JP6701569B2 - Fixing device and image forming apparatus - Google Patents

Description

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

  Conventionally, a heating element is provided on the inner peripheral surface side of an endless fixing member, and a pressure roller, which is a pressure rotating member, is pressed against a nip forming member with the fixing member sandwiched between the nip portion to form a nip portion. There is known a fixing device that allows a recording material to pass through the nip portion and fixes an image on the recording material.

  For example, in the fixing device according to Patent Document 1, the outer peripheral surface of the fixing belt, which is a fixing member, is brought into contact with the outer peripheral surface of the pressure roller in a pressurized state by the fixing member, which is a nip forming member supported by the reinforcing member. However, a fixing device in which the fixing belt rotates with the rotation of the pressure roller is disclosed. In the fixing device, a sheet-like member that is a lubricant holding member that holds a fluorine-based lubricant is interposed between the fixing member and the inner peripheral surface of the fixing belt. Further, a halogen heater as a heating element is provided on the inner peripheral surface side of the fixing belt, and the halogen heater heats the inner peripheral surface of the fixing belt on the upstream side in the fixing belt moving direction with respect to the nip portion. Then, the heated portion of the fixing belt reaches the nip portion as the fixing belt rotates along with the rotation of the fixing belt, so that the sheet-shaped member is heated and the viscosity of the lubricant held by the sheet-shaped member is lowered. It is said that the sliding performance of the fixing belt with respect to the sheet-shaped member can be improved in the nip portion.

Normally, in the fixing device, the temperature of the entire fixing belt is lower than the fixable temperature when the power is turned on or when printing is requested.
According to the fixing device disclosed in Patent Document 1, the fixing member exists between the halogen heater and the sheet-shaped member, and prevents the heat of the halogen heater from being transferred to the sheet-shaped member. Therefore, after the power is turned on or a print request is made, the sheet-shaped member in the nip portion is not heated until the heated portion of the fixing belt heated by the halogen heater reaches the nip portion. The viscosity remains high. As a result, the static frictional force between the sheet-shaped member and the inner peripheral surface of the fixing belt is the static frictional force between the outer peripheral surface of the pressure roller and the fixing belt or the surface of the recording material and the fixing belt with the recording material interposed. If it exceeds the static frictional force with the outer peripheral surface of the fixing belt, the fixing belt may not rotate.

In order to solve the above-mentioned problems, the present invention provides a rotatable endless fixing member, a pressure rotating body that contacts and pressurizes the outer peripheral surface of the fixing member, and an inner peripheral surface side of the fixing member. A nip forming member that is arranged and forms a nip portion with the pressure rotating body through the fixing member, a heating element that heats the inner peripheral surface of the fixing member, and a lubricant holding member that holds a lubricant. In the fixing device, the lubricant holding member is interposed between the nip forming member and the inner peripheral surface of the fixing member, and a recording material is passed through the nip portion to fix an image on the recording material. , A support for supporting the nip forming member is provided, and the support has the heating element as heat transfer means for transmitting the heat of the heating element to the lubricant holding member while the fixing member is stopped. It is characterized in that an opening portion is provided to connect the space to be opened and the space in which the sheet-shaped lubricant holding member wound around the nip forming member exists .

  According to the present invention, it is possible to obtain the unique effect that the fixing member can be rotated after the power is turned on or the printing is requested.

FIG. 3 is a sectional view of the fixing device 20 according to the embodiment. 1 is a schematic configuration diagram of an image forming apparatus 1 according to an embodiment. Sectional drawing which shows an example of the conventional fixing device. FIG. 11 is a cross-sectional view showing an example of a conventional fixing device 220. Sectional drawing which shows an example of the fixing device 20 of this embodiment. Sectional drawing which shows another example of the fixing device 20 of this embodiment. FIG. 6 is a cross-sectional view showing the configuration of a nip forming member 124. FIG. 8 is an exploded sectional view of the nip forming member 124 of FIG. 7. FIG. 6 is a cross-sectional view showing another configuration of the nip forming member 124. FIG. 10 is an exploded sectional view of the nip forming member 124 of FIG. 9. (A) is a perspective view of three views showing a specific shape of the nip forming member 124, (b) is a side view seen from the axial direction, and (c) is a plan view seen from the nip side. The side view seen from the axial direction which shows another example of the nip forming member 124. Sectional drawing which shows another example of the opening part 130. FIG. 3 is a plan view showing an arrangement example of openings 130. FIG. 3 is a perspective view of a nip forming member and its peripheral members. The side view when the sliding sheet 131 is wound around the nip forming member 124. FIG. 6 is a perspective view of a sliding sheet 131 having an opening 131a wound around a nip forming member 124.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. In each of the drawings for describing the embodiments of the present invention, components such as members and components having the same function or shape are given the same reference numerals as far as possible to distinguish them from each other. Then, the explanation is omitted.

FIG. 2 is a schematic configuration diagram of the image forming apparatus 1 according to the present embodiment.
The image forming apparatus 1 shown in FIG. 2 is a tandem type color laser printer, and an image forming unit (four image forming units in the example shown in FIG. 2) that forms a plurality of color images in the central portion of the apparatus body. An imaging station consisting of

  The plurality of image forming units are juxtaposed along the extension direction of the intermediate transfer belt 11 as an endless belt-shaped intermediate transfer member. Then, the configuration is the same except that developers of different colors of yellow (Y), magenta (M), cyan (C), and black (Bk) corresponding to the color separation components of the color image are stored. ..

  In FIG. 2, in the image forming apparatus 1, photosensitive drums 120Y, 120C, 120M, and 120Bk as a plurality of image carriers corresponding to the colors separated into yellow, cyan, magenta, and black are arranged in parallel. ing.

  The toner image, which is a visible image of each color formed on each photoconductor drum 120Y, 120C, 120M, 120Bk, is an intermediate transfer that is movable in the direction of arrow A1 while facing each photoconductor drum 120Y, 120C, 120M, 120Bk. The primary transfer process is performed on the belt 11. As a result, the toner images of the respective colors are superimposed and transferred onto the intermediate transfer belt 11. After that, the toner images of the respective colors superposed and transferred onto the intermediate transfer belt 11 are collectively transferred onto the paper P by performing a secondary transfer process on the paper P as a recording material.

  Around the photoconductor drums 120Y, 120C, 120M, and 120Bk, various devices for performing image forming processing according to the rotation of the photoconductor drums 120 are arranged.

  Here, the photosensitive drum 120Bk that forms a black image will be described. Around the photosensitive drum 120Bk, a charging device 30Bk, a developing device 40Bk, a primary transfer roller 12Bk as a primary transfer unit, and a cleaning device 50Bk, which perform image forming processing along the rotation direction of the photosensitive drum 120Bk, are provided. It is arranged. To write an electrostatic latent image on the charged photoconductor drum 120Bk, an optical writing device 8 is used as an exposure unit that exposes the surface of the photoconductor drum 120Bk.

  The optical writing device 8 includes a semiconductor laser as a light source, a coupling lens, an fθ lens, a toroidal lens, a folding mirror, a rotating polygon mirror (polygon mirror) as an optical deflecting unit, and the like. The optical writing device 8 irradiates the surface of each of the photoconductor drums 120Y, 120C, 120M, and 120Bk with writing light (laser light) Lb based on the image data, and the photoconductor drums 120Y, 120C, 120M, and 120Bk are statically illuminated. It is configured to form a latent image.

  In the superimposed transfer onto the intermediate transfer belt 11, the visible image (toner image) formed on the photoconductor drums 120Y, 120C, 120M, and 120Bk is an intermediate transfer belt when the intermediate transfer belt 11 moves in the A1 direction in FIG. It is performed so as to be superimposed and transferred to 11 same positions.

  More specifically, the primary transfer bias is applied to each of the plurality of primary transfer rollers 12Y, 12C, 12M, and 12Bk that are arranged to face the photoconductor drums 120Y, 120C, 120M, and 120Bk with the intermediate transfer belt 11 interposed therebetween. Is applied. The toner images formed on the photoconductor drums 120Y, 120C, 120M, and 120Bk by the primary transfer rollers 12Y, 12C, 12M, and 12Bk to which the primary transfer bias is applied are superimposed with the timing shifted in the rotation direction of the intermediate transfer belt. Transcribed.

  The plurality of primary transfer rollers 12Y, 12C, 12M, and 12Bk sandwich the intermediate transfer belt 11 between the corresponding photosensitive drums 120Y, 120C, 120M, and 120Bk to form a primary transfer nip.

  A power source is connected to each of the primary transfer rollers 12Y, 12C, 12M and 12Bk. Then, a primary transfer bias composed of at least one of a predetermined DC voltage (DC voltage) and an AC voltage (AC voltage) is applied to each of the primary transfer rollers 12Y, 12C, 12M, 12Bk by this power source. There is.

  The photoconductor drums 120Y, 120C, 120M, 120Bk are arranged in this order from the upstream side in the A1 direction in FIG. The photoconductor drums 120Y, 120C, 120M, and 120Bk are provided in a plurality of image forming units that respectively form yellow, cyan, magenta, and black images.

  Further, the image forming apparatus 1 includes a transfer belt unit 10, a secondary transfer roller 5, a transfer belt cleaning device 13, and an optical writing device 8 in addition to a plurality of image forming units.

  The transfer belt unit 10 includes a plurality of belt supporting members such as an intermediate transfer belt 11 and a plurality of primary transfer rollers 12Y, 12C, 12M, and 12Bk, and a driving roller 72 and a driven roller 73 around which the intermediate transfer belt 11 is wound. Is equipped with. When the driving roller 72 is rotationally driven, the intermediate transfer belt 11 is rotated in the direction indicated by arrow A1 in FIG.

  The drive roller 72 also functions as a secondary transfer backup roller that faces the secondary transfer roller 5 via the intermediate transfer belt 11. The driven roller 73 also functions as a cleaning backup roller that faces the transfer belt cleaning device 13 via the intermediate transfer belt 11. Further, since the driven roller 73 also has a function as a tension urging means for the intermediate transfer belt 11, the driven roller 73 is provided with an urging means using a spring or the like. The transfer device 71 is configured to include the transfer belt unit 10, the primary transfer rollers 12Y, 12C, 12M, and 12Bk, the secondary transfer roller 5, and the transfer belt cleaning device 13.

  The secondary transfer roller 5 is disposed so as to face the intermediate transfer belt 11, and is driven by the intermediate transfer belt 11 to rotate together. Further, the secondary transfer roller 5 forms a secondary transfer nip by sandwiching the intermediate transfer belt 11 with the drive roller 72 that also functions as a secondary transfer backup roller.

  Further, similarly to the primary transfer rollers 12Y, 12C, 12M, and 12Bk, a power source is connected to the secondary transfer roller 5 and at least one of a predetermined DC voltage (DC voltage) and AC voltage (AC voltage) is applied. Then, the secondary transfer bias is applied to the secondary transfer roller 5.

  The transfer belt cleaning device 13 is arranged so as to face the driven roller 73 via the intermediate transfer belt 11 and cleans the surface of the intermediate transfer belt 11. In the example shown in FIG. 2, the transfer belt cleaning device 13 has a cleaning brush and a cleaning blade that are arranged so as to contact the intermediate transfer belt 11. The waste toner transfer hose extending from the transfer belt cleaning device 13 is connected to the inlet of the waste toner container.

  Further, the image forming apparatus 1 includes a sheet feeding device 61 in which sheets P as recording materials are stacked and stored, a registration roller pair 4 as recording material feeding means, and a sheet leading edge sensor as recording material leading edge detecting means. Is provided.

  The sheet feeding device 61 is provided in the lower portion of the main body of the image forming apparatus 1 and has a feeding roller 3 as a recording material feeding unit that contacts the upper surface of the uppermost sheet P. Then, the feeding roller 3 is rotationally driven in the counterclockwise direction in FIG. 2 so that the uppermost sheet P is fed toward the registration roller pair 4.

  Further, inside the main body of the image forming apparatus, there is provided a paper conveyance path for ejecting the paper P from the paper feeding device 61 through the secondary transfer nip to the outside of the device. A registration roller pair 4 that conveys the paper P to the secondary transfer nip is provided upstream of the position of the secondary transfer roller 5 in the paper conveyance path in the paper conveyance direction.

  The registration roller pair 4 forms a sheet P conveyed from the sheet feeding device 61 with the secondary transfer roller 5 at a predetermined timing matched with the toner image formation timing by the image station including the plurality of image forming units. The sheet is fed toward the secondary transfer nip between the intermediate transfer belt 11. The paper leading edge sensor detects that the leading edge of the paper P has reached the registration roller pair 4.

  Here, the paper P as a recording material includes thick paper, postcards, envelopes, thin paper, coated paper (coated paper, art paper, etc.), tracing paper, OHP sheets, recording sheets, etc. in addition to plain paper. .. In addition to the paper feeding device 61, a manual paper feeding mechanism may be provided so that the paper P can be manually fed.

  Further, the image forming apparatus 1 includes a fixing device 20 as a fixing unit for fixing the toner image on the sheet P on which the toner image is transferred, a discharge roller 7 as a recording material discharging unit, and a recording material stacking unit. And a paper discharge tray 17 of. The paper discharge roller 7 discharges the fixed paper P to the outside of the main body of the image forming apparatus 1. The paper discharge tray 17 is arranged at the upper part of the main body of the image forming apparatus 1, and stacks and stores the paper P discharged by the paper discharge rollers 7 to the outside of the main body of the image forming apparatus 1.

  The image forming apparatus 1 also includes toner bottles 9Y, 9C, 9M, and 9Bk as a plurality of toner containers. A plurality of toner bottles 9Y, 9C, 9M, and 9Bk are filled with toners of yellow, cyan, magenta, and black, respectively, and are provided above the image forming apparatus main body and below the paper discharge tray 17. It is detachably attached to each of the bottle accommodating parts.

  Further, a replenishing path is provided between each toner bottle 9Y, 9C, 9M, 9Bk and each developing device 40Y, 40C, 40M, 40Bk. Then, the toner is supplied from the toner bottles 9Y, 9C, 9M, 9Bk to the corresponding developing devices 40Y, 40C, 40M, 40Bk via this supply path.

  Although not shown in detail, the transfer belt cleaning device 13 provided in the transfer device 71 has a cleaning brush and a cleaning blade which are arranged so as to contact the intermediate transfer belt 11.

  By the cleaning brush and the cleaning blade, foreign matter such as residual toner on the intermediate transfer belt 11 is scraped off and removed, and the intermediate transfer belt 11 is cleaned. The transfer belt cleaning device 13 has a discharging unit for carrying out and discarding the residual toner removed from the intermediate transfer belt 11.

Next, the basic operation of the image forming apparatus 1 will be described.
When the image forming operation is started in the image forming apparatus 1, the photoconductor drums 120Y, 120C, 120M, 120Bk in each image forming unit are rotationally driven in the clockwise direction in FIG. 2 by the driving device. Then, the surfaces of the photoconductor drums 120Y, 120C, 120M, 120Bk are uniformly charged to a predetermined polarity by the charging devices 30Y, 30C, 30M, 30Bk.

  The surface of each of the charged photoconductor drums 120Y, 120C, 120M, 120Bk is irradiated with a laser beam from the optical writing device 8, and the surface of each of the photoconductor drums 120Y, 120C, 120M, 120Bk is electrostatically latent. An image is formed. At this time, the image information exposed on each of the photoconductor drums 120Y, 120C, 120M, and 120Bk is monochromatic image information in which a desired full-color image is decomposed into color information of yellow, magenta, cyan, and black.

  In this way, toner is supplied to the electrostatic latent images formed on the photoconductor drums 120Y, 120C, 120M, and 120Bk by the developing devices 40Y, 40C, 40M, and 40Bk. The image is visualized (visualized).

  Further, when the image forming operation is started, the drive roller 72 is rotationally driven counterclockwise in FIG. 2 to rotate the intermediate transfer belt 11 in the direction of arrow A1 in FIG. Then, to each of the primary transfer rollers 12Y, 12C, 12M, and 12Bk, a constant voltage having a polarity opposite to the charging polarity of the toner or a constant-current-controlled voltage is applied. As a result, a predetermined transfer electric field is formed in the primary transfer nip between each primary transfer roller 12Y, 12C, 12M, 12Bk and each photoconductor drum 120Y, 120C, 120M, 120Bk.

  After that, the toner images on the photoconductor drums 120Y, 120C, 120M, and 120Bk are sequentially superimposed and transferred onto the intermediate transfer belt 11 by the transfer electric field formed in the primary transfer nip, and a full-color image is formed on the surface of the intermediate transfer belt 11. Toner image is carried.

  Further, the toner on each of the photoconductor drums 120Y, 120C, 120M and 120Bk that could not be transferred to the intermediate transfer belt 11 is removed by the cleaning devices 50Y, 50C, 50M and 50Bk. After that, the surface of each of the photoconductor drums 120Y, 120C, 120M, and 120Bk is discharged by the discharging device, and the surface potential is initialized.

  In the lower part of the image forming apparatus 1, the feeding roller 3 starts to rotate and the sheet P is fed from the sheet feeding device 61 to the conveyance path. The sheet P sent out to the transport path is sent to the secondary transfer nip between the drive roller 72 and the secondary transfer roller 5, which also function as a secondary transfer backup roller, at a timing by the registration roller pair 4. Be done. At this time, a transfer voltage having a polarity opposite to the toner charging polarity of the toner image on the intermediate transfer belt 11 is applied to the secondary transfer roller 5, and a predetermined transfer electric field is formed in the secondary transfer nip. ..

  After that, when the toner image on the intermediate transfer belt 11 reaches the secondary transfer nip as the intermediate transfer belt 11 rotates, the toner on the intermediate transfer belt 11 is generated by the transfer electric field formed in the secondary transfer nip. The image is collectively transferred onto the paper P.

  At this time, the residual toner on the intermediate transfer belt 11 that could not be transferred to the paper P at this time is removed by the transfer belt cleaning device 13, and the removed toner is conveyed to the waste toner container and collected.

  After that, the paper P is conveyed to the fixing device 20, and the toner image on the paper P is fixed on the paper P by the fixing device 20. Then, the paper P is discharged to the outside of the apparatus by the paper discharge roller 7 and is stocked on the paper discharge tray 17.

  Here, as is well known, an electrophotographic image forming apparatus outputs a copied image through the following steps. That is, the electrostatic latent image formed on the photoconductor, which is a latent image carrier, is subjected to visible image processing with toner, and the toner image is transferred onto a recording medium such as paper and then fixed, whereby a copied image is formed. Is output.

  The fixing method used in the image forming apparatus includes a heat roller fixing method, a belt fixing method, a film fixing method and an electromagnetic induction heating fixing method.

  In the heat fixing roller system, a fixing roller and a pressure roller that is a pressure rotating body and are in contact with each other while sandwiching a sheet conveyance path while facing each other. In this method, the toner image is melted and permeated into the sheet by the action of heat from a heat source provided in the fixing roller and the action of pressure applied from the pressure roller. The phenomenon in which the toner image melts and permeates the paper is the same in the fixing system having the following configuration.

  In the belt fixing method, instead of the fixing roller, a fixing belt which is a good conductor of heat, a pressure roller, a roller around which the belt is wound, and a heating source for the belt are used.

  In the film fixing method, instead of the fixing roller, a fixing belt which is a good conductor of heat, a pressure roller, a roller around which the belt is wound, and a heating source for the belt are used.

  The electromagnetic induction heating fixing system uses a configuration in which an electromagnetic induction coil that enhances heat generation efficiency is provided on a heating member.

The fixing method has the following required problems.
Shortening the warm-up time, and further shortening the first print time. The warm-up time is the time required from a normal temperature state to a predetermined printable temperature (reload temperature) such as when the power is turned on. Further, the first print time is a time required until a print operation is performed after a print request is received, a print operation is performed, and paper discharge is completed.

In the fixing device, defective fixing may occur due to the following reasons.
The image forming apparatus is an apparatus capable of high-speed processing. When the number of fixed sheets per unit time by high-speed processing, that is, the number of sheets passing through the fixing device increases, the amount of heat supplied to the sheet P moving at high speed must also be increased. This is because the amount of heat required for fixing is applied to the paper as the paper P passes through the fixing device in a shorter time.

  However, if the required amount of heat is not secured at the beginning of continuous printing, the temperature will drop significantly, and if paper is passed without reaching the required amount of heat during high-speed continuous printing, fixing failure may occur. ..

  In addition, as the speed of image forming apparatuses 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 may be insufficient at the beginning of continuous printing, so-called temperature drop may be a problem. However, there is a problem that fixing failure occurs when the speed is increased.

  On the other hand, in addition to the fixing method described above, there is a fixing method called a surf fixing method using a ceramic heater.

  The surf fixing method uses a configuration in which only the nip portion is locally heated and the other portions are not heated. In this fixing method, the heat capacity and the size can be reduced as compared with the belt type fixing device, so that it is possible to rise to a predetermined temperature and shorten the first printing time, but there are the following problems.

  In other words, in the surf-fixing method, the fixing belt is in the coldest state at the entrance of the paper or the like in the nip, since the parts other than the local area are not heated, and there is a problem that defective fixing is likely to occur. In particular, in a high-speed machine, the fixing belt rotates quickly, and the heat radiation of the belt other than the nip portion increases, so that there is a problem that fixing failure is more likely to occur.

  Therefore, in order to deal with such a problem, there has been proposed a fixing device having a configuration using a fixing belt and capable of obtaining a good fixing property even when mounted in a high-production image forming apparatus.

The fixing device uses the configuration shown in FIG.
The fixing belt 100, the pipe-shaped metal heat conductor 200 arranged inside the fixing belt 100, the heat source 300 arranged in the metal heat conductor 200, and the metal heat conductor 200 via the fixing belt 100. And a pressure roller 400 that abuts against the nip portion N to form a nip portion N.

  The fixing belt 100 is rotated by the rotation of the pressure roller 400 and moves in the circumferential direction, and at this time, the metal heat conductor 200 guides the movement of the fixing belt 100. Further, the heat source 300 in the metal heat conductor 200 heats the fixing belt 100 via the metal heat conductor 200, so that the entire fixing belt 100 can be heated. As a result, it is possible to reduce the first print time from the heating standby time, and it is possible to eliminate the shortage of heat during high-speed rotation.

  However, in order to further save energy and improve the first print time, it is necessary to further improve the thermal efficiency.

  Next, the configuration of the fixing device 20 according to the present exemplary embodiment will be described with reference to FIG. FIG. 1 is a cross-sectional view of the fixing device 20 according to this embodiment.

  The fixing device 20 includes a fixing belt 21 as a fixing member, which is a surface-endless movable body having a hollow inside, and a pressure roller 22 formed of an opposed rotating body rotatably provided so as to face the fixing belt 21. There is.

  Provided inside the fixing belt 21 are a halogen heater 23 that is a heating element that heats the fixing belt 21, and a nip forming member 124 that forms a nip portion N with the pressure roller 22 that faces the fixing belt 21. There is. Further, a reflection member 25 that reflects the radiant heat from the halogen heater 23 to the inner peripheral surface of the fixing belt 21, a separating plate 26 that separates the paper P from the fixing belt 21, and a pressing roller 22 that presses the fixing roller 21 to the fixing belt 21. Also equipped with pressure means.

  Further, flanges as belt holding members are inserted at both ends of the fixing belt 21 in the width direction, and the fixing belt 21 is rotatably held by the flanges.

  As the fixing belt 21, a thin and flexible endless belt member (including a film) is used. The fixing belt 21 has a base material on the inner peripheral side formed of a metal material such as nickel or stainless steel (SUS) or a resin material such as polyimide (PI). In addition, a release layer on the outer peripheral side formed of tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer (PFA) or polytetrafluoroethylene (PTFE) is provided, and releasability is provided so that toner does not adhere. There is. An elastic layer made of a rubber material such as silicone rubber may be interposed between the base material and the release layer.

  When the elastic layer is not provided, the heat capacity is reduced and the fixability is improved. However, when the unfixed toner is crushed and fixed, there is a possibility that minute irregularities on the surface of the belt are transferred to the image, leaving a scratched skin-like mark on the solid portion of the image. To improve this, it is desirable to provide an elastic layer having a thickness of 100 μm or more. By providing the elastic layer having a thickness of 100 [μm] or more, minute irregularities can be absorbed by elastic deformation of the elastic layer, and thus it is possible to suppress the appearance of a wrinkled skin-like mark on the solid portion of the image. it can.

  The pressure roller 22 includes a cored bar 22a, an elastic layer 22b, and a release layer 22c. The elastic layer 22b is disposed on the surface of the cored bar 22a, and foamable silicone rubber, silicone rubber, fluororubber or the like is used. The release layer 22c is provided on the surface of the elastic layer 22b, and PFA, PTFE, or the like is used.

  The pressure roller 22 is pressed against the fixing belt 21 side by a spring or the like as a pressure unit, and is in contact with the nip forming member 124 via the fixing belt 21. At a position where the pressure roller 22 and the fixing belt 21 are in pressure contact with each other, the elastic layer 22b of the pressure roller 22 is crushed to form a nip portion N having a predetermined width.

  The pressure roller 22 is rotationally driven by a drive source such as a motor provided in the main body of the image forming apparatus. When the pressure roller 22 is rotationally driven, the driving force is transmitted to the fixing belt 21 at the nip portion N, so that the fixing belt 21 is driven to rotate (rotate together).

  In the present embodiment, the pressure roller 22 is a solid roller, but it may be a hollow roller. In that case, a heat source such as a halogen heater may be provided inside the pressure roller 22.

  The elastic layer 22b may be solid rubber, but sponge rubber may be used when there is no heat source inside the pressure roller 22. Sponge rubber is more preferable because the heat insulating property is improved and the heat of the fixing belt 21 is less likely to be taken away. Further, the fixing belt 21 and the pressure roller 22 are not limited to the case where they are brought into pressure contact with each other, and it is also possible to adopt a configuration in which they are simply brought into contact with each other without applying pressure.

  In the fixing device 20 shown in FIG. 1, the fixing belt 21 is directly heated by the radiant heat (heater light) from the halogen heater 23, and the halogen heater 23 as a heat source is provided inside the fixing belt 21.

  The halogen heater 23 is configured to generate heat by being supplied with electric power by a power supply which is a power supply means provided in the main body of the image forming apparatus 1 and whose output is controlled.

  The output control of the halogen heater 23 by the power source is performed so as to control the on/off or energization amount of the halogen heater 23 based on the detection result of the surface temperature of the fixing belt 21 by the temperature sensor, for example. By controlling the output of the halogen heater 23, the temperature of the fixing belt 21 can be set to a desired temperature (fixing temperature).

  As the heat source for heating the fixing belt 21, an IH (electromagnetic induction heating) heater, a resistance heating element, a ceramic heater, a carbon heater, or the like may be used instead of the halogen heater.

  A temperature sensor that detects the temperature of the pressure roller 22 is provided instead of the temperature sensor that detects the temperature of the fixing belt 21, and the temperature of the fixing belt 21 is predicted based on the temperature detected by the temperature sensor. Good.

  The surface of the nip forming member 124 facing the fixing belt 21 is provided with slidable coating. The nip forming member 124 is arranged in a longitudinal shape in the axial direction of the fixing belt 21 or the axial direction of the pressure roller 22.

  The shape of the nip portion N is determined by the nip forming member 124 receiving the pressure of the pressure roller 22. In the present embodiment, the nip portion N has a flat shape, but it may have a concave shape or another shape. When the shape of the nip portion N is concave, the discharge direction of the front end of the paper P is closer to the pressure roller 22 and the separability is improved, so that the occurrence of jam is suppressed.

  The slidable coating is provided to reduce sliding friction when the fixing belt 21 rotates.

  The nip forming member 124 is composed of a heat resistant member having a heat resistant temperature of 300[° C.] or higher, such as a metal member or a ceramic member, and the heat resistance is significantly improved as compared with the case of using a resin member. This prevents deformation of the nip forming member 124 due to heat in the toner fixing temperature range, secures a stable state of the nip portion N, and stabilizes the output image quality.

  Further, by forming the nip forming member 124 with a metal material having high mechanical strength such as stainless steel or iron, it is possible to reduce the bending due to the pressing force from the pressure roller 22 or the like.

  A stay 125 as a support supports the nip forming member 124 and is made of stainless steel or the like. The stay 125 is provided with an opening 130 penetrating in the direction from the halogen heater 23 to the nip forming member 124. As a result, the portion of the sliding sheet 131 wound around the nip forming member 124 facing the opening 130 is exposed to the halogen heater 23, and the exposed portion of the sliding sheet 131 is directly heated by the halogen heater 23. It A plurality of the openings 130 are provided side by side in the longitudinal direction of the stay 125, for example. The number and arrangement of the openings 130 are determined so as not to affect the strength of the stay 125 and the like.

  Further, as shown in FIG. 1, a sliding sheet 131, which is a fluorine-based lubricant holding member having good slidability, is wound around the nip forming member 124. Then, the sliding sheet 131 is screwed to the surface of the nip forming member 124 on the opposite side to the nip portion by a fixing member 133 described later to reduce the sliding load between the nip forming member 124 and the inner peripheral surface of the fixing belt. This suppresses the occurrence of a slip phenomenon in which the paper is not fed at the linear speed in the nip portion N because the frictional resistance increases and the torque increases due to the abrasion between the nip forming member 124 and the inner peripheral surface of the fixing belt 21. ing.

  FIG. 4 is a diagram showing an example of a conventional fixing device 220. The basic structure of the conventional fixing device 220 other than the structure related to the stay 125 is substantially the same as that of the fixing device 20 of the present embodiment described with reference to FIG. 1, and thus the description thereof is omitted.

  In the conventional fixing device 220 shown in FIG. 4, the entire temperature of the fixing belt 21 is lower than a predetermined fixable temperature when the power is turned on or when printing is requested. After that, the halogen heater 23 generates heat to heat the portion of the fixing belt 21 (the portion surrounded by the dotted line in FIG. 4) on the upstream side of the entrance of the nip portion N in the fixing belt moving direction, and the heated portion thereof is fixed belt 21. By reaching the nip portion N with the rotation of, the fixing is possible. However, the sliding sheet 131 in the nip portion N is not heated while the portion of the fixing belt 21 heated by the halogen heater 23 reaches the nip portion N after the power is turned on or the printing is requested. Therefore, the viscosity of the lubricant held by the sliding sheet 131 remains high. As a result, the fixing belt 21 may not be able to rotate together.

  Further, since the fixing belt 21 does not have a drive source such as a motor, if the frictional load on the inner peripheral surface of the fixing belt 21 is large, the fixing belt 21 may not rotate and the paper may jam. In particular, the degree of deterioration of the lubricant, which causes a frictional load on the inner peripheral surface of the fixing belt 21, has a great influence. Further, the viscosity of the lubricant deteriorates with time due to evaporation of the base oil component, oxidation and mixing of foreign matters. In particular, the degree of deterioration increases in a high temperature environment. For example, in the case of fluorine grease, in a high temperature environment of 200[°C] or higher, the evaporation of the base oil component is more than twice that in a high temperature environment of 200[°C] or lower. become. For example, when the viscosity of the lubricant increases with time, the fixing belt 21 does not rotate or rotates in a slip state even if a conventional driving force is applied from the pressure roller, and the temperature of the heated portion of the fixing belt 21 rapidly increases. Due to the heat deformation, a scar is left on the output image. This is because the fixing belt 21 does not rotate, the heat of the halogen heater 23 is not transmitted to the nip portion N, and the viscosity of the lubricant remains high.

FIG. 5 is a cross-sectional view showing an example of the fixing device 20 of this embodiment.
Therefore, in the present embodiment, as shown in FIG. 5, an opening 130 that penetrates in the direction from the halogen heater 23 to the nip forming member 124 is provided in the stay 125 that is a support member that supports the nip forming member 124. As a result, the portion of the sliding sheet 131 wound around the nip forming member 124 facing the opening 130 (the portion surrounded by the broken line in FIG. 5) is exposed to the halogen heater 23, and the sliding sheet 131 has the same portion. The exposed portion is directly heated by the halogen heater 23. As a result, in comparison with the structure in which the heat of the halogen heater 23 is transmitted to the nip portion by the rotation of the fixing belt, the structure in which the heat conduction effect of the fixing belt itself is transmitted, and the structure through the stay 125 and the nip forming member 124, after the power is turned on, After the printing request, the sliding sheet 131 can be heated and the viscosity of the lubricant can be reduced. Therefore, the fixing belt can be rotated after the power is turned on or the printing is requested. Further, it is possible to suppress the occurrence of paper jam and the thermal deformation of the fixing belt, and it is possible to suppress the occurrence of abnormal images.

  Although the configuration in which the halogen heater directly heats the sliding sheet has been described using the example in which the opening 130 is provided in the stay 125 as shown in FIG. 5, the present invention is not limited to this. For example, as shown in FIG. 6, the nip forming member 124 is also provided with an opening 132 communicating with the opening 130 provided in the stay 125, and the sliding sheet 131 on the side of the nip wound around the nip forming member 124. May be directly heated. In this case, the opening cross-sectional area and the number of the openings 132 are adjusted so that the nip pressing by the pressure roller 22 and the formation of the nip in the nip are less affected.

  FIG. 7 is a diagram showing the configuration of the nip forming member 124, and FIG. 8 is an exploded view thereof. 7 and 8 are front cross-sectional views of the nip forming member 124 as viewed from the sheet conveying direction (the cross-sectional area is substantially the center of the nip portion N in FIG. 1, and the left-right direction in the drawings is the longitudinal direction (pressurization). The axial direction of the roller), the upper side in the figure is the nip side, and the lower side is the stay 125 side.

  The nip forming member 124 shown in FIGS. 7 and 8 includes a base material 241, a nip-side high thermal conductive member 242, a stay-side high thermal conductive member 243, and an internal high thermal conductive member 244. The base material 241 includes a central member 241C, two end members 241T, and two connecting members 241S, as shown in an exploded view in FIG. The base material 241 is generally made of polyether sulfone (PES), polyphenylene sulfide (PPS), liquid crystal polymer (LCP), polyether nitrile (PEN), polyamide imide (PAI), polyether ether ketone (PEEK), or the like. It is possible to suitably use a heat-resistant resin.

  The nip-side high thermal conductive member 242 is a high thermal conductive member arranged so as to cover the surface on the nip side of the nip forming member 124, and is preferably a metal material having high thermal conductivity such as copper (Cu) or aluminum (Al). Can be used for. In the embodiment, copper (Cu) is used. The nip-side high thermal conductive member 242 is a member arranged on the most nip side of the nip forming member 124, and directly transfers heat from the fixing member (fixing belt 21 in the embodiment) (more specifically, in the present example, in the present example). The nip-side high thermal conductive member 242, which is a member that receives the sliding sheet 131) and is a metal material having high thermal conductivity such as copper (Cu) or aluminum (Al), is provided in the width direction of the paper. . As a result, even if the fixing member temperature rises near the end of the paper passing area or in the non-paper passing area when, for example, small size paper is continuously fed, the heat is transferred to the longitudinal direction (paper width direction) by the high thermal conductivity member. ) Can be efficiently transferred to and diffused, and heat is less likely to be accumulated on the surface. Therefore, it is possible to effectively suppress the so-called edge temperature rise during continuous sheet feeding. At the same time, the presence of the low heat conduction portion near the end portion in the longitudinal direction limits the heat escape to the end portion, so that it is possible to suppress the temperature drop at the end portion at the time of fixing start-up. . As described above, in addition to the conventional effects described above, in the configuration in which the opening is provided in the stay serving as the support member, the high thermal conductivity member is easily warmed, so that the temperature of the nip portion can be raised more quickly.

  The nip-side high thermal conductive member 242 of this example has through holes 242a and 242a formed in the vicinity of both ends in the longitudinal direction, and the convex portion 241a provided on the end member 241T of the base material 241 has through holes. It is fitted into 242a. As a result, the entire surface (front surface) of the nip forming member 124 on the nip side is configured to be a flat surface.

  The stay-side high-thermal-conductivity member 243 is a high-thermal-conductivity member arranged on the surface of the nip-forming member 124 on the opposite side to the nip so as to come into contact with the stay 125 (FIG. 1). A metal material having a high thermal conductivity such as Cu) or aluminum (Al) can be preferably used.

  The internal high-thermal-conductivity member 244 is a high-thermal-conductivity member arrange|positioned between the stay side high-thermal-conductivity member 243 and the base material 241 (connection member 241S in this example), and copper (Cu) or aluminum like other high-thermal-conductivity members. A metal material having a high thermal conductivity such as (Al) can be preferably used. The position of the internal high-thermal-conductivity member 244 in the longitudinal direction (direction of the rotation axis of the fixing belt) is arranged so as to correspond to the edge of the sheet when a small size sheet (for example, A5 portrait) is passed, and the internal high-thermal-conductivity member 244 is arranged. Is arranged so that the end portion on the center side (the center side in the longitudinal direction) of the sheet overlaps (overlaps) with the end portion of the small size sheet (for example, A5 vertical) sheet passing area. With the internal high thermal conductive member 244 arranged in this way, even when a small size sheet is continuously passed, even if a temperature rise occurs near the end of the sheet passing area, the heat is efficiently transferred to the stay side high thermal conductive member. Then, the heat is diffused and absorbed in the longitudinal direction (paper width direction) and the thickness direction of the nip forming member 124.

  In order to arrange the internal high thermal conductivity member 244, the thickness of the base material 241 (the vertical direction in the figure) is thinned at that portion, and in the illustrated example, the thickness of the connection member 241S and the internal high thermal conductivity member 244 overlapped. Is equal to the central member 241C of the base material.

  By the way, as the thickness of each of the high thermal conductive members is larger (thicker), the effect of preventing the temperature rise at the end portion is more significant, but if the thickness is too thick, warming-up is delayed and energy efficiency is reduced. Therefore, in the present embodiment, the stay-side high thermal conductive member 243 has a thickness of 2 [mm], the internal high thermal conductive member 244 has a thickness of 1.5 [mm], and the nip-side high thermal conductive member 242 has a thickness of 0. It is set to 6 [mm]. Further, in the base material 241, the thickness of the connecting member 241S is 1 [mm], and the thickness of the central member 241C is 2.5 [thickness of the connecting member 241S+the thickness of the internal high thermal conductive member 244]. mm]. The thickness of the convex portion 241a of the base material (thickness of only the convex portion) is 0.6 mm, which is the same as the thickness of the nip-side high thermal conductive member 242.

  Further, the nip-side high thermal conductive member 242 has a length of 344 [mm] in the axial direction (longitudinal direction=paper width direction=horizontal direction in the drawing) and has a width (8.5 (mm) from the end portion). A through hole 242a having an axial length of 7.0 [mm] is provided. The center-side end of the through hole 242a, that is, the center-side end of the convex portion 241a of the base material 241 is located outside (the end side) of the outermost end of the sheet-passing area of the maximum size that allows sheet-passing. It is provided to do.

  7 and 8 are schematic diagrams for explaining the configuration of the nip forming member 124. FIG. 9 shows a specific shape of the nip forming member 124. FIG. 10 is an exploded view thereof.

  In the configurations of FIGS. 7 and 8, the base material 241 is divided into a plurality of members, and the internal high thermal conductivity member 244 is provided. However, the base material and each high thermal conductivity member are divided respectively. Alternatively, a plate-shaped member may be used, or an integral member having a convex portion and a concave portion may be used. 7 to 10, the thickness direction is exaggerated with respect to the length direction, and the dimensions of each member including the length direction are different from those of the actual member as it is. There is.

  In the configuration examples shown in FIGS. 9 and 10, the base material 241 is configured by one member, and has a shape having a convex portion 241a and a concave portion 241b. Further, the internal high thermal conductivity member 244 in FIG. 9 is omitted, and the stay-side high thermal conductivity member 243 having one protrusion 243a corresponding thereto is used. The convex portion 243a has a shape that fits exactly into the concave portion 241b. The nip-side high thermal conductive member 242 is the same as that in FIGS. 7 and 8. The nip forming member 124 in which the respective members are combined has the completely same outer shape as the nip forming member 124 of FIGS. 7 and 8. The action of each member is also the same.

  In the fixing device of the present embodiment configured as described above, the nip forming member 124 is, as shown in FIG. 9, a first high thermal conductive layer (heat-uniforming layer) from the nip side (nip-side heat-uniforming layer=first layer). It has a three-layer structure including a first heat equalizing layer), a base material layer, and a second high thermal conductive layer (heat equalizing layer) (stay-side heat equalizing layer=second heat equalizing layer).

  Most of the nip-side high thermal conductive layer is composed of the nip-side high thermal conductive member 242 (a convex portion 241a of the base material 241 is fitted in a part thereof), and has a high thermal conductivity (than the base material layer). Is also a layer having a high thermal conductivity, and is a portion provided on the outermost layer (nip side) of the nip forming member 124 to equalize the heat from the fixing nip (fixing member) in the longitudinal direction (axial direction). Soaking layer).

  Here, the nip-side high thermal conductive layer has a non-uniform thermal conductivity in the longitudinal direction (axial direction) because the convex portion 241a of the base material is fitted in a part of the nip side high thermal conductive layer. ) Has a structure with a low heat conduction part near the end. With such a configuration, when the fixing operation is executed, even when the small size paper is continuously fed, even if the temperature rises near the end of the paper passing area or in the non-paper passing area, Is efficiently moved and diffused in the longitudinal direction (paper width direction) by the heat equalizing layer, and heat is less likely to be accumulated on the surface. Therefore, it is possible to effectively suppress the so-called edge temperature rise during continuous sheet feeding. At the same time, the presence of the low heat conduction part near the end in the longitudinal direction (axial direction) limits the heat escape to the end (the end of the paper passing area), and the end at the time of fixing start-up. It is possible to suppress the temperature drop in the section.

  FIG. 11 is a trihedral view showing a specific shape of the nip forming member 124. 11A is a perspective view, FIG. 11B is a side view seen from the axial direction, and FIG. 11C is a plan view seen from the nip side. As described above, in the illustrated example, the nip-side high thermal conductive member 242 has a length of 344 [mm] in the axial direction (longitudinal direction=paper width direction) and a width of 8.5 [mm] from the end. A through hole 242a (FIG. 8) of (axial length) 7.0 [mm] is provided. The center-side end of the through hole 242a, that is, the center-side end of the convex portion 241a of the base material 241 is located outside (the end side) of the outermost end of the sheet-passing area of the maximum size that allows sheet-passing. It is provided to do.

  In the present embodiment described above, the through hole 242a is provided in the nip-side high-thermal-conductivity member 242, which is the outermost layer (nip side) of the nip-forming member 124, so that the longitudinal direction (axial direction) of the high-thermal-conductivity layer is increased. ), the thermal conductivity in (1) is not uniform (nonuniform). However, the configuration in which the thermal conductivity in the longitudinal direction (axial direction) of the high thermal conductive layer is not uniform is not limited to this, and an appropriate configuration can be adopted.

  Note that the relationship between the base material 241 and the nip-side high thermal conductive member 242 may be a configuration having a high thermal conductive member in the nip portion as shown in FIG. 11B, but a modified example of the nip forming member 124. As shown in FIG. 12, the temperature of the nip portion is further improved by providing the high thermal conductive member 245 on the opposite side of the nip forming member 124, which is a portion receiving the heat of the halogen heater through the opening of the stay. Can be raised quickly.

The high thermal conductivity member 245 is made of a material having a higher thermal conductivity than the base material 241. For example, the high thermal conductive member 245 includes carbon nanotubes (thermal conductivity: 3000 to 5500 [W/mK]), graphite sheets (thermal conductivity: 700 to 1750 [W/mK]), silver (thermal conductivity: 420 [ W/mK]), copper (thermal conductivity: 398 [W/mK]), aluminum (thermal conductivity: 236 [W/mK]), SECC (electrogalvanized steel), or the like. The thermal conductivity of the high thermal conductivity member 245 is preferably 236 [W/mK] or more. On the other hand, the base material 241 is made of a resin material having high heat resistance, such as polyether sulfone (PES), polyphenylene sulfide (PPS), liquid crystal polymer (LCP), polyether nitrile (PEN), polyamide imide (PAI), polyether. It is formed of ether ketone (PEEK) or the like.
In addition, although the example in which the high heat transfer member is used as the nip forming member has been described, the present invention is not limited to this, and a heat pipe may be used instead of the high heat transfer member.

  Further, the opening 130 of the stay does not have to be opened perpendicularly to the nip forming member, but may be oblique to the thickness direction as shown in FIG. In that case, by providing the reflecting member inside the opening, heat can be mutually amplified by the reflecting member while passing through the inside of the opening, so that there is an energy saving effect.

  As a heat transfer means for transferring the radiant heat from the halogen heater to the sliding sheet in the nip part, a metal member having a good heat transfer property is provided in addition to the opening part provided in the stay or the nip forming member as shown in FIG. Or a heat pipe may be provided. As a result, the radiant heat is transferred to the sliding sheet in the nip portion in the order of air and heat transfer means, so that the lubricant temperature held by the sliding sheet quickly rises even if the fixing belt does not rotate, and the fixing belt The viscosity is such that slip and thermal deformation do not occur. In addition, it is effective to provide the heat transfer means using the openings or the metal at several locations in the axial direction to warm the entire lubricant, and the opening cross-section of the openings may be round or square (FIG. 14). good. Further, as shown in FIG. 14A, the openings have a plurality of rows in the axial direction, so that it is possible to secure the strength of the stay while improving heat conduction. In addition, as shown in FIGS. 14B and 14C, when the openings are arranged in a zigzag pattern, uneven heating can be suppressed.

  Further, since the sliding sheet slides in a high temperature environment near the halogen heater, the lubricant held by the sliding sheet is preferably fluorine grease or silicone oil having a high heat resistance temperature. Fluorine grease is a gel-like lubricant in which a thickener is dispersed in a base oil, and has a viscosity higher than that of oil, so it is effective as a countermeasure against outflow from sliding parts. There is Knox lube etc. Since fluorine grease has a high viscosity, it has a characteristic that the viscous torque becomes large. When high speed fluctuations such as slip of the fixing belt are required, it is appropriate to use silicone oil with high heat resistance and low viscosity, as with fluorine grease, such as Shin-Etsu Silicone KF-968-100CS. use.

FIG. 15 is a perspective view of the nip forming member and its peripheral members. FIG. 16 is a side view when the sliding sheet 131 is wound around the nip forming member 124.
As shown in FIGS. 15 and 16, a fluorine-based sliding sheet 131 having good slidability is wound around the nip forming member 124. Specifically, the upper hole of the sliding sheet 131 is hooked on the lower protrusion of the nip forming member 124 and wound as shown by the arrow in FIG. Hook. Then, the sliding sheet 131 is screwed to the nip forming member 124 by the fixing member 133 with the screw 134. By thus winding the sliding sheet 131 around the nip forming member 124, the sliding load between the nip forming member 124 and the inner peripheral surface of the fixing belt is reduced. As a result, it is possible to suppress the occurrence of a slip phenomenon in which the paper is not fed at the linear velocity in the nip portion N due to the increase in the frictional resistance due to the abrasion between the nip forming member 124 and the inner peripheral surface of the fixing belt with the passage of time and the increase in the torque. can do.

  In addition, in the sliding sheet, the area of the yarn that appears on the front surface differs from that on the back surface, depending on the weaving method of the sheet-shaped fibers. The plain weave has the same area ratio on the surface of the warp and weft, but the warp and the satin weave have a larger area on the surface than the weft. When knitting two or more kinds of fibers, the area of the friction surface is increased by increasing the area of the fluororesin, and the area of the back surface is increased by increasing the area of the resin with high strength or the resin with high oil content. A sheet with good friction and wear characteristics and high strength. TOYOFLON manufactured by Toray is a resin sheet in which two fibers of polytetrafluoroethylene (PTFE) and polyphenylene sulfide (PPS) are woven, and has an effect of suppressing an increase in torque over time.

FIG. 17 is a perspective view when the sliding sheet 131 having the opening 131 a is wound around the nip forming member 124.
As shown in FIG. 17, an opening 131a is also provided in the sliding sheet 131 so as to correspond to the opening of the stay and the opening of the nip forming member. Thereby, the heat of the halogen heater can be directly transferred to the sliding sheet 131 in the nip portion. Therefore, the viscosity of the lubricant held by the sliding sheet can be lowered almost at the same time as the rotation of the fixing belt, and it is possible to suppress the occurrence of the abnormal image and the jam of the sheet due to the conventional slip.

  Further, the base member of the fixing belt may not have good slidability with the material, and it is appropriate to apply a ceramic-based or fluorine-based coating to reduce the frictional load on the surface. Fluorine-based PTFE and PFA coatings are often used as fluorine coatings that are generally slidable because they have low reactivity with other materials and have high heat resistance. For example, the fluorine coating of Daikin Industries in Table 1 below is used. There are PFA and PTFE grades depending on the temperature and application. The ceramic-based coating has a higher hardness than the fluorine coating and is less likely to wear, and is effective when it is desired to avoid an increase in the viscosity of the lubricant due to abrasion of the coating. Further, a fluorine-based coating has better adhesion to a metal than a resin. For example, when heat resistance of the resin is insufficient or when heat transfer in the axial direction is desired to be improved, it is possible to coat a metal such as SUS. Optimal. Further, as shown in FIG. 17, screws, screw fastening parts, etc. are not required for the peripheral structure of the nip forming member, which is conventionally made of resin, so that the number of parts can be greatly reduced and the cost can be reduced.

What has been described above is an example, and the present invention has a unique effect in each of the following aspects.
(Aspect A)
A rotatable endless fixing member such as the fixing belt 21, a pressure rotator such as a pressure roller 22 that contacts and pressurizes the outer peripheral surface of the fixing member, and an inner peripheral surface side of the fixing member. Nip forming member 124 that forms a nip portion with the pressure rotating body via the fixing member, a heating element such as a halogen heater 23 that heats the inner peripheral surface of the fixing member, and a slide that holds a lubricant. A lubricant holding member such as a moving sheet 131, the lubricant holding member is interposed between the nip forming member and the inner peripheral surface of the fixing member, and a recording material is passed through the nip portion to form an image. In the fixing device 20 for fixing the toner to the recording material, a heat transfer unit such as an opening 130 that transfers the heat of the heating element to the lubricant holding member in the nip portion in a state where the fixing member is stopped is provided. Is to
In the conventional configuration, the nip forming member is interposed between the heating element and the lubricant holding member to prevent the heat of the heating element from being transferred to the lubricant holding member, so that the heating element can prevent the heat of the heating element from being transmitted to the lubricant holding member. Unless the heated portion of the heated fixing member reaches the nip portion as the fixing member rotates, the heat of the heating element cannot be transmitted to the lubricant holding member. On the other hand, according to this aspect, even if there is a nip forming member, the heat of the heating element is retained in the nip portion by the heat transfer means without rotating the fixing member immediately after driving the heating element. It is transmitted to members. This makes it possible to reduce the viscosity of the lubricant held by the lubricant holding member so that the fixing member can rotate after the power is turned on or after a printing request. Therefore, the fixing member can be rotated after the power is turned on or the printing is requested.

(Aspect B)
In (Aspect A), a support body such as a stay 125 that supports the nip forming member is provided, and as the heat transfer means, a space in which the heat generating body exists in the support body and a sheet wound around the nip forming member. The opening 130 is provided so as to communicate with the space in which the lubricant holding member is present.
According to this aspect, the heat of the heating element is transmitted to the sheet-shaped lubricant holding member wound around the nip forming member through the opening of the support after the power is turned on or the printing is requested. The lubricant held by the lubricant holding member rises to a temperature at which the fixing member becomes viscous so that the fixing member can rotate. Therefore, the fixing member can be rotated after the power is turned on or the printing is requested.

(Aspect C)
In (Aspect B), the nip forming member is provided with an opening 132 that is connected to the opening provided in the support, and passes through the opening of the support and the opening of the nip forming member, The lubricant holding member is heated by the heating element.
According to this aspect, the heat of the heating element is transmitted to the sheet-shaped lubricant holding member wound around the nip forming member through the opening of the support and the opening of the nip forming member after the power is turned on or the printing is requested. The lubricant held by the lubricant holding member rises to a temperature at which the fixing member becomes viscous so that the fixing member can rotate. Therefore, the fixing member can be rotated after the power is turned on or the printing is requested.

(Aspect D)
In (Aspect A) to (Aspect C), the nip forming member is a base material 241 and a high thermal conductivity which is a nip-side high thermal conductivity member 242 provided on the fixing member side and having a higher thermal conductivity than the base material. And a member.
According to this aspect, since the nip forming member includes the high thermal conductive member, the nip portion can be easily warmed up. Therefore, the warm-up time and the first print time can be shortened.

(Aspect E)
In (Aspect B), the openings of the support body are formed in a plurality of rows in the rotation axis direction of the pressing rotary body of the support body.
According to this aspect, while the strength of the support is ensured, the openings of the support are relatively large, so that the lubricant holding member can be efficiently heated.

(Aspect F)
In (Aspect A) to (Aspect E), the lubricant holding member is formed of a fluorine-based fiber.
According to this aspect, the friction and wear characteristics are excellent, the lubricant can be impregnated, and the outflow of the lubricant can be suppressed.

(Aspect G)
An image carrier such as the photosensitive drum 120, a toner image forming unit such as a developing device 40 that forms a toner image on the image carrier, and a transfer device that transfers the toner image from the image carrier onto a recording medium. In the image forming apparatus 1 including a transfer unit such as 71 and a fixing unit such as a fixing device 20 that fixes the toner image transferred onto the recording medium onto the recording medium, the fixing unit may be (Aspect A). The fixing device according to any one of (1) to (A) is used.
According to this aspect, the lubricant held by the lubricant holding member can be heated after the power is turned on or after printing is requested, and the lubricating performance of the lubricant can be improved. Therefore, it is possible to suppress the rotation failure of the fixing member that has occurred without lowering the viscosity of the lubricant, and it is possible to perform good image formation.

1 Image Forming Device 3 Feeding Roller 4 Registration Roller Pair 5 Secondary Transfer Roller 7 Paper Ejection Roller 8 Optical Writing Device 9 Toner Bottle 10 Transfer Belt Unit 11 Intermediate Transfer Belt 12 Primary Transfer Roller 13 Transfer Belt Cleaning Device 17 Paper Ejection Tray 20 Fixing Device 21 Fixing Belt 22 Pressure Roller 22a Core Bar 22b Elastic Layer 22c Release Layer 23 Halogen Heater 24 Nip Forming Member 25 Reflecting Member 26 Separation Plate 30 Charging Device 40 Developing Device 50 Cleaning Device 61 Paper Feeding Device 71 Transfer Device 72 driving roller 73 driven roller 100 fixing belt 120 photoconductor drum 124 nip forming member 125 stay 130 opening 131 sliding sheet 132 opening 133 fixing member 134 screw 200 metal heat conductor 220 fixing device 241 base material 242 nip-side high thermal conductivity Member 243 High heat conducting member on stay side 244 High heat conducting member inside 245 High heat conducting member 300 Heat source 400 Pressure roller

JP, 2013-152397, A

Claims (6)

A rotatable endless fixing member, a pressure rotator that contacts and pressurizes the outer peripheral surface of the fixing member, and a pressure rotating member that is disposed on the inner peripheral surface side of the fixing member and through the fixing member. A nip forming member that forms a nip portion with the body, a heating element that heats the inner peripheral surface of the fixing member, and a lubricant holding member that holds a lubricant, and the lubricant holding member is formed into the nip. In a fixing device which is interposed between a member and an inner peripheral surface of the fixing member, a recording material is passed through the nip portion to fix an image on the recording material,
A support for supporting the nip forming member,
As a heat transfer means for transmitting the heat of the heating element to the lubricant holding member in a state where the fixing member is stopped, a sheet shape wound around the space where the heating element exists and the nip forming member on the support. 2. A fixing device comprising an opening communicating with the space in which the lubricant holding member exists . The fixing device 請 Motomeko 1,
An opening is provided in the nip forming member so as to be connected to the opening provided in the support, and the lubrication is performed by the heating element through the opening of the support and the opening of the nip forming member. A fixing device characterized by heating an agent holding member. The fixing device according to claim 1 or 2 ,
The fixing device is characterized in that the nip forming member is composed of a base material and a high thermal conductive member which is provided on the fixing member side and has a higher thermal conductivity than the base material. The fixing device according to claim 1 ,
The fixing device is characterized in that the openings of the support body are formed in a plurality of rows in the rotation axis direction of the pressure rotating body of the support body. The fixing device according to any one of claims 1 to 4 ,
The fixing device is characterized in that the lubricant holding member is formed of a fluorine-based fiber. Image carrier, toner image forming means for forming a toner image on the image carrier, transfer means for transferring the toner image from the image carrier to a recording medium, and toner transferred on the recording medium In an image forming apparatus including a fixing unit that fixes an image on the recording medium,
As the fixing means, the image forming apparatus characterized by using the fixing device according to any one of claims 1 to 5.

Images