JP2009237250A - Fixing device and image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a fixing device that smoothes the rough surface layer of a heat roller, resulting from passage of a specific type of paper, and thereby maintains the quality of fixing. <P>SOLUTION: The fixing device 200 includes the heat roller 210, a pressure roller 220, a paper feed cassette 81, a paper-counting section 348, and a polishing roller 240. The heat roller 210 has a main heater 342 and heats the paper. The pressure roller 220 applies pressure to the heat roller 210. The paper feed cassette 81 stores a specific type of paper. The paper counting section 348 counts the specific type of sheets of paper which is picked up in the paper feed cassette 81 and then is passed under the heat roller 210. The polishing roller 240 selectively comes into contact with the paper contact face of the heat roller 210 and polishes the contact face. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a fixing device that fixes an image on a recording medium and an image forming apparatus including the fixing device.

  In an image forming apparatus that creates a copy using an electrophotographic method such as a copying machine or a laser printer, a mechanism for forming a toner image using a dry toner on an image carrier such as a photosensitive drum is provided. Provided. The toner image formed on the photoconductive drum is transferred to a sheet by an image transfer unit, and a mechanism for fixing the sheet carrying the toner image through a fixing device and discharging it as a copy is provided. In general, a heat roller type fixing device is often used as the fixing device. In the heat roller type fixing device, a heating roller provided with a heating source such as a halogen lamp and a pressure roller are arranged to face each other. A predetermined pressure is set between both rollers. Then, the paper carrying the toner image is passed between the two rollers, so that the toner is melted by heat, and the melted toner is pressed against the paper to be fixed.

  Here, in the fixing device, when a certain number of sheets of a certain type are continuously passed, the surface layer of the heating roller is roughened by scratches and the smoothness is deteriorated. The heating roller which has reached such a state has a problem that the surface layer becomes rough and the quality of fixing is deteriorated.

Accordingly, a fixing cleaning device that smoothes the roughness of the surface layer of the heating roller has been proposed (see, for example, Patent Document 1).
JP 09-006174 A

  In the fixing cleaning device described in Patent Document 1, the surface layer of the heating roller is polished by using a web sheet in contact with the heating roller. However, in Patent Document 1, a cleaning unit and a polishing unit are sequentially provided on a web sheet, and when the polishing unit is in contact with the heating roller, the surface layer of the heating roller cannot be removed. It may have an effect. Further, the powder generated during the polishing of the heating roller may reach the nip as it is, which may affect the quality of fixing.

  An object of the present invention is to provide a fixing device that smoothes the roughness of the surface layer of the heating portion caused by the passage of a specific type of recording medium and maintains the quality as fixing.

  The fixing device of the present invention includes a heating unit, a pressure unit, a paper feed cassette, a counting unit, and a polishing unit. The heating unit has a heating source and heats the recording medium. The pressurizing unit pressurizes the heating unit. The paper feed cassette stores a specific type of recording medium. The counting means counts the number of specific types of recording media that pass through the heating section after being picked up by the paper feed cassette. The polishing means selectively contacts the contact surface of the heating unit with the recording medium and polishes the contact surface.

  Here, the polishing means does not contact the contact surface until the count value by the counting means reaches a predetermined value, and contacts the contact surface when the count value by the counting means reaches the predetermined value. Polish the contact surface.

  In this configuration, since the counting means counts the number of recording media of a specific type, the roughness of the contact surface of the heating unit with the recording medium is reflected in the count value compared to the case where the total number of recording media is counted. Since it is easy, the timing which grind | polishes this contact surface with a grinding | polishing means is easy to set. Further, since the polishing means does not contact the contact surface when the count value by the counting means does not reach the predetermined value, the heating unit is not unnecessarily polished.

  In this configuration, it is preferable that the counting unit counts the number of specific types of recording media that pass through the heating unit after being continuously picked up by a paper feed cassette.

  In this configuration, when the number of sheets through which the scratches in the heating unit can be visually recognized passes, the number of sheets passing through the sheet is counted, so that the degree of generation of scratches can be accurately reflected as the count value.

  The counting means preferably resets the count value when a recording medium having a large width in a direction orthogonal to the recording medium conveyance direction is conveyed with respect to a specific type of recording medium.

  In this configuration, scratches in the heating section made of a specific type of recording medium are rubbed by rubbing against another type of recording medium, so the count value is reset and the degree of occurrence of scratches is counted as the count value. It can be reflected accurately.

  Furthermore, it is preferable that the fixing device of the present invention further includes a cleaning unit that cleans a contact surface of the heating unit with the recording medium.

  In this configuration, the residual toner adhering to the heating unit can be wiped off, and the fixing performance can be stabilized.

  In addition, the contact portion between the heating unit and the polishing unit is preferably cleaned by the cleaning unit before reaching the nip portion between the heating unit and the pressurizing unit.

  In this configuration, dirt such as powder generated when the heating unit is polished by the polishing unit can be removed by the cleaning unit, and the fixing performance can be stabilized.

  The image forming apparatus of the present invention includes an image carrier, a charging device, an exposure device, a developing device, a transfer device, and a fixing device of the present invention. An electrostatic latent image is formed on the surface of the image carrier. The charging device charges the surface of the image carrier. The exposure device exposes the surface of the image carrier to form an electrostatic latent image. The developing device develops the electrostatic latent image using a developer to form a developer image. The transfer device transfers the image carrier image on the surface of the image carrier to a recording medium. The fixing device of the present invention has the above-described configuration.

  In this configuration, by providing the fixing device of the present invention, it is possible to perform image forming processing in which quality as fixing is maintained.

  The fixing device according to the present invention can smooth the roughness of the surface layer of the heating portion caused by the passage of a specific type of recording medium and maintain the quality as fixing.

  Hereinafter, a fixing device and an image forming apparatus including the fixing device according to the best embodiment of the present invention will be described in detail with reference to the drawings.

  FIG. 1 is a diagram illustrating a configuration of an image forming apparatus including a fixing device according to an embodiment of the present invention.

  The image forming apparatus 100 forms a multi-color or single-color image on a predetermined sheet (recording medium) according to image data transmitted from the outside. The image processing apparatus 110, the automatic document processing apparatus 120, It is comprised by. The image processing device 110 includes an exposure device 1, a developing device 2, a photosensitive drum (image carrier) 3, a cleaning device 4, a charging device 5, a transfer device 6, a fixing device 200, paper feed cassettes 81 and 83, a paper discharge tray. 91 and the like.

  A document placing table 92 made of transparent glass on which a document is placed is provided above the image processing device 110, and an automatic document processing device 120 is attached to the upper side of the document placing table 92. The automatic document processing device 120 automatically conveys the document on the document placing table 92. Further, the document processing device 120 is configured to be rotatable in the direction of arrow M, and the document can be placed manually by opening the document table 92.

  Image data handled in the image forming apparatus 100 corresponds to a color image using each color of black (K), cyan (C), magenta (M), and yellow (Y). Accordingly, four developing devices 2, photosensitive drums 3, charging devices 5, and cleaning devices 4 are provided so as to form four types of latent images corresponding to the respective colors. Black, cyan, magenta, and yellow are respectively provided. These are set to form four image stations.

  The charging device 5 is a charging means for uniformly charging the surface of the photosensitive drum 3 to a predetermined potential. In addition to the charger type as shown in FIG. 1, a contact type roller type or brush type charging device may be used. Sometimes used. The exposure apparatus 1 is configured as a laser scanning unit (LSU) provided with a laser emitting unit, a reflection mirror, and the like. The exposure apparatus 1 includes a polygon mirror that scans a laser beam, and optical elements such as a lens and a mirror that guide laser light reflected by the polygon mirror to the photosensitive drum 3. In addition, as the exposure apparatus 1, a method using, for example, an EL or LED writing head in which light emitting elements are arranged in an array can also be employed. The exposure apparatus 1 has a function of forming an electrostatic latent image corresponding to the image data on the surface thereof by exposing the charged photosensitive drum 3 according to the input image data. The developing device 2 visualizes the electrostatic latent images formed on the respective photosensitive drums 3 with toner of four colors (YMCK). The cleaning device 4 removes and collects toner remaining on the surface of the photosensitive drum 3 after development and image transfer.

  The transfer device 6 disposed above the photosensitive drum 3 includes an intermediate transfer belt 61, an intermediate transfer belt driving roller 62, an intermediate transfer belt driven roller 63, an intermediate transfer roller 64, and an intermediate transfer belt cleaning unit 65. . Four intermediate transfer rollers 64 are provided corresponding to each color for YMCK.

  The intermediate transfer belt driving roller 62, the intermediate transfer belt driven roller 63, and the intermediate transfer roller 64 are driven to rotate by stretching the intermediate transfer belt 61. Each intermediate transfer roller 64 provides a transfer bias for transferring the toner image on the photosensitive drum 3 onto the intermediate transfer belt 61.

  The intermediate transfer belt 61 is provided in contact with each photosensitive drum 3. A function of forming a color toner image (multicolor toner image) on the intermediate transfer belt 61 by sequentially superimposing and transferring the toner images of the respective colors formed on the photosensitive drum 3 onto the intermediate transfer belt 61. have. The intermediate transfer belt 61 is formed in an endless shape using, for example, a film having a thickness of about 100 μm to 150 μm.

  Transfer of the toner image from the photosensitive drum 3 to the intermediate transfer belt 61 is performed by an intermediate transfer roller 64 that is in contact with the back side of the intermediate transfer belt 61. The intermediate transfer roller 64 is applied with a high-voltage transfer bias (a high voltage having a polarity opposite to the toner charging polarity) in order to transfer the toner image. The intermediate transfer roller 64 is a roller whose base is a metal (for example, stainless steel) shaft having a diameter of 8 mm to 10 mm and whose surface is covered with a conductive elastic material (for example, EPDM, urethane foam, or the like). With this conductive elastic material, a high voltage can be uniformly applied to the intermediate transfer belt 61. In this embodiment, a roller shape is used as the transfer electrode, but a brush or the like can also be used.

  As described above, the electrostatic images visualized on the respective photosensitive drums 3 according to the respective hues are stacked on the intermediate transfer belt 61. Thus, the laminated image information is transferred onto the sheet by the transfer roller 10 disposed at the contact position between the sheet and the intermediate transfer belt 61 by the rotation of the intermediate transfer belt 61.

  At this time, the intermediate transfer belt 61 and the transfer roller 10 are pressed against each other at a predetermined nip, and a voltage for transferring the toner onto the paper is applied to the transfer roller 10 (with a polarity opposite to the charging polarity of the toner). High voltage). Further, in order to obtain the nip constantly, the transfer roller 10 uses either the transfer roller 10 or the intermediate transfer belt 62 as a hard material (for example, metal) and the other as a soft material (for example, an elastic roller). Rubber rollers, foaming resin rollers, etc.).

  Further, as described above, the toner adhered to the intermediate transfer belt 61 due to contact with the photosensitive drum 3 or the toner remaining on the intermediate transfer belt 61 without being transferred onto the sheet by the transfer roller 10 is used in the next step. Therefore, the intermediate transfer belt cleaning unit 65 is configured to remove and collect the toner. The intermediate transfer belt cleaning unit 65 includes a cleaning blade 66 that is in contact with the intermediate transfer belt 61, for example, as a cleaning member. The intermediate transfer belt 61 that is in contact with the cleaning blade 66 from the back side is an intermediate transfer belt driven roller 63. It is supported by.

  The paper feed cassette 81 is a tray for storing a specific type of paper used for image formation, and is provided below the exposure apparatus 1 of the image processing apparatus 110. The paper feed cassette 83 is a tray for storing paper other than a specific type of paper used for image formation, and is provided below the exposure apparatus 1 of the image processing apparatus 110. Further, paper used for image formation can also be placed in the manual paper feed cassette 82. The manual paper feed cassette 82 is a paper feed cassette for manually feeding paper other than the paper stored in the paper feed cassettes 81 and 83. Further, a paper discharge tray 91 provided above the image processing apparatus 110 is a tray for collecting printed sheets face down.

  Further, the image processing apparatus 110 has a substantially vertical sheet conveyance for feeding the sheets in the sheet feeding cassettes 81 and 83 and the manual sheet feeding cassette 82 to the sheet discharge tray 91 via the transfer roller 10 and the fixing device 200. A path S is provided. In the vicinity of the paper transport path S from the paper feed cassettes 81 and 83 or the manual paper feed cassette 82 to the paper discharge tray 91, pickup rollers 11a to 11c, a plurality of transport rollers 12a to 12d, a registration roller 13, a transfer roller 10, A fixing device 200 and the like are arranged. In the vicinity of the paper feed cassette 81, a paper detection sensor 347 is provided.

  The transport rollers 12 a to 12 d are small rollers for promoting and assisting the transport of paper, and a plurality of transport rollers 12 a to 12 d are provided along the paper transport path S. The pickup roller 11 a is provided near the end of the paper feed cassette 81, picks up paper one by one from the paper feed cassette 81, and supplies it to the paper transport path S. The pickup roller 11 b is provided near the end of the manual paper feed cassette 82, picks up paper one by one from the manual paper feed cassette 82, and supplies it to the paper transport path S. The pickup roller 11 c is provided near the end of the paper feed cassette 83, picks up paper one by one from the paper feed cassette 83, and supplies it to the paper transport path S. The paper detection sensor 347 detects the paper picked up by the pickup roller 11a.

  Further, the registration roller 13 temporarily holds the paper conveyed in the paper conveyance path S. The sheet has a function of conveying the sheet to the transfer roller 10 at the timing when the leading edge of the toner image on the photosensitive drum 3 and the leading edge of the sheet are aligned.

  The fixing device 200 includes a heating roller (heating unit) 210 and a pressure roller (pressure unit) 220, and the heating roller 210 and the pressure roller 220 are configured to rotate with a sheet interposed therebetween. The heating roller 210 is set to have a predetermined fixing temperature by a control unit based on a signal from a temperature detector (not shown). The multi-color toner image transferred onto the sheet is melted, mixed, and pressed to be thermally fixed to the paper. An external fixing belt 73 is provided for heating the heating roller 210 from the outside.

  Next, a paper conveyance path will be described. As described above, the image forming apparatus 100 is provided with the paper feed cassettes 81 and 83 and the manual paper feed cassette 82 for storing paper in advance. In order to feed paper from these paper feed cassettes 81 and 83 and manual paper feed cassette 82, pick-up rollers 11a to 11c are arranged to guide the paper one by one to the paper transport path S.

  The sheets conveyed from the sheet feeding cassettes 81 and 83 and the manual sheet feeding cassette 82 are conveyed to the registration rollers 13 by the conveying roller 12a in the sheet conveying path S, and the leading edge of the sheet and the leading edge of the image information on the intermediate transfer belt 61 are conveyed. The sheet is conveyed to the transfer roller 10 at a matching timing, and image information is written on the sheet. Thereafter, the sheet passes through the fixing device 200, whereby the unfixed toner on the sheet is melted and fixed by heat, and is discharged onto the sheet discharge tray 91 through the transport roller 12b disposed thereafter.

  The above-described transport path is for a single-sided printing request for paper, but when a double-sided printing request is made, the trailing edge of the paper that has finished single-sided printing and has passed through the fixing device 200 as described above. When the sheet is held by the final conveying roller 12b, the conveying roller 12b rotates backward to guide the sheet to the conveying rollers 12c and 12d. Then, after printing is performed on the back side of the sheet through the registration roller 13, the sheet is discharged to the discharge tray 91.

  FIG. 2 is a diagram illustrating a configuration of the fixing device according to the embodiment of the present invention.

  The fixing device 200 includes a pair of heating rollers 210 and a pressure roller 220. The sheet is conveyed in the direction indicated by arrow C.

  The heating roller 210 has a configuration in which an elastic layer is provided on the peripheral surface of a metal core, and includes a main heater (heating source) 342 including a halogen heater lamp and a sub heater 343 inside. A temperature detector 340 including a non-contact type thermistor is provided around the heating roller 210, and the surface temperature is controlled by the main heater 342 and the sub heater 343 to be in a range of 160 ° C. to 200 ° C.

  A web sheet type cleaning unit (cleaning means) 250 is provided around the heating roller 210 to wipe off residual toner adhering to the outer peripheral surface of the heating roller 210.

  The cleaning unit 250 includes a web sheet 251, a feed roller 252 that feeds the web sheet 251, a guide roller 253 that applies a predetermined tension and guide to the web sheet 251 fed from the feed roller 252, and an outer peripheral surface of the heating roller 210. A pressure roller 256 that presses the web sheet 251, a take-up roller 254 that winds the used web sheet 251, and a density detection sensor 255 that detects the density of the web sheet 251.

  The web sheet 251 is configured to move little by little from the feed roller 252 toward the take-up roller 254 as indicated by an arrow A. By comprising in this way, a fresh surface can always be made to contact the surface of the heating roller 210, and the dirt of the surface of the heating roller 210 can be wiped off efficiently.

  Further, around the heating roller 210, a polishing roller (polishing means) 240 for polishing the surface of the heating roller 210 (contact surface with the recording medium) is provided. As shown by arrow B, the polishing roller 240 is configured to be able to contact and separate from the heating roller 210.

  The polishing roller 240 is provided on the upstream side of the cleaning unit 250 in the rotation direction of the heating roller 210. By disposing the polishing roller 240 at such a position, the powder generated during the polishing of the heating roller 210 is collected by the cleaning unit 250 before reaching the nip portion.

  FIG. 3 is a view showing a flaw on the surface of the heating roller in the fixing device according to the embodiment of the present invention.

  As an example, the paper P1 indicates an A4R paper, and the paper P2 indicates an A4 paper, each of which is a specific type of paper.

  The sheets P1 and P2 are conveyed in the direction indicated by the arrow D and pass through the heating roller 210. When the sheet P1 passes through the heating roller 210, a flaw 211 is generated on the surface of the heating roller 210 due to the edge of the sheet P1. When the paper P2 passes through the heating roller 210, scratches 212 are generated on the surface of the heating roller 210 due to the edge of the paper P2. The flaw 211 is a fine flaw that cannot be seen with the naked eye when the number of sheets P1 is in units of several sheets, but is conspicuous when the number of sheets P1 is in units of thousands. Similarly, when the number of sheets of paper P2 is several units, it is a fine scratch that cannot be visually recognized by the naked eye. However, when the number of sheets of paper P2 is several thousand, it becomes conspicuous. Therefore, the controller 300 is set so that the surface of the heating roller 210 is polished by the polishing roller 240 before the scratches 211 and 212 affect the quality of fixing.

  FIG. 4 is a block diagram showing the configuration of the fixing device according to the embodiment of the present invention.

  The control unit 300 includes a CPU (Central Processing Unit) 310 and a storage unit 320. The storage unit 320 includes a ROM (Read Only Memory) 322 and a RAM (Random Access Memory) 324.

  The CPU 310 reads the various control programs from the storage unit 320 and executes the read control programs to control the fixing device 200. The ROM 322 stores various control programs and functions, and the stored contents are read out to the CPU 310 as necessary. The RAM 324 functions as a temporary storage holding unit for the CPU 310.

  Note that the control unit 300 may be configured to control not only the fixing device 200 but also the operation of the entire image forming apparatus 100. In that case, the control unit 300 further performs process control related to printing of the image forming apparatus 100.

  Further, when the control unit 300 only controls the fixing device 200, the fixing device 200 may be controlled by communicating with another control unit that controls the operation of the entire image forming apparatus 100. In the following description, it is assumed that the control unit 300 controls the operation of the entire image forming apparatus 100.

  The control unit 300 includes a polishing roller drive unit 241, a feed roller drive unit 251, a take-up roller drive unit 253, a main heater 342, a sub heater 343, and a motor via respective drivers 332, 334, 336, 337, 338, and 339. 344 is connected. The control unit 300 is connected to an image processing apparatus 110, a temperature detector 340, a clock unit 346, and a sheet count unit (counting unit) 348. A sheet detection sensor 347 is connected to the sheet count unit 348.

  The polishing roller driving unit 241 is a motor for causing the polishing roller 240 to contact and separate from the heating roller 210. The delivery roller drive unit 251 is a motor for driving the delivery roller 252. The take-up roller driving unit 253 is a motor for driving the take-up roller 254. The main heater 342 is a heating source that heats the heating roller 210 from the inside. The main heater 342 is provided with the heaters concentrated on the central portion in the width direction of the heating roller 210, and heats the central portion of the heating roller 210. The sub-heater 343 is a heating source that heats the heating roller 210 from the inside. In the sub-heater 343, the heater is concentrated on the end of the heating roller 210 in the width direction, and heats the end of the heating roller 210. Usually, the end of the heating roller 210 corresponding to the sub-heater 343 has a lower temperature than the central portion of the heating roller 210 corresponding to the main heater 342. The motor 344 is a drive source that rotationally drives the heating roller 210 and the pressure roller 220.

  The image processing apparatus 110 is connected to the control unit 300 to control the operation of each unit in the image processing process. The temperature detector 340 is provided around the heating roller 210 and sends the surface temperature of the heating roller 210 to the control unit 300 as data. Based on this, the controller 300 drives the main heater 342 and the sub heater 343 to control the surface temperature of the heating roller 210. The clock unit 346 measures the driving time of the take-up roller driving unit 253 and sends it to the control unit 300 as data. Based on that, the control unit 300 drives the feed roller drive unit 251 to feed the web sheet 251 by a predetermined length. The paper detection sensor 347 is a sensor that detects a specific type of paper picked up from the paper feed cassette 81, and sends the detected data to the sheet count unit 348. The sheet count unit 348 counts the number of sheets of a specific type based on the data sent from the sheet detection sensor 347. When the count value of the sheet count unit 348 reaches a predetermined value, the control unit 300 drives the polishing roller driving unit 241 to bring the polishing roller 240 into contact with the surface of the heating roller 210.

  FIG. 5 is a flowchart illustrating a control procedure of each unit of the image forming apparatus including the fixing device according to the embodiment of the present invention.

  Here, as an example, the predetermined value of the count value is 1000. When recognizing the print start instruction (S1), the control unit 300 controls the image processing apparatus 110 to start printing (S2). When a specific type of paper is picked up, the paper detection sensor 347 detects the paper (S3), and the sheet count unit 348 adds the count value (S4). When the printing is finished (S5), the control unit 300 confirms whether data for the next page exists (S6). If there is no data for the next page, the controller 300 determines whether the count value has reached 1000, that is, whether the heating roller 210 needs to be polished (S7). When the count value reaches 1000, the control unit 300 drives the polishing roller driving unit 241 to bring the polishing roller 240 into contact with the surface of the heating roller 210, and executes the polishing process of the heating roller 210 (S8). When the polishing process is completed, the control unit 300 drives the polishing roller driving unit 241 to separate the polishing roller 240 from the surface of the heating roller 210 and stops the main body of the image forming apparatus 100 (S9).

  FIG. 6 is a diagram showing a scratch on the surface of the heating roller in the fixing device according to the second embodiment of the present invention.

  As an example, the paper P4 indicates an A4R paper, and the paper P5 indicates an A4 paper. The paper P4 is a specific type of paper, and the paper P5 is a paper other than the specific type of paper.

  The paper P4 is conveyed in the direction indicated by the arrow E and passes through the heating roller 210. When the paper P4 passes through the heating roller 210, scratches 213 occur on the surface of the heating roller 210 due to the edge of the paper P4. The flaw 213 is a fine flaw that cannot be visually recognized with the naked eye when the number of sheets of the paper P4 is several units. Therefore, when the number of sheets that can be visually recognized by the naked eye 213 passes, the number of sheets P4 passing through is counted, so that the degree of generation of the scratch 213 can be accurately reflected as a count value.

  As described above, scratches 213 are generated on the surface of the heating roller 210 due to the continuous passing of the paper P4. Thereafter, the paper P5 having a larger width in the direction perpendicular to the paper transport direction than the paper P4 passes through the heating roller 210. Then, the portion of the scratch 213 in the heating roller 210 is polished by rubbing the paper P5 and the scratch 213. Therefore, by resetting the count value counted by the sheet count unit 348 when the paper P5 after the paper P4 is passed, the occurrence of the scratch 213 can be accurately reflected as the count value.

  FIG. 7 is a flowchart showing a control procedure of each part of the image forming apparatus in the fixing device according to the second embodiment of the present invention.

  Here, as an example, the predetermined number of sheets is set to 100, and the predetermined count value is set to 1000. When recognizing the print start instruction (S11), the control unit 300 controls the image processing apparatus 110 to start printing (S12). When a specific type of paper is picked up, the paper detection sensor 347 detects the paper (S13). The controller 300 determines whether or not 100 sheets or more of the sheets are continuously printed (S14). When 100 sheets or more are continuously printed, the count value for the number of sheets is added (S15). When printing is completed (S16), the control unit 300 confirms whether or not data for the next page exists (S17). If there is no data for the next page, the controller 300 determines whether the count value has reached 1000, that is, whether it is necessary to polish the heating roller 210 (S18). When the count value reaches 1000, the control unit 300 drives the polishing roller driving unit 241 to bring the polishing roller 240 into contact with the surface of the heating roller 210, and executes the polishing process of the heating roller 210 (S19). When the polishing process is completed, the control unit 300 drives the polishing roller driving unit 241 to separate the polishing roller 240 from the surface of the heating roller 210 and stops the main body of the image forming apparatus 100 (S20).

  When a specific type of paper is not a print target in S13, the control unit 300 determines whether or not the paper is larger in width in the direction orthogonal to the paper transport direction than the specific type of paper (S21). . When the sheet is a sheet having a width larger than the specific type of sheet in the direction orthogonal to the sheet conveyance direction, the control unit 300 resets the count value of the sheet count unit 348 (S22).

  FIG. 8 is a view showing a state of polishing of the heating roller in the fixing device according to the third embodiment of the present invention.

  In the first and second embodiments of the present invention, the surface of the heating roller 210 is polished using the polishing roller 240. However, in the third embodiment of the present invention, the paper is used without using the polishing roller 240. Is used as a polishing means to smooth the roughness of the surface of the heating roller 210. As the paper as the polishing means, the paper having the maximum width among the papers that can be conveyed in the image forming apparatus 100 is used.

  When the count value by the sheet count unit 348 reaches a predetermined value, the control unit 300 picks up one sheet of paper P3 stored in the paper feed cassette 83 by the pickup roller 11c. Thereafter, the control unit 300 conveys the paper P3 until the leading edge of the paper P3 slightly passes through the heating roller 210, and stops the paper P3. Here, the sheet P3 is sandwiched and fixed by using the registration roller 13, the intermediate transfer belt driving roller 62, and the transfer roller 10. In this state, the heating roller 210 and the pressure roller 220 are idled. The registration roller 13, the intermediate transfer belt driving roller 62, and the transfer roller 10 sandwich the paper P3 with a force that does not cause the paper P3 to be pulled by the idling of the heating roller 210 and the pressure roller 220. Further, the registration roller 13, the intermediate transfer belt driving roller 62, and the transfer roller 10 move the paper P3 little by little when the heating roller 210 and the pressure roller 220 are idle, so that the fresh surface of the paper P3 is always in the nip portion. It can be operated like When the heating roller 210 and the pressure roller 220 are idled for a predetermined time, the paper P3 is transported to the transport roller 12b and discharged to the paper discharge tray 91.

  FIG. 9 is a diagram showing a cleaning procedure after polishing of the heating roller in the fixing device according to the third embodiment of the present invention.

  Here, as the paper for cleaning the heating roller, the paper having the maximum width among the papers that can be conveyed in the image forming apparatus 100 is used.

  After the surface of the heating roller 210 is polished by the paper P3, another sheet stored in the paper feed cassette 83 is picked up by the pickup roller 11c. In the image processing step, the entire surface of one side of the paper is solid-coated. When the solid-coated paper passes through the heating roller 210, the abrasive powder adhering to the surface of the heating roller 210 sticks to the solid-coated paper, and the surface of the heating roller 210 can be cleaned. Here, the solid-coated paper may be reversed by the transport roller 12b and passed through the paper transport path S1, and both surfaces may be solid-coated. The surface of the heating roller 210 can be further cleaned by the inverted solid-coated sheet passing through the heating roller 210 again.

  FIG. 10 is a flowchart showing a procedure for polishing the heating roller in the fixing device according to the third embodiment of the present invention.

  Here, as an example, the predetermined value of the count value is 1000. When the series of printing processes is completed (S31), the control unit 300 determines whether the count value has reached 1000, that is, whether the heating roller 210 needs to be polished (S32). When the count value reaches 1000, the control unit 300 drives the pickup roller 11c to pick up one sheet (S33). This paper is hereinafter referred to as an abrasive paper. The controller 300 conveys the polishing paper to a position where the leading edge of the polishing paper slightly passes through the heating roller 210 without printing the polishing paper (S34), and stops the polishing paper (S35). Here, the abrasive paper is sandwiched and fixed using the registration roller 13, the intermediate transfer belt driving roller 62, and the transfer roller 10 (S36). In this state, the controller 300 idles the heating roller 210 and the pressure roller 220 (S37). The registration roller 13, the intermediate transfer belt driving roller 62, and the transfer roller 10 move the polishing paper little by little when the heating roller 210 and the pressure roller 220 are idle (S38), and always keep the fresh surface of the polishing paper at the nip portion. Make it work. After the heating roller 210 and the pressure roller 220 are idled for a predetermined time, the heating roller 210 and the pressure roller 220 are stopped (S39), and the abrasive paper is conveyed to the conveyance roller 12b and discharged to the paper discharge tray 91 (S40). ).

  After polishing the surface of the heating roller 210 with the polishing paper, another paper stored in the paper feed cassette 83 is picked up by the pickup roller 11c (S41). This sheet is hereinafter referred to as a cleaning sheet. In the image processing step, the control unit 300 paints the entire surface of the cleaning sheet (S42). When the cleaning sheet passes through the heating roller 210 (S43), the abrasive powder adhering to the surface of the heating roller 210 sticks to the cleaning sheet, and the surface of the heating roller 210 can be cleaned. After the cleaning sheet passes through the heating roller 210, the control unit 300 reverses the cleaning sheet by the conveying roller 12b (S44) and passes the sheet conveying path S1, and in the image processing process, the entire back surface of the cleaning sheet is solid-coated. (S45). When the cleaning sheet passes through the heating roller 210 again (S46), the surface of the heating roller 210 can be further cleaned. Thereafter, the cleaning sheet is conveyed to the conveying roller 12b and discharged to the discharge tray 91 (S47). The control unit 300 stops the image forming apparatus 100 after the series of processes (S48).

  In each embodiment, the paper detection sensor 347 for detecting a specific type of paper is provided in the vicinity of the paper feed cassette 81 and detects the paper picked up by the pickup roller 11a. It is not limited. For example, it may be provided on the downstream side of the fixing device 200 and detect only a specific type of paper.

  Finally, the description of the above-described embodiment is to be considered in all respects as illustrative and not restrictive. The scope of the present invention is shown not by the above embodiments but by the claims. Furthermore, the scope of the present invention is intended to include all modifications within the meaning and scope equivalent to the scope of the claims.

1 is a diagram illustrating a configuration of an image forming apparatus including a fixing device according to an embodiment of the present invention. 1 is a diagram illustrating a configuration of a fixing device according to an embodiment of the present invention. FIG. 5 is a diagram illustrating a scratch on the surface of the heating roller in the fixing device according to the embodiment of the present invention. 1 is a block diagram illustrating a configuration of a fixing device according to an embodiment of the present invention. 3 is a flowchart illustrating a control procedure of each unit of an image forming apparatus including a fixing device according to an embodiment of the present invention. It is a figure which shows the crack of the surface of the heating roller in the fixing device which concerns on the 2nd Embodiment of this invention. 10 is a flowchart illustrating a control procedure of each unit of an image forming apparatus in a fixing device according to a second embodiment of the present invention. It is a figure which shows the mode of grinding | polishing of the heating roller in the fixing device which concerns on the 3rd Embodiment of this invention. FIG. 10 is a diagram illustrating a cleaning procedure after polishing of a heating roller in a fixing device according to a third embodiment of the present invention. 10 is a flowchart illustrating a procedure for polishing a heating roller in a fixing device according to a third embodiment of the present invention.

Explanation of symbols

81-paper cassette 200-fixing device 210-heating roller 220-pressure roller 240-polishing roller 342-main heater 348-sheet count unit

Claims (6)

A heating unit having a heating source and heating the recording medium;
A pressurizing unit that pressurizes the heating unit;
A paper cassette for storing a specific type of recording medium;
Counting means for counting the number of specific types of recording media that pass through the heating section after being picked up by the paper feed cassette;
A polishing means for selectively contacting a contact surface with the recording medium of the heating unit and polishing the contact surface;
With
The polishing means does not contact the contact surface until the count value by the counting means reaches a predetermined value. When the count value by the counting means reaches a predetermined value, the polishing means A fixing device that contacts and polishes the contact surface.   2. The fixing device according to claim 1, wherein the counting unit counts the number of specific types of recording media that pass through the heating unit after being continuously picked up by the paper feed cassette.   The fixing device according to claim 1, wherein the count unit resets the count value when a recording medium having a large width in a direction orthogonal to the recording medium conveyance direction is conveyed with respect to a specific type of recording medium.   The fixing device according to claim 1, further comprising a cleaning unit that cleans the contact surface.   The fixing device according to claim 4, wherein a contact portion between the heating unit and the polishing unit is cleaned by the cleaning unit before reaching a nip portion between the heating unit and the pressure unit. An image carrier on which an electrostatic latent image is formed on the surface;
A charging device for charging the surface of the image carrier;
An exposure device that exposes the surface of the image carrier to form an electrostatic latent image;
A developing device for developing the electrostatic latent image using a developer to form a developer image;
A transfer device for transferring the developer image on the surface of the image carrier to a recording medium;
The fixing device according to any one of claims 1 to 5, wherein a developer image on a recording medium is fixed.
An image forming apparatus comprising:

Images