Patent Grant
10061243
This patent application is based on and claims priority pursuant to 35 U.S.C. § 119(a) to Japanese Patent Application No. 2016-129176, filed on Jun. 29, 2016, in the Japan Patent Office, the entire disclosure of which is hereby incorporated by reference herein.
Technical Field
Embodiments of the present disclosure generally relate to a fixing device and an image forming apparatus incorporating the fixing device, and more particularly, to a fixing device for fixing a toner image onto a recording medium, and an image forming apparatus for forming an image on a recording medium with the fixing device.
Related Art
Various types of electrophotographic image forming apparatuses are known, including copiers, printers, facsimile machines, and multifunction machines having two or more of copying, printing, scanning, facsimile, plotter, and other capabilities. Such image forming apparatuses usually form an image on a recording medium according to image data. Specifically, in such image forming apparatuses, for example, a charger uniformly charges a surface of a photoconductor as an image bearer. An optical writer irradiates the surface of the photoconductor thus charged with a light beam to form an electrostatic latent image on the surface of the photoconductor according to the image data. A developing device supplies toner to the electrostatic latent image thus formed to render the electrostatic latent image visible as a toner image. The toner image is then transferred onto a recording medium either directly, or indirectly via an intermediate transfer belt. Finally, a fixing device applies heat and pressure to the recording medium bearing the toner image to fix the toner image onto the recording medium. Thus, the image is formed on the recording medium.
Such a fixing device typically includes a fixing rotator, such as a roller, a belt, and a film, and a pressure rotator, such as a roller and a belt, pressed against the fixing rotator. The fixing rotator and the pressure rotator apply heat and pressure to the recording medium, melting and fixing the toner image onto the recording medium while the recording medium is conveyed between the fixing rotator and the pressure rotator.
In such a fixing device, toner melting at the fixing nip may partly adhere to the surface of at least one of the fixing rotator and the pressure rotator. To address this circumstance, the fixing device often includes a cleaning mechanism to remove the toner from the at least one of the fixing rotator and the pressure rotator, thus cleaning the surface of the at least one of the fixing rotator and the pressure rotator.
In one embodiment of the present disclosure, a novel fixing device is described that includes a fixing rotator, a pressure rotator, and a cleaning device. The pressure rotator contacts the fixing rotator to form a fixing nip between the fixing rotator and the pressure rotator, through which a recording medium bearing a toner image is conveyed. The cleaning device cleans a surface of at least one of the fixing rotator and the pressure rotator. The cleaning device includes a cleaning web, a web holder, a winder, a cleaning pressure rotator, a pressure applier, and a temporary holder. The cleaning web slides over the at least one of the fixing rotator and the pressure rotator to clean the surface of the at least one of the fixing rotator and the pressure rotator. The web holder holds and sends out the cleaning web. The winder winds the cleaning web. The cleaning pressure rotator presses the cleaning web against the at least one of the fixing rotator and the pressure rotator. The pressure applier presses against the cleaning web along a width direction of the cleaning web perpendicular to a direction in which the cleaning web is wound. The temporary holder temporarily holds the pressure applier.
Also described is a novel image forming apparatus incorporating the fixing device.
A more complete appreciation of the disclosure and many of the attendant advantages thereof will be more readily obtained as the same becomes better understood by reference to the following detailed description of embodiments when considered in connection with the accompanying drawings, wherein:
The accompanying drawings are intended to depict embodiments of the present disclosure and should not be interpreted to limit the scope thereof. Also, identical or similar reference numerals designate identical or similar components throughout the several views.
In describing embodiments illustrated in the drawings, specific terminology is employed for the sake of clarity. However, the disclosure of this patent specification is not intended to be limited to the specific terminology so selected and it is to be understood that each specific element includes all technical equivalents that have the same function, operate in a similar manner, and achieve similar results.
Although the embodiments are described with technical limitations with reference to the attached drawings, such description is not intended to limit the scope of the disclosure and not all of the components or elements described in the embodiments of the present disclosure are indispensable to the present disclosure.
In a later-described comparative example, embodiment, and exemplary variation, for the sake of simplicity like reference numerals are given to identical or corresponding constituent elements such as parts and materials having the same functions, and redundant descriptions thereof are omitted unless otherwise required.
As used herein, the singular forms “a”, “an”, and “the” are intended to include the plural forms as well, unless the context clearly indicates otherwise.
Referring now to the drawings, embodiments of the present disclosure are described below.
Initially with reference to
A fixing device illustrated in
A part of the toner T melting at the fixing nip may fail to be fixed onto the sheet S and adhere to the surface of the fixing roller 2. This phenomenon is called an offset.
The toner T adhering to the surface of the fixing roller 2 at the fixing nip moves as the fixing roller 2 rotates. The toner T transferred to the fixing roller 2 from the sheet S by the offset may contaminate components that contact the fixing roller 2, such as a sheet separation claw 11, a temperature sensor 4, and the pressure roller 3. The temperature sensor 4 detects a surface temperature of the fixing roller 2. The toner T adhering to the surface of the fixing roller 2 may adhere to and contaminate a next sheet S conveyed through the fixing nip.
To address these circumstances, the fixing device incorporates the cleaning mechanism 10X1 of
Specifically, the cleaning mechanism 10X1 includes, e.g., a cleaning web 5, a web holder 6, a web roller 7, and a cleaning pressure roller 8. The cleaning web 5 slides over the surface of the fixing roller 2 to clean the surface of the fixing roller 2. The web holder 6 holds and sends out the cleaning web 5. The web roller 7 is a winder that winds the cleaning web 5. The cleaning pressure roller 8 is a cleaning pressure rotator that presses the cleaning web 5 against the fixing roller 2, thereby forming an area of contact, herein referred to as a web nip, between the cleaning web 5 and the fixing roller 2. The web holder 6 sends out the cleaning web 5 in a direction X as illustrated in
The web roller 7 is timed to rotate to wind the cleaning web 5 in the direction X. As the web roller 7 winds the cleaning web 5, a new portion (i.e., a portion yet to contact the fixing roller 2) of the cleaning web 5 gradually moves from the web holder 6 to the web nip between the cleaning web 5 and the fixing roller 2. Thus, the cleaning web 5 of the cleaning mechanism 10X1 removes the toner T from the surface of the fixing roller 2.
However, if the cleaning web 5 waves or is wrinkled, the web nip between the cleaning web 5 and the fixing roller 2 may be secured insufficiently, degrading cleaning performance.
To address this circumstance, the fixing device may incorporate the cleaning mechanism 10X2 of
Upon replacement of the cleaning web 5 with a new one, pressure from the flat spring 9 may hamper the replacement. Generally, upon replacement of the cleaning web 5, the web holder 6 is replaced with a new one. Since a new cleaning web 5 is wound around the new web holder 6, the new web holder 6 has an increased outer diameter. Therefore, an increased reaction force is applied to the flat spring 9 that presses against the new cleaning web 5, making it hard to hold the flat spring 9 manually or with a provisional jig.
To address this circumstance, a fixing device 1 of an image forming apparatus 100 includes a cleaning web unit 10 according to a first embodiment of the present disclosure.
Referring now to
With the cleaning web unit 10, the fixing device 1 addresses difficulty in incorporating a flat spring in a cleaning web mechanism due to pressure of the flat spring, facilitating replacement of a cleaning web.
A cleaning mechanism as a cleaning device according to the first embodiment is different from the cleaning mechanism 10X2 of
The cleaning web unit 10 includes a temporary holder 90 that temporarily holds the flat spring 9, a remover for the cleaning pressure roller 8, and a unit housing that supports, e.g., the web holder 6 and the cleaning pressure roller 8. It is to be noted that the unit housing is a device housing of the fixing device 1.
More specifically, as illustrated in
The web holder 6 and the cleaning pressure roller 8 are rotatably supported between the frames 50L and 50R. Similarly, the web roller 7 is rotatably supported. A U-shaped groove 53 is formed in each of the frames 50L and 50R. A shaft 8a of the cleaning pressure roller 8 is fit into and removed from the groove 53.
The frame 50L is disposed on a first end portion of the cleaning web unit 10 in a width direction Y thereof, which is also a width direction of the cleaning web 5. Specifically, in
As illustrated in
The flat spring 9 is a thin plate made of stainless steel, which is a metal elastic body, having a given thickness. As illustrated in
As illustrated in
Alternatively, if such a maximum effectiveness is an option, the flat spring 9 may be disposed so as to press against the cleaning web 5 at a position closer to the web holder 6 between the web holder 6 and the cleaning pressure roller 8.
When the flat spring 9 is disposed to press against the cleaning web 5 on the outer circumferential surface of the web holder 6 upon replacement of the cleaning web 5, the acute angle θ formed by the secured face 9a and the pressure face 9b increases compared to the acute angle θ before assembly. In other words, a bent portion of the flat spring 9 is forced to open as the flat spring 9 receives an increased reaction force from the cleaning web 5. Such an increased reaction force makes it hard to hold a flat spring in a typical cleaning mechanism. Especially, upon replacement of a cleaning web, a new web holder has a maximum outer diameter because a new cleaning web is wound around the new web holder. Therefore, an increased reaction force is applied to the flat spring that presses against the new cleaning web, making it hard to hold the flat spring, resulting in difficulty in incorporation of the flat spring in the typical cleaning mechanism.
As the cleaning web 5 on the outer circumferential surface of the web holder 6 is used, the outer diameter of the web holder 6 decreases to minimum. According to the first embodiment, the flat spring 9 is configured to press against the cleaning web 5 on the outer circumferential surface of the web holder 6 having a minimum outer diameter. A bent surface 9c of the flat spring 9 prevents the flat spring 9 from catching the cleaning web 5 when the flat spring 9 presses against the cleaning web 5.
As illustrated in
In
In
Thus, the temporary holder 90 is constructed of the convex portion 52 of the frame 50L, the square hole 62 of the holder frame 60, the hole 51 of the frame 50R, and the pin 61 of the holder frame 60. When incorporating the flat spring 9 into the cleaning web unit 10 via the holder frame 60 upon replacement of the cleaning web 5, the temporary holder 90 temporarily holds the flat spring 9 in pressure contact with the cleaning web 5, thus securing the flat spring 9 to the frames 50L and 50R. The flat spring 9 is held by the holder frame 60 projecting beyond each end portion of the flat spring 9 in a width direction of the flat spring 9, that is, in the width direction Y.
Now, a description is given of operation of the temporary holder 90. On the right side in
As described above, upon replacement of the web holder 6, a new web holder 6 has a maximum outer diameter because the new web holder 6 holds a new cleaning web 5. As illustrated in
As illustrated in
In the state of
In the state of
In the coupling completion state, as illustrated in
As described above, according to the first embodiment, the temporary holder 90 temporarily holds the flat spring 9 when the flat spring 9 is incorporated into the cleaning web unit 10 upon replacement of the cleaning web 5. Accordingly, work efficiency is enhanced upon replacement of the cleaning web 5. Further, according to the first embodiment, working hours for the replacement is reduced compared to typical working hours for replacement of a cleaning web. As a consequence, operation cost can be reduced.
In the cleaning mechanism 10X2 of
Referring now to
As illustrated in
The holder 65L accommodates a first bearing 67 and a first compression spring 68 inside the holder 65L. The first bearing 67 rotatably supports the first end portion of the shaft 8a of the cleaning pressure roller 8. The first compression spring 68 biases the first bearing 67 in a direction to press the cleaning pressure roller 8 toward the fixing roller 2. The holder 65R accommodates a second bearing 67 and a second compression spring 68 inside the holder 65R. The second bearing 67 rotatably supports the second end portion of the shaft 8a of the cleaning pressure roller 8. The second compression spring 68 biases the second bearing 67 in the direction to press the cleaning pressure roller 8 toward the fixing roller 2. Convex portions formed on opposed sides of the first bearing 67 are engaged with respective recessed portions formed opposite to each other inside the holder 65L. Thus, the first bearing 67 is supported movably with a biasing force of the first compression spring 68. Similarly, convex portions formed on opposed sides of the second bearing 67 are engaged with respective recessed portions formed opposite to each other inside the holder 65R. Thus, the second bearing 67 is supported movably with a biasing force of the second compression spring 68.
Each of the first and second end portions of the shaft 8a of the cleaning pressure roller 8 has a step portion. The first bearing 67 rotatably supports the step portion (i.e., smaller-diameter portion) of the first end portion of the shaft 8a of the cleaning pressure roller 8. Similarly, the second bearing 67 rotatably supports the step portion (i.e., smaller-diameter portion) of the second end portion of the shaft 8a of the cleaning pressure roller 8.
As illustrated in
As described above, the holder 65L holds the first end portion of the shaft 8a of the cleaning pressure roller 8. By contrast, the holder 65R holds the second end portion of the shaft 8a of the cleaning pressure roller 8. The holders 65L and 65R are independently disposed. Specifically, the holders 65L and 65R are disposed symmetrically about a center line in a width direction of the cleaning pressure roller 8, that is, in the width direction Y.
When the screw 66 is removed, the holder 65 is removed from the frame 50. For example, when the screw 66 that secures the holder 65L to the frame 50L is removed, the holder 65L is removed from the frame 50L. Thereafter, when the first end portion of the shaft 8a of the cleaning pressure roller 8 is drawn from the U-shaped groove 53 of the frame 50L upper leftward in
Thus, according to the first embodiment, the holder 65L holding and securing the first end portion of the shaft 8a of the cleaning pressure roller 8 and the holder 65R holding and securing the second end portion of the shaft 8a of the cleaning pressure roller 8 are independently disposed at the first end portion of the cleaning pressure roller 8 and the second end portion of the cleaning pressure roller 8, respectively. Accordingly, work efficiency is enhanced upon replacement of the cleaning pressure roller 8. Further, working hours for the replacement is reduced compared to typical working hours for replacement of a cleaning pressure roller. As a consequence, operation cost can be reduced.
Referring now to
In
The image forming apparatus 100 includes an automatic document reader A to automatically read a sheet document. A sheet feeding roller C feeds the document placed on a document tray B to a position where the document meets a document sensor G. The document sensor G reads an image on a front side of the document passing before the document sensor G at a given speed. Data of the image thus read by the document sensor G is subjected to image processing such as various types of correction and compression. The image data thus processed is sequentially stored in an image memory.
A writing unit 49 includes, a laser output unit 19, an imaging lens 21, and a mirror 22. The writing unit 49 irradiates a photoconductor 30 with a laser beam. On the photoconductor 30, a toner image is formed. In other words, the photoconductor 30 is an image bearer that bears a toner image.
To provide a fuller understanding of the embodiments of the present disclosure, a description is now given of an image forming operation of the image forming apparatus 100 to print the image formed on the photoconductor 30, with continued reference to
A first sheet feeder 26, a second sheet feeder 27, and a third sheet feeder 28 feed a plurality of sheets S (i.e., recording media) resting on a first tray 23, a second tray 24, and a third tray 25, respectively, one by one to a vertical conveyance unit 29. The vertical conveyance unit 29 feeds the sheet S to a position before the photoconductor 30.
The writing unit 49 irradiates the photoconductor 30 with the laser beam to form a latent image on the photoconductor 30 according to the image data retrieved from the image memory. A developing device 35 develops the latent image with toner, rendering the latent image visible as a toner image. Thus, the toner image is formed on the photoconductor 30.
While the sheet S is conveyed on a conveyor belt 31 at the same speed as a rotational speed of the photoconductor 30 in synchronization with movement of the toner image thus formed on the photoconductor 30, the toner image is transferred onto the sheet S from the photoconductor 30. Subsequently, the sheet S bearing the toner image is conveyed to the fixing device 1 in a direction of conveyance of the sheet S as a recording medium conveyance direction. The fixing device 1, disposed downstream from the photoconductor 30 in the direction of conveyance of the sheet S, fixes the toner image onto the sheet S. A sheet ejection unit 32 outputs the sheet S bearing the fixed toner image onto, e.g., a first output tray 33.
Upon duplex printing to form images on both sides of the sheet S, the sheet ejection unit 32 switches a reverse passage switching claw to convey the sheet S, fed from one of the first through third trays 23 through 25 and bearing the toner image on a front side, to a duplex printing passage 38, instead of directing the sheet S to the first output tray 33. The sheet S is conveyed along the duplex printing passage 38 to a reverse unit 37 in a duplex printing conveyance unit 36. Then, the sheet S is halted on a switchback conveyance passage 41. A switchback conveyor sends out the sheet S in a reverse direction (i.e., re-feeding direction). A reverse sheet-ejection switching claw directs the sheet S downwards to reverse the sheet S. The sheet S thus reversed is conveyed to an intermediate conveyance passage 43 located below the reverse sheet-ejection switching claw. Then, an intermediate conveyor 40 and an exit conveyor 42, each of which is connected to a drive source, send the sheet S to the vertical conveyance unit 29. The sheet S is conveyed through the vertical conveyance unit 29 again to reach the fixing device 1 where another toner image is fixed onto a back side of the sheet S. Then, the sheet S bearing the images on both sides is ejected from a housing of the image forming apparatus 100.
To reverse and eject the sheet S, the reverse unit 37 reverses the sheet S and directs the sheet S to a sheet ejection conveyance passage 39 with the reverse sheet-ejection switching claw, instead of directing the sheet S to the intermediate conveyance passage 43. The sheet S is conveyed along the sheet ejection conveyance passage 39 to the sheet ejection unit 32, which ejects the sheet S from the housing of the image forming apparatus 100.
The sheet S is ejected from the sheet ejection unit 32 onto the first output tray 33 or to a finisher 44 with a sheet ejection switching claw. The sheet S entering the finisher 44 passes through a punch unit 48 that pierces the sheet S. Then, the sheet S temporarily rests on a stack tray 45 for stapling.
After a bunch of sheets S rests on the stack tray 45, a stapler 46 staples the bunch of sheets S. Then, the stapled bunch of sheets S is ejected onto a second output tray 47.
A description is given of advantages of the fixing devices 1 according to the embodiment described above.
A fixing device (e.g., fixing device 1) includes a fixing rotator (e.g., fixing roller 2), a pressure rotator (e.g., pressure roller 3), and a cleaning device (e.g., cleaning web unit 10). The pressure rotator contacts the fixing rotator to form a fixing nip between the fixing rotator and the pressure rotator, through which a recording medium (e.g., sheet S) bearing a toner image is conveyed. The cleaning device cleans a surface of at least one of the fixing rotator and the pressure rotator. The cleaning device includes a cleaning web (e.g., cleaning web 5), a web holder (e.g., web holder 6), a winder (e.g., web roller 7), a cleaning pressure rotator (e.g., cleaning pressure roller 8), a pressure applier (e.g., flat spring 9), and a temporary holder (e.g., temporary holder 90). The cleaning web slides over the at least one of the fixing rotator and the pressure rotator to clean the surface of the at least one of the fixing rotator and the pressure rotator. The web holder holds and sends out the cleaning web. The winder winds the cleaning web. The cleaning pressure rotator presses the cleaning web against the at least one of the fixing rotator and the pressure rotator. The pressure applier presses against the cleaning web along a width direction of the cleaning web perpendicular to a direction in which the cleaning web is wound, thereby preventing the cleaning web from being wrinkled. The temporary holder temporarily holds the pressure applier upon incorporation of the pressure applier into the cleaning device.
According to the embodiments described above, work efficiency is enhanced upon replacement of the cleaning web.
The fixing device 1 incorporating the cleaning web unit 10 described above employs a heating roller system provided with a fixing roller (e.g. fixing roller 2) and a pressure roller (e.g., pressure roller 3). For example, as illustrated in
The component cleaned by the cleaning web device or mechanism (e.g., cleaning web unit 10) according to the embodiment of the present disclosure is not limited to a fixing rotator (e.g., fixing roller 2). Alternatively, the cleaning web device or mechanism may clean a pressure rotator (e.g., pressure roller 3). Alternatively, the cleaning web device or mechanism may clean both the fixing rotator and the pressure rotator.
The image forming apparatus 100 may be a copier, a facsimile machine, a printer, a multifunction peripheral or multifunction printer (MFP) having at least one of copying, printing, scanning, facsimile, and plotter functions, or the like.
Although the present disclosure makes reference to specific embodiments, it is to be noted that the present disclosure is not limited to the details of the embodiments described above and various modifications and enhancements are possible without departing from the scope of the present disclosure. It is therefore to be understood that the present disclosure may be practiced otherwise than as specifically described herein. For example, elements and/or features of different embodiments may be combined with each other and/or substituted for each other within the scope of the present disclosure. The number of constituent elements and their locations, shapes, and so forth are not limited to any of the structure for performing the methodology illustrated in the drawings.
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