JP2008275963A - Image heating device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an image heating device which does not impede the rotation of a flexible member and is capable of obtaining a sufficient cleaning effect. <P>SOLUTION: The image heating device which heats an image on a recording medium P, while nipping and conveying the recording material, in a nip portion N3 and cleans the surface of the flexible member 1a by a cleaning member 5 has a backup member 6 which comes into contact with the inner surface of the flexible member, so as to hold the cleaning member and the flexible member. The backup member 6 has a plurality of rotating bodies 6a divided in the longitudinal direction orthogonal to the recording material conveying direction of the flexible member and the plurality of rotating bodies are rotated in contact with the inner surface of the flexible member, respectively. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to an image heating apparatus suitable for use as a fixing device mounted on an image forming apparatus such as an electrophotographic copying machine or an electrophotographic printer. In particular,

  As an image heating device (fixing device) mounted on an electrophotographic printer or copying machine, a ceramic heater, a sleeve-like flexible member that moves while in contact with the heater, and the heater and nip portion via the flexible member There are some which have a pressure roller for forming the. Patent Documents 1 and 2 describe this type of fixing device. The recording material carrying the unfixed toner image is heated while being nipped and conveyed by the nip portion of the fixing device, whereby the image on the recording material is heated and fixed on the recording material. This fixing device has an advantage that the time required for starting energization of the heater and raising the temperature to the fixing possible temperature is short. Therefore, a printer equipped with this fixing device can shorten the time (FPOT: first printout time) from the input of a print command to the output of an image on one sheet. In addition, this type of fixing device has an advantage that power consumption during standby waiting for a print command is small.

  A printer equipped with the above fixing device can form a glossy image on an inexpensive recording material (for example, plain paper) by heat-fixing the image on the recording material in a fixing device. It is possible to form images.

  However, in the above-described printer, it is difficult to form an image up to the end of a recording material that has been put to practical use in an ink jet printer (hereinafter referred to as full-surface image formation). It is an obstacle.

  One factor that makes it difficult to form an image on the entire surface is contamination of the flexible member (film) in the fixing device. For normal image formation, the toner image can be evenly pressurized and supplied with heat at the nip, and all the unfixed toner image is fixed to the recording material, and the toner of the toner image remains on the outer peripheral surface (surface) of the film. There is almost nothing. However, in the entire surface image formation, the toner of the toner image may wrap around not only the edge of the recording material but also the side surface in the thickness direction. In that case, pressurization and heat supply may be incomplete, and the toner in that portion may remain on the film surface (offset phenomenon). Since such offset toner circulates and adheres to the recording material as the film rotates, it contaminates the recording material and lowers the image quality.

In the film heating type fixing device as described above, it is effective to provide a means for cleaning the offset toner on the film surface in order to remove the offset toner remaining on the film surface. However, since the film has flexibility, the rotational form of the film is not stable. Therefore, when a web, a cleaning roller, or the like is used as a cleaning member for removing dirt on the film surface, a backup member that supports the film from the inside is provided at a position where the cleaning member contacts the film surface (Patent Document). 3).
JP-A-63-313182 JP-A-44075 Japanese Unexamined Patent Publication No. 2000-315033 (paragraph 0026, FIG. 1)

  In a film heating type fixing device, since it is necessary to reduce the heat capacity of the film, it is difficult to provide a sufficient space inside the film. Therefore, the backup member must be small. In order to obtain a sufficient cleaning effect, the cleaning member needs to be brought into strong contact with the film surface to some extent. In this case, if the backup member rubs strongly against the inner surface of the film, the rotation of the film is hindered and the film slips, and the recording material cannot be conveyed, or the image fixed on the recording material is rubbed. there is a possibility. Therefore, as the backup member, it is preferable to use a small rotating body that does not hinder the rotation of the film, that is, a rotating body having a sufficiently small outer diameter relative to the inner diameter of the film.

  However, when it is intended to make the rotating body small, the shape of the rotating body becomes elongated in the longitudinal direction perpendicular to the recording material conveyance direction. When an elongated rotating body is used, the contact pressure between the rotating body and the film varies in the longitudinal direction of the rotating body, and smooth rotation of the film tends to be difficult.

  In addition, reducing the contact area between the backup member and the inner surface of the film can also reduce film rotation inhibition, but the contact between the cleaning member and the film surface becomes unstable, and the cleaning effect tends to be insufficient. was there.

  An object of the present invention is to provide an image heating apparatus capable of obtaining a sufficient cleaning effect without inhibiting the rotation of a flexible member.

The configuration of the present invention includes a heating body, a sleeve-like flexible member that rotates in contact with the heating body, a pressure member that forms a nip portion by sandwiching the flexible member with the heating body, A cleaning member that contacts the surface of the flexible member at a position other than the nip portion; and a backup member that contacts the inner surface of the flexible member so as to sandwich the cleaning member and the flexible member. An image heating apparatus that heats an image on the recording material while nipping and conveying the recording material at the nip portion and cleans the surface of the flexible member by the cleaning member.
The backup member has a plurality of rotating bodies divided in a longitudinal direction perpendicular to the recording material conveyance direction of the flexible member, and the plurality of rotating bodies rotate in contact with the inner surface of the flexible member, respectively. It is characterized by doing.

  According to the present invention, it is possible to provide an image heating apparatus that can obtain a sufficient cleaning effect without hindering the rotation of the flexible member.

  Hereinafter, the present invention will be described in detail with reference to the drawings.

(1) Image Forming Apparatus FIG. 6 is a structural model diagram showing an example of an image forming apparatus in which the image heating apparatus according to the present invention can be mounted as a fixing device. This image forming apparatus is a full-color laser beam printer of an entire image forming type that forms four color images on a plurality of standard recording materials (for example, paper, an OHP sheet, cloth, etc.) using an electrophotographic system.

  The image forming apparatus 100 shown in this embodiment includes a first image carrier and a second image carrier. The first image carrier is an endless intermediate transfer belt (hereinafter referred to as a transfer belt) 17 as an intermediate transfer member. The second image carrier is a drum-type electrophotographic photosensitive member (hereinafter referred to as a photosensitive drum) 11. The photosensitive drum 11 is rotated in the direction of the arrow.

  A primary charger 12 as a primary charging means, an exposure device 13 as an exposure means, a developing device 14 as a developing means, and a photosensitive drum cleaner (hereinafter referred to as a cleaner) in that order along the rotation direction of the photosensitive drum 11. ) 16 is arranged.

As an example of the transfer belt 17, an endless resin belt having a thickness of about 0.05 mm to 0.3 mm is used, and a volume resistivity of 10 by carbon, ZnO, SnO ₂ , TiO ₂ , and other conductive fillers. it can be used to regulate the resistivity of about ^{7 ~10 11 Ω} · cm. As a material of the resin belt, for example, PVdF (polyvinylidene fluoride), nylon, PET (polyethylene terephthalate), polycarbonate, PI (polyimide), or the like can be used.

The transfer belt 17 is wound around three rollers 17a, 17b, and 17c. A primary transfer roller 15 serving as a primary transfer unit is disposed inside the transfer belt 17 so as to sandwich the photosensitive drum 11 and the transfer belt 17 therebetween. By pressing the outer peripheral surface (front surface) of the transfer belt 17 in contact with the outer peripheral surface (front surface) of the photosensitive drum 11 by the primary transfer roller 15, a nip portion (hereinafter referred to as a primary transfer portion) N1 is formed. Forming. A secondary transfer roller 18 as a secondary transfer unit is disposed outside the transfer belt 17 so as to sandwich the roller 17b and the transfer belt 17 therebetween. A nip portion (hereinafter referred to as a secondary transfer portion) N2 is formed by pressing the outer peripheral surface (front surface) of the roller 18 in contact with the surface of the transfer belt 17 by the secondary transfer roller 18. The primary transfer roller 15 is configured by coating a cored bar with an elastic material having a medium resistance (actual resistance (nip forming method) at a nip forming portion when applying 1 KV is 10 ⁶ to 10 ¹⁰ Ω). The secondary transfer roller 18 is configured by covering the cored bar with an EPDM foam layer having a resistance value of medium resistance.

  The fixing device 10 is disposed at a position downstream of the secondary transfer portion N2 in the conveyance direction of the recording material P.

  In the image forming apparatus 100 of this embodiment, the photosensitive drum 11 rotates at a predetermined process speed (peripheral speed = 100 mm / sec) in the direction of the arrow in the drawing. The surface of the photosensitive drum 11 is uniformly charged by a primary charger 12 to which a voltage is applied from a primary charging bias power source 12E. The exposure device (laser beam scanner) 13 scans the surface of the photosensitive drum 11 with the laser light L modulated in accordance with the image information signal sent from the host computer (external device) in the main scanning direction. The surface of the photosensitive drum 11 is exposed by the laser light L, and an electrostatic latent image (electrostatic image) corresponding to the image information signal is formed on the surface of the photosensitive drum 11. At this time, the intensity of the laser beam L and the irradiation spot diameter are appropriately set according to the resolution of the image forming apparatus 100 and a desired image density. As for the electrostatic latent image on the surface of the photosensitive drum 11, the portion irradiated with the laser light L has a bright portion potential VL (about −100 V), and the portion not irradiated with the laser light has a dark portion potential VD charged by the primary charger 12. It is formed by being held at (about -700V).

  The electrostatic latent image formed on the surface of the photosensitive drum 11 reaches a portion facing the developing device 14 by the rotation of the photosensitive drum 11. The developing device 14 holds developing devices 14a, 14b, 14c, and 14d that store toners (developers) of four colors of yellow, black, magenta, and cyan, respectively, on a rotatable support 14A. Then, the support 14A rotates in the direction of the arrow to move the developing devices 14a, 14b, 14c, and 14d of predetermined colors to a position (developing position) facing the surface of the photosensitive drum 11.

  In this embodiment, the latent image formed on the surface of the photosensitive drum 11 first reaches a portion facing the first color (yellow) developing device 14a disposed at the developing position. The latent image is visualized as a yellow toner image (development image) by supplying toner charged with the same polarity (negative polarity in this embodiment) as the charging polarity of the surface of the photosensitive drum 11 from the developing device 14a. Imaged.

  The toner image formed on the surface of the photosensitive drum 11 is primarily transferred sequentially to the surface of the transfer belt 17 in the primary transfer portion N1. At this time, the primary transfer roller 15 is applied with a primary transfer bias having a reverse polarity to the toner (in this embodiment, +100 to +1000 V) from the primary transfer bias power source 15E, and the toner image on the surface of the photosensitive drum 11 is applied. Is primarily transferred onto the surface of the transfer belt 17. The primary transfer residual toner remaining on the surface of the photosensitive drum 11 is removed by a cleaning unit such as a blade provided in the photosensitive drum cleaner 16 as the photosensitive drum 11 rotates. As a result, the surface of the photosensitive drum 11 is cleaned to prepare for the next image formation.

  After developing the first color (yellow), the second color developer 14b (magenta), the third color developer 14c (cyan), and the fourth color developer 14d (black) in the same order. The toner image is formed on the surface of the photosensitive drum 11. Then, the toner images of the respective colors are primarily transferred onto the surface of the transfer belt 17 while being superimposed on the toner image previously transferred onto the surface of the transfer belt 17, thereby forming a full color image on the surface of the transfer belt 17.

  On the other hand, a recording material P fed one by one from a sheet feeding means (not shown) having a recording material storage cassette, a recording material feeding roller, and the like is conveyed to the secondary transfer portion N2. At this time, a secondary transfer bias having a voltage of a polarity opposite to that of the toner (in this embodiment, + 1K to +6 KV) is applied to the secondary transfer roller 18 from the secondary transfer bias power source 18E. As a result, the toner image is secondarily transferred from the transfer belt 17 onto the recording material P.

  The recording material P that has passed through the secondary transfer portion N2 is conveyed to the fixing device 10. The unfixed toner image in the fixing device 10 is fixed on the recording material P by being heated and pressurized.

  The secondary transfer residual toner exists on the intermediate transfer belt 17 after the toner image is secondarily transferred to the recording material P. In this embodiment, the secondary transfer residual toner is recharged by a charger (not shown), transferred to the photosensitive drum 11, and the intermediate transfer belt 17 is cleaned. The toner transferred to the photosensitive drum 11 is removed and collected by the photosensitive drum cleaner 16.

(2) Fixing Device FIG. 1 is a schematic cross-sectional view of an example of the fixing device 10. FIG. 2 is a front model view of the fixing device 10 of FIG. FIG. 3 is a schematic longitudinal sectional view of the fixing device 10 of FIG. This fixing device is a film heating type fixing device.

  In the following description, with respect to the fixing device 10 and its constituent members, the longitudinal direction is a direction orthogonal to the recording material conveyance direction on the surface of the recording material. The short direction is the recording material conveyance direction on the surface of the recording material.

  A fixing device 10 shown in this embodiment includes a heating unit 1, a pressure roller (pressure member) 3, a cleaning roller (cleaning member) 5, and a backup roller (backup member) 6.

  In the heating unit 1, a sleeve-like fixing film (hereinafter referred to as a film) 1 a is provided around a heat-resistant substantially semicircular saddle-shaped heater holder (holding member) 1 c that holds a ceramic heater (heating body) 2. It is loosely fitted on the loose. The film 1a is obtained by using a PI (polyimide) resin having a thickness of 50 μm as a base material and coating an outer peripheral surface (surface) of the base material with a 10 μm fluororesin as a release layer. A film 1a having a circumference of 56.5 mm was used. The heater holder 1c has a pressurizing support stay (support member) 1b substantially at the center in the short direction.

  The pressure roller 3 includes a core metal 3a, a 3 mm-thick silicone rubber layer (hereinafter referred to as an elastic layer) 3b covering the outer periphery of the core metal 3a, and a 50 μm-thick PFA resin covering the outer periphery. And an elastic roller having an outer diameter of 20 mm having a layer (release layer) 3c. The pressure roller 3 is rotatably supported at both end portions of the cored bar 3a by a corresponding side plate of an apparatus frame (not shown) via a bearing (not shown). Above the pressure roller 3, a heating unit 1 in which the heater 2, the heater holder 1 c, the film 1 a and the like are integrally assembled is disposed in parallel with the pressure roller 3. Then, in the longitudinal direction of the film 1a, both ends of the heater 2 and both ends of the support stay 1b are supported by a pair of film end movement restriction flanges (movement restriction members), and the pair of flanges are connected to the apparatus frame. It is assembled to the corresponding side plate. The pair of flanges are pressed against the pressure roller 3 by a pressure spring (pressure means) (not shown). According to the applied pressure, the elastic layer 3b of the pressure roller 3 is deformed in a planar shape over the longitudinal direction, and the surface of the pressure roller 3 comes into contact with the surface of the film 1a according to the planar shape. As a result, the pressure roller 3 forms a nip portion (fixing nip portion, heating nip portion) N3 having a predetermined width with the film 1a.

  FIG. 4 is an explanatory diagram showing the configuration of the heater 2 and the temperature control system.

The heater 2 is formed in a plate shape with a low heat capacity. The heater 2 has an elongated substrate 2a made of an insulating ceramic substrate such as alumina or aluminum nitride, or a heat resistant resin substrate such as polyimide, PPS, or liquid crystal polymer. On the surface of the substrate 2a on the side of the film 1a, an energization heat generating resistance layer 2b made of Ag / Pd (silver palladium), RuO ₂ , Ta ₂ N or the like is formed along the longitudinal direction by screen printing or the like. Further, a protective layer 2c for protecting the resistance layer 2b is provided on the surface of the substrate 2a within a range that does not impair the thermal efficiency. It is desirable that the thickness of the protective layer 2c is sufficiently thin and the surface property is good. 2d is an electrode part and is electrically connected to the resistance layer 2b. Reference numeral 31 denotes a thermistor (temperature detection means) provided on the back surface of the substrate 2a (surface opposite to the resistance layer 2b). The thermistor 31 detects the temperature of the substrate 2a.

  The cleaning roller 5 is an aluminum roller having a diameter of 15 mm. The cleaning roller 5 is arranged in parallel with the film 1a so as to face the nip portion N3 in the radial direction of the film 1a. Then, shafts 5a provided at both ends of the cleaning roller 5 are rotatably supported on corresponding side plates of the apparatus frame via bearings (not shown). The bearing is biased toward the film 1a with a force of 1.9 N by a biasing spring (biasing member) (not shown), thereby bringing the outer peripheral surface (surface) of the cleaning roller 5 into contact with the surface of the film 1a. That is, the cleaning roller 5 is in contact with the surface of the film 1a at a position other than the nip portion.

  The backup roller 6 is disposed parallel to the cleaning roller 5 on the inner peripheral surface (inner surface) side of the film 1a, and supports the film 1a from the inner surface side of the film 1a at a position where the cleaning roller 5 contacts the surface of the film 1a. is there. This backup roller 6 has a plurality (12 pieces) of divided rollers (rotators) 6a formed in a cylindrical shape with a diameter of 4 mm by PFA resin, and an elongated support shaft 6b extending along the longitudinal direction of the film 1a. . Both ends of the support shaft 6b are fixed to corresponding side plates of the apparatus frame. The material of the support shaft 6a is a rigid metal or alloy. The plurality of divided rollers 6a that are rotatably held at a fixed position on the support shaft 6b are arranged in arcuate grooves 1b1 provided on the support stay 1b so as not to contact the support stay 1b. Each of the plurality of divided rollers 6a has an outer peripheral surface (surface) in contact with the inner surface of the film 1a.

  Next, the heat fixing operation of the fixing device 10 will be described.

  Based on the print start signal (image formation signal), the rotation of the pressure roller 3 is started, and the heater 2 starts to heat up. The pressure roller 3 is rotationally driven in the direction of the arrow by a fixing motor (drive source) M (FIG. 1). A rotational force acts on the film 1a by a frictional force between the surface of the pressure roller 3 and the surface of the film 1a due to the rotational driving of the pressure roller 3. As a result, as the pressure roller 3 rotates, the inner surface of the film 1a is in contact with the protective layer 2c of the heater 2 and slides in the nip portion N3 while following the outer direction of the heater holder 1c. Further, a rotational force acts on the cleaning roller 5 by a frictional force between the surface of the film 1a and the surface of the cleaning roller 5 due to the rotation of the film 1a. As a result, the cleaning roller 5 is driven to rotate in the direction of the arrow as the film 1a rotates. Further, a rotational force acts on the plurality of divided rollers 6a by the frictional force between the inner surface of the film 1a and the surfaces of the plurality of divided rollers 6a due to the rotation of the film 1a. As a result, the plurality of divided rollers 6a are driven to rotate in the direction of the arrow as the film 1a rotates.

  The heater 2 generates heat when energized from the temperature control unit 30 to the resistance layer 2b through the electrode layer 2d, and quickly rises to a predetermined set temperature (target temperature). Based on the output signal of the thermistor 31, the temperature control unit 30 controls energization of the resistance layer 2b so that the heater 2 is maintained at the set temperature. The film 1a is heated to the set temperature at the nip portion N3 by the heater 2.

  The recording material P carrying the unfixed toner image t is introduced into the nip portion N3 while the film 1a and the pressure roller 3 are rotated and the heater 2 is held at the set temperature (FIG. 1). The recording material P is nipped and conveyed at the nip portion N3, and the unfixed toner image t is heated and fixed on the recording material surface by receiving heat and pressure during the conveyance process. The recording material P that has passed through the nip portion N3 is separated from the surface of the film 1a and conveyed on the exit side of the nip portion N3.

  In the conveyance process in which the recording material P is nipped and conveyed by the nip portion N3, the toner of the unfixed toner image t carried by the recording material P wraps around the film 1a surface from the end of the recording material P, and the toner adheres to the film 1a surface. There are things to do. Hereinafter, toner adhered to the surface of the film 1a is referred to as offset toner. The offset toner is transferred from the surface of the film 1a to the surface of the cleaning roller 5 at the contact portion between the surface of the film 1a and the surface of the cleaning roller 5 during the rotation of the film 1a. Thereby, the offset toner is removed from the surface of the cleaning roller 5, and the surface of the film 1a is cleaned. On the other hand, offset toner is accumulated on the surface of the cleaning roller 5. When the amount of accumulated offset toner increases, the cleaning ability of the cleaning roller 5 decreases. For this reason, the cleaning capability of the cleaning roller 5 is maintained by exchanging the cleaning roller 5 for every 1000 heat fixing processes.

  The arrangement form of the plurality of divided rollers 6a in the backup roller 6 will be described in more detail.

  FIG. 5 is an explanatory view showing an arrangement form of a plurality of divided rollers 6 a in the backup roller 6.

  In general, as a standard size of recording paper (paper) as the recording material P, A series such as A4 and A3, B series such as B4 and B5, and North American series such as Ledger and Letter used in North America are assumed. The four standard sizes of A4, Letter, B5, and government-made postcards are particularly large in consumption and used in large-scale image formation. In FIG. 5, A4 is represented as standard A, Letter is represented as standard B, B5 is represented as standard C, and public postcards are represented as standard D.

  As shown in FIG. 5A, in this embodiment, the length and arrangement of the divided rollers 6a are selected so as to avoid the divided positions of the divided rollers 6a with respect to the above four standard shapes A to D. Specifically, twelve divided rollers 6a having a length of 20 mm are arranged in the longitudinal direction of the film 1a. In the twelve divided rollers 6a, the divided rollers 6a1 and 6a12 corresponding to the end portions of the fixed form A have divided positions c1 and c13 outside the end portions of the fixed form A. The division rollers 6a1 and 6a12 corresponding to the end portions of the fixed form B have division positions c1 and c13 outside the end portions of the fixed form B. The division rollers 6a2 and 6a11 corresponding to the end portions of the fixed form C have division positions c2 and c12 outside the end portions of the fixed form C. The division rollers 6a4 and 6a9 corresponding to the end portions of the fixed form D have division positions c4 and c10 outside the end portions of the fixed form D. Thus, the 12 division | segmentation rollers 6a are divided | segmented so that it may have a division | segmentation position outside the edge part of fixed form AD in the longitudinal direction of the film 1a.

  The length of the split roller 6a having a diameter of 4 mm is preferably 30 mm or less. As shown in FIGS. 5C and 5D, when the length of one roller a is longer than 30 mm, smooth rotation may not be performed. If the diameter of the division roller 6a is smaller than 4 mm, the tendency that smooth rotation is not performed is further increased. Therefore, the length of the division roller 6a needs to be further shorter than 30 mm.

  On the other hand, when the length of the division roller 6a is shorter than 20 mm, the number of the division rollers 6a increases and the number of gaps between the division rollers 6a increases. Further, in order to ensure smooth rotation for all of the plurality of divided rollers 6a, it is necessary to secure a large gap between the divided rollers 6a in consideration of variations in contact pressure between the divided rollers 6a and the film 1a. . Therefore, as shown in FIG. 5B, the division position between the division rollers a often overlaps the end portions of the standard shapes B to D. In that case, in order for the film 1a to escape to the dividing position between the dividing rollers a, that is, to deform so that the film 1a enters the dividing position, good contact between the surface of the film 1a and the surface of the roller 5 cannot be obtained, Easy cleaning failure.

  When the entire surface image is formed, as described above, it is difficult to fix the toner image on the end portion and end surface of the recording material P, and the offset toner tends to increase at the end portion of the recording material P. Therefore, when there is a division position of the division roller 6a at the end of the standard size recording material P as described above, there is a high possibility that image smearing due to poor cleaning occurs.

  In the fixing device 10 of this embodiment, the backup roller 6 has a plurality of divided rollers 6a in the longitudinal direction, and each of the divided rollers 6a rotates as the film 1a rotates. Therefore, the rotation of the film 1a is not hindered by the backup roller 6. Thereby, the contact between the surface of the cleaning roller 5 and the surface of the film 1a can be stabilized, so that the cleaning effect of the surface of the film 1a by the cleaning roller 5 can be sufficiently obtained.

  In addition, since the backup roller 6 has the division position of the division roller 6a outside the end portion of the standard recording material P, the most easily soiled portion on the surface of the film 1a can be reliably backed up by the division roller 6a.

  The number of division rollers 6a is not limited to 12, and can be arbitrarily set within a range in which the problems described with reference to FIGS. 5B to 5D can be solved.

  Table 1 shows the results of confirming the occurrence of image smear and film slip due to the offset toner when the backup roller 6 shown in FIGS. 5A to 5D is used in the fixing device 10.

  In Table 1, “this embodiment” is a case where a backup roller 6 having a divided roller 6a having a length of 20 mm shown in FIG. “Comparative example 1” is a case where a backup roller 6 having a divided roller a having a length of 10 mm shown in FIG. 5B is used. “Comparative example 2” is a case where a backup roller 6 having a divided roller a having a length of 40 mm shown in FIG. 5C is used. “Comparative Example 3” is a case where the backup roller 6 having a roller a having a length of 220 mm shown in FIG.

  As is apparent from Table 1, in the case of the present embodiment using the backup roller 6 having the 20 mm-long divided rollers 6a shown in FIG. It was confirmed that the occurrence of the occurrence can be prevented.

  Another example of the fixing device will be described.

  In this embodiment, members / portions common to the fixing device 10 of Embodiment 1 are denoted by the same reference numerals, and the description thereof is omitted. The same applies to Example 3.

  The fixing device 10 shown in the present embodiment is the fixing device according to the first embodiment, except that the two cleaning rollers 5 and the backup rollers 6 are provided, and the arrangement of the plurality of divided rollers 6a of the two backup rollers 6 is different. The configuration is the same as that of the device 10.

  FIG. 7 is a schematic cross-sectional view of an example of the fixing device 10 according to the present embodiment. FIG. 8 is an explanatory diagram showing an arrangement of a plurality of divided rollers 6a in the two backup rollers 6. As shown in FIG.

  In the fixing device 10 shown in this embodiment, cleaning rollers 5 are provided on the upstream side and the downstream side of the nip portion N3 in the rotation direction of the film 1a. Since the offset toner can be removed from the surface of the film 1a by the two cleaning rollers 5, the cleaning ability of the surface of the film 1a can be further enhanced.

  Two backup rollers 6 are provided between the two cleaning rollers 5 so as to sandwich the rollers 5 and the film 1a. The two backup rollers 6 that are in contact with the inner surface of the film 1a at positions facing the respective cleaning rollers 5 each have a plurality (21) of divided rollers 6a in the longitudinal direction of the film 1a. A plurality (21) of the divided rollers 6a of the two backup rollers 6 are arranged so that the divided positions c1, c2,..., C22 do not overlap in the longitudinal direction of the film 1a. With this arrangement, the portion of the divided position where cleaning defects are likely to occur is complemented by the respective divided rollers 6a of the two backup rollers 6, so that cleaning defects at the divided positions can be prevented.

  Moreover, compared with Example 1, it becomes possible to use the division | segmentation roller 6a with short length, and there exists an effect that it is easy to implement | achieve smooth rotation of the film 1a.

  Furthermore, since the short division roller 6a is easy to rotate, there is an advantage that a small fixing device 10 can be realized by selecting a smaller diameter roller.

  The backup roller 6 and the cleaning roller 5 are not limited to two and may be two or more.

  Another example of the fixing device will be described.

  The fixing device 10 shown in the present embodiment has the same configuration as the fixing device 10 of the first embodiment, except that two backup rollers 6 are arranged so as to sandwich the cleaning roller 5 and the film 1a.

  FIG. 9 is a schematic cross-sectional view of an example of the fixing device 10 according to the present embodiment.

  In the fixing device 10 shown in the present embodiment, the two backup rollers 6 have the same configuration as the two backup rollers 6 of the second embodiment. That is, the plurality of division rollers 6a of the two backup rollers 6 are arranged so that the division positions do not overlap in the longitudinal direction of the film 1a. Accordingly, as in the fixing device 10 of the second embodiment, the portion at the division position where the cleaning failure is likely to occur is complemented by the two division rollers 6a of the two backup rollers 6, so that the cleaning failure at the division position can be prevented. it can.

  Further, since the surface of the cleaning roller 5 comes into contact with the surface of the film 1a on the two backup rollers 6, a wide contact surface between the surface of the cleaning roller 5 and the surface of the film 1a can be secured, and there is an effect that more reliable cleaning can be performed.

  Further, similarly to the second embodiment, it is possible to use the divided roller 6a having a short length, and it is possible to realize the small fixing device 10 by selecting the divided roller 6a having a smaller diameter.

  The number of the cleaning rollers 5 is not limited to two and may be two or more.

Cross-sectional schematic diagram of the fixing device of Example 1 Front model diagram of the fixing device of Example 1 Model of longitudinal section of the fixing device of Example 1 Explanatory diagram showing heater configuration and temperature control system Explanatory drawing showing the arrangement | sequence form of the some division | segmentation roller in the backup roller of the fixing device of Example 1. FIG. Configuration model diagram of an example of an image forming apparatus Cross-sectional model diagram of the fixing device of Example 2 Explanatory drawing showing the arrangement | sequence form of the some division | segmentation roller in the two backup rollers of the fixing apparatus of Example 2. FIG. Cross-sectional model diagram of the fixing device of Example 3

Explanation of symbols

1a: fixing film, 3: pressure roller, 4: heater, 5: cleaning roller, 6: backup roller, 6a: divided roller

Claims (5)

A heating body, a sleeve-like flexible member that rotates in contact with the heating body, a pressure member that forms a nip portion with the flexible member sandwiched between the heating body, and a position other than the nip portion A cleaning member that contacts the surface of the flexible member, and a backup member that contacts the inner surface of the flexible member so as to sandwich the cleaning member and the flexible member. In an image heating apparatus for heating an image on the recording material while sandwiching and conveying the recording material and cleaning the surface of the flexible member by the cleaning member,
The backup member has a plurality of rotating bodies divided in a longitudinal direction perpendicular to the recording material conveyance direction of the flexible member, and the plurality of rotating bodies rotate in contact with the inner surface of the flexible member, respectively. An image heating apparatus. A heating body, a sleeve-like flexible member that rotates in contact with the heating body, a pressure member that forms a nip portion with the flexible member sandwiched between the heating body, and a position other than the nip portion And at least two cleaning members that are in contact with the surface of the flexible member, and each of the at least two cleaning members is in contact with the inner surface of the flexible member so as to sandwich the cleaning member and the flexible member. An image heating apparatus that heats an image on the recording material while sandwiching and conveying the recording material at the nip portion, and cleaning the surface of the flexible member by the cleaning member. There,
Each of the at least two backup members has a plurality of rotating bodies divided in a longitudinal direction perpendicular to the recording material conveyance direction of the flexible member, and the plurality of rotating bodies are respectively connected to the inner surface of the flexible member. An image heating apparatus that rotates in contact with the image heating apparatus. A heating body, a sleeve-like flexible member that rotates in contact with the heating body, a pressure member that forms a nip portion with the flexible member sandwiched between the heating body, and a position other than the nip portion A cleaning member that contacts the surface of the flexible member, and at least two backup members that contact the inner surface of the flexible member so as to sandwich the cleaning member and the flexible member, An image heating apparatus that heats an image on the recording material while nipping and conveying the recording material at a nip portion and cleans the surface of the flexible member by the cleaning member,
Each of the at least two backup members has a plurality of rotating bodies divided in a longitudinal direction perpendicular to the recording material conveyance direction of the flexible member, and the plurality of rotating bodies are respectively connected to the inner surface of the flexible member. An image heating apparatus that rotates in contact with the image heating apparatus.   5. The image heating apparatus according to claim 3, wherein, in the at least two backup members, the plurality of rotating bodies are divided so that division positions do not overlap in the recording material conveyance direction. 6. .   The plurality of rotating bodies are divided so as to have a division position outside an end portion of the recording material in a longitudinal direction perpendicular to the recording material conveyance direction of the flexible member. The image heating apparatus according to claim 4.