b Rotating shaft 421c Rotating shaft 421d Rotating shaft 460a Black drive transmission portion 460b Cyan drive transmission portion 460c Magenta drive transmission portion 460d Yellow drive transmission portion 461a Black shaft gear 461b Cyan shaft gear 461c Magenta shaft gear 461d Yellow shaft gear 462a Black photoconductor drive gear 462b Cyan photoconductor drive gear 462c Magenta photoconductor drive gear 462d Yellow photoconductor drive gear 500 Drive control Road 520a black control circuit 520b for cyan control circuit 520c for magenta control circuit 520d for yellow control circuit 600 the control unit 610 processor 620 memory unit P recording sheet (one example of a recording material)
P1 first coarse / fine wave detection means P2 first rotation control means P3 image pattern transfer control means P4 second coarse / fine wave detection means P5 second rotation control means P6 first correction wave generation means P7 second correction wave generation means P8 synthetic correction wave Generation means Pa Black image pattern Pb Cyan image pattern Pc Magenta image pattern Pd Yellow image pattern SL1 Light shielding portion SL2 Slit ta First period tb Second period α1a First correction wave α1b First correction wave α1c First correction wave α1d first correction wave αa first coarse wave αb first coarse wave αc first coarse wave αd first coarse wave β1a second correction wave β1b second correction wave β1c second correction wave β1d second correction wave βa second coarse wave βb second dense wave βc second dense wave βd second coarse wave γa synthetic correction wave γb synthetic correction wave γc synthetic correction wave γd synthetic correction wave ε basic correction wave

Claims (12)

An image carrier that carries an image, a drive unit that rotationally drives the image carrier, a peripheral speed detector that detects a peripheral speed of the image carrier that is rotationally driven by the drive unit, and an image sensor on the image carrier An image forming apparatus comprising: a transfer member to which an image pattern is transferred; and an image pattern detection unit that detects the image pattern on the transfer member,
First coarse and dense wave detecting means for detecting a first coarse and dense wave indicating fluctuations in the peripheral velocity detected by the peripheral velocity detection unit;
First rotation control means for controlling rotational driving of the image carrier by the drive unit so as to cancel the first coarse / fine wave detected by the first coarse / fine wave detection means;
Image pattern transfer control means for forming the image pattern on the image carrier that is driven and controlled by the first rotation control means and transferring the image pattern to the transfer member;
Second coarse / fine wave detection means for detecting a second coarse / fine wave indicating the deviation of the image pattern on the transfer member, which is transferred by the image pattern transfer control means and detected by the image pattern detection unit;
Rotational driving of the image carrier by the drive unit is controlled based on the first dense wave detected by the first dense wave detector and the second dense wave detected by the second dense wave detector. An image forming apparatus comprising: a second rotation control unit. The image forming apparatus according to claim 1,
A drive transmission unit that transmits rotational drive from the drive unit to the image carrier;
The peripheral speed detection unit detects a peripheral speed of the image carrier that is rotationally driven by the drive unit via the drive transmission unit,
The drive transmission unit includes a plurality of drive transmission rotation members including at least a first drive transmission rotation member provided in the drive unit and a second drive transmission rotation member provided in the image carrier. ,
An image forming apparatus, wherein a value of a peripheral speed ratio between a peripheral speed of the first drive transmission rotating member and a peripheral speed of the second drive transmission rotating member is an integer of 1 or more. The image forming apparatus according to claim 1, wherein:
The first coarse / fine wave detecting means detects the first coarse / fine wave of a plurality of turns of the image carrier at the peripheral velocity detection unit, and the value of the first coarse / fine wave of the plurality of turns is the image carrier. Or the second coarse / fine wave detection means detects the second coarse / fine wave for a plurality of turns of the image carrier by the image pattern detection unit, and the plurality of turns. An image forming apparatus characterized in that a second coarse / fine wave having a minute value is averaged over one rotation of the image carrier. An image forming apparatus according to any one of claims 1 to 3, wherein
The peripheral speed detector is a plurality of peripheral speed detectors, and the plurality of peripheral speed detectors are provided uniformly along the circumferential direction of the image carrier. . The image forming apparatus according to any one of claims 1 to 4, wherein:
When an input operation is received, following the detection of the first coarse / fine wave by the first coarse / fine wave detection means, the rotation control of the image carrier by the first rotation control means, the image pattern transfer control means An image forming apparatus for forcibly executing a series of correction operations for performing transfer of the image pattern onto the transfer member and detection of the second coarse / fine wave by the second coarse / fine wave detection means. The image forming apparatus according to any one of claims 1 to 4, wherein:
The first coarse / fine wave detection means detects the first coarse / fine wave every predetermined first period, and every predetermined second period smaller than the first period, Control of rotation driving of the image carrier by the first rotation control means, transfer of the image pattern onto the transfer member by the image pattern transfer control means, and detection of the second density wave by the second density wave detection means. An image forming apparatus. The image forming apparatus according to claim 6,
2. The image forming apparatus according to claim 1, wherein the second period is a period synchronized with a period for performing other adjustments. The image forming apparatus according to claim 6 or 7,
The image forming apparatus according to claim 1, wherein the setting of the rotation driving control of the image carrier is performed after the job is completed. The image forming apparatus according to any one of claims 1 to 8, wherein
First correction wave generating means for generating a first correction wave for controlling rotation driving of the image carrier by the drive unit so as to cancel the first coarse / fine wave detected by the first coarse / fine wave detection means; ,
Second correction wave generating means for generating a second correction wave for controlling the rotational drive of the image carrier by the drive unit so as to cancel the second dense wave detected by the second coarse / fine wave detection means; ,
A combined correction wave generating unit that generates a combined correction wave by combining the first correction wave generated by the first correction wave generating unit and the second correction wave generated by the second correction wave generating unit; Prepared,
The second rotation control unit controls rotation driving of the image carrier by the drive unit using the combined correction wave generated by the combined correction wave generating unit. The image forming apparatus according to claim 9, wherein
At least one of the first correction wave generation means and the second correction wave generation means has a basic amplitude and a basic distance with one period of one round of the surface of the image carrier. Image formation characterized in that a correction wave corresponding to at least one of the correction wave generation means is generated by multiplying the basic amplitude of the correction wave by a predetermined coefficient and shifting it by a predetermined phase. Dress. An image forming apparatus according to any one of claims 1 to 10, wherein
A plurality of the image carriers, and a plurality of different color images are formed on the plurality of image carriers corresponding to the images at the same timing, and the plurality of colors formed on the plurality of image carriers, respectively. An image forming apparatus, wherein an image is transferred while being superimposed on a transfer member. An image carrier that carries an image, a drive unit that rotationally drives the image carrier, a peripheral speed detector that detects a peripheral speed of the image carrier that is rotationally driven by the drive unit, and an image sensor on the image carrier An image misalignment correction method for an image forming apparatus, comprising: a transfer member to which an image pattern is transferred; and an image pattern detection unit that detects the image pattern on the transfer member.
Detecting the first coarse / fine wave indicating the fluctuation of the peripheral velocity detected by the peripheral velocity detection unit, and controlling the rotational drive of the image carrier by the drive unit so as to cancel the detected first coarse / fine wave; The image pattern is formed on the image carrier subjected to drive control, transferred to the transfer member, transferred and detected by the image pattern detection unit to indicate a shift of the image pattern on the transfer member. A method for correcting image misregistration, comprising detecting a density wave, and controlling the rotational drive of the image carrier by the drive unit based on the detected first density wave and the second density wave.

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