Image forming device

Abstract

To provide an image formation apparatus in which an actuator and a sensor can be arranged while maintaining the size of a device body even when the size of a fixation device is increased.SOLUTION: An image formation apparatus 1 comprises: a fixing unit 6 which has a heater 611 and a fixation frame 63 that supports the heater 611; a chute 22 which can be rotated between a path formation position and a path opening position; an optical sensor 81; and an actuator 83 which has a shaft 830, a first lever 831 and a second lever 832, and is movable to a first position where the first lever 831 is in contact with a rotation stop rib 223 in such a state that the chute 22 is located at the path formation position, a second position where the first lever 831 is apart from the rotation stop rib 223 in such a state that the chute 22 is located at the path formation position and a third position where the first lever 831 is apart from the rotation stop rib 223 in such a state that the chute 22 is located at the path opening position. The actuator 83 and the optical sensor 81 are attached to the fixation frame 63.SELECTED DRAWING: Figure 8

Description

[Technical Field]

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

[0002] Conventionally, there is known an image forming device that includes a chute that forms a conveying path downstream in the sheet conveying direction of the fixing device and is rotatable relative to the device body, an actuator that is swingably mounted on the chute and has a lever that protrudes toward the conveying path, and a sensor that is mounted on the device body and detects the actuator, and is configured so that the sensor detects the sheet when the actuator swings (see, for example, Patent Document 1).

[0003] In such an image forming apparatus, the actuator is provided in the chute and the sensor is provided in the main body of the apparatus, so the sensor must be located below the chute or at the end of the chute in the width direction perpendicular to the sheet conveying direction. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2013-250391 Summary of the Invention [Problem to be solved by the invention]

[0005] On the other hand, for example, if the fixing device installed in an image forming device becomes larger, if an attempt is made to place a sensor while maintaining the size of the device body, the sensor will interfere with parts such as gears located at the widthwise end of the chute, making it difficult to secure space to place the sensor.

[0006] Therefore, the present invention provides an image forming apparatus in which the actuator and the sensor can be arranged while maintaining the size of the apparatus main body even when the fixing device is enlarged. [Means for solving the problem]

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

[0008] That is, the image forming apparatus includes a fixing device that fixes toner onto a sheet, the fixing device including a heater and a fixing frame that supports the heater; a chute that is rotatable between a path forming position that forms a transport path downstream in a sheet transport direction of the fixing device and a path opening position that opens the transport path; an optical sensor that has a light-emitting element that emits light and a light-receiving element that can receive light emitted from the light-emitting element; an actuator that is contactable with a rotation-stopping rib, the actuator including a shaft that extends in a width direction perpendicular to the sheet transport direction; and a first lever that protrudes from the shaft and is contactable with the rotation-stopping rib. and a second lever protruding from the shaft and capable of blocking light emitted from the light-emitting element of the optical sensor, the actuator being movable to a first position where the first lever contacts the anti-rotation rib when the chute is positioned at the path forming position, a second position where the first lever and the anti-rotation rib are spaced apart when the chute is positioned at the path forming position, and a third position where the first lever and the anti-rotation rib are spaced apart when the chute is positioned at the path opening position, wherein the actuator and the optical sensor are supported by the fixing frame.

[0009] This allows the actuator and optical sensor to be located in the center of the device body in the width direction, preventing interference with parts such as gears located at the width ends of the device body. Furthermore, since the tolerance for the mounting positions of the actuator and optical sensor can be reduced, an optical sensor with a small gap between the light-emitting element and the light-receiving element can be used. Therefore, even if the fixing unit is enlarged, the actuator and optical sensor can be located while maintaining the size of the device body.

[0010] The rotation stop rib is provided on the chute.

[0011] This allows the actuator to be made smaller, and even if the fixing unit is enlarged, the actuator and the optical sensor can be arranged while maintaining the size of the main body of the apparatus.

[0012] The actuator also has a third lever that protrudes from the shaft and is positioned on the conveying path, and when the chute is positioned at the path forming position, a sheet being conveyed along the conveying path abuts the third lever, causing the sheet to rotate from the first position in a first direction and move to the second position, and when the chute is positioned at the path opening position and the second lever and the rotation stop rib are separated, the sheet to rotate from the first position in a second direction opposite to the first direction and move to the third position.

[0013] This allows the rotation stop rib provided on the chute to have a simple structure.

[0014] The device also includes a main body frame that covers the fixing unit, and the main body frame includes a restricting wall that abuts against the third lever when the actuator moves from the first position to the third position, thereby restricting rotation of the actuator in the second direction.

[0015] This prevents the third lever from moving beyond the third position in the second direction, causing the anti-rotation rib and the first lever to lose contact when the chute, which is in the path-opening position, rotates to the path-forming position.

[0016] The fixing frame also has a recess that does not interfere with the second lever when the actuator is in the second position.

[0017] This allows the actuator and the fixing frame to be disposed close to each other, thereby saving space.

[0018] The actuator and the optical sensor are also supported by a support frame that supports the actuator and the optical sensor. The support frame is attached to the fixing frame, so that the actuator and the optical sensor are supported by the fixing frame.

[0019] In this way, by supporting the actuator and optical sensor as a unit by the support frame and then attaching it to the fixing frame, the actuator and optical sensor can be made smaller and placed in the center of the width direction of the device body. Furthermore, when replacing the fixing unit, the actuator and optical sensor supported by the support frame can be easily removed from the fixing frame, allowing the actuator and optical sensor to be reused.

[0020] The support frame also has an upstream frame disposed on the upstream side in the sheet transport direction, and the upstream frame is positioned between the fixing frame, the actuator, and the optical sensor.

[0021] This allows the upstream frame to shield the heat from the fixing unit, thereby reducing the influence of heat on the actuator and the optical sensor.

[0022] The support frame also has a downstream frame located on the opposite side of the actuator from the upstream frame side, and an opening is formed between the upstream frame and the downstream frame that opens on the side where the second lever extends further than the actuator and communicates with the outside, and the chute has a cover that covers the opening in the support frame when positioned in the path forming position.

[0023] This allows the cover to prevent external light from entering the support frame through the opening, reducing malfunction of the light sensor.

[0024] The support frame also includes a transport rib for guiding the sheet being transported.

[0025] This allows the support frame to also serve as a rib for guiding the seat, thereby reducing the number of parts.

[0026] The chute also has a plurality of guide ribs spaced apart in the width direction, the plurality of guide ribs including a first guide rib arranged adjacent to the conveying rib in the width direction and a second guide rib arranged farther away from the conveying rib in the width direction than the first guide rib, and the length of the first guide rib in the sheet conveying direction is shorter than the length of the second guide rib.

[0027] In this way, because the first guide rib is disposed adjacent to the conveying rib, even if the length in the sheet conveying direction is made short, the conveyed sheet can be guided by the first guide rib and the conveying rib, which allows the chute to be made compact.

[0028] The chute also has a pressing member that presses the actuator in a direction in which the actuator moves from the first position to the third position when the chute rotates from the path forming position to the path opening position.

[0029] This allows the actuator to be forcibly moved from the first position to the third position in conjunction with the operation of rotating the chute from the path forming position to the path opening position.

[0030] The pressing member is an arm that extends from the chute toward the actuator and engages with the actuator when the chute rotates from the path forming position to the path opening position.

[0031] This allows the actuator to be moved from the first position to the third position in conjunction with the rotation of the chute from the path forming position to the path opening position, with a simple configuration. [Effects of the Invention]

[0032] According to the present invention, even if the fixing unit is enlarged, the actuator and the optical sensor can be arranged while maintaining the size of the main body of the apparatus. [Brief explanation of the drawings]

[0033] [Figure 1] FIG. 2 is a central cross-sectional view showing the image forming apparatus. [Figure 2] FIG. [Figure 3] FIG. 2 is a perspective view showing a heating unit and a pressure roller of the fixing unit. [Figure 4] FIG. [Figure 5] FIG. 2 is a side view showing the fixing unit, the chute, and the paper discharge sensor unit. [Figure 6] FIG. 2 is a bottom view showing the fixing unit, the chute, and the paper discharge sensor unit. [Figure 7] 1A is a perspective view showing the chute, FIG. 1B is a front view showing the chute, and FIG. 1C is a side view showing the chute. [Figure 8] 10 is a side cross-sectional view showing the paper discharge sensor unit in a state where the actuator has moved to a first position. FIG. [Figure 9] 1A is a front view showing the paper discharge sensor unit, FIG. 1B is a rear view showing the paper discharge sensor unit, and FIG. 1C is a perspective view showing the chute. [Figure 10] 1A is a perspective view showing the actuator, FIG. 1B is a front view showing the actuator, and FIG. 1C is a side view showing the actuator. [Figure 11] FIG. 2 is a plan view showing the fixing unit, the chute, and the paper discharge sensor unit. [Figure 12] 10 is a side cross-sectional view showing the paper discharge sensor unit in a state where the actuator has moved to a second position. FIG. [Figure 13] FIG. 10 is a side cross-sectional view showing the paper discharge sensor unit when the actuator is moved to a third position. [Figure 14] FIG. 10 is a side view showing a second embodiment of the chute and the paper discharge sensor unit. DETAILED DESCRIPTION OF THE INVENTION

[0034] Next, an embodiment of the present invention will be described with reference to the accompanying drawings.

[0035] [Image forming device] An image forming apparatus 1 shown in FIG. 1 is one embodiment of the image forming apparatus according to the present invention, and is a laser printer that forms an image on a sheet S by electrophotography.

[0036] In the following description, the right side in Fig. 1 is defined as the front side of the image forming apparatus 1, the left side in Fig. 1 is defined as the rear side of the image forming apparatus 1, the front side of the paper in Fig. 1 is defined as the left side of the image forming apparatus 1, and the back side of the paper in Fig. 1 is defined as the right side of the image forming apparatus 1. In addition, the upper and lower sides in Fig. 1 are defined as the upper and lower sides of the image forming apparatus 1, respectively.

[0037] The image forming device 1 is one embodiment of the image forming device according to the present invention, and comprises a device main body 2, a paper feed section 3, an image forming section 5, a fixing unit 6, a paper discharge section 7, and a paper discharge sensor unit 8.

[0038] The device main body 2 houses a paper feed section 3, an image forming section 5, a fixing unit 6, a paper discharge section 7, and a paper discharge sensor unit 8. An opening 2A is formed on the rear surface of the device main body 2, and the device main body 2 has a rear cover 21 that can open and close the opening 2A. The rear cover 21 is configured to be rotatable about a rotation shaft 21a at the bottom end, and by rotating about the rotation shaft 21a, it can move between a closed position that closes the opening 2A and an open position that opens the opening 2A.

[0039] The paper feed unit 3 includes a paper feed tray 30 that supports the sheet S, a paper feed mechanism 32, a conveying roller pair 33, and a registration roller pair 34. The paper feed unit 3 is disposed at the bottom of the apparatus main body 2, and conveys the sheet S supported on the paper feed tray 30 to the image forming unit 5. The image forming apparatus 1 has a conveying path P1 for the sheet S that runs from the paper feed unit 3 to the paper discharge unit 7 via the image forming unit 5.

[0040] The sheet feed tray 30 has a pressure plate 31 and a pressing plate 311. The pressure plate 31 is a plate-shaped member that supports the sheets S from below. The pressure plate 31 is rotatable around a rotation fulcrum 31a at its rear end, and by rotating around the rotation fulcrum 31a, it can be raised and lowered between a lowered position and an upper position. The pressing plate 311 is located below the pressure plate 31, and can raise and lower the pressure plate 31 between the lowered position and the upper position.

[0041] The paper feed mechanism 32 includes a paper feed roller 32a, a separation roller 32b, and a separation pad 32c. The paper feed roller 32a is a roller for sending the sheet S supported in the paper feed tray 30 toward the separation roller 32b. The separation roller 32b is disposed downstream of the paper feed roller 32a in the sheet conveying direction, and the separation pad 32c is disposed opposite the separation roller 32b and is biased toward the separation roller 32b.

[0042] The sheets S sent by the paper feed roller 32a toward the separation roller 32b are separated one by one between the separation roller 32b and the separation pad 32c. The separated sheets S are sent to the conveying path P1.

[0043] The sheet S sent to the conveying path P is conveyed toward the image forming unit 5 by a pair of conveying rollers 33 and a pair of registration rollers 34. The pair of registration rollers 34 regulates the movement of the leading edge of the conveyed sheet S, temporarily stops the sheet S, and then conveys the sheet S toward the image forming unit 5 at a predetermined timing.

[0044] The image forming unit 5 is disposed downstream of the paper feed unit 3 in the sheet transport direction, and forms an image on the sheet S transported from the paper feed unit 3. The image forming unit 5 includes a process cartridge 50 that transfers an image onto the surface of the sheet S transported from the paper feed unit 3, and an exposure unit 56 that exposes the surface of a photosensitive drum 54 in the process cartridge 50.

[0045] The process cartridge 50 is located above the paper feed section 3 within the device main body 2, and is equipped with a developer storage chamber 51, a supply roller 52, a developing roller 53, a photosensitive drum 54, a transfer roller 55, etc.

[0046] The exposure unit 56 is equipped with a laser diode, a polygon mirror, a lens, a reflecting mirror, etc., and exposes the surface of the photosensitive drum 54 by irradiating the photosensitive drum 54 with laser light based on image data input to the image forming apparatus 1.

[0047] Toner that will become the developer is stored in the developer storage chamber 51. The toner stored in the developer storage chamber 51 is stirred by a stirring member (not shown) and sent to the supply roller 52. The supply roller 52 further supplies the toner sent from the developer storage chamber 51 to the developing roller 53.

[0048] The developing roller 53 is disposed in close contact with the supply roller 52, and carries toner supplied from the supply roller 52 and positively charged by a sliding contact member (not shown). A developing bias is applied to the developing roller 53 by a bias application means (not shown).

[0049] The photosensitive drum 54 is disposed adjacent to the developing roller 53. The surface of the photosensitive drum 54 is uniformly charged by a charger (not shown) and then exposed by the exposure unit 56. The exposed portion of the photosensitive drum 54 has a lower potential than the other portions, and an electrostatic latent image based on the image data is formed on the photosensitive drum 54. Then, positively charged toner is supplied from the developing roller 53 to the surface of the photosensitive drum 54 on which the electrostatic latent image has been formed, thereby visualizing the electrostatic latent image into a toner image.

[0050] The transfer roller 55 is disposed opposite the photosensitive drum 54, and a transfer bias is applied to it by a bias application means (not shown). With the transfer bias applied to the surface of the transfer roller 55, the toner image formed on the surface of the photosensitive drum 54 is transferred to the surface of the sheet S by conveying the sheet S while sandwiching it between the photosensitive drum 54 on which the toner image has been formed and the transfer roller 55. In other words, the photosensitive drum 54 transfers the toner image onto the sheet S.

[0051] The fixing device 6 includes a heating unit 61 and a pressure roller 62, and fixes the toner image transferred onto the sheet S in the image forming section 5. The heating unit 61 is heated by supplying power from a power source (not shown). The pressure roller 62 is disposed opposite the heating unit 61. One of the heating unit 61 and the pressure roller 62 is biased toward the other by a biasing mechanism (not shown), and the heating unit 61 and the pressure roller 62 are in close contact with each other.

[0052] When the sheet S onto which the toner image has been transferred is conveyed to the fixing device 6, the sheet S is conveyed while being sandwiched between the heating unit 61 and the pressure roller 62, whereby the sheet S is heated and the toner image is fixed onto the sheet S. In other words, the heating unit 61 and the pressure roller 62 fix the toner onto the sheet S.

[0053] The paper discharge unit 7 is located downstream of the fixing unit 6 in the sheet conveying direction, and discharges the sheet S on which an image has been formed in the image forming unit 5 to the outside of the image forming apparatus 1, or conveys the sheet S again toward the image forming unit 5. The paper discharge unit 7 includes a pair of paper discharge rollers 71 and a paper discharge tray 72.

[0054] Of the transport path P1, the transport path P1 downstream of the fixing unit 6 is formed as a paper discharge path P1a. Paper discharge rollers 71 are configured to be able to discharge the sheet S transported from the fixing unit 6 along the paper discharge path P1a towards the outside of the device body 2. Paper discharge tray 72 is formed on the top surface of the device body 2, and supports the sheet S discharged to the outside of the device body 2 by the paper discharge rollers 71.

[0055] The discharge rollers 71 are configured to be rotatable in a discharge direction, which is a rotation direction when conveying the sheet S toward the discharge tray 72, and in a re-conveyance direction, which is a rotation direction opposite to the discharge direction. The image forming apparatus 1 has a re-conveyance path P2 that guides the sheet S, which has been conveyed along the conveyance path P1 and passed through the fixing device 6, to the conveyance path P1 upstream of the registration rollers 34 in the sheet conveyance direction.

[0056] The re-conveying path P2 branches off from the discharge path P1a at a branching point Pb located between the fixing unit 6 and the discharge roller 71, then extends forward between the image forming unit 5 and the paper feed tray 30, and merges with the conveying path P1 at a junction point Pa located between the conveying roller pair 33 and the registration roller pair 34.

[0057] The sheet S conveyed from the fixing unit 6 to the paper discharge unit 7 can be conveyed again to the image forming unit 5 via a re-conveyance path P2 by rotating the paper discharge roller 71 in the re-conveyance direction. The sheet S conveyed to the re-conveyance path P2 by the paper discharge roller 71 is conveyed toward the image forming unit 5 by a first re-conveyance roller pair 35 and a second re-conveyance roller pair 36 provided on the re-conveyance path P2.

[0058] The image forming apparatus 1 is capable of double-sided printing, in which a sheet S, on one side of which an image has been formed in the image forming unit 5, is transported again to the image forming unit 5 via a re-transport path P2, and an image is formed on the other side of the sheet S.

[0059] The paper discharge sensor unit 8 is disposed between the fixing unit 6 and the paper discharge roller 71 in the sheet transport direction. The paper discharge sensor unit 8 can detect the sheet S that has passed through the fixing unit 6.

[0060] The device main body 2 is disposed downstream of the fixing unit 6 in the sheet conveying direction, and is provided with a chute 22 that forms part of the paper discharge path P1a, which is the conveying path P1 downstream in the sheet conveying direction of the fixing unit 6. The chute 22 is provided rotatably between a path forming position where the paper discharge path P1a is formed, and a path opening position where the paper discharge path P1a is opened.

[0061] The chute 22 rotates as the rear cover 21 is opened and closed, and is located at a path forming position when the rear cover 21 is in a closed position, and is located at a path opening position when the rear cover 21 is in an open position.

[0062] The device body 2 is provided with a re-conveyance chute 23 located below the chute 22 and guiding the lower surface of the sheet S being conveyed along the re-conveyance path P2. The device body 2 also has a body frame 24 that covers the front, top, and rear of the heating unit 61 in the fixing device 6.

[0063] [Fuser] 2 and 3, the heating unit 61 of the fixing device 6 includes a heater 611, a holder 612, a stay 613, and a belt 614. The heater 611 is a flat plate-shaped heater extending in the left-right direction. The heater 611 has a first surface 611A and a second surface 611B opposite to the first surface 611A, and the first surface 611A is supported by the holder 612.

[0064] Holder 612 is made of, for example, a resin member, and has a guide surface 612a and a support wall 612b. Guide surface 612a contacts an inner circumferential surface 614a of belt 614 to guide belt 614. Support wall 612b has a support surface 612A that supports heater 611. Support surface 612A of support wall 612b abuts against first surface 611A of heater 611. Stay 613 is a member that supports holder 612, and is formed by bending a plate material that is more rigid than holder 612, such as a steel plate, into a generally U-shaped cross section.

[0065] The belt 614 is an endless belt that is heat-resistant and flexible, and includes 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 disposed inside the belt 614. The belt 614 is configured to rotate around the heater 611, holder 612, and stay 613. An inner peripheral surface 614a of the belt 614 contacts the heater 611.

[0066] The pressure roller 62 has a metal shaft 62A and an elastic layer 62B that covers the shaft 62A. The pressure roller 62 is pressed against the heater 611 via a belt 614. The pressure roller 62 sandwiches the belt 614 between itself and the heater 611, thereby forming a nip portion NP for heating and pressurizing the sheet S. That is, the pressure roller 62 heats and pressurizes the sheet S together with the heater 611 at the nip portion NP.

[0067] The pressure roller 62 is configured to be rotationally driven by a driving force transmitted from a drive source provided in the image forming apparatus 1. When the pressure roller 62 is rotationally driven, the pressure roller 62 rotates the belt 614 by friction with the belt 614 or the sheet S sandwiched in the nip portion NP. As a result, the sheet S onto which the toner image has been transferred is transported between the pressure roller 62 and the heated belt 614, whereby the toner image is thermally fixed.

[0068] 4 and 5, the fixing unit 6 has a fixing frame 63. The fixing frame 63 supports a heating unit 61 and a pressure roller 62. The fixing frame 63 supports a heater 611. The fixing frame 63 may support the heater 611 indirectly via another member such as a holder 612, or may support the heater 611 directly. The main body frame 24 is located above the fixing frame 63.

[0069] In this embodiment, the fixing device 6 includes a heating unit 61 having a heater 611 and a belt 614, and a pressure roller 62, but the fixing device 6 can also be configured to include a heating roller with a built-in heater and a pressure roller pressed against the heating roller.Furthermore, the fixing device 6 can also 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.

[0070] [Shoot] 5 to 8 and 13, chute 22 is configured to be rotatable in the front-to-rear direction around rotation shaft 22a, and can be positioned at a path forming position (position shown in FIG. 8) by rotating forward, and at a path opening position (position shown in FIG. 13) by rotating backward. Chute 22 includes a guide surface 221, a cover 222, a rotation stop rib 223, and a guide rib 224.

[0071] The guide surface 221 is located downstream of the fixing unit 6 in the sheet conveying direction, and forms part of the conveying path P1 when the chute 22 is in the path forming position, and opens the conveying path P1 when the chute 22 is in the path opening position.

[0072] The cover 222 is formed of a plate-like member extending in the left-right direction. The left-right direction is an example of the width direction perpendicular to the sheet conveying direction. The cover 222 has a main body portion 222a facing in the front-rear direction and an extension portion 222b extending forward from the lower end of the main body portion 222a.

[0073] The rotation stop rib 223 is a rib member that protrudes forward from the approximate center in the left-right direction of the main body 222a of the cover 222, and has an abutment surface 223a at its front end.

[0074] The guide rib 224 is a rib member that extends in the sheet conveying direction of the sheet S conveyed along the re-conveying path P2, and protrudes downward and forward from the lower end of the cover 222. The guide rib 224 faces the re-conveying chute 23 in the up-down direction, and guides the upper surface of the sheet S conveyed along the re-conveying path P2. A plurality of guide ribs 224 are arranged at intervals in the left-right direction.

[0075] The guide rib 224 has a first guide rib 224a and a second guide rib 224b. The first guide rib 224a is located approximately in the center in the left-right direction, and the second guide rib 224b is located to the right of the first guide rib 224a. As shown in Fig. 6, the length L1 of the first guide rib 224a in the sheet conveying direction is smaller than the length L2 of the second guide rib 224b in the sheet conveying direction.

[0076] [Paper ejection sensor unit] As shown in FIGS. 8 and 9, the paper discharge sensor unit 8 includes an optical sensor 81, a substrate 82, an actuator 83, and a support frame 84.

[0077] The optical sensor 81 has a light-emitting element 811 that emits light and a light-receiving element 812 that can receive light emitted from the light-emitting element 811. The optical sensor 81 turns on when the light-receiving element 812 receives the light emitted from the light-emitting element 811, and turns off when the light-receiving element 812 does not receive the light emitted from the light-emitting element 811.

[0078] An optical sensor 81 is mounted on a substrate 82. The substrate 82 is attached to a support frame 84. By attaching the substrate 82 to the support frame 84, the optical sensor 81 is supported by the support frame 84.

[0079] 10, the actuator 83 has a shaft 830, a first lever 831, a second lever 832, and a third lever 833. The shaft 830 is a shaft member extending in the left-right direction. The shaft 830 is supported by the support frame 84 so as to be rotatable in a first direction W1 and a second direction W2 opposite to the first direction W1 about an axis X extending in the left-right direction. The shaft 830 is located below the conveying path P1.

[0080] The first lever 831 protrudes from the shaft 830 in a direction perpendicular to the direction of the axis X. The protruding direction of the first lever 831 is a direction below the shaft 830. The first lever 831 is configured to be able to come into contact with the rotation stop rib 223 of the chute 22.

[0081] The second lever 832 protrudes from the shaft 830 in a direction perpendicular to the direction of the axis X. The protruding direction of the second lever 832 is a direction downward from the shaft 830. The second lever 832 is configured to be able to block light emitted from the light emitting element 811 of the optical sensor 81. The second lever 832 is located to the left of the first lever 831 in the direction of the axis X.

[0082] The third lever 833 protrudes from the shaft 830 in a direction perpendicular to the direction of the axis X. The protruding direction of the third lever 833 is a direction above the shaft 830. The third lever 833 is located to the right of the first lever 831 in the direction of the axis X. The third lever 833 is disposed on the conveying path P1, and is configured to be able to come into contact with the sheet S being conveyed along the conveying path P1.

[0083] When the sheet S to be conveyed comes into contact with the third lever 833 arranged on the conveying path P1, the actuator 83 rotates about the axis X in a direction in which the third lever 833 retreats below the conveying path P1. The third lever 833 is biased by a spring 85 (see FIG. 9(b)) in a direction in which the third lever 833 rotates from a position where it retreats below the conveying path P1 toward a position where it is arranged on the conveying path P1.

[0084] The first direction W1 is the direction in which the third lever 833 of the actuator 83 rotates from a position where it is disposed on the conveying path P1 to a position where it is retracted below the conveying path P1. The second direction W2 is the direction in which the third lever 833 of the actuator 83 rotates from a position where it is retracted below the conveying path P1 to a position where it is disposed on the conveying path P1.

[0085] As shown in FIG. 11, the actuator 83 and the optical sensor 81 are located approximately in the center of the device body 2 in the width direction, and the actuator 83 does not extend to the left or right end portions of the device body 2.

[0086] 8 and 9, the support frame 84 is a frame member extending in the left-right direction, and supports the optical sensor 81 and the actuator 83 mounted on the substrate 82. The support frame 84 supports the optical sensor 81 and the actuator 83, thereby forming a unitized paper discharge sensor unit 8.

[0087] The support frame 84 has fixing holes 840 through which screws 86 are inserted, and the screws 86 inserted into the fixing holes 840 are threaded into bosses 632 (see FIG. 4) of the fixing frame 63, thereby attaching the support frame 84 to the fixing frame 63. The actuator 83 and the optical sensor 81 are attached to the fixing frame 63 via the support frame 84.

[0088] The support frame 84 has an upstream frame 841, a downstream frame 842, and an opening 843. The upstream frame 841, the downstream frame 842, and the opening 843 are arranged in the left-right direction at portions where the substrate 82 on which the optical sensor 81 is mounted and the second lever 832 of the actuator 83 are located.

[0089] The upstream frame 841 is disposed on the upstream side of the support frame 84 in the sheet conveying direction. The upstream frame 841 is located between the fixing frame 63 and the actuator 83 and the optical sensor 81 in the sheet conveying direction. By being interposed between the fixing frame 63 and the actuator 83 and the optical sensor 81, the upstream frame 841 can shield the heat from the heating unit 61 in the fixing device 6, thereby reducing the influence of heat on the actuator 83 and the optical sensor 81.

[0090] The downstream frame 842 is located on the opposite side of the actuator 83 from the upstream frame 841 in the sheet conveying direction. In other words, the optical sensor 81, the substrate 82, and the actuator 83 are located between the upstream frame 841 and the downstream frame 842 in the sheet conveying direction.

[0091] The opening 843 is located between the upstream frame 841 and the downstream frame 842 in the sheet conveying direction, on the side where the second lever 832 extends from the shaft 830 further than the actuator 83, that is, at a position diagonally rearward and downward than the actuator 83. The opening 843 communicates with the outside of the support frame 84. The substrate 82 is exposed to the outside through the opening 843 of the upstream frame 841.

[0092] On the other hand, the opening 843 of the support frame 84 is covered by the cover 222 of the chute 22 when it is positioned at the path forming position. In other words, the cover 222 closes the opening 843 of the support frame 84 when the chute 22 is positioned at the path forming position.

[0093] In this way, the substrate 82 is exposed to the outside through the opening 843, but the opening 843 is closed by the cover 222 of the chute 22. This makes it possible for the cover 222 to prevent external light from entering the support frame 84 through the opening 843, thereby reducing malfunction of the optical sensor 81 mounted on the substrate 82.

[0094] The support frame 84 has conveying ribs 844. The conveying ribs 844 protrude downward further than the upstream frame 841, and are arranged at intervals in the left-right direction. As shown in Fig. 5, the conveying ribs 844 face the re-conveying chute 23 in the up-down direction, and guide the upper surface of the sheet S conveyed along the re-conveying path P2.

[0095] 5, 6, and 8, the conveying rib 844 is located in front of the first guide rib 224a in the chute 22. The conveying rib 844 is disposed adjacent to the first guide rib 224a in the left-right direction, and guides the sheet S conveyed along the re-conveying path P2 together with the first guide rib 224a. The second guide rib 224b of the chute 22 is disposed farther away from the conveying rib 844 in the left-right direction than the first guide rib 224a.

[0096] The length L3 (see FIG. 6) of the conveying rib 844 in the sheet conveying direction is smaller than the length L2 of the second guide rib 224b in the chute 22. The length L1 of the first guide rib 224a and the length L3 of the conveying rib 844 are smaller than the length L2 of the second guide rib 224b, but by guiding the sheet S with the conveying rib 844 and the first guide rib 224a, it is possible to guide the sheet S in the same way as the second guide rib 224b. Furthermore, by making the length L1 of the first guide rib 224a smaller than the length L2 of the second guide rib 224b, it is possible to reduce the size of the chute 22.

[0097] Furthermore, since the support frame 84 is provided with a conveying rib 844 that guides the sheet S being conveyed along the re-conveying path P2, the support frame 84 can also serve as a rib that guides the sheet S, thereby reducing the number of parts.

[0098] [Actuator operation] The actuator 83 can rotate about the axis X to move to a first position, a second position, and a third position.

[0099] As shown in FIG. 8, the first position is a position where the first lever 831 of the actuator 83 contacts the contact surface 223a of the rotation stop rib 223 with the chute 22 positioned at the path forming position.

[0100] When the actuator 83 is moved to the first position, the second lever 832 is interposed between the light-emitting element 811 and the light-receiving element 812, and the light emitted from the light-emitting element 811 is blocked by the second lever 832 (see FIG. 8(a)). As the light from the light-emitting element 811 is blocked by the second lever 832, the light-receiving element 812 does not receive the light, and the optical sensor 81 is turned off.

[0101] When the actuator 83 is in the first position, the third lever 833 is located on the conveying path P1 (see FIG. 8B). When the third lever 833 is located on the conveying path P1, if the sheet S is conveyed downstream of the fixing unit 6 in the sheet conveying direction, the sheet S comes into contact with the third lever 833.

[0102] When the actuator 83 is in the first position and the first lever 831 is in contact with the rotation prevention rib 223, the rotation of the actuator 83 in the second direction W2 is restricted by the rotation prevention rib 223 (see FIG. 8(c)). When the actuator 83 is in the first position, the rotation of the actuator 83 in the first direction W1 is not restricted.

[0103] 12, the second position is a position where the first lever 831 is separated from the rotation stop rib 223 when the chute 22 is located at the path forming position. When the sheet S transported along the transport path P1 abuts against the third lever 833 with the chute 22 located at the path forming position, the actuator 83 in the first position rotates in the first direction W1 from the first position to the second position.

[0104] When the actuator 83 is moved to the second position, the second lever 832 moves forward and retreats from between the light-emitting element 811 and the light-receiving element 812, and the light emitted from the light-emitting element 811 is not blocked by the second lever 832 but is received by the light-receiving element 812 (see FIG. 12(a)). This turns on the optical sensor 81. The image forming apparatus 1 can detect that the sheet S has been conveyed downstream of the fixing unit 6 in the sheet conveying direction, for example, by detecting that the chute 22 is positioned at the path forming position and that the optical sensor 81 is turned on.

[0105] 4 and 12(a), the fixing frame 63 is formed in a shape recessed forward and has a recess 631 that does not interfere with the second lever 832 when the actuator 83 is in the second position. In other words, when the actuator 83 moves to the second position, the second lever 832 moves forward and is positioned in the recess 631, thereby preventing interference between the second lever 832 and the fixing frame 63. This allows the actuator 83 and the fixing frame 63 to be disposed close to each other in the front-to-rear direction, thereby enabling space saving in the device main body 2.

[0106] When the actuator 83 is in the second position, the third lever 833 is retracted below the conveying path P1 (see FIG. 12(b)). When the actuator 83 is in the second position, the first lever 831 is moved forward away from the rotation stop rib 223, and the contact between the first lever 831 and the rotation stop rib 223 is released (see FIG. 12(c)).

[0107] 13, the third position is a position where the chute 22 is in the path open position and the first lever 831 is spaced apart from the rotation stop rib 223. When the actuator 83 is in the first position, the chute 22 is in the path open position and the second lever 832 is spaced apart from the rotation stop rib 223, and the actuator 83 moves to the third position by rotating from the first position in the second direction W2 due to the biasing force of the spring 85.

[0108] When actuator 83 is in the third position, second lever 832 moves rearward and retreats from between light-emitting element 811 and light-receiving element 812, and light emitted from light-emitting element 811 is not blocked by second lever 832 and is received by light-receiving element 812 (see FIG. 13(a)). This turns on optical sensor 81. Image forming apparatus 1 can detect that rear cover 21 has moved to the open position, for example, by detecting that chute 22 is in the path open position and that optical sensor 81 has been turned on.

[0109] When the actuator 83 is in the third position, the third lever 833 is disposed on the transport path P1 (see FIG. 13(b)). When the actuator 83 is in the third position, the third lever 833 is positioned further forward than when the actuator 83 is in the first position.

[0110] 13(b), the main body frame 24 includes a restricting wall 241 that comes into contact with the third lever 833 when the actuator 83 moves to the third position. The restricting wall 241 comes into contact with the third lever 833 when the actuator 83 moves from the first position to the third position, restricting the rotation of the actuator 83 in the second direction W.

[0111] In this way, by restricting the rotation of the third lever 833 in the second direction W when the actuator 83 moves to the third position, it is possible to prevent the third lever 833 from moving beyond the third position in the second direction W2, and prevent the rotation stop rib 223 and the first lever 831 from losing contact when the chute 22, which is in the path opening position, rotates to the path forming position.

[0112] When the actuator 83 is moved to the third position, the chute 22 is positioned in the path open position, the anti-rotation rib 223 is separated rearward from the first lever 831, and the contact between the first lever 831 and the anti-rotation rib 223 is released (see Figure 13(c)).

[0113] In the image forming apparatus 1, the actuator 83, which can be moved to a first position, a second position, and a third position, and the optical sensor 81 are both attached to the fixing frame 63, which allows them to be placed in the center of the width direction of the device body 2, thereby preventing interference with parts such as gears that are placed at the ends of the device body 2 in the width direction. Furthermore, since the tolerance of the attachment positions of the actuator 83 and the optical sensor 81 can be reduced, it is possible to use an optical sensor 81 with a small gap between the light-emitting element 811 and the light-receiving element 812.

[0114] This allows the actuator 83 and the optical sensor 81 to be positioned while maintaining the size of the device main body 2, even if the fixing device 6 is enlarged by configuring the heating unit 61 of the fixing device 6 with a flat heater 611, for example.

[0115] Furthermore, by supporting the actuator 83 and the optical sensor 81 by the fixing frame 63 and providing the rotation prevention rib 223 on the chute 22, the actuator 83 can be made smaller, and even if the fixing unit 6 is enlarged, the actuator 83 and the optical sensor 81 can be arranged while maintaining the size of the device main body 2.

[0116] Furthermore, by configuring the actuator 83 to move to the second position by rotating in the first direction W1 and to move to the third position by rotating in the second direction W2, the anti-rotation rib 223 provided on the chute 22 can be configured simply.

[0117] Furthermore, by supporting the actuator 83 and the optical sensor 81 as a unit by the support frame 84 and then attaching it to the fixing frame 63, the actuator 83 and the optical sensor 81 can be made smaller and placed in the center in the width direction of the apparatus body 2. Furthermore, when replacing the heating unit 61 and the pressure roller 62, the actuator 83 and the optical sensor 81 supported by the support frame 84 can be easily removed from the fixing frame 63, making it possible to reuse the actuator 83 and the optical sensor 81.

[0118] [Second embodiment of chute and paper discharge sensor unit] The image forming apparatus 1 may be configured to include a chute 22A and a paper discharge sensor unit 8A as shown in FIG. 14, instead of the configuration including the chute 22 and the paper discharge sensor unit 8. As shown in FIG.

[0119] Chute 22A does not have rotation stop ribs 223, but does have pressing arms 225, and is different from chute 22, which has rotation stop ribs 223 but does not have pressing arms 225. Other configurations of chute 22A are the same as those of chute 22, so description thereof will be omitted.

[0120] The paper discharge sensor unit 8A differs from the paper discharge sensor unit 8 in that it has an actuator 83A instead of the actuator 83, and a support frame 84A instead of the support frame 84. The other configurations of the paper discharge sensor unit 8A are the same as those of the paper discharge sensor unit 8, so a description thereof will be omitted.

[0121] Actuator 83A differs from actuator 83, which does not have fourth lever 834, in that it has fourth lever 834. Other configurations of actuator 83A are similar to those of actuator 83, and therefore description thereof will be omitted.

[0122] Support frame 84A differs from support frame 84, which does not have anti-rotation ribs 845, in that it has anti-rotation ribs 845. Other configurations of support frame 84A are similar to those of support frame 84, and therefore description thereof will be omitted.

[0123] The pressing arm 225 of the chute 22A is an arm that extends from the chute 22A toward the actuator 83A, and has an extending portion 225a that extends from the cover 222 of the chute 22A toward the actuator 83A, and an engaging portion 225b that bends downward from the tip of the extending portion 225a. The pressing arm 225 is an example of a pressing member.

[0124] Fourth lever 834 of actuator 83A protrudes from shaft 830 in a direction perpendicular to the direction of axis X. The protruding direction of fourth lever 834 is, for example, a direction above shaft 830. Fourth lever 834 is configured to be able to engage with pressing arm 225. When chute 22A rotates from the path forming position to the path opening position, pressing arm 225 engages with fourth lever 834 and presses actuator 83A.

[0125] The rotation stop rib 845 of the support frame 84A is configured to be able to come into contact with the first lever 831 of the actuator 83A, and by coming into contact with the first lever 831, it restricts the actuator 83A from rotating in the second direction W2.

[0126] The actuator 83A can rotate about the axis X to move to a first position, a second position, and a third position.

[0127] 14(a), the first position is a position where the first lever 831 of the actuator 83A contacts the rotation stop rib 845 when the chute 22A is located at the path forming position. When the actuator 83A is moved to the first position, the second lever 832 is interposed between the light-emitting element 811 and the light-receiving element 812, and the optical sensor 81 is turned off. When the actuator 83A is moved to the first position, the third lever 833 is disposed on the conveying path P1, and when the sheet S is conveyed downstream of the fixing unit 6 in the sheet conveying direction, the sheet S contacts the third lever 833.

[0128] When the actuator 83A is in the first position and the first lever 831 is in contact with the rotation-stopping rib 845, the rotation of the actuator 83A in the second direction W2 is restricted by the rotation-stopping rib 845. When the actuator 83A is in the first position, the rotation of the actuator 83A in the first direction W1 is not restricted.

[0129] 14(b), the second position is a position where the first lever 831 is separated from the rotation stop rib 845 when the chute 22A is located at the path forming position. When the sheet S transported along the transport path P1 abuts against the third lever 833 with the chute 22A located at the path forming position, the actuator 83A in the first position rotates in the first direction W1 from the first position and moves to the second position.

[0130] When the actuator 83A is in the second position, the second lever 832 is moved forward and retracted from between the light-emitting element 811 and the light-receiving element 812, and the optical sensor 81 is in the ON state. When the actuator 83A is in the second position, the third lever 833 is retracted below the conveying path P1. When the actuator 83A is in the second position, the first lever 831 is moved forward away from the rotation stop rib 845, and the contact between the first lever 831 and the rotation stop rib 845 is released.

[0131] 14(c), the third position is a position where the first lever 831 and the rotation stop rib 845 are spaced apart when the chute 22A is in the path opening position. When the chute 22 rotates from the path forming position to the path opening position, the pressing arm 225 engages with the fourth lever 834 and presses the actuator 83A, which is in the first position, in the first direction W. This causes the actuator 83A to rotate from the first position in the first direction W and move to the third position. In other words, when the chute 22A rotates from the path forming position to the path opening position, the pressing arm 225 of the chute 22A presses the actuator 83A in the direction in which the actuator 83A moves from the first position to the third position.

[0132] In this way, when the chute 22A rotates from the path forming position to the path opening position, the actuator 83A is pressed by the pressing arm 225, so that the actuator 83A can be forcibly moved from the first position to the third position in conjunction with the rotation of the chute 22A from the path forming position to the path opening position.

[0133] Furthermore, since the pressing arm 225 is an arm that extends from the chute 22A toward the actuator 83A and engages with the fourth lever 834 of the actuator 83A, with a simple configuration, the actuator 83A can be moved from the first position to the third position in conjunction with the rotational movement of the chute 22A from the path forming position to the path opening position.

[0134] When the actuator 83A is in the third position, the second lever 832 moves forward and retreats from between the light-emitting element 811 and the light-receiving element 812, and the optical sensor 81 is turned on. When the actuator 83A is in the third position, the first lever 831 moves forward and away from the rotation-stopping rib 845, and the contact between the first lever 831 and the rotation-stopping rib 845 is released.

[0135] The amount of movement of actuator 83A in the third position in the first direction W1 from the first position is smaller than the amount of movement of actuator 83A in the second position in the first direction W1 from the first position. However, the amount of movement of actuator 83A in the third position in the first direction W1 from the first position may be the same as the amount of movement of actuator 83A in the second position in the first direction W1 from the first position. Furthermore, the amount of movement of actuator 83A in the third position in the first direction W1 from the first position may be larger than the amount of movement of actuator 83A in the second position in the first direction W1 from the first position. [Explanation of symbols]

[0136] 1. Image forming device 6 Fixing unit 8, 8A Paper ejection sensor unit 22, 22A Shoot 24 Main frame 61 Heating unit 62 Pressure roller 63 Fixing Frame 81 Optical Sensor 83, 83A Actuator 84, 84A support frame 222 Cover 223 Anti-rotation rib 224 Guide rib 224a First guide rib 224b Second guide rib 225 Pressing arm 241 Regulatory Wall 611 Heater 631 Recess 811 Light-emitting element 812 Photodetector 830 shaft 831 First Lever 832 Second Lever 833 Third Lever 834 4th Lever 841 Upstream Frame 842 downstream frame 843 Opening 844 Conveying rib L1 (first guide rib) length L2 (second guide rib) length S seat P1 transport route P1a paper output path W1 1st direction W2 Second direction

Claims

1. a fixing unit for fixing toner to a sheet, the fixing unit including a heater and a fixing frame for supporting the heater; a chute that is rotatable between a path forming position that forms a conveying path downstream of the fixing unit in a sheet conveying direction and a path opening position that opens the conveying path; an optical sensor having a light-emitting element that emits light and a light-receiving element that can receive light emitted from the light-emitting element; an actuator capable of contacting the rotation-stopping rib, the actuator having a shaft extending in a width direction perpendicular to the sheet conveying direction, a first lever protruding from the shaft and capable of contacting the rotation-stopping rib, and a second lever protruding from the shaft and capable of blocking light emitted from the light-emitting element of the optical sensor, the actuator being movable to a first position where the first lever contacts the rotation-stopping rib when the chute is positioned at the path forming position, a second position where the first lever and the rotation-stopping rib are spaced apart when the chute is positioned at the path forming position, and a third position where the first lever and the rotation-stopping rib are spaced apart when the chute is positioned at the path opening position; Equipped with The image forming apparatus is characterized in that the actuator and the optical sensor are supported by the fixing frame.

2. 2. The image forming apparatus according to claim 1, wherein the rotation stop rib is provided on the chute.

3. The image forming apparatus of claim 2, wherein the actuator has a third lever protruding from the shaft and positioned on the transport path, and when the chute is positioned at the path forming position, a sheet transported along the transport path abuts the third lever, causing the sheet to rotate from the first position in a first direction and move to the second position, and when the chute is positioned at the path opening position and the second lever and the rotation stop rib are separated, the chute rotates from the first position in a second direction opposite to the first direction and moves to the third position.

4. a main body frame covering the fixing unit; 4. The image forming apparatus according to claim 3, wherein the main body frame includes a restricting wall that abuts against the third lever when the actuator moves from the first position to the third position, thereby restricting rotation of the actuator in the second direction.

5. 5. The image forming apparatus according to claim 1, wherein the fixing frame has a recess that does not interfere with the second lever when the actuator is in the second position.

6. a support frame for supporting the actuator and the optical sensor; 6. The image forming apparatus according to claim 1, wherein the support frame is attached to the fixing frame, so that the actuator and the optical sensor are supported by the fixing frame.

7. 7. The image forming apparatus according to claim 6, wherein the support frame has an upstream frame disposed upstream in the sheet transport direction, the upstream frame being positioned between the fixing frame, the actuator, and the optical sensor.

8. the support frame has a downstream frame located on the opposite side of the actuator from the upstream frame side, and an opening is formed between the upstream frame and the downstream frame, the opening being on a side where the second lever extends further than the actuator, and communicating with the outside; 8. The image forming apparatus according to claim 7, wherein the chute has a cover that closes the opening of the support frame when the chute is positioned at the path forming position.

9. 9. The image forming apparatus according to claim 6, wherein the support frame includes a transport rib for guiding a sheet to be transported.

10. The chute has a plurality of guide ribs arranged at intervals in the width direction, the plurality of guide ribs include a first guide rib arranged adjacent to the transport rib in the width direction, and a second guide rib arranged farther from the transport rib in the width direction than the first guide rib, The image forming apparatus according to claim 9 , wherein the length of the first guide rib in the sheet conveying direction is smaller than the length of the second guide rib.

11. 2. The image forming apparatus according to claim 1, wherein the chute has a pressing member that presses the actuator in a direction in which the actuator moves from the first position to the third position when the chute rotates from the path forming position to the path opening position.

12. 12. The image forming apparatus according to claim 11, wherein the pressing member is an arm that extends from the chute toward the actuator and engages with the actuator when the chute rotates from the path forming position to the path opening position.

Images