JP2013105081A - Fixing device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To solve a problem in which: when a paper conveyance speed is increased to fix multiple media in high quality at a high speed, a high charge of local static electricity that generates on a roller surface layer gives disturbance by a static electric force to toner on a recording medium immediately before fixing, and thereby causing a decrease in quality such as a line-like image defect and the like.SOLUTION: A discharging roller 46 having a conductive release layer (peeling layer) 46b on an outermost layer is brought into contact with a pressure roller 32. A discharging needle 48 is brought into contact with the discharging roller and the discharging needle is dropped to an earth.

Description

  The present invention is mounted on an image forming apparatus such as an electrophotographic system or an electrostatic recording system (copying machine, printer, facsimile, composite function machine thereof) and supported on a recording material (recording paper: recording medium). The present invention relates to an image heating apparatus that heats an unfixed developer image and fixes it as a fixed image.

  Conventionally, as an image fixing device in an electrophotographic image forming apparatus, a heat roller pair type apparatus using a heating roller (heating rotator) and a pressure roller (pressure rotator) is generally used. This is a method in which a recording material carrying a toner image as an unfixed developer image is nipped and conveyed at a nip, which is a pressure contact portion between a heating roller and a pressure roller, and fixed as a fixed image by heating and pressing. .

  In recent years, in order to achieve a wide range of fixing properties for various types of media (recording materials), the heating roller is made of an aluminum or iron core, an elastic layer made of silicone rubber or fluororubber, and a surface layer made of a fluororesin tube or coating. It has a mold layer.

  In addition, the width of the nip formed by the heating roller and the pressure roller is made variable by automatically changing the pressure contact pressure between the heating roller and the pressure roller to an arbitrary pressure. As a result, by controlling the amount of heat and pressure applied to the medium, appropriate fixing conditions are set for each medium, and high-quality toner fixing is provided.

  However, in recent years, high productivity has been demanded in accordance with high-quality fixing properties, and the types of corresponding media are constantly increasing. In order to achieve high productivity, the conveyance speed of the recording material increases, and accordingly, the width of the nip portion formed by the heating roller and the pressure roller needs to be increased. In order to form a large nip width, it is necessary to increase the pressure contact force of the heating roller and the pressure roller.

  In the case where the roller surface layer and the recording material come into contact with each other and are peeled after pressure is applied, the static electricity is generated on the roller surface layer as the pressure is higher and the peeling speed is higher. That is, in order to achieve high productivity, the pressure contact force is increased, and when the conveying speed is high, a large amount of static electricity is generated on the roller surface layer, and when the trailing edge of the recording material is peeled off from the roller, the peeling occurs. At the position, an excessively charged state occurs on the roller surface layer.

  When an excessively charged state as described above occurs on the roller surface layer, a nip in which an unfixed toner image is formed on the surface and the recording material conveyed to the fixing device is formed by a heating roller and a pressure roller. The following phenomenon may occur when entering the part. That is, a phenomenon occurs in which the toner that is electrostatically adhered to the recording material receives an external force due to excessive charging of the roller surface layer, and the toner position is shifted. Due to this phenomenon, there is a problem that line-shaped image disturbance occurs particularly at the roller surface position located at the rear end of the preceding recording material in an intermediate density image.

  In order to solve the above-described problems, the present applicant has previously proposed a fixing device as disclosed in Patent Document 1. In this fixing device, a neutralizing needle is provided in the vicinity of the pressure roller with a predetermined gap for the purpose of neutralizing the charged surface layer of the pressure roller.

JP-A-7-295427

  The present invention is a further development of the above prior art. That is, in recent years, there has been an increasing demand for image fixing of high-quality images on various media, particularly in the field of commercial printing. In order to improve the fixing quality, it is necessary to appropriately set the temperature of the heating roller and the pressure roller and the pressure of the nip formed by the heating roller and the pressure roller depending on the rigidity and type of the recording material. However, changing the pressure contact means changing the position of the pressure roller, and changing the pressure roller temperature means changing the expansion amount of the pressure roller to change the outer surface diameter of the roller. Will change.

  As the roller position and roller outer diameter change, the gap with the static elimination needle changes, and the static elimination capability of the static elimination means is not stable due to the state of the roller at that time, and the maximum effect cannot be exhibited. Further improvement of the point is desired. In addition, it is necessary to provide an adjustment mechanism in order to produce a static elimination effect on the roller surface layer whose position changes, which increases the number of assembly steps, increases the complexity of the device, and increases costs. Further improvement is desired. The present invention meets the above needs.

  In order to achieve the above object, a typical configuration of the fixing device according to the present invention is provided with a non-conductive layer on the surface and is in contact with the image carrying surface of a recording material carrying an unfixed developer image. And a rotatable heating rotator for fixing an unfixed developer image as a fixed image and a non-conductive layer on the surface, and pressurizing the heating rotator to sandwich and convey the recording material A rotatable pressure rotator that forms a nip portion, and a conductive layer on a surface thereof, and is disposed in pressure contact with at least one of the heating rotator and the pressure rotator. A rotatable static elimination rotator for neutralizing electric charges on a surface layer of the rotator or pressurizing rotator, and a static elimination means disposed in contact with the static elimination rotator and grounded. And

  According to the present invention, even if the position of the heating rotator or the pressure rotator and the outer diameter change due to temperature occur, the static elimination rotator is infinitely stable between the heating rotator or the pressure rotator. Create a gap. Then, the charge on the surface of the heating rotator or the pressure rotator is moved to the surface of the static rotator at an appropriate gap according to the charge amount of the heating rotator or the pressure rotator, and It is grounded by the neutralization needle that has been positioned.

  As a result, the surface layer of the heating rotator or the pressure rotator can be neutralized, and the unfixed developer image on the electrostatically attached recording material can be charged excessively on the surface of the heating rotator or the pressure rotator. It is possible to perform high-quality fixing without being disturbed by.

1 is a schematic configuration diagram of an image forming apparatus in Embodiment 1. FIG. FIG. 3 is an enlarged schematic cross-sectional view of a fixing device. It is an expansion perspective view of the one end side of a static elimination unit. It is explanatory drawing of the static elimination process of a static elimination unit. FIG. 10 is a schematic configuration schematic diagram of a fixing device in Embodiment 5.

  Hereinafter, the present invention will be described more specifically with reference to examples. In addition, although an Example is an example of the best embodiment in this invention, this invention is not limited by an Example.

[Example 1]
(1) Image Forming Apparatus FIG. 1 is a schematic configuration diagram of an example of an image forming apparatus in which an image heating apparatus according to the present invention is mounted as a fixing device 13. This image forming apparatus is a full-color laser beam printer using an electrophotographic system, and an image corresponding to electrical image information input from a host device (not shown) such as a personal computer / image reader to a controller (control means: not shown). Are formed on the recording material S and output.

  In the apparatus, first to fourth four image forming portions P (Pa, Pb, Pc, Pd) are provided side by side, and each image forming portion forms toner images of different colors, latent image formation, development, and transfer. The recording material S is formed through the electrophotographic process.

  Each image forming unit P includes a dedicated image carrier, in this example, an electrophotographic photosensitive drum 1 (1a, 1b, 1c, 1d: hereinafter referred to as a drum). The drum 1 is rotationally driven at a predetermined speed in the clockwise direction indicated by an arrow, and a toner image of each color is formed on each drum 1. Adjacent to each drum 1 is an intermediate transfer belt (hereinafter referred to as a belt) 8 which is an intermediate transfer member. The toner images of the respective colors formed on the respective drums 1 are superimposed on the belt 8 and are primarily transferred, and further transferred onto the recording material S at the secondary transfer portion.

  The recording material S to which the toner image has been transferred is introduced into the fixing device 13 and subjected to fixing processing of the toner image by heating and pressurization, and then discharged onto the discharge tray 17 outside the device as an image formed product (full color print). The

  On the outer periphery of each drum 1, there are a drum charger 2 (2a, 2b, 2c, 2d), a developing device 4 (4a, 4b, 4c, 4d), and a primary transfer charger 5 (5a, 5b, 5c, 5d) and a drum cleaner 6 (6a, 6b, 6c, 6d) are provided. The drum charger 2 uniformly charges the peripheral surface of the drum 1 to a predetermined polarity and potential.

  A laser scanner 3 (3a, 3b, 3c, 3d) is installed above each drum 1. Although not shown in the drawing, each laser scanner 3 has a light source device, a polygon mirror, an fθ lens, and the like. The laser light emitted from the light source device is scanned by rotating the polygon mirror, the light beam of the scanning light is deflected by the reflection mirror, and is condensed and exposed on the generatrix of the drum 1 by the fθ lens. The drum 1 charged by the drum charger 2 is subjected to scanning exposure with laser light, whereby an electrostatic latent image corresponding to an image signal is formed on the drum 1.

  Developers 4a, 4b, 4c, and 4d are filled with predetermined amounts of yellow, magenta, cyan, and black toners as developers. Each developing device 4 is appropriately replenished with toner from a replenishing device 7 (7a, 7b, 7c, 7d). Each developing device 4 develops the latent image on the corresponding photosensitive drum 1 and visualizes it as a yellow toner image, a magenta toner image, a cyan toner image, and a black toner image. The belt 8 is stretched around a driving roller 9, a secondary transfer counter roller 10, and a tension roller 11, and is driven to rotate at the same peripheral speed as each drum 1 in the clockwise direction indicated by an arrow.

  The yellow toner image of the first color formed and supported on the drum 1a of the first image forming portion Pa is intermediately transferred to the belt 8 in the process of passing through the nip portion (primary transfer portion) between the drum 1a and the belt 8. Is done. That is, intermediate transfer is performed on the outer peripheral surface of the belt 8 by the electric field and nip pressure formed by the primary transfer bias applied to the primary transfer charger 5a.

  Hereinafter, similarly, the second color magenta toner image of the second image forming unit Pb, the third color cyan toner image of the third image forming unit Pc, and the fourth color of the fourth image forming unit Pd. Black toner images are sequentially transferred onto the belt 8 in a superimposed manner. As a result, an unfixed composite color toner image corresponding to the color image information input to the apparatus is formed on the belt 8. The surface of the drum 1 after the primary transfer of the toner image to the belt 8 is subjected to the removal (cleaning) of the primary transfer residual toner by the drum cleaner 6 and is subsequently prepared for the subsequent formation of the next latent image.

  A secondary transfer roller 12 is pressed against the secondary transfer counter roller 10 with a belt 8 interposed therebetween. The secondary transfer roller 12 is disposed in parallel with the secondary transfer counter roller 10 so as to be in contact with the belt 8 in parallel. A nip portion between the belt 8 and the secondary transfer roller 12 is a secondary transfer portion. A predetermined secondary transfer bias is applied to the secondary transfer roller 12 at a predetermined control timing.

  Transfer of the composite color toner image superimposed and transferred onto the belt 8 to the recording material S is performed by introducing the recording material S into the secondary transfer portion. That is, the recording material S is separated and fed at a predetermined control timing by the operation of the feeding mechanism from the first or second paper feeding cassette 19a or 19b. The recording material S is conveyed by the sheet path 20, passes through the registration roller 21 and the pre-transfer guide 22, and is fed to the secondary transfer portion at a predetermined control timing, and at the same time, the secondary transfer roller 12 receives the secondary transfer A transfer bias is applied. The composite color toner image is collectively transferred from the belt 8 to the recording material S by the secondary transfer bias.

  The secondary transfer residual toner and other foreign matters remaining on the belt 8 are wiped off with a cleaning web (nonwoven fabric) of a belt cleaner 18 in contact with the surface of the belt 8.

  The recording material S that has undergone the secondary transfer of the unfixed composite color toner image at the secondary transfer portion is separated from the belt 8 and introduced into the fixing device 13 and undergoes a fixing process of the toner image by heating and pressing. Then, the recording material S exits the fixing device 13, is transported by the transport roller pair 14, passes the upper side of the flapper 15, and is discharged onto the discharge tray 17 outside the device by the discharge roller 16 (in the case of the single-sided image forming mode). ).

  In the double-sided image forming mode, the recording material S on which the single-sided image has been formed (first-side image formed) exiting the fixing device 13 is conveyed by the conveying roller pair 14 and the reverse path 23 is switched by the flapper 15 whose posture has been switched. Led to. Then, the recording material S is reversed by a reversing roller (switchback roller) 24 and guided to a double-sided path 25, and is again introduced into the secondary transfer portion through the path of the sheet path 20, the registration roller 21, and the pre-transfer guide 22. . As a result, the recording material S receives the secondary transfer of the toner image on the second side.

  Then, the recording material S is separated from the belt 8 and is again introduced into the fixing device 13 and undergoes a toner image fixing process on the second surface. The flapper 15 is switched back to the original posture while the recording material is forming a double-sided image. As a result, the recording material S on which the double-sided image has been formed exiting the fixing device 13 is transported by the transport roller pair 14, passes the upper side of the flapper 15, and is discharged onto the discharge tray 17 outside the device by the discharge roller 16.

(2) Fixing device 13
FIG. 2 is an enlarged schematic cross-sectional view of the fixing device 13. The fixing device 13 is a heat roller pair type device. The fixing device 13 is a rotatable heating rotating body that contacts and heats the image carrying surface of the recording material S carrying an unfixed developer image (toner image) t and fixes the unfixed developer image as a fixed image. As a heating roller (fixing roller) 31. Further, a pressure roller 32 is provided as a rotatable pressure rotator for forming a nip portion (fixing nip portion) N that pressurizes the heating roller 31 to sandwich and convey the recording material S.

  The pressure roller 31 includes a hollow metal core 31a, an elastic layer 31b formed on the outer peripheral surface of the metal core, and a release layer (non-conductive layer) formed on the outer peripheral surface of the elastic layer. A peeling layer, a surface layer) 31c. In this embodiment, the metal core 31a is an aluminum pipe, the elastic layer 31b is a silicone rubber layer, and the release layer 31c is a non-conductive fluororesin tube (more specifically, a PFA tube).

  The heating roller 31 is disposed such that one end side and the other end side of the cored bar 31a are rotatably supported by bearings between side plates on one end side and the other end side of the fixing device housing 30 via bearings (not shown). Yes. The heating roller 31 is rotationally driven at a predetermined speed in a counterclockwise direction indicated by an arrow by a driving force of a driving source (not shown) controlled by a controller (not shown).

  The pressure roller 32 includes a hollow cored bar 32a, an elastic layer 32b formed on the outer peripheral surface of the cored bar, and a release layer (non-conductive layer) formed on the outer peripheral surface of the elastic layer. A peeling layer, a surface layer) 32c. In this embodiment, the core metal 32a is an iron pipe, the elastic layer 32b is a silicone rubber layer, and the release layer 32c is a non-conductive fluororesin tube (more specifically, a PFA tube).

  The pressure roller 32 is arranged below the heating roller 31 in parallel with the heating roller 31, and the one end side and the other end side of the cored bar 32 a are between the side plates on the one end side and the other end side of the fixing device housing 30, respectively. A bearing is rotatably held via a bearing (not shown).

  The bearings on one end side and the other end side of the pressure roller 32 have a degree of freedom of sliding movement in a direction toward the heating roller 31 and a direction away from the heating roller 31, respectively. These bearings are pressed against the elasticity of the elastic layer 31 b of the heating roller 31 and the elastic layer 32 b of the pressing roller 32 in the direction toward the heating roller 31 by the pressing force of the pressing unit 33. As a result, the upper surface side of the pressure roller 32 is pressed against the lower surface side of the heating roller 31, and a nip portion N having a predetermined width is formed between the rollers 31 and 32 in the recording material conveyance direction.

  In the present embodiment, the pressure unit 33 adjusts the rotation angle of the pressure cam 33 a to move the roller 33 b up and down to adjust the pressure of the nip N formed by the heating roller 31 and the pressure roller 32. Can be changed (increase / decrease). Then, the controller controls the drive source (not shown) for driving the pressure cam 33a according to the stiffness and type of the recording material S used to pass the paper in order to improve the fixing quality. The rotation angle of the pressure cam 33a is adjusted so that the pressure contact pressure is appropriately set. The pressure roller 32 rotates in the clockwise direction of the arrow following the rotation of the heating roller 31 in a state where it is in pressure contact with the heating roller 31.

  A heater 31 d for heating the heating roller 31 from the inside is provided inside the cored bar 31 a of the heating roller 31. An external heating unit 34 for heating the heating roller 31 from the outside is disposed outside the heating roller 31. The external heating unit 34 in the present embodiment is in contact with the outer surface of the heating roller 31 in parallel with the heating roller 31 and heats the heating roller 31 from the outside by two first and second external heating rollers 34a. 34b. The two rollers 34a and 34b are disposed such that one end side and the other end side thereof are rotatably supported by bearings between side plates on one end side and the other end side of the frame 34c of the external heating unit 34, respectively.

  The first and second external heating rollers 34a and 34b are hollow metal pipes, respectively, and heaters 34d and 34e are provided therein. In the external heating unit 34, cleaning rollers 34f and 34g are arranged in parallel with the rollers 34a and 34b while being pressed against the outer surfaces of the first and second external heating rollers 34a and 34b, respectively. The frame 34c of the external heating unit 34 is pressed in the direction of the pressure roller 31 by the pressure spring 34h, and the first and second external heating rollers 34a and 34b are pressed against the outer surface of the heating roller 31 by a predetermined pressure. It is pressed by.

  The first and second external heating rollers 34 a and 34 b rotate following the rotation of the heating roller 31. The cleaning rollers 34f and 34g are rotated by the rotation of the external heating rollers 34a and 34b, respectively, to clean the external heating rollers 34a and 34b.

  The heating roller 31 is heated from the inside by energizing the heater 31d. The heating roller 31 is heated from the outside by the heat of the first and second external heating rollers 34a and 34b, which is heated by energizing the heaters 34d and 34e of the external heating unit 34. In addition, a heater 32 d is provided inside the cored bar 32 a of the pressure roller 32. The pressure roller 32 is heated from the inside by energizing the heater 32d.

  The controller heats the heating roller 31 and the pressure roller 32 by energizing the heaters 31d, 34d, 34e, and 32d, respectively, while the heating roller 31 and the pressure roller 32 are rotating. Then, the controller adjusts the surface temperature of the heating roller 31 and the pressure roller 32 to an appropriate temperature depending on the rigidity and type of the recording material S used to pass the paper in order to improve the fixing quality. The power supplied to the heaters 31d, 34d, 34e, and 32d is adjusted.

  Reference numeral 35 denotes a cleaner unit for cleaning the surface of the heating roller 31. A web feed shaft portion 35b that holds the cleaning web 35a in a roll form, a web winding shaft portion 35c, and a pressing roller 35d that presses the web portion between the shaft portions 35b and 35c against the outer surface of the heating roller 31 are provided. The toner offset to the surface of the heating roller 31 is wiped by the web portion pressed against the heating roller 31 by the pressing roller 35d, and the surface of the heating roller is cleaned. The web portion pressed against the heating roller 31 is gradually renewed by gradually feeding the web 35a from the feeding shaft portion 35b side to the winding shaft portion 35c side.

  An inlet guide 36 is disposed upstream of the nip portion N in the recording material conveyance direction a. A heating roller separation claw 37 and a pressure roller separation claw 38 are disposed downstream of the nip portion N in the recording material conveyance direction a. The heating roller separation claw 37 is a member that leaves the nip portion N and peels off the recording material attached to the surface layer 31 c of the heating roller 31. The pressure roller separation claw 38 is a member that leaves the nip portion N and peels off the recording material attached to the surface layer 32 c of the pressure roller 32.

  Further, a transport roller pair 39 for transporting the recording material is disposed immediately after the separating portion composed of the separation claws 37 and 38 in the recording material transport direction. A transport path 40 is provided on the downstream side of the transport roller pair 39 in the recording material transport direction.

  The recording material S conveyed to the fixing device 13 from the side of the image forming mechanism that forms an unfixed toner image t on the recording material S is guided by the entrance guide 36 and introduced into the nip portion N. The controller controls the pressurizing unit 34 according to the rigidity and type of the recording material S used for passing the paper through the apparatus, and adjusts the press contact pressure of the nip portion N to an appropriate pressure. Further, the controller drives the heating roller 31 and adjusts the surface temperature of the heating roller 31 and the pressure roller 32 to an appropriate temperature depending on the rigidity and type of the recording material S used for passing the sheet through the apparatus. .

  In this state, the recording material enters the nip N and is nipped and conveyed, whereby the unfixed toner image t is fixed as a fixed image on the recording material by heating and pressurization in the nip portion N. The recording material S exiting the nip portion N is separated from the surface of the heating roller 31 or the pressure roller 32 by the separation claws 37 and 38, relayed by the conveying roller pair 39, and sent out of the fixing device 13 through the conveying path 40. It is.

(3) Static elimination structure of the pressure roller 32 A static elimination unit 41 for neutralizing the surface of the pressure roller 32 is disposed below the pressure roller 32. The charge eliminating unit 41 will be described in detail with reference to FIGS. FIG. 3 is an enlarged perspective view of one end side of the static elimination unit 41. The other end also has a symmetrical structure with the one end. FIG. 4 is an explanatory diagram of the charge removal process of the charge removal unit 41.

  Reference numeral 42 denotes a metal stay disposed below the pressure roller 32 in parallel with the pressure roller 32, and is fixedly supported between the side plates on one end side and the other end side of the fixing device housing 30. Yes. On the upper side of the stay 42, a long sheet metal neutralizing needle attaching member 43 is fixedly disposed along the pressure roller 32. The static elimination needle mounting member 43 is electrically connected to the stay 42. On one end side and the other end side of the static elimination needle mounting member 43, bearing support members 43 that hold the belling 45 are arranged so as to be slidable in the vertical direction.

  And the static elimination roller 46 is rotatably hold | maintained and arrange | positioned between the bellows 45 each hold | maintained at the bearing support member 43 of the one end side and the other end side. The static elimination roller 46 is a rotatable static elimination rotator that is disposed in pressure contact with the pressure roller 32 and neutralizes charges on the surface layer of the pressure roller 32. In this embodiment, the static elimination roller 46 has a cored bar 46a made of aluminum and a release layer (peeling layer) 46b as a conductive layer provided on the outer periphery thereof. In this embodiment, the release layer 46b is a fluororesin tube to which a conductive material is added. More specifically, it is a PFA tube containing a conductive material such as carbon and has conductivity.

  Coil springs (biasing means) 47 are compressed and disposed between the lower surface of the bearing support member 44 on one end side and the upper surface of the stay 42, respectively. As a result, the bearing support members 44 on the one end side and the other end side are respectively pushed up and biased in a direction substantially facing the central axis of the pressure roller 32 by the compression reaction force of the coil spring 47, so that the charge removal roller 46 is pressed. 32 is brought into pressure contact with the entire length. The static elimination roller 46 rotates following the rotation of the pressure roller 32.

  With the above configuration, the static eliminating roller 46 that is in pressure contact with the outer peripheral surface of the pressure roller 32 follows the change in the position of the outer peripheral surface of the pressure roller 32 depending on the temperature of the pressure roller 32 and the pressure state, and always pressurizes the pressure roller 32. Thus, it is possible to create a state in which the outer peripheral surface of the static elimination roller 46 is in pressure contact with the outer peripheral surface.

  In the vicinity of the static elimination roller 46, a static elimination needle 48 is provided so that the tip of the static elimination roller 46 is in contact with the outer peripheral surface. That is, the static elimination needle attaching member 43 is provided with a static elimination needle 48 as a static elimination means that is disposed in contact with the static elimination roller 46 and grounded. The static elimination needle 48 is a long member along the static elimination roller 46, and is a static elimination needle array member in which a large number of static elimination needles are arranged along the length of the metal plate between the metal plates which are stacked one above the other.

  The static elimination needle 48 is arranged in parallel with the static elimination roller 46 and is attached on the static elimination needle mounting member 44 at a position where the static elimination needle tip 48 a can contact the static elimination roller 46 regardless of the position of the static elimination roller 46. . Reference numeral 49 denotes a fixing screw for fixing the static elimination needle 48 to the static elimination needle attaching member 43.

  Next, the static electricity removal process on the surface layer of the pressure roller 32 will be described in detail with reference to FIG. A neutralizing roller 46 is pressed against the outer peripheral surface of the pressure roller 32 and rotates in the direction of the arrow. A region L (wedge-shaped space region) in which the gap continuously changes is formed on the upstream side in the roller rotation direction of the pressure nip portion between the pressure roller 32 and the charge removal roller 46.

  Therefore, the static electricity charged on the surface layer 32c of the pressure roller 32 moves the electric charge e to the release layer 45b by the conductive PFA tube which is the surface layer of the static elimination roller 46 at an optimum gap portion depending on the magnitude of the static electricity. . The electric charge e that has moved to the release layer 45b moves on the release layer 45b, passes through the static elimination needle 48, and is dropped from the static elimination needle attachment member 43 to the apparatus main body (earth G) via the stay 42.

  That is, even if the outer diameter changes due to the position of the pressure roller 32 or the temperature, the static elimination roller 46 generates a stepless stable gap (wedge-like space region L) between the pressure roller 32 and the pressure removal roller 46. As a result, the charge e on the surface of the pressure roller moves to the surface of the static elimination roller 46 at an appropriate gap according to the charge amount of the pressure roller 32 and is grounded by the static elimination needle 48 positioned directly on the static elimination roller 46. By dropping to G, the roller surface layer can be surely eliminated. As a result, high-quality fixing can be performed without disturbing unfixed toner t on the electrostatically attached recording material due to excessive charging of the roller surface layer.

  Thus, static electricity strongly charged on the roller surface layer is stably eliminated under optimum conditions, thereby eliminating a partially charged state on the roller surface layer, and disturbance due to static electricity on the recording material S on which the unfixed toner t is placed. To give away. As a result, the recording material to which the toner has been transferred can be fixed with high quality.

[Example 2]
FIG. 5 is a schematic diagram of the configuration of the second embodiment. In this embodiment, the fixing device of the first embodiment is further provided with a cleaning means 50 for removing the deposits on the surface of the static elimination roller 46 which is a static elimination rotating body. In this embodiment, the cleaning means 50 is a cleaning roller disposed in pressure contact with the static elimination roller 46. The cleaning roller 50 is rotated by the rotation of the neutralizing roller 46 to clean the neutralizing roller 46. The cleaning means 50 is not limited to a roller body, but may be other forms such as a pad or a brush.

  By cleaning the surface layer of the static elimination roller 46 with the cleaning means 50, a local gap change due to a foreign substance in a gap (wedge-like space region L) generated on a continuous floor between the static elimination roller 46 and the pressure roller 32 is obtained. Can be eliminated. As a result, it is possible to generate a more stable and stepless and stable gap, and thus it is possible to perform higher-quality fixing.

[Other matters]
1) Although the neutralization configuration for the pressure roller 32 is shown in the above-described first and second embodiments, the heating roller 31 may be configured as an apparatus that applies the same neutralization configuration. Moreover, it is also possible to adopt a device configuration in which a similar static elimination configuration is applied to both the pressure roller 32 and the heating roller 31. That is, an apparatus configuration in which the above-described static elimination configuration is applied to at least one of the pressure roller 32 and the heating roller 31 can be obtained.

  2) The heating rotator 31 and the pressure rotator 32 are not limited to roller bodies, and may be configured as endless belt bodies.

  31 ... Heating rotator, 31c ... Surface non-conductive layer, 32 ... Pressure rotating body, 32c ... Surface non-conductive layer, N ... Nipping part, S ... Recording material, ... Unfixed developer image, 46... Static elimination rotator, 46 b... Conductive layer on the surface, 48..

Claims (3)

A non-conductive layer is provided on the surface, and heating is possible to rotate by contacting the image bearing surface of the recording material carrying an unfixed developer image and fixing the unfixed developer image as a fixed image. Body,
A non-conductive layer is provided on the surface, and a rotatable pressure rotator that pressurizes the heating rotator and forms a nip portion that sandwiches and conveys the recording material; and
A conductive layer is provided on the surface, and is disposed in pressure contact with at least one of the heating rotator and the pressurizing rotator to neutralize charges on the surface of the heating rotator or the pressurizing rotator. A rotatable static elimination rotor,
A neutralizing means disposed in contact with the static elimination rotating body and grounded;
A fixing device. The fixing device according to claim 1, further comprising a cleaning unit that removes deposits on the surface of the static elimination rotator. The fixing device according to claim 1, wherein the nonconductive layer is a nonconductive fluororesin tube, and the conductive layer is a fluororesin tube to which a conductive material is added.