JPH1124367A - Image forming device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an image forming device capable of preventing the occurrence of toner scattering at the time of multiple-transferring a toner image of plural colors on a transfer material. SOLUTION: When toner images t1, t2 and t3 formed on the image carrier 12 is transferred on the transfer material P superimposedly in layers, in order to prevent the scattering of the toner image t1 on the upper most layer liable to cause the toner scattering, for instance, the spherical toner with high sphericity is used for the outermost layer toner image t1, and the monolithic toner with low sphericity degree is used for the lower layer toner images t2 and t3.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a color image forming apparatus used in a color printer or a color copying machine using an electrophotographic system.

[0002]

2. Description of the Related Art Conventionally, in a color image forming apparatus such as a color printer or a color copying machine using an electrophotographic system, a toner image of a plurality of colors is formed on one or a plurality of image carriers, and the toner image is formed on a transfer member. 2. Description of the Related Art A color image forming apparatus is used in which a color image is formed by sequentially superimposing and transferring a color image.

FIG. 12 is a schematic configuration diagram showing an example of a conventional color image forming apparatus. FIG. 12 shows an example in which the electrostatic latent image forming apparatus 1a, the image carrier 1b, and the rotary type developing machine 1c for four colors are built in, for example, black (K), yellow (Y),
An image forming unit 1 for forming magenta (M) and cyan (C) toner images, a transfer / conveyance roll 2 for conveying a recording sheet P to which a toner image formed on the image carrier 1b is transferred, and a recording sheet P 1 shows a paper image peeling device 4 that peels off a sheet from a transfer / transport roll 2, and a color image forming apparatus provided with a fixing device 5. In this color image forming apparatus, toner images of black (K), yellow (Y), magenta (M), and cyan (C) formed by the image forming unit 1 are sequentially superimposed on the recording paper P. After the transfer, the recording paper P is peeled from the transfer / conveyance roll 2 by the paper peeling device 4, and further, the fixing is performed to form a color image.

FIG. 13 is a schematic configuration diagram showing another example of a conventional color image forming apparatus. FIG. 13 shows toner images of, for example, black (K), yellow (Y), magenta (M), and cyan (C) in which an electrostatic latent image forming apparatus, an image carrier, and a developing device are respectively incorporated. Image forming unit 6 for forming
a, 6b, 6c, 6d, a transfer / transport belt 2 ', on which a recording sheet P for receiving the transfer of the toner image of each color formed on the image carrier of each of the image forming units is placed and circulated; A color image forming apparatus including a paper peeling device 4 for peeling P from the transfer / conveying belt 2 ′ and a fixing device 5 is shown. In this color image forming apparatus,
Image forming units 6a, 6b, 6 corresponding to the above colors
After the toner images formed by c and 6d are sequentially superimposed and transferred onto the transfer / transport roll 2, the recording sheet P is peeled off from the transfer / transport roll 2 by the sheet peeling device 4 and further fixed. A color image is formed.

FIG. 14 is a schematic diagram showing another example of a conventional color image forming apparatus. FIG. 14 shows a toner image of, for example, black (K), yellow (Y), magenta (M), and cyan (C) in which an electrostatic latent image forming apparatus, an image carrier, and a developing device are incorporated. Image forming unit 6 to be formed
a, 6b, 6c, 6d, an intermediate transfer drum 7 as a transfer receiving body for receiving each color toner image formed on the image carrier of each image forming unit, and four colors formed on the intermediate transfer drum 7 1 shows a color image forming apparatus provided with a secondary transfer device 8 and a fixing device 5 for secondary transfer of the toner image on the recording paper P. In this color image forming apparatus, each color toner image formed on the image carrier of each image forming unit is sequentially superimposed and transferred onto the intermediate transfer drum 7, and a plurality of color toner images formed on the intermediate transfer drum 7 are transferred. The image is secondarily transferred to the recording paper P at once.

FIG. 15 is a schematic diagram showing another example of a conventional color image forming apparatus. In FIG. 15, an intermediate transfer belt 9 is used as a transfer object instead of the intermediate transfer drum 7 in the color image forming apparatus shown in FIG.

[0007]

However, in the above-described conventional color image forming apparatus, when the toner images of the respective colors formed on the image carrier are successively superimposed and transferred onto the transfer-receiving member, blurring occurs. In some cases, a toner scattering phenomenon called “toner scattering” is caused to deteriorate the image quality, or the inside of the apparatus is stained with toner. In particular, when the pile height (stacking height) of the toner image is high or when the amount of charge of the toner is relatively large, the repulsive force between the toners exceeds the toner adhesion force due to the transfer electric field. Easy to scatter.

FIG. 16 is a view showing a toner scattering phenomenon when a toner image on an image carrier is transferred to a transfer-receiving member. As shown in FIG. 16, when the toner image T on the image carrier 1b is transferred onto the transfer target 3 (for example, recording paper),
When the pile height H of the toner image T is high, the transfer electric field weakens as the toner image T moves away from the transfer nip portion N, and when the repulsive force between the toners exceeds the toner adhesion force due to the transfer electric field, the toner image T The toner t of the uppermost layer easily jumps out of the toner image T.

In the case where a spherical toner having a high fluidity is used to increase the transfer efficiency of a toner image from an image bearing member to a transfer receiving member as disclosed in Japanese Patent Application Laid-Open No. Due to the high fluidity, the toner is more easily scattered than when a normal toner is used. In order to prevent toner scattering, for example, Japanese Patent Application Laid-Open No. 2-143265 discloses that a toner having the highest content of a fluidity improving additive to toner is used in a developing device for the first color, and the order of the developing devices is changed. The following method is used to lower the fluidity of the toner image in the uppermost layer by lowering the fluidity of the toner image formed by the transfer to the upper layer by using a toner having a low content of the fluidity improving additive in accordance with the following. It has been disclosed. Further, Japanese Patent Application Laid-Open No. Hei 5-10786
In Japanese Patent Application Laid-Open No. 4 (1999) -197, the toner having the largest average particle size is used for the developing device of the first color, and the toner having the larger average particle size is used according to the order of the developing devices. A method is disclosed in which the fluidity of the toner image in the uppermost layer is reduced by lowering the property toward the upper layer.

However, according to the methods disclosed in these publications, the adhesion between the uppermost toner image which is most difficult to transfer and the photoreceptor layer on the surface of the image carrier increases, and the uppermost toner image is hardly transferred.
The transfer efficiency of the image is reduced. In particular, FIG. 14 and FIG.
In the image forming apparatus using the intermediate transfer member as shown in (1), the transfer efficiency of the uppermost toner image at the time of the secondary transfer is greatly reduced, and the image quality is deteriorated.

In addition to these methods, Japanese Unexamined Patent Publication No.
In Japanese Patent Application Laid-Open No. 54-154, before the transfer of the uppermost toner image, the lower toner image adjacent to the uppermost toner image is interposed in order to increase the adhesion between the toners of the lower toner image adjacent to the uppermost toner image. A method of presumptively depositing on an intermediate using a heating means at the stage of formation on the body is disclosed. However, in this method, there is a problem that power consumption is increased by using a heating unit, and a problem is that the characteristics of the photosensitive layer on the surface of the image carrier are changed due to a rise in temperature.

In view of the above circumstances, an object of the present invention is to provide an image forming apparatus in which the occurrence of toner scattering during multiple transfer of a plurality of color toner images onto a transfer target is prevented.

[0013]

According to a first aspect of the present invention, there is provided an image forming apparatus comprising: one or a plurality of image carriers having a surface on which a toner image is formed; When a plurality of image carriers are present, toner image forming means for sharing toner images of a plurality of colors in total on the plurality of image carriers, and a plurality of toner images formed on the image carriers. Transferring a plurality of color toner images to a predetermined transfer receiving member such that the plurality of color toner images are superimposed in layers, and finally transferring the plurality of color toner images to a predetermined recording medium. Transfer means, and fixing means for fixing the plurality of color toner images transferred to the recording medium to the recording medium at the same time as the transfer to the recording medium or at a timing later than the transfer to the recording medium, The toner image forming means is provided on the transfer-receiving member. The toner image forming the uppermost layer of the toner images of a plurality of colors superimposed in layers is formed by using a toner having a higher degree of sphericity than the lower layer toner image adjacent to the uppermost layer. Features.

Further, according to the second aspect of the present invention, which achieves the above object,
The image forming apparatus includes one or a plurality of image carriers on which a toner image is formed on a surface, and, when a plurality of image carriers are present on the image carrier, on the plurality of image carriers. The toner image forming means for sharing and forming a plurality of color toner images in total, and the plurality of color toner images formed on the image carrier are superimposed in a layered manner. Transfer means for transferring the plurality of color toner images to a predetermined recording medium, and recording the plurality of color toner images transferred to the recording medium. Fixing means for fixing to the recording medium at the same time as the transfer to the medium or at a timing later than the transfer to the recording medium, wherein the toner image forming means comprises Forming the uppermost layer of the toner image The over image, and characterized in that formed using more toners amount of peeling particles than the lower layer of the toner image adjacent to the top layer.

The third object of the present invention to achieve the above object is as follows.
The image forming apparatus includes one or a plurality of image carriers on which a toner image is formed on a surface, and, when a plurality of image carriers are present on the image carrier, on the plurality of image carriers. The toner image forming means for sharing and forming a plurality of color toner images in total, and the plurality of color toner images formed on the image carrier are superimposed in a layered manner. Transfer means for transferring the plurality of color toner images to a predetermined recording medium, and recording the plurality of color toner images transferred to the recording medium. Fixing means for fixing to the recording medium at the same time as the transfer to the medium or at a timing later than the transfer to the recording medium, wherein the toner image forming means comprises Forming the uppermost layer of the toner image The over image, and characterized in that formed using a large toner having an average particle diameter than the lower layer of the toner image adjacent to the top layer.

The fourth object of the present invention to achieve the above object.
The image forming apparatus includes one or a plurality of image carriers on which a toner image is formed on a surface, and, when a plurality of image carriers are present on the image carrier, on the plurality of image carriers. The toner image forming means for sharing and forming a plurality of color toner images in total, and the plurality of color toner images formed on the image carrier are superimposed in a layered manner. Transfer means for transferring the plurality of color toner images to a predetermined recording medium, and recording the plurality of color toner images transferred to the recording medium. Fixing means for fixing to the recording medium at the same time as the transfer to the medium or at a timing later than the transfer to the recording medium, wherein the transfer means sequentially transfers the toner images of the plurality of colors to the object to be transferred. Wherein the image forming apparatus is In the state where all the toner images of the other colors are transferred onto the transfer object, except for one color toner image of a plurality of color toner images superimposed on the transfer object in layers. And a liquid spraying means for spraying a liquid onto the toner image transferred onto the transfer object.

The fifth object of the present invention to achieve the above object is as follows.
The image forming apparatus includes one or a plurality of image carriers on which a toner image is formed on a surface, and, when a plurality of image carriers are present on the image carrier, on the plurality of image carriers. The toner image forming means for sharing and forming a plurality of color toner images in total, and the plurality of color toner images formed on the image carrier are superimposed in a layered manner. Transfer means for transferring the plurality of color toner images to a predetermined recording medium, and recording the plurality of color toner images transferred to the recording medium. Fixing means for fixing to the recording medium at the same time as the transfer to the medium or at a timing later than the transfer to the recording medium, wherein the transfer means sequentially transfers the toner images of the plurality of colors to the object to be transferred. Wherein the image forming apparatus is In the state where all the toner images of the other colors are transferred onto the transfer object, except for one color toner image of a plurality of color toner images superimposed on the transfer object in layers. And a liquid supply means for supplying a liquid to the toner image by bringing a member impregnated with the liquid into contact with the surface of the toner image transferred onto the transfer object.

According to the sixth aspect of the present invention, which achieves the above object,
The image forming apparatus includes one or a plurality of image carriers on which a toner image is formed on a surface, and, when a plurality of image carriers are present on the image carrier, on the plurality of image carriers. The toner image forming means for sharing and forming a plurality of color toner images in total, and the plurality of color toner images formed on the image carrier are superimposed in a layered manner. Transfer means for transferring the plurality of color toner images to a predetermined recording medium, and recording the plurality of color toner images transferred to the recording medium. Fixing means for fixing to the recording medium at the same time as the transfer to the medium or at a timing later than the transfer to the recording medium, wherein the transfer means sequentially transfers the toner images of the plurality of colors to the object to be transferred. Wherein the image forming apparatus is In the state where all the toner images of the other colors are transferred onto the transfer object, except for one color toner image of a plurality of color toner images superimposed on the transfer object in layers. And a pressing means for pressing the surface of the toner image transferred onto the transfer object.

The “recording medium” in each of the first to sixth image forming apparatuses of the present invention may be a “transfer medium” itself.

[0020]

Embodiments of the present invention will be described below. FIG. 1 is a schematic configuration diagram showing a first embodiment of the image forming apparatus of the present invention. This embodiment corresponds to a first image forming apparatus of the present invention. FIG. 1 shows toner images of cyan (C), magenta (M), yellow (Y), and black (K), respectively, which include an image carrier 12, a charger, an LED, a laser scanner, and a developing device. Forming units 11a, 11b, 11c, 11
d, a transfer paper belt 13 on which a toner image formed on the image carrier 12 of each of the image forming units is transferred and which circulates and moves in the direction of arrow A; Paper conveying device 14 for supplying the toner image formed on each image carrier 12 to the recording belt P at each transfer position T1, and transfer rollers 15a, 15b, 15c, 15d, The image forming apparatus 10 includes a transfer power supply 16 for applying a transfer bias voltage to each of the transfer rollers, a peeling static eliminator 17 for peeling the recording paper P from the transfer / conveying belt 13, and a fixing device 18. Have been.

The image forming units 11a, 11b, 11c and 11d in the image forming apparatus 10 correspond to the toner image forming means according to the present invention. And the transfer rollers 15a, 15b, 1 in the image forming apparatus 10.
5c, 15d and the transfer power supply 16 correspond to the transfer means according to the present invention.

In the image forming apparatus 10, first, a black (K) toner image formed on the image carrier 12 of the image forming unit 11d is recorded at the transfer position T1 of the image forming unit 11d by the transfer roller 15d. The yellow (Y) toner image formed on the image carrier 12 of the image forming unit 11c so as to be transferred onto the sheet P and then superimposed on the transferred black (K) toner image Is transferred onto the recording paper P by the transfer roller 15c at the transfer position T1 of the image forming unit 11c. Similarly, the magenta (M) and cyan (C) toner images formed on the image carrier 12 of the image forming units 11b and 11a are sequentially superimposed on the black (K) and yellow (Y) toner images. And a four-color toner image is formed on the recording paper P.

After the transfer by the final-stage image forming unit 11a is completed, the recording paper P is peeled off from the transfer / conveying belt 13 by the peeling static eliminator 17, and the four color toners on the recording paper P by the fixing device 18. The image is fixed to complete the color image. The developing unit for cyan (C) built in the image forming unit 11a of the image forming apparatus 10 uses a spherical toner having a high degree of sphericity, and is built in the other image forming units 11b, 11c, and 11d. An irregular toner is used in the developed developing device.

In the present invention, the degree of sphericity is defined as the toner particle size obtained by taking a photomicrograph of the toner magnified 1000 times using a JEOL SEM (T300) and analyzing the image with an image analyzer. Is the value calculated by the following equation:

[0025]

## EQU1 ## Degree of sphericity = ト ナ ー (4π−Sp) / C × 100 where Sp is the projected area of the toner particles, and C is the circumference of the projected image. Generally, toner particles produced by a melt-kneading-pulverization method or the like have an irregular shape, and the sphericity of the toner particles usually exceeds 150. On the other hand, toner particles produced by an emulsion polymerization method or the like are substantially spherical, and the degree of sphericity of the toner particles is 120 or less. In this embodiment, the image forming units 11b, 11c, and 11d have a sphericity of 1
In the image forming unit 11a, 60 irregular toners and a spherical toner having a sphericity of 110 are used.

The transfer and transport belt 13 is made of a polymer film such as polyimide, polycarbonate, or PVdF, or a conductive film obtained by adding a conductive filler such as carbon black thereto. Transfer roller 15a,
15b, 15c, 15d are silicone rubber, EPDM,
A material made conductive by adding a conductive filler such as carbon black to synthetic rubber such as urethane rubber is used. The diameter of the transfer roller is about 15 to 30 mm.
A transfer bias voltage of about +0.5 to 1.5 kV is applied from the power supply 16 to the transfer rollers 15a, 15b, 15c, and 15d, and the toner images are image-formed by the image forming units 11a, 11b, 11c, and 11c by the transfer bias voltage. 11d
Is sequentially multiplex-transferred to the recording paper P by electrostatic force. Thereafter, the charge of the recording paper P is removed by the peeling static eliminator 17 to weaken the adhesion of the recording paper P to the transfer / transport belt 13 due to static electricity, and the recording paper P is peeled from the transfer / transport belt 13. Finally, the toner image on the recording paper P is fixed by the fixing device 18 to obtain a color image.

When a color image was formed using this image forming apparatus 10 and the image quality was evaluated, an image having good image quality was obtained. For comparison, magenta (M), yellow (Y), and black (K) toners of the image forming units 11b, 11c, and 11d were also subjected to image formation in place of the spherical toner. ) The toner was scattered immediately after the primary transfer, and only a blurred image such as a blurred image was obtained. Conversely, all the image forming units 11a, 11b, 11c,
When an image was formed by replacing the toner 11d with the irregular toner, the transfer efficiency of the cyan (C) toner of the image forming unit 11a was reduced, and only an image having a color balance was lost.

As described above, in this embodiment, the image forming units 11a, 11b, 11c and 11d
The cyan (C) toner image forming the uppermost layer of the four color toner images superimposed in layers is formed using a toner having a higher degree of sphericity than the toner image of the lower layer adjacent to the uppermost layer. By forming the toner image, the adhesive force of the toner image of the uppermost layer is made smaller than the adhesive force of the toner image of the adjacent lower layer, so that toner scattering can be prevented while maintaining high transfer efficiency of the toner image of the uppermost layer.

FIG. 2 is a diagram showing the behavior of the toner image formed on the transfer object. As shown in FIG.
The behavior of each toner layer when the three-layered toner images t1, t2, and t3 formed thereon are transferred so as to be superposed in layers on the transfer target (recording paper P) will be considered. Now
The force that causes the toner image t1 of the uppermost layer that tends to cause toner scattering to remain on the image carrier 12 is FS, and the force that causes the toner image t1 to transfer from the image carrier 12 to the recording paper P is F.
T, when the width of the transfer nip is WT, the toner image t1 is transferred from the image carrier 12 to the recording paper P when FS <FT. The details of FS and FT include electrostatic force, mirror image force, van der Waals force, liquid bridge force, and gravity.

In the case of electrostatic transfer, the transfer of toner can be controlled by controlling the direction and magnitude of the electrostatic force. However, the magnitude of the electrostatic force is limited, and the electrostatic force to be transferred is limited. If the image force, Van der Waals force, liquid bridging force, and the like in the direction in which the toner tends to remain on the image carrier side are larger than the magnitude of the force, the toner transfer is not performed smoothly. In particular, in an image forming apparatus that forms a color image by multi-transferring toners of a plurality of colors, the image transfer by the electrostatic force, mirror image force, van der Waals force, liquid bridging force, etc. of the uppermost toner image transferred last. Since the adhesive force with the body is larger than the electrostatic force toward the transfer target, the transfer efficiency of the toner is reduced.

In order to improve this, there is a method of increasing the degree of spheroidization of the toner or adding a transfer aid to the toner to reduce the adhesive force FS with the image carrier to increase the transfer efficiency. When such processing is applied to all of the plurality of toner layers, the image force between the toner layers, van der Waals force, liquid bridging force, and the like also become small. Therefore, the electrostatic force between the toner particles after passing through the transfer nip WT WT is reduced. The uppermost toner image t1 may be scattered by a repulsive force.

In order to prevent the scattering of the uppermost toner image t1 while ensuring a high transfer efficiency, the lower toner image t2 is maintained while the adhesive force FS of the uppermost toner image t1 to the image carrier 12 is kept small. , T3 must be as large as possible. As a specific method, the uppermost toner image t
For 1, it is effective to use a spherical toner having a high degree of sphericity produced by a polymerization method or the like, and to use an amorphous toner having a low degree of sphericity produced by a pulverization method or the like for the lower toner images t2 and t3. is there.

Next, a second embodiment of the present invention will be described. This embodiment corresponds to a second image forming apparatus of the present invention. In the second embodiment, a method different from that of the first embodiment is employed as a specific method for keeping the adhesion FS of the uppermost toner image t1 to the image carrier 12 small. That is, in the present embodiment, the toner image forming unit converts the toner image forming the uppermost layer of the toner images of a plurality of colors superimposed in layers on the transfer target body into the toner image of the lower layer adjacent to the uppermost layer. The toner is formed by using a toner to which a large amount of releasable fine particles are added. As the releasable fine particles, hydrophobic silica fine particles having a particle diameter of 40 nm are used.

As the image forming apparatus, the same one as the image forming apparatus 10 (see FIG. 1) of the first embodiment is used, and magenta (M) and yellow, which are respectively built in the image forming units 11b, 11c and 11d. (Y) and black (K) developing units using an irregular toner having an area coverage of hydrophobic silica fine particles of 20%, and an image forming unit 1
Only the developing device for cyan (C) built in 1a uses an irregular toner having an area coverage of hydrophobic silica fine particles of 50%.

As described above, the same image formation as in the first embodiment was performed and the image quality was evaluated. As a result, an image having good image quality was obtained. For comparison, similar image formation was performed on all the developing units of the image forming units 11a to 11d using an irregular toner having an area coverage of hydrophobic silica fine particles of 50%, and the image quality was evaluated. The toner image of cyan (C) formed by the above was scattered immediately after being transferred to the recording paper P, and only a blurred image such as blurred image was obtained. Conversely, the image forming units 11a to 11
The same image formation was performed using amorphous toner having an area coverage of hydrophobic silica fine particles of 20% in all of the developing devices of d, and the image quality was evaluated.
The transfer efficiency of the cyan (C) toner image formed in 1a to the recording paper P was insufficient, the color balance was lost, and the image quality deteriorated.

Next, a third embodiment of the present invention will be described. This embodiment corresponds to a third image forming apparatus of the present invention. The third embodiment employs a method different from the first and second embodiments as a specific method for keeping the adhesion FS of the uppermost toner image t1 to the image carrier 12 small. is there. That is, in the present embodiment, the toner image forming unit converts the toner image forming the uppermost layer of the toner images of a plurality of colors superimposed in layers on the transfer target body into the toner image of the lower layer adjacent to the uppermost layer. The toner is formed using a toner having a larger average particle diameter than that of the toner.

As the image forming apparatus, the same one as the image forming apparatus 10 of the first and second embodiments (see FIG. 1) is used, and the magenta (M) built in the image forming units 11b, 11c, 11d respectively. ), Yellow (Y), and black (K) developing devices use spherical toner having an average particle size of 5 μm, and only the cyan (C) developing device built in the image forming unit 11a has an average particle size of 10 μm. Was used.

As described above, image formation was performed in the same manner as in the first and second embodiments, and the image quality was evaluated. As a result, an image having good image quality was obtained. For comparison, similar image formation was performed on all the developing units of the image forming units 11a to 11d using spherical toner having an average particle diameter of 10 μm, and the image quality was evaluated.
The cyan (C) toner image formed by a was scattered immediately after being transferred to the recording paper P, and only an image blurred like an image was obtained. Conversely, similar image formation was performed on all the developing units of the image forming units 11a to 11d using a spherical toner having an average particle diameter of 5 μm, and the image quality was evaluated. The cyan (C) formed by the image forming unit 11a was evaluated. 2) The transfer efficiency of the toner image to the recording paper P was insufficient, and the color balance was lost, and the image quality deteriorated.

Next, a fourth embodiment of the present invention will be described. FIG. 3 is a schematic configuration diagram showing a fourth embodiment of the image forming apparatus of the present invention. This embodiment is the first embodiment of the present invention.
Of the image forming apparatus. The image forming apparatus 20 illustrated in FIG. 3 includes a belt-shaped intermediate transfer body 21 that circulates and moves in the direction of arrow A instead of the transfer and conveyance belt 13 in the image forming apparatus 10 illustrated in FIG.
In the image forming apparatus 10, the toner images on the plurality of image carriers are transferred to the recording paper P on the transfer / conveyance belt 13 at the respective primary transfer positions T1, and a plurality of color toner images are formed on the recording paper P. On the other hand, in the image forming apparatus 20, the toner images on the plurality of image carriers are primary-transferred to the intermediate transfer body 21 at the respective primary transfer positions T1, and the toner images of a plurality of colors are formed on the intermediate transfer body 21. The difference is that they are formed.

The intermediate transfer member 21 and the recording paper P in the present embodiment correspond to the transfer target in the present invention, and the transfer rollers 15a,
15b, 15c, 15d, the transfer power supply 16, the secondary transfer roller 22, and the secondary transfer power supply 22a correspond to a transfer unit according to the present invention. The image forming apparatus 20 shown in FIG. 3 includes a secondary transfer roller 22 instead of the peeling neutralizer 17 in the image forming apparatus 10 shown in FIG.
A power supply 22a for secondary transfer is provided, and the charge removing device 17 in the image forming apparatus 10 electrostatically separates the recording paper P on the transfer / transport belt 13 from the transfer / transport belt 13. In contrast, the image forming apparatus 20
Transfer Roller 22 and Secondary Transfer Power Supply 22
a, the recording paper P is supplied to the secondary transfer position T2 by the recording paper transport device 14 at the timing at which the toner images of a plurality of colors formed on the intermediate transfer body 21 are transported to the secondary transfer position T2. You. Thus, the toner images of a plurality of colors sandwiched between the intermediate transfer body 21 and the recording paper P are collectively transferred onto the recording paper P by the secondary transfer roller 22 disposed at the secondary transfer position T2. Other image forming apparatuses 20
Are the same as those of the image forming apparatus 10 shown in FIG.

The image forming apparatus 20 differs from the image forming apparatus 10 shown in FIG. 1 in the transfer object, but superimposes a plurality of color toner images formed by a plurality of image forming units on the transfer object. Is exactly the same. In the image forming apparatus 20, the multi-color toner images formed on the transfer target (intermediate transfer member 21) in the transfer step described above are transferred to the recording paper P by the secondary transfer roller 22 at the secondary transfer position T2 as described above. The batch is transferred to the top. The plurality of color toner images on the recording paper P are fixed by the fixing device 18 to complete a color image.

As the intermediate transfer member 21, a polymer film made of polyimide, polycarbonate, PVdF or the like, or a material made conductive by adding a conductive filler such as carbon black to synthetic rubber such as silicon rubber or fluorine rubber is used. . The secondary transfer roller 22 is a transfer roller 15a, 1
Materials similar to 5b, 15c, and 15d can be used. The secondary transfer roller 22 has a secondary transfer power source 22.
A voltage of about +1.5 to 3.0 kV is applied from a, and a plurality of color toner images formed on the intermediate transfer body 21 are collectively transferred to the recording paper P by the electrostatic force.

In this embodiment, the image carrier 12 of the uppermost toner image t1 is determined based on the behavior of the uppermost toner image among the toner images of a plurality of colors formed on the transfer target, as described with reference to FIG. As a specific method for keeping the adhesive force FS with the toner image forming unit small, as in the first embodiment, the toner image forming unit includes:
The toner image forming the uppermost layer of the toner images of a plurality of colors superimposed in layers on the transfer medium is formed using a toner having a higher degree of sphericity than the toner image of the lower layer adjacent to the uppermost layer. The method is adopted. That is, spherical toner is used for the developing units for cyan (C) and black (K) built in the image forming units 11a and 11d of the image forming apparatus 20, and the image forming units 11b and 11c are used.
The developing device incorporated in the printer uses an irregular toner.

Here, the reason that the spherical toner is also used for the image forming unit 11d is that the cyan (C) toner image by the image forming unit 11a is the uppermost layer in the primary transfer, but is the image in the secondary transfer. Forming unit 11
This is because the black (K) toner image by d becomes the uppermost layer. After performing the image formation in the same manner as in the first embodiment and evaluating the image quality, an image having a good image quality was obtained. For comparison, a similar image was formed using the spherical toner in the developing units of the image forming units 11b and 11c, and the image quality was evaluated. The cyan (C) toner image formed by the image forming unit 11a was primarily transferred. Immediately after the image was scattered, only a blurred image, such as a blurred image, was obtained. Also, conversely,
When the same image was formed on all the developing units of the image forming units 11a to 11d using the irregular toner and the image quality was evaluated, the transfer efficiency was insufficient as a whole. The transfer efficiency of the toner image and the black (K) toner image of the image forming unit 11d was low, the color balance was lost, and the image quality was deteriorated. Further, if only the cyan (C) toner of the image forming unit 11a is changed to the spherical toner, the transfer efficiency of the black (K) toner image in the secondary transfer is reduced.
If only the black (K) toner image of d was used as the spherical toner, the cyan (C) toner image in the primary transfer was blurred and the image quality was deteriorated.

Next, a fifth embodiment of the present invention will be described. FIG. 4 is a schematic configuration diagram showing a fifth embodiment of the image forming apparatus of the present invention. This embodiment is a fourth embodiment of the present invention.
Of the image forming apparatus. The image forming apparatus 30 shown in FIG. 4 has a configuration in which a liquid spraying device 31 is added to the image forming apparatus 20 shown in FIG. Since the image forming apparatus 30 has the same configuration as the image forming apparatus 20 except that the liquid spraying apparatus 31 is added, only the liquid spraying apparatus 31 will be described below.

The liquid spraying device 31 in this embodiment is
This corresponds to the liquid spraying means according to the present invention. In this embodiment,
Based on the behavior of the uppermost toner image of the plurality of color toner images formed on the transfer target described with reference to FIG. 2, the adhesion FS of the uppermost toner image t1 to the image carrier 12 is kept small. As a specific method, the toner image forming the uppermost layer of the toner images of a plurality of colors superimposed in layers on the transfer medium, that is, the other three toner images except the cyan (C) toner image are left.
In a state where all the color toner images are transferred onto the transfer target, a method of spraying a liquid onto the surface of the three-color toner image transferred onto the transfer target is adopted. That is, the liquid spraying device 31 is configured such that the image forming units 11 b to 11 d use the multi-color toner images superimposed on the intermediate transfer body 21 in a layer on the intermediate transfer body 21 which is one of the objects to be transferred.
The remaining 3 (cyan (C) toner image forming the uppermost layer)
The liquid is sprayed from above all the color toner images transferred onto the intermediate transfer body 21.

In the present embodiment, a liquid spraying device 31 is used which has a vibrator such as a piezoelectric element and introduces a liquid such as water into the vibrating surface to form a mist and spray from a nozzle.
FIG. 5 is a schematic configuration diagram of a liquid spray device used in the fifth embodiment of the present invention. As shown in FIG. 5, water 34 is provided on a vibrating surface of a vibrating body 32 having a vibrator such as a piezoelectric element 33.
Is introduced to mist the water 34, and is sprayed from the nozzle 35 onto the toner image T on the intermediate transfer body 21. The liquid to be sprayed is not limited to water, and for example, alcohols such as ethyl alcohol can be used.

For the image forming units 11a to 11d, spherical toner having an average particle diameter of 10 μm, which is relatively easy to cause toner scattering, is used. However, a liquid spray disposed between the image forming unit 11b and the image forming unit 11a is used. Using the device 31, a proper amount of water is sprayed on the black (K), yellow (Y), and magenta (M) laminated toner images before the cyan (C) toner image is transferred, and thereafter, the cyan (C) By transferring the toner image of (1), a good image without toner scattering can be obtained.

After performing the image formation and evaluating the image quality in the same manner as in the first embodiment, an image having good image quality was obtained. For comparison, when the spraying of water by the liquid spraying device 31 was stopped and the same image formation was performed to evaluate the image quality, the image forming unit 11 was evaluated.
The cyan (C) toner image formed by (a) was scattered immediately after the primary transfer, and only a blurred image, such as a blurred image, was obtained.

Next, a sixth embodiment of the present invention will be described. FIG. 6 is a schematic configuration diagram showing a sixth embodiment of the image forming apparatus of the present invention. This embodiment is the fifth embodiment of the present invention.
Of the image forming apparatus. The image forming apparatus 40 shown in FIG. 6 has a configuration in which a liquid application roller 41 is added to the image forming apparatus 20 shown in FIG. Since the image forming apparatus 40 has the same configuration as the image forming apparatus 20 except that the liquid applying roller 41 is added, only the liquid applying roller 41 will be described below.

Liquid application roller 41 in the present embodiment
Corresponds to the liquid supply means according to the present invention. The liquid supply means is not limited to such a roller type, but may be of any type as long as it can smoothly supply an appropriate amount of liquid to the surface of the toner image. In the present embodiment, based on the behavior of the uppermost layer toner image of the plurality of color toner images formed on the transfer target described with reference to FIG. 2, the uppermost layer toner image t1 is attached to the image carrier 12. As a specific method for keeping the adhesion FS small, a cyan (C) toner image that forms the uppermost layer of the four color toner images superimposed in layers on the transfer target is left on the transfer target. A method of supplying a liquid to a toner image by bringing a member impregnated with a liquid into contact with the surface of each of the three color toner images in a state where all the other three color toner images have been transferred onto the transfer-receiving body. Is adopted. That is, the liquid application roller 4
Reference numeral 1 denotes a remaining toner image of one color of cyan (C) among the four color toner images superimposed on the intermediate transfer member 21 in layers by the image forming units 11b to 11d. In a state where all the color toner images are transferred onto the intermediate transfer body 21, the surface of the toner image transferred onto the intermediate transfer body 21 is brought into contact with a roller impregnated with the liquid, so that the liquid Supply water 42. The liquid is not limited to water, and for example, alcohols such as ethyl alcohol can be used.

FIG. 7 is a schematic structural view of a liquid application roller used in the sixth embodiment of the present invention. As shown in FIG. 7, the liquid application roller 41 applies an appropriate amount of water 42 to the surface of the toner image T formed on the intermediate transfer body 21.
As the liquid application roller 41, for example, a roller formed of a water-absorbing polymer such as polyvinyl alcohol or polyvinyl formal, which is impregnated with a liquid such as water in advance is used. The liquid application roller 41 is arranged between the image forming units 11b and 11b, and is brought into contact with the intermediate transfer body 21 while being slightly pressed.

For the image forming units 11a to 11d, spherical toner having an average particle diameter of 10 μm, which is relatively easy to cause toner scattering, is used. However, a liquid coating device disposed between the image forming unit 11b and the image forming unit 11a is used. Roller 41
, An appropriate amount of water is applied to the black (K), yellow (Y), and magenta (M) laminated toner images before the cyan (C) toner image is transferred. By transferring the toner image, an image having good image quality without toner scattering could be obtained. For comparison, water application by the liquid application roller 41 was stopped and the same image formation was performed to evaluate the image quality.
The cyan (C) toner image formed by (a) was scattered immediately after the primary transfer, and only a blurred image, such as a blurred image, was obtained.

Next, a seventh embodiment of the present invention will be described. FIG. 8 is a schematic configuration diagram showing a seventh embodiment of the image forming apparatus of the present invention. This embodiment is the sixth embodiment of the present invention.
Of the image forming apparatus. The image forming apparatus 50 shown in FIG. 8 has a configuration in which a pressing roller 51 is added to the image forming apparatus 20 shown in FIG. The image forming apparatus 30 has the same configuration as the image forming apparatus 20 except that the pressing roller 51 is added.
Only 1 will be described.

The pressing roller 51 in this embodiment corresponds to the pressing means according to the present invention. In the present embodiment, based on the behavior of the uppermost layer toner image of the plurality of color toner images formed on the transfer target described with reference to FIG. 2, the uppermost layer toner image t1 is attached to the image carrier 12. As a specific method for keeping the adhesion FS small, one of a plurality of color toner images superposed in layers on a transfer target body, that is, a cyan (C) toner image and the other three colors are left. In a state where all the toner images are transferred onto the transfer object, a method of pressing the surface of the toner image transferred onto the transfer object is adopted. In other words, the pressing roller 51 is formed by the image forming units 11b to 11d onto the intermediate transfer member 21, which is one of the transfer-receiving members, of the multi-color toner images superimposed on the intermediate transfer member 21 in layers. Except for the cyan (C) toner image forming the upper layer, all of the other three color toner images are
In the state where the toner image is transferred onto the intermediate transfer member 21, the surface of the toner image transferred onto the intermediate transfer body 21 is pressed.

FIG. 9 is a schematic structural view of a pressing roller used in the seventh embodiment of the present invention. As shown in FIG. 9, the pressing roller 51 is formed by forming an elastic layer 53 made of urethane rubber, silicon rubber, EPDM rubber, or the like concentrically around a metal shaft 52. In addition to such a configuration, for example, PTFE
For example, a roller coated with a toner release layer made of a fluororesin such as urea or a binder resin such as urethane or acryl added with fluororesin particles such as PTFE may be used. Such a pressing roller is arranged between the image forming units 11b and 11a and is brought into contact with the intermediate transfer body 21 while being lightly pressed.

For the image forming units 11a to 11d, a spherical toner having an average particle diameter of 10 μm, which is relatively easy to cause toner scattering, is used. A pressing roller disposed between the image forming unit 11b and the image forming unit 11a is used. 51, the surface of the black (K), yellow (Y), and magenta (M) laminated toner images before the transfer of the cyan (C) toner image is lightly pressed. By transferring the toner image, a good image without toner scattering can be obtained. By lightly applying pressure to the toner image surface before the uppermost (cyan (C)) toner image is transferred, the surface unevenness is reduced to the extent that the image is not damaged, and the uppermost (cyan (C)) toner And the contact area between the toners, such as Van der Waals force and liquid crosslinking force, increases. Further, the height of the toner layer is reduced to such an extent that the image is not broken, and the electrostatic transfer force is increased. It is considered that as a result, toner scattering hardly occurs.

Next, an eighth embodiment of the present invention will be described. FIG. 10 is a schematic configuration diagram showing an eighth embodiment of the image forming apparatus of the present invention. The present embodiment corresponds to a first image forming apparatus of the present invention, and is an image forming apparatus of a type in which a toner image is tertiarily transferred using an intermediate transfer drum having two stages. The image forming apparatus 60 shown in FIG. 10 includes the same image forming units 11a, 11b, 11c, and 11d as in the first to seventh embodiments, and the primary transfer position T.
1, the intermediate transfer drums 61 and 62 that rotate in the direction of arrow A in contact with the image forming units 11a and 11b and the image forming units 11c and 11d, respectively, and the intermediate transfer drums 61 and 62 in the secondary transfer position T2. The intermediate transfer drum 63 rotating in the direction of the arrow B, transfer power supplies 61a, 62a, 63a for supplying a predetermined voltage to the intermediate transfer drums 61, 62, 63, respectively, and the intermediate transfer drum 63 and the recording paper at the tertiary transfer position T3. A tertiary transfer roller 64 that contacts through the P; a recording paper transport device 14 that supplies the recording paper P to the tertiary transfer position T3;
8 are provided.

In the present embodiment, the intermediate transfer drum 61,
62, 63 and the recording paper P correspond to the transfer object in the present invention, and the transfer power supplies 61a, 62a, 63a and the tertiary transfer roller 64 in the present embodiment.
Corresponds to the transfer means according to the present invention. The intermediate transfer drums 61, 62, and 63 have, for example, an elastic layer formed by adding a conductive filler such as carbon black or metal oxide to urethane rubber, silicon rubber, EPDM rubber, or the like around a metal shaft. A surface layer is formed on the surface by adding a fluororesin such as PTFE or a binder resin such as urethane or acrylic to a fluororesin particle such as PTFE, and a conductive filler is further added thereon. One having a toner release layer formed thereon is used.

Transfer power supplies 61a, 62a, 63a are connected to the intermediate transfer drums 61, 62, 63, respectively. The transfer power supplies 61a, 62a apply a voltage of +1 kV to the intermediate transfer drums 61, 62, respectively. . Further, the transfer power supply 63 a applies a voltage of about +2 kV to the intermediate transfer drum 63. With this configuration, the cyan (C) and magenta (M) toner images formed by the image forming units 11a and 11b are superimposed on the intermediate transfer drum 61 at the respective primary transfer positions T1. Similarly, the yellow (Y) and black (K) toner images formed by the image forming units 11c and 11d are sequentially primary-transferred so as to be superimposed on the intermediate transfer drum 62. You.

Next, the yellow (Y) and black (K) toner images primarily transferred onto the intermediate transfer drum 61 are secondarily transferred to the intermediate transfer drum 63 at the secondary transfer position T2, and then the intermediate transfer is performed. The cyan (C) and magenta (M) toner images primarily transferred onto the drum 61 are placed on the black (K) and yellow (Y) toner images on the intermediate transfer drum 63 at the secondary transfer position T2. The secondary transfer is performed so as to be superimposed.

Next, the black (K), yellow (Y), magenta (M), and cyan (C) toner images formed on the intermediate transfer drum 63 are transferred to the tertiary transfer position T3.
After being collectively transferred (tertiary transfer) to the recording paper P conveyed to the tertiary transfer position T3 by the tertiary transfer roller 64,
The color image is fixed by the fixing device 18. The reason why a plurality of intermediate transfer drums are used can be explained as follows. Since the intermediate transfer drum does not have elongation or walk unlike a belt, it is easier to obtain color overlay accuracy than a belt. However, when only one intermediate transfer drum is used, as shown in FIG.
The image forming units 6a, 6b, 6c and 6d are arranged radially, and there is a problem that the developing device and other parts cannot be shared. The main reason is that a plurality of image forming units are arranged in parallel by using a plurality of intermediate transfer drums, and a developing device and other parts are shared while ensuring the accuracy of color superposition.

The operation of the image forming apparatus 60 of this embodiment using a plurality of intermediate transfer drums will be described below. FIG. 11 is an enlarged view of a main part of the image forming apparatus shown in FIG. As shown in FIG. 11, a portion corresponding to the intermediate transfer drum 61 among the two secondary transfer positions T2 surrounded by broken lines is a partially enlarged view Z1, and the intermediate transfer drum 6
2 is shown in the figure as a partially enlarged view Z2, and a part of the tertiary transfer position T3 surrounded by a broken line is shown as a partially enlarged view Z3 in the figure.

As shown in the partially enlarged view Z2, the upper toner image of the two-layer toner image secondary-transferred onto the intermediate transfer drum 63 at the secondary transfer position T2 of the intermediate transfer drum 62 is used for image formation. The yellow (Y) toner image provided from the unit 11c, and the lower toner image is a black (K) toner image provided from the image forming unit 11d. Since the pile height (stacking height) of the toner image formed here is limited to two colors at the maximum, scattering of toner and transfer efficiency do not cause a great problem. What is problematic is the transfer position shown as partial enlarged views Z1 and Z3 where the toner pile height is equivalent to four colors at the maximum.

As shown in the partially enlarged view Z1, the upper toner image of the two-layer toner image secondary-transferred onto the intermediate transfer drum 63 at the secondary transfer position T2 of the intermediate transfer drum 61 is used for image formation. The toner image of cyan (C) provided from the unit 11a, and the lower toner image is a toner image of magenta (M) provided from the image forming unit 11b. At this secondary transfer position T2, a maximum of two layers of toner images from the intermediate transfer drum 61 are superimposed on a maximum of two layers of toner images already transferred from the intermediate transfer drum 62 onto the intermediate transfer drum 63. Since the image is transferred, the pile height is a maximum of four colors.

As shown in the partial enlarged view Z3, the intermediate transfer drum 6 is moved at the tertiary transfer position T3 of the intermediate transfer drum 63.
The pile height of the toner image tertiary-transferred from No. 3 onto the recording paper P is also a maximum of four colors. Of the toner images of the maximum four layers, the uppermost toner image is a black (K) toner image provided from the image forming unit 11d, and the lowermost toner image is cyan provided from the image forming unit 11a. 5C is a toner image of FIG.

In the present embodiment, the toner image of the uppermost layer among the toner images having a maximum of four layers, that is, the black (K) toner image provided from the image forming unit 11d and the image forming unit The toner used in the image forming units 11a and 11d for the cyan (C) toner image obtained from the toner 11a is a spherical toner having a small toner-to-toner adhesive force, and yellow (Y) and magenta which are not the uppermost layer are used. As the toner used in the image forming units 11b and 11c for the toner image (M), an irregular toner having a relatively high adhesion between toners is used.

When an image was formed by the image forming apparatus 60 constructed as described above and the image quality was evaluated, it was possible to obtain an image having high transfer efficiency and good image quality without toner scattering. For comparison, when water spraying by the liquid spraying device 31 was stopped and the same image formation was performed to evaluate the image quality, immediately after the cyan (C) toner image formed by the image forming unit 11a was primarily transferred, The image was scattered, and only a blurred image was obtained.

For comparison, the image forming units 11a to 11a
When all the toners used for 1d are spherical toners,
Although the transfer efficiency was high, toner scattering occurred. Further, when all the toners used in the image forming units 11a to 11d were irregular toners, the transfer efficiency of the uppermost layer toner (black (K)) at the time of the tertiary transfer was low, the color tone was changed, and the image quality was deteriorated.

The present embodiment is an example in which the method adopted in the first embodiment is applied to a multiple intermediate transfer member system, but can be similarly applied to the second to seventh embodiments. .

[0071]

As described above, according to the image forming apparatus of the present invention, in a color image forming apparatus such as a color copying machine or a color printer, a plurality of color toner images are sequentially transferred from the image forming unit to the transfer object. In a color image forming apparatus that forms a color image by transferring and transferring in a superimposed state, when a toner image of a plurality of colors is multiplex-transferred onto a transfer target by means described in the above various embodiments. An image forming apparatus in which toner scattering is prevented can be realized.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram illustrating a first embodiment of an image forming apparatus of the present invention.

FIG. 2 is a diagram illustrating the behavior of a toner image formed on a transfer target.

FIG. 3 is a schematic configuration diagram showing a fourth embodiment of the image forming apparatus of the present invention.

FIG. 4 is a schematic configuration diagram illustrating a fifth embodiment of the image forming apparatus of the present invention.

FIG. 5 is a schematic configuration diagram of a liquid spray device used in a fifth embodiment of the present invention.

FIG. 6 is a schematic configuration diagram illustrating a sixth embodiment of the image forming apparatus of the present invention.

FIG. 7 is a schematic configuration diagram of a liquid application roller used in a sixth embodiment of the present invention.

FIG. 8 is a schematic configuration diagram showing a seventh embodiment of the image forming apparatus of the present invention.

FIG. 9 is a schematic configuration diagram of a pressing roller used in a seventh embodiment of the present invention.

FIG. 10 is a schematic configuration diagram illustrating an eighth embodiment of the image forming apparatus of the present invention.

11 is an enlarged view of a main part of the image forming apparatus shown in FIG.

FIG. 12 is a schematic configuration diagram illustrating an example of a conventional color image forming apparatus.

FIG. 13 is a schematic configuration diagram illustrating another example of a conventional color image forming apparatus.

FIG. 14 is a schematic configuration diagram illustrating another example of a conventional color image forming apparatus.

FIG. 15 is a schematic configuration diagram illustrating another example of a conventional color image forming apparatus.

FIG. 16 is a diagram illustrating a toner scattering phenomenon when a toner image on an image carrier is transferred to a transfer target.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Image forming unit 1a Electrostatic latent image forming device 1b Image carrier 1c Rotary developing machine 2 Transfer / conveying roll 2 'Transfer / conveying belt 3 Transfer receiving member 4 Paper peeling device 5 Fixing device 6a, 6b, 6c, 6d Image Forming unit 7 Intermediate transfer drum 8 Secondary transfer device 9 Intermediate transfer belt 10, 20, 30, 40, 50, 60 Image forming apparatus 11a, 11b, 11c, 11d Image forming unit 12 Image carrier 13 Transfer belt 14 Recording Paper transport device 15a, 15b, 15c, 15d Transfer roller 16 Transfer power supply 17 Peeling charge remover 18 Fixing device 21 Intermediate transfer body 22 Secondary transfer roller 22a Secondary transfer power supply 31 Liquid spray device 32 Vibrating body 33 Piezoelectric element 34 Water 35 nozzle 41 liquid application roller 42 water 51 pressing roller 52 metal shaft 53 elastic layer 6 1, 62, 63 Intermediate transfer drum 61a, 62a, 63a Transfer power supply 64 Tertiary transfer roller

Claims (7)

[Claims] 1. An image carrier having a surface on which a toner image is formed, and a plurality of image carriers, when there are a plurality of image carriers on the image carrier, shared by the plurality of image carriers. A toner image forming means for forming a plurality of color toner images in total; and a plurality of color toner images formed on the image carrier, wherein the plurality of color toner images are superimposed in layers. Transfer means for finally transferring the plurality of color toner images to a predetermined recording medium, and transferring the plurality of color toner images transferred to the recording medium to the predetermined recording medium. Fixing means for fixing to the recording medium at the same time as the transfer to the medium or at a timing later than the transfer to the recording medium, wherein the toner image forming means is superposed in a layer on the transfer object Form the top layer of the multicolor toner image A toner image, an image forming apparatus, characterized in that formed using a toner having a high sphericity than the lower layer of the toner image adjacent to the top layer. 2. An image carrier having a toner image formed on a surface thereof, and a plurality of image carriers provided on the image carrier when the plurality of image carriers are present on the image carrier. A toner image forming means for forming a plurality of color toner images in total; and a plurality of color toner images formed on the image carrier, wherein the plurality of color toner images are superimposed in layers. Transfer means for finally transferring the plurality of color toner images to a predetermined recording medium, and transferring the plurality of color toner images transferred to the recording medium to the predetermined recording medium. Fixing means for fixing to the recording medium at the same time as the transfer to the medium or at a timing later than the transfer to the recording medium, wherein the toner image forming means is superposed in a layer on the transfer object Form the top layer of the multicolor toner image A toner image, an image forming apparatus, characterized in that also the lower layer of the toner image adjacent to the top layer and forms with more toners amount of release fine particles. 3. An image carrier having a surface on which a toner image is formed, and a plurality of image carriers on the image carrier when the plurality of image carriers are present on the image carrier. A toner image forming means for forming a plurality of color toner images in total; and a plurality of color toner images formed on the image carrier, wherein the plurality of color toner images are superimposed in layers. Transfer means for finally transferring the plurality of color toner images to a predetermined recording medium, and transferring the plurality of color toner images transferred to the recording medium to the predetermined recording medium. Fixing means for fixing to the recording medium at the same time as the transfer to the medium or at a timing later than the transfer to the recording medium, wherein the toner image forming means is superposed in a layer on the transfer object Form the top layer of the multicolor toner image A toner image, an image forming apparatus, characterized in that formed using a large toner of the lower average particle size than the toner image adjacent to the top layer. 4. An image carrier having a surface on which a toner image is formed, and a plurality of image carriers provided on the image carrier when the plurality of image carriers are present on the image carrier. A toner image forming means for forming a plurality of color toner images in total; and a plurality of color toner images formed on the image carrier, wherein the plurality of color toner images are superimposed in layers. Transfer means for finally transferring the plurality of color toner images to a predetermined recording medium, and transferring the plurality of color toner images transferred to the recording medium to the predetermined recording medium. Fixing means for fixing to the recording medium at the same time as the transfer to the medium or at a timing later than the transfer to the recording medium, wherein the transfer means sequentially transfers the plurality of color toner images to the transfer object. The image forming apparatus. And transferring all the toner images of the other colors except the one color toner image among the plurality of color toner images superimposed on the transferred object in a layered manner on the transferred object. An image forming apparatus comprising: a liquid spraying unit that sprays a liquid onto the toner image transferred onto the transfer target in a state where the toner image is transferred. 5. One or a plurality of image carriers on which a toner image is formed on a surface, and when a plurality of image carriers are present on the image carrier, the plurality of image carriers are shared on the plurality of image carriers. A toner image forming means for forming a plurality of color toner images in total; and a plurality of color toner images formed on the image carrier, wherein the plurality of color toner images are superimposed in layers. Transfer means for finally transferring the plurality of color toner images to a predetermined recording medium, and transferring the plurality of color toner images transferred to the recording medium to the predetermined recording medium. Fixing means for fixing to the recording medium at the same time as the transfer to the medium or at a timing later than the transfer to the recording medium, wherein the transfer means sequentially transfers the plurality of color toner images to the transfer object. The image forming apparatus. And transferring all the toner images of the other colors except the one color toner image among the plurality of color toner images superimposed on the transferred object in a layered manner on the transferred object. Image forming apparatus comprising: a liquid supply unit that supplies a liquid to a toner image by bringing a member impregnated with a liquid into contact with a surface of the toner image transferred onto the transfer target in a state where the toner image is transferred onto the transfer object. apparatus. 6. The image forming apparatus according to claim 4, wherein the liquid is water. 7. One or a plurality of image carriers on which a toner image is formed on the surface, and, when a plurality of image carriers are present on the image carrier, sharing on the plurality of image carriers. A toner image forming means for forming a plurality of color toner images in total; and a plurality of color toner images formed on the image carrier, wherein the plurality of color toner images are superimposed in layers. Transfer means for finally transferring the plurality of color toner images to a predetermined recording medium, and transferring the plurality of color toner images transferred to the recording medium to the predetermined recording medium. Fixing means for fixing to the recording medium at the same time as the transfer to the medium or at a timing later than the transfer to the recording medium, wherein the transfer means sequentially transfers the plurality of color toner images to the transfer object. The image forming apparatus. And transferring all the toner images of the other colors except the one color toner image among the plurality of color toner images superimposed on the transferred object in a layered manner on the transferred object. An image forming apparatus comprising: a pressing unit that presses a surface of the toner image transferred onto the transfer target in the closed state.