JP2014174250A - Pressure device and image heating device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To achieve a configuration for easily performing the replacement operation of a fixing assembly 10 or the like.SOLUTION: An opening/closing cover 24 is supported to be rotatable between a shielding position for covering an opening and an opening position for opening the opening in a housing 25 having the opening through which the fixing assembly 10 can be taken in and out. A pressure arm 23 rotated together with the opening/closing cover 24 is energized by a pressure spring 15, to pressurize the fixing assembly 10. The pressure arm 23 is freely connected/disconnected to/from the pressure spring 15. The opening/closing cover 24 is fixed to the shielding position in such a state that the pressure arm 23 is connected to the pressure spring 15 and can be rotated to the opening position in such a state that the pressure arm 23 is disconnected from the pressure spring 15.

Description

  The present invention relates to a pressurizing device capable of inserting and removing a member to be pressurized to be pressed by a pressurizing member, and an image heating apparatus provided with such a pressurizing device.

  As an image forming apparatus such as a copying machine, a printer, a facsimile machine, and a multifunction machine of these, a configuration in which an image is formed using an appropriate image forming process such as an electrophotographic process or an electrostatic recording process is conventionally known. Then, the toner image formed by such an image forming process is transferred to a recording material such as a transfer sheet, an OHP sheet, printing paper, or format paper. The recording material onto which the toner image has been transferred is heated and pressed by a fixing device as an image heating device, whereby the toner image is fixed on the recording material.

  Such a fixing device includes a heating member for heating the recording material and a nip forming member for forming a nip portion for sandwiching the recording material between the heating member. Then, either one of the heating member and the nip forming member (pressurized member) is pressurized toward the other member so that the recording material passing through the nip portion is pressurized while being heated. ing. Further, as a combination of the heating member and the nip forming member, a combination of a pair of rollers and a combination of a belt such as a film and a roller are conventionally known.

  Such a heating member or a nip forming member (a member to be pressed) is detachably supported with respect to a housing in which these members are accommodated, and is taken in and out through an opening provided in the housing so as to be periodically replaced. . The opening is normally blocked by a cover for blocking the heat of the heating member and closing the opening, and the opening is exposed by removing the cover that covers the opening during regular replacement. The

  Here, a configuration in which a member to be pressed is pressed by an urging unit such as a spring in order to generate a pressing force in the nip portion has been conventionally known (see, for example, Patent Documents 1 and 2). In the case of the structures described in Patent Documents 1 and 2, the urging means are respectively provided at both ends of the member to be pressed, and are arranged on a trajectory in which the member to be pressed is taken in and out through the opening. In general, the cover that covers the opening is fastened to the housing separately from the urging means.

Japanese Patent No. 3282448 Japanese Patent No. 4672888

  However, in the case of the structure as described above, the replacement work of the member to be pressed becomes troublesome. That is, in order to take out the member to be pressed from the housing, it is necessary to remove the fastening member that fastens the cover in order to expose the opening, or to remove the urging means that is located on the locus for inserting and removing the member to be pressed. is there. For this purpose, for example, using a tool, the fastening member of the cover that covers the opening is removed, and the member that supports and fixes the biasing means is removed. Further, after the replacement member to be pressed is placed in the housing, a fastening member of a cover that covers the opening is attached and a member that supports and fixes the urging means is attached using a tool.

  As described above, when the member to be pressed is replaced, if the member for removing and attaching the cover fastening member and the member for supporting and fixing the urging means are removed and attached, it takes time to replace the member to be pressed. . As a result, the stop time (down time) of the image forming apparatus accompanying the replacement work is also lengthened, and convenience is lowered.

  In view of such circumstances, the present invention has been invented to realize a configuration capable of easily replacing the member to be pressed.

  The present invention accommodates a member to be pressed and has a housing having an opening through which the member to be pressed can be taken in and out, a shielding position that covers the opening, and an open position that opens the opening. A cover member that is rotatably supported with respect to the housing, and one end side of which is rotatably supported to rotate together with the cover member and pressurize the pressed member at the shielding position of the cover member A pressure member positioned at a pressure position where the pressure member can be applied, and the pressure member positioned between the other end of the pressure member positioned at the pressure position and the housing, and applying the pressure force to the pressure member. Urging means for urging in the direction, and the pressure member is freely connectable to and detachable from the urging means connected to the housing, and the cover member includes the pressure member. Fixed to the shielding position in a state connected to the biasing means, The hear member is pivotable to the open position in a state removed from the biasing means is a pressurized device, characterized in that.

  According to the present invention, the member to be pressed can be easily replaced by connecting or removing the pressing member to or from the urging unit.

1 is a schematic sectional view of an image forming apparatus according to an embodiment of the present invention. FIG. 3 is a cross-sectional view showing a part of the fixing device according to the present embodiment. FIG. 3 is an exploded perspective view showing a part of the fixing device according to the present embodiment. FIG. 3 is a perspective view illustrating a state where a cover of the fixing device according to the present embodiment is opened. FIG. 6 is a front view of the fixing device according to the present embodiment when being pressed by a pressure arm. The schematic diagram which shows the effect | action of force in the pressurization position of the pressurization arm in this embodiment. FIG. 3 is a front view of the fixing device showing a state in which the pressure applied by the pressure arm is released in the embodiment. The schematic diagram which shows the effect | action of the force in the state which cancelled | released the pressurizing force of the pressurization arm in this embodiment. The front view of the fixing device which shows the non-release state of the release arm in this embodiment. FIG. 3 is a front view of the fixing device showing an operation direction of a release arm in the present embodiment. FIG. 3 is a front view of the fixing device showing a release state of a release arm in the embodiment. FIG. 3 is a front view of the fixing device showing a state in which the pressure spring is removed from the release arm in the present embodiment.

  An embodiment of the present invention will be described with reference to FIGS. First, a schematic configuration of an image forming apparatus including a pressure device according to the present embodiment and a fixing device as an image heating device will be described with reference to FIG.

[Image forming apparatus]
As shown in FIG. 1, the image forming apparatus 100 includes a photosensitive drum (photosensitive member) 1 as an image carrier. The photosensitive drum 1 is configured by forming a photosensitive material such as OPC, amorphous Se, or amorphous Si on a cylindrical substrate such as aluminum or nickel.

  The photosensitive drum 1 is rotationally driven in the direction of the arrow shown in FIG. 1, and first, the surface thereof is uniformly charged by a charging roller 2 as a charging means. Next, scanning exposure with a laser beam α that is ON / OFF controlled according to image information is performed by a laser scanner 3 as an exposure unit, and an electrostatic latent image is formed. This electrostatic latent image is developed and visualized by the developing device 4. As a development method, a jumping development method, a two-component development method, a FEED development method (contact development method using a one-component insulating toner), or the like is used, and image exposure and reversal development are often used in combination.

  The visualized toner image is transferred from the photosensitive drum 1 onto the recording material P conveyed at a predetermined timing by a transfer roller 5 as a transfer unit. Here, the sensor 8 detects the leading edge of the recording material P so that the image forming position of the toner image on the photosensitive drum 1 matches the writing position of the leading edge of the recording material P, and the timing is adjusted.

  The recording material P conveyed at a predetermined timing is nipped and conveyed by the photosensitive drum 1 and the transfer roller 5 with a constant pressure. The recording material P to which the toner image has been transferred is conveyed to a fixing device 6 as an image heating device and fixed as an image.

  On the other hand, the residual toner remaining on the photosensitive drum 1 is removed from the surface of the photosensitive drum 1 by the cleaning device 7. The fixing device 6 is provided with a discharge sensor 9 that detects the leading edge of the recording material P. When the recording material P causes a paper jam (jam) between the sensor 8 and the discharge sensor 9, the fixing device 6 has a discharge sensor 9. Detect it.

[Fixing device]
Next, a schematic configuration of the fixing device 6 as an image heating device will be described with reference to FIGS. 2 and 3. The fixing device 6 includes a fixing assembly 10 as a heating member that heats an image carried on the recording material, and a counter roller 20 as a nip forming member that forms a nip portion N that holds the recording material between the fixing assembly 10. And a pressurizing device 200 which will be described in detail later. The fixing device 6 of this embodiment is a film heating system in which the fixing assembly 10 includes a fixing film 13.

  The fixing assembly 10 is a member to be pressed that is pressed by the pressing device 200, and includes a fixing film 13 as a flexible sleeve, a heater 11 as a heating unit, a heat insulating holder 12 that holds the heater 11, and The metal stay 14 is provided. Here, the metal stay 14 resists the heat-insulating holder 12 against the opposing roller 20 by receiving the pressure applied by the pressure spring 15 as an urging means via the pressure arm 23 and the flange 16 as pressure members. To press.

  The heater 11 is a ceramic heater formed in a plate shape and generates heat when energized. The heat insulating holder 12 holding the heater 11 is formed of a heat resistant resin such as liquid crystal polymer, phenol resin, PPS (polyphenylene sulfide), PEEK (polyether ether ketone). Since the lower the thermal conductivity, the better the heat conduction to the counter roller 20, a filler such as a glass balloon or a silica balloon may be included in the resin layer. It also has a role of guiding the rotation of the fixing film 13. The metal stay 14 comes into contact with the heat insulating holder 12 and suppresses bending and twisting of the entire fixing assembly.

[Fixing film]
The fixing film 13 is a heat-resistant film having a total thickness of 200 μm or less in order to enable a quick start of the image forming apparatus. As such a film, a heat resistant resin such as polyimide, polyamideimide, PEEK, or a pure metal such as SUS (stainless steel), Al, Ni, Cu, Zn, or an alloy having heat resistance and high thermal conductivity is used. It is formed as a base layer.

  In the case of a resin base layer, in order to improve thermal conductivity, high thermal conductive powder such as BN, alumina, Al, etc. may be mixed. Further, the fixing film 13 having a sufficient strength and excellent durability for constituting a long-life fixing device needs to have a total thickness of 20 μm or more. Therefore, the total thickness of the fixing film 13 is optimally 20 μm or more and 200 μm or less.

  Furthermore, in order to prevent offset and ensure separation of the recording material, the surface layer is mixed with a heat-resistant resin having a good releasability such as PTFE, PFA, FEP, ETFE, CTFE, PVDF, etc., and a silicone resin. And a release layer (release layer) is formed. In the present embodiment, the surface layer is made of a material containing at least PTFE and PFA. Here, PTFE is polytetrafluoroethylene, PFA is a tetrafluoroethylene / perfluoroalkyl vinyl ether copolymer, and FEP is a tetrafluoroethylene / hexafluoropropylene copolymer. ETFE is an ethylene tetrafluoroethylene copolymer, CTFE is polychlorotrifluoroethylene, and PVDF is polyvinylidene fluoride.

  As a coating method, the outer surface of the fixing film 13 may be etched and then the release layer may be dipped or applied by powder spraying or the like. Alternatively, a method of covering the surface of the fixing film 13 with a resin formed in a tube shape may be used. Alternatively, after the outer surface of the fixing film 13 is blasted, a primer layer that is an adhesive may be applied to cover the release layer.

[Opposite roller]
The opposing roller 20 is made of elastic material such as an elastic solid rubber layer, an elastic sponge rubber layer, or an elastic foam rubber layer on the outside of a metal core 21 made of SUS, SUM (sulfur and sulfur composite free-cutting steel), Al or the like. An elastic roller made of the layer 22. Here, the elastic solid rubber layer is formed of heat-resistant rubber such as silicone rubber or fluorine rubber. The elastic sponge rubber layer is formed by foaming silicone rubber in order to have a more heat insulating effect. The elastic foam rubber layer is a layer in which a hollow filler (such as a microballoon) is dispersed in a silicone rubber layer, and a gas portion is provided in the cured product to enhance the heat insulation effect. A release layer such as perfluoroalkoxy resin (PFA) or polytetrafluoroethylene resin (PTFE) may be formed thereon.

[Fixing device drive and control]
The fixing assembly 10 is pressed against the elasticity of the opposing roller 20 by a pressure device 200 described later, and forms a nip portion N. In the nip portion N, the fixing film 13 is bent by being sandwiched between the heater 11 and the counter roller 20 by the applied pressure, and is in close contact with the heating surface of the heater 11.

  The opposing roller 20 obtains a driving force that rotates in the direction of the arrow in FIG. 2 by a driving gear 17 provided at the end of the core bar 21 as shown in FIG. The driving force is transmitted from a motor 202 serving as a driving unit in accordance with a command from a control unit (CPU) 201 serving as a control unit. The control unit 201 is common to the control unit of the image forming apparatus 100, but may be included in the fixing device 6 itself.

  As the counter roller 20 is driven to rotate, the fixing film 13 is driven and rotated (moved) by the frictional force with the counter roller 20. At this time, the fixing film 13 slides with respect to the heater 11. Between the fixing film 13 and the heater 11, by interposing a lubricant such as fluorine-based or silicone-based heat resistant grease, the frictional resistance is kept low, and the fixing film 13 can be rotated smoothly (movable). It becomes.

  In addition, the temperature control of the heater 11 is performed by the control unit 201 determining the duty ratio, wave number, and the like of the voltage applied to the energization heating resistor layer of the heater 11 based on signals from temperature detection elements such as various thermistors. Do. The temperature in the nip portion N is maintained at a desired fixing set temperature. Here, various thermistors used for temperature control are a thermistor 18 provided on the back surface of the ceramic substrate and a thermistor 19 provided on the inner surface of the fixing film 13 for directly detecting the temperature of the fixing film.

  Further, the metal stay 14 is provided with a ground member 14 a for the purpose of grounding the fixing film 13. The ground member 14 a and the thermistor 19 are in sliding contact with the inner surface of the fixing film 13 in a state where the fixing film 13 is attached. For this purpose, the ground member 14a and the thermistor 19 include a member having a spring property such as a metal plate, and the tip protrudes with a spring property to the outside of the projected shape when the fixing film 13 is attached in a natural state. Is attached.

  As described above, the recording material P holding the unfixed toner image is nipped and conveyed by the nip portion N, and the toner image is heated and fixed on the recording material P. The recording material P discharged from the nip portion N is guided and discharged by a discharge guide (not shown).

[Pressure device]
Next, a pressure device 200 for pressing the fixing assembly 10 as a member to be pressed will be described with reference to FIGS. The pressure device 200 includes a housing 25, an opening / closing cover 24 as a cover member, a pressure arm 23 as a pressure member, and a pressure spring 15 as a biasing means. The housing 25 is also a housing of the fixing device 6 and has an opening 25a through which the fixing assembly 10, the opposing roller 20, and the like can be accommodated and the fixing assembly 10, the opposing roller 20, and the like can be inserted and removed. Such a housing 25 has a pair of support plates 25b. The fixing assembly 10 and the opposing roller 20 are accommodated between the support plates 25b and both ends thereof are supported.

  The opening / closing cover 24 is rotatable with respect to the housing 25 between a shielding position that covers the opening 25a of the housing 25 (position in FIG. 5) and an open position that opens the opening 25a (position in FIG. 4). Supported by Such an opening / closing cover 24 includes a cover portion 240 that covers the opening 25a, and a bent portion 241 that is formed so as to be bent from the base end side of the cover portion 240 to the housing 25 side. And the rotating shaft 241a provided in the edge part on the opposite side to the cover part 240 of the bending part 241 is each supported by the pair of support plates 25b of the housing 25 so that rotation is possible. Thereby, the opening / closing cover 24 is supported so as to be rotatable about the rotation center D (FIG. 5) with respect to the housing 25.

  The pressure arm 23 is rotatably supported at one end side and rotates together with the opening / closing cover 24, and a pressure position (position in FIG. 5) that can apply pressure to the fixing assembly 10 at the shielding position of the opening / closing cover 24. Located in. In the present embodiment, the pressurizing arm 23 is supported so that a base end portion on one end side thereof is rotatable with respect to the opening / closing cover 24. For this purpose, a cylindrical rotating part 23 b is formed at the base end of the pressure arm 23, and a rotation support part (boss) 24 c is formed at both ends of the base end side of the cover part 240 of the opening / closing cover 24. ing. Then, the pressurizing arm 23 rotates about the rotation center C (FIGS. 2 and 5) with respect to the opening / closing cover 24 by fitting the rotation portion 23b to the rotation support portion 24c. It is held freely.

  The open / close cover 24 includes a first restricting portion 24 a and a second restricting portion 24 b as detents for restricting relative rotation between the pressure arm 23 and the open / close cover 24. The first restricting portion 24a is formed at both ends of the cover portion 240 of the opening / closing cover 24 so as to cover the pressure arm 23 on the rotating side in the opening direction of the pressure arm 23 (direction of arrow B in FIG. 4). ing. When the pressure arm 23 rotates in the opening direction, a part of the pressure arm 23 and the first restricting portion 24a come into contact with each other, so that the pressure arm 23 is relative to the opening / closing cover 24 in the opening direction. Restricts rotation. That is, as the pressure arm 23 rotates in the opening direction, the opening / closing cover 24 rotates in the opening direction together with the pressure arm 23.

  On the other hand, the second restricting portion 24b is provided at the intermediate portion of the bent portion 241 of the opening / closing cover 24, on the rotation side in the shielding direction (the direction opposite to the arrow B in FIG. 4) of the pressing arm 23. It protrudes so as to cover the end. When the pressure arm 23 rotates in the shielding direction, a part of the pressure arm 23 and the second restricting portion 24b come into contact with each other, so that the pressure arm 23 is relative to the opening / closing cover 24 in the shielding direction. Restricts rotation. That is, as the pressure arm 23 rotates in the shielding direction, the opening / closing cover 24 rotates in the shielding direction together with the pressure arm 23.

  In the case of the present embodiment, a gap is provided between the first restricting portion 24a and the second restricting portion 24b and the pressure arm 23 so that the opening / closing cover 24 and the pressure arm 23 can be slightly rotated relative to each other. Such a rotation preventing portion that restricts the relative rotation is configured to support the pressure arm 23 so as not to rotate (or to allow slight rotation) with respect to the opening / closing cover 24, for example. It can also be configured.

  The pressure spring 15 is disposed between the distal end portion on the other end side of the pressure arm 23 located at the pressure position and the housing 25, and attaches the pressure arm 23 in the direction of applying pressure (pressure direction). Rush. In the present embodiment, the pressurizing spring 15 includes an engagement hole 25c serving as a housing-side connecting portion provided at one end of the housing 25 and a protrusion serving as a rotating-side connecting portion on the pressurizing arm 23 side. It is a tension spring connected to each of the parts (bosses) 29. In this embodiment, a coil spring is used. That is, the one end side hook portion 15 a formed at one end portion of the pressure spring 15 is hooked in the engagement hole 25 c of the housing 25, and the other end side hook portion formed in an annular shape at the other end portion of the pressure spring 15. 15b is hooked on the protrusion 29. And the pressurization arm 23 is urged | biased in the pressurization direction by arrange | positioning the pressurization spring 15 in the state elastically extended from the free state between the engagement hole 25c and the projection part 29. FIG. As will be described later, the protruding portion 29 constitutes a releasing mechanism 205 as a releasing means, and protrudes from a releasing arm 27 as a rotating portion connected to the tip of the pressure arm 23.

  Further, the pressurizing arm 23 can be connected to and detached from the other end of the pressurizing spring 15 whose one end is connected to the housing 25. That is, the pressure arm 23 can be detached from the other end portion of the pressure spring 15 by pulling the hook portion 15 b on the other end side of the pressure spring 15 from the protrusion 29 on the pressure arm 23 side. Further, the pressing arm 23 can be connected to the other end of the pressing spring 15 by inserting the protrusion 29 into the hooking portion 15 b on the other end side. Such connection and removal of the pressure spring 15 and the pressure arm 23 can be performed using a tool such as pliers even when the pressure spring 15 is pressurized. However, in the present embodiment, as will be described later, the pressure applied by the pressure spring 15 is released or reduced.

  The fixing assembly 10 is supported by flanges 16 serving as support portions at both ends. That is, by inserting an arcuate guide portion 16 a formed so as to protrude from the inner surface of the flange 16 into the end portion of the fixing film 13, both end portions of the fixing film 13 are guided by the guide portions 16 a of the flange 16 at both ends. Are supported rotatably. The flanges 16 at both ends are connected by a metal stay 14. Therefore, the flange 16 at both ends also supports the metal stay 14, the heat insulation holder 12 supported by the metal stay 14, the heater 11 held by the heat insulation holder 12, and the like. Further, the flanges 16 at both ends are respectively attached to the pair of support plates 25b of the housing 25 so as to be detachable and movable relative to the opposing roller 20. Further, on the outer surfaces of the flanges 16 at both ends, contact receiving portions 16b that contact the pressing arm 23 at the pressing position are projected.

  The pressure device 200 configured as described above applies pressure to the fixing assembly 10 via the flange 16 by the pressure arm 23 contacting the contact receiving portion 16b of the flange 16 at the pressure position. That is, the pressure spring 15 has one end connected to the housing 25 and the other end connected to the pressure arm 23. Further, the pressure arm 23 is held so as to be rotatable about the rotation center C, and one end of the pressure arm 23 is biased by the pressure spring 15 so that the pressure arm 23 is flanged at the pressure position. It abuts on 16 abutment receiving portions 16b. The pressure arm 23 applies a biasing force to the flange 16 and presses the flange 16 toward the opposing roller 20. The urging force transmitted to the flange 16 acts on both ends of the metal stay 14, and as a result, the metal stay 14 is pressed toward the facing roller 20. As a result, the heat insulating holder 12 disposed in contact with the metal stay 14 and the heater 11 disposed in contact with the heat insulating holder 12 are pressed together toward the opposing roller 20.

  Here, as shown in FIG. 3, the metal stay 14 has both ends in the longitudinal direction protruding from the heat insulating holder 12 and inserted into the flange 16, and the pressure arm 23 disposed on the flange 16 is pressurized. Pressurized by the spring 15. As a result, the load due to the pressure spring 15 is transmitted uniformly over the longitudinal direction of the heat insulating holder 12 through the stay foot 14b that contacts the heat insulating holder 12 of the metal stay 14. As described above, the metal stay 14, the heat insulating holder 12, and the heater 11 are pressed by the pressure spring 15, whereby the fixing film 13 is sandwiched between the heat insulating holder 12, the heater 11 and the counter roller 20. A nip portion N is formed.

[Attaching and removing the fixing assembly to the housing]
Next, a configuration for attaching and detaching the fixing assembly 10 to and from the housing 25 will be described with reference to FIGS. 4 and 5. The fixing assembly 10 is attached to the housing 25 so as to be detachable in an arrow A direction in FIG. 4 through an opening 25 a provided in the housing 25. An opening / closing cover 24 is rotatably attached to the housing 25. When the opening / closing cover 24 rotates in the direction of arrow B in FIG. 4, the opening 25a of the housing 25 is exposed, and the fixing assembly 10 is attached and detached. It becomes possible.

  Here, the pressure arm 23 for pressing the fixing assembly 10 toward the facing roller 20 is rotatably supported by a rotation support portion 24 c provided on the opening / closing cover 24. Then, by removing the pressure spring 15 connected to the other end of the pressure arm 23, the pressure arm 23 can be rotated integrally with the open / close cover 24 to the open position. In other words, the pressure arm 23 and the opening / closing cover 24 can be retracted from the removal direction locus of the fixing assembly 10 when the fixing assembly 10 is removed in the arrow A direction. That is, the pressure arm 23 is removed from the other end portion of the pressure spring 15 and rotated in the direction of arrow B in FIG. Then, the pressure arm 23 comes into contact with the first restricting portion 24a of the opening / closing cover 24, and the opening / closing cover 24 rotates in the direction of arrow B, that is, in the opening direction together with the pressure arm 23. As a result, the opening 25a is exposed and the fixing assembly 10 can be attached and detached.

  On the other hand, when the fixing device 6 is used, the opening 25 a is covered by rotating the opening / closing cover 24 in the direction opposite to the arrow B direction with the fixing assembly 10 mounted on the housing 25. At this time, the pressurizing arm 23 rotates together with the opening / closing cover 24 in the direction opposite to the arrow B direction by the second restricting portion 24b, and the opening / closing cover 24 becomes the shielding position. By connecting the pressure spring 15 to the tip of the pressure arm 23 at this position, as shown in FIG. 5, the force from the pressure spring 15 is applied to the pressure arm 15 with the pressure arm 23 as the pressure position. 23 is transmitted to the fixing assembly 10 via 23 and pressed toward the facing roller 20. Further, the open / close cover 24 is fixed to the shielding position in a state where the pressure arm 23 is connected to the pressure spring 15 in this way.

[Fixing the open / close cover]
Next, a mechanism for fixing the opening / closing cover 24 at the shielding position will be described with reference to FIGS. 5 and 6. FIG. 6 schematically shows the force acting on the pressure arm 23 and the opening / closing cover 24 at the pressure position of the pressure arm 23 of FIG. First, as shown in FIG. 6, the contact portion between the pressure arm 23 and the contact receiving portion 16 b of the flange 16 is set to point E in a state where the biasing force G <b> 1 by the pressure spring 15 is acting on the pressure arm 23. And Further, the force acting on the opening / closing cover 24 from the pressure arm 23 with the E point as a fulcrum by the urging force G1 is defined as G2. At this time, the force G2 causes the opening / closing cover 24 to have a rotation center D of the opening / closing cover 24 so that a moment H in the direction toward the shielding position is given to the opening / closing cover 24 around the rotation center D with respect to the housing 25. The position is set.

  Therefore, in the present embodiment, the position of the rotation center D of the opening / closing cover 24 is set so as to satisfy the following conditions. First, a point acting on the opening / closing cover 24 from the pressurizing arm 23 is defined as a point of action F with the point E as a fulcrum by the biasing force G1. In this case, the rotation center D of the opening / closing cover 24 is located in the direction of application of the urging force G1 with respect to the opening / closing cover 24 and is located on the fulcrum side (point E side) with respect to the action point F. In other words, the rotation center D is located on the shielding direction side (lower side in FIG. 6) with respect to the opening / closing cover 24 and is disposed between the action points F and E. This will be specifically described below.

  Normally, when the image forming apparatus is in operation, the fixing device 6 transmits a biasing force from the pressure spring 15 to the fixing assembly 10 to form the nip portion N, and the fixing assembly 10 and the opposing roller 20 are pressed against each other. At this time, the urging force of the pressure spring 15 acts on one end of the pressure arm 23 and gives a moment around the rotation center C to the pressure arm 23. The moment applied to the pressure arm 23 is transmitted as an urging force that presses the flange 16 in contact with the pressure arm 23 in the direction of the opposing roller 20 at the point E. As a result, the fixing assembly 10 moves in the direction of the opposing roller 20. It will be pressed.

  The pressure arm 23 is connected to the opening / closing cover 24 so as to be rotatable. For this reason, F is a contact portion between the opening / closing cover 24 and the pressure arm 23 when the point E as a contact point between the pressure arm 23 and the flange 16 is a fulcrum and the connection portion with the pressure spring 15 is a force point. On the other hand, an urging force corresponding to the point of action as defined by the lever principle is generated. The relationship between the forces acting on each part at this time is as shown in FIG.

  That is, the pressure arm 23 has one end connected to the pressure spring 15 and the other end connected to the open / close cover 24. When the pressing arm 23 is given a biasing force G1 by the pressing spring 15 in the direction of the arrow in FIG. 6, the pressing arm 23 is applied to the operating point F on the opening / closing cover 24 in the direction of the arrow with the point E as a fulcrum. Give power G2. Since the opening / closing cover 24 is supported by the housing 25 so as to be rotatable about the rotation center D, the urging force G2 applied to the opening / closing cover 24 is applied to the opening / closing cover 24 with a moment G3 and a vertical drag G4 indicated by arrows in the drawing. Replaced. Since the opening / closing cover 24 is configured to be rotatable about the rotation center D, a moment (rotational force) H in the direction of the arrow in the figure acts on the opening / closing cover 24 by the moment G3. By the action of this force, the opening / closing cover 24 is urged in a direction covering the opening 25 a of the housing 25 (direction toward the shielding position) only by connecting the pressure spring 15 to the pressure arm 23. As a result, the open / close cover 24 can be fixed at the shielding position without using a fastening means for fastening the open / close cover 24 to the housing 25 separately.

[Pressure adjustment mechanism]
Next, a pressure adjusting mechanism 203 as a pressure adjusting unit that adjusts the pressure applied to the fixing assembly 10 will be described with reference to FIGS. 7 and 8. The pressure adjusting mechanism 203 adjusts the pressure applied to the fixing assembly 10 by moving the pressure arm 23 positioned at the pressure position in the direction opposite to the direction in which the pressure is applied. For this purpose, the pressure adjusting mechanism 203 includes an adjustment cam 26 as a contact member that contacts the pressure arm 23 and moves the pressure arm 23, and a motor 204 as a drive unit that rotationally drives the adjustment cam 26. Have

  The adjustment cam 26 has outer peripheral surfaces with different distances from the center of rotation, and rotates to change the position of the outer peripheral surface in contact with the pressure arm 23 and move the pressure arm 23. Specifically, the adjustment cam 26 is rotatably supported by the housing 25 at a position on the urging direction side of the pressure spring 15 in the tip side portion in the vicinity of the tip side of the pressure arm 23. . The adjustment cam 26 is configured to have an outer shape that is a surface eccentric with respect to the rotation center. Then, the adjusting cam 26 is retracted to a position where it does not contact the pressurizing arm 23 at the pressurizing position, or contacts / presses the pressurizing arm 23 depending on the phase, and resists the urging force of the pressurizing spring 15. The pressure arm 23 is moved. Such rotation of the adjustment cam 26 is controlled by driving the motor 204 according to a command from the control unit 201, and the phase of the adjustment cam 26 can be set to an arbitrary position.

  As described above, the adjustment cam 26 comes into contact with the pressure arm 23 and pushes up the pressure arm 23 in the direction of the arrow in FIG. 7, whereby the pressure applied to the fixing assembly 10 is released or reduced by the pressure arm 23. That is, by setting the phase of the adjustment cam 26 to a position as shown in FIG. 7, the pressure arm 23 is separated from the contact receiving portion 16 b of the flange 16, and the pressure applied from the pressure arm 23 to the fixing assembly 10 is increased. To release. Even when the pressure arm 23 is in contact with the contact receiving portion 16b, the pressure applied by the pressure arm 23 is reduced by moving the pressure arm 23 from the pressure position shown in FIG. You may make it.

  This will be specifically described. For example, when the image forming apparatus is not in operation, the nip portion N is not formed or the microscopic pressure is usually small so that the elastic layer 22 of the opposing roller 20 does not cause distortion due to the pressing force from the fixing assembly 10. A clear nip is formed. Therefore, in the present embodiment, the adjustment cam 26 is brought into contact with and pressed against the pressure arm 23, and the adjustment cam 26 is adjusted to a predetermined phase so that the pressure arm 23 is displaced in the direction of the arrow in FIG. As a result, the fixing assembly 10 is pressed against the opposing roller 20 by the urging force from the pressure spring 15 or pressed with a light pressure. At this time, the urging force of the pressure spring 15 acts on one end of the pressure arm 23 and gives a moment around the rotation center C to the pressure arm 23. The moment applied to the pressure arm 23 is transmitted to the outer surface of the adjustment cam 26 that contacts the pressure arm 23 at point J, and the urging force transmitted to the fixing assembly 10 is cut off or reduced. As a result, the fixing assembly 10 is not pressed in the direction of the opposing roller 20 or is pressed with a minute pressure.

  On the other hand, during operation of the image forming apparatus, normally, the fixing device 6 forms a nip portion N, and the phase of the adjustment cam 26 is adjusted to a position where it is retracted from the pressure arm 23 in order to fix the toner on the recording material. (See FIG. 5). As a result, the urging force from the pressure spring 15 is transmitted to the fixing assembly 10, and the fixing assembly 10 and the opposing roller 20 are pressed to form a nip portion N, and heat is applied to the recording material passing through the nip portion N. And pressure can be applied.

  Further, when the type of the recording material that passes through the nip portion N changes, the width of the nip portion N (width in the recording material conveyance direction) may be changed. For example, in the case of thin paper, the width of the nip portion N is reduced to reduce the amount of heat applied. In the case of thick paper, the width of the nip portion N is increased to increase the amount of heat applied. There is. Even in such a case, the width of the nip portion N can be appropriately adjusted by changing the phase of the adjustment cam 26 and changing the pressure applied to the fixing assembly 10.

  Here, the mechanism in which the opening / closing cover 24 is fixed at the shielding position in a state where the pressure arm 23 is located at the pressure position has been described above. On the other hand, as described above, even when the applied pressure is released or reduced by the pressurizing adjustment mechanism 203 by the pressurizing arm 23, the open / close cover 24 needs to be fixed at the shielding position.

  Therefore, in the case of the present embodiment, the surface 23a of the pressure arm 23 that contacts the adjustment cam 26 is inclined so as to satisfy the following condition. As shown in FIGS. 7 and 8, the contact position between the adjustment cam 26 and the pressure arm 23 is point J, and the pressure arm 23 is opened and closed from the pressure arm 23 based on the biasing force G1 by the pressure spring 15. An action point at which a force acts on 24 is defined as an F point. A straight line passing through the point J and the point F is defined as a virtual line L. At this time, the virtual line L corresponds to a virtual arm in mechanics. Further, based on the biasing force G1, the reaction force received by the pressure arm 23 at point J is G5, and the reaction force received by the opening / closing cover 24 at the point of application F is G8. In this case, the above-described surface 23a has a rotation center D with respect to the housing 25 with respect to the opening / closing cover 24 by the resultant force of the reaction force G5 and the reaction force G8 based on the urging force G1 with respect to the virtual line L. The center is inclined so that a moment H in the direction toward the shielding position is applied.

  In the present embodiment, the pressure arm 23 has a pressure spring 15 as the surface 23 a in contact with the adjustment cam 26 moves toward the other end side of the pressure arm 23 (the tip side, the connection portion side with the pressure spring 15). It is formed so as to be inclined in the urging direction. As a result, the surface 23 a is provided with an angle that is not parallel to the imaginary line L, and the vertical force received from the adjustment cam 26 at point J generates a moment in the direction in which the opening / closing cover 24 is closed via the pressure arm 23. Hereinafter, this will be specifically described with reference to FIG. In the following description, when comparing the magnitudes of moments, the comparison is based on absolute values.

  When the pressing arm 23 is given a biasing force G1 in the direction of the arrow in the drawing by the pressing spring 15, the pressing arm 23 is given a moment with a point J as a contact position with the adjustment cam 26 as a fulcrum. At this time, the pressure arm 23 receives a vertical drag (reaction force) G5 from the adjustment cam 26 in the direction of the arrow in the figure at point J. Here, the normal force G5 has an angle that is not a right angle with respect to a virtual line L connecting the point of action F where the force acts on the open / close cover 24 from the pressure arm 23 with the point J as a fulcrum. For this reason, the normal force G5 can be replaced with a force G6 orthogonal to the virtual line L and a force G7 in the parallel direction with respect to the virtual line L. Of these two forces G6 and G7, the force G7 that is a component parallel to the imaginary line L is a force that pulls the pressure arm 23 along the imaginary line L in the G7 direction. Since the pressure arm 23 is connected to the opening / closing cover 24 at the point F, the drawing arm is pulled in the direction of the imaginary line L with a force G7, so that the arrow in the figure with respect to the opening / closing cover 24 about the rotation center D. Moment acts in the direction (same direction as moment H).

  On the other hand, when the pressing arm 23 is given a biasing force G1 by the pressing spring 15 in the direction of the arrow in the figure, the pressing arm 23 uses the point J as a fulcrum to the action point F on the opening / closing cover 24 in the direction of the arrow in the figure. An urging force G8 is applied. Since the opening / closing cover 24 is supported by the housing 25 so as to be rotatable about the rotation center D, the urging force G8 applied to the opening / closing cover 24 has a vertical drag G9 and a moment in the direction of the arrow in the figure. Replaced by G10. Since the opening / closing cover 24 is configured to be rotatable about the rotation center D, a moment in the direction opposite to the moment H direction in the direction of the arrow acts by the moment G10.

  Here, as described above, if the moment is greater than the moment G10 acting on the point F due to the force G7 acting on the point J, the moment H in the arrow direction in the figure acts on the opening / closing cover 24. In other words, due to the resultant force of the reaction force G5 at point J and the reaction force G8 at point F, a moment H is applied to the opening / closing cover 24 in the direction toward the shielding position with the rotation center D with respect to the housing 25 as the center. The Therefore, in the case of this embodiment, the moment acts on the F point by the force G7 acting on the J point by appropriately setting the position of the rotation center D and the inclination angle of the surface 23a of the pressure arm 23. It is set to be larger than the moment G10. As a result, a moment H acts on the opening / closing cover 24, and the opening / closing cover 24 is fixed at the shielding position.

  In the case of this embodiment, even when the pressure applied to the pressure arm 23 is released or reduced, the open / close cover 24 can be simply opened by connecting the pressure spring 15 to the pressure arm 23 and opening 25a of the housing 25. It is energized in the direction covering. Therefore, in the case of the present embodiment, the open / close cover 24 can be fixed at the shielding position regardless of the operation of the pressure adjusting mechanism 203 and without using a separate fastening means for fastening the open / close cover 24 to the housing 25 separately. .

  In the present embodiment, the moment G10 acting on the point F is opposite to the moment H direction that urges the opening / closing cover 24 to the shielding position. This is because the rotation center D of the opening / closing cover 24 with respect to the housing 25 is arranged as far as possible outside the fixing device 6. That is, various members such as the fixing assembly 10 are arranged inside the fixing device 6, and if the rotation center D is arranged on the center side of the fixing device 6, the degree of design freedom may be reduced. On the other hand, by disposing the rotation center D as far as possible outside the fixing device 6, the influence of the rotation portion of the opening / closing cover 24 on the arrangement of various members inside the fixing device 6 can be reduced, and the design is free. The degree is improved. On the other hand, when configured in this way, the moment G10 acting on the point F as described above acts in the direction opposite to the moment H direction. However, in the case of the present embodiment, by appropriately setting the inclination angle of the surface 23a of the pressure arm 23, the moment due to the force G7 acting on the point J is made larger than the moment G10. A force to fix the shield position is applied.

  Of course, the moment G10 acting on the point F may be set in the same direction as the moment H direction by moving the rotation center D of the opening / closing cover 24 relative to the casing 25 to the point J side of the position in FIG. In this case, since it is not necessary to make the moment due to the force G7 acting on the point J larger than the moment G10, the inclination angle of the surface 23a contacting the adjustment cam 26 of the pressure arm 23 with respect to the imaginary line L is larger than that in FIG. You can relax. For this reason, the freedom degree of design of the pressurization arm 23 improves. Further, if the moment due to the force G7 acting on the point J is smaller than the moment G10, the direction of the moment due to the force G7 may be opposite to the moment H direction.

[Release biasing force]
Next, a release mechanism 205 as release means for releasing the urging force by the pressure spring 15 will be described with reference to FIGS. 9 to 12. The release mechanism 205 is provided at a release arm 27 as a turning portion that is rotatably supported by the pressure arm 23, and at a position off the rotation center Q of the release arm 27, to which the pressure spring 15 is connected. And a projecting portion (boss) 29 as a rotating side connecting portion. Then, based on the rotation position of the release arm 27, the pressure arm 23 is pressurized by the urging force of the pressure spring 15, and the urging force of the pressure spring 15 applied to the pressure arm 23 is reduced or released. The position of the protrusion 29 is set so that the That is, as shown in FIG. 9, when the release arm 27 is positioned at a predetermined position, the pressure arm 23 is pressurized by the urging force of the pressure spring 15 via the release arm 27. On the other hand, as shown in FIG. 11 or FIG. 12, when the release arm 27 is located at the release position rotated by a predetermined angle from the predetermined position, the urging force of the pressure spring 15 is reduced or less than when it is located at the predetermined position. Canceled. This will be specifically described below.

  The base end of the release arm 27 is connected to the other end of the pressure arm 23 so as to be rotatable with respect to the pressure arm 23 about the rotation shaft 28. A protruding portion 29 for connecting the pressure spring 15 is provided at the base end portion of the release arm 27, and the other end side hook portion 15 b formed on the other end portion of the pressure spring 15 is hooked on the protruding portion 29. Thus, the pressure spring 15 and the release arm 27 are connected. Further, the pressure spring 15 and the housing 25 are connected by the connecting portion K by hooking the one end side hooking portion 15 a formed at one end of the pressure spring 15 in the engagement hole 25 c provided in the housing 25. . As a result, the urging force of the pressure spring 15 is applied to the pressure arm 23 via the release arm 27.

  Further, the protruding portion 29 of the release arm 27 is provided at a position deviated from the rotation center Q of the rotation shaft 28, and the protrusion portion is formed by rotating the release arm 27 about the rotation shaft 28. The distance between 29 and the connecting portion K changes. That is, by rotating the release arm 27 in the direction of arrow M1 (release direction) in FIG. 9, the protrusion 29 is rotationally displaced about the rotation shaft 28. A handle portion 27a for operating the release arm 27 during the release operation is provided on the distal end side of the release arm 27.

  Then, the distance between the protrusion 29 and the connecting portion K is reduced by the rotation of the release arm 27, and the protrusion is at the release position where this distance is equal to or less than the natural length of the pressure spring 15. The hook portion 15b on the other end side of the pressure spring 15 can be detached from the portion 29. In other words, in the case of this embodiment, the position of the projection 29 is the release position of the release arm 27, and the distance between the projection 29 and the connection portion K (engagement hole 25 c) is less than the natural length of the pressure spring 15. It is set to become.

  By removing the pressure spring 15 connected to the protrusion 29 at such a release position, the open / close cover 24, the pressure arm 23, and the release arm 27 can rotate integrally around the rotation center D. It becomes. As described above, the fixing assembly 10 can be attached.

  On the other hand, by rotating the release arm 27 in the arrow M2 direction (non-release direction) in FIG. 10, the distance between the protrusion 29 and the connection portion K is made longer than the natural length of the pressure spring 15, The urging force of the pressure spring 15 is applied. At this time, as shown by a broken line in FIG. 9, the release arm 27 is restricted from rotating by the contact portion 27 b at the tip contacting the bottom plate portion 23 c of the pressure arm 23. That is, when the contact portion 27b contacts the bottom plate portion 23c, the release arm 27 is restricted from further rotating in the arrow M2 direction with respect to the pressure arm 23. In addition, in this state, the urging force of the pressure spring 15 acts on the protrusion 29, whereby a moment in the direction of the arrow M2 is applied to the release arm 27, and the contact portion 27b reliably contacts the bottom plate portion 23c. As a result, the release arm 27 is fixed to the pressure arm 23.

  Next, the force acting on each part by the operation of the release arm 27 will be described in more detail. In the present embodiment, the connecting portion K, the protruding portion 29, and the rotating shaft 28 are set so as to satisfy the following conditions. First, as described above, the release arm 27 is attached to the pressure arm 23 so as to be rotatable about the rotation shaft 28, and can be rotationally displaced along the locus shown in FIGS. FIG. 9 shows a state where the release arm 27 is in a non-released state (pressure spring 15 set state). In this state, an imaginary line (straight line) L1 connecting the center of the protrusion 29 connected to the pressure spring 15 provided on the release arm 27 and the connection portion K between the housing 25 of the pressure spring 15 is a release arm 27. It is located in the non-releasing direction with respect to the rotation shaft 28 of the. Then, the urging force of the pressure spring 15 applies a moment that urges the release arm 27 to the non-release position (pressure spring 15 set position, predetermined position).

  Here, the distance L2 between the center (rotation center Q) of the rotation shaft 28 of the release arm 27 and the center of the projection 29 and the distance L3 between the center of the rotation shaft 28 and the handle portion 27a are sufficient. The lever ratio, for example, L3 is set to be 5 times L2. As a result, even if the release arm 27 is urged to the non-release position by the urging force of the pressure spring 15 (for example, 300 N), only the force obtained by multiplying the reciprocal of the lever ratio (for example, 5) using the lever principle. The release arm 27 can be rotated in the release direction against the urging force.

  When the release arm 27 is rotated in the release direction to the position of FIG. 10, the imaginary line L1 connecting the center of the protrusion 29 and the connection portion K passes over the center of the rotation shaft 28 of the release arm 27 and is in this state. In, the moment urged to the non-release position of the release arm 27 disappears. When this position is taken as a branch and the release arm 27 is rotated toward the non-release position, the release arm 27 is given a moment biased to the non-release position by the pressure spring 15. On the other hand, when the release arm 27 is rotated in the release direction from the above-described position, the release arm 27 is given a moment to be biased to the release position by the pressure spring 15.

  When the release arm 27 is further rotated in the release direction to the position shown in FIG. 11, the distance between the protrusion 29 and the connection portion K becomes equal to the natural length of the pressure spring 15. Disappears. For this reason, the pressure spring 15 can be easily detached from the protrusion 29.

  Further, when the release arm 27 is rotated to the position of FIG. 12, the distance between the projection 29 and the connection portion K is minimized, and the distance L4 at that time is shorter than the natural length L5 of the pressure spring 15. Is set. As a result, even if the distance L4 between the protrusion 29 and the connecting portion K varies due to the variation in the shape of the parts and the mounting accuracy, the distance L4 can be surely shorter than the natural length L5 of the pressure spring 15. . Then, the pressure spring 15 is set so as to ensure that the pressure spring 15 can be removed and loaded without load because the pressure spring 15 always has a no-load state.

  In the case of the present embodiment, the position shown in FIG. 11 may be set as the release position, but it is preferable to set the position shown in FIG. That is, it is preferable that an angle obtained by rotating the release arm 27 from the non-release position (predetermined position) in FIG. 9 to the position in FIG.

  When removing the pressure spring 15 from the protrusion 29, it is preferable that the urging force of the pressure spring 15 disappears. However, if the urging force of the pressure spring 15 is reduced as compared with the case where the release arm 27 is positioned at a predetermined position, the pressure spring 15 can be removed somewhat easily. It can also be set to a position where the biasing force of the spring 15 is not lost.

  In the above description, the pressure arm 23 and the opening / closing cover 24 can be rotated by removing the hook portion 15 b on the other end side of the pressure spring 15 from the protrusion 29. However, for example, by enabling the release arm 27 to be separated from the pressure arm 23 at the release position, the release arm 27 and the pressure spring 15 are detached from the pressure arm 23, and the pressure arm 23 and the opening / closing cover 24 are removed. It is good also as possible to turn. In this case, the pressure spring 15 can be detached from the pressure arm 23 while the pressure spring 15 is attached to the release arm 27.

  Further, the pressure spring 15 may be removed from the housing 25. That is, the hooking portion on one end side of the pressure spring 15 may be removed from the housing 25 while the pressure spring 15 and the pressure arm 23 are connected. Even in such a configuration, since the urging force of the pressure spring 15 is reduced or released, the pressure spring 15 can be easily removed.

  According to the present embodiment configured as described above, the fixing arm 10 can be easily replaced by connecting the pressure arm 23 to the pressure spring 15 or removing it from the pressure spring 15. That is, the open / close cover 24 is fixed to the shielding position with the pressure arm 23 connected to the pressure spring 15, and can be rotated to the open position with the pressure arm 23 removed from the pressure spring 15. For this reason, when taking out the fixing assembly 10 from the housing 25, the opening / closing cover 24 can be rotated to the open position by removing the pressure arm 23 from the pressure spring 15. At this time, since the pressure arm 23 also rotates together with the opening / closing cover 24, the pressure arm 23 and the opening / closing cover 24 are retracted from the removal direction locus of the fixing assembly 10 by operating any one of them. Can be easily taken out from the housing 25.

  In short, in the case of the present embodiment, when the fixing assembly 10 and the counter roller 20 are exchanged, the moment for urging and fixing the open / close cover 24 is obtained simply by releasing the connection of the pressure spring 15 from the pressure arm 23. It will be resolved. For this reason, simply by rotating and releasing the opening / closing cover 24, the pressure arm 23 rotatably connected to the opening / closing cover 24 is retracted from the locus of the fixing assembly 10 in a substantially integrated manner with the opening / closing cover 24. Then, the opening 25 a of the housing 25 is exposed, and the fixing assembly 10 can be attached to and detached from the fixing device 6 without removing the parts from the fixing device 6.

  On the other hand, after the fixing assembly 10 is put in the housing 25, the opening / closing cover 24 is rotated together with the pressure arm 23 to be in the shielding position, and the opening / closing cover 24 is fixed by connecting the pressure arm 23 to the pressure spring 15. Is done. For this reason, the opening / closing cover 24 can be fixed at the shielding position without using a fastening means for fastening the opening / closing cover 24 to the housing 25 separately. As a result, the fixing assembly 10 can be easily attached to the housing 25. The replacement operation of the facing roller 20 can be easily performed together with the fixing assembly 10.

  In the case of the present embodiment, since the pressure adjusting mechanism 203 that adjusts the pressure force by moving the pressure arm 23 is provided, the pressure force applied to the opposing roller 20 of the fixing assembly 10 even in the above-described configuration. Can be adjusted. As a result, it is possible to suppress the elastic layer 22 of the facing roller 20 from being distorted by the pressing force from the fixing assembly 10 when the fixing device is not in operation. In addition, the width of the nip portion N can be adjusted appropriately according to conditions such as the type of recording material.

  Further, in the case of the present embodiment, since the urging force of the pressure spring 15 can be reduced or released by rotating the release arm 27, the release arm 27 is operated to pressurize the pressure arm 23 of the pressure spring 15. Can be easily removed from. As a result, when the fixing assembly 10 and the counter roller 20 are exchanged, the pressure spring 15 can be simply attached to the pressure arm 15 without using a tool or the like to disconnect the pressure spring 15 from the pressure arm 23. It becomes possible to release the connection from 23.

  As described above, in this embodiment, when the fixing assembly 10 and the like are replaced, the opening / closing operation of the opening / closing cover 24 can be easily performed. In particular, it is not necessary to attach or remove parts such as fastening means for fixing the opening / closing cover 24. Further, it is not necessary to use a tool for attaching and removing the pressure spring 15. As a result, the time required for the replacement work can be shortened, so that the downtime of the image forming apparatus can be shortened and the convenience is improved. In addition, since the replacement work becomes easy, the parts can be attached more accurately.

<Other embodiments>
In the above-described embodiment, the configuration of the combination of the fixing assembly having the fixing film and the counter roller has been described as the fixing device, but the present invention is not limited to this configuration. For example, the present invention can be applied to a configuration in which a fixing roller having a heater therein, a heating belt heated by electromagnetic induction heating, or the like is used as a heating member constituting the fixing device.

  In addition, the member to be pressed in and out of the housing may be a nip forming member such as a counter roller instead of a heating member such as a fixing assembly. In other words, the pressurizing device of the present invention may be any device that pressurizes either one of the heating member and the nip forming member toward the other member.

  Further, the urging means for urging the pressing member may have a configuration other than the tension spring as described above. For example, it may be a compression spring that urges the pressing member with an elastic restoring force in a direction extending from an elastically compressed state.

  Further, the pressure adjusting means for adjusting the pressure applied to the member to be pressed can be configured other than the configuration using the cam as described above as long as the pressing member is moved. For example, using a rack and pinion, the rotational force of the motor may be converted into a linear force, and the pressure member may be moved by the linear force.

  6... Fixing device (image heating device), 10... Fixing assembly (pressurized member, heating member), 15... Pressurizing spring (biasing means, tension spring), 15a. Hooking part, 15b ... Hooking part (hooking part) on the other end side, 16 ... Flange (supporting part), 20 ... Opposing roller (nip forming member), 23 ... Pressure arm (pressure member) ), 24... Open / close cover (cover member), 24 a... First restricting portion (rotation stop), 24 b... Second restricting portion (rotation stop), 25. , 25c... Engagement hole (frame side connection part), 26... Adjustment cam (contact member), 27... Release arm (rotation part), 28. ..Protrusions (rotation side connecting portions), 200... Pressurizing device, 203... Pressurizing adjusting mechanism (pressurizing adjusting means), 2 5 ... release mechanism (release means)

Claims (6)

A housing having an opening that is capable of accommodating the member to be pressed and into which the member to be pressed can be taken in and out,
A cover member that is rotatably supported with respect to the housing between a shielding position that covers the opening and an open position that opens the opening;
One end side is rotatably supported and rotates together with the cover member, and a pressurizing member located at a pressurizing position capable of applying pressure to the pressed member at the shielding position of the cover member;
An urging means disposed between the other end side of the pressure member located at the pressure position and the casing, and urging means for urging the pressure member in a direction in which the pressure is applied;
The pressure member is freely connectable and detachable with respect to the urging means connected to the housing,
The cover member is fixed to the shielding position in a state where the pressure member is connected to the biasing means, and is rotatable to the open position in a state where the pressure member is removed from the biasing means.
A pressure device characterized by that. The pressure member is supported at one end side with respect to the cover member,
A detent that restricts relative rotation between the pressure member and the cover member;
The pressurizing device according to claim 1, wherein: A support portion for supporting the member to be pressed;
The pressurizing member applies pressure to the pressed member through the support portion by contacting the support portion at the pressurizing position.
The pressurizing device according to claim 1 or 2, wherein With the urging force of the urging means acting on the pressure member, the force acting on the cover member from the pressure member with the contact portion between the pressure member and the support as a fulcrum The position of the rotation center of the cover member is set so that a moment in the direction toward the shielding position is given to the cover member with the rotation center relative to the housing as a center.
The pressurizing device according to claim 3, wherein In a state where the urging force by the urging means is acting on the pressure member, a point acting on the cover member from the pressure member with a contact portion between the pressure member and the support portion as a fulcrum. In the case of an action point, the rotation center of the cover member is located in the action direction of the urging force with respect to the cover member, and is located on the fulcrum side with respect to the action point.
The pressurizing apparatus according to claim 3 or 4, characterized in that. A heating member for heating the image carried on the recording material;
A nip forming member for forming a nip portion for sandwiching the recording material with the heating member;
In an image heating apparatus comprising: a pressurizing device that pressurizes either one of the heating member and the nip forming member toward the other member;
The pressurizing device is the pressurizing device according to any one of claims 1 to 5,
Either one of the heating member and the nip forming member is the pressed member.
An image heating apparatus.

Images