JP4852000B2 - Fixing device and image forming apparatus including the fixing device - Google Patents

Description

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

  In an image forming apparatus such as a printer, a copier, a facsimile machine, or a multi-function machine that forms an image by electrophotography, the surface of the photosensitive drum is charged by a charging roller, and an LED (Light Emitting Diode) head is formed on the charged surface. An electrostatic latent image is formed by exposure, and a toner image is formed by electrostatically attaching the toner thinned on the developing roller to the electrostatic latent image. The toner image is formed by a transfer roller. It is transferred to a recording medium. Then, the toner image transferred to the recording medium is fixed on the recording medium in the fixing device and then discharged to the outside of the device.

  In the fixing device, the toner image is heated when the recording medium on which the toner image is transferred passes through a nip formed between the fixing roller and a pressure roller pressed against the fixing roller. In addition, it is pressurized and fixed on the recording medium. The surfaces of the fixing roller and the pressure roller are covered with a fluororesin layer for improving toner releasability. Accordingly, the recording medium is easily charged due to conveyance friction or the like when the recording medium passes through the nip portion. When the charged recording medium is discharged from the fixing device, a conveyance defect such as a stack defect occurs due to the electrostatic charge of the recording medium. In view of this, a fixing device is provided in which a charge-removing brush serving as a charge-removing unit is disposed so as to come into contact with the recording medium when passing through the nip portion in order to remove the charge charged on the recording medium (for example, Patent Document 1). reference.).

In addition, although the fixing means for fixing a static elimination brush is not specifically shown in patent document 1, the brush part is a brush support part by one adhesive surface of an electroconductive double-sided adhesive tape. Further, the other adhesive surface of the conductive double-sided adhesive tape is fixed by adhering to a grounded metal plate frame for supporting the fixing roller and the pressure roller. Then, when the charge eliminating brush comes into contact with the surface of the recording medium, the charge existing on the surface of the recording medium is removed.
JP 2002-91217 A

  However, in the conventional fixing device, since the sheet metal frame has high thermal conductivity, it easily receives heat from the fixing device, and becomes high during operation of the fixing device. Therefore, the temperature of the pressure-sensitive adhesive tape that fixes the static eliminating brush rises, and the pressure-sensitive adhesive easily peels off. As a result, the contact between the static elimination brush and the sheet metal frame becomes unstable, the conduction becomes incomplete, and the static elimination of the recording medium by the static elimination brush cannot be performed stably.

  The present invention solves the problems of the conventional fixing device, and presses and holds a static eliminating member between a frame member that supports the fixing member and the pressure member and a cover member that covers the frame member. Therefore, the fixing device is capable of reliably grounding the static eliminating member without causing poor conduction, stably removing the medium, and reliably preventing the occurrence of poor conveyance of the medium. And an image forming apparatus including the fixing device.

  In order to solve this problem, in the fixing device of the present invention, a fixing member that heats a medium to fix an image formed on the medium, and a pressure that is pressed against the fixing member and pressurizes the medium to the fixing member. A fixing device comprising: a member; a frame member that supports the fixing member and the pressure member; a cover member that covers the frame member; and a static elimination member that removes static electricity accumulated in the medium. It is clamped and held between the frame members.

  According to the present invention, the fixing device presses and holds the static eliminator member between the frame member that supports the fixing member and the pressure member and the cover member that covers the frame member. As a result, the continuity failure does not occur, and the neutralization member can be reliably grounded, the neutralization of the medium can be performed stably, and the occurrence of the conveyance failure of the medium can be surely prevented.

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

  FIG. 2 is a schematic side view showing the image forming apparatus provided with the fixing device according to the first embodiment of the present invention.

  In the figure, reference numeral 10 denotes an image forming apparatus according to the present embodiment. For example, any type of image forming apparatus such as a printer, a copying machine, a facsimile machine, or a multi-function machine that forms an image on a recording medium 15 by electrophotography. There may be. In the present embodiment, the image forming apparatus 10 may be of any type as long as the fixing device 30 can be used.

The recording medium 15 as a medium is, for example, plain paper, but in addition to plain paper, an OHP (Over Head Projector) sheet, a card, a postcard, and a scale (hail) amount of about 200 [g / m ² ] Special paper such as thick paper, envelopes, and coated paper with a large heat capacity may be used. The image forming apparatus 10 may form a monochrome image or a color image. Here, the image forming apparatus 10 forms a color image by a tandem method. A case where the printer is the printer will be described.

  The image forming apparatus 10 is arranged along the conveyance direction of the recording medium 15 and forms image toners 11Bk, 11Y, 11M, and 11C that form four color toner images of black, yellow, magenta, and cyan on the recording medium 15. Have The image forming units 11Bk, 11Y, 11M, and 11C respectively include photosensitive drums 12Bk, 12Y, 12M, and 12C as image carriers that carry toner images of black, yellow, magenta, and cyan on the surface, and A charging device, a developing device, and a photoreceptor cleaning device (not shown) are provided. The image forming units 11 </ b> Bk, 11 </ b> Y, 11 </ b> M, and 11 </ b> C are integrally configured and can be detached from the image forming apparatus 10. Further, the upper cover 17 of the image forming apparatus 10 is provided to be openable and closable so that the image forming units 11Bk, 11Y, 11M, and 11C can be attached and detached.

  Further, the exposure devices 16Bk, 16Y, 16M and 16C made up of LED heads and the like are arranged facing the respective photosensitive drums 12Bk, 12Y, 12M and 12C and supported by the upper cover 17. Each of the exposure devices 16Bk, 16Y, 16M, and 16C exposes the surface of each of the photosensitive drums 12Bk, 12Y, 12M, and 12C to form an electrostatic latent image.

  Further, transfer rollers 13Bk, 13Y, 13M, and 13C are disposed so as to face each of the photosensitive drums 12Bk, 12Y, 12M, and 12C with the conveyance belt 14 interposed therebetween. The toner images of the respective colors formed on the surfaces of the photosensitive drums 12Bk, 12Y, 12M, and 12C are transferred to the recording medium 15 that is conveyed on the conveying belt 14 by the transfer rollers 13Bk, 13Y, 13M, and 13C.

  In addition, a paper feed cassette 18 that accommodates the recording medium 15 is disposed in the lower part of the image forming apparatus 10. A paper feed mechanism is disposed adjacent to the front end (right end in the figure) of the paper feed cassette 18. The sheet feeding mechanism includes sheet feeding rollers 21 a and 21 b and a separation roller 22, and separates and feeds the recording media 15 stacked in the sheet feeding cassette 18 one by one. In addition, conveyance rollers 23a and 23b are disposed above the sheet feeding mechanism.

  Further, a fixing device 30 is detachably disposed on the downstream side of the conveyor belt 14. The recording medium 15 discharged from the fixing device 30 is conveyed by the discharge roller 24 and then discharged onto the upper cover 17 by the discharge conveyance roller 25.

  Next, the configuration of the fixing device 30 will be described in detail.

  FIG. 1 is a cross-sectional view of the main part of the fixing device according to the first embodiment of the present invention. FIG. 3 is a cross-sectional view taken along the line ZZ in FIG. 3, and FIG. FIG. 4 is an exploded perspective view as seen from the recording medium ejection direction of the fixing device according to the first embodiment of the present invention, and FIG. 5 is a perspective view according to the first embodiment of the present invention. FIG. 6 is a cross-sectional view of the static elimination brush, FIG. 6 is an enlarged view of the support attachment opening of the static elimination brush in the first embodiment of the present invention, and FIG. 7 is the support attachment opening of the static elimination brush in the first embodiment of the present invention. It is an enlarged view which shows the other example.

  As shown in FIG. 1, the fixing device 30 includes a fixing roller 44 as a fixing member and a pressure roller 45 as a pressure member, and a nip portion N for fixing the unfixed toner image T to the recording medium 15. Is formed by pressing the pressure roller 45 against the fixing roller 44 by pressure means (not shown).

  The fixing roller 44 is, for example, a hollow roller having an outer diameter of about 25 [mm], and has a heat resistance elasticity of about 1.2 [mm] made of silicone rubber on the outer peripheral surface of an aluminum core. Further, a fluororesin layer having a thickness of about 30 [μm] as a release layer is formed on the outer peripheral surface of the layer. The core metal does not necessarily need to be made of aluminum, and may be made of other metals such as iron.

  The pressure roller 45 is, for example, a solid roller having an outer diameter of about 24 [mm], and a heat-resistant elastic layer having a thickness of about 5 [mm] made of foamed silicone rubber is formed on the outer peripheral surface of an iron core metal. Furthermore, a fluororesin layer having a thickness of about 30 [μm] is formed on the outer peripheral surface as a release layer.

  A thermistor as a temperature detection element (not shown) is provided near the surface of the fixing roller 44, and a halogen heater 51 as a heat source is provided inside the fixing roller 44. The heat source of the fixing roller 44 is not limited to the halogen heater 51, and induction heating or the like can be used.

  As shown in FIG. 4, side plates 34 a and 34 b as frame members are disposed on the left and right sides of the fixing roller 44. The fixing roller 44 is rotatably supported by side plates 34a and 34b via left and right bearings 46a and 46b. The side plates 34a and 34b are made of metal, support holes 53a and 53b for supporting the bearings 46a and 46b, bent portions 36a and 36b formed toward the outside of the fixing device 30, and an inward direction. Bending portions 35a and 35b formed in the above manner. The bent portions 35 and 36 have a positioning portion with the case member 32 and are fixed to the case member 32 by screws 41a and 41b.

  The case member 32 is made of a heat-resistant resin, and houses main parts of the fixing device 30 such as the fixing roller 44 and the pressure roller 45. As shown in FIGS. 1 and 3, the case member 32 is covered with a cover member 65 in a state where the main part of the fixing device 30 is accommodated.

  The cover member 65 is formed of a heat resistant resin, like the case member 32. As shown in FIG. 4, the cover member 65 includes pressing portions 31 a and 31 b that press the left and right end portions of the thin plate 62 as a supporting portion provided in the static eliminating brush 61 as the static eliminating member, and the pressing portions 31 a and 31 b. Supporting portion mounting openings 66 a and 66 b that guide the static elimination brush 61 to the heel, and a member 38 with a sticking (tempering) of the static elimination brush 61. The pressing portions 31 a and 31 b may be formed integrally with the cover member 65, or may be formed separately from the cover member 65.

  Further, as shown in FIG. 1, the sticking member 38 is disposed on the lower surface side of the recording medium 15 discharged from the nip portion N so as to have a predetermined angle with respect to the conveyance direction of the recording medium 15. The As a result, the tip of the linear body 63 of the static elimination brush 61 contacts the recording medium 15 at a predetermined angle, and therefore the time during which the linear body 63 is elastically deformed and is in contact with the recording medium 15. As a result, the recording medium 15 can be reliably discharged.

The support attachment openings 66 a and 66 b are disposed on both sides of the sticking member 38. As shown in FIG. 6, the pressing portions 31a and 31b are formed so as to straddle the support portion mounting openings 66a and 66b and bend portions 35a and 35b formed on the side plates 34a and 34b. It is arrange | positioned in the position facing. The width d ₁ of the pressing portions 31a and 31b is formed to be narrower than the width d ₂ of the support portion mounting openings 66a and 66b.

  Further, the pressing portions 31a and 31b may have a form as shown in FIG. In other words, the pressing portions 31a and 31b do not necessarily need to be formed so as to straddle the support portion mounting openings 66a and 66b, and may be present within a range where at least the thin plate 62 can be pressed.

  Here, as shown in FIG. 5, the static elimination brush 61 includes an aluminum thin plate 62, a stainless steel fiber linear body 63, and a conductive double-sided adhesive tape 64, and the thin plate 62 has a plurality of linear bodies 63. Is fixed by a conductive double-sided adhesive tape 64. As shown in FIG. 4, the thin plate 62 is fixed to the sticking member 38 of the cover member 65 by a conductive double-sided adhesive tape 64. Further, both ends of the thin plate 62 are arranged so as to enter inside from the support portion mounting openings 66 a and 66 b of the cover member 65. Further, as shown in FIGS. 1, 3, and 4, the cover member 65 is fixed to the bent portions 36a and 36b provided on the side plates 34a and 34b by screws 42a and 42b. At this time, both end portions of the thin plate 62 are sandwiched and held between the bent portions 35a and 35b provided on the side plates 34a and 34b and the pressing portions 31a and 31b of the cover member 65. Here, as shown in FIG. 4, the both ends of the thin plate 62 refer to regions having a predetermined length inside the both ends of the thin plate 62 where the linear body 63 is not provided, and the length is the bent portion 35a. And 35b and the press part 31a and 31b should just be sufficient length so that it may be pinched | interposed.

  The fixing device 30 configured as described above is fixed to a predetermined position of the image forming apparatus 10 by lock levers 43a and 43b. At this time, the side plates 34 a and 34 b of the fixing device 30 are in elastic contact with the conduction spring 52 provided in the image forming apparatus 10. The conduction spring 52 is electrically connected to a metal frame (not shown) included in the image forming apparatus 10. As a result, the static elimination brush 61 is electrically grounded to the metal frame of the image forming apparatus 10 that is a grounding member via the side plates 34a and 34b, the conduction spring 52, and the like.

  Next, the operation of the image forming apparatus 10 having the above configuration will be described.

  First, the recording medium 15 deposited and accommodated in the paper feed cassette 18 is separated and fed out one by one by the paper feed rollers 21a and 21b and the separation roller 22, and is transported by the transport rollers 23a and 23b. 14.

  On the other hand, the surfaces of the photosensitive drums 12Bk, 12Y, 12M, and 12C charged by a charging device (not shown) are exposed by the exposure devices 16Bk, 16Y, 16M, and 16C to form an electrostatic latent image. The electrostatic latent image is developed by a developing device (not shown), and toner images of four colors of black, yellow, magenta, and cyan are used as developer images on the surfaces of the photosensitive drums 12Bk, 12Y, 12M, and 12C. Is formed.

  Subsequently, when the recording medium 15 passes between the photosensitive drums 12Bk, 12Y, 12M, and 12C and the transfer rollers 13Bk, 13Y, 13M, and 13C as the conveyance belt 14 travels, black, yellow, The magenta and cyan toner images are sequentially transferred to form a color toner image on the recording medium 15. The toner remaining on the photoconductor drums 12Bk, 12Y, 12M, and 12C after the transfer is removed by a photoconductor cleaning device (not shown).

  The recording medium 15 onto which the toner image has been transferred is then conveyed to the fixing device 30. The fixing device 30 fixes the unfixed toner image T to form a color image.

  The recording medium 15 on which the toner image is fixed is transported by the discharge roller 24 and then discharged onto the upper cover 17 by the discharge transport roller 25 and stacked.

  Next, the operation of the fixing device 30 having the above configuration will be described.

  First, in the fixing device 30, the rotation of the fixing roller 44 is started with the start of printing in the image forming apparatus 10. In this case, the fixing roller gear 67 attached to one end of the fixing roller 44 receives a driving force from a fixing device driving gear (not shown) disposed in the main body of the image forming apparatus 10 and conveys the recording medium 15. Rotated in the direction. The pressure roller 45 is driven to rotate as the fixing roller 44 rotates.

  The halogen heater 51 generates heat when supplied with a current from a power supply circuit (not shown), and heats the fixing roller 44 from the inside. Then, the surface temperature of the heated fixing roller 44 is detected by a thermistor (not shown) and input to a temperature control circuit of a controller (not shown). The temperature control circuit controls the supply of current from the power supply circuit to the halogen heater 51 based on the detected surface temperature of the fixing roller 44, and maintains the surface temperature of the fixing roller 44 at the fixing temperature. The unfixed toner image T is heated by sandwiching the recording medium 15 at the nip portion N while the surface temperature of the fixing roller 44 is maintained at the fixing temperature, and is pressurized by the pressure roller 45 with a predetermined pressure. Then, the toner image is fixed on the recording medium 15.

  By the way, since a fluororesin layer as a release layer is formed on the outer peripheral surfaces of the fixing roller 44 and the pressure roller 45, the recording medium 15 is caused by conveyance friction when the recording medium 15 passes through the nip portion N. 15 is easily charged. However, the fixing device 30 includes a static elimination brush 61, and the linear body 63 of the static elimination brush 61 is predetermined on the lower surface side of the recording medium 15 discharged from the nip portion N with respect to the conveyance direction of the recording medium 15. It is arrange | positioned so that it may have an angle of. Therefore, the recording medium 15 on which the toner image is fixed by passing through the nip portion N is discharged while being in contact with the front end portion of the linear body 63 of the static elimination brush 61. Since the static elimination brush 61 is grounded via the side plates 34a and 34b, the conduction spring 52, etc., the electric charge charged on the recording medium 15 is removed by the contact of the tip of the linear body 63.

  As described above, in the present embodiment, the both ends of the thin plate 62 of the static elimination brush 61 are pressed and held by the cover member 65 in a state where both ends of the thin plate 62 are adhered to the side plates 34a and 34b as frame members. Even when the temperature of 34b reaches a high temperature, the static elimination brush 61 is not peeled off from the grounded side plates 34a and 34b, and a conduction failure does not occur. Accordingly, the charge removal of the recording medium 15 can be performed stably, and it is possible to prevent the occurrence of a conveyance failure such as a stack failure.

  Next, a second embodiment of the present invention will be described. In addition, about what has the same structure as 1st Embodiment, the description is abbreviate | omitted by providing the same code | symbol. The description of the same operations and effects as those of the first embodiment is also omitted.

  FIG. 8 is a cross-sectional view of the main part of the fixing device according to the second embodiment of the present invention. FIG. 9 is a cross-sectional view taken along the line ZZ in FIG. FIG. 10 is an exploded perspective view of the fixing device according to the second embodiment of the present invention as viewed from the recording medium discharge direction, and FIG. 11 is a perspective view of the second embodiment of the present invention. It is sectional drawing of a static elimination brush.

  As shown in FIGS. 8 and 10, the fixing roller 44 and the pressure roller 45 are disposed on the frame member 71. The frame member 71 has side plates 34a and 34b and a bent bottom surface portion 39 formed so as to connect between the left and right side plates 34a and 34b. Further, a wall portion 54 extending substantially vertically upward is connected to an end portion of the bent bottom surface portion 39, and a bent portion 37 having a predetermined angle with the wall portion 54 is connected to the upper end of the wall portion 54. Is formed. The frame member 71 is made of metal.

  The cover member 65 includes a pressing portion 69 that presses the static eliminating brush 61 formed at a position facing the bending portion 37 of the frame member 71. And the thin plate 62 as a brush support part of the static elimination brush 61 is pinched | interposed and hold | maintained by the said bending part 37 and the press part 69. FIG. As shown in FIG. 8, the bending portion 37 and the pressing portion 69 have a predetermined angle with respect to the conveyance direction of the recording medium 15 on the lower surface side of the recording medium 15 discharged from the nip portion N. It is arranged. As a result, the tip of the linear body 63 of the static elimination brush 61 contacts the recording medium 15 at a predetermined angle, and therefore the time during which the linear body 63 is elastically deformed and is in contact with the recording medium 15. As a result, the charge of the recording medium 15 can be reliably removed.

  Here, as shown in FIG. 11, the static elimination brush 61 includes an aluminum thin plate 62 and a stainless fiber linear body 63, and the plurality of linear bodies 63 are sandwiched by the thin plates 62. It is fixed. In this case, the linear body 63 is fixed to the thin plate 62 with an adhesive (thermosetting adhesive, double-sided adhesive tape, etc.) not shown.

  As shown in FIGS. 8 to 10, the cover member 65 includes bent portions 36 a and 36 b provided on the side plates 34 a and 34 b of the frame member 71 by screws 42 a and 42 b, as in the first embodiment. Fixed to. At this time, the thin plate 62 is sandwiched and held between the bent portion 37 of the frame member 71 and the pressing portion 69 of the cover member 65.

  Thus, since the thin plate 62 as the support portion of the static elimination brush 61 is sandwiched and held between the bent portion 37 of the frame member 71 and the pressing portion 69 of the cover member 65, it is necessary to use a double-sided adhesive tape. Absent. Therefore, even when the fixing device 30 is in a high temperature state, the neutralization brush 61 can be more reliably conducted.

  Since the configuration and operation of other points are the same as those in the first embodiment, description thereof is omitted.

  Thus, in the present embodiment, the thin plate 62 of the static elimination brush 61 is pressed and held by the frame member 71 and the cover member 65 without using a double-sided adhesive tape. Therefore, even if the frame member 71 is in a high temperature state due to the fixing operation, no conduction failure occurs. Therefore, it is possible to more stably remove static electricity from the recording medium 15 than in the first embodiment, and it is possible to prevent the occurrence of a conveyance failure such as a stack failure.

  Next, a third embodiment of the present invention will be described.

  In the first and second embodiments, no particular mention is made of the static elimination action and the static elimination effect from the viewpoint of the length of the static elimination brush. However, conventionally, when the static elimination brush is long, damage such as bending (bending) or falling (hereinafter referred to as “bending”) of the linear body tends to occur as the number of printed sheets increases. In addition, when the static eliminating brush is short, the tip of the linear body may not be able to contact the recording medium. In either case, the contact between the static eliminating brush and the recording medium becomes unstable, and there is a problem that a sufficient static eliminating effect cannot be obtained. The present embodiment eliminates the problems in the conventional fixing device, and provides a fixing device that stably brings a recording medium and a linear body into contact with each other to provide a static elimination effect, and an image forming apparatus including the fixing device. A further purpose is to provide.

  In addition, about the thing which has the same structure as 1st and 2nd embodiment, the description is abbreviate | omitted by providing the same code | symbol. The description of the same operations and effects as those of the first and second embodiments is also omitted.

  12 is a perspective view of the fixing device according to the third embodiment of the present invention, FIG. 13 is an exploded perspective view of the fixing device according to the third embodiment of the present invention, and FIG. 14 is a third embodiment of the present invention. FIG. 15 is a cross-sectional view of the main part of the fixing device in the embodiment, a cross-sectional view taken along the line ZZ in FIG. 12, and FIG. 15 is a cross-sectional view of the main part of the fixing device in the third embodiment of the present invention.

  As shown in FIGS. 12 and 13, the cover member 701 of the fixing device 700 according to the present embodiment has pressing portions 31 a and 31 b that press left and right ends of a thin plate 702 a of a neutralizing brush 702 as a neutralizing member described later. And supporting portion mounting openings 66a and 66b for guiding the static elimination brush 702 to the pressing portions 31a and 31b, and an attaching member 701a as an inclined portion for attaching the static elimination brush 702 in an inclined state. A horizontal portion 701b extending horizontally to the pressure roller 45 is formed at the upper end of the sticking member 701a. The cover member 701 is made of a heat resistant resin.

  As shown in FIG. 15, the surface area formed by connecting the nip portion N where the fixing roller 44 and the pressure roller 45 are pressed against each other and the nip portion of the discharge roller 24 is referred to as an ideal medium conveyance surface I. The ideal medium transport surface I is an ideal transport surface when the recording medium 15 is transported in a state where the recording medium 15 is not subjected to the resistance of the static eliminating brush 702 and is not loosened. Actually, the recording medium 15 is conveyed in a space having a certain extent including the ideal medium conveying surface I.

  The affixing member 701 a is disposed below the ideal medium conveyance surface I and is inclined toward the fixing roller 44. Here, an angle formed by the inclination direction of the sticking member 701a and the ideal medium conveyance surface I is defined as θ. In the present embodiment, the sticking member 701a is integrally formed with the cover member 701 by heat-resistant resin, but may be formed separately from the cover member 701. When the sticking member 701 a is formed separately from the cover member 701, it is desirable that the sticking member 701 a be formed of a resin material having a thermal expansion coefficient equivalent to that of the cover member 701.

  As shown in FIGS. 12, 13, and 15, the adhesive member 701 a and the horizontal portion 701 b have a plurality of guide rib members 701 c at predetermined intervals in a direction C that intersects the conveyance direction of the recording medium 15. It is integrally formed. As shown in FIG. 15, the guide rib member 701 c is disposed so as to protrude toward the pressure roller 45 at a position lower than the ideal medium conveyance surface I. Specifically, in the present embodiment, the guide rib member 701c is formed at twelve locations with a predetermined interval in the transverse direction C, and the gap (gap) distance between the tip of the guide rib member 701c and the pressure roller 45. Is 2 [mm]. Accordingly, the guide rib member 701c functions to stably guide the conveyance of the recording medium 15 while preventing the recording medium 15 from being wound around the pressure roller 45.

  In addition, the guide rib member 701c can also be comprised separately. In that case, the guide rib member 701c is desirably formed of a resin material having a thermal expansion coefficient equivalent to that of the cover member 701. When the guide rib member 701c is formed of a material different from that of the cover member 701, it is desirable to use a fluorine-based resin that is excellent in toner releasability.

  Furthermore, the arrangement interval of the guide rib members 701c is set such that, for example, when a recording medium 15 having a prescribed size such as A4 size paper, B5 size paper, A6 size paper, or a postcard is conveyed, the width direction (transverse direction) of the recording medium 15 The end portion in the same direction as C) is adjusted so as not to be caught by the guide rib member 701c. For example, in FIG. 12 and FIG. 13, three sets are provided with four guide rib members 701c arranged at a predetermined interval as one set, and the interval between the three sets is wider than the predetermined interval. Yes. By disposing the guide rib member 701c in this way, it is possible to prevent a jam from occurring when the recording medium 15 is discharged. However, the arrangement intervals and the number of arrangements shown in the drawing are merely examples, and can be changed according to the fixing device 700 as long as the jam does not occur when the recording medium 15 is discharged.

  Next, the structure of the static elimination brush 702 in this Embodiment is demonstrated in detail.

  FIG. 16 is a sectional view of a static elimination brush according to the third embodiment of the present invention, and FIG. 17 is a front view of the static elimination brush according to the third embodiment of the present invention.

  As shown in FIG. 16, a static elimination brush 702 as a static elimination member includes a thin plate 702a as an aluminum support, a linear body 702b made of stainless fiber, and a conductive double-sided adhesive tape 702c. The length L1 is exposed from the thin plate 702a. One adhesive surface of the conductive double-sided adhesive tape 702c serves to fix a predetermined region of the base portion of the linear body 702b to the thin plate 702a, and the other adhesive surface of the conductive double-sided adhesive tape 702c is attached with the neutralizing brush 702. It acts to affix to the member 701a. As shown in FIG. 17, the linear body 702 b is disposed with a predetermined pitch interval S when viewed from the downstream side in the conveyance direction of the recording medium 15. The portion where the linear body 702b is opened wider than the predetermined pitch interval S is an area prepared for the guide rib member 701c to be disposed, whereby the neutralizing brush 702 is pasted on the pasting member 701a. In this case, the linear body 702b can be prevented from interfering with the guide rib member 701c. However, this is only an example, and the number of linear bodies 702b and the pitch interval S can be changed according to the fixing device 700 as long as the effects of the present embodiment can be appropriately achieved.

  The linear body 702b of the static eliminating brush 702 according to the present exemplary embodiment is, for example, a bundle of 80 metal fine wires having a diameter of 12 [μm] made of stainless steel fibers to form one linear body. Thus, a total of 31 pieces are arranged at a pitch of 6.4 [mm] in the width 224 [mm] in the transverse direction of the ideal medium transport surface I.

  Note that the linear body 702b adds and kneads copper ions, carbon black, carbon fibers, and the like to resin fibers (for example, acrylic resin fibers, nylon resin fibers, etc.) having heat resistance in addition to the metal fine wires. You may use what gave electroconductivity by this.

  As shown in FIG. 13 and FIG. 14, the linear body 702b of the static elimination brush 702 is attached by attaching the proximal end region of the static elimination brush 702 to the adhesive member 701a with the conductive double-sided adhesive tape 702c. An angle extending toward the fixing roller 44 along the inclination angle θ of the member 701a, and the angle formed by the linear body 702b with the ideal medium conveyance surface I is substantially equal to the inclination angle θ.

  Further, as shown in FIG. 12, the thin plate 702a of the static elimination brush 702 is fixed to the sticking member 701a at a position lower than the guide rib member 701c. Thereby, the base end part area | region of the static elimination brush 702 can be appropriately fixed to the sticking member 701a, without interfering with the guide rib member 701c.

  Further, both end portions of the thin plate 702a are arranged so as to enter inward from the support portion mounting openings 66a and 66b of the cover member 701 as in the first embodiment, and bent portions provided on the side plates 34a and 34b. It is sandwiched between 35a and 35b and the pressing portions 31a and 31b of the cover member 701 and is pressed and held. Here, both end portions of the thin plate 702a refer to regions having a predetermined length from both ends of the thin plate 702a where the linear body 702b is not provided, and the lengths thereof are the bent portions 35a and 35b and the pressing portions 31a and 31b. It is sufficient that the length is sufficient to be sandwiched between the two.

  The fixing device 700 configured as described above is fixed to a predetermined position of the image forming apparatus 10 by the lock levers 43a and 43b, and the side plates 34a and 34b are elastically connected to the conduction spring 52 provided in the image forming apparatus 10. The conductive spring 52 is electrically connected to the metal frame of the image forming apparatus 10. As a result, the static elimination brush 702 is electrically grounded to the metal frame of the image forming apparatus 10 that is a grounding member via the side plates 34a and 34b, the conduction spring 52, and the like.

  In the present embodiment, as shown in FIG. 15, the length L3 of the portion facing the sticking member 701a in the linear body 702b exposed from the thin plate 702a is set to 4 [mm], and the sticking member 701a. The length L4 of the horizontal portion 701b extending horizontally with respect to the pressure roller 45 is 6 [mm], and the distance L5 from the nip portion N to the linear body 702b is 12 [mm]. An angle θ2 formed by 701a and the horizontal portion 701b is 135 degrees.

  Next, the operation of the fixing device 700 in the present embodiment will be described.

  FIG. 18 is a diagram showing an image pattern used in the evaluation test of the fixing device according to the third embodiment of the present invention, and FIG. 19 shows the occurrence of electrostatic offset of the fixing device according to the third embodiment of the present invention. FIG. 20 is a scatter diagram showing the relationship between the number of linear body damage and the length of the linear body of the fixing device according to the third embodiment of the present invention.

  The recording medium 15 having the transferred toner image T passes through the nip portion N of the fixing roller 44 and the pressure roller 45, whereby the toner image T is fixed. At this time, charges are accumulated on the recording medium 15 due to conveyance friction received from the fixing roller 44 and the pressure roller 45 when passing through the nip portion N.

  Subsequently, the recording medium 15 travels in the vicinity of the ideal medium conveyance surface I, and is discharged from the fixing device 700 while being in contact with the tip of the static elimination brush 702. At this time, since the static elimination brush 702 is grounded via the side plates 34 a and 34 b and the conduction spring 52, the charge charged on the recording medium 15 is removed by the fixing roller 44 and the pressure roller 45.

  Here, the angle formed by the linear body 702b with the ideal medium conveyance surface I is θ, the length of the portion protruding from the thin plate 702a in the linear body 702b is L1, and the ideal medium conveyance surface in the portion protruding from the thin plate 702a. The length up to the portion intersecting with I is defined as L2, and the conveyance speed of the recording medium 15 is defined as V. Then, as described below, the angle θ, the lengths L1 and L2, and the conveyance speed V were used as parameters to perform an evaluation test for damage to the linear body 702b caused by contact of the recording medium 15. This is because that the linear body 702b is not damaged is a condition for stably performing the charge eliminating action on the recording medium 15. In the meantime, in the sense that the linear body 702b protrudes from the ideal medium transport surface I, (L1-L2) is hereinafter referred to as a linear body protruding length.

In this evaluation test, the image forming apparatus 10 is used, in which the conveyance speed V of the recording medium 15 is 93 [mm / sec], and A4 size paper as the recording medium 15 is passed in the vertical direction at a speed of 16 [ppm]. did. The recording medium 15 used in this evaluation test is P paper A4 size manufactured by Fuji Xerox Co., Ltd., and weighed 75 [g / m ² ]. In order to easily charge the recording medium 15 and observe the effect of charge removal, the recording medium 15 left for 24 hours in a low temperature and low humidity environment with a temperature of 10 ° C. and a relative humidity of 20% was used.

  In this evaluation test, the image pattern shown in FIG. 18 was used. In consideration of the fact that electrostatic offset is a particularly noticeable phenomenon in a halftone image, in this evaluation test, a pattern (hereinafter referred to as a toner-free area) that defines toner-free and toner-free areas in units of 2 dots in length and width (4 dots in total) is used. 2 × 2 pattern) was used as the image pattern.

  The table shown in FIG. 19 shows the results of evaluating the occurrence of electrostatic offset when a 2 × 2 pattern image is output with different numbers of sheet passing histories and linear body protrusion lengths (L1-L2). is there. Here, the electrostatic offset means that a part of the toner incompletely fixed on the recording medium 15 is attracted to an electric field generated by frictional charging between the fixing roller 44 and the recording medium 15 and moves onto the fixing roller 44. This is a phenomenon in which after the fixing roller 44 makes one rotation, it is transferred and fixed on the recording medium 15 again to deteriorate the image quality.

  The evaluation of the charge removal performance of the linear body 702b was made by visually observing the presence or absence of streaks generated on the 2 × 2 pattern print image printed on the recording medium 15, and was classified into three levels. In other words, a good level (represented by a circle in the table) that seems to have suppressed electrostatic offset without streaking in the printed image, and a slight streak in the printed image was seen overall. There are three levels: an acceptable level in each case (indicated by Δ in the table) and a level in which a density difference can be clearly seen (indicated by × in the table).

  According to the table shown in FIG. 19, when the linear protrusion length (L1-L2) is 2 [mm] or more, no streak is observed in the printed image regardless of the number of printed sheets, and the electrostatic offset is reduced. It was a good level (○ in the table) that is considered to have been able to be suppressed. On the other hand, even with the static eliminating brush 702 when 500 sheets were passed, a slight streak was observed when the linear protrusion length (L1-L2) was 0 [mm]. Further, in the case where the number of printed sheets is 60000 and the paper passing history is long, when the linear protrusion length (L1-L2) is shorter than 2 [mm], a density difference is clearly seen (× in the table). It was confirmed that the effect of static elimination was low. When the linear protrusion length (L1-L2) is shorter than 2 [mm], the tip of the static elimination brush 702 frays and expands due to repeated contact with the recording medium 15, and further wears away. This is considered to be because the amount of contact between the brush 702 and the recording medium 15 becomes small. From the above evaluation results, it was derived that the occurrence of electrostatic offset can be effectively suppressed when the linear body protrusion length (L1-L2) is 2 [mm] or more.

  FIG. 20 shows the relationship between the length of the linear body 702b protruding from the ideal medium conveyance surface I and the number of damages of the static elimination brush 702. In FIG. 20, the linear body protrusion length (L1-L2) is fixed to 3 [mm], and the length of the linear body 702b protruding from the thin plate 702a to the portion intersecting with the ideal medium conveyance surface I is shown. This shows the result of measuring the number of the linear bodies 702b that are damaged such as bending when L2 is variable and up to 1000 sheets are passed.

  As shown in the drawing, when (L1−L2) −L2 <0 [mm], the number of damages of the linear body 702b is equal to zero. This is because the linear body 702b tends to bend gently as the value of (L1-L2) -L2 decreases, and the bending stress generated in the linear body 702b decreases. On the other hand, when the value of (L1-L2) -L2 is 0 [mm] or more, the linear body 702b bends suddenly, the bending stress generated in the linear body 702b increases, and the linear body 702b is easily bent. Conceivable.

  The results shown in FIG. 20 are obtained when the linear body protrusion length (L1-L2) is fixed to 3 [mm], but 2 [mm] ≦ (L1-L2) ≦ 5 [mm. ], The same results could be obtained.

From the above consideration, the range in which the occurrence of electrostatic offset can be suppressed without causing damage such as bending of the linear body 702b is defined as the following formulas (1) and (2).
2 [mm] ≦ (L1-L2) ≦ 5 [mm] (1)
(L1-L2) -L2 <0 Formula (2)
Next, a range in which the angle θ of the linear body 702b contributes to the static elimination action is examined.

  FIG. 21 is a scatter diagram showing the relationship between the number of damaged linear bodies and the number of printed sheets for each inclination angle of the static eliminating brush of the fixing device according to the third embodiment of the present invention.

  Here, the linear body protrusion length (L1-L2) is set to 3 [mm], and the length L2 to the portion intersecting with the ideal medium conveyance surface I in the portion protruding from the thin plate 702a in the linear body 702b is 7 The evaluation test was performed as [mm], that is, (L1-L2) −L2 = −4 [mm] <0 [mm]. FIG. 21 shows the result of measuring the relationship between the number of printed sheets and the number of damaged linear objects for each angle θ formed by the static elimination brush 702 and the ideal medium conveyance surface I.

  When the angle θ of the static elimination brush 702 is 30 degrees, when the number of printed sheets is small (for example, 20000), the linear body 702b easily returns to the original position due to its elastic force and is a line that bends in the direction of the pressure roller 45. The number of the state bodies 702b is as small as five, and the influence on the static elimination action is relatively small. However, when the number of printed sheets reaches 80000, the number of linear bodies 702b that bend in the direction of the pressure roller 45 exceeds 20, and all the linear bodies 702b of the static elimination brush 702, that is, 31 linear bodies. Since the number of linear bodies 702b that abut on the recording medium 15 is reduced as compared to the case where 702b abuts normally without being bent, the static elimination effect becomes extremely small.

  Similarly, even when the angle θ of the static elimination brush 702 is 105 degrees, as the number of printed sheets increases, the number of the linear bodies 702b that bend downstream in the conveyance direction of the recording medium 15 increases, and the line that contacts the recording medium 15 Since the number of the state bodies 702b decreases, the static elimination effect becomes extremely small.

  On the other hand, if the angle θ of the static elimination brush 702 is in the range of 45 to 90 degrees, the linear body 702b is bent at most four, and almost all the linear bodies 702b come into contact with the recording medium 15 to eliminate static electricity. Since it contributes to the action, there is almost no reduction in the static elimination effect. Actually, a high-quality print image could be obtained on the recording medium 15.

  Further, the angle θ of the static elimination brush 702 affects the conveyance speed V of the recording medium 15. The results shown in FIG. 21 are obtained when the transport speed V is 93 [mm / sec] (16 [ppm] when the A4 size paper is moved vertically), but V ≦ 174 [mm / sec] (30 [ppm] or less in the paper feed with the A4 size paper in the vertical direction) in the range, a similar result could be obtained.

  From the above consideration, it was derived that the range of the angle θ that the static elimination brush 702 contributes to the static elimination action is 45 ° ≦ θ ≦ 90 ° under the condition of V ≦ 174 [mm / sec].

As described above, in this embodiment, in addition to the effects of the first embodiment, when the following expressions (1) to (4) are satisfied, the linear body 702b is almost damaged such as bending. In addition, the occurrence of electrostatic offset can be suppressed, and damage such as bending of the linear body 702b can be suppressed, so that the charge removal effect can be enhanced, and a high-quality printed image can be obtained on the recording medium 15. .
2 [mm] ≦ (L1-L2) ≦ 5 [mm] (1)
(L1-L2) -L2 <0 Formula (2)
45 degrees ≦ θ ≦ 90 degrees (3)
V ≦ 174 [mm / sec] (4)
However, the protruding length of the linear body is (L1-L2), the length of the portion protruding from the thin plate 702a in the linear body 702b is L2, and the angle of the neutralizing brush 702 is the length to the portion intersecting the ideal medium conveyance surface I. θ, the conveyance speed of the recording medium 15 is V.

  Next, a fourth embodiment of the present invention will be described.

  In the present embodiment, the fixing roller and the pressure roller are mainly increased in diameter, the pressure roller is a hollow roller corresponding to double-sided printing, a halogen heater is used as a heat source, and a static elimination brush is provided. It differs from the third embodiment in that it is provided on the separation member of the recording medium. Therefore, the case member has the same configuration as that of the third embodiment except that the case member is different in size and requires an attachment member for attaching the separation member to the case member.

  Therefore, about the thing which has the same structure as 1st-3rd embodiment, the description is abbreviate | omitted by providing the same code | symbol. The description of the same operations and effects as those of the first to third embodiments is also omitted.

  In FIG. 2 described in the first embodiment, the constituent members corresponding to double-sided printing are not particularly described. However, after printing one side of the recording medium, the recording medium is reversed and the image is again displayed. Since the configuration for transporting the recording medium accompanying double-sided printing in which the toner image is transferred to and fixed on the back surface by being transported to the forming unit is a known technique, description thereof is omitted.

  FIG. 22 is a perspective view of the main part of the fixing device according to the fourth embodiment of the present invention, and FIG. 23 is a side view of the main part of the fixing device according to the fourth embodiment of the present invention.

  As shown in the drawing, the fixing device 800 in this embodiment includes a fixing roller 811 and a pressure roller 812, and a nip portion N for fixing an unfixed toner image on the recording medium 15 is the fixing roller 811. On the other hand, it is formed by pressing the pressure roller 812 with a pressure means (not shown).

  The fixing roller 811 is, for example, a hollow roller having an outer diameter of 36 [mm] and an aluminum cored bar having a thickness of 1.5 [mm] having a thickness of about 1.5 [mm] made of silicone rubber. A heat-resistant elastic layer is formed, and a fluororesin layer having a thickness of about 30 [μm] as a release layer is formed on the outer peripheral surface thereof. In the present embodiment, the core metal is described as being made of aluminum, but it is not necessarily made of aluminum, and other metals such as iron may be used. In addition, a halogen heater (not shown) as a heat source is disposed inside the fixing roller 811.

  The pressure roller 812 is, for example, a hollow roller having an outer diameter of 36 [mm], and a thickness of about 1.5 [mm] made of silicone rubber on the outer peripheral surface of an aluminum cored bar having a thickness of 1.5 [mm]. And a fluororesin layer having a thickness of about 30 [μm] as a release layer is formed on the outer peripheral surface. Further, a halogen heater as a heat source (not shown) is also provided inside the pressure roller 812.

  In the present embodiment, since the fixing roller 811 and the pressure roller 812 are larger in diameter than the fixing roller 44 and the pressure roller 45 in the first to third embodiments, faster fixing is performed. Operation is possible.

  Further, the fixing roller 811 and the pressure roller 812 are disposed on an attachment member 813 for attaching to a case member (not shown). The mounting member 813 includes side wall portions 814a and 814b made of a conductive material, and a separation plate 820 as a separating means made of a conductive material fixed between the side wall portions 814a and 814b. As will be described later, the separation plate 820 is provided to separate the recording medium 15 that is stuck to the pressure roller 812 having a small curvature and becomes difficult to separate.

  As shown in FIG. 23, separation plate 820 in the present embodiment is a steel plate having a thickness of 1 [mm] bent into an L shape (hereinafter referred to as “L-shaped bending plate”). . The separation plate 820 includes a separation unit 820 a disposed at a position facing the recording medium 15, and an inclined unit 820 b inclined toward the fixing roller 811 with a predetermined angle θ with respect to the ideal medium conveyance surface I. ing. A stainless steel plate portion 820c as a stainless steel plate having a thickness of 0.3 mm is joined to the surface of the separation portion 820a on the ideal medium conveyance surface I side by spot welding, and is attached to the surface of the stainless steel plate portion 820c. Has a fluororesin layer having a thickness of 20 [μm] for toner release. The stainless steel plate portion 820c is disposed so that the gap distance between its tip and the pressure roller 812 is 1 [mm].

  On the side of the separation plate 820 facing the ideal medium conveyance surface I, a static elimination brush 702 is attached by a conductive double-sided adhesive tape 702c, and the linear body 702b extends along the inclination of the inclined portion 820b of the separation plate 820. It extends and protrudes on the ideal medium transport surface I of the recording medium 15.

  The neutralizing brush 702 is electrically grounded through the separation plate 820 and the side wall portions 814a and 814b to the metal frame of the image forming apparatus 10 that is a grounding member, as in the other embodiments.

  As shown in the figure, in the present embodiment, the length L3 of the portion where the linear body 702b protruding from the thin plate 702a is in contact with the inclined portion 820b is 6 mm, and the stainless steel is removed from the linear body 702b. The length L4 to the tip of the plate-making part 820c is 15 [mm], the distance L5 from the downstream end of the nip part N to the linear body 702b is 26 [mm], the separating part 820a and the inclined part 820b Was made 90 degrees.

  Next, the operation of the fixing device 800 in the present embodiment will be described.

  FIG. 24 is a diagram showing the relationship between the number of prints of the recording medium and the number of damaged linear bodies for each inclination angle of the static eliminating brush according to the fourth embodiment of the present invention.

  In the present embodiment, the fixing roller 811 and the pressure roller 812 are larger in diameter than the fixing roller 44 and the pressure roller 45 in the first to third embodiments. As a result, the nip amount of the recording medium 15 with respect to the pressure roller 812 is increased. In the case of duplex printing, since the toner image is also formed on the surface of the recording medium 15 that contacts the pressure roller 812, the recording medium 15 that has passed through the nip portion N tends to stick to the pressure roller 812. In other words, the larger the diameter of the pressure roller 812, the smaller the curvature of its peripheral surface, and it becomes difficult for the recording medium 15 to separate from the pressure roller 812 by itself. Therefore, the stainless steel plate portion 820c of the separation plate 820 has a gap distance of 1 mm from the pressure roller 812 as described above, so that the gap between the tip of the recording medium 15 and the pressure roller 812 is between. The recording medium 15 can be separated from the pressure roller 812. The recording medium 15 separated from the pressure roller 812 is sequentially pushed downstream. After that, the point that the recording medium 15 is neutralized by coming into contact with the neutralizing brush 702 is the same as in the description of the third embodiment.

  In the evaluation test in the present embodiment, the image forming is performed such that the conveyance speed V of the recording medium 15 is 231 [mm / sec], and the A4 size paper as the recording medium 15 is passed in the vertical direction at a speed of 40 [ppm]. Apparatus 10 was used. The recording medium 15 and the image pattern (2 × 2 pattern image) used for the evaluation test in the present embodiment are the same as those in the third embodiment.

Then, in the evaluation test in the present embodiment, the linear body protrusion lengths (L1-L2) and (L1-L2) -L2 except for the conveyance speed V of the recording medium 15 are used in the third embodiment. When the paper passing evaluation was performed under the same conditions as above, satisfactory evaluation results could be obtained when the following expressions (5) and (6) were satisfied.
2 [mm] ≦ (L1-L2) ≦ 5 [mm] (5)
(L1-L2) -L2 <0 Formula (6)
Next, a range in which the angle θ of the linear body 702b contributes to the static elimination action is examined.

  As shown in the figure, when the angle θ of the static elimination brush 702 is 30 degrees, bending in the direction of the stainless steel plate portion 820c occurs, and when the angle θ is 90 degrees and 105 degrees, bending in the discharge direction is performed. It has occurred. This is presumably due to the fact that the load on the static elimination brush 702 is increased because the recording medium 15 is discharged at a higher speed than in the third embodiment.

  Therefore, as a result of this evaluation test, if the angle θ of the static elimination brush 702 is in a range of 45 degrees ≦ θ ≦ 75 degrees, the static elimination brush 702 is bent in the direction of the pressure roller 812 and the recording medium 15 is conveyed. It can be said that it can contribute to the static elimination action by suppressing the occurrence of bending toward the downstream side.

  Further, the angle θ of the static elimination brush 702 affects the conveyance speed V of the recording medium 15. In the evaluation test according to the present embodiment, the conveyance speed V was set to 231 [mm / sec] (40 [ppm] in a paper feed in which the A4 size paper is oriented in the vertical direction), but 174 [mm / sec] <V ≦ Similar results could be obtained even in the range of 347 [mm / sec]. The transport speed V = 347 [mm / sec] is a speed of 60 [ppm] when the A4 size paper is fed in the vertical direction.

  From the above consideration, the range of the angle θ that the static eliminating brush 702 contributes to the static eliminating action is 45 degrees ≦ θ ≦ 75 degrees under the condition of 174 [mm / sec] <V ≦ 347 [mm / sec]. Was derived.

Thus, in this embodiment, when the following formulas (5) to (8) are satisfied, damage such as bending of the linear body 702b is suppressed, and high-quality printing is performed by preventing the occurrence of electrostatic offset. An image can be obtained, and the linear body 702b that contributes to the charge eliminating action is maintained by suppressing the bending of the linear body 702b in the direction of the pressure roller 812 and the downward bending of the recording medium 15 in the transport direction. As a result of the excellent static elimination effect, it is possible to effectively prevent the occurrence of a conveyance failure such as a stack failure of the recording medium 15.
2 [mm] ≦ (L1-L2) ≦ 5 [mm] (5)
(L1-L2) -L2 <0 Formula (6)
45 degrees ≦ θ ≦ 75 degrees (7)
174 [mm / sec] <V ≦ 347 [mm / sec] (8)
However, the protruding length of the linear body is (L1-L2), the length of the portion protruding from the thin plate 702a in the linear body 702b is L2, and the angle of the neutralizing brush 702 is the length to the portion intersecting the ideal medium conveyance surface I. θ, the conveyance speed of the recording medium 15 is V.

  Next, a fifth embodiment of the present invention will be described. In addition, about the thing which has the same structure as 1st-4th embodiment, the description is abbreviate | omitted by providing the same code | symbol. The description of the same operations and effects as those in the first to fourth embodiments is also omitted.

  FIG. 25 is a side view of the main part of the fixing device according to the fifth embodiment of the present invention.

  This embodiment is different from the fourth embodiment in that the separating means is mainly disposed on the fixing roller side.

  As shown in the figure, a separating member 830 as a separating means is spot-welded to an L-shaped bent plate 831 having a thickness of 1 [mm] and the side of the L-shaped bent plate 831 facing the ideal medium conveying surface I. And a stainless steel plate member 833 as a stainless steel plate having a thickness of 0.3 mm. The stainless steel plate member 833 is bent at a predetermined angle θ2 on the downstream side in the transport direction of the horizontal portion 833a and a horizontal portion 833a extending toward the fixing roller 811 substantially parallel to the transport direction of the recording medium 15. And an inclined portion 833b extending in a direction away from the ideal medium transport surface I. A fluororesin layer having a thickness of 20 [μm] is formed on the surface of the horizontal portion 833a for toner release. A neutralizing brush 702 is attached to the side of the inclined portion 833b facing the ideal medium conveyance surface I, and the linear body 702b extends along the inclination of the inclined portion 833b and protrudes from the ideal medium conveyance surface I. ing.

  The neutralizing brush 702 is electrically grounded to the metal frame of the image forming apparatus 10 that is a grounding member via the separating member 830, as in the other embodiments.

  In the evaluation test in the present embodiment, the conveyance speed V of the recording medium 15 is set to a range of 174 [mm / sec] <V ≦ 347 [mm / sec], and the A4 size paper as the recording medium 15 is set to 30 in the vertical direction. An image forming apparatus that passes paper at a rate of [ppm] to 60 [ppm] was used. The recording medium 15 and the image pattern (2 × 2 pattern image) used in the evaluation test in the present embodiment are the same as those in the fourth embodiment.

  In the present embodiment, the gap distance between the tip of the stainless steel plate member 833 and the fixing roller 811 is 0.5 mm, and the linear body 702b protruding from the thin plate 702a is in contact with the inclined portion 833b. The length L3 of the portion is 7 mm, the length L4 of the horizontal portion 833a is 13 mm, the distance L5 from the downstream end of the nip portion N to the linear body 702b is 20 mm, The angle θ2 formed by the horizontal portion 833a and the inclined portion 833b is 115 degrees.

  The operation of the fixing device 800 in the present embodiment is substantially the same as that of the fourth embodiment, and the stainless steel plate member 833 is used as the recording medium 15 in order to separate the recording medium 15 stuck to the fixing roller 811. The recording medium 15 is separated from the fixing roller 811 by being sandwiched between the leading end of the recording medium and the fixing roller 811. The recording medium 15 separated from the fixing roller 811 is sequentially pushed out to the downstream side, and is neutralized by coming into contact with the neutralizing brush 702 as in the description of the fourth embodiment.

Also in the present embodiment, similarly to the fourth embodiment, when the following formulas (5) to (8) are satisfied, damage such as bending of the linear body 702b is suppressed, and an electrostatic offset is generated. And a high-quality printed image can be obtained. In particular, in the present embodiment, static electricity is eliminated by directly contacting the printing surface of the recording medium 15, so that the occurrence of electrostatic offset during single-sided printing can be effectively suppressed. Further, the linear body 702b that contributes to the static elimination action is suppressed by suppressing the bending of the linear body 702b in the direction of the fixing roller 811 and the downward bending of the recording medium 15 in the conveyance direction, and an excellent static elimination effect. Therefore, it is possible to effectively prevent the occurrence of a conveyance failure such as a stack failure of the recording medium 15.
2 [mm] ≦ (L1-L2) ≦ 5 [mm] (5)
(L1-L2) -L2 <0 Formula (6)
45 degrees ≦ θ ≦ 75 degrees (7)
174 [mm / sec] <V ≦ 347 [mm / sec] (8)
However, the protruding length of the linear body is (L1-L2), the length of the portion protruding from the thin plate 702a in the linear body 702b is L2, and the angle of the neutralizing brush 702 is the length to the portion intersecting the ideal medium conveyance surface I. θ, the conveyance speed of the recording medium 15 is V.

  Next, a sixth embodiment of the present invention will be described. In addition, about the thing which has the same structure as 1st-5th embodiment, the description is abbreviate | omitted by providing the same code | symbol. The description of the same operations and effects as those in the first to fifth embodiments is also omitted.

  FIG. 26 is a side view of the main part of the fixing device according to the sixth embodiment of the present invention, and FIG. 27 is a front view of the main part of the fixing device according to the sixth embodiment of the present invention.

  This embodiment is different from the fifth embodiment mainly in that the separating members are disposed on the fixing roller side and the pressure roller side, respectively.

  As shown in the figure, the static elimination brush 702 includes an upper static elimination brush 702-upp disposed on the upper side and a lower static elimination brush 702-low disposed on the lower side. In order to prevent the upper static elimination brush 702-up and the lower static elimination brush 702-low from interfering with each other, the upper linear body 702b-upp of the upper static elimination brush 702-up and the lower static elimination brush 702-low The side linear bodies 702b-low are alternately arranged on the ideal medium transport surface I. Here, the symbol “upp” indicates the configuration on the fixing roller 811 side, and the symbol “low” indicates the configuration on the pressure roller 812 side.

  In the present embodiment, the length L3-low of the portion where the lower linear body 702b-low protruding from the lower thin plate 702a-low is in contact with the inclined portion 833b-low of the lower stainless steel plate member is 6 [Mm], the length L4-low of the lower horizontal portion 833a-low is 10 [mm], and from the downstream end of the nip portion N to the upper linear body 702b-upp and the lower linear body 702b-low The distances L5-upp and L5-low were set to 20 [mm]. Other configurations are the same as those in the fifth embodiment.

  The operation of the fixing device 900 in the present embodiment is substantially the same as the operation of the fixing device 800 in the fifth embodiment to separate the recording medium 15 that adheres to the fixing roller 811 and the pressure roller 812. In addition, a stainless steel plate member 833 is sandwiched between printing margins provided at the front end of the recording medium 15 to separate the recording medium 15 from the fixing roller 811 and the pressure roller 812. The recording medium 15 separated from the fixing roller 811 and the pressure roller 812 is sequentially pushed out to the downstream side, and the point where the recording medium 15 is discharged by contacting the upper discharging brush 702-upp and the lower discharging brush 702-low is described above. This is the same as the description in the fifth embodiment.

  Also in the present embodiment, as in the fourth embodiment, when the expressions (5) to (8) are satisfied, the upper linear body 702b-upp and the lower linear body 702b-low are bent. Damage is suppressed, and generation of electrostatic offset can be prevented, and a high-quality printed image can be obtained. In particular, in the present embodiment, since the upper static elimination brush 702-upp and the lower static elimination brush 702-low are in direct contact with the recording medium 15 for static elimination, not only during single-sided printing but also during duplex printing, Generation of electrostatic offset can be effectively suppressed. Further, the bending of the upper linear body 702b-upp and the lower linear body 702b-low in the direction of the fixing roller 811 and the pressure roller 812 and the bending of the recording medium 15 in the conveyance direction downstream side are suppressed, The upper linear body 702b-upp and the lower linear body 702b-low that contribute to the static elimination action are maintained, and an excellent static elimination effect is achieved. Therefore, it is possible to effectively prevent the occurrence of a conveyance failure such as a stack failure of the recording medium 15. Can do.

  In the fifth and sixth embodiments, the example in which the separating unit is disposed on the downstream side of the fixing roller and the pressure roller has been described. However, this is only an example, and in the case of single-sided printing. The separating means may be disposed on the upstream side of the pressure roller. However, when the separating means is disposed on the upstream side of the pressure roller, it is necessary to adjust the charge removal amount by interposing a resistance between the charge removal brush and the case member. This is because the toner that has not yet been fixed on the recording medium is held on the recording medium in a charged state, and if the charge is completely lost by the charge eliminating brush, the formed toner image is also lost. is there.

  Moreover, in the said 3rd Embodiment, the example which stuck the static elimination brush on the sticking member was demonstrated, In the said 4th-6th embodiment, the example which stuck the static elimination brush on the isolation | separation means was demonstrated. . However, the appropriate angle of the static eliminating brush does not depend on the target to which the static eliminating brush is applied, that is, whether V ≦ 174 [mm / sec], regardless of whether it is applied to the applying means or the separating means. If the angle θ of the static elimination brush with respect to the ideal medium conveyance surface I is 45 degrees ≦ θ ≦ 90 degrees, and if 174 [mm / sec] <V ≦ 347 [mm / sec], the angle θ is 45 degrees ≦ By setting θ ≦ 75 degrees, the present invention can be applied to any embodiment. This can be similarly applied to the first and second embodiments when used together with the definition of the length of the linear body in the other embodiments.

  Furthermore, in the first to sixth embodiments, the case where the image forming apparatus 10 is a printer has been described. However, in the present invention, the image forming apparatus 10 is a copying machine, a facsimile machine, a multifunction machine, or the like. Can also be applied.

  In addition, this invention is not limited to the said embodiment, It can change variously based on the meaning of this invention, and does not exclude them from the scope of the present invention.

FIG. 4 is a cross-sectional view of the main part of the fixing device according to the first embodiment of the present invention, and is a cross-sectional view taken along the line ZZ in FIG. 3. 1 is a schematic side view illustrating an image forming apparatus including a fixing device according to a first embodiment of the present invention. FIG. 2 is an external perspective view of the fixing device according to the first embodiment of the present invention viewed from the recording medium discharge direction. FIG. 3 is an exploded perspective view of the fixing device according to the first embodiment of the present invention viewed from the recording medium discharge direction. It is sectional drawing of the static elimination brush in the 1st Embodiment of this invention. It is an enlarged view of the support part attachment opening of the static elimination brush in the 1st Embodiment of this invention. It is an enlarged view which shows the other example of the support part attachment opening of the static elimination brush in the 1st Embodiment of this invention. FIG. 10 is a cross-sectional view of main parts of a fixing device according to a second embodiment of the present invention, and is a cross-sectional view taken along the line ZZ in FIG. 9. FIG. 6 is an external perspective view of a fixing device according to a second embodiment of the present invention viewed from a recording medium discharge direction. FIG. 6 is an exploded perspective view of a fixing device according to a second embodiment of the present invention viewed from a recording medium discharge direction. It is sectional drawing of the static elimination brush in the 2nd Embodiment of this invention. FIG. 10 is a perspective view of a fixing device according to a third embodiment of the present invention. FIG. 9 is an exploded perspective view of a fixing device according to a third embodiment of the present invention. FIG. 13 is a cross-sectional view of a main part of a fixing device according to a third embodiment of the present invention, and is a cross-sectional view taken along the line ZZ in FIG. 12. FIG. 10 is a cross-sectional view of a main part of a fixing device according to a third embodiment of the present invention. It is sectional drawing of the static elimination brush in the 3rd Embodiment of this invention. It is a front view of the static elimination brush in the 3rd Embodiment of this invention. FIG. 10 is a diagram illustrating an image pattern used in an evaluation test of a fixing device according to a third embodiment of the present invention. 10 is a table showing the results of evaluating the occurrence of electrostatic offset of the fixing device according to the third embodiment of the present invention. FIG. 10 is a scatter diagram illustrating a relationship between the number of linear body damages and the length of a linear body of a fixing device according to a third embodiment of the present invention. FIG. 10 is a scatter diagram illustrating the relationship between the number of linear object damages and the number of printed sheets for each inclination angle of a static elimination brush of a fixing device according to a third embodiment of the present invention. FIG. 10 is a perspective view of a main part of a fixing device according to a fourth embodiment of the present invention. It is a principal part side view of the fixing device in the 4th Embodiment of this invention. It is the figure which showed the relationship between the number of printed sheets of a recording medium, and the number of damage of a linear body for every inclination-angle of the static elimination brush in the 4th Embodiment of this invention. It is a principal part side view of the fixing device in the 5th Embodiment of this invention. It is a principal part side view of the fixing device in the 6th Embodiment of this invention. It is a principal part front view of the fixing device in the 6th Embodiment of this invention.

Explanation of symbols

10 Image forming device 15 Recording medium 30, 700, 800, 900 Fixing device 34a, 34b Side plate 44, 811 Fixing roller 45, 812 Pressure roller 61, 702 Static elimination brush 62, 702a Thin plate 63, 702b Linear body 65, 701 Cover Member 71 Frame member 701a Sticking member 702-up Upper static elimination brush 702-low Lower static elimination brush 702a-low Lower thin plate 702b-uppp Upper linear body 702b-low Lower linear body 820 Separation plate 820a Separation part 820b, 833b Inclination Portion 820c Stainless steel plate portion 830 Separating member 833 Stainless steel plate member 833b-low Inclined portion of lower stainless steel plate member

Claims (12)

(A) a fixing member that fixes the image formed on the medium by heating the medium;
(B) a pressure member that is pressed against the fixing member and presses the medium against the fixing member;
(C) a frame member that supports the fixing member and the pressure member;
(D) a cover member that covers the frame member;
(E) a fixing device having a static elimination member for removing static electricity accumulated in the medium,
(F) The fixing device, wherein the charge removal member is sandwiched and pressed between the cover member and a frame member. The fixing device according to claim 1, wherein the frame member is formed of a conductive member, and the charge removal member is grounded via the frame member. The static elimination member includes a linear body that contacts the medium, and a support portion that supports the linear body,
The fixing device according to claim 1, wherein at least both end portions of the support portion are clamped and held between the cover member and the frame member. The fixing device according to claim 3, wherein the support portion is further adhered to the frame member. The frame member is disposed apart from the medium conveyance surface of the fixing member and the pressure member, and forms a predetermined angle with respect to the medium conveyance surface, and faces the fixing member or the pressure member. With an inclined ramp,
The support portion is attached to the inclined portion,
The fixing device according to claim 3, wherein the linear body extends along an inclination of the inclined portion and intersects the medium conveyance surface. The fixing device according to claim 5, wherein the inclined portion is formed on a side where the pressure member is disposed with respect to the medium conveyance surface. When the length of the portion protruding from the support portion in the linear body is L1, and the length to the portion intersecting the medium conveyance surface in the portion protruding from the support portion is L2,
L1 and L2 are 2 [mm] ≦ (L1−L2) ≦ 5 [mm] and (L1−L2) −L2 <0.
The fixing device according to claim 5, wherein: When the medium conveyance speed at which the medium is conveyed is V and the predetermined angle formed by the inclined portion with respect to the medium conveyance surface is θ,
The fixing device according to claim 7, wherein the V and θ satisfy V ≦ 174 [mm / sec] and 45 degrees ≦ θ ≦ 90 degrees. When the medium conveyance speed at which the medium is conveyed is V and the predetermined angle formed by the inclined portion with respect to the medium conveyance surface is θ,
The fixing device according to claim 7, wherein the V and θ satisfy 174 [mm / sec] <V ≦ 347 [mm / sec] and 45 degrees ≦ θ ≦ 75 degrees. The fixing device according to claim 5, wherein the inclined portion includes a guide portion that contacts the medium and guides conveyance of the medium. The fixing device according to claim 10, wherein a plurality of the linear bodies are arranged except for an area overlapping with a position of the guide portion. An image forming apparatus equipped with the fixing device according to claim 1.

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