Fixing apparatus and image forming apparatus

Abstract

To provide a fixing device that can prevent abnormal deformation of a reflecting member and prevent an abnormal high temperature of the reflecting member, and an image forming apparatus.SOLUTION: A fixing device 40 comprises: a rotating fixing member such as a fixing belt; a pressure member such as a pressure roller that is in contact with an outer peripheral surface of the fixing member to form a nip part and applies pressure to a recording material passing through the nip part; and heat sources that are arranged inside the fixing member. The fixing device further comprises a reflecting member such as a reflector in which a reflecting part reflecting radiation heat radiated from the heat sources toward an inner peripheral surface of the fixing member and a pressure receiving part 48b receiving the pressure applied by the pressure member through the fixing member are integrated with each other or thermally connected with each other. The pressure receiving part 48b extends from one end to the other end of the fixing member, and the pressure receiving part 48b is provided with slits 48c.SELECTED DRAWING: Figure 6

Description

【Technical Field】 【0001】 The present invention relates to a fixing device and an image forming apparatus. 【Background Art】 【0002】 Conventionally, a fixing device including a rotating fixing member, a pressing member that presses a recording material passing through a nip portion formed by contacting the outer peripheral surface of the fixing member, and a heat source disposed inside the fixing member is known. 【0003】 Patent Document 1 describes, as the above fixing device, a first reflecting member that reflects radiant heat of a first heat source having a heat generating region at the axial center to the fixing member, and a second reflecting member that reflects radiant heat of a second heat source having a heat generating region at the axial end to the fixing member. Each reflecting member has a reflecting portion that reflects the radiant heat radiated from the heat source toward the inner peripheral surface of the fixing member, and a pressure receiving portion that receives the pressing force of the pressing member via the fixing member, and it is described that the heat of the heat source absorbed by the reflecting portion is transferred to the fixing member by the pressure receiving portion, thereby improving the thermal efficiency. 【0004】 Further, Patent Document 1 describes a device example in which the pressure receiving portion of each reflecting member extends from one end side to the other end side of the fixing member, and a device example in which the pressure receiving portion of the first reflecting member is at the axial center and the pressure receiving portions of the second reflecting members are provided at both axial ends. 【Summary of the Invention】 【Problems to be Solved by the Invention】 【0005】 However, in the configuration of Patent Document 1, there is a possibility that either abnormal deformation of the reflecting member or abnormal high temperature of the reflecting member cannot be suppressed. 【Means for Solving the Problems】 【0006】 To solve the above-mentioned problems, the present invention provides a fixing device comprising a rotating fixing member, a pressing member for pressing a recording material passing through a nip portion formed in contact with the outer circumferential surface of the fixing member, and a heat source disposed inside the fixing member, wherein the fixing device has a reflective portion that reflects radiant heat emitted from the heat source toward the inner circumferential surface of the fixing member and a pressure receiving portion that receives the pressing force of the pressing member via the fixing member, either integrally or thermally connected, and the pressure receiving portion extends from one end to the other end of the fixing member. Formed from a single continuous member Furthermore, the pressure receiving portion is characterized by having a notch provided. [Effects of the Invention] 【0007】 According to the present invention, abnormal deformation of the reflective member can be suppressed, and abnormal high temperatures of the reflective member can be suppressed. [Brief explanation of the drawing] 【0008】 [Figure 1] A schematic diagram of the image forming apparatus according to this embodiment. [Figure 2] A schematic diagram of the fixing device in this embodiment. [Figure 3] A perspective view showing the reflector, nip-forming member, and fixing stay. [Figure 4] A schematic diagram of a conventional fixing device. [Figure 5] A schematic diagram showing other configuration examples of the fixing device. [Figure 6] A schematic perspective view showing multiple notches in the pressure receiving section. [Figure 7] A schematic diagram showing the formation locations of multiple incisions. [Figure 8] This figure shows the axial heat transfer in the pressure receiving section and the temperature distribution on the fixing belt surface when there is no notch and when there is a notch. [Modes for carrying out the invention] 【0009】 The following describes an embodiment in which the present invention is applied to a laser printer (hereinafter referred to as "printer"), which is an electrophotographic image forming apparatus. Figure 1 is a schematic diagram of the image forming apparatus 1 of this embodiment. This image forming apparatus 1 includes an image forming unit 100 that forms an image on a paper P, which is a recording material. The image forming unit 100 is a tandem type image forming apparatus in which image forming units 10Y, 10M, 10C, and 10K for each color (yellow (Y), magenta (M), cyan (C), and black (K)) are arranged along the rotational direction of an intermediate transfer belt 20, which serves as an intermediate transfer body. Each image forming unit 10Y, 10M, 10C, and 10K is equipped with a photoreceptor 11Y, 11M, 11C, and 11K, respectively, which serves as a latent image carrier. 【0010】 Furthermore, each image-forming unit 10Y, 10M, 10C, 10K is equipped with a charging device as a charging means, an optical writing device 9 as an electrostatic latent image formation means, and a developing device as a developing means, around the photoreceptor 11Y, 11M, 11C, 11K. In addition, a primary transfer device as a primary transfer means and a cleaning device as a cleaning means are also provided around the photoreceptor 11Y, 11M, 11C, 11K. The charging device uniformly charges the surface of the photoreceptor to a predetermined potential, and the optical writing device 9 exposes the photoreceptor surface, which has been uniformly charged by the charging device, according to the image information and writes an electrostatic latent image. The developing device creates a toner image by a developing process that deposits toner of each color (Y, M, C, K) onto the electrostatic latent image on the photoreceptor. The primary transfer device transfers the toner image on the photoreceptor onto the intermediate transfer belt 20, and the cleaning device cleans the photoreceptor by removing any remaining toner. 【0011】 The toner images of each color formed on each photoreceptor 11Y, 11M, 11C, and 11K are transferred by the primary transfer device onto the intermediate transfer belt 20 so that they overlap each other, and a color toner image is formed on the intermediate transfer belt 20. The color toner image on the intermediate transfer belt 20 is transported to the region opposite the secondary transfer device 30 (secondary transfer region) as the intermediate transfer belt 20 rotates. 【0012】 Meanwhile, a paper feed cassette 60, which serves as a paper feed unit for feeding the paper P to be held, is located below the image forming unit 100. One sheet of paper P is fed from the paper feed cassette 60 by a pickup roller 61. Then, the paper P is transported along the transport path to the secondary transfer area by a pair of registration rollers 62. 【0013】 The color toner image on the intermediate transfer belt 20 is transferred in the secondary transfer region to the paper P, which is transported by the registration roller pair 62 at a predetermined timing, by the secondary transfer device 30. The paper P on which the color toner image has been formed is then transported to the fixing device 40, which acts as a fixing means, and the color toner image is fixed onto the paper P by the action of heat and pressure. After fixing, the paper P is transported along the transport path and discharged into the paper output tray 50 by the paper output roller 63. 【0014】 Figure 2 is a schematic diagram of the fixing device 40 in this embodiment. The fixing device 40 comprises a pressure roller 41 which is a pressurizing member, a fixing belt 42 which is a fixing member, and a heat source 43 (a halogen heater in the example shown in the figure), and performs fixing by heating and pressurizing. A nip-forming member 45, held by a fixing stay 44 which is a stay member, is positioned within the fixing belt 42. 【0015】 The nip-forming member 45 consists of a heat-distributing member 45a, which is a sliding member and heat-transferring member positioned on the nip surface, and a resin pad 45b that supports it. One of the roles of the resin pad 45b is heat insulation, which suppresses heat absorption by the fixing belt 42 to the fixing stay 44 via the nip-forming member 45, thereby suppressing the increase in warm-up time and TEC value. The heat-distributing member 45a is, for example, a pad shape that extends in the width direction of the fixing belt 42. This heat-distributing member 45a is positioned to average the axial temperature of the fixing belt. That is, it removes heat from areas of the fixing belt 42 where the temperature is high and moves the removed heat to areas of the fixing belt 42 where the temperature is low, thereby equalizing the axial temperature of the fixing belt 42. 【0016】 In the configuration of FIG. 2, the shape of the nip portion is flat, but it may also be concave or other shapes. By forming a concave nip, the discharge direction of the leading edge of the paper becomes closer to the pressure roller, and the separation property with respect to the fixing belt 42 of the paper is improved, so that the occurrence of jams is suppressed. 【0017】 The soaking member 45a is a metal member such as aluminum or copper with high thermal conductivity having a thermal conductivity of 50 [W / m·K] or more, and a coating excellent in sliding performance is applied to the surface of the soaking member 45a. Examples of the coating material include resin-based ones such as polyimide resin, fluororesin, polyphenylene sulfide resin, or saturated polyester resin. Or, glass fiber, carbon, graphite, fluorinated graphite, carbon fiber, molybdenum disulfide, fluororesin, etc. may be mixed into such a resin-based coating material. 【0018】 Also, metal-based materials can be used as the coating material. Examples of the metal-based coating material include molybdenum disulfide, nickel, composite plating of nickel and fluororesin, etc. Also, examples of the metal-based coating material include anodized aluminum or anodized aluminum impregnated with resin or metal. Also, ceramics can be used as the coating material. Examples of the ceramics used as the coating material include silicon carbide ceramics, silicon nitride ceramics, alumina ceramics, and those mixed with molybdenum disulfide, fluororesin, etc. 【0019】 Also, it is effective to form an anodized layer on the surface layer of the soaking member 45a formed of aluminum or an aluminum alloy, and fill molybdenum disulfide generated by secondary electrolysis into the micropores of the anodized layer from the deepest part to the outermost surface of the micropores. 【0020】 The pressure roller 41 has a silicone rubber layer provided on the outer periphery of a metal roller, and a release layer (PFA or PTFE layer) is provided on the surface of the silicone rubber layer to obtain release properties. Further, the pressure roller 41 is pressed against the fixing belt side by a spring or the like, and the rubber layer is compressed and deformed to have a predetermined nip width. 【0021】 The driving force of the pressure roller 41 is transmitted via gears from a driving source such as a motor provided in the image forming apparatus and rotates. The fixing belt 42 is rotated in a following manner by the driving force being transmitted from the pressure roller 41 at the nip portion. 【0022】 The pressure roller 41 may be a solid roller, but a hollow one is preferable because its heat capacity is smaller. Further, the pressure roller 41 may have a heating source such as a halogen heater. The silicone rubber layer may be solid rubber, but when there is no heater inside the pressure roller, sponge rubber may be used. Sponge rubber is more desirable because its heat insulation property is enhanced and it is difficult for the heat of the fixing belt to be taken away. 【0023】 The fixing belt 42 is an endless belt (or film) having a metal belt such as nickel or SUS or a resin material such as polyimide as a base material. The surface layer of the fixing belt 42 has a release layer such as a PFA or PTFE layer to provide release properties so that toner does not adhere. 【0024】 An elastic layer formed of a silicone rubber layer or the like may be provided between the base material of the fixing belt 42 and the release layer. When there is no silicone rubber layer, the heat capacity becomes small and the fixing property is improved, but when fixing an unfixed image by compressing it, there is a problem that fine irregularities on the belt surface are transferred to the image and traces like orange peel remain on the solid portion of the image. To improve this, it is necessary to provide a silicone rubber layer of 100 μm or more. Due to the deformation of the silicone rubber layer, fine irregularities are absorbed and the orange peel image is improved. 【0025】 The fixing stay 44 is a hollow, pipe-shaped metal body made of aluminum, iron, stainless steel, or other metal. In this embodiment, the fixing stay 44 is rectangular, but it may have other cross-sectional shapes. The pressure roller 41 prevents the nip forming member 45 from bending, ensuring a uniform nip width in the axial direction. 【0026】 Two heat sources are provided inside the fixing belt 42 to raise its temperature. In this embodiment, heat source 43 is a halogen heater, and the fixing belt 42 is directly heated from the inner circumference by radiant heat from heat source 43. Here, heat source 43 only needs to be able to heat the fixing belt 42, and may be an IH coil, a resistance heating element, a carbon heater, etc. 【0027】 Furthermore, a reflector 48 is positioned within the fixing belt 42 as a reflective element to reflect heat back towards the fixing belt in order to minimize the loss of radiant heat from the heat source 43. The reflector 48 is made of high-purity aluminum as a base material, with multiple reflective or protective films formed on the surface, such as high-brightness aluminum. Depending on the configuration, an aluminum plate with silver vapor-deposited on it may also be used to further improve reflectivity. 【0028】 The reflector 48 of this embodiment has a reflective portion 48a that reflects radiant heat towards the fixing belt side and a pressure receiving portion 48b that receives the pressure from the pressure roller 41. The reflective portion 48a is positioned between the heat source 43 and the fixing stay 44. The pressure receiving portion 48b is positioned between a sliding member, which is a heat equalizing member 45a, and a resin pad 45b. 【0029】 Figure 3 is a perspective view showing the reflector 48, the nip forming member 45, and the fixing stay 44. As shown in Figure 3, the reflector 48 is held in place by the pressure receiving portion 48b being sandwiched between the heat equalizing member 45a and the resin pad 45b, and the part other than the pressure receiving portion 48b is not in contact with other members. 【0030】 Figure 4 is a schematic diagram of a conventional fixing device. As shown in Figure 4, conventionally, the reflector 148 did not have a pressure receiving portion 48b. The reflectivity of the reflector 148 is approximately 95-98%, meaning it cannot reflect 100% of the radiant heat from the heat source 143. The reflector itself also absorbs a small amount of radiant heat, causing its temperature to gradually rise. In particular, when a large amount of paper is fed continuously, the temperature of the reflector 148 rose to about 300°C-400°C in the conventional fixing device shown in Figure 4. When a certain level of heat load is applied to the reflector 148, the aluminum or silver layer of the reflector 148 discolors. This not only reduces the reflectivity and prevents it from performing at its full potential, but in the worst case, it can lead to safety problems. Therefore, conventionally, productivity could only be achieved up to a level that did not reach that temperature range, which was a bottleneck in improving the productivity of the machine. 【0031】 In contrast, in this embodiment, as explained with reference to Figures 2 and 3, the reflector 48 has a pressure receiving portion 48b that extends between the heat uniforming member 45a and the resin pad 45b to the region that receives pressure from the pressure roller 41. As mentioned above, the reflector 48 is made of aluminum, a metal member with good thermal conductivity, so the heat absorbed by the reflective portion 48a is quickly conducted to the entire component. Then, the heat from the reflector 48 is transferred from the pressure receiving portion 48b, which is in contact with the heat uniforming member 45a, to the heat uniforming member 45a, thereby suppressing the temperature rise of the reflector 48. Furthermore, the heat from the reflector 48 that has been transferred to the heat uniforming member 45a is transmitted to the fixing belt 42 through the heat uniforming member 45a and used for toner melting. As a result, the heat from the reflector 48 can be used more effectively compared to when the heat from the reflector 48 is dissipated to other components such as the fixing stay 44, the lighting time of the heat source 43 can be shortened, and power consumption can be reduced. 【0032】 Furthermore, the pressure receiving portion 48b is located in the pressurized region that receives the pressure from the pressure roller 41. This increases the contact between the heat uniforming member 45a and the pressure receiving portion 48b, improving heat transfer and increasing the heat dissipation efficiency of the reflector 48. Moreover, since the heat uniforming member 45a and the reflector 48 are metal members with good thermal conductivity, the heat from the reflector 48 can be efficiently dissipated to the fixing belt 42. 【0033】 Furthermore, the pressure receiving portion 48b of the reflector 48 extends from one end to the other end of the fixing belt 42, and this pressure receiving portion 48b is in direct contact with the heat equalization member 45a. The reflector itself is also made of a metal with good thermal conductivity, such as aluminum. Therefore, like the heat equalization member 45a, the pressure receiving portion 48b has a heat equalization function that removes heat from areas with high axial temperature and moves it to areas with low axial temperature to equalize the axial temperature. Thus, this pressure receiving portion 48b can assist in averaging the axial temperature of the fixing belt 42 of the heat equalization member 45a. 【0034】 Furthermore, as shown in Figures 2 and 3, a clearance is provided between the bent portion of the heat-distributing member 45a and the fixing stay 44, ensuring non-contact. This prevents heat transfer to the bent portion of the heat-distributing pad and the fixing stay, which would be unnecessary from the standpoint of efficient heat utilization. 【0035】 With the above configuration, a fixing device can be obtained that prevents the temperature of the reflector 48 from rising, effectively utilizes the heat of the reflector 48, and reduces power consumption. 【0036】 Furthermore, as described above, the heat equalization member 45a is coated with a coating that provides excellent sliding performance, so that the coefficient of friction of the surface of the pressure receiving portion 48b against the inner surface of the fixing belt 42 is lower than the coefficient of friction of the surface of the fixing belt 42 against the inner surface of the fixing belt 42. As a result, the sliding resistance of the fixing belt can be reduced compared to the case where the heat from the reflector 48 is dissipated to the fixing belt 42 by bringing the pressure receiving portion 48b of the reflector 48 into contact with the inner surface of the fixing belt 42 without going through the heat equalization member 45a. This makes it possible to suppress the increase in torque required to rotate the fixing belt 42 and also suppress wear on the inner surface of the fixing belt 42. 【0037】 Furthermore, if a coating with excellent sliding properties is applied to the pressure receiving portion 48b of the reflector 48, and the pressure receiving portion 48b is brought into contact with the inner circumferential surface of the fixing belt 42, the following problems are expected. Specifically, if the coating material with excellent sliding properties adheres to the reflective portion 48a of the reflector 48, the reflectivity may decrease. Therefore, it is necessary to prevent the coating material with excellent sliding properties from adhering to the reflective portion 48a, for example, by applying masking to the reflective portion 48a. If masking is applied to the reflective portion 48a, a process of applying masking, removing the masking, and removing the adhesive of the masking that has adhered to the reflective portion 48a will be necessary. Moreover, it is expected that performing these processes by machine will be difficult and, even if possible, will be costly. 【0038】 On the other hand, as in this embodiment, by transferring the heat from the reflector 48 to the fixing belt 42 via the heat equalization member 45a, it becomes unnecessary for the reflector 48 to have a function that provides good sliding properties with respect to the inner circumferential surface of the fixing belt 42. As a result, it becomes unnecessary to apply a coating with excellent sliding performance to the pressure receiving portion 48b, thereby suppressing increases in manufacturing difficulty and cost. 【0039】 Figure 5 is a schematic diagram showing another example of the configuration of the fixing device. The fixing device shown in Figure 5 has a concave shape when viewed from the direction of the rotation axis of the fixing stay 44, and the heat source 43 is positioned in the recessed part of the fixing stay 44. Similar to the embodiment, the reflective portion 48a of the reflector 48 is positioned between the fixing stay 44 and the heat source 43. The reflective portion 48a has a pressure receiving portion 48b that extends from the lower side in the figure and is sandwiched between the resin pad 45b and the heat equalizing member 45a. 【0040】 In the fixing device shown in Figure 5, the heat from the reflector 48 is dissipated to the fixing belt 42 via the heat equalization member 45a, and the heat from the reflector 48 can be used to melt the toner. 【0041】 Furthermore, although the heat equalization member 45a is placed between the pressure receiving portion 48b of the reflector 48 and the fixing belt 42 as described above, the member placed between the pressure receiving portion 48b and the fixing belt 42 can be any member that has better sliding properties with respect to the inner circumferential surface of the fixing belt 42 than the reflector. For example, although its heat dissipation to the fixing belt 42 is inferior to that of the heat equalization member 45a, a sliding sheet made of PTFE or other fibers impregnated with a lubricant such as silicone oil may be placed between the pressure receiving portion 48b and the fixing belt 42 as a sliding member. This sliding sheet may be placed, for example, wrapped around the resin pad 45b and fixed to the back side (fixing stay side) of the resin pad 45b with screws or the like. 【0042】 The reflective portion 48a of the reflector, which directly receives heat from the heat source, is at a higher temperature than the pressurized receiving portion 48b, which dissipates heat from the reflector 48 to the heat equalization member 45a. This temperature difference creates a difference in axial thermal expansion between the reflective portion 48a and the pressurized receiving portion 48b, which may cause abnormal deformation of the reflector 48. 【0043】 Therefore, in this embodiment, as shown in Figure 6, the pressure receiving portion 48b is provided with a plurality of notches 48c cut along the rotational direction of the fixing belt. In this way, by providing the notch 48c, the difference in axial thermal expansion between the pressure receiving portion 48b and the reflecting portion 48a can be absorbed by the axial expansion of the notch 48c in the pressure receiving portion 48b. This suppresses abnormal deformation of the reflector 48. 【0044】 Even if a notch 48c is provided in the reflective portion 48a, the axial width of the notch in the reflective portion 48a will be narrowed, which will absorb the difference in axial thermal expansion between the pressure receiving portion 48b and the reflective portion 48a, thereby suppressing abnormal deformation of the reflector 48. However, if a notch is provided in the reflective portion 48a, the radiant heat from the heat source 43 cannot be reflected at the notch, and the temperature of the fixing belt 42 at the location corresponding to the notch may decrease, potentially preventing uniform heating of the fixing belt 42 in the axial direction. Therefore, it is preferable to provide the notch 48c in the pressure receiving portion 48b, as this allows for uniform heating of the fixing belt 42 in the axial direction while suppressing abnormal deformation of the reflector 48. 【0045】 Furthermore, the pressure receiving portion 48b is provided with a notch 48c, which is shaped like a cut made with a blade, and the axial gap opened by the notch 48c is narrow. Therefore, even with the notch 48c, the pressure receiving portion 48b has sufficient area at both ends and in the axial center. Thus, even if the ends of the fixing belt 42 become hot during continuous printing of small-sized paper, and the heat from the reflector 48 cannot be dissipated from both ends of the pressure receiving portion 48b in the axial center, the heat can still be dissipated from the center of the pressure receiving portion 48b in the axial direction. As a result, even during continuous printing of small-sized paper, the temperature rise of the reflector 148 can be suppressed, and discoloration of the aluminum or silver layer of the reflector 148 can be suppressed. 【0046】 Furthermore, even if a notch 48c is provided in the pressure receiving portion 48b, heat can be transferred axially by bypassing the notch 48c, and the function of assisting in the averaging of the axial temperature of the fixing belt 42 of the heat equalization member 45a can be maintained. 【0047】 Furthermore, the thickness of the reflector 48 is 0.3 to 1.2 mm, more preferably 0.5 to 0.7 mm. If the thickness of the reflector 48 exceeds 1.2 mm, the amount of heat transferred in the axial direction at the pressure receiving portion decreases, which may reduce the function of assisting in the averaging of the axial temperature of the fixing belt 42 as described above. On the other hand, if the thickness of the reflector 48 is less than 0.3 mm, the rigidity of the reflector decreases, making it easier for abnormal deformation to occur due to the difference in thermal expansion between the reflective portion 48a and the pressure receiving portion 48b, which may prevent the abnormal deformation of the reflector 48 caused by the notch 48c from being suppressed. 【0048】 Furthermore, it is preferable to provide the notches 48c at locations corresponding to the widthwise edges of a predetermined size of paper, as shown in Figure 7. In the example shown in Figure 7, notches 48c are provided at positions corresponding to the widthwise edges of A6 portrait size paper and B4 portrait size paper. Note that this is just one example, and the paper size to which the notches 48c correspond can be appropriately determined based on the heat distribution characteristics of the two heat sources 43, etc. 【0049】 In this embodiment, as described above, the pressure receiving portion 48b and the heat equalizing member 45a remove heat from areas of the fixing belt 42 where the temperature is high, and move the removed heat to areas of the fixing belt 42 where the temperature is low, thereby equalizing the temperature of the fixing belt 42 in the axial direction. As a result, when small-sized paper is continuously fed, the heat from the non-paper-feeding area at the end of the fixing belt, where heat is not removed by the paper, can be moved to the paper-feeding area at the axial center using the pressure receiving portion 48b and the heat equalizing member 45a, thereby suppressing abnormally high temperatures in the non-paper-feeding area of ​​the fixing belt 21. 【0050】 However, the heat from the high-temperature non-paper-feeding area is transferred to the paper-feeding area by the pressure receiving section 48b and the heat equalization member 45a, causing the area near the end of the paper-feeding area of ​​the fixing belt 42 to become hotter than the fixing temperature. As a result, there is a risk of hot offset (hereinafter referred to as edge hot offset) occurring in the image at the edges of the paper. 【0051】 Figure 8(a) shows the heat transfer and temperature distribution of the fixing belt 42 when there is no notch 48c, and Figure 8(b) shows the heat transfer and temperature distribution of the fixing belt 42 when a notch 48c is provided near the widthwise edge of the paper. As shown in Figure 8(a1), if there is no notch 48c near the widthwise edge of the paper, some of the heat from the non-paper-feeding area of ​​the fixing belt 42, which has been transferred to the pressure receiving portion 48b of the reflector 48 via the heat equalization member 45a, moves to the vicinity of the end of the paper-feeding area of ​​the fixing belt 42 via the heat equalization member 45a. As a result, as shown in Figure 8(a2), the temperature near the end of the paper-feeding area of ​​the fixing belt 42 becomes high, and there is a risk of edge hot offset occurring. 【0052】 On the other hand, if a notch 48c is provided in the pressure receiving portion 48b, the heat from the fixing belt 42 that has moved to the pressure receiving portion 48b via the heat equalization member 45a will move axially, bypassing the notch, as shown in Figure 8(b1). Specifically, a portion of the heat from the non-paper-feeding area of ​​the fixing belt 42 that has moved to the pressure receiving portion 48b of the reflector 48 via the heat equalization member 45a will move towards the paper transport direction once it reaches the notch 48c. The heat that has moved to the notch 48c will move to the connection portion that connects the reflective portion 48a and the pressure receiving portion 48b of the reflector 48, go around the notch 48c, and then move back to the pressure receiving portion 48b. Then, a portion of the heat that has moved to the pressure receiving portion 48b will return to the fixing belt 42 via the heat equalization member 45a. In this way, the heat that bypasses the notch 48c provided near the widthwise edge of the paper is returned to the fixing belt 42 via the heat equalization member 45a, X mm inward from the end of the paper feeding area of ​​the fixing belt 42. Thus, a portion of the heat from the axial end of the fixing belt 42 that has moved to the pressure receiving section 48b via the heat equalization member 45a bypasses the notch 48c and moves X mm inward from the end of the paper feeding area of ​​the fixing belt 42. Therefore, the heat from the non-paper feeding area that is returned to the vicinity of the end of the paper feeding area of ​​the fixing belt 42 via the pressure receiving section 48b can be reduced, and as shown in Figure 8(b2), the temperature rise near the end of the paper feeding area of ​​the fixing belt 42 can be suppressed. In this way, by providing the notch 48c according to the widthwise size of the paper, edge hot offset can be suppressed. 【0053】 Although this may increase manufacturing costs, the pressure receiving portion 48b of the reflector 48 may be brought into direct contact with the inner circumferential surface of the fixing belt 42. 【0054】 The above is just one example; each of the following embodiments produces its own unique effects. (Aspect 1) In a fixing device comprising a fixing member such as a rotating fixing belt 42, a pressing member such as a pressing roller 41 that pressurizes a recording material passing through a nip portion formed in contact with the outer circumferential surface of the fixing member, and a heat source 43 disposed inside the fixing member, the device has a reflective member such as a reflector 48 which is disposed inside the fixing member and has a reflective portion 48a that reflects radiant heat emitted from the heat source 43 toward the inner circumferential surface of the fixing member, and a pressing receiving portion 48b that receives the pressing force of the pressing member via the fixing member, either integrally or thermally connected, the pressing receiving portion 48b extends from one end to the other end of the fixing member, and a notch 48c is provided in the pressing receiving portion 48b. In the example of a device described in Patent Document 1 in which the pressure receiving portion of each reflective member extends from one end to the other end of the fixing member (hereinafter referred to as Conventional Example 1), there is a risk that the reflective member may deform abnormally for the following reason. That is, the reflective portion that directly receives heat from the heat source is at a higher temperature than the pressure receiving portion that dissipates the heat from the reflective member to the fixing member in the contact area, resulting in a temperature difference between the reflective portion and the pressure receiving portion. This temperature difference causes a difference in axial thermal expansion between the reflective portion and the pressure receiving portion, which may lead to abnormal deformation of the reflective member. On the other hand, in the case of the device described in Patent Document 1, where the pressure receiving portion of the first reflective member is located in the axial center and the pressure receiving portions of the second reflective member are provided at both ends in the axial direction (hereinafter referred to as Conventional Example 2), it is thought that, at least for the second reflective member, the axial distance between the pressure receiving portion at one end and the pressure receiving portion at the other end is increased, thereby absorbing the difference in axial thermal expansion between the reflective portion and the pressure receiving portion and suppressing abnormal deformation of the reflective member. However, in this Conventional Example 2, the absence of a pressure receiving portion in the axial center of the second reflective member may lead to the following problems. In other words, when passing recording material that is slightly longer in the axial direction than the heating region of the first heating source, which has a heating region in the center, both the first heating source and the second heating source, which has heating regions on both sides in the axial direction, are lit to perform the fixing process. In this case, most of the heated area of ​​the fixing member heated by the second heating source becomes a non-paper-passing area. In the non-paper-passing area, no heat is absorbed by the recording material passing through the nip. Therefore, when continuously passing recording material that is slightly longer in the axial direction than the heating region of the first heating source, the ends of the fixing member become hot, and there is a risk that the temperature of the end of the fixing member will become higher than the temperature of the pressure receiving portion of the second reflective member. If the temperature of the end of the fixing member becomes higher than the temperature of the pressure receiving portion of the second reflective member, not only will the heat absorbed by the reflective portion of the second reflective member not be transferred to the fixing member via the pressure receiving portion (hereinafter referred to as heat dissipation), but conversely, heat will be transferred from the fixing member to the pressure receiving portion of the second reflective member. As a result, the second reflective member may become abnormally hot, which may cause discoloration of the second reflective member and a decrease in reflectivity. In Embodiment 1, a notch is provided in the pressure receiving portion, which extends from one end to the other end of the fixing member. Because a notch is provided in the pressure receiving portion in this way, the difference in axial thermal expansion between the reflective portion and the pressure receiving portion can be absorbed by the widening of the notch, thereby suppressing abnormal deformation of the reflective member. Furthermore, in embodiment 1, the pressure receiving portion is provided from one end to the other end of the fixing member, and the reflecting member also has a pressure receiving portion in the axial center. As a result, even if the temperature at both ends of the fixing member becomes higher than the temperature at both ends of the pressure receiving portion, and the heat absorbed by the reflecting portion can no longer be dissipated through both ends of the pressure receiving portion, this heat can be dissipated through the axial center of the pressure receiving portion. Moreover, if the temperature at both ends of the fixing member becomes higher than the temperature at both ends of the pressure receiving portion, the heat that has moved from both ends of the fixing member to both ends of the pressure receiving portion can also be dissipated through the axial center of the pressure receiving portion by bypassing the notch. Specifically, the heat that has moved from both ends of the fixing member to both ends of the pressure receiving portion moves from both ends of the pressure receiving portion to the connecting portion that connects the reflecting portion of the reflecting member and the pressure receiving portion. Then, after moving towards the axial center at this connecting portion, it moves to the axial center of the pressure receiving portion and is dissipated to the fixing member through the axial center of the pressure receiving portion. As can be seen from these, in Embodiment 1, the presence of a pressure receiving portion in the axial center, unlike the second reflective member in Conventional Example 2 which does not have a pressure receiving portion in the axial center, allows for efficient heat dissipation from the reflective member to the fixing member even when both ends of the fixing member become hot, thereby suppressing abnormally high temperatures of the reflective member. Furthermore, as described above, by dissipating the heat that has moved from both ends of the fixing member to both ends of the pressure receiving portion through the axial center of the pressure receiving portion, it is possible to equalize the temperature of the fixing member in the axial direction. 【0055】 (Aspect 2) In embodiment 1, the notch 48c is provided along the rotational direction of the fixing member, such as the fixing belt 42. According to this, the difference in axial thermal expansion between the pressure receiving portion 48b and the reflecting portion 48a can be effectively absorbed by the notch 48c. 【0056】 (Aspect 3) In embodiment 1 or 2, the notch 48c is provided at a position corresponding to the size of the recording material such as paper P. According to this, as described in the embodiment, the heat that has moved from both ends of the fixing member, such as the fixing belt 42, to both ends of the pressure receiving portion 48b can be dissipated to the fixing member on the axial side of the paper feeding area rather than the ends of the fixing member by bypassing the notch 48c. This suppresses the temperature rise at the ends of the paper feeding area of ​​the fixing member and suppresses the occurrence of end hot offset. 【0057】 (Aspect 4) In any of embodiments 1 to 3, the thickness of the reflective member such as the reflector 48 is 0.3 mm or more and 1.2 mm or less. According to this, as described in the embodiment, it is possible to suppress the decrease in the amount of heat moving in the axial direction at the pressure receiving portion 48b, and to suppress abnormal deformation due to the difference in the amount of thermal expansion between the pressure receiving portion 48b and the reflective portion 48a. 【0058】 (Aspect 5) In embodiment 4, the thickness of the reflective member such as the reflector 48 is 0.5 mm or more and 0.7 mm or less. According to this, it is possible to further suppress the decrease in the amount of heat transferred in the axial direction at the pressure receiving portion 48b, and to suppress abnormal deformation caused by the difference in the amount of thermal expansion between the pressure receiving portion 48b and the reflective portion 48a. 【0059】 (Aspect 6) An image forming apparatus comprising an image forming unit for forming an image on a recording material and a fixing device for fixing the image formed on the recording material, wherein any fixing device from embodiment 1 to 5 was used as the fixing device. According to this, it is possible to prevent the temperature rise of reflective materials such as the reflector 48, reduce power consumption by effectively utilizing unnecessary heat, and suppress abnormal deformation of the reflective materials. [Explanation of symbols] 【0060】 1: Image forming apparatus 40: Fixing device 41: Pressure roller 42: Fixing belt 43:Heat source 44: Fixing stay 45: Nip forming member 45a: Heat distribution member 45b: Resin pad 48: Reflector 48a:Reflector 48b: Pressure receiving section 48c: Notch P:Paper [Prior art documents] [Patent Documents] 【0061】 [Patent Document 1] Japanese Patent Publication No. 2017-11129

Claims

[Claim 1] A rotating fixing member, A pressing member that pressurizes the recording material passing through a nip portion formed in contact with the outer circumferential surface of the fixing member, A fixing device comprising a heat source disposed inside the fixing member, The reflective member comprises a reflective portion that reflects radiant heat emitted from the heat source toward the inner circumferential surface of the fixing member, and a pressure receiving portion that receives the pressure of the pressure member via the fixing member, either integrally or thermally connected. The fixing device is characterized in that the pressure receiving portion is formed by a single member that extends continuously from one end to the other end of the fixing member, and a notch is provided in the pressure receiving portion. [Claim 2] In the fixing device according to claim 1, The fixing device is characterized in that the notch is provided along the rotational direction of the fixing member. [Claim 3] In the fixing device according to claim 1, A fixing device characterized in that the aforementioned cuts are provided at positions corresponding to the widthwise edges of the recording material of a predetermined size. [Claim 4] In the fixing device according to claim 1, A fixing device characterized in that the thickness of the reflective member is 0.3 mm or more and 1.2 mm or less. [Claim 5] In the fixing device according to claim 4, A fixing device characterized in that the thickness of the reflective member is 0.5 mm or more and 0.7 mm or less. [Claim 6] An image forming unit that forms an image on the recording material, An image forming apparatus comprising a fixing device for fixing an image formed on the recording material to the recording material, An image forming apparatus characterized in that the fixing device is the fixing device described in claim 1.

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