JP6674654B2 - Fixing device and image forming device - Google Patents

Description

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

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

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

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

  It is desired that the sliding sheet be impregnated with as much lubricant as possible so that the lubrication effect of the lubricant can be obtained over time. However, when the sliding sheet is impregnated with a large amount of lubricant, when the sliding sheet is pressed by a pressure roller via a fixing belt, the lubricant impregnated in the sliding sheet is slid. There is a possibility that the sheet leaks from the end of the fixing belt in the width direction.

In order to solve the above-described problems, the present invention provides a rotatable endless fixing belt, a nip forming member disposed on the inner peripheral side of the fixing belt, and the fixing belt being interposed between the nip forming member. A pressure member that is disposed so as to oppose the fixing belt and presses the fixing belt toward the nip forming member so that a nip portion is formed between the nip forming member and the fixing belt; And a lubricant impregnating member for impregnating a lubricant between the lubricant impregnating member and the nip forming member. A lubricant holding member having a high lubricant holding force , disposed between the lubricant holding member and the lubricant impregnated member, for supplying the lubricant of the lubricant holding member to the lubricant impregnated member; Communication hole A lubricant non-absorbing member having a lower lubricant absorptivity than the lubricant impregnated member, wherein the lubricant non-absorbing member is a heat equalizing member for equalizing the temperature in the width direction of the fixing belt. it is characterized in that.

  ADVANTAGE OF THE INVENTION According to this invention, a fixing belt can be rotated smoothly over time, and it can suppress that a lubricant leaks from the fixing belt width direction edge part of a lubricant impregnation member.

FIG. 1 is a schematic configuration diagram of an image forming apparatus according to an embodiment. FIG. 2 is a cross-sectional view of the fixing device according to the embodiment. FIG. 6 is a diagram illustrating a temperature distribution in a width direction of a fixing belt 21 of a conventional example without a heat equalizing member and a temperature distribution in a width direction of the fixing belt of the present embodiment with a heat equalizing member. FIG. 4 is a diagram for explaining adhesion of a lubricant impregnated in a sliding sheet to an inner peripheral surface of a fixing belt. FIG. 3 is a perspective view showing a flange as a belt holding member that holds the fixing belt, and a fixing belt. The figure explaining the characteristic part of this embodiment. The figure explaining the modification 1. The figure explaining the modification 2. The figure explaining the modification 3. The figure explaining the modification 4.

Hereinafter, an embodiment in which the present invention is applied to an image forming apparatus will be described.
In each of the drawings for describing the embodiments of the present invention, components such as members and components having the same function or shape are described once by assigning the same reference numerals as much as possible after discrimination. Then, the description is omitted.

FIG. 1 is a schematic configuration diagram of an image forming apparatus 1 according to the present embodiment.
The image forming apparatus 1 shown in FIG. 1 is a color laser printer, and four image forming units 4Y, 4M, 4C, and 4K are provided at the center of the apparatus main body. Each of the image forming units 4Y, 4M, 4C, and 4K stores developers of different colors of yellow (Y), magenta (M), cyan (C), and black (K) corresponding to the color separation components of the color image. The configuration is the same except for the above.

  Specifically, each of the image forming units 4Y, 4M, 4C, and 4K 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 photoconductor 5 on the surface of the photoconductor 5. A developing device 7 for supplying toner, a cleaning device 8 for cleaning the surface of the photoconductor 5 and the like 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 4K are denoted by reference numerals, and the other image forming units 4Y, 4M, and 4C are denoted by reference numerals. Symbols are omitted.

  An exposure device 9 for exposing the surface of the photoconductor 5 is disposed below each of the image forming units 4Y, 4M, 4C, and 4K. The exposure device 9 has a light source, a polygon mirror, an f-θ lens, a reflection mirror, and the like, and irradiates a laser beam to the surface of each photoconductor 5 based on image data.

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

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

  Each of the four primary transfer rollers 31 forms a primary transfer nip by sandwiching the intermediate transfer belt 30 with each of the photoconductors 5. A power supply is connected to each primary transfer roller 31, and at least one of a predetermined DC voltage (DC) and an alternating voltage (AC) is applied to each primary transfer roller 31. .

  The secondary transfer roller 36 forms a secondary transfer nip by sandwiching the intermediate transfer belt 30 between the secondary transfer roller 36 and the secondary transfer backup roller 32. In addition, similarly to the primary transfer roller 31, a power source is connected to the secondary transfer roller 36, and at least one of a predetermined DC voltage (DC) and an AC voltage (AC) is applied to the secondary transfer roller 36. It is supposed to be.

  The belt cleaning device 35 has a cleaning brush and a cleaning blade arranged so as to contact the intermediate transfer belt 30. The waste toner transfer hose extending from the belt cleaning device 35 is connected to the entrance of the waste toner container.

  A bottle accommodating section is provided at an upper portion of the printer main body, and four toner bottles 2Y, 2M, 2C, and 2K accommodating toner for replenishment are detachably mounted on the bottle accommodating section. A replenishment path is provided between each of the toner bottles 2Y, 2M, 2C, 2K and each of the developing devices 7, and from each of the toner bottles 2Y, 2M, 2C, 2K to each of the developing devices 7 via this replenishment path. The toner is supplied.

  On the other hand, a paper feed tray 10 containing paper P as a recording medium, a paper feed roller 11 for carrying out the paper P from the paper feed tray 10, and the like are provided at a lower portion of the printer main body. Here, the recording medium includes, in addition to plain paper, thick paper, postcards, envelopes, thin paper, coated paper (such as coated paper and art paper), tracing paper, OHP sheets, and the like. Further, a manual paper feed mechanism may be provided.

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

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

The basic operation of the image forming apparatus having the above configuration is as follows.
When the image forming operation is started, each of the photoconductors 5 in each of the image forming units 4Y, 4M, 4C, and 4K is driven to rotate clockwise in the figure by a driving device, and the surface of each of the photoconductors 5 is charged by the charging device 6. It is uniformly charged to a predetermined polarity.

  The charged surface of each 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 monochromatic image information obtained by decomposing a desired full-color image into yellow, magenta, cyan, and black color information. By supplying toner to the electrostatic latent images formed on the respective photoconductors 5 by the respective developing devices 7, the electrostatic latent images are visualized (visualized) as toner images. .

  When the image forming operation is started, the secondary transfer backup roller 32 is driven to rotate in a counterclockwise direction in the drawing, and the intermediate transfer belt 30 is caused to travel around in the direction indicated by the arrow in the drawing. Then, to each of the primary transfer rollers 31, a constant voltage having a polarity opposite to the charging polarity of the toner or a voltage controlled at a constant current is applied. 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 the toner image of each color on the photoconductor 5 reaches the primary transfer nip with the rotation of each photoconductor 5, the toner image on each photoconductor 5 is transferred by the transfer electric field formed in the primary transfer nip. Are sequentially superimposed and transferred onto the intermediate transfer belt 30. In this manner, a full-color toner image is carried on the surface of the intermediate transfer belt 30.

  Further, the toner on each photoconductor 5 that has not been transferred to the intermediate transfer belt 30 is removed by the cleaning device 8. Thereafter, the surface of each photoconductor 5 is neutralized by the neutralization device, and the surface potential is initialized.

  In the lower part of the image forming apparatus, the paper feed roller 11 starts rotating and driving, and the paper P is sent out from the paper feed tray 10 to the transport path R. The sheet P sent to the transport path R is sent to a secondary transfer nip between the secondary transfer roller 36 and the secondary transfer backup roller 32 at a timing by the registration roller 12. 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 transfer electric field formed in the secondary transfer nip causes the toner image on the intermediate transfer belt 30 to move. The toner images are collectively transferred onto the paper P. At this time, the residual toner on the intermediate transfer belt 30 that has not been completely transferred to the paper P is removed by the belt cleaning device 35, and the removed toner is conveyed to the waste toner container and collected.

  Thereafter, the sheet P is transported to the fixing device 20, and the toner image on the sheet P is fixed on the sheet P by the fixing device 20. Then, the paper P is discharged out of the apparatus by the paper discharge rollers 13 and stocked on the paper discharge tray 14.

  The above description is an image forming operation for forming a full-color image on the sheet P. However, a single-color image is formed using any one of the four image forming units 4Y, 4M, 4C, and 4K. It is also possible to form a two-color or three-color image using two or three image forming units.

Next, the configuration of the fixing device 20 according to the present embodiment will be described with reference to FIG. FIG. 2 is a sectional view of the fixing device 20 according to the present embodiment.
The fixing device 20 includes a fixing belt 21 as a fixing member having a hollow endless movable body inside, and a pressing roller as a pressing member including a counter rotating member rotatably provided facing the fixing belt 21. 22.

  Inside the fixing belt 21, a halogen heater 23 as a heat source for heating the fixing belt 21 and a nip forming member 24 forming a nip portion N with a pressure roller 22 facing the fixing belt 21 are provided. I have. Further, inside the fixing belt 21, there is provided a reflection member 26 that reflects light emitted from the halogen heater 23 to the fixing belt 21. The halogen heater 23 is fixedly supported on a side plate of the fixing device 20.

  Further, a temperature sensor 27 is disposed as opposed to the front surface of the fixing belt 21 and serves as a temperature detecting unit for detecting the temperature of the fixing belt 21. Further, a separation plate 28 as a recording medium separating unit for separating the sheet P from the fixing belt 21 and a pressing unit for pressing the pressing roller 22 against the fixing belt 21 are also provided.

  As the fixing belt 21, a thin and flexible endless belt member (including a film) is used. The fixing belt 21 has a base material on the inner peripheral side formed of a metal material such as nickel or stainless steel or a resin material such as polyimide (PI). Further, a release layer on the outer peripheral side formed of a tetrafluoroethylene-perfluoroalkylvinyl ether copolymer (PFA) or polytetrafluoroethylene (PTFE) is provided. Further, an elastic layer made of a rubber material such as silicone rubber may be interposed between the base material and the release layer.

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

  The pressure roller 22 is in contact with the nip forming member 24 via the fixing belt 21 by being pressed toward the fixing belt 21 by a spring or the like as a pressing unit. At a place where the pressure roller 22 and the fixing belt 21 are in pressure contact with each other, the elastic layer 22b of the pressure roller 22 is crushed to form a nip portion N having a predetermined width.

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

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

  Further, when the elastic layer 22b is not provided, the heat capacity is reduced, and the fixability is improved. However, when the unfixed toner is crushed and fixed, minute irregularities on the belt surface may be transferred to the image, and uneven gloss may occur in a solid portion of the image. In order to improve this, it is desirable to provide an elastic layer having a thickness of 100 [μm] or more. By providing an elastic layer having a thickness of 100 [μm] or more, minute unevenness can be absorbed by elastic deformation of the elastic layer, so that it is possible to avoid uneven gloss.

  The elastic layer 22b may be made of solid rubber, but if there is no heat source inside the pressure roller 22, sponge rubber may be used. Sponge rubber is more preferable because the heat insulating property is enhanced and the heat of the fixing belt 21 is hardly deprived. Further, the fixing belt 21 and the pressure roller 22 are not limited to the case where they are in pressure contact with each other, but may be configured to simply contact without applying pressure.

  In the fixing device 20 shown in FIG. 2, the fixing belt 21 is directly heated by radiant heat (heater light) from the halogen heater 23, and the halogen heater 23 as a heat source is provided inside the fixing belt 21.

  The halogen heater 23 is configured to be supplied with power from a power supply serving as a power supply unit provided in the main body of the image forming apparatus 1, output controlled, and generate heat.

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

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

  The nip forming member 24 is disposed longitudinally in the axial direction of the fixing belt 21 or the axial direction of the pressure roller 22, and is fixed and supported by a stay 25. This prevents the nip forming member 24 from being bent by the pressure of the pressure roller 22, so that a uniform nip width can be obtained in the axial direction of the pressure roller 22. The stay 25 is preferably formed of a metal material having high mechanical strength, such as stainless steel or iron, in order to satisfy the function of preventing the nip forming member 24 from bending. However, the stay 25 may be made of resin. It is. The stay 25 is fixedly supported on a side plate of the fixing device 20.

  The reflection member 26 is provided between the stay 25 and the halogen heater 23. In the present embodiment, the reflection member 26 is fixed to the stay 25. Further, since the reflecting member 26 is directly heated by the halogen heater 23, it is desirable that the reflecting member 26 be formed of a high melting point metal material or the like. By arranging the reflecting member 26 in this manner, light emitted from the halogen heater 23 to the stay 25 side is reflected to the fixing belt 21. Accordingly, the amount of light irradiated on the fixing belt 21 can be increased, and the fixing belt 21 can be efficiently heated. In addition, since radiant heat from the halogen heater 23 can be suppressed from being transmitted to the stay 25 and the like, energy can be saved.

  Further, instead of providing the reflecting member 26 as in the present embodiment, the surface of the stay 25 on the side of the halogen heater 23 may be subjected to mirror finishing such as polishing or painting to form a reflecting surface. Further, it is desirable that the reflectivity of the reflection surface of the reflection member 26 or the stay 25 be 90% or more.

  However, since the shape and material of the stay 25 cannot be freely selected in order to secure its strength, it is better to separately provide the reflecting member 26 as in the present embodiment, because the weight of the selection of the shape and material is increased, The member 26 and the stay 25 can be specialized for each function. Further, by providing the reflection member 26 between the halogen heater 23 and the stay 25, the position of the reflection member 26 with respect to the halogen heater 23 becomes closer, so that the fixing belt 21 can be efficiently heated.

  Further, in order to further improve the heating efficiency of the fixing belt 21 due to the reflection of light, it is necessary to consider the direction of the reflecting surface of the reflecting member 26 or the stay 25. If the reflecting surface is arranged concentrically around the halogen heater 23, the light is reflected toward the halogen heater 23, and the heating efficiency is reduced accordingly. On the other hand, if a part or all of the reflecting surface is arranged in a direction that reflects light toward the fixing belt in a direction other than the halogen heater 23, the amount of light reflected in the direction of the halogen heater 23 decreases. In addition, the heating efficiency by the reflected light can be improved.

  Further, in the fixing device 20 according to the present embodiment, various constitutional devices are devised for further energy saving and improvement of the first print time. More specifically, the fixing belt 21 can be directly heated by the halogen heater 23 in a portion other than the nip portion N (direct heating method). In the present embodiment, nothing is interposed between the halogen heater 23 and the left part of the fixing belt 21 in FIG. 2, and radiant heat from the halogen heater 23 is directly applied to the fixing belt 21 in that part.

  Further, in order to reduce the heat capacity of the fixing belt 21, the fixing belt 21 is made thinner and smaller in diameter. Specifically, the thickness of each of the base material, the elastic layer, and the release layer constituting the fixing belt 21 is set in the range of 20 to 50 μm, 100 to 300 μm, and 10 to 50 μm, and the total thickness is set. It is set to 1 mm or less. The diameter of the fixing belt 21 is set to 20 to 40 mm. In order to further reduce the heat capacity, the thickness of the entire fixing belt 21 is desirably 0.2 mm or less, and more desirably 0.16 mm or less. Further, the diameter of the fixing belt 21 is desirably 30 mm or less.

  In the present embodiment, the diameter of the pressure roller 22 is set to 20 to 40 mm, and the diameter of the fixing belt 21 is made equal to the diameter of the pressure roller 22. However, it is not limited to this configuration. For example, the fixing belt 21 may be formed so that the diameter thereof is smaller than the diameter of the pressure roller 22. In this case, since the curvature of the fixing belt 21 at the nip N is smaller than the curvature of the pressure roller 22, the recording medium discharged from the nip N is easily separated from the fixing belt 21.

  The nip forming member 24 is formed of a heat-resistant member having a heat-resistant temperature of 200 ° C. or higher. This prevents the deformation of the nip forming member 24 due to heat in the toner fixing temperature range, secures a stable state of the nip portion N, and stabilizes the output image quality. The nip forming member 24 includes a general material such as polyether sulfone (PES), polyphenylene sulfide (PPS), liquid crystal polymer (LCP), polyether nitrile (PEN), polyamide imide (PAI), polyether ether ketone (PEEK), and the like. It is possible to use a suitable heat-resistant resin. In this embodiment, TI-8000 manufactured by Toray Industries, which is an LPC, is used.

  A heat equalizing member 41 is provided between the nip forming member 24 and the fixing belt, and the heat equalizing member 41 is made of a good heat conductive material such as a metal.

FIG. 3 is a diagram showing a temperature distribution in the width direction of the fixing belt 21 of the conventional example without the heat equalizing member 41 and a temperature distribution in the width direction of the fixing belt 21 of the present embodiment with the heat equalizing member 41. is there.
A chain line A in FIG. 3 shows the temperature distribution of the fixing belt 21 of the conventional example, and a solid line B shows the temperature distribution of the fixing belt 21 of the present embodiment. W in FIG. 3 indicates the width of a sheet passing through the fixing nip N.

  In the conventional example, the heat given to the fixing belt 21 from the halogen heater 23 is mainly applied to the paper, toner, and heat in the area of the paper passing width W (hereinafter, referred to as a paper passing section) at the nip portion N to contact the outside of the fixing belt. The power is transmitted to the pressure roller and the nip forming member 24 that contacts the inside of the fixing belt. On the other hand, in a region outside the sheet passing width (hereinafter, referred to as a non-sheet passing portion), heat given to the fixing belt 21 is transmitted only to the nip forming member 24. Since the nip forming member 24 is generally made of a resin having a low thermal conductivity, the amount of heat transferred to the nip forming member 24 is small, and heat transfer is difficult. As a result, the heat accumulates in the fixing belt 21 as the sheet continuously passes in the non-sheet passing portion, and the temperature of the non-sheet passing portion becomes higher than the temperature of the sheet passing portion as shown by a chain line A in FIG. Become. In particular, when the fixing belt 21 and the pressure roller diameter, the linear velocity, and the productivity are fixed, as the non-sheet passing portion is larger, the heat accumulated in the fixing belt 21 increases, and the end portion temperature increases.

  On the other hand, in the present embodiment, since the heat equalizing member 41 having a high thermal conductivity is provided, heat excessively accumulated in the non-sheet passing portion of the fixing belt 21 is absorbed by the heat equalizing member 41. The absorbed heat is deprived of heat by the paper passing, and moves to a relatively low-temperature central paper passing portion or a non-heating portion of the halogen heater. As a result, as shown by the solid line B in FIG. 3, the rise in the temperature of the non-sheet passing portion of the fixing belt 21 could be suppressed. As shown in FIG. 3, when the heat equalizing member 41 was provided, the temperature of the non-sheet passing portion could be reduced by 5 to 10 ° C. as compared with the case where the heat equalizing member 41 was not provided.

  It is also possible to configure the nip forming member 24 with a member having good thermal conductivity to enhance the capability of suppressing the end portion temperature rise. However, in this case, the heat of the fixing belt 21 is conducted from the nip forming member to the metal stay 25, and is conducted from the stay 25 to the side plate of the fixing belt, whereby the temperature of the nip forming member 24 decreases quickly. The heat of the fixing belt 21 is excessively removed. As a result, a drop in temperature occurs in the paper passing portion. Further, since heat is excessively absorbed, it takes time for the fixing belt 21 to reach the fixing temperature, which adversely affects the warm-up time and the power consumption. Therefore, by providing the nip forming member 24 as a member having poor heat conductivity and providing the heat equalizing member 41 made of a member having good heat conductivity, heat transfer to the stay 25 can be suppressed, and the nip forming member 24 can be suppressed. Can suppress excessive absorption of the heat of the fixing belt, and can equalize the temperature of the fixing belt in the width direction.

  Further, it is desirable to use a metal member such as copper as the heat equalizing member 41, but it is also possible to use a resin member in accordance with the magnitude of the temperature rise in the non-sheet passing portion.

  Further, a sliding sheet 29 as a lubricant-impregnated member impregnated with a lubricant is provided between the heat equalizing member 41 and the fixing belt 21. The sliding sheet 29 is made of a sheet in which fine fluorine fibers having heat resistance are woven or a porous resin having heat resistance, and absorbs the lubricant by capillary action.

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

  In the present embodiment, since the inner peripheral surface of the fixing belt and the nip forming member 24 are configured to be in pressure contact with each other, if the friction between the inner peripheral surface of the fixing belt and the nip forming member surface is large, the traveling of the fixing belt 21 is increased. And causes poor fixing, paper wrinkles, and the like. Further, the life of the fixing device is shortened due to an increase in the torque due to the large friction. Therefore, as described above, the sliding sheet 29 impregnated with the lubricant is provided, the lubricant is applied from the sliding sheet 29 to the inner peripheral surface of the belt, and the nip forming member 24 and the inner peripheral surface of the fixing belt are rotated by the lubricant. It reduces friction with the surface. As a result, the fixing belt 21 can travel smoothly.

FIG. 4 is a diagram illustrating the adhesion of the lubricant impregnated in the sliding sheet 29 to the inner peripheral surface of the fixing belt 21.
As shown in FIG. 4, in the present embodiment, the sliding sheet 29 is longer than the length of the nip portion in the paper passing direction, and is provided so as to wrap around the nip forming member 24 and the heat equalizing member 41. .
When the sliding sheet 29 is pressed by the pressure roller 22 via the fixing belt 21, the lubricant impregnated in the sliding sheet 29 is squeezed out as shown by an arrow in the figure to fix the fixing belt. 21 adheres to the inner peripheral surface. Thereby, the frictional resistance between the inner peripheral surface of the fixing belt 21 and the nip forming member 24 can be reduced.

FIG. 5 is a perspective view showing a flange 42 as a belt holding member for holding the fixing belt, and the fixing belt 21.
Guide portions 42a provided on the flange 42 are inserted into both ends in the width direction of the fixing belt 21, and the fixing belt 21 is rotatably held by the guide portions 42a. The guide portion 42a has a substantially cylindrical shape with the pressure roller side cut out. The guide portion 42 a has an outer diameter substantially equal to the inner diameter of the fixing belt 21, and has a length that enters a predetermined amount inside from both ends of the fixing belt 21.

  As shown in FIG. 5, since the guide portion 42 a has a substantially cylindrical shape in which the pressure roller side is cut out, the member does not contact both ends in the longitudinal direction of the sliding sheet 29. Open. In order to maintain the lubricating effect of the lubricant over time, it is desired that the sliding sheet 29 hold as much lubricant as possible. However, if the sliding sheet 29 holds a large amount of lubricant, the lubricant may leak from both ends in the longitudinal direction when the sliding sheet 29 is pressed by the pressure roller 22. The lubricant leaked from both ends in the longitudinal direction of the sliding sheet adheres to the fixing belt 21 outside the longitudinal ends of the sliding sheet. Then, during the repetition of the fixing process, the lubricant moves to the end in the width direction of the fixing belt, and the lubricant leaks from between the fixing belt 21 and the guide portion 42a. As a result, the lubricant impregnated in the sliding sheet 29 gradually decreases with use over time, and eventually becomes exhausted. Therefore, even if a large amount of lubricant is held in the sliding sheet 29, the effect of the lubricant cannot be maintained over time. Thus, in the present embodiment, the lubricant is prevented from leaking out from both ends in the longitudinal direction of the sliding sheet 29, and the effect of the lubricant can be maintained over time. This will be described below with reference to the drawings.

FIG. 6 is a diagram illustrating a characteristic portion of the present embodiment.
As shown in FIG. 6, in the present embodiment, a lubricant supply member 43 for impregnating a lubricant is provided between the heat equalizing member 41 and the nip forming member 24. It has a hole 41a such as a communication hole for allowing the lubricant to move between the sliding sheet 29 and the sliding sheet 29. The lubricant supply member 43 is made of a material having a higher lubricant retaining force than the sliding sheet. The holding force of the lubricant supply member 43 can be represented by an amount by which the lubricant is impregnated. Further, the lubricant supply member 43 is made of a material that allows the lubricant to leak into the hole 41a when pressure is applied while absorbing a lubricant such as a sponge.

  The hole 41 a is formed in the entire heat equalizing member 41 in the longitudinal direction. The size and the like of the hole 41a may be appropriately set according to the amount of lubricant supplied from the lubricant supply member 43 to the sliding sheet.

  The sliding sheet 29 has a minimum amount of lubricant that can reduce the friction between the nip forming member 24 and the inner peripheral surface of the fixing belt by the lubricant. The moving sheet 29 holds the moving sheet. On the other hand, the lubricant supply member 43 holds more lubricant than the sliding sheet 29.

  In the present embodiment, the lubricant held by the lubricant supply member 43 leaks into the hole 41a due to the pressing force of the pressure roller, and is stored in the hole 41a. When the lubricant in the sliding sheet 29 decreases, the lubricant stored in the hole 41 a of the heat equalizing member 41 is supplied to the sliding sheet 29. Accordingly, even if a large amount of lubricant is not held in the sliding sheet 29, the effect of the lubricant can be maintained over time, and the fixing belt can be smoothly rotated over time. The sliding sheet 29 has a minimum amount of lubricant that can reduce the friction between the nip forming member 24 and the inner peripheral surface of the fixing belt by the lubricant. May be held on the sliding sheet 29. Therefore, when the sliding sheet 29 is pressed by the pressure roller 22, the lubricant impregnated in the sliding sheet 29 can be prevented from leaking from the longitudinal end of the sliding sheet 29.

  Furthermore, when the sliding sheet 29 is pressed by the pressure roller 22, the lubricant impregnated in the sliding sheet 29 can leak out to the hole 41a, and the lubricant leaked to the hole 41a Can be absorbed by the lubricant supply member 43. Thereby, the leakage of the lubricant from both ends in the longitudinal direction of the sliding sheet 29 can be further suppressed.

  Further, the lubricant holding force of the lubricant supply member 43 is set higher than that of the sliding sheet 29. Thus, the lubricant supply member 43 can hold a large amount of lubricant. In addition, since the holding power of the lubricant is high, even when holding more lubricant than the sliding sheet, it is possible to prevent the lubricant impregnated in the lubricant holding member from leaking from the longitudinal end. Can be. By making the lubricant holding force of the sliding sheet 29 lower than that of the lubricant supply member 43, the lubricant easily leaks out, and the lubricant can be satisfactorily adhered to the inner peripheral surface of the fixing belt 21.

  In addition, a heat equalizing member 41 as a lubricant non-absorbing member having low lubricant absorptivity is disposed between the lubricant supplying member 43 and the sliding sheet 29, and the lubricant is supplied from the hole 41 a of the heat equalizing member 41. It was configured to supply. Thus, it is possible to suppress the supply of a large amount of lubricant from the lubricant supply member 43 to the sliding sheet 29. Further, the supply of the lubricant from the lubricant supply member 43 to the sliding sheet 29 can be easily controlled by the size, shape, arrangement, and the like of the holes 41a.

  Further, it is preferable to appropriately set the size, shape, arrangement, and the like of the holes 41a in consideration of the characteristics of the lubricant such as the viscosity of the lubricant.

  Next, a modified example will be described.

[Modification 1]
FIG. 7 is a diagram illustrating the first modification. FIG. 7A is an exploded perspective view of a main part, and FIG. 7B is a schematic cross-sectional view of a portion A in FIG. 7A. As shown in FIG. The thickness of the lubricant supply member at the center in the longitudinal direction is thicker than at the ends. The surface of the nip forming member 24 on the side of the lubricant supply member is a concave surface in which the center side is recessed in accordance with the thickness of the lubricant supply member.

  As described above, by increasing the thickness of the central portion in the longitudinal direction of the lubricant supply member 43, it is possible to hold more lubricant than the end portions in the longitudinal direction. Thereby, the amount of lubricant supplied to the sliding sheet from the longitudinal central portion of the lubricant supply member 43 through the hole 41a of the heat equalizing member 41 can be made larger than that at both ends. As a result, it is possible to prevent a large amount of lubricant from being retained on the longitudinal end side of the sliding sheet, and it is possible to suppress leakage of the lubricant from both longitudinal ends of the sliding sheet. .

[Modification 2]
FIG. 8 is a diagram illustrating a second modification.
In the second modification, the hole 41a of the heat equalizing member 41 is arranged on the downstream side in the sheet passing direction.
The lubricant in the sliding sheet moves from the upstream side to the downstream side in the moving direction of the fixing belt in the nip portion as the fixing belt 21 moves. Therefore, by arranging the hole 41a of the heat equalizing member 41 on the upstream side in the moving direction of the fixing belt in the nip portion, the lubricant supplied from the lubricant supplying member 43 to the sliding sheet 29 is applied to the surface of the fixing belt. As the fixing belt moves, it moves downstream in the moving direction of the fixing belt, and the lubricant can be evenly supplied to the sliding sheet 29.

[Modification 3]
FIG. 9 is a diagram illustrating a third modification.
In the third modification, the opening area of the hole 41a at the center in the longitudinal direction of the heat equalizing member 41 is larger than the opening area of the end. Specifically, the hole 41a has a convex shape that is convex toward the upstream side in the paper passing direction. As described above, by increasing the opening area at the center in the longitudinal direction, the lubricant is supplied to the sliding sheet mainly at the center in the longitudinal direction. Can be prevented from retaining a large amount of lubricant. Therefore, leakage of the lubricant from both ends in the longitudinal direction of the sliding sheet 29 can be suppressed.
The opening area on the end side and the opening area on the center of the hole 41a may be appropriately determined based on the characteristics of the lubricant such as viscosity and the amount of the lubricant that the sliding sheet 29 is desired to hold at the end.

[Modification 4]
FIG. 10 is a diagram illustrating a fourth modification.
In the fourth modification, the hole 41 a is provided only at the center in the longitudinal direction of the heat equalizing member 41. Thus, the lubricant is supplied to the sliding sheet 29 only from the central portion in the longitudinal direction. Thereby, it is possible to further suppress the retention of a large amount of lubricant on the longitudinal end side of the sliding sheet 29, and to prevent the lubricant from leaking from both longitudinal ends of the sliding sheet 29. It can be further suppressed. The lubricant supplied to the central portion in the longitudinal direction of the sliding sheet 29 moves toward the longitudinal end due to the capillary phenomenon and the pressing force of the pressure roller 22. Therefore, even in the configuration in which the hole 41 a is provided only in the longitudinal center portion of the heat equalizing member 41, the necessary minimum amount of lubricant can be held also in the vicinity of the longitudinal end of the sliding sheet 29.

  The length and size of the hole 41a of the heat equalizing member 41 may be appropriately determined based on the characteristics of the lubricant such as viscosity and the amount of the lubricant to be held on the sliding sheet 29a.

What has been described above is merely an example, and each embodiment has a specific effect.
(Aspect 1)
A rotatable endless fixing belt 21, a nip forming member 24 disposed on the inner peripheral side of the fixing belt 21, and a nip disposed to face the nip forming member 24 with the fixing belt 21 interposed therebetween. A pressing member such as a pressing roller 22 for pressing the fixing belt 21 toward the nip forming member so that a nip portion is formed by sandwiching the forming member 24 and the fixing belt 21, the fixing belt 21 and the nip forming member 24, a lubricant impregnating member such as a sliding sheet 29 for impregnating a lubricant between the lubricant impregnating member and the nip forming member 24. A lubricant holding member such as a lubricant supply member 43 having a high lubricant holding force was provided.
According to this, between the lubricant impregnated member such as the sliding sheet 29 and the nip forming member 24, a lubricant holding member such as the lubricant supply member 43 having a higher holding force of the lubricant than the lubricant impregnated member. By providing the lubricant, a large amount of lubricant can be held in the lubricant holding member without holding a large amount of lubricant in the lubricant containing member. This makes it possible to reduce the amount of lubricant contained in the lubricant-containing member as compared with the related art, and to suppress leakage of the lubricant from both ends of the lubricant-impregnated member in the width direction of the fixing belt. Further, the lubricant holding member has a high holding force of the lubricant, and even if a large amount of the lubricant is held, the lubricant hardly leaks from the end of the lubricant holding member in the width direction of the fixing belt. Accordingly, it is possible to suppress the lubricant from leaking from both ends in the belt width direction of the lubricant holding member.
Further, when the amount of the lubricant contained in the lubricant impregnated member decreases, the lubricant held in the lubricant holding member is supplied to the lubricant containing member, and the lubricant impregnated with the lubricant impregnated member over time. A lubricant can be interposed between the belt and the belt. Thus, the fixing belt can be smoothly rotated.

(Aspect 2)
In (Aspect 1), the lubricant of the lubricant holding member is disposed between the lubricant holding member such as the lubricant supply member 43 and the lubricant impregnated member such as the sliding sheet 29, and is supplied to the lubricant impregnated member. And a non-lubricant non-absorbing member such as a heat equalizing member 41 having a lower absorptivity of the lubricant than the lubricant impregnated member.
According to this, as described in the embodiment, by supplying the lubricant of the lubricant holding member to the lubricant impregnated member from the communication hole such as the hole 41a provided in the lubricant non-absorbing member, The amount of lubricant supplied from the lubricant holding member to the lubricant impregnated member can be easily controlled by the size, shape, arrangement, and the like of the communication holes. This can prevent a large amount of lubricant from being supplied to the lubricant impregnated member, and the lubricant leaks from the end of the lubricant impregnated member due to the pressing force of the pressure member such as the pressure roller. Can be suppressed. Further, the lubricant can be leaked from the lubricant holding member or the lubricant impregnated member to the hole 41a by the pressing force of the pressing member. Accordingly, it is possible to suppress the lubricant from leaking from the widthwise end of the fixing belt of the lubricant holding member or the lubricant impregnated member.

(Aspect 3)
In (Aspect 2), the lubricant non-absorbing member is a heat equalizing member for equalizing the temperature in the width direction of the fixing belt.
According to this, as described with reference to FIG. 3, it is possible to suppress a rise in the widthwise end temperature of the fixing belt 21. In addition, the number of components can be reduced and the apparatus can be inexpensive as compared with a configuration in which a heat equalizing member is provided separately from the lubricant non-absorbing member.

(Aspect 4)
In (Aspect 3), the heat equalizing member 41 extends over the entire non-sheet passing area when the recording material having the minimum size that can pass through the apparatus passes through the nip portion.
According to this, it is possible to suppress a rise in the temperature of the non-sheet passing area of the fixing belt when the recording material having the minimum size that can pass through the apparatus passes.

(Aspect 5)
In any of (Aspect 2) to (Aspect 4), the communication hole such as the hole 41a is provided on the nip portion on the upstream side in the moving direction of the fixing belt.
According to this, as described in Modification 2, the lubricant held by the lubricant holding member such as the lubricant supply member 43 is provided upstream of the lubricant impregnated member such as the sliding sheet 29 in the moving direction. Supplied. The lubricant in the lubricant impregnated member moves from the upstream side to the downstream side in the moving direction as the surface of the fixing belt moves. Therefore, the lubricant supplied on the upstream side in the moving direction of the lubricant impregnated member such as the sliding sheet 29 can be evenly distributed to the sliding sheet 29.

(Aspect 6)
In any one of (Aspect 2) to (Aspect 5), the communication hole has a convex shape in which a central portion in the width direction of the fixing belt protrudes further downstream than the both ends in the moving direction of the fixing belt.
According to this, as described in the third modification, the opening at the width direction end of the fixing belt can be made smaller than the center portion, and the lubrication supplied to the width direction end of the lubricant impregnated member can be reduced. The volume can be less than in the center. As a result, it is possible to prevent a large amount of lubricant from being retained on the longitudinal end side of the sliding sheet, and it is possible to suppress leakage of the lubricant from both longitudinal ends of the sliding sheet. . In addition, by increasing the opening at the center, a predetermined amount of lubricant can be supplied to the lubricant-containing member.

(Aspect 7)
In each of (Aspect 2) to (Aspect 6), the communication hole such as the hole 41a is provided only in the central portion in the fixing belt width direction of the lubricant non-absorbing member such as the heat equalizing member 41.
According to this, as described in the fourth modification, the lubricant is supplied to the lubricant impregnated member only from the center in the width direction of the fixing belt. Thereby, it is possible to suppress that a large amount of lubricant is retained on the width direction end side of the lubricant impregnated member, and the lubricant leaks from the width direction end portion of the lubricant impregnated member. Can be further suppressed.

(Aspect 8)
In any one of (Embodiment 1) to (Embodiment 7), the thickness of the lubricant holding member such as the lubricant supply member 43 at the center in the fixing belt width direction is thicker than at both ends.
According to this, as described in the second modification, the amount of the lubricant held at the center of the lubricant holding member in the width direction of the fixing belt can be made larger than that at the end. Thereby, the amount of lubrication supplied to the central portion in the width direction of the lubricant impregnated member can be made larger than that of the end portion. As a result, it is possible to prevent a large amount of lubricant from being retained on the longitudinal end side of the sliding sheet, and it is possible to suppress leakage of the lubricant from both longitudinal ends of the sliding sheet. .

(Aspect 9)
An image carrier such as a photoreceptor 5; toner image forming means for forming a toner image on the image carrier (in this embodiment, a charging device 6, an exposure device 9 and a developing device 7); Transfer means such as a transfer device 3 for transferring the image from the image carrier onto a recording material such as paper P; and fixing means such as a fixing device 20 for fixing the toner image transferred on the recording material to the recording material. In the provided image forming apparatus, the fixing device according to any one of (Aspect 1) to (Aspect 8) is used as a fixing unit.
According to this, it is possible to suppress the occurrence of defects such as fixing failure and paper wrinkling over time.

1: Image forming device 3: Transfer device 5: Photoreceptor 6: Charging device 7: Developing device 9: Exposure device 20: Fixing device 21: Fixing belt 22: Pressure roller 23: Halogen heater 24: Nip forming member 25: Stay 26: reflective member 27: temperature sensor 28: separating plate 29: sliding sheet 41: heat equalizing member 41a: hole 42: flange 42a guide 43: oil supply member

JP 2014-178520 A

Claims (7)

A rotatable endless fixing belt,
A nip forming member disposed on the inner peripheral side of the fixing belt,
The fixing belt is disposed so as to face the nip forming member with the fixing belt interposed therebetween, and the fixing belt is formed so that a nip portion is formed by sandwiching the fixing belt with the nip forming member. A pressure member for pressing the side,
A fixing device including a lubricant impregnated member for impregnating a lubricant between the fixing belt and the nip forming member,
The lubricant-impregnated member,
Between the nip forming member, a lubricant holding member having a higher holding force of the lubricant than the lubricant impregnated member ,
It has a communication hole arranged between the lubricant holding member and the lubricant impregnated member, for supplying the lubricant of the lubricant holding member to the lubricant impregnated member, A lubricant non-absorbing member having low lubricant absorbency,
The fixing device, wherein the lubricant non-absorbing member is a heat equalizing member for equalizing a temperature in a width direction of the fixing belt . The fixing device according to 請 Motomeko 1,
The fixing device is characterized in that the heat equalizing member extends over the entire non-sheet passing area when a recording material of a minimum size that can be passed by the apparatus passes through the nip portion. The fixing device according to claim 1, wherein
The fixing device according to claim 1, wherein the communication hole is provided in the nip portion on an upstream side in a moving direction of the fixing belt. The fixing device according to claim 1 , wherein
The fixing device according to claim 1, wherein the communication hole has a convex shape in which a central portion in a width direction of the fixing belt protrudes downstream in a moving direction of the fixing belt from both ends. The fixing device according to claim 1 , wherein
The fixing device according to claim 1, wherein the communication hole is provided only at a central portion of the lubricant non-absorbing member in a width direction of the fixing belt. The fixing device according to any one of claims 1 to 5,
A fixing device, wherein a thickness of a center portion of the lubricant holding member in a width direction of the fixing belt is thicker than both end portions. An image carrier;
A toner image forming means for forming a toner image on an image carrier,
Transfer means for transferring the toner image from the image carrier to a recording material,
A fixing unit for fixing the toner image transferred onto the recording material to the recording material,
As the fixing means, an image forming apparatus which comprises using a fixing device according to any one of claims 1 to 6.

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