JP2020034940A - Image heating device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a good image by suppressing local temperature unevenness of a heater while maintaining a soaking effect of a heat conductive member. A heat conductive member 17 is provided with a region 17a1 and a region 17a2 having a heat capacity smaller than that of the region 17a1, and the heater 11 is in contact with a region 17a1 of the regions of the heater 11 for heating a nip portion. A heater region 11b1 in which the temperature for heating the nip portion is controlled and a heater region 11b2 in which the temperature for heating the nip portion is controlled by contact with the region 17a2 are provided, and the nip is heated in the heater region 11b1. The difference between the temperature of the region and the temperature of the nip region heated in the heater region 11b2 is zero, or the calorific value of the heater region 11b1 and the calorific value of the heater region 11b2 are the same. The calorific value of the heater region 11b1 is set to be larger than the calorific value of the heater region 11b2 so as to be smaller. [Selection diagram] FIG. 8

Description

  The present invention relates to an image heating device.

In a heat fixing device as an image heating device provided in an image forming apparatus employing an electrophotographic method, an electrostatic recording method, or the like, a film heating device that does not supply power to the fixing device during standby and suppresses power consumption as low as possible. A fixing device of a system has been put to practical use.
2. Description of the Related Art In recent years, there have been various demands for image forming apparatuses such as copiers and printers, such as faster print speeds, improved quick start performance, energy savings, and compactness. Against this background, fixing devices of the film heating type are widely used.
In a fixing device of a film heating type, a film and a pressing member are disposed in pressure contact with each other, and a heater (heating body) for heating the film is disposed on an inner surface of a portion facing the pressing member inside the film. As a driving method of the film in such a fixing device, a driving roller is provided on the inner peripheral surface of the film to drive while applying tension to the film, or a pressure roller is driven loosely by a member supporting the film and driven. There is known a method in which the driven rotation is performed. In recent years, since the number of components is small, the latter pressure roller drive type is often adopted.

Here, in the fixing device of the film heating type, the temperature rise at the edge described below is cited as an existing problem.
When the recording material is passed through the fixing device and fixed, the surface temperature of the non-sheet passing area of the pressure roller (outside the area where the recording material passes when conveyed) may be excessively increased. This is because in the non-sheet passing area of the fixing nip where the recording material does not pass, heat is partially stored as much as there is no heat deprived by the recording material. This phenomenon is called a temperature rise at the end of the fixing device or a temperature rise at the non-sheet passing portion. When the temperature at the end rises to a high temperature, it has a thermal peak, which leads to hot offset, melting of the heater holder, and the like.
In order to solve the problem of the temperature rise at the end portion, a proposal has been made to arrange a heat conducting member between the back surface of the heater and the heater holder to make the temperature distribution of the heater uniform, as disclosed in Patent Document 1. As for the use of a heat conductive member, a proposal has been made to use the heat conductive member by electrically dividing it to ensure safety, as in Patent Document 2.

JP-A-11-84919 JP 2014-123100 A

However, in the case of the above-described related art, there is a concern that the following problems may occur.
In the configuration disclosed in Patent Literature 1, it is necessary to provide the heat conducting member with an insertion portion into the heater holder. This is because, if the positioning of the fixing nip in the longitudinal direction has not been performed on the heat conductive member, the heat conductive member has shifted, particularly when the heat conductive member has shifted from the end temperature rising portion, This is because there is a concern that the desired end-portion temperature rise suppression effect is not exhibited. However, when the heat conducting member is provided with the insertion portion to the heater holder, the heat capacity of the insertion portion is larger than that of the peripheral portion. Therefore, the soaking effect is promoted at the insertion portion, and the temperature of the heater is locally lowered, which may cause a fixing failure corresponding to the width of the insertion portion.
Further, when a plurality of heat conducting members are arranged as in the configuration disclosed in Patent Document 2, a gap is formed between the heat conducting members. Since the heater corresponding to the gap does not contact the heat conducting member, the soaking effect is reduced, the temperature of the heater locally increases, and image defects such as hot offset corresponding to the width of the gap may be caused. I am concerned.

  The present invention has been made in view of the circumstances described above, and is a technique capable of suppressing local temperature unevenness of a heater and obtaining a good image while maintaining a uniform heat effect of a heat conductive member. The purpose is to provide.

In order to achieve the above object, in the present invention,
A heater,
A heat conducting member arranged in contact with the heater, for uniformizing the temperature distribution of the heater,
A flexible sleeve rotatably provided and sliding on the heater;
A pressure member that forms the nip with the heater via the flexible sleeve;
Has,
An image heating apparatus for nipping, conveying, and heating a recording material on which a developer image is formed, between the flexible sleeve and the pressing member in the nip portion,
The heat conduction member includes a first region and a second region having a smaller heat capacity than the first region.
The heater includes:
A first heater region in which a temperature at which the nip portion is heated is controlled by contacting the first region, in a region of the heater that heats the nip portion;
A second heater region in which a temperature at which the nip portion is heated is controlled by contacting the second region, of a region of the heater that heats the nip portion;
Is provided,
The difference between the temperature of the nip area heated in the first heater area and the temperature of the nip area heated in the second heater area is zero or the heat generation in the first heater area. So as to be smaller than when it is assumed that the amount and the heat generation amount of the second heater area are the same.
The heat generation amount of the first heater region is set to be larger than the heat generation amount of the second heater region.

A heater,
A heat conducting member arranged in contact with the heater, for uniformizing the temperature distribution of the heater,
A flexible sleeve rotatably provided and sliding on the heater;
A pressure member that forms the nip with the heater via the flexible sleeve;
Has,
An image heating apparatus for nipping, conveying, and heating a recording material on which a developer image is formed, between the flexible sleeve and the pressing member in the nip portion,
A plurality of the heat conducting members are arranged with a gap along a longitudinal direction of the nip portion,
The heater includes:
A third heater region that is a region of the heater corresponding to a gap between adjacent heat conductive members of the plurality of heat conductive members;
A contact area that is an area of the heater with which the heat conductive member contacts,
Is provided,
The difference between the temperature of the nip area heated in the contact area and the temperature of the nip area heated in the third heater area is zero, or the calorific value of the contact area, In order to be smaller than when assuming that the heat value of the third heater area is the same,
The heat generation amount of the third heater region is set to be smaller than the heat generation amount of the contact region.

  ADVANTAGE OF THE INVENTION According to this invention, while maintaining the heat equalizing effect of a heat conductive member, it becomes possible to suppress the local temperature unevenness of a heater and to obtain a favorable image.

Sectional view showing a schematic configuration of an image forming apparatus according to an embodiment. FIG. 1 is a diagram illustrating a schematic configuration of a fixing device according to an embodiment. FIG. 1 is a schematic diagram illustrating a heater according to an embodiment. Schematic diagram of a configuration in which no heat conducting member is arranged on the back of the heater FIG. 3 is a schematic cross-sectional view of the configuration of the present embodiment in which a heat conductive member is arranged on the back surface of the heater The figure which shows the structure in which the position of the longitudinal direction of a heat conductive member is not regulated. FIG. 2 is a schematic diagram illustrating a dimensional relationship of a single heat conductive member according to the first embodiment. FIG. 3 is a diagram illustrating a dimensional relationship between a heat conductive member and a heater according to the first embodiment. Diagram showing temperature distribution measurement results over the entire longitudinal direction FIG. 7 is a diagram illustrating a dimensional relationship between a heat conducting member and a heater in the second embodiment. FIG. 5 is a schematic diagram for explaining a cross-sectional shape of a holder according to the second embodiment. Diagram showing temperature distribution measurement results over the entire longitudinal direction FIG. 9 is a schematic diagram illustrating a dimensional relationship of each heat conduction member in Embodiment 3 alone. The figure which shows the dimension relationship of the heat conductive member and a heater in Example 3. Diagram showing temperature distribution measurement results over the entire longitudinal direction

  Embodiments for carrying out the present invention will be illustratively described in detail below with reference to the drawings. However, the dimensions, materials, shapes, relative arrangements, and the like of the components described in this embodiment should be appropriately changed depending on the configuration of the apparatus to which the invention is applied and various conditions. It is not intended to limit the scope to the following embodiments.

(1) Image Forming Apparatus FIG. 1 is a cross-sectional view illustrating a schematic configuration of an image forming apparatus according to the present embodiment. In the present embodiment, a transfer type electrophotographic process type laser printer will be described as an image forming apparatus.
In FIG. 1, reference numeral 1 denotes a rotating drum type electrophotographic photosensitive member (hereinafter, photosensitive drum) as an image carrier, which is rotated at a predetermined frequency (process speed) in the direction of arrow a. The photosensitive drum 1 has a configuration in which a photosensitive material layer such as OPC or amorphous Si is formed on the outer peripheral surface of a cylindrical (drum) -shaped conductive base such as aluminum or nickel. The surface of the photosensitive drum 1 is uniformly charged to a predetermined polarity and potential by the charging roller 2 during the rotation process. Thereafter, the charged surface of the photosensitive drum 1 is subjected to a scanning exposure L by a laser beam according to the image information from the laser beam scanner 3 so that a latent image (static) corresponding to the target image information is formed on the photosensitive drum surface. (Electrostatic latent image) is formed. The latent image is developed by toner (developer) T in the developing device 4 and is visualized. As a development method, a jumping development method, a two-component development method, an FEED development method, or the like is used, and a combination of image exposure and reversal development is often used.

On the other hand, the recording material P accommodated in the feeding cassette 9 is fed out one by one by the driving of the feeding roller 8, and the pressure contact portion of the photosensitive drum 1 and the transfer roller 5 passes through a sheet path having a guide / registration roller. At a predetermined control timing. When a positive transfer bias is applied to the transfer roller 5 by a transfer bias application power supply, a negative toner image (developer image) on the surface of the photosensitive drum 1 is transferred onto the recording material P at the transfer nip portion. You.
Thereafter, the recording material P on which the toner image has been transferred in the transfer nip portion is introduced into a heat fixing device (hereinafter, fixing device) 6 as an image heating device, and undergoes a heat fixing process of the toner image. The fixing device 6 will be described in detail in section (2). The recording material P that has passed through the fixing device 6 is printed out on a discharge tray through a sheet path having a conveying roller, a guide, and a discharge roller. The surface of the photosensitive drum 1 that has passed through the transfer nip is cleaned by a cleaning device 7 to remove extraneous matter such as untransferred toner, and is repeatedly provided for image formation.

(2) Fixing device 6
2A and 2B are diagrams showing a schematic configuration of the fixing device 6 of the present embodiment. FIG. 2A is a sectional view of the fixing device 6, FIG. 2B is a sectional view of a heater, and FIG. FIG. 3 is an exploded perspective view of the fixing device 6.
The fixing device 6 of the present embodiment is basically a film heating type fixing device including a fixing assembly 10 and a pressure roller 20 that form a nip portion N by pressing each other. As shown in FIGS. 2A and 2C, the fixing assembly 10 mainly receives the pressing force from the fixing film 13, the heater 11, the heat conductive member 17, the holder 12, and the pressing spring 15, and fixes the holder 12. It is composed of a metal stay 14 pressed against the pressure roller 20.

[Fixing film 13]
The fixing film 13 is rotatably provided and corresponds to a flexible sleeve that slides on the heater 11. In the present embodiment, the fixing film 13 is a heat-resistant film having a total thickness of 200 μm or less to enable quick start. The fixing film 13 is formed as a base layer of a heat-resistant resin such as polyimide, polyamide-imide, or PEEK, or a pure metal or alloy having heat resistance and heat conductivity, such as SUS, Al, Ni, Cu, or Zn. In the case of a resin base layer, a heat conductive powder such as BN, alumina, or Al may be mixed in order to improve the heat conductivity. Further, in order to constitute a fixing device having a long service life, the fixing film 13 having sufficient strength and excellent durability needs to have a total thickness of 20 μm or more. Therefore, the total thickness of the fixing film 13 is optimally not less than 20 μm and not more than 200 μm.

  Furthermore, in order to prevent offset and ensure the separation of the recording material, a heat-resistant resin having a good releasability such as a fluororesin such as PTFE, PFA, FEP, ETFE, CTFE, and PVDF, or a silicone resin is mixed or used alone in the surface layer. It is coated to form a release layer. Here, PTFE is polytetrafluoroethylene, PFA is a tetrafluoroethylene perfluoroalkyl vinyl ether copolymer, and FEP is a tetrafluoroethylene hexafluoropropylene copolymer. In addition, ETFE is an ethylene tetrafluoroethylene copolymer, CTFE is polychlorotrifluoroethylene, and PVDF is polyvinyl denfluoride.

  As a coating method, a method in which the outer surface of the fixing film 13 is subjected to an etching treatment and then the release layer is dipped or a powder spray or the like may be applied. Alternatively, a method in which a resin formed in a tube shape is covered on the surface of the fixing film 13 may be used. Alternatively, a method may be used in which after the outer surface of the fixing film 13 is blasted, a primer layer as an adhesive is applied to cover the release layer. In this embodiment, a fixing film having a total thickness of 75 μm and an outer diameter of φ18 mm made of PFA having a surface layer (release layer) having a thickness of 10 μm, a primer layer having a thickness of 5 μm, and a base layer having a thickness of 60 μm was used.

[Heater 11]
As shown in FIG. 2B, the heater 11 serving as a heating member heats the nip N by contacting the inner surface of the fixing film 13. The heater 11 has a plate shape with a low heat capacity. A resistance heating element 11b such as Ag / Pd (silver palladium), RuO ₂ , Ta ₂ N is screened on the surface of an insulating ceramic substrate 11a such as alumina or aluminum nitride along the longitudinal direction of the nip portion N. It is formed by printing or the like. At this time, the resistance heating element 11b is formed with a thickness of about 10 μm and a width of about 1 to 5 mm.
On the surface of the heater 11 in contact with the fixing film 13, a protective layer 11c is provided to protect the resistance heating element within a range that does not impair the thermal efficiency. It is desirable that the thickness of the protective layer is sufficiently small and the surface property is good. Generally, a glass coat of about 30 to 200 μm is used. In the following description, the longitudinal direction of the nip N is simply referred to as the longitudinal direction.

Here, there is a configuration in which the width of the resistance heating element is made narrower than the other parts to increase the partial resistance to increase the amount of heat generation, and has been put to practical use. In the following description, a portion in which the width of the resistance heating element is reduced is referred to as an aperture portion, a portion in which the width of the resistance heating element is increased is referred to as an inverted aperture portion, and a change in the width is referred to as an aperture amount. The aperture amount is an amount indicating what percentage of the resistance heating element is in a unit area when the resistance value per unit area of the resistance heating element other than the aperture section is 100%, and the thickness of the resistance heating element is constant. Assuming that there is no partial variation in the volume resistance value of the resistance material, it is expressed by the following equation.
Aperture amount (%) = (width of resistance heating element other than aperture) / (width of resistance heating element at aperture)
Since the resistance value and the calorific value are proportional, the throttle amount may be considered as a ratio of the calorific value per unit area. The heater 11 will be described in detail in the section (4).

[Pressing roller 20]
The pressure roller 20 as a pressure member is an elastic roller in which an elastic layer 22 is formed on the outer peripheral side of a metal core 21 made of SUS, SUM, Al, or the like. Examples of the elastic layer 22 include an elastic solid rubber layer formed of heat-resistant rubber such as silicone rubber and fluorine rubber, and an elastic sponge rubber layer formed by foaming silicone rubber to provide a more heat insulating effect. Further, as the elastic layer 22, an elastic foam rubber layer in which hollow fillers (micro balloons or the like) are dispersed in a silicone rubber layer and a gas part is provided in a cured product to enhance a heat insulating effect can be exemplified. Further, a release layer such as a perfluoroalkoxy resin (PFA) or a polytetrafluoroethylene resin (PTFE) may be formed on the outer peripheral side of the elastic layer 22. In the present embodiment, a pressure roller having an outer diameter of 20 mm using Al as the metal core 21, silicon rubber as the elastic layer 22, and PFA as the release layer was used.

[Heat conductive member 17]
The heat conducting member 17 is arranged in contact with the heater 11 to make the temperature distribution of the heater 11 uniform. In the present embodiment, the heat conductive member 17 is held between the heater 11 and the holder 12 as a holding member for holding the heater 11, and is formed of an insulating ceramic substrate 11a of the heater 11 made of alumina, aluminum nitride, or the like. It is made of a material having better heat conductivity. Examples of the heat conductive member 17 include a graphite sheet obtained by processing Al, Cu, Ag, and graphite into a sheet. It is desirable that the thermal conductivity of the thermal conductive member 17 be higher than at least the thermal conductivity of the substrate 11 a of the heater 11. The heat conductive member 17 will be described in detail in section (4).

[Driving and Control Method of Fixing Device 6]
The fixing assembly 10 is pressed against the elasticity of the pressure roller 20 by the following configuration to form a predetermined nip portion N. That is, as shown in FIG. 2 (c), both ends of the metal stay 14 in the longitudinal direction protrude from the holder 12, and the spring receiving portions 14a at both ends of the stay are pressed by the pressing springs 15a through the spring receiving members. Pressurized. The load is transmitted uniformly over the longitudinal direction of the holder 12 via the stay feet 14b. In the nip portion N, the fixing film 13 is bent by being sandwiched between the heater 11 and the pressure roller 20 by the pressing force, so that the fixing film 13 comes into close contact with the heating surface of the heater 11.

The pressure roller 20 obtains a driving force that rotates in a direction indicated by an arrow in FIG. 2A from a drive gear (not shown) provided at an end of the core 21. This driving force is transmitted by a motor (not shown) according to a command from a CPU (not shown) that controls the control means. With the rotation of the pressure roller 20, the fixing film 13 is driven to rotate by the frictional force with the pressure roller 20. By interposing a lubricant such as a heat-resistant grease such as a fluorine-based or silicone-based grease between the fixing film 13 and the heater 11, the frictional resistance is suppressed low, and the fixing film 13 can rotate smoothly.

  Further, the temperature of the heater 11 is controlled by appropriately determining and controlling the duty ratio and the wave number of the voltage applied to the energized heating resistance layer by the CPU in accordance with a signal from a thermistor (not shown) which is a thermal element. The temperature inside the fixing nip is kept at a predetermined fixing set temperature. The holder 12 is provided with a through hole, and the thermistor is arranged so as to contact the heat conducting member 17 from the through hole. That is, the heat-sensitive element is arranged so as to heat the heat of the heater 11 via the heat conductive member 17. The recording material P holding the unfixed toner image is appropriately supplied by a supply unit (not shown) at a predetermined timing, is conveyed into the nip N, and is heated and fixed. The recording material P that has been heated and fixed while being nipped and conveyed in the nip portion N is guided by a discharge guide (not shown) and discharged.

(3) Influence of Heat Conduction Member 17 In this section, the effect of the heat conduction member 17 will be described in detail.
3A and 3B are schematic diagrams showing the heater 11 of the present embodiment. FIG. 3A is a plan view of the heater 11, FIG. 3B is a cross-sectional view of the heater 11, and FIG. FIG. 3D is a side view of the heat conducting member 17.
As shown in FIG. 3A, the heater 11 is formed by forming a resistance heating element 11b of Ag / Pd (silver palladium) on an alumina substrate by screen printing, and further connecting an electrical contact to the resistance heating element 11b. . The two resistance heating elements 11b are connected in series, and have a resistance value of 14Ω. As shown in FIG. 3B, a glass coat having a thickness of 60 μm was formed as the protective layer 11c so as to cover the resistance heating element 11b. The substrate 11a has a rectangular parallelepiped shape having a length in the longitudinal direction of 270 mm, a length in the transverse direction of 6.0 mm, and a thickness of 1 mm. Here, a direction orthogonal to the longitudinal direction on the substrate 11a is referred to as a lateral direction. The short direction is the same direction as the conveying direction of the recording material conveyed in the nip N (recording material conveying direction).

The resistance heating element 11b has a pattern folded at an end in the longitudinal direction via an electrical contact portion, and two resistance heating elements 11b extending in the longitudinal direction are arranged side by side in the recording material conveyance direction. The resistance heating elements 11b located in the upstream and downstream directions in the recording material conveyance direction are formed in the same shape (there is no drawing shape in the pattern), and the length in the longitudinal direction is 218 mm (on both sides in the longitudinal direction with respect to the paper passing center O). Each is 109 mm), and the length in the short direction is 1.0 mm.
Here, the center position in the longitudinal direction of the area through which the recording material passes when transported is defined as a paper passing center O. Further, an end having an electrical contact portion at a longitudinal end of the heater 11 is referred to as a power supply portion 11d, and an end having a folded pattern is referred to as a folded portion 11e. In the present embodiment, the thermistor (not shown) is arranged at a position 25 mm outside in the longitudinal direction from the paper passing center O. When the position of the thermistor is shown in the figure, it is indicated in the figure by using the symbol S.
Further, as shown in FIGS. 3C and 3D, the heat conductive member 17 is a uniform metal plate made of aluminum (pure aluminum, alloy number A1050), and has a longitudinal length of 218 mm. (109 mm on both sides in the longitudinal direction with respect to the paper passing center O), the width is 6 mm, and the thickness is 0.3 mm.

FIG. 4A is a schematic cross-sectional view of a configuration in which the heat conductive member 17 is not provided on the back surface of the heater 11, and FIG. 5A is a configuration of the present embodiment in which the heat conductive member 17 is provided on the back surface of the heater 11. It is an outline sectional view. Since the aluminum metal plate as the heat conductive member 17 thermally expands, a gap of 1 mm or more is provided between both ends of the heat conductive member 17 in the longitudinal direction and the holder 12. Here, the back surface of the heater 11 in contact with the heat conductive member 17 refers to the surface of the substrate 11a opposite to the surface on which the resistance heating element 11b is formed.
As a case where the temperature rise at the edge described in the background art is a problem, a recording material having a width smaller than the width of the resistance heating element 11b and having a high fixing control temperature (a recording material having a large basis weight) is continuously used. Printing is generally known.
Therefore, the evaluation method of the temperature distribution in the entire region in the longitudinal direction was as follows. If the temperature of the end heating section exceeds 250 ° C., problems occur in the fixing performance and the durability of the pressure roller 20, and if it exceeds 300 ° C., the melting of the holder starts. The method of evaluating the end temperature rise will be described in detail below.

[Evaluation method of temperature distribution in the entire longitudinal direction]
Environment: 15 ° C / 10%
Paper type: A4 (210 mm width) size, plain paper passing mode with a basis weight of 128 g / m ² : Continuous printing from cold state Print speed: about 220 mm / s
Fixing control temperature: 230 ° C
When 250 sheets of recording material were passed by the above-mentioned paper passing method, the surface temperature of the pressure roller 20 was measured by a thermo tracer (TH9100 manufactured by Nippon Avionics Co., Ltd.).

FIG. 4B is a diagram for describing the result of evaluating the end-portion temperature rise in a configuration in which the heat conductive member 17 is not disposed on the back surface of the heater 11 (of a comparative example).
The paper passing area (the area that passes when the recording material is conveyed) is temperature-controlled using a thermistor (not shown), and the surface temperature of the pressure roller 20 is stable at about 80 ° C. In the non-sheet passing area, a thermal peak was located at a position 2 to 3 mm outside the end of the recording material to be passed, and the maximum temperature was 270 ° C. The temperature in the non-sheet passing area exceeded 250 ° C., which was a temperature at which there was a problem in fixing performance and durability of the pressure roller.

FIG. 5B is a diagram for explaining the result of evaluating the end portion temperature rise in the configuration (of the present embodiment) in which the heat conductive member 17 is disposed on the back surface of the heater 11.
The temperature of the paper passing area is controlled using a thermistor (not shown), and the surface temperature of the pressure roller 20 is stable at about 80 ° C.
In the non-sheet passing area, although a thermal peak is located at a position 2 to 3 mm outside the edge of the recording material to be passed, the maximum temperature is 230 ° C., and the temperature is suppressed to a temperature at which no problem such as fixing performance occurs. did it. By arranging a heat conducting member that is more heat conducting than the insulating ceramic substrate on the back surface of the heater 11, heat can easily move in the thickness direction, the width direction, and the length direction. The gradient is greatly reduced.
The area through which the recording material is passed is repeatedly heated by the recording material and cooled, and the total amount of moving heat is proportional to the temperature gradient. Will move. On the other hand, as described in the subject, if the position of the heat conducting member 17 in the longitudinal direction is not regulated, there is a concern that a problem may occur in which the effect of suppressing the end portion temperature rise cannot be obtained.

FIG. 6 is a diagram for explaining a configuration in which the heat conductive member 17 is arranged on the back surface of the heater 11, but the position of the heat conductive member 17 in the longitudinal direction is not restricted. FIG. 6A shows a state where the heat conducting member 17 is arranged at a desired position as shown in FIG. FIG. 6B shows a state in which the heat conductive member 17 is shifted by 1 mm to the right side (the side of the power supply unit 11d) in the figure. FIG. 6C shows a state shown in FIG. The result of evaluating the temperature rise at the end when the heat conducting member 17 is shifted is shown.
As shown in FIG. 6C, the maximum temperature rises from 230 ° C. to 250 ° C. on the left side (turning portion 11e side), and the maximum temperature rises from 230 ° C. to 210 ° C. on the right side (feeding portion 11d side). Improved. In the region where the maximum temperature reached 250 ° C., fixing failure occurred.
The above phenomenon is related to the heat capacity of the heat conductive member 17 immediately below the thermal peak position in the portion where the temperature of the end is rising.

  FIGS. 6D and 6E are diagrams showing the volume of the heat conducting member 17 immediately below the thermal peak position in the portion where the temperature of the end is rising. FIG. 6D shows the left side (the folded portion 11e side) of the heat conducting member 17 shown in FIG. 6B, and FIG. 6E shows the heat conducting member shown in FIG. 6B. 17 shows the right side (on the power supply unit 11d side). FIG. 6D shows that the volume of the heat conductive member 17 is shifted by 1 mm to the right (to the side of the power supply unit 11d), thereby reducing the volume by 25%. In FIG. This indicates that the volume has increased by 25% due to the shift of 1 mm to the side of the power supply unit 11d.

According to the examination results of the present inventors, it was found that when the heat capacity of the heat conducting member 17 was increased, the temperature of the heater 11 at the position where the heat capacity was increased was reduced, and the effect of suppressing the end portion temperature rise was high. Since the heat capacity is represented by the product of the mass of the material (the product of the volume and the specific gravity) and the specific heat, increasing the volume of the heat conducting member 17 will increase the heat capacity. That is, in the present embodiment, the change in the heat capacity of the heat conductive member 17 is 25%, and the change in the surface temperature of the pressure roller 20 is 20 ° C. (= 0.8 ° C./%).
From the above, it can be seen that in order to exhibit the desired end-portion temperature rise suppression effect, the heat conducting member 17 must not move in the longitudinal direction and must be regulated in position.

(4) Example Hereinafter, the present invention will be described in detail with reference to specific examples. In the examples described below, the same components as those in the above-described embodiment are denoted by the same reference numerals, and description thereof will be omitted.
(Example 1)
The first embodiment will be described below.
7A and 7B are schematic diagrams showing a dimensional relationship of the heat conductive member 17 alone in this embodiment. FIG. 7A is a perspective view, and FIGS. It is the figure seen from the direction shown by arrow bd. FIG. 8 is a diagram illustrating a dimensional relationship between the heat conductive member 17 and the heater 11 in the present embodiment.
In this embodiment, one metal plate is used as the heat conducting member 17. As a configuration for positioning the heat conducting member 17 in the longitudinal direction, a bent portion (projection portion) 17a that is the same as (integral with) the metal plate is provided, and the bent portion 17a is inserted into a through hole provided in the holder 12, and The configuration was made to match. The through hole is slightly larger than the bent portion 17a in order to absorb the thermal expansion of the metal plate.

Here, the heat capacity of the metal plate and the amount of heat generated by the heater 11 when the bent portion 17a is provided on the metal plate will be described.
When the bent portion 17a is provided on the metal plate, the heat capacity of the region 17a1 of the metal plate including the bent portion 17a is larger than the heat capacity of the region 17a2 not including the bent portion 17a. At this time, since the heat capacity of the region 17a1 differs from that of the region 17a2 in the metal plate, there is a concern that local temperature unevenness may occur in the heater 11.
Therefore, in the present embodiment, the heat value of the heater 11 is set as follows based on the relationship between the heat capacity and the temperature of the heater described above.
Here, of the area of the heater 11 for heating the nip N, the area where the temperature for heating the nip N is controlled (adjusted or changed) by contact with the area 17a1 of the heat conducting member 17 is defined as the heater area 11b1. And Further, among the regions of the heater 11 for heating the nip N, the region where the temperature for heating the nip N is controlled by the contact of the region 17a2 of the heat conducting member 17 is referred to as a heater region 11b2. The region 17a1 is a region including the bent portion 17a (a region surrounded by a dotted line in the heat conducting member 17 shown in FIG. 8) in a region along the lateral direction of the metal plate, and the region 17a2 is a metal region. This is an area of the plate other than the area 17a1. The region 17a1 and the region 17a2 are arranged side by side in the longitudinal direction.
At this time, in the present embodiment, the heat generation amount of the heater region 11b1 is set to be smaller than that of the heater region 11b2 so that the difference between the temperatures of the nip portions N heated in the heater region 11b1 and the heater region 11b2 becomes zero. Is also set to a large value. Here, the difference between the temperatures does not have to be zero, and may be smaller than the case where the heat generation amount of the heater region 11b1 and the heat generation amount of the heater region 11b2 are the same.

Hereinafter, the present embodiment will be described more specifically.
The heat conductive member 17 has the same basic shape as that described with reference to FIG. 3. As shown in FIG. 7, the material is a uniform metal plate made of an aluminum material (pure aluminum, alloy number A1050). Has a length of 218 mm, a width of 6 mm, and a thickness of 0.3 mm. The bent portion 17a serving as a positioning portion in the longitudinal direction of the heat conductive member 17 is located at a position 80 to 84 mm away from the paper passing center O to the left side (the folded portion 11e side) as shown in FIGS. 7B and 7C. It is formed in a size of 4 mm in width and 3 mm in length. In view of the deviation force that may occur due to the manufacturing tolerance of the fixing device in the present embodiment, the width is required to be 4 mm or more and the length is required to be 2 mm or more in order to sufficiently secure the strength of the bent portion 17a. .

In the present embodiment, the shapes and dimensions of the substrate 11a and the resistance heating element 11b of the heater 11 shown in FIG. 8 exclude the length in the short direction of the resistance heating element 11b in the heater area 11b1 corresponding to the bent portion 17a of the metal plate. The operation is the same as that of the embodiment shown in FIG.
Here, the length in the short direction of the resistance heating element 11b in the heater region 11b1 corresponding to the bent portion 17a of the metal plate was defined as L. The length in the short direction of the resistance heating element 11b in the heater area 11b2 is 1 mm. At this time, in this embodiment, it is assumed that L = 0.93 mm (the aperture shape is present in the resistance heating element patterns on both the upstream and downstream sides in the recording material conveyance direction), and that L = 1 mm (there is no aperture shape in the resistance heating element pattern). This is referred to as Comparative Example 1.
In the present embodiment, the aperture shape is provided in the resistance heating element pattern on both the upstream and downstream sides in the recording material transport direction. However, if a desired heat generation amount can be obtained, one of the upstream and downstream in the recording material transport direction is provided. The aperture shape may be provided only in the pattern.

In performing the performance evaluation of the present example and comparative example 1, the temperature distribution was measured over the entire area in the longitudinal direction described in detail in section (3). FIG. 9A is a diagram showing a temperature distribution measurement result over the entire region in the longitudinal direction of Comparative Example 1. Although the recording material to be passed has a thermal peak at a position 2 to 3 mm outside from the position of the end in the nip portion N, the maximum temperature is 230 ° C., and due to the effect of the metal plate as the heat conducting member 17. The temperature rise at the end could be sufficiently suppressed.
However, the pressure roller surface temperature corresponding to the bent portion 17a of the metal plate was lower than the ambient temperature, resulting in temperature unevenness. The temperature non-uniformity was about 10 ° C., which sometimes caused defective fixing.
In Comparative Example 1 and the present example, the bent portion 17a was provided in the same manner as the metal plate so that the metal plate did not move in the longitudinal direction. However, in Comparative Example 1, the heat capacity of the portion was reduced by providing the bent portion 17a. The number of the fixing devices was lower than that of the surroundings, resulting in low-temperature portions.

FIG. 9B is a diagram illustrating a measurement result of the temperature distribution in the entire region in the longitudinal direction according to the present embodiment. Similarly to the result of Comparative Example 1, although the recording material to be passed has a thermal peak at a position 2 to 3 mm outside from the end of the nip portion N, the maximum temperature is 230 ° C. Due to the effect of the metal plate as the member 17, the temperature rise at the end could be sufficiently suppressed. Furthermore, in the bent portion 17a of the metal plate, there was no temperature unevenness as in Comparative Example 1, and no image defect occurred.
This is because the aperture shape is provided in the heater area 11b1 of the resistance heating element pattern corresponding to the area 17a1 of the metal plate in which the heat capacity is larger than the surrounding area by providing the bent portion 17a. This is because the amount of heat generated in the heater region 11b1 has increased. In other words, this is because the amount of heat generated by the heater is increased by providing an aperture shape in the resistance heating element pattern in a region where the temperature of the fixing device is likely to be low.

  As described above, according to the present embodiment, even when the positioning portion is provided on the heat conducting member 17, the heat generation amount of the heater 11 in the region corresponding to the positioning portion is increased, so that the heat conducting member 17 , The local temperature unevenness can be suppressed. This makes it possible to obtain a better image.

Here, in the present embodiment, the mode in which the local temperature unevenness is suppressed when the bent portion 17a is provided as the positioning portion in the heat conductive member 17 has been described, but the present invention is not limited to this. The present invention can be suitably applied to a case where the heat conducting member for making the temperature distribution of the heater uniform is composed of a plurality of regions having different heat capacities.
That is, when there is a region where the heat capacity is larger (smaller) than the other regions in the heat conductive member, the heat generation amount of the heater region corresponding to the region is increased (smaller), so that the heat conductive member has It is possible to suppress local temperature unevenness while maintaining the effect of suppressing the end portion temperature rise.
Further, in the present embodiment, the bent portion 17a is formed integrally with the metal plate. However, the present invention is not limited to this, and the bent portion 17a may be formed separately from the metal plate.

(Example 2)
Hereinafter, a second embodiment will be described. In this embodiment, the same components as those in the first embodiment are denoted by the same reference numerals, and description thereof will be omitted.
FIG. 10A is a diagram illustrating a dimensional relationship between the heat conductive member 17 and the heater 11 in the present embodiment, and FIG. 10B is a schematic perspective view illustrating the heat conductive member 17 alone in the present embodiment. . FIG. 11 is a schematic diagram for explaining a cross-sectional shape of the holder 12 in the present embodiment.
In this embodiment, as in the first embodiment, one metal plate was used as the heat conducting member 17. As a configuration for positioning the heat conductive member 17 in the longitudinal direction, the bent portion 17a is provided in the first embodiment, but the following concave portion 17b is provided in the present embodiment. That is, in the present embodiment, a concave portion 17b is provided by forming a shape (hereinafter referred to as a narrow portion 17c) in which the width in the short direction is narrower than the surroundings in a part of the metal plate. Was fitted (engaged) with the boss 12a provided on the boss.

Here, the heat capacity of the metal plate and the amount of heat generated by the heater 11 when the concave portion 17b is provided in the metal plate will be described.
By providing the concave portion 17b in the metal plate, the heat capacity of the narrow portion 17c (the region including the concave portion 17b in the short direction) of the metal plate is reduced in the area other than the narrow portion 17c (not including the concave portion 17b in the short direction). Area) 17c1. At this time, there is a concern that local temperature unevenness may occur in the heater 11 due to the difference in heat capacity between the narrow portion 17c and the region 17c1 in the metal plate.
Therefore, in the present embodiment, the amount of heat generated by the heater 11 is set as follows. Here, among the regions of the heater 11 that heat the nip portion N, a region where the temperature at which the nip portion N is heated is controlled by the contact of the narrow portion 17c of the heat conducting member 17 is referred to as a heater region 11b3. Further, in the present embodiment, the heater region 11b2 is a region where the temperature at which the nip portion N is heated is controlled by the contact of the region 17c1 of the heat conducting member 17 in the region of the heater 11 which heats the nip portion N. Becomes
At this time, in the present embodiment, the heat generation amount of the heater region 11b3 is set to be smaller than that of the heater region 11b2 such that the difference in temperature between the nip portion N heated in the heater region 11b2 and the heater region 11b3 becomes zero. Also set smaller. Here, the difference between the temperatures does not have to be zero, and may be smaller than the case where it is assumed that the heat generation amount of the heater region 11b2 and the heat generation amount of the heater region 11b3 are the same.

Hereinafter, the present embodiment will be described more specifically.
The heat conducting member 17 is a metal plate similar to that of the first embodiment, and has a length of 218 mm, a width of 6 mm and a thickness of 0.3 mm. As shown in FIG. 10A, the concave portion 17b serving as a positioning portion in the longitudinal direction of the heat conductive member 17 has a width of 4 mm at a position 80 to 84 mm away from the paper passing center O to the left side (the folded portion 11e side). It is formed to a size of 3 mm in depth.
In this embodiment, the shape and dimensions of the substrate 11a and the resistance heating element 11b of the heater 11 shown in FIG. 10A exclude the length in the short direction of the resistance heating element 11b at a position corresponding to the concave portion 17b of the metal plate. The operation is the same as that of the first embodiment shown in FIG. The length in the short direction of the resistance heating element 11b in the heater region 11b3 corresponding to the concave portion 17b of the metal plate is defined as L in this embodiment for convenience of explanation.
Here, in this embodiment, L = 1.07 mm (the reverse drawing shape is present in the resistive heating element patterns on both the upstream and downstream sides in the recording material conveyance direction), and L = 1 mm (no drawing shape is present in the resistive heating element pattern). This is referred to as Comparative Example 2.

In performing the performance evaluation of the present example and the comparative example 2, the temperature distribution was measured in the entire longitudinal direction described in detail in the section (3). FIG. 12A is a diagram showing a temperature distribution measurement result over the entire region in the longitudinal direction of Comparative Example 2.
In Comparative Example 2, as in Comparative Example 1, the temperature rise of the end portion was sufficiently suppressed by the effect of the metal plate serving as the heat conducting member 17. However, the surface temperature of the pressure roller corresponding to the concave portion 17b of the metal plate became higher than the ambient temperature, resulting in temperature unevenness. The temperature non-uniformity was about 10 ° C., which sometimes caused defective fixing.
In Comparative Example 2 and this example, the concave portion 17b was provided in the metal plate so that the metal plate did not move in the longitudinal direction. However, in Comparative Example 2, the provision of the concave portion 17b reduced the heat capacity of that portion compared to the surroundings. In this case, a high-temperature portion was generated as a fixing device.

FIG. 12B is a diagram showing the results of measuring the temperature distribution over the entire area in the longitudinal direction of this example. Similarly to the results of Comparative Example 2 and Example 1, the temperature rise at the end could be sufficiently suppressed by the effect of the metal plate as the heat conductive member 17. Furthermore, in the concave portion 17b of the metal plate, the temperature unevenness generated in Comparative Example 2 was greatly improved to about 2 ° C., and no fixing failure occurred.
This is because the provision of the concave portion 17b provides a reverse drawing shape in the heater region 11b3 of the resistance heating element pattern corresponding to the narrow portion 17c of the metal plate whose heat capacity becomes smaller than the surrounding portion. This is because the calorific value of the heater region 11b3 provided with the pattern has become smaller. In other words, this is because the amount of heat generated by the heater is reduced by providing an inverse drawing shape in the resistance heating element pattern in a region where the temperature of the fixing device is likely to increase.

  As described above, according to the present embodiment, when the concave portion 17b is provided in the heat conductive member 17, the amount of heat generated in the corresponding heater region 11b3 is reduced, thereby suppressing the temperature rise at the end of the heat conductive member 17. Local temperature unevenness can be suppressed while maintaining the effect. This makes it possible to obtain a better image.

(Example 3)
Hereinafter, a third embodiment will be described. In this embodiment, the same components as those in the first and second embodiments are denoted by the same reference numerals, and the description thereof will be omitted.
FIG. 13 is a schematic diagram showing a dimensional relationship of each of the heat conducting members 17 in the present embodiment alone, FIG. 13 (a) is a perspective view, and FIGS. It is the figure seen from the direction shown by arrow b-d in a). FIG. 14 is a diagram illustrating a dimensional relationship between the heat conductive member 17 and the heater 11 in the present embodiment.
In the present embodiment, a case will be described in which a plurality of metal plates as the heat conductive members 17 are arranged along the longitudinal direction with a gap therebetween. In the following description, a case where two metal plates are used will be described. . In this embodiment, a region (a section where no metal plate is present, a gap portion) between the two heat conducting members 17 arranged along the longitudinal direction is referred to as a gap 18.

Here, the amount of heat generated by the heater 11 when a plurality of metal plates are arranged along the longitudinal direction with a gap provided therebetween will be described.
When a plurality of metal plates are arranged along the longitudinal direction with a gap, the metal plate is not arranged in contact with the heater region 11b4 of the heater 11 corresponding to the gap portion 18, so that the metal plate is locally located in the heater 11. It is feared that a non-uniform temperature unevenness occurs.
In the present embodiment, the heating value of the heater region 11b4 is smaller than that of the heater region 11b2 such that the difference in temperature between the nip portion N heated in the heater region 11b4 and the region of the nip N heated in the heater region 11b2 becomes zero. Set. Here, the difference between the temperatures does not have to be zero, and may be smaller than the case where it is assumed that the heat generation amount of the heater region 11b4 and the heat generation amount of the heater region 11b2 are the same.
In the present embodiment, the positioning configuration of each metal plate is the same as that of the first embodiment, and the bent portions 17a provided on each heat conductive member 17 are respectively inserted into the plurality of through holes provided in the holder 12. did. By providing the bent portion 17a on the metal plate, there are regions having different heat capacities in the metal plate. At this time, heat generated by the heater regions of the heaters 11 corresponding to the regions of the metal plate having different heat capacities is obtained. The setting of the amount is the same as in the first embodiment.

Hereinafter, the present embodiment will be described more specifically.
The heat conducting member 17 is a metal plate similar to the first embodiment, and has a length of 106.5 mm, a width of 6 mm, and a thickness of 0.3 mm.
In this embodiment, the two metal plates are arranged so as to be symmetrical in the longitudinal direction with respect to the paper passing center O as shown in FIG. The bent portions 17a serving as positioning portions in the longitudinal direction of the heat conductive member 17 are 80 to 84 mm apart from the paper passing center O on both sides in the longitudinal direction with respect to the two metal plates as shown in FIG. It is formed at a distance of 4 mm in width and 3 mm in length. Further, the two heat conducting members 17 are arranged at an interval of 5 mm in the longitudinal direction.

In this embodiment, the shape and dimensions of the substrate 11a and the resistance heating element 11b of the heater 11 shown in FIG. 14 are the lengths in the short direction of the area of the resistance heating element 11b corresponding to the bent portion 17a and the gap 18 of the metal plate. Except for this, the configuration is the same as that of the first embodiment shown in FIG.
As shown in FIG. 14, in the present embodiment, the lengths in the short direction of the resistance heating element 11b of the heater region 11b1 corresponding to the bent portion 17a are defined as L1 and L2, respectively. Furthermore, the length in the short direction of the resistance heating element 11b in the heater region 11b4 corresponding to the gap 18 was defined as L3. In this embodiment, L1 = 0.93 mm, L2 = 0.93 mm, L3 = 1.1 mm (partially reduced and partially reversed drawn in the resistance heating element patterns on both the upstream and downstream sides in the recording material conveyance direction). I do. Further, Comparative Example 3 is a mode in which L1, L2, and L3 = 1 mm (there is no aperture shape in the resistance heating element pattern).

In performing the performance evaluation of the present example and comparative example 3, the temperature distribution was measured over the entire area in the longitudinal direction described in detail in section (3). FIG. 15A is a diagram showing a temperature distribution measurement result over the entire region in the longitudinal direction of Comparative Example 3.
In Comparative Example 3, as in Comparative Example 1, the temperature rise of the end portion was sufficiently suppressed by the effect of each metal plate having the heat conductive member 17. However, the pressure roller surface temperature corresponding to the bent portion 17a of each metal plate was lower than the ambient temperature, resulting in temperature unevenness. The temperature non-uniformity was about 10 ° C., which sometimes caused defective fixing.
Further, the temperature in the gap 18 was higher than the ambient temperature, resulting in temperature unevenness. The temperature unevenness was about 20 ° C., and in some cases, fixing failure occurred.

FIG. 15B is a diagram showing the results of measuring the temperature distribution over the entire area in the longitudinal direction of this example. Similarly to the results of Comparative Example 3 and Example 1, the temperature rise of the end portion was sufficiently suppressed by the effect of each metal plate as the heat conductive member 17. In the bent portion 17 of the metal plate, the temperature unevenness as occurred in Comparative Example 3 was greatly improved to about 2 ° C., and no fixing failure occurred.
As in the case of the first embodiment, the aperture shape is provided by providing the aperture shape in the area of the resistance heating element pattern corresponding to the area of the metal plate where the heat capacity becomes larger than the surrounding area by providing the bent portion 17a. This is because the amount of heat generated in the resistance heating element pattern area has increased. In other words, this is because the amount of heat generated by the heater is increased by providing an aperture shape in the resistance heating element pattern in a region where the temperature of the fixing device is likely to be low.

In the gap 18, the temperature unevenness as in Comparative Example 3 was greatly improved to about 3 ° C., and no image defect occurred.
This is because, by providing the reverse drawing shape in the area of the resistance heating element pattern corresponding to the gap 18 where the heat capacity is smaller than the surrounding area, the amount of heat generated in the resistance heating element pattern area provided with the reverse drawing shape is reduced. It is because. In other words, this is because the amount of heat generated by the heater is reduced by providing an inverse drawing shape in the resistance heating element pattern in a region where the temperature of the fixing device is likely to increase.

  As described above, in the present embodiment, in the case where a plurality of metal plates, which are heat conductive members, are used, the amount of heat generated by the heater 11 is increased at the positioning portion of the heat conductive member 17, and the metal plates are not in contact with each other. In the heater region (gap), the amount of heat generated by the heater is reduced. This makes it possible to suppress local temperature unevenness while maintaining the effect of suppressing the end-portion temperature rise of the heat conducting member 17, so that a better image can be obtained.

  Here, in the present embodiment, the case where the bent portion 17a is provided as in the first embodiment is described as the positioning configuration of each metal plate, but the present invention is not limited to this. As a positioning configuration of each metal plate, for example, the concave portion 17b of the second embodiment may be provided. In this embodiment, the positioning structure is provided for each metal plate. However, the present invention is not limited to this. Further, in the case where a plurality of metal plates as the heat conductive members 17 are arranged along the longitudinal direction with a gap provided therebetween, even if a positioning structure is not provided for each metal plate, There is a concern that the presence of the void may cause local temperature unevenness in the heater 11. In such a case, the temperature of the heater region 11b4 of the heater 11 corresponding to the gap portion 18 and the temperature of the nip portion N heated in the region of the heater 11 in contact with the metal plate (hereinafter referred to as the contact region), respectively. The heating value may be set so that the difference becomes zero. That is, the heat generation amount of the heater region 11b4 may be set smaller than that of the contact region so that the temperature difference becomes zero. Here, the difference between the temperatures does not have to be zero, and may be smaller than the case where it is assumed that the heat generation amount of the heater region 11b4 and the heat generation amount of the contact region are the same.

  6: fixing device, 11: heater, 11b1, 11b2: heater area, 13: fixing film, 17: heat conductive member, 17a1, 17a2: area, 20: pressure roller, N: nip portion

In order to achieve the above object, in the present invention,
A heater,
A heat conducting member arranged in contact with the heater, for uniforming a temperature distribution in a longitudinal direction of the heater,
A flexible sleeve rotatably provided and sliding on the heater;
A pressure member that forms the nip with the heater via the flexible sleeve;
Has,
An image heating apparatus for nipping, conveying, and heating a recording material on which a developer image is formed, between the flexible sleeve and the pressing member in the nip portion,
Wherein the heat conducting member includes a first region and a second region a small heat capacity per unit length in the first said longitudinal direction than the region, is provided,
The heating data is,
A first heater region in contact with the front Symbol first region,
A second heater region in contact with the front Stories second region,
Is provided ,
The amount of heat generated per unit length in the longitudinal direction before Symbol first heater region is characterized by being larger than the amount of heat generated per unit length in the longitudinal direction of the second heater region.

A heater,
A heat conducting member arranged in contact with the heater, for uniforming a temperature distribution in a longitudinal direction of the heater,
A flexible sleeve rotatably provided and sliding on the heater;
A pressure member that forms the nip with the heater via the flexible sleeve;
Has,
An image heating apparatus for nipping, conveying, and heating a recording material on which a developer image is formed, between the flexible sleeve and the pressing member in the nip portion,
The heat conductive member, the front along the Sulfur butterfly side direction, a plurality of arranged with a gap,
The heater motor includes a contact region in which the heat conduction member is in contact, and a third heater region that corresponds to the gap portion, is provided,
The heat generation amount per unit length in the longitudinal direction of the third heater region is set to be smaller than the heat generation amount per unit length in the longitudinal direction of the contact region.

Claims (12)

A heater,
A heat conducting member arranged in contact with the heater, for uniformizing the temperature distribution of the heater,
A flexible sleeve rotatably provided and sliding on the heater;
A pressure member that forms the nip with the heater via the flexible sleeve;
Has,
An image heating apparatus for nipping, conveying, and heating a recording material on which a developer image is formed, between the flexible sleeve and the pressing member in the nip portion,
The heat conduction member includes a first region and a second region having a smaller heat capacity than the first region.
The heater includes:
A first heater region in which a temperature at which the nip portion is heated is controlled by contacting the first region, in a region of the heater that heats the nip portion;
A second heater region in which a temperature at which the nip portion is heated is controlled by contacting the second region, of a region of the heater that heats the nip portion;
Is provided,
The difference between the temperature of the nip area heated in the first heater area and the temperature of the nip area heated in the second heater area is zero or the heat generation in the first heater area. So as to be smaller than when it is assumed that the amount and the heat generation amount of the second heater area are the same.
The image heating apparatus according to claim 1, wherein a heat value of the first heater region is set to be larger than a heat value of the second heater region. Having a holding member for holding the heat conducting member,
The first region of the heat conducting member is provided with a protrusion that engages with the holding member,
2. The image heating apparatus according to claim 1, wherein the first region has the protrusion, and thus has a larger heat capacity than the second region. 3. Having a holding member for holding the heat conducting member,
The second region of the heat conductive member is provided with a concave portion that engages with the holding member,
The image heating apparatus according to claim 1, wherein the second region has the concave portion and has a smaller heat capacity than the first region. The image heating apparatus according to claim 2, wherein the projecting portion is a positioning portion that positions the heat conductive member with respect to the holding member in a longitudinal direction of the nip portion. The image heating apparatus according to claim 3, wherein the concave portion is a positioning portion that positions the heat conductive member with respect to the holding member in a longitudinal direction of the nip portion. The heater has a substrate and a heating element formed on the substrate so as to extend in a longitudinal direction of the nip portion,
In a direction orthogonal to the longitudinal direction of the heating element, the width of the heating element in the first heater area is formed to be narrower than the width of the heating element in the second heater area. The image heating apparatus according to claim 1, wherein a heat value is set to be larger than a heat value of the second heater area. A plurality of the heat conducting members are arranged with a gap along a longitudinal direction of the nip portion,
The heater includes a third heater region that is a region of the heater corresponding to a gap between adjacent heat conductive members of the plurality of heat conductive members,
The difference between the temperature of the nip region heated by the first heater region or the second heater region and the temperature of the nip region heated by the third heater region is zero, or The heat generation amount of the first heater region or the second heater region and the heat generation amount of the third heater region are smaller than when it is assumed that they are the same.
The image according to any one of claims 1 to 6, wherein a heat value of the third heater region is set to be smaller than a heat value of the first heater region or the second heater region. Heating equipment. The heater has a substrate and a heating element formed on the substrate so as to extend in a longitudinal direction of the nip portion,
In a direction perpendicular to the longitudinal direction of the heating element, the width of the heating element in the third heater area is formed wider than the heating element in the first heater area and the heating element in the second heater area. The image heating apparatus according to claim 7, wherein a heat value of the third heater region is set to be smaller than a heat value of the first heater region or the second heater region. A heater,
A heat conducting member arranged in contact with the heater, for uniformizing the temperature distribution of the heater,
A flexible sleeve rotatably provided and sliding on the heater;
A pressure member that forms the nip with the heater via the flexible sleeve;
Has,
An image heating apparatus for nipping, conveying, and heating a recording material on which a developer image is formed, between the flexible sleeve and the pressing member in the nip portion,
A plurality of the heat conducting members are arranged with a gap along a longitudinal direction of the nip portion,
The heater includes:
A third heater region that is a region of the heater corresponding to a gap between adjacent heat conductive members of the plurality of heat conductive members;
A contact area that is an area of the heater with which the heat conductive member contacts,
Is provided,
The difference between the temperature of the nip area heated in the contact area and the temperature of the nip area heated in the third heater area is zero, or the calorific value of the contact area, In order to be smaller than when assuming that the heat value of the third heater area is the same,
The image heating apparatus according to claim 1, wherein a heat value of the third heater region is set to be smaller than a heat value of the contact region. The heater has a substrate and a heating element formed on the substrate so as to extend in a longitudinal direction of the nip portion,
In a direction perpendicular to the longitudinal direction of the heating element, the width of the heating element in the third heater area is formed to be wider than the width of the heating element in the contact area, so that the amount of heat generated in the third heater area The image heating apparatus according to claim 9, wherein is set smaller than a heat value of the contact area. The heater has a substrate and a heating element formed on the substrate,
The image heating apparatus according to claim 1, wherein a thermal conductivity of the heat conductive member is higher than a thermal conductivity of the substrate. The heater has a substrate and a heating element formed on the substrate,
12. The heat conductive member according to claim 1, wherein the heat conductive member is arranged so as to contact a surface of the substrate opposite to a surface on which the heating element is formed. The image heating device according to claim 1.

Images