JP2017125922A - Fixing device and image forming apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a fixing device that can maintain a low slide resistance between a nip forming member and a fixing belt and maintain high soaking performance, and an image forming apparatus.SOLUTION: There is provided a fixing device comprising: an endless fixing belt 21 that is provided rotatably; a pressure roller 22 that is provided rotatably and applies pressure to the fixing belt 21 from an outer peripheral side; a nip forming member 24 that is located on an inner peripheral side of the fixing belt 21, in contact with the fixing belt 21 with a soaking member 29 formed of a highly heat conductive metal therebetween, and forms a fixing nip part N between the fixing belt 21 and pressure roller 22; and a halogen heater 23 that heats the fixing belt 21, wherein a dispersed plating coating 40 of a fluorine resin is formed on a surface of the soaking member 29 facing an inner peripheral surface of the fixing belt 21.SELECTED DRAWING: Figure 2

Description

  The present invention relates to a fixing device of an image forming apparatus using an electrophotographic system such as a copying machine, a printer, a facsimile machine, or a multifunction machine thereof, and more specifically, fixes a fixed image through an endless belt, a film, and a roller. The present invention relates to a fixing device and an image forming apparatus.

  In an image forming apparatus such as a copying machine, a printer, or a facsimile, a toner image is formed on an image carrier based on image information, and the toner image is transferred onto a recording medium such as paper or an OHP sheet. Thereafter, the unfixed toner image carried on the recording medium is fixed on the recording medium by the fixing device.

  The fixing device is provided with a fixing rotator constituted by opposing rollers or belts, or a combination thereof. A recording sheet as a recording medium is sandwiched at a nip portion, and a toner image is placed on the recording sheet by heat and pressure. To settle.

  In particular, the nip forming member that contacts the fixing belt on the inner peripheral side of the fixing belt forms a fixing nip portion between the fixing belt and the pressure roller, and slides between the nip forming member and the fixing belt. A configuration for forming a nip portion is known.

  According to Non-Patent Document 1, the sliding nip portion is widely used even in a high-speed machine having a productivity of 100 A4 size prints / min.

  Further, in Non-Patent Document 2, the durability of 80 sheets / min is ensured by sliding between SUS (stainless steel) which is a high hardness metal and polyimide. Since the thermal conductivity of SUS is the worst among metals, it is about 10 to 20 W / mK, so that the heat uniformity of the fixing belt is achieved by the IH heater and the magnetic shielding plate.

  However, in the fixing device disclosed in Non-Patent Documents 1 and 2, if the sliding resistance between the nip forming member and the fixing belt is large, the fixing belt does not rotate with the pressure roller and slips. It may happen. When such a slip occurs, the recording medium stops and an excessive amount of heat is generated, thereby causing a hot offset. In addition, the temperature distribution of the fixing belt itself becomes abnormal, and the fixing quality deteriorates.

  SUMMARY OF THE INVENTION The present invention has been made to solve such a conventional problem, and is a fixing device and an image forming apparatus that can keep the sliding resistance between the nip forming member and the fixing belt low and maintain high heat equalization performance. The purpose is to provide.

  In order to solve the above problems, a fixing device according to the present invention includes an endless fixing belt that is rotatably provided, a pressure member that is rotatably provided and pressurizes the fixing belt from an outer peripheral side, A nip formed on the inner peripheral side of the fixing belt and in contact with the fixing belt through a heat equalizing member made of a metal having high heat conductivity, and forming a fixing nip portion between the fixing belt and the pressure member And a heat source for heating the fixing belt, and a dispersion plating film of fluororesin is formed on a surface of the soaking member facing the inner peripheral surface of the fixing belt.

  The present invention provides a fixing device and an image forming apparatus that can keep the sliding resistance between the nip forming member and the fixing belt low and maintain high heat equalization performance.

1 is a schematic configuration diagram of an image forming apparatus including a fixing device according to an embodiment of the present invention. 1 is a cross-sectional view illustrating a configuration of a fixing device according to an embodiment of the present invention. It is a characteristic view which shows the temperature rise of the glass tube surface of a halogen heater at the time of using argon gas and xenon gas as an inert gas in a halogen heater. FIG. 6 is a cross-sectional view illustrating another configuration of the fixing device according to the embodiment of the present invention. FIG. 10 is a cross-sectional view showing still another configuration of the fixing device according to the embodiment of the present invention.

  Embodiments of the present invention will be described below with reference to the drawings.

  FIG. 1 is a diagram illustrating a schematic configuration of an image forming apparatus including a fixing device according to an embodiment of the present invention, and illustrates an example in which the image forming apparatus is applied to a color laser printer.

  In FIG. 1, the image forming apparatus 1 includes a bottle storage unit 2, a transfer device 3, four image forming units 4 </ b> Y, 4 </ b> M, 4 </ b> C, and 4 </ b> K, a paper feeding unit 10, and a fixing device 20. .

The four image forming units 4Y, 4M, 4C, and 4K are provided in the center of the apparatus main body of the image forming apparatus 1. Each of the image forming units 4Y, 4M, 4C, and 4K contains developers of different colors of yellow (Y), magenta (M), cyan (C), and black (K) corresponding to the color separation components of the color image. The configuration is the same except that.
Specifically, each of the image forming units 4Y, 4M, 4C, and 4K has a drum-shaped photoconductor 5 as a latent image carrier, a charging device 6 that charges the surface of the photoconductor 5, and a surface of the photoconductor 5. A developing device 7 that supplies toner and a cleaning device 8 that cleans the surface of the photoreceptor 5 are provided. In FIG. 1, only the photoconductor 5, the charging device 6, the developing device 7, and the cleaning device 8 included in the black image forming unit 4 </ b> K are denoted by reference numerals. The reference numerals are omitted.

  Under the image forming units 4Y, 4M, 4C, and 4K, an exposure device 9 that exposes the surface of the photoreceptor 5 is disposed. The exposure device 9 includes a light source, a polygon mirror, an f-θ lens, a reflection mirror, and the like, and irradiates the surface of each photoconductor 5 with laser light based on image data.

  A transfer device 3 is disposed above the image forming units 4Y, 4M, 4C, and 4K. The transfer device 3 includes an intermediate transfer belt 30 as a transfer body, four primary transfer rollers 31 as primary transfer means, and a secondary transfer roller 36 as secondary transfer means. Further, the transfer device 3 includes a secondary transfer backup roller 32, a cleaning backup roller 33, a tension roller 34, and a belt cleaning device 35.

  The intermediate transfer belt 30 is an endless belt and is stretched by a secondary transfer backup roller 32, a cleaning backup roller 33, and a tension roller 34. Here, when the secondary transfer backup roller 32 is driven to rotate, the intermediate transfer belt 30 runs (rotates) in the direction indicated by the arrow in FIG.

  Each of the four primary transfer rollers 31 sandwiches the intermediate transfer belt 30 with each photoconductor 5 to form a primary transfer nip. Each primary transfer roller 31 is connected to a power source, and a predetermined direct current voltage (DC) and / or alternating current voltage (AC) is applied to each primary transfer roller 31.

  The secondary transfer roller 36 sandwiches the intermediate transfer belt 30 with the secondary transfer backup roller 32 to form a secondary transfer nip. Similarly to the primary transfer roller 31, a power source is connected to the secondary transfer roller 36 so that a predetermined direct current voltage (DC) and / or alternating current voltage (AC) is applied to the secondary transfer roller 36. It has become.

  The belt cleaning device 35 includes a cleaning brush and a cleaning blade disposed so as to contact the intermediate transfer belt 30. The waste toner transfer hose extending from the belt cleaning device 35 is connected to the entrance of the waste toner container.

  A bottle container 2 is provided in the upper part of the printer main body, and four toner bottles 2Y, 2M, 2C, and 2K containing replenishing toner are detachably attached to the bottle container 2. A replenishment path is provided between each toner bottle 2Y, 2M, 2C, 2K and each developing device 7, and each toner bottle 2Y, 2M, 2C, 2K is connected to each developing device 7 via this replenishment path. The toner is replenished.

  A lower part of the printer main body is provided with a paper feeding unit 10 that stores a recording medium P such as transfer paper, a paper feeding roller 11 that carries the recording medium P out of the paper feeding unit 10, and the like. Here, the recording medium P includes, in addition to plain paper, thick paper, postcards, envelopes, thin paper, coated paper (coated paper, art paper, etc.), tracing paper, OHP sheet, and the like. A manual paper feed mechanism may be provided.

  In the printer main body, a conveyance path R is provided for discharging the recording medium P from the paper supply unit 10 through the secondary transfer nip to the outside of the apparatus. As conveying means for conveying the recording medium P to the secondary transfer nip, in the conveying path R, upstream of the position of the secondary transfer roller 36 in the conveying direction of the recording medium P (hereinafter simply referred to as “conveying direction”). A pair of registration rollers 12a and 12b is provided.

  Further, a fixing device 20 for fixing the unfixed image transferred to the recording medium P is disposed on the downstream side in the transport direction from the position of the secondary transfer roller 36. Further, a pair of paper discharge rollers 13 a and 13 b for discharging the recording medium to the outside of the apparatus is provided downstream of the fixing device 20 in the conveyance direction of the conveyance path R. A discharge tray 14 for stocking the recording medium P discharged outside the apparatus is provided on the upper surface of the printer main body.

  FIG. 2 is a diagram illustrating the configuration of the fixing device 20.

  As shown in FIG. 2, the fixing device 20 includes a fixing belt 21, a pressure roller 22, a halogen heater 23 as a heat source, a nip forming member 24, a stay 25 as a support member, a reflecting member 26, A separation member 28 and a soaking member 29 are provided.

  The fixing belt 21 is a thin and flexible endless belt (or film), and is provided so as to be rotatable in the direction of the arrow in FIG. Here, the endless shape means a state in which both ends of the belt are joined and no joint exists.

  The fixing belt 21 has a thin and small-diameter laminated structure in order to reduce the heat capacity, and a base material layer and a release layer are sequentially laminated from the inner peripheral surface side, and the total thickness is The diameter is set to 1 mm or less, and the diameter is set to 20 to 40 mm. This is an exemplification, and the present invention is not limited to this.

  The base material layer of the fixing belt 21 has a layer thickness of 20 to 50 μm. For example, a metal material such as nickel or SUS (stainless steel), or a resin material such as polyimide (PI) or polyamideimide (PAI) is used. It is formed. This is an exemplification, and the present invention is not limited to this.

  The release layer of the fixing belt 21 has a layer thickness of 10 to 50 μm and is formed of a material such as ethylene tetrafluoride / perfluoroalkyl vinyl ether copolymer resin (PFA) or tetrafluoroethylene resin (PTFE). Yes. By providing such a release layer, the fixing belt 21 is secured with respect to the toner image T on the recording medium P. This is an exemplification, and the present invention is not limited to this. Moreover, the mold release means that the bonded objects are peeled off, and the mold release property means the ease of peeling between the objects.

  There may be an elastic layer formed of silicone rubber or the like between the base material layer and the release layer of the fixing belt 21. When there is no elastic layer, the heat capacity is reduced and the fixability is improved. However, when the unfixed image is crushed and fixed at the fixing nip N, minute irregularities on the belt surface are transferred to the image and the image is solid. There is a possibility that a defect in which luster unevenness (coconut skin image) remains on the part remains. Here, the cocoon skin image means an image in which a number of minute irregularities are formed on the surface. In order to improve this, an elastic layer of silicone rubber is provided to 100 μm or more. Due to the deformation of the elastic layer, minute irregularities are absorbed, and the cocoon skin image can be improved.

  The pressure roller 22 is a roller having a diameter of about 20 to 40 mm provided so as to contact the outer peripheral surface of the fixing belt 21 at the position of the fixing nip portion N and press the fixing belt 21 from the outer peripheral side. In the pressure roller 22, an elastic layer 22b is formed on a core bar 22a having a heat-resistant solid structure, and a thin release layer 22c is formed on the surface of the elastic layer 22b. This is an exemplification, and the present invention is not limited to this.

  The pressure roller 22 is pressed against the fixing belt 21, the heat equalizing member 29, and the nip forming member 24 by a pressure mechanism such as a spring, so that the elastic layer 22b is crushed. Thereby, in the fixing device 20, a desired fixing nip portion N in which the recording medium P is conveyed is formed between the pressure roller 22 and the fixing belt 21.

  The pressure roller 22 is rotationally driven in a direction indicated by an arrow in FIG. 2 by a driving mechanism such as a motor provided in the image forming apparatus main body, and transmits a driving force to the fixing belt 21 at the fixing nip portion N. Is driven to rotate.

  The elastic layer 22b of the pressure roller 22 is formed of a material such as foamable silicone rubber, silicone rubber, or fluororubber, and has a thickness set to 100 μm or more. Further, the release layer 22c of the pressure roller 22 is formed of a material such as PFA or PTFE. This is an exemplification, and the present invention is not limited to this.

  Since the elastic layer 22b has a thickness of 100 μm or more, the fixing device 20 absorbs minute irregularities on the surface of the fixing belt 21 due to elastic deformation of the elastic layer 22b and fixes the color image on the recording medium P. Generation of a skin image can be prevented.

  The pressure roller 22 may be a hollow roller, and may have a heat source such as a halogen heater inside the pressure roller 22. The elastic layer 22b may be solid rubber, but if there is no heater inside the pressure roller 22, sponge rubber may be used. Use of sponge rubber is more preferable because heat insulation is enhanced and heat of the fixing belt 21 is not easily taken.

  Both ends of the halogen heater 23 are fixed to the side plate of the fixing device 20 and are configured to generate heat when output is controlled by a power supply unit provided in the printer body. The halogen heater 23 includes a halogen lamp in which a gas mainly containing xenon or krypton as an inert gas is enclosed in a glass tube. Xenon and krypton are gases having a higher molecular weight than argon.

  The halogen heater 23 is provided in the fixing belt 21 so as to face a reflection member 26 described later, and directly heats the fixing belt 21 from the inner peripheral side at a place other than the fixing nip portion N by generating radiant heat. It is configured as follows.

  As a result, the fixing device 20 improves the heating efficiency of the fixing belt 21 by the halogen heater 23, so that it is excellent in energy saving and can shorten the first print time. The first print time means a time required for printing the first sheet on the recording medium P after receiving the print start instruction and discharging the recording medium P to the outside of the image forming apparatus 1.

  In addition to the halogen heater 23, an IH heater, a resistance heating element, a carbon heater, or the like can be used as a heat source for heating the fixing belt 21.

  The nip forming member 24 is disposed so as to contact the pressure roller 22 from the inner peripheral side of the fixing belt 21 and form a fixing nip portion N between the fixing belt 21 and the pressure roller 22. The nip forming member 24 is non-rotating, contacts the inner peripheral surface of the fixing belt 21 via a heat equalizing member 29 described later, and slides indirectly with the inner peripheral surface of the fixing belt 21. .

  In order to reduce wear between the fixing belt 21 and the nip forming member 24, fluorine oil or fluorine grease containing a fluorine compound as a lubricant is applied to the inner peripheral surface of the fixing belt 21. The lubricant may be fluorine grease or silicone grease using fluorine particles as a thickener.

  In the configuration of FIG. 2, the shape of the fixing nip N is flat, but may be a concave shape or other shapes. When the concave fixing nip portion N is formed, the discharge direction of the leading end of the recording medium is closer to the pressure roller 22 and the separation of the recording medium P from the fixing belt 21 is improved. The

  Since the shape of the nip forming member 24 is complicated, it is desirable that the nip forming member 24 is an injection-molded product of heat-resistant resin. Examples of the heat-resistant resin include LCP (heat-resistant temperature of about 330 ° C.) and PEK (heat-resistant temperature of about 350 ° C.). desirable. This is an exemplification, and the present invention is not limited to this.

  Since the nip forming member 24 is made of a heat-resistant resin material, the fixing device 20 can prevent the deformation of the nip forming member 24 due to heat in the toner fixing temperature region and ensure a stable state of the fixing nip portion N. The output image quality can be stabilized.

  The nip forming member 24 is provided such that the axial direction of the fixing belt 21 is the longitudinal direction, and a contact portion 24b protruding from the base portion 24a in the thickness direction of the recording medium P (hereinafter simply referred to as “thickness direction”). Is fixedly supported by the stay 25 by contacting the stay 25.

  By fixing and supporting the nip forming member 24 to the stay 25, the fixing device 20 is prevented from being bent by the pressure by the pressure roller 22, and has a uniform nip width in the longitudinal direction. Can be obtained.

  The nip forming member 24 is formed smaller than the stay 25 in order to ensure the mechanical strength of the stay 25.

  Furthermore, it is assumed that a protrusion is formed on the nip exit side of the nip forming member 24. This protruding portion is not in contact with the pressure roller 22 via the fixing belt 21, and the recording medium P after fixing at the fixing nip portion N is lifted from the fixing belt 21, thereby improving the separation of the recording medium P. It is something to enhance.

  The stay 25 reinforces and supports the nip forming member 24 that forms the fixing nip portion N, and is held and fixed to the side plate at both ends in the axial direction and positioned. The stay 25 comes into contact with the pressure roller 22 via the nip forming member 24, the heat equalizing member 29, and the fixing belt 21, so that the nip forming member 24 receives the pressure of the pressure roller 22 at the fixing nip portion N. Therefore, the occurrence of defects that cause large deformations is suppressed.

  The stay 25 is preferably formed of a metal material having high mechanical strength such as stainless steel or iron alloy in order to satisfy the above-described function, but may be formed of a resin material.

  The reflection member 26 is fixed between the stay 25 and provided between the stay 25 and the halogen heater 23. The reflecting member 26 is a concentric circle centering on the halogen heater 23 that reflects the radiant heat and radiant light (hereinafter simply referred to as “radiant heat”) emitted from the halogen heater 23 toward the reflecting member 26 toward the fixing belt 21. The reflecting surface 26a is formed on the surface. Further, since the reflecting member 26 is directly heated by the halogen heater 23, the reflecting member 26 is formed of a metal material having a high melting point.

  The reflection surface 26a of the reflection member 26 has a reflectance set to 90% or more. In addition, this is an illustration and this invention is not limited to this.

  By providing the reflection member 26, the fixing device 20 can increase the radiant heat applied to the fixing belt 21, and can efficiently heat the fixing belt 21. Further, since the fixing device 20 can suppress the radiant heat from the halogen heater 23 from being transmitted to the stay 25 and the like, energy saving can be achieved. Here, instead of providing the reflecting member 26, the same effect can be obtained by subjecting the surface of the stay 25 to heat insulation treatment or mirror treatment.

  The separation member 28 is fixed to the fixing device 20 and separates the recording medium P from the surface of the fixing belt 21 by coming into contact with the recording medium P on which the color image is fixed at the fixing nip N.

  The soaking member 29 is made of a metal material having high thermal conductivity such as copper, aluminum, or an aluminum alloy.

  Here, FIG. 3 shows the temperature rise characteristics of the glass tube surface of the halogen heater 23 when the inert gas in the halogen heater 23 is replaced with xenon gas instead of the conventionally used argon gas. In this experimental result, the argon gas exceeds 400 ° C. after 110 seconds from the start of fixing, but in the case of xenon gas, the temperature changes around 350 ° C. after 110 seconds from the start of fixing, and hydrofluoric acid is generated. It is kept at 400 ° C. or lower. In the heat generation mechanism in the halogen heater, when an inert gas is sealed in the space in the glass tube, evaporation of tungsten used as a filament is suppressed by the pressure. Furthermore, the evaporated tungsten collides with the inert gas molecules and cannot go straight, and the tungsten vapor pressure around it increases. Thereby, the evaporation of tungsten is suppressed and the life is extended.

  This effect is greater for gases with higher molecular weights, and for gases with higher molecular weights, convection is less likely to occur and less heat is taken from the filament, so heat transfer to the glass tube via an inert gas is less likely to occur. It is thought that the temperature of the glass tube is difficult to rise. Inert gases used as halogen heaters are helium, neon, argon, krypton, xenon, and radon from the lighter side, and krypton and further xenon have higher performance than conventional argon. By using a gas having a large molecular weight as the inert gas sealed in the glass tube of the halogen heater 23, the temperature rise of the glass tube can be suppressed, and the hydrogen fluoride when the halogen heater control becomes impossible and the temperature runs away. Generation of acid can be suppressed. Note that radon is not used because it is a radioactive gas with a short half-life and is not practical.

  In the present embodiment, a dispersion plating film 40 in which a fluororesin (PTFE particles of about 0.2 to 0.5 μm) is dispersed in a Ni—P matrix is coated with a soaking member 29 that faces the inner peripheral surface of the fixing belt 21. Formed on the surface. Ni-P is a typical matrix in dispersion plating with a fluororesin.

  Further, after the dispersion plating film 40 is plated, a Vickers hardness of the dispersion plating film 40 is 10 to 30% by performing a heat curing process (amorphous structure → precipitation hardening by crystallization) at 280 to 320 ° C. for about 1 hour. As a result, the durability was improved. The PTFE content can be set in the range of 0.5 to 10 wt%, etc. If the low friction property is emphasized, the PTFE content is increased. If the durability is important, the PTFE content is decreased. Good.

  In addition to polymer solid lubricants such as fluororesins, carbons such as graphite, fullerene (C60), carbon nanotubes (CNT), and nanodiamonds (ND) can be used to impart abrasion resistance to the plating film. System materials are considered. In particular, ND (5 to 50 nm in diameter) is excellent in hardness, thermal conductivity, and lubricity, and therefore, these excellent characteristics are imparted to the dispersion plating film 40 by being eutectoid in the dispersion plating film 40. be able to.

  In addition, since the dispersion plating film 40 is made of a metal matrix, the volume resistance is about 90 μΩ · cm, and static electricity and the like can be reliably removed by grounding the soaking member 29 as a base material. Although the float metal may become an antenna and generate high-frequency electromagnetic noise, the dispersion plating film 40 in the present embodiment does not cause such a problem due to the grounding of the soaking member 29. It has become.

  Further, the contact angle with respect to the dispersion plating film 40 was measured by comparison between fluorine oil and silicone oil. When both oils were dropped onto the dispersion plating film, the difference between the contact angles was 40 degrees and 44 degrees, but after 5 seconds the fluorine oil was 17 degrees and the silicone oil remained unchanged. It became remarkable that the wettability of the dispersed plating film 40 containing fluorine and fluorine oil was good.

  Table 1 shows sliding durability when various conditions are changed regarding the material of the fixing belt 21, the material of the surface of the soaking member 29, the material of the soaking member 29, and whether or not the lubricant is applied to the fixing belt 21. The results of measuring the properties, the temperature of the non-sheet passing portion of the fixing belt 21, and the presence or absence of hydrofluoric acid were shown. Examples 1 to 13 in the table are examples relating to the fixing device 20 of the present embodiment. According to these Examples 1 to 13, it was possible to obtain long-term sliding durability of up to 600,000 sheets while suppressing an increase in the temperature of the non-sheet passing portion in the fixing belt 21.

  The presence or absence of hydrofluoric acid is confirmed by hitting the fixing belt 21 immediately after the continuous passage of 10 minutes or 30 minutes to generate scattering of fluorine oil and the like, and a micro detection tube capable of detecting 0.03 ppm is used as the belt. Evaluation was made close to the edge. Note that the reference value for the concentration of hydrofluoric acid, which is considered dangerous, is 2 ppm according to the American Industrial Hygienists Conference. In all of the examples in Table 1, a halogen heater having a filament color temperature of 2400 ± 200 K using krypton and xenon as an enclosed gas is used.

When a halogen heater using argon as an enclosed gas was used as a heat source, 0.5 ppm of hydrofluoric acid was detected immediately after 30 minutes of continuous paper feeding. Further, a similar experiment was performed with the coil of the IH heater as the heat source arranged outside the fixing belt 21, but generation of hydrofluoric acid was not confirmed.

  Hereinafter, another configuration example of the fixing device 20 will be described.

  The fixing device 20 shown in FIG. 4 differs from the fixing device shown in FIG. 2 only in that the heat source is composed of three halogen heaters 23a, 23b, and 23c. The same reference numerals are assigned to the same members, and repeated description is omitted. By increasing the number of halogen heaters 23, fixing corresponding to various paper widths of the recording medium P can be performed without reducing productivity. Also in the fixing device 20 of FIG. 4, the inert gas used in the halogen heaters 23a, 23b, and 23c is a gas mainly composed of xenon and krypton. Further, a protrusion 27 is formed on the nip exit side of the nip forming member 24. The protrusion 27 is not in contact with the pressure roller 22 via the fixing belt 21 and improves the separation of the recording medium P.

  In the fixing device 20 shown in FIG. 5, the heat source is composed of two halogen heaters 23a and 23b as compared with the fixing device shown in FIG. Also in the fixing device 20 of FIG. 5, the inert gas used in the halogen heaters 23a and 23b is a gas mainly composed of xenon and krypton.

  As described above, in the fixing device of the present embodiment, since the dispersion plating film 40 of fluororesin is formed on the surface of the soaking member 29, excellent sliding durability is obtained and the soaking member 29 is provided. Therefore, it is possible to maintain high soaking performance. Further, since the sliding resistance between the nip forming member 24 and the fixing belt 21 is sufficiently low, the slip between the fixing belt 21 and the pressure roller 22 can be prevented. In addition, by configuring the heat equalizing member 29 with a metal having high heat conductivity, it is possible to suppress the temperature rise of the non-sheet passing portion of the fixing belt 21.

  Further, the fixing device according to the present embodiment can realize further excellent sliding durability by precipitation hardening by crystallization of Ni—P which is a matrix of the dispersion plating film 40.

  In the fixing device of the present embodiment, a lubricant containing a fluorine compound having the same chemical bond as that of the fluororesin contained in the dispersion plating film 40 and having the same solubility parameter is used as the fixing belt 21 and the nip forming member 24. The sliding part is maintained with good wettability. Therefore, the sliding resistance is reduced, and the nip forming member 24 and the fixing belt 21 can be slid with low torque.

  Further, in the fixing device of the present embodiment, even when the halogen heater 23 runs away, the temperature of the glass tube surface of the halogen heater 23 is reduced by the effect of the sealed gas having a lower thermal conductivity than the widely used inert gas argon. Can be suppressed. Thereby, even when a lubricant such as fluorine oil adheres to the surface of the glass tube of the halogen heater 23, the possibility that hydrofluoric acid is generated can be reduced.

  Further, in the fixing device of the present embodiment, even when an IH heater as a heat source runs away, there is no possibility that a lubricant such as fluorine oil will come into contact with a member exceeding 400 ° C., and hydrofluoric acid may be generated. Can be reduced.

  Further, in the fixing device of the present embodiment, the electric resistance of the dispersion plating film 40 formed on the surface of the sliding portion between the fixing belt 21 and the nip forming member 24 is low, and the soaking member 29 is grounded. Yes. For this reason, generation | occurrence | production of the static electricity in the peripheral part of the nip formation member 24, generation | occurrence | production of EMI (ElectroMagnetic Interference), etc. can be prevented.

  In addition, the image forming apparatus according to the present embodiment can form the fixing nip portion N having any shape and width by mounting the fixing device 20. For example, the shape and width of the nip forming member 24 can be configured so as to optimize the amount of heat supplied from the heat source to the nip forming member 24, and the heating temperature of the fixing belt 21 can be lowered. Thereby, it is possible to reduce the release amount of chemical substances (VOC, UFP) at the time of image formation, and to suppress deterioration due to the temperature effect of the fixing belt 21 and the like. Further, the curl of the recording medium P can be suppressed by setting the curvature shape of the surface of the nip forming member 24 that contacts the fixing belt 21 to be opposite to the curl of the recording medium P.

  Although the preferred embodiment of the present invention has been described above, the present invention is not limited to the above-described embodiment. The present invention can be variously modified or changed in light of the appended claims.

DESCRIPTION OF SYMBOLS 1 Image forming apparatus 20 Fixing apparatus 21 Fixing belt 22 Pressure roller (Pressure member)
23, 23a, 23b, 23c Halogen heater (heat source)
24 Nipping member 29 Heat equalizing member 40 Dispersion plating film N Fixing nip

"Versant 2100 Press-Realizing high productivity in a compact manner", Japanese Imaging Society 2014 Symposium "Current Status of Digital Printing and Latest Electrophotographic Technology" Proceedings "High-speed technology for color on-demand fixing devices", Imaging Conference JAPAN, 2013, p. 241-244

Claims (7)

An endless fixing belt provided rotatably;
A pressure member that is rotatably provided and pressurizes the fixing belt from an outer peripheral side;
A nip located on the inner peripheral side of the fixing belt and in contact with the fixing belt through a heat-uniforming member made of a metal having high heat conductivity, and forming a fixing nip portion between the fixing belt and the pressure member. A forming member;
A heat source for heating the fixing belt,
A fixing device, wherein a dispersion plating film of a fluororesin is formed on a surface of the heat equalizing member facing an inner peripheral surface of the fixing belt.   The fixing device according to claim 1, wherein the dispersion plating film is obtained by dispersing a fluororesin in a Ni—P matrix and precipitation hardening at 280 to 320 ° C.   The fixing device according to claim 1, wherein a lubricant is applied to an inner peripheral side of the fixing belt, and the lubricant contains a fluorine compound.   The fixing device according to claim 3, wherein the heat source is a halogen heater provided with a halogen lamp, and an enclosed gas of the halogen lamp is mainly composed of xenon and krypton.   The fixing device according to claim 3, wherein the heat source is an IH heater.   The fixing device according to claim 1, wherein the heat equalizing member is grounded.   An image forming apparatus comprising the fixing device according to claim 1.

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