JP2008151857A - Heat fixing device and image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a fixing unit configuration for reducing the variation of fixability within a page and enhancing gloss. <P>SOLUTION: The heat fixing device is configured so that pressure is partially applied to the downstream side of a nip in a heater. A member for applying pressure is composed of a member independent of the heater and has elasticity. A heating body has a hollow structure, expands by the application of heat, and applies pressure. As another configuration, a configuration for partially applying pressure to the downstream side is integrated with the heating body and formed from an elastic body. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a heat fixing device for heating a member to be heated to a predetermined level, and more particularly to an image forming apparatus such as an electrophotographic copying machine or an electrophotographic printer.

  In general, in various types of information, video equipment, and the like, an image forming apparatus that specifically substantiates an image in an intangible information format on a recording material such as paper is used as its final output form.

  In such an image forming apparatus such as a copying machine, a coloring agent or the like is fixed on a recording material according to an image pattern by drawing or drawing, scanning or recording an object, or generating an image generated by communication transfer or the like. By doing so, an appropriate image is reproduced on the paper.

  Further, in this image forming apparatus, fine toner powder is used as a colorant, and in order to stably fix the toner arranged in an image pattern on the paper, a heating method is used for simplicity and the like. Widely used.

  Conventionally, an electrothermal roller type fixing device has been widely used as a fixing device as a heating device. However, such a fixing device takes a long time to start operation and consumes a relatively large amount of power. Inconvenience occurred.

  That is, in this fixing device, a halogen lamp is disposed inside a metal roller, and the halogen lamp is heated to heat the entire metal roller, so that the entire metal roller has a uniform temperature. Since it takes time to become operable, the time required for start-up of the operation is slow, and since the entire metal roller having a relatively large heat capacity is always heated, power consumption is also increased.

  Therefore, a heating resistor pattern is directly formed on a ceramic substrate with excellent heat resistance and durability to form a heating body, which is used as a heat source and through a thin heat resistant film. A configuration method of a fixing device that uniformly heats a material to be heated by bringing it into contact with the material to be heated such as paper has been proposed and disclosed in Patent Document 1. Further, a tension-free film in which a film as disclosed in Patent Document 2 is loosely separated from a film guide and the film is driven by the pressure roller by driving a pressure roller as a pressure unit. There are types, but this method is often adopted because the number of parts is small.

According to such a configuration method, since the heat capacity of the substrate and the film itself is small, it is possible to shorten the time required for starting up the temperature up to a predetermined temperature and to reduce power consumption.
JP-A-63-313182 JP-A-4-44075

  In recent years, copying machines and printers using an electrophotographic method have greatly increased the number of printable sheets per unit time, and as a result, the speed of image forming apparatuses has been increased. When the speed is increased, the time required for the recording material to pass through the fixing device is increased. Therefore, when the developer is fixed on the recording material as before, the speed is increased. It is necessary to give more heat and pressure than the above structure. Further, it is necessary to widen the fixing area by widening the nip portion for nipping and conveying the recording material.

  By the way, the fixing nip portion is determined by the pressing force and the pressure roller hardness, and a uniform fixing property can be ensured by the uniform nip width and the pressing force. However, in a pressure roller with a rubber or sponge rubber base layer, the nip width cannot be kept uniform due to variations in the circumferential direction or longitudinal direction of the hardness of the base layer in one roller, and the applied pressure is uniform. The case where it cannot be kept will occur. In that case, uneven fixing in the same image may occur.

  In recent years, with the development of personal computers, it has become possible to process high-definition images. Along with this, copying machines and printers as output devices are required to have higher-definition and high-quality images, and the uniformity of fixing properties within a page has become very important.

  Next, in color electrophotographic copying machines and printers that have become quite popular in recent years, glossiness (hereinafter referred to as gloss) is one of the image quality parameters for color images output by printers. There is a thing which attaches importance to, and gloss up is an issue. There is a technique for changing the material of the developer as an element for increasing the gloss. However, in order to increase the gloss level only with the developer, the melting point of the developer must be lowered, so that high temperature offset becomes a problem. Therefore, it is necessary to efficiently fix the developer on the conveying material and increase the gloss, in addition to applying much heat not only in the developer but also in the fixing device.

  Accordingly, an object of the first to third inventions according to the present invention is to provide a separate pressure means in the fixing nip portion to ensure uniform pressure and nip width, and ensure uniform fixability even within the page. Furthermore, another object is to provide a heat fixing device capable of increasing the glossiness.

  A fourth object of the present invention is to provide a pressure unit separately in the fixing nip portion to ensure uniform pressure and nip width and to have a hollow structure so that the pressure unit also has heat insulation. Accordingly, it is an object of the present invention to provide a heat-fixing device capable of efficiently applying pressure without escaping heat and ensuring uniform fixing property even within a page and further increasing glossiness.

  The purpose of the fifth and sixth inventions according to the present invention is to ensure a uniform pressure and nip width by integrating a pressure means provided separately in the fixing nip portion with the heating body, and within the page. To provide a heat fixing device capable of ensuring uniform fixing properties, increasing glossiness, further simplifying the configuration, reducing the number of parts, and reducing costs. It is.

  An object of a seventh invention according to the present invention is to provide an image forming apparatus equipped with the heat fixing device described in the first to sixth inventions.

  The above object is achieved by the heat fixing apparatus and the image forming apparatus according to the present invention described below.

  According to a first aspect of the present invention, a member to be heated is pressed against a heating body provided with a heat resistant film and an electrical resistance heating element for controlling energization of a heat generation operating temperature via the heat resistant film, and a nip portion In a heating and fixing apparatus that is nipped and conveyed by a pressure roller arranged so as to form a heat and heats the heated member by heat from a heating body via the film, the heated member in the nip portion is downstream in the conveyance direction. A heating and fixing device is provided with a means for separately applying pressure.

  According to a second aspect of the present invention, in the first aspect, the means for separately applying pressure to the heated member conveying direction downstream side in the nip portion is a separate member from the heating body. This is a heat fixing device.

  According to a third aspect of the present invention, the means for separately applying pressure to the heated member conveyance direction downstream side in the nip portion is a separate member from the heating body, and the separate member is an elastic body. A heat fixing device according to a second aspect of the present invention.

  According to a fourth aspect of the present invention, the means for separately applying pressure to the heated member conveyance direction downstream side in the nip portion is a separate member from the heating body, and the separate member is an elastic body and has a hollow structure. The heat fixing apparatus according to the second invention, wherein

  According to a fifth aspect of the present invention, in the first aspect, the means for separately applying pressure to the heated member conveyance direction downstream side in the nip portion is integrated with the heating body. This is a heat fixing device.

  According to a sixth aspect of the present invention, the means for separately applying pressure to the heated member conveyance direction downstream side in the nip portion is integrated with the heating body, and the portion to which the pressure is applied is an elastic body. According to a fourth aspect of the present invention, there is provided the heat fixing device.

  According to a seventh aspect of the present invention, there is provided an image forming apparatus comprising the heat fixing device according to any one of the first to sixth aspects.

As described above, according to the present invention, by separately providing a pressurizing means in the fixing nip portion, uniform pressure and nip width are ensured, and uniform fixability is ensured even in the page. Can increase the glossiness.
In addition, the pressure means provided separately in the fixing nip part is integrated with the heating element to ensure uniform pressure and nip width, to ensure uniform fixability in the page, and to increase the glossiness. Further, the configuration can be simplified, and the number of parts can be reduced and the cost can be reduced.

(Example 1)
Example 1 will be described below.

  FIG. 1 is a schematic sectional view of a color image forming apparatus (laser printer or copying machine) using an electrophotographic process.

  By arranging four independent color stations having photosensitive drums, developing units, and cleaning devices for yellow, magenta, cyan, and black, respectively, in a vertical row, and transporting the paper adsorbed to the ETB to perform transfer It is configured to obtain a full color image.

  Reference numerals 11 to 14 denote rotating drum type electrophotographic photosensitive members (hereinafter referred to as photosensitive drums) which are repeatedly used as image carriers, and have a predetermined peripheral speed v1 [mm / s] (process) in the counterclockwise direction indicated by an arrow. Rotation drive with speed).

  The photosensitive drum is a negatively charged OPC photosensitive member having a diameter of 30 mm, and the process speed of the image forming apparatus of this embodiment is 140 mm / sec.

  The photosensitive drum is uniformly charged to a predetermined polarity / potential by the primary charging rollers 21 to 24 during the rotation process, and then constituted by image exposure means 31 to 34 (laser diode, polygon scanner, lens group, etc.). The electrostatic latent image corresponding to each color component image (yellow, magenta, cyan, black component image) of the target color image is formed.

The charging device is a DC contact charging method in which a roller having an actual resistance of 1 × 10 ⁶ Ω to which a DC voltage of −1.2 kV is applied is driven and brought into contact with the photosensitive drum at a total pressure of 9.8 N, and charging is performed. The surface is charged to -600V. The image exposure means used in this embodiment is a polygon scanner using a laser diode, and forms an electrostatic latent image by forming an image of a laser beam modulated by an image signal on a photosensitive drum.

  Laser exposure is written in the main scanning direction (perpendicular to the paper travel) from the position signal in the polygon scanner called BD for each scanning line, and the sub-scanning direction (paper travel direction) is a switch in the paper transport path. Each color station can always perform exposure at the same position on the paper by performing a predetermined time delay from the TOP signal starting from.

  Next, the electrostatic latent image is developed by the developing unit of each station. Each of the developing devices 41 to 44 (yellow, magenta, cyan, black) is rotated in the direction of the arrow in the drawing by a rotation driving device (not shown) so that each developing device faces the photosensitive drum in the developing process. It is arranged.

  Each toner of yellow, magenta, cyan, and black is a so-called non-mag toner that does not contain a magnetic material, and is developed by a one-component contact development method.

  The developing devices 41 to 44 coat the toner with a developing blade on the developing sleeve facing the photoconductor, and develop the image by applying about −500 V to the developing sleeve that is driven to rotate at the same speed as the photoconductor. Do. The ETB 8 is driven by a driving roller 102 and is driven to rotate at a peripheral speed in the direction indicated by an arrow v2 [mm / s]. The ETB8 is a single-layer resin belt made of polyimide or polyamide having a thickness of 60 to 150 μm, PET, PBT, PEEK, PVDF, ETFE, etc., and is configured to regulate the meandering and shifting of the belt by ribs bonded to both sides of the back surface. ing. The volume low efficiency of ETB8 will be described in detail separately.

As the transfer member, there are used transfer rollers 51 to 54 of epichlorohydrin rubber adjusted to a volume resistivity of 1 × 10 ⁷ Ωcm and applied to the nip portion of the OPC from the back surface of the ETB with a total pressure of 2.94 N. Touching.

  The sheet fed from the sheet cassette contacts the transfer belt through the transfer inlet guide after passing through the registration roller.

  A suction roller 7 to which a bias is applied is provided in the vicinity of the contact point between the paper and the ETB, and a suction conveyance force is generated by applying a voltage of +1 KV and applying a charge to the paper during image formation.

The suction roller 7 is a solid rubber roller having a diameter of 12 mm in which carbon black is dispersed for resistance adjustment in EPDM rubber, and is configured to be able to apply a high-pressure bias for suction to the core metal. The resistance value of the suction roller is adjusted to 1 × 10 ⁶ Ω when a metal foil having a width of 1 cm is wound around the outer periphery of the roller and a voltage of 500 V is applied between the core and the metal core.

  Paper that is fed from a paper feed cassette (not shown), passes through a transfer inlet guide and a suction roller, and obtains a suction force with the transfer belt enters the first color transfer station. The transfer unit transfers the toner image from the first color photosensitive drum by a transfer roller provided on the back of the ETB. The bias applied to the transfer roller is calculated from the impedance of the transfer belt and paper calculated from the current flowing through the suction roller while the paper is being passed. A DC bias of about +1.5 kV is high for each station in single-sided printing in a normal environment. Applied from the power supply.

  Thereafter, each time passing through each color station, a different color toner image is transferred from the photosensitive drum to form a full color image.

  After the transfer of all colors is completed, the paper separated by the curvature from the rear end of the ETB is fixed by the fixing device 9 and discharged to the outside through the transport unit to obtain a final print.

  FIG. 2 is a schematic cross-sectional view of a tension fixing film heating type heat fixing apparatus of the present embodiment.

  Reference numeral 1 denotes a resin laterally long stay which serves as an inner surface guide member of the film 2 described later.

  Reference numeral 2 denotes an endless heat-resistant film, and a stay 1 including a heating body 3 is circumscribed. The inner peripheral length of the endless heat-resistant film 2 and the outer peripheral length of the stay 1 including the heating body 3 are larger than the film 2 by, for example, about 3 mm. Therefore, the film 2 is larger than the stay 1 including the heating body 3. The circumference is circumscribing loosely.

  In order to reduce the heat capacity and improve the quick start property, the film 2 has a total thickness of about 100 μm or less and has PTFE, PFA, FEP having heat resistance, releasability, strength, durability, etc. Or a full-layer film in which PTFE, PFA, FEP or the like is coated on the outer peripheral surface of polyimide, polyamideimide, PEEK, PES, PPS or the like. In this example, the heat resistant film 2 was coated with a polyimide film of 50 μm, PTFE of 10 μm, and a layer thickness of 60 μm.

  The inner peripheral surface side of the film 2 is coated with grease in order to improve slidability.

  Reference numeral 3 denotes a heating element, and an electric resistance material such as Ag / Pd (silver palladium) as a heating element is screen-printed to a thickness of about 10 μm and a width of 1 to 3 mm along a substantially central portion of a substrate made of alumina or the like. Are coated with glass, fluororesin or the like as a protective layer. A heating body thermistor is provided on the opposite surface of the heating body to the fixing film, and the temperature of the heating body 3 is controlled by the temperature detected by the thermistor. In this example, an alumina substrate having a width of 7 mm, a length of 270 mm, and a thickness of 1 mm was used.

  The pressure roller 6 is formed by coating a silicon foam having a length of 240 mm and a thickness of 3 mm as a heat-resistant elastic layer on an aluminum core having an outer diameter of 13 mm connected to a driving device. A fixing nip portion is formed with the film sandwiched between and a rotating body that drives the film, and is connected to the driving device by a core metal such as iron, stainless steel, or aluminum. The pressure roller 6 is rotated by transmitting a driving force from a driving motor of a driving device.

  The recording material P as a heated body is conveyed and passed through a fixing nip N formed with a film sandwiched between the pressure roller 6 and the heating body 3 to heat and press the toner image T, thereby recording the recording material P. P is fixed on P. In this embodiment, pressurization is performed with a pressure of 13 kgf.

  Next, the configuration of the fixing nip portion according to the present invention will be described in detail.

  Reference numeral 201 denotes a pressure applying member provided on the downstream side of the fixing nip portion N. The pressing member 201 is made of an elastomer such as silicone rubber and has an elastic hollow structure. Air is sealed in the hollow portion. When printing is turned on, the fixing device is activated and energization of the heating element is started, the heating element generates heat, and at the same time, the pressing member 201 starts to expand, and is higher than the height of the pressure roller side surface of the heating element. Become. In this case, the pressure application member portion on the downstream side of the nip portion N can apply a higher pressure than the other nip portions. In this embodiment, the pressure at the pressure application portion is 22 kgf when the heating body reaches the temperature control of the print and expands. As a result, even if there is a slight hardness unevenness of the pressure roller, it is possible to reliably apply pressure within the fixing nip and to ensure a nip width. With the above configuration, it is possible to obtain a good and high quality image without occurrence of fixing unevenness in the page.

  In addition, when the above configuration is used, it is possible to fix the developer on the conveying material by applying pressure after the toner is sufficiently melted and melted in the fixing device nip portion N. Gloss up is also possible.

  Fixability and gloss were confirmed using the above-described configuration.

  The main body of the image forming apparatus of this embodiment is an image forming apparatus main body having a process speed of 140 mm / s and a throughput of 25 ppm. In order to secure the fixing performance, the Asker C hardness of the pressure roller is kept low for the purpose of securing the nip width. The hardness of the silicone rubber foam 6a of the pressure roller 6 is measured at a total of 8 points, 10 mm from both ends in the longitudinal direction and 4 points in the circumferential direction. The average is considerably low at 42 °, and the nip width N = 9 mm. It is said.

  Silicone rubber foam is very difficult to manufacture with exactly the same hardness in one, and hardness variations of about 1 ° to 2 ° often occur even within the same pressure roller. . Also in this embodiment, the pressure roller has a circumferential hardness difference, and one of the four circumferential directions has a width of 3 mm in the circumferential direction of 40 °.

  As a comparative example, a fixing unit having no downstream nip pressure applying means was used. The same pressure roller as in the example was used. The paper used is Xerox 75g paper, and the image pattern is a photographic image that covers one side of the page. The image is compared when the image is rubbed with Silbon C three times by hand. Gross measured the output image using a Nippon Denshoku gloss meter.

表１は本実施例で確認した定着性とグロスの結果である。

Table 1 shows the fixability and gloss results confirmed in this example.

  Regarding the gloss, 10% or less is the x level, 10% to 13% is the △ level, and 13% or more is the ◯ level.

  In Comparative Example 1, it was confirmed that image fixability (weak fixability) was observed in part of the pressure roller cycle. This is because, in the portion where the hardness of the pressure roller is low, the fixing property is slightly lowered because the pressure is reduced only in that portion.

  In Example 1, good fixability was obtained. This is because the same pressure as that of the other portions is applied even to the portion of 3 mm in the circumferential direction where the hardness is lowered by the pressure application means in the downstream portion in the nip, so that a uniform fixing property can be obtained within the page.

  Next, the gloss will be described. The gloss judgment level is 10% or less for the x level, 10% to 13% for the Δ level, and 13% or more for the ◯ level.

  In Comparative Example 1, the gloss is 8%, which is x level. This is because a sufficient pressure is applied after the developer is heated, and it is difficult to fix the developer on the paper with the pressure after completely dissolving the developer.

  In Example 1, the gloss is 18%, which is a ◯ level. This is because a sufficient pressure is applied after the developer is heated, so that the developer can be fixed on the paper with the pressure after completely dissolving the developer.

  Thus, by providing a pressure applying means downstream of the fixing nip portion and applying a pressure higher than the surface of the heating body in the nip portion, even if there is uneven hardness in the circumferential direction of the pressure roller, a uniform pressure in the circumferential direction exists. It becomes possible to ensure a uniform fixing property within the page. Further, since it is possible to fix the developer on the transporting material with pressure after the developer is completely dissolved, it is possible to increase the gloss. Therefore, it is possible to provide an image forming apparatus that can output a high-quality image.

  In this embodiment, the material of the nip portion downstream side pressure applying means is an elastomer such as silicone rubber, but is not limited to this as long as the same effect can be obtained. Further, although the structure of the nip portion downstream side pressure applying means is a hollow structure, it is not limited to this as long as it can expand and apply pressure in the same manner. Furthermore, although the pressure of the downstream pressure applying means is 22 kgf, the same effect can be obtained, and the present invention is not limited to this.

(Example 2)
A second embodiment of the present invention will be described below with reference to FIG.

  The feature of the present embodiment is that in the first embodiment, the pressure applying means on the downstream side in the nip portion is integrated with the heating body, and the rest is the same as in the first embodiment, so the overall configuration The description and the configuration diagram are omitted.

  3 is a heating body integrated with the downstream pressure applying means. The substrate of the heating body is elastic, and a member that can be processed and functions as the heating body is used. In this example, SUS was used.

  The pressure application means on the downstream side of the nip is integrated with the heating element, but has a configuration that protrudes from the surface of the heating element toward the pressure roller, and this configuration allows pressure to be applied. is there. In this embodiment, the pressure at the pressure application portion is 22 kgf. Further, in the configuration as in the present embodiment, the nip portion downstream side pressure applying means is integrated with the heating body, so that the number of parts can be reduced and further the cost can be reduced.

  Fixability was confirmed using the above configuration.

  The main body of the image forming apparatus of this embodiment is an image forming apparatus main body having a process speed of 140 mm / s and a throughput of 25 ppm. In order to secure the fixing performance, the Asker C hardness of the pressure roller is kept low for the purpose of securing the nip width. The hardness of the silicone rubber foam 6a of the pressure roller 6 is measured at a total of 8 points, 10 mm from both ends in the longitudinal direction and 4 points in the circumferential direction. The average is considerably low at 42 °, and the nip width N = 9 mm. It is said.

  Silicone rubber foam is very difficult to manufacture with exactly the same hardness in one, and hardness variations of about 1 ° to 2 ° often occur even within the same pressure roller. . Also in this embodiment, the pressure roller has a circumferential hardness difference, and one of the four circumferential directions has a width of 3 mm in the circumferential direction of 40 °.

  As a comparative example, the configuration used in Example 1 was used as it was. The same pressure roller as in the example was used. The paper used is Xerox 75g paper, and the image pattern is a black-and-white photographic image that covers one side of the page. The image is compared when the image is rubbed with Silbon C three times by hand. Gross measured the output image using a Nippon Denshoku gloss meter.

表２は本実施例で確認した定着性とグロスの結果である。

Table 2 shows the fixability and gloss results confirmed in this example.

  Regarding the gloss, 10% or less is the x level, 10% to 13% is the △ level, and 13% or more is the ◯ level.

  In Comparative Example 1, it was confirmed that image fixability (weak fixability) was observed in part of the pressure roller cycle. This is because, in the portion where the hardness of the pressure roller is low, the fixing property is slightly lowered because the pressure is reduced only in that portion.

  In Example 2, good fixability was obtained. This is because the same pressure as that of the other portions is applied even to the portion of 3 mm in the circumferential direction where the hardness is lowered by the pressure application means in the downstream portion in the nip, so that a uniform fixing property can be obtained within the page.

  Next, the gloss will be described. The gloss judgment level is 10% or less for the x level, 10% to 13% for the Δ level, and 13% or more for the ◯ level.

  In Comparative Example 1, the gloss is 8%, which is x level. This is because a sufficient pressure is applied after the developer is heated, and it is difficult to fix the developer on the paper with the pressure after completely dissolving the developer.

  In Example 2, the gloss is 18%, which is a ◯ level. This is because a sufficient pressure is applied after the developer is heated, so that the developer can be fixed on the paper with the pressure after completely dissolving the developer.

  Thus, by providing a pressure applying means downstream of the fixing nip portion and applying a pressure higher than the surface of the heating body in the nip portion, even if there is uneven hardness in the circumferential direction of the pressure roller, a uniform pressure in the circumferential direction exists. It becomes possible to ensure a uniform fixing property within the page. Further, since it is possible to fix the developer on the transporting material with pressure after the developer is completely dissolved, it is possible to increase the gloss. Therefore, it is possible to provide an image forming apparatus that can output a high-quality image. Also, by integrating the pressure applying means with the heating body, the number of parts can be reduced, and further the cost can be reduced.

  In this embodiment, the material of the heating element is SUS, but the material is not limited to this as long as the same effect can be obtained. Further, although the structure of the nip portion downstream side pressure applying means is a hollow structure, it is not limited to this as long as it can expand and apply pressure in the same manner. Furthermore, although the pressure of the downstream pressure applying means is 22 kgf, the same effect can be obtained, and the present invention is not limited to this.

1 is a schematic sectional view of an image forming apparatus according to the present invention. 1 is a schematic cross-sectional view of a heat fixing device according to the present invention. 1 is a schematic cross-sectional view of a heat fixing device according to the present invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Horizontal stay 2 Heat resistant film 3 Heating body 6 Pressure roller 11-14 Photoconductor drum 21-24 Primary charging roller,
31-34 Image exposure means 41-44 Developer 51-54 Transfer roller 201 Fixing nip downstream side pressure application member

Claims (7)

  Pressurization arranged to form a nip by pressing a heated member with a heating element provided with a heat resistance film and an electric resistance heating element for controlling the heating operation temperature through the heat resistance film. In the heating and fixing apparatus that is nipped and conveyed by a roller and heats the heated member by heat from a heating body via the film, a means for separately applying pressure to the heated member conveying direction downstream in the nip portion is provided. A heat-fixing device characterized.   2. The heat fixing apparatus according to claim 1, wherein means for separately applying pressure to the heated member conveyance direction downstream side in the nip portion is a member separate from the heating body.   3. The heating according to claim 2, wherein the means for separately applying pressure to the heated member conveying direction downstream side in the nip portion is a separate member from the heating body, and the separate member is an elastic body. Fixing device.   The means for separately applying pressure to the heated member conveyance direction downstream side in the nip portion is a separate member from the heating body, and the separate member is an elastic body and has a hollow structure. Item 3. The heat fixing apparatus according to Item 2.   The heat fixing apparatus according to claim 1, wherein means for separately applying pressure to the heated member conveyance direction downstream side in the nip portion is integrated with a heating body.   The means for separately applying pressure to the heated member conveyance direction downstream side in the nip portion is integrated with a heating body, and the portion to which the pressure is applied is an elastic body. The heat fixing apparatus as described.   An image forming apparatus comprising the heat fixing device according to claim 1.

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