JP4677312B2 - Image forming apparatus - Google Patents

Description

  The present invention relates to an image forming apparatus having a function of forming an image on a recording medium such as a sheet, such as a copying machine, a printer, or a facsimile machine.

  In an image forming apparatus such as a laser printer using an electrophotographic system, a unit (for example, a fixing unit) having lower durability than the image forming apparatus main body is prepared as an exchange unit. Then, after a predetermined number of prints and copies, replacement by a service person is performed. However, in such a case, there are concerns that labor costs will be incurred and replacement costs will be expensive.

  In view of this, an image forming apparatus employing a method in which a user replaces such a replacement unit has been proposed (see Patent Document 1).

  For such image forming devices, unlike service technicians, operators who are not trained in the structure and handling of the image forming device perform replacement work, so be careful not to attach or remove units or forget to install components. There is a need to.

On the other hand, there has also been proposed an image forming apparatus that improves the usability of jam processing by releasing the clamping pressure of the fixing means in conjunction with an opening / closing door (opening / closing member) during jam processing of the fixing device (see Patent Document 2). .
Japanese Patent Laid-Open No. 11-184332 JP 2002-148992 A

  However, in an image forming apparatus in which the fixing unit can be replaced and linked to the open / close door during jam processing to release the clamping pressure of the fixing unit, after the fixing unit is replaced, the fixing is performed in conjunction with the open / close door during jam processing. There is a concern that the clamping pressure of the means cannot be released. This is because it is difficult to release the connection between the fixing pressure releasing means and the open / close door of the fixing means, or there is a concern that the connection may be forgotten after replacement of the fixing unit.

  The present invention has been made in view of the circumstances as described above. The fixing device can be easily replaced, and the connection between the opening / closing member and the means for releasing the clamping pressure of the fixing device is realized with a simple configuration. An object is to provide a good image forming apparatus.

In order to achieve the above object, the present invention provides:
An image forming unit for transferring a toner image obtained by developing the electrostatic latent image formed on the image carrier to a sheet;
Fixing means for fixing the toner image formed on the sheet in a state where the sheet is held at a predetermined pressure at the nip portion;
An opening and closing member provided to be openable and closable with respect to the apparatus body, and exposing the inside of the apparatus body when opened;
In an image forming apparatus comprising:
Fixing pressure release having a release means provided on the downstream side of the fixing means in the sheet conveying direction so as to be detachable from the apparatus main body and releasing the clamping pressure of the fixing means on the sheet in conjunction with the opening operation of the opening / closing member. Means,
Fixing means for fixing the fixing pressure releasing means to the apparatus body;
With
The fixing means is fixed to the apparatus main body by the fixing means in a state where the fixing means is sandwiched between a support portion provided in the apparatus main body and the fixing pressure releasing means. Is supported and fixed to the apparatus main body.

  According to the present invention, it is possible to provide an image forming apparatus with good usability in which the fixing device can be easily replaced, and the connection between the opening / closing member and the means for releasing the clamping pressure of the fixing device is realized with a simple configuration. Become.

  The best mode for carrying out the present invention will be exemplarily described in detail below with reference to the drawings. However, the dimensions, materials, shapes, and relative arrangements of the components described in this embodiment should be appropriately changed according to the configuration of the apparatus to which the invention is applied and various conditions. It is not intended to limit the scope to the following embodiments.

  An image forming apparatus according to an embodiment of the present invention relates to an image forming apparatus including a mechanism that interlocks release of a clamping pressure for a sheet in an exchangeable fixing device with opening and closing of an opening / closing member.

{overall structure}
First, the overall configuration of the image forming apparatus 1 according to the first embodiment of the invention will be described. FIG. 2 is a schematic cross-sectional view illustrating the overall configuration of the image forming apparatus 1. An image forming apparatus 1 illustrated in FIG. 2 is a printer including an image reading unit as an example of an image forming apparatus. In this embodiment, the operation panel of the image forming apparatus is provided on the front surface of the image forming apparatus, which is the front side of the paper surface shown in FIG. For this reason, the user stands on the front surface of the image forming apparatus so that the image forming apparatus looks like FIG. Therefore, in the following description, for convenience of explanation, the front side direction of the image forming apparatus is referred to as “front (side)”, and the rear side (back side of the paper surface shown in FIG. 2) is set to “back (side)” and rear side. " The orientation of the apparatus to which the image forming apparatus is applied is not limited to this.

In FIG. 2, feeding cassettes 2 and 3, feeding rollers 4 and 5, and separation pads 6 and 7 constituting a sheet feeding unit are arranged at the lower part of the image forming apparatus 1.
The sheets fed from the feeding cassettes 2 and 3 by the feeding rollers 4 and 5 are separated and conveyed one by one by the separation pads 6 and 7. The sheet fed from the feeding cassettes 2 and 3 is conveyed to the image forming unit by the sheet conveying path 8 and the registration rollers 9.

  The image forming unit includes an image forming process unit (hereinafter referred to as “cartridge”) 11 having an image forming drum 10 as an image carrier, and in this embodiment, image exposure is performed from the scanner 14 to the image forming drum 10. A toner image is formed by a known electrophotographic method, and this is transferred and formed on a conveyed sheet.

  The sheet on which the image has been formed is heated and pressed in a fixing device 100 as a fixing unit, and the toner image is fixed. The sheet on which the toner image is fixed is discharged to a discharge tray 30 serving as a discharge portion by a fixing discharge roller 112 and a fixing discharge roller 113 that constitute discharge means, and a discharge roller pair 20.

  A duplex unit 300 for duplex printing is configured to be insertable from the left side of the image forming apparatus 1 shown in FIG. In the image forming apparatus 1, a duplex conveyance path capable of duplex printing is formed with the duplex unit 300 attached. A controller necessary for double-sided printing, a fan for cooling the image forming apparatus, a driving unit (not shown) for driving the roller, and the like are accommodated in the projecting portion 300a from the exterior surface of the left door 60 as an opening / closing member. Has been.

  The sheet S on which an image is formed on one side is reversed at a position conveyed from the fixing discharge roller 112 and the fixing discharge roller 113 at a predetermined position, and is conveyed to the duplex conveyance path. Then, an image is also formed on the opposite surface, and is discharged onto the discharge tray 30 by the discharge roller pair 20 in the same manner as the image formation on only the first surface.

  An image reading unit is disposed above the image forming apparatus 1. As shown in FIG. 2, the image reading unit includes a scanner unit 51 and an ADF 52 which are image reading units. The ADF 52 separates and conveys a plurality of documents stacked on the document stacking tray 53 one by one by a feed roller 54 and a separation pad (not shown), and optically reads document description information by passing through a document reading position 56. Is. The ADF 52 can be opened and closed rearward around a hinge (not shown) at the rear of the apparatus, and is opened and closed when a document is placed on the document table glass 57.

  The scanner unit 51 is a general unit that reads the document description information while the optical carriage 58 scans the document placed on the document table glass 57 along a guide shaft (not shown) in the lateral direction, and performs photoelectric conversion by the CCD. . When the original is read by the ADF 52, the optical carriage 58 stops at a predetermined position and reads the original being conveyed. A detailed description of the scanner unit is omitted here.

{Description of configuration of fixing unit and jam processing unit}
Next, the configuration of the jam processing unit of the image forming apparatus 1 will be described with reference to FIGS. FIG. 3 is a diagram for mainly explaining the left door 60. FIG. 4 is a diagram for mainly explaining the fixing device 100 and the left door 60. FIG. 5 is a diagram for mainly explaining a portion connecting the fixing device 100 and the left door 60. FIG. 6 is a diagram illustrating a connection portion between the fixing device 100 and the left door 60 in the image forming apparatus 1.

  The electrophotographic image forming apparatus is provided with a fixing device 100 for fixing an unfixed toner image transferred onto a sheet to a sheet surface. 100 is passed.

  The fixing device 100 includes a fixing unit 101 that fixes a toner image, and a discharge unit 102 that discharges a sheet that has passed through the fixing unit 101.

  The fixing unit 101 includes a plate-like heater 104 that is in contact with the pressure roller 103 that rotates counterclockwise in FIG. 4 with a predetermined force.

  The pressure roller 103 is rotatably attached to a predetermined position of the fixing frame 105. Driving from a driving source (not shown) is transmitted to the pressure roller 103. The heater 104 is attached to a film guide portion integrated with the heater stay 106. A cylindrical film 108 is fitted on the outer peripheral surface of the film guide 107 in a rotatable state. This film 108 covers the heater. The heater stay 106 is attached to the fixing frame 105 so as to be movable in the vertical direction.

Both ends of the heater stay 106 are attached to the upper frame 109 and are urged toward the pressure roller 103 by two urging springs (coil springs) 110 provided at the front and rear sides via pressure plates provided at the two front and rear sides. . As a result, the heater 104 comes into contact with the pressure roller 103 through the film 108 with a predetermined pressure. The urging springs 110 are provided at both ends of the pressure roller 103, and come into contact with the heater stay 106 via pressure plates 130a and 130b that can rotate around the rotation center.
Here, the heater 104 comes into contact with the pressure roller 103 through the film 108 to form a nip portion. Further, the urging spring 110 and the pressure plates 130a and 130b constitute pressure means according to the present invention.

  FIG. 4 shows a state in which the clamping pressure for clamping the sheet is applied between the fixing unit 101 and the pressure roller 103. In this state, the urging spring 110 urges the heater stay 106 toward the pressure roller 103 via the pressure plate 130, and the heater 104 contacts the pressure roller 103 with a predetermined pressure via the film 108. .

  The discharge means 102 includes a discharge roller 112 that rotates counterclockwise in FIG. 4 and a discharge roller 113 that rotates in contact with the discharge roller 112 at a predetermined pressure.

  The discharge roller 112 is rotatably attached to a predetermined position of the fixing frame 105. The discharge roller 112 is driven by a drive source (not shown). The discharge roller 113 is rotatably attached to the lower frame 105 via the discharge upper guide member 114. The upper discharge guide member 114 is fixed to the fixing frame 105. The discharge roller 113 is attached to the discharge upper guide member 114 so as to be movable in the vertical direction, and is biased toward the discharge roller 112 by a biasing spring (not shown). Thereby, the discharge roller 113 is in contact with the discharge roller 112 at a predetermined pressure.

  4 is an inlet guide member for guiding the leading end of the sheet to the nip portion of the fixing unit 101, and reference numeral 117 is a pair of the upper discharge guide member 114 and guides the leading end of the sheet to the nip portion of the discharging unit 102. This is a lower discharge guide member. The inlet guide member 116 and the lower discharge guide member 117 are fixed to the lower frame 105.

  When the fixing device 100 is operating, driving from a driving source (not shown) is transmitted to the pressure roller 103, and the pressure roller 103 rotates counterclockwise in FIG. The film 108 rotates around the film guide 107 following the rotation of the pressure roller 103. The heater 104 is energized, and the heater 104 is adjusted to a predetermined temperature. The heat of the heater 104 is transmitted to the sheet through the film 108.

  Drive from a drive source (not shown) is transmitted to the discharge roller 112, and the discharge roller 112 rotates counterclockwise in FIG. The discharge roller 113 is rotated following the rotation of the discharge roller 112.

  The leading edge of the sheet S after the transfer of the toner image is guided to the entrance guide member 116 and enters the nip of the fixing unit 101, and the sheet S is conveyed in a state of being sandwiched by the fixing unit 101 with a predetermined pressure. During this conveyance, the sheet S is heated and pressurized, and an unfixed toner image on the sheet S is fixed on the sheet surface.

  The leading edge of the sheet S that has passed through the fixing unit 101 is guided to the discharge upper guide member 114 and the discharge lower guide member 117 and enters the nip portion of the discharge unit 102, and the sheet S is held by the discharge unit 102 with a predetermined pressure. Discharged outside the machine.

  Next, the jam processing operation will be described with reference to FIGS. FIG. 1 is a diagram for mainly explaining the fixing device 100 and the left door 60.

  A left door 60 that can be opened and closed for jamming is provided on the downstream side of the fixing device 100 in the sheet conveying direction. As shown in FIG. 6, the inside of the left door 60 constitutes a conveyance guide 60f that forms a double-sided conveyance path and an FD (face-down) sheet conveyance path.

  The image forming apparatus 1 is equipped with a duplex unit 300, and a protruding portion 300a (broken line portion) of the duplex unit travels outside the exterior surface of the left door 60 (see FIGS. 3B and 6). ).

  Further, as shown in FIG. 3A, the left door 60 has a portal shape without a wall in the space (part) 60b in which the duplex unit 300 is mounted. The left door 60 can be rotated between the image forming apparatus 1 in two places, one on each of the front side and the back side of the space for mounting the duplex unit 300 in a direction substantially perpendicular to the sheet conveyance direction. It has rotation centers 60c and 60d. The rotation centers 60c and 60d are located on the outer side (left side in FIG. 6) of the exterior surface of the left door 60 of the image forming apparatus 1 in the sheet conveyance direction.

  Since the rotation centers 60c and 60d of the left door 60 are located outside the exterior surface of the left door 60 in the sheet conveyance direction, the space 60b for escaping the protruding portion 300a of the duplex unit 300 can be reduced.

  As described above, in this configuration, when the rotation center 60c, 60d of the left door 60 is provided outside the exterior surface with respect to the sheet conveying direction, and the left door 60 rotates at the rotation center 60c, 60d, the duplex unit. An opening is provided so as not to interfere with 300. For this reason, the rotation locus of the left door 60 can be rotated in the direction of the arrow (counterclockwise) as shown in FIG. That is, even when the double-sided unit 300 is mounted, a turning locus is obtained by escaping the protruding portion 300a of the double-sided unit 300. A latch (not shown) that positions the image forming apparatus 1 is provided on the upper portion of the left door 60.

  A fixing pressure releasing means (hereinafter referred to as a fixing pressure releasing unit 400) for releasing the clamping pressure for clamping the sheet of the fixing device will be described with reference to FIGS. FIG. 7 is a diagram illustrating a state in which the left door 60 is opened in the image forming apparatus 1.

  Energizing springs 110 are provided at both ends of the fixing device 100 so as to urge the heater stay 106 toward the pressure roller 103 (nip portion) via the pressure plate 130. Thus, the heater 104 is in contact with the pressure roller 103 via the film 108 with a predetermined pressure (clamping pressure). In order to release this pressure, a fixing pressure release unit is provided.

  As shown in FIGS. 4 and 5, the fixing pressure releasing unit 400 includes pressure releasing cams 150 (150 a, 150 b) as pressure members that rotate about rotation centers 150 p provided at both ends of the fixing device 100. When the release cam 150 rotates, the pressure release lever 160 (160a, 160b) is provided as a moving member that moves obliquely in the upper right direction in FIGS. A shaft 180 as a connecting member extending in the front-rear direction is provided at the rotation center of the pressure release cams 150a, 150b, and is fixed to the front and rear pressure release cams 150a, 150b. Here, the pressure release cam 150 and the pressure release lever 160 constitute release means according to the present invention.

  An end 150q of the front pressure release cam 150 is rotatably connected to a link member (hereinafter referred to as a link) 170. The other end of the link 170 is rotatably connected to the left door 60.

  As shown in FIG. 7, when the left door 60 is opened, the fulcrum 60e of the link 170 provided on the left door 60 rotates counterclockwise as the left door 60 rotates. As a result, the link 170 moves as shown in FIG. 7, and the pressure release cam 150 rotates counterclockwise as the link 170 moves. As a result, the cam portions 150c and 150d of the pressure release cam 150 move the pressure release lever 160 in the direction of the arrow in FIG. Further, the pressure release lever 160 rotates the pressure plate 130 clockwise around the rotation center of the pressure plate in FIG. In this manner, the biasing spring 110 is compressed by moving the pressure plate 130 away from the nip portion, and the force that the heater stay 106 is biasing toward the pressure roller 103 is released.

  When the left door 60 is rotated to a predetermined angle, the rotation of the left door 60 is restricted by a stopper (not shown). In this state, the FD sheet conveyance path and the double-sided conveyance path are opened (portion indicated by L1 in FIG. 7), and the user can access the sheet S.

  By adopting such a configuration, even when the duplex unit 300 is mounted, it is possible to easily perform jam processing without moving the duplex unit 300. Further, even when the sheet stays in the fixing device 100, the jamming process can be easily performed because the clamping pressure of the fixing unit 101 is released.

  Furthermore, it is possible to sufficiently secure a space for accessing the jammed sheet staying in the double-sided conveyance path and the FD sheet conveyance path.

  When the left door 60 is closed, the link fulcrum 60e provided on the left door 60 is rotated clockwise in FIG. 7 to move the link 170, and the pressure release cam 150 is also rotated clockwise as the link 170 is moved. To do. The cam portions 150c and 150d of the pressure release cam 150 move the pressure release lever 160 obliquely downward in FIG. As the pressure release lever 160 moves, the pressing plate 130 rotates counterclockwise in FIG. 7 about the rotation center of the pressing plate 130 by the biasing force of the biasing spring 110. Then, the heater stay 106 is urged toward the pressure roller 103 and returns (restores) to a state where a predetermined clamping pressure is applied to the nip portion. By this operation, the image forming apparatus 1 returns.

{Description of fixing device replacement operation}
The replacement operation of the fixing device 100 will be described with reference to FIGS.

"Left door removal operation"
As shown in FIG. 1, the fixing device 100 is positioned in a vertical direction and a depth direction in FIG. 1 on a frame 1 f as a support portion of the image forming apparatus 1, and upstream in the sheet conveyance direction (in FIG. 1). The right side) is regulated. A fixing pressure releasing unit 400 is fixed to the image forming apparatus 1 by a fixing unit (hereinafter referred to as a locking unit) on the downstream side in the sheet conveying direction of the fixing device 100 (left side in FIG. 1). In this way, the fixing device 100 is fixed to the image forming apparatus 1 by restricting the left side of the fixing device 100.

  Next, the replacement operation of the fixing device 100 will be described.

  As shown in FIG. 1A, first, the left door 60 is opened in the same manner as the jam handling operation.

  As shown in FIG. 1B, the link 170 is rotatably supported by a pressure release cam 150 of the fixing pressure release unit. Next, as shown in FIG. 1C, the link 170 is rotated in the direction of the arrow to remove the link 170 from the left door fulcrum 60e. The engaging portion 170b that engages with the fulcrum 60e of the left door of the link 170 is substantially U-shaped and has a shape that can be removed in the direction of the arrow.

  When the link 170 is removed, the left door 60 can further rotate counterclockwise in FIG.

  FIG. 8 is an explanatory diagram of a configuration in which the left door 60 is attached to the image forming apparatus main body. FIG. 9 is a diagram illustrating a case where a space can be secured on the lower side of the image forming apparatus 1.

  On the front side of the apparatus, the rotation center 60d of the left door 60 is composed of a shaft member, and is rotatably inserted into the hole 202 of the image forming apparatus main body. Further, the rotation center 60c of the left door 60 on the back side of the apparatus has a substantially arc shape with a notch, and has a horizontal part on the top and bottom provided in the main body of the image forming apparatus, and the horizontal (left and right) direction is approximately. A circular arc shaft 201 is rotatably fitted.

  The rotation center 60d on the front side of the left door 60 is bent inward (backward direction in FIG. 8) to be removed from the hole 202 of the apparatus body, and the rotation center 60c on the back side of the left door 60 has a notch portion from the shaft 201. It can be removed from the image forming apparatus 1 by moving it in the direction of removal, that is, on the left side of the apparatus (left side in FIGS. 1C and 8).

  The left door 60 is removed in order to secure a space for removing a fixing pressure releasing unit 400 and a fixing device 100 described later from the image forming apparatus. As shown in FIG. 9, when a space can be secured on the lower side of the image forming apparatus 1, it is also possible to cope with the problem by further rotating the left door 60 without removing the left door 60.

“Removing operation of fixing pressure release unit and fixing device”
10 and 11 show a state in which the fixing device 100 is fixed to the image forming apparatus by fixing the fixing pressure releasing unit 400 to the image forming apparatus.

  As described above, the fixing pressure releasing unit 400 is provided with the pressure releasing levers 160a and 160b, the shaft 180, the pressure releasing cams 150a and 150b, and the link 170 (see FIGS. 4 and 5). As described above, the pressure release lever 160 is provided so as to be movable obliquely in the upper right direction in FIG. 4 by the rotation of the pressure release cam 150, and the pressure plates 130a and 130b are rotated in accordance with this movement. Become.

  Furthermore, levers 410 and 420 as locking means for the image forming apparatus, and lock shafts 411 and 421 as lever members integrated with the levers 410 and 420 are provided. As shown in FIG. 11, by rotating the lever 410 by 90 degrees, the lock shaft 411 engages with a lock portion 601 as a locking portion of the image forming apparatus, and the fixing pressure releasing unit 400 is supported and fixed to the image forming apparatus. Is done. With such a configuration, the fixing pressure releasing unit 400 is detachable from the image forming apparatus. Although not shown, the opposite side of the apparatus has the same configuration. That is, by rotating the back side lever 420 by 90 degrees, the lock shaft 421 is engaged with the back side lock portion 602 of the image forming apparatus. Note that the lock shaft may be provided in the image forming apparatus, and the lock portion for locking the lock shaft may be provided in the fixing pressure release unit 400.

  In this way, the fixing pressure release unit 400 can be supported and fixed to the image forming apparatus by a lock lever mechanism that does not use a tool, that is, by rotating the levers 410 and 420, so that the usability is extremely excellent. Yes. Further, in order to fix the fixing pressure release unit 400 on the downstream side of the fixing device to the image forming device 1 without fixing the fixing device itself to the image forming device 1, an access unit to the fixing device is further provided outside the device. And easy for users to access.

  FIG. 23 is a diagram for explaining a method of fixing the fixing pressure releasing unit 400 to the image forming apparatus.

  In this configuration, the fixing pressure releasing unit 400 is fixed to the image forming apparatus with a lock member. However, as shown in FIG. 23, the fixing pressure releasing unit 400 may be fixed to the fixing pressure releasing frame 450 with a screw (screw) 440 having a drop-off preventing function. As a drop-off preventing function, for example, a groove may be provided in the screw 440 main body, and an E-ring 441 may be attached to the groove. As a result, the screw 440 does not fall off the fixing pressure release frame 450. Attachment to the image forming apparatus is performed by screwing into a screw hole 611a of a frame 611 of the image forming apparatus. The opposite side also has the same configuration. In this case, the user needs a driver when removing the fixing pressure release unit 400, but there is an advantage that the cost of the screw is lower than that of the lock member.

  FIG. 12 shows a state where the front cover 412 of the fixing pressure releasing unit 400 is removed. FIG. 13 is a diagram for explaining a case where the fixing pressure releasing unit 400 is removed from the image forming apparatus 1.

  As shown in FIG. 12, a link spring 171 is provided between the link 170 and the pressure release cam 150, and the link 170 is urged in the arrow direction. Further, a pressure release cam spring 151 is provided between the pressure release cam 150 and the fixing pressure release frame 401 and is urged in the arrow direction (clockwise direction). Because of these springs, when the fixing pressure releasing unit 400 is removed from the image forming apparatus 1 as shown in FIG. 13, the force from the fixing device is released, and the pressure releasing cam 150 and the link 170 are used when the fixing pressure is released. The position (FIG. 7) returns to the home position shown in FIGS.

  FIG. 14 is an explanatory diagram of the positioning unit of the fixing device 100 and the fixing pressure release unit 400.

  The fixing device 100 is provided with positioning holes 100a and 100b, and the fixing pressure releasing unit 400 is provided with positioning bosses 401a and 401b. The bosses of the fixing pressure releasing unit 400 are fitted into the holes of the fixing device 100 to determine the positions. Further, the surfaces of the hatched portions of the fixing device 100 and the fixing pressure releasing unit 400 are in contact with each other, so that the fixing pressure releasing unit 400 is sandwiched between the image forming apparatus 1 and fixed. In FIG. 14, the hatched portions 100 c and 100 d of the fixing device 100 come into contact with the hatched portions 401 c and 401 d of the fixing pressure release unit 400, respectively.

  As shown in FIG. 13, the fixing pressure releasing unit 400 is moved to the left side in the drawing and removed from the image forming apparatus 1, so that the fixing device 100 can also be moved and removed in the same direction (left direction in the drawing). This is because the fixing device 100 does not have a fixing means for the image forming apparatus 1, so that the fixing device 100 can be detached from the image forming apparatus 1 by removing the fixing pressure releasing unit 400 (in the image forming apparatus 1). This is because the state is not supported.

"Replacing the fixing device and installing the left door"
FIG. 15 is a diagram for explaining a case where the left door 60 is attached to the image forming apparatus 1.

  First, after the replacement new fixing device is attached, the fixing pressure releasing unit 400 is attached and locked to the image forming apparatus 1.

  Next, the left door 60 is attached to the image forming apparatus. In this case, the reverse operation described in FIG. 8 is performed. That is, after the rotation center 60 d of the left door 60 is inserted into the hole 202, the rotation center 60 c is inserted into the shaft 201. Thereafter, as shown in FIG. 15A, the left door 60 is rotated clockwise.

  The vicinity of the fulcrum 60e as the engaging part of the link 170 of the left door 60 has a structure as shown in FIG. 15B, and as a guiding part extending from the fulcrum 60e of the link 170 shown by a hatched part. The guide surface 60z is provided. The link 170 is provided with a projection shape 170a corresponding to the guide surface 60z. When the left door 60 is closed, the projection shape 170a abuts on the guide surface 60z, and the link 170 has its rotation center 170p (150q). It is configured to rotate around the center. Here, the guide surface 60z only needs to be provided at a position where the protruding shape 170a abuts when the left door 60 is closed and guides the engaging portion 170b of the link 170 to the fulcrum 60e. Here, the fulcrum 60e and the guide surface 60z constitute a contact / separation part according to the present invention.

  FIG. 16 is an explanatory diagram of the closing operation of the left door 60 and the rotating operation of the link 170.

  When the left door 60 is closed, the protrusion 170a of the link 170 slides on the guide surface 60z of the left door 60 and rotates clockwise in the direction of the arrow in FIG. 16A, and approaches the fulcrum 60e of the link 170. Go. As shown in FIG. 16B, when the left door 60 is further closed, the U-shaped opening of the engaging portion 170 b of the link 170 is fitted into the fulcrum 60 e of the link 170. Further, in the state of FIG. 16C, the corner portion 60 x as the auxiliary portion of the left door 60 is positioned downward so that the substantially U-shaped engaging portion 170 b of the link 170 is fitted to the fulcrum 60 e of the link 170. By pushing, the connection state of the left door 60 and the pressure release unit 400 shown in FIG.

  With this configuration, it is possible to prevent the link 170 from being forgotten to be connected to the left door 60 after the fixing device 100 is replaced. In other words, it is possible to prevent the fixing pressure from being released when the jam processing operation is performed after the replacement of the fixing device 100 and the jam processing performance to be deteriorated.

  According to this configuration, when the fixing device 100 is replaced, since the fixing pressure releasing unit 400 is configured as a unit different from the fixing device 100, only the fixing device 100 can be replaced. Compared with the replacement in the case where the fixing device is provided with fixing pressure releasing means, the fixing device as the replacement unit can be made inexpensive.

  In this embodiment, the fixing device itself is not fixed to the image forming apparatus 1, and the pressure releasing unit 400 provided at a position downstream of the fixing device 100 in the sheet conveying direction, that is, at a position close to the left door 60 is used. The fixing device 100 is sandwiched and fixed. For this reason, in this embodiment, compared to a configuration in which the fixing device itself is fixed to the image forming apparatus, the fixing unit accessed by the user can be positioned on the outer side of the image forming apparatus. There is. In particular, this is effective when the fixing device 100 is provided at a position inside the image forming apparatus 1 as in this embodiment.

  Further, after the replacement of the fixing device 100, the link 170 provided in the fixing pressure releasing unit 400 is connected to the left door 60 in conjunction with the mounting operation of the left door 60. For this reason, forgetting to attach the link 170 after replacement of the fixing device 100 can be prevented, and the state where the fixing pressure is not released after the jam processing can be eliminated.

  FIGS. 17-21 is explanatory drawing of Example 2 of this invention. 17-19 is a figure for demonstrating the inner guide 75 of a present Example. 20 and 21 are diagrams for explaining the fixing pressure release unit of the present embodiment.

  In the first embodiment, the conveyance path is provided inside the left door 60. However, in the configuration of the first embodiment, as illustrated in FIG. 7, the jam processing space L1 is small with the left door 60 opened. Therefore, in this embodiment, an inner guide 75 is provided in which the lower conveyance path provided in the left door 60 in the first embodiment is separated, and the conveyance path is formed by the left door 70 and two parts. (See FIG. 20).

  The center 75 of the inner guide 75 is provided at a position 75p different from that of the left door 70, and is biased in a direction that rotates counterclockwise in FIG. 21 (a direction in which the left door 70 opens) by biasing means (not shown). Has been. In the home position, the abutting portion 71 of the left door 70 is in contact with the inner guide 75 so that the position of the sheet conveyance path is determined.

  In this embodiment, as shown in FIGS. 17 and 18, the fixing pressure release unit is provided with the center of rotation of the inner guide 75, and the inner guide 75 is provided in the fixing pressure release unit 500. When the fixing device 100 is replaced, the pressure releasing unit 500 having the inner guide 75 is removed. Since other configurations are the same as those of the first embodiment, description thereof is omitted.

  As shown in FIG. 20, when the left door 70 is opened, the abutting portion 71 of the left door 70 escapes to the outside of the apparatus main body, so that the inner guide 75 is urged by the urging means, and the rotation center 75p is the center. Rotate counterclockwise to fall down and stop at a predetermined position. As in the first embodiment, the fulcrum of the left door 70 is rotated by the pressure releasing means, so that the link 170 is moved as shown in FIG. 20, and the pressure releasing cam 150 is also rotated counterclockwise by the link 170. The cam portion of the pressure release cam 150 moves the pressure release lever 160 obliquely upward in FIG. 20, and the pressure release lever 160 rotates the pressure plate 130 clockwise around the rotation center of the pressure plate, thereby By compressing, the force urging the heater stay 106 toward the pressure roller 103 is released.

  According to this configuration, the jam processing space L2 can be secured larger than L1 of the first embodiment.

  Next, an operation for closing the left door 70 will be described with reference to FIG.

  When the left door 70 is closed, the link fulcrum 70e provided on the left door 70 rotates, so that the link moves as shown in FIG. 21, and the pressure release cam 150 also rotates clockwise as the link 170 moves. As shown in FIG. 19, an inner guide return cam 190 is fixed to a shaft 180 that fixes the pressure release cams 150 at the front and rear, and the shaft 180 and the inner guide are rotated by the rotation of the pressure release cam 150. The return cam 190 also rotates clockwise, causing the inner guide 75 to rotate clockwise to a predetermined angle.

  When the left door 70 is further rotated, the abutting portion 71 of the left door 70 comes into contact with the inner guide 75, and the inner guide 75 is further rotated clockwise to return to the home position.

  In conjunction with this operation, the cam portion of the pressure release cam 150 moves the pressure release lever 160 obliquely downward in FIG. 21 in the same manner as in the first embodiment, so that the pressure release lever 160 escapes. Thus, the pressing plate 130 is rotated counterclockwise around the rotation center of the pressing plate 130 by the biasing spring, and the heater stay 106 is biased to the pressing roller 103 side. By this operation, the image forming apparatus 1 returns.

According to this embodiment, the sheet conveying path is formed by the left door 70 and the inner guide 75 having different rotation centers. In addition to the effect of the first embodiment, a wide jam processing space is secured. The fixing device 100 can be replaced.

  FIG. 22 is a diagram for explaining a third embodiment of the present invention. Here, only parts different from the above-described embodiment will be described.

  In the first and second embodiments described above, the link 170 is rotatably provided in the fixing pressure release units 400 and 500 and is configured to be detachable from the left doors 60 and 70.

  Here, in the connecting portion between the fixing pressure release unit and the link, when it is easy to configure a space for the user to remove the link, the attachment / detachment of the link is performed between the fixing pressure release unit and not the left door. Will improve usability.

  Therefore, in this embodiment, as shown in FIG. 22, a link is provided rotatably on the left door, and is configured to be detachable from the fixing pressure release unit.

  According to the present exemplary embodiment, the position at which the link is removed (the link contact / separation portion) can be appropriately set to a suitable position according to the specifications of the image forming apparatus. Thereby, usability can be improved.

FIG. 3 is a diagram for explaining the first embodiment. Explanatory drawing of conveyance of Example 1. FIG. FIG. 3 is a diagram for explaining the first embodiment. FIG. 3 is a diagram for explaining the first embodiment. FIG. 3 is a diagram for explaining the first embodiment. 1 is a main sectional view of Example 1. FIG. 1 is a main sectional view of Example 1. FIG. FIG. 3 is a diagram for explaining the first embodiment. FIG. 3 is a diagram for explaining the first embodiment. FIG. 3 is a diagram for explaining the first embodiment. FIG. 3 is a diagram for explaining the first embodiment. FIG. 3 is a diagram for explaining the first embodiment. FIG. 3 is a diagram for explaining the first embodiment. FIG. 3 is a diagram for explaining the first embodiment. FIG. 3 is a diagram for explaining the first embodiment. FIG. 3 is a diagram for explaining the first embodiment. FIG. 6 is a diagram for explaining the second embodiment. FIG. 6 is a diagram for explaining the second embodiment. FIG. 6 is a diagram for explaining the second embodiment. FIG. 6 is a diagram for explaining the second embodiment. FIG. 6 is a main cross-sectional view of Example 2. FIG. 6 is a diagram for explaining Example 3; FIG. 3 is a diagram for explaining the first embodiment.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Image forming apparatus 2,3 Paper feed cassette 4,5 Feed roller 6,7 Separation pad 8 Sheet conveyance path 9 Registration roller 10 Drum 11 Cartridge 14 Writing scanner 30 Sheet discharge part 51 Scanner part 57 Manuscript table glass 60 Left door 70 Left door 75 Inner guide 100 Fixing device 150 Pressure release cam 160 Pressure release arm 170 Link 180 Shaft 190 Inner guide return cam 300 Duplex unit 400 Fixing pressure releasing unit 500 Fixing pressure releasing unit

Claims (14)

An image forming unit for transferring a toner image obtained by developing the electrostatic latent image formed on the image carrier to a sheet;
Fixing means for fixing the toner image formed on the sheet in a state where the sheet is held at a predetermined pressure at the nip portion;
An opening and closing member provided to be openable and closable with respect to the apparatus body, and exposing the inside of the apparatus body when opened;
In an image forming apparatus comprising:
Fixing pressure release having a release means provided on the downstream side of the fixing means in the sheet conveying direction so as to be detachable from the apparatus main body and releasing the clamping pressure of the fixing means on the sheet in conjunction with the opening operation of the opening / closing member. Means,
Fixing means for fixing the fixing pressure releasing means to the apparatus body;
With
The fixing means is fixed to the apparatus main body by the fixing means in a state where the fixing means is sandwiched between a support portion provided in the apparatus main body and the fixing pressure releasing means. Is supported and fixed to the apparatus main body.   The image forming apparatus according to claim 1, wherein the release unit restores the clamping pressure of the fixing unit with respect to the sheet in conjunction with the closing operation of the opening / closing member. The fixing unit includes a pressing unit that applies pressure to the nip portion,
The image forming apparatus according to claim 1, wherein the release unit releases the nipping pressure on the sheet by moving the pressurizing unit in a direction away from the nip portion. The fixing pressure releasing means includes a link member that connects the opening / closing member and the releasing means,
The link member releases the pinching pressure of the fixing unit on the sheet by moving the pressing unit by operating the release unit in conjunction with the opening operation of the opening / closing member. The image forming apparatus according to 3. The release means is
A pivot member connected to the link member and pivoting in conjunction with the movement of the link member;
A moving member that moves the pressurizing means in accordance with the rotating operation of the rotating member;
The image forming apparatus according to claim 4, further comprising:   The image forming apparatus according to claim 5, wherein the rotation member is provided on each side of the sheet conveyance region in a width direction of the sheet substantially orthogonal to the sheet conveyance direction. A connecting member that connects the rotating members respectively provided on both sides of the sheet conveying region;
The image forming apparatus according to claim 6, wherein the link member is connected to any one of the rotating members provided on both sides of the sheet conveyance region. The link member is
It is provided so as to be able to contact and separate with respect to the opening / closing member or the release means,
When the opening and closing member is in an open state and the opening and closing member and the releasing means are in a disconnected state, the opening and closing member and the releasing means are connected in conjunction with a closing operation of the opening and closing member. The image forming apparatus according to claim 4, wherein the image forming apparatus is an image forming apparatus. Provided in the opening / closing member or the releasing means, and in the contact / separation portion where the link member is contacted / separated, a guide portion for guiding the link member and an engagement portion engaging with the link member are provided. And
When the opening / closing member is in an open state and the opening / closing member and the releasing means are in a disconnected state, the link member abuts on the guide portion with the closing operation of the opening / closing member, and then the engaging portion The image forming apparatus according to claim 8, wherein the image forming apparatus is connected to the opening / closing member or the release unit at the engagement portion.   The image forming apparatus according to claim 9, further comprising an auxiliary unit that assists an engaging operation of engaging the link member guided by the guide unit with the engaging unit. A part of the sheet conveyance path on the downstream side of the fixing unit is provided in the opening / closing member,
The image forming apparatus according to claim 1, wherein the sheet conveying path is exposed when the opening / closing member is opened.   12. A part of the sheet conveyance path provided in the vicinity of the fixing unit in the sheet conveyance path on the downstream side of the fixing unit is provided in the fixing pressure releasing unit. The image forming apparatus described. The fixing means includes
A lever member provided on any one of the apparatus main body and the fixing pressure releasing means;
A locking portion that is provided on the other of the apparatus main body and the fixing pressure releasing means and that locks the lever member;
The image forming apparatus according to claim 1, further comprising:   The image forming apparatus according to claim 1, wherein the fixing unit includes a screw having a drop-off preventing unit.

Images