JP2017191247A - Image forming apparatus and fixing unit - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve positional accuracy of a detection target member with respect to a sensor in a longitudinal direction of a fixing unit, and to prevent a detection failure.SOLUTION: An image forming apparatus of the present invention comprises a fixing unit that fixes a toner image on a recording medium; and an apparatus body to which the fixing unit is attached. The fixing unit includes a detection target member 20 that operates in association with passage of the recording medium, a first positioning part 31 that is engaged with the detection target member 20 and regulates movement of the detection target member 20 in a longitudinal direction of the fixing unit, and a second positioning part 32 that is engaged with the apparatus body and regulates movement of the fixing unit with respect to the apparatus body. The apparatus body is provided with a sensor that detects operation of the detection target member 20, and the first positioning part 31 and second positioning part 32 are provided on the same component 25.SELECTED DRAWING: Figure 5

Description

  The present invention relates to an image forming apparatus and a fixing unit.

  2. Description of the Related Art Conventionally, an electrophotographic image forming apparatus includes a fixing device that fixes a toner image on a recording medium such as paper. For example, there is a fixing device that includes a detected member that operates as the recording medium passes and a sensor that detects the operation of the detected member (see Patent Document 1).

JP2013-29752A

  The fixing device described above may be integrated as a fixing unit and detachable from the main body of the image forming apparatus. In such a case, the sensor may be provided not in the fixing unit but in the main body of the image forming apparatus.

  However, if such a configuration is adopted, the positional accuracy of the detected member with respect to the sensor in the longitudinal direction of the fixing unit is lowered, and it becomes difficult to accurately detect the operation of the detected member by the sensor, causing the detection failure. There is a risk of becoming.

  In view of the above circumstances, an object of the present invention is to improve the positional accuracy of a member to be detected with respect to a sensor in the longitudinal direction of a fixing unit, and to prevent a detection failure.

  An image forming apparatus of the present invention includes a fixing unit that fixes a toner image on a recording medium, and an apparatus main body to which the fixing unit is mounted, and the fixing unit is detected as the recording medium passes. A member, a first positioning portion that engages with the detected member and restricts movement of the detected member in the longitudinal direction of the fixing unit; and engages with the apparatus main body, and the fixing unit with respect to the apparatus main body A second positioning part that regulates movement, and the apparatus main body is provided with a sensor that detects the operation of the detected member, and the first positioning part and the second positioning part are provided on the same part. It is provided.

  The first positioning part and the second positioning part may be provided on a fixing frame made of sheet metal.

  The fixing unit may further include a resin cover member that covers the fixing frame, and the detected member may be rotatably supported by the cover member.

  The detected member includes a rotating shaft extending along the longitudinal direction of the fixing unit, and a pair of ribs protruding from the outer peripheral surface of the rotating shaft at an interval in the longitudinal direction of the fixing unit, The first positioning portion may be sandwiched between the pair of ribs.

  The first positioning portion and the second positioning portion may be provided on a flat plate portion included in the fixing frame and may be located on the same plane.

  The image forming apparatus further includes another detected member that operates as the recording medium passes, and another sensor that detects the operation of the other detected member, wherein the sensor and the other sensor are , May be fixed to the same sensor substrate.

  The fixing unit includes a fixing member provided rotatably, a fixing nip formed in pressure contact with the fixing member, and a downstream side of the fixing nip in a recording medium conveyance direction. An actuator arranged, and when the recording medium that has passed through the fixing nip presses the actuator, the actuator presses the detected member, and the detected member may operate.

  A fixing unit of the present invention is a fixing unit that is mounted on an apparatus main body of an image forming apparatus and fixes a toner image onto a recording medium, and includes a detected member that operates as the recording medium passes, and the detected member. A first positioning portion that engages and restricts movement of the detected member in the longitudinal direction of the fixing unit; and a second positioning portion that engages with the apparatus main body and restricts movement of the fixing unit relative to the apparatus main body. The apparatus body is provided with a sensor for detecting the operation of the detected member, and the first positioning portion and the second positioning portion are provided in the same component. To do.

  According to the present invention, it is possible to improve the positional accuracy of the member to be detected with respect to the sensor in the longitudinal direction of the fixing unit and prevent a detection failure.

1 is a schematic diagram illustrating a multifunction machine according to an embodiment of the present invention. 1 is a perspective view showing a fixing unit according to an embodiment of the present invention. FIG. 2 is a cross-sectional view showing a fixing unit and its upper periphery according to an embodiment of the present invention. FIG. 3 is a perspective view showing a front end portion of a fixing unit according to an embodiment of the present invention. FIG. 3 is a perspective view showing a front fixing frame and its periphery in the fixing unit according to the embodiment of the present invention. FIG. 3 is a perspective view showing an actuator, a first detected member, and their surroundings in the fixing unit according to the embodiment of the present invention. FIG. 3 is a perspective view illustrating a state where the fixing unit is mounted on the unit mounting portion in the multifunction machine according to the embodiment of the present invention. FIG. 5 is a perspective view illustrating a state where the fixing unit is removed from the unit mounting portion in the multifunction machine according to the embodiment of the present invention. FIG. 3 is a cross-sectional view illustrating a state where the fixing unit is mounted on the unit mounting portion in the multifunction peripheral according to the embodiment of the present invention. FIG. 3 is a perspective view showing a paper discharge mechanism and a detection mechanism in the multifunction machine main body according to the embodiment of the present invention. FIG. 3 is a perspective view showing a housing of a paper discharge mechanism in the multifunction machine main body according to the embodiment of the present invention. FIG. 6 is a perspective view showing a state where the operation of the first detected member is released in the fixing unit according to the embodiment of the present invention. FIG. 6 is a perspective view showing a state in which the operation of the first detected member is released in the multifunction machine according to the embodiment of the present invention. FIG. 5 is a perspective view showing a state where a first detected member is operating in the fixing unit according to the embodiment of the present invention. FIG. 6 is a perspective view illustrating a state in which a first detected member is operating in the multifunction peripheral according to the embodiment of the present invention.

  Hereinafter, an MFP 1 (image forming apparatus) according to an embodiment of the present disclosure will be described with reference to the drawings. Arrows Fr, Rr, L, R, U, Lo attached to the respective drawings respectively indicate the front side, the rear side, the left side, the right side, the upper side, and the lower side of the multifunction machine 1.

  First, the configuration of the multifunction machine 1 will be described.

  As shown in FIG. 1, the multifunction machine 1 includes a box-shaped multifunction machine body 2 (apparatus body). An image reading device 3 for reading a document image is provided at the upper end portion of the multifunction machine main body 2. A paper discharge tray 4 is provided on the upper part of the multifunction machine main body 2. An intermediate transfer belt 5 and four image forming units 6 are accommodated in a substantially central portion of the multifunction machine main body 2. The four image forming units 6 correspond to black, cyan, magenta, and yellow toners, respectively. An exposure apparatus 7 is accommodated in the lower part of the multifunction machine main body 2. At the lower end portion of the multifunction machine main body 2, a paper feed cassette 8 that stores paper S (recording medium) is stored.

  A conveyance path P <b> 1 for the paper S is provided on the right side of the multifunction machine main body 2. A paper feed unit 9 is provided at the upstream end of the transport path P1. A secondary transfer unit 10 is provided in the middle portion of the transport path P1. A fixing unit 11 is provided downstream of the transport path P1. A reverse path P2 for double-sided printing is provided on the right side of the transport path P1.

  Next, the operation of the multifunction device 1 will be described.

  First, an electrostatic latent image is formed in each image forming unit 6 by light from the exposure device 7 (see a two-dot chain line arrow in FIG. 1). This electrostatic latent image is developed into a toner image in each image forming unit 6. This toner image is primarily transferred from each image forming unit 6 to the intermediate transfer belt 5. As a result, a full-color toner image is formed on the intermediate transfer belt 5.

  Further, the paper S taken out from the paper feed cassette 8 by the paper feed unit 9 is transported downstream in the transport path P <b> 1 and enters the secondary transfer unit 10. In the secondary transfer unit 10, the full-color toner image formed on the intermediate transfer belt 5 is secondarily transferred to the paper S. The sheet S on which the toner image is secondarily transferred is further conveyed downstream in the conveyance path P1 and enters the fixing unit 11. In the fixing unit 11, the toner image is fixed on the paper S. The paper S on which the toner image is fixed is discharged onto the paper discharge tray 4 or conveyed to the reverse path P2 for duplex printing.

  Next, the fixing unit 11 will be further described with reference to FIGS.

  Referring to FIG. 2, the entire fixing unit 11 is integrated. The fixing unit 11 has a long shape in the front-rear direction. That is, in the present embodiment, the front-rear direction is the longitudinal direction of the fixing unit 11. 2 and the subsequent drawings indicate the inside in the front-rear direction, and the arrow O appropriately applied in the drawings after FIG. 2 indicates the front-rear direction outside. Further, an arrow Y appropriately attached to each of the drawings after FIG. 3 indicates a paper transport direction (hereinafter referred to as “paper transport direction Y”).

  3 and 4, the fixing unit 11 includes a box-shaped unit main body 14, a heat roller 15 (fixing member) accommodated in the left side portion of the unit main body 14, and a right side portion of the unit main body 14. The accommodated press roller 16 (pressure member), an entry guide 17 provided below the press roller 16, a discharge guide 18 provided above the unit body 14, and an actuator 19 attached to the upper part of the unit body 14. And the 1st to-be-detected member 20 (to-be-detected member) attached to the front-end part of the unit main body 14 is provided.

  Referring to FIG. 4, a fixing frame 25 </ b> Fr is provided at the front end portion of the unit main body 14. The fixing frame 25Fr is composed of a single sheet metal. Referring to FIG. 5, the fixing frame 25 </ b> Fr includes a base plate 26 and a bent plate 27 that is bent toward the front side from the right end portion of the base plate 26. The base plate 26 is provided with a flat plate portion 28 (hereinafter referred to as “flat plate portion 28”). The flat plate portion 28 is provided perpendicular to the front-rear direction. A bearing hole 29 is provided on the left side of the flat plate portion 28. A first positioning portion 31 is provided above the bearing hole 29 above the flat plate portion 28. A second positioning portion 32 is provided on the left end portion of the flat plate portion 28 on the left side of the bearing hole 29. Thus, since both the 1st positioning part 31 and the 2nd positioning part 32 are provided in the flat plate part 28, they are located on the same plane. The second positioning portion 32 protrudes toward the left side.

  Referring to FIG. 3, a fixing frame 25 </ b> Rr is provided at the rear end portion of the unit main body 14. Since the configuration of the fixing frame 25Rr is the same as the configuration of the fixing frame 25Fr, description thereof is omitted.

  With reference to FIG. 4, a cover member 33 is provided at the front end of the unit main body 14. The cover member 33 is made of resin. The cover member 33 is provided so as to cover the front side (front-rear direction outer side) of the fixing frame 25Fr. A pair of attachment pieces 34 are provided on the upper end portion of the cover member 33.

  Referring to FIG. 3, the heat roller 15 has a long cylindrical shape in the front-rear direction. The heat roller 15 accommodates a heater 35 composed of a halogen lamp or the like. A separation member 36 is provided above the heat roller 15. The heat roller 15 is connected to a drive source 37 configured by a motor or the like via a drive gear train (not shown).

  Referring to FIG. 5, both front and rear end portions (only the front end portion is shown in FIG. 5) of heat roller 15 are provided on fixing frames 25Fr and 25Rr (only fixing frame 25Fr is shown in FIG. 5) of unit body 14. The bearing hole 29 is mounted via a bearing 38. Thereby, the heat roller 15 is rotatably supported by the unit main body 14.

  With reference to FIG. 3, the press roller 16 has comprised the column shape long in the front-back direction. The press roller 16 faces the heat roller 15. The press roller 16 is pressed toward the left side (heat roller 15 side) by a pressing spring (not shown) and is in pressure contact with the heat roller 15. Thereby, a fixing nip N is formed between the heat roller 15 and the press roller 16. The press roller 16 is rotatably supported by the unit body 14.

  The approach guide 17 is disposed below the fixing nip N (upstream side in the paper transport direction Y). The left surface of the entry guide 17 (the surface facing the transport path P1) is inclined leftward toward the upper side.

  The discharge guide 18 faces the transport path P1 and the reverse path P2. A plurality of discharge rollers 40 (discharge members) are provided below the discharge guide 18. The plurality of discharge rollers 40 are disposed on the upper side of the fixing nip N (on the downstream side in the paper transport direction Y).

  The actuator 19 is disposed above the fixing nip N (downstream side in the paper transport direction Y) and below the discharge roller 40 (upstream side in the paper transport direction Y).

  Referring to FIG. 6, the actuator 19 includes a straight rod-shaped shaft portion 41 extending along the front-rear direction, a pressed portion 42 extending radially outward from the rear end portion of the shaft portion 41, and the shaft portion 41. And a pressing portion 43 extending radially outward from the front end portion. The actuator 19 is supported by the unit main body 14 so as to be rotatable around the shaft portion 41. The pressed portion 42 is disposed at the center in the front-rear direction of the fixing unit 11.

  The first detected member 20 includes a straight rod-shaped first rotating shaft 44 extending along the front-rear direction, a pair of ribs 45 projecting from the outer peripheral surface of the first rotating shaft 44, and a rear portion of the first rotating shaft 44. A first pressed piece 46 that extends radially outward from the first rotating piece 44, and a first detected piece 47 that extends radially outward from the front end of the first rotating shaft 44.

  The first rotation shaft 44 of the first detected member 20 is disposed in parallel with the shaft portion 41 of the actuator 19 and on a non-identical axis. With reference to FIG. 4, both front and rear end portions of the first rotation shaft 44 are rotatably attached to the attachment pieces 34 of the cover member 33 of the unit main body 14. Thus, the first detected member 20 is rotatably supported by the cover member 33 of the unit main body 14.

  The pair of ribs 45 of the first detected member 20 are provided at intervals in the front-rear direction. The pair of ribs 45 are disposed on the front side (front-rear direction outer side) of the first pressed piece 46 and on the rear side (front-rear direction inner side) of the first detected piece 47. Between the pair of ribs 45, the first positioning portion 31 of the fixing frame 25Fr of the unit body 14 is sandwiched. That is, the first positioning portion 31 is engaged with the pair of ribs 45. Accordingly, the movement of the first detected member 20 in the front-rear direction with respect to the fixing frame 25Fr of the unit main body 14 is restricted.

  Next, the MFP main body 2 will be further described with reference to FIGS. 3 and 7 to 11.

  Referring to FIG. 7, a unit mounting portion 51 is provided at the right end portion of the multifunction device main body 2. The unit mounting part 51 is opened toward the right side and is covered with an openable / closable cover (not shown). The fixing unit 11 is detachably mounted on the unit mounting portion 51. 7 to 9 indicate the mounting direction of the fixing unit 11 to the unit mounting portion 51 (hereinafter referred to as “mounting direction Z”).

  Referring to FIG. 8, a stay 52 is provided on the left side of the unit mounting portion 51 (the back side portion in the mounting direction Z) of the multifunction device main body 2. Engagement holes 53 are provided in the front lower portion and the rear lower portion of the stay 52, respectively. Referring to FIG. 9, in each engagement hole 53 (in FIG. 9, only the front engagement hole 53 is shown), each fixing frame 25Fr, 25Rr (in FIG. 9, the fixing frame) of the unit body 14 of the fixing unit 11 is shown. The second positioning portion 32 provided on the frame 25Fr only) is inserted. That is, the second positioning portions 32 of the fixing frames 25Fr and 25Rr are engaged with the engagement holes 53. Thereby, the movement of the fixing unit 11 in the vertical direction and the front-rear direction with respect to the multifunction peripheral body 2 is restricted.

  Referring to FIG. 7, the multifunction device main body 2 is provided with a paper discharge mechanism 55 above the unit mounting portion 51. The paper discharge mechanism 55 is attached to the lower surface of the sheet metal member 54 provided in the multifunction machine main body 2. Referring to FIG. 3, the paper discharge mechanism 55 faces the fixing unit 11 via the reverse path P2.

  Referring to FIG. 10, the paper discharge mechanism 55 includes a housing 56, a pair of conveyance rollers 57 (conveyance member) attached to the left side portion of the housing 56, and a second detected member 58 attached to the left end portion of the housing 56. (Other detected members).

  Referring to FIG. 11, the housing 56 of the paper discharge mechanism 55 is made of resin. The housing 56 includes a main body portion 59 extending along the front-rear direction and an attachment portion 60 extending downward from the front end portion of the main body portion 59. An attachment frame 61 is provided at the left end of the main body 59. A pair of holding frames 62 are provided on the left side of the main body 59. A snap fit 65 is provided on each of the upper right portion and the lower right portion of the attachment portion 60. Boss 66 is provided in the right side part and the center part of attachment part 60, respectively.

  Referring to FIG. 10, the pair of transport rollers 57 of the paper discharge mechanism 55 are held in a rotatable state by a pair of holding frames 62 provided on the main body portion 59 of the housing 56. Referring to FIG. 3, each transport roller 57 is disposed on the upper left side of the fixing unit 11 (downstream side in the paper transport direction Y). Each transport roller 57 is in pressure contact with a counter roller 70 provided therebelow.

  Referring to FIG. 10, the second detected member 58 of the paper discharge mechanism 55 includes a straight rod-shaped second rotating shaft 67 extending along the front-rear direction, and a radially outer side from the front-rear center of the second rotating shaft 67. And a second detected piece 69 extending radially outward from the front end portion of the second rotation shaft 67. The second rotation shaft 67 is rotatably attached to the attachment frame 61 of the main body 59 of the housing 56. As a result, the second detected member 58 is rotatably supported by the housing 56.

  Referring to FIG. 10, the multifunction device main body 2 is provided with a detection mechanism 71 in front of the paper discharge mechanism 55. The detection mechanism 71 includes a sensor substrate 72, a first sensor 73 (sensor) fixed to the right side of the sensor substrate 72, a second sensor 74 (other sensors) fixed to the left side of the sensor substrate 72, It has.

  A fitting hole 75 is provided in each of the right side and the center of the sensor substrate 72. Then, each boss 66 of the mounting portion 60 of the housing 56 is fitted to each fitting hole 75 and the upper and lower end portions of the sensor substrate 72 are engaged with each snap fit 65 of the mounting portion 60, thereby A sensor substrate 72 is attached.

  The first sensor 73 is configured by a PI sensor (Photo Interrupter Sensor). The first sensor 73 includes a first light emitting unit 76 and a first light receiving unit 77 that receives light emitted from the first light emitting unit 76.

  The second sensor 74 is configured by a PI sensor (Photo Interrupter Sensor). The second sensor 74 includes a second light emitting unit 78 and a second light receiving unit 79 that receives light emitted from the second light emitting unit 78.

  An operation of fixing the toner image on the paper S by the fixing unit 11 in the multi-function machine 1 configured as described above will be described.

  When the toner image is fixed on the paper S by the fixing unit 11, the heat roller 15 is rotated by the drive source 37 (see FIG. 3) (see arrow A in FIG. 3). When the heat roller 15 rotates in this manner, the press roller 16 that is in pressure contact with the heat roller 15 is driven to rotate in the opposite direction to the heat roller 15 (see arrow B in FIG. 3). Further, when the toner image is fixed on the paper S by the fixing unit 11, the heater 35 is operated and the heat roller 15 is heated by the heater 35.

  When the sheet S is introduced into the fixing unit 11 in this state, the sheet S enters the fixing nip N while being guided by the left surface of the entry guide 17. As a result, the toner image on the paper S is heated and melted and fixed on the paper S. The sheet S that has passed through the fixing nip N is discharged to the outside of the fixing unit 11 by the plurality of discharge rollers 40, and then discharged to the discharge tray 4 by the pair of transport rollers 57.

  Next, an operation of detecting that the sheet S has passed through the fixing unit 11 in the multi-function device 1 configured as described above will be described.

  When the sheet S does not pass through the fixing unit 11, the pressed portion 42 of the actuator 19 crosses the transport path P1 as indicated by a solid line in FIG. As shown in FIGS. 12 and 13, the first detected piece 47 of the first detected member 20 has a substantially horizontal posture, and the first light emitting unit 76 of the first sensor 73 performs the first operation. The optical path to the light receiving unit 77 is not blocked.

  On the other hand, when the sheet S passes through the fixing unit 11, the leading end of the sheet S that has passed through the fixing nip N presses the pressed portion 42 of the actuator 19 upward. By this pressing, the actuator 19 rotates around the shaft portion 41 as indicated by a two-dot chain line in FIG. Accordingly, as shown in FIG. 14, the pressing portion 43 of the actuator 19 presses the first pressed piece 46 of the first detected member 20 upward, and the first detected member 20 is the first detected member 20. It rotates around the rotation shaft 44. That is, the first detected member 20 operates. Accordingly, as shown in FIG. 15, the first detected piece 47 of the first detected member 20 blocks the optical path from the first light emitting unit 76 of the first sensor 73 to the first light receiving unit 77. The first sensor 73 detects the operation of the first detected member 20. Thereby, it is detected that the sheet S passes through the fixing unit 11.

  Next, an operation of detecting that the sheet S has passed through the paper discharge mechanism 55 in the multi-function device 1 configured as described above will be described.

  When the paper S has not passed through the paper discharge mechanism 55, as shown by a solid line in FIG. 3, the second pressed piece 68 of the second detected member 58 crosses the transport path P1. Further, as shown in FIG. 13, the second detected piece 69 of the second detected member 58 blocks the optical path from the second light emitting unit 78 of the second sensor 74 to the second light receiving unit 79.

  On the other hand, when the paper S passes through the paper discharge mechanism 55, the leading end of the paper S presses the second pressed piece 68 of the second detected member 58 toward the left. By this pressing, the second detected member 58 rotates about the second rotation shaft 67 as indicated by a two-dot chain line in FIG. That is, the second detected member 58 operates. Accordingly, the second detected piece 69 of the second detected member 58 does not block the optical path from the second light emitting unit 78 of the second sensor 74 to the second light receiving unit 79, so that the second sensor 74 is 2 The operation of the detected member 58 is detected. Thereby, it is detected that the paper S passes through the paper discharge mechanism 55.

  In the present embodiment, as described above, the multifunction device main body 2 is provided with the first sensor 73 that detects the operation of the first detected member 20 of the fixing unit 11. By adopting such a configuration, the number of electrical components such as harnesses and connectors can be reduced compared to the case where the sensor that detects the operation of the first detected member 20 of the fixing unit 11 is provided in the fixing unit 11. It is possible to reduce the number of parts of the multifunction machine 1. Accordingly, the manufacturing cost of the multifunction machine 1 can be reduced. In addition, since the first sensor 73 is not easily affected by the heat generated by the fixing unit 11, the malfunction of the first sensor 73 can be suppressed.

  On the other hand, when the first sensor 73 is provided in the multifunction device main body 2 as described above, it is difficult to obtain the positional accuracy of the first detected member 20 in the front-rear direction with respect to the first sensor 73. In particular, when the heater 35 is in operation, the entire fixing unit 11 generates heat, and each component of the fixing unit 11 is deformed by thermal expansion. Therefore, the positional accuracy of the first detected member 20 in the front-rear direction with respect to the first sensor 73 is further improved. It becomes more difficult to put out.

  Therefore, in the present embodiment, the first positioning portion 31 that restricts the movement of the first detected member 20 in the front-rear direction and the second positioning portion 32 that restricts the movement of the fixing unit 11 relative to the multifunction device main body 2 are the same. Are provided on the fixing frame 25Fr. By adopting such a configuration, the positional accuracy of the first detected member 20 in the front-rear direction with respect to the first sensor 73 can be improved. Accordingly, the operation of the first detected member 20 can be accurately detected by the first sensor 73, and a detection failure can be prevented.

  Further, the fixing frame 25Fr provided with the first positioning portion 31 and the second positioning portion 32 is made of sheet metal. By adopting such a configuration, the first positioning unit 31 and the second positioning unit 32 are heated when the fixing unit 11 generates heat as compared with the case where the first positioning unit 31 and the second positioning unit 32 are provided in the resin component. The positional relationship of becomes difficult to change. Accordingly, the positional accuracy of the first detected member 20 in the front-rear direction with respect to the first sensor 73 can be improved.

  The first detected member 20 is rotatably supported by a resin cover member 33. By adopting such a configuration, the first detected member 20 can be smoothly rotated.

  Further, the first positioning portion 31 is sandwiched between the pair of ribs 45. By adopting such a configuration, the movement of the first detected member 20 in the front-rear direction can be restricted without complicating the configuration of the fixing frame 25Fr.

  The first positioning portion 31 and the second positioning portion 32 are provided on the flat plate portion 28 of the fixing frame 25Fr, and are located on the same plane. By adopting such a configuration, it is possible to further improve the positional accuracy of the first detected member 20 with respect to the first sensor 73 in the front-rear direction.

  The first sensor 73 and the second sensor 74 are fixed to the same sensor substrate 72. By adopting such a configuration, the number of electrical components such as harnesses and connectors can be further reduced, and the number of parts of the multifunction device 1 can be further reduced. Accordingly, the manufacturing cost of the multifunction machine 1 can be further reduced.

  The actuator 19 is disposed above the fixing nip N (on the downstream side in the paper transport direction Y). Therefore, it is possible to confirm that the sheet S has passed through the fixing nip N at an appropriate timing and that no JAM (paper jam) has occurred.

  Further, when the sheet S that has passed through the fixing nip N presses the actuator 19, the actuator 19 presses the first detected member 20, and the first detected member 20 is activated. By adopting such a configuration, it is possible to increase the degree of freedom of the layout of the first detected member 20 as compared with the case where the first detected member 20 is directly pressed by the paper S.

  In the present embodiment, a case has been described in which when the paper S presses the actuator 19, the actuator 19 presses the first detected member 20 and the first detected member 20 operates. On the other hand, in other different embodiments, the first detected member 20 may be operated by the sheet S directly pressing the first detected member 20.

  In the present embodiment, the case where the heat roller 15 is used as a fixing member has been described. On the other hand, in other different embodiments, a fixing belt may be used as a fixing member.

  In this embodiment, the case where the configuration of the present invention is applied to the multifunction device 1 has been described. However, in another different embodiment, the configuration of the present invention is applied to an image forming apparatus other than the multifunction device 1 such as a printer, a copier, and a facsimile. It is also possible to apply.

1 MFP (image forming device)
2 MFP body (device body)
11 Fixing unit 15 Heat roller (fixing member)
16 Press roller (pressure member)
19 Actuator 20 First detected member (detected member)
25Fr Fixing frame 28 Flat part (flat part)
31 1st positioning part 32 2nd positioning part 33 Cover member 44 1st rotating shaft 45 A pair of rib 58 2nd to-be-detected member (other to-be-detected member)
72 sensor board 73 first sensor (sensor)
74 Second sensor (other sensors)
N fixing nip S paper (recording medium)
Y Paper transport direction

Claims (8)

A fixing unit for fixing a toner image on a recording medium;
An apparatus main body to which the fixing unit is mounted,
The fixing unit includes:
A detected member that operates as the recording medium passes;
A first positioning portion that engages with the detected member and restricts movement of the detected member in the longitudinal direction of the fixing unit;
A second positioning portion that engages with the apparatus main body and restricts movement of the fixing unit with respect to the apparatus main body,
The device body is provided with a sensor for detecting the operation of the detected member,
The image forming apparatus, wherein the first positioning unit and the second positioning unit are provided in the same component.   The image forming apparatus according to claim 1, wherein the first positioning unit and the second positioning unit are provided on a fixing frame formed of a sheet metal. The fixing unit further includes a resin cover member that covers the fixing frame,
The image forming apparatus according to claim 2, wherein the detected member is rotatably supported by the cover member. The detected member is
A rotating shaft extending along the longitudinal direction of the fixing unit;
A pair of ribs projecting from the outer peripheral surface of the rotating shaft at an interval in the longitudinal direction of the fixing unit;
The image forming apparatus according to claim 2, wherein the first positioning unit is sandwiched between the pair of ribs.   The said 1st positioning part and the said 2nd positioning part are provided in the flat plate-shaped part contained in the said fixing frame, and are located on the same plane, Any one of Claims 2-4 The image forming apparatus according to claim 1. Other detected members that operate as the recording medium passes,
Another sensor for detecting the operation of the other detected member, and
The image forming apparatus according to claim 1, wherein the sensor and the other sensor are fixed to the same sensor substrate. The fixing unit includes:
A fixing member provided rotatably;
A pressure member provided in a rotatable manner to form a fixing nip by pressing against the fixing member;
An actuator disposed on the downstream side of the fixing nip in the conveyance direction of the recording medium,
The recording medium according to claim 1, wherein when the recording medium that has passed through the fixing nip presses the actuator, the actuator presses the detected member, and the detected member operates. Image forming apparatus. A fixing unit that is mounted on a main body of an image forming apparatus and fixes a toner image on a recording medium;
A detected member that operates as the recording medium passes;
A first positioning portion that engages with the detected member and restricts movement of the detected member in the longitudinal direction of the fixing unit;
A second positioning portion that engages with the apparatus main body and restricts movement of the fixing unit with respect to the apparatus main body,
The device body is provided with a sensor for detecting the operation of the detected member,
The fixing unit, wherein the first positioning portion and the second positioning portion are provided in the same part.

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