Image forming apparatus

Abstract

To provide an image forming apparatus that can stably maintain an open state of a shutter and a closed state of the shutter both when the shutter is open and when the shutter is closed.SOLUTION: An image forming apparatus 1 comprises: a fuser 6 that has a heating unit 61 and a pressure roller 62 forming a nip NP with the heating unit 61, and fixes a toner image to a sheet S; a shutter 64 that is displaceable to a closed position where it covers a part of the heating unit 61 and an open position where it opens the part of the heating unit 61; and an urging member 9 that urges the shutter 64 to be held at the closed position when the shutter 64 is at the closed position and urges the shutter 64 to be held at the open position when the shutter 64 is at the open position.SELECTED DRAWING: Figure 13

Description

[Technical field]

[0001] The present invention relates to an image forming apparatus. [Background technology]

[0002] 2. Description of the Related Art Conventionally, in an image forming apparatus having a removable cartridge, a shutter is provided in front of the fixing unit having a heating portion in order to prevent a user's hand from touching the fixing unit.

[0003] For example, the image forming apparatus disclosed in Patent Document 1 is provided with a link member that is connected to the shutter and can abut against the cartridge, and when the cartridge is mounted, the link member abuts against the cartridge and moves, and the shutter opens in accordance with the movement of the link member. In this case, the shutter is biased in the closing direction by a biasing spring. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Patent No. 6961471 Summary of the Invention [Problem to be solved by the invention]

[0005] As described above, the shutter is biased only in the closing direction by the biasing spring, and even when the shutter is in an open state, a biasing force in the closing direction acts on the shutter, which may cause the open state of the shutter to become unstable.

[0006] Therefore, the present invention provides an image forming apparatus that can stably maintain the shutter in both the open and closed states when the shutter is in the open state and when the shutter is in the closed state. [Means for solving the problem]

[0007] The image forming apparatus that solves the above problem has the following features.

[0008] That is, the image forming apparatus is equipped with a fixing unit having a heating unit and a pressure unit that forms a nip with the heating unit and fixes a toner image to a sheet, a shutter that is displaceable between a closed position that covers part of the heating unit and an open position that opens part of the heating unit, and a biasing member that, when the shutter is in the closed position, biases the shutter to be held in the closed position, and, when the shutter is in the open position, biases the shutter to be held in the open position.

[0009] This makes it possible to stably hold the shutter in the open position in an open state and to stably hold the shutter in the closed position in a closed state by using a single biasing member.

[0010] The shutter device further includes a switching mechanism that switches the biasing direction of the biasing member between a biasing direction for holding the shutter at the closed position and a biasing direction for holding the shutter at the open position.

[0011] As a result, the switching mechanism and the biasing member can stably hold the shutter in the open position in an open state, and can stably hold the shutter in the closed position in a closed state.

[0012] The switching mechanism further includes a link connected to the shutter and displaceable between a first position in which the shutter is displaced to a closed position and a second position in which the shutter is displaced to an open position, and the biasing member biases the link.

[0013] This allows the opening and closing of the shutter and the holding of the shutter in the closed and open positions to be performed by a common member.

[0014] The biasing member has a spring that biases the link, and a pressing portion that is connected to the spring and presses the link.

[0015] This allows the link to be stably pressed by the pressing portion connected to the spring.

[0016] The link also has a first portion that abuts against the pressing portion when the link is in the first position and converts the bias direction of the spring to a direction in which the link moves from the second position to the first position, and a second portion that abuts against the pressing portion when the link is in the second position and converts the bias direction of the spring to a direction in which the link moves from the first position to the second position.

[0017] This makes it possible, by the biasing force of a single spring, to stably hold the shutter in the closed position in the closed state, and to stably hold the shutter in the open position in the open state.

[0018] Further, the first portion of the link is a first inclined surface inclined with respect to the movement direction of the link, and the second portion of the link is a second inclined surface inclined with respect to the movement direction of the link, and the inclination direction of the first inclined surface and the inclination direction of the second inclined surface are different.

[0019] This allows the first and second portions to be easily formed into the link.

[0020] In addition, the spring of the biasing member biases the pressing portion downward, the first inclined surface of the link has an inclined shape that rises along the movement direction of the link from the second position toward the first position, and the second inclined surface of the link has an inclined shape that rises along the movement direction of the link from the first position toward the second position.

[0021] This makes it possible to efficiently convert the biasing direction of the spring between the direction in which the link is directed from the first position to the second position and the direction in which the link is directed from the second position to the first position.

[0022] The pressing portion is an arm having a rotation center at one end and a contact portion at the other end that contacts the link.

[0023] This allows the pressing portion to smoothly press the link.

[0024] The device further includes an operating member operable by a user to displace the link.

[0025] This allows the shutter to be opened and closed in conjunction with a user's operation.

[0026] Further, the operating member is a cartridge that is detachable from the image forming device, and when the cartridge is attached to the image forming device, the shutter moves to the open position, and when the cartridge is removed from the image forming device, the shutter moves to the closed position.

[0027] This allows the shutter to be moved between the open position and the closed position in accordance with the operation of mounting or removing the cartridge to or from the image forming apparatus.

[0028] The cartridge also has a photosensitive drum that rotates around a drum shaft, and the link has a contact piece that abuts against the drum shaft, a first link that abuts against the urging member, and a second link that is rotatably connected to the first link and also rotatably connected to the abutment piece.

[0029] As a result, the movement of the abutment piece due to the drum shaft is transmitted to the first link via the second link, so that even if the distance between the cartridge mounting position in the image forming device and the shutter is large, the driving force can be efficiently transmitted from the abutment piece to the shutter.

[0030] In addition, the drum shaft of the cartridge being removed from the image forming device abuts against the abutment piece and presses the first link in a direction from the second position to the first position, and before the first link, which is pressed by the drum shaft and moves from the second position to the first position, reaches the first position, the drum shaft and the abutment piece separate, and after the drum shaft and the abutment piece separate, the first link is urged in a direction from the second position to the first position by the urging force of the urging member and reaches the first position.

[0031] As a result, when the first link reaches the first position and the shutter moves to the closed position, the abutment piece of the link and the cartridge are separated, so that the shutter can be stably maintained in the closed position regardless of the position of the cartridge after it has separated from the abutment piece.

[0032] The shutter further includes a restricting surface that comes into contact with the shutter in the closed position to restrict the position of the shutter.

[0033] As a result, when the shutter moves to the closed position, it comes into contact with the restricting surface and is restricted from moving any further, so that the shutter can be held in the closed position.

[0034] Moreover, the link is configured not to move from the first position toward the second position when a force toward the open position is applied to the shutter in the closed position.

[0035] As a result, even if the shutter, which is in the closed position, moves toward the open position, the link does not move, so that subsequent operation of the link is prevented from being hindered.

[0036] The link also has a shutter link connected to the shutter and moving the shutter between the open position and the closed position, a link cam connected to the shutter link and movable between the first position and the second position, and a link spring that moves along with the movement of the link cam to press the shutter link, and when the link cam is in the first position, the link spring abuts against the shutter link and presses the shutter link in a direction in which the shutter moves to the closed position, and when the link cam is in the first position, when the shutter moves from the closed position toward the open position, the link spring abutting against the shutter link elastically deforms and the link cam maintains its state in the first position.

[0037] As a result, when the link cam is in the first position and the shutter, which is in the closed position, moves toward the open position, the link spring in contact with the shutter link elastically deforms, causing the link cam to remain in the first position without moving, thereby preventing subsequent link operation from being hindered.

[0038] The image forming device also has an opening and an opening / closing cover as an operating member that can be moved between a closed position that closes the opening and an open position that opens the opening, and when the opening / closing cover is in the closed position, the shutter moves to the open position, and when the opening / closing cover is in the open position, the shutter moves to the closed position.

[0039] This allows the shutter to move between the open and closed positions in conjunction with the opening and closing of the opening and closing cover. Effect of the Invention

[0040] According to the present invention, a single biasing member can stably hold a shutter in an open position in an open state, and can stably hold a shutter in a closed position in a closed state. [Brief description of the drawings]

[0041] [Figure 1]FIG. 2 is a central cross-sectional view showing the image forming apparatus. [Diagram 2] FIG. 2 is a perspective view showing the image forming apparatus with the front cover in an open position. [Diagram 3] FIG. [Figure 4] FIG. 2 is a perspective view showing a heating unit and a pressure roller of the fixing unit. [Diagram 5] FIG. 2A is a perspective view showing the fixing unit when the shutter is in a closed position, and FIG. 2B is a perspective view showing the fixing unit when the shutter is in an open position. [Figure 6] FIG. 2A is a side view showing the fixing unit when the shutter is in a closed position, and FIG. 2B is a side view showing the fixing unit when the shutter is in an open position. [Figure 7] FIG. 2A is a side cross-sectional view showing the fixing unit when the shutter is in a closed position, and FIG. 2B is a side cross-sectional view showing the fixing unit when the shutter is in an open position. [Figure 8] FIG. 2A is a front view showing the right end portion of the fixing unit when the shutter is in a closed position, and FIG. 2B is a front view showing the right end portion of the fixing unit when the shutter is in an open position. [Figure 9] FIG. 2 is a perspective view showing a process cartridge. [Figure 10] FIG. 2 is a side view showing the process cartridge. [Figure 11] FIG. 4 is a side view showing the left side surface of the first main body frame. [Figure 12] FIG. 4 is a side view showing the right side surface of the first main body frame. [Figure 13] 13 is a side view showing the link in a state in which the first boss of the abutment piece is located in the middle of the abutment piece rail and the second boss is located in the front of the abutment piece rail. FIG. [Figure 14] A side view showing the first main body frame in a state where the process cartridge is located at the installation start position, the first boss of the abutment piece is located at the middle of the abutment piece rail, and the second boss is located at the front of the abutment piece rail. [Figure 15] FIG. [Figure 16]13 is an enlarged side view showing a state in which the drum shaft that has entered the center of the cartridge rail abuts against a first boss of the abutment piece. FIG. [Figure 17] 13 is a side view showing the link in a state in which the drum shaft is in contact with the contact piece, a rear portion of the first boss of the contact piece is located at the rear of the contact piece rail, and the second boss is located at the center of the contact piece rail. [Figure 18] This is a side view showing the first main body frame in a state in which the drum shaft is in contact with the abutment piece, a rear portion of the first boss of the abutment piece is located at the rear of the abutment piece rail, and the second boss is located at the center of the abutment piece rail. [Figure 19] 1 is an enlarged side view showing a state in which the drum shaft is in contact with the contact piece, a rear portion of the first boss of the contact piece is located at the rear of the contact piece rail, and the second boss is located at the center of the contact piece rail. [Figure 20] 13 is a side view showing the link in a state in which the drum shaft is in contact with the contact piece, the first boss of the contact piece is located at the rear part of the contact piece rail, and the second boss is located at the center part of the contact piece rail. FIG. [Figure 21] 1 is a side view showing the first main body frame in a state in which the drum shaft is in contact with the abutment piece, the first boss of the abutment piece is located at the rear of the abutment piece rail, and the second boss is located at the middle of the abutment piece rail. [Figure 22] 13 is an enlarged side view showing a state in which the drum shaft has moved from the center to the rear of the cartridge rail and the abutment piece and the drum shaft are separated from each other. FIG. [Figure 23] 20 is a side view showing a state in which the linear motion link has moved rearward from the position shown in FIG. 19 due to a pressing force from the pressing arm. FIG. [Figure 24] 22 is an enlarged side view showing a state in which a first boss of the abutment piece has moved rearward from the position shown in FIG. 21. FIG. [Diagram 25] 13 is a side view showing the first main body frame in a state where the process cartridge has reached the mounting position after the drum shaft has been separated from the contact piece. FIG. [Figure 26] 13 is an enlarged side view of the first main body frame, showing a state in which the drum shaft reaches the center of the cartridge rail and abuts against the second boss of the abutment piece. FIG. [Figure 27]13 is an enlarged side view of the first main body frame, showing how the second boss of the contact piece in contact with the drum shaft moves from the center to the front of the contact piece rail. FIG. [Figure 28] FIG. 11 is a side view showing the link in a state where the second boss of the abutment piece abutting against the drum shaft moves from the middle to the front of the abutment piece rail, causing the linear link to move forward, and the pressure arm moves from the second pressed surface of the linear link to the first pressed surface. [Figure 29] 13 is an enlarged side view of the first body frame, showing a state in which the first boss of the abutment piece moved by the drum shaft is located in the middle of the abutment piece rail and the second boss is located in the front of the abutment piece rail. FIG. [Diagram 30] 13 is a side view showing a state in which the linear link has moved forward and the pressing arm has moved from the first pressed surface of the linear link to the third pressed surface of the linear link. FIG. [Diagram 31] 13 is an enlarged side view of the first body frame, showing a state in which the abutment piece has moved until the second boss is positioned at the front part of the abutment piece rail and the abutment piece and the drum shaft are separated from each other. FIG. [Diagram 32] 13 is a side view showing a state in which the linear link has moved forward by a pressing force from a pressing arm until the shutter moves to a closed position. FIG. [Diagram 33] 32 is an enlarged side view of the first main body frame showing a state in which the linear link has moved forward due to the pressing force from the pressing arm, and the second boss of the abutment piece has moved forward along the front part of the abutment piece rail from the position shown in FIG. [Diagram 34] FIG. 11 is a side view showing a state in which, when the link is in a first position and the shutter is moving to a closed position, the arm portion of the coil spring is elastically deformed and moved upward when the shutter link moves in a direction toward the open position of the shutter. [Diagram 35] FIG. 11 is a side view showing an operating member for moving a link according to the second embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0042] Next, an embodiment of the present invention will be described with reference to the accompanying drawings.

[0043] [Image forming equipment] An image forming apparatus 1 shown in FIG. 1 is one embodiment of an image forming apparatus equipped with a sheet conveying device according to the present invention, and is a laser printer that forms an image on a sheet S by electrophotography.

[0044] In the following description, the right side in Fig. 1 is defined as the front side of the image forming apparatus 1, the left side in Fig. 1 is defined as the rear side of the image forming apparatus 1, the front side of the paper in Fig. 1 is defined as the left side of the image forming apparatus 1, and the back side of the paper in Fig. 1 is defined as the right side of the image forming apparatus 1. In addition, the upper and lower sides in Fig. 1 are defined as the upper and lower sides of the image forming apparatus 1, respectively.

[0045] The image forming apparatus 1 includes an apparatus main body 2, a paper feed section 3, an image forming section 5, a fixing unit 6, and a paper discharge section .

[0046] The device body 2 houses a paper feed section 3, an image forming section 5, a fixing unit 6, and a paper discharge section 7. An opening 2A is open at the front of the device body 2, and the device body 2 has a front cover 21 that can open and close the opening 2A. The front cover 21 is configured to be rotatable about a rotation shaft 21a at the lower end, and can move between a closed position where the opening 2A is closed and an open position where the opening 2A is opened by rotating about the rotation shaft 21a. The opening 2A is an example of an opening, and the front cover 21 is an example of an operating member operated by a user.

[0047] The paper feed unit 3 includes a paper feed tray 10 that supports the sheet S, a sheet transport unit 30, a transport roller pair 34, and a registration roller 35a. The paper feed unit 3 is disposed at the bottom of the device body 2, and transports the sheet S supported by the paper feed tray 10 to the image forming unit 5. The image forming device 1 has a transport path P for the sheet S that runs from the paper feed unit 3 to the paper discharge unit 7 via the image forming unit 5.

[0048] The paper feed tray 10 has a pressure plate 12 and a pressing plate 13. The pressure plate 12 is a plate-shaped member that supports the sheets S from below. The pressure plate 12 is rotatable about a rotation fulcrum 12a at the rear end, and can be raised and lowered between a lowered position and an upper position by rotating about the rotation fulcrum 12a. The pressing plate 13 is located below the pressure plate 12, and can raise and lower the pressure plate 12 between the lowered position and the upper position.

[0049] The sheet conveying section 30 is a conveying mechanism that separates and takes out the sheets S supported by the paper feed tray 10 one by one, and conveys the sheets S toward the image forming section 5, and includes a paper feed roller 31, a separation roller 32, and a separation pad 33.

[0050] The paper feed roller 31 is a roller for sending the sheet S supported by the paper feed tray 10 toward the separation roller 32. The separation roller 32 is disposed downstream of the paper feed roller 31 in the sheet conveying direction, and the separation pad 33 is disposed opposite to the separation roller 32 and is biased toward the separation roller 32.

[0051] The sheets S sent by the paper feed roller 31 toward the separation roller 32 are separated one by one between the separation roller 32 and the separation pad 33. The separated sheets S are sent to a conveying path P.

[0052] The sheet S sent to the conveying path P is conveyed toward the image forming unit 5 by the conveying roller pair 34, the registration roller 35a, and the pinch roller 35b arranged opposite the registration roller 35a. The registration roller 35a regulates the movement of the leading edge of the conveyed sheet S, temporarily stops the sheet S, and then conveys the sheet S toward the image forming unit 5 at a predetermined timing.

[0053] The image forming unit 5 is disposed downstream of the paper feed unit 3 in the sheet transport direction, and forms an image on the sheet S transported from the paper feed unit 3. The image forming unit 5 includes a process cartridge 50 that transfers an image onto the surface of the sheet S transported from the paper feed unit 3, a transfer roller 55 that is disposed opposite a photosensitive drum 54 of the process cartridge 50, and an exposure unit 56 that exposes the surface of the photosensitive drum 54. The process cartridge 50 is an example of a cartridge that is detachable from the image forming apparatus, and the cartridge is an example of an operating member operated by a user.

[0054] The process cartridge 50 is disposed above the paper feed unit 3 in the apparatus main body 2, and includes a developer storage chamber 51, a supply roller 52, a developing roller 53, and a photosensitive drum 54. The process cartridge 50 supports a pinch roller 35b.

[0055] The process cartridge 50 includes a drum cartridge having a photosensitive drum 54, and a developer cartridge that is attached to the drum cartridge and has a developing roller 53, and is detachably attached to the device main body 2. In this case, the process cartridge 50 is attached to the device main body 2 by inserting the drum cartridge and the developer cartridge attached to the drum cartridge together into the device main body 2, and is detached from the device main body 2 by removing the drum cartridge and the developer cartridge attached to the drum cartridge together from the device main body 2.

[0056] The process cartridge 50 is an example of a cartridge and can include at least one of a photosensitive drum, a developing roller, and a toner container. The process cartridge 50 can be attached to and detached from the apparatus main body 2 when the front cover 21 is in the open position.

[0057] When the process cartridge 50 is attached to the apparatus main body 2, the photosensitive drum 54 is disposed in a position in which the axis X is aligned along the left-right direction. The photosensitive drum 54 has a metallic drum shaft 54a extending along the axis X. The photosensitive drum 54 rotates around the drum shaft 54a.

[0058] In this embodiment, the process cartridge 50 comprises a drum cartridge having a photosensitive drum 54, and a developing cartridge attached to the drum cartridge and having a developing roller 53, but it can also be configured to comprise a cartridge having the photosensitive drum 54 and the developing roller 53, and a toner box attached to the cartridge for containing toner.

[0059] Furthermore, the image forming apparatus can be configured so that a drum cartridge having a photosensitive drum 54 and a developer cartridge having a developer roller 53 are separately mounted in the apparatus main body 2. That is, the process cartridge 50 includes at least one of a photosensitive drum, a developer roller, and a toner container, and can be configured so as to be detachably mounted in the apparatus main body.

[0060] The exposure unit 56 is equipped with a laser diode, a polygon mirror, a lens, a reflecting mirror, etc., and exposes the surface of the photosensitive drum 54 by irradiating the photosensitive drum 54 with laser light based on image data input to the image forming apparatus 1.

[0061] Toner that becomes the developer is accommodated in the developer accommodating chamber 51. The toner accommodated in the developer accommodating chamber 51 is sent to the supply roller 52 while being stirred by a stirring member (not shown). The supply roller 52 further supplies the toner sent from the developer accommodating chamber 51 to the developing roller 53.

[0062] The developing roller 53 is disposed in close contact with the supply roller 52, and carries the toner supplied from the supply roller 52 and positively charged by a sliding contact member (not shown). A developing bias is applied to the developing roller 53 by a bias application means (not shown).

[0063] The photosensitive drum 54 is disposed adjacent to the developing roller 53. The surface of the photosensitive drum 54 is uniformly charged by a charger (not shown) and then exposed by the exposure unit 56. The exposed portion of the photosensitive drum 54 has a lower potential than other portions, and an electrostatic latent image based on the image data is formed on the photosensitive drum 54. Then, positively charged toner is supplied from the developing roller 53 to the surface of the photosensitive drum 54 on which the electrostatic latent image has been formed, thereby visualizing the electrostatic latent image into a toner image.

[0064] The transfer roller 55 is disposed opposite the photosensitive drum 54, and a transfer bias is applied to it by a bias application means (not shown). With the transfer bias applied to the surface of the transfer roller 55, the sheet S is conveyed while being sandwiched between the photosensitive drum 54 on which the toner image is formed and the transfer roller 55, whereby the toner image formed on the surface of the photosensitive drum 54 is transferred to the surface of the sheet S. The sheet S on which the toner image has been transferred is conveyed to the fixing unit 6.

[0065] The fixing device 6 includes a heating unit 61 and a pressure roller 62, and fixes the image transferred onto the sheet S by the process cartridge 50. The heating unit 61 is heated by supplying power from a power source (not shown). The heating unit 61 is an example of a heating section, and the pressure roller 62 is an example of a pressure section. The pressure roller 62 is disposed opposite the heating unit 61. One of the heating unit 61 and the pressure roller 62 is biased toward the other by a biasing mechanism (not shown), and the heating unit 61 and the pressure roller 62 are in close contact with each other.

[0066] When the sheet S onto which the toner image has been transferred is transported to the fixing device 6, the sheet S is conveyed while being sandwiched between a heating unit 61 and a pressure roller 62, whereby the sheet S is heated and the toner image is fixed onto the sheet S. In this manner, the fixing device 6 fixes the toner image transferred onto the sheet S being conveyed.

[0067] The paper discharge section 7 is located downstream of the image forming section 5 in the sheet transport direction, and discharges the sheet S on which an image has been formed by the image forming section 5 to the outside of the image forming apparatus 1. The paper discharge section 7 includes a pair of paper discharge rollers 71 and a paper discharge tray 72. The pair of paper discharge rollers 71 are configured to be able to discharge the sheet S, which has been transported from the fixing unit 6 along the transport path P, to the outside of the device body 2. The paper discharge tray 72 is formed on the top surface of the device body 2, and supports the sheet S discharged to the outside of the device body 2 by the pair of paper discharge rollers 71.

[0068] As shown in Fig. 2, the device body 2 includes a first body frame 24 and a second body frame 25 that are spaced apart from each other in the left-right direction. The first body frame 24 is located at the right end of the device body 2, and the second body frame 25 is located at the left end of the device body 2. The first body frame 24 extends in the front-rear and up-down directions and is disposed with its plate surface facing the left-right directions. The second body frame 25 extends in the front-rear and up-down directions and is disposed with its plate surface facing the left-right directions.

[0069] The process cartridge 50 and the fixing unit 6 are disposed between the first body frame 24 and the second body frame 25. The first body frame 24 is disposed to the right of the process cartridge 50 and the fixing unit 6, and the second body frame 25 is disposed to the left of the process cartridge 50 and the fixing unit 6. The process cartridge 50 is detachably supported by the first body frame 24 and the second body frame 25.

[0070] [Fuser] 3 and 4, the heating unit 61 of the fixing device 6 includes a heater 611, a holder 612, a stay 613, and a belt 614. The heater 611 is a flat plate-shaped heater extending in the left-right direction. The heater 611 has a first surface 611A and a second surface 611B opposite to the first surface 611A, and the first surface 611A is supported by the holder 612.

[0071] The holder 612 is made of, for example, a resin member, and has a guide surface 612a and a support wall 612b. The guide surface 612a contacts an inner circumferential surface 614a of the belt 614 to guide the belt 614. The support wall 612b has a support surface 612A that supports the heater 611. The support surface 612A of the support wall 612b abuts against a first surface 611A of the heater 611. The stay 613 is a member that supports the holder 612, and is formed by bending a plate material having greater rigidity than the holder 612, such as a steel plate, into a generally U-shaped cross section.

[0072] The belt 614 is an endless belt having heat resistance and flexibility, and includes a metal tube made of a metal such as stainless steel and a fluororesin layer covering the metal tube. The heater 611, the holder 612, and the stay 613 are disposed inside the belt 614. The belt 614 is configured to rotate around the heater 611, the holder 612, and the stay 613. An inner peripheral surface 614a of the belt 614 contacts the heater 611.

[0073] The pressure roller 62 has a metal shaft 62A and an elastic layer 62B that covers the shaft 62A. The pressure roller 62 is pressed against the heater 611 via a belt 614. The pressure roller 62 sandwiches the belt 614 between itself and the heater 611 to form a nip NP for heating and pressurizing the sheet S. In other words, the pressure roller 62 forms a nip NP with the pressure roller 62, and in the nip NP, the sheet S is heated and pressurized together with the heater 611.

[0074] The pressure roller 62 is configured to be rotationally driven by a driving force transmitted from a motor included in the image forming apparatus 1. The pressure roller 62 is rotationally driven to rotate the belt 614 by frictional force with the belt 614 or the sheet S sandwiched in the nip NP. As a result, the sheet S onto which the toner image has been transferred is transported between the pressure roller 62 and the heated belt 614, whereby the toner image is thermally fixed.

[0075] As shown in FIG. 1 and FIG. 5 to FIG. 7, the fixing unit 6 has a fixing frame 63 that covers the heating member 61 and the pressure roller 62, and a shutter 64 supported by the fixing frame 63. The fixing frame 63 holds the heating member 61 and the pressure roller 62. The fixing frame 63 covers the periphery of the heating member 61 and the pressure roller 62, and has a first opening 63a formed on the upstream side of the heating member 61 and the pressure roller 62 in the sheet conveying direction, and a second opening 63b formed on the downstream side of the heating member 61 and the pressure roller 62 in the sheet conveying direction. The fixing frame 63 covers the heating unit 61 from above.

[0076] The shutter 64 is located upstream of the first opening 63a in the fixing frame 63 in the sheet conveying direction, and has a rotation shaft 641 extending along the left-right direction, and a connecting shaft 642 protruding in a direction parallel to the rotation shaft 641. The rotation shaft 641 is rotatably supported by the fixing frame 63. The rotation shaft 641 is provided at both left and right ends of the shutter 64, and the connecting shaft 642 protrudes rightward from the right end of the shutter 64.

[0077] The shutter 64 is configured to be rotatable about a rotation shaft 641, and by rotating about the rotation shaft 641, the shutter 64 can move between a closed position (position shown in Figs. 5(a), 6(a), and 7(a)) where the first opening 63a is closed and an open position (position shown in Figs. 5(b), 6(b), and 7(b)) where the first opening 63a is opened. When the shutter 64 is in the closed position, the nip NP between the heating member 61 and the pressure roller 62 is covered by the shutter 64, and when the shutter 64 is in the open position, the nip NP between the heating member 61 and the pressure roller 62 is exposed to the outside of the fixing frame 63 through the first opening 63a.

[0078] Furthermore, the shutter 64 covers a part of the heating member 61 when in the closed position, and opens a part of the heating member 61 when in the open position. That is, the shutter 64 is displaceable between a closed position where the shutter 64 covers a part of the heating member 61 and an open position where the shutter 64 opens a part of the heating member 61.

[0079] As shown in FIGS. 5, 7, and 8, the shutter 64 has a contact end 64a located at the upper end when the shutter 64 is in the closed position. The fixing frame 63 has a contact surface 631 against which the shutter 64 in the open position contacts. The contact surface 631 faces the upstream side in the sheet conveying direction, and the contact end 64a of the shutter 64 contacts the contact surface 631 when the shutter 64 is in the open position. When the contact end 64a of the shutter 64 contacts the contact surface 631, the shutter 64 is restricted from moving further in the opening direction. In other words, the contact surface 631 is a restricting surface on the open position side that contacts the shutter 64 in the open position to restrict the position of the shutter 64.

[0080] 5, 6 and 8, the shutter 64 has a contact portion 64b that contacts the fixing frame 63 when the shutter 64 is in the closed position. The contact portion 64b is located at the right end portion of the shutter 64. The fixing frame 63 has a contact surface 632 that contacts the shutter 64 in the closed position.

[0081] The abutment surface 632 faces the upstream side in the sheet conveying direction, and is abutted by the abutment portion 64b of the shutter 64 when the shutter 64 is in the closed position. The abutment portion 64b of the shutter 64 abuts against the abutment surface 632, thereby restricting the shutter 64 from moving further in the closing direction. In other words, the abutment surface 632 is a restricting surface on the closed position side that abuts against the shutter 64 in the closed position and restricts the position of the shutter 64.

[0082] In this embodiment, the fixing device 6 includes a heating unit 61 having a heater 611 and a belt 614, and a pressure roller 62, but the fixing device 6 can also include a heating roller with a built-in heater and a pressure roller pressed against the heating roller. The fixing device 6 can also include a heating roller with a built-in heater and a pressure belt pressed against the heating roller by an elastic member.

[0083] [Drum shaft] 9 and 10, the drum shaft 54a of the photosensitive drum 54 protrudes rightward along the axis X from the right end of the process cartridge 50. In other words, the drum shaft 54a protrudes toward the first main body frame 24 along the axis X.

[0084] [First main body frame] 11 and 12, the first main body frame 24 has a front frame 24A located in the front and a rear frame 24B located behind the front frame 24A. The front frame 24A and the rear frame 24B are integrally formed continuously in the front-rear direction. The front frame 24A of the first main body frame 24 is an example of a frame.

[0085] The front frame 24A of the first main body frame 24 has a cartridge rail 241 and a contact piece rail 242. The cartridge rail 241 is formed in a groove shape that is open on the left side. The cartridge rail 241 extends in the front-rear direction and is inclined downward as it goes from the front to the rear.

[0086] The drum shaft 54a of the photosensitive drum 54 can enter the cartridge rail 241, and the cartridge rail 241 guides the drum shaft 54a when the process cartridge 50 is mounted in the apparatus main body 2 and when the process cartridge 50 is removed from the apparatus main body 2. The drum shaft 54a, guided by the cartridge rail 241, enters the cartridge rail 241 from the left side. The process cartridge 50 is mounted in the apparatus main body 2 from the front to the rear, and is removed from the apparatus main body 2 from the rear to the front.

[0087] In this way, the cartridge rail 241 of the front frame 24A guides the drum shaft 54a when the process cartridge 50 is attached to and detached from the apparatus main body 2. The cartridge rail 241 is an example of a first guide groove that guides the drum shaft.

[0088] The contact piece rail 242 is formed in a groove shape that is open on the right side. The contact piece rail 242 extends in the front-rear direction and is inclined downward as it goes from the front to the rear. The contact piece rail 242 is located to the right of the cartridge rail 241 in the left-right direction. In other words, the contact piece rail 242 is located outside the cartridge rail 241 in the left-right direction.

[0089] The cartridge rail 241 has a front portion 241a located in the front, a rear portion 241c located in the rear, and a middle portion 241b located between the front portion 241a and the rear portion 241c. The contact piece rail 242 has a front portion 242a located in the front, a rear portion 242c located in the rear, and a middle portion 242b located between the front portion 242a and the rear portion 242c.

[0090] The middle portion 241b of the cartridge rail 241 and the middle portion 242b of the abutment piece rail 242 overlap and communicate with each other. The middle portions 241b and 242b form a through hole 24C that passes through the front frame 24A in the left-right direction.

[0091] That is, a middle portion 241b that is a part of the cartridge rail 241 and a middle portion 242b that is a part of the abutment piece rail 242 overlap with each other, and the overlapping portion between the cartridge rail 241 and the abutment piece rail 242 is the through hole 24C. Since the cartridge rail 241 and the abutment piece rail 242 partially overlap in this manner, it is possible to use the same material for forming the cartridge rail 241 and the abutment piece rail 242.

[0092] The drum shaft 54a of the cartridge rail 241 enters the through hole 24C when the process cartridge 50 is mounted to the apparatus main body 2 and when the process cartridge 50 is removed from the apparatus main body 2.

[0093] A front portion 242 a of the contact piece rail 242 is positioned higher than a front portion 241 a of the cartridge rail 241 , and a rear portion 242 c of the contact piece rail 242 is positioned higher than a rear portion 241 c of the cartridge rail 241 .

[0094] [link] As shown in Figures 6, 13 and 14, the main body 2 of the apparatus is provided with a link 8 which is capable of coming into contact with the process cartridge 50 and which moves the shutter 64 to an open position and a closed position. The link 8 is connected to the shutter 64. When the process cartridge 50 is attached to the main body 2 of the apparatus, the link 8 comes into contact with the process cartridge 50 to move the shutter 64 from the closed position to the open position, and when the process cartridge 50 is detached from the main body 2 of the apparatus, the link 8 comes into contact with the process cartridge 50 to move the shutter 64 from the open position to the closed position. In this way, the link 8 moves the shutter 64 to the closed position and the open position in response to the operation of the process cartridge 50.

[0095] In other words, the link 8 is configured so that the shutter 64 opens and closes in response to the attachment and detachment of the process cartridge 50 to and from the apparatus main body 2. Specifically, when the process cartridge 50 is attached to the image forming apparatus 1, the shutter 64 moves to an open position, and when the process cartridge 50 is removed from the image forming apparatus 1, the shutter 64 moves to a closed position. The link 8 is located on the opposite side of the process cartridge 50 attached to the apparatus main body 2 with respect to the front frame 24A of the first main body frame 24 in the left-right direction.

[0096] The link 8 is movable to a first position before the process cartridge 50 is attached to the apparatus main body 2. When the link 8 is in the first position, the shutter 64 is moved to a closed position. The link 8 is movable to a second position after the process cartridge 50 is attached to the apparatus main body 2. When the link 8 is in the second position, the shutter 64 is moved to an open position.

[0097] That is, the link 8 is displaceable between a first position for moving the shutter 64 to the closed position and a second position for moving the shutter 64 to the open position. The link 8 displaces in a first direction from the first position to the second position when the shutter 64 is moved from the closed position to the open position. Also, the link 8 displaces in a second direction from the second position to the first position when the shutter 64 is moved from the open position to the closed position.

[0098] The link 8 has an abutment piece 80, a first rotating link 81, a linear link 82, a second rotating link 83, a third rotating link 84, a shutter link 85, and a coil spring 86. The linear link 82 is an example of a first link, and the first rotating link 81 is an example of a second link.

[0099] The contact piece 80 moves in contact with the drum shaft 54a of the photosensitive drum 54. The contact piece 80 is slidably fitted into a contact piece rail 242, which guides the contact piece 80 that moves in contact with the drum shaft 54a. The contact piece rail 242 is an example of a second guide groove that guides the contact piece.

[0100] 15, the abutment piece 80 has a main body 801, a connecting portion 802, a first boss 803, and a second boss 804. The main body 801 is formed of a plate-like member whose plate surface faces in the left-right direction. The connecting portion 802 is a protrusion that protrudes rightward from the right surface of the main body 801.

[0101] The first boss 803 and the second boss 804 are protrusions that protrude leftward from the left surface of the main body portion 801. The first boss 803 and the second boss 804 enter the contact piece rail 242 of the first main body frame 24 from the right side, and are guided by the contact piece rail 242.

[0102] In a state where the first boss 803 and the second boss 804 have entered the contact piece rail 242, the second boss 804 is located upstream of the first boss 803 in the mounting direction of the process cartridge 50 into the apparatus body 2. Note that the mounting direction refers to the direction in which the process cartridge 50 inserted into the apparatus body 2 moves toward the mounting position when the process cartridge 50 is mounted into the apparatus body 2.

[0103] The contact piece 80 is located on the opposite side of the process cartridge 50 mounted in the apparatus main body 2 with respect to the front frame 24A of the first main body frame 24. The first boss 803 and the second boss 804 are located at positions not protruding toward the process cartridge 50 side beyond the front frame 24A of the first main body frame 24 when inserted into the contact piece rail 242.

[0104] The first boss 803 abuts against the drum shaft 54a when the process cartridge 50 is attached to the apparatus body 2, and the second boss 804 abuts against the drum shaft 54a when the process cartridge 50 is removed from the apparatus body 2. In other words, the first boss 803 abuts against the drum shaft 54a of the process cartridge 50 attached to the apparatus body 2, and the second boss 804 abuts against the drum shaft 54a of the process cartridge 50 removed from the apparatus body 2.

[0105] In this case, when the first boss 803 is located at the middle portion 242b (through hole 24C) of the contact piece rail 242, it abuts against the drum shaft 54a of the process cartridge 50 mounted in the apparatus main body 2 through the through hole 24C. Also, when the second boss 804 is located at the middle portion 242b (through hole 24C) of the contact piece rail 242, it abuts against the drum shaft 54a of the process cartridge 50 detached from the apparatus main body 2 through the through hole 24C.

[0106] The drum shaft 54a, which abuts against the first boss 803 and the second boss 804 through the through hole 24C, may abut against the first boss 803 and the second boss 804 inside the through hole 24C, or may abut against the first boss 803 and the second boss 804 at a position extending to the right of the through hole 24C in the left-right direction.

[0107] In this embodiment, the abutment piece 80 is configured to move in contact with the drum shaft 54a, but it is also possible to form a cartridge protrusion on the process cartridge 50 that protrudes toward the first main body frame 24 side separately from the drum shaft 54a, and to configure the abutment piece 80 to move in contact with this cartridge protrusion.

[0108] The first rotating link 81 is a substantially linear member that is rotatably connected to the abutment piece 80. The first rotating link 81 is located to the right of the front frame 24A of the first main body frame 24 in the left-right direction. The first rotating link 81 has a fitting portion 811 that is located at the front end and into which the connecting portion 802 of the abutment piece 80 is rotatably fitted, and a boss 812 that is located at the rear end and protrudes to the left. The first rotating link 81 is disposed in an inclined position in which the fitting portion 811 is located above and forward of the boss 812. The first rotating link 81 is connected to the abutment piece 80 by fitting the connecting portion 802 into the fitting portion 811, and rotates along with the movement of the abutment piece 80.

[0109] The linear link 82 is a substantially linear member that is rotatably connected to the first rotating link 81 and extends in the front-rear direction. The linear link 82 is located to the right of the front frame 24A of the first main body frame 24 in the left-right direction. The linear link 82 has a fitting portion 821 located at the front end portion and into which the boss 812 of the first rotating link 81 is rotatably fitted, and a connecting hole 822 located at the rear end portion. The linear link 82 is connected to the first rotating link 81 by fitting the boss 812 into the fitting portion 821, and moves linearly in the front-rear direction along with the rotation of the first rotating link 81.

[0110] The linear link 82 moves from front to rear when the link 8 moves the shutter 64 from the closed position to the open position, and moves from rear to front when the link 8 moves the shutter 64 from the open position to the closed position. The position of the linear link 82 at which the shutter 64 is moved to the closed position is the first position, and the position of the linear link 82 at which the shutter 64 is moved to the open position is the second position. That is, in this embodiment, the first direction of the linear link 82 from the first position to the second position is the rearward direction, and the second direction of the linear link 82 from the second position to the first position is the forward direction.

[0111] The second rotating link 83 is connected to the linear link 82 and supported by the first main body frame 24. The second rotating link 83 has a support part 831 that is rotatably supported by the first main body frame 24, a first arm 832 that extends substantially downward from the support part 831, and a second arm 833 that extends substantially upward from the support part 831. An engagement pin 832a that protrudes leftward is formed at the tip of the first arm 832, and a connecting hole 833a is formed at the tip of the second arm 833.

[0112] The engagement pin 832a of the first arm 832 enters the connecting hole 822 of the linear link 82 from the right, and engages with the connecting hole 822 as the linear link 82 moves in the front-rear direction. The second rotating link 83 is connected to the linear link 82 by the engagement of the engagement pin 832a with the connecting hole 822, and rotates about the support part 831 as the linear link 82 moves.

[0113] The third rotating link 84 is connected to the second rotating link 83, and is rotatably supported by the support shaft 65 of the fixing unit 6. The third rotating link 84 has a support portion 841 rotatably supported by the support shaft 65, an engagement pin 842 protruding rightward from the support portion 841, an operation cam 843 formed in a different phase from the engagement pin 842 in the circumferential direction of the support portion 841, and a connecting hole 844 formed in the operation cam 843. The connecting hole 844 passes through the operation cam 843 in the left-right direction. The third rotating link 84 is an example of a link cam.

[0114] The engagement pin 842 of the third rotating link 84 enters the connecting hole 833a of the second rotating link 83 from the left, and engages with the connecting hole 833a as the second rotating link 83 rotates. The third rotating link 84 is connected to the second rotating link 83 by the engagement of the engagement pin 842 with the connecting hole 833a, and rotates about the support shaft 65 as the second rotating link 83 rotates.

[0115] 5 and 6, the shutter link 85 is connected to the third rotating link 84 and is rotatably supported on the support shaft 65 of the fixing unit 6. The shutter link 85 moves along with the movement of the third rotating link 84 to move the shutter 64 of the fixing unit 6 between a closed position and an open position. The shutter link 85 is located at the right end of the fixing unit 6 and has a support portion 851, an arm portion 852, an engagement portion 853, and an engagement pin 854.

[0116] The support portion 851 is rotatably supported by a support shaft 65 that protrudes rightward from the right end of the fixing frame 63. The arm portion 852 is an arm member that extends forward from the support portion 851. The engagement portion 853 is located at the front end of the arm portion 852, and has an oval engagement hole 853a that is long in the front-rear direction. A connecting shaft 642 that protrudes rightward from the right end of the shutter 64 engages with the engagement hole 853a. The engagement hole 853a engages with the connecting shaft 642, connecting the shutter link 85 to the shutter 64.

[0117] The shutter link 85 can rotate around the support portion 851 in a direction in which the engaging portion 853 moves up and down, and when the shutter link 85 rotates and the engaging portion 853 moves downward, the shutter 64 moves to the closed position (see Figs. 5(a) and 6(a)), and when the shutter link 85 rotates and the engaging portion 853 moves upward, the shutter 64 moves to the open position (see Figs. 5(b) and 6(b)). In other words, the shutter link 85 moves the shutter 64 to the closed position by rotating downward, and moves the shutter 64 to the open position by rotating upward.

[0118] The engagement pin 854 protrudes rightward from the end of the arm portion 852 on the support portion 851 side. The engagement pin 854 of the shutter link 85 enters the connection hole 844 of the third rotating link 84 from the left.

[0119] The coil spring 86 is supported by a support portion 841 of the third rotating link 84. The coil spring 86 is an example of a link spring. The coil spring 86 moves along with the movement of the third rotating link 84. The coil spring 86 has an arm portion 861. The arm portion 861 extends from the inner diameter side of the connecting hole 844 toward the outer diameter side, and enters the connecting hole 844.

[0120] The arm 861 is located above the engagement pin 854 in the connecting hole 844. The coil spring 86 is rotatable along with the rotation of the third rotating link 84. The edge of the lower end of the connecting hole 844 in the operation cam 843 of the third rotating link 84 forms an engagement surface 844a. The engagement surface 844a is located below the engagement pin 854. The connecting hole 844 has an inner circumferential surface 844b on the edge opposite to the edge on the side where the engagement surface 844a is formed in the circumferential direction. The inner circumferential surface 844b is located above the arm 861, and a gap exists between the inner circumferential surface 844b and the arm 861.

[0121] The engagement surface 844a of the connecting hole 844 engages with the engagement pin 854 as the third rotating link 84 rotates in the side in which the operation cam 843 moves upward. The arm portion 861 of the coil spring 86 engages with the engagement pin 854 as the third rotating link 84 rotates in the side in which the operation cam 843 moves downward.

[0122] The shutter link 85 is connected to the third rotating link 84 by the engagement pin 854 engaging with the arm portion 861 or the engagement surface 843a, and moves in accordance with the rotation of the third rotating link 84, moving the shutter 64 between the closed position and the open position.

[0123] Specifically, along with the rotation of the third rotating link 84 toward the side where the operation cam 843 moves downward, the shutter link 85 is pressed by the coil spring 86 to rotate downward, and the shutter 64 moves to the closed position. The position of the third rotating link 84 when the shutter 64 moves to the closed position due to the rotation of the third rotating link 84 is the first position.

[0124] In addition, along with the rotation of the third rotating link 84 toward the side where the operation cam 843 moves upward, the shutter link 85 is pressed by the engagement surface 844a of the connecting hole 844 and rotates upward, and the shutter 64 moves to the open position. The position of the third rotating link 84 when the shutter 64 moves to the open position by the rotation of the third rotating link 84 is the second position.

[0125] In the image forming apparatus 1, when the process cartridge 50 is attached to or detached from the device main body 2, the abutment piece 80 of the link 8 abuts against the drum shaft 54a and moves along the abutment piece rail 242, whereby a driving force is transmitted to the shutter 64 via the link 8, and the shutter 64 moves between the closed position and the open position.

[0126] In this embodiment, the link 8 has a configuration including the abutment piece 80, the first rotating link 81, the linear link 82, the second rotating link 83, the third rotating link 84, the shutter link 85, and the coil spring 86, but is not limited to this and may be configured as one link that is connected to the shutter 64 and abuts against the process cartridge 50 to open and close the shutter 64. Furthermore, the movement of the link 8 is not limited to rotation or sliding, and it may be any movement that opens and closes the shutter 64 in an appropriate manner in response to the insertion and removal of the process cartridge 50.

[0127] [Using member] 13, the device body 2 includes a biasing member 9. In the process in which the link 8 moves the shutter 64 from the closed position to the open position, before the shutter 64 moves to the open position, the biasing member 9 presses the link 8 in a direction in which the shutter 64 moves to the open position. When the shutter 64 is in the open position, the biasing member 9 biases the link 8 in a first direction in which the link 8 moves from the first position to the second position.

[0128] Furthermore, in the process in which the link 8 moves the shutter 64 from the open position to the closed position, before the shutter 64 moves to the closed position, the biasing member 9 presses the link 8 in a direction in which the shutter 64 moves to the closed position. When the shutter 64 is in the closed position, the biasing member 9 biases the link 8 in a second direction in which the link 8 moves from the second position to the first position.

[0129] Furthermore, the biasing member 9 restricts the movement of the link 8 that has moved the shutter 64 to the open position or the closed position by pressing the link 8. That is, when the shutter 64 is in the closed position, the biasing member 9 biases the shutter 64 so as to be held in the closed position, and when the shutter 64 is in the open position, the biasing member 9 biases the shutter 64 so as to be held in the open position.

[0130] In this way, when the shutter 64 is in the closed position, the biasing member 9 biases the shutter 64 to be held in the closed position, and when the shutter 64 is in the open position, the biasing member 9 biases the shutter 64 to be held in the open position, so that the single biasing member 9 can stably hold the shutter 64 in the open position in an open state, and can stably hold the shutter 64 in the closed position in a closed state.

[0131] The biasing member 9 has a pressing spring 92 and a pressing arm 91 that is pressed by the pressing spring 92 and comes into contact with the upper surface 82A of the linear link 82. The pressing spring 92 is an example of a spring that biases the link, and the pressing arm 91 is an example of a pressing portion that is connected to the spring and presses the link. The pressing spring 92 presses the tip of the pressing arm 91 toward the upper surface 82A of the linear link 82. The upper surface 82A of the linear link 82 is an example of a pressed surface that is pressed by the pressing arm. The biasing member 9 is capable of stably pressing the linear link 82 by the pressing arm 91 that is connected to the pressing spring 92.

[0132] The pressing arm 91 has a support portion 911 located at the base end of the pressing arm 91 and rotatably supported on the first main body frame 24, a contact portion 912 located at the tip of the pressing arm 91 and contacting the upper surface 82A of the linear link 82, and a fitting portion 913 into which the pressing spring 92 fits. The pressing arm 91 extends in the front-rear direction, with the support portion 911 located at the front end and the contact portion 912 located at the rear end. The fitting portion 913 is located above the contact portion 912. The contact portion 912 is rotatable in the up-down direction around the support portion 911.

[0133] The support portion 911 is a rotation center of the pressing arm 91. The base end of the pressing arm 91 is an example of one end of a pressing portion of a biasing member, and the tip of the pressing arm 91 is an example of the other end of a pressing portion of a biasing member. The pressing arm 91 has an abutment portion 912 at its tip, which enables the pressing arm 91 to smoothly press the linear link 82.

[0134] The pressing spring 92 is supported by the first main body frame 24, and its lower end is fitted into a fitting portion 913 of the pressing arm 91. The pressing spring 92 biases the abutting portion 912 of the pressing arm 91 downward toward the upper surface 82A of the linear motion link 82, and the abutting portion 912 is pressed against the upper surface 82A from above.

[0135] The upper surface 82A of the linear motion link 82 has a link protrusion 823 between the fitting portion 821 and the connecting hole 822, protruding upward toward the biasing member 9. The link protrusion 823 is formed in a mountain shape having a first pressed surface 823a, a second pressed surface 823b, and a third pressed surface 823c.

[0136] The third pressed surface 823c is an example of a first portion of the link, and the second pressed surface 823b is an example of a second portion of the link. The third pressed surface 823c is a first inclined surface inclined with respect to the moving direction of the linear link 82, and the second pressed surface 823b is a second inclined surface inclined with respect to the moving direction of the linear link 82. The inclination direction of the third pressed surface 823c with respect to the moving direction of the linear link 82 is different from the inclination direction of the second pressed surface 823b with respect to the moving direction of the linear link 82.

[0137] The first pressed surface 823a is located at the apex of the mountain shape and extends horizontally. The second pressed surface 823b is located in front of the first pressed surface 823a and is formed as an inclined surface that rises toward the rear. In other words, the second pressed surface 823b is inclined from the bottom to the top along the rear direction. In this way, the second pressed surface 823b, which is the second inclined surface, has an inclined shape that rises along the moving direction of the linear link 82 from the first position to the second position. The rear end of the second pressed surface 823b is connected to the front end of the first pressed surface 823a.

[0138] The third pressed surface 823c is located behind the first pressed surface 823a, and is formed as an inclined surface that descends toward the rear. That is, the third pressed surface 823c is inclined from top to bottom along the rear direction. In this way, the third pressed surface 823c, which is the first inclined surface, has an inclined shape that ascends along the moving direction of the linear link 82 from the second position to the first position. The front end of the third pressed surface 823c is connected to the rear end of the first pressed surface 823a. The third pressed surface 823c is located on the opposite side to the second pressed surface 823b across the first pressed surface 823a in the front-rear direction.

[0139] By moving in the front-rear direction, the linear link 82 can be positioned at a position where the abutting portion 912 of the pressing arm 91 presses the first pressed surface 823a, a position where the abutting portion 912 of the pressing arm 91 presses the second pressed surface 823b, and a position where the abutting portion 912 of the pressing arm 91 presses the third pressed surface 823c. The third pressed surface 823c abuts against the pressing arm 91 when the linear link 82 is in the first position, and the second pressed surface 823b abuts against the pressing arm 91 when the linear link 82 is in the second position.

[0140] Since the first pressed surface 823a is a surface extending horizontally, when the pressing arm 91 presses the first pressed surface 823a from above, the pressing force of the pressing arm 91 does not act in either the backward direction in which the linear link 82 moves toward the second position, or the forward direction in which the linear link 82 moves toward the first position.

[0141] Since the second pressed surface 823b is a surface that inclines from the bottom to the top along the rearward direction, when the pressing arm 91 presses the second pressed surface 823b from above, the pressing force of the pressing arm 91 acts in the rearward direction in which the linear link 82 moves toward the second position. When the pressing arm 91 abuts against the second pressed surface 823b, the biasing direction of the pressing spring 92, which is downward, is converted by the second pressed surface 823b into a first direction in which the linear link 82 moves from the first position to the second position. Also, when the pressing arm 91 presses the second pressed surface 823b from above, the abutting portion 912 of the pressing arm 91 and the second pressed surface 823b are engaged with each other, and the forward movement of the linear link 82 is restricted.

[0142] Since the third pressed surface 823c is a surface that inclines from above to below along the rearward direction, when the pressing arm 91 presses the third pressed surface 823c from above, the pressing force of the pressing arm 91 acts in a forward direction in which the linear link 82 moves toward the first position. When the pressing arm 91 is in contact with the third pressed surface 823c, the downward biasing direction of the pressing spring 92 is converted by the third pressed surface 823c into a second direction in which the linear link 82 moves from the second position to the first position. Also, when the pressing arm 91 is pressing the third pressed surface 823c from above, the abutting portion 912 of the pressing arm 91 and the third pressed surface 823c are engaged with each other, and the rearward movement of the linear link 82 is restricted.

[0143] In this way, since the linear link 82 has the second pressed surface 823b and the third pressed surface 823c, the biasing force of a single pressing spring 92 can stably hold the shutter 64 in the closed position in a closed state, and can also stably hold the shutter 64 in the open position in an open state.

[0144] Furthermore, since the second pressed surface 823b and the third pressed surface 823c are inclined surfaces inclined with respect to the movement direction of the linear link 82, it is possible to easily form the second pressed surface 823b and the third pressed surface 823c on the linear link 82.

[0145] In addition, the second pressed surface 823b has an inclined shape that rises along the movement direction of the linear link 82 from the first position to the second position, and the third pressed surface 823c has an inclined shape that rises along the movement direction of the linear link 82 from the second position to the first position, so that the biasing direction of the pressing spring 92 can be efficiently converted between the direction in which the linear link 82 moves from the first position to the second position and the direction in which the linear link 82 moves from the second position to the first position.

[0146] In addition, as the linear link 82 is displaced in the front-rear direction, the pressing arm 91 of the biasing member 9 switches between a state in which it presses the second pressed surface 823b and a state in which it presses the third pressed surface 823c, and thus the link 8 acts as a switching mechanism that switches the biasing direction of the biasing member 9 between a direction in which it biases the shutter 64 to be held in the closed position and a direction in which it biases the shutter 64 to be held in the open position. As a result, the link 8 and the biasing member 9, which are the switching mechanism, can stably hold the shutter 64 in the open position in the open state, and can stably hold the shutter 64 in the closed position in the closed state.

[0147] In addition, by using link 8 as a switching mechanism that switches the biasing direction of biasing member 9 and having biasing member 9 bias link 8, it becomes possible to use a common member to open and close shutter 64 and to hold shutter 64 in the closed and open positions.

[0148] Link Behavior Next, the operation of the link 8 will be described.

[0149] (Operation when installing a process cartridge) First, the operation of the link 8 when the process cartridge 50 is mounted in the apparatus main body 2 will be described.

[0150] As shown in Figures 13 and 14, when the process cartridge 50 is in a state after being removed from the apparatus main body 2 and before being attached to the apparatus main body 2, and when the leading end 50A of the process cartridge 50 in the insertion direction is in the attachment start position inserted into the apparatus main body 2 (the position shown in Figure 14), the drum shaft 54a is spaced forward from the abutment piece 80, and the abutment piece 80 is located across the front part 242a and the middle part 241b of the abutment piece rail 242.

[0151] Specifically, the abutment piece 80 is fitted to the abutment piece rail 242 with the first boss 803 located in the middle portion 242b (through hole 24C) of the abutment piece rail 242 and the second boss 804 located in the front portion 242a of the abutment piece rail 242. The insertion direction of the process cartridge 50 is the same as the mounting direction.

[0152] 14, the shutter 64 is moved to the closed position by the link 8 as shown in Fig. 6(a). As a result, when the process cartridge 50 is in a state where it is detached from the apparatus main body 2, even if the user inserts his / her hand into the apparatus main body 2 through the opening 2A, the shutter 64 can prevent the user's hand from touching the heating unit 61 of the fixing device 6.

[0153] 14, as shown in Fig. 13, the abutment portion 912 of the pressing arm 91 abuts against the third pressed surface 823c of the linear link 82, restricting the backward movement of the linear link 82. As a result, the linear link 82 is fixed by the biasing member 9 in a state in which the shutter 64 is moved to the closed position by the link 8, and the shutter 64 does not move inadvertently from the closed position to the open position, so that the closed position of the shutter 64 can be stably maintained.

[0154] Furthermore, the abutment piece rail 242 of the front frame 24A that guides the abutment piece 80 is located outside the cartridge rail 241 in the left-right direction, and the first boss 803 and the second boss 804 of the abutment piece 80 are located so as not to protrude further toward the process cartridge 50 than the front frame 24A. Therefore, when the process cartridge 50 is detached from the apparatus main body 2, it is possible to prevent the user from coming into contact with the abutment piece 80, and it is possible to prevent the link 8 from moving and the shutter 64 from opening inadvertently.

[0155] When the process cartridge 50, which is in the installation start position, is further inserted toward the installation position, the drum shaft 54a enters the front portion 241a of the cartridge rail 241 and moves inside the cartridge rail 241. As shown in FIG. 16, when the drum shaft 54a moving inside the cartridge rail 241 enters the middle portion 241b (through hole 24C), the drum shaft 54a comes into contact with the first boss 803 of the abutment piece 80.

[0156] As shown in FIGS. 17 to 19, the contact piece 80 that comes into contact with the drum shaft 54a moving within the middle portion 241b (through hole 24C) of the cartridge rail 241 is pressed by the drum shaft 54a and moves downstream in the mounting direction of the process cartridge 50.

[0157] The first boss 803 of the contact piece 80, which moves in contact with the drum shaft 54a moving in the middle portion 241b (through hole 24C), has a rear part located at the rear portion 242c of the contact piece rail 242, and the other part located at the middle portion 242b (through hole 24C) of the contact piece rail 242. In addition, the second boss 804 is located at the middle portion 242b (through hole 24C) of the contact piece rail 242.

[0158] When the abutment piece 80 moves, the first rotating link 81 connected to the abutment piece 80 moves rearward while rotating in a direction in which the inclination angle with respect to the horizontal direction becomes smaller. When the first rotating link 81 rotates and moves, the linear link 82 connected to the first rotating link 81 moves rearward linearly.

[0159] When the linear link 82 moves rearward, the connecting hole 822 of the linear link 82 engages with the engaging pin 832a of the second rotating link 83, and the second rotating link 83 rotates in a direction in which the engaging pin 832a moves rearward. When the second rotating link 83 rotates, the connecting hole 833a of the second rotating link 83 engages with the engaging pin 842 of the third rotating link 84, and the third rotating link 84 rotates in a direction in which the engaging pin 842 moves forward.

[0160] In this case, as the linear link 82 moves backward, the abutment portion 912 of the pressing arm 91 of the urging member 9 moves up the third pressed surface 823c of the linear link 82 against the pressing force of the pressing spring 92, and then rides from the third pressed surface 823c onto the first pressed surface 823a. That is, when the process cartridge 50 is mounted in the apparatus main body 2, the pressing arm 91 abuts against the third pressed surface 823c and then the first pressed surface 823a. In a state in which the pressing arm 91 abuts against the first pressed surface 823a, which is a surface extending in the horizontal direction, the restriction by the pressing member 9 of the shutter 64 moving from the closed position to the open position is released.

[0161] In this way, when the process cartridge 50 is attached to the apparatus main body 2, the linear link 82 moves backward in the first direction against the pressing force from the pressing arm 91, thereby making it possible to switch the shutter 64 from a state in which it is held in the closed position to a state in which it can be moved to the open position.

[0162] 20 and 21, when the process cartridge 50 is further inserted from the position shown in Fig. 18 toward the mounting position, the abutment piece 80 is moved further downstream in the mounting direction by the drum shaft 54a moving within the middle portion 241b (through hole 24C) of the cartridge rail 241. In Fig. 21, the first boss 803 of the abutment piece 80 is located at the rear portion 242c of the abutment piece rail 242, and the second boss 804 is located at the middle portion 242b (through hole 24C) of the abutment piece rail 242.

[0163] As shown in FIG. 22, the drum shaft 54a moves the abutment piece 80 until the first boss 803 is positioned at the rear 242c of the abutment piece rail 242, and then moves from the middle 241b to the rear 241c of the cartridge rail 241, and the abutment piece 80 and the drum shaft 54a become separated.

[0164] When the abutment piece 80 moves, the first rotating link 81 moves rearward while rotating in a direction in which the inclination angle with respect to the horizontal direction becomes smaller. When the first rotating link 81 rotates and moves, the linear motion link 82 moves further rearward in a straight line. When the linear motion link 82 moves, the second rotating link 83 rotates further in the direction in which the engagement pin 832a moves rearward. When the second rotating link 83 rotates, the third rotating link 84 rotates further in the direction in which the engagement pin 842 moves forward.

[0165] When the third rotating link 84 rotates, an engagement surface 844a of the connecting hole 844 in the operation cam 843 engages with an engagement pin 854 of the shutter link 85 from below. When the engagement surface 844a of the connecting hole 844 engages with the engagement pin 854, the shutter link 85 rotates in a direction in which the engagement portion 853 moves upward, and the shutter 64 moves from the closed position to the open position.

[0166] In this case, the movement of the abutment piece 80 by the drum shaft 54a is transmitted to the linear link 82 via the first pivot link 81, so that even if the distance between the mounting position of the process cartridge 50 in the device main body 2 and the shutter 64 is large, it is possible to efficiently transmit driving force from the abutment piece 80 to the shutter 64.

[0167] When the drum shaft 54a moves the abutment piece 80 until the first boss 803 is positioned at the rear 242c of the abutment piece rail 242, the linear link 82 moves rearward, and the abutment portion 912 of the pressing arm 91 in the biasing member 9 transfers from the first pressed surface 823a to the second pressed surface 823b of the linear link 82 due to the pressing force of the pressing spring 92.

[0168] When the abutment piece 80 is moved by the drum shaft 54a until the first boss 803 is positioned at the rear 242c of the abutment piece rail 242, the abutment position of the abutment portion 912 of the pressing arm 91 against the second pressed surface 823b varies depending on the dimensional tolerances of each component that constitutes the link 8 and the tolerances of the connecting positions of each component, etc.

[0169] In this case, the positional relationship between the pressing arm 91 and the link 8 is set so that when the drum shaft 54a moves the abutting piece 80 until the first boss 803 is positioned at the rear part 242c of the abutting piece rail 242, the abutting portion 912 of the pressing arm 91 always abuts against the second pressed surface 823b. Furthermore, even if the abutting portion 912 of the pressing arm 91 abuts against the lowermost side of the second pressed surface 823b within the tolerance range of each member constituting the link 8, the abutting portion 912 is set not to come into contact with the upper surface 82A located forward of the second pressed surface 823b.

[0170] After the abutment piece 80 moves until the first boss 803 is positioned at the rear part 242c of the abutment piece rail 242 and the abutment portion 912 abuts against the second pressed surface 823b, the first boss 803 and the drum shaft 54a are separated from each other, so the drum shaft 54a does not move the abutment piece 80. However, as shown in Fig. 23, because the abutment portion 912 of the pressing arm 91 abuts against the second pressed surface 823b, a pressing force is applied from the pressing arm 91 to the linear link 82 in a direction toward the second position, and the linear link 82 moves backward.

[0171] As shown in FIG. 6(b), when the linear link 82 moves rearward due to the pressing force from the pressing arm 91, the shutter link 85 rotates in a direction in which the engaging portion 853 moves upward, and the shutter 64 moves to the open position.

[0172] In this case, even if the linear link 82 moves backward by the pressing force from the pressing arm 91 until the shutter 64 moves to the open position, the abutting portion 912 of the pressing arm 91 is set not to come into contact with the upper surface 82A located forward of the second pressed surface 823b (see FIG. 23). This makes it possible to hold the shutter 64 in the open position by the pressing force from the pressing arm 91.

[0173] Furthermore, as shown in FIG. 24, when the linear link 82 moves rearward due to the pressing force from the pressing arm 91, the abutment piece 80 is pulled rearward by the first pivot link 81, and the first boss 803 of the abutment piece 80 moves rearward from the position shown in FIG. 22 along the rear portion 241c of the abutment piece rail 242.

[0174] When the shutter 64 moves to the open position, the contact end 64a comes into contact with the contact surface 631 of the fixing frame 63, restricting further movement and also stopping the movement of the link 8. Since the shutter 64 is restricted from moving further by coming into contact with the contact surface 631, it is possible to hold the shutter 64 in the open position. Furthermore, since the movement of the link 8 is also stopped, the movement range of the link 8 can be kept small.

[0175] Furthermore, in a state where the pressing arm 91 is in contact with the second pressed surface 823b, the contact portion 912 of the pressing arm 91 and the second pressed surface 823b are engaged to restrict the forward movement of the linear motion link 82. As a result, when the shutter 64 is moved to the open position, the position of the linear motion link 82 is fixed by the biasing member 9, and it is possible to prevent the shutter 64 from moving inadvertently from the open position to the closed position.

[0176] In this manner, in the image forming apparatus 1, when the drum shaft 54a of the process cartridge 50 mounted in the apparatus main body 2 abuts against the abutment piece 80 of the link 8 and the drum shaft 54a moves the abutment piece 80, the shutter 64 moves from the closed position toward the open position, and before the shutter 64 moves to the open position, the abutment piece 80 and the drum shaft 54a separate, and the abutment piece 80, now separated from the drum shaft 54a, moves further in the direction in which the shutter 64 moves to the open position.

[0177] In this configuration, when the shutter 64 moves to the open position, the link 8 having the abutment piece 80 and the process cartridge 50 having the drum shaft 54a are separated from each other, so that the user's operation on the process cartridge 50 does not affect the open / closed state of the shutter 64. In addition, after the shutter 64 moves to the open position, there is no need to further move the link 8, and the movement range of the link 8 can be kept small.

[0178] In addition, when the process cartridge 50 is attached to the main body 2 of the apparatus, when the process cartridge 50 and the link 8 come into contact with each other and then the link 8 and the process cartridge 50 separate from each other, the pressing arm 91 of the urging member 9 presses the linear link 82 toward the second position.

[0179] As a result, even after the link 8 and the process cartridge 50 are separated, the link 8 is pressed toward the second position by the biasing member 9, so that the pressed link 8 can move the shutter 64 to the open position.

[0180] In particular, by pressing the second pressed surface 823b of the linear motion link 82 with the pressing arm 91, the link 8 can be moved toward the second position, and the shutter 64 can be moved to the open position.

[0181] In addition, when the process cartridge 50 mounted in the apparatus main body 2 comes into contact with the abutment piece 80 of the link 8, the pressing arm 91 comes into contact with the first pressed surface 823a of the link 8, and the link 8 is configured to move toward the second position so that the second pressed surface 823b of the link 8 comes into contact with the pressing arm 91 before the link 8 and the process cartridge 50 separate.

[0182] As a result, when the link 8 and the process cartridge 50 are separated, the pressing arm 91 abuts against the second pressed surface 823b, so that even after the link 8 and the process cartridge 50 are separated, the shutter 64 can be moved to the open position by the link 8.

[0183] 21 toward the mounting position, the drum shaft 54a moves from the middle part 241b to the rear part 241c of the cartridge rail 241, and then moves in the rear part 241c in the mounting direction. Thereafter, the process cartridge 50 reaches the mounting position as shown in FIG. 25, and is mounted in the apparatus main body 2.

[0184] (Operation when removing the process cartridge) Next, there will be described the operation of the link 8 when the process cartridge 50 in the mounting position is removed from the apparatus main body 2. When removing the process cartridge 50, the link 8 operates in the opposite manner to the operation when the process cartridge 50 is mounted.

[0185] As shown in Fig. 25, when the process cartridge 50 is attached to the apparatus main body 2, the drum shaft 54a is spaced rearward from the contact piece 80, and the contact piece 80 is located across the rear part 242c and the middle part 242b of the contact piece rail 242. Specifically, the first boss 803 of the contact piece 80 is located at the rear part 242c of the contact piece rail 242, and the second boss 804 is located at the middle part 242b (through hole 24C) of the contact piece rail 242. When the contact piece 80 is in the position shown in Fig. 25, the shutter 64 is moved to the open position by the link 8, as shown in Fig. 6(b).

[0186] 23, when the abutment piece 80 is in the position shown in Fig. 25, the abutment portion 912 of the pressing arm 91 abuts against the second pressed surface 823b of the linear link 82, restricting the forward movement of the linear link 82. As a result, when the shutter 64 is moved to the open position by the link 8, the linear link 82 is biased by the biasing member 9, and the shutter 64 does not move inadvertently from the open position to the closed position, so that the open position of the shutter 64 can be stably maintained.

[0187] When the process cartridge 50 in the mounting position shown in Fig. 25 is removed forward from the apparatus main body 2, the drum shaft 54a moves downstream in the removal direction within the rear portion 241c of the cartridge rail 241. The removal direction is the direction in which the process cartridge 50, which is extracted from the mounting main body 2, moves toward the outside of the mounting main body 2 when the process cartridge 50 is removed from the apparatus main body 2. As shown in Fig. 26, when the drum shaft 54a moving within the cartridge rail 241 reaches the middle portion 241b (through hole 24C), the drum shaft 54a abuts against the second boss 804 of the abutment piece 80.

[0188] 27, the contact piece 80 in contact with the drum shaft 54a is pressed by the drum shaft 54a and moves downstream in the removal direction of the process cartridge 50. That is, the contact piece 80 moves from a position where the first boss 803 is at the rear part 242c of the contact piece rail 242 to a position where it is at the middle part 242b (through hole 24C). In this case, the second boss 804 pressed by the drum shaft 54a moves from the middle part 242b (through hole 24C) of the contact piece rail 242 toward the front part 242a.

[0189] 28, when the abutment piece 80 moves, the first rotating link 81 moves forward while rotating in a direction in which the inclination angle with respect to the horizontal direction increases, and the linear link 82 moves forward linearly. In other words, the drum shaft 54a of the process cartridge 50 being detached from the image forming apparatus 1 abuts against the abutment piece 80 and presses the linear link 82 forward in a direction from the second position to the first position.

[0190] In this case, as the linear link 82 moves forward, the abutment portion 912 of the pressing arm 91 of the urging member 9 moves up the second pressed surface 823b of the linear link 82 against the pressing force of the pressing spring 92, and then rides from the second pressed surface 823b onto the first pressed surface 823a. That is, when the process cartridge 50 is removed from the apparatus main body 2, the pressing arm 91 abuts against the second pressed surface 823b and then against the first pressed surface 823a. In a state in which the pressing arm 91 abuts against the first pressed surface 823a, which is a surface extending in the horizontal direction, the restriction by the pressing member 9 of the shutter 64 moving from the open position to the closed position is released.

[0191] Furthermore, when the linear link 82 moves forward, the connecting hole 822 of the linear link 82 engages with the engaging pin 832a of the second rotating link 83, and the second rotating link 83 rotates in a direction in which the engaging pin 832a moves forward. When the second rotating link 83 rotates, the connecting hole 833a of the second rotating link 83 engages with the engaging pin 842 of the third rotating link 84, and the third rotating link 84 rotates in a direction in which the engaging pin 842 moves backward.

[0192] 29, when the process cartridge 50 is further removed from the apparatus main body 2, the abutment piece 80 is further moved downstream in the removal direction by the drum shaft 54a moving within the middle part 241b (through hole 24C) of the cartridge rail 241. In FIG. 29, the first boss 803 of the abutment piece 80 is located in the middle part 242b (through hole 24C) of the abutment piece rail 242, and the second boss 804 is located in the front part 242a of the abutment piece rail 242.

[0193] When the abutment piece 80 moves, the first rotating link 81 moves forward while rotating in a direction in which the inclination angle with respect to the horizontal direction becomes larger. When the first rotating link 81 rotates and moves, the linear motion link 82 moves further forward in a straight line. When the linear motion link 82 moves, the second rotating link 83 rotates further in the direction in which the engagement pin 832a moves forward. When the second rotating link 83 rotates, the third rotating link 84 rotates further in the direction in which the engagement pin 842 moves backward.

[0194] When the third rotating link 84 rotates, the coil spring 86 rotates along with the rotation of the third rotating link 84, and the arm portion 861 of the coil spring 86 engages with the engagement pin 854 of the shutter link 85 from above. When the arm portion 861 engages with the engagement pin 854, the shutter link 85 rotates in a direction in which the engagement portion 853 moves downward. This causes the shutter 64 to move from the open position toward the closed position.

[0195] In this case, the movement of the abutment piece 80 by the drum shaft 54a is transmitted to the linear link 82 via the first pivot link 81, so that even if the distance between the mounting position of the process cartridge 50 in the device main body 2 and the shutter 64 is large, it is possible to efficiently transmit driving force from the abutment piece 80 to the shutter 64.

[0196] As shown in FIG. 29, when the drum shaft 54a moves the abutment piece 80 until the second boss 804 is positioned at the front part 242a of the abutment piece rail 242, the linear link 82 moves forward, and as shown in FIG. 30, the abutment portion 912 of the pressing arm 91 in the biasing member 9 transfers from the first pressed surface 823a to the third pressed surface 823c of the linear link 82 due to the pressing force of the pressing spring 92.

[0197] In this case, the positional relationship between the pressing arm 91 and the link 8 is set so that when the drum shaft 54a moves the abutting piece 80 until the second boss 804 is positioned at the front part 242a of the abutting piece rail 242, the abutting portion 912 of the pressing arm 91 always abuts against the third pressed surface 823c. Furthermore, even if the abutting portion 912 of the pressing arm 91 abuts against the lowermost part of the third pressed surface 823c within the tolerance range of each member constituting the link 8, the abutting portion 912 is set not to come into contact with the upper surface 82A located rearward of the third pressed surface 823c.

[0198] As shown in Figure 31, after the abutment piece 80 moves until the second boss 804 is positioned at the front part 242a of the abutment piece rail 242 and the abutment portion 912 abuts against the third pressed surface 823c, the drum shaft 54a, which has moved the abutment piece 80 until the second boss 804 is positioned at the front part 242a of the abutment piece rail 242, moves from the middle part 241b to the front part 241a of the cartridge rail 241, and the abutment piece 80 and the drum shaft 54a are separated from each other.

[0199] In addition, when the abutment piece 80 and the drum shaft 54a are separated from each other, the shutter 64 has not yet reached the closed position. In other words, the drum shaft 54a and the abutment piece 80 are separated from each other before the linear link 82, which is pressed by the drum shaft 54a and moves from the second position to the first position, reaches the first position.

[0200] After the abutment piece 80 moves until the second boss 804 is positioned at the front 242a of the abutment piece rail 242 and the abutment portion 912 abuts against the third pressed surface 823c, the second boss 804 and the drum shaft 54a are separated from each other, so that the drum shaft 54a does not move the abutment piece 80.

[0201] 30, since the abutment portion 912 of the pressing arm 91 abuts against the third pressed surface 823c, a pressing force is applied from the pressing arm 91 to the linear motion link 82 in a direction toward the first position, and the linear motion link 82 moves forward. In other words, after the drum shaft 54a and the abutment piece 80 are separated from each other, the linear motion link 82 is biased in a direction from the second position toward the first position by the biasing force of the biasing member 9, and reaches the first position.

[0202] As shown in FIG. 6(a), when the linear link 82 moves forward and reaches the first position due to the pressing force from the pressing arm 91, the shutter link 85 rotates in the direction in which the engagement portion 853 moves downward, and the shutter 64 moves to the closed position.

[0203] In this way, when the linear link 82 reaches the first position and the shutter 64 moves to the closed position, the abutment piece 80 of the link 8 and the process cartridge 50 are separated, so that the shutter 64 can be stably maintained in the closed position regardless of the position of the process cartridge 50 after it has separated from the abutment piece 80.

[0204] 32, when the linear link 82 moves forward by the pressing force from the pressing arm 91 until the shutter 64 moves to the closed position, the abutting portion 912 of the pressing arm 91 is set not to come into contact with the upper surface 82A located behind the third pressed surface 823c. This makes it possible to hold the shutter 64 in the closed position by the pressing force from the pressing arm 91.

[0205] Furthermore, as shown in FIG. 33, when the linear link 82 moves forward due to the pressing force from the pressing arm 91, the abutment piece 80 is pushed by the first pivot link 81 and moves forward, and the second boss 804 of the abutment piece 80 moves forward along the front part 242a of the abutment piece rail 242 from the position shown in FIG. 31.

[0206] When the shutter 64 moves to the closed position, the contact portion 64b comes into contact with the contact surface 632 of the fixing frame 63, and further movement is restricted, so that the shutter 64 can be held in the closed position.

[0207] In this way, when the process cartridge 50 mounted in the apparatus main body 2 is removed from the apparatus main body 2, the abutment piece 80 of the link 8 comes into contact with the drum shaft 54a of the process cartridge 50, and the link 8 moves in a direction in which the shutter 64, which is in the open position, moves to the closed position. Therefore, accompanying the operation of removing the process cartridge 50 from the apparatus main body 2, it is possible to move the shutter 64 to the closed position.

[0208] As described above, in the image forming apparatus 1, when the process cartridge 50 is attached to the apparatus main body 2, the drum shaft 54a abuts against the first boss 803 of the abutment piece 80, causing the link 8 to move in the direction in which the shutter 64 moves from the closed position to the open position, and when the process cartridge 50 is removed from the apparatus main body 2, the drum shaft 54a abuts against the second boss 804 of the abutment piece 80, causing the link 8 to move in the direction in which the shutter 64 moves from the open position to the closed position.

[0209] That is, in the image forming apparatus 1, the shutter 64 moves to the open position when the process cartridge 50 is attached to the image forming apparatus 1, and moves to the closed position when the process cartridge 50 is removed from the image forming apparatus 1. With this configuration, the shutter 64 can be moved to the open position and the closed position in association with the operation of attaching or detaching the process cartridge 50 to or from the image forming apparatus 1. Also, with a simple configuration, it is possible to operate the link 8 both when the process cartridge 50 is attached and when it is removed.

[0210] Furthermore, in the image forming apparatus 1, the link 8 is configured to be displaced by the process cartridge 50, which is an operating member operated by the user, so that the shutter 64 can be opened and closed in conjunction with the user's operation.

[0211] [Operation when a force is applied to the shutter in the closed position toward the open position] As shown in FIG. 6(a), when link 8 is in the first position and shutter 64 is moving to the closed position, engagement pin 854 of shutter link 85 is pressed by arm 861 of coil spring 86 in a direction in which shutter 64 moves to the closed position.

[0212] In other words, when the third rotating link 84 is in the first position, the coil spring 86 abuts against the shutter link 85 and presses the shutter link 85 in a direction in which the shutter 64 moves to the closed position. In this state, a gap exists between the arm portion 861 of the coil spring 86 and the inner peripheral surface 844b of the connecting hole 844 in the operation cam 843.

[0213] Furthermore, when the link 8 is in the first position and the shutter 64 is moved to the closed position, the linear motion link 82 of the link 8 is pressed by the biasing member 9 in a direction in which the shutter 64 moves to the closed position.

[0214] In this case, the pressing force of the biasing member 9 that presses the linear link 82 in the direction in which the shutter 64 moves to the closed position is set to be greater than the pressing force of the coil spring 86 that presses the engagement pin 854 of the shutter link 85 in the direction in which the shutter 64 moves to the closed position.

[0215] When the link 8 is in the first position and the shutter 64 is moving to the closed position, if a force is applied to the shutter 64 toward the open position and the force applied to the shutter 64 is greater than the pressing force of the coil spring 86 against the shutter link 85, the shutter link 85 moves in the direction in which the shutter 64 moves toward the open position against the pressing force of the coil spring 86.

[0216] 34, when the shutter link 85 moves in a direction toward the open position of the shutter 64, the pressing force of the biasing member 9 is set to be greater than the pressing force of the coil spring 86, so the third rotating link 84 connected to the linear link 82 does not rotate, and the arm 861 of the coil spring 86 elastically deforms and moves upward. In this case, because a gap exists between the arm 861 and the inner circumferential surface 844b of the connecting hole 844, the arm 861 that has moved upward does not interfere with the inner circumferential surface 844b.

[0217] In other words, when the third rotating link 84 is in the first position, if the shutter 64 moves from the closed position to the open position, the coil spring 86 in contact with the shutter link 85 elastically deforms, and the third rotating link 84 maintains its state in the first position. In this way, the third rotating link 84 of the link 8 is configured not to move from the first position to the second position when a force toward the open position is applied to the shutter 64 in the closed position.

[0218] If, for example, the shutter 64 moves from the closed position to the open position while the third pivot link 84 is in the first position, and the third pivot link 84 moves from the first position to the second position, the abutment piece 80 connected to the third pivot link 84 via the linear link 82 or the like will move as the third pivot link 84 moves.

[0219] When the abutment piece 80 moves, the second boss 804 of the abutment piece 80, which was located at the front part 242a of the abutment piece rail 242, comes out to the middle part 242b (through hole 24C) of the abutment piece rail 242, and when an attempt is subsequently made to attach the process cartridge 50 to the apparatus main body 2, the drum shaft 54a interferes with the second boss 804 and is unable to abut against the first boss 803, which may hinder normal operation of the link 8.

[0220] However, in the image forming device 1, when the third pivot link 84 is in the first position and the shutter 64, which is in the closed position, moves toward the open position, the coil spring 86 abutting the shutter link 85 elastically deforms, and the third pivot link 84 does not move and remains in the first position, thereby preventing the subsequent operation of the link 8 from being hindered.

[0221] In this embodiment, the link 8 has the abutment piece 80, the first rotating link 81, the linear link 82, the second rotating link 83, the third rotating link 84, the shutter link 85, and the coil spring 86, but is not limited to this, and for example, a configuration in which one link connected to the shutter 64 abuts against the process cartridge 50 is also possible. Furthermore, the movement of each link of the link 8 is not limited to the movement in this embodiment, and may be a movement other than rotation or linear movement.

[0222] In this embodiment, the shutter 64 is opened and closed by the drum shaft 54a of the process cartridge 50 abutting against the abutment piece 80 of the link 8, but this is not limited to this and another part of the process cartridge 50 may abut against the link 8.

[0223] In this embodiment, the urging member 9 has the pressing spring 92 and the pressing arm 91 that is pressed by the pressing spring 92 and comes into contact with the upper surface 82A of the linear motion link 82, but the present invention is not limited to this and may be in a shape other than a spring or an arm as long as it is configured to press the link 8. Furthermore, the pressing direction of the pressing spring 92 may be configured to press in another direction such as the left-right direction, the up-down direction, the front-rear direction, etc., other than the downward pressing direction as in this embodiment.

[0224] In this embodiment, when the shutter 64 moves to the open position, the abutment end 64a abuts against the abutment surface 631 of the fixing frame 63, and the shutter 64 is positioned at the open position, but the present invention is not limited to this, and the shutter 64 may be positioned at the open position by abutment of a part of the link 8. For example, the abutment surface that abuts against the linear link 82 or the shutter link 85 when the linear link 83 or the shutter link 85 opens the shutter 64 to the maximum may be on the device body 2. Similarly, when the shutter 64 moves to the closed position, the abutment portion 64b abuts against the abutment surface 632 of the fixing frame 63, and the shutter 64 is positioned at the closed position, but the present invention is not limited to this, and the shutter 64 may be positioned at the closed position by abutment of a part of the device body and the link 8 when the shutter 64 moves to the maximum closed position.

[0225] [Second embodiment of the operating member for moving the link] As shown in Fig. 35, the front cover 21 can be used as an operating member for moving a link that can move between a first position where the shutter is moved to a closed position and a second position where the shutter is moved to an open position. The front cover 21 is an example of an opening / closing cover that is an operating member operated by the user.

[0226] 35, link 8A can move between a first position and a second position in response to operation of front cover 21. Link 8A differs from link 8 in that it does not include abutment piece 80 and first rotating link 81, and includes linear link 182 instead of linear link 82.

[0227] The front cover 21 is movable between an open position and a closed position by rotating about a rotation shaft 21a.

[0228] The linear link 182 is a substantially linear member that is rotatably connected to the front cover 21 and extends in the front-rear direction. The linear link 182 has a fitting portion 1821 located at the front end portion into which the boss 21b of the front cover 21 is rotatably fitted, and a connecting hole 1822 located at the rear end portion. The linear link 182 is connected to the front cover 21 by fitting the boss 21b into the fitting portion 1821, and moves linearly in the front-rear direction along with the rotation of the front cover 21.

[0229] The linear link 182 moves from the front to the rear as the front cover 21 rotates from the open position to the closed position. This causes the link 8A to move the shutter 64 from the closed position to the open position. Conversely, the linear link 182 moves from the rear to the front as the front cover 21 rotates from the closed position to the open position. This causes the link 8A to move the shutter 64 from the open position to the closed position.

[0230] That is, when the front cover 21 is in the closed position, the shutter 64 moves to the open position, and when the front cover 21 is in the open position, the shutter 64 moves to the closed position. The position of the linear link 182 that moves the shutter 64 to the closed position is the first position, and the position of the linear link 182 that moves the shutter 64 to the open position is the second position.

[0231] The engaging pin 832a of the second rotating link 83 enters the connecting hole 1822 of the linear link 182 from the right, and is configured so that the engaging pin 832a and the connecting hole 1822 engage with each other as the linear link 182 moves in the front-rear direction. The linear link 182 is connected to the second rotating link 83 by the engaging pin 832a and the connecting hole 1822 engaging with each other.

[0232] This allows link 8A to move shutter 64 from the closed position to the open position as front cover 21 rotates from the open position to the closed position, and link 8A to move shutter 64 from the open position to the closed position as front cover 21 rotates from the closed position to the open position.

[0233] In this way, by using the front cover 21 as an operating member for moving the link 8A, it is possible to move the shutter 64 between an open position and a closed position in conjunction with the action of opening and closing the front cover 21. [Explanation of symbols]

[0234] 1, 1A Image forming device 2. Device body 6 Fixing unit 8, 8A Link 9. Pressing member 21 Front cover 24 First body frame 24A Front frame 50 Process Cartridge 54 Photosensitive drum 54a Drum shaft 61 Heating unit 62 Pressure roller 63 Fixing Frame 64 Shutter 80 Contact piece 81 First rotating link 82, 182 Linear link 82A top surface 84 3rd Rotating Link 85 Shutterlink 86 Coil Spring 91 Pressing arm 92 Compression spring 241 Cartridge Rail 242 Single rail abutment 631 Contact surface 632 Contact surface 803 First Boss 804 Second Boss 823 Link protrusion 823a First pressed surface 823b 2nd pressed surface 823c 3rd pressed surface 911 Support part 912 Contact part NP Nip S Seat

Claims

1. a fixing device having a heating section and a pressure section that forms a nip with the heating section, and fixing the toner image onto the sheet; a shutter that is displaceable between a closed position that covers a portion of the heating unit and an open position that opens a portion of the heating unit; an urging member that, when the shutter is in a closed position, urges the shutter to be held in the closed position, and, when the shutter is in an open position, urges the shutter to be held in the open position.

2. The image forming apparatus according to claim 1 , further comprising a switching mechanism that switches a biasing direction of the biasing member between a biasing direction for holding the shutter at the closed position and a biasing direction for holding the shutter at the open position.

3. 3. The image forming apparatus according to claim 2, further comprising, as the switching mechanism, a link connected to the shutter and displaceable between a first position in which the shutter is displaced to a closed position and a second position in which the shutter is displaced to an open position, and the biasing member biases the link.

4. 4. The image forming apparatus according to claim 3, wherein the biasing member includes a spring that biases the link, and a pressing portion that is connected to the spring and presses the link.

5. The link is: a first portion that comes into contact with the pressing portion when the link is in the first position and converts the biasing direction of the spring into a direction in which the link is directed from the second position to the first position; 5. The image forming apparatus according to claim 4, further comprising: a second portion that abuts against the pressing portion when the link is in the second position, thereby converting the biasing direction of the spring into a direction in which the link is directed from the first position to the second position.

6. the first portion of the link is a first inclined surface inclined with respect to a moving direction of the link, the second portion of the link is a second inclined surface inclined with respect to a moving direction of the link, 6. The image forming apparatus according to claim 5, wherein a direction of inclination of the first inclined surface and a direction of inclination of the second inclined surface are different from each other.

7. The spring of the biasing member biases the pressing portion downward, the first inclined surface of the link has an inclined shape that rises along a moving direction of the link from the second position toward the first position, The image forming apparatus according to claim 6 , wherein the second inclined surface of the link has an inclination shape that rises along a moving direction of the link from the first position toward the second position.

8. 5. The image forming apparatus according to claim 4, wherein the pressing portion is an arm having a rotation center at one end and a contact portion at the other end that contacts the link.

9. The image forming apparatus according to claim 3 , further comprising an operating member operable by a user to displace the link.

10. The image forming apparatus according to claim 9, wherein the operating member is a cartridge that is detachable from the image forming apparatus, and the shutter moves to the open position when the cartridge is attached to the image forming apparatus, and the shutter moves to the closed position when the cartridge is removed from the image forming apparatus.

11. The cartridge has a photosensitive drum that rotates around a drum axis, 11. The image forming apparatus according to claim 10, wherein the link has a contact piece that contacts the drum shaft, a first link that contacts the urging member, and a second link that is rotatably connected to the first link and to the contact piece.

12. the drum shaft of the cartridge to be removed from the image forming apparatus comes into contact with the abutment piece and presses the first link in a direction from the second position toward the first position, The drum shaft and the abutment piece are separated from each other before the first link, which is pressed by the drum shaft to move from the second position to the first position, reaches the first position, 12. An image forming apparatus as described in claim 11, wherein after the drum shaft and the abutment piece separate, the first link is urged in a direction from the second position toward the first position by the urging force of the urging member to reach the first position.

13. The image forming apparatus according to claim 1 , further comprising a regulating surface that comes into contact with the shutter when the shutter is in the closed position to regulate the position of the shutter.

14. 2 . The image forming apparatus according to claim 1 , wherein the link is configured not to move from the first position to the second position when a force toward the open position is applied to the shutter in the closed position.

15. The link is: a shutter link coupled to the shutter for moving the shutter between the open position and the closed position; a link cam connected to the shutter link and movable between the first position and the second position; a link spring that moves along with the movement of the link cam to press the shutter link, When the link cam is in the first position, the link spring abuts against the shutter link and urges the shutter link in a direction in which the shutter moves to the closed position, 15. An image forming apparatus as described in claim 14, wherein when the link cam is in the first position and the shutter moves from the closed position toward the open position, the link spring abutting the shutter link elastically deforms, and the link cam maintains its state in the first position.

16. the image forming apparatus includes an opening, and an opening / closing cover as the operation member that is movable between a closing position for closing the opening and an opening position for opening the opening; When the opening / closing cover is in the closed position, the shutter moves to the open position, 10. The image forming apparatus according to claim 9, wherein the shutter moves to the closed position when the opening / closing cover is in the open position.

Images