JP2006078851A - Color image forming apparatus, its adjustment method and software - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a color image forming apparatus capable of shortening time needed to acquire the minimum rotation phase for an amount of positional deviation, while satisfying the performance of the image forming apparatus. <P>SOLUTION: The color image forming apparatus includes: replaceable cartridges 7 for respective colors, which have respective image carriers; replacement detectors 28 for detecting replacement of the corresponding cartridges for the respective colors; motors for rotating the image carriers in the corresponding cartridges for the respective colors; an endless belt 11 passed along the cartridges for the respective colors in order; a pattern forming means for forming positional deviation detection patterns onto the endless belt; an image detection sensor 44 for detecting the positional deviation detection patterns formed by the pattern forming means; a processing means for performing the process of acquiring the minimum rotation phase for an amount of positional deviation based upon the detection result of the image detection sensor; adjusting means for adjusting the rotation phase of the corresponding drive means for the respective colors so as to reach the minimum rotation phase for the amount of positional deviation, acquired by the processing means; and a control means by which only the cartridge with which the previous cartridge has been replaced, which is detected by the replacement detector 28, is subject to the process of acquiring the minimum rotation phase for the amount of positional deviation by the processing means. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a color image forming apparatus such as a color copying machine or a color printer, and more particularly to the reduction of color misregistration.

  2. Description of the Related Art Conventionally, there is a color image forming apparatus called a so-called inline system in which photosensitive drums that form a plurality of image carriers are arranged in a line. This is because yellow, magenta, cyan, and black are transferred by four photosensitive drums arranged along the transfer material conveyance path while carrying and conveying the transfer material by an electrostatic transfer belt stretched by a plurality of rollers. Are sequentially transferred onto a sheet, and a color image is formed by superimposing each color.

  This configuration has attracted attention in recent years because it can perform printing at high speed. However, since each color is formed by four photosensitive drums, a configuration in which colors are superimposed on one photosensitive drum via four conveyance paths for each color (hereinafter simply referred to as “four-pass method”). Compared to the color image forming apparatus (1)), a higher accuracy is required for rotational driving of the photosensitive drum.

  In other words, a gear train is generally used for driving the photosensitive drum, and low-frequency rotation unevenness such as one rotation component of the gear always occurs. However, in the case of the 4-pass system, the reduction ratio of the drive gear train is an integer. By combining them, it is possible to avoid the accumulated pitch error of the gears and to adjust the image forming positions of the respective colors.

  However, in the case of the in-line method, since the plurality of photosensitive drums are independent, the drive gear train is also independent, and it is difficult to take a workaround like the above-described 4-pass method, and the image forming positions of the respective colors are The image quality is liable to deteriorate due to the color shift due to the shift.

Conventionally, as measures against color misregistration, measures such as detecting the angular velocity of the photosensitive drum or reading an image transferred onto a transfer material to detect the velocity unevenness and controlling the rotation of the motor to cancel the velocity unevenness, As disclosed in Patent Document 1 and Patent Document 2, measures have been taken to reduce relative color misregistration by matching the rotational phase of each photosensitive drum to a desired state.
JP-A-9-146329 JP-A-10-333398

  However, in the above-described conventional example, the driving of the image carrier that forms the photosensitive drum is a reduction system via a plurality of gears. It becomes a complicated speed waveform including a component of one rotation cycle. For this reason, high-precision speed unevenness detection means and motor control are required, and even if the phase of the photosensitive drum is adjusted, the influence of the intermediate gear remains, and in order to accurately detect the drive unevenness of one rotation period of the image carrier. Therefore, it is necessary to shift the rotational phase of the detected color with respect to the reference color and to detect a relative positional shift with respect to each detected color with respect to the reference color by the positional shift detection pattern for each rotational phase. Furthermore, even if only one process cartridge is replaced, detection is performed to match the rotational phases of all the process cartridges that have not been replaced, and extra detection time is required for the process cartridges that do not require detection of the rotational phase. It was.

  The present invention has been made under such circumstances, and provides a color image forming apparatus capable of shortening the time for obtaining the rotational phase with the minimum displacement while satisfying the performance of the image forming apparatus. This is a problem.

  In order to solve the above problems, in the present invention, a color image forming apparatus is configured as described in (1) below.

(1) each color cartridge having an image carrier and configured to be replaceable;
Replacement detection means for detecting replacement of the cartridges of the respective colors;
Each color driving means for rotating and driving the image carrier in each color cartridge;
An endless belt that sequentially passes through the cartridges of the respective colors;
Pattern forming means for forming a pattern for detecting displacement on the endless belt;
Pattern detecting means for detecting a pattern for detecting misregistration formed by the pattern forming means;
Processing means for performing processing for obtaining a rotational phase with a minimum amount of displacement based on a detection result of the pattern detection means;
Adjusting means for adjusting the rotational phase of the driving means for each color so as to be the rotational phase with the minimum positional deviation obtained by the processing means;
Control means;
A color image forming apparatus comprising:
The color image forming apparatus, wherein the control unit causes the processing unit to perform a process of obtaining a rotational phase with a minimum positional deviation amount only on the cartridge whose replacement is detected by the replacement detection unit.

  According to the present invention, it is possible to reduce the time for acquiring the rotational phase with the minimum positional deviation amount while satisfying the performance of the image forming apparatus.

  Hereinafter, the best mode for carrying out the present invention will be described in detail with reference to examples. The present invention is not limited to the form of an apparatus, but can be implemented in the form of a method and software for realizing the method, supported by the description of the embodiments.

  FIG. 1 is a cross-sectional view illustrating a configuration of a “color image forming apparatus” according to the first exemplary embodiment. In FIG. 1, a color image forming apparatus 100 includes four electrophotographic photosensitive drums 1y, 1m, 1c, and 1k for yellow, magenta, cyan, and black, which are image carriers linearly arranged in the vertical direction. (Hereinafter simply referred to as “photoreceptor drum 1”), and a transfer material conveying belt that serves as a transfer material carrier that adsorbs and conveys the transfer material S by electrostatic attraction facing each photoconductor drum 1. (Endless belt) 11 is arranged.

  Each of the photosensitive drums 1 is fixed to a drum shaft that is a rotation shaft of the photosensitive drum 1, and is engaged with a coupling 36 that is a first engaging member, which will be described in detail later, and the coupling 36. A rotational driving force is transmitted from a driving motor (not shown) serving as a driving source to the gear 18 on the coupling 33 side serving as a second engaging member to be coupled to be rotated counterclockwise in FIG. a) and (b)).

  Around each photosensitive drum 1, primary chargers 2 a, 2 b, 2 c, and 2 d (hereinafter simply referred to as “charging devices”) for charging the surface of the photosensitive drum 1 uniformly in order from the upstream side in the rotation direction. Exposure unit 3a for forming an electrostatic latent image by irradiating the surface of the photosensitive drum 1 uniformly charged by the primary charger 2 with a laser beam based on image information. 3b, 3c, 3d (hereinafter simply referred to as "exposure means 3") are arranged.

  Further, developing means 4a, 4b, 4c, 4d (hereinafter simply referred to as "developing means 4") that make each color toner adhere to the surface of the photosensitive drum 1 on which the electrostatic latent image is formed, and visualize it as a toner image. Cleaning means 6a, 6b, 6c, 6d (hereinafter simply referred to as “cleaning means 6”) for removing toner remaining on the surface of the photosensitive drum 1 after transfer are disposed.

  The photosensitive drum 1, the primary charger 3, the developing unit 5, and the cleaning unit 6 are integrated into the apparatus main body 100 as process cartridges 7 a, 7 b, 7 c, and 7 d (hereinafter simply referred to as “process cartridge 7”). On the other hand, it is configured to be detachable. Further, the apparatus main body has detectors 28a, 28b, 28c, 28d (hereinafter simply referred to as “exchange detector 28”) for detecting the replacement of the process cartridge, and memories 8a, 8b, 8c, 8d attached to the process cartridge. Is detected during the initialization operation.

  In addition, a transfer material conveying belt (endless belt) 11 is sandwiched between the transfer material conveying belts 11 on the surface of the photosensitive drum 1 at positions facing the respective photosensitive drums 1. Transfer rollers 12a, 12b, 12c and 12d (hereinafter simply referred to as “transfer roller 12”) serving as transfer means for transferring the toner image are arranged.

  The drive unit is positioned in front of the left side of the machine and applies a rotational driving force to the process cartridges of four colors arranged in a substantially vertical direction. Each process cartridge 7 includes the photosensitive drum 1, the developing unit 4, the cleaning unit 6 and the like, and supplies all of these driving forces.

  Since the process cartridge 7 can be detached and attached independently for each color, the drive transmission unit is also arranged in a substantially vertical direction independently for each color and directly transmits to the photosensitive drum 1 that requires rotational accuracy. For example, the driving of the developing unit 4 and the cleaning unit 6 may be transmitted in another series. The driving force supplied to the process cartridge 7 is distributed to each element by a driving system in the process cartridge 7.

  As shown in FIGS. 2A and 2B, the driving means includes a gear 18 for driving the process cartridge 7, a shaft portion 32a that rotates together with the gear, and a shaft portion. The coupling portion 33 that rotates to transmit the rotational driving force to the process cartridge 7 and the drum shaft 22 that is fixed concentrically with the photosensitive drum 1 are integrated with the positioning hole 34 for determining the position. It consists of This integral component can be a resin molded product.

  As shown in FIG. 2, the shaft portion 32a is supported by the cylinder bearing portion 35 installed on the main body side so that only the shaft portion 32a in the vicinity of the gear root is freely rotated and linearly moved. The periphery of the portion 33 is determined by fitting the positioning hole 34 to the drum shaft 22 to be described later, so that it does not conflict with the shaft position, and does not interfere with the coupling. A supportable clearance is provided.

  Although the gear shaft is inclined due to the positional accuracy of the cylinder bearing portion 35 and the drum shaft 22, the distance from the shaft portion 32 a near the gear root to the positioning hole 34 is made sufficiently long so as not to cause any actual harm.

  The gear 18 and the integral part are movable in the axial direction, and are pressed toward the photosensitive drum 1 by a plate spring 37.

  A drum shaft 22 that rotates integrally with the photosensitive drum 1 is fixed to the photosensitive drum 1 using a parallel pin 25, and the drum shaft 22 is accurately positioned on the machine body via a bearing 38. Yes.

  A non-driving side (driven side) coupling 36 is fixed to the end of the drum shaft 22, and meshes with the driving side (main driving side) coupling 33 to transmit the rotational driving force.

  As shown in FIGS. 2A and 2B, the driving side coupling 33 and the non-driving side coupling 36 are triangular spiral couplings, and when driven in a predetermined direction, the two sides always engage with each other. It has become.

  In FIG. 3, the motors 41y, 41m, 41c and 41k (hereinafter referred to as motor 41) provided exclusively for the respective photosensitive drums 1y, 1m, 1c and 1k (hereinafter referred to as photosensitive drum 1) are engaged with the photosensitive drum 1. The photosensitive drum 1 is driven through the gear 18.

  The tooth 31 of the gear 18 is provided with a target for detecting the phase, and a phase signal is detected once per rotation by an optical or magnetic phase detector (42y, 42m, 42c, 42k) 42. can do.

  Further, an image detection sensor 44 is provided so as to face the transfer material conveyance belt 11, and an image on the transfer material conveyance belt 11 can be optically detected.

  In the configuration of this embodiment, the main component of the angular velocity unevenness is only one rotation cycle of the photosensitive drum 1, so that a pattern formed on the photosensitive drum 1 at equal time intervals is transferred to the transfer material conveying belt 11. Then, when read by the image detection sensor 44 and the accumulated fluctuation component of the pattern interval is obtained, a sine waveform as shown in FIG. 4 is obtained.

  In FIG. 4, the horizontal axis represents the distance from the front end of the image, and the vertical axis represents the amount of displacement. In order to obtain the phase relationship of the four colors, processing is performed by creating and detecting one color at a time while managing the image formation start timing of each color, obtaining a sine waveform, correcting the comparison by the start timing interval, and comparing them. Just do it.

  Further, as shown in FIG. 4, when Bk is used as a reference, the color shift relative to the Bk color can be reduced by shifting the Y color by the distance y toward the image leading end. Similarly, the M color may be shifted by the distance m, and the C color may be shifted by the distance c. However, since this phase detection requires a predetermined time, if it is frequently performed, a loss of image forming time occurs.

  Therefore, a phase detector 42 that detects the phase of the gear 18 that rotates the photosensitive drum 1 is used, and control is usually performed based on this phase information.

  If the phase waveform detected by the phase detector 42 is in a state as shown in FIG. 5, the phase of the Y-color gear 18y is controlled so as to be turned earlier by a time yp corresponding to the distance y in FIG. , The relative color shift between the Bk color and the Y color decreases. Similarly, the M color gear 18m may be phase-adjusted so that the time m-p is faster than the distance m, and the C-color gear 18c is turned faster than the distance c by the time cp. The phase can be adjusted by adjusting the speed of the motor 41.

  When such a phase adjustment is performed and the above-described phase relationship is obtained, the result is as shown in FIG. 6, and the relative color shift can be reduced to about ½ or less.

  A misregistration detection pattern as shown in FIG. 7 is formed on the transfer material conveyance belt 11 and is read by the image detection sensors 44 provided on both sides of the transfer material conveyance belt 11 to detect the misregistration amount of each color.

  FIG. 7 shows a pattern for detecting a positional deviation amount in the paper transport direction. In this example, a reference color a (hereinafter Bk: black) is detected on one side, and a detection color b (hereinafter Y: yellow, M: magenta, C: cyan). a1 to a19 and b1 to b19 indicate the detection timing of each pattern. The arrows indicate the conveyance direction of the transfer material conveyance belt 11.

  In the misregistration detection pattern, since the reference color and the detection color are arranged at the same position in the transport direction, the pattern is hardly affected by the speed unevenness caused by the transfer material transport belt 11.

  As shown in FIG. 8, it can be canceled by setting the pitch of the misregistration detection pattern to an integral multiple of the driving unevenness other than the photosensitive drum 1.

  Measure the color relative to the reference color by fixing the rotation phase of the reference color, detecting the rotation phase of the detected color with respect to the reference color by shifting it by a certain predetermined angle, and repeating the above detection. A waveform as shown in FIG. 9 is obtained with respect to the relationship between the rotation phase and the amplitude of the color, and the optimum phase of each color can be easily determined.

  In FIG. 9, the vertical axis represents the amplitude of the amount of positional deviation of the detected color with respect to the reference color, and the horizontal axis represents the rotational phase of the detected color with respect to the reference color (for the sake of accuracy, at least the driving unevenness of the image carrier is at least It is necessary to obtain a waveform over one period).

The amplitude of the positional deviation amount of the photosensitive drum 1 of the detected color with respect to the positional deviation detection pattern reference color is:
ΔC ₁ (θ) = MAX (a1-bc1, a2-bc2,... A18-bc18, a19-bc19) -MIN (a1-bc1, a2-bc2,... A18-bc18 , A19-bc19) / 2 (Formula 1)
ΔY ₁ (θ) = MAX (a1-by1, a2-by2,... A18-by18, a19-by19) -MIN (a1-by1, a2-by2,... A18-by18 , A19-by19) / 2 (Formula 2)
ΔM ₁ (θ) = MAX (a1−bm1, a2−bm2,... A18−bm18, a19−bm19) −MIN (a1−bm1, a2−bm2,... A18−bm18 , A19-bm19) / 2 (Formula 3)
It is represented by

  Further, there is a method of shortening the time by roughly adjusting the rotational phase of the photosensitive drum 1 of the detected color with respect to the reference color and then finely adjusting the rotational phase.

  In this method, for example, first, a displacement pattern is detected at intervals of 120 ° with respect to the reference phase. Using the detection result, a phase range having a small amplitude of the positional deviation amount is determined. Next, a phase shift pattern is detected by finely changing the phase within the phase range to determine a phase range having a small amplitude of the position shift amount. This operation is repeated, and the phase at which the amplitude of the positional deviation amount is minimized is set as the optimum phase.

  By feeding back the phase detection result to the rotational phase adjustment of the motor 41 so that the optimum phase is obtained, color misregistration can be reduced.

  In the case where there are a plurality of speed irregularities other than those caused by the transfer material conveyance belt 11, the moving average process is performed for the pitch of the line of the misregistration detection pattern as in the following formula, whereby the speed irregularity of the photosensitive drum 1 is performed. Can be easily detected.

ΔC ₁ (θ) = MAX (Average (a1-bc1, a2-bc2, a3-bc3), Average (a2-bc2, a3-bc3, a4-bc4)... Average (a16-bc16, a17-bc17, a18-bc18), Average (a17-bc17, a18-bc18, a19-bc19))-MIN (Average (a1-bc1, a2-bc2, a3-bc3), Average (a2-bc2, a3-bc3, a4- bc4) ... Average (a16-bc16, a17-bc17, a18-bc18) / 2 (Formula 4)
ΔY ₁ (θ) = MAX (Average (a1-by1, a2-by2, a3-by3), Average (a2-by2, a3-by3, a4-by4)... Average (a16-by16, a17-by17, a18-by18), Average (a17-by17, a18-by18, a19-by19))-MIN (Average (a1-by1, a2-by2, a3-by3), Average (a2-by2, a3-by3, a4- by4) ... Average (a16-by16, a17-by17, a18-by18) / 2 (Formula 5)
ΔM ₁ (θ) = MAX (Average (a1-bm1, a2-bm2, a3-bm3), Average (a2-bm2, a3-bm3, a4-bm4)... Average (a16-bm16, a17-bm17, a18-bm18), Average (a17-bm17, a18-bm18, a19-bm19))-MIN (Average (a1-bm1, a2-bm2, a3-bm3), Average (a2-bm2, a3-bm3, a4- bcm4) ... Average (a16-bm16, a17-bm17, a18-bm18) / 2 (Formula 6)

  Hereinafter, the operation of this embodiment will be described. Here, for convenience of explanation, as shown in FIGS. 4 to 6, the positional deviation amount of the detected color with respect to the reference color is calculated from the interval between the positional deviation detection patterns read by the image detection sensor 44, and the positional deviation amount is minimized. The process of acquiring the rotational phase is referred to as “rotational phase acquisition process with minimum positional deviation amount (may be abbreviated as acquisition process)”.

  Motors 41y, 41m, and the like that drive the photoreceptors of the respective colors so that the rotational phase with the minimum positional deviation amount acquired by the acquisition process is obtained by a CPU, which will be described later, which is a central processing unit that performs basic control of the color image forming apparatus. The rotational phases of 41c and 41k are controlled.

  FIG. 10 is a flowchart showing the operation of this embodiment. When replacement of the process cartridge 7 is detected by the replacement detector 28 (step 101, indicated as S101 in the figure, the same applies hereinafter), the process proceeds to step 102 to determine the number of cartridges replaced (step 102). If one is detected, the process proceeds to step 103, and it is determined by using the replacement detector 28 of the process cartridge 7 whether the replaced cartridge is the reference color or the detected color. If the replaced process cartridge has a detected color, the process proceeds to step 105, and the rotational phase detection device 42 detects the rotational phase of the photosensitive drum 1 in the replaced detected color process cartridge with respect to the reference color photosensitive drum. The rotation phase acquisition process with the minimum positional deviation amount is performed only on the exchanged process cartridge.

  When the reference color process cartridge is replaced, a temporary reference color is set. In this embodiment, since the reference color is Bk, the acquisition process may be performed using another process cartridge, for example, magenta, as the reference color (step 105). The case where two process cartridge replacements are detected is the same as the case of one (step 107, step 108). However, when the three are replaced, it is preferable to execute the normal rotational phase acquisition process with the minimum amount of misregistration because the formation and detection time of the misregistration measurement pattern on the endless belt is not shortened (step 109).

  FIG. 11 is a block diagram showing a configuration of a control system including a CPU that performs the processing of FIG. The color image forming apparatus according to this embodiment includes an image processing unit 110, an image memory unit 111, a printer unit 112, an external interface (I / F) processing unit 113, an input / output port (I / O) 114, a CPU 115, and an operation unit 116. ROM 117 and RAM 118 are provided.

  The CPU 115 is a central processing unit that performs basic control of the color image forming apparatus. The CPU 115 is connected to a ROM 117 in which a control program is written, a RAM 118 that provides a work area for the CPU 800 to perform various processes, and an input / output port 114 that inputs and outputs signals by an address bus and a data bus. Yes. Connected to the input / output port 114 are various loads (not shown) such as motors and clutches that drive the mechanisms of the respective parts of the color image forming apparatus, and inputs (not shown) such as sensors for detecting the position of the recording material. ing. The CPU 115 sequentially performs input / output control via the input / output port 114 in accordance with the stored contents (control program) of the ROM 117, thereby executing an image forming operation including the rotational phase acquisition process with the minimum displacement amount.

  The CPU 115 is connected to an operation unit 116 having a display unit for performing various displays and a key input unit for performing various settings. The CPU 115 processes display on the display unit of the operation unit 116 and input from the key input unit. The operator instructs the CPU 115 to switch display of various modes via the key input means of the operation unit 116, and the CPU 115 displays the state of the image forming apparatus and the operation mode setting by key input.

  As described above, if the rotational phase acquisition process with the minimum displacement amount is executed for all the process cartridges, it takes a long time to form and detect a displacement measurement pattern. However, by detecting the loading state of the process cartridge and executing it only on the detected process cartridge, it is possible to reduce the detection time to 2/3 or less without forming an unnecessary pattern on the belt. I can do it.

  Next, a “color image forming apparatus” that is Embodiment 2 will be described with reference to FIG.

  FIG. 12 is a cross-sectional view showing the configuration of the color image forming apparatus. The apparatus according to the present exemplary embodiment uses an intermediate transfer belt, and the display of an exchange detector that detects the exchange of each color cartridge is omitted. The description of the same components as those in the first embodiment is omitted.

  In this embodiment, as shown in FIG. 12, the toner image formed on the surface of the photoconductive drum 1 facing the photoconductive drum 1 serving as a plurality of image carriers arranged in parallel in the horizontal direction is primarily transferred. An intermediate transfer belt (endless belt) 54 serving as an intermediate transfer member is stretched by a driving roller and a driven roller, and a secondary transfer unit 55 is located at a position facing the driven roller across the intermediate transfer belt 54. Has been placed.

  The toner images formed on the respective photosensitive drums 1 in the same manner as in the first embodiment are transferred onto the intermediate transfer belt 54 by the action of transfer means 56a, 56b, 56c, 56d (hereinafter simply referred to as “transfer means 56”). Primary transcription.

  On the other hand, the transfer material S fed from the paper feed cassette 50 by the pickup roller 51 is separated and fed one by one by a separation means (not shown), and then sent to the registration roller pair 53 by the conveying roller pair 52. By the pair 53, the toner image conveyed between the intermediate transfer belt 54 and the secondary transfer means 55 at a predetermined timing and primarily transferred to the intermediate transfer belt 54 by the action of the secondary transfer means 55 is secondarily transferred. The

  The transfer material S onto which the toner image has been transferred is fixed by the fixing unit 21 and then conveyed by the discharge roller pair 57 and discharged onto a discharge tray 24 provided on the upper portion of the apparatus main body 200.

  Also in this embodiment, as in the first embodiment, the misregistration detection pattern for each color is formed on the intermediate transfer belt 54, and the “rotation phase acquisition process with the minimum misalignment amount” is performed in the same manner as in the first embodiment. Thus, the same effect as in the first embodiment can be obtained.

Sectional drawing which shows the principal part structure of the color image forming apparatus which is Example 1. FIG. The figure which shows the principal part structure of the drive part of a photoconductor drum, and a drive transmission part. The figure which shows the principal part structure of the drive part of a photosensitive drum, and a control system The figure which shows the state of the color shift of each color before phase adjustment The figure which shows the state of the signal which detected the phase of the gearwheel which rotationally drives a photosensitive drum The figure which shows the state which eliminated the color shift of each color after phase adjustment of a photoconductive drum The figure which shows the pattern for position shift detection, and its example of arrangement The figure which shows the amount of position shifts with respect to a reference color when driving unevenness other than the photosensitive drum is canceled The figure which shows the change of the position shift amplitude when changing the rotation phase of a photoconductive drum. Flowchart showing processing in the first embodiment. Block diagram showing the configuration of the control system Sectional drawing which shows the principal part structure of the color image forming apparatus which is Example 2. FIG.

Explanation of symbols

1 Photosensitive drum 11 Endless belt 28 Exchange detector 44 Image detection sensor 115 CPU

Claims (3)

Each color cartridge having an image carrier and configured to be replaceable;
Replacement detection means for detecting replacement of the cartridges of the respective colors;
Each color driving means for rotating and driving the image carrier in each color cartridge;
An endless belt that sequentially passes through the cartridges of the respective colors;
Pattern forming means for forming a pattern for detecting displacement on the endless belt;
Pattern detecting means for detecting a pattern for detecting misregistration formed by the pattern forming means;
Processing means for performing processing for obtaining a rotational phase with a minimum amount of displacement based on a detection result of the pattern detection means;
Adjusting means for adjusting the rotational phase of the driving means for each color so as to be the rotational phase with the minimum positional deviation obtained by the processing means;
Control means;
A color image forming apparatus comprising:
The color image forming apparatus according to claim 1, wherein the control unit causes only the cartridge whose replacement is detected by the replacement detection unit to perform a process of acquiring a rotational phase with a minimum displacement amount by the processing unit. A method for adjusting a color image forming apparatus including cartridges of respective colors each having an image carrier and configured to be replaceable,
Detecting the replacement of each color cartridge;
Step B for obtaining a rotational phase with a minimum amount of positional deviation only for the cartridge for which replacement has been detected in Step A;
Adjusting the rotational phase of the image carrier on the basis of the rotational phase with the minimum positional deviation obtained in step B;
A method for adjusting a color image forming apparatus, comprising:   Software for realizing the color image forming apparatus adjustment method according to claim 2.

Images