JP2021117441A - Fixing device and image forming apparatus - Google Patents

Abstract

To introduce an improvement in concentration of load to a nip forming member.SOLUTION: A fixing device comprises: a rotatable endless fixing member; an opposing member that is in contact with an outer peripheral surface of the fixing member; a heating element for heating the fixing member; a nip forming member that is brought into contact with the opposing member from an inner peripheral side of the fixing member to form a nip part and is formed of a metal material; a support member that supports the nip forming member with a surface pressure dispersion member therebetween; and the surface pressure dispersion member that is disposed between the nip forming member and the support member. The area of a contact surface between the surface pressure dispersion member and the nip forming member is larger than the area of a contact surface between the surface pressure dispersion member and the support member.SELECTED DRAWING: Figure 7

Description

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

In an electrophotographic fixing device, a nip forming member formed of a thin metal plate material that has both heat capacity and heat equalization in order to suppress temperature unevenness in the axial direction during paper passing is transferred to a support member. A certain amount of continuous arcuate convex shape is supported by a support member provided on the cut surface in order to make the contact surface smaller for the purpose of reducing it and to avoid narrowing the central part of the nip due to bending due to pressing from the opposing member. do.

For example, in Patent Document 1, a flexible endless fixing member, a heat source for heating the fixing member, a pressure member facing the fixing member, and between the fixing member and the pressure member. In a fixing device having a nip forming member forming a nip and a support member supporting the nip forming member, the back surface of the nip forming member in contact with the support member has a non-linear shape in the longitudinal direction. It is disclosed.

However, when the support member of the nip forming member is provided with a convex shape as in Patent Document 1, if the nip forming member has a thin plate shape, there is a problem that the nip forming member is deformed due to load concentration.

An object of the present invention is to provide a fixing device capable of improving load concentration on a nip forming member.

The fixing device according to the present invention includes a rotatable endless fixing member, an opposing member that abuts on the outer peripheral surface of the fixing member, a heating element for heating the fixing member, and an inner peripheral side of the fixing member. A nip forming member made of a metal material, a support member that supports the nip forming member via a surface pressure distribution member, and the nip forming member and the supporting member. The area of the contact surface between the surface pressure dispersion member and the nip forming member is larger than the area of the contact surface between the surface pressure distribution member and the support member. , It is configured as a fixing device.

According to the present invention, it is possible to improve the load concentration on the nip forming member.

It is a figure which shows the example of the image forming apparatus in this embodiment. It is sectional drawing which shows the conventional fixing apparatus. It is a perspective view of the conventional nip forming member and a support member. It is sectional drawing which shows the fixing device in this embodiment. It is a perspective view of the nip forming member and the support member in this embodiment. It is a figure which shows the example of the conventional surface pressure dispersion member. It is a figure which shows the example of the surface pressure distribution member in this embodiment. It is a figure which shows another example of the surface pressure distribution member in this embodiment. It is a figure which shows an example of the shape which can increase the rigidity of a surface pressure distribution member as compared with a nip forming member. It is a figure which shows an example of the support member formed by the convex part which cut surface is intermittent, and a plurality of surface pressure distribution members arranged according to a convex part. It is a figure which shows an example of the fixing device provided with the heat insulating member which has a small thermal conductivity between a nip forming member and a surface pressure dispersion member. It is a figure which shows an example of the fixing device provided with the heat insulating member which has a small thermal conductivity between a nip forming member and a surface pressure dispersion member. It is a figure which shows the structural example which made the height of the cut surface of the support member shown in FIG. 10 uniform, and made the thickness of the surface pressure dispersion member different from among the plurality of surface pressure dispersion members shown in FIG. It is a figure which shows the example which creates the central convex shape with high precision while sandwiching the surface pressure reducing member of the same thickness between the support member which has the support surface of the same height and the nip forming member. It is sectional drawing which shows the outline of the fixing device which provided the heating part in the nip forming member. It is a figure which shows the structural example of the heat generating part shown in FIG.

Hereinafter, embodiments of the present invention will be described. In the present embodiment, in a fixing device used in an image forming device such as a copying machine, a printer, and a facsimile, and an image forming device provided with the fixing device, a low heat capacity is provided in order to suppress temperature unevenness in the axial direction during paper passing. The nip forming member made of a thin metal plate material that has both heat equalization has a small contact surface for the purpose of reducing heat transfer, and avoids narrowing the central part of the nip due to bending due to pressing from the opposing member. Therefore, a certain amount of continuous arcuate convex shape is supported by a support member provided on the cut surface. For example, a surface pressure distribution member is formed, which is made of a member or shape having excellent rigidity as compared with a nip forming member made of aluminum or copper, and whose contact surface with the nip forming member is larger than the area of the cut surface of the support member. Provided between the member and the support member. As a result, the concentrated load from the support member can be transmitted to the nip forming member as the load distributed by the surface pressure distributing member over the entire contact surface with the nip forming member in response to the pressing of the opposing member. It is possible to prevent plastic deformation of the forming member. The features of the present invention described above will be described in detail with reference to the following drawings.

The image forming apparatus 1 shown in FIG. 1 is a color laser printer, and four image forming portions 4Y, 4M, 4C, and 4K are provided in the center of the apparatus main body. Each image forming unit 4Y, 4M, 4C, 4K accommodates developers of different colors of yellow (Y), magenta (M), cyan (C), and black (K) corresponding to the color separation components of the color image. It has the same configuration except that it is.

Specifically, the image forming units 4Y, 4M, 4C, and 4K are formed on the drum-shaped photoconductor 5 as a latent image carrier, the charging device 6 for charging the surface of the photoconductor 5, and the surface of the photoconductor 5. A developing device 7 for supplying toner, a cleaning device 8 for cleaning the surface of the photoconductor 5, and the like are provided. In FIG. 1, only the photoconductor 5, the charging device 6, the developing device 7, and the cleaning device 8 included in the black image forming unit 4K are designated by reference numerals, and the other image forming units 4Y, 4M, and 4C have reference numerals. The code is omitted.

Below each image forming unit 4Y, 4M, 4C, 4K, an exposure apparatus 9 for exposing the surface of the photoconductor 5 is arranged. The exposure apparatus 9 has a light source, a polygon mirror, an f−θ lens, a reflection mirror, and the like, and irradiates the surface of each photoconductor 5 with laser light based on the image data.

Further, a transfer device 3 is arranged above each image forming unit 4Y, 4M, 4C, 4K. The transfer device 3 includes an intermediate transfer belt 30 as an intermediate transfer body, four primary transfer rollers 31 as primary transfer means, a secondary transfer roller 36 as a secondary transfer means, a secondary transfer backup roller 32, and the like. A cleaning backup roller 33, a tension roller 34, and a belt cleaning device 35 are provided.

The intermediate transfer belt 30 is an endless belt, and is stretched by a secondary transfer backup roller 32, a cleaning backup roller 33, and a tension roller 34. Here, the secondary transfer backup roller 32 is rotationally driven so that the intermediate transfer belt 30 orbits (rotates) in the direction indicated by the arrow in the figure.

Each of the four primary transfer rollers 31 forms an intermediate transfer nip by sandwiching an intermediate transfer belt 30 with each photoconductor 5. Further, a power supply (not shown) is connected to each primary transfer roller 31, and a predetermined DC voltage (DC) and / or AC voltage (AC) is applied to each primary transfer roller 31.

The secondary transfer roller 36 sandwiches the intermediate transfer belt 30 with the secondary transfer backup roller 32 to form a secondary transfer nip. Further, similarly to the primary transfer roller 31, a power supply (not shown) is also connected to the secondary transfer roller 36, and a predetermined DC voltage (DC) and / or AC voltage (AC) is applied to the secondary transfer roller 36. It is supposed to be done.

The belt cleaning device 35 has a cleaning brush and a cleaning blade arranged so as to come into contact with the intermediate transfer belt 30. A waste toner transfer hose (not shown) extending from the belt cleaning device 35 is connected to an inlet of a waste toner container (not shown).

A bottle accommodating portion 2 is provided on the upper part of the printer main body, and four toner bottles 2Y, 2M, 2C, and 2K for accommodating replenishing toner are detachably attached to the bottle accommodating portion 2. .. A replenishment path (not shown) is provided between each toner bottle 2Y, 2M, 2C, 2K and each of the developing devices 7, and each development is performed from each toner bottle 2Y, 2M, 2C, 2K via this replenishment path. Toner is replenished to the device 7.

On the other hand, at the lower part of the printer main body, a paper feed tray 10 containing the paper P as a recording medium, a paper feed roller 11 for carrying out the paper P from the paper feed tray 10, and the like are provided. In addition to plain paper, the recording medium includes thick paper, postcards, envelopes, thin paper, coated paper (coated paper, art paper, etc.), tracing paper, OHP sheets, and the like. Further, although not shown, a manual paper feed mechanism may be provided.

A transport path R for passing the paper P from the paper feed tray 10 through the secondary transfer nip and discharging the paper P to the outside of the apparatus is provided in the printer main body. In the transport path R, a pair of resist rollers 12 as timing rollers for transporting the paper P to the secondary transfer nip by measuring the transport timing are arranged on the upstream side in the paper transport direction from the position of the secondary transfer roller 36. ing.

Further, a fixing device 20 for fixing the unfixed image transferred to the paper P is arranged on the downstream side in the paper transport direction from the position of the secondary transfer roller 36. Further, a pair of paper ejection rollers 13 for ejecting the paper to the outside of the apparatus are provided on the downstream side of the transport path R in the paper transport direction with respect to the fixing device 20. Further, on the upper surface of the printer main body, a paper ejection tray 14 for stocking the paper ejected outside the apparatus is provided.

Subsequently, with reference to FIG. 1, the basic operation of the printer according to the present embodiment will be described. When the image-drawing operation is started, each of the photoconductors 5 in each of the image-forming units 4Y, 4M, 4C, and 4K is rotationally driven clockwise by a drive device (not shown), and the surface of each photoconductor 5 is driven by the charging device 6. Is uniformly charged to a predetermined polarity. The surface of each charged photoconductor 5 is irradiated with laser light from the exposure apparatus 9, and an electrostatic latent image is formed on the surface of each photoconductor 5. At this time, the image information to be exposed to each photoconductor 5 is monochromatic image information obtained by decomposing a desired full-color image into yellow, magenta, cyan, and black color information. By supplying toner to the electrostatic latent image formed on each photoconductor 5 in this way by each developing device 7, the electrostatic latent image is visualized (visualized) as a toner image. ..

When the image-drawing operation is started, the secondary transfer backup roller 32 is rotationally driven counterclockwise in the drawing to rotate the intermediate transfer belt 30 in the direction indicated by the arrow in the figure. Further, by applying a constant voltage or a constant current controlled voltage opposite to the charging polarity of the toner to each primary transfer roller 31, the primary transfer nip between each primary transfer roller 31 and each photoconductor 5. A transfer electric field is formed in.

After that, when the toner image of each color on the photoconductor 5 reaches the primary transfer nip as the photoconductor 5 rotates, the toner image on each photoconductor 5 is generated by the transfer electric field formed in the primary transfer nip. Is sequentially superposed on the intermediate transfer belt 30 and transferred. Thus, a full-color toner image is supported on the surface of the intermediate transfer belt 30. Further, the toner on each photoconductor 5 that could not be completely transferred to the intermediate transfer belt 30 is removed by the cleaning device 8. Then, the surface of each photoconductor 5 is statically eliminated by a static elimination device (not shown), and the surface potential is initialized.

At the lower part of the printer, the paper feed roller 11 starts rotational driving, and the paper P is sent out from the paper feed tray 10 to the transport path R. The paper P sent out to the transport path R is temporarily stopped by the resist roller 12.

After that, the rotational drive of the resist roller 12 is started at a predetermined timing, and the paper P is conveyed to the secondary transfer nip at the timing when the toner image on the intermediate transfer belt 30 reaches the secondary transfer nip. At this time, a transfer voltage having a polarity opposite to the toner charging polarity of the toner image on the intermediate transfer belt 30 is applied to the secondary transfer roller 36, whereby a transfer electric field is formed in the secondary transfer nip. .. Then, the toner image on the intermediate transfer belt 30 is collectively transferred onto the paper P by this transfer electric field. Further, the residual toner on the intermediate transfer belt 30 that could not be transferred to the paper P at this time is removed by the belt cleaning device 35, and the removed toner is conveyed to a waste toner container (not shown) and collected.

After that, the paper P is conveyed to the fixing device 20, and the toner image on the paper P is fixed to the paper P by the fixing device 20. Then, the paper P is discharged to the outside of the device by the paper ejection roller 13 and is stocked on the paper ejection tray 14.

The above description is an image forming operation when forming a full-color image on paper, but a single-color image can be formed by using any one of four image forming units 4Y, 4M, 4C, and 4K. It is also possible to form a two-color or three-color image using two or three image-forming sections.

FIG. 2 is a cross-sectional view showing a conventional fixing device, and FIG. 3 is a perspective view of a conventional nip forming member and a support member. Hereinafter, the configuration of the fixing device 20 will be described with reference to FIG.

As shown in FIG. 2, the fixing device 20 serves as a fixing belt 21 as a fixing member, a pressure roller 22 as an opposing member that abuts on the outer peripheral surface of the fixing belt 21, and a heating source for heating the fixing belt 21. From the halogen heater 23, the nip forming member 24 that abuts on the pressure roller 22 from the inner peripheral side of the fixing belt 21 to form the nip portion N, the support member 25 that supports the nip forming member 24, and the halogen heater 23. A reflecting member 26 that reflects heat to the fixing belt 21 and a shielding member 27 that shields the heat from the halogen heater 23 partially or depending on the paper passing conditions may be provided as needed. Further, a temperature sensor 28 or the like as a temperature detecting means for detecting the temperature of the fixing belt 21 is provided.

The fixing belt 21 is made of a thin and flexible endless belt member (including a film). Specifically, the fixing belt 21 is formed of a base material on the inner peripheral side formed of a metal material such as nickel or SUS or a resin material such as polyimide (PI), and a tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer (PFA). Alternatively, it is composed of a release layer on the outer peripheral side formed of polytetrafluoroethylene (PTFE) or the like. Further, an elastic layer made of a rubber material such as silicone rubber, foamable silicone rubber, or fluororubber may be interposed between the base material and the release layer.

If there is no elastic layer, the heat capacity is reduced and the fixability is improved, but when the unfixed toner is crushed and fixed, minute irregularities on the belt surface are transferred to the image and the solid part of the image becomes unevenly glossy. It can occur. In order to prevent this, it is desirable to provide an elastic layer having a thickness of 100 μm or more. By providing an elastic layer having a thickness of 100 μm or more, it is possible to absorb minute irregularities due to elastic deformation of the elastic layer, so that it is possible to avoid the occurrence of uneven gloss.

In the present embodiment, the fixing belt 21 is made thin and has a small diameter in order to reduce the heat capacity of the fixing belt 21. Specifically, the thicknesses of the base material, the elastic layer, and the release layer constituting the fixing belt 21 are set in the ranges of 20 to 50 μm, 100 to 300 μm, and 10 to 50 μm, and the overall thickness is set. It is set to 1 mm or less. The diameter of the fixing belt 21 is set to 20 to 40 mm. In order to further reduce the heat capacity, it is desirable that the thickness of the entire fixing belt 21 is 0.2 mm or less, and more preferably 0.16 mm or less. Further, it is desirable that the diameter of the fixing belt 21 is 30 mm or less.

The pressure roller 22 is provided on the surface of the core metal 22a, the elastic layer 22b made of foamable silicone rubber, silicone rubber, fluororubber or the like provided on the surface of the core metal 22a, and the PFA provided on the surface of the elastic layer 22b. Alternatively, it is composed of a release layer 22c made of PTFE or the like. The pressurizing roller 22 is pressurized to the fixing belt 21 side by a pressing means (not shown) and is in contact with the nip forming member 24 via the fixing belt 21. At the position where the pressure roller 22 and the fixing belt 21 are in pressure contact with each other, the elastic layer 22b of the pressure roller 22 is crushed to form a nip portion N having a predetermined width. It should be noted that the fixing member and the facing member are not limited to the case where they are in pressure contact with each other, and it is also possible to have a configuration in which they are simply brought into contact with each other without applying pressure.

Further, 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, the driving force is transmitted to the fixing belt 21 by the nip portion N, and the fixing belt 21 is driven to rotate.

In the present embodiment, the pressure roller 22 is a solid roller, but a hollow roller may be used. In that case, a heating source such as a halogen heater may be arranged inside the pressurizing roller 22. Further, the elastic layer 22b may be solid rubber, but if there is no heating source inside the pressure roller 22, sponge rubber may be used. Sponge rubber is more preferable because it has higher heat insulating properties and is less likely to take away heat from the fixing belt 21.

The halogen heater 23 is arranged on the inner peripheral side of the fixing belt 21 and on the upstream side of the nip portion N in the paper transport direction. The halogen heater 23 is configured to generate heat by controlling the output by a power supply unit provided in the printer main body, and the output control is performed based on the detection result of the surface temperature of the fixing belt 21 by the temperature sensor 28. Be told. By controlling the output of the heater 23 in this way, the temperature of the fixing belt 21 (fixing temperature) can be set to a desired temperature. Instead of the temperature sensor 28 that detects the temperature of the fixing belt 21, a temperature sensor (not shown) that detects the temperature of the pressurizing roller 22 is provided, and the temperature of the fixing belt 21 is determined by the temperature detected by the temperature sensor. You may try to predict.

In the present embodiment, two halogen heaters 23 are provided, but the number of halogen heaters 23 may be one or three or more depending on the size of the paper used in the printer and the like. Further, as a heating source for heating the fixing belt 21, a resistance heating element, a carbon heater, or the like can be used in addition to the halogen heater.

The nip forming member 24 is adapted to slide directly on the inner surface of the belt. The shape of the nip portion N is determined by receiving the pressing force of the pressurizing roller 22. In the present embodiment, the shape of the nip portion N is flat, but it may be concave or other shape.

As shown in FIG. 3, the support member 25 supports the nip forming member 24 with a cut surface, so that the nip forming member 24 and the support member 25 are in line contact with each other, so that heat does not easily flow to the support member 25. Further, by providing the cut surface of the support member 25 with an arcuate convex shape, it is possible to impart the effect of canceling the bending of the stay when a load is applied and preventing the reduction of the central nip.

The reflection member 26 is fixedly supported by the support member 25 so as to face the halogen heater 23. By reflecting the heat (or light) radiated from the halogen heater 23 to the fixing belt 21 by the reflecting member 26, the heat is suppressed from being transferred to the support member 25 and the like, and the fixing belt 21 is efficiently heated. At the same time, we are trying to save energy. As the material of the reflective member 26, aluminum, stainless steel, or the like is used. In particular, when silver having a low emissivity (high reflectance) is vapor-deposited on an aluminum base material, the heating efficiency of the fixing belt 21 can be improved.

The shielding member 27 is formed by forming a metal plate having a thickness of 0.1 mm to 1.0 mm into an arc-shaped cross-sectional shape along the inner peripheral surface of the fixing belt 21. Further, the shielding member 27 can be moved in the circumferential direction of the fixing belt 21 as needed. In the present embodiment, in the circumferential region of the fixing belt 21, there is a direct heating region in which the halogen heater 23 directly faces the fixing belt 21 and heats the region, and between the halogen heater 23 and the fixing belt 21, other than the shielding member 27. There is a non-direct heating region in which members (reflection member 26, support member 25, nip forming member 24, etc.) intervene, but when heat shielding is required, the shielding member 27 is placed at a shielding position on the direct heating region side. Set up. On the other hand, when heat shielding is not necessary, the shielding member 27 can be moved to the retracted position on the non-direct heating region side, and the shielding member 27 can be retracted to the back side of the reflective member 26 and the support member 25. .. Further, since the shielding member 27 requires heat resistance, it is preferable to use a metal material such as aluminum, iron, stainless steel, or ceramic as the material.

FIG. 4 is a cross-sectional view showing a fixing device according to an embodiment of claim 1, and FIG. 5 is a perspective view of a nip forming member and a support member according to an embodiment of claim 1.

The fixing device 20 of this embodiment will be described with reference to FIGS. 4 and 5. The fixing device 20 in the present embodiment includes an endless fixing member 21, an opposing member 22 that abuts on the outer peripheral surface of the fixing member, a heating source 23 that heats the fixing member 21, and a portion facing from the inner peripheral side of the fixing member 21. A nip forming member 24 that abuts on 22 to form a nip portion N, a support member 25 that supports the nip forming member 24, and a nip forming member that is independently arranged between the nip forming member 24 and the support member 25. The difference from the conventional case is that the surface pressure distribution member 29 having a contact surface with the 24 larger than the area of the contact surface of the support member 25 is provided.

A contact surface with the nip forming member 24 is formed between the nip forming member 24 and the support member 25 formed of a thin metal plate material having both low heat capacity and heat equalization in order to suppress temperature unevenness in the axial direction during paper passing. By disposing the surface pressure distribution member 29 larger than the area of the contact surface of the support member 25, the surface pressure distribution member 29 nip the concentrated load from the support member 25 against the pressing of the opposing member. It can be transmitted as a load distributed over the entire contact surface with the forming member 24, and it is possible to prevent plastic deformation of the nip forming member 24.

By making the surface of the support member 25 that supports the nip forming member a cut surface such as the cut surface 25a that is easy to provide a highly accurate continuous convex shape, the center of the nip is bent by pressing from the opposing member. It is possible to prevent the plastic deformation of the nip forming member 24 by the surface pressure distribution member 29 while obtaining the effect of avoiding the narrowing of the portion. Further, by supporting by the plurality of cut surfaces 25a, it is possible to stably support the nip forming member 24 and the surface pressure distribution member 29.

Subsequently, the fixing device according to the embodiment of claims 4, 5, 6, and 8 will be described. The surface pressure distribution member 29 will be described with reference to FIGS. 6 and 7. In the conventional configuration shown in FIG. 6, the nip forming member 24 made of a metal material is supported by the support member 25 made of a steel plate or the like. Since the metal material of the nip forming member 24 is required to have high (large) thermal conductivity in order to improve heat soaking property, aluminum or copper having high thermal conductivity is used among the metals having excellent workability and production volume. Is desirable. However, since a concentrated load such as f1 and f2 is applied from the support member 25 to the nip forming member 24 on a limited contact surface, the nip forming member made of aluminum or copper is inferior in rigidity to the steel plate of the support member 25. There is a problem that 24 is plastically deformed.

In this embodiment shown in FIG. 7, the member and the shape (work-hardened shape and thick shape) have the same or higher rigidity than the nip forming member 24 made of aluminum or copper. By providing a surface pressure distribution member 29 whose contact surface with the nip forming member 24 is larger than the area of the cut surface of the support member 25 between the nip forming member 24 and the support member 25, the pressing F of the opposing member 22 is dealt with. Therefore, the concentrated loads f1 and f2 from the support member 25 can be transmitted to the nip forming member 24 as a load fa in which the surface pressure distribution member 29 disperses the loads f1 and f2 over the entire contact surface with the nip forming member 5. , It is possible to prevent the plastic deformation of the nip forming member 24. Further, the surface pressure dispersion member 29 is not only excellent in rigidity as compared with aluminum and copper, but also has a lower (smaller) thermal conductivity than aluminum, copper and steel plate, so that the heat from the nip forming member 24 is generated. It is also possible to prevent the movement of the material, so it is desirable to use a stainless steel material. Further, in the case of a surface pressure distribution member using a pressed part, it is preferable that the surface in contact with the support surface and the nip forming member is not a cut surface. This is because the cut surface of the press working is made rough, so that it is difficult to secure contact with the entire surface, and as a result, the pressure is concentrated on a part of the surface, and it is difficult to obtain the surface pressure dispersion effect.

By making the surface pressure distribution member 29 an independent component, the easily machined cut surface of the support member 25 can be used as it is, so that a highly accurate convex shape can be maintained. Further, it is possible to use an elastic member, a resin material, or the like, which is difficult to be identified with the support member 25, as a material. In addition, since the stress applied during the same processing as the support member 25 can be avoided, the heat transfer to the nip forming member 24 can be reduced by thinning the surface pressure dispersion member 29 to reduce the heat capacity. It will be possible. Further, as shown in FIG. 8, by providing the surface pressure distribution member 29 with the opening 80, the heat capacity can be reduced, so that the heat transfer of the nip forming member 24 can be reduced.

Subsequently, the fixing device according to the embodiment of claim 7 will be described. FIG. 9 is an example of a shape in which the surface pressure distribution member 29 can increase the rigidity as compared with the nip forming member 24. As shown in FIG. 9, by providing a plurality of uneven shapes 90 on the surface of the surface pressure dispersion member 29, the strength of the surface pressure dispersion member 29 can be increased and deformation of the surface pressure dispersion member 29 itself can be prevented.

Subsequently, the fixing device according to the embodiment of claims 9 and 10 will be described. FIG. 10 is an example of a support member 25 formed by a convex portion 1000 having an intermittent cut surface, and a plurality of surface pressure distribution members arranged according to the convex portion 1000. By forming the support member 25 into an intermittent convex shape as shown in FIG. 10 and partially arranging the surface pressure distribution member 29 accordingly, the contact area can be further reduced and the heat transfer of the nip forming member 24 is reduced. It becomes possible.

Subsequently, the fixing device according to the embodiment of claim 11 will be described. 11 and 12 are examples of a fixing device including a heat insulating member 30 having a low thermal conductivity between the nip forming member 24 and the surface pressure distribution member 29. As shown in the figure, not only the surface pressure reducing member 29 that prevents the nip forming member 24 from being deformed, but also a plurality of heat insulating members 30 having excellent thermal conductivity are combined to form the nip while reducing the heat transfer of the nip forming member 24. It is possible to prevent the member 24 from being deformed and to reinforce it. The material of the heat insulating member 30 may be, for example, the same material as the surface pressure dispersion member 29, or a material having a lower (smaller) thermal conductivity than aluminum, copper, or a steel plate.

Subsequently, a further example in which the convex shape is formed by changing the thickness of the surface pressure distribution member without forming the convex shape by the support member for facilitating processing will be described. FIG. 13 shows that the height of the cut surface 25a of the support member 25 shown in FIG. 10 is made uniform, and among the plurality of surface pressure distribution members 29 shown in FIG. 10, the surface pressure distribution member 29 is in the direction of the nip forming member 24. An example of configuration with different thickness is shown. In FIG. 13, a member 291 arranged on the end side in the width direction and a member 292 arranged in the center portion in the width direction are provided, and the member 292 is arranged so as to be thicker than the member 291. When the surface pressure distribution member 29 is arranged, the central portion as a whole is thicker than the end portion.

With such a configuration, the nip-forming member support surfaces 25a of the support member are formed at substantially the same height, so that the shearing process becomes easy, and further, the two stays (each plate of the support member 25) By aligning the support surface with the same reference surface (flat practical datum shape) and integrating (adhesion, welding, etc.), it is possible to make a support member in which the heights of the two stays are aligned with high accuracy. By sandwiching surface pressure reducing members having different thicknesses between the support member 25 having the same height support surface and the nip forming member 24, a highly accurate central convex shape can be created. At this time, in order to obtain a sufficient convex shape, it is desirable to use at least a member having a higher rigidity than the pressure roller as the nip forming member.

Further, as another embodiment, FIG. 14 shows a method of creating a highly accurate central convex shape while sandwiching a surface pressure reducing member having the same thickness between a support member having a support surface having the same height and a nip forming member. .. In FIG. 14, the plurality of surface pressure distribution members 291 and 292 shown in FIG. 13 have the same thickness, and the member 294 arranged on the end side in the width direction is a member arranged in the center portion in the width direction. It is composed of members having a lower rigidity than the 295 (the member 295 has a higher rigidity than the member 294).

In this way, the heights of the support surfaces are all the same, and the thickness of the surface pressure distribution member is also the same. Sometimes the central part can create a convex shape. By doing so, the surface on which the nip forming member is placed becomes flat during product assembly (non-pressurization), so that there is an advantage that stable assembly can be performed. Further, by using the embodiments of FIGS. 13 and 14 together, it is possible to meet a wide range of requirements for more appropriate product functions and product assemblability. Although FIGS. 13 and 14 are views of the intermittent support surface, it does not necessarily have to be intermittent, and may have a shape like the cut surface 25a shown in FIG. 5, for example.
<Modification example>

The nip forming member 24 may be provided with a heat generating portion on one surface thereof. 15 and 16 show examples of a nip forming member provided with a heat generating portion. FIG. 15 is a cross-sectional view showing an outline of a fixing device in which a heat generating portion is provided on the nip forming member 24. FIG. 16 is a diagram showing a configuration example of the heat generating portion shown in FIG. As shown in FIGS. 15 and 16, a heating mechanism unit 1500 having a heating element 1501 and a circuit 1502 for generating heat of the heating element 1501 is provided inside the nip forming member 24. The configuration includes, for example, as shown in FIG. 7, a nip forming member 24, a surface pressure distribution member 29, and a support member 25 supported by a plurality of cut surfaces 25a in the longitudinal direction via the surface pressure distribution member 29. It can be used for a fixing device provided with.
As described above, the load concentration can be improved by providing the surface pressure distribution member between the nip forming member and the support member. In addition, while maintaining the convex shape of the support member having the conventional configuration and reducing heat transfer from the nip forming member to other parts, plastic deformation of the nip forming member is prevented to form a nip portion suitable for image formation. Is possible.

1 Image forming device 20 Fixing device 21 Fixing member 22 Opposing member 23 Heating source 24 Nip forming member 25 Support member 29 Surface pressure distribution member 25a Cut surface 80 Opening 90 Concavo-convex shape 30 Insulation member 291, 292, 294, 295 Member 1500 Heat generation Mechanism part 1501 Heating element 1502 Circuit

JP-A-2019-159176

Claims (13)

Rotatable endless fixing member and
An opposing member that comes into contact with the outer peripheral surface of the fixing member,
A heating element for heating the fixing member and
A nip forming member made of a metal material and a nip forming member made of a metal material are formed by contacting the facing member from the inner peripheral side of the fixing member to form a nip portion.
A support member that supports the nip forming member via a surface pressure distribution member, and
A surface pressure distribution member disposed between the nip forming member and the support member is provided.
The area of the contact surface between the surface pressure dispersion member and the nip forming member is larger than the area of the contact surface between the surface pressure dispersion member and the support member.
A fixing device characterized in that. Rotatable endless fixing member and
An opposing member that comes into contact with the outer peripheral surface of the fixing member,
A heating element for heating the fixing member and
A nip forming member made of a metal material and a nip forming member made of a metal material are formed by contacting the facing member from the inner peripheral side of the fixing member to form a nip portion.
A support member that supports the nip forming member on a cut surface via the surface pressure distribution member, and
A surface pressure distribution member disposed between the nip forming member and the support member is provided.
The area of the contact surface between the surface pressure dispersion member and the nip forming member is larger than the area of the cut surface where the surface pressure dispersion member and the support member are in contact with each other.
A fixing device characterized in that. Rotatable endless fixing member and
An opposing member that comes into contact with the outer peripheral surface of the fixing member,
A heating element for heating the fixing member and
A nip forming member made of a metal material and a nip forming member made of a metal material are formed by contacting the facing member from the inner peripheral side of the fixing member to form a nip portion.
A support member that supports the nip forming member with a plurality of cut surfaces in the longitudinal direction via the surface pressure distribution member, and
A surface pressure distribution member disposed between the nip forming member and the support member is provided.
The area of the contact surface between the surface pressure dispersion member and the nip forming member is larger than the total area of the cut surfaces in contact between the surface pressure dispersion member and the support member.
A fixing device characterized in that. The metal material of the nip forming member is aluminum.
The fixing device according to any one of claims 1 to 3, wherein the fixing device is characterized by the above. The metal material of the nip forming member is copper.
The fixing device according to any one of claims 1 to 3, wherein the fixing device is characterized by the above. The surface pressure distribution member is made of a material having higher rigidity than the nip forming member.
The fixing device according to any one of claims 1 to 5, characterized in that. The surface pressure distribution member has a shape having higher rigidity than the nip forming member.
The fixing device according to any one of claims 1 to 6, wherein the fixing device is characterized by the above. The surface pressure dispersion member is made of a material having a low thermal conductivity with respect to the nip forming member.
The fixing device according to any one of claims 1 to 7, wherein the fixing device is characterized by the above. The cut surface of the support member is composed of intermittent convex portions.
The fixing device according to any one of claims 1 to 8, wherein the fixing device is characterized by the above. It is composed of a plurality of surface pressure distribution members corresponding to a plurality of cut surfaces or intermittent convex portions of the support member.
The fixing device according to claim 3 or 9. A heat insulating member having a small thermal conductivity is provided between the nip forming member and the surface pressure dispersion member.
The fixing device according to any one of claims 1 to 10, wherein the fixing device is characterized by the above. The fixing device according to any one of claims 1 to 11.
An image forming apparatus characterized in that. Rotatable endless fixing member and
An opposing member that comes into contact with the outer peripheral surface of the fixing member,
A heating element for heating the fixing member and
A nip forming member having a heating element that abuts on the facing member from the inner peripheral side of the fixing member to form a nip portion, and a nip forming member.
A support member that supports the nip forming member with a plurality of cut surfaces via a surface pressure distribution member, and
A surface pressure distribution member disposed between the nip forming member and the support member is provided.
The area of the contact surface between the surface pressure dispersion member and the nip forming member is larger than the area of the contact surface between the surface pressure dispersion member and the support member.
A fixing device characterized in that.

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