JP4680734B2 - Paper guide device and image forming apparatus equipped with the same - Google Patents

Description

  The present invention relates to a paper guide device such as a cut paper, which can be applied to an image forming apparatus represented by a copying machine or a printer. The present invention also relates to an image forming apparatus equipped with this paper guide device.

  In an image forming apparatus such as a copying machine or a printer, components such as a sheet feeding unit, a transfer unit, a fixing unit, and a sheet reversing unit for duplex printing are arranged, and a sheet conveyance path is formed between them. ing. In such an image forming apparatus, there is an image forming apparatus that employs a switchback method in the sheet reversing unit to switch the sheet conveyance direction. The sheet reversing unit is configured such that the sheet conveying path continuing from the sheet reversing unit branches from the sheet conveying path reaching the sheet reversing unit.

Here, at the place where the two paper conveyance paths branch, it is necessary to prevent the paper from flowing backward when the paper is switched back to the paper conveyance path that has been passed when entering the branching place. For this reason, a movable guide is provided at a location where the two paper conveyance paths branch to assist the conveyance of the paper passing through the two paper conveyance paths. Examples of such a sheet guide device of an image forming apparatus can be seen in Patent Document 1 and Patent Document 2.
JP 2001-316017 A (page 3-5, FIG. 2-3) JP 2002-274747 A (page 4-6, FIG. 2)

  In the paper conveyance device (paper guide device) described in Patent Document 1, a double-sided conveyance path for performing double-sided printing is branched from a discharge conveyance path following the discharge roller from the fixing device. A guide member (movable guide) that is displaced by being pushed and moved by the propelling force of the paper is provided. However, in this paper transport device, the guide member is displaced by pressing the leading edge of the paper from the fixing device toward the discharge roller against the guide member, so that the paper is burdened, wrinkled or torn, Further, there is a possibility that paper jam occurs due to these.

  The double-sided paper feeder (paper guide device) described in Patent Document 2 includes a reversing switching claw (movable guide) that is displaced using a solenoid at a branch portion similar to that of Patent Document 1 described above. However, in this double-sided sheet feeding device, a solenoid is used to displace the reversing switching claw, so that there are problems that the cost is increased, the space for installing the solenoid is secured, and electrical control is required.

  The present invention has been made in view of the above points, and places a load on a sheet at a point where two sheet conveyance paths branch, or attaches an expensive component requiring electrical control such as a solenoid. It is an object of the present invention to provide a paper guide device that can control the posture of a movable guide without causing the paper to smoothly convey paper. It is another object of the present invention to provide a highly reliable image forming apparatus equipped with such a sheet guide device.

  In order to solve the above-described problems, the present invention provides a location where a second sheet conveyance path through which a sheet whose conveyance direction is switched at the sheet discharge port passes from a first sheet conveyance path that reaches a sheet discharge port. Provided with a movable guide whose posture can be changed to assist the conveyance of the sheet passing through the two sheet conveyance paths. The movable guide always conveys the sheet through the first sheet conveyance path. When a discharge roller that is provided near the paper discharge port and switches the paper transport direction sends out the paper toward the second paper transport path, the first posture is supported. In conjunction with the rotation of the discharge roller, the posture is changed to the second posture that assists the conveyance of the sheet passing through the second sheet conveyance path.

  Further, in the paper guide device having the above-described configuration, a clutch mechanism that causes a connection action with the discharge roller when the discharge roller feeds the paper toward the second paper transport path, and a cam that is connected to the clutch mechanism. A cam follower portion that engages with the cam; a slider that slides; a crank lever that is attached to the movable guide and engages with the slider to change the posture of the movable guide to the second posture; And a biasing means for biasing the movable guide to the first posture.

  In the present invention, the paper guide device is mounted on the image forming apparatus.

  According to the configuration of the present invention, the movable guide provided at a position where the second sheet conveyance path through which the sheet whose conveyance direction is switched at the sheet discharge opening passes from the first sheet conveyance path to the sheet discharge opening. However, the discharge roller that always maintains the first posture for assisting the conveyance of the sheet through the first sheet conveyance path and is provided in the vicinity of the sheet discharge port and that switches the sheet conveyance direction is the second one. When the paper is sent out toward the paper transport path, the posture is changed to the second posture that assists the transport of the paper through the second paper transport path in conjunction with the rotation of the discharge roller. The movable guide can be changed to the second posture only when the paper passes through the second paper conveyance path by using the force of rotating the discharge roller. Thereby, the posture of the movable guide can be controlled without imposing a burden on the paper or using an electric component such as a solenoid. Accordingly, it is possible to prevent damage to the paper, increase in cost, and increase in power consumption, and it is possible to prevent the paper from passing through any of the paper transport paths at the point where the two paper transport paths branch. Smooth conveyance is possible.

  In addition, when the discharge roller feeds the sheet toward the second sheet conveyance path, a clutch mechanism that generates a coupling action with the discharge roller, a cam that is coupled to the clutch mechanism, and a cam follower that is engaged with the cam are provided. A slider that is provided and slidably moves, a crank lever that is attached to the movable guide and engages with the slider to change the posture of the movable guide to the second posture; and a bias that biases the movable guide to the first posture When the sheet passes through the second sheet conveyance path, the cam is rotated according to the rotation of the discharge roller by the action of the clutch mechanism, and the cam mechanism including the cam and the cam follower, the slider and the crank The movable guide can be changed to the second posture by the action of the slider crank mechanism including the lever. Further, when the sheet passes through the first sheet conveyance path, that is, when the discharge roller rotates in the direction of conveying the sheet toward the sheet discharge port, the coupling action between the discharge roller and the clutch mechanism does not occur. The movable guide can be automatically changed to the first posture by the urging means. Therefore, with such a simple mechanism, the posture of the movable guide can be freely controlled in response to the sheet passing through one of the two sheet conveyance paths.

  In the present invention, since the sheet guide device is mounted on the image forming apparatus, a load is applied to the sheet at a point where the two sheet conveyance paths are branched, and an expensive and electrical device such as a solenoid is used. Obtaining a highly reliable image forming apparatus capable of controlling the posture of the movable guide without attaching parts that need to be controlled and smoothly transporting the paper to either of the two paper transport paths. be able to.

  Hereinafter, embodiments of the present invention will be described with reference to FIGS.

  First, an image output operation of an image forming apparatus equipped with a paper guide apparatus according to an embodiment of the present invention will be described while explaining the outline of the structure with reference to FIG. FIG. 1 is a schematic vertical sectional front view of an image forming apparatus. Note that solid line arrows in the figure indicate the sheet conveyance path and conveyance direction, and alternate long and short dash line arrows indicate the laser beam L.

  In FIG. 1, a paper feeding unit 3 is disposed at the lower part of the main body 2 of the image forming apparatus 1. Inside the paper feed unit 3, paper P such as cut paper before printing is stacked and stored, and the paper P is separated and sent out one by one.

  A paper transport unit 4 is provided inside the main body 2 and on the left side of the paper feed unit 3. The paper P sent out from the paper supply unit 3 is conveyed vertically upward along the side surface of the main body 2 by the paper conveyance unit 4 and reaches the transfer unit 9.

  On the other hand, a document feeding unit 5 is provided on the upper surface of the image forming apparatus 1, and a document image reading unit 6 is provided below the document feeding unit 5. When a user copies a document, a document on which an image such as a character, a figure, or a pattern is drawn is stacked on the document feeding unit 5. The document feeding unit 5 separates the documents one by one and sends the document, and the document image reading unit 6 reads the image data. The information of the image data is sent to the laser irradiation unit 7 disposed above the paper feed unit 3 and in the center of the main body 2. The laser irradiation unit 7 irradiates the image forming unit 8 with laser light L controlled based on the image data.

  An image forming unit 8 and a transfer unit 9 are provided above the paper transport unit 4 and to the left of the laser irradiation unit 7. In the image forming unit 8, an electrostatic latent image of the document image is formed by the laser light L irradiated by the laser irradiation unit 7. A toner image is developed from the electrostatic latent image, and the toner image is transferred by the transfer unit 9 to the pre-printing paper P sent in synchronization by the paper transport unit 4.

  A fixing unit 10 is provided above the transfer unit 9. The sheet P carrying the unfixed toner image in the transfer unit 9 is sent to the fixing unit 10 where the toner image is heated and pressed by the fixing roller and the pressure roller to be fixed.

  A branch unit 20 is provided above the fixing unit 10. The sheet P discharged from the fixing unit 10 is discharged from the branching unit 20 to the in-body sheet discharge tray 11 provided in the cylinder of the image forming apparatus 1 when duplex printing is not performed.

  The paper discharge port portion from which the paper P is discharged from the branch portion 20 toward the in-body paper discharge tray 11 functions as the switchback portion 30. When performing duplex printing, the switchback unit 30 switches the transport direction of the paper P discharged from the fixing unit 10. Then, the paper P is sent downward through the left side of the fixing unit 10 and the left side of the transfer unit 9, and is sent again to the transfer unit 9 through the paper transport unit 4.

  In such a branching unit 20, the sheet P discharged from the fixing unit 10 is conveyed toward the in-body sheet discharge tray 11, or the sheet P whose conveyance direction is switched by the switchback unit 30 is again transferred to the transfer unit 9. The paper guide device 40 of the present invention is provided at a location where the paper is conveyed toward the direction.

  Next, a detailed configuration around the sheet guide device 40 according to the embodiment of the present invention will be described with reference to FIG. 2 in addition to FIG. FIG. 2 is a partially enlarged schematic vertical sectional view showing the periphery of the sheet guide device. In FIG. 2, the solid line arrows indicate the sheet conveyance path and the conveyance direction.

  As shown in FIG. 2, the sheet guide device 40 is provided in the branching unit 20, and from the discharge sheet conveyance path 12 that is the first sheet conveyance path to the double-sided printing sheet conveyance path that is the second sheet conveyance path. 13 is arranged at a branching point. The discharge paper transport path 12 which is the first paper transport path transports the paper P discharged from the fixing unit 10 (see FIG. 1) to the paper discharge port for the in-body paper discharge tray 11 (see FIG. 1). Road. In the double-sided printing paper conveyance path 13 which is the second paper conveyance path, the paper P whose conveyance direction has been switched by the paper discharge port, that is, the switchback unit 30, reaches the transfer unit 9 again via the paper conveyance unit 4. As is sometimes the case, it is provided at a portion from the branching portion 20 to the left side of the fixing portion 10 and the left side of the transfer portion 9. On the other hand, the paper guide device 40 includes a paper detection means 50 and a movable guide 60.

  The paper detection means 50 is provided with an actuator 51. The actuator 51 is provided at a branching point between the discharge paper conveyance path 12 and the duplex printing paper conveyance path 13 so as to protrude into the conveyance space of the discharge paper conveyance path 12 from the right side in FIG. One actuator 51 is provided at a substantially central portion of the discharge paper transport path 12 in the paper width direction perpendicular to the paper transport direction.

  As shown in FIG. 2, the actuator 51 has an L-shaped front shape when viewed from the paper width direction, and is supported so as to be rotatable about a shaft portion 52 provided at one end thereof. The actuator 51 rotates in a vertical plane around the shaft portion 52 to guide the paper P passing through the double-sided printing paper conveyance path 13 (solid line in FIG. 2) and the discharge paper conveyance path 12. It is possible to change both the posture and the posture for detecting the presence of the paper P (the one-dot chain line in FIG. 2).

  A torsion spring (not shown) as an urging means is provided at a position of the shaft portion 52 of the actuator 51. As a result, the actuator 51 is biased to rotate counterclockwise in FIG. The actuator 51 does not rotate counterclockwise beyond the position shown in FIG. 2 due to the action of a stopper (not shown), and always maintains the posture of guiding the paper P passing through the double-sided printing paper conveyance path 13. is doing. The torsion spring has a resilient force that does not interfere with the clockwise rotation of the actuator 51 due to the contact of the paper P discharged from the fixing unit 10 and passing through the paper transport path 12 for discharge.

  The paper detection means 50 is provided with an optical sensor (not shown) such as a photo interrupter in order to grasp the operation of the actuator 51.

  As shown in FIG. 2, the movable guide 60 is provided between the branch discharge paper conveyance path 12 and the duplex printing paper conveyance path 13. The movable guide 60 has substantially the same length in the paper width direction as the discharge paper transport path 12 and the duplex printing paper transport path 13. The movable guide 60 includes a plurality of guide ribs 61 and a shaft portion 62.

  The plurality of guide ribs 61 are arranged at predetermined intervals along the paper width direction (see FIGS. 4 and 5). The guide rib 61 has a flat plate shape extending in the paper transport direction, and guides the paper P in contact with the paper surface on the transport path at a substantially right angle. As shown in FIG. 2, the guide rib 61 has a wedge shape when viewed from the paper width direction in order to facilitate the sorting of the paper P.

  The shaft portion 62 extends in parallel with the paper width direction and is provided so as to penetrate all the guide ribs 61. The movable guide 60 is rotatably supported at both end portions of the shaft portion 62. The movable guide 60 rotates in a vertical plane around the shaft portion 62 to thereby support the conveyance of the sheet P through the discharge sheet conveyance path 12 which is the first sheet conveyance path (FIG. 2). And a second posture (see FIG. 10) that assists the conveyance of the paper P passing through the double-sided printing paper conveyance path 13 which is the second paper conveyance path.

  As described above, the switchback portion 30 is provided at the paper discharge port portion where the paper P is discharged from the branch portion 20 toward the in-body paper discharge tray 11. The switchback unit 30 includes a discharge roller 31, a roller 32, and a paper discharge port 33.

  The discharge roller 31 and the roller 32 are provided in the vicinity of the paper discharge port 33 through which the paper P comes into contact with each other and is discharged toward the in-body paper discharge tray 11 (see FIG. 1). The discharge roller 31 is provided on the upper side of the paper conveyance path, and the roller 32 is provided on the lower side. The paper P is inserted through a nip formed by contact between the pair of discharge rollers 31 and the rollers 32, and is sent to the in-body paper discharge tray 11 by rotating the discharge rollers 31. When performing duplex printing, the downstream portion of the paper P is discharged from the paper discharge port 33, and when the upstream portion of the paper P reaches the location of the discharge roller 31, the paper P enters the nip between the discharge roller 31 and the roller 32. The conveyance direction of the paper P is switched by reversing the rotation of the discharge roller 31 while holding. The discharge roller 31 is rotated by driving means (not shown), and the roller 32 rotates according to the rotation of the discharge roller 31.

  Here, the movable guide 60 of the sheet guide device 40 is configured to change its posture in conjunction with the rotation of the discharge roller 31. Such a drive mechanism for the movable guide 60 will be described with reference to FIGS. 3 to 7 in addition to FIG. 3 is a front view showing the drive mechanism of the movable guide, FIG. 4 is a right side view, and FIG. 5 is a top view. 6 is a left side view of the clutch mechanism provided in the drive mechanism, and FIG. 7 is a rear view of the clutch mechanism shown in FIG. 6 taken along line VII-VII. 3 to 5, the drawing of the fixed guide member constituting the conveyance space of the paper conveyance path is omitted in part or in whole.

  As shown in FIG. 3, the drive mechanism 70 of the movable guide 60 is provided at a portion between the discharge roller 31 and the movable guide 60. As shown in FIGS. 3 to 5, the drive mechanism 70 includes a drive pulley 71, a driven pulley 72, a belt 73, a clutch mechanism 80, a cam mechanism 100, a slider crank mechanism 110, and a tension spring 74.

  As shown in FIGS. 4 and 5, the discharge roller 31 includes a driven gear 31 b at the end of the shaft portion 31 a. The discharge roller 31 is rotated by driving means (not shown) through the driven gear 31b.

  A drive pulley 71 of the drive mechanism 70 is provided on the shaft portion 31 a of the discharge roller 31. On the other hand, as shown in FIG. 3, a driven pulley 72 is provided in the vicinity of the movable guide 60. A belt 73 is wound around the drive pulley 71 and the driven pulley 72.

  As shown in FIG. 5, a clutch mechanism 80 is provided in the vicinity of the driven pulley 72. As shown in FIG. 6, the clutch mechanism 80 includes a support shaft 81, a shaft portion 82 of a driven pulley 72, a clamping spring 83 that is a clutch element, and an intermittent mechanism 90.

  The shaft portion 82 of the driven pulley 72 is formed integrally with the main body portion of the driven pulley 72. The support shaft 81 passes through the center hole of the driven pulley 72 so that the axis thereof coincides with the axis of the shaft portion 82 of the driven pulley 72. Thereby, the support shaft 81 and the shaft portion 82 of the driven pulley 72 are aligned on the common axis. The support shaft 81 and the driven pulley 72 can rotate independently.

  The tightening spring 83 is configured by a coil spring and is disposed inside the sleeve 91 of the intermittent mechanism 90. The clamping spring 83 is provided so that each axis thereof passes through the inside of the coil so that the axis thereof coincides with the axis of the support shaft 81 and the shaft portion 82 of the driven pulley 72.

  One end of the clamping spring 83 is attached to the flange 84 provided on the support shaft 81, and the other end is attached to the sleeve 91 so as not to rotate. In these attachment portions, the end portion of the coil wire is bent at 90 ° and engaged with the notches provided in the flange 84 and the sleeve 91. The driven pulley 72 is disposed at the end portion of the tightening spring 83 on the side of the engaging portion with the sleeve 91, and the shaft portion 82 of the driven pulley 72 is inserted into the coil from the end portion of the tightening spring 83. The outer diameter of the shaft portion 82 of the driven pulley 72 is a value close to the inner diameter of the coil of the tightening spring 83, and the shaft portion 82 of the driven pulley 72 is connected to the tightening spring 83 when the intermittent mechanism 90 is not operating. Lightly touching. In this way, the clamping spring 83 is interposed between the support shaft 81 and the shaft portion 82 of the driven pulley 72. Therefore, the power from the driving means of the discharge roller 31 is transmitted to the support shaft 81 via the driven pulley 72 and the clamping spring 83.

  As shown in FIGS. 6 and 7, the intermittent mechanism 90 includes a sleeve 91, an engaging claw 92, a locking piece 93, and a stopper 94.

  The sleeve 91 is rotatably provided on the outer side in the radial direction of the support shaft 81 so as to be adjacent to the driven pulley 72. The sleeve 91 is disposed just outside the clamping spring 83 in the radial direction. As described above, one end of the clamping spring 83 is attached to the end portion of the sleeve 91 closer to the driven pulley 72.

  The engaging claw 92 is attached to the outer peripheral surface of the sleeve 91. A plurality of engaging claws 92 are provided along the circumferential direction of the sleeve 91. The engaging claw 92 has a sawtooth cross-sectional shape in a direction perpendicular to the axial direction of the sleeve 91, and one end surface in the circumferential direction of the sleeve 91 is parallel to the radial line of the sleeve 91.

  The locking piece 93 and the stopper 94 are arranged on the outer side in the radial direction of the sleeve 91 and at positions corresponding to the engaging claws 92 of the sleeve 91. The locking piece 93 and the stopper 94 are provided outside the sleeve 91 independently of the sleeve 91 in the radial direction.

  The locking piece 93 is rotatably supported by a support shaft 93 a parallel to the axial direction of the sleeve 91. The locking piece 93 hangs downward, that is, toward the sleeve 91 due to its own weight in the normal state. The lower end of the locking piece 93 is at a height to engage with the engaging claw 92. When the locking piece 93 and the engaging claw 92 are engaged, the end surface of the engaging claw 92 parallel to the radial line of the sleeve 91 faces the locking piece 93.

  As shown in FIG. 7, the stopper 94 is disposed immediately below the support shaft 93a of the locking piece 93 and between the engaging claws 92, and the locking piece 93 exceeds the position shown in FIG. It prevents rotation counterclockwise. Thus, when the sleeve 91 rotates in the clockwise direction in FIG. 7, the rotation is locked by the action of the engaging claw 92, the locking piece 93, and the stopper 94. That is, in FIG. 6, when the paper P passing through the paper discharge path 12 is sent out toward the paper discharge port 33 by the discharge roller 31, the rotation of the sleeve 91 is locked and power is not transmitted to the support shaft 81. On the other hand, when the sleeve 91 rotates counterclockwise in FIG. 7, the sleeve 91 can freely rotate without being locked in rotation. That is, in FIG. 6, when the discharge roller 31 feeds the paper toward the double-sided printing paper conveyance path 13, power is transmitted in order from the driven pulley 72 to the sleeve 91 and the support shaft 81.

  A cam mechanism 100 is provided in the vicinity of the clutch mechanism 80 as described above, as shown in FIGS. The cam mechanism 100 includes a cam 101 and a cam follower 102.

  The cam 101 is fixed to a support shaft 81 of the clutch mechanism 80. As a result, the cam 101 is connected to the clutch mechanism 80 and rotates according to the rotation of the support shaft 81. The cam 101 is an eccentric cam with respect to the support shaft 81. A cam follower portion 102 is disposed below the cam 101 and at a position where it is engaged with the cam 101. The cam follower portion 102 is provided at the upper end portion of the slider 111 of the slider crank mechanism 110 described below.

  As shown in FIGS. 3 and 4, the slider crank mechanism 110 is provided immediately below the cam mechanism 100. The slider crank mechanism 110 is provided with a slider 111 and a crank lever 112.

  As described above, the slider 111 is disposed immediately below the cam 101 of the cam mechanism 100 and includes the cam follower portion 102 of the cam mechanism 100 at an upper end portion thereof. The slider 111 is a member extending in the vertical direction, and the cross-sectional shape viewed from the paper transport direction is L-shaped as shown in FIG. A cam follower portion 102 is provided at a position where the upper end portion is bent horizontally. A pin 111 a that protrudes horizontally is provided below the slider 111. The slider 111 can be slid up and down along a slide guide (not shown).

  One end of the crank lever 112 is fixed to the shaft portion 62 of the movable guide 60. Thereby, the crank lever 112 rotates around the shaft portion 62 of the movable guide 60 according to the rotation of the movable guide 60. A slit 112a extending in the longitudinal direction of the lever is provided at a substantially central portion of the crank lever 112. The pin 111a of the slider 111 is inserted into and engaged with the slit 112a. As a result, as the slider 111 moves up and down, the crank lever 112 and the movable guide 60 change the angle around the shaft portion 62.

  A spring mounting hole 112b is provided at the end of the crank lever 112 opposite to the end of the movable guide 60 on the shaft 62 side. Here, the lower end of the tension spring 74 is attached. The upper end of the tension spring 74 is attached to the main body 2, and a biasing force is applied to the tension spring 74 to lift the crank lever 112 upward. Thereby, the movable guide 60 is rotated clockwise in FIG. 3, and the tension spring 74 acts as a biasing means that biases the movable guide 60 to the first posture.

  Subsequently, the guidance operation of the paper P by the paper guidance device 40 will be described with reference to FIGS. 8 to 10 in addition to FIGS. 2, 3, 6, and 7.

  FIG. 8 is a model vertical cross-section left side view showing the same clutch mechanism as in FIG. 6 and shows a state where the connection between the driven roller and its support shaft is released. 9 is a front view showing the driving mechanism of the movable guide similar to FIG. 3, showing the state where the movable guide is in the second posture, and FIG. 10 is a model showing the periphery of the sheet guiding device similar to FIG. It shows a state where the movable guide is in the second posture in a partially enlarged view of the vertical cross section. In FIG. 10, solid arrows indicate the sheet conveyance path and conveyance direction.

  When the paper P discharged from the fixing unit 10 is sent out toward the paper discharge port 33 through the discharge paper transfer path 12 which is the first paper transfer path, the discharge roller 31 rotates counterclockwise in FIG. . As a result, the belt 73 of the drive mechanism 70 shown in FIG. 3 also rotates counterclockwise via the drive pulley 71. Further, the driven pulley 72 is also rotated counterclockwise by the belt 73.

  At this time, in the clutch mechanism 80 shown in FIG. 6, the clamping spring 83 is wound around the shaft portion 82 of the driven pulley 72 until the engagement claw 92 of the intermittent mechanism 90 and the locking piece 93 are engaged. 91 rotates following the driven pulley 72.

  When the engaging claw 92 and the locking piece 93 are engaged and locked by the stopper 94, the sleeve 91 is braked and the rotation of the sleeve 91 is stopped. At the same time, the rotation of the clamping spring 83 with one end engaged with the sleeve 91 and the support shaft 81 engaged with the other end of the clamping spring 83 is also stopped. At this time, since the driven pulley 72 remains rotated, the tightening spring 83 is twisted in the expansion direction due to friction between the shaft portion 82 of the driven pulley 72 and the tightening spring 83. As a result, the tightening of the tightening spring 83 at the shaft portion 82 of the driven pulley 72 is loosened, and the shaft portion 82 of the driven pulley 72 slides inside the coil of the tightening spring 83, and as shown in FIG. The connection with the spring 83 is released. Therefore, even if the driven pulley 72 is rotated to send the paper P toward the paper discharge port 33 through the discharge paper transport path 12 (arrow A in FIG. 8), this power is transmitted to the support shaft 81. There is no.

  In this way, since no power is transmitted to the support shaft 81 shown in FIG. 3, the cam 101 of the cam mechanism 100 has no force to push down the slider 111 of the slider crank mechanism 110. Accordingly, the crank lever 112 is not displaced, and the movable guide 60 is rotated clockwise in FIG. 3 by the tension spring 74, that is, the sheet P passing through the discharge sheet conveyance path 12 which is the first sheet conveyance path. A first posture for assisting conveyance is maintained.

  On the other hand, when the transport direction is switched by the switchback unit 30 and the paper P is sent out toward the double-sided printing paper transport path 13 which is the second paper transport path, the discharge roller 31 rotates clockwise in FIG. . As a result, the drive pulley 71, the belt 73, and the driven pulley 72 are rotated in the clockwise direction.

  At this time, in the clutch mechanism 80 shown in FIG. 7, the sleeve 91 also rotates counterclockwise in accordance with the rotation of the driven pulley 72, so that the engaging claw 92 of the intermittent mechanism 90 and the locking piece 93 are not engaged. . In the state where the sleeve 91 rotates in this direction, the clamping spring 83 is wound around the shaft portion 82 of the driven pulley 72 as shown in FIG. Thereby, the sleeve 91 and the driven pulley 72 are connected via the clamping spring 83. Therefore, when the driven pulley 72 is rotated to feed the paper P toward the double-sided printing paper conveyance path 13, the power is transmitted to the support shaft 81. That is, when the clutch mechanism 80 feeds the paper P toward the double-sided printing paper transport path 13, a coupling action with the discharge roller 31 occurs.

  In this way, the support shaft 81 shown in FIG. 9 rotates clockwise as the driven pulley 72 rotates. The cam 101 fixed to the support shaft 81 also rotates, and the slider 111 is pushed down. Note that the cam 101 does not rotate in the clockwise direction beyond the position of FIG. 9 where the slider 111 is slid down most by the action of a stopper (not shown). In addition, a torque limiter (not shown) is provided between the support shaft 81 and the cam 101. When the cam 101 is displaced to the position shown in FIG. A torque greater than the torque is applied, and the support shaft 81 continues to rotate as it is.

  When the slider 111 is pushed down by the cam 101, the crank lever 112 is rotated counterclockwise in FIG. 9 against the elastic force of the tension spring 74. Accordingly, the movable guide 60 is also rotated, and the second posture for assisting the conveyance of the paper P passing through the double-sided printing paper conveyance path 13 which is the second paper conveyance path shown in FIG. 9 is maintained. Therefore, as shown in FIG. 10, in the paper guide device 40, a path for sending the paper P from the discharge roller 31 toward the double-sided printing paper conveyance path 13 is secured as the discharge roller 31 rotates.

  As described above, it is the second paper transport path through which the paper P whose transport direction is switched at the paper discharge port 33 passes from the discharge paper transport path 12 which is the first paper transport path to the paper discharge port 33. A movable guide 60 provided at a location where the duplex printing paper conveyance path 13 branches always maintains a first posture for assisting conveyance of the paper P passing through the discharge paper conveyance path 12. When the discharge roller 31 that is provided near the discharge port 33 and switches the conveyance direction of the paper P sends out the paper P toward the double-sided printing paper conveyance path 13, the double-sided printing is performed in conjunction with the rotation of the discharge roller 31. Since the posture is changed to the second posture that assists the conveyance of the paper P passing through the paper conveyance path 13, only when the paper P passes through the double-sided printing paper conveyance path 13 by using the rotating force of the discharge roller 31. , Movable guide 0 can be attitude changed to the second posture. Thereby, the posture of the movable guide 60 can be controlled without imposing a burden on the paper P or using an electric component such as a solenoid. Therefore, it is possible to prevent damage to the paper P, increase in cost, and increase in power consumption, and it is possible to prevent the paper from passing through any of the paper transport paths at the point where the two paper transport paths branch. P can be transported smoothly.

  Further, when the discharge roller 31 feeds the paper P toward the double-sided printing paper conveyance path 13, a clutch mechanism 90 that generates a connection with the discharge roller 31, a cam 101 connected to the clutch mechanism 90, and the cam A cam follower portion 102 that engages with the slider 101, a slider 111 that slides, and a crank lever 112 that is attached to the movable guide 60 and engages with the slider 111 to change the posture of the movable guide 60 to the second posture. In addition, since the tension spring 74 is provided as a biasing means for biasing the movable guide 60 to the first posture, the cam 101 is moved by the action of the clutch mechanism 90 when the paper P passes through the paper transport path 13 for double-sided printing. The cam mechanism 100 including the cam 101 and the cam follower 102, the slider 111, and the clutch rotate according to the rotation of the discharge roller 31. By the action of a slider crank mechanism 110 consisting Nkureba 112, it is possible to change the posture of the movable guide 60 to the second position. Further, when the paper P passes through the discharge paper transport path 12, that is, when the discharge roller 31 rotates in the direction of transporting the paper P toward the paper discharge port 33, the connection between the discharge roller 31 and the clutch mechanism 90 is performed. Since no action occurs, the movable guide 60 can be automatically changed to the first posture by the tension spring 74. Therefore, with such a simple mechanism, the posture of the movable guide 60 can be freely controlled in response to the sheet P passing through one of the two sheet conveyance paths.

  In the present invention, since the sheet guide device 40 is mounted on the image forming apparatus 1, a load is applied to the sheet P at a point where the two sheet conveyance paths are branched, and an expensive and electrical device such as a solenoid is used. A highly reliable image forming apparatus capable of controlling the posture of the movable guide 60 without attaching parts that need to be controlled and smoothly transporting the paper P to either of the two paper transport paths. 1 can be obtained.

  Although the embodiments of the present invention have been described above, the scope of the present invention is not limited to these embodiments, and various modifications can be made without departing from the spirit of the invention.

  The present invention can be used in a sheet guide device in which a movable guide is provided at a position where two sheet conveyance paths branch.

1 is a schematic vertical sectional front view of an image forming apparatus equipped with a paper guide device according to an embodiment of the present invention. FIG. 2 is a partially enlarged view of a schematic vertical section showing the periphery of the sheet guide device in FIG. 1. It is a front view of the drive mechanism of the movable guide shown in FIG. It is a right view of the drive mechanism of the movable guide shown in FIG. It is a top view of the drive mechanism of the movable guide shown in FIG. FIG. 6 is a left side view of a vertical cross section of a clutch mechanism provided in the drive mechanism of FIG. 5. It is a vertical cross-section rear view in the VII-VII line of the clutch mechanism shown in FIG. FIG. 7 is a left side view of a model vertical section showing the same clutch mechanism as in FIG. 6, showing a state where the connection between the driven roller and its support shaft is released. FIG. 5 is a front view showing a driving mechanism for a movable guide similar to that in FIG. 3 and shows a state in which the movable guide is in a second posture. FIG. 3 is a schematic vertical sectional partial enlarged view showing the periphery of the sheet guide device similar to FIG. 2, showing a state where the movable guide is in the second posture.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Image forming apparatus 12 Discharge paper conveyance path (1st paper conveyance path)
13 Double-sided printing paper transport path (second paper transport path)
DESCRIPTION OF SYMBOLS 30 Switchback part 31 Discharge roller 31a Shaft part 33 Paper discharge port 40 Paper guide apparatus 60 Movable guide 61 Guide rib 62 Shaft part 70 Drive mechanism 71 Drive pulley 72 Driven pulley 72a Shaft part 73 Belt 74 Tension spring (biasing means)
80 Clutch mechanism 81 Support shaft 82 Shaft (driven pulley)
83 Clamping spring (clutch element)
90 Intermittent mechanism 91 Sleeve 100 Cam mechanism 101 Cam 102 Cam follower section 110 Slider crank mechanism 111 Slider 112 Crank lever

Claims (2)

A second sheet conveyance path through which a sheet whose conveyance direction is switched at the sheet discharge opening passes from the first sheet conveyance path to the sheet discharge opening is provided at a branching point. With a movable guide that can change posture to assist in transporting paper
The movable guide always maintains a first posture for assisting the conveyance of the sheet passing through the first sheet conveyance path, and is provided in the vicinity of the sheet discharge port so as to change the sheet conveyance direction. When the roller feeds the sheet toward the second sheet conveyance path, the posture is changed to the second posture that assists the conveyance of the sheet through the second sheet conveyance path in conjunction with the rotation of the discharge roller. A paper guide device,
A clutch mechanism that generates a coupling action with the discharge roller when the discharge roller sends out the sheet toward the second sheet conveyance path;
A cam connected to the clutch mechanism;
A cam follower portion that engages with the cam, and a slider that slides;
A crank lever attached to the movable guide and engaged with the slider to change the posture of the movable guide to the second posture;
Biasing means for biasing the movable guide to the first posture;
A stopper for preventing the cam from rotating so that the movable guide maintains the second posture;
A paper guide device further comprising: An image forming apparatus comprising the paper guide device according to claim 1.

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