JP2011191708A - Fixing device and image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a fixing device in which the surface temperature of a pressing roller can be cooled without increasing the size of the device due to disposition of a blowing member such as a fan, by forming, with a material having high thermal conductivity, the cleaning web abutment member in contact with the pressing roller via a cleaning web, and by configuring an abutment member press-contacting mechanism to have a heat dissipation unit which comes into contact with the cleaning web abutment member to dissipate heat, and to provide an image forming apparatus. <P>SOLUTION: The cleaning web abutment member 12 is formed with a metal material having high thermal conductivity such as, for example, copper and aluminum, and receives heat from a pressing roller 4 and dissipates the heat via an abutment member press-contacting mechanism 13 to cool the pressing roller 4. The abutment member press-contacting mechanism 13 includes a heat sink fin 16 which comes into contact with the cleaning web abutment member 12 to dissipate heat, and thereby efficiently dissipates the heat receiving from the pressing roller 4. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a fixing device and an image forming apparatus having the fixing device, and more particularly, to a fixing device used in an image forming apparatus such as an electrophotographic copying machine, a printer, a facsimile machine, a plotter, or a multifunction machine having a plurality of functions. Relates to the device.

  In a fixing device in an image forming apparatus such as an electrophotographic printer or copying machine, the temperature of a heating roller in the fixing device is monitored, and when the temperature becomes higher than a specified value, a cooling fan is driven to be always optimal. A technique for maintaining the temperature of a simple heating roller is known (see, for example, Patent Document 1).

  In the conventional technique including the technique described in Patent Document 1, cooling by blowing air with a fan or the like is considered as a cooling means for a heating roller or a pressure roller (hereinafter abbreviated as “heating / pressure roller”). ing. However, around the heating / pressure roller, there are a temperature sensor for detecting the surface temperature of these rollers, a roll-shaped cleaning web for removing foreign matter from the surface of the heating / pressure roller, and this cleaning web as a heating / pressure roller. A cleaning mechanism having a cleaning web abutting member to be abutted is disposed, and it may be difficult to install a blowing member such as a fan.

  Accordingly, the present invention has been made in view of the above-described circumstances, and includes an endless fixing belt that conveys a sheet-like recording medium carrying a toner image, and a heating unit such as a heater around which the fixing belt is wound. A heating roller as a heating member, a fixing roller as a fixing member around which a fixing belt is wound, and a pressure roller as a pressing member arranged to face the fixing roller via the fixing belt, A scroll-like cleaning web that cleans the surface of the pressure roller, a cleaning web contact member that contacts the pressure roller via the cleaning web, and a contact member press-contact mechanism that presses the cleaning web contact member against the pressure roller A fixing device for fixing a toner image on a sheet-like recording medium, wherein the cleaning web contact member is made of a material having high thermal conductivity, The contact member press-contact mechanism has a heat dissipating means that dissipates heat by contacting the cleaning web contact member through which the heat of the pressure roller has been conducted, and by arranging a blower member such as a fan, the size of the apparatus can be increased. The main purpose is to cool the surface temperature of the pressure roller without incurring it.

In order to solve the above-described problems and achieve the above-mentioned object, the invention according to each claim employs the following characteristic means / invention-specific matters (hereinafter referred to as “configuration”).
According to the first aspect of the present invention, an endless fixing belt that conveys a sheet-like recording medium carrying a toner image, a heating member that is wound around the fixing belt and includes a heating means, and a winding member that winds the fixing belt. A fixed fixing member, a pressing member disposed to face the fixing member via the fixing belt, a scroll-like cleaning web for cleaning the surface of the pressing member, and the cleaning web. A fixing device that has a cleaning web contact member that contacts the pressure member and a contact member pressure contact mechanism that presses the cleaning web contact member against the pressure member, and fixes a toner image on the sheet-like recording medium. The cleaning web contact member is made of a material having high thermal conductivity, and the contact member press-contact mechanism is in contact with the cleaning web contact member. It characterized by having a heat dissipation means that dissipates.

  According to a second aspect of the present invention, in the fixing device according to the first aspect, the cleaning web contact member has a surface made of a material having high thermal conductivity and an inside made of an elastic material.

  According to a third aspect of the present invention, in the fixing device according to the first or second aspect, a plurality of the cleaning web contact members are provided.

  According to a fourth aspect of the present invention, in the fixing device according to any one of the first to third aspects, the cleaning web contact member abuts against the pressure member according to a surface temperature of the pressure member. A contact area variable means for changing the area is provided.

  According to a fifth aspect of the present invention, in the fixing device according to the fourth aspect, the surface temperature rising portion of the pressure member is specified from the length of the sheet-like recording medium to be conveyed and the outer peripheral length of the pressure member, The contact area is set to be large in accordance with the rotation timing of the pressure member where the surface temperature rising portion of the pressure member comes into contact with the sheet-like recording medium.

  A sixth aspect of the present invention is an image forming apparatus having the fixing device according to any one of the first to fifth aspects.

According to the present invention, it is possible to realize and provide a novel fixing device and a novel image forming apparatus having no abnormal image by solving the above problems. The effects of the invention for each claim are as follows.
According to the first aspect of the present invention, the heat transmitted from the pressure member to the cleaning web contact member can be absorbed and dissipated by the heat dissipating means. The surface temperature of the pressure member (for example, the pressure roller) can be cooled without increasing the size of the apparatus.

  According to the second aspect of the present invention, in addition to the effect of the first aspect of the invention, the contact area (contact area) between the pressure member and the cleaning web contact member while maintaining thermal conductivity can be obtained. ) Is enlarged, the cooling efficiency of the surface temperature of the pressure member can be increased.

  According to the third aspect of the present invention, in addition to the effect of the first or second aspect, the contact area between the pressure member and the cleaning web contact member is further expanded. The cooling efficiency of the surface temperature of the member can be further increased.

  According to the invention described in claim 4, in addition to the effect of the invention described in any one of claims 1 to 3, according to the above configuration, the cleaning member abuts against the heating member at a portion where the surface temperature of the heating member is high. Since the contact area of the member can be increased, the cooling effect of the surface temperature of the pressure member can be enhanced.

  According to the fifth aspect of the invention, the surface temperature increasing portion of the pressure member is specified from the length of the sheet-like recording medium to be conveyed and the outer peripheral length of the pressure member, and the surface temperature increasing portion of the pressure member is the sheet shape. By setting the contact area by the contact area variable means large in accordance with the rotation timing of the pressure member in contact with the recording medium, the pressure member can be arranged without arranging a sensor for detecting the surface temperature of the pressure member. Since the abutting area of the cleaning web abutting member with respect to the heating member can be enlarged at the surface temperature rising portion, the effect of cooling the surface temperature of the pressing member can be enhanced.

  According to the sixth aspect of the present invention, an image forming apparatus having no abnormal image can be realized and provided by having the fixing device according to any one of the first to fifth aspects.

1 is a cross-sectional view of a fixing device showing a first embodiment of the present invention. FIG. 2 is an enlarged cross-sectional view around a cleaning web unit and a contact member pressing mechanism in the fixing device of FIG. 1. 1 is a front sectional view schematically showing an overall configuration of an image forming apparatus including a fixing device according to a first embodiment. 10 is a cross-sectional view of the entire fixing device according to Modification 1. FIG. FIG. 10 is a cross-sectional view of the entire fixing device according to Modification 2. FIG. 10 is an enlarged cross-sectional view around a cleaning web unit and contact area variable means of a fixing device according to Modification 3. 10 is a timing chart illustrating a relationship between a pressure roller circumferential length according to Modification 4 and a conveyed paper length.

  Hereinafter, embodiments of the present invention including examples will be described in detail with reference to the drawings. In each embodiment and the like, components (members and components) having the same function and shape are described once unless they are confused, and the description thereof is omitted by giving the same reference numerals. In order to simplify the drawings and the description, even if the components are to be represented in the drawings, the components that do not need to be specifically described in the drawings may be omitted as appropriate. When quoting and explaining constituent elements such as published patent gazettes, the reference numerals are shown in parentheses to distinguish them from those of the embodiments.

(First embodiment)
A first embodiment of the present invention will be described with reference to FIGS. First, the operation of the image forming apparatus 100 including the fixing device 20 according to the first embodiment of the present invention will be described with reference to FIG.

An image forming apparatus 100 illustrated in FIG. 3 is a tandem type intermediate transfer type color copying machine. As shown in FIG. 1, an image forming apparatus 100 includes an apparatus main body 101, a scanner 102 that is an image reading apparatus disposed above the apparatus main body 101, and an automatic document feeding disposed further above the scanner 102. And an apparatus (ADF) 103.
A paper feed unit 104 including a plurality of paper feed cassettes 104 a, 104 b, 104 c, and 104 d is disposed at the lower part of the apparatus main body 101.

An almost endless intermediate transfer belt 105 as an intermediate transfer member is disposed at the substantially central portion of the apparatus main body 101. The intermediate transfer belt 105 is supported by being supported by a plurality of support rollers 106, 107, 108 and the like, and is rotationally driven in a clockwise direction in the drawing by a drive source (not shown).
In the vicinity of the support roller 108, an intermediate transfer body cleaning device 109 for removing residual toner and the like remaining on the intermediate transfer belt 105 after the secondary transfer is provided.
On the intermediate transfer belt 105 stretched between the support roller 106 and the support roller 107, yellow (Y), magenta (M), cyan (C), and black (K) are arranged along the conveyance direction. The process cartridges 29Y, 29M, 29C, and 29K as four image forming units are arranged and arranged in this order, and the tandem image forming unit 30 is configured. However, these four color orders are examples, and the present invention is not limited to these.

The process cartridges 29Y, 29M, 29C, and 29K are provided with drum-shaped photosensitive drums 21Y, 21M, 21C, and 21K as image carriers. Hereinafter, the configuration of the process cartridges 29Y, 29M, 29C, and 29K is the same except for the toner color in the developer corresponding to the image data color to be exposed, and the other configurations are the same. The explanation will be made generally with the reference numerals.
Around the photosensitive drum 21 in the process cartridge 29 are a protective layer forming device 22 for supplying an image carrier protecting agent to the surface of the photosensitive drum, a charging device 23 for uniformly charging the surface of the photosensitive drum, and an exposure device to be described later. A portion that receives exposure from the latent image forming device 28, a developing device 25 that supplies toner to the latent image forming portion on the surface of the photosensitive drum to visualize the toner, and a toner image on the surface of the photosensitive drum is transferred to the intermediate transfer belt 105 In addition, a transfer device 26 for primary transfer and a cleaning device 24 for cleaning residual toner on the surface of the photosensitive drum after transfer are disposed.

Above the tandem image forming unit 30, a latent image forming device 28 as an exposure device is disposed. A secondary transfer roller 110 as a transfer device is disposed on the opposite side of the intermediate transfer belt 105 from the support roller 108. By the secondary transfer roller 110, the toner image on the intermediate transfer belt 105 is transferred to a sheet as an example of a sheet-like recording medium fed from the sheet feeding unit 104.
On the left side of the secondary transfer roller 110, the fixing device 20 of the present embodiment for fixing the transferred image transferred onto the paper is disposed. The fixing device 20 has a configuration in which a pressure roller 4 as a pressure member is pressed against the fixing belt 3 having an endless belt shape. The detailed configuration and operation of the fixing device 20 will be described later.
Below the fixing device 20, a sheet reversing device 112 for reversing the paper when an image is formed on both sides of the paper is disposed substantially parallel to the tandem image forming unit 30 described above.

A series of processes for forming an image will be described by a negative-positive process, but will be briefly described by omitting a color symbol. A photosensitive drum 21 typified by a photosensitive member (OPC) having an organic photoconductive layer is neutralized by a neutralizing lamp (not shown) or the like, and is uniformly negatively charged by a charging roller of a charging device 23.
When the photosensitive drum 21 is charged by the charging device 23, an appropriate size suitable for charging the photosensitive drum 21 to a desired potential from the voltage application mechanism (not shown) to the charging device 23. Or a charging voltage obtained by superimposing an AC voltage thereon is applied.
The charged photosensitive drum 21 is subjected to latent image formation with laser light irradiated by a latent image forming device 28 such as a laser optical system. Laser light is emitted from a semiconductor laser, and the surface of the photosensitive drum 21 is scanned in the direction of the rotation axis of the photosensitive drum 21 by a polygonal polygonal mirror that rotates at high speed.

The latent image formed in this way is developed with a developer composed of toner particles or a mixture of toner particles and carrier particles supplied onto a developing sleeve (developing roller) which is a developer carrying member in the developing device 25. As a result, a visible toner image is formed. At the time of developing the latent image, a voltage of an appropriate magnitude between the exposed portion and the non-exposed portion of the photosensitive drum 21 or a development in which an AC voltage is superimposed on the developing sleeve from a voltage application mechanism (not shown). A bias is applied.
A toner image formed on the photosensitive drum 21 corresponding to each color is transferred onto the intermediate transfer belt 105 by a transfer roller 26 that constitutes a transfer device (not shown), and is fed from the paper feeding unit 104 or a manual feed tray. A toner image (color image) superimposed by the secondary transfer roller 110 is collectively transferred onto a transfer medium (sheet-like recording medium) such as paper fed from 113. Thereafter, the intermediate transfer belt 105 is separated from the photosensitive drum 21, and a transfer image is obtained.

The toner particles remaining on the photosensitive drum 21 are collected by a cleaning blade or the like in the cleaning device 24. The sheet carrying the unfixed toner image after the image transfer is conveyed to the fixing device 20 where heat and pressure are applied at the nip portion between the fixing belt 3 and the pressure roller 4 wound around the fixing roller 2. The transferred image is fixed. The fixed sheet is discharged and stacked on the discharge tray 116 by the discharge roller pair 115.
Alternatively, the conveyance path is switched by a switching claw (not shown) and conveyed to the sheet reversing device 112, where it is reversed and guided again to the transfer position, and an image is formed on the back surface. The paper is discharged and stacked on the paper tray 116. After the image transfer, the intermediate transfer belt 105 has residual toner and the like removed by an intermediate transfer belt cleaning device 109, and prepares for the image formation by the tandem image forming unit 30 again.

  With reference to FIG. 1 and FIG. 2, the fixing device 20 according to the first embodiment of the present invention will be described in detail. FIG. 1 is a cross-sectional view of the entire fixing device 20 according to the first embodiment of the present invention, and FIG. 2 is an enlarged cross-sectional view around the contact member pressing mechanism 13 of the fixing device 20.

  As shown in FIG. 1, the fixing device 20 includes an endless fixing belt 3 that conveys a sheet as a sheet-like recording medium that carries a toner image, and a heater that serves as a heating unit around the fixing belt 3. 8, the heating roller 1 as a heating member provided with 8, the fixing roller 2 as a fixing member around which the fixing belt 3 is wound, and the fixing belt 3 in the vicinity of the fixing roller 2. A temperature detection device 9 as temperature detection means for detecting the surface temperature, a pressure roller 4 as a pressure member disposed opposite to the fixing roller 2 via the fixing belt 3, and the surface of the pressure roller 4 A scroll-shaped cleaning web 11 for cleaning the cleaning web, a cleaning web abutting member 12 that abuts against the pressure roller 4 via the cleaning web 11, and a cleaning web abutting member 12 And a contact member pressing mechanism 13 indicated by the dashed line is pressed against the La 4.

  The fixing belt 3, the heating roller 1, the fixing roller 2, the pressure roller 4, the cleaning web 11, and the cleaning web contact member 12 have appropriate lengths in the axial direction of each roller, that is, from the front side to the back side in FIG. It is provided with an extension. In FIG. 1, reference numeral 19 denotes a housing that houses the above-described members of the fixing device 20. The heating roller 1, the fixing roller 2, and the pressure roller 4 are pivotally supported on the housing 19 side.

The pressure roller 4 is disposed on the fixing roller 2 via the fixing belt 3 so that it can be depressurized / pressed by a pressure contact mechanism (not shown). The heating roller 1 includes a cored bar part 5 and a surface release layer 6 such as Teflon (registered trademark), and a heater 8 is provided in the axial center hole 7 of the cored bar part 5.
In the present embodiment, for example, the fixing roller 2 is formed by forming a silicone rubber on a core metal, and the fixing belt 3 is formed by providing a silicone rubber layer on a polyimide base material and applying a PFA coat on a surface layer. The roller 4 is formed by forming a silicone rubber on the core metal and winding a PFA tube on the surface layer. Each of these is merely an example, and various combinations of materials may be used depending on the purpose and application. There is no doubt that there is.

  Heat from the heater 8 is transferred to the heating roller 1, and heat from the heating roller 1 is transferred to the fixing belt 3. For example, the surface temperature of the fixing belt 3 is detected by a temperature detection device 9 made of a thermistor or a thermopile, and the heater 8 is turned on and off so that the surface temperature is constant (eg, 135 to 180 ° C.). .

  A cleaning unit 10 is disposed opposite to the pressure roller 4. The cleaning unit 10 includes a cleaning web 11, a cleaning web contact member 12, and a contact member pressing mechanism 13. A winding shaft 14 and a feeding shaft 15 are attached to the cleaning web 11, and the cleaning web 11 is wound up by a drive mechanism (not shown). The cleaning web 11 is in the form of a roll having a thickness of about several tens of μm, and is pressed against and brought into contact with the pressure roller 4 by the cleaning web contact member 12. The cleaning web contact member 12 has a roller shape formed integrally with the shaft, and is supported by the housing 19. The winding shaft 14 and the delivery shaft 15 are rotatably supported by the housing 19.

The cleaning web contact member 12 is made of a metal material having high thermal conductivity (thermal conductivity) such as copper or aluminum, and mainly receives the heat of the pressure roller 4 and receives the heat from the contact member. The pressure roller 4 is cooled by radiating heat through the pressure contact mechanism 13. The abutting member press-contact mechanism 13 is equipped with a radiating fin 16 that contacts the cleaning web abutting member 12 and radiates heat, and is configured to efficiently radiate the heat received from the pressure roller 4. Yes. The heat radiating fins 16 are also made of a metal material having a high thermal conductivity (thermal conductivity) such as copper or aluminum.
Of the metals with the highest thermal conductivity (thermal conductivity: W / m · K), the highest order is silver, copper, gold, and aluminum. Copper and aluminum are used in consideration.

As shown in FIG. 2, the abutting member press-contacting mechanism 13 is fixed to the fin supporting member 17 having both ends fixed to portions near the cleaning web abutting member 12 at both ends of the radiating fin 16 and having a substantially U shape in plan view. The fin support member 17 is interposed between the right end in the figure and the housing 19, and the cleaning web contact member 12 is always in contact with the pressure roller 4 through the radiation fin 16, the fin support member 17 and the cleaning web 11. It is mainly comprised from the compression spring 18 as an urging | biasing means urged | biased to direction.
A plurality of compression springs 18 are arranged along the axial direction of the cleaning web contact member 12. With such an arrangement of the compression spring 18, an appropriate biasing force that forms a contact area between the pressure roller 4 and the cleaning web contact member 12 through the cleaning web 11 is applied to the cleaning web contact member 12. It is provided to be applied over the axial direction.

  In the fin support member 17, a plurality of guided pins 17 a projecting outward from the fin support member 17 (four in total, two in front of and behind the paper surface of FIG. 2) are planted integrally. . The fin support member 17 has a plurality of guided pins 17a fitted into elongated holes formed in the left-right direction in the drawing of a guide portion (not shown) provided integrally with the housing 19, so Guided in the left-right direction contacting the cleaning web contact member 12.

  Further, the contact member press-contact mechanism 13 connects a heat transfer means such as a heat pipe (not shown) to the heat radiating fins 16, transfers heat to the outside of the fixing device 20, and cools it by a blower fan or the like. It is also possible to cool the pressure roller 4 efficiently.

  As described above, according to the present embodiment, heat conducted mainly from the pressure roller 4 to the cleaning web contact member 12 can be absorbed and radiated by the radiation fins 16 (heat radiation means) of the contact member pressure contact mechanism 13. Therefore, the surface temperature of the pressure roller 4 can be cooled without increasing the size of the apparatus by disposing a blower member such as a fan as in the prior art.

(Modification 1)
With reference to FIG. 4, a fixing device 20 </ b> A according to Modification 1 of the first embodiment will be described. This figure is a cross-sectional view of the entire fixing device 20A according to the first modification. The fixing device 20A of Modification 1 is different from the fixing device 20 of the first embodiment only in that a cleaning web contact member 12A is used instead of the cleaning web contact member 12. The fixing device 20A of the first modification other than this difference is the same as the fixing device 20 of the first embodiment.

In the cleaning web contact member 12A, the contact member surface layer portion 121 including the surface is made of, for example, a highly heat conductive polyimide film, and the internal contact member interior 122 has a sponge-like elasticity. It is made of a material such as foamed silicone rubber.
The cleaning web abutting member 12A is not limited to this, and the cleaning web contact member 12A may have a multilayer structure made of an elastic material.

  As described above, according to the first modification, when the cleaning web contact member 12A comes into contact with the pressure roller 4 through the cleaning web 11 by the urging force of the contact member pressure contact mechanism 13, the thermal conductivity is maintained. Since the contact member interior 122 is elastically deformed and the contact area between the pressure roller 4 and the cleaning web contact member 12A (hereinafter also referred to as “contact area”) is expanded, the surface temperature of the pressure roller 4 is increased. The cooling efficiency can be increased.

(Modification 2)
With reference to FIG. 5, a fixing device 20B according to a second modification of the first embodiment will be described. This figure is a cross-sectional view of the entire fixing device 20B according to the second modification. The fixing device 20B of Modification 2 is different from the fixing device 20 of the first embodiment only in having a plurality of cleaning web abutting members 12 (two in the illustrated example) of the cleaning web unit 10. The fixing device 20B of Modification 2 other than this difference is the same as the fixing device 20 of the first embodiment.
Modification 1 can also be applied to Modification 1 shown in FIG. 4, and when applied, a plurality of cleaning web contact members 12A are provided.

  As described above, according to the second modification, the cleaning web unit 10 has the plurality of cleaning web contact members 12, and the contact between the pressure roller 4 and the cleaning web contact member 12 through the cleaning web 11. It is possible to further expand the area.

(Modification 3)
With reference to FIG. 6, the modification 3 of 1st Embodiment is demonstrated. FIG. 4 is an enlarged cross-sectional view of the cleaning web unit 10 of the fixing device 20C according to the third modification. The fixing device 20 </ b> C of Modification 3 has a contact area of the cleaning web contact member 12 with respect to the pressure roller 4 in accordance with the surface temperature of the pressure roller 4, as compared with the fixing device 20 of the first embodiment. The only difference is that the contact area changing means 31 is changed. The fixing device 20C of Modification 3 other than this difference is the same as the fixing device 20 of the first embodiment.

  The contact area varying means 31 is a mechanism in which the spring length of the compression spring 18 is made variable so that the pressing amount of the contact member pressure contact mechanism 13 shown in FIG. 2 can be changed. The contact area varying means 31 engages with the spring locking member 32 that locks the other end of the compression spring 18 in the contact member pressure contact mechanism 13 and is movable in the left-right direction in FIG. The eccentric cam 33 and the drive motor 34 as drive means for driving the eccentric cam 33 are mainly configured.

  The spring locking member 32 has a U-shaped cross section that is guided by the fin support member 17 so as to be movable in the left-right direction in FIG. A cam shaft 33 a of the eccentric cam 33 is rotatably supported by the housing 19. A drive motor 34 such as a stepping motor is connected to the cam shaft 33a via a drive force transmission means such as a gear (not shown).

The eccentric cam 33 shown in FIG. 6 has shown the state which the small diameter part has occupied the initial position contact | abutted to the spring latching member 32. FIG. When the large diameter portion of the eccentric cam 33 comes into contact with the spring locking member 32 by the rotational drive of the drive motor 34, the spring length of the compression spring 18 is shortened and changed, so that the pressure roller 4 of the cleaning web contact member 12 is changed. The pressing amount with respect to will change. If connected to a microcomputer equipped with a CPU, ROM, RAM, timer, etc. as a control means for controlling the rotational drive of the drive motor 34 based on the surface temperature of the pressure roller 4, the surface temperature of the pressure roller 4 Accordingly, the rotation amount of the drive motor 34 can be arbitrarily adjusted.
Needless to say, the third modification can be applied to the first modification in FIG. 4 and the second modification in FIG.

  As described above, according to the third modification, the contact area (contact area) of the cleaning web contact member 12 with respect to the heating roller 4 can be increased in the portion where the surface temperature of the heating roller 4 is high. The cooling effect of the surface temperature of 4 can be enhanced.

(Modification 4)
With reference to FIG. 7, the modification 4 of the modification 3 is demonstrated (refer Claim 5). The figure shows the relationship between the outer peripheral length of the pressure roller 4 according to the modification 4 (hereinafter referred to as “pressure roller peripheral length”) and the length of the conveyed paper S (hereinafter referred to as “paper length”). It is a timing chart showing.

  As shown in FIG. 7, when the paper S to be transported is at least the same size in the transport direction, that is, normal printing in which the same size paper S is fed for each job and printing / fixing is continuously performed. When the pressure roller 4 is in a relationship / timing between the pressure roller circumference and the sheet length so that one sheet of the sheet S is fixed by two rotations of the pressure roller 4, the pressure roller 4 The fixing belt 7 comes into contact with the sheet S between the sheet S transported before and the sheet S transported next, and the surface temperature of the part of the fixing belt 7 rises locally. Thereby, the surface temperature increasing portion of the pressure roller 4 corresponding to the local surface temperature increasing portion of the fixing belt 7 can be easily calculated from the pressure roller circumferential length L1, the paper length L2, and the inter-paper distance L3. It is. In FIG. 7, thick arrows indicate the direction of heat transfer.

For this reason, in this modification, it is possible to specify a portion where the surface temperature rises locally without specially providing the temperature detection means of the pressure roller 4. The contact area varying means of the third modification is adjusted in accordance with the rotation timing of the pressure roller 4 at which the surface temperature rising portion of the pressure roller 4 in this specific portion comes into contact with the sheet S (second sheet S in FIG. 7). 31 (see FIG. 6) is used to increase the pressing amount by the abutting member pressing mechanism 13 and to increase the contact area of the cleaning web abutting member 12 with the pressing roller 4, thereby efficiently pressing the pressing roller 4 Can be cooled.
Needless to say, the fourth modification can be applied to the first modification in FIG. 4, the second modification in FIG. 5, and the third modification.

  As described above, according to the fourth modification, since the surface temperature of the pressure roller 4 can be predicted, the heating roller can be provided without arranging a sensor for detecting the surface temperature of the pressure roller 4. 4, the contact area of the cleaning web contact member 12 with the heating roller 4 can be increased in the portion where the surface temperature of the pressure roller 4 is increased.

  As described above, the present invention has been described with respect to specific embodiments, modifications, and the like. However, the technical scope disclosed by the present invention is limited to those exemplified in the above-described embodiments, modifications, or examples. However, it should be understood that various embodiments, modifications, or examples may be configured within the scope of the present invention in accordance with the necessity and application thereof. It will be clear to the trader.

As described above, as the image forming apparatus, a plurality of developing devices are used, and a plurality of toner images with different colors sequentially produced by the plurality of developing devices are sequentially and sequentially transferred onto an intermediate transfer medium. This is not limited to the “tandem-type intermediate transfer method” in which the toner images are collectively transferred to a sheet-like recording medium such as paper and then fixed, and a plurality of similarly produced toner images having different colors are sequentially printed on the paper. "Tandem type direct transfer method" which is transferred after being superimposed on a transfer medium such as, a monochrome copying machine of an electrophotographic method, a printer or a facsimile without a scanner or ADF, etc. Of course there may be.
In addition, on a sheet-like recording medium or sheet-like medium, an image can be formed, printed or recorded on paper, transfer paper, or an OHP film sheet, and an unfixed toner image carried thereon can be fixed and conveyed. Everything is included.

1 Heating roller (heating member)
2 Fixing roller (fixing member)
3 Fixing belt 4 Pressure roller (Pressure member)
8 Heater (heating means)
9 Temperature detection device (temperature detection means)
DESCRIPTION OF SYMBOLS 10 Cleaning unit 11 Cleaning web 12 Cleaning web contact member 13 Contact member press-contact mechanism 14 Winding shaft 15 Delivery shaft 16 Radiation fin (heat radiation means)
17 Fin support member 18 Compression spring (biasing means)
19 Housing 20, 20A, 20B, 20C Fixing device 21 Photosensitive drum (image carrier)
Reference Signs List 30 tandem image forming unit 31 abutting area varying means

JP 2009-75374 A

Claims (6)

An endless fixing belt for conveying a sheet-like recording medium carrying a toner image, a heating member around which the fixing belt is wound and provided with a heating means, a fixing member around which the fixing belt is wound, A pressure member disposed to face the fixing member via a fixing belt, a scroll-like cleaning web for cleaning the surface of the pressure member, and a cleaning contacting the pressure member via the cleaning web A fixing device that fixes a toner image on the sheet-like recording medium, comprising: a web contact member; and a contact member pressure contact mechanism that presses the cleaning web contact member against the pressure member.
The fixing is characterized in that the cleaning web contact member is made of a material having high thermal conductivity, and the contact member pressure contact mechanism has a heat radiating means for radiating heat in contact with the cleaning web contact member. apparatus.   The fixing device according to claim 1, wherein the cleaning web contact member has a surface made of a material having high thermal conductivity and an inside made of an elastic material.   The fixing device according to claim 1, wherein a plurality of the cleaning web contact members are provided.   4. A contact area varying means for changing a contact area of the cleaning web contact member with the pressure member according to a surface temperature of the pressure member. The fixing device according to 1. From the length of the sheet-like recording medium to be conveyed and the outer peripheral length of the pressure member, the surface temperature rising portion of the pressure member is specified,
The fixing device according to claim 4, wherein the contact area is set to be large in accordance with a rotation timing of the pressure member where the surface temperature rising portion of the pressure member contacts the sheet-like recording medium.   An image forming apparatus comprising the fixing device according to claim 1.

Images