JP3312800B2 - Transfer belt device and transfer belt cleaning method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a transfer belt device in an image forming apparatus such as a copying machine, a printer, and a facsimile, and more particularly, to a transfer belt supported by a driving roller and a driven roller, and the transfer belt. And a charge removing means for removing charge from the transfer belt, and a cleaning device for cleaning the surface of the transfer belt, and transfer the toner image on the image carrier to the transfer material. The present invention relates to a transfer belt device for transferring and transferring a transfer material electrostatically.

Further, the present invention relates to a method for cleaning a transfer belt by the transfer belt device.

[0003]

2. Description of the Related Art In a conventional transfer belt apparatus of the type described above, a transfer bias is applied to a transfer bias roller attached to a transfer belt during a copy mode. As a result, a charge having a polarity opposite to the polarity of the toner on the photosensitive drum 1 is applied to the transfer belt having a predetermined resistance, and transfer is performed. The bias applied to the transfer belt for transferring the toner image on the image carrier onto the transfer material is usually of the same polarity as the image carrier and opposite to the toner. For this reason, at the time of direct contact between the image carrier and the transfer belt before and after the transfer material, the application of the electric field is stopped as much as possible to prevent the toner from adhering to the transfer belt. However, in spite of this, there occurs a problem that an abnormal image called back stain occurs on the transfer material as the first copy.

[0004]

When the cause of the occurrence of the above-mentioned abnormal image was investigated, the reversely charged toner in the toner was present on the transfer belt, and the reversely charged toner was transferred by the applied bias during the transfer of the transfer material. It was found that the toner adhered to the back side of the material and transferred to the transfer material, which is the first sheet of the copy, to cause back stain.

SUMMARY OF THE INVENTION It is an object of the present invention to eliminate the occurrence of back contamination of a transfer material by removing the oppositely charged toner.

[0006]

According to the present invention, there is provided a transfer belt apparatus of the type described in the industrial application field, wherein a cleaning blade is provided as a main cleaning mechanism of a cleaning apparatus, and an electric field is provided as a sub-cleaning mechanism. This problem can be solved by providing a cleaning member according to (1) and applying an electric field having a polarity opposite to the electric field applied to the charge applying means to the cleaning member by the electric field.

According to the present invention, there is provided a transfer belt apparatus having the above-described structure, wherein an electric field having a polarity opposite to an electric field applied to the charge applying means is applied to the cleaning member by the electric field, and the circumferential length of the transfer belt is adjusted. After the above-described application, the application is stopped, and then the copy mode is set to apply the electric field by the charge applying unit.When the copy mode ends, the application of the electric field by the charge application unit is stopped, and the application of the electric field to the cleaning member is performed again. The problem can be solved by a method in which the length is equal to or longer than the circumference of the transfer belt.

According to the present invention, in order to solve the above-mentioned problems, in the above-mentioned method, the application of the electric field to the cleaning member by the electric field during the copy mode is stopped. Simultaneously with the application of an electric field to the cleaning member, the electric field having the same polarity as the applied electric field of the charge applying means and a larger electric field is applied to the cleaning member,
After completion of the copy mode, the application of the electric field to the charge applying means and the application of the electric field to the cleaning member are stopped, and then the application of an electric field having a polarity opposite to that of the electric field applied to the charge applying means to the cleaning member by the electric field is performed. It is suggested to do more than the circumference.

Further, the present invention proposes, in the above-mentioned last proposal, that the transfer belt is neutralized by a neutralization member disposed at a position close to the front and rear of the cleaning member by the electric field.

[0010]

In the apparatus of the present invention, a cleaning device for cleaning the surface of the transfer belt is provided with a cleaning member for wiping residual toner adhered to the transfer belt and a cleaning member by an electric field. And an electric field having a polarity opposite to that of the electric field applied by the charge applying means for applying the electric charge to the transfer belt. Thereby, the oppositely charged toner present on the transfer belt is removed.

In the method of the present invention, in the transfer belt apparatus, an electric field having a polarity opposite to that of the electric field applied to the charge applying means is applied to the cleaning member by the electric field, and the cleaning is stopped after the application over the circumference of the transfer belt. Then, in a copy mode, an electric field is applied by the charge applying means,
At the end of the copy mode, the application of the electric field to the charge applying means is stopped, and the application of the electric field to the cleaning member is performed again over the circumference of the transfer belt. This allows
In addition to removing the oppositely charged toner present on the transfer belt, the influence on the transfer belt by the electric field cleaning method in the copy mode is eliminated.

In the above-mentioned method, the application of the electric field to the cleaning member by the electric field during the copy mode is stopped. An electric field of the same polarity and higher than that is applied to the cleaning member, and after the copy mode ends, the application of the electric field to the charge applying means and the application of the electric field to the cleaning member are stopped. As described above, by applying a strong electric field to the cleaning member during the copy mode, the margin of the transfer belt cleaning can be increased.

Further, by disposing a charge removing member at a position close to the front and back of the cleaning member to remove the charge from the transfer belt, the above-mentioned adverse effect due to the application of the strong electric field is prevented.

[0014]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described below with reference to the drawings.

In FIG. 1, a photosensitive drum 1 serving as an image carrier is rotatably provided, and on its outer periphery, although not shown, a static eliminator for removing the surface of the photosensitive drum 1, a photosensitive drum 1 Charging device that uniformly charges the surface of the photosensitive drum 1, an exposure device that scans a charged portion of the photosensitive drum 1 with an optical signal to form an electrostatic latent image, a developing device that develops the electrostatic latent image, and a photosensitive device after transfer. A process unit such as a cleaning device for cleaning the surface of the body drum 1 is disposed. A transfer belt 2 having a predetermined resistance is wound around a driving roller 3 and a driven roller 4 below the photosensitive drum 1.

The transfer paper fed to the registration roller pair 5 and being on standby is sent out from the registration roller pair 5 at the same time as the leading end of the toner image formed on the photosensitive drum 1 rotating in the direction of the arrow. When the leading end of the transfer paper comes close to the nip between the photosensitive drum 1 and the transfer belt 2, the transfer belt 2 is pushed up by the push-up lever 6 and contacts the photosensitive drum 1. When the transfer paper enters the nip portion, a transfer bias is applied to the transfer bias roller 7, and a charge having a polarity opposite to that of the toner on the photosensitive drum 1 is applied to the transfer belt 2, and the transfer is performed. Done. The charge applied to the transfer belt 2 and the transfer paper is removed by a contact plate 8 disposed on the downstream side in the traveling direction thereof.

The cleaning device 10 for cleaning the surface of the transfer belt is provided with a cleaning blade 11 made of polyurethane as a main cleaning mechanism for wiping off residual toner adhering to the transfer belt 2.
Further, a cleaning member 12 using an electric field is provided as a sub-cleaning mechanism. This cleaning member 12
, A bias roller method, a fur brush method, or the like can be used. Reference numeral 13 denotes a toner collecting coil.

In FIG. 2, a negative bias is applied to the photosensitive drum 1, and the toner on the surface thereof has a positive charge, but the toner is charged to the opposite polarity. Things exist. The oppositely charged toner is transferred to and held on the transfer belt 2 by pressure transfer. The transfer belt 2 has a substrate formed of rubber and a surface coated with a resin, and has poor smoothness. In addition, since the above-described oppositely charged toner has a small particle diameter, it is possible to clean the oppositely charged toner from the transfer belt. difficult. Therefore, the oppositely charged toner may remain on the transfer belt 2. The transfer paper 15 is conveyed to the remaining oppositely charged toner as described above, and a transfer bias (an electric field having the same polarity as that of the photosensitive drum 1) of a polarity opposite to that of the positively charged toner is applied by the transfer bias roller 7. Is pressed against and adheres to the back side of the transfer paper 15 and causes stains on the back side. 16 is a developing roller, and 17 is a peeling claw.

As shown in FIG. 3, in the present invention, a cleaning member 12 using an electric field is provided, and a bias having a polarity opposite to the bias applied to the transfer belt is applied to the cleaning member 12 to collect the oppositely charged toner from the transfer belt 2. In addition, the above-described back contamination of the transfer paper 15 is prevented.

An advantageous bias application timing to the cleaning member 12 will be described with reference to a flowchart shown in FIG.

(A) The transfer paper 15 is conveyed to the transfer belt 2 at the time t ₂ of the copy mode start, and comes into contact with the transfer belt 2.
This continues until the time t ₃ to the end of the copy mode.

(B) The transfer belt 2 is already driven and rotated at time t ₁ before the start of the copy mode.

(C) At time t ₂ , a negative electric field transfer bias is applied to the transfer bias roller 7 and ends at time t ₃ .

(D) A positive electric field bias is applied to the cleaning member 12 from the time t ₁ before the start of the copy mode to the time t ₂ . The bias application from time t ₁ to time t ₂ is applied over the entire circumference of the transfer belt 2, and this bias application is stopped during the copy mode. This eliminates the influence of the current generated by the cleaning member 12 during the copy mode on the transfer belt 2, and prevents the occurrence of abnormal images such as honeycombs and prints and the back contamination of the transfer paper 15.

The contact between the transfer belt 2 and the transfer paper 15 and the application of the transfer bias to the transfer bias roller 7 end at time t ₃ when the copy mode ends, and after this end, the bias application to the cleaning member 12. Is performed again over the entire circumference of the transfer belt 2.

In the embodiment shown in FIG. 5, the steps (a), (b), and (c) of FIG. 4 are the same, but the step (d) of applying a bias to the cleaning member 12 is as follows. It is performed by deformation.

(D ') After the bias is applied to the cleaning member 12 from the time t ₁ to the time t ₂ , the cleaning member 12 is in the copy mode from the time t ₂ to the time t _3.
Then, an electric field having the same polarity as the transfer bias applied to the transfer bias roller 7 and larger than the transfer bias is applied.

This is because, as described above, the transfer belt 2 is obtained by coating the surface of a substrate formed of rubber with a resin, so that the transfer belt 2 has poor smoothness, and there is a possibility that the coating layer may be cracked. This is because sufficient cleaning cannot be performed only by the cleaning blade, so that the margin of the cleaning performance is increased, the adhesion of the oppositely charged toner is prevented, and the back stain is eliminated.

In the embodiment shown in FIG. 6, before and after the transfer belt cleaning device 10 approaches the cleaning member 12 by the electric field, the static elimination members 18 and 19 are arranged. This eliminates the effect of the current generated by the cleaning member 12 during the copy mode on the transfer belt in the embodiment of applying the electric field to the cleaning member 12 described with reference to FIG.
Generation of abnormal images such as honeycombs and prints and transfer paper 15
This is for preventing back dirt.

[0030]

By removing the oppositely charged toner on the transfer belt, the back transfer of the first transfer paper is prevented.

By measuring the timing of applying an electric field to the cleaning member by the electric field, the influence on the transfer belt current during the copy mode is eliminated, and the occurrence of an abnormal image and the back contamination of the transfer paper are prevented.

In the copy mode, by applying to the cleaning member an electric field having the same polarity as the electric field applied by the charge applying means and a larger electric field, the toner on the concave and convex portions of the transfer belt is cleaned, and the cleaning margin is improved. Claim 3).

In the above-described case in which a strong electric field is applied to the cleaning member during the copy mode, the transfer belt static elimination member is disposed at a position close to the front and back of the cleaning member. To prevent occurrence of abnormal images such as honeycombs and prints, and to prevent back transfer of transfer paper.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram of a main part of a copying machine to which the present invention is applied.

FIG. 2 is an explanatory diagram of a state of a charged electric charge in a transfer section of the copying machine.

FIG. 3 is a diagram illustrating the function of a cleaning member using an electric field according to the present invention.

FIG. 4 is a flowchart of applying an electric field to a cleaning member in the copying machine.

FIG. 5 is a flowchart of another embodiment of applying an electric field to the cleaning member.

FIG. 6 is a view showing a modified embodiment of the present invention.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 photoconductor drum (image carrier) 2 transfer belt 3 drive roller 4 driven roller 7 transfer bias roller 10 cleaning device 11 cleaning blade 12 cleaning member by electric field 15 transfer paper 18, 19 static elimination member

──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Satoshi Takano 1-3-6 Nakamagome, Ota-ku, Tokyo Inside Ricoh Company, Ltd. (56) References JP-A-6-161288 (JP, A) JP-A Heisei 5-273824 (JP, A) JP-A-5-53401 (JP, A) JP-A-1-149079 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) G03G 15/16 G03G 21/10

Claims (4)

(57) [Claims] 1. A transfer belt supported by a driving roller and a driven roller, a charge applying unit for applying a charge to the transfer belt, a charge removing member for removing charge from the transfer belt, and cleaning a surface of the transfer belt. A transfer device for transferring a toner image on an image carrier onto a transfer material and electrostatically attracting and transferring the transfer material, wherein a cleaning blade is used as a main cleaning mechanism of the cleaning device. A transfer member provided with a cleaning member using an electric field as a sub-cleaning mechanism, and applying an electric field having a polarity opposite to the electric field applied by the charge applying means to the cleaning member using the electric field. 2. A transfer belt supported by a driving roller and a driven roller, a charge applying unit for applying a charge to the transfer belt, a charge removing member for removing charge from the transfer belt, and cleaning a surface of the transfer belt. A cleaning device as a main cleaning mechanism, and a cleaning member by an electric field as a sub-cleaning mechanism. The cleaning device transfers a toner image on an image carrier onto a transfer material and transfers the toner image onto the transfer material. In a transfer belt device that electrostatically attracts and conveys, an electric field having a polarity opposite to the applied electric field of the charge applying means is applied to the cleaning member by the electric field, and is stopped after the application over the circumference of the transfer belt, and then stopped. In the copy mode, an electric field is applied to the charge applying means. A method for cleaning a transfer belt, comprising: stopping application of an electric field to a step, and applying an electric field to the cleaning member again for a length equal to or greater than the circumference of the transfer belt. 3. A transfer belt supported by a driving roller and a driven roller, a charge applying unit for applying a charge to the transfer belt, a charge removing member for removing the charge from the transfer belt, and cleaning a surface of the transfer belt. A cleaning device as a main cleaning mechanism, and a cleaning member by an electric field as a sub-cleaning mechanism. The cleaning device transfers a toner image on an image carrier onto a transfer material and transfers the toner image onto the transfer material. In a transfer belt device that electrostatically attracts and conveys, an electric field having a polarity opposite to the electric field applied to the charge applying unit is applied to the cleaning member by the electric field over the circumference of the transfer belt or more, and then the copy mode is set. An electric field is applied to the charge applying means, and at the same time, has the same polarity as the applied electric field of the charge applying means and is larger than this. A threshold electric field is applied to the cleaning member, and after the copy mode ends, the application of the electric field to the charge applying means and the application of the electric field to the cleaning member are stopped. A method for cleaning a transfer belt, wherein a polarity electrolysis is applied to the transfer belt over its circumference. 4. The transfer belt cleaning method according to claim 3, wherein a charge of the transfer belt is removed by a charge removing member disposed in front of and behind the cleaning member by the electric field.