Fixing device and image forming apparatus

Abstract

To provide a fixing device that increases the effect of reducing power consumption without increasing the size of the device.SOLUTION: A fixing device fixes a toner image on a recording medium to the recording medium, and comprises: two rotating bodies 21, 22 that are in contact with each other to form a nip part; heating means 23 that heats at least one of the two rotating bodies; heat insulating members 203, 220 that are arranged opposite to at least one of the two rotating bodies; and a sheet member 230 that is provided in contact with the heat insulating members. The sheet member includes silica aerogel, and has a thickness of less than 1 mm.SELECTED DRAWING: Figure 2

Description

Technical Field

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

Background Art

[0002] Conventionally, a fixing device is known that passes a recording material through a nip portion formed by two rotating bodies and fixes a toner image on the recording material. The two rotating bodies include a fixing member and a pressing member that abuts against the outer peripheral surface of the fixing member and presses the recording material.

[0003] In such a fixing device, the temperature during fixing is not increased by heating means, and attempts have been made to reduce power consumption.

[0004] Patent Document 1 discloses providing a heat retaining cover facing at least one of the two rotating bodies forming the nip portion. Further, Patent Document 1 discloses a contact and separation mechanism that moves the opposing rotating body that the heat retaining cover faces among the two rotating bodies to bring the opposing rotating body into contact with and away from the other rotating body. When the contact and separation mechanism moves, the heat retaining cover is moved while maintaining the opposing interval between the heat retaining cover and the opposing rotating body. According to Patent Document 1, it is possible to prevent a decrease in the heat retaining effect and contact with the opposing rotating body regardless of the displacement of the opposing rotating body that the heat retaining cover faces among the two rotating bodies forming the nip portion.

[0005] Patent Document 2 discloses a fixing device having shielding means for preventing heat from flowing out from inside the fixing device to the outside. The shielding means is disclosed to be composed of a rigid member and a member having a region containing air. According to Patent Document 2, it is possible to effectively retain the heat obtained inside the fixing device without allowing it to flow out to the outside, and it is said to have excellent heat retention.

[0006] Patent Document 3 discloses a fixing device having a frame that supports a heating member and a cover that covers the frame. In Patent Document 3, a recording material is sandwiched and conveyed by a heating member and a pressure member, and an unfixed image formed on the recording material is heat-fixed on the recording material by heat from the heating member. Further, Patent Document 3 discloses providing a sheet-like heat insulating member composed of fibers. According to Patent Document 3, it is said that while achieving miniaturization and weight reduction, heat retention and user protection with an excellent heat insulating effect can be realized with a simple configuration.

[0007] Patent Document 4 discloses a fixing device including a rotating member having a built-in heat source, a housing that houses the rotating member, and a partitioning member disposed along the rotation axis direction of the rotating member and partitioning between the rotating member and the inner surface of the housing. The partitioning member has a roof portion located above the rotating member and a fixing portion that is in contact with and fixed to the housing. Further, the fixing portion is provided below the upper end of the rotating member. Also, Patent Document 4 discloses that a heat insulating member is provided between the rotating member and the roof portion along the rotation axis direction of the rotating member. According to Patent Document 4, by eliminating the fixing portion that fixes the partition plate to the housing from above the heat roller, heat conduction to the housing above the heat roller can be suppressed. Also, according to Patent Document 4, it is said that heat outflow to the outside of the fixing device can be inhibited and the power consumption required for heating the heat roller can be reduced.

Summary of the Invention

Problems to be Solved by the Invention

[0008] However, further improvements as follows are required in the prior art. In Patent Document 1, further improvement in energy efficiency is desired. The heat insulation cover in Patent Document 1 is, for example, a member made of metal or resin. In the case of a resin member, it is easy to absorb heat from the fixing member and the pressing member, and it is difficult to use the absorbed heat for fixing. Therefore, even when the heat insulation cover is made of a resin member or the like, it is desired to enhance energy efficiency. Further, when the surface of the heat insulation cover is finished or a reflective surface is formed by vapor deposition, the heat insulation effect may decrease due to dirt caused by toner or lubricant over time, and it is desired to enhance energy efficiency over time.

[0009] In Patent Document 2, it is heat insulation using air, and the exterior cover of the fixing device has a structure in which an air heat insulation layer is sandwiched. However, the thinner the resin is closer to the heat source, the easier it is to deform due to heat, and at a location close to the fixing member or the pressing member where the temperature becomes high, there is a possibility of deforming and contacting the fixing member. Providing a gap to prevent contact due to deformation leads to an increase in the size of the device. Further, providing a gap to prevent contact due to deformation makes the layer thickness of the heat insulation layer unstable and the energy efficiency unstable.

[0010] In Patent Document 3, the heat insulation member is composed of a sheet material in which resin is mixed with polyester fiber, and the thickness is set to 1 mm or more. Such a heat insulation member has a large thickness for arranging it according to a complicated shape, is not suitable for miniaturizing the device, and leads to an increase in the size of the device.

[0011] In Patent Document 4, examples of the heat insulation member include a heat insulation sheet or a porous mat processed into a sheet shape in which silica aerogel is impregnated in fibers, and those having a thermal conductivity of 0.01 to 0.035 W / mK are exemplified. Although a single layer and a laminated one are disclosed as the heat insulation member, in any case, the total layer thickness is 2 mm or more, and it does not have a configuration that covers the entire surface of the rotating member. In this configuration, the radiation from the rotating member cannot be efficiently reflected by the heat insulation member, and the effect of reducing the power consumption to the heat source is insufficient.

[0012] Therefore, an object of the present invention is to provide a fixing device that enhances the effect of reducing power consumption without increasing the size of the device.

Means for Solving the Problems

[0013] In order to solve the above problems, a fixing device of the present invention is a fixing device that fixes a toner image on a recording medium to the recording medium, and includes two rotating bodies that are in contact with each other to form a nip portion, heating means for heating at least one of the two rotating bodies, a heat insulating member disposed opposite to at least one of the two rotating bodies, and a sheet member provided in contact with the heat insulating member, wherein the sheet member contains silica aerogel and has a thickness of less than 1 mm.

Effects of the Invention

[0014] According to the present invention, it is possible to provide a fixing device that enhances the effect of reducing power consumption without increasing the size of the device.

Brief Description of the Drawings

[0015]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Embodiments for Carrying Out the Invention

[0016] Hereinafter, the fixing device and the image forming apparatus according to the present invention will be described with reference to the drawings. Note that the present invention is not limited to the embodiments shown below, and can be changed within the scope that those skilled in the art can conceive, such as other embodiments, additions, modifications, deletions, etc., and as long as the functions and effects of the present invention are achieved in any aspect, it is included in the scope of the present invention.

[0017] The fixing device of the present invention is a fixing device that fixes a toner image on a recording medium, and includes two rotating bodies that abut against each other to form a nip portion, heating means for heating at least one of the two rotating bodies, a heat insulating member disposed to face at least one of the two rotating bodies, and a sheet member provided in contact with the heat insulating member. The sheet member includes silica aerogel and has a thickness of less than 1 mm.

[0018] Further, the image forming apparatus of the present invention is characterized by including the fixing device of the present invention.

[0019] According to the present invention, it is possible to provide a fixing device and an image forming apparatus that enhance the effect of reducing power consumption without increasing the size of the apparatus. In one embodiment of the present invention, a thin member (sheet member) made of sheet-shaped silica aerogel is provided on the entire surface on the rotating body side of a heat insulating cover (heat insulating member) provided to face at least one of the two rotating bodies that form a nip portion. Thereby, a fixing device with a high effect of reducing the power consumption of the heat source (heating means) can be obtained. Further, it is more preferable to provide the sheet member on the entire surface of the facing surface of the heat insulating member with the rotating body. In this case, the effect of reducing the power consumption of the heat source can be enhanced.

[0020] The image forming apparatus of this embodiment will be described. The image forming apparatus of this embodiment can be applied to a laser printer (sometimes referred to as a printer), which is an electrophotographic image forming apparatus. Hereinafter, an embodiment applied to a laser printer will be described.

[0021] FIG. 1 is a schematic configuration diagram of an image forming apparatus according to an embodiment of the present invention.

[0022] The image forming apparatus 100 shown in FIG. 1 includes four image forming units 1Y, 1M, 1C, and 1Bk that are detachable from the image forming apparatus main body. Each of the image forming units 1Y, 1M, 1C, and 1Bk has the same configuration except that it contains different color developers of yellow, magenta, cyan, and black corresponding to the color separation components of a color image. Specifically, each of the image forming units 1Y, 1M, 1C, and 1Bk includes a drum-shaped photoreceptor 2 as an image carrier, a charging device 3 that charges the surface of the photoreceptor 2, a developing device 4 that supplies toner as a developer to the surface of the photoreceptor 2 to form a toner image, and a cleaning device 5 that cleans the surface of the photoreceptor 2.

[0023] The image forming apparatus 100 also includes an exposure device 6 that exposes the surface of each photoreceptor 2 to form an electrostatic latent image, a paper feeding device 7 that supplies paper P as a recording medium, a transfer device 8 that transfers the toner image formed on each photoreceptor 2 to the paper P, a fixing device 200 that fixes the toner image transferred to the paper P, and a paper discharging device 10 that discharges the paper P outside the apparatus.

[0024] The transfer device 8 includes an endless intermediate transfer belt 11 as an intermediate transfer member stretched by a plurality of rollers, four primary transfer rollers 12 as primary transfer members that transfer the toner image on each photoreceptor 2 to the intermediate transfer belt 11, and a secondary transfer roller 13 as a secondary transfer member that transfers the toner image transferred onto the intermediate transfer belt 11 to the paper P. The plurality of primary transfer rollers 12 are each in contact with the photoreceptor 2 via the intermediate transfer belt 11. As a result, the intermediate transfer belt 11 and each photoreceptor 2 are in contact with each other, and a primary transfer nip is formed therebetween. On the other hand, the secondary transfer roller 13 is in contact with one of the rollers that stretch the intermediate transfer belt 11 via the intermediate transfer belt 11. As a result, a secondary transfer nip is formed between the secondary transfer roller 13 and the intermediate transfer belt 11.

[0025] In addition, in the image forming apparatus 100, a paper conveyance path 14 through which the paper P fed out from the paper feeding apparatus 7 is conveyed is formed. A pair of timing rollers 15 are provided midway in the paper conveyance path 14 from the paper feeding apparatus 7 to the secondary transfer nip (secondary transfer roller 13).

[0026] Next, the printing operation of the above-described image forming apparatus will be described with reference to FIG. 1.

[0027] When an instruction to start the printing operation is given, in each image forming unit 1Y, 1M, 1C, 1Bk, the photosensitive member 2 is rotationally driven clockwise in FIG. 1, and the surface of the photosensitive member 2 is charged to a uniform high potential by the charging device 3. Next, based on the image information of the original read by the original reading device or the print information instructed from the terminal, the exposure device 6 exposes the surface of each photosensitive member 2, so that the potential of the exposed portion decreases and an electrostatic latent image is formed. Then, toner is supplied from the developing device 4 to this electrostatic latent image, and a toner image is formed on each photosensitive member 2.

[0028] When the toner image formed on each photosensitive member 2 reaches the primary transfer nip (position of the primary transfer roller 12) as the photosensitive member 2 rotates, it is transferred so as to sequentially overlap the intermediate transfer belt 11 that is rotationally driven counterclockwise in FIG. 1. Then, the toner image transferred onto the intermediate transfer belt 11 is conveyed to the secondary transfer nip (position of the secondary transfer roller 13) as the intermediate transfer belt 11 rotates, and is transferred to the paper P conveyed to the secondary transfer nip. This paper P is supplied from the paper feeding apparatus 7. The paper P supplied from the paper feeding apparatus 7 is once stopped by the timing roller 15, and then is conveyed to the secondary transfer nip in accordance with the timing when the toner image on the intermediate transfer belt 11 reaches the secondary transfer nip. Thus, a full-color toner image is carried on the paper P. Also, after the toner image is transferred, the toner remaining on each photosensitive member 2 is removed by each cleaning device 5.

[0029] The sheet P onto which the toner image has been transferred is conveyed to the fixing device 200, and the toner image is fixed to the sheet P by the fixing device 200. Thereafter, the sheet P is discharged outside the apparatus by the paper discharge device 10, and a series of printing operations is completed.

[0030] FIG. 2 is a schematic diagram for explaining the fixing device 200, and is a view seen from the direction of the rotation axis of the fixing belt 21.

[0031] The fixing device 200 has two rotating bodies. The two rotating bodies in this example are the fixing belt 21 and the pressure roller 22. The fixing device 200 is configured such that the fixing belt 21, which is a rotating body, is used as a fixing member heated by a heat source (heating means).

[0032] The fixing device 200 is used to melt and penetrate the transferred toner image carried on the sheet P by heat and pressure for fixing. The fixing device 200 includes a flexible fixing belt 21 that can rotate while being heated. Note that the sheet P is an example of a recording medium, and may also be referred to as a recording material, recording paper, or the like.

[0033] In addition to the fixing belt 21, the fixing device 200 includes a pressure roller 22 and a heater 23. The pressure roller 22 is a rotating body rotatably provided facing the fixing belt 21. The heater 23 is an example of a heating means, and includes a plurality of halogen lamps 23a, 23b that heat the fixing belt 21 at locations other than the nip portion N.

[0034] Inside the fixing belt 21, a nip forming member 24, a stay 25, and a reflecting member 26 are provided. The nip forming member 24 is a base member for nip formation disposed inside the fixing belt 21. The nip forming member 24, which is a base member for nip formation, has a sliding sheet (low friction sheet) wound around a base pad, although details are not shown. The stay 25 supports the nip forming member 24. The reflecting member 26 reflects the light radiated from the heater 23 onto the fixing belt 21.

[0035] In this configuration, in order to reduce power consumption, a heat-insulating member for enhancing the heat-insulating effect is provided around each fixing member. As the heat-insulating member, a cover-shaped member can be used, and the cover-shaped member may be simply referred to as a cover, or may be referred to as a heat-insulating cover or the like. By providing the heat-insulating member, heat radiation from the fixing belt 21 and the pressure roller 22 used for fixing can be suppressed, and inadvertent heat dissipation can be prevented. As the heat-insulating members in the present embodiment, a heating heat-insulating cover 220 and a pressure heat-insulating cover 203 are used.

[0036] For the fixing belt 21, a heating heat-insulating cover 220 having a predetermined facing interval with the fixing belt 21 is provided. The heating heat-insulating cover 220 is formed of, for example, a thin metal plate. The facing surface of the heating heat-insulating cover 220 to the fixing belt 21 may be mirror-finished. By performing mirror finishing, energy-saving performance can be improved.

[0037] For the pressure roller 22, a pressure heat-insulating cover 203 having a predetermined facing interval with the pressure roller 22 is provided. The pressure heat-insulating cover 203 is, for example, a resin member. When the pressure heat-insulating cover 203 is a resin member, the surface facing the pressure roller 22 may be a reflective surface by vapor deposition or the like. By being a reflective surface, the reflection efficiency can be increased and the energy-saving performance can be improved. The pressure heat-insulating cover 203 may be a metal member. The pressure heat-insulating cover 203 may be formed of metal and the surface facing the pressure roller 22 may be mirror-finished.

[0038] Note that when using the sheet member 230 described later, it is not necessary to perform mirror finishing or form a reflective surface. By not performing mirror finishing or forming a reflective surface, the cost can be reduced.

[0039] The nip forming member 24 shown in FIG. 2 has a flat shape of the nip portion N, but is not limited to this shape. For example, the nip forming member 24 may be formed in a concave shape along the circumferential surface of the pressure roller 22. In this case, since the leading end of the paper P passing through the nip portion N approaches the pressure roller 22 side, the separability from the fixing belt 21 is improved.

[0040] The temperature of the fixing belt 21 is detected by a temperature sensor 27 provided on the side where the paper P enters the nip portion, and is used for the feedback processing of the heater 23. In FIG. 2, the arrow F indicates the conveyance direction of the paper P.

[0041] The fixing belt 21 is an endless belt formed in a thin and flexible sleeve shape, and is composed of a base material and a release layer located on its surface. For the base material, a metal material such as nickel or SUS, or a resin material such as polyimide is used. For the release layer, a tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer (PFA) or polytetrafluoroethylene (PTFE) having releasability with respect to toner is used.

[0042] The pressure roller 22 in this example is composed of a core metal 22a, an elastic layer 22b, and a release layer 22c. The elastic layer 22b is made of, for example, foamed silicone rubber, silicone rubber, or fluorine rubber provided on the surface of the core metal 22a. The release layer 22c is made of, for example, PFA or PTFE provided on the surface of the elastic layer 22b.

[0043] The pressure roller 22 is pressurized toward the fixing belt 21 by a pressurizing mechanism 204 and abuts against the fixing belt 21. The nip forming member 24 is used as a base member and abuts against the fixing belt 21.

[0044] At the location where the pressure roller 22 and the fixing belt 21 are in contact, the elastic layer 22b of the pressure roller 22 is crushed. As a result, the nip forming member 24 receives pressure between it and the fixing belt 21, and a nip portion N with a predetermined width is secured.

[0045] The pressure roller 22 is configured to be rotationally driven by a drive source such as a motor (not shown) provided in the printer main body. When the pressure roller 22 is rotationally driven, its driving force is transmitted to the fixing belt 21 at the nip portion N, and the fixing belt 21 is driven to rotate passively.

[0046] In the configuration shown in FIG. 2, the pressure roller 22 is a solid roller, but it may also be a hollow roller. In that case, it is also possible to dispose a heating source (heating means) such as a halogen heater using radiant heat inside the pressure roller 22.

[0047] Also, when there is no elastic layer 22b, the heat capacity becomes small and the fixing property is improved. On the other hand, when there is no elastic layer 22b, when crushing and fixing unfixed toner, minute irregularities on the surface of the fixing belt 21 may be transferred to the image, resulting in gloss unevenness in the solid portion of the image. To prevent this, it is desirable to provide an elastic layer with a thickness of 100 μm or more.

[0048] As the pipe-shaped metal used for the hollow roller, aluminum, iron, stainless steel, etc. can be selected.

[0049] When providing a heat source inside the pressure roller 22, it is desirable to provide a heat insulating layer on the surface of the support or a heat ray reflecting surface by mirror finishing. When providing a heat insulating layer or a heat source reflecting surface, it is possible to suppress the support from being heated by the radiant heat from the heat source. The heat source is not limited to the above-described halogen heater, and it is also possible to use an IH heater, a resistance heating element, or a carbon heater.

[0050] FIGS. 3 to 5 are diagrams for showing the heat insulating cover 203. FIG. 3 is a perspective view for showing the pressing mechanism 204 used in the fixing device shown in FIG. 2. FIG. 4 is a view seen from the direction indicated by the arrow (4) in FIG. 3. FIG. 5 is a view of the heat-insulating cover 203 seen from another direction.

[0051] The heat-insulating cover 203 is a metal or resin member having a surface capable of covering the circumferential surface on the side opposite to the side facing the nip portion N in the circumferential direction of the pressure roller 22. The surface of the heat-insulating cover 203 facing the pressure roller 22 may be mirror-finished in the case of metal, or a reflective surface may be formed by vapor deposition or the like in the case of resin. By mirror-finishing or forming a reflective surface, reflected heat can be supplied to the nip portion N, and the power consumption of the heat source can be reduced.

[0052] The heat-insulating cover 203 may be connected to the pressing mechanism 204, or may be movable in conjunction with the pressing mechanism 204. The pressing mechanism 204 may be used as an approaching / separating mechanism that swingably supports the pressure roller 22 in a direction in which it can approach and separate from the fixing belt 21. For example, it can be configured as disclosed in Japanese Patent No. 6446797.

[0053] A pair of stud insertion portions 203A (see FIG. 5) to be inserted into a pair of studs 212 forming a connecting portion fixed to the pressing mechanism 204 side may be provided in a part of the heat-insulating cover 203. The stud 212 may swing with respect to the substrate 204A integrally with the pressure roller biasing plate 204B. The heat-insulating cover 203 may be movable in the approaching / separating direction while maintaining the facing interval with the pressure roller 22 in accordance with the approaching / separating operation of the pressure roller 22.

[0054] The heat-insulating cover 203 may be used as a support portion for a member that needs to maintain the facing relationship with the pressure roller 22.

[0055] Next, a detailed example of this embodiment will be described with reference to FIGS. 2, 6, and 7. FIGS. 6 and 7 are enlarged views of the main part of FIG. 2.

[0056] The fixing device of this embodiment includes two rotating bodies, a heating means, a heat insulation member, and a sheet member. The two rotating bodies are in contact with each other to form a nip portion N. The two rotating bodies in this embodiment are a fixing belt 21 and a pressure roller 22.

[0057] The heating means heats at least one of the two rotating bodies. The heating means in this embodiment is a heater 23. The heater 23 is provided inside the fixing belt 21 and heats the fixing belt 21. As described above, a heating source (heating means) may be provided on the pressure roller 22. Heating means may be provided on both the fixing belt 21 side and the pressure roller 22 side.

[0058] The heat insulation member is disposed to face at least one of the two rotating bodies. The heat insulation member may be disposed on both of the two rotating bodies respectively. In this embodiment, examples of the heat insulation member include a heating and heat insulation cover 220 and a pressure heat insulation cover 203. The heating and heat insulation cover 220 is disposed to face the fixing belt 21. The pressure heat insulation cover 203 is disposed to face the pressure roller 22.

[0059] The sheet member is provided in contact with the heat insulation member. In this embodiment, examples of the sheet member include a sheet member 230a and a sheet member 230b. The sheet member 230a is provided in contact with the heating and heat insulation cover 220. The sheet member 230b is provided in contact with the pressure heat insulation cover 203. When the sheet member 230a and the sheet member 230b are described without distinction, they may be referred to as the sheet member 230 or the like.

[0060] In this embodiment, the heating and heat-insulating cover 220 and the pressurizing and heat-insulating cover 203 are provided with a sheet member. The sheet member 230 contains silica aerogel and has a thickness of less than 1 mm. By including silica aerogel in the sheet member 230, the heat insulation effect can be enhanced. By providing the sheet member 230a on the heating and heat-insulating cover 220, the heat preservation effect of the fixing belt 21 can be enhanced, and the power consumption of the heat source can be reduced. By providing the sheet member 230b on the pressurizing and heat-insulating cover 203, the heat preservation effect of the pressurizing roller 22 can be enhanced, and the power consumption of the heat source can be reduced.

[0061] Since the thickness of the sheet member 230 is less than 1 mm, it can be provided along the heat-insulating member. Further, the sheet member 230 can be adhered and attached to the heat-insulating member, and the heat insulation property can be enhanced without causing an increase in the size of the apparatus. In addition, since the sheet member 230 containing silica aerogel can be made of a flexible material, it is easy to adhere and attach it to the heat-insulating member. Even when the surface of the heat-insulating member facing the rotating body is a curved surface, the sheet member 230 can be arranged in close contact with the curved surface.

[0062] Since the sheet member 230 is in a sheet shape, it can be used along the shape of the heat-insulating member even in a narrow space, enabling effective heat insulation and preventing an increase in the size of the apparatus.

[0063] The term "Silica Aerogel" has an extremely high porosity and low density (generally 0.10 - 0.20 g / cm 3It is often used as a general term for silica gels with a certain degree. The high heat insulation performance of silica aerogel is derived from its fine structure. Silica aerogel has a low density and a small proportion of solid parts, resulting in less heat conduction through the silica skeleton. Also, the average pore diameter is about several tens of nanometers, which is less than the average free path of the main gas molecules in the air near normal temperature and pressure, so heat transfer by air convection is also suppressed. As the density increases, heat conduction increases, and as the density becomes extremely small, the average pore diameter becomes large and heat transfer by convection increases, so there is a density at which heat transfer is minimized. Generally, as described above, those with a density of 0.10~0.20 g / cm 3 are used for heat insulation materials.

[0064] Regarding silica aerogel, for example, the following documents are also reference. https: / / www.jstage.jst.go.jp / article / seikeikakou / 22 / 11 / 22_616 / _pdf / -char / ja https: / / www.kri-inc.jp / press / 1277364_11456.html https: / / www.hirose-paper-mfg.co.jp / products / list / os /

[0065] In recent years, by combining silica aerogel with cellulose or fibers, it has become possible to form a heat insulation sheet that is as thin as paper and lighter than paper. Therefore, by combining such a member with the fixing device of an electrophotographic apparatus, partial heat insulation becomes possible, and an energy-saving fixing device and an image forming apparatus using the same can be provided without increasing the size of the apparatus.

[0066] In this embodiment, the prescription of the sheet member 230 only needs to contain silica aerogel and can be appropriately selected. For example, the sheet member 230 uses a member that combines silica aerogel with cellulose or fibers. The thermal conductivity of the sheet member 230 can be appropriately selected. For example, by setting the thermal conductivity to 0.01 - 0.03 [W / m·K], a good heat insulation effect can be ensured.

[0067] The thickness of the sheet member 230 only needs to be less than 1 mm. In this example, it is set to 0.3 mm, for example. The lower limit is not particularly limited, but it is preferably 0.1 mm or more, for example. In this case, the handling during manufacturing can be improved.

[0068] As shown in FIG. 6, the sheet member 230a is provided on the side facing the fixing belt 21 of the heat-insulating cover 220. That is, as shown in the figure, the heat-insulating cover 220 has a facing surface facing the fixing belt 21, and the sheet member 230a is preferably provided in contact with the facing surface. In other words, it can also be said that the facing surface of the heat-insulating cover 220 faces the fixing belt 21 through the sheet member 230a. By arranging it in such a way, the heat insulation effect can be further enhanced.

[0069] As shown in the figure, the sheet member 230a is preferably provided on the entire facing surface of the heat-insulating cover 220 facing the fixing belt 21. By setting the range where the sheet member 230a is provided in this way, the heat insulation effect can be further enhanced.

[0070] The heating and heat preservation cover 220 is a heat preservation cover having a curved surface along the outer peripheral surface of the fixing belt 21 as shown in the figure. Since the heating and heat preservation cover 220 is such a heat preservation cover, the heat preservation effect of the fixing belt 21 can be further enhanced. Also, as shown in the figure, the opposing surface of the heating and heat preservation cover 220 to the fixing belt 21 has a rectangular portion in addition to the curved surface, and the sheet member 230a in the present embodiment can be provided along such a rectangular portion. Therefore, even if the heating and heat preservation cover 220 has a complicated shape, the sheet member 230a can be provided in close contact therewith.

[0071] The sheet member 230a is provided along the opposing surface (curved surface) to the fixing belt 21 in the heating and heat preservation cover 220. The method of providing the sheet member 230a in contact with the heating and heat preservation cover 220 is not particularly limited. In this example, the sheet member 230a is attached to the entire opposing surface in the heating and heat preservation cover 220.

[0072] As shown in FIG. 7, the sheet member 230b is provided on the side facing the pressure roller 22 of the pressure and heat preservation cover 203. That is, as shown in the figure, the pressure and heat preservation cover 203 has an opposing surface facing the fixing belt 21, and the sheet member 230a is preferably provided in contact with the opposing surface. In other words, it can be said that the opposing surface of the pressure and heat preservation cover 203 faces the pressure roller 22 via the sheet member 230b. By arranging it in such a manner, the heat insulation effect can be further enhanced.

[0073] As shown in the figure, the sheet member 230b is preferably provided on the entire opposing surface to the pressure roller 22 in the pressure and heat preservation cover 203. By setting the range where the sheet member 230b is provided in this way, the heat insulation effect can be further enhanced.

[0074] The pressure-holding and heat-insulating cover 203 is a heat-insulating cover having a curved surface along the outer peripheral surface of the fixing belt 21 as shown in the figure. Since the pressure-holding and heat-insulating cover 203 is such a heat-insulating cover, the heat-insulating effect of the fixing belt 21 can be further enhanced. Also, as shown in the figure, the surface of the pressure-holding and heat-insulating cover 203 on the side of the pressure roller 22 has a flat portion in addition to the curved surface, and the sheet member 230b in the present embodiment can be provided along such a rectangular portion. Therefore, even if the pressure-holding and heat-insulating cover 203 has a complicated shape, the sheet member 230b can be provided in close contact therewith.

[0075] The sheet member 230b is provided along the opposing surface (curved surface) of the pressure-holding and heat-insulating cover 203 with the pressure roller 22. The method of providing the sheet member 230b in contact with the pressure-holding and heat-insulating cover 203 is not particularly limited. In this example, the sheet member 230b is attached to the entire opposing surface of the pressure-holding and heat-insulating cover 203.

[0076] As shown in FIG. 2, it is preferable that the fixing device 200 is provided with both the heating and heat-insulating cover 220 and the pressure-holding and heat-insulating cover 203. That is, when two rotating bodies are defined as a first rotating body and a second rotating body, it is preferable that the heat-insulating member is provided on both the first rotating body and the second rotating body. By doing so, both the heat-insulating effect of the fixing belt 21 and the heat-insulating effect of the pressure roller 22 can be enhanced, and the power consumption of the entire device can be further reduced.

[0077] As shown in FIG. 2, it is preferable that the fixing device 200 is provided with both the sheet member 230a and the sheet member 230b. That is, when the heat-insulating member provided on the first rotating body side is defined as a first heat-insulating member and the heat-insulating member provided on the second rotating body side is defined as a second heat-insulating member, it is preferable that the sheet member is provided on both the first heat-insulating member and the second heat-insulating member. By doing so, both the heat-insulating effect of the fixing belt 21 and the heat-insulating effect of the pressure roller 22 can be further enhanced, and the power consumption of the entire device can be further reduced.

[0078] As shown in FIG. 2, in the fixing device 200, it is preferable that both the sheet member 230a and the sheet member 230b are provided in contact with the opposing surface of the rotating body in the heat-insulating member. That is, the first heat-insulating member has a first surface facing the first rotating body, the second heat-insulating member has a second surface facing the second rotating body, the sheet member provided in the first heat-insulating member is defined as the first sheet member, the sheet member provided in the second heat-insulating member is defined as the second sheet member, the first sheet member is provided in contact with the entire surface of the first surface, and the second sheet member is preferably provided in contact with the entire surface of the second surface. By doing so, the heat-insulating effect of the fixing belt 21 and the heat-insulating effect of the pressure roller 22 can be further enhanced, and the power consumption of the entire device can be further reduced.

[0079] The pressure-heat-insulating cover 203 may be made of, for example, metal or resin as described above. When the pressure-heat-insulating cover 203 is made of resin, the temperature rise of the resin-made pressure-heat-insulating cover 203 itself can be suppressed by providing the sheet member 230b. Thereby, deformation of the resin-made pressure-heat-insulating cover 203 can be suppressed.

[0080] In the fixing device shown in FIG. 2, in which the sheet member 230a is provided on the heating-heat-insulating cover 220 and the sheet member 230b is provided on the pressure-heat-insulating cover 203, an evaluation was made regarding power consumption. The thickness of the sheet member 230 is set to 0.3 mm. As a result, the TEC value (Typical Electricity Consumption), which is an index of energy saving, was reduced by 3.4% compared to the fixing device in which neither the sheet member 230a nor the sheet member 230b was provided.

[0081] In this way, the fixing device of the present embodiment can enhance the effect of reducing power consumption without increasing the size of the device. Further, since the image forming apparatus of the present embodiment includes the fixing device of the present embodiment, the effect of reducing power consumption can be enhanced.

[0082] In this embodiment, by using the sheet member 230, the power consumption of the heat source can be reduced. Therefore, even if the facing surface of the fixing belt 21 in the heating and heat-insulating cover 220 is not mirror-finished, the power consumption of the heat source can be reduced, and cost reduction is possible. Similarly, even if the facing surface of the pressure roller 22 in the pressure and heat-insulating cover 203 is not mirror-finished or a reflecting surface is not formed, the power consumption of the heat source can be reduced, and cost reduction is possible. The fixing device and the image forming device of this embodiment can enhance energy saving and can be devices with a good cost balance.

[0083] Aspects of the present invention are, for example, as follows. <1> A fixing device for fixing a toner image on a recording medium to the recording medium, comprising: Two rotating bodies that contact each other to form a nip portion; Heating means for heating at least one of the two rotating bodies; A heat-insulating member disposed to face at least one of the two rotating bodies; A sheet member provided in contact with the heat-insulating member, wherein the sheet member contains silica aerogel and has a thickness of less than 1 mm The fixing device is characterized by this. <2> The heat-insulating member has a facing surface facing one of the two rotating bodies, The sheet member is provided in contact with the facing surface The fixing device according to <1>, characterized by this. <3> The sheet member is provided on the entire surface of the facing surface The fixing device according to <2>, characterized by this. <4> When the two rotating bodies are a first rotating body and a second rotating body, The heat-insulating member is provided on both the first rotating body and the second rotating body The fixing device according to any one of <1> to <3>, characterized by this. <5> The heat-insulating member provided on the first rotating body side is defined as a first heat-insulating member, The heat-insulating member provided on the second rotating body side is defined as a second heat-insulating member, The sheet member is provided on both the first heat-insulating member and the second heat-insulating member The fixing device according to <4>, characterized in that. <6> The first heat-insulating member has a first surface facing the first rotating body, The second heat-insulating member has a second surface facing the second rotating body, The sheet member provided on the first heat-insulating member is defined as a first sheet member, The sheet member provided on the second heat-insulating member is defined as a second sheet member, The first sheet member is provided in contact with the first surface, The second sheet member is provided in contact with the second surface The fixing device according to <4> or <5>, characterized in that. <7> The heat-insulating member is a heat-insulating cover having a curved surface along the outer peripheral surface of one of the two rotating bodies The fixing device according to any one of <1> to <6>, characterized in that. <8> Comprising the fixing device according to any one of <1> to <7> The image forming apparatus, characterized in that.

Explanation of reference numerals

[0084] 21 Fixing belt 22 Pressing roller 23 Heater 24 Nip forming member 25 Stay 203 Pressing heat-insulating cover 220 Heating heat-insulating cover 230a, 230b Sheet member

Prior art documents

Patent documents

[0085] [Patent Document 1] Japanese Patent No. 6446797 [Patent Document 2] Japanese Unexamined Patent Application Publication No. 2003-345155 [Patent Document 3] Japanese Unexamined Patent Application Publication No. 2004-126175 [Patent Document 4] Japanese Unexamined Patent Application Publication No. 2021-60434

Claims

1. A fixing device for fixing a toner image on a recording medium, comprising: Two rotating bodies that are in contact with each other to form a nip portion; Heating means for heating at least one of the two rotating bodies; A heat-insulating member disposed opposite to at least one of the two rotating bodies; A sheet member provided in contact with the heat-insulating member, wherein the sheet member contains silica aerogel and has a thickness of less than 1 mm The fixing device is characterized by that.

2. The heat-insulating member has a facing surface facing one of the two rotating bodies, The sheet member is provided in contact with the facing surface The fixing device according to claim 1, characterized by that.

3. The sheet member is provided over the entire surface of the facing surface The fixing device according to claim 2, characterized by that.

4. When the two rotating bodies are a first rotating body and a second rotating body, The heat-insulating member is provided on both the first rotating body and the second rotating body The fixing device according to claim 1, characterized by that.

5. The heat-insulating member provided on the first rotating body side is a first heat-insulating member, The heat-insulating member provided on the second rotating body side is a second heat-insulating member, The sheet member is provided on both the first heat-insulating member and the second heat-insulating member The fixing device according to claim 4, characterized by that.

6. The first heat-insulating member has a first surface facing the first rotating body, The second heat-insulating member has a second surface facing the second rotating body, The sheet member provided on the first heat-insulating member is a first sheet member, The sheet member provided on the second heat-insulating member is a second sheet member, The first sheet member is provided in contact with the entire surface of the first surface, The second sheet member is provided in contact with the entire surface of the second surface The fixing device according to claim 4, characterized by that.

7. An image forming apparatus comprising the fixing device according to any one of claims 1 to 6 The image forming apparatus is characterized by that.

Images