Patent Application
20170023907
This application is based upon and claims the benefit of priority from the corresponding Japanese Patent Application No. 2015-147061 filed on Jul. 24, 2015, the entire contents of which are incorporated herein by reference.
The present disclosure relates to a cleaning device and to an image forming apparatus incorporating the cleaning device. More particularly, the present disclosure relates to a cleaning device that removes toner that remains attached to an image carrying member, and to an image forming apparatus incorporating such a cleaning device.
Conventionally, image forming apparatuses such as copiers and printers incorporate a cleaning device that removes toner that remains attached to an image carrying member such as a photosensitive drum or an intermediate transfer belt. The cleaning device includes a housing having formed in it an opening that faces the image carrying member, and includes a cleaning blade for removing toner that remains attached to the image carrying member while being in contact with the circumferential surface of the image carrying member. On the housing, on the upstream side of the opening with respect to the rotation direction of the image carrying member, a sealing member that abuts on the circumferential surface of the image carrying member is provided for preventing waste toner inside the housing from leaking out through a gap between the housing and the image carrying member.
According to one aspect of the present disclosure, a cleaning device includes a housing, a cleaning blade, a first sealing member, and a second sealing member. The housing has formed in it an opening that faces an image carrying member and a waste toner storage for storing waste toner scraped off the surface of the image carrying member. The cleaning blade is arranged on the housing, on the downstream side of the opening with respect to the rotation direction of the image carrying member. The cleaning blade removes toner that remains attached to the image carrying member while being in contact with the circumferential surface of the image carrying member with its tip end part pointed to the upstream side with respect to the rotation direction of the image carrying member. The first sealing member is arranged on the housing, on the upstream side of the opening with respect to the rotation direction of the image carrying member. The first sealing member prevents waste toner inside the housing from leaking out through a gap between the housing and the image carrying member, owing to the first sealing member abutting on the circumferential surface of the image carrying member with its tip end part pointed to the downstream side with respect to the rotation direction of the image carrying member. The second sealing member is arranged on the housing, on the upstream side of the opening with respect to the rotation direction of the image carrying member and on the downstream side of the first sealing member with respect to the rotation direction of the image carrying member. The second sealing member prevents waste toner inside the housing from leaking out through a gap between the housing and the image carrying member, owing to the second sealing member abutting on the circumferential surface of the image carrying member with its tip end part pointed to the downstream side with respect to the rotation direction of the image carrying member.
Further features and advantages of the present disclosure will become apparent from the description of embodiments given below.
Hereinafter, embodiments of the present disclosure will be described with reference to the accompanying drawings.
With reference to
In this embodiment, the image forming apparatus 100 (here a color printer) is a quadruple-tandem-type color printer that performs image formation by use of four photosensitive drums 1a, 1b, 1c, and 1d, corresponding to four different colors (yellow, cyan, magenta, and black) respectively, which are arranged side by side.
Inside the apparatus main body of the image forming apparatus 100, four image forming portions Pa, Pb, Pc and Pd are arranged in this order from the left side in
In these image forming portions Pa to Pd are respectively arranged the photosensitive drums 1a to 1d that carry visible images (toner images) of the different colors. Moreover, an intermediate transfer belt (image carrying member) 8 that rotates in the counter-clockwise direction in
Sheets P to which toner images are to be transferred are stored in a sheet feed cassette 16 in a lower part of the apparatus, and are transported via a feeding roller 12a and a registration roller pair 12b to the secondary transfer roller 9. As the intermediate transfer belt 8, a dielectric resin sheet is used, which typically is, for example, a seamless belt having no seam. The intermediate transfer belt 8 and the secondary transfer roller 9 are driven to rotate at the same linear velocity as the photosensitive drums 1a to 1d by a belt driving motor (unillustrated). In the image forming portion Pd, a belt cleaning device (cleaning device) 30 is arranged for removing toner left unused on the surface of the intermediate transfer belt 8.
Now, the image forming portions Pa to Pd will be described. Around and under the photosensitive drums 1a to 1d, which are rotatably arranged, there are arranged charging devices 2a, 2b, 2c, and 2d for electrostatically charging the photosensitive drums 1a to 1d, an exposure unit 5 for exposing the photosensitive drums 1a to 1d to light based on image data, developing units 3a, 3b, 3c, and 3d for developing, by use of toner, electrostatic latent images formed on the photosensitive drums 1a to 1d, and cleaning devices 7a, 7b, 7c, and 7d for collecting and removing developer (toner) left unused on the photosensitive drums 1a to 1d after toner images have been transferred.
When image data is fed in from a host device such as a personal computer, the surfaces of the photosensitive drums 1a to 1d are first electrostatically charged uniformly by the charging devices 2a to 2d and are then irradiated with light based on the image data by the exposure unit 5, and thereby electrostatic latent images based on the image data are formed on the photosensitive drums 1a to 1d respectively. The developing units 3a to 3d have developing rollers arranged opposite the photosensitive drums 1a to 1d, and are charged with predetermined amounts of two-component developer containing toner of different colors, namely yellow, cyan, magenta, and black respectively.
When the proportion of toner contained in the two-component developer stored in the developing units 3a to 3d falls below a predetermined value through formation of toner images, which will be described later, toner is supplied from toner containers 4a to 4d to the developing units 3a to 3d. The toner is fed from the developing units 3a to 3d onto the photosensitive drums 1a to 1d, and electrostatically attaches to them, thereby forming toner images based on the electrostatic latent images formed by exposure to light from the exposure unit 5.
Then, an electric field is applied, by primary transfer rollers 6a to 6d, between the primary transfer rollers 6a to 6d and the photosensitive drums 1a to 1d with a predetermined transfer voltage, and the yellow, cyan, magenta, and black toner images on the photosensitive drums 1a to 1d are primarily transferred to the intermediate transfer belt 8. These images of four colors are formed in a predetermined positional relationship prescribed to form a predetermined full-color image. Thereafter, in preparation for subsequent formation of new electrostatic latent images, toner left unused on the surfaces of the photosensitive drums 1a to 1d is removed by the cleaning devices 7a to 7d.
The intermediate transfer belt 8 is wound around a following roller 10 and a driving roller 11. As the driving roller 11 rotates by being driven by the above-mentioned belt driving motor, the intermediate transfer belt 8 rotates in the counter-clockwise direction; meanwhile, a sheet P is transported from the registration roller pair 12b, with predetermined timing, to a nip (secondary transfer nip) between the secondary transfer roller 9, which is arranged next to the intermediate transfer belt 8, and the intermediate transfer belt 8. At the nip, the full-color image is secondarily transferred to the sheet P. The sheet P having the toner images transferred to it is transported to the fixing device 13.
The sheet P transported to the fixing device 13 is heated and pressed while passing through a fixing nip between a fixing roller pair 13a composed of a heating roller and a pressing roller, and thereby the toner images are fixed to the surface of the sheet P to form the predetermined full-color image. The sheet P having the full-color image formed on it is, via a transport roller pair 15, distributed between different transport directions by a branching member 21 arranged in a branching portion of a sheet transport passage 18. The sheet P is then, as it is (or after being transported to a double-sided transport passage 22 and being subjected to double-sided copying), discharged via a discharge roller pair 19 onto a discharge tray 20.
Specifically, the sheet transport passage 18 branches into left and right passages on the downstream side of the transport roller pair 15. Of these passages, one (the passage that branches in the leftward direction in
Thereafter, the discharge roller pair 19 is rotated in the reverse direction and the branching member 21 is swung to be substantially horizontal, so that the sheet P is guided, along the top surface of the branching member 21, to the double-sided transport passage 22. The sheet P is then, with the image side reversed, transported once again to the secondary transfer roller 9. Then, the next image formed on the intermediate transfer belt 8 is transferred by the secondary transfer roller 9 to the side of the sheet P on which no image has yet been formed. The sheet P is then transported to the fixing device 13, where the toner image is fixed, and is then discharged onto the discharge tray 20.
Next, the structure of and around the belt cleaning device 30 will be described.
As shown in
The housing 31 has an opening 31a facing the intermediate transfer belt 8, and has a waste toner storage 31b for storing waste toner scraped off the surface of the intermediate transfer belt 8.
The cleaning blade 32 is fixed to the housing 31, on the downstream side (on the left side in
At a position facing the cleaning blade 32 across the intermediate transfer belt 8, there is arranged a cleaning counter roller 40 that receives a pressing force from the cleaning blade 32. The cleaning counter roller 40 is driven to rotate in the counter-clockwise direction in
The unused toner removed from the surface of the intermediate transfer belt 8 by the cleaning blade 32 is, as the collection screw 33 rotates, discharged out of the belt cleaning device 30 and transported to a toner collection container (unillustrated) to be stored in it.
The first sealing member 34 is fitted to the housing 31, on the upstream side (on the right side in
The second sealing member 35 is fitted to the housing 31, on the upstream side (on the right side in
Now, in this embodiment, let the inclination angle of the first sealing member 34 with respect to the circumferential surface of the intermediate transfer belt 8 be θ1, and let the inclination angle of the second sealing member 35 with respect to the circumferential surface of the intermediate transfer belt 8 be θ2, then θ1>θ2 holds. Specifically, the inclination angle θ1 satisfies 30°<θ1<90°, and the inclination angle θ2 satisfies 10°<θ2<40°. In this embodiment, the first and second sealing members 34 and 35 have substantially equal rigidity, surface roughness, and friction coefficients.
In this embodiment, as described above, on the housing 31 are provided, on the upstream side of the opening 31a with respect to the rotation direction of the intermediate transfer belt 8, the first and second sealing members 34 and 35 that prevent, by abutting on the circumferential surface of the intermediate transfer belt 8, waste toner inside the housing 31 from leaking out through a gap between the housing 31 and the intermediate transfer belt 8. That is, two sealing members are provided along the rotation direction of the intermediate transfer belt 8. Thus, water toner inside the housing 31 can be prevented from leaking out through a gap between the housing 31 and the intermediate transfer belt 8.
As described above, let the inclination angle of the first sealing member 34 with respect to the circumferential surface of the intermediate transfer belt 8 be θ1, and let the inclination angle of the second sealing member 35 with respect to the circumferential surface of the intermediate transfer belt 8 be θ2, then θ1>θ2 holds. This permits paper dust or the like to stay at a place where the first sealing member 34 and the intermediate transfer belt 8 are in contact with each other, and also prevents paper dust or the like from staying at a place where the second sealing member 35 and the intermediate transfer belt 8 are in contact with each other, so as to thereby prevent a tip end part of the second sealing member 35 from leaving the circumferential surface of the intermediate transfer belt 8. Thus, with the second sealing member 35, it is possible to achieve sealing and thereby effectively prevent waste toner inside the housing 31 from leaking.
As described above, the inclination angle θ1 satisfies 30°<θ1<90°, and the inclination angle θ2 satisfies 10°<θ2<40°. This permits paper dust or the like to easily stay at the place where the first sealing member 34 and the intermediate transfer belt 8 are in contact with each other, and thus with the second sealing member 35, it is possible to achieve sealing easily.
As a second embodiment, a description will be given of a case where the present disclosure is applied to the cleaning devices 7a to 7d that remove toner that remains attached to the photosensitive drums (image carrying members) 1a to 1d. Although the following description deals with, as an example, a structure of and around the photosensitive drum 1a, the cleaning devices 7b to 7d that remove toner attached to the photosensitive drums 1b to 1d have basically the same structure, and thus no overlapping description will be repeated.
As shown in
The cleaning brush 36 performs a scratching process in which it scratches off toner that remains attached to the surface of the photosensitive drum 1a after primary transfer, as a preparatory process to permit the cleaning blade 32 to effectively scrape off the unused toner. The cleaning brush 36 is formed in the shape of a brush with a large number of brush fibers 36b arranged erect radially from the circumferential surface of a rotary shaft 36a which is arranged parallel to the rotary shaft of the photosensitive drum 1a. The cleaning brush 36 is driven to rotate by an unillustrated driving means in the same direction (the counter-clockwise direction) as the photosensitive drum 1a at the plane of contact with it so as to transport toner toward the downstream side with respect to the rotation direction (the clockwise direction) of the photosensitive drum 1a, that is, toward the side where the collection screw 33 is arranged.
In this embodiment, as in the previously-described first embodiment, let the inclination angle of the first sealing member 34 with respect to the circumferential surface of the photosensitive drum 1a be θ1, and let the inclination angle of the second sealing member 35 with respect to the circumferential surface of the photosensitive drum 1 a be θ2, then θ1>θ2 holds. The inclination angle θ1 satisfies 30°<θ1<90°, and the inclination angle θ2 satisfies 10°<θ2 <40°.
Otherwise, the structure and effects in the second embodiment are similar to those in the previously-described first embodiment.
It should be understood that the embodiments disclosed herein are in every aspect illustrative and not restrictive. The scope of the present disclosure is defined not by the description of embodiments given above but by the appended claims, and encompasses many modifications and variations made in the sense and scope equivalent to those of the claims.
For example, although an example has been dealt with in which the present disclosure is applied to a color printer, this is not meant as any limitation. Needless to say, the present disclosure is applicable to various image forming apparatuses provided with a cleaning device that removes toner that remains attached to an image carrying member, examples including monochrome printers, color copiers, monochrome copiers, digital multifunction peripherals, facsimile machines, etc.
Although the above-described embodiments deal with an example where the first and second sealing members 34 and 35 are arranged such that θ1>θ2 holds, this is in no way meant to limit the present disclosure. For example, the first and second sealing members 34 and 35 may be arranged such that θ1≦θ2 holds.
Although the above-described embodiments deal with an example where the first and second sealing members 34 and 35 are arranged such that θ1>θ2 so that the first sealing member 34 makes paper dust or the like stay and that the second sealing member 35 achieves sealing, this is in no way meant to limit the present disclosure. For example, the first and second sealing members 34 and 35 may be arranged such that θ1=θ2 holds, and the first sealing member 34 may be given higher rigidity than the second sealing member 35. Also with this configuration, it is possible to permit paper dust or the like to stay at a place where the first sealing member 34 and an image carrying member (the intermediate transfer belt 8, the photosensitive drums 1a to 1d) are in contact with each other, and in addition to prevent paper dust or the like from staying at a place where the second sealing member 35 and the image carrying member are in contact with each other, so as to thereby prevent a tip end part of the second sealing member 35 from leaving the circumferential surface of the image carrying member. Thus, with the second sealing member 35, it is possible to achieve sealing and thereby effectively prevent waste toner inside the housing 31 from leaking.
Or, for example, the first and second sealing members 34 and 35 may be arranged such that θ1=θ2 holds, and the first sealing member 34 may be given smaller surface roughness than the second sealing member 35 on their respective surfaces which abut on the image carrying member. In this case, the first sealing member 34 has a higher coefficient of friction than the second sealing member 35 on their respective surfaces which abut on the image carrying member. Also with this configuration, it is possible to permit paper dust or the like to stay at a place where the first sealing member 34 and the image carrying member are in contact with each other, and in addition to prevent paper dust or the like from staying at a place where the second sealing member 35 and the image carrying member are in contact with each other, so as to thereby prevent a tip end part of the second sealing member 35 from leaving the circumferential surface of the image carrying member. Thus, with the second sealing member 35, it is possible to achieve sealing and thereby effectively prevent waste toner inside the housing 31 from leaking.
Although the above-described second embodiment deals with an example where a cleaning device according to the present disclosure is used for removing toner left unused on the surface of the photosensitive drum 1a of a color printer, this is in no way meant to limit the present disclosure. Paper dust is more likely to attach to the surface of the photosensitive drum 1a in image forming apparatuses such as monochrome printers and monochrome copiers in which a toner image is transferred to a sheet P directly from the photosensitive drum 1a without first being transferred to an intermediate transfer belt (intermediate transfer member). Thus, when a cleaning device according to the present disclosure is used for the purpose of removing toner left unused on the surface of the photosensitive drum 1a, it is more effective to incorporate it in monochrome image forming apparatuses than in color image forming apparatuses.
The technical scope of the present disclosure encompasses any structure obtained by combining together different features from the above-described embodiments and modified examples as necessary.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2015-147061 | Jul 2015 | JP | national |
