Image forming device

Abstract

An image forming device capable of shortening the time until printing starts is provided. The image forming device of an embodiment includes an image forming unit and a fixing device. The image forming unit forms an image on a sheet. The fixing device includes a cylindrical body, a heater, a first heat-conducting component, and a second heat-conducting component. The heater is located in the cylindrical body, opposite to a heated area that is a part of the circumference of the cylindrical body. The heater heats the heated area. The first heat-conducting component is arranged on the opposite side of the heated area relative to the heater. The heat conductivity of the first heat-conducting component in a direction orthogonal to the first direction is greater than the heat conductivity of the first heat-conducting component in a first direction in which the heated area is opposite to the heater. The second heat-conducting component is arranged on the opposite side of the first heat-conducting component from the heater, and has a recessed portion on the outer surface facing the first heat-conducting component.

Description

Technical Field

[0001] Embodiments of the present invention relate to an image forming apparatus. Background Art

[0002] Conventional technology utilizes an image forming device that forms an image on a sheet. The image forming device fixes toner to the sheet. Toner is a type of recording agent. Image forming devices are required to shorten the time it takes to start printing. Summary of the Invention

[0003] Problems to be solved by the invention

[0004] An object of the present invention is to provide an image forming apparatus capable of shortening the time until printing starts.

[0005] Solutions to Problems

[0006] An image forming apparatus according to an embodiment includes an image forming unit and a fixing device. The image forming unit forms an image on a sheet. The fixing device includes a cylindrical body, a heater, a first heat-conducting component, and a second heat-conducting component. The heater is located in the cylindrical body, opposite to a heated area that is a portion of a circumference of the cylindrical body. The heater heats the heated area. The first heat-conducting component is arranged on the opposite side of the heated area relative to the heater. The heat conductivity of the first heat-conducting component in a direction orthogonal to the first direction is greater than the heat conductivity of the first heat-conducting component in a first direction in which the heated area is opposite to the heater. The second heat-conducting component is arranged on the opposite side of the first heat-conducting component from the heater, and has a recessed portion on the outer surface facing the first heat-conducting component. BRIEF DESCRIPTION OF THE DRAWINGS

[0007] Figure 1 It is a schematic structural diagram of the image forming apparatus according to the embodiment.

[0008] Figure 2 This is a diagram showing the hardware configuration of the image forming apparatus according to the embodiment.

[0009] Figure 3 It is a front cross-sectional view of a fixing device in the image forming apparatus according to the embodiment.

[0010] Figure 4 yes Figure 3 An enlarged view of the main parts.

[0011] Figure 5 yes Figure 4 AA arrow direction view.

[0012] Figure 6It is a front cross-sectional view of a heater unit in an image forming apparatus according to a first modified example of the embodiment.

[0013] Figure 7 It is a front cross-sectional view of a heater unit in an image forming apparatus according to a second modified example of the embodiment.

[0014] Figure 8 It is a front cross-sectional view of a heater unit in an image forming apparatus according to a third modified example of the embodiment.

[0015] Figure 9 It is a front cross-sectional view of a heater unit in an image forming apparatus according to a fourth modified example of the embodiment.

[0016] Explanation of symbols

[0017] 1, 201, 202, 203, 204: image forming device; 3: image forming unit; 30: fixing device; 36: cylindrical body; 43: heater; 45: first heat-conducting member; 46: second heat-conducting member; 102: third heat-conducting member; 361: heated area; 461: recess; Y: axial direction; Z: first direction. DETAILED DESCRIPTION

[0018] Hereinafter, an image forming apparatus according to an embodiment will be described with reference to the drawings.

[0019] Figure 1 FIG2 is a schematic diagram of the structure of the image forming apparatus 1 according to the embodiment. The image forming apparatus 1 performs a process of forming an image on a sheet S.

[0020] The image forming apparatus 1 includes a housing 10 , a scanner section 2 , an image forming unit 3 , a sheet feeding section 4 , a conveying section 5 , a paper discharge tray 7 , a reversing unit 9 , a control panel 8 , and a control section 6 .

[0021] The housing 10 forms the outer appearance of the image forming apparatus 1 .

[0022] The scanner unit 2 reads image information of the copy object as light and dark, and generates an image signal, and outputs the generated image signal to the image forming unit 3 .

[0023] The image forming unit 3 forms an output image using a recording medium such as toner based on an image signal received from the scanner unit 2 or an external source. The output image is hereinafter referred to as a toner image. The image forming unit 3 transfers the toner image onto the surface of the sheet S. The image forming unit 3 heats and pressurizes the toner image on the surface of the sheet S, fixing the toner image to the sheet S. The image forming unit 3 forms an image on the sheet S.

[0024] The sheet feeding section 4 feeds the sheets S one by one to the conveying section 5 in accordance with the timing of forming a toner image by the image forming unit 3. The sheet feeding section 4 includes a sheet storage section 20 and a pickup roller 21.

[0025] The sheet storage section 20 stores sheets S of predetermined sizes and types.

[0026] The pickup roller 21 takes out the sheets S one by one from the sheet storage portion 20 . The pickup roller 21 supplies the taken-out sheets S to the conveying portion 5 .

[0027] The conveying section 5 conveys the sheet S supplied from the sheet supply section 4 to the image forming unit 3 . The conveying section 5 includes a conveying roller 23 and a registration roller 24 .

[0028] The conveying roller 23 conveys the sheet S supplied from the pickup roller 21 toward the registration roller 24 . The conveying roller 23 causes the leading end of the sheet S in the conveying direction to abut against the nip N of the registration roller 24 .

[0029] The registration roller 24 aligns the position of the leading end of the sheet S in the conveying direction by bending the sheet S at the nip N. The registration roller 24 conveys the sheet S according to the timing at which the image forming unit 3 transfers the toner image to the sheet S.

[0030] The image forming unit 3 will be described.

[0031] The image forming unit 3 includes a plurality of image forming sections 25 , a laser scanning unit 26 , an intermediate transfer belt 27 , a transfer section 28 , and a fixing device 30 .

[0032] The image forming unit 25 includes a photosensitive drum 29. The image forming unit 25 forms a toner image corresponding to an image signal from the scanner unit 2 or externally on the photosensitive drum 29. The plurality of image forming units 25 form toner images using yellow, magenta, cyan, and black toners, respectively.

[0033] A charger, a developer, and other components are arranged around the photosensitive drum 29. The charger charges the surface of the photosensitive drum 29. The developer contains developer containing yellow, magenta, cyan, and black toners. The developer develops the electrostatic latent image on the photosensitive drum 29. A toner image formed by the toners of each color is formed on the photosensitive drum 29.

[0034] The laser scanning unit 26 scans the charged photosensitive drum 29 with laser light L to expose the photosensitive drum 29. The laser scanning unit 26 exposes the photosensitive drum 29 of the image forming unit 25 of each color with different laser light LY, LM, LC, and LK. The laser scanning unit 26 forms an electrostatic latent image on the photosensitive drum 29.

[0035] The toner image on the surface of the photoconductive drum 29 is primarily transferred to the intermediate transfer belt 27 .

[0036] The transfer section 28 transfers the toner image primarily transferred onto the intermediate transfer belt 27 onto the surface of the sheet S at a secondary transfer position.

[0037] The fixing device 30 heats and pressurizes the toner image transferred to the sheet S so that the toner image is fixed to the sheet S.

[0038] The reversing unit 9 reverses the sheet S to form an image on the back side of the sheet S. The reversing unit 9 reverses the sheet S discharged from the fixing device 30 by turning the sheet S over. The reversing unit 9 conveys the reversed sheet S to the registration rollers 24 .

[0039] The paper discharge tray 7 places the sheet S on which an image is formed and discharged.

[0040] The control panel 8 is a part of an input unit for inputting information for an operator to operate the image forming apparatus 1. The control panel 8 includes a touch panel and various hardware keys.

[0041] The control unit 6 controls each unit of the image forming apparatus 1 .

[0042] Figure 2 This is a hardware configuration diagram of an image forming apparatus 1 according to an embodiment. Image forming apparatus 1 includes a CPU (Central Processing Unit) 91, memory 92, and auxiliary storage device 93, all connected via a bus, and executes programs. Through program execution, image forming apparatus 1 functions as a device including a scanner unit 2, an image forming unit 3, a sheet feeding unit 4, a conveying unit 5, a reversing unit 9, a control panel 8, and a communication unit 90.

[0043] The CPU 91 functions as the control unit 6 by executing programs stored in the memory 92 and the auxiliary storage device 93. The control unit 6 controls the operation of each functional unit of the image forming apparatus 1.

[0044] The auxiliary storage device 93 is formed using a storage device such as a hard disk device or a semiconductor storage device. The auxiliary storage device 93 stores information.

[0045] The communication unit 90 is configured to include a communication interface for connecting the device to an external device. The communication unit 90 communicates with the external device via the communication interface.

[0046] The fixing device 30 will be described in detail. Figure 3 As shown, the fixing device 30 includes a pressure roller 31 and a film unit 35 .

[0047] The pressure roller 31 forms a nip N with the film unit 35 . The pressure roller 31 presses the toner image on the sheet S that has entered the nip N. The pressure roller 31 rotates to convey the sheet S. The pressure roller 31 includes a core 32 , an elastic layer 33 , and a release layer.

[0048] The core metal 32 is formed into a cylindrical shape from a metal material such as stainless steel. Both axial ends of the core metal 32 are supported for rotation. The core metal 32 is driven by a motor. The core metal 32 abuts against a cam member. The cam member rotates to move the core metal 32 toward and away from the membrane unit 35.

[0049] The elastic layer 33 is formed of an elastic material such as silicone rubber and is formed on the outer peripheral surface of the core metal 32 with a constant thickness.

[0050] The mold release layer is formed of a resin material such as PFA (tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer) and is formed on the outer peripheral surface of the elastic layer 33 .

[0051] The hardness of the outer peripheral surface of the pressure roller 31 is preferably 40° to 70° at an ASKER-C hardness tester load of 9.8 N. This ensures the area of the nip portion N and the durability of the pressure roller 31 .

[0052] The pressure roller 31 can be moved toward and away from the film unit 35 by the rotation of the cam member. When the pressure roller 31 is moved toward the film unit 35 and pressed by the pressure spring, a nip N is formed. On the other hand, if a sheet S becomes jammed in the fixing device 30, the sheet S can be removed by moving the pressure roller 31 away from the film unit 35. When the cylindrical body 36 of the fixing device 30 is stopped, such as during sleep mode, plastic deformation of the cylindrical body 36 is prevented by moving the pressure roller 31 away from the film unit 35.

[0053] The pressure roller 31 is driven by a motor to rotate. When the pressure roller 31 rotates with the nip N formed, the cylindrical body 36 of the film unit 35 rotates accordingly. The pressure roller 31 rotates with the sheet S positioned in the nip N, thereby conveying the sheet S in the conveyance direction X.

[0054] The film unit 35 heats the toner image on the sheet S that has entered the nip N. The film unit 35 includes a cylindrical body 36 , a heater unit 37 , a supporting member 38 , a stay 39 , and a temperature sensing element 40 .

[0055] The cylindrical body 36 is formed into a cylindrical shape from a film or the like. It comprises, in order from the inner circumference, a base layer, an elastic layer, and a release layer. The base layer is formed into a cylindrical shape from a material such as nickel (Ni). The elastic layer is laminated on the outer circumference of the base layer. The elastic layer is formed from an elastic material such as silicone rubber. The release layer is laminated on the outer circumference of the elastic layer. The release layer is formed from a material such as PFA resin.

[0056] like Figure 4 and Figure 5 As shown, the heater unit 37 includes a heater 43 , a substrate 44 , a first heat conducting member 45 , and a second heat conducting member 46 .

[0057] The heater 43 is formed into a flat plate shape from a silver-palladium alloy or the like. The heater 43 is located within the cylindrical body 36. The heater 43 has a length in the axial direction Y of the cylindrical body 36. The axial direction Y is a direction perpendicular to the conveying direction X. Wiring is connected to the heater 43. When power is supplied to the heater 43 via the wiring, the heater 43 generates heat. The heater 43 faces a heated area 361, which is a portion of the circumference of the cylindrical body 36. The heater 43 heats the heated area 361. Hereinafter, the direction in which the heated area 361 and the heater 43 face each other is referred to as a first direction Z.

[0058] The first direction Z is the thickness direction of the heater 43. The conveying direction X and the axial direction Y are directions perpendicular to the first direction Z, respectively.

[0059] The substrate 44 is formed of a metal material such as stainless steel or a ceramic material such as aluminum nitride. The substrate 44 is in the shape of an elongated rectangular plate. The substrate 44 is located inside the cylindrical body 36. The substrate 44 has a length in the axial direction Y.

[0060] The substrate 44 is located on the opposite side of the heated region 361 of the heater 43. The heater 43 and wiring are fixed to a first surface 441 in the thickness direction of the substrate 44. The heater 43 is fixed to the center of the first surface 441 in the conveyance direction X.

[0061] The first heat-conducting member 45 is formed of graphite or the like in a flat plate shape with the first direction Z being the thickness direction. The first heat-conducting member 45 has anisotropic thermal conductivity. The first heat-conducting member 45 is located opposite the heated region 361 of the heater 43 across the substrate 44. The first heat-conducting member 45 is fixed to a second surface 442 of the substrate 44, which is opposite the first surface 441.

[0062] The first heat-conducting member 45 has a higher thermal conductivity in both the transport direction X and the axial direction Y than in the first direction Z. The thickness t1 of the first heat-conducting member 45 is not less than 10 μm (micrometers) and not more than 1000 μm. The thickness represents the length in the first direction Z. The thermal conductivity of the first heat-conducting member 45 in the first direction Z is not less than 1 W / (m·K) and not more than 20 W / (m·K). The thermal conductivity of the first heat-conducting member 45 in the transport direction X and the axial direction Y is not less than 300 W / (m·K) and not more than 2000 W / (m·K), respectively.

[0063] The second heat conducting member 46 is formed of copper, stainless steel, or the like in a flat plate shape with its thickness direction being the first direction Z. In the second heat conducting member 46, the heat conductivity is substantially constant regardless of the direction.

[0064] like Figure 4 As shown, the thickness t2 of the second heat-conducting member 46 is greater than the thickness t1 of the first heat-conducting member 45. The length T1 of the first heat-conducting member 45 in the conveying direction X and the length T2 of the second heat-conducting member 46 in the conveying direction X are the same. In the conveying direction X, the center of the first heat-conducting member 45 and the center of the second heat-conducting member 46 are aligned with each other.

[0065] The second heat-conducting member 46 is arranged on the side of the first heat-conducting member 45 opposite to the heater 43 (substrate 44 ).

[0066] like Figure 5 As shown, the length H1 of the first heat conducting member 45 in the axial direction Y and the length H2 of the second heat conducting member 46 in the axial direction Y are the same. The length H1 of the first heat conducting member 45 in the axial direction Y is longer than the length H3 of the heater 43 in the axial direction Y.

[0067] like Figure 4 and Figure 5 As shown, the second heat conducting member 46 has a recessed portion 461 on the outer surface facing the first heat conducting member 45 .

[0068] like Figure 4 As shown, the recess 461 is formed to include the range where the heater 43 is arranged in the conveying direction X. Figure 5 As shown, the recess 461 is formed so as to encompass the area where the heater 43 is disposed in the axial direction Y. The recess 461 preferably extends through the second heat conducting member 46 in the axial direction Y. The depth t3 of the recess 461 is not less than 0.1 mm and not more than 1.0 mm. The width T3 of the recess 461 (the length in the conveyance direction X) is not less than 1 mm and not more than 10 mm.

[0069] The recess 461 does not contact the first heat conducting member 45 . On the other hand, both sides of the second heat conducting member 46 in the conveying direction X of the recess 461 contact the first heat conducting member 45 . The first heat conducting member 45 and the second heat conducting member 46 are located in the cylindrical body 36 .

[0070] In the heater unit 37 , a heater 43 , a substrate 44 , a first heat-conducting member 45 , and a second heat-conducting member 46 are arranged in this order from the heated region 361 side.

[0071] The supporting member 38 is formed of a resin material such as a liquid crystal polymer. Figure 3 As shown, the support member 38 is arranged to cover the side of the heater unit 37 opposite to the heated region 361 and both sides in the conveying direction X. The support member 38 supports the heater unit 37 .

[0072] The support members 38 support the inner peripheral surface of the cylindrical body 36 at both end portions in the conveyance direction X of the heater unit 37 .

[0073] The stay 39 is formed of a steel plate material or the like. The cross section of the stay 39 perpendicular to the axial direction Y is U-shaped. The stay 39 is mounted on the side of the support member 38 opposite to the heated area 361 in such a manner that the opening of the U is blocked by the support member 38. The stay 39 has a length in the axial direction Y. Both ends of the stay 39 in the axial direction Y are fixed to the housing 10 of the image forming device 1. Thus, the membrane unit 35 is supported by the image forming device 1. The stay 39 increases the bending rigidity of the membrane unit 35. Flanges for limiting the movement of the cylindrical body 36 in the axial direction Y are mounted near both ends of the stay 39 in the axial direction Y.

[0074] The temperature sensing element 40 is arranged on the outer surface of the heater unit 37 on the side opposite to the heated region 361. The temperature sensing element 40 is arranged inside a hole 381 that penetrates the support member 38 in the first direction Z.

[0075] When printing begins in the image forming apparatus 1, the heater 43 heats the cylindrical body 36 to the fixing temperature. When the heater 43 generates heat from room temperature, for example, the temperature distribution of the heater 43 is highest at the center of the heater 43 in the conveyance direction X. The temperature distribution of the heater 43 decreases as it moves away from the center of the heater 43 in the conveyance direction X. Thus, the temperature distribution of the heater 43 forms a mountain-like shape with a peak temperature position. The recessed portion 461 of the second heat-conductive member 46 is formed to cover the center of the heater 43 in the conveyance direction X, which is the peak temperature position.

[0076] As described above, according to the image forming apparatus 1 of this embodiment, the heated region 361 of the cylindrical body 36 can be heated by the heater 43. The first heat-conducting member 45 has a higher thermal conductivity in the conveyance direction X and the axial direction Y, which are perpendicular to the first direction Z, than in the first direction Z. Heat generated by the heater 43 and transferred to the first heat-conducting member 45 can be transferred more in the conveyance direction X and the axial direction Y than in the first direction Z.

[0077] The second heat-conducting member 46 has a recessed portion 461. Because the recessed portion 461 is not in contact with the first heat-conducting member 45, most of the heat generated by the heater 43 is transferred to the cylindrical body 36 rather than the second heat-conducting member 46. This efficient heating of the cylindrical body 36 shortens the time until printing begins, preventing the image forming apparatus 1 from taking too long to recover.

[0078] The thickness t2 of the second heat conducting member 46 is thicker than the thickness t1 of the first heat conducting member 45. For example, the second heat conducting member 46 made of stainless steel can more reliably reinforce the first heat conducting member 45 made of graphite.

[0079] The recess 461 is formed so as to encompass the area where the heater 43 is disposed in the axial direction Y. In the axial direction Y, the heat generated by the heater 43 is transferred to the cylindrical body 36 rather than the second heat conducting member 46. Since the cylindrical body 36 is heated more efficiently, the time until printing can be further shortened.

[0080] The recess 461 penetrates the second heat-conducting member 46 in the axial direction Y. Heat generated by the heater 43 is not transferred to the second heat-conducting member 46 at any position in the axial direction Y, but is transferred to the cylindrical body 36. Since the cylindrical body 36 is heated more efficiently, the time until printing can be further shortened.

[0081] The image forming apparatus 1 of the present embodiment can have various structural modifications as described below.

[0082] like Figure 6 Like the heater unit 101 of the image forming apparatus 201 of the first modified example shown in FIG. , the heater unit 37 of this embodiment may also include a third heat-conducting member 102. The third heat-conducting member 102 is positioned between the first heat-conducting member 45 and the second heat-conducting member 46. The third heat-conducting member 102 is formed of copper, stainless steel, or the like into a flat plate shape with the first direction Z being the thickness direction. Preferably, the third heat-conducting member 102 does not have a recessed portion.

[0083] The length of the third heat-conducting member 102 in the axial direction Y is equal to the length H1 of the first heat-conducting member 45 in the axial direction Y and the length H2 of the second heat-conducting member 46 in the axial direction Y. The thickness of the third heat-conducting member 102 is not less than 50 μm and not more than 100 μm. More preferably, the thickness of the third heat-conducting member 102 is thinner than the thickness t2 of the second heat-conducting member 46.

[0084] The image forming apparatus 201 of the first modification includes the third heat conducting member 102. For example, when the heater 43 is pressed by the pressure roller 31 via the cylindrical body 36, deformation of the heater 43, substrate 44, first heat conducting member 45, and second heat conducting member 46 can be more reliably suppressed.

[0085] You can also Figure 7 As shown in the heater unit 104 of the image forming apparatus 202 of the second modified example, the heater unit 101 of the image forming apparatus 201 of the first modified example includes a second recess 462 in the second heat conducting member 46. In the image forming apparatus 202, the second heat conducting member 46 includes a pair of second recesses 462. The pair of second recesses 462 sandwich the recess 461 in the conveyance direction X. It should be noted that the number of second recesses 462 formed in the second heat conducting member 46 is not limited.

[0086] The entire range of the plurality of recesses 461 and 462 from the first end in the conveyance direction X to the second end opposite to the first end includes the range in the conveyance direction X where the heater 43 is arranged.

[0087] The image forming apparatus 202 of the second modification can provide the same effects as the image forming apparatus 1 of this embodiment. Furthermore, the second heat conducting member 46 can be supported in the portion between the recess 461 and the second recess 462 .

[0088] like Figure 8 As shown in the heater unit 106 of the image forming apparatus 203 of the third modified example, in the heater unit 37 of this embodiment, the first heat-conducting member 45 and the second heat-conducting member 46 may be interchanged in the first direction Z. Specifically, in the heater unit 106, the heater 43, the substrate 44, the second heat-conducting member 46, and the first heat-conducting member 45 are arranged in this order from the heated region 361 side. The recessed portion 461 of the second heat-conducting member 46 is located on the outer surface of the second heat-conducting member 46 on the side facing the substrate 44.

[0089] The image forming apparatus 203 according to the third modification can also achieve the same effects as those of the image forming apparatus 1 according to the present embodiment.

[0090] You can also Figure 9 Like the heater unit 111 of the image forming apparatus 204 of the fourth modification shown, the heater unit 106 of the image forming apparatus 203 of the third modification includes a third heat-conducting member 102 disposed between the substrate 44 and the second heat-conducting member 46 .

[0091] The image forming apparatus 204 according to the fourth modification includes the third heat conducting member 102. Therefore, when the heater 43 is pressed by the pressure roller 31 via the cylindrical body 36, for example, deformation of the heater 43, substrate 44, second heat conducting member 46, and first heat conducting member 45 can be more reliably suppressed.

[0092] It should be noted that, in the present embodiment, the heater units 37 , 101 , 104 , 106 , and 111 may not include the substrate 44 .

[0093] The thickness t2 of the second heat conducting member 46 may be less than or equal to the thickness t1 of the first heat conducting member 45 .

[0094] The recessed portion 461 does not need to be formed so as to encompass the range where the heater 43 is disposed in the axial direction Y. For example, the recessed portion 461 may be formed so as to encompass only a portion of the range where the heater 43 is disposed in the axial direction Y. The recessed portion 461 may also be formed only in a portion of the second heat conducting member 46 in the axial direction Y.

[0095] The first heat conducting member 45 and the second heat conducting member 46 do not need to be in the form of a flat plate with the thickness direction being the first direction Z. For example, the first heat conducting member and the second heat conducting member may be formed in the form of a rectangular parallelepiped.

[0096] According to at least one of the embodiments described above, the time until printing starts can be shortened by providing the recessed portion 461 formed in the second heat-conductive member 46 .

[0097] While several embodiments of the present invention have been described, these embodiments are provided for illustrative purposes only and are not intended to limit the scope of the invention. These embodiments may be implemented in various other forms and may be omitted, replaced, or modified without departing from the spirit of the invention. These embodiments and their variations are intended to be within the scope and spirit of the invention and, likewise, within the scope of the invention set forth in the claims and their equivalents.

Claims

1. An image forming apparatus comprising: an image forming unit that forms an image on a sheet; and Fixing device, The fixing device comprises: cylindrical body; a heater located in the cylindrical body, facing a heated area that is a portion of a circumference of the cylindrical body, and heating the heated area; a first heat conducting member located on an opposite side of the heated area relative to the heater, wherein the heat conductivity of the first heat conducting member in a direction perpendicular to the first direction is greater than the heat conductivity of the first heat conducting member in a first direction opposite to the heated area and the heater; as well as The second heat conducting member is arranged on the side of the first heat conducting member opposite to the heater and has a recess and a second recess on an outer surface facing the first heat conducting member. The recessed portion and the second recessed portion are arranged with a space between them in the conveying direction of the sheet.

2. The image forming apparatus according to claim 1, wherein The length of the second heat conducting member in the first direction is longer than the length of the first heat conducting member in the first direction.

3. The image forming apparatus according to claim 1 or 2, wherein: The image forming apparatus includes the recessed portion so as to include a range in which the heater is arranged in the axial direction of the cylindrical body.

4. The image forming apparatus according to claim 1 or 2, wherein: The recessed portion penetrates the second heat conducting member in the axial direction of the cylindrical body.

5. The image forming apparatus according to claim 3, wherein The recessed portion penetrates the second heat conducting member in the axial direction of the cylindrical body.

6. The image forming apparatus according to claim 1 or 2, wherein: The image forming apparatus includes a third heat-conducting member located between the first heat-conducting member and the second heat-conducting member.

7. The image forming apparatus according to claim 3, wherein: The image forming apparatus includes a third heat-conducting member located between the first heat-conducting member and the second heat-conducting member.

8. The image forming apparatus according to claim 4, wherein: The image forming apparatus includes a third heat-conducting member located between the first heat-conducting member and the second heat-conducting member.

9. The image forming apparatus according to claim 5, wherein: The image forming apparatus includes a third heat-conducting member located between the first heat-conducting member and the second heat-conducting member.

10. The image forming apparatus according to claim 1 or 2, wherein: The recessed portion is formed so as to include a range in which the heater is arranged in a conveying direction of the sheet.

Images