JP2017111332A - Fixing device and image forming apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a fixing device that can suppress a lubricant from leaking from the ends of a fixing belt to the outside, and an image forming apparatus using the fixing device.SOLUTION: Regulation members 28 regulating a movement of a lubricant adhered to a fixing belt 21 to both ends of the fixing belt 21 are provided on the inside of the ends of the fixing belt 21. The regulation members 28 are formed of fluororubber, provided on a nip forming member 24 to be in contact with an inner peripheral surface of the fixing belt 21, and has a lower lubricant absorbency than that of a lubricant impregnated member, such as a slide member 24a impregnated with lubricant.SELECTED DRAWING: Figure 11

Description

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

  2. Description of the Related Art Conventionally, as a fixing device with a short warm-up time and low power consumption, an image forming apparatus having a fixing device that forms a nip portion by pressing a nip forming member against a pressure member with a fixing belt interposed therebetween is known. It has been.

  Patent Document 1 discloses a fixing device of this type, in which a sliding sheet, which is a lubricant-impregnated member that impregnates a lubricant such as silicone oil, is attached to a contact portion of the nip forming member with a fixing belt. Is described.

  The lubricant impregnated in the sliding sheet adhered to the nip forming member adheres to the inner peripheral surface of the fixing belt, and the lubricant is interposed between the sliding sheet and the fixing belt. Accordingly, it is described that the frictional force between the sliding sheet and the fixing belt can be reduced by the lubricating effect of the lubricant, and the fixing belt can be smoothly rotated.

  The lubricant adhering to the inner peripheral surface of the fixing belt from the sliding sheet makes a round as the fixing belt moves, and is dammed to the upstream end of the nip forming member in the rotation direction of the fixing belt. It is described that the dammed lubricant moves in the belt width direction, and a part of the lubricant leaks out from the end of the fixing belt.

  In order to prevent such a problem, Patent Document 1 discloses that the lubricant adhering to the fixing belt is collected upstream of the nip forming member in the rotation direction of the fixing belt, and the collected lubricant is collected in the belt width direction. A lubricant circulation member that is reattached to the fixing belt is provided so as to approach the center.

  Specifically, the lubricant circulating member has a lubricant retaining property and has a plurality of grooves. These grooves are inclined so that the downstream side in the rotation direction of the fixing belt is positioned at the center in the width direction of the fixing belt, rather than the upstream side. The lubricant of the lubricant circulating member that oozes out into the groove and adheres to the surface of the fixing belt moves to the center in the belt width direction while being guided by the groove. As a result, the lubricant adhering to the inner peripheral surface of the belt is drawn toward the center in the belt width direction.

  Thus, it is described that the lubricant can be prevented from leaking from the end portion in the width direction of the fixing belt by bringing the lubricant to the center in the belt width direction by the lubricant circulating member.

  However, the lubricant circulating member has a function of absorbing and holding the lubricant adhering to the fixing belt, and the lubricant absorbed by the lubricant circulating member is the longitudinal direction of the lubricant circulating member (fixing belt). The leaked lubricant may move to the end of the fixing belt and leak from the end of the fixing belt to the outside.

  In order to solve the above-described problems, the present invention provides a rotatable endless fixing belt, a pressure member in contact with the outer peripheral surface of the fixing belt, and the fixing belt disposed on the inner peripheral side of the fixing belt. A nip forming member that abuts on the pressure member to form a nip portion, and a lubricant impregnated member that is provided on the nip forming member so as to contact the inner peripheral surface of the fixing belt and impregnates the lubricant. In the fixing device, the lubricant is absorbed more than the lubricant-impregnated member, which restricts the movement of the lubricant adhering to the fixing belt to the end of the fixing belt inside the both ends of the fixing belt. This is characterized in that a regulating member having low properties is provided.

  According to the present invention, the lubricant can be prevented from leaking from the end portion of the fixing belt to the outside.

1 is a schematic configuration diagram of an image forming apparatus according to an embodiment. FIG. 3 is a diagram illustrating an example of a conventional fixing device that indirectly heats a fixing belt via a metal heat conductor. 1 is a schematic configuration diagram illustrating an example of a fixing device according to an embodiment. (A) is a perspective view of a flange member, (b) is a front view of a flange member. The top view of a shielding member. The figure which shows the heat-emitting part of each halogen heater. FIG. 3 is a perspective view of a fixing device when passing a small-size sheet. FIG. 6 is a cross-sectional view of the fixing device when passing a small-size sheet. FIG. 3 is a perspective view of a fixing device when passing a large-size sheet. FIG. 3 is a cross-sectional view of a fixing device when passing a large size sheet. The schematic diagram which looked at the nip forming member periphery from the pressure roller side. The expanded sectional view of the part enclosed with the broken line D of FIG. FIG. 9 is a schematic view of the periphery of a nip forming member in a fixing device according to a modification as viewed from the pressure roller side. The expanded sectional view of the part enclosed with the broken line D of 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. 1 is a schematic configuration diagram of an image forming apparatus 100 according to the present embodiment.
An image forming apparatus 100 illustrated in FIG. 1 is a tandem color laser printer, and includes an image forming unit (four image forming units in the illustrated example) 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. 1, an image forming apparatus 100 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.

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

  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 112Bk 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 photosensitive drum 120Bk after charging, the optical writing device 6 as an exposure unit that exposes the surface of the photosensitive drum 120Bk is used.

  The optical writing device 6 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 6 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, when the intermediate transfer belt 11 moves in the direction A1 in the figure, visible images (toner images) formed on the photosensitive drums 120Y, 120C, 120M, and 120Bk are transferred to the intermediate transfer belt 11. It is performed so that it is transferred to the same position.

  More specifically, a primary transfer bias is applied to each of a plurality of primary transfer rollers 112Y, 112C, 112M, and 112Bk 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 112Y, 112C, 112M, and 112Bk 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 112Y, 112C, 112M, and 112Bk sandwich the intermediate transfer belt 11 with the corresponding photosensitive drums 120Y, 120C, 120M, and 120Bk to form a primary transfer nip. A power source is connected to each primary transfer roller 112Y, 112C, 112M, 112Bk. A primary transfer bias composed of at least one of a predetermined direct current voltage (DC) and alternating current voltage (AC) is applied to each primary transfer roller 112Y, 112C, 112M, 112Bk by this power source.

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

  In addition to the plurality of image forming units, the image forming apparatus 100 includes a transfer belt unit 10, a secondary transfer roller 5, a transfer belt cleaning device 113, and an optical writing device 6.

  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 112Y, 112C, 112M, and 112Bk, 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 the drawing.

  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 113 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 112 </ b> Y, 112 </ b> C, 112 </ b> M, and 112 </ b> Bk, the secondary transfer roller 5, and the transfer belt cleaning device 113.

  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 112Y, 112C, 112M, and 112Bk, the secondary transfer roller 5 is also connected to a power source, and is composed of at least one of a predetermined DC voltage (DC) and an AC voltage (AC). A secondary transfer bias is applied to the secondary transfer roller 5.

  The transfer belt cleaning device 113 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 illustrated example, the transfer belt cleaning device 113 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 113 is connected to the inlet of the waste toner container.

  Further, the image forming apparatus 100 includes a sheet feeding device 61 on 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 provided at the lower part of the main body of the image forming apparatus 100 and has a feeding roller 3 as a recording material feeding unit that comes into contact with the upper surface of the uppermost sheet P. Then, the uppermost sheet P is fed toward the registration roller pair 4 by the feeding roller 3 being driven to rotate counterclockwise in the drawing.

  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 100 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 pair 7 as a recording material discharging unit, and a recording material stacking unit. As a paper discharge tray 17. The paper discharge roller pair 7 discharges the fixed paper P to the outside of the main body of the image forming apparatus 100. The paper discharge tray 17 is disposed on the upper part of the main body of the image forming apparatus 100 and stacks and stores the paper P discharged to the outside of the main body of the image forming apparatus 100 by the pair of paper discharge rollers 7.

  Further, the image forming apparatus 100 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. 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 113 provided in the transfer device 71 includes 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 113 has a discharge 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 100 will be described.
When the image forming operation is started in the image forming apparatus 100, the photosensitive drums 120Y, 120C, 120M, and 120Bk in the respective image forming units are rotationally driven in the clockwise direction in the drawing by the driving device. The surfaces of the photosensitive drums 120Y, 120C, 120M, and 120Bk are uniformly charged to 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 6, 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 photoconductive 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, so that the electrostatic latent images become toners. The image is visualized (visualized).

  When the image forming operation is started, the driving roller 72 is driven to rotate counterclockwise in FIG. 1, and the intermediate transfer belt 11 is rotated in the direction of arrow A1 in the drawing. Then, a constant voltage or a constant current-controlled voltage having a polarity opposite to the charging polarity of the toner is applied to each primary transfer roller 112Y, 112C, 112M, 112Bk. As a result, a predetermined transfer electric field is formed in the primary transfer nip between each primary transfer roller 112Y, 112C, 112M, 112Bk and each photosensitive drum 120Y, 120C, 120M, 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 100, 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 113, 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 pair 7 and stocked on the paper discharge tray 17.

  The above description is an image forming operation when a full-color image is formed on the paper P. A single-color image is formed using any one of the four image forming units, or two or three. It is also possible to form a two-color or three-color image using two image forming units.

  Further, the image forming apparatus shown in FIG. 1 is a color printer using a tandem system in which image forming units for forming a plurality of color images are juxtaposed along the belt extending direction. However, the present invention is not limited to this system. It is also possible to target not only printers but also copying machines and facsimiles.

  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 material such as paper and 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 that are in contact with 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 method, 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 (for example, Patent Document 2).

  In the film fixing method, 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 (for example, Patent Document 3).

  In the electromagnetic induction heating and fixing method, a configuration in which an electromagnetic induction coil that enhances heat generation efficiency is provided on a heating member is used (for example, Patent Document 2).

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 moving at high speed must be increased. This is because the amount of heat necessary for fixing is given to the sheet as the time for the sheet 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 can be reduced 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 deal with such problems, a fixing device has been proposed in which a fixing belt can be used to obtain a good fixing property even if it is mounted on a high-production image forming apparatus. For example, Patent Document 4).

  In the fixing device disclosed in Patent Document 4, the configuration shown in FIG. 2 is used. The fixing belt 21, the pipe-shaped metal heat conductor 200 disposed in the fixing belt 21, the heat source 300 disposed in the metal heat conductor 200, and the metal heat conductor 200 via the fixing belt 21. Is provided with a pressure roller 400 that forms a fixing nip N.

  The fixing belt 21 is rotated by the rotation of the pressure roller 400. At this time, the metal heat conductor 200 guides the movement of the fixing belt 21. Further, the fixing belt 21 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 21 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.

  Therefore, a configuration in which the fixing belt is directly heated rather than indirectly heated via a metal heat conductor (a member denoted by reference numeral 200 in FIG. 2) is employed. As a result, power consumption can be reduced, and the first print time from the heating standby time can be further shortened. Moreover, the cost reduction by not providing a metal heat conductor can also be anticipated.

FIG. 3 is a schematic configuration diagram illustrating an example of the fixing device 20 according to the present embodiment.
The fixing device 20 includes a fixing belt 21 as a fixing member that is a surface endless moving body having a hollow inside, and a pressure roller 22 as a pressure member that is rotatably provided facing the fixing belt 21. Yes.

  Inside the fixing belt 21, a heating device 23 as a heat source for heating the fixing belt 21, a pressure roller 22 opposed via the fixing belt 21, and a nip forming member 24 that forms a fixing nip portion N are provided. ing. Further, on the inner side of the fixing belt 21, a reflection that reflects light emitted from the stay 25 as a supporting member that supports the nip forming member 24 and the two halogen heaters 23 </ b> A and 23 </ b> B included in the heating device 23 to the fixing belt 21. A member 26 is provided.

  Further, guide portions 451a of flange members 451 (see FIG. 4) as guide members are inserted into both ends in the width direction of the fixing belt 21, and the fixing belt 21 is rotatable while being guided by the guide portions 451a. Is retained. A light shielding member 29 is provided inside the fixing belt 21, and the light shielding member 29 is not in contact with the fixing belt 21 along the inner peripheral surface of the fixing belt 21 as indicated by an arrow A in the figure. Is configured to move.

The fixing belt 21 is a thin and flexible endless belt member (including a film).
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.

  Further, an elastic layer formed of a rubber material such as silicone rubber, foamable silicone rubber, or fluorine rubber may be interposed between the base material and the release layer. When there is no elastic layer, the heat capacity is reduced and the fixability is improved. This causes a defect that remains. In order to improve this, it is preferable to provide an elastic layer of 100 μm or more such as silicone rubber. Due to the deformation of the elastic layer, subtle unevenness is absorbed and the skin image is improved.

  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 in contact with the nip forming member 24 through the fixing belt 21 by being pressed toward the fixing belt 21 by a pressing means such as a spring. At the location 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 fixing nip portion N having a predetermined width.

  The pressure roller 22 is rotationally driven by a driving force transmitted from a driving source such as a motor provided in the printer main body via a gear. When the pressure roller 22 is rotationally driven, the driving force is transmitted to the fixing belt 21 at the fixing nip portion N, and the fixing belt 21 is driven to rotate.

  In the present embodiment, the pressure roller 22 is a solid roller, but may be a hollow roller. In that case, a heating source such as a halogen heater may be disposed inside the pressure roller 22. Further, when there is no elastic layer, the heat capacity is reduced and the fixability is improved. The elastic layer 22b may be solid rubber, but if 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.

  The heating device 23 includes a first halogen heater 23 </ b> A and a second halogen heater 23 </ b> B as heat sources, and both ends are fixed to the side plate of the fixing device 20. The halogen heaters 23A and 23B generate heat by being output controlled by a power supply unit disposed in the printer body. The output control is performed based on the detection result of the surface temperature of the fixing belt 21 by the temperature detection sensor.

  By such output control of the halogen heaters 23A and 23B, the temperature of the fixing belt 21 (fixing temperature) can be maintained at a desired temperature. In addition to the halogen heater, an IH (electromagnetic induction), a resistance heating element, a carbon heater, or the like may be used as a heating source for heating the fixing belt 21.

  The nip forming member 24 is a member that determines the shape of the fixing nip portion N in response to the pressure applied by the pressure roller 22. For this reason, it is arranged in parallel with the axial direction of the fixing belt 21 or the axial direction of the pressure roller 22 and is fixedly supported by a stay 25 used as a support member of the nip forming member 24.

  In this way, by supporting the nip forming member 24 with the stay 25, it is possible to suppress the nip forming member 24 from being bent by the pressure of the pressure roller 22, and to be uniform in parallel with the axial direction of the pressure roller 22. A nip width is obtained.

  The stay 25 is preferably formed of a metal material having high mechanical strength such as stainless steel or iron in order to satisfy the bending prevention function of the nip forming member 24. However, the stay 25 may be made of resin. Is possible.

  In this embodiment, the fixing nip portion N has a flat shape, but may have a concave shape or other shapes. When the fixing nip portion N has a concave shape, the discharge direction of the leading edge of the paper P is closer to the pressure roller 22 and the separation is improved, so that the occurrence of jam is suppressed.

  Further, a sliding member 24 a which is a lubricant-impregnated member impregnated with a lubricant is attached to the surface of the nip forming member 24. The sliding member 24a is a sheet in which fine fluorine-based fibers having heat resistance are woven, and the lubricant is absorbed by a capillary phenomenon.

  Examples of the lubricant include silicone oil, which are desirable in terms of heat resistance, durability and lubricating ability, and can be selected from those having various viscosities depending on use conditions. Other lubricants include fluorine-based and silicon-based grease.

  The reflecting member 26 is disposed between the stay 25 and the heating device 23 using aluminum, stainless steel, or the like whose surface can be used as a reflecting surface. Here, since the reflecting member 26 is directly heated by the heating device 23, it is desirable that the reflecting member 26 be formed of a high melting point metal material or the like.

  Since the reflecting member 26 is disposed between the stay 25 and the heating device 23, the light emitted from the halogen heaters 23 </ b> A and 23 </ b> B of the heating device toward the stay 25 is reflected to the fixing belt 21. As a result, the amount of light applied to the fixing belt 21 can be increased, and the fixing belt 21 can be efficiently heated.

  Further, since it is possible to suppress the radiant heat from the halogen heaters 23A and 23B from being transmitted to the stay 25 and the like, energy saving can be achieved. Further, without providing the reflecting member 26 as in the present embodiment, the reflecting surface may be formed by subjecting the surface of the stay 25 on the heating device 23 side to a mirror surface treatment such as polishing or painting.

  However, the shape and material of the stay 25 cannot be freely selected in order to ensure its strength. For this reason, if the reflecting member 26 is separately provided as in the present embodiment, the degree of freedom in selecting the shape and material is increased, and the reflecting member 26 and the stay 25 can be specialized in their functions.

  Further, since the reflecting member 26 is provided between the heating device 23 and the stay 25, the position of the reflecting member 26 with respect to the heating device 23 becomes close, so that the fixing belt 21 can be efficiently heated.

  It moves between the fixing belt 21 and the heating device 23 between a shield position that shields radiant heat from the halogen heaters 23A and 23B to the non-sheet passing area of the fixing belt 21 and a retracted position that is retracted from the shield position. A possible shielding member 29 is provided. Thereby, in particular, an excessive temperature rise in the non-sheet passing region of the fixing belt 21 during continuous sheet feeding can be suppressed, and deterioration or damage of the fixing belt 21 due to heat can be prevented.

  The moving operation of the shielding member 29 between the shielding position and the retracted position is performed by a driving force from a driving source included in a driving device that is a driving unit controlled by the control unit.

  The shielding member 29 is configured by forming a metal plate having a thickness of 0.1 [mm] to 1.0 [mm] into an arcuate cross-sectional shape along the inner peripheral surface of the fixing belt 21. Further, the shielding member 29 is movable in the circumferential direction of the fixing belt 21.

FIG. 4A is a perspective view of the flange member 451, and FIG. 4B is a front view of the flange member 451.
The flange members 451 disposed at both ends in the width direction of the fixing belt 21 have the same shape. As shown in FIG. 4, the flange member 451 includes an attachment portion 451 b attached to the side plate of the fixing device 20 and a guide portion 451 a facing one end of the inner peripheral surface of the fixing belt 21.

  The guide portion 451a has a substantially cylindrical shape with the pressure roller side cut out. The guide portion 451a has an outer diameter substantially equal to the inner diameter of the fixing belt 21, and has a length that enters a predetermined amount from both ends of the fixing belt 21 to the inside. In other words, the guide portion 451a is a circumferential guide convex portion, and is inserted into the end portion of the fixing belt 21 and slides to maintain the cross-sectional shape of the fixing belt 21 in a circular shape.

  A through hole 451c is provided at a position corresponding to the inside of the guide portion 451a of the attachment portion 451b, and the stay 25 and the heating device 23 are attached to the side plate of the fixing device 20 through the through hole 451c.

  The fixing device 20 according to the present embodiment has various contrivances in the configuration in order to further improve energy saving and first print time.

  Specifically, the fixing belt 21 can be directly heated at a place other than the fixing nip portion N by the heating device 23 (direct heating method). Further, in order to reduce the heat capacity of the fixing belt 21, the fixing belt 21 is thin and has a small diameter.

  In this embodiment, the only members that contact the inner peripheral surface of the fixing belt 21 are the guide portion 451a of the flange member 451 and the nip forming member 24. In addition to these members, the members contact the inner peripheral surface of the fixing belt 21. There is no belt guide that guides rotation.

  The basic operation of the fixing device 20 according to the present embodiment will be described below with reference to FIG.

  When the power switch of the printer main body is turned on, electric power is supplied to the halogen heater 23, and the pressure roller 22 starts to rotate clockwise in FIG. As a result, the fixing belt 21 is driven to rotate counterclockwise in FIG. 3 by the frictional force with the pressure roller 22.

  Thereafter, the paper P carrying the unfixed toner image T in the above-described image forming process is fed into the fixing nip N of the fixing belt 21 and the pressure roller 22 that are in a pressure contact state. Then, the toner image T is fixed on the surface of the paper P by heat from the fixing belt 21 heated by the heating device 23 and pressure applied between the fixing belt 21 and the pressure roller 22.

  The paper P on which the toner image T is fixed is carried out from the fixing nip portion N, and the carried-out paper P is discharged out of the apparatus by the paper discharge roller pair 7 (see FIG. 1) as described above and discharged. Stocked on tray 17 (see FIG. 1).

  Next, the shielding member 29 disposed between the fixing belt 21 and the heating device 23 will be specifically described.

  FIG. 5 shows a plan view of the shielding member 29. As shown in FIG. 5, the shielding member 29 has a shielding portion 48 formed in a shape having three step portions at both ends. That is, each shielding part 48 is comprised by the 1st shielding area part 48a, the 2nd shielding area part 48b, and the 3rd shielding area part 48c. Further, the third shielding region portions 48 c of the shielding portions 48 are connected to each other through a connecting portion 49.

  In the present embodiment, the width W1 between the third shielding region portions 48c corresponds to the small size sheet passing width, the width W2 between the second shielding region portions 48b corresponds to the medium size sheet passing width, A width W3 between the one shielding region portions 48a corresponds to a large size sheet passing width. In the present embodiment, the small size sheet passing width corresponds to the width of “postcard”, and the medium size sheet passing width corresponds to the width of “B4 size”. The large-size sheet passing width corresponds to the width of “A3 size”. An example of the paper size corresponding to the paper passing width is not limited to this.

FIG. 6 is a view showing a heat generating portion of each of the halogen heaters 23A and 23B.
In the present embodiment, the lengths and arrangement positions of the heat generating portions of the halogen heaters 23A and 23B are varied. That is, as shown in FIG. 6, the heat generating portion 231a of the first halogen heater 23A is disposed on the central portion in the longitudinal direction, and the heat generating portion 231b of the second halogen heater 23B is disposed on both ends in the longitudinal direction. Has been. The heat generating portion of the first halogen heater 23A corresponds to a range that is not less than the small size sheet passing width W1 and less than the medium size sheet passing width W2. In addition, the heat generating portion of the second halogen heater 23B is disposed in a range that is equal to or larger than the sheet passing width W2 of the medium size sheet and includes the large size sheet passing width W3.

  FIG. 7 is a perspective view of the fixing device 20 when a small-size sheet is passed. FIG. 8 is a cross-sectional view of the fixing device 20 when a small-size sheet is passed.

  The width W1 between the third shielding region portions 48c corresponding to the small size paper whose width is equal to or smaller than the width of “postcard” is smaller than the length of the heat generating portion of the first halogen heater 23A. Therefore, when small-size paper is passed, only the first halogen heater 23A generates heat. However, in this case, since the range of the fixing belt 21 heated by the first halogen heater 23A exceeds the small size sheet passing width W1, the shielding member 29 is moved to the shielding position corresponding to the small size sheet passing width.

  That is, as shown in FIG. 8, the shielding member is moved to the shielding position corresponding to the small-sized paper located up to the third shielding area 48 c in the direct heating area M of the heating device 23. As a result, the outer range from the vicinity of the end of the small size sheet passing width W1 can be shielded by the first, second, and third shielding region portions. Therefore, at least when the non-sheet passing area of the fixing belt 21 passes through the portion shielded by the first, second and third shielding area portions, it is not directly heated by the halogen heater. As a result, the temperature rise of the fixing belt 21 can be suppressed in the non-sheet passing region as compared with the case where the shielding member 29 does not shield the sheet.

  Next, when passing the medium size paper exceeding the width of “postcard” and not more than the width of “B4 size”, both the first halogen heater 23A and the second halogen heater 23B generate heat. . In this case, if the first halogen heater 23A and the second halogen heater 23B generate heat, the heated range of the fixing belt 21 exceeds the medium size sheet passing width W2.

  Therefore, when passing the medium size sheet, the shielding member 29 is moved to the shielding position corresponding to the medium size sheet passing width. That is, the third shielding area 48 c is retracted directly from the heating area M, and the first shielding area 48 a and the second shielding area 48 b are positioned in the heating area M. As a result, the outer range from the vicinity of the end of the medium-size sheet passing width W2 can be shielded by the first shielding region portion 48a and the second shielding region portion 48b. Thereby, at least when the non-sheet passing area of the fixing belt 21 passes through the portion shielded by the second shielding area 48b and the first shielding area 48a, it is not directly heated by the halogen heater. Accordingly, it is possible to suppress an increase in the temperature of the fixing belt 21 in the non-sheet-passing region as compared with the case where the shielding member 29 does not shield it.

  FIG. 9 is a perspective view of the fixing device 20 when a large-size sheet is passed. FIG. 10 is a cross-sectional view of the fixing device 20 when a large-size sheet is passed.

  When passing a large size sheet exceeding the width of “B4 size”, both the halogen heater 23A and the halogen heater 23B generate heat. In this case, if the halogen heater 23A and the halogen heater 23B generate heat, the heated range of the fixing belt 21 exceeds the sheet passing width W3 of the large size paper.

  Therefore, when passing large-size paper, the shielding member 29 is moved to the shielding position for large-size paper. That is, as shown in FIG. 10, the second shielding region portion 48 b and the third shielding region portion 48 c are retracted directly from the heating region M, and only the first shielding region portion 48 a is moved so as to be positioned in the direct heating region M. Let

  Thereby, at least when the non-sheet passing region of the fixing belt 21 passes through the portion shielded by the first shielding region portion 48a, it is not directly heated by the halogen heater. As a result, the temperature rise of the fixing belt 21 can be suppressed in the non-sheet passing region as compared with the case where the shielding member 29 does not shield the sheet.

  Further, the third shielding area 48c is also retracted directly from the heating area M when passing the maximum size sheet that the printer can pass, such as A3 Nobi.

  7, 8, 9, and 10, illustration of the pressure roller 22 and the like is omitted as appropriate.

  As described above, by providing the shielding member 29, even when a sheet having a width smaller than that of the halogen heaters 23A and 23B is continuously passed in the fixing belt width direction, the non-sheet passing region of the fixing belt 21 is overheated. It can be suppressed. Thus, it is not necessary to perform control such as reducing productivity in order to cancel the excessive temperature rise region.

Next, features of the present embodiment will be described.
FIG. 11 is a schematic view of the periphery of the nip forming member 24 as viewed from the pressure roller side.
Note that an arrow C in the drawing indicates the surface movement direction of the fixing belt 21.
As shown in FIG. 11, the longitudinal direction (fixing belt width direction) length L1 of the sliding member 24a is shorter than the length between the guide portions 451a of the flange member 451, and the nip formation with the end portion of the guide portion 451a. Between the longitudinal ends of the member 24, there is a predetermined gap L5. In the present embodiment, the width L4 of the fixing belt 21 is 360 mm, the longitudinal direction of the sliding member 24a (the width direction of the fixing belt) L1: 344 mm, the end of the guide portion 451a, and the longitudinal end of the nip forming member 24. Part and gap L5: 5 mm.

  A sliding member 24 a that is a lubricant-impregnated member impregnated with a lubricant 201 such as silicone oil is attached to the surface of the nip forming member 24. When the sliding member 24 a is pressed by the pressure roller 22 through the fixing belt 21, the lubricant 201 impregnated in the sliding member 24 a is squeezed out and adheres to the inner peripheral surface of the fixing belt 21. To do. The lubricant 201 adhering to the inner peripheral surface of the fixing belt 21 circulates while adhering to the fixing belt 21 and is dammed to the upstream end of the nip forming member 24 in the fixing belt rotation direction, and then the arrow in the figure. B is absorbed by the sliding member 24a.

  However, the lubricant may move toward the end of the fixing belt 21 when the nip forming member 24 is blocked by the upstream end of the fixing belt rotating direction. When the lubricant moves to the outside of the end in the longitudinal direction of the sliding member 24a, the lubricant 201 is not absorbed by the sliding member 24a. As a result, the lubricant contained in the sliding member 24a gradually decreases, the lubricating effect of the lubricant 201 is lost, and the torque of the fixing device increases.

  In addition, the lubricant 201 that has moved to the outside of the end portion in the longitudinal direction of the sliding member 24a is not dammed by the nip forming member 24, and recirculates together with the fixing belt. Then, the lubricant 201 moved to the outside of the longitudinal end portion of the sliding member 24a moves toward the end portion of the fixing belt 21, and adheres to the guide portion 451a of the flange member 451, and finally. There was a risk of leakage from the end of the fixing belt.

  Therefore, in the present embodiment, a regulating member 28 that regulates the movement of the lubricant 201 toward the fixing belt end is provided. The regulating members 28 are provided at both ends in the longitudinal direction of the upstream end surface of the nip forming member 24 in the rotation direction of the fixing belt 21. The regulating member 28 is made of a heat-resistant elastic material such as fluororubber, and is made of a material having a lower absorbability of the lubricant 201 than the sliding member 24a.

“Absorptivity” refers to the ease of absorption of a lubricant in a liquid state, and “absorbability” of a material is, for example, as described in “JIS L 1907 water absorption test method for textile products”. Moreover, it can evaluate using test methods, such as a dripping method, a birec method, and a sedimentation method. For example, the evaluation of “absorbability” using the birec method is performed as follows. That is, a test piece having a size of 200 mm in the vertical direction and 25 mm in the horizontal direction is prepared using the absorber (sample), and the upper end of the test piece is fixed so as to be vertical. Next, the lower end is immersed in a liquid lubricant such as oil, and the height Hmm at which the liquid after standing for 10 minutes rises in the absorbent body is measured. It can be said that the higher the height Hmm, the higher the “absorbability” of the lubricant.
The evaluation of the “absorbability” of the material is not limited to the above method, and can be selected as appropriate.

  A distance L2 from the inner end of one restricting member 28 to the inner end of the other restricting member 28 is longer than the maximum sheet width that the printer can pass. In the present embodiment, the L2 is 322 mm. In this embodiment, the distance L3 from the outer end portion of one restricting member 28 to the outer end portion of the other restricting member 28 is 350 mm, and the longitudinal length L1: 344 mm of the sliding member 24a. Is also getting longer. That is, the outer end portion of the restricting member 28 is positioned outside the longitudinal end portion of the sliding member 24a.

12 is an enlarged cross-sectional view of a portion surrounded by a broken line D in FIG.
The restricting member 28 includes an attachment portion 28 a for attaching to the nip forming member 24. The attachment portion 28a includes a columnar through portion 281b and a retaining portion 281a. The retaining portion 281a is provided at the tip of the penetrating portion 281b, and has a trapezoidal cross section that increases in diameter from the tip side toward the penetrating portion 281a.

  The nip forming member 24 has a hollow box shape, and has a through-hole whose inner diameter is slightly larger than the outer diameter of the through-portion 281b in the vicinity of the longitudinal end of the wall surface on the upstream side in the rotation direction of the fixing belt of the nip forming member. 241 is formed. The through hole 241a also overlaps with the through hole 241 of the nip forming member 24 in the vicinity of the end in the longitudinal direction of the portion of the sliding member 24a attached to the upstream wall surface of the fixing belt in the rotation direction of the fixing belt. Is provided.

  To attach the regulating member 28, first, the regulating member 28 is pushed into the sliding member 24a side while pressing the tip of the retaining portion 281a against the through hole 241a of the sliding member 24a. Then, the retaining portion 281a is compressed and deformed and inserted into the through hole 241a of the sliding member 24a. Further, when the regulating member 28 is pushed in and the retaining portion 281 exits the through-hole 241 of the nip forming member 24, the retaining portion 281 returns to its original shape. Thereby, the regulating member 28 is attached to the nip forming member 24.

  The restricting member 28 has a substantially L shape such that the outer end portion is positioned upstream of the inner end portion in the rotation direction of the fixing belt. Specifically, the thickness of the inner end portion of the regulating member is T1, the thickness gradually increases from the inner end portion toward the outer side, and the thickness of the outer end portion is T2. Further, the upstream surface of the fixing belt of the regulating member 28 is a gentle R-shaped inclined surface 28b that is located downstream from the outside toward the inside in the fixing belt rotation direction. In the present embodiment, an R-shaped inclined surface is used, but a linear inclined surface may be used.

  As shown in FIG. 11, in this embodiment, the regulating members 28 are provided at both ends in the longitudinal direction of the nip forming member 24. Therefore, it is possible to restrict the lubricant 201 blocked by the upstream end portion of the nip forming member 24 from moving outside the longitudinal end portion of the sliding member 24a. As a result, the lubricant 201 blocked by the upstream end of the nip forming member 24 can be absorbed by the sliding member 24a. As a result, a circulation cycle in which the lubricant 201 attached to the fixing belt 21 from the sliding member 24a returns to the sliding member 24a can be established. Therefore, the decrease in the lubricant contained in the sliding member 24a can be suppressed over time, and the lubricating effect of the lubricant 201 can be maintained over time. As a result, an increase in torque of the fixing device can be suppressed over time.

  Further, the upstream surface of the fixing belt of the regulating member 28 is a gentle R-shaped inclined surface 28b that is located downstream from the outside toward the inside in the fixing belt rotation direction. Thereby, the lubricant adhering to the outer side from the inner end of the regulating member 28 on the inner peripheral surface of the fixing belt 21 from the sliding member 24a can be guided inward by the inclined surface 28b. Further, the lubricant 201 that has moved to the outside from the inner end portion of the regulating member 28 before being blocked by the upstream end portion of the nip forming member can be guided inward by the inclined surface 28b. As a result, the lubricant 201 outside the inner end of the regulating member 28 can be brought into contact with the sliding member 24a and can be absorbed again by the sliding member 24a.

  Since the lubricant 201 does not come into contact with the sliding member 24a outside the inner end portion of the regulating member 28, the lubricant 201 is present in a region outside the inner end portion of the regulating member 28 of the sliding member 24a. Not absorbed. When the sheet passes through the fixing nip N, the contact pressure between the fixing belt 21 and the nip forming member in the sheet passing area is higher than that in the non-sheet passing area. Increases frictional resistance.

  Therefore, in the present embodiment, the regulating member 28 is provided outside the maximum sheet width that the printer can pass. As a result, the lubricant 201 adhering to the fixing belt 21 is absorbed in the paper passing region of the sliding member 24a, and sufficient lubricant 201 can be held at least in the paper passing region of the sliding member 24a. Thereby, the effect of a lubricant can be effectively maintained.

  In the present embodiment, the regulating member 28 is made of fluororubber so that the lubricant 201 is not absorbed by the regulating member 28. When the restricting member 28 is made of a material that can absorb the lubricant 201, the restricting member 28 accumulates the lubricant 201, and the lubricant 201 contained in the sliding member 24a is reduced. May not be obtained. Further, the lubricant 201 absorbed by the regulating member 28 may leak from the outer end portion of the regulating member 28. The lubricant that has leaked from the outer end moves to the outside and may eventually leak from the end of the fixing belt 21.

  The restriction member 28 is made of fluoro rubber so that the lubricant 201 is not absorbed by the restriction member 28, so that the decrease in the lubricant contained in the sliding member 24a can be suppressed, and the outer end portion of the restriction member 28 can be suppressed. Therefore, it is possible to prevent a situation in which the lubricant 201 leaks out.

  Further, by making the regulating member 28 an elastic member such as fluoro rubber, the regulating member 28 can be elastically deformed and brought into contact with the fixing belt. As a result, the regulating member 28 can follow the position fluctuation of the fixing belt, and the regulating member 28 can be brought into contact with the inner peripheral surface of the fixing belt 21 without a gap. As a result, the movement of the lubricant 201 attached to the fixing belt 21 to the outside can be well regulated. The inclined surface 28b can return the lubricant 201 attached to the inner peripheral surface of the fixing belt 21 to the inside.

  Further, as shown in FIG. 12, the outer end portion of the inclined surface 28b of the regulating member 28 is located outside the end portion in the longitudinal direction of the sliding member 24a. As a result, the lubricant 201 adhering to the fixing belt 21 from the vicinity of the end in the longitudinal direction of the sliding member 24a can be caught by the inclined surface 28b of the regulating member 28, and the lubricant 201 can be captured by the inclined surface 28b. It can be returned inward so as to contact 24a. Further, the lubricant that has moved to the outside of the longitudinal end portion of the sliding member 24a can also be captured by the inclined surface 28b, and the lubricant 201 is returned to the inside so as to contact the sliding member 24a at the inclined surface 28b. be able to.

  In the present embodiment, the regulating member 28 is provided at the end portion in the longitudinal direction of the sliding member 24a. This is because if the lubricant adheres to the guide portion 451a, the lubricant 201 cannot be returned to the inside by the regulating member 28. By providing the regulating member inside the tip of the guide portion 451a, the lubricant adhered to the fixing belt can be returned to the inside and can be supplied again to the sliding member 24a. Further, the inner end of the regulating member 28 may be located inside the longitudinal end of the sliding member 24a. Thereby, the lubricant regulated by the regulating member 28 can be returned to the sliding member 24a, and the lubricant 201 adhering to the fixing belt 21 can be supplied again to the sliding member 24a.

  Furthermore, in the present embodiment, the regulating member 28 is provided at a position adjacent to the nip forming member from the upstream side in the rotation direction of the fixing belt, but may be an arbitrary position on the rotation track of the fixing belt. Regardless of the position adjacent to the nip forming member from the upstream side in the rotation direction of the fixing belt, the movement of the lubricant adhering to the fixing belt is restricted to prevent the lubricant from adhering to the guide portion. can do. Further, the lubricant adhering to the fixing belt can be brought into contact with the end of the sliding member on the upstream side in the fixing belt rotation direction by returning the inner side of the longitudinal end of the sliding member 24a with the regulating member. , Can be re-supplied to the sliding member.

  However, when the lubricant 201 is blocked by the upstream end of the sliding member 24a, the lubricant is likely to move outward. Therefore, it is desirable that the regulating member 28 be provided at a position adjacent to the nip forming member from the upstream side in the rotation direction of the fixing belt, so that the movement of the lubricant 201 can be effectively regulated.

Next, a modification of this embodiment will be described.
FIG. 13 is a schematic view of the periphery of the nip forming member 24 in the modified fixing device as viewed from the pressure roller side, and FIG. 14 is an enlarged cross-sectional view of a portion surrounded by a broken line D in FIG.
As shown in FIG. 13, in the first modification, a lubricant collection member 27 that is a lubricant holding member is provided between the regulating members 28. The lubricant recovery member 27 is made of a material having a higher absorbability of the lubricant 201 than the sliding member 24a, such as a superabsorbent polymer.

  As shown in FIG. 14, both ends of the lubricant recovery member 27 are attached to the nip forming member 24 by attachment screws 27a. Thus, by providing the lubricant recovery member 27, the lubricant 201 can be held by the sliding member 24a and the lubricant recovery member 27, and the amount of lubricant that can be held can be increased. Thereby, the lubrication effect by the lubricant can be maintained over time.

  The lubricant adhering to the inner peripheral surface of the fixing belt 21 from the sliding member 24 a and moving to the upstream side in the fixing belt rotation direction of the nip forming member 24 together with the fixing belt is blocked by the lubricant collecting member 27. After that, it is absorbed and recovered by the lubricant recovery member 27. As described above, since the lubricant recovery member 27 is made of a material having a higher absorbability of the lubricant 201 than the sliding member 24a, it can quickly absorb the blocked lubricant.

  The lubricant 201 absorbed by the lubricant recovery member 27 adheres to the inner peripheral surface of the belt, is carried to the sliding member 24a by the rotation of the belt, and is supplied to the sliding member 24a. Further, the lubricant of the lubricant recovery member 27 is supplied to the slide member 24a through the contact portion of the lubricant recovery member 27 with the slide member 24a.

  Further, since the regulating member 28 is provided outside the lubricant collecting member 27, the regulating member 28 regulates the leakage of the lubricant 201 from the longitudinal end portion of the lubricant collecting member 27. Can do. Further, since the outer end portion of the regulating member 28 is located upstream of the lubricant recovery member 27 in the fixing belt rotation direction, the lubricant blocked by the lubricant recovery member 27 moves to the end portion of the fixing belt. Can be restricted.

  Further, the lubricant adhering to the outside of the lubricant recovery member 27 of the fixing belt 21 is guided to the inclined surface 28 b of the regulating member and returned to the lubricant recovery member 27. Thereby, the lubricant adhering to the fixing belt can be recovered by the lubricant recovery member 27.

What was demonstrated above is an example, and there exists an effect peculiar for every following aspect.
(Aspect 1)
A rotatable endless fixing belt 21, a pressure member such as a pressure roller 22 in contact with the outer peripheral surface of the fixing belt 21, and a pressure member disposed on the inner peripheral side of the fixing belt 21 via the fixing belt 21. A nip forming member 24 that forms a nip portion such as a fixing nip portion N, and a sliding member 24a that is provided on the nip forming member 24 so as to contact the inner peripheral surface of the fixing belt 21 and impregnates a lubricant. In the fixing device 20 including the lubricant impregnated member, the lubricant impregnated member that restricts the movement of the lubricant adhering to the fixing belt 21 to the end of the fixing belt 21 inside the both ends of the fixing belt 21. The regulating member 28 having a lower absorbability of the lubricant is provided.
According to this, the movement of the lubricant adhering to the fixing belt 21 to the end is restricted by the restriction member 28. Further, since the regulating member 28 has a lower absorbability of the lubricant than the lubricant-impregnated member such as the sliding member 24a, compared with the case where the absorption rate of the lubricant of the regulating member 28 is equal to or higher than that of the lubricant-impregnated member. Thus, the lubricant can be prevented from being absorbed by the regulating member 28, and the leakage of the lubricant from the outer end of the regulating member 28 in the fixing belt width direction can be suppressed. Thereby, it is possible to satisfactorily suppress the lubricant from leaking from the fixing belt 21.

(Aspect 2)
In (Aspect 1), the regulating member 28 is disposed adjacent to the nip forming member 24 from the upstream side in the rotation direction of the fixing belt 21.
According to this, the movement of the lubricant 201 blocked by the nip forming member 24 to the end portion of the fixing belt 21 can be restricted. Thereby, the lubricant blocked by the nip forming member 24 can be prevented from leaking from the end portion of the fixing belt 21.

(Aspect 3)
In (Aspect 2), a lubricant holding member such as a lubricant recovery member 27 that absorbs and holds the lubricant 201 attached to the fixing belt 21 is provided on the inner side in the width direction of the fixing belt 21 than the regulating member 28. .
According to this, as described in the modification, the lubricant 201 can be held by the lubricant holding member such as the lubricant collecting member 27 and the lubricant impregnated member such as the sliding member 24a. The amount of lubricant that can be increased. Thereby, the lubrication effect by the lubricant can be maintained over time.
Further, since the lubricant holding member is provided on the inner side in the width direction of the fixing belt than the regulating member 28, the lubricant 201 leaking from the end in the width direction of the lubricant holding member is The movement to the end can be regulated by the regulating member 28.

(Aspect 4)
In (Aspect 3), the lubricant holding member such as the lubricant collecting member 27 is made of a material having higher absorbability of the lubricant than the lubricant impregnated member such as the sliding member 24a.
Thereby, the lubricant blocked by the lubricant holding member such as the lubricant recovery member 27 can be quickly absorbed.

(Aspect 5)
In any one of (Aspect 1) to (Aspect 4), the regulating member 28 causes the lubricant adhering to the inner peripheral surface of the fixing belt to pass from the end of the lubricant-impregnated member such as the sliding member 24a in the width direction of the fixing belt. Also has a return portion such as an inclined surface 28b that returns to the inside.
As a result, the lubricant adhering to the outside of the fixing belt in the width direction of the fixing belt of the lubricant impregnating member such as the sliding member 24 a can be removed by the return portion of the regulating member 28. It can return to the inner side of the end in the width direction. As a result, the lubricant adhering to the outside of the end portion in the width direction of the lubricant impregnated member of the fixing belt 21 can be brought into contact with the upstream end portion in the rotation direction of the fixing belt of the lubricant impregnated member. It can be returned to the agent-impregnated member. As a result, the lubricant impregnated member can be impregnated with the lubricant over time, and the lubricating effect of the lubricant can be maintained over time.

(Aspect 6)
In (Aspect 5), the return portion is an inclined surface that is inclined so as to be located on the upstream side in the rotation direction of the fixing belt from the inner end portion in the width direction of the regulating member 28 toward the outer side in the width direction. It is.
According to this, when the lubricant adhering to the inner peripheral surface of the fixing belt 21 comes into contact with the inclined surface 28b of the regulating member, the lubricant moves along the inclined surface 28b and moves inward in the width direction of the fixing belt. Can do.

(Aspect 7)
In (Aspect 5) or (Aspect 6), the outer end in the width direction of the return portion such as the inclined surface 28b is located outside the end in the width direction of the lubricant-impregnated member such as the sliding member 24a. To do.
According to this, the lubricant adhering to the outer side of the end portion in the width direction of the lubricant-impregnated member such as the sliding member 24a on the inner peripheral surface of the fixing belt is transferred to the width of the lubricant-impregnated member at the return portion. It can return to the inner side than the end of the direction.

(Aspect 8)
In any one of (Aspect 5) to (Aspect 7), the inner end portion in the width direction of the regulating member 28 is positioned inside the end portion in the width direction of the lubricant-impregnated member such as the sliding member 24a.
According to this, the lubricant can be returned to the inner side of the end portion in the width direction of the lubricant-impregnated member such as the sliding member 24a at the return portion such as the inclined surface 28b.

(Aspect 9)
In any one of (Aspect 1) to (Aspect 8), among the recording materials such as paper P that can pass through the nip portion such as the fixing nip portion N, the recording material having the maximum length in the width direction of the fixing belt is the nip. The regulating member 28 is provided on the outer side in the width direction with respect to the region in the width direction passing through the portion.
According to this, the lubricant 201 adhering to the fixing belt 21 contacts and is collected by the lubricant-impregnated member at least in the recording material passing region of the lubricant-impregnated member such as the sliding member 24a. Thereby, the lubricant can be held at least in the paper passing region of the lubricant impregnated member. When the paper is passed, the contact pressure with the fixing belt increases in the paper-passing region of the lubricant-impregnated member, and the lubricant is retained in that region, so that the lubricating effect by the lubricant is effectively obtained. be able to.

(Aspect 10)
In any one of (Aspect 1) to (Aspect 9), the regulating member 28 is formed of an elastic member.
According to this, the regulating member 28 can be elastically deformed and brought into contact with the inner peripheral surface of the fixing belt 21 without a gap, and the movement of the lubricant adhering to the fixing belt to the fixing belt end can be well regulated. Can do.

(Aspect 11)
An image carrier such as a photosensitive drum, toner image forming means (in this embodiment, a charging device, a developing device, an optical writing device, etc.) for forming a toner image on the image carrier; A transfer unit such as a transfer device 71 that transfers the image from the image carrier onto a recording material such as paper P, and a fixing unit such as a fixing device 20 that fixes the toner image transferred onto the recording material to the recording material. In the image forming apparatus, the fixing device of any one of (Aspect 1) to (Aspect 10) is used as the fixing unit.
According to this, it is possible to prevent the inside of the apparatus from being contaminated by the lubricant leaking from the fixing device.

6 optical writing device 20 fixing device 21 fixing belt 22 pressure roller 23 heating device 24 nip forming member 24a sliding member 27 lubricant recovery member 28 regulating member 28b inclined surface 30 charging device 40 developing device 71 transfer device 100 image forming device 120 Photosensitive drum 201 Lubricant 451 Flange member 451a Guide portion

JP 2014-174358 A JP 2004-286922 A JP 2010-79309 A JP 2007-334205 A

Claims (11)

A rotatable endless fixing belt;
A pressure member in contact with the outer peripheral surface of the fixing belt;
A nip forming member disposed on the inner peripheral side of the fixing belt and abutting the pressure member via the fixing belt to form a nip portion;
In the fixing device provided with the lubricant impregnating member provided in the nip forming member so as to contact the inner peripheral surface of the fixing belt and impregnating the lubricant,
A regulating member that regulates the movement of the lubricant adhering to the fixing belt to the end portion of the fixing belt inside the both ends of the fixing belt and has a lower absorbability of the lubricant than the lubricant-impregnated member. A fixing device provided. The fixing device according to claim 1,
The fixing device, wherein the regulating member is disposed adjacent to the nip forming member from the upstream side in the rotation direction of the fixing belt. The fixing device according to claim 2,
A fixing device, wherein a lubricant holding member that absorbs and holds a lubricant adhering to the fixing belt is provided inside the fixing belt in a width direction of the regulating member. The fixing device according to claim 3.
The fixing device, wherein the lubricant holding member is made of a material having a higher absorbability of lubricant than the lubricant-impregnated member. The fixing device according to any one of claims 1 to 4,
The fixing device includes a return portion that returns the lubricant adhered to the inner peripheral surface of the fixing belt to the inside of the end portion of the lubricant-impregnated member in the width direction of the fixing belt. In the fixing device according to claim 5,
The return portion is an inclined surface that is inclined so as to be positioned on the upstream side in the rotation direction of the fixing belt from the inner end portion in the width direction of the regulating member toward the outer side in the width direction. Fixing device. In the fixing device according to claim 5 or 6,
The fixing device according to claim 1, wherein an outer end portion in the width direction of the return portion is positioned outside an end portion in the width direction of the lubricant impregnated member. The fixing device according to any one of claims 5 to 7,
The fixing device according to claim 1, wherein an inner end portion in the width direction of the regulating member is positioned inside an end portion in the width direction of the lubricant-impregnated member. The fixing device according to claim 1,
Among the recording materials that can pass through the nip portion, the regulating member is located on the outer side in the width direction than the region in the width direction in which the recording material having the maximum length in the width direction of the fixing belt passes through the nip portion. And a fixing device. The fixing device according to any one of claims 1 to 9,
A fixing device, wherein the regulating member is formed of an elastic member. An 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 onto a recording material;
An image forming apparatus comprising: a fixing unit that fixes the toner image transferred onto the recording material to the recording material;
An image forming apparatus using the fixing device according to claim 1 as the fixing unit.

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