Image formation device

An image formation device includes an image carrier that holds developed images, a transfer body that transfers the developed images held by the image carrier to a recording medium, a cleaning unit that cleans developer on the transfer body, a developer container in which the developer removed by the cleaning unit is deposited, and a sucking unit that sucks the developer leaking from the developer container, the transfer body having at least a rotating member of which both ends are rotatably supported, and the sucking unit having a suction hole opening at least at one end of the rotating member.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is based on and claims priority under 35 USC 119 from Japanese Patent Application No. 2009-282402 filed Dec. 14, 2009.

BACKGROUND

1. Technical Field

The present invention relates to an image formation device.

According to an aspect of the invention, there is provided an image formation device including an image carrier that hold developed images, a transfer body that transfers the developed images held by the image carrier to a recording medium, a cleaning unit that cleans developer on the transfer body, a developer container in which the developer removed by the cleaning unit is deposited, and a sucking unit that sucks the developer leaking from the developer container, the transfer body having at least a rotating member of which both ends are rotatably supported, and the sucking unit having a suction hole opening at least at one end of the rotating member.

DETAILED DESCRIPTION

Exemplary embodiments of the present invention will be described with reference to the accompanying drawings.

FIG. 1shows the overall configuration of an image formation device10pertaining to one exemplary embodiment of the invention. The image formation device10has an image formation device main body12, and a paper feed tray14is arranged in the lower part of this image formation device main body12. Further, an original copy reader (not shown) is arranged in the upper part of the image formation device main body12.

In the upper part of the image formation device main body12, multiple image formation units16are disposed, each corresponding to one of colors constituting color images. In this exemplary embodiment, image formation units16K,16Y,16M and16C respectively corresponding to black (K), yellow (Y), magenta (M) and cyan (C) are horizontally arrayed along an intermediate transfer belt18at regular intervals. The intermediate transfer belt18turns in the direction of arrow A in the drawing, and the four image formation units16K,16Y,16M and16C successively form toner images of the respective colors on the basis of image data inputted from an image processing device (not shown), and these multiple toner images are transferred to the intermediate transfer belt18(first transfer) at the timing of these toner images becoming superposed over another. Incidentally, the order of the image formation units16K,16Y,16M and16C is not limited to that of black (K), yellow (Y), magenta (M) and cyan (C), but may be in any other desired sequence.

Underneath the intermediate transfer belt18, a recording medium carriage path20is arranged. A recording medium22fed from the paper feed tray14is carried over this recording medium carriage path20, and the toner images of different colors are transferred onto the intermediate transfer belt18in a multiple state and transferred together onto the recording medium22(second transfer). The transferred toner images are fixed by a fixing device24, and the paper sheet bearing the images is ejected onto a paper ejection tray26.

Next, constituent elements of the image formation device10will be described in detail.

Since the image formation units16K,16Y,16M and16C are similarly configured except for the corresponding colors, the following description will refer only to the image formation unit16K as representative of all.

The image formation unit16K includes an image carrier32K, an electrifier34K that uniformly electrifies the surface of this image carrier32K, an exposing device36K that scans the image carrier32K with a laser beam to form an electrostatic latent image thereon, a developing device38K that develops the electrostatic latent image formed on the image carrier32K, a cleaning device40K and an antistatic device42K.

The image carrier32K is uniformly electrified by the electrifier34K, and a laser beam irradiated by the exposing device36K causes an electrostatic latent image to be formed thereon. The electrostatic latent image formed on the image carrier32K is developed by the developing device38K with a black (K) toner and is transferred to the intermediate transfer belt18(first transfer). After residual toner, paper powder and the like having stuck to the image carrier32K are removed by the cleaning device40K, the image carrier32K is cleared of electrostatic charge by the antistatic device42K.

The other image formation units16Y,16M and16C similarly form toner images of respectively yellow (Y), magenta (M) and cyan (C) in color, and transfer the toner images of these colors so formed to the intermediate transfer belt18(first transfer).

The intermediate transfer belt18is threaded round a driving roller52, a first idle roller54, a steering roller56, a second idle roller58, a backup idle roller60and a third idle roller62in a fixed tension. The rotational driving of the driving roller52by a driving motor (not shown) drives the intermediate transfer belt18in a circulatory motion at a prescribed speed.

The intermediate transfer belt18is made by forming a flexible film of polyimide or some other synthetic resin in a belt shape and connecting the synthetic resin film belt so formed by welding or otherwise into an endless belt.

In the positions respectively opposing the image formation units16K,16Y,16M and16C within the intermediate transfer belt18, first transfer rollers66K,66Y,66M and66C are disposed, and the toner images of the respectively corresponding colors formed on the image carriers32K,32Y,32M and32C are transferred in a multiple state onto the intermediate transfer belt18by the first transfer rollers66K,66Y,66M and66C. Any residual toner stuck to the intermediate transfer belt18is removed by a cleaning device68disposed downstream of the second transferring position.

On the recording medium carriage path20, a paper feed roller72that takes the recording medium22out of the paper feed tray14, a first carrying roller pair74, a second carrying roller pair76, a third carrying roller pair78and a registration roller80that carries the recording medium22at a prescribed timing to the second transferring position are arranged.

A second transfer belt90is disposed in the second transferring position on the recording medium carriage path20. The second transfer belt90is supported by a second transfer roller92and a driven roller93. The second transfer belt90is driven in a circulatory motion at a prescribed speed by the rotational driving of the second transfer roller92by a driving roller (not shown).

The second transfer roller92is arranged in pressure contact with the backup idle roller60with the second transfer belt90in-between, and this pressure contact force of the second transfer roller92and an electrostatic force cause the toner images in different colors transferred in a multiple state onto the intermediate transfer belt18to be transferred onto the recording medium carried over the second transfer belt90(second transfer). The recording medium22onto which the toner images in different colors have been transferred (second transfer) is carried from the second transfer belt90to a first conveyor belt94aand then to the fixing device24by a second conveyor belt94band a third conveyor belt94c. The fixing device24subjects the recording medium22, onto which the toner images in different colors have been transferred (second transfer), to heating and pressuring to melt the toners and fix them to the recording medium22.

The second transfer belt90is provided with a second transfer cleaning device100that removes residual toners having stuck to this second transfer belt90. A sucking device102is further disposed in the vicinities of the second transfer cleaning device100and below the first conveyor belt94a.

Next, the first to third conveyor belts94a,94band94cwill be described in detail. Incidentally, since the first to third conveyor belts94a,94band94care similarly configured, they will be referred to collectively as the conveyor belts94in the following description.

FIG. 2shows a perspective view of a conveyor belt94. The conveyor belt94has a belt main body104, and this belt main body104is supported by a driving roller106aand a driven roller106b. Following the driving by the driving roller106a, the belt main body104rotates.

The belt main body104has an air suction hole108, and an air suction unit110and an air suction duct112are disposed inside the belt main body104.

The air suction unit110is, for instance, a DC fan, and discharging of air within the air suction duct112by this air suction unit110brings down the air pressure within this air suction duct112. When the air pressure within the air suction duct112falls, air is sucked through the air suction hole108to cause the belt main body104to adsorb the recording medium22.

In this way, the first to third conveyor belts94a,94band94cadsorb and carry the recording medium22.

Next, the configuration in the second transferring position will be described in detail.

FIG. 3shows a cross section of the second transfer cleaning device100and the structure surrounding the same. The second transfer cleaning device100has a collection box120as a developer container in which residual toners on the second transfer belt90are to be deposited. In the collection box120, a scraper121for scraping off the residual toners on the surface of the second transfer belt90is arranged, and cleaning rollers122aand122barranged in contact with the second transfer belt90are rotatably supported.

A voltage of the polarity reverse to the polarity of the electrification of the residual toners on the second transfer belt90is applied to the cleaning rollers122aand122b. The configuration is that an electric field in which the residual toners electrostatically shift from the surface of the second transfer belt90toward the cleaning rollers122aand122bis generated in this way to remove the residual toners on the second transfer belt90. Also, discharge products, paper powder and the like having stuck to the second transfer belt90are removed by the cleaning rollers122aand122b.

Each of the cleaning rollers122aand122bis configured by forming an elastic layer of a prescribed thickness around a shaft of a prescribed diameter and covering the resultant thermal insulation layer with a textile layer.

The shaft is formed of a metal such as iron or SUS. The elastic layer is formed of, for instance, spongy urethane foam adjusted to a prescribed resistance level by blending electric conductors such as carbon black. Incidentally, the material of the elastic layer is not limited to urethane foam but can as well be appropriately selected out of rubbers such as NBR, SBR and EPDM.

The textile layer is formed of a material formed into a cloth form by knitting electroconductive fibers, a material formed into a cloth form by weaving electroconductive fibers, unwoven cloth formed of electroconductive fibers or the like. The electroconductive fibers may be, for instance, split nylon electroconductive fibers in which carbon black is dispersed. The use of very fine electroconductive fibers serves to increase the surface area of the textile layer, thereby enabling a large quantity of toners to be held and the cleaning performance to be enhanced.

The types of unwoven cloth usable for this purpose include dry unwoven cloth, sponge bands and wet unwoven cloth. Dry unwoven cloth, specifically, is made by forming fibers of a few centimeters in length into thin sheets by carding with an air random machine and stacking a few such sheets as required. Joining of fibers is achieved by entangling them with a pressured fine stream of water.

The cleaning rollers122aand122bare reduced in sliding friction with the surface of the second transfer belt90by arranging on the surface of the textile layer made up of soft electroconductive fibers and forming the elastic layer underneath the textile layer.

The cleaning rollers122aand122bhave collection rollers124aand124b, arranged in contact with them, for collecting the residual toners removed by these cleaning rollers122aand122b.

To the collection rollers124aand124b, voltages to generate electric fields that shift the residual toners on the surfaces of the cleaning rollers122aand122btoward these collection rollers124aand124bare respectively applied.

The collection rollers124aand124bare rollers of a prescribed external diameter, formed of phenol resin whose resistance level is adjusted by dispersing carbon black. Or they may be made of a metal such as aluminum alloy or stainless steel alloy on whose surface a film of fluorine resin or the like is formed. This serves to smoothen sliding on scrapers126aand126bto be described afterwards. The configuration of the collection rollers124aand124bis not limited to what is described above, but can be selected as appropriate with the system used.

Also, the scrapers126aand126bthat scrape off the residual toners having stuck to the surfaces of these collection rollers124aand124bare arranged beside the collection rollers124aand124b.

Each of the scrapers126a,126band121is composed of a plate-shaped member formed of a metal such as iron or stainless steel alloy.

In this way, the toners on the second transfer belt90are cleaned by the scrapers121,126aand126b, the cleaning rollers122aand122b, and the collection rollers124aand124b, and the removed toners are deposited in the collection box120.

Upstream the second transfer belt90in the carrying direction of the recording medium22, an upstream side connecting part128that connects the registration roller80and the second transfer belt90is arranged, and downstream the same in the carrying direction of the recording medium22, a downstream side connecting part130that connects the second transfer belt90and the first conveyor belt94ais arranged.

The sucking device102arranged below the first conveyor belt94sucks floating matters in the air. The floating matters include toners leaking (scattered) from the second transfer cleaning device100and floating (toner cloud) and paper powder. In the following description, toner cloud will be referred to as representative of such floating matters.

Next, the configuration of the sucking device102will be described in detail.

FIG. 4shows a sectional view of the sucking device102. The sucking device102includes a sucking device main body140, a sucking part142that takes toner cloud into this sucking device main body140, a filter144of a corrugated shape, for instance, that catches the toner cloud (toners) taken in from the sucking part142and a blower146that generates a sucking air flow.

The sucking part142is provided with multiple (two in this exemplary embodiment) suction inlets148through which toner cloud is taken in, and a guiding part150that guides the toner cloud taken in through these suction inlets148to the filter144.

The blower146is provided with an air intake146athrough which air having passed the filter144is taken in and an exhaust outlet146bthat discharges air taken in through this air intake146a. The air intake146ais disposed on the side opposite the filter144(the upper part inFIG. 4), and the exhaust outlet146bis disposed orthogonally to the direction of the air flow from the filter144to the air intake146a(in the horizontal direction inFIG. 4).

Therefore, toner cloud, guided by the sucking air flow generated by the blower146, is taken into the sucking device main body140from the suction inlets148, passes the guiding part150and is caught by the filter144. The air having passed the filter144is sucked through the air intake146aof the blower146and, with its traveling direction changed, is discharged through the exhaust outlet146binto the image formation device main body12(sucked in the perpendicular direction and discharged in the horizontal direction inFIG. 4). By causing the filter144to catch the toner cloud and discharging it into the image formation device main body12, an exhaust unit to discharge it out of the image formation device main body12is made unnecessary.

Next, the arrangement of the sucking device102will be described in detail.

FIG. 5shows a top view of the second transfer belt90, the sucking device102and the structure surrounding the same, whileFIG. 6shows a cross-sectional perspective view of the second transfer belt90, the sucking device102and the structure surrounding the same.

The second transfer roller92and the driven roller93that support the second transfer belt90are disposed in supports12awhich constitute parts of the image formation device main body12. Since the second transfer belt90rotates here, gaps G are formed between this second transfer belt90and the supports12a. For this reason, toner cloud arising from the second transfer cleaning device100arranged underneath the second transfer belt90(attributable to, for instance, the toners collected into the collection box120or the toners scraped off by the scrapers126aand126b) escapes through these gaps G out of the second transfer cleaning device100more easily than elsewhere. As a result, toners accumulate in the downstream side connecting part130near the gaps G. If the recording medium22is carried in this state, the recording medium22will be contaminated.

The suction inlets148of the sucking device102are so arranged as to cause toner cloud to be sucked from below the first conveyor belt94atoward the gaps G. Thus, toner cloud having escaped through the gaps G passes between the second transfer belt90(the downstream side connecting part130) and the first conveyor belt94aand is sucked by the sucking device102.

For this reason, compared with a case in which the suction inlets148are not arranged near the gaps G, toner cloud arising from the second transfer cleaning device100is more effectively sucked by the sucking device102. Therefore, compared with a case in which this configuration is absent, it is more difficult for toner cloud to accumulate in constituent elements of the image formation device main body12near the gaps G such as the downstream side connecting part130, and contamination of the recording medium22is thereby prevented.

Further, the configuration is such that the sucking device102is arranged below the first conveyor belt94aand toner cloud is sucked in the same direction as the direction in which this first conveyor belt94a(as well as the second conveyor belt94bor the third conveyor belt94c) sucks the recording medium22(downward inFIG. 3). Therefore, even when the recording medium22is being carried, the sucking device102sucks toner cloud without obstructing the carriage of the recording medium22.

To add, though the foregoing exemplary embodiment is described with respect to the configuration in which the sucking device102discharges the air having passed the filter144into the image formation device main body12, this is not the only conceivable configuration, but a discharge unit for discharging the exhaust out of the image formation device main body12may as well be provided to be caused to discharge the exhaust out of the image formation device main body12.

Next, a second exemplary embodiment of the invention will be described.

FIG. 7shows a top view of the second transfer belt90, the sucking device102and a structure surrounding the same in the second exemplary embodiment of the invention.

On each of the supports12a, a supporting face12bwhich is a face that opposes the image formation device main body12and on which the second transfer roller92and the driven roller93are disposed is formed. The supporting faces12bconstitute parts of the boundaries forming the gaps G.

An area A represents the width of the recording medium22passing the second transfer belt90. The area A is, for instance, a range in which the recording medium22of the maximum width for use in the image formation device10passes.

An area B represents the maximum width of image formation.

In the second exemplary mode, the outer edges148aof the suction inlets148are arranged, with respect to the axial direction of the second transfer belt90(hereinafter sometimes referred to as simply the “axial direction”), farther outside than the area A and farther inside than the supporting face12b.

On the other hand, the inner edges148bof the suction inlets148are arranged, with respect to the axial direction, farther inside than the area A. The edges148bmay as well be arranged, with respect to the axial direction, farther outside than the area A.

Thus, in this exemplary mode of implementation, the suction inlets148are arranged, with respect to the axial direction of the second transfer belt90, outside the range in which the recording medium22passes and a range farther inside than the supporting face12bthat overlapping occurs at least partly.

No toner is transferred to the recording medium anywhere farther outside than the area A, and toner cloud is more likely to be generated than in any other part of the second transfer belt90. For this reason, by arranging the suction inlets148as in this configuration, toner cloud can be more efficiently sucked than the case in which this configuration is absent.

Next, a third exemplary embodiment of the invention will be described.

FIG. 8shows a top view of the second transfer belt90, the sucking device102and a structure surrounding the same in the third exemplary embodiment of the invention.

In the third exemplary mode, the outer edges148aof the suction inlets148are arranged, with respect to the axial direction, farther outside than the supporting face12b.

On the other hand, the inner edges148bof the suction inlets148are arranged, with respect to the axial direction, farther outside than the area A.

Thus in this exemplary mode of implementation, the configuration is such that one end148aof each of the suction inlets148is arranged, with respect to the axial direction of the second transfer belt90, farther outside than the supporting face12b, and the other end148bis farther inside than the supporting face12band farther outside than the area A.

To add, the end faces148bmay as well be arranged, with respect to the axial direction, farther inside than the area A.