JPH0550746B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an image forming apparatus that forms multicolor images using electrophotography, and particularly relates to an image forming apparatus that forms a multicolor image using electrophotography, and in particular, an image forming apparatus that forms a plurality of toner images of different colors on an image forming body. The present invention relates to an image forming apparatus that forms images by overlapping them.

[Prior Art] Some conventional multicolor image forming apparatuses sequentially transfer the toner images of each color formed on an image forming body onto a recording paper, and superimpose the toner images of each color on the recording paper. However, such multicolor image forming apparatuses have problems such as the need for a transfer drum, which increases the size of the apparatus, and the transfer misalignment of each color toner image, making it impossible to obtain a clear multicolor image. For example, Japanese Patent Application No. 58-183152,
In the specifications of No. 184381, No. 58-187000, and No. 58-187001, a multicolor image forming apparatus is proposed in which toner images of each color are superimposed on an image forming member. FIG. 7 is a diagram illustrating the configuration of such an image forming apparatus. In the figure, 1 is a drum-shaped image forming body that includes a conductive substrate, an amorphous silicon layer provided thereon, a selenium vapor deposition layer, a resin dispersion layer of cadmium sulfide or zinc oxide, polyvinyl carbazole, anthracene, and polycyclic quinone dye. Alternatively, it consists of a photoconductive photosensitive layer composed of an organic semiconductor layer containing a bisazo dye. The image forming body 1 is rotated in the direction of the arrow, and a charger 2 applies, for example, a positive uniform charge, and then image exposure is performed via a laser device 3 using a type of image information from the original document, and the image forming body 1 is statically exposed. An electric image is formed. This electrostatic image is developed by a developing device 4A to form a corresponding toner image. The image forming body 1 carrying this toner image includes developing devices 4B to 4D, a pre-transfer charger 5, a pre-transfer exposure lamp 6, a transfer device 7, a pre-cleaning static eliminator 9,
It passes through without being affected by the cleaning device 10 or the like and is rotated again to the charger 2.

After being uniformly charged by the charger 2, image exposure is performed based on another type of image information to form an electrostatic image, which is developed by the developer 4B to form a corresponding toner image on the toner image. formed by overlapping.

Similar steps are repeated, and the toner images are developed by the developing device 4C and the developing device 4D, and a multicolor toner image is formed by overlapping these toner images.

This multicolor toner image is made easier to be transferred by the operation of the pre-transfer charger 5 and the pre-transfer exposure lamp 6, which were stopped, and then transferred to the recording paper P by the action of the transfer device 7, and then transferred by the fixing device 8. It is fixed by applying pressure or heating. After the transfer is completed, the image forming body 1 is equipped with a static eliminator 9 consisting of a static eliminator lamp 9a and a corona discharger 9b.
The remaining toner is removed by the cleaning brush 11 of the cleaning device 10, which was released during toner image formation, and is prepared for the next image formation. The developing devices 4A to 4D, etc. installed in this multicolor image forming apparatus are preferably those using a non-contact developing method, and in particular, the developing devices 4B to 4D in the latter stage should not damage the toner images, and This developing device uses a non-contact developing method because it is extremely easy to turn on and off development.

[Problem that the invention seeks to solve]

The image forming apparatus having the above configuration has the advantage that a transfer drum is not required, the apparatus is made smaller, and the image quality is improved without causing transfer misalignment of each color toner image. At this time, the developing device groups 4A, 4B, 4C, and 4D alternately repeat operation and non-operation, and the cleaning device also brings into contact with and releases the image forming body. These causes toner scattering. Furthermore, since the plurality of developing device groups 4A, 4B, 4C, and 4D, which are sources of powder toner, and the cleaning device 10 are arranged in a dispersed manner within the apparatus, the entire apparatus is susceptible to contamination by toner scattering. It is becoming. In particular, since the transfer device 7 is interposed between the developing device group and the cleaning device 10, and the cleaning device 10, which is prone to toner scattering, is located above the transfer device 7, not only toner scattering but also toner leakage and falling may occur. Contamination occurs not only in the transfer device 7 but also in the recording paper feeding system. Furthermore, since the cleaning device 10 is located close to the charger 2, the charging function is degraded, and a clear image cannot be obtained. Although this contamination problem can be alleviated by providing a sufficiently large space between the developing device group and the cleaning device, this increases the circumference of the image forming body, resulting in an increase in the size of the device. It turns out. If the image forming body is large, a problem arises in that the image forming speed is significantly reduced due to the multi-rotation image forming process.

[Means to solve the problem]

The present invention was proposed in view of the above circumstances, and
The purpose of the present invention is to prevent toner contamination, provide clear,
An object of the present invention is to provide an image forming apparatus capable of producing high-quality multicolor images.

The object has an image forming body, a charging means, an exposing means, a plurality of adjacent developing means having toners of different specific colors, a transfer means, and a cleaning means, and the image forming body Image formation in which a latent image is formed by charging by the charging means and exposure by the exposing means, and a toner image of a particular color is developed by a developing means of a particular color corresponding to the latent image among the plurality of adjacent developing means. A multicolor image in which toner images of different specific colors are superimposed on the image forming body to form a multicolor image by repeating the image forming process a plurality of times for each rotation of the image forming body. This is achieved by a multicolor image forming apparatus characterized in that the plurality of adjacent developing means and cleaning means are adjacent to each other around the image forming body.

More specifically, a transfer member (for example, a transfer pole, etc.), an image forming charger, and an image exposure device are not included between the cleaning device and the developing device in the moving direction of the image forming body. composition.

If devices A and B are arranged around the image forming body, "a configuration in which device C is arranged between A and B in the moving direction of the image forming body" means that A is the image forming body. This refers to a configuration in which a certain part of the image forming body faces C before reaching B from A.

The configuration of the present invention will be explained below with reference to FIGS. 1 to 4. FIG. 1 is a cross-sectional view showing an example of the image forming apparatus of the present invention, FIGS. 2 and 3 are cross-sectional views showing other examples of the image forming apparatus of the present invention, and FIG. 4 is a developing device used in the present invention. It is a sectional view of a container. It should be noted that in these figures, the same reference numerals are attached to the same content as in FIG. 7. In FIGS. 1 to 3, reference numeral 1 denotes a drum-shaped image forming body having the photoconductive photosensitive layer, which is rotated in the direction of the arrow, and a scorotron charger 2.
After being uniformly charged, the laser beam scanner 3 performs image exposure based on, for example, a yellow image signal to form an electrostatic image. Thereafter, in FIG. 1, the brush 11 of the cleaning device 10 is moved to a non-contact position with respect to the image forming body to be inactive, and the developing device 4A performs development with, for example, yellow toner to form a yellow toner image.

Next, the image forming body 1 carrying this yellow toner image is transferred to a transfer device 7 consisting of developing devices 4B, 4C, 4D, a pre-transfer charger 5, a pre-transfer exposure lamp 6, a transfer electrode 7a and a separation electrode 7b, a static elimination lamp 9a and It is rotated once in the direction of the arrow with various devices such as the static eliminating device 9 made of the static eliminating electrode 9b inactive, and then recharged by the charger 2. During the next second rotation of the image forming body 1, image exposure with a laser beam is performed based on, for example, a magenta image signal, and an electrostatic image is formed. This electrostatic image is processed by disabling the cleaning device 10 and the various devices other than the developing device 4B, and developing the magenta toner in a non-contact manner using the developing device 4B, and superimposing it on the yellow toner image to form a magenta toner image. do.

Thereafter, recharging, laser beam image exposure,
Developing by the developing devices 4C and 4D is repeated, and a multicolor toner image in which, for example, a cyan toner image and a black toner image are superimposed is formed on the third and fourth rotations of the image forming body 1. Thereafter, the pre-transfer charger 5
After operating the exposure lamp 6 to make it easier to transfer the multicolor toner image, the transfer electrode 7 is operated to transfer the multicolor toner image onto a recording paper P fed from a paper feeder (not shown), and the separation electrode 8 is operated to transfer the multicolor toner image. After separation, the fixing device 8 fixes the toner by heating or applying pressure. Thereafter, after the surface of the image forming body 1 is neutralized by the static eliminating device 9,
During the fifth rotation of the image forming body 1, the image forming body 1 passes through the charger 2 and image exposure 3, which are inactive, and is cleaned by the cleaning brush 11, which is activated by contacting the image forming body 1, and is set for the next image formation. It will be done.

In the image forming apparatus shown in FIG. 1, the transfer device 7 is disposed between the charging device 2 and the developing devices 4A to 4D with respect to the moving direction of the image forming body, and the cleaning device is a source of toner scattering. 10 and developing devices 4A to 4D are arranged together in close proximity to each other below the image forming apparatus, and the transfer device 7, the charger 2,
Since the image exposure device 3 and the like are all arranged above, toner contamination is significantly reduced over the entire area of the image forming apparatus outside these image forming devices. The image forming apparatus shown in FIG. 2 is another example in which the transfer device 7 is disposed between the charger 2 and the cleaning device 10 with respect to the moving direction of the image forming body, and is similar to the case shown in FIG. 1. The cleaning device 10 and the developing devices 4A to 4D, which are the sources of toner scattering, are arranged below the image forming device, and the transfer device 7, charger 2, and image exposure device 3, which are the sources of toner contamination, form the image. Since they are all arranged above the apparatus, toner contamination of not only each image forming device but also the entire area of the image forming apparatus is reduced as in the case of FIG. The image forming process in FIG. 2 is the same as that in FIG.
Charging, image exposure, and development are repeated on the image forming body to form a multicolor toner image in which toner images are superimposed. Thereafter, the pre-transfer charger 5 and the exposure lamp 6 are activated to make it easier to transfer the multicolor toner image, and then the toner image passes through the inactive charger 2 and the image exposure device 3, and is supplied from a paper feeder (not shown). recording paper P
The transfer electrode 7 is activated to transfer the image, the separation electrode 8 is activated to separate the image, and then the fixing device 8 fixes the image by applying heat or pressure. Thereafter, the surface of the image forming body 1 is neutralized by the static eliminating device 9, and then cleaned by the cleaning brush 11 which is activated by contacting the image forming body 1, and is prepared for the next image formation.

FIG. 3 shows still another example of the image forming apparatus shown in FIG. 1, and the configuration in which each device is arranged is the same as that shown in FIG. Intermediate transfer roll 12a and recording paper transfer roll 12
A transfer device 12 consisting of b is used. That is, by four rotations of the image forming member 1, a multicolor toner image formed by overlapping yellow, magenta, cyan, and black toner images, for example, is transferred to the adhesive intermediate transfer roll 12a, and this is transferred to the recording paper. The image is transferred and fixed onto the recording paper P under heat and pressure from the transfer roll 12b, and the other configurations are exactly the same as in the case of FIG. 2. Therefore, as in the case of FIG. 2, toner contamination is reduced in each image forming device and throughout the apparatus.

Next, a developing device suitable for the image forming apparatus of the present invention,
The developing conditions, developer, etc. will be explained below.
As the developing method using each developing device of the image forming apparatus of the present invention, either regular development or reversal development can be performed, and the developing method, conditions, equipment, etc. are not particularly limited, but as described above, In order to avoid disturbing the toner image that has already been formed during development, it is preferable to use a developing method called non-contact development in which a developer layer containing toner does not come into direct contact with the surface of the image forming member.

FIG. 4 shows an example of a developing device suitable for performing the above-mentioned non-contact development. 24 is a layer thickness regulating blade that regulates the thickness of the developer layer formed on the developing sleeve 22; 25 is the developing sleeve 2;
2 a scraper blade that removes the developer layer after development from above; 26 a stirring rotor that stirs the developer in the developer reservoir 27; 28 a toner hopper; and 29 a surface that replenishes toner from the toner hopper 28 to the developer reservoir 27. A toner replenishment roller 30 has a recess into which toner enters, and a toner replenishment roller 30 applies a bias voltage that may have a vibrational component to the developing sleeve 22 via a protective resistor 31 to prevent toner movement between the developing sleeve 22 and the image forming body 1. The figure shows that the developing sleeve 22 and the magnet 23 rotate in the directions of the arrows, but even if the developing sleeve 22 is fixed, the magnet The body 23 may be fixed, or the developing sleeve 22 and the magnet body 23 may rotate in the same direction. Magnet body 23
When the magnetic pole is fixed, usually, in order to make the magnetic flux density of the magnetic pole corresponding to the image forming body 1 larger than the magnetic flux density of other magnetic poles, the magnetization is strengthened or two magnetic poles of the same or different polarity are attached thereto. In some cases, the magnetic poles of the two are placed close to each other.

In such a developing device, the magnetic pole of the magnet body 23 is usually
It is magnetized to a magnetic flux density of 500 to 1500 Gauss,
The developer in the developer reservoir 27 is attracted to the surface of the developing sleeve 22 by the magnetic force, and the thickness of the adsorbed developer is regulated by the layer thickness regulating blade 24 to form a developer layer. The developer layer is the image forming body 1
The surface of the developing sleeve 22 develops the electrostatic image on the image forming body 1 in the developing area facing the surface of the image forming body 1 by moving in the same direction or in the opposite direction to the direction of the rotation arrow. The developer sleeve 22 is removed from the surface of the developer sleeve 22 and returned to the developer reservoir 27.

As the developer used in the method of the present invention, a non-magnetic two-component developer, a non-magnetic one-component developer, and a so-called one-component magnetic developer that uses only a magnetic toner containing a magnetic substance can be used. A so-called so-called toner consisting of a mixture of a non-magnetic toner and a magnetic carrier can obtain a toner with a clear color without the need to include a black or brown magnetic substance in the toner, and the charging of the toner can be easily controlled. It is preferable to use a two-component developer. In particular, when magnetic carriers are used in resins such as styrene resins, vinyl resins, ethylene resins, rosin-modified resins, acrylic resins, polyamide resins, epoxy resins, and polyester resins, triiron tetroxide, γ-ferric oxide, and Products containing dispersed particles of ferromagnetic or paramagnetic materials such as chromium, manganese oxide, ferrite, manganese-copper alloy, or materials whose surfaces are coated with the above-mentioned resins. consisting of a resistivity of 10 ⁸ Ωcm or more, preferably 10 ¹³ Ωcm
The above insulating carrier is preferred. If this resistivity is low, when a bias voltage is applied to the developing sleeve 22, charges may be injected into the carrier particles, making it easier for the carrier particles to adhere to the surface of the image forming body. The problem arises that no voltage is applied. In particular, if the carrier adheres to the image forming body 1, it will adversely affect the tone of the color image.

The resistivity was measured by placing particles in a container with a cross-sectional area of 0.50 cm ² and tapping them, then applying a load of 1 kg/cm ² on the packed particles, and comparing the electrode that also served as the load and the bottom electrode. This value is obtained by reading the current value when applying a voltage that creates an electric field of 1000 V/cm between the two.

Furthermore, if the average particle size of the carrier is less than 5 μm, the magnetization will be too weak, and if it exceeds 50 μm, the image will not be improved, breakdown or discharge will easily occur, and high voltage will not be able to be applied. The diameter is preferably 5 μm or more and 50 μm or less, and if necessary, a suitable amount of a flow agent such as hydrophobic silica is added as an additive.

As for the toners, the cyan one has copper phthalocyanine added instead of black carbon black, the magenta one has the same polytungstophosphoric acid added, and the yellow one has the same benzidine derivative added. Additions are used. However, the toner is not limited to such colored toners using pigments, and colored toners using dyes may also be used, and it goes without saying that a charge control agent or the like may be added as necessary. The toner preferably has an average particle size of 1 to 20 μm,
In addition, the average charge amount is 3 to 300μc/g, especially 5 to 300μc/g.
100 μc/g is preferred. When the average particle size of toner is less than 1 μm, it becomes difficult to separate from the carrier, and when it exceeds 20 μm, the resolution of the image decreases. Note that the average particle size is a weight average particle size and is measured using a Coulter Counter (manufactured by Coulter Inc.).

When a developer made of a mixture of an insulating carrier and toner as described above is used, the bias voltage applied to the developing sleeve 22 shown in FIG. Settings can be easily performed without fear of leaks. In order to more effectively control the development movement of the toner by applying such a bias voltage, the toner may also contain a magnetic material such as that used in magnetic carriers to the extent that color clarity is not impaired. It's okay.

The above is the structure of the developing device and developer preferably used in the method of the present invention, but the present invention is not limited to this.
58-116553 to 116554 may be used, and more preferably, the developing device and developer described in Japanese Patent Application No. 58-116554 filed earlier by the applicant of the present application may be used.
No. 57446, No. 58-96900 to No. 96903, No. 58-97973
No. 58-23829, No. 58-238296, using the developer method and developer described in each specification.
In non-contact development using a one-component developer or a two-component developer, that is, when there is no potential difference between the surface of the image forming body 1 and the developing sleeve, the thickness of the developer layer formed on the developing sleeve in the developing area is It is preferable to perform development under conditions set so that the gap is thinner than the gap between the surface of the formed body and the developing sleeve.

〔Example〕

Examples of the present invention will be described below, but the embodiments of the present invention are not limited thereto.

Example 1 FIG. 1, FIG. 4, FIG. 5, and FIG. 6 are diagrams explaining this example, and FIG. 5 shows the reference image formed on the image forming body and the formation position of the image. In the plan view,
In FIG. 5, the drum-shaped image forming body of FIG. 1 is shown as being developed in a plane.
FIG. 6 is a timing chart when forming a multicolor image using the image forming apparatus shown in FIG.

The image forming body 1 incorporated in the image forming apparatus shown in FIG. 1 is formed by providing an amorphous silicon layer on the surface of an aluminum drum, and has a diameter of 120 mm. This image forming member 1 is rotated in the direction of the arrow at a speed of just over 3 seconds per rotation, and four color toner images of yellow, magenta, cyan, and black are superimposed and formed in four rotations. First, in the first rotation, the image forming body 1
Uniform charging Vy of +600V by corona charger 2
is given, yellow information is written thereon by the semiconductor laser beam scanner 3, and a yellow reference latent image Ey ₁ and a yellow image, which are color image information, are read by an image reading device in synchronization with the rotation of the image forming body. A latent image Ey ₂ is formed.
These latent images are reversely developed with positive yellow toner by the developing device 4A with the cleaning device 10 inactive, and a yellow reference toner image Dy ₁ and a yellow image toner image Dy ₂ are formed.

The developing device 4A is made of magnetite and resin, containing 70 wt% of magnetite dispersed, with an average particle size of 30 μm, magnetization of 30 emu/g, and resistivity of 10 ¹⁴ Ωem.
The above carrier and a non-magnetic toner with an average particle size of 10 μm and an average charge amount of 25 μc/g are prepared by adding 10 parts by weight of a benzidine derivative and other positive charge control agents as a yellow pigment to 100 parts by weight of the toner to a styrene-acrylic resin. The ratio of developer to toner is
It was used under conditions of 20wt%. In addition, as a developing device, the developing device shown in FIG.
At 100 rpm, the magnetic flux density of the N and S magnetic poles of the magnet body 23 is
1000 Gauss, rotation speed in the direction of the arrow is 1000 rpm, developer layer thickness in the developing area is 0.6 mm, developing sleeve 22
The gap between the image forming body 1 and the developing sleeve 22 is 0.8 mm.
Non-contact development was performed by applying a superimposed voltage of +400V DC voltage and 1.5KHz, 1000V AC voltage.
Note that in order to make the developing devices 4B to 4D inactive while the developing device 4A is developing an electrostatic image, the sleeve 22 can be disconnected from the power source 30 to be in a floating state, grounded, or only the DC component can be turned off. This is achieved by applying or actively applying a DC bias voltage of opposite polarity to the charging of the image forming member 1 to the developing sleeve 22, and among these means, it is preferable to apply a DC bias voltage.

After the second rotation of the image forming body 1, uniform positive charges Vm, Vc, and Vb are sequentially applied in the same manner except that the formation position of the latent image is different as shown in FIGS. 5 and 6, and the laser Reference latent image created by beam writing
Em ₁ , Ec ₁ , Eb ₁ and image latent images Em ₂ , Ec ₂ , Eb ₂ are formed. These latent images are sequentially processed by the developing units 4B and 4.
C and 4D to form a superimposed multicolor toner image.

That is, while the pre-transfer exposure lamp 1 is applied to the surface of the image forming body 1 that has been subjected to the first development, the second rotation is also performed without using the static eliminator 9 and the cleaning device 10. + with charger 2
After performing a second charge to 600V, a second image exposure is performed again using the same laser beam scanner at the same spot density so that the spot positions do not overlap, and then a second development of magenta toner is performed using the developing unit 4B. I went there. Similarly, the third development of cyan toner by the developer 4C and the fourth development of black toner by the developer 4D were repeated.

In the development using each of the above-mentioned developing devices, the voltage of the DC bias component or the AC bias component applied to the developing sleeve 22 is adjusted appropriately according to changes in the surface potential of the image forming body 1, development characteristics, color reproducibility, etc. The amplitude, frequency, application time, etc. of the toner image are changed, or the density of each color toner image is adjusted. The developing units 4B to 4D also use the non-contact developing unit shown in FIG. 4, similar to the developing unit 4A, and the coloring agent of the toner in the developer contained therein is polytungstophosphoric acid as a magenta pigment in the developing unit 4B. , developer 4
Development was the same except that copper phthalocyanine was used as the cyan pigment in C and carbon black was used as the black pigment in developer 4D.

Furthermore, other pigments and dyes can be used as colorants.

After the fourth development is performed and a four-color image is formed on the image forming body 1, it is made easier to be transferred by the pre-transfer charger 5 and the pre-transfer exposure lamp 6,
The image is transferred onto the recording medium P by the transfer device 7 and fixed by the fixing device 8 . Image forming body 1 to which a color image has been transferred
is neutralized by the static eliminator 9, residual toner is removed from the surface by contact with the fur brush of the cleaning device 10, and the surface on which the color image has been formed is completely removed when it passes through the cleaning device 10. One cycle of color image recording is completed. In this embodiment, a multicolor toner image in which toner images of each color are superimposed is formed based on the reference latent image and feedback information from the reference toner image, so that a multicolor image with excellent reproducibility is formed. The cleaning device 10 and the developing devices 4A to 4D, which are sources of scattering, are arranged together below the image forming device, and the transfer device 7, charger 2, image exposure device 3, etc. that are subject to toner contamination are also arranged together. Since the image forming apparatus is disposed above the image forming apparatus, toner contamination of these devices is reduced and toner contamination of the entire area of the image forming apparatus is eliminated, resulting in a clear multicolor image.

Example 2 This example is different from Example 1 in that the image forming apparatus shown in FIG. 2 is used instead of the image forming apparatus shown in FIG. 1 of Example 1. In this embodiment as well, as in the first embodiment, the cleaning device 10 and the developing devices 4A to 4D are arranged below the image forming apparatus, so that toner contamination is reduced. It is important that through Examples 1 and 2, the paper feed device, which was conventionally located below the image forming apparatus and had extremely poor conditions for toner contamination, can now be placed in a more advantageous position. be.

〔Effect of the invention〕

As described above, according to the apparatus of the present invention, toner contamination within the apparatus can be easily prevented by concentrating toner contamination sources in one place, and the copying speed is not significantly affected. Furthermore, it is possible to eliminate transfer misalignment of toner images without increasing the size of the device compared to conventional devices. With these features, it is possible to print clearly, with copying speeds that are almost the same size as conventional machines.
This has the effect that a high quality multicolor image can be obtained.

[Brief explanation of drawings]

FIG. 1 is a cross-sectional view showing an example of the image forming apparatus of the present invention, FIGS. 2 and 3 are cross-sectional views showing other examples of the image forming apparatus of the present invention, and FIG. 4 is a cross-sectional view showing an example of the image forming apparatus of the present invention. FIG. 5 is a cross-sectional view of the developing device incorporated in the image forming apparatus, and a plan view showing the positions where the reference toner image and the image toner image of the image forming body are formed. Further, FIG. 6 is a timing chart when forming a multicolor image using the image forming apparatus of the present invention, and FIG. 7 is a sectional view of a conventional image forming apparatus. 1... Image forming body, 2... Charger, 3... Image exposure device, 4A to 4D... Developer, 5... Pre-transfer charger, 6... Pre-transfer exposure lamp, 7... Transfer device,
7a... Transfer electrode, 7b... Separation electrode, 8... Fixing device, 9... Static elimination device, 9a... Static elimination lamp, 9
b... Static elimination electrode, 10... Cleaning device, 1
1...Fur brush, 12...Transfer device using a transfer drum, 12a...Intermediate transfer roll, 12b...
...Transfer paper transfer roll.

Claims (1)

[Scope of Claims] 1. An image forming member comprising: an image forming member, a charging means, an exposing means, a plurality of adjacent developing means having toners of different specific colors, a transfer means, and a cleaning means; A latent image is formed on the forming body by charging by the charging means and exposure by the exposing means, and a toner image of a particular color is formed by a developing means of a particular color corresponding to the latent image among the plurality of adjacent developing means. By performing an image forming step of developing and repeating the image forming step multiple times for each rotation of the image forming body, toner images of different specific colors are superimposed on the image forming body to form a multicolor image. A multicolor image forming apparatus characterized in that the plurality of adjacent developing means and cleaning means are adjacent to each other in the periphery of the image forming body.