Image forming apparatus

Abstract

To provide an image forming apparatus equipped with a fixing device capable of easily removing paper jammed in a fixing nip when a shutter is closed.SOLUTION: An image forming device is provided with a fixing device which is supported in a device main body and is provided with a heating rotary body and a pressurizing rotary body which form a fixing nip for fixing a toner image on a sheet; a shutter (65) which can rotate in a closed posture in which the heating rotary body is covered and in an open posture in which the heating rotary body is exposed; a mounting member which is detachably mounted to the device main body; and a projection which is provided on the mounting member and rotates the shutter (65) from the closed posture to the open posture when the mounting member is mounted to the device main body, wherein the shutter (65) is provided with a main body section (101) which is pressed by the projection, and a movable section (103) which rotates integrally with the main body section (101) and can rotate in the direction of pulling out the mounting member with respect to the main body section (101).SELECTED DRAWING: Figure 6

Description

[Technical Field]

[0001] The present invention relates to an image forming apparatus equipped with a fixing device having a shutter that covers a heating rotor. [Background technology]

[0002] The fixing device includes a heating rotor and a pressure rotor that form a fixing nip. Such fixing devices may be provided with a shutter that can be moved between a closed position that covers the heating rotor and an open position that exposes the heating rotor. When removing paper jammed in the fixing nip, the shutter moves to the closed position to prevent the user from touching the heating rotor. On the other hand, during the fixing operation, the shutter moves to the open position.

[0003] Patent Document 1 describes an image forming apparatus that includes a cartridge that is removably mounted in the apparatus main body, and that moves a shutter from a closed position to an open position when the cartridge is mounted in the apparatus main body. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2019-101165 A Summary of the Invention [Problem to be solved by the invention]

[0005] In an image forming apparatus such as that described in Patent Document 1, if a paper jam occurs in the fixing nip, the paper must be removed from the fixing nip with the shutter closed. If the paper comes into contact with the closed shutter at this time, a large force may be required to pull the paper out, or the paper may be torn.

[0006] SUMMARY OF THE INVENTION In consideration of the above circumstances, an object of the present invention is to provide an image forming apparatus equipped with a fixing device that can easily remove paper jammed in the fixing nip when the shutter is closed. [Means for solving the problem]

[0007] In order to achieve the above object, the image forming apparatus of the present invention comprises a fixing device supported within the apparatus main body and including a heating rotor and a pressure rotor that form a fixing nip for fixing a toner image to paper, a shutter that can rotate to a closed position that covers the heating rotor and an open position that exposes the heating rotor, a mounting member that is removably attached to the apparatus main body, and a protrusion that is provided on the mounting member and rotates the shutter from the closed position to the open position when the mounting member is attached to the apparatus main body, and the shutter is characterized by comprising a main body portion that is pressed by the protrusion, and a movable portion that rotates integrally with the main body portion and can rotate relative to the main body portion in the direction of pulling out the mounting member.

[0008] In the present invention, the movable portion may be made rotatable relative to the main body portion by being pushed up.

[0009] In the present invention, the movable portion may include a roller that contacts and guides the paper being removed from the fixing nip along the pull-out direction when the shutter is rotated to the closed position.

[0010] In the present invention, the device may be characterized by comprising an elastic member that supports the roller on the movable part so that it can move up and down, and a latch part that connects the movable part to the main body part via the roller so that it can rotate integrally with the main body part, and by pushing up the roller, the connection between the movable part and the main body part by the latch part is released, and the movable part becomes rotatable relative to the main body part.

[0011] The present invention may be characterized by further comprising a biasing member that biases the shutter toward the closed position.

[0012] In the present invention, the mounting member may be a drum unit including a photosensitive drum and a housing that accommodates the photosensitive drum, and the protrusion may be provided on the housing. [Effects of the Invention]

[0013] According to the present invention, if the shutter interferes with the paper when removing paper jammed in the fixing nip, the movable part of the shutter rotates automatically, so that the paper can be removed without receiving resistance from the shutter. [Brief explanation of the drawings]

[0014] [Figure 1] 1 is a front view schematically illustrating an internal structure of an image forming apparatus according to an embodiment of the present invention. [Figure 2] 1 is a perspective view showing a drum unit in an image forming apparatus according to an embodiment of the present invention; [Figure 3] 2 is a cross-sectional view showing the fixing device (in a state where the shutter is rotated to a closed position) in the image forming apparatus according to one embodiment of the present invention. FIG. [Figure 4] 2 is a cross-sectional view showing the fixing device (in a state where the shutter is rotated to an open position) in the image forming apparatus according to one embodiment of the present invention. FIG. [Figure 5] 1 is a perspective view showing a shutter (in a state where a movable part is not rotated) in an image forming apparatus according to an embodiment of the present invention. [Figure 6] 1 is a perspective view showing a shutter (in a state where a movable part is rotated) in an image forming apparatus according to an embodiment of the present invention. [Figure 7] 1 is a perspective view showing a part of a roller assembly of a shutter (in a state where a movable part is not rotating) in an image forming apparatus according to one embodiment of the present invention. FIG. [Figure 8] 1 is a perspective view showing a part of a roller assembly of a shutter (in a state where a movable part is rotated) in an image forming apparatus according to one embodiment of the present invention. FIG. [Figure 9] 1 is a cross-sectional view showing a shutter (in a state where a movable part is not rotating) in an image forming apparatus according to an embodiment of the present invention. [Figure 10] 1 is a cross-sectional view showing a shutter (in a state where a movable portion is pushed up) in an image forming apparatus according to an embodiment of the present invention. [Figure 11] 1 is a cross-sectional view showing a shutter (in a state where a movable part is rotated) in an image forming apparatus according to an embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0015] An image forming apparatus according to an embodiment of the present invention will be described below with reference to the drawings.

[0016] First, the overall configuration of the image forming apparatus 1 will be described using Fig. 1. Fig. 1 is a front view that schematically shows the internal configuration of the image forming apparatus 1. The symbols Fr, Rr, L, and R used in the following drawings represent front, rear, left, and right, respectively.

[0017] The device body 3 of the image forming device 1 is provided with a paper feed cassette 5 that stores paper, a paper feed device 7 that feeds paper from the paper feed cassette 5, an image forming unit 9 that forms a toner image on paper by electrophotography, a fixing device 11 that fixes the toner image on the paper, a discharge device 13 that discharges paper, and a paper discharge tray 15 on which the discharged paper is stacked. Furthermore, the device body 3 is formed with a transport path 17 along which paper is transported from the paper feed device 7 through the image forming unit 9 and the fixing device 11 toward the discharge device 13 in a transport direction.

[0018] Next, the image forming unit 9 will be further described. The image forming unit 9 is made up of a drum unit 21, a developing unit 23, an exposure device 25, a toner container 27, and a transfer roller 29. The drum unit 21, the developing unit 23, and the toner container 27 are removably attached to the apparatus main body 3. The exposure device 25 and the transfer roller 29 are fixed to the apparatus main body 3.

[0019] First, the drum unit 21 will be described with reference to FIGS. 2 and 1. FIG. 2 is a perspective view showing the drum unit 21. The drum unit 21 includes a photosensitive drum 31, a charging device 33, a cleaning device 35, and a drum housing 37 that supports these. The photosensitive drum 31 is rotatably supported by the drum housing 37. A portion of the outer circumferential surface of the photosensitive drum 31 is exposed through an opening formed in the drum housing 37. The charging device 33 and the cleaning device 35 are arranged around the photosensitive drum 31 along the rotation direction of the photosensitive drum 31.

[0020] The drum unit 21 is removably mounted at a predetermined position upstream of the fixing device 11 in the transport direction through an opening 3a formed in the front surface of the device body 3. More specifically, as shown in FIG. 1, rails 3b are formed on the left and right side plates of the device body 3, extending from the opening 3a toward a predetermined position. Also, as shown in FIG. 2, guide pins 39 are provided on the left and right side plates of the drum housing 37. The drum unit 21 is positioned at a predetermined position by engaging these guide pins 39 with the rails 3b and moving the drum unit 21 along the rails 3b. The drum unit 21 is an example of a mounting member removably mounted to the device body 3 in the present invention.

[0021] 2, the drum housing 37 is provided with a protrusion 41. The protrusion 41 protrudes from the rear surface (the surface on the downstream side in the conveying direction) of the drum housing 37 toward the rear (the downstream side in the mounting direction), that is, toward the fixing device 11. The protrusion 41 has a substantially triangular plate shape when viewed from the left and right.

[0022] Next, the developing unit 23 will be described. As shown in Fig. 1, the developing unit 23 includes an agitating roller 51, a supply roller 53, a developing roller 55, and a developing housing 57 that supports these rollers and contains the developer. Each roller is rotatably supported by the developing housing 57. A portion of the outer circumferential surface of the developing roller 55 is exposed through an opening formed in the developing housing 57.

[0023] The developing unit 23 is removably mounted at a predetermined position upstream of the drum unit 21 in the transport direction through the opening 3a of the device main body 3. Guide pins (not shown) are provided on the left and right side plates of the developing housing 57. The developing unit 23 is positioned at a predetermined position by engaging these guide pins with the rails 3b and moving the developing unit 23 along the rails 3b. When the developing unit 23 is positioned, a portion of the outer circumferential surface of the developing roller 55 exposed from the opening of the developing housing 57 faces, with a predetermined gap between them, a portion of the outer circumferential surface of the photosensitive drum 31 exposed from the opening of the drum housing 37 of the drum unit 21.

[0024] Next, we will explain the exposure device 25. The exposure device 25 is disposed above the drum unit 21 and the developing unit 23. The exposure device 25 irradiates the outer peripheral surface of the photosensitive drum 31 with laser light based on image data, thereby forming an electrostatic latent image on the photosensitive drum 31.

[0025] Next, a description will be given of the toner container 27. The toner container 27 is disposed above the developing unit 23. The toner container 27 can communicate with the developing housing 57 of the developing unit 23, and supplies toner to the developing housing 57.

[0026] Next, we will explain the transfer roller 29. The transfer roller 29 is arranged to face the photosensitive drum 31 exposed from the opening of the drum housing 37 of the drum unit 21, across the transport path 17. A transfer nip is formed between the transfer roller 29 and the photosensitive drum 31.

[0027] Next, a brief description of the image forming operation will be given. Paper fed from the paper feed cassette 5 by the paper feed device 7 is transported to the image forming unit 9 along the transport path 17. In the image forming unit 9, a toner image is formed on the paper. Specifically, in the drum unit 21, the photosensitive drum 31 is charged to a predetermined potential by the charging device 33. Then, the exposure device 25 irradiates the photosensitive drum 31 with laser light based on image data, forming an electrostatic latent image on the photosensitive drum 31. In the development unit 23, toner supplied from the toner container 27 is stirred and charged with the developer housed in the development housing 57 by the stirring roller 51. The charged toner is then supplied to the development roller 55 by the supply roller 53 and held on the development roller 55. The held toner is supplied to the electrostatic latent image formed on the photosensitive drum 31, and the electrostatic latent image is developed into a toner image. The toner image is transferred from the photosensitive drum to the paper at the transfer nip. The toner remaining on the photosensitive drum is removed by a cleaning device 35 .

[0028] The paper on which the toner image has been formed is transported along transport path 17 to fixing device 11, where the toner image is fixed to the paper. The paper on which the toner image has been fixed is discharged onto paper output tray 15 by discharge device 13.

[0029] Next, the fixing device 11 will be further described with reference to Figures 3 and 4. Figures 3 and 4 are cross-sectional views showing the fixing device 11.

[0030] The fixing device 11 includes a belt assembly 61, a pressure roller 63, a shutter 65, and a fixing housing 67 that supports these components.

[0031] First, a description will be given of the belt assembly 61. The belt assembly 61 includes a fixing belt 71, a support member 73 that supports the fixing belt 71, and a heater 75 that is supported by the support member 73 and heats the fixing belt 71.

[0032] First, the fixing belt 71 will be described. The fixing belt 71 is an endless belt having a predetermined inner diameter and a width greater than the width of the paper. The fixing belt 71 is made of a flexible material and has a base layer, an elastic layer provided on the outer surface of the base layer, and a release layer provided on the outer surface of the elastic layer. The base layer is made of resin. The elastic layer is made of silicone rubber or the like. The release layer is made of PFA tubing or the like. The fixing belt is an example of a heating rotator of the present invention.

[0033] The support member 73 has a sliding surface that faces the inner circumferential surface of the fixing belt 71. The sliding surface has a width wider than the width of the fixing belt 71 and is formed to follow the circumferential direction of the fixing belt 71. The support member 73 is supported by a stay 77 that passes through the hollow portion of the fixing belt 71. Both end portions of the stay 77 are fixed to a pair of end holders 79. The support member 73 is fixed to the lower surface of the stay 77, and the sliding surface faces the inner circumferential surface of the fixing belt 71.

[0034] The heater 75 is, for example, a plate-shaped ceramic heater that generates heat when electricity is applied. The heating area of ​​the heater 75 is slightly wider than the width of the paper. The heater 75 is housed in a groove formed in the sliding surface of the support member 73.

[0035] Next, a description will be given of the pressure roller 63. The pressure roller 63 has a rotating shaft, an elastic layer provided on the outer peripheral surface of the rotating shaft, and a release layer provided on the outer peripheral surface of the elastic layer.

[0036] The left and right ends of the rotation shaft of the pressure roller 63 are rotatably supported by the left and right side plates of the fixing housing 67. End holders 79 of the belt assembly 61 are supported by the left and right side plates of the fixing housing 67 above the pressure roller 63. This forms a fixing nip N between the fixing belt 71 of the belt assembly 61 and the pressure roller. A drive gear (not shown) is fixed to one end of the rotation shaft of the pressure roller 63. The drive gear is connected to a motor (not shown) via a gear train (not shown).

[0037] When the motor is driven, the drive gear rotates in the clockwise direction in Figures 3 and 4 via a gear train. This rotation of the drive gear causes the pressure roller 63 to rotate in one direction (clockwise in this example), and the fixing belt 71, which is in contact with the pressure roller 63 at the fixing nip N, to rotate in the other direction (counterclockwise in this example). As a result, the paper guided to the fixing nip N passes through the fixing nip N. At this time, the toner image is heated and pressurized and fixed to the paper.

[0038] Next, the shutter 65 will be described with reference to Figures 5 to 9. Figures 5 and 6 are perspective views showing the shutter 65, Figures 7 and 8 are perspective views showing the roller assembly 85, and Figure 9 is a cross-sectional view showing the roller assembly 85.

[0039] The shutter 65 includes a rotating shaft 81 , a shutter plate 83 provided integrally with the rotating shaft 81 , and two roller assemblies 85 supported by the shutter plate 83 .

[0040] First, the rotating shaft 81 will be described. As shown in Figures 5 and 6, the rotating shaft 81 has a length longer than the width of the fixing belt 71. A protruding piece 91 that protrudes upward is formed in the center of the rotating shaft 81. The protruding piece 91 is inclined toward the drum unit 21 side (front side).

[0041] Next, we will explain the shutter plate 83. The shutter plate 83 has a rectangular shape with the same width as the fixing belt 71 and a predetermined height, and has a main body part 101 provided integrally with the rotary shaft 81, and a movable part 103 supported rotatably relative to the main body part 101.

[0042] The main body 101 has an upper end 111 arranged along the pivot shaft 81 and left and right end portions 113 arranged at both ends of the upper end 111. A rectangular space elongated in the axial direction of the pivot shaft 81 is formed between the upper end 111 and the left and right end portions 113. The width of the space is longer than the width of the paper. Two rectangular openings 115 elongated in the axial direction of the pivot shaft 81 are formed in the upper end 111 with a predetermined distance in the axial direction. The lower portion of the opening 115 is referred to as a lower opening portion 117 (see FIGS. 7 and 8). As shown in FIG. 9, the lower opening portion 117 has a rectangular cross-sectional shape elongated in the vertical direction, and the front and rear surfaces are parallel flat surfaces. As shown in FIGS. 5 and 6, left and right shaft portions 119 parallel to the pivot shaft 81 are formed at the upper ends of the inner surfaces (facing each other) of the left and right end portions 113.

[0043] The movable part 103 has a rectangular plate shape and is placed in the space formed between the upper end 111 and the left and right end parts 113 of the main body part 101. The movable part 103 has rectangular notches 121 cut upward from the lower edge. The notches 121 are formed below the two openings 115 of the main body part 101 (upper end part 111), respectively. As shown in FIGS. 7 and 8, the rear surface of the movable part 103 has horizontally protruding protrusions 123 formed on both sides above the notches 121.

[0044] As shown in FIGS. 5 and 6, the upper ends of the left and right side surfaces of movable part 103 are rotatably supported by left and right shafts 119 formed on the inner surfaces of left and right ends 113 of main body part 101. A coil portion of a torsion coil spring 125 is fitted onto each of left and right shafts 119. One arm of torsion coil spring 125 is fixed to main body part 101, and the other arm is fixed to movable part 103. Torsion coil spring 125 supports movable part 103 so that it is accommodated in the space of main body part 101 (see FIG. 5). When movable part 103 is pushed forward relative to main body part 101, movable part 103 rotates forward about shaft 119 against the biasing force of torsion coil spring 125 (see FIG. 6).

[0045] Next, roller assembly 85 will be described mainly with reference to Figures 7, 8, and 9. Roller assembly 85 has a roller 131 and a holder 133 that rotatably supports roller 131. Holder 133 is rectangular and elongated in the vertical direction, and has a lower part 141 and an upper part 143.

[0046] The lower portion 141 has a rectangular notch 145 cut upward from the lower edge. Left and right shaft portions 147 parallel to the axial direction of the rotation shaft 81 are formed at the lower end portions of both side surfaces of the notch 145. The roller 131 is housed in this notch 145 and is rotatably supported by the shaft portions 147. The lower portion 141 also has a front protrusion 149 and a rear protrusion 151 formed therein, spaced apart in the thickness direction by the thickness of the movable portion 103. The front protrusions 149 extend in opposite directions from both side surfaces of the lower portion 141. The rear protrusions 151 protrude in opposite directions from the lower end portions of both side surfaces of the lower portion 141.

[0047] Upper portion 143 extends upward from the rear end of the upper surface of lower portion 141. As shown in FIG. 9, a hook portion 153 that bends forward is formed at the upper end of upper portion 143. Hook portion 153 has a first bent portion 153a that bends forward at a substantially right angle from the upper end of upper portion 143, and a second bent portion 153b that bends downward at a substantially right angle from the tip of first bent portion 153a. The cross-sectional shape of the space surrounded by the upper end of upper portion 143 and hook portion 153 is a rectangle that is long in the vertical direction, and the front surface of the upper end of upper portion 143 and the rear surface of second bent portion 153b are parallel planes.

[0048] The roller assembly 85 is supported by an opening 115 formed in the main body 101 (upper end 111) and a notch 121 formed in the movable part 103. Specifically, a lower part 141 of the holder 133 is housed in the notch 121 of the movable part 103. The movable part 103 is sandwiched between a front protrusion 149 and a rear protrusion 151 of the lower part 141 of the holder 133 on both sides of the notch 121. A hook part 153 of the upper part 143 of the holder 133 is inserted into the opening 115 of the main body 101 and hooked from the rear side onto a lower part 117 of the opening. In this state, the roller 131 protrudes slightly downward from the lower edge of the movable part 103. Furthermore, there is a space between the hook part 153 and the upper end surface of the opening 115, and between the lower part 141 of the holder 133 and the upper end surface of the notch 121.

[0049] A coil spring 155 is disposed between a rear projection 151 formed on the lower portion 141 of the holder 133 and a projection 123 formed on the rear surface of the movable portion 103. The coil spring 155 biases the holder 133 downward relative to the movable portion 103.

[0050] In this way, the movable part 103 is sandwiched between the front projection 149 and the rear projection 151 of the holder 133 of the roller assembly 85, so that the roller assembly 85 can rotate integrally with the movable part 103. In addition, the roller assembly 85 can move up and down relative to the movable part 103 by the coil spring 155.

[0051] 9, the opening lower portion 117 of the main body portion 101 is sandwiched between the upper end portion of the upper portion 143 of the holder 133 and the second bent portion 153b of the hook portion 153. The front surface of the upper end portion and the rear surface of the opening lower portion 117, and the rear surface of the second bent portion 153b and the front surface of the opening lower portion 117 are in surface contact with each other, so the hook portion 153 cannot rotate with respect to the opening lower portion 117. In other words, the holder 133 cannot rotate with respect to the main body portion 101, and the movable portion 103 is integrally connected to the main body portion 101 via the holder 133 (roller assembly 85) (see FIGS. 5 and 7).

[0052] On the other hand, when holder 133 is pushed up toward movable part 103, hook part 153 moves away from lower opening part 117. This allows movable part 103 to rotate relative to main body part 101 (see FIGS. 6 and 8). In this way, lower opening part 117 and hook part 153 are an example of a latch part that connects movable part 103 to main body part 101 via roller assembly 85 (roller 131) so as to rotate integrally with main body part 101.

[0053] As shown in FIGS. 3 and 4, the shutter 65 is disposed upstream of the fixing nip N in the transport direction. Both ends of the pivot shaft 81 are rotatably supported by the left and right side plates of the fixing housing 67 above the fixing nip N. This allows the shutter 65 to pivot about the pivot shaft 81 between a closed position and an open position. In the closed position (see FIG. 3), the shutter plate 83 hangs down from the pivot shaft 81 due to its own weight, blocking the transport path 17 and covering the fixing belt 71 when viewed from the upstream side in the transport direction (the drum unit 21 side). In the open position (see FIG. 4), the shutter plate 83 pivots upstream in the transport direction about the pivot shaft 81, opening the transport path 17 and exposing the fixing belt 71 when viewed from the upstream side in the transport direction.

[0054] Furthermore, the shutter 65 is biased to the closed position by a biasing member 161. The biasing member is, for example, a torsion coil spring, and is provided at one end of the rotation shaft 81. In this case, the shutter 65 can be maintained in the closed position. Therefore, even when the drum unit 21 is removed to clear a paper jam, the operator's fingers can be prevented from accidentally touching the fixing belt 71.

[0055] In the image forming apparatus 1 having the above configuration, the opening and closing operation of the shutter 65 of the fixing device 11 will be described with reference to Figures 3 to 11. Figures 10 and 11 are side cross-sectional views showing the roller assembly 85.

[0056] When drum unit 21 and developing unit 23 are removed from apparatus main body 3, fixing device 11 is exposed through opening 3a (see FIG. 1) of apparatus main body 3. However, shutter 65 rotates to a closed position to cover fixing belt 71 (see FIG. 3), preventing an operator from accidentally touching fixing belt 71.

[0057] From this state, the worker installs the drum unit 21. The worker engages the guide pin 39 of the drum housing 37 of the drum unit 21 with the rail 3b and moves the drum unit 21 along the rail 3b toward a predetermined position. The drum unit 21 moves, with the protrusion 41 (see FIG. 2) leading, toward a predetermined position, i.e., a position upstream of the fixing device 11 in the transport direction. The protrusion 41 then abuts against the front surface of the protrusion 91 of the shutter 65. When the drum unit 21 is further moved and installed in the predetermined position, the protrusion 41 pushes the protrusion 91 rearward, as shown by the two-dot chain line in FIG. 4. The shutter plate 83 then rotates from the closed position to the open position around the pivot shaft 81. This opens the transport path 17. The developing unit 23 is then installed in the predetermined position, and the image forming operation is performed.

[0058] If a paper jam occurs in the fixing nip N during image formation, the developing unit 23 is first removed, and then the drum unit 21 is removed. This causes the protrusion 41 to separate from the protrusion 91, and the shutter plate 83 rotates from the open position to the closed position due to its own weight and the biasing force of the biasing member 161, which then maintains the shutter plate 83 in the closed position (see FIG. 3). Therefore, even when the drum unit 21 is removed to clear the paper jam, the operator's fingers can be prevented from accidentally touching the fixing belt 71. After removing the drum unit 21, the paper jammed in the fixing nip N is pulled out.

[0059] The pulled-out paper S is guided by roller 131. At this time, as shown by the arrow in FIG. 10, roller 131 is pushed up by paper S. Then, holder 133 holding roller 131 moves upward relative to main body 101 against the biasing force of coil spring 155 (see FIGS. 7 and 8). This disengages hook portion 153 from opening lower portion 117, allowing movable portion 103 to rotate relative to main body 101. Then, when paper S is further pulled out, as shown in FIG. 11, the pulled-out paper S causes movable portion 103 to rotate forward (in the pulling-out direction opposite to the installation direction of drum unit 21), so that paper S can be pulled out of fixing nip N without resistance from shutter 65.

[0060] As described above, according to the image forming apparatus 1 of the present invention, if the shutter 65 interferes with the paper when removing paper jammed in the fixing nip N, only the movable part 103 of the shutter 65 automatically rotates in the direction of pulling out the paper, so that the paper can be removed without resistance from the shutter 65. Furthermore, because the paper is guided by the roller 131, resistance when pulling it out can be reduced.

[0061] When removing paper jammed in the fixing nip N, the worker generally pulls the paper upward from the fixing nip N. This pulling action pushes up the roller 131 with the paper, automatically rotating the movable part 103. The movable part 103 cannot rotate relative to the main body part 101 due to the latch part unless an upward force is applied to the roller assembly 85, so it reliably rotates integrally with the main body part 101 during normal shutter opening and closing.

[0062] In particular, when the shutter 65 is maintained in the closed position by the biasing member 161, safety is increased, but the resistance applied to the paper from the shutter 65 when removing jammed paper increases. Even in such a case, the present invention makes it possible to remove the paper without resistance while reliably covering the fixing belt 71.

[0063] Furthermore, in the present embodiment, the drum unit 21 is an example of an attachment member that is detachably attached to the apparatus main body 3, but it may also be a cover that opens and closes the opening 3a of the apparatus main body 3.

[0064] Although the present invention has been described with reference to specific embodiments, the present invention is not limited to the above embodiments, and those skilled in the art may modify the above embodiments without departing from the scope and spirit of the present invention. [Explanation of symbols]

[0065] 1. Image forming device 3. Device body 11 Fixing device 21 Drum unit (mounting part) 31 Photosensitive drum 37 Drum housing 41 protrusion 63 Pressure roller (pressure rotating body) 71 Fixing belt (heating rotor) 85 Roller assembly 101 Main body 103 Moving parts 117 Lower opening (latch part) 131 Roller 155 Coil spring (elastic member) 154 Hook part (latch part) 161 Elastic member

Claims

1. a fixing device supported within the device body and including a heating rotor and a pressure rotor that form a fixing nip for fixing a toner image onto a sheet of paper; a shutter that is rotatable between a closed position that covers the heating rotor and an open position that exposes the heating rotor; a mounting member that is mounted on the device body in a removable manner; a protrusion provided on the mounting member, the protrusion rotating the shutter from the closed position to the open position when the mounting member is mounted to the device body, The shutter is a main body portion that is pushed by the protrusion; an image forming apparatus comprising: a movable portion that rotates integrally with the main body portion and is rotatable relative to the main body portion in a direction in which the mounting member is pulled out;

2. 2. The image forming apparatus according to claim 1, wherein the movable portion is made rotatable relative to the main body portion by being pushed up.

3. 3. The image forming apparatus according to claim 2, wherein the movable portion includes a roller that contacts and guides the paper removed from the fixing nip along the pull-out direction when the shutter is rotated to the closed position.

4. an elastic member that supports the roller on the movable part so that the roller can move up and down; a latch portion that connects the movable portion to the main body portion via the roller so as to rotate integrally with the main body portion, 4. The image forming apparatus according to claim 3, wherein when the roller is pushed up, the connection between the movable part and the main body part by the latch part is released, and the movable part becomes rotatable relative to the main body part.

5. 2. The image forming apparatus according to claim 1, further comprising a biasing member that biases the shutter to the closed position.

6. the mounting member is a drum unit including a photosensitive drum and a housing that accommodates the photosensitive drum, 2. The image forming apparatus according to claim 1, wherein the protrusion is provided on the housing.

Images