JP2020052346A - Fixation device and conveyance device - Google Patents

Abstract

To suppress a variation in location of a nip part due to a manufacturing error of each nip part formation member or repetition of a nip condition and nip release condition.SOLUTION: A fixation device 8 comprises: a rotor (heating roller 81) that is heated by a heater 82; an endless belt 83; an upstream nip formation member X that forms an upstream nip part NPu across the endless belt 83 between the rotor and the upstream nip formation member; a first regulation member (upstream wall 186B) that regulates a movement of the upstream nip formation member X; a first urging member (leaf spring S5) that urges the upstream nip formation member X toward the first regulation member; a downstream nip formation member 85 that is arranged on a downstream side in a movement direction with respect to the upstream nip formation member X, and forms a downstream nip part NPd across the endless belt 83 between the rotor and the downstream nip part formation member; a second regulation member (downstream wall 86C) that regulates a movement of the downstream nip formation member 85; and a second urging member (leaf spring S5) that urges the downstream nip formation member 85 toward the second regulation member.SELECTED DRAWING: Figure 2

Description

  The present invention relates to a fixing device including an endless belt and a conveyance device.

  2. Description of the Related Art Conventionally, as a belt-type fixing device, it has been proposed to dispose both in a state where a gap exists between an upstream pad and a downstream pad in order to suppress generation of wrinkles on a recording medium such as an envelope. (See Patent Document 1). Specifically, this technique includes an upstream pad that contacts the endless belt, a support plate that supports the upstream pad, and a holder that supports the support plate.

  The holder integrally has a downstream pad that contacts the endless belt. Then, by positioning the support plate in the concave portion formed in the holder, the upstream pad is positioned relative to the downstream pad in the moving direction of the endless belt in the nip portion.

JP 2010-231008 A

  However, if there is a gap between the upstream pad and the downstream pad, or between the upstream pad and the holder, a variation in the fixing nip region occurs due to a manufacturing error of the upstream pad itself or an attachment error with the support plate. This may adversely affect the performance and the transportability of the recording medium. In particular, by repeatedly performing the operation (nip state / nip release state) of contacting / separating the heating roller and the endless belt, the position of each pad in the moving direction of the endless belt is varied, and the fixing property and the recording medium It may adversely affect the transportability and the like.

  In view of the above, an object of the present invention is to suppress variations in the position of each nip portion due to a manufacturing error of each pad (nip forming member) and repetition of a nip state and a nip release state.

  In order to solve the above problem, a fixing device according to the present invention includes a heater, a rotating body heated by the heater, an endless belt, and an upstream nip portion sandwiching the endless belt between the rotating body. An upstream nip forming member, a first regulating member that contacts the upstream nip forming member and regulates the movement of the upstream nip forming member in the moving direction of the endless belt in the upstream nip portion, and in the moving direction, A first urging member for urging the upstream nip forming member toward the first restricting member to bring the upstream nip forming member into contact with the first restricting member; and moving the upstream nip forming member relative to the upstream nip forming member. A downstream nip forming member that is arranged on the downstream side in the direction and forms a downstream nip portion with the endless belt interposed between the rotating body and the downstream nip forming member, A second regulating member that regulates the movement of the downstream nip forming member in the moving direction, and urges the downstream nip forming member toward the second regulating member in the moving direction to move the downstream nip forming member. A second urging member that comes into contact with the second regulating member.

  According to this configuration, since each nip forming member is urged against each regulating member to come into contact therewith, the position of each nip portion can be determined regardless of manufacturing errors of the nip forming members and repetition of the nip state and the nip release state. Can be stabilized.

  Further, the first urging member and the second urging member may be integrally formed.

  According to this, the number of components can be reduced, and the cost can be reduced.

  The first regulating member is arranged on the upstream side in the moving direction with respect to the upstream nip forming member, and the second regulating member is arranged on the downstream side in the moving direction with respect to the downstream nip forming member. It may be.

  According to this, for example, one compression coil spring or the like can be used as the first urging member and the second urging member, and the apparatus can be simplified.

The apparatus further includes a holder for supporting the upstream nip forming member and the downstream nip forming member, wherein the first urging member and the second urging member are formed by a single leaf spring, A first arm portion that contacts the downstream nip forming member, a second arm portion that contacts the upstream nip forming member, and a base portion that connects the first arm portion and the second arm portion. A holder that supports the upstream nip forming member and the downstream nip forming member, and is located between the upstream nip forming member and the downstream nip forming member in the moving direction; A protruding portion that protrudes in the width direction of
The protruding portion may be configured to contact the base portion to restrict the movement of the leaf spring.

  According to this, it is possible to suppress the leaf springs serving as the first urging member and the second urging member from coming off the upstream nip forming member and the downstream nip forming member.

  The first regulating member is arranged on the downstream side in the moving direction with respect to the upstream nip forming member, and the second regulating member is arranged on the upstream side in the moving direction with respect to the downstream nip forming member. It may be.

  According to this, for example, one tension coil spring or the like can be used as the first urging member and the second urging member, and the apparatus can be simplified.

  The first regulating member is arranged on the downstream side in the moving direction with respect to the upstream nip forming member, and the second regulating member is arranged on the downstream side in the moving direction with respect to the downstream nip forming member. It may be.

  According to this, it is possible to suppress the nip forming member from moving against the urging force of the spring member due to friction with the endless belt.

  Further, the upstream nip forming member has a first pressing pad sandwiching the endless belt between the rotating body and a first pressing pad which is harder than the first pressing pad and to which the first pressing pad is fixed. A fixing member, wherein the downstream nip forming member has a second pressing pad sandwiching the endless belt between the rotating body and the second pressing pad, the second pressing pad being harder than the second pressing pad. A fixed second fixing member, wherein the first urging member urges the first fixing member, and the second urging member urges the second fixing member. .

  According to this, by urging each fixing member harder than each pressure pad by each urging member, the position of each pressure pad, that is, the position of each nip portion can be further stabilized.

  Further, the first urging member is disposed at an interval from the first pressure pad in the width direction of the endless belt, and the second urging member is disposed in the width direction of the endless belt in the width direction of the endless belt. 2 It may be arranged at a distance from the pressure pad.

  According to this, since each of the urging members is arranged at an interval in the width direction from each of the pressing pads, the operation of attaching each of the urging members can be easily performed.

  Further, the first urging member and the second urging member may be leaf springs.

  According to this, for example, when the first urging member and the second urging member are integrally formed, the first urging member and the second urging member are easily formed integrally by one leaf spring.

  The apparatus may further include a holder that supports the upstream nip forming member and the downstream nip forming member, and the first restricting member and the second restricting member may be integrally formed with the holder.

  According to this, the number of components can be reduced, and the cost can be reduced.

  The upstream nip forming member includes a first pressure pad that sandwiches the endless belt with the rotating body, and the downstream nip forming member includes a second pressing pad that sandwiches the endless belt with the rotating body. A pressure pad, wherein the holder is disposed upstream of the first pressure pad in the movement direction, and an upstream wall facing the first pressure pad in the movement direction; A downstream wall that is arranged on the downstream side in the moving direction with respect to the pressure pad and that faces the second pressure pad in the moving direction, and an interval in the moving direction from the upstream wall to the downstream wall is: A configuration in which the length of the upstream nip forming member in the moving direction and the length of the downstream nip forming member in the moving direction are added may be larger.

  According to this, the work of attaching each nip forming member to the holder can be easily performed.

  The present invention is not limited to the fixing device, and may be applied to a transport device having an endless belt that transports a recording medium to and from a rotating body.

  ADVANTAGE OF THE INVENTION According to this invention, the dispersion | variation of the position of each nip part by manufacturing error of each nip formation member, or a repetition of a nip state / nip release state can be suppressed.

FIG. 1 is a sectional view showing a laser printer according to an embodiment of the present invention. FIG. 3 is a cross-sectional view illustrating a fixing device. It is sectional drawing which shows a pressurizing unit. FIG. 3 is an exploded perspective view showing a pressure unit. It is a perspective view which shows a pressurization unit. It is sectional drawing which shows the pressurizing unit which concerns on a 1st modification. It is a perspective view showing the pressurizing unit concerning a 1st modification. It is sectional drawing which shows the pressurizing unit which concerns on a 2nd modification. It is a perspective view showing the pressurizing unit concerning a 2nd modification. It is sectional drawing (a) and the top view (b) which show the pressurizing unit which concerns on a 3rd modification. It is sectional drawing (a) which shows the pressurizing unit which concerns on a 4th modification, and perspective view (b) which shows the structure around a compression coil spring. It is sectional drawing which shows the pressurization unit which concerns on a 5th modification. It is sectional drawing (a) which shows the pressurizing unit which concerns on a 6th modification, and is a perspective view (b) which shows the structure around a leaf spring. It is sectional drawing (a) which shows the pressurizing unit which concerns on a 7th modification, and is a perspective view (b) which shows the structure around a leaf spring.

  Next, an embodiment of the present invention will be described in detail with reference to the drawings as appropriate. In the following description, the direction is “front” on the left side in FIG. 1, “rear” on the right side in FIG. 1, “left” on the rear side in FIG. The side is "right". Further, the up-down direction toward the paper surface is referred to as “up-down”.

  As shown in FIG. 1, the laser printer 1 mainly includes a paper feed unit 3, an exposure device 4, a process cartridge 5, and a fixing device 8 in a housing 2.

  The paper feed unit 3 is provided at a lower portion in the housing 2 and mainly includes a paper feed tray 31 that stores paper S as an example of a recording medium, a paper pressing plate 32, and a paper feed mechanism 33. I have. The sheet S stored in the sheet feeding tray 31 is moved upward by the sheet pressing plate 32 and is supplied to the process cartridge 5 by the sheet feeding mechanism 33.

  The exposure device 4 is disposed at an upper part in the housing 2 and includes a light source device (not shown), a polygon mirror, a lens, a reflecting mirror, and the like, which are omitted from reference numerals. The exposure device 4 exposes the surface of the photosensitive drum 61 by performing high-speed scanning of the surface of the photosensitive drum 61 with a light beam based on image data emitted from the light source device.

  The process cartridge 5 is disposed below the exposure device 4, and is detachable from the housing 2 through an opening formed when the front cover 21 provided on the housing 2 is opened. The process cartridge 5 includes a drum unit 6 and a developing unit 7. The drum unit 6 mainly includes a photosensitive drum 61, a charger 62, and a transfer roller 63. The developing unit 7 is detachable from the drum unit 6, and mainly includes a developing roller 71, a supply roller 72, a layer thickness regulating blade 73, and an accommodating section 74 for accommodating toner. .

  In the process cartridge 5, the surface of the photosensitive drum 61 is uniformly charged by the charger 62, and then is exposed by the light beam from the exposure device 4, so that the photosensitive drum 61 has a static image based on image data. An electrostatic latent image is formed. Further, the toner in the storage section 74 is supplied to the developing roller 71 via the supply roller 72, and enters between the developing roller 71 and the layer thickness regulating blade 73 to form a thin layer having a constant thickness on the developing roller 71. It is carried. The toner carried on the developing roller 71 is supplied from the developing roller 71 to an electrostatic latent image formed on the photosensitive drum 61. Thereby, the electrostatic latent image is visualized, and a toner image is formed on the photosensitive drum 61. Thereafter, the sheet S is conveyed between the photosensitive drum 61 and the transfer roller 63, so that the toner image on the photosensitive drum 61 is transferred onto the sheet S.

  The fixing device 8 is disposed behind the process cartridge 5. The sheet S to which the toner image has been transferred passes through the fixing device 8 so that the toner image is fixed. The sheet S on which the toner image has been fixed is discharged onto the sheet discharge tray 22 by the conveying rollers 23 and 24.

  As shown in FIG. 2, the fixing device 8 includes a heating roller 81 as an example of a rotating body, a heater 82, an endless belt 83, and a pressure unit 84. When one of the heating roller 81 and the pressure unit 84 is urged toward the other, a nip portion NP is formed between the heating roller 81 and the endless belt 83.

  In the following description, the width direction of the endless belt 83 is also simply referred to as the “width direction”, and the moving direction of the endless belt 83 at the nip NP is also simply referred to as the “moving direction”, and the heating roller 81 and the pressing unit 84 ( More specifically, the facing direction in which the nip forming members 85, X) described below face each other is simply referred to as “facing direction”. In the present embodiment, the width direction is along the left-right direction, the moving direction is along the front-back direction, and the opposing direction is along the up-down direction.

  The heating roller 81 is a roller having a cylindrical base, and as an example, is formed by forming a release layer made of a fluororesin on the outer peripheral surface of a base tube made of a metal such as aluminum. The heating roller 81 is driven to rotate counterclockwise in FIG. 2 by inputting a driving force from a motor (not shown). The heating roller 81 is in contact with the outer peripheral surface of the endless belt 83.

  The heater 82 is a heater for heating the heating roller 81, and is disposed radially inside the heating roller 81. As the heater 82, for example, a halogen lamp that emits light when energized and heats the heating roller 81 by radiant heat can be used.

  The endless belt 83 is a cylindrical member and has flexibility. The endless belt 83 is formed, for example, by forming a release layer made of a fluororesin or the like on the outer peripheral surface of a base made of a metal such as stainless steel or a resin such as a polyimide resin. The endless belt 83 is provided so as to be driven to rotate clockwise in FIG. 2 by rotation of the heating roller 81. As a result, the endless belt 83 conveys the paper S between itself and the heating roller 81.

  A lubricant such as grease is applied to the inner peripheral surface 83A of the endless belt 83. Thereby, the slidability between the inner peripheral surface 83A of the endless belt 83 and the pressurizing unit 84 can be improved, so that the endless belt 83 can be favorably rotated.

  The pressure unit 84 includes a downstream nip forming member 85, an upstream nip forming member X, a holder 186 supporting the nip forming members 85 and X, and a plate as an example of a first urging member and a second urging member. It mainly includes a spring S5 and a stay 87 that supports the holder 186. Each nip forming member 85, X (specifically, each pressure pad 88, Y described later) protrudes toward the heating roller 81 from the surface of the holder 186 on the heating roller 81 side while being supported by the holder 186. I have.

  As illustrated in FIG. 3, the downstream nip forming member 85 is a member that forms the downstream nip portion NPd between the heating roller 81 and the endless belt 83 by sandwiching the endless belt 83 between the heating roller 81 and the heating roller 81. , Are located inside the endless belt 83. The upstream nip forming member X is a member that forms an upstream nip portion NPu between the heating roller 81 and the endless belt 83 by sandwiching the endless belt 83 between the heating roller 81 and the upstream nip forming member X. positioned. The upstream nip forming member X is located upstream of the downstream nip forming member 85 in the moving direction. By forming the upstream nip portion NPu and the downstream nip portion NPd by the pressure unit 84 in this way, the sheet S is heated and pressed while passing through the nip portion NP, and the toner image is fixed on the sheet S. Is done.

  In the present embodiment, the upstream nip forming member X is disposed apart from the downstream nip forming member 85 in the moving direction. Therefore, an intermediate nip portion NPi to which the pressure from the pressure unit 84 does not directly act exists between the upstream nip portion NPu and the downstream nip portion NPd. In the intermediate nip portion NPi, although the endless belt 83 contacts the heating roller 81, there is no member that sandwiches the endless belt 83 with the heating roller 81, so that almost no pressure is applied. Therefore, the sheet S passes through the intermediate nip portion NPi while being heated by the heating roller 81 and almost without being pressed. In the present embodiment, a region from the upstream end of the upstream nip portion NPu to the downstream end of the downstream nip portion NPd, that is, an entire region where the outer peripheral surface of the endless belt 83 and the heating roller 81 are in contact with each other is referred to as a nip portion NP. That is, in the present embodiment, the nip portion NP includes a portion to which the pressing force from the pressing pad 88 is not applied.

  The downstream nip forming member 85 includes a second pressing pad 88 that sandwiches the endless belt 83 with the heating roller 81, and a plate-shaped second fixing member 89 to which the second pressing pad 88 is fixed. .

  As shown in FIG. 4, the second pressure pad 88 is a rectangular parallelepiped, and is formed in a long shape that is long in the width direction. The second pressure pad 88 is made of an elastic material such as rubber, so that it can be elastically deformed. Here, since the pressurizing unit 84 has a symmetrical shape, the right side of the pressurizing unit 84 is described in an enlarged manner in FIG. 4, and the left side has the same structure, and the description is omitted. I do.

  The second fixing member 89 is a member made of a material harder than the second pressure pad 88, specifically, a sheet metal. The second fixing member 89 has a base portion 89A to which the second pressure pad 88 is adhered, and an extending portion 89B extending outward from the widthwise end of the base portion 89A in the widthwise direction. .

  The base portion 89A has a length in the moving direction longer than the second pressure pad 88. The area where the second pressure pad 88 is adhered is set at a position away from the upstream end and the downstream end of the base portion 89A. Thus, the second fixing member 89 has a convex portion C that protrudes downstream in the moving direction from the second pressing pad 88 when the second pressing pad 88 is fixed to the base portion 89A. .

  The length of the base 89A in the width direction is longer than that of the second pressure pad 88. The area to which the second pressure pad 88 is adhered is set at a position away from each end in the width direction of the base portion 89A.

  The extending portion 89B has a shorter length in the moving direction than the base portion 89A, and is disposed to be offset to a downstream end of the base portion 89A.

  The upstream nip forming member X includes a first pressure pad Y sandwiching the endless belt 83 between the heating roller 81 and a plate-shaped first fixing member Z to which the first pressure pad Y is fixed. . The first pressure pad Y is configured in substantially the same manner as the second pressure pad 88.

  The first fixing member Z has substantially the same configuration as the second fixing member 89. Specifically, the first fixing member Z is a member made of a material harder than the first pressure pad Y, and more specifically, is formed of a sheet metal. The first fixing member Z has a convex portion C of the second fixing member 89, a convex portion CA substantially similar to the base portion 89A and the extending portion 89B, a base portion ZA and an extending portion ZB. In addition, the extending portion ZB of the first fixing member Z is arranged to be offset to the upstream end of the base portion ZA.

  Holder 186 is made of resin or metal. The holder 186 includes a base 186A, an upstream wall 186B as an example of a first regulating member, a downstream wall 86C as an example of a second regulating member, a first stay engaging wall 86E, and a second stay engaging wall 86F. And That is, in the present embodiment, the first regulating member and the second regulating member are integrally formed with the holder 186. The base 186A is a plate-like portion having a support surface FS orthogonal to the facing direction, and is formed in a long shape that is long in the width direction. The support surface FS slidably supports the fixed members 89 and Z in the movement direction.

  As shown in FIG. 2, the upstream wall 186B protrudes from the upstream end in the moving direction of the base 186A in a direction approaching the heating roller 81. The surface on the upstream side in the movement direction of the upstream wall 186B is a curved surface that guides the inner peripheral surface 83A of the endless belt 83. The upstream wall 186B is disposed on the upstream side in the movement direction with respect to the first pressure pad Y in a state where the upstream nip forming member X is attached to the holder 186. The upstream wall 186B faces the first pressure pad Y in the moving direction.

  The downstream wall 86C protrudes from the downstream end in the movement direction of the base 186A in a direction approaching the heating roller 81. The downstream surface of the downstream wall 86C in the moving direction is a curved surface that guides the inner peripheral surface 83A of the endless belt 83. The downstream wall 86C is arranged on the downstream side in the movement direction with respect to the second pressure pad 88 when the downstream nip forming member 85 is attached to the holder 186. The downstream wall 86C faces the second pressure pad 88 in the moving direction.

  As shown in FIGS. 3 and 4, the downstream wall 86 </ b> C has, on the upstream side in the movement direction, a contact surface FT that contacts the second pressure pad 88, and a concave portion G recessed from the contact surface FT toward the downstream side in the movement direction. have. The contact surface FT is a surface that contacts the second pressure pad 88 in the moving direction, and is orthogonal to the moving direction and faces upstream in the moving direction.

  The distance in the movement direction from the contact surface FT to the upstream wall 186B (the contact surface FTA described later) is larger than the sum of the lengths of the fixed members 89, Z in the movement direction of the base portions 89A, ZA. I have. This makes it easy to place the base parts 89A and ZA on the support surface FS between the upstream wall 186B and the downstream wall 86C.

  The concave portion G is a groove into which the convex portion C of the second fixing member 89 can enter, and is formed so as to penetrate the downstream wall 86C in the width direction. The length of the concave portion G in the moving direction is longer than the length of the convex portion C in the moving direction. In other words, the depth of the concave portion G is larger than the protrusion amount of the convex portion C in the moving direction from the second pressure pad 88.

  The side surface of the concave portion G opposite to the heating roller 81 is formed to be flush with the support surface FS of the base 186A. Note that the side surface of the concave portion G opposite to the heating roller 81 may be located at a position farther from the heating roller 81 than the support surface FS.

  The upstream wall 186B has, on the downstream side in the movement direction, a contact surface FTA that contacts the first pressure pad Y, and a concave portion GA that is recessed from the contact surface FTA toward the upstream side in the movement direction. The contact surface FTA is a surface that contacts the first pressure pad Y in the moving direction, and is orthogonal to the moving direction and faces downstream in the moving direction.

  The concave portion GA is a groove into which the convex portion CA of the first fixing member Z can enter, and is formed so as to penetrate the upstream wall 186B in the width direction. The relationship between the depth of the concave portion GA and the amount of protrusion of the convex portion C in the moving direction is the same as the relationship between the concave portion G and the convex portion C.

  The base 186A has a recess CP that is recessed from the end face in the width direction, and a protrusion PP that is disposed in the recess CP and protrudes in the width direction.

  The space inside the concave portion CP is a space where the leaf spring S5 is arranged. The protruding portion PP is a portion for restricting the leaf spring S5 from moving upward.

  The leaf spring S5 is made of metal or resin. The leaf spring S5 is arranged at an interval from each of the pressure pads 88, Y in the width direction. The leaf spring S5 has a base portion S51, a first arm portion S52, and a second arm portion S53. The base part S51 is a part for connecting the two arm parts S52 and S53. The base part S51 is arranged below the protruding part PP.

  The first arm portion S52 is a portion that engages with the extending portion 89B of the second fixing member 89. The first arm portion S52 extends obliquely from the end on the downstream side in the movement direction of the base portion S51 toward the downstream side in the movement direction and upward with respect to the base portion S51.

  The second arm portion S53 is a portion that engages with the extending portion ZB of the first fixing member Z. The second arm portion S53 extends obliquely with respect to the base portion S51 from the end of the base portion S51 on the upstream side in the movement direction toward the upstream side in the movement direction and upward.

  The leaf spring S5 is arranged between the extending portion 89B of the second fixing member 89 and the extending portion ZB of the first fixing member Z in a compressed state. Thereby, the leaf spring S5 urges the second fixing member 89 toward the downstream wall 86C and urges the first fixing member Z toward the upstream wall 186B in the moving direction. That is, in this embodiment, the second urging member for urging the second fixing member 89 and the first urging member for urging the first fixing member Z are integrally formed as one leaf spring S5. I have.

  When the leaf spring S5 is compressed between the extending portion 89B of the second fixing member 89 and the extending portion ZB of the first fixing member Z, the leaf spring S5 moves upward by its own returning force. try to. However, since the upward movement of the leaf spring S5 is regulated by the contact of the base portion S51 of the leaf spring S5 with the protruding portion PP, the leaf spring S5 comes off the second fixing member 89 and the first fixing member Z. That has been suppressed.

  The first stay engaging wall 86 </ b> E is a wall that engages with an end of the stay 87 on the side of the heating roller 81 of an upstream side wall 87 </ b> B (see FIG. 2), which will be described later. Is provided. Each first stay engaging wall 86E protrudes from the base 186A toward the stay 87.

  The second stay engaging wall 86F is a wall that engages with an end of the stay 87 on the side of the heating roller 81 on a downstream side wall 87C (see FIG. 2) described later, and has two walls that sandwich the downstream side wall 87C in the moving direction. Is provided. Each second stay engaging wall 86F protrudes from the base 186A toward the stay 87.

  As shown in FIG. 2, the stay 87 is made of resin or metal. The stay 87 is formed in a U-shape in cross section, and has a base wall 87A, an upstream side wall 87B, and a downstream side wall 87C. The base wall 87A is a plate-shaped portion having a surface orthogonal to the facing direction, and is formed in a long shape that is long in the width direction.

  The upstream side wall 87B extends from the upstream end of the base wall 87A toward the holder 186. The downstream side wall 87C extends from the downstream end of the base wall 87A toward the holder 186.

Next, the operation and effect of the fixing device 8 according to the present embodiment will be described.
As shown in FIG. 3, in the nip state where the endless belt 83 is sandwiched between the heating roller 81 and the nip forming members 85 and X, the fixing members 89 and Z are fixed to the walls 86C and 186B by the leaf spring S5. By being urged toward, the respective pressure pads 88, Y contact the respective walls 86C, 186B, and the movement of the respective nip forming members 85, X is regulated. Also, in a nip release state in which the endless belt 83 is not sandwiched between the heating roller 81 and the nip forming members 85 and X, similarly, the pressure pads 88 and Y contact the walls 86C and 186B, respectively. The movement of the nip forming members 85 and X is regulated. For this reason, even if the nip state and the nip release state are repeated, the positions of the nip forming members 85 and X with respect to the holder 186 can be kept constant. The position of the entire nip portion NP can be stabilized. Further, even if a manufacturing error of each of the nip forming members 85 and X, for example, a mounting error when bonding each of the pressing pads 88 and Y to each of the fixing members 89 and Z occurs, each pressing force of the leaf spring S5 causes each pressing force. Since the pressure pads 88, Y contact the walls 86C, 186B, the positions of the pressure pads 88, Y with respect to the holder 186 can be kept constant, and the positions of the nip portions NPu, NPd can be stabilized. .

  Further, since the first urging member and the second urging member are integrally formed as one leaf spring S5, the number of parts can be reduced, and the cost can be reduced.

As described above, according to the present embodiment, the following effects can be obtained in addition to the effects described above.
Since the fixing members 89, Z harder than the pressing pads 88, Y are urged by the leaf spring S5, the positions of the pressing pads 88, Y, that is, the positions of the nip portions NPu, NPd are more stabilized. be able to.

  Since the convex portions C and CA of the fixing members 89 and Z enter the concave portions G and GA formed on the walls 86C and 186B, it is possible to prevent the nip forming members 85 and X from coming off the holder 186. it can.

  By making the length of the concave portions G and GA in the moving direction longer than the length of the convex portions C and CA in the moving direction, the tips of the convex portions C and CA do not contact the bottom surfaces of the concave portions G and GA. Can be efficiently used as a force for pressing the pressure pads 88, Y against the contact surfaces FT, FTA.

  Since the leaf springs S5 are arranged at an interval in the width direction from each of the pressure pads 88 and Y, the work of attaching the leaf springs S5 can be easily performed.

  Note that the present invention is not limited to the above embodiment, but can be used in various forms as exemplified below. In the following description, members having substantially the same structure as those of the above-described embodiment are denoted by the same reference numerals, and description thereof will be omitted.

  In the embodiment, the leaf spring S5 is exemplified as the first urging member and the second urging member, but the present invention is not limited to this, and the first urging member and the second urging member may be made of heat-resistant rubber or the like. It may be.

  The configuration in which the first urging member and the second urging member are integrated is not limited to the above embodiment. For example, the first urging member and the second urging member may be integrally formed as a leaf spring S6 as shown in FIGS.

  Specifically, the leaf spring S6 is made of metal or resin. The leaf spring S6 has a base portion S61, a first spring portion S62, a second spring portion S63, and a fixed portion S64. The base part S61 is a part for connecting the two spring parts S62 and S63. The base part S61 is arranged below the protruding part PP.

  The first spring portion S62 is a portion that urges the second fixing member 89 toward the downstream wall 86C. The first spring portion S62 is formed in a U shape in a sectional view that opens downward. The first spring portion S62 extends upward from the downstream end of the base portion S61, and then curves downward in an arc shape and extends downward. A portion of the first spring portion S62 arranged on the downstream side extends below the base portion S61. The first spring portion S62 is disposed between the second fixing member 89 and the protruding portion PP in a state where the first spring portion S62 is compressed in the moving direction. The first spring portion S62 is an example of a second biasing member.

  The second spring portion S63 is a portion that urges the first fixing member Z toward the upstream wall 186B. The second spring portion S63 is formed in a U shape in a sectional view that opens downward. The second spring portion S63 extends upward from the upstream end of the base portion S61, and then curves downward in an arc shape and extends downward. The second spring portion S63 is disposed between the first fixing member Z and the protruding portion PP in a state where the second spring portion S63 is compressed in the moving direction. The second spring portion S63 is an example of a first biasing member.

  The fixing part S64 is a part fixed to the holder 186. The fixing portion S64 protrudes downstream from the lower end of the first spring portion S62. The downstream wall 86C has a concave portion CP1 in which the fixing portion S64 is fitted. Also in this embodiment, the leaf spring S6 can urge the downstream nip forming member 85 toward the downstream wall 86C and urge the upstream nip forming member X toward the upstream wall 186B.

  Further, a compression coil spring S7 as shown in FIG. 8 or FIG. 9 may be arranged between the second fixing member 89 and the first fixing member Z in a contracted state. The compression coil spring S7 is an example of a first urging member and an example of a second urging member. Even in this case, the downstream nip forming member 85 can be urged toward the downstream wall 86C and the upstream nip forming member X can be urged toward the upstream wall 186B by the compression coil spring S7. In this embodiment, since the above-described protrusion PP is not required, the structure of the holder 186 may be a structure having no protrusion PP. In order to hold the compression coil spring S7 between the fixing members 89 and Z, the fixing members 89 and Z may be provided with protrusions C3 and C4 that enter the space radially inside the compression coil spring S7. .

  In the above-described embodiment, the two nip forming members 85 and X are urged in directions away from each other, but the present invention is not limited to this. For example, as shown in FIGS. 10A and 10B, the two nip forming members 585 and X1 may be urged in directions approaching each other.

  Specifically, in this embodiment, the downstream nip forming member 585 includes a second pressure pad 88 similar to that of the above-described embodiment, and a second fixing member 589 having a structure slightly different from that of the above-described embodiment. The second fixing member 589 includes a base 89A and an extension 89B substantially similar to those of the above-described embodiment, except that the extension 89B is arranged to be offset to an upstream end of the base 89A. The form is different.

  The upstream nip forming member X1 includes a first pressure pad Y similar to that of the above-described embodiment, and a first fixing member Z1 having a structure slightly different from that of the above-described embodiment. The first fixing member Z1 includes a base portion ZA and an extension portion ZB substantially similar to those of the above-described embodiment, except that the extension portion ZB is arranged to be offset to the downstream end of the base portion ZA. The form is different.

  The protruding portion PP1 protrudes upward from the support surface FS of the holder 186, and extends from one end to the other end in the width direction of the holder 186. The projecting portion PP1 has a concave portion GB into which the upstream end of the second fixing member 589 enters, and a concave portion GC into which the downstream end of the first fixing member Z1 enters. When the second pressing pad 88 is in contact with the protrusion PP1, the second pressing pad 88 is moved relative to the second fixing member 589 so that the upstream end of the second fixing member 589 is separated from the bottom of the recess GB. Are located. Further, in a state where the first pressure pad Y is in contact with the protruding portion PP1, the first pressure pad is provided to the first fixing member Z1 such that the downstream end of the first fixing member Z1 is separated from the bottom of the concave portion GC. Y is arranged.

  The two nip forming members 585, X1 are urged by the leaf spring S8 toward the protrusion PP1. Here, the protruding portion PP1 is an example of a first regulating member and a second regulating member. The protrusion PP1 is arranged on the downstream side in the moving direction with respect to the upstream nip forming member X1, and is arranged on the upstream side in the moving direction with respect to the downstream nip forming member 585. In this embodiment, the first regulating member and the second regulating member are integrally formed as one protruding portion PP1, but the present invention is not limited to this, and the first regulating member and the second regulating member may be integrated. It may be configured separately.

  The leaf spring S8 has a base portion S81, a first spring portion S82, and a second spring portion S83.

  The base part S81 is a part for connecting the two spring parts S82 and S83. The base portion S81 includes a long portion extending in the moving direction, a portion extending obliquely upward and downstream from the downstream end of the long portion, and a portion extending upstream from the upstream end of the long portion. A portion extending obliquely upward. The base part S81 is arranged below the protruding part PP1.

  The first spring portion S82 is a portion that urges the second fixing member 589 toward the protruding portion PP1. The first spring portion S82 is formed in a U shape in a sectional view that opens downward. The first spring portion S82 extends upward from the downstream end of the base portion S81, and then curves downward in an arc shape and extends downward. The first spring portion S82 is arranged between the second fixing member 589 and the downstream wall 86C while being compressed in the moving direction. The first spring portion S82 is an example of a second biasing member.

  The second spring portion S83 is a portion that urges the first fixing member Z1 toward the protruding portion PP1. The second spring portion S83 is formed to have a U-shape in cross section that opens downward. The second spring portion S83 extends upward from the upstream end of the base portion S81, and then curves downward in an arc shape and extends downward. The second spring portion S83 is arranged between the first fixing member Z1 and the upstream wall 186B while being compressed in the moving direction. The second spring portion S83 is an example of a first biasing member. Also in this embodiment, by pressing the two nip forming members 585 and X1 against the protruding portion PP1, the respective pressure pads 88 and Y can be brought into contact with the protruding portion PP1, so that the same effect as in the above embodiment can be obtained. Obtainable.

  The member for urging the two nip forming members 585 and X1 toward the protruding portion PP1 is not limited to the above-described leaf spring S8. For example, the two nip forming members 685 and X2 may be urged toward the protrusion PP1 by the tension coil spring S9 shown in FIGS. 11 (a) and 11 (b). The extension coil spring S9 is an example of a first urging member and an example of a second urging member.

  Specifically, in this embodiment, the downstream nip forming member 685 includes a second pressure pad 88 similar to the embodiment of FIG. 10 and a second fixing member 689 having a structure slightly different from that of the embodiment of FIG. I have. The second fixing member 689 has a base portion 89A, a first extension portion 689B, and a second extension portion 689C substantially similar to those in the embodiment of FIG.

  The first extending portion 689B is a portion where one end of the extension coil spring S9 is engaged. The first extension portion 689B protrudes from an end in the width direction of the base portion 89A.

  The second extending portion 689C is a portion that prevents one end of the extension coil spring S9 from coming off from the first extending portion 689B. The second extending portion 689C projects upstream and downstream from the tip of the first extending portion 689B.

  The upstream nip forming member X2 includes a first pressure pad Y similar to the embodiment of FIG. 10, and a first fixing member Z2 having a structure slightly different from that of the embodiment of FIG. The first fixing member Z2 has a base portion ZA, a first extension portion Z21, and a second extension portion Z22 substantially similar to those in the embodiment of FIG. The first extending portion Z21 and the second extending portion Z22 have substantially the same structure as the first extending portion 689B and the second extending portion 689C of the second fixing member 689. That is, the other end of the extension coil spring S9 is engaged with the first extension portion Z21, and the second extension portion Z22 suppresses the other end of the extension coil spring S9 from coming off from the first extension portion Z21. Also in this embodiment, the two nip forming members 685 and X2 can be urged toward the protrusion PP1.

  Further, the two nip forming members 785 and X3 may be urged toward the protrusion PP1 by the leaf spring S10 shown in FIG.

  Specifically, in this embodiment, the downstream nip forming member 785 includes a second pressure pad 88 similar to the embodiment of FIG. 11, and a second fixing member 789 having a structure slightly different from that of the embodiment of FIG. I have. The second fixing member 789 includes a base portion 89A, a first extension portion 689B, and a second extension portion 689C (not shown) substantially similar to those in the embodiment of FIG. 11, but the first extension portion 689B includes the base portion 89A. 11 is different from the embodiment in FIG.

  The upstream nip forming member X3 includes a first pressure pad Y similar to the embodiment of FIG. 11, and a first fixing member Z3 having a structure slightly different from that of the embodiment of FIG. The first fixing member Z3 includes a base portion ZA, a first extension portion Z21, and a second extension portion Z22 (not shown) substantially similar to those in the embodiment of FIG. 11, but the first extension portion Z21 is formed of a base portion ZA. 11 is different from the embodiment in FIG.

  The leaf spring S10 is a leaf spring having a substantially U shape in cross section. One end of the leaf spring S10 is engaged with the downstream end of the first extension 689B of the second fixing member 789, and the other end is engaged with the upstream end of the first extension Z21 of the first fixing member Z3. Combine. The leaf spring S10 is an example of a first urging member and an example of a second urging member. Also in this embodiment, the two nip forming members 785 and X3 can be urged toward the protruding portion PP1.

  Further, both of the two nip forming members 885 and X1 may be urged downstream by the leaf spring S11 shown in FIGS. 13 (a) and 13 (b). Specifically, in this embodiment, a nip forming member 885 slightly different in structure from the embodiment in FIG. 4 and an upstream nip forming member X1 substantially similar to the embodiment in FIG. 10 are urged downstream by a leaf spring S11. I have.

  Here, in this embodiment, the downstream wall 86C corresponds to a second regulating member, and the protruding portion PP2 corresponds to a first regulating member. The downstream wall 86C is arranged on the downstream side in the moving direction with respect to the downstream nip forming member 885, and the protrusion PP2 is arranged on the downstream side in the moving direction with respect to the upstream nip forming member X1.

  The downstream nip forming member 885 includes a second pressure pad 88 similar to the embodiment of FIG. 4, and a second fixing member 889 having a structure slightly different from that of the embodiment of FIG. The second fixing member 889 has a base portion 89A and an extending portion 89B substantially similar to those in the embodiment of FIG. Note that the extending portion 89B of the second fixing member 889 is located at a position different from the extending portion ZB of the first fixing member Z1 in the width direction.

  The protruding portion PP2 is formed to be elongated in the width direction similarly to the protruding portion PP1 of FIG. 10, but is different from the protruding portion PP1 of FIG. 10 in that a notch PP21 is formed at the end in the width direction. Are different. The notch PP21 is a notch for avoiding interference of the leaf spring S11 with a base portion S111 described later.

  Further, the projecting portion PP2 has a concave portion GC substantially similar to that of the embodiment of FIG. 10, but is different from the embodiment of FIG. 10 in that it does not have the concave portion GB. The leaf spring S11 has a base portion S111, a first spring portion S112, and a second spring portion S113.

  The first spring portion S112 is a portion for urging the second fixing member 889 toward the downstream wall 86C. The first spring portion S112 is formed in a U shape in a sectional view that opens upward. The first spring portion S112 is arranged between the projecting portion PP2 and the extending portion 89B of the second fixing member 889 in a state where the first spring portion S112 is contracted in the moving direction. The first spring portion S112 is an example of a second biasing member.

  The second spring portion S113 is a portion for urging the first fixing member Z1 toward the projecting portion PP2. The second spring portion S113 is formed in a U-shape in a sectional view that opens upward. The second spring portion S113 is arranged between the upstream wall 186B and the extending portion ZB of the first fixing member Z1 in a state where the second spring portion S113 is contracted in the moving direction. The second spring portion S113 is an example of a first biasing member.

  The base part S111 is a part for connecting the spring parts S112 and S113. The base portion S111 extends from the second spring portion S113 to the downstream side, then extends in the width direction toward the side opposite to the second pressure pad 88, and then extends to the upstream side to form the first spring portion S112. It is connected to.

  According to this embodiment, by pressing the two nip forming members 885 and X1 against the downstream wall 86C and the protrusion PP2, each pressure pad 88 and Y can be brought into contact with the downstream wall 86C and the protrusion PP2. Therefore, the same effect as the above embodiment can be obtained. Further, in this embodiment, since the two nip forming members 885 and X1 are both urged downstream, the nip forming members 885 and X1 move against the urging force of the leaf spring S11 due to friction with the endless belt 83. Can be suppressed.

  Further, both of the two nip forming members 985 and X4 may be urged downstream by the leaf spring S12 shown in FIGS.

  Specifically, in this embodiment, the downstream nip forming member 985 includes a second pressure pad 88 similar to the embodiment of FIG. 13 and a second fixing member 989 having a structure slightly different from that of the embodiment of FIG. I have. The second fixing member 989 has a base portion 89A substantially similar to the embodiment of FIG. 13, and an extending portion 989B extending upstream from the widthwise end of the base portion 89A. A cutout 989C is formed at the upstream end of the extension 989B.

  The upstream nip forming member X4 includes a first pressure pad Y substantially similar to the embodiment of FIG. 13, and a first fixing member Z4 having a structure slightly different from that of the embodiment of FIG. The first fixing member Z4 has a base portion ZA substantially similar to the embodiment of FIG. A notch Z41 is formed at the upstream end of the widthwise end of the base portion ZA. The notch Z41 of the first fixing member Z4 is arranged between the notch 989C of the second fixing member 989 and the first pressing pad Y in the width direction.

  The first fixing member Z4 is disposed below the second fixing member 989. Specifically, the holder 186 includes a first support surface FS1 that movably supports the second fixing member 989 in the moving direction and a second support surface FS2 that movably supports the first fixing member Z4 in the moving direction. Have. The first support surface FS1 is located above the second support surface FS2.

  The leaf spring S12 has a base part S121, a first spring part S122, and a second spring part S123.

  The first spring portion S122 is a portion for urging the second fixing member 989 toward the downstream wall 86C. The first spring portion S122 is formed in a U shape in a sectional view that opens upward. The first spring portion S122 is arranged between the upstream wall 186B and the extending portion 989B (notch 989C) of the second fixing member 989 in a state where the first spring portion S122 is contracted in the moving direction. The first spring portion S122 is an example of a second biasing member.

  The second spring portion S123 is a portion for urging the first fixing member Z4 toward the projecting portion PP2 similar to FIG. In this embodiment, the notch PP21 of the protruding portion PP2 is formed as a notch for avoiding interference with the extending portion 989B of the fixing member 989. The second spring portion S123 is formed in a U shape in a sectional view that opens upward. The second spring portion S123 is arranged between the upstream wall 186B and the first fixing member Z4 (notch Z41) in a state where the second spring portion S123 is contracted in the moving direction. The second spring portion S123 is an example of a first biasing member.

  The base part S121 is a part for connecting the spring parts S122 and S123. The base part S121 connects the upper ends of the spring parts S122 and S123.

  Also in this embodiment, the two nip forming members 885 and X1 can be urged toward the downstream wall 86C and the projecting portion PP2.

  In the above embodiment, both ends of the fixing member are urged by the two urging members. However, the present invention is not limited to this. For example, the center of the fixing member in the width direction is urged by one urging member. May be energized. Further, the first urging member and the second urging member may be configured as separate members.

  In the above-described embodiment, each of the pressing pads 88 and Y is brought into contact with the inner peripheral surface 83A of the endless belt 83. However, the present invention is not limited to this. A sliding sheet may be provided between them.

  In the above-described embodiment, the nip forming members 85 and X are constituted by the pressure pads 88 and Y and the fixing members 89 and Z. However, the present invention is not limited to this. May be configured. Further, the pressure pad may be made of a hard material such as a resin or a metal that does not elastically deform even when pressed. In that case, the pressure pad may be directly urged by the spring member.

  In the above embodiment, the regulating member is provided integrally with the holder 186, but the present invention is not limited to this, and the regulating member may be a member different from the holder, for example.

  In the above-described embodiment, the fixing members 89 and Z are formed in a plate shape. However, the present invention is not limited to this.

  In the embodiment, the configuration for forming the nip portion of the present invention is applied to the fixing device 8, but the present invention is not limited to this, and the configuration of the present invention is also applied to a transport device other than the fixing device. be able to. For example, in a transport device including a transport roller and a paper transport belt that transports a sheet between the transport rollers, the configuration of the present invention may be provided in the paper transport belt.

  In the above embodiment, the pressure pads 88 and Y are rectangular parallelepiped. However, the present invention is not limited to this, and the pressure pad may have any shape.

  In the above embodiment, a halogen lamp is exemplified as the heater 82, but the present invention is not limited to this, and the heater may be, for example, a carbon heater.

  In the above-described embodiment, the heating roller 81 having the heater 82 built therein is exemplified as the rotating body. However, the present invention is not limited to this. For example, an endless heating belt whose inner peripheral surface is heated by the heater may be used. Good. Further, an external heating method in which a heater is disposed outside the rotating body and the outer peripheral surface of the rotating body is heated, or an IH (Induction Heating) method may be used. In addition, a heater may be disposed inside the endless belt, and the rotating body that contacts the outer peripheral surface of the endless belt may be indirectly heated. Further, the rotating body and the endless belt may each have a built-in heater.

  Further, the configuration for forming the nip portion of the present invention is not limited to the fixing device 8 as in the above embodiment, and can be applied to various fixing devices. For example, a fixing roller, a pressure roller that forms a fixing nip between the fixing roller, and a heating unit that contacts the fixing roller with a predetermined nip pressure and heats the fixing roller, include a fixing nip on a sheet. In a fixing device for fixing a toner image on a sheet, the configuration of the present invention may be provided in a heating unit. More specifically, when the heating unit includes an endless belt and a heating member that sandwiches the endless belt between the fixing roller, the heating member may be urged by an urging member.

  In the above-described embodiment, the present invention is applied to the laser printer 1, but the present invention is not limited to this, and the present invention may be applied to other image forming apparatuses, for example, a copier or a multifunction peripheral.

  Further, the components described in the above-described embodiment and the modification may be arbitrarily combined and implemented.

Reference Signs List 8 fixing device 81 heating roller 82 heater 83 endless belt 85 downstream nip forming member 86C downstream wall 186B upstream wall S5 leaf spring X upstream nip forming member

Claims (12)

A heater,
A rotating body heated by the heater;
With an endless belt,
An upstream nip forming member that forms an upstream nip portion with the endless belt interposed between the rotating body and
A first regulating member that contacts the upstream nip forming member and regulates movement of the upstream nip forming member in a moving direction of the endless belt at the upstream nip portion;
A first urging member that urges the upstream nip forming member toward the first regulating member in the moving direction, and brings the upstream nip forming member into contact with the first regulating member;
A downstream nip forming member that is disposed downstream of the upstream nip forming member in the moving direction and forms a downstream nip portion with the endless belt interposed between the rotating body and
A second regulating member that contacts the downstream nip forming member and regulates movement of the downstream nip forming member in the moving direction;
A second urging member that urges the downstream nip forming member toward the second regulating member in the moving direction and brings the downstream nip forming member into contact with the second regulating member. Fixing device.   The fixing device according to claim 1, wherein the first urging member and the second urging member are integrally formed. The first regulating member is disposed on the upstream side in the moving direction with respect to the upstream nip forming member,
The fixing device according to claim 1, wherein the second regulating member is disposed downstream of the downstream nip forming member in the moving direction. 4. Further comprising a holder for supporting the upstream nip forming member and the downstream nip forming member,
The first biasing member and the second biasing member are configured by a single leaf spring,
The leaf spring includes a first arm portion that contacts the downstream nip forming member, a second arm portion that contacts the upstream nip forming member, and a base portion that connects the first arm portion and the second arm portion. And
The holder is located between the base that supports the upstream nip forming member and the downstream nip forming member and the upstream nip forming member and the downstream nip forming member in the moving direction, and has a width from the base to the endless belt. And a projection that projects in the direction,
The fixing device according to claim 3, wherein the protruding portion contacts the base portion to restrict movement of the leaf spring. The first regulating member is disposed on the downstream side in the moving direction with respect to the upstream nip forming member,
The fixing device according to claim 1, wherein the second regulating member is disposed on an upstream side in the moving direction with respect to the downstream nip forming member. The first regulating member is disposed on the downstream side in the moving direction with respect to the upstream nip forming member,
The fixing device according to claim 1, wherein the second regulating member is disposed downstream of the downstream nip forming member in the moving direction. 4. A first pressing pad sandwiching the endless belt between the upstream nip forming member and the rotating body; a first fixing member which is harder than the first pressing pad and to which the first pressing pad is fixed; And
The downstream nip forming member is a second pressing pad that sandwiches the endless belt between the rotating body and a second fixing member that is harder than the second pressing pad and to which the second pressing pad is fixed. And
The first biasing member biases the first fixing member,
7. The fixing device according to claim 1, wherein the second urging member urges the second fixing member. 8. The first biasing member is disposed at an interval from the first pressure pad in a width direction of the endless belt,
The fixing device according to claim 7, wherein the second urging member is arranged at an interval from the second pressure pad in a width direction of the endless belt.   The fixing device according to any one of claims 1 to 8, wherein the first urging member and the second urging member are leaf springs. Further comprising a holder for supporting the upstream nip forming member and the downstream nip forming member,
The fixing device according to claim 1, wherein the first regulating member and the second regulating member are integrally formed with the holder. The upstream nip forming member includes a first pressure pad that sandwiches the endless belt with the rotating body,
The downstream nip forming member includes a second pressure pad that sandwiches the endless belt with the rotating body,
The holder is disposed upstream of the first pressing pad in the moving direction with respect to the first pressing pad, and an upstream wall facing the first pressing pad in the moving direction, and the holder is provided with respect to the second pressing pad. A downstream wall disposed on the downstream side in the moving direction and facing the second pressure pad in the moving direction;
The interval in the moving direction from the upstream wall to the downstream wall is larger than the sum of the length of the upstream nip forming member in the moving direction and the length of the downstream nip forming member in the moving direction. The fixing device according to claim 10, wherein: A rotating body,
An endless belt that conveys a recording medium between the rotating body and
An upstream nip forming member that forms an upstream nip portion with the endless belt interposed between the rotating body and
A first regulating member that contacts the upstream nip forming member and regulates movement of the upstream nip forming member in a moving direction of the endless belt at the upstream nip portion;
A first urging member that urges the upstream nip forming member toward the first restricting member in the moving direction to contact the upstream nip forming member with the first restricting member;
A downstream nip forming member that is disposed downstream of the upstream nip forming member in the moving direction and forms a downstream nip portion with the endless belt interposed between the rotating body and
A second regulating member that contacts the downstream nip forming member and regulates movement of the downstream nip forming member in the moving direction;
A second urging member that urges the downstream nip forming member toward the second regulating member in the moving direction and brings the downstream nip forming member into contact with the second regulating member. Transfer device.

Images