Image forming apparatus

Abstract

To provide an image forming apparatus that can prevent inadvertent opening of a shutter of a fuser.SOLUTION: An apparatus main body 2 of an image forming apparatus 1 comprises: a front frame 24A that guides a drum shaft 54a when a process cartridge 50 is mounted in the apparatus main body 2; and a coupling link 8 that moves a shutter 64 of a fuser 6 from a closed position to an open position when the process cartridge 50 is mounted in the apparatus main body 2, and moves the shutter 64 from the open position to the closed position when the process cartridge 50 is removed from the apparatus main body 2. The front frame 24A has a through hole 24C. When the process cartridge 50 is mounted in the apparatus main body 2, the drum shaft 54a enters the through hole 24C. The coupling link 8 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, and is in contact with the drum shaft 54a of the process cartridge 50 mounted in the apparatus main body 2 through the through hole 24C.SELECTED DRAWING: Figure 14

Description

Technical Field

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

Background Art

[0002] Conventionally, in an image forming apparatus provided with a detachable cartridge, in order to prevent a user's hand from contacting a fixing device having a heating member, a shutter is provided in front of the fixing device.

[0003] For example, in the image forming apparatus disclosed in Patent Document 1, a link member that is connected to the shutter and can abut on the cartridge is provided. When the cartridge is mounted, the link member abuts on the cartridge and moves, and the shutter is configured to open along with the movement of the link member. Further, when the cartridge is detached, the link member moves to the opposite side by a spring force, and the shutter is configured to close.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] As described above, in an image forming apparatus provided with a link member connected to a shutter, if the link member is located within the accommodation space of the cartridge, when the cartridge is detached from the accommodation space, it is easy for the user to contact the link member, and there is a risk that the shutter may be inadvertently opened.

[0006] Therefore, the present invention provides an image forming apparatus having a configuration in which a shutter opens and closes according to the attachment and detachment of a cartridge, and capable of suppressing the shutter from being inadvertently opened.

Means for Solving the Problems

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

[0008] That is, the image forming apparatus comprises an apparatus body, a cartridge detachably mounted on the apparatus body and including at least one of a photosensitive drum, a developing roller, and a toner container, and having guide projections, and a fuser for fixing the toner image transferred to a conveyed sheet, the fuser comprising a heater, a fixing frame covering the heater and having an opening formed on the upstream side of the heater in the sheet conveying direction, and a shutter that moves between a closed position that closes the opening and an open position that opens the opening, wherein the apparatus body is a guide frame that guides the guide projections when the cartridge is mounted on the apparatus body The device comprises a connecting link which is connected to the shutter and moves the shutter from the closed position to the open position when the cartridge is mounted on the device body, and moves the shutter from the open position to the closed position when the cartridge is detached from the device body, wherein the guide frame has a through hole, the guide projection enters the through hole when the cartridge is mounted on the device body, and the connecting link is located on the opposite side of the guide frame from the cartridge mounted on the device body and contacts the guide projection of the cartridge mounted on the device body via the through hole.

[0009] This prevents the user from coming into contact with the connecting link when the cartridge is detached from the device body, and prevents the connecting link from moving and unintentionally opening the shutter.

[0010] Furthermore, the device body has a lock that restricts the movement of the connecting link when the shutter is moved to the open or closed position.

[0011] This prevents the shutter from unintentionally moving from the open or closed position.

[0012] Furthermore, the connecting link includes a contact piece that abuts against the guide projection, a first rotating link connected to the contact piece and rotating along the movement of the contact piece, and a linear link connected to the first rotating link and moving linearly along the rotation of the first rotating link.

[0013] This allows for efficient transmission of driving force from the contact piece to the shutter, even if there is a distance between the cartridge mounted on the main body of the device and the fuser.

[0014] Furthermore, the lock restricts the movement of the linear link by pressing on the linear link.

[0015] Thus, since the lock restricts the movement of the linear link by pressing on it, the lock can be constructed with a simple structure.

[0016] Furthermore, the linear link has a link projection that protrudes toward the lock side, and the lock has an arm and a spring that biases the tip of the arm toward the linear link side, and the tip of the arm moves over the link projection as the linear link moves and is located on one side or the other side of the link projection in the direction of movement of the linear link.

[0017] This allows the shutter to be stably maintained in either the open or closed position.

[0018] Furthermore, the contact piece has a first projection and a second projection located upstream of the first projection in the cartridge mounting direction, the first projection contacts the guide projection of the cartridge mounted on the device body, and the second projection contacts the guide projection of the cartridge detached from the device body.

[0019] This allows the connecting link to operate both when the cartridge is being inserted and when it is being removed, with a simple configuration.

[0020] Further, the guide frame has a cartridge rail for guiding the guide protrusion of the cartridge and a contact piece rail for guiding the contact piece, and a part of the cartridge rail and the contact piece rail overlaps, and the overlapping part of the cartridge rail and the contact piece rail is the through hole.

[0021] Thus, since a part of the cartridge rail and the contact piece rail overlaps, the member forming the cartridge rail and the member forming the contact piece rail can be made common.

[0022] Further, the cartridge has a photosensitive drum, and the guide protrusion is a metal drum shaft protruding in the axial direction of the photosensitive drum.

[0023] Thereby, it is not necessary to separately provide a guide protrusion for moving the contact piece on the cartridge, and the configuration of the cartridge can be simplified.

[0024] Further, the connecting link is connected to the linear motion link and includes a second rotation link that rotates along with the movement of the linear motion link, a third rotation link that is connected to the second rotation link and rotates along with the rotation of the second rotation link, and a shutter link that is connected to the third rotation link and moves along with the rotation of the third rotation link to move the shutter between an open position and a closed position.

[0025] Thereby, the front-rear direction space required when transmitting the driving force to the shutter can be reduced, and the size of the apparatus main body can be reduced.

Advantages of the Invention

[0026] According to the present invention, it is possible to prevent the user from contacting the connecting link, and suppress the connecting link from moving and the shutter of the fixing device from inadvertently opening.

Brief Description of the Drawings

[0027] [Figure 1]This is a central cross-sectional view showing an image forming apparatus. [Figure 2] This is a perspective view showing an image forming apparatus with the front cover in the open position. [Figure 3] This is a side cross-sectional view showing the fuser. [Figure 4] This is a perspective view showing the heating unit and pressure roller of the fuser. [Figure 5] (a) is a perspective view showing the fuser with the shutter in the closed position, and (b) is a perspective view showing the fuser with the shutter in the open position. [Figure 6] (a) is a side view showing the fuser with the shutter in the closed position, and (b) is a side view showing the fuser with the shutter in the open position. [Figure 7] This is a side cross-sectional view showing the fuser. [Figure 8] This is a perspective view showing the process cartridge. [Figure 9] This is a side view showing the process cartridge. [Figure 10] This is a side view showing the left side of the first main frame. [Figure 11] This is a side view showing the right side of the first main frame. [Figure 12] This is a side view showing a connecting link in which the first projection of the contact piece is located in the middle of the contact piece rail and the second projection is located in the front of the contact piece rail. [Figure 13] This is a side view showing the first main frame in a state where the process cartridge is in the mounting start position, the first projection of the contact piece is located in the middle of the contact piece rail, and the second projection is located in the front of the contact piece rail. [Figure 14] This is a diagram showing the contact piece. [Figure 15] This is a side view showing a connecting link in which the drum shaft is in contact with the contact piece, and both the first and second projections of the contact piece are located in the middle of the contact piece rail. [Figure 16] This is a side view showing the first main frame in a state where the drum shaft is in contact with the contact piece, and both the first and second projections of the contact piece are located in the middle of the contact piece rail. [Figure 17] This is a side view showing a connecting link in which the drum shaft is in contact with the contact piece, the first projection of the contact piece is located at the rear of the contact piece rail, and the second projection is located in the middle of the contact piece rail. [Figure 18] This is a side view showing the first main frame in a state where the drum shaft is in contact with the contact piece, the first projection of the contact piece is located at the rear of the contact piece rail, and the second projection is located in the middle of the contact piece rail. [Figure 19] This is a side view showing the first main frame in a state where the drum shaft is separated from the contact piece and the process cartridge is in the mounting position. [Figure 20] This is a side view showing a pressure spring that contacts the drum shaft and presses the process cartridge into place. [Figure 21] This is a side view showing the roller spring that presses against the pinch roller when the process cartridge is in the mounting position. [Modes for carrying out the invention]

[0028] Next, embodiments for carrying out the present invention will be described with reference to the attached drawings.

[0029] [Image forming apparatus] The image forming apparatus 1 shown in Figure 1 is an embodiment of an image forming apparatus equipped with a sheet transport device according to the present invention, and is a laser printer that forms an image on a sheet S by an electrophotographic method.

[0030] In the following explanation, the right side of Figure 1 is defined as the front side of the image forming apparatus 1, the left side of Figure 1 is defined as the rear side of the image forming apparatus 1, the front of the page in Figure 1 is defined as the left side of the image forming apparatus 1, and the back of the page in Figure 1 is defined as the right side of the image forming apparatus 1. Furthermore, the top and bottom sides of Figure 1 are defined as the top and bottom sides of the image forming apparatus 1, respectively.

[0031] The image forming apparatus 1 comprises a main body 2, a paper feeding unit 3, an image forming unit 5, a fuser 6, and a paper discharge unit 7.

[0032] The main body 2 houses the paper feeding unit 3, the image forming unit 5, the fuser unit 6, and the paper discharge unit 7. An opening 2A is located on the front of the main body 2, and the main body 2 has a front cover 21 that can open and close the opening 2A. The front cover 21 is configured to rotate around a pivot axis 21a at its lower end, and by rotating around the pivot axis 21a, it can move between a closed position that closes the opening 2A and an open position that opens the opening 2A.

[0033] The paper feeding unit 3 comprises a paper feeding tray 10 that supports the sheet S, a sheet transport unit 30, a transport roller pair 34, and a registration roller 35a. The paper feeding unit 3 is located at the bottom of the main body 2 of the device and transports the sheet S supported by the paper feeding tray 10 to the image forming unit 5. The image forming apparatus 1 has a transport path P for the sheet S from the paper feeding unit 3 through the image forming unit 5 to the paper discharge unit 7.

[0034] 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 sheet S from below. The pressure plate 12 is rotatable about a pivot point 12a at its rear end, and by rotating about the pivot point 12a, it can move up and down between a lowered position and an elevated position. The pressing plate 13 is located below the pressure plate 12 and can move the pressure plate 12 up and down between a lowered position and an elevated position.

[0035] The sheet transport unit 30 is a transport mechanism that separates and removes sheets S supported by the paper feed tray 10 one by one and transports them toward the image forming unit 5, and is equipped with a paper feed roller 31, a separation roller 32, and a separation pad 33.

[0036] The paper feed roller 31 is a roller for feeding the sheet S, supported by the paper feed tray 10, toward the separation roller 32. The separation roller 32 is located downstream of the paper feed roller 31 in the sheet transport direction, and the separation pad 33 is positioned opposite the separation roller 32 and is biased toward the separation roller 32.

[0037] The sheets S, fed towards the separation roller 32 by the paper feed roller 31, are separated one by one between the separation roller 32 and the separation pad 33. The separated sheets S are then fed into the transport path P.

[0038] The sheet S, which has been sent onto the transport path P, is transported toward the image forming unit 5 by the transport roller pair 34, the resist roller 35a, and the pinch roller 35b positioned opposite the resist roller 35a. The resist roller 35a restricts the movement of the leading edge of the transported sheet S, stopping it temporarily, and then transports the sheet S toward the image forming unit 5 at a predetermined timing.

[0039] The image forming unit 5 is located downstream of the paper feeding unit 3 in the sheet transport direction and forms an image on the sheet S transported from the paper feeding unit 3. The image forming unit 5 includes a process cartridge 50 that transfers an image to the surface of the sheet S transported from the paper feeding unit 3, a transfer roller 55 positioned opposite the photosensitive drum 54 of the process cartridge 50, and an exposure unit 56 that exposes the surface of the photosensitive drum 54.

[0040] The process cartridge 50 is located above the paper feed section 3 in the main body of the device 2 and includes a developer storage chamber 51, a supply roller 52, a developing roller 53, a photosensitive drum 54, etc. The process cartridge 50 supports a pinch roller 35b. The pinch roller 35b is an example of a driven roller.

[0041] The process cartridge 50 comprises a drum cartridge having a photosensitive drum 54 and a developing cartridge mounted on the drum cartridge and having a developing roller 53, and is detachably mounted on the device body 2. In this case, the process cartridge 50 is mounted on the device body 2 by inserting the drum cartridge and the developing cartridge mounted on the drum cartridge into the device body 2 as a single unit, and is detached from the device body 2 by removing the drum cartridge and the developing cartridge mounted on the drum cartridge from the device body 2 as a single unit.

[0042] The process cartridge 50 is an example of a cartridge that includes 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 device body 2 when the front cover 21 is in the open position.

[0043] The photosensitive drum 54 is positioned such that its axis X is aligned in the left-right direction when the process cartridge 50 is mounted on the main body 2 of the apparatus. The photosensitive drum 54 has a metal drum shaft 54a that extends along the direction of the axis X.

[0044] In this embodiment, the process cartridge 50 comprises a drum cartridge having a photosensitive drum 54 and a developing cartridge mounted on the drum cartridge and having a developing roller 53. However, it can also be configured to include a cartridge having a photosensitive drum 54 and a developing roller 53, and a toner box mounted on the cartridge for containing toner. The toner box is an example of a toner container. Furthermore, in an image forming apparatus, the drum cartridge having a photosensitive drum 54 and the developing cartridge having a developing roller 53 can be configured to be mounted separately on the main body 2 of the apparatus. That is, the process cartridge 50 is detachably mounted on the main body of the apparatus and includes at least one of the photosensitive drum, the developing roller, and the toner container.

[0045] The exposure unit 56 is equipped with a laser diode, a polygon mirror, a lens, and a reflector, 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.

[0046] The developer chamber 51 contains toner, which is the developer. The toner contained in the developer chamber 51 is agitated by an agitator (not shown) and sent to the supply roller 52. The supply roller 52 then supplies the toner sent from the developer chamber 51 to the developing roller 53.

[0047] The developing roller 53 is positioned in close contact with the supply roller 52 and carries positively charged toner supplied from the supply roller 52 by a sliding contact member (not shown). A developing bias is also applied to the developing roller 53 by a bias application means (not shown).

[0048] The photosensitive drum 54 is positioned 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 where the electrostatic latent image has been formed, causing the electrostatic latent image to become visible as a toner image.

[0049] The transfer roller 55 is positioned opposite the photosensitive drum 54, and a transfer bias is applied by a bias application means (not shown). With the transfer bias applied to the surface of the transfer roller 55, the sheet S is transported while being sandwiched between the photosensitive drum 54 on which the toner image has been formed and the transfer roller 55, thereby transferring the toner image formed on the surface of the photosensitive drum 54 to the surface of the sheet S. The sheet S on which the toner image has been transferred is then transported to the fuser 6.

[0050] The fuser 6 comprises a heating unit 61 and a pressure roller 62, and fixes the image transferred to the sheet S by the process cartridge 50. The heating unit 61 is heated by power supplied from a power source (not shown). The heating unit 61 is an example of a heater. The pressure roller 62 is positioned 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.

[0051] When the sheet S on which the toner image has been transferred is transported to the fuser unit 6, the sheet S is heated while being held between the heating unit 61 and the pressure roller 62, thereby fixing the toner image to the sheet S. In this way, the fuser unit 6 fixes the toner image transferred to the transported sheet S.

[0052] The paper discharge unit 7 is located downstream of the image forming unit 5 in the sheet transport direction and discharges the sheets S, on which images have been formed in the image forming unit 5, to the outside of the image forming apparatus 1. The paper discharge unit 7 comprises a pair of paper discharge rollers 71 and a paper discharge tray 72. The pair of paper discharge rollers 71 is configured to discharge the sheets S, which have been transported from the fuser 6 along the transport path P, toward the outside of the apparatus body 2. The paper discharge tray 72 is formed on the upper surface of the apparatus body 2 and supports the sheets S that have been discharged to the outside of the apparatus body 2 by the pair of paper discharge rollers 71.

[0053] As shown in Figure 2, the device body 2 comprises a first main frame 24 and a second main frame 25, which are spaced apart from each other in the left-right direction. The first main frame 24 is located at the right end of the device body 2, and the second main frame 25 is located at the left end of the device body 2. The first main frame 24 extends in the front-rear and up-down directions and is positioned so that its plate surface faces the left-right direction. The second main frame 25 extends in the front-rear and up-down directions and is positioned so that its plate surface faces the left-right direction.

[0054] The process cartridge 50 and fuser unit 6 are positioned between the first main frame 24 and the second main frame 25. The first main frame 24 is positioned to the right of the process cartridge 50 and fuser unit 6, and the second main frame 25 is positioned to the left of the process cartridge 50 and fuser unit 6. The process cartridge 50 is detachably supported by the first main frame 24 and the second main frame 25.

[0055] [Fuser] As shown in Figures 3 and 4, the heating unit 61 of the fuser 6 comprises 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, with the first surface 611A being supported by the holder 612.

[0056] The holder 612 is made of, for example, a resin material and has a guide surface 612a and a support wall 612b. The guide surface 612a contacts the inner circumferential surface 614a of the belt 614 and guides 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 is in contact with the 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 with greater rigidity than the holder 612, such as a steel plate, into a roughly U-shape in cross-section.

[0057] The belt 614 is an endless belt having heat resistance and flexibility, and comprises a metal tube made of a metal such as stainless steel, and a fluororesin layer covering the metal tube. The heater 611, holder 612, and stay 613 are arranged inside the belt 614. The belt 614 is configured to rotate around the heater 611, holder 612, and stay 613. The inner circumferential surface 614a of the belt 614 is in contact with the heater 611.

[0058] The pressure roller 62 has a metal shaft 62A and an elastic layer 62B covering the shaft 62A. The pressure roller 62 is pressed against the heater 611 via a belt 614. The pressure roller 62 forms a nip portion NP for heating and pressurizing the sheet S by sandwiching the belt 614 between itself and the heater 611. In other words, the pressure roller 62 heats and pressurizes the sheet S together with the heater 611 at the nip portion NP.

[0059] The pressure roller 62 is configured to rotate when a driving force is transmitted from the motor 4 of the image forming apparatus 1. By rotating, the pressure roller 62 causes the belt 614 to rotate due to the frictional force between the belt 614 and the sheet S held between the nip portion NP. As a result, the sheet S on which the toner image has been transferred is transported between the pressure roller 62 and the heated belt 614, and the toner image is heat-fixed.

[0060] As shown in Figures 1, 5 to 7, the fuser 6 has a fuser frame 63 that covers the heating unit 61 and the pressure roller 62. The fuser frame 63 holds the heating unit 61 and the pressure roller 62. The fuser frame 63 covers the periphery of the heating unit 61 and the pressure roller 62 and has a first opening 63a formed on the upstream side in the sheet conveying direction of the heating unit 61 and the pressure roller 62, and a second opening 63b formed on the downstream side in the sheet conveying direction of the heating unit 61 and the pressure roller 62. The first opening 63a is an example of an opening.

[0061] The fuser 6 has a shutter 64 supported by the fuser frame 63. The shutter 64 is located upstream of the first opening 63a in the sheet transport direction in the fuser frame 63 and is configured to rotate about a pivot axis that extends along the left-right direction. By rotating about the pivot axis, the shutter 64 can move between a closed position that closes the first opening 63a and an open position that opens the first opening 63a.

[0062] In this embodiment, the fuser 6 comprises a heating unit 61 having a heater 611 and a belt 614, and a pressure roller 62. However, the fuser 6 can also be configured to include a heating roller with a built-in heater and a pressure roller pressed against the heating roller. Alternatively, the fuser 6 can be configured to include a heating roller with a built-in heater and a pressure belt pressed against the heating roller by an elastic member.

[0063] [Drum shaft] As shown in Figures 8 and 9, the drum shaft 54a of the photosensitive drum 54 protrudes to the right from the right end of the process cartridge 50 along the axial X direction. In other words, the drum shaft 54a protrudes toward the first main frame 24 along the axial X direction. The drum shaft 54a is an example of a guide projection.

[0064] [First main frame] As shown in Figures 10 and 11, the first main frame 24 has a front frame 24A located in front of it and a rear frame 24B located behind the front frame 24A. The front frame 24A and the rear frame 24B are formed integrally and continuously in the front-rear direction. The front frame 24A of the first main frame 24 is an example of a guide frame.

[0065] The front frame 24A of the first main frame 24 has a cartridge rail 241 and a contact rail 242. The cartridge rail 241 is formed in a groove shape with the left side open. The cartridge rail 241 extends in the front-rear direction and is inclined downwards as it moves from front to rear.

[0066] 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 to the device body 2 and when the process cartridge 50 is removed from the device 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 to the device body 2 from front to rear and removed from the device body 2 from rear to front.

[0067] In this manner, the front frame 24A guides the drum shaft 54a by the cartridge rail 241 when the process cartridge 50 is mounted to the apparatus body 2 and when it is detached from the apparatus body 2.

[0068] The contact rail 242 is formed in a groove shape with the right side open. The contact rail 242 extends in the front-rear direction and is inclined downwards from front to rear.

[0069] The cartridge rail 241 has a front portion 241a located forward, a rear portion 241c located backward, 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 forward, a rear portion 242c located backward, and a middle portion 242b located between the front portion 242a and the rear portion 242c.

[0070] The central portion 241b of the cartridge rail 241 and the central portion 242b of the abutment rail 242 overlap and communicate with each other. The central portions 241b and 242b form a through hole 24C that penetrates the front frame 24A in the left-right direction.

[0071] In other words, the middle section 241b, which is part of the cartridge rail 241, and the middle section 242b, which is part of the contact rail 242, overlap, and the overlapping portion between the cartridge rail 241 and the contact rail 242 is the through hole 24C. In this way, because a portion of the cartridge rail 241 and the contact rail 242 overlap, it is possible to use the same components for forming the cartridge rail 241 and the contact rail 242.

[0072] The drum shaft 54a enters the through-hole 24C when the process cartridge 50 is mounted to the apparatus body 2 and when the process cartridge 50 is removed from the apparatus body 2.

[0073] The front portion 242a of the contact rail 242 is located above the front portion 241a of the cartridge rail 241, and the rear portion 242c of the contact rail 242 is located above the rear portion 241c of the cartridge rail 241.

[0074] [Sample Link] As shown in Figures 6, 12, and 13, the main body of the apparatus 2 is equipped with a connecting link 8 that connects to the shutter 64. The connecting link 8 moves the shutter 64 from the closed position to the open position when the process cartridge 50 is mounted on the main body of the apparatus 2, and moves the shutter 64 from the open position to the closed position when the process cartridge 50 is detached from the main body of the apparatus 2. In other words, the connecting link 8 is configured so that the shutter 64 opens and closes in accordance with the attachment and detachment of the process cartridge 50 to and from the main body of the apparatus 2. In the left-right direction, the connecting link 8 is located on the opposite side of the process cartridge 50 mounted on the main body of the apparatus 2 from the front frame 24A of the first main body frame 24.

[0075] The connecting link 8 includes a contact piece 80, a first rotational link 81, a linear link 82, a second rotational link 83, a third rotational link 84, a shutter link 85, and a coil spring 86.

[0076] 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 the contact piece rail 242, which guides the contact piece 80 as it moves in contact with the drum shaft 54a.

[0077] As shown in Figure 14, the contact piece 80 has a main body portion 801, a connecting portion 802, a first projection 803, and a second projection 804. The main body portion 801 is formed of a plate-shaped member with its plate surface facing in the left-right direction. The connecting portion 802 is a boss that protrudes to the right from the right surface of the main body portion 801.

[0078] The first projection 803 and the second projection 804 are pins that protrude to the left from the left side of the main body portion 801. The first projection 803 and the second projection 804 enter the contact rail 242 of the first main body frame 24 from the right side and are guided by the contact rail 242.

[0079] When the first projection 803 and the second projection 804 are engaged with the contact rail 242, the second projection 804 is located upstream of the first projection 803 in the direction in which the process cartridge 50 is mounted to the device body 2. The mounting direction is the direction in which the process cartridge 50 moves toward the mounting position when it is inserted into the device body 2.

[0080] The contact piece 80 is located on the opposite side of the process cartridge 50 mounted on the device body 2 relative to the front frame 24A of the first main frame 24. The first projection 803 and the second projection 804 are positioned so that, when they are engaged with the contact piece rail 242, they do not protrude further toward the process cartridge 50 than the front frame 24A of the first main frame 24.

[0081] The first projection 803 contacts the drum shaft 54a when the process cartridge 50 is mounted on the device body 2, and the second projection 804 contacts the drum shaft 54a when the process cartridge 50 is detached from the device body 2. In other words, the first projection 803 contacts the drum shaft 54a of the process cartridge 50 when it is mounted on the device body 2, and the second projection 804 contacts the drum shaft 54a of the process cartridge 50 when it is detached from the device body 2.

[0082] In this case, when the first projection 803 is located in the middle portion 242b (through hole 24C) of the contact rail 242, it contacts the drum shaft 54a of the process cartridge 50 mounted on the device body 2 via the through hole 24C. Also, when the second projection 804 is located in the middle portion 242b (through hole 24C) of the contact rail 242, it contacts the drum shaft 54a of the process cartridge 50 being detached from the device body 2 via the through hole 24C.

[0083] The drum shaft 54a, which contacts the first projection 803 and the second projection 804 through the through hole 24C, may contact the first projection 803 and the second projection 804 inside the through hole 24C, or it may contact the first projection 803 and the second projection 804 at a position that extends to the right of the through hole 24C in the left-right direction.

[0084] In this embodiment, the contact piece 80 is configured to move in contact with the drum shaft 54a. However, the process cartridge 50 may also be provided with a guide projection that protrudes toward the first main frame 24 side, separate from the drum shaft 54a, and the contact piece 80 may be configured to move in contact with this guide projection.

[0085] The first rotating link 81 is a substantially straight member connected to the contact piece 80. In the left-right direction, the first rotating link 81 is located to the right of the front frame 24A of the first main frame 24. The first rotating link 81 has a fitting portion 811 located at the front end into which the connecting portion 802 of the contact piece 80 fits, and a boss 812 located at the rear end that protrudes to the left. The first rotating link 81 is arranged in an inclined position in which the fitting portion 811 is located above and in front of the boss 812. The first rotating link 81 is connected to the contact piece 80 by the fitting portion 811 into which the connecting portion 802 fits, and rotates along with the movement of the contact piece 80.

[0086] The linear motion link 82 is a substantially straight member that is connected to the first rotational motion link 81 and extends in the front-rear direction. In the left-right direction, the linear motion link 82 is located to the right of the front frame 24A of the first main frame 24. The linear motion link 82 has a fitting portion 821 at its front end into which the boss 812 of the first rotational motion link 81 fits, and a connecting hole 822 at its rear end. The linear motion link 82 is connected to the first rotational motion link 81 by the fitting of the boss 812 into the fitting portion 821, and moves linearly in the front-rear direction along with the rotation of the first rotational motion link 81.

[0087] The second pivot link 83 is connected to the linear link 82 and supported by the first main frame 24. The second pivot link 83 has a support portion 831 that is rotatably supported by the first main frame 24, a first arm 832 that extends substantially downward from the support portion 831, and a second arm 833 that extends substantially upward from the support portion 831. An engagement pin 832a that protrudes to the left 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.

[0088] 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 pivot link 83 is connected to the linear link 82 by the engagement of the engagement pin 832a with the connecting hole 822 and rotates around the support portion 831 as the linear link 82 moves.

[0089] The third pivot link 84 is connected to the second pivot link 83 and is rotatably supported on the support shaft 65 of the fuser 6. The third pivot link 84 has a support portion 841 that is rotatably supported on the support shaft 65, an engagement pin 842 that protrudes to the right from the support portion 841, and a connecting hole 843 that is formed at a different phase from the engagement pin 842 in the circumferential direction of the support portion 841.

[0090] The engagement pin 842 of the third pivot link 84 enters the connecting hole 833a of the second pivot link 83 from the left and engages with the connecting hole 833a as the second pivot link 83 rotates. The third pivot link 84 is connected to the second pivot link 83 by the engagement of the engagement pin 842 with the connecting hole 833a, and rotates around the support shaft 65 in accordance with the rotation of the second pivot link 83.

[0091] As shown in Figures 5 and 6, the shutter link 85 is connected to the third pivot link 84 and is rotatably supported on the support shaft 65 of the fuser 6. The shutter link 85 moves along with the movement of the third pivot link 84, moving the shutter 64 of the fuser 6 between the closed and open positions. The shutter link 85 is located at the right end of the fuser 6 and has a support portion 851, an arm portion 852, an engaging portion 853, and an engaging pin 854.

[0092] The support portion 851 is rotatably supported by a support shaft 65 that protrudes to the right 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 engaging portion 853 is located at the front end of the arm portion 852 and has an elongated oval-shaped engaging hole 853a that is long in the front-rear direction. An opening / closing pin 641 that protrudes to the right from the right end of the shutter 64 engages with the engaging hole 853a.

[0093] The shutter link 85 is rotatable around the support portion 851 in a direction in which the engaging portion 853 moves up and down. When the shutter link 85 rotates and the engaging portion 853 moves downward, the shutter 64 moves to the closed position (see Figures 5(a) and 6(a)). When the shutter link 85 rotates and the engaging portion 853 moves upward, the shutter 64 moves to the open position (see Figures 5(b) and 6(b)).

[0094] The engagement pin 854 protrudes to the right from the support portion 851 side end of the arm portion 852. The engagement pin 854 of the shutter link 85 enters the connecting hole 843 of the third rotation link 84 from the left.

[0095] The coil spring 86 is supported by the support portion 841 of the third rotation link 84. The coil spring 86 has a first arm portion 861 and a second arm portion 862. The first arm portion 861 extends from the inner diameter side to the outer diameter side of the connecting hole 843 and enters into the connecting hole 843. The second arm portion 862 extends from the inner diameter side to the outer diameter side of the connecting hole 843 at a different phase than the first arm portion 861 in the circumferential direction and enters into the connecting hole 843.

[0096] The first arm 861 is located above the engagement pin 854 within the connecting hole 843, and the second arm 862 is located below the engagement pin 854 within the connecting hole 843. The coil spring 86 is rotatable along with the rotation of the third pivot link 84, and as the third pivot link 84 rotates, the first arm 861 or the second arm 862 engages with the engagement pin 854. The shutter link 85 is connected to the third pivot link 84 by the engagement pin 854 engaging with the first arm 861 or the second arm 862, and moves along the rotation of the third pivot link 84 to move the shutter 64 between the closed and open positions.

[0097] In the image forming apparatus 1, when the process cartridge 50 is attached to or detached from the apparatus body 2, the contact piece 80 of the connecting link 8 comes into contact with the drum shaft 54a and moves along the contact piece rail 242, thereby transmitting driving force to the shutter 64 via the connecting link 8, and the shutter 64 moves between the closed position and the open position.

[0098] In this embodiment, the connecting link 8 was configured to include a contact piece 80, a first rotational link 81, a linear link 82, a second rotational link 83, a third rotational link 84, a shutter link 85, and a coil spring 86. However, it is not limited to this configuration, and may be composed of a single link that connects to the shutter 64 and contacts the process cartridge 50 to open and close the shutter 64. Furthermore, the movement of the connecting link 8 is not limited to rotation or sliding, but 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.

[0099] [rock] As shown in Figure 12, the device body 2 is equipped with a lock 9 that restricts the movement of the connecting link 8 when the shutter 64 is moved to the open or closed position. Specifically, the lock 9 restricts the movement of the linear motion link 82 in the forward and backward direction by pressing on the linear motion link 82. The lock 9 has an arm 91 that contacts the upper surface 82A of the linear motion link 82, and a lock spring 92 that biases the tip of the arm 91 toward the upper surface 82A side of the linear motion link 82. The lock spring 92 is an example of a spring that biases the tip of the arm toward the linear motion link side.

[0100] The arm 91 has a support portion 911 located at the base end of the arm 91 and rotatably supported by the first main frame 24, a contact portion 912 located at the tip of the arm 91 that abuts against the upper surface 82A of the linear link 82, and a fitting portion 913 into which the lock spring 92 is fitted. The contact portion 912 is an example of the tip of the arm 91. The 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 vertical direction around the support portion 911.

[0101] The lock spring 92 is supported by the first main frame 24, and its lower end is fitted into the fitting portion 913 of the arm 91. The lock spring 92 biases the contact portion 912 of the arm 91 downward toward the upper surface 82A side of the linear link 82, and the contact portion 912 is pressed against the upper surface 82A.

[0102] The upper surface 82A of the linear link 82 has a link projection 823 that protrudes upward toward the lock 9 side between the fitting portion 821 and the connecting hole 822. The link projection 823 is formed in a mountain shape with a first inclined surface 823a that slopes downward toward the rear and a second inclined surface 823b that is formed continuously in front of the first inclined surface 823a and slopes downward toward the front.

[0103] The contact portion 912 of the arm 91 can overcome the link projection 823 against the biasing force of the lock spring 92 as the linear motion link 82 moves in the front-rear direction, and can be positioned on the rear side facing the first inclined surface 823a of the link projection 823, or on the front side facing the second inclined surface 823b of the link projection 823. The front side of the link projection 823 is an example of one side of the link projection, and the rear side of the link projection 823 is an example of the other side of the link projection.

[0104] When the contact portion 912 of the arm 91 is located behind the link projection 823, the contact portion 912 and the first inclined surface 823a engage, restricting the rearward movement of the linear link 82. When the contact portion 912 of the arm 91 is located in front of the link projection 823, the contact portion 912 and the second inclined surface 823b engage, restricting the forward movement of the linear link 82.

[0105] In other words, the arm 91 contacts the upper surface 82A of the linear link 82 at the rear of the link projection 823, pressing against the linear link 82 and thereby restricting the rearward movement of the linear link 82 and fixing the operation of the connecting link 8. Also, the arm 91 contacts the upper surface 82A of the linear link 82 at the front of the link projection 823, pressing against the linear link 82 and thereby restricting the forward movement of the linear link 82 and fixing the operation of the connecting link 8. Thus, because the lock 9 restricts the movement of the linear link 82 by the arm 91 pressing against the linear link 82, the lock 9 can be constructed with a simple structure.

[0106] The lock 9 is not limited to this embodiment. For example, the lock 9 may not be provided separately from the connecting link 8, and the connecting link 8 may maintain the shutter 64 in the open or closed position.

[0107] [How linked links work] Next, we will explain the operation of link 8.

[0108] (Operation when process cartridge is installed) First, we will explain the operation of the connecting link 8 when the process cartridge 50 is attached to the main unit 2 of the device.

[0109] As shown in Figures 12 and 13, when the process cartridge 50 is detached from the main body 2, and when the tip 50A of the process cartridge 50 in the insertion direction is in the mounting start position (the position shown in Figure 13) inserted into the main body 2, the drum shaft 54a is spaced apart from the contact piece 80, and the contact piece 80 is positioned across the front 242a and middle 241b of the contact piece rail 242. Specifically, the contact piece 80 is fitted into the contact piece rail 242 with the first projection 803 located in the middle 242b (through hole 24C) of the contact piece rail 242 and the second projection 804 located in the front 242a of the contact piece rail 242. The insertion direction of the process cartridge 50 is the same as the mounting direction.

[0110] When the contact piece 80 is in the position shown in Figure 13, the shutter 64 is moved to the closed position by the connecting link 8, as shown in Figure 6(a). This prevents the user's hand from touching the heating unit 61 of the fuser unit 6, even if the user inserts their hand into the device body 2 through the opening 2A when the process cartridge 50 is detached from the device body 2.

[0111] Furthermore, when the contact piece 80 is in the position shown in Figure 13, the contact portion 912 of the arm 91 in the lock 9 is located behind the link projection 823 of the linear link 82, restricting the rearward movement of the linear link 82. As a result, when the shutter 64 is moved to the closed position by the connecting link 8, the linear link 82 is fixed by the lock 9, and the shutter 64 does not unintentionally move from the closed position to the open position. In other words, in the lock 9, the contact portion 912 located behind the link projection 823 engages with the link projection 823, thereby restricting the movement of the linear link 82, and thus the closed position of the shutter 64 can be stably maintained.

[0112] Furthermore, the connecting link 8 is positioned on the opposite side of the process cartridge 50 mounted on the device body 2 relative to the front frame 24A of the first main frame 24, and the first projection 803 and second projection 804 of the contact piece 80 are positioned so as not to protrude further toward the process cartridge 50 than the front frame 24A of the first main frame 24. Therefore, when the process cartridge 50 is detached from the device body 2, it is possible to prevent the user from coming into contact with the contact piece 80, and to suppress the movement of the connecting link 8 and the unintentional opening of the shutter 64.

[0113] As shown in Figures 15 and 16, when the process cartridge 50, which is in the mounting starting position, is further inserted toward the mounting position, the drum shaft 54a enters the front part 241a of the cartridge rail 241 and moves within the cartridge rail 241. When the drum shaft 54a, which is moving within the cartridge rail 241, enters the middle part 241b (through hole 24C), the drum shaft 54a comes into contact with the first projection 803 of the contact piece 80.

[0114] The contact piece 80, which comes into contact with the drum shaft 54a as it moves 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. In Figure 16, the first projection 803 and the second projection 804 of the contact piece 80, which moves in contact with the drum shaft 54a, are both located in the middle portion 242b (through hole 24C) of the contact piece rail 242.

[0115] As the contact piece 80 moves, the first pivot link 81 connected to the contact piece 80 rotates in a direction that reduces its angle of inclination with respect to the horizontal, and moves backward. As the first pivot link 81 rotates and moves, the linear link 82 connected to the first pivot link 81 moves linearly backward.

[0116] When the linear link 82 moves, the connecting hole 822 of the linear link 82 engages with the engagement pin 832a of the second pivot link 83, causing the second pivot link 83 to rotate in the direction in which the engagement pin 832a moves backward. When the second pivot link 83 rotates, the connecting hole 833a of the second pivot link 83 engages with the engagement pin 842 of the third pivot link 84, causing the third pivot link 84 to rotate in the direction in which the engagement pin 842 moves forward.

[0117] In this case, as the linear link 82 moves backward, the contact portion 912 of the arm 91 in the lock 9 moves up the first inclined surface 823a of the link projection 823 of the linear link 82 against the biasing force of the lock spring 92, and rides up onto the top of the link projection 823.

[0118] When the contact portion 912 is riding on the top of the link projection 823, the lock spring 92 is compressed, increasing the biasing force on the contact portion 912 compared to when the contact portion 912 is located on the rear or front side of the link projection 823, and the pressing load of the contact portion 912 on the linear link 82 by the lock spring 92 becomes maximum.

[0119] As shown in Figures 17 and 18, when the process cartridge 50 is further inserted from the position shown in Figure 16 toward the mounting position, the contact 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 Figure 18, the first projection 803 of the contact piece 80 is located at the rear portion 241c of the contact piece rail 242, and the second projection 804 is located in the middle portion 241b (through hole 24C) of the contact piece rail 242.

[0120] As the contact piece 80 moves, the first pivot link 81 moves backward while rotating in a direction that further reduces its angle of inclination with respect to the horizontal. As the first pivot link 81 rotates and moves, the linear link 82 moves linearly further backward. As the linear link 82 moves, the second pivot link 83 rotates further in a direction that moves the engagement pin 832a backward. As the second pivot link 83 rotates, the third pivot link 84 rotates further in a direction that moves the engagement pin 842 forward.

[0121] As shown in Figure 6(b), when the third pivot link 84 rotates, the coil spring 86 rotates along with the rotation of the third pivot link 84, and the second arm portion 862 of the coil spring 86 engages with the engagement pin 854 of the shutter link 85 from below. When the second arm portion 862 engages with the engagement pin 854, the shutter link 85 rotates in a direction that moves the engagement portion 853 upward, and the shutter 64 moves from the closed position to the open position.

[0122] In this case, as the linear link 82 moves backward, the contact portion 912 of the arm 91 in the lock 9 moves down the first inclined surface 823a of the link projection 823 of the linear link 82 due to the biasing force of the lock spring 92, and is positioned on the front side of the link projection 823. With the contact portion 912 positioned on the front side of the link projection 823, the contact portion 912 and the second inclined surface 823b are locked together, restricting the forward movement of the linear link 82.

[0123] As a result, with the connecting link 8 moving the shutter 64 to the open position, the linear link 82 is fixed by the lock 9, preventing the shutter 64 from unintentionally moving from the open position to the closed position. In other words, the lock 9 restricts the movement of the linear link 82 by engaging the contact portion 912 located in front of the link projection 823 with the link projection 823, thereby stably holding the shutter 64 in the open position.

[0124] Furthermore, in lock 9, as the contact portion 912 of the arm 91 transitions from a state where it is positioned behind the link projection 823 and the connecting link 8 moves the shutter 64 to the open position, to a state where it is positioned in front of the link projection 823 and the connecting link 8 moves the shutter 64 to the open position, the contact portion 912 rides up onto the top of the link projection 823, and the pressing load of the lock spring 92 on the linear link 82 becomes maximum.

[0125] As the process cartridge 50 is further inserted from the position shown in Figure 18 toward the mounting position, the drum shaft 54a moves from the middle 241b to the rear 241c of the cartridge rail 241, and then moves within the rear 241c toward the mounting direction. Meanwhile, the contact piece 80 remains in the position where the first projection 803 is at the rear 241c of the contact piece rail 242, and the contact piece 80 and the drum shaft 54a move apart. Subsequently, the process cartridge 50 reaches the mounting position as shown in Figure 19 and becomes mounted on the main body 2 of the apparatus.

[0126] Thus, the process cartridge 50 is movable from an installation start position in which the tip 50A in the installation direction is inserted into the device body 2, to an installation position in which it is installed in the device body 2. During the process of the process cartridge 50 moving from the installation start position to the installation position, the contact piece 80 comes into contact with the drum shaft 54a of the process cartridge 50 and moves, causing the shutter 64 to move from the closed position to the open position. Furthermore, when the process cartridge 50 is in the installation position after the shutter 64 has moved to the open position, the process cartridge 50 and the contact piece 80 are separated.

[0127] If the process cartridge 50 in the mounting position were in contact with the contact piece 80 of the connecting link 8 connected to the shutter 64, there is a risk that unwanted force would be applied to the process cartridge 50 from the contact piece 80 when an opening or closing force is applied to the shutter 64. However, since the process cartridge 50 in the mounting position and the contact piece 80 are spaced apart, no unwanted force is applied to the process cartridge 50 mounted on the device body 2 from the contact piece 80, and it is possible to suppress the connecting link 8 from adversely affecting the printing accuracy.

[0128] Furthermore, in the image forming apparatus 1, as the process cartridge 50 moves from the mounting start position to the mounting position, the contact piece 80 comes into contact with the process cartridge 50 and moves, and when the shutter 64 is in the open position, the lock 9 fixes the connecting link 8, and the process cartridge 50 moves away from the contact piece 80 downstream of the position of the process cartridge 50 when the lock 9 fixes the connecting link 8 in the insertion direction.

[0129] In this way, when the process cartridge 50 is located downstream of the position where the shutter 64 moves to the open position and the lock 9 fixes the connecting link 8, the process cartridge 50 and the contact piece 80 are separated. As a result, no unnecessary force is applied to the process cartridge 50 from the contact piece 80, and the connecting link 8 is prevented from adversely affecting the printing accuracy.

[0130] Furthermore, in the image forming apparatus 1, the connecting link 8 has a linear link 82, and the movement of the contact piece 80 guided by the contact piece rail 242 is converted into a linear movement in the front-rear direction by the linear link 82. Therefore, even if there is a distance between the process cartridge 50 mounted on the apparatus body 2 from the front and the fuser 6 located at the rear of the apparatus body 2, it is possible to efficiently transmit driving force from the contact piece 80 to the shutter 64.

[0131] Furthermore, since the driving force is transmitted from the linear-moving link 82 to the shutter 64 via the second and third rotating links 83 and 84 that perform rotational movements, the space required in the front-to-back direction when transmitting the driving force to the shutter 64 can be reduced, making it possible to miniaturize the main body of the device 2.

[0132] Furthermore, in the image forming apparatus 1, when the process cartridge 50 is mounted on the apparatus body 2, the drum shaft 54a protruding towards the first main frame 24 contacts the contact piece 80 of the connecting frame 8 via the through hole 24C. This eliminates the need to separately provide a guide projection on the process cartridge 50 to enter the through hole 24C and move the contact piece 80, thus simplifying the configuration of the process cartridge 50.

[0133] (Action taken when the process cartridge is removed) Next, the operation of the connecting link 8 when detaching the process cartridge 50 from the main body 2 of the device will be described. When detaching the process cartridge 50, the connecting link 8 operates in the opposite direction to when installing the process cartridge 50.

[0134] When the process cartridge 50, which is in the mounting position shown in Figure 19, is detached from the main body 2 of the apparatus toward the front, the drum shaft 54a moves downstream in the rear part 241c of the cartridge rail 241 in the direction of detachment. The detachment direction is the direction in which the process cartridge 50, when removed from the mounting body 2, moves toward the outside of the mounting body 2. As shown in Figure 18, when the drum shaft 54a moving within the cartridge rail 241 reaches the middle part 241b (through hole 24C), the drum shaft 54a comes into contact with the second projection 804 of the contact piece 80.

[0135] As shown in Figure 16, the contact piece 80, which is in contact with the drum shaft 54a, is pressed by the drum shaft 54a and moves downstream in the direction of departure of the process cartridge 50. In other words, the contact piece 80 moves from the position where the first projection 803 is at the rear 242c of the contact piece rail 242 to the position where it is at the middle 242b (through hole 24C).

[0136] As the contact piece 80 moves, the first pivot link 81 moves forward while rotating in a direction that increases its inclination angle with respect to the horizontal, and the linear link 82 moves linearly forward. As the linear link 82 moves, the connecting hole 822 of the linear link 82 engages with the engagement pin 832a of the second pivot link 83, causing the second pivot link 83 to rotate in a direction that moves the engagement pin 832a forward. As the second pivot link 83 rotates, the connecting hole 833a of the second pivot link 83 engages with the engagement pin 842 of the third pivot link 84, causing the third pivot link 84 to rotate in a direction that moves the engagement pin 842 backward.

[0137] As the process cartridge 50 is further detached from the main body 2, the contact piece 80 is moved further downstream in the detachment direction by the drum shaft 54a, which moves within the middle portion 241b (through hole 24C) of the cartridge rail 241. As shown in Figure 14, when the contact piece 80 moves until the second projection 804 is positioned at the front portion 242a of the contact piece rail 242, the shutter link 85 rotates via the connecting link 8 in a direction that moves the engaging portion 853 downward, as shown in Figure 6(a).

[0138] Specifically, the movement of the contact piece 80 causes the third pivot link 84 to rotate further in the direction that the engagement pin 842 moves backward. As the third pivot link 84 rotates, the coil spring 86 rotates along with the rotation of the third pivot link 84, and the first arm portion 861 of the coil spring 86 engages with the engagement pin 854 of the shutter link 85 from above. The engagement of the first arm portion 861 with the engagement pin 854 causes the shutter link 85 to rotate in the direction that the engagement portion 853 moves downward. As a result, the shutter 64 moves from the closed position to the open position.

[0139] Thus, in the image forming apparatus 1, when the process cartridge 50 is mounted to the apparatus body 2, the drum shaft 54a contacts the first projection 803 of the contact piece 80, causing the connecting link 8 to move the shutter 64 from the closed position to the open position. When the process cartridge 50 is detached from the apparatus body 2, the drum shaft 54a contacts the second projection 804 of the contact piece 80, causing the connecting link 8 to move the shutter 64 from the open position to the closed position. With this configuration, it is possible to operate the connecting link 8 both when mounting and detaching the process cartridge 50 with a simple configuration.

[0140] [Process cartridge pressure spring] As shown in Figure 20, the apparatus body 2 is equipped with a pressure spring 95 that contacts the drum shaft 54a and presses the process cartridge 50 into the mounting position. The pressure spring 95 is supported by the first main body frame 24. The pressure spring 95 has a support portion 951 supported by the first main body frame 24 and an arm portion 952 extending from the support portion 951.

[0141] A portion of the arm 952 enters the rear 241c of the cartridge rail 241. The arm 952 is movable between a first position (shown by a dashed line in Figure 20(a)) when the drum shaft 54a is not in contact with it, a second position (shown by a dashed line in Figure 20(a)) when the drum shaft 54a is in contact with it and retracted from the rear 241c before the process cartridge 50 to be mounted on the device body 2 reaches the mounting position, and a third position (shown by a solid line in Figure 20(b)) when it is in contact with the drum shaft 54a of the process cartridge 50 located at the mounting position.

[0142] As shown in Figure 20(a), the arm portion 952 of the compression spring 95 is in a first position when it is not in contact with the drum shaft 54a, which is moving in the mounting direction within the rear portion 241c of the cartridge rail 241. When the drum shaft 54a, which is moving in the mounting direction within the rear portion 241c, comes into contact with the arm portion 952, the arm portion 952 is pressed by the drum shaft 54a and moves downward.

[0143] The arm portion 952, having moved below the first position, has a biasing force that presses the drum shaft 54a upward. The biasing force of the arm portion 952, which has moved downward due to being pressed by the drum shaft 54a, increases as the amount of downward movement increases, and reaches its maximum when it moves to the second position, which is retracted from the rear portion 241c.

[0144] After the arm 952 moves to the second position, when the drum shaft 54a moves in the mounting direction and reaches the mounting position, the arm 952 moves above the second position to the third position. The arm 952 in the third position presses against the drum shaft 54a with a smaller biasing force than when it is in the second position. The process cartridge 50 is pressed into the mounting position when the arm 952 in the second position comes into contact with the drum shaft 54a.

[0145] In this way, the arm portion 952 of the compression spring 95 comes into contact with the drum shaft 54a as the process cartridge 50 moves from a position upstream of the insertion position to the mounting position, and moves to a second position where the pressing load on the process cartridge 50 is maximum.

[0146] When the arm 952 moves to the second position, the position of the process cartridge 50 is such that the drum shaft 54a is located at the rear 241c of the cartridge rail 241. Also, when the pressing load of the lock spring 92 on the linear link 82 is maximum, the position of the process cartridge 50 is such that the drum shaft 54a is located at the middle 241b (through hole 24C) of the cartridge rail 241.

[0147] In other words, the position of the process cartridge 50 when the pressing load of the lock spring 92 is at its maximum is upstream in the insertion direction from the position of the process cartridge 50 when the pressing load of the pressing spring 95 is at its maximum. Therefore, when attaching or detaching the process cartridge 50 from the device body 2, the timing of when the pressing load of the pressing spring 95 is at its maximum and the timing of when the pressing load of the lock spring 92 is at its maximum are different, which helps to suppress an increase in the operating load of the process cartridge 50.

[0148] [Pinch roller spring] As shown in Figure 21, the apparatus body 2 is equipped with a roller spring 96 that presses the pinch roller 35b when the process cartridge 50 is in the mounting position. The roller spring 96 is supported by the first main frame 24. The roller spring 96 has a support portion 961 supported by the first main frame 24 and an arm portion 962 extending from the support portion 961.

[0149] The arm portion 962 is movable between a fourth position (shown by a dashed line in Figure 21) when the pinch roller 35b is not in contact with it, and a fifth position (shown by a solid line in Figure 21) when it is in contact with the pinch roller 35b of the process cartridge 50 located in the mounting position.

[0150] The arm portion 962 of the roller spring 96 is in the fourth position when the pinch roller 35b is not in contact with the arm portion 962 (see the pinch roller shown by the dashed line in Figure 21). When the process cartridge 50 is inserted into the apparatus body 2 from the state in which the pinch roller 35b is not in contact with the arm portion 962, the pinch roller 35b comes into contact with the arm portion 962, and the arm portion 962 moves upward. Subsequently, the process cartridge 50 reaches the mounting position while maintaining the state in which the pinch roller 35b is in contact with the arm portion 962.

[0151] When the process cartridge 50 is in the mounting position, the arm portion 962 is pressed by the pinch roller 35b (see the pinch roller shown by the solid line in Figure 21) and moves to a fifth position above the fourth position.

[0152] The arm 962, having moved above the fourth position, has a biasing force that presses the pinch roller 35b downward. The biasing force of the arm 952, which has moved upward due to being pressed by the pinch roller 35b, increases as the amount of upward movement increases. The amount of upward movement of the arm 962 increases from the time the pinch roller 35b begins to make contact until the process cartridge 50 reaches the mounting position, and the amount of upward movement is maximum when the process cartridge 50 reaches the mounting position. Therefore, the biasing force of the arm 952 is maximum when the process cartridge 50 is in the mounting position.

[0153] In this way, the arm portion 962 of the roller spring 96 comes into contact with the pinch roller 35b as the process cartridge 50 moves from a position upstream of the mounting position in the insertion direction to the mounting position, and moves to a fifth position where the pressing load on the pinch roller 35b is maximum.

[0154] The position of the process cartridge 50 when the arm 962 moves to the fifth position is the mounting position. Also, the position of the process cartridge 50 when the pressing load of the lock spring 92 on the linear link 82 is maximum is when the drum shaft 54a is located in the middle part 241b (through hole 24C) of the cartridge rail 241.

[0155] In other words, the position of the process cartridge 50 when the pressing load of the lock spring 92 is at its maximum is upstream in the insertion direction from the position of the process cartridge 50 when the pressing load of the roller spring 96 is at its maximum. Therefore, when attaching or detaching the process cartridge 50 from the device body 2, the timing of when the pressing load of the roller spring 96 is at its maximum and the timing of when the pressing load of the lock spring 92 is at its maximum are different, which helps to suppress an increase in the operating load of the process cartridge 50.

[0156] In this embodiment, when the process cartridge 50 is in the mounting position, the pressure spring 95 and the roller spring 96 of the pinch roller 35b act on the process cartridge 50. However, these may be absent, or a different mechanism may act on the process cartridge 50. [Explanation of Symbols]

[0157] 1. Image forming apparatus 2. Main unit of the device 6. Fuser 8 Linking Links 9 Rock 24. First main frame 24A Front Frame 24C through hole 50 Process Cartridges 53 Developing roller 54 Photosensitive drum 54a Drum shaft 61 Heating Unit 63 Fixing Frame 63a 1st opening 64 shutters 80 Contact piece 81. First Dynamic Link 82 Linear link 83. Second Dynamic Link 84. 3rd Dynamic Link 85 Shutterlink 91 Arm 92 Lock spring 241 Cartridge Rail 242 Contact rail 803 1st protrusion 804 2nd protrusion 823 Link protrusion 912 Contact part S Seat X-axis center

Claims

1. The main body of the device, A cartridge having guide protrusions is detachably mounted on the main body of the device and includes at least one of a photosensitive drum, a developing roller, and a toner container. An image forming apparatus comprising a fuser for fixing a toner image transferred to a conveyed sheet, the fuser having a heater, a fixing frame covering the heater and having an opening formed on the upstream side of the heater in the sheet conveying direction, and a shutter that moves between a closed position that closes the opening and an open position that opens the opening, The main body of the aforementioned device is When the cartridge is attached to the main body of the device, a guide frame guides the guide projection, A connecting link is provided, which is connected to the shutter and moves the shutter from the closed position to the open position when the cartridge is mounted on the device body, and moves the shutter from the open position to the closed position when the cartridge is detached from the device body. Equipped with, The guide frame has through holes, The guide projection enters the through hole when the cartridge is mounted on the device body. The connecting link is located on the opposite side of the cartridge mounted on the device body relative to the guide frame, and contacts the guide projection of the cartridge mounted on the device body through the through hole. The image forming apparatus is characterized in that the apparatus body has a lock that restricts the movement of the connecting link that moves the shutter to the open position or the closed position.

2. The aforementioned connecting link is A contact piece that contacts the aforementioned guide projection, A first rotating link is connected to the aforementioned contact piece and rotates along with the movement of the aforementioned contact piece, The image forming apparatus according to claim 1, further comprising a linear link connected to the first rotating link and moving linearly along the rotation of the first rotating link.

3. The image forming apparatus according to claim 2, wherein the lock restricts the movement of the linear link by pressing the linear link.

4. The linear link has a link projection that protrudes toward the locking side, The lock comprises an arm and a spring that biases the tip of the arm toward the linear link side. The image forming apparatus according to claim 3, wherein the tip of the arm overcomes the link projection as the linear link moves and is positioned on one or the other side of the link projection in the direction of movement of the linear link.

5. The contact piece has a first projection and a second projection located upstream of the first projection in the cartridge mounting direction, The first projection contacts the guide projection of the cartridge which is mounted on the main body of the device, The image forming apparatus according to any one of claims 2 to 4, wherein the second projection abuts against the guide projection of the cartridge that is detached from the main body of the apparatus.

6. The guide frame has a cartridge rail that guides the guide projection of the cartridge and a contact piece rail that guides the contact piece, The cartridge rail and the contact rail overlap in some parts. The image forming apparatus according to any one of claims 3 to 5, wherein the overlapping portion of the cartridge rail and the contact piece rail is the through hole.

7. The aforementioned cartridge has a photosensitive drum, The image forming apparatus according to any one of claims 1 to 6, wherein the guide projection is a metal drum shaft protruding in the axial direction of the photosensitive drum.

8. The aforementioned connecting link is A second rotating link is connected to the linear link and rotates along the movement of the linear link, A third rotating link is connected to the second rotating link and rotates along with the rotation of the second rotating link, An image forming apparatus according to any one of claims 2 to 6, further comprising: a shutter link connected to the third pivot link, which moves along the rotation of the third pivot link to move the shutter between an open position and a closed position.

9. The main body of the device, A cartridge having guide protrusions is detachably mounted on the main body of the device and includes at least one of a photosensitive drum, a developing roller, and a toner container. An image forming apparatus comprising a fuser for fixing a toner image transferred to a conveyed sheet, the fuser having a heater, a fixing frame covering the heater and having an opening formed on the upstream side of the heater in the sheet conveying direction, and a shutter that moves between a closed position that closes the opening and an open position that opens the opening, The main body of the aforementioned device is When the cartridge is attached to the main body of the device, a guide frame guides the guide projection, A connecting link is provided, which is connected to the shutter and moves the shutter from the closed position to the open position when the cartridge is mounted on the device body, and moves the shutter from the open position to the closed position when the cartridge is detached from the device body. Equipped with, The guide frame has through holes, The guide projection enters the through hole when the cartridge is mounted on the device body. The aforementioned connecting link is It is located on the opposite side of the cartridge mounted on the device body with respect to the guide frame, and contacts the guide projection of the cartridge mounted on the device body through the through hole, A contact piece that contacts the aforementioned guide projection, A first rotating link is connected to the aforementioned contact piece and rotates along with the movement of the aforementioned contact piece, An image forming apparatus characterized by having a linear link connected to the first rotating link and moving linearly along the rotation of the first rotating link.

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