JP5359902B2 - Fixing device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a fixing device capable of adjusting a sheet feeding direction. <P>SOLUTION: The fixing device 100 includes: a cylindrical fixing film 110; a heater (halogen lamp 120) disposed inside the fixing film 110; a nip member (nip plate 130) disposed to come into slide contact with the inner surface of the fixing film 110 and receiving radiant heat from the heater; and a resiliently deformable backup member (pressure roller 150) holding the fixing film between the backup member and the nip member, in a resiliently deformed state, to form a nip portion between the backup member and the fixing film. Then, the fixing device 100 includes an adjustment mechanism configured to move the nip member to a first position and a second position, which are different from each other in the feeding direction of recording sheet (paper P), to adjust the feeding direction of the recording sheet. <P>COPYRIGHT: (C)2011,JPO&amp;INPIT

Description

  The present invention relates to a fixing device that thermally fixes a developer image transferred to a recording sheet.

  As a fixing device used in an electrophotographic image forming apparatus, a nip plate that forms a nip portion between a cylindrical fixing film, a heater disposed in the fixing film, and a pressure roller via the fixing film (For example, refer to Patent Document 1). In this fixing device, the developer image on the paper is thermally fixed while conveying the paper (recording sheet) between the fixing film supported by the nip plate and the pressure roller (nip portion).

JP 2008-233886 A

  By the way, in the fixing device described above, the curl amount (the degree to which the paper is rounded about the axis along the paper width direction due to fixing) differs depending on the type of paper such as plain paper or thick paper. Since the discharge direction of the paper discharged from the apparatus changes, it is necessary to adjust the paper discharge direction (conveyance direction). In addition, normal discharge that is sent from the fixing device to a discharge tray on the upper surface of the image forming apparatus, straight discharge that discharges paper onto the rear cover from the opening formed in the rear wall of the image forming apparatus by opening the rear cover, Even when executing the above, it has been desired to adjust the paper discharge direction.

  SUMMARY An advantage of some aspects of the invention is that it provides a fixing device capable of adjusting the conveyance direction of a sheet (recording sheet).

The present invention that solves the above-described problems is provided with a cylindrical fixing film, a heating element disposed inside the fixing film, and a sliding contact with an inner surface of the fixing film, and receives radiant heat from the heating element. A fixing device comprising: a nip member; and a backup member that is elastically deformable and forms a nip portion with the fixing film by sandwiching the fixing film with the nip member in an elastically deformed state. there are, the nip member, by moving to the second position in the transport direction odor of the recording sheet Te first position and the first conveying direction upstream side of a position, the said first position an adjusting mechanism for adjusting a conveying direction of the recording sheet by the backup member different shapes in the second position, the nip member when the thickness of the recording sheet is equal to or less than a predetermined value A controller that controls the adjustment mechanism to dispose the nip member at the second position when the thickness of the recording sheet is greater than a predetermined value. The amount of protrusion from the backup member to the upstream side in the conveyance direction is larger when the nip member is located at the second position than when the nip member is located at the first position .

  According to the present invention, for example, when the surface of the nip member on the backup member side is a curved surface, when the nip member is moved to the first position and the second position that are different in the recording sheet conveyance direction, The backup member is deformed into a different shape. Thereby, it is possible to change the conveyance direction of the recording sheet (for example, the discharge direction of the recording sheet discharged from the nip portion between the nip member and the backup member).

  According to the present invention, the conveyance direction of the recording sheet can be adjusted.

1 is a diagram illustrating a schematic configuration of a laser printer including a fixing device according to an embodiment of the present invention. 1 is a diagram illustrating a schematic configuration of a fixing device according to an embodiment of the present invention. It is a perspective view of a halogen lamp, a nip plate, a reflecting plate, and a stay. It is the figure which looked at the nip plate, the reflecting plate, and the stay from the conveyance direction. They are the perspective view (a) which looked at the guide member from the upper side, the perspective view (b) which looked at the guide member which attached the stay from the lower side, and the bottom view (c). FIG. 6 is a side view of the fixing device when the nip plate is located at a first position as viewed from the left side. It is a side view which shows the state which released the nip pressure when the nip plate is located in the 1st position. It is a side view which shows the state which moved the nip board to the 2nd position. It is a side view which shows the state which returned the nip pressure when the nip plate was located in the 2nd position. 4A and 4B are explanatory diagrams illustrating a relationship between a nip plate and a pressure roller when changing a paper discharge direction. It is explanatory drawing (a), (b) which shows the form which formed the lower surface of the nip plate pressed by a pressure roller in the curved surface form which has the same curvature. It is a side view which shows the form which drives an upper housing | casing with an actuator. It is a flowchart which shows operation | movement of the control apparatus of FIG.

  Next, embodiments of the present invention will be described in detail with reference to the drawings as appropriate. In the following description, the schematic configuration of the laser printer 1 (image forming apparatus) including the fixing device 100 according to the embodiment of the present invention will be described first, and then the detailed configuration of the fixing device 100 will be described.

<Schematic configuration of laser printer>
As shown in FIG. 1, the laser printer 1 includes a main body housing 2 in which a paper sheet 3 as an example of a recording sheet is fed, an exposure device 4, and a toner image (developer) on the paper P. And the fixing device 100 for thermally fixing the toner image on the paper P.

  In the following description, the direction will be described with reference to the user who uses the laser printer. That is, the right side in FIG. 1 is “front”, the left side is “rear”, the front side is “left”, and the back side is “right”. Also, the vertical direction in FIG.

  The paper feed unit 3 is provided in the lower part of the main body housing 2, and includes a paper feed tray 31 that accommodates the paper P, a paper pressing plate 32 that lifts the front side of the paper P, a paper feed roller 33, and a paper feed pad 34. And paper dust removing rollers 35 and 36 and a registration roller 37 are mainly provided. The paper P in the paper feed tray 31 is brought close to the paper feed roller 33 by the paper pressing plate 32 and separated one by one by the paper feed roller 33 and the paper feed pad 34, and the paper dust removing rollers 35, 36 and the registration roller 37. Then, it is conveyed toward the process cartridge 5.

  The exposure apparatus 4 is arranged at the upper part in the main body housing 2 and mainly includes a laser light emitting unit (not shown), a polygon mirror 41 that is rotationally driven, lenses 42 and 43, and reflecting mirrors 44, 45, and 46. In preparation. In the exposure apparatus 4, the laser light (see the chain line) based on the image data emitted from the laser light emitting part is reflected or passed through the polygon mirror 41, the lens 42, the reflecting mirrors 44 and 45, the lens 43 and the reflecting mirror 46 in this order. The surface of the photosensitive drum 61 is scanned at high speed.

  The process cartridge 5 is disposed below the exposure apparatus 4 and is detachably mounted on the main body housing 2 through an opening formed when the front cover 21 provided on the main body housing 2 is opened. Yes. 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 configured to be detachably attached to the drum unit 6, and includes a developing roller 71, a supply roller 72, a layer thickness regulating blade 73, and a toner that contains toner (developer). The housing part 74 is mainly provided.

  In the process cartridge 5, the surface of the photosensitive drum 61 is uniformly charged by the charger 62 and then exposed by high-speed scanning of the laser light from the exposure device 4, whereby image data is transferred onto the photosensitive drum 61. An electrostatic latent image based on is formed. Further, the toner in the toner container 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 of a certain thickness on the developing roller 71. It is carried on.

  The toner carried on the developing roller 71 is supplied from the developing roller 71 to the electrostatic latent image formed on the photosensitive drum 61. As a result, the electrostatic latent image is visualized and a toner image is formed on the photosensitive drum 61. Thereafter, the paper P is conveyed between the photosensitive drum 61 and the transfer roller 63, whereby the toner image on the photosensitive drum 61 is transferred onto the paper P.

  The fixing device 100 is provided behind the process cartridge 5. The toner image (toner) transferred onto the paper P is thermally fixed onto the paper P by passing through the fixing device 100. The paper P on which the toner image is thermally fixed is discharged onto the paper discharge tray 22 by the transport rollers 23 and 24.

<Detailed configuration of fixing device>
As shown in FIG. 2, the fixing device 100 includes a fixing film 110, a halogen lamp 120 as an example of a heating element, a nip plate 130 as an example of a nip member, a reflection plate 140, and an example of a backup member. A pressure roller 150 and a stay 160 are provided.

  The fixing film 110 is an endless (cylindrical) film having heat resistance and flexibility, and both ends thereof are guided to rotate by guide members 170 described later.

  The halogen lamp 120 is a known heating element that heats the toner on the paper P by heating the nip plate 130 and the fixing film 110. Inside the fixing film 110, a predetermined amount of heat is supplied from the inner surfaces of the fixing film 110 and the nip plate 130. They are arranged at intervals.

  The nip plate 130 is a plate-like member that receives radiant heat from the halogen lamp 120, and is disposed so as to be in sliding contact with the inner surface of the cylindrical fixing film 110. The nip plate 130 transmits the radiant heat received from the halogen lamp 120 to the toner on the paper P through the fixing film 110.

  The nip plate 130 has a thermal conductivity higher than that of a steel stay 160, which will be described later. For example, the nip plate 130 is formed by bending an aluminum plate or the like into a substantially U shape in sectional view. More specifically, the nip plate 130 is bent toward the base portion 131 extending in the front-rear direction (the conveyance direction of the paper P) and upward (the direction from the pressure roller 150 toward the nip plate 130) in a cross-sectional view. The bent portion 132 is mainly included.

  The lower surface (surface on the pressure roller 150 side) of the nip plate 130 bent in a U shape in this way has a flat surface portion 130A having a curvature of 0 and a curved surface portion 130B formed with a curvature larger than 0. It has composition which has.

  Thus, as will be described in detail later, when the nip plate 130 is positioned at the first position shown in FIG. 10A, a portion of the lower surface of the nip plate 130 that is pressed by the pressure roller 150 (specifically, In the nip portion, the curvature of the portion PA1) on the downstream side in the transport direction that affects the discharge direction of the paper P from the fixing device 100 is zero. Further, when the nip plate 130 is positioned at the second position (position of FIG. 10B) upstream of the first position in the transport direction, it is pressed by the pressure roller 150 on the lower surface of the nip plate 130. The curvature of the portion (portion PA2 on the downstream side in the transport direction) has a curvature larger than 0 (a curvature different from that of the portion PA1).

  Note that the inner surface (upper surface) of the base portion 131 may be painted black or provided with a heat absorbing member. According to this, the radiant heat from the halogen lamp 120 can be efficiently absorbed.

  As shown in FIG. 3, the nip plate 130 further includes an insertion portion 133 that extends in a flat plate shape from the right end portion of the base portion 131, and an engagement portion 134 that is formed at the left end portion of the base portion 131. The engaging portion 134 is formed in a U shape in a side view, and an engaging hole 134B is provided in a side wall portion 134A formed by bending upward.

  As shown in FIG. 2, the reflecting plate 140 reflects the radiant heat from the halogen lamp 120 (radiant heat radiated mainly in the front-rear direction and the upward direction) toward the nip plate 130 (the inner surface of the base portion 131). It is a member and is arranged at a predetermined interval from the halogen lamp 120 so as to surround the halogen lamp 120 inside the fixing film 110.

  By collecting the radiant heat from the halogen lamp 120 to the nip plate 130 with such a reflector 140, the radiant heat from the halogen lamp 120 can be used efficiently, and the nip plate 130 and the fixing film 110 can be heated quickly. Can do.

  The reflection plate 140 is formed by curving an aluminum plate or the like in a substantially U shape in cross section, for example, having a high infrared and far infrared reflectance. More specifically, the reflecting plate 140 mainly includes a reflecting portion 141 having a curved shape (substantially U-shaped in cross section) and a flange portion 142 extending from both ends of the reflecting portion 141 along the outer side in the front-rear direction. . In order to increase the thermal reflectance, the reflection plate 140 may be formed using a mirror-finished aluminum plate or the like.

  As shown in FIG. 3, a total of four flange-like locking portions 143 are formed at both ends of the reflection plate 140 in the left-right direction (the width direction of the paper P) (only three are shown). The locking portion 143 is located above the flange portion 142. As shown in FIG. 4, when the nip plate 130, the reflecting plate 140, and the stay 160 are assembled, a plurality of contact portions 163 of the stay 160 described later are provided. It arrange | positions so that it may pinch | interpose (adjacent to the outermost contact part 163A in the left-right direction).

  As a result, even if the reflection plate 140 tries to move left and right due to vibrations when the fixing device 100 is driven, the position of the reflection plate 140 in the left-right direction is restricted by the locking portion 143 coming into contact with the contact portion 163A. The As a result, it is possible to suppress the displacement of the reflecting plate 140 in the left-right direction.

  As shown in FIG. 2, the pressure roller 150 is an elastically deformable member and is disposed below the nip plate 130. The pressure roller 150 forms a nip portion with the fixing film 110 by sandwiching the fixing film 110 with the nip plate 130 in an elastically deformed state.

  The pressure roller 150 is configured to be driven to rotate by a driving force transmitted from a motor (not shown) provided in the main body housing 2, and to rotate with the fixing film 110 (or paper P). The fixing film 110 is driven and rotated by the frictional force.

  The sheet P on which the toner image is transferred is conveyed between the pressure roller 150 and the heated fixing film 110 (nip portion), whereby the toner image (toner) is thermally fixed.

  The stay 160 is a member that secures the rigidity of the nip plate 130 by supporting both end portions 131B of the nip plate 130 (base portion 131) in the front-rear direction via the flange portion 142 of the reflection plate 140. The stay 160 has a shape (substantially U shape in cross section) along the outer surface shape of the reflecting plate 140 (reflecting portion 141) and is disposed so as to cover the reflecting plate 140. Such a stay 160 has relatively high rigidity, for example, is formed by bending a steel plate or the like into a substantially U shape in cross-sectional view.

  At the lower ends of the front wall 161 and the rear wall 162 of the stay 160, as shown in FIG. 3, a plurality of contact portions 163 formed in a substantially comb shape are provided.

  Further, a substantially L-shaped locking portion 165 extending downward and further toward the left is provided at the right end portions of the front wall 161 and the rear wall 162 of the stay 160. Further, a holding portion 167 is provided at the left end of the stay 160 and extends leftward from the upper wall 166 and is bent into a substantially U shape in a side view. Engagement bosses 167B (only one is shown) projecting inward are provided on the inner surfaces of the side wall portions 167A of the holding portion 167.

  As shown in FIGS. 2 and 3, a total of four abutting bosses 168 projecting inward are provided at both ends in the left-right direction of the inner surfaces of the front wall 161 and the rear wall 162 of the stay 160. The abutting boss 168 abuts on the reflecting plate 140 (reflecting portion 141) in the front-rear direction. As a result, even if the reflection plate 140 tries to move back and forth due to vibrations when the fixing device 100 is driven, the position of the reflection plate 140 in the front-rear direction is restricted by contacting the contact boss 168. As a result, it is possible to suppress the displacement of the reflector plate 140 in the front-rear direction.

  Further, supported portions 169 projecting outward in the left-right direction are formed at the upper portions of the left and right ends of the stay 160, and the supported portions 169 are supported by guide members 170 described later.

  When the reflecting plate 140 and the nip plate 130 are assembled to the stay 160 described above, the reflecting plate 140 is first attached to the stay 160 so as to be fitted. Since the abutting boss 168 is provided on the inner surfaces of the front wall 161 and the rear wall 162 of the stay 160, the reflecting plate 140 is temporarily held by the stay 160 when the abutting boss 168 contacts the reflecting plate 140. The

  Thereafter, as shown in FIG. 4, the insertion portion 133 of the nip plate 130 is inserted between the locking portions 165 of the stay 160 to engage the base portion 131 (both end portions 131B) with the locking portions 165, and then Then, the engaging portion 134 (engaging hole 134B) of the nip plate 130 and the holding portion 167 (engaging boss 167B) of the stay 160 are engaged.

  Thereby, the both ends 131 </ b> B of the base portion 131 are supported by the locking portion 165 and the engaging portion 134 is held by the holding portion 167, so that the nip plate 130 is held by the stay 160. In addition, the reflecting plate 140 is held by the stay 160 in a state where the flange portion 142 is sandwiched between the nip plate 130 and the stay 160.

  As a result, even if the reflection plate 140 tries to move up and down due to vibrations when the fixing device 100 is driven, the flange portion 142 is sandwiched between the nip plate 130 and the stay 160 so that the reflection plate 140 is moved in the vertical direction. The position of is regulated. As a result, it is possible to suppress the positional deviation of the reflecting plate 140 in the vertical direction, and to fix the position of the reflecting plate 140 with respect to the nip plate 130.

  The stay 160 that holds the nip plate 130 and the reflection plate 140 and the halogen lamp 120 are directly fixed to the guide member 170 shown in FIG. That is, the guide member 170 integrally supports the nip plate 130, the reflection plate 140, the stay 160, and the halogen lamp 120.

  The guide members 170 are formed of an insulating material such as a resin, and are arranged one by one on both ends of the fixing film 110 to mainly restrict the movement of the fixing film 110 in the left-right direction (axial direction). . Specifically, the guide member 170 includes a restriction surface 171 for restricting the movement of the fixing film 110 in the left-right direction, a suppressing portion 172 for suppressing deformation of the fixing film 110 inward in the radial direction, and both end portions of the stay 160. Is mainly provided with a holding recess 173.

  The suppressing portion 172 is a rib that protrudes inward in the left-right direction from the restriction surface 171 and is formed in a C shape with the opening facing downward. The suppressing portion 172 suppresses deformation inward in the radial direction by entering the fixing film 110. Further, the opening facing the lower side of the suppressing portion 172 serves as an escape portion for inserting the stay 160 into the holding recess 173.

  The holding recess 173 is a groove that opens downward and penetrates inward in the left-right direction. Of the walls that form the holding recess 173, the pair of side walls 174 that face each other in the front-rear direction are shown in FIGS. ), A pair of engagement protrusions 174A are formed. Each engagement protrusion 174A is formed so as to protrude inward from a position away from the bottom surface 173A of the holding recess 173 (see FIG. 5A).

  5B, when the supported portion 169 of the stay 160 is inserted between the bottom surface 173A of the holding recess 173 and the pair of engaging protrusions 174A, the supported portion 169 moves in the vertical direction. Is regulated by the bottom surface 173A of the holding recess 173 and the pair of engaging protrusions 174A. Thereby, it is possible to suppress the positional deviation of the stay 160 in the vertical direction with respect to the guide member 170.

  Further, the edge 160A on the outer side in the left-right direction of the stay 160 is in contact with the inner surface 174B in the left-right direction of the pair of engaging protrusions 174A. As a result, even if the stay 160 tries to move left and right due to vibration or the like when the fixing device 100 is driven, the position of the stay 160 in the left-right direction is restricted by the engagement protrusion 174A coming into contact with the stay 160. As a result, the displacement of the stay 160 in the left-right direction with respect to the guide member 170 can be suppressed.

  Further, the stay 160 is sandwiched between the pair of side walls 174 of the holding recess 173 in the front-rear direction, so that the positional deviation in the front-rear direction is suppressed. As described above, the stay 160 is supported by the guide member 170, whereby the nip plate 130 and the reflection plate 140 are integrally supported by the guide member 170 via the stay 160.

  Further, a fixing portion 175 for fixing the halogen lamp 120 is formed on the outer side of the guide member 170 in the left-right direction so as to protrude outward in the left-right direction. A mounting hole 175A for screwing a bolt B (see FIG. 6) is formed on the lower surface of the fixing portion 175. Then, as shown in FIG. 6, the plate-like terminal 121 at the end portion of the halogen lamp 120 is directly fixed to the lower surface of the fixing portion 175 with a bolt B. The terminal 121 is electrically connected to a power source (not shown) of the main body housing 2 of the laser printer 1 via a flexible wiring.

  The guide member 170 configured as described above is supported by the fixing frame 180 so as to be movable up and down while supporting the nip plate 130 and the like. Further, a support plate 176 extending while being appropriately bent substantially rearward (a cam portion 186 side described later) is fixed to the upper surface of the guide member 170.

  Between the support plate 176 and the upper frame 181 fixed to the upper part of the fixing frame 180, there is a coil spring S that constantly urges the support plate 176 and the guide member 170 downward (on the pressure roller 150 side). Is provided. Thereby, a suitable nip pressure is applied between the nip plate 130 and the pressure roller 150 during printing control.

  The fixing frame 180 is divided into an upper casing 190 and a lower casing 200, and the guide member 170 is movable up and down in a support groove 183 formed in the upper casing 190. It is supported by.

  The upper housing 190 is movable in the front-rear direction while engaging with the lower housing 200 so as not to move in the vertical direction. More specifically, a groove (for example, a T-shaped groove) extending in the front-rear direction is formed in the upper housing 190, and this groove is formed in the lower housing 200 (for example, the lower housing 200). (T-shaped rib) is slidably supported in the front-rear direction. The lower housing 200 supports the pressure roller 150 via a bearing 210 and is fixed to the main body housing 2 (see FIG. 1) of the laser printer 1.

  Further, the upper casing 190 is formed with a positioning recess 191 that opens downward, and an operation piece 192 that is gripped by the user so that the upper casing 190 can be pushed and pulled back and forth. . Further, the lower casing 200 is brought into contact with the front side surface 191A and the rear side surface 191B of the positioning recess 191 so that the upper casing 190 is opposed to the conveyance direction of the paper P (the nip plate 130 and the pressure roller 150 face each other). Positioning protrusions 201 for positioning at different first positions (positions in FIG. 6) and second positions (positions in FIG. 9) in the direction and the direction orthogonal to the rotation axis direction of the fixing film 110 are formed. Has been. Note that the second position is set to a position upstream of the first position in the transport direction.

  That is, in the present embodiment, the divided upper and lower casings 190 and 200 move the nip plate 130 to the first position and the second position, thereby discharging the paper P (conveyance). An adjustment mechanism for adjusting (direction) is configured.

  In addition, a release mechanism CM that releases the nip pressure by moving the nip plate 130 away from the pressure roller 150 is provided on the left and right side walls of the upper casing 190. The release mechanism CM includes an operation lever 184, a rotation shaft 185, and a cam portion 186.

  One end of the operation lever 184 is integrally fixed to a rotation shaft 185 that penetrates the left and right side walls of the upper housing 190, and the rotation shaft 185 is rotatably supported by the upper housing 190.

  The cam portion 186 is integrally fixed to the rotation shaft 185 so as to protrude radially outward from both left and right ends of the rotation shaft 185. Therefore, when the operating lever 184 is rotated and the left and right support plates 176 are pressed upward by the left and right cam portions 186, the left and right guide members 170 resist the urging force of the coil spring S as shown in FIG. Ascending, the nip plate 130 is separated from the pressure roller 150 and the nip pressure is released.

  In this state, when the user grasps the operation piece 192 and pushes the upper casing 190 forward, the upper casing 190 moves from the first position to the second position in the transport direction as shown in FIG. To do. Thereafter, as shown in FIG. 9, when the operation lever 184 is returned to the original position, the cam portion 186 is detached from the left and right support plates 176, and the left and right guide members 170 are lowered by the biasing force of the coil spring S. The nip plate 130 is pressed against the pressure roller 150 to generate a nip pressure. When the cam portion 186 is detached from the support plate 176 and a nip pressure is generated, a sufficient frictional force is generated between the upper housing 190 and the lower housing 200, and the upper housing 190 is moved in the front-rear direction. It doesn't move.

  With the above operation, the nip plate 130 moves from the first position shown in FIG. 10A to the second position shown in FIG. As a result, the part of the lower surface of the nip plate 130 that is pressed by the pressure roller 150 on the downstream side in the transport direction changes from the part PA1 where the curvature is zero to the part PA2 having a curvature larger than 0, so The pressure roller 150 changes to a different shape.

  Therefore, as shown in FIGS. 10A and 10B, the discharge direction of the paper P from the nip portion can be adjusted. Further, the nip width can be changed by changing the pressure roller 150 to a different shape when adjusting the discharge direction of the paper P. When the nip plate 130 is moved from the second position to the first position, the above-described operation may be performed in reverse.

According to the above, the following effects can be obtained in the present embodiment.
When the nip plate 130 is moved in the conveyance direction of the paper P, the pressure roller 150 changes to a different shape, so that the discharge direction of the paper P can be adjusted.

  Since the release mechanism CM for releasing the nip pressure is provided, the nip plate 130 can be smoothly moved in the conveyance direction of the paper P.

In addition, this invention is not limited to the said embodiment, It can utilize with various forms so that it may illustrate below.
In the above embodiment, the nip plate 130 has a lower portion of the lower surface of the nip plate 130 that is pressed by the pressure roller 150 so that the curvature of the downstream portion in the transport direction is different between the first position and the second position. However, the present invention is not limited to this. For example, as shown in FIGS. 11A and 11B, the curvature of the portion (part PA3, PA4) on the downstream side in the transport direction of the part pressed by the pressure roller 150 on the lower surface of the nip plate 130 is The lower surface of the nip plate 130 may be formed in a curved surface so that the curvature is the same at the first position and the second position. Even in this case, the pressure roller 150 can be changed into different shapes at the first position and the second position, so that the discharge direction of the paper P can be adjusted.

  In the above embodiment, the release mechanism CM for releasing the nip pressure is provided. However, the present invention is not limited to this, and the nip plate is not provided as shown in FIG. 12, that is, without releasing the nip pressure. 130 (upper housing 190) may be moved only in the transport direction of the paper P. Also, as shown in FIG. 12, the nip plate 130 (upper housing 190) may be automatically moved in the transport direction of the paper P by a drive source such as the actuator 300.

  In the structure in which the nip plate 130 is automatically moved by the actuator 300 as described above, the position of the nip plate 130 can be changed according to the thickness of the paper P by the control device 400. Specifically, the control device 400 can be configured to follow the flowchart shown in FIG.

  That is, when the control device 400 receives print information output from the personal computer or the like to the laser printer 1 (START), the control device 400 includes information on the thickness of the paper P (for example, paper such as plain paper or postcard) from the print information. Or the like), and it is determined whether or not the thickness of the paper P is larger than a predetermined value (S101).

  When the thickness of the paper P is larger than the predetermined value in step S101 (Yes), the control device 400 is arranged such that the nip plate 130 is disposed at the second position upstream in the transport direction from the first position. The actuator 300 (adjustment mechanism) is controlled (S102). Here, “the actuator 300 is controlled so that the nip plate 130 is arranged at the second position” means that the actuator 300 is located when the nip plate 130 is located at the first position at the time of determination in step S101. Is driven to move the nip plate 130 to the second position, and the actuator 300 is not driven when the nip plate 130 is located at the second position.

  If the thickness of the paper P is equal to or smaller than the predetermined value in step S101 (No), the control device 400 controls the actuator 300 so that the nip plate 130 is disposed at the first position (S103). .

  According to the above, when the thickness of the paper P is larger than the predetermined value, the nip plate 130 is located at the second position (on the upstream side in the transport direction from the first position (position in FIG. 10A)) By moving to the position of FIG. 10B, the amount by which the nip plate 130 protrudes from the pressure roller 150 to the upstream side in the transport direction increases. Therefore, in the case of a thick paper P such as a postcard, the paper P can be heated in advance by the protruding portion of the nip plate 130 before the paper P enters the nip portion, thereby improving the heat fixing property. Can be made.

  In the above embodiment, the discharge direction of the paper P from the fixing device 100 (nip portion) is changed. However, the present invention is not limited to this, and the paper P can be transported in the nip portion, for example. You may comprise so that the entry direction of may be changed. That is, the present invention can be applied even when the transport direction of the paper P shown in FIGS. 10A and 10B is reversed. In this case, since the part that affects the entry direction of the paper P is the upstream part of the nip portion in the transport direction, the upstream part of the transport direction is divided into the first position and the second position. What is necessary is just to comprise so that a curvature may change.

  In the above embodiment, the halogen lamp 120 and the nip plate 130 are integrally supported by the guide member 170. However, the present invention is not limited to this. For example, the halogen lamp is fixed to the main body housing, and the nip plate is used as the halogen lamp. It may be possible to move relative to the paper conveyance direction.

In the above-described embodiment, the reflecting plate 140 and the stay 160 are provided. However, the present invention is not limited to this, and the reflecting plate and the stay may be omitted.
In the embodiment, the halogen lamp 120 (halogen heater) is exemplified as the heating element. However, the present invention is not limited to this, and may be, for example, an infrared heater or a carbon heater.

In the embodiment, the plate-shaped nip plate 130 is exemplified as the nip member. However, the present invention is not limited to this, and a thick member that is not plate-shaped may be employed.
In the embodiment, the pressure roller 150 is exemplified as the backup member. However, the present invention is not limited to this, and may be, for example, a belt-like pressure member.

  In the above embodiment, the nip portion is formed by pressing the nip plate 130 against the pressure roller 150 (backup member). However, the present invention is not limited to this, and the backup member is pressed against the nip member. It is good also as a structure which forms a nip part. In this case, a mechanism for releasing the nip pressure by moving the backup member away from the nip member may be employed as the release mechanism.

  In the embodiment, the paper P such as plain paper or postcard is exemplified as the recording sheet, but the present invention is not limited to this, and may be, for example, an OHP sheet.

  In the above-described embodiment, the laser printer 1 is exemplified as the image forming apparatus including the fixing device of the present invention. However, the present invention is not limited to this. For example, an LED printer that performs exposure using LEDs may be used. It may be a copying machine or a multifunction machine. In the above-described embodiment, an image forming apparatus that forms a monochrome image is exemplified. However, the present invention is not limited to this, and an image forming apparatus that forms a color image may be used.

DESCRIPTION OF SYMBOLS 100 Fixing device 110 Fixing film 120 Halogen lamp 130 Nip plate 130A Plane part 130B Curved part 150 Pressure roller 190 Upper casing 191 Positioning recess 192 Operation piece 200 Lower casing 201 Positioning projection CM Release mechanism P Paper

Claims (4)

A cylindrical fixing film;
A heating element disposed inside the fixing film;
A nip member disposed so as to be in sliding contact with the inner surface of the fixing film and receiving radiant heat from the heating element;
A fixing device comprising a backup member that is elastically deformable and forms a nip portion with the fixing film by sandwiching the fixing film with the nip member in an elastically deformed state,
The nip member, by moving to the second position in the transport direction odor of the recording sheet Te first position and the first conveying direction upstream side of a position, the second and the first positions An adjustment mechanism that adjusts the conveyance direction of the recording sheet by making the backup member different in shape depending on the position ;
The nip member is disposed at the first position when the recording sheet thickness is less than or equal to a predetermined value, and the nip member is disposed at the second position when the recording sheet thickness is greater than the predetermined value. A control device for controlling the adjustment mechanism so as to
The amount of the nip member protruding from the backup member to the upstream side in the transport direction is larger when the nip member is located at the second position than when the nip member is located at the first position. A fixing device.   Of the surface on the backup member side of the nip member, the portion pressed by the backup member when the nip member is located at the first position is when the nip member is located at the second position. The fixing device according to claim 1, wherein the fixing device is formed with a curvature different from a curvature of a portion pressed by the backup member.   Of the surface on the backup member side of the nip member, the portion pressed by the backup member when the nip member is located at the first position is when the nip member is located at the second position. The fixing device according to claim 1, wherein the fixing device is a curved surface formed with the same curvature as a curvature of a portion pressed by the backup member. By moving one of the nip member and the backup member and away from the other, according to any one of claims 1 to 3, characterized in that it comprises a release mechanism for releasing the nip pressure Fixing device.

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