JP2001117460A - Color image forming device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an image forming device capable of prolonging the life of a photoreceptor drum and a transferring belt while keeping the cleaning property of the transferring belt. SOLUTION: In this color image forming device of tandem type forming each image of yellow, magenta, cyanogens and black toners on a photoreceptor drum and successively transferring the images by the transferring means for each color to a material to be transferred carried by an electrostatic carrying type, when inversely transferring the toner on the transferring belt to the photoreceptor drum and cleaning it by a cleaner removing a transfer residual toner, the surface speed difference between the photoreceptor drum to which the toner of the transferring belt is transferred inversely and the photoreceptor drum to which the toner of the transferring belt is not transferred inversely is >=3%.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] The present invention relates to a color image forming apparatus.

[0002]

2. Description of the Related Art In recent years, with the spread of electrophotographic color image forming apparatuses, there has been an increasing demand for faster color output in addition to a demand for recording quality of color images. To meet this demand, several proposals have been made for image forming methods. Among them, tandem type yellow (hereinafter referred to as Y) toner, magenta (hereinafter referred to as M) toner, and cyan (hereinafter referred to as C) Each image is formed on a drum-shaped image carrier by a toner and a black (hereinafter referred to as Bk) toner, and is sequentially transferred to a transfer material conveyed by an electrostatic conveyance belt by respective transfer means. There is a color image forming method in which the image is fixed last.

FIG. 4 shows a conventional tandem type color image forming apparatus.
FIG. 3 is a side sectional view showing an example of the arrangement. 14 is a transfer bell
With rollers 13a, 13b, 13c, 13d
The transfer material P is transported by being stretched and rotating in the direction of the arrow. Transcription
The configuration of the belt is 50 to 300 μm in thickness and volume resistance.
Resistance 10⁹ -10¹⁶Ω · cm PVdF (poly
Vinylidene chloride), polyamide, polyimide, PET
Trees such as ethylene terephthalate) and polycarbonate
Fat material and thickness 0.5-2mm, volume resistivity 10 ⁹ -10
¹⁶Ω · cm chloroprene rubber, EPDM
Len-prolepin-diene terpolymer), NBR (d
Rubber materials such as tolylbutadiene rubber) and urethane rubber
Used.

In some cases, these materials are not
Bonn, ZnO, SnO_Two , TiO _Two Conductive filler such as
And the volume resistivity is 10⁷ -10¹¹ Ω · cm
It may be adjusted to the extent.

Next, 1Y is an OP as an image carrier for Y.
A C photosensitive drum, a drum unit 10Y including a cleaner 9Y and a charging roller 2Y, and a developing unit 8Y including a developing sleeve 5Y, a non-magnetic one-component developer 3Y, a developer applying roller 6Y, and a developer applying blade 7Y. A process cartridge is configured.

Reference numeral 11Y denotes an exposure device which comprises a scanner unit or an LED array for scanning a laser beam with a polygon mirror, and irradiates a photosensitive beam 1Y with a scanning beam 12Y modulated based on an image signal. A transfer roller 4Y is disposed on the opposite side of the photosensitive drum 1Y across the transfer belt 14, and is connected to a transfer bias power supply 22Y. Then, by applying a transfer bias at a transfer nip formed by the photosensitive drum 1Y and the transfer roller 4Y on the transfer material P conveyed by the transfer belt 14, the toner image on the photosensitive drum 1Y is electrostatically transferred to the transfer material. I do.

As a transfer roller, for example, an EPD in which a metal core is adjusted to a volume resistivity of 10 ⁵ to 10 ⁸ Ω · cm
A configuration covered with an elastic body such as M, urethane rubber, or NBR can be used. The above is the configuration of the Y station. Note that this configuration is the same for stations of other colors, and the components of the stations are M ^* . M and C are ^* . C, Bk
^* . Bk ( ^* is the sign of the corresponding member).

When the image forming operation is started, the photosensitive drums 1Y, 1M, 1C, and 1Bk, the transfer belt 14, and the like start rotating in a direction indicated by an arrow at a predetermined process speed. The photosensitive drum 1Y is uniformly charged to a negative polarity by the charging roller 2Y, and subsequently, an electrostatic latent image according to image information is formed by the scanning beam 12Y from the exposure device 11Y.

The toner 3Y in the developing unit 8Y is charged to a negative polarity by a developer applying blade 7Y and is applied to the developing sleeve 5Y. Then, when the photosensitive drum 1Y rotates and the electrostatic latent image formed on the photosensitive drum 1Y reaches the developing sleeve 5Y, the electrostatic latent image is visualized by a negative toner by a reversal developing method, and is formed on the photosensitive drum 1Y. Is formed with a Y toner image.

On the other hand, the transfer material P loaded on the transfer material cassette 15 is picked up by a half-month paper feed roller 16, separated one by one by a sheet material separation roller 17, and is transferred to a registration roller 19 by a conveyance roller 18. Conveyed. Then, the transfer material P is transported by the registration roller 19 in synchronization with the toner image on the photosensitive drum 1Y.

The transfer material P is electrostatically attracted to the transfer belt 14 by applying a voltage between the attraction roller 20 and the roller 13a, and then a positive transfer bias is applied to the toner image on the photosensitive drum 1Y. The image is transferred onto the transfer material P by the transfer roller 4Y. Then, in synchronization with the transfer of the transfer material P by the transfer belt 14, M, C, B
k toner image formation and transfer to the transfer material P are performed,
The transfer material P to which the Y, M, C, and Bk toner images have been transferred is separated from the transfer belt 14 and sent to the fixing device 21, where the toner image on the transfer material P is melted and fixed to obtain a color image. Further, the toner remaining on the photosensitive drums 1Y, 1M, 1C and 1Bk is cleaned by cleaning devices 9Y, 9M, 9C and 9Bk such as fur brushes and blade means.

[0012]

In the above-described color image forming apparatus, since the transfer of the toner image is always performed on the transfer material, the transfer belt is not stained with the toner. However, when there is fogging toner, when the image is formed while the transfer material is not conveyed due to paper jam, or when the size of the image is different from the designated transfer material. The image is directly transferred onto the transfer belt.

In order to control the image density by the color image forming apparatus main body, a toner image may be formed on the transfer belt on a trial basis. In such a case, the cleaning of the transfer belt is not performed unless the transfer belt is cleaned. This will cause back contamination of the transfer material on which the image is transferred.

Therefore, a method of cleaning the toner on the transfer belt by using a blade, a brush, or the like is considered. However, this method causes abrasion on the transfer belt, making it impossible to perform normal transfer and causing an image defect. become.
Further, a waste toner container for storing waste toner collected by a blade, a brush, or the like is newly required, and if the space of the color image forming apparatus main body is pressed down, it will be increased.

An object of the present invention is to provide an image forming apparatus capable of effectively cleaning toner on a transfer belt without adding a new member in view of the above situation. .

[0016]

A first configuration of a color image forming apparatus for realizing the object of the invention according to the present application is to visualize an electrostatic latent image on an image carrier with a developer of a developing unit, A plurality of color image forming means for removing the developer remaining on the image carrier by the image carrier cleaning means, and a transfer material for transferring the plurality of color developer images on the respective image carriers. A transfer material carrier, a plurality of transfer means provided corresponding to each image carrier for transferring a developer image on the image carrier to a transfer material carried on the transfer material carrier; A transfer material carrier cleaning means for reversely transferring the developer on the transfer carrier to any of the plurality of image carriers and removing the developer by the image carrier cleaning means; , Transfer material carrier cleaning During degree, among the plurality of image bearing members,
At least one of the image carriers for reversely transferring the developer charged to the normal charging polarity is operated at a surface moving speed different from that of the transfer material carrier.

A second configuration of the color image forming apparatus for realizing the object of the invention according to the present application is the above-described first configuration, wherein the transfer material carrier cleaning means is provided with a different surface movement from the transfer material carrier. The present invention is characterized in that the image carrier, which is operated at a speed, is replaced with another image carrier each time cleaning is performed a predetermined number of times.

A third configuration of the color image forming apparatus for realizing the object of the invention according to the present application is the above-described first or second configuration, wherein the image is operated at a surface moving speed different from that of the transfer material carrier. The carrier has a speed difference of 3% or more from the surface moving speed of the transfer material carrier.

A fourth configuration of the color image forming apparatus for realizing the object of the invention according to the present application is to visualize an electrostatic latent image on an image carrier with a developer of a developing means and to form the electrostatic latent image on the image carrier. A multi-color image forming unit that removes the remaining developer by an image carrier cleaning unit; an intermediate transfer body on which the multi-color developer images on each of the image carriers are transferred; A plurality of first transfer means provided corresponding to each of the image carriers for transferring a developer image on the body; and transferring a plurality of color developer images on the intermediate transfer body to a transfer agent. A second transfer unit, and an intermediate transfer body cleaning unit that reversely transfers the developer on the intermediate transfer body to any of the plurality of image carriers and removes the developer by the image carrier cleaning unit; The intermediate transfer member cleaning means includes an intermediate transfer member. During the leaning process, of the plurality of image carriers, at least one of the image carriers that reversely transfers the developer charged to the normal charging polarity is operated at a surface moving speed different from that of the intermediate transfer body. It is characterized by.

A fifth configuration of the color image forming apparatus for realizing the object of the present invention according to the present application is the fourth configuration, wherein the intermediate transfer member cleaning means has a surface moving speed different from that of the intermediate transfer member. Each time the cleaning is performed a predetermined number of times, the image carrier to be operated is replaced with another image carrier.

A sixth aspect of the color image forming apparatus for realizing the object of the present invention according to the present invention is the color image forming apparatus according to the fourth or fifth aspect, wherein the image bearing member operates at a surface moving speed different from that of the intermediate transfer member. The transfer speed of the intermediate transfer member is 3
% Or more.

[0022]

DESCRIPTION OF THE PREFERRED EMBODIMENTS (First Embodiment) A color image forming apparatus according to a first embodiment of the present invention will be described below with reference to the accompanying drawings.

FIG. 1 is a schematic view of a color image forming apparatus to which the present invention is applied. Components having the same structure and operation as those in FIG. 4 are denoted by the same reference numerals and description thereof is omitted.

In FIG. 1, a transfer bias power supply 23Y,
23Bk can generate a positive bias having the same polarity as that during normal image formation, and the transfer bias power supplies 23M and 23C can generate both positive and negative biases. In this embodiment, the rotation speed of the photosensitive drum 1M is variable.

In this configuration, after a print job is completed, after image density control is completed, after a jam is cleared, when the power is turned on, etc.
At a predetermined transfer belt cleaning timing, the control unit (not shown) controls the transfer rollers 4Y of the first and fourth colors.
A positive bias of +1.5 kV is applied to 4Bk from the transfer bias power supplies 23Y and 23Bk, while the second and third biases are applied.
A transfer bias power supply 23 is provided to the transfer rollers 4M and 4C for the color.
A negative bias of -1.5 kV is applied from M and 23C.

The toner on the transfer belt 14 is mainly a negatively charged toner having a regular charging polarity, but there are also toners which have been inverted to a positive polarity having the opposite charging polarity and non-polarized toners. Exists. Therefore, first, a positive bias, which is the polarity at the time of transfer, is applied to the transfer roller 4Y of the first color,
The toner that has become positive is reversely transferred to the photosensitive drum 1Y and collected by the cleaner 9Y.
The toner on the transfer belt 14 is charged to a negative polarity, which is a normal charging polarity.

Next, at the transfer position of the second color, by applying a negative bias from the transfer roller 4M, the negative toner passing through the first color is reversely transferred to the photosensitive drum 1M of the second color. And collect with a cleaner 9M. Here, the toner that cannot be collected has a positive polarity, a non-polarity, or a negative polarity. Therefore, at the transfer position of the third color, a negative bias is applied from the transfer roller 4C to apply the negative bias. Of the toner not collected in the second color, the negative polarity toner is replaced with the photosensitive drum 1C.
And collected by the cleaner 9C. At this time,
Toner that is positive, non-polar, or negative but has not been reverse-transferred to the photosensitive drum 1C due to a small charge amount is charged to a positive polarity. Therefore, by applying a positive bias to the transfer roller 4Bk in the fourth color, the positive toner remaining on the transfer belt 14 is removed from the photosensitive drum 1B.
k and is recovered by a cleaner 9Bk. Thus, the cleaning of the toner on the transfer belt 14 is completed.

The process speed of the color image forming apparatus in this embodiment is 100 mm / sec, and the transfer belt 14 and the similar belt 14 at the time of cleaning the transfer belt are moving at the same belt peripheral speed.

Here, the peripheral speed of the photosensitive drum 1M for collecting the negatively charged toner having the normal charging polarity was set to be 10% faster than the peripheral speed of the transfer belt. Generally, when a peripheral speed difference is provided between the photosensitive drum and the transfer belt, the toner on the transfer belt is forcibly moved by a frictional force generated by the peripheral speed difference,
The effect of the Van der Waals force between the transfer belt and the toner is reduced, and the toner is more strongly affected by the electric field, so that the cleaning ability is dramatically improved. Normally, the toner on the transfer belt 14 is predominantly negative polarity toner having a normal charging polarity, and therefore, a peripheral speed difference is provided only to the photosensitive drum 1M which collects the toner first.
However, the peripheral speed of the transfer belt and the photosensitive drums 1Y, 1C, 1
The drum peripheral speeds of Bk do not completely match due to variations in the mechanical accuracy of the components. Further, a slight difference in peripheral speed may be provided in order to enhance the stability of transferability and transportability. In practice, there is a difference in peripheral speed of 0 to 3%, but it is regarded as constant speed. Normal,
If a peripheral speed is applied between the photosensitive drum and the transfer belt, the photosensitive drum and the transfer belt are rubbed against each other, so that their surfaces are scraped off. Therefore, while increasing the cleaning performance by providing a peripheral speed difference only to the photosensitive drum that collects the largest amount of toner, the peripheral speed difference is not provided to other photosensitive drums that can be sufficiently collected without providing the peripheral speed difference. Thus, the photosensitive drum and the transfer belt were prevented from being cut off more than necessary.

As described above, the bias applied to the transfer rollers 4Y to 4Bk during the cleaning of the transfer belt has a positive polarity and a negative polarity, and further, the photosensitive member for recovering the toner charged to the negative polarity having the regular charging polarity. By making only the peripheral speed of the drum 1M different from the peripheral speed of the transfer belt, reliable cleaning can be performed while the transfer belt 14 makes one rotation.

The combination for applying the positive and negative transfer biases in the transfer belt cleaning of the present embodiment is not limited to this, but may be other combinations.
At least one configuration in which a negative transfer bias is applied and a peripheral speed difference is provided to the photosensitive drum is required.

(Second Embodiment) A color image forming apparatus according to a second embodiment of the present invention will be described below with reference to the accompanying drawings.

FIG. 2 is a schematic view of an image forming apparatus in which a color to which the present invention is applied. Components having the same structure and operation as those in FIG. 1 are denoted by the same reference numerals and description thereof is omitted. In the present embodiment, both positive and negative biases can be generated for the transfer bias power supplies 24Y and 24M, and the rotation speeds of the photosensitive drums 1Y and 1M are made variable.

In this configuration, when a predetermined transfer belt cleaning timing is reached, for example, after the end of a print job, image density control, jam processing, power-on, etc., first, the transfer rollers 4Y and 4Bk of the first and fourth colors are applied. Positive bias from transfer bias power supplies 24Y and 24Bk + 1.
5 kV is applied, while a negative bias of -1.5 kV is applied to the transfer rollers 4M and 4C of the second and third colors from the transfer bias power supplies 24M and 24C.

At this time, the photosensitive drums 1Y, 1M, 1C, 1
Bk is charged to a normal charging potential of -600V. The peripheral speeds of the photosensitive drums of the first, third and fourth colors are equal to the peripheral speed of the transfer belt, and the peripheral speed of the photosensitive drum of the second color is 10% of the peripheral speed of the transfer belt. Perform transfer belt cleaning at high speed. The transfer belt cleaning described above is referred to as a first cleaning mode.

On the other hand, the following second cleaning mode is also prepared.

That is, the transfer rollers 4 of the second and fourth colors
M and 4Bk are supplied with a bias of +1.5 V of normal polarity from the transfer bias power supplies 24M and 24Bk,
A transfer bias power supply 24 is provided to the transfer rollers 4Y and 4C for the eyes.
A negative bias of -1.5 V is applied from Y and 24C.

At this time, the photosensitive drums 1Y, 1M, 1C, 1
Bk is charged to a normal charging potential of -600V. The peripheral speeds of the photosensitive drums of the second, third, and fourth colors are equal to the peripheral speed of the transfer belt, and the peripheral speed of the photosensitive drum of the first color is 10% of the peripheral speed of the transfer belt. Perform transfer belt cleaning at high speed.

In this embodiment, if the cleaning of the transfer belt 14 performed at a certain timing is in the first cleaning mode, the second cleaning mode is performed in the next transfer belt cleaning. Change modes alternately.

In the first embodiment, the photosensitive drum for providing the peripheral speed difference is determined to be the second color. However, as in the second embodiment, the photosensitive drum for providing the peripheral speed difference is changed for each transfer belt cleaning. By switching to, it is possible to prevent only a specific drum from being scraped, and to extend the life of the photosensitive drum.

The switching of the cleaning mode may be performed not every transfer belt cleaning but every predetermined number of transfer belt cleanings. Further, all the transfer bias power supplies 4Y to 4Bk can generate both positive and negative biases, and the rotation speeds of all the photosensitive drums 1Y to 1Bk can be varied to provide a peripheral speed difference between the third and fourth color photosensitive drums. It is preferable to provide third and fourth cleaning modes in which the first to fourth cleaning modes are sequentially performed so that the scraping amount of the photosensitive drum can be further uniformly dispersed.

(Third Embodiment) FIG. 3 shows a third embodiment.

The third embodiment relates to a color image forming apparatus using an intermediate transfer member. FIG. 3 is an overall schematic view of the image forming apparatus according to the third embodiment, and has the same configuration as that of FIG. The members having the same function are denoted by the same reference numerals, and description thereof is omitted.

In this embodiment, a toner image of each color is transferred to an endlessly rotating intermediate transfer body 25, and a full-curler toner image on the intermediate transfer body 25 is transferred to a transfer material. 25 is a resin material such as PVdF (polyvinylidene fluoride), polyamide, polyimide, PET (polyethylene terephthalate), polycarbonate or the like having a thickness of 50 to 300 μm and a volume resistivity of about 10 ⁹ to 10 ¹⁶ Ω · cm; ~ 2mm, low volume efficiency 10 ⁹ -10
Rubber materials such as chloroprene rubber, EPDM (ethylene-propylene-diene terpolymer), NBR (nitrile butadiene rubber), urethane rubber and the like of about ¹⁶ Ω · cm are used.

In some cases, conductive fillers such as carbon, ZnO, SnO ₂ , and TiO ₂ may be dispersed in these materials to adjust the volume resistivity to about 10 ⁷ to 10 ¹¹ Ω · cm. is there. And this is the drive roller 13
The driven roller 13b is stretched by the transfer opposing roller 13c.

The transfer material P is fed from the paper feed cassette 15 to the feed roller 17, the transport roller pair 18, and the registration roller pair 1 in synchronization with the formation of the color image on the intermediate transfer body 25.
At 9 the sheet is conveyed to the transfer section.

In the transfer section, a transfer roller 26 is provided with the intermediate transfer body 2.
5, the transfer material P is applied with a transfer bias when the transfer material P passes between the intermediate transfer body 25 and the transfer roller 26, so that the toner image temporarily transferred to the intermediate transfer body 25 is transferred to the transfer material P.
Is transferred to the fixing device 21, and the toner image is fused and fixed to obtain a color image.

In the above configuration, each photosensitive drum 1Y, 1Y
M, 1C, 1Bk drum peripheral speeds and transfer rollers 4Y, 4Y
The biases of M, 4C, and 4Bk are set in the same manner as in the first embodiment.

In general, in a color image forming apparatus of the intermediate transfer member type, a toner image is formed on the intermediate transfer member 25, so that when the surface of the intermediate transfer member is scraped by rubbing and toner fusion occurs or rubbing scratches increase, the intermediate transfer is performed. An image is not properly formed on the body, and the image quality may be greatly impaired. Therefore, as described above, by making the peripheral speed of the photosensitive drums of the first and third colors equal to the peripheral speed of the intermediate transfer belt, it is possible to prevent the photosensitive drum and the intermediate transfer from being cut off more than necessary. The service life of the drum and the intermediate transfer member can be extended.

In the present embodiment, the same settings as in the first embodiment are made, but the same settings as in the second embodiment are of course also possible.

The image forming apparatus according to the present invention is not limited to the above embodiment, but can be variously changed within the scope of the invention. That is, the transfer member is not limited to the transfer roller, but may be a transfer blade, a transfer brush, a corona charger, or the like, and the order of colors may be arbitrary. Then, the transfer bias and the charging potential of the photosensitive drum may be changed, and the four colors may have different values. In the above embodiments, the peripheral speed difference is set to 10%, but the optimum value of the peripheral speed difference changes depending on the process speed, the photosensitive drum diameter, the bias setting, and the like. In the above embodiments, the peripheral speed difference is set such that the drum peripheral speed of the photosensitive drum is higher than the belt peripheral speed. However, the peripheral speed difference may be provided by making the peripheral speed lower than the belt peripheral speed. Further, the peripheral speed difference may be set to a different value for each location. Further, in each of the above-described embodiments, two photosensitive drums for uniform toner polarity and two photosensitive drums for collecting toner are used. Other combinations such as three photosensitive drums may be used.

[0052]

As described above, according to the present invention, in the cleaning of the developer such as the toner on the transfer material carrier and the intermediate transfer member of the tandem type color image forming apparatus, the developer is mainly reversed. A peripheral speed difference is provided between the transfer material carrier and the intermediate transfer member only on the photosensitive drum as an image carrier for copying and collecting toner, so that the photosensitive drum, the transfer material carrier, and the intermediate transfer member are maintained while maintaining the cleaning performance. Prolong the life of the body.

[Brief description of the drawings]

FIG. 1 is a schematic view of an image forming apparatus according to a first embodiment of the present invention.

FIG. 2 is a schematic diagram of an image forming apparatus according to a second embodiment of the present invention.

FIG. 3 is a schematic diagram of an image forming apparatus according to a third embodiment of the present invention.

FIG. 4 is a longitudinal sectional view illustrating a schematic configuration of a conventional image forming apparatus.

[Explanation of symbols]

 1Y, 1M, 1C, 1Bk: Photosensitive drums 2Y, 2M, 2C, 2Bk: Charging rollers 3Y, 3M, 3C, 3M, 3Bk: Developers 4Y, 4M, 4C, 4Bk: Transfer rollers 5Y, 5M, 5C, 5Bk ... Developing sleeve 9Y, 9M, 9C, 9Bk ... Cleaning blade 11Y, 11M, 11C, 11Bk ... Exposure device 12Y, 12M, 12C, 12Bk ... Scanning beam 14 ... Transfer belt 19 ... Registration roller 20 ... Attraction roller 21 ... Fixing device 22Y 22M, 22C, 22Bk transfer bias power supply 23Y, 23M, 23C, 23Bk transfer bias power supply 24Y, 24M, 24C, 24Bk transfer bias power supply 25 intermediate transfer body 26 transfer roller

Claims (6)

[Claims] 1. A multi-color image forming means for visualizing an electrostatic latent image on an image carrier with a developer of a developing means and removing the developer remaining on the image carrier by an image carrier cleaning means. And a transfer material carrier that conveys a transfer material to transfer a plurality of color developer images on the image carriers,
A plurality of transfer means provided for each image carrier to transfer a developer image on the image carrier to a transfer material carried on the transfer material carrier; Transfer material carrier cleaning means for transferring the agent back to any of the plurality of image carriers and removing the agent by the image carrier cleaning means, wherein the transfer material carrier cleaning means comprises During the cleaning process, at least one of the plurality of image carriers that reversely transfers the developer charged to the normal charging polarity is operated at a surface moving speed different from that of the transfer material carrier. A color image forming apparatus, comprising: 2. The transfer material carrier cleaning means,
Each time the image carrier that is operated at a different surface moving speed from the transfer material carrier is cleaned a predetermined number of times,
2. The image forming apparatus according to claim 1, wherein said image carrier is replaced with another image carrier.
3. The color image forming apparatus according to 1. 3. The image carrier that is operated at a surface moving speed different from that of the transfer material carrier has a speed difference of 3% or more from the surface moving speed of the transfer material carrier. Or the color image forming apparatus according to 2. 4. A multi-color image forming means for visualizing an electrostatic latent image on an image carrier with a developer of a developing means and removing the developer remaining on the image carrier by an image carrier cleaning means. And an intermediate transfer member on which a plurality of color developer images on each image carrier are transferred, and each of the image carriers for transferring the developer image on the image carrier to the intermediate transfer member. A plurality of first transfer means, a second transfer means for transferring a plurality of color developer images on the intermediate transfer body to a transfer material, and a plurality of first transfer means provided on the intermediate transfer body. An intermediate transfer member cleaning unit for performing reverse transfer to any one of the image carriers and removing the intermediate transfer member by the image carrier cleaning unit; Charged to the normal charge polarity of the body A color image forming apparatus, wherein at least one of the image carriers to which the developed developer is reversely transferred is operated at a surface moving speed different from that of the intermediate transfer member. 5. The image forming apparatus according to claim 1, wherein the intermediate transfer body cleaning unit replaces the image carrier, which is operated at a surface moving speed different from that of the intermediate transfer body, with another image carrier each time cleaning is performed a predetermined number of times. The color image forming apparatus according to claim 4, wherein: 6. The image carrier which operates at a surface moving speed different from that of the intermediate transfer member has a speed difference of 3% or more from the surface moving speed of the intermediate transfer member. 3. The color image forming apparatus according to 1.