JPH11249459A - Image forming device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain an image without a void part in an image forming device using an intermediate transfer body. SOLUTION: After the image formed on a first image carrier 1 is transferred to the intermediate transfer body 20, the image is further transferred to a second image carrier 24. Since the surface moving speed of the intermediate transfer body 20 is made different from that of the image carrier 1 and also the surface moving speed of the body 20 is made different from that of the body 24, so that shearing force for wiping the image from the surface of the carrier 1 to an intermediate body 20 side or from the body 20 side to a second image carrier 24 side exerts by the speed difference, the transfer efficiency is improved and the image is transferred without a void part.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a transfer type image forming apparatus. More specifically, a transferable image (visible image) of target image information is formed and supported on a first image carrier by an image forming process, and after the transferable image is once transferred onto an intermediate transfer body, The present invention relates to an image forming apparatus, such as a copying machine, a printer, and a facsimile, which further transfers an image on a second image carrier to output an image formed product.

In the above, the first image carrier is, for example, an electrophotographic photosensitive member, an electrostatic recording dielectric, a magnetic recording magnetic material, or the like.

An image forming process is, for example, an electrophotographic process.
Such processes include an electrostatic recording process and a magnetic recording process.

The second image carrier is, for example, a paper sheet such as a transfer material, a recording paper, or a printing paper.

[0005]

2. Description of the Related Art FIG. 7 schematically shows an example of an image forming apparatus using an intermediate transfer member. The image forming apparatus of the present embodiment is a color image forming apparatus (copier or laser beam printer) using an electrophotographic process.

[0006] Reference numeral 1 denotes a rotating drum type electrophotographic photosensitive member (hereinafter, referred to as a first image bearing member)
And is driven to rotate at a predetermined peripheral speed (process speed) in the clockwise direction indicated by the arrow.

The photosensitive drum 1 is uniformly charged to a predetermined polarity and potential by a primary charger (corona discharger) 2 in the course of rotation, and then is exposed to image exposure means (not shown). The image exposure 3 by a scanning exposure system using a laser scanner that outputs a laser beam modulated in accordance with a time-series electric digital pixel signal of image information. (For example, a magenta component image) is formed.

Next, the electrostatic latent image is formed by a first developing device 41 (magenta developing device) into a magenta toner M of a first color.
(Colored charged particles). At this time, the second to fourth developing devices 42, 43 and 44 (each developing device for cyan, yellow and black) are turned off and do not act on the photosensitive drum 1, and the magenta toner of the first color is used. The image is not affected by the second to fourth developing units 42 to 44.

Reference numeral 5 denotes an endless intermediate transfer belt as an intermediate transfer member, which is suspended between three conductive rollers 6, 71, 72 of a conductive roller 6, and two turn rollers 71, 72. The conductive roller 6 holds the belt 5 in pressure contact with the photosensitive drum 1 with a predetermined pressing force, and a transfer nip portion N as a transfer portion is formed between the photosensitive drum 1 and the intermediate transfer belt 5. Have been.

The intermediate transfer belt 5 is driven to rotate at the same peripheral speed as the photosensitive drum 1 in the counterclockwise direction indicated by the arrow.
A transfer bias having a polarity (plus) opposite to the toner charge polarity (minus in this example) of the toner image formed on the photosensitive drum 1 is applied to the conductive roller 6 from a first bias power supply 61. The intermediate transfer belt 5 is a dielectric film such as polyester or polyethylene, a composite layer type dielectric film having a back surface lined with a conductor, or the like.

The electric field formed in the transfer nip area by the transfer bias applied to the conductive roller 6 while the magenta toner image of the first color formed and carried on the surface of the photosensitive drum 1 passes through the transfer nip portion N. Thus, the intermediate transfer is sequentially performed on the outer surface of the rotating intermediate transfer belt 5.

After the transfer of the first color magenta toner image onto the intermediate transfer belt 5, the surface of the photosensitive drum 1 is cleaned by the cleaning device 14.

Hereinafter, similarly,. Charge on the rotating photosensitive drum 1 → image exposure 3 corresponding to a second color component image (for example, a cyan component image) → development with cyan toner C of a second developing device 42 (cyan developing device) → second formed color Transfer of a certain cyan toner image to the intermediate transfer belt 5 → cleaning of the surface of the photosensitive drum 1 by the cleaning device 14, Charge on the rotating photosensitive drum 1 → image exposure corresponding to a third color component image (eg, yellow component image) 3 → third
Developing with the yellow toner Y of the developing device 43 (yellow developing device) → transfer of the formed yellow toner image of the third color to the intermediate transfer belt 5 → cleaning of the photosensitive drum 1 surface by the cleaning device 14; Charge on the rotating photosensitive drum 1 → Image exposure 3 corresponding to a fourth color component image (for example, a black (black) component image)
→ Development of the fourth developing device 44 (black developing device) with the black toner B → Transfer of the formed black toner image of the fourth color to the intermediate transfer belt 5 → Cleaning of the photosensitive drum 1 surface by the cleaning device 14. The four image formation / transfer cycles are sequentially executed, so that the four toner images (magenta, cyan, yellow, and black toner images) are sequentially superimposed on the outer surface of the rotary intermediate transfer belt 5. The transferred color toner image (mirror image) corresponding to the target color image is formed.

Next, the paper feed roller 1
0 indicates a transfer material (sheet) as a second image carrier
The sheet 24 is separated and conveyed one by one, and is fed to the transfer nip N at a predetermined timing through the register roller pair 11 and the transfer guide 12.

Further, the bias power supply for the conductive roller 6 is switched from the first power supply 61 to the second bias power supply 62, so that the bias of the same polarity (-) as the toner of the transfer composite color toner image on the intermediate transfer belt 5 becomes conductive. The transfer composite color toner image on the intermediate transfer belt 5 is sequentially transferred to the surface of the transfer material 24 fed to the transfer nip N by being applied to the roller 6.

The intermediate transfer belt 5 passes through the transfer nip N
The transfer material 24 to which the above toner image has been transferred is introduced into the fixing device 15 via the transport guide 13 and is heated and pressed by the fixing roller 16 and the pressure roller 17 which have been heated and regulated at a predetermined temperature, so that the toner image is transferred. , And is output as a color image formed product.

Reference numeral 8 denotes a cleaning device for the intermediate transfer belt 5, which is normally kept in a non-operating state with respect to the belt 5, but is transferred to the outer surface of the belt 5 when the transfer of the toner image to the transfer material 24 is completed. On the other hand, the outer surface of the belt 5 is cleaned by the operation of the cleaning device 8.

[0018]

However, when the toner image on the photosensitive drum 1 is transferred to the belt 5 which is a conventional intermediate transfer member, the toner image transferred on the belt 5 as shown in FIG. A so-called “hollow portion” a easily occurs on T. This is because the surface of the photosensitive drum 1 has an adhesive force with respect to the toner.

On the other hand, the same can be said when a toner image is transferred from the intermediate transfer belt 5 side to the transfer material 24 side through the sequential superimposition transfer process of all the toner images of the first to fourth colors. Contrary to this, as the toner adhesion of the belt 5 is poor, the hollow tends to be less likely to occur.

Therefore, in an image forming apparatus using such an intermediate transfer member 5, there is no intermediate transfer member having a surface layer appropriate for toner adhesion, and an image without a hollow portion a is formed on the transfer material 24. It was difficult to form.

Accordingly, an object of the present invention is to provide an image forming apparatus of the type using an intermediate transfer member, which can obtain an image without the hollow portion a as described above.

[0022]

SUMMARY OF THE INVENTION The present invention is an image forming apparatus having the following configuration.

(1) In an image forming apparatus, an image formed on a first image carrier is transferred onto an intermediate transfer member, and further transferred onto a second image carrier. An image forming apparatus, wherein the moving speed is different from the surface moving speed of the first image carrier.

(2) The surface moving speed of the intermediate transfer member is different from the surface moving speed of the second image carrier.
An image forming apparatus according to claim 1.

<Operation> The surface moving speed of the intermediate transfer member is set to the first
By making the surface movement speed of the intermediate transfer member different from the surface movement speed of the second image carrier, the intermediate transfer from the first image carrier surface by the speed difference. By applying a shearing force such as wiping an image to the body side or from the intermediate transfer body side to the second image carrier side, transfer efficiency is improved and image transfer without "hollow-out" can be performed.

[0026]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS <First Embodiment> (FIGS. 1 and 2) FIG. 1 shows an image forming apparatus shown in FIG. 1 is a schematic configuration diagram of an example of an image forming apparatus using a transfer roller (transfer roller) 20. The same components as those of the image forming apparatus of FIG.
The same reference numerals are given to members and portions, and the description will not be repeated.

In the present embodiment, the intermediate transfer roller 20 is formed by uniformly dispersing fine carbon or metal powder in aramid resin, polycarbonate, or fluorine resin on the outer periphery of a pipe-shaped core 21 to reduce the volume efficiency by 10%. ⁷ to 10 ¹⁰ Ω
The one covered with the resistance layer 22 adjusted to cm was used.

The peripheral length of the intermediate transfer roller 20 is set to be slightly larger than the length of the transfer material sheet 24. In this embodiment, the transfer material sheet 24 is A4 size and is used by being longitudinally fed. Is an outer diameter of 100 mm and a circumference of 31
4 mm, and the resistance layer 22 was set to have a thickness of 100 μm.

The intermediate transfer roller 20 is provided in parallel with the photosensitive drum 1 so as to be in contact with the lower surface of the photosensitive drum 1 and rotates counterclockwise as indicated by the arrow.

Reference numeral 25 denotes a transfer roller which is provided in parallel with the intermediate transfer roller 20 so as to be in contact with the lower surface of the intermediate transfer roller 20 and rotates clockwise as indicated by an arrow.

The transfer roller 25 is made of a carbon-dispersed EPDM foam material (volume resistivity of about 10 ⁹ Ω · cm) on the outer periphery of the core metal 26.
Is provided as an elastic layer 27 and has an Asker C hardness of 4
The thing of 0 degrees or less was used.

The process of sequentially forming the first to fourth color toner images on the photosensitive drum 1 is the same as that of the apparatus shown in FIG. The toner is a non-magnetic toner having a volume average particle diameter of 5 to 8 μm.
Component toner having a specific charge of -8 to -18 [mu] c / gr.
Was used.

The first to fourth color toner images are sequentially superimposedly transferred from the photosensitive drum 1 to the outer peripheral surface of the intermediate transfer roller 20 by applying a first bias power supply 61 to the metal core 21 of the intermediate transfer roller 20 to the intermediate transfer roller. Polarity opposite to toner (+)
This is performed in a state where the transfer bias is applied. The applied voltage is +2 KV to +5 KV in this example.

In this embodiment, during the transfer process, the transfer roller 25 is kept apart from the intermediate transfer roller 20 in a non-contact state, so that the toner image on the intermediate transfer roller 20 is not disturbed.

Reference numeral 8 denotes a cleaning device for the intermediate transfer roller 20, which is normally kept in a non-operating state in a non-contact state with the intermediate transfer roller 20.

The intermediate transfer roller 20 is configured to rotate by 0.5% faster than the peripheral speed of the photosensitive drum 1.
As a result, the toner image on the photosensitive drum 1 is efficiently transferred onto the intermediate transfer roller 20, and "missing" is prevented.

The transfer of the first to fourth color toner images sequentially superimposed and transferred from the photosensitive drum 1 side to the intermediate transfer roller 20 side onto the transfer material 24 precedes the leading end of the toner image on the intermediate transfer roller 20. The transfer roller 25 is
, And a transfer bias voltage having a polarity (+) opposite to that of the toner is applied to a core metal 26 of the transfer roller 25 from a bias power supply 28.

Next, the intermediate transfer roller 20 and the transfer roller 2
The transfer material 24 enters the press-contact nip n with the transfer material 2 and the transfer material 2
The transfer of the toner image on the intermediate transfer roller 20 side is performed on the surface 4.

The appropriate voltage value of the transfer bias for the core metal 26 of the transfer roller 25 changes according to the transfer voltage value applied to the core metal 21 of the intermediate transfer roller 20.

More specifically, when the transfer bias of the transfer roller 25 with respect to the core metal 26 is larger than the transfer bias applied to the core metal 21 of the intermediate transfer roller 20 by an absolute value of about 2 to 4 KV, good transfer is obtained. .

In this embodiment, when the toner image is transferred from the intermediate transfer roller 20 to the transfer material 24, the intermediate transfer roller 20
Since the voltage applied to the core metal 21 of the transfer roller 25 is +500 V, the voltage applied to the core metal 26 of the transfer roller 25 is 3 KV
Set to.

In this embodiment, the peripheral speed of the transfer roller 25 is 0.5% more than the peripheral speed of the intermediate transfer roller 20.
By rotating the transfer member 24 at a high speed, the transfer speed of the transfer material 24 is set higher than the peripheral speed of the intermediate transfer roller 20. Thereby, the transfer of the toner image from the intermediate transfer roller 20 side to the transfer material 24 side is also efficiently transferred, and the dropout is prevented.

Accordingly, from the photosensitive drum 1 to the intermediate transfer member 20
The transfer of the toner image can be prevented while preventing the image from dropping out to the transfer material 24 through the transfer.

In this embodiment, the toner image on the photosensitive drum 1 extends about 1.5% on the transfer material 24 in the sheet conveying direction. The printing magnification is adjusted by reducing the size by 0.5%.

When the toner image on the photosensitive drum 1 is transferred to the intermediate transfer roller 20, the potential of the non-image portion is different from the potential of the toner image portion. Is larger than the potential difference between the non-image portion and the non-image portion.

This tendency is conspicuous when the resistance value of the intermediate transfer roller 20 is low. For example, when the current value to the non-image portion is more than twice the current value to the toner image portion, the non-image portion The electric field has an effect on the toner image, and the toner image has "blur" around. That is, the low-resistance roller 20 is not suitable for an intermediate transfer member.

On the other hand, in the case of a roller having a high resistance, the electric field that can be generated by the bias power supply 61 becomes too small, and the intermediate transfer itself is impaired.

Therefore, a roller having a medium resistance in the range of 10 ⁵ to 10 ¹¹ Ω · cm, preferably 10 ⁷ to 10 ¹⁰ Ω · cm is suitable for the intermediate transfer member. If the elastic volume 22 having a volume resistance value in this range is used, the above-described appropriate transfer current value can be set by applying +2 to +5 KV to the metal core 21.

The transfer material 24 to which the toner image has been transferred at the pressure nip n is introduced into the fixing device 15.

When the transfer material 24 passes through the pressure nip n, the core metal 21 of the intermediate transfer roller 20 and the transfer roller 25
Are switched to biases of the same polarity (-) as the toner, respectively.

By this bias switching, the transfer residual toner on the surface of the intermediate transfer roller 20 is returned to the surface of the photosensitive drum 1 and collected by the cleaning device 14, whereby the surface of the intermediate transfer roller 20 is cleaned.

The toner adhering to the transfer roller 25 is also returned to the surface of the intermediate transfer roller 20 and further returned to the surface of the photosensitive drum 1 and collected by the cleaning device 14, whereby the transfer roller 25 is cleaned.

As described above, the intermediate transfer roller 20 has the elastic layer 2
2 is a medium resistance, the transfer residual toner can be sufficiently returned to the photosensitive drum 1 side by transfer of a bias (cleaning bias) having the same polarity as the toner to transfer the toner to the photosensitive drum 1 side to be in a cleaning state. It is not necessary, and the device configuration can be simplified.

The intermediate transfer roller 20 is driven by a core 21
And a gear (not shown) provided integrally with the intermediate transfer member, and does not require a complicated structure such as a belt deviation preventing mechanism as in the case where the intermediate transfer member is the belt 5 (FIG. 7). Can be simplified.

Here, a description will be given of the effect of preventing dropout due to the peripheral speed difference performed in the present embodiment. FIG. 2 shows the peripheral speed of the intermediate transfer roller 20 when the peripheral speed of the photosensitive drum 1 is set to 100 and the level of the hollow portion. As is clear from the figure, it is found that the level of the hollow is improved by providing the peripheral speed difference. It is considered that the transfer efficiency is improved by applying a shearing force such as wiping a toner image. This tendency is caused by the transfer roller 25.
In the present embodiment, the peripheral speed of the intermediate transfer roller 20 with respect to the photosensitive drum 1 and the peripheral speed of the transfer roller 25 with respect to the intermediate transfer roller 20 are determined based on this result. Image formation was performed with each being 0.5% faster, and good results were obtained.

<Second Embodiment> In this embodiment, in the image forming apparatus of the first embodiment (FIG. 1), the peripheral speed of the intermediate transfer roller 20 is made 1% slower than that of the photosensitive drum 1 to transfer the image. The peripheral speed of the roller 25 is 1.5 times that of the intermediate transfer roller 20.
% Faster. The effect of this is to prevent an omission at the time of intermediate transfer and at the time of transfer, and to have an effect of correcting the contraction or expansion of the toner image.

That is, when the toner image formed on the photosensitive drum 1 is transferred to the intermediate transfer roller 20, the transfer image is formed by being reduced by 1% due to a difference in peripheral speed. If the transfer roller 25 is rotated 1.5% faster when transferring this image to the transfer material 24, the transfer material 24 is actually intermediate between the intermediate transfer roller 20 and the transfer roller 25 having a larger frictional force. The image is conveyed at a speed approximately 1% faster than that of the transfer roller 20, so that the image finally formed on the transfer material 24 can be made to be the same size as the image formed on the photosensitive drum 1. Because of this effect, it is possible to provide a relatively large peripheral speed difference, and there is an advantage that the hollowing out prevention effect is correspondingly strong.

<Third Embodiment> (FIGS. 3 to 5) In the apparatus (FIG. 1) of the first embodiment, the intermediate transfer roller 2 is used.
The transfer of the toner image from 0 to the transfer material 24 is performed by feeding the transfer material 24 to a press nip n between the intermediate transfer roller 20 and a transfer roller 25 provided in pressure contact with the intermediate transfer roller 20. Then, as shown in FIG. 2, the photosensitive drum 1 and the intermediate transfer roller 2
The transfer material 24 is fed to the transfer nip portion N where the transfer roller 24 is zero, and the transfer roller 25 is not required.

The first superimposed transfer of the toner images of the first to fourth colors from the photosensitive drum 1 side to the intermediate transfer roller 20 side is performed by the first bias power supply 6 with respect to the metal core 21 of the intermediate transfer roller 20.
This is executed by applying a transfer bias having a polarity (+) opposite to that of the toner from 1.

From the intermediate transfer roller 20 side, the feeding transfer material 24
In the transfer of the toner image to the side, the bias power for the core 21 of the intermediate transfer roller 20 is switched from the first bias power 61 to the second bias power 62 as shown in the model diagram of FIG. This is performed by applying a bias voltage having the same polarity (−) as that of the above.

[0061] As in FIG. 5 in the case of monochrome printing, without transferring the photosensitive drum 1 side of the toner image (single-color toner image) t _a to the intermediate transfer roller 20, the photosensitive drum 1 and the intermediate transfer roller 20 The transfer material 24 is fed to the transfer nip N at a predetermined timing, and the core 21 of the intermediate transfer roller 20 is exposed by applying a transfer bias of the opposite polarity (+) to the toner from the first bias power supply 61. transfer t _b to the transfer sheet 24 side of the toner image t _a of the drum 1 side directly
In this case, the printing process can be shortened.

Even when the transfer material 24 exists between the photosensitive drum 1 and the intermediate transfer roller 20, the transfer current between the toner image portion and the non-image portion is unbalanced as described in the first embodiment. Since the elastic layer 22 of the roller 20 has a medium resistance, good transfer is achieved.

In both cases of FIGS. 4 and 5, the removal of the toner adhering to the intermediate transfer roller 20 after the transfer of the toner image to the transfer material 24 is performed by applying a second bias power supply 62 to the metal core 21 of the roller 20. By applying a bias voltage having the same polarity (−) as that of the toner, the toner remaining on the roller 20 is transferred back to the photosensitive drum 1 side, collected by the cleaning device 14 for the photosensitive drum 1, and the roller 20 is cleaned. .

The elastic layer 22 of the intermediate transfer roller 20 is 10 ⁷
It has a volume resistivity of 〜１０10 ¹⁰ Ω · cm.

In this embodiment, the transfer material 24 at the transfer nip N is formed by using the elastic roller 20 as the intermediate transfer member.
And the size of the apparatus is reduced, but the peripheral speed of the roller 20, which is an intermediate transfer member, is reduced by 0.5% as compared with that of the photosensitive drum 1, so that the transfer with the intermediate transfer roller 20 is performed. A speed difference is also generated between the material 24 and the intermediate member 24, so that it is possible to prevent the occurrence of the hollow during the intermediate transfer and the transfer. Although this is effective in the case of single-color transfer, there is also an advantage that the elongation of an image formed on the transfer material 24 can be reduced particularly during the four-color transfer operation.

As a further development of this embodiment, 4
Changing the peripheral speed of the intermediate transfer body between the color transfer and the intermediate transfer is also effective in preventing the hollow portion and ensuring the printing accuracy.

For example, the peripheral speed of the intermediate transfer roller 20 is increased by 0.5% in comparison with the photosensitive drum 1 at the time of intermediate transfer, and is increased by 1% at the time of transfer. Thus, the image on the transfer material 24 can be made substantially equal to the image on the photosensitive drum 1 for the same reason as described in the sixth embodiment. In addition, since a peripheral speed difference between the transfer speed of the transfer material 24 at the time of transfer and the transfer speed is sufficiently given, the effect of preventing hollowing out is increased.

<Fourth Embodiment> (FIG. 6) FIG. 6 is a schematic view of the configuration of an image forming apparatus according to the present embodiment, and shows an intermediate transfer roller 20 in comparison with the apparatus according to the third embodiment (FIG. 3). Is characterized by a small diameter.

That is, the present embodiment utilizes the expansion and contraction of an image which occurs when a speed difference is applied between the photosensitive drum 1 and the intermediate transfer member 20 and between the intermediate transfer member 20 and the transfer material 24 during the intermediate transfer and during the transfer. This is characterized in that the peripheral length of the roller 20, which is an intermediate transfer member, is shorter than the length of the transfer material 24.

That is, at the time of four-color intermediate transfer, the peripheral speed of the intermediate transfer roller 20 is set to be 50% faster than that of the photosensitive drum 1 to prevent the dropout, and the image on the intermediate transfer roller 20 is reduced by 50%. It is possible to compress it.

When transferring to the transfer material 24, the transfer material 24 is fed to the transfer nip N at the same speed as the photosensitive drum 1 by the register roller 11, and the toner image is developed to the original size. At this time, since there is a speed difference at the time of the intermediate transfer between the transfer material 24 and the intermediate transfer roller 20, the hollowing out is prevented.

In general, when the roller 20 is used as the intermediate transfer member, the peripheral length of the roller 20 is required to be equal to or longer than the length of the transfer material 24. According to the present embodiment, the peripheral length of the intermediate transfer roller 20 is reduced by half. In other words, there is an advantage that the diameter can be reduced to half and the size of the device can be reduced.

In the case of the A4 size longitudinal feed, the intermediate transfer roller 20 usually needs a diameter of 100 mm, and it is difficult to separate the intermediate transfer roller 20. However, if the means of this embodiment is used, the diameter of the intermediate transfer roller 20 is reduced. The diameter can be reduced to 50 mm, the separation is facilitated by the curvature, and the conveyance failure such as a jam can be reduced.

As described above, in the image forming apparatus in which the image formed on the first image carrier is transferred to the intermediate transfer member and further transferred to the second image carrier, the surface of the intermediate transfer member is By making the moving speed different from the surface moving speed of the first image carrier, it is possible to perform an intermediate transfer without a dropout, and furthermore, the surface moving speed of the intermediate transfer member and the surface moving speed of the second image carrier. By making the speed different from the speed, it was possible to form an image without hollow on the second image carrier. In this case, the intermediate transfer member may be of a belt type as shown in FIG.

[0075]

According to an image forming apparatus for transferring an image formed on a first image bearing member to an intermediate transfer member and further transferring the image to a second image bearing member, the surface moving speed of the intermediate transfer member is reduced to a second speed. By making the surface transfer speed different from the surface transfer speed of the first image carrier, it is possible to perform intermediate transfer without dropout, and further, the surface transfer speed of the intermediate transfer member is different from the surface transfer speed of the second image carrier. As a result, an image without a hollow was formed on the second image carrier.

[Brief description of the drawings]

FIG. 1 is a schematic diagram of an image forming apparatus according to a first embodiment.

FIG. 2 is a correlation diagram between a peripheral speed of an intermediate transfer roller and a level of image missing.

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

FIG. 4 is a model diagram of a process of transferring a synthetic color toner image from an intermediate transfer roller to a transfer material.

FIG. 5 is a schematic diagram of a transfer process in the case of a single color print.

FIG. 6 is a schematic diagram of an image forming apparatus according to a fourth embodiment.

FIG. 7 is a schematic view of an example of a conventional image forming apparatus.

FIG. 8 is a diagram of an example of an image missing portion;

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Photosensitive drum as 1st image carrier 20 Intermediate transfer roller 24 Transfer material as 2nd image carrier 25 Transfer roller

Continued on the front page (72) Inventor Hideo Nanataki 3-30-2 Shimomaruko, Ota-ku, Tokyo Canon Inc. (72) Inventor Akihiko Takeuchi 3-30-2 Shimomaruko, Ota-ku, Tokyo Canon Inc. Inside

Claims (2)

[Claims] 1. An image forming apparatus for transferring an image formed on a first image carrier onto an intermediate transfer member and further transferring the image onto a second image carrier, wherein the surface transfer of the intermediate transfer member is performed. An image forming apparatus, wherein the speed is different from the surface moving speed of the first image carrier. 2. The image forming apparatus according to claim 1, wherein a surface moving speed of the intermediate transfer member is different from a surface moving speed of the second image carrier.