JP6439427B2 - Fixing apparatus and image forming apparatus - Google Patents

Description

  The present invention relates to an image forming apparatus such as an electrophotographic copying machine, a printer, and a facsimile, and more particularly to a heating type fixing device mounted on such an image forming apparatus.

  The image forming apparatus forms a toner image on an image carrier based on image information, transfers the toner image onto a recording material such as paper or an OHP sheet, and passes the recording material carrying the toner image through a fixing device. The toner image is fixed on the recording material by heat and pressure.

  As a fixing device that realizes energy saving, a technique of heating a film by a resistance heater in which a resistance heating element is formed on a ceramic or glass substrate has been proposed (for example, see Patent Document 1).

  The fixing device described in Patent Document 1 is sandwiched between a plate-like heating body and a pressure roller that are in contact with a thin-walled cylindrical heat-resistant film so that the film and the recording material are brought into close contact with each other, and gives thermal energy to the recording material. It is a configuration. This fixing device can realize energy saving by heating a thin film by a resistance heater in which a resistance heating element is formed on a ceramic substrate such as alumina.

  However, in the fixing device described in Patent Document 1, when a thin film is heated by a resistance heater in which a resistance heating element is formed on a ceramic substrate such as alumina, most of ceramic materials maintain electrical insulation, It is difficult to increase the thermal conductivity. Therefore, there is a problem that the heat conduction ability in the heater is poor and energy saving cannot be achieved. In addition, since the heat conduction in the longitudinal direction perpendicular to the recording material conveyance direction is poor and it is difficult to make the temperature uniform, the temperature of the region where the recording material does not pass rises when the recording material is continuously fed. There is also a problem of end temperature rise.

  In order to solve such a problem, a fixing device is known in which an insulating layer and a resistance heating element are integrally formed in order on a metal substrate, and the thin cylindrical heat-resistant film is heated via the metal substrate. (For example, refer to Patent Document 2).

  However, in the fixing device described in Patent Document 2, since the metal substrate slides with the heat resistant film, it is necessary to reduce friction between the metal substrate and the heat resistant film and reduce wear of the heat resistant film. Need to be coated. Since this coating deteriorates with time, the fixing device described in Patent Document 2 has a configuration as a heating body in which the resistance heating element and the metal substrate are integrated, and therefore is replaced for each heating body. Since the resistance heating element is an expensive member, it is not preferable to replace the heating element for each heating element from the viewpoint of the running cost of the apparatus.

  An object of the present invention is to provide a fixing device that is excellent in the heat conduction function of a heater, can suppress an increase in end temperature, and can reduce running costs.

In order to solve the above-described problem, a fixing device according to a first aspect of the present invention includes:
A belt-like fixing member that rotates in contact with an unfixed image;
A pressing member that forms a fixing nip portion with the belt-shaped fixing member;
In a fixing device comprising: a heater member that heats the belt-shaped fixing member; and a holding unit that holds the heater member.
The heater member includes a long base extending in a direction orthogonal to the recording medium conveyance direction, and a heating element formed on the fixing nip side from the base,
A sliding member that covers the surface of the heater member with which the belt-shaped fixing member contacts;
A heat transfer member that transfers heat from the heater member to the belt-shaped fixing member between the sliding member and the heater member;
The heat transfer member is composed of a plurality of members,
Of the plurality of members of the heat transfer member, the member disposed at a position closest to the heater member is an elastic member,
The sliding member is formed by surface-treating at least the surface on the fixing nip portion side of the heat transfer member,
The heat transfer member is detachable.

  According to the present invention, it is possible to provide a fixing device that is excellent in the heat conduction function of the heater, can suppress an increase in end temperature, and can reduce running costs.

1 is a configuration diagram schematically showing an image forming apparatus according to a first embodiment of the present invention. FIG. 2 is a configuration diagram schematically illustrating a fixing device of the image forming apparatus illustrated in FIG. 1. FIG. 2 is a configuration diagram schematically illustrating a nip forming member of the image forming apparatus illustrated in FIG. 1. FIG. 8 is a perspective view showing a modification of the fixing device of the image forming apparatus shown in FIG. 1. FIG. 6 is a configuration diagram schematically illustrating a fixing device of an image forming apparatus according to a second embodiment of the present invention. FIG. 10 is a configuration diagram schematically illustrating a fixing device of an image forming apparatus according to a third embodiment of the present invention. FIG. 10 is a configuration diagram schematically illustrating a fixing device of an image forming apparatus according to a fourth embodiment of the present invention.

  FIG. 1 shows a monochrome printer as an example of an image forming apparatus according to the first embodiment of the present invention, which will be described based on this. Naturally, the present invention applies to a known color image forming apparatus. Is applicable. As is known, a monochrome printer is provided with predetermined devices necessary for forming an image around a photosensitive member 8 as an image carrier, such as a charging unit, an exposure unit, and a developing unit. That is, a charging roller 18 as a charging means, a mirror 20 constituting an exposure means, a developing device 22 having a developing roller 22a as a developing means, a transfer device 10, a cleaning device 24 having a cleaning blade 24a, and the like are arranged. Yes. Then, between the charging roller 18 and the developing device 22, exposure light Lb is irradiated to the exposure unit 26 on the photoconductor 8 via the mirror 20 and scanned. A sheet feeding unit 4 is disposed below the printer, and a registration roller pair (positioning roller pair) 6 is provided in the middle of the sheet conveyance path to the image forming unit. At the end of the sheet conveyance path, a fixing device 12 including a fixing belt 28, a heater member 56, and a pressure roller 30 as main components is provided.

  The paper feed means 4 feeds paper feed trays 14 in which sheets Pa as recording media are stored in a stacked state, and paper Pa stored in the paper feed tray 14 one by one in order from the top. It has a paper roller 16 and the like. The paper Pa sent out by the paper supply roller 16 is temporarily stopped by the registration roller pair 6. Then, after correcting the posture deviation, at the timing synchronized with the rotation of the photoconductor 8, that is, the front end of the toner image formed on the photoconductor 8 coincides with the predetermined position of the front end of the paper Pa in the transport direction. At timing, it is sent to the transfer portion N by the registration roller pair 6.

  The image forming operation in this printer is performed in the same manner as before. That is, when the photosensitive member 8 starts to rotate, the surface of the photosensitive member 8 is uniformly charged by the charging roller 18, and the exposure light Lb is irradiated and scanned on the exposure unit 26 based on the image information to correspond to an image to be created. An electrostatic latent image is formed. The electrostatic latent image is moved to a position facing the developing device 22 by the rotation of the photosensitive member 8, where toner is supplied to be visualized to form a toner image. The toner image formed on the photoconductor 8 is transferred onto the paper Pa that has entered the transfer portion N at a predetermined timing by applying a transfer bias of the transfer device 10. The paper Pa carrying the toner image as an unfixed image is conveyed toward the fixing device 12, fixed by the fixing device 12, and then discharged and stacked on a discharge tray outside the apparatus. Residual toner remaining on the photosensitive member 8 without being transferred at the transfer portion N reaches the cleaning device 24 as the photosensitive member 8 rotates. Then, while passing through the cleaning device 24, it is scraped off and cleaned by the cleaning blade 24a. Thereafter, the residual potential on the photoconductor 8 is removed by a known charge eliminating means and prepared for the next image forming step.

Next, the configuration of the fixing device according to the present embodiment will be described with reference to FIG.
The fixing device 12 includes an endless fixing belt (belt-shaped fixing member; hereinafter, simply referred to as a fixing belt) 28 that is a flexible heat-resistant film, and a pressure roller 30 as a pressing member that comes into contact with the outer peripheral surface thereof. And a heater member 56. The heater member 56 is composed of heat transfer members 50 and 51 for equalizing the heat in the axial direction (longitudinal direction) of the fixing belt 28 and a sliding member that reduces friction between the fixing belt 28 and the pressure roller 30. A nip forming member for forming the fixing nip portion SN is formed.

  A thermistor 34 that detects the surface temperature of the fixing belt 28 is provided downstream of the fixing nip SN. Based on the detection information of the thermistor 34, the heating control means 42 controls the power supply 40 that supplies power to the heater member 56. The heating control means 42 means a microcomputer including a CPU, ROM, RAM, I / O interface and the like.

  The fixing belt 28 has a nickel base having an outer diameter of 30 mm and a thickness of 10 to 70 μm, an elastic layer coated on the surface of the base, and a release layer formed on the surface. The elastic layer is made of silicone rubber and has a thickness of 50 to 150 μm. The release layer that enhances the durability and secures the release property is formed of a fluorine-based resin such as PFA or PTFE, and is provided with a thickness of 5 to 50 μm. The material of the substrate is not limited to nickel, and may be formed of a heat resistant resin material such as SUS or polyimide (PI).

  The pressure roller 30 has an outer diameter of 30 mm, and includes a hollow iron core 30a, an elastic layer 30b formed on the surface of the core 30a, and a release layer 30c formed on the surface thereof. ing. The elastic layer 30b is made of silicone rubber and has a thickness of 5 mm. The release layer 30c is formed of a fluororesin (PFA or PTFE) layer having a thickness of about 40 μm and ensures release properties. As is known, the pressure roller 30 is pressed against the nip forming member 55 via the fixing belt 28 by an urging unit. The pressure roller 30 is rotated by a driving force transmitted from a driving source such as a motor provided in the image forming apparatus via a gear. The fixing belt 28 is rotated by the pressure roller 30.

  Next, the nip forming member will be described with reference to FIG.

  The nip forming member 55 includes a heater member 56, heat transfer members 50 and 51 for heat equalization in the axial direction (longitudinal direction) of the fixing belt 28, and a sliding member that reduces friction with the fixing belt 28. A fixing nip SN is formed with the pressure roller 30. The heater member 56 heats the fixing belt 28 via the first heat transfer member 50 to increase the temperature of the fixing belt 28 and heat and fix the unfixed image conveyed to the fixing nip portion SN. .

  The heater member 56 is a plate composed of a long base material 56b extending in the axial direction of the fixing belt 28, and a resistance heating element 56a as a heating element disposed on the fixing nip SN side from the base material 56b. It is a heating element in the shape. For example, a structure in which a resistance heating element 56a made of ruthenium oxide or the like is printed on a low thermal conductivity base material 56b made of glass or the like and fired, and an overcoat (OC) layer is further formed thereon. It is. The OC layer located on the fixing nip SN side from the base material 56b is formed of glass or the like, and is thinner than the base material 56b, and is more likely to transfer heat to the OC layer side than heat transfer to the base material 56b side. It plays a role as an insulating layer.

  The heater member 56 is in contact with the fixing belt 28 via the first heat transfer member 50. The first heat transfer member 50 is made of a highly heat conductive material such as copper or aluminum, and efficiently transfers the heat of the heater member 56 to the fixing belt 28. Further, it contributes to the improvement of heat conductivity in the heater longitudinal direction, and the temperature deviation in the longitudinal direction of the fixing belt 28 can be reduced.

  By the way, since both the heater member 56 and the first heat transfer member 50 are composed of highly rigid members, it is difficult to uniformly contact the entire longitudinal direction due to the influence of surface roughness, warpage, and waviness. . In order to avoid such a problem, a second heat transfer member 51 having an elastic characteristic is interposed between the heater member 50 and the first heat transfer member 50. For the second heat transfer member 51, silicone grease to which metal particles such as zinc oxide are added, a heat conductive sheet (TIM: Thermal Interface Material), or the like can be used. In addition, the heat transfer member is not limited to an aspect constituted by two parts, and may be constituted by a plurality of parts of three or more parts. In this case, among the plurality of heat transfer members, a member disposed at a position closest to the heater member 56 is an elastic member having elastic characteristics.

  The base 56b made of glass or the like has a thermal conductivity of about 1.3 to 1.6 W / m · K. On the other hand, the heat conductivity of the first heat transfer member 50 made of copper is about 52400 W / m · K, and the heat conductivity of the first heat transfer member 50 made of aluminum is 240 W / m · K. Since it is about K, it is much higher than the thermal conductivity of the substrate 56b. Since the thermal conductivity of the second heat transfer member 51 composed of silicone grease added with metal particles such as zinc oxide is about 4 to 10 W / m · K, it is compared with the thermal conductivity of the base material 56b. Is expensive. Therefore, the heat from the resistance heating element 56a can be efficiently transferred to the first heat transfer member 50 and the second heat transfer member 51 having a higher thermal conductivity than the base material 56b, and thus to the fixing belt 28. .

  The second heat transfer member 51 may be a material such as a graphite sheet having anisotropic thermal conductivity. Since the thermal conductivity of the graphite sheet is higher in the plane direction than in the thickness direction, the temperature can be effectively equalized when the temperature becomes non-uniform in the longitudinal direction of the fixing nip portion SN. Further, by reducing the thickness of the second heat transfer member 51, the heat from the heater member 56 can be efficiently conducted to the fixing nip SN, so that the temperature raising performance of the nip surface can be improved.

  The first heat transfer member 50 slides in contact with the fixing belt 28 and wears the fixing belt 28. Therefore, the surface of the first heat transfer member 50 that is in sliding contact with the fixing belt 28 is subjected to a surface treatment such as a low friction coating as a sliding member. That is, the surface of the heater member 56 with which the fixing belt 28 contacts is covered by surface treatment. As a result, wear of the fixing belt 28 is reduced. As a material for the surface treatment, DLC (diamond-like carbon), PTFE (polytetrafluoroethylene) or the like having a low friction coefficient is suitable. Considering the heat transfer performance from the first heat transfer member 50 to the fixing belt 28, the surface treatment layer is preferably a thin layer of about 2 to 50 μm. The portion to be surface-treated is not limited to the portion that is in sliding contact with the fixing belt 28.

  A heater holder 57 as a holding means for holding the heater member 56 is supported by a stay (support member) 61 connected to the apparatus side plate, prevents the member from being bent by the pressure received from the pressure roller 30, and is uniform in the longitudinal direction. The nip width can be obtained. The heater holder 57 has a box shape with one surface facing the fixing belt 28 opened, and accommodates the heater member 56 therein.

  By the way, the heater holder 57 easily receives a heat from the heater member 56 and becomes high temperature, and may be damaged. Therefore, the heater holder 57 is formed of a resin having high heat resistance such as LCP (liquid crystal polymer), PPS (poniphenylene sulfide), PAI (polyamideimide), PI (polyimide), PEEK (polyetheretherketone). As a result, the heater holder 57 can be prevented from being damaged. The heater holder 57 can be made of a resin having a lower thermal conductivity to improve heat insulation performance. Furthermore, the heater holder 57 is a position that is not adjacent to the resistance heating element 56a, and is in contact with two places, thereby reducing the amount of heat flowing from the first heat transfer member 50 to the heater holder 57 and transferring heat to the first heat transfer side. The heat can be efficiently transmitted to the first heat transfer member 50 and the second heat transfer member 51, and thus to the fixing belt 28. In addition, the location where the heater holder 57 contacts the heater member 56 is not limited to two modes.

  The first heat transfer member 50 includes a nip forming portion 50a that forms a fixing nip portion SN via the fixing belt 28, and a pressure roller 30 from both ends of the nip forming portion 50a in the rotation direction of the fixing belt 28. And an extending portion 50b extending in a direction opposite to the direction.

  At the distal end of the extending portion 50 b, there is a hook portion 50 c as a locking portion that is hooked on the heat holder 57 and has a shape protruding in a direction in which both the extending portions 50 b face each other. A plurality of hooks 50 c are provided across the longitudinal direction of the first heat transfer member 50. When the first heat transfer member 50 is assembled to the heat holder 57, the hook portion 50 c of the first heat transfer member 50 is hooked on the heater holder 57. Therefore, the first heat transfer member 50 is connected to the heater holder 57. There will be no departure.

  On the other hand, when the first heat transfer member 50 is removed from the heater holder 57, the first heat transfer member 50 can be removed from the heater holder 57 by removing the hook 50 c from the heater holder 57.

  Thus, since the first heat transfer member 50 can be configured to be detachable from the heater member 56, the surface treatment such as coating applied to the first heat transfer member 50 needs to be replaced due to deterioration over time. In this case, the first heat transfer member 50 can be individually replaced without replacing the heater member 56. Therefore, the running cost of the apparatus can be reduced.

  By the way, when the width of the resistance heating element 56a in the sheet conveyance direction and the nip width are substantially the same, when the positional deviation of the resistance heating element 56a and / or the pressure roller 30 in the sheet conveyance direction occurs, the resistance heating element 56a. A gap is generated between 56 a and the fixing belt 28. When this gap is generated, the heat transfer to the fixing belt 28 is not sufficiently performed, so that the heater member 56 itself is heated. If the temperature of the heater member 56 itself is increased, the heat resistance temperature of the heater holder 57 may be exceeded and the heater holder 57 may melt. For this reason, it is necessary to align the resistance heating element 56a and the pressure roller 30 with high accuracy, which causes a problem of cost increase. Further, if the nip width is unnecessarily widened, problems such as toner hot offset and increase in curling of the recording material occur due to excessive supply of heat to the recording material.

  In order to solve such a problem, the width of the heat transfer members 50 and 51 according to the present embodiment in the sheet conveyance direction is sufficiently wider than the width of the resistance heating element 56a in the sheet conveyance direction.

  By making the width of the heat transfer members 50 and 51 in the sheet conveyance direction wider than the width of the resistance heating element 56a in the sheet conveyance direction, the heat generated in the resistance heating element 56a It is diffused by the second heat transfer member 51. Therefore, the heater holder 57 does not melt. Further, it is not necessary to align the positions of the resistance heating element 56a and the pressure roller 30 with high accuracy. Since the nip width is not unnecessarily widened, problems such as toner hot offset and increase in curling of the recording material do not occur.

  Instead of providing the hook portion 50c at the tip of the extending portion 50b, as shown in FIG. 4, there is an insertion portion 50d having a notch in the same direction in the longitudinal direction of the first heat transfer member 50. You may do it. Then, the insertion part 50d is inserted into the hole 57a of the heater holder 57, and the first heat transfer member 50 is slid (moved) in the direction having the notch, whereby the first heat transfer member 50 is moved to the heater holder 57. Can be assembled.

  On the other hand, when the first heat transfer member 50 is removed from the heater holder 57, the first heat transfer member 50 is slid in the direction opposite to the direction having the notch and pulled out, so that the first heat transfer member 50 is removed. It can be removed from the heater holder 57.

  Subsequently, an image forming apparatus according to a second embodiment of the present invention will be described. Note that components common to those in the image forming apparatus according to the first embodiment are denoted by corresponding reference numerals and detailed description thereof is omitted, and different components are described in detail with reference to the drawings.

  The second embodiment is different from the first embodiment in that the shape of the first heat transfer member is different. This will be specifically described below.

  The first heat transfer member 150 includes a nip forming portion 150a that forms the fixing nip portion SN via the fixing belt 28, and a heater holder that contacts the fixing belt 28 from both ends in the rotation direction of the fixing belt 28 of the nip forming portion 150a. 157 has a connecting portion 150e that covers a part of 157, and an extending portion 150b that extends from both ends of the connecting portion 150e in a direction opposite to the direction in which the pressure roller 30 exists.

  At the tip of the extended portion 150b, there is a hooking portion 150c as a locking portion that is hooked on the heat holder 157 and has a shape protruding in a direction in which both the extended portions 150b face each other. A plurality of the hooks 150 c are provided along the longitudinal direction of the first heat transfer member 150. When the first heat transfer member 150 is assembled to the heat holder 157, the hook portion 150 c of the first heat transfer member 150 is hooked on the heater holder 157. Therefore, the first heat transfer member 150 is connected to the heater holder 157. There will be no departure.

  On the other hand, when the first heat transfer member 150 is removed from the heater holder 157, the first heat transfer member 150 can be removed from the heater holder 157 by removing the hook 150 c from the heater holder 157.

  Thus, since the first heat transfer member 150 can be configured to be detachable from the heater member 56, the surface treatment such as coating applied to the first heat transfer member 150 needs to be replaced due to deterioration over time. In this case, the first heat transfer member 150 can be individually replaced without replacing the heater member 56. Therefore, the running cost of the apparatus can be reduced. Further, when the coating process is performed on the nip forming portion 150a and the connecting portion 150e that are in contact with the fixing belt 28, wear of the fixing belt 28 can be reduced.

  Subsequently, an image forming apparatus according to a third embodiment of the present invention will be described. Note that components common to those in the image forming apparatus according to the first embodiment are denoted by corresponding reference numerals and detailed description thereof is omitted, and different components are described in detail with reference to the drawings.

  The third embodiment is different from the first embodiment in that a sliding sheet 250 as a sliding member is provided instead of providing the first heat transfer member. This will be specifically described below.

  The sliding sheet 250 is formed of a thin sheet having a low friction property. The sliding sheet 250 with the adhesive applied on the back surface covers the surface of the heater member 56 having the resistance heating element 56a, and its end is opposite to the surface of the heater member 56 having the resistance heating element 56a. The sliding sheet 250 can be attached to the heater member 56 by extending to the surface. In addition, the sliding sheet 250 hooks the sliding sheet 250 by hooking a hole formed in the sliding sheet 250 on a protrusion on the surface opposite to the surface having the resistance heating element 56a of the heater member 56. You may attach to the heater member 56. FIG.

  On the other hand, the sliding sheet 250 can be removed from the heater member 56 by peeling the sliding sheet 250 from the heater member 56.

  Thus, since the sliding sheet 250 can be configured to be detachable from the heater member 56, the sliding sheet 250 can be slid without replacing the heater member 56 when the sliding sheet 250 needs to be replaced due to deterioration over time. Sheets 250 can be replaced individually. Therefore, the running cost of the apparatus can be reduced.

  Subsequently, an image forming apparatus according to a fourth embodiment of the present invention will be described. Note that components common to those in the image forming apparatus according to the first embodiment are denoted by corresponding reference numerals and detailed description thereof is omitted, and different components are described in detail with reference to the drawings.

  The fourth embodiment is different from the first embodiment in that a sliding sheet 350 as a sliding member is provided instead of providing the first heat transfer member. This will be specifically described below.

  The sliding sheet 350 is formed from a thin sheet having low friction. The sliding sheet 350 with the adhesive applied on the back surface covers the surface of the heater member 56 having the resistance heating element 56a and a part of the heater holder 357 in contact with the fixing belt 28, and the end thereof is the heater of the heater holder 375. It can extend to the surface opposite to the surface having the member 56. Thereby, the sliding sheet 350 can be attached to the heater holder 375. In addition, the sliding sheet 350 hooks the sliding sheet 250 to the heater member by hooking a hole formed in the sliding sheet 350 on a protrusion on the surface opposite to the surface having the heater member 56 of the heater holder 375. You may attach to 56.

  On the other hand, the sliding sheet 350 can be removed from the heater member 56 by peeling the sliding sheet 350 from the heater holder 375.

  Thus, since the sliding sheet 350 can be configured to be detachable from the heater member 56, the sliding sheet 250 can be slid without replacing the heater member 56 when the sliding sheet 250 needs to be replaced due to deterioration over time. Sheets 350 can be replaced individually. Therefore, the running cost of the apparatus can be reduced. Further, when a sliding sheet is installed at a portion where the fixing belt 28 contacts, wear of the fixing belt 28 can be reduced.

  As mentioned above, although embodiment of this invention was described, this invention is not limited to this. For example, instead of subjecting the first heat transfer members 50 and 150 to surface treatment, a sliding sheet may be attached. It should be noted that the materials and dimensions of each component introduced in the above-described embodiment are merely examples, and it is needless to say that various materials and dimensions can be selected within a range where the effects of the present invention can be exhibited.

28 fixing belt (an example of a belt-like fixing member)
30 Pressure roller (an example of a pressing member)
50 1st heat-transfer member (an example of heat-transfer member)
50c Hook (an example of a locking part)
51 2nd heat transfer member (an example of heat transfer member)
56 Heater member 56a Resistance heating element (an example of a heating element)
56b Base material 57 Heater holder (an example of holding means)
SN fixing nip

JP-A-6-95540 JP-A-8-272240

Claims (8)

A belt-like fixing member that rotates in contact with an unfixed image;
A pressing member that forms a fixing nip portion with the belt-shaped fixing member;
In a fixing device comprising: a heater member that heats the belt-shaped fixing member; and a holding unit that holds the heater member.
The heater member includes a long base extending in a direction orthogonal to the recording medium conveyance direction, and a heating element formed on the fixing nip side from the base,
A sliding member that covers the surface of the heater member with which the belt-shaped fixing member contacts;
A heat transfer member that transfers heat from the heater member to the belt-shaped fixing member between the sliding member and the heater member;
The heat transfer member is composed of a plurality of members,
Of the plurality of members of the heat transfer member, the member disposed at a position closest to the heater member is an elastic member,
The sliding member is formed by surface-treating at least the surface on the fixing nip portion side of the heat transfer member,
The fixing device, wherein the heat transfer member is detachable.   The fixing device according to claim 1, wherein the heat transfer member includes an engaging portion that engages with the holding unit. The fixing device according to claim 1 , wherein at least one member among the plurality of members of the heat transfer member has anisotropy in thermal conductivity. Among the plurality of members of the heat transfer member, at least one member, wherein the planar direction of the thermal conductivity has a higher anisotropy than the thermal conductivity in the thickness direction, one of claims 1 to 3 the fixing device according to an item or. The fixing device according to claim 1 , wherein a heat conductivity of the heat transfer member is higher than a heat conductivity of the base material . The fixing device according to claim 1 , wherein a width of the heat transfer member in a recording medium conveyance direction is wider than a width of the heating element in the recording medium conveyance direction. The holding means accommodates the heater member in a box-shaped interior with one side open,
The fixing device according to claim 1 , wherein the sliding member covers a surface of the holding unit in contact with the belt-shaped fixing member. An image forming apparatus comprising the fixing device according to claim 1 .

Images