JP2005148618A - Fixing device and image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To suppress paper wrinkling and form jamming for a long period by stabilizing the recording paper conveying capability of a fixing device. <P>SOLUTION: The fixing device 60 which fixes a toner image carried on a form P is equipped with a rotatable fixing roll 61, an endless belt 62 which can move while coming into contact with the fixing roll 61 to form a nip part N, an pressure pad 64 which is arranged inside the endless belt 62 and presses the endless belt 62 against the fixing roll 61 at the nip part N, a low-friction sheet 68 which is provided between the endless belt 62 and pressure pad 64 and has its length made shorter than the nip part N, and a lubricant coating member 67 which has its length made shorter than the low-friction sheet 68. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a fixing device and the like, and more particularly to a fixing device used in an image forming apparatus using an electrophotographic system.

  In an image forming apparatus such as a copying machine or a printer using an electrophotographic method, for example, a photosensitive member formed in a drum shape is uniformly charged, and the photosensitive member is exposed to light controlled based on image information. An electrostatic latent image is formed on the photoreceptor. The electrostatic latent image is converted into a visible image (toner image) with toner, and the toner image is further transferred onto a recording sheet and fixed by a fixing device to form an image.

  In the fixing device used in such an image forming apparatus, as shown in FIG. 9, a heating source 113 is provided inside a cylindrical metal core 111, and a release layer 112 is formed on the outer peripheral surface of the metal core 111. The fixing roll 110 was pressed against the fixing roll 110, and a heat-resistant elastic body layer 122 and a release layer 123 made of a heat-resistant resin film or heat-resistant rubber film were formed on the outer peripheral surface of the core metal 121. It is composed of a pressure roll 120. Then, the recording paper carrying the unfixed toner image is passed between the fixing roll 110 and the pressure roll 120, and the unfixed toner image is heated and pressed to thereby apply the toner to the recording paper. The image is fixed. Such a fixing device is called a heating roll method and is generally widely used.

By the way, when it is intended to increase the speed of the heating roll type fixing device, it is necessary to widen the nip width in proportion to the fixing speed in order to supply a sufficient amount of heat to the toner and the recording paper. As a method of widening the nip width, there are a method of increasing the load between the fixing roll and the pressure roll, a method of increasing the thickness of the elastic body, and a method of increasing the roll diameter.
However, in the method of increasing the load and the method of increasing the thickness of the elastic body, the uneven nip width and paper wrinkle occur because the shape of the nip width due to the deflection of the roll becomes non-uniform along the roll axis. This causes image quality problems such as In addition, the method of increasing the roll diameter causes problems that the apparatus is increased in size and the time (warm-up time) until the roll is raised from room temperature to a fixable temperature is increased.

  Therefore, in order to solve these problems and realize a fixing device corresponding to the speeding up of the image forming apparatus, the applicant of the present invention has a rotatable fixing roll whose surface is elastically deformed and remains in contact with the fixing roll. An endless belt capable of traveling and a pressure pad arranged in a non-rotating state inside the endless belt, and the endless belt is pressed against the fixing roll so that a contact surface with the fixing roll is formed by the pressure pad. And a belt nip so that the sheet can be passed between the endless belt and the fixing roll, and a fixing device configured to locally elastically deform the exit side of the sheet on the surface of the fixing roll. The technique regarding this is proposed (for example, refer patent document 1).

  In the technique described in Patent Document 1, the endless belt is pressed against the fixing roll using a pressure pad instead of the pressure roll in the conventional heating roll type fixing device. By adopting such a configuration, the width of the belt nip formed by the fixing roll and the endless belt can be easily made larger than the width of the roll nip between the conventional fixing roll and the pressure roll. It is easy to reduce the size of the apparatus.

  In particular, the heat capacity of the endless belt brought into pressure contact with the fixing roll is small, and further, the heat transmitted from the fixing roll is hardly dissipated because the pressure pad is arranged in a non-rotating state. Therefore, even when rotation of the fixing roll is started, the amount of heat taken from the fixing roll to the endless belt side is small, and the efficiency of using heat for melting the toner is increased, and the temperature decrease amount at the belt nip is also small. There is an advantage that the fixing property of the toner can be improved.

Japanese Patent No. 3298354 (pages 4-7)

  By the way, in the fixing device of the type in which the endless belt is pressed against the fixing roll using the pressure pad, the endless belt is used by the pressure pad in order to maintain good transportability of the recording paper passing between the fixing roll and the endless belt. It is necessary to ensure the slipperiness between the pressure pad and the endless belt when the is pressed against the fixing roll. For this purpose, a low friction member is disposed on the pressure pad, and a lubricant is applied to the inner peripheral surface of the endless belt to supply the lubricant to the sliding portion between the low friction member and the endless belt. Reduction of frictional resistance (frictional resistance) with the belt is attempted.

However, since pressure is applied between the pressure pad and the endless belt, a part of the lubricant applied to the inner peripheral surface of the endless belt enters the sliding portion between the endless belt and the low friction member. A phenomenon occurs in which the lubricant that cannot enter and gradually accumulates in the entrance region of the sliding portion. As the endless belt rotates repeatedly, the retained lubricant spreads at both ends in the sliding portion entrance region and leaks to the outside, and is gradually applied to the inner peripheral surface of the endless belt. The amount decreases. Therefore, there is a tendency that the slipperiness between the low friction member and the endless belt gradually decreases. Furthermore, due to the decrease in the amount of lubricant, the friction surface between the low friction member and the endless belt is likely to be worn, and the slipping property between the low friction member and the endless belt may be further reduced.
Under such circumstances, the frictional resistance between the pressure pad and the endless belt tends to increase with the use of the fixing device. There is a disadvantage that the transportability is not good, and there is a high possibility that paper wrinkles and paper jam will occur.

  Accordingly, the present invention has been made to solve the technical problems as described above. The object of the present invention is to stabilize the recording paper conveyance capability in the fixing device, and thereby to make the paper wrinkle over a long period of time. And to suppress the occurrence of paper jams.

  For this purpose, the fixing device of the present invention is a fixing device for fixing a toner image carried on a recording material, and a rotatable rotating member, and a nip portion formed in contact with the rotating member. A movable endless belt, a pressure member that is disposed inside the endless belt, presses the endless belt against the rotating member at the nip portion, and is provided between the endless belt and the pressure member, and the longitudinal direction is the nip portion. And a lubricant application member whose longitudinal direction is shorter than that of the sliding member.

Here, a belt guide member that supports the endless belt from the inner peripheral surface side is arranged at both ends of the endless belt, and the longitudinal direction of the sliding member with respect to the lubricant held by the endless belt in this belt guide member. It can comprise so that it may have the surface which controls the expansion beyond the width | variety of a direction.
Further, the sliding member may be characterized in that irregularities are formed on a sliding surface with the endless belt. Furthermore, the sliding member can also be configured to have a difficult passage through the lubricant. In particular, the sliding member is composed of a base layer made of porous fibers and a resin layer disposed on the surface opposite to the rubbing surface of the base layer with the endless belt and having difficulty in passing through the lubricant. can do.

  The fixing device of the present invention is a fixing device for fixing a toner image carried on a recording material, and is movable while forming a nip portion in contact with the rotating member and a rotating member. An endless belt, a pressure member that is disposed inside the endless belt, presses the endless belt against the rotating member at the nip portion, a sliding member provided between the endless belt and the pressure member, and an endless belt. A lubricant application member for applying a lubricant to the peripheral surface, and the end of the lubricant application member is located on the inner side in the longitudinal direction from the end of the slide member, and the end of the slide member is It is characterized by being located on the inner side in the longitudinal direction than the end of the nip portion.

Here, the rotating member may be a fixing roll having a heat source inside and elastically deforming the surface. Furthermore, the pressure member may be characterized by locally elastically deforming the downstream side in the rotational direction of the surface of the fixing roll.
Moreover, it can also be set as the structure further equipped with the belt guide member which regulates the deviation of an endless belt in the both ends of an endless belt. Furthermore, it can also be set as the structure further provided with the lubricant control member which controls the spreading | diffusion beyond the width | variety of the longitudinal direction of a sliding member with respect to the lubricant hold | maintained at the endless belt.
Furthermore, the lubricant application member may be characterized in that the edge abuts against the inner peripheral surface of the endless belt.

The fixing device of the present invention is a fixing device for fixing a toner image carried on a recording material, and is movable while forming a nip portion in contact with the rotating member and a rotating member. An endless belt, a pressure member that is disposed inside the endless belt, presses the endless belt against the rotating member at the nip portion, a sliding member provided between the endless belt and the pressure member, and an endless belt. And a lubricant application member that applies lubricant to the peripheral surface, and the sliding member is disposed so as to include a region where the lubricant is applied by the lubricant application member, and the nip portion slides. It is characterized in that it is formed so as to include a region where the member is arranged. Here, the “region” refers to a region in the longitudinal direction of the fixing device.
Here, the sliding member can be characterized by having regions where the lubricant is not applied by the lubricant application member on both sides of the sliding member. Further, the nip portion may have a region where no sliding member is disposed on both sides of the nip portion.

Further, the fixing device of the present invention has a pressure roll that can be elastically deformed, a rotatable pressure belt, a heat generating source, a fixing belt that can be driven while being in contact with the pressure roll and forming a nip portion, A pressure member that is disposed inside the fixing belt and presses the fixing belt against the pressure roll at the nip portion, a sliding member provided between the fixing belt and the pressure member, and a lubricant on the inner peripheral surface of the fixing belt And the end of the lubricant applying member is located on the inner side in the longitudinal direction from the end of the sliding member, and the end of the sliding member is the end of the nip portion. It is characterized by being located on the inner side in the longitudinal direction.
Here, the pressure member can also be constituted by a heat source disposed on the fixing belt.

Further, the present invention is regarded as an image forming apparatus. The image forming apparatus of the present invention includes a toner image forming unit that forms a toner image, and a transfer unit that transfers the toner image formed by the toner image forming unit onto a recording material. A fixing means for fixing the toner image transferred onto the recording material to the recording material, the fixing means being movable while being able to contact the rotating member and forming a nip portion in contact with the rotating member. Endless belt, a pressure member that is arranged inside the endless belt, presses the endless belt against the rotating member in the nip portion, and is provided between the endless belt and the pressure member, and the longitudinal direction is shorter than the nip portion. And a lubricant application member whose longitudinal direction is shorter than that of the sliding member.
Here, the fixing unit may further include a lubricant restricting member that suppresses the lubricant held by the endless belt from being expanded beyond the width of the sliding member in the longitudinal direction. Further, the fixing unit may be configured such that the sliding member has irregularities on the sliding surface with the endless belt.

  As an effect of the present invention, it is possible to provide an image forming apparatus capable of suppressing the occurrence of paper wrinkles and paper jams over a long period of time by stabilizing the recording paper conveyance capability in the fixing device.

Embodiments of the present invention will be described below in detail with reference to the accompanying drawings.
[Embodiment 1]
FIG. 1 is a schematic configuration diagram illustrating an image forming apparatus to which the exemplary embodiment is applied. The image forming apparatus shown in FIG. 1 is an intermediate transfer type image forming apparatus generally called a tandem type, and a plurality of image forming units 1Y, 1M, 1C, and 1K on which toner images of respective color components are formed by electrophotography. The primary transfer unit 10 that sequentially transfers (primary transfer) the color component toner images formed by the image forming units 1Y, 1M, 1C, and 1K to the intermediate transfer belt 15, and the superimposed toner image transferred onto the intermediate transfer belt 15. Are provided with a secondary transfer unit 20 that collectively transfers (secondary transfer) to a paper P that is a recording material (recording paper), and a fixing device 60 that fixes the secondary transferred image onto the paper P. Moreover, it has the control part 40 which controls operation | movement of each apparatus (each part).

  In the present embodiment, each of the image forming units 1Y, 1M, 1C, and 1K has a charger 12 that charges the photosensitive drum 11 around the photosensitive drum 11 that rotates in the direction of arrow A, and the photosensitive drum 11. A laser exposure device 13 for writing an electrostatic latent image thereon (exposure beam is indicated by a symbol Bm in the figure), each color component toner is accommodated, and the electrostatic latent image on the photosensitive drum 11 is visualized with toner. A developing unit 14, a primary transfer roll 16 that transfers each color component toner image formed on the photosensitive drum 11 to the intermediate transfer belt 15 in the primary transfer unit 10, and a drum cleaner that removes residual toner on the photosensitive drum 11. 17 and the like are sequentially arranged. These image forming units 1Y, 1M, 1C, and 1K are arranged in a substantially straight line from the upstream side of the intermediate transfer belt 15 in the order of yellow (Y), magenta (M), cyan (C), and black (K). Has been.

The intermediate transfer belt 15 as an intermediate transfer member is constituted by a film-like endless belt in which an appropriate amount of an antistatic agent such as carbon black is contained in a resin such as polyimide or polyamide. And the volume resistivity is formed so that it may become 10 < ⁶ > -10 < ¹⁴ > (omega | ohm) cm, The thickness is comprised by about 0.1 mm, for example. The intermediate transfer belt 15 is circulated and driven (rotated) at a predetermined speed in the direction B shown in FIG. 1 by various rolls. As these various rolls, a drive roll 31 that is driven by a motor (not shown) having excellent constant speed and rotates the intermediate transfer belt 15, and an intermediate that extends substantially linearly along the arrangement direction of the photosensitive drums 11. A support roll 32 that supports the transfer belt 15, a tension roll 33 that functions as a correction roll that applies a constant tension to the intermediate transfer belt 15 and prevents meandering of the intermediate transfer belt 15, and a backup provided in the secondary transfer unit 20. A cleaning backup roll 34 provided in a cleaning unit for scraping off residual toner on the roll 25 and the intermediate transfer belt 15 is provided.

The primary transfer unit 10 includes a primary transfer roll 16 that is disposed to face the photosensitive drum 11 with the intermediate transfer belt 15 interposed therebetween. The primary transfer roll 16 includes a shaft and a sponge layer as an elastic layer fixed around the shaft. The shaft is a cylindrical bar made of metal such as iron or SUS. The sponge layer is a sponge-like cylindrical roll formed of a blend rubber of NBR, SBR and EPDM containing a conductive agent such as carbon black and having a volume resistivity of 10 ^7.5 to 10 ^8.5 Ωcm. The primary transfer roll 16 is placed in pressure contact with the photosensitive drum 11 with the intermediate transfer belt 15 in between, and the primary transfer roll 16 has a voltage (with negative polarity; the same applies hereinafter) having a polarity opposite to that of the toner. (Primary transfer bias) is applied. As a result, the toner images on the respective photosensitive drums 11 are sequentially electrostatically attracted to the intermediate transfer belt 15 so as to form superimposed toner images on the intermediate transfer belt 15.

The secondary transfer unit 20 includes a secondary transfer roll 22 disposed on the toner image carrying surface side of the intermediate transfer belt 15 and a backup roll 25. The backup roll 25 is composed of a tube of EPDM and NBR blend rubber with carbon dispersed on the surface, and EPDM rubber on the inside. And it is formed so that the surface resistivity may be 10 ⁷ to 10 ¹⁰ Ω / □, and the hardness is set to, for example, 70 ° (Asker C: manufactured by Kobunshi Keiki Co., Ltd., the same shall apply hereinafter). The backup roll 25 is disposed on the back side of the intermediate transfer belt 15 to form a counter electrode of the secondary transfer roll 22, and a metal power supply roll 26 to which a secondary transfer bias is stably applied is disposed in contact with the backup roll 25. ing.

On the other hand, the secondary transfer roll 22 includes a shaft and a sponge layer as an elastic layer fixed around the shaft. The shaft is a cylindrical bar made of metal such as iron or SUS. The sponge layer is a sponge-like cylindrical roll formed of a blend rubber of NBR, SBR and EPDM containing a conductive agent such as carbon black and having a volume resistivity of 10 ^7.5 to 10 ^8.5 Ωcm. The secondary transfer roll 22 is disposed in pressure contact with the backup roll 25 with the intermediate transfer belt 15 interposed therebetween. Further, the secondary transfer roll 22 is grounded, and a secondary transfer bias is formed between the secondary transfer roll 22 and the backup roll 25. The toner image is secondarily transferred onto the paper P conveyed to the transfer unit 20.

  Further, on the downstream side of the secondary transfer portion 20 of the intermediate transfer belt 15, an intermediate transfer belt that removes residual toner and paper dust on the intermediate transfer belt 15 after the secondary transfer and cleans the surface of the intermediate transfer belt 15. A cleaner 35 is provided so as to be able to contact and separate. On the other hand, on the upstream side of the yellow image forming unit 1Y, a reference sensor (home position sensor) 42 that generates a reference signal serving as a reference for taking image forming timings in the image forming units 1Y, 1M, 1C, and 1K. It is arranged. Further, an image density sensor 43 for adjusting image quality is disposed on the downstream side of the black image forming unit 1K. The reference sensor 42 recognizes a predetermined mark provided on the back side of the intermediate transfer belt 15 and generates a reference signal. Each image forming unit is instructed by an instruction from the control unit 40 based on the recognition of the reference signal. 1Y, 1M, 1C, and 1K are configured to start image formation.

  Further, in the image forming apparatus according to the present embodiment, as a paper transport system, a paper tray 50 that stores paper P, a pickup roll 51 that picks up and transports the paper P accumulated in the paper tray 50 at a predetermined timing, and a pickup A transport roll 52 that transports the paper P fed by the roll 51, a transport chute 53 that feeds the paper P transported by the transport roll 52 to the secondary transfer unit 20, and transported after being secondarily transferred by the secondary transfer roll 22. A conveyance belt 55 that conveys the paper P to be fixed to the fixing device 60 and a fixing inlet guide 56 that guides the paper P to the fixing device 60 are provided.

  Next, a basic image forming process of the image forming apparatus according to the present embodiment will be described. In an image forming apparatus as shown in FIG. 1, image data output from an image reading device (IIT) not shown or a personal computer (PC) not shown is subjected to predetermined image processing by an image processing device (IPS) not shown. After being applied, the image forming operation is executed by the image forming units 1Y, 1M, 1C, and 1K. In IPS, the input reflectance data is subjected to predetermined image processing such as shading correction, position shift correction, brightness / color space conversion, gamma correction, frame deletion, color editing, moving editing, and other various image editing. Is done. The image data that has undergone image processing is converted into color material gradation data of four colors, Y, M, C, and K, and is output to the laser exposure unit 13.

  The laser exposure unit 13 irradiates the photosensitive drums 11 of the image forming units 1Y, 1M, 1C, and 1K, for example, with an exposure beam Bm emitted from a semiconductor laser in accordance with the input color material gradation data. Yes. In each of the photosensitive drums 11 of the image forming units 1Y, 1M, 1C, and 1K, the surface is charged by the charger 12, and then the surface is scanned and exposed by the laser exposure unit 13 to form an electrostatic latent image. The formed electrostatic latent images are developed as toner images of respective colors Y, M, C, and K by the respective image forming units 1Y, 1M, 1C, and 1K.

  The toner images formed on the photosensitive drums 11 of the image forming units 1Y, 1M, 1C, and 1K are transferred onto the intermediate transfer belt 15 in the primary transfer unit 10 where the photosensitive drums 11 and the intermediate transfer belt 15 come into contact with each other. Transcribed. More specifically, in the primary transfer portion 10, a voltage (primary transfer bias) having a polarity opposite to the toner charging polarity (minus polarity) is applied to the base material of the intermediate transfer belt 15 by the primary transfer roll 16, and the toner image. Are sequentially superimposed on the surface of the intermediate transfer belt 15 to perform primary transfer.

  After the toner images are sequentially primary transferred onto the surface of the intermediate transfer belt 15, the intermediate transfer belt 15 moves and the toner image is conveyed to the secondary transfer unit 20. When the toner image is transported to the secondary transfer unit 20, in the paper transport system, the pick-up roll 51 rotates in accordance with the timing at which the toner image is transported to the secondary transfer unit 20, and the paper of a predetermined size is transferred from the paper tray 50. P is supplied. The paper P supplied by the pickup roll 51 is transported by the transport roll 52 and reaches the secondary transfer unit 20 via the transport chute 53. Before reaching the secondary transfer unit 20, the paper P is temporarily stopped, and a registration roll (not shown) rotates in accordance with the movement timing of the intermediate transfer belt 15 on which the toner image is carried. And the position of the toner image are aligned.

  In the secondary transfer unit 20, the secondary transfer roll 22 is pressed against the backup roll 25 via the intermediate transfer belt 15. At this time, the sheet P conveyed at the same timing is sandwiched between the intermediate transfer belt 15 and the secondary transfer roll 22. At this time, when a voltage (secondary transfer bias) having the same polarity as the toner charging polarity (negative polarity) is applied from the power supply roll 26, a transfer electric field is formed between the secondary transfer roll 22 and the backup roll 25. Is done. The unfixed toner image carried on the intermediate transfer belt 15 is collectively electrostatically transferred onto the paper P in the secondary transfer unit 20 pressed by the secondary transfer roll 22 and the backup roll 25. .

Thereafter, the sheet P on which the toner image has been electrostatically transferred is transported as it is while being peeled off from the intermediate transfer belt 15 by the secondary transfer roll 22, and transported downstream of the secondary transfer roll 22 in the sheet transport direction. It is conveyed to the belt 55. The conveyance belt 55 conveys the paper P to the fixing device 60 in accordance with the optimum conveyance speed in the fixing device 60. The unfixed toner image on the paper P conveyed to the fixing device 60 is fixed on the paper P by being subjected to a fixing process by heat and pressure by the fixing device 60. Then, the paper P on which the fixed image is formed is conveyed to a paper discharge placement unit provided in a discharge unit of the image forming apparatus.
On the other hand, after the transfer onto the paper P is completed, the residual toner remaining on the intermediate transfer belt 15 is conveyed to the cleaning unit as the intermediate transfer belt 15 rotates, and the cleaning backup roll 34 and the intermediate transfer belt cleaner 35 are transferred. Is removed from the intermediate transfer belt 15.

  Next, the fixing device 60 used in the image forming apparatus of the present embodiment will be described. FIG. 2 is a side sectional view showing a configuration of the fixing device 60 of the present embodiment. The fixing device 60 includes a fixing roll 61 as an example of a rotating member, an endless belt 62, and a pressure pad 64 as an example of a pressure member pressed from the fixing roll 61 via the endless belt 62. .

The fixing roll 61 is configured by laminating a heat-resistant elastic layer 612 and a release layer 613 around a metal core (cylindrical core) 611.
Inside the fixing roll 61, a halogen heater 66 is disposed as a heat source. On the other hand, a temperature sensor 69 is disposed in contact with the surface of the fixing roll 61. The control unit 40 of the image forming apparatus controls the lighting of the halogen heater 66 based on the temperature measurement value by the temperature sensor 69 so that the surface temperature of the fixing roll 61 maintains a predetermined set temperature (for example, 170 ° C.). It is adjusted to.
The endless belt 62 is rotatably supported by a pressure pad 64 and an edge guide 80 described later. The nip portion N is disposed in pressure contact with the fixing roll 61.

The pressure pad 64 is disposed inside the endless belt 62 while being pressed against the fixing roll 61 via the endless belt 62, and forms a nip portion N with the fixing roll 61. Here, the nip portion N is a region where the endless belt 62 and the fixing roll 61 are in contact with each other, and is a region extending in a longitudinal direction having a predetermined length in the moving direction of the endless belt 62 and the fixing roll 61. . Therefore, the region in the longitudinal direction of the nip portion N refers to the shorter one of the endless belt 62 and the fixing roll 61.
In the pressure pad 64, a pre-nip member 64a for securing a wide nip portion N (the length in the moving direction of the endless belt 62 and the fixing roll 61) is arranged on the inlet side of the nip portion N, and the fixing roll 61 is distorted. Is provided on the outlet side of the nip portion N. Further, in order to reduce the frictional resistance between the inner peripheral surface of the endless belt 62 and the pressure pad 64, the surface of the pre-nip member 64a and the peeling nip member 64b in contact with the endless belt 62 has a low friction as an example of a rubbing member. A sheet 68 is provided. The pressure pad 64 and the low friction sheet 68 are held by a metal holder 65.

  The fixing roll 61 is rotated in the direction of arrow C by a drive motor (not shown), and the endless belt 62 is also rotated by this rotation. The sheet P on which the toner image is electrostatically transferred in the secondary transfer unit 20 of the image forming apparatus shown in FIG. 1 is guided by the fixing inlet guide 56 and conveyed to the nip N. When the paper P passes through the nip portion N, the toner image on the paper P is fixed by the pressure acting on the nip portion N and the heat supplied from the fixing roll 61. In the fixing device 60 of the present embodiment, since the nip portion N can be configured widely by the concave pre-nip member 64a that substantially follows the outer peripheral surface of the fixing roll 61, stable fixing performance can be ensured.

In addition, in the fixing device 60 of the present embodiment, the separation nip member 64 b is disposed so as to protrude from the outer peripheral surface of the fixing roll 61, so that the fixing roll 61 has an outlet region (peeling nip portion). It can also be configured such that the distortion is locally increased. If the separation nip member 64b is arranged in this way, the fixed paper P passes through the locally formed distortion when passing through the separation nip portion, and therefore is wound around the fixing roll 61. The sheet P can be effectively peeled off.
In particular, by locally increasing the distortion of the fixing roll 61, it is possible to obtain high peeling performance with a small amount of distortion. Therefore, even when a thin heat-resistant resin is used as the release layer 613 of the fixing roll 61, generation of paper wrinkles on the paper P can be suppressed. Further, peeling between the heat-resistant elastic layer 612 and the release layer 613 hardly occurs, and the reliability of the component performance over a long period can be improved together with maintaining the peeling performance.

Furthermore, since the distortion amount of the fixing roll 61 can be reduced, the heat-resistant elastic body layer 612 of the fixing roll 61 can be thinned. Therefore, since the heat capacity of the fixing roll 61 can be reduced, the warm-up time can be shortened and the power consumption can be reduced. Further, since the heat-resistant elastic body layer 612 having a low thermal conductivity can be thinned, the thermal resistance between the inner surface and the outer surface of the fixing roll 61 can be reduced and the thermal responsiveness can be improved. It is also suitable for conversion.
Note that a peeling member 70 may be disposed on the downstream side of the nip portion N of the fixing roll 61 as an auxiliary means for peeling. The peeling member 70 is held by a holder 72 in a state in which the peeling baffle 71 is close to the fixing roll 61 in a direction (counter direction) opposite to the rotation direction of the fixing roll 61.

Next, each member constituting the fixing device 60 will be described in detail. First, in the fixing roll 61, the core 611 is formed of a cylindrical body made of a metal having high thermal conductivity such as iron, aluminum, and SUS. The outer diameter and thickness of the core 611 can be reduced in diameter and thickness in the fixing device 60 of the present embodiment because the pressing force of the pressure pad 64 is small.
Any material can be used for the heat-resistant elastic layer 612 as long as it is an elastic body having high heat resistance. In particular, it is preferable to use an elastic body such as rubber or elastomer having a rubber hardness of about 25 to 40 ° (JIS-A), and specific examples include silicone rubber and fluorine rubber.

  The release layer 613 may be any resin as long as it is a heat resistant resin. For example, a silicone resin, a fluorine resin, or the like can be used. From the viewpoint of safety, a fluororesin is suitable. As the fluororesin, PFA, PTFE (polytetrafluoroethylene), FEP (tetrafluoroethylene hexafluoropropylene copolymer), or the like can be used. The thickness of the release layer 613 is preferably 5 to 30 μm, more preferably 10 to 20 μm. If the thickness of the release layer 613 is less than 5 μm, the paper P is likely to be wrinkled due to the distortion of the fixing roll 61, while if it exceeds 30 μm, the release layer 613 becomes hard and the image has defects such as uneven gloss. This is because there is an increase in the possibility of the occurrence of both.

The endless belt 62 is an endless belt whose original shape is formed in a cylindrical shape. The endless belt 62 includes a base layer and a release layer coated on the surface or both surfaces of the base layer on the fixing roll 61 side. The base layer is formed of a polymer such as polyimide, polyamide, or polyimideamide, or a metal such as SUS, nickel, or copper, and has a thickness of 30 to 200 μm, preferably 50 to 125 μm, and more preferably about 75 to 100 μm. The release layer coated on the surface of the base layer is formed of a fluororesin such as PFA, PTFE, or FEP, and has a thickness of about 5 to 100 μm, preferably about 10 to 30 μm.
Further, the inner peripheral surface of the endless belt 62 has a surface roughness Ra (arithmetic average roughness) set to 0.4 μm or less in order to reduce the frictional resistance with the pressure pad 64. Further, the outer peripheral surface of the endless belt 62 is set to have a surface roughness Ra of 1.2 to 2.0 μm so that the driving force from the fixing roll 61 is easily received.

As described above, the pressure pad 64 includes the pre-nip member 64 a and the peeling nip member 64 b and is supported by the holder 65. An elastic body such as silicone rubber or fluorine rubber, a leaf spring, or the like can be used for the prenip member 64 a, and the surface on the fixing roll 61 side is formed in a concave shape that substantially follows the outer peripheral surface of the fixing roll 61.
The peeling nip member 64b is formed of a heat-resistant resin such as PPS (polyphenylene sulfide), polyimide, polyester, polyamide, or a metal such as iron, aluminum, or SUS. As the shape of the peeling nip member 64b, the outer surface shape in the nip portion N is formed in a convex curved surface shape having a constant radius of curvature.

The low friction sheet 68 is provided to reduce the frictional resistance (friction resistance) between the inner peripheral surface of the endless belt 62 and the pressure pad 64, and is formed of a material having a small friction coefficient and excellent wear resistance and heat resistance. It is suitable to do. Further, minute unevenness is formed on the surface of the low friction sheet 68 on the endless belt 62 side so that the lubricant applied to the inner peripheral surface of the endless belt 62 can enter the sliding portion with the endless belt 62. Yes. The roughness of the irregularities is formed such that Ra (arithmetic mean roughness) is 5 to 30 μm. This is not appropriate if the roughness of the unevenness is smaller than Ra = 5 μm, and it is not appropriate because it is difficult to allow a sufficient lubricant to enter the sliding portion with the endless belt 62. This is based on the fact that the mark is not preferable because it is noticeable as uneven gloss when OHP or coated paper is fixed. Furthermore, the low-friction sheet 68 is configured so as not to infiltrate the lubricant (difficult to pass through) so that the lubricant does not penetrate and leak from the back surface. Specifically, a porous resin fiber cloth made of a fluororesin is used as a base layer, and a surface of the pressure pad 64 is wrapped with a PET resin sheet, a sintered PTFE resin sheet, and Teflon (trade name) are impregnated. A glass fiber sheet or the like can be used.
The low friction sheet 68 may be configured separately from the pre-nip member 64a and the peeling nip member 64b, or may be configured integrally with the pre-nip member 64a and the peeling nip member 64b.

  The holder 65 is provided with a lubricant application member 67 along the longitudinal direction of the fixing device 60. The lubricant application member 67 is made of heat-resistant felt, and is impregnated with about 3 g of a lubricant such as amino-modified silicone oil having a viscosity of 300 cs, for example. The lubricant application member 67 is disposed so as to be in contact with the inner peripheral surface of the endless belt 62, and always supplies an appropriate amount of lubricant to the inner peripheral surface of the endless belt 62 by osmotic pressure from the heat-resistant felt. . The lubricant application member 67 is configured such that only the edge portion of the heat resistant felt is in contact with the inner peripheral surface of the endless belt 62 so that the supply of lubricant from the heat resistant felt is not excessive. Thus, the lubricant is supplied to the sliding portion between the endless belt 62 and the low friction sheet 68, and the friction resistance between the endless belt 62 and the pressure pad 64 via the low friction sheet 68 is further reduced, so that the endless belt 62 is smoothly rotated.

Next, a configuration for supporting the endless belt 62 in the fixing device 60 of the present embodiment will be described. FIG. 3 is a cross-sectional view of the end portion of the fixing device 60 for explaining a state where the endless belt 62 is supported, and is a view seen from the downstream side in the transport direction of the paper P.
As shown in FIG. 3, edge guides 80 are disposed at both ends of the holder 65. The edge guide 80 is provided outside the belt traveling guide portion 801 and the belt traveling guide portion 801 having a cylindrical shape in which a notch is formed in a portion corresponding to the nip portion N and the vicinity thereof, that is, a C-shaped cross section, and an endless belt. A flange portion 802 formed with an outer diameter larger than the inner diameter of 62 and a holding portion 803 provided outside the flange portion 802 for positioning and fixing the edge guide 80 to the fixing device 60 main body. .
Both ends of the holder 65 are fixed and supported on the inner side surface of the flange portion 802. Further, the belt traveling guide portion 801 is disposed so as to overlap with a certain region of the end portion of the holder 65.

The endless belt 62 is supported by the outer peripheral surface of the belt traveling guide portion 801 except for the nip portion N and the vicinity thereof, and rotates along the outer peripheral surface of the belt traveling guide portion 801. (See also FIG. 2). Accordingly, the belt traveling guide portion 801 is formed of a material having a small coefficient of static friction so that the endless belt 62 can smoothly rotate, and further has a thermal conductivity so that it is difficult to take heat away from the endless belt 62. Made of low material.
Further, the flange portion 802 is disposed such that the interval between the inner side surfaces of the flange portion 802 disposed at both ends of the holder 65 substantially coincides with the width of the endless belt 62, and the endless belt 62 moves in the width direction ( Belt walk) is regulated. As described above, the endless belt 62 is configured such that the movement in the rotation direction and the width direction is restricted by the edge guide 80.
The endless belt 62, except for the nip portion N, is made of only the lubricant application member 67 and the edge guide 80, so that the frictional resistance can be made as small as possible, and heat loss is also reduced. Can be small.

  In the fixing device 60 of the present embodiment, the region where the low friction sheet 68 is disposed is in the region of the nip portion N, and the region where the lubricant applying member 67 is disposed is disposed in the low friction sheet 68. It is characterized in that it is configured to be within the region. 4 is a perspective view of one end of the fixing device 60. As shown in FIG. 4, the lubricant application member 67 is formed so that the length in the longitudinal direction is shorter than the length of the low friction sheet 68. In addition, the low friction sheet 68 is formed so that the length in the longitudinal direction is shorter than the length of the nip portion N. As a positional relationship with respect to the longitudinal direction, the end of the lubricant application member 67 is more than the end of the low friction sheet 68. The end portion of the low friction sheet 68 is set to be inside the end portion of the nip portion N. With this configuration, the loss of lubricant from the endless belt 62 can be suppressed, so that it is possible to maintain the lubricant applied to the inner peripheral surface of the endless belt 62 at a predetermined amount, and for a long time. Thus, the endless belt 62 can be smoothly rotated. As a result, it is possible to suppress the occurrence of paper wrinkles and paper jams over a long period until the life of the fixing device 60 is reached.

As described above, the paper P on which the toner image has been electrostatically transferred passes through the nip portion N of the fixing device 60, whereby the toner image is fixed to the paper P, but when the paper P passes through the nip portion N. Is received from the fixing roller 61 on the driving side. That is, the paper P is conveyed by receiving a frictional force from the fixing roll 61 as the fixing roll 61 rotates.
On the other hand, in a state where the sheet P is not conveyed to the nip portion N, the driven endless belt 62 is also rotated by receiving a frictional force from the fixing roll 61 as the fixing roll 61 rotates. However, in a state where the paper P is conveyed to the nip portion N and the paper P is nipped by the nip portion N, the endless belt 62 receives the conveying force from the fixing roll 61 via the paper P. Accordingly, when viewed from the sheet P side, when the sheet P passes through the nip portion N, the sheet P receives a conveying force from the fixing roll 61 and a force in the direction opposite to the conveying direction from the endless belt 62 side. (Reverse conveying force) will act.

By the way, since the pressure pad 64 is pressed in the nip portion N of the endless belt 62, a force in the direction opposite to the rotation direction acts as a frictional resistance from the pressure pad 64. Therefore, as described above, the low friction sheet 68 is interposed between the endless belt 62 and the pressure pad 64, and the lubricant is applied from the lubricant applying member 67 to the inner peripheral surface of the endless belt 62, so The friction resistance between the belt 62 and the pressure pad 64 is configured to be reduced as much as possible.
Therefore, in a normal state, the sliding resistance received by the endless belt 62 from the pressure pad 64 is extremely small and can be smoothly rotated. Therefore, the endless belt 62 can rotate at the same speed as the paper P. . In this case, the reverse conveying force received by the paper P is a rubbing resistance from the pressure pad 64 via the endless belt 62 and is at a level that can be ignored. Therefore, the paper P is stably conveyed at the same speed as the fixing roll 61.

However, since the pressure pad 64 and the fixing roll 61 are pressed, a part of the lubricant applied to the inner peripheral surface of the endless belt 62 is slid between the endless belt 62 and the low friction sheet 68. Some of the lubricant that cannot enter the moving part stays in the entrance region of the sliding part. As the endless belt 62 continues to rotate, the accumulated lubricant gradually spreads to both end sides in the sliding portion entrance region and leaks from both side portions of the endless belt 62. Therefore, the amount of lubricant applied to the inner peripheral surface of the endless belt 62 gradually decreases.
If the amount of lubricant applied to the inner peripheral surface of the endless belt 62 is insufficient, slipperiness (increase in frictional resistance) occurs between the low friction sheet 68 and the endless belt 62. When the rubbing resistance between the endless belt 62 and the pressure pad 64 increases, the reverse conveying force that the sheet P receives from the pressure pad 64 via the endless belt 62 when the sheet P is conveyed through the nip portion N is ignored. It becomes bigger than it can. For this reason, the conveyance of the paper P cannot follow the rotation of the fixing roll 61, and the smooth conveyance of the paper P is hindered, causing paper wrinkles and paper jams in the paper P.

  In particular, in the nip portion N, the fixing roll 61 has a so-called reverse crown shape in which the outer diameter of the fixing roll 61 is increased from the central portion to both ends, or the pressing force between the pre-nip member 64a and the fixing roll 61 is the central portion. By setting so as to increase from the center to the both ends, a force is always applied to the paper P in the width direction from the center to the both ends, thereby preventing the paper P from wrinkling. . However, when the sliding resistance between the endless belt 62 and the pressure pad 64 increases, the paper P cannot follow the conveyance of the fixing roll 61, and the balance of the forces acting in the width direction of the paper P is lost. Therefore, paper wrinkles are generated on the paper P, and further paper jam occurs.

Therefore, in the fixing device 60 of the present embodiment, the region where the low friction sheet 68 is disposed is configured to be within the region of the nip portion N, and the region where the lubricant application member 67 is disposed is the low friction sheet. 68, the leakage of the lubricant from the endless belt 62 is suppressed, and the amount of lubricant applied to the inner peripheral surface of the endless belt 62 is stably maintained. Yes.
Here, the positional relationship in the longitudinal direction with respect to the nip portion N, the low friction sheet 68, and the lubricant application member 67 and the relationship with the region where the lubricant adheres on the inner peripheral surface of the endless belt 62 will be described.
First, as described above, the lubricant application member 67 is disposed so as to contact the inner peripheral surface of the endless belt 62, and a lubricant such as amino-modified silicone oil is constantly supplied to the inner peripheral surface of the endless belt 62. Yes. On the other hand, when the endless belt 62 circulates and returns to the arrangement position of the lubricant application member 67, it also has a function of collecting the lubricant applied to the inner peripheral surface of the endless belt 62. As described above, the lubricant applying member 67 always applies a certain amount of lubricant to the inner surface of the endless belt 62 simultaneously by collecting and supplying the lubricant. The amount of lubricant retained is also kept constant.

The endless belt 62 to which the lubricant is applied by the lubricant applying member 67 is rotated and conveyed to the nip portion N. Under the pressing force between the pressure pad 64 and the endless belt 62 in the nip portion N, However, since the surface of the low friction sheet 68 on the endless belt 62 side has minute irregularities, most of the lubricant applied to the endless belt 62 enters the recesses of the low friction sheet 68. The low friction sheet 68 and the endless belt 62 are supplied to the sliding portion. However, there is a lubricant that cannot enter the sliding portion between the endless belt 62 and the low friction sheet 68 due to the pressing force between the pressure pad 64 and the endless belt 62. For this reason, the lubricant that cannot enter gradually accumulates in the entrance region of the sliding portion, and the retained lubricant gradually expands on both end sides in the sliding portion entrance region.
Note that the amount of lubricant applied to the endless belt 62 can be controlled to a predetermined amount by the lubricant applying member 67, but if the amount of application is controlled so that no stagnation occurs in the entrance region of the sliding portion. In this case, for example, when the coating amount is reduced due to the low viscosity of the lubricant when the image forming apparatus is started up, the supply amount to the sliding portion between the low friction sheet 68 and the endless belt 62 is insufficient. Therefore, it is appropriate to set the coating amount to such an extent that some stagnation occurs in the sliding portion entrance region.

In the fixing device 60 according to the present embodiment, the region where the lubricant applying member 67 is disposed is within the region where the low friction sheet 68 is disposed in the longitudinal positional relationship. FIG. 5 is a diagram illustrating the relationship between the region where the lubricant application member 67 is disposed (lubricant application region) and the region where the low friction sheet 68 is disposed. As shown in FIG. 5, on the inner peripheral surface of the endless belt 62, the end of the region where the lubricant is applied by the lubricant application member 67 (lubricant application region), and the low friction sheet 68 A region where no lubricant is applied from the lubricant application member 67 is set between the end portions. Accordingly, in the region where the lubricant is not applied on both sides of the low friction sheet 68, the lubricant is not directly supplied from the lubricant application member 67 via the endless belt 62. However, as shown in FIG. 5, since the lubricant staying in the sliding portion entrance region spreads on both ends, the staying lubricant supplies the lubricant to both sides of the low friction sheet 68. That is, since the lubricant is not applied to the inner peripheral surface of the endless belt 62 or very little at both sides of the low friction sheet 68, the endless belt 62 spreads on both sides of the low friction sheet 68. The lubricant can be received, and the staying lubricant can be conveyed to the sliding portion with the low friction sheet 68 as the endless belt 62 rotates.
In this way, by providing a region where the lubricant is not applied by the lubricant applying member 67 on the inner peripheral surface of the endless belt 62 at positions corresponding to both sides of the low friction sheet 68, the endless belt 62 and the low friction sheet The lubricant staying in the entrance region of the sliding portion between the sheet 68 and the low friction sheet 68 is conveyed to the sliding portion between the endless belt 62 and the low friction sheet 68 on both sides of the low friction sheet 68, so that the sliding portion Leakage of lubricant that cannot enter can be suppressed.

Further, the fixing device 60 of the present embodiment is configured such that the region where the low friction sheet 68 is disposed is within the region of the nip portion N in the positional relationship in the longitudinal direction. Here, FIG. 6 is a diagram illustrating the relationship between the region where the low friction sheet 68 is disposed and the region of the nip portion N. As shown in FIG. 6, regions where the low friction sheet 68 is not located are set on both sides of the nip portion N.
In the nip portion N, since the pressing force is applied by the pressure pad 64 and the endless belt 62, the force that pushes out the lubricant entering the sliding portion between the low friction sheet 68 and the endless belt 62 from the nip portion N. Act. Therefore, as shown in FIG. 6, the lubricant may ooze out from both ends of the low friction sheet 68. At that time, in the region where the low friction sheets 68 provided on both sides of the nip portion N are not located, the inner peripheral surface of the endless belt 62 is not coated with the lubricant, or the amount of the lubricant is extremely small, so that it oozes out. The lubricant can be collected on the inner peripheral surface of the endless belt 62. Therefore, even if the lubricant that has entered the sliding portion between the low friction sheet 68 and the endless belt 62 is pushed out by the pressing force of the nip portion N, leakage to the outside can be suppressed.
In particular, the endless belt 62 is supported by the outer peripheral surface of the belt traveling guide portion 801 at the inner peripheral surfaces of both sides, and rotates along the outer peripheral surface of the belt traveling guide portion 801 (see FIG. 2). Since the lubricant collected on the inner peripheral surface is held on the contact surface with the outer peripheral surface of the belt traveling guide portion 801, it is difficult to leak to the outside. Further, since the outer peripheral surface of the belt traveling guide portion 801 is formed orthogonal to the inner peripheral surface of the flange portion 802, the movement of the lubricant is also restricted on the inner peripheral surface of the flange portion 802. Leakage is even less likely to occur.

By the way, the lubricant supplied to the sliding portion between the low friction sheet 68 and the endless belt 62 is partially separated from the inner periphery of the endless belt 62 as the endless belt 62 rotates when leaving the nip portion N. It is reapplied to the surface, conveyed to the lubricant application member 67 and collected. In this way, the lubricant is recycled. Therefore, in the fixing device 60 according to the present embodiment, since leakage of the lubricant to the outside can be suppressed, there is almost no loss of the lubricant when the lubricant is circulated and the inner peripheral surface of the endless belt 62 has a long period of time. A predetermined amount of lubricant can be stably supplied.
Note that, on the downstream side of the nip portion N, the region is rotated in a state where the reapplied lubricant is held in a region corresponding to the position where the low friction sheet 68 is disposed on the inner peripheral surface of the endless belt 62. Therefore, in the fixing device 60 of the present embodiment, as shown in FIG. 3, the edge surface 801 a of the belt traveling guide portion 801 is set to substantially coincide with the end portion position of the low friction sheet 68. By setting in this way, as shown in FIG. 7, the lubricant held corresponding to the arrangement position of the low friction sheet 68 on the inner peripheral surface of the endless belt 62 is removed from the edge surface of the belt traveling guide portion 801. Since it is suppressed by 801a that it spreads to both ends, it is also suppressed that the collect | recovered lubricant leaks outside from the inner peripheral surface of the endless belt 62.

  As described above, in the fixing device 60 of the present embodiment, the region where the low friction sheet 68 is disposed is in the region of the nip portion N, and the region where the lubricant applying member 67 is disposed is the low friction sheet. 68 is configured to be within a region in which 68 is arranged. By configuring in this way, it is possible to suppress the loss of the lubricant from the endless belt 62, so that the circulating use of the lubricant applied to the inner peripheral surface of the endless belt 62 can be maintained. Thus, the endless belt 62 can be smoothly rotated. As a result, it is possible to suppress the occurrence of paper wrinkles and paper jams over a long period until the life of the fixing device 60 is reached.

[Embodiment 2]
In the first embodiment, the image forming apparatus is described in which the fixing roll 61 having a heat source is used as the heating unit and the fixing device 60 using the endless belt 62 with the pressure pad 64 pressed as the pressing unit is mounted. In the second embodiment, a fixing device mounted on the image forming apparatus shown in FIG. 1 is a fixing device using a fixing belt with a heat generation source pressed as a heating unit and a pressure roll as a pressing unit. explain. In addition, about the structure similar to Embodiment 1, the same code | symbol is used and the detailed description is abbreviate | omitted here.

FIG. 8 is a side sectional view showing a configuration of the fixing device 90 in the present embodiment. As shown in FIG. 8, in the fixing device 90 of the present embodiment, the fixing belt 92 is disposed on the toner image carrying surface side of the paper P. A ceramic heater 82 which is a resistance heating element as an example of a heat source is disposed inside the fixing belt 92, and heat is supplied from the ceramic heater 82 to the nip portion N.
The ceramic heater 82 has a substantially flat surface on the pressure roll 91 side and is disposed over the entire width of the fixing region. The nip portion N is formed by being supported by the holder 65 and being pressed by the pressure roll 91 via the fixing belt 92. Therefore, the ceramic heater 82 also functions as a pressure member. The sheet P that has passed through the nip portion N is peeled off from the fixing belt 92 by the change in the curvature of the fixing belt 92 in the exit region (peeling nip portion) of the nip portion N. Here, the nip portion N is an area where the fixing belt 92 and the pressure roll 91 are in contact with each other, and is in a longitudinal direction having a predetermined length in the moving direction of the fixing belt 92 and the pressure roll 91. This refers to the area that spans. Therefore, the region in the longitudinal direction of the nip portion N is the shorter one of the fixing belt 92 and the pressure roll 91.

Further, a low friction sheet 68 as an example of a sliding member is provided between the inner peripheral surface of the fixing belt 92 and the ceramic heater 82 in order to reduce the sliding resistance between the inner peripheral surface of the fixing belt 92 and the ceramic heater 82. Is arranged. The low friction sheet 68 may be configured separately from the ceramic heater 82 or may be configured integrally with the ceramic heater 82.
In addition, the lubricant application member 67 is supported on the holder 65 at a position opposite to the position where the ceramic heater 82 is supported. The lubricant application member 67 is made of heat-resistant felt, and is impregnated with about 3 g of a lubricant such as amino-modified silicone oil having a viscosity of 300 cs, for example. The lubricant application member 67 is disposed so as to be in contact with the inner peripheral surface of the fixing belt 92, and always supplies an appropriate amount of lubricant to the inner peripheral surface of the fixing belt 92 by osmotic pressure from the heat-resistant felt. . Note that the lubricant application member 67 is configured such that only the edge portion of the heat resistant felt is in contact with the inner peripheral surface of the fixing belt 92 so that the supply of the lubricant from the heat resistant felt is not excessive. Thus, the lubricant is supplied to the sliding portion between the fixing belt 92 and the low friction sheet 68, and the friction resistance between the fixing belt 92 and the ceramic heater 82 via the low friction sheet 68 is further reduced, so that the fixing belt 92 is smoothly rotated.
Further, the lubricant application member 67 also has a function of collecting the lubricant applied to the inner peripheral surface of the fixing belt 92 when the fixing belt 92 circulates and returns to the position where the lubricant application member 67 is disposed. Have. Thus, the lubricant application member 67 always applies a certain amount of lubricant to the lubricant application member 67 by simultaneously collecting and supplying the lubricant to the inner peripheral surface of the fixing belt 92. The amount of lubricant retained is also kept constant.

On the other hand, the pressure roll 91 is disposed so as to face the fixing belt 92, and is configured to rotate in the direction of arrow D by a drive motor (not shown), so that the fixing belt 92 is driven to rotate. The pressure roll 91 includes a core (cylindrical cored bar) 911, a heat-resistant elastic body layer 912 coated on the outer peripheral surface of the core 911, and a release layer 913 made of a heat-resistant resin coating or a heat-resistant rubber coating. Has been configured. In the fixing device 90 of the present embodiment, the fixing belt 92 is an endless belt whose original shape is formed in a cylindrical shape, and is formed of a polymer such as polyimide, polyamide, or polyimideamide, or a metal such as SUS, nickel, or copper. And a release layer that is formed by PFA, PTFE, or FEP and is coated on the surface or both surfaces of the base layer on the pressure roll 91 side.
Further, a peeling member 70 can be disposed on the downstream side of the nip portion N of the fixing belt 92 as an auxiliary means for peeling. The peeling member 70 is held by the holder 72 in a state where the peeling baffle 71 is close to the fixing belt 92 in a direction (counter direction) opposite to the rotation direction of the fixing belt 92.

  The paper P on which the toner image has been electrostatically transferred in the secondary transfer unit 20 of the image forming apparatus shown in FIG. 1 is guided to the nip N of the fixing device 90 by the fixing inlet guide 56. When the paper P passes through the nip portion N, the toner image on the paper P is fixed by the pressure acting on the nip portion N and the heat supplied from the ceramic heater 82 on the fixing belt 92 side. Also in the fixing device 90 of the present embodiment, since the nip portion N can be configured widely between the pressure roll 91 and the ceramic heater 82, stable fixing performance can be ensured.

Here, in the fixing device 90 of the present embodiment, the region where the low friction sheet 68 is disposed is in the region of the nip portion N, and the region where the lubricant applying member 67 is disposed is disposed in the low friction sheet 68. It is comprised so that it may become in the area | region made.
With this configuration, a region where the lubricant is not applied by the lubricant application member 67 can be provided on the inner peripheral surface of the fixing belt 92 at a position corresponding to both side portions of the low friction sheet 68, and fixing can be performed. The lubricant staying in the sliding portion entrance region between the belt 92 and the low friction sheet 68 is conveyed to the sliding portion between the fixing belt 92 and the low friction sheet 68 on both sides of the low friction sheet 68. Thus, leakage of the lubricant that cannot enter the sliding portion between the fixing belt 92 and the low friction sheet 68 can be suppressed.
Further, by providing a region where the low friction sheet 68 is not located on the inner peripheral surface of the fixing belt 92 at a position corresponding to both sides of the nip portion N, the lubricant exuding from the nip portion N is removed from the inner periphery of the fixing belt 92. It is possible to collect on the surface. Therefore, even if the lubricant that has entered the sliding portion between the low friction sheet 68 and the fixing belt 92 is pushed out by the pressing force of the nip portion N, leakage to the outside can be suppressed.

  As described above, in the fixing device 90 of the present embodiment, the loss of the lubricant from the fixing belt 92 can be suppressed, so that the circulation use of the lubricant applied to the inner peripheral surface of the fixing belt 92 is maintained. The fixing belt 92 can be smoothly rotated over a long period of time. As a result, it is possible to suppress the occurrence of paper wrinkles and paper jams over a long period until the life of the fixing device 90 is reached.

  As an application example of the present invention, application to an image forming apparatus such as a copying machine or a printer using an electrophotographic method, for example, application to a fixing apparatus that fixes an unfixed toner image carried on a recording paper (paper). is there. Further, there is application to an image forming apparatus such as a copying machine or a printer using an ink jet method, for example, to a fixing device that dries an undried ink image carried on a recording paper (paper).

1 is a schematic configuration diagram showing an image forming apparatus of the present invention. 2 is a side cross-sectional view illustrating a configuration of a fixing device according to Embodiment 1. FIG. It is sectional drawing of the edge part of the fixing device explaining the state by which the endless belt was supported. FIG. 3 is a perspective view of an end portion of the fixing device. It is a figure explaining the relationship between the area | region (lubricant application area | region) where a lubricant application member is arrange | positioned, and the area | region where a low friction sheet is arrange | positioned. It is a figure explaining the relationship between the area | region where a low friction sheet | seat is arrange | positioned, and the area | region of a nip part. It is a figure explaining the state by which the spreading of a lubricant is suppressed by the edge surface of a belt run guide part. FIG. 4 is a side sectional view illustrating a configuration of a fixing device according to a second embodiment. FIG. 10 is a side sectional view showing a configuration of a conventional fixing device.

Explanation of symbols

1Y, 1M, 1C, 1K ... image forming unit, 11 ... photosensitive drum, 12 ... charger, 13 ... laser exposure device, 14 ... developing device, 15 ... intermediate transfer belt, 16 ... primary transfer roll, 17 ... drum cleaner 20 ... secondary transfer section, 60,90 ... fixing device, 61 ... fixing roll, 62 ... endless belt, 64 ... pressure pad, 64a ... pre-nip member, 64b ... peeling nip member, 65 ... holder, 66 ... halogen heater, 67 ... Lubricant application member, 68 ... Low friction sheet, 69 ... Temperature sensor, 70 ... Release member, 80 ... Edge guide, 801 ... Belt running guide part, 802 ... Flange part, 803 ... Holding part, 82 ... Ceramic heater, 91 ... Pressure roll, 92 ... Fixing belt

Claims (19)

A fixing device for fixing a toner image carried on a recording material,
A pivotable pivot member;
An endless belt movable in contact with the rotating member while forming a nip portion;
A pressure member that is disposed inside the endless belt and presses the endless belt against the rotating member at the nip portion;
A sliding member provided between the endless belt and the pressure member, the longitudinal direction of which is shorter than the nip portion;
And a lubricant application member having a longitudinal direction shorter than the sliding member.   A belt guide member is provided at both ends of the endless belt and supports the endless belt from the inner peripheral surface side, and the belt guide member slides against the lubricant held by the endless belt. The fixing device according to claim 1, further comprising a surface that restricts the expansion of the member beyond a longitudinal width.   The fixing device according to claim 1, wherein the sliding member has irregularities formed on a sliding surface with the endless belt.   The fixing device according to claim 1, wherein the sliding member is difficult to pass through a lubricant.   The sliding member includes a base layer made of a porous fiber and a resin layer disposed on a surface opposite to the rubbing surface of the base layer with the endless belt and having difficulty in passing through the lubricant. 5. The fixing device according to claim 4, wherein the fixing device is configured. A fixing device for fixing a toner image carried on a recording material,
A pivotable pivot member;
An endless belt movable in contact with the rotating member while forming a nip portion;
A pressure member that is disposed inside the endless belt and presses the endless belt against the rotating member at the nip portion;
A sliding member provided between the endless belt and the pressure member;
A lubricant application member for applying a lubricant to the inner peripheral surface of the endless belt,
The end portion of the lubricant application member is located on the inner side in the longitudinal direction than the end portion of the sliding member, and the end portion of the sliding member is located on the inner side in the longitudinal direction than the end portion of the nip portion. A fixing device characterized.   The fixing device according to claim 6, wherein the rotating member is a fixing roll having a heat source inside and having a surface elastically deformed.   The fixing device according to claim 7, wherein the pressure member locally elastically deforms the downstream side in the rotation direction of the surface of the fixing roll.   The fixing device according to claim 6, further comprising a belt guide member that is disposed at both ends of the endless belt and regulates a deviation of the endless belt.   The fixing device according to claim 6, further comprising a lubricant restricting member that restricts the lubricant held by the endless belt from extending to a width in a longitudinal direction of the sliding member.   The fixing device according to claim 6, wherein an edge of the lubricant application member abuts against an inner peripheral surface of the endless belt. A fixing device for fixing a toner image carried on a recording material,
A pivotable pivot member;
An endless belt movable in contact with the rotating member while forming a nip portion;
A pressure member that is disposed inside the endless belt and presses the endless belt against the rotating member at the nip portion;
A sliding member provided between the endless belt and the pressure member;
A lubricant application member for applying a lubricant to the inner peripheral surface of the endless belt,
The sliding member is disposed so as to include a region where the lubricant is applied by the lubricant applying member, and the nip portion is formed so as to include a region where the sliding member is disposed. A fixing device characterized.   The fixing device according to claim 12, wherein the sliding member has regions where the lubricant is not applied by the lubricant applying member on both sides.   The fixing device according to claim 12, wherein the nip portion has a region where the sliding member is not disposed on both sides. While the surface is elastically deformed, the pressure roll can be rotated,
A fixing belt having a heat source and being driven while being in contact with the pressure roll and forming a nip portion;
A pressure member that is disposed inside the fixing belt and presses the fixing belt against the pressure roll at the nip portion;
A sliding member provided between the fixing belt and the pressure member;
A lubricant application member for applying a lubricant to the inner peripheral surface of the fixing belt,
The end portion of the lubricant application member is located on the inner side in the longitudinal direction than the end portion of the sliding member, and the end portion of the sliding member is located on the inner side in the longitudinal direction than the end portion of the nip portion. A fixing device characterized.   The fixing device according to claim 15, wherein the pressure member includes a heat source disposed on the fixing belt. Toner image forming means for forming a toner image;
Transfer means for transferring the toner image formed by the toner image forming means onto a recording material;
Fixing means for fixing the toner image transferred onto the recording material to the recording material,
The fixing means is
A pivotable pivot member;
An endless belt movable in contact with the rotating member while forming a nip portion;
A pressure member that is disposed inside the endless belt and presses the endless belt against the rotating member at the nip portion;
A sliding member provided between the endless belt and the pressure member, the longitudinal direction of which is shorter than the nip portion;
An image forming apparatus comprising: a lubricant application member having a longitudinal direction shorter than the sliding member.   18. The fixing unit further includes a lubricant regulating member that suppresses expansion of the lubricant held by the endless belt beyond a width in the longitudinal direction of the sliding member. Image forming apparatus.   The image forming apparatus according to claim 17, wherein the fixing unit has irregularities on a sliding surface of the sliding member with the endless belt.

Images