1. Field of the Invention
Exemplary aspects of the present invention relate to a fixing device and an image forming apparatus, and more particularly, to a fixing device for fixing a toner image on a recording medium and an image forming apparatus incorporating the fixing device.
2. Description of the Related Art
Related-art image forming apparatuses, such as copiers, facsimile machines, printers, or multifunction printers having at least one of copying, printing, scanning, and facsimile functions, typically form an image on a recording medium according to image data. Thus, for example, a charger uniformly charges a surface of a photoconductor; an optical writer emits a light beam onto the charged surface of the photoconductor to form an electrostatic latent image on the photoconductor according to the image data; a development device supplies toner to the electrostatic latent image formed on the photoconductor to render the electrostatic latent image visible as a toner image; the toner image is directly transferred from the photoconductor onto a recording medium or is indirectly transferred from the photoconductor onto a recording medium 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 on the recording medium, thus forming the image on the recording medium.
Such fixing device is requested to shorten a first print time taken to output the recording medium bearing the toner image onto the outside of the image forming apparatus after the image forming apparatus receives a print job. Additionally, the fixing device is requested to reduce power consumption.
To address these requests, the fixing device may employ a thin endless belt having a decreased thermal capacity and therefore heated quickly by a heater. For example, a pressing roller is pressed against a nip formation assembly disposed inside a loop formed by the endless belt to form a fixing nip between the pressing roller and the endless belt. The heater disposed inside the loop formed by the endless belt heats the endless belt throughout the width in the axial direction thereof. As the pressing roller and the endless belt rotate and convey the recording medium bearing the toner image through the fixing nip, the endless belt and the pressing roller apply heat and pressure to the recording medium, thus fixing the toner image on the recording medium. Since the heater heats the endless belt directly, the endless belt is heated to a predetermined fixing temperature quickly, thus meeting the above-described requests of shortening the first print time and reducing power consumption.
As the recording medium bearing the toner image passes through the fixing nip, it travels over a center of the endless belt in the axial direction thereof. Accordingly, both lateral ends of the endless belt in the axial direction thereof where the recording medium does not travel are subject to damage, for example, thermal damage and mechanical damage.
For example, as the recording medium travels over the center of the endless belt in the axial direction thereof, it draws heat from the center of the endless belt. Conversely, at both lateral ends of the endless belt in the axial direction thereof where the recording medium does not travel, heat is not drawn therefrom to the recording medium. Accordingly, both lateral ends of the endless belt may overheat, resulting in thermal damage of the endless belt.
On the other hand, as the recording medium is discharged from the fixing nip, it may adhere to the endless belt and thereby may not be discharged from the fixing device smoothly. To address this problem, a separator may be disposed opposite the outer circumferential surface of the endless belt at each lateral end of the endless belt in the axial direction thereof. As the recording medium is discharged from the fixing nip, the separator comes into contact with the leading edge of the recording medium, separating the recording medium from the endless belt. However, if the recording medium is accidentally jammed between the endless belt and the separator, a user may pull the jammed recording medium upward to remove it from between the endless belt and the separator. Accordingly, the recording medium pulled upward lifts and spaces the separator apart from the endless belt. However, after the jammed recording medium is removed, the separator no longer lifted by the recording medium may fall and strike the endless belt by resilience of a spring anchored to the separator, thus mechanically deforming or damaging both lateral ends of the endless belt in the axial direction thereof.
This specification describes below an improved fixing device. In one exemplary embodiment of the present invention, the fixing device includes a hollow, endless rotary body rotatable in a predetermined direction of rotation and a pressing body contacting an outer circumferential surface of the endless rotary body to form a fixing nip therebetween through which a first size recording medium bearing a toner image and a second size recording medium bearing a toner image and being greater than the first size recording medium in width in an axial direction of the endless rotary body pass. The first size recording medium passes over a first passage region of the endless rotary body and the second size recording medium passes over a second passage region of the endless rotary body. At least one heater is disposed opposite an inner circumferential surface of the endless rotary body to heat the endless rotary body. A shield is interposed between the endless rotary body and the at least one heater to shield the endless rotary body from heat radiated from the at least one heater. The shield includes a notch disposed opposite a lateral end of the second passage region of the endless rotary body in the axial direction of the endless rotary body. The lateral end of the second passage region overlaps a non-passage region of the endless rotary body in the axial direction thereof where the first size recording medium does not pass.
This specification further describes an improved fixing device. In one exemplary embodiment of the present invention, the fixing device includes a hollow, endless rotary body rotatable in a predetermined direction of rotation and a heater disposed opposite an inner circumferential surface of the endless rotary body to heat the endless rotary body. The pressing body contacts an outer circumferential surface of the endless rotary body to form a fixing nip therebetween through which a recording medium bearing a toner image passes. A separator is disposed opposite the outer circumferential surface of the endless rotary body to contact and separate the recording medium discharged from the fixing nip from the endless rotary body. A belt holder contacts and supports each lateral end of the endless rotary body in an axial direction of the endless rotary body. The belt holder includes a base; a primary projection projecting from the base toward a center of the endless rotary body in the axial direction thereof; and a secondary projection projecting from a part of the primary projection toward the center of the endless rotary body in the axial direction thereof and disposed opposite the separator via the endless rotary body.
This specification further describes an improved image forming apparatus. In one exemplary embodiment of the present invention, the image forming apparatus includes an image carrier and an electrostatic latent image formation device disposed opposite the image carrier to emit light thereto to form an electrostatic latent image thereon. A development device is disposed opposite the image carrier to supply toner to the electrostatic latent image formed thereon to visualize the electrostatic latent image into a toner image. A transfer device is disposed opposite the image carrier to transfer the toner image formed thereon onto a recording medium. The image forming apparatus further includes the fixing device described above that is disposed downstream from the transfer device in a recording medium conveyance direction to fix the toner image on the recording medium.
A more complete appreciation of the invention and the many attendant advantages thereof will be readily obtained as the same becomes better understood by reference to the following detailed description when considered in connection with the accompanying drawings, wherein:
In describing exemplary embodiments illustrated in the drawings, specific terminology is employed for the sake of clarity. However, the disclosure of this 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 operate in a similar manner and achieve a similar result.
Referring now to the drawings, wherein like reference numerals designate identical or corresponding parts throughout the several views, in particular to
As shown in
The image forming devices 2Y, 2C, 2M, and 2K include photoconductive drums 20Y, 20C, 20M, and 20K aligned in the rotation direction R1 of the intermediate transfer belt 11 and serving as a plurality of image carriers that carries the yellow, cyan, magenta, and black toner images, respectively. The visible yellow, cyan, magenta, and black toner images formed on the photoconductive drums 20Y, 20C, 20M, and 20K are primarily transferred onto the intermediate transfer belt 11 that slides over the photoconductive drums 20Y, 20C, 20M, and 20K as it rotates in the rotation direction R1 in a primary transfer process in such a manner that the yellow, cyan, magenta, and black toner images are superimposed on a same position on the intermediate transfer belt 11. Thereafter, the yellow, cyan, magenta, and black toner images superimposed on the intermediate transfer belt 11 are secondarily transferred onto a recording medium P (e.g., a sheet) collectively in a secondary transfer process.
The photoconductive drums 20Y, 20C, 20M, and 20K are surrounded by various devices used to form the yellow, cyan, magenta, and black toner images on the photoconductive drums 20Y, 20C, 20M, and 20K rotating clockwise in
For example, the optical writer 8 is constructed of a semiconductor laser serving as a light source, a coupling lens, an f-θ lens, a troidal lens, reflection mirrors, and a rotatable polygon mirror serving as an optical deflector. The optical writer 8 emits laser beams Lb onto the outer circumferential surface of the respective photoconductive drums 20Y, 20C, 20M, and 20K according to image data sent from an external device such as a client computer, thus forming electrostatic latent images on the photoconductive drums 20Y, 20C, 20M, and 20K, respectively.
Each of the development devices 40Y, 40C, 40M, and 40K, detachably attached to the image forming devices 2Y, 2C, 2M, and 2K, is constructed of a toner supply portion and a development portion. The toner supply portion supplies toner to the development portion that supplies the toner to the electrostatic latent image formed on the respective photoconductive drums 20Y, 20C, 20M, and 20K.
As the intermediate transfer belt 11 rotates in the rotation direction R1, the yellow, cyan, magenta, and black toner images formed on the photoconductive drums 20Y, 20C, 20M, and 20K are primarily transferred onto the intermediate transfer belt 11 in such a manner that the yellow, cyan, magenta, and black toner images are superimposed on the same position on the intermediate transfer belt 11. For example, the photoconductive drums 20Y, 20C, 20M, and 20K are disposed opposite primary transfer rollers 12Y, 12C, 12M, and 12K, serving as primary transferors, respectively, via the intermediate transfer belt 11. As a primary transfer bias is applied to the primary transfer rollers 12Y, 12C, 12M, and 12K, the yellow, cyan, magenta, and black toner images formed on the photoconductive drums 20Y, 20C, 20M, and 20K are primarily transferred onto the intermediate transfer belt 11 successively at different times from the upstream photoconductive drum 20Y to the downstream photoconductive drum 20K in the rotation direction R1 of the intermediate transfer belt 11.
The primary transfer rollers 12Y, 12C, 12M, and 12K sandwich the intermediate transfer belt 11 together with the photoconductive drums 20Y, 20C, 20M, and 20K, forming primary transfer nips between the intermediate transfer belt 11 and the photoconductive drums 20Y, 20C, 20M, and 20K. A power supply connected to the primary transfer rollers 12Y, 12C, 12M, and 12K applies a primary transfer bias, that is, a predetermined direct current voltage and/or an alternating current voltage, to the primary transfer rollers 12Y, 12C, 12M, and 12K.
After the primary transfer of the yellow, cyan, magenta, and black toner images from the photoconductive drums 20Y, 20C, 20M, and 20K, the cleaners 50Y, 50C, 50M, and 50K, each of which is constructed of an elastic rubber band and a toner removal brush, remove residual toner failed to be transferred onto the intermediate transfer belt 11 therefrom.
The photoconductive drums 20Y, 20C, 20M, and 20K are aligned in this order in the rotation direction R1 of the intermediate transfer belt 11. As described above, the photoconductive drums 20Y, 20C, 20M, and 20K are incorporated in the four image forming devices 2Y, 2C, 2M, and 2K that form yellow, cyan, magenta, and black toner images, respectively.
Above the photoconductive drums 20Y, 20C, 20M, and 20K are a transfer belt unit 10, a secondary transfer roller 5 serving as a secondary transferor, and a transfer belt cleaner 13. Below the photoconductive drums 20Y, 20C, 20M, and 20K is the optical writer 8 described above.
In addition to the endless intermediate transfer belt 11 and the plurality of primary transfer rollers 12Y, 12C, 12M, and 12K, the transfer belt unit 10 further includes a driving roller 72 and a driven roller 73 that support the intermediate transfer belt 11 looped thereover. As a driver drives and rotates the driving roller 72 counterclockwise in
The secondary transfer roller 5 contacting the intermediate transfer belt 11 rotates in accordance with rotation of the intermediate transfer belt 11 by friction therebetween. The secondary transfer roller 5 sandwiches the intermediate transfer belt 11 together with the driving roller 72 to form a secondary transfer nip between the secondary transfer roller 5 and the intermediate transfer belt 11. Similar to the primary transfer rollers 12Y, 12C, 12M, and 12K, the secondary transfer roller 5 is connected to the power supply that applies a secondary transfer bias, that is, a predetermined direct current voltage and/or alternating current voltage thereto.
The belt cleaner 13, interposed between the secondary transfer nip and the image forming device 2Y in the rotation direction R1 of the intermediate transfer belt 11, is disposed opposite the driven roller 73 via the intermediate transfer belt 11 and cleans an outer circumferential surface of the intermediate transfer belt 11. The belt cleaner 13 includes a cleaning brush and a cleaning blade that contact the outer circumferential surface of the intermediate transfer belt 11 to remove residual toner from the intermediate transfer belt 11. A waste toner conveyance tube extending from the belt cleaner 13 to an inlet of a waste toner container conveys waste toner collected from the intermediate transfer belt 11 by the belt cleaner 13 to the waste toner container.
Below the transfer device 71 are a paper tray 61, a registration roller pair 4, and a recording medium sensor. The paper tray 61 loads a plurality of recording media P. The registration roller pair 4 feeds a recording medium P sent from the paper tray 61 to the secondary transfer nip. The recording medium sensor detects a leading edge of the recording medium P. For example, the paper tray 61 is situated in a lower portion of the image forming apparatus 1000 and is attached with a feed roller 3 that picks up and feeds an uppermost recording medium P of the plurality of recording media P loaded in the paper tray 61. As the feed roller 3 is driven and rotated counterclockwise in
A conveyance path R extends from the feed roller 3 to an output roller pair 7 to convey the recording medium P picked up from the paper tray 61 onto an outside of the image forming apparatus 1000 through the secondary transfer nip. The conveyance path R is provided with the registration roller pair 4 situated upstream from the secondary transfer nip formed between the secondary transfer roller 5 and the intermediate transfer belt 11 in a recording medium conveyance direction A1 to feed the recording medium P to the secondary transfer nip. For example, the registration roller pair 4 feeds the recording medium P conveyed from the paper tray 61 to the secondary transfer nip at a proper time when the color toner image formed on the intermediate transfer belt 11 by the image forming station 1 as described above reaches the secondary transfer nip. Specifically, when a predetermined time elapses after the recording medium sensor, interposed between the feed roller 3 and the registration roller pair 4, detects the leading edge of the recording medium P conveyed from the feed roller 3, the recording medium P is temporarily halted by the registration roller pair 4 as it strikes the registration roller pair 4. Then, the registration roller pair 4 resumes its rotation at a predetermined time to feed the recording medium P to the secondary transfer nip, for example, at a time when the color toner image formed on the intermediate transfer belt 11 reaches the secondary transfer nip.
The recording media P may be thick paper, postcards, envelopes, plain paper, thin paper, coated paper, art paper, tracing paper, OHP (overhead projector) transparencies, recording sheets, and the like. In addition to the paper tray 61, the image forming apparatus 1000 may be equipped with a bypass tray that loads thick paper, postcards, envelopes, thin paper, tracing paper, OHP transparencies, and the like.
Downstream from the secondary transfer nip in the recording medium conveyance direction A1 are a fixing device 100, the output roller pair 7, and an output tray 17. The fixing device 100 fixes the color toner image transferred from the intermediate transfer belt 11 onto the recording medium P thereon. The output roller pair 7 discharges the recording medium P bearing the fixed color toner image onto the outside of the image forming apparatus 1000, that is, the output tray 17. The output tray 17, disposed atop the image forming apparatus 1000, stocks the recording medium P discharged by the output roller pair 7.
A plurality of toner bottles 9Y, 9C, 9M, and 9K containing yellow, cyan, magenta, and black toners is detachably attached to a plurality of toner bottle holders, respectively, disposed in an upper portion of the image forming apparatus 1000 situated below the output tray 17. A toner supply tube is interposed between the toner bottles 9Y, 9C, 9M, and 9K and the development devices 40Y, 40C, 40M, and 40K, respectively, thus supplying the yellow, cyan, magenta, and black toners from the toner bottles 9Y, 9C, 9M, and 9K to the development devices 40Y, 40C, 40M, and 40K.
As described above, the belt cleaner 13 of the transfer device 71 includes the cleaning brush and the cleaning blade that contact the outer circumferential surface of the intermediate transfer belt 11. The cleaning brush and the cleaning blade scrape and remove a foreign substance such as residual toner off the intermediate transfer belt 11, thus cleaning the intermediate transfer belt 11. The belt cleaner 13 includes a waste toner discharger that discharges the residual toner collected from the intermediate transfer belt 11 into the waste toner conveyance tube described above.
With reference to
As a print job starts, a driver drives and rotates the photoconductive drums 20Y, 20C, 20M, and 20K of the image forming devices 2Y, 2C, 2M, and 2K, respectively, clockwise in
Simultaneously, as the print job starts, the driving roller 72 is driven and rotated counterclockwise in
When the yellow, cyan, magenta, and black toner images formed on the photoconductive drums 20Y, 20C, 20M, and 20K reach the primary transfer nips, respectively, in accordance with rotation of the photoconductive drums 20Y, 20C, 20M, and 20K, the yellow, cyan, magenta, and black toner images are primarily transferred from the photoconductive drums 20Y, 20C, 20M, and 20K onto the intermediate transfer belt 11 by the transfer electric field created at the primary transfer nips in such a manner that the yellow, cyan, magenta, and black toner images are superimposed successively on a same position on the intermediate transfer belt 11. Thus, a color toner image is formed on the intermediate transfer belt 11. After the primary transfer of the yellow, cyan, magenta, and black toner images from the photoconductive drums 20Y, 20C, 20M, and 20K onto the intermediate transfer belt 11, the cleaners 50Y, 50C, 50M, and 50K remove residual toner failed to be transferred onto the intermediate transfer belt 11 and therefore remaining on the photoconductive drums 20Y, 20C, 20M, and 20K therefrom. Thereafter, dischargers discharge the outer circumferential surface of the respective photoconductive drums 20Y, 20C, 20M, and 20K, initializing the surface potential thereof for a next image forming operation.
On the other hand, the feed roller 3 disposed in the lower portion of the image forming apparatus 1000 is driven and rotated to feed a recording medium P from the paper tray 61 toward the registration roller pair 4 in the conveyance path R. The registration roller pair 4 feeds the recording medium P to the secondary transfer nip formed between the secondary transfer roller 5 and the intermediate transfer belt 11 at a time when the color toner image formed on the intermediate transfer belt 11 reaches the secondary transfer nip. The secondary transfer roller 5 is applied with a transfer voltage having a polarity opposite a polarity of the charged yellow, cyan, magenta, and black toners constituting the color toner image formed on the intermediate transfer belt 11, thus creating a predetermined transfer electric field at the secondary transfer nip.
When the color toner image formed on the intermediate transfer belt 11 reaches the secondary transfer nip in accordance with rotation of the intermediate transfer belt 11, the color toner image is secondarily transferred from the intermediate transfer belt 11 onto the recording medium P by the transfer electric field created at the secondary transfer nip. After the secondary transfer of the color toner image from the intermediate transfer belt 11 onto the recording medium P, the belt cleaner 13 removes residual toner failed to be transferred onto the recording medium P and therefore remaining on the intermediate transfer belt 11 therefrom. The removed toner is conveyed and collected into the waste toner container.
Thereafter, the recording medium P bearing the color toner image is conveyed to the fixing device 100 where the color toner image is fixed on the recording medium P. Then, the recording medium P bearing the fixed color toner image is discharged by the output roller pair 7 onto the output tray 17.
The above describes the image forming operation of the image forming apparatus 1000 to form the color toner image on the recording medium P. Alternatively, the image forming apparatus 1000 may form a monochrome toner image by using any one of the four image forming devices 2Y, 2C, 2M, and 2K or may form a bicolor or tricolor toner image by using two or three of the image forming devices 2Y, 2C, 2M, and 2K.
With reference to
A detailed description is now given of a construction of the halogen heater set 123.
The halogen heater set 123 radiates light, that is, radiation heat, to the fixing belt 121, thus heating the fixing belt 121 directly. The halogen heater set 123 includes three halogen heaters 123A, 123B, and 123C disposed inside the loop formed by the fixing belt 121 such that they are disposed opposite an inner circumferential surface of the fixing belt 121. The halogen heaters 123A, 123B, and 123C serve as heaters or heat sources that have three different heating regions thereof in an axial direction of the fixing belt 121 that generate heat, respectively. Accordingly, the three halogen heaters 123A, 123B, and 123C heat the fixing belt 121 in three different regions on the fixing belt 121, respectively, in the axial direction thereof so that the fixing belt 121 heats recording media P of various widths in the axial direction of the fixing belt 121.
For example, the halogen heater 123A serves as a third heater or a center heater that heats a center of the fixing belt 121 in the axial direction thereof where a small recording medium P is conveyed. The center of the fixing belt 121 has a width in the axial direction thereof that is equivalent to a width of a letter size recording medium P in portrait orientation. The halogen heater 123B serves as a first heater or a first lateral end heater that heats each lateral end of the fixing belt 121 in the axial direction thereof where each lateral end of a medium recording medium P in the axial direction of the fixing belt 121 is conveyed. The medium recording medium P is a double letter size recording medium P having a width in portrait orientation greater than that of the letter size recording medium P in the axial direction of the fixing belt 121. The halogen heater 123C serves as a second heater or a second lateral end heater that heats each lateral end of the fixing belt 121 in the axial direction thereof where each lateral end of a large recording medium P in the axial direction of the fixing belt 121 is conveyed. The large recording medium P is an A3 size recording medium P having a width in portrait orientation greater than that of the double letter size recording medium P.
While a small recording medium P having a width in portrait orientation equivalent to or smaller than that of a letter size recording medium P, that is, a letter size recording medium P or smaller, is conveyed through the fixing nip N formed between the fixing belt 121 and the pressing roller 122, the halogen heater 123A is turned on but the halogen heaters 123B and 123C are turned off. While a medium recording medium P in portrait orientation, that is, a double letter size recording medium P, is conveyed through the fixing nip N, the halogen heaters 123A and 123B are turned on. While a large recording medium P in portrait orientation, that is, an A3 size recording medium P, is conveyed through the fixing nip N, the halogen heaters 123A and 123C are turned on.
As shown in
It is to be noted that since the width of a double letter size recording medium P in portrait orientation is equivalent to the width of a letter size recording medium P in landscape orientation in the axial direction of the fixing belt 121 orthogonal to the recording medium conveyance direction A1, the halogen heaters 123A and 123B are turned on to heat the letter size recording medium P in landscape orientation. Similarly, since the width of an A3 size recording medium P in portrait orientation is equivalent to the width of an A4 size recording medium P in landscape orientation in the axial direction of the fixing belt 121, the halogen heaters 123A and 123C are turned on to heat the A4 size recording medium P in landscape orientation.
The portrait orientation defines an orientation in which the long side of the recording medium P is parallel to the recording medium conveyance direction A1. Conversely, the landscape orientation defines an orientation in which the short side of the recording medium P is parallel to the recording medium conveyance direction A1.
As shown in
The fixing device 100 further includes a temperature sensor 127 serving as a temperature detector disposed opposite the outer circumferential surface of the fixing belt 121 and detecting the temperature of the fixing belt 121; a separator 128 disposed opposite the outer circumferential surface of the fixing belt 121 and separating the recording medium P from the fixing belt 121; and a pressurization assembly that presses the pressing roller 122 against the nip formation assembly 124 via the fixing belt 121.
The fixing belt 121 is heated directly by light radiated from the halogen heater set 123 disposed opposite the inner circumferential surface of the fixing belt 121. The nip formation assembly 124 is disposed opposite the inner circumferential surface of the fixing belt 121. As the fixing belt 121 rotates in the rotation direction R3, the inner circumferential surface of the fixing belt 121 slides over the nip formation assembly 124.
As shown in
A detailed description is now given of a construction of the fixing belt 121.
The fixing belt 121 is a thin, flexible endless belt or film. For example, the fixing belt 121 is constructed of a base layer constituting the inner circumferential surface of the fixing belt 121 and a release layer constituting the outer circumferential surface of the fixing belt 121. The base layer is made of metal such as nickel and SUS stainless steel or resin such as polyimide (PI). The release layer is made of tetrafluoroethylene-perfluoroalkylvinylether copolymer (PFA), polytetrafluoroethylene (PTFE), or the like. The release layer prevents adhesion of toner from the recording medium P to the fixing belt 121. Alternatively, an elastic layer, made of rubber such as silicone rubber, silicone rubber foam, and fluoro rubber, may be interposed between the base layer and the release layer. As the fixing belt 121 and the pressing roller 122 exert pressure to a toner image T on a recording medium P, the elastic layer of the pressing roller 122 prevents slight surface asperities of the fixing belt 121 from being transferred onto the toner image T on the recording medium P, thus minimizing variation in gloss of the solid toner image T, that is, minimizing formation of an orange peel image. It is preferable that the elastic layer of the pressing roller 122 has a thickness not smaller than about 100 micrometers, for example, to prevent formation of an orange peel image effectively. As the elastic layer of the pressing roller 122 is deformed by pressure between the pressing roller 122 and the fixing belt 121, the elastic layer absorbs slight surface asperities of the fixing belt 121, preventing formation of an orange peel image.
A detailed description is now given of a construction of the pressing roller 122.
The pressing roller 122 is constructed of a metal core 122a; an elastic layer 122b coating the metal core 122a and made of silicone rubber foam, silicone rubber, fluoro rubber, or the like; and a release layer 122c coating the elastic layer 122b and made of PFA, PTFE, or the like. The pressurization assembly including a spring presses the pressing roller 122 against the nip formation assembly 124 via the fixing belt 121. Thus, the pressing roller 122 pressingly contacting the fixing belt 121 deforms the elastic layer 122b of the pressing roller 122 at the fixing nip N formed between the pressing roller 122 and the fixing belt 121, thus creating the fixing nip N having a predetermined length in the recording medium conveyance direction A1.
A driver (e.g., a motor) disposed inside the image forming apparatus 1000 depicted in
The fixing belt 121 rotates in accordance with rotation of the pressing roller 122. For example, as described above, as the driver such as the motor drives and rotates the pressing roller 122 in the rotation direction R4, a driving force of the driver is transmitted from the pressing roller 122 to the fixing belt 121 at the fixing nip N, thus rotating the fixing belt 121 by friction between the pressing roller 122 and the fixing belt 121. At the fixing nip N, the fixing belt 121 is nipped between the pressing roller 122 and the nip formation assembly 124 and is rotated by friction with the pressing roller 122. Conversely, at a position other than the fixing nip N, the fixing belt 121 is rotated while guided by a belt holder 140 described below at both lateral ends of the fixing belt 121 in the axial direction thereof.
According to this exemplary embodiment, the pressing roller 122 is a solid roller. Alternatively, the pressing roller 122 may be a hollow roller. In this case, a heater such as a halogen heater may be disposed inside the hollow roller. If the pressing roller 122 does not incorporate the elastic layer 122b, the pressing roller 122 has a decreased thermal capacity that improves fixing performance of being heated to a predetermined fixing temperature quickly. However, as the pressing roller 122 and the fixing belt 121 sandwich and press the toner image T on the recording medium P passing through the fixing nip N, slight surface asperities of the fixing belt 121 may be transferred onto the toner image T on the recording medium P, resulting in variation in gloss of the solid toner image T. To address this problem, it is preferable that the pressing roller 122 incorporates the elastic layer 122b having a thickness not smaller than about 100 micrometers. The elastic layer 122b having the thickness not smaller than about 100 micrometers elastically deforms to absorb slight surface asperities of the fixing belt 121, preventing variation in gloss of the toner image T on the recording medium P.
The elastic layer 122b of the pressing roller 122 is made of solid rubber. Alternatively, if no heater is disposed inside the pressing roller 122, the elastic layer 122b may be made of insulative rubber, such as sponge rubber. The insulative rubber such as sponge rubber is more preferable than the solid rubber because it has an increased insulation that draws less heat from the fixing belt 121. According to this exemplary embodiment, the pressing roller 122 is pressed against the fixing belt 121. Alternatively, the pressing roller 122 may merely contact the fixing belt 121 with no pressure therebetween.
A detailed description is now given of a configuration of the halogen heater set 123.
Both lateral ends of the halogen heater set 123 in a longitudinal direction thereof parallel to the axial direction of the fixing belt 121 are mounted on side plates of the fixing device 100, respectively. A power supply situated inside the image forming apparatus 1000 supplies power to the halogen heater set 123 so that the halogen heater set 123 heats the fixing belt 121. A controller 200, that is, a central processing unit (CPU), provided with a random-access memory (RAM) and a read-only memory (ROM), for example, operatively connected to the halogen heater set 123 and the temperature sensor 127 controls the halogen heater set 123, that is, turns on and off the halogen heater set 123 or adjusts an amount of power supplied to the halogen heater set 123 based on the temperature of the fixing belt 121 detected by the temperature sensor 127 so as to adjust the temperature of the fixing belt 121 to a desired fixing temperature. Alternatively, an induction heater, a resistance heat generator, a carbon heater, or the like may be employed as a heater to heat the fixing belt 121 instead of the halogen heater set 123.
A detailed description is now given of a construction of the nip formation assembly 124.
The nip formation assembly 124 includes a base pad 131 and a slide sheet 130 (e.g., a low friction sheet) covering an outer surface of the base pad 131. A longitudinal direction of the base pad 131 in which it extends is parallel to the axial direction of the fixing belt 121 or the pressing roller 122. The base pad 131 receives pressure from the pressing roller 122 to define the shape of the fixing nip N.
The base pad 131 of the nip formation assembly 124 is mounted on and supported by the stay 125. Accordingly, even if the base pad 131 receives pressure from the pressing roller 122, the base pad 131 is not bent by the pressure and therefore produces a uniform nip width throughout the entire width of the pressing roller 122 in the axial direction thereof. The base pad 131 is made of a heat-resistant material having heat resistance against temperatures up to about 200 degrees centigrade. Accordingly, even if the base pad 131 is heated to a predetermined fixing temperature range, the base pad 131 is not thermally deformed, thus retaining the desired shape of the fixing nip N stably and thereby maintaining the quality of the fixed toner image T on the recording medium P. For example, the base pad 131 is made of general heat-resistant resin such as polyether sulfone (PES), polyphenylene sulfide (PPS), liquid crystal polymer (LCP), polyether nitrile (PEN), polyamide imide (PAI), polyether ether ketone (PEEK), or the like.
The slide sheet 130 is interposed at least between the base pad 131 and the fixing belt 121. For example, the slide sheet 130 covers at least the opposed face 124a of the base pad 131 disposed opposite the fixing belt 121 at the fixing nip N. As the fixing belt 121 rotates in the rotation direction R3, it slides over the slide sheet 130, decreasing a driving torque exerted on the fixing belt 121. Accordingly, a decreased friction is imposed onto the fixing belt 121 from the nip formation assembly 124. According to this exemplary embodiment, the fixing belt 121 slides over the base pad 131 indirectly via the slide sheet 130. Alternatively, the nip formation assembly 124 may not incorporate the slide sheet 130 so that the fixing belt 121 slides over the base pad 131 directly.
The stay 125 is made of metal having an increased mechanical strength, such as stainless steel and iron, to support the nip formation assembly 124 against pressure from the pressing roller 122, preventing bending of the nip formation assembly 124. The base pad 131 is also made of a rigid material having an increased mechanical strength. For example, the base pad 131 is made of resin such as LCP, metal, ceramic, or the like.
A detailed description is now given of a configuration of the reflector 126.
The reflector 126 is interposed between the stay 125 and the halogen heater set 123. According to this exemplary embodiment, the reflector 126 is mounted on the stay 125. For example, the reflector 126 is made of aluminum, stainless steel, or the like. The reflector 126 has a reflection face 126a that reflects light, that is, radiation heat, radiated from the halogen heater set 123 thereto toward the fixing belt 121. Accordingly, the fixing belt 121 receives an increased amount of light from the halogen heater set 123 and thereby is heated efficiently. Additionally, the reflector 126 minimizes transmission of light from the halogen heater set 123 to the stay 125, thus minimizing energy wasted in unnecessarily heating the stay 125 by light from the halogen heater set 123 and thereby saving energy. Instead of mounting the reflector 126, a surface of the stay 125 may be treated with insulation or mirror finished to attain the advantages described above.
The fixing device 100 according to this exemplary embodiment attains various improvements to save more energy and shorten a first print time taken to output a recording medium P bearing a fixed toner image T onto the outside of the image forming apparatus 1000 depicted in
As a second improvement, the fixing belt 121 is designed to be thin and have a reduced loop diameter so as to decrease the thermal capacity thereof. For example, the fixing belt 121 is constructed of the base layer having a thickness in a range of from about 20 micrometers to about 50 micrometers; the elastic layer having a thickness in a range of from about 100 micrometers to about 300 micrometers; and the release layer having a thickness in a range of from about 10 micrometers to about 50 micrometers. Thus, the fixing belt 121 has a total thickness not greater than about 1 mm. The loop diameter of the fixing belt 121 is in a range of from about 20 mm to about 40 mm. In order to decrease the thermal capacity of the fixing belt 121 further, the fixing belt 121 may have a total thickness not greater than about 0.20 mm, preferably not greater than about 0.16 mm. Additionally, the loop diameter of the fixing belt 121 may be not greater than about 30 mm.
According to this exemplary embodiment, the pressing roller 122 has a diameter in a range of from about 20 mm to about 40 mm so that the loop diameter of the fixing belt 121 is equivalent to the diameter of the pressing roller 122. However, the loop diameter of the fixing belt 121 and the diameter of the pressing roller 122 are not limited to the above. For example, the loop diameter of the fixing belt 121 may be smaller than the diameter of the pressing roller 122. In this case, a curvature of the fixing belt 121 at the fixing nip N is greater than that of the pressing roller 122, facilitating separation of the recording medium P discharged from the fixing nip N from the fixing belt 121.
Since the fixing belt 121 has a reduced loop diameter, space inside the loop formed by the fixing belt 121 is small. To address this circumstance, both ends of the stay 125 in the recording medium conveyance direction A1 are folded into a square bracket that accommodates the halogen heater set 123. Thus, the stay 125 and the halogen heater set 123 are placed in the small space inside the loop formed by the fixing belt 121.
With reference to
As shown in
As shown in
A slip ring is interposed between a lateral edge of the fixing belt 121 and an inward face of the belt holder 140 disposed opposite the lateral edge of the fixing belt 121 in the axial direction thereof. The slip ring serves as a protector that protects the lateral edge of the fixing belt 121 in the axial direction thereof. For example, even if the fixing belt 121 is skewed in the axial direction thereof, the slip ring prevents the lateral edge of the fixing belt 121 from coming into direct contact with the belt holder 140, thus minimizing abrasion and breakage of the lateral edge of the fixing belt 121 in the axial direction thereof. Since an inner diameter of the slip ring is sufficiently greater than an outer diameter of the belt holder 140, the slip ring loosely slips on the belt holder 140. Accordingly, when the lateral edge of the fixing belt 121 comes into contact with the slip ring, the slip ring is rotatable in accordance with rotation of the fixing belt 121 by friction therebetween. Alternatively, the slip ring may remain at rest irrespective of rotation of the fixing belt 121. The slip ring is made of heat-resistant, super engineering plastics such as PEEK, PPS, PAI, and PTFE.
With reference to
As shown in
Hence, the upstream portion 131a of the base pad 131 of the nip formation assembly 124 is not interposed between the inner circumferential surface of the fixing belt 121 and an upstream curve 125d1 of the stay 125 in the diametrical direction of the fixing belt 121. Similarly, the downstream portion 131b of the base pad 131 of the nip formation assembly 124 is not interposed between the inner circumferential surface of the fixing belt 121 and a downstream curve 125d2 of the stay 125 in the diametrical direction of the fixing belt 121. Accordingly, the upstream curve 125d1 and the downstream curve 125d2 of the stay 125 are situated in proximity to the inner circumferential surface of the fixing belt 121. Consequently, the stay 125 having an increased size that enhances the mechanical strength thereof is accommodated in the limited space inside the loop formed by the fixing belt 121. As a result, the stay 125, with its enhanced mechanical strength, supports the nip formation assembly 124 properly, preventing bending of the nip formation assembly 124 caused by pressure from the pressing roller 122 and thereby improving fixing performance.
As shown in
Additionally, as the upstream arm 125b1 and the downstream arm 125b2 elongate further in the pressurization direction D1 of the pressing roller 122, the mechanical strength of the stay 125 becomes greater. Accordingly, it is preferable that a front edge 125c of each of the upstream arm 125b1 and the downstream arm 125b2 is situated as close as possible to the inner circumferential surface of the fixing belt 121 to allow the upstream arm 125b1 and the downstream arm 125b2 to project longer from the base 125a in the pressurization direction D1 of the pressing roller 122. However, since the fixing belt 121 swings or vibrates as it rotates, if the front edge 125c of each of the upstream arm 125b1 and the downstream arm 125b2 is excessively close to the inner circumferential surface of the fixing belt 121, the swinging or vibrating fixing belt 121 may come into contact with the upstream arm 125b1 or the downstream arm 125b2. For example, if the thin fixing belt 121 is used as in this exemplary embodiment, the thin fixing belt 121 swings or vibrates substantially. Accordingly, it is necessary to position the front edge 125c of each of the upstream arm 125b1 and the downstream arm 125b2 with respect to the fixing belt 121 carefully.
Specifically, as shown in
The front edge 125c of each of the upstream arm 125b1 and the downstream arm 125b2 situated as close as possible to the inner circumferential surface of the fixing belt 121 allows the upstream arm 125b1 and the downstream arm 125b2 to project longer from the base 125a in the pressurization direction D1 of the pressing roller 122. Accordingly, even if the fixing belt 121 has a decreased loop diameter, the stay 125 having the longer upstream arm 125b1 and the longer downstream arm 125b2 attains an enhanced mechanical strength.
With reference to
As the image forming apparatus 1000 depicted in
A recording medium P bearing a toner image T formed by the image forming operation of the image forming apparatus 1000 described above is conveyed in the recording medium conveyance direction A1 while guided by a guide plate and enters the fixing nip N formed between the pressing roller 122 and the fixing belt 121 pressed by the pressing roller 122. The fixing belt 121 heated by the halogen heater set 123 heats the recording medium P and at the same time the pressing roller 122 pressed against the fixing belt 121 and the fixing belt 121 together exert pressure to the recording medium P, thus fixing the toner image T on the recording medium P.
The recording medium P bearing the fixed toner image T is discharged from the fixing nip N in a recording medium conveyance direction A2. As a leading edge of the recording medium P comes into contact with a front edge of the separator 128, the separator 128 separates the recording medium P from the fixing belt 121. Thereafter, the separated recording medium P is discharged by the output roller pair 7 depicted in
With reference to
The nip formation assembly 124 guides the fixing belt 121 to the fixing nip N, minimizing vibration or swinging of the fixing belt 121 before the fixing belt 121 enters the fixing nip N and thereby facilitating stable and smooth entry of the fixing belt 121 into the fixing nip N. Accordingly, even if no guide other than the nip formation assembly 124 is configured to guide a center interposed between both lateral ends of the fixing belt 121 in the axial direction thereof to the fixing nip N, the nip formation assembly 124 guides and rotates the fixing belt 121 stably and smoothly. Consequently, the nip formation assembly 124 minimizes load imposed on the rotating fixing belt 121 and resultant wear of the fixing belt 121, preventing damage and breakage of the fixing belt 121 and enhancing reliability of the fixing device 100. For example, it is difficult for the fixing belt 121 having a reduced thickness that decreases the thermal capacity thereof to have an increased mechanical strength. However, the nip formation assembly 124 supports and guides the thin fixing belt 121, preventing damage and breakage of the fixing belt 121.
The nip formation assembly 124 incorporated in the fixing device 100 depicted in
Since the nip formation assembly 124 serves as a guide that guides the fixing belt 121 to the fixing nip N, it is not necessary to provide a guide separately from the nip formation assembly 124. Hence, no component is interposed between the inner circumferential surface of the fixing belt 121 and the upstream curve 125d1 of the stay 125 in the diametrical direction of the fixing belt 121. Similarly, no component is interposed between the inner circumferential surface of the fixing belt 121 and the downstream curve 125d2 of the stay 125 in the diametrical direction of the fixing belt 121. That is, the upstream curve 125d1 and the downstream curve 125d2 of the stay 125 are disposed opposite the inner circumferential surface of the fixing belt 121 directly. Accordingly, the upstream curve 125d1 and the downstream curve 125d2 of the stay 125 are situated in proximity to the inner circumferential surface of the fixing belt 121. Consequently, the stay 125 having an increased size that enhances the mechanical strength thereof is accommodated in the limited space inside the loop formed by the fixing belt 121. As a result, even if the fixing belt 121 is downsized to decrease its thermal capacity, the stay 125 accommodated inside the downsized fixing belt 121 achieves an enhanced mechanical strength that supports the nip formation assembly 124 properly, preventing bending of the nip formation assembly 124 caused by pressure from the pressing roller 122 and thereby improving fixing performance.
While the pressing roller 122 is isolated from the fixing belt 121, the nip formation assembly 124 is spaced apart from the inner circumferential surface of the fixing belt 121 so that the upstream portion 131a and the downstream portion 131b of the base pad 131 of the nip formation assembly 124 do not pressingly contact the fixing belt 121. Accordingly, the fixing belt 121 does not slide over the nip formation assembly 124, minimizing load imposed on the fixing belt 121 and resultant abrasion of the fixing belt 121. Additionally, the fixing belt 121 contacts the nip formation assembly 124 with a reduced friction therebetween, producing a desired path through which the fixing belt 21 enters the fixing nip N.
With reference to
The engine control unit 200b is operatively connected to the temperature sensor 127, the halogen heater set 123, and a pressing roller driver 129 incorporated in the fixing device 100. The engine control unit 200b including the CPU, the ROM, and the RAM, by executing a preloaded control program, controls a printer engine including the plurality of image forming devices 2Y, 2C, 2M, and 2K, the optical writer 8, and the fixing device 100 depicted in
The image forming apparatus 1000 has three modes: the image forming mode to perform the image forming processes described above; a standby mode to wait for an instruction to start the image forming processes; and a sleep mode to consume less power than the standby mode. For example, in the image forming mode, the fixing belt 121 of the fixing device 100 is warmed up to a predetermined fixing temperature in a range of from about 158 degrees centigrade to about 170 degrees centigrade, and then the fixing device 100 performs the fixing process for fixing the toner image T on the recording medium P. In the standby mode, the fixing belt 121 of the fixing device 100 is maintained at a predetermined lower temperature of about 90 degrees centigrade lower than the predetermined fixing temperature set in the image forming mode. In the sleep mode, power is not supplied to the engine control unit 200b and the printer engine including the fixing device 100, and thus the halogen heater set 123 and the pressing roller 122 are turned off.
With reference to
As shown in
Similarly, the outboard lateral end 123Ca of the halogen heater 123C in the axial direction of the fixing belt 121 is disposed opposite a non-passage region NP2 of the fixing belt 121 where an A3 size recording medium in portrait orientation (hereinafter referred to as an A3 size recording medium A3T) does not pass. Accordingly, after a plurality of A3 size recording media A3T passes over the fixing belt 121 continuously while the halogen heater 123C is turned on, the non-passage region NP2 of the fixing belt 121 may overheat because the plurality of A3 size recording media A3T does not pass over the non-passage region NP2 of the fixing belt 121 and therefore does not draw heat therefrom. To address this problem, the shield 133 shields the non-passage region NP2 of the fixing belt 121 from light radiated from the halogen heater 123C, thus decreasing an amount of light radiated from the halogen heater 123C that reaches the non-passage region NP2 of the fixing belt 121.
Hence, the shield 133 shields the non-passage regions NP1 and NP2 of the fixing belt 121 from light radiated from the halogen heaters 123B and 123C, minimizing overheating of the non-passage regions NP1 and NP2 of the fixing belt 121 after the plurality of double letter size recording media DLT and the plurality of A3 size recording media A3T continuously pass over the fixing belt 121, respectively, and thereby preventing wear and damage of the fixing belt 121 caused by heat from the halogen heaters 123B and 123C.
The shield 133 is made of a heat-resistant material having resistance against temperatures up to about 400 degrees centigrade. According to this exemplary embodiment, the shield 133 is a metal sheet made of SUS stainless steel and having a thickness of about 0.5 mm. Thus, even if the shield 133 is heated by light from the halogen heaters 123B and 123C, the heat-resistant shield 133 minimizes its wear that may arise due to overheating.
An opposed face 133c depicted in
As shown in
If the shield 133 shields the entire outboard lateral end 123Ba of the halogen heater 123B disposed opposite the non-passage region NP1 of the fixing belt 121 depicted in
To address this problem, the shield 133 has a shape that reduces overheating of the non-passage region NP1 of the double letter size recording medium DLT and the non-passage region NP2 of the A3 size recording medium A3T and at the same time minimizes fixing failure at the lateral end P2e of the passage region P2 where the A3 size recording medium A3T passes that may arise due to insufficient heating. For example, as shown in
With reference to
As shown in
As shown in
With the configuration described above, the fixing device 100 reduces overheating of the non-passage region NP1 of the fixing belt 121 where the double letter size recording medium DLT does not pass and the non-passage region NP2 of the fixing belt 121 where the A3 size recording medium A3T does not pass. Simultaneously, the fixing device 100 minimizes fixing failure that may arise due to decreased temperature at the lateral end P2e of the passage region P2 of the fixing belt 121 where the A3 size recording medium A3T passes, which is disposed at both lateral ends of the fixing belt 121 in the axial direction thereof.
With reference to
As shown in
Accordingly, the shield 133 reduces overheating of the non-passage region NP1 of the fixing belt 121 where the first size recording medium does not pass and the non-passage region NP2 of the fixing belt 121 where the second size recording medium does not pass. Simultaneously, the shield 133 prevents temperature decrease in the lateral end P2e of the passage region P2 of the fixing belt 121 where the second size recording medium passes, thus minimizing fixing failure that may arise due to the decreased temperature of the fixing belt 121.
As shown in
As shown in
As shown in
As shown in
As shown in
The shield 133 has resistance against temperatures up to about 400 degrees centigrade. Accordingly, the shield 133 minimizes thermal wear of itself due to temperature increase.
As shown in
As shown in
The present invention is not limited to the details of the exemplary embodiments described above, and various modifications and improvements are possible. For example, as shown in
As shown in
For example, the notch 133a of the shield 133 disposed opposite the lateral end P2e of the passage region P2 of the fixing belt 121 where the second size recording medium passes, which overlaps the non-passage region NP1 of the fixing belt 121 where the first size recording medium does not pass in the axial direction thereof, allows heat from the halogen heaters 123B and 123C to reach the fixing belt 121. Accordingly, as shown in
According to the exemplary embodiments described above, the shield 133 having the notch 133a is employed in the fixing device 100 incorporating the plurality of halogen heaters 123A, 123B, and 123C. Alternatively, the shield 133 may be employed in a fixing device 100S incorporating a single halogen heater 123H as shown in
With reference to
Similarly, an outboard lateral end 123Ha of the halogen heater 123H in the axial direction of the fixing belt 121 is disposed opposite the non-passage region NP2 of the fixing belt 121 where the A3 size recording medium A3T in portrait orientation does not pass. Accordingly, after the plurality of A3 size recording media A3T passes over the fixing belt 121 continuously while the halogen heater 123H is turned on, the non-passage region NP2 of the fixing belt 121 may overheat because the plurality of A3 size recording media A3T does not pass over the non-passage region NP2 of the fixing belt 121 and therefore does not draw heat therefrom. To address this problem, the shield 133 shields the non-passage region NP2 of the fixing belt 121 from light radiated from the halogen heater 123H, thus decreasing an amount of light radiated from the halogen heater 123H that reaches the non-passage region NP2 of the fixing belt 121.
Hence, the shield 133 shields the non-passage regions NP1 and NP2 of the fixing belt 121 from light radiated from the halogen heater 123H, minimizing overheating of the non-passage regions NP1 and NP2 of the fixing belt 121 after the plurality of double letter size recording media DLT and the plurality of A3 size recording media A3T continuously pass over the fixing belt 121, respectively, and thereby preventing wear and damage of the fixing belt 121 caused by heat from the halogen heater 123H.
However, if the shield 133 is configured to shield the entire non-passage region NP1 of the fixing belt 121 where the double letter size recording medium DLT does not pass, during passage of the double letter size recording medium DLT, the shield 133 may also prevent light radiated from the halogen heater 123H from reaching the fixing belt 121 unnecessarily. Accordingly, such shield 133 may unnecessarily restrict heating of an area on the fixing belt 121 that need to be heated by the halogen heater 123H. For example, the lateral end P2e of the passage region P2 of the fixing belt 121 in the axial direction thereof where the A3 size recording medium A3T passes may not be heated by the halogen heater 123H to the predetermined fixing temperature, resulting in fixing failure.
To address this problem, the shield 133 has the shape that reduces overheating of the non-passage region NP1 of the double letter size recording medium DLT and the non-passage region NP2 of the A3 size recording medium A3T and at the same time minimizes fixing failure at the lateral end P2e of the passage region P2 of the A3 size recording medium A3T that may arise due to insufficient heating. For example, as shown in
According to the exemplary embodiments described above, the heaters (e.g., the halogen heaters 123A, 123B, and 123C depicted in
With reference to
The fixing device 100T further includes a cabinet 31 housing the components of the fixing device 100T described above; a plurality of bolts 32 that bolts the belt holder 28 to the cabinet 31; the temperature sensor 127; and the controller 200 operatively connected to the temperature sensor 127 and the heater 23 to control the heater 23 based on the temperature of the fixing belt 21 detected by the temperature sensor 127. The fixing device 100T is detachably installed inside the body 2 of the image forming apparatus 1000 depicted in
As a recording medium P bearing a toner image T is conveyed through the fixing nip N formed between the fixing belt 21 and the pressing roller 22, the fixing belt 21 heated by the heater 23 and the pressing roller 22 apply heat and pressure to the recording medium P, thus fixing the toner image T on the recording medium P. As the recording medium P bearing the fixed toner image T is discharged from the fixing nip N, the separator 27 separates the recording medium P from the fixing belt 21. Thereafter, the recording medium P is conveyed through the conveyance path R to the output roller pair 7 depicted in
With reference to
Alternatively, the fixing belt 21 may not incorporate the elastic layer 21b. In this case, the fixing belt 21 has a reduced thermal capacity that facilitates heating of the fixing belt 21 by the heater 23 and thereby saving energy. Further, the loop diameter of the fixing belt 21 may be in a range of from about 15 mm to about 120 mm according to settings of the fixing device 100T. As shown in
As shown in
The elastic layer 21b of the fixing belt 21 is made of rubber such as silicone rubber (Q) and fluoro rubber (FKM) and has a thickness in a range of from about 20 micrometers to about 900 micrometers. The elastic layer 21b absorbs surface asperities of the fixing belt 21 and the recording medium P. Accordingly, as the fixing belt 21 and the pressing roller 22 apply heat and pressure to the recording medium P conveyed through the fixing nip N, the elastic layer 21b, by absorbing surface asperities of the fixing belt 21 and the recording medium P, facilitates uniform application of heat and pressure to the recording medium P. As the fixing belt 21 and the pressing roller 22 exert pressure to the toner image T on the recording medium P to fix the toner image T on the recording medium P, slight surface asperities of the fixing belt 21 may be transferred onto the toner image T on the recording medium P, producing variation in gloss on the solid toner image T that results in formation of an orange peel image. To address this problem, the elastic layer 21b of the fixing belt 21 having a thickness not smaller than about 100 micrometers deforms and absorbs slight surface asperities of the fixing belt 21, thus minimizing variation in gloss of the solid toner image T, that is, minimizing formation of an orange peel image.
The release layer 21c of the fixing belt 21 is made of a material that facilitates separation of the recording medium P and the toner image T formed thereon from the fixing belt 21, that is, a material that prevents adhesion and sticking of toner of the toner image T to the fixing belt 21 and is used on a surface of a die, for example. For example, the release layer 21c is made of resin such as PFA, PTFE, polyether imide (PEI), and PES and has a thickness in a range of from about 1 micrometer to about 200 micrometers.
With reference to
As shown in
The metal core 22a, that is, a solid tube having a desired mechanical strength, is made of thermally conductive metal such as carbon steel (e.g., SC and STKM) and aluminum (Al). Alternatively, the metal core 22a may be a hollow tube accommodating a heater such as a halogen heater that heats the recording medium P conveyed through the fixing nip N via the metal core 22a, the elastic layer 22b, and the release layer 22c.
Similar to the elastic layer 21b of the fixing belt 21 described above, the elastic layer 22b of the pressing roller 22 is made of synthetic rubber such as silicone rubber (Q) and fluoro rubber (FKM). The synthetic rubber is relatively rigid, non-foaming solid rubber. If no heater is situated inside the metal core 22a, the elastic layer 22b may be made of foaming synthetic rubber such as sponge rubber. The sponge rubber, as it contains foam, provides an increased insulation that insulates the pressing roller 22 from the fixing belt 21 heated by the heater 23. Hence, heat is not drawn from the fixing belt 21 to the pressing roller 22, saving energy.
Like the release layer 21c of the fixing belt 21, the release layer 22c of the pressing roller 22 is made of a thermally conductive, durable material that facilitates separation of the recording medium P from the pressing roller 22 and enhances durability of the elastic layer 22b. For example, the release layer 22c is produced by coating of the elastic layer 22b with PFA or fluoroplastic coating made of PFA or PTFE. Alternatively, the release layer 22c may be a silicone rubber layer or a fluoro rubber layer.
With reference to
The heater 23 mounted on the cabinet 31 is situated inside the loop formed by the fixing belt 21 and spaced apart from an inner circumferential surface of the fixing belt 21. The heater 23 has a single light emission region that generates radiation heat to heat the fixing belt 21 directly. The heater 23 is a radiant heater such as a halogen heater incorporating a halogen lamp that generates radiation heat, a carbon heater incorporating a quartz tube filled with carbon fiber in inert gas, and a ceramic heater including resistance wiring embedded inside ceramic. The controller 200 controls powering on and off of the heater 23.
With reference to
As shown in
With reference to
As shown in
The contact face portion 25a has a plane disposed opposite the pressing roller 22 via the fixing belt 21. As the pressing roller 22 presses the fixing belt 21 against the nip formation assembly 25, the fixing belt 21 comes into contact with the plane of the contact face portion 25a of the nip formation assembly 25. Simultaneously, as the pressing roller 22 presses the fixing belt 21 against the nip formation assembly 25, the elastic layer 22b depicted in
According to this exemplary embodiment, the contact face portion 25a of the nip formation assembly 25 has the plane as described above. Alternatively, the contact face portion 25a may have other shapes. For example, the contact face portion 25a may have a concave curve with respect to the fixing belt 21 that corresponds to a circumference of the pressing roller 22. The concave curve of the contact face portion 25a directs a leading edge of the recording medium P discharged from the fixing nip N toward the pressing roller 22, thus facilitating separation of the recording medium P from the fixing belt 21 and thereby preventing jamming of the recording medium P conveyed through the fixing device 100T.
With reference to
As shown in
As shown in
With reference to
It is to be noted that the fixing belt 21 is not illustrated in
With reference to
The flange 51 is constructed of a planar plate 51d and through-holes 51a and 52b produced through the plate 51d and used to attach the flange 51 to the cabinet 31 depicted in
The base 52 is formed into a ring or a tube projecting from the flange 51 toward a center of the fixing belt 21 in the axial direction thereof. As shown in
The primary projection 53 is formed into a ring or a tube projecting from the base 52 toward the center of the fixing belt 21 in the axial direction thereof. Since the primary projection 53, disposed opposite the inner circumferential surface of the fixing belt 21, contacts and supports the fixing belt 21 at each lateral end in the axial direction thereof, the primary projection 53 serves as an endless rotary body guide that guides the fixing belt 21 as it rotates in the rotation direction R3. As shown in
As shown in
As shown in
The secondary projection 54 has a friction coefficient different from that of the primary projection 53. For example, a coefficient of static friction and a coefficient of kinetic friction of the secondary projection 54 are smaller than those of the primary projection 53, respectively. The friction coefficient of the secondary projection 54 may be smaller than that of the primary projection 53 by coating an outer circumferential face 54a of the secondary projection 54, disposed opposite the positioning portion 41c of the separation plate 41 of the separator 27 via the fixing belt 21, with fluoroplastic (e.g., fluorocarbon polymers).
Alternatively, the outer circumferential face 54a of the secondary projection 54 may be made of a material having a friction coefficient smaller than that of the primary projection 53, thus rendering the friction coefficient of the secondary projection 54 to be smaller than that of the primary projection 53. Yet alternatively, a piece made of a material having a friction coefficient smaller than that of the primary projection 53 may be embedded in or attached to the outer circumferential face 54a of the secondary projection 54.
With reference to
As shown in
With reference to
As shown in
With reference to
As shown in
To address this problem, the fixing device 100T includes the secondary projection 54 of the belt holder 28 that is disposed opposite the positioning portion 41c of the separator 27 via the fixing belt 21 as shown in
With reference to
As shown in
As shown in
The secondary projection 54 of the belt holder 28 and the positioning portion 41c of the separator 27 prevent buckling and plastic deformation of the fixing belt 21. For example, as shown in
To address this problem, the secondary projection 54 of the belt holder 28 is disposed opposite the positioning portion 41c of the separator 27. Accordingly, even if the separator 27 strikes the fixing belt 21, the secondary projection 54 supporting the fixing belt 21 absorbs impact exerted from the separator 27 onto the fixing belt 21. Consequently, the secondary projection 54 of the belt holder 28 prevents damages, that is, buckling and plastic deformation, of the fixing belt 21.
As shown in
As shown in
As shown in
Even if a front face 26f of the support 26 disposed opposite the heater 23 is configured to be mirror finished by coating or attaching of a reflection material, instead of attaching the reflector 24 to the support 26, the support 26 prohibits heat radiated from the heater 23 from being conducted to the secondary projection 54 directly. Hence, durability of the belt holder 28 improves.
For example, the coefficient of static friction and the coefficient of kinetic friction of the secondary projection 54 are smaller than those of the primary projection 53, respectively, by coating the secondary projection 54 with fluoroplastic or using a material for the secondary projection 54 that is different from a material used for other components. Accordingly, even if a fixing belt that differs from the fixing belt 21 in design specification is installed in the fixing device 100T and the fixing belt 21 receives a force that may twist or warp the fixing belt 21 as the fixing belt 21 slides over the secondary projection 54, the coefficient of static friction and the coefficient of kinetic friction of the secondary projection 54 that are smaller than those of the components other than the secondary projection 54, for example, the primary projection 53, prevent the fixing belt 21 from being twisted and warped. Consequently, the fixing belt 21 rotates smoothly, improving its durability.
Further, even if the fixing belt 21 comes into contact with the secondary projection 54, the coefficient of static friction and the coefficient of kinetic friction of the secondary projection 54 that are smaller than those of the components other than the secondary projection 54 decrease resistance between the rotating fixing belt 21 and the secondary projection 54, minimizing torque required to rotate the fixing belt 21.
The fixing device 100T is installable in the image forming apparatus 1000 depicted in
The fixing device 100T depicted in
With reference to
As shown in
According to the exemplary embodiments described above, the pressing rollers 122 and 22 serve as a pressing body disposed opposite the fixing belts 121 and 21, respectively. Alternatively, a pressing belt, a pressing plate, a pressing pad, or the like may serve as a pressing body.
The present invention has been described above with reference to specific exemplary embodiments. Note that the present invention is not limited to the details of the embodiments described above, but various modifications and enhancements are possible without departing from the spirit and scope of the invention. It is therefore to be understood that the present invention may be practiced otherwise than as specifically described herein. For example, elements and/or features of different illustrative exemplary embodiments may be combined with each other and/or substituted for each other within the scope of the present invention.
Number | Date | Country | Kind |
---|---|---|---|
2012-026628 | Feb 2012 | JP | national |
2012-262077 | Nov 2012 | JP | national |
This patent application is a divisional of U.S. patent application Ser. No. 13/746,871 filed Jan. 22, 2013, which is based on and claims priority pursuant to 35 U.S.C. §119 to Japanese Patent Applications No. 2012-026628 filed Feb. 9, 2012, and No. 2012-262077 filed on Nov. 30, 2012, in the Japanese Patent Office, the entire disclosures of each of which are hereby incorporated by reference herein.
Number | Name | Date | Kind |
---|---|---|---|
7088931 | Kojima | Aug 2006 | B2 |
7437113 | Suzuki et al. | Oct 2008 | B2 |
7773931 | Jung et al. | Aug 2010 | B2 |
7842906 | Takematsu et al. | Nov 2010 | B2 |
8351807 | Seki | Jan 2013 | B2 |
20060029411 | Ishii et al. | Feb 2006 | A1 |
20070212089 | Seo et al. | Sep 2007 | A1 |
20070242988 | Seo et al. | Oct 2007 | A1 |
20070280754 | Ogawa et al. | Dec 2007 | A1 |
20070292175 | Shinshi | Dec 2007 | A1 |
20080025772 | Seo et al. | Jan 2008 | A1 |
20080025773 | Ito et al. | Jan 2008 | A1 |
20080219721 | Ito et al. | Sep 2008 | A1 |
20080226326 | Seo et al. | Sep 2008 | A1 |
20080232873 | Ueno et al. | Sep 2008 | A1 |
20080298862 | Shinshi | Dec 2008 | A1 |
20090110451 | Jung et al. | Apr 2009 | A1 |
20090116884 | Nonaka et al. | May 2009 | A1 |
20090123201 | Ehara et al. | May 2009 | A1 |
20090148205 | Seo et al. | Jun 2009 | A1 |
20090245865 | Shinshi et al. | Oct 2009 | A1 |
20090245897 | Seo et al. | Oct 2009 | A1 |
20090297197 | Hase | Dec 2009 | A1 |
20100061753 | Hase | Mar 2010 | A1 |
20100067929 | Seki | Mar 2010 | A1 |
20100074667 | Ehara et al. | Mar 2010 | A1 |
20100092220 | Hasegawa et al. | Apr 2010 | A1 |
20100092221 | Shinshi et al. | Apr 2010 | A1 |
20100202809 | Shinshi et al. | Aug 2010 | A1 |
20100290822 | Hasegawa et al. | Nov 2010 | A1 |
20100303521 | Ogawa et al. | Dec 2010 | A1 |
20110026988 | Yoshikawa et al. | Feb 2011 | A1 |
20110044706 | Iwaya et al. | Feb 2011 | A1 |
20110044734 | Shimokawa et al. | Feb 2011 | A1 |
20110052237 | Yoshikawa et al. | Mar 2011 | A1 |
20110052245 | Shinshi et al. | Mar 2011 | A1 |
20110052277 | Ueno et al. | Mar 2011 | A1 |
20110052282 | Shinshi et al. | Mar 2011 | A1 |
20110058862 | Yamaguchi et al. | Mar 2011 | A1 |
20110058863 | Shinshi et al. | Mar 2011 | A1 |
20110058864 | Fujimoto et al. | Mar 2011 | A1 |
20110058865 | Tokuda et al. | Mar 2011 | A1 |
20110058866 | Ishii et al. | Mar 2011 | A1 |
20110064437 | Yamashina et al. | Mar 2011 | A1 |
20110064443 | Iwaya et al. | Mar 2011 | A1 |
20110064450 | Ishii et al. | Mar 2011 | A1 |
20110064490 | Imada et al. | Mar 2011 | A1 |
20110064502 | Hase et al. | Mar 2011 | A1 |
20110076071 | Yamaguchi et al. | Mar 2011 | A1 |
20110085815 | Kishi et al. | Apr 2011 | A1 |
20110085832 | Hasegawa et al. | Apr 2011 | A1 |
20110091253 | Seo et al. | Apr 2011 | A1 |
20110116848 | Yamaguchi et al. | May 2011 | A1 |
20110129268 | Ishii et al. | Jun 2011 | A1 |
20110150518 | Hase et al. | Jun 2011 | A1 |
20110170917 | Yoshikawa et al. | Jul 2011 | A1 |
20110176821 | Hase | Jul 2011 | A1 |
20110176822 | Ishii et al. | Jul 2011 | A1 |
20110182634 | Ishigaya et al. | Jul 2011 | A1 |
20110182638 | Ishii et al. | Jul 2011 | A1 |
20110194870 | Hase et al. | Aug 2011 | A1 |
20110200368 | Yamaguchi et al. | Aug 2011 | A1 |
20110200370 | Ikebuchi et al. | Aug 2011 | A1 |
20110206427 | Iwaya et al. | Aug 2011 | A1 |
20110211876 | Iwaya et al. | Sep 2011 | A1 |
20110217056 | Yoshinaga et al. | Sep 2011 | A1 |
20110217057 | Yoshinaga et al. | Sep 2011 | A1 |
20110217093 | Tokuda et al. | Sep 2011 | A1 |
20110217095 | Ishii et al. | Sep 2011 | A1 |
20110222875 | Imada et al. | Sep 2011 | A1 |
20110222876 | Yuasa et al. | Sep 2011 | A1 |
20110222888 | Ikebuchi et al. | Sep 2011 | A1 |
20110222929 | Fujimoto et al. | Sep 2011 | A1 |
20110222930 | Fujimoto et al. | Sep 2011 | A1 |
20110222931 | Shinshi et al. | Sep 2011 | A1 |
20110229162 | Ogawa et al. | Sep 2011 | A1 |
20110229178 | Ogawa et al. | Sep 2011 | A1 |
20110229181 | Iwaya et al. | Sep 2011 | A1 |
20110229200 | Yamaguchi et al. | Sep 2011 | A1 |
20110229225 | Ishii et al. | Sep 2011 | A1 |
20110229226 | Tokuda et al. | Sep 2011 | A1 |
20110229227 | Yoshikawa et al. | Sep 2011 | A1 |
20110229228 | Yoshikawa et al. | Sep 2011 | A1 |
20110229236 | Ehara et al. | Sep 2011 | A1 |
20110274453 | Shimokawa et al. | Nov 2011 | A1 |
20110286758 | Yoshinaga | Nov 2011 | A1 |
20110293309 | Hase | Dec 2011 | A1 |
20110311284 | Seo et al. | Dec 2011 | A1 |
20120045226 | Hase et al. | Feb 2012 | A1 |
20120051766 | Ueno et al. | Mar 2012 | A1 |
20120051774 | Ikebuchi et al. | Mar 2012 | A1 |
20120093531 | Yuasa et al. | Apr 2012 | A1 |
20120093551 | Ogawa et al. | Apr 2012 | A1 |
20120107005 | Hase et al. | May 2012 | A1 |
20120114345 | Fujimoto et al. | May 2012 | A1 |
20120114354 | Saito et al. | May 2012 | A1 |
20120121303 | Takagi et al. | May 2012 | A1 |
20120121304 | Tokuda et al. | May 2012 | A1 |
20120121305 | Yoshikawa et al. | May 2012 | A1 |
20120148303 | Yamaguchi et al. | Jun 2012 | A1 |
20120155935 | Yoshikawa et al. | Jun 2012 | A1 |
20120155936 | Yamaguchi et al. | Jun 2012 | A1 |
20120177388 | Imada et al. | Jul 2012 | A1 |
20120177393 | Ikebuchi et al. | Jul 2012 | A1 |
20120177420 | Shimokawa et al. | Jul 2012 | A1 |
20120177423 | Imada et al. | Jul 2012 | A1 |
20120177424 | Saito et al. | Jul 2012 | A1 |
20120207523 | Ueno et al. | Aug 2012 | A1 |
20120219312 | Yuasa et al. | Aug 2012 | A1 |
20120224878 | Ikebuchi et al. | Sep 2012 | A1 |
20120237273 | Yoshinaga et al. | Sep 2012 | A1 |
Number | Date | Country |
---|---|---|
1763652 | Apr 2006 | CN |
101673078 | Mar 2010 | CN |
103207554 | Jul 2013 | CN |
2003-091185 | Mar 2003 | JP |
2004-286922 | Oct 2004 | JP |
2007-334205 | Dec 2007 | JP |
2008-065002 | Mar 2008 | JP |
2008-129517 | Jun 2008 | JP |
2009-003410 | Jan 2009 | JP |
2009-042305 | Feb 2009 | JP |
2009-115969 | May 2009 | JP |
2010-032625 | Feb 2010 | JP |
2010-066583 | Mar 2010 | JP |
2010-096782 | Apr 2010 | JP |
2010-217209 | Sep 2010 | JP |
2010-217210 | Sep 2010 | JP |
Entry |
---|
Office Action issued Feb. 17, 2015 in Chinese Patent Application No. 201310042574.0. |
Number | Date | Country | |
---|---|---|---|
20150168897 A1 | Jun 2015 | US |
Number | Date | Country | |
---|---|---|---|
Parent | 13746871 | Jan 2013 | US |
Child | 14631479 | US |