JP2001109351A - Image forming device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To effectively remove toner on a member to be cleaned and to realize satisfactory image quality. SOLUTION: In the image forming device provided with a cleaning device which has an electric cleaning means 70 collecting toner on an intermediate transfer object 5 being a member to be cleaned with electric force is installed and uses the electric cleaning means to which bias is applied to remove the toner from the intermediate transfer object 5, a conductive member 71 to which bias is applied is installed on the upper stream side of the rotary direction of the intermediate transfer object 5 than the electric cleaning means 70 is arranged.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a recording paper such as a copying machine, a printer, a facsimile or a multifunction machine thereof.
The present invention relates to various image forming apparatuses that record an image on a recording medium such as a card, and more particularly to an electrophotographic image forming apparatus that transfers an image formed on a transfer body such as a photoconductor and records the image on a recording medium. Things.

[0002]

2. Description of the Related Art In an electrophotographic image forming apparatus of this type, a toner image formed on a transfer member, for example, a photoreceptor, is temporarily transferred to another transfer member (hereinafter, referred to as an intermediate transfer member). There is also known an image forming apparatus in which the toner image transferred to the intermediate transfer body is secondarily transferred to a transfer material such as a recording sheet to form an image.

In an image forming apparatus having such a configuration, for example, in order to clean and remove the secondary transfer residual toner remaining on the intermediate transfer member after the secondary transfer from the intermediate transfer member, and to prepare for the next transfer, Various cleaning methods have been proposed and developed.

For example, as described in Japanese Patent Application Laid-Open No. 5-303310, the tip of an elastic blade is brought into contact with an intermediate transfer member as a member to be cleaned, and remains at the time of secondary transfer on the intermediate transfer member. A blade type that scrapes off toner (hereinafter referred to as secondary transfer residual toner), or a tip and end of a fur brush that contacts and slides on an intermediate transfer body,
A fur brush type, in which a bias having a polarity opposite to the charge polarity of the secondary transfer residual toner on the intermediate transfer body is applied, and the secondary transfer residual toner is removed from the intermediate transfer body by suction and suction by an electric force, is used. Are known.

Further, as described in JP-A-5-297739, in order to reduce the burden of the cleaning operation by the blade or the fur brush, the secondary transfer residue on the intermediate transfer body which cannot be removed by these blades or fur brushes. A method in which the toner is sucked and moved from the secondary transfer member to the photoconductor side and returned, and a method of removing the toner by a cleaning device on the photoconductor side,
As described in JP-A-1-105980, a cleaning device is not provided on the intermediate transfer member side, and the secondary transfer residual toner on the intermediate transfer member is opposite in polarity to the charging potential of the photosensitive member as a member to be cleaned. There is also known a system in which a charging device for charging the toner is provided, the secondary transfer residual toner is returned to the photoconductor by the charging device, and is removed by a cleaning device on the photoconductor side.

[0006]

However, in the mechanical cleaning method, there is a possibility that the cleaning blade is turned up or the tip of the blade is worn due to long-term use, resulting in poor cleaning. . On the other hand, any of the methods for recovering toner by using an electric force (hereinafter, referred to as an electric force) such as karaoke cannot sufficiently remove the toner and may cause a cleaning failure. Was.

That is, in the electric cleaning method, the secondary transfer residual toner of the intermediate transfer member is collected and removed by the cleaning device on the intermediate transfer member side. However, either one of the positive and negative bias is applied. It is difficult to collect and remove the secondary transfer residual toner charged to the same polarity as the polarity.

On the other hand, reverse transfer is performed to move the unrecovered secondary transfer residual toner to the primary transfer portion on the photosensitive member adjacent to the intermediate transfer member, and remove the toner by the cleaning device on the photosensitive member side. Even with such a configuration, the toner may not be able to move to the photosensitive member and may remain on the intermediate transfer member.

It is considered that the reason is that a discharge phenomenon occurs in a minute gap between the photosensitive member and the intermediate transfer member. Further, even if all the toner can be moved to the photoconductor, there is also a problem that the load on the cleaning device for the photoconductor increases because the amount of toner to be collected and removed increases.

Accordingly, a first object of the present invention is to provide an image forming apparatus capable of effectively collecting toner on a member to be cleaned and realizing good image quality. .

In addition, when the residual toner on the transfer body is collected and removed by the electric force of the electric cleaning means, the polarity of the charge applied to the residual toner itself varies.
If the same kind of charge as the bias polarity of the electric cleaning unit is applied, there is a possibility that the electric cleaning unit cannot sufficiently remove the residual toner.

Accordingly, a second object of the present invention is to increase the electric force when the residual toner on the member to be cleaned is sucked and removed by the electric cleaning means, and to reliably perform the cleaning action by the electric cleaning means. It is an object to provide an image forming apparatus having a simple structure and capable of removing residual toner at low cost.

[0013] Further, there is an increasing demand for downsizing of the image forming apparatus. However, there is a possibility that the housing of the image forming apparatus becomes larger by providing a conductive member in addition to the electric cleaning means.

Therefore, a third object of the present invention is to provide an image forming apparatus which is advantageous in reducing the size while improving the cleaning effect.

[0015] In addition, there is a case in which the residual toner cannot be sufficiently removed even by such a cleaning action. Therefore, it is desired to develop a device capable of obtaining a greater cleaning effect.

Accordingly, a fourth and fifth object of the present invention is to provide a conductive member with a mechanical cleaning function and a more effective mechanical cleaning function in addition to a function of applying a potential to a member to be cleaned. An object of the present invention is to provide an image forming apparatus that can be added.

Further, even when the electrostatic cleaning operation is performed by the electric cleaning means, for example, when the electric cleaning means is a brush, residual toner and the like firmly adhered to the side opposite to the end of the brush is removed. In some cases, it remains as it is.

Accordingly, a sixth and seventh object of the present invention is to provide an image forming apparatus capable of removing residual toner and the like which are not normally cleaned and adhered stubbornly at any time. .

[0019]

According to the first aspect of the present invention, in order to achieve the first object, there is provided an electric cleaning means for recovering the toner on the member to be cleaned by electric force, and a bias is applied to the electric cleaning means. In an image forming apparatus provided with a cleaning device for removing the toner from a member to be cleaned by an electric cleaning unit, a conductive member to which a bias is applied is provided upstream of the electric cleaning unit in a rotation direction of the member to be cleaned. Things.

According to a second aspect of the present invention, in order to achieve the second object, in the first aspect of the present invention, the bias applied to the electric cleaning means and the conductive member has opposite polarities.

According to a third aspect of the present invention, in order to achieve the third object, in the first or second aspect of the present invention, the conductive member is formed of a sheet.

According to a fourth aspect of the present invention, in order to achieve the fourth object, in the first aspect of the present invention,
A cleaning function is added to the conductive member.

According to a fifth aspect of the present invention, in order to achieve the fifth object, in the first aspect of the present invention, the electric cleaning means and the conductive member are rotated. The directions of the rotations are opposite to each other.

According to a sixth aspect of the present invention, in order to achieve the sixth object, in the first aspect of the present invention, the member to be cleaned is rotated reversely when image formation is not performed. It is configured to perform cleaning.

According to a seventh aspect of the present invention, in order to achieve the seventh object, in the invention according to any one of the first to sixth aspects, when image formation is not performed, when image formation is performed, The cleaning operation is performed by applying a polarity opposite to the polarity applied to the member to be cleaned to the member to be cleaned.

[0026]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, embodiments of the present invention will be described in detail with reference to the accompanying drawings.

FIG. 1 shows a color laser printer which is an image forming apparatus of the present invention. The color laser printer according to the first embodiment includes a photosensitive member 1, which is a member to be cleaned, a charging device 2, an exposure device 3, and a developing device 4.
, An intermediate transfer member 5 as a member to be cleaned, a sheet feeding device (not shown), a transfer device 6, a fixing device (not shown), and a cleaning device 7. Each device is unitized.

A photoreceptor belt is used for the photoreceptor 1 and is driven to rotate at a predetermined speed in a direction indicated by an arrow. A negatively charged organic photosensitive layer is formed on the surface of the photosensitive member 1 of this embodiment. Around the photoreceptor 1, a charging device 2, a developing device 4, and a first cleaning device 7A are provided.

The charging device 2 applies a high voltage to the photosensitive member 1 to give a uniform negative potential.

The exposure device 3 includes, for example, a laser (not shown), a polygon mirror, an f / θ lens, a reflection mirror, and the like. For example, from a laser,
A laser beam corresponding to each image of cyan (hereinafter abbreviated as C), magenta (hereinafter abbreviated as M), and yellow (hereinafter abbreviated as Y) is emitted. , An f / θ lens, and a reflection mirror, the light is incident on the photoreceptor 1 and optical writing is performed, and an electrostatic latent image of each color is formed.

The developing device 4 is provided with four developing cartridges each containing a toner of each color, which is charged with a predetermined charge. The developing cartridge is provided with a developing roller, and the toner of each color is electrostatically attracted to the electrostatic latent image via the developing roller to form a toner image.

The intermediate transfer member 5 uses an intermediate transfer belt. By applying a predetermined positive bias to the intermediate transfer member 5 of this embodiment, a toner image is transferred onto the intermediate transfer member 5, and this transfer operation is performed for each color, so that four toner images are superimposed. A four-color superimposed image is formed.

In the transfer device 6, a predetermined secondary transfer bias is applied to the recording paper P conveyed by a conveying means (not shown), so that the color toner of the four-color superimposed image formed on the intermediate transfer member 5 is transferred. The image is transferred onto the recording paper P.

The cleaning device 7 includes a first cleaning device 7A for removing the color toner remaining on the photoreceptor 1 and a second cleaning device 7B for removing the color toner remaining on the intermediate transfer member 5. ing. An elastic blade or the like is used for the first cleaning device 7A of this embodiment. On the other hand, in the second cleaning device 7B,
A conductive member 71 and an electric cleaning unit 70 are provided.

The fixing device is provided with a thermal transfer roller, and melts and fixes the color toner of each color carried on the recording paper P.

Next, the operation of the color laser printer according to this embodiment will be described. For example, a color image signal output from a computer (not shown) or the like is decomposed by the exposure device 3 into image signals of each color. The laser is operated according to the separated images of each color, and optical writing is performed for each color. That is, the laser beam is incident on the photoconductor 1, and an electrostatic latent image is formed for each color.

Next, the photosensitive member 1 on which the electrostatic latent image is formed
Reach the developing device 4, B, C, M, Y
Of the four developing cartridges respectively storing the four color toners, the developing cartridge corresponding to the color storing the color toner advances toward the photoconductor 1, and the developing roller provided in the developing cartridge Abuts or approaches the photoconductor 1.

As a result, each color toner stored in the developing cartridge and charged to the positive electrode is attracted from the developing roller toward the electrostatic latent image on the photosensitive member 1, and is attracted and attracted in accordance with the electrostatic latent image to form the toner image of each color. Is visualized as The color toner remaining on the photoconductor 1 (hereinafter, referred to as primary transfer residual toner) is removed by the first cleaning device 7A.

On the other hand, the color toner is sucked / adsorbed onto the intermediate transfer member 5 and transferred to the intermediate transfer member 5 when passing through a portion close to the primary transfer portion of the photosensitive member 1. Such a transfer operation is performed four times for each color, and the color toner images formed for each color are superimposed on the intermediate transfer belt to form a four-color superimposed image.

Next, the recording paper P fed one by one from the paper feeding device and conveyed toward the transfer device by the conveying means passes through the vicinity of the secondary transfer portion of the intermediate transfer body 5 when the recording paper P passes therethrough.
The color toner forming the four-color superimposed image formed thereon is attracted and transferred.

In this manner, the 4 transferred to the recording paper P
The color toner that forms the color superimposed image is then fused and fixed by a fixing device, and a color image is formed on the recording paper P.

On the other hand, in the intermediate transfer member 5 after the transfer of the color toner, the secondary transfer residual toner (color toner) remaining without the secondary transfer is removed by the second cleaning device 7B.

Next, the second cleaning device 7B according to the first embodiment of the present invention will be described in detail.

The second cleaning device 7B applies a predetermined potential to the secondary transfer residual toner in advance by utilizing the fact that the magnitude of the electric force acting on the charges in the electric field changes in proportion to the potential difference. A conductive member 71 provided to increase the toner density, and an electric cleaning unit 70 for adsorbing and collecting the secondary transfer residual toner with a strong electric force using the potential difference increased by the conductive member 71. , Casing 75
In preparation.

Among them, a cylindrical roller-shaped member made of a conductive material is used as the conductive member 71.
To this, a negative bias is applied and the intermediate transfer member 5 is in contact with the intermediate transfer member 5. In other words, the conductive member 71 has a polarity opposite to the polarity applied to the cleaning member 72 in order to more reliably perform suction removal by the electric force in the cleaning member 72 provided on the downstream side. Charge
The potential is increased in advance by applying the toner to the toner passing here.

Further, by applying a negative bias to the conductive member 71, the positively charged toner can also be recovered immediately after passing through the secondary transfer portion, which is difficult to recover by the cleaning member 72 described later. Is available.

On the other hand, the electric cleaning means 70 of this embodiment includes a cleaning member 72 having a brush, a bias roller 73, and a cleaning blade 74. A positive bias is applied to the bias roller 73, opposite to the conductive member 71, and a positive bias is applied to the cleaning member 72 that contacts the bias roller 73 via the bias roller 73. It has become.

In this embodiment, a cleaning member 72 having a brush is used as the electric cleaning means 70.
, Bias roller 73, cleaning blade 74
However, as shown in FIG. 2, for example, the bias roller 73 may be brought into direct contact with the intermediate transfer member 5 without providing the cleaning member 72 having a brush.

In these embodiments, the conductive member 7
1 and the cleaning member 72 are rotated in opposite directions. In this case, if the directions are opposite to each other, the conductive member 71 is rotated in directions opposite to the directions shown in FIGS. The cleaning member 72 may be rotated clockwise counterclockwise. Further, if both have the same cleaning effect, they may be rotated in the same direction.

Next, the operation of this embodiment will be described. The secondary transfer residual toner immediately after passing therethrough without being transferred at the secondary transfer portion of the intermediate transfer member 5 is mainly mainly positively charged. And there are those with zero charge.

Accordingly, of the second cleaning device 7B, the conductive member 71 to which a negative bias has been applied causes most of the secondary transfer residue having no positive charge or zero charge before passing therethrough. The toner can be negatively charged. It should be noted that some of the positively charged ones are just neutralized to zero charge by the application of the negative charges by the conductive member 71. On the other hand, what has been negatively charged from the beginning, the amount of negative charge is further increased, so that the cleaning member 72 can more strongly adsorb and collect it.

In the cleaning member 72 to which a positive bias is applied via the bias roller 73, the negatively charged secondary transfer residual toner having a large potential difference from the cleaning roller 72 is sucked and adsorbed and cannot be removed by electric force. Even for the secondary transfer residual toner having zero charge, the cleaning member 72
Mechanically scraped off by a brush.

Therefore, according to the first embodiment, in the cleaning section provided with the second cleaning device 7B, the secondary transfer residue in which positively and negatively charged ones and zero-charged ones are mixed. Although the toner is conveyed, the second cleaning device 7B can collect and remove mainly the negatively charged toner, the zeroly charged toner, and a part of the positively charged toner. it can.

Further, according to this embodiment, the toner not collected by the cleaning member 72 of the second cleaning device 7B (hereinafter, referred to as toner remaining after cleaning) is mainly charged positively. is there. Accordingly, the residual toner after cleaning is attracted and attracted to the negatively charged photoreceptor 1 side by electric force to perform reverse transfer, and can be removed by the first cleaning device 7A provided on the photoreceptor 1 side.

Further, for example, when the recording paper P stops during the conveyance due to a jam or the like, a large amount of the secondary transfer residual toner may be conveyed to the second cleaning device 7B. Even in such a case, the collection is insufficient with the second cleaning device 7B alone.
Even if the toner passes through the second cleaning device 7B, the toner remaining after cleaning is mainly charged positively by the cleaning member 72 when passing through the cleaning device 7B in the same manner as described above. Is reversely transferred to the photoreceptor 1 which is charged in the first direction, and can be removed by the first cleaning device 7A.

Next, a description will be given of a second cleaning device 7B according to a second embodiment of the present invention. The second shown in FIG.
The cleaning device 7B has the same configuration as in the first embodiment, but uses a sheet-shaped conductive material such as a synthetic resin (for example, PET) mixed with a conductive material, stainless steel, or aluminum as the conductive member 71. It is formed by forming it.

Therefore, according to the second embodiment, the occupied space is smaller than that of the conductive member formed in a roller shape, for example. Further, since the conductive member does not need to be forcibly driven to rotate, a drive transmission mechanism such as a motor or a gear can be used, compared to a roller or a brush formed for forcibly driving the rotation. Is unnecessary, so that further space saving and cost reduction can be achieved.

In this embodiment, only the conductive member 71 is formed in a sheet shape.
Only one may be formed in a sheet shape, or both may be formed in a sheet shape.

Next, a second cleaning device 7B according to a third embodiment of the present invention will be described. As the second cleaning device 7B according to this embodiment, the same cleaning device as that of the first embodiment or the second embodiment is used, but the surface of the sheet-like or roller-like conductive member 71 has a release property. A good coating is coated.

As the coating material, rubber, airlastomer, resin and the like can be mentioned. Specifically, as rubber, elastomer, natural rubber, isoprene rubber, styrene-butadiene rubber, butyl rubber, ethylene-propylene rubber, chloroprene rubber, chlorosulfonated polyethylene, chlorinated polyethylene, acrylonitrile butadiene rubber, urethane rubber, epichlorohydrin rubber, Thermoplastic elastomers such as acrylic rubber, silicone rubber, fluorine rubber, polysulfide rubber, polynorbornene rubber, hydrogenated nitrile rubber, polystyrene, polyolefin, polyvinyl chloride, polyurethane, polyamide, polyester, and fluororesin And the like.

The resins include polystyrene, chloropolystyrene, methyl methacrylate resin, butyl methacrylate resin, ethyl acrylate resin, butyl acrylate resin, modified acrylic resin, vinyl chloride resin, maleic acid resin, phenol resin, epoxy resin Resin, polyester resin, polyurethane resin, polyethylene, polypropylene, polybutadiene, polyvinylidene chloride, ionomer resin, silicone resin, fluorine resin, ketone resin, polyamide resin, polyphenylene oxide resin, and the like, but are not limited thereto. . These may be used alone or as a copolymer, alone or in combination of two or more.

Therefore, according to the third embodiment, since the surface releasability of the conductive member 71 is good, the secondary transfer residual toner sticks to the conductive member 71 and is fixed or not. It is possible to prevent such a problem that the toner adheres weakly to the surface of the conductive member 71 and drops on the surface of the intermediate transfer body 5 as a solid due to external factors such as vibration.

Next, a second cleaning device 7B according to a fourth embodiment of the present invention will be described. The second cleaning device 7B according to this embodiment is different from the first or second embodiment.
Although the same configuration as that of the embodiment may be used, a brush roller in which a conductive brush made of pile woven around a core material such as a conductive steel shaft or an aluminum pipe is spirally wound as the cleaning member 72 is used. The cleaning is performed by rotating and driving while contacting the intermediate transfer member 5.

As the fibers of the brush material, acrylic / carbon / nylon / carbon, polyester / carbon / polypropylene / carbon, etc. are used.

Therefore, according to this embodiment, the secondary transfer residual toner is electrically and mechanically collected by the rotating brush-like cleaning member 72. Like an elastic blade,
It is possible to prevent the occurrence of troubles, such as initial turning of the cleaning blade and wear due to long-term use, resulting in poor cleaning.

Next, a fifth embodiment of the present invention will be described. In this embodiment, the intermediate transfer body 5 is composed of a plurality of layers, and at least one of these layers is formed of an elastic body. In addition, any of the first and second embodiments can be used for the second cleaning device 7B.

The elastic body may be formed of an appropriate rubber material.

Therefore, according to this embodiment, various types of recording paper P have been used in recent years, but when these various types of recording paper are used, the transferability can be improved. it can. That is, by using a plurality of layers, for example, it is possible to prevent a problem on an image such as a blur and a void.

Further, since one layer of the intermediate transfer member 5 is formed of an elastic material, the contact pressure of the conductive member 71 in contact with the intermediate transfer member 5 can be reduced. While the pressing force by 71 can be reduced, the function of charging the secondary transfer residual toner can be sufficiently exhibited, so that the load on the intermediate transfer body 5 is reduced, and the life of both can be extended.

Next, a description will be given of a second cleaning device 7B according to a sixth embodiment of the present invention. In the second cleaning device 7B according to this embodiment shown in FIG.
The system is provided with electric cleaning means 70 ', 70 of the system. Among them, the same electric cleaning means 70 of the first embodiment shown in FIG.
In the system electric cleaning means 70 ', a conductive brush roller is used as the conductive member 71 in place of the conductive roller of the first embodiment, and a cleaning function is provided together with potential application to the secondary transfer residual toner. ing.

That is, in this embodiment, the first electrical cleaning means 70 ′ includes a conductive member 71 using a brush roll, a bias roller 76, and a cleaning blade 77. Among them, the conductive member 71 has the same structure as the second electric cleaning unit 70,
A bias is applied via the bias roller 76, and a negative bias having a polarity opposite to that of the bias roller 73 is applied to the bias.

The conductive member 71 and the cleaning member 72 are rotated in opposite directions. That is, the conductive member 71 is rotated in the opposite direction to the intermediate transfer belt 52, and the cleaning member 72 is rotated in the same direction as the intermediate transfer belt 52.

Therefore, according to this embodiment, since the conductive member 71 is rotated in the opposite direction to the intermediate transfer body 5,
Also in the case where the secondary transfer residual toner scatters, the secondary transfer residual toner scatters in the downstream direction of the intermediate transfer member 5, but the scattered secondary transfer residual toner rides on the intermediate transfer member 5 and moves toward the cleaning member 72. Head to. Then, the secondary transfer residual toner is cleaned again by the cleaning member 72. Since this cleaning member is rotating in the same direction as the intermediate transfer member 5, even if the secondary transfer residual toner scatters, the upstream transfer residual toner is removed. Side, the second cleaning device 7B
It is possible to prevent the secondary transfer residual toner from scattering to the downstream side, thereby causing an image defect.

Thus, even in a high-speed machine such as a color laser printer in which the intermediate transfer member 5, the conductive member 71, the cleaning member 72, etc. all rotate at a high speed,
It is possible to prevent the occurrence of cleaning failure due to scattering of the secondary transfer residual toner and adversely affecting the final image.

In this embodiment, a brush roll is used for the conductive member 71 and the cleaning member 72, but any of them may be a roller or a sheet.

For example, in the case of a roller, a material such as stainless steel or aluminum can be used. However, when a bias is directly applied to the roller, it is necessary to collect the toner. Must. In the case of this roller, a rod-shaped roller, a hollow roller, or the like can be used, and the surface thereof may be subjected to a treatment for improving the releasability or coated.
The conductive member 71 and the cleaning member 72
In this case, since a bias is applied to collect the toner, it is not preferable to use a material to which the toner easily adheres to the surface.

On the other hand, in the case of the brush-shaped material, for example, acrylic / carbon, nylon / carbon, polyester / carbon, polypropylene, carbon and the like can be used. In the case of this brush, a brush roller provided with a brush around a roller-shaped core material is used. As the brush roller, for example, a steel shaft or an aluminum pipe is used as a core material, and a pile-woven brush is spirally wound around the core shaft.

Next, a second cleaning device 7B according to a seventh embodiment of the present invention will be described. In the second cleaning device 7B according to this embodiment, when forming a full-color image, all the members shown in FIG. 4 are operated. on the other hand,
When forming a monochrome image, for example, the bias roller 75
Conductive member 71 including cleaning blade 76 and cleaning blade 76
Side first system cleaning means or bias roller 73
One of the second cleaning means on the cleaning member 72 side including the cleaning blade 74 is operated only on one side, and the other side is stopped. For this reason, the second cleaning device 7B is provided with a contact / separation mechanism that can be separated from the intermediate transfer body 5 on either side.

Therefore, according to this embodiment, the amount of the secondary transfer toner used when printing a monochrome image or the like is smaller than when printing a full-color image or the like. Therefore, the secondary transfer residual toner can be sufficiently collected only by the first or second cleaning means.

As a result, the life of the one-side cleaning means is extended and the life of the intermediate transfer member 5 is extended as compared with the structure in which both the first and second cleaning means are operated even when a monochrome image is formed. Can be stretched.

Next, a second cleaning device 7B according to an eighth embodiment of the present invention will be described. In the second cleaning device 7B according to this embodiment, at the end of the image forming operation, for example, when the predetermined operation time is exceeded, the intermediate transfer body 5 is rotated in the reverse direction to scrape the toner adhered to the conductive member 71. It is configured to drop. As means for scraping off the toner attached to the conductive member 71,
If a cleaning blade is used, it is too hard and not suitable. Therefore, it is desirable that the conductive member 71 and the cleaning member 72 mechanically scrape the cleaning blade. In this case, the image forming operation is stopped, and it is better to stop the application of the bias.

Next, a description will be given of a second cleaning device 7B according to a ninth embodiment of the present invention. In the second cleaning device 7B according to this embodiment, at the end of the image forming operation, for example, when a predetermined operating time is exceeded, the bias applied to the intermediate transfer body 5 is set to a polarity opposite to that of the image forming operation. It is configured to be. In this way, by applying the reverse polarity bias, the toner adhered to the conductive member 71 is once returned to the intermediate transfer member 5 and reversely transferred to the photosensitive member 1 side, and the toner is transferred to the photosensitive member 1 side. It is designed to be collected by one cleaning device 7A.

Next, three types of experiments, that is, first to third experiments for evaluating the cleaning performance of the first cleaning device 7A and the second cleaning device 7B provided in the image forming apparatus according to the present invention were performed. However, the result as shown in FIG. 5 was obtained. These experiments were performed in the following manner. 1st experiment: In this 1st experiment, what removed the conductive member 71 from the 2nd cleaning device 7B shown in FIG. 1 was used. The cleaning operation is performed by applying a positive bias to the cleaning member 72, and after the secondary transfer operation of the toner onto the recording paper is completed, the power is turned off. X area), a part immediately after passing through the cleaning unit (Y area), and a part immediately after passing through the vicinity of the primary transfer portion of the photoconductor 1 (Z
Area X), the three types of samples X in which the secondary transfer residual toner remaining on each area is adhered and transferred to a tape of a fixed size.
Y and Z were created. Second experiment: In the second experiment, the same one as in the first experiment in which the conductive member 71 was removed was used, but a negative bias was applied to the cleaning member 72. The cleaning operation is performed by the cleaning member 72, and then the first cleaning operation is performed.
In the same manner as in the experiment, three types of samples X, Y, and Z in which the secondary transfer residual toner remaining in each of the X, Y, and Z regions of the intermediate transfer member 5 was attached and transferred to a tape of a fixed size.
It was created. Third experiment: In the third experiment, a cleaning operation was performed using the second cleaning device 7B shown in FIG. 1 in which a positive bias was applied to the conductive member 71 and a negative bias was applied to the cleaning member 72. went. Thereafter, in the same manner as in the first and second experiments, the X, Y, Z
The three types of samples X, Y, and X are obtained by transferring the secondary transfer residual toner remaining in each of the regions to a tape of a fixed size.
Z was created.

Next, with respect to these samples obtained in the first experiment to the third experiment, B, C,
The density of each of the four colors M and Y was measured. The image density I of each color was calculated from the following equation, assuming that each density was I1 and the density of a blank tape of the same size as the previous tape was I2. I = I1−I2 Since it is considered that the image density I increases as the amount of the secondary transfer residual toner increases, the cleaning performance can be evaluated based on the density of the image density.

According to this evaluation experiment, as can be seen from FIG. 5, by providing the conductive member 71 in front of the cleaning member 72, for example, as can be seen from the result of the third experiment, the toner has already adhered from the X region. The amount has dropped significantly. That is, this is because the absolute amount of the secondary transfer residual toner is greatly reduced by the cleaning operation up to the previous time, and it has been found that the cleaning performance is dramatically improved.

In the Y area, since most of the secondary transfer residual toner is recovered, almost no secondary transfer residual toner is generated on the intermediate transfer member 5 after passing through the second cleaning device 7A. Therefore, it is possible to prevent a phenomenon that the secondary transfer residual toner is scattered thereafter.

[0087]

According to the first aspect of the present invention, a biased conductive member is provided upstream of the electric cleaning means in the rotation direction of the member to be cleaned, and the toner is charged by the conductive member. Because the potential difference between the electric cleaning means and the electric cleaning means is increased,
Since the electric force is increased by the characteristic of the electric force that the magnitude increases in proportion to the potential difference, the electric cleaning means effectively collects the residual toner on the member to be cleaned with the increased electric force. And good image quality can be obtained.

Further, according to the second aspect of the present invention, the bias applied to the electric cleaning means and the conductive member has opposite polarities, and the secondary transfer residual toner is previously reversed by the conductive member with respect to the electric cleaning means. And a large potential difference is applied to the electric cleaning means side, so that the electric force by the electric cleaning means when collecting the residual toner on the member to be cleaned increases. The cleaning function can be more reliably exhibited, and the residual toner can be removed at a low cost with a simple structure.

Further, by applying a potential of the opposite polarity by the conductive member, the toner immediately after the secondary transfer is charged to the same polarity as well as the toner charged to the opposite polarity to the electric cleaning means side. The conductive member can be charged to a polarity opposite to that of the electric cleaning means, so that the secondary transfer residual toner charged to both positive and negative polarities can be collected. And the cleaning effect is greatly improved.

Further, according to the third aspect of the present invention, since the conductive member is formed of a sheet, the occupied volume can be greatly reduced as compared with the roller.
Not only can a predetermined cleaning effect be exhibited, but it is also convenient for miniaturization. In addition, unlike the roller-shaped one, the sheet-shaped one does not need to be forcibly driven to rotate, and thus does not require a motor or the like.
In this respect, it is convenient for miniaturization, and furthermore, the manufacturing cost can be reduced.

Further, according to the fourth aspect of the present invention, the cleaning function is added to the conductive member, and after the potential is applied by the conductive member, the electric charge is canceled to zero and the recovery by the electric force is performed. Even toner that cannot be expected can be mechanically scraped and removed using a mechanical cleaning function, so that the cleaning effect is enhanced and the image quality of the formed image is also improved.

Further, according to the fifth aspect of the present invention, the electric cleaning means and the conductive member are configured to rotate in opposite directions to each other, so that the toner scattered when scraped by the conductive member is removed. Since the toner can be sent toward the electric cleaning means by the rotational force of the conductive member, it can be collected again by the electric cleaning means. Further, at the time of collection by the electric cleaning unit, the scattered toner can be transferred to the conductive member side by the electric cleaning unit which rotates in the reverse direction to the conductive member. It is also possible to collect, and it is possible to add a more effective mechanical cleaning function, and the cleaning effect is further enhanced.

According to the sixth aspect of the present invention, the cleaning is performed by rotating the member to be cleaned in the reverse direction when image formation is not performed. By this cleaning which can be performed, it is possible to remove the residual toner and the like which are firmly adhered to the electric cleaning means or the like.
As a result, it is possible to enhance the cleaning effect even in the usual cleaning after that,
It is possible to prevent troubles that remain as they are and later drop as a large lump, so that a high-quality cleaning device can be provided.

According to the seventh aspect of the invention, when the image is not formed, the polarity opposite to the polarity applied to the member to be cleaned when the image is formed is applied to the member to be cleaned. The cleaning operation is performed, and the same effect as the effect of the invention according to claim 6 can be obtained.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram of an example of an image forming apparatus.

FIG. 2 is a schematic configuration diagram illustrating a modified example of a second cleaning device provided in the image forming apparatus.

FIG. 3 is a schematic configuration diagram showing a second embodiment of the second cleaning device.

FIG. 4 is a schematic configuration diagram showing another embodiment of the second cleaning device.

FIG. 5 is a graph showing experimental results for confirming the evaluation of the cleaning effect of the cleaning device according to the present invention.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 photoconductor (cleaning member) 2 charging device 3 exposure device 4 developing device 5 intermediate transfer member (cleaning member) 6 transfer device 7 cleaning device 7A first cleaning device 7B second cleaning device 70 electric cleaning means 70 'electric cleaning Means 71 Conductive member 72 Cleaning member 73 Bias roller 74 Cleaning blade 75 Housing 76 Bias roller 77 Cleaning blade P Recording paper

 ──────────────────────────────────────────────────続 き Continued on the front page F-term (reference) 2H027 DA31 DA39 EA09 EA10 EA18 EB04 ED27 EG04 2H032 AA05 AA15 BA01 BA02 BA09 BA23 BA26 BA30 CA02 CA13 2H034 AA02 AA03 AA06 BA02 BA04 BA05 BC01 BC04 BC09 BD01 BD03 BD04

Claims (7)

[Claims] 1. An image forming apparatus comprising: an electric cleaning unit that recovers toner on a member to be cleaned by an electric force; and a cleaning device that removes the toner from the member to be cleaned by the electric cleaning unit to which a bias is applied. An image forming apparatus, wherein a bias-applied conductive member is provided upstream of the electric cleaning unit in the rotation direction of the member to be cleaned. 2. The image forming apparatus according to claim 1, wherein the bias applied to the electric cleaning unit and the bias applied to the conductive member have opposite polarities. 3. The image forming apparatus according to claim 1, wherein the conductive member is formed of a sheet. 4. The image forming apparatus according to claim 1, wherein a cleaning function is added to the conductive member. 5. The electric cleaning device according to claim 1, wherein the electric cleaning means and the conductive member rotate and the directions of the rotations are opposite to each other. The image forming apparatus as described in the above. 6. The image forming apparatus according to claim 1, wherein when the image is not formed, the member to be cleaned is rotated in the reverse direction to perform the cleaning. 7. The cleaning device according to claim 1, wherein a polarity opposite to a polarity applied to the member to be cleaned when the image is formed is applied to the member to be cleaned when the image is not formed. The image forming apparatus according to any one of claims 1 to 6, wherein: