JP2017207535A - Fixing device and image forming apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To make it possible to rotate a fixing member after the power is turned on and after a print request is received.SOLUTION: There is provided a fixing device 20 comprising: an endless rotatable fixing member, such as a fixing belt 21; a pressure rotating body, such as a pressure roller 22 that is in contact with the outer peripheral surface of the fixing member to apply pressure to the fixing member; a nip forming member 124 that is arranged on the inner peripheral surface side of the fixing member to form a nip with the pressure rotating body with the fixing member therebetween; a heating element, such as a halogen heater 23 that heats the inner peripheral surface of the fixing member; and a lubricant holding member, such as a slide sheet 131 that holds a lubricant, the fixing device interposing the lubricant holding member between the nip forming member and the inner peripheral surface of the fixing member and passing a recording material through the nip part to fix an image to the recording material. The fixing device includes heat transmission means, such as an opening part 130 that transmits heat from the heating element to the lubricant holding member while the fixing member is stopped.SELECTED DRAWING: Figure 1

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 nip forming member is formed by pressing a pressure roller, which is a pressure rotator, with the fixing member sandwiched therebetween, There is known a fixing device that passes a recording material through a nip portion and fixes an image on the recording material.

  For example, Patent Document 1 discloses such a fixing device, in which the outer peripheral surface of a fixing belt as a fixing member is in contact with the outer peripheral surface of a pressure roller by a fixing member as a nip forming member supported by a reinforcing member. 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. Furthermore, 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 upstream of the nip portion in the fixing belt moving direction. Then, the heated portion of the fixing belt reaches the nip portion as the fixing belt rotates, whereby the sheet-like member is heated and the viscosity of the lubricant held by the sheet-like member is lowered. Thereby, it is said that the sliding performance of the fixing belt with respect to the sheet-like member can be improved at the nip portion.

Usually, 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-like member, and the heat of the halogen heater is prevented from being transmitted to the sheet-like member. Therefore, the sheet-like 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 after the power is turned on or after printing is requested. The viscosity remains high. As a result, the static frictional force between the sheet-like 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 therebetween. If it exceeds the static frictional force with the outer peripheral surface, the fixing belt may not rotate.

  In order to solve the above-described 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 forms and forms a nip portion with the pressure rotator via 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 the recording material is passed through the nip portion to fix the image on the recording material. And a heat transfer means for transferring heat of the heating element to the lubricant holding member in a state where the fixing member is stopped.

  According to the present invention, it is possible to obtain a specific effect that the fixing member can be rotated after the power is turned on or after a print request.

FIG. 3 is a cross-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. 6 is a cross-sectional view illustrating an example of a conventional fixing device 220. FIG. 3 is a cross-sectional view illustrating an example of a fixing device 20 according to the present embodiment. FIG. 6 is a cross-sectional view illustrating another example of the fixing device 20 according to the present embodiment. FIG. 3 is a cross-sectional view showing a configuration of a nip forming member 124. FIG. 8 is an exploded cross-sectional view of the nip forming member 124 of FIG. 7. Sectional drawing which shows another structure of the nip formation member 124. FIG. FIG. 10 is an exploded cross-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, (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 formation member 124. FIG. Sectional drawing which shows another example of the opening part 130. FIG. The top view which shows the example of an arrangement | sequence of the opening part 130. FIG. The perspective view of a nip formation member and its peripheral member. The side view when the sliding sheet 131 is wound around the nip forming member 124. The perspective view when the sliding sheet | seat 131 which has the opening part 131a is wound around the nip formation member 124. FIG.

  Embodiments of the present invention will be described below with reference to the drawings. In each of the drawings for explaining the embodiments of the present invention, constituent elements such as members and components having the same function or shape are described once by giving the same reference numerals as much as possible. Then, the explanation is omitted.

FIG. 2 is a schematic configuration diagram of the image forming apparatus 1 according to the present embodiment.
An image forming apparatus 1 shown in FIG. 2 is a tandem type color laser printer, and an image forming section (four image forming sections in the example shown in FIG. 2) that forms a plurality of color images at the center of the apparatus main body. An image station is provided.

  The plurality of image forming units are juxtaposed along the extending direction of the intermediate transfer belt 11 as an endless belt-like intermediate transfer member. 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 accommodated. .

  In FIG. 2, the image forming apparatus 1 includes a plurality of photosensitive drums 120Y, 120C, 120M, and 120Bk as image bearing members corresponding to colors separated into yellow, cyan, magenta, and black, respectively. ing.

  A toner image, which is a visible image of each color, formed on each photoconductor drum 120Y, 120C, 120M, and 120Bk is an intermediate transfer that can move in the direction of arrow A1 while facing each photoconductor drum 120Y, 120C, 120M, and 120Bk. A 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. Thereafter, the toner images of the respective colors superimposed 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.

  Various devices for performing image forming processing according to the rotation of the photosensitive drum 120 are arranged around the photosensitive drums 120Y, 120C, 120M, and 120Bk.

  Here, the photosensitive drum 120Bk that performs black image formation will be described. Around the photosensitive drum 120Bk, there are a charging device 30Bk, a developing device 40Bk, a primary transfer roller 12Bk as a primary transfer unit, and a cleaning device 50Bk that perform image forming processing along the rotation direction of the photosensitive drum 120Bk. Has been placed. For writing of the electrostatic latent image performed on the charged photosensitive drum 120Bk, the optical writing device 8 is used as an exposure unit that exposes the surface of the photosensitive 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 photosensitive drums 120Y, 120C, 120M, and 120Bk with writing light (laser light) Lb based on the image data, and statically irradiates the photosensitive drums 120Y, 120C, 120M, and 120Bk. An electrostatic latent image is formed.

  In the superimposing transfer to the intermediate transfer belt 11, the visible image (toner image) formed on the photosensitive drums 120Y, 120C, 120M, and 120Bk is transferred to the intermediate transfer belt in the process in which the intermediate transfer belt 11 moves in the A1 direction in FIG. 11 is performed so as to be transferred to the same position.

  More specifically, the primary transfer bias is applied to each of the plurality of primary transfer rollers 12Y, 12C, 12M, and 12Bk disposed to face the respective photosensitive drums 120Y, 120C, 120M, and 120Bk with the intermediate transfer belt 11 interposed therebetween. Applied. By the primary transfer rollers 12Y, 12C, 12M, and 12Bk to which the primary transfer bias is applied, the toner images formed on the respective photosensitive drums 120Y, 120C, 120M, and 120Bk are superimposed with the timing shifted in the intermediate transfer belt rotation direction. Transcribed.

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

  Each primary transfer roller 12Y, 12C, 12M, 12Bk is connected to a power source. A primary transfer bias consisting of at least one of a predetermined direct current voltage (DC voltage) and alternating current voltage (AC voltage) is applied to each primary transfer roller 12Y, 12C, 12M, 12Bk by this power source. Yes.

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

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

  The transfer belt unit 10 includes a plurality of belt support members such as an intermediate transfer belt 11 and a plurality of primary transfer rollers 12Y, 12C, 12M, and 12Bk, as well as a driving roller 72 and a driven roller 73 around which the intermediate transfer belt 11 is wound. It has. By driving the drive roller 72 to rotate, the intermediate transfer belt 11 rotates in the direction indicated by the 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 unit for the intermediate transfer belt 11, the driven roller 73 is provided with an urging unit 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. Further, the secondary transfer roller 5 sandwiches the intermediate transfer belt 11 with a driving roller 72 that also functions as a secondary transfer backup roller, thereby forming a secondary transfer nip.

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

  The transfer belt cleaning device 13 is disposed so as to face the driven roller 73 with the intermediate transfer belt 11 interposed therebetween, and cleans the surface of the intermediate transfer belt 11. In the example shown in FIG. 2, the transfer belt cleaning device 13 includes a cleaning brush and a cleaning blade disposed so as to contact the intermediate transfer belt 11. A 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 accommodated, a registration roller pair 4 as recording material feeding means, and a sheet leading edge sensor as recording material leading edge detection means. Is provided.

  The sheet feeding device 61 is disposed at the lower part of the main body of the image forming apparatus 1 and includes a feeding roller 3 as a recording material feeding unit that comes into contact with the upper surface of the uppermost sheet P. The feed roller 3 is driven to rotate counterclockwise in FIG. 2 so that the uppermost sheet P is fed toward the registration roller pair 4.

  In the image forming apparatus main body, a paper transport path is provided for discharging 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 sheet P to the secondary transfer nip is disposed upstream of the position of the secondary transfer roller 5 in the sheet conveyance path in the sheet conveyance direction.

  The registration roller pair 4 and the secondary transfer roller 5 are in contact with the secondary transfer roller 5 at a predetermined timing in accordance with the toner image formation timing of the paper P conveyed from the paper feeding device 61 by the image station including the plurality of image forming units. It is fed out toward the secondary transfer nip with 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 the recording material includes, in addition to plain paper, thick paper, postcard, envelope, thin paper, coated paper (coated paper, art paper, etc.), tracing paper, OHP sheet, recording sheet, and the like. . In addition to the paper feeding device 61, a manual paper feed 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 paper P on which the toner image is transferred, a paper discharge roller 7 as a recording material discharging unit, and a recording material stacking unit. The sheet discharge tray 17 is provided. 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 disposed at the upper part of the main body of the image forming apparatus 1 and stacks and stores the paper P discharged to the outside of the main body of the image forming apparatus 1 by the paper discharge roller 7.

  Further, the image forming apparatus 1 includes toner bottles 9Y, 9C, 9M, and 9Bk as a plurality of toner containers. Each of the plurality of toner bottles 9Y, 9C, 9M, and 9Bk is filled with toner of each color of yellow, cyan, magenta, and black, and the plurality of toner bottles 9Y, 9C, 9M, and 9Bk are provided above the image forming apparatus main body and below the paper discharge tray 17. It is detachably attached to each bottle housing part.

  A replenishment path is provided between each toner bottle 9Y, 9C, 9M, 9Bk and each developing device 40Y, 40C, 40M, 40Bk. The toner is supplied from the toner bottles 9Y, 9C, 9M, and 9Bk to the corresponding developing devices 40Y, 40C, 40M, and 40Bk through the 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 disposed so as to contact the intermediate transfer belt 11.

  The cleaning brush and the cleaning blade scrape and remove foreign matters such as residual toner on the intermediate transfer belt 11 to clean the intermediate transfer belt 11. The transfer belt cleaning device 13 has a discharge means 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 photosensitive drums 120Y, 120C, 120M, and 120Bk in each image forming unit are rotationally driven clockwise in FIG. The surfaces of the photosensitive drums 120Y, 120C, 120M, and 120Bk are uniformly charged with a predetermined polarity by the charging devices 30Y, 30C, 30M, and 30Bk.

  The surface of each charged photoconductive drum 120Y, 120C, 120M, and 120Bk is irradiated with laser light from the optical writing device 8, respectively, and the surface of each photoconductive drum 120Y, 120C, 120M, and 120Bk is electrostatic latent. An image is formed. At this time, the image information exposed on each of the photosensitive drums 120Y, 120C, 120M, and 120Bk is single-color image information obtained by separating a desired full-color image into color information of yellow, magenta, cyan, and black.

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

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

  Thereafter, the toner images on the photosensitive 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 full color is transferred onto the surface of the intermediate transfer belt 11. The toner image is carried.

  Further, the toner on each of the photosensitive 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. Thereafter, the surface of each of the photosensitive drums 120Y, 120C, 120M, and 120Bk is neutralized by the static eliminator, 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 paper P is sent from the paper feeding device 61 to the conveyance path. The sheet P sent to the conveyance path is timed by the registration roller pair 4 and sent to the secondary transfer nip between the drive roller 72 and the secondary transfer roller 5 that also functions as a secondary transfer backup roller. It is done. At this time, a transfer voltage having a polarity opposite to the toner charge 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. .

  Thereafter, 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 images are transferred onto the paper P at once.

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

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

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

  Examples of the fixing method used in the image forming apparatus include 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 as a pressure rotator that are in contact with each other while facing each other with a sheet conveyance path interposed therebetween are used. In this system, the toner image is melted and penetrated into the sheet by the action of heat from a heat source provided in the fixing roller and pressure corresponding to the pressure applied from the pressure roller. The phenomenon that the toner image melts and penetrates the paper is the same in the fixing method having the following configuration.

  In the belt fixing system, a fixing belt serving as a good heat conductor, a pressure roller, a roller equipped with the belt, and a heating source for the belt are used instead of the fixing roller.

  In the film fixing system, a fixing belt serving as a heat good conductor, a pressure roller, a roller equipped with the belt, and a heating source for the belt are used instead of the fixing roller.

  In the electromagnetic induction heating and fixing method, a configuration in which an electromagnetic induction coil that enhances heat generation efficiency is provided on the heating member is used.

The fixing system has the following required issues.
It is to reduce the warm-up time, and further to reduce the first print time. The warm-up time is a time required from a normal temperature state to a predetermined printable temperature (reload temperature) such as when the power is turned on. The first print time is a time required from when a print request is received to when a print operation is performed through a print preparation and paper discharge is completed.

In the fixing device, fixing failure may occur for the following reason.
The image forming apparatus is an apparatus that can perform high-speed processing. When the number of fixed sheets per unit time, that is, the number of sheets passing through the fixing device is increased by high-speed processing, the amount of heat supplied to the sheet P that moves at high speed must also be increased. This is because the amount of heat necessary for fixing is given to the paper as the time for the paper P to pass through the fixing device becomes shorter.

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

  In addition, as the speed of image forming apparatuses increases, the number of sheets passed per unit time increases and the required heat quantity increases, so the so-called temperature drop, which is a shortage of heat quantity especially at the beginning of continuous printing, may be a problem. There is a problem that fixing failure occurs when the speed is increased.

  On the other hand, in addition to the above-described fixing methods, 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, since the heat capacity and the size can be reduced as compared with the belt-type fixing device, it is possible to rise to a predetermined temperature and shorten the first print time, but there are the following problems.

  In other words, the surf fixing method is not heated in any part other than the local area, so that there is a problem that the fixing belt is in the coldest state at the entrance of the nip sheet and the like, and fixing failure is likely to occur. In particular, in a high-speed machine, there is a problem that a fixing failure is more likely to occur because the fixing belt rotates quickly and the heat radiation of the belt outside the nip increases.

  Therefore, in order to cope with such a problem, there has been proposed a fixing device in which a fixing belt can be obtained in a configuration using a fixing belt, even if it is mounted on a high-production image forming apparatus.

In the fixing device, the configuration shown in FIG. 3 is used.
The fixing belt 100, the pipe-shaped metal heat conductor 200 disposed inside the fixing belt 100, the heat source 300 disposed in the metal heat conductor 200, and the metal heat conductor 200 via the fixing belt 100. And a pressure roller 400 that forms a nip portion N.

  The rotation of the pressure roller 400 causes the fixing belt 100 to rotate and move in the circumferential direction. At this time, the metal heat conductor 200 guides the movement of the fixing belt 100. In addition, the fixing belt 100 is heated by the heat source 300 in the metal heat conductor 200 via the metal heat conductor 200, so that the entire fixing belt 100 can be heated. This makes it possible to shorten the first print time from the heating standby time and to solve 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 embodiment will be described with reference to FIG. FIG. 1 is a cross-sectional view of a fixing device 20 according to the present embodiment.

  The fixing device 20 includes a fixing belt 21 as a fixing member, which is a surface endless moving body having a hollow inside, and a pressure roller 22 including an opposing rotating body that is provided so as to be able to rotate facing the fixing belt 21. Yes.

  Inside the fixing belt 21, there are provided a halogen heater 23 as a heating element for heating the fixing belt 21, a pressure roller 22 opposed via the fixing belt 21, and a nip forming member 124 for forming a nip portion N. Yes. Further, the reflection member 25 that reflects the radiant heat from the halogen heater 23 to the inner peripheral surface of the fixing belt 21, the separation plate 26 that separates the paper P from the fixing belt 21, and the pressure roller 22 that pressurizes the fixing belt 21. Pressure means are also provided.

  In addition, flanges as belt holding members are inserted into 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, it has a release layer on the outer peripheral side formed of tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer (PFA) or polytetrafluoroethylene (PTFE), and has a release property so that toner does not adhere. Yes. Further, an elastic layer made of a rubber material such as silicone rubber may be interposed between the base material and the release layer.

  In the case where there is no elastic layer, the heat capacity is reduced and the fixability is improved. However, when the unfixed toner is crushed and fixed, minute irregularities on the surface of the belt are transferred to the image, and there is a possibility that a scum-like mark remains on the solid portion of the image. In order to improve this, it is desirable to provide an elastic layer having a thickness of 100 [μm] or more. By providing an elastic layer having a thickness of 100 [μm] or more, minute irregularities can be absorbed by the elastic deformation of the elastic layer, so that it is possible to suppress the leaving of a crusty 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, fluorine rubber, 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 toward the fixing belt 21 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 the place where the pressure roller 22 and the fixing belt 21 are in pressure contact, 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 image forming apparatus main body. When the pressure roller 22 is driven to rotate, the driving force is transmitted to the fixing belt 21 at the nip portion N, and the fixing belt 21 is driven to rotate (follow).

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

  The elastic layer 22b may be solid rubber, but when there is no heat source inside the pressure roller 22, sponge rubber may be used. Sponge rubber is more preferable because heat insulation is enhanced and heat of the fixing belt 21 is less likely to be taken away. In addition, the fixing belt 21 and the pressure roller 22 are not limited to being in pressure contact with each other, and may be configured to simply contact without pressing.

  In the fixing device 20 shown in FIG. 1, the fixing belt 21 is directly heated by 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 so that power is supplied from a power source, which is a power supply unit provided in the main body of the image forming apparatus 1, output is controlled, and heat is generated.

  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, for example, the detection result of the surface temperature of the fixing belt 21 by the temperature sensor. By such output control of the halogen heater 23, the temperature of the fixing belt 21 can be set to a desired temperature (fixing temperature).

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

  Instead of the temperature sensor that detects the temperature of the fixing belt 21, a temperature sensor that detects the temperature of the pressure roller 22 is provided, and the temperature of the fixing belt 21 is predicted based on the temperature detected by the temperature sensor. Also good.

  The surface of the nip forming member 124 facing the fixing belt 21 is slidably coded. The nip forming member 124 is disposed in a longitudinal shape over 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 applied by the pressure roller 22. In the present embodiment, the shape of the nip portion N is flat, but may be a concave shape or other shapes. When the shape of the nip portion N is concave, the discharge direction of the leading edge 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 greatly improves heat resistance as compared with the case of using a resin member. As a result, the nip forming member 124 is prevented from being deformed by heat in the toner fixing temperature range, and a stable state of the nip portion N is secured to stabilize the output image quality.

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

  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 a direction from the halogen heater 23 toward the nip forming member 124. Thereby, a portion of the sliding sheet 131 that is wound around the nip forming member 124 is exposed to the halogen heater 23, and the exposed portion of the sliding sheet 131 is directly heated by the halogen heater 23. The For example, a plurality of openings 130 are provided in the longitudinal direction of the stay 125. The number and arrangement of the openings 130 are determined so as not to affect the strength of the stay 125 and the like.

  As shown in FIG. 1, a sliding sheet 131, which is a fluorine-based lubricant holding member with good slidability, is wound around the nip forming member 124. Then, a sliding sheet 131 is screwed to a surface on the opposite side of the nip portion of the nip forming member 124 by a fixing member 133, which will be described later, to reduce the sliding load between the nip forming member 124 and the fixing belt inner peripheral surface. As a result, the friction between the nip forming member 124 and the inner peripheral surface of the fixing belt 21 increases the frictional resistance, thereby increasing the torque and preventing the slip phenomenon that the sheet is not fed at the linear speed at the nip portion N. ing.

  FIG. 4 is a diagram illustrating an example of a conventional fixing device 220. The basic configuration other than the configuration related to the stay 125 of the conventional fixing device 220 is substantially the same as the fixing device 20 of the present embodiment described with reference to FIG.

  In the conventional fixing device 220 shown in FIG. 4, the temperature of the entire fixing belt 21 is lower than a predetermined fixable temperature when the power is turned on or when printing is requested. Thereafter, the halogen heater 23 generates heat, and a portion of the fixing belt 21 (a portion surrounded by a dotted line in FIG. 4) on the upstream side in the fixing belt moving direction from the inlet of the nip portion N is warmed. When the nip portion N is reached with the rotation of, the fixing becomes possible. However, the slide 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 after a printing request. For this reason, 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 along.

  Further, since the fixing belt 21 does not have a driving source such as a motor, if the friction 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 that causes the friction load on the inner peripheral surface of the fixing belt 21 is greatly affected. Furthermore, the lubricating performance of the lubricant deteriorates over time due to evaporation of base oil components, oxidation, and mixing of foreign substances. In particular, in a high temperature environment, the degree of deterioration increases. For example, in the case of fluorine grease, the evaporation of the base oil component is more than doubled in a high temperature environment of 200 [° C.] or higher compared to a high temperature 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 slipping state even when a conventional driving force is received from the pressure roller, and the temperature of the heated portion of the fixing belt 21 rapidly increases. Due to thermal deformation, scars remain in 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 illustrating an example of the fixing device 20 of the present embodiment.
Therefore, in the present embodiment, as shown in FIG. 5, an opening 130 that penetrates in the direction from the halogen heater 23 toward the nip forming member 124 is provided in the stay 125 that supports the nip forming member 124. As a result, a portion (a portion surrounded by a broken line in FIG. 5) facing the opening 130 of the sliding sheet 131 wound around the nip forming member 124 is exposed to the halogen heater 23, and the sliding sheet 131 The exposed portion is directly heated by the halogen heater 23. As a result, the configuration in which the heat of the halogen heater 23 is transmitted to the nip portion by rotation of the fixing belt, the configuration in which the heat is transmitted by the fixing belt itself, or the configuration in which the heat is transmitted through the stay 125 and the nip forming member 124, The sliding sheet 131 can be heated after the printing request, and the viscosity of the lubricant can be lowered. Therefore, the fixing belt can be rotated after the power is turned on or after a print request. Further, the occurrence of paper jam and the thermal deformation of the fixing belt can be suppressed, and the occurrence of abnormal images can be suppressed.

  In addition, although demonstrated using the example which provided the opening part 130 in the stay 125 as shown in FIG. 5 as a structure which heats a sliding sheet | seat directly with a halogen heater, it does not restrict 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 nip portion side wound around the nip forming member 124. The structure which heats directly may be sufficient. 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 nip formation 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 paper conveyance direction (the cross-sectional area is the approximate center of the nip portion N in FIG. 1, and the horizontal direction in the drawing is the longitudinal direction (pressurization). In the drawing, the upper side 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 heat conduction member 242, a stay side high heat conduction member 243, and an internal high heat conduction member 244. As shown in an exploded view in FIG. 8, the base member 241 includes a central member 241C, two end members 241T, and two connecting members 241S. Examples of the base material 241 include polyether sulfone (PES), polyphenylene sulfide (PPS), liquid crystal polymer (LCP), polyether nitrile (PEN), polyamideimide (PAI), and polyether ether ketone (PEEK). It is possible to suitably use a heat resistant resin.

  The nip side high thermal conductivity member 242 is a high thermal conductivity member arranged so as to cover the nip side surface of the nip forming member 124, and a metal material having high thermal conductivity such as copper (Cu) or aluminum (Al) is suitable. Can be used. In the embodiment, copper (Cu) is used. The nip-side high thermal conductivity member 242 is a member arranged on the most nip side of the nip forming member 124, and directly (in more detail, in this example) heat from the fixing member (the fixing belt 21 in the embodiment). Although it is a member received via the sliding sheet 131, a nip side high thermal conductive member 242 which is a metal material having high thermal conductivity such as copper (Cu) or aluminum (Al) is provided in the paper width direction. . Accordingly, for example, when small-size paper is continuously passed, even if the fixing member temperature rises near the end of the paper passing area or in the non-paper passing area, the heat is transferred in the longitudinal direction (paper width direction) by the high heat conductive member. ) Can be efficiently moved and diffused, making it difficult for heat to accumulate on the surface. Therefore, it is possible to effectively suppress the so-called edge temperature rise during continuous paper feeding. At the same time, the presence of the low thermal conductivity portion in the vicinity of the end in the longitudinal direction limits heat escape to the end, and it is possible to suppress a decrease in the end temperature at the start of fixing. . As described above, in addition to the above-described conventional effects, in the configuration in which the opening is provided in the stay as the support member, the high heat conductive member is likely to be warmed, so that the temperature of the nip portion can be increased more quickly.

  In the nip side high thermal conductivity member 242 of this example, through holes 242a and 242a are formed in the vicinity of both end portions in the longitudinal direction, and the convex portion 241a provided on the end member 241T of the substrate 241 is a through hole. It is inserted into 242a. Thus, the entire surface (surface) on the nip side of the nip forming member 124 is configured to be a flat surface.

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

  The internal high heat conductive member 244 is a high heat conductive member disposed between the stay side high heat conductive member 243 and the base material 241 (in this example, the connection member 241S). Like the other high heat conductive members, copper (Cu) or aluminum is used. A metal material having high thermal conductivity such as (Al) can be suitably used. The position of the internal high heat conductive member 244 in the longitudinal direction (fixing belt rotation axis direction) is arranged so as to correspond to the end of the sheet when a small size paper (for example, A5 length) is passed, and the internal high heat conductive member 244 is arranged. Are arranged so that the end on the center side (the center side in the longitudinal direction) overlaps (overlaps) the end of the small size paper (for example, A5 length) paper passing area. Due to the internal high heat conductive member 244 arranged in this way, even when a small size paper is continuously passed, even if the temperature rises near the end of the paper passing area, the heat is efficiently transferred to the stay side high heat conductive member. 243 to diffuse and absorb heat in the longitudinal direction (paper width direction) and in the thickness direction of the nip forming member 124.

  In addition, in order to arrange the internal high heat conductive member 244, the thickness of the base material 241 (the vertical direction in the figure) is reduced at that portion, and in the illustrated example, the connection member 241S and the internal high heat conductive member 244 are stacked. Is set to be equal to the central member 241C of the base material.

  By the way, as for all the high heat conductive members, the larger the thickness (the thicker), the greater the effect of preventing the end temperature rise. However, when the thickness is too large, the warm-up is delayed and the energy efficiency is also lowered. Therefore, in the present embodiment, the thickness of the stay side high heat conductive member 243 is 2 [mm], the thickness of the internal high heat conductive member 244 is 1.5 [mm], and the thickness of the nip side high heat conductive member 242 is 0. 6 [mm]. In addition, the base member 241 has a thickness of the connecting member 241S of 1 [mm], and the central member 241C has a thickness of 2.5 [which is the 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 conductivity member 242 has an axial length (longitudinal direction = paper width direction = left-right direction in the drawing) of 344 [mm] and a width (8.5 mm from the end) ( A through hole 242a having an axial length of 7.0 [mm] is provided. The end on the center side of the through hole 242a, that is, the end on the center side of the convex portion 241a of the base material 241 is positioned outside (end side) from the outer end of the maximum size of the paper passing area that can pass paper. It is provided to do.

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

  7 and 8, the base material 241 is divided into a plurality of members and the internal high heat conduction member 244 is provided. However, the base material and each high heat conduction member are each divided. A plate-shaped member may be used, or an integral member having a convex portion or a concave portion may be used. In FIGS. 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 obtained by reducing the actual member as it is. Yes.

  In the configuration example shown in FIGS. 9 and 10, the base material 241 is formed of a single member and has a shape having a convex portion 241 a and a concave portion 241 b. In addition, the internal high heat conductive member 244 in FIG. 9 is omitted, and a single stay side high heat conductive member 243 having a convex portion 243a corresponding to this is used. The convex portion 243a has a shape that fits snugly into the concave portion 241b. The nip side high thermal conductive member 242 is the same as that shown in FIGS. The nip forming member 124 in which the respective members are combined has the same external shape as the nip forming member 124 of FIGS. The operation of each member is the same.

  In the fixing device of the present embodiment configured as described above, the nip forming member 124 has a first high thermal conductive layer (soaking layer) from the nip side (nip side soaking layer = first as shown in FIG. 9). 1 soaking layer), a base material layer, and a second high thermal conduction layer (soaking layer) (stay side soaking layer = second soaking layer).

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

  Here, since the convex part 241a of the base material is fitted to a part of the nip side high thermal conductive layer, the thermal conductivity in the longitudinal direction (axial direction) is not uniform, and the longitudinal direction (axial direction) ) In the vicinity of the end of the low thermal conductivity portion. With such a configuration, even when small-size paper is continuously passed during the fixing operation, even if the temperature rises near the edge 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 soaking layer, making it difficult for heat to accumulate on the surface. Therefore, it is possible to effectively suppress the so-called edge temperature rise during continuous paper feeding. At the same time, the presence of the low heat conduction part in the vicinity of the end in the longitudinal direction (axial direction) limits heat escape to the end (the end of the paper passing area), and the end of the fixing start-up It is possible to suppress the temperature drop of the part.

  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 an axial direction (longitudinal direction = paper width direction) length of 344 [mm] and a width of 8.5 [mm] from the end. A through hole 242a (FIG. 8) having an axial length of 7.0 [mm] is provided. The end on the center side of the through hole 242a, that is, the end on the center side of the convex portion 241a of the base material 241 is positioned outside (end side) from the outer end of the maximum size of the paper passing area that can pass paper. It is provided to do.

  In the present embodiment described above, the through-hole 242a is provided in the nip-side high thermal conductive member 242 which is the high thermal conductive layer that is the outermost layer (nip side) of the nip forming member 124, whereby the longitudinal direction (axial direction) of the high thermal conductive layer. ) Has a non-uniform (non-uniform) thermal conductivity. 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.

  In addition, as a relationship between the base material 241 and the nip side high heat conductive member 242, as shown in FIG. 11B, the nip portion may have a high heat conductive member. As shown in FIG. 12, by providing a high heat conductive member 245 on the opposite side of the nip portion of the nip forming member 124 that receives the heat of the halogen heater through the opening of the stay, the temperature of the nip portion is further increased. It can be raised quickly.

The high thermal conductive member 245 is made of a material having a higher thermal conductivity than the base material 241. For example, the high thermal conductivity member 245 includes carbon nanotubes (thermal conductivity: 3000 to 5500 [W / mK]), graphite sheet (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 conductive member 245 is preferably 236 [W / mK] or higher. On the other hand, the base material 241 is a resin material having high heat resistance, such as polyethersulfone (PES), polyphenylene sulfide (PPS), liquid crystal polymer (LCP), polyethernitrile (PEN), polyamideimide (PAI), polyether. It is formed with ether ketone (PEEK) or the like.
In addition, although the example comprised using the high heat transfer member for the nip formation member was demonstrated, it is not limited to this, You may comprise using a heat pipe instead of a high heat transfer member.

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

  As a heat transfer means for transferring radiant heat from the halogen heater to the sliding sheet in the nip portion, an opening is provided in the stay or the nip forming member as shown in FIG. Or a heat pipe. As a result, the radiant heat is transferred to the sliding sheet at the nip in the order of air and heat transfer means, so that the temperature of the lubricant held by the sliding sheet quickly rises even if the fixing belt does not rotate. It becomes viscous without slipping or thermal deformation. Also, it is effective to warm the entire lubricant by providing several openings and metal heat transfer means in the axial direction, and the opening cross-sectional shape of the opening may be round, square (FIG. 14) or the like. good. Moreover, as shown to Fig.14 (a), the opening part has two or more rows in an axial direction, and can ensure the intensity | strength of a stay, improving heat conduction. Moreover, as shown to FIG.14 (b), (c), when an opening part is arranged in zigzag form, a heating nonuniformity can be suppressed.

  Further, since the sliding sheet slides in a high-temperature environment near the halogen heater, fluorine grease or silicone oil having a high heat resistance temperature is appropriate as the lubricant retained by the sliding sheet. Fluorine grease is a lubricant in which a thickener is dispersed in a fluorine oil as a base oil and is in the form of a gel. Since the viscosity is higher than that of oil, it is effective as a countermeasure against spills from sliding parts. There is Knox lube. Since fluorine grease has a high viscosity, it has a feature that the viscosity torque increases. When speed fluctuation such as fixing belt slip is required with high accuracy, it is appropriate to use silicone oil with high heat resistance and low viscosity, similar to fluorine grease, such as KF-968-100CS made by Shin-Etsu Silicone. 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 fluorinated 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. 15, and the lower hole of the sliding sheet is wound on the upper protrusion of the nip forming member 124. Hook. Then, the sliding sheet 131 is screwed to the nip forming member 124 with screws 134 by the fixing member 133. In this way, by 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, over time, the frictional resistance increases due to the wear of the nip forming member 124 and the inner peripheral surface of the fixing belt, thereby increasing the torque and preventing the slip phenomenon that the sheet is not fed at the linear speed at the nip portion N. can do.

  In the sliding sheet, the area of the thread that appears on the front surface is different from that on the back surface depending on how the sheet-like fibers are woven. The plain weave has the same area ratio on the surface of the warp and weft, but the twill or satin weave has more surface area on the surface than the weft. When knitting two or more types of fibers, increase the area of the fluororesin in the part that becomes the friction surface, and increase the area of the resin that has high strength or high oil content in the part that becomes the back surface. Friction and wear characteristics are good and the sheet is strong. 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 transmitted to the sliding sheet 131 in the nip portion. Therefore, the viscosity of the lubricant held by the sliding sheet can be lowered almost simultaneously with the rotation of the fixing belt, and the occurrence of abnormal images and paper jams due to slip as in the prior art can be suppressed.

  Further, the base member of the fixing belt may not have good slidability with the material, and it is appropriate to apply a ceramic or fluorine coating to reduce the frictional load on the surface. Fluorine-based PTFE and PFA coatings are often used as slidable fluorine coatings because of their low reactivity with other materials and high heat resistance. There are PFA and PTFE grades depending on the temperature and application. Ceramic-based coatings are harder and harder to wear than fluorine coatings, and are effective when it is desired to avoid an increase in the viscosity of the lubricant due to coating abrasion. In addition, fluorine-based coatings have better adhesion to metals than resins. For example, if the heat resistance of the resin is insufficient or if you want to increase the heat transfer in the axial direction, you can coat the metal such as SUS. Is optimal. Further, as shown in FIG. 17, the peripheral structure of the nip forming member that has been conventionally made of resin is not required to have screws, screwing parts, and the like, and the number of parts can be greatly reduced and the cost can be reduced.

What has been described above is merely an example, and the present invention has a specific effect for each of the following modes.
(Aspect A)
A rotatable endless fixing member such as the fixing belt 21, a pressure rotating body such as a pressure roller 22 that presses in contact with the outer peripheral surface of the fixing member, and an inner peripheral surface side of the fixing member. A nip forming member 124 that forms a nip portion with the pressure rotator 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 the 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 thereby form an image. In the fixing device 20 for fixing the toner to the recording material, heat transfer means such as an opening 130 for transmitting 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. It is what.
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 transmitted to the lubricant holding member. If the heated portion of the heated fixing member does not reach 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, immediately after the heating element is driven, the heat of the heating element is retained in the nip portion by the heat transfer means without rotating the fixing member. It is transmitted to the member. This makes it possible to reduce the viscosity of the lubricant held by the lubricant holding member after the power is turned on or after a print request so that the fixing member can be rotated. Therefore, the fixing member can be rotated after the power is turned on or after a print request.

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

(Aspect C)
In (Aspect B), the nip forming member is provided with an opening 132 connected to the opening provided in the support, and 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, after the power is turned on or after printing is requested, the heat of the heating element is transmitted to the sheet-like lubricant holding member wound around the nip forming member through the opening of the support and the opening of the nip forming member. The lubricant held by the lubricant holding member rises to a temperature at which the fixing member can be rotated. Therefore, the fixing member can be rotated after power is turned on or after a print request.

(Aspect D)
In (Aspect A) to (Aspect C), the nip forming member is provided on the base member 241 and the fixing member side, and has a high thermal conductivity as the nip side high thermal conductive member 242 having a higher thermal conductivity than the base member. It is comprised from a member, It is characterized by the above-mentioned.
According to this aspect, since the nip forming member has the high heat conductive member, the nip portion is easily warmed up. Therefore, the warm-up time and first print time can be shortened.

(Aspect E)
In (Aspect B), the openings of the support are formed in a plurality of rows in the direction of the pressing rotary body rotation axis of the support.
According to this aspect, the number of openings in the support is relatively large while ensuring the strength of the support, and thus 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 infiltrated, and the outflow of the lubricant can be suppressed.

(Aspect G)
An image carrier such as a 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 71 or the like and a fixing unit such as a fixing device 20 for fixing the toner image transferred onto the recording medium to the recording medium, the fixing unit (Aspect A) The fixing device according to any one of (Aspect F) is used.
According to this aspect, the lubricant retained by the lubricant retaining member can be heated after the power is turned on or after printing is requested, and the lubricating performance by the lubricant can be enhanced. Accordingly, it is possible to suppress the rotation failure of the fixing member that has occurred without the viscosity of the lubricant being lowered, and it is possible to perform good image formation.

DESCRIPTION OF SYMBOLS 1 Image forming apparatus 3 Feed roller 4 Registration roller pair 5 Secondary transfer roller 7 Paper discharge 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 discharge tray DESCRIPTION OF SYMBOLS 20 Fixing device 21 Fixing belt 22 Pressure roller 22a Metal core 22b Elastic layer 22c Release layer 23 Halogen heater 24 Nip forming member 25 Reflecting member 26 Separating plate 30 Charging device 40 Developing device 50 Cleaning device 61 Paper feeding device 71 Transfer device 72 Driving Roller 73 Followed Roller 100 Fixing Belt 120 Photosensitive Drum 124 Nip Forming Member 125 Stay 130 Opening Portion 131 Sliding Sheet 132 Opening Portion 133 Fixing Member 134 Screw 200 Metal Heat Conductor 220 Fixing Device 241 Base Material 242 -Up-side high thermal conductivity member 243 stays side high thermal conductivity member 244 inside the high thermal conduction member 245 high thermal conductivity member 300 heat source 400 pressure roller

JP 2013-152397 A

Claims (7)

A rotatable endless fixing member, a pressure rotating body that contacts and pressurizes the outer peripheral surface of the fixing member, and the pressure rotation through the fixing member disposed on the inner peripheral surface side of 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 in the nip A fixing device that is interposed between a member and an inner peripheral surface of the fixing member, and passes the recording material through the nip portion to fix the image on the recording material.
A fixing device comprising heat transfer means for transmitting heat of the heating element to the lubricant holding member in a state where the fixing member is stopped. The fixing device according to claim 1.
A support for supporting the nip forming member;
As the heat transfer means, the support is provided with an opening that communicates a space where the heating element exists and a space where the sheet-like lubricant holding member wound around the nip forming member exists. A fixing device. The fixing device according to claim 2.
The nip forming member is provided with an opening so as to be connected to the opening provided in the support, and the lubricating element is lubricated by the heating element through the opening of the support and the opening of the nip forming member. A fixing device that heats an agent holding member. The fixing device according to any one of claims 1 to 3,
The fixing device according to claim 1, wherein the nip forming member includes a base material and a high heat conductive member provided on the fixing member side and having a higher thermal conductivity than the base material. The fixing device according to claim 2.
The fixing device according to claim 1, wherein the openings of the support are formed in a plurality of rows in a direction of a rotation axis of the pressure rotator of the support. The fixing device according to any one of claims 1 to 5,
The fixing device according to claim 1, wherein the lubricant holding member is made of a fluorine-based fiber. An image carrier, a toner image forming unit that forms a toner image on the image carrier, a transfer unit that transfers the toner image from the image carrier onto a recording medium, and a toner that is transferred onto the recording medium In an image forming apparatus comprising fixing means for fixing an image on the recording medium,
An image forming apparatus using the fixing device according to claim 1 as the fixing unit.

Images