JP2010282237A - Electrophotographic system fixing device and image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To extend the service life of a fixing device by stably and satisfactorily maintaining recording medium conveyance performance for a long time in the fixing device. <P>SOLUTION: The fixing device 50 includes a soft pad member 60 for applying pressure to a rotation member 52 via a fixing belt 54 inside the fixing belt 54 brought into contact with the rotation member 52, a pad member body 63 that has a locking piece 64 and supports the soft pad member 60, a low friction sheet member 66 that has an engaging hole 68 engaged with the locking piece 64 and is arranged between it and the fixing belt 54 by being wound on the pad member body 63 so as to cover the soft pad member 60, a lubricant applying member 78 for supplying a lubricant to an inner peripheral surface of the fixing belt 54, and a holder member 70 that has an escape groove 74A into which the locking piece 64 is loosely inserted, supports the pad member body 63 via an elastic sheet member 76, and supports the lubricant applying member 78 at the opposite side to the pad member body 63. The low friction sheet member 66 is formed of fabric having wefts and warps. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a fixing device used in a copying machine or a printer configured as an electrophotographic system, and an electrophotographic image forming apparatus using the fixing device.

  In general, in an image forming apparatus such as a copying machine or a printer using an electrophotographic system, for example, a photoconductor formed in a drum shape is uniformly charged, and the photoconductor is exposed with light controlled based on image information. Thus, an electrostatic latent image is formed on the photoreceptor. The electrostatic latent image is converted into a visible image (toner image) with toner, and the toner image is further transferred onto a recording paper (recording medium) and fixed by a fixing device to form an image.

  An electrophotographic image forming apparatus includes a color image forming apparatus that forms a full-color image. This color image forming apparatus is roughly classified into a type using an intermediate transfer member and a type not using an intermediate transfer member. The image forming apparatus using the intermediate transfer member temporarily transfers the toner image formed on the photosensitive member to the intermediate transfer member once, so that the primary transfer can be performed regardless of the material of the recording medium. This is advantageous for improving image quality.

  In addition, color image forming apparatuses using an intermediate transfer member include a so-called “4-cycle method” and a so-called “tandem method”. This four-cycle color image forming apparatus performs primary transfer in a state where toner images of respective colors such as yellow, magenta, cyan, and black, which are sequentially formed on a single photosensitive member, are superimposed on an intermediate transfer member. After that, the toner images of yellow, magenta, cyan, black, etc. transferred in multiple onto the intermediate transfer member are secondarily transferred onto a recording medium by a secondary transfer roll, thereby forming a color image.

  On the other hand, a “tandem type” color image forming apparatus uses toner images of different colors, such as yellow, magenta, cyan, and black, formed on a plurality of (for example, four) photosensitive members, as intermediate transfer members. After primary transfer in a state of being overlaid on each other, toner images of yellow, magenta, cyan, black, etc. transferred in multiple onto the intermediate transfer member are secondarily transferred onto a recording medium by a secondary transfer roll. Thus, a color image is formed.

  The fixing device used in the various types of image forming apparatuses as described above, for example, allows a recording paper carrying an unfixed toner image to pass between a fixing roll and a pressure roll, and for the unfixed toner image. Then, the toner image is fixed on the recording paper by heating and pressing.

  In such a fixing device for an electrophotographic system, the fixing speed can be increased, image quality can be improved by preventing the occurrence of fixing unevenness and paper wrinkles, the fixing device can be downsized, and the fixing device at room temperature can be fixed. It is desired to shorten the warm-up time until the state is brought up.

  Therefore, in order to answer this demand, a so-called free belt nip fuser (Free Belt Nip Fuser) has been put into practical use. This free belt nip fuser has a fixing surface in which the belt nip width is expanded and the exit side of the sheet is locally elastically deformed with respect to a fixing belt slidably disposed on the surface of a fixed pressure pad. The heat roll is configured to be press-contacted so as to be formed.

  The free belt nip fuser configured in this manner is used when a sheet on which a toner image has been transferred is nipped between a rotationally driven heat roll and a fixing belt, and is moved along with the fixing belt while passing through the fixing surface. Then, the toner image is fixed by heat and pressure bonding, and the sheet is peeled off from the fixing belt and carried out.

  This free belt nip fuser can widen the belt nip width, speed up the fixing process, reduce the size of the fixing device, and reduce the amount of heat taken from the heat roll to the fixing belt and pressure pad side. The amount of temperature drop at the nip portion can be reduced, the efficiency of using heat for melting the toner can be increased, and the toner fixability can be improved and the warm-up time can be shortened.

  Further, in such a free belt nip fuser, a sliding friction is reduced by providing a low friction layer with a small friction coefficient and wear resistance between the surface of the fixed pressure pad and the inner peripheral surface of the fixing belt. The thing is proposed (for example, refer patent document 1).

  Furthermore, in the free belt nip fuser, a lubricant is applied to the inner peripheral surface of the fixing belt to maintain good transportability of the recording medium passing between the heat roll and the fixing belt. It is desirable to replenish (supply) the lubricant to the sliding portion with the pressure to reduce the rubbing resistance (friction resistance) between the pressure pad and the fixing belt.

  However, since pressure is applied between the pressure pad and the fixing belt, when a relatively large amount of lubricant is applied to the inner peripheral surface of the fixing belt, a part of the lubricant is reduced in friction with the fixing belt. The lubricant that cannot enter the sliding portion between the layers gradually accumulates in the entrance region of the sliding portion. As the fixing belt repeatedly rotates, the accumulated lubricant spreads to both ends in the sliding portion entrance region, leaks to the outside, and adheres to the recording medium. Due to the leakage of the lubricant, the amount of lubricant applied to the inner peripheral surface of the fixing belt gradually decreases. Therefore, there is a tendency that the slipping property between the low friction layer and the fixing belt gradually decreases. Further, the wear of the low friction layer and the fixing belt advances due to the decrease in the amount of the lubricant, and the slipping property between the low friction layer and the fixing belt may further decrease.

  Under such circumstances, when the fixing process is performed with the fixing device, the frictional resistance between the pressure pad and the fixing belt increases, and slipping between the fixing belt and the recording medium causes the heat roll and the fixing belt to There is a problem that the transportability of the recording medium passing between the two is not good, and the possibility of causing wrinkling and jamming in the recording medium is increased.

Japanese Patent Application Laid-Open No. 11-133776

  SUMMARY OF THE INVENTION In view of the above-described problems, the present invention provides a fixing device for an electrophotographic system and an image formation that can stably and satisfactorily maintain the recording medium conveyance performance in the fixing device over a long period of time and extend the service life of the fixing device. An object is to newly provide a device.

  The fixing device for an electrophotographic system according to claim 1 is a fixing device for fixing a toner image carried on a recording medium, the surface of which is elastically deformed, and a rotational member that is rotationally driven. A fixing belt formed in an endless belt shape that is in contact with the moving member; and a predetermined pressure applied to the rotating member by pressing the rotating member inside the fixing belt via the fixing belt. A soft pad member for applying a protrusion and a locking piece projecting in a protruding shape at each of a plurality of positions on a straight line along the longitudinal direction, and is located inside the fixing belt and supports the soft pad member A pad member main body and a plurality of engaging holes into which the plurality of locking pieces are inserted and engaged, respectively, are wound around the pad member main body so as to cover the soft pad member. A low-friction sheet member disposed so as to face the belt, a lubricant application member that replenishes the lubricant by sliding contact with the inner peripheral surface of the fixing belt, and a clearance groove for loosely inserting the locking piece. And a holder member that supports the lubricant application member on the opposite side of the pad member main body and supports the pad member main body via an elastic sheet member, and the low friction sheet member includes a weft And is composed of a fabric made of warp.

  According to the first aspect of the present invention, the pressure generated in the low friction sheet member during fixing can be made uniform over a long period of time. Further, in a state where pressure is uniformly secured, the lubricant can be surely entered between the soft pad member and the fixing belt by the unevenness of the gap between the fabrics formed by the weft and the warp. Therefore, even with a smaller amount of lubricant, the inner peripheral surface of the fixing belt can smoothly slide on the low friction sheet member, reducing wear and stabilizing the recording medium conveyance performance in the fixing device over a long period of time. It can be maintained well and the service life of the fixing device can be extended.

  An image forming apparatus according to a second aspect includes the fixing device according to the first aspect.

  According to the fixing device and the image forming apparatus for the electrophotographic system of the present invention, the recording medium conveyance performance in the fixing device can be stably and satisfactorily maintained for a long period of time, and the service life of the fixing device can be extended. There is.

1 is a schematic longitudinal sectional view of an image forming apparatus according to an embodiment of the present invention. FIG. 3 is a partial cross-sectional perspective view showing a main part of a fixing device used in the image forming apparatus according to the embodiment of the present invention. 1 is an exploded perspective view of a fixing device used in an image forming apparatus according to an embodiment of the present invention. 1 is an exploded perspective view of a main part of a fixing device used in an image forming apparatus according to an embodiment of the present invention. FIG. 3 is a plan view showing a low friction sheet member of a fixing device used in the image forming apparatus according to the embodiment of the present invention. 6 is a table showing experimental results related to lubricant viscosity (oil viscosity) and lubricant leakage (oil leakage) performed on a fixing device used in the image forming apparatus according to the embodiment of the present invention. 6 is a table showing experimental results relating to the surface roughness of the inner peripheral surface of the fixing belt and leakage of lubricant (oil leakage), which was performed on the fixing device used in the image forming apparatus according to the embodiment of the present invention.

  DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments relating to a fixing device and an image forming apparatus for an electrophotographic system of the present invention will be described with reference to FIGS.

  A four-cycle full-color printer as an image forming apparatus provided with a fixing device for an electrophotographic system according to the present embodiment is shown in a diagram inside the full-color printer main body 10 as shown in the schematic cross-sectional configuration diagram of FIG. A photosensitive drum 12 serving as an image carrier is rotatably arranged at an upper right part slightly toward the center. The photosensitive drum 12 is composed of, for example, a conductive cylinder having a diameter of about 47 mm and having a surface coated with a photosensitive layer made of OPC or the like, and is about 150 mm / second along the direction of arrow A by a driving means (not shown). Driven at a process speed of sec.

  The surface of the photosensitive drum 12 is charged to a predetermined potential by rolling contact with a charging roll 14 as a charging unit. After that, image exposure with a laser beam (LB) is performed by a ROS 16 (Raster Output Scanner) as exposure means arranged at a position directly below the photosensitive drum 12, and an electrostatic latent image corresponding to the image information is generated. It is formed.

  The electrostatic latent image formed on the surface of the photoconductive drum 12 passes through the developing devices 15Y, 15M, 15C, and 15K for each color of yellow (Y), magenta (M), cyan (C), and black (K). The toner is developed by a rotary developing device 15 arranged along the direction, and becomes a toner image of a predetermined color. At this time, on the surface of the photosensitive drum 12, the charging, exposure, and development processes are repeated a predetermined number of times according to the color of the image to be formed.

  The rotary developing device 15 is rotationally driven at a predetermined timing, and the developing devices 15Y, 15M, 15C, and 15K corresponding to the color to be developed move to a developing position facing the photosensitive drum 12. For example, in the case of forming a full-color image, the charging, exposure, and development processes on the surface of the photosensitive drum 12 are yellow (Y), magenta (M), cyan (C), and black (K). Repeated four times for each color. A toner image corresponding to each color of yellow (Y), magenta (M), cyan (C), and black (K) is sequentially formed on the surface of the photosensitive drum 12.

  The number of rotations of the photosensitive drum 12 when a toner image is formed in this manner varies depending on the size of the image. For example, in the case of an A4 size, the photosensitive drum 12 is used to form a single color image. Rotates 3 times. In other words, each time the photosensitive drum 12 rotates three times, toner images corresponding to yellow (Y), magenta (M), cyan (C), and black (K) colors are sequentially formed on the surface of the photosensitive drum 12. It is formed. The toner images sequentially formed on the photosensitive drum 12 are primarily transferred in a state of being superimposed on the intermediate transfer belt 18 when passing through the primary transfer position.

  The yellow (Y), magenta (M), cyan (C), and black (K) toner images sequentially formed on the photosensitive drum 12 are belt-shaped image carriers on the outer periphery of the photosensitive drum 12. At the primary transfer position where the intermediate transfer belt 18 as an (intermediate transfer body) is wound, the primary transfer is performed by the primary transfer roll 20 while being superimposed on the intermediate transfer belt 18. The yellow (Y), magenta (M), cyan (C), and black (K) toner images transferred in multiple onto the intermediate transfer belt 18 are fed by the secondary transfer roll 22 at a predetermined timing. Secondary transfer is performed collectively on a recording sheet 24 as a recording medium.

  The secondary transfer roll 22 is rotationally driven via a gear from a driving source (not shown). The recording paper 24 is fed by a pickup roll 28 from a paper feeding unit 26 disposed at the lower part of the full-color printer main body 10 and is fed in a state where it is rolled one by one by a feed roll 30 and a retard roll 32. The toner image is transferred to the secondary transfer position of the intermediate transfer belt 18 in synchronization with the toner image transferred onto the intermediate transfer belt 18 by the registration roll 34. The secondary transfer roll 22 is configured to come in contact with and separate from the surface of the intermediate transfer belt 18 at a predetermined timing.

  The intermediate transfer belt 18 is stretched by a plurality of rolls, and is configured to rotate at a predetermined process speed (about 150 mm / sec) synchronized with the rotation of the photosensitive drum 12. That is, the intermediate transfer belt 18 intermediates a wrap-in roll 36 that specifies the wrap position of the intermediate transfer belt 18 on the upstream side in the rotational direction of the photosensitive drum 12 and a toner image formed on the photosensitive drum 12. The primary transfer roll 20 to be transferred onto the transfer belt 18, the lapped roll 38 for specifying the wrap position of the intermediate transfer belt 18 on the downstream side of the wrap position, and the secondary transfer roll 22 are in contact with each other via the intermediate transfer belt 18. The backup roll 40, the first cleaning backup roll 44 facing the cleaning device 42 of the intermediate transfer belt 18 and the second cleaning backup roll 46 are stretched with a predetermined tension.

  Further, in the full-color printer main body 10, in order to improve the maintainability of the intermediate transfer belt 18 and the rotary developing device 15 that occupies a large space while achieving the downsizing of the apparatus, the intermediate transfer belt 18 is not photosensitive. The image forming unit 48 including the body drum 12, the charging roll 14, and the secondary transfer roll 22 is integrally configured. By opening the upper cover portion of the full-color printer main body 10, the entire image forming unit 48 is configured. The image forming unit 48 is detachable so that it can be taken out of the full-color printer main body 10.

  Further, the cleaning device 42 for the intermediate transfer belt 18 includes a scraper and a cleaning brush (not shown) that are mounted so as to be movable so as to rub against the surface of the intermediate transfer belt 18 from a separated position at a necessary timing. . Residual toner and paper dust removed by these scrapers and cleaning brushes are collected inside the cleaning device 42.

  In this full-color printer, the surface of the photosensitive drum 12 after the toner image transfer process is completed is disposed at a position obliquely below the photosensitive drum 12 every time the photosensitive drum 12 rotates once. Residual toner and the like are removed by a cleaning blade 35 so as to prepare for the next image forming process.

  The recording paper 24 onto which the toner image has been transferred from the intermediate transfer belt 18 as described above is conveyed to the fixing device 50 and pressed under heat to fix the toner image on the recording paper 24.

(Fixing device)
As shown in FIGS. 1 to 4, the fixing device 50 is configured as a so-called free belt nip fuser (free belt nip fuser) system, and includes a heat roll 52 as a rotationally driven rotating member, and the heat roll A main part is constituted by a pressure pad 56 which is a pressure member 52 in pressure contact with the fixing belt 54.

  Although not shown, the heat roll 52 is configured by laminating a heat-resistant elastic body layer and a release layer around a metal core (cylindrical cored bar) formed in a cylindrical shape having a predetermined length. The core of the heat roll 52 is composed of a cylindrical body made of a metal having high thermal conductivity such as iron, aluminum, SUS, etc. (here, a thin high-tensile steel pipe is used). The outer shape and thickness of the core can be reduced in diameter and thickness because the pressing force of the pressure pad 56 in the fixing device 50 is small.

  Further, any material can be used for the heat-resistant elastic layer in the heat roll 52 as long as it is an elastic body having high heat resistance. In particular, it is preferable to use an elastic body such as rubber or elastomer having a rubber hardness of about 25 to 40 degrees (JIS A). Specifically, silicone rubber, fluorine rubber, or the like can be used.

  The release layer in the heat roll 52 may be any resin as long as it is a heat-resistant resin. For example, a silicone resin, a fluorine resin, or the like can be used. From the viewpoint of wear resistance, fluorine resin is suitable. As the fluororesin, PFA, PTFE (polytetrafluoroethylene), FEP (tetrafluoroethylene hexafluoropropylene copolymer), or the like can be used. The thickness of the release layer is preferably 10 to 50 μm, more preferably 10 to 30 μm. If the thickness of the release layer is less than 10 μm, the recording paper 24 tends to be wrinkled based on the distortion of the heat roll 52, while if it exceeds 30 μm, the release layer becomes hard and the image has defects such as uneven gloss. This is because the possibility of occurrence increases and both are not preferable.

  Inside the heat roll 52, a halogen lamp is disposed as a heat source. A temperature sensor is brought into contact with the surface of the heat roll 52, and the control unit of the image forming apparatus controls lighting of the halogen lamp based on a temperature measurement value by the temperature sensor. It adjusts so that preset temperature (for example, 170 degreeC) may be maintained.

  A fixing belt (formed in an endless belt shape) 54 that rotates in synchronization with the heat roll 52 while being in pressure contact is formed in an endless track shape (cylindrical shape of a predetermined length).

  The fixing belt 54 is configured in an endless belt shape (endless belt), and includes a base layer and a release layer coated on the surface or both surfaces of the base layer on the heat roll 52 side. The base layer is formed of a polymer such as polyimide, polyamide, or polyimideamide, or a metal such as SUS, nickel, or copper, and has a thickness of 30 to 200 μm, preferably 50 to 125 μm, and more preferably about 75 to 100 μm. The release layer coated on the surface of the base layer is formed of a fluororesin such as PFA, PTFE, or FEP, and has a thickness of about 5 to 100 μm, preferably about 10 to 30 μm.

  Further, the inner peripheral surface of the fixing belt 54 has a surface roughness Ra (arithmetic average roughness) of 0.5 μm which is a so-called mirror finish in order to reduce the frictional resistance with the low friction sheet member 66 on the pressure pad 56. Below. Further, the outer peripheral surface of the fixing belt 54 is set to have a surface roughness Ra of 1.2 to 2.0 μm so that the driving force from the heat roll 52 is easily received. That is, the fixing belt 54 is configured such that the friction coefficient of the inner peripheral surface is smaller than the friction coefficient of the outer peripheral surface.

  Thereby, in the fixing device 50, as will be described later, the heat roll 52 is rotationally driven to convey the recording paper 24 nipped in the nip portion, and at the same time, interlocked with the rotation operation of the heat roll 52 via the recording paper 24. The fixing belt 54 is rotated without slipping. During this operation, in the fixing device 50, the outer peripheral surface of the fixing belt 54 is brought into contact with the recording paper 24 or the heat roll 52 so as not to slip, and the inner peripheral surface of the fixing belt 54 covers the pressure pad 56 with low friction. The sheet member 66 slides smoothly on the sheet member 66.

  Further, the fixing belt 54 is configured such that the hardness of the inner peripheral surface thereof is greater than the hardness of the surface of the low friction sheet member 66. With this configuration, since the hardness of the inner peripheral surface of the fixing belt 54 is equal to or higher than the hardness of the surface of the low friction sheet member 66, the inner peripheral surface of the fixing belt 54 is placed on the low friction sheet member 66 as will be described later. When sliding, the amount of wear of the fixing belt 54 can be made smaller than the amount of wear of the low friction sheet member 66. With this configuration, the wear of the fixing belt 54 can be delayed and the service life of the fixing belt 54 can be extended.

  The fixing belt 54 (formed in an endless belt shape) is slidably slidably contacted with the low friction sheet member 66 on the pressure pad 56 slidably contacting the inner peripheral surface of the fixing belt 54 and both inner peripheral surface portions of the fixing belt 54. Guided by the respective edge guides 58, it is supported so as to be rotatable (circularly movable). The fixing belt 54 is attached so that the nip portion corresponding to the pressure pad 56 is brought into rolling contact with the heat roll 52 with a predetermined pressure.

  The pressure pad 56 is inside the fixing belt 54, presses the heat roll 52 with a predetermined pressure distribution via the fixing belt 54, and forms a nip portion with the heat roll 52. Here, the nip portion is a region where the fixing belt 54 and the heat roll 52 are in rolling contact with each other while being elastically deformed, and has a predetermined length in the rotation direction of the fixing belt 54 and the heat roll 52 (the conveyance direction of the recording paper 24). A region having a rectangular shape in the plan view extending in the longitudinal direction of the fixing belt 54 and the heat roll 52.

  The pressure pad 56 includes a soft pad member 60 serving as a pressure member and a hard pad member 62 also serving as a pressure member. The soft pad member 60 is disposed on the entrance side of the nip portion in the conveyance direction, secures a wide nip portion with respect to the conveyance direction of the recording paper 24 as a recording medium, and is heated so that the recording paper 24 reaches a predetermined temperature. However, it is configured so that the required pressure can be applied. For example, the soft pad member 60 can be made of an elastic material such as silicone rubber or fluorine rubber, or a leaf spring.

  In this full-color printer, as shown in FIG. 3, the soft pad member 60 is configured by adhering an auxiliary member 60B formed of a metal long plate material to the bottom surface of an elastic material 60A formed in a prismatic shape. The upper surface of the elastic material 60 </ b> A is formed in a concave shape that substantially follows the outer peripheral surface of the heat roll 52.

  The hard pad member 62 of the pressure pad 56 is disposed on the exit side in the conveyance direction of the nip portion, and is strongly pressed against the heat roll 52 to elastically deform the heat-resistant elastic body layer and the release layer provided around the core. The recording paper 24 is peeled off from the surface of the heat roll 52.

  The hard pad member 62 can be formed using, for example, a heat-resistant resin such as PPS (polyphenylene sulfide), polyimide, polyester, or polyamide, or a metal such as iron, aluminum, or SUS. The shape of the hard pad member 62 is formed in a convex curved surface shape (so-called saddle shape) in which the outer surface shape at the nip portion has a constant radius of curvature.

  As shown in FIG. 3, the hard pad member 62 integrally forms an installation portion 62A of the soft pad member 60 adjacent to the upstream side in the transport direction along the longitudinal direction. That is, the hard pad member 62 is formed in a part of the rectangular elongated pad member main body 63, and the installation portion 62A of the rectangular groove-shaped soft pad member 60 is formed in a position adjacent to the hard pad member 62.

  Then, the soft pad member 60 is fitted into the installation portion 62A so as to be integrally assembled with the installation portion 62A on the bottom side. Thereby, the soft pad member 60 and the hard pad member 62 constitute one pressure pad 56 adjacent to each other in the longitudinal direction.

  In addition, a low friction sheet member 66 that is a rubbing member is engaged with the upstream end portion of the recording sheet 24 in the conveyance direction on the bottom surface of the pad member main body 63 at a plurality of positions spaced apart from each other in the longitudinal direction. A small rectangular protruding piece-like locking piece 64 for wearing is protruded.

  As shown in FIGS. 2, 3 and 5, the low friction sheet member 66 is disposed so as to sufficiently cover the surface of the soft pad member 60 and the hard pad member 62 in the pressure pad 56 corresponding to the nip portion. To do. The low friction sheet member 66 reduces the frictional resistance (friction resistance) when the pressure pad 56 is in sliding contact with the inner peripheral surface of the fixing belt 54 through the low friction sheet member 66 in a state where a strong pressure is applied. For example, a sheet having a small friction coefficient and excellent wear resistance and heat resistance (for example, a sheet made of a porous fluororesin fabric) is formed into a rectangular shape as shown in FIG. .

  Further, minute unevenness is formed on the surface of the low friction sheet member 66 on the fixing belt 54 side so that the lubricant applied to the inner peripheral surface of the fixing belt 54 can enter the sliding portion with the fixing belt 54. ing. For example, the roughness of the unevenness is formed such that Ra (arithmetic average roughness) is 5 to 30 μm. This is not appropriate if the roughness of the unevenness is less than Ra = 5 μm, because it is difficult to allow sufficient lubricant to enter the sliding portion with the fixing belt 54, while if it is greater than Ra = 30 μm, the unevenness is not suitable. This is based on the fact that the mark is not preferable because it is noticeable as uneven gloss when OHP or coated paper is fixed.

  As described above, in this fixing device 50, the surface roughness Ra of the outer peripheral surface of the fixing belt 54 is larger than the surface roughness Ra of the inner peripheral surface of the fixing belt 54, and the surface roughness of the outer peripheral surface of the fixing belt 54 together with this. The surface roughness Ra of the low friction sheet member 66 is configured to be larger than Ra.

  That is, with this configuration, the frictional resistance on the outer peripheral surface side of the fixing belt 54 exceeds the frictional resistance on the inner peripheral surface side, so that the recording paper 24 is rotated by the heat roll 52 that rotationally drives the fixing belt 54. Can be rotated in synchronism with the transporting operation, and the fixing process for the recording paper 24 can be stably executed. The state in which an appropriate amount of lubricant is applied to the inner peripheral surface of the fixing belt 54 can be maintained, and the fixing belt 54 can appropriately rotate without slipping.

  Further, the low friction sheet member 66 is configured so as not to be infiltrated into the lubricant (difficult to pass through) so that the lubricant does not penetrate and leak from the back surface. Further, the low friction sheet member 66 includes a porous resin fiber cloth made of fluororesin as a base layer and a PET resin sheet wrapped around the surface of the heat roll 52, a sintered PTFE resin sheet, Teflon (registered) A glass fiber sheet impregnated with (trademark) can be used.

  The low friction sheet member 66 is provided with a locking hole 68 at each position corresponding to each locking piece 64 near one end in the longitudinal direction. One end of the low friction sheet member 66 in the longitudinal direction is continuous in a straight line, and a part thereof is not provided with a notch or a recess. Further, when the low friction sheet member 66 is made of a woven fabric, the direction in which one thread (weft or warp) woven in the woven fabric is aligned with the longitudinal direction of the low friction sheet member 66. It is desirable to be able to receive a load in a direction perpendicular to the entire length of the yarn.

  The engagement hole 68 formed in the low friction sheet member 66 is formed in a through hole surrounded by a smooth curve that is a semicircular straight circle or an ellipse or a shape having no corners or notches at both ends, and stress concentration. To avoid breaking. Further, in this low friction sheet member 66, the distance from each engagement hole 68 to one end portion in the longitudinal direction of the low friction sheet member is increased by a required amount so that the low friction sheet member 66 is engaged with the engagement hole 68. The reinforcing structure is such that it does not break from the portion to one end in the longitudinal direction. The low friction sheet member 66 is provided with a reinforcing structure such as increasing the thickness or stacking two sheets in a portion from each engaging hole 68 portion to one end portion in the longitudinal direction of the low friction sheet member. It may be provided.

  The low friction sheet member 66 is mounted so that the corresponding locking piece 64 of the pad member main body 63 is inserted into each engaging hole 68 and wound from the soft pad member 60 to the hard pad member 62. The low friction sheet member 66 mounted on the pad member main body 63 in this way is provided with a locking hole 68 for the low friction sheet member 66 when the pad member main body 63 is mounted in the mounting portion 74 as will be described later. The portion near one end in the longitudinal direction is engaged with an engagement structure in which a required pressure is applied between the vertical wall of the escape groove 74A and the vertical wall of the pad member main body 63, and the low friction sheet member It may be configured so that the load is not concentrated only on the engaging holes 68 of 66.

  The pad member main body 63 in which the soft pad member 60 and the low friction sheet member 66 are assembled in this way is attached to the holder member 70.

  As shown in FIGS. 2 to 4, the holder member 70 is made of a metal such as aluminum, and is formed in a deformed cylindrical shape in which one corner of a substantially rectangular cross section is projected in a small arc shape.

  The holder member 70 is installed with a guide corner 72 protruding in the shape of a small arc facing the upstream side in the conveyance direction of the recording paper 24, and the outer peripheral surface of the guide corner 72 is the inner side of the fixing belt 54. It slides on the peripheral surface and guides its circular motion.

  In addition, the holder member 70 forms a mounting portion 74 such as a pad member main body 63 on a side surface portion adjacent to the guide corner portion 72. The mounting portion 74 is formed in a rectangular shallow groove shape, and a clearance groove 74 </ b> A for loosely inserting the locking piece 64 is formed so as to be adjacent along the guide corner portion 72.

  An elastic sheet member 76 is disposed on the mounting plane of the mounting portion 74 (a plane excluding the clearance groove 74A on the bottom surface of the mounting portion 74). The elastic sheet member 76 is formed of an elastic material having heat resistance such as a heat resistant rubber material. The elastic sheet member 76 is an elastic material having excellent heat resistance that can withstand heat of about 100 ° C. without absorbing oil and expanding. The elastic sheet member 76 has elasticity having a rubber hardness of about 30 degrees (JIS A). Depending on the material, it is formed into a long plate shape (band shape).

  The elastic sheet member 76 has the same shape as the mounting plane of the mounting portion 74, has a constant thickness, and is disposed on the mounting plane of the mounting portion 74.

  Further, the elastic sheet member 76 may be disposed corresponding to a portion where the hard pad member 62 receives pressure locally. In this case, the elastic sheet member 76 is formed as a single member or a plurality of members having a shape corresponding to a portion where the hard pad member 62 receives pressure locally, and each member is a hard surface on the mounting plane of the mounting portion 74. The pad member 62 is disposed in a portion that receives pressure locally.

  Further, the elastic sheet member 76 may be disposed only on the bottom surface portion immediately below the hard pad member 62 on the mounting plane of the mounting portion 74. Alternatively, the elastic sheet member 76 may be disposed only on the bottom surface portion directly below the hard pad member 62 and the soft pad member 60 on the mounting plane of the mounting portion 74. The elastic sheet member 76 may be disposed over the entire surface of the attachment portion 74.

  As shown in FIGS. 2 to 4, the holder member 70 is provided with a lubricant application member 78 on the outer side surface 79 of the side facing the mounting portion 74 in the longitudinal direction. The lubricant application member 78 is formed of a belt-like heat-resistant felt, and is impregnated with, for example, about 3 g of a lubricant such as amino-modified silicone oil having a viscosity of 300 cs having excellent affinity. The lubricant application member 78 is disposed so as to be in sliding contact with the inner peripheral surface of the fixing belt 54, and always replenishes the inner peripheral surface of the fixing belt 54 with an appropriate amount of lubricant by the osmotic pressure from the heat-resistant felt. It is configured as follows. In addition, it is desirable that the lubricant application member 78 is such that only the edge portion of the heat resistant felt is brought into contact with the inner peripheral surface of the fixing belt 54 so that the lubricant is not replenished excessively from the heat resistant felt. Thereby, the lubricant is supplied to the sliding portion between the fixing belt 54 and the low friction sheet member 66, and the friction resistance between the fixing belt 54 and the pressure pad 56 via the low friction sheet member 66 is further reduced, A smooth operation of the fixing belt 54 is achieved.

  Further, in the fixing device 50, a lubricant (lubricant) having an appropriate viscosity is supplied to the fixing belt 54 so that smooth operation can be performed by always supplying an appropriate amount of lubricant from the lubricant applying member 78 to the inner peripheral surface of the fixing belt 54. Select oil to use. This is because when the viscosity of the lubricant is too low, the lubricant easily leaks, and when the viscosity of the lubricant is too high, the friction increases and the slidability of the fixing belt 54 decreases.

  In this way, the fixing belt 54 that slides on the pressure pad 56 is supported by the respective edge guides 58 so that the inner peripheral surface portions at both ends can be freely rotated (rotated freely). The edge guide 58 is provided outside the belt traveling guide member 59 having a substantially C-shaped cross section. Further, the belt traveling guide member 59 is formed of a material having a low coefficient of static friction and a low thermal conductivity in order to reduce the frictional resistance as much as possible and to reduce heat loss. Further, the belt travel guide member 59 is formed with a flange portion 61 projecting outside the edge guide 58 so as to protrude larger than the inner diameter of the fixing belt 54.

  Each belt traveling guide member 59 is fastened to both ends of the holder member 70 by fitting the screw parts 67 into the screw holes 65 provided in the cylindrical holes of the holder member 70, respectively.

  Further, in the fixing device 50, the interval between the inner surfaces of the flange portions 61 of the belt traveling guide member 59 attached to both ends of the holder member 70 is set so as to substantially match the width of the fixing belt 54. The movement (belt walk) of the fixing belt 54 in the width direction is restricted.

  Next, a basic image forming process of a full color printer which is an image forming apparatus provided with a fixing device for an electrophotographic system according to the present embodiment will be described.

  In a full-color printer as shown in FIG. 1, image data output from an image reading device (IIT) not shown or a personal computer (PC) not shown is subjected to predetermined image processing by an image processing device (IPS) not shown. After that, the image forming operation is executed by the developing device 15 (15Y, 15M, 15C, 15K). In this image processing apparatus (IPS), the input reflectance data is subjected to various image editing operations such as shading correction, position shift correction, brightness / color space conversion, gamma correction, frame deletion, color editing, and moving editing. Predetermined image processing is performed. The image data that has been subjected to image processing is converted into color material gradation data of four colors Y, M, C, and K, and is output to the ROS 16 that is a laser exposure device.

  The ROS 16 irradiates the photosensitive drum 12 of the developing device 15 with, for example, a laser beam LB emitted from a semiconductor laser in accordance with the input color material gradation data. In the developing device 15, after the surface is charged by the charging roll 14, the surface is scanned and exposed by the ROS 16 to form an electrostatic latent image.

  The electrostatic latent image formed on the surface of the photoconductive drum 12 passes through the developing devices 15Y, 15M, 15C, and 15K for each color of yellow (Y), magenta (M), cyan (C), and black (K). The toner is developed by a rotary developing device 15 arranged along the direction, and toner images corresponding to yellow (Y), magenta (M), cyan (C), and black (K) are sequentially formed. The toner images sequentially formed on the photosensitive drum 12 in this manner are primarily transferred in a state of being superimposed on the intermediate transfer belt 18 when passing through the primary transfer position.

  Then, the yellow (Y), magenta (M), cyan (C), and black (K) toner images transferred in multiple onto the intermediate transfer belt 18 are recorded on a recording sheet as a recording medium by the secondary transfer roll 22. Secondary transfer is performed on 24 at once.

  The recording paper 24 onto which the toner image has been transferred from the intermediate transfer belt 18 in this way is carried into the fixing device 50.

  In the fixing device 50, the heat roll 52 is rotated in the direction of arrow B by a drive motor (not shown), and the fixing belt 54 is also driven to rotate by this rotation, and the recording paper 24 on which the toner image is electrostatically transferred is transferred to the heat roll 52. And the pressure pad 56 are carried into a nip portion. When the recording paper 24 passes through the nip portion, the toner image on the recording paper 24 is fixed by the pressure acting on the nip portion and the heat supplied from the heat roll 52.

  In this fixing device 50, the nip portion can be broadly configured by the concave soft pad member 60 that substantially follows the outer peripheral surface of the heat roll 52, so that stable fixing performance can be ensured. In addition to this, in the fixing device 50, the hard pad member 62 protruded so as to bite into the outer peripheral surface of the heat roll 52 causes distortion of the surface layer of the heat roll 52 in the exit region (peeling nip portion) of the nip portion. Therefore, when the recording paper 24 after the fixing process passes through the peeling nip portion, the recording paper 24 passes through the locally formed distortion, and is reliably peeled without being wound around the heat roll 52. Is done. That is, it is possible to locally increase the distortion of the heat roll 52 by the hard pad member 62 and obtain high peeling performance with a small distortion amount. Therefore, even when a thin heat-resistant resin is used as the release layer of the heat roll 52, the occurrence of paper wrinkles on the recording paper 24 can be suppressed. Further, peeling between the heat-resistant elastic body layer and the release layer hardly occurs, and the reliability of the component performance over a long period can be improved together with the maintenance of the peeling performance.

  Furthermore, since the distortion amount of the heat roll 52 can be formed small, the heat roll 52 can thin its heat-resistant elastic layer. Therefore, since the heat capacity of the heat roll 52 can be reduced, the warm-up time can be shortened and the power consumption can be reduced. In addition, since the heat-resistant elastic layer having a low thermal conductivity can be thinned, the thermal resistance between the inner surface and the outer surface of the heat roll 52 is reduced and the thermal response can be improved. Also suitable for.

  In the fixing device 50 according to the present embodiment, the pad member main body 63 is attached to the attachment portion 74 of the holder member 70 via the elastic sheet member 76. Therefore, in the fixing device 50, when a strong load is locally applied to the hard pad member 62, the hard pad member 62 in the pad member main body 63 is locally elastically deformed at a portion where the strong load is applied. (The elastic sheet member 76 is deformed so as to be locally bent so as to be crushed) and dispersed so that the load is not concentrated.

  That is, when the fixing device 50 fixes a locally thick recording medium (for example, an envelope), the locally thick part of the recording medium is located between the heat roll 52 and the hard pad member 62. When passing through the nip portion of the position, a large load is applied to a place where a locally thick portion of the recording medium is placed on the hard pad member 62. Then, the hard pad member 62 is elastically deformed so as to be locally bent so as to be recessed away from the heat roll 52 while elastically deforming the elastic sheet member 76 at a portion where a large load is applied, and escapes. For this reason, the hard pad member 62 is subjected to an average load over the entire length of the portion to which the load in the longitudinal direction is applied, and the distribution of the load in the longitudinal direction on the hard pad member 62 is allowed. Within the range, appropriate fixing processing (for example, fixing processing without wrinkles on the recording paper 24 or wrinkles due to plastic deformation on the surface of the heat roll 52) can be performed. In the fixing device 50, when the elastic sheet member 76 is not pulled between the mounting portion 74 of the holder member 70 and the hard pad member 62, there is no room for the hard pad member 62 to be elastically deformed. A local load is applied to the side 52, and the recording paper 24 is likely to wrinkle, or the surface of the heat roll 52 is likely to wrinkle due to plastic deformation.

  In the fixing device 50, as described above, the recording paper 24 on which the toner image has been electrostatically transferred passes through the nip portion, whereby the toner image is fixed on the recording paper 24. The conveying force at the time of passing is received from the heat roll 52 on the driving side. That is, the recording paper 24 is conveyed by receiving a frictional force from the heat roll 52 as the heat roll 52 rotates. Therefore, when the recording paper 24 passes through the nip portion, the recording paper 24 receives a transport force from the heat roll 52 and also receives a force in the direction opposite to the transport direction (reverse transport force) from the fixing belt 54 side. It becomes.

  By the way, the fixing belt 54 is pressed by the hard pad member 62 at the nip portion, and therefore receives a force in the direction opposite to the rotation direction from the pressure pad 56 as a rubbing resistance. Therefore, as described above, the low friction sheet member 66 is interposed between the fixing belt 54 and the hard pad member 62, and a lubricant is applied to the inner peripheral surface of the fixing belt 54 from the lubricant application member 78. The friction resistance between the fixing belt 54 and the hard pad member 62 is configured to be reduced as much as possible.

  Therefore, in the normal state, the rubbing resistance received by the fixing belt 54 from the hard pad member 62 is extremely small and can be smoothly rotated, so that the fixing belt 54 can rotate at the same speed as the recording paper 24. It is. In this case, the reverse conveying force received by the recording paper 24 is a frictional resistance from the hard pad member 62 via the fixing belt 54, and is at a level that can be ignored. Therefore, the recording paper 24 is stably conveyed at the same speed as the heat roll 52.

  Here, the lubricant application member 78 is disposed so as to be in contact with the inner peripheral surface of the fixing belt 54 and constantly replenishes the inner peripheral surface of the fixing belt 54 with a lubricant such as amino-modified silicone oil. Note that the lubricant is not limited to this, and a commonly used lubricating oil or the like having a required viscosity (for example, a viscosity of 100 cs to a viscosity of 350 cs) can be used as appropriate.

  On the other hand, when the fixing belt 54 circulates and returns to the arrangement position of the lubricant application member 78, it also has a function of collecting the lubricant applied to the inner peripheral surface of the fixing belt 54. In this way, the lubricant application member 78 always applies a certain amount of lubricant to the lubricant application member 78 by simultaneously collecting and supplying the lubricant to the inner peripheral surface of the fixing belt 54. The amount of lubricant retained is also kept constant.

  The fixing belt 54 to which the lubricant is applied by the lubricant applying member 78 is rotated and conveyed to the nip portion. Under the pressing force between the hard pad member 62 and the fixing belt 54 in the nip portion. However, since minute irregularities are formed on the surface of the low friction sheet member 66 on the fixing belt 54 side, most of the lubricant applied to the fixing belt 54 enters the recesses of the low friction sheet member 66. Thus, the sliding portion between the low friction sheet member 66 and the fixing belt 54 is replenished. In this way, the circulating use of the lubricant applied to the inner peripheral surface of the fixing belt 54 can be maintained, and the fixing belt 54 can be smoothly rotated over a long period of time. As a result, it is possible to suppress the occurrence of paper wrinkles and paper jams over a long period until the life of the fixing device 50 is reached.

  As described above, the recording paper 24 on which the toner image is fixed by the fixing device 50 and the image formation is completed is unloaded from the fixing device 50 and provided on the full color printer main body 10 as shown in FIG. It is discharged onto the discharge tray 80 and collected.

  Next, in order to determine the allowable range of the viscosity of the lubricant suitable for the fixing device 50 provided in the full-color printer main body 10 described above, and to determine the allowable range of the surface roughness of the inner peripheral surface of the fixing belt 54. The experiment conducted will be described with reference to FIGS.

  In this experiment, in the fixing device 50 configured as described above, only the lubricant viscosity (oil viscosity) is changed to evaluate the lubricant leakage (oil leakage) and the belt slidability of the fixing belt 54. The results shown in FIG. 6 were obtained.

  In this specification, the term “Initial” means an experiment targeting an unused fixing device 50 (fixing device 50 having an initial performance) after the fixing device 50 is manufactured. "Life" "means a fixing device 50 whose design service life has expired after manufacturing the fixing device 50 (here, the fixing device 50 whose design service life has expired after processing of 100,000 sheets of recording paper has been completed). ).

  As can be seen from the results shown in FIG. 6, in this fixing device 50, when a lubricant having a lubricant viscosity of 50 cs was used, the fluidity was too high and the lubricant leaked. Further, when a lubricant having a lubricant viscosity of 500 cs was used, the belt slidability deteriorated in “life”, and paper wrinkles or paper conveyance delay (paper jam) occurred. Further, when a lubricant having a lubricant viscosity of 1000 cs was used, the belt slidability deteriorated even in “Initial”, and paper wrinkles occurred or paper conveyance delay (paper jam) occurred.

  Therefore, it is determined that the fixing device 50 can use a lubricant having a lubricant viscosity of 50 cs to 1000 cs. Furthermore, when higher performance is required, it is desirable to use a lubricant having a lubricant viscosity of 50 cs to 500 cs.

  Next, looking at an experiment conducted to determine the allowable range of the surface roughness of the inner peripheral surface of the fixing belt 54, the fixing device 50 configured as described above has a lubricant viscosity (oil viscosity) from 50 cs. By setting only between 500 cs and changing only the surface roughness of the inner peripheral surface of the belt, the leakage of the lubricant (oil leakage) was evaluated, and the result shown in FIG. 7 was obtained.

  As can be seen from the results shown in FIG. 7, in the fixing device 50, when the surface roughness Ra (arithmetic mean roughness) of the inner peripheral surface of the belt is set to 0.1 μm and 0.5 μm, “life” and “ In the "Initial", there was no lubricant leakage (oil leakage). However, in the fixing device 50, when the surface roughness Ra (arithmetic average roughness) of the inner peripheral surface of the belt was set to 1 μm, the lubricant leaked (oil leakage) in “life”. Further, in the fixing device 50, when the surface roughness Ra (arithmetic average roughness) of the inner peripheral surface of the belt is set to 5 μm, the leakage of the lubricant (oil leakage) occurs in “life” and “initial”. .

  Therefore, in the fixing device 50, the surface roughness Ra (arithmetic average roughness) of the belt inner peripheral surface is 1 μm or less (here, the lower limit value of the surface roughness Ra of the belt inner peripheral surface is a processing limit of the surface finishing process). It is determined that it can be configured and used.

  Further, when higher performance is required, the surface roughness Ra (arithmetic mean roughness) of the belt inner peripheral surface is 0.5 μm or less (here, the lower limit value of the surface roughness Ra of the belt inner peripheral surface is the surface It is desirable to configure so that it is the processing limit of the finishing process.

  As described above, in this fixing device 50, the lubricant having a lubricant viscosity of 50 cs to 1000 cs is used, and the surface roughness Ra (arithmetic average roughness) of the inner peripheral surface of the belt is 1 μm or less. It is configured to be in a range up to the lower limit value of the surface roughness Ra of the inner peripheral surface of the belt up to (processing limit), and more preferably, the fixing device 50 uses a lubricant having a lubricant viscosity of 50 cs to 500 cs. In addition, the surface roughness Ra (arithmetic mean roughness) of the belt inner peripheral surface is 0.5 μm or less, and the range is up to the lower limit value of the surface roughness Ra of the belt inner peripheral surface up to the processing limit of the surface finishing treatment. With this configuration, the result is that no lubricant leakage (oil leakage) occurs and the belt slidability is deteriorated so that paper is not flawed or paper conveyance delay (paper jam) does not occur. Was confirmed.

  In the fixing device 50, the viscosity of the lubricant is set to 50 cs to 1000 cs, and more preferably 50 cs to 500 cs, so that the lubricant can be applied to the inner peripheral surface of the fixing belt 54 extremely thinly on average, and the fixing belt is used. The coating can be applied uniformly so that there are no uncoated portions on the entire inner peripheral surface of 54.

  In this fixing device 50, the surface roughness Ra (arithmetic average roughness) of the inner peripheral surface of the belt is set to 1 μm or less to the processing limit, and more preferably 0.5 μm or less to the processing limit, so that a very small amount is obtained. The lubricant can be extended thinly on an average over a wide range on the inner circumferential surface of the belt. In addition, when so-called mirror finishing is performed to reduce the surface roughness of the belt inner peripheral surface, the frictional resistance between the inner peripheral surface of the fixing belt 54 and the low friction sheet member 66 can be reduced, and therefore less. With the amount of lubricant, the inner peripheral surface of the fixing belt 54 can smoothly slide on the low friction sheet member 66.

  Therefore, in this fixing device 50, by setting the viscosity of the lubricant to 50 cs to 1000 cs, and more desirably 50 cs to 500 cs, the lubricant can be applied to the inner peripheral surface of the fixing belt 54 extremely thinly and evenly on average. In addition, by setting the surface roughness Ra (arithmetic mean roughness) of the inner peripheral surface of the belt from 1 μm or less to the processing limit, more preferably from 0.5 μm or less to the processing limit, a very small amount of lubricant can be obtained. Synchronously acting on the inner surface of the belt so that it can be stretched thinly on the average, and the inner surface of the belt becomes a smooth state (smooth state) like a mirror surface. In combination with the low frictional resistance with the low friction sheet member 66, the inner peripheral surface of the fixing belt 54 and the low friction are reduced by a minimum amount of lubricant. It is possible to maintain an appropriate lubrication between the rubbing sheet member 66 and maintain good belt slidability so as not to cause wrinkles on the paper or paper conveyance delay (paper jam).

  In addition, an average amount of lubricant that is applied to the inner peripheral surface of the fixing belt 54 on average is squeezed out to the nip portion that is pressed between the pressure pad 56 and the heat roll 52 as it is. Therefore, the lubricant can be prevented from being accumulated in a portion of the nip portion in the transport direction and the leakage of the lubricant flowing out from both ends of the fixing belt 54.

  In other words, if the lubricant is applied to the inner peripheral surface of the fixing belt 54 without being excessively thin and even, it is possible to prevent the lubricant from being squeezed out before the nip portion and causing lubricant leakage. In addition, by setting the viscosity of the lubricant appropriately, it is possible to prevent the lubricant from flowing out because the viscosity of the lubricant is too low, and furthermore, a very small amount of lubricant because the viscosity of the lubricant is too high. However, it is possible to prevent the inner peripheral surface of the fixing belt 54 from being applied extremely thinly and uniformly, and the lubricant can be applied to the inner peripheral surface of the fixing belt 54 in the best condition.

  In particular, when an amino-modified silicone oil with excellent affinity is used as a lubricant, this amino-modified silicone oil forms a film with a thickness of about 2 molecules and can exhibit good lubricating performance. By setting the viscosity of the agent to the above-described appropriate value and setting the surface roughness of the inner peripheral surface of the fixing belt 54 to the above-described appropriate value, the effect exerted can be synergistically expanded, and a dramatic effect can be expected. .

  In the fixing device according to the present invention, lubricant leakage (oil leakage) is prevented by appropriately setting the viscosity of the lubricant and appropriately setting the surface roughness of the inner peripheral surface of the fixing belt 54. In addition, the means for maintaining good belt slidability is not only used in the fixing device shown in FIGS. 1 to 7, but also a heating belt is used as a heating means. The present invention can also be applied to a fixing device used in an electrophotographic image forming apparatus configured using a pressure roll as a pressure unit.

  In this case, for example, the fixing belt is disposed on the toner image carrying surface side of the recording paper, and a ceramic heater which is a pressure member having a heat generation source is disposed inside the fixing belt, and the ceramic heater is disposed at the nip portion. The fixing device is configured to supply heat. The ceramic heater is disposed over the entire width of the fixing region to form a nip portion. Further, a low friction sheet member is disposed between the inner peripheral surface of the fixing belt and the ceramic heater in order to reduce the frictional resistance.

  Further, in this case, a lubricant application member is provided which is in sliding contact with the inner peripheral surface of the fixing belt and simultaneously supplies and recovers the lubricant, and the lubricant set to a required viscosity is supplied from the lubricant application member. refill. Further, the inner peripheral surface of the fixing belt with which the lubricant application member is slidably contacted is mirror-finished to finish the surface with a required surface roughness. By configuring in this way, the same operations and effects as those shown in FIGS. 1 to 7 described above can be achieved.

  Further, in the fixing device according to the present invention, by appropriately setting the viscosity of the lubricant and appropriately setting the surface roughness of the inner peripheral surface of the fixing belt 54, leakage of the lubricant (oil leakage) can be prevented. Of course, the means for maintaining good belt slidability can be used for fixing devices having various configurations. Furthermore, it goes without saying that the present invention can have other various configurations without departing from the gist of the present invention.

DESCRIPTION OF SYMBOLS 10 Full color printer main body 50 Fixing device 52 Heat roll 54 Fixing belt 56 Pressure pad 60 Soft pad member 62 Hard pad member 66 Low friction sheet member 70 Holder member 78 Lubricant application member

Claims (2)

A fixing device for fixing a toner image carried on a recording medium,
A rotating member that is elastically deformed and rotationally driven;
A fixing belt formed in an endless belt shape that comes into contact with the rotating member;
A soft pad member that is inside the fixing belt and applies a predetermined pressure to the rotating member by pressing the rotating member via the fixing belt;
A pad member main body that has a locking piece projecting in a projecting shape at a plurality of positions on a straight line along the longitudinal direction, and that is inside the fixing belt and supports the soft pad member;
The plurality of locking pieces have a plurality of engaging holes to be inserted and engaged with each other, and are wound around the pad member body so as to cover the soft pad member, so that they face the fixing belt. A low friction sheet member arranged so as to be bent;
A lubricant application member for replenishing the lubricant by sliding contact with the inner peripheral surface of the fixing belt;
An escape groove for loosely inserting the locking piece is formed, supporting the pad member main body via an elastic sheet member, and a holder member supporting the lubricant application member on the opposite side of the pad member main body,
With
The fixing device for an electrophotographic system, wherein the low friction sheet member is composed of a woven fabric of weft and warp.   An image forming apparatus comprising the fixing device according to claim 1.

Images