JP6822117B2 - Fixing device and image forming device - Google Patents

Description

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

In recent years, there has been an increasing market demand for energy saving and high speed for image forming devices such as printers, copiers, facsimiles, and multifunction devices having at least two functions thereof.
In the image forming apparatus, the unfixed toner image is transferred to the recording material sheet, printing paper, photosensitive paper, electrostatic recording paper, etc. by the image transfer method or the direct method by the image forming process such as electrophotographic recording, electrostatic recording, and magnetic recording. It is formed on a recording material (recording medium). As a fixing device for fixing an unfixed toner image, a contact heating type fixing device such as a thermal roller method, a film heating method, and an electromagnetic induction heating method is widely adopted.

In recent years, belt-type fixing devices have further warm-up time (time required from normal temperature to a predetermined printable temperature (reload temperature) such as when the power is turned on) and first print time (after receiving a print request). It is desired to shorten the time required to perform the printing operation after the printing preparation and complete the paper ejection. In addition, as the speed of the image forming apparatus increases, the number of sheets to be passed per unit time increases and the required amount of heat increases, so that the amount of heat is insufficient especially at the beginning of continuous printing (so-called temperature drop) becomes a problem. ing.

Therefore, a fixing device has been proposed that has high energy saving and can further shorten the first print time from the standby state of heating by directly heating the endless belt (see, for example, Patent Document 1). ..
In Patent Document 1, for the purpose of transferring the heat of the end heat source to make the temperature of the fixing member uniform in the longitudinal direction, the surface of the heat transfer assisting member facing the inner surface of the fixing belt of the rectangular parallelepiped nip forming member is provided. A configuration that is fitted and integrated so as to cover is disclosed. By using the heat transfer assisting member for the nip portion, the temperature rise at the end portion of the fixing belt is suppressed and the temperature unevenness in the longitudinal direction is also improved.

However, it is a method of directly heating the fixing belt, which is an endless and tubular fixing member with a low heat capacity, as adopted in Patent Document 1, and further uses a heat transfer assisting member for the nip portion to increase the height of the fixing belt. In a configuration that slides under a load, the following problems occur. That is, the bent portions on the upstream side and the downstream side in the circumferential direction of the heat transfer assisting member make line contact with the inner surface of the fixing belt, and both ends in the longitudinal direction of the heat transfer assisting member and the inner surface of the fixing belt make point or line contact to fix. Since it slides on the inner surface of the belt with a load higher than that of the nip portion, there is a problem that the belt may be scraped, kink, or damaged, and the durability may be lowered. The term "kink" refers to a state in which the fixing belt is deformed and cannot be completely restored.
In Patent Document 1, the heat transfer assisting member is indispensable as a means for solving the problem, but when the problem is different as in the present invention, the heat transfer assisting member is not necessarily a necessary structure, and at least the nip forming member is not required. It suffices to have.

The present invention has been made in view of the above circumstances, and the contact regions on the upstream side and the downstream side in the rotation direction of the fixing belt in the nip forming member provided so as to come into contact with the inner surface of the fixing belt (fixing member) are formed. The purpose is to prevent scraping, kinking, and damage of the fixing belt by preventing it from rubbing against the inner surface of the fixing belt with a high load. In addition, "rubbing" means a frictional state while sliding.

In order to achieve the above object, the present invention comprises a flexible and rotatable endless fixing member, an opposing member arranged outside the fixing member and facing the fixing member, and the fixing member. A fixing heat source that heats at least the central portion of the recording medium holding region in the longitudinal direction of the above, and a nip that is provided inside the fixing member and forms a nip portion that holds the recording medium between the fixing member and the facing member. A region where the forming member and the nip forming member come into contact with the inner surface of the fixing member, which is provided at least one of the upstream side and the downstream side in the rotation direction of the fixing member, and the fixing member. A rotating member that follows the rotation of the rotating member, and the rotating member is a truncated cone or a twin.
A fixing device you being a frustoconical.

According to the present invention, according to the above configuration, it is possible to eliminate rubbing between the nip forming member and the inner surface of the fixing member under a high load, and prevent scraping, kinking, and breakage of the fixing member.

It is a schematic block diagram of a color printer as an image forming apparatus to which this invention is applied. It is sectional drawing of the fixing device to which this invention is applied. It is an exploded perspective view which shows the specific structure of the nip forming member and the heat transfer assisting member of the fixing device to which this invention is applied. (A) is a view showing the configuration around the nip portion of the fixing device according to the first embodiment, and is a front view showing a configuration in which rotating members are provided on the nip inlet side and the nip outlet side of the heat transfer assisting member, (b). ) Is a perspective view of (a). It is a figure which shows the structure around the nip part of the fixing device which concerns on Example 2, and is provided with both ends of the heat transfer assisting member in the longitudinal direction on the nip entrance side, and a plurality of truncated cone-shaped rotating members between them. It is a perspective view which shows the structure. (A) is a perspective view showing a rotating member according to a second embodiment, and (b) is a perspective view showing a rotating member according to a modified example of the second embodiment. FIG. 5 is a cross-sectional view of a fixing device not provided with an end heater and a heat transfer assisting member to which the present invention can be applied.

Hereinafter, embodiments of the present invention including examples will be described in detail with reference to the drawings. There is no risk of confusion with respect to components (members and components) having the same function and shape, etc., throughout the embodiments and examples, including the fixing device and the image forming device to which the present invention can be applied. After the explanation is given once, the explanation will be omitted by adding the same reference numerals.

FIG. 1 shows an image forming apparatus to which the present invention can be applied. In the figure, the image forming apparatus 100 as a conventional example to which the present invention can be applied is a tandem color printer in which image forming portions forming a plurality of color images are juxtaposed along the moving direction of the intermediate transfer belt.
The image forming apparatus 100 is a photoconductor drum 20Y as an image carrier capable of forming an image corresponding to each of the colors decomposed into yellow (Y), cyan (C), magenta (M), and black (Bk). , 20C, 20M, 20Bk.

The toner image as a visible image formed on each of the photoconductor drums 20Y, 20C, 20M, and 20Bk is superimposed on the intermediate transfer belt 11 as an intermediate transfer body that can move in the direction of arrow A1 while facing each photoconductor drum. At the same time, the primary transfer is performed. Each color image is superimposed and transferred on the intermediate transfer belt 11 by this primary transfer, and then the toner image is collectively transferred to the paper S as an example of the recording medium by the secondary transfer step.
Hereinafter, when the photoconductor drums 20Y, 20C, 20M, and 20Bk are comprehensively described, they are also referred to as the photoconductor drums 20. A device for performing image forming processing according to the rotation of the photoconductor drum 20 is arranged around each photoconductor drum 20.

Here, a device for performing image forming processing will be described on behalf of the photoconductor drum 20Bk that forms a black image.
A charging device 30Bk for performing image forming processing, a developing device 40Bk, a primary transfer roller 12Bk, and a cleaning device 50Bk are arranged in this order around the photoconductor drum 20Bk along the rotation direction of the photoconductor drum 20Bk.
After charging by the charging device 30Bk, optical writing is performed on the surface of the photoconductor drum 20Bk by the optical writing device 8 using the writing light Lb based on the image information, and an electrostatic latent image is formed. The formed electrostatic latent image is visualized as a toner image by the developing device 40Bk.

The toner images formed on the photoconductor drums 20Y, 20C, 20M, and 20Bk are primarily transferred by being superimposed on the same position of the intermediate transfer belt 11 in the process of moving the intermediate transfer belt 11 in the direction of arrow A1. This primary transfer is performed from the upstream side to the downstream side in the arrow A1 direction by applying a voltage by the primary transfer rollers 12 arranged to face the photoconductor drums 20Y, 20C, 20M, and 20Bk with the intermediate transfer belt 11 interposed therebetween. The timing is staggered toward.
The photoconductor drums 20Y, 20C, 20M, and 20Bk are arranged in this color order from the upstream side in the moving direction of the intermediate transfer belt 11. The photoconductor drums 20Y, 20C, 20M, and 20Bk are arranged in an image station for forming yellow, cyan, magenta, and black images, respectively.

The image forming apparatus 100 is arranged so as to face the four image stations that perform image forming processing for each color and above each of the photoconductor drums 20Y, 20C, 20M, and 20Bk, and the intermediate transfer belt 11 and the primary transfer roller. It has an intermediate transfer belt unit 10 having 12Y, 12C, 12M, and 12Bk.
Further, the image forming apparatus 100 faces the secondary transfer roller 5 as a secondary transfer means which is arranged so as to face the intermediate transfer belt 11 and moves around the intermediate transfer belt 11 and faces the intermediate transfer belt 11. It has an intermediate transfer belt cleaning device 13 which is arranged and cleans the intermediate transfer belt 11.
The optical writing device 8 is arranged below the four image stations so as to face them.

The optical writing device 8 is equipped with a semiconductor laser as a light source, a coupling lens, an fθ lens, a toroidal lens, a folding mirror, a rotating multifaceted mirror as a polarizing means, and the like. The optical writing device 8 emits writing light Lb corresponding to each color for each of the photoconductor drums 20Y, 20C, 20M, and 20Bk, and forms an electrostatic latent image on each photoconductor drum 20.
In FIG. 1, for convenience, a reference numeral Lb is attached to the writing light only for the image station of the black image, but the same applies to other image stations.

At the lower part of the image forming apparatus 100, a sheet feeding device 61 as a paper feed cassette loaded with the paper S to be conveyed between the photoconductor drum 20 and the intermediate transfer belt 11 is provided. The sheet feeding device 61 has a feeding roller 3 that abuts on the upper surface of the uppermost paper S, and the feeding roller 3 is rotationally driven in the counterclockwise direction to feed the uppermost paper S. It is fed toward the resist roller vs. 4.
The paper S conveyed from the sheet feeding device 61 by driving the feeding roller 3 is rotated and driven at a predetermined timing in accordance with the formation timing of the toner image by the image station, and the intermediate transfer belts 11 and 2 are driven by the resist roller pair 4. It is fed toward the secondary transfer unit between the secondary transfer roller 5 and the secondary transfer roller 5. The sensor detects that the tip of the paper S has reached the resist roller pair 4.

The paper S on which the toner image is transferred is sent to the fixing device 200, where heat and pressure are applied to fix the toner image. The fixed paper S is ejected and loaded on the output tray 17 formed on the upper surface of the image forming apparatus main body by the output roller pair 7.
Below the output tray 17, toner bottles 9Y, 9C, 9M, and 9Bk filled with toners of yellow, cyan, magenta, and black are provided.

The intermediate transfer belt unit 10 has a drive roller 72 and a driven roller 73 around which the intermediate transfer belt 11 is hung, in addition to the intermediate transfer belt 11, the primary transfer rollers 12Y, 12C, 12M, and 12Bk. The driven roller 73 also has a function as a tension urging means for the intermediate transfer belt 11. Therefore, the driven roller 73 is provided with a urging means using a spring or the like. The transfer device 71 is composed of the intermediate transfer belt unit 10, the primary transfer rollers 12Y, 12C, 12M, 12Bk, the secondary transfer roller 5, and the intermediate transfer belt cleaning device 13.

The intermediate transfer belt cleaning device 13 provided in the transfer device 71 has a cleaning brush and a cleaning blade arranged so as to face and abut against the intermediate transfer belt 11. The intermediate transfer belt cleaning device 13 scrapes off foreign matter such as residual toner on the intermediate transfer belt 11 with the cleaning brush and the cleaning blade. The intermediate transfer belt cleaning device 13 also has a discharging means for carrying out and discarding the residual toner removed from the intermediate transfer belt 11.

The configuration and operation of the fixing device 200 to which the present invention can be applied will be described with reference to FIG. FIG. 2 is a cross-sectional view of a fixing device to which the present invention can be applied. In FIG. 2, Z is a vertical or vertical direction, Y is a device or member orthogonal to the vertical direction Z, a longitudinal direction or an axial direction, and X is a device orthogonal to the vertical direction Z and orthogonal to the longitudinal direction Y. And the width direction of the member, respectively.
As shown in FIG. 2, the fixing device 200 includes a fixing belt 201 as a thin and flexible endless fixing member, and an opposing member arranged so as to face the fixing belt 201 outside the fixing belt 201. It has a pressure roller 203 as a pressure member. The fixing belt 201 is formed in a tubular shape or a cylindrical shape, and a plurality of halogen heaters 202A and 202B as main fixing heat sources are arranged inside the fixing belt 201. The fixing belt 201 is directly heated from the inner peripheral side thereof by the radiant heat of the halogen heaters 202A and 202B.

Inside the fixing belt 201, a nip forming member 206 for forming a nip portion N for sandwiching and transporting the paper S between the fixing belt 201 and the pressure roller 203 is provided. The surface of the nip forming member 206 on the N side of the nip portion is covered with the heat transfer assisting member 216. The nip forming member 206 is a heat-resistant member having high mechanical strength and a heat-resistant temperature of 200 ° C. or higher, particularly a heat-resistant resin such as a polyimide (PI) resin or a polyetheretherketone (PEEK) resin, which is reinforced with glass fiber. It is composed of. As a result, deformation of the nip forming member 206 due to heat is prevented in the toner fixing temperature range, a stable fixing nip state is ensured, and the output image quality is stabilized.
The nip forming member 206 indirectly slides on the inner surface of the fixing belt 201 (hereinafter, also simply referred to as “belt inner surface”) via the heat transfer assisting member 216. The toner image transferred onto the paper S is fixed by heat and pressure at the nip portion N. In FIG. 2, Na indicates the inlet side of the nip portion N, and Nb indicates the outlet side of the nip portion N. Hereinafter, the inlet side Na of the nip portion N is also simply referred to as a nip inlet side Na, and the outlet side of the nip portion N is also simply referred to as a nip outlet side Nb.

In FIG. 2, the shape of the heat transfer assisting member 216 is flat, but the shape of the heat transfer assisting member 216 may be concave or other. When the heat transfer assisting member 216 has a concave shape, the discharge direction of the tip of the paper S, which is also the transport direction of the paper S indicated by the arrow in FIG. 2, is closer to the pressurizing roller 203, which improves the separability and transports the paper, etc. The occurrence of jam is suppressed.
Further, inside the fixing belt 201, end heaters 226a and 226b as end heat sources provided integrally with the nip forming member 206 at both ends of the fixing belt 201 in the nip forming member 206 in the longitudinal direction Y. A stay member 207 that holds the nip forming member 206 against the pressing force from the pressurizing roller 203 is arranged. As the end heaters 226a and 226b, a contact electric heat type heat source which is a resistance heating element such as a ceramic heater is used.

The nip forming member 206, the heat transfer assisting member 216, and the stay member 207 all have a length extending in the longitudinal direction.
The heat transfer assisting member 216 prevents the heat of the end heaters 226a and 226b from staying locally, and actively diffuses and moves the heat to reduce the temperature non-uniformity due to the heating of the end heaters 226a and 226b. It is provided for this purpose. Therefore, it is desirable that the heat transfer assisting member 216 is a material capable of heat transfer in a short time, and it is desirable that the member is a member such as copper, aluminum, or silver having high thermal conductivity. Considering cost, availability, thermal conductivity characteristics, and workability comprehensively, it is most desirable to use copper.
In the fixing device 200, the surface of the heat transfer assisting member 216 facing the inner surface of the fixing belt 201 is a nip forming surface that directly contacts the fixing belt 201. Therefore, a lubricant such as fluorine grease or silicone oil for reducing the sliding torque is supplied between the heat transfer assisting member 216 and the inner surface (belt inner surface) of the fixing belt 201.
As shown in FIG. 2, a temperature sensor as a temperature detecting means for detecting the temperature of the fixing belt 201 is located at an appropriate position on the outer peripheral side of the fixing belt 201, for example, on the upstream side in the rotation direction of the fixing belt 201 at the nip portion N. 213 is provided. Further, on the downstream side (nip portion outlet side) of the nip portion N in the paper transport direction, a separating member 214 for separating the paper P from the fixing belt 201 is provided.

Inside the fixing belt 201, a nip forming member 206 and a stay member 207 as a support member for supporting the nip portion N are provided. As a result, the nip forming member 206 that receives pressure from the pressurizing roller 203 is prevented from bending, and a uniform nip width can be obtained in the longitudinal direction. The stay member 207 is composed of a pair of stay members 207A and 207B having a substantially L-shaped cross section. Both ends of the stay members 207A and 207B are held and fixed to a flange member as a holding member, and are positioned.

The stay member 207A includes an upright portion 207c that stands up on the side opposite to the nip portion N side, and a vertical portion 207d that extends upward from the upright portion 207c in the vertical direction Z. Similarly, the stay member 207B includes a 207e whose side opposite to the nip portion N side stands up and a vertical portion 207f extending downward from the upright portion 207e in the vertical direction Z. The stay members 207A and 207B have a T-shaped cross section in a state where the standing portions 207c and 207e are in contact with each other.
The stay members 207A and 207B are arranged in a state of partitioning the above-mentioned halogen heaters 202A and 202B with the upright portions 207c and 207e separated from each other. By arranging the halogen heaters 202A and 202B in the upper and lower separate regions sandwiching the stay members 207A and 207B in this way, the fixing belt 201 is directly heated by the halogen heaters 202A and 202B from the inner surface side by radiant heat. Further, since the halogen heaters 202A and 202B are not surrounded by the stay members 207A and 207B (the centers of the halogen heaters 202A and 202B are outside the space surrounded by the stay members 207A and 207B), the irradiation angles α and β are set. The angle becomes obtuse, and the heating efficiency can be improved.

Further, in order to improve the heating efficiency by the halogen heaters 202A and 202B, a thin plate-shaped reflective member 209 is provided between the halogen heaters 202A and 202B and the stay members 207A and 207B, respectively. As a result, wasteful energy consumption due to the stay members 207A and 207B being heated by radiant heat such as infrared rays from the halogen heaters 202A and 202B is suppressed. Here, the same effect can be obtained by performing heat insulation or mirror surface treatment on the surfaces of the stay members 207A and 207B instead of providing the reflective member 209.

The pressure roller 203 has a structure in which the elastic rubber layer 204 is provided on the core metal 205. On the surface of the elastic rubber layer 204, a mold release layer made of PFA or PTFE is provided with a predetermined layer thickness (for example, 5 to 50 μm) in order to obtain mold releasability.
The pressurizing roller 203 rotates by transmitting a driving force from a driving source such as a motor provided in the image forming apparatus 100 via a driving force transmitting means such as a gear or a belt. Further, the pressure roller 203 is pressed against the fixing belt 201 side by a urging means such as a spring, and the elastic rubber layer 204 of the pressure roller 203 is crushed and elastically deformed, so that the paper S is conveyed in the transport direction. A predetermined nip width is formed in.

The pressurizing roller 203 may be a solid roller, but it is preferably hollow because the heat capacity is reduced, and a heating source such as a halogen heater may be provided inside.
The elastic rubber layer 204 may be solid rubber, but sponge rubber may be used when there is no heater inside the pressure roller. Sponge rubber is more preferable than solid rubber because it has higher heat insulating properties and is less likely to take away heat from the fixing belt 201.

The fixing belt 201 is made of a metal belt such as nickel or stainless steel (SUS) having a layer thickness of about 30 to 50 μm, an endless belt using a resin material such as polyimide, or a film. The surface layer of the fixing belt 201 has a release layer such as a PFA or PTFE layer, and has a release property so that toner does not adhere. In addition, an elastic layer formed of a silicone rubber layer or the like may be provided between the base material of the belt and the PFA or PTFE layer.
If there is no silicone rubber layer, the heat capacity will be smaller and the fixability will be improved, but when the unfixed image is crushed and fixed, the subtle irregularities on the belt surface will be transferred to the image, and the solid part of the image will be Yuzu (Yuzu). Yuzu) There is a problem that uneven skin-like luster (Yuzu skin image) remains. In order to improve this, it is necessary to provide a silicone rubber layer of 100 μm or more. With this configuration, the silicone rubber layer is deformed, minute irregularities are absorbed, and the Yuzu skin image and fixing unevenness are improved.

The fixing belt 201 is rotationally driven by the drive source of the pressurizing roller 203, so that the fixing belt 201 is rotated and driven by contact friction with the pressurizing roller 203. The fixing belt 201 is sandwiched between the pressurizing roller 203 and the heat transfer assisting member 216 at the nip portion N and rotates, but the fixing belt 201 remains cylindrical except for the nip portion N and is guided by the flange members arranged at both ends.・ It is supported. As a result, the fixing belt 201 can travel while being stably maintained in a cylindrical shape.
With the above configuration, it is possible to realize an inexpensive fixing device 200 that warms up quickly.

The problems and problems of the above-mentioned conventional examples of the nip forming member and the heat transfer assisting member of the fixing device will be described with reference to FIG. FIG. 3 is an exploded perspective view showing a specific configuration of a nip forming member and a heat transfer assisting member of a fixing device to which the present invention is applied.
As shown in FIG. 3, the surface of the nip forming member 206 opposite to the fixing belt 201 (see FIG. 2) is the side surface of the upright portions 207c and 207e which are the side surfaces of the stay members 207A and 207B on the pressure roller 203 side. They come into contact, are fixed via appropriate fastening means, and are substantially integrated. At this time, the boss and the pin may be provided with shapes such as a combination and fixed so that they are substantially integrated.
The heat transfer assisting member 216 is fitted and integrated so as to cover the surface of the rectangular parallelepiped nip forming member 206 facing the inner surface of the fixing belt 201. The heat transfer assisting member 216 and the nip forming member 206 may be integrally formed by providing a claw or the like and engaging with each other, but a means such as adhesion may be used.

Recesses 206a and 206b as stepped portions are formed at both ends of the nip forming member 206 in the longitudinal direction. End heaters 226a and 226b as end heat sources are housed and fixed in these recesses 206a and 206b.
The surface of the heat transfer assisting member 216 facing the pressure roller 203 (see FIG. 2) is formed as a nip forming surface 216a, but due to mechanical strength, the nip forming surface is substantially the nip forming surface. The surface 206c facing the pressurizing roller 203 of 206.

The cross-sectional shape of the heat transfer assisting member 216 is a concave shape with an opening facing left sideways, and the inlet side Na of the nip portions N at both ends in the longitudinal direction (hereinafter, also simply referred to as the nip inlet side Na) and the nip portion N. The exit side Nb (hereinafter, also simply referred to as the nip outlet side Nb) has a corner portion 216b surrounded by a broken line. The point contact portion between the corner portion 216b and the inner surface (belt inner surface) of the fixing belt 201 applies a high load to the belt inner surface, causing scraping, kinking, or breakage of the belt inner surface. Further, not only both ends of the heat transfer assisting member 216 in the longitudinal direction but also the bent portions 216c on the nip portion inlet side and the nip portion outlet side of the heat transfer assisting member 216 have a steep shape with respect to the inner surface of the belt. Line contact occurs, and this line contact portion similarly applies a high load to the inner surface of the belt, causing scraping, kinking, and breakage of the inner surface of the belt.

Further, in the configuration of FIG. 3, the heat transfer assisting member 216 is fitted and integrated with the nip forming member 206, but the heat transfer assisting member 216 is absent, and the nip forming member 206 and the fixing belt 201 are directly rubbed. Even in this configuration, the corners and bends of the nip forming member 206 also cause scraping, kinking, and breakage of the inner surface of the belt. An example of such a fixing device will be described with reference to FIG. 7 described later.
In order to prevent the inner surface of the belt from being scraped, kinked, or damaged by the bent portions of the nip inlet side Na and nip outlet side Nb of the heat transfer assisting member 216, and the corner portions at both ends thereof, the bent portions and corner portions are shaped. It is necessary to change the load to reduce the load on the inner surface of the belt, and to eliminate the rubbing state between the line or point contact area of the bent portion or the corner portion and the inner surface of the belt.

(Embodiment)
Therefore, an embodiment capable of solving the problems of the conventional fixing device shown in FIG. 3 and the problems of the background technology will be described. In the fixing device according to the embodiment of the present invention, the heat transfer assisting member (or nip forming member) is a region in contact with the inner surface of the fixing member, and is at least one of the upstream side and the downstream side in the rotational direction of the fixing member. A feature is that a rotating member that follows the rotation of the fixing member is provided at one location on the upstream side. Hereinafter, specific examples of the above-described embodiment will be described.

(Example 1)
The fixing device 200A according to the first embodiment will be described with reference to FIG. FIG. 4A is a view showing a configuration around a nip portion of the fixing device according to the first embodiment, and is a front view and a view showing a configuration in which rotating members are provided on the nip inlet side and the nip outlet side of the nip forming member. 4 (b) is a perspective view of FIG. 4 (a).
As shown in FIG. 4, the fixing device 200A according to the first embodiment has a nip inlet of the heat transfer assisting member 216 fitted to the nip forming member 206 as compared with the fixing device 200 shown in FIGS. 2 and 3. The main difference is that the rotating member 219 is provided on the side Na, and the rotating member 217 is provided on the nip outlet side Nb of the heat transfer assisting member 216 fitted to the nip forming member 206.

The heat transfer assisting member 216 and the nip forming member 206 are formed by being cut out so that the arrangement portions of the rotating members 217 and 219 do not interfere with the rotating members 217 and 219.
Each of the rotating members 217 and 219 has a cylindrical shape extending over the entire area in the longitudinal direction Y at the nip outlet side Nb and the nip inlet side Na of the heat transfer assisting member 216. Further, each of the rotating members 217 and 219 has a cylindrical outer peripheral surface and a bent portion on the nip outlet side and corner portions at both ends (these portions are actually actually formed) formed on the heat transfer assisting member. It is formed in a shape of an appropriate size so as to cover (it does not exist because it is cut out as described above). Further, in view of the above-mentioned functions of the heat transfer assisting member 216, in FIG. 4A, the amount of protrusion of the heat transfer assisting member 216 on the outer peripheral surface of each of the rotating members 217 and 219 from the right surface is set to an appropriate range. Of course.
The rotating member 217 is press-fitted into the rotating shaft 218, and the rotating member 219 is press-fitted into the rotating shaft 220 to be integrated. Both ends of the rotating shafts 218 and 220 in the longitudinal direction Y are rotatably supported by bearings arranged at both ends of the nip forming member 206 in the longitudinal direction Y. As described above, each of the rotating members 217 and 219 is configured to follow the rotation of the fixing belt 201.

The means for rotatably supporting both ends of the rotating shafts 218 and 220 in the longitudinal direction Y is not limited to the configuration supported by the bearings arranged on the nip forming member 206 as described above, and the nip forming member. The 206 may be supported via bearings by fixing members such as side plates appropriately provided on the outside of both ends.
Further, when the first embodiment of the present invention is applied to the fixing device 200 of FIG. 2, each of the rotating members 217 and 219 provided on the heat transfer assisting member 216 is in the pressurizing operation state of the pressurizing roller 203 shown in FIG. It goes without saying that sometimes, by setting an appropriate arrangement position and shape so as not to interfere with the pressure roller 203, a device is made so that the rotating members 217 and 219 are not damaged (Example 2 described later). And so on).

In the first embodiment, as the fixing belt 201 (see FIG. 2) rotates, the rotating member 219 of the nip inlet side Na of the heat transfer assisting member 216 and the rotating member 217 of the nip outlet side Nb of the heat transfer assisting member 216 are driven. Take around. Therefore, the contact regions on the upstream side and the downstream side in the fixing belt rotation direction of the heat transfer assisting member 216 do not rub against the inner surface of the fixing belt 201 in a high load state.
Therefore, according to the first embodiment, the contact regions on the upstream side and the downstream side in the fixing belt rotation direction of the heat transfer assisting member 216 do not rub against the inner surface of the fixing belt with a high load. As a result, it is possible to prevent the inner surface of the fixing belt from being scraped, the fixing belt from being kinked, and the fixing belt from being damaged, thereby improving the durability of the fixing belt.

(Example 2)
The fixing device 200B according to the second embodiment will be described with reference to FIG. FIG. 5 is a diagram showing a configuration around a nip portion of the fixing device according to the second embodiment, in which both ends in the longitudinal direction on the inlet side of the heat transfer assisting member and a plurality of truncated cone-shaped rotating members in between. It is a perspective view which shows the structure with.
Compared with the fixing device 200A shown in FIG. 4, the fixing device 200B according to the second embodiment shown in FIG. 5 is located only on the nip inlet side Na of the heat transfer assisting member 216 fitted to the nip forming member 206. The main difference is that a plurality of rotating members 221 are provided partially or intermittently instead of the entire area in the longitudinal direction Y.

Each rotating member 221 is press-fitted into a common rotating shaft 222 and integrated. Both ends of the rotating shaft 222 in the longitudinal direction Y are rotatably supported by bearings arranged at both ends of the nip forming member 206 in the longitudinal direction Y. As described above, each of the plurality of rotating members 221 is configured to follow the rotation of the fixing belt 201.

When the fixing belt rotates, it is pulled into the nip inlet, so that it hits the corner portion and the bent portion on the nip inlet side of the heat transfer assisting member 216 most strongly. Further, it is difficult to freely determine the shape of the bent portion on the nip outlet side because it greatly affects the separability of the paper.
Therefore, the most practical configuration is that the rotating member is provided only on the nip inlet side. Further, since the fixing belt is made of a metal base material such as nickel or stainless steel (SUS) and has sufficient rigidity, it is not necessary to provide a rotating member through the entire area in the longitudinal direction Y, and the highest load is applied to the inner surface of the belt. By providing the rotating members 221 at predetermined intervals between both ends of the heat transfer assisting member 216, contact with the corners and bent portions on the nip inlet side of the heat transfer assisting member 216 can be avoided.

Further, when the rotating member 221 is partially provided in the longitudinal direction Y, the notch 216a may be opened only at the corresponding portion of the heat transfer assisting member 216, and the heat transfer assisting member 216 or the nip forming member 206 may be integrated. Will be able to be designed as.
Further, the rotating member 221 is formed in a truncated cone shape in which the diameter thereof increases from the center of the longitudinal direction Y toward the end side. The rotating member 221 is not limited to this truncated cone shape, and may have a double truncated cone shape.

As described above, in the second embodiment, the fixing belt passes over the rotating member 221 whose diameter gradually changes in the longitudinal direction Y, so that a conveying force is generated to the center or the outside with respect to the fixing belt, and the component. It is also possible to prevent the fixing belt from shifting due to variations in the fixing belt. According to the second embodiment, the contact region on the upstream side of the heat transfer assisting member 216 in the rotation direction of the fixing belt does not rub against the inner surface of the fixing belt with a high load. As a result, it is possible to prevent the inner surface of the fixing belt from being scraped, the fixing belt from being kinked, and the fixing belt from being damaged, thereby improving the durability of the fixing belt.

(Modified Example of Example 2)
A modified example of the second embodiment will be described with reference to FIG. FIG. 6A is a perspective view showing the rotating member according to the second embodiment, and FIG. 6B is a perspective view showing the rotating member according to the modified example of the second embodiment.
The rotating member 223 according to the modified example shown in FIG. 6B has both ends formed in an R curved surface shape in the longitudinal direction Y as compared with the rotating member 221 according to the second embodiment shown in FIG. 6A. The main difference is that.

As shown in FIG. 6A, the truncated cone-shaped rotating member 221 has sharp edges at both ends 221a and 221b in the longitudinal direction Y, and it can be said that the rotating member 221 does not rub against the inner surface of the fixing belt. A high load is applied to the inner surface of the belt. On the other hand, the rotating member 223 reduces the load on the fixing belt by making both end portions 223a and 223b in the longitudinal direction Y curved surfaces and eliminating edges. When the calorific value of the fixing belt is further reduced, such as to ensure energy saving, the base material of the fixing belt becomes thin, which is disadvantageous in durability. Therefore, the fixing belt is fixed even in a non-rubbing / non-sliding state. It is necessary to reduce the load on the belt, and it is desirable to have an R curved surface shape such as the rotating member 223.

With reference to FIG. 7, a fixing device not provided with an end heater and a heat transfer assisting member to which the present invention can be applied will be described. FIG. 7 is a cross-sectional view of a fixing device not provided with an end heater and a heat transfer assisting member to which the present invention can be applied.
The nip forming member provided with the rotating member according to the above-described embodiment and each embodiment can be applied not only to a fixing device provided with an end heater in the nip forming member, but also of course, an end heater and heat transfer assistance. It can also be applied to a known fixing device that does not have a member.

The fixing device 80 to which the present invention shown in FIG. 7 can be applied is a fixing device that has already been known. Compared with the fixing device 200 provided with the end heaters 226a and 226b on the nip forming member 206 shown in FIG. 2, the fixing device 80 is basically different only in the presence / absence of the end heater and the number of main heat sources. Therefore, by assigning a reference code to each member, detailed description thereof will be omitted.

That is, the fixing device 80 of FIG. 7 uses the fixing belt 21 instead of the fixing belt 201 and the pressure roller 22 instead of the pressure roller 203 as compared with the fixing device 200 of FIG. , A point where the nip forming member 24 is used instead of the nip forming member 206, a point where a single halogen heater 23 is used instead of the halogen heaters 202A and 202B, and end heaters 226a and 226b and a heat transfer assisting member 216 are provided. The difference is that it is not. Further, the difference is that the stay 25 is used instead of the stay members 207A and 208B, the reflective member 28 is used instead of the reflective member 209, and the sliding member 27 is used.
Further, the fixing device 80 of FIG. 7 has a temperature sensor 29 as a temperature detecting means for detecting the temperature of the fixing belt 21, and a separating member 40 for separating the paper P from the fixing belt 21.

Even in the fixing device not provided with the end heater and the heat transfer assisting member as shown in FIG. 7, the embodiment is based on the contents described in the above-described embodiments, Examples 1 and 2, and the modified examples of the second embodiment. And examples are configured to obtain the same effect as described above. That is, the rotating members 217, 219, 221 or 223 described in the first and second embodiments and the modified examples of the second embodiment are the regions where the nip forming member 24 comes into contact with the inner surface of the fixing belt 21, and the fixing belt 21 It may be provided in an appropriate form at at least one of the upstream side and the downstream side in the rotation direction of the above.

As described above, it can be said that the following first to ninth aspects are substantially described in the above-described embodiments, Examples 1, 2 and the like.
The first aspect is a flexible and rotatable endless fixing member, an opposing member arranged outside the fixing member and facing the fixing member, a paper passing region in the longitudinal direction of the fixing member, and the like. A fixing heat source that heats at least the central portion of the recording medium sandwiching region, and a nip forming member that is provided inside the fixing member and forms a nip portion that sandwiches and conveys the recording medium between the fixing member and the facing member. Is a region where the nip forming member comes into contact with the inner surface of the fixing member, and is provided at least one of the upstream side and the downstream side in the rotation direction of the fixing member, and is driven by the rotation of the fixing member. It is a fixing device provided with a rotating member.

According to the first aspect, the rotation provided in at least one of the upstream side and the downstream side in the rotation direction of the fixing member in the region where the nip forming member contacts the inner surface of the fixing member. The member is driven by the rotation of the fixing member. Therefore, the nip forming member does not rub against the inner surface of the fixing member with a high load. As a result, it is possible to prevent the fixing member from being scraped, kinked, or damaged, and thus the durability of the fixing member can be improved.

A second aspect is a fixing member such as a flexible and rotatable endless fixing belt 201, and an opposing member such as a pressure roller 203 arranged outside the fixing member and facing the fixing member. A fixing heat source such as halogen heaters 202A and 202B that heat at least the central portion of a recording medium holding area such as a paper passing area in the longitudinal direction such as the longitudinal direction Y of the fixing member, and a fixing heat source provided inside the fixing member and facing the fixing member. A nip forming member 206 for forming a nip portion such as a nip portion N for sandwiching and transporting a recording medium such as paper S between the member and an inner surface of an end portion provided on the nip forming member in the longitudinal direction of the fixing member. An end heat source such as the end heaters 226a and 226b that heats the heat transfer assisting member 216 that comes into contact with the inner surface and the end heat source of the fixing member and transfers the heat of the end heat source in the longitudinal direction of the fixing member. A region where the heat transfer assisting member and the heat transfer assisting member come into contact with the inner surface of the fixing member, which is provided at least one of the upstream side and the downstream side in the rotation direction of the fixing member, and is provided on the fixing member. It is a fixing device including a rotating member such as a rotating member 217, 219, 221 or 223 that follows the rotation.

According to the second aspect, the heat transfer assisting member is provided at least one of the upstream side and the downstream side in the rotation direction of the fixing member in the region where the heat transfer assisting member comes into contact with the inner surface of the fixing member. The rotating member follows the rotation of the fixing member. Therefore, the heat transfer assisting member does not rub against the inner surface of the fixing member with a high load. As a result, it is possible to prevent the fixing member from being scraped, kinked, or damaged, and thus the durability of the fixing member can be improved. In addition, the rise in the temperature at the end of the fixing member is suppressed, which can contribute to the improvement of productivity.

In the third aspect, in the first or second aspect, the rotating members such as the rotating members 217 and 219 are provided over the entire longitudinal direction of the nip forming member or the heat transfer assisting member.
According to the third aspect, the same effect as that of the first aspect or the second aspect is obtained.

In the fourth aspect, in the first or second aspect, the rotating members such as the rotating members 217, 219, 221 or 223 are provided at least at both ends in the longitudinal direction of the nip forming member or the heat transfer assisting member. There is.
According to the fourth aspect, the same effect as that of the first aspect or the second aspect is obtained.

In a fifth aspect, in the fourth aspect, the rotating member such as the rotating member 217, 219, 221 or 223 is at least between both ends in the longitudinal direction of the nip forming member or the heat transfer assisting member. There is one place.

In the sixth aspect, in any one of the first to fifth aspects, the rotating members such as the rotating members 217 and 219 have a cylindrical shape.

In the seventh aspect, in any one of the first to fifth aspects, the rotating members such as the rotating members 221 and 223 have a truncated cone shape or a bicone trapezoidal shape.
According to the seventh aspect, in addition to the same effect as that of the first aspect or the second aspect, the effect of preventing the fixing member from leaning is also obtained.

In the eighth aspect, in the seventh aspect, the rotating member such as the rotating member 223 has an R curved surface shape at the end in the longitudinal direction.
According to the eighth aspect, in addition to the same effect as the effect of the first aspect or the second aspect, the load on the fixing member can be further reduced.

A ninth aspect is an image forming apparatus having the fixing device of the first to eighth aspects.
According to the ninth aspect, it is possible to provide an image forming apparatus that exerts the effect of the fixing apparatus of the first to eighth aspects.

Although the explanations are mixed up, I will supplement the techniques prior to Patent Document 1 described in the background techniques above.
First, Japanese Patent No. 2861280 can be mentioned. In this patent gazette, surf fixing using a ceramic heater is proposed. This method makes it possible to reduce the heat capacity and size compared to the belt type fixing device, but since only the nip part is locally heated, the other parts are not heated and the belt is the coldest at the entrance of the nip part. There is a problem that the fixing failure is likely to occur. In particular, in a high-speed machine, there is a problem that the belt rotates quickly and the heat dissipation of the belt other than the nip portion increases, so that the fixing failure is more likely to occur.

Next, Japanese Patent No. 4818826 can be mentioned. In this patent gazette, it is possible to heat the entire endless belt, shorten the first print time, eliminate the lack of heat during high-speed rotation, and have good fixability even when mounted in a high-production image forming apparatus. A fixing device that can obtain the above has been proposed. In the fixing device shown in FIG. 1 of this patent publication, a pipe-shaped metal heat conductor 2 is fixed inside the endless belt 1 so as to be able to guide the movement of the endless belt 1, and inside the metal heat conductor 2. The endless belt 1 is heated by the heat source 3 via the metal heat conductor 2. Further, a pressure roller 4 is provided which is in contact with the metal thermal conductor 2 via the endless belt 1 to form a nip portion N, and the endless belt 1 is moved in the circumferential direction so as to rotate along with the rotation of the pressure roller 4. Let me. With this configuration, it is possible to heat the entire endless belt that constitutes the fixing device, shorten the first print time from the standby for heating, and eliminate the lack of heat during high-speed rotation. There is.
However, in order to further improve energy saving and first print time, it is necessary to further improve the thermal efficiency, and since the endless belt is indirectly heated via the metal heat conductor, the endless belt is indirectly heated without using the metal heat conductor. A configuration has been devised that directly heats the endless belt. In this configuration, the heat transfer efficiency can be significantly improved, the power consumption can be reduced, and the first print time can be further shortened. In addition, since there is no metal thermal conductor, cost reduction is possible.

Although the preferred embodiment of the present invention has been described above, the present invention is not limited to such a specific embodiment, and the present invention described in the claims unless otherwise specified in the above description. Various modifications and changes are possible within the scope of the above. For example, the technical items described in the above-described embodiments and examples may be appropriately combined.

For example, a combination of Example 1 shown in FIG. 4, Example 2 shown in FIG. 5, and a modified example of Example 2 shown in FIG. 6 (b) may be appropriately combined. For example, instead of the truncated cone-shaped rotating member 221 shown in FIG. 5, the cylindrical rotating member 219 shown in FIG. 4 is intermittently formed in the longitudinal direction Y of the fixing member to form the heat transfer assisting member 216 or The nip forming member 206 may be provided at the above-mentioned location in an appropriate manner.
Further, the truncated cone-shaped rotating member 221 shown in FIG. 5 and the rotating member 223 shown in FIG. 6B are in a region where the heat transfer assisting member 216 or the nip forming member 206 comes into contact with the inner surface of the fixing member. , May be provided in an appropriate manner on the downstream side of the fixing member in the rotation direction.

In the above-described embodiments and examples, paper S is shown as a recording medium on which an image is formed, but the recording medium is not limited to recording paper such as paper S, and is thick paper, postcards, envelopes, and ordinary paper. Includes paper, thin paper, coated paper (coated paper, art paper, etc.), tracing paper, etc. Further, as a recording medium other than paper, any medium such as an OHP sheet, an OHP film, and a resin film may be used as long as it has a sheet shape and can form an image.

The effects appropriately described in the embodiments of the present invention merely list the most preferable effects arising from the present invention, and the effects according to the present invention are limited to those described in the embodiments of the present invention. It's not a thing.

100 Image forming device 200A, 200B Fixing device 201 Fixing belt (example of fixing member)
202A, 202B halogen heater (an example of fixing heat source)
203 Pressurized roller (an example of facing member)
206 Nip forming member 216 Heat transfer assisting member 217, 219, 211,223 Rotating members 226a, 226b End heater (example of end heat source)
N Nip part Na Nip inlet side (upstream side in the rotation direction of the fixing member in the nip part)
Nb Nip outlet side (downstream side in the rotation direction of the fixing member in the nip part)
S paper (an example of recording medium)
X Width direction Y Longitudinal direction Z Vertical / vertical direction

Japanese Unexamined Patent Publication No. 2016-145961

Claims (8)

Flexible and rotatable endless fixing member,
An opposing member that is arranged outside the fixing member and faces the fixing member,
A fixing heat source that heats at least the central portion of the recording medium sandwiching region in the longitudinal direction of the fixing member,
A nip forming member provided inside the fixing member and forming a nip portion for sandwiching a recording medium between the fixing member and the facing member.
A region where the nip forming member comes into contact with the inner surface of the fixing member, and is provided at at least one of the upstream side and the downstream side in the rotation direction of the fixing member, and is driven by the rotation of the fixing member. A fixing device comprising a rotating member to be provided, wherein the rotating member has a truncated cone shape or a double truncated cone shape. Flexible and rotatable endless fixing member,
An opposing member that is arranged outside the fixing member and faces the fixing member,
A fixing heat source that heats at least the central portion of the recording medium sandwiching region in the longitudinal direction of the fixing member,
A nip forming member provided inside the fixing member and forming a nip portion for sandwiching a recording medium between the fixing member and the facing member.
An end heat source provided on the nip forming member and heating an end portion of the fixing member in the longitudinal direction,
A heat transfer assisting member that comes into contact with the inner surface of the fixing member and the end heat source and transfers heat of the end heat source in the longitudinal direction of the fixing member.
A region where the heat transfer assisting member comes into contact with the inner surface of the fixing member, and is provided at least one of the upstream side and the downstream side in the rotation direction of the fixing member, and is provided for rotation of the fixing member. A fixing device including a driven rotating member. The fixing device according to claim 1 or 2, wherein the rotating member is provided over the entire area of the nip forming member or the heat transfer assisting member in the longitudinal direction. The fixing device according to claim 1 or 2, wherein the rotating member is provided at least at both ends of the nip forming member or the heat transfer assisting member in the longitudinal direction. The fixing device according to claim 4, wherein the rotating member is provided at least at one position between both ends of the nip forming member or the heat transfer assisting member in the longitudinal direction. The fixing device according to claim 2 , wherein the rotating member has a cylindrical shape. The fixing device according to claim 6, wherein the rotating member has an R curved surface shape at an end portion in the longitudinal direction. An image forming apparatus having the fixing apparatus according to any one of claims 1 to 7.

Images