JP2007171694A - Endless belt used for fixing device, fixing device using the endless belt and image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a fixing device provided with stable fixing performance without increasing a warm-up time and to provide an image forming apparatus. <P>SOLUTION: The fixing device 7 has a press roll 73 making rotary driving, a fixing belt 71 making driven rotation by abutting on the press roll 73, a pressure support 72 pressing the fixing belt 71 from the inside, and a halogen lamp 74 disposed within the circumference of the fixing belt 71, and heats the fixing belt 71 by the radiation heat from the halogen lamp 74 and the heat conduction via the pressure support 72, the fixing device 7 in which the fixing belt 71 has a first layer consisting of a metallic metal base material extending like a tube and further has a second layer of ≥0.9 in thermal emissivity on a surface sliding and rubbing with the pressure support 72. The fixing belt 71 is also suitably provided further with an elastic layer if needed. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an endless belt used in a fixing device for fixing an unfixed image carried on a surface of a recording medium to the recording medium by heating and pressurizing the recording medium, a fixing device thereof, and an image forming apparatus It is about.

  As an image forming technique, an electrophotographic system is widely used. The electrophotographic apparatus has a high printing speed, is simple because it is not necessary to prepare a printing plate each time, can directly obtain images from various image information, the apparatus is relatively small, and full color can be easily obtained. There are many advantages such as being.

  In such an electrophotographic apparatus, in the normal fixing step, a two-roll type fixing device in which a heating roll and a pressure roll are in contact with each other is used, and an unfixed toner image is formed in a nip portion formed by the contact between both. By inserting the recording medium formed on the surface, the toner is melted by heat and pressure and fixed as a permanent image on the surface of the recording medium. Instead of this heating roll and / or pressure roll, an endless belt-shaped heating member or pressure member may be used.

  The heating roll is formed by providing an elastic layer and a release layer on a metal core having a heat source such as a halogen lamp inside, and the surface of the heating roll is heated from the inside by the heat source. In the fixing device, a heating member such as a heating roll can be instantaneously heated from the viewpoint of energy saving and preventing the user from waiting when using the image forming apparatus. ) As much as possible.

  A conventional fixing device has a fixing roll (heating roll) as a hollow fixing body, a pressure roll pressed against the fixing roll by a biasing means, and a halogen heater (fixing heater) as a heating means. The fixing roll is heated by supplying electric power from a power source to the halogen heater. Further, the output of a sensor for detecting the surface temperature of the fixing roll is input to a temperature control, and the halogen heater is turned on / off based on the output by the temperature control, so that the fixing roll is maintained at a predetermined surface temperature. . An unfixed image made of unfixed toner on the recording medium is permanently fixed by being heated and pressed together with the recording medium in a fixing nip formed by the fixing roll and the pressure roll.

  Conventional fixing rollers with a hollow cylindrical shape are difficult to process the shape of the fixing nip into a free shape, causing wrinkles and curls on the recording medium, affecting transportability, and fixing. It has been difficult to satisfy all of the various types of recording media, such as creating restrictions for improving the performance and the like.

  For example, in a recording medium having a multilayer structure of two or more layers, such as an envelope, if the shape of the nip portion between the fixing roll and the pressure roll has a curvature instead of a flat surface, both rotations Even if the speed is the same, there may be a slight difference in the linear velocity on the surface, causing a deviation in the conveyance speed on the top and bottom surfaces of the recording medium, causing wrinkles, and affecting the fixability and conveyance performance. Such a problem may occur. In particular, when the process speed is to be increased, the above-mentioned problems are likely to occur.

  In order to solve the above problems, a technique disclosed in Patent Document 1 is disclosed. This has a hollow pipe provided with a heat source therein, a pressure roll that pressurizes the hollow pipe, and a heat-resistant endless sheet wound around the hollow pipe, and the endless sheet and the pressure roll A fixing device that performs heating and pressure fixing by passing a recording paper (recording medium) carrying unfixed toner in between, and the surface of the recording paper carrying the unfixed toner is in contact with the endless sheet The endless sheet is a fixing device that rotates at the same speed as the conveyance speed of the recording paper, and the pressing position of the hollow pipe by the pressure roll is a substantially planar shape.

JP-A-7-287460

  However, in such a fixing device, since the entire hollow pipe is heated by the halogen heater, the portion other than the nip portion of the hollow pipe that does not contribute to fixing is heated, and the entire fixing member is predetermined. It takes time to raise the temperature to the temperature, and there is a problem that the warm-up is not shortened.

  Further, when continuous paper is passed, heat is taken away by the recording paper at the nip portion of the hollow pipe, so that a temperature drop occurs. In order to maintain the nip portion temperature of the hollow pipe at a predetermined temperature, it is necessary to heat from a heat source, but the portion of the hollow pipe opposite to the nip portion as viewed from the heat source is heated. It would rapidly become a high temperature since there is no be deprived. As a result, it is necessary to reduce the printing speed or stop the printing so that the temperature of the portion is equal to or lower than the predetermined temperature.

  In order to solve the above problem, for example, a fixing device as shown in FIG. 8 is conceivable. The fixing device 90 shown in FIG. 8 is driven to rotate while forming a pressure roll 91 having elasticity or flexibility and a nip portion N through which the recording medium P is inserted in contact with the pressure roll 91 having elasticity or flexibility. A heat-resistant endless belt 92 that has a flat surface portion, presses the heat-resistant endless belt 92 from the inside with the flat surface portion, and forms a nip portion N in a substantially flat shape; And a heat source 82 disposed in the circumference. Further, the pressing support body 68 extends so as to surround the heat source 82 from the flat portion toward the front and back in the traveling direction of the heat-resistant endless belt 92. The pressing support 68 is formed by opening at least a part of the opposite side of the flat surface with the heat source 82 as a base point, and directly heats the heat-resistant endless belt 92 by radiant heat from the heat source 82. Heating is performed by heat conduction through the pressing support 68.

  However, with this method, when aiming at high speed and high image quality and color with an elastic layer, the base material of the heat-resistant endless belt (the base material here is substantially the rigidity of the endless belt, When a heat resistant resin is used as a material (which is a layer having strength), an increase in preheating time and a problem of fixing failure are likely to occur due to the poor thermal conductivity. Therefore, as countermeasures, there are methods of increasing the amount of thermally conductive particles such as carbon black and thinning the base material layer, but all of them cause a decrease in the strength of the belt, and the belt breaks or buckles. It is difficult to achieve both of these improvements.

  Therefore, it is conceivable to use, for example, a thin film metal having a high thermal conductivity of about 15 to 80 μm as the base material of the endless belt. For example, the material of the thin film metal includes stainless steel, nickel alloy, aluminum alloy and the like.

  However, in such a fixing device, the frictional surface of the pressing support 68 that rubs against the inner surface of the heat-resistant endless belt 92 and the endless belt 92 is a flat surface, and therefore has a large contact area. Therefore, the sliding torque between the inner surface of the endless belt 92 when rotating the endless belt 92 and the surface of the pressing support 68 becomes large, and when continuous paper is passed, a large amount from the sliding surface. Wear powder may be generated. This further increases the sliding resistance between the inner surface of the endless belt 92 and the surface of the pressing support 68 and increases the driving torque, leading to a belt slip phenomenon, and may damage the inner surface of the endless belt 92. is there. In addition, there is a problem that the durability of the endless belt 92 and the pressing support 68 is reduced due to wear, and a problem that the fixing property and the transportability are affected is likely to occur.

  Moreover, when the above-mentioned metal thin film was used as an endless belt, these metal materials were used for the base material with an emissivity of 0.05 to 0.1. Since it is very low compared to the heat-resistant resin material, it is difficult to absorb the radiant heat from the heat source, which is a feature of this method, and as a result, there is a possibility that the heating of the belt by the radiant heat is delayed.

  The present invention has been made to solve the technical problems as described above. The object of the present invention is particularly suitable for a fixing device having stable fixing performance without increasing the warm-up time. The object is to provide an endless belt that is used and highly durable.

  Another object of the present invention is to provide a fixing device and an image forming apparatus that have an endless belt having high durability and have stable fixing performance without increasing warm-up time.

  The configuration of the present invention is as follows.

  (1) An endless belt having a first layer made of a metal base material extending in a tubular shape, wherein a second layer having a thermal emissivity of 0.9 or more is included in the first layer. An endless belt, further comprising a circumferential surface side.

  (2) A pressure roll that is rotationally driven, an endless belt that is driven to rotate in contact with the pressure roll, a pressure support that presses the endless belt from the inside, and a heat source disposed within the circumference of the endless belt And an endless belt used in a fixing device that heats the endless belt by radiant heat from the heat source and heat conduction through the pressing support, wherein the endless belt extends in a tubular shape. An endless belt, further comprising a second layer having a first layer made of a base material and having a thermal emissivity of 0.9 or more on a surface that rubs against the pressing support.

  (3) A pressure roll that is rotationally driven, an endless belt that rotates in contact with the pressure roll, a pressure support that presses the endless belt from the inside, and a heat source that is disposed within the circumference of the endless belt The endless belt has a first layer made of a metal base material that extends in a tubular shape, and has a thermal emissivity on a surface that rubs against the pressing support. A fixing device that further includes a second layer having a thickness of 0.9 or more, and that heats the endless belt by radiant heat from the heat source and heat conduction through the pressing support.

  (4) Charging means for charging the surface of the image carrier, electrostatic latent image forming means for forming an electrostatic latent image corresponding to image information on the charged surface of the image carrier, and formation on the surface of the image carrier A developing means for developing the electrostatic latent image formed with toner to obtain a toner image; a transfer means for transferring the toner image formed on the surface of the image carrier to the surface of the recording medium; and a transfer means for transferring to the surface of the recording medium An image forming apparatus including at least a fixing unit configured to fix the toner image, wherein the fixing unit includes: a pressure roll that is rotationally driven; an endless belt that is driven to rotate in contact with the pressure roll; A pressing support that presses the endless belt from the inside; and a heat source disposed in a periphery of the endless belt, wherein the endless belt is formed of a metal base material that extends in a tubular shape. Having a layer and before A second layer having a thermal emissivity of 0.9 or more is further provided on a surface that rubs against the pressing support, and the endless belt includes radiant heat from the heat source, and heat conduction through the pressing support. An image forming apparatus that is heated by the above.

  According to the present invention, an increase in sliding torque between the inner surface of the endless belt and the surface of the support, which can occur when the endless belt is rotated, generation of a large amount of wear powder from the sliding surface, belt slip phenomenon, Damage to the inner surface of the endless belt can be prevented or suppressed. In addition, it is possible to reduce the occurrence of a problem that the durability of the endless belt and the pressure support body is reduced due to wear, and the problem of affecting the fixing property and the transportability.

  Furthermore, since the metal thin film material has a low emissivity, it is possible to improve the problem that the radiant heat from the heat source is hardly absorbed and the heating speed of the belt becomes slow.

  Hereinafter, specific embodiments of the present invention will be described in detail with reference to preferred embodiments.

  FIG. 1 is a schematic cross-sectional view showing a fixing device according to a first embodiment which is an example of a fixing device of the present invention, and FIG. 2 is a schematic configuration diagram of an image forming apparatus including the fixing device. FIG. 7 is a schematic configuration diagram of a color image forming apparatus including such a fixing device.

  As shown in FIG. 2, the image forming apparatus is roughly divided into two configurations of an image forming unit (image forming unit) X and a fixing unit (fixing unit) Y.

  The image forming unit X shown in FIG. 2 will be described below.

  In FIG. 2, the image forming unit X forms a latent image due to a difference in electrostatic potential on the surface by irradiating image-like light after uniform charging, and rotates a photosensitive drum (latent image) in the direction of arrow D. A charging roll (charging means) 2 for uniformly charging the surface of the photosensitive drum 1 in order in the rotation direction, that is, in the direction of the arrow D, and the photosensitive drum 1 An image exposure device (electrostatic latent image forming means) 3 that irradiates image-like light to form an electrostatic latent image on the surface, and selectively transfers toner to the latent image formed on the surface of the photosensitive drum 1. The transfer bias electric field between the developing device (developing means) 4 for forming a toner image (unfixed image) and the photosensitive drum 1 is opposed to the photosensitive drum 1 with the recording paper (recording medium) P interposed therebetween. And a transfer roll (transfer means) 5 that generates toner and remains on the photosensitive drum 1 after the toner image is transferred. Cleaner (cleaning member) 6 and is provided configured to remove toner.

  As the photosensitive drum 1, a metal drum having a photosensitive layer made of an organic photosensitive material, an amorphous selenium photosensitive material, an amorphous silicon photosensitive material, or the like can be used.

  The charging roll 2 is a roll made of a metal such as stainless steel or aluminum and coated with a high-resistance material. The charging roll 2 is in contact with the photosensitive drum 1 and is driven to rotate. When a predetermined voltage is applied, a continuous discharge is generated in a minute gap near the contact portion between the charging roll 2 and the photosensitive drum 1, and the surface of the photosensitive drum 1 is charged almost uniformly. Is.

  The image exposure unit 3 generates a flashing laser beam based on an image signal, and scans this in the main scanning direction of the photosensitive drum 1 by a polygon mirror. It forms a latent image.

  The developing device 4 contains toner, and a developing roll carrying the toner is brought close to and opposed to the photosensitive drum 1 to transfer the toner corresponding to the electrostatic latent image formed on the surface of the photosensitive drum 1. Thus, a visualized toner image (unfixed image) is formed (developed).

  The transfer roll 5 is made of a conductive or semiconductive roll-shaped member, and a transfer bias voltage is applied between the transfer roll 5 and the surface of the photosensitive drum 1 to transfer the toner image on the surface of the photosensitive drum 1 to paper or an OHP sheet. Are transferred onto the recording medium P.

  The cleaner 6 is a blade-like member pressed against the surface of the photosensitive drum 1 and removes the toner remaining on the surface of the photosensitive drum 1 so as to scrape off. The cleaning member is not limited to this, and instead of such a blade-like member, for example, a member that scrapes off toner with a roll member or a member that sweeps out toner with a brush may be used.

  Further, a sheet feeding mechanism (not shown) is configured so that the recording medium P is supplied to the facing portion between the photosensitive drum 1 and the transfer roll 5 from the upstream side (right side in FIG. 2) in the direction of arrow C. ing. The toner image is transferred from the photosensitive drum 1 by the transfer roll 5 to the surface of the recording medium P conveyed to the facing portion. That is, in the image forming unit X, a toner image (unfixed image) is formed on the surface of the recording medium (transfer medium) P.

  On the other hand, the fixing unit Y located on the downstream side of the image forming unit X in the conveyance direction (arrow C direction) of the recording medium P heats and melts the toner image transferred to the surface of the recording medium P to form the recording medium P. The fixing device 7 is used for pressure bonding. The fixing device 7 is the fixing device of the first embodiment shown in FIG.

  Next, the color image forming apparatus in FIG. 7 will be described.

  A color image forming apparatus (also referred to as an electrophotographic apparatus) 220 shown in FIG. 7 is an intermediate transfer type color image forming apparatus, and four electrophotographic photosensitive members 401 a to 401 d (for example, an electrophotographic photosensitive member 401 a are included in a housing 420. Yellow, electrophotographic photosensitive member 401b can be formed in magenta, electrophotographic photosensitive member 401c can be formed in cyan, and electrophotographic photosensitive member 401d can be formed in black.) Are arranged in parallel with each other along intermediate transfer belt 409. Has been.

  Here, the electrophotographic photoreceptors 401a to 401d mounted on the electrophotographic apparatus 220 are respectively the electrophotographic photoreceptors (for example, the photoreceptor drum 1) of the present invention.

  Each of the electrophotographic photosensitive members 401a to 401d can be rotated in a predetermined direction (counterclockwise on the paper surface), and the charging rolls 402a to 402d, the developing devices 404a to 404d, and the primary transfer roll 410a along the rotation direction. To 410d and cleaning blades 415a to 415d are arranged. Each of the developing devices 404a to 404d can be supplied with toners of four colors, black, yellow, magenta, and cyan accommodated in toner cartridges 405a to 405d, and the primary transfer rolls 410a to 410d are respectively intermediate transfer belts. 409 is in contact with the electrophotographic photoreceptors 401a to 401d.

  Further, a laser light source (exposure device) 403 is disposed at a predetermined position in the housing 420, and the surfaces of the charged electrophotographic photoreceptors 401a to 401d are irradiated with laser light emitted from the laser light source 403. Is possible. Accordingly, charging, exposure, development, primary transfer, and cleaning are sequentially performed in the rotation process of the electrophotographic photosensitive members 401a to 401d, and the toner images of the respective colors are transferred onto the intermediate transfer belt 409 in an overlapping manner.

  The intermediate transfer belt 409 is supported with a predetermined tension by a drive roll 406, a backup roll 408, and a tension roll 407, and can rotate without causing deflection due to the rotation of these rolls. Further, the secondary transfer roll 413 is disposed so as to contact the backup roll 408 via the intermediate transfer belt 409. The intermediate transfer belt 409 passing between the backup roll 408 and the secondary transfer roll 413 is cleaned by, for example, a cleaning blade 416 disposed in the vicinity of the drive roll 406 and then repeatedly used for the next image forming process. Is done.

  A tray (transfer medium tray) 411 is provided at a predetermined position in the housing 420, and the transfer medium 500 such as paper in the tray 411 is transferred to the intermediate transfer belt 409 and the secondary transfer roll by the transfer roll 412. After being sequentially transferred to the fixing device 414, the paper is discharged outside the housing 420. The fixing device 414 corresponds to the fixing device of the first embodiment shown in FIG.

  Next, the fixing unit Y will be described with reference to FIG.

  A fixing device 7 according to an embodiment of the present invention shown in FIG. 1 includes a halogen lamp (heat source) 74 having an output of about 500 W to 1000 W, a flat support H, and a pressing support 72 arranged so as to surround it. A heat-resistant fixing belt (endless belt) 71 hung so as to surround the outer periphery of the pressing support 72; a pressure roll 73 that pressurizes the fixing support 71 at the position of the flat surface portion H of the pressing support 72; Have A nip portion N is formed between the fixing belt 71 and the pressure roll 73, and the recording medium P carrying an unfixed toner image is inserted in this direction in the direction of the arrow C so that heat and pressure fixing is performed. Is called.

  The halogen lamp 74 is arranged at a position shifted from the axial center position of the fixing belt 71 by a predetermined distance in a direction close to the nip portion N, and is configured to mainly heat the nip portion N. With the halogen lamp 74 (more specifically, the filament in the halogen lamp 74) as a base point, the pressing support 72 is disposed in a state of surrounding the press support 72 so as to have a predetermined central angle.

  As shown in FIG. 3, the halogen lamp 74 as a heat source is, for example, made of glass and has a cylindrical shape, and a filament 79 is arranged on a substantially axial center of the lamp tube 70. Further, a partial region G on the peripheral surface of the lamp tube 70 includes a coating portion 75 covered with, for example, white ceramics. As the range of the region G, in the embodiment of the present invention, it is preferable that the filament 79 has a central angle of 180 ° to 270 ° with the base point (center) as a base point. By providing a heat semi-shielding member such as white ceramic in this range, the flat surface portion H of the pressing support 72 corresponding to the nip portion N can be positively heated, and the fixing belt 71 and the pressing support 72 can be heated. It is possible to prevent the portions other than the flat portion H from being excessively heated.

  The pressing support 72 can be made of a highly rigid material having good durability and heat resistance, such as iron or aluminum, but an aluminum-based material is preferable from the viewpoint of thermal conductivity.

  The pressing support 72 is in a state where the opposite side to the flat surface portion H is open. Further, the flat surface portion H of the pressing support 72 is substantially flat, and sufficient pressure is applied to the fixing belt 71 by the pressure roll 73, and when the pressure roll 73 rotates, the fixing belt 71. And the recording medium P are conveyed together. At this time, since the nip portion N is also formed in a substantially flat shape, the conveyance speed (linear velocity) of both is substantially the same, and wrinkles and curling can be prevented. In addition, the contact area with the belt is large, and the sliding resistance becomes larger than in the case of a nip portion by a normal roll pair. As a result, the driving torque increases, and the belt does not rotate smoothly and slip phenomenon is likely to occur.

  Therefore, the pressing support 72 is also preferably subjected to a roughening process on the flat surface portion H by a known blasting process or the like. In addition, as roughness of this plane part H, 0.1 micrometer-3 micrometers are preferable by Ra, More preferably, 0.5 micrometer-1.5 micrometers are preferable. If the thickness is 0.1 μm or less, the intended reduction in sliding resistance is insufficient. If the thickness is 3 μm or more, the inner surface of the belt is damaged, or fixing unevenness due to roughness occurs on the fixed image. The roughening process is not limited to the blasting process, and may be a known surface roughening process such as laser processing, polishing, cutting, or rolling.

  Here, the surface roughness Ra is an arithmetic average roughness which is one of the measures of roughness, and a known stylus type surface roughness measuring machine (for example, Surfcom 1400A: manufactured by Tokyo Seimitsu Co., Ltd.) is used. Can be measured using.

  The measurement of the surface roughness Ra in the pressing support 72 of the present embodiment is based on JIS B0601-1994, using Surfcom 1400A, evaluation length Ln = 4 mm, reference length L = 0.8 mm, cut-off The measurement was performed under the measurement condition of value = 0.8 mm. Although it is possible to measure under other conditions, it is preferable to measure under conditions that can be correlated with the above-mentioned measurement conditions, and the measured values are converted to values evaluated under the above-described measurement conditions. It is evaluated by.

  On the other hand, the pressure roll 73 uses a so-called soft roll formed by forming an elastic layer made of a highly elastic heat-resistant material such as silicone rubber or a foam thereof on a metal core. Since the surface layer of the pressure roll 73 is a soft roll, the pressure roll 73 is appropriately dented in the nip portion N, and the shape of the nip portion N is affected by the flat portion H of the pressing support 72 and is substantially flat. It becomes.

  Note that the surface property of the pressure roll 73 is that the surface of the pressure roll 73 is elastic or flexible enough to be substantially planar by contact with the flat surface portion H of the pressing support 72, depending on the purpose. Various materials can be appropriately selected.

  FIG. 4 shows an enlarged cross-sectional view of the fixing belt 71. As shown in FIG. 4, the fixing belt 71 includes a release layer 71A, a metal thin film layer (also referred to as a metallic base material layer) 71B, and a sliding layer 71C.

  The release layer 71A is made of a material (for example, silicone resin, fluororesin, etc.) having a thickness of 5 μm to 100 μm, preferably about 1 μm to 40 μm and having good release properties and durability. From the viewpoint of releasability from toner and wear resistance, fluororesin is suitable. As the fluororesin, tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer (PFA), polytetrafluoroethylene (PTFE), tetrafluoroethylene-hexafluoropropylene copolymer (FEP) and the like can be used. The release layer 71A functions to prevent the toner from adhering to the fixing belt 71 when the toner image transferred onto the surface of the recording medium P is heated and melted and pressed onto the recording medium P. Although it is usually used for the outermost peripheral surface of 71, it may not be necessary depending on the properties of the toner.

  Further, as the material of the metal thin film layer 71B, a material having a good thermal conductivity such as aluminum, aluminum alloy, stainless steel (SUS), nickel alloy having a thickness of 15 μm to 100 μm, preferably about 30 μm to 70 μm is used. In particular, aluminum alloys such as 3000 series and 5000 series, SUS base materials such as SUS304 and SUS316, and nickel alloys such as Hastelloy are easy to process and can secure a desired rigidity.

  The material used for the sliding layer 71C is not particularly limited as long as it does not melt at a fixing control temperature and has a thermal emissivity of 0.9 or more. For example, polyimide resin, fluororesin, silicon resin, Heat-resistant resins such as polybenzimidazole resins and polyether ether ketones are preferable, and in order to further improve the wear resistance and heat absorption of the layers made of these heat-resistant resins, those further containing a filler are also preferable. . The thickness of the sliding layer 71C is preferably 5 μm or more and 50 μm or less. If the thickness of the sliding layer 71C is less than 5 μm, it may be worn away for a long time or the inner surface roughness of the metal thin film layer 71B cannot be covered and the metal thin film layer 71B is partially exposed. There is a risk of malfunction. On the other hand, if the thickness of the sliding layer 71C exceeds 50 μm, the high thermal conductivity of the metal thin film cannot be sufficiently exhibited, and the cost is increased.

  When the filler used for the sliding layer 71C has a large particle size, if the filler falls off due to sliding with the pressing support 72, the dropped filler is caught by the pressurizing portion of the pressing support 72. As a result, pressure is locally applied to the metal thin film layer 71B, which may lead to damage to the metal thin film layer 71B. For this reason, the particle size of the filler that can be used for the sliding layer 71C is preferably 10 μm or less, and more preferably 2 μm or less. Even if the particle size of the filler is 10 μm or less, if the particle size exceeds half the thickness of the sliding layer 71C, it may be difficult to form the sliding layer uniformly. Examples of filler materials include oxides such as silica, alumina, iron oxide, and titanium oxide, carbonate fillers such as barium sulfate, nitride fillers such as boron nitride, and carbon such as carbon black and graphite. A system filler or the like is used.

  In addition to the heat-resistant resin material, the material used for the sliding layer 71C is an abrasion-resistant material that can withstand sliding and has high heat radiation, specifically, a formed sliding There is no particular limitation as long as the thermal emissivity of the layer 71C is 0.9 or more. For example, in the case of an aluminum thin film base material, alumite having a high thermal emissivity is formed, and in the case of other materials, the layer is formed by plating or the like. It doesn't matter.

  With such a configuration, regarding the heating of the fixing belt 71, the sliding layer 71 </ b> C can be directly heated by the radiant heat from the halogen lamp 74 on the side opposite to the nip portion N where the pressing support 72 is opened. At the same time, it can be indirectly heated by heat conduction through the pressing support 72. That is, the fixing belt 71 can be heated by heat conduction from the pressing support 72 in the nip portion where heat is removed, and the fixing belt 71 deprived of heat there is a halogen lamp in a place away from the nip portion N. The heat can be heated by radiant heat from 74, and heat can be efficiently applied to the fixing belt 71 as a whole.

  As described above, in the present embodiment, the metal thin film layer 71B made of a metal base material that extends in a tubular shape has a thermal emissivity of 0.9 on the surface that slides on the pressing support 72. By using the endless belt further including the sliding layer 71C as described above as the fixing belt 71, the temperature at the nip portion N of the fixing belt 71 and the pressing support 72 can be easily and appropriately controlled to a predetermined temperature. it can. Further, since the fixing belt 71 is efficiently heated, the warm-up can be shortened.

  The thermal emissivity here is a numerical value representing the intensity of infrared rays emitted when an object is heated, expressed as a ratio when the ideal black body is 1.0 (100%). It can be measured using a known thermal emissometer (for example, D & S AERD: manufactured by Kyoto Electronics Industry Co., Ltd.).

  The thermal emissivity in the sliding layer 71C of the present embodiment is set using a emissometer D & S AERD in a geodetic wavelength region of 3 to 30 μm and placed in a 25 ° C. warm-up period for 10 minutes, and then the detector section is placed. The measurement was performed for about 15 seconds on the object. Although it is possible to measure under other conditions, it is preferable to measure under conditions that can be correlated with the above-mentioned measurement conditions, and the measured values are converted to values evaluated under the above-described measurement conditions. It is evaluated by.

  As another embodiment of the present invention, it is preferable to use the fixing belt 81 shown in FIG. 5 instead of the fixing belt 71.

  As shown in FIG. 5, the fixing belt 81 includes a release layer 81A, a metal thin film layer 81B, and a sliding layer 81C, and further includes an elastic layer 81D between the release layer 81A and the metal thin film layer 81B. is doing. That is, the entire fixing belt 81 has a configuration in which an elastic layer is further provided on the fixing belt 71 shown in FIG.

  The release layer 81A is made of a material (for example, a silicone resin or a fluororesin) having a thickness of 1 μm to 50 μm, preferably about 10 μm to 40 μm and having good release properties and durability. The release layer 81A may be the same as the release layer 71A described above, and is usually used on the outermost peripheral surface of the fixing belt 81. The properties of the elastic layer 81D described later are This is not always necessary depending on the properties of the toner to be fixed.

  Further, as the material of the metal thin film layer 81B, the same material as that of the metal thin film layer 71B described above may be used, and aluminum, aluminum alloy, stainless steel (SUS), nickel alloy having a thickness of about 30 μm to 60 μm, etc. A material with good thermal conductivity is used.

  As the material used for the sliding layer 81C, the same material as the sliding layer 71C described above may be used, as long as it does not melt at the fixing control temperature and has a thermal emissivity of 0.9 or more. There is no particular restriction. The thickness of the sliding layer 81C is preferably 5 μm or more and 50 μm or less. If the thickness of the sliding layer 81C is less than 5 μm, it may be worn away for a long time or the inner surface roughness of the metal thin film layer 81B cannot be covered and the metal thin film layer 81B is partially exposed. There is a risk of malfunction. On the other hand, if the thickness of the sliding layer 81C exceeds 50 μm, the high thermal conductivity possessed by the metal thin film cannot be sufficiently exhibited, and the cost increases.

  In addition to the heat-resistant resin material, the material used for the sliding layer 81C is a wear-resistant material that can withstand sliding and has high thermal radiation, specifically, a formed sliding If the thermal emissivity of the layer 81C is 0.9 or more, it is not particularly limited. It doesn't matter. Furthermore, the same fillers that can be used for the sliding layer 71C of the fixing belt 71 shown in FIG. 4 may be used in combination.

  As a material used for the elastic layer 81D, an elastic material having heat resistance such as silicone rubber or fluororubber is preferably used. The thickness of the elastic layer 81D may be appropriately adjusted according to desired requirements, but is preferably 50 μm to 1000 μm.

  Further, when the adhesion between the metal thin film layer 81B and the elastic layer 81D is insufficient, there is a method in which a primer layer is applied and formed in advance on the surface of the metal thin film layer 81B as necessary. Examples of the material for the primer layer include, but are not limited to, polyphenylene sulfide, polyethersulfone, polysulfone, polyamideimide, polyimide, and derivatives thereof. Moreover, as thickness of a primer layer, the range of 0.5-5 micrometers is preferable.

  When forming a primer layer and an elastic layer 81D (not shown), after preparing an endless belt including a metal thin film layer 81B extending in a tubular shape, the primer layer and the elastic layer 81D are formed on the outer peripheral surface of the endless belt. It is also possible to take a method of coating or coating an appropriate resin tube as a known elastic layer material. The primer layer may also be used between any of the fixing belts 71 and 81 shown in FIGS. 4 and 5 as necessary.

  With such a configuration, regarding the heating of the fixing belt 81, the sliding layer 81 </ b> C can be directly heated by the radiant heat from the halogen lamp 74 on the side opposite to the nip portion N where the pressing support 72 is opened. At the same time, it can be indirectly heated by heat conduction through the pressing support 72. That is, the fixing belt 81 can be heated by heat conduction from the pressing support 72 at the nip portion where heat is taken away, and the fixing belt 81 where heat is taken away there is a halogen lamp at a place away from the nip portion N. The heat can be heated by the radiant heat from 74 and heat can be efficiently applied to the fixing belt 81 as a whole.

  As described above, in the present embodiment, instead of the fixing belt 71, the metal thin film layer 81 </ b> B made of a metal base material that extends in a tubular shape is provided on the surface that rubs against the pressing support 72. By using an endless belt having a sliding layer 81C having a thermal emissivity of 0.9 or more and further having an elastic layer 81D as the fixing belt 81, in addition to the effect of using the fixing belt 71, toner The followability to the unevenness and the unevenness of the recording medium P becomes good. For this reason, not only the black and white fixing device but also a finer reproducibility is required. For example, even when used as a color fixing device, a remarkable effect can be exhibited.

  Furthermore, as another embodiment of the present invention, a fixing device 7 shown in FIG. 6 can also be suitably used instead of the fixing device shown in FIG. In FIG. 6, the rest is substantially the same as the fixing device shown in FIG. 1 except that a lubricant supply member 80 is provided. The member 80 is made of a heat-resistant fiber impregnated with a heat-resistant lubricant such as silicone oil, for example, the sliding layer 71C (or 81C) of the fixing belt 71 (or 81), and a pressure support. Lubricant is supplied to the surface that rubs against 72. By supplying a predetermined amount of lubricant to the rubbing surface, it becomes possible to prevent wear of the sliding layer of the pressing support 72 and the fixing belt and an increase in sliding torque. Therefore, the image forming apparatus can be preferably used.

[Example 1]
In the image forming apparatus illustrated in FIG. 2, the fixing device 7 illustrated in FIG. 1 is used as the fixing unit Y.

  A PFA having a thickness of 30 μm was used as the material of the release layer 71A, and a SUS base material (SUS304) having a thickness of 35 μm was used as the material of the metal thin film layer 71B.

  The sliding layer 71C was coated with 20 μm of a polyimide resin mixed with 2% by mass of carbon black having an average particle size of 0.2 μm. The thermal emissivity of the sliding layer 71C was 0.95.

  As the pressing support 72, an aluminum alloy (A3004 series) was used, and the flat surface portion was roughened to Ra = 0.8 μm by a known blasting process.

  The pressure roll 73 has an outer diameter of 28 mm and a product surface hardness of JIS A / 50S (specified in JIS K6253) on the outer peripheral surface of a SUS core metal having a diameter of 16 mm. -Measured with a type A durometer type tester).

  The halogen lamp 74 is arranged at a position shifted by 8 mm from the axial center position of the fixing belt 71 in a direction close to the nip portion N, and is configured to mainly heat the nip portion N. With the halogen lamp 74 (more specifically, the filament in the halogen lamp 74) as a base point, the pressing support body 72 is arranged in a state of surrounding the central portion so as to have a central angle of 270 °.

  In the fixing device having such a configuration, the support flat portion H is 5 mm, the fixing belt outer diameter is 30 mm, the load between the pressing support 72 and the pressure roll 73 is 5 kgf (about 49 N), and the halogen is 500 W. A lamp 74 was used.

  When the time until the fixing temperature of 160 ° C. is reached as a WARM-UP time by a temperature sensor placed in the vicinity of the support on the paper entrance side is 12 seconds, it is 12 seconds, and the above-described image forming unit is at a speed of 50 mm / sec. Then, when the paper printed with black toner (J paper A4 manufactured by Fuji Xerox Co., Ltd.) was passed, no belt slip phenomenon occurred, no fixed image displacement occurred, no paper flaws occurred, and the curl was 5 mm. The following was good fixing property.

  Further, 10,000 sheets of the paper were passed by this fixing device, but no abnormality such as belt slip was observed, and almost no wear on the surface of the pressing support or the inner surface of the belt was observed. When the remaining amount of the sliding layer 71C on the inner surface of the belt was measured, 15 μm remained.

[Example 2]
The same as Example 1 except that the A3004 series aluminum substrate 60 μm was used as the metal thin film layer 71 B, and the inner peripheral surface was subjected to 15 μm high emissivity alumite treatment to form a sliding layer 71 C. A fixing belt 71 was used. The thermal emissivity of the sliding layer 71C was 0.94.

  In the fixing device having such a configuration, the support flat portion H is 5 mm, the outer diameter of the fixing belt is 30 mm, the load between the pressing support 72 and the pressure roll 73 is 5 kgf (about 49 N), and 500 W. A halogen lamp 74 was used. Unless otherwise noted, the same devices and members as those in Example 1 were used.

  When the time until the fixing temperature of 160 ° C. is reached as a WARM-UP time by a temperature sensor placed in the vicinity of the support on the paper entrance side is 12 seconds, it is 12 seconds, and the above-described image forming unit is at a speed of 50 mm / sec. Then, when the paper printed with black toner (J paper A4 manufactured by Fuji Xerox Co., Ltd.) was passed, no belt slip phenomenon occurred, no fixed image displacement occurred, no paper flaws occurred, and the curl was 5 mm. The following was good fixing property.

  In addition, although 10,000 sheets of the paper were passed by this fixing device, no abnormality such as belt slip was observed, and almost no wear was observed on the surface of the pressing support and the inner surface of the fixing belt. When the remaining amount of the sliding layer 71C on the inner surface of the fixing belt was measured, 12 μm remained.

[Example 3]
In place of the fixing device shown in FIG. 1, except for the use of the fixing device 7 shown in FIG. 6, the configuration of the fixing belt 71 and the same device as in Example 1 were used. In addition, an aramid heat-resistant felt, which is a heat-resistant fiber, is disposed as the lubricant supply member 80 on the upstream side of the plane portion on the paper entrance side of the pressing support 72 and the lubricant supply member 80 is impregnated. As a silicone oil (KF8009A: manufactured by Shin-Etsu Chemical Co., Ltd., kinematic viscosity 300 mm ² / s) was used.

  In addition, the surface of the pressing support 72 having a roughened surface with Ra = 0.5 μm was used, and the blast surface was arranged to be on the side that rubs against the fixing belt 71.

  In the fixing device having such a configuration, the support flat portion H is 12 mm, the fixing belt outer diameter is 30 mm, the load between the pressing support 72 and the pressure roll 73 is 20 kgf (about 196 N), and 700 W. A halogen lamp 74 was used.

  When the time until the fixing temperature of 165 ° C. is reached as a WARM-UP time by a temperature sensor placed in the vicinity of the support on the paper entrance side is 13 seconds, the above-mentioned image forming unit is at a speed of 200 mm / sec. When the paper printed with black toner (J paper A4 manufactured by Fuji Xerox Co., Ltd.) was passed through, no belt slip phenomenon occurred, no fixed image displacement occurred, no paper flaws occurred, and curl was less than 5 mm And good fixability.

  Further, although 100,000 sheets of the paper were passed by this fixing device, no abnormality such as belt slip was observed, and almost no wear on the surface of the pressing support and the inner surface of the belt was observed. When the remaining amount of the sliding layer 71C on the inner surface of the belt was measured, 12 μm remained.

[Example 4]
A fixing device similar to that of Example 3 was used except that the fixing belt 81 shown in FIG. 5 was used instead of the fixing belt 71 shown in FIG. In the present embodiment, a color image forming apparatus DocuCenterColor400 (manufactured by Fuji Xerox Co., Ltd.) having the same format as that in FIG. 7 was used.

  As the fixing belt 81 shown in FIG. 5, here, the sliding layer 81C and the metal thin film layer 81B on the inner surface of the belt are the same as the sliding layer 71C and the metal thin film layer 71B in the first embodiment, respectively, and the outside of the metal thin film layer 81B. 200 μm of silicone rubber layer 71D is coated with a primer layer (DY39-051: manufactured by Toray Dow Corning Silicone Co., Ltd.) not shown, and 30 μm of PFA-TUBE (Gunze (Gunze ( Co., Ltd.).

  In the fixing device having such a configuration, the support flat portion H is 12 mm, the outer diameter of the fixing belt 81 is 30 mm, the load between the pressing support 72 and the pressure roll 73 is 20 kgf (about 196 N), A 700 W halogen lamp 74 was used.

  When the time until the fixing temperature of 165 ° C. is reached as a WARM-UP time by a temperature sensor placed in the vicinity of the support on the paper entrance side is 17 seconds, the above-mentioned image forming unit is at a speed of 200 mm / sec. The paper (Fuji Xerox Co., Ltd., J4 A4) printed with 4-color toner was passed through, no belt slip phenomenon occurred, no fixed image displacement occurred, no paper flaws occurred, and no curling It was 5 mm or less, and the fixing property was good.

  Further, although 100,000 sheets of the paper were passed by this fixing device, no abnormality such as belt slip was observed, and almost no wear on the surface of the pressing support and the inner surface of the belt was observed. When the remaining amount of the sliding layer 81C on the inner surface of the belt was measured, 13 μm remained.

  As described above, in the fixing device according to the present exemplary embodiment, the WARM-UP time is not significantly increased, and the linear velocity between the fixing belt 81 and the pressure roll 73 in the nip portion N is not different. . For this reason, even when a recording medium having a multilayer structure such as an envelope is applied to the recording medium P, for example, an ordinary sheet is used, wrinkles and curls are not generated, and transportability and fixing properties are improved. In addition, it is possible to realize higher instant start performance and excellent high-speed aptitude, and overload to the motor due to an increase in sliding resistance or fixing failure due to belt slip phenomenon (image misalignment, unevenness, etc.) ) Can be prevented.

[Comparative Example 1]
In the fixing belt 71 shown in FIG. 4, when the same apparatus as in Example 1 was used except that the sliding layer 71C was not provided on the inner surface, the WARAM-UP time was 25 seconds, and the speed was 50 mm / sec. When the paper (Fuji Xerox J paper A4) printed with black toner was passed through the image forming section, a belt slip phenomenon occurred, and the printed image was also displaced.

  In addition, the drive torque increased after 2000 sheets were passed, and many wear powders mainly composed of the constituent components of the metal thin film layer 71B were generated on the surface of the pressing support 72. Further, when the paper is continuously passed, the wear powder bites into the nip portion N, so that the metal thin film layer 71B is plastically deformed and unevenness is generated.

[Comparative Example 2]
The fixing belt 71 shown in FIG. 4 has the same configuration and conditions as in Example 3 except that the sliding layer 71C is not provided on the inner surface.

  As a result, when a paper (J paper A4 manufactured by Fuji Xerox Co., Ltd.) printed with black toner is passed through the image forming unit at a speed of 200 mm / sec, a belt slip phenomenon occurs and a fixed image shift occurs. Oops. In addition, the drive torque increased from the time when 5000 sheets were passed, and a lot of wear powder mainly composed of the constituent components of the metal thin film layer 71B was generated on the surface of the pressing support 72.

[Comparative Example 3]
The fixing belt 81 shown in FIG. 5 has the same configuration and conditions as in Example 4 except that the sliding layer 81C is not provided on the inner surface.

  As a result, when a sheet (Fuji Xerox J-sheet A4) printed with four-color toner is passed through the image forming unit at a speed of 200 mm / sec, a belt slip phenomenon occurs and a fixed image shift occurs. have done. In addition, the drive torque increased from the time when 5000 sheets were passed, and a lot of wear powder mainly composed of the constituent components of the metal thin film layer 71B was generated on the surface of the pressing support 72.

  The present invention is not limited to a black and white image fixing device, and can be used in a high image density image forming apparatus such as a color image fixing device by including an elastic layer in an endless belt used as a fixing belt. It is. Further, for example, by applying the configuration as shown in FIG. 6, it can be used in an image forming apparatus that requires high-speed operation.

1 is a schematic cross-sectional view illustrating a fixing device according to a first embodiment which is an example of a fixing device of the present invention. FIG. 2 is a schematic configuration diagram of an image forming apparatus including the fixing device of FIG. 1. FIG. 2 is a front view of a halogen lamp (heat source) 74 in the fixing device of FIG. 1. FIG. 4 is a schematic enlarged cross-sectional view of a fixing belt in fixing devices of first, second, and third embodiments that are examples of the fixing device of the present invention. FIG. 6 is a schematic enlarged cross-sectional view showing a fixing belt according to a fourth embodiment which is an example of a fixing device of the present invention. FIG. 6 is a schematic cross-sectional view illustrating a fixing device according to a third embodiment which is an example of a fixing device according to the present invention. FIG. 2 is a schematic configuration diagram illustrating an example of a color image forming apparatus including the fixing device of FIG. 1. It is a schematic cross-sectional view showing an example of a conventional fixing device.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 Photosensitive drum (latent image carrier), 2 charging roll (charging means), 3 image exposure device (electrostatic latent image forming means), 4 developing device (developing means), 5 transfer roll (transfer means), 6 cleaner (Cleaning member), 7 fixing device, 68 pressing support, 70 lamp tube, 71, 81 fixing belt (endless belt), 71A, 81A release layer, 71B, 81B metal thin film layer (metal substrate layer), 71C, 81C Sliding layer, 72 pressure support, 73 pressure roll, 74 halogen lamp (heat source), 75 coating part, 79 filament, 80 lubricant supply member, 81D elastic layer, 82 heat source, 90 fixing device, 91 pressure roll, 92 heat resistant endless belt, 220 color image forming apparatus, 401a, 401b, 401c, 401d electrophotographic photosensitive member, 402a, 402 b, 402c, 402d Charging roll, 403 Laser light source (exposure device), 404a, 404b, 404c, 404d Developing device, 405a, 405b, 405c, 405d Toner cartridge, 406 Drive roll, 407 Tension roll, 408 Backup roll, 409 Intermediate Transfer belt, 410a, 410b, 410c, 410d primary transfer roll, 411 tray (transfer medium tray), 412 transfer roll, 413 secondary transfer roll, 414 fixing device, 415a, 415b, 415c, 415d, 416 cleaning blade, 420 Housing, 500 Medium to be transferred.

Claims (4)

An endless belt having a first layer of a metallic substrate extending in a tubular shape,
An endless belt, further comprising a second layer having a thermal emissivity of 0.9 or more on an inner peripheral surface side of the first layer. A pressure roll for rotational driving;
An endless belt that rotates in contact with the pressure roll;
A pressing support for pressing the endless belt from the inside;
A heat source disposed in the circumference of the endless belt,
In an endless belt used in a fixing device that heats the endless belt by radiant heat from the heat source and heat conduction through the pressing support,
The endless belt is
Having a first layer of a metallic substrate extending in a tubular shape;
An endless belt, further comprising a second layer having a thermal emissivity of 0.9 or more on a surface that rubs against the pressing support. A pressure roll for rotational driving;
An endless belt that rotates in contact with the pressure roll;
A pressing support for pressing the endless belt from the inside;
A heat source disposed within a circumference of the endless belt,
The endless belt is
Having a first layer of a metallic substrate extending in a tubular shape;
A second layer having a thermal emissivity of 0.9 or more is further provided on the surface that rubs against the pressing support,
The fixing device, wherein the endless belt is heated by radiant heat from the heat source and heat conduction through the pressing support. Charging means for charging the surface of the image carrier;
An electrostatic latent image forming means for forming an electrostatic latent image according to image information on the surface of the charged image carrier;
Developing means for developing a toner image by developing the electrostatic latent image formed on the surface of the image carrier with toner;
Transfer means for transferring the toner image formed on the surface of the image carrier to the surface of a recording medium;
Fixing means for fixing the toner image transferred to the surface of the recording medium, and an image forming apparatus comprising at least
The fixing means is
A pressure roll for rotational driving;
An endless belt that rotates in contact with the pressure roll;
A pressing support for pressing the endless belt from the inside;
A heat source disposed in the circumference of the endless belt,
The endless belt is
Having a first layer of a metallic substrate extending in a tubular shape;
A second layer having a thermal emissivity of 0.9 or more is further provided on the surface that rubs against the pressing support,
An image forming apparatus, wherein the endless belt is heated by radiant heat from the heat source and heat conduction through the pressing support.

Images