JP2005158639A - Fixing device and image forming device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To contrive further prolongation of the life of a fixing device by preventing generation of a crack at the end part of a fixing sleeve due to scrub between a fixing flange and itself. <P>SOLUTION: The heat fixing device 20 is composed of a fixing sleeve 21; a heater holder 23 guiding the fixing sleeve 21; a pressure roller 24 forming a nip part N pinching and transporting a recorded material against the heater holder 23 through the fixing sleeve 21; and a heater 22 heating the recorded material transported through the inside of the nip part N, controlled so as to contact the inner face of the fixing sleeve 21 and maintain a set temperature. The fixing sleeve 21 is formed by forming a silicon rubber part 21a at least on a SUS belt part 21b, and the silicon rubber part 21a is made to protrude further than the SUS belt part 21b in an axial direction at least at one end part out of the end parts of the fixing sleeve 21 in the axial direction. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a heating device that sandwiches and conveys a recording material at a nip formed between a film-like rotating member guided by a guide member and a backup member, and heats the recording material. The present invention relates to an image forming apparatus provided as a heat fixing device for heat fixing.

  In an image forming apparatus such as an electrophotographic copying machine or a printer, an unfixed toner image formed or supported directly or on a recording material such as plain paper by a suitable image forming process means such as an electrophotographic process is used as a recording material. Conventionally, a heat roller type heat fixing device has been widely used as a fixing device for heat fixing as a permanently fixed image on the surface.

  In recent years, a film heating type fixing device has been put into practical use from the viewpoint of quick start and energy saving. For example, as described in JP-A-2002-231419 and JP-A-2002-323821, a fixing device using a metal film such as SUS or nickel as a fixing film (film-like rotating body) is known. Has proposed a fixing device using a metal film provided with an elastic layer.

  In the fixing device using this metal thin film (hereinafter referred to as a fixing sleeve), the fixing sleeve is repeatedly rotated and used, and therefore, the fixing sleeve end is cracked, leading to a problem. was there. Although the fixing sleeve itself has high rigidity, in the fixing sleeve manufacturing process, when the fixing sleeve is cut to an appropriate length for the fixing device, burrs and minute cracks are generated at the end of the fixing sleeve. When rubbing, the above-mentioned cracks occurred starting from such burrs and cracks.

  In order to prevent such cracks at the end of the fixing sleeve, Japanese Patent Application Laid-Open No. 2002-231419 has a structure in which a fixing flange that supports the end of the fixing sleeve is supported from the outer peripheral surface of the fixing sleeve and rotates together with the fixing sleeve. Thus, a configuration for preventing the rubbing between the fixing sleeve end and the fixing device is disclosed.

JP 2002-231419 A JP 2002-323821 A

  However, in the above conventional example, the fixing flange is not positively applied with a rotational driving force by using a driving means such as a motor, and the fixing flange is used together with the fixing sleeve by a frictional force at a contact portion with the rotating fixing sleeve. Due to the rotating configuration, if the sliding resistance of the portion that supports the fixing flange rotatably is large, the fixing flange does not rotate with the fixing sleeve, and the end surface of the fixing sleeve may rub against the fixing flange. there were.

  For example, when the pressure balance in the axial direction (longitudinal direction) of the pressure roller that contacts the fixing sleeve and forms the nip portion is not uniform, a biasing force is exerted on the fixing sleeve toward one side in the longitudinal direction. Then, the end of the fixing sleeve presses one fixing flange in the direction in which the shifting force acts. As a result, the fixing flange is brought into pressure contact with the support portion, and this pressure contact portion has a large sliding resistance. Even when this sliding resistance is larger than the frictional force at the contact portion between the fixing sleeve and the fixing flange, the fixing flange does not rotate with the fixing sleeve, and the end portion of the fixing sleeve rubs against the fixing flange. At this time, there was a case where the end of the fixing sleeve was cracked due to the stress at the end of the fixing sleeve (metal film) due to the friction with the fixing flange.

  An object of the present invention is to prevent cracking at the end of the fixing sleeve due to rubbing with the fixing flange, and to further extend the life of the fixing device.

  In order to achieve the above object, a typical configuration of the present invention includes a film-like rotating body, a guide member that guides the rotating body, and a recording material sandwiched and conveyed with respect to the guide member via the rotating body. In the heating apparatus, comprising: a backup member that forms a nip portion to be heated; and a heating means that heats the recording material that is controlled to maintain a set temperature while being in contact with the inner surface of the rotating body and is conveyed in the nip portion. The rotating body is formed with an elastic layer on at least a film-like metal layer, and at least one end of the axial ends of the rotating body protrudes in the axial direction from the metal layer. It is characterized by.

  According to the present invention, the axial end of the film-like rotating body has a longer elastic layer than the metal layer, and even when the axial direction (longitudinal direction) is shifted to the rotating body, The elastic layer of the rotating body first comes into contact with the axial end portion and the contact portion of the rotating body. As a result, the elastic layer receives the pressing force (shift force) of the rotating body, and the stress on the metal layer is reduced. Therefore, it is possible to prevent the occurrence of cracks due to rubbing at the axial end of the rotating body, and it is possible to further extend the life of the heating device.

  In the heating device having the above-described configuration, the axial end of the rotating body is regulated by a regulating member that is rotatably supported. According to this configuration, when a shifting force is generated and the rotating body is pressed in one axial direction, the elastic layer of the rotating body and the restricting member are pressed against each other, so that the restricting member can be rotated more reliably. It becomes possible. Thus, since the regulating member rotates reliably, the friction between the axial end portion of the rotating body and the regulating member can be reduced. Therefore, it is possible to prevent the axial end portion of the rotating body from cracking due to rubbing with the regulating member, and to further extend the life of the heating device.

  Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the drawings. However, the dimensions, materials, shapes, and relative arrangements of the components described in the following embodiments should be appropriately changed according to the configuration of the apparatus to which the present invention is applied and various conditions. As long as there is no specific description, it is not the meaning which limits the scope of the present invention only to them.

[First Embodiment]
The heating apparatus according to the first embodiment of the present invention will be described in detail with reference to FIGS. 1 to 3 by exemplifying an image forming apparatus provided as a heating and fixing apparatus for heating and fixing an image.

(Image forming device)
FIG. 3 is a cross-sectional view of the image forming apparatus including the fixing device according to the first embodiment of the present invention. In the present embodiment, a full-color image forming apparatus employing a color on-demand fixing device will be described as an example.

  The image forming apparatus shown in FIG. 3 is a fixing apparatus according to the present embodiment, which is a full color image forming apparatus that obtains a full color image by superimposing four color toner images of yellow, cyan, magenta, and black using an electrophotographic method. It incorporates a device.

  As shown in FIG. 3, in the color image forming apparatus according to this embodiment, for each color, the photosensitive drums 1Y, 1C, 1M, and 1K as image carriers and the charging rollers 2Y, 2C, 2M, and 2K as charging means are provided. In addition, the developing unit 3Y, 3C, 3M, 3K for developing the electrostatic latent image, the photosensitive drum cleaning unit 4Y, 4C, 4M, 4K, etc. are combined into one cartridge.

  Develop yellow cartridge with yellow (Y) toner in developer, magenta cartridge with magenta (M) toner in developer, cyan cartridge with cyan (C) toner in developer, and black (K) toner Four cartridges of black cartridge filled in the container are used.

  In the image forming apparatus according to the present embodiment, an optical system 5 that forms an electrostatic latent image by exposing the photosensitive drums 1Y, 1C, 1M, and 1K is provided corresponding to the four color cartridges. ing. A laser scanning exposure optical system is used as the optical system.

  Scanning light based on the image data from the optical system 5 exposes the photosensitive drums 1Y, 1C, 1M, and 1K uniformly charged by the charging units 2Y, 2C, 2M, and 2K, so that the photosensitive drums are exposed. Electrostatic latent images corresponding to images are formed on the surfaces of 1Y, 1C, 1M, and 1K. By setting the developing bias applied to the developing rollers 3Y, 3C, 3M, and 3K from a bias power source (not shown) to an appropriate value between the charged potential and the latent image (exposed portion) potential, the negative polarity is charged. The developed toner is selectively attached to the electrostatic latent images on the photosensitive drums 1Y, 1C, 1M, and 1K, thereby developing the toner.

  The monochromatic toner images developed on the photosensitive drums 1Y, 1C, 1M, and 1K are transferred onto an intermediate transfer member that rotates at a substantially constant speed in synchronization with the photosensitive drums 1Y, 1C, 1M, and 1K. . In this embodiment, an intermediate transfer belt 6 is used as an intermediate transfer member, which is driven by a driving roller 7 and stretched by a tension roller 8. Primary transfer rollers 9Y, 9C, 9M, and 9K are used as primary transfer means for transferring the toner images on the photosensitive drums 1Y, 1C, 1M, and 1K to the intermediate transfer belt 6. A toner image is primarily transferred to the intermediate transfer belt 6 by applying a primary transfer bias having a polarity opposite to that of toner from a bias power source (not shown) to the primary transfer rollers 9Y, 9C, 9M, and 9K.

  After the primary transfer, transfer residual toner remaining on the photosensitive drums 1Y, 1C, 1M, and 1K is removed by the cleaning units 4Y, 4C, 4M, and 4K. In the present embodiment, blade cleaning using a urethane blade is used as the cleaning means.

  The above process is performed for each color of yellow, magenta, cyan, and black in synchronization with the rotation of the intermediate transfer belt 6, and primary transfer toner images of the respective colors are sequentially overlapped and formed on the intermediate transfer belt 6. At the time of image formation of only a single color (monochrome mode), the above process is performed only for the target color.

  Further, the recording material P set in the recording material cassette 10 serving as a recording material supply unit is fed by a feeding roller 11 and a secondary transfer unit (the intermediate transfer belt 6 and the secondary transfer belt 6 at a predetermined timing by a registration roller 12. Nip portion with transfer means).

  The primary transfer toner image formed on the intermediate transfer belt 6 is applied on the recording material P by a bias having a polarity opposite to that of the toner applied to a secondary transfer roller 13 as a secondary transfer unit by a bias applying unit (not shown). Are collectively transferred. Reference numeral 14 denotes a secondary transfer roller facing roller.

  The secondary transfer residual toner remaining on the intermediate transfer belt 6 after the secondary transfer is removed by the intermediate transfer belt cleaning unit 15. In the present embodiment, the intermediate transfer member is cleaned with a urethane blade in the same manner as the photosensitive drum cleaning means.

  The toner image secondarily transferred onto the recording material P passes through the heat fixing device 20 that is a heating device, and is fused and fixed onto the recording material P to become an output image of the image forming apparatus.

(Fixing device F)
FIG. 2 is a cross-sectional view showing the fixing device in the present embodiment. As shown in FIG. 2, the fixing device 20 in this embodiment is a film heating type heat fixing device, and will be described below, a fixing sleeve 21 as a film-like rotating body, a heater 22 as a heating unit, A heater holder 23 as a guide member, a pressure roller 24 as a backup member, an inlet guide 25, a thermistor 26, a fixing flange 27 (see FIG. 1) as a regulating member, and the like.

  21 is a flexible metal sleeve as a film-like rotating body (cylindrical thin-walled rotating body), which is formed using a metal or alloy such as SUS (stainless steel) having heat resistance and high thermal conductivity as a base material; An elastic layer and a release layer are formed on the metal layer as the substrate. The configuration and manufacturing process of the fixing sleeve 21 will be described in detail later.

  Reference numeral 22 denotes a heater as a heating unit installed inside the fixing sleeve 21, which heats the fixing nip portion N for melting and fixing the unfixed toner image on the recording material.

  Reference numeral 23 denotes a heater holder as a guide member, which is a heat insulating heater holder for holding the heating heater 22 and preventing heat radiation to the opposite direction side of the fixing nip portion N. The heater holder 23 is made of a liquid crystal polymer resin having high heat resistance. The fixing sleeve 21 is loosely fitted around the heater holder 23 with a margin and is arranged to be rotatable in the direction of the arrow.

  Further, since the fixing sleeve 21 rotates while sliding on the internal heating heater 22 and the heater holder 23, it is necessary to keep the frictional resistance between the heating heater 22 and the heater holder 23 and the fixing sleeve 21 small. For this reason, a small amount of heat-resistant grease is applied to the surfaces of the heater 22 and the heater holder 23 as a lubricant. As a result, the fixing sleeve 21 can rotate smoothly.

  Reference numeral 24 denotes a pressure roller as a backup member. A silicone rubber layer having a thickness of about 3 [mm] is formed on the outside of a stainless steel core by injection molding, and a PFA resin having a thickness of about 40 [μm] is formed thereon. The tube is covered. The pressure roller 24 forms a fixing nip N between which the recording material is nipped and conveyed with the fixing sleeve 21.

  An entrance guide 25 serves to guide the recording material P that has passed through the secondary transfer portion so that the recording material P is accurately guided to the fixing nip portion N. The inlet guide 25 of this embodiment is formed of polyphenylene sulfide (PPS) resin.

  The pressure roller 24 and the inlet guide 25 are each assembled to a frame 29 of the fixing device 20, and a fixing sleeve 21 including a heater 22 bonded to the heater holder 23 is disposed on the pressure roller 24 and the inlet guide 25. It is pressurized with a force of 196 [N] (one side 98 [N]). The pressurization mechanism has a pressure release mechanism (not shown), and is configured such that the pressurization is released during jam processing and the recording material P can be easily removed.

  The thermistor 26 is arranged for detecting the temperature of the inner surface of the fixing sleeve 21 and performing temperature control. The thermistor 26 is attached to the tip of a stainless steel arm, and the thermistor element always contacts the inner surface of the fixing sleeve 21 even when the inner surface of the fixing sleeve 21 becomes unstable due to the arm swinging. Kept in a state. The thermistor 26 is connected to a CPU 30 as control means, and the CPU 30 determines the temperature control content of the heater 22 based on the output of the thermistor 26 and controls the energization of the heater 22.

  In FIG. 1, reference numeral 27 denotes a fixing flange as a regulating member that regulates the longitudinal position of the fixing sleeve 21. As a member used for the fixing flange 27, a material containing glass fibers such as PPS, liquid crystal polymer, PET, PI, PA, etc. as a material having excellent heat resistance, relatively poor thermal conductivity, and excellent slipperiness. Resin is used. A flange support member 28 rotatably supports the fixing flange 27 and is fixed to the frame 29 of the fixing device 20.

  In the heat fixing device 20 according to the present embodiment, the fixing sleeve 21 is driven to rotate as the pressure roller 24 rotates. Then, the recording material P on which the toner image is formed in the image forming unit is guided by the inlet guide 25 and conveyed to the fixing nip N formed by the fixing sleeve 21 and the pressure roller 24, and is heated and pressed. Thus, the unfixed toner image on the recording material P is fixed to the recording material P as a permanent image.

(Fixing sleeve)
FIG. 1 is a schematic cross-sectional view schematically showing a cross section around the end portion of the fixing sleeve. In the fixing sleeve 21, 21 b is a metal belt portion (SUS belt portion) as a metal layer formed by drawing a metal tube of SUS or the like into a seamless belt shape having a thickness of about 50 μm. 21a is a silicone rubber portion as an elastic layer adhered to the surface of the SUS belt portion 21b. For the silicone rubber portion 21a, it is desirable from the viewpoint of temperature rise to use a material having as high a thermal conductivity as possible and to reduce the heat capacity of the fixing sleeve 21. Although not shown, a PFA resin tube having a thickness of 30 μm is coated on the silicone rubber portion 21a as a release layer. Furthermore, in order to improve the releasability of the sleeve surface and prevent the offset phenomenon that occurs when the toner once adheres to the surface of the fixing sleeve 20 and moves to the recording material P again, the surface of the fixing sleeve 21 is coated with a fluororesin. A layer may be provided.

  In the fixing sleeve 21 according to the present embodiment, the silicone rubber portion 21a is fixed more than the SUS belt portion 21b so that the silicone rubber portion 21a protrudes in the axial direction (longitudinal direction) from the SUS belt portion 21b. The length is longer on the flange 27 side.

(Fixing sleeve manufacturing method)
Next, a method for manufacturing the fixing sleeve 21 will be described. The fixing sleeve 21 after the silicone rubber portion 21a is bonded to the SUS belt portion 21b is cut to a predetermined length. At the time of this cutting, a small burr | flash or level | step difference will be made in the longitudinal direction edge part of the SUS belt part 21b. In order to eliminate such burrs and steps, the longitudinal end portion of the fixing sleeve 21 after cutting is polished with a file. In this polishing with a file, burrs and steps at the end of the SUS belt portion 21b are dropped, and the end of the silicone rubber portion 21a is crushed due to the pressing force even when sliding with the file. The amount scraped off is smaller than the end of the belt portion 21b. Therefore, the silicone rubber portion 21a can be made longer than the SUS belt portion 21b by a length t toward the fixing flange 27 at the longitudinal end portion of the fixing sleeve 21. Specifically, the silicone rubber part 1 can be made approximately 30 μm longer than the SUS belt part 2 by the above-described manufacturing method.

  By using the fixing sleeve 21, the stress on the end of the SUS belt caused by the end of the SUS belt 2 rubbed against the fixing flange 3 can be reduced, and cracks are less likely to occur. Further life extension is possible.

  For example, in the cross-sectional view shown in FIG. 1, when a shift force in one axial direction (left direction in the drawing) is generated in the fixing sleeve 21, the end of the fixing sleeve 21 moves the fixing flange 27 in the same direction (left direction in the drawing). Even if a large frictional force is generated between the fixing flange 27 and the flange support member 28, the fixing flange 27 is in contact with the silicone rubber portion 21a of the fixing sleeve 21 having a large frictional resistance. It rotates with the fixing sleeve 21. As a result, the rubbing between the end of the fixing sleeve 21 and the fixing flange 27 can be minimized.

  Further, when the fixing sleeve 21 is pressed against the fixing flange 27, the silicone rubber portion 21a comes into contact with the fixing flange 27 earlier than the SUS belt portion 21b. It is relieved by the elasticity of the part 21a. As a result, the stress on the end of the SUS belt portion 21b caused by the end portion of the SUS belt portion 21b sliding on the fixing flange 27 can be reduced, and cracks are less likely to occur. Can be realized.

[Other Embodiments]
The method of manufacturing the fixing sleeve according to the present invention is not limited to the above-described embodiment. For example, a silicone rubber portion longer than the length in the longitudinal direction of the SUS belt portion is bonded to a SUS belt portion having a predetermined length. However, other manufacturing methods may be used as long as the manufacturing method is such that the silicone rubber portion is longer on the fixing flange side than the SUS belt portion, and the same effect can be obtained.

  In the above-described embodiment, an image forming apparatus capable of forming a color image is illustrated. However, the present invention is not limited to this, and may be an image forming apparatus capable of forming a monochrome image. The same effect can be obtained by applying the present invention to the fixing device in the image forming apparatus.

  In the above-described embodiments, the printer is exemplified as the image forming apparatus. However, the present invention is not limited to this, and other image forming apparatuses such as a copying machine and a facsimile machine, or a combination of these functions. Another image forming apparatus such as a multifunction peripheral or an image forming apparatus that uses a recording material carrier and sequentially superimposes and transfers the toner images of each color onto the recording material carried on the recording material carrier. The same effect can be obtained by applying the present invention to the fixing device in the image forming apparatus.

  As an application example of the image heating apparatus of the present invention, the image heating apparatus can be applied to a heat fixing apparatus mounted on various image forming apparatuses such as a printer, a copying machine, and a facsimile apparatus, and can be used alone. It can also be applied. Further, the present invention is not limited to a fixing device mounted on an electrophotographic image forming apparatus, but can also be applied to a fixing device mounted on an image forming apparatus of another recording method such as an electrostatic recording method.

FIG. 3 is a schematic cross-sectional view of the periphery of an end portion of a fixing sleeve according to the first embodiment. 1 is a cross-sectional view of a fixing device according to a first embodiment. 1 is a cross-sectional view of an image forming apparatus including a fixing device according to a first embodiment.

Explanation of symbols

N: Fixing nip portions 1Y, 1C, 1M, 1K ... Photoconductor drums 2Y, 2C, 2M, 2K ... Charging means 3Y, 3C, 3M, 3K ... Developing means 4Y, 4C, 4M, 4K ... Cleaning means 5 ... Optical system 6 ... Intermediate transfer belt 7 ... Driving roller 8 ... Tension rollers 9Y, 9C, 9M, 9K ... Primary transfer roller 10 ... Recording material cassette 11 ... Feed roller 12 ... Registration roller 13 ... Secondary transfer roller 14 ... Secondary transfer roller Opposing roller 15 ... intermediate transfer belt cleaning means 20 ... fixing device 21 ... fixing sleeve (film-like rotating body)
21a ... Silicone rubber part (elastic layer)
21b ... SUS belt part (metal layer)
22 ... Heater (heating means)
23 ... Heater holder (guide member)
24 ... Pressure roller (backup member)
25 ... Entrance guide 26 ... Thermistor 27 ... Fixing flange (regulating member)
28 ... Flange support member 29 ... Frame 30 ... CPU

Claims (3)

A film-like rotator, a guide member for guiding the rotator, a backup member for forming a nip portion for nipping and conveying the recording material to the guide member via the rotator, and an inner surface of the rotator A heating unit that heats the recording material that is controlled to contact and maintain the set temperature and that is transported in the nip portion,
The rotating body is formed with an elastic layer on at least a film-like metal layer, and at least one of the axial ends of the rotating body has the elastic layer protruding in the axial direction from the metal layer. A heating device characterized by that. The heating apparatus according to claim 1, wherein the axial end of the rotating body is regulated by a regulating member that is rotatably supported. An image forming apparatus for forming an image on a recording material, comprising the heating device according to claim 1 or 2 as a fixing device for heating and fixing an image transferred onto the recording material. Forming equipment.

Images