Fixing device and image forming apparatus equipped therewith

Abstract

This further suppresses the temperature rise of the retaining member that holds the end of the fixing sleeve. [Solution] The fixing sleeve comprises a fixing sleeve, a retaining flange that holds the axial end of the fixing sleeve and has a lubricant applied between it and the fixing sleeve, a heating member disposed inside the fixing sleeve, a pressurizing member disposed opposite the outer circumferential surface of the fixing sleeve and applying pressure to a recording medium passing between it and the outer circumferential surface of the fixing sleeve, a heat shielding member disposed between the fixing sleeve and the heating member near both axial ends of the fixing sleeve, a reflecting member that reflects heat radiated from the heating member toward the inner circumferential surface of the fixing sleeve, and a sliding member that is in contact with the reflecting member and slidably in contact with the inner circumferential surface of the fixing sleeve, wherein the outermost end of the heat shielding member on the axial end side of the fixing sleeve is located closer to the axial center of the fixing sleeve than the outermost end of the retaining flange on the axial center side.

Description

Technical Field

[0001] The present invention relates to a fixing device and an image forming apparatus including the same.

Background Art

[0002] In an image forming apparatus such as a copying machine or a printer, it is known to mount a fixing device that fixes an unfixed image on a recording medium by heating the recording medium such as paper. In such a fixing device, a configuration in which a heat insulating member is arranged to suppress the temperature rise at the end of a fixing sleeve for fixing an unfixed image on the recording medium to the recording medium is disclosed in, for example, Patent Document 1.

[0003] In what is disclosed in Patent Document 1, in a fixing device including a rotatably held fixing belt, a heater for heating the fixing belt, and a belt holding member for holding a longitudinal end of the fixing belt, a shielding portion for shielding heat transfer from the heater is provided. The shielding portion has a first heat insulating plate facing the heater and the fixing belt, and a second heat insulating plate facing the belt holding member, and a space for suppressing heat transfer between the two is provided between the first heat insulating plate and the second heat insulating plate. By adopting such a configuration, the temperature rise of the belt holding member is suppressed.

Summary of the Invention

Problems to be Solved by the Invention

[0004] In the fixing device provided with a holding member for holding the longitudinal end of the fixing sleeve as described above, a lubricant such as oil for improving the slidability inside the fixing sleeve adheres to the holding member, and when the temperature becomes high, the lubricant evaporates and fine particles are generated. In particular, since the heat insulating plate always receives heat from the heater and thus tends to become very high temperature, and is also arranged close to the holding member holding the fixing sleeve, fine particles are likely to be generated.

[0005] Therefore, in a fixing device that heats the fixing sleeve with a heating element, it is preferable to further suppress the temperature rise of the holding element that holds the end of the fixing sleeve. [Means for solving the problem]

[0006] The fixing device of the present invention is A rotatably held fixing sleeve, A retaining flange is provided, which holds the axial end of the fixing sleeve and has a lubricant applied between it and the fixing sleeve. A heating element is positioned inside the aforementioned fixing sleeve and radiates heat, A pressurizing member is positioned opposite the outer circumferential surface of the fixing sleeve and applies pressure to the recording medium passing between the outer circumferential surface of the fixing sleeve and the pressing member, A heat shielding member is disposed between the fixing sleeve and the heating member near both ends in the axial direction of the fixing sleeve, A reflective member that reflects the heat radiated from the heating element toward the inner surface of the fixing sleeve, It has a sliding member that is in contact with the reflective member and is slidably in contact with the inner circumferential surface of the fixing sleeve, The heat shielding member is such that the outermost end on the axial end side of the fixing sleeve is located closer to the axial center of the fixing sleeve than the outermost end on the axial center side of the retaining flange. [Effects of the Invention]

[0007] According to the present invention, in a fixing device that heats a fixing sleeve with a heating element, the temperature rise of the holding element that holds the end of the fixing sleeve can be further suppressed. [Brief explanation of the drawing]

[0008] [Figure 1] This is a schematic diagram of one embodiment of the image forming apparatus of the present invention. [Figure 2] Figure 1 is a schematic diagram showing one embodiment of the fixing device. [Figure 3]Figure 2 is a perspective view showing the reflector, nip forming member, and fixing stay. [Figure 4] This figure illustrates the arrangement of the heat shielding members in the fixing device shown in Figure 2. [Figure 5] This is a diagram illustrating the effects of this embodiment. [Figure 6] This is a diagram illustrating the effects of this embodiment. [Figure 7] This graph shows the number of lubricant particles generated in relation to temperature. [Figure 8] This figure shows another embodiment of the fixing device of the present invention. [Figure 9] This figure shows another embodiment of the fixing device of the present invention. [Figure 10] This figure shows another embodiment of the fixing device of the present invention. [Figure 11] This figure shows another embodiment of the fixing device of the present invention. [Modes for carrying out the invention]

[0009] Embodiments of the present invention will be described below with reference to the drawings.

[0010] <Image forming apparatus> Figure 1 is a schematic diagram of one embodiment of the image forming apparatus of the present invention.

[0011] The image forming apparatus in this embodiment is an electrophotographic image forming apparatus 1 as shown in Figure 1.

[0012] The image forming apparatus 1 includes an image forming unit 100 that forms an image on a recording medium, paper P. The image forming unit 100 has image forming units 10Y, 10M, 10C, and 10K for each color, yellow (Y), magenta (M), cyan (C), and black (K), arranged along the rotational direction of an intermediate transfer belt 20 which serves as an intermediate transfer body. The image forming apparatus 1 is a tandem type image forming apparatus equipped with an image forming unit 100 having this configuration. Each image forming unit 10Y, 10M, 10C, and 10K is equipped with a photoreceptor 11Y, 11M, 11C, and 11K, respectively, which serve as a latent image carrier. Furthermore, each image forming unit 10Y, 10M, 10C, and 10K is equipped with a charging device 71 as a charging means, an optical writing device 9 as an electrostatic latent image forming means, and a developing device 72 as a developing means, respectively, around the photoreceptor 11Y, 11M, 11C, and 11K. Furthermore, the photoreceptors 11Y, 11M, 11C, and 11K are surrounded by a primary transfer roller 74 as a primary transfer means and a cleaning device 73 as a cleaning means.

[0013] The charging device 71 uniformly charges the surfaces of the photoreceptors 11Y, 11M, 11C, and 11K to a predetermined potential. The optical writing device 9 exposes the surfaces of the photoreceptors 11Y, 11M, 11C, and 11K, which have been uniformly charged by the charging device 71, according to the image information, and writes an electrostatic latent image. The developing device 72 creates a toner image by developing the electrostatic latent image on the photoreceptors 11Y, 11M, 11C, and 11K and depositing toner of each respective color (Y, M, C, K). The primary transfer roller 74 transfers the toner image on the photoreceptors 11Y, 11M, 11C, and 11K onto the intermediate transfer belt 20. The cleaning device 73 cleans the photoreceptors 11Y, 11M, 11C, and 11K by removing any remaining toner.

[0014] 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. A pickup roller 61 is located on the paper feed cassette 60. A secondary transfer roller 30 is located in the area facing the intermediate transfer belt 20, and a pair of registration rollers 62 is located between the pickup roller 61 and the secondary transfer roller 30.

[0015] On the upper part of the image forming apparatus 1, there are provided a paper discharge roller 63 for discharging the paper P and a paper discharge tray 50 on which the discharged paper P is placed. Further, between the secondary transfer roller 30 and the paper discharge roller 63, a fixing device 40 as a fixing means is provided. The fixing device 40 fixes the color toner image onto the paper P by the action of heat and pressure.

[0016] In the image forming apparatus 1, with the surfaces of the photoreceptors 11Y, 11M, 11C, and 11K uniformly charged to a predetermined potential by the charging device 71, an electrostatic latent image corresponding to the image information is written onto the surfaces of the photoreceptors 11Y, 11M, 11C, and 11K by the light writing device 9. Then, by a developing process in which the developing device 72 attaches toner of each color (Y, M, C, K) to the electrostatic latent images on the photoreceptors 11Y, 11M, 11C, and 11K, toner images are created.

[0017] The toner images of each color formed on each of the photoreceptors 11Y, 11M, 11C, and 11K are primarily transferred onto the intermediate transfer belt 20 so as to overlap each other by the primary transfer roller 74, and a color toner image is formed on the intermediate transfer belt 20. The color toner image formed on the intermediate transfer belt 20 is conveyed to a region (secondary transfer region) where the intermediate transfer belt 20 and the secondary transfer roller 30 face each other as the intermediate transfer belt 20 rotates.

[0018] On the other hand, the paper P held in the paper feed cassette 60 is fed one by one by the pickup roller 61. The paper P fed from the paper feed cassette 60 is conveyed to the secondary transfer region at a predetermined timing by the registration roller pair 62 along the conveyance path.

[0019] Then, the color toner image formed on the intermediate transfer belt 20 is secondarily transferred onto the paper P conveyed to the secondary transfer region by the secondary transfer roller 30. The paper P on which the image is formed by the transfer of the color toner image is then conveyed to the fixing device 40.

[0020] In the fixing device 40, heat and pressure are applied to the paper P onto which the color toner image has been transferred, thereby fixing the color toner image onto the paper P.

[0021] The paper P, on which the color toner image has been fixed, is transported along the transport path and discharged into the output tray 50 by the output roller 63.

[0022] <Fusing device> Figure 2 is a schematic diagram showing one embodiment of the fixing device 40 shown in Figure 1.

[0023] As shown in Figure 2, the fixing device 40 in this embodiment includes a pressure roller 41, a fixing belt 42, and a heater 43, and fixes the color toner image by applying pressure while applying heat to the paper P.

[0024] The pressure roller 41 is an example of a pressure member in the present invention and is positioned opposite the outer circumferential surface of the fixing belt 42. The pressure roller 41 has a silicone rubber layer on the outer circumference 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. The pressure roller 41 is pressed against the fixing belt 42 by a spring or the like, and the rubber layer is compressed and deformed, creating a predetermined nip width between it and the fixing belt 42. The pressure roller 41 rotates when a driving force is transmitted from a drive source such as a motor provided in the image forming apparatus 1 via gears. The pressure roller 41 may be a solid roller, but a hollow roller is preferable because it has a lower heat capacity. The pressure roller 41 may also have a heating source such as a halogen heater. The silicone rubber layer may be solid rubber, but if there is no heater inside the pressure roller 41, sponge rubber may be used. Using sponge rubber is more desirable because it has higher heat insulation properties and prevents heat from being lost from the fixing belt.

[0025] The fixing belt 42 is an example of a fixing sleeve in the present invention. The fixing belt 42 is positioned opposite the pressure roller 41, and rotates together with it as the driving force of the pressure roller 41 is transmitted via the nip portion N. As a result, pressure is applied to the paper P passing between the pressure roller 41 and the outer surface of the fixing belt 42.

[0026] The fixing belt 42 is an endless belt (or film) made of a metal belt such as nickel or SUS, or a resin material such as polyimide. The surface layer of the fixing belt 42 has a release layer such as a PFA or PTFE layer to prevent toner from adhering to it.

[0027] An elastic layer, such as a layer of silicone rubber, may be present between the substrate and the release layer of the fixing belt 42. If the silicone rubber layer is absent, the heat capacity will be reduced and fixing performance will improve, but when the unfixed image is fixed by pressurizing, subtle irregularities on the belt surface will be transferred to the image, resulting in the problem of orange peel-like marks remaining in the solid areas of the image. To improve this, it is necessary to provide a silicone rubber layer of 100 μm or more. The deformation of the silicone rubber layer will absorb the subtle irregularities, improving the orange peel-like image.

[0028] A nip-forming member 45, held by a fixing stay 44 which is a stay member, is positioned within the fixing belt 42.

[0029] The nip-forming member 45 consists of a heat-distributing member 45a positioned in the nip portion N 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 an increase in warm-up time and TEC (Typical Electricity Consumption) value.

[0030] The heat equalization member 45a is an example of a sliding member in the present invention. The heat equalization member 45a also functions as a heat transfer member. The heat equalization member 45a is, for example, a pad shape that extends in the width direction of the fixing belt 42. This heat equalization member 45a is positioned to equalize the axial temperature of the fixing belt 42 by slidably contacting the inner circumferential surface of the fixing belt 42. That is, the heat equalization member 45a 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. In the example shown in Figure 2, the shape of the nip portion N is flat, but it may be concave or have other shapes. By forming a concave nip, the discharge direction of the leading edge of the paper is closer to the pressure roller 41, improving the separation of the paper from the fixing belt 42 and suppressing the occurrence of jams.

[0031] The heat-distributing member 45a is a metal member such as aluminum or copper with high thermal conductivity of 50 [W / m·K] or more, and the surface of the heat-distributing member 45a is coated with a coating that has excellent sliding properties. Examples of coating materials include resin-based materials such as polyimide resin, fluororesin, polyphenylene sulfide resin, or saturated polyester resin. Alternatively, glass fiber, carbon, graphite, fluorinated graphite, carbon fiber, molybdenum disulfide, fluororesin, etc., may be mixed with such a resin-based coating material.

[0032] Furthermore, metal-based materials can also be used as coating materials. Examples of metal-based coating materials include molybdenum disulfide, nickel, and composite plating of nickel and fluororesin. Other examples of metal-based coating materials include anodized aluminum or anodized aluminum impregnated with resin or metal. Ceramics can also be used as coating materials. Examples of ceramics used as coating materials include silicon carbide ceramics, silicon carbide ceramics, alumina ceramics, and mixtures of these with molybdenum disulfide, fluororesin, etc.

[0033] Furthermore, a method is also effective in which an anodized layer is formed on the surface of a heat-distributing member 45a made of aluminum or an aluminum alloy, and molybdenum disulfide, produced by secondary electrolysis, is filled into the micropores of the anodized layer from the deepest part of the micropores to the outermost layer.

[0034] 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. It prevents the nip forming member 45, which is subjected to pressure by the pressure roller 41, from bending, and ensures that a uniform nip width is obtained in the axial direction.

[0035] Furthermore, a heat shield member 46 is positioned within the fixing belt 42. The heat shield member 46 is made of a metal material with excellent heat resistance and high thermal conductivity, such as SUS, aluminum, or copper. The heat shield member 46 is positioned between the heater 43 and the fixing belt 42 near both axial ends of the fixing belt 42. As a result, the heat shield member 46 suppresses heat transfer from the heater 43 to the fixing belt 42, thereby suppressing the temperature rise in the region near both axial ends of the fixing belt 42.

[0036] The heater 43 is an example of a heating element in the present invention, and for example, a halogen heater may be used.

[0037] Two heaters 43 are provided inside the fixing belt 42. The two heaters 43 have a shape that extends parallel to each other in the axial direction of the fixing belt 42. The fixing belt 42 is directly heated from the inner circumference by radiant heat emitted from the heaters 43. Here, the heating element 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.

[0038] Furthermore, a reflector 48 is positioned within the fixing belt 42 to minimize the loss of radiant heat from the heater 43. The reflector 48 is an example of a reflective member in the present invention. By being positioned within the fixing belt 42, the reflector 48 reflects the radiant heat from the heater 43 toward the inner surface of the fixing belt 42. The reflector 48 is made of high-brightness aluminum, which is based on high-purity aluminum as a metal material and has multiple reflective or protective films formed on its surface. Depending on the configuration, a material with silver vapor-deposited onto an aluminum plate to further improve reflectivity may also be used.

[0039] The reflector 48 of this embodiment has a reflective portion 48a and a pressure receiving portion 48b. The reflective portion 48a is positioned between the heater 43 and the fixing stay 44 and reflects the radiant heat from the heater 43 toward the inner circumferential surface of the fixing belt 42. The pressure receiving portion 48b is positioned between the heat equalization member 45a and the resin pad 45b and receives the pressure applied by the pressure roller 41.

[0040] Figure 3 is a perspective view showing the reflector 48, nip forming member 45, and fixing stay 44 shown in Figure 2.

[0041] 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.

[0042] The reflector 48 has a pressure receiving portion 48b that extends between the heat equalization member 45a and the resin pad 45b, into the region that receives pressure from the pressure roller 41. Since the reflector 48 is made of aluminum, a metal material with good thermal conductivity, the heat absorbed by the reflective portion 48a is quickly conducted to the entire reflector 48. As a result, heat from the reflector 48 is transferred from the pressure receiving portion 48b, which is in contact with the heat equalization member 45a, to the heat equalization 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 equalization member 45a is transmitted to the fixing belt 42 through the heat equalization member 45a and used for toner melting. This allows for more effective utilization of the heat from the reflector 48 compared to dissipating heat to other components such as the fixing stay 44, shortening the power supply time of the heater 43 and reducing power consumption.

[0043] 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.

[0044] Furthermore, as shown in Figures 2 and 3, the reflector 48 is kept in non-contact with the bent portion of the heat-distributing member 45a and the fixing stay 44 by providing a clearance. This prevents heat transfer to the bent portion of the heat-distributing member 45a and the fixing stay 44, which would be unnecessary from the standpoint of efficient heat utilization.

[0045] With the above configuration, the temperature of the reflector 48 can be prevented from rising, the heat from the reflector 48 can be effectively utilized, and power consumption can be reduced.

[0046] 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. This reduces the sliding resistance of the fixing belt 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 suppresses the increase in torque required to rotate the fixing belt 42 and also suppresses wear on the inner surface of the fixing belt 42.

[0047] 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, processes such as 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.

[0048] 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 against the inner 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.

[0049] Furthermore, in this embodiment, a heat-distributing member 45a is placed between the pressure receiving portion 48b of the reflector 48 and the fixing belt 42. However, the member placed between the pressure receiving portion 48b and the fixing belt 42 only needs to have better sliding properties with respect to the inner circumferential surface of the fixing belt 42 than the reflector 48. For example, although its heat dissipation to the fixing belt 42 is inferior to that of the heat-distributing 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 the pressure receiving portion 48b and fixed with screws or the like on the back side of the resin pad 45b (on the fixing stay 44 side).

[0050] Here, we will explain the position of the heat shielding member 46 in the axial direction of the fixing belt 42.

[0051] Figure 4 is a diagram illustrating the arrangement of the heat shield member 46 in the fixing device 40 shown in Figure 2, and is an arrangement view taken from a direction perpendicular to the axial direction of the fixing belt 42. In Figure 4, for the sake of clarity, only one heater 43 is shown, and the fixing stay 44, nip forming member 45, and reflector 48 are omitted from the illustration.

[0052] As shown in Figure 4, in the fixing device 40 of this embodiment, both axial ends of the fixing belt 42 are held by flanges 47.

[0053] The flange 47 is an example of a retaining flange in the present invention and has an annular portion 47a and a cylindrical portion 47b. The annular portion 47a is a member formed in an annular shape with a hole. The cylindrical portion 47b is configured in a cylindrical shape, with one end continuous with the inner circumference of the annular portion 47a.

[0054] The flange 47, configured in this way, holds the axial end of the anchoring belt 42 by having its cylindrical portion 47b fitted inside the axial end of the anchoring belt 42. At this time, the annular portion 47a covers the axial end face of the anchoring belt 42.

[0055] Furthermore, as described above, the heat shield member 46 is positioned between the fixing belt 42 and the heater 43 near both axial ends of the fixing belt 42. In this case, the heat shield member 46 is positioned outside the paper-passing area W1 through which the paper P passes on the outer surface of the fixing belt 42. In this embodiment, the outermost end 46a of the heat shield member 46 on the axial end side of the fixing belt 42 is located further towards the axial center (arrow A side) of the fixing belt 42 than the outermost end 47c of the flange 47 on the axial center side.

[0056] Figures 5 and 6 are diagrams illustrating the effects of this embodiment. Figure 7 is a graph showing the number of fine particles generated by the lubricant in relation to temperature.

[0057] The heat shielding members 46 are positioned at both ends of the fixing belt 42 in the axial direction, and suppress the temperature rise at the ends of the fixing belt 42 during continuous paper feeding in the area where the heater 43 extends beyond the paper feeding area W1 (see Figure 4). For this reason, the axial length of the heat shielding members 46 of the fixing belt 42 is designed to be long enough to suppress the temperature rise at the ends of the fixing belt 42, and the positional relationship between the fixing belt 42 and the flange 47 in the axial direction is determined at that time.

[0058] As shown in Figure 5, when the heat shield member 546 is positioned so as to partially overlap the flange 47 in the axial direction of the fixing belt 42, radiant heat from the heater 43 is more easily transferred to the flange 47 via the heat shield member 546. Here, the flange 47 has a lubricant such as oil attached to it to improve the sliding properties within the fixing belt 42, and when it gets hot, the lubricant evaporates and fine particles are generated.

[0059] On the other hand, in this embodiment, the reflector 48, a metal member that easily conducts heat from the heater 43, is positioned in contact with the heat-uniforming member 45a, a metal member that equalizes the axial temperature of the fixing belt 42. Therefore, the axial temperature distribution of the fixing belt 42, which slides in contact with the heat-uniforming member 45a, can be made even more uniform than in the conventional design (dashed line in Figure 5) (solid line in Figure 5). In this case, if the thermal conductivity of the reflector 48 is higher than that of the heat-shielding member 46, the axial temperature distribution of the fixing belt 42 can be made even more uniform.

[0060] As a result, as shown in Figures 4 and 5, the heat shield member 46 can be positioned such that the outermost end 46a on the axial end side of the fixing belt 42 is located closer to the axial center of the fixing belt 42 than the outermost end 47c on the axial center side of the flange 47. In other words, the distance between the heat shield member 46 and the flange 47 can be made longer than in the conventional configuration.

[0061] Here, as shown in Figure 6, the temperature of the flange 47 when the distance between the heat shield member 46 and the flange 47 is long (white circle in Figure 6) is lower than the temperature of the flange 47 when the distance between the heat shield member 46 and the flange 47 is short (triangle in Figure 6). This is because the amount of insulation provided by the air between the heat shield member 46 and the flange 47 increases, making it more difficult for radiant heat from the heater 43 to be transferred to the flange 47 via the heat shield member 46.

[0062] Furthermore, as the radiant heat from the heater 43 is less likely to be transmitted to the flange 47 via the heat shielding member 46, the generation of fine particles from fluorine grilles, silicone oil, etc. can be reduced, as shown in Figure 7.

[0063] (Other embodiments) Figure 8 shows another embodiment of the fixing device of the present invention, and is a layout view taken from a direction perpendicular to the axial direction of the fixing belt 42. In Figure 8, for the sake of clarity, the heater 43 shown in Figure 2 is shown as one, and the fixing stay 44, nip forming member 45, and reflector 48 are omitted from the illustration.

[0064] As shown in Figure 8, the shape of the heat shield member 46 in this embodiment differs from that shown in Figure 4. In this embodiment, the heat shield member 46 has the shape of a right triangle when viewed from a direction perpendicular to the axial direction of the fixing belt 42. The distance W3 between the inclined surface 46b of the right triangle and the extension line EL extending axially from the central end 47c of the flange 47 widens towards the axial end 42a of the fixing belt 42. In other words, in this embodiment, the heat shield member 46 is shaped to move away from the flange 47 as it approaches the axial end 42a of the fixing belt 42.

[0065] By increasing the distance between the heat shield member 46 and the flange 47 in this way, the temperature rise of the flange 47 can be suppressed, as shown in Figure 6, based on the relationship between the distance between the heat shield member 46 and the flange 47 and the temperature rise of the flange 47. As a result, the amount of fine particle generation can be suppressed, as shown in Figure 7.

[0066] In this embodiment, the distance W3 between the right-angled triangular slope 46b of the heat shield member 46 and the extension line EL extending axially from the central end 47c of the flange 47 widens towards the axial end 42a of the anchoring belt 42. However, by tilting the plate-shaped heat shield member 46, the distance W3 between the extension line EL extending axially from the central end 47c of the flange 47 and the heat shield member 46 may be configured to widen towards the axial end 42a of the anchoring belt 42.

[0067] Figure 9 shows another embodiment of the fixing device of the present invention, and is a layout view of the fixing belt 42 as seen from the axial direction. Note that in Figure 9, the pressure roller 41 and flange 47 are omitted from the illustration for clarity of the explanation.

[0068] As shown in Figure 9, this embodiment differs from the one shown in Figure 2 in that the heat shielding member 46 is in contact with the reflector 48 at the connection portion 48c and is thermally connected to it. In addition, the heater 43 includes a central heater 43a positioned in the central part of the fixing belt 42 and an end heater 43b positioned at the end of the fixing belt 42.

[0069] This configuration allows heat accumulated in the heat shielding member 46 to be released through the reflector 48, further suppressing the temperature rise of the heat shielding member 46. This suppresses the generation of fine particles. In this case, since the reflector 48 is in contact with the heat equalizing member 45a which is in contact with the fixing belt 42, when the temperature of the heat shielding member 46 rises, heat flows to the heat equalizing member 45a which is at a lower temperature, thus suppressing the temperature rise of the heat shielding member 46. In addition, by making the thermal conductivity of the reflector 48 higher than that of the heat shielding member 46, heat flows more easily to the reflector 48, suppressing the temperature rise of the heat shielding member 46 and suppressing the generation of fine particles.

[0070] Figure 10 shows another embodiment of the fixing device of the present invention, and is a layout view of the fixing belt 42 as seen from the axial direction. Note that in Figure 9, the flange 47 is omitted from the illustration for clarity of the explanation.

[0071] As shown in Figure 10, this embodiment differs from the one shown in Figure 2 in that the heat shielding member 46 is in slidable contact with the inner circumferential surface of the fixing belt 42.

[0072] With this configuration, if the temperature of the heat shielding member 46 rises and becomes higher than the temperature of the fixing belt 42, the heat accumulated in the heat shielding member 46 can be released to the fixing belt 42 because the heat shielding member 46 is in contact with the fixing belt 42. As a result, the temperature rise of the heat shielding member 46 can be further suppressed, and the amount of fine particle generation can be suppressed.

[0073] Figure 11 shows another embodiment of the fixing device of the present invention, and is a layout view taken from a direction perpendicular to the axial direction of the fixing belt 42. In Figure 11, for the sake of clarity of explanation, the heater 43 shown in Figure 2 is shown as one, and the fixing stay 44, nip forming member 45, and reflector 48 are omitted from the illustration.

[0074] As shown in Figure 11, this embodiment differs from the one shown in Figure 4 in that it includes a heat insulating member 49. The heat insulating member 49 may be a general-purpose material that has the effect of blocking heat, and is placed between the heat shielding member 46 and the heater 43.

[0075] In this case, the increase in the amount of fine particles generated is due to the heat shielding member 46 receiving radiant heat from the heater 43, which causes its temperature to rise, and the heat from the heat shielding member 46 being transferred to the flange 47 via the air, causing the temperature of the flange 47 to rise.

[0076] In this embodiment, the placement of the heat-insulating member 49 between the heat-shielding member 46 and the heater 43 suppresses the transfer of radiant heat from the heater 43 to the heat-shielding member 46, thereby suppressing the temperature rise of the heat-shielding member 46. As a result, the amount of fine particles generated can also be suppressed in this embodiment.

[0077] It should be noted that the present invention is not limited to the configurations shown in the above embodiments, including combinations with other elements. These aspects can be modified without departing from the spirit of the present invention and can be appropriately determined according to their application.

[0078] Examples of the present invention are as follows:

[0079] (Note 1) A rotatably held fixing sleeve, A retaining flange is provided, which holds the axial end of the fixing sleeve and has a lubricant applied between it and the fixing sleeve. A heating element is positioned inside the aforementioned fixing sleeve and radiates heat, A pressurizing member is positioned opposite the outer circumferential surface of the fixing sleeve and applies pressure to the recording medium passing between the outer circumferential surface of the fixing sleeve and the pressing member, A heat shielding member is disposed between the fixing sleeve and the heating member near both ends in the axial direction of the fixing sleeve, A reflective member that reflects the heat radiated from the heating element toward the inner surface of the fixing sleeve, It has a sliding member that is in contact with the reflective member and is slidably in contact with the inner circumferential surface of the fixing sleeve, The heat shielding member is a fixing device in which the outermost end of the fixing sleeve on the axial end side is located closer to the axial center of the fixing sleeve than the outermost end of the retaining flange on the axial center side.

[0080] (Note 2) The fixing device according to Appendix 1, wherein the thermal conductivity of the reflective member is higher than that of the heat-shielding member.

[0081] (Note 3) The heat-shielding member is in contact with the reflective member, as described in Appendix 1, in the fixing device.

[0082] (Note 4) The fixing device according to Appendix 1, wherein the heat shielding member has a shape in which the distance between the axial central end of the retaining flange and the extension line extending in the axial direction widens towards the axial end of the fixing sleeve.

[0083] (Note 5) The fixing device according to Appendix 1, wherein the heat shielding member is slidably in contact with the inner circumferential surface of the fixing sleeve.

[0084] (Note 6) The fixing device according to Appendix 1, wherein a heat insulating member is arranged between the heat shielding member and the heating member.

[0085] (Note 7) An image forming apparatus equipped with a fixing device as described in any one of the appendices 1 to 6. [Explanation of symbols]

[0086] 1. Image forming apparatus 9. Optical writing device 10Y,10M,10C,10K Imaging section 11Y,11M,11C,11K photoreceptor 20 Intermediate transfer belt 30 Secondary transfer roller 40 Fixing device 41 Pressure roller 42 Fixing belt 43 Heater 43a Central heater 43b End heater 44 Fixing stay 45 Nip forming member 45a Heating element 45b Resin pad 46 Heat-shielding material 46a,47c end 47 Flange 47a Ring section 47b Cylindrical part 48c Connection 48 Reflectors 48a Reflector 48b Pressure receiving section 49. Insulation material 50 Paper Output Tray 60 Paper feed cassettes 61 Pickup Roller 62 Resistola vs 63 Paper output roller 71 Charging device 72 Developing equipment 73 Cleaning device 100 Image forming unit N Nip section P paper [Prior art documents] [Patent Documents]

[0087] [Patent Document 1] Japanese Patent Publication No. 2024-20152

Claims

1. A rotatably held fixing sleeve, A retaining flange is provided, which holds the axial end of the fixing sleeve and has a lubricant applied between it and the fixing sleeve. A heating element is positioned inside the aforementioned fixing sleeve and radiates heat, A pressurizing member is positioned opposite the outer circumferential surface of the fixing sleeve and applies pressure to the recording medium passing between the outer circumferential surface of the fixing sleeve and the pressing member, A heat shielding member is disposed between the fixing sleeve and the heating member near both ends in the axial direction of the fixing sleeve, A reflective member that reflects the heat radiated from the heating element toward the inner surface of the fixing sleeve, It has a sliding member that is in contact with the reflective member and is slidably in contact with the inner circumferential surface of the fixing sleeve, The heat shielding member is a fixing device in which the outermost end of the fixing sleeve on the axial end side is located closer to the axial center of the fixing sleeve than the outermost end of the retaining flange on the axial center side.

2. The fixing device according to claim 1, wherein the thermal conductivity of the reflective member is higher than that of the heat-shielding member.

3. The fixing device according to claim 1, wherein the heat shielding member is in contact with the reflective member.

4. The fixing device according to claim 1, wherein the heat shielding member has a shape in which the distance between it and an extension line extending in the axial direction from the axial central end of the retaining flange widens towards the axial end of the fixing sleeve.

5. The fixing device according to claim 1, wherein the heat shielding member is slidably in contact with the inner circumferential surface of the fixing sleeve.

6. The fixing device according to claim 1, wherein a heat insulating member is disposed between the heat shielding member and the heating member.

7. An image forming apparatus comprising a fixing device according to any one of claims 1 to 6.

Images