JP3337577B2 - Transfer transfer device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

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

[0002]

2. Description of the Related Art In an image forming apparatus such as a copying machine, a facsimile, or a printer, a toner image is formed on an image carrier such as a photosensitive drum, and the toner image is transferred onto a transfer material such as transfer paper by a transfer device. The transfer material is transferred and separated from the image carrier, the toner image on the transfer material is fixed by a fixing device, and the image carrier is cleaned by a cleaning device after the transfer material is separated. In the duplex mode in which images are formed on both sides of the transfer material, the toner image is transferred and fixed on the front surface of the transfer material as described above, and then the toner image is similarly transferred and fixed on the back surface of the transfer material.

As a transfer device, a corona transfer method in which a toner image on an image carrier is transferred to a transfer material by applying a corona discharge to a back surface side of the transfer material by a corona charger to transfer the toner image to the transfer material, or a contact type transfer conveyance. There are devices.
The transfer transfer device of the contact type uses a transfer transfer belt or the like in which a material having a low coefficient of friction is coated on an elastic belt as a transfer unit. For example, as shown in FIG. It is stretched and rotated. At the time of transfer, the transfer / conveyance belt 11 is brought into contact with the image carrier 14 and carries and conveys a transfer material, for example, transfer paper 15 from a paper feeding device. This transfer paper 15
The transfer paper 15 is separated at the roller 12 by curvature separation due to the waist of the transfer paper 15 and is sent to a fixing device via an exit guide plate or the like. The transfer conveyance belt 11 is applied with a transfer bias to transfer the toner image on the image carrier 14 to the transfer paper 15, conveys the transfer paper 15, and has a cleaning member such as a cleaning blade 16 or a cleaning brush. It is cleaned by the cleaning device.

The transfer transfer device of the contact type has the advantages that the amount of generated ozone is small, the power supply voltage is low, and the size and cost of the device can be reduced as compared with the corona transfer method. Further, an image forming apparatus is proposed in which an intermediate conveyance unit for conveying a transfer material is provided between a transfer conveyance device having a transfer conveyance belt formed of a material having a medium resistance as a transfer unit and a fixing device. Have been.

[0005]

In the transfer / transport apparatus using the transfer / transport belt as the transfer means, a material having a low coefficient of friction, that is, a material having a low coefficient of friction, is applied to an elastic belt which is stretched when the transfer / transport belt is formed. The question is whether to coat a hard 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 a material having a low coefficient of friction is coated on an elastic belt, the tension of the transfer / transport belt becomes high and the transfer / transport belt cannot be extended. If the transfer conveyor belt in this state is forcibly extended, the coating layer on the surface of the transfer conveyor belt will be cracked, and the toner will enter the cracks, and the toner can be scraped off with a cleaning blade or a cleaning brush. However, there is a problem that cleaning failure of the surface of the transfer conveyance belt occurs.

On the other hand, if the material having a low friction coefficient is made to follow the elastic belt by coating the elastic belt with a relatively soft material as the material having a low friction coefficient, the tension of the transfer / transport belt is not so large. Although it does not increase, the generation of cracks can be suppressed, but there is a problem that the friction coefficient of the surface of the transfer conveyance belt is increased, so that the releasability of the toner is not good, and the transfer conveyance belt is also poorly cleaned. The toner remaining on the transfer conveyance belt due to such poor cleaning of the transfer conveyance belt adheres to the back surface of the next transfer material, and the toner on the back surface of the transfer material is fixed by passing the transfer material through the fixing device, and the back contamination is caused. Becomes

If there is a lot of background toner between each toner image on the image carrier, the background toner 17 is transferred to the transfer / conveying belt 11 as shown in FIG. Depending on the amount of the background toner 17, the cleaning device removes the background toner 18 on the transfer conveyance belt, and the background toner 17 adheres to the back surface of the next transfer paper 15. By passing through the fixing device, the toner on the back surface of the transfer paper 15 is fixed, and the back surface becomes dirty. The cleaning device is a cleaning blade 1
The cleaning performance also changes depending on the abrasion amount of the transfer paper 6, and the background toner 17 on the transfer conveyance belt 15 cannot be completely cleaned.
The transfer paper 15 adheres to the back surface of the transfer paper 15 and passes through the fixing device, so that the toner on the back surface of the transfer paper 15 is fixed and becomes stain on the back.

In the double-sided mode in which an image is formed on both sides of the transfer material, if the back dirt occurs on the back surface of the transfer paper 15 as described above, the background dirt toner when forming the image on the back surface of the transfer paper 15 is used. However, there is a problem that dirt on the back surface of the transfer paper becomes very noticeable due to overlap with the back dirt on the back surface of the transfer paper 15. In addition, when the amount of toner accumulated on the conveyance path such as the exit guide plate increases, when the transfer paper passes through the exit guide plate, the toner on the conveyance path rubs on the back surface of the transfer paper and adheres to the back surface of the transfer paper. In some cases, the image may be fixed by the fixing device to cause back contamination.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a transfer / conveyance apparatus which can solve the above-mentioned problems and can prevent back contamination of a transfer material.

[0010]

In order to achieve the above-mentioned object, the invention according to claim 1 is constituted by a dielectric having a resistance value including a medium resistance and being brought into contact with the image carrier to be brought into contact with the image carrier. Transfer means for transferring the toner image onto the transfer material and transporting the transfer material; drive means for driving the transfer means to rotate; charge supply means for supplying charges to the transfer means; and charge removing means for contacting the transfer means And a fixing device for fixing the toner on the transfer material is disposed downstream of the transfer material in the transfer material transport direction. The transfer device is further downstream of the transfer unit in the transfer material transport direction, and transferred from the fixing device. The cleaning device is provided with a cleaning member disposed on the upstream side in the material transport direction to clean the back side of the transfer material.

According to a second aspect of the present invention, there is provided the transfer / conveying apparatus according to the first aspect, further comprising: a bias applying means having two or more cleaning members, and applying biases having different polarities to the two or more cleaning members. It is provided with.

The invention described in claim 3 is the first or second invention.
In the transfer conveyance device described in the above, the cleaning member has a bristle brush shape.

[0013]

According to the first aspect of the present invention, the cleaning member cleans the back side of the transfer material between the transfer means and the fixing device. According to the second aspect of the present invention, in the transfer transport device according to the first aspect, a bias having a different polarity is applied to the two or more cleaning members from the bias applying unit, so that the two or more cleaning members face the back side of the transfer material. Clean. According to a third aspect of the present invention, in the transfer / transport apparatus according to the first or second aspect, the bristle brush-like cleaning member cleans the back side of the transfer material.

[0014]

2 to 4 show a first embodiment of the present invention, and FIG. 1 shows a part thereof. The first embodiment is an embodiment of the invention described in claim 1, and is an example of a transfer and conveyance device in an image forming apparatus including an electrophotographic copying machine. The transfer / conveyance device 21 of the first embodiment has a transfer / conveyance belt device 23 that is detachably supported on a copying machine main body 22. The transfer / transport belt device 23 includes a transfer unit 25 including a transfer / transport belt, which is provided below an image carrier formed of a photoconductor, for example, a photoconductor drum 24, and is formed of a dielectric having a resistance value including a medium resistance. And a driving roller 26 and a driven roller 27 for rotating the transfer conveyance belt 25 with the transfer conveyance belt 25 stretched,
A contact / separation lever 28 and a DC solenoid 29 which constitute contact / separation means for bringing the photosensitive drum 5 into and out of contact with the photosensitive drum 24; a contact electrode 30 composed of a bias roller for applying a transfer bias to the transfer / transport belt 25; A charge eliminator 31 composed of a contact plate for removing the electric charges of the charge transfer belt 25; a cleaning device 32 for cleaning the transfer / conveyance belt 25;
A cleaning device 33 for cleaning the back surface of a transfer material made of transfer paper; a high-voltage power supply 34 for applying a transfer bias to the bias roller 30; and a transfer control plate as control means for controlling the transfer bias by controlling the high-voltage power supply 34 35.

The drive roller 26 has a gear 26b connected to a drive motor, and is driven by the drive motor to rotate the transfer / transport belt 25 in a direction opposite to that of the photosensitive drum 24. Therefore, the driving roller 26 and the driving motor constitute a driving unit for driving the transfer conveyance belt 25 to rotate.
As shown in FIG. 5, the transfer / transport belt 25 includes an inner layer 25a.
And a surface layer 25b.
DC100 as the electrical resistance measured according to
When V is applied, the surface resistivity of the surface layer 25b is 1 × 1
0 ⁹ Ω to 1 × 10 ¹² Ω, and the surface resistivity of the inner layer 25a is 1
× 10 ⁷ Ω to 1 × 10 ⁹ Ω, volume resistivity is 5 ×
It is set to 10 ⁸ Ω · cm to 5 × 10 ¹⁰ Ω · cm.

The driving roller 26 and the driven roller 27 are shown in FIG.
Are rotatably supported by a support 36 as shown in FIG. The supporting member 36 is a driving roller 2 that is located on the downstream side of the nip portion B between the photosensitive drum 24 and the transfer conveyance belt 25 in the transfer paper conveyance direction A among the drive roller 26 and the driven roller 27.
6 can pivot about the support shaft a, and the contact / separation lever 28 is connected to a DC solenoid 29.

When the DC solenoid 29 is turned on / off by the control plate 37, the contact / separation lever 28 separates the transfer / conveyance belt 25 from the photosensitive drum 24 as shown in FIG. As shown in FIG. Normally, the DC solenoid 29 is turned off, and the contact / separation lever 28 separates the transfer / transport belt 25 from the photosensitive drum 24 via the support 36.

The transfer paper 38 is fed from a paper feeding device to a transfer material conveying means 39 composed of a registration roller. The registration roller 39 aligns the transfer paper 38 with the toner image on the photosensitive drum 24 by aligning the leading end thereof with the photosensitive drum. 24 and transfer conveyor belt 2
5 and sent out. When the leading end of the transfer paper 38 approaches the photosensitive drum 24, the control plate 37 controls the DC solenoid 29.
Is turned on, and the DC solenoid 29 drives the contact / separation lever 28. Then, the contact / separation lever 28 drives the support 36 to press the transfer conveyance belt 25 against the photosensitive drum 24,
A nip portion B capable of transporting the transfer paper 38 is formed at a position where the transfer transport belt 25 and the photosensitive drum 24 face each other. The driven roller 27 is, as shown in FIG.
7a is formed in a tapered shape to prevent the transfer / conveyance belt 25 from shifting.

The drive roller 26 and the driven roller 27 are conductive rollers made of metal or the like, and are electrically floating without being directly connected to other conductive members. The drive roller 26 is made of a material such as EPDM rubber, chloroprene rubber, or silicone rubber in order to increase the gripping force on the transfer conveyance belt 25 when driving the transfer conveyance belt 25. The bias roller 30 is in contact with the inside of the transfer conveyance belt 25 on the downstream side of the driven roller 27 in the movement direction of the transfer conveyance belt 25. This bias roller 3
In the case of 0, a voltage having a polarity opposite to the charging polarity of the toner on the photosensitive drum 24 is applied from the high voltage power supply 34. The contact plate 31
It is arranged near the driven roller 27 on the lower inner surface of the transfer transport belt 25 which is not the transfer paper transport surface, and suppresses charge injection to the transfer paper upstream of the nip portion B. The contact plate 31 is for detecting a return current flowing from the transfer / transport belt 25 to the ground.

In this transfer / conveyance device 21, the control plate 37 drives the DC solenoid 29 in accordance with the transfer of the transfer paper 38 from the registration roller 39, and the DC solenoid 29 drives the contact / separation lever 28, and The release lever 28 drives the support 36 to press the transfer conveyance belt 25 against the photosensitive drum 24, so that the transfer conveyance belt 25 and the photosensitive drum 24 face each other at a position facing the transfer paper 38 in the conveyance direction of about 4 to 8 mm. Is formed.

On the other hand, the photosensitive drum 24 is driven to rotate by a motor as is well known, and is charged to -800 V by a charging means.
After being uniformly charged, an electrostatic latent image is formed by exposing the original image by the exposure means, and as shown in FIG.
As a result, the electrostatic latent image is developed with a developer to become a toner image.
The developing device 40 develops a toner image on the photosensitive drum 24 by applying a developing bias voltage from a developing bias power supply and applying a developer to the photosensitive drum 24 to electrostatically attract the positively charged toner 41. I do.

Next, the photosensitive drum 24 is connected to the pre-transfer neutralizer 4.
2, the surface potential is reduced due to the charge elimination. In FIG. 8, the height of the charge of the toner is indicated by the size of a circle. The transfer conveyance belt 25 is supplied with electric charge by applying a transfer bias from a high voltage power supply 34 via a bias roller 30, and transfers the toner image on the photosensitive drum 24 when the transfer paper 38 passes through the nip portion B. The transfer paper 38 is transferred to the paper 38, and the transfer paper 38 is electrostatically attracted and separated from the photosensitive drum 24 to be conveyed.

In this case, the transfer bias is applied from the high voltage power supply 34 to the bias roller 30 in the range of -1.5 KV to -1.6 KV. The transfer bias is variably set by constant current control by the transfer control plate 35. . That is, the current output from the high-voltage power supply 34 is I ₁ ,
5 is supplied to the ground via the electrode plate 31 by I
When _2, the transfer control board 35 controls I ₁ controls the high voltage power supply 34 as I ₁ -I ₂ = Iout detects a feedback current I ₂ becomes a constant value.

This is to stabilize the surface potential Vp on the transfer paper 38 so as to eliminate the change in transfer efficiency, irrespective of changes in environmental conditions such as temperature and humidity and variations in the production quality of the transfer conveyance belt 25. In order to
In other words, the current flowing to the photosensitive drum 24 through the transfer conveyance belt 25 and the transfer paper 38 is regarded as Iout, so that the surface resistance Vp on the transfer paper 38 can be reduced or increased by increasing the surface resistance Vp. This is to prevent a change in the ease of current flow from affecting the separation performance and transfer performance of the transfer paper 38. In this embodiment, I
out is transfer paper transfer speed 330 mm / sec, effective length of bias roller 30 is 310 mm, and Iout = 35 μA ± 5 μ.
When set to A, good transfer was performed. As described above, the bias roller 30 and the high-voltage power supply 34 constitute a charge supply unit that supplies charges to the transfer conveyance belt 25.

Incidentally, the transfer paper 3 is transferred from the photosensitive drum 24 to the transfer paper 3.
When the toner image is transferred to the transfer paper 8, the transfer paper 38 is charged.
Therefore, the transfer paper 38 is electrostatically attracted onto the transfer / transport belt 25 by the relationship between the true charge of the transfer / transport belt 25 and the polarization charge generated on the transfer paper 38 side, and the photosensitive drum 24
Separated from Then, the photosensitive drum 2 of the transfer paper 38
The separation from the photosensitive drum 24 is promoted by the peeling operation from the photosensitive drum 24 due to the stiffness of the transfer paper 38 itself utilizing the curvature separation of the photosensitive drum 24. The transfer paper 38 that cannot be separated from the photosensitive drum 24 is separated from the photosensitive drum 24 by the separation claw 43.

The separation between the transfer paper 38 electrostatically adsorbed on the transfer / transport belt 25 and the photosensitive drum 24 facilitates the flow of current to the transfer paper 38 in high humidity due to changes in environmental conditions. It will not work. Therefore, by setting the surface resistance of the surface layer 25b of the transfer conveyance belt 25 to be slightly higher, the transfer of the true charges to the transfer paper 38 at the nip portion B is delayed, and the bias roller 30 is moved from the nip portion B It is located on the downstream side in the transfer paper transport direction. As a result, the transfer of the true charges from the transfer conveyance belt 25 to the transfer paper 38 is delayed, and the electrostatic attraction between the transfer paper 38 and the photosensitive drum 24 is avoided.

In this case, to delay the transfer of the true charge means
Until the transfer paper 38 reaches the nip portion B on the photosensitive drum 24 side, it means that the transfer of true charges to the transfer paper 38 does not occur on the upstream side. From this, transfer paper 3
8 is prevented from wrapping around the photosensitive drum 24, and
The separation failure of the transfer paper 38 from the photosensitive drum 24 is prevented.

Further, it is better to select a transfer / conveying belt 25 having a small resistance change due to an environmental change.
When a suitable amount of zinc oxide or the like is added and a rubber belt is used as the elastic belt, it is desirable to select a material having a low hygroscopic property and a stable resistance value, such as chloroprene rubber, EPDM rubber, silicone rubber, and epichlorohydrin rubber. It is. The value of the current Iout flowing from the transfer conveyance belt 25 to the photosensitive drum 24 is not unique, and can be reduced when the transfer paper conveyance speed is low.
Conversely, if the transfer paper transport speed is high or if the pre-transfer static eliminator 42 is not used, the number of charges increases.

The transfer paper 38 that has passed through the nip portion B is conveyed in accordance with the movement of the transfer conveyance belt 25 because it is electrostatically attracted to the transfer conveyance belt 25, and the curvature separation is performed at the drive roller 26. Will be The diameter of the drive roller 26 is set to 16 mm or less, and high-quality 45K paper (steel width 2
1 cm ^3/100) Experimental result that separation is possible of is obtained.

When the transfer paper 38 is separated from the transfer / transport belt 25, the control plate 37 releases the excitation of the DC solenoid 29, the DC solenoid 29 releases the drive of the contact / separation lever 28, and the support plate 36 The transfer / conveying belt 25 is separated from the photosensitive drum 24 while being separated from the photosensitive drum 24. Then, the surface of the transfer conveyance belt 25 is cleaned by a cleaning device 32 near the lower side of the driving roller 26. The cleaning device 32 includes a cleaning blade 44.
The cleaning blade 44 rubs the surface of the transfer / transport belt 25 so that toner transferred from the photosensitive drum 24 on the transfer / transport belt 25,
The toner and paper powder of the transfer paper that are scattered from the photosensitive drum 24 to the periphery of the transfer conveyance belt 25 without being transferred to the transfer paper are scraped off.

The transfer conveyor belt 25 rubbed by the cleaning blade 44 has a low friction coefficient to prevent a phenomenon such as an increase in driving force due to an increase in rubbing resistance or a turning-up of the cleaning blade 44. Resin material, for example, polyvinylidene fluoride, tetrafluoroethylene, etc., is coated on the surface. Further, the toner and paper dust scraped off from the transfer / transport belt 25 by the cleaning blade 44 are collected from the copying machine main body 22 to a waste toner collecting container (not shown) by the collecting screw 45.

The transfer paper 38 separated from the transfer / transport belt 25 is guided by a guide member 46 composed of an exit guide plate of the transfer / transport belt device 23 to be cleaned by the cleaning device 33.
The back surface of the fixing device 47 is conveyed between the heating roller 49 and the pad roller 50 by being guided by the entrance guide plate 48 of the fixing device 47. The heating roller 49 and the pad roller 50 fix the toner on the transfer paper 38 by applying heat and pressure. Also, the photosensitive drum 2
4 is cleaned by a cleaning device after the transfer paper is separated, and is ready for the next copying operation.

The cleaning device 33 includes a cleaning member 51 composed of a cleaning bias roller disposed between an exit guide plate 46 of the transfer / transport belt device 23 and an entrance guide plate 48 of the fixing device 47, and a cleaning bias roller A bias applying means 52 composed of a cleaning bias power supply for applying a cleaning bias voltage having a polarity opposite to the charging polarity of the toner on the photosensitive drum 24 (the same polarity as the transfer bias) to the cleaning device 51, and a cleaning device provided on a counter for cleaning A cleaning blade 53 for removing toner from the bias roller 51; The cleaning bias roller 51 is driven to rotate in a direction indicated by an arrow in FIG.

The cleaning bias roller 51 also has a function of transferring the transfer paper 38 from the exit guide plate 46 to the entrance guide plate 48 to facilitate the transfer of the transfer paper. The cleaning bias power supply 52 applies the cleaning bias voltage to the cleaning bias roller 51 at a timing slightly delayed from the timing of applying the transfer bias to the bias roller 30 from the high voltage power supply 34 as shown in FIG. The absolute value of the cleaning bias voltage applied from the cleaning bias power supply 52 to the cleaning bias roller 51 is smaller than the transfer bias voltage applied from the high voltage power supply 34 to the bias roller 30, and the toner image on the surface of the transfer paper 38. Is set so as not to disturb.

The transfer paper 38 from the exit guide plate 46 passes over the cleaning bias roller 51,
The toner 54 attached to the back surface is electrostatically cleaned by the cleaning bias roller 51. Transfer paper 3
The toner adhered to the cleaning bias roller 51 from 8 is cleaned by the cleaning blade 53 and collected by the collection screw 45 from the copying machine main body 22 to a waste toner collection container (not shown).

In the first embodiment, the transfer is performed by transferring the toner image formed on the image carrier 24 to the transfer material 38 by transferring the toner image on the image carrier 24 by contacting the image carrier 24. Means 25, a driving means 26 for rotationally driving the transfer means 25, charge supply means 30 and 34 for supplying electric charges to the transfer means 25, and a charge removing means 3 in contact with the transfer means 25
1, a fixing device 47 for fixing the toner on the transfer material 38 is disposed downstream of the transfer material conveyance direction in the transfer conveyance device 21. Since the cleaning member 51 including a cleaning bias roller that electrostatically cleans the back surface of the transfer material 38 and that is disposed on the upstream side in the transfer material transport direction with respect to the transfer material 47 is provided, the back contamination of the transfer material conveyed to the fixing device is reduced. Background dirt can be prevented, and back dirt on the transfer material can be prevented. In particular, the cleaning effect on the toner electrostatically attached to the back surface of the transfer material 38 is large.

FIG. 10 shows a second embodiment of the present invention. This second embodiment is an embodiment according to the second aspect of the present invention. Second
In the embodiment, the cleaning device 33 in the first embodiment is configured as shown in FIG. That is, the cleaning device 33 includes cleaning members 511 and 512 including two cleaning bias rollers arranged in a line between the exit guide plate 46 of the transfer conveyance belt device 23 and the entrance guide plate 48 of the fixing device 47. The photosensitive drum 24 is attached to the cleaning bias roller 511.
Bias applying means 521 comprising a cleaning bias power supply for applying a cleaning bias voltage having a polarity opposite to the above-mentioned toner charging polarity (the same polarity as the transfer bias);
The photosensitive drum 2 is attached to the cleaning bias roller 512.
And a cleaning blade 531 installed on a counter for removing toner from the cleaning bias rollers 511 and 512, respectively. , 532
And Cleaning bias rollers 511, 5
Reference numeral 12 is driven to rotate in a direction indicated by an arrow by a driving means.

Cleaning bias rollers 511 and 5
12 transfers the transfer paper 38 from the exit guide plate 46 to the entrance guide plate 48, and supplies a cleaning bias power supply 521,
Reference numeral 522 denotes the cleaning bias roller 51 at a timing slightly delayed from the transfer bias application timing from the high voltage power supply 34 to the bias roller 30 as shown in FIG.
A cleaning bias voltage is applied to 1,512. The absolute value of the bias voltage applied from the cleaning bias power supplies 521, 522 to the cleaning bias rollers 511, 512 is smaller than the transfer bias voltage from the high voltage power supply 34 to the bias roller 30, and the transfer paper 38 The two cleaning bias rollers 51 do not disturb the toner image formed on the surface.
The potential difference of 1,512 is set so as not to disturb the toner image formed on the transfer paper 38 during transfer.

The transfer paper 38 from the exit guide plate 46 passes over the cleaning bias roller 511, so that the positively charged toner adhered to the back surface is electrostatically cleaned by the cleaning bias roller 511.
By passing over the cleaning bias roller 512, the negatively charged toner attached to the back surface is electrostatically cleaned by the cleaning bias roller 512. That is, the positive polarity toner on the back surface of the transfer paper 38 is electrostatically cleaned by the cleaning bias roller 511, and the negative polarity toner on the rear surface of the transfer paper 38 is electrostatically cleaned by the cleaning bias roller 512. The toner adhered to the cleaning bias rollers 511 and 512 from the transfer paper 38 is cleaned by the cleaning blades 531 and 532, respectively, and collected by the collection screw 45 from the copying machine main body 22 into a waste toner collection container (not shown).

The cleaning bias power supply 521
Then, a cleaning bias voltage having the same polarity as the transfer bias is applied to the cleaning bias roller 511, and a cleaning bias voltage having a polarity opposite to the transfer bias is applied from the cleaning bias power supply 522 to the cleaning bias roller 512. A cleaning bias voltage having the opposite polarity to the transfer bias may be applied to the cleaning bias roller 511 from the cleaning bias power supply 522, and a cleaning bias voltage having the same polarity as the transfer bias may be applied to the cleaning bias roller 512 from the cleaning bias power supply 522. .

When the background toner on the photosensitive drum 24 is transferred to the transfer / transport belt 25 and cannot be cleaned by the cleaning device 32, the transfer bias is continuously applied to the toner attached to the transfer / transport belt 25. May be charged to the same polarity as the transfer bias.
In this embodiment, since the transfer bias is negative, the transfer conveyance belt 25 contains negatively charged oppositely charged toner. That is, the transfer conveyance belt 25 includes not only the positively charged toner but also the oppositely charged toner whose polarity is reversed.

The positively-charged toner and the reversely-charged toner on the transfer / transport belt 25 adhere to the back surface of the transfer paper 38. By applying the cleaning bias voltage and the cleaning bias voltage having the opposite polarity to the transfer bias, both the positively charged toner and the oppositely charged toner on the back surface of the transfer paper 38 are cleaned by the cleaning bias rollers 511 and 512.

As described above, in the second embodiment, cleaning bias voltages having different polarities are applied to the cleaning bias rollers 511 and 512 from the cleaning bias power supplies 521 and 522, and the cleaning bias rollers 511 and 512 apply the cleaning bias voltage. Since the back surface is cleaned, even if the positively charged toner and the oppositely charged toner adhere to the back surface of the transfer paper 38, these can be cleaned. In the second embodiment, two sets of cleaning bias power supplies 521 and 522, cleaning bias rollers 511 and 512, and a cleaning blade 53 are provided.
1, 532 are provided, but three or more pairs of cleaning bias power supplies, cleaning bias rollers, and cleaning blades are provided, and a cleaning bias voltage having the same polarity and reverse polarity as the transfer bias is applied from the cleaning bias power supply to the cleaning bias roller. Similar effects can be obtained by applying the voltage.

FIG. 12 shows a part of the third embodiment of the present invention. The third embodiment is an embodiment of the third aspect of the present invention. In the second embodiment, a bristle brush-like cleaning bias roller 513, 514 is used instead of the cleaning bias roller 511, 512. The cleaning roller 5 is used as a cleaning member for cleaning the cleaning bias rollers 513 and 514.
33, 534 and cleaning blades 531, 532
Is used. Cleaning rollers 533, 53
4 and the cleaning blades 531 and 532 are rotationally driven by drive means in the direction of the arrow shown in the figure.

Cleaning bias rollers 513 and 5
14 is a cleaning bias power supply 521,
A cleaning bias voltage having a different polarity is applied to the transfer paper 38 from the outlet guide plate 46 to the entrance guide plate 48 by cleaning the back surface of the transfer paper 38.
The positively charged toner and the reversely charged toner on the back surface are removed. The toner attached to the cleaning bias rollers 513 and 514 is cleaned by the cleaning rollers 533 and 534. Then, the cleaning rollers 533, 5
The toner on the cleaning blade 53
1,532
5, the toner is collected from the copying machine main body 22 into a waste toner collecting container (not shown).

In the third embodiment, since the bristle brush-like cleaning bias rollers 513 and 514 are used,
Even if the positively-charged toner and the reversely-charged toner adhere to the back surface of the transfer paper 38, they can be cleaned, and fine toner that cannot be removed by the cleaning bias rollers 511, 512 on the back surface of the transfer paper 38 is removed. Can be cleaned effectively. Further, the contact area between the bristle-shaped cleaning bias rollers 513 and 514 and the transfer paper 38 is reduced, and the adhesion of the floating toner deposited on the cleaning bias rollers 513 and 514 to the transfer paper 38 can be reduced.

The present invention is not limited to the above embodiment. For example, the cleaning bias roller 51 may be formed in a bristle brush shape in the first embodiment, and a facsimile machine other than a copying machine may be used. The present invention can be applied to a transfer conveyance device in an image forming apparatus such as a printer or a printer.

[0048]

As described above, according to the first aspect of the present invention, the transfer material is constituted by a dielectric having a resistance value including a medium resistance and is brought into contact with the image carrier to transfer the toner image on the image carrier. Transfer means for transferring the transfer material by transferring to the transfer means, a driving means for rotating the transfer means, a charge supply means for supplying charges to the transfer means, and a charge removing means for contacting the transfer means, In a transfer conveyance device in which a fixing device for fixing the toner on the transfer material is disposed on the downstream side in the transfer material conveyance direction, in the transfer material conveyance direction downstream from the transfer unit, and
Since a cleaning member is provided upstream of the fixing device in the transfer material transport direction to clean the back surface side of the transfer material, back contamination and background contamination of the transfer material transported to the fixing device can be prevented. The back stain of the material can be prevented.

According to the second aspect of the present invention, in the transfer / transport apparatus according to the first aspect, the cleaning member is provided with
And a bias applying means for applying biases having different polarities to the two or more cleaning members, so that even if the positively charged toner and the reversely charged toner adhere to the back surface of the transfer material, they are cleaned. can do.

According to the third aspect of the present invention, in the transfer / transport apparatus according to the first or second aspect, the cleaning member is formed in a bristle brush shape, so that fine toner on the back surface of the transfer material can be effectively cleaned. .

[Brief description of the drawings]

FIG. 1 is a sectional view showing a part of a first embodiment of the present invention.

FIG. 2 is a perspective view showing the first embodiment.

FIG. 3 is a schematic diagram illustrating a non-sheet passing state of the first embodiment.

FIG. 4 is a schematic diagram showing a paper passing state of the first embodiment.

FIG. 5 is a sectional view showing a part of the transfer conveyance belt of the first embodiment.

FIG. 6 is a plan view showing a part of the first embodiment.

FIG. 7 is a schematic view showing a conventional transfer and transport device.

FIG. 8 is a schematic view showing a part of the first embodiment.

FIG. 9 is a timing chart showing the operation timing of the first embodiment.

FIG. 10 is a sectional view showing a part of the second embodiment of the present invention.

FIG. 11 is a timing chart showing operation timings of the second embodiment.

FIG. 12 is a sectional view showing a part of a third embodiment of the present invention.

[Explanation of symbols]

Reference Signs List 21 transfer / conveyance device 23 transfer / conveyance belt device 24 photoconductor drum 25 transfer / conveyance belt 26 drive roller 27 driven roller 28 contact / separation lever 30 bias roller 31 contact plate 32, 33 cleaning device 34 high-voltage power supply 35 transfer control plate 47 fixing device 51, 511-514 Cleaning bias roller 52, 521, 522 Cleaning bias power supply 53, 531, 532 Cleaning blade 533, 534 Cleaning roller

──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Joji Mizuishi 1-3-6 Nakamagome, Ota-ku, Tokyo, Ricoh Co., Ltd. (72) Inventor Hoshi Ito 1-3-3 Nakamagome, Ota-ku, Tokyo No. 6, Ricoh Co., Ltd. (72) Inventor Tadashi Matsuda 1-3-6, Nakamagome, Ota-ku, Tokyo, Japan Ricoh Co., Ltd. (72) Yuko Harasawa 1-3, Nakamagome, Ota-ku, Tokyo No. 6, Ricoh Co., Ltd. (56) References JP-A-4-311986 (JP, A) JP-A-6-186865 (JP, A) JP-A-5-165342 (JP, A) Jpn. -107168 (JP, U) (58) Fields investigated (Int. Cl. ⁷ , DB name) G03G 15/16-15/16 103 G03G 21/10-21/12 G03G 15/20 G03G 15/00 510- 534

Claims (3)

(57) [Claims] A transfer means for transferring a toner image formed on a dielectric material having a resistance value including a medium resistance to a transfer material in contact with the image support and transferring the transfer material; A fixing device for fixing the toner on the transfer material, comprising: a driving unit that rotationally drives the transfer unit; a charge supply unit that supplies an electric charge to the transfer unit; and a charge removing unit that contacts the transfer unit. In the transfer conveyance device arranged downstream in the direction, in the transfer material conveyance direction downstream from the transfer means,
And a cleaning member disposed upstream of the fixing device in the transfer material transport direction to clean a back surface of the transfer material. 2. The transfer conveyance device according to claim 1, further comprising: two or more cleaning members; and bias applying means for applying biases having different polarities to the two or more cleaning members. Transfer device. 3. The transfer / transport apparatus according to claim 1, wherein said cleaning member has a bristle brush shape.