JP2018013518A - Fixing device and image forming apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a fixing device for preventing breakage in a fixing member by a nip forming member, by use of an appropriate amount of a lubricant.SOLUTION: The fixing device includes an endless fixing member 21 having flexibility, a pressurizing member 22 pressing the fixing member and driving the fixing member to rotate, a nip forming member 24 disposed on an inner circumference side of the fixing member and forming a nip N together with the pressurizing member via the fixing member, and a holding member 37 holding the fixing member as rotatable at an end of the fixing member. A lubricant is applied on the inner circumference surface of the fixing member. The device includes: a lubricant scraping part 27e for scraping an excess fraction of the lubricant depositing on the inner circumference surface of the fixing member; and a lubricant accommodating part 27b for accommodating the lubricant scraped by the lubricant scraping part. The fixing member can vary a rotation locus in a period from the start of image formation to the end of image formation, and the inner circumference surface of the fixing member comes into contact with the lubricant accommodated in the lubricant accommodating part at least once by changes in the rotation locus of the fixing member.SELECTED DRAWING: Figure 7

Description

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

  In recent years, there has been a strong market demand for energy saving and high speed for image forming apparatuses such as copiers, printers, facsimiles, and multifunction machines having at least two of these functions.

  Among image forming apparatuses, the fixing apparatus has a large amount of power consumption and a large room for energy saving, and various proposals have been made. For example, a fixing device capable of directly heating a film-like thin endless fixing member (for example, a fixing belt) with a low heat capacity and capable of obtaining good fixing properties even when mounted on a high-production image forming apparatus. It is known (see, for example, Patent Document 1). In the fixing device described in Patent Document 1, a pressure member (for example, a pressure roller) disposed on the outer peripheral side of an endless fixing member, and a nip forming member fixedly disposed inside the fixing member (in a loop) And a press nip through a fixing member to form a fixing nip.

  However, the fixing device described in Patent Document 1 has a problem that the nip forming member keeps rubbing against the inner periphery of the fixing member, thereby damaging the inner peripheral surface of the fixing member and causing damage to the fixing member. .

  On the other hand, in order to reduce the frictional load between the nip forming member and the fixing member, it is common to apply a lubricant to the inner peripheral surface of the fixing member.

  However, when the fixing member rotates and passes through the fixing nip, the lubricant applied to the inner peripheral surface of the fixing member is scraped off by the nip forming member at the inlet and outlet of the fixing nip. The scraped lubricant gradually accumulates outside the fixing nip. Therefore, the amount of lubricant adhering to the inner peripheral surface of the fixing member is reduced, the friction load between the nip forming member and the fixing member is increased, and the fixing member is damaged or the pressure member that rotates the fixing member is damaged. There is a risk of inviting.

  In addition, a lubricant is disposed between the inner peripheral surface of the fixing member and the nip forming member, and a lubricant reservoir portion in which the lubricant is accumulated and an end portion is in contact with or close to the inner peripheral surface of the fixing member. 1 is known that includes a heat shielding member and a lubricant damming member that dams the lubricant on the inner peripheral surface of the fixing member (see, for example, Patent Document 2).

  According to the fixing device described in Patent Document 2, the rotation of the fixing member is hardly inhibited by the contact between the inner peripheral surface of the fixing member and the other end portion of the first heat shielding member, and the lubricant from the lubricant reservoir portion. Is supplied, the fixing member can be smoothly rotated.

  However, in the fixing device described in Patent Document 2, unless the lubricant is constantly supplied, the amount of the lubricant adhering to the inner peripheral surface of the fixing member is reduced, and the friction load between the nip forming member and the fixing member is reduced. May increase, and the fixing member may be damaged.

  An object of the present invention is to provide a fixing device that prevents a fixing member from being damaged by a nip forming member with an appropriate amount of lubricant.

In order to solve the above-described problem, a fixing device according to a first aspect of the present invention includes:
An endless fixing member having flexibility;
A pressure member that presses the fixing member and rotates the driven member;
A nip forming member disposed on an inner peripheral side of the fixing member and forming a nip portion with the pressure member via the fixing member;
A fixing device comprising: a holding member that rotatably holds the fixing member at an end of the fixing member;
A lubricant is applied to the inner peripheral surface of the fixing member,
The nip forming member has a lubricant scraping portion that scrapes off excess lubricant adhering to the inner peripheral surface of the fixing member when the fixing member is conveyed to the nip portion;
A lubricant containing portion for containing the lubricant scraped by the lubricant scraping portion;
The fixing member can change the rotation locus between the start of image formation and the end of image formation.
The inner peripheral surface of the fixing member is in contact with the lubricant stored in the lubricant storage portion at least once by changing the rotation locus of the fixing member.

  According to the present invention, it is possible to provide a fixing device that prevents the fixing member from being damaged by the nip forming member with an appropriate amount of lubricant.

1 is a schematic diagram illustrating an image forming apparatus according to an embodiment of the present invention. 1 is a schematic cross-sectional configuration diagram illustrating an embodiment of a fixing device. FIG. 6 is an explanatory diagram for explaining a fixing belt mounting configuration. FIG. 6 is an explanatory diagram for explaining the behavior of the fixing belt. FIG. 6 is an explanatory diagram for explaining the behavior of the fixing belt. It is explanatory drawing explaining the structure of the conventional heat transfer auxiliary member. It is explanatory drawing explaining the structure of the heat transfer auxiliary member which concerns on 1st Embodiment. It is explanatory drawing explaining the structure of the heat transfer auxiliary member which concerns on 2nd Embodiment.

  Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings. FIG. 1 is a schematic diagram showing an image forming apparatus according to an embodiment of the present invention. The image forming apparatus 1 is a color laser printer, and four image forming units 4Y, 4C, 4M, and 4K are arranged in parallel in the center of the printer main body along the extending direction of the intermediate transfer belt 30. Each of the image forming units 4Y, 4C, 4M, and 4K stores developers of different colors of yellow (Y), cyan (C), magenta (M), and black (K) corresponding to the color separation components of the color image. Other than that, the configuration is the same.

  Specifically, each of the image forming units 4Y, 4C, 4M, and 4K constituting the image station includes a drum-shaped photoconductor 5 as a latent image carrier, a charging device 6 that charges the surface of the photoconductor 5, and A developing device 7 for supplying toner to the surface of the photoreceptor 5 and a cleaning device 8 for cleaning the surface of the photoreceptor 5 are provided. In FIG. 1, only the photoconductor 5, the charging device 6, the developing device 7, and the cleaning device 8 included in the black image forming unit 4 </ b> K are assigned color codes, and the other image forming units 4 </ b> Y, 4 </ b> C, and 4 </ b> M The reference numerals are omitted.

  Below the image forming units 4Y, 4C, 4M, and 4K, an exposure device 9 that exposes the surface of the photoreceptor 5 is disposed. The exposure device 9 includes a light source, a polygon mirror, an f-θ lens, a reflection mirror, and the like, and irradiates the surface of each photoconductor 5 with laser light based on image data.

  A transfer device 3 is disposed above the image forming units 4Y, 4C, 4M, and 4K. The transfer device 3 includes an intermediate transfer belt 30 as a transfer body, four primary transfer rollers 31 as primary transfer means, and a secondary transfer roller 36 as secondary transfer means. Further, the transfer device 3 includes a secondary transfer backup roller 32, a cleaning backup roller 33, a tension roller 34, and a belt cleaning device 35.

  The intermediate transfer belt 30 is an endless belt and is stretched by a secondary transfer backup roller 32, a cleaning backup roller 33, and a tension roller 34. Here, when the secondary transfer backup roller 32 is driven to rotate, the intermediate transfer belt 30 runs (rotates) in the direction indicated by the arrow in the figure.

  Each of the four primary transfer rollers 31 sandwiches the intermediate transfer belt 30 with each photoconductor 5 to form a primary transfer nip. In addition, each primary transfer roller 31 is connected to a power source of a printer main body, and a predetermined DC voltage (DC) and / or AC voltage (AC) is applied to each primary transfer roller 31. .

  The secondary transfer roller 36 sandwiches the intermediate transfer belt 30 with the secondary transfer backup roller 32 to form a secondary transfer nip. Similarly to the primary transfer roller 31, the secondary transfer roller 36 is also connected to the power source of the printer main body, and a predetermined DC voltage (DC) and / or AC voltage (AC) is applied to the secondary transfer roller 36. It has come to be.

  The belt cleaning device 35 includes a cleaning brush and a cleaning blade disposed so as to contact the intermediate transfer belt 30.

  A bottle container 2 is provided in the upper part of the printer main body, and four toner bottles 2Y, 2C, 2M, and 2K containing replenishing toner are detachably attached to the bottle container 2. As is well known, a replenishment path is provided between each toner bottle 2Y, 2C, 2M, 2K and each developing device 7, and each development from each toner bottle 2Y, 2C, 2M, 2K is performed via this replenishment path. The toner is supplied to the device 7.

  On the other hand, a lower portion of the printer main body is provided with a paper feed tray 10 that stores paper P as a recording material, a paper feed roller 11 that carries the paper P out of the paper feed tray 10, and the like. Here, in addition to plain paper, the recording material includes thick paper, postcard, envelope, thin paper, coated paper (coated paper, art paper, etc.), tracing paper, OHP sheet, and the like. Further, as is well known, a manual paper feed mechanism may be provided.

  In the printer main body, a transport path R is provided for discharging the paper P from the paper feed tray 10 through the secondary transfer nip to the outside of the apparatus. In the transport path R, a pair of registration rollers (positioning rollers) 12 serving as transport means for transporting the paper P to the secondary transfer nip is disposed upstream of the position of the secondary transfer roller 36 in the paper transport direction. ing.

  Further, a fixing device 20 for fixing the unfixed image transferred onto the paper P is disposed downstream of the position of the secondary transfer roller 36 in the paper transport direction. Further, a pair of paper discharge rollers 13 for discharging the paper to the outside of the apparatus is provided downstream of the fixing device 20 in the paper conveyance direction of the conveyance path R. In addition, a paper discharge tray 14 for stocking paper discharged outside the apparatus is provided on the upper surface of the printer main body.

  The basic operation of the printer according to this embodiment is as follows. When the image forming operation is started, the photoconductors 5 in the image forming units 4Y, 4C, 4M, and 4K are rotationally driven clockwise in the drawing, and the surface of each photoconductor 5 is set to a predetermined polarity by the charging device 6. Uniformly charged. The surface of each charged photoconductor 5 is irradiated with laser light from the exposure device 9 to form an electrostatic latent image on the surface of each photoconductor 5. At this time, the image information to be exposed on each photoconductor 5 is single-color image information obtained by separating a desired full-color image into color information of yellow, cyan, magenta, and black. In this way, toner is supplied to each electrostatic latent image formed on each photoconductor 5 by each developing device 7, whereby the electrostatic latent image is visualized (visualized) as a toner image. .

  When the image forming operation is started, the secondary transfer backup roller 32 is driven to rotate counterclockwise in the figure, and the intermediate transfer belt 30 is caused to run in the direction indicated by the arrow in the figure. 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 31. As a result, a transfer electric field is formed in the primary transfer nip between each primary transfer roller 31 and each photoconductor 5.

  Thereafter, when each color toner image on the photoconductor 5 reaches the primary transfer nip as each photoconductor 5 rotates, the toner image on each photoconductor 5 is formed by the transfer electric field formed in the primary transfer nip. The images are sequentially superimposed and transferred onto the intermediate transfer belt 30. Thus, a full color toner image is carried on the surface of the intermediate transfer belt 30. Further, the toner on each photoconductor 5 that could not be transferred to the intermediate transfer belt 30 is removed by the cleaning device 8. Thereafter, the surface of each photoconductor 5 is neutralized, and the surface potential is initialized.

  In the lower part of the image forming apparatus, the paper feed roller 11 starts to rotate, and the paper P is sent out from the paper feed tray 10 to the transport path R. The sheet P sent to the conveyance path R is timed by the registration roller 12 and is sent to the secondary transfer nip between the secondary transfer roller 36 and the secondary transfer backup roller 32. At this time, a transfer voltage having a polarity opposite to the toner charge polarity of the toner image on the intermediate transfer belt 30 is applied to the secondary transfer roller 36, thereby forming a transfer electric field in the secondary transfer nip.

  Thereafter, when the toner image on the intermediate transfer belt 30 reaches the secondary transfer nip as the intermediate transfer belt 30 rotates, the toner image on the intermediate transfer belt 30 is generated by the transfer electric field formed in the nip. Are collectively transferred onto the paper P. At this time, the residual toner on the intermediate transfer belt 30 that could not be transferred onto the paper P is removed by the belt cleaning device 35, and the removed toner is conveyed to a waste toner container placed in the printer body. To be recovered.

  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 13 and stocked on the paper discharge tray 14.

  The above description is an image forming operation when a full-color image is formed on a sheet. A single-color image can be formed using any one of the four image forming units 4Y, 4C, 4M, and 4K. Two or three image forming units can be used to form a two-color or three-color image.

  FIG. 2 is a schematic cross-sectional configuration diagram illustrating an embodiment of a fixing device. The fixing device 20 includes a fixing belt 21 that is a thin, flexible, rotatable endless and cylindrical fixing member, and a pressure roller 22 that is a pressure member that abuts from the outer peripheral side of the fixing belt 21. And have. The fixing belt 21 is heated by the radiant heat of the halogen heaters 23A and 23B as a plurality of heat sources arranged inside (in the loop). The halogen heater represents a radiant heat source as a main heat source.

  Further, inside (inside) the fixing belt 21, a nip forming member 24 that forms a fixing nip (nip portion) N with the pressure roller 22 via the fixing belt 21, and a stay member that supports the nip forming member 24. 25 (supporting member). When the nip forming member 24 arranged in the width direction (longitudinal direction) of the fixing belt 21 is fixedly supported by the stay member 25, the nip forming member 24 is bent by the pressure from the pressure roller 22. Thus, a uniform nip width can be obtained in the axial direction (longitudinal direction) of the pressure roller 22. The nip forming member 24 is a heat-resistant member having high mechanical strength and a heat-resistant temperature of 200 ° C. or more, particularly heat-resistant resins such as polyimide (PI) resin, polyether ether ketone (PEEK) resin, and reinforced them with glass fiber. Is made up of. This prevents deformation of the nip forming member 24 due to heat in the toner fixing temperature range, ensures a stable fixing nip state, and stabilizes the output image quality. The stay member 25 and the halogen heaters 23A and 23B are fixedly held at both ends in the longitudinal direction by a side plate of the fixing device 20 or a separately provided holder. End heaters 26 as end heat sources different from the main heat source (fixing heat source) are integrally attached to both ends in the longitudinal direction of the nip forming member 24. As the end heater, a contact heat transfer type heat source that is a resistance heating element such as a ceramic saver is generally used.

  A heat transfer auxiliary member 27, also referred to as a heat equalizing member that loosens the temperature gradient in the longitudinal direction of the fixing belt, covers each surface of the nip forming member 24 and the end heater 26 that faces the inner peripheral surface of the fixing belt 21. Is arranged. The heat transfer auxiliary member 27 is made of a material having high thermal conductivity that enables heat transfer in a short time, such as copper, aluminum, silver, or the like. This prevents heat from staying in the end region of the fixing belt 21 when small-size paper is passed or when the end heater 26 is turned on, and actively moves heat in the longitudinal direction of the heat transfer auxiliary member 27. Thus, the temperature non-uniformity in the longitudinal direction of the fixing belt 21 is eliminated. In the present embodiment, the heat transfer auxiliary member 27 is formed as a component constituting the nip forming member 24, and the surface of the heat transfer auxiliary member 27 that faces the inner peripheral surface of the fixing belt 21 is the fixing belt 21. It is a surface that is in direct contact with the surface, and is a nip forming surface. A lubricant is applied to the inner peripheral surface of the fixing belt 21 to enhance the slidability between the inner peripheral surface of the fixing belt 21 and the heat transfer assisting member 27.

  In the depiction in FIG. 2, the nip forming surface is formed in a flat shape, but may have a concave shape or other shapes. If the nip forming surface has a concave shape, the discharge direction at the front end of the paper is closer to the pressure roller, the separation is improved, and jamming is suppressed.

  As is well known, a temperature sensor 29 for detecting the belt temperature is provided at an appropriate position on the outer peripheral side of the fixing belt 21, for example, upstream of the fixing nip in the belt rotation direction, and downstream of the fixing device 20 in the sheet conveyance direction. On the side, a separating member 41 for separating the paper P from the fixing belt 21 is disposed. Further, releasable pressure means for pressing the pressure roller 22 to the fixing belt 21 is also provided.

  In order to achieve a low heat capacity, the endless fixing belt 21 which is thin and small in diameter like a film is composed of a base material on the inner peripheral side made of a metal material such as nickel or SUS, or a resin material such as polyimide, and a PFA. It is constituted by a release layer on the outer peripheral side formed of (tetrafluoroethylene / perfluoroalkyl vinyl ether copolymer) or PTFE (polytetrafluoroethylene). 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 the unfixed toner is crushed and fixed, the elastic deformation of the elastic layer can absorb minute irregularities on the belt surface and avoid occurrence of uneven gloss. From the viewpoint of reducing the heat capacity, the fixing belt 21 is set to a thickness of 1 mm or less and a diameter of 20 to 40 mm as a whole. The thicknesses of the base material, the elastic layer, and the release layer constituting the fixing belt 21 are set in a range of 20 to 50 μm, 100 to 300 μm, and 10 to 50 μm. Further, in order to reduce the heat capacity, the thickness of the entire fixing belt 21 is preferably 0.2 mm or less, and more preferably 0.16 mm or less, and the diameter is It is desirable to be 30 mm or less.

  The stay member 25 having a T-shaped cross section has an upright portion 25a standing upright on the side opposite to the fixing nip N side, and is arranged so that halogen heaters 23A and 23B as main heat sources are separated by the upright portion 25a. . One of the halogen heaters 23A and 23B has a heat generating portion at the center in the longitudinal direction corresponding to the small size paper, and the other has a heat generating portion at both longitudinal ends corresponding to the large size paper. The halogen heaters 23 </ b> A and 23 </ b> B are configured to generate heat by being output controlled by a power supply unit provided in the printer main body. The output control is performed on the belt surface by a temperature sensor 29 provided on the outer periphery of the fixing belt 21. This is performed based on the temperature detection result. By such heater output control, the temperature of the fixing belt 21 (fixing temperature) can be set to a desired temperature.

  Reflecting members 28A and 28B are disposed between the stay member 25 and the halogen heaters 23A and 23B. As a result, the heating efficiency of the halogen heaters 23A and 23B with respect to the fixing belt 21 is increased, and wasteful energy consumption due to the stay member 25 being heated by the radiant heat from the halogen heaters 23A and 23B can be suppressed. The same effect can be obtained by performing heat insulation or mirror treatment on the surface of the stay member 25 instead of providing the reflecting members 28A and 28B.

  The pressure roller 22 includes a cored bar, an elastic layer made of foamable silicone rubber or fluororubber provided on the surface of the cored bar, and a release layer made of PFA, PTFE or the like provided on the surface of the elastic layer. It is constituted by. At a location where the pressure roller 22 is pressed against the fixing belt 21 by a pressing means such as a spring and is pressed against the fixing belt 21, the elastic layer of the pressure roller 22 is crushed to form a fixing nip N having a predetermined width. The The pressure roller 22 is rotationally driven by a driving source such as a motor provided in the printer main body. When the pressure roller 22 is rotationally driven, the driving force is transmitted to the fixing belt 21 through the fixing nip N, and the fixing belt 21 is driven to rotate. The fixing belt 21 is sandwiched and rotated at the fixing nip N, and travels while being guided by flanges as holding members (to be described later) disposed at both ends other than the fixing nip N.

  In the present embodiment, the pressure roller 22 is a solid roller, but may be a hollow roller. In that case, a heat source such as a halogen heater may be disposed inside the pressure roller 22. The elastic layer may be solid rubber, but if there is no heat source inside the pressure roller, 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.

Next, a fixing belt mounting configuration will be described.
FIG. 3 is an explanatory diagram for explaining a fixing belt mounting structure.

  At the end of the fixing belt 21, there is a flange 37 as a holding member that rotatably holds the fixing belt 21. The flange 37 has an insertion portion 39 that is inserted into the inner peripheral side at the end of the fixing belt 21. The outer diameter of the insertion portion 39 is formed smaller than the inner diameter of the fixing belt 21.

  When there is not enough space between the inner diameter of the fixing belt 21 and the outer diameter of the insertion portion 39, the sliding resistance between the inner peripheral surface of the fixing belt 21 and the outer peripheral surface of the insertion portion 39 increases, and the fixing belt. There is a possibility that the end of 21 may be damaged.

  In the present embodiment, a predetermined interval is provided between the inner diameter of the fixing belt 21 and the outer diameter of the insertion portion 39.

  With such a fixing belt 21 mounting configuration, the number of places where the fixing belt 21 is held can be reduced. Therefore, when the fixing belt 21 performs the rotation operation, particularly at the start of the rotation operation, the fixing belt 21 may positively cause a behavior that does not maintain a perfect circle with a cross-sectional shape as described later. it can. Further, even when the fixing belt 21 exhibits such behavior, the sliding resistance between the inner peripheral surface of the fixing belt 21 and the outer peripheral surface of the insertion portion 39 can be reduced. Further, the number of members that come into contact with the inner peripheral surface of the fixing belt can be reduced, and energy saving can be improved.

  A sliding ring 38 that rotates as the fixing belt 21 rotates may be provided between the longitudinal end of the fixing belt 21 and the flange 37. Thereby, the sliding resistance applied to the longitudinal end portion of the fixing belt 21 can be reduced.

Next, the behavior of the fixing belt will be described.
FIG. 4 is an explanatory diagram for explaining the behavior of the fixing belt. FIG. 5 is an explanatory diagram for explaining the behavior of the fixing belt.

  For example, when the fixing belt 21 starts to rotate, the fixing belt 21 having the above-described mounting configuration positively causes a behavior that does not maintain a perfect circle.

  Specifically, when the fixing belt 21 in the stopped state starts to rotate, as shown by reference numeral 21B in FIG. 4, the entire fixing belt 21 is located above the fixing belt 21 in the stopped state or the stable running state (downstream in the sheet conveying direction). Side) (unstable running state). When the stopped fixing belt 21 starts rotating, as shown by a reference numeral 21C in FIG. 5, the entire fixing belt 21 is located below the stationary or stable running state fixing belt 21 (upstream in the sheet conveyance direction). After the slide, as indicated by reference numeral 21B in FIG. 4, the entire fixing belt 21 may be in a state of sliding upward (unstable running state) from the fixing belt 21 in the stopped state or the stable running state. That is, the fixing belt 21 changes the rotation locus between the start of image formation and the end of image formation. The period from the start of image formation to the end of image formation refers to the period from when the fixing device 20 starts driving (rotation) for image formation to the end of driving (rotation).

  When the fixing belt 21 behaves in this manner, there is a moment when the inner peripheral surface of the fixing belt 21 approaches the heat transfer assisting member 27 on the inlet side of the fixing nip N from the fixing belt 21 in a stopped state or a stable running state. is there. The inlet side of the fixing nip N refers to the upstream side of the fixing nip N in the traveling direction of the fixing belt 21, and the outlet side of the fixing nip N refers to the downstream side of the fixing nip N in the traveling direction of the fixing belt 21.

  In the fixing belt 21, the surface pressure of the fixing nip N, the frictional force between the heat transfer assisting member 27 and the inner peripheral surface of the fixing belt 21, the linear velocity at the start of driving, and the layout of the fixing nip N are horizontal with respect to gravity. Various behaviors are exhibited depending on whether the direction is the vertical direction or the vertical direction. In any case, the inner peripheral surface of the fixing belt 21 is more than the fixing nip N from the fixing belt 21 in the stopped state or the stable running state. There is a moment approaching the heat transfer assisting member 27 on the inlet side.

Next, the structure of the conventional heat transfer auxiliary member will be described.
FIG. 6 is an explanatory view illustrating the configuration of a conventional heat transfer assisting member.

  As shown in FIG. 6, the conventional heat transfer assisting member 27 has a nip forming portion 27a and an extension extending from the end of the nip forming portion 27a on the inlet side of the fixing nip N to the side opposite to the fixing nip N side. And a portion 27c.

  Reference numeral 21A in FIG. 6 indicates the state of the fixing belt 21 in the stopped state or the stable running state. Reference numeral 21 </ b> B in FIG. 6 indicates a state where the fixing belt 21 slides upward from the fixing belt 21 in a stopped state or a stable running state (unstable running state). Reference numeral 21 </ b> C in FIG. 6 indicates a state where the fixing belt 21 slides downward from the fixing belt 21 in a stopped state or a stable running state (unstable running state).

  As shown by reference numeral 21B in FIG. 6, the fixing belt 21 is in a state in which the fixing belt 21 slides above the fixing belt 21 in a stopped state or a stable running state (unstable running state). Although it is somewhat closer to the extended portion 27 c of the movement assisting member 27, it does not approach the vicinity of the extended portion 27 c of the heat transfer assisting member 27.

[First Embodiment]
Next, the structure of the heat transfer auxiliary member of the first embodiment will be described.
FIG. 7 is an explanatory view illustrating the configuration of the heat transfer auxiliary member according to the first embodiment.

  As shown in FIG. 7A, the heat transfer assisting member 27 of the first embodiment includes a nip forming portion 27a and an inner periphery of the fixing belt 21 from the end of the nip forming portion 27a on the inlet side of the fixing nip N. It has an inclined portion 27b that is an example of a lubricant accommodating portion that is inclined along the surface, and an extending portion 27c that extends from the end of the inclined portion 27b to the side opposite to the fixing nip N side. The connecting portion on the fixing nip N side between the nip forming portion 27a and the inclined portion 27b constitutes a lubricant scraping portion 27e. The shape of the heat transfer assisting member 27 on the exit side of the fixing nip N of the nip forming portion 27a may be similar.

  7A and 7B indicates the state of the fixing belt 21 in a stopped state or a stable running state. Reference numeral 21B in FIGS. 7A and 7B indicates a state where the fixing belt 21 slides upward from the fixing belt 21 in a stopped state or a stable running state (unstable running state).

  7A and 7B, the fixing belt 21 slides upward from the fixing belt 21 in a stopped state or a stable running state (unstable running state). Thus, the fixing belt 21 approaches the vicinity of the inclined portion 27 b of the heat transfer auxiliary member 27.

  On the outlet side of the fixing nip N, excessive lubricant may stay, and the staying lubricant adheres to the inner peripheral surface of the fixing belt 21.

  In a state where the fixing belt 21 is rotating stably (stable running state), as indicated by reference numeral 21A in FIG. 7B, the inner peripheral surface of the fixing belt 21 is lubricated on the inlet side of the fixing nip N. The excess lubricant adhering to the inner peripheral surface of the fixing belt 21 in contact with the agent scraping portion 27e is scraped off to form the lubricant reservoir 40 on the inclined portion 27b. Further, in a state where the fixing belt 21 is rotating stably (stable running state), as indicated by reference numeral 21A in FIG. 7B, the fixing belt 21 has a lubricant reservoir formed on the inclined portion 27b. 40 does not touch. As a result, the lubricant is not excessively supplied to the fixing nip N.

  Further, even when the behavior of the rotation of the fixing belt 21 changes due to a change in the linear speed and the inner peripheral surface of the fixing belt 21 comes into contact with the lubricant reservoir 40, The inner peripheral surface comes into contact with the lubricant scraping portion 27e, and excess lubricant adhering to the inner peripheral surface of the fixing belt 21 is scraped off. Therefore, the lubricant is not excessively supplied to the fixing nip N.

  In a state immediately after the stopped fixing belt 21 starts to rotate (unstable running state), the fixing belt 21 is connected to the inclined portion 27b of the heat transfer assisting member 27 as indicated by reference numeral 21B in FIG. The lubricant approaches the vicinity, contacts the lubricant reservoir 40, and the lubricant adheres to the inner peripheral surface of the fixing belt 21. The lubricant adhering to the inner peripheral surface of the fixing belt 21 comes into contact with the lubricant scraping portion 27e, and excess lubricant adhering to the inner peripheral surface of the fixing belt 21 is scraped off. As a result, an appropriate amount of lubricant is supplied to the inner peripheral surface of the fixing belt 21.

  Further, the lubricant on the inner peripheral surface of the fixing belt 21 is collected by the inclined portion 27b of the heat transfer assisting member 27 except for a minute volatile component due to heat to form a lubricant reservoir 40. For this reason, even if the lubricant is not replenished regularly, it can be used continuously until the life of the fixing unit without increasing the sliding resistance of the fixing nip N.

[Second Embodiment]
Next, the structure of the heat transfer auxiliary member according to the second embodiment will be described.
FIG. 8 is an explanatory view illustrating the configuration of the heat transfer auxiliary member according to the second embodiment.

  The heat transfer assisting member of the second embodiment is different from the first embodiment in that it has a concave portion instead of the inclined portion.

  As shown in FIG. 8, the heat transfer assisting member 27 of the second embodiment is separated from the inner peripheral surface of the fixing belt 21 from the nip forming portion 27a and the end portion on the inlet side of the fixing nip N of the nip forming portion 27a. A concave portion 27d that is an example of a lubricant accommodating portion that forms a concave shape in the direction, and an extended portion 27c that extends from the end of the concave portion 27d to the side opposite to the fixing nip N side. A connecting portion on the fixing nip N side between the nip forming portion 27a and the concave portion 27d constitutes a lubricant scraping portion 27e. Lubricant accumulates in the recess 27 d to form a lubricant reservoir 40. The recess 27 d is formed such that the lubricant reservoir 40 is along the inner peripheral surface of the fixing belt 21. The concave portion 27d may be formed so that the lubricant reservoir 40 is formed along the inner peripheral surface of the fixing belt 21, and various shapes can be applied. The shape of the heat transfer assisting member 27 on the exit side of the fixing nip N of the nip forming portion 27a may be the same shape.

  In a state where the fixing belt 21 is rotating stably (stable running state), on the inlet side of the fixing nip N, the inner peripheral surface of the fixing belt 21 comes into contact with the lubricant scraping portion 27e. Excess lubricant adhering to the inner peripheral surface is scraped off, and the lubricant accumulates in the recess 27d. Further, when the fixing belt 21 is rotating stably (stable running state), the fixing belt 21 does not contact the lubricant reservoir 40 accumulated on the recess 27d. As a result, the lubricant is not excessively supplied to the fixing nip N.

  Further, even if the rotation behavior of the fixing belt 21 changes due to a change in the linear velocity or the like, and the inner peripheral surface of the fixing belt 21 comes into contact with the lubricant reservoir 40 accumulated in the concave portion 27d, the fixing belt 21 is moved toward the inlet side of the fixing nip N. The inner peripheral surface of the fixing belt 21 comes into contact with the lubricant scraping portion 27e, and excess lubricant adhering to the inner peripheral surface of the fixing belt 21 is scraped off. Therefore, the lubricant is not excessively supplied to the fixing nip N.

  In the state immediately after the fixing belt 21 in the stopped state starts rotating (unstable running state), the fixing belt 21 has a lubricant deposited in the concave portion 27d of the heat transfer assisting member 27 as indicated by reference numeral 21B in FIG. The lubricant comes into contact with the reservoir 40 and adheres to the inner peripheral surface of the fixing belt 21. The lubricant adhering to the inner peripheral surface of the fixing belt 21 comes into contact with the lubricant scraping portion 27e, and excess lubricant adhering to the inner peripheral surface of the fixing belt 21 is scraped off. As a result, an appropriate amount of lubricant is supplied to the inner peripheral surface of the fixing belt 21.

  Further, the lubricant on the inner peripheral surface of the fixing belt 21 is collected in the concave portion 27d of the heat transfer assisting member 27 except for a minute volatile component due to heat. For this reason, even if the lubricant is not replenished regularly, it can be used continuously until the life of the fixing unit without increasing the sliding resistance of the fixing nip N. Further, it is possible to prevent excessive lubricant from leaking out and contaminating the inside of the apparatus.

  As mentioned above, although this invention was demonstrated based on embodiment, this invention is not limited to embodiment, It can change suitably within the scope of the present invention.

  For example, the surface of the heat transfer auxiliary member 27 that faces the inner peripheral surface of the fixing belt 21 is preferably smooth. Moreover, in order to improve slidability, it is desirable to perform application that reduces the friction coefficient. For example, fluorine-based paint or coating such as PFA or PTFE is applied. Thereby, sliding with the heat transfer auxiliary member 27 and the inner surface of the fixing belt 21 can be maintained satisfactorily. Further, a small amount of lubricant can be provided between the heat transfer assisting member 27 and the inner peripheral surface of the fixing belt 21.

  The image forming apparatus provided with the fixing device of the present invention is not limited to a copying machine or a printer, but may be a facsimile machine or a multifunction machine having a plurality of functions.

20 fixing device 21 fixing belt (an example of a fixing member)
22 Pressure roller (an example of a pressure member)
24 Nip forming member 37 Flange (an example of a holding member)
N Fixing nip (nip part)

JP 2014-174440 A JP 2011-22430 A

Claims (6)

An endless fixing member having flexibility;
A pressure member that presses the fixing member and rotates the driven member;
A nip forming member disposed on an inner peripheral side of the fixing member and forming a nip portion with the pressure member via the fixing member;
A fixing device comprising: a holding member that rotatably holds the fixing member at an end of the fixing member;
A lubricant is applied to the inner peripheral surface of the fixing member,
The nip forming member has a lubricant scraping portion that scrapes off excess lubricant adhering to the inner peripheral surface of the fixing member when the fixing member is conveyed to the nip portion;
A lubricant containing portion for containing the lubricant scraped by the lubricant scraping portion;
The fixing member can change the rotation locus between the start of image formation and the end of image formation.
The fixing device according to claim 1, wherein an inner peripheral surface of the fixing member contacts at least one time with a lubricant stored in the lubricant storage portion by changing a rotation locus of the fixing member. Between the start of image formation and the end of image formation, the fixing member has a stable traveling state in which it travels stably, and the unstable traveling state in which the fixing member travels unstablely,
In the stable running state, the inner peripheral surface of the fixing member is not in contact with the lubricant accommodated in the lubricant accommodating portion,
2. The fixing device according to claim 1, wherein in the unstable running state, the inner peripheral surface of the fixing member contacts at least one time with the lubricant stored in the lubricant storage portion.   The fixing device according to claim 1, wherein the lubricant container is disposed in the nip forming member.   The fixing device according to claim 1, wherein the lubricant accommodating portion is disposed upstream of the nip portion in a rotation direction of the fixing member. The nip forming member has a heat transfer assisting member that makes contact with the inner peripheral surface of the fixing member and loosens a temperature gradient in the longitudinal direction of the fixing member;
The fixing device according to claim 1, wherein the heat transfer auxiliary member includes the lubricant scraping portion and the lubricant accommodating portion.   An image forming apparatus comprising the fixing device according to claim 1.

Images