JP2010134094A - Image heating device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a means for performing satisfactory heat fixing without unnecessary wait time and without increasing the adjustment temperature of a heater, even when a heat fixing device of a film heating system is in a cold state. <P>SOLUTION: The image heating device introduces a recording material to a nip and passes it through the nip, thereby heating the material, the nip being formed in a pressure contact part between a pressure roller 20 and a fixing film 13 incorporating the heater 11. In the image heater, 3% or more air holes of the surface area of a stay are lengthwise formed at substantially regular intervals in the surface of a metal stay 14, which is molded in an inverted U shape for lengthwise pressing it against a heat insulation holder 12 holding the heater. By reducing the heat capacity of the stay and increasing the heat insulation effect, heat transfer efficiency during a cold period is enhanced. <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 is proposed in, for example, JP-A-63-313182, JP-A-2-157878, JP-A-4-44075, JP-A-4-204980, and JP-A-8-6409. Has been put to practical use.

FIG. 10 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, the fixing member including the heater 51 and the fixing film 53 is pressed against the pressure roller 50 by a pressure spring 55 or the like. It is pressed against the elasticity of. Further, in order to stably form a fixing nip width N having a substantially uniform width in the longitudinal direction of the fixing member, the heat insulating holder 52 that holds the heater 51 is bent by the pressurizing means, or during rotation driving. It is important not to twist. As a means for that, it is essential that the heat insulating holder 52 is pressed with a substantially uniform pressure in the longitudinal direction via a metal stay formed in an inverted U shape as shown by 54.
JP-A-63-313182 Japanese Patent Laid-Open No. 2-157878 JP-A-4-44075 JP-A-4-204980 JP-A-8-6409

  However, the above-described inverted U-shaped metal stay 54 needs to have a thickness of at least 1.0 mm in order to ensure sufficient rigidity against the applied pressure, and the thickness needs to be increased as the applied pressure is increased. There is. Since the stay 54 is a metal member such as aluminum or iron, the stay 54 has a much larger heat capacity than other resin members constituting the fixing member.

  A film heating type heat fixing apparatus does not require power supply for maintaining a predetermined standby temperature during standby because of its high heating efficiency. Therefore, when the image forming apparatus is not used for a long time, the fixing member is cooled to a temperature equivalent to room temperature (hereinafter referred to as a cold state). When printing is started in the cold state, the heat energy from the heater 51 is also absorbed by the metal stay 54 having a large heat capacity, so that the amount of heat transferred to the fixing nip side is reduced.

  In order to obtain a good fixed image even in such a state, there are means such as performing heat fixing after standby until the metal stay 54 is sufficiently warmed or setting the temperature of the heater 51 higher. However, the former case is not preferable because an unnecessary wait time is given to the user. In the latter case, there is no problem if there is a design margin for setting the temperature control temperature high, but the control temperature of the heater 51 has already reached its limit with the recent increase in the speed of printers and copiers. However, if the temperature is controlled at a higher temperature, the heat resistance temperature of the surrounding resin member may be exceeded, or the limit temperature of the current-carrying safety element such as a thermo switch or a thermal fuse may be exceeded. Moreover, it is not preferable also from a viewpoint of energy saving.

  Accordingly, an object of the present invention is to provide a means for performing good heat fixing without requiring unnecessary wait time and increasing the temperature of the heater even in a cold state of the heat fixing device. is there.

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 roller that are in pressure contact with each other. In the image heating device,
The heating member is sandwiched between a heater, a frame for holding the heater, a metal stay that pressurizes the frame, and the heater and a pressure roller, and is pressed while sliding with the heater. It is made of a heat-resistant film having a low heat capacity that moves at the same speed as the roller, and the metal stay is provided with holes of 3% or more with respect to the surface area at regular intervals in the longitudinal direction.

  As described above, according to the present invention, holes are provided at equal intervals in the longitudinal direction on the surface of the metal stay for transmitting a uniform applied pressure in the longitudinal direction of the frame holding the heater. As a result, the heat capacity of the metal stay can be reduced and the heat insulation can be improved, so that the heat of the heater can be effectively transferred in the direction of the recording material even during the heating operation in the cold state. This makes it possible to suppress image defects such as fixing defects.

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

(1) 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, and 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 to 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
2A and 2B are schematic configuration schematic diagrams of the heat fixing device 6. FIG. The heat fixing device 6 is basically a film heating type heat fixing device comprising a fixing assembly 10 and a pressure roller 20 that are in pressure contact with each other to form a nip portion N.

  In the cross-sectional view (a) of FIG. 2, the fixing assembly 10 mainly pressurizes the heat insulating holder 12 by receiving pressure from the fixing film 13, the heater 11, the heat insulating holder 12 that holds the heater, and the pressure spring 15. The metal stay 14 is pressed against the roller 20.

1) Heater 11
The heater 11 as a heating member heats the nip portion N by contacting the inner surface of the fixing film 13. It has a plate shape with a low heat capacity, and an energization heating resistance layer such as Ag / Pd (silver palladium), RuO ₂ , Ta ₂ N is formed along the longitudinal direction on the surface of an insulating ceramic substrate 11 such as alumina or aluminum nitride. The film is formed by screen printing or the like with a thickness of about 10 μm and a width of about 1 to 5 mm. A protective layer that protects the energized heating resistance layer may be provided on the surface where the heater 11 is in contact with the fixing film 13 as long as the thermal efficiency is not impaired. 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 50 μm to 70 μm is used. Alternatively, the back surface heat generation type structure may be configured such that the surface opposite to the surface provided with the energization heat generation resistance layer is in contact with the fixing film. In that case, a glass coat is directly applied on the ceramic substrate to provide slidability. Make it. Alternatively, a fluorine resin such as PTFE or PFA, or an imide resin layer such as polyimide or polyamideimide may be coated as a single layer or mixed, or a dry property made of graphite, diamond-like carbon (DLC), molybdenum disulfide or the like The film may be formed as a lubricant or a sliding material.

  The heat insulating holder 12 that holds the heater 11 is formed of a heat resistant resin such as a liquid crystal polymer, a phenol resin, PPS, or 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. Details will be described later.

2) 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 the resin base layer, in order to improve the thermal conductivity, a high thermal conductive powder such as BN, alumina, Al or the like may be mixed. Further, the fixing film 13 having a sufficient strength and excellent durability for constituting a long-life heat fixing apparatus 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. Furthermore, 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 the recording material. ), 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.

3) Pressure roller 20
The pressure roller 20 is made of an elastic solid rubber layer formed of a heat-resistant rubber such as silicone rubber or fluorine rubber on the outside 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. 2B, the metal stay 14 has both ends in the longitudinal direction protruding 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.

  At 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) in accordance with 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.

  In addition, the temperature control of the heater is appropriately determined by determining the duty ratio, wave number, etc. of the voltage applied by the CPU to the energized heating resistor layer according to the signal of a temperature detection element such as a thermistor (not shown) provided on the back of the ceramic substrate Thus, 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 metal stay in this embodiment FIG. 3 shows details of the metal stay 14 that represents this embodiment. The stay is formed by bending a hole 16 with a diameter of about 4.0 mm into a 1.6 mm-thick galvanized steel plate so that each hole is evenly spaced and bending it into an inverted U shape. It is. The arrangement method is limited to these, for example, when holes are arranged in a row on each surface of the stay as shown in FIG. 3A, or a plurality of small holes are arranged as shown in FIG. 3B. It is not a thing. The other material used for the stay may be a single metal or a composite material combined with a resin or the like that can ensure rigidity against a predetermined pressure, such as aluminum or stainless steel. Regarding the processing, depending on the material, it can be formed into a desired shape by cutting or molding.

  In order to reduce the heat capacity of the entire stay, the holes 16 should be large and have a large number. However, it is necessary to reduce the bending with respect to the applied pressure so as not to impair the rigidity. As will be described later, the ratio of the holes to the surface area of the stay (hereinafter referred to as the porosity) is preferably about 5% to 40%. As the size of the holes, the diameter is about 1.0 mm to 6.0 mm, the number is determined according to the porosity, and the distance between the holes is also set so that the strain stress in the longitudinal direction is evenly distributed. Set and arrange evenly. Moreover, it is better not to provide holes in places where stress is concentrated, such as a bent R portion of the sheet metal, or in the vicinity of the stay leg portion 14b in contact with the heat insulating holder 12.

  Table 1 shows the amount of bending of the metal stay with respect to the porosity and the maximum stress applied to the stay. Note that the pressure applied to both ends of the stay was 5.0 kg on one side and 10.0 kgf on both ends. The amount of deflection is represented by the difference between the longitudinal center portion and the end portion of the stay foot portion 14b.

  As can be seen from Table 1, as the porosity increases, both the amount of deflection at both ends and the maximum stress increase. Here, FIG. 4 shows a schematic explanatory view of the metal stay 14 and the stay receiving portion 12a of the heat insulating holder 12 as viewed from the side of the longitudinal direction. When the amount of bending of the metal stay 14 due to the pressurization increases, the heat insulating holder 12 and the heater 11 that are in contact with the stay receiving portion also follow the bending, so that the pressure applied against the pressure roller 20 depends on the longitudinal direction. It will be different. As a result, the shape of the fixing nip becomes narrow at the center as shown in the figure, and uniform heating and fixing cannot be performed in the longitudinal direction. In order to avoid such a problem, as shown in FIG. 5A, if a crown amount is provided in the longitudinal direction on the surface of the metal stay 14 that contacts the heat insulation stay in advance, Since the stay foot 14b in contact with the heat insulation stay can maintain a straight shape, a stable nip can be formed in the longitudinal direction. Alternatively, as shown in FIG. 5 (b), a fixing nip having a stable shape can be formed by providing a crown amount in the metal stay receiving portion on the heat insulating stay side and correcting the deflection of the metal stay 14. If the amount of deflection changes depending on the porosity as shown in Table 1, a crown amount corresponding to each of the amounts may be set.

  However, it can be seen that when the porosity exceeds 30%, the maximum stress increases to around 100 Mpa. This is due to the fact that the maximum stress is greatly increased at a location where the stress with respect to the load is partially concentrated, for example, at a portion where the inverted U-shaped corner portion of the metal stay is close to the hole. The metal stay made of gin-coated steel plate used in this example has a maximum shear stress of about 250 Mpa. Therefore, when a porosity of 40% or more is formed, sufficient strength against deformation of the stay due to load cannot be secured. From the above, it is considered appropriate to set the ratio of holes provided on the surface of the metal stay to 40% or less. Note that the amount of stay deflection and maximum stress vary depending on the size of the holes, the distance between each hole, the thickness of the metal stay, and the applied pressure. However, it is desirable to adjust appropriately according to the design conditions.

(4) Comparison of effects 1) Comparison of fixing performance with the conventional example In the following, a case where a hole is formed in the metal stay 14 as a representative configuration of this embodiment and a metal stay without a hole as in the conventional case are provided. When used, the fixing performance after heat fixing of unfixed toner images was compared.

As a method for comparing the fixing performance, an index called density reduction rate described below was used. FIG. 6 shows an image pattern for obtaining the density reduction rate. The recording material size, basis weight, and type were LTR size 90 g / m ² , cardboard. On the recording material, as shown in FIG. 6, nine patches are used that are evenly arranged in three rows on the top and bottom and three columns on the left and right. The size of one patch is a 1 cm × 1 cm square, and here, solid black is used as an image pattern in the patch. Depending on the evaluation, a halftone image formed with appropriate dots may be used. (Such a pattern is hereinafter referred to as a fixability evaluation pattern.)
The LTR paper on which the unfixed toner image of the fixability evaluation pattern is formed is heated and fixed, and the reflection density of each patch after fixing is measured. This reflection density is referred to as “pre-rubbing density”. (Macbeth-RD914 manufactured by Macbeth Co. was used as the reflection densitometer.) Next, each patch was rubbed a predetermined number of times using a predetermined weight. It is preferable to attach rubbing paper such as sylbon paper on the surface where the weight rubs against the image so that the surface of the image is moderately easily rubbed. In this example, a 200 gf weight was used and each patch was rubbed 10 times. The image density of each patch after rubbing is measured in the same manner as before rubbing, and this density is defined as “post-rubbing density”. The concentration reduction rate is expressed by the following equation.

(Density reduction rate) = {(Concentration before rubbing) − (Concentration after rubbing)} / (Concentration before rubbing)
× 100 (%)
The density reduction rate in each patch is calculated, and the average of 9 points is defined as “average value”, and the maximum value among the 9 points is defined as “maximum value”.

  Using the image forming apparatus, the heat fixing device printed 10 sheets continuously from the cold state, and the density reduction rate was compared. As an object of comparison, as a conventional example, a case where a metal stay without holes is used, and 2 to 6 are 5%, 10%, 20%, 30%, 40% voids relative to the surface area of the metal stay The case where a hole was provided was compared. The results are shown in the graph of FIG. FIG. 7A shows a comparison of average values. FIG. 7B is a graph comparing the maximum values.

  As is apparent from the results, it can be seen that the concentration reduction rate from the cold state to about the fifth sheet is lowered by providing the voids of 5% or more. In the seventh sheet or more, the difference in the density decrease rate indicates that the difference in the heat transfer due to the presence or absence of holes is eliminated because the metal stay is gradually warmed. In addition, when the porosity is 30% or more, the concentration reduction rate does not change so much, indicating that the heat insulation effect by the pores is saturated. Therefore, it is understood that the porosity provided in the metal stay is preferably about 5% to 40%.

2) Consideration by heat capacity Here, as a means for achieving the object of the present invention, it was confirmed that it is more effective to provide holes on the surface of the metal stay as follows. For example, consider a case where a heat capacity equivalent to the heat capacity of a metal stay having a thickness of 1.6 mm and a porosity of 20% of the surface area is achieved by reducing the thickness of the stay. In other words, when the surface of the metal stay has no holes and is adjusted by the thickness of the stay, an equivalent heat capacity can be achieved with a thickness of just 1.28 mm. For these two configurations, the fixing performance was compared as described above. The results are shown in the graph of FIG. As is apparent from the results, it can be seen that the metal stay provided with holes has better fixing performance.

  This indicates that the transmission of the heater heat energy is not simply determined by the heat capacity of the metal stay. By providing holes, it can be said that it is important that the amount of radiant heat received from the heater is small, and that the amount of received heat is further radiated to the outside of the stay, that is, the heat insulation is excellent. A thin-walled stay with only a reduced heat capacity does not have such heat insulation performance, so it can be said that the effect is small.

  As described above, in this embodiment, by providing a hole on the surface of the inverted U-shaped metal stay for transmitting a uniform pressure in the longitudinal direction of the heat insulating holder that holds the heater, Since the heat capacity can be reduced and the heat insulation can be improved, even when the heating and fixing device is in a cold state, the heat of the heater can be efficiently transmitted to the direction of the recording material. Image defects can be prevented.

FIG. 9 shows a schematic view of a heat fixing device representing the second embodiment. This embodiment is characterized in that the ratio of the holes provided on the metal stay is partially changed with respect to the longitudinal direction. More details
(1) As shown in FIG. 9A, a case where there are many holes in only a part in the longitudinal direction.

  (2) A case in which many holes are provided at predetermined intervals as shown in FIG.

(3) As shown in FIG.
Depending on the purpose, it is possible to classify how to provide holes. The operational effects for each case will be described below.

  In the case of having a large number of holes or a large hole only in a part in the longitudinal direction as in (1), a functional member or the like that absorbs heat is provided inside the metal stay at a portion that coincides with the location of the heater back or heat insulation. Suitable when installed on a holder. For example, when a safety element 17 such as a thermo switch or a thermal fuse is installed on the back surface of the heater, the temperature of the film surface in the nip is usually higher than that of the surrounding area because the member takes heat from the heater. Tend to go down. This often causes fixing defects and image unevenness, gloss unevenness, and the like. Therefore, by providing a large hole outside the place that absorbs such temperature, and suppressing the heat dissipation of that part, the temperature of the film surface can be kept uniform, so that image defects etc. occur Can be prevented.

  The effect of (2) is the same as that of (1), but for example, as shown in FIG. 9B, the heat insulating holder that holds the heater has a smooth rotation and shape when the fixing film rotates. In many cases, ribs 12a for externally fitting the film are provided in order to maintain the resistance. Since the fixing film comes into contact with the ribs 12a, heat is taken away at the contact portions, and may appear as rib marks on the image. Even for such a problem, image defects can be suppressed by providing a high porosity in that portion.

  (3) As shown in FIG. 9 (c), the longitudinal end portion of the film has an extension portion of the pressure roller and a member 18 such as a flange for guiding the running of the film. Heat flows outward. For this reason, fixing failure at both ends of the image on the recording material may occur. Even in such a case, by partially increasing the porosity at both ends of the longitudinal direction, it is possible to suppress heat dissipation at the ends and prevent fixing defects.

  As described above, in this embodiment, when there is a cause that the heat distribution is different in the longitudinal direction of the fixing device, the porosity of the metal stay surface is set high at a point where the temperature becomes low. Thus, it is possible to suppress the endothermic heat of the portion and to suppress image defects caused by temperature unevenness or the like.

1 is a schematic sectional view showing an image forming apparatus according to the present invention. The schematic block diagram showing the image heating apparatus which concerns on this invention. FIG. 3 is a schematic configuration diagram illustrating a metal stay according to the first embodiment. 1 is a schematic diagram illustrating a configuration of Embodiment 1. FIG. 1 is a schematic diagram illustrating a configuration of Embodiment 1. FIG. FIG. 3 is a schematic diagram illustrating the operational effects of the first embodiment. 6 is a graph for explaining the operational effects of the first embodiment. 6 is a graph for explaining the operational effects of the first embodiment. FIG. 6 is a schematic diagram illustrating a configuration of a second embodiment. 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 Heat fixing device 7 Cleaning device 8 Top sensor 9 Paper discharge sensor 10 Fixing assembly 11 Heating heater 12 Heat insulation holder 13 Fixing film 14 Metal stay 15 Pressure spring 16 Hole 17 Safety element 18 Flange 20 Pressure roller 50 Pressure roller 51 Ceramic heater 52 Heat insulation holder 53 Fixing film 54 Metal stay 55 Pressure spring P Recording material L Laser light

Claims (6)

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 roller that are pressed against each other,
The heating member is sandwiched between a heater, a frame for holding the heater, a metal stay that pressurizes the frame, and the heater and a pressure roller, and is pressed while sliding with the heater. It consists of a heat-resistant film with a low heat capacity that moves at the same speed as the roller.
3. An image heating apparatus according to claim 1, wherein the metal stay is provided with holes of 3% or more with respect to the surface area at regular intervals in the longitudinal direction.   The image heating apparatus according to claim 1, wherein the film is a thin cylindrical film that rotates while being guided by the frame.   The image heating apparatus according to claim 1, wherein the heater is a heater having a plate-like ceramic base.   The image heating apparatus according to any one of claims 1 to 3, wherein the metal stay is formed by bending a sheet metal provided with holes in advance into an inverted U shape.   5. The image heating apparatus according to claim 1, wherein the hole provided in the metal stay has a ratio of the hole changed with respect to a longitudinal direction of the stay.   The image heating apparatus according to claim 5, wherein the holes provided in the metal stay have a ratio of holes in both longitudinal ends of the stay greater than a ratio of holes in the central part.

Images