Cleaning device, image forming apparatus, and cleaning method

A cleaning device includes a cleaning member that cleans a surface of an image carrier by removing developer from the surface of the image carrier, the developer remaining on the surface of the image carrier instead of being transferred onto a transfer body; a housing that receives the developer removed by the cleaning member; a transporting member provided in the housing, the transporting member transporting the developer toward an end of the image carrier in a rotational axis direction; a first sealing member that fills a gap between the image carrier and the housing at an upstream side in a transporting direction of the developer; and a second sealing member that fills a gap between the image carrier and the housing at a downstream side in the transporting direction of the developer, the second sealing member having a denser structure than the structure of the first sealing member.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is based on and claims priority under 35 USC 119 from Japanese Patent Application No. 2010-198363 filed Sep. 3, 2010.

BACKGROUND

The present invention relates to a cleaning device, an image forming apparatus, and a cleaning method.

SUMMARY

According to an aspect of the invention, there is provided a cleaning device including a cleaning member that cleans a surface of a rotating image carrier by removing developer from the surface of the image carrier, the developer remaining on the surface of the image carrier instead of being transferred onto a transfer body; a housing that receives the developer removed by the cleaning member; a transporting member provided in the housing, the transporting member transporting the developer toward an end of the image carrier in a rotational axis direction; a first sealing member that fills a gap between the image carrier and the housing at an upstream side in a transporting direction of the developer; and a second sealing member that fills a gap between the image carrier and the housing at a downstream side in the transporting direction of the developer, the second sealing member having a denser structure than the structure of the first sealing member.

DETAILED DESCRIPTION

An exemplary embodiment of the present invention will be described with reference to the accompanying drawings. InFIG. 1, the arrow “UP” indicates the upper side of an image forming apparatus10, and the arrow “RI” indicates the right side of the image forming apparatus10. In addition, the side visible inFIG. 1is defined as the front side of the image forming apparatus10. In the present exemplary embodiment, a recording sheet P is described as an example of a transfer body. An upstream side and a downstream side in a transporting direction of the recording sheet P is sometimes referred to simply as “upstream side” and “downstream side”, respectively.

Referring toFIG. 1, image forming units20Y,20M,20C, and20K, which are an example of image forming members, are arranged in the vertical direction in a housing11of the image forming apparatus10. The image forming units20Y to20K form images with toners (developers) of respective colors, which are yellow (Y), magenta (M), cyan (C), and black (K), respectively. The image forming units20Y,20M,20C, and20K are arranged in that order from the lower side of the image forming apparatus10(upstream side of a sheet transport path15) toward the upper side of the image forming apparatus10(downstream side of the sheet transport path15).

The image forming units20Y to20K have similar structures except that different types of toners are stored in developing units24, which will be described below. In the following description, the letters ‘Y’, ‘M’, ‘C’, and ‘K’ are attached to reference numerals denoting components corresponding to yellow (Y), magenta (M), cyan (C), and black (K) when they are to be distinguished from each other. The letters ‘Y’, ‘M’, ‘C’, and ‘K’ are omitted when it is not necessary to distinguish the components corresponding to the respective colors. The manufacturing methods of the toners of ‘Y’, ‘M’, ‘C’, and ‘K’ are not particularly limited.

Referring toFIG. 1, a sheet feeding unit12in which recording sheets P are stored is disposed at a lower section of the housing11. A sending-out roller14that sends out the recording sheets P is disposed above the sheet feeding unit12. Transporting rollers16, which are a pair of rollers that transport a recording sheet P, and positioning rollers18, which are a pair of rollers that adjust the time at which the recording sheet P that has been transported by the transporting rollers16is further transported, are disposed downstream of the sending-out roller14. The sheet transport path15includes the transporting rollers16and the positioning rollers18.

A transporting unit40is disposed in the right section of the housing11inFIG. 1(at the position where the transporting unit40is opposed to photoconductors26(described below), which are an example of image carriers). The transporting unit40is disposed adjacent to the image forming units20Y to20K and transports the recording sheet P successively to the image forming units20Y to20K.

The transporting unit40includes a drive roller42, a driven roller44, and a transporting belt46. The drive roller42and the driven roller44are arranged vertically along a side wall (right side wall inFIG. 1) of the housing11. The transporting belt46is stretched around the drive roller42and the driven roller44, and is rotated when the drive roller42is rotated by a motor (not shown). Although not illustrated, an absorption roller that causes the recording sheet P to be electrostatically attracted to the transporting belt46when a voltage is applied to the absorption roller is opposed to the driven roller44with the transporting belt46interposed therebetween.

Transfer rollers48are disposed inside the transporting belt46such that the transfer rollers48are opposed to the photoconductors26of the respective colors. A voltage is applied to the transfer rollers48by a voltage applying unit (not shown) so that toner images formed on the photoconductors26are transferred onto the recording sheet P while the recording sheet P is being transported by the transporting belt46. A fixing unit50is disposed downstream of the transporting unit40and above the image forming unit20K. The fixing unit50is an example of a fixing member that fixes the toner images that have been transferred onto the recording sheet P to the recording sheet P.

The fixing unit50includes a heating roller52that heats and melts the toner included in the toner images that have been transferred onto the recording sheet P, a pressing roller54that is in contact with the outer peripheral surface of the heating roller52and presses the outer peripheral surface of the heating roller52, and a cover member56that covers the heating roller52and the pressing roller54.

The heating roller52includes, for example, a cylindrical core bar (not shown) made of aluminum and coated with silicone rubber and fluorocarbon resin and a halogen heater (not shown) placed in the core bar as an example of a heat source. The heating roller52heats and melts the toner when the halogen heater generates heat under the control of a controller90, which will be described below.

The pressing roller54includes, for example, a cylindrical core bar (not shown) made of aluminum fluorocarbon resin and coated with silicone rubber, and is pressed against the outer peripheral surface of the heating roller52by being urged by a spring (not shown). Ejection rollers58, which are a pair of rollers, are disposed downstream of the fixing unit50.

An ejection opening60through which the recording sheet P is ejected and a sheet output unit62on which the recording sheet P ejected through the ejection opening60is placed are provided in the upper section of the housing11. The ejection rollers58are arranged so as to block the ejection opening60. The recording sheet P to which the toner images are fixed by the fixing unit50is ejected through the ejection rollers58and placed on the sheet output unit62.

An optical scanning unit30is disposed on the left side of the image forming units20inFIG. 1in the housing11. The optical scanning unit30irradiates the photoconductors26that are rotatably arranged in the image forming units20with exposure light L. The optical scanning unit30includes a housing31, which is sectioned into an optical scanning section32(left side inFIG. 1) and a light guide section34(right side inFIG. 1) by a separation wall33that extends vertically. The separation wall33has an opening35through which light is guided from the optical scanning section32to the light guide section34.

The optical scanning section32includes a light emitting member (for example, a semiconductor laser) that emits exposure light L corresponding to each color; a polygon mirror (rotating polygon)36that is rotated by a motor (not shown) so as to deflect the exposure light L in a first scanning direction of the recording sheet P; and a reflecting mirror37that reflects the exposure light L deflected by the polygon mirror36toward the opening35.

The light guide section34includes a lens38disposed near the opening35and plural optical components (reflecting mirrors and lenses)39that guide the exposure light L that has passed through the lens38toward the photoconductors26in the image forming units20Y to20K. InFIG. 1, only the optical components on the optical path of the exposure light L guided to the image forming unit20K are denoted by reference numeral39, and the reference numeral is omitted for the other optical components. The surface (outer peripheral surface) of each photoconductor26is irradiated with the exposure light L, so that an electrostatic latent image corresponding to image information is formed on the surface of each photoconductor26.

The controller90, which controls the operation of each part of the image forming apparatus10, is provided next to the optical scanning unit30(on the left side inFIG. 1) in the housing11. An operation panel92is disposed above the fixing unit50in the housing11in such a state that the upper surface of the operation panel92is exposed. The operation panel92is an example of an operation unit that is operated by an operator to activate each part of the image forming apparatus10or to input various settings (number of pages, image density, etc.).

Referring toFIG. 3, each image forming unit20includes a photoconductor unit22disposed at an upper section and a developing unit24disposed at a lower section. The photoconductor unit22includes the photoconductor26. The developing unit24contains the toner of each color and develops the electrostatic latent image formed on the photoconductor26with the toner. An optical path23through which the exposure light L passes is formed between the photoconductor unit22and the developing unit24. The surface of the photoconductor26is irradiated with the exposure light L that passes through the optical path23.

The developing unit24includes a developing section25that visualizes the electrostatic latent image formed on the photoconductor26with the toner and a tonner supplying section27that supplies the toner to the developing section25. The developing section25and the tonner supplying section27are integrated with each other along the horizontal direction inFIG. 3. The developing section25has an opening29at a position near the photoconductor26, and a developing roller28is disposed such that the peripheral surface thereof is partially exposed at the opening29. In the present exemplary embodiment, two-component developer including carrier composed of metal particles and toner composed of resin particles will be explained as an example of the developer. However, the developer is not limited to this, and one-component developer including only toner may be used instead.

The developing roller28includes a nonmagnetic cylindrical developing sleeve (not shown) which is rotatable in the direction shown by the arrow (clockwise inFIG. 3) and a magnetic roller (not shown) which is fixed to the inner periphery of the developing sleeve and in which magnetic poles of different polarities are alternately arranged. A gear (not shown) is fixed to an end of the developing sleeve in the axial direction thereof. A rotational driving force is transmitted from a motor to the gear, so that the developing sleeve is rotated by the rotation of the gear.

The developing roller28attracts the carrier included in the developer with magnetic force, and thereby forms a magnetic brush of the developer on the surface thereof. Accordingly, the toner carried by the carrier is transported to a developing area (developer supplying position) (not shown) in which the developing roller28is opposed to the photoconductor26. Then, the electrostatic latent image formed on the photoconductor26by the exposure light L is visualized by the magnetic brush of the developer formed on the surface of the developing roller28.

A cylindrical layer-thickness regulating member64is opposed to the outer peripheral surface of the developing roller28at a position upstream of the developing area in the direction in which the developing roller28rotates. The layer-thickness regulating member64is formed of, for example, aluminum, and regulates the layer thickness of the developer supplied to the developing roller28.

A first stirring member66is rotatably supported below the developing roller28. The first stirring member66has a helical shape, and transports the toner (and the carrier) in the same direction as the axial direction of the developing roller28while stirring the toner. A gear (not shown) is fixed to an end of the first stirring member66, and the first stirring member66is rotated when a rotational driving force is transmitted from a motor (not shown) to the gear.

The toner is transported to the outer peripheral surface of the developing roller28while being stirred by the rotation of the first stirring member66. A second stirring member67and a third stirring member68are rotatably provided in the tonner supplying section27that is adjacent to the developing section25. The second and third stirring members67and68have a helical shape, and the axial direction thereof coincides with the axial direction of the developing roller28. The toner is stirred and circulated by the second and third stirring members67and68.

The photoconductor unit22includes the photoconductor26, a charging roller72, a cleaning roller74, a cleaning blade70, a screw auger76, and an erase lamp78. The photoconductor26is rotatably supported at the ends thereof by bearings (not shown) provided in the housing21. The charging roller72is opposed to the surface (outer peripheral surface) of the photoconductor26and charges the surface of the photoconductor26by using a potential difference. The cleaning roller74cleans the outer peripheral surface of the charging roller72. The cleaning blade70is an example of a cleaning member which cleans the surface of the photoconductor26by removing residual toner (hereinafter referred to as “waste toner”) that remains on the surface of the photoconductor26. The screw auger76is an example of a (first) transporting member that transports the waste toner removed by the cleaning blade70and stored in the housing21toward a first end of the photoconductor26in the rotational axis direction thereof. The erase lamp78eliminates the electric charge on the surface of the photoconductor26after the transfer process.

As illustrated inFIG. 3, the screw auger76is disposed above the photoconductor26in the direction of gravity, and is rotated by a motor (not shown). One long side (base end) of a rectangular shield member75is attached to a portion of the housing21between the screw auger76and the erase lamp78, the longitudinal direction of the shield member75coinciding with the rotational axis direction of the photoconductor26. The other long side (free end) of the shield member75is in contact (slidable contact) with the surface of the photoconductor26.

The shield member75prevents or inhibits the waste toner transported by the screw auger76from moving toward the erase lamp78or falling onto the surface (outer peripheral surface) of the photoconductor26. The shield member75is, for example, film-shaped and is formed of an elastic body so that the shield member75does not damage the surface of the photoconductor26.

Referring toFIG. 5, the shield member75is arranged such that end portions thereof overlap sealing members82and84, which will be described below. End portions of the photoconductor26press the sealing members82and84with the end portions of the shield member75interposed between the photoconductor26and the sealing members82and84.

Referring toFIG. 6, a screw auger77is provided on the housing21. The screw auger77is an example of a (second) transporting member for guiding the waste toner that has been transported by the screw auger76to a collection container80, which will be described below. The screw auger77crosses a transporting direction in which the screw auger76transports the waste toner at, for example, substantially 90 degrees and extends nearly horizontally (such that a transport path of the waste toner at the downstream side in the transporting direction of the waste toner crosses the transporting direction.

More specifically, a first end of a cylindrical member79that houses the screw auger77is integrally attached to a first end of the housing21at the downstream side in the transporting direction of the waste toner such that the waste toner may be transported from the screw auger76to the screw auger77. The housing21(the screw auger76) and the cylindrical member79(the screw auger77) are arranged so as to form an ‘L’ shape in plan view.

The screw auger77is also rotated by a motor (not shown). The screw augers76and77are preferably rotated by a single common motor. Referring toFIG. 6, the screw augers76and77are structured such that helical blades are formed on the outer peripheral surfaces of shafts.

Referring toFIGS. 4 to 6, the collection container80in which the waste toner is collected has a rectangular parallelepiped shape whose longitudinal direction coincides with the axial direction of the cylindrical member79(direction in which the screw auger77extends). The collection container80is detachably attached to a second end of the cylindrical member79.

The collection container80is replaced with a new collection container when the amount of waste toner collected therein exceeds a predetermined amount. As illustrated inFIG. 2, the collection container80is provided for each of the image forming units20Y to20K, so that the waste toners of the respective colors do not mix with each other.

Referring toFIGS. 4 and 5, the sealing member82, which is an example of a first sealing member, is provided between a second end of the housing21at the upstream side in the transporting direction of the waste toner and a second end of the photoconductor26in the rotational axis direction thereof. A gap between the second end of the housing21and the second end of the photoconductor26(gap in the transport path of the waste toner) is filled (sealed) with the sealing member82.

Similarly, the sealing member84, which is an example of a second sealing member, is provided between the first end of the housing21at the downstream side in the transporting direction of the waste toner and the first end of the photoconductor26in the rotational axis direction thereof. A gap between the first end of the housing21and the first end of the photoconductor26(gap in the transport path of the waste toner) is filled (sealed) with the sealing member84.

The sealing member82has a single-layer structure made of urethane foam (sponge). In contrast, as illustrated inFIG. 7, the sealing member84has a two-layer structure including a layer of urethane foam86and a layer of glass fiber (GF) felt88, which is a material that is denser than urethane foam86.

The term “fine” has various meanings, such as delicate, having a high surface density, and having a high elastic modulus. In this specification, it means that the sealing performance is higher than that of urethane foam86. The sealing members82and84have the same thickness, and are deformed by the same amount when they are pressed by the end portions of the photoconductor26with the shield member75interposed between the photoconductor26and the sealing members82and84. The sealing member84is positioned such that the layer of GF felt88faces the photoconductor26.

The sealing members82and84at the upstream side and the downstream side, respectively, in the transporting direction of the waste toner have different structures (different materials) for the following reason. That is, the stress applied by the screw auger76at the downstream side in the transporting direction of the waste toner is larger than that applied by the screw auger76at the upstream side, and the waste toner that has been transported easily accumulates at the downstream side. When the waste toner accumulates in a certain section, there is a high possibility that the waste toner will fall through a gap in that section. This is the reason why the sealing member84at the downstream side in the transporting direction of the waste toner is structured so as to provide a high sealing performance (tightness).

A feeder unit (not shown) is disposed at the second end of the housing21at the upstream side in the transporting direction of the waste toner. Accordingly, the feeder unit is prevented from being contaminated by the waste toner. The cleaning member for cleaning the surface of the photoconductor26is not limited to the illustrated cleaning blade70, and may instead be, for example, a brush.

The operation of the cleaning device and the image forming apparatus10having the above-described structure will now be explained. First, an image forming process of the image forming apparatus10will be explained. Referring toFIG. 1, when the units of the image forming apparatus10are activated, the image data subjected to image processing performed by the controller90is converted into color gradation data for each color and is successively output to the optical scanning unit30.

The optical scanning unit30emits the exposure light L in accordance with the color gradation data of the respective colors, and scans the surface (outer peripheral surface) of each photoconductor26that has been charged by the corresponding charging roller72with the exposure light L. Thus, an electrostatic latent image is formed on the surface of each photoconductor26. The electrostatic latent images formed on the surfaces of the photoconductors26are developed (visualized) by the developing rollers28as toner images (developer images) of respective colors, which are yellow (Y), magenta (M), cyan (C), and black (K).

Next, the toner images of the respective colors that have been successively formed on the photoconductors26in the image forming units20Y,20M,20C, and20K are successively transferred by the transfer rollers48onto the recording sheet P that has been transported from the sheet feeding unit12. The recording sheet P onto which the toner images have been transferred is transported toward the fixing unit50by the transporting unit40.

In the fixing unit50, the toner images of the respective colors on the recording sheet P are fixed to the recording sheet P by being heated and pressurized by the heating roller52and the pressing roller54. Then, the recording sheet P to which the toner images are fixed is ejected toward the sheet output unit62by the ejection rollers58.

Next, the operation of the cleaning device (photoconductor unit22) in each image forming unit20will be described. The waste toner that remains on the surface of the photoconductor26instead of being transferred onto the recording sheet P is scraped off the surface of the photoconductor26by the cleaning blade70and is collected in the housing21. Then, the waste toner is transported by the screw auger76in a direction from the second end to the first end of the housing21(from the side visible inFIG. 3to the side opposite thereto).

At this time, the shield member75inhibits the waste toner from moving toward the erase lamp78or falling onto the surface of the photoconductor26, and the sealing members82and84prevent the waste toner from falling out of the housing21through the gaps between the end portions of the housing21and the end portions of the photoconductor26.

In particular, the sealing member84at the downstream side in the transporting direction of the waste toner has a higher sealing performance (tightness) for sealing the end portion of the photoconductor26than that of the sealing member82at the upstream side in the transporting direction of the waste toner. Therefore, even when the waste toner accumulates in a section where the toner is transported from the screw auger76to the screw auger77, the waste toner is prevented from passing through the gap between the shield member75and the sealing member84and falling out of the housing21.

More specifically, the screw auger76is disposed above the photoconductor26in the direction of gravity, and the screw augers76and77extend nearly horizontally and cross each other at substantially 90 degrees. In other words, the screw augers76and77are arranged in an ‘L’ shape in plan view. A delivery section in which the waste toner is delivered from the screw auger76to the screw auger77receives stress from the waste toner (the waste toner easily accumulates and falls out).

Moreover, the screw auger77transfers the waste toner nearly horizontally to collect the waste toner in the collection container80. Therefore, compared to the structure in which the waste toner is collected in the collection container80by using the force of gravity, the above-described delivery section receives a larger stress from the waste toner (the waste toner more easily accumulates and falls out).

However, in this example, the sealing member84at the delivery section in which a large stress is applied (at the downstream side in the transporting direction of the waste toner) is made of a denser material than the material of the sealing member82at a section in which the stress is small (at the upstream side in the transporting direction of the waste toner). For example, the sealing member84includes GF felt88. Thus, high sealing performance (tightness) is ensured in the delivery section. Accordingly, even when the waste toner accumulates in the delivery section, the waste toner may be prevented from falling out of the housing21.

Here, only the sealing member84at the delivery section in which a large stress is applied (at the downstream side in the transporting direction of the waste toner) has a two-layer structure including the layers of urethane foam86and GF felt88. Therefore, compared to the case in which the sealing member82at the section in which the stress is small (at the upstream side in the transporting direction of the waste toner) also has a two-layer structure including the layers of urethane foam86and GF felt88, the manufacturing costs may be reduced.

Although the cleaning device and the image forming apparatus10according to the present exemplary embodiment have been explained with reference to the accompanying drawings, the cleaning device and the image forming apparatus10according to the present exemplary embodiment are not limited to this. For example, the present exemplary embodiment is also applicable to the case in which an intermediate transfer belt (not shown) functions as an image carrier. In this case, the rotational axis direction of each of the rollers (not shown) around which the intermediate transfer belt is wrapped serves as the rotational axis direction of the image carrier according to the present exemplary embodiment.

The sealing member84according to the present exemplary embodiment is particularly effective for the structure in which the waste toner easily accumulates at the downstream side in the transporting direction of the waste toner. The structure of the sealing member84is not limited to the illustrated two-layer structure (multilayer structure). For example, the sealing member84may have a single-layer structure as long as the material thereof is denser than the material of the sealing member82. In addition, the transporting member is not limited to the screw auger77.