JP3371272B2 - Transfer belt device for image forming apparatus - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image forming apparatus such as an electrophotographic copying machine and uses a transfer belt device having a rotating transfer belt to transfer a toner image obtained by developing a latent image on an image carrier. The present invention relates to a transfer belt device that transfers an electrostatic force onto recording paper by a physical means.

[0002]

2. Description of the Related Art In an image forming apparatus such as an electrophotographic copying machine, after uniformly charging a peripheral surface of a photosensitive drum, which is an image carrier, by a charger, an image is exposed on the peripheral surface of the photosensitive drum. To form an electrostatic latent image. This latent image is developed and visualized by developing means to become a toner image. The toner image formed on the peripheral surface of the photosensitive drum is transferred by a physical means onto the recording paper fed at a timing, and the recording paper on which the toner image is transferred is separated from the photosensitive drum and fixed by the fixing means. The toner image is conveyed onto the recording paper, fixed on the recording paper, and then discharged to the outside of the apparatus.

As a transfer means for transferring the toner image adhering to the peripheral surface of the photosensitive drum onto the recording paper, the toner having a polarity opposite to the charging polarity of the toner is applied by a transfer device which discharges from the back of the recording paper. The image is transferred to the recording paper,
After the transfer, a high voltage of alternating current is applied by the separator to remove the electric charge, and the recording paper is separated from the photosensitive drum. However, it is difficult to reliably maintain transferability and separability, and particularly when the drum diameter of the photoconductor drum is large, it is difficult to separate, and the recording paper after the transfer of the toner image adheres to the photoconductor drum without being separated. It has the drawback that it tends to cause paper jams. As a technique for improving this drawback, a transfer belt device as shown in FIG. 11 which is a side view of FIG. 10 or a partially enlarged view thereof is used.

The transfer belt device includes a plurality of holding rollers 33.
The transfer belt stretched by 2,333,334 is rotated at the same speed as the photosensitive drum. The transfer belt device is provided with a charge applying unit that applies an electric charge to the recording paper and causes the recording paper to be attracted to the transfer belt by an electrostatic force. And a high voltage having a polarity opposite to the toner charging polarity is applied under constant current control at the transfer portion to transfer the toner image. With such a transfer belt device, excellent transfer efficiency and separation effect can be obtained at the transfer portion.

Such a transfer belt device is used as a particularly preferable device in a color image forming device in which a toner image is superposed on a photosensitive drum and transferred onto a recording sheet at a time. In such a color image forming apparatus, since a plurality of developing devices are provided at the peripheral portion of the photoconductor drum in order to superimpose toner images on the photoconductor, the drum diameter becomes large, and sufficient separation performance cannot be obtained by the conventional electrostatic transfer separation system. Therefore, a more reliable separation performance is required, and a toner transfer amount is large in the method of superposing toner images, a large transfer charge amount is required, and thus a large transfer charge holding ability is required. This is because the transfer belt device is excellent in two respects.

However, if the transfer belt is used for a long period of time, toner, paper dust and the like will gradually adhere. Also, when a toner image on the photoconductor drum is transferred onto recording paper, if a jam occurs during transfer and corona discharge occurs without the recording paper reaching the transfer area, the toner image on the photoconductor drum Is transferred onto the transfer belt, and the transfer belt is greatly soiled. If the transfer belt is soiled, the back surface of the recording paper is soiled and the quality is deteriorated. Therefore, cleaning means for cleaning the transfer belt is required. As a cleaning means for the transfer belt, there has been used a means for cleaning a transfer belt by bringing a blade or a fur brush into contact with the transfer belt, which is well known as a method for cleaning the residual toner on the photoconductor. However, when the blade cleaning means is used, the surface of the transfer belt and the edge of the blade are worn, the cleaning performance is deteriorated, and the back surface of the recording paper is contaminated after it is jammed. There was a problem. Further, the fur brush has a problem that the capability is insufficient at the time of jamming and the like, and the removed toner is scattered.

Therefore, as disclosed in Japanese Patent Application No. 4-195453, cleaning rollers 375 and 376 are brought into contact with one of the holding rollers 332 and 333 via a transfer belt to clean the holding roller 332 or 333. A bias is applied between the rollers 375 and 376, and the positive and negative directions of the bias are reversed between the rollers adjacent to each other in the traveling direction of the transfer belt. Some of them are provided with a cleaning means for cleaning by contacting a cleaning roller through both rollers of the holding roller as disclosed in Japanese Patent Application No. 4-197165.

[0008]

However, in the conventional cleaning means as shown in FIG. 10 and its partially enlarged view of FIG. 11, the cleaning roller 375 and the holding roller 33 are used.
3. It is important from the viewpoint of cleaning property that a desired voltage is applied between both rollers while the transfer belt 331 and the transfer belt 331 are in close contact with each other.

As a means for easily realizing it, it is conceivable that the cleaning roller 375 is evenly pressed against the holding roller 333 by the biasing force of the springs on both sides and is driven by the frictional force of the transfer belt. As a result, a problem that the cleaning roller 375 itself does not rotate occurs, and it is indispensable to rotate the cleaning roller 375 directly by driving means.

However, there are the following problems when the cleaning roller 375 is rotated by the driving means.

(1) Considering the influence on the belt conveying system, it is necessary to maintain the frictional force given by the rotation of the cleaning roller 375 within a predetermined range.

The thickness of the transfer belt 331, the holding roller 3
It was necessary to strictly manage the deviation (eccentricity) of the outer diameter of 33 and the cleaning roller 375, the outer diameter tolerance, and the tolerance of the axial distance between both rollers.

The peripheral speed of the cleaning roller 375 also needs to be substantially equal to that of the transfer belt 331.

(2) The transfer belt 331 sandwiched between the cleaning roller 375 and the holding roller 333 causes an offset phenomenon of the transfer belt 331 due to a pressure difference in the axial direction generated at the sandwiching portion, and a normal belt offset prevention mechanism. It often happened that there was a big deviation that could not be prevented.

(3) Further, the conveyance speed of the transfer belt is influenced by the driving unevenness of the cleaning roller itself, which leads to the uneven rotation of the photosensitive drum 10, resulting in the problem of uneven image quality such as uneven pitch. In addition, a shift phenomenon may occur between the photoconductor drum 10 and the transfer paper P on the transfer belt 331 at the transfer portion, which may cause a problem of transfer image shift.

The present invention solves the above problems and does not affect the pitch unevenness, does not damage the transfer belt surface, can maintain the cleaning performance stably for a long time, and the shaft of the transfer belt can be maintained. It is an object of the present invention to provide a transfer belt device of an image forming apparatus that does not cause deviation in one direction or the like.

[0017]

This object is achieved by any one of the following technical means a, b, c and d.

(A) In a transfer belt device for transferring a toner image formed on a toner image carrier onto a recording material on a semiconductive transfer belt suspended by a plurality of holding rollers,
The belt is in the vicinity of the holding roller and at a position separated from the holding roller, and starts contacting with the holding roller.
Contact at a position near at wide on the surface of the belt, a potential at which the residual toner deposited on the belt with respect to the holding roller is electrostatically attracted is applied to remove said residue toner from the belt a cleaning roller for providing, the Cree
Moving the belt at the contact part of the belt with the belt
A transfer belt device of an image forming apparatus, which is rotated in a forward direction and a forward direction .

(B) Formed on the toner image carrier
Semi-conductive transfer of toner image suspended by multiple holding rollers
In the transfer belt device that transfers to the recording material on the belt,
Near the holding roller and if the belt is the holding roller
Widely contact the surface of the belt at a position separated from the
The residual toner adhering to the belt against the holding roller becomes electrostatic.
The residual toner to which a potential that is attracted is applied is
A cleaning roller for removing the
The peripheral speed of the cleaning roller is calculated from the moving speed of the belt.
Transfer belt device you characterized in that larger images forming device.

(C) Formed on the toner image carrier
Semi-conductive transfer of toner image suspended by multiple holding rollers
In the transfer belt device that transfers to the recording material on the belt,
Near the holding roller and if the belt is the holding roller
Widely contact the surface of the belt at a position separated from the belt
The toner remaining on the belt with respect to the holding roller.
The residual toner applied with a potential that electrostatically attracts
A cleaning roller to remove the
Provide the peripheral speed of the cleaning roller to move the belt
If the speed is higher than the speed,
Install the cleaning roller in the direction opposite to the belt movement direction.
Transfer belt device of images forming device characterized by rotating.

(D) Formed on the toner image carrier
Semi-conductive transfer of toner image suspended by multiple holding rollers
In the transfer belt device that transfers to the recording material on the belt,
Near the holding roller and if the belt is the holding roller
It is a position apart from and starts contacting with the holding roller.
A wide contact with the surface of the belt near its position
The residual toner adhering to the belt is electrostatically attracted to the
The residual toner applied to the belt
A cleaning roller to remove the
Set the peripheral speed of the ning roller greater than the moving speed of the belt.
Comb, the cleaning roller abuts the belt
In the transfer belt unit of images forming device characterized by rotating the moving direction and the forward direction of the belt.

[0022]

9 shows a transfer belt 331 of the transfer belt device 300, one of its holding rollers 333, and the belt 331.
FIG. 7 is a partially enlarged view for explaining the behavior of the cleaning roller 371, which comes into contact with the outside in a slightly hugged manner, attracts and absorbs the transfer toner on the belt 331 to perform cleaning.

The holding roller 333 inside the transfer belt 331 and the cleaning roller 371 on the outside are in contact with each other from the front and back of the transfer belt 331, and a potential difference between both rollers is provided to attract toner by electrostatic force to clean the belt. Such conditional expressions are derived as follows.

Total thickness of toner adhering to the transfer belt: d _t Charge amount per unit volume of toner layer: ρ _t Dielectric constant of toner layer: ε _t Linear velocity of transfer belt: ν _B Linear velocity of cleaning roller When the cleaning roller 371 is separated from the belt 331, the toner layer thickness is d _t when the peripheral speeds of the belt and the roller are equal, and υ _r when the speeds of the belt and the roller are different. _It is considered to be _B · d _t / υ _r .

[0025] Considering the field in the toner layer thickness _{D t (= υ B · d} t / υ r) at the nip just before separating from the belt, becomes as follows.

When the bias voltage of the cleaning roller at this time is V _c and the surface potential of the belt is V _B , the electric field E (X) at the point X in the toner layer thickness can be obtained by solving Poisson's equation.

That is, E (X) = (V _C −V _B ) / D _t + ρ _t / ε _t ε ₀ × (D _t / 2-X) (1) From the formula (1), the toner of the D _t layer is obtained. The condition for complete suction is E (D _t )> 0 (2), and therefore (V _C −V _B ) / D _t > ρ _t D _t / 2ε _t ε ₀ (3) or V _C −V _B > Ρ _t / 2 ε _t ε ₀ × (υ _B d _t / υ _r ) ² (4) holds.

The following two things can be said from the equation (4).

A. When the speed of the cleaning roller is increased, the amount of toner that can be cleaned and adhered to the transfer belt can be increased in proportion thereto.

That is, the cleaning property is improved proportionately.

B. Considering that V _C −V _B is determined substantially in proportion to the bias potential difference applied between the cleaning roller and the holding roller, the toner adhering to the transfer belt that can be cleaned increases in proportion to the square root of the bias potential difference. it can.

On the other hand, when the potential applied to the cleaning roller is increased, ionization occurs in the gap between the transfer belt and the cleaning roller due to the Paschen effect, and the polarity of the toner on the cleaning roller is reversed in the opposite direction. ,
There is a phenomenon that the toner once transferred is transferred in reverse. Since a spark is locally generated, a trimmer-like cleaning failure occurs, which is a serious problem.

Therefore, in the case of removing the toner transferred to the transfer belt in multiple layers as in the color image forming process, it is an idea to raise the bias voltage to improve the performance. It is easy to wake up. Therefore, it is effective to lower υ _B / υ _r in order to reduce the toner layer pressure in the separation portion and to enable cleaning with a safe bias voltage that does not cause ionization.

However, in the conventional method shown in FIGS. 10 and 11 in which the transfer belt 331 is sandwiched between the holding roller 333 and the cleaning roller 375, a slight speed difference is provided between the belt and the cleaning roller 375. in, and has become a deterioration of image quality occurs transport unevenness of the belt happened problem, υ _B / υ _r
It has been difficult to lower the cleaning efficiency to improve the cleaning property.

For this reason, a large bias voltage is applied, and the toner which cannot be cleaned and whose charge polarity has been reversed is removed by a second cleaning roller provided on the downstream side. . And the second
A bias voltage having a polarity opposite to that of the first cleaning roller was applied to the cleaning roller.

In the present invention, in order to solve the above-mentioned problems including avoiding such a Paschen effect, the contact of the cleaning roller with the transfer belt is not directly sandwiched together with the holding roller, but rather a little from the holding roller. A cleaning roller is arranged at a distant position, that is, in the vicinity of the belt separating from the holding roller or in the vicinity where the belt is about to start contact with the holding roller, and the cleaning roller is held in the belt. Has been resolved.

[0037]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described together with its operation with reference to the drawings.

FIG. 1 is a sectional view showing a schematic structure of a color laser printer equipped with a transfer belt device of an image forming apparatus of the present invention. First, based on this figure, an outline of the entire configuration and operation will be described.

The photosensitive drum 10 as an image carrier having an OPC photosensitive layer coated on its surface is in one direction (clockwise in the figure).
After being driven and rotated, the static eliminator 11 performs static elimination to remove the charge from the previous printing, and the charger 120 uniformly charges the peripheral surface to prepare for a new print. After this uniform charging, the image exposure means 13 performs image exposure based on the image signal. The image exposure means 13 rotates and scans a laser beam emitted from a laser light source, which will be described later, by a rotary polygon mirror 13A, bends an optical path by a reflection mirror 13C via an fθ lens 13B and the like, and is charged in advance with the photosensitive drum 10. A latent image is formed on the surface of the photosensitive drum 10 by being projected onto the peripheral surface of the.

On the periphery of the photoconductor drum 10, there are developed developers each composed of a mixture of toner such as yellow (Y), magenta (M), cyan (C), and black (K) and a magnetic carrier. A filled developing device 14 is provided. The toner is replenished to each developing device from the toner hopper 40 of each color through the pipes 44, 45, 46 and 47 in a timely manner. First, the development of the first color is performed by the developing sleeve 14S which has a built-in magnet and rotates while holding the developer. The developer is regulated to a predetermined thickness on the developing sleeve 14S by the layer forming rod and is conveyed to the developing area. A is provided between the photosensitive drum 10 and the developing sleeve 14S.
The C bias voltage VAC and the DC bias voltage VDC are superimposed and applied. Here, the potential of the exposed portion of the photosensitive drum 10 is VL, the surface potential of the charged photosensitive layer other than the exposed portion is VH, and the DC bias voltage VDC is | VH |> |
By setting so that VDC |> | VL | is established, the toner that is given the opportunity to be separated from the carrier by the AC bias voltage VAC has a higher potential than VDC.
It does not adhere to the H portion, but adheres to the exposed portion of potential VL lower than VDC, and is visualized and developed.

After the development of the first color is completed in this way, the image forming process of the second color (for example, magenta) is started.
The photosensitive drum 10 is uniformly charged again, and a latent image based on the image data of the second color is formed by the image exposure means 13. For the third color (cyan) and the fourth color (black), the same image forming process as for the second color is performed, and a total of four colors are developed on the photosensitive drum 10.

On the other hand, the paper feed cassette 21 or the manual feed port 24
The recording paper P, which is the transfer material fed from the paper feed mechanism 22 from the paper feeding mechanism 22, is formed between the photoconductor drum 10 and the transfer belt 331 by the transfer belt device 300 in which the transfer belt 331 is stretched. Area) 335, photoconductor drum 1
The multicolor image on the 0th circumferential surface is collectively transferred to the recording paper P. Here, a high voltage is applied to the shaft 332a of the upstream holding roller 332 of the transfer belt 331, and the transfer belt 331 is applied to the shaft 332a.
The conductive brushes 334 installed at positions facing each other with the sheet sandwiched therebetween are grounded, and the recording paper P that has been fed has the brush 334.
Between the transfer belt 331 and the transfer belt 331, and the electric charge injected into the recording paper P from the brush 334 causes the transfer belt 331 to be sucked into the transfer area. The recording paper P separated from the photoconductor drum 10 is the holding roller 3 on the downstream side which stretches the transfer belt 331.
The shaft 333b of 33 serves as a counter electrode and is separated from the transfer belt 331 while being discharged. It should be noted that the transfer belt 331 is separated from the photosensitive drum 10 about the shaft 333b of the holding roller 333 on the downstream side as a rotation center during the formation of the multicolor image.

Recording paper P separated from transfer belt device 300
Is conveyed to a fixing device 23 composed of two pressure-bonding rollers having a heater inside at least one of the rollers, and heat and pressure are applied between the two pressure-bonding rollers to melt the adhered toner. , After being fixed on the recording paper P,
It is conveyed upward through the transport guide 25 and is carried out of the apparatus.

The toner remaining on the peripheral surface of the photosensitive drum 10 after the transfer is discharged by the static eliminator 15 and then reaches the cleaning device 16 where the cleaning blade 16a contacting the photosensitive drum 10 causes the toner inside the cleaning device 16 to be removed. It is scraped off, is carried out by a screw or the like, and is stored in the collection box 17. The photoconductor drum 10 from which the residual toner has been removed by the cleaning device 16 is neutralized by the static eliminator 11 and then uniformly charged by the charger 120 to enter the next image forming cycle. If the recording paper P is not separated from the transfer belt 331 and winds around the photosensitive drum 10 and enters above the static eliminator 15, the cleaning blade 16a and the electrode wire may be damaged. A jam sensor 336 that detects wrapping at an early stage is mounted near the static eliminator 15.

Next, a first embodiment of the transfer belt device of the present invention will be described with reference to the side view of FIG. 2 and its partially enlarged view of FIG.

First, the element members constituting this embodiment will be briefly described. The drive roller 333 orbits the seamless transfer belt 331 and rotates the other holding rollers 332, 33.
Together with 4, it also functions as a holding roller that holds the belt in suspension. The surface is roughened in a satin finish to prevent slippage with the belt.

The cleaning roller 371 is a charging roller and is made of SUS material and has a surface roughness of R _{Z of} 1 μm or less.

The scraper (blade) 341 is made of PET material having a thickness of 125 μm. The straightness of the contact portion of the scraper is 100 μm or less.

The transfer belt 331 has a volume resistivity of 10 ¹⁰ to 10 ¹¹
Ωcm, surface roughness R _{Z is} 10 μm or less, and the material is a urethane rubber in which conductive carbon is dispersed as a base material and a semiconductive layer containing fluorine on the surface. The circumference of the transfer belt is 56πmm, the thickness is 0.61mm, and the Young's modulus is 450g / m.
m ² .

In the transfer belt device composed of such element members, the bias application voltage is 2 ± 0.2 kV with respect to the cleaning roller 371, and the drive roller 333 is grounded.

The orbital speed υ _B of the transfer belt 331 is 74.5.
mm / sec, cleaning roller 371 peripheral speed υ _r is 74.5 × 2.0
= 150 mm / sec (typical value).

Further, the image forming conditions are those of the Konica system in which a plurality of toner images are superposed and developed on a photosensitive member as an image carrier and transferred to a recording paper at one time, and the estimated maximum toner adhesion amount is It is estimated to be 2.5 mg / cm ² .

As shown in FIG. 3, the positional relationship between the cleaning roller 371 and the driving roller (which also functions as a holding roller) 333 is a transfer belt 331 having a roller position angle α of 20 ° on the line connecting the centers of both rollers. The gap between the inner surface of and the drive roller is 0.5 mm (typical value).

Under such conditions, the rotation direction of the cleaning roller is set to the same clockwise direction as the rotation direction of the transfer belt (the direction at the contact portion is opposite direction, referred to as a direction) and the counterclockwise direction (contact direction). (The direction of the part is called the same direction, b direction)
When the amount of toner adhered on the transfer belt which can be cleaned is determined by changing the above υ _r / υ _B with and when
The results are shown in the graph.

That is, it can be seen that the cleaning performance is superior as the speed of the cleaning roller is faster than the speed of the transfer belt, and also when the rotation direction of the cleaning roller is the direction a in the direction b.

The difference in cleaning performance between the a direction and the b direction is considered to be due to the following relationship.

That is, depending on the rotating direction of the cleaning roller 371, the effective bias voltage between the transfer belt 331 and the cleaning roller 371 in the area where the cleaning roller 371 is separated from the transfer belt 331 is different, so that the cleaning ability is different. Came out. Therefore, when the resistance value of the transfer belt 331 was lowered to approach 10 ¹⁶ Ωcm, the difference between the two almost disappeared.

That is, in the a direction, the transfer belt and the cleaning roller are separated on the entrance side of the belt where the potential difference between them is large, so that cleaning can be performed with a low bias, which is rational.

On the other hand, in the case of the b direction, in order to obtain the same high cleaning property as in the a direction, a bias voltage higher than that in the a direction is applied, and ionization occurs on the entry side.
It can be said that the reversely charged toner is likely to be generated and is relatively inferior in cleaning performance to the a direction.

Next, a second embodiment will be described with reference to the side view of FIG. 4 and its partially enlarged view of FIG.

This is a cleaning roller 372 upstream of the point where the belt 331 contacts the paper charging roller 332 which also functions as a suspension holding roller of the seamless transfer belt 331.
Is installed.

When the cleaning roller was installed under the same conditions as in the first embodiment, the cleaning performance showed a tendency almost the same as that of the first embodiment.

However, in this case, the cleaning roller 372
The cleaning performance is higher in the direction of rotation of c in the direction of d than in the direction of d. The direction of c is the direction of a in Example 1 and the direction of d is the direction of b in Example 1. It matched the performance. The result is shown in the graph of FIG.

Next, a third embodiment of the transfer belt device of the present invention will be described with reference to the side view of FIG.

This is a combination of the first and second embodiments provided with two cleaning rollers.

The following two items were experimentally confirmed in this example.

(1) The rotation direction of the first cleaning roller 371 is the a direction, the linear velocity υ _{r of the} roller 371 and the peripheral velocity υ _B of the transfer belt 331 are the same, and the rotation of the second cleaning roller 372 is the same. The direction is the c direction, and the linear velocity of the roller 372 is υ _r
And the peripheral speed υ _B of the transfer belt 331 were made the same, and the applied voltage to the first and second cleaning rollers 371 were both set to 1.5 kV.
It was found that it has the same performance as that when _r / υ _{B is set} to 2 or more.

This embodiment is useful when there is a limitation in speeding up in design.

For example, when there is not enough space in the drive mechanism by design, such a speed-up restriction is imposed, but this embodiment is effective as a means for avoiding it.

Further, since the life of the scraper (made of PET) of the cleaning roller is substantially proportional to the operating time of the cleaning roller, it may be limited in terms of the guaranteed life of the transfer belt device.

Another item (2) is (1)
The bias voltage is 2.5 kV for the first cleaning roller 371 and -1.5 kV for the second cleaning roller 372, which is almost the same as the above item.

That is, the purpose is to clean the reversely charged toner that is generated when a high bias voltage is applied.

[0073]

EFFECT OF THE INVENTION The transfer belt device of the present invention makes it possible to easily deal with the expansion and contraction of the belt.
Vibration generated in the cleaning section is greatly reduced and cleaning
As a result, it has become possible to improve the printing efficiency, and to solve the problems of the conventional electrophotographic image forming apparatus such as a copying machine, such as uneven pitch and poor transfer deviation magnification.

[0074] And apparatus that can reliably remove the color toner image not transferred on the transfer belt by click leaning roller can now be provided.

[Brief description of drawings]

FIG. 1 is a schematic sectional view of a color laser printer as an image forming apparatus in which a transfer belt device of the present invention is mounted.

FIG. 2 is a side view of an embodiment of the transfer belt device of the present invention.

FIG. 3 is a partially enlarged view of FIG.

FIG. 4 is a side view of another embodiment of the transfer belt device according to the present invention.

5 is a partially enlarged view of FIG.

FIG. 6 is a side view of another embodiment of the transfer belt device of the present invention.

FIG. 7 is a graph showing the relationship between the cleaning roller and the transfer belt speed ratio and the cleaning performance in one embodiment of the present invention.

FIG. 8 is a graph showing the relationship between the cleaning roller and the transfer belt speed ratio and the cleaning performance in another embodiment of the present invention.

FIG. 9 is an enlarged view showing the behavior of the transfer belt, the holding roller, and the cleaning roller.

FIG. 10 is a side view of a conventional transfer belt device.

11 is a partially enlarged view of FIG.

[Explanation of symbols]

300 transfer belt device 331 Transfer belt 352 Transfer pole 332 Holding roller (charging roller) 333 Holding roller (drive roller) 334 Holding roller 341, 342 Cleaning blade 371, 372, 375, 376 Cleaning roller

Claims (4)

(57) [Claims] 1. A transfer belt device for transferring a toner image formed on a toner image carrier onto a recording material on a semi-conductive transfer belt suspended by a plurality of holding rollers, in the vicinity of the holding rollers. Position where the belt is separated from the holding roller and starts contacting with the holding roller
Abuts with wide on the surface of the belt in the vicinity, a potential at which the residual toner deposited on the belt with respect to the holding roller is electrostatically attracted is applied, for removing said residue toner from the belt the cleaning roller is provided, the cleaning
The direction of movement of the grawler at the abutting part of the belt
And a transfer belt device of an image forming apparatus, which is rotated in the forward direction . 2. A toner formed on a toner image carrier.
-Semi-conductive transfer bell whose image is suspended by multiple holding rollers
In a transfer belt device that transfers to the recording material on the
The belt is separated from the holding roller in the vicinity of the holding roller.
Widely contact the surface of the belt at a position that is
The residual toner on the belt is electrostatically attracted to the roller.
The residual toner to which the potential as described above is applied
A cleaning roller to remove the
The peripheral speed of the turning roller is larger than the moving speed of the belt.
Transfer belt device of images forming device you characterized by Kushida. 3. A toner formed on a toner image carrier.
-Semi-conductive transfer bell whose image is suspended by multiple holding rollers
In a transfer belt device that transfers to the recording material on the
The belt is separated from the holding roller in the vicinity of the holding roller.
Widely abut the surface of the belt at a position separated from the belt,
The residual toner adhering to the belt with respect to the holding roller is
The residual toner to which a potential that is electrostatically attracted is applied
A cleaning roller is installed to remove it from the belt.
The peripheral speed of the cleaning roller is set to the moving speed of the belt.
Is larger than the degree, and the belt
Rotate the cleaning roller in the opposite direction of the
Transfer belt device of images forming device characterized in that makes rolling. 4. A toner formed on a toner image carrier.
-Semi-conductive transfer bell whose image is suspended by multiple holding rollers
In a transfer belt device that transfers to the recording material on the
The belt is separated from the holding roller in the vicinity of the holding roller.
A position that is a position in between and at which contact with the holding roller starts
Widely abut the surface of the belt in the vicinity and attach it to the holding roller.
On the other hand, the residual toner adhering to the belt is electrostatically attracted.
The residual toner, which has been applied with such a potential, is removed from the belt.
A cleaning roller is provided to remove the cleaning
Set the peripheral speed of the grawler greater than the moving speed of the belt.
The cleaning roller at the contact part with the belt.
Transfer belt device of images forming device you <br/> characterized by rotating the moving direction and the forward direction of the belt.