JP2021085930A - Belt device, fixing device, and image forming apparatus - Google Patents

Abstract

To prevent the generation of a gap between two members.SOLUTION: A belt device 9 comprises: an endless belt member 21; an opposing member 22 that is arranged opposite to an outer peripheral surface of the belt member 21; a nip forming member 24 that sandwiches the belt member 21 with the opposing member 22 to form a nip part N; a support member 25 that supports the nip forming member 24; and a resin sheet member 29 that is arranged between the nip forming member 24 and the support member 25.SELECTED DRAWING: Figure 2

Description

The present invention relates to a belt device, a fixing device and an image forming device.

For example, as a belt device mounted on an image forming device such as a copying machine or a printer, a belt-type fixing device for fixing an unfixed image on a recording medium such as paper by using an endless belt member is known.

In general, a belt-type fixing device is a nip forming member that forms a nip portion by sandwiching a fixing belt between a fixing belt, an opposing member arranged so as to face the outer peripheral surface of the fixing belt, and the opposing member. A support member for supporting the nip forming member, a heating member for heating the fixing belt, and the like are provided.

Patent Document 1 discloses a belt-type fixing device in which a heat insulating material is interposed between a nip forming member and a support member.

By the way, when a heat insulating material is interposed between the nip forming member and the supporting member, it is desired that the respective members are uniformly contacted without interposing a partial gap between the nip forming member, the heat insulating material and the supporting member. There is a request such as. However, in reality, it is difficult to form the contact surface between the heat insulating material and the nip forming member and the contact surface between the heat insulating material and the support member in a shape that completely matches. Therefore, there is a tendency for a partial gap to be formed between the nip forming member and the heat insulating material and between the heat insulating material and the support member.

In order to solve the above problems, in the present invention, the belt device places the belt member between the endless belt member, the opposing member arranged so as to face the outer peripheral surface of the belt member, and the opposing member. A nip forming member for forming a nip portion by sandwiching the nip, a support member for supporting the nip forming member, and a resin sheet member arranged between the nip forming member and the supporting member are provided.

According to the present invention, it is possible to suppress the formation of a gap between the two members.

It is a schematic block diagram of the image forming apparatus which concerns on one Embodiment of this invention. It is a schematic block diagram of the fixing device. It is a figure which shows the peripheral part of the nip part of a fixing device in an enlarged manner. It is a perspective view which shows the state which the positioning member and the nip forming member are separated. It is a perspective view which shows the state which the positioning member and the nip forming member are assembled. It is a figure which shows the structure which concerns on 2nd Embodiment of this invention. It is a figure which shows the structure which concerns on 3rd Embodiment of this invention. It is a figure which shows the structure which concerns on 4th Embodiment of this invention.

Hereinafter, the present invention will be described with reference to the accompanying drawings. In each drawing for explaining the present invention, components such as members and components having the same function or shape are once described by giving the same reference numerals as much as possible, and then the description thereof will be described. Omit.

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

The image forming apparatus 100 shown in FIG. 1 includes four image forming units 1Y, 1M, 1C, and 1Bk, which are image forming units. Each image forming unit 1Y, 1M, 1C, 1Bk is configured to be detachable from the image forming apparatus main body 103, and develops different colors of yellow, magenta, cyan, and black corresponding to the color separation component of the color image. It has the same structure except that it is housed. Specifically, each image forming unit 1Y, 1M, 1C, 1Bk is formed on a drum-shaped photoconductor 2 as an image carrier, a charging device 3 for charging the surface of the photoconductor 2, and a surface of the photoconductor 2. It includes a developing device 4 that supplies toner as a developing agent to form a toner image, and a cleaning device 5 that cleans the surface of the photoconductor 2.

Further, the image forming apparatus 100 is formed on each photoconductor 2, an exposure apparatus 6 that exposes the surface of each photoconductor 2 to form an electrostatic latent image, a paper feeding device 7 that supplies paper P as a recording medium, and each photoconductor 2. A transfer device 8 for transferring the transferred toner image to the paper P, a fixing device 9 for fixing the toner image transferred to the paper P, and a paper ejection device 10 for discharging the paper P to the outside of the device are provided.

The transfer device 8 includes an endless intermediate transfer belt 11 as an intermediate transfer body stretched by a plurality of rollers, and four primary transfer members for transferring a toner image on each photoconductor 2 to the intermediate transfer belt 11. It has a primary transfer roller 12 and a secondary transfer roller 13 as a secondary transfer member that transfers the toner image transferred on the intermediate transfer belt 11 to the paper P. Each of the plurality of primary transfer rollers 12 is in contact with the photoconductor 2 via the intermediate transfer belt 11. As a result, the intermediate transfer belt 11 and each photoconductor 2 come into contact with each other, and a primary transfer nip is formed between them. On the other hand, the secondary transfer roller 13 is in contact with one of the rollers for tensioning 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.

Further, in the image forming apparatus 100, a paper conveying path 14 for conveying the paper P sent out from the paper feeding device 7 is formed. A pair of timing rollers 15 are provided on the way from the paper feeding device 7 to the secondary transfer nip (secondary transfer roller 13) in the paper transport path 14.

Next, the printing operation of the image forming apparatus will be described with reference to FIG.

When instructed to start the printing operation, in each of the image forming units 1Y, 1M, 1C, and 1Bk, the photoconductor 2 is rotationally driven clockwise in FIG. 1, and the charging device 3 causes the surface of the photoconductor 2 to have a uniform height. It is charged to the electric potential. Next, the exposure device 6 exposes the surface of each photoconductor 2 based on the image information of the document read by the document reader or the print information instructed to print from the terminal, so that the potential of the exposed portion is increased. It is lowered to form an electrostatic latent image. Then, toner is supplied from the developing device 4 to the electrostatic latent image, and a toner image is formed on each photoconductor 2.

When the toner image formed on each photoconductor 2 reaches the primary transfer nip (position of the primary transfer roller 12) as each photoconductor 2 rotates, the intermediate transfer belt is rotationally driven counterclockwise in FIG. It is transferred to 11 so as to sequentially overlap. 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 conveyed at the secondary transfer nip. Transferred to paper P. This paper P is supplied from the paper feeding device 7. The paper P supplied from the paper feeding device 7 is temporarily stopped by the timing roller 15 and then conveyed to the secondary transfer nip at the timing when the toner image on the intermediate transfer belt 11 reaches the secondary transfer nip. Thus, a full-color toner image is supported on the paper P. Further, after the toner image is transferred, the toner remaining on each photoconductor 2 is removed by each cleaning device 5.

The paper P on which the toner image is transferred is conveyed to the fixing device 9, and the toner image is fixed on the paper P by the fixing device 9. After that, the paper P is ejected to the outside of the output device 10 to complete a series of printing operations.

Subsequently, the configuration of the fixing device 9 will be described.

As shown in FIG. 2, the fixing device 9 according to the present embodiment includes a fixing belt 21, a pressure roller 22, a halogen heater 23, a nip forming member 24, a stay 25, a positioning member 26, and a reflective member. 27, a belt support member 28, and a seat member 29 are provided.

The fixing belt 21 is a fixing member that is arranged on the side of the paper P on which the unfixed image is supported and fixes the unfixed image T to the paper P. The fixing belt 21 is composed of an endless belt member (including a film). The belt member constituting the fixing belt 21 has, for example, a polyimide tubular substrate having an outer diameter of 25 mm and a thickness of 40 to 120 μm. Further, on the outermost surface layer of the fixing belt 21, fluorine such as PFA (tetrafluoroethylene / perfluoroalkyl vinyl ether copolymer) or PTFE (polytetrafluoroethylene) is used to enhance durability and ensure releasability. A release layer having a thickness of 5 to 50 μm is formed by the based resin. An elastic layer made of rubber or the like having a thickness of 50 to 500 μm may be provided between the substrate and the release layer. The substrate of the fixing belt 21 is not limited to polyimide, and may be a heat-resistant resin such as PEEK (polyetheretherketone) or a metal substrate such as nickel (Ni) or SUS. The inner peripheral surface of the fixing belt 21 may be coated with polyimide, PTFE or the like as a sliding layer.

The pressure roller 22 is an opposing member arranged so as to face the outer peripheral surface of the fixing belt 21. The pressure roller 22 has, for example, an outer diameter of 25 mm, and is composed of a solid iron core metal, an elastic layer formed on the surface of the core metal, and a release layer formed on the outside of the elastic layer. ing. The elastic layer is made of silicone rubber and has a thickness of, for example, 3.5 mm. It is desirable to use sponge rubber for the elastic layer to improve the heat insulating property of the pressure roller 22. In that case, the heat of the fixing belt 21 is less likely to be taken away by the pressurizing roller 22, and the thermal efficiency of the fixing belt 21 is improved. Further, the elastic layer may be solid rubber. In order to improve the releasability, it is desirable that a releasable layer made of a fluororesin layer having a thickness of, for example, about 40 μm is formed on the surface of the elastic layer.

The pressure roller 22 is pressed against the fixing belt 21 by a pressure means such as a spring, so that a nip portion N is formed between the fixing belt 21 and the pressure roller 22. Further, the pressurizing roller 22 is configured to be rotationally driven by a drive source provided in the image forming apparatus main body. In this embodiment, a hollow roller is used as the pressure roller 22. However, the pressure roller 22 may be a solid roller. When the pressurizing roller 22 is a hollow roller, a heating member such as a halogen heater can be arranged inside the pressurizing roller 22.

The halogen heater 23 is a heating member that heats the fixing belt 21 by radiant heat by radiating heat and light (for example, infrared light). The halogen heater 23 is arranged inside the fixing belt 21 so as to directly face the inner peripheral surface of the fixing belt 21. Further, as the heating member, other heaters such as a carbon heater, an IH coil, and a resistance heating element may be used in addition to the halogen heater 23. The fixing belt 21 is heated by the halogen heater 23, and the paper P carrying the unfixed image T is conveyed between the pressurizing roller 22 that is rotationally driven and the fixing belt 21 that is driven by the rotation (nip portion N). Then, the paper P is pressurized and heated in the nip portion N, and the unfixed image T is fixed to the paper P.

The nip forming member 24 is a member that forms the nip portion N by sandwiching the fixing belt 21 with the pressure roller 22. The nip forming member 24 is provided inside the fixing belt 21 in a longitudinal shape in the direction of the rotation axis of the fixing belt 21. When the pressurizing roller 22 is pressurized to the nip forming member 24 side by a pressurizing means such as a spring, the pressurizing roller 22 contacts (presses) the nip forming member 24 via the fixing belt 21. As a result, the nip portion N is formed between the pressure roller 22 and the fixing belt 21.

The nip forming member 24 is made of a material having a higher thermal conductivity than the stay 25 and the sheet member 29 in order to suppress the occurrence of temperature unevenness. That is, since the nip forming member 24 is made of a material having high thermal conductivity, heat can be easily transferred in the nip forming member 24, and the temperature can be made uniform. As the material of the nip forming member 24, a metal material such as aluminum, copper, iron, gold, or silver, an alloy thereof, or graphite can be used.

Further, the nip forming member 24 is configured by, for example, bending a plate material having a thickness of 0.4 to 1 mm. As shown in FIG. 3, in the present embodiment, the nip forming member 24 has a base portion 24a and two rising portions 24b and 24c. The base portion 24a is a portion having a nip forming surface 24d that contacts the inner peripheral surface of the fixing belt 21 and forms the nip portion N. One of the two rising portions is an upstream rising portion 24b provided at the upstream end portion of the base portion 24a in the paper transport direction (recording medium transport direction) Y. The other is a downstream rising portion 24c provided at the downstream end of the base portion 24a in the paper transport direction Y. Both of the rising portions 24b and 24c are provided so as to rise from the base portion 24a toward the side opposite to the pressure roller 22 side.

Further, in order to reduce the sliding resistance of the fixing belt 21 with respect to the nip forming member 24, a coating layer having excellent slidability may be formed on the surface of the nip forming member 24 on the fixing belt 21 side (nip forming surface 24d). .. Examples of the material of the coating layer include a polyimide resin, a fluororesin, a polyphenylene sulfide resin, and a saturated polyester resin. Further, glass fiber, carbon, graphite, graphite fluoride, carbon fiber, molybdenum disulfide and the like may be mixed with such a resin. Further, as the material of the coating layer, molybdenum disulfide, nickel, composite plating of nickel and fluororesin, alumite, or alumite impregnated with resin or metal can also be used. Further, as the material of the coating layer, silicon carbide ceramic, silicon nitride ceramic, alumina ceramic, or a mixture of these with molybdenum disulfide and fluororesin may be used.

The stay 25 is a support member that is arranged inside the fixing belt 21 and supports the nip forming member 24 against the pressing force of the pressure roller 22. Here, "supporting" the nip forming member 24 means that the nip forming member 24 is in contact with the nip forming member 24 on the side opposite to the pressure roller 22 side, and the nip forming member 24 is bent by the pressure from the pressure roller 22. In particular, it refers to suppressing bending of the nip forming member 24 in the pressurizing direction in the longitudinal direction.

The stay 25 comes into contact with the surface of the nip forming member 24 that contacts the fixing belt 21 on the side opposite to the surface of the nip forming member 24 via the positioning member 26 and the seat member 29. Further, the stays 25 are continuously provided along the rotation axis direction of the fixing belt 21 or the longitudinal direction of the nip forming member 24. In this way, the stay 25 is in contact with the nip forming member 24 in the longitudinal direction of the nip forming member 24, so that the bending of the nip forming member 24 in the pressurizing direction is suppressed and the width is uniform. The nip portion N is obtained. The stay 25 is preferably formed of an iron-based metal material such as SUS or SECC in order to secure its rigidity.

The positioning member 26 is a member that is arranged between the nip forming member 24 and the stay 25 and positions the nip forming member 24 with respect to the stay 25. The positioning member 26 is formed by bending a plate-shaped member or the like. The detailed configuration and positioning structure of the positioning member 26 will be described later.

The reflective member 27 is a member that reflects at least one of heat and light radiated from the halogen heater 23. The reflective member 27 is arranged inside the fixing belt 21 between the halogen heater 23 and the stay 25. By arranging the reflecting member 27 at such a position, the heat or light radiated from the halogen heater 23 is reflected by the reflecting member 27 to the fixing belt 21. As a result, the fixing belt 21 can be efficiently heated. Further, the reflective member 27 shields the heat or light applied to the stay 25, thereby suppressing unnecessary heat energy consumption and improving energy saving.

The belt support member 28 is a member that is arranged on both ends of the fixing belt 21 in the rotation axis direction and rotatably supports the fixing belt 21. The belt support member 28 has a C-shaped or tubular support portion 28a that is inserted inside the fixing belt 21. By inserting the support portion 28a inside the fixing belt 21, the fixing belt 21 is supported by a so-called free belt method in which tension in the circumferential direction basically does not act when the belt is not rotating.

The seat member 29 is arranged between the nip forming member 24 and the positioning member 26. The sheet member 29 is made of resin and is made of a foamed resin sheet having flexibility and elasticity. The material of the sheet member 29 includes PI (polyimide), PAI (polyamideimide), LCP (liquid crystal polymer), PEEK (polyetheretherketone), PEK (polyetherketone), PPS (polyphenylene sulfide), and PTFE (polytetratetra. Fluoroethylene), PFA (tetrafluoroethylene / perfluoroalkyl vinyl ether copolymer), or those containing a filler in these materials can be mentioned. Among these, PI having excellent heat resistance is particularly preferable.

FIG. 4 is a perspective view showing a state in which the positioning member 26 and the nip forming member 24 are separated, and FIG. 5 is a perspective view showing a state in which the positioning member 26 and the nip forming member 24 are assembled. In addition, in FIGS. 4 and 5, the sheet member 29 interposed between the positioning member 26 and the nip forming member 24 is omitted.

As shown in FIGS. 4 and 5, the positioning member 26 has a base portion 26a, a projecting piece portion 26b, an upstream side rising portion 26c, and a downstream side rising portion 26d. The projecting piece portion 26b rises on the downstream end side of the base portion 26a in the paper transport direction Y on the side opposite to the pressure roller 22 side (left direction in FIG. 4), and is bent so that the tip side is folded back. .. The downstream side rising portion 26d is provided so as to rise from the base portion 26a on the downstream side in the paper transport direction Y with respect to the projecting piece portion 26b on the side opposite to the pressure roller 22 side. The upstream side rising portion 26c is provided so as to rise from the base portion 26a on the upstream end side of the base portion 26a in the paper transport direction Y on the side opposite to the pressure roller 22 side. Further, a bent portion 26f formed so as to bend toward the upstream side in the paper transport direction Y is provided on the tip end side of the upstream side rising portion 26c.

As shown in FIG. 3, when the positioning member 26 and the nip forming member 24 are assembled, the downstream rising portion 26d of the positioning member 26 comes into contact with the downstream rising portion 24c of the nip forming member 24, and the positioning member The tip of the bent portion 26f of 26 comes into contact with the upstream rising portion 24b of the nip forming member 24. By these contacts, the movement of the nip forming member 24 in the paper transport direction Y with respect to the positioning member 26 is restricted. Further, in this state, the engaging projection 26g (see FIG. 5) provided in a part of the bent portion 26f of the positioning member 26 is formed in the engaging recess 24e provided in the upstream rising portion 24b of the nip forming member 24. By engaging, the movement of the nip forming member 24 with respect to the positioning member 26 in the longitudinal direction (belt rotation axis direction) is restricted.

Further, as shown in FIG. 3, when the positioning member 26 and the stay 25 are assembled, the downstream rising portion 26b and the upstream rising portion 26c of the positioning member 26 come into contact with both end surfaces thereof so as to sandwich the stay 25. By doing so, the movement of the positioning member 26 in the paper transport direction Y with respect to the stay 25 is restricted. Further, in this state, the protrusion 26h (see FIG. 5) provided on the base portion 26a of the positioning member 26 engages with the stay 25 in the longitudinal direction of the positioning member 26 with respect to the stay 25 (belt rotation axis direction). Movement is restricted.

As described above, by restricting the movement of the positioning member 26, the nip forming member 24, and the stay 25 in each direction, the nip forming member 24 and the stay 25 are positioned via the positioning member 26.

By the way, as a belt type fixing device different from the fixing device according to the above-described embodiment, there is one in which the nip forming member is made of a resin material. This nip forming member not only has a role of forming a nip portion by receiving pressure from a pressure roller, but also has a role of a heat insulating effect of suppressing heat transfer to a stay. That is, the presence of the nip forming member having a low heat transfer coefficient between the fixing belt and the stay suppresses the transfer of heat from the fixing belt to the stay. As a result, the fixing belt can be effectively heated, the first print time can be shortened, and the energy saving effect can be improved.

However, in the configuration using such a resin nip forming member, although the heat insulating effect is high, there is a problem that the temperature tends to rise in the non-paper-passing region of the fixing belt during continuous printing. On the other hand, when a nip forming member having a high thermal conductivity is used as in the above-described embodiment, the local heat storage of the fixing belt can be dispersed to the surroundings by the nip forming member. Excessive temperature rise in the non-passing area of the fixing belt can be suppressed. However, if the nip forming member having high thermal conductivity and the stay supporting the nip forming member are held in direct contact with each other, the heat of the fixing belt is easily transferred to the stay, so that the heating efficiency and energy saving of the fixing belt are lowered. To do.

Therefore, in the above-described embodiment, in order to suppress heat transfer from the fixing belt to the stay, as shown in FIG. 2, a resin sheet member 29 is interposed between the nip forming member 24 and the positioning member 26. There is. Since the seat member 29 has a lower thermal conductivity than the nip forming member 24, the positioning member 26, and the stay 25, the seat member 29 can suppress heat transfer from the fixing belt 21 to the stay 25. As a result, the heating efficiency and energy saving of the fixing belt 21 can be improved.

Further, since the seat member 29 is a flexible and elastic sheet, when the seat member 29 is sandwiched between the nip forming member 24 and the positioning member 26, it follows the shape of the nip forming member 24 and the positioning member 26. The seat member 29 is deformed. Therefore, it is possible to suppress the formation of a partial gap between the nip forming member 24 and the positioning member 26.

If there is a partial gap between the seat member 29 and both members sandwiching the seat member 29, it becomes difficult for the air layer to transfer heat from the nip forming member 24 to the positioning member 26 and the stay 25 in the gap. On the contrary, heat is easily transferred in the part where there is no gap. Therefore, temperature unevenness may occur on the nip forming member, and the temperature unevenness may affect the fixability of the image to cause an abnormal image (glossiness unevenness or a decrease in local fixability). Further, if there is a partial gap between the two members, there is a concern that the posture and position of the members may become difficult to stabilize.

On the other hand, in the above-described embodiment, the seat member 29 is deformed according to the shapes of the nip forming member 24 and the positioning member 26, so that a partial gap can be less likely to occur. As a result, the temperature unevenness of the nip forming member 24 can be suppressed, and a good image can be obtained. In addition, the posture and position of the nip forming member 24 can be stabilized.

Further, when the sheet member 29 is made of a foamed resin sheet as in the above-described embodiment, the air bubbles in the sheet material 29 are crushed when the pressing force from the pressure roller 22 is applied. The sheet member 29 is compressed. Therefore, even when the parallelism and flatness of the surfaces of the nip forming member 24 and the positioning member 26 facing each other are slightly different, the gap between these surfaces can be filled with the compressed sheet member 29. .. Therefore, when the sheet member 29 is a foamed resin sheet, the occurrence of partial gaps can be highly suppressed.

Further, when the sheet member 29 is a foamed resin sheet, it is advantageous for miniaturization because high heat insulating property can be obtained by a large number of air bubbles existing inside although it is thin. That is, even if the seat member 29 is arranged inside the fixing belt 21, the seat member 29 hardly presses the installation space of other members, so that the fixing device can be miniaturized.

Further, in order for the seat member 29 to have appropriate elasticity (compressibility) and good flexibility, the thickness of the seat member 29 is preferably 0.1 mm or more and 2.0 mm or less. More preferably, the thickness of the sheet member 29 is 0.3 mm or more and 1.0 mm or less.

In the example shown in FIG. 3, the seat member 29 is interposed only between the base portion 24a of the nip forming member 24 and the base portion 26a of the positioning member 26. As described above, the seat member 29 includes a portion where the nip forming member 24 and the positioning member 26 are in contact with each other (in addition to a portion where they are in direct contact with each other, a portion where these are indirect contact with each other via another member is also included. Similarly, it may be arranged in a part of the area of). Further, the seat member 29 may intervene over the entire portion where the nip forming member 24 and the positioning member 26 come into contact with each other. Specifically, in the example shown in FIG. 3, the seat member 29 is added between the base portions 24a and 26a of the nip forming member 24 and the positioning member 26, and between the downstream rising portions 24c and 26d, respectively. , And may be interposed between the upstream rising portion 24b of the nip forming member 24 and the bent portion 26f of the positioning member 26. In this case, heat transfer from the nip forming member 24 to the positioning member 26 can be further suppressed.

Hereinafter, embodiments different from the above-described embodiment (first embodiment) will be described. In the following description, mainly different parts will be described, and the other parts will be the same as those in the above-described embodiment, and thus the description thereof will be omitted.

FIG. 6 shows the configuration of the second embodiment of the present invention.

As shown in FIG. 6, in the second embodiment, the resin sheet member 29 is interposed between the positioning member 26 and the stay 25. In this case, heat transfer from the positioning member 26 to the stay 25 can be effectively suppressed, and the heating efficiency and energy saving of the fixing belt 21 can be improved. Further, when the seat member 29 is compressed between the positioning member 26 and the stay 25, the seat member 29 is deformed according to the shapes of the positioning member 26 and the stay 25, so that between the positioning member 26 and the stay 25. It is possible to suppress the formation of a partial gap in the air. As a result, the temperature unevenness of the nip forming member 24 can be suppressed, and a good image can be obtained. In addition, the posture and position of the nip forming member 24 can be stabilized.

In the example shown in FIG. 6, the seat member 29 is interposed only between the base portion 26a of the positioning member 26 and the stay 25. As described above, the seat member 29 includes a portion where the positioning member 26 and the stay 25 come into contact with each other (including a portion where they come into direct contact with each other and a portion where they indirectly come into contact with each other via other members. The same shall apply hereinafter). It may be arranged in a part of the area of. Further, the seat member 29 may intervene over the entire portion where the positioning member 26 and the stay 25 come into contact with each other. Specifically, in the example shown in FIG. 6, the seat member 29 is provided between the base portion 26a and the stay 25 of the positioning member 26, and between the downstream rising portion 26d and the stay 25 of the positioning member 26. Further, it may be interposed between the upstream side rising portion 26c of the positioning member 26 and the stay 25. In this case, heat transfer from the positioning member 26 to the stay 25 can be further suppressed.

In the second embodiment, unlike the first embodiment described above, the seat member 29 is not interposed between the nip forming member 24 and the positioning member 26. Therefore, the heat transfer from the nip forming member 24 to the positioning member 26 is performed more positively than in the first embodiment. Therefore, when the improvement of heating efficiency and energy saving is emphasized, it is desirable to adopt the configuration of the first embodiment instead of the configuration of the second embodiment. However, the positioning member 26 in the second embodiment can function as an auxiliary heat equalizing member that equalizes the heat of the fixing belt 21 via the nip forming member 24. That is, in the second embodiment, since the heat of the nip forming member 24 can be further dispersed and made uniform by the positioning member 26, it is possible to more effectively suppress the local temperature rise of the fixing belt 21. Is.

FIG. 7 shows the configuration of the third embodiment of the present invention.

In the third embodiment shown in FIG. 7, a resin sheet member 29 is interposed between the nip forming member 24 and the positioning member 26 and between the positioning member 26 and the stay 25. In this case, heat transfer from the nip forming member 24 to the positioning member 26 and heat transfer from the positioning member 26 to the stay 25 can be effectively suppressed, and heating efficiency and energy saving can be further improved. Further, when each sheet member 29 is compressed, each sheet member 29 is deformed according to the shape of the member sandwiching the sheet member 29, thereby suppressing the formation of a partial gap between the members sandwiching the sheet member 29. it can. As a result, the temperature unevenness of the nip forming member 24 can be suppressed, a good image can be obtained, and the posture and position of the nip forming member 24 can be stabilized.

Further, also in the third embodiment, as in each of the above-described embodiments, the seat member 29 is a contact portion between the nip forming member 24 and the positioning member 26 and a contact portion between the positioning member 26 and the stay 25. It may intervene in a part of each or in the whole.

FIG. 8 shows the configuration of the fourth embodiment of the present invention.

In the fourth embodiment shown in FIG. 8, the positioning member 26 is omitted. Therefore, in the present embodiment, only the seat member 29 is interposed between the nip forming member 24 and the stay 25. Therefore, the seat member 29 is in direct contact with each of the nip forming member 24 and the stay 25. In this case, since the heat transfer from the nip forming member 24 to the stay 25 is effectively suppressed by the seat member 29, the heating efficiency and energy saving of the fixing belt 21 can be improved. Further, when the seat member 29 is compressed between the nip forming member 24 and the stay 25, the seat member 29 deforms according to the shapes of the nip forming member 24 and the stay 25, so that the nip forming member 24 and the stay 25 It is possible to suppress the formation of a partial gap between the two. As a result, the temperature unevenness of the nip forming member 24 can be suppressed, a good image can be obtained, and the posture and position of the nip forming member 24 can be stabilized.

Further, also in the fourth embodiment, the seat member 29 may be interposed in a part of the contact portion between the nip forming member 24 and the stay 25, or may be interposed in the entire contact portion.

In the above-described embodiment, the configuration in which the seat member 29 is interposed between the nip forming member 24 and the stay 25 has been described as an example. However, the present invention is not limited to the configuration according to the above-described embodiment, and it goes without saying that various modifications can be made without departing from the gist of the present invention. For example, the intermediate member interposed between the nip forming member 24 and the stay 25 may be a member different from the positioning member 26.

Further, the present invention can be applied to a belt device other than the fixing device, such as a conveying device that conveys the paper without fixing the image on the paper. By applying the present invention to such a belt device, it is possible to suppress the formation of a partial gap between the nip forming member and the support member supporting the nip forming member, and stabilize the posture and position of the nip forming member. It is possible to plan.

Further, the image forming apparatus to which the present invention is applied is not limited to the electrophotographic type image forming apparatus as shown in FIG. The present invention is also applicable to an inkjet image forming apparatus and other image forming apparatus.

1Y, 1M, 1C, 1Bk image formation unit (image forming unit)
9 Fixing device 19 Heating device 21 Fixing belt (belt member)
22 Pressurizing roller (opposing member)
23 Halogen heater (heating member)
24 Nip forming member 25 Stay (support member)
26 Positioning member (intermediate member)
29 Seat member

Japanese Unexamined Patent Publication No. 2016-102894

Claims (9)

Endless belt member and
Opposing members arranged to face the outer peripheral surface of the belt member and
A nip forming member that forms a nip portion by sandwiching the belt member between the opposing members and
A support member that supports the nip forming member and
A resin sheet member arranged between the nip forming member and the support member,
A belt device equipped with. The belt device according to claim 1, wherein the seat member is made of a foamed resin. The belt device according to claim 1 or 2, wherein the seat member directly contacts the nip forming member and the support member, respectively. An intermediate member is interposed between the nip forming member and the support member in addition to the seat member.
The belt device according to claim 1 or 2, wherein the seat member is arranged between any two members of the nip forming member, the intermediate member, and the support member. The belt device according to claim 4, wherein the intermediate member is a positioning member that positions the nip forming member with respect to the support member. The belt device according to any one of claims 1 to 5, wherein the thickness of the sheet member is 0.1 mm or more and 2.0 mm or less. The belt device according to any one of claims 1 to 6, wherein the nip forming member is made of a material having a higher thermal conductivity than the sheet member. A fixing device for fixing an image on a recording medium to the recording medium using the belt device according to any one of claims 1 to 7. An image forming apparatus including the belt device according to any one of claims 1 to 7 or the fixing device according to claim 8.

Images