JP2006243111A - Image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an image forming apparatus having a fixing device arranged at a position obtaining the optimum cleaning effect by the cleaning device of the inside face of a fixing belt. <P>SOLUTION: The image forming apparatus has a fixing device performing fixing treatment by stretching the fixing belt to a fixing sliding member and a belt drive roller to be rotated, and pushing a transfer material carrying a toner image by a pressuring means to the fixing sliding member or the belt drive roller through the fixing belt. The image forming apparatus is provided with a cleaning member on the downstream side of the fixing sliding member. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an image forming apparatus having a heat fixing device used for an electrophotographic system such as a copying machine, a printer, and a fax machine, and more particularly to an image forming apparatus having a heat fixing device using a fixing belt.

  A belt heating type fixing device used as a toner image fixing device in an image forming apparatus such as a copying machine or a printer will be described as an example.

  FIG. 5 is a schematic configuration diagram of one type of a conventional belt heating type fixing device.

In FIG. 5, 40 is an endless fixing belt made of nickel or heat-treated polyimide, and 41 is a heating roller that rotates by obtaining a driving force from a power source (not shown). A heater 47 is included.
Reference numeral 43 denotes a fixed sliding member in which a foamable urethane 412 is lined on an aluminum core 411 and an outer surface is covered with a coating of a fluororesin 413. Reference numeral 42 denotes a pressure roller, which has a mechanism capable of pressure-bonding and pressure-bonding to the fixed sliding member 43 via the fixing belt 40. Further, the pressure roller 42 can also be provided with residual heat by including a halogen heater 46. Reference numeral 44 denotes a tension roller.

  The fixing belt 40 is stretched around the heating roller 41, the fixed sliding member 43, and the tension roller 44, and is rotated by the power of the heating roller 41 so that the fixed sliding member 43 slides. Then rotate. The transfer material carrying the toner image is heated and pressed at a nip T formed by the fixing belt 40 and the pressure roller 42, and the toner image is fixed on the transfer material.

  When the fixing belt 40 has slid on the fixed sliding member 43 for a long time by such a mechanism, foreign matter such as abrasion powder such as fluorine resin of the fixed sliding member 43 is generated along with the sliding, There is a problem that the toner adheres to the inside of the fixing belt 40 and the fixing roller 41 and the fixing belt 40 slip to cause a belt conveyance failure or create a non-uniform heat distribution state on the belt to cause a fixing failure.

In order to avoid such a problem, for example, the cleaning brush 41A is rotatably supported at a predetermined angle on a rotating shaft of the heating roller 41 via a bearing (not shown), and wear powder on the inner surface of the fixing belt 40 is supported. And the like are attached to the heating roller 41 and further removed with a cleaning brush 41A (see, for example, Patent Document 1).
Japanese Patent Laid-Open No. 10-73125

  However, since only the surface of the drive roller is cleaned, it is conceivable that foreign matter remaining on the belt may cause inconveniences such as temperature unevenness and belt conveyance failure.

  An object of the present invention is to provide an image forming apparatus having a fixing device arranged at a position where the cleaning device for the inner surface of the fixing belt can obtain an optimum cleaning effect.

A fixing belt is stretched and rotated between a fixed sliding member and a belt driving roller, and a transfer material carrying a toner image is pressed onto the fixed sliding member or the belt driving roller via the fixing belt. An image forming apparatus having a fixing device that performs fixing processing by pressing with a cleaning member provided on the downstream side of the fixed sliding member.

  By improving the cleaning effect on the inner side surface of the fixing belt, it is possible to prevent the conveyance failure of the belt, avoid the uneven heat distribution state on the belt, and enable stable fixing.

  First, the entire image forming apparatus of the present embodiment will be described.

  In the description of the embodiment of the present invention, the technical scope of the present invention is not limited by the terms used in this specification.

  FIG. 1 is a schematic diagram illustrating an example of an image forming apparatus.

  In FIG. 1, the configuration will be described. 10 is a photoconductor, 11 is a scorotron charger as charging means, 12 is a writing device as image writing means, 13 is a developing device as developing means, and 14 is a photoconductor 10. A cleaning device for cleaning the surface, 15 a cleaning blade, 16 a developing sleeve, and 20 an intermediate transfer belt. The image forming unit 1 includes a photoconductor 10, a scorotron charger 11, a developing unit 13, a cleaning device 14, and the like. Since the mechanical configuration of the image forming unit 1 for each color is the same, in FIG. Reference numerals are given to configurations of only the (yellow) series, and reference symbols are omitted for the constituent elements of M (magenta), C (cyan), and K (black).

  The arrangement of the image forming means 1 for each color is in the order of Y, M, C, K with respect to the running direction of the intermediate transfer belt 20, and each photoconductor 10 contacts the stretched surface of the intermediate transfer belt 20. The contact point rotates in the same direction as the traveling direction of the intermediate transfer belt 20 and at the same linear speed.

  The intermediate transfer belt 20 is stretched around a driving roller 21, an earth roller 22, a tension roller 23, a static elimination roller 27, and a driven roller 24. The belt unit 3 includes these rollers, the intermediate transfer belt 20, a transfer device 25, a cleaning device 28, and the like. Configure.

  The intermediate transfer belt 20 is driven by rotation of the driving roller 21 by a driving motor (not shown).

  The photosensitive member 10 is formed by forming a photosensitive layer such as a conductive layer, an a-Si layer, or an organic photosensitive member (OPC) on the outer periphery of a cylindrical metal base formed of, for example, an aluminum material, and the conductive layer is grounded. In the state, it rotates counterclockwise as indicated by the arrow in FIG.

  An electrical signal corresponding to the image data from the reading device 80 is converted into an optical signal by the image forming laser, and is projected onto the photoconductor 10 by the writing device 12.

  The developing unit 13 is a developing sleeve formed of a cylindrical nonmagnetic stainless steel or aluminum material that keeps a predetermined interval with respect to the circumferential surface of the photoconductor 10 and rotates in the same direction as the rotation direction of the photoconductor 10. 16.

The intermediate transfer belt 20 is an endless belt having a volume resistivity of 10 ⁶ to 10 ¹² Ω · cm. For example, the intermediate transfer belt 20 may be an engineering plastic such as modified polyimide, thermosetting polyimide, ethylene tetrafluoroethylene copolymer, polyvinylidene fluoride, and nylon alloy. It is a semiconductive seamless belt having a thickness of 0.04 to 0.10 mm in which a conductive material is dispersed.

  A transfer unit 25 has a function of transferring a toner image formed on the photoreceptor 10 onto the intermediate transfer belt 20 by applying a direct current having a polarity opposite to that of the toner. As the transfer unit 25, a transfer roller can be used in addition to the corona discharger.

  Reference numeral 26 denotes a transfer roller which can be brought into contact with and released from the earth roller 22 and retransfers the toner image formed on the intermediate transfer belt 20 onto a transfer material P which is paper.

  A cleaning device 28 is provided to face the driven roller 24 with the intermediate transfer belt 20 interposed therebetween. After the toner image is transferred to the transfer material P, the intermediate transfer belt 20 has the charge of the residual toner weakened by the neutralizing roller 27 to which an AC voltage superimposed with a DC voltage having the same or opposite polarity as that of the toner is applied. The toner remaining on the peripheral surface is cleaned.

  7 is a transport path, 70 is a paper feed roller, 71 is a timing roller, 72 is a paper cassette, and 73 is a transport roller.

  81 is a paper discharge roller, and 85 is an operation panel. B1 is a control unit for the image forming process, transfer material conveyance, fixing temperature, and the like.

  Next, the fixing device according to the present invention will be described.

  A fixing device 4 fixes the toner image on the transfer material. The fixing device 4 includes a belt driving roller 41, a pressure roller 42 as a pressing unit, a fixing belt 40, and a fixing pad 43 as a fixed sliding member. The fixing pad 43 and the pressure roller 42 are pressed against each other via the fixing belt 40 to form a nip portion T, and the transfer material P carrying an unfixed toner image is passed through the nip portion T. Thus, the toner image is melted on the transfer material P by heating and pressing. The transfer material P on which the toner image is fixed is separated from the fixing belt 40 at the end of the nip portion T, proceeds along the fixing guide 44, and is discharged from the fixing discharge roller 45. Since the toner used here contains a wax, it is excellent in separation from the belt during the fixing process, so that it is not necessary to apply oil or the like.

  As shown in FIG. 2, the belt driving roller 41 has a cylindrical aluminum tube 431 covered with a release layer 432, and a halogen lamp 47 is disposed in the hollow for heating the belt. The pressure roller 42 is provided with a heat-resistant layer 422 of foamed silicone rubber as an elastic body on a cylindrical cored bar 423 made of aluminum, and a preheating heater 46 is provided in the hollow.

  FIG. 2 is an enlarged view of a main part of the fixing device in FIG.

  In FIG. 2, reference numeral 43 denotes a fixing pad which is a fixed sliding member, and the structure thereof is a fluororesin which is a heat-resistant film on which a foamable silicone sponge layer 412 is attached to an aluminum cored bar 411. 413 is stuck as a surface layer. By using the fixing pad 43, there is an advantage that a wide width of the nip portion T can be secured.

  As described above, when the fixing belt 40 slides on the fixed sliding member 43 for a long time, foreign matters such as fluorine resin abrasion powder are generated and adhere to the inside of the fixing belt 40, and the belt driving roller 41 and the fixing belt 40. This causes problems such as slippage of the belt and poor belt conveyance, or non-uniform heat distribution on the belt, leading to poor fixing.

  In order to avoid this problem, a belt conveyance failure can be avoided by arranging a cleaning device including a cleaning blade 451 for cleaning the inner surface of the fixing belt 40 and a tray 452 for the removed foreign matter.

  However, the cleaning effect greatly depends on the arrangement position of the cleaning device.

  The present invention is characterized in that an efficient cleaning effect can be obtained by arranging the cleaning device at an appropriate position.

  That is, in the present invention, the cleaning device 45 is disposed in the traveling direction of the fixing belt 40 and on the downstream side of the fixing pad 43. This is advantageous in that foreign matter such as abrasion powder of the fluororesin of the fixing pad 43 is removed before being sent to the heating roller 41, and it is on the tension side when viewed from the belt drive and is in a stronger tension state. There is an advantage that a more complete contact state can be maintained by bringing the cleaning blade 541 into contact with the inner surface.

  FIG. 3 is a diagram illustrating a main part of a fixing device of a type using an arc-shaped heat plate as a fixed sliding member.

  In FIG. 3, 48 is a heat plate which is a heating means. 41A is a belt drive roller, which is lined with silicone rubber 41C, which is an elastic layer, on the outer periphery of an iron cored bar 41B, and further coated with PFA resin on the outer periphery. To do. The other pressure rollers are the same as those shown in FIG.

  Next, the structure of the heat plate 48 based on FIG. 4 will be described.

  FIG. 4 is a sectional view of the heat plate.

  The heat plate 48 is made of a SUS foil (20 μm in this embodiment) carrying a heating electric resistor, an insulating layer PI (20 μm), an aluminum plate (0.8 mm) thereon, and a fluorine resin (20 μm). And generates heat when power is supplied from a power source.

  Returning to FIG. 3, the fixing belt 40 is heated by the heat plate 48, and a nip portion formed by press-contacting the belt driving roller 41 </ b> A and the pressure roller 42 as a pressure unit via the fixing belt 40. By passing the transfer material P carrying an unfixed toner image at T1, the toner image is melted onto the transfer material P by heating and pressurization. The transfer material P on which the toner image is fixed is separated from the fixing belt 40 at the end of the nip portion T1, is moved along the fixing guide 44 (see FIG. 1), and is discharged from the fixing discharge roller 45 (see FIG. 1). Is done.

  Even in this type of fixing device, the cleaning device 45 on the inner surface of the belt is disposed in the running direction of the fixing belt 40 and on the downstream side of the heat plate 48 which is a fixed sliding member. This has the advantage that foreign matter such as abrasion powder of fluororesin from the heat plate 48 is removed before being sent to the drive roller 41A and the heat plate 48, and is on the tension side when viewed from the belt drive. There is an advantage that a more complete contact state can be maintained by bringing the cleaning blade 451 into contact with the inner surface of the belt in a strong tension state.

  From the above, it is possible to perform a stable fixing process by disposing a cleaning device for the inner surface of the fixing belt at an optimal position.

1 is a schematic diagram illustrating an example of an image forming apparatus. FIG. 2 is an enlarged view of a main part of the fixing device in FIG. 1. It is a figure which shows the principal part of the fixing device of the type which used the circular arc-shaped heat plate for the fixed sliding member. It is sectional drawing of a heat plate. It is a schematic block diagram of one type of a conventional belt heating type fixing device.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Photoconductor 20 Intermediate transfer belt 4 Fixing device 40 Fixing belt 41, 41A Belt drive roller 42 Pressure roller 43 Fixing pad 451 Cleaning blade 46, 47 Halogen heater 48 Heat plate

Claims (3)

A fixing belt is stretched and rotated between a fixed sliding member and a belt driving roller, and a transfer material carrying a toner image is pressed onto the fixed sliding member or the belt driving roller via the fixing belt. An image forming apparatus having a fixing device that performs fixing processing by pressing with a cleaning member provided on the downstream side of the fixed sliding member. The image forming apparatus according to claim 1, wherein the fixed sliding member is a heat plate. The image forming apparatus according to claim 1, wherein the fixed sliding member is a fixing pad.

Images