JP2007078787A - Fixing device and image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To allow both an image of low gloss and an image of high gloss to be outputted without enlarging an image forming apparatus and to extend the lifetime of a belt for use in forming the image of high gloss. <P>SOLUTION: When an image forming mode is set to a low gloss mode, a fixing belt is so moved that an ordinary paper with a toner image transferred thereto passes through an area A of the fixing belt, and a nip part, and the ordinary paper is heated and pressurized in the nip part. When the image forming mode is set to a high gloss mode, the fixing belt is so moved that a glossy paper with a toner image transferred thereto passes through an area B of the fixing belt, and the nip part, and glossy paper is heated at a higher temperature than that for the ordinary paper and is pressurized by a higher pressure than that for the ordinary paper, in the nip part, and the fixing belt and the glossy paper which have passed through the nip part are cooled by a cooling device. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an electrophotographic image forming apparatus that forms a glossy image.

In recent years, image forming apparatuses have been developed in color and high definition, and can output high-quality color images similar to photographs. In such an image forming apparatus, when outputting an image taken with a digital still camera, it is preferable that the image is high gloss like a silver halide photograph.
On the other hand, an image output from an image forming apparatus used in an office is generally a low-gloss black and white image mainly composed of characters and line drawings, as represented by a word processor document. In such an image, if the gloss is glossy, it is difficult to see the characters. Therefore, an image forming apparatus that outputs a black and white image adjusts the fixing temperature and fixing time of the toner so that the output image becomes low gloss.
The fixing temperature and fixing time differ between when a low gloss image is output and when a high gloss image is output. For this reason, in order to deal with both low-gloss images and high-gloss images with a single image forming apparatus, for example, as disclosed in Japanese Patent Application Laid-Open No. 2004-133867, the image forming apparatus matches the gloss level of an output image. It is necessary to change the fixing temperature and fixing time.
The image forming apparatus disclosed in Patent Document 1 includes two fixing units. In this image forming apparatus, a recording sheet on which a toner image is transferred is first fixed with a toner image in the first fixing unit. . When a low gloss image is output, the recording paper is discharged from the discharge port. On the other hand, when outputting a highly glossy image, the recording paper is conveyed from the first fixing device to the second fixing device, the toner image is heated and pressurized again, and then cooled and solidified to cool the recording paper surface. The glossiness is increased by improving the smoothness.

In some cases, the glossiness of the output image is changed from another viewpoint. For example, an image forming apparatus disclosed in Patent Document 2 transfers a toner image formed on an intermediate transfer belt onto a recording sheet, and conveys the recording sheet onto which the toner image is transferred together with the intermediate transfer belt to a fixing device. . In this image forming apparatus, the surface of the intermediate transfer belt is divided into a first region in which silicone rubber is uniformly applied to reduce the surface roughness and a second region in which the surface roughness is rough. In this image forming apparatus, when the toner image is transferred to the recording paper using the second area and passed through the fixing device while the second area and the recording paper are kept in close contact with each other, the surface roughness of the intermediate transfer belt is reduced. Since it is small, the surface of the toner image fixed on the recording paper becomes smooth, and the gloss increases as compared with the case where the surface roughness is rough.
JP 2005-173259 A JP 2001-154510 A

  In the apparatus disclosed in Patent Document 1, the use of the second fixing device makes the fixing temperature and fixing time different from those when outputting a low-gloss image, thereby obtaining a high-gloss image. However, when the two fixing devices are housed in the casing as in the image forming apparatus disclosed in Patent Document 1, there arises a problem that the casing of the image forming apparatus becomes large.

  In the apparatus disclosed in Patent Document 2, when a toner image is transferred using an area where the surface roughness of the intermediate transfer belt is small, and the second area and the recording paper are kept in close contact with each other, the gloss is obtained. A certain image can be obtained. However, in the apparatus disclosed in Patent Document 2, a region with a small surface roughness of the intermediate transfer belt can be brought into contact with the recording paper without distinguishing between plain paper and glossy paper. In areas with small surface roughness, silicone rubber is uniformly applied to reduce the surface roughness, but when plain paper comes into contact, the surface of the silicone rubber is damaged by plain paper fibers and plain paper surface additives. And the surface uniformity is rapidly reduced. In this way, if the surface uniformity decreases rapidly and a high gloss image cannot be obtained, the belt must be replaced immediately, which causes problems in terms of the life of the intermediate transfer belt and the maintenance of the device. is there.

  The present invention has been made under the above-described background, and an object of the present invention is to enable output of both a low-gloss image and a high-gloss image without increasing the size of the image forming apparatus. It is to extend the life of a belt used to form an image.

  In order to solve the above-described problem, the present invention provides a first roll, a second roll that faces the first roll across a conveyance path of a sheet on which a toner image has been transferred, and the first roll that has a first load. Or a pressing means that presses against the second roll with a second load larger than the first load, and a nip portion between the first roll and the second roll, and a first region and a second region. The endless belt that is held between the endless belt, the sheet conveyed to the nip portion, and the endless belt that is in the nip portion together with the sheet at a first temperature or a second temperature that is higher than the first temperature. A heat source that heats and a cooling device that is downstream of the conveyance path as viewed from the nip portion and that cools the sheet attached to the endless belt by being heated and pressurized in the nip portion and passing through the nip portion And features an image When the composition mode is the low gloss mode, the endless belt is moved so that the sheet passes through the nip portion together with the first region, and the heat source is the first temperature, the sheet, the endless belt, When the image forming mode is the high gloss mode, the pressing means presses the first roll with a first load, and the sheet passes through the nip portion together with the second region. An endless belt is moved, the heat source heats the sheet and the endless belt at the second temperature, and the pressing unit presses the first roll with a second load. .

  According to the present invention, it is possible to output both a low-gloss image and a high-gloss image without enlarging the image forming apparatus, and a belt used for forming a high-gloss image. Can extend the lifetime of

[Configuration of the embodiment]
FIG. 1 is a diagram showing an image forming apparatus 100 according to an embodiment of the present invention. The image forming apparatus 100 fixes an image forming unit 3 that forms a toner image on a recording sheet, a paper feeding unit 4 that supplies the recording sheet to the image forming unit 3, and a toner image formed on the recording sheet. A fixing / discharge unit 5 that discharges the recording paper and a control unit 1 that controls the above-described units are provided.

  The control unit 1 includes a control unit 10, an operation unit 11, and a communication unit 12. The control unit 10 includes a CPU (Central Processing Unit), a ROM (Read Only Memory), a RAM (Random Access Memory), and the like, and controls each unit of the image forming apparatus 100 by executing a control program stored in the ROM. . The operation unit 11 includes a liquid crystal display and a plurality of buttons (all not shown), and accepts various input instructions by the user such as selection of an image forming mode. The communication unit 12 receives image data and various messages transmitted from an external device such as a personal computer (not shown). Note that the image forming apparatus 100 of the present embodiment includes a low gloss mode for performing low gloss printing and a high gloss mode for performing high gloss printing as the image forming mode.

  The image forming unit 3 forms an image based on image data supplied from an external device such as a personal computer (not shown). More specifically, the image forming unit 3 rotates the photoreceptors 301Y and 301M that rotate in the direction of the arrow a in the drawing for each color of yellow (Y), magenta (M), cyan (C), and black (K). , 301C, 301K. The chargers 302Y, 302M, 302C, and 302K are devices that charge the above-described photoreceptor to a uniform potential. The photosensitive member charged by each charger is exposed to light output from the exposure units 303Y, 303M, 303C, and 303K. Each exposure unit outputs exposure light modulated based on image data of each color of YMCK to a charged photoconductor, and forms an electrostatic latent image of each color of YMCK on the photoconductor.

  The developing devices 304Y, 304M, 304C, and 304K are for developing the electrostatic latent images formed on the respective photosensitive members. Each developing machine develops the electrostatic latent image formed on the corresponding photoconductor with toner, and forms a toner image on the photoconductor. The cleaners 305Y, 305M, 305C, and 305K are devices that clean toner remaining on the photoreceptor without being transferred to the intermediate transfer belt 308. Toner remaining on the photosensitive member without being transferred to the intermediate transfer belt 308 is collected by each cleaner. Erase lamps 306Y, 306M, 306C, and 306K are lamps that erase the electrostatic latent image on the photoreceptor. The electrostatic latent image on the photoreceptor from which the toner has been collected by each cleaner is erased by each erase lamp.

  The intermediate transfer belt 308 onto which the toner image of each photoconductor is transferred is stretched between a drive roll 309 and a counter roll 311 and is in the direction of arrow b in the figure while being in contact with the photoconductors 301Y, 301M, 301C, 301K. Move around.

  The primary transfer rolls 307Y, 307M, 307C, and 307K are disposed at positions facing the photoreceptors 301Y, 301M, 301C, and 301K with the intermediate transfer belt 308 interposed therebetween. Each primary transfer roll forms a nip region with the corresponding photosensitive member, and the toner images on the peripheral surfaces of the photosensitive members 301Y, 301M, 301C, and 301K are transferred to the intermediate transfer belt 308 in the nip region. Further, the secondary transfer roll 310 is disposed at a position facing the opposing roll 311 with the intermediate transfer belt 308 interposed therebetween. The secondary transfer roll 310 forms a nip area with the opposing roll 311, and secondarily transfers the toner image on the intermediate transfer belt 308 onto the recording paper P.

  The paper feed unit 4 includes a plurality of paper trays 41 for storing various recording papers, a plurality of feed rolls 42 for feeding the recording papers from the paper trays 41, and a plurality of transport rolls 43 for transporting the recording papers. At the time of formation, the recording paper is supplied to the secondary transfer position. There are two types of recording paper used in this embodiment, so-called plain paper and glossy paper. Here, the glossy paper is a recording paper provided with a coat layer mainly composed of a thermoplastic resin on plain paper, for example, a sheet mainly composed of a thermoplastic resin made of polyester or the like, having a thickness of 5 to 20 μm. The thickness is provided on the surface of the base material, and a transparent coat layer is provided on the surface of the base material. A smooth surface can be obtained by embedding toner in the coat layer. When glossy paper is used to form an image in high gloss mode, not only the toner image part but also the coat layer part is melted and solidified by heating and cooling, so the entire recording surface of the glossy paper becomes glossy. Will have.

  The fixing / paper discharge unit 5 includes a fixing device 51 and a paper discharge tray 52. FIG. 2 is a diagram illustrating the configuration of the fixing device 51. As shown in the figure, the fixing device 51 includes a fixing roll 521, a pressure roll 522, a cooling device 523, a peeling roll 524, guide members 525 a and 525 b, a steering roll 526, and a fixing belt 527. And discharge rolls 528a and 528b.

  The fixing roll 521 is formed of a metal having high thermal conductivity, and a release layer 521a made of a fluororesin such as a PFA tube is provided on the surface. Further, inside the fixing roll 521, for example, a heat source 521b such as a halogen lamp is disposed. The heat source 521b is controlled by the control unit 10 according to the image forming mode. Further, the fixing roll 521 is rotated by a motor (not shown) to move the fixing belt 527 around in the direction of arrow r in the drawing.

  The pressure roll 522 is made of a metal having high thermal conductivity, and faces the fixing roll 521 with the recording paper conveyance path and the fixing belt 527 interposed therebetween. An elastic layer 522a made of silicone rubber having a rubber hardness (JIS-A) of about 40 ° is provided on the surface of the pressure roll 522. The surface of the elastic layer 522a is made of a fluororesin such as a PFA tube. A release layer 522b is provided. Further, inside the fixing roll 521, for example, a heat source 522c such as a halogen lamp is disposed. The heat source 522c is controlled by the control unit 10 according to the image forming mode. The support shaft 522d that supports the pressure roll 522 is pressed toward the fixing roll 521 by a spring 522e as illustrated in FIG. One end of the spring 522e is fixed to the support shaft 522d, and the other end is fixed to the moving member 522f. The load that the fixing roll 521 receives from the pressure roll 522 is changed by displacing the position of the moving member 522f. Specifically, when the moving member 522f is moved closer to the support shaft 522d, the load received by the fixing roll 521 from the pressure roll 522 increases, and when the moving member 522f is moved away from the support shaft 522d, the fixing roll 521 is pressed. The load received from the roll 522 is reduced. The position of the moving member 522f is controlled by the control unit 10 according to the image forming mode. The moving member 522f moves toward the fixing roll 521 in the high gloss mode, and the moving member 522f is the fixing roll in the low gloss mode. Move away from 521.

  The fixing belt 527 is an endless belt in which a silicone rubber coating layer having a thickness of 35 μm is formed on a thermosetting polyimide film, and the surface of the coating layer (belt outer peripheral surface) is finished extremely smooth. Although the fixing belt 527 is preferably thin, the polyimide base material is 75 μm or more from the viewpoint of strength, and the coating layer is 30 μm or more from the viewpoint of fixing the toner image on the recording paper in close contact with the toner image on the recording paper. It is desirable. The fixing belt 527 is rotated in a direction indicated by an arrow r in the drawing while being stretched by a plurality of members including a fixing roll 521, a peeling roll 524, and a steering roll 526, and is fixed between the fixing roll 521 and the pressure roll 522. When the paper passes through the nip portion, the recording paper conveyed to the nip portion passes through the nip portion. The fixing belt 527 is divided into a region A that contacts plain paper and a region B that contacts glossy paper as illustrated in FIG. 4, and a seal that reflects light on the inner peripheral surface of the region B. 527a is attached.

  The sensor 529 is an optical sensor for detecting the region B of the fixing belt 527 and is disposed on the inner side of the inner peripheral surface of the fixing belt 527. The sensor 529 outputs light toward the inner peripheral surface of the fixing belt 527, and detects light reflected by the fixing belt 527 or the seal 527a. Based on the detected light amount, a signal indicating whether the region facing the sensor 529 is the region A or the region B is output.

  The cooling device 523 includes a heat sink 523a and a cooling fan 523b that cools the heat sink 523a. The heat sink 523a is formed of a material having high thermal conductivity such as aluminum and includes a plurality of heat radiation fins. The heat sink 523a is disposed along the inner peripheral surface of the fixing belt 527, and contacts the inner peripheral surface of the fixing belt 527 that moves around and cools the fixing belt 527 and the recording paper on the fixing belt 527. Further, the cooling fan 523b is controlled by the control unit 10 according to the image forming mode, and does not blow in the low gloss mode, and blows in the high gloss mode to cool the heat sink 523a.

  The metal peeling roll 524 changes the traveling direction of the fixing belt 527 that is stretched. When the fixing belt 527 comes to the position of the peeling roll 524, the traveling direction of the fixing belt 527 changes. Here, since the recording paper adhering to the fixing belt 527 has rigidity, the recording paper does not move along the fixing belt 527 and gradually peels from the leading end portion in the direction of the guide members 525a and 525b. Moving.

  The guide members 525 a and 525 b are members that guide the recording sheet peeled from the fixing belt 527 to between the discharge roll 528 a and the discharge roll 528 b, and are disposed in the vicinity of the release roll 524. The recording sheet peeled from the fixing belt 527 is guided between the discharge roller 528a and the discharge roller 528b through the guide member 525a and the guide member 525b.

  The discharge roll 528 a and the discharge roll 528 b are rolls that discharge the recording paper to the paper discharge tray 52. The discharge roll 528a and the discharge roll 528b are opposed to each other across the conveyance path of the recording paper, and the discharge roll 528a is pressed by the discharge roll 528b. The discharge roll 528 b is rotated by a motor (not shown), and the recording sheet guided to the nip portion between the discharge roll 528 a and the discharge roll 528 b is conveyed to the discharge tray 52.

  The metal steering roll 526 changes the traveling direction of the fixing belt 527 that moves around. One end of the steering roll 526 is fixed, and the other end is moved by a driving device (not shown). By tilting the steering roll 526 by moving the end portion by the driving device, the fixing belt 527 moving around is displaced in the axial direction and moved toward one of the end portions. As a result, the position of the fixing belt 527 offset to the end of the steering roll 526 during the circular movement is returned to the original position.

[Operation of the embodiment]
Next, the operation of this embodiment will be described. In the following description, the operation when the low gloss mode is selected as the image forming mode will be described first, and then the operation when the high gloss mode is selected as the image forming mode will be described.

[Operation when low gloss mode is selected]
For example, when a message indicating a low gloss mode is transmitted from a computer device such as a personal computer together with image data generated by a digital camera or the like, the transmitted image data and message are received by the communication unit 12. . When the communication unit 12 receives the image data and the message, the image forming process is started under the control of the control unit 10. First, the paper feed unit 4 is controlled, and plain paper stored in the paper tray 41 is conveyed to the image forming unit 3. The image forming unit 3 forms a toner image based on the received image data, and transfers the formed toner image onto plain paper. Then, the plain paper on which the toner image is transferred is conveyed to the fixing / discharge unit 5.

  Next, in the fixing / discharge unit 5, the control unit 10 controls a motor that rotates the fixing roll 521, heat sources 521 b and 522 b, a moving member 522 f, and a cooling fan 523 b. Specifically, first, the control unit 10 drives a motor that rotates the fixing roll 521 to rotate the fixing roll 521 and move the fixing belt 527 around. Then, a signal output from the sensor 529 is monitored, and an area of the fixing belt 527 facing the sensor 529 is detected. When the control unit 10 detects from the signal output from the sensor 529 that the portion of the fixing belt 527 facing the sensor 529 has changed from the region B to the region A, the portion of the region A is fixed together with the plain paper. The motor is driven to move the fixing belt 527 so as to enter the nip portion between the roll 521 and the pressure roll 522. The control unit 10 also controls the heat source 521b and the heat source 522c so that the heat transferred to the plain paper via the pressure roll 522, the fixing roll 521, and the fixing belt 527 melts the toner transferred to the plain paper. Temperature control of 521b and 522b is performed. In addition, the control unit 10 stops the cooling fan 523b and moves the position of the moving member 522f away from the fixing roll 521 so that the load received by the fixing roll 521 from the pressure roll 522 is reduced.

  When the plain paper on which the toner image is formed is conveyed to the fixing device 51 in which each part is controlled in this way, the plain paper is transferred to the nip portion between the fixing roll 521 and the pressure roll 522 together with the area A of the fixing belt. Then, it is heated and pressurized by the fixing roll 521 and the pressure roll 522. Here, in the low gloss mode, the temperature at the time of fixing and the pressure at the time of fixing are controlled, and as shown in FIG. 5B, the toner transferred onto the surface of the plain paper is melted on the plain paper and the plain paper. As a result, irregularities are formed on the surface of the paper, and the image on the plain paper has no gloss. The plain paper that has passed through the nip moves together with the fixing belt 527 and is conveyed to the position of the heat sink 523a. When the plain paper is conveyed to the position of the heat sink 523a, the toner on the plain paper is cooled through the fixing belt 527. Then, the plain paper that has passed through the nip moves together with the fixing belt 527, is conveyed to the position of the peeling roll 524, and is peeled off from the fixing belt 527. The plain paper peeled off from the fixing belt 527 passes between the guide members 525a and 525b and is then discharged to the paper discharge tray 52 by the discharge rolls 528a and 528b.

[Operation when high gloss mode is selected]
Next, the operation when the high gloss mode is selected will be described. When a message instructing the high gloss mode is transmitted together with image data generated by a digital camera or the like from a computer device such as a personal computer, the transmitted image data and message are received by the communication unit 12. When the communication unit 12 receives the image data and the message, the image forming process is started under the control of the control unit 10. First, the paper feed unit 4 is controlled, and glossy paper stored in the paper tray 41 is conveyed to the image forming unit 3. The image forming unit 3 forms a toner image based on the received image data, and transfers the formed toner image to glossy paper. The glossy paper onto which the toner image has been transferred is conveyed to the fixing / discharge unit 5.

  Next, in the fixing / discharge unit 5, the control unit 10 controls a motor that rotates the fixing roll 521, heat sources 521 b and 522 b, a moving member 522 f, and a cooling fan 523 b. Specifically, first, the control unit 10 drives a motor that rotates the fixing roll 521 to rotate the fixing roll 521 and move the fixing belt 527 around. Then, a signal output from the sensor 529 is monitored, and an area of the fixing belt 527 facing the sensor 529 is detected. When the control unit 10 detects from the signal output from the sensor 529 that the portion of the fixing belt 527 facing the sensor 529 has changed from the region A to the region B, the portion of the region B is fixed together with the glossy paper. The motor is driven to move the fixing belt 527 so as to enter the nip portion between the roll 521 and the pressure roll 522. Further, the control unit 10 controls the temperature of the heat sources 521b and 522b so that the temperature of the heat sources 521b and 522b is higher than that in the plain paper mode. In addition, the control unit 10 operates the cooling fan 523b and moves the position of the moving member 522f toward the fixing roll 521 so that the load received by the fixing roll 521 from the pressure roll 522 is increased.

  When the glossy paper on which the toner image is formed is conveyed to the fixing device 51 in which each part is controlled as described above, the glossy paper is transferred to the nip portion between the fixing roll 521 and the pressure roll 522 together with the area B of the fixing belt. Then, it is heated and pressurized by the fixing roll 521 and the pressure roll 522. Here, the temperature of the heat sources 521b and 522b is higher than that in the plain paper mode, and the load that the fixing roll 521 receives from the pressure roll 522 is higher than that in the plain paper mode. ing. For this reason, the toner image formed on the glossy paper is heated and pressurized at a nip portion with higher heat and pressure than those of plain paper. Then, as shown in FIG. 5A, the toner is embedded in the coat layer on the surface of the glossy paper, and the melted toner comes into close contact with the outer peripheral surface of the fixing belt 527 so that the surface becomes smooth. .

  The glossy paper that has passed through the nip moves together with the fixing belt 527 and is conveyed to the position of the heat sink 523a. When the glossy paper is conveyed to the position of the heat sink 523a cooled by the cooling fan 523b, the toner embedded in the glossy paper is cooled and solidified through the fixing belt 527, and the glossy paper surface is smooth and glossy. It will be. Here, since the heat sink 523a is cooled by the cooling fan 523b, the glossy paper is cooled to a temperature lower than that of plain paper. Thereafter, the glossy paper on the fixing belt 527 is conveyed to the position of the peeling roll 524 and peeled off from the fixing belt 527. The glossy paper released from the fixing belt 527 passes between the guide members 525a and 525b, and is then discharged to the paper discharge tray 52 by the discharge rollers 528a and 528b.

  FIG. 7 shows the results of image formation when the image forming apparatus of the above-described embodiment is operated under the operating conditions shown in FIG. When the region B was provided on the fixing belt 527 corresponding to the high gloss mode and the toner image formed on the glossy paper was fixed using the region B, a high gloss image could be obtained.

  As described above, according to the present embodiment, a single fixing device forms both a low-gloss image and a high-gloss image by changing the fixing temperature, fixing pressure, and cooling temperature. can do. Further, when the surface of the fixing belt becomes rough, the image formed on the glossy paper is scratched and the image quality is deteriorated. However, in this embodiment, in the glossy paper mode, the same area (area) of the fixing belt 527 is used. B) always contacts smooth glossy paper. Therefore, the surface of the fixing belt 527 where the glossy paper comes into contact is not roughened, and a high-gloss image can be formed for a long period of time. Further, since the fixing is performed with one fixing device, it is possible to suppress the amount of generated heat and the consumed power.

[Modification]
As mentioned above, although embodiment of this invention was described, this invention is not limited to embodiment mentioned above, It can implement with another various form. For example, the present invention may be implemented by modifying the above-described embodiment as follows.

  In the fixing belt 527, the region B that contacts the plain paper may be laminated with a material different from the region A that contacts the glossy paper, such as PFA, silicone, or Teflon (registered trademark). Further, when the fixing belt 527 is stopped after the image formation is completed, the fixing may be stopped when the region A is at the nip portion between the fixing roll 521 and the pressure roll 522.

  In the embodiment described above, the load applied to the fixing roll 521 is adjusted by the moving member 522f and the spring 522e, but the position of the support shaft 522d that supports the pressure roll 522 is adjusted by the cam in the direction of the fixing roll 521 or The load applied to the fixing roll 521 from the pressure roll 522 may be adjusted by displacing the fixing roll 521 in the opposite direction.

  A configuration for cleaning the region B as shown in FIG. 8 may be provided in the fixing device 51. In FIG. 8, a driven roll 531 a is a roll around which an adhesive belt 530 having adhesiveness is wound, and a winding roll 531 b is a roll that winds up the adhesive belt 530. The cleaning roll 531 c is a roll for bringing the adhesive belt 530 into contact with the fixing belt 527, and its position is controlled by the control unit 10. The control unit 10 monitors the position of the region B based on a signal from the sensor 529, and when an image is formed on a predetermined number of glossy papers, the winding roll 531b is rotated by a motor (not shown) to wind up the adhesive belt 530. . Then, the cleaning roll 531c is moved in the direction of the steering roll 526. As a result, the adhesive belt 530 comes into contact with the fixing belt 527, and dust or the like adhering to the outer peripheral surface of the fixing belt 527 adheres to the adhesive belt 530, and the fixing belt 527 is cleaned.

  In the embodiment described above, the cooling device 523, the peeling roll 524, and the steering roll 526 may be moved according to the image forming mode. FIG. 9A is a diagram illustrating the configuration of the fixing device 51 according to this modification. In FIG. 9A, a peeling roll 524 a provided on the upstream side of the conveyance path from the cooling device 523 is a roll for peeling plain paper from the fixing belt 527 in the same manner as the peeling roll 524. A guide member 525c provided on the opposite side of the cooling device 523 across the fixing belt 527 guides the plain paper peeled from the fixing belt 527 at the position of the peeling roll 524a between the guide member 525a and the guide member 525b. It is a member for doing. In this modification, the cooling device 523, the peeling roll 524, the steering roll 526, and the sensor 529 are rotated around the peeling roll 524a in the direction of arrow A or arrow B in the drawing.

  When the image forming mode is the low gloss mode, the control unit 10 sets the cooling device 523, the peeling roll 524, the sensor 529, and the steering roll 526 as arrows with the peeling roll 524a as the center as shown in FIG. The guide member 525c is moved by rotating in the B direction. Plain paper that has passed between the fixing roll 521 and the pressure roll 522 after the guide member 525c, the cooling device 523, the peeling roll 524, the sensor 529, and the steering roll 526 have moved to the positions shown in FIG. Is moved to the position of the peeling roll 524a together with the fixing belt 527, the plain paper is peeled from the fixing belt 527 at the position of the peeling roll 524a. The peeled plain paper passes between the guide member 525a and the guide member 525b without being cooled by the cooling device 523, and is discharged to the paper discharge tray 52 by the discharge rolls 528a and 528b.

  On the other hand, when the image forming mode is the high gloss mode, the control unit 10 moves the cooling device 523, the peeling roll 524, the sensor 529, and the steering roll 526 around the peeling roll 524a as shown in FIG. The guide member 525c is moved by rotating in the arrow A direction. After the guide member 525c, the cooling device 523, the peeling roll 524, the sensor 529, and the steering roll 526 move to the positions shown in FIG. 9A, the glossy paper moves while contacting the cooling device 523 together with the fixing belt 527. The fixing belt 527 and the glossy paper are cooled by the heat sink 523a. The glossy paper is peeled off from the fixing belt 527 at the position of the peeling roll 524. The peeled glossy paper passes between the guide member 525a and the guide member 525b, and is discharged to the paper discharge tray 52 by the discharge rolls 528a and 528b. Thus, in the present invention, the fixing belt 527 may not be cooled in the low gloss mode.

  In the image forming unit 3, the developing device may be a rotary developing device instead of a tandem type. In the case where the sheet is discharged from the side surface of the image forming apparatus, the fixing device 51 may be disposed not in the upper part of the image forming apparatus but in the vicinity of the sheet discharge port on the side surface of the image forming apparatus.

  The configuration for cooling the recording paper and the fixing belt 527 is not limited to the above-described embodiment. For example, the recording paper and the fixing belt 527 may be cooled by blowing air to the outer peripheral surface side of the fixing belt 527. Further, when a high gloss image is obtained without cooling the recording paper by the cooling device 523, the cooling device 523 may not be operated or the cooling device 523 may not be provided.

1 is a schematic diagram illustrating a configuration of an image forming apparatus according to an embodiment of the present invention. FIG. 2 is a diagram illustrating a configuration of a fixing device according to the embodiment. It is the figure which showed the structure which applies a load to a pressure roll. FIG. 6 is a diagram for explaining a region A and a region B of the fixing belt. FIG. 5 is a diagram illustrating a state of toner in a nip portion. 6 is a diagram illustrating operating conditions of the image forming apparatus. FIG. FIG. 7 is a diagram illustrating an image output result when the image forming apparatus is operated under the operation condition illustrated in FIG. 6. FIG. 10 is a diagram illustrating a configuration of a fixing device according to a modification. FIG. 10 is a diagram illustrating a configuration of a fixing device according to a modification.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 ... Control part, 51 ... Fixing device, 521 ... Fixing roll, 522 ... Pressure roll, 523 ... Cooling device, 524 ... Peeling roll, 526 ... Steering roll, 527: Fixing belt.

Claims (8)

A first roll;
A second roll facing the first roll across a conveyance path of the sheet to which the toner image is transferred;
A pressing means for pressing the first roll against the second roll with a first load or a second load larger than the first load;
An endless belt that has a first region and a second region, and is nipped in a nip portion between the first roll and the second roll and is moved around.
A sheet conveyed to the nip portion, and a heat source for heating the endless belt in the nip portion together with the sheet at a first temperature or a second temperature higher than the first temperature,
A cooling device that is on the downstream side of the conveyance path when viewed from the nip portion, and that cools the sheet attached to the endless belt by being heated and pressurized at the nip portion and passing through the nip portion,
When the image forming mode is the low gloss mode, the endless belt is moved so that the sheet passes through the nip portion together with the first region, and the heat source is the first temperature and the sheet and the endless belt. And the pressing means presses the first roll with a first load,
When the image forming mode is the high gloss mode, the endless belt is moved so that the sheet passes through the nip portion together with the second region, and the heat source is the second temperature and the sheet and the endless belt. And the pressing means presses the first roll with a second load.   The fixing device according to claim 1, further comprising: an adhesive member having adhesiveness; and a contact unit that causes the adhesive member to contact the second region.   The fixing device according to claim 1, wherein when the endless belt is stopped, the endless belt is moved so that the first region stops at the nip portion.   The fixing device according to claim 1, wherein a material of the first region is different from a material of the second region. The fixing device according to claim 1, wherein when the image forming mode is a high gloss mode, the cooling device cools the sheet to a temperature lower than that in the low gloss mode. When the image forming mode is the high gloss mode, the cooling device contacts the endless belt and cools the sheet via the endless belt,
The fixing device according to claim 5, wherein when the image forming mode is a low gloss mode, the cooling device is separated from the endless belt and does not cool the sheet.   The fixing device according to claim 1, wherein the sheet is resin-coated, and the second region is in contact with the resin-coated sheet.   An image forming apparatus comprising the fixing device according to claim 1.

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