JP2013127573A - Fixing device and image forming apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a fixing device capable of setting a gap between a fixing member and a peeling auxiliary member within a predetermined range without requiring special adjustment operations.SOLUTION: There is provided a fixing device which comprises: a fixing belt 102 which is in contact with a recording paper P while rotating to fix a toner image on the recording paper P; a pair of side frames 148 for rotatably supporting the fixing belt 102 on both sides in the axial direction; a baffle plate 140 which is opposed to the fixing belt 102 in a gap to assist the peeling of the recording paper P from the fixing belt 102; (a small diameter part 162 of) a positioning pin as a positioning part for positioning the baffle plate 140 at least in two different directions along an orthogonal plane orthogonal to the axial direction of the fixing belt 102 with respect to the side frames 148; a round hole 154; and a long hole 156.

Description

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

  In Patent Document 1, as shown in FIG. 1 and the like, a housing (7) that rotatably supports the heat roller (3) is opposed to the outlet EX side of the heat roller (3) with a slight gap therebetween. The separation guide (9) for separating the recording medium from the heat roller (3) is integrally formed, so that no special adjustment work is required and the number of parts is not increased. ) And the separation guide are set to an optimum value.

  In Patent Document 2, as shown in FIGS. 1 and 3, the separation of the recording paper P subjected to the fixing process by the fixing member (31) on the downstream side in the rotation direction of the fixing member (31) is assisted. A support for attaching the peeling guide member (49) in the peeling apparatus provided with the peeling guide member (49) so that the tip of the peeling guide member (49) is not in contact with the surface of the fixing member (31). There is a technique in which the member (54) is brought into contact with a bearing member (39) that rotatably supports the fixing member (31) so that the peeling guide member (49) is positioned with respect to the fixing member (31). Have been described.

JP-A-9-230730 JP 2003-122171 A

  It is an object of the present invention to provide a fixing device that can set a gap between a fixing member and a peeling assisting member within a predetermined range without requiring any special adjustment work.

  According to a first aspect of the present invention, there is provided a fixing device that contacts a recording medium while rotating and fixes a toner image on the recording medium, and a pair of support members that rotatably support the fixing member on both sides in the axial direction. A separation assisting member that opposes the fixing member with a gap and assists the separation of the recording medium from the fixing member, and at least the separation assisting member with respect to the support member. And a positioning portion for positioning in two different directions along an orthogonal plane orthogonal to the direction.

  The fixing device according to a second aspect of the present invention is the fixing device according to the first aspect, wherein the positioning portion is formed in a positioning hole formed in the support member and on both sides of the peeling assisting member. The positioning pin includes a small-diameter portion that can be fitted into the positioning hole, a large-diameter portion that cannot be fitted into the positioning hole, and a boundary between the small-diameter portion and the large-diameter portion. The step portion is in contact with the support member on both sides of the peeling assisting member.

  According to a third aspect of the fixing device of the present invention, in the fixing device according to the first aspect, the peeling assisting member includes a metal member formed of a resin material and attached by integral molding. Both ends are fixed to the support member.

  The fixing device according to a fourth aspect of the present invention is the fixing device according to any one of the first to third aspects, wherein the fixing member is a flexible annular belt, and the fixing auxiliary member is the fixing member. The shape of the edge facing the belt corresponds to the shape of a defining member that contacts the belt from the inside of the belt and defines the shape of the belt in the axial direction.

  An image forming apparatus according to a fifth aspect of the present invention includes an image carrier on which an electrostatic latent image is formed, a developing device that develops the electrostatic latent image formed on the image carrier with toner, and the developing device. A transfer device that transfers a developed toner image to a recording medium, and a fixing device according to claim 1 that fixes the toner image transferred to the recording medium to the recording medium. It is characterized by that.

  According to the fixing device of the first aspect of the present invention, the fixing device does not require any special adjustment work as compared with the case where the other member interposed between the supporting member and the peeling assisting member has a positioning portion. The gap between the member and the peeling assisting member can be set within a predetermined range.

  According to the fixing device of the second aspect of the present invention, the separation assisting member can be positioned in the axial direction as compared with the case where the positioning pin is not provided with the stepped portion for contacting the support member.

  According to the fixing device of the third aspect of the present invention, it is supported by the thermal expansion of the peeling auxiliary member as compared with the case where the metal member for connecting to the supporting member is not attached to the peeling auxiliary member formed of a resin material. It can suppress that the space | interval of a member changes.

  According to the fixing device of the fourth aspect of the present invention, the shape of the edge of the peeling assisting member facing the belt contacts the belt from the inside of the belt and defines the shape in the axial direction of the belt. Compared to the case where the belt does not correspond to the above, the gap between the belt and the peeling assisting member can be set to a predetermined range in the axial direction.

  According to the image forming apparatus of the fifth aspect of the present invention, the image forming apparatus can be separated from the fixing member without requiring any special adjustment work as compared with the case where the fixing apparatus according to any one of the first to fourth aspects is not provided. The gap with the auxiliary member can be set within a predetermined range, and an image with excellent image quality can be formed on the recording medium.

1 is a diagram illustrating a configuration of an image forming apparatus according to an embodiment of the present invention. It is a figure which shows the structure of the image forming unit of FIG. FIG. 2A is a diagram illustrating a configuration of the fixing device in FIG. 1. 2B is a cross-sectional view of the fixing belt in FIG. FIG. 2 is a cross-sectional perspective view showing a support structure for the fixing belt of FIG. 1. It is a figure which shows the attachment structure of the baffle of FIG. 3 (A). It is a figure which shows the attachment structure of the baffle of FIG. 3 (A). It is a figure which shows the attachment structure of the baffle of FIG. 3 (A). It is a figure which shows the attachment structure of the baffle as a modification of the baffle of FIG. 3 (A). It is a figure which shows the attachment structure of the baffle as a modification of the baffle of FIG. 3 (A). It is a figure which shows the attachment structure of the baffle as a modification of the baffle of FIG. 3 (A). It is a perspective view which shows the attachment structure of the baffle as a comparative example of the baffle of FIG. 3 (A). (A) (B) (C) (D) It is a figure which shows the correspondence of the shape of a baffle main-body part, and the shape of a pad.

  An example of a fixing device and an image forming apparatus according to the present invention will be described.

(Image forming device)
FIG. 1 shows an image forming apparatus 10 according to the present invention. The image forming apparatus 10 includes a sheet storage unit 12 that stores recording paper P from the lower side to the upper side in the vertical direction (the arrow Y direction in the drawing), and the sheet storage unit 12 that is provided on the sheet storage unit 12. An image forming unit 14 that forms an image on the recording paper P supplied from the paper, a discharge unit 16 that is integrally provided on the upper left side of the image forming unit 14 and discharges the recording paper P on which the image is formed, A document reading unit 18 provided on the image reading unit G for reading the read document G and a control unit 20 provided in the image forming unit 14 for controlling the operation of each unit of the image forming apparatus 10 are configured. In the following description, the left-right direction of the image forming apparatus 10 is referred to as an arrow X direction, the up-down direction is referred to as an arrow Y direction, and the depth direction is referred to as an arrow Z direction. The Z direction is the same as the axial direction of the fixing belt 102 described later, the axial direction of the pad 118, and the axial direction of the baffle 000 (baffle body 000).

  In the paper storage unit 12, the first storage unit 22, the second storage unit 24, the third storage unit 26, and the fourth storage unit 28 in which recording papers P having different sizes as an example of a recording medium are stored are in the arrow Y direction. It is provided side by side. The first storage unit 22, the second storage unit 24, the third storage unit 26, and the fourth storage unit 28 send out the stored recording paper P to the transport path 30 provided in the image forming apparatus 10. A pair of transport rolls 34 and a transport roll 36 for transporting the recording paper P one by one are provided on the downstream side of the feed roll 32 in the transport path 30. In addition, the recording paper P is stopped at one end in the image forming section 14 and downstream of the conveying roll 36 in the conveying direction of the recording paper P in the conveying path 30, and the secondary transfer section 37 (at a predetermined timing). An alignment roll 38 is provided for feeding to a later-described detail.

  The image forming unit 14 includes a housing 16A that is an apparatus main body. In the housing 16 </ b> A, the upper left portion of the image forming unit 14 protrudes above the upper center portion and the upper right portion in a front view of the image forming apparatus 10. The left end of the document reading unit 18 is coupled to the upper end of the discharge unit 16. As a result, the image forming apparatus 10 has a discharge area 19 surrounded by the upper surface of the image forming unit 14, the lower surface of the document reading unit 18, and the right side surface of the discharge unit 16. In the discharge area 19, the recording paper P is discharged and stacked from the discharge unit 16.

  A foldable manual sheet feeding unit 39 provided on the left side of the image forming apparatus 10 on the opposite side of the conveyance roll 36 of the fourth storage unit 28 across the conveyance path 30 of the image forming unit 14. A preliminary transport path 40 through which the recording paper P is transported to the transport path 30 is provided. The preliminary conveyance path 40 includes a delivery roll 42 that sends the recording paper P of the manual paper feed unit 39 to the preliminary conveyance path 40, and a plurality of recording papers P that are provided downstream of the delivery roll 42 and convey the recording paper P one by one. A transport roll 44 is provided, and the downstream end of the preliminary transport path 40 is connected to the transport path 30.

  Further, a fixing device 100 is provided in the image forming unit 14 on the downstream side of the secondary transfer unit 37 in the conveyance path 30. The fixing device 100 includes a fixing belt 102 that heats the developer (toner) on the recording paper P, and a pressure roll 104 that presses the recording paper P toward the fixing belt 102. When the toner passes through a nip portion N (see FIG. 3A) that is a contact portion between the fixing belt 102 and the pressure roll 104, the toner is melted and solidified to fix the toner image on the recording paper P. Yes. Details of the fixing device 100 will be described later.

  As shown in FIGS. 1 and 2, at the center of the image forming unit 14, a toner image is formed on the recording paper P by combining toners of black (K), yellow (Y), magenta (M), and cyan (C). An image forming unit 60 for forming (developer image) is provided. In the image forming unit 60, photoconductors 62K, 62Y, 62M, and 62C as an example of a holding body that holds a latent image are black (K), yellow (Y), magenta (M), and cyan (C). It is provided corresponding to the toner. In the following description, when it is necessary to distinguish between K, Y, M, and C, an alphabetic letter of any one of K, Y, M, and C will be added after the number, and the same configuration will be used. , Y, M, and C need not be distinguished from each other, the description of K, Y, M, and C is omitted.

  The photoconductors 62K, 62Y, 62M, and 62C are arranged in this order toward the upper right side in the figure, and rotate in the direction of the arrow b (counterclockwise direction in the figure) and are formed by light irradiation. The latent image is held on the outer peripheral surface. Further, around each of the photoconductors 62K, 62Y, 62M, and 62C, a charging roll 66, an LED (Light Emitting Diode) head 68, a developing device 72, an intermediate transfer belt 64 (primary transfer roll) are sequentially arranged along the arrow b direction. 74), and a cleaning roll 76 is provided.

  As an example, the charging roll 66 has a configuration in which a plurality of layers (all not shown) including a conductive elastic layer, an intermediate layer, and a surface resin layer are formed around a shaft portion made of stainless steel. The charging roll 66 is rotatably provided with a shaft portion so that the outer peripheral surface is in contact with the surface layer of the photoconductor 62 and is driven by a voltage applied from a voltage application unit (not shown). The outer peripheral surface of the photoreceptor 62 is charged by the generated discharge.

  The LED head 68 forms an electrostatic latent image by irradiating (exposing) light corresponding to each toner color on the outer peripheral surface of the photoreceptor 62 charged by the charging roll 66. As a means for exposing the photosensitive member 62, a method of scanning laser light with a polygon mirror in common for four colors K, Y, M, and C may be used.

  The developing device 72 supplies a developer to the latent image formed on the photoreceptor 62 to form a developer image (toner image), a conveying member 73A that circulates and conveys the developer to the developing roller 71, and 73B. As the developer, either a two-component developer mainly containing toner and a carrier or a one-component developer mainly containing toner may be used.

  The intermediate transfer belt 64 is formed in an endless shape, and includes a belt conveyance roll 82 provided in the secondary transfer unit 37, a belt conveyance roll 84 provided on the lower right side of the belt conveyance roll 82, and a belt conveyance roll 82. Is wound around a driving roll 86 that is provided obliquely above and to the right and is driven by a motor (not shown), and is supported so as to be capable of rotating in the direction of arrow a (clockwise direction in the figure). The outer peripheral surface of the intermediate transfer belt 64 is a transfer surface onto which the toner image is transferred. The transfer surfaces from the drive roll 86 to the belt conveyance roll 84 of the intermediate transfer belt 64 are arranged with the photosensitive members 62K, 62Y, 62M, and 62C. The outer peripheral surface is in contact.

  On the other hand, primary transfer rolls 74 (74K, 74Y, 74M, and 74C) are provided on the opposite side of the photoreceptors 62K, 62Y, 62M, and 62C with the intermediate transfer belt 64 interposed therebetween. The primary transfer roll 74 is in contact with the inner peripheral surface of the intermediate transfer belt 64, and a voltage is applied from a voltage application unit (not shown), so that a potential difference from the grounded photoconductor 62 is caused by a potential difference from the grounded photoconductor 62. The toner image is primarily transferred onto the transfer surface of the intermediate transfer belt 64. As a result, the toner images are transferred onto the intermediate transfer belt 64 while the intermediate transfer belt 64 makes one round.

  A toner density detection sensor 88 is provided on the opposite side of the intermediate transfer belt 64 from the belt conveyance roll 84. The toner density detection sensor 88 has a function of detecting the density of the toner image transferred to the transfer surface of the intermediate transfer belt 64. Further, a cleaning member 92 that cleans the toner remaining on the transfer surface of the intermediate transfer belt 64 after the secondary transfer is provided on the opposite side of the drive roll 86 across the intermediate transfer belt 64.

  The secondary transfer unit 37 includes a belt conveyance roll 82 around which the intermediate transfer belt 64 is wound, and a secondary transfer roll 89 provided on the opposite side of the belt conveyance roll 82 with the intermediate transfer belt 64 interposed therebetween. Yes. A voltage is applied to the belt conveyance roll 82 or the secondary transfer roll 89 from a voltage application unit (not shown). Due to the potential difference between the belt conveyance roll 82 and the secondary transfer roll 89, an intermediate transfer belt is provided. The toner image on 64 is secondarily transferred onto the recording paper P. As described above, the toner image formed on the photosensitive member 62 is transferred onto the recording paper P by the transfer device including the primary transfer roll 74, the secondary transfer roll 89, and the intermediate transfer belt 64.

  As shown in FIG. 1, on the right side of the cleaning member 92 of the image forming unit 14, a toner cartridge 77K that contains toners of black (K), yellow (Y), magenta (M), and cyan (C), 77Y, 78M, and 78C are provided to be replaceable. Further, on the left side of the conveyance path 30 of the image forming unit 14, there is provided a double-sided conveyance path 94 through which the recording paper P is conveyed and reversed in order to form an image on both sides of the recording paper P.

  The double-sided conveyance path 94 is provided on the downstream side of the fixing device 100 in the conveyance direction of the recording paper P in the conveyance path 30 and the downstream side of the conveyance roll 95 so that the rotation direction can be switched. The other end is connected to the upstream side of the alignment roll 38. The double-sided conveyance path 94 is provided with a plurality of conveyance rolls 97 that convey the recording paper P fed from the conveyance roll 96 toward the alignment roll 38. Thereby, at the time of double-sided image formation, the recording paper P on which the toner image is fixed on the front side by the fixing device 100 enters the double-sided conveyance path 94 by the reverse rotation of the conveyance roll 96 and a path switching member (not shown), and again By entering the alignment roll 38, the front and back of the recording paper P are reversed.

  The recording paper P is discharged to a lower base 52 provided on the upper portion of the image forming unit 14 in the conveyance path 31 branched from the conveyance path 30 to the discharge area 19 side downstream of the conveyance roll 95 in the discharge unit 16. A lower discharge roll 54 is provided. At a position adjacent to the lower discharge roll 54, a lower detection unit 55 for detecting the stacking height of the recording paper P stacked on the lower table 52 is provided. Further, an upper discharge roll 57 that discharges the recording paper P to an upper table 56 provided above the lower table 52 is provided in the conveyance path 30 on the downstream side of the conveyance roller 95 in the discharge unit 16A. An upper detection unit 58 for detecting the stacking height of the recording sheets P stacked on the upper table 56 is provided at a position adjacent to the upper discharge roll 57.

  On the other hand, the document reading unit 18 includes a document transport device 45 that automatically transports the read document G one by one, a platen glass 47 that is disposed below the document transport device 45 and on which one read document G is placed, and a document A document reading device 49 that reads the read document G conveyed by the conveyance device 45 or the read document G placed on the platen glass 47 is provided. The document conveyance device 45 has an automatic conveyance path 48 in which a plurality of pairs of conveyance rolls 46 are arranged, and a part of the automatic conveyance path 48 is arranged so that the recording paper P passes over the platen glass 47. . The document reading device 49 reads the read document G conveyed by the document conveying device 45 in a state of being stationary at the left end portion of the platen glass 47, or is read on the platen glass 47 while moving in the arrow X direction. G is read.

(Image formation process)
Next, an image forming process in the image forming apparatus 10 will be described.

  As shown in FIG. 1, when the image forming apparatus 10 operates, image data of each color of black (K), yellow (Y), magenta (M), and cyan (C) is supplied from an image processing apparatus (not shown) or from the outside. Is output to the LED head 68 (see FIG. 2). Subsequently, the light emitted from the LED head 68 according to the image data exposes the outer peripheral surface (surface) of the photoconductor 62 charged by the charging roll 66, and image data of each color is formed on the surface of each photoconductor 62. An electrostatic latent image corresponding to is formed. Further, the electrostatic latent image formed on the surface of each photoconductor 62 is developed as a toner image by each developing device 72. The toner image on the surface of each photoconductor 62 is sequentially multiplex-transferred onto the intermediate transfer belt 64 by the primary transfer roll 74.

  On the other hand, the recording paper P sent out from the paper storage unit 12 and conveyed through the conveyance path 30 is aligned with the multiple transfer of each toner image onto the intermediate transfer belt 64 by the alignment roll 38, and the secondary transfer unit. It is conveyed to 37. The toner image that has been multiple-transferred onto the intermediate transfer belt 64 is secondarily transferred by the secondary transfer roll 89 onto the recording paper P that has been conveyed to the secondary transfer unit 37.

  Subsequently, the recording paper P onto which the toner image has been transferred is conveyed to the fixing device 100. In the fixing device 100, the toner image is fixed on the recording paper P by being heated and pressed by the fixing belt 102 and the pressure roll 104. Further, the recording paper P on which the toner image is fixed is discharged from the discharge unit 16 to the lower table 52 or the upper table 56. When forming images on both sides of the recording paper P, after fixing the image on the front surface by the fixing device 100, the lower end of the recording paper P is fed from the conveying roll 96 to the double-sided conveying path 94 and the alignment roll 38 is used. By sending out to the (conveyance path 30), the leading edge and the trailing edge of the recording paper P are switched. Then, image formation and fixing on the back surface of the recording paper P are performed.

(Fixing device)
Next, the fixing device 100 will be described in detail.

  As shown in FIG. 3A, the fixing device 100 includes a housing 122 in which an opening for entering or discharging the recording paper P is formed. Inside the housing 122, a flexible endless fixing belt 102 as an example of a fixing member rotated in the direction of arrow D is provided. The fixing belt 102 is rotatably supported by a side frame 148 as an example of a support member described later.

  As shown in FIG. 3B, the fixing belt 102 includes a base layer 126, a heat generating layer 128, a protective layer 130, an elastic layer 132, and a release layer 134 from the inside to the outside, and these are laminated. It is united.

  The base layer 126 serves as a base for maintaining the strength of the fixing belt 102, and is made of polyimide (PI) as an example. As another example of the base layer 126, nonmagnetic stainless steel may be used. The heat generating layer 128 is a metal material that generates heat by an electromagnetic induction effect in which an eddy current flows so as to generate a magnetic field that cancels the magnetic field H (see FIG. 3A), and copper is used as an example. And the protective layer 130 is comprised with the synthetic resin, and is comprised with the same polyimide as the base layer 126 as an example.

  The elastic layer 132 is made of silicon rubber or fluorine rubber from the viewpoint of obtaining excellent elasticity and heat resistance. In the present embodiment, silicon rubber is used as an example. Further, the release layer 134 is provided to weaken the adhesive force with the toner image G (see FIG. 3A) melted on the recording paper P so that the recording paper P can be easily peeled from the fixing belt 102. It has been. In this embodiment, as an example, the release layer 134 is formed of PFA (tetrafluoroethylene / perfluoroalkoxyethylene copolymer resin).

  As shown in FIG. 3A, a bobbin 108 made of an insulating material is disposed at a position facing the outer peripheral surface of the fixing belt 102. The bobbin 108 is formed in an arc shape that follows the outer peripheral surface of the fixing belt 102, and a protrusion 108 </ b> A is provided on the opposite side of the fixing belt 102. An exciting coil 110 is wound around the bobbin 108 a plurality of times in the axial direction (the depth direction in FIG. 3A) around the convex portion 108A. Also, on the opposite side of the bobbin 108 with the exciting coil 110 in between, a magnetic core 112 made of a ferrite-based magnetic body formed in an arc shape following the arc shape of the bobbin 108 is disposed and supported by the bobbin 108. ing.

  As an example, a fixing member 114 having a pipe shape formed of non-magnetic aluminum is disposed inside the fixing belt 102 in a non-contact state with the fixing belt 102. A magnetic core 116 made of the same material as that of the magnetic core 112 is attached to the bobbin 108 side of the fixing member 114 by an attachment member 115. The magnetic core 116 is in a non-contact state with the fixing belt 102, and a closed magnetic path is formed between the magnetic core 116 and the magnetic core 112 by the magnetic field H penetrating the fixing belt 102, and the magnetic field H is strengthened. It is like that.

  Further, a pad 118 as an example of a defining member that contacts the fixing belt 102 from the inside of the fixing belt 102 and defines the shape of the fixing belt 102 in the Z direction is fixed to the opposite side of the fixing member 114 to the bobbin 108 side. Has been. The pad 118 is made of resin as an example.

  On the other hand, at a position facing the outer peripheral surface of the fixing belt 102, the fixing belt 102 and the recording paper P are pressurized toward the pad 118 and rotated in the direction of arrow E by a drive mechanism (not shown) including a motor and a gear. A pressure roll 104 is provided. The fixing belt 102 is driven and rotated by the pressure roll 104, and the recording paper P enters the nip portion N that is a contact portion between the fixing belt 102 and the pressure roll 104 in the direction of the arrow IN, and from the direction of the arrow OUT. It is supposed to be discharged.

  For example, the pressure roll 104 has a configuration in which a metal core 106 made of metal is coated with silicon rubber and PFA. The pressure roll 104 can be moved in the direction of arrow A (direction approaching the fixing belt 102) or the direction of arrow B (direction away from the fixing belt 102) by a retract mechanism (not shown). To the outer peripheral surface of the fixing belt 102 and pressurize, or move in the direction of the arrow B to move away from the outer peripheral surface of the fixing belt 102.

  A baffle 140 as an example of a separation assisting member that assists the separation of the recording paper P from the fixing belt 102 is provided in the vicinity of the recording paper P discharge opening in the nip portion N. The baffle 140 is disposed to face the fixing belt 102 with a gap. The baffle 140 is formed in a tapered shape so that the tip portion approaching the fixing belt 102 becomes thinner toward the fixing belt 102.

  If the gap between the baffle 140 and the fixing belt 102 is too wide, the function of assisting the separation of the recording paper P from the fixing belt 102 is deteriorated. On the other hand, if the gap is too narrow, the baffle 140 contacts the fixing belt 102 and the image on the fixing belt 102 is reduced. Since scratches that cause defects are attached, a predetermined range, for example, 0.5 ± 0.1 mm is set.

  FIG. 4 is a cross-sectional perspective view showing a support structure for the fixing belt 102. The fixing belt 102 is fitted into the belt gear 142 at the end and is fixed to the belt gear 142. The belt gear 142 is rotatably connected to the block shaft 146 via a bearing 144. The block shaft 146 is attached and fixed to the side frame 148 by the attachment member 150 on one end side (outside). A fixing member 114 is attached to the other end side (inner side) of the block shaft 146, and a pad 118 is fixed to one side of the fixing member 114. Although FIG. 4 shows a support structure on one end side of the fixing belt 102, the other end side of the fixing belt 102 has a similar support structure.

  That is, the fixing belt 102 is rotatably supported by the pair of side frames 148 on both sides in the Z direction via the block shaft 146, the bearing 144, and the belt gear 142. Note that the side frame 148 on one end side and the side frame 148 on the other end side are connected by a connecting frame 152.

  5 to 7 show the mounting structure of the baffle 140. 5 shows the mounting structure of the baffle 140 when viewed from the Z direction, FIG. 6 shows the mounting structure of the baffle 140 when viewed from the Y direction, and FIG. 7 shows the mounting structure of the baffle 140 when viewed from the X direction. The structure is shown.

  The baffle 140 has a long shape in the Z direction, and is attached to the side frame 148 while being positioned with respect to the side frame 148 at both ends in the Z direction. Each of the pair of side frames 148 is formed with one round hole 154 and one long hole 156 as examples of positioning holes, separated from each other in the Y direction. The round hole 154 and the long hole 156 are formed at predetermined positions with respect to the reference position P that supports the fixing belt 102 in the side frame 148. The round hole 154 is formed at a position closer to the fixing belt 102 than the long hole 156.

  The baffle 140 is formed with two positioning pins 160 that protrude outward from both sides of the baffle main body 158 on each side. Each positioning pin 160 includes a small diameter portion 162 that can be fitted into the round hole 154 or the long hole 156 of the side frame 148, a large diameter portion 164 that cannot be fitted into the round hole 154 or the long hole 156 of the side frame 148, and a small diameter. And a step 166 formed at the boundary between the portion 162 and the large diameter portion 164. Both the baffle body 158 and the positioning pins 160 are made of a resin material.

  The outer diameter of the small diameter portion 162 of the positioning pin 160 and the inner diameter of the round hole 154 are substantially the same. Further, the outer diameter of the small diameter portion 162 of the positioning pin 160 and the diameter of the long hole 156 in the short direction are substantially the same. Therefore, the small diameter portions 162 of the two positioning pins 160 on both sides of the baffle 140 are fitted into the round holes 154 and the long holes 156 of the side frames 148, respectively, so that the baffle 140 is in the XY plane with respect to the side frames 148. Positioning is performed in two directions along (an orthogonal plane orthogonal to the Z direction). Further, the stepped portions 166 of the positioning pins 160 come into contact with the side frames 148 on both sides of the baffle 140, whereby the baffle 140 is positioned in the Z direction. Then, the baffle 140 is attached to the side frame 148 by connecting the connection frame 152 to each side frame 148 in a state where the positioning pins 160 of the baffle 140 are fitted in the round holes 154 and the long holes 156 of each side frame 148. .

  8 to 10 show a mounting structure of a baffle 170 as a modification to the baffle 140. 8 shows the mounting structure of the baffle 170 when viewed from the Z direction, FIG. 9 shows the mounting structure of the baffle 170 when viewed from the Y direction, and FIG. 10 shows the mounting structure of the baffle 170 when viewed from the X direction. The structure is shown.

  In the baffle 170, a total of four positioning pins 172 projecting from both sides of the baffle main body 158 do not have the large-diameter portion 164 and the stepped portion 166, but only the small-diameter portion 162. The four positioning pins 172 are fitted in the corresponding round holes 154 and long holes 156 of the side frames 148, respectively. Thereby, the baffle 170 is positioned with respect to each side frame 148 in two directions along the XY plane (orthogonal plane orthogonal to the Z direction).

  A tie plate 174 as an example of a metal member made of stainless steel is attached to one surface of the baffle main body 158 by integral molding such as insert molding. As shown in FIG. 9, the tie plate 174 includes a flat plate portion 176 along the baffle main body portion 158 and attachment portions 178 formed by being bent at both ends in the longitudinal direction of the flat plate portion 176. The distance between the outer surfaces of the mounting portion 178 is substantially the same as the distance between the pair of side frames 148. The attachment portions 178 on both ends of the tie plate 174 are provided with screw holes 182 for fixing the attachment screws 180 respectively. Each side frame 148 is provided with an insertion hole 184 (see FIG. 9) for inserting the attachment screw 180 in addition to the round hole 154 and the long hole 156. The attachment portions 178 on both ends of the tie plate 174 are connected and fixed to the side frame 148 with attachment screws 180. Thereby, the baffle 170 is positioned in the Z direction. The insertion hole 184 is set to be larger than the outer diameter of the shaft portion of the mounting screw 180.

  FIG. 11 is a perspective view showing a mounting structure of a baffle 200 as a comparative example with respect to the baffles 140 and 170.

  The baffle 200 as a comparative example has a separation structure in which the baffle body 202 and the tie plate 204 are separated from each other, and a plurality of adjustment screws (only one is shown in FIG. 11) attached at intervals in the Z direction. The baffle body 202 is attached to the tie plate 204 by 206. The tie plate 204 is attached to the side frame 148 with attachment screws 208 (only one is shown on one side in FIG. 11) at both ends. In the baffle 200 as a comparative example, the tie plate 204 is first attached to the side frame 148, and then the baffle body 202 is attached to the tie plate 204. When attaching the baffle body 202 to the tie plate 204, the baffle body 202 is displaced with respect to the tie plate 204 with the adjustment screw 206 loosened, and the gap between the baffle body 202 and the fixing belt 102 is previously set. The baffle main body 202 is attached to the tie plate 204 while adjusting so as to be within a predetermined range.

  In contrast to the mounting structure of the baffle 200 shown in FIG. 11, in the mounting structure of the baffle 140 shown in FIGS. 5 to 7, the positioning pins 160 provided on both sides of the baffle main body 158 have round holes 154 in the side frame 148. The baffle 140 is attached while being positioned with respect to the side frame 148 by being fitted into the long hole 156. That is, the positioning pin 160 of the baffle 140 is fitted into the round hole 154 and the long hole 156 that are formed in a predetermined position with respect to the reference position P that supports the fixing belt 102 in the side frame 148 that supports the fixing belt 102. As a result, the gap between the baffle main body 158 and the fixing belt 102 is set within a predetermined range.

  In contrast to the mounting structure of the baffle 200 shown in FIG. 11, in the mounting structure of the baffle 170 shown in FIG. 8 to FIG. The baffle 170 is mounted while being positioned with respect to the side frame 148 by being fitted into the round hole 154 and the long hole 156. That is, the positioning pin 172 of the baffle 170 is fitted into the round hole 154 and the long hole 156 that are formed at positions predetermined with respect to the position where the fixing belt 102 is supported in the side frame 148 that supports the fixing belt 102. Thus, the gap between the baffle body 158 and the fixing belt 102 is set to a predetermined range.

  In the mounting structure of the baffle 140 shown in FIGS. 5 to 7, the baffle 140 is positioned in the Z direction by bringing the step 166 of the positioning pin 160 into contact with the side frame 148. Since the expansion coefficient is made of a resin material having a relatively large expansion coefficient, a force in a direction in which the baffle 140 (especially the baffle body portion 158) is expanded is applied to the side frame 148 due to thermal expansion in the Z direction. That is, the interval between the pair of side frames 148 changes due to the thermal expansion of the baffle 140.

  On the other hand, in the attachment structure of the baffle 170 shown in FIGS. 8 to 10, a metal tie plate 174 having a smaller thermal expansion coefficient than the resin material is connected and fixed to the side frame 148. Since the positioning pin 172 does not have the stepped portion 166, displacement of the positioning pin 172 in the Z direction with respect to the round hole 154 or the long hole 156 is allowed. Therefore, a change in the interval between the side frames 148 due to thermal expansion in the Z direction of the baffle 170 (particularly the baffle main body 158) is suppressed.

  FIG. 12 shows the correspondence between the shape of the baffle body 158 and the shape of the pad 118 in the baffle 140 (or baffle 170). FIG. 12A shows the positional relationship between the baffle body 158 and the fixing belt 102 with respect to the pad 118 when the pad 118 is viewed from the Z direction. FIG. 12B shows the shape of the pad 118 when viewed from the Y direction, and the shape of the surface of the pad 118 facing the baffle body 158. FIG. 12C shows the positional relationship between the pad 118 and the fixing belt 102 with respect to the baffle body 158 when the baffle body 158 is viewed from the Z direction. FIG. 12D shows the shape of the baffle main body 158 when viewed from the X direction and the shape of the surface side of the baffle main body 158 that contacts the recording paper P. FIG. An arrow D in the figure indicates the moving direction of the fixing belt 102, and an arrow E indicates the conveyance direction of the recording paper P.

  As shown in FIG. 12B, the thickness of the pad 118 in the X direction is thick at the center in the Z direction and thin toward both ends, and the fixing belt 102 on the side facing the baffle main body 158 of the pad 118. The edge 186 in contact with the projection has a convex shape that is swollen at the center in the Z direction. The pad 118 defines the shape of the fixing belt 102 in the Z direction by its edge 186, and the fixing belt 102 is bent by being pressed against the edge 186 of the pad 118.

  As shown in FIG. 12D, the thickness of the baffle main body 158 in the Y direction is thin at the center in the Z direction and increased toward both ends, and the edge of the baffle main body 158 facing the fixing belt 102. Reference numeral 188 denotes a concave shape recessed at the center in the Z direction. That is, the shape of the edge portion 188 of the baffle body portion 158 is a concave shape corresponding to the convex shape of the edge portion 186 of the pad 118. Therefore, although the fixing belt 102 is bent by the edge portion 186 of the pad 118, the gap between the fixing belt 102 and the baffle body portion 158 is set to a predetermined range in the Z direction.

  In FIG. 12, for convenience of explanation, the degree of convexity of the edge 186 of the pad 118, the degree of concaveness of the edge 188 of the baffle main body 158, and the degree of bending of the fixing belt 102 are exaggerated and drawn greatly. .

  As described above, the fixing device 100 according to the present invention contacts the recording paper P while rotating, and fixes the toner image to the recording paper P, and supports the fixing belt 102 rotatably on both sides in the axial direction. A pair of side frames 148, a baffle 140 (or baffle 170) that faces the fixing belt 102 with a gap therebetween and assists the separation of the recording paper P from the fixing belt 102, and a baffle 140 with respect to the side frame 148. A positioning pin 160 (or positioning pin 172) as a positioning portion for positioning (or baffle 170) at least in two different directions along an orthogonal plane orthogonal to the axial direction of the fixing belt 102, a round hole 154, and a long hole 156 are provided. ing. That is, in the fixing device 100, the baffle 140 (or the baffle 170) includes the positioning pin 160 (or the positioning pin 172), the round hole 154, and the long hole 156 with respect to the side frame 148 that rotatably supports the fixing belt 102. The positioning is performed by the positioning unit. Accordingly, the gap between the fixing belt 102 and the baffle 140 (or baffle 170) is set in a predetermined range without requiring any special adjustment work.

  Further, in the baffle 140, the positioning pin 160 includes a small diameter portion 162 that can be fitted into the round hole 154 and the long hole 156, a large diameter portion 164 that cannot be fitted into the round hole 154 and the long hole 156, and a small diameter portion. 162 and a stepped portion 166 formed at the boundary between the large diameter portion 164, and the stepped portion 166 is in contact with the side frame 148 on both sides of the baffle 140. Thereby, the baffle 140 is positioned in the axial direction.

  In the baffle 170, a tie plate 174 is attached by integral molding, and both ends of the tie plate 174 are connected to the side frame 148. Thereby, the change in the interval between the side frames 148 due to the thermal expansion of the baffle 170 is suppressed.

  Further, in the baffle 140 (or baffle 170), the shape of the edge portion 188 facing the fixing belt of the baffle 140 (or baffle 170) contacts the fixing belt 102 from the inside of the fixing belt 102 and the fixing belt 102 This corresponds to the shape of the edge 186 of the pad 118 that defines the shape in the axial direction. Accordingly, the gap between the fixing belt 102 and the baffle 140 (or baffle 170) is set to a predetermined range in the axial direction.

  Further, the image forming apparatus 10 includes the fixing device 100 in which the gap between the fixing belt 102 and the baffle 140 (or baffle 170) is set in a predetermined range. Therefore, the baffle 140 (or the baffle 170) is prevented from coming into contact with the fixing belt 102, and the fixing belt 102 is prevented from being damaged as a cause of image defects. As a result, an image with excellent image quality can be formed on the recording paper P.

  In the fixing device 100 described above, the positioning pin 160 (or positioning pin 172) is formed on the baffle 140 (or baffle 170) as a structure for positioning the baffle 140 (or baffle 170) with respect to the side frame 148. The round holes 154 and the long holes 156 are formed in the side frame 148, but the round holes 154 and the long holes 156 are formed in the baffle 140 (or the baffle 170), and the positioning pins 160 (or the positioning pins are formed in the side frame 148). The pin 172) may be formed. Also, positioning holes are formed in each of the baffle 140 (or baffle 170) and the side frame 148, and pins are inserted into the positioning holes so that the baffle 140 (or baffle 170) is positioned with respect to the side frame 148. Also good.

DESCRIPTION OF SYMBOLS 10 Image forming apparatus 60 Image forming unit 62 Photosensitive body (an example of an image holding body)
64 Intermediate transfer belt (part of transfer device)
72 Developing Device 74 Primary Transfer Roll (Part of Transfer Device)
89 Secondary transfer roll (part of transfer device)
100 fixing device 102 fixing belt (an example of a fixing member)
104 Pressure roll 118 Pad (an example of a specified member)
140 baffle (an example of a peeling assisting member)
148 Side frame (part of support member)
154 Round hole (part of positioning part)
156 Long hole (part of positioning part)
158 Baffle body section 160 Positioning pin (part of positioning section)
162 Small diameter portion 164 Large diameter portion 166 Stepped portion 170 Baffle (an example of a peeling assisting member)
172 Positioning pin (part of positioning part)
174 Tie plate (an example of a metal member)
176 Flat portion 178 Mounting portion 186 Edge portion 188 Edge portion G Toner image N Nip portion

Claims (5)

A fixing member that rotates and contacts the recording medium and fixes the toner image on the recording medium;
A pair of support members that rotatably support the fixing member on both axial sides;
A separation assisting member that faces the fixing member with a gap and assists the separation of the recording medium from the fixing member;
A positioning portion that positions the peeling assisting member with respect to the support member in at least two different directions along an orthogonal plane orthogonal to the axial direction of the fixing member;
A fixing device. The positioning portion includes a positioning hole formed in the support member, and a positioning pin that is formed on both sides of the peeling auxiliary member and is fitted in the positioning hole.
The positioning pin has a small-diameter portion that can be fitted into the positioning hole, a large-diameter portion that cannot be fitted into the positioning hole, and a step portion formed at a boundary between the small-diameter portion and the large-diameter portion. And
The fixing device according to claim 1, wherein the stepped portion is in contact with the support member on both sides of the peeling assisting member. The peeling auxiliary member is formed from a resin material and has a metal member attached by integral molding,
The fixing device according to claim 1, wherein both ends of the metal member are fixed to the support member. The fixing member is an annular belt having flexibility,
The shape of the edge of the peeling assisting member facing the belt corresponds to the shape of a defining member that contacts the belt from the inside of the belt and defines the shape of the belt in the axial direction. 4. The fixing device according to claim 1. An image carrier on which an electrostatic latent image is formed;
A developing device for developing the electrostatic latent image formed on the image carrier with toner;
A transfer device for transferring the toner image developed by the developing device to a recording medium;
The fixing device according to claim 1, wherein the toner image transferred to the recording medium is fixed to the recording medium.
An image forming apparatus comprising:

Images