JP2019144286A - Image heating device and heating member - Google Patents

Abstract

To provide a means for suppressing a distortion of a heating member to maintain the adhesion between an inner surface of the belt by uniformly heating the belt without providing an auxiliary heating portion in an image heating device.SOLUTION: The device includes an endless belt, a rotating body for forming a nip portion for heating an image on the recording material in cooperation with the belt, a support member provided extending in a longitudinal direction of the belt inside the belt, a sheet-shaped heating member provided inside the belt, and is equipped with a fixed region fixed to the support member located at one end with respect to the rotational direction of the belt, a heating region for heating the belt in contact with the inner surface of the belt along the circumferential direction in a region different from the region for forming a nip portion with respect to the circumferential direction of the belt, and a heating member having an intermediate region between the fixed region and the heating region with respect to the circumferential direction.SELECTED DRAWING: Figure 1

Description

  The present invention relates to, for example, an image heating apparatus suitable for use as a fixing device mounted on an image forming apparatus such as a copying machine, a printer, a facsimile machine, and a multi-function machine having a plurality of these functions employing an electrophotographic system, and an image The present invention relates to a heating member used in a heating device.

  In Patent Document 1, a part is fixed so as to be in close contact with an inner peripheral surface (inner surface) of a rotatable endless heating belt (belt member) that heats an image on a recording material, and is free to contact the heating belt. A fixing device including a planar heating member having a heat generating portion in an end contact region is disclosed. The problem of this Patent Document 1 is that since the amount of expansion in the longitudinal direction is different between the portion where the heat generating layer of the heating member is present, that is, the portion contacting the heating belt and the portion where there is no heat generating layer between the support members, It was distorted and the adhesion to the heating belt was lost. And in patent document 1, it is going to solve this subject by providing an auxiliary heat generating part in the part which does not have a heat generating layer originally.

Japanese Patent Laid-Open No. 2006-180825

  However, although it is 75 W (Patent Document 1: Paragraph 0074), it is not preferable from the viewpoint of energy saving that the auxiliary heat generating unit consumes excess power.

  Therefore, an object of the present invention is to suppress the distortion of the heating member, maintain adhesion with the belt member, and uniformly heat the belt member without providing an auxiliary heat generating portion as in Patent Document 1.

In order to achieve the above object, a typical configuration of the image heating apparatus according to the present invention is as follows.
Endless belt,
In cooperation with the endless belt, a rotating body that forms a nip portion for heating an image on the recording material;
A support member provided extending in the longitudinal direction of the endless belt inside the endless belt;
A sheet-like heating member provided inside the endless belt, the fixing region being located on one end side with respect to the rotation direction of the endless belt and fixed to the support member, and the circumferential direction of the endless belt A heating region that heats the endless belt in contact with the inner surface of the endless belt along the circumferential direction in a region different from a region that forms the nip portion, and between the fixed region and the heating region with respect to the circumferential direction. An intermediate region, and a heating member having
The heating member has a recess on the one end side of the heating member,
The recess is provided in a region between the one end side and the intermediate region.

  According to the present invention, without providing an auxiliary heat generating portion, it is possible to suppress distortion of the heating member, maintain adhesion with the inner surface of the endless belt that heats the image, and uniformly heat the endless belt.

FIG. 2 is a developed plan view for explaining the heater according to the first embodiment (the figure best representing the features of the invention) Schematic diagram of the main part of an example of an image forming apparatus Schematic diagram of a transverse section of the main part of the fixing device of Example 1. Schematic diagram of the cross-section explaining the shape of the heater in the free state Schematic diagram of the cross section showing the layer structure of the heater

Example 1
(Printer part)
With reference to FIG. 2, an example of an image forming apparatus equipped with the image heating apparatus according to the present invention as the fixing device 16 (in this embodiment, a full color printer using an electrophotographic technique) will be described. The printer unit 50 that is an image forming unit that forms a toner image on the recording material S includes an image forming station that forms toner images of each color of yellow (Y), magenta (M), cyan (C), and black (K). Have.

  Each of the Y, M, C, and K stations has a drum-shaped electrophotographic photosensitive member 1 (Y, M, C, and K), a charging roller 2 (the same), an exposure device 3 (the same), as an image carrier. A developing unit 4 (same as above), a primary transfer roller 5 (same as above), and a drum cleaner 6 (same as above) are provided. Further, the printer unit 50 includes an endless belt (intermediate transfer belt) 17 that conveys a toner image transferred from the electrophotographic photosensitive member 1 of each station by the primary transfer roller 5, and the belt 17 to the recording material S. And a secondary transfer roller 18 for transferring the toner image. Reference numeral 10 denotes a belt cleaner, and 19 denotes a secondary transfer counter roller.

  Since the above-described image forming operation of the printer unit 50 is well known, detailed description thereof is omitted. The recording material S stored in the recording material cassette 20 is separated and fed by the rotation of the feeding roller 21, and introduced into the secondary transfer nip portion formed by the belt 17 and the secondary transfer roller 18 by the conveyance path 22. And nipped and conveyed. The recording material S on which the toner image T has been transferred from the belt 17 at the secondary transfer nip portion is sent to a fixing device (image heating device) 16 constituting the fixing portion. The toner image T is fixed by being heated and pressed as a fixed image on the recording material by the fixing device 16. Then, the recording material S on which the toner image is fixed is output (printed out) as a product.

(Heating device)
The schematic configuration of the fixing device (image heating device) 16 of this embodiment will be described with reference to FIG. The fixing device 16 is roughly divided into a heating unit 25 having a heating belt 14 as a rotatable endless belt member for heating an image on a recording material, an elastic pressure roller 15 as a nip forming member, An apparatus frame (apparatus housing) 30 that accommodates these is included. A nip portion (heating nip, fixing nip) N is formed by the cooperation of the heating belt 14 and the pressure roller 15 as a pair of rotating bodies. The nip portion N is a portion where the recording material S carrying an unfixed toner image T is nipped and conveyed to fix the toner image T with heat and pressure.

  Here, in the following description, the front side and the back side of the fixing device 16 or its constituent members are one end side and the other end side in the longitudinal direction, and in FIG. 2 or FIG. The side and the back side are the other end side.

(1) Heating unit In the present embodiment, the heating unit 25 includes a heating belt (endless belt) 14 and elasticity as a pressure pad 39, a stay 40, and a heating member disposed inside the heating belt 14. The assembly includes a sheet-like heater 51 and the like.

1) Heating belt In this embodiment, the endless heating belt 14 is a thin-walled hollow heat transfer member having heat resistance and flexibility, and is substantially cylindrical (tubular, hollow) due to its own elasticity in a free state. Body).

  The heating belt 14 is made of heat-resistant resin such as polyimide, polyamideimide, PEEK (polyetheretherketone), SUS (stainless steel) having high heat resistance and high thermal conductivity, pure metal such as Al, Ni, Cu, Zn, Alternatively, an alloy is used as a base layer. In the case of a resin base layer, in order to improve thermal conductivity, high thermal conductive powder such as BN, alumina, Al, etc. may be mixed. Furthermore, in order to prevent toner offset and ensure separation of the recording material, the surface layer is coated with a heat-resistant resin having a good releasability such as the following fluorine resin or silicone resin, or mixed or singly. A release layer is formed.

・ PTFE (polytetrafluoroethylene)
・ PFA (tetrafluoroethylene / perfluoroalkyl vinyl ether copolymer)
・ FEP (tetrafluoroethylene hexafluoropropylene copolymer)
・ ETFE (ethylene tetrafluoroethylene copolymer)
・ CTFE (Polychlorotrifluoroethylene)
・ PVDF (polyvinylidene fluoride), etc.

  In this embodiment, the release layer uses PFA. As a coating method, the outer surface of the belt base layer (or an intermediate material layer laminated thereon: the same applies hereinafter) may be etched and then the release layer may be dipped or applied by powder spraying or the like. Or the system which covers the resin formed in the tube shape on the surface of a belt base layer may be sufficient. Or after blasting the outer surface of a belt base layer, the primer layer which is an adhesive agent is apply | coated and the method of coat | covering the mold release layer previously shape | molded by the tube shape may be sufficient.

  The heating belt 14 in this embodiment has a three-layer structure of a base layer, an intermediate layer, and a release layer in order from the inside to the outside. The base layer is a polyimide having a thickness of 80 μm and an inner diameter of 30 mm. As an intermediate layer, silicone rubber is stacked on the outer peripheral surface of the base layer with a thickness of 200 μm, and further, a PFA tube having a thickness of 30 μm is stacked on the outer peripheral surface as a release layer. Yes.

2) Pressure pad The pressure pad 39 is a sliding contact member (a backup member, a pressing member) that is in sliding contact with (in contact with) the inner surface of the heating belt 14, and is elongated along the longitudinal direction (width direction) of the heating belt 14. It is a thin plate heat-resistant and heat-insulating member.

3) Stay The stay (support member) 40 is a rigid member that is long in the longitudinal direction (width direction) of the heating belt 14 and receives a reaction force from the pressure roller 15 and is not easily bent even when a high pressure is applied. It is preferable that In this embodiment, the stay 40 is made of SUM (sulfur and sulfur composite free-cutting steel), has a thickness of 1 mm, and is bent at two locations in the cross section of FIG. The pressure pad 39 is fixed to the lower surface of the stay 40 along the length, and the lower surface of the pressure pad 39 is configured to be slidable with the inner surface of the heating belt 14.

4) Heater The sheet-like heater 51 as a heating member is a heat source that contacts the inner surface of the heating belt 14 in a surface shape and heats the heating belt 14. The sheet-like heater 51 is fixed to the stay (support member) 40 on the inner side of the heating belt 14 with the upstream end side as a fixed end side in the rotation direction R14 of the heating belt 14. The heating belt 14 is brought into contact with the inner surface of the heating belt 14 in a region in the downstream end side (free end side not fixed) to heat the heating belt 14. The width of the sheet-like heater 51 substantially corresponds to the width of the heating belt 14. The characteristic configuration of the heater 51 will be described later.

  The heating belt 14 is loosely fitted (extrapolated) to the assembly of the pressure pad 39, the stay 40, and the heater 51 described above. The stay 40 is located inside the heating belt 14 and extends in the longitudinal direction of the heating belt 14, and the front side and the back side of the stay 40 are respectively opened from the front side and back side openings of the heating belt 14. It protrudes outward.

(Pressure roller)
The pressure roller 15 is made of an elastic solid rubber layer, an elastic sponge rubber layer, an elastic foam rubber layer, or the like on the outside of a metal core 37 such as SUS, SUM (sulfur and sulfur composite free-cutting steel), Al or the like. This is an elastic roller composed of the layer 38.

  Here, the elastic solid rubber layer is formed of heat-resistant rubber such as silicone rubber or fluorine rubber. The elastic sponge rubber layer is formed by foaming silicone rubber in order to have a more heat insulating effect. The elastic foam rubber layer is a 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. A release layer such as PFA resin or PTFE resin may be formed thereon.

  The pressure roller 15 in this embodiment uses SUS as the core metal 37 and an elastic solid silicone rubber layer as the elastic layer 38, and has an outer diameter of 25 mm.

  In the pressure roller 15, the front side and back side portions of the core metal 37 are rotatably supported between the front side and back side plates (not shown) of the apparatus frame 30 via bearings (not shown). . The heating unit 25 is arranged substantially parallel to the pressure roller 15 with the pressure pad 39 facing the pressure roller 15 between the front and back side plates of the apparatus frame 30.

  And the above-mentioned protrusion part of the near side and the back side of the stay 40 is urged | biased by the predetermined pressure in the direction of the pressure roller 15 by the pressurization mechanism (not shown), respectively. As a result, the lower surface of the pressure pad 39 is pressed against the elastic layer of the pressure roller 15 via the heating belt 14 with a predetermined pressing force, and the recording material S is interposed between the heating belt 14 and the pressure roller 15. A nip portion N having a predetermined width necessary for image heating is formed with respect to the transport direction X.

(Fixing operation)
The heating belt 14 is provided with driving gears (not shown) on the front side and the back side, respectively, and is directly driven by driving means (driving motor) M controlled by the control unit 100, and in the clockwise direction of the arrow R14 in FIG. It is rotationally driven at a predetermined peripheral speed (process speed). Along with the rotation of the heating belt 14, the pressure roller 15 is driven to rotate in the counterclockwise direction of the arrow R15 by the frictional force with the heating belt 14 in the nip portion N.

  On the other hand, the heater 51 generates heat when electric power is supplied from the power supply unit 101 controlled by the control unit 100 to the heater 51 via a power supply path (not shown). The heater 51 is in planar contact with the inner surface of the heating belt 14, and the rotating heating belt 14 is heated from the inside by the heat generated by the heater 51.

  Then, the outer surface temperature of the heater 51 is detected by temperature detection means (such as a thermistor) TH, and information on the detected temperature is fed back to the control unit 100. Based on information on the temperature of the heating belt 14 detected by the temperature detection means TH, the control unit 100 sends the temperature of the heating belt 14 from the power supply unit 101 to the heater 51 so as to be maintained at a predetermined target temperature. To control the power supply.

  In the above fixing device state, the recording material S carrying the unfixed toner image T is introduced from the printer unit 50 into the fixing device 16 and is nipped and conveyed by the nip portion N. The heat of the heating belt 14 is applied to the recording material S in the process of being nipped and conveyed by the nip portion N. The unfixed toner image T is melted by the heat of the heating belt 14 and is fixed to the recording material S by the pressure applied to the nip portion N.

(Heating heater)
The elastic sheet-like heater 51 is substantially fixed to the stay 40 with the upstream end in the rotation direction R14 of the heating belt 14 as a fixed end inside the heating belt 14. When the heater 51 is in a free state, that is, without the heating belt 14, as shown in FIG. 4, the heater 51 spreads more outward than the contour line (virtual line) 14 a indicating the heating belt 14. That is, it has a shape that spreads outward from the outer shape of the heating belt 14 due to its own elasticity.

  As shown in FIG. 3, the heater 51 is substantially fixed to the stay 40 with the upstream end when the heater 51 is viewed along the rotation direction R <b> 14 of the heating belt 14 as the fixed end inside the heating belt 14. It is arranged against its own elasticity. In this state, the heater 51 is regulated by the inner peripheral surface of the heating belt 14 in the free state of FIG. 4 against its own elasticity, and in the region on the downstream end side (the unfixed free end side). It contacts the inner surface of the heating belt 14 elastically in a planar shape.

  The upstream end side (fixed end side) of the heater 51 is bent at the portion indicated by C in FIGS. 1, 3, and 4, and the portion directly above (fixed region) is related to the stay 40. Are combined.

  FIG. 5 is a schematic cross-sectional view showing the layer structure in the thickness direction of the heater 51 in this embodiment, and the direction of the viewpoint is the same as in FIGS. 3 and 4.

  In FIG. 5, the upper layer of the heater 51 is a heat conductive layer 52 having elasticity, which is made of SUS and has a thickness of 30 μm. As the material, in addition to SUS, pure metals such as Al, Ni, Cu, Zn, or alloys can be used. The upper surface of the heat conductive layer 52 is in contact with the inner surface of the heating belt 14 and transmits heat from a heating element 54 described later to the heating belt 14.

  An insulating layer 53 made of polyimide having a thickness of 25 μm is in contact with the heat conductive layer 52. Below the insulating layer 53 is a heating element (heating part: heating resistor layer that generates heat when energized) of SUS having a thickness of 30 μm, and a thickness of 25 μm for sandwiching the heating element 54 together with the insulating layer 53. An insulating layer 55 made of polyimide is provided. Further, an elastic support layer 56 made of SUS having a thickness of 30 μm is disposed to contact the lower surface of the insulating layer 55 and support the entire heater 51. The material of the support layer 56 can also be a pure metal such as Al, Ni, Cu, Zn, or an alloy.

  The region where the heating element 54 exists (heating region) is the range of the region A in FIGS. This range A is a range in which the heater 51 is in contact with the heating belt 14, and heat from the heating element 54 is transmitted to the heating belt 14 through this range. The region A of the heater 51 is in contact with the inner surface of the heating belt 14 in a region different from the region where the nip portion N is formed in the circumferential direction of the heating belt 14.

  A region B in FIGS. 1 and 3 is an intermediate region upstream of the region A (heating region) with respect to the moving direction (rotation direction) of the heating belt 14 and downstream of the fixed end (fixed region). In this region B, the heating element 54 does not exist, and in the region B, the heater 51 generally does not contact the heating belt 14. In the region B, the heating element 54 may be present in the vicinity of the boundary of the region A. In this case, groove portions (recesses) 66 and 62 to be described later are provided in the region B without the heating element 54. Shall be provided.

  1A and 1B are views in which the heater 51 is developed in a plane. FIG. 1A is a view as seen from the heat conductive layer 52 side, and FIG. 1B is a view as seen from the support layer 56 side. In the present embodiment, the length (width dimension) L of the heater 51 in the vertical direction of FIG. 1 is 330 mm in a 25 ° C. environment. In addition, there is a power feeding unit (not shown) on the upper and lower portions (front side and back side) of the heater 51 in FIG. 1, and supplies power to the heating element 54.

(Heat heater groove)
On the upstream end side (fixed end side) of the support layer 56, as shown in FIG. 1B, at least one groove 66 (the first portion that crosses the heater 51 in the longitudinal direction of the heating belt 14) Are provided along the rotation direction R <b> 14 of the heating belt 14. A plurality of groove portions 66 can be formed at intervals. In this embodiment, two groove portions 66 are formed.

  The groove 66 is provided from the fixed end portion (fixed region) to the middle of the region B (intermediate region) across the bending portion C when viewed along the rotation direction of the heating belt 14. That is, the groove 66 is provided at a position where the edge of the groove 66 does not contact the heating belt 14. If no heating element is present in the region B, the groove 66 may be provided up to the boundary between the region B and the region A.

  It is more preferable that the groove portions 66 are provided so that the widths of the regions B divided by the groove portions 66 are not greatly different with respect to the longitudinal direction of the heating belt 14 (the width direction of the endless belt).

  Further, it is more preferable that the groove 66 is provided in a region corresponding to the maximum contact region in the longitudinal direction of the heating belt 14. The maximum contact area is an area of the heating belt 14 that can contact a recording material having a maximum size in the width direction among the recording materials that can be heated by the heating belt 14 in the longitudinal direction of the heating belt 14.

  Further, the groove 66 is more preferably 0.5 mm to 5.0 mm in width in the longitudinal direction of the heating belt 14 and 5.0 mm to 15.0 mm in depth along the circumferential direction of the heating belt 14. .

  On the upstream end side (fixed end side) of the heat conductive layer 52, as shown in FIG. 1A, at least one groove portion 62 (a first cross section across the heater 51 in the longitudinal direction of the heating belt 14) 2 incisions and recesses) are provided along the rotation direction R14 of the heating belt 14. A plurality of groove portions 62 can be formed at intervals. In this embodiment, two groove portions 62 are formed.

  The groove portion 62 is provided from the fixed end portion to the middle of the region B across the bending portion C when viewed along the rotation direction of the heating belt 14. That is, the groove 62 is provided at a position where the edge of the groove 62 does not contact the heating belt 14. If no heating element is present in the region B, the groove 62 may be provided up to the boundary between the region B and the region A.

  Here, it is more preferable that the groove portion 62 is provided so that the widths of the regions B divided by the groove portion 62 are not greatly different with respect to the longitudinal direction of the heating belt 14.

  Further, it is more preferable that the groove 62 is provided in a region corresponding to the maximum contact region with respect to the longitudinal direction of the heating belt 14. The maximum contact area is an area of the heating belt 14 that can contact a recording material having a maximum size in the width direction among the recording materials that can be heated by the heating belt 14 in the longitudinal direction of the heating belt 14.

  Further, the groove 62 is more preferably set to have a width in the longitudinal direction of the heating belt 14 of 0.5 mm or more and 5.0 mm or less and a depth along the circumferential direction of the heating belt 14 of 5.0 mm or more and 15.0 mm or less. .

Since the linear expansion coefficient of the heat conductive layer 52 and the support layer 56 is approximately 17 × 10 ⁻⁶ / ° C. in the region of 0 ° C. to 300 ° C., for example, when the heat conductive layer 52 reaches 200 ° C., the heater 51 The length L in the region A is 330.98 mm.

  For example, consider an image forming operation after the power of the image forming apparatus has been turned off and the stay 40 has become familiar with normal temperature (for example, 25 ° C.). Since the heat of the heating element 54 is first transmitted to the heating belt 14 side and is transmitted to the stay 40 with a delay, it is substantially supported by the region B of the heater 51 in FIG. 3, that is, the stay 40 and is still in contact with the heating belt 14. The temperature of the part which is not performed becomes lower than the temperature of the area | region A.

  Here, as a comparative example, consider a case where the grooves 62 and 66 are not formed in the heater 51. For example, when the area A reaches 200 ° C., but the area B is still 100 ° C., the length L of the heating belt 14 in the area B remains at 330.42 mm. As described above, the difference in longitudinal length between the region A and the region B causes distortion of the heat conductive layer 52 and the support layer 56 of the heater 51, and the adhesion between the heater 51 and the heating belt 14 in the region A. Sex is inhibited.

  In the configuration of the present embodiment, such a problem can be solved without providing auxiliary heating means as in Patent Document 1. That is, by forming the grooves 62 and 66 in the region B of the heat conductive layer 52 and the support layer 56, the length of the heater 51 in the low temperature state becomes the length of the heater in the region A. It becomes like. And the adhesiveness of the heater 51 and the heating belt 14 in the area A is improved, and the heating belt 14 can be heated uniformly.

  The method of fixing the heater 51 to the stay 40 may be devised within a range that does not hinder the gist of the present invention. For example, when the temperature of the region A is always adjusted at 200 ° C., the length L in the region B may be adjusted to be 330.98 mm in the room temperature state. In this embodiment, the heater 51 is bent at the position C shown in FIGS. 1, 3, and 4 and fixed to the stay 40 with three screws 57.

  Here, as shown in FIG. 1, the screw holes 72 and 76 on the heater 51 side are elongated holes extending in the longitudinal direction of the heater 51, and from the diameter (3.5 mm) of the foot of the screw 57. Is also 2 mm longer (5.5 mm). By this treatment, the length in the longitudinal direction of the fixed end side of the heater 51 can be made to follow the length in the longitudinal direction of the region A, and the effect of the present invention can be exhibited better. It is also preferable that the screw 57 is a step screw.

  Further, the shape of the grooves 62 and 66 may be V-shaped or rectangular. More preferably, it has a curved portion such as a U shape or a circular shape as in this embodiment. That is, it is preferable that the grooves 62 and 66 have a curved shape in a direction in which the edge approaches the region A (the range in which the heater 51 contacts the heating belt 14).

  Here, the edges of the grooves 62 and 66 are the portions of the fixed end of the heater 51 that are recessed from the edge toward the region A with reference to the edge extending along the longitudinal direction of the heating belt 14. Point to the edge.

  In this embodiment, as an example of a more preferable shape, as shown in FIG. 1, the shape on the back side (the side away from the fixed end) of the groove portions 66 and 62 is circular. Thereby, the possibility of breakage of the heat conductive layer 52 and the support layer 56 can be minimized. That is, since the downstream shape of the heating belt 14 in the rotation direction R14 has a curved shape, the possibility of breakage of the heat conductive layer 52 and the support layer 56 is extremely low. Thus, in order to suppress breakage of the heat conductive layer 52 and the support layer 56, it is preferable that the grooves 62 and 66 do not have a sharp shape toward the downstream side in the rotation direction of the heating belt 14.

  In this embodiment, the grooves 62 and 66 are formed so as to overlap each other when viewed from the direction perpendicular to the surface, but it is not necessary to do so. That is, the grooves 62 and 66 may be formed so as not to overlap with each other. In this case, the fixed end side of the heater 51 is fixed to the stay 40 in a region where the groove 62 and the groove 66 are not provided.

  Further, in this embodiment, the screw 57 is arranged one by one in each of the regions sandwiched between the groove 62, the groove 66, and both ends in the longitudinal direction of the support portion of the heater 51. It is not limited to this mode. For example, a plurality of screws 57 may be assigned to these areas. Moreover, even if there exists a location which is not engaged, the whole heater 51 should just be supported appropriately.

Example 2
The second embodiment is different from the first embodiment in the following points. That is, the heating belt 14 in Example 2 has a four-layer structure, and the base material is a nickel alloy having a thickness of 40 μm and an inner diameter of 30 mm, and has a 10 μm polyimide layer on the inner surface. Further, as an intermediate layer, a silicone rubber is stacked on the outer peripheral surface of the nickel layer with a thickness of 200 μm, and a PFA tube with a thickness of 30 μm is stacked on the outer peripheral surface as a release layer.

Further, in the second embodiment, in the heater 51, a copper plate having a thickness of 30 μm is used as the heat conductive layer 52, and the heat conductivity is increased so that the temperature of the heating belt 14 can be quickly increased. The linear expansion coefficient of copper is approximately 18 × 10 ⁻⁶ / ° C. in the region of 0 ° C. to 300 ° C., which is close to SUS. Of course, even the combination of the heat conductive layer 52 and the support layer 56 having different linear expansion coefficients can sufficiently exhibit the effects of the present invention.

《Other matters》
(1) The rotatable endless belt member 14 for heating the image on the recording material can be configured to be driven and rotated by the pressure roller 15 being rotationally driven as a driving rotary member. In addition, the endless belt member 14 having flexibility is suspended between two or more support members, and is rotated by a rotation mechanism including the pressure roller 15 or a rotation mechanism other than that. There may be.

  (2) The image heating apparatus according to the present invention is not limited to use as a fixing apparatus that heat-fixes an unfixed image as a fixed image on a recording material as in the embodiment. It can also be effectively used as a heating device that presupposes an unfixed image on a recording material, or a heating device that reheats a recording material carrying an image to improve image surface properties such as gloss.

  (3) The printer unit (image forming unit) 50 is not limited to the electrophotographic system. The image forming unit may be an electrostatic recording system or a magnetic recording system. Further, the toner image is not limited to the transfer method, and a toner image may be formed directly on the recording material.

  16 .. Image heating device (fixing device), 14.. Belt member (heating belt), R 14... Rotating direction of belt member, 51 .. Sheet-like heating member (heater heater), 66. 1st and 2nd notch)

Claims (14)

Endless belt,
In cooperation with the endless belt, a rotating body that forms a nip portion for heating an image on the recording material;
A support member provided extending in the longitudinal direction of the endless belt inside the endless belt;
A sheet-like heating member provided inside the endless belt, the fixing region being located on one end side with respect to the rotation direction of the endless belt and fixed to the support member, and the circumferential direction of the endless belt A heating region that heats the endless belt in contact with the inner surface of the endless belt along the circumferential direction in a region different from a region that forms the nip portion, and between the fixed region and the heating region with respect to the circumferential direction. An intermediate region, and a heating member having
Have
The heating member has a recess on the one end side of the heating member,
The image heating apparatus, wherein the recess is provided in a region from the one end side to the intermediate region.   The image heating apparatus according to claim 1, wherein the heating member is provided with a heat generating portion in the heating region. The heat generating part is also provided in the intermediate region,
The image heating apparatus according to claim 2, wherein the concave portion is provided in a region that does not overlap the heat generating portion.   The image heating apparatus according to claim 1, wherein the concave portion is provided at a position where an edge of the concave portion does not contact the endless belt.   The image heating apparatus according to claim 1, wherein the concave portion has a curved shape in a direction in which an edge of the concave portion approaches the heating region. Regarding the width direction of the endless belt, when the region of the endless belt that can be in contact with the recording material having the largest size in the width direction among the recording materials that can be heated by the endless belt is a maximum contact region,
The image heating apparatus according to claim 1, wherein the concave portion is provided in a region corresponding to the maximum contact region with respect to the position in the width direction.   The image heating apparatus according to claim 1, wherein the heating member is in contact with an inner surface of the endless belt by elasticity of the heating member. The heating member includes a heat generating portion for heating the endless belt, and a layer that supports the heat generating portion, and the heat generating portion is disposed between the endless belt and the heat generating portion is disposed on the inner surface of the endless belt. And a support layer that urges toward
The image heating apparatus according to claim 2, wherein the concave portion is provided in the support layer. The heating member includes a heat generating part for heating the endless belt, and a heat conductive layer that contacts the inner surface of the endless belt and transmits heat generated by the heat generating part to the endless belt,
The image heating apparatus according to claim 2, wherein the recess is provided in the heat conductive layer. Used in an image heating apparatus comprising: a rotatable endless belt for heating an image on a recording material; and a support member provided inside the endless belt and extending in the longitudinal direction of the endless belt. A sheet-like heating member,
A fixing region for fixing to the support member;
A heating layer, and a support layer that supports the heating unit and biases the heating unit toward the inner surface of the endless belt to sandwich the heating unit between the endless belt and the heating layer. A heating region that heats the endless belt in contact with the inner surface of the endless belt along the circumferential direction of the endless belt;
An intermediate region between the fixed region and the heating region with respect to the circumferential direction;
A concave portion provided at one end side of the heating member with respect to the circumferential direction and at an end portion on the fixed region side;
The heating member, wherein the recess is provided in a region from the one end side to the intermediate region. The heat generating part is also provided in the intermediate region,
The heating member according to claim 10, wherein the concave portion is provided in a region that does not overlap the heat generating portion.   The heating member according to claim 10, wherein the recess has a curved shape in a direction in which an edge of the recess approaches the heating region.   The heating member according to claim 10, wherein the recess is provided in the support layer. The heating member includes a heat conductive layer that contacts an inner surface of the endless belt and transmits heat generated by the heat generating portion to the endless belt,
The heating member according to claim 10, wherein the recess is provided in the heat conductive layer.