JP7441426B2 - Nip forming member, heating device, fixing device, image forming device - Google Patents

Description

The present invention relates to a nip forming member, a heating device equipped with the nip forming member, a fixing device, and an image forming apparatus.

A fixing device equipped with a belt member such as a fixing belt has a member that comes into contact with the fixing belt from the inside and forms a fixing nip between the fixing belt and an opposing rotating body such as a pressure roller. A nip forming member is provided.

There are members for forming the above-mentioned nip (nip forming member of the present invention) that are composed of a plurality of members. For example, there is one that has a plate-shaped base material and a high heat conductive member having higher thermal conductivity than the base material on the fixing belt side. In this way, when configuring a member for forming a nip using multiple members, for example, by fixing the base material and the high heat conductive member in position via separate fixing members, it is possible to accurately position these members. can do.

For example, the fixing device disclosed in Patent Document 1 (Japanese Unexamined Patent Publication No. 2016-200802) includes a heat equalizing member with high thermal conductivity that is inscribed in the fixing belt, and a nip formed on the opposite side of the fixing belt with the heat equalizing member in between. It has a member. A sliding sheet is wrapped around the surface of the nip forming member to reduce sliding resistance with the fixing belt. Then, a plate-like member is provided such that the overlapping portion of the ends of the sliding sheet wound around the nip forming member is sandwiched between the nip forming member and the overlapping portion of the sliding sheet. Then, the screw is inserted into the screw hole of the plate member and the screw hole of the sliding sheet, and is screwed into the female thread (not shown in the cross-sectional view) of the nip forming member. By doing so, these members for forming the nip can be provided integrally.

As described above, in the case of a structure in which a fastening hole for fastening a fastening member is provided in a member (base material of the present invention) provided on the opposite side of the belt member with a member having high thermal conductivity such as a heat equalizing member sandwiched therebetween. , the shape of the fastening hole becomes a problem. In other words, when the fastening hole is a through hole, there is a problem that the base material and the high heat conductive member are not in contact with each other at that portion, and the temperature distribution of the high heat conductive member becomes uneven.

In order to solve the above problems, the present invention provides a nip forming member provided inside a rotatable belt member, the nip forming member including a base material and a side of the belt member with respect to the base material. a high heat conductive member having a higher thermal conductivity than the base material, and a fixing member for positionally fixing the base material and the high heat conductive member, the base material and the fixing member having fastening holes. The base material is disposed between the fixing member and the high heat conductive member, and a fastening member is fastened from the fixing member side to the fastening hole of the fixing member and the fastening hole of the base material. The fixing member contacts the high heat conductive member in a direction away from the base material in the overlapping direction of the high heat conductive member, the base material, and the fixing member, and The fastening hole of the base material is a hole portion that is restricted from moving in the direction and does not penetrate the base material toward the high heat conductive member.

According to the present invention, the temperature of the high heat conductive member can be made more uniform.

1 is a schematic configuration diagram of an image forming apparatus. 1 is a sectional view of a fixing device according to an embodiment of the present invention. FIG. 3 is a developed view of each member constituting the nip forming member. (a) to (b) are cross-sectional views showing how the fixing member is attached to the heat equalizing member. (a) to (b) are plan views showing how the fixing member is attached to the heat equalizing member. FIG. 3 is a cross-sectional view of a nip forming member. FIG. 3 is a perspective view of a nip forming member. FIG. 3 is a sectional view of a nip forming member having a configuration different from that of the present invention. FIG. 9 is a cross-sectional view showing how the heat equalizing member of the nip forming member of FIG. 8 is deformed. It is a figure showing the positional relationship between a screw and a stay. FIG. 6 is a cross-sectional view showing a nip forming member according to a different embodiment. FIG. 3 is a cross-sectional view showing a fixing device according to a different embodiment. FIG. 7 is a cross-sectional view showing how the insertion portion of the fixing member is inserted into the insertion hole of the heat equalizing member. FIG. 3 is a perspective view of the base material viewed from the back side.

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, as an example of a heating device equipped with a nip forming member, a fixing device that fixes an image on a sheet of paper as a recording medium, and an image forming apparatus equipped with this fixing device will be described. However, the heating device and the fixing device do not necessarily have to be the same, and the heating device may be one of the devices included in the fixing 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 of 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 section 5 is located at the lower part of the image forming apparatus 1, and includes a paper feed cassette 18 that stores paper P as a recording medium, a paper feed roller 19 that carries out the paper P from the paper feed cassette 18, and the like. ing.

The conveyance path 7 is a conveyance path for conveying the paper P carried out from the paper feed section 5. In addition to the pair of registration rollers 30, a pair of conveyance rollers are used along the conveyance path 7 to reach a paper discharge section 8, which will be described later. are placed appropriately.

The fixing device 6 as a heating device includes a fixing belt 21 that is heated by a heating member, a pressure roller 22 that can press the fixing belt 21, 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 . This paper ejection section 8 is provided with a pair of paper ejection rollers 31 for ejecting the paper P to the outside, and a paper ejection tray 32 for stocking the ejected paper P.

At the top of the image forming apparatus 1, toner bottles 50Y, C, M, 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 50Y, C, M, 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, 9C, 9M, 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 30 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 21 and the pressure roller 22, 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 21, is transported by a pair of transport rollers, and is ejected to a paper ejection tray 32 by a paper ejection roller 31 in a paper ejection section 8.

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

Next, the basic configuration of the fixing device 6 will be explained based on FIG. 2.
As shown in FIG. 2, the fixing device 6 includes a fixing belt 21 as a rotatable belt member (or fixing member), and a pressure roller as a counter rotating body rotatably provided opposite to the fixing belt 21. 22, a halogen heater 23 as a heating member that heats the fixing belt 21, a nip forming member 24 disposed inside the fixing belt 21, and a support that contacts and supports the nip forming member 24 from the back side thereof. A stay 25 as a member, a reflecting member 26 that reflects light emitted from the halogen heater 23 to the fixing belt 21, a temperature sensor 27 as a temperature detection means for detecting the temperature of the fixing belt 21, and a The fixing belt 21 includes a separation member 28 for separating the fixing belt 21 and a pressure means for pressing the pressure roller 22 against the fixing belt 21.

The fixing belt 21 is composed of a thin and flexible endless belt member (including a film). Specifically, the fixing belt 21 includes an inner base material made 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 constituted by a release layer on the outer peripheral side made of 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. By providing the elastic layer, it is possible to absorb irregularities on the surface of the fixing belt 21 and suppress the occurrence of a citron skin image.

The pressure roller 22 includes a core metal 22a, an elastic layer 22b made of foamable silicone rubber, silicone rubber, fluororubber, etc. provided on the surface of the core metal 22a, and a PFA layer provided on the surface of the elastic layer 22. Alternatively, the release layer 22c is made of PTFE or the like. The pressure roller 22 is pressed toward the fixing belt 21 by a pressure means, and is in contact with the nip forming member 24 via the fixing belt 21 . At a location where the pressure roller 22 and the fixing belt 21 come into pressure contact, the elastic layer 22b of the pressure roller 22 is crushed, thereby forming a nip portion N having a predetermined width. Further, the pressure roller 22 is configured to be rotationally driven by a drive source such as a motor provided in the printer body. When the pressure roller 22 is driven to rotate, the driving force is transmitted to the fixing belt 21 at the nip portion N, and the fixing belt 21 is driven to rotate.

In this embodiment, the pressure roller 22 is a solid roller, but it may be a hollow roller. In that case, a heat source such as a halogen heater may be provided inside the pressure roller 22. In addition, when there is no elastic layer, the heat capacity is small and the fixing performance is improved, but when unfixed toner is crushed and fixed, minute irregularities on the belt surface are transferred to the image, causing uneven gloss in the solid areas of the image. may occur. To prevent this, it is desirable to provide an elastic layer with a thickness of 100 μm or more. By providing an elastic layer with a thickness of 100 μm or more, minute irregularities can be absorbed by elastic deformation of the elastic layer, so that uneven gloss can be avoided. The elastic layer 22b may be made of solid rubber, but if there is no heat source inside the pressure roller 22, sponge rubber may be used. Sponge rubber is more desirable because it has better heat insulation and makes it difficult for the fixing belt 21 to lose heat. Further, the fixing member and the opposing rotating body are not limited to being in pressure contact with each other, but may also be configured to simply be brought into contact without applying pressure.

Both ends of the halogen heater 23 are fixed to the side plates of the fixing device 6. The halogen heater 23 is configured to generate heat under output control by a power supply section provided in the printer 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 27. be exposed. By controlling the output of the heater 23 in this manner, the temperature of the fixing belt 21 (fixing temperature) can be set to a desired temperature. Further, as a heating member for heating the fixing belt 21, in addition to a halogen heater, an IH, a resistance heating element, a carbon heater, or the like may be used.

The nip forming member 24 has a longitudinal shape extending in the width direction of the fixing belt 21 or in the axial direction of the pressure roller 22 (a direction perpendicular to the paper surface of FIG. 2, hereinafter also referred to as the longitudinal direction of the nip forming member 24). The fixing belt 21 is disposed in the fixing belt 21 and is in contact with the inner peripheral surface of the fixing belt 21 . The nip forming member 24 supports the nip forming member 24 that has received the pressure from the pressure roller 22 from its inner peripheral surface side, and forms a fixing nip N between it and the pressure roller 22 .

Further, the nip forming member 24 is fixedly supported by a stay 25 from its back side. This prevents the nip forming member 24 from being bent due to the pressure exerted by the pressure roller 22, and provides a uniform nip width along the axial direction of the pressure roller 22. The detailed configuration of the nip forming member 24 will be described later.

The stay 25 is arranged longitudinally along the length of the nip forming member 24 . The stay 25 abuts the nip forming member 24 from its back side in the longitudinal direction, and supports the nip forming member 24 against the pressing force of the pressure roller 22 . In order to satisfy the deflection prevention function of the nip forming member 24, it is desirable to use a metal material with high mechanical strength such as stainless steel or iron, but the stay 25 can also be made of resin.

When the stay 25 "supports" the nip forming member 24, it means that the stay 25, which has a portion extending in the pressing direction of the pressure roller 22 (horizontal direction in the figure) or a thick portion, forms the nip. This refers to contacting the member 24 from the side opposite to the pressure roller 22 (left side in the figure). This suppresses the deflection of the nip forming member 24 due to the pressing force from the pressure roller 22 (in this embodiment, especially the deflection in the longitudinal direction). However, the above contact is not limited to the case where the stay 25 is in direct contact with the nip forming member 24, but also includes the case where the stay 25 is in contact with the nip forming member 24 via another member as in the present embodiment. "Abutment via another member" means that another member is sandwiched between the stay 25 and the nip forming member 24 in the left-right direction of the figure, and at least a portion of the other member is in a corresponding position. 25 is in contact with another member, and the other member is in contact with the nip forming member 24. Furthermore, the term "extending in the pressing direction" mentioned above is not limited to extending in the same direction as the pressing direction of the pressure roller 22, but extending in a direction at a certain angle from the pressing direction of the pressure roller 22. This also includes cases where there are Even in these cases, it goes without saying that the stay 25 can suppress the deflection of the nip forming member 24 against the pressing force from the pressure roller 22.

The reflecting member 26 is disposed between the stay 25 and the halogen heater 23. In this embodiment, the reflecting member 26 is fixed to the stay 25. Examples of the material for the reflective member 26 include aluminum and stainless steel. By arranging the reflecting member 26 in this way, the light emitted from the halogen heater 23 to the stay 25 side is reflected to the fixing belt 21. Thereby, the amount of light irradiated onto the fixing belt 21 can be increased, and the fixing belt 21 can be heated efficiently. Further, since it is possible to suppress the radiant heat from the halogen heater 23 from being transmitted to the stay 25 and the like, energy saving can also be achieved.

Further, instead of providing the reflective member 26 as in this embodiment, the surface of the stay 25 on the halogen heater 23 side may be subjected to mirror treatment such as polishing or painting to form a reflective surface. Further, it is desirable that the reflectance of the reflecting surface of the reflecting member 26 or the stay 25 is 90% or more.

However, since there are restrictions on the shape and material of the stay 25 in order to ensure its strength, it is better to separately provide the reflective member 26 as in this embodiment, which will give you more flexibility in selecting the shape and material, and the reflective member 26 and stay 25 can be specialized for their respective functions. Further, by providing the reflective member 26 between the halogen heater 23 and the stay 25, the position of the reflective member 26 with respect to the halogen heater 23 becomes closer, so that the fixing belt 21 can be heated efficiently.

Furthermore, in order to further improve the heating efficiency of the fixing belt 21 due to light reflection, it is necessary to consider the orientation of the reflective surface of the reflective member 26 or the stay 25. For example, if the reflecting members 26 are arranged concentrically around the halogen heater 23, the light will be reflected toward the halogen heater 23, which will reduce the heating efficiency accordingly. On the other hand, if part or all of the reflecting member 26 is arranged in a direction other than the halogen heater 23 to reflect light toward the fixing belt, the amount of light reflected toward the halogen heater 23 will be reduced. Therefore, the heating efficiency by reflected light can be improved.

Further, the fixing device 6 according to the present embodiment has various structural improvements in order to further improve energy saving and first print time.
Specifically, the fixing belt 21 can be directly heated at locations other than the nip portion N by the halogen heater 23 (direct heating method). In this embodiment, nothing is interposed between the halogen heater 23 and the left part of the fixing belt 21 in FIG. 2, and the radiant heat from the halogen heater 23 is directly applied to the fixing belt 21 in that part.

Further, in order to reduce the heat capacity of the fixing belt 21, the fixing belt 21 is made thin and small in diameter. Specifically, the thickness of each of the base material, elastic layer, and release layer constituting the fixing belt 21 is set in the range of 20 to 50 μm, 100 to 300 μm, and 10 to 50 μm, and the overall thickness is It is set to 1 mm or less. Further, the diameter of the fixing belt 21 is set to 20 to 40 mm. In order to further reduce the heat capacity, the entire thickness of the fixing belt 21 is preferably 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.

In this embodiment, the diameter of the pressure roller 22 is set to 20 to 40 mm, and the diameter of the fixing belt 21 and the diameter of the pressure roller 22 are configured to be equal. However, it is not limited to this configuration. For example, the diameter of the fixing belt 21 may be smaller than the diameter of the pressure roller 22. In that case, the curvature of the fixing belt 21 at the nip portion N becomes larger than the curvature of the pressure roller 22, so that the recording medium discharged from the nip portion N is easily separated from the fixing belt 21.

The basic operation of the fixing device according to this embodiment will be described below with reference to FIG. 2.
When the power switch of the printer body is turned on, power is supplied to the halogen heater 23, and the pressure roller 22 starts rotating clockwise in FIG. 2 (see arrow B1). As a result, the fixing belt 21 is driven to rotate counterclockwise in FIG. 2 (see arrow B2) due to the frictional force with the pressure roller 22.

Thereafter, the paper P carrying the unfixed toner image T in the image forming process described above is conveyed in the direction of arrow C1 in FIG. 2 while being guided by a guide plate, and the fixing belt 21 and the pressure roller are in pressure contact 22 into the nip portion N. Then, the toner image T is fixed on the surface of the paper P by the heat generated by the fixing belt 21 heated by the halogen heater 23 and the pressing force between the fixing belt 21 and the pressure roller 22.

The paper P on which the toner image T has been fixed is carried out from the nip portion N in the direction of arrow C2 in FIG. At this time, the leading edge of the paper P comes into contact with the leading edge of the separation member 28, so that the paper P is separated from the fixing belt 21. Thereafter, as described above, the separated sheets P are discharged from the machine by the paper discharge rollers and are stocked on the paper discharge tray.

Next, a more detailed configuration of the nip forming member 24 will be described.

As shown in FIGS. 2 and 3, the nip forming member 24 includes a base material 41, a heat equalizing member 42 as a high heat conductive member, a screw 43 as a fastening member, and a fixing member 44 for fastening the screw 43. It is equipped with The base material 41 and the heat equalizing member 42 extend in the longitudinal direction of the nip forming member 24.

The base material 41 is made of a heat-resistant member, such as ceramic, glass, inorganic materials such as aluminum, rubbers such as silicone rubber and fluororubber, PTFE (tetrafluoroethylene), and PFA (tetrafluoroethylene). PI (polyimide), PAI (polyamideimide) ), PPS (polyphenylene sulfide), PEEK (polyether ether ketone), LCP (liquid crystal plastic, liquid crystal polymer), phenol resin, nylon, aramid, or a combination of these resins can be used.

In this embodiment, the base material 41 is made of a resin material, and its thermal conductivity is set to about 0.2 to 0.3 W/m·K, for example. As the resin material forming the base material 41, for example, liquid crystal polymer (LCP), which has excellent heat resistance and moldability, can be used.

The base material 41 has a fastening hole 41a on its longitudinal center side, into which the screw 43 is fastened together with the fixing member 44. The fastening hole 41a is a hole that is provided halfway in the thickness direction of the base material 41 and does not penetrate through the base material 41.

As shown in FIG. 3, the base material 41 has a plurality of protrusions 41b that protrude toward the stay 25 side. A plurality of protrusions 41b are arranged in the longitudinal direction of the base material 41, and are provided in two rows in the lateral direction. The protruding portion 41b is a positioning portion that comes into contact with the stay 25 and positions the nip forming member 24 with respect to the stay 25.

The heat equalizing member 42 is a member that comes into contact with the fixing belt 21 from its inner peripheral surface side (see FIG. 2). The heat equalizing member 42 is made of a member having higher thermal conductivity than the base material 41. Specifically, in this embodiment, SUS is used, and its thermal conductivity is set to 16.7 to 20.9 W/m·K. Alternatively, a material with high thermal conductivity such as a copper-based material (eg, thermal conductivity of 381 W/m·K) or an aluminum-based material (eg, thermal conductivity of 236 W/m·K) can also be used.

A heat equalizing member 42 with good thermal conductivity is provided on the fixing belt 21 side of the nip forming member 24, and the heat equalizing member 42 is brought into contact with the fixing belt 21 in its width direction, thereby dissipating the heat of the fixing belt 21. By moving the fixing belt 21 in the width direction to make it uniform, temperature unevenness in the width direction of the fixing belt 21 can be suppressed.

The heat equalizing member 42 has bent portions 42a provided on both sides thereof in the longitudinal direction. As shown in FIG. 2, in the present embodiment, the bent portions 42a of the heat equalizing member 42 are arranged to bend the metal plate in a direction substantially perpendicular to the width direction ( It is formed by bending in the left direction in FIG. 2 (in the direction opposite to the nip portion N).

As shown in FIG. 3, the heat equalizing member 42 has a first insertion hole 42b for attaching the fixing member 44 and a second insertion hole 42b on both sides in the width direction at the center side in the longitudinal direction of both bent portions 42a, 42a. An insertion hole 42c is provided. The portion of the bent portion 42a where the first insertion hole 42b and the second insertion hole 42c are provided has a shape that partially protrudes in the bending direction compared to other portions of the bent portion 42a. The second insertion hole 42c is a hole that penetrates the heat equalizing member 42 in the lateral direction (vertical direction in FIG. 2). Further, the first insertion hole 42b, like the second insertion hole 42c, has a shape that penetrates both sides of the heat equalizing member 42 in the transverse direction and also opens to one side of the heat equalizing member 42 in the thickness direction.

The heat equalizing member 42 is provided with constricted portions 42d at both ends in the longitudinal direction, the width of which decreases in width toward the ends.

The fixing member 44 is a member separate from the base material 41 and the heat equalizing member 42, which is provided for positioning the base material 41 and the heat equalizing member 42. The fixing member 44 has a fastening hole 44a for fastening the screw 43 at its center, and has a first insertion part 44b and a second insertion part 44c at both ends thereof. The first insertion portion 44b is provided with a narrow portion 44b1 whose width is partially narrowed.

Next, a method for assembling each of the above members will be explained using FIGS. 4 and 5.
First, as shown in FIGS. 4A and 5A, the fixing member 44 is inserted from above the base material 41 and the heat equalizing member 42 (see the direction of arrow D1 in FIG. 4A). Specifically, as shown in FIG. 5(a), the narrow portion 44b1 of the fixing member 44 is inserted into the first insertion hole 42b of the heat equalizing member 42. Then, by sliding the fixing member 44 toward the second insertion hole 42c (see arrow D2 direction), the second insertion portion 44c of the fixing member 44 is inserted into the second insertion hole 42c of the heat equalizing member 42. Thereby, the fixing member 44 can be attached to the heat equalizing member 42, as shown in FIGS. 4(b) and 5(b). In this way, by partially providing the narrow portion 44b1 in the fixing member 44 and opening the first insertion hole 42b on one side of the heat equalizing member 42 in the thickness direction, the fixing member 44 can be attached to the heat equalizing member 42. It can be inserted from above. Therefore, compared to the case where the first insertion portions 44b and 44c on both sides are slid and inserted into the first insertion hole 42b and the second insertion hole 42c, the operation is easier. This also prevents the fixing member 44 and the heat equalizing member 42 from being caught during insertion and causing pressure in the insertion direction to deform the fixing member 44 and the heat equalizing member 42.

As shown in FIG. 5(a), the wide part of the first insertion part 44b of the fixing member 44 has a width W1, and the narrow part 44b1 has a width W2, and as shown in FIG. Assuming that the wide portion of the hole 42b is the width L1, and the narrow portion on the opening side is the width L2, W2<L2<W1<L1. When W2<L2, the fixing member 44 can be moved in the direction of the arrow D1 with respect to the heat equalizing member 42 as described above, and the narrow portion 44b1 can be inserted into the first insertion hole 42b of the heat equalizing member 42. Further, since L2<W1, in the state shown in FIG. 5(b), the wide portion of the first insertion portion 44b comes into contact with the wall surface portion forming the narrow portion on the opening side of the first insertion hole 42b, so that the fixing member 44 is It is possible to prevent the heat equalizing member 42 from falling off in the direction perpendicular to the plane of the paper in FIG. 5(b) (the direction opposite to the arrow D1 direction in FIG. 13). Further, the first insertion hole 42b has a tapered shape H at the opening on the insertion side. Thereby, the first insertion portion 44b can be smoothly inserted into the first insertion hole 42b. However, a configuration in which the tapered shape H is not provided may also be used.

Further, as shown in FIG. 5(a), the width W3 on the second insertion part 44c side of the fixing member 44, the width W4 of the second insertion part 44c, and the width L3 of the second insertion hole 42c of the heat equalizing member 42. Then, W4<L3<W3. Since W4<L3, the second insertion portion 44c can be inserted into the second insertion hole 42c. Furthermore, since L3<W3, the contact surface 44e, which is the lower end surface of the fixing member 44 (the end surface on the downstream side in the insertion direction of the fixing member 44 with respect to the heat equalizing member 42), is connected to the abutted surface 42e provided on the bent portion 42a. It can be brought into contact with the Note that the above-mentioned widths W1 to W4 and widths L1 to L3 are widths in the same direction as the longitudinal direction of the heat equalizing member 42.

By the way, the fixing member 44 has a heat equalizing member of the fixing member 44 by inserting the first insertion portion 44b and the second inserting portion 44c into the first insertion hole 42b and the second insertion hole 42c of the heat equalizing member 42, respectively. 42 is positioned in the left-right direction in FIG. 5(b). That is, the side portions of the first insertion portion 44b and the second insertion portion 44c come into contact with the side wall portions forming the first insertion hole 42b and the second insertion hole 42c, so that the view of the fixing member 44 with respect to the heat equalizing member 42 5(b) is restricted from moving in the left and right direction. Thereby, the base material 41 fastened to the fixing member 44 is positioned with respect to the heat equalizing member 42 in its longitudinal direction. In addition, the second insertion portion 44c is inserted into the second insertion hole 42c, and the contact surface 44e, which is the lower end surface of the fixing member 44 (the end surface of the fixing member 44 on the downstream side in the insertion direction with respect to the heat equalizing member 42), is bent. By abutting against the abutted surface 42e provided on the portion 42a, positioning in the vertical direction in the figure is performed.

By the above operation, the fixing member 44 is positioned with respect to the base material 41, and the fastening hole 44a of the fixing member 44 and the fastening hole 41a of the base material 41 can be aligned. That is, by simply attaching the fixing member 44 to the heat equalizing member 42, the fastening holes 44a and 41a can be aligned, and the screws 43 can be fastened. Therefore, there is no need to align the fastening holes with each other, and the time required to assemble the nip forming member can be shortened, resulting in improved assemblability. Further, since the alignment accuracy between the fastening hole 44a and the fastening hole 41a is improved, the alignment accuracy between the base material 41 and the heat equalizing member 42 can also be improved. Furthermore, by improving the alignment accuracy between the fastening hole 44a and the fastening hole 41a, it becomes possible to make the fastening hole 44a smaller, and it becomes possible to provide the fixing member 44 with a minimum size. The cost of the fixing member 44 can be kept low.

With the fastening hole 44a and the fastening hole 41a aligned, the fixing member 44 and the base material 41 are fastened by fastening the screw 43 (screwing together, so-called tightening the screw), and the fixing member 44 and the base material 41 can be fixed. Thereby, as shown in FIGS. 6 and 7, the base material 41 and the heat equalizing member 42 are fixed, and the nip forming member 24 is assembled.

In this embodiment, the fixing member 44 is attached to the heat equalizing member 42 and the fixing member 44 and the base material 41 are fastened together with the screws 43, so that the fixing member 44 and the base material 41 can be evenly connected to each other via the fixing member 44. The heat member 42 can be fixed in position. More specifically, by inserting the first insertion part 44b and the second insertion part 44c of the fixing member 44 into the first insertion hole 42b and the second insertion hole 42c of the heat equalizing member 42, the fixing member 44 and the base material 41, movement of the heat equalizing member 42 in the longitudinal direction and the thickness direction with respect to the heat equalizing member 42 is restricted. Further, the movement of the base material 41 in the lateral direction is restricted by bent portions 42a provided on both sides of the heat equalizing member 42 in the lateral direction. With these, the base material 41 is positioned with respect to the heat equalizing member 42.

Furthermore, in this embodiment, when inserting the corresponding first insertion part 44b of the fixing member 44 into one of the first insertion holes 42b of the heat equalizing member 42 (when inserting in the direction of arrow D1 in FIG. 4a), The side walls of the projections 41b disposed on both sides of the member 44 function as guide portions that guide the fixing member 44 in the insertion direction (from one side in the lateral direction to the other side) (see FIG. 5a). This improves workability when inserting the fixing member 44 into the first insertion hole 42b. However, apart from the protrusion 41b, a rib shape extending from one side in the transverse direction to the other side may be provided at a corresponding position to serve as a guide portion.

Further, since the nip forming member 24 slides on the fixing belt as the fixing belt rotates, a load accompanying the sliding is also applied to the above-mentioned fixed position portion. However, by fastening the screws through a separate member as in this embodiment, it is advantageous in terms of strength compared to a structural fixing method by fitting with nails or the like.

By the way, the fastening hole 41a provided in the base material 41 is a hole portion that does not penetrate the base material 41 in the thickness direction toward the heat equalizing member 42 side. Therefore, in the longitudinal direction of the nip forming member 24, the base material 41 and the heat equalizing member 42 are in contact even at the position where the screw 43 is fastened, and there is a gap between the heat equalizing member 42 and the base material 41. Not formed. Specifically, a contact surface 41g, which is a portion of the base material 41 corresponding to the fastening hole 41a, is in contact with the heat equalizing member 42 (see FIG. 4).

For example, as a configuration different from this embodiment, as shown in FIG. 8, in the case of a configuration in which the fastening hole 41a' provided in the base material 41 is a through hole, the screw 43 and the heat equalizing member 42 are connected at the fastening hole 41a' portion. A gap E is formed between them. In other words, the part of the heat equalizing member 42 facing the fastening hole 41a' does not contact the base material 41 or the screw 43, and no heat transfer to these members occurs, so this part of the heat equalizing member 42 As a result, the temperature of the fixing belt becomes uneven in its width direction. Furthermore, as the temperature of the heat equalizing member 42 partially increases, a difference occurs in the amount of expansion, and as shown in FIG. I end up. When such deformation occurs, the pressure in the nip portion N becomes partially weak, resulting in poor image fixation due to insufficient pressure, or the sliding load between the fixing belt and the nip forming member 24 increases at the deformed portion. This may accelerate the wear of the fixing belt.

In order to solve the above-mentioned problems, in this embodiment, the fastening hole 41a is made into a non-penetrating hole, thereby preventing the heat equalizing member 42 from becoming partially heated and deformed, resulting in poor image fixation and wear of the fixing belt. Promotion can be prevented.

FIG. 14 is a perspective view of the base material 41 viewed from the back side.
As shown in FIG. 14, the base material 41 contacts the heat equalizing member 42 in the shaded area of the figure. In other words, the base material 41 is in contact with the heat equalizing member 42 in the longitudinal direction at three locations, namely both ends and the center, and is in contact with the heat equalizing member 42 in the recess between both ends and the center. It's contact. Since the base material 41 is in continuous contact with the heat equalizing member 42 in the longitudinal direction, the pressing force that the heat equalizing member 42 receives from the pressure roller 22 via the fixing belt 21 is applied to the base material 41 and the base material 41. The contacting stays 25 can be received uniformly over the longitudinal direction (see FIG. 2). Further, as shown in FIG. 4A, the contact surface 41g of the base material 41 contacts the heat equalizing member 42 at a location corresponding to the fastening hole 41a of the base material 41. In other words, when viewed from the thickness direction of the base material 41, the contact surface 41g of the base material 41 contacts the heat equalizing member 42 at the location where the fastening hole 41a is provided. Thereby, as shown in FIG. 14, the contact portion of the base material 41 with the heat equalizing member 42 can be provided continuously in the longitudinal direction. In addition, when the fastening hole 41a is provided in a position where the base material 41 does not contact the heat equalizing member 42 over the longitudinal direction in the transverse direction, it is also possible to form a hole that penetrates the fastening hole 41a.

As shown in FIG. 10, in the nip forming member 24 of this embodiment, the projection 41b of the base material 41 contacts the stay 25, and the nip forming member 24 is supported by the stay 25 from its back side. In this state, a gap of distance F is provided between the stay 25 and the screw 43 in the vertical direction of the figure (the insertion direction of the screw 43 into the fixing member 44 or the base material 41, and the thickness direction of the base material 41, etc.). . By providing a gap in this way, even if the screw 43 is heated and expands, the expansion can be released, preventing the expanded screw 43 from pushing the base material 41 and deforming the nip portion N, and preventing nip formation. Damage due to plastic deformation of the member 24 can be prevented. Furthermore, if the length of the threaded part 43a (fastening part 43a) of the screw 43 is G, by making the gap distance F smaller than the length G of the threaded part 43a, even if the fastening of the screw 43 becomes loose, the screw The head of the screw 43 comes into contact with the stay 25, and the screw 43 can be prevented from falling off from the base material 41 and the fixing member 44. In this embodiment, the distance F of the gap between the stay 25 and the screw 43 is defined as above, but when another member is interposed between the stay 25 and the screw 43, the distance between the screw 43 and the other member is It may be the distance of For example, when a mounting member is provided between the stay 25 and the nip forming member 24 to insert the protrusion 41b of the base material 41 and attaching the nip forming member 24, there is a gap between this mounting member and the screw 43. The above effect can be obtained by providing a gap or by making the distance F of this gap smaller than the length G of the threaded portion 43a. However, in FIG. 10, for convenience, the screw 43 is not shown in a cross-sectional view, but is shown so that the screw portion 43a and other parts can be distinguished.

Further, in this embodiment, the base material 41 and the fixing member 44 have stepped portions (step shapes) 41f and 44d on opposing sides thereof, each having a shape corresponding to the shape of each stepped portion (see FIG. 4b). Specifically, the surface where the fixing member 44 and the base material 41 come into contact is set as a reference plane, and each of the fixing member 44 and the base material 41 is placed above the reference plane in the upper direction in FIG. 4(b). (More specifically, in the thickness direction of the base material 41, the surface is lowered toward the heat equalizing member 42). Thereby, the fastening hole 41a and the fastening hole 44a can be aligned by simply aligning the stepped portions 41f and 44d. This improves the ease of assembling the nip forming member 24 and prevents the screw 43 from being fastened in an inclined state. In addition, the shape of the fixing member 44 is asymmetrical in the transverse direction, and it is also possible to prevent incorrect assembly when the fixing member 44 is turned upside down or upside down. However, as shown in FIG. 11, the fixing member 44 may be a plate-like member without a stepped portion.

Furthermore, by setting the mounting position of the fixing member 44 and the fixing position using the screws 43 at approximately the center in the longitudinal direction of the base material 41 and the heat equalizing member 42 (see FIG. 7), positioning at the center in the longitudinal direction is possible. This makes it difficult for the base material 41 and the heat equalizing member 42 to be misaligned in either direction. Thereby, temperature unevenness in the longitudinal direction of the fixing belt 21 and pressure deviation in the longitudinal direction of the fixing nip can be suppressed as much as possible. Note that the longitudinal center portion of the base material 41 and the heat equalizing member 42 refers to the middle region when these members are divided into three in the longitudinal direction, and the most preferable position is exactly in the middle of the longitudinal direction. This is the case when it is fixed at .

Further, in this embodiment, the base material 41 is made of a resin material, and the heat equalizing member 42 is made of a material different from a metal material, and the coefficients of thermal expansion thereof are different. Therefore, a difference occurs in the coefficient of thermal expansion of both members due to the heat of the heater 23, but by fixing the base material 41 and the heat equalizing member 42 at one point in the center in the longitudinal direction, the expansion to both sides in the longitudinal direction is can be released, and damage to the heat equalizing member 42 can mainly be prevented.

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 nip forming member of the present invention can also be applied to a fixing device 6 equipped with a plurality of heating members shown in FIG. 12 below. Hereinafter, the explanation will focus on the parts that are different from the fixing device shown in FIG. 2 described above, and the description of common configurations will be omitted as appropriate.

As shown in FIG. 12, the fixing device 6 includes a fixing belt 21 as a belt member, a pressure roller 22, a nip forming member 24, etc., as in the above-described embodiment. Furthermore, the fixing device 6 of this embodiment has two heaters 23A and 23B. One of the heaters 23A and 23B has a heat generating area at the center in the longitudinal direction corresponding to small size paper, and the other has heat generating areas at both ends in the longitudinal direction corresponding to large size paper. In this embodiment, halogen heaters are used as the heaters 23A and 23B, but they may also be induction heating devices, resistance heating elements, carbon heaters, or the like.

The stay 25 provided in the fixing device 6 has a T-shaped cross section, and has an upright portion 25a on the side opposite to the fixing nip N side. This standing portion 25a separates the heaters 23A and 23B.

The heaters 23A and 23B are configured to generate heat under output control by a power supply unit provided in the printer body, and the output control is performed by detecting the temperature of the belt surface by a temperature sensor provided on the outer periphery of the fixing belt 21. It is done based on results. By controlling the output of the heater in this manner, the temperature of the fixing belt 21 (fixing temperature) can be set to a desired temperature.

In addition, reflective members 26A and 26B are arranged between the stay 25 and the heaters 23A and 23B to increase the heating efficiency of the heaters 23A and 23B to the fixing belt 21, and to heat the stay 25 with the radiant heat from the heaters 23A and 23B. This suppresses wasteful energy consumption caused by

Also in the fixing device 6 described above, the nip forming member 24 having the above-described configuration can be applied, and thereby the above-described effects can be obtained. For example, by making the fastening hole 41a a non-penetrating hole, it is possible to prevent the heat equalizing member 42 from becoming partially heated and deformed, thereby preventing poor image fixation and accelerated wear of the fixing belt.

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.

Furthermore, the device equipped with a heating device to which the nip forming member of the present invention is applied is not limited to the fixing device described in the above embodiment, but also includes a drying device that dries ink applied to paper, and furthermore, a device equipped with a heating device that applies the nip forming member of the invention. The present invention can also be applied to heating devices such as a laminator that thermocompresses a film as a member onto the surface of a sheet such as paper, and a heat sealer that thermocompresses the seal portion of a packaging material. By applying the present invention to such a device, the temperature of the highly thermally conductive member can be made more uniform.

1 Image forming device 6 Fixing device (heating device)
21 Fixing belt (belt member)
22 Pressure roller (opposed rotating body)
23 Halogen heater (heating member)
24 Nip forming member 25 Stay (supporting member)
41 Base material 41a Fastening hole 41b Projection (positioning part)
41f Step part (step shape)
42 Heat equalizing member (high heat conductive member)
42a Bend portion 42b First insertion hole 42c Second insertion hole 42e Abutted surface 43 Screw (fastening member)
43a Threaded part (fastening part)
44 Fixing member 44a Fastening hole 44b First insertion part 44c Second insertion part 44d Step part (step shape)
44e Contact surface (end surface)
45 Holding member N Fixing nip (nip part)
P Paper (recording medium)

Japanese Patent Application Publication No. 2016-200802

Claims (10)

A nip forming member provided inside a rotatable belt member,
The nip forming member is
base material and
a high heat conductive member that is provided on the side of the belt member with respect to the base material and has a higher thermal conductivity than the base material;
A fixing member for positionally fixing the base material and the high thermal conductive member,
The base material and the fixing member have fastening holes,
The base material is disposed between the fixing member and the high heat conductive member,
A fastening member is fastened to the fastening hole of the fixed member and the fastening hole of the base material from the side of the fixed member,
The fixing member is in contact with the high heat conductive member in a direction away from the base material in the overlapping direction of the high heat conductive member, the base material, and the fixing member, and movement is regulated,
A nip forming member, wherein the fastening hole of the base material is a hole portion that does not penetrate the base material toward the high heat conductive member. The nip forming member according to claim 1, wherein the base material and the high heat conductive member are in contact with each other in the longitudinal direction of the high heat conductive member. The nip forming member according to claim 1 or 2, wherein the base material and the high heat conductive member are in contact with each other at a position corresponding to the fastening hole of the base material. The nip forming member according to any one of claims 1 to 3, wherein the base material and the fixing member have corresponding step shapes. The fixing member is configured such that an end surface in a lateral direction intersecting the longitudinal direction of the high heat conductive member is brought into contact with an abutted surface provided on the high heat conductive member in a direction perpendicular to the overlapping direction, The nip forming member according to any one of claims 1 to 4, wherein the fastening hole of the fixing member and the fastening hole of the base material are aligned in the assembly direction. The belt member;
a counter rotating body disposed opposite to the belt member;
The nip forming member according to any one of claims 1 to 5, which abuts the opposing rotating body via the belt member and forms a nip portion between the belt member and the opposing rotating body. heating device. further comprising a support member that supports the nip forming member from a side opposite to the nip portion,
The heating device according to claim 6, wherein a gap is provided between the support member and the fastening member in a direction in which the fastening member is inserted into the fixing member. 8. The length of the gap provided between the support member and the fastening member in the insertion direction of the fastening member into the fixing member is smaller than the length of the fastening portion of the fastening member. heating device. A fixing device that fixes toner on a recording medium using heat, the fixing device comprising the heating device according to claim 6 . An image forming apparatus comprising the fixing device according to claim 9.

Images