Heating device, fixing device, image forming apparatus

Abstract

To provide a nip forming member that can assemble a high thermal conduction member and a substrate with a simple configuration.SOLUTION: A nip forming member 24 comprises: a substrate 41; a high thermal conduction member 42 that has a higher thermal conductivity than that of the substrate 41; and an attachment member 43 that is provided in an elastically deformable manner and attached to the high thermal conduction member 42 with the substrate 41 therebetween, and the nip forming member is in contact with a fixing belt 20 from the inside thereof and forms a nip part between a pressure roller 22 and the nip forming member with the fixing belt 20 therebetween. With the elastic deformation of the attachment member 43, the attachment member 43 is arranged between one side and the other side of the high thermal conduction member 42, and thereby the attachment member 43 is attached to the high thermal conduction member 42.SELECTED DRAWING: Figure 4

Description

[Technical field]

[0001] The present invention , Canada The present invention relates to a heating device, a fixing device and an image forming apparatus. [Background technology]

[0002] A fixing device having a fixing belt as a belt member is provided with a nip forming member that comes into contact with the fixing belt from the inside thereof and forms a fixing nip between the fixing belt and an opposing member such as a pressure roller via the fixing belt.

[0003] A known configuration for this nip forming member is to provide a highly heat conductive member with high thermal conductivity on the fixing belt side to uniformize the temperature in the longitudinal direction of the fixing belt. The highly heat conductive member is fixed integrally to the base material of the nip forming member to prevent the highly heat conductive member from shifting or falling off.

[0004] For example, in the fixing device of Patent Document 1 (JP 2017-181841 A), a plate-shaped nip member, a leaf spring, and a sliding sheet covering the front and back of these are provided, and the sliding sheet, nip member, and leaf spring are integrally secured by screws via a pressing member on the back side of the sliding sheet.

[0005] However, the method of fixing the fixing belt by using screws has problems such as an increase in the number of parts and generation of chips from the screws that can damage the fixing belt. Summary of the Invention [Problem to be solved by the invention]

[0006] The highly thermally conductive member and the base material can be assembled using a simple structure. heating device The objective is to provide the following. [Means for solving the problem]

[0007] In order to solve the above problems, the present invention provides A heating device including a nip forming member, a rotatable belt member, and an opposing member, the nip forming member beinga base material, a high thermal conductivity member having a thermal conductivity higher than that of the base material, and an attachment member provided to be elastically deformable and attached to the high thermal conductivity member; The nip forming member The belt member is abutted against the inside of the belt member, and the belt member is The above Forming a nip between the opposing member death, The mounting member is attached to the high thermal conductivity member by sandwiching the base material between the mounting member and the high thermal conductivity member due to elastic deformation of the mounting member. The nip forming member is further provided with a support member for supporting the nip forming member, the base material has a positioning protrusion, the mounting member has a positioning hole into which the positioning protrusion is inserted to position the mounting member relative to the base material, and the positioning protrusion also serves to position the base material relative to the support member. It is characterized by: Effect of the Invention

[0008] According to the present invention, the highly thermally conductive member and the base material can be assembled with a simple structure. [Brief description of the drawings]

[0009] [Figure 1] FIG. 1 is a schematic diagram of an image forming apparatus. [Diagram 2] 1 is a side cross-sectional view showing a schematic configuration of a fixing device according to an embodiment of the present invention. [Diagram 3] FIG. 2 is an exploded perspective view showing each member that constitutes the nip forming member. [Figure 4] FIG. 4 is a perspective view showing an attachment member assembled to a nip forming member. [Diagram 5] FIG. 2 is a side cross-sectional view of a nip forming member. [Figure 6] 5 is a side cross-sectional view showing the assembly of the nip forming member. FIG. [Figure 7] 5 is a side cross-sectional view showing the assembly of the nip forming member. FIG. [Figure 8] 5 is a side cross-sectional view showing the assembly of the nip forming member. FIG. [Figure 9] FIG. 11 is a side cross-sectional view showing a nip formation member according to a different embodiment from the above. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0010] Hereinafter, an embodiment of the present invention will be described with reference to the drawings. In the following description, a fixing device that heats and fixes toner on a sheet of paper as a recording medium will be described as an example of a heating device having a nip forming member. Note that in each drawing, the same or corresponding parts are given the same reference numerals, and duplicated descriptions will be appropriately simplified or omitted.

[0011] An image forming section 2 is disposed in the center of the color image forming apparatus 1 shown in Fig. 1. Four process units 9Y, 9M, 9C, and 9Bk are detachably provided in the image forming section 2. Each process unit 9Y, 9M, 9C, and 9Bk has the same configuration except that it contains a developer of a different color, yellow (Y), magenta (M), cyan (C), or black (Bk), which corresponds to the color separation components of a color image.

[0012] Specifically, each process unit 9 includes a photoconductor drum 10, a charging roller 11, and a developing device 12 having a developing roller. The photoconductor drum 10 is a drum-shaped rotating body capable of carrying toner as a developer on its surface. The charging roller 11 uniformly charges the surface of the photoconductor drum 10. The developing roller supplies toner to the surface of the photoconductor drum 10.

[0013] The exposure unit 3 is disposed below the process unit 9. The exposure unit 3 emits laser light based on image data.

[0014] The transfer unit 4 is disposed above the image forming unit 2. The transfer unit 4 is composed of a drive roller 14, a driven roller 15, an intermediate transfer belt 16, a primary transfer roller 13, and the like. The intermediate transfer belt 16 is an endless belt member, and is stretched around the drive roller 14 and the driven roller 15 so as to be able to rotate. The primary transfer roller 13 is disposed in a position facing the photosensitive drum 10 of each process unit 9 with the intermediate transfer belt 16 therebetween. Each primary transfer roller 13 presses the inner peripheral surface of the intermediate transfer belt 16 at its respective position. A primary transfer nip is formed at a location where the portion of the intermediate transfer belt 16 pressed by the primary transfer roller 13 comes into contact with each photosensitive drum 10.

[0015] The image forming unit 2 and the transfer unit 4 constitute an image forming means in the image forming apparatus 1 that forms an image on a sheet.

[0016] A secondary transfer roller 17 is disposed at a position facing the drive roller 14 with the intermediate transfer belt 16 in between. The secondary transfer roller 17 presses against the outer circumferential surface of the intermediate transfer belt 16, and a secondary transfer nip is formed at the location where the secondary transfer roller 17 and the intermediate transfer belt 16 come into contact with each other.

[0017] The paper feed section 5 is made up of a paper feed cassette 18, a paper feed roller 19, etc. The paper feed cassette 18 is located at the bottom of the image forming apparatus 1, and stores paper P as a recording medium. The paper feed roller 19 conveys the paper P stored in the paper feed cassette 18.

[0018] The conveying path 7 is a transport path for transporting the paper P discharged from the paper supply section 5, and in addition to a pair of registration rollers 30, pairs of conveying rollers are appropriately arranged along the conveying path 7 until the paper discharge section 8 described later.

[0019] The fixing device 6 includes a fixing belt 21, a pressure roller 22, etc. The fixing belt 21 is heated by a heating member. The pressure roller 22 applies pressure to the fixing belt 21.

[0020] The paper discharge section 8 is provided at the most downstream side of the transport path 7 of the image forming apparatus 1. A pair of paper discharge rollers 31 and a paper discharge tray 32 are arranged in this paper discharge section 8. The paper discharge rollers 31 discharge the paper P to the outside of the housing of the image forming apparatus 1. The paper discharge tray 32 stores the discharged paper P.

[0021] Hereinafter, the basic operation of the image forming apparatus 1 will be described with reference to FIG.

[0022] In the image forming apparatus 1, when an image forming operation is started, an electrostatic latent image is formed on the surface of the photoconductor drum 10 of each process unit 9Y, 9C, 9M, 9Bk. The image information exposed to each photoconductor drum 10 by the exposure unit 3 is monochromatic image information obtained by decomposing a desired full-color image into color information of yellow, cyan, magenta, and black. An electrostatic latent image is formed on each photoconductor drum 10. The toner stored in each developing device 12 is supplied to the photoconductor drum 10 by a drum-shaped developing roller, and the electrostatic latent image on the photoconductor drum 10 is visualized as a toner image (developer image), which is a visible image.

[0023] In the transfer unit 4, the intermediate transfer belt 16 is driven to run in the direction of arrow A in the figure by the rotational drive of the drive roller 14. A constant voltage or constant current controlled voltage of a polarity opposite to the charge polarity of the toner is applied to each primary transfer roller 13. This forms a transfer electric field in the primary transfer nip, and the toner images formed on each photoconductor drum 10 are transferred in sequence onto the intermediate transfer belt 16 in the primary transfer nip, overlapping each other.

[0024] Meanwhile, when the image forming operation is started, at the bottom of the image forming apparatus 1, the paper feed roller 19 of the paper feed unit 5 is rotated and driven to send the paper P stored in the paper feed cassette 18 to the conveying path 7. The paper P sent to the conveying path 7 is sent to the secondary transfer nip between the secondary transfer roller 17 and the drive roller 14 at a timing measured by the registration roller 30. At this time, a transfer voltage of a polarity opposite to the toner charge polarity of the toner image on the intermediate transfer belt 16 is applied, and a transfer electric field is formed in the secondary transfer nip. The toner image on the intermediate transfer belt 16 is transferred onto the paper P all at once by the transfer electric field formed in the secondary transfer nip.

[0025] The paper P onto which the toner image has been transferred is transported to the fixing device 6, where the paper P is heated and pressed by the fixing belt 21 and the pressure roller 22, thereby fixing the toner image onto the paper P. Then, the paper P onto which the toner image has been fixed is separated from the fixing belt 21, and is transported further downstream by the pair of transport rollers. Then, in the paper discharge section 8, the paper P is discharged by the paper discharge rollers 31 onto the paper discharge tray 32.

[0026] The above description is of the image forming operation when forming a full-color image on paper P, but it is also possible to form a monochrome image using any one of the four process units 9Y, 9C, 9M, 9Bk, or to form a two-color or three-color image using two or three process units 9.

[0027] Next, the basic structure of the fixing device 6 will be described with reference to FIG. As shown in Fig. 2, the fixing device 6 includes a fixing belt 21 as a belt member (or fixing member), a pressure roller 22 as an opposing member, a halogen heater 23 as a heating member, a nip forming member 24, a stay 25 as a supporting member, a pressure means, and the like. The fixing belt 21 is rotatably provided. The pressure roller 22 is rotatably provided facing the fixing belt 21. The halogen heater 23 heats the fixing belt 21. The nip forming member 24 is disposed inside the fixing belt 21. The stay 25 supports the nip forming member 24 by contacting it from its rear side. The pressure means presses the pressure roller 22 against the fixing belt 21.

[0028] The fixing belt 21, pressure roller 22, halogen heater 23, nip forming member 24, and stay 25 extend in a direction perpendicular to the plane of the drawing in Fig. 2. Hereinafter, this direction will be referred to as the longitudinal direction of the fixing belt 21, etc. This longitudinal direction is also the width direction of the paper P passed through the fixing device 6.

[0029] The fixing belt 21 is made of a thin, flexible endless belt member (including a film). More specifically, the fixing belt 21 is made of a base material provided on the inner periphery and a release layer provided on the outer periphery. An elastic layer made of a rubber material such as silicone rubber, foamed silicone rubber, or fluororubber may be interposed between the base material and the release layer. The base material of the fixing belt 21 is made of a metal material such as nickel or SUS, or a resin material such as polyimide (PI). The release layer of the fixing belt 21 is made of tetrafluoroethylene-perfluoroalkylvinylether copolymer (PFA), polytetrafluoroethylene (PTFE), or the like.

[0030] The pressure roller 22 is composed of a core metal 22a, an elastic layer 22b provided on the surface of the core metal 22a, and a release layer 22c provided on the surface of the elastic layer 22b. The elastic layer 22b is made of foamed silicone rubber, silicone rubber, fluororubber, or the like. The release layer 22c is made of PFA, PTFE, or the like. The pressure roller 22 is pressed toward the fixing belt 21 by a pressing means and abuts against the nip forming member 24 via the fixing belt 21. At the location where the pressure roller 22 and the fixing belt 21 are in pressure contact with each other, the elastic layer 22b of the pressure roller 22 is crushed to form a fixing nip N as a nip portion of a predetermined width. The pressure roller 22 is configured to be rotated by a driving source such as a motor provided in the printer body. When the pressure roller 22 is rotated, the driving force is transmitted to the fixing belt 21 at the fixing nip N, and the fixing belt 21 is rotated by the fixing nip N.

[0031] In this embodiment, the pressure roller 22 is a solid roller, but it may be a hollow roller. In that case, a heating source such as a halogen heater may be disposed inside the pressure roller 22. If the pressure roller 22 does not have an elastic layer, the heat capacity is reduced and the fixing performance is improved, but when the unfixed toner is crushed and fixed, minute irregularities on the surface of the fixing belt 21 may be transferred to the image, causing uneven gloss in the solid part of the image. To prevent this, it is desirable to provide the pressure roller 22 with an elastic layer having a thickness of 100 μm or more. By providing the pressure roller 22 with an elastic layer having a thickness of 100 μm or more, the minute irregularities on the surface of the fixing belt 21 can be absorbed by the elastic deformation of the elastic layer. Therefore, it becomes possible to prevent uneven gloss in the image on the paper. The elastic layer 22b may be solid rubber, but if there is no heating source inside the pressure roller 22, sponge rubber may be used. Sponge rubber is more desirable because it has higher heat insulation and is less likely to take away heat from the fixing belt 21. Further, the fixing member and the opposing member are not limited to being pressed against each other, and may be simply in contact with each other without applying pressure.

[0032] Both ends of the halogen heater 23 are fixed to the side plates of the fixing device 6. The halogen heater 23 is configured to generate heat under output control by a power supply unit provided in the printer body, and the output control is performed based on the detection result of the surface temperature of the fixing belt 21 by a temperature sensor. By controlling the output of the heater 23 in this way, the temperature of the fixing belt 21 (fixing temperature) can be set to a desired temperature. In addition to the halogen heater, an IH heater, a resistance heating element, a carbon heater, or the like may be used as a heating member for heating the fixing belt 21.

[0033] The nip forming member 24 is fixed and supported from the rear side by a stay 25. This prevents the nip forming member 24 from being deflected by the pressure of the pressure roller 22, and ensures that a uniform nip width is obtained along the longitudinal direction. The detailed configuration of the nip forming member 24 will be described later.

[0034] The stay 25 contacts the nip forming member 24 from its rear side in the longitudinal direction, and supports the nip forming member 24 against the pressure force of the pressure roller 22. This makes it possible to suppress bending of the nip forming member 24 mainly in the longitudinal direction. To satisfy the function of preventing bending of the nip forming member 24, it is desirable to form the stay 25 from a metal material with high mechanical strength such as stainless steel or iron, but it is also possible to make the stay 25 from resin.

[0035] Furthermore, the fixing device 6 according to this embodiment is designed with various structural improvements to further improve energy saving performance and first print time. Specifically, the fixing belt 21 can be directly heated by the halogen heater 23 at a location other than the fixing nip N (direct heating method). In this embodiment, nothing is interposed between the halogen heater 23 and the left portion of the fixing belt 21 in FIG. 2, and radiant heat from the halogen heater 23 is directly applied to the fixing belt 21 at that portion.

[0036] To reduce the heat capacity of the fixing belt 21, the fixing belt 21 is made thinner and has a smaller diameter. Specifically, the thicknesses of the base material, elastic layer, and release layer constituting the fixing belt 21 are set in the ranges of 20 to 50 μm, 100 to 300 μm, and 10 to 50 μm, respectively, and the overall thickness is set to 1 mm or less. The diameter of the fixing belt 21 is set to 20 to 40 mm. To further reduce the heat capacity, it is preferable that the overall thickness of the fixing belt 21 is set to 0.2 mm or less, and more preferably to 0.16 mm or less. It is preferable that the diameter of the fixing belt 21 is set to 30 mm or less.

[0037] In this embodiment, the diameter of the pressure roller 22 is set to 20 to 40 mm, and the diameter of the fixing belt 21 and the diameter of the pressure roller 22 are configured to be equal. However, this is not limited to the above configuration. For example, the diameter of the fixing belt 21 may be smaller than the diameter of the pressure roller 22. In this case, the curvature of the fixing belt 21 at the fixing nip N becomes larger than the curvature of the pressure roller 22, so that the recording medium discharged from the fixing nip N is easily separated from the fixing belt 21.

[0038] Hereinafter, the basic operation of the fixing device according to this embodiment will be described with reference to FIG. When the power switch of the printer body is turned on, power is supplied to the halogen heater 23, and the pressure roller 22 starts to rotate clockwise (see arrow B1) in Fig. 2. As a result, the fixing belt 21 is rotated counterclockwise (see arrow B2) in Fig. 2 by the frictional force with the pressure roller 22.

[0039] Thereafter, the paper P carrying the unfixed toner image T by the image forming process described above is conveyed in the direction of arrow C1 in Fig. 2 while being guided by a guide plate, and is sent into the fixing nip N. Then, the toner image T is fixed onto the surface of the paper P by the heat of the fixing belt 21 heated by the halogen heater 23 and the pressure force between the fixing belt 21 and the pressure roller 22.

[0040] The paper P on which the toner image T has been fixed is conveyed out of the fixing nip N in the direction of the arrow C2 in Fig. 2. At this time, the leading edge of the paper P comes into contact with the leading edge of the separating member, so that the paper P is separated from the fixing belt 21. Thereafter, the separated paper P is discharged outside the machine by the paper discharge rollers, as described above, and is stocked in the paper discharge tray.

[0041] Next, a more detailed configuration of the nip formation member 24 will be described with reference to Figures 2 and 3. The direction of the double-headed arrow X in Figure 3 is the longitudinal direction of the nip formation member 24. The direction intersecting this longitudinal direction (particularly the direction perpendicular to the longitudinal direction in this embodiment) and different from the thickness direction of the nip formation member 24 is the lateral direction Y of the nip formation member 24.

[0042] 2 and 3, the nip formation member 24 includes a base material 41, a highly thermally conductive member 42, and an attachment member 43. The base material 41 and the highly thermally conductive member 42 extend in the longitudinal direction of the nip formation member 24.

[0043] The substrate 41 is made of a heat-resistant material, and examples of the material that can be used include inorganic materials such as ceramic, glass, and aluminum; rubbers such as silicone rubber and fluororubber; fluororesins such as PTFE (tetrafluoroethylene), PFA (tetrafluoroethylene-perfluoroalkoxyvinyl ether copolymer), ETFE (ethylene-tetrafluoroethylene copolymer), and FEP (tetrafluoroethylene-hexafluoropropylene copolymer); resins such as PI (polyimide), PAI (polyamideimide), PPS (polyphenylene sulfide), PEEK (polyether ether ketone), LCP (liquid crystal plastic, liquid crystal polymer), phenolic resin, nylon, and aramid, and combinations of these.

[0044] In this embodiment, the base material 41 is made of a liquid crystal polymer (LCP) that has excellent heat resistance and formability, and its thermal conductivity is set to, for example, 0.54 W / m·K.

[0045] Base material 41 has a positioning protrusion 41a at the center in the longitudinal direction thereof for positioning mounting member 43 relative to base material 41. Positioning protrusion 41a is a boss that protrudes toward stay 25 (left side in FIG. 2). Positioning protrusion 41a is inserted into stay 25, thereby positioning base material 41 (or nip forming member 24) relative to stay 25. For example, insertion of positioning protrusion 41a into a hole in stay 25 restricts movement of nip forming member 24 in the longitudinal and lateral directions relative to stay 25. In other words, nip forming member 24 is positioned relative to fixing device 9 in the longitudinal and lateral directions.

[0046] 3, in addition to positioning protrusion 41a, base material 41 has a plurality of protrusions 41b protruding toward stay 25. A plurality of protrusions 41b are arranged in the longitudinal direction of base material 41, and are provided in two rows in the lateral direction. Protrusions 41b abut against stay 25. This determines the position of nip forming member 24 relative to stay 25 in its thickness direction (left-right direction in FIG. 2).

[0047] 2, the base material 41 has a recess 41c on the side of the highly thermally conductive member 42. This reduces the contact area of ​​the base material 41 with the highly thermally conductive member 42, and reduces the amount of heat that flows from the fixing belt 21 to the base material 41 side via the highly thermally conductive member 42.

[0048] Highly thermally conductive member 42 is a member that comes into contact with fixing belt 21 from its inner circumferential surface side. Highly thermally conductive member 42 is made of a member having a higher thermal conductivity than base material 41. In this embodiment, aluminum is used as the material for highly thermally conductive member 42, and the thermal conductivity is set to about 236 W / m·K, for example. Alternatively, SUS (thermal conductivity of 16.7 to 20.9 W / m·K) or a copper-based material (thermal conductivity of 381 W / m·K, for example) may be used for highly thermally conductive member 42.

[0049] Next, a method for calculating the thermal conductivity will be described. When calculating the thermal conductivity, first, the thermal diffusivity of the object is measured, and then the thermal conductivity is calculated using the measured thermal diffusivity.

[0050] The thermal diffusivity was measured using a thermal diffusivity / thermal conductivity measuring device (product name: ai-Phase Mobile 1u, ai-Phase Corporation).

[0051] In order to convert the thermal diffusivity to thermal conductivity, the values ​​of density and specific heat capacity are required. A dry-type automatic density meter (product name: Accupyc 1330, manufactured by Shimadzu Corporation) was used to measure the density. A differential scanning calorimeter (product name: DSC-60, manufactured by Shimadzu Corporation) was used to measure the specific heat capacity, and sapphire was used as a reference material with a known specific heat capacity. In this example, the specific heat capacity was measured five times, and the average value at 50°C was used. If the density and specific heat capacity are ρ and C, respectively, the thermal conductivity λ can be obtained from the thermal diffusivity α obtained by the thermal diffusivity measurement by the following formula (1).

[0052]

number

[0053] Furthermore, by bringing the highly heat-conductive member 42 into contact with the fixing belt 21 over the entire length thereof, the heat of the fixing belt 21 can be transferred and made uniform in the lengthwise direction, thereby making it possible to suppress temperature unevenness in the fixing belt 21 over the lengthwise direction.

[0054] High thermal conductivity member 42 has bent portions 42a provided along the length of the member on both short sides of the member. In this embodiment, high thermal conductivity member 42 having bent portions 42a is formed by bending a metal plate on both short sides of the member (upper and lower sides in FIG. 2) in a direction substantially perpendicular to the short side of the member (leftward in FIG. 2, opposite to fixing nip N).

[0055] As shown in FIG. 3, the high thermal conductivity member 42 has insertion holes 42b1, 42b2 (see FIG. 5) on both sides in the short direction at the center of the longitudinal direction of both the bent portions 42a, 42a. The portion of the bent portion 42a where the insertion holes 42b1, 42b2 are provided has a shape that protrudes partially in the bending direction compared to the other portion of the bent portion 42a. Also, as shown in FIG. 3, the high thermal conductivity member 42 has, at both ends in the longitudinal direction, narrowed portions 42e whose width in the short direction becomes smaller toward the ends. The narrowed portions 42e restrict the longitudinal movement of the base material 41 relative to the high thermal conductivity member 42, but do not completely restrict the longitudinal movement, and the thermal expansion of the base material 41 in the longitudinal direction is permitted.

[0056] The mounting member 43 is provided so as to be elastically deformable. In this embodiment, the mounting member 43 is a leaf spring made of SUS.

[0057] The mounting member 43 has positioning holes 43a in which the positioning protrusions 41a of the base material 41 are positioned. The mounting member 43 also has insertion portions 43b1, 43b2 (see FIG. 5) on both ends.

[0058] FIG. 4 shows a perspective view of the nip forming member 24 with the mounting member 43 attached, and FIG. 5 shows a cross-sectional view. 4 and 5, mounting member 43 is attached to high thermal conductivity member 42 by inserting insertion portions 43b1, 43b2 into insertion holes 42b1, 42b2 of high thermal conductivity member 42, respectively. Mounting member 43 is attached to high thermal conductivity member 42 with base material 41 sandwiched between mounting member 43 and high thermal conductivity member 42. In this way, base material 41 can be held between high thermal conductivity member 42 and mounting member 43.

[0059] Furthermore, the length B of the mounting member 43 (more specifically, the length from the end of the insertion portion 43b1 to the end of the insertion portion 43b2, and particularly in this embodiment, the overall length B of the mounting member 43) is set to be larger than the gap C between the bent portions 42a in the portion where the insertion holes 42b1, 42b2 of the high thermal conductivity member 42 are provided. The mounting member 43 also has a bent portion 43c extending in a direction intersecting the extending direction of the mounting member 43 (in this embodiment, a direction perpendicular thereto, the left-right direction in FIG. 5). The bent portion 43c is a portion that an operator grips when mounting the mounting member 43 to the high thermal conductivity member 42, which will be described later.

[0060] 4, the positioning protrusion 41a of the base material 41 is inserted into the upper part of the positioning hole 43a of the mounting member 43. This positions the mounting member 43 with respect to the base material 41. The positioning hole 43a is provided not only in the portion where the positioning protrusion 41a is inserted, but also below the portion. By widening the range of the positioning hole 43a in this manner, the rigidity of the mounting member 43 can be reduced, making it easier for the mounting member 43 to deform elastically.

[0061] Next, a procedure for assembling the nip forming member 24 will be described.

[0062] First, as shown in Fig. 6, the base material 41 is placed in the recess between both bent portions 42a of the high thermal conductivity member 42. Then, as shown in Fig. 7, the mounting member 43 is brought close to the high thermal conductivity member 42 from above (see the direction of arrow D1) and inserted obliquely into the high thermal conductivity member 42 (see the direction of arrow D2). As a result, one insertion portion 43b1 is inserted into the insertion hole 42b1, and the positioning protrusion 41a of the base material 41 is inserted into the positioning hole 43a of the mounting member 43.

[0063] 8, with the insertion portion 43b1 inserted into the insertion hole 42b1, the mounting member 43 is elastically deformed and the other insertion portion 43b2 is inserted into the insertion hole 42b2. More specifically, using the portion where the insertion portion 43b1 abuts on the inner wall of the insertion hole 42b1 as a fulcrum, the worker applies force in the direction of arrow D3 to the insertion portion 43b2 side of the mounting member 43 (for example, by gripping the bent portion 43c and pushing it in the direction of arrow D3), thereby elastically deforming the mounting member 43 and inserting the insertion portion 43b2 into the insertion hole 42b2.

[0064] After inserting the insertion portion 43b2 into the insertion hole 42b2, the pressing force on the mounting member 43 is released, causing the mounting member 43 to elastically return to its original state. As a result, as shown in Fig. 5, the mounting member 43 is attached to the high thermal conductivity member 42, and the nip formation member 24 is assembled. Note that, although the above description has shown a case in which the insertion portion 43b1 is first inserted into the insertion hole 42b1 and then the insertion portion 43b2 is inserted into the insertion hole 42b2, this may be reversed.

[0065] As described above, in this embodiment, the mounting member 43 can be attached to the high thermal conductivity member 42 by the elastic deformation of the mounting member 43. More specifically, with one insertion portion 43b1 of the mounting member 43 inserted into the insertion hole 42b1, the other insertion portion 43b2 can be disposed inside the bent portion 42a. That is, the mounting member 43 can be disposed in the recess between both bent portions 42a of the high thermal conductivity member 42 (however, strictly speaking, the entire mounting member 43 is not necessarily disposed in the recess, and the end side of the insertion portion 43b1 may be disposed outside the recess via the insertion hole 42b1), and the other insertion portion 43b2 can be inserted into the insertion hole 42b2. Therefore, the mounting member 43 can be attached to the high thermal conductivity member 42 (nip forming member 24) with a simple configuration without using another member such as a screw fastener.

[0066] In a configuration in which mounting member 43 is attached to nip forming member 24 by screwing, or in a configuration in which base material 41 and high thermal conductivity member 42 are directly screwed together to fix them, there is a risk that chips generated by screwing or screws falling off from the female threads may damage fixing belt 21, causing abnormal images. In contrast, in this embodiment, mounting member 43 can be attached to high thermal conductivity member 42 without providing a separate member such as a screw, as described above, and damage to fixing belt 21 can be prevented. In addition, the number of parts in nip forming member 24 can be reduced.

[0067] By attaching the mounting member 43, the base material 41 and the high thermal conductivity member 42 can be assembled without falling off from each other, and the base material 41 and the high thermal conductivity member 42 can be positioned. Specifically, the positioning portion 41a of the base material 41 is fitted into the positioning hole 43a of the mounting member 43, so that the longitudinal movement of the base material 41 relative to the mounting member 43 is restricted. Furthermore, the movement of the insertion portions 43b1, 43b2 is restricted within the insertion holes 42b1, 42b2, so that the mounting member 43 is positioned in the longitudinal direction relative to the high thermal conductivity member 42. As a result, the base material 41 is positioned in the longitudinal direction relative to the high thermal conductivity member 42.

[0068] The base material 41 is held between the bent portions 42a of the high thermal conductivity member 42, and is positioned in the short-side direction. The inner wall portion constituting the positioning hole 43a of the mounting member 43 abuts against the positioning protrusion 41a of the base material 41, thereby restricting the downward movement of the mounting member 43 in FIG. 5 relative to the base material 41. This restricts the downward movement of the mounting member 43 in FIG. 5 relative to the high thermal conductivity member 42, and prevents the insertion portion 43b1 from falling off the insertion hole 42b1. The upper edge 43d (see FIG. 3) of the mounting member 43 abuts against the bent portion 42a of the high thermal conductivity member 42 from below, thereby restricting the upward movement of the mounting member 43 in FIG. 5 relative to the high thermal conductivity member 42. This prevents the insertion portion 43b2 from falling off the insertion hole 42b2.

[0069] Furthermore, the movement of insertion portions 43b1, 43b2 is restricted within insertion holes 42b1, 42b2, thereby restricting the movement of mounting member 43 in the thickness direction (left and right direction in FIG. 5) relative to high thermal conductivity member 42. Furthermore, the movement of base material 41 in the thickness direction is restricted by being sandwiched between mounting member 43 and high thermal conductivity member 42. As a result, the movement of base material 41 in the thickness direction relative to high thermal conductivity member 42 is restricted.

[0070] In this manner, in this embodiment, the base material 41 and the highly thermally conductive member 42 are positioned in each direction (longitudinal direction, lateral direction, thickness direction) by attaching the mounting member 43 to the highly thermally conductive member 42, but the base material 41 and the highly thermally conductive member 42 are not completely fixed to each other. This makes it possible to prevent deformation of the base material 41 and the highly thermally conductive member 42, such as warping, due to thermal expansion. In other words, the base material 41 and the highly thermally conductive member 42 are made of different materials and have different thermal expansion coefficients, and therefore the amount of deformation due to heat transfer from the fixing belt 21 is also different. Therefore, for example, if the base material 41 is fixed to the highly thermally conductive member 42 by screwing or adhesive, the difference in the thermal expansion coefficient between the two components causes deformation, such as warping, but this embodiment makes it possible to prevent such deformation of the member.

[0071] 5, by setting the length B from the end of insertion portion 43b1 to the end of insertion portion 43b2 to be greater than the gap C, the mounting member 43 can be easily attached to the high thermal conductivity member 42 by elastic deformation when the mounting member 43 is attached, and after attachment, as described above, the insertion portions 43b1, 43b2 do not easily come off from the insertion holes 42b1, 42b2. In other words, a configuration can be achieved in which the mounting member 43 does not easily come off from the high thermal conductivity member 42, and the base material 41 and the high thermal conductivity member 42 are assembled without falling off from each other.

[0072] Furthermore, in this embodiment, as described above, the positioning protrusion 41a of the base material 41 can position the base material 41 relative to the highly heat conductive member 42 via the mounting member 43, and can also position the base material 41 relative to the stay 25. In other words, one positioning protrusion 41a can position the base material 41 relative to the highly heat conductive member 42 and position the nip forming member 24 relative to the stay 25, so that a simple configuration can be realized and the positioning accuracy of each member can be improved. Furthermore, by positioning the highly heat conductive member 42 of the nip forming member 24 relative to the stay 25 in the longitudinal direction, the heat conduction efficiency can be improved at the target position of the fixing belt 21. Furthermore, by positioning the nip forming member 24 relative to the stay 25 in the longitudinal direction, the fixing nip N can be formed at the target position of the fixing belt 21.

[0073] Although an embodiment of the present invention has been described above, the present invention is not limited to the above-described embodiment, and it goes without saying that various modifications can be made without departing from the gist of the present invention.

[0074] FIG. 9 shows a nip formation member 24 having a configuration in which the shape of the base material 41 is different from that of the above embodiment. As shown in FIG. 9, the base material 41 of this embodiment has a smaller contact area with the highly thermally conductive member 42. Specifically, the base material 41 has a plurality of recesses 41c on the highly thermally conductive member 42 side, and the contact area with the highly thermally conductive member 42 on the fixing belt 21 side is reduced. The base material 41 is also configured to have a smaller width in the short side direction (the vertical direction in FIG. 9) than the highly thermally conductive member 42, and a gap D is provided between the highly thermally conductive member 42 and both sides of the short side direction of the base material 41. This makes it possible to minimize the amount of heat flowing from the fixing belt 21 to the base material 41 via the highly thermally conductive member 42. In other words, the fixing device 6 can efficiently heat the fixing belt 21.

[0075] The image forming apparatus according to the present invention is not limited to the color image forming apparatus shown in FIG. 1, but may be a monochrome image forming apparatus, a copying machine, a printer, a facsimile, or a combination machine of these.

[0076] Examples of recording media include paper P (plain paper), as well as cardboard, postcards, envelopes, thin paper, coated paper (coated paper, art paper, etc.), tracing paper, OHP sheets, plastic film, prepreg, copper foil, and the like.

[0077] Furthermore, the present invention is not limited to the fixing device described in the above embodiment, but can also be applied to a drying device that dries ink applied to paper, and further to a nip forming member provided in a heating device such as a laminator that thermocompresses a film as a covering member onto the surface of a sheet such as paper, or a heat sealer that thermocompresses the seal portion of a packaging material. By applying the present invention to such devices, a configuration can be achieved in which a highly thermally conductive member and a substrate can be assembled with a simple configuration. [Explanation of symbols]

[0078] 1. Image forming device 6 Fixing device (heating device) 21 Fixing belt (belt member or fixing member) 22 Pressure roller (opposing member) 24 Nip forming member 25 Stay (support member) 41 Base material 41a Positioning protrusion 42 High thermal conductivity materials 42b1, 42b2 Insertion holes 43 Mounting material 43a Positioning hole 43b1, 43b2 Insertion part N Fixing nip (nip part) X: Longitudinal direction of nip forming member Y: Short side direction of nip forming member [Prior art documents] [Patent documents]

[0079] [Patent Document 1] JP 2017-181841 A

Claims

1. A nip forming member, A rotatable belt member; A heating device comprising: The nip forming member is A substrate; A highly thermally conductive member having a thermal conductivity higher than that of the base material; a mounting member that is elastically deformable and that is attached to the high thermal conductivity member; the nip forming member contacts the belt member from an inner side thereof to form a nip portion between the belt member and the opposing member, The mounting member is attached to the high thermal conductivity member by sandwiching the base material between the mounting member and the high thermal conductivity member due to elastic deformation of the mounting member, A support member for supporting the nip forming member is further provided. The base material has a positioning protrusion, the mounting member has a positioning hole into which the positioning protrusion is inserted to position the mounting member relative to the base material; A heating device, characterized in that the positioning protrusion also serves to position the base material relative to the support member.

2. The high thermal conductivity member has a pair of insertion holes on both sides thereof, The mounting member has a pair of insertion portions on both sides thereof, The heating device according to claim 1 , wherein the attachment member is attached to the highly thermally conductive member by inserting the insertion portion into the insertion hole.

3. 3. The heating device according to claim 1, wherein the mounting member is a leaf spring.

4. a fixing member as the belt member, 4. The heating device according to claim 1, which is a fixing device for fixing toner onto a recording medium by heat.

5. 5. An image forming apparatus comprising the fixing device according to claim 4.

Images