JP6772933B2 - Cleaning device and image forming device equipped with it - Google Patents

Description

The present invention relates to a cleaning device for removing residual toner on the surface of an image carrier using a cleaning member, and an image forming device including the cleaning device.

Conventionally, an endless intermediate transfer belt that is rotated in a predetermined direction and a plurality of image forming portions provided along the intermediate transfer belt are provided, and each image forming portion puts a toner image of each color on the intermediate transfer belt. There is known an intermediate transfer type image forming apparatus that sequentially superimposes and transfers the primary transfer onto a recording medium.

In the intermediate transfer type image forming apparatus, when the intermediate transfer belt has an elastic layer, a cleaning brush that mechanically and electrically recovers the toner remaining on the surface of the intermediate transfer belt and a recovery roller that recovers the toner from the cleaning brush. A cleaning device equipped with a scraper that scrapes off the toner from the surface of the recovery roller and a transport spiral that transports the toner scraped off from the surface of the recovery roller to the waste toner recovery container is often used.

Some cleaning devices having the above configuration have a sealing member that partitions the inside of the housing into a cleaning brush side and a transport spiral side. The sealing member abuts the tip of the scraper on the upstream side of the scraper that scrapes off the toner from the surface of the recovery roller, thereby guiding the toner scraped off from the surface of the recovery roller by the scraper to the transport spiral side and cleaning brush. It is intended not to face the side (outside the housing). Therefore, the seal member needs to be in contact with the seal member at a substantially constant contact pressure so as not to scrape off the toner adhering to the recovery roller over the entire axial direction of the recovery roller.

By the way, toner may be deposited between the sealing member and the recovery roller. As a result, a gap is created between the recovery roller and the sealing member, and the toner on the transport spiral side flows back from the gap to the cleaning brush side. Then, when the backflowing toner reattaches to the cleaning brush and the toner reattached to the cleaning brush moves onto the intermediate transfer belt, so-called toner drops may occur and image defects may occur.

Therefore, in Patent Document 1, a seal member that comes into contact with the surface of a photoconductor and prevents toner from scattering from a developing device or a cleaning device is charged with the same polarity as the toner by triboelectric charging with the photoconductor. A method of preventing toner accumulation on the surface is disclosed. Further, Patent Document 2 discloses a method of preventing the back-charged transfer residual toner from adhering to the seal member by charging the seal member of the cleaning device with the same polarity as the transfer applied voltage.

Japanese Unexamined Patent Publication No. 3-194582 Japanese Unexamined Patent Publication No. 2004-61535

However, in the method of Patent Document 1, it is necessary to form the seal member with a material that is triboelectrically charged with the same polarity as the toner, and the material that can be used for the seal member is limited. Further, when the sealing member is charged with the same polarity as the toner, the accumulation of toner on the sealing member can be suppressed, but the toner electrically repelled by the sealing member may leak from the opening to the outside of the housing. On the other hand, when the seal member is charged with the same polarity as the transfer applied voltage as in Patent Document 2, toner that is not backcharged (opposite to the transfer applied voltage) is attracted to the seal member. Therefore, it was insufficient as a countermeasure against toner accumulation on the sealing member.

In view of the above problems, the present invention includes a cleaning device capable of effectively preventing the accumulation of scattered toner generated when the toner on the surface of the image carrier is removed on the sealing member using a cleaning brush, and a cleaning device thereof. It is an object of the present invention to provide an image forming apparatus.

In order to achieve the above object, the first configuration of the present invention is a cleaning device including a cleaning brush, a recovery roller, a scraper, a housing, and a sealing member. The cleaning brush removes the toner remaining on the image carrier by rotating in contact with the grounded image carrier. The recovery roller collects the toner adhering to the cleaning brush by rotating in contact with the cleaning brush. The scraper removes the toner adhering to the recovery roller. The housing is formed with an opening in which a part of the outer peripheral surface of the cleaning brush is exposed and a toner accommodating portion for storing toner removed from the recovery roller by a scraper. The sealing member is insulating and is arranged so as to come into contact with the recovery roller on the upstream side of the contact area with the cleaning brush in the rotation direction of the recovery roller, and divides the inside of the housing into an opening and a toner accommodating portion. .. By connecting the recovery roller to a voltage applying device, a voltage having the opposite polarity to that of the toner is applied. When the cleaning brush comes into contact with both the recovery roller and the image carrier, the cleaning brush is charged with a potential opposite to that of the toner and shifted to the same polarity side as the toner from the potential of the recovery roller. The sealing member is triboelectrically charged to a potential that is opposite in polarity to the toner and shifted to the same polarity side as the toner from the potential of the recovery roller due to friction with the recovery roller or the toner adhering to the recovery roller.

According to the first configuration of the present invention, the recovery roller has a larger electric adhesive force of the toner than the sealing member, so that the toner that has entered the contact portion between the sealing member and the recovery roller is carried around by the recovery roller. It is possible to smoothly slip through the contact portion. Therefore, since the accumulation of toner at the contact portion between the sealing member and the recovery roller is suppressed, it is possible to effectively suppress the occurrence of toner dropping due to the backflow of waste toner from the toner recovery portion to the opening. In addition, since the seal member is triboelectrically charged by friction with the recovery roller or the toner adhering to the recovery roller, there is no need for a power supply or wiring for applying a voltage to the seal member, and toner drop occurs easily and at low cost. It can be suppressed.

Schematic diagram showing the internal configuration of the image forming apparatus 100 on which the belt cleaning unit 19 of the present invention is mounted. Enlarged view of the vicinity of the image forming portion Pa in FIG. Side sectional view of the intermediate transfer unit 30 mounted on the image forming apparatus 100. External perspective view of the belt cleaning unit 19 according to the embodiment of the present invention. Side sectional view showing the internal configuration of the belt cleaning unit 19 of the present embodiment. The figure which shows typically the connection path between the belt cleaning unit 19 of this embodiment and a high voltage power source 70.

Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a schematic view showing the configuration of an image forming apparatus 100 on which the belt cleaning unit 19 of the present invention is mounted, and FIG. 2 is an enlarged view of the vicinity of the image forming portion Pa in FIG. Here, as the image forming apparatus 100, a so-called tandem color printer is illustrated.

In the main body of the image forming apparatus 100, four image forming portions Pa, Pb, Pc and Pd are arranged in order from the upstream side in the transport direction (right side in FIG. 1). Photoreceptor drums 1a, 1b, 1c and 1d carrying images of four different colors (cyan, magenta, yellow and black) are arranged in these image forming portions Pa to Pd, respectively, and charged, exposed, and charged, respectively. Cyan, magenta, yellow and black images are sequentially formed by each step of development and transfer. Further, in FIG. 1, an intermediate transfer belt 8 rotating in the clockwise direction is provided adjacent to the photoconductor drums 1a to 1d.

Next, the image forming units Pa to Pd will be described. Hereinafter, the image forming unit Pa will be described in detail, but since the image forming units Pb to Pd have basically the same configuration, the description thereof will be omitted. As shown in FIG. 2, a charging device 2a, a developing device 3a, and a cleaning device 7a are arranged around the photoconductor drum 1a along the drum rotation direction (counterclockwise direction in FIG. 2), and an intermediate transfer belt is provided. The primary transfer roller 6a is arranged with the 8 in between. Further, a belt cleaning unit 19 facing the tension roller 11 with the intermediate transfer belt 8 interposed therebetween is arranged on the upstream side of the photoconductor drum 1a in the rotation direction of the intermediate transfer belt 8.

Next, the image forming procedure in the image forming apparatus 100 will be described. When image data is input from a host device such as a personal computer, first, the surfaces of the photoconductor drums 1a to 1d are uniformly charged by the charging devices 2a to 2d. Next, the exposure apparatus 5 irradiates light according to the image data to form an electrostatic latent image corresponding to the image data on the photoconductor drums 1a to 1d. The developing devices 3a to 3d are filled with a predetermined amount of a two-component developer (hereinafter, also simply referred to as a developing agent) containing toners of each color of cyan, magenta, yellow, and black by the toner containers 4a to 4d. The toner in the developer is supplied onto the photoconductor drums 1a to 1d by 3a to 3d and adheres electrostatically. As a result, a toner image corresponding to the electrostatic latent image formed by the exposure from the exposure apparatus 5 is formed.

Then, an electric field is applied between the primary transfer rollers 6a to 6d and the photoconductor drums 1a to 1d by the primary transfer rollers 6a to 6d at a predetermined transfer voltage, and cyan, magenta, yellow, and cyan, magenta, yellow, and cyan, magenta, yellow, and cyanide, magenta, and yellow on the photoconductor drums 1a to 1d are applied. The black toner image is primarily transferred onto the intermediate transfer belt 8. The toner remaining on the surfaces of the photoconductor drums 1a to 1d is removed by the cleaning devices 7a to 7d.

The transfer paper P on which the toner image is transferred is housed in a paper cassette 16 arranged in the lower part of the image forming apparatus 100, and the transfer paper P is predetermined via the paper feed roller 12a and the resist roller pair 12b. At the timing, the paper is conveyed to the secondary transfer roller 9 provided adjacent to the intermediate transfer belt 8 and the nip portion (secondary transfer nip portion) of the intermediate transfer belt 8. The transfer paper P on which the toner image is secondarily transferred is conveyed to the fixing portion 13. Toner and the like remaining on the surface of the intermediate transfer belt 8 after the secondary transfer are removed by the belt cleaning unit 19.

The transfer paper P conveyed to the fixing portion 13 is heated and pressurized by the fixing roller pair 13a to fix the toner image on the surface of the transfer paper P, and a predetermined full-color image is formed. The transfer paper P on which the full-color image is formed is discharged to the discharge tray 17 as it is (or after being distributed to the reversal transport path 18 by the branch portion 14 and the images are formed on both sides) by the discharge roller pair 15.

FIG. 3 is a side sectional view of the intermediate transfer unit 30 mounted on the image forming apparatus 100. As shown in FIG. 3, the intermediate transfer unit 30 includes the intermediate transfer belt 8 spanned by the drive roller 10 on the downstream side and the tension roller 11 on the upstream side, and the photoconductor drums 1a to the intermediate transfer belt 8 via the intermediate transfer belt 8. It has primary transfer rollers 6a to 6d that come into contact with 1d. A belt cleaning unit 19 for removing toner remaining on the surface of the intermediate transfer belt 8 is arranged at a position facing the tension roller 11. The detailed configuration of the belt cleaning unit 19 will be described later.

The intermediate transfer unit 30 reciprocates a pair of support members (not shown) that rotatably support both ends of the rotation shafts of the primary transfer rollers 6a to 6d and the support members perpendicularly to the traveling direction of the intermediate transfer belt 8. A roller contact / detachment mechanism 60 having a driving means (not shown) for moving is provided. The roller contact / disengagement mechanism 60 has a color mode in which four primary transfer rollers 6a to 6d are pressed against the photoconductor drums 1a to 1d (see FIG. 1) via an intermediate transfer belt 8, and only the primary transfer rollers 6d. It is possible to switch between a monochrome mode in which the photoconductor drum 1d is pressed against the photoconductor drum 1d via the intermediate transfer belt 8 and a retracting mode in which all four primary transfer rollers 6a to 6d are separated from the intermediate transfer belt 8.

FIG. 4 is an external perspective view of the belt cleaning unit 19 according to the embodiment of the present invention, and FIG. 5 is a side sectional view showing an internal configuration of the belt cleaning unit 19. The belt cleaning unit 19 includes a fur brush 41, a recovery roller 43, a scraper 45, and a transfer spiral 47 in the housing 40, and one end of the housing 40 is cleaned by the fur brush 41, the recovery roller 43, and the transfer spiral 47. A drive input gear train 48 for inputting a driving force from a drive motor (not shown) is arranged.

The fur brush 41 is arranged on the opening 40a side of the housing 40 so as to face the tension roller 11 via the intermediate transfer belt 8. The fur brush 41 rotates in the counter direction (clockwise direction in FIG. 5) with respect to the moving direction of the intermediate transfer belt 8, so that foreign matter such as toner and paper dust remaining on the intermediate transfer belt 8 (hereinafter, toner, etc.) ) Is scraped off. The brush portion of the fur brush 41 in contact with the recovery roller 43 is made of conductive fibers having an electric resistance value of about 1 to 900 MΩ.

The recovery roller 43 collects the toner and the like adhering to the fur brush 41 by rotating in the direction opposite to the fur brush 41 (counterclockwise direction in FIG. 5) while contacting the surface of the fur brush 41. A high-voltage power supply 70 (see FIG. 6) is connected to the recovery roller 43, and a cleaning bias having a polarity opposite to that of the toner (here, negative electrode) is applied when cleaning the intermediate transfer belt 8. Further, the tension roller 11 is grounded to the ground. As a result, the toner or the like scraped from the intermediate transfer belt 8 is electrically and mechanically recovered by the brush portion of the fur brush 41, and further electrically transferred to the recovery roller 43.

The scraper 45 contacts the recovery roller 43 from the downstream side with respect to the rotation direction of the recovery roller 43 (counter direction with respect to the movement direction of the surface of the recovery roller 43), scrapes off the toner and the like collected by the recovery roller 43, and collects the toner. Clean the roller 43. The transport spiral 47 is arranged in the toner accommodating portion 40b of the housing 40, and transports the toner or the like scraped off from the recovery roller 43 by the scraper 45 to a waste toner recovery container (not shown) outside the housing 40. ..

Further, in the housing 40, the seal members 50 are arranged to face each other over the entire longitudinal direction of the recovery roller 43 (the direction perpendicular to the paper surface of FIG. 5). The seal member 50 is formed of an insulating film, and the tip end portion of the seal member 50 is in contact with the recovery roller 43 at a predetermined contact pressure. The inside of the housing 40 is divided into an opening 40a and a toner accommodating portion 40b by the sealing member 50. It is necessary to set the contact pressure of the seal member 50 so that the toner adhering to the recovery roller 43 is not scraped off and the toner or the like scraped off by the scraper 45 does not go toward the recovery roller 43 side again.

As described above, when toner is deposited on the contact portion between the seal member 50 and the recovery roller 43, a gap is formed between the seal member 50 and the recovery roller 43, and the opening 40a and the toner accommodating portion 40b are completely blocked. become unable. As a result, the waste toner that has flowed back from the toner accommodating portion 40b to the opening 40a may reattach to the fur brush 41 and further move onto the intermediate transfer belt 8 to cause toner drop.

Therefore, in the belt cleaning unit 19 of the present embodiment, the sealing member 50 is brought into contact with the recovery roller 43 or the toner adhering to the surface of the recovery roller 43 to be triboelectrically charged, so that the contact portion between the sealing member 50 and the recovery roller 43 is formed. It suppresses the accumulation of toner on the surface. More specifically, the seal member 50 is triboelectrically charged to the same polarity side as the toner as opposed to the toner and to the same polarity side as the toner.

In the belt cleaning unit 19 of the present embodiment, the material of the seal member 50 and the coating layer of the recovery roller 43 are arranged so that the charging series of the toner, the recovery roller 43, and the seal member 50 is in the order of toner> seal member 50> recovery roller 43. The material of the plating layer is selected.

For example, the sealing member 50 is formed using a polyester resin having a lower charging series than the toner, and a coating layer or a plating layer is used on the surface of the recovery roller 43 using a fluorine-based material having a lower charging series than the polyester resin. To form.

When two types of substances are rubbed against each other to be charged, the charging series refers to a substance in which a substance that is easily charged positively (+) is arranged at the top and a substance that is easily charged in the negative (-) at the bottom. The charging polarity of a substance changes depending on the friction partner, and when the upper substance and the lower substance of the charging series are rubbed together, the upper substance is positively charged and the lower substance is negatively charged. In the case of the present embodiment, the sealing member 50 is charged more positively than the recovery roller 43 and more negatively than the toner due to friction with the recovery roller 43 or the toner.

When the charge series of the seal member 50 and the toner are reversed and the charge series is in the order of seal member 50> toner> recovery roller 43, a flow of electric charge is generated from the toner to the seal member 50, and the charge amount of the toner is increased. It may decrease. As a result, the electrical adhesion of the toner to the recovery roller 43 is reduced, and the toner is likely to be deposited at the contact portion between the sealing member 50 and the recovery roller 43. On the contrary, when the charging series is in the order of toner> recovery roller 43> seal member 50, the sealing member 50 has a larger force to electrically attract the toner than the recovery roller 43, and the toner is more easily deposited. Therefore, in order to prevent the electric charge of the toner from being released while reducing the adhesive force of the toner to the sealing member 50, it is necessary to set the charging series in the order of toner> sealing member 50> recovery roller 43.

According to the configuration of the present embodiment, the recovery roller 43 has a larger electric adhesive force of toner than the seal member 50, so that the toner that has entered the contact portion between the seal member 50 and the recovery roller 43 is collected by the recovery roller 43. It is possible to smoothly slip through the contact part by turning around. Therefore, since the accumulation of toner at the contact portion between the sealing member 50 and the recovery roller 43 is suppressed, it is possible to effectively suppress the occurrence of toner dropping due to the backflow of waste toner from the toner recovery portion 40b to the opening 40a. Can be done.

Further, since the seal member 50 is triboelectrically charged by friction with the recovery roller 43 or the toner adhering to the recovery roller 43, there is no need for a power supply or wiring for applying a voltage to the seal member 50, and the occurrence of toner drop is simplified. Moreover, it can be suppressed at low cost.

Others The present invention is not limited to the above-described embodiment, and various modifications can be made without departing from the spirit of the present invention. For example, in the above embodiment, the belt cleaning unit 19 for removing the toner remaining on the surface of the intermediate transfer belt 8 by using the fur brush 41 is illustrated, but the surface of the photoconductor drums 1a to 1d is illustrated by using the fur brush 41. The same can be applied to cleaning devices 7a to 7d for removing the toner remaining in the above.

Further, in the above embodiment, the case of using the positively charged toner having a positive charging direction (plus side) has been described as an example, but the case of using a negatively charged toner having a negative charging direction (minus side) is also used. It is also applicable. When a negatively charged toner is used, the positive and negative directions of the material of the sealing member 50, the coating material of the recovery roller 43, and the plating material are completely opposite to those described above. That is, the seal member 50 may be formed of a material having a charge series higher than that of the toner so that the charge series is toner <seal member 50 <recovery roller 43, and the material has a charge series higher than that of the seal member 50. The recovery roller 43 may be coated or plated.

Further, the present invention is not limited to the tandem type color printer as shown in FIG. 1, and can be applied to various image forming devices equipped with a cleaning device such as a monochrome printer, a color copier, and a digital multifunction device.

The present invention can be used in a cleaning device that removes residual toner on the surface of an image carrier using a cleaning brush. By utilizing the present invention, it is possible to provide a cleaning device capable of effectively preventing leakage of scattered toner generated when removing toner on the surface of an image carrier using a cleaning brush to the outside of the housing.

Pa to Pd Image forming part 1a to 1d Photoreceptor drum 8 Intermediate transfer belt (image carrier)
9 Secondary transfer roller 19 Belt cleaning unit (cleaning device)
30 Intermediate transfer unit 40 Housing 40a Opening 40b Toner housing 41 Fur brush (cleaning brush)
43 Recovery roller 45 Scraper 47 Conveyance spiral 50 Sealing member 70 High-voltage power supply (voltage application device)
100 image forming device

Claims (5)

A cleaning brush that removes toner remaining on the image carrier by rotating in contact with the grounded image carrier.
A collection roller that collects toner adhering to the cleaning brush by rotating in contact with the cleaning brush.
A scraper that removes the toner adhering to the recovery roller, and
A housing in which an opening in which a part of the outer peripheral surface of the cleaning brush is exposed and a toner accommodating portion for storing toner removed from the recovery roller by the scraper are formed.
Wherein with respect to the rotation direction of the collection roller than the contact area of the cleaning brush is placed in contact with the recovery roller in the lower stream side, the insulating partitioning the inside said housing and said toner accommodating portion and said opening Seal member and
Have,
The recovery roller is connected to a voltage application device to apply a voltage having a polarity opposite to that of the toner, and the cleaning brush has a polarity opposite to that of the toner by contacting both the recovery roller and the image carrier. It is charged with a potential shifted to the same polarity side as the toner from the potential of the recovery roller.
The sealing member is triboelectrically charged to a potential that is opposite in polarity to the toner due to friction with the recovery roller or the toner adhering to the recovery roller and is shifted to the same polarity side as the toner from the potential of the recovery roller.
A cleaning device characterized in that the toner is positively charged and the charging series is lowered in the order of the toner, the sealing member, and the collecting roller. The cleaning device according to claim 1, wherein the sealing member is made of a polyester resin . The cleaning apparatus according to claim 1 or 2, wherein a coating layer or a plating layer made of a fluorine-based material is formed on the surface of the recovery roller . An image forming apparatus including the cleaning apparatus according to any one of claims 1 to 3 . An image forming part that forms a toner image and
An intermediate transfer belt on which the toner image formed in the image forming portion is primarily transferred, and
A secondary transfer roller that secondarily transfers the toner image that was primarily transferred on the intermediate transfer belt onto a recording medium, and
With
The image forming apparatus according to claim 4, wherein the cleaning apparatus is a belt cleaning apparatus that removes residual toner on the surface of the intermediate transfer belt .

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