JP2010054821A - Image heating apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To prevent the problem that a film inner surface is cut and a crack which results in causing a starting point of film breakage is generated because sand or dust accumulated on film end surfaces is intruded into the case that a heat fixing apparatus of a film heating method is used in an emerging market etc., with much dust and sand. <P>SOLUTION: A step is formed slightly inward from a longitudinal end of the film on a contact surface with the film in a ceramic heater. The step is formed of protective glass for a heating body in the case of front surface heating, and the step is formed of such as a sliding layer formed on the front surface in the case of backside heating. The dust or sand is prevented from being further intruded therein and the inner surface of the film is prevented from being cut since the dust or sand is caught and stayed in gaps between the step and the film even if the dust or sand is intruded from the end of the film. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to an image heating apparatus that heats an image formed on a recording material, and more particularly to an image heating apparatus that is effective when used as a heat fixing apparatus mounted on a copying machine, a printer, or the like.

  2. Description of the Related Art Conventionally, in a heat fixing device (hereinafter referred to as a fixing device) provided in an image forming apparatus employing an electrophotographic method, an electrostatic recording method, etc., recording materials carrying unfixed toner images are pressed against each other. 2. Description of the Related Art A so-called heat roller type fixing device is widely used in which a nip portion formed by a rotating fixing roller and a pressure roller is passed to fix a recording material as a permanent image.

  On the other hand, a film heating type fixing device has been put into practical use in which power is not supplied to the fixing device during standby and power consumption is kept as low as possible. A film heating type fixing device has been proposed and put to practical use, for example, in JP-A-63-313182, JP-A-2-157878, JP-A-4-44075, and JP-A-4-204980. .

  FIG. 10A is a schematic configuration diagram showing a typical film heating type fixing device. A fixing nip portion N is formed by sandwiching a resinous or metallic high thermal conductive film 53 (hereinafter referred to as a fixing film) between the ceramic heater 51 held by the heat insulating holder 52 and the pressure roller 50. A recording material on which an unfixed toner image is formed and supported is introduced into the fixing nip portion N to perform heat fixing. As a means for forming a sufficient fixing nip width N for obtaining a good fixed image, a fixing member including a heater 51 and a fixing film 53 is pressed against a pressing roller 50 by a pressing spring (not shown) or the like. It is pressed against the elasticity of the roller 50. In addition, in order to stably form a fixing nip width N having a substantially uniform width in the longitudinal direction of the fixing member, the length of the heat insulating holder 52 is interposed through a metal stay 54 formed in an inverted U shape. A substantially uniform pressure is applied in the direction.

  A typical heater 51 used in such a film heating type fixing device is shown in FIG. For example, as proposed in Japanese Patent Application Laid-Open No. 6-5356, these heaters are obtained by forming a current-generating heating resistance layer 51b on one surface of a highly insulating substrate 51a having a flat and long shape such as alumina or aluminum nitride. The heating resistance layer is protected by a glass film 51c. The fixing film rotates in contact with the protective glass film so as to slide. Alternatively, a glass film having good slidability is formed on the other surface of the ceramic substrate, and the sliding glass film and the fixing film are slid. Therefore, the heat of the resistance heating element is transmitted to the fixing film through the glass film coated over the entire length of the heater.

Various image forming apparatuses such as printers and copiers using such a film heating type fixing device eliminate the need for preheating during standby and shorten the wait time due to high heating efficiency and rising speed. There are many advantages over the conventional method of heat fixing using a heat roller or the like.
JP 63-313182 A Japanese Unexamined Patent Publication No. 2-157878 JP-A-4-44075 Japanese Unexamined Patent Publication No. 4-204980 JP-A-6-5356

  However, the configuration of the film heat fixing apparatus as described above has the following problems.

  OA devices such as recent printers and copiers are in high demand not only in corporate offices but also in SOHO and general households, and it can be said that they have become widespread worldwide regardless of regional or economic disparity. Especially in emerging markets, such as China and India, where rapid economic development has occurred in recent years, the increase in demand for popular products is significant. On the other hand, however, the environment and infrastructure are not sufficiently developed in these emerging markets, and the problems caused by the environmental differences with developed countries are increasing year by year.

  For example, when the user's usage environment is poor, dust such as dust and fine sand is more than the general office environment. In precision devices such as printers and copiers, there are not a few problems caused by dust that enters and accumulates inside the main body due to static electricity or the like that occurs during operation of the product.

  In the case of the film heat fixing device as described above, each member is easily charged with static electricity due to the sliding of the fixing film and the pressure roller, and a large amount of dust is accumulated around the heat fixing device by being attracted to them. . Further, since the heat fixing device is the final step in the image forming process, it is installed near the paper discharge port of the image forming device. Further, in order to efficiently discharge the atmosphere heated in the apparatus by heating to the outside of the apparatus, an exhaust port or the like is often arranged around the periphery. Therefore, in an environment where dust and sand are constantly flying in a room where a fan or a fan is operating, it easily adheres to the periphery of the fixing device. On the other hand, in film heat fixing, a lubricant such as heat resistant grease is often interposed between the film and the heater in order to improve the sliding rotation of the fixing film. When the heater is heated and becomes in an operating state, the grease decreases in viscosity and is well lubricated with the heater. However, since fluidity increases, grease often flows out from the end of the film in the longitudinal direction, and the end surface of the film and the end surface of the pressure roller are often soiled. The aforementioned sand and dust that enter the inside of the main body are likely to adhere to such leaked grease, and once attached, the material remains attached to the periphery semipermanently. Among these adhering dusts, some that exist in the vicinity of the end of the film are also sunk into the inner surface of the film, and are retained between the heater and the heat insulating holder. In particular, the dust staying in the fixing nip on the inner surface of the film may move in the direction of the longitudinal center and stay in a place where something is triggered. Since the accumulated dust continues to rub against the inner surface of the film with high pressure, the inner surface of the fixing film molded with resin or the like is easily damaged in the circumferential direction. Such circumferential scratches become thermal resistance when transferring heat from the heater to the film, causing vertical streaks in the image after heat-fixing, and increasing the number of rotations of the film. It may be a factor that causes cracks. Once the cracked fixing film receives a force in the rotational direction, it proceeds to tear or tear instantaneously, and in this case, it becomes impossible to heat-fix the recording material.

  SUMMARY OF THE INVENTION An object of the present invention is to provide an image heating apparatus that does not cause image defects or damage to a fixing film even when the image forming apparatus is used in an environment with a lot of dust and sand.

In order to achieve the above object, an image heating apparatus according to the present invention heats a recording material by introducing it through a nip formed between a heating member and a pressure member that are pressed against each other. In the image heating device,
The heating member comprises a plate-shaped heater and a heat-resistant film having a low heat capacity that is sandwiched between the heater and the pressure member and moves at the same speed as the pressure member while sliding with the heater.
On the surface of the heater in contact with the film, a step parallel to the moving direction of the film is provided at a position inside the longitudinal end of the film.

  With the configuration described above, even if the image heating device is used in an environment where there is a lot of dust and sand, the dust and sand that enter the inside from the end of the film are formed in the gap formed by the step provided between the heater and the film. It can be retained and prevents further sand and dust from entering the interior. Moreover, since it is possible to prevent the inner surface of the film from being scraped by sand or dust, it is possible to prevent problems such as image defects of image vertical stripes and film damage caused by the scraping.

  Next, details of the present invention will be described in accordance with the description of the embodiments.

(1) Example of Image Forming Apparatus FIG. 1 is a schematic configuration diagram of an image forming apparatus in this embodiment.

  Reference numeral 1 denotes a photosensitive drum, in which a photosensitive material such as OPC, amorphous Se, or amorphous Si is formed on a cylindrical substrate such as aluminum or nickel. The photosensitive drum 1 is rotationally driven in the direction of an arrow, and first, the surface thereof is uniformly charged by a charging roller 2 as a charging device. Next, the laser scanner 3 performs scanning exposure with a laser beam L that is ON / OFF controlled in accordance with image information, thereby forming an electrostatic latent image. This electrostatic latent image is developed and visualized by the developing device 4. As a development method, a jumping development method, a two-component development method, a FEED development method, or the like is used, and image exposure and reversal development are often used in combination.

  The visualized toner image is transferred from the photosensitive drum 1 onto the recording material P conveyed at a predetermined timing by a transfer roller 5 as a transfer device. Here, the leading edge of the recording material is detected by eight sensors so that the image forming position of the toner image on the photosensitive drum 1 matches the writing position of the leading edge of the recording material, and the timing is adjusted. The recording material P conveyed at a predetermined timing is nipped and conveyed between the photosensitive drum 1 and the transfer roller 5 with a constant pressure. The recording material P onto which the toner image has been transferred is conveyed to the fixing device 6 and fixed as a permanent image. On the other hand, the residual toner remaining on the photosensitive drum 1 is removed from the surface of the photosensitive drum 1 by the cleaning device 7. Reference numeral 9 denotes a paper discharge sensor provided in the heat fixing device 6, and is a sensor for detecting when a paper jam occurs between the top sensor 8 and the paper discharge sensor.

(2) Heat fixing device 6
FIG. 2 is a schematic configuration diagram of the heat fixing device 6. This heat fixing device 6 is basically a film heating type heat fixing device comprising a fixing assembly 10 and a pressure roller 20 which are pressed against each other to form a nip portion N.

As shown in the cross-sectional view (a) and the perspective view (c) of FIG. 2, the fixing assembly 10 mainly includes a fixing film 13, a heater 11, a heat insulating holder 12 that holds the heater, and a pressure spring 15. And a metal stay 14 that presses the heat insulating holder 12 against the pressure roller 20.
1) Fixing film 13
The fixing film 13 is a heat-resistant film having a total thickness of 200 μm or less in order to enable quick start. The base layer is formed of a heat-resistant resin such as polyimide, polyamideimide, or PEEK, or a pure metal or alloy such as SUS, Al, Ni, Cu, or Zn having heat resistance and high thermal conductivity. In the case of a resin base layer, in order to improve thermal conductivity, high thermal conductive powder such as BN, alumina, Al, etc. may be mixed. In addition, the fixing film 13 having sufficient strength and excellent durability for constituting a long-life heat fixing device needs to have a total thickness of 20 μm or more. Therefore, the total thickness of the fixing film 13 is optimally 20 μm or more and 200 μm or less. In addition, PTFE (polytetrafluoroethylene), PFA (tetrafluoroethylene perfluoroalkyl vinyl ether copolymer), FEP (tetrafluoroethylene hexafluoropropylene copolymer) are used on the surface layer to prevent offset and ensure separation of recording materials. ), ETFE (ethylene tetrafluoroethylene copolymer), CTFE (polychlorotrifluoroethylene), PVDF (polyvinylidene fluoride) and other heat-resistant resins with good releasability such as silicone resin are mixed or used alone A release layer is formed by coating with. As a coating method, the outer surface of the fixing film 13 may be etched and then the release layer may be dipped or applied by powder spraying or the like. Alternatively, a method of covering the surface of the fixing film 13 with a resin formed in a tube shape may be used. Alternatively, after the outer surface of the fixing film 13 is blasted, a primer layer that is an adhesive may be applied to cover the release layer.
2) Heater 11
As shown in the heater cross-sectional view of FIG. 2B, the heater 11 as a heating member heats the nip portion N by contacting the inner surface of the fixing film 13. It is a plate shape with a low heat capacity, and on the surface of an insulating ceramic substrate 11a such as alumina or aluminum nitride, along the longitudinal direction, an energization heating resistor layer 11b such as Ag / Pd (silver palladium), RuO ₂ , Ta ₂ N, etc. However, it is formed by screen printing or the like with a thickness of about 10 μm and a width of about 1 to 5 mm. On the surface where the heater 11 is in contact with the fixing film 13, a protective layer 11 c is provided to protect the energized heating resistor layer within a range that does not impair the thermal efficiency. It is desirable that the thickness of the protective layer is sufficiently thin and the surface property is good. Generally, a glass coat having a thickness of about 30 μm to 200 μm is used. Details regarding the configuration in the longitudinal direction of the heater according to the present embodiment will be described later.

  The heat insulating holder 12 that holds the heater 11 is formed of a heat resistant resin such as liquid crystal polymer, phenol resin, PPS, PEEK. The lower the thermal conductivity, the better the heat conduction to the pressure roller 20, and therefore a filler such as a glass balloon or a silica balloon may be included in the resin layer. It also serves to guide the rotation of the fixing film 13.

Reference numeral 14 denotes a metal stay that contacts the heat insulating holder 12 and suppresses bending and twisting of the entire fixing assembly.
3) Pressure roller 20
The pressure roller 20 is made of an elastic solid rubber layer formed of heat-resistant rubber such as silicone rubber or fluorine rubber on the outer side of a metal core 21 made of SUS, SUM, Al or the like. An elastic sponge rubber layer or an elastic layer such as an elastic foam rubber layer in which a hollow filler (such as a microballoon) is dispersed in a silicone rubber layer and a gas portion is provided in the cured product to enhance the heat insulation effect. 22 is an elastic roller. A release layer such as perfluoroalkoxy resin (PFA) or polytetrafluoroethylene resin (PTFE) may be formed thereon.
4) Driving and Control Method of Heat Fixing Device 6 The fixing member 10 is pressed against the elasticity of the pressure roller 20 by the following configuration to form a predetermined nip N. That is, as shown in FIG. 2 (c), both ends of the metal stay 14 in the longitudinal direction protrude from the heat insulating holder 12, and the spring receiving portions 14a at both ends of the stay are moved by the coil spring 15 via the spring receiving members. Pressurized (total pressure 10.0-12.0 kg in this example). The load is transmitted uniformly over the longitudinal direction of the heat insulating holder 12 via the stay foot 14b.

  In the fixing nip portion N, the fixing film 13 is bent by being sandwiched between the heater 11 and the pressure roller 20 by the applied pressure, and is in close contact with the heating surface of the heater 11.

  The pressure roller 20 obtains a driving force that rotates in the direction of the arrow in FIG. 2A by a driving gear (not shown) provided at the end of the cored bar 21. The driving force is transmitted from a motor (not shown) according to a command from a CPU (not shown) that controls the control means.

  As the pressure roller rotates, the fixing film 13 is driven to rotate by the frictional force with the pressure roller 20. By interposing a lubricant such as a fluorine-based or silicone-based heat resistant grease between the fixing film 13 and the heater 11, the frictional resistance is kept low, and the fixing film 13 can be smoothly rotated.

  Also, the temperature control of the heater is appropriately determined by determining the duty ratio and wave number of the voltage applied by the CPU to the energization heating resistor layer according to the signal from the temperature detection element such as thermistor (not shown) provided on the back of the ceramic substrate. By controlling, the temperature in the fixing nip is maintained at a desired fixing set temperature.

The recording material P holding the unfixed toner image is appropriately supplied by a supply unit (not shown) at a predetermined timing, and is conveyed into the fixing nip to be heated and fixed. The recording material P discharged from the fixing nip is guided and discharged by a paper discharge guide (not shown).
(3) Features of the heater in the embodiment FIG. 3 shows a detailed configuration of the heater 11 representing the embodiment in the longitudinal direction. In the heater represented by the conventional example, as shown in FIG. 4, the protective glass provided on the surface of the heater is extended to the outside of the film end surface. A flat surface is formed uniformly in the direction. On the other hand, as shown in FIG. 3, the present embodiment is characterized in that a step is provided on the protective glass in a region inside from the position of the end portion of the fixing film 13 and outside the energization heating resistance layer. Such a step can be formed, for example, by a method such as screen printing or the like, in which the first layer is first applied and dried, and then the second layer is applied. Since the protective glass is originally provided for the purpose of insulating the energization heat generating resistance layer from the member in contact with the heater, it is required to be at least 30 to 50 μm although it depends on the thickness of the resistance layer and the glass material. Therefore, the second layer is applied after the first layer is applied with a thickness of 30 to 50 μm. As will be described later, it is preferable to provide a step larger than the particle size of the dust in order to prevent the dust entering the film from entering further inside. If the particle size of the dust is about 10 μm to 50 μm, the total thickness of the glass in the two-layer forming part is appropriately about 50 μm to 100 μm because the thickness corresponding to the particle size is added to the thickness of the first layer. Moreover, it is also possible to apply an imide resin such as polyimide for the purpose of changing the material of the second layer glass and improving the slidability with respect to the first layer glass.
(4) Comparison of effects 1) Comparison with conventional example In the following, as a representative configuration of this example, a step provided on the inner side of the film end of the heater glass surface, and a conventional stepped heater are used. A heat fixing device equipped with each heater was mounted on a printer, and the performance was compared based on the endurance of paper passing. In order to confirm the effect of suppressing dust intrusion due to steps, the end of the film is applied to the end with about 2 mg of the same grease as the grease applied to the heater surface and stretched. In order to create a dusty state that could occur in the market, a 50,000-sheet endurance test was conducted. In the comparative experiment in this example, the glass step on the heater surface is 50 μm. The results are shown in Table 1.

上記結果より明らかなように、ヒータガラス面に段差を設けた方が、通紙耐久に対して良好な結果であった。図５に従来例と本実施例において、通紙耐久途中のヒータ面上の状態を模式的に示す。１６はフィルム１３の長手端部方向への寄りを規制する規制フランジである。図５（a）の従来例では、ガラス面に段差が無い為に、フィルム端面から侵入した砂埃が数箇所において内部にまで進行しており、そのうちの幾つかにおいて画像上に縦スジが発生するような溝がフィルム内面に発生している。このような溝が掘られた箇所は、フィルムのベース層であるポリイミドが削れグリースや砂埃とともに大きな塊を形成し、それらが相まってさらに大きな傷を発生させる原因となる。また、耐久が経過するに従ってフィルムの亀裂や破損へと進行する。一方で図5（b）本実施例のようにフィルム端部よりも内側においてヒータ面に段差を設けることによって、保護ガラス段差部とフィルムの間に出来た空隙に砂埃が引っかかってそれ以上中に侵入することを食い止めることができる。さらに空隙部は加圧ローラとの押圧による圧力を受けにくいので、そこに溜まった砂埃で積極的にフィルム内部を削ることが無いので、フィルムへのダメージを抑制する効果もある。

As is clear from the above results, it was better to provide a step on the heater glass surface with respect to paper passing durability. FIG. 5 schematically shows a state on the heater surface in the middle of paper passing durability in the conventional example and the present embodiment. Reference numeral 16 denotes a regulating flange that regulates the shift of the film 13 in the longitudinal end portion direction. In the conventional example of FIG. 5 (a), since there is no step on the glass surface, dust that has entered from the end face of the film has progressed to the inside at several places, and vertical stripes are generated on the image in some of them. Such a groove is generated on the inner surface of the film. The location where such a groove is dug causes the polyimide, which is the base layer of the film, to be scraped off to form a large lump together with grease and dust, which together cause a larger scratch. Moreover, it progresses to the crack and damage of a film as durability passes. On the other hand, by providing a step on the heater surface inside the film end as shown in FIG. 5 (b), dust is trapped in the gap formed between the protective glass step and the film, and further inside. Can stop intrusion. Further, since the gap is not easily subjected to pressure due to pressing with the pressure roller, the inside of the film is not actively scraped by the dust accumulated therein, and there is also an effect of suppressing damage to the film.

  As explained above, by providing a step inside the film end of the heater glass surface, dust can be prevented from entering from the end of the film, and image defects and film breakage can be suppressed. It becomes possible.

  FIG. 6 shows a configuration of the heater 11 representing the second embodiment. In this embodiment, an electrode is provided on the surface (back surface) opposite to the surface on which the energized heat generating resistance layer 11b is provided, and the electrode and the energized heat generating resistance layer secure a conduction path by a through hole provided in the ceramic substrate. By adopting such a configuration, the same configuration as that of Example 1 can be achieved by using only one glass layer provided on the heating resistance layer. That is, a step formed by the ceramic substrate and the protective glass can be provided by setting the coating region in the longitudinal direction of the protective glass to the inside of the fixing film and the outside of the energization heating resistor layer. By making this level difference 30 μm to 100 μm, intrusion of dust can be suppressed. In addition, since the step can be provided with only one layer of the protective glass, the thickness of the protective glass in the energization heating resistor layer can be made thinner than that of the first embodiment, so that the thermal conductivity can be improved. It becomes. In order to actually maintain the surface temperature of the fixing film at 180 ° C., if the total thickness of the protective glass is 100 μm in the configuration of Example 1, it is necessary to set the temperature control temperature of the heater to 205 ° C. On the other hand, in the configuration of Example 2, the thickness of the protective glass is 50 μm, and the temperature adjustment temperature of the heater can be lowered to 195 ° C.

  FIG. 7 shows the configuration of the heater 11 representing the third embodiment. In this embodiment, the energization resistance heating element 11b formed on the heater is formed on the back side of the ceramic substrate (the side opposite to the nip heating surface), and the heat energy of the heating element is transmitted to the nip side through the substrate. In some cases, the same configuration as in the first and second embodiments can be achieved by the sliding layer 11d provided on the surface of the ceramic substrate. In the case of Example 1 and Example 2, since it is necessary to ensure the pressure resistance of the energization heat generating resistance layer and the protective glass, at least a material that can ensure sufficient insulation like glass and a thickness of 30 μm or more is required. However, if the heating resistance layer is on the back surface as in the present embodiment, the insulation to the nip side can be secured by the ceramic substrate, so that the intrusion of dust can be prevented by the sliding layer 11d provided on the substrate surface.

  Since the sliding layer 11d is mainly intended to improve the sliding property with the fixing film, the material is not only a glass layer, but also imide resins such as polyimide and polyamideimide, PTFE and PFA fluorine resins, Alternatively, it can be formed by a dry film made of graphite, diamond-like carbon (DLC), molybdenum disulfide, or the like. When protective glass is set on the heating surface as in Example 1 or Example 2, for example, if a thin metal sleeve such as stainless steel is used for the base layer of the fixing film, the sliding property between the glass and the metal layer This causes a problem that the inner surface of the metal sleeve is scraped. In such a case, it is desirable to form the sliding layer with the resin layer as described above. The same effect can be obtained by providing a step in the longitudinal direction of the sliding layer in the same manner as in Examples 1 and 2 up to the position inside the end face of the fixing film and outside the energization heating resistor layer. be able to. In addition, the thickness of the sliding layer can also be set thin considering thermal conductivity, but if it is too thin, if the particle size of dust entering the film is large, the effect of preventing intrusion will not work. It is necessary to set according to the particle size of the dust and sand assumed according to the environment of the user in which the apparatus is used.

  FIG. 8 shows a configuration of a heater representing the fourth embodiment. In this embodiment, as shown in FIG. 8, the substrate constituting the heater is not provided with a protective glass or sliding layer provided on the heater as in Examples 1 to 3, but a step for preventing dust from entering. A step is formed by changing the thickness of the film in the longitudinal direction. A heater substrate molded mainly of alumina or aluminum nitride forms a flat plate by extrusion molding, and obtains a plurality of longitudinal substrates by dividing the flat plate. Even when a heater substrate having a step as shown in the figure is formed, a desired substrate can be obtained by forming a flat plate having a step parallel to the extrusion direction by extrusion and then dividing the plate in a direction perpendicular to the step. be able to. As shown in the figure, when a current-carrying resistance layer, an electrode, and protective glass are sequentially laminated on a substrate having a step, the step is formed on the surface so that the glass follows the step of the heater substrate. Also by using such a heater, it is possible to suppress the intrusion of dust into the film, and the same effects as in the first to third embodiments can be obtained. In addition, when a heating resistance layer is formed on the back side of the heater, it is possible to ensure a good sliding state with the film even if it is desired to set the sliding layer on the heater surface as thin as possible, or even if the sliding layer is not particularly required. In this case, the step for preventing dust intrusion can be formed only by providing the step with the heater substrate as in this embodiment.

(Other developments of the present invention)
(1) As shown in FIG. 9, in an electromagnetic induction heating type heat fixing device, a fixing film 43 based on a metal sleeve having electromagnetic induction heat generation is heated by an exciting coil 42 and a magnetic core 44. Therefore, the plate-like heater as in the above embodiment is not provided in the nip portion. Instead, a sliding plate 41 is provided on the film inner surface side of the nip portion in order to form a nip having an appropriate width necessary for fixing. The sliding plate is molded from ceramic, glass or a resin having heat resistance and slidability, but it is also possible to provide a step on the surface of such a sliding plate at a position inside the end of the fixing film. Intrusion of dust and the like can be prevented by steps, and the effects of the present invention can be obtained.

  (2) In the present invention, as described in each drawing, the step provided on the heater surface is provided so as to be parallel to the traveling direction of the recording material. However, the form of the step is not limited to this. For example, when the level difference causes a flaw on the fixing film, the level difference can be provided obliquely with a straight line or a curve with respect to the rotation direction of the film. Further, the shape of the step is not limited to a right angle, and may be an acute angle, an obtuse angle, an R shape, or chamfered in consideration of the function and the contact state with the fixing film.

1 is a schematic sectional view showing an image forming apparatus according to the present invention. 1 is a schematic configuration diagram showing a heat fixing device according to the present invention. 1 is a schematic configuration diagram illustrating a heater according to Embodiment 1. FIG. The schematic block diagram explaining the heater which concerns on a prior art example. Schematic explaining the effect of this invention. FIG. 5 is a schematic configuration diagram illustrating a heater according to a second embodiment. FIG. 5 is a schematic configuration diagram illustrating a heater according to a third embodiment. FIG. 6 is a schematic configuration diagram illustrating a heater according to a fourth embodiment. The schematic block diagram explaining the other developed form of this invention. It is a schematic sectional drawing showing the heat fixing apparatus of the film heating system of a prior art example.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Photosensitive drum 2 Charging roller 3 Scanner 4 Developing device 5 Transfer roller 6 Heating and fixing device 7 Cleaning device 8 Top sensor 9 Paper discharge sensor 10 Fixing assembly 11 Heating heater 11a Heater substrate 11b Electric heating resistance layer 11c Protective glass 11d Sliding layer 12 Heat insulation holder 13 Fixing film 14 Metal stay 15 Pressure spring 16 End regulating flange 20 Pressure roller 21 Core metal 22 Elastic layer 41 Sliding plate 42 Excitation coil 43 Fixing film 44 Magnetic core 50 Pressure roller 51 Ceramic heater 52 Heat insulation holder 53 Fixing film 54 Metal stay P Recording material L Laser light

Claims (8)

In an image heating apparatus that performs heating by introducing and passing a recording material through a nip formed between a heating member and a pressure member that are pressed against each other,
The heating member comprises a plate-shaped heater and a heat-resistant film having a low heat capacity that is sandwiched between the heater and the pressure member and moves at the same speed as the pressure member while sliding with the heater.
An image heating apparatus, wherein a step is provided on the surface of the heater in contact with the film at a position inside the longitudinal end of the film. The heater is a heater having a good thermal conductivity substrate, an energization heating resistance layer provided on the first surface on the good thermal conductivity substrate, and a glass coat layer as a protective layer for the energization heating resistance layer. ,
2. The image heating apparatus according to claim 1, wherein the step is a step formed by the glass coat layer. The heater is a heater having a good thermal conductivity substrate, an energization heating resistance layer provided on the first surface on the good thermal conductivity substrate, and a glass coat layer as a protective layer for the energization heating resistance layer. ,
2. The image heating apparatus according to claim 1, wherein the step is a step formed by a sliding layer and a good heat conductive substrate formed on the second surface of the good heat conductive substrate. The heater includes a highly heat conductive substrate, an energization heating resistor layer provided on the first surface of the good heat conductivity substrate, a glass coat layer provided as a protective layer for the energization heating resistor layer, An electrode for energizing the heat generating resistance layer is provided on the second surface of the good heat conductive substrate, and the electrode and the current generating heat resistance layer are heaters having a conduction path by a through hole provided in the good heat conductive substrate. ,
2. The image heating apparatus according to claim 1, wherein the step is a step formed by the glass coat layer and a highly heat conductive substrate. The heater is a heater having a good thermal conductivity substrate, an energization heating resistance layer provided on the first surface on the good thermal conductivity substrate, and a glass coat layer as a protective layer for the energization heating resistance layer. ,
2. The image heating apparatus according to claim 1, wherein the step is formed by a step provided in advance on a good heat conductive substrate.   The image heating apparatus according to claim 2, wherein the heat-conductive substrate is made of ceramic.   The image according to any one of claims 2 to 6, wherein the step is formed at a position inside the longitudinal end of the film and outside the longitudinal end of the energization heating resistance layer. Heating device.   The image heating apparatus according to claim 1, wherein the step is 10 μm or more and 200 μm or less.

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