JPH0962110A - Transfer device - Google Patents

Abstract

(57) [Summary] [Problem] A belt is cracked depending on the state of the surface of a transfer belt, or the releasability of adhered toner is not good and cleaning failure of the transfer belt is caused. A transfer device 1 ′ for electrostatically transferring a magnetic toner image formed on an image carrier 3 onto a transfer material S conveyed by a transfer belt 6 ′ arranged to face the image carrier 3. 16C, a magnet roller 16C having a sleeve member 16E rotatable with respect to the outer peripheral surface 6'A of the transfer belt 6 '.
Deployed.

Description

Detailed Description of the Invention

[0001]

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

[0002]

2. Description of the Related Art In an electrophotographic image forming apparatus such as a copying machine, an image of an original is exposed after charging a photoconductor as an image carrier, or a laser scanning optical system or an LED optical writing optical system. And the like to perform optical writing in accordance with an image signal to form an electrostatic latent image on a photoconductor, develop the latent image with toner of a developing device to visualize the toner image, and transfer the toner image to a transfer material such as transfer paper. Transfer to. Then, the transfer material after the transfer is conveyed to a fixing device, and the toner image is fixed by the fixing device to obtain an image. In such an image forming apparatus, a belt type transfer device using a transfer belt is known as a device that transfers a toner image onto a transfer material and conveys the transferred transfer material to a fixing portion. The basic configuration of the transfer device and its operation will be described below.

A transfer device indicated by reference numeral 1 in FIG. 7 supports a belt unit 2 detachably from a main body 1A.
FIG. 9 shows an example of an image forming apparatus including the transfer device 1. The belt unit 2 shown in FIG. 7 includes a transfer belt 6 wound around a pair of rollers 4 and 5 for transferring a developed image from the drum-shaped photoreceptor 3 shown in FIG. DC solenoid 8 to contact and separate from
A contact / separation lever 9, a bias roller 11 that applies a transfer bias to the transfer belt 6, and a contact plate 13 that removes electric charges from the transfer belt 6. Further, the cleaning device 16 having only the cleaning blade 16A for scraping off the residual toner adhering to the surface of the transfer belt 6 and the paper waste of the transfer material S, and the high voltage power supply 12 for applying the voltage to the bias roller 11 are the main body shown in FIG. It is installed in 1A.

As shown in FIGS. 7 and 8, the roller 5 has a gear 5b connected to a drive motor (not shown) so as to be rotationally driven, and is a drive roller.
The transfer belt 6 can move in the conveying direction of the transfer material S (direction of arrow A in FIG. 9) at a position facing the photoconductor 3 by following the rotation of the roller 5. The transfer belt 6 has a two-layer structure as shown in FIG. 11, and the electric resistance measured by JISK6911 is 100 × DC, and the surface layer 6b has a surface resistivity of 1 × 10 ^{9 on the} belt surface. Ω to 1 × 10 ¹² Ω, the surface resistivity of the inner layer 6a is 1 × 10 ⁷ Ω to 1 × 10 ⁹ Ω, and its volume resistivity is 5 × 10 ⁸ Ω · cm to 5 × 10 ¹⁰ Ω.
-It is set to cm.

The rollers 4 and 5 are rotatably supported by a support 7 as shown in FIGS. The support 7 can swing about the support shaft 5 a of the roller 5 located downstream of the transfer position with respect to the photoconductor 3 in the transfer paper transport direction indicated by the arrow A among the rollers 4 and 5. . The support 7 is operated by a DC solenoid 8 driven on the transfer position side of the transfer belt 6 by a signal from a control plate 8A. That is, the DC solenoid 8
, A contact / separation lever 9 is connected, and the contact / separation lever 9 moves the support 7 to move the transfer belt 6 toward and away from the photoconductor 3.

In the control plate 8A, the front end of the transfer material S conveyed while being aligned with the front end position of the image formed on the photoconductor 3 by the registration roller 10 which is the paper conveying means is transferred to the photoconductor 3. When approaching, a drive signal is issued to drive the DC solenoid 8. Therefore, when the solenoid 8 is driven, the support 7 comes close to the photoconductor drum 3 and the transfer belt 6 comes into contact with the photoconductor 3, so that the transfer material S is exposed at a position facing the photoconductor 3. Body 3
A nip portion B that can be conveyed while being in contact with is formed (see FIG. 10).

Of the rollers 4 and 5 described above, the roller 4 located on the side of the photoconductor 3 is configured as a driven roller for the roller 5 on the drive side, and the surface shape of the roller 4 is shown in FIG. As shown, both ends 4 in the axial direction
A and 4a are formed in a tapered shape so as to prevent the transfer belt 6 from being offset. The roller 4 is a conductive roller made of metal or the like, but only supports the above-described belt having electric resistance, and is not electrically directly connected to other conductive members. Further, for the driving side roller 5, a material such as EPDM rubber, chloroprene rubber, or silicone rubber is selected because of the function of enhancing the gripping force with respect to the transfer belt 6 during driving.

The bias roller 11 is provided downstream of the roller 4 in the moving direction of the transfer belt 6 (on the left side in FIGS. 9 and 10) so as to contact the inside of the transfer belt 6. The bias roller 11 is used for the transfer belt 6
A contact electrode for applying an electric charge having a polarity opposite to the charge polarity of the toner on the photoconductor 3 to the
Connected to 2.

The contact plate 13 is disposed on the inner surface of the belt near the driven roller 4, which is the lower side of the transfer belt 6 which is not the transfer sheet conveying surface, and is transferred to the transfer material S on the upstream side of the transfer nip portion as described later. It suppresses the injection of charges. Further, the contact plate 13 is for detecting a current flowing on the transfer belt 6 as a feedback current, and the supply current from the bias roller 11 is controlled by the detection of this current. Therefore, the contact plate 13 is connected to a transfer control plate 14 for setting the current supplied to the bias roller 11 according to the detected current.
It is connected to a high voltage power supply 12.

In such a transfer device 1, at the time of image transfer, as shown in FIG. 10, the support member 7 transfers the transfer belt 6 to the photosensitive member 3 as the transfer material S is fed from the registration roller 10. A nip portion B having a width of about 4 to 8 mm, which corresponds to the length along the conveyance direction of the transfer material S, is formed between the photosensitive member 3 and the position in which the nip portion B is set to approach.

On the other hand, the surface of the photoconductor 3 is, for example,-
After being charged to 800 V, an electrostatic latent image is formed by exposure of the original image or optical writing according to the image signal, and then developed by a developing device, and the surface thereof is positively charged as shown in FIG. The magnetic toner is moved to the nip portion while being electrostatically adsorbed. The photoreceptor 3 is arranged near the photoreceptor 3 before reaching the nip portion, and its surface potential is reduced by a pre-transfer neutralization lamp (PTL) 15 that weakens the charge on the surface of the photoreceptor 3. In FIG. 12, the height of the charged electric charge is represented by the size of a circle, and the state in which the charged electric charge is reduced by the pre-transfer charge eliminating lamp 15 is as follows.
It is shown smaller than the circle that indicates before static elimination.

In the nip portion B shown in FIG. 10, the toner on the photoconductor 3 is transferred onto the transfer material S by the transfer bias from the bias roller 11 located on the transfer belt 6 side. This transfer bias is -1.5 kV to -6.5 kV.
The voltage is applied from the high voltage power supply 12 within the range described above. As a result of the constant current control described below, the transfer bias is variably set. That is, in FIGS. 9 and 10, the current value output from the high-voltage power supply 12 is I _1, and the value when the feedback current value flowing from the contact plate 13 to the ground side through the transfer belt 6 is detected is I ₂ . In this case, the value of I ₁ is controlled so that the relationship of I ₁ −I ₂ = I _OUT (where I _OUT : constant) (1) is obtained between them. this is,
This is to stabilize the surface potential V _P on the transfer material S and eliminate the change in transfer efficiency regardless of changes in environmental conditions such as temperature and humidity and variations in the manufacturing quality of the transfer belt 6. .

[0013] That is, the surface resistance of the current flowing to the photosensitive member 3 side through the transfer belt 6 and the transfer material S by Mitateru as I _{OU T,} with transfer material S (surface potential V _P)
The change in the ease of current flow to the transfer belt 6 due to the lower resistance or the higher resistance is prevented from affecting the separation performance and the transfer performance of the transfer material S. For this configuration example, I _OUT is conveying speed 330 mm / sec, the effective bias roller length 310mm, I _OUT = 35μA ± 5
Good transfer was obtained when set to μA.

Incidentally, when the toner image is transferred from the photoconductor 3, the transfer material S is also charged at the same time. Therefore, due to the relationship between the true charge of the transfer belt 6 and the polarization charge generated on the transfer material S side, the transfer material S is electrostatically adsorbed on the transfer belt 6 to separate the transfer material S from the photoconductor 3. I can do it. The separating operation is promoted by the separating operation by the stiffness of the transfer material S itself, which utilizes the curvature separation of the photoconductor 3.

However, such electrostatic attraction makes it difficult to separate the transfer material S because a current easily flows through the transfer material S at high humidity due to changes in environmental conditions.
Therefore, since the resistance value of the surface layer 6b of the transfer belt 6 shown in FIG. 11B is set to be slightly higher, the transfer of the true charge to the transfer material S at the nip portion B is delayed, Further, the bias roller 11 is located downstream of the nip portion B in the transfer paper conveyance direction. As a result, the transfer of the true charge from the transfer belt 6 to the transfer material S is delayed, and the electrostatic attraction relationship between the transfer material S and the photoconductor 3 is avoided. To delay the transfer of the true charge used in this case means that no charge is generated to the transfer material S on the upstream side until the transfer material S reaches the nip portion on the photoconductor 3 side. As a result, the transfer material S is prevented from being wound around the photoconductor 3, and also the separation failure of the transfer material S from the photoconductor 3 is prevented.

Further, for the transfer belt 6 side as well, it is better to select a material having a small resistance change due to environmental changes, and as a conductive material for controlling the resistance, carbon, zinc oxide or the like is added in an appropriate amount to form an elastic belt. When a rubber belt is used, it is desired to select a material such as chloroprene rubber, EPDM rubber, silicone rubber, and epichlorohydrin rubber that has a low hygroscopic property and a stable resistance value.
The value of the current I _OUT flowing to the side of the photoconductor 3 is not unique and can be reduced when the transport speed is slow, and conversely, when the transport speed is fast or the pre-transfer charge eliminating lamp 15 is used. If not, increase it.

On the other hand, the transfer material S passing through the nip portion B is
The electrostatic attraction and conveyance are performed in accordance with the movement of the transfer belt 6, and the curvature separation is performed by the driving side roller 5. Therefore, the diameter of the roller 5 is set to 16 mm or less. further,
In such a case of using the roller 5, fine 45K paper (stiffness transverse 21 [cm ^3/100]) experimental result that separation is possible of is obtained. Further, the transfer material S separated from the transfer belt 6 due to the curvature of the roller 5 is guided by the guide plate and conveyed between the heating roller 17a and the pad roller 17b forming the fixing unit 17. In the fixing unit 17, the toner on the transfer material S is heated and melted, and is pressed onto the transfer material S to fix the toner on the transfer material S.

After the transfer of the image onto the transfer material S and the separation of the transfer belt 6 are completed, the contact / separation lever 9 is released in response to the excitation of the DC solenoid 8 being released, and the support 7 is separated from the photoconductor 3. To be done. Then, the surface is cleaned by the cleaning device 16.

The cleaning device 16 is equipped with a cleaning blade 16A, and by rubbing the transfer belt 6, the toner transferred from the surface of the photoconductor 3 or scattered around the transfer belt 6 without being transferred. The toner and the paper dust of the transfer material S when the toner adheres are scraped off.

The transfer belt 6, which is rubbed by the cleaning blade 16A, has a low friction coefficient to prevent the increase of the driving force due to the increase of the rubbing resistance or the phenomenon such as the curling of the cleaning blade 16A. A resin material such as polyvinylidene fluoride or ethylene tetrafluoride is coated. Further, the toner or paper dust scraped off from the surface of the transfer belt 6 is stored in the waste toner collecting container (not shown) from the main body 1A by the collecting screw 16B.

[0021]

The basic structure and operation of a belt type transfer device using a transfer belt have been described above.
There are two problems.

A first problem is how to coat a material having a low coefficient of friction on a transfer belt made of an elastic elastic material. A material having a low coefficient of friction has a lower coefficient of friction as it is harder and exhibits its original properties. However, when the elastic belt is coated with the material, the tension of the belt becomes high and the material does not stretch. If the belt in this state is forcibly stretched, a crack is formed in the coating layer on the surface of the belt, and the toner enters the crack. In such a state, the toner cannot be scraped off by a cleaning blade, a brush, or the like, which causes a cleaning failure of the transfer belt surface. On the other hand, if a relatively soft material is used for the material with a low coefficient of friction so that it can follow the elastic belt, the tension of the belt will not increase so much and the occurrence of cracks will be suppressed, but the coefficient of friction on the surface of the belt will increase. As a result, the releasability of the toner is deteriorated, which also leads to poor cleaning of the transfer belt.

A second problem is that when the transfer material is separated from the transfer belt, an abnormal image in which the toner image is disturbed due to peeling discharge of the transfer material charged by the transfer is likely to occur. In particular, this abnormal image is likely to occur when the paper has a high resistance in a low humidity environment (double-sided copy, OHP sheet, etc.). As a method for preventing this, there is a method in which a corotron, a needle, and a brush are provided before the transfer material is separated from the transfer belt, and a high voltage of AC or DC is applied to remove the charged transfer material by corona discharge. In this case, ozone is generated. Further, when the applied voltage is set to 0 or a low voltage, the amount of ozone generated is reduced, but since static electricity cannot be uniformly and stably removed, the toner image disturbance at the time of peeling cannot be eliminated. The present invention has been made in view of the above circumstances, and an object of claims 1 and 2 is to provide a transfer device that more reliably cleans the surface of the transfer belt.
An object of claim 3 is to provide a configuration of a transfer device capable of solving the problem of toner image disturbance.

[0024]

In order to achieve the above object, the invention according to claim 1 forms on the image carrier on a transfer material which is conveyed by a transfer belt arranged to face the image carrier. The transfer device for electrostatically transferring the formed one-component magnetic toner image includes a magnet roller having a sleeve member rotatable with respect to the outer peripheral surface of the transfer belt. According to a second aspect of the present invention, there is provided a transfer material which is conveyed by a transfer belt formed by stretching an elastic body having at least a two-layer structure arranged opposite to the image carrier, and formed on the image carrier. A transfer device for electrostatically transferring a component magnetic toner image includes a magnet roller having a sleeve member rotatable with respect to the outer peripheral surface of the transfer belt, and a blade member contacting the outer peripheral surface of the transfer belt. . According to a third aspect of the present invention, a transfer device for electrostatically transferring a one-component magnetic toner image formed on the image carrier onto a transfer material conveyed by a transfer belt arranged to face the image carrier. In the above, a guide member having a magnet is provided on the downstream side of the separating portion between the transfer belt and the transfer material.

[0025]

Embodiments of the present invention will be described below.

FIGS. 1, 3 and 5 are views showing an example of the schematic structure of an image forming apparatus using the transfer device 1'according to the present invention. The basic structure of the transfer device is shown in FIGS. 12
The configuration is substantially the same as that shown in (the cleaning device and the transfer belt are different), and the description of the configuration and operation already described will be omitted. The toner used in the examples is a one-component magnetic toner.

1 and 2 show a transfer device 1'as a first embodiment. Transfer belt 6'in this transfer device 1 '
(Hereinafter referred to as “belt 6 ′”) is wound around the rollers 4 and 5. The belt 6'has a single-layer structure made of a rubber material as shown in FIG. 11 (a). As the rubber material, chloroprene rubber, EPDM rubber, silicone rubber, epichlorohydrin rubber and the like have little hygroscopicity,
A material having a stable resistance value is preferable.

A cleaning device 1 is provided below the roller 5.
60 are arranged. The cleaning device 160 includes a magnet roller 16C (hereinafter,
"Mag roller 16C"), a scraper 18 that is in sliding contact with the mag roller 16C, and a recovery screw 16B are arranged in the casing 16a.

The mag roller 16C is composed of a sleeve 16E which is rotationally driven in the forward direction of the transfer material indicated by an arrow A and a forward direction (direction of an arrow C) with respect to the belt surface 6'A, and a plurality of magnets 16D fixed to the roller base. It is configured. The sleeve 16E is disposed in contact with the belt outer peripheral surface 6′A, and the rotation speed ratio thereof is preferably the same as that of the belt 6 ′ or faster than that of the belt 6 ′. As a drive means for driving the sleeve 16E, a shaft 16b supporting the mag roller 16C is provided with a gear (not shown) meshing with the drive gear 5b shown in FIG. 7, or the shaft 16b is driven by a drive motor or the like not shown. If the sleeve 16E is rotatable with respect to the roller base, the sleeve 16
A gear (not shown) is provided at the end of E so as to be meshed with the drive gear 5b or driven by a drive motor. The speed ratio is adjusted by adjusting the gear ratio of these gears or adjusting the rotational speed of the drive motor.

The material of the sleeve 16E is preferably aluminum or anodized metal, and may be other non-magnetic metal. Further, although the sleeve 16E is in contact with the belt outer peripheral surface 6a here, it may be in a non-contact state by providing an interval of about 0 to 1 mm. In this case, the durability of the belt 6'is improved by being out of contact, but on the other hand, the cleaning property is slightly inferior to that in contact.

The scraper 18 is in sliding contact with the portion of the mag roller 16C located on the side opposite to the belt 6 ', and scrapes the one-component magnetic toner adsorbed by the mag roller 16C. The scraper 18 is preferably made of non-magnetic metal such as stainless steel. The recovery screw 16B is arranged below the scraper 18.

Sealing materials 19a and 19b are attached to the casing 16a located on the left and right of the mag roller 16C to prevent scattering of waste toner from the casing 16a into the apparatus.

According to the transfer device 1'having such a configuration,
The magnetic toner adhering to the belt 6 ′ is absorbed by the mag roller 16
It is transferred (adsorbed) onto the sleeve 16E by the magnetic force of C,
The scraper 18 scrapes the lower part of the casing 16a. Then, the scraped off one-component magnetic toner is collected by the collecting screw 16B into the discharged toner bottle arranged outside the unit 1A.

As described above, in the first embodiment, the magnetic toner on the belt 6'is magnetically collected by the mag roller 16C without using the conventional cleaning blade as the cleaning member for the belt 6 ', so that Wear due to sliding contact with the belt 6'is eliminated. Therefore, as shown in FIG. 11 (b), the belt outer peripheral surface 6'A does not have a low friction coefficient, but the belt durability is improved and the cleaning performance can be sufficiently ensured. Further, since the belt 6'has a rubber single-layer structure, the outer peripheral surface coating process or the like as in the conventional case is unnecessary, and the cost for the belt 6'can be reduced.

The second embodiment is shown in FIGS. In the transfer device 1'in this embodiment, the rollers 4 and 5 are arranged as shown in FIG.
The elastic belt 6a shown in (b) has a coating layer 6 having a low friction coefficient.
A transfer belt 6 having a two-layer structure (hereinafter referred to as "belt 6") provided with b is stretched and wound. The members described in the first embodiment are designated by the same reference numerals as those used in the first embodiment, and the description thereof will be omitted.

A cleaning device 1 is provided below the roller 5.
61 are arranged. The cleaning device 161 includes a sleeve 16E that is rotationally driven in the transfer material conveying direction indicated by an arrow A with respect to the belt outer peripheral surface 6A and a forward direction (direction of an arrow B), and a plurality of magnets 16D fixed to a roller base. Mag roller 16C, scraper 18 slidingly contacting mag roller 16C, cleaning blade 16A as a blade member slidingly contacting belt 6, and recovery screw 1
6B and 6B are arranged in the casing 16a.

The cleaning blade 16A is made of urethane material or the like, and is arranged upstream of the mag roller 16C in the transfer material conveying direction (on the left side in the drawing). It is supposed to scrape off the etc. On the inner surface of the belt 6, a rotatable counter roller 16F is arranged to face the mag roller 16C. The facing roller 16F is in contact with the inner peripheral surface of the belt 6, and holds the belt 6 from both sides with the mag roller 16C so that the belt 6 and the mag roller 16C are always in contact with each other.

According to the transfer device 1'having such a configuration,
The one-component magnetic toner and the paper powder attached on the belt 6 are first scraped off by the cleaning blade 16A.
Next, the one-component magnetic toner that could not be scraped off by the blade 16A is transferred to the sleeve 1 by the magnetic force of the mag roller 16C.
6E is transferred (adsorbed) onto the casing 6E and scraped by the scraper 18 to the lower portion of the casing 16a. The scraped off one-component magnetic toner is collected by the collecting screw 16B into the discharged toner bottle arranged outside the unit 1A. That is, the belt 6 is double cleaned.

As described above, in the second embodiment, since the mag roller 16C is arranged on the downstream side of the cleaning blade 16A, the belt 6 having the coating layer 6b having a low friction coefficient shown in FIG. Even if a crack is generated, the magnetic toner that has entered the crack can be adsorbed and removed by the mag roller 16C. Therefore, cleaning failure of the belt 6 can be reduced. In addition, belt 6
Is sandwiched between the opposed roller 16F and the mag roller 16C, so that even if the belt 6 sags due to a change over time, the belt 6 is always in contact with the mag roller 16C, and cleaning defects can be reduced for a long period of time. . Although the counter roller 16F is provided in the present embodiment, the counter roller 16F is not always necessary if the upward tension is applied to the belt 6 by the mag roller 16C, and as a result, the configuration of the cleaning device 161 is simplified. Can be converted.

A third embodiment is shown in FIGS. In the transfer device 1'in this embodiment, a transfer belt 60 (hereinafter referred to as "belt 60") is stretched and wound around rollers 4 and 5. The transfer belt 60 here may have a single-layer structure or a two-layer structure like the belt 6 ′ and the belt 6 described above. The vicinity of the roller 5 is a transfer material separating portion D due to the rigidity of the transfer material S itself and the curvature of the roller 5. A guide member 20 to the fixing unit 17 is arranged downstream of the separating unit D in the transfer material conveying direction indicated by the arrow A. The guide member 20 is a resin molded product such as ABS resin, PC (polycarbonate) resin, or antistatic AB.
It is made of S resin (trade name “TOYOLAC PAREL”), phenolic resin, etc. Below the guide member 20,
A plate-shaped magnet 21 is arranged. Magnet 2
1 supplies a magnetic force to the transfer material S separated from the belt 60. Here, a magnetic force having a polarity opposite to that of the magnetic toner used is applied. The magnet 21 is fixed to the casing 16 a of the cleaning device 16.

According to the transfer device 1'having such a configuration,
The transfer material S that has passed through the nip portion B is electrostatically adsorbed and conveyed in accordance with the movement of the belt 60, and is separated from the roller 5 by the curvature in the vicinity of the separation portion C. At this time, peeling discharge occurs, but since the magnetic material having a polarity opposite to that of the magnetic toner is applied to the transfer material S by the magnet 21, the magnetic toner image transferred onto the transfer material S is generated at the time of separation. Due to the peeling discharge, it is magnetically attracted to the transfer material S side and conveyed without flying. Transfer material S separated from belt 60
The toner image guided by the guide member 20 and conveyed to the fixing unit 17 and transferred is fixed on the transfer material S.

As described above, in the third embodiment, by disposing the guide member 20 having the magnet 21 on the downstream side of the separating portion C for separating the belt 60 and the transfer material S, even if peeling discharge occurs during separation, Since the magnetic force is applied to the transfer material S guided by the guide member 20, the transferred toner image is transferred to the transfer material S.
Can be adsorbed on the side. Therefore, it is possible to prevent the toner image from being disturbed due to the separation of the magnetic toner from the transfer material S.

The magnetic force applied to the transfer material S by the magnet 21 is increased when the magnet 21 is brought close to the belt 60. However, if it is too close to the belt 60, the magnetic toner adhering to the surface of the belt 60 will fly to the magnet 21 side and cause dirt on the back side.
The distance from 1 is preferably 2 mm or more. Although the magnet 21 is provided on the resinous guide member 20 here, the same effect can be obtained by using the guide member 20 made of a magnetic metal such as a steel plate and magnetizing it. In this case, since the guide member 20 and the magnet 21 can be configured by the same member, the number of parts can be reduced and the cost can be reduced.

[0044]

According to the first aspect of the present invention, since the magnet roller having the sleeve member rotatable with respect to the outer peripheral surface of the transfer belt is provided, the magnetic toner attached to the transfer belt is attracted to the magnet roller. It Therefore,
High-performance cleaning performance can be achieved without being affected by the surface characteristics of the transfer belt. Especially for magnetic toner 1
The cleaning property is improved when the component magnetic toner is used.

According to the second aspect of the invention, since the magnet roller having the sleeve member rotatable with respect to the outer peripheral surface of the transfer belt having the two-layer structure and the blade member contacting the transfer belt are provided, the blade is provided. The member can clean the magnetic toner and paper powder on the surface of the belt, and even if the belt has a crack, the magnetic toner that has entered the crack can be cleaned by the magnet roller. In particular, the cleaning property is improved when a one-component magnetic toner is used as the magnetic toner.

According to the third aspect of the invention, since the guide member having the magnet is arranged on the downstream side of the separating portion between the transfer belt and the transfer material, the magnetic toner on the transfer material is combined with the magnetic force of the magnet. The transfer material is in an adsorbed state.
Therefore, even if peeling discharge occurs when the transfer material is separated from the transfer belt, flying of the magnetic toner from the transfer material due to the discharge can be prevented, and disturbance of the toner image can be prevented. Particularly, it is effective for the disturbance of the toner image when the one-component magnetic toner is used as the magnetic toner.

[Brief description of drawings]

FIG. 1 is a schematic configuration diagram of an essential part of an image forming apparatus including a transfer device according to a first embodiment of the present invention.

FIG. 2 is an enlarged configuration diagram of a cleaning device in the transfer device shown in FIG.

FIG. 3 is a schematic configuration diagram of a main part of an image forming apparatus including a transfer device according to a second embodiment of the present invention.

FIG. 4 is an enlarged configuration diagram of a cleaning device in the transfer device shown in FIG.

FIG. 5 is a schematic configuration diagram of an image forming apparatus including a transfer device according to a third embodiment of the present invention.

6 is an enlarged configuration diagram of a cleaning device in the transfer device shown in FIG.

FIG. 7 is a perspective view showing a basic configuration of a transfer device.

FIG. 8 is an explanatory diagram of a transfer belt driving roller of a transfer device.

FIG. 9 is a schematic configuration diagram of an image forming apparatus including the transfer device shown in FIG.

FIG. 10 is a diagram showing a state of the image forming apparatus shown in FIG. 9 during transfer.

11A is a partial cross-sectional view of a transfer belt having a single-layer structure, and FIG. 11B is a partial cross-sectional view of a transfer belt having a two-layer structure.

FIG. 12 is an explanatory diagram of development and transfer steps in the image forming apparatus shown in FIGS.

[Explanation of symbols]

 1, 1'transfer device 3 image carrier (photoreceptor) 6, 6'60 transfer belt 6'A, 6A outer peripheral surface 16A blade member 16C magnet roller 16E sleeve member 20 guide member 21 magnet A transfer paper conveyance direction D separation part S transfer material

 ─────────────────────────────────────────────────── ─── Continued Front Page (72) Inventor Satoshi Takano 1-3-6 Nakamagome, Ota-ku, Tokyo, Ricoh Co., Ltd. (72) Akio Eda 1-3-6 Nakamagome, Ota-ku, Tokyo・ In Ricoh Co., Ltd. (72) Inventor Jiji Mizuishi 1-3-6 Nakamagome, Ota-ku, Tokyo ・ In Ricoh Co., Ltd. (72) Inventor Hisashi Ito 1-3-6 Nakamagome, Ota-ku, Tokyo ・Stock company Ricoh

Claims (3)

[Claims] 1. A transfer device for electrostatically transferring a one-component magnetic toner image formed on an image bearing member onto a transfer material which is conveyed by a transfer belt disposed opposite to the image bearing member. A transfer device comprising a magnet roller having a sleeve member rotatable with respect to the outer peripheral surface of the transfer belt. 2. A one-component magnetic toner formed on the image carrier on a transfer material which is conveyed by a transfer belt formed by stretching an elastic body having at least a two-layer structure arranged facing the image carrier. A transfer device for electrostatically transferring an image, comprising: a magnet roller having a sleeve member rotatable with respect to the outer peripheral surface of the transfer belt; and a blade member contacting the outer peripheral surface of the transfer belt. 3. A transfer device for electrostatically transferring a one-component magnetic toner image formed on the image carrier onto a transfer material, which is conveyed by a transfer belt arranged opposite to the image carrier. A transfer device comprising: a guide member having a magnet, which is arranged on a downstream side in a transfer paper conveyance direction with respect to a separation portion between the transfer belt and the transfer material.