Patent Application
20240160129
This patent application is based on and claims priority pursuant to 35 U.S.C. § 119(a) to Japanese Patent Application No. 2022-180794, filed on Nov. 11, 2022, in the Japan Patent Office, the entire disclosure of which is hereby incorporated by reference herein.
Embodiments of the present disclosure generally relate to a fixing device and an image forming apparatus incorporating the fixing device.
An electrophotographic image forming apparatus includes a fixing device. The fixing device includes a heater, a fixing belt having an endless shape and heated by the heater, and a pressing member in contact with the fixing belt to form a fixing nip. A recording medium on which a toner image is transferred passes through the fixing nip, and heat and pressure in the fixing nip fix the toner image onto the recording medium.
One type of fixing device includes a nip formation pad inside the loop of the fixing belt and the pressing member made of an elastic material. The pressing member is pressed against the nip formation pad via the fixing belt and elastically deformed to form the fixing nip. In the fixing device, the fixing belt slides on the nip formation pad fixed in the fixing device. To reduce a frictional resistance caused by the fixing belt sliding on the nip formation pad, lubricant is applied to the inner face of the fixing belt.
This specification describes an improved fixing device that includes a belt, a pad, a pressure rotator, a lubricant supplier, and a collector. The belt forms a loop. The pad is inside the loop of the belt and contacts the belt. The pressure rotator presses the belt against the pad to form a fixing nip between the belt and the pressure rotator. The lubricant supplier supplies lubricant to an inner face of the belt. The collector collects the lubricant. The collector has a first end and a second end. The first end contacts an inner face of one end of the belt in a width direction of the belt. The second end contacts the inner face of another end of the belt opposite to the one end in the width direction.
This specification also describes an image forming apparatus including the fixing device.
A more complete appreciation of embodiments of the present disclosure and many of the attendant advantages and features thereof can be readily obtained and understood from the following detailed description with reference to 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. The accompanying drawings are not to be considered as drawn to scale unless explicitly noted. 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 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 a similar function, operate in a similar manner, and achieve a similar result.
Referring now to the drawings, embodiments of the present disclosure are described below. 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.
With reference to drawings, descriptions are given below of embodiments of the present disclosure. In the drawings illustrating embodiments of the present disclosure, elements or components having identical or similar functions or shapes are given similar reference numerals as far as distinguishable, and redundant descriptions are omitted.
The intermediate transfer unit 3 includes an intermediate transfer belt 4 as an intermediate transferor, and the intermediate transfer belt 4 is stretched in a loop shape by a plurality of support rollers. The support rollers include a drive roller 5 that rotates the intermediate transfer belt 4 clockwise in
The intermediate transfer belt 4 is stretched in a posture like a substantially inverse triangle. Above an upper face of the stretched intermediate transfer belt 4 that is the upper side of the inverse triangle, four process cartridges 10Y, 10M, 10C, and 10K are arranged side by side in the horizontal direction. The process cartridges 10Y, 10M, 10C, and 10K correspond to yellow, magenta, cyan, and black, respectively.
The process cartridge 10Y includes parts to form a yellow toner image, and the formed yellow toner image is transferred onto the intermediate transfer belt 4. Similarly, the process cartridge 10M includes parts to form a magenta toner image, the process cartridge 10C includes parts to form a cyan toner image, and the process cartridge 10K includes parts to form a black toner image.
The magenta, cyan, and black toner images are transferred from the process cartridges 10M, 10C, and 10K to the intermediate transfer belt 4 at primary transfer positions at which the process cartridges 10M, 10C, and 10K face the primary transfer rollers 9M, 9C, and 9K, respectively. The intermediate transfer belt 4 rotates, and the color toner image primarily transferred onto the intermediate transfer belt 4 reaches a secondary transfer portion 11.
In
As illustrated in
The following describes the process cartridges 10Y, 10M, 10C, and 10K. Since the process cartridges 10Y, 10M, 10C, and 10K have the same configuration except for the color of toner to be used, the process cartridge 10Y is described as a representative.
The process cartridge 10Y includes the photoconductor drum 17Y as an image bearer disposed substantially at the center of the process cartridge 10Y and, around the photoconductor drum 17Y, includes a charging device 18Y to charge the photoconductor drum 17Y and a developing device 19Y to develop the electrostatic latent image formed on the surface of the photoconductor drum 17Y.
In addition, the process cartridge 10Y includes, around the photoconductor drum 17Y, a photoconductor cleaner 20Y to collect untransferred toner remaining on the surface of the photoconductor drum 17Y and a discharger to remove electric charge on the photoconductor drum 17Y. The process cartridge 10Y includes a casing as a common support member supporting the above-described parts and is configured to be integrally attachable to and detachable from the apparatus main body 2 as a single unit to enhance maintainability.
Image forming operations of the image forming apparatus 1 are described below. First, the scanner transmits image data to the controller 21 including a microcomputer and being disposed inside the apparatus main body 2, and the controller 21 decomposes the received image data into four color image data of yellow, magenta, cyan, and black. For example, the controller 21 converts yellow image data into electrical signals and transmits the electrical signals to the exposure unit 12. The exposure unit 12 irradiates the photoconductor drum 17Y with the exposure light L such as laser light based on the yellow image data, i.e., the electrical signals transmitted from the controller 21.
The photoconductor drums 17Y, 17M, 17C, and 17K rotate counterclockwise in
The yellow, magenta, cyan, and black toners are stored in the toner bottles 16 and are supplied to the developing devices 19Y, 19M, 19C, and 19K, respectively. A stirrer in the developing device stirs and mixes the toner and carrier. Stirring the toner with the carrier triboelectrically charges the toner. Developer including the charged toner and the carrier is supplied to the developing roller. The developing roller rotates, and the developer borne on the developing roller passes through the gap between a doctor blade and the developing roller to have a uniform layer thickness. Subsequently, the developer on the developing roller comes into contact with the photoconductor drum, and the toner adheres to the electrostatic latent image on the photoconductor drum. As a result, the toner images are formed on the photoconductor drums 17Y, 17M, 17C, and 17K. The controller 21 controls the exposure units 12 and the devices in the process cartridges 10Y, 10M, 10C, and 10K to periodically form toner patterns on the photoconductor drums 17Y, 17M, 17C, and 17K. Reflection density sensors that are optical sensors detect image densities of the toner patterns on the photoconductor drums 17Y, 17M, 17C, and 17K. Based on the densities detected by the reflection density sensors, the controller 21 controls toner supply to the developing devices 19Y, 19M, 19C, and 19K.
The toner images developed by the developing devices 19Y, 19M, 19C, and 19K and formed on the surfaces of the photoconductor drums 17Y, 17M, 17C, and 17K are primarily transferred onto the intermediate transfer belt 4 at portions at which the photoconductor drums 17Y, 17M, 17C, and 17K face the primary transfer rollers 9Y, 9M, 9C, and 9K. After the primary transfer step, a small amount of untransferred toner that has not been transferred to the intermediate transfer belt 4 remains on the surface of each of the photoconductor drums 17Y, 17M, 17C, and 17K. Photoconductor cleaners 20Y, 20M, 20C, and 20K each include a brush, a roller, or a blade and each remove the untransferred toner on each of the photoconductor drums 17Y, 17M, 17C, and 17K. Subsequently, a discharger in each of the process cartridges removes electric charge on the photoconductor drum and enables starting a next image forming process.
Primarily transferring yellow, magenta, cyan, and black toner images from the process cartridges 10Y, 10M, 10C, and 10K to the intermediate transfer belt 4 and superimposing the toner images on the intermediate transfer belt 4 form a full-color toner image on the intermediate transfer belt 4. The intermediate transfer belt 4 rotates, and the full-color toner image reaches the secondary transfer portion 11. At the same time, one of the sheet trays 13 and 14 is automatically or manually selected. For example, if the sheet tray 13 is selected, a feed roller 22 disposed on the sheet tray 13 rotates to feed one of the sheets S stored in the sheet tray 13 to a conveyance passage K, and the sheet S passes through the conveyance passage K and reaches a registration roller pair 23.
The registration roller pair 23 rotates to convey the sheet S to the secondary transfer portion 11, timed to coincide with the arrival of the full-color toner image on the intermediate transfer belt 4.
A secondary transfer roller 24 in the secondary transfer portion 11 is pressed against a secondary transfer backup roller 6 and contacts the intermediate transfer belt 4 to form a secondary transfer nip, the full-color toner image is transferred from the intermediate transfer belt 4 onto the sheet S in the secondary transfer nip. A conveyor 37 conveys the sheet S to which the full-color toner image is transferred to a fixing device 15, and heat and pressure fix the full-color toner image onto the sheet in the fixing device 15. After the full-color toner image is fixed onto the sheet S, the full-color toner image on the sheet S as an output image is ejected onto an output tray 25.
After passing through the secondary transfer portion 11, the intermediate transfer belt 4 reaches a belt cleaner 26 disposed downstream from the secondary transfer portion 11 in a rotation direction of the intermediate transfer belt 4. The belt cleaner 26 includes a cleaning brush 27 and a cleaning blade 28 and removes residual toner on the intermediate transfer belt 4. Thus, a series of the image forming processes is completed.
The following describes the configuration and operations of the fixing device 15 in the image forming apparatus 1.
In
The fixing belt 29 is an endless belt having a multilayer structure, such as a two-layered belt including a base layer and a release layer or a three-layered belt including the base layer, an elastic layer, and the release layer. The surface of the fixing belt 29 including the elastic layer easily adheres to the toner image and enhances the image quality. The base layer of the fixing belt 29 is made of polyimide, and the release layer is made of perfluoroalkoxy alkane (PFA) or polytetrafluoroethylene (PTFE).
The heating roller 30 includes a heater 30a inside the heating roller 30, the heater 30a heats the heating roller 30, and the heating roller 30 heats the fixing belt 29. The fixing device 15 includes a temperature sensor to detect temperature of the surface of the fixing belt 29 in contact with the heating roller 30. Based on results detected by the temperature sensor, the controller 21 controls power supplied to the heater 30a. The heating roller 30 is rotatably supported by a frame of the fixing device 15 and is driven to rotate by rotation of the fixing belt 29.
The supply roller 31 around which the fixing belt 29 is wound includes a base 31a made of metal and a supplying portion 30b disposed around the base 31a. The base 31a is rotatably supported by a frame of fixing device 15, and a driver such as a motor fixed on the frame drives and rotates the base 31a. The driver drives and rotates the supply roller 31 clockwise in
The supplying portion 31b is made of a nonwoven fabric such as felt, aramid, or polyethylene terephthalate (PET), or a fiber body having heat resistance and oil retention such as perfluoro alkoxyl alkane (PFA) or polytetrafluoroethylene (PTFE) and is impregnated with a low-viscosity lubricant having heat resistance, such as aminosilicone oil.
The tension roller 32 around which the fixing belt 29 is stretched is rotatably supported by a support plate that is movably supported by the frame of the fixing device 15. A compression spring 32a that urges the tension roller 32 leftward in
The sliding pad 33 is fixed on a stay, and the stay is fixed on the frame of the fixing device 15. As a result, the position of the sliding pad 33 does not change even when the pressure roller 35 presses the sliding pad 33, which enables forming a uniform width of the fixing nip. Controlling force pressing the pressure roller 35 enables controlling the width of the fixing nip.
The sliding pad 33 has a nip formation surface along the sheet conveyance direction of the sheet S. To reduce the sliding friction between the sliding pad 33 and the fixing belt 29, a fluororesin layer is disposed on the nip formation surface. The sliding pad 33 has curves at both ends of the nip formation surface. The nip formation surface in the present embodiment has a curved surface but may have a flat surface. The curved surface of the sliding pad 33 is designed so as not to interfere with the conveyance of the sheet S.
The sliding pad 33 is preferably made of a heat-resistant material. This prevents thermal deformation of the sliding pad 33 at temperatures in a fixing temperature range desirable to fix the toner image on the sheet S, retains the fixing nip stably, and stabilizes output image quality.
Examples of the heat-resistant material of the sliding pad 33 include general heat-resistant resin such as polyether sulfone (PES), polyphenylene sulfide (PPS), liquid crystal polymer (LCP), polyether nitrile (PEN), polyamide imide (PAI), and polyether ether ketone (PEEK).
The collector 34 is disposed between the sliding pad 33 and the fixing belt 29. The collector 34 is described later.
The pressure roller 35 is disposed outside the fixing belt 29 and faces the fixing belt 29 on the sliding pad 33. A contact-and-separation mechanism moves the pressure roller 35 to press against or separate from the fixing belt 29 on the sliding pad 33. The pressure roller 35 functions as an elastic body and includes an elastic layer made of, for example, silicon rubber, and the elastic layer forms an outer peripheral surface of the pressure roller 35. The pressure roller 35 presses the sliding pad 33 via the fixing belt 29 and elastically deforms to form the fixing nip N illustrated in
The guide 36 includes a plate fixed on the frame of the fixing device 15 and guides the sheet S conveyed by the conveyor 37 toward the fixing nip N.
Driving and rotating the supply roller 31 rotates the fixing belt 29. The rotation of the fixing belt 29 rotates the heating roller 30. The supplying portion 31b supplies the lubricant to the inner face of the fixing belt 29. The conveyor 37 conveys the sheet S to the fixing device 15, and the guide 36 guides the sheet S to the fixing nip N. The rotation of the pressure roller 35 conveys the sheet S in the fixing nip N. Heat is transmitted from the heater 30a to the sheet S via the heating roller 30 and the fixing belt 29 to melt the toner transferred on the sheet S. and pressure applied by the pressure roller 35 in addition to the heat fixes the toner image onto the sheet S.
In the above-described configuration, since the lubricant supplied from the supply roller 31 to the inner face of the fixing belt 29 has a low viscosity, the lubricant tends to gather at a lower portion of an inner peripheral portion of the fixing belt 29 in the vertical direction in
The following describes a collector 34 of the present embodiment to prevent the occurrence of the above-described disadvantages.
One end of the collector 34 is fixed to the frame of the fixing device 15, and the other end is disposed between the fixing belt 29 and the sliding pad 33. Similar to the supplying portion 31b, the collector 34 is made of the nonwoven fabric such as felt, aramid, or polyethylene terephthalate (PET), or the fiber body having heat resistance and oil retention such as perfluoro alkoxyl alkane (PFA) or polytetrafluoroethylene (PTFE).
As illustrated in
The lubricant moves in a direction indicated by white arrows in
The collector 34 in the above-described configuration collects the lubricant accumulated in the lubricant excess region 38 in which the lubricant is most concentrated on the inner face of the fixing belt 29 and prevents the lubricant from leaking from the both ends of the fixing belt 29. The collector 34 having both ends 34a, 34a contacting the inner face of the fixing belt 29 and another part not contacting the inner face of the fixing belt 29 can minimize the abrasion of the inner peripheral portion of the fixing belt 29 and maintain the durability of the fixing belt 29.
The second collector 40 is made of the same material as that of the collector 34. As illustrated in
In the above-described configuration, even when a supply amount of the lubricant supplied to the fixing belt 29 exceeds an allowable amount that the collector 34 can collect, the second collector 40 absorbs the lubricant outside the fixing belt 29 and prevents the contamination of parts inside the image forming apparatus and the occurrence of the abnormal image.
In the above-described embodiment and modification, the image forming apparatus 1 is the printer forming the full-color toner image as an example of the image forming apparatus according to the present embodiment, but the image forming apparatus is not limited to this. The present disclosure is also adoptable to a copier, a facsimile machine, and a multifunction peripheral (MFP).
In the above-described embodiment, the sheet S is mentioned as an example of the recording medium on which an image is formed and is not limited the standard paper but also includes thick paper, a postcard, a rolled sheet, an envelope, plain paper, thin paper, coated paper, art paper, tracing paper, an overhead projector transparency (OHP sheet or OHP film), a resin film, and any other sheet-shaped material on which an image can be formed.
Aspects of the present disclosure are, for example, as follows.
In a first aspect, a fixing device includes a belt, a pad, a pressure rotator, a lubricant supplier, and a collector. The belt forms a loop. The pad is inside the loop of the belt and contacts the belt. The pressure rotator presses the belt against the pad to form a fixing nip between the belt and the pressure rotator. The lubricant supplier supplies lubricant to an inner face of the belt. The collector collects the lubricant. The collector has a first end and a second end. The first end contacts an inner face of one end of the belt in a width direction of the belt. The second end contacts the inner face of another end of the belt opposite to the one end in the width direction.
In a second aspect, the fixing device according to the first aspect further includes another collector to collect the lubricant. Said another collector has a third end and a fourth end. The third end contacts an outer face of the one end of the belt in the with direction. The fourth end contacts the outer face of said another end of the belt in the width direction.
In a third aspect, the first end and the second end of the collector in the fixing device according to the first aspect or the second aspect contact the inner face of a lower portion of the belt in a vertical direction.
In a fourth aspect, a part of the collector in the fixing device according to any one of the first to third aspects is between the pad and the belt.
In a fifth aspect, the third end and the fourth end of said another collector in the fixing device according to any one of the second to fourth aspects contact the inner face of a lower portion of the belt in a vertical direction.
In a sixth aspect, the first end and the second end of the collector in the fixing device according to any one of the first to fifth aspect are made of fiber.
In a seventh aspect, the third end and the fourth end of said another collector in the fixing device according to any one of the second to sixth aspects are made of fiber.
In an eighth aspect, the first end and the second end of the collector in the fixing device according to any one of the first to seventh aspects are made of nonwoven fabric.
In a ninth aspect, the third end and the fourth end of said another collector in the fixing device according to any one of the second to eighth aspects are made of nonwoven fabric.
In a tenth aspect, the collector in the fixing device according to any one of the first to ninth aspects is longer than the pad in the width direction, and the first end and the second end are respectively at one end and another end of the collector.
In an eleventh aspect, the fixing device according to any one of the first to tenth aspects further includes guide ribs supporting the belt. The first end of the collector contacts the inner face of the belt between one of the guide ribs and the pad, and the second end of the collector contacts the inner face of the belt between another one of the guide ribs and the pad.
In a twelfth aspect, the third end of said another collector in the fixing device according to any one of the second to eleventh aspects is opposed to the first end of the collector via the belt, and the fourth end of said another collector in the fixing device according to any one of the second to eleventh aspects is opposed to the second end of the collector via the belt.
In a thirteenth aspect, an image forming apparatus includes the fixing device according to any one of the first to twelfth aspects.
The above-described embodiments are illustrative and do not limit the present disclosure. Thus, numerous additional modifications and variations are possible in light of the above teachings. For example, elements and/or features of the embodiment and variation may be combined with each other and/or substituted for each other within the scope of the present disclosure.
The advantages achieved by the embodiments described above are examples and therefore are not limited to those described above.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2022-180794 | Nov 2022 | JP | national |
