JP2008242077A - Color image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a color image forming apparatus which meets the need for miniaturization and higher processing speed of the apparatus, and also completely suppressing out of color registration. <P>SOLUTION: The image forming apparatus 100 is four-cycle type color image forming apparatus, and has an intermediate transfer belt 7, and forms a color image by superposing a toner image on the intermediate transfer belt 7. The image forming apparatus 100 acquires a color shift amount from a reference position of the toner image in predetermined timing. Namely, a color shift patch is formed on the intermediate transfer belt 7, a cleaning blade 61 is operated to press-contact with/separate from the intermediate transfer belt 7 while the color shift patch is primarily transferred thereto, and the color shift amount is acquired based on a detection signal of a color shift detection sensor 78. Furthermore, when the color shift amount exceeds a predetermined threshold, toner to which an external additive is added is supplied to the intermediate transfer belt 7. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to an electrophotographic color image forming apparatus. More specifically, the present invention relates to a color image forming apparatus that forms a color image by superimposing a plurality of toner images on an endless intermediate transfer member.

  In an electrophotographic color image forming apparatus, a rigid intermediate transfer belt is provided, and toner images of each color of C (cyan), M (magenta), Y (yellow), and K (black) are superimposed on the intermediate transfer belt. What forms an image is known. For example, a system (4 cycle system) that has a CMYK development device for each color and forms a full-color image by superimposing the toner images of each color on the intermediate transfer belt by rotating the intermediate transfer belt four times has been put into practical use. ing.

  In a four-cycle image forming apparatus that superimposes a toner image on an intermediate transfer belt, the intermediate transfer belt is rotatably suspended by a plurality of rollers, and the cleaning member and the secondary transfer member can be pressed against and separated from the intermediate transfer belt. Is arranged. That is, the cleaning member or the like retracts from the intermediate transfer belt while the toner image is superimposed on the intermediate transfer belt, and presses against the intermediate transfer belt when the superimposed toner image is secondarily transferred to a sheet or the like. .

  However, when the cleaning member or the like is pressed against and separated from the intermediate transfer belt, the deflection of the intermediate transfer belt changes due to the impact at the moment when the cleaning member contacts or leaves. As a result, the moving speed of the intermediate transfer belt changes and color misregistration occurs between the colors. Therefore, as in the image forming apparatus disclosed in Patent Document 1, for example, each member is arranged so as not to press and separate the cleaning member or the like during the primary transfer. In addition, for example, as in the image forming apparatus disclosed in Patent Document 2, a device is provided to reduce the impact when the cleaning member or the like is pressed and separated.

An external additive composed of zinc stearate or calcium stearate is added to the toner constituting the developer. When such toner enters the gap between the cleaning blade and the intermediate transfer belt, the external additive functions as a lubricant, reducing the friction coefficient μ between the two. As a result, the impact of the cleaning member is reduced. Therefore, for example, Patent Document 3 discloses an image forming apparatus that lowers the coefficient of friction μ by supplying toner onto an intermediate transfer belt after printing a predetermined number of sheets.
Japanese Patent Laid-Open No. 10-48967 Japanese Patent Laid-Open No. 10-326068 JP 2002-244386 A

  However, the above-described conventional color image forming apparatus has the following problems. That is, in recent years, there has been a demand for a more compact apparatus and a higher process speed, and it is required to shorten the circumference of the intermediate transfer belt and increase the rotational speed. For this reason, it is difficult to dispose the cleaning member or the like as in Patent Document 1 so that the press-contact separation timing and the primary transfer are shifted. Further, in order to meet the recent demand for higher image quality, even if a member for reducing the impact as in Patent Document 2 is provided, color misregistration cannot be sufficiently suppressed.

  In particular, the coefficient of friction μ between the cleaning blade and the intermediate transfer belt increases during continuous printing of images with a low printing rate or in a high humidity environment. And, as the friction coefficient μ increases, the color shift tends to deteriorate. Patent Document 3 discloses a technique for reducing the friction coefficient μ by supplying toner, and it can be expected to suppress color misregistration by reducing the friction coefficient μ. However, only the control based on the number of printed sheets as in Patent Document 2 cannot cope with the friction coefficient μ that changes in accordance with the contents of printing or environmental changes. For this reason, the color shift cannot be sufficiently suppressed.

  Further, if toner is supplied periodically as in Patent Document 3, the toner is supplied even when the lubricant is sufficiently supplied. That is, toner may be wasted. This is not limited to the control based on the number of printed sheets, but can occur even with control based on the printing rate and humidity.

  The present invention has been made to solve the problems of the conventional color image forming apparatus. That is, an object of the present invention is to provide a color image forming apparatus that can cope with downsizing of the apparatus and increase in the process speed, and sufficiently suppresses color misregistration.

  In order to solve this problem, a color image forming apparatus includes a plurality of developing devices, a primary image carrier subjected to development by color by the developing device, and a primary transfer of a toner image from the primary image carrier. A secondary image carrier, a secondary transfer member provided so as to be capable of being pressed and separated from the secondary image carrier, and secondarily transferring a toner image on the secondary image carrier to a transfer material; and a secondary image carrier And a cleaning member that removes toner on the secondary image carrier, and forms a monochromatic toner image on the primary image carrier. A color image forming apparatus for forming a color image by superimposing a plurality of toner images on a toner image, wherein a positional deviation amount of the toner image transferred on the secondary image carrier in the traveling direction of the secondary image carrier is determined. It has a color misregistration detection unit to detect and forms a test image at a predetermined timing Then, the cleaning member is pressed and separated during the primary transfer of the test image, the color misregistration detection unit acquires the misregistration amount of the test image, and when the misregistration amount exceeds the threshold value, the secondary image A lubricant that reduces the coefficient of friction with the cleaning member is supplied onto the carrier.

  The color image forming apparatus of the present invention forms a toner image on a primary image carrier (photosensitive drum or the like), and primarily transfers the toner image onto a secondary image carrier (intermediate transfer belt or the like). A color image forming apparatus that superimposes toner images of respective colors and secondarily transfers the superimposed color image onto a transfer target. For this reason, it is necessary to separate the secondary transfer member that performs the secondary transfer and the cleaning member that collects the transfer residual toner after the secondary transfer from the secondary image carrier while the toner images are superimposed. Therefore, the secondary transfer member and the cleaning member are provided so as to be capable of being pressed and separated from the secondary image carrier.

  The color image forming apparatus of the present invention acquires the amount of positional deviation of the toner image on the secondary image carrier at a predetermined timing. That is, a test image is formed on the secondary image carrier, the cleaning member is pressed and separated during the primary transfer of the test image, and the misregistration detection unit acquires the amount of misregistration at that time. The developing device for forming the test image is not particularly limited, but is preferably a developing device having the largest amount of remaining toner or a developing device having the lowest usage frequency. In the pressing / separating operation, the pressing may be performed first or the separation may be performed first depending on the contact state with the secondary image carrier such as the cleaning member. The predetermined timing for detecting misregistration includes the secondary image carrier and the cleaning member when warming up, when it is determined that the humidity is low, or when the toner consumption or the number of prints exceeds a predetermined value. The timing at which the coefficient of friction is considered to increase is appropriate.

  If the acquired positional deviation amount exceeds a predetermined threshold value, the cleaning member is brought into contact with the secondary image carrier, and the secondary transfer member is separated and lubricated on the secondary image carrier. Supply agent. By supplying the lubricant, the lubricant adheres to the tip of the cleaning member. As a result, the friction coefficient μ is reduced, and the amount of displacement is reduced.

  Further, in the color image forming apparatus of the present invention, even when the cleaning member or the like is pressed or separated during the image transfer, the toner image positional deviation amount is suppressed within an allowable range. Therefore, it is not necessary to perform the press-contact separation operation of the cleaning member or the like between the images, and the degree of freedom in designing the secondary image carrier is great. Therefore, it is possible to cope with downsizing of the apparatus and higher process speed.

  In the color image forming apparatus of the present invention, it is determined whether or not to supply the lubricant based on the result of the color misregistration detection unit. In other words, the lubricant is not supplied if the positional deviation amount is within the allowable range. Therefore, excessive supply of lubricant is suppressed. Therefore, the lubricant can be used effectively without wastefully supplying the lubricant.

  Further, the lubricant of the present invention is preferably added to the toner, and is preferably supplied together with the toner from at least one of the developing devices. That is, by supplying the lubricant added to the toner, there is no need to provide a dedicated supply device for the lubricant. Therefore, the image forming apparatus main body can be made more compact.

  When the lubricant is supplied, it is better that the lubricant is supplied from the developing device having the largest amount of toner in the developing device. That is, by using a toner that is less frequently used, it is possible to consume the toner in a well-balanced manner and to improve the toner replacement cycle. Further, when supplying the lubricant, the lubricant may be supplied from the developing device having the largest amount of lubricant added in the developing device. That is, the friction coefficient can be reduced earlier by selecting such a toner.

  According to the present invention, there is provided a color image forming apparatus that can cope with downsizing of the apparatus and increase in process speed, and sufficiently suppresses color misregistration.

  DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments embodying the present invention will be described below in detail with reference to the accompanying drawings. In the present embodiment, the present invention is applied to a four-cycle type color printer having a rotating rack that accommodates four developing devices.

  As shown in FIG. 1, the image forming apparatus 100 according to this embodiment includes a photosensitive drum 1 that is an image carrier, and uniformly charges the surface of the photosensitive drum 1 around the photosensitive drum 1. A charging device 2, an exposure device 3 for forming an electrostatic latent image on the surface of the photosensitive drum 1, and an electrostatic latent image on the photosensitive drum 1 for making a visible image (toner image). The developing unit 4, a primary transfer roller 5 for transferring the toner image on the photosensitive drum 1, and a cleaning blade 6 for removing the transfer residual toner from the photosensitive drum 1, the rotational direction of the photosensitive drum 1 It is provided along (arrow A in FIG. 1).

  Further, the image forming apparatus 100 includes an intermediate transfer belt 7 on which the toner image on the photosensitive drum 1 is primarily transferred. Further, on the paper transport path, a paper feed cassette 81 for storing paper before image transfer, a timing roller 71 for adjusting the paper transport timing to the transfer position, and a toner image on the intermediate transfer belt 7 are secondarily transferred. Secondary transfer roller 72 for fixing, fixing device 9 for fixing the transferred toner image on the paper, paper discharge tray 82 for storing the paper after the image transfer, and temperature and humidity for detecting temperature and humidity A sensor 8 is provided.

  The intermediate transfer belt 7 is an endless belt, and is stretched by a primary transfer roller 5, a secondary transfer counter roller 73, a tension roller 74, a cleaner counter roller 75, and a primary transfer winding roller 76. It runs in the direction of arrow B in FIG. 1 by the rotational driving force of the next transfer counter roller 73. Further, a positional deviation amount of the toner image on the intermediate transfer belt 7 with respect to the traveling direction of the intermediate transfer belt 7 on the downstream side of the primary transfer position and on the upstream side of the secondary transfer position in the moving direction of the intermediate transfer belt 7. A color misregistration detection sensor 78 for detecting (hereinafter referred to as “color misregistration amount”) is provided. In addition, a cleaning device 60 for removing transfer residual toner on the intermediate transfer belt 7 is provided downstream of the secondary transfer position and upstream of the primary transfer position in the moving direction of the intermediate transfer belt 7. Yes. Further, a position detection sensor 51 for measuring the primary transfer timing is provided downstream of the cleaning position and upstream of the primary transfer position in the moving direction of the intermediate transfer belt 7. The cleaning device 60 includes a cleaning blade 61 that is in pressure contact with the intermediate transfer belt 7, and the cleaning blade 61 can be pressed against and separated from the intermediate transfer belt 7. Further, the secondary transfer roller 72 can also be pressed against and separated from the intermediate transfer belt 7.

  The developing unit 4 accommodates four developing devices and includes a rotating rack 40 that can rotate in the direction of arrow C in FIG. Specifically, the rotating rack 40 includes developing devices 4Y, 4M, 4C, and 4K corresponding to yellow, magenta, cyan, and black colors. When each developing device performs development, the rotating rack 40 is rotated so that each developing device faces the photosensitive drum 1. The rotating rack 40 rotates 90 degrees for each color development, and forms a full-color image in one round (4 cycles).

  Next, a color image forming operation by the image forming apparatus 100 will be briefly described. The image forming apparatus 100 starts operation by receiving a start signal, image data, and the like. Then, the image forming apparatus 100 creates image data corresponding to each color. The photosensitive drum 1 is rotationally driven in the direction of arrow A in FIG. Then, it is uniformly charged by the charging roller at a position facing the charging device 2. Next, exposure is performed by the exposure device 3, and an electrostatic latent image based on the image data is formed on the surface.

  Next, when the electrostatic latent image reaches the position of the developing unit 4, the charged toner is caused by the electric field formed between the developing bias voltage applied to the developing roller and the electrostatic latent image on the photosensitive drum 1. It moves to the photosensitive drum 1 and the electrostatic latent image is developed with toner. The toner image on the photosensitive drum 1 is transferred to the intermediate transfer belt 7 by the primary transfer roller 5. The residual transfer toner remaining on the photosensitive drum 1 without being transferred to the intermediate transfer belt 7 by the primary transfer roller 5 is scraped off by the cleaning blade 6. Thereby, the image formation for one color is completed. Then, the carousel 40 is rotated 90 degrees in preparation for the next color image formation. These operations are performed in the order of yellow, magenta, cyan, and black, and the four color toner images are superimposed on the intermediate transfer belt 7 to form a full color image. The toner images are superposed by using a detection hole (not shown) provided in the intermediate transfer belt 7 and a position detection sensor 51 to match the writing start timing on the photosensitive drum 1.

  On the other hand, the sheet S that has been transported through the sheet transport path starting from the sheet cassette 8 is timed to the image leading edge position by the timing roller 71, and between the intermediate transfer belt 7 and the secondary transfer roller 72. Be transported. The color image on the intermediate transfer belt 7 is transferred onto the paper S by the secondary transfer roller 72. Further, the sheet S holding the transferred toner image is further conveyed, and heat and pressure are applied by the fixing device 9, whereby the toner image is fixed on the sheet S. Thereby, the color image formation for one sheet is completed.

  Note that the cleaning blade 61 and the secondary transfer roller 72 are separated from the intermediate transfer belt 7 during the formation of a full-color image. The secondary transfer roller 72 is pressed against the intermediate transfer belt 7 before the sheet passes, and is separated again after the transfer. The cleaning blade 61 is pressed against the intermediate transfer belt 7 before the transfer residual toner of the full-color image passes, and is separated again after the transfer residual toner is removed.

  Next, a color misregistration detection method and suppression method will be described in detail. In the image forming apparatus 100 of this embodiment, the cleaning blade 61 or the secondary transfer roller 72 is pressed or separated even during the primary transfer of the toner image. Specifically, in the color printer 100 of the present embodiment, the above-described pressure contact and separation operation is not performed during primary transfer of magenta and cyan. On the other hand, during the primary transfer of yellow, the separating operation of the cleaning blade 61 and the secondary transfer roller 72 is performed. During the primary transfer of black, the pressing operation of the cleaning blade 61 and the secondary transfer roller 72 is performed.

  FIG. 2 shows an example of color misregistration amounts for the second and subsequent sheets during continuous printing. The horizontal axis in FIG. 2 means the position [mm] on the intermediate transfer belt 7 corresponding to the A4T size paper, and the 0 mm position in the drawing is the rear end in the paper printing direction. Further, the vertical axis in FIG. 2 represents the amount of misregistration [mm] of each color with respect to the traveling direction of the intermediate transfer belt 7 when a magenta toner image is used as a reference.

  As shown in FIG. 2, during the primary transfer of yellow, the secondary transfer roller 72 and the cleaning blade 61 are separated from the intermediate transfer belt 7. For this reason, color misregistration occurs as compared with magenta in which no separation operation is performed. Further, during the primary transfer of black, the secondary transfer roller 72 and the cleaning blade 61 are in pressure contact with the intermediate transfer belt 7. For this reason, color misregistration occurs as compared with magenta in which no pressure contact operation is performed. In particular, it can be seen that the amount of color misregistration at the trailing edge of the sheet on which the pressure contact and separation of the cleaning blade 61 acts is large.

  FIG. 3 shows the relationship between the torque of the driving roller 73 when the cleaning blade 61 is pressed and the color misregistration amount of the toner image on the intermediate transfer belt 7. The greater the torque when the cleaning blade 61 is pressed, that is, the greater the frictional resistance of the cleaning blade 61, the greater the difference in resistance during separation. As a result, the change in the deflection amount of the intermediate transfer belt 7 is also large, and the color misregistration amount is large. Therefore, it can be seen that the amount of color misregistration can be kept low by reducing the frictional resistance of the cleaning blade 61.

  FIG. 4 shows the relationship between the friction coefficient μ of the cleaning blade 61 and the environment (humidity / temperature). In this embodiment, urethane rubber is used as the cleaning blade 61, and the friction coefficient μ increases in a high humidity environment. In addition, as a condition for increasing the friction coefficient μ, there is a reduction in lubricant due to continuous printing of images with a low printing rate.

  In the color printer 100 of the present embodiment, the amount of color misregistration is reduced by the procedure of the flowchart shown in FIG. 5 based on the data in FIGS. First, it is determined whether it is time to detect the amount of color misregistration (S1). The timing of detecting the color misregistration amount is, for example, when the warm-up, when the humidity sensor 8 determines that the humidity is high, or when the accumulated toner consumption or the number of printed sheets from the previous color misregistration detection exceeds the threshold. Or when a predetermined number of images with a low printing rate are continuously printed. That is, the color misregistration amount is detected when the friction coefficient μ increases and the rotational driving torque of the intermediate transfer belt 7 may increase.

  Next, the color misregistration amount is acquired (S2). There are several methods for obtaining the color misregistration amount. In this embodiment, a virtual reference line is provided on the intermediate transfer belt 7 using a signal from the position detection sensor 51 used for color matching as a trigger. Then, as shown in FIG. 6, a test pattern (hereinafter referred to as “color shift patch”) for detecting color shift is printed on the intermediate transfer belt 7. Any developing device may be used for printing the color misregistration patch. In this embodiment, the developing device having the largest amount of toner is assumed. That is, by using a toner that is less frequently used, it is possible to consume the toner in a well-balanced manner and to improve the toner replacement cycle. During printing of the color misregistration patch, the cleaning blade 61 is separated and pressed. Then, a color shift amount from the virtual reference line is detected by a color shift detection sensor 78 which is a reflective sensor.

As shown in FIG. 6, the color misalignment of the cleaning blade 61 when pressed and separated is in a position lagging behind the virtual reference line in the traveling direction of the intermediate transfer belt 7 when separated, and in the traveling direction of the intermediate transfer belt 7 when pressed. A color misalignment patch is printed at a position advanced from the virtual reference line. In this embodiment, a value obtained by adding the average value of the deviation amounts at the time of separation and the average value of the deviation amounts at the time of press contact expressed by the following formula (1) is defined as the color deviation amount.
Color misregistration amount = | average (deviation amounts 1, 2, 3) | + | average (deviation amounts 4, 5, 6) | (1)

  Next, it is determined whether or not the detected color misregistration amount exceeds a threshold value (S3). If the color misregistration amount exceeds the threshold (S3: YES), the lubricant is supplied onto the intermediate transfer belt 7 (S4). At this time, as shown in FIG. 7, the cleaning blade 61 is brought into pressure contact, and the secondary transfer roller 72 is separated. As a result, the lubricant is conveyed to the position of the cleaning blade 61, and the lubricant adheres to the tip of the cleaning blade 61. Therefore, the friction coefficient μ between the cleaning blade 61 and the intermediate transfer belt 7 is reduced. The supply of the lubricant is repeated until the color misregistration amount becomes a threshold value or less (S2 to S4). As a result, the color misregistration amount is controlled to be within the allowable range. In other words, even if the rotational driving torque of the intermediate transfer belt 7 may increase, the lubricant is not supplied if the actually detected color misregistration amount is less than or equal to the threshold value.

  In this embodiment, an external additive added to the toner is used as a lubricant. That is, when supplying the lubricant, the toner is supplied onto the intermediate transfer belt 7. As an external additive, zinc stearate or calcium stearate is applicable. The toner supplied as the lubricant may have any color, and in this embodiment, the toner having the largest remaining amount is used. As a result, the toner can be consumed in a well-balanced manner according to the usage status of the user. However, the present invention is not limited to this, and a toner having the largest amount of external additive may be used. Further, the toner supply amount may be adjusted according to the color misregistration amount. As a result, a more appropriate amount of toner can be used and toner waste is reduced.

  In addition, the lubricant is not necessarily an external additive added to the toner, and a dedicated device for supplying the lubricant may be provided. This makes it possible to effectively use resources without wasting toner. On the other hand, by using an external additive added to the toner as the lubricant, the lubricant can be supplied without providing a dedicated device, and the image forming apparatus main body can be made compact or the cost can be reduced.

  As described above in detail, the image forming apparatus 100 according to the present embodiment acquires the color misregistration amount at a predetermined timing. That is, the color misregistration patch is transferred onto the intermediate transfer belt 7, the cleaning blade 61 is pressed and separated during the primary transfer of the color misregistration patch, and the color misregistration amount is acquired based on the detection signal of the color misregistration detection sensor 78. is doing. Further, when the color misregistration amount exceeds a predetermined threshold, toner is supplied onto the intermediate transfer belt 7. By supplying the toner, the toner, that is, the external additive added to the toner adheres to the tip of the cleaning blade 61. As a result, the friction coefficient is reduced, and the displacement of the cleaning blade 61 when pressed and separated is suppressed within an allowable range.

  Further, in the image forming apparatus 100 of this embodiment, even when the cleaning blade 61 is pressed or separated during the primary transfer of the toner image, the color misregistration amount is suppressed within an allowable range. For this reason, it is not necessary to perform the pressing and separating operation of the cleaning blade 61 between images, and the degree of freedom in designing the intermediate transfer belt 7 and the like is great. Therefore, it is possible to cope with downsizing of the image forming apparatus and high process speed. Therefore, a color image forming apparatus that can cope with downsizing of the apparatus and high process speed and sufficiently suppresses color misregistration has been realized.

  Further, in the image forming apparatus 100 of this embodiment, it is determined whether or not to supply the lubricant based on the result of the color misregistration detection sensor 78. Therefore, excessive supply of lubricant is suppressed. Therefore, resources can be used effectively without wastefully supplying the lubricant.

  Note that this embodiment is merely an example, and does not limit the present invention. Therefore, the present invention can naturally be improved and modified in various ways without departing from the gist thereof. For example, in the embodiment, the present invention is applied to a printer, but the present invention is not limited to this. That is, even a copying machine, scanner, FAX, word processor, or the like can be applied as long as it has a rotating rack that can accommodate a plurality of developing devices. Further, the number of developing devices accommodated in the rotating rack is not limited to four. Further, the developing device is not limited to the rotating rack, and a developing device may be juxtaposed on the photosensitive drum.

1 is a diagram illustrating a schematic configuration of a color printer according to an embodiment. FIG. 6 is a diagram illustrating a relationship between a color misregistration amount and a position on an intermediate transfer belt after the second sheet during continuous printing. It is a figure which shows the relationship between the amount of color shifts, and the torque at the time of cleaning member press-contact. It is a figure which shows the relationship between the friction coefficient of a cleaning member, and an environment. It is a flowchart which shows a color shift suppression procedure. It is a figure which shows the procedure which detects the amount of color shift. FIG. 4 is a diagram showing a pressure contact and separation state of a cleaning blade and a secondary transfer roller when a lubricant is supplied.

Explanation of symbols

1 Photosensitive drum (primary image carrier)
4 Developing units 4Y, 4M, 4C, 4K Developing device 61 Cleaning blade (cleaning member)
7 Intermediate transfer belt (secondary image carrier)
72 Secondary transfer roller (secondary transfer member)
78 Color shift detection sensor (color shift detection unit)
8. Temperature / humidity sensor 100 Image forming device

Claims (4)

A plurality of developing devices; a primary image carrier subjected to development by color by the developing device; a secondary image carrier receiving primary transfer of a toner image from the primary image carrier; and the secondary image carrier. A secondary transfer member that secondarily transfers the toner image on the secondary image carrier to a transfer material, and a pressure contact and separation with respect to the secondary image carrier. A cleaning member that removes toner on the secondary image carrier, forms a single color toner image on the primary image carrier, and superimposes a plurality of toner images on the secondary image carrier In a color image forming apparatus that forms a color image by combining them,
A color misregistration detection unit for detecting a positional deviation amount of the toner image transferred onto the secondary image carrier in the traveling direction of the secondary image carrier;
A test image is formed at a predetermined timing, the cleaning member is pressed and separated during the primary transfer of the test image, and the misregistration detection unit acquires the misregistration amount of the test image, and the misregistration amount. A color image forming apparatus, wherein a lubricant that reduces a friction coefficient with the cleaning member is supplied onto the secondary image carrier when the value exceeds a threshold value. The color image forming apparatus according to claim 1,
The color image forming apparatus, wherein the lubricant is added to the toner and is supplied together with the toner from at least one of the developing devices. The color image forming apparatus according to claim 2,
When supplying the lubricant, the color image forming apparatus is characterized in that the lubricant is supplied from the developing device having the largest amount of toner in the developing device. The color image forming apparatus according to claim 2,
When supplying the lubricant, the color image forming apparatus is characterized in that the lubricant is supplied from a developing device having the largest amount of lubricant in the developing device.