JP7448876B2 - Heating device, image forming device - Google Patents

Description

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

As a heating device, there is a fixing device provided in an image forming apparatus such as a printer. The fixing device includes a fixing belt as a rotating member, and is provided inside the fixing belt with a heating member that heats the fixing belt and a nip forming member that forms a fixing nip between the fixing belt and the pressure roller.

2. Description of the Related Art There is a fixing device in which a nip forming member including a metal member made of a sheet metal material slides directly onto a fixing belt without using a sliding sheet or the like. If such a metal member is formed into a flat plate shape, the edge of the end portion in the paper conveyance direction may slide on the fixing belt, causing wear and damage to the fixing belt. Furthermore, even when a sliding sheet is used, the sliding sheet may slide against the edge of the metal member, causing wear or damage to the sliding sheet.

As a countermeasure against the above problem, there is a metal heat equalizing member having a configuration in which both ends of the sheet conveyance direction are bent in a direction intersecting the sheet conveyance direction (for example, Patent Document 1). With this configuration, the fixing belt slides on the curved surface portion of the heat equalizing member on both sides in the paper conveyance direction, so that wear and damage to the fixing belt can be prevented.

There was a problem in that the metal member had high rigidity and had no flexibility in its shape.

In order to solve the above problems, the present invention provides a rotating member, an opposing member that faces the rotating member, and a nip that is provided inside the rotating member and is provided between the rotating member and the opposing member via the rotating member. A heating device including a nip forming member that forms a portion of the rotating member, and a heating member that heats the rotating member, the nip forming member having a metal member, and the metal member extending in the direction of conveying the object to be heated. an extending nip forming section; and a longitudinal section of the nip forming member provided on at least one of the upstream side and downstream side of the nip forming section in the direction of conveyance of the object to be heated, and in the direction intersecting the direction of conveyance of the object to be heated. and a bent portion bent in a direction different from the bent portion, and the metal member includes a reduced stiffness portion in the bent portion , and the reduced stiffness portion is bent in a direction intersecting the longitudinal direction and the thickness direction of the bent portion. It is characterized by a slit that is open on one end side .

The rigidity of the metal member can be lowered.

1 is a schematic configuration diagram of an image forming apparatus. 1 is a schematic configuration diagram of a fixing device according to an embodiment of the present invention. It is a perspective view of a stay. FIG. 3 is a plan view of the fixing device. It is a perspective view of a stay and a nip formation member. It is a figure which shows the positional relationship of the longitudinal direction of the slit of a bending part, and the support surface of a stay. FIG. 7 is a perspective view showing different forms of the stiffness reducing portion. FIG. 7 is a perspective view showing different forms of the stiffness reducing portion. FIG. 7 is a perspective view showing different forms of the stiffness reducing portion. FIG. 3 is a diagram showing a nip forming member having a sliding sheet. FIG. 3 is a schematic configuration diagram of a different fixing device.

Embodiments according to the present invention will be described below with reference to the drawings. In each figure, the same or corresponding parts are denoted by the same reference numerals, and repeated explanations thereof will be simplified or omitted as appropriate. Hereinafter, in each embodiment, a fixing device that fixes toner using heat will be described as an example of a heating device.

At the center of the color image forming apparatus 1 shown in FIG. 1, an image forming section 2 in which four process units 9Y, 9M, 9C, and 9K are removably provided is arranged. Each of the process units 9Y, 9M, 9C, and 9K accommodates developers of different colors, yellow (Y), magenta (M), cyan (C), and black (K), corresponding to the color separation components of a color image. The configuration is the same except for the

Specifically, each process unit 9 includes a photoreceptor drum 10, which is a drum-shaped rotating body capable of carrying toner as a developer on its surface, and a charging roller 11 that uniformly charges the surface of the photoreceptor drum 10. and a developing device 12 having a developing roller that supplies toner to the surface of the photoreceptor drum 10.

An exposure section 3 is arranged below the process unit 9. The exposure section 3 is configured to emit laser light based on image data.

A transfer section 4 is arranged above the image forming section 2 . The transfer unit 4 includes an endless intermediate transfer belt 16 stretched around a drive roller 14 and a driven roller 15 so as to be able to run around it, and an endless intermediate transfer belt 16 that faces the photoreceptor drums 10 of each process unit 9 with the intermediate transfer belt 16 interposed therebetween. It is composed of a primary transfer roller 13 and the like arranged at a certain position. Each primary transfer roller 13 presses the inner peripheral surface of the intermediate transfer belt 16 at its respective position, and a primary transfer nip is formed at the location where the pressed portion of the intermediate transfer belt 16 and each photoreceptor drum 10 come into contact. has been done.

Further, a secondary transfer roller 17 is disposed at a position facing the drive roller 14 with the intermediate transfer belt 16 interposed therebetween. The secondary transfer roller 17 presses the outer peripheral surface of the intermediate transfer belt 16, and a secondary transfer nip is formed where the secondary transfer roller 17 and the intermediate transfer belt 16 come into contact. The drive roller 14, intermediate transfer belt 16, and secondary transfer roller 17 function as an image transfer section that transfers an image onto paper.

The paper feed unit 5 is located at the lower part of the image forming apparatus 1 and includes a paper feed cassette 18 that accommodates paper P as a recording medium or a heated object, and a paper feed roller that carries out the paper P from the paper feed cassette 18. It consists of 19 mag.

The conveyance path 7 is a conveyance path for conveying the paper P carried out from the paper feed section 5, and in addition to the pair of registration rollers 20, a pair of conveyance rollers are used in the middle of the conveyance path 7 to reach the paper discharge section 8, which will be described later. are placed appropriately.

The fixing device 6 includes a fixing belt 31 that is heated by a heating member, a pressure roller 32 that can press the fixing belt 31, and the like.

The paper discharge section 8 is provided at the most downstream position of the conveyance path 7 of the image forming apparatus 1 . The paper ejection section 8 is provided with a pair of paper ejection rollers 21 for ejecting the paper P to the outside, and a paper ejection tray 22 for stocking the ejected paper P.

At the top of the image forming apparatus 1, toner bottles 23Y, M, C, and K filled with yellow, cyan, magenta, and black toners are removably provided. The toner of each color is supplied to the developing device 12 of each color via a supply path provided between the toner bottles 23Y, M, C, and K to each developing device 12.

The basic operation of the image forming apparatus 1 will be described below with reference to FIG.

In the image forming apparatus 1, when an image forming operation is started, an electrostatic latent image is formed on the surface of the photosensitive drum 10 of each process unit 9Y, 9M, 9C, and 9K. The image information exposed onto each photoreceptor drum 10 by the exposure unit 3 is monochrome image information obtained by separating a desired full-color image into yellow, cyan, magenta, and black color information. An electrostatic latent image is formed on each photoreceptor drum 10, and the toner stored in each developing device 12 is supplied to the photoreceptor drum 10 by a drum-shaped developing roller, so that the electrostatic latent image is formed on the photoreceptor drum 10. It is visualized as a toner image (developer image).

In the transfer section 4, the intermediate transfer belt 16 is driven to run in the direction of arrow A in the figure by the rotation of the drive roller 14. Furthermore, a constant voltage or constant current controlled voltage having a polarity opposite to the charged polarity of the toner is applied to each primary transfer roller 13 . As a result, a transfer electric field is formed in the primary transfer nip, and the toner images formed on each photoreceptor drum 10 are sequentially transferred onto the intermediate transfer belt 16 in the primary transfer nip in an overlapping manner.

On the other hand, when the image forming operation is started, the paper feed roller 19 of the paper feed section 5 is rotated in the lower part of the image forming apparatus 1, so that the paper P stored in the paper feed cassette 18 is transferred to the conveyance path 7. Sent out. The paper P sent out to the conveyance path 7 is timed by the registration rollers 20 and sent to the secondary transfer nip between the secondary transfer roller 17 and the drive roller 14. At this time, a transfer voltage having a polarity opposite to the toner charge polarity of the toner image on the intermediate transfer belt 16 is applied, and a transfer electric field is formed in the secondary transfer nip. The toner images on the intermediate transfer belt 16 are transferred onto the paper P all at once by the transfer electric field formed in the secondary transfer nip.

The paper P on which the toner image has been transferred is conveyed to the fixing device 6, and the paper P is heated and pressurized by the fixing belt 31 and the pressure roller 32, so that the toner image is fixed on the paper P. Then, the paper P on which the toner image has been fixed is separated from the fixing belt 31, is transported by a pair of transport rollers, and is ejected to a paper ejection tray 22 by a paper ejection roller 21 in a paper ejection section 8.

The above explanation is about the image forming operation when forming a full color image on paper P, but when forming a monochrome image using any one of the four process units 9Y, 9M, 9C, 9K, It is also possible to use two or three process units 9 to form two- or three-color images.

Next, a more detailed configuration of the fixing device 6 will be described using FIG. 2.

As shown in FIG. 2, the fixing device 6 includes a fixing belt 31 as a fixing member or a rotating member, a pressure roller 32 as a pressure member or an opposing member, a nip forming member 50, and a heater 40 as a heating member. , a stay 35 as a support member, a holder 36 as a fixing member holding member, a side plate 37, and the like. The nip forming member 50, the heater 40, and the stay 35 are provided on the inner peripheral surface side of the fixing belt 31. The nip forming member 50, the heater 40, and the stay 35 are arranged in the longitudinal direction of the fixing belt 31 (the direction perpendicular to the plane of the drawing, see the double arrow D direction in FIG. 4), in the axial direction of the pressure roller 32, or , which is also the width direction of the paper passed through the fixing device). Hereinafter, this direction will also simply be referred to as the longitudinal direction. Further, the vertical direction in FIG. 2 is the lateral direction of the nip forming member 50 (or metal member 33), and is also the paper conveyance direction (see arrow C1 in FIG. 2).

As shown in FIG. 2, the fixing belt 31 is composed of a thin and flexible endless belt member (including a film). Specifically, the fixing belt 31 includes an inner base material made of a metal material such as nickel or SUS, or a resin material such as polyimide (PI). Furthermore, it is constituted by a release layer on the outer peripheral side formed of tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer (PFA), polytetrafluoroethylene (PTFE), or the like. Furthermore, 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.

The pressure roller 32 includes a core metal, an elastic layer made of foamable silicone rubber, silicone rubber, fluororubber, etc. provided on the surface of the core metal, and a separation layer made of PFA, PTFE, etc. provided on the surface of the elastic layer. It is composed of mold layers. The pressure roller 32 is urged toward the fixing belt 31 by the urging means, and is brought into contact with the nip forming member 50 (metal member 33) via the fixing belt 31. At a location where the pressure roller 32 and the fixing belt 31 come into pressure contact, the elastic layer of the pressure roller 32 is crushed, thereby forming a nip portion N with a predetermined width. The nip portion N is formed continuously in the longitudinal direction.

Further, the pressure roller 32 is configured to be rotated in the direction of arrow B1 by a drive source such as a motor provided in the main body of the image forming apparatus. When the pressure roller 32 is driven to rotate, the driving force is transmitted to the fixing belt 31 at the nip portion N, and the fixing belt 31 is driven to rotate in the direction of arrow B2.

In this embodiment, the nip forming member 50 is composed only of the metal member 33 made of a metal material. However, as in the embodiment described later, the nip forming member 50 may include a resin base pad (resin member) and a metal member.

The metal member 33 is preferably made of a material with high thermal conductivity, such as gold, silver, copper, or graphite, in order to equalize the temperature distribution in the longitudinal direction of the fixing belt 31. Further, the surface of the metal member 33 that contacts the fixing belt 31 is coated with a sliding agent such as grease in order to reduce the sliding resistance with the fixing belt 31.

The metal member 33 has a nip forming portion 33a and a bent portion 33b. The metal member 33 can be formed, for example, by bending and forming a sheet metal material.

The nip forming portion 33a is a portion that comes into contact with the fixing belt 31 from its inner peripheral surface side and forms the above-mentioned nip portion N between it and the pressure roller 32. The nip forming portion 33a extends in the paper conveyance direction (vertical direction in the figure). However, in this embodiment, the downstream portion of the nip forming portion 33a is not limited to the direction parallel to the paper conveyance direction, but extends in a direction tilted with respect to the paper conveyance direction.

The nip forming portion 33a contacts a portion of the fixing belt 31 that faces the pressure roller 32 from its inner peripheral surface side. Due to this contact, the metal member 33 forms the aforementioned nip portion N with the pressure roller 32 via the fixing belt 31.

Bent portions 33b are provided at the upstream and downstream ends of the nip forming portion 33a in the sheet conveyance direction. That is, the metal member 33 has bent portions 33b bent toward the left in the figure in a direction intersecting the paper transport direction at the upstream and downstream ends of the metal member 33 in the paper transport direction. In other words, the metal member 33 has a bent portion 33b bent in a direction away from the pressure roller 32. The bent portion 33b is provided over most of the length of the metal member 33.

The bent portion 33b consists of a curved surface portion 33c and a tip portion 33d. The curved surface portion 33c is a portion that has a curved shape and changes the direction in which the metal member 33 extends. The tip portion 33d is a portion provided closer to the end of the metal member 33 than the curved surface portion 33c, and extends in the left-right direction in the figure.

Unlike the configuration of this embodiment, when the metal member 33 is formed into a flat plate shape, that is, when the bent portion 33b is not provided on the upstream and downstream sides of the metal member 33 in the sheet conveyance direction, the sheet conveyance of the metal member 33 is There is a risk that the fixing belt 31 may come into sliding contact with the edge portion in the direction (vertical direction in the figure) and the fixing belt 31 may be worn out or damaged. In contrast, by forming the curved portions 33c on the upstream and downstream sides of the metal member 33 in the paper conveyance direction as in the present embodiment, the metal member 33 can be attached to the fixing belt by the curved portions 33c at both ends in the paper conveyance direction. 31 and slide. Therefore, the frictional force generated between the fixing belt 31 and the metal member 33 can be reduced, and wear or damage to the fixing belt 31 can be prevented.

The heater 40 of this embodiment is a halogen heater. The heater 40 is a heating member that heats the fixing belt 31 from the inner peripheral side using radiant heat by emitting infrared light. Further, the heater 40 may be an IH coil, a resistance heating element, a carbon heater, or the like.

The stay 35 supports the metal member 33 from its back side. More specifically, the stay 35 abuts the support surface 35a against the metal member 33 from the side opposite to the pressing direction of the pressure roller 32 (left side in the figure) over its longitudinal direction. As a result, bending of the metal member 33 due to the pressure applied by the pressure roller 32 is suppressed in its longitudinal direction, and a flatter nip portion N is formed between the fixing belt 31 and the pressure roller 32. In particular, since the stay 35 extends in the pressing direction (horizontal direction in the figure), it has a horizontally elongated cross section extending in the pressing direction, and the section modulus increases, resulting in the pressing force of the pressing roller 32. It is possible to effectively suppress the deflection of the metal member 33 against this.

In order to satisfy the function of preventing the metal member 33 from bending, the stay 35 is desirably made of a metal material with high mechanical strength, such as stainless steel or iron. At this time, it is desirable that each plate material of the stay 35 is created by punching a steel plate. By making the stay 35 from a steel plate, the stay 35 can be made at low cost and having high rigidity.

The holders 36 are provided at both ends of the fixing belt 31 in the longitudinal direction, and support the fixing belt 31 from its inner peripheral surface. The holder 36 contacts the inner circumferential surface of the fixing belt 31 in the circumferential direction of the fixing belt 31 at a position where the fixing belt 31 faces the metal member 33 and at a position other than the vicinity thereof. Since the holder 36 supports the fixing belt 31 from its inner peripheral surface side, the fixing belt 31 can maintain its cylindrical shape.

The side plates 37 are provided at both longitudinal ends of the fixing device 6 and hold the stay 35 and the holder 36. The stay 35 is supported by the side plate 37 by fitting the supported surface 35b into a hole 37a formed in the side plate 37. The side plate 37 is fixed to the housing of the fixing device 6.

Further, a reflecting plate that reflects radiant heat from the heater 40 is arranged between the heater 40 and the stay 35. The reflector is fixed to the stay 35. Further, a temperature sensor serving as a temperature detection means for detecting the temperature of the fixing belt 31 is provided opposite the fixing belt 31 .

Next, a more detailed configuration of the stay 35 will be described using FIG. 3.

As shown in FIG. 3, the stay 35 is composed of an upper stay 351, a lower stay 352, and a right stay 353. The upper stay 351 and the lower stay 352 are formed of a sheet metal material. The lower end surfaces of the upper stay 351 and the lower stay 352 in FIG. 3 are formed as linear sheared surfaces whose height is uniform in the longitudinal direction. The upper stay 351 and the lower stay 352 have protrusions provided intermittently in the longitudinal direction on their upper end surfaces. This protrusion passes through the right stay 353 in the vertical direction in the figure, and the upper end surface of the protrusion forms a support surface 35a that is one shear surface. As shown in FIG. 4, the amount of protrusion of the support surface 35a gradually increases from both ends in the longitudinal direction toward the center. In other words, the support surface 35a forms a convex shape extending from both ends toward the center. Note that in FIG. 4, members such as the fixing belt 31 are omitted, and the stay 35, the metal member 33, and surrounding members are mainly illustrated.

As shown in FIG. 3, the upper end surface of the lower stay 352 in FIG. There is. That is, longitudinal rows (support rows) of the support surfaces 35a formed by the upper stay 351 and the lower stay 352 are provided at a predetermined distance apart in the paper conveyance direction (vertical direction in FIG. 2).

The upper stay 351 and the lower stay 352 are fixed by welding, adhesion, caulking, screwing, or the like. Further, each of the stays 351 and 352 is fixed to the right stay 353 by welding, adhesion, caulking, screwing, or the like. The lower end surface of each stay 351, 352 constitutes a supported surface 35b which is the other sheared surface.

The support surface 35a, which is a sheared surface formed on the stay 35 made of sheet metal, can easily achieve dimensional accuracy. Therefore, by supporting the metal member 33 by the support surface 35a, the metal member 33 can be positioned with high precision. As a result, it is possible to provide a fixing device that can improve component reliability and reduce inspection costs.

By the way, as shown in FIG. 4, the stay 35 has a structure of a double-supported beam supported by the side plates 37 at both ends thereof in the longitudinal direction, so that it tends to bend at the center side in the longitudinal direction. Due to such deflection, the fixing belt 31 and the pressure roller 32 cannot be brought into sufficient pressure contact at the center in the longitudinal direction, and the nip width (width in the width direction of the nip portion N) becomes small at the center in the longitudinal direction. There is a risk that this may occur. If the nip width becomes non-uniform in the longitudinal direction, the amount of heat given to the toner on the paper passing through the nip portion N will be too much or too little, resulting in poor fixing.

However, in the present embodiment, as described above, the amount of protrusion of the support surface 35a from the right stay 353 increases as it goes from both longitudinal ends toward the center, so that the nip caused by the deflection of the stay 35 increases. By canceling out the deviation, it is possible to obtain a nip portion N having a uniform nip width.

Further, by providing the support surface 35a of the stay 35 intermittently in the longitudinal direction, the contact area of the stay 35 with the metal member 33 can be reduced. Thereby, the amount of heat transferred from the metal member 33 to the stay 35 is reduced, and the fixing device 6 can efficiently heat the fixing belt 31. In other words, it is possible to save energy and increase the speed of the fixing device 6.

Furthermore, by providing each support surface 35a intermittently, the shape of each support surface 35a can be individually set or finely adjusted, so that the reliability of the component can be easily improved.

By the way, by providing the bent portions 33b on both sides of the metal member 33 in the paper conveyance direction, the rigidity of the metal member 33 in the longitudinal direction (rigidity against deformation in a direction intersecting the longitudinal direction) is increased. This makes it difficult for the metal member 33 to follow the convex shape (see FIG. 4) formed toward the center of the support surface 35a of the stay 35 described above. If the metal member 33 does not sufficiently follow the support surface 35a, the nip width of the nip portion N will become uneven. In addition, the metal member 33 may be twisted in the longitudinal direction, and the frictional force between it and the fixing belt 31 may locally increase, causing uneven wear, or the nip pressure on the paper passing through the nip portion N may locally increase. There was a problem in that the paper became large and caused transportation defects such as paper wrinkles.

The configuration of this embodiment for solving the above problem, specifically, the stiffness reducing portion provided in the metal member 33 will be explained using FIG. 5. FIG. 5 is a perspective view showing the pressure roller 32 and the metal member 33 extracted.

As shown in FIG. 5, each bent portion 33b provided on both sides of the metal member 33 in the paper conveyance direction is provided with a slit 33b1 as a stiffness reducing portion midway in the longitudinal direction.

The slit 33b1 is a cutout portion provided in the tip 33d and opened on the end side of the tip 33d (the left side in the figure in a direction different from the longitudinal direction of the metal member 33). The slits 33b1 are provided at multiple locations in the longitudinal direction. However, it may be placed in one place. Note that among the slits 33b1 shown in FIG. 5, the slit 33b1 at the upper left in the figure is formed at approximately the center position of the metal member 33 in the longitudinal direction.

By providing the slit 33b1 midway in the longitudinal direction of the tip portion 33d, the bending rigidity of the metal member 33, especially the bending rigidity in the longitudinal direction, is reduced, and the metal member 33 can easily follow the convex shape of the stay 35. Therefore, it is possible to prevent the nip width of the nip portion N from becoming non-uniform, and the above-mentioned fixing failure can be prevented. Further, the metal member 33 can be prevented from being twisted in the longitudinal direction.

Furthermore, as shown in FIG. 5, it is preferable that the slits 33b1 provided in the upstream and downstream bent portions 33b in the paper conveyance direction be arranged at the same position in the longitudinal direction. Thereby, in the bent portion 33b, the positions with low rigidity in the longitudinal direction can be aligned, so that the metal member 33 can more easily follow the shape of the stay 35.

As shown in FIG. 6A, the slit 33b1 can be arranged at a position facing the support surface 35a of the stay 35 in the longitudinal direction (direction of double arrow D). This makes it possible to reduce the rigidity of the metal member 33 in the longitudinal direction at the position where the stay 35 abuts the metal member 33, making it easier for the metal member 33 to follow the convex shape of the stay 35. . Further, as shown in FIG. 6(b), the slit 33b1 can be arranged at a different position from the support surface 35a in the longitudinal direction. The slit 33b1 (or each reduced-rigidity portion described later) is a portion of the metal member 33 where the heat capacity is partially reduced. , it is possible to prevent the amount of heat around the slit 33b1 from becoming too small. Therefore, the temperature of the metal member 33 can be made more uniform in the longitudinal direction, and the temperature of the fixing belt 31 can be made more uniform in the longitudinal direction. However, one slit 33b1 can be placed at the same position as the support surface 35a, and another slit 33b1 can be placed at a different position from the support surface 35a, giving priority to either rigidity or heat uniformity at each position in the longitudinal direction. It can be selected as appropriate depending on the purpose.

In the above-mentioned metal member 33, the case where the slit 33b1 is provided at the tip 33d of the bent portion 33b is shown, but as shown in FIG. may be provided. This makes it possible to further reduce the rigidity of the metal member 33 and make it easier for the metal member 33 to follow the convex shape of the stay 35.

In this embodiment, it is preferable that the slit 33b1 has a longitudinal width of 2 mm or less. In other words, when the slit 33b1 is provided across the curved surface portion 33c and the nip forming portion 33a, a partial opening is provided on the side of the nip forming portion 33a that contacts the fixing belt 31, or in the vicinity thereof. Therefore, if the width of the slit 33b1 is too large, there is a possibility that the fixing belt 31 may enter the slit 33b1. Such a problem can be prevented by setting the width of the slit 33b1 to 2 mm or less.

The slit 33b1 of this embodiment is formed by press working, for example. When the slit 33b1 is provided across the curved surface portion 33c and the nip forming portion 33a as described above, the surface of the metal member 33 facing the fixing belt 31 is the side where the sagging portion is provided by press working, and the opposite side is Preferably, the side surface is the side on which the burr is provided. In other words, it is preferable that the side of the metal member 33 facing the fixing belt 31 be the upstream side in the shearing direction during press working. Even if the fixing belt 31 were to enter the portion of the nip forming portion 33a where the slit 33b1 was formed, by setting the side facing the fixing belt 31 as the side where the sagging portion is formed as described above, the metal member It is possible to prevent the fixing belt 31 from being worn out or damaged by the burrs formed on the fixing belt 33.

In the above description, the case where the stiffness reducing portion provided in the metal member 33 is in the shape of a slit has been described, but the shape is not limited to this.

For example, as shown in FIG. 8, a hole 33b2 may be provided in the metal member 33 as a stiffness reducing portion. The hole 33b2 passes through the metal member 33 in the thickness direction, and does not open toward the edge of the tip 33d. In this embodiment, the hole 33b2 is provided across the tip 33d, the curved surface 33c, and the nip forming portion 33a. However, the nip forming portion 33a that easily contributes to fixing quality may not be cut out, and the hole portion 33b2 may be provided from the tip portion 33d to the curved surface portion 33c, or may be provided only in the curved surface portion 33c.

Further, as shown in FIG. 9, the metal member 33 may be provided with a thin wall portion 33b3 as a stiffness reducing portion. In this embodiment, the thin portion 33b3 is provided from the edge of the upstream tip portion 33d to the edge of the downstream tip portion 33d, but only a portion thereof may be made thinner. In this case, it is more preferable to provide the thin wall portion 33b3 on the bent portion 33b because the rigidity can be effectively reduced. In addition, since the nip forming portion 33a is in contact with the fixing belt 31, from the viewpoint of heat uniformity etc., when only a portion of the metal member 33 in the widthwise direction is made thinner, the bent portion 33b has a thinner portion 33b3. It is better to set Thereby, it is possible to prevent the thermal conductivity of the metal member 33 from being impaired as much as possible.

These reduced-rigidity portions can reduce the rigidity of the bent portion 33b of the metal member 33, particularly in the longitudinal direction, and make it easier for the metal member 33 to follow the convex shape of the stay 35. Therefore, it is possible to prevent the nip width of the nip portion N from becoming nonuniform and to prevent the metal member 33 from being twisted in the longitudinal direction.

Next, a fixing device in which the nip forming member 50 includes a metal member and a resin member will be described.

For example, as shown in FIG. 10A, in this embodiment, the nip forming member 50 includes a metal member 33 and a resin base pad 34 (resin member 34). Further, a sliding sheet 41 is provided between the nip forming member 50 and the fixing belt 31. Moreover, the metal member 33 of this embodiment also has the nip formation part 33a and the bending part 33b like the above-mentioned embodiment.

The base pad 34 is provided on the opposite side of the nip portion N (left side in the figure) with respect to the metal member 33. The contact surface 34a of the base pad 34 that contacts the stay 35 is formed in a convex shape toward the center in the longitudinal direction, like the support surface 35a of the stay 35 in the above-described embodiment (see FIG. 4). Thereby, the deviation of the nip due to the deflection of the stay 35 can be offset, and the nip portion N having a uniform nip width can be obtained.

The sliding sheet 41 can be formed, for example, by impregnating a PTFE thread with a lubricant such as silicone oil. The sliding sheet 41 is provided from one end of the base pad 34 in the paper conveyance direction (vertical direction in the figure) to the other end, and covers the base pad 34 or the surface of the metal member 33 that faces the fixing belt 31 . By providing the sliding sheet 41, the slidability between the metal member 33 and the fixing belt 31 can be improved, and wear of the fixing belt 31 can be suppressed.

Alternatively, as shown in FIG. 10(b) or FIG. 10(c), the metal member 33 may be provided halfway from the upstream end of the nip forming member 50 in the paper conveyance direction to the downstream side. . That is, in this embodiment, the metal member 33 is not disposed downstream of the nip forming member 50 in the paper conveyance direction, and the base pad 34 contacts the fixing belt 31 via the sliding sheet 41 on the downstream side of the paper conveyance direction. A nip portion N is formed between the fixing belt 31 and the pressure roller 32. In this embodiment, the downstream portion of the base pad 34 in the paper conveyance direction is convex toward the pressure roller 32 (to the right in the figure). By configuring the metal member 33 not to face the convex portion of the base pad 34, processing of the metal member 33 can be facilitated.

In the case of the configuration in which the sliding sheet 41 is provided, since the metal member 33 does not come into direct contact with the fixing belt 31, a bent portion is formed in the downstream portion of the nip forming portion 33a in the paper conveyance direction, as shown in FIG. 10(b). It is possible to have a configuration in which no part is formed. However, even in this case, the above-described reduced rigidity portion can be formed in the bent portion 33b of the metal member 33 on the upstream side in the sheet conveyance direction. Note that the rotation of the fixing belt 31 generates a force on the metal member 33 from the upstream side in the paper conveyance direction to the downstream side. It is possible to prevent the member 33 from shifting relative to the base pad 34, and to reduce the frictional force generated between the metal member 33 and the sliding sheet 41 in the upstream portion. However, as shown in FIG. 10(c), a bent portion 33b may be formed on the downstream side of the metal member 33 in the sheet conveyance direction, and the tip portion 33d may extend in a direction intersecting the sheet conveyance direction. In this case, a reduced rigidity portion can be formed in the bent portion 33b on the upstream side and the downstream side in the paper conveyance direction. These reduced-rigidity parts can reduce the rigidity of the metal member 33 in the longitudinal direction in particular, making it easier for the metal member 33 to follow the convex shape of the base pad 34. Note that the stiffness-reduced portion is not limited to a slit, but may be a hole or a thin wall portion.

Further, the fixing device to which the present invention is applied is not limited to the above fixing device. For example, the present invention can also be applied to a fixing device shown in FIG. 11 below.

As shown in FIG. 11, the fixing device 6 of this embodiment includes a fixing belt 31, a pressure roller 32, a nip forming member 50, a heater 40, a stay 35, and a holder 36, as in the previous embodiment. and side plates etc. The fixing device 6 also includes a reflective member 38, a temperature sensor 29 that is opposed to the outer peripheral surface of the fixing belt 31 and serves as a temperature detection means for detecting the temperature of the fixing belt 31, a separation member 42 that separates the paper from the fixing belt 31, and the like. have The nip forming member 50 includes a metal member 33 and a base pad 34. Further, a sliding sheet 41 is provided between the nip forming member 50 and the fixing belt 31.

The base pad 34 is made of a somewhat hard material to ensure strength and is made of a heat-resistant material with a heat-resistant temperature of 200° C. or higher. Examples of materials for the base pad 34 include polyether sulfone (PES), polyphenylene sulfide (PPS), liquid crystal polymer (LCP), polyether nitrile (PEN), polyamide imide (PAI), and polyether ether ketone (PEEK). General heat-resistant resins such as can be used.

The contact surface of the base pad 34 that contacts the stay 35 is formed in a convex shape toward the center in the longitudinal direction, as in the above-described embodiment.

In this embodiment, the stay 35 includes a base portion 35c that contacts the base pad 34 and extends in the paper conveyance direction (vertical direction in FIG. 2), and each end of the base portion 35c on the upstream and downstream sides in the paper conveyance direction. It has a rising portion 35d that extends from the top toward the contact direction of the pressure roller 32 (toward the left side in FIG. 2). By providing the rising portion 35d, the stay 35 has a horizontally elongated cross section extending in the pressing direction of the pressure roller 32, increasing the section modulus and improving the mechanical strength of the stay 35. It becomes possible.

Further, the heater 40 is disposed in a recess formed between the base portion 35c and the rising portions 35d formed on both sides, and the reflective member 38 is disposed between the heater 40 and the stay 35. With this arrangement, the space on the inner peripheral surface side of the fixing belt 31 can be effectively utilized and the diameter of the fixing belt 31 can be reduced.

In the above-described fixing device 6 as well, bent portions 33b are provided on both sides of the metal member 33 in the sheet conveyance direction, and the tip portions 33d extend in a direction intersecting the sheet conveyance direction. By providing the above-mentioned rigidity reducing portion in this bent portion 33b, the bending rigidity of the metal member 33, especially the bending rigidity in the longitudinal direction, can be reduced, and the metal member 33 can be made to easily follow the convex shape of the base pad 34. Can be done. Therefore, it is possible to prevent the nip width of the nip portion N from becoming nonuniform and to prevent the metal member 33 from being twisted in the longitudinal direction.

Although the embodiments of the present invention have been described above, the present invention is not limited to the above-described embodiments, and it goes without saying that various changes can be made without departing from the gist of the present invention.

The image forming apparatus according to the present invention is not limited to the color image forming apparatus shown in FIG. 1, but may be a monochrome image forming apparatus, a copying machine, a printer, a facsimile machine, or a multifunctional device thereof.

In addition to paper P (plain paper), recording media include cardboard, postcards, envelopes, thin paper, coated paper (coated paper, art paper, etc.), tracing paper, OHP sheets, plastic films, prepregs, copper foil, etc. included.

Further, the present invention is not limited to the fixing device as described in the above embodiments, but also includes a drying device that dries ink applied to paper, and furthermore, a drying device that dries ink applied to paper, and furthermore, a drying device that dries ink applied to paper. The present invention is also applicable to heating devices such as laminators for pressure bonding and thermocompression bonding devices such as heat sealers for thermocompression bonding the sealed portions of packaging materials. By applying the present invention to such inkjet image forming apparatuses and thermocompression bonding apparatuses, the rigidity of the metal member, particularly in the longitudinal direction, can be reduced. Therefore, it is possible to prevent the nip width of the nip portion N from becoming nonuniform and to prevent the metal member from being twisted in the longitudinal direction.

1 Image forming device 6 Fixing device (heating device)
31 Fixing belt (fixing member or rotating member)
32 Pressure roller (pressure member or opposing member)
33 Metal member 33a Nip forming part 33b Bending part 33b1 Slit (reduced rigidity part)
33b2 Hole (reduced rigidity)
33b3 Thin wall part (reduced rigidity part)
33c Curved portion 33d Tip portion 34 Base pad (resin member)
35 Stay (support member)
35a Support surface 35b Supported surface 40 Heater (heating member)
50 Nip forming member P Paper (recording medium or heated object)

JP2016-99590A

Claims (10)

a rotating member;
a facing member facing the rotating member;
a nip forming member provided inside the rotating member and forming a nip portion between the rotating member and the opposing member;
A heating device comprising a heating member that heats the rotating member,
The nip forming member has a metal member,
The metal member is provided with a nip forming section extending in the direction of conveyance of the object to be heated, and at least one of an upstream side or a downstream side of the nip forming section in the direction of conveyance of the object to be heated, and a nip forming section extending in the direction of conveyance of the object to be heated. a bent portion bent in a direction different from the longitudinal direction of the nip forming member in a direction that intersects with the nip forming member;
The metal member includes a reduced rigidity portion in the bent portion ,
The heating device is characterized in that the reduced rigidity portion is a slit that is opened at one end of the bent portion in a direction intersecting the longitudinal direction and the thickness direction . The bent portions are provided on the upstream and downstream sides of the nip forming portion in the direction of conveyance of the heated object,
2. The heating device according to claim 1, wherein each bent portion has the stiffness reducing portion. The heating device according to claim 2, wherein the stiffness reducing portions on the upstream side and the downstream side in the heating object conveyance direction are provided at the same position in the longitudinal direction. The metal member is a pressed product of sheet metal material,
The heating device according to any one of claims 1 to 3, wherein a sagging portion formed by press working is arranged on a side of the metal member facing the rotating member. 5. The heating device according to claim 1 , wherein a surface of the metal member that contacts the rotating member is coated with a sliding agent. The heating device according to any one of claims 1 to 5 , further comprising a sliding sheet between the metal member and the rotating member. 7. The heating device according to claim 1, wherein the nip forming member further includes a resin member provided on a side opposite to the nip portion with respect to the metal member. The heating device according to any one of claims 1 to 7 , wherein the nip forming member is the metal member itself. The heating device according to any one of claims 1 to 8 is a fixing device for fixing an image on a recording medium. An image forming apparatus comprising the heating device according to any one of claims 1 to 9 .

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