JP2014021205A - Fixing device and image forming apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a fixing device that maintains the polishing performance of a polishing member over a long period of time and hence prevents the life of the polishing member from being shortened.SOLUTION: A fixing device comprises: a polishing roller 31 composed so as to come into contact with or separate from a fixing belt 4 and configured to polish the surface of the fixing belt 4, thereby recovering the surface condition thereof; and first and second optical sensors 32 and 33, as detecting means for detecting the surface conditions of the areas of the fixing belt 4, through which at least paper edge parts pass. According to the detection results of the first and second optical sensors 32 and 33, the polishing roller 31 can select the contact/separation of the fixing belt 4 with/from at least the paper edge parts.

Description

  The present invention relates to a fixing device and an image forming apparatus, and more particularly to a fixing device that fixes a toner image formed on a recording medium and an image forming apparatus including the same.

  Copying and recording materials are transferred by a fixing device that heats and fixes an unfixed image composed of a toner image transferred and carried on a sheet-like recording medium (hereinafter also referred to as “sheet”) including paper, an OHP sheet, and the like. 2. Description of the Related Art Image forming apparatuses such as electrophotographic copying machines, facsimiles, printers, plotters, or multifunction machines having a plurality of functions are known.

As a fixing device used in such an image forming apparatus, the surface roughness of the fixing member caused by burrs and edge portions in the width direction at the time of cutting the recording medium is recovered by polishing the surface of the fixing member. An abrasive member that can be used has been proposed (see, for example, Patent Document 1).
Further, a control method has been proposed in which the number of sheets passing through the recording medium is counted, and the polishing operation is performed by a polishing roller after the job is completed at the timing when the number of sheets passed reaches a predetermined number (for example, see Patent Document 2). ).

  However, the surface roughness of the fixing member due to the edge portion of the recording medium varies greatly depending on the brand of the paper as the recording medium and the cutting state. The surface roughness of the fixing member tends to be particularly noticeable on a sheet having a large burr height at the edge of the recording medium, whereas an image defect caused by the sheet edge occurs on a sheet having almost no burr at the edge. The level is lighter than that of the former, and the number of sheets to be revealed as image defects is not the same as that of the former. Therefore, when the polishing operation is performed at a predetermined interval, the polishing operation is performed even when the polishing operation is substantially unnecessary, and as a result, the life of the polishing member may be shortened.

  The present invention has been made in view of the circumstances and problems described above, and provides a fixing device that maintains the polishing performance of the polishing member over a long period of time and thus does not shorten the life of the polishing member. Main purpose.

In order to solve the above-described problems and achieve the above-described object, the present invention adopts the following characteristic means / invention specific items (hereinafter referred to as “configuration”).
According to the first aspect of the present invention, there is provided a heating unit, a rotatable fixing member to which heat from the heating unit is transmitted, and the fixing member. The fixing member is pressed against an outer peripheral surface of the fixing member. And a pressure rotator that forms a nip portion between the recording medium and a fixing device capable of fusing and fixing an unfixed toner image by sandwiching and conveying a recording medium carrying an unfixed toner image at the nip portion A polishing member configured to be able to contact and separate from the fixing member, and to recover the surface property by polishing the outer peripheral surface of the fixing member, and at least an edge portion of the recording medium in the fixing member passes. Detecting means for detecting the surface property of the region to be operated, and the polishing member can select a contact / separation state of the fixing member with respect to the outer peripheral surface according to a detection result of the detecting means. And wherein the Rukoto.

According to the present invention, it is possible to realize and provide a novel fixing device capable of solving the problems and achieving the object.
That is, according to the present invention, it is possible to provide a fixing device that maintains the polishing performance of the polishing member for a long period of time and does not shorten the life of the polishing member.

1 is a simplified front view illustrating an overall configuration of an image forming apparatus to which the present invention is applied. 1 is a front view illustrating a fixing device according to an embodiment of the present invention together with its control configuration. (A) is a state in which the surface property of the paper edge portion of the fixing belt is detected by the first optical sensor, and (b) is a state in which the surface property of the paper passing area in the fixing belt is detected by the second optical sensor. It is explanatory drawing explaining each. It is a simple timing chart showing the relationship between the output difference value V3, the contact operation of the polishing roller according to this size, and the print job / time.

  Hereinafter, embodiments of the present invention (hereinafter referred to as “embodiments”) will be described in detail with reference to the drawings. In each of the embodiments and comparative examples, components (members, components, etc.) having the same function and shape are described once by giving the same reference numerals after having been described unless there is a possibility of confusion. Omitted. When quoting and explaining constituent elements such as published patent gazettes, the reference numerals are shown in parentheses to distinguish them from those of the embodiments.

First, an example of an image forming apparatus to which the present invention is applied will be described with reference to FIG. FIG. 1 schematically shows the overall configuration of an image forming apparatus to which the present invention is applied. The image forming apparatus shown in FIG. 1 is a tandem intermediate transfer type full color printer.
The image forming apparatus includes an apparatus main body 100 as an image forming apparatus main body, and a paper feed table 200 that is disposed below the apparatus main body 100 and on which the apparatus main body 100 is placed.

  Inside the apparatus main body 100, image forming units 18Y, 18M, 18C, and 18K (hereinafter also abbreviated as “18Y to K”) as four image forming units are arranged side by side and arranged in a tandem type image forming unit 20. Is configured. Subscripts Y, M, C, and K attached to the symbols of the image forming units 18Y to KY represent yellow, magenta, cyan, and black, respectively.

Each of the image forming units 18Y to 18K includes drum-shaped photoconductors 40Y, 40M, 40C as image carriers that carry Y, M, C, and K color toner images (hereinafter also referred to as “toner images”). 40K (hereinafter also abbreviated as “40Y-K”).
Hereinafter, since the configuration of each of the image forming units 18Y to 18K is the same, only the image forming units 18Y to 18K and the photoconductors 40Y to 40K are attached with a subscript symbol representing the toner color. Further, for simplification of the figure, only the image forming unit 18Y is provided with reference numerals 37, 38, 39 of the apparatus constituting this unit, and is omitted in the other image forming units 18C, 18M, 18K.

  An endless belt-like intermediate transfer belt 10 as an intermediate transfer member is provided below the tandem-type image forming unit 20 and substantially at the center of the apparatus main body 100. The intermediate transfer belt 10 can be rotated and conveyed around the plurality of support rollers 14, 15, 15 ', and 16 in the clockwise direction in the drawing. In the illustrated example, a cleaning device 17 for the intermediate transfer belt is provided on the left of the support roller 16. The cleaning device 17 removes residual toner remaining on the intermediate transfer belt 10 after image transfer.

  On the intermediate transfer belt 10 stretched between the support roller 14 and the support roller 15, the above-described four image forming units 18 </ b> Y to 18 </ b> K are arranged side by side along the conveyance direction, and the tandem image forming unit 20. Is configured.

  Two exposure devices 21 are arranged above the tandem image forming unit 20 as shown in FIG. Each exposure device 21 is arranged corresponding to two image forming units (18Y and 18M, 18C and 18K), respectively. Each exposure device 21 includes, for example, two light source devices (semiconductor laser, semiconductor laser array, or multi-beam light source) and a coupling optical system, a common optical deflector (polygon mirror, etc.), two systems of scanning imaging optical system And the like. In accordance with image information of each color of yellow, cyan, magenta, and black, each color photoconductor 40Y-K is exposed to form an electrostatic latent image.

Around the photoreceptors 40Y to 40K of the image forming units 18Y to 18K, an electrostatic latent image formed by the charging device 37 for uniformly charging each photoreceptor prior to the exposure and the exposure device 21 is provided. A developing device 38 that develops with toner of each color and a photoconductor cleaning device 39 that removes transfer residual toner on the photoconductors 40Y to 40K are provided.
Further, at the primary transfer position where the toner image is transferred from each of the photoconductors 40Y to 40K to the intermediate transfer belt 10, primary transfer means is provided so as to face each of the photoconductors 40Y to 40K with the intermediate transfer belt 10 interposed therebetween. A primary transfer roller 11 is provided as a constituent element.

  Of the plurality of support rollers that support the intermediate transfer belt 10, the support roller 14 is a drive roller that rotationally drives the intermediate transfer belt 10, and is connected to the motor via a drive transmission mechanism (gear, pulley, belt, etc.) not shown. Has been. Further, when a black single color image is formed on the intermediate transfer belt 10, the support rollers 15, 15 'other than the drive roller 14 are moved by a moving mechanism (not shown), and the yellow, cyan, magenta photoreceptor 40Y. , 40M, and 40C can be separated from the intermediate transfer belt 10.

  A secondary transfer device 22 is provided below the intermediate transfer belt 10 on the side opposite to the tandem image forming unit 20. In the illustrated example, the secondary transfer device 22 applies a transfer electric field by pressing the secondary transfer roller 16 ′ against the secondary transfer counter roller 16, thereby transferring the toner image on the intermediate transfer belt 10 to a transfer medium / recording. The image is transferred onto a sheet S as an example of a medium.

  A fixing device 25 that fixes a transfer image (unfixed image) on the paper S is disposed on the left side of the two transfer device 22. The fixing device 25 is a belt fixing method, and is configured by pressing the pressure roller 5 against the fixing belt 4 which is an endless belt. The fixing belt 4 is wound around a heating roller 2 and a fixing roller 3 as supporting rollers as two supporting rotating bodies, and at least one of the rollers has a heat source / heating means (not shown) (heater, lamp, or electromagnetic). An induction heating device or the like) is provided.

  As described above, the fixing device 25 shown in FIG. 1 is a belt fixing system, and includes a heating roller 2 as an example of a heating rotator, a fixing roller 3 as an example of a fixing rotator, and an example of an endless belt. The fixing belt 4, the pressure roller 5 as an example of a pressure rotator, and the heating roller 2 are rotated to rotate the fixing belt 4 in the direction of the arrow (clockwise) as an example of a recording medium. Drive means (not shown) for transporting the paper.

  The sheet S on which the image is transferred by the secondary transfer device 22 is transported to the fixing device 25 by a transport belt 24 supported by two rollers 23. Of course, the portion of the transport belt 24 may be a fixed guide member, or may be a transport roller, a transport roller, or the like. In the illustrated example, the sheet S is reversed and conveyed below the secondary transfer device 22 and the fixing device 25 so as to record images on both sides of the sheet S in parallel with the tandem image forming unit 20 described above. A sheet reversing device 30 is provided.

  When an image forming operation is performed using the image forming apparatus of FIG. 1, the image forming operation is performed based on image information from a personal computer (not shown). Hereinafter, the term “printing” is used in the same meaning as “image formation”. The image forming operation is started in the full color mode or the monochrome mode according to the mode setting set in the operation unit of the personal computer.

  When the full color mode is selected, each of the photoconductors 40Y to 40K rotates in the arrow direction (counterclockwise) shown in FIG. Then, the surface of each of the photoreceptors 40Y to 40K is uniformly charged by the charging device 37. Thereafter, exposure light (laser light or the like) corresponding to the image of each color is irradiated from the exposure device 21 to the photoconductors 40Y to 40K of each color, and electrostatic latent images corresponding to the image data of each color are formed. Each electrostatic latent image is developed with toner of each color by the developing device 38 of each color as the photoreceptors 40Y to 40K rotate. The toner images of the respective colors are sequentially transferred onto the intermediate transfer belt 10 along with the conveyance of the intermediate transfer belt 10 to form a full color image on the intermediate transfer belt. The photoconductors 40Y to 40K after the transfer are subjected to light neutralization by a neutralization lamp, and the transfer residual toner is removed by a cleaning device 39. Therefore, the charging device 37, the exposure device 21, and the developing device 38 constitute an image forming unit that forms images of Y, M, C, and K (toner images) on the photoreceptors 40Y to 40K.

  On the other hand, one of the paper feed rollers 42 arranged in the paper feed table 200 (meaning that they are arranged and arranged, the same applies hereinafter) is selectively rotated, and the paper bank 43 of the paper feed table 200 is arranged in multiple stages. The paper is fed out from one of the paper feed cassettes 44 provided, separated one by one by the separation roller 45, put into the paper feed path 46, transported by the transport roller 47 and led to the paper feed path 48 in the apparatus main body 100, The front end is abutted against the registration roller 49 and stopped. Alternatively, in the case of manual paper feed, the paper feed roller 50 is rotated to feed the paper on the manual feed tray 51, put into the manual paper feed path 53, and the leading end of the paper feeds against the registration roller 49 and stops. Then, the registration roller 49 is rotated in synchronization with the full-color image on the intermediate transfer belt 10, the sheet is fed between the intermediate transfer belt 10 and the secondary transfer device 22, and transferred by the secondary transfer device 22 to be transferred to the sheet. Transfer the toner image on top.

  The sheet on which the toner image has been transferred is conveyed by the secondary transfer device 22 and the conveying belt 24 and sent to the fixing device 25, where the fixing device 25 applies heat and pressure to fix it on the sheet, and is not shown. It is guided to be switched by the switching claw, discharged by the discharge roller 56, and stacked on the discharge tray 57. Alternatively, the conveyance direction is switched by the switching claw (not shown), and the sheet is fed into the sheet reversing device 30, where it is reversed and fed again to the secondary transfer device 22. The paper is discharged onto a paper discharge tray 57 at 56. Thereafter, when the formation of two or more images is instructed, the above-described image forming process is repeated.

When the monochrome mode is selected, the support rollers 15 and 15 ′ move downward to separate the intermediate transfer belt 10 from the photoreceptors 40Y, 40M, and 40C. Only the photoconductor 40K rotates counterclockwise in FIG. 1, and the surface of the photoconductor 40K is uniformly charged by the charging device 37, and exposure light (laser light or the like) corresponding to the K image is irradiated. An electrostatic latent image is formed and developed with K toner from the developing device 38 to form a toner image. This toner image is transferred onto the intermediate transfer belt 10. At this time, the three color photoconductors 40Y, 40M, and 40C other than K and the developing device 38 are stopped, and unnecessary consumption of the photoconductor and the developer is prevented.
On the other hand, paper is fed from the paper feed cassette 44 and conveyed by the registration roller 49 at a timing that coincides with the toner image formed on the intermediate transfer belt 10. The sheet on which the toner image has been transferred is fixed by the fixing device 25 as in the case of a full-color image, and processed through a paper discharge system corresponding to a designated mode. Thereafter, when the formation of two or more images is instructed, the above-described image forming process is repeated.

(Embodiment)
A fixing device according to an embodiment of the present invention will be described in detail with reference to FIGS. FIG. 2 is a diagram for explaining a main configuration of a fixing device according to an embodiment of the present invention together with a control configuration, and FIG. 3A detects the surface property of the paper edge portion of the fixing belt by the first optical sensor. FIG. 3B is a diagram for explaining the state in which the surface property of the sheet passing area of the fixing belt is detected by the second optical sensor. FIG. 4 is a simplified timing chart showing the relationship between the output difference value V3, the contact operation of the polishing roller according to the magnitude, and the print job / time.

  As shown in FIG. 2, the fixing device 1 of the present embodiment has a polishing roller 31, first and second optical sensors 32 and 33, a cleaning unit 34, and a conventional fixing device 25 shown in FIG. 1. The main difference is that the controller 35 is provided. Except for these differences, the configuration of this embodiment is the same as that of the conventional example (image forming apparatus including the fixing device 25) shown in FIG.

The polishing roller 31 is configured to be able to contact and separate from the fixing belt 4 (hereinafter referred to as “contactable”) and to polish the outer peripheral surface of the fixing belt 4 (hereinafter also referred to as “the surface of the fixing belt 4”). It functions as an example of an abrasive member that recovers its surface properties.
The occurrence position of the surface roughness of the fixing belt 4 due to the edges of both ends of the sheet always occurs at a symmetrical position with respect to the center position in the sheet transport direction. Accordingly, the length and position of the polishing roller 31 are set so that the two positions of the fixing belt 4 corresponding to this symmetrical position always come into contact / contact (meaning that they are in contact with each other; the same applies hereinafter). It is set with a margin.

  The polishing roller 31 is rotationally driven by a polishing motor 65 as a polishing member driving means connected to the shaft 31a via a driving force transmission means such as a gear (not shown). The polishing roller 31 is driven to rotate in the forward and forward directions of the fixing belt 4 and is driven to rotate faster than the conveying speed of the fixing belt 4. As a result, it is possible to obtain an effect of rubbing (meaning a state of moving in contact and rubbing with the fixing belt 4; the same applies hereinafter).

  The polishing roller 31 includes a metal layer as a holding layer fixed around the shaft 31a, and a polishing layer as an outermost layer in which abrasive particles are applied to the outer peripheral surface of the metal layer. As the polishing layer, abrasive particles are applied to the outer peripheral surface of the holding layer and fixed with an adhesive. As the abrasive particles, it is preferable to use aluminum oxide (alumina) harder than the surface layer material of the fixing belt 4 and having a particle size of 5 to 30 μm as an abrasive.

A contact / separation mechanism that enables the polishing roller 31 to contact and separate from the fixing belt 4 will be described.
The contact / separation mechanism of the polishing roller 31 includes an arm member 60, a support shaft 61, a tension spring 62, an eccentric cam 63, and a cam motor 64. The arm member 60 is a pair of plate-like members provided on the front side and the back side of the paper surface. One end portion of the arm member 60 rotatably supports the shaft 31a of the polishing roller 31 and can swing about the support shaft 61. It has become. The support shaft 61 is formed to extend toward the front and back of the paper surface, and is supported by a case member (not shown) surrounding the outside of the fixing device 1 so as to be swingable.

  One end of the tension spring 62 is locked to the other end of the arm member 60 (meaning that it is engaged and stopped. The same applies hereinafter), and the other end is locked to the case member (not shown). The tension spring 62 is provided corresponding to the pair of arm members 60. By the tension spring 62, a biasing force (meaning that a momentum is applied; hereinafter the same) is applied to the polishing roller 31 in a direction in which the polishing roller 31 always contacts the fixing belt 4.

  The eccentric cam 63 is fixed to the cam shaft 63 a and is disposed so as to be able to contact and separate from the other end portion of the arm member 60. The cam shaft 63a is rotatably supported by the case member (not shown), and is connected to a cam motor 64 as a cam drive unit via a driving force transmission unit such as a gear (not shown).

  The first and second optical sensors 32 and 33 function as a detection unit or a detection unit that detects a surface property (surface state) of at least a region of the fixing belt 4 through which the paper edge portion passes. The first and second optical sensors 32 and 33 include a light emitting unit that includes a light emitting element that emits (incides) light toward the detected part, and a light receiving element that detects reflected light reflected by the detected part. A light reflection type optical sensor. As the first and second optical sensors 32 and 33, the same optical sensors having the same specifications are used to compare and calculate the intensity of the reflected light at the detected part. Here, as the detected portion, the surface of the paper edge portion of the fixing belt 4 as shown in FIG. 3A and the paper passing area (the paper passing portion or the fixing belt 4 as shown in FIG. 3B). The sheet non-edge portion).

  As shown in FIG. 3A, the first optical sensor 32 is arranged in the width direction perpendicular to the paper transport direction so that the surface property of the paper edge portion of the fixing belt 4 can be detected. As shown in FIG. 3B, the second optical sensor 33 is arranged in the width direction so as to be able to detect the surface property of the sheet passing portion (sheet passing region excluding the edge portions at both ends of the sheet) in the fixing belt 4. ing.

  The image defect caused by the paper edge in the fixing belt 4 is caused by the surface of the fixing belt 4 being roughened by the paper edge portion, and the surface state is different between the paper passing portion which is a non-edge portion and the edge portion. And the edge portion.

  The detection of the surface property of the fixing belt 4 by the first and second optical sensors 32 and 33 will be described with reference to FIG. As shown in FIG. 3A, when the incident light from the first optical sensor 32 is reflected by the surface of the paper edge portion of the fixing belt 4, the surface of the paper edge portion is the surface of the paper passing area. Since it is rougher than that, a part of the incident light diffuses as diffused light. Thereby, the intensity of the output V1 of the reflected light detected by the light receiving unit of the first optical sensor 32 becomes weaker than that of the surface of the paper passing area.

On the other hand, as shown in FIG. 3B, when the incident light from the second optical sensor 33 is reflected by the surface of the sheet passing area of the fixing belt 4, it is smoother than the surface of the sheet edge portion. Therefore, the intensity of the reflected light output V2 becomes relatively strong.
Therefore, the surface roughness of the fixing belt 4 can be detected based on the intensity of the reflected light with respect to the incident light by the first and second optical sensors 32 and 33.

  As described above, the polishing roller 31 as the polishing member is in contact with the surface of the fixing belt 4 as shown in FIG. ) Is made possible to recover. Further, the first position which functions as a detection means or a detection unit capable of detecting the surface property (surface roughness state) of the fixing belt 4 at the downstream position in the rotation / movement direction of the fixing belt 4 from the position where the polishing roller 31 is disposed. And the 2nd optical sensors 32 and 33 are arranged.

  The cleaning unit 34 includes a feed roller 71 that feeds the sheet-like web 70, a pressure roller 72 that presses the fed web 70 against the surface of the fixing belt 4, and a winding roller 73 that winds the used web 70. Have. The pressure roller 72 of the cleaning unit 34 is disposed on the upstream side of the fixing belt 4 in the rotation / movement direction of the fixing belt 4 with respect to the arrangement position of the polishing roller 31.

  The web 70 functions as a cleaning member that cleans the surface of the fixing belt 4 and is made of, for example, a nonwoven fabric. The winding roller 73 is rotationally driven by a winding motor 73 as driving means connected to a shaft via driving force transmission means such as a gear (not shown) as shown only in the control component of FIG.

  A contact / separation mechanism that enables the contact roller 72 to contact and separate from the fixing belt 4 via the web 70 will be briefly described. The contact / separation mechanism of the pressure roller 72 is not illustrated, but is configured by a mechanism similar to the contact / separation mechanism using the eccentric cam and the tension spring of the polishing roller 31 described above. As shown only in the control component of FIG. 2, the pressure roller 72 is configured to be separated from the fixing belt 4 in the direction of the arrow by a contact / separation cam motor 74 disposed in the contact / separation mechanism (not shown). The pressure roller 72 is urged in the direction of the arrow so as to contact the fixing belt 4 by a tension spring disposed in the contact / separation mechanism (not shown).

Here, the heating roller 2, the fixing roller 3, the fixing belt 4, and the pressure roller 5 of the fixing device 1 will be supplementarily explained. A heater lamp 6 as an example of a heat source / heating means is disposed inside the hollow heating roller 2. The heating roller 2, the fixing roller 3, and the pressure roller 5 are supported so as to be rotatable through respective axes in a longitudinal direction (a direction orthogonal to the paper surface of FIG. 1) of the case as the apparatus main body of the fixing device 1. . The heater lamp 6 is fixedly held in the case.
As described above, the fixing device 1 according to this embodiment includes an endless fixing member wound around a heating roller 2 as a heating rotator and a fixing roller 3 as a fixing rotator. The fixing belt 4 as an example, and a pressure rotator that is disposed to face the fixing roller 3 with the fixing belt 4 interposed therebetween and presses the outer peripheral surface of the fixing belt 4 to form a nip portion N with the fixing belt 4. And a pressure roller 5. The heating means may be provided on at least one of the plurality of support rotating bodies.

  The fixing belt 4 is an endless belt formed of, for example, a PI (polyimide) layer having a predetermined thickness, and the outer peripheral surface thereof is coated with an offset preventing agent such as a PFA film.

  The pressure roller 5 is disposed to face the fixing roller 3 with the fixing belt 4 interposed therebetween, and the outer peripheral surface of the fixing belt 4 is pressed toward the center of the fixing roller 3 by contact / separation means (not shown). A nip portion N is formed between the pressure roller 5 and the fixing belt 4 by this pressure state.

  The drive means (not shown) includes a motor and a reduction gear train as drive force transmission means, and is connected and connected to the fixing roller 3 via a gear, and rotates the fixing roller 3 in the direction of the arrow (clockwise) in the figure. It is configured to drive. Due to the rotation of the fixing roller 3, the pressure roller 5 pressed against the fixing roller 3 rotates counterclockwise in the figure and the fixing belt 4 rotates clockwise in the figure at the same speed as the fixing belt 4, respectively.

  The heat generated by the heater lamp 6 built in the heating roller 2 is transmitted to the fixing belt 4 through the heating roller 2 and the fixing belt 4 is heated. Since the pressure roller 5 and the fixing belt 4 rotate in the opposite directions, the sheet is conveyed while the toner image carried (transferred) on the sheet is heated and melted at the nip portion N.

  The main control configuration of the fixing device 1 will be described with reference to FIG. The figure also shows the main control configuration of the fixing device 1. In the figure, the control unit 35 includes a microcomputer having a configuration in which a CPU, a ROM, a RAM, a timer, and the like are connected by a signal bus.

  The CPU of the control unit 35 controls the fixing device 1 based on detection signals from various sensors (first and second optical sensors 32 and 33) provided in the fixing device 1 and an operation program called from the ROM. The operation of the various driving means provided (cam motor 64, polishing motor 65, contact / separation cam motor 74, take-up motor 75) is controlled, and the operation of the entire fixing device 1 is controlled. The ROM stores an operation program for the entire image forming apparatus including the fixing device 1 in advance, and the operation program is appropriately called by the CPU. The RAM has a function of temporarily storing calculation results of the CPU, a function of storing data signals and ON / OFF signals input from various sensors as needed.

  As shown in FIG. 3A, the control unit 35 outputs the detection result of the paper edge portion of the fixing belt 4 by the first optical sensor 32 as an output V1, and as shown in FIG. 3B, the second optical sensor 33. The difference value when the detection result of the paper passing area (paper non-edge portion or paper passing portion) in the fixing belt 4 by the output V2 is V3 = | V2-V1 |, and the output difference value V3 exceeds a predetermined threshold value. In this case, the cam motor 64 is controlled so as to bring the polishing roller 31 into contact with the surface of the fixing belt 4 for a predetermined time, and also functions as a first control means for controlling the polishing motor 54 so as to rotationally drive the polishing roller 31. .

  As shown in FIG. 4, the control unit 35 compares the detection result (output difference value V3) before the start of printing (image formation) with the detection result during printing (output difference value V3) to obtain a predetermined value. If the threshold value is exceeded, the cam motor 64 is controlled so that the polishing roller 31 is brought into contact with the surface of the fixing belt 4 for a predetermined time even during the print job, and the polishing roller 31 is driven to rotate. After controlling the motor 54, it functions as a second control means for continuing printing.

  The controller 35 controls the contact / separation cam motor 74 and the winding motor 75 so that the web 70 contacts the surface of the fixing belt 4 when the polishing roller 31 contacts the surface of the fixing belt 4. 3 functions as a control means.

Next, the polishing operation of the surface of the fixing belt 4 will be described. This operation is executed under a command from the control unit 35.
As described above, in the fixing device 1, for example, when the fixing operation of a standard size paper is continuously performed, the surface of the fixing belt 4 is roughened due to the edges of both ends of the paper. Come. At this time, the surface roughness of the surface of the fixing belt 4 that occurs at a symmetrical position with respect to the center position in the sheet conveyance direction is determined by the first optical sensor 32, and the surface state of the sheet passing area (sheet passing portion) in the fixing belt 4 2 detected by the optical sensor 33.

As shown in FIG. 3A, the control unit 35 outputs the detection result of the sheet edge portion on the fixing belt 4 by the first optical sensor 32 as an output V1, and as shown in FIG. The difference value when the detection result of the sheet passing area (sheet passing portion) in the fixing belt 4 by the sensor 33 is output V2 is V3 = | V2-V1 |, and is predetermined when the output difference value V3 exceeds a predetermined threshold value. During the time, the cam motor 64 is controlled so that the polishing roller 31 is brought into contact with the surface of the fixing belt 4, and the polishing motor 54 is controlled so as to rotationally drive the polishing roller 31.
The predetermined time during which the polishing roller 31 is brought into contact with the surface of the fixing belt 4 is set when the output difference value V3 is equal to or less than a predetermined threshold value or by the result of an experiment or the like. The predetermined threshold value is also set in advance according to the result of the experiment or the like, and is stored in the ROM or the like.

  The operation of bringing the polishing roller 31 into contact with and contacting the surface of the fixing belt 4 is as follows. In FIG. 2, during a normal non-polishing operation, the polishing roller 31 occupies a separated position away from the surface of the fixing belt 4 by the large diameter portion of the eccentric cam 63 coming into contact with the other end portion of the arm member 60. Is in a state. In the state where the polishing roller 31 occupies the separation position, the cam motor 64 is rotationally driven by the command signal from the CPU of the control unit 35, so that the eccentric cam 63 rotates 180 degrees as shown in FIG. The small diameter portion of the eccentric cam 63 is in a non-contact position state facing the other end portion of the arm member 60. As a result, one end portion side (the polishing roller 31 side) of the arm member 60 is swung counterclockwise about the support shaft 61 by the urging force of the tension spring 62, and the polishing roller 31 moves the sheet edge portion of the fixing belt 4. It abuts on the containing surface and occupies the contact position.

  At the same time as the polishing roller 31 occupies the contact position, the polishing motor 65 is driven to rotate in the forward and forward directions of the fixing belt 4 and is driven faster than the conveying speed of the fixing belt 4. As a result, the polishing roller 31 rubs the paper edge portion of the fixing belt 4 for a predetermined time, thereby leveling the paper edge portion of the fixing belt 4 so as to approach the gloss of the paper passing area.

  At the same time as the polishing roller 31 occupies the contact position, the contact / separation cam motor 74 is driven to bring the pressure contact roller 72 into contact with the surface of the fixing belt 4, and the web 70 is moved in the direction of the arrow by driving the winding motor 75. It is paid out. As a result, the surface of the fixing belt 4 is cleaned, so that it is possible to prevent the polishing performance of the polishing roller 31 from being deteriorated due to foreign matter or dirt adhering to the surface of the fixing belt 4.

As described above, the polishing operation by the polishing roller 31 is performed according to the result of detecting the surface state of the fixing belt 4. For example, when the polishing operation is performed after printing (image formation) is completed. In this case, when the next print job is input, an adjustment time due to a predetermined polishing operation occurs, and a waiting time for the user occurs.
Therefore, the operation shown in FIG. 4 is performed. Even during printing, when the surface state of the fixing belt 4 is detected by the first and second optical sensors 32 and 33 and a polishing operation is necessary, it is desirable to perform the polishing operation during printing.

  As shown in FIG. 4, the control unit 35 detects the detection result before the start of printing (image formation) (start of printing of job 1) detected by the first and second optical sensors 32 and 33, and during printing (resumption of printing). ) By comparing and calculating the detection result, printing is performed after controlling the cam motor 64 and the polishing motor 65 so that the polishing roller 31 is brought into contact with the surface of the fixing belt 4 and driven even during the print job. To continue.

  In FIG. 4, after the printing operation of job 1 is started, when “printing temporarily stop grinding roller contact” is set, the output difference value V3 may exceed a predetermined threshold value, so printing is temporarily stopped, At the same time as the polishing roller 31 contacts the surface of the fixing belt 4, the polishing motor 65 rotates. As a result, the sheet edge portion of the fixing belt 4 is leveled so as to approach the gloss of the sheet passing area, so that printing can be resumed.

However, when a polishing operation is performed during printing, offset toner on the surface of the fixing belt 4 that is generated when the paper being printed is fixed adheres to the polishing roller 31 and causes deterioration of the polishing roller 31. There is a fear.
Accordingly, in such a case, the polishing roller 31 occupies the contact position, and at the same time, the contact / separation cam motor 74 is driven to bring the pressure contact roller 72 into contact with the surface of the fixing belt 4 and the winding motor 75 is driven. The web 70 is fed out in the direction of the arrow. As a result, the surface of the fixing belt 4 is cleaned, so that it is possible to prevent the polishing performance of the polishing roller 31 from being deteriorated due to foreign matters adhering to the surface of the fixing belt 4 or dirt such as offset toner. .

As described above, according to the present embodiment, it is possible to provide the fixing device 1 that maintains the polishing performance of the polishing member such as the polishing roller 31 for a long period of time and does not shorten the life of the polishing member. it can.
Further, according to the present embodiment, the polishing operation can be executed even during printing, and the surface property of the fixing belt 4 is recovered before the next print job 2 is input as shown in FIG. be able to.

  In the image forming apparatus including the fixing device 1 described above, adjustment time and standby time due to the polishing operation are suppressed, and high-quality image quality that does not cause image defects due to the edge of the paper is provided over a long period of time. be able to.

The embodiment described above is an example of the present invention, and the present invention has a specific effect for each of the following modes.
[Aspect A]
A heating unit such as a heater lamp 6, a fixing member such as a rotatable fixing belt 4 to which heat from the heating unit is transmitted, and a fixing member are arranged so as to face each other, and the outer peripheral surface of the fixing member is pressed against the fixing member. A pressure rotator such as a pressure roller 5 that forms a nip portion therebetween, and a non-fixed toner image is melted and fixed by nipping and conveying a recording medium such as a sheet carrying an unfixed toner image between the nip portions. In a fixing device such as the fixing device 1 that can be used, a polishing member such as a polishing roller 31 that is configured to be able to contact and separate from the fixing member and recovers its surface property by polishing the outer peripheral surface of the fixing member; And detecting means such as first and second optical sensors 32 and 33 for detecting the surface property of at least the edge of the recording medium in the fixing member. Depending on the stage of the detection result, a contact-separated state to the outer peripheral surface of the fixing member can be selected.

  According to this aspect A, the polishing member can perform the polishing operation only when necessary, and the polishing performance of the polishing member is maintained over a long period of time, thereby preventing the life of the polishing member from being shortened.

[Aspect B]
In aspect A, the detection means includes an optical sensor having a light emitting unit that emits light, and a light receiving unit that detects reflected light reflected by the outer peripheral surface of a fixing member such as the fixing belt 4 from the light emitting unit. The first and second optical sensors are arranged at least in the width direction perpendicular to the rotation direction of the fixing member so as to detect both the edge portion of the recording medium and the non-edge portion of the recording medium in the fixing member. A polishing member such as the polishing roller 31 such as the optical sensors 32 and 33 can select a contact / separation state with respect to the outer peripheral surface of the fixing member according to the intensity of reflected light from the plurality of optical sensors.

  According to the aspect B, as described in the above embodiment, in addition to the effect of the aspect A, the surface roughness of the fixing member can be detected based on the intensity of the reflected light with respect to the incident light by the plurality of optical sensors. .

[Aspect C]
In the aspect B, the detection result of the edge portion of the recording medium in the fixing member by one optical sensor such as the first optical sensor 32 among the plurality of optical sensors is represented by V1 and the non-detection result by the other optical sensor such as the second optical sensor 33. When the detection result of the edge portion is V2, the difference value is V3 = | V2-V1 |, and when the difference value V3 exceeds a predetermined threshold, the polishing member such as the polishing roller 31 is fixed to the fixing belt 4 for a predetermined time. 1st control means, such as the control part 35 made to contact fixing members, such as.

  According to this aspect C, as described in the above embodiment, in addition to the effect of the above aspect B, the control unit 35 and the like based on the detection results of the optical sensors such as the first and second optical sensors 32 and 33 can be used. Since the control operation by the first control unit is executed, the surface state of the fixing member such as the fixing belt 4 that may cause an image defect can be reliably captured.

[Aspect D]
In any one of the aspects A to C, the detection means such as the first and second optical sensors 32 and 33 can operate during image formation, and the detection result before the start of image formation By performing a comparison operation with the detection result during image formation, even in the middle of the image forming job, the second control unit 35 or the like such as the control unit 35 that continues the image formation after contacting the polishing member such as the polishing roller 31. It has a control means.

  According to this aspect D, as described in the above embodiment, the surface state of the fixing member such as the fixing belt 4 is fed back, and an image defect occurs due to the rough surface of the fixing member in the next image forming (printing) job. If predicted, a polishing operation can be performed in advance to prepare for the next image forming job, thereby reducing or eliminating the waiting / waiting time of the user.

[Aspect E]
In any one of the aspects A to D, the outer periphery of the fixing member is located upstream of the fixing member in the rotation direction of the fixing member relative to the position where the polishing member such as the polishing roller 31 is arranged in the fixing member such as the fixing belt 4. A cleaning member such as a web 71 capable of cleaning the surface is provided, and at least when the polishing member is in contact with the fixing member, the cleaning member is in contact with the fixing member.

  According to the aspect E, as described in the above embodiment, the polishing performance of the polishing member such as the polishing roller 31 is deteriorated due to foreign matters or dirt adhering to the surface of the fixing member such as the fixing belt 4. It can be prevented in advance.

[Aspect F]
An image forming apparatus including a fixing device such as the fixing device 1 according to any one of aspects A to E.

  According to this aspect F, as described in the above embodiment, the adjustment time by the polishing operation is suppressed, and high-quality image quality that does not cause image defects due to the edge of the recording medium is provided over a long period of time. be able to.

  The image forming apparatus according to the present invention is not limited to the full-color printer shown in FIG. 1, and may be any image forming apparatus to which the fixing apparatus according to the present invention can be applied. For example, a copying machine, a printer, a facsimile machine, and a plotter can be used. The present invention can also be applied to an image forming apparatus that includes the image forming apparatus or a multi-function peripheral having two or more functions.

  The recording medium is not limited to paper, but includes all recording media and sheets capable of forming an image using an electrophotographic image forming unit, such as thin paper to thick paper, postcard, envelope, or OHP sheet. It is a waste.

  The present invention is not limited to the fixing device 25 that is a belt fixing system, and is, for example, a heating rotator provided with a heating unit, and a heating rotator that is disposed to face the heating rotator and presses the outer peripheral surface of the heating rotator to perform heating rotation. The present invention is also applicable to a fixing device having a pressure rotating body that forms a nip portion with the body.

  The contact / separation mechanism of the cleaning member through the polishing member such as the polishing roller 31 or the pressure contact member such as the pressure roller 72 is not limited to the above-described mechanism, and for example, a mechanism using a spring and a solenoid, or a screw mechanism. It is also possible to configure by using.

  The first optical sensor 32 is not limited to the one that is fixedly disposed at a position facing the edge portion of the sheet in the width direction orthogonal to the rotation / running direction of the fixing belt 4, and corresponds to a change in sheet (sheet) size. You may comprise so that a movement in the said width direction is possible.

1 Fixing Device 2 Heating Roller (Heating Rotator)
3 Fixing roller (fixing rotating body)
4 Fixing belt (an example of fixing member)
5 Pressure roller (an example of a pressure rotator)
6 Heater lamp (example of heating means, heat source)
10 Intermediate transfer belt (intermediate transfer member)
11 Primary transfer rollers 18Y, 18M, 18C, 18K Image forming unit (image forming means)
20 Tandem type image forming unit 31 Polishing roller (an example of a polishing member)
32 1st optical sensor (an example of a detection means)
33 Second optical sensor (an example of detection means)
34 cleaning unit 35 control unit (an example of first and second control means)
37 Charging device 38 Developing device 39 Cleaning device 40Y, 40M, 40C, 40K Photosensitive member (image carrier)
63 Eccentric cam 64 Cam motor 65 Polishing motor 70 Web (an example of a cleaning member)
71 Feeding roller 72 Pressing roller 73 Winding roller 74 Contacting / separating cam motor 75 Winding motor S Paper (sheet-like recording medium)

JP 2008-40364 A JP 2009-237250 A

Claims (6)

A heating unit, a rotatable fixing member to which heat from the heating unit is transmitted, and a fixing member disposed opposite to the fixing member and pressing the outer peripheral surface of the fixing member to form a nip portion with the fixing member A fixing device capable of fusing and fixing an unfixed toner image by sandwiching and transporting a recording medium carrying an unfixed toner image at the nip portion.
A polishing member configured to be able to contact and separate from the fixing member, and to recover the surface property by polishing the outer peripheral surface of the fixing member;
Detecting means for detecting a surface property of at least an edge portion of the recording medium in the fixing member;
The fixing device, wherein the polishing member can select a contact / separation state of the fixing member with respect to the outer peripheral surface in accordance with a detection result of the detection means. The fixing device according to claim 1.
The detection means is an optical sensor having a light emitting unit that emits light and a light receiving unit that detects reflected light reflected from the outer peripheral surface of the fixing member by the light emitted from the light emitting unit,
At least a plurality of the optical sensors are arranged in the width direction orthogonal to the rotation direction of the fixing member so that both the edge portion and the non-edge portion of the recording medium can be detected.
The fixing device, wherein the polishing member is capable of selecting a contact / separation state of the fixing member with respect to the outer peripheral surface according to the intensity of reflected light from the plurality of optical sensors. The fixing device according to claim 2.
When the detection result of the edge portion by the optical sensor is V1, the difference value when the detection result of the non-edge portion is V2 is V3 = | V2-V1 |, and the difference value V3 exceeds a predetermined threshold value A fixing device comprising: a first control unit that brings the polishing member into contact with the fixing member for a predetermined time. The fixing device according to any one of claims 1 to 3,
The detection means is operable during image formation,
By comparing the detection result before the start of image formation and the detection result during image formation, the image formation is continued after contacting the polishing member even during the image formation job. A fixing device having the control means. In the fixing device according to any one of claims 1 to 4,
A cleaning member capable of cleaning the outer peripheral surface of the fixing member is provided on the upstream side in the rotation direction of the fixing member with respect to the arrangement position of the polishing member in the fixing member.
At least when the polishing member is in contact with the fixing member, the cleaning member is in contact with the fixing member.   An image forming apparatus comprising the fixing device according to claim 1.

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