JP2002169387A - Transfer device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a transfer device capable of making transfer performance compatible with cleaning performance on a high level. SOLUTION: This transfer device is equipped with an image carrier on which a toner image is carried and a transfer member press-contacting with the image carrier, and transfers the toner image to the surface of a recording medium when the carried recording medium passes through the press-contact part of the transfer member with the image carrier. The transfer member is an endless belt and is equipped with a plurality of rolls including 1st and 2nd rolls on which the endless belt is stretched and laid and a scraper press-contacting with the 2nd roll while putting the endless belt in between, and the 1st roll is equipped with at least an elastic layer and the 2nd roll is constituted of a rigid body.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a transfer device of an electrophotographic image forming apparatus such as a copying machine, a printer, a facsimile, and a multifunction machine thereof.

[0002]

2. Description of the Related Art Conventionally, as a transfer device of an electrophotographic image forming apparatus such as a copying machine or a printer, a transfer device using a transfer roll pressed against an image carrier is widely known. Then, a transfer electric field is generated between the transfer roll and the image carrier, and the toner image on the surface of the image carrier is electrostatically transferred onto a conveyed recording medium. More specifically,
There is known a configuration in which a high-hardness urethane roll or the like is used as a transfer roll, and a high-repulsion urethane blade or the like is provided opposite to the transfer roll in order to remove foreign substances such as toner attached to the surface of the transfer roll.

[0003]

However, in such a conventional transfer apparatus, it is generally difficult to achieve both high transferability and high cleaning performance. That is, if a soft transfer roll is selected in consideration of the transferability, the cleaning property is deteriorated. Conversely, if a hard transfer roll material is selected in consideration of the cleaning property, the transferability is deteriorated.

In addition, a soft transfer roll is selected in consideration of transferability, and a hard cleaning roll is provided in contact with the transfer roll in consideration of cleaning properties, and a toner such as toner transferred to the cleaning roll is provided. It is also conceivable to scrape foreign matter with a blade. However, a new problem arises in completely transferring foreign matter such as toner from the transfer roll to the cleaning roll.

The present invention has been made in view of such technical problems, and an object of the present invention is to provide a transfer device capable of achieving both high transferability and high cleaning performance.

[0006]

That is, the present invention comprises an image carrier on which a toner image is carried, and a transfer member which is pressed against the image carrier, and the recording medium to be conveyed comprises the image carrier. In a transfer device that transfers the toner image to the surface of a recording medium when passing through a pressure contact portion with a transfer member, the transfer member is an endless belt, and a first roll and a second roll that stretch the endless belt are used. And a scraper pressed against the second roll across the endless belt, the first roll includes at least an elastic layer, and the second roll is formed of a rigid body.

By configuring the transfer device in this manner, on the one hand, a relatively soft material is selected as the first roll with emphasis on transferability, and on the other hand, a relatively soft material is selected as the second roll with emphasis on cleaning performance. It is possible to provide a transfer device that is hard and has excellent transferability and cleaning performance.

Here, the first roll is softer than the second roll (that is, the second roll is harder than the first roll). The first roll may be entirely formed of an elastic body, or may be provided with at least (on its surface) an elastic layer. As the hardness of the elastic layer,
A material having an Asuka C hardness of about 10 to 80 degrees can be employed, and examples of the material thereof include urethane. On the other hand, the second roll is formed of a rigid body (at least on its surface), and examples of the material of the rigid body include metals such as stainless steel. Since the second roll is made of a rigid body as described above, the scraper (blade) pressed against the second roll may be made of a rigid body having excellent cleaning properties rather than an elastic body, for example, made of metal. preferable.

The first roll may be either a roll that follows the rotation of the endless belt (driven roll) or a roll that rotates the endless belt (drive roll). On the other hand, the second roll may be a fixed roll (fixed roll), a roll that follows the rotation of the endless belt (driven roll), or a roll that rotates the endless belt (drive roll). The material of the endless belt can be made of, for example, polyimide. Further, the electric resistance of the endless belt is preferably one having a volume resistance of 3 to 12 logΩcm under a voltage application condition of 100V.

In the transfer apparatus having such a configuration, generally,
A transfer electric field is generated between the image carrier and the first roll. At this time, it is preferable that the first roll is configured to have conductivity or semi-conductivity. The specific electric resistance value is 3 to 3 under a voltage application condition of 100 V.
Those having a volume resistance of 12 log Ωcm are preferred.

The transfer bias for generating the transfer electric field may be applied to the image carrier or may be applied to the first roll. Here, when the transfer bias is applied to the first roll, a discharge phenomenon (leakage) may occur between the first roll that stretches the endless belt and the other rolls. In particular, when a plurality of rolls are close to each other for miniaturization of the apparatus, discharge is likely to occur due to a potential difference between the rolls. Therefore, it is preferable that a voltage that does not discharge each other is applied to each of the plurality of rolls.

The image carrier may be a photoreceptor or an intermediate transfer member, and may have a drum shape or an endless belt shape.

[0013]

Embodiment FIG. 1 shows a tandem-type full-color printer (image forming apparatus) to which a transfer device according to an embodiment of the present invention is applied. In addition, the arrow in FIG. 1 has shown the rotation direction of each rotating member.

As shown in FIG. 1, this full-color printer has photosensitive drums 10 (Y) for yellow (Y), magenta (M), cyan (C), and black (K).
Image forming units 1 (Y) to (K) having
The charging rollers 11 (Y) to (K) for charging, which are in contact with the photosensitive drums 10 (Y) to (K), and the laser light L of each color.
A laser optical unit (not shown) for irradiating (Y) to (K), and a developing device 13 for visualizing (visualizing) a latent image formed on the surface of each of the photoconductor drums 10 (Y) to (K) with each color toner.
(Y) to (K) and the above four photosensitive drums 10 (Y) to
(K), the first primary intermediate transfer drum 21a in contact with two photosensitive drums 10 (K), (C) and the second primary contact in contact with the other two photosensitive drums 10 (M), (Y). A primary intermediate transfer drum 21b, a secondary intermediate transfer drum (image carrier) 22 that contacts the first and second primary intermediate transfer drums 21a and 21b, and a final transfer device that contacts the secondary intermediate transfer drum 22 (Transfer device) 3 constitutes a main part thereof.

The photosensitive drums 10 (Y) to 10 (K) are arranged at regular intervals so as to have a common tangent plane (indicated by a dashed line in the drawing) M. Also, a first primary intermediate transfer drum 21a and a second primary intermediate transfer drum 21b
Are arranged such that each rotation axis is parallel to the axes of the photoconductor drums 10 (Y) to (K) and has a plane target relation with a predetermined target plane as a boundary. Further, the secondary intermediate transfer drum 22 is arranged so that the rotation axis is parallel to the photosensitive drums 10 (Y) to 10 (K).

Signals corresponding to image information for each color are rasterized by an image processing unit (not shown) and input to a laser optical unit (not shown). In this laser optical unit, yellow (Y), magenta (M),
Laser light L of each color of cyan (C) and black (K)
(Y) to (K) are modulated, and the photosensitive drum 1 of the corresponding color is modulated.
Irradiation is performed from 0 (Y) to (K).

Around the photosensitive drums 10 (Y) to 10 (K), an image forming process for each color is performed by a known electrophotographic method. First, the photosensitive drum 10
As (Y) to (K), for example, OPC having a diameter of 20 mm
A photoconductor is used, and these photoconductor drums 10 (Y) to (K) are driven to rotate at a rotation speed of, for example, 95 mm / sec. The photosensitive drum 10 (Y)-
The surface of (K) is, as shown in FIG.
By applying a DC voltage of about -840 V to (Y) to (K), the battery is charged to about -300 V, for example. The contact-type charging device includes a roll-type charging device, a film-type charging device, and a brush-type charging device, but any type may be used. In this embodiment, a charging roll generally used in an electrophotographic apparatus in recent years is employed. Also, the photosensitive drum 1
In this embodiment, in order to charge the surface of 0 (Y) to (K), a charging method of applying only DC is used.
A charging method of C + DC application may be used.

Thereafter, the surfaces of the photosensitive drums 10 (Y) to (K) are irradiated with laser beams L (Y) to (K) corresponding to respective colors by a laser optical unit as an exposure device.
An electrostatic latent image corresponding to the input image information for each color is formed.
When an electrostatic latent image is written on the photosensitive drums 10 (Y) to 10 (K) by the laser optical unit, the surface potential of the image exposed portion is removed to about -60V or less.

The photosensitive drums 10 (Y) to (K)
Yellow (Y), magenta (M) formed on the surface of
The electrostatic latent images corresponding to the respective colors of cyan (C) and black (K) are developed by developing devices 13 (Y) to (K) of the corresponding colors, and on the photosensitive drums 10 (Y) to (K). Is visualized as a toner image of each color. In this embodiment, as the developing devices 13 (Y) to (K), a magnetic brush contact type two-component developing system is adopted. However, the application range of the present invention is not limited to this developing system. Of course, the present invention can be sufficiently applied to other developing systems such as a non-contact developing system.

Each of the developing devices 13 (Y) to (K) has a developer composed of a yellow (Y), magenta (M), cyan (C), and black (K) toner and a carrier having different colors. Is filled. These developing devices 13
In (Y) to (K), when toner is supplied from a toner supply device (not shown), the supplied toner is sufficiently stirred with the carrier by an auger (not shown) and is triboelectrically charged. Inside the developing roll, a magnet roll (not shown) having a plurality of magnetic poles arranged at a predetermined angle is arranged in a fixed state. The amount of the developer conveyed to the vicinity of the surface of the developing roll by a paddle (not shown) for conveying the developer to the developing roll is regulated by a developer amount regulating member (not shown). You. In this example,
The amount of the developer is 30 to 50 g / m ² ,
At this time, the charge amount of the toner present on the developing roll is approximately -20 to 35 [mu] C / g.

The toner supplied on the developing roll is
Due to the magnetic force of the magnet roll, a magnetic brush composed of a carrier and toner is formed, and this magnetic brush is in contact with the photosensitive drums 10 (Y) to 10 (K). An AC + DC developing bias voltage is applied to the developing roll to develop the toner on the developing roll into an electrostatic latent image formed on the photosensitive drums 10 (Y) to 10 (K), thereby forming a toner image. Is done. In this embodiment, the developing bias voltage is AC at 4 kHz, 1.5 kVpp, and DC at about -230 V.

In this embodiment, the developing device 13 (Y)
In (K), so-called “spherical toners” which are substantially spherical toners and have an average particle diameter of about 3 to 10 μm are used.

Here, as the “spherical toner”, for example, a scanning electron microscope FE-SEM (S
= 800), 100 toner images magnified at a magnification of 500 times are randomly sampled, and the image information is introduced into an image analyzer, for example, manufactured by Nicole, via an interface, and analyzed. The shape coefficient value MLS2 defined as a value obtained by calculation from the equation is 100 to 1
It is called a substantially spherical toner having a value of 40. MLS2 =
{(Absolute maximum length of toner particles) × 2} / {(projected area of toner particles) × π × １ ／ × 100} The shape of the toner produced by the ordinary kneading and pulverizing method is irregular, and MLS
2 is about 140 to 160.

Next, the photosensitive drums 10 (Y) to 10 (Y)
(K) The toner images of each color formed on the first primary intermediate transfer drum 21a and the second primary intermediate transfer drum 21
b is electrostatically secondary-transferred onto the substrate b. Photoconductor drum 10
The black (K) and cyan (C) toner images formed on (K) and (C), respectively, are both on the first primary intermediate transfer drum 21a and on the photosensitive drums 10 (M) and (Y). The magenta (M) and yellow (Y) toner images formed on the second primary intermediate transfer drum 21b are respectively (primarily) transferred.

The first and second primary intermediate transfer drums 2
The surface potential required for electrostatically transferring a toner image from the photosensitive drums 10 (Y) to 10 (K) onto 1a and 21b is as follows:
+250 to 500V. This surface potential is set to an optimum value depending on the charged state of the toner, the ambient temperature, and the humidity. The ambient temperature and the humidity can be easily known by detecting the resistance value of a member having a characteristic in which the resistance value changes depending on the ambient temperature and the humidity. As described above, when the charge amount of the toner is in the range of −20 to 35 μC / g and under the normal temperature and normal humidity environment, the first and second charge
The surface potential of the primary intermediate transfer drums 21a and 21b is +38
About 0V is desirable.

The first and second primary intermediate transfer drums 21a and 21b used in this embodiment have, for example, an outer diameter of 42 mm and a resistance value of about 10 ⁸ Ω. First,
The second primary intermediate transfer drums 21a and 21b are single-layer or multiple-layer cylindrical rotating bodies having flexible or elastic surfaces, and are generally made of metal such as Fe or Al. On a metal pipe as a core, a low-resistance elastic rubber layer (R = 10
² to 10 ³ Ω) with a thickness of about 0.1 to 10 mm. Further, the first and second intermediate transfer drums 21a, 21b
The outermost surface is typically made of a high release layer (R = 10 ⁵ to
10 ⁹ Ω) and bonded with a silane coupling agent-based adhesive (primer). The important thing here is that
It is the resistance value and the surface release property, and the resistance value of the high release layer is R =
The material is not particularly limited as long as it is about 10 ⁵ to 10 ⁹ Ω and has high releasability.

The toner images formed on the first and second primary intermediate transfer drums 21a and 21b are electrostatically (secondarily) transferred onto the secondary intermediate transfer drum 22. Therefore, on the secondary intermediate transfer drum 22, a final toner image from a single color image to a quadruple color image of yellow (Y), magenta (M), cyan (C), and black (K) is formed. Will be.

The surface potential required for electrostatically transferring a toner image from the first and second primary intermediate transfer drums 21a and 21b onto the secondary intermediate transfer drum 22 is +600 to +12.
It is about 00V. The surface potential of the photosensitive drum 10
As in the case of transferring from (Y) to (K) to the first primary intermediate transfer drum 21a and the second primary intermediate transfer drum 21b, the optimal values are set according to the charged state of the toner, the ambient temperature, and the humidity. become. What is needed for transcription is
Since it is a potential difference between the first and second primary intermediate transfer drums 21a and 21b and the secondary intermediate transfer drum 22,
It is necessary to set a value corresponding to the surface potential of the second primary intermediate transfer drums 21a and 21b. As described above, the charge amount of the toner is in the range of -20 to 35 .mu.C / g, and the surface potential of the first and second primary intermediate transfer drums 21a and 21b is +380 V under normal temperature and normal humidity environment. In this case, the surface potential of the secondary intermediate transfer drum 22 is +880 V
Degree, that is, the first and second primary intermediate transfer drums 21
It is desirable that the potential difference between the a, 21b and the secondary intermediate transfer drum 22 be set to about + 500V.

The secondary intermediate transfer drum 2 used in this embodiment
2 has an outer diameter of, for example, 42 mm, which is the same as the first and second primary intermediate transfer drums 21a and 21b, and a resistance value of 1
It is set to about 0 ¹¹ Ω. Further, the secondary intermediate transfer drum 22 also includes first and second primary intermediate transfer drums 21a and 21a.
As in b, the surface of a single layer or a plurality of layers is a cylindrical rotating body having flexibility or elasticity, and is generally placed on a metal pipe as a metal core made of Fe, Al, or the like. , A low-resistance elastic rubber layer (R = 10 ² to 10 ³ Ω) represented by conductive silicone rubber, etc., having a thickness of 0.1 to 10 mm
Provided to the extent. Further, the secondary intermediate transfer drum 22
The outermost surface is typically formed as a high release layer having a thickness of 3 to 100 μm of fluororubber in which fluororesin fine particles are dispersed, and is bonded with a silane coupling agent-based adhesive (primer). . Here, the resistance value of the secondary intermediate transfer drum 22 is determined by the first and second primary intermediate transfer drums 21a and 21a.
It must be set higher than b. Otherwise, the secondary intermediate transfer drum 22 charges the first and second primary intermediate transfer drums 21a and 21b, and it is difficult to control the surface potential of the first and second primary intermediate transfer drums 21a and 21b. Become. The material is not particularly limited as long as it satisfies such conditions.

Next, the final toner image from the single-color image to the quadruple-color image formed on the secondary intermediate transfer drum 22 is transferred onto the sheet passing through the sheet transport path P by the final transfer device 3. Next) is transcribed. This sheet passes through a sheet transport roll pair 4 through a sheet feeding step (not shown), and is sent to a nip portion between the secondary intermediate transfer drum 22 and the final transfer device 3.
After the final transfer step, the final toner image formed on the sheet is fixed by the fixing device 5 including the heating roll 50 and the pressure roll 51, and a series of image forming processes is completed.

FIG. 2 illustrates the structure of the final transfer device 3 according to the present embodiment in more detail. The final transfer device 3 includes a transfer roll (first roll) 31, a metal roll (second roll) 32, a transfer belt (endless belt) 30 stretched between these two rolls, and sandwiches the transfer belt 30. Scraper 33 pressed against metal roll 32 with
It is composed of

The transfer belt 30 is made of a polyimide resin having a thickness of about several hundred μm. This transfer belt 30
Preferably has a volume resistance of 6 to 12 log Ωcm, more preferably 9 to 11 log Ωcm under the condition of 100 V applied. In order to give such a volume resistance condition to the transfer belt 30, for example, a polyimide resin constituting the transfer belt 30 is made of an electronic conductive type material, and an appropriate amount (for example, 2 to 25%) of a volume resistance adjuster such as carbon is contained. Can be. Further, in order to improve the electric resistance maintaining property and uniformity of the polyimide resin, it is preferable to use a conductive polymer material as the conductive material of the polyimide resin. Further, the surface roughness of the transfer belt 30 may be smooth as long as an external additive of the toner is not easily adhered. For example, if the surface roughness of the ten-point average roughness Rz is about 0.3 to 1.0 μm. Good.

The transfer roller 31 urges and presses the transfer belt 30 toward the secondary intermediate transfer drum 22 from the back side of the transfer belt 30. The transfer roll 31 has, for example, an outer diameter of 20 mm and a resistance value of about 10 ⁸ Ω. As shown in FIG. 2, the transfer roll 31 is configured such that a coating layer made of urethane rubber or the like (elastic layer) is provided on a metal shaft, and a coating is applied thereon as necessary. The voltage applied to the transfer roll 31 is
The optimum value varies depending on the ambient temperature, humidity, type of paper (resistance value, etc.), and is generally about +1200 to 5000V. In this embodiment, a constant current method is employed, and a current of about +6 μA is applied in a normal temperature and normal humidity environment to obtain a substantially appropriate transfer voltage (+1600 to 2000 V).

The metal roll 32 is made of SUS as its material.
Are used. In order to reduce the frictional resistance with the transfer belt 30, the metal roll 32 is preferably configured to be rotatable, and the metal roll 33 itself is preferably driven to rotate. In this embodiment, the metal roll 3
2 is rotationally driven by a drive transmission system (not shown). It is not necessary to apply a voltage to the metal roll 32, but in order to electrostatically attach the transfer belt 30 when the metal roll 32 rotates, and to prevent leakage from the adjacent transfer roll 31. The same voltage as that of the transfer roll 31, that is, a voltage of about +1200 to 5000V is applied.

The metal scraper 33 is made of, for example, SUS as its material. In order to ensure a scraping function, it is preferable that an edge surface of the metal scraper 33 that comes into contact with the transfer belt 30 is subjected to edging. In order to reduce friction with the transfer belt 30, a metal scraper 33 is used.
It is preferable to cover a portion of the transfer belt 30 contacting with the transfer belt 30 with a low friction coat layer (for example, a fluorine coat layer). The thickness, free length, pressing pressure and the like of the metal scraper 33 can be set as appropriate. In addition, as the mounting state,
Considering the scraping performance, the metal scraper 33
Is preferably arranged in the direction in which the leading end of the transfer belt 30 (or the transfer roll 31) faces the rotation direction of the transfer belt 30, that is, in the doctor direction, and the set angle with respect to the tangent line is preferably, for example, about 15 to 45 degrees. Although not shown, a collection box for collecting toner and the like removed by the metal scraper 33 is provided so as to surround the metal scraper 33.

In a series of transfer steps (primary transfer to tertiary transfer) of the tandem type full-color printer (image forming apparatus) shown in FIG. 1, when a toner image passes through a transfer portion in each transfer step, a Paschen discharge is performed. In some cases, due to charge injection, part of the positive polarity toner in the (-) charged image becomes oppositely charged (+) charged toner. Since the (+) charged toner flows back to the upstream side without being transferred to the next process, it adheres and accumulates on the charging devices 11 (Y) to (K) having the highest negative potential. In the portions of the charging devices 11 (Y) to (K) to which the toner has adhered, the discharge becomes active, and the surface potential of the photosensitive drums 10 (Y) to (K) tends to increase. The surface potentials of the photoconductor drums 10 (Y) to (K) become uneven in a large portion, a portion with little toner adhesion, and a portion with no toner adhesion. If the surface potentials of the photoconductor drums 10 (Y) to (K) become uneven, an image is uniformly exposed on the surfaces of the photoconductor drums 10 (Y) to (K) to form an electrostatic latent image. Even so, unevenness occurs in the latent image potential, resulting in a difference in the development amount. Therefore, particularly when a halftone image is to be developed, density unevenness becomes conspicuous.

Therefore, the charging devices 11 (Y) to
In order to prevent the occurrence of density unevenness due to the toner attached to (K), in this embodiment, before printing operation, after printing operation,
The following cleaning operation is performed at a predetermined timing such as every predetermined number of sheets for continuous printing.

Charging devices 11 (Y) to (K), photosensitive drums 10 (Y) to (K), first and second primary intermediate transfer drums 21 a and 21 b, secondary intermediate transfer drum 22, final transfer roll By applying a voltage having a potential gradient to the final transfer roll 31 so that the final transfer roll 31 has the highest negative potential, the charging device 11 (Y) during the printing operation.
The (+) charged toner of the opposite polarity deposited and deposited on the transfer belt 30 is sequentially transferred to the transfer belt 30 and moved, and the metal scraper 33 provided in pressure contact with the metal roll 32 with the transfer belt 30 interposed therebetween. Collect by such as.

In this embodiment, the charging devices 11 (Y) to
(K) has a surface potential of 0 V, and the photosensitive drum 10 (Y) to
The surface potential of (K) is -300V, the surface potential of the first and second primary intermediate transfer drums 21a and 21b is -800V,
The surface potential of the secondary intermediate transfer drum 22 is set to -1300V, and the surface potential of the transfer belt 30 (transfer roll 31, metal roll 32) is set to -2000V. This potential gradient is obtained by supplying a voltage to the metal part (shaft, pipe) of each member. For example, the first and second primary intermediate transfer drums 21a and 21b or the secondary intermediate transfer drum 22 are used. If a desired surface potential can be obtained depending on the relationship between the resistance values of these members by electrically floating them, such a method may be adopted. In such a minus application cleaning mode, that is, the (+) charged toner recovery mode of the opposite polarity, it is possible to prevent the occurrence of density unevenness due to the toner attached to the charging devices 11 (Y) to (K).

It is to be noted that, if necessary, the toner is charged to the normal (-) polarity, and the photosensitive drum 10 (Y) to
(K) and the first and second primary intermediate transfer drums 21a, 21
b, and the toner remaining on the surface of the secondary intermediate transfer drum 22 can be removed by the same method (by inverting only the polarity of the applied voltage).

In the final transfer device 3 according to this embodiment, the transfer member adopts an endless transfer belt 30, so that the functions of transfer and cleaning can be easily shared.
That is, the transfer roll 31 is selected to be relatively soft with emphasis on transferability, and the metal roll 32 and the metal scraper 33 are selected to be relatively hard with emphasis on cleaning properties. Excellent cleaning performance.

Modification 1 In the embodiment, the metal roll 32 that is driven to rotate is used as the second roll. However, as shown in Modification 1, a small diameter metal roll 34 that does not rotate may be used as the second roll. By configuring the final transfer device 3 in this manner, the device can be configured to be small and simple.

Modification 2 In the final transfer device 3 according to Modification 1, only the non-rotating small-diameter metal roll 34 is used as the second roll. Can also be used. The third roll is a small-diameter roll 35 that can be driven and rotated. By configuring the final transfer device 3 in this manner, the device can be relatively small and simple, and the wrap angle of the transfer belt 30 with respect to the small-diameter metal roll 34 can be reduced, and the rotational friction resistance of the transfer belt 30 can be reduced. Can be reduced.

[0044]

As described above in detail, according to the present invention, it is possible to provide a transfer device capable of achieving both high transferability and high cleaning performance.

[Brief description of the drawings]

FIG. 1 is a schematic cross-sectional view of an image forming apparatus to which a transfer device according to an embodiment is applied.

FIG. 2 illustrates a transfer device according to the embodiment.

FIG. 3 illustrates a transfer device according to a first modification.

FIG. 4 illustrates a transfer device according to a second modification.

[Explanation of symbols]

22: secondary intermediate transfer drum (image carrier), 3: final transfer device (transfer device), 30: transfer belt (endless belt),
31: transfer roll (first roll), 32: metal roll (second roll), 33: metal scraper (scraper), 34: small diameter metal roll (second roll), 35: small diameter roll (third roll)

Continuing from the front page (72) Inventor Hiroyuki Okawa 3-7-1, Funai, Iwatsuki-shi, Saitama, F-term in Fuji Xerox Co., Ltd. Iwatsuki Office (Reference) 2H032 AA05 AA15 BA08 BA23 BA30 CA02 CA12 CA14

Claims (2)

[Claims] An image carrier that carries a toner image; and a transfer member that is pressed against the image carrier, and a recording medium that is conveyed passes through a pressure contact portion between the image carrier and the transfer member. A transfer device that transfers the toner image onto the surface of the recording medium, wherein the transfer member is an endless belt, a plurality of rolls including a first roll and a second roll that stretch the endless belt, and the endless belt. And a scraper pressed against the second roll with the first roll provided at least with an elastic layer, and the second roll is formed of a rigid body. 2. The transfer apparatus according to claim 1, wherein the plurality of rolls are applied with voltages to such an extent that they do not discharge each other.