JP2020003697A - Fixing device and image forming apparatus - Google Patents

Abstract

To prevent an increase in the amount of curl of a sheet in association with a reduction in hardness of an elastic layer of a pressure roller without adding driving means and measuring means.SOLUTION: A fixing device 9 comprises: a pressure mechanism that presses a pressure roller 27 against a fixing roller 21 to form a pressure area N where a sheet S is sandwiched and conveyed between the pressure roller 27 and the fixing roller 21; a separation member 51 that is arranged on the downstream side of the pressure area N in a conveyance direction Y of the sheet S and is pressed against an outer periphery of the fixing roller 21 to separate the sheet from the fixing roller 21; and a movement mechanism 70 that moves the separation member 51 so that a contact position of the separation member 51 with the outer peripheral surface of the fixing roller 21 approaches the pressure area N, in conjunction with an approach of a core grid 271 to the fixing roller 21 in association with a reduction in hardness of an elastic layer 272 of the pressure roller 27.SELECTED DRAWING: Figure 4

Description

  The present invention relates to a fixing device that fixes a toner image on a sheet and an image forming apparatus including the fixing device.

  As a configuration of the fixing device for fixing the toner to the paper, a pressing roller including a cored bar and an elastic layer, a rotating member (a fixing roller, a fixing belt, etc.) contacting the outer peripheral surface of the pressing roller, and heating the rotating member And a pressure mechanism that forms a pressure area where a sheet is nipped and conveyed between the pressure roller and the rotation member by pressing the pressure roller against the rotation member. . A separating member that separates the sheet from the rotating member is disposed downstream of the pressing area in the sheet conveying direction.

  As a material of the elastic layer of the pressure roller, silicon rubber is usually used, but its hardness decreases with time. Particularly, in recent years, foamed silicone rubber having a low heat capacity has been used in many cases due to demand for energy saving, and foamed silicone rubber has a lower volume ratio of rubber to the whole volume as compared with solid rubber containing no pores. Hardness tends to decrease. When the hardness of the elastic layer decreases, the amount of deformation of the elastic layer increases, so that the pressurized area becomes longer in the paper transport direction. When the pressurized area becomes longer, the amount of heat transmitted to the sheet increases, so that the amount of water evaporating from the sheet increases, and the curl (curl) of the sheet increases. When the curl becomes strong, there is a high possibility that problems such as image rubbing and paper jam occur on the downstream side of the fixing device.

  Therefore, a technique for controlling the curl of the sheet by using a separating member has been studied. For example, Patent Literature 1 describes a configuration in which a peeling claw (separating member) is moved in a circumferential direction of a heating roller (rotating member) according to the thickness of a sheet. Japanese Patent Application Laid-Open No. H11-163,086 discloses that the inclination angle of a peeling plate (separating member) with respect to a plane perpendicular to a plane including a rotation axis of a fixing roller and a pressure roller in accordance with an axial distance between the fixing roller (rotating member) and the pressure roller. Is described. Patent Literature 3 describes a configuration in which the position where a peeling claw contacts a heat roller (rotating member) is changed according to the type of paper and the temperature and humidity. Patent Document 4 describes a configuration in which a contact position of a peeling claw with a heat roller is changed according to a curl amount of a sheet.

JP 2005308955 A JP-A-2002-287553 JP-A-4-365081 Japanese Utility Model Laid-Open No. 1-71780

  However, the configurations described in Patent Literatures 1 to 4 require a driving unit for adjusting the position, posture, and the like of the separation member. No consideration is given to a decrease in the hardness of the pressure roller. Further, the configurations described in Patent Documents 2, 3, and 4 require means for measuring the distance between axes, temperature and humidity, and curl amount, respectively. The addition of the driving means and the measuring means is not desirable from the viewpoint of energy saving because power consumption increases.

  In view of the above circumstances, the present invention provides a fixing device and an image forming apparatus capable of suppressing an increase in a curl amount of a sheet due to a decrease in hardness of an elastic layer of a pressure roller without adding a driving unit or a measuring unit. It is intended to provide a device.

  In order to solve the above problems, a fixing device according to the present invention includes a pressing roller including a cored bar and an elastic layer formed on an outer peripheral surface of the cored bar, and a rotating member that contacts an outer peripheral surface of the pressing roller. And a heating unit for heating the rotating member; and pressing the pressing roller against the rotating member to form a pressing area in which a sheet is nipped and conveyed between the pressing roller and the rotating member. A pressurizing mechanism, a separating member disposed downstream of the pressurizing area in the sheet conveying direction and abutting against an outer peripheral surface of the rotating member to separate the sheet from the rotating member; In conjunction with the approach of the core metal to the rotating member due to the decrease in hardness of the elastic layer of the roller, the separation is performed so that the contact position of the separating member with respect to the outer peripheral surface of the rotating member approaches the pressing area. Moved parts A moving mechanism that, characterized in that it comprises a.

  In the fixing device according to the aspect of the invention, the pressing mechanism may include a core supporting member that supports a core of the pressure roller, and a first urging member that urges the core supporting member toward the rotating member. Wherein the moving mechanism includes a guide member that guides the movement of the separation member in a direction that intersects the sheet conveyance direction, and a second urging member that urges the separation member toward the pressure roller. A wire connecting the core supporting member and the separating member, and a biasing direction of the second biasing member, which is disposed behind a connection position of the wire in the separating member, and the wire is wound around the wire. And a pulley that is provided.

  In the fixing device according to the present invention, the core support member may be a lever, and a connection position of the wire in a longitudinal direction may be variable.

  The fixing device according to the present invention further includes a separation member holder that rotatably supports the separation member, wherein the guide member guides the movement of the separation member via the separation member holder, The biasing member biases the separating member via the separating member holder, the wire is connected to the separating member via the separating member holder, and the separating member holder is attached to an outer peripheral surface of the rotating member. A third urging member for urging the separation member in the abutting direction may be provided.

  Further, an image forming apparatus according to the present invention includes an image forming unit that forms a toner image on the sheet, and any one of the fixing devices described above that fixes the toner image on the sheet.

  According to the present invention, it is possible to suppress an increase in the curl amount of a sheet due to a decrease in hardness of the elastic layer of the pressure roller without adding a driving unit, a measuring unit, and the like.

FIG. 1 is a front view schematically showing an internal configuration of a printer according to an embodiment of the present invention. FIG. 1 is a perspective view of a fixing device according to an embodiment of the present disclosure. FIG. 1 is a cross-sectional view of a fixing device according to an embodiment of the present disclosure. 1 is a front view of a fixing device according to an embodiment of the present disclosure. FIG. 3 is an exploded view of the separation member holder according to the embodiment of the present invention. It is a perspective view of the separation member concerning one embodiment of the present invention. It is a perspective view of a support member concerning one embodiment of the present invention. 1 is a front view of a fixing device according to an embodiment of the present disclosure. It is an experimental result of one embodiment of the present invention. FIG. 9 is a front view of a modification of the fixing device according to the embodiment of the present disclosure. FIG. 9 is a front view of a modification of the fixing device according to the embodiment of the present disclosure.

  Hereinafter, an image forming apparatus and a fixing device according to an embodiment of the present disclosure will be described with reference to the drawings.

  First, the overall configuration of a printer 1 as an image forming apparatus will be described with reference to FIG. FIG. 1 is a front view schematically showing the internal configuration of the printer 1. Hereinafter, the front side of the paper in FIG. 1 will be referred to as the front side (front side) of the printer 1, and the left and right directions will be described with reference to the direction when the printer 1 is viewed from the front. In each figure, U, Lo, L, R, Fr, and Rr indicate upper, lower, left, right, front, and rear, respectively.

  The apparatus main body 2 of the printer 1 includes a paper feed cassette 3 in which the paper S is stored, a paper feed device 5 that feeds the paper S from the paper feed cassette 3, an image forming unit 7 that forms a toner image on the paper S, The image forming apparatus includes a fixing device 9 for fixing the toner image to the sheet S, a sheet discharging device 11 for discharging the sheet S, and a sheet discharging tray 13 for receiving the discharged sheet S. In the apparatus main body 2, a transport path 15 of the sheet S from the paper feeding device 5 to the paper discharging device 11 via the image forming unit 7 and the fixing device 9 is formed.

  The sheet S fed from the sheet cassette 3 by the sheet feeding device 5 is transported to the image forming unit 7 along the transport path 15, and a toner image is formed on the sheet S. The sheet S is sent to the fixing device 9 along the transport path 15, and the toner image is fixed on the sheet S. The paper S on which the toner image has been fixed is discharged from the paper discharge device 11 to the paper discharge tray 13.

  Next, the configuration of the fixing device 9 will be described with reference to FIGS. FIG. 2 is a perspective view of a front portion of the fixing device 9. FIG. 3 is a sectional view of the fixing device 9. FIG. 4 is a front view of the fixing device 9. FIG. 5 is an exploded view of a front portion of the separation member holder 53. FIG. 6A is a perspective view of the separation member 51 to which the torsion coil spring 59 is attached. FIG. 6B is a perspective view of the support member 55 in which the separation member 51 is accommodated. Hereinafter, the front part of the fixing device 9 will be described, but the rear part has the same configuration as the front part except that the front and rear are reversed.

  As shown in FIGS. 2 and 4, the fixing device 9 includes a fixing roller 21 (an example of a rotating member), a halogen heater 23 (an example of a heating unit) that heats the fixing roller 21, a core metal 271 and an elastic layer 272. A pressure mechanism 27 for pressing the pressure roller 27 against the fixing roller 21, a separation member 51 for separating the sheet from the fixing roller 21, and a movement mechanism 70 for moving the separation member. Prepare. In the following description, the axial direction X refers to the axial direction (front-back direction) of the fixing roller 21 and the pressure roller 27. In the present embodiment, an example is shown in which the fixing device 9 is arranged in a position in which the pressure roller 27 is located below the fixing roller 21, but the fixing device 9 may be arranged in any position.

  As shown in FIG. 3, the fixing roller 21 has a cylindrical cored bar 211 and a release layer (not shown) formed on the outer peripheral surface of the cored bar 211. The core metal 211 is formed of a metal such as an Al alloy or stainless steel. The release layer is formed of PTFE, PFA, or the like. Although not shown, a cap and a rotating shaft are provided at an end in the longitudinal direction of the fixing roller 21, and the rotating shaft is supported by a bearing fixed to a housing of the fixing device 9.

  The halogen heater 23 is a rod-shaped halogen lamp whose longitudinal direction is the axial direction X, is disposed in the internal space of the fixing roller 21, and heats the fixing roller 21.

  The pressure roller 27 includes a core 271, an elastic layer 272 provided on the outer peripheral surface of the core 271, and a release layer (not shown) provided on the outer peripheral surface of the elastic layer 272. The core metal 271 is formed of a metal such as stainless steel or an Al alloy. The elastic layer 272 is formed of foamed silicon rubber or the like. The release layer is formed of PTFE, PFA, or the like. A driving force is transmitted to the pressure roller 27 from a driving source (not shown) such as a motor via a transmission mechanism (not shown) such as a gear. The core metal 271 is supported by the bearing 37.

  The pressure mechanism 30 presses the pressure roller 27 against the fixing roller 21 to form a pressure area N where the sheet S is nipped and conveyed between the pressure roller 27 and the fixing roller 21. Specifically, as shown in FIGS. 2 and 4, the pressing mechanism 30 includes a core supporting member 31 that supports the core 271 of the pressing roller 27, and the core supporting member 31 is moved to the fixing roller 21 side. A biasing compression coil spring 33 (an example of a first biasing member).

  The cored bar support member 31 is a member curved so that the left-right direction is the longitudinal direction and the central portion is located below the left end and the right end. The cored bar supporting member 31 is supported by a frame 35 fixed to a housing of the fixing device 9. A fulcrum 35F provided on the left side of the pressure roller 27 of the frame 35 supports the left end of the cored bar support member 31. The lower end of the compression coil spring 33 is connected to a pedestal 35B provided on the right side of the pressure roller 27 of the frame 35. The right end of the cored bar support member 31 is connected to the upper end of the compression coil spring 33. The bearing 37 of the pressure roller 27 is fitted in a concave portion 31U formed at a position closer to the left end than the center of the cored bar supporting member 31.

  The separating member 51 is disposed downstream of the pressing area N in the transport direction of the sheet S, and separates the sheet S from the fixing roller 21 by being abutted against the outer peripheral surface of the fixing roller 21. Specifically, as shown in FIGS. 3 to 5, the separating member 51 includes a rotating shaft portion 51A, a columnar portion 51P extending vertically from the rotating shaft portion 51A, and a longitudinal direction of the columnar portion 51P from the columnar portion 51P. And a wedge-shaped contact portion 51C formed so as to protrude in the intersecting direction.

  The separation member 51 is supported by the separation member holder 53. As shown in FIG. 5, the separation member holder 53 includes a support member 55 that supports the rotation shaft portion 51A of the separation member 51, and a stay 57 that supports the support member 55.

  The support member 55 has two housing portions 55S for housing the separation member 51. The housing portion 55S has a bottom plate portion 55F, and a wall portion 55W formed on the right side, the front side, and the rear side. A space surrounded by the bottom plate portion 55F and the wall portion 55W and having the longitudinal direction as a longitudinal direction is formed. Have been. Holes 55H into which both ends of the rotation shaft 51A of the separation member 51 are fitted are formed in the front and rear walls 55W. An opening 55o is formed in the center of the bottom plate 55F in the front-rear direction.

  As shown in FIG. 6A, a torsion coil spring 59 (an example of a third urging member) is fitted into the rotation shaft 51A of the separation member 51. As shown in FIG. 6B, both ends of the rotating shaft portion 51A are fitted into the holes 55H of the housing portion 55S with the front-rear direction being the axial direction of the rotating shaft portion 51A, and the columnar portion 51P is protruded from the opening 55o. 51 is accommodated in the accommodation section 55S. The first end portion 591 of the torsion coil spring 59 is formed in a hook shape, and is attached so as to wind around the columnar portion 51P of the separation member 51. The second end 592 of the separation member 51 is inserted into the notch 55K of the support member 55. The torsion coil spring 59 urges the separating member 51 so as to rotate the separating member 51 in a direction in which the contact portion 51C abuts on the outer peripheral surface of the fixing roller 21.

  The two storage portions 55S are provided side by side in the front and rear, and the support member 55 stores two separation members 51 in the front and rear. The separation member 51 on the rear side (the center side in the longitudinal direction of the fixing roller 21) of the two separation members 51 is disposed in a range in which a small-sized sheet passes (for example, a range of the long side of JIS B5 size), and the front side. The separation member 51 (at the end of the fixing roller 21 in the longitudinal direction) is disposed outside the passing range of the small-sized paper.

  As shown in FIGS. 2 and 5, the stay 57 is a plate-shaped member having the longitudinal direction in the front-rear direction and the same length as the fixing roller 21, and the support member 55 is fixed to the stay 57 with a screw 58. You. The front end of the stay 57 is bent at a right angle, and a protrusion 57P is formed so as to protrude forward from the front surface.

  As shown in FIGS. 2 and 4, the moving mechanism 70 includes a guide member 71 that guides the movement of the separation member 51 in a vertical direction (a direction that intersects the conveyance direction of the sheet S) and a pressing roller 27 that moves the separation member 51. A compression coil spring 73 (an example of a second biasing member) that biases to the side, a wire 75 that connects the cored bar support member 31 and the separation member 51, and a pulley 77 around which the wire 75 is wound are provided.

  The guide member 71 is a plate-shaped member fixed to the housing of the fixing device 9, and has a guide hole 71H whose longitudinal direction is the vertical direction. The protrusion 57P of the separation member holder 53 is inserted into the guide hole 71H of the guide member 71, and the separation member holder 53 is held by the guide member 71 so as to be movable in the vertical direction.

  The upper end of the compression coil spring 73 is connected to a pedestal 73B fixed to the housing of the fixing device 9, and the lower end of the compression coil spring 73 is connected to the upper surface of the stay 57 of the separation member holder 53. The separation member holder 53 is urged downward (toward the pressure roller 27) by the compression coil spring 73.

  A plurality of threaded holes 31H are formed at different positions in the longitudinal direction of the cored bar supporting member 31, and an eyebolt 79 is mounted in one of the plurality of holes 31H. The first end 751 of the wire 75 is connected to the eyebolt 79, and the second end 752 of the wire 75 is connected to the protrusion 57 </ b> P of the stay 57 of the separation member holder 53.

  The pulley 77 is provided on the guide member 71. In this example, two pulleys 77 are provided, but the number of pulleys 77 may be any number. However, at least the pulley 77 adjacent to the protrusion 57P of the stay 57 on the path of the wire 75 is disposed above the protrusion 57P. In other words, at least the pulley 77 adjacent to the protrusion 57P of the stay 57 on the path of the wire 75 is disposed behind the protrusion 57P in the biasing direction of the compression coil spring 73.

  Next, the fixing operation of the fixing device 9 will be described with reference to FIGS. The right end of the cored bar support member 31 is urged upward (toward the fixing roller 21) by the compression coil spring 33. Then, the core metal support member 31 rotates counterclockwise around the fulcrum 35F, and the pressure roller 27 is pressed against the fixing roller 21 by the action of the lever. In this way, a pressure area N where the paper S is nipped and conveyed is formed between the pressure roller 27 and the fixing roller 21.

  When the pressure roller 27 is driven and rotated, the fixing roller 21 is driven to rotate in a direction opposite to the rotation direction of the pressure roller 27. After the fixing roller 21 reaches a predetermined temperature by being heated by the halogen heater 23, the paper S to which the toner has been transferred is conveyed to the pressurizing area N. In the pressure area N, the sheet S is transported in the determined transport direction Y while being sandwiched between the fixing roller 21 and the pressure roller 27. At this time, the toner is heated and pressed by the fixing roller 21, and the toner is fixed on the sheet S. The sheet S on which the toner is fixed is conveyed downstream from the pressure area N in a state where the sheet S is stuck to the fixing roller 21, but is separated from the fixing roller 21 by the separating member 51 abutted against the fixing roller 21. Are transported along the transport path 15.

  As the above fixing operation is repeated, the hardness of the elastic layer 272 of the pressure roller 27 decreases. Then, since the core metal support member 31 is urged toward the fixing roller 21 by the compression coil spring 33, the amount of deformation of the elastic layer 272 increases, and the pressing area N in the transport direction Y of the sheet S becomes longer. When the pressurized area N becomes longer, the amount of heat transmitted to the sheet S increases, and the amount of moisture evaporated from the sheet S increases. Therefore, in the conventional fixing device, as the hardness of the elastic layer 272 of the pressure roller 27 decreases, the curl of the sheet S increases.

  Next, the operation of the present embodiment will be described with reference to FIGS. FIG. 7 is a front view illustrating a state of the fixing device 9 when the hardness of the elastic layer 272 is reduced. On the other hand, FIG. 4 shows a state before the hardness of the elastic layer 272 decreases. In this embodiment, as the amount of deformation of the elastic layer 272 increases due to a decrease in hardness, the eye bolt 79 approaches the fixing roller 21. Since the separation member 51 is urged toward the pressure roller 27 by the compression coil spring 73, the separation member 51 is pushed down as the eyebolts 79 approach the fixing roller 21. Since the separating member 51 is urged by the torsion coil spring 59 in a direction in which the contact portion 51 </ b> C abuts on the outer peripheral surface of the fixing roller 21, even if the position of the separating member 51 is lowered, the separating member 51 contacts the outer peripheral surface of the fixing roller 21. The state where the part 51C is abutted is maintained. Thus, the contact portion 51C approaches the pressure area N.

  According to the present embodiment, the contact position of the separation member 51 with the outer peripheral surface of the fixing roller 21 is increased in conjunction with the approach of the core metal 271 to the fixing roller 21 due to the decrease in the hardness of the elastic layer 272 of the pressing roller 27. Approaching the pressure region N. According to this configuration, the separation of the sheet S from the fixing roller 21 is accelerated as compared with a configuration in which the contact position of the separation member 51 with the outer peripheral surface of the fixing roller 21 does not change, so that the amount of heat transmitted to the sheet S increases. Is suppressed. Then, an increase in the amount of moisture evaporating from the sheet S is suppressed, and an increase in the curl amount of the sheet S is suppressed. Therefore, according to the present embodiment, it is possible to suppress an increase in the curl amount of the sheet S due to a decrease in the hardness of the elastic layer 272 of the pressure roller 27 without adding a driving unit, a measuring unit, and the like.

  Further, since the plurality of holes 31H have different distances from the fulcrum 35F, the amount of movement of the first end 751 with respect to the rotation angle of the cored bar support member 31 differs for each hole 31H. Therefore, by changing the position of the first end 751, the ratio of the amount of movement of the contact position of the separation member 51 to the amount of movement of the metal core 271 can be adjusted.

Next, experimental results of the embodiment will be described with reference to FIG. FIG. 8 is a list of experimental results. The fixing process is continuously performed on the paper having a basis weight of 52 g / m ² , and the deformation rate, the deformation amount, and the deformation amount of the elastic layer 272 in the initial state, after passing 150,000 sheets, and after passing 300,000 sheets. And the change in the position of the separation member were measured. Regarding the curl amount, the paper subjected to the fixing treatment was left on a flat surface, and the distance between the edge of the warped paper and the flat surface was measured. If the distance was 10 mm or less, it was evaluated as good (〇). The dimensions of the fixing roller 21 and the pressure roller 27 of the device used in the experiment are as follows.
-Outer diameter of fixing roller 21: 35 mm
-Thickness of the core metal 211 of the fixing roller 21: 0.7 mm
・ Outer diameter of pressure roller 27: 35mm
-Thickness of the elastic layer 272 (millable foam rubber) of the pressure roller 27: 9 mm

  The deformation ratio of the elastic layer was 20% in the initial state, increased to 25% after passing 150,000 sheets, and increased to 30% after passing 300,000 sheets. The amount of deformation of the elastic layer was 1.8 mm in the initial state, 2.25 mm (0.45 mm increase) after passing 150,000 sheets, and 2.7 mm (0 mm) after passing 300,000 sheets. 0.9 mm increase). The change in the position of the separation member was 0.4 mm after passing 150,000 sheets and 0.8 mm after passing 300,000 sheets. The curl amount evaluation was evaluated as good both after passing 150,000 sheets and after passing 300,000 sheets.

  The fixing device 9 may be modified as follows. FIG. 9 is a front view showing a modification of the fixing device 9. In this example, a pulley 77 is provided below the cored bar support member 31, and a tension coil spring 74 is provided instead of the compression coil spring 73 of the embodiment. The separating member 51 is urged upward by the tension coil spring 74. As the amount of deformation of the elastic layer 272 increases due to a decrease in hardness, the eye bolt 79 approaches the fixing roller 21, and the eye bolt 79 pulls the wire against the urging force of the extension coil spring 74, whereby the separation member 51 is pulled down. Since the separation member 51 is urged by the torsion coil spring 59 in a direction in which the contact portion 51C is brought into contact with the outer peripheral surface of the fixing roller 21, the contact portion 51C approaches the pressing area N.

  Further, the fixing device 9 may be modified as follows. FIG. 10 is a front view showing a modification of the fixing device 9. In this example, a moving mechanism 80 using a link mechanism instead of the moving mechanism 70 is provided. The moving mechanism 80 is configured such that one end of the link member 81 is pin-connected to the hole 31H of the cored bar support member 31, the other end of the link member 81 is pin-connected to one end of the link member 82, and the other end of the link member 82 is connected to the link member. The other end of the link member 83 is pin-coupled to the protrusion 57P of the stay 57. The center of the link member 82 is pin-connected to a suspension member 84 fixed to the housing. As the amount of deformation of the elastic layer 272 increases due to a decrease in hardness, the link member 81 moves upward, the link member 82 rotates clockwise, and the link member 83 moves downward. As a result, the separation member 51 is pushed down. Since the separation member 51 is urged by the torsion coil spring 59 in a direction in which the contact portion 51C is brought into contact with the outer peripheral surface of the fixing roller 21, the contact portion 51C approaches the pressing area N.

  In the above-described embodiment and modifications, the bearing 37 of the core 271 may be configured to be urged upward by a compression coil spring without the core support 31.

  Further, instead of the torsion coil spring 59, the separation member 51 may be configured to be urged by a tension coil spring, a compression coil spring, a plate spring, or the like.

  Further, a material having flexibility may be adopted for the contact portion 51C or the columnar portion 51P of the separation member 51, and the contact portion 51C or the columnar portion 51P may be configured to be pressed against the fixing roller 21 in a bent state. Good. In this case, the third biasing member is not essential.

  Further, the center of gravity of the separation member 51 may be located on the right side of the rotation center of the separation member 51 when the contact portion 51C is in contact with the fixing roller 21. In this case, the third biasing member is not essential.

  As a heating means in place of the halogen heater 23, a heat source such as a ceramic heater or an IH heater may be provided.

  A fixing belt is provided in place of the fixing roller 21, and a pressing member (a pressing pad or a sheet heater) that contacts the inner peripheral surface of the fixing belt is provided, and the pressing member and the pressing roller 27 sandwich the fixing belt 21. The present invention may be applied.

  Although the above description of the embodiment of the present invention describes a preferred embodiment of the fixing device and the image forming apparatus according to the present invention, various technically preferable limitations may be added in some cases. The technical scope of the present invention is not limited to these embodiments unless otherwise specified. That is, the components in the above-described embodiments of the present invention can be appropriately replaced with existing components and the like, and various variations including combinations with other existing components are possible, The above description of the embodiments of the present invention does not limit the contents of the invention described in the claims.

1 Printer (image forming device)
7 Image forming unit 9 Fixing device 21 Fixing roller (rotating member)
23 Halogen heater (heating means)
27 pressure roller 271 core metal 272 elastic layer 30 pressure mechanism 31 core metal support member 33 compression coil spring (first biasing member)
51 separation member 53 separation member holder 59 torsion coil spring (third biasing member)
70 moving mechanism 71 guide member 73 compression coil spring (second biasing member)
75 Wire 77 Pulley

Claims (5)

A pressure roller including a cored bar and an elastic layer formed on the outer peripheral surface of the cored bar,
A rotating member that contacts an outer peripheral surface of the pressure roller,
Heating means for heating the rotating member,
By pressing the pressing roller against the rotating member, a pressing mechanism that forms a pressing area in which a sheet is nipped and conveyed between the pressing roller and the rotating member,
A separating member that is disposed downstream of the pressurizing region in the sheet conveyance direction and that separates the sheet from the rotating member by being abutted against an outer peripheral surface of the rotating member;
In conjunction with the approach of the core metal to the rotating member due to the decrease in hardness of the elastic layer of the pressure roller, the contact position of the separation member with respect to the outer peripheral surface of the rotating member approaches the pressing region. And a moving mechanism for moving the separating member. The pressurizing mechanism,
A core supporting member for supporting the core of the pressure roller,
A first urging member that urges the core metal supporting member toward the rotating member;
The moving mechanism includes:
A guide member that guides the movement of the separation member in a direction that intersects the sheet conveyance direction,
A second urging member for urging the separation member toward the pressure roller;
A wire connecting the cored bar supporting member and the separating member,
2. The pulley according to claim 1, further comprising: a pulley that is disposed behind a connection position of the wire in the separation member in a biasing direction of the second biasing member and around which the wire is wound. 3. Fixing device.   The fixing device according to claim 2, wherein the core support member is a lever, and a connection position of the wire in a longitudinal direction is variable. A separation member holder that rotatably supports the separation member,
The guide member guides the movement of the separation member via the separation member holder,
The second biasing member biases the separation member via the separation member holder,
The wire is connected to the separation member via the separation member holder,
The fixing device according to claim 2, wherein the separation member holder includes a third urging member that urges the separation member in a direction in which the separation member holder abuts on an outer peripheral surface of the rotating member. An image forming unit that forms a toner image on the sheet,
An image forming apparatus comprising: the fixing device according to claim 1, wherein the fixing device fixes the toner image on the sheet.

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