JP4681966B2 - Image fixing device - Google Patents

Description

  The present invention relates to an image fixing apparatus suitable for use as an image heating fixing apparatus (hereinafter abbreviated as a fixing apparatus) mounted on an electrophotographic or electrostatic recording type image forming apparatus.

  For example, in an image forming apparatus such as an electrophotographic copying machine or printer, film heating is used as one of fixing devices (fixing devices) that heat and fix an unfixed toner image formed on a sheet-like recording medium as a permanently fixed image. System devices are known (Patent Documents 1 to 4).

  This film heating type fixing device includes a flexible fixing film (hereinafter abbreviated as a film), a heating body for heating the film, a heating body and a fixing nip portion (hereinafter abbreviated as a nip portion) across the film. And a pressure roller for forming the same. The recording material on which the unfixed toner image is formed and held is nipped and conveyed at the nip portion, and heat and pressure are applied to the unfixed toner image during the conveyance process to fix the unfixed toner image to the recording material. is there.

  According to this film heating type fixing device, an on-demand type device is configured by using a ceramic heater (hereinafter abbreviated as a heater) as a heating element and a heat-resistant resin film or metal film having a low heat capacity as a film. I can do it. That is, only when the image forming apparatus performs image formation, the heater as a heat source is energized so that the film is heated to a predetermined fixing temperature (target temperature). Therefore, there are advantages such as a short waiting time from the power-on of the image forming apparatus to an image forming executable state (quick start property) and a significant reduction in power consumption during standby (power saving).

  In Patent Document 5, a protrusion is provided at a position where a pressure roller and a nip portion are formed via a film in a support member that supports the film. In other words, by creating a locally high pressure area in the nip, even when the process speed during the fixing process is increased, a good fixed image can be obtained with high gloss (glossiness). Has been.

Patent Document 6 discloses a technique for reducing the sliding resistance of the film against the heating body by interposing a lubricant such as grease between the heating body and the surface of the film that contacts the heating body. ing.
JP-A-63-313182 Japanese Patent Laid-Open No. 2-157878 JP-A-4-44075 JP-A-4-204980 JP-A-10-198200 JP-A-5-27619

  By the way, the toner layer for forming the unfixed toner image includes many voids. When heat fixing is performed in a state where the toner layer includes voids, the air existing in the voids of the toner layer is heated and expanded at the same time as the toner is melted. When this air enters between the toner and the recording material, the fixing property is deteriorated, and when the expanded air breaks through the toner layer and escapes outside, a minute hole reaching from the image surface to the recording material is formed. Many are formed. These holes are macroscopically observed as bubbles, and the smoothness of the image surface is reduced and the gloss is reduced, and the uniformity of the image surface is reduced depending on the presence or absence of bubbles in the same plane.

  In a conventional heat roller type fixing device that fixes an unfixed toner image by heating and pressurization, if an elastic layer is provided on the surface of the fixing roller, the gloss of the image surface and the uniformity of the image surface are reduced. Can be avoided. This is because the elastic layer on the surface of the fixing roller deforms following the unevenness of the surface of the unfixed toner image in the nip, and the uneven toner layer is uniformly heated and melted, and the fixing is performed while the bubbles are squeezed out by the stress of the elastic layer. Because it is done.

  However, in the case of a film heating type fixing device that fixes an unfixed toner image with a film having no elastic layer or a thin elastic layer, the gloss of the image surface and the uniformity of the image surface tend to decrease. is there. This is because the film does not follow the unevenness of the toner layer, so that uniform heating and melting cannot be performed, and the foaming effect does not occur.

  Therefore, as shown in FIGS. 14 and 15, a protrusion 32b (hereinafter referred to as a pressure protrusion) is provided on a holder 32 that supports the film 31 so as to be movable, and recording is performed via the film at the pressure protrusion. The toner image T on the material is pressed to squeeze out bubbles from the toner layer. This makes it possible to ensure good fixability with high gloss.

  However, when the pressing protrusion 32b as described above is provided on the holder 32, the grease G adhering to the inner surface of the film during the rotational movement of the film 31 is scraped off by the pressing protrusion. When the grease G is scraped off, the circulation of the grease due to the rotational movement of the film 31 is deteriorated, and the sliding resistance reduction effect by the grease cannot be sufficiently exhibited. For this reason, the film easily slips during the rotational movement, which causes image disturbance.

  Further, since the sliding resistance reduction effect due to the grease cannot be sufficiently exhibited, the driving torque when the film 31 is rotationally driven via the pressure roller 20 becomes large.

  Further, a part of the grease G scraped off by the pressurizing protrusion 32b is likely to be collected and accumulated between the heater 33 and the pressurizing protrusion 32b in the nip portion during the rotational movement of the film 31. Most of the grease G accumulated between the heater 33 and the pressurizing protrusion 32b does not move even when the film 31 rotates and stays agglomerated and stays as it is. The stagnant grease G not only contributes to the reduction of the sliding resistance of the film 31, but also contributes to image unevenness such as grease streaks in the toner image.

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide an image fixing device capable of improving image unevenness while improving the fixability of a toner image .

Another object of the present invention is to provide an image fixing device capable of reducing the sliding resistance of the fixing film while improving the fixing property of the toner image .

Another object of the present invention is to provide an image fixing device capable of reducing the driving torque of the fixing film while improving the fixing property of the toner image .

In order to achieve the above object, the image fixing device according to the present invention includes a heater, a support member that supports the heater, and an endless belt-like fixing film that rotates while an inner surface is in contact with the heater and the support member. And a pressure roller that forms a fixing nip portion together with the heater and the support member via the fixing film, and a lubricant is applied to the inner surface of the fixing film, and the fixing of the support member The pressure roller is located at a nip portion forming portion downstream of the heater in the fixing film rotation direction more than the contact surface of the heater with the fixing film in a direction orthogonal to the fixing film rotation direction. and projecting portions are provided which project to the side, heat fixing a toner image on a recording material while nipping and conveying the recording material bearing the toner image in the fixing nip portion That the image fixing apparatus, said the protruding portion, the lubrication is scraped off by contact penetrates across the fixing film rotation direction upstream side of the projecting portion to the fixing film rotation direction downstream the fixing film and the projecting portion through holes for agent to pass through, characterized in that a plurality are provided at predetermined intervals in a direction perpendicular to the fixing fill beam rotation direction.

According to the image fixing apparatus of the present invention, the through hole is provided with a plurality on the projecting portion of the support member, lubricant scraped off by contact with the inner surface or et protrusion of the fixing film again over the protruding portion fixing It returns to the inner surface of the film and circulates with the rotation of the fixing film. Thereby, the stagnation of the lubricant can be improved. Therefore, it is possible to improve image unevenness while improving the fixability of the toner image .

Further, according to the image fixing device of the present invention , since the stagnation of the lubricant can be improved as described above, the effect of reducing the sliding resistance between the fixing film and the protruding portion by the lubricant can be exhibited. Therefore, the sliding resistance of the fixing film can be reduced while improving the fixing property of the toner image. Further, the driving torque of the fixing film can be reduced while improving the fixing property of the toner image.

Hereinafter, the present invention will be described in detail with reference to the drawings.
[ Example 1 ]

(1) Example of Image Forming Apparatus FIG. 1 is a schematic configuration diagram of an example of an image forming apparatus in which the image fixing apparatus of the present invention can be mounted as an image heat fixing apparatus. The image forming apparatus of this example is a tandem color LBP (color laser beam printer) using an electrophotographic process.

  Y, M, C, and Bk are first to fourth image forming stations for forming toner images of respective colors of yellow component, magenta component, cyan component, and black component, respectively. They are arranged in parallel in order.

  The first to fourth image forming stations Y, M, C, and Bk respectively include drum-type electrophotographic photosensitive members (hereinafter referred to as photosensitive drums) 1a, 1b, 1c, and 1d, and primary charging means. 2a, 2b, 2c, and 2d. Further, it has laser beam exposure means (hereinafter referred to as a scanner) 3a, 3b, 3c, 3d, developing sections 4a, 4b, 4c, 4d, cleaning means 6a, 6b, 6c, 6d, and the like.

  Reference numeral 9a denotes an endless electrostatic adsorption conveyance belt (hereinafter abbreviated as a conveyance belt) as a carrying member for a recording material (recording material) S. The conveyor belt 9a is arranged in the longitudinal direction across the image forming stations on the photosensitive drum side (printer front side) of the first to fourth image forming stations Y, M, C, and Bk. . Reference numerals 9b, 9c, 9d, and 9e are a driving roller, two fixed rollers, and a tension roller, respectively, in which the conveying belt 9a is suspended and stretched. The conveyor belt 9a is rotationally driven by a driving roller 9b at a peripheral speed corresponding to the rotational peripheral speed of the photosensitive drum 1 in the direction indicated by the arrow (clockwise) in the drawing.

  Reference numerals 5a, 5b, 5c, and 5d denote first to fourth transfer rollers, which are in pressure contact with the photosensitive drums 1a to 1d of the image forming stations Y, M, C, and Bk, respectively, via the conveyance belt 9a. Yes.

  In the image forming stations Y, M, C, and Bk, the photosensitive drums 1a to 1d are rotationally driven in a direction indicated by an arrow (counterclockwise) at a predetermined process speed. These photosensitive drums are rotationally driven by a drum motor (DC servo motor) (not shown), but an independent drive source may be provided for each photosensitive drum. The rotational drive of the drum motor is controlled by a DSP (digital signal processor) (not shown), and other controls are performed by a CPU (not shown).

  The photosensitive drums 1a to 1d are uniformly charged to a predetermined polarity and potential by the primary charging means 2a to 2d during the rotation process, and optical image exposure is performed on the charged surfaces by the scanners 3a to 3d. Then, an electrostatic latent image corresponding to the image information is formed on each photosensitive drum. The electrostatic latent image is developed as a toner image by the developing units 4a to 4d, so that the color separation component images of the full-color image are respectively formed on the surfaces of the photosensitive drums 1a to 1d by an electrophotographic process. A black toner image is formed.

  On the other hand, the recording material (transfer sheet) S in the feeding cassette 8a disposed below the image forming apparatus main body is separated and fed one by one by the sheet feeding roller 8b at a predetermined sequence control timing. Then, the recording material S is synchronized by a registration roller 8c that stops and re-transports the recording material S, and is fed to the transport belt 9a from below. The recording material S is electrostatically attracted and held on the surface of the transport belt 9a, and is transported upward by the rotation of the transport belt. During the transport process, the toner images of yellow, magenta, cyan, and black formed on the surfaces of the photosensitive drums 1a to 1d at the transfer portions of the image forming stations Y, M, C, and Bk are sequentially transferred in sequence. To receive. As a result, an unfixed full-color toner image is synthesized and formed on the surface of the recording material S.

  Further, in each of the image forming stations Y, M, C, and Bk, the photosensitive drums 1a to 1d after the toner image transfer to the recording material S are removed by the cleaning means 6a to 6d to remove the remaining deposits such as the transfer residual toner. Repeatedly used for image formation.

  The recording material S that has been subjected to the superimposed transfer of the toner image from each of the photosensitive drums 1a to 1d and is conveyed to the upper end of the conveying belt 9a is separated from the surface of the conveying belt 9a at the drive roller 9b, and is fixed to the fixing device (fixing device). 10 is sent. After the toner image is heated and fixed in the fixing device 10, the toner image is discharged onto the discharge tray 13 by the discharge roller 10 c.

  The above is the operation of the apparatus in the single-sided printing mode. In the double-sided printing mode, the recording material is conveyed by the discharge roller 10c until the rear end of the recording material S passes through the discharge double-side guide 10d. After that, the recording material S is guided to the double-side conveyance path by reversing the discharge roller 10c. Specifically, the rear end of the recording material S is conveyed along the upper surface of the discharge duplex guide 10d by the reverse rotation of the discharge roller 10c. The recording material S is further conveyed along guide ribs 11 a provided at the lower part of the ventilation duct 11 and guide guides 12 a provided at the lower part of the operation panel 12, and sent to the double-sided roller 14. Further, the recording material S passes through the double-sided rollers 15 and 16 on the downstream side, and is conveyed along the U-turn guide 17 and is synchronized by the registration roller 8c, so that the transfer nip portion between the photosensitive drums 1a to 1d and the conveying belt 9a. Will be sent again. Subsequent operations are the same as those in the single-sided printing mode.

(2) Fixing device 10
FIG. 2 is an enlarged schematic cross-sectional view of the main part of the fixing device 10. The fixing device 10 is a heating device of a film heating method and a pressure roller driving method (tensionless type) using a cylindrical (endless belt-shaped) fixing film as a flexible member.

  Reference numeral 30 denotes a heating unit that constitutes a heating rotator, and 20 denotes an elastic pressure roller (hereinafter abbreviated as a pressure roller) as a pressure rotator. N is abbreviated as a nip portion.

2-1) Pressure roller 20
The pressure roller 20 is formed of a core bar 21 made of aluminum or iron, an elastic layer 22 on the outside thereof, and a release layer 23 that covers the surface of the elastic layer 22. Both ends of the cored bar 21 are fixedly disposed by being rotatably supported by bearings between unillustrated device side plates. The pressure roller 20 is rotationally driven at a predetermined speed in the direction of arrow A (clockwise) by the rotational drive system M.

  The elastic layer 22 is a solid rubber layer formed of silicon rubber or the like, or a sponge rubber layer formed by foaming silicon rubber to have a heat insulating effect. Or it is a foam rubber layer etc. which disperse | distributed the hollow filler in the silicon rubber layer, gave the bubble part in hardened | cured material, and improved the heat insulation effect.

  The release layer 23 is made of a fluorine-based resin such as perfluoroalkoxy resin (PFA), polytetrafluoroethylene resin (PTFE), tetrafluoroethylene-hexafluoropropylene resin (FEP). Alternatively, GLS latex (trademark of Daikin Industries, Ltd.) coating may be applied. The releasable layer 23 may be a tube coated or a surface coated with a paint.

2-2) Heating unit 30
The heating unit 30 includes a support holder (hereinafter abbreviated as a holder) 32 as a support member. The holder 32 is a horizontally long member having a longitudinal direction in the width direction (perpendicular to the drawing) perpendicular to the transport direction SF of the recording material S. A concave groove portion (heater support portion) 32d is formed in the center portion of the outer surface of the holder 32 on the side of the pressure roller 20 along the longitudinal direction. 33) is fixedly arranged. Further, a metal-made rigid pressure stay (hereinafter abbreviated as a pressure stay) 34 having a U-shaped cross section is provided on the inner surface of the holder 32 opposite to the pressure roller 20 side. The inner surface of the holder 32 is held by a pressure stay 34. A sleeve-like fixing film (hereinafter abbreviated as a film) 31 as a flexible member is loosely fitted over the assembly of the holder 32, the heater 33, and the pressure stay 34. Accordingly, the holder 32 rotatably supports the film 31 on the outer surface side, and supports the heater 33 by the recessed groove portion 32d at the center portion on the outer surface side. Fluorine grease (see FIG. 4) G is interposed as a lubricant between the heater 33 and the inner peripheral surface of the film 31 in contact with the surface of the heater.

  In the fixing device 10 of this embodiment, the heating unit 30 is placed on the left side of FIG. 2 of the pressure roller 20 in which both ends of the cored bar 21 are rotatably supported and held between the device side plates, and the heater 33 side is placed. They are arranged in parallel with the pressure roller 20 toward the pressure roller 20. Then, both end portions of the pressure stay 34 are pressed against the elasticity of the elastic layer 22 of the pressure roller 20 with a predetermined pressure F in the direction of the pressure roller by a pressing means such as a spring (not shown). As a result, the heater 33 and the holder 32 are allowed to enter the elastic layer 22 of the pressure roller through the film 31 on the left side of the pressure roller 20 to form the nip portion N.

  When the pressure roller 20 is rotationally driven in the direction indicated by arrow A, the rotational force generated by the rotational driving of the pressure roller acts on the film 31. With this rotational force, the film 31 is driven to rotate in the direction indicated by the arrow B (counterclockwise) while the inner peripheral surface of the film 31 slides in close contact with the outer surfaces of the holder 32 and the heater 33 at the nip portion N. At this time, since the sliding resistance with respect to the holder 32 and the heater 33 is reduced by the grease G applied to the inner peripheral surface of the film (the inner surface of the fixing film), the film 31 is smoothly driven and rotated as the pressure roller 20 is driven to rotate. To do.

  The pressure roller 20 is rotationally driven, so that the film 31 is in a driven rotation state, the heater 33 is energized, and the heater is heated to a predetermined fixing temperature (target temperature). In this temperature control state, a recording material S carrying an unfixed toner image (toner image) T is introduced between the film 31 in the nip portion N and the pressure roller 20. Then, the toner image carrying surface side of the recording material S is in close contact with the outer peripheral surface of the film 31 at the nip portion N, and the nip portion is nipped and conveyed together with the film. In this nipping and conveying process, the heat of the heater 33 is applied to the recording material S via the film 31, and the unfixed toner image T on the recording material is heated and pressurized on the surface of the recording material and melted and fixed. The The recording material S coming out of the nip portion N is separated from the film 31 and the pressure roller 30.

  The film 31 is a resin film having a base layer of polyimide, polyamideimide, PEEK, PES, PPS, PFA, PTFE, FEP or the like having heat resistance and heat insulation. The surface layer is coated with a heat-resistant resin having good releasability such as PFA, PTFE, FEP, silicone resin, or a single coating.

  The holder 32 is made of a heat resistant resin such as liquid crystal polymer, phenolic resin, PPS, PEEK, etc., and a slidable resin.

2-3) Heater 33
FIG. 3 is an explanatory diagram of the configuration of the heater 33 in this embodiment. The heater 33 is a surface heating type ceramic heater having a low heat capacity.

  The heater 33 includes the following members i) to iv).

  i) A ceramic substrate (insulating substrate (hereinafter abbreviated as “substrate”)) a made of highly insulating ceramics such as horizontally long alumina, aluminum nitride, silicon carbide and the like whose longitudinal direction is the width direction of the recording material S.

ii) For example, Ag / Pd (silver palladium: silver alloy), RuO ₂ , Ta ₂ N formed on the surface side of the substrate a by linear printing or by strip printing by screen printing or the like along the length. Current-carrying heating element (heating resistor) b.

  iii) Electrode portions c and c formed of Ag / Pt (silver / platinum) or the like, which are electrically connected to both ends in the longitudinal direction of the energization heating element b.

  iv) An insulating protective layer d, such as a thin glass coat or a fluororesin coat, which is provided on the surface of the energization heating element b and is electrically insulated and can withstand sliding against the film 31.

  In the heater 33, a temperature detection element TH such as a thermistor as temperature detection means is provided on one side in the longitudinal direction of the substrate a. In addition, a thermal fuse H is provided as a safety element at approximately the center in the longitudinal direction on the back side of the ceramic substrate a. The temperature detection element TH and the temperature fuse H are both disposed in the region of the energization heating element b. Electric power is supplied from the energization control circuit 101 to the electrode portions c and c. The energization control circuit 101 supplies power to the electrode portions c and c in accordance with the heater activation signal output from the control circuit 100 as the control means. As a result, the heater 33 is rapidly and rapidly heated by the heat generated by the energization heating element b.

  The temperature detection element TH detects the temperature rise of the heater 33 and outputs a detected temperature signal (resistance value) to the control circuit 100. In the control circuit 100, the heater 33 is temperature-controlled by ON / OFF control of the energization control circuit 101 so that the film 31 reaches a predetermined fixing temperature based on the detected temperature signal from the temperature detecting element TH.

  The thermal fuse H is connected in series to the energization control circuit 101 and one electrode part c. The heater 33 is activated when the temperature rises abnormally beyond the fixing temperature, and the power supply from the energization control circuit 101 to the electrode portion c is stopped.

2-4) Measures for Improving Fixability of Toner Image T FIG. 4 is an enlarged detail view near the nip portion N shown in FIG. FIG. 5 is a perspective view of the holder 32 as seen from the outer surface side. In the apparatus of FIG. 2, the nip portion N faces upward, but in FIG. 4, for convenience of explanation, the nip portion N is drawn sideways. Although the film 31 and the pressure roller 20 are in contact with each other at the nip portion N, the film and the pressure roller are illustrated separately in FIG. 4 for convenience of explanation.

  As shown in FIG. 4, in order to improve the fixability of the toner image on the recording material S, a pressing protrusion 32 b is provided on the holder 32 in the nip N. The pressing protrusion 32b is provided on the downstream side of the heater 33 in the rotation direction (movement direction) A of the film 31 and close to the heater, and protrudes beyond the surface of the heater to the pressing roller 20 side. . Therefore, the toner image T on the recording material S after being heated by the heater 33 in the nip portion N can be pressed through the film 31 by the pressing protrusion 32b. That is, the fixing nip portion forming portion of the holder 32 and the portion downstream of the heater in the rotation direction of the fixing film is applied more than the contact surface of the heater with the fixing film in the direction orthogonal to the rotation direction of the fixing film. A projecting portion 32b projecting to the pressure roller side is provided. As a result, the toner image can be fixed while squeezing bubbles from the toner layer of the toner image T on the recording material S, and good fixability can be ensured with high gloss.

2-5) Measures for Improving Image Unevenness, Measures for Reduction of Film 31 Slip and Driving Torque The holder 32 has a through hole 35a through which the grease G escapes downstream of the pressure protrusion 32b in the transport direction SF of the recording material S Is provided (FIG. 5). A plurality of through holes 35 a are provided at uniform pitch intervals in the longitudinal direction of the holder 32. These through holes 35a can be formed by drilling holes in the holder 32 with a drilling machine or the like.

  Further, the holder 32 has a leveling protrusion 32a on the upstream side (recording material introduction side) of the nip portion N in the rotation direction A of the film 31, and on the downstream side of the nip portion N (recording material discharge side). Separation protrusions 32c are provided. The leveling protrusion 32 a is formed along the length of the holder 32, and its tip is in contact with the inner peripheral surface of the film 31. The separation protrusion 32c is also formed along the length of the holder 32. The tip of the separation protrusion 32c is brought into contact with the inner peripheral surface of the film 31, and a curvature portion smaller than the curvature of the rotation trajectory of the film is formed on the film. The separation protrusion 32c separates the toner image carrying surface of the recording material S from the outer peripheral surface of the film at the curvature portion formed on the film 31 (curvature separation).

  Each of the plurality of through holes 35a has a grease introduction port 35a1 in the nip portion N on the upstream side in the conveyance direction of the recording material S of the pressing protrusion 32b. Each of the plurality of through holes 35a has a grease discharge port 35a2 on the downstream side in the conveyance direction of the recording material. In the present embodiment, the grease introduction port 35a1 is formed to communicate with a gap provided between the pressurizing protrusion 32b and the heater 33. Further, the grease discharge port 35a2 is formed so as to communicate with a concave space K provided between the pressurizing protrusion 32b and the separation protrusion 32c. That is, the plurality of through holes 35a are provided so as to connect the heater support portion of the holder 32 and the downstream side in the fixing film rotation direction with respect to the protruding portion 32b. The pitch interval L between adjacent through holes in the plurality of through holes 35a is set to the following dimensions, for example. The holder 32 is formed with holes 37 and 38 for separately accommodating the temperature detecting element TH and the temperature fuse H (FIG. 3) provided on the back side of the heater 33. In order to avoid these holes, adjacent through holes are formed. The pitch interval L of 35a is set to 25 mm.

  As shown in FIG. 4, the leveling protrusion 32 a is a tip portion that is in contact with the inner peripheral surface of the film 31 on the upstream side of the nip portion N, and the grease G applied to the inner peripheral surface of the film is applied to the film. During the rotation of 31, the grease thickness is made constant in the width direction of the recording material S.

  When the film 31 whose grease thickness is fixed by the leveling protrusion 32a further rotates and passes through the heater 33 and reaches the pressure protrusion 32b, the grease G on the inner peripheral surface of the film becomes the tip of the pressure protrusion 32b. It is evenly stretched in the longitudinal direction of the holder while being shaved. At this time, most of the grease G is scraped off from the inner peripheral surface of the film, but a part of the grease G extended in the longitudinal direction of the holder reduces the sliding resistance between the pressing protrusion 32b and the inner peripheral surface of the film. Contribute.

  The grease G shaved from the inner peripheral surface of the film accumulates in the gap between the heater 33 and the pressurizing protrusion 32b as the film 31 rotates. The grease G collected in the gap portion is pushed by the grease accumulated in the gap portion with the subsequent rotation of the film 31 and enters the grease introduction port 35a1, and is discharged into the concave space K from the grease discharge port 35a2. Is done. That is, the grease G scraped from the inner peripheral surface of the film by the pressurizing protrusion 32b during the rotational movement of the film 31 can be released to the concave space K by the rotational movement of the film.

  The grease G discharged into the concave space K is blocked by the separation protrusion 32c that is in contact with the inner peripheral surface of the film, and an appropriate amount is discharged from the concave space by the rotational movement of the film 31.

  The grease G discharged from the concave space K reaches the leveling protrusion 32 a by the rotational movement of the film 31.

  As described above, most of the grease G adhering to the inner peripheral surface of the film passes through the leveling protrusion 32a, the heater 33, the through hole 35a, and the separation protrusion 32c in this order by the rotational movement of the film 31. Will circulate. That is, the lubricant scraped from the inner surface of the fixing film 31 by contact with the protruding portion 32b of the holder 32 returns to the inner surface of the fixing film again after the contact position (position of the protruding portion 32b) and circulates with the rotation of the fixing film. Will be.

  In the present embodiment, when the through hole 35a is formed in the holder 32, the through hole may be formed in the holder by configuring the holder with two members and integrating them. FIG. 6 is an enlarged detail view of the vicinity of the nip portion of the fixing device having a holder constituted by two members.

  The holder 32 includes a first member 32A that supports the heater 33, and a second member 32B that has a pressure protrusion 32b. In the first member 32A and the second member 32B, a plurality of grooves constituting the through hole 35a are formed in advance on the mutual bonding surfaces, and the grooves face the bonding surfaces of the first member and the second member. The two members are integrated with each other by welding or adhesive. Thereby, the through hole 35a can be formed in the joint surface of the first member 32A and the second member 32B. Thus, by configuring the holder 32 with two members or two or more members, it is possible to form a through hole having a more complicated shape or a through hole having a more desired diameter in the holder.

  In the fixing device 10 according to the present exemplary embodiment, the fixing property of the toner image T can be improved by the pressing protrusion 32 b provided in the holder 32. Further, the grease G scraped by the pressurizing protrusion 32b can be released into the concave space K by the plurality of through holes 35a provided in the holder 32, and the grease does not stagnate in the gap.

Therefore, occurrence of image unevenness such as grease streaks on the toner image T on the recording material S can be reduced. Further, since the grease G does not stay in the gap, the sliding resistance reduction effect by the grease can be sufficiently exerted, and the sliding resistance between the film 31 and the heater 33 and between the film 31 and the holder 32 can be reduced. Moreover, the drive torque at the time of rotationally driving the film 31 can also be reduced.
[ Example 2 ]

  In this embodiment, another example of the through hole provided in the holder of the fixing device will be described.

  FIG. 7 is an enlarged detail view in the vicinity of the nip portion of the fixing device according to the present embodiment. In the present embodiment, the same members and portions as those of the fixing device of the first embodiment are denoted by the same reference numerals, and the description thereof is omitted. The same applies to Examples 3 to 5 described later.

  The holder 32 is provided with a through-hole 35b through which the grease G escapes on the downstream side of the pressure projecting portion 32b in the conveyance direction SF of the recording material S. A plurality of through holes 35 b are provided at predetermined pitch intervals in the longitudinal direction of the holder 32.

  Each of the plurality of through holes 35b has a grease introduction port 35b1 in the nip portion N on the upstream side in the conveyance direction of the recording material S of the pressing protrusion 32b. Each of the plurality of through holes 35b has a grease discharge port 35b2 on the downstream side of the nip portion N in the conveyance direction SF of the recording material S. In this embodiment, the grease introduction port 35 b 1 is formed so as to communicate with the gap between the pressurizing protrusion 32 b and the heater 33. Further, the grease discharge port 35a2 is formed so as to communicate with a gap between the holder 32 and the film 31 on the downstream side of the separation protrusion 32c in the transport direction SF of the recording material S.

  As shown in FIG. 7, most of the grease G scraped off from the inner peripheral surface of the film by the pressurizing protrusion 32b accumulates in the gap between the heater 33 and the pressurizing protrusion 32b as the film 31 rotates. . The grease G collected in the gap portion is pushed by the grease accumulated in the gap portion with the subsequent rotational movement of the film 31, thereby entering the grease introduction port 35b1 and discharged from the grease discharge port 35b2 to the gap portion. . That is, the grease G scraped from the inner peripheral surface of the film by the pressurizing protrusion 32b during the rotational movement of the film 31 can be released to the gap by the rotational movement of the film, and the grease does not stagnate in the gap.

  Therefore, also in the present embodiment, the same effect as that of the first embodiment can be obtained. In the present embodiment, most of the grease G is released to the gap, so that the grease can be circulated more efficiently than in the first embodiment.

  Also in the present embodiment, when the through hole 35b is formed in the holder 32, the through hole may be formed in the holder by configuring the holder with two members and integrating them. FIG. 8 is an enlarged detail view of the vicinity of the nip portion of a fixing device having a holder constituted by two members.

The holder 32 includes a first member 32C that supports the heater 33, and a second member 32D that includes a pressure protrusion 32b and a separation protrusion 32c. In the first member 32C and the second member 32D, a plurality of grooves constituting the through holes 35b are formed in advance on the mutual bonding surfaces, and the grooves face the bonding surfaces of the first member and the second member. The two members are integrated with each other by welding or adhesive. Thereby, the through hole 35b can be formed in the joint surface between the first member 32C and the second member 32D.
[Reference Example 1]

In this reference example , another example of the through hole provided in the holder of the fixing device will be described.

FIG. 9 is an enlarged detail view near the nip portion of the fixing device according to this reference example .

  The holder 32 is provided with a through hole 35c that guides the grease G from the upstream side of the nip portion N to the pressure protrusion 32b in the conveyance direction SF of the recording material S. A plurality of through holes 35 c are provided at predetermined pitch intervals in the longitudinal direction of the holder 32.

Each of the plurality of through holes 35c has a grease introduction port 35c1 on the upstream side of the nip portion N in the conveyance direction SF of the recording material S. Each of the plurality of through holes 35c has a grease discharge port 35c2 in the nip portion N on the upstream side in the conveyance direction SF of the recording material S of the pressure projecting portion 32b. In this reference example , the grease introduction port 35c1 is formed so as to be opened on the film inner peripheral surface side between the leveling protrusion 32a and the heater 33 in the transport direction SF of the recording material S. Further, the grease discharge port 35c2 is formed so as to communicate with the gap between the pressurizing protrusion 32b and the heater 33. That is, the plurality of through holes 35 c are provided so as to straddle the heater 33 from the upstream side of the heater 33 to the downstream side of the heater 33 in the rotation direction of the fixing film 31.

  As shown in FIG. 9, when the film 31 with the grease thickness made constant by the leveling protrusion 32a further rotates and reaches the grease introduction port 35c1, a gap between the holder 32 and the film 31 is formed at the peripheral edge of the grease introduction port. Grease G stagnates and enters the grease inlet. The grease G that has entered the grease introduction port 35c1 is guided by the grease that enters the grease introduction port with the subsequent rotational movement of the film 31, thereby being guided from the grease discharge port 35c2 to the pressurizing protrusion 32b through the gap. Grease G is constantly supplied to the pressure protrusion 32b by the movement of the film 31, and the grease is uniformly extended in the longitudinal direction of the holder by the pressure protrusion and sent into the concave space K. Grease does not stagnate.

Therefore, also in this reference example , the same effect as that of the first embodiment can be obtained.

In this reference example , when the through hole 35c is formed in the holder 32, a groove as a through hole is formed by cutting the bottom surface of the concave groove portion 32d of the holder and the side surface of the leveling protrusion portion 32a with a machine tool. Thus, a through hole can be formed in the holder (FIG. 10).
[Reference Example 2]

In this reference example , another example of the through hole provided in the holder of the fixing device will be described.

FIG. 11 is an enlarged detail view near the nip portion of the fixing device according to this reference example .

  The holder 32 is provided with a through-hole 35d that guides the grease G from the upstream side of the nip portion N to the pressure protrusion 32b in the conveyance direction SF of the recording material S. A plurality of through holes 35 d are provided at predetermined pitch intervals in the longitudinal direction of the holder 32.

Each of the plurality of through holes 35d has a grease introduction port 35d1 on the upstream side of the nip portion N in the conveyance direction SF of the recording material S. Each of the plurality of through holes 35d has a grease discharge port 35d2 in the nip portion N on the upstream side in the conveyance direction SF of the recording material S of the pressure projecting portion 32b. In this reference example , the grease introduction port 35d1 is formed in communication with the gap between the holder 32 and the film 31 on the upstream side of the leveling protrusion 32a in the transport direction SF of the recording material S. Further, the grease discharge port 35d2 is formed so as to communicate with the gap between the pressurizing protrusion 32b and the heater 33. That is, the plurality of through holes 35 d are provided so as to straddle the heater 33 from the upstream side of the heater 33 to the downstream side of the heater 33 in the rotation direction of the fixing film 31, as in the third embodiment.

  As shown in FIG. 11, when the grease thickness is made constant during the rotational movement of the film 31 by the leveling protrusion 32a, the grease G stagnating between the holder 32 and the film 31 in the vicinity of the leveling protrusion is formed. The grease enters the grease inlet 35d1. The grease G that has entered the grease introduction port 35d1 is guided by the grease that enters the grease introduction port with the subsequent rotational movement of the film 31, thereby being guided from the grease discharge port 35d2 to the pressure projecting portion 32b through the gap portion. Grease G is constantly supplied to the pressure protrusion 32b by the movement of the film 31, and the grease is uniformly extended in the longitudinal direction of the holder by the pressure protrusion and sent into the concave space K. Grease does not stagnate.

Therefore, also in this reference example , the same effect as that of the first embodiment can be obtained.

Also in this reference example , when the through hole 35d is formed in the holder 32, the through hole may be formed in the holder by configuring the holder with two members and integrating them. FIG. 12 is an enlarged detail view of the vicinity of the nip portion of the fixing device having a holder constituted by two members.

The holder 32 includes a first member 32E that supports the heater 33, and a second member 32F having a leveling protrusion 32a. In the first member 32E, a groove is formed by cutting with a machine tool as a through-hole along the bottom surface of the recessed groove portion 32d. Then, the joining surface of the second member 32F is brought into contact with the joining surface of the first member 32E in which the groove is formed, and both members are integrated by welding or an adhesive. As a result, a through hole 35d can be formed in the joint surface between the first member 32E and the second member 32F.
[Example 3]

Oite in Examples 1 and 2, the through hole of the holder 32 may have different shapes of the grease inlet and grease discharge port. FIG. 13 is an explanatory diagram of an example in which the shapes of the grease introduction port 35a1 and the grease discharge port 35a2 are changed in the through hole 35a of the holder 32 of the first embodiment.

  In the through hole 35a, the grease discharge port 35a2 is formed so as to expand toward the recording material S conveyance direction. As a result, the grease G can be circulated more uniformly.

[Others]
In are provided a plurality, pitch transmural throughbore 35a~35d uniform pitch 25mm through holes 35a along the (width direction of the recording material S) longitudinally in the holder 32 in the embodiment 1, the nip portion N However, the present invention is not limited to this and may be shorter. By shortening the pitch interval of the through holes 35a to 35d, it is possible to efficiently circulate even if grease having high viscosity is used as the lubricant. Further, the pitch interval L between the through holes 35a to 35d may be a non-uniform pitch interval. Moreover, the cross-sectional shape of the through holes 35a to 35d is not limited to a round shape, but may be a square shape or a triangular shape.

Schematic configuration diagram of an example of an image forming apparatus Enlarged cross-sectional model view of the main part of the fixing device of Example 1 Structure explanatory drawing of the heater of Example 1 FIG. 4 is an enlarged detail view near the nip portion N of the fixing device according to the first exemplary embodiment. The perspective view of the holder of Example 1 FIG. 3 is an enlarged detail view near the nip portion of the fixing device according to the first exemplary embodiment. FIG. 4 is an enlarged detail view near the nip portion of the fixing device according to the second exemplary embodiment. FIG. 4 is an enlarged detail view near the nip portion of the fixing device according to the second exemplary embodiment. Detailed enlarged view near the nip portion of the fixing device of Reference Example 1 . Detailed enlarged view near the nip portion of the fixing device of Reference Example 1 . Detailed enlarged view near the nip portion of the fixing device of Reference Example 2 Detailed enlarged view near the nip portion of the fixing device of Reference Example 2 Explanatory views of another holder over Expanded cross-sectional model view of the main parts of a conventional fixing device Detailed enlarged view near the nip of a conventional fixing device

10... Image fixing device, 20... Pressure roller, 30.
31... Fixing film, 32... Support holder, 32 b.
33... Heater, 35a, 35b, 35c, 35d ... through hole,
G ... Grease (lubricant), S ... Recording material, T ... Toner image,
SF... Recording material conveyance direction, K... Concave space, N.
L ・ ・ ・ ・ Pitch between through holes

Claims (1)

A heater, a support member that supports the heater, an endless belt-shaped fixing film whose inner surface rotates while contacting the heater and the support member, and a fixing nip portion together with the heater and the support member via the fixing film A pressure roller for forming the fixing film, and a lubricant is applied to an inner surface of the fixing film, and a fixing nip portion forming portion of the support member and a portion downstream of the heater in the fixing film rotation direction Is provided with a protrusion that protrudes toward the pressure roller from the contact surface of the heater with the fixing film in a direction orthogonal to the rotation direction of the fixing film. an image fixing apparatus for heat-fixing onto the recording material the toner image while the recording material is pinched and conveyed for bearing a toner image, wherein the projecting portion includes a fixing of the projecting portion Irumu through holes for the lubricant to pass through the rotating direction from the upstream side across the fixing film downstream side in the rotational direction through the scraped off by the contact of the protruding portion and the fixing film, the fixing fill beam Rotation Direction A plurality of image fixing devices are provided at predetermined intervals in a direction perpendicular to the image.

Images