JP2001188419A - Image forming device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a low cost image forming device which is small sized and high in productivity with which a high quality image can be stably obtained over a long period of time and both-side images can be automatically formed without installing an automatic both-side tray, etc. SOLUTION: An attracting means for electrostatically attracting transfer material to a photoreceptor 1 is installed on the outer periphery surface of a carrying and transferring belt 8 and is provided with an attracting member 11, and a transfer means for transferring images formed on each photoreceptor 1 sequentially to the transfer material supported on the carrying and transferring belt 8 has a transfer member 12 that is in contact with the inner periphery surface of the transfer material carrier at least during a transfer operation. Both attracting bias and transferring bias applied to the attracting member 11 and each transfer member 12, respectively, are of reverse polarity to the electrification polarity of toner and the absolute value of a control value for the attracting bias and the transfer bias are made greater toward the downstream side in a transfer material carrying path.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to an image forming apparatus for forming a full-color image, such as a full-color copying machine or a full-color printer.

[0002]

2. Description of the Related Art Various types of image forming apparatuses for forming full-color images have been put into practical use.
An image carrier is provided for each color of M (magenta), C (cyan), and Bk (black), and a full-color image is formed by sequentially transferring toner images of each color to a transfer material held on the transfer material carrier. The tandem type color image forming apparatus is capable of outputting a full-color image at a much higher speed than a transfer drum type or an intermediate transfer type color image forming apparatus having only one image carrier. There is.

However, a tandem type image forming apparatus requires the same number of charging means and transfer means as the number of image carriers, and if a corona discharge method is used as the charging means and transfer means, a large amount of discharge products such as ozone is generated. There was a problem that would occur. Further, there is a problem that the apparatus is large and the cost is likely to be high, and it is difficult to reduce the size and cost.

As a charging means and a transfer means, a contact method using a contact member such as a roller or a blade has been put to practical use instead of the conventional corona discharge method, and it is possible to greatly reduce the amount of generated discharge products. It has become possible. Thereby, even in the tandem type image forming apparatus, the charging unit,
By employing the contact method as the transfer means, it has become possible to form an image without generating a large amount of discharge products.

In such a tandem type image forming apparatus using a contact type transfer means such as a roller or a blade, the transfer means is controlled by a constant current for applying a predetermined current to the transfer member, so that the operating environment and Japanese Patent Laid-Open No. 6-1103 discloses that good transfer characteristics can be obtained even if the resistance of the transfer material changes.
No. 43, for example. In this case, when multiple transfer is sequentially performed on the transfer material, good transfer characteristics can be maintained by sequentially increasing the transfer current depending on the number of transfers.

[0006] Further, double-sided printing is demanded even in a full-color image forming apparatus for reasons such as effective use of paper resources. To perform double-sided printing with a conventional image forming apparatus, there are a method using an automatic double-sided tray and a method using a manual feed tray.

In an image forming apparatus provided with an automatic double-sided tray, first, a toner image is transferred to the first side of a transfer material, the first side is fixed by a fixing unit, and temporarily stored in the automatic double-sided tray. The transfer material stored in the tray is reversed by the reversing mechanism and fed again, the toner image is transferred to the second surface of the transfer material, and then fixed again by the fixing unit and discharged.
We are printing on both sides.

In an image forming apparatus without an automatic double-sided tray, a toner image is transferred onto a first surface of a transfer material, fixed, and then discharged, and the discharged transfer material is set on a manual feed tray by a user. To transfer and fix the second surface.

However, when an automatic double-sided tray is provided,
The cost increases accordingly. In addition, there is a problem that it is difficult to transport thick paper with the automatic double-sided tray. on the other hand,
When there is no automatic double-sided tray and the second side of the transfer material is fed using the manual tray, the operation is not easy when the number of transfer materials is large.

Further, in each case, a fixing oil adheres to the surface of the transfer material on which the toner image is formed and fixed on the first surface. When the transfer material to which the fixing oil has adhered is re-fed and the fixing oil adheres to the transfer material carrier or the image carrier, density unevenness or the like may occur, thereby deteriorating the image. Further, since the first surface passes through the fixing unit twice, the gloss may be higher than in the case of the second surface or the single-sided printing which passes the fixing unit only once.

In order to solve such a problem, Japanese Patent Application Laid-Open No. 64-44457 and Japanese Patent Application Laid-Open No. 10-232517
In Japanese Patent Application Laid-Open No. Hei 11-30881, an image forming apparatus is proposed in which a toner image is transferred onto both surfaces of a transfer material and then fixed collectively.

For example, in Japanese Patent Application Laid-Open No. Hei 10-232517, in an image forming apparatus having an intermediate transfer belt and a transfer belt, a toner image on a first surface formed on the transfer belt and a toner image formed on the intermediate transfer belt are formed. A method in which the toner image on the second surface is transferred to both surfaces of a transfer material conveyed between the intermediate transfer belt and the transfer belt, and the toner images formed on both surfaces of the transfer material are simultaneously fixed on both surfaces. I have.

In Japanese Patent Application Laid-Open No. H11-30881, after a four-color toner image is superimposed on a photosensitive member, the toner image on the first surface transferred onto a transfer belt is formed on the photosensitive member. A method is shown in which the toner image on the second surface is transferred to both surfaces of a transfer material conveyed between a photoconductor and a transfer belt, and both surfaces are simultaneously fixed.

According to these methods, since images can be formed on both sides by transferring the transfer material only once, there is no need to install an automatic double-sided tray, and the trouble of setting the transfer material on the manual tray is eliminated. In addition to this, it is possible to prevent the fixing oil from adhering to the transfer material carrier and the image carrier and deteriorating the image, and there is no difference in gloss between the first surface and the second surface.

[0015]

In order to obtain a high printing speed in a full-color image forming apparatus, a tandem system is advantageous. In recent years, image forming apparatuses using a small-diameter image carrier or a small developing device have been developed, and even a tandem-type image forming apparatus can be downsized.

In order to reduce the size of the tandem type image forming apparatus, the peripheral length of the transfer material carrier must be as short as possible. It will be located closer. In an image forming apparatus in which the suction unit and the first color transfer unit are arranged close to each other, if a bias more than necessary is applied to the suction unit, the transfer of the first color may be adversely affected.

Further, according to the above-mentioned prior art, there is no need for an automatic double-sided tray or the like, and there is no adverse effect due to the fixing oil and no difference in gloss between the first and second surfaces.
Although it is possible to obtain full-color images on both sides at low cost,
There are the following problems.

In the digital image forming apparatus disclosed in Japanese Patent Laid-Open No. Hei 10-232517, an intermediate transfer method is used.
It is not suitable for high-speed printing of full-color images. Further, the image forming apparatus disclosed in Japanese Patent Application Laid-Open No. H11-30881 can print a full-color image at a higher speed than the intermediate transfer method, but it is necessary for each color to superpose the four color toner images on the photoconductor. It is difficult to use a contact charging method as a charging method, and a non-contact corona discharge method must be used. Therefore, a large amount of discharge products such as ozone is likely to be generated.

In the case where there is no adsorbing means for adsorbing the transfer material on the transfer belt, as disclosed in JP-A-64-44457 and JP-A-10-232517, the speed at which the registration roller feeds the transfer material is described. If there is a difference between the transfer speed of the transfer transfer belt and the transfer material, the transfer material and the transfer transfer belt are shifted by the time the transfer material reaches the photosensitive member, and the image on the first surface formed on the transfer transfer belt is displaced. Will be disturbed. The speed at which the registration roller feeds out the transfer material and the speed at which the transfer belt is moved fluctuate delicately under the influence of the use environment and the like, and it is very difficult to keep both of them constant at all times.

Further, since the transfer material is transported in the horizontal direction in any of the above-mentioned prior arts, when performing double-sided printing, the leading and trailing ends of the transfer material after being separated from the transfer belt are transferred. Since it hangs down due to its own weight, an unfixed image on the first surface formed under the transfer material is likely to be in contact with a guide member or the like at a fixing entrance, thereby causing a problem that image quality is deteriorated. Has become.

In JP-A-11-30881, a spur 162 (see FIG. 1) is disposed on a transport path from separation to fixing in order to prevent such image disturbance.
However, if the spurs become dirty with toner or the like due to long-term use, the spur toner may adhere to the transfer material and degrade image quality.

In view of such circumstances, the present invention provides a small-sized, low-cost, high-productivity, high-quality image stably for a long period of time, and automatically prints both sides without an automatic double-sided tray. An object of the present invention is to provide an image forming apparatus capable of forming an image.

[0023]

In order to achieve the above object, the invention according to claim 1 comprises a plurality of image carriers, a transfer material carrier for holding and transporting a transfer material on a surface, and a transfer material. An image provided with an adsorption unit for electrostatically adhering a transfer material to a carrier and a plurality of transfer units for sequentially transferring images formed on the respective image carriers to a transfer material held on the transfer material carrier In the forming apparatus, the suction unit is disposed on the outer peripheral side of the transfer material carrier, and a suction member to which a suction bias is applied,
A transfer member that is disposed in contact with the inner peripheral surface of the transfer material carrier and is grounded, and the transfer unit has a transfer member that contacts the inner peripheral surface of the transfer material carrier at least during the transfer operation. , Suction member, suction bias applied to each transfer member,
Each of the transfer biases has a polarity opposite to the charge polarity of the toner, and the absolute values of the control values of the attraction bias and the transfer bias are set to be larger as they are further downstream in the transfer material transport path.

According to another aspect of the present invention, there is provided a semiconductor device comprising:
According to a first aspect of the present invention, in the image forming apparatus according to the first aspect,
The output current of the attraction bias and the transfer bias is controlled by a constant current.

According to another aspect of the present invention, there is provided a semiconductor device comprising:
In the image forming apparatus according to the first or second aspect, when performing double-sided printing, an image on the first surface formed on each image carrier is sequentially transferred to a transfer material carrier, and a first image is formed. An image on the surface is formed on the transfer material carrier, and the transfer material is electrostatically attracted to the transfer material carrier by the suction means, and the image on the first surface is transferred onto the transfer material. The transfer carried on the transfer material carrier The image is formed on both sides of the transfer material by sequentially transferring the image on the second surface formed on each image carrier onto the material, and the images formed on both surfaces of the transfer material are simultaneously fixed. Is what you do.

According to another aspect of the present invention, there is provided a semiconductor device comprising:
According to the invention described in the above aspect, in the image forming apparatus according to any one of the first to third aspects, the plurality of image carriers are arranged more upstream of the apparatus as the downstream side of the transfer material transport path. Things.

According to another aspect of the present invention, the above object is achieved.
According to the present invention, in the image forming apparatus according to any one of claims 1 to 4, a transport path length between a separation position where the transfer material is separated from the transfer material carrier and the fixing nip is 100 mm or less. Is what you do.

According to the first aspect of the present invention, both the attraction bias for electrostatically adhering the transfer material to the transfer material carrier and the transfer bias for transferring the toner image formed on the image carrier to the transfer material are charged. By setting the polarity and the opposite polarity so that the control values of the suction bias and the transfer bias become larger downstream of the transfer material conveyance path, the transfer material is stably conveyed, and the suction bias adversely affects the transfer. Is also prevented. Further, multiple transfer of each color to the transfer material is performed favorably.

According to the second aspect of the present invention, the suction bias,
By making the transfer bias control a constant current control, a constant and good image can be obtained regardless of the use environment and paper type.

According to the third aspect of the present invention, when performing double-sided printing, an image is formed on both sides of the transfer material using a transfer material carrier, and the images formed on both surfaces of the transfer material are simultaneously fixed. Thus, a double-sided image can be obtained without the need for an automatic double-sided tray, and defects such as uneven gloss caused by passing the paper twice are eliminated.

According to the fourth aspect of the present invention, by arranging the plurality of image carriers above the apparatus as the downstream side of the transfer material transport path, the space occupied by the apparatus is reduced and double-sided printing is performed. In this case, the unfixed image is less likely to be disturbed.

According to the fifth aspect of the present invention, the length of the conveyance path from the separation position where the transfer material is separated from the transfer material carrier to the fixing nip is shortened, thereby suppressing image disturbance.

[0033]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a schematic configuration diagram of a full-color image forming apparatus showing an embodiment of the present invention. The present image forming apparatus has four color image forming units of yellow (Y), magenta (M), cyan (C), and black (Bk).
A full-color image is formed from these four colors. The image forming units for each color include a photoconductor 1, which is an image carrier, a charging device 2, a developing device 3, a cleaning device 4, and an optical writing device 5, respectively. In FIG. 1, black (Bk)
The reference numerals of the respective units are assigned only to the image forming units of the color, but the same reference numerals are assigned to the image forming units of other colors.

The photoreceptor 1 of each color is uniformly charged by the charging device 2, and a light writing device 5 prepared for each color irradiates light in accordance with an image signal, and this light is formed on the photoreceptor 1. Thus, an electrostatic latent image is formed, and a toner image is formed by the developing device 3. The transfer belt 8 as a transfer material carrier is supported by a driving roller 9 and a driven roller 10, and moves in accordance with the rotation of the driving roller 9.

On the other hand, the transfer material set in the paper feed cassette 6 at the lower part of the apparatus is sent to the registration rollers 7 along the conveyance path, temporarily stopped, and sent out in synchronization with the operation of the image forming unit. , Suction member 1 constituting suction means
1, the toner is conveyed by being electrostatically attracted to the transfer belt 8.

The toner image formed on the photoreceptor 1 is in contact with the surface of the transfer belt 8 opposite to the surface on which the transfer material is electrostatically attracted.
2 is transferred to a transfer material. By the transfer members 12 provided for each color, the toner images formed on the photoreceptor 1 of each color are sequentially transferred onto transfer paper, and after the toner images of all colors have been transferred, the separation means 13 or the curvature separation The transfer material is separated from the transfer belt 8 by the
Is fused and pressurized to complete a full-color image,
The paper is sent to the paper discharge unit 17 at the top of the apparatus.

After the transfer material is separated from the transfer belt 8, the charge is removed by the charge removing means 15, and the cleaning means 1 is removed.
6 removes paper dust and toner adhering to the surface of the transfer belt 8 and prepares for the next image formation.

A tandem type image forming apparatus in which photoconductors are arranged in a horizontal direction as in the prior art (see FIG. 3; in FIG. 3, main parts corresponding to FIG. 1 are denoted by the same reference numerals).
In this case, the area occupied by the apparatus tends to increase. On the other hand, the plurality of photoconductors 1 are arranged above the apparatus toward the downstream of the transport path, and the transfer material is transported vertically upward as shown in FIG. Alternatively, by adopting a configuration in which the sheet is conveyed obliquely upward, the area occupied by the apparatus can be reduced.

Next, the operation when double-sided printing is performed using this image forming apparatus will be described. Similarly to the above, a toner image of the first surface is formed on the photoconductor 1 of each color,
The toner image on the first surface is sequentially transferred onto the transfer belt 8, and the transfer belt 8 on which the image on the first surface is formed continues to rotate in the forward direction.

Normally, the cleaning means 16 which is in contact with the transfer belt 8 is separated from the transfer belt 8 by the action of a not-shown contact or separation means such as a solenoid when the image on the first surface passes therethrough. The image on the first surface is prevented from being cleaned, and after passing through the image on the first surface, the image contacts the transfer belt 8 again.

The transfer material is fed and the image on the second surface is formed in synchronization with the movement of the image on the first surface. The transfer material is sent out from the registration roller 7 at the timing when the image on the first surface reaches the suction portion, and the transfer material is electrostatically suctioned to the transfer belt 8 by the suction member 11.

Here, by applying a suction bias having a polarity opposite to the charging polarity of the toner to the suction member 11, the transfer material is electrostatically suctioned to the transfer belt 8, and the image on the first surface is transferred to the transfer material. You. As the transfer material is conveyed, the images on the second surface of each color are sequentially transferred, and after the toner images of all colors are transferred, the transfer material is separated from the transfer belt 8 by the separation means 13 or curvature separation. .

The separated double-sided image is fused and fixed by a fixing device 14 to complete a full-color image on both sides. When an image is transferred to both sides of the transfer material, the image is disturbed if the transfer material contacts another member between the separation unit and the fixing unit. Therefore, by setting the interval between the separation position and the fixing nip to be short, the transfer material is supported by its own rigidity, so that the image is less likely to be disturbed.

The distance between the separation position and the fixing nip is 100 m
By setting m or less, it is possible to stably convey regardless of the paper type. In particular, if the transfer direction of the transfer material is horizontal, the leading end and the rear end of the transfer material separated from the transfer belt 8 hang down due to the weight of the transfer material itself. Is likely to reduce image quality due to contact with the device, etc., but image separation after separation occurs by setting a short distance between the separation position and the fixing nip, or by setting the conveyance direction vertically or diagonally upward. And image quality is not reduced.

When forming an image on the second side of single-sided printing or double-sided printing, a toner image of a mirror image of a target image is formed on the photoreceptor 1, and this is transferred onto a transfer material to form a normal image. However, when forming the first side of double-sided printing,
A mirror image of the target image must be formed on the transfer belt 8. Therefore, it is necessary to convert the image data into a mirror image. This conversion is performed by an image processing unit (not shown), and the converted image data is
Sent to

As described above, in the tandem type image forming apparatus, a full-color image can be formed on both sides of the transfer material only by transporting the transfer material once. Therefore, a full-color image can be output at a high speed, an automatic double-sided tray is not required, and there is no trouble of manually feeding. Further, since the transfer material once passed through the fixing device 14 is not fed again, the fixing oil does not adversely affect the image forming unit.

When performing double-sided printing, it is necessary to reliably electrostatically adsorb the transfer material to the transfer material carrier in order to prevent disturbance of the image on the first surface. FIG. 2 shows the results of an experiment conducted to investigate the relationship between the electrostatic attraction force of the transfer material, the belt resistance, and the attraction current.

In this experiment, a transfer material of A4 size was passed through the transfer belt 8 in the vertical direction, a conductive rubber roller was used as the attraction member 11, and the transfer belt 8 was electrostatically attracted. After stopping, the rear end of the transfer material is pulled in a direction opposite to the transport direction, and the force when the transfer material is displaced from the transport transfer belt 8 is measured with a force gauge.

The transfer material is 45 kg made of NBS Ricoh
Paper and 135 kg paper were used. From FIG. 2, it can be seen that as the volume resistance of the transfer belt 8 increases and as the attraction current increases, the electrostatic attraction force increases and the influence of the paper type is small. The material of the transfer conveyance belt 8 used in this experiment is a PET having a volume resistance of 1016 Ω · cm and a thickness of 75 μm.
(Polyethylene terephthalate), volume resistance 1014Ω
Cm is PVDF (polyvinylidene fluoride) having a thickness of 100 μm.

Further, an experiment was conducted with a transfer belt having a volume resistance of 1012 Ω · cm (a conductive material dispersed in PVDF and having a thickness of 100 μm), but the transfer material was transferred to the transfer belt 8 immediately after the apparatus was stopped. Is adsorbed,
Thereafter, the adsorbing force was attenuated in ten and several seconds while preparing for the adsorbing force measurement, and the adsorbing force could not be measured. Therefore, the volume resistance of the transfer belt 8 is 1012
If it is lower than Ωcm, sufficient electrostatic attraction force cannot be obtained,
The transfer material may be displaced from the transfer belt 8.

However, if the resistance is too high, a very high voltage is required to obtain sufficient transfer performance, and abnormal discharge may occur to cause an image defect. The resistance of the material used is 1012Ω
· Cm to 1016 Ω · cm is desirable. In addition to the above-mentioned PET and PVDF, PI (polyimide), PC
Resins such as (polycarbonate) and materials in which resistance is adjusted by dispersing carbon or the like in these resins can be used.

These resin films are joined to form a belt shape, or formed into a seamless belt to produce the transfer belt 8. If the thickness of the transfer belt 8 is too small, there is a problem in strength. If the thickness is too large, a higher voltage is required to obtain transfer performance.
Is desirable.

Further, a full-color image was output using an experimental machine having the following specifications. This experimental machine has a photoconductor diameter of 24 mm, a distance between drums of 78 mm, a process speed of 90 mm / s, and a paper passing width of A4 size. The photoconductor is a negative polarity OPC (organic photoconductor), the charging is a roller charging system using a conductive rubber roller, and the development is a two-component development system using a negative toner.

The transport transfer belt 8 is a PVDF belt having a thickness of 100 μm and a volume resistance of 1014 Ω · cm, and the transfer member 1
Reference numeral 2 denotes a conductive brush, which drives a conductive brush roller constituting the suction member 11 at the same speed as the transfer belt 8 in the traveling direction of the transfer material. In this experimental machine, the adsorption current was 5
By setting the μA and the transfer current to Y, M, C, and Bk of 7, 8, 9, and 10 μA respectively on the upstream side of the transport path, good transport performance without jam or color shift can be obtained regardless of the environment. A transfer rate of 90% or more was obtained for each color, and the image quality was good. In FIG. 1, the driven roller 10 corresponds to the facing member described in the claims.

[0055]

According to the first aspect of the present invention, any one of a suction bias for electrostatically adhering the transfer material to the transfer material carrier and a transfer bias for transferring the toner image formed on the image carrier to the transfer material is used. Also, by setting the polarity opposite to the charging polarity of the toner and setting the control values of the adsorption bias and the transfer bias to be larger toward the downstream side of the transfer material conveyance path, the transfer material can be stably conveyed and the suction bias is transferred. Adverse effects can be prevented. Also, multiple transfer to the transfer material of each color can be performed favorably.

According to the second aspect of the present invention, by controlling the control of the attraction bias and the transfer bias by the constant current control, it is possible to obtain a constant and good image regardless of the use environment and the type of paper.

According to the third aspect of the present invention, when performing double-sided printing, images are formed on both sides of the transfer material using the transfer material carrier, and the images formed on both surfaces of the transfer material are simultaneously fixed. By doing so, a double-sided image can be obtained without the need for an automatic double-sided tray, and problems such as uneven gloss caused by passing the paper twice can be prevented.

According to the fourth aspect of the present invention, by arranging a plurality of image bearing members above the apparatus as the downstream side of the transfer material transport path, the space occupied by the apparatus is reduced, and double-sided printing is performed. Is performed, it is possible to suppress the occurrence of disturbance of the unfixed image.

According to the fifth aspect of the present invention, the length of the conveyance path from the separation position at which the transfer material is separated from the transfer material carrier to the fixing nip can be shortened, thereby preventing image disturbance.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram of a full-color image forming apparatus showing an embodiment of the present invention.

FIG. 2 is a diagram illustrating a relationship between a belt volume resistance, a suction current, and an electrostatic suction force.

FIG. 3 is a schematic configuration diagram of a conventional image forming apparatus.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Photoconductor 8 Conveyance transfer belt 11 Suction member 12 Transfer member

────────────────────────────────────────────────── ───

[Procedure amendment]

[Submission date] January 13, 2000 (2000.1.1)
3)

[Procedure amendment 1]

[Document name to be amended] Statement

[Correction target item name] 0049

[Correction method] Change

[Correction contents]

The transfer material is 45 kg made of NBS Ricoh
Paper and 135 kg paper were used. From FIG. 2, it can be seen that as the volume resistance of the transfer belt 8 increases and as the attraction current increases, the electrostatic attraction force increases and the influence of the paper type is small. The material of the transfer conveyance belt 8 used in this experiment is a PET having a volume resistance of 10 ¹⁶ Ω · cm and a thickness of 75 μm.
(Polyethylene terephthalate), volume resistance 10 ¹⁴ Ω
cm is PVDF (polyvinylidene fluoride) having a thickness of 100 μm.

[Procedure amendment 2]

[Document name to be amended] Statement

[Correction target item name] 0050

[Correction method] Change

[Correction contents]

Further, an experiment was conducted using a transfer belt having a volume resistance of 10 ¹² Ω · cm (a conductive material dispersed in PVDF and having a thickness of 100 μm). Although the transfer material was adsorbed, the adsorbing force was attenuated in about ten seconds after preparing for the adsorbing force measurement, and the adsorbing force could not be measured. Therefore, the volume resistance of the transfer belt 8 is 10 ¹² Ω ·
If it is lower than cm, a sufficient electrostatic attraction force cannot be obtained, and the transfer material may be displaced from the transfer belt 8.

[Procedure amendment 3]

[Document name to be amended] Statement

[Correction target item name] 0051

[Correction method] Change

[Correction contents]

However, if the resistance is too high, a very high voltage is required to obtain sufficient transfer performance, and abnormal discharge may occur to cause an image defect. The resistance of the material used is 10 ¹² Ω
cm to 10 ¹⁶ Ω · cm is desirable.
In addition to T and PVDF, resins such as PI (polyimide) and PC (polycarbonate), and materials in which resistance is adjusted by dispersing carbon or the like in these resins can be used.

[Procedure amendment 4]

[Document name to be amended] Statement

[Correction target item name] 0054

[Correction method] Change

[Correction contents]

The transfer belt 8 is a PVDF belt having a thickness of 100 μm and a volume resistance of 10 ¹⁴ Ω · cm.
Uses a conductive brush, and moves a conductive brush roller that constitutes the suction member 11 in the traveling direction of the transfer material.
And the same speed. With this experimental machine, the adsorption current was 5μ.
A, by setting the transfer current to Y, M, C, and Bk of 7, 8, 9, and 10 μA, respectively, on the upstream side of the transport path, good transport performance without jam or color shift can be obtained regardless of the environment.
A transfer rate of 90% or more was obtained for each color, and the image quality was good. In FIG. 1, the driven roller 10 corresponds to the facing member described in the claims.

Claims (5)

[Claims] 1. A plurality of image carriers, a transfer material carrier for holding and transporting a transfer material on a surface, a suction unit for electrostatically adsorbing the transfer material to the transfer material carrier, and An image forming apparatus provided with a plurality of transfer means for sequentially transferring an image formed on a transfer material held on a transfer material carrier, wherein the suction means is disposed on an outer peripheral side of the transfer material support, and A biasing applying member, and an opposing member disposed in contact with the inner peripheral surface of the transfer material carrier and grounded, wherein the transfer means is at least an inner periphery of the transfer material carrier during the transfer operation. The transfer member is in contact with the surface, and the suction member, the suction bias applied to each transfer member, and the transfer bias are all opposite in polarity to the charging polarity of the toner. Larger downstream of the transfer material transport path An image forming apparatus characterized in that the image forming apparatus is set to make it easier. 2. The image forming apparatus according to claim 1, wherein the output currents of the attraction bias and the transfer bias are controlled at a constant current. 3. The image forming apparatus according to claim 1, wherein when performing double-sided printing, an image on the first surface formed on each image carrier is sequentially transferred to a transfer material carrier, and the first image is transferred to the transfer material carrier. An image on the surface is formed on the transfer material carrier, and the transfer material is electrostatically attracted to the transfer material carrier by the suction means, and the image on the first surface is transferred onto the transfer material. The transfer carried on the transfer material carrier The image is formed on both sides of the transfer material by sequentially transferring the image on the second surface formed on each image carrier onto the material, and the images formed on both surfaces of the transfer material are simultaneously fixed. Image forming apparatus. 4. The image forming apparatus according to claim 1, wherein the plurality of image carriers are arranged at a position further downstream of a transfer path of the transfer material. Image forming device. 5. The image forming apparatus according to claim 1, wherein a transport path length between a separation position where the transfer material is separated from the transfer material carrier and the fixing nip is 100 mm or less. Image forming apparatus.