Sheet conveying apparatus and image forming apparatus

Abstract

The present disclosure relates to a sheet conveying apparatus including a conveying section including a roller rotatable in a first rotation direction and a second rotation direction; a guide member configured to move between a first position and a second position; a drive source; a drive switching unit including an input unit, an output unit, and a switching unit; and a drive interruption unit configured to switch between a transmission state and a non-transmission state. The roller is configured to rotate by a drive force output from the output unit of the drive switching unit while the guide member moves between the first position and the second position. The present disclosure also relates to an image forming apparatus.

Description

Technical Field

[0001] The present invention relates to a sheet conveying apparatus for conveying sheet material and an image forming apparatus including the sheet conveying apparatus. Background Technology

[0002] In typical image forming apparatuses that form images on both surfaces of a sheet, once imaging on the first surface is complete, the sheet is turned and conveyed to a double-sided transport path for re-transfer to the image forming unit. In this case, a moving part capable of switching the sheet's transport path reliably conveys the sheet to the double-sided transport path. Recently, there has been a desire to increase the printing speed of image forming apparatuses during double-sided printing to improve productivity.

[0003] Japanese Patent Application Publication No. 2015-98399 discloses a printer comprising: an input gear; a planetary gear mechanism to which driving force is input from the input gear; a moving member driven by the driving force output from the planetary gear mechanism; and a discharge reverse conveyor roller. The rotation direction of the input gear is switched by a drive motor and a solenoid. The moving member can switch the sheet conveying path by moving between a first guide position and a second guide position, and the discharge reverse conveyor roller rotates back and forth to change the direction of the sheet.

[0004] However, in the printer described in Japanese Patent Application Publication No. 2015-98399, when the rotation direction of the input gear is switched, the moving part moves between a first guide position and a second guide position, but the driving force is not input to the discharge reverse conveyor roller while the moving part is moving. That is, the rotation direction of the discharge reverse conveyor roller is switched only after the moving part has completed its movement, and the switching of rotation direction takes time. As a result, productivity has been reduced. Summary of the Invention

[0005] According to one aspect of the present invention, a sheet conveying apparatus includes: a conveying section configured to convey a sheet, the conveying section including a roller rotatable in a first rotational direction and a second rotational direction opposite to the first rotational direction; a guiding member configured to guide the sheet and movable between a first position and a second position different from the first position; a drive source; a drive switching unit including an input unit and an output unit, the drive switching unit receiving a drive force from the drive source to the input unit, the output unit being configured to output the drive force to the roller; and a switching unit, the switching unit outputting a drive force transmitted from the input unit to the output unit in a first state, causing the roller to rotate in the second rotational direction, and the switching unit outputting a drive force transmitted from the input unit to the output unit in a second state different from the first state, causing the roller to rotate in the first rotational direction; and a drive interruption unit configured to switch between a transmission state in which the drive force transmitted from the switching unit is transmitted to the guiding member and a non-transmission state in which no drive force is transmitted to the guiding member. The roller is configured to rotate by a drive force output from the output unit of the drive switching unit while the guiding member moves between the first position and the second position.

[0006] Further features of the invention will become apparent from the following description of exemplary embodiments with reference to the accompanying drawings. Attached Figure Description

[0007] Figure 1 This is a schematic diagram showing the overall layout of the printer according to the first embodiment.

[0008] Figure 2A This is a schematic diagram illustrating sheet transport in single-sided printing mode.

[0009] Figure 2B This is a schematic diagram showing the sheet being transported along a first direction in a double-sided printing mode.

[0010] Figure 2C This is a schematic diagram showing the state of the sheet material changing from the first direction to the second direction in double-sided printing mode.

[0011] Figure 2D This is a schematic diagram showing the state of the sheet being conveyed along the second direction in double-sided printing mode.

[0012] Figure 3A This is a perspective view showing the drive mechanism.

[0013] Figure 3B This is another perspective view showing the drive mechanism.

[0014] Figure 4AThis is an exploded perspective view showing the reverse transmission unit.

[0015] Figure 4B This is another exploded perspective view showing the reverse transmission unit.

[0016] Figure 5A This is a rear view showing the reverse transmission unit.

[0017] Figure 5B This is a perspective view showing the reverse transmission unit.

[0018] Figure 5C This is a front view showing the reverse transmission unit.

[0019] Figure 5D This is another perspective view showing the reverse transmission unit.

[0020] Figure 6A This is a front view showing the reverse transmission unit during forward rotation.

[0021] Figure 6B This is a front view of the reverse transmission unit, omitting the reverse transmission switching gear.

[0022] Figure 6C This is a perspective view showing the reverse transmission unit during forward rotation.

[0023] Figure 6D This is a front view showing the reverse transmission unit during reversal.

[0024] Figure 6E This is a front view of the reverse transmission unit, omitting the reverse transmission switching gear.

[0025] Figure 6F This is a perspective view showing the reverse transmission unit during reversal.

[0026] Figure 7A It is a timing diagram showing the operating timing of the reverse conveyor roller, guide components, and clutch signals.

[0027] Figure 7B It is shown Figure 7A A perspective view of the drive mechanism during time period (b).

[0028] Figure 7C It is shown Figure 7A A perspective view of the drive mechanism during time period (c).

[0029] Figure 7D It is shown Figure 7A A perspective view of the drive mechanism during time period (d).

[0030] Figure 8A It is a timing diagram showing the operating timing of the reverse conveyor roller, guide components, and clutch signals.

[0031] Figure 8B It is shown Figure 8A A perspective view of the drive mechanism during time period (b).

[0032] Figure 8C It is shown Figure 8A A perspective view of the drive mechanism during time period (c).

[0033] Figure 9 This is a schematic diagram showing the overall layout of the printer according to the second embodiment.

[0034] Figure 10A This is a schematic diagram illustrating sheet transport in single-sided printing mode.

[0035] Figure 10B This is a schematic diagram showing the sheet being transported along a first direction in a double-sided printing mode.

[0036] Figure 10C This is a schematic diagram showing the state of the sheet material changing from the first direction to the second direction in double-sided printing mode.

[0037] Figure 10D This is a schematic diagram showing the state of the sheet being conveyed along the second direction in double-sided printing mode.

[0038] Figure 11A This is a perspective view showing the drive mechanism.

[0039] Figure 11B This is a front view showing the connection release unit in a non-transfer state.

[0040] Figure 11C This is a front view showing the connection release unit in the transmission state.

[0041] Figure 12A This is a perspective view showing the drive mechanism of the push solenoid in a de-energized state.

[0042] Figure 12B This is a perspective view showing the drive mechanism that switches the push solenoid from a de-energized state to an energized state.

[0043] Figure 12C This is a perspective view showing the drive mechanism with the push solenoid energized.

[0044] Figure 13A This is a timing diagram showing the operating timing of the reverse conveyor roller, guide components, and solenoid signals.

[0045] Figure 13B It is shown Figure 13A A schematic diagram of sheet transport during time period (b).

[0046] Figure 13C It is shown Figure 13A A schematic diagram of the sheet transport at time (c).

[0047] Figure 13D It is shown Figure 13A A schematic diagram of sheet transport during time period (d).

[0048] Figure 13E It is shown Figure 13A A schematic diagram of sheet transport during time period (e).

[0049] Figure 14 This is a schematic diagram showing the overall layout of a printer according to a third embodiment.

[0050] Figure 15A This is a schematic diagram illustrating sheet transport in single-sided printing mode.

[0051] Figure 15B This is a schematic diagram showing the sheet being transported along a first direction in a double-sided printing mode.

[0052] Figure 15C This is a schematic diagram showing the state of the sheet material changing from the first direction to the second direction in double-sided printing mode.

[0053] Figure 15D This is a schematic diagram showing the state of the sheet being conveyed along the second direction in double-sided printing mode.

[0054] Figure 16A This is a perspective view showing the drive mechanism with the clutch unit in a de-energized state.

[0055] Figure 16B This is a perspective view showing the drive mechanism when the clutch unit switches from a power-off state to a power-on state.

[0056] Figure 16C This is a perspective view showing the drive mechanism with the clutch unit energized.

[0057] Figure 17A This is a perspective view showing the drive mechanism according to the fourth embodiment.

[0058] Figure 17B This is another perspective view showing the drive mechanism according to the fourth embodiment.

[0059] Figure 18A This is an exploded perspective view showing the reverse transmission unit.

[0060] Figure 18B This is another exploded perspective view showing the reverse transmission unit.

[0061] Figure 19AThis is a perspective view showing the drive mechanism with the clutch unit in a de-energized state.

[0062] Figure 19B This is a perspective view showing the drive mechanism when the clutch unit switches from a power-off state to a power-on state.

[0063] Figure 19C This is a perspective view showing the drive mechanism with the clutch unit energized.

[0064] Figure 20A This is a perspective view showing the drive mechanism according to the fifth embodiment.

[0065] Figure 20B This is another perspective view showing the drive mechanism according to the fifth embodiment.

[0066] Figure 21A This is an exploded perspective view showing the reverse transmission unit.

[0067] Figure 21B This is another exploded perspective view showing the reverse transmission unit.

[0068] Figure 22A This is a front view showing the operation of the reverse transmission unit when the reverse transmission switching gear is rotating.

[0069] Figure 22B This is a rear view showing the operation of the reverse transmission unit when the reverse transmission switching gear is rotating.

[0070] Figure 22C This is a front view showing the operation of the reverse transmission unit when the reverse transmission switching gear is in a stopped state.

[0071] Figure 22D This is a rear view showing the operation of the reverse transmission unit when the reverse transmission switching gear is in a stopped state.

[0072] Figure 23A This is a perspective view showing the drive mechanism with the clutch unit in a de-energized state.

[0073] Figure 23B This is a perspective view showing the drive mechanism when the clutch unit switches from a power-off state to a power-on state.

[0074] Figure 23C This is a perspective view showing the drive mechanism with the clutch unit energized.

[0075] Figure 24A This is a perspective view showing the drive mechanism according to the sixth embodiment.

[0076] Figure 24B This is another perspective view showing the drive mechanism according to the sixth embodiment.

[0077] Figure 25A This is an exploded perspective view showing the reverse transmission unit.

[0078] Figure 25B This is another exploded perspective view showing the reverse transmission unit.

[0079] Figure 26A This is an exploded perspective view showing the planetary gear unit.

[0080] Figure 26B This is another exploded perspective view showing the planetary gear unit.

[0081] Figure 27A This is a front view showing the planetary gear unit when the planetary sun gear is rotating.

[0082] Figure 27B This is a rear view showing the planetary gear unit when the planetary sun gear is rotating.

[0083] Figure 27C This is a front view of a planetary gear unit with the planetary input gear and planetary sun gear omitted.

[0084] Figure 27D This is a rear view showing the planetary gear unit.

[0085] Figure 27E This is a front view of the planetary gear unit when the planetary sun gear is in a stopped state.

[0086] Figure 27F This is a rear view showing the planetary gear unit when the planetary sun gear is in a stopped state.

[0087] Figure 27G This is a front view of a planetary gear unit with the planetary input gear and planetary sun gear omitted.

[0088] Figure 27H This is a rear view showing the planetary gear unit.

[0089] Figure 28A This is a front view showing the drive mechanism with the solenoid de-energized.

[0090] Figure 28B This is a rear view showing the drive mechanism with the solenoid de-energized.

[0091] Figure 28C This is a front view showing the drive mechanism when the solenoid switches from a de-energized state to an energized state.

[0092] Figure 28D This is a rear view showing the drive mechanism when the solenoid switches from a de-energized state to an energized state.

[0093] Figure 29A This is a front view showing the drive mechanism with the solenoid energized.

[0094] Figure 29B This is a rear view showing the drive mechanism with the solenoid energized.

[0095] Figure 29C This is a front view showing the drive mechanism when the solenoid switches from an energized state to an de-energized state.

[0096] Figure 29D This is a rear view showing the drive mechanism when the solenoid switches from an energized state to an de-energized state.

[0097] Figure 30A This is a perspective view showing the drive mechanism of a first variant according to the sixth embodiment.

[0098] Figure 30B This is another perspective view showing the drive mechanism of the first variant according to the sixth embodiment.

[0099] Figure 31A This is a perspective view showing the reverse transmission unit according to a second variant of the sixth embodiment.

[0100] Figure 31B This is another perspective view showing the reverse transmission unit according to a second variant of the sixth embodiment. Detailed Implementation

[0101] First Embodiment

[0102] Overall configuration

[0103] First, a first embodiment of the present invention will be described. The printer 1, used as an image forming apparatus, is an electrophotographic laser beam printer that forms monochrome toner images. In the following description, the sheet S is the sheet on which the printer 1 forms an image, and includes, for example, paper, OHT sheets, etc.

[0104] like Figure 1 As shown, printer 1 includes a feed unit 10 for feeding stacked sheets S, an image forming unit 3 for forming an image on the sheets S, and a fixing unit 40 for fixing the image transferred to the sheets S. Furthermore, printer 1 includes a sheet discharge roller pair 50 capable of discharging the sheets S to a sheet discharge tray 54, and a reverse conveying roller pair 51 for turning the sheets S and conveying them to a double-sided conveying path R3. The sheet discharge roller pair 50 and the reverse conveying roller pair 51 constitute a conveying unit 510. The conveying unit 510, the guide member 53, and the drive mechanism 90, which will be described below, constitute a sheet conveying device 1000. The reverse conveying roller pair 51 includes a drive roller 51d that functions as a roller and a driven roller 51e that rotates following the drive roller 51d.

[0105] When an image forming job is output to printer 1, image forming unit 3 begins image forming processing based on image information input from an external computer or the like connected to printer 1. Image forming unit 3 includes a laser scanner 70, a processing cartridge 60 with a photosensitive drum 61, and a transfer roller 31. The processing cartridge 60 is configured to be detachable from the device body 2. A charging roller 62, a developing roller 63, and the like are disposed around the photosensitive drum 61. The photosensitive drum 61 and the transfer roller 31 form a transfer clamping section T1.

[0106] The laser scanner 70 illuminates the photosensitive drum 61 with a laser based on the input image information. In this case, the photosensitive drum 61 is pre-charged by the charging roller 62, and an electrostatic latent image is formed on the photosensitive drum 61 by illuminating it with a laser. Subsequently, the electrostatic latent image is developed by the developing roller 63, and a monochrome toner image is formed on the photosensitive drum 61.

[0107] In parallel with the image forming process described above, the sheet S is fed from the feed unit 10. The feed unit 10 includes a pull-out cartridge 10a attached to the device body 2 of the printer 1, an intermediate plate 13 supported by the cartridge 10a and movable up and down, a helical spring 12 that biases the intermediate plate 13 upward, a feed roller 11, and a separation pad 14.

[0108] When a feed command stored in cartridge 10a is issued, feed roller 11 begins to rotate. Simultaneously, intermediate plate 13 rotates upwards under the bias of helical spring 12, and the sheet S loaded on intermediate plate 13 comes into contact with feed roller 11. As a result, the sheet S is fed and separated one by one by separation pad 14.

[0109] Box 10a may omit the intermediate plate 13 and helical spring 12, and instead may be equipped with a mechanism for raising and lowering the feed roller 11. Furthermore, a separation roller or delay roller may be used instead of the separation pad 14.

[0110] The sheet S fed from the feed unit 10 is skewed by the alignment rollers 21 and conveyed according to the transfer timing at the transfer clamping part T1. In the sheet S, the toner image on the photosensitive drum 61 is transferred at the transfer clamping part T1 by applying an electrostatic load bias to the transfer rollers 31. Residual toner remaining on the photosensitive drum 61 is collected by a cleaning blade (not shown). A predetermined heat and pressure are applied to the sheet S, which has already had the toner image transferred, by the fixing film 41 and the pressure rollers 42 of the fixing unit 40, and the toner is melted and fixed. A heating element, such as a ceramic heater, is disposed inside the fixing film 41.

[0111] In a single-sided printing mode where the image is formed only on one side of the sheet S, the sheet S (on which the toner image is fixed by the fixing unit 40) is guided by the guide member 53 to the discharge conveyor path R1, and discharged to the sheet discharge tray 54 by the sheet discharge roller pair 50, as shown. Figure 2A As shown.

[0112] In a double-sided printing mode where images are formed on both sides of the sheet S, the sheet S with the image formed on the first surface is guided by the guide member 53 to the reverse transport path R2, such as... Figure 2B As shown. Then, the sheet S is first conveyed by the reverse conveyor rollers 51 in the first direction D1, and when the trailing edge of the sheet S passes the guide member 53, as... Figure 2C As shown, the reverse conveyor rollers 51 reverse, and the guide member 53 moves from the position shown by the dashed line to the position shown by the solid line. As a result, as... Figure 2D As shown, the sheet S is turned and conveyed in a second direction D2, opposite to the first direction D1, and guided by the guide member 53 to the double-sided conveying path R3. The first direction D1 is the direction that guides the sheet S to the outside of the device, and the second direction D2 is the direction that guides the sheet S to the inside of the device.

[0113] The sheet S is conveyed by the transfer roller pair 81 on the double-sided conveying path R3, and then conveyed again by the alignment roller pair 21 to the transfer clamping part T1. Then, an image is formed on the second surface of the sheet S at the transfer clamping part T1, and the sheet S is discharged by the sheet discharge roller pair 50 to the sheet discharge tray 54.

[0114] Drive mechanism

[0115] Next, the drive mechanism 90 for driving the sheet discharge roller pair 50, the reverse conveying roller pair 51, and the guide member 53 will be described. Figure 3A and 3B As shown, the drive mechanism 90 includes a drive motor M that rotates only in one direction, a discharge reverse transmission input gear 100, a reverse transmission unit 200, a discharge drive system 300, a reverse transmission drive system 400, a clutch drive system 500, and a clutch unit 600.

[0116] The discharge reverse transmission input gear 100 is driven by a drive source, a first drive source, and a drive motor M (used as a motor) via a gear train (not shown). The reverse transmission unit 200 is driven by the discharge reverse transmission input gear 100 and outputs driving force to the discharge drive system 300, the reverse transmission drive system 400, and the clutch drive system 500. The sheet discharge roller pair 50 is driven by the driving force transmitted to the discharge drive system 300. The reverse transmission roller pair 51 is driven by the driving force transmitted to the reverse transmission drive system 400. The driving force transmitted from the reverse transmission unit 200 to the clutch drive system 500 is transmitted to the clutch unit 600. The guide member 53 is driven by the driving force transmitted to the clutch unit 600.

[0117] Next, the reverse transmission unit 200, the discharge drive system 300, the reverse transmission drive system 400, the clutch drive system 500, and the clutch unit 600 will be described in more detail. The reverse transmission unit 200 includes a reverse transmission input gear 201, a reverse transmission switching gear 202, and a reverse transmission output gear 203. As will be described below, the reverse transmission unit 200 can output forward or reverse rotation (clockwise or counterclockwise rotation) by switching the rotation state of the reverse transmission switching gear 202.

[0118] The discharge drive system 300 includes a discharge stage gear 301 meshing with a reverse transmission input gear 201 and a discharge roller gear 302 meshing with the discharge stage gear 301. The discharge roller gear 302 is fixed to the drive shaft 50a of the sheet discharge roller pair 50, and the sheet discharge roller pair 50 rotates via the drive shaft 50a when the discharge roller gear 302 rotates.

[0119] The reverse conveying drive system 400 includes a reverse conveying stage gear 401 meshing with the reverse conveying output gear 203, a reverse conveying idler gear 402 meshing with the reverse conveying stage gear 401, and a reverse conveying roller gear 403 meshing with the reverse conveying idler gear 402. The reverse conveying roller gear 403 is fixed to the drive shaft 51a of the drive roller 51d of the reverse conveying roller pair 51, and when the reverse conveying roller gear 403 rotates, the reverse conveying roller pair 51 rotates via the drive shaft 51a. The reverse conveying idler gear 402 is coaxially arranged with the discharge stage gear 301.

[0120] The clutch drive system 500 includes a clutch idler wheel 501 that meshes with the reverse transmission switching gear 202 and a clutch stage gear 502 that meshes with the clutch idler wheel 501.

[0121] The clutch unit 600 includes a clutch input gear 601 that meshes with the clutch stage gear 502, a clutch retaining portion 602, a clutch output portion 604, and a guide switching lever 605. The clutch retaining portion 602 is held in place by a fixed rotation stop 603. The clutch output portion 604 is connected to the guide switching lever 605.

[0122] The clutch unit 600, which serves as a drive interruption unit, switches the connection state between the clutch input gear 601 and the clutch output section 604 according to the energization state of the clutch unit 600. That is, when the clutch unit 600 is in a de-energized state (non-transmission state), the clutch input gear 601 and the clutch output section 604 are not driven to connect. On the other hand, when the clutch unit 600 is in an energized state (transmission state), the clutch input gear 601 and the clutch output section 604 are driven to connect.

[0123] The guide switching lever 605, which rotates integrally with the clutch output section 604, has a contact portion 605a capable of contacting the contacted portion 53b of the guide member 53. The guide member 53 is biased in the direction of arrow SD1 by a return spring 52, which serves as a biasing unit. The return spring 52 is a torsion coil spring, one end of which contacts a component (not shown) and the other end of which contacts the guide member 53 to bias the guide member 53 in the direction of arrow SD1. The guide member 53 biased by the return spring 52 has an abutting portion 53a that abuts against a component (not shown). The abutting portion 53a abuts against the component (not shown), thereby holding the guide member 53 in a first position ( Figure 1 (The position indicated by the dashed line in the text).

[0124] When the guide switch lever 605 rotates, the contact portion 605a of the guide switch lever 605 presses against the abutment portion 53a of the guide member 53, and the guide member 53 moves in the opposite direction to the direction of arrow SD1, overcoming the biasing force of the return spring 52. As a result, the guide member 53 moves from the first position to the second position. Figure 1 (The solid line in the middle indicates the position).

[0125] That is, when the clutch unit 600 is energized, it can transmit the driving force from the reverse transmission switching gear 202 to the guide member 53, and when the power is off, it will not transmit the driving force from the reverse transmission switching gear 202 to the guide member 53.

[0126] Internal configuration of the reverse transmission unit

[0127] Next, we will refer to Figure 4A and 4B Describe the internal configuration of the reverse transmission unit 200. For example... Figure 4A and4B As shown, the reverse transmission unit 200, which serves as a drive switching unit, includes a reverse transmission input gear 201, a reverse transmission switching gear 202, a reverse transmission output gear 203, an internal idler gear 204, an internal stage gear 205, and a carrier unit 206. The reverse transmission input gear 201, serving as the input unit, is an input component that rotates by receiving the driving force transmitted from the aforementioned discharged reverse transmission input gear 100. The reverse transmission output gear 203, serving as the output unit, is an output component that outputs driving force to the reverse transmission drive system 400 to rotate the reverse transmission roller pair 51. The internal idler gear 204 and the internal stage gear 205 constitute two symmetrically arranged gear trains and are drive transmission components for transmitting drive from the reverse transmission input gear 201 to the reverse transmission output gear 203.

[0128] The carrier unit 206 includes an internal retainer 207 and a stop retainer 208, which are integrally connected and rotate. The internal retainer 207 rotatably supports the reverse transmission input gear 201 and includes a rotating shaft for a reverse transmission switching gear 202, a reverse transmission output gear 203, an internal idler gear 204, and an internal stage gear 205.

[0129] A stop retainer 208 holds a locking lever 209 and a pressing spring 210. The locking lever 209 is rotatably supported relative to the stop retainer 208 about a rotation axis 209c. The locking lever 209 includes a protrusion 209a capable of engaging with a hole 202a formed in the reverse transmission switching gear 202, and a locking portion 209b capable of engaging with a locked portion 201c of the reverse transmission input gear 201. The locking lever 209 is movable between an engaged position where the locking portion 209b engages with the locked portion 201c of the reverse transmission input gear 201 and a non-engaged position where the locking portion 209b does not engage with the locked portion 201c. The reverse transmission switching gear 202, the carrier unit 206, the locking lever 209, and the pressing spring 210 constitute a switching unit 310, which, depending on the state of the reverse transmission switching gear 202, causes the driving force transmitted from the reverse transmission input gear 201 to rotate forward and reverse and outputs driving force to the reverse transmission output gear 203.

[0130] The pressing spring 210 biases the locking lever 209 toward the engagement position. When the reverse transmission input gear 201 is locked by the locking lever 209 in the engagement position, the reverse transmission input gear 201 and the carrier unit 206 become one unit.

[0131] That is, in the first state, the locking lever 209, which serves as the engagement member, engages with the reverse transmission input gear 201, and therefore, the switching unit 310 rotates integrally with the reverse transmission input gear 201. In the second state, the locking lever 209 disengages from the reverse transmission input gear 201 in the switching unit 310. The reverse transmission switching gear 202 is configured to control the operation of the locking lever 209 according to its own rotation state.

[0132] Next, we will refer to Figures 5A to 5D Describe the meshing relationship of the corresponding gears in the reverse transmission unit 200. Figure 5A This is a rear view of the reverse transmission unit 200, omitting the reverse transmission output gear 203. Figure 5B This is a perspective view of the reverse transmission unit 200 with the reverse transmission output gear 203 omitted. Figure 5C This is a front view of the reverse transmission unit 200, omitting the reverse transmission input gear 201, the reverse transmission switching gear 202, and the carrier unit 206. Figure 5D This is a perspective view of the reverse transmission unit 200, omitting the reverse transmission input gear 201, the reverse transmission switching gear 202, and the carrier unit 206.

[0133] like Figure 5A and 5B As shown, the reverse transmission input gear 201 includes external teeth 201a that mesh with the aforementioned discharge reverse transmission input gear 100 and receive driving force, and internal teeth 201b that mesh with the internal idler gear 204, and is rotatably supported by the shaft portion of the internal retainer 207. The internal idler gear 204 and the internal stage gear 205 are composed of two symmetrically arranged gear trains, and are rotatably supported by rotating shafts 207a and 207b respectively provided in the internal retainer 207.

[0134] The internal gear 205 includes an integrally rotating first tooth 205a and a second tooth 205b, and the first tooth 205a meshes with the internal idler gear 204. Figure 5C and 5D As shown, the reverse transmission output gear 203 includes an external tooth 203a that outputs driving force to the reverse transmission drive system 400, an internal tooth 203b that meshes with the second tooth 205b of the internal stage gear 205, and a hole through which the shaft inserted into the internal retainer 207 passes. Furthermore, the reverse transmission output gear 203 is rotatably supported by the shaft portion of the internal retainer 207. The internal idler gear 204 meshes with the internal tooth 201b of the reverse transmission input gear 201, and the first tooth 205a of the internal stage gear 205 meshes with the internal idler gear 204. Moreover, when the second tooth 205b of the internal stage gear 205 meshes with the internal tooth 203b of the reverse transmission output gear 203, the driving force is sequentially transmitted from the reverse transmission input gear 201 to the reverse transmission output gear 203.

[0135] In the reverse conveying unit 200 configured as described above, driving force is transmitted from the discharge reverse conveying input gear 100 to the external teeth 201a of the reverse conveying input gear 201, and the gear receives driving force to rotate in one direction along the direction of arrow RD1. Additionally, the reverse conveying roller gear 403, which rotates the reverse conveying roller pair 51, is driven via the reverse conveying drive system 400 through the external teeth 203a of the reverse conveying output gear 203, and when the rotation direction of the reverse conveying output gear 203 changes, the reverse conveying roller pair 51 also follows and changes its rotation direction.

[0136] Reverse transmission unit drive switching operation

[0137] Next, we will refer to Figures 6A to 6F Describe the operation of switching the rotation direction of the reverse transmission output gear 203 of the reverse transmission unit 200. Figure 6A This is a front view of the reverse transmission unit 200 during forward rotation. Figure 6B This is a front view of the reverse transmission unit 200 when the reverse transmission switching gear 202 is rotating forward, omitting the reverse transmission unit 200. Figure 6C This is a perspective view of the reverse transmission unit 200 during forward rotation, omitting the reverse transmission input gear 201, the reverse transmission switching gear 202, and the carrier unit 206. Figure 6D This is a front view of the reverse transmission unit 200 during reversal. Figure 6E This is a front view of the reverse transmission unit 200 when the reverse transmission switching gear 202 is reversed. Figure 6F This is a perspective view of the reverse transmission unit 200 when the reverse transmission input gear 201, the reverse transmission switching gear 202, and the carrier unit 206 are reversed.

[0138] In the following text, the state of the reverse transmission unit 200 when the reverse transmission output gear 203 rotates in the direction of arrow RD2, which is the same as the direction of arrow RD1, which is the direction of rotation of the reverse transmission input gear 201, is referred to as the forward rotation time or forward rotation state. Conversely, the state of the reverse transmission unit 200 when the reverse transmission output gear 203 rotates in the direction of arrow RD3, which is opposite to the direction of arrow RD1, which is the direction of rotation of the reverse transmission input gear 201, is referred to as the reverse rotation time or reverse rotation state.

[0139] First, such as Figure 6A and 6BAs shown, consider a state where the reverse transmission switching gear 202 can rotate freely without external restriction. In this case, the locking lever 209 is in the engaged position, where the locking portion 209b engages with the locked portion 201c of the reverse transmission input gear 201 via the pressing spring 210. Therefore, the locking lever 209 rotates integrally with the reverse transmission input gear 201 in the direction of arrow RD1. Furthermore, since the protrusion 209a of the locking lever 209 engages with the hole 202a of the reverse transmission switching gear 202, the freely rotatable reverse transmission switching gear 202 also rotates integrally with the reverse transmission input gear 201 in the direction of arrow RD1.

[0140] Since the locking lever 209 is held by the stop retainer 208, the inner retainer 207, which is integrated with the stop retainer 208, also rotates in the direction of arrow RD1. Because no relative displacement occurs between the inner retainer 207 and the reverse transmission input gear 201, the inner idler gear 204, which is rotatably supported by the inner retainer 207, remains in a stopped (fixed) state relative to the inner retainer 207. Similarly, because no relative displacement occurs between the inner idler gear 204 and the inner retainer 207, the inner stage gear 205, which is rotatably supported by the inner retainer 207, also remains in a stopped (fixed) state relative to the inner retainer 207.

[0141] Therefore, the internal stage gear 205, together with the reverse transmission input gear 201, the reverse transmission switching gear 202, and the carrier unit 206, revolves around the rotation axis 201d of the reverse transmission input gear 201 in the same direction as arrow RD1. The rotation input to the reverse transmission input gear 201 in the direction of arrow RD1 is transmitted to the reverse transmission output gear 203 via the internal idler gear 204 and the internal stage gear 205, which revolve in the same direction when the reverse transmission input gear 201 and the carrier unit 206 rotate together. That is, as... Figure 6C As shown, the reverse transmission output gear 203 receives the driving force from the internal stage gear 205, which revolves in a fixed state relative to the internal retainer 207, to the internal teeth 203b. Therefore, the reverse transmission output gear 203 rotates in the direction of the rotating arrow RD2, which is the same direction as the arrow RD1, and outputs a rotational driving force.

[0142] That is, when the reverse transmission switching gear 202 rotates in the same direction and at the same speed as the reverse transmission input gear 201, the switching unit 310 (see...) Figure 4A In the first state, the switching unit 310 outputs the driving force transmitted from the reverse transmission input gear 201 to the reverse transmission output gear 203, causing the drive roller 51d of the reverse transmission roller pair 51 to rotate in the second rotation direction RR2 (see...). Figure 7B Rotate.

[0143] Next, as Figure 6D and 6E As shown, the state in which the reverse transmission switching gear 202 is externally restricted and its rotation is stopped is considered. In the initial state, as described above, the locking lever 209 is in the engaged position, wherein the locking portion 209b engages with the locked portion 201c of the reverse transmission input gear 201 via the pressing spring 210. When the locking lever 209 rotates together with the reverse transmission input gear 201 in this state, the protrusion 209a of the locking lever 209 moves along the edge of the hole 202a of the reverse transmission switching gear 202 in the stopped state in the direction of arrow M1.

[0144] As a result, Figure 6E As shown, the locking lever 209 rotates from the engaged position to the disengaged position around the rotation axis 209c, overcoming the biasing force of the pressing spring 210. Accordingly, the rotation of the reverse transmission input gear 201 in the direction of arrow RD1 is not transmitted to the stop retainer 208 and the inner retainer 207 that hold the locking lever 209, and the stop retainer 208 and the inner retainer 207 are in a stopped state.

[0145] On the other hand, the rotation input to the reverse transmission input gear 201 in the direction of arrow RD1 is transmitted to the reverse transmission output gear 203 via the internal idler gear 204 and the internal stage gear 205, which are rotatably supported by the stopped internal retainer 207. For example... Figure 6F As shown, since the internal idler gear 204 meshes with the internal teeth 201b of the reverse transmission input gear 201, the internal idler gear 204 rotates in the same rotational direction as the reverse transmission input gear 201. The internal stage gear 205 also rotates in the same direction as the reverse transmission output gear 203 because the internal stage gear 205 meshes with the internal teeth 203b of the reverse transmission output gear 203.

[0146] Since the internal idler gear 204 and the internal stage gear 205 rotate in opposite directions, the reverse transmission output gear 203 rotates in the direction of arrow RD3, which is opposite to the direction of arrow RD1, and outputs rotational driving force.

[0147] In other words, when the reverse transmission switching gear 202 is stopped by an external force, the switching unit 310 (see...) Figure 4A The system is in the second state and stopped. In this state, the switching unit 310 outputs the driving force transmitted from the reverse transmission input gear 201 to the reverse transmission output gear 203, causing the drive roller 51d of the reverse transmission roller pair 51 to rotate in the first rotation direction RR1 (see...). Figure 7D Rotate.

[0148] As described above, the reverse transmission output gear 203 is configured to rotate in the direction of arrow RD2 and in the direction of arrow RD3, which is opposite to the direction of arrow RD2, depending on whether the reverse transmission switching gear 202 is stopped by an external force.

[0149] Operation of reverse conveyor rollers and guide components

[0150] Next, the operation of the reverse conveyor roller pair 51 and the guide member 53 when the sheet S turns will be described. Figure 7A This is a timing diagram showing the operation timing of the reverse conveyor roller pair 51, guide member 53, and clutch unit 600 when the clutch unit 600 switches from a power-off state to a power-on state. Figure 7B It is shown Figure 7A Perspective view of drive mechanism 90 in time period (b). Figure 7C It is shown Figure 7A A perspective view of the drive mechanism 90 in time period (c). Figure 7D It is shown Figure 7A A perspective view of the drive mechanism 90 during time period (d).

[0151] Figure 8A This is a timing diagram of the signals from the reverse conveyor roller pair 51, the guide component 53, and the clutch unit 600 when the clutch unit 600 switches from an energized state to an de-energized state. Figure 8B It is shown Figure 8A Perspective view of drive mechanism 90 in time period (b). Figure 8C It is shown Figure 8A A perspective view of the drive mechanism 90 during time period (c). Figures 7B to 7D as well as Figure 8B and 8C In this diagram, the discharge drive system 300 and the sheet discharge roller pair 50 are omitted, and the rotation direction of each component is indicated by an arrow.

[0152] In the following description, for example, a printing operation is performed to drive the drive motor M, and the reverse transmission input gear 100 and the reverse transmission input gear 201 are rotated by the driving force of the drive motor M.

[0153] like Figure 7A and 7B As shown, when the clutch unit 600 is de-energized, the reverse conveying roller pair 51 moves along the second direction D2 (see...). Figure 2C The reverse conveyor roller pair 51 rotates in the direction of conveying sheet S. That is, the drive roller 51d of the reverse conveyor roller pair 51 rotates in the second rotation direction RR2. In this case, the rotation direction of the reverse conveyor roller pair 51 is defined as the reversal direction. The sheet S is moved along the first direction D1 (see...). Figure 2BThe rotation direction of the reverse conveyor roller pair 51 during conveying is defined as the forward rotation direction. In this case, the drive roller 51d of the reverse conveyor roller pair 51 rotates in the first rotation direction RR1, which is opposite to the second rotation direction RR2. Similarly, the rotation direction of the sheet discharge roller pair 50 when discharging the sheet S outside the device is defined as the forward rotation direction, and the rotation direction in the opposite direction is defined as the reverse rotation direction.

[0154] Since the drive connection between the clutch input gear 601 and the guide switching lever 605 is disengaged when the clutch unit 600 is de-energized, the rotation of the clutch input gear 601 is not transmitted to the guide switching lever 605. Therefore, the guide member 53 is positioned in a first position (denoted as Pos1 in the figure) by the biasing force of the return spring 52, and the sheet S conveyed by the fixing unit 40 can be guided toward the sheet discharge roller pair 50. The sheet discharge roller pair 50 rotates in the forward direction. That is, the clutch unit 600 is de-energized when performing single-sided printing mode and when discharging the sheet S in double-sided printing mode.

[0155] When the sheet S is conveyed to the reverse conveying path R2 in double-sided printing mode, the signal of the clutch unit 600 switches from OFF (disconnected) to ON (connected). For example... Figure 7A and 7C As shown, when the signal of clutch unit 600 switches from OFF to ON, clutch unit 600 transitions from a de-energized state to an energized state. As a result, clutch input gear 601 and guide switching lever 605 are driven together. Guide switching lever 605 rotates due to the driving force transmitted from clutch input gear 601 via reverse transmission switching gear 202 and clutch drive system 500, moving guide member 53 from a first position to a second position (denoted as Pos2 in the figure). Furthermore, when guide member 53 rotates from the first position to the second position, the rotation of reverse transmission switching gear 202 is unrestricted and rotates integrally with reverse transmission input gear 201. That is, the switching unit 310 of reverse transmission unit 200 (see...) Figure 4A The sheet discharge roller pair 50 remains in the first state. Therefore, the sheet discharge roller pair 50 remains rotating in the forward direction, and the reverse conveyor roller pair 51 remains rotating in the reverse direction.

[0156] After the guide member 53 moves to the second position, it abuts against a component (not shown), thus stopping its rotation. Because the driving force is continuously transmitted from the reverse transmission unit 200 to the guide switching lever 605, the guide member 53 remains in the second position. Figure 7D As shown, when the rotation of the guide component 53 stops, the guide switching rod 605, the clutch drive system 500, and the reverse transmission switching gear 202, which are linked to the guide component 53, stop simultaneously.

[0157] When the reverse transmission switching gear 202 stops, the aforementioned reverse transmission unit 200 switches from the forward rotation state to the reverse rotation state, and the rotation direction of the reverse transmission output gear 203 switches from the direction of arrow RD2 to the direction of arrow RD3 (see...). Figure 6C and 6F Therefore, the rotation direction of the reverse transmission drive system 400, which meshes with the reverse transmission output gear 203, and the rotation direction of the reverse transmission roller pair 51 are also switched in conjunction with each other. As a result, the reverse transmission roller pair 51 rotates in the forward direction to travel along the first direction D1 (see...). Figure 2B ) The sheet S is conveyed, that is, the sheet S is conveyed toward the outside of the printer 1.

[0158] In other words, based on the clutch unit 600 being energized and the guide member 53, which has moved from the first position to the second position, stopping at the second position, the switching unit 310 of the reverse transmission unit 200 (see...) Figure 4A The system transitions from the first state to the second state. When the clutch unit 600 is energized and the guide component 53 is stopped in the second position, the switching unit 310 of the reverse transmission unit 200 (see [link to relevant documentation]) switches from the first state to the second state. Figure 4A The sheet S is in the second state. As a result, the sheet S is guided by the guide member 53 located in the second position to the reverse conveying path R2, and is conveyed by the reverse conveying roller pair 51 in the first direction D1.

[0159] like Figure 8A and 8B As shown, when the clutch unit 600 is energized, as described above, the guide member 53 remains in the second position, and the reverse conveying roller pair 51 rotates in the forward direction. When the trailing edge of the sheet S passes the guide member 53, the signal of the clutch unit 600 switches from ON to OFF, and the clutch unit 600 changes from an energized state to an de-energized state. Therefore, the drive connection between the clutch input gear 601 and the guide switching lever 605 is released.

[0160] Since no driving force is input to the guide switching lever 605, the guide component 53 rotates from the second position to the first position by the biasing force of the return spring 52, as... Figure 8C As shown. When the guide component 53 begins to rotate from the second position to the first position, the rotation restriction of the reverse transmission switching gear 202 is released, allowing the reverse transmission switching gear to rotate freely. As a result, the reverse transmission unit 200 switches from a reverse state to a forward state, and the rotation direction of the reverse transmission output gear 203 changes from the direction of arrow RD3 to the direction of arrow RD2 (see...). Figure 6C and 6F ).

[0161] Therefore, the rotation direction of the reverse transmission drive system 400, which meshes with the reverse transmission output gear 203, and the rotation direction of the reverse transmission roller pair 51 also switch in conjunction with each other. As a result, the reverse transmission roller pair 51 rotates in the reverse direction to travel along the second direction D2 (see...). Figure 2C The sheet S is conveyed, that is, the sheet S is conveyed toward the interior of the printer 1. In other words, when the guide member 53 rotates between the first position and the second position, the reverse conveying roller pair 51 is configured to rotate by the driving force output from the reverse conveying output gear 203. Therefore, the sheet S is turned, and the sheet S is guided by the guide member 53 in the first position to the double-sided conveying path R3. Even when the guide member 53 is in the first position, the rotation of the reverse conveying switching gear 202 is not restricted because the clutch unit 600 is de-energized. Therefore, the sheet discharge roller pair 50 continues to rotate in the forward direction.

[0162] Effects of the first embodiment

[0163] As described above, the drive mechanism 90 according to this embodiment is a mechanism that uses the driving force of the drive motor M to drive the reverse conveyor roller pair 51 and the guide member 53. As described above, by using the drive mechanism 90 of this embodiment, the stopping state of the reverse conveyor roller pair 51 is shortened as much as possible when switching the rotation direction of the reverse conveyor roller pair 51 after the signal of the switching clutch unit 600. Since the switching time of the rotation direction of the reverse conveyor roller pair 51 is shortened and the sheet spacing during double-sided printing can be reduced, productivity can be improved.

[0164] More specifically, such as Figure 8A As shown, when the signal of the clutch unit 600 switches from ON to OFF, the guide member 53 rotates from the second position to the first position through the action of the reverse conveying unit 200 and the clutch unit 600. Furthermore, the rotation direction of the reverse conveying roller pair 51 switches from the forward direction to the reverse direction.

[0165] In this case, the switching operation of the rotation direction of the reverse conveyor roller pair 51 is performed in parallel with the operation of the guide member 53 rotating from the second position to the first position. Therefore, the switching operation of the rotation direction of the reverse conveyor roller pair 51 can be performed without waiting for the guide member 53 to finish rotating to the first position, so there is almost no stop time for the reverse conveyor roller in the switching operation of the rotation direction of the reverse conveyor roller pair 51. Therefore, the switching time of the rotation direction of the reverse conveyor roller pair 51 is shortened, and productivity can be improved.

[0166] When the signal of the clutch unit 600 switches from OFF to ON, the guide member 53 rotates from the first position to the second position through the action of the reverse conveying unit 200 and the clutch unit 600. When the guide member 53 rotates from the first position to the second position, the rotation of the reverse conveying switching gear 202 is unrestricted, and the reverse conveying switching gear 202 rotates integrally with the reverse conveying input gear 201. That is, the sheet discharge roller pair 50 remains rotating in the forward direction. Therefore, as... Figure 2A and 2B As shown, before the sheet S leaves the discharge roller pair 50 and is discharged outside the device, the guide member 53 can begin to move from the first position to the second position. Therefore, the timing of the signal for switching the clutch unit 600 can be advanced, and productivity can be improved.

[0167] Variations of the first embodiment

[0168] In this embodiment, the discharge stage gear 301 and the reverse conveying stage gear 401 are coaxially arranged, but they can be arranged on different shafts. In this embodiment, the discharge drive system 300 is included in the drive mechanism 90 by transmitting and driving the driving force from the reverse conveying input gear 201. However, the sheet discharge roller pair 50 can be driven from a drive motor (not shown) via another drive system.

[0169] In this embodiment, a torsion coil spring is used as the return spring 52 of the bias guide member 53, but other spring types such as compression springs, tension springs, or leaf springs can be used. In this embodiment, a configuration is used in which the guide member 53 is moved via the guide switching lever 605, but as another method, a method of transmitting the output unit of the clutch unit 600 to the guide member 53 via a belt, connecting rod, etc., can be used.

[0170] In this embodiment, the internal idler gear 204 and the internal stage gear 205 disposed inside the reverse conveying unit 200 are configured as two pairs of gears, but the present invention is not limited thereto. For example, a method of arranging only one pair of gears, the internal idler gear 204 and the internal stage gear 205, or a method of arranging three or more pairs of gears can be used.

[0171] Second Embodiment

[0172] Next, a printer 1A according to a second embodiment of the present invention will be described. The printer 1A differs from the printer of the first embodiment in that a reverse conveying three-roller 55 is provided instead of the sheet discharge roller pair 50 and the reverse conveying roller pair 51. Furthermore, the printer 1A differs from the printer of the first embodiment in that the discharge drive system 300 is omitted, a reverse conveying drive system 400A is provided instead of the reverse conveying drive system 400, and a guide member 56 is provided instead of the guide member 53 and the guide switching lever 605. Therefore, a configuration similar to the first embodiment will be described by omitting illustrations or by using the same reference numerals in the drawings.

[0173] Overall configuration

[0174] like Figure 9 As shown, the printer 1A, used as an image forming apparatus, includes a feeding unit 10 for feeding stacked sheets S, an image forming unit 3 for forming an image on the sheets S, and a fixing unit 40 for fixing and transferring the image onto the sheets S. Furthermore, the printer 1A includes a discharge reverse conveying three-roller 55 capable of discharging and turning the sheets S onto a sheet discharge tray 54 and conveying the sheets S onto a double-sided conveying path R3, and a guide member 56.

[0175] The discharge reverse conveying triple roller 55 includes a drive roller 55b that functions as a roller capable of both forward and reverse rotation, a discharge driven roller 55c that serves as a first driven roller that follows the rotation of the drive roller 55b, and a reverse conveying driven roller 55d that serves as a second driven roller that follows the rotation of the drive roller 55b. The discharge driven roller 55c is pressed against the drive roller 55b to form a discharge clamping portion N1, which serves as a first clamping portion. The reverse conveying driven roller 55d is pressed against the drive roller 55b to form a reverse conveying clamping portion N2, which serves as a second clamping portion. The guide member 56 is movable to... Figure 9 The first position indicated by the dashed line and Figure 9 The second position is shown by the solid line. The sheet conveying device 2000 consists of the discharge reverse conveying three rollers 55, the guide component 56, and the drive mechanism 90A described later.

[0176] In a single-sided printing mode where the image is formed on only one side of the sheet S, the sheet S, on which the toner image is fixed by the fixing unit 40, is guided by the guide member 56 located in the first position to the discharge conveyor path R1, as follows. Figure 10A As shown. Then, the sheet S is discharged to the sheet discharge tray 54 through the discharge clamping part N1.

[0177] In a double-sided printing mode where images are formed on both sides of the sheet S, the sheet S with the image formed on the first surface is guided by the guide member 56 located at the second position to the reverse conveying path R2, as shown. Figure 10BAs shown. Then, the sheet S is first conveyed by the reverse conveying clamping part N2 in the first direction D1, and when the trailing edge of the sheet S passes the guide member 56, as... Figure 10C As shown, the drive roller 55b reverses direction, and the guide member 56 moves from the second position shown by the dashed line to the first position shown by the solid line. As a result, as... Figure 10D As shown, the sheet S is turned and conveyed in a second direction D2 opposite to the first direction D1, and is guided by the guide member 56 located in the first position to the double-sided conveying path R3.

[0178] The sheet S is conveyed by the transfer roller pair 81 on the double-sided transfer path R3, and then conveyed again by the alignment roller pair 21 to the transfer clamping part T1. Then, an image is formed on the second surface of the sheet at the transfer clamping part T1, and the sheet S is discharged to the sheet discharge tray 54 through the discharge clamping part N1.

[0179] Drive mechanism

[0180] Next, the drive mechanism 90A for driving the discharge reverse conveying three-roller 55, which serves as a conveying section, and the guide member 56 will be described. For example... Figure 11A As shown, the drive mechanism 90A includes a drive motor M, a discharge reverse transmission input gear 100, a reverse transmission unit 200, a reverse transmission drive system 400A, a connection switching gear system 500A, and a connection release unit 700.

[0181] The discharge reverse conveying input gear 100 is driven by the drive motor M via a gear train (not shown). The reverse conveying unit 200 is driven by the discharge reverse conveying input gear 100 and outputs driving force to the reverse conveying drive system 400A and the connection switching gear system 500A. The discharge reverse conveying triple roller 55 is driven by the driving force transmitted to the reverse conveying drive system 400A. The reverse conveying roller pair 51 is driven by the driving force transmitted to the reverse conveying drive system 400A. The driving force transmitted from the reverse conveying unit 200 to the connection switching gear system 500A is transmitted to the connection release unit 700. The guide member 56 is driven by the driving force transmitted to the connection release unit 700.

[0182] Next, the reverse transmission unit 200, the reverse transmission drive system 400A, the connection switching gear system 500A, and the connection release unit 700 will be described in more detail. The reverse transmission unit 200 includes a reverse transmission input gear 201, a reverse transmission switching gear 202, and a reverse transmission output gear 203. As described in the first embodiment, the reverse transmission unit 200 can output forward or reverse rotation (clockwise or counterclockwise rotation) by switching the rotation state of the reverse transmission switching gear 202.

[0183] The reverse conveying drive system 400A includes a reverse conveying stage gear 401 that meshes with the reverse conveying output gear 203 and a reverse conveying roller gear 403 that meshes with the reverse conveying stage gear 401. The reverse conveying roller gear 403 is fixed to the drive shaft 55a of the drive roller 55b that discharges the reverse conveying triple roller 55, and when the reverse conveying roller gear 403 rotates, the drive roller 55b rotates via the drive shaft 55a.

[0184] The connecting switching gear system 500A includes a connecting switching idler wheel 503 and a connecting switching gear pair 504. The connecting switching idler wheel 503 meshes with the reverse transmission switching gear 202 and the connecting switching gear pair 504, and the rotation of the reverse transmission switching gear 202 is transmitted to the connecting release unit 700 via the connecting switching idler wheel 503 and the connecting switching gear pair 504.

[0185] The coupling release unit 700, used as a drive interruption unit, includes a push solenoid 701, a first ratchet 702, a second ratchet 703, a spring seat 704, and a coupling release spring 705. For example... Figure 11B and 11C As shown, the first ratchet 702 includes a first ratchet portion 702a. The second ratchet 703 has a second ratchet portion 703a facing the first ratchet portion 702a and is supported to be rotatable relative to the rotation axis 702b of the first ratchet 702.

[0186] A release spring 705 is disposed between the rotation shaft 702b of the first ratchet 702 and the spring seat 704, and the release spring 705 presses the rotation shaft 702b in the direction separating the first ratchet portion 702a from the second ratchet portion 703a. The spring seat 704 is fixed to a fixed component such as a frame of the device body 2. The push solenoid 701 is a push-type solenoid including a solenoid shaft 701a that can be pushed out when energized, and the solenoid shaft 701a is arranged to abut against the first ratchet 702. The push solenoid 701 and the solenoid shaft 701a constitute a contact separation mechanism 750 for engaging or disengaging the first ratchet portion 702a from the second ratchet portion 703a.

[0187] In the de-energized state where the push solenoid 701 is in a non-transmission state, such as Figure 11B As shown, the first ratchet portion 702a and the second ratchet portion 703a are separated from each other by the action of the coupling release spring 705. Therefore, the first ratchet 702 and the second ratchet 703 are not driven together. On the other hand, when the push solenoid 701 is in the energized state as a transmission state, as... Figure 11CAs shown, the first ratchet 702 is pressed toward the second ratchet 703 by the solenoid shaft 701a overcoming the biasing force of the coupling release spring 705. As a result, the first ratchet portion 702a and the second ratchet portion 703a engage with each other, and the first ratchet 702 and the second ratchet 703 are driven together.

[0188] The guide member 56 is biased by the return spring 52 in the direction of arrow SD1. The return spring 52 is a torsion coil spring, one end of which contacts a component (not shown), and the other end of which contacts the guide member 56 to bias the guide member 56 in the direction of arrow SD1. The guide member 56, biased by the return spring 52, abuts against a component (not shown) to hold in a first position. Figure 9 (The position indicated by the dashed line in the image).

[0189] The guide member 56 includes a guide switching gear 56a that meshes with the second ratchet 703, and rotates from the first position to the second position by the driving force transmitted from the second ratchet 703 when the push solenoid 701 is energized. Figure 9 (The position is indicated by the solid line in the middle).

[0190] Operation of the reverse conveyor three rollers and guide components

[0191] Next, we will refer to Figures 12A to 13E Describes the operation of discharging the reverse conveying three rollers 55 and the guide component 56 when the sheet S turns. Figure 12A This is a perspective view showing the drive mechanism 90A of the push solenoid 701 in the de-energized state. Figure 12B This is a perspective view showing the drive mechanism 90A when the push solenoid 701 is switched from a power-off state to a power-on state. Figure 12C This is a perspective view showing the drive mechanism 90A when the guide member 56 reaches the second position and abuts against a member (not shown). Figures 12A to 12C In the diagram, the direction of rotation for each component is indicated by an arrow.

[0192] In the following description, for example, a printing operation is performed to drive the drive motor M, and the reverse transmission input gear 100 and the reverse transmission input gear 201 are rotated by the driving force of the drive motor M.

[0193] like Figure 12AAs shown, when the push solenoid 701 is de-energized, the discharge reverse conveying three-roller 55 rotates in the direction shown. That is, the drive roller 55b of the discharge reverse conveying three-roller 55 rotates in the second rotation direction RR2, and the sheet S can be discharged through the discharge clamping part N1 of the discharge reverse conveying three-roller 55 toward the sheet discharge tray 54. In this case, the rotation direction of the discharge reverse conveying three-roller 55 is defined as the reverse direction. When the sheet S passes through the reverse conveying clamping part N2 of the discharge reverse conveying three-roller 55 along the first direction D1 (see... Figure 10B During conveying, the rotation direction of the discharge reverse conveying three-roller 55 is defined as the forward rotation direction. In this case, the drive roller 55b of the discharge reverse conveying three-roller 55 rotates in a first rotation direction RR1 opposite to the second rotation direction RR2 (see...). Figure 12C Rotate.

[0194] Since the drive connection between the first ratchet 702 and the second ratchet 703 is disengaged when the push solenoid 701 is de-energized, the rotation of the first ratchet 702 is not transmitted to the guide switching gear 56a. Therefore, the guide member 56 is positioned in the first position (denoted as Pos1 in the figure) by the biasing force of the return spring 52, and the sheet S can be guided toward the discharge conveying path R1 by the discharge clamping part N1, as shown. Figure 13B As shown, the push solenoid 701 is de-energized when executing single-sided printing mode and when ejecting the sheet S in double-sided printing mode.

[0195] In double-sided printing mode, when the sheet S is conveyed to the reverse conveying path R2, the signal of the push solenoid 701 switches from OFF to ON, such as... Figure 12B as well as Figure 13A and 13C As shown. When the signal of the push solenoid 701 switches from OFF to ON, the push solenoid 701 switches from a de-energized state to an energized state. As a result, the first ratchet 702 and the second ratchet 703 are driven together. The guide switching gear 56a rotates by the driving force transmitted from the second ratchet 703 to move the guide member 56 from the first position to the second position (represented as Pos2 in the figure). In addition, when the guide member 56 rotates from the first position to the second position, the rotation of the reverse transfer switching gear 202 is unrestricted, and the reverse transfer switching gear 202 rotates integrally with the reverse transfer input gear 201. That is, the discharge reverse transfer triple roller 55 is kept rotating in the reverse direction of conveying the sheet S to the outside of the device through the discharge clamping part N1.

[0196] After the guide member 56 moves to the second position, the guide member 56 abuts against (not shown) the member, thus stopping its rotation, as... Figure 13DAs shown. Because the driving force is continuously transmitted from the reverse transmission unit 200 to the guide switching gear 56a, the guide member 56 remains continuously in the second position. Figure 12C As shown, when the rotation of the guide component 56 stops, the connection release unit 700, the connection switching gear system 500A, and the reverse transmission switching gear 202, which are linked to the guide component 56, stop simultaneously.

[0197] When the reverse conveying switching gear 202 stops, the aforementioned reverse conveying unit 200 switches from a forward rotation state to a reverse rotation state, and the rotation direction of the reverse conveying output gear 203 switches from the direction of arrow RD2 to the direction of arrow RD3. Therefore, the rotation directions of the reverse conveying drive system 400A, which meshes with the reverse conveying output gear 203, and the discharge reverse conveying triple roller 55 also switch in conjunction with each other. As a result, the discharge reverse conveying triple roller 55 rotates in the forward direction, as... Figure 13E As shown. Consequently, the sheet S is guided by the guide member 56 located in the second position to the reverse conveying path R2, and conveyed in the first direction D1 by the reverse conveying clamping part N2 of the discharge reverse conveying three-roller 55, as shown. Figure 10B As shown.

[0198] like Figure 13E As shown, when the push solenoid 701 of the coupling release unit 700 is energized, as described above, the guide member 56 remains in the second position, and the discharge reverse conveying triple roller 55 rotates in the forward direction. When the trailing edge of the sheet S passes the guide member 56, the signal of the push solenoid 701 switches from ON to OFF, and the push solenoid 701 switches from the energized state to the de-energized state. As a result, the drive connection between the first ratchet 702 and the second ratchet 703 is released.

[0199] Since no driving force is input to the guide switching gear 56a, the guide member 56 rotates from the second position to the first position by the bias force of the return spring 52. When the guide member 56 begins to rotate from the second position to the first position, the rotation restriction of the reverse transmission switching gear 202 is released, and the reverse transmission switching gear can rotate freely. As a result, the reverse transmission unit 200 switches from the reverse state to the forward state, and the rotation direction of the reverse transmission output gear 203 switches from the direction of arrow RD3 to the direction of arrow RD2, as shown. Figure 12A As shown.

[0200] Therefore, the rotation directions of the reverse conveying drive system 400A, which meshes with the reverse conveying output gear 203, and the discharge reverse conveying triple roller 55 are also switched in conjunction with each other. As a result, the discharge reverse conveying triple roller 55 moves along the second direction D2 via the reverse conveying clamping part N2 (see...). Figure 10CThe sheet S rotates in the reverse direction, that is, it rotates in the opposite direction of conveying the sheet S toward the interior of the printer 1. In other words, when the guide member 56 rotates between the first and second positions, the discharge reverse conveying triple roller 55 is configured to rotate by the driving force output from the reverse conveying output gear 203. Therefore, the sheet S is turned, and the sheet S is guided by the guide member 56 in the first position to the double-sided conveying path R3. Even when the guide member 56 is in the first position, the rotation of the reverse conveying switching gear 202 is not restricted because the coupling release unit 700 is in the disconnected state. Therefore, the discharge reverse conveying triple roller 55 continues to rotate in the reverse direction.

[0201] Effects of the second embodiment

[0202] As described above, the drive mechanism 90A according to this embodiment is a mechanism that uses the driving force of the drive motor M to drive the discharge reverse conveyor roller 55 and the guide member 56. As described above, by using the drive mechanism 90A of this embodiment, the stopping state of the discharge reverse conveyor roller 55 can be minimized when switching the rotation direction of the discharge reverse conveyor roller 55 after switching the signal of the push solenoid 701. Since the time for switching the rotation direction of the discharge reverse conveyor roller 55 is shortened and the sheet spacing during double-sided printing can be reduced, productivity can be improved.

[0203] More specifically, when the signal for the push solenoid 701 switches from OFF to ON, the guide member 56 rotates from the first position to the second position via the action of the reverse conveying unit 200 and the coupling release unit 700. As the guide member 56 rotates from the first position to the second position, the rotation of the reverse conveying switching gear 202 is unrestricted and rotates integrally with the reverse conveying input gear 201. That is, the discharge reverse conveying triple roller 55 remains rotating in the reverse direction. Therefore, as... Figure 13C and 13D As shown, the guide member 56 can begin moving from the first position to the second position before the sheet S leaves the discharge clamping part N1 of the discharge reverse conveying three rollers 55 and is discharged outside the device. As a result, the timing of the signal for switching the push solenoid 701 can be advanced, and productivity can be improved.

[0204] When the signal for the push solenoid 701 switches from ON to OFF, the guide member 56 rotates from the second position to the first position through the action of the reverse conveying unit 200 and the coupling release unit 700. Furthermore, the rotation direction of the discharge reverse conveying triple roller 55 switches from the forward direction to the reverse direction.

[0205] In this case, the rotation direction switching operation of the discharge reverse conveyor roller 55 is performed in parallel with the operation of the guide member 56 rotating from the second position to the first position. Therefore, the rotation direction switching operation of the discharge reverse conveyor roller 55 can be performed without waiting for the guide member 56 to complete its rotation to the first position, so there is almost no stop time for the discharge reverse conveyor roller 55 during the rotation direction switching operation.

[0206] As described above, the time for switching the rotation direction of the discharge reverse conveying three rollers 55 is shortened, and the timing of the signal for switching the push solenoid 701 can be advanced, thus improving productivity.

[0207] Third Embodiment

[0208] Next, a printer 1B according to a third embodiment of the present invention will be described. The printer 1B differs from the printer of the first embodiment in that a reverse conveyor roller pair 57 is provided instead of a sheet discharge roller pair 50 and a reverse conveyor roller pair 51. Furthermore, the printer 1B differs from the printer of the first embodiment in that a guide member 58 is provided instead of a guide member 53 and a guide switching lever 605, and the clutch unit 600 is coaxially arranged with the rotation center of the guide member 58. Therefore, a configuration similar to the first embodiment will be described by omitting illustrations or by using the same reference numerals in the drawings.

[0209] Overall configuration

[0210] like Figure 14 As shown, the printer 1B, as an image forming apparatus, includes a feeding unit 10 for feeding stacked sheets S, an image forming unit 3 for forming an image on the sheets S, and a fixing unit 40 for fixing and transferring the image onto the sheets S. Furthermore, the printer 1B includes a discharge reverse conveyor roller pair 57 capable of discharging and turning the sheets S onto a sheet discharge tray 54 and conveying the sheets S to a double-sided conveyor path R3, and a guide member 58.

[0211] The discharge reverse conveyor roller pair 57, serving as a conveying unit, includes a drive roller 57b capable of rotating back and forth, and a driven roller 57c. The driven roller is pressed against the drive roller 57b to form a discharge reverse conveyor clamping part N3, which serves as a third clamping part. The driven roller 57c, acting as the third driven roller, rotates in tandem with the drive roller 57b, which acts as a roller. The guide member 58 is movable to a first position shown by the solid line in FIG. 15 and a second position shown by the dashed line in FIG. 15. The discharge reverse conveyor roller pair 57, the guide member 58, and the drive mechanism 90B, described later, constitute the sheet conveying device 3000.

[0212] In the case of a single-sided printing mode where the image is formed only on one side of the sheet S, such as Figure 15AAs shown, the sheet S is guided by the guide member 58 located in the first position to the discharge reverse conveying path R5, and discharged to the sheet discharge tray 54 through the discharge reverse conveying clamping part N3.

[0213] In a double-sided printing mode where images are formed on both sides of sheet S, the sheet S with the image formed on the first surface is guided by the guide member 58 located at the first position to the discharge reverse conveying path R5, such as... Figure 15A and 15B As shown. Then, the sheet S is first conveyed by the discharge reverse conveying clamping part N3 in the first direction D1. In this case, the drive roller 57b of the discharge reverse conveying roller pair 57 rotates in the first rotation direction RR1. When the trailing edge of the sheet S passes the guide member 58, as Figure 15C As shown, the drive roller 57b reverses direction, and the guide member 58 moves from the first position shown by the dashed line to the second position shown by the solid line. As a result, as... Figure 15D As shown, the sheet S is turned and conveyed in a second direction D2 opposite to the first direction D1, and is guided by the guide member 58 located in the first position to the double-sided conveying path R3. In this case, the drive roller 57b that discharges the reverse conveying roller pair 57 rotates in the second rotation direction RR2.

[0214] like Figure 14 As shown, the sheet S is conveyed by the transfer roller pair 81 on the double-sided transfer path R3, and then conveyed again by the alignment roller pair 21 to the transfer clamping part T1. Then, an image is formed on the second surface of the sheet S at the transfer clamping part T1, and the sheet S is discharged to the sheet discharge tray 54 through the discharge reverse transfer clamping part N3.

[0215] Drive mechanism

[0216] Next, the drive mechanism 90B for driving the discharge reverse conveyor roller pair 57 and the guide member 58 will be described. Figure 16A As shown, the drive mechanism 90B includes a drive motor M, a discharge reverse transmission input gear 100, a reverse transmission unit 200, a discharge reverse transmission drive system 400B, a connecting switching gear system 500B, and a clutch unit 600A.

[0217] The discharge reverse conveying input gear 100 is driven by a drive motor M via a gear train (not shown). The reverse conveying unit 200 is driven by the discharge reverse conveying input gear 100 and outputs driving force to the discharge reverse conveying drive system 400B and the connecting switching gear system 500B. The discharge reverse conveying roller pair 57 is driven by the driving force transmitted to the discharge reverse conveying drive system 400B. The driving force transmitted from the reverse conveying unit 200 to the connecting switching gear system 500B is transmitted to the clutch unit 600A. The guide member 58 is driven by the driving force transmitted to the clutch unit 600A.

[0218] Next, the reverse transmission unit 200, the reverse transmission drive system 400B, the connecting switching gear system 500B, and the clutch unit 600A will be described in more detail. The reverse transmission unit 200 includes a reverse transmission input gear 201, a reverse transmission switching gear 202, and a reverse transmission output gear 203. As described in the first embodiment, the reverse transmission unit 200 can output forward or reverse rotation (clockwise or counterclockwise rotation) by switching the rotation state of the reverse transmission switching gear 202.

[0219] The discharge reverse conveying drive system 400B includes a discharge reverse conveying stage gear 401A that meshes with the reverse conveying output gear 203 and a reverse conveying roller gear 403A that meshes with the discharge reverse conveying stage gear 401A. The reverse conveying roller gear 403A is fixed to the drive shaft 57a of the drive roller 57b of the discharge reverse conveying roller pair 57, and when the reverse conveying roller gear 403A rotates, the drive roller 57b rotates via the drive shaft 57a.

[0220] The connecting switching gear system 500B includes a connecting switching idler gear 503 and a connecting switching gear pair 504. The connecting switching idler gear 503 meshes with the reverse transmission switching gear 202 and the connecting switching gear pair 504, and the rotation of the reverse transmission switching gear 202 is transmitted to the clutch unit 600A via the connecting switching idler gear 503 and the connecting switching gear pair 504.

[0221] The clutch unit 600A, used as a drive interruption unit, includes a clutch input gear 601 that meshes with a connecting switching gear pair 504, a clutch retaining portion 602, and a clutch output portion 604. The clutch retaining portion 602 is held in place by a fixed rotation stop 603. The clutch output portion 604 engages with the D-shaped cutout rotating shaft 58a of the guide member 58 and rotates integrally with the guide member 58.

[0222] The clutch unit 600A switches the connection state between the clutch input gear 601 and the clutch output section 604 according to the energization state of the clutch unit 600A. That is, when the clutch unit 600A is de-energized, the clutch input gear 601 and the clutch output section 604 are not driven to connect. On the other hand, when the clutch unit 600A is energized, the clutch input gear 601 and the clutch output section 604 are driven to connect.

[0223] The guide member 58 is biased to a first position by a return spring 52. The return spring 52 is a torsion coil spring, one end of which contacts a component (not shown), and the other end contacts the guide member 58. The guide member 58 moves against the biasing force of the return spring 52 by a driving force transmitted from the clutch input gear 601. As a result, the guide member 58 moves from the first position to a second position. Figure 14 (The dashed line in the image indicates the position).

[0224] Operation of the reverse conveyor roller pair and guide components

[0225] Next, the operation of the reverse conveyor roller pair 57 and guide member 58 when the sheet S turns will be described. Figures 16A to 16C In the diagram, the direction of rotation of each component is indicated by an arrow. In the following description, for example, a printing operation is performed to drive the drive motor M, and the reverse transmission input gear 100 and the reverse transmission input gear 201 rotate under the driving force of the drive motor M.

[0226] like Figure 16A As shown, when the clutch unit 600A is de-energized, the discharge reverse conveyor roller pair 57 is discharged along the first direction D1 (see...). Figure 15A The sheet S is rotated in the direction of the conveying rollers. That is, the drive roller 51d of the reverse conveying roller pair 51 rotates in the first rotation direction RR1. In this case, the rotation direction of the discharge reverse conveying roller pair 57 is defined as the forward rotation direction. The sheet S is moved along the second direction D2 (see...). Figure 15C The rotation direction of the discharge reverse conveyor roller pair 57 during conveying is defined as the reverse direction. In this case, the drive roller 51d of the reverse conveyor roller pair 51 rotates in the second rotation direction RR2.

[0227] When the clutch unit 600A is de-energized, the drive connection between the clutch input gear 601 and the clutch output section 604 is disengaged, so the rotation of the clutch input gear 601 is not transmitted to the guide member 58. Therefore, the guide member 58 is positioned in a first position (denoted as Pos1 in the figure) by the biasing force of the return spring 52, and the sheet S can be guided towards the discharge reverse conveying path R5. The discharge reverse conveying roller pair 57 rotates in the forward direction. That is, the clutch unit 600A is de-energized when performing single-sided printing mode and when discharging the sheet S in double-sided printing mode.

[0228] When the sheet S is conveyed to the discharge reverse conveying path R5 in double-sided printing mode, the clutch unit 600A is initially de-energized, similar to the single-sided printing mode. Then, the sheet S is conveyed along the first direction D1 (i.e., towards the outside of the device) via the discharge reverse conveying clamping part N3 of the discharge reverse conveying roller pair 57. When the trailing edge of the sheet S passes the guide member 58, as... Figure 16B As shown, the signal of clutch unit 600A switches from OFF to ON, and clutch unit 600A changes from a de-energized state to an energized state. Therefore, clutch input gear 601 and clutch output section 604 are driven to connect.

[0229] The guide member 58 moves from the first position to the second position by overcoming the biasing force of the return spring 52 through the driving force transmitted from the clutch input gear 601. Furthermore, when the guide member 58 rotates from the first position to the second position, the rotation of the reverse transmission switching gear 202 is unrestricted, and the reverse transmission switching gear 202 rotates integrally with the reverse transmission input gear 201. That is, the discharge reverse transmission roller pair 57 remains rotating in the forward direction.

[0230] After the guide member 58 moves to the second position, it abuts against a component (not shown) and its rotation stops. Because the driving force is continuously transmitted from the reverse transmission unit 200 to the clutch output section 604, the guide member 58 remains in the second position. Figure 16C As shown, when the rotation of the guide component 58 stops, the clutch unit 600A, the connecting switching gear system 500B, and the reverse transmission switching gear 202, which are linked to the guide component 58, stop simultaneously.

[0231] When the reverse conveying switching gear 202 stops, the reverse conveying unit 200 switches from the forward rotation state to the reverse rotation state, and the rotation direction of the reverse conveying output gear 203 switches from the direction of arrow RD2 to the direction of arrow RD3. Therefore, the rotation directions of the discharge reverse conveying drive system 400B and the discharge reverse conveying roller pair 57, which mesh with the reverse conveying output gear 203, also switch in conjunction with each other. As a result, the discharge reverse conveying roller pair 57 moves along the second direction D2 (see...). Figure 15D The sheet S rotates in the reverse direction of the internal transport of the sheet S towards the printer 1. As a result, the sheet S is guided by the guide member 58 located in the second position to the double-sided transport path R3.

[0232] When the trailing edge of sheet S passes guide member 58, clutch unit 600A switches from energized to de-energized state, and drive mechanism 90B returns to its original position. Figure 16A The state shown.

[0233] Effects of the third embodiment

[0234] As described above, the drive mechanism 90B according to this embodiment is a mechanism that uses the driving force of the drive motor M to drive the discharge reverse conveyor roller pair 57 and the guide member 58. As described above, by using the drive mechanism 90B of this embodiment, the stopping state of the discharge reverse conveyor roller pair 57 can be minimized when switching the rotation direction of the discharge reverse conveyor roller pair 57 after switching the signal of the clutch unit 600A. Since the time for switching the rotation direction of the discharge reverse conveyor roller pair 57 is shortened and the sheet spacing during double-sided printing can be reduced, productivity can be improved.

[0235] Fourth embodiment

[0236] Next, the printer 1C according to the fourth embodiment of the present invention will be described (see below). Figure 1 The printer 1C differs from the printer of the first embodiment in that it provides a guide member 59 and a guide switching lever 605A instead of a guide member 53 and a guide switching lever 605. The printer 1C, used as an image forming apparatus, differs from the printer of the first embodiment in that it provides a reverse transport unit 200C instead of a reverse transport unit 200 and a clutch drive system 500C instead of a clutch drive system 500. Therefore, the same configuration as the first embodiment will be described by omitting figures or by using the same reference numerals in the drawings.

[0237] Drive mechanism

[0238] First, the drive mechanism 90C for driving the sheet discharge roller pair 50, the reverse conveying roller pair 51, and the guide member 59 will be described. Figure 17A and 17B As shown, the drive mechanism 90C includes a drive motor M, a discharge reverse transmission input gear 100, a reverse transmission unit 200A, a discharge drive system 300, and a reverse transmission drive system 400. The drive mechanism 90C also includes a clutch drive system 500C, a clutch unit 600B, and a drive switching motor M2.

[0239] The discharge reverse conveying input gear 100 is driven by the drive motor M via a gear train (not shown). The reverse conveying unit 200A is driven by the discharge reverse conveying input gear 100 and outputs driving force to the discharge drive system 300, the reverse conveying drive system 400, and the clutch drive system 500C. The sheet discharge roller pair 50 is driven by the driving force transmitted to the discharge drive system 300. The reverse conveying roller pair 51 is driven by the driving force transmitted to the reverse conveying drive system 400A. The driving force transmitted from the reverse conveying unit 200A to the clutch drive system 500C is transmitted to the clutch unit 600B. The guide member 59 is driven by the driving force transmitted to the clutch unit 600B.

[0240] Next, the reverse transmission unit 200A, the clutch drive system 500C, and the clutch unit 600B will be described in more detail. The reverse transmission unit 200A, which serves as a drive switching unit, includes a reverse transmission input gear 201A, a reverse transmission switching gear 202A, and a reverse transmission output gear 203. As will be described below, the reverse transmission unit 200A can output forward or reverse rotation (clockwise or counterclockwise rotation) by switching the rotation state of the reverse transmission switching gear 202. The reverse transmission switching gear 202A is configured to rotate in the same direction and at the same speed as the reverse transmission input gear 201A by the driving force of the drive switching motor M2, which serves as a second drive source.

[0241] With the same configuration as in the first embodiment, the discharge drive system 300 and the reverse conveying drive system 400 transmit driving force to the sheet discharge roller pair 50 and the reverse conveying roller pair 51, respectively.

[0242] The clutch drive system 500C includes a clutch idler gear 501 that meshes with a reverse transmission switching gear 202A, and a clutch stage gear 502 that meshes with the clutch idler gear 501 and the clutch input gear 601. The clutch drive system 500C includes a first clutch input gear 505, a second clutch input gear 506, and a torque limiter 507. The second clutch input gear 506 meshes with the clutch stage gear 502 and is driven to the first clutch input gear 505 via the torque limiter 507. The first clutch input gear 505 is driven by a drive switching motor M2 via a drive gear train (not shown).

[0243] The clutch unit 600B, used as a drive interruption unit, includes a clutch input gear 601 that meshes with a clutch stage gear 502, a clutch retaining portion 602, a clutch output portion 604, and a guide switching lever 605A. The clutch retaining portion 602 is held in place by a fixed rotation stop 603. The clutch output portion 604 is connected to the guide switching lever 605A.

[0244] The clutch unit 600B switches the connection state between the clutch input gear 601 and the clutch output section 604 according to the energization state of the clutch unit 600B. That is, when the clutch unit 600B is de-energized, the clutch input gear 601 and the clutch output section 604 are not driven to connect. On the other hand, when the clutch unit 600B is energized, the clutch input gear 601 and the clutch output section 604 are driven to connect.

[0245] The guide switching lever 605A, which rotates integrally with the clutch output section 604, has a slotted engagement portion 605Aa capable of engaging with the protrusion 59a of the guide member 59. The return spring 52A is a torsion coil spring, one end of which contacts a component (not shown), and the other end contacts the guide switching lever 605A to bias the guide member 59 in the direction of arrow SD1. Furthermore, the guide member 59, biased by the return spring 52A, is held in a first position ( Figure 1 The component (not shown) abuts at the position indicated by the dashed line in the diagram.

[0246] When the guide switch lever 605A rotates, the engaging portion 605Aa of the guide switch lever 605A presses against the protrusion 59a of the guide member 59, and the guide member 59 overcomes the biasing force of the return spring 52A and moves in the opposite direction to the direction of arrow SD1. As a result, the guide member 59 moves from the first position to the second position. Figure 1 (The position is indicated by the solid line in the middle).

[0247] Internal configuration of the reverse transmission unit

[0248] Next, we will refer to Figure 18A and 18B Describe the internal configuration of the reverse transmission unit 200A. For example... Figure 18A and 18B As shown, the reverse transfer unit 200A includes a reverse transfer input gear 201A, a reverse transfer switching gear 202A, a reverse transfer output gear 203, an internal idler gear 204, an internal stage gear 205, and an internal retainer 207A. The reverse transfer input gear 201A, serving as the input unit, is an input component that rotates by receiving the driving force transmitted from the aforementioned discharged reverse transfer input gear 100. The reverse transfer output gear 203 is an output component that outputs driving force to the reverse transfer drive system 400 that rotates the reverse transfer roller pair 51. The internal idler gear 204 and the internal stage gear 205 are composed of two symmetrically arranged gear trains and are drive transmission components for transmitting the drive from the reverse transfer input gear 201A to the reverse transfer output gear 203.

[0249] The internal retainer 207A rotatably supports the reverse transmission input gear 201A and includes a rotating shaft for a reverse transmission switching gear 202A, a reverse transmission output gear 203, an internal idler gear 204, and an internal stage gear 205. Furthermore, the internal retainer 207A and the reverse transmission switching gear 202A are integrally connected by engagement between a protrusion 207Aa in the internal retainer 207A and an engagement portion 202Aa in the reverse transmission switching gear 202A. The reverse transmission switching gear 202A, the internal retainer 207A, the internal idler gear 204, and the internal stage gear 205 constitute a switching unit 340, which outputs driving force to the reverse transmission output gear 203 by rotating forward and backward according to the state of the reverse transmission switching gear 202A using the driving force transmitted from the reverse transmission input gear 201A.

[0250] The meshing relationship between the reverse transmission input gear 201A, the reverse transmission output gear 203, the internal idler gear 204, and the internal stage gear 205 in the reverse transmission unit 200A is the same as that in the first embodiment. Figures 5A to 5D The description of the reverse transmission input gear 201A and the reverse transmission output gear 203, which are identical to those in the first embodiment, will be omitted. Furthermore, the relationship between the rotational states of the reverse transmission input gear 201A and the reverse transmission output gear 203, which depend on the operating state of the reverse transmission switching gear 202A, is the same as in the first embodiment.

[0251] When the driving force from the drive switching motor M2 is transmitted via the clutch drive system 500C, the reverse transmission switching gear 202A is in the operating state (rotating state). Furthermore, when the clutch unit 600B is energized, the guide member 59 stops, therefore, the clutch stage gear 502 is in a stopped state. As a result, the clutch second input gear 506, which meshes with the clutch stage gear 502, also stops, and through the action of the torque limiter 507, the drive is not transmitted from the clutch first input gear 505 to the clutch second input gear 506. Therefore, the reverse transmission switching gear 202A stops and does not transmit the driving force from the drive switching motor M2. When the clutch unit 600B is de-energized, the reverse transmission switching gear 202A is in the operating state, regardless of the position of the guide member 59.

[0252] That is, when the reverse transfer switching gear 202A is in the stopped state, the rotation of the reverse transfer input gear 201A is transmitted to the reverse transfer output gear 203 via the internal idler gear 204 and the internal stage gear 205. In this case, the reverse transfer output gear 203 rotates in the direction of arrow RD3 (that is, the rotation direction opposite to the rotation direction of the reverse transfer input gear 201A). In this case, the switching unit 340 is in the second state and outputs driving force to the reverse transfer output gear 203, causing the drive roller 51d of the reverse transfer roller pair 51 to rotate in the first rotation direction RR1 (see...). Figure 19C Rotate.

[0253] On the other hand, when the reverse transfer switching gear 202A is in an operating state (rotating state) driven by the driving force of the driving switching motor M2, the reverse transfer switching gear 202A rotates in the same direction and at the same speed as the reverse transfer input gear 201A. Therefore, it is equivalent to the reverse transfer input gear 201A and the reverse transfer switching gear 202A rotating as a unit. Therefore, the reverse transfer output gear 203 receives the rotational driving force from the internal stage gear 205, which is fixed to the internal retainer 207A and revolves simultaneously, thereby rotating in the same direction as the reverse transfer input gear 201A, that is, in the direction of arrow RD2. In this case, the switching unit 340 is in the first state and outputs a driving force to the reverse transfer output gear 203, causing the drive roller 51d of the reverse transfer roller pair 51 to rotate in the second rotational direction RR2 (see Figure 19A Rotate.

[0254] Operation of reverse conveyor rollers and guide components

[0255] Next, we will refer to Figures 19A to 19CThe operation of the reverse conveyor roller pair 51 and the guide member 59 is described when the sheet S is turned. Hereinafter, the state of the reverse conveyor unit 200A when the reverse conveyor output gear 203 rotates in the direction of arrow RD2 (which is the same as the direction of arrow RD1, which is the rotation direction of the reverse conveyor input gear 201A) is referred to as the forward rotation time or forward state. Conversely, the state when the reverse conveyor output gear 203 rotates in the direction of arrow RD3 (which is opposite to the direction of arrow RD1, which is the rotation direction of the reverse conveyor input gear 201A) is referred to as the reverse rotation time or reverse state. In the following description, for example, a printing operation is performed to drive the drive motor M, and the reverse conveyor input gear 100 and the reverse conveyor input gear 201A are rotated by the driving force of the drive motor M.

[0256] like Figure 19A As shown, when the clutch unit 600B is de-energized, the reverse transmission switching gear 202A rotates in the same direction and at the same speed as the reverse transmission input gear 201A, driven by the driving force of the drive switching motor M2 transmitted through the clutch drive system 500C. Therefore, the reverse transmission output gear 203 of the reverse transmission unit 200A is in a forward rotation state, and the reverse transmission roller pair 51 rotates along the second direction D2 (see...). Figure 2C It rotates in the conveying direction of sheet S, that is, it rotates in the reverse direction.

[0257] When the clutch unit 600B is de-energized, the drive connection between the clutch input gear 601 and the guide switching lever 605A is disengaged, so the rotation of the clutch input gear 601 is not transmitted to the guide switching lever 605A. Therefore, the guide member 59 is positioned in the first position (denoted as Pos1 in the figure) by the biasing force of the return spring 52A, and the sheet S conveyed by the fixing unit 40 can be guided toward the sheet discharge roller pair 50. The sheet discharge roller pair 50 rotates in the forward direction. That is, the clutch unit 600B is de-energized when performing single-sided printing mode and when discharging the sheet S in double-sided printing mode.

[0258] When the sheet is conveyed to the reverse conveying path R2 in double-sided printing mode, the signal of the clutch unit 600B switches from OFF to ON. For example... Figure 19BAs shown, when the signal of clutch unit 600B switches from OFF to ON, clutch unit 600B changes from a de-energized state to an energized state. Therefore, clutch input gear 601 and guide switching lever 605A are driven together. Guide switching lever 605A rotates by the driving force transmitted from clutch input gear 601 via reverse transmission switching gear 202A and clutch drive system 500C to move guide member 59 to a second position (shown as Pos2 in the figure). When guide member 59 rotates from the first position to the second position, the rotation of reverse transmission switching gear 202A is unrestricted, and reverse transmission switching gear 202A rotates integrally with reverse transmission input gear 201A. That is, sheet discharge roller pair 50 remains rotating in the forward direction.

[0259] After the guide member 59 moves to the second position, the guide member 59 abuts against (not shown) the component and its rotation stops. Since the driving force is continuously transmitted from the reverse transmission unit 200 to the guide switching lever 605A, the guide member 59 remains in the second position. Because the operation of the guide switching lever 605A is restricted, the torque limiter 507 does not transmit torque exceeding a predetermined value, and the clutch first input gear 505 rotates, but the drive system downstream of the clutch second input gear 506 stops. That is, as... Figure 19C As shown, when the rotation of the guide component 59 stops, the guide switching rod 605A, the clutch drive system 500C, and the reverse transmission switching gear 202A, which are linked to the guide component 59, stop simultaneously.

[0260] When the reverse transmission switching gear 202A stops, the aforementioned reverse transmission unit 200A switches from the forward rotation state to the reverse rotation state, and the rotation direction of the reverse transmission output gear 203 switches from the direction of arrow RD2 to the direction of arrow RD3 (see...). Figure 18A Therefore, the rotation direction of the reverse transmission drive system 400, which meshes with the reverse transmission output gear 203, and the rotation direction of the reverse transmission roller pair 51 are also switched in conjunction with each other. As a result, the reverse transmission roller pair 51 rotates in the forward direction to travel along the first direction D1 (see...). Figure 2B The sheet S is conveyed, that is, the sheet S is conveyed toward the outside of the printer 1. As a result, the sheet S is guided by the guide member 53 located at the second position to the reverse conveying path R2, and is conveyed by the reverse conveying roller pair 51 in the first direction D1.

[0261] When the clutch unit 600B is energized, as described above, the guide member 59 remains in the second position, and the reverse conveying roller pair 51 rotates in the forward direction. When the trailing edge of the sheet S passes the guide member 53, the signal of the clutch unit 600B switches from ON to OFF, and the clutch unit 600B changes from an energized state to a de-energized state. Therefore, the drive connection between the clutch input gear 601 and the guide switching lever 605A is released.

[0262] Since no driving force is input to the guide switching lever 605A, the guide component 59 rotates from the second position to the first position by the biasing force of the return spring 52A, as... Figure 19A As shown. When the guide member 59 begins to rotate from the second position to the first position, the rotation restriction of the reverse transmission switching gear 202A is released, and the reverse transmission switching gear 202A can rotate freely. As a result, the reverse transmission unit 200A switches from the reverse rotation state to the forward rotation state, and the rotation direction of the reverse transmission output gear 203 changes from the direction of arrow RD3 to the direction of arrow RD2 (see...). Figure 18A ).

[0263] Therefore, the rotation direction of the reverse transmission drive system 400, which meshes with the reverse transmission output gear 203, and the rotation direction of the reverse transmission roller pair 51 also switch in conjunction with each other. As a result, the reverse transmission roller pair 51 rotates in the reverse direction to travel along the second direction D2 (see...). Figure 2C The sheet S is conveyed towards the interior of the printer 1. Therefore, the sheet S is turned and guided by the guide member 59 in the first position to the double-sided conveying path R3. Even when the guide member 59 is in the first position, the rotation of the reverse conveying switching gear 202 is unrestricted because the clutch unit 600B is de-energized. Therefore, the sheet discharge roller pair 50 continues to rotate in the forward direction.

[0264] Effects of the fourth embodiment

[0265] As described above, the drive mechanism 90C according to this embodiment is a mechanism that uses the driving force of the drive motor M to drive the reverse conveyor roller pair 51 and the guide member 59. As described above, by using the drive mechanism 90C of this embodiment, the stopping state of the reverse conveyor roller pair 51 can be shortened as much as possible when switching the rotation direction of the reverse conveyor roller pair 51 after switching the signal of the clutch unit 600B. Since the time for switching the rotation direction of the reverse conveyor roller pair 51 is shortened and the sheet spacing during double-sided printing can be reduced, productivity can be improved.

[0266] Furthermore, compared to the reverse transfer unit 200 of the first embodiment, the reverse transfer unit 200A has a configuration that omits the locking lever 209 and the stop retainer 208. This is because the reverse transfer switching gear 202A is configured to rotate in the same direction and at the same speed as the reverse transfer input gear 201 by the driving force of the driving switching motor M2. As a result, the reverse transfer unit 200A can be miniaturized in the width direction (axial direction), and the drive mechanism 90C can also be miniaturized.

[0267] Variations of the fourth embodiment

[0268] In this embodiment, the rotation state of the reverse transmission switching gear 202A is switched to rotation or stop. However, the rotation direction of the reverse transmission output gear 203 can be switched by changing the rotation speed or rotation direction instead of stopping.

[0269] In addition, in this embodiment, the drive source for driving the reverse conveyor roller pair 51 is the same as the drive source for driving the guide member 59, but a configuration using two different drive sources can also be used.

[0270] Fifth Embodiment

[0271] Next, the printer 1D according to the fifth embodiment of the present invention will be described (see below). Figure 1 The printer 1D, as an image forming apparatus, differs from the printer of the fourth embodiment in that a reverse transfer unit 200B is provided instead of a reverse transfer unit 200A, and a clutch drive system 500D is provided instead of a clutch drive system 500C. Therefore, a configuration similar to that of the fourth embodiment will be described by omitting illustrations or by using the same reference numerals in the drawings.

[0272] Drive mechanism

[0273] First, the drive mechanism 90D for driving the sheet discharge roller pair 50, the reverse conveying roller pair 51, and the guide member 59 will be described. Figure 20A and 20B As shown, the drive mechanism 90D includes a drive motor M, a discharge reverse transmission input gear 100, a reverse transmission unit 200B, a discharge drive system 300, and a reverse transmission drive system 400. The drive mechanism 90D also includes a clutch drive system 500D, a clutch unit 600B, and a drive switching motor M2.

[0274] The discharge reverse conveying input gear 100 is driven by the drive motor M via a gear train (not shown). The reverse conveying unit 200B is driven by the discharge reverse conveying input gear 100 and outputs driving force to the discharge drive system 300, the reverse conveying drive system 400, and the clutch drive system 500D. The sheet discharge roller pair 50 is driven by the driving force transmitted to the discharge drive system 300. The reverse conveying roller pair 51 is driven by the driving force transmitted to the reverse conveying drive system 400A. The driving force transmitted from the reverse conveying unit 200B to the clutch drive system 500D is transmitted to the clutch unit 600B, which serves as a drive interruption unit. The guide member 59 is driven by the driving force transmitted to the clutch unit 600B.

[0275] Next, the reverse transmission unit 200B and the clutch drive system 500D will be described in more detail. The reverse transmission unit 200B, which serves as a drive switching unit, includes a reverse transmission input gear 201B, a reverse transmission switching gear 202B, and a reverse transmission output gear 203B. As will be described below, the reverse transmission unit 200B can output forward or reverse rotation (clockwise or counterclockwise rotation) by switching the rotation state of the reverse transmission switching gear 202B. The reverse transmission switching gear 202B is configured to rotate in the same direction and at the same speed as the reverse transmission input gear 201A by the driving force of the drive switching motor M2.

[0276] The clutch drive system 500D includes a clutch idler gear 501 that meshes with the reverse transmission switching gear 202B, and a clutch stage gear 502 that meshes with the clutch idler gear 501 and the clutch input gear 601. The clutch drive system 500C includes a clutch first input gear 505, a clutch second input gear 506, and a torque limiter 507. The clutch second input gear 506 meshes with the clutch idler gear 501 and is driven to the clutch first input gear 505 via the torque limiter 507. The clutch first input gear 505 is driven by the drive switching motor M2 via a drive gear train (not shown).

[0277] Internal configuration of the reverse transmission unit

[0278] Next, we will refer to Figures 21A to 22D Describe the internal configuration of the reverse transmission unit 200B. For example... Figure 21A and 21BAs shown, the reverse conveying unit 200B includes a reverse conveying input gear 201B serving as an input unit, a reverse conveying switching gear 202B serving as an output unit, a reverse conveying output gear 203B serving as an output unit, and an internal idler gear 204B. The reverse conveying input gear 201B is an input component that rotates by receiving the driving force transmitted from the aforementioned discharged reverse conveying input gear 100. The reverse conveying output gear 203B is an output component that outputs driving force to the reverse conveying drive system 400 that rotates the reverse conveying roller pair 51. The internal idler gear 204B includes a pair of symmetrically arranged gears and is a drive transmission component for transmitting the drive from the reverse conveying input gear 201B to the reverse conveying output gear 203B. The reverse conveying switching gear 202B includes the rotation shafts of the reverse conveying input gear 201B, the reverse conveying output gear 203B, and the internal idler gear 204B, and is configured to hold each gear.

[0279] An internal idler gear 204B is rotatably arranged on a pair of rotating shafts 202Ba disposed in the reverse transmission switching gear 202B, and meshes with a sun gear 201Ba disposed at the center of the reverse transmission input gear 201B. The internal idler gear 204B meshes with an internal gear 203Ba disposed in the reverse transmission output gear 203B. That is, the driving force of the reverse transmission input gear 201B is transmitted to the reverse transmission output gear 203B via the sun gear 201Ba, the pair of internal idler gears 204B, and the internal gear 203Ba. The reverse transmission switching gear 202B and the internal idler gear 204B constitute a switching unit 350, which outputs the driving force to the reverse transmission output gear 203B by rotating forward and backward according to the state of the reverse transmission switching gear 202B, based on the driving force transmitted from the reverse transmission input gear 201B.

[0280] Reverse transmission unit drive switching operation

[0281] Reference Figures 22A to 22D Describe the operation of switching the rotation direction of the reverse transmission output gear 203B of the reverse transmission unit 200B. Figure 22A and 22B These are front and rear views showing the operation of the reverse transmission unit 200B when the reverse transmission switching gear 202B is rotating. Figure 22C and 22D These are front and rear views showing the operation of the reverse transmission unit 200B when the reverse transmission switching gear 202B is in a stopped state. Figure 22A and 22C The reverse transmission output gear 203B is not shown, and Figure 22B and 22D The reverse transmission input gear 201B and the reverse transmission switching gear 202B are not shown.

[0282] like Figure 22A and 22B As shown, when the reverse transmission switching gear 202B is rotating, the driving force from the clutch first input gear 505 is transmitted to the reverse transmission switching gear 202B, and the reverse transmission switching gear 202B rotates in the same direction and at the same speed as the reverse transmission input gear 201B. In this case, it is equivalent to the reverse transmission switching gear 202B and the reverse transmission input gear 201B rotating as a unit. Since no relative displacement occurs between the reverse transmission switching gear 202B and the reverse transmission input gear 201B, the internal idler gear 204B, which is rotatably supported by the reverse transmission switching gear 202B, remains in a stopped (fixed) state relative to the reverse transmission switching gear 202B.

[0283] Therefore, the internal idler gear 204B, together with the reverse transmission input gear 201B and the reverse transmission switching gear 202B, revolves around the rotation axis of the reverse transmission input gear 201B in the same direction as arrow RD6. When the reverse transmission input gear 201B and the reverse transmission switching gear 202B rotate together, the rotation input to the reverse transmission input gear 201B in the direction of arrow RD6 is transmitted to the reverse transmission output gear 203B via the internal idler gear 204B revolving in the same direction. That is, as... Figure 22B As shown, the reverse transmission output gear 203B receives rotational driving force from the internal idler gear 204B, which revolves relative to the reverse transmission switching gear 202B when fixed, to the internal gear 203ba. As a result, the reverse transmission output gear 203B rotates in the direction of arrow RD7 (i.e., the same direction as arrow RD6) and outputs rotational driving force. In this case, the switching unit 350 is in the first state and outputs driving force to the reverse transmission output gear 203B, causing the drive roller 51d of the reverse transmission roller pair 51 to rotate in the second rotational direction RR2 (see...). Figure 23A Rotate.

[0284] like Figure 22C As shown, when the reverse transmission switching gear 202B is in a stopped state, the rotation of the reverse transmission input gear 201B in the direction of arrow RD6 is transmitted to the internal idler gear 204B, which meshes with the sun gear 201Ba. The internal idler gear 204B rotates about the rotation axis 202Ba in the direction of arrow RD9 (which is opposite to the direction of arrow RD6, which represents the rotation direction of the reverse transmission input gear 201B). Figure 22DAs shown, since the reverse transmission output gear 203B meshes with the internal idler gear 204B via the internal gear 203ba, the reverse transmission output gear 203B rotates in the direction of arrow RD8 (which is the same as the direction of arrow RD9, which is the rotation direction of the internal idler gear 204B). That is, the reverse transmission output gear 203B rotates in the direction of arrow RD8 (which is opposite to the direction of arrow RD6, which is the rotation direction of the reverse transmission input gear 201B). The rotational direction of the rotational driving force input from the reverse transmission input gear 201B changes between the sun gear 201ba and the internal idler gear 204B. In this case, the switching unit 350 is in the second state and outputs driving force to the reverse transmission output gear 203B, causing the drive roller 51d of the reverse transmission roller pair 51 to rotate in the first rotational direction RR1 (see...). Figure 23C Rotate.

[0285] Operation of reverse conveyor rollers and guide components

[0286] Next, we will refer to Figures 23A to 23C The operation of the reverse conveyor roller pair 51 and the guide member 59 is described when the sheet S turns. Hereinafter, the state of the reverse conveyor unit 200B when the reverse conveyor output gear 203B rotates in the direction of arrow RD8 (which is the same as the direction of arrow RD6, which is the rotation direction of the reverse conveyor input gear 201B) is referred to as the forward rotation time or forward state. The state when the reverse conveyor output gear 203B rotates in the direction of arrow RD8 (which is opposite to the direction of arrow RD6, which is the rotation direction of the reverse conveyor input gear 201B) is referred to as the reverse rotation time or reverse state. In the following description, for example, a printing operation is performed to drive the drive motor M, and the reverse conveyor input gear 100 and the reverse conveyor input gear 201B rotate by the driving force of the drive motor M.

[0287] like Figure 23A As shown, when the clutch unit 600B is de-energized, the reverse transmission switching gear 202B rotates in the same direction and at the same speed as the reverse transmission input gear 201B, driven by the driving force of the drive switching motor M2 transmitted through the clutch drive system 500D. Therefore, the reverse transmission output gear 203B of the reverse transmission unit 200B is in a forward rotation state, and the reverse transmission roller pair 51 rotates along the second direction D2 (see...). Figure 2C It rotates in the conveying direction of sheet S, that is, in the reverse direction.

[0288] When the clutch unit 600B is de-energized, the drive connection between the clutch input gear 601 and the guide switching lever 605A is disengaged, so the rotation of the clutch input gear 601 is not transmitted to the guide switching lever 605A. Therefore, the guide member 59 is positioned in the first position (denoted as Pos1 in the figure) by the biasing force of the return spring 52A, and the sheet S conveyed by the fixing unit 40 can be guided toward the sheet discharge roller pair 50. The sheet discharge roller pair 50 rotates in the forward direction. That is, the clutch unit 600B is de-energized when performing single-sided printing mode and when discharging the sheet S in double-sided printing mode.

[0289] When sheet S is conveyed to the reverse conveying path R2 in double-sided printing mode, the signal of clutch unit 600B switches from OFF to ON. For example... Figure 23B As shown, when the signal of clutch unit 600B switches from OFF to ON, clutch unit 600B changes from a de-energized state to an energized state. Therefore, the clutch input gear 601 and guide switching lever 605A are driven together. Guide switching lever 605A rotates via the driving force transmitted from clutch input gear 601 through reverse transmission switching gear 202A and clutch drive system 500D to move guide member 59 to a second position (shown as Pos2 in the figure). Furthermore, when guide member 59 rotates from the first position to the second position, the rotation of reverse transmission switching gear 202B is unrestricted, and reverse transmission switching gear 202B rotates integrally with reverse transmission input gear 201B. That is, the sheet discharge roller pair 50 remains rotating in the forward direction.

[0290] After the guide member 59 moves to the second position, it abuts against a component (not shown) and its rotation stops. Since the driving force is continuously transmitted from the reverse transmission unit 200 to the guide switching lever 605A, the guide member 59 remains in the second position. Because the operation of the guide switching lever 605A is restricted, the torque limiter 507 does not transmit torque exceeding a predetermined value, and the clutch first input gear 505 rotates, but the drive system downstream of the clutch second input gear 506 stops. Figure 23C As shown, when the rotation of the guide component 59 stops, the guide switching rod 605A, the clutch drive system 500D, and the reverse transmission switching gear 202B, which are linked to the guide component 59, stop simultaneously.

[0291] When the reverse transmission switching gear 202B stops, the aforementioned reverse transmission unit 200B switches from the forward rotation state to the reverse rotation state, and the rotation direction of the reverse transmission output gear 203B switches from the direction of arrow RD7 to the direction of arrow RD8 (see...). Figure 22B and 22CTherefore, the rotation directions of the reverse transmission drive system 400 and the reverse transmission roller pair 51, which mesh with the reverse transmission output gear 203B, also switch in conjunction with each other. As a result, the reverse transmission roller pair 51 rotates in the forward direction along the first direction D1 (see...). Figure 2B The sheet S is conveyed, that is, the sheet S is conveyed toward the outside of the printer 1. As a result, the sheet S is guided by the guide member 59 located in the second position to the reverse conveying path R2, and is conveyed by the reverse conveying roller pair 51 in the first direction D1.

[0292] When the clutch unit 600B is energized, as described above, the guide member 59 remains in the second position, and the reverse conveying roller pair 51 rotates in the forward direction. When the trailing edge of the sheet S passes the guide member 53, the signal of the clutch unit 600B switches from ON to OFF, and the clutch unit 600B changes from an energized state to a de-energized state. Therefore, the drive connection between the clutch input gear 601 and the guide switching lever 605A is released.

[0293] Since no driving force is input to the guide switching lever 605A, the guide component 59 rotates from the second position to the first position by the biasing force of the return spring 52A, as... Figure 23A As shown. When the guide component 59 begins to rotate from the second position to the first position, the rotation restriction of the reverse transmission switching gear 202A is released, and the reverse transmission switching gear 202A can rotate freely. As a result, the reverse transmission unit 200B switches from the reverse state to the forward state, and the rotation direction of the reverse transmission output gear 203B changes from the direction of arrow RD8 to the direction of arrow RD7 (see...). Figure 22B and 22D ).

[0294] Therefore, the rotation directions of the reverse transmission drive system 400 and the reverse transmission roller pair 51, which mesh with the reverse transmission output gear 203B, also switch in conjunction with each other. As a result, the reverse transmission roller pair 51 rotates in the reverse direction along the second direction D2 (see...). Figure 2C The sheet S is conveyed, that is, the sheet S is conveyed toward the interior of the printer 1. Therefore, the sheet S is turned and guided by the guide member 59 in the first position to the double-sided conveying path R3. Even when the guide member 59 is in the first position, the rotation of the reverse conveying switching gear 202B is not restricted because the clutch unit 600B is de-energized. Therefore, the sheet discharge roller pair 50 continues to rotate in the forward direction.

[0295] Effects of the fifth embodiment

[0296] As described above, the drive mechanism 90D according to this embodiment is a mechanism that uses the driving force of the drive motor M to drive the reverse conveyor roller pair 51 and the guide member 59. As described above, by using the drive mechanism 90D of this embodiment, the stopping state of the reverse conveyor roller pair 51 can be shortened as much as possible when switching the rotation direction of the reverse conveyor roller pair 51 after switching the signal of the clutch unit 600B. Since the time for switching the rotation direction of the reverse conveyor roller pair 51 is shortened and the sheet spacing during double-sided printing can be reduced, productivity can be improved.

[0297] Furthermore, compared to the reverse transfer unit 200A of the fourth embodiment, the reverse transfer unit 200B has a configuration that omits the internal retainer 207A and the internal stage gear 205. Therefore, the reverse transfer unit 200B can be configured simply, and the cost of the drive mechanism 90D can be reduced.

[0298] Sixth Embodiment

[0299] Next, the printer 1E according to the sixth embodiment of the present invention will be described (see below). Figure 9 The printer 1E, which serves as an image forming apparatus, has the same general configuration as the printer 1A according to the second embodiment, but the drive mechanism for driving the discharge reverse conveying three rollers 55 and the guide member 71 is different from the drive mechanism 90A of the second embodiment.

[0300] Drive mechanism

[0301] The drive mechanism 90E used to drive the discharge reverse conveying three rollers 55 and the guide component 71 will be described. For example... Figure 24A and 24B As shown, the drive mechanism 90E includes a drive motor M, a discharge reverse transmission input gear system 100A, a reverse transmission unit 200C, an intermediate rod 607, a solenoid unit 800, and a planetary gear unit 900.

[0302] The discharge reverse transmission input gear train 100A is driven by the drive motor M via a gear train (not shown). The reverse transmission unit 200C is driven by the discharge reverse transmission input gear train 100A and outputs driving force to the three-roller gear 404 and the planetary gear unit 900. The intermediate rod 607 is rotatably supported about the rotation axis 607a. An engagement portion 607b capable of engaging with the boss portion 71a of the guide member 71 is provided at one end of the intermediate rod 607, and a contact portion 607c capable of contacting the planetary output gear rod 903 (described later) is provided at the other end of the intermediate rod 607. The intermediate rod 607 is biased by the rod return spring 608, causing the contact portion 607c to press against the planetary output gear rod 903. The driving force transmitted to the planetary gear unit 900 is transmitted to the intermediate rod 607 via the planetary output gear rod 903, thus driving the guide member 71.

[0303] Next, the discharge reverse transmission input gear system 100A, the reverse transmission unit 200C, the solenoid unit 800, and the planetary gear unit 900 will be described in more detail. The discharge reverse transmission input gear system 100A includes a first discharge reverse transmission input gear 101, a second discharge reverse transmission input gear 102, and a third discharge reverse transmission input gear 103. The first discharge reverse transmission input gear 101 is driven by a drive motor M and meshes with the second discharge reverse transmission input gear 102. The third discharge reverse transmission input gear 103 has a recess 103a that engages with a protrusion 102a of the second discharge reverse transmission input gear 102, and rotates integrally with the second discharge reverse transmission input gear 102 through the engagement of the protrusion 102a and the recess 103a.

[0304] The reverse conveying unit 200C, used as a drive switching unit, includes a reverse conveying input gear 201, a reverse conveying switching gear 202, and a reverse conveying output gear 203. As described in the first embodiment, the reverse conveying unit 200C can output forward or reverse rotation (clockwise or counterclockwise rotation) by switching the rotation state of the reverse conveying switching gear 202. The three-roller gear 404 meshes with the reverse conveying output gear 203, and the three-roller gear 404 is fixed to the drive shaft 55a of the drive roller 55b of the discharge reverse conveying three-roller 55. Therefore, when the three-roller gear 404 rotates, the discharge reverse conveying three-roller 55 rotates.

[0305] The solenoid unit 800 includes a solenoid 801, a solenoid arm 801a, a solenoid rod 802, and an arm spring 803. When the solenoid 801 switches between a de-energized state and an energized state, the solenoid arm 801a rotates. The solenoid rod 802 is rotatably supported about a rotation axis 802c, and one end 802b engages with the solenoid arm 801a. A locking pawl 802a, capable of locking the locking pawl 902a of the planetary sun gear 902 (described later), is provided at the other end of the solenoid rod 802.

[0306] When solenoid 801 is de-energized, solenoid arm 801a is positioned under the bias of arm spring 803, and solenoid rod 802 is in a position where locking pawl 802a is separated from locked pawl 902a of planetary sun gear 902. When solenoid 801 is energized, solenoid arm 801a is driven by solenoid 801, and solenoid rod 802, which engages with solenoid arm 801a, rotates about rotation axis 802c. As a result, solenoid rod 802 is in the position where locking pawl 802a is locked to locked pawl 902a of planetary sun gear 902.

[0307] The solenoid unit 800 and the planetary gear unit 900 constitute a drive interruption unit 950, which can switch between a transmission state where the driving force transmitted from the switching unit 360 can be transmitted to the guide member 71 and a non-transmission state where the driving force is not transmitted to the guide member 71. As will be described below, the drive interruption unit 950 is in a non-transmission state when the solenoid 801 of the solenoid unit 800 is de-energized, and in a transmission state when the solenoid 801 is energized.

[0308] Internal configuration of the reverse transmission unit

[0309] Next, we will refer to Figure 25A and 25B Describe the internal configuration of the reverse transmission unit 200. For example... Figure 25A and 25B As shown, the reverse conveying unit 200 includes a reverse conveying input gear 201, a reverse conveying switching gear 202, a reverse conveying output gear 203, a stop retainer 208, and an internal retainer unit 212 including an internal idler gear 204. The reverse conveying input gear 201 is an input component that rotates by receiving driving force transmitted from the aforementioned discharge reverse conveying input gear train 100A. The reverse conveying output gear 203 is an output component that outputs driving force to the three-roller gear 404 that rotates the drive roller 55b of the discharge reverse conveying three-roller 55. The internal idler gear 204 includes two symmetrically arranged gear trains and is a drive transmission component for transmitting the drive from the reverse conveying input gear 201 to the reverse conveying output gear 203. The internal retainer unit 212 and the stop retainer 208 are integrally connected and rotate. Figure 25A and 25B As shown, the reverse transmission input gear 201 includes: an external tooth 201a to which the driving force (i.e., rotation) transmitted from the discharge reverse transmission input gear system 100A is transmitted; and an internal tooth 201b to which the driving force (i.e., rotation) is transmitted to the internal idler gear 204. The external tooth 201a and the internal tooth 201b are gears with the same number of teeth but different modules, and are arranged in the same plane. In this way, the reverse transmission input gear 201 is formed with a vertically and horizontally symmetrical shape. Because the external tooth 201a and the internal tooth 201b are formed symmetrically to each other, resin can be supplied during the molding of the reverse transmission input gear 201. This improves the manufacturing accuracy of the reverse transmission input gear 201.

[0310] The internal retainer unit 212 includes a first internal retainer 212a, a second internal retainer 212b, and an internal idler wheel 204. The internal idler wheel 204 is clamped and rotatably held between the first internal retainer 212a and the second internal retainer 212b. The internal retainer unit 212 rotatably holds the reverse transmission input gear 201 and has a support shaft that rotatably supports the reverse transmission switching gear 202 and the internal idler wheel 204.

[0311] A stop retainer 208 holds a locking lever 209 and a pressing spring 210. The locking lever 209 is rotatably supported relative to the stop retainer 208 about a rotation axis 209c. The locking lever 209 includes a protrusion 209a capable of engaging with a hole 202a formed in the reverse transmission switching gear 202, and a locking portion 209b capable of engaging with the locked portion 201c of the reverse transmission input gear 201. The locking lever 209 is movable to an engaged position where the locking portion 209b engages with the locked portion 201c of the reverse transmission input gear 201, and a non-engaged position where the locking portion 209b does not engage with the locked portion 201c. The reverse transmission switching gear 202, the stop retainer 208, the internal retainer unit 212, the locking lever 209, and the pressing spring 210 constitute a switching unit 360 that outputs the driving force transmitted from the reverse transmission input gear 201 to the reverse transmission output gear 203.

[0312] The pressing spring 210 biases the locking lever 209 toward the engaged position. When the reverse transmission input gear 201 is locked by the locking lever 209 in the engaged position, the reverse transmission input gear 201, the stop retainer 208, and the internal retainer unit 212 become a single unit. In this case, the switching unit 360 is in the first state and outputs driving force to the reverse transmission output gear 203, causing the drive roller 55b of the reverse transmission triple roller 55 to rotate in the second rotation direction RR2 (see...). Figure 28B Rotate.

[0313] The reverse transmission switching gear 202 is configured to control the operation of the locking lever 209 according to its own rotation state. When the locking lever 209 is in the disengaged position and the reverse transmission switching gear 202 is stopped by an external force, the switching unit 360 is in the second state. In the second state, the switching unit 360 outputs driving force to the reverse transmission output gear 203, causing the drive roller 55b discharging the reverse transmission triple roller 55 to rotate in the first rotation direction RR1 (see...). Figure 29B Rotate.

[0314] Furthermore, the reverse transmission unit 200C is configured such that the discharge frame shaft 250 disposed in the discharge frame (not shown) engages with the hole 212c of the internal retainer unit 212 and the hole 203c of the reverse transmission output gear 203 so as to be rotatably supported.

[0315] The meshing relationship between the reverse transmission input gear 201, the reverse transmission output gear 203, and the internal idler gear 204 in the reverse transmission unit 200C is the same as that in the first to third embodiments, so its description will be omitted.

[0316] Internal configuration of planetary gear unit

[0317] Next, we will refer to Figure 26A and 26B Describe the internal configuration of the planetary gear unit 900. For example... Figure 26A and 26B As shown, the planetary gear unit 900 includes a planetary input gear 901, a planetary sun gear 902, a planetary output gear lever 903, and a planetary gear 904.

[0318] The planetary input gear 901, serving as the first rotating element, is an input component that rotates by receiving the driving force transmitted from the aforementioned reverse transmission switching gear 202. The planetary output gear lever 903, serving as the third rotating element, is formed by the contact portion 607c of the lever portion 903a and the intermediate lever 607 (see...). Figure 24A The planetary gear 904 comprises a pair of symmetrically arranged gears and is a drive transmission component for transmitting drive from the planetary input gear 901 to the planetary output gear shaft 903. The planetary input gear 901 has a support shaft that rotatably supports the planetary sun gear 902, the planetary output gear shaft 903, and the planetary gear 904, and is configured to rotatably hold each gear.

[0319] Planetary gear 904 is rotatably arranged on a pair of support shafts provided in planetary input gear 901, inserted into the central shaft 901a of planetary input gear 901, and meshes with planetary sun gear 902, which serves as a second rotating element. Planetary gear 904 meshes with internal gear 903b provided on planetary output gear shaft 903. That is, the driving force of planetary input gear 901 is transmitted to planetary output gear shaft 903 via planetary sun gear 902, a pair of planetary gears 904, and internal gear 903b. The rotation of planetary sun gear 902 can be limited by solenoid unit 800, which serves as a limiting unit.

[0320] Drive switching operation of planetary gear unit

[0321] Next, we will refer to Figures 27A to 27H Describe the drive switching operation of the planetary gear unit 900. Figures 27A to 27D This is a view showing the planetary sun gear 902 not locked to the solenoid rod 802 and in a rotating state. Figures 27E to 27H This is a view showing the planetary sun gear 902 locked to the solenoid rod 802 and in a stopped state. Figure 27A and 27E This is a front view of the planetary gear unit 900, and Figure 27B and 27F This is a rear view of the planetary gear unit 900, with the planetary output gear rod 903 omitted. Figure 27C and 27G This is a front view of the planetary gear unit 900, omitting the planetary input gear 901 and the planetary sun gear 902. Figure 27D and 27H This is a rear view of the planetary gear unit 900.

[0322] like Figures 27A to 27D As shown, when the planetary sun gear 902 is not locked by the solenoid rod 802, the planetary output gear rod 903 is pressed by the intermediate rod 607 biased by the rod return spring 608 and stops in the first rod position. Since the planetary output gear rod 903 is stopped, the driving force transmitted to the planetary input gear 901 is transmitted to the planetary sun gear 902 via the planetary gear 904. When the driving force is transmitted to the planetary sun gear 902 to rotate, the planetary output gear rod 903 can remain stopped in the first rod position. In this case, the guide member 71 is in the first position (…). Figure 9 (The position indicated by the dashed line).

[0323] In other words, when the rotation of the planetary sun gear 902 is not restricted by the solenoid unit 800, the rotation of the planetary input gear 901 is transmitted to the planetary sun gear 902 via the planetary gear 904. Therefore, the drive interruption unit 950 is in a non-transmission state.

[0324] like Figures 27E to 27H As shown, when the locking pawl 902a of the planetary sun gear 902 is locked by the locking pawl 802a of the solenoid rod 802, the planetary sun gear 902 stops. The driving force transmitted to the planetary input gear 901 is transmitted to the planetary output gear rod 903 via the planetary gear 904. The driving force is transmitted to the planetary output gear rod 903, and the planetary output gear rod 903 rotates to rotate the intermediate rod 607. When the intermediate rod 607 rotates, the guide member 71 moves from the first position to the second position. Figure 9 (The position indicated by the solid line).

[0325] In other words, with the rotation of the planetary sun gear 902 restricted by the solenoid unit 800, the rotation of the planetary input gear 901 is transmitted to the planetary output gear rod 903 via the planetary gear 904. Therefore, the drive interruption unit 950 is in the transmission state.

[0326] Operation of the reverse conveyor three rollers and guide components

[0327] Next, we will refer to Figures 28A to 29D Describes the operation of discharging the reverse conveying three rollers 55 and the guide component 71 when the sheet S turns. Figure 28A and 28B These are the front and rear views of the drive mechanism 90E, showing the solenoid 801 in a de-energized state. Figure 28C and 28D These are the front and rear views of the drive mechanism 90E when the solenoid 801 switches from a de-energized state to an energized state. Figure 29A and 29B These are the front and rear views of the drive mechanism 90E, which shows the solenoid 801 in an energized state. Figure 29C and 29D These are the front and rear views of the drive mechanism 90E when the solenoid 801 switches from the energized state to the de-energized state.

[0328] In the following description, for example, a printing operation is performed to drive the drive motor M, and the reverse transmission input gear train 100A and the reverse transmission input gear 201 are rotated by the driving force of the drive motor M.

[0329] like Figure 28A and 28B As shown, when the solenoid 801 is de-energized, the discharge reverse conveying three-roller 55 rotates in the direction shown. Sheet S can be discharged through the discharge clamping part N1 of the discharge reverse conveying three-roller 55 toward the sheet discharge tray 54, and the rotation direction of the discharge reverse conveying three-roller 55 at this time is defined as the reverse direction. When sheet S passes through the reverse conveying clamping part N2 of the discharge reverse conveying three-roller 55 along the first direction D1 (see... Figure 10B The rotation direction of the reverse conveying three rollers 55 during the conveying process is defined as the forward rotation direction.

[0330] When the solenoid 801 is de-energized, the locking pawl 802a of the solenoid rod 802 separates from the locked pawl 902a of the planetary sun gear 902, allowing the planetary sun gear 902 to rotate freely. Meanwhile, the planetary output gear rod 903 is pressed down by the intermediate rod 607, biased by the rod return spring 608, and stops at the first rod position. Therefore, the driving force transmitted from the reverse transmission switching gear 202 to the planetary input gear 901 is transmitted to the planetary sun gear 902, and the planetary sun gear 902 idles.

[0331] Since the planetary output gear lever 903 remains in the first lever position, the intermediate lever 607 and the guide member 71 also stop. That is, the guide member 71 is located in the first position (denoted as Pos1 in the figure) of the discharge clamping part N1 that guides the sheet S to the discharge reverse conveying three rollers 55. When the sheet S is discharged in single-sided printing mode and in double-sided printing mode, the push solenoid 701 is de-energized.

[0332] When sheet S is conveyed to the reverse conveying path R2 in double-sided printing mode, the signal of solenoid 801 switches from OFF to ON, such as Figure 28C and 28D As shown. When the signal of solenoid 801 switches from OFF to ON, solenoid 801 changes from a de-energized state to an energized state. As a result, solenoid arm 801a is driven against the bias force of arm spring 803. Then, the locking pawl 802a of solenoid rod 802, which is interlocked with solenoid arm 801a, locks the locked pawl 902a of planetary sun gear 902, and planetary sun gear 902 stops. As a result, the driving force input to planetary input gear 901 is transmitted to planetary output gear rod 903.

[0333] The planetary output gear lever 903, which receives the driving force, rotates from the first lever position to the second lever position, and the lever portion 903a presses against the contact portion 607c of the intermediate lever 607 to rotate the intermediate lever 607. As the intermediate lever 607 rotates, the guide member 71, which engages with the intermediate lever 607, rotates from the first position to the second position (shown as Pos2 in the figure) to guide the sheet S to the reverse conveying clamping portion N2 of the discharge reverse conveying triple roller 55. After rotating to the second position, the guide member 71 abuts against a frame (not shown) to be held in the second position. As the guide member 71 rotates from the first position to the second position, the rotation of the reverse conveying switching gear 202 is unrestricted and rotates integrally with the reverse conveying input gear 201. That is, the discharge reverse conveying triple roller 55 remains rotating in the reverse direction, the direction in which the sheet S is conveyed to the outside of the device via the discharge clamping portion N1.

[0334] like Figure 29A and 29BAs shown, when the solenoid 801 is energized and the guide member 71 is stopped in the second position, the intermediate rod 607 is in a stopped state with the planetary gear unit 900 and the reverse transmission switching gear 202. When the locking rod 209 rotates together with the reverse transmission input gear 201 in this state, the protrusion 209a of the locking rod 209 moves along the edge of the hole 202a of the reverse transmission switching gear 202 in the stopped state in the direction of arrow M1.

[0335] As a result, the locking lever 209 overcomes the biasing force of the pressing spring 210 and rotates about the rotation axis 209c from the engaged position to the disengaged position (see [link]). Figure 25B Then, as described in the first embodiment, the reverse conveying unit 200 switches from a forward rotation state to a reverse rotation state, and the rotation direction of the reverse conveying output gear 203 is switched. Therefore, the rotation directions of the three-roller gear 404 meshing with the reverse conveying output gear 203 and the discharge reverse conveying three-roller 55 also switch in conjunction with each other. As a result, the discharge reverse conveying three-roller 55 rotates in the forward rotation direction. As a result, the sheet S is guided by the guide member 71 located in the second position to the reverse conveying path R2, and is conveyed in the first direction D1 by the reverse conveying clamping part N2 of the discharge reverse conveying three-roller 55. Figure 10B As shown.

[0336] When the trailing edge of sheet S passes the guide component 71, the signal of solenoid 801 switches from ON to OFF, such as Figure 29C and 29D As shown. When the signal of solenoid 801 switches from ON to OFF, solenoid 801 changes from an energized state to an de-energized state. As a result, solenoid arm 801a returns to its initial position by the bias force of arm spring 803. Then, the locking pawl 802a of solenoid rod 802, which is interlocked with solenoid arm 801a, separates from the locked pawl 902a of planetary sun gear 902, and planetary sun gear 902 can rotate freely. As a result, the driving force input to planetary input gear 901 is transmitted to planetary sun gear 902, and the transmission of driving force to planetary output gear rod 903 is suppressed.

[0337] Therefore, the intermediate rod 607 rotates under the biasing force of the rod return spring 608, and the guide member 71, interlocked with the intermediate rod 607, rotates from the second position to the first position. When the guide member 71 begins to rotate, the reverse transmission switching gear 202 changes from a stopped state to a rotating state, and the locking rod 209 rotates from the engaged position to the engaged position (see...). Figure 25B ).

[0338] Then, as described in the first embodiment, the reverse conveying unit 200 switches from a reverse state to a forward state, and the rotation direction of the reverse conveying output gear 203 is switched. Therefore, the rotation directions of the three-roller gear 404 meshing with the reverse conveying output gear 203 and the discharge reverse conveying three-roller 55 also switch in conjunction with each other. As a result, the discharge reverse conveying three-roller 55 rotates in the reverse direction and passes through the reverse conveying clamping part N2 along the second direction D2 (see...). Figure 10C and 10D Sheet S is then conveyed. Therefore, sheet S is turned and guided by guide member 71 in the first position to double-sided conveying path R3.

[0339] Effects of the sixth embodiment

[0340] As described above, the drive mechanism 90E according to this embodiment uses the driving force of the drive motor M to drive the discharge reverse conveyor roller 55 and the guide member 71. The effect of this embodiment is similar to that of the third embodiment. That is, when switching the rotation direction of the discharge reverse conveyor roller 55 after switching the signal of the solenoid 801, the stopping state of the discharge reverse conveyor roller 55 is shortened as much as possible. Since the time for switching the rotation direction of the discharge reverse conveyor roller 55 is shortened, and the sheet spacing during double-sided printing can be reduced, productivity can be improved.

[0341] Variations of the sixth embodiment

[0342] In this embodiment, a configuration of two planetary gears 904 arranged with planetary gear unit 900 is used, but a configuration of one or more planetary gears 904 may also be used.

[0343] In this embodiment, the planetary sun gear 902 is locked by the locking pawl 802a of the solenoid rod 802. However, it is also possible to use a configuration in which the planetary sun gear 902 can be directly locked by the pawl of the solenoid arm 801a of the solenoid 801.

[0344] In this embodiment, the driving force of the planetary output gear 903 is transmitted to the guide member 71 via the intermediate rod 607. However, a configuration in which the driving force of the planetary output gear 903 can be directly transmitted to the guide member 71 is also possible.

[0345] In this embodiment, a configuration in which the sheet S is conveyed by a three-roller conveyor 55 for discharge and reverse conveying is used, but a configuration in which a sheet discharge roller pair and a reverse conveying roller pair are arranged can also be used.

[0346] In this embodiment, a configuration is used where the driving force transmitted to the guide member 71 is switched via the planetary gear unit 900 and the solenoid unit 800; however, the invention is not limited thereto. For example, such as Figure 30Aand 30B As shown, the configuration for switching the driving force transmitted to the guide member 71 can be achieved using the clutch unit 600. Since the clutch unit 600 has already been described in the first embodiment, its description will be omitted.

[0347] Furthermore, this embodiment uses a configuration where the rotation direction of the discharge reverse conveying three rollers 55 is switched via the reverse conveying unit 200C, but other configurations can also be used. Figure 31A and 31B The arrangement of the reverse transfer unit 200D is shown. Compared to the reverse transfer unit 200C, the reverse transfer unit 200D has a different configuration for supporting the unit. The internal retainer unit 212 rotatably holds the reverse transfer input gear 201 and has support shafts for the reverse transfer switching gear 202, the internal idler gear 204, and the reverse transfer output gear 203. The reverse transfer unit 200C is supported by the discharge frame shaft 250 and the support shafts of the internal retainer unit 212. Meanwhile, the reverse transfer unit 200D is provided with two shafts 212e and 212f extending from the internal retainer unit 212 to both ends, and the reverse transfer unit 200D is supported by these two shafts 212e and 212f.

[0348] Other embodiments

[0349] Although embodiments of the present invention have been described above, the present invention is not limited to the first to sixth embodiments described above. Furthermore, the effects described in the embodiments of the present invention only illustrate the most suitable effects produced by the present invention, and the effects of the present invention are not limited to those described in the embodiments of the present invention.

[0350] In any of the above embodiments, an electrophotographic image forming process has been described as an example of an image forming unit for forming an image on a sheet S. However, the present invention is not limited thereto. For example, as an image forming unit for forming an image on a sheet S, an inkjet image forming process that forms an image by ejecting ink from a nozzle can be used.

[0351] In any of the above embodiments, the printer's discharge reverse conveying section has been described as an example of a sheet conveying device for switching the conveying direction of sheet S. However, the present invention is not limited thereto. For example, the sheet conveying device can be used in other steering mechanisms of an image forming apparatus, or in steering mechanisms such as an ADF (Automatic Document Feeder) capable of automatically feeding documents, or a post-processing device that performs post-processing of the sheet.

[0352] In any of the above embodiments, the configuration of the reverse transfer unit driving the guide member of the guide sheet S and the discharge reverse transfer section for discharging and reversing the sheet S has been described, but the present invention is not limited thereto. For example, the present invention can be applied to the configuration of operating the feeding mechanism (lifting and lowering of the stacking plate, lifting and lowering of the feed roller, rotation of the feed roller, etc.) or the configuration of operating the image forming processing mechanism (e.g., rotation of the photosensitive drum and the developing roller) by the reverse transfer unit.

[0353] In addition, the configurations described in the above embodiments can be combined appropriately.

[0354] Embodiments of the present invention can also be implemented by a computer that reads and executes computer-executable instructions (e.g., one or more programs) recorded on a storage medium (also more fully referred to as a "non-transitory computer-readable storage medium") to perform the functions of one or more embodiments described above and / or includes one or more circuits (e.g., application-specific integrated circuits (ASICs)) for performing the functions of one or more embodiments described above, and by methods performed by the computer of the system or device, such as by reading and executing computer-executable instructions from a storage medium to perform the functions of one or more embodiments described above and / or controlling one or more circuits to perform the functions of one or more embodiments described above. The computer may include one or more processors (e.g., a central processing unit (CPU), a microprocessor unit (MPU)) and may include separate computers or networks of separate processors to read and execute the computer-executable instructions. The computer-executable instructions may be provided to the computer, for example, from a network or storage medium. The storage medium may include, for example, a hard disk, random access memory (RAM), read-only memory (ROM), the memory of a distributed computing system, an optical disk (e.g., a CD), a digital versatile optical disk (DVD), or a Blu-ray disc (BD). TM One or more of the following: flash memory devices, memory cards, etc.

[0355] Other embodiments

[0356] The embodiments of the present invention can also be implemented by providing software (programs) that perform the functions of the above embodiments to a system or device via a network or various storage media, and the computer or central processing unit (CPU) or microprocessor unit (MPU) of the system or device reads out and executes the program.

[0357] Although the invention has been described with reference to exemplary embodiments, it should be understood that the invention is not limited to the disclosed exemplary embodiments. The scope of the appended claims should be given the broadest interpretation to cover all such variations and equivalent structures and functions.

Claims

1. A sheet conveying device, comprising: A conveying section configured to convey sheets, the conveying section including rollers rotatable in a first rotational direction and in a second rotational direction opposite to the first rotational direction; A guide component configured to guide a sheet and move between a first position and a second position different from the first position; Driver source; A drive switching unit includes an input unit, an output unit, and a switching unit. A driving force is input from the drive source to the input unit. The output unit is configured to output the driving force to the roller. In a first state, the switching unit outputs the driving force transmitted from the input unit to the output unit, causing the roller to rotate in a second rotation direction. In a second state different from the first state, the switching unit outputs the driving force transmitted from the input unit to the output unit, causing the roller to rotate in the first rotation direction. as well as A drive interrupt unit is configured to switch between a transmission state in which the driving force transmitted from the switching unit is transmitted to the guiding component, and a non-transmission state in which the driving force is not transmitted to the guiding component. The roller is configured to rotate by a driving force output from the output unit of the drive switching unit while the guide member moves between the first position and the second position. The switching unit transitions from the first state to the second state based on the drive interrupt unit being in the transmission state and the guide component moving from the first position to the second position stopping at the second position.

2. The sheet conveying apparatus according to claim 1, wherein when the drive interruption unit has switched from the non-transfer state to the transfer state, the guide member moves from the first position to the second position by a driving force transmitted from the switching unit via the drive interruption unit.

3. The sheet conveying apparatus according to claim 1, wherein the switching unit remains in the first state when the drive interruption unit is in the conveying state and the guide member moves from the first position to the second position.

4. The sheet conveying apparatus according to claim 1, wherein the switching unit is in the second state when the drive interruption unit is in the conveying state and the guide member stops at the second position.

5. The sheet conveying apparatus according to claim 1, wherein the switching unit switches from the second state to the first state based on the drive interruption unit switching from the conveying state to the non-conveying state and the guide member moving from the second position to the first position.

6. The sheet conveying apparatus according to claim 1, further comprising a biasing unit configured to bias the guide member toward the first position when the drive interruption unit is in the non-transfer state.

7. The sheet conveying device according to claim 1, wherein the drive source is a motor configured to rotate in only one direction.

8. The sheet conveying apparatus according to claim 1, wherein the input unit is rotated by the drive source, and The switching unit rotates in the same direction and at the same speed as the input unit in the first state.

9. The sheet conveying device according to claim 8, wherein the switching unit stops in the second state.

10. The sheet conveying apparatus according to claim 1, wherein the switching unit includes a engagement member capable of engaging with the input unit. When the engaging component is engaged with the input unit, the switching unit rotates integrally with the input unit in the first state, and When the switching unit is in the second state, the engagement component is separated from the input unit.

11. The sheet conveying device according to claim 1, wherein the driving source is a first driving source. The sheet conveying device further includes a second drive source configured to drive the switching unit, and In the first state, the switching unit rotates in the same direction and at the same speed as the input unit under the driving force of the second driving source.

12. The sheet conveying device according to claim 1, wherein the drive interruption unit is a clutch unit that is energized in the conveying state and de-energized in the non-conveying state.

13. The sheet conveying apparatus of claim 1, wherein the drive interruption unit includes a first ratchet portion, a second ratchet portion configured to engage with the first ratchet portion, and a contact separation mechanism configured to engage or disengage the first ratchet portion relative to the second ratchet portion, the drive interruption unit engaging the first ratchet portion and the second ratchet portion with each other via the contact separation mechanism to enter the conveying state, and disengaging the first ratchet portion and the second ratchet portion with each other via the contact separation mechanism to enter the non-conveying state.

14. The sheet conveying apparatus of claim 1, wherein the drive interruption unit comprises a first rotating element configured to mesh with the switching unit and rotatably support a planetary gear, a second rotating element configured to mesh with the planetary gear, a third rotating element configured to mesh with the planetary gear to transmit a driving force to the guide member, and a limiting unit configured to restrict the rotation of the second rotating element. When the rotation of the second rotating element is not restricted by the limiting unit, the drive interruption unit enters the non-transmission state by outputting the rotation of the first rotating element to the second rotating element via the planetary gear. With the rotation of the second rotating element restricted by the limiting unit, the drive interruption unit enters the transmission state by transmitting the rotation of the first rotating element to the third rotating element via the planetary gear.

15. The sheet conveying apparatus according to any one of claims 1 to 14, wherein the conveying section comprises a sheet discharge roller pair and a reverse conveying roller pair including the rollers. The sheet discharge rollers are configured to rotate in a direction that conveys the sheet towards the interior of the sheet conveying device when the rollers rotate in the second rotation direction, and to rotate in a direction that discharges the sheet towards the exterior of the sheet conveying device when the rollers rotate in the first rotation direction. The reverse conveying roller pair is configured to convey the sheet in a first direction toward the interior of the sheet conveying device when the roller rotates in the second rotation direction, and to convey the sheet in a second direction opposite to the first direction when the roller rotates in the first rotation direction.

16. The sheet conveying apparatus according to any one of claims 1 to 14, wherein the conveying section comprises the roller, a first driven roller configured to form a first clamping portion together with the roller, and a second driven roller forming a second clamping portion together with the roller. When the roller rotates along the second rotation direction, the conveying section is configured to convey the sheet toward the interior of the sheet conveying device at the first clamping section, and to convey the sheet in a first direction guiding the sheet toward the exterior of the sheet conveying device at the second clamping section. When the roller rotates in the first rotation direction, the conveying section is configured to discharge the sheet to the outside of the sheet conveying device at the first clamping section, and convey the sheet in a second direction opposite to the first direction at the second clamping section.

17. The sheet conveying apparatus according to any one of claims 1 to 14, wherein the conveying section includes the roller and a third driven roller configured to form a third clamping section together with the roller, and The third clamping part is configured to convey the sheet in a first direction that guides the sheet to the outside of the sheet conveying device when the roller rotates in the second rotation direction, and to convey the sheet in a second direction opposite to the first direction when the roller rotates in the first rotation direction.

18. An image forming apparatus comprising: An image forming unit configured to form an image on a sheet; as well as According to claim 1, the sheet conveying apparatus is configured to convey a sheet on which an image is formed by the image forming unit.

Images