JP6242471B2 - Image heating device - Google Patents

Description

  The present invention relates to an image heating apparatus suitable for use as a fixing device provided in an electrophotographic image forming apparatus such as a copying machine or a printer.

  As a fixing device provided in an electrophotographic image forming apparatus, there is a film fixing type fixing device. The fixing device includes a film, a heating body that contacts the film, and a backup member that forms a nip portion together with the heating body via the film, and conveys a recording material carrying a toner image at the nip portion. In general, the toner image is heated.

  As the heating body, a ceramic heater in which a heating resistor is formed on a substrate made of a ceramic such as alumina or aluminum nitride is generally used.

  In such a film heating type fixing device that intensively heats the nip, the temperature of the non-sheet passing area of the heater through which the paper does not pass is higher than the temperature of the heater through which the paper passes. The temperature of the paper passing section is likely to increase. There is a problem that the substrate of the heater may break due to thermal stress due to a temperature difference between the sheet passing area and the non-sheet passing area due to the temperature increase in the non-sheet passing portion.

  Therefore, Patent Document 1 discloses a configuration in which a heat conduction member is provided between the heater and the heater support member in order to facilitate the movement of heat in the heater surface and make the temperature distribution in the longitudinal direction of the heater uniform. Yes.

JP-A-11-84919

  However, since patent document 1 is a structure by which a heat conductive member is fixed with respect to a support member with an adhesive agent, a heat conductive member tends to peel from a support member. This is because, when the heat conducting member and the support member are thermally expanded and contracted due to repeated heating and stopping of the fixing device, a shearing force due to the difference in linear expansion coefficient between them may act between them. The peeled heat conducting member is in an unstable state that is only sandwiched between the heater and the support member by the pressure of the nip portion. When an impact is applied to the fixing device for some reason, the position of the heat conducting member may be displaced with respect to the support member. As a result, the heat conducting member is displaced from an appropriate position with respect to the heater supported by the supporting member, and there is a problem that the effect of alleviating the temperature rise of the non-sheet passing portion is reduced.

  An object of the present invention is to provide an image heating apparatus in which the position of the heat conducting member is less likely to be displaced with respect to the heating body.

To achieve the above object, good optimal aspect of the onset Ming has a heating rotary member, a substrate, a heating resistor formed on said substrate, the length in contact with the heating rotating body A heat-conducting member having a long and thin shape in the longitudinal direction of the heater and having a thermal conductivity higher than that of the substrate, on the opposite side of the surface of the heater that contacts the heating rotor A heat conductive member that contacts the surface, and a support member that supports the heater via the heat conductive member, and heats the toner image on the recording material with the heat of the heater via the heating rotator. In the image heating apparatus, the heat conductive member has a locking portion at an end portion in a short direction of the heat conductive member, and the support member has a locked portion to which the locking portion is locked, by the locking portion is engaged with the engaged portion, pair to the support member of the heat conducting member Wherein the longitudinal position of the heat conducting member is configured to determined that.

  It is possible to provide an image heating apparatus in which the position of the heat conducting member is less likely to shift with respect to the heating body.

FIG. 6 is a schematic cross-sectional view illustrating the configuration of the fixing device according to the first embodiment. FIG. 5A is a schematic front view illustrating the configuration of the fixing device according to the first embodiment (when pressure is applied), and FIG. 5B is a schematic front view illustrating the configuration of the fixing device according to the first embodiment (when pressure is released). Explanatory drawing of the ceramic heater which concerns on Example 1. Explanatory drawing of the thermistor and thermal fuse concerning Example 1 (A) is a figure explaining the support method of the heater which concerns on Example 1, and a heat conductive member, (b) is the figure which did not display the electric power feeding connector and the heater clip in (a), (c) concerns on Example 1. The figure explaining the support method of a heat conductive member, (d) is a perspective view explaining the latching | locking part of the heat conductive member which concerns on Example 1. FIG. (A) is explanatory drawing of the electric power feeding connector which concerns on Example 1, (b) is explanatory drawing of the heater clip which concerns on Example 1. FIG. (A) is a partially enlarged view of the heater and the heat conducting member for explaining the heat flow in the heater, and (b) is an enlarged view of the end of the heater and the heat conducting member in the first embodiment. (A) is a figure explaining the support method of the heater and heat conductive member of a comparative example, (b) is a figure explaining the support method of the heat conductive member of a comparative example, (c) is a bending of the heat conductive member of a comparative example. Enlarged view of the section (A)-(d) is a figure explaining the deformation | transformation process of the heat conductive member of a comparative example. (A) is a figure explaining the heat flow of a heater longitudinal end part, (b) is a figure explaining the heat flow of a heater longitudinal end part. The figure explaining the deformation | transformation of a heat conductive member The perspective view explaining the latching | locking part of the heat conductive member which concerns on Example 2. FIG. (A) is a perspective view of the heat conductive member which concerns on the modification of Example 2, (b) is a perspective view of the heat conductive member which concerns on the modification of an Example. (A) is a figure explaining the heat conductive member which concerns on Example 3, (b) is a figure explaining engagement of the heat conductive member and support member which concern on Example 3.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

  In the following description of the apparatus configuration, the longitudinal direction is a direction parallel to the recording material conveyance surface and orthogonal to the recording material conveyance direction. The short side direction is a direction parallel to the recording material conveyance direction.

  FIG. 1 is a schematic cross-sectional view of a fixing device 18 according to the present embodiment, which is an image heating device to which the present invention is applied. FIG. 2 is a schematic view of an end portion of the fixing device 18 viewed from a short side. FIG.

  The fixing device 18 includes a cylindrical film 36, a heater 37 as a heating body that contacts the film 36, a support member 38 that supports the heater 37, and a backup 37 that forms the nip portion N together with the heater 37 through the film 36. And a pressure roller 32 as a member. The fixing device 36 heats the recording material carrying the toner image t at the nip portion N and heats the recording material to fix the toner image t to the recording material. The fixing device 18 further includes a heat conducting member 39 that is in contact with the surface of the heater 37 that is opposite to the surface that is in contact with the film 36 along the longitudinal direction of the heater 37. The support member 38 supports a part of the heater 37 through the heat conducting member 39.

  The film 36, the heater 37, the heat conducting member 39, the support member 38, the reinforcing stay 40 that reinforces the support member, and the flange 41 that restricts the displacement of the film 36 are unitized as a film unit 31. . The film unit 31 and the pressure roller 32 are disposed substantially in parallel between the left and right side plates 34 of the apparatus frame 33.

  The pressure roller 32 has a cored bar 32a, an elastic layer 32b formed outside the cored bar 32a, and a release layer 32c formed outside the elastic layer 32b. Silicone rubber, fluorine rubber, or the like is used as the material of the elastic layer 32b. As a material of the release layer 32c, PFA, PTFE, FEP or the like is used. PFA is a tetrafluoroethylene / perfluoroalkyl vinyl ether copolymer, PTFE is polytetrafluoroethylene, and FEP is a tetrafluoroethylene / hexafluoropropylene copolymer. In this example, stainless steel having an outer diameter of 11 mm was used as the core metal 32a, a silicone rubber layer having a thickness of about 3.5 mm was used as the elastic layer 32b, and a PFA tube was used as the release layer 32c. The outer diameter of the pressure roller 32 is 18 mm. The hardness of the pressure roller 32 is preferably in the range of 40 ° to 70 ° at a load of 9.8 N with an ASKER-C hardness meter from the viewpoint of securing an appropriate width of the nip portion N and durability. The hardness of the pressure roller 32 in this embodiment is 54 °. The length of the elastic layer of the pressure roller 32 in the direction orthogonal to the conveying direction of the recording material is 226 mm. As shown in FIG. 2, both ends of the pressure bar 32 in the longitudinal direction of the core metal 32 a are rotatably supported between the apparatus frame side plates 34 via bearing members 35. G is a drive gear fixed to one end of the cored bar 32a. A rotational force is transmitted to the drive gear G from a drive source (not shown), and the pressure roller 32 is rotationally driven.

  The film 36 is a flexible member having a base layer, an elastic layer formed outside the base layer, and a release layer formed outside the elastic layer. The film 36 of this example has an inner diameter of 18 mm, and uses a polyimide base material having a thickness of 60 μm as a base layer, silicone rubber having a thickness of about 150 μm as an elastic layer, and a PFA tube having a thickness of 15 μm as a release layer. As shown in FIG. 1, the support member 38 of the present embodiment is a member having a substantially semicircular saddle shape in cross section, and is formed of a liquid crystal polymer. The support member 38 has a role of supporting the inner surface of the film 36 fitted on the support member 38 and a role of supporting the surface of the heater 37 opposite to the surface in contact with the film 36.

  As shown in FIG. 3, the heater 37 has a heating resistor 37b made of silver / palladium alloy or the like formed on a long substrate 37a made of ceramics such as alumina or aluminum nitride by screen printing or the like. An electrical contact portion 37c made of silver or the like is connected to 37b. In the present embodiment, two heating resistors 37b are connected in series. A glass coat 37d is formed as a protective layer on the heat generating resistor to protect the heat generating resistor, and the slidability between the heater 37 and the film 36 is improved. The heater 37 is disposed along the generatrix direction of the film 36 while facing one surface of the support member 38. The substrate 37a of this embodiment has a rectangular parallelepiped shape with a width of 270 mm in the direction orthogonal to the recording material conveyance direction, a width of 5.8 mm in the recording material conveyance direction, and a thickness of 1.0 mm, and is formed of alumina. ing. The width of the heating resistor 37b in the conveyance direction of the recording material is 222 mm. Note that the slidability between the heater 37 and the support member 38 and the inner surface of the film 36 is improved by applying grease as a heat-resistant lubricant to the inner surface of the film 36.

  FIG. 4 is a view showing the support member 38, the thermistor 42 as a temperature sensitive element, and the temperature fuse 43 as a safety element. A through hole is provided in the support member 38, and the thermistor 42 and the thermal fuse 43 are arranged so as to contact the heat conducting member 39 from the through hole. That is, the thermistor 42 detects the temperature of the heater 37 through the heat conducting member 39, and the temperature fuse 43 senses the heat of the heater through the heat conducting member 39.

  The thermal fuse 43 is a component that senses abnormal heat generation of the heater when the heater 37 abnormally heats up and cuts off the power supply to the heater 37. The thermal fuse 43 is installed on the thermal conductive member 39 via thermal conductive grease, and prevents malfunction due to the thermal fuse 43 floating with respect to the heater 37.

  Next, the reinforcing stay 40 in FIG. 1 has a U-shaped cross section and is a member that is long in the generatrix direction of the film 36. The role of the reinforcing stay 40 is to increase the bending rigidity of the film unit 31. The reinforcing stay 40 of this embodiment is formed by bending stainless steel having a plate thickness of 1.6 mm.

  The left and right flanges 41 hold both ends of the reinforcing stay 40, and the vertical groove portions 41 a included in the left and right flanges 41 are engaged with the vertical groove portions 34 a included in the left and right side plates 34 of the apparatus frame 33. In this embodiment, a liquid crystal polymer is used as the material of the flange 41.

  As shown in FIG. 2, the pressure spring 45 is provided between the pressure portions 41 b of the left and right flanges 41 and the pressure arms 44. The heater 37 is pressed against the pressure roller 32 by sandwiching the film 36 through the left and right flanges 41, the reinforcing stay 40, and the support member 38 by the force of the pressure spring 45. As a result, the heater 37 forms a nip portion N of 6.2 mm together with the pressure roller 32 through the film 36. In this embodiment, the pressure contact force between the film 36 and the pressure roller 32 is 180 N in total pressure.

  During operation of the fixing device, a rotational force is transmitted from a drive source (not shown) to the drive gear G of the pressure roller 32, and the pressure roller 32 is rotationally driven clockwise at a predetermined speed in FIG. As the pressure roller 32 is driven to rotate, a rotational force acts on the film 36 by a frictional force acting between the pressure roller 32 and the film 36 in the nip portion N. As a result, as shown in FIG. 1, the film 36 slides while contacting one surface of the heater 37 and rotates around the outer periphery of the support member 38 in the counterclockwise direction following the rotation of the pressure roller 32.

  The film 36 rotates, the heater 37 is energized, and the recording material P is introduced into the nip portion N with the temperature detected by the thermistor 42 reaching the target temperature. The fixing entrance guide 30 plays a role of guiding the recording material P on which the toner image t in an unfixed state is placed toward the nip portion N between the film 36 and the pressure roller 32. The recording material P carrying the unfixed toner image t is conveyed in the nip portion N so that the unfixed toner image t contacts the film 36. In this conveyance process, the unfixed toner image t is fixed on the recording material P by the heat of the film 36 heated by the heater 37 and the pressure applied to the nip portion N. The recording material P that has passed through the nip portion N is discharged after being separated from the surface of the film 36 by a curvature, and is discharged outside the apparatus by a pair of discharge rollers (not shown). The maximum sheet passing width of the fixing device in this embodiment is 216 mm.

  Here, the pressure releasing operation by the pressure releasing mechanism of the fixing device 36 will be described. The pressure release mechanism rotates a pressure release cam (not shown) to move an arm (not shown). The flanges 41 on both sides are pushed by the movement of the arm and the film unit 31 is moved away from the pressure roller 32 to release or reduce the pressure applied to the nip portion N. FIG. 2A is a diagram showing the fixing device before the pressure is released, and FIG. 2B is a diagram showing the fixing device after the pressure is released. The purpose of this pressure release operation is to facilitate a process of removing the recording material P from the fixing device 18 when the jamming of the recording material occurs during the fixing process in the fixing device 18, so-called jam processing. The other purpose of the pressure release operation is to prevent the film 36 from being deformed by the pressure applied to the nip portion in the sleep mode in which the power supplied to the heater 37 is stopped to reduce the power consumption of the fixing device. In this embodiment, the fixing device automatically releases the pressure, but may be configured to release the pressure manually.

(Features of this embodiment)
The heat conductive member 39 of the present embodiment will be described with reference to FIG. The heat conducting member 39 of the present embodiment is formed of an aluminum plate. FIG. 5A is a cross-sectional view of an assembly in which the heat conducting member 39 and the heater 37 are assembled to the support member 38 as viewed from the short side direction. FIG. 5B is a view in which the power supply connector 46 and the heater clip 47 are not shown in FIG. FIG. 5C is a top view of the assembly in which the heat conducting member 39 is assembled to the support member 38. FIG. 5D is a perspective view of the support member 38 and the heat conducting member 39.

  In the present embodiment, as shown in FIG. 5A, a heater 37 is provided on the support member 38 via a heat conducting member 39. Both ends of the heater 37 in the direction orthogonal to the recording material conveyance direction are held by the support member 38 by a power supply connector 46 and a heater clip 47 as holding members, respectively. Further, the end of the heater 37 in the direction orthogonal to the recording material conveyance direction is in contact with a regulating surface (regulating portion) 49 of the support member 38 as shown in FIG. As shown in FIG. 5B, the central portion of the heater 37 is supported by the support member 38 via the heat conducting member 39 in the direction orthogonal to the conveyance direction of the recording material, and both end portions of the heater 37 are supported by the support member 38. Is supported by contact.

  As shown in FIG. 6A, the power supply connector 46 has a U-shaped housing portion 46a made of resin and contact terminals 46b. The power supply connector 46 has a role of holding the heater 37 and the support member 38 therebetween, and a role of energizing the heating resistor 37b by bringing the contact terminal 46b into contact with the electrode 37c of the heater 37 shown in FIG. Note that a member for supplying power to the heater 37 and a member for holding the heater 37 and the support member may be configured separately.

  The contact terminal 46 b is connected to an AC power source and a triac (not shown) via a bundle 48. As shown in FIG. 6B, the heater clip 47 is formed of a metal plate bent into a U-shape, and holds the state where the end of the heater 37 contacts the support member 38 due to its elasticity. . The heater 37 is restricted from moving in the thickness direction of the heater 37 with respect to the support member 38 by the heater clip 47. On the other hand, in the direction orthogonal to the conveyance direction of the recording material, the end of the heater 37 opposite to the end restricted by the restriction surface 49 of the support member 38 is not restricted by the support member 38. It is possible to absorb thermal expansion and contraction.

  With reference to FIG. 5D, the engaging portion of the heat conducting member 39, which is a feature of the present embodiment, will be described. In this embodiment, an aluminum plate having a thickness of 0.3 mm is used as the heat conducting member 39. The width L in the direction orthogonal to the recording material conveyance direction in the contact area where the heat conducting member 39 contacts the heater 37 is 222 mm, and the width M in the recording material conveyance direction is 5 mm. As shown in FIG. 5D, the heat conducting member 39 has a bent portion 39a as a locking portion at the center in the direction orthogonal to the recording material conveyance direction and at the end in the recording material conveyance direction. ing. The bending portion 39a has a width a of 8 mm in a direction perpendicular to the recording material conveyance direction, and a protruding amount b of the heat conducting member 39a from the surface facing the support member 38 to the side where the support member 38 is present is 3 mm. . The heat conducting member 39 is locked in a direction perpendicular to the recording material conveyance direction by inserting the bent portion 39a into a hole 38a as a locked portion provided in the support member. The hole 38a is formed to be slightly larger than the bent portion 39a in order to absorb the thermal expansion of the heat conducting member 39. In this embodiment, the hole 38a has a width c in the direction perpendicular to the recording material conveyance direction of 8.1 mm, a width d in the recording material conveyance direction of 0.4 mm, and the support member 38 of the heat conducting member 39. The play in the direction perpendicular to the recording material conveyance direction is 0.1 mm.

  The substrate 37a of this embodiment has a rectangular parallelepiped shape with a width of 270 mm in the direction perpendicular to the recording material conveyance direction, a width of 5.8 mm in the recording material conveyance direction, and a thickness of 1.0 mm, and is formed of alumina. . The length of the heating resistor 37 b in the direction perpendicular to the recording material conveyance direction is 222 mm, which is the same as the width of the contact area where the heat conducting member 39 contacts the heater 37.

(Operation of this embodiment)
A mechanism for equalizing the heat of the heater 37 in a direction orthogonal to the recording material conveyance direction in a situation where non-sheet-passing temperature rise occurs by continuously fixing small-size recording materials will be described.

  The thermal conductivity of alumina used as the substrate 37a in this embodiment is about 26 W / mK, and the thermal conductivity of aluminum used as the heat conductive member 39 is about 230 W / mK. When the thermal conductivity of the heat conducting member 39 is higher than that of the substrate 37a, the heat of the heater 37 can be easily made uniform. In addition to aluminum, copper or graphite sheet can be used as the material of the heat conducting member 39. As shown in FIG. 7A, the case where a portion H in the direction orthogonal to the recording material conveyance direction of the substrate 37a becomes higher than the other portions will be described. In addition to the heat flow A in the direction orthogonal to the recording material conveyance direction inside the substrate 37a, the heat flow from the substrate 37a to the heat conduction member 39 in the portion of the substrate 37a that is in contact with the heat conduction member 39. Occurs. Further, this heat flows in the direction perpendicular to the conveyance direction of the recording material inside the heat conducting member 39 and returns to the substrate 37a again. Such heat flow makes the heat of the heater 37 uniform.

  Here, the relationship between the width of the heating resistor 37b of the heater 37 and the width of the heat conducting member 39 in the direction orthogonal to the conveyance direction of the recording material will be described. FIG. 10 is an enlarged view of one end portion in a state where the positions of the heater 37 and the heat conducting member 39 are shifted in a direction perpendicular to the recording material conveyance direction. As shown in FIG. 10A, when the end portion of the heat conducting member 39 protrudes outward from the end portion of the heating resistor 37b, in addition to the heat flows A and B, Heat escape C due to heat radiation from the end of the conductive member 39 occurs. As a result, the temperature of the heater 37 is lowered more than necessary at the location H1, and fixing failure may occur at the location corresponding to H1 when the large size recording material is fixed. Further, as shown in FIG. 10B, when the end portion of the heating resistor 37b protrudes outward from the end portion of the heat conducting member 39, the heat conducting member 39 of the heating resistor 37b is moved to. The effect of suppressing the temperature rise of the non-sheet passing portion cannot be obtained at the location H2 where the heat flow cannot be formed.

  In view of the above situation, in the present embodiment, the width of the heating resistor 37b and the width of the heat conducting member 39 are made substantially the same in the direction orthogonal to the conveyance direction of the recording material. Further, as shown in FIG. 7B, the position of one end of the heating resistor 37b and the position of one end of the heat conducting member 39 are matched (broken line X). As a result, the fixing device 36 of the present embodiment can suppress the temperature rise of the non-sheet passing portion during the fixing process of the small size recording material without causing a fixing defect at the end during the fixing process of the large size recording material. Has an effect.

  Next, the reason why the bent portion 39a of the present embodiment is provided at the end of the heat conducting member 39 in the recording material conveyance direction will be described. As a comparative example of this embodiment, as shown in FIG. 8, a configuration in which L-shaped bent portions 390b are provided at both ends of the heat conducting member 390 in the direction orthogonal to the recording material conveyance direction is shown. As shown in the enlarged view of the bent portion 390b in FIG. 8C, the bent portion 390b is formed by bending the end portion of the heat conducting member 390 in a direction orthogonal to the recording material conveyance direction, and has a bending length Z Is 3 mm. FIG. 8A is a cross-sectional view as seen from the short side direction, and FIG. 8B is a view showing a state in which the heat conducting member 39 is provided on the support member 380. As the heat conducting member 390, an aluminum plate having a thickness of 0.3 mm is used, and the width L in the direction perpendicular to the recording material conveyance direction in the contact area in contact with the heater 37 is 222 mm. The portion where M is 5 mm has the same configuration as in this embodiment. In the configuration of the comparative example, the difference from the present embodiment is that the heat conducting member 390 has L-shaped bent portions 390b having a length of 3 mm at both ends in the direction orthogonal to the recording material conveyance direction. Reference numeral 390b denotes a portion inserted into the mounting holes 380b at both ends of the support member 380. Further, the mounting hole 380b is formed larger than the bent portion 390b of the heat conducting member 390 to provide play in order to absorb thermal expansion in a direction perpendicular to the recording material conveyance direction of the heat conducting member 390.

Here, the deformation amount ΔL (mm) in the direction orthogonal to the recording material conveyance direction due to the thermal expansion of the heat conducting member 390 can be calculated by the following equation.
ΔL = L × α × ΔT α: linear expansion coefficient, ΔT: temperature difference

  The heat conducting member 390 has a width L of 222 mm, an aluminum linear expansion coefficient α = 2.3 × 10 ^ −5 / ° C., and the temperature of the substrate 37a during the fixing process is about 200 ° C. ΔT = 180 ° C. When calculated by substituting into the above equation, ΔL is 0.92 mm. Similarly, the amount of deformation ΔM (mm) in the conveyance direction of the recording material of the heat conducting member 390 due to thermal expansion is 0.02 mm. On the other hand, the liquid crystal polymer (Sumika Super LCP E5204L manufactured by Sumitomo Chemical Co., Ltd.), which is the material of the support member 380, has a linear expansion coefficient α of 1.3 × 10 ^ −5 / ° C., and thus is perpendicular to the recording material conveyance direction. To 0.52 mm.

  In the fixing device of the comparative example, the following problem may occur due to the difference in the coefficient of linear expansion between the support member 380 and the heat conducting member 390. FIG. 9 is a cross-sectional view of the support member 380 and the heat conductive member 390 when the fixing device of the comparative example is used as viewed from the recording material conveyance direction. FIG. 9A shows a state in which a pressing force F of 180 N is applied to the nip portion. The heat conducting member 390 and the support member 380 are both thermally expanded and extend in a direction perpendicular to the recording material conveyance direction, but the amount of expansion of the heat conductive member 390 is larger than that of the support member 380 due to the difference in the linear expansion coefficient. FIG. 9B shows a state where the applied pressure is released by the pressure release mechanism. When the applied pressure at the nip portion is released, the heat conducting member 390 is easily moved on the support member 380. As a result, as shown in FIG. 9B, the heat conducting member 390 moves in the direction of the arrow (the direction orthogonal to the recording material conveyance direction), and the bent portion 390b of the heat conducting member 390 moves to the end face of the hole 380b. It may be in contact. Next, FIG. 9C shows a state where the heat conduction member 390 and the support member 380 are cooled in the process of cooling the fixing device after the pressure is applied again to the nip portion from the state of FIG. 9B and the fixing process is performed. The state when heat shrinks is shown. Since the amount of contraction of the heat conductive member 390 is larger than the amount of contraction of the support member 380, the heat conductive member 390 contracts while deforming the bent portion 390b in contact with the end surface of the hole 380b in the opening direction. Since the bent portion 390b of the comparative example is formed by bending the end portion of the heat conducting member 390 in a direction orthogonal to the recording material conveyance direction, it easily opens when receiving a force in a direction orthogonal to the recording material conveyance direction. . Since the states of FIGS. 9A to 9C are repeated when the fixing device is used, the bent portion 390b gradually opens as shown in FIG. 9D. Since the deformation of the heat conducting member 390 can occur at both ends, the bent portion 390b may be disengaged from the hole 380b of the support member 380. As a result, the heat conducting member 390 is not locked with respect to the support member 380 in the direction orthogonal to the recording material conveyance direction, and the position of the heat conducting member 390 may be displaced with respect to the heater 37. . If the position of the heat conducting member 390 is greatly deviated with respect to the heater 37, there arises a problem that the fixing failure at the end of the large size recording material and the temperature rise at the non-sheet passing portion cannot be suppressed.

  On the other hand, the heat conducting member 39 of the present embodiment has a bent portion 39a formed by bending an end portion in the recording material conveyance direction in a direction intersecting a direction orthogonal to the recording material conveyance direction. The heat conducting member 39 is locked to the support member 38 in a direction orthogonal to the recording material conveyance direction by inserting the bent portion 39a into the hole 38a of the support member 38. Further, the bent portion 39a is provided at substantially the center in the direction orthogonal to the recording material conveyance direction of the heat conducting member 39. Since the width a of the bent portion 39a in the present embodiment in the direction orthogonal to the recording material conveyance direction is 8 mm, the thermal expansion amount of the bending portion 39a in the direction orthogonal to the recording material conveyance direction is 0.03 mm. small. Therefore, since the play of the width | variety of the hole 38a can be made small with respect to the bending part 39a, the shift | offset | difference of the position of the heat conductive member 39 with respect to the supporting member 38 can be made small. Accordingly, since the position of the heater 37 in the direction orthogonal to the recording material conveyance direction is determined by the support member 38, the positional deviation of the heat conducting member 39 relative to the heater 37 can be reduced. As described above, in this embodiment, the width of the hole 38a is set to 8.1 mm. In addition, since the heat conducting member 39 is free at both ends in the direction orthogonal to the recording material conveyance direction, the bent portion 39a is not deformed by its own thermal expansion and contraction. Furthermore, the thermal expansion amount ΔM of the heat conducting member 39 in the recording material conveyance direction is 0.02 mm, and the bent portion 39a does not open greatly in the recording material conveyance direction as in the comparative example. Further, since the bent portion 39a is formed by bending in a direction intersecting the direction orthogonal to the recording material conveyance direction, even if a force in the recording material conveyance direction is applied, the bending portion 39a is deformed in the opening direction. do not do.

  As described above, in this embodiment, the heat conducting member 39 is maintained in a state of being locked with respect to the support member 38, so that there is an effect that the position is not easily displaced with respect to the heater 37. Thus, the temperature rise of the non-sheet passing portion can be suppressed without deteriorating the fixing property at the end portion in the direction perpendicular to the recording material conveyance direction.

  The heat conducting member 39 is also locked in the recording material conveyance direction with respect to the support member 38 by providing a bent portion 39a at the upstream end in the recording material conveyance direction and inserting it into the hole 38a. Yes.

  In this embodiment, the bent portion 39a is provided at the end of the heat conducting member 39 in the recording material conveyance direction, but it may be formed at the central portion of the heat conducting member 39 in the recording material conveyance direction. That is, a direction perpendicular to the conveyance direction of the recording material with respect to the support member, with a bent portion formed by bending a part of the heat conducting member itself in a direction intersecting the direction orthogonal to the conveyance direction of the recording material as a locking portion Any structure can be used as long as it can be locked to. However, if the bent portion 39a is formed by bending and raising the central portion of the heat conduction member 39 in the recording material conveyance direction, the heat conduction performance for making the heat of the heater 37 uniform due to a hole in the heat conduction member is reduced. It is better to use the locking part as a separate member.

  In recent years, in order to shorten the FPOT (First Print Out Time) of the image forming apparatus, it is required to shorten the warm-up time of the fixing device. Therefore, in this embodiment, a configuration when the heat capacity of the heat conducting member is further reduced will be described.

  The heat conducting member 391 of this embodiment has a smaller heat capacity by reducing the width and thickness of the recording material in the conveyance direction than that of the first embodiment. In this embodiment, an aluminum plate having a width of 3 mm in the conveyance direction of the recording material and a thickness of 0.2 mm is used as the heat conducting member 391. The heat capacity of the heat conducting member 391 is 40% of that of the heat conducting member 39 of the first embodiment, and the warm-up time can be shortened by 0.1 second. In the present embodiment, since the configuration other than the heat conducting member 391 and the support member 381 is the same as that of the first embodiment, description thereof is omitted.

  The characteristic configuration of the heat conducting member 391 of the present embodiment is a portion in which a plurality of locking portions are provided in a direction orthogonal to the recording material conveyance direction. When the heat conducting member 391 which is thin and has low rigidity is used as in the present embodiment, if the locking portion is at one place in the center as in the embodiment 1, the heat conducting member is made of a recording material as shown in FIG. There is a case where it is deformed into a bow shape in the conveying direction. The bow-like deformation of the heat conducting member occurs because the heat conducting member receives a force in the direction from the upstream to the downstream in the recording material conveyance direction via the heater 37 when the film 36 rotates. The substrate 37a is a ceramic having a thickness of 1.0 mm and has high rigidity and is difficult to be deformed. On the other hand, the heat conduction member that is a thin aluminum plate may be plastically deformed at a high temperature. When the heat conducting member is deformed, the position with respect to the heating resistor 37b is shifted, so that there is a problem that the effect of suppressing the temperature rise of the non-sheet passing portion is reduced.

  Therefore, in this embodiment, the heat conducting member 391 has a bent portion 391a (first locking portion) at the center portion and a bent portion 391c (second second portion) at one end in the direction orthogonal to the conveyance direction of the recording material. 391d (third locking portion) at the other end. By inserting these bent portions into holes 381a, 381c, and 381d as locked portions, the heat conducting member 391 is locked to the support member 381. The bent portion 391a plays a role as at least a locking portion in a direction orthogonal to the recording material conveyance direction, and the bending portions 391c and 391d are configured to play a role as at least a locking portion in the recording material conveyance direction. The sizes of the bent portion 391a and the hole 381a are a = 8 mm, b = 3 mm, c = 8.1 mm, and d = 0.3 mm, and the bent portions 391c and 391d and the holes 381c and 381d at the both ends are also the same size. . The width L in the direction perpendicular to the recording material conveyance direction of the contact area of the heat conducting member 391 that contacts the heater 37 is 222 mm, and the width M in the recording material conveyance direction is 3 mm.

  Note that the bent portions 391a, 391c, and 391d of the heat conducting member 391 need not have the same size. Further, the bent portions 391c and 391d may be provided at the end portion in the direction orthogonal to the recording material conveyance direction of the heat conducting member as shown in FIG. 13 (a), or as shown in FIG. 13 (b). You may provide in the edge part of the downstream of the conveyance direction of a recording material. In the configuration of FIG. 13A, the bent portion 391a plays a role as a locking portion in a direction perpendicular to the recording material conveyance direction, and the bending portions 391c and 391d function as a locking portion in the recording material conveyance direction. It is constituted so as to bear. Therefore, the configuration of FIG. 13A does not cause the problem that the bent portion at the end is opened unlike the comparative example of the first embodiment.

  As described above, the second embodiment has an effect that the position of the heat conducting member 391 is not easily displaced with respect to the heater 37 while reducing the heat capacity of the heat conducting member 391.

  As the length of the bent portion as the locking portion of the heat conducting member is longer, there is an advantage that the relationship between the heat conducting member and the support member is less likely to be released when the applied pressure at the nip portion is released. However, the longer the length of the bent portion, the greater the heat capacity of the heat conducting member, and more easily heat is released from the bent portion into the air, so the warm-up time of the fixing device is extended.

  Accordingly, there is a demand for a heat conducting member that has a shorter bent portion and is less likely to be disengaged from the support member.

  Therefore, the heat conducting member 392 of the present embodiment will be described with reference to FIG. The heat conducting member 392 includes a bent portion 392a (first locking portion) at the end in the recording material conveyance direction, and bent portions 392c (second locking portions) and 392d (third locking) at both ends. Part). The bent portions 392c and 392d are provided with holes 392e (engaging portions), and the holes engage with the claw portions 382e (engaging portions) of the support member 382. Since the configuration other than the heat conducting member 392 and the support member 382 is the same as that of the first embodiment, the description thereof is omitted.

  A further specific configuration of the heat conducting member 392 of the present embodiment will be described. The heat conducting member 392 is an aluminum plate having a width M in the conveyance direction of the recording material of 3 mm and a thickness of 0.2 mm. As in the first and second embodiments, the heat conducting member 392 has a bent portion 392a at the end in the recording material conveyance direction, and the bending portion 392a itself is orthogonal to the support member 382 in the recording material conveyance direction. Locked in the direction. In the third embodiment, the heat conducting member 392 further has bent portions 392c and 392d having a length b of 2 mm at the end in the direction perpendicular to the recording material conveyance direction, and each of them has a square shape of 1 mm × 1 mm. A through hole 392e is provided. On the other hand, as shown in FIG. 14B, a claw portion 382e is provided at the end of the support member 382 in the direction orthogonal to the recording material conveyance direction, and the claw portion 382e is engaged with the hole 392e of the heat conducting member 392. The configuration is matched.

  In the present configuration, when the pressure applied to the nip portion is released, even if the lengths b of the bent portions 392c and 392d are short, the heat conducting member 392 is in the direction of the arrow in FIG. It is hard to come off. Further, since both end portions of the heat conducting member 392 are engaged with the support member 382, the heat conducting member 392 is not easily deformed into an arc shape in the recording material conveyance direction.

  As described in the second embodiment, since the heat conducting member 392 has the bent portion 392a, the bent portions 392c and 392d do not open unlike the comparative example of the first embodiment.

  As described above, the fixing device of this embodiment can reduce the heat capacity of the heat conductive member 392 and reduce the warm-up time in addition to the effect that the heat conductive member 392 is not easily displaced with respect to the heater 37. Has the effect of contributing to

  In this embodiment, the holes 392e are provided in the bent portions 392c and 392d. However, the holes 392e may be provided in the bent portions 392a to be engaged with the support member 382. In that case, it is not always necessary to provide the hole 392e in the bent portions 392c and 392d and engage with the support member.

  Moreover, in Examples 1-3, although the latching | locking part was comprised by the bending part of the edge part of a heat conductive member, even if it attaches another member to a heat conductive member instead of a bending part and comprises a latching part, it is the same. An effect is obtained.

  Moreover, the subject of Examples 1-3 demonstrated above originates in the difference in the linear expansion coefficient of a supporting member and a heat conductive member, and it generate | occur | produces unless these are the same materials. Therefore, when the heat conducting member and the support member are formed of different materials, the effect of the present invention is achieved.

  The configurations of the first to third embodiments can be applied not only to the fixing device but also to an image heating device that heats a toner image.

18 Fixing Device 32 Pressure Roller 36 Film 37 Heater 37a Substrate 37b Heating Resistor 38 Support Member 38b Hole 39 Heat Conducting Member 39a Bending Part 380 Support Member 381 Support Member 382 Support Member 390 Heat Conducting Member 390b Bending Part 391 Heat Conducting Member 391a Bending portion 391c Bending portion 391d Bending portion 392 Heat conducting member 392a Bending portion 392c Bending portion 392d Bending portion G Drive gear P Recording material N Nip portion t Unfixed toner image

Claims (8)

A heating rotor ,
A long heater having a substrate and a heating resistor formed on the substrate and contacting the heating rotator;
A heat conduction member having a long and narrow shape in the longitudinal direction of the heater and having a heat conductivity higher than that of the substrate, the heat conduction being in contact with the surface of the heater opposite to the surface in contact with the heating rotating body. Members,
A support member that supports the heater via the heat conducting member;
An image heating apparatus for heating a toner image on a recording material with heat of the heater via the heating rotator ,
The heat conducting member has a locking portion at an end portion in a short direction of the heat conducting member ,
The support member has a locked portion to which the locking portion is locked,
And characterized in that the locking portion is said by being engaged with the engaged portion, the longitudinal position of the thermally conductive member against said support member of said heat conducting member is configured to determined Image heating device. A second locking portion provided in a position closer to one end portion of the heat conducting member in the longitudinal direction than the first locking portion in the longitudinal direction;
A third locking portion provided at a position closer to the other end portion of the heat conducting member in the longitudinal direction than the first locking portion in the longitudinal direction;
Have
The support member includes a first locked portion and a second locked portion in which the first locking portion, the second locking portion, and the third locking portion are locked, respectively. And a third locked portion,
The longitudinal position of the heat conducting member with respect to the support member is determined by the first locking portion being locked to the first locked portion,
The second engaging portion and the third engaging portion are respectively engaged with the second locked portion and the third locked portion, whereby the heat conducting member with respect to the support member is The image heating apparatus according to claim 1, wherein positions of the one end portion and the other end portion in the lateral direction are restricted. The heating rotator is a cylindrical film,
A roller that forms a nip portion that conveys the recording material together with the heater through the film;
The locking portion includes an image heating apparatus according to claim 1, characterized in Tei Rukoto provided in the end portion in the lateral direction of the heat conducting member upstream side in the transport direction of the recording material. The heating rotator is a cylindrical film,
A roller that forms a nip portion that conveys the recording material together with the heater through the film;
3. The image heating apparatus according to claim 2, wherein the first locking portion is provided at an end portion in the short-side direction of the heat conducting member on an upstream side in a recording material conveyance direction. . The locking portion includes an image heating apparatus according to claim 1 or 3, characterized in that provided in the longitudinal direction substantially in the center of the heat conducting member. The first locking portion is provided at substantially the center in the longitudinal direction of the heat conducting member, and each of the second locking portion and the third locking portion is the one of the heat conducting members. The image heating apparatus according to claim 2, wherein the image heating apparatus is provided at an end portion and the other end portion. An apparatus according to any one of claims 1 to 6, wherein the heat conducting member is characterized in that an aluminum plate. Wherein the support member, An apparatus according to any one of claims 1 to 7, characterized in that it has a regulating portion for regulating the movement in the transverse direction of the heater.