STACKING APPARATUS
There is provided a stacking apparatus capable of stably conveying and stacking sheets without occurrence of damage or buckling of the sheets in the structure of discharging the curled sheets one by one. In regard to each of a plurality of clamp guides which project toward stacking trays from conveyance means to guide sheets S, the projecting position varies in accordance with a size and an amount of stacked sheets Sa on the stack trays. The stacking tray comprises an inclined surface and a curved surface. An upper guide is located to face the inclined surface by a predetermined interval, and the upper guide is located not to face the curved surface or is located to face it by an interval larger than a predetermined interval.
1. Field of the Invention
The present invention relates to a stacking apparatus for stacking discharged sheets.
2. Description of the Related Art
In an apparatus for discharging a large-sized sheet as an output, such as a large-sized inkjet printer, the outputs may be accommodated in a container such as a basket. However, continuously discharging a plurality of the sheets into such a basket may cause the outputs to collide with each other every time a new sheet is discharged, possibly resulting in occurrence of damage, buckling and/or the like. Further, in the structure of printing an image on a continuous sheet held in a roll form before cutting the continuous sheet in accordance with the image, the cut sheet remains curled, making it difficult to stack and keep hold of a large number of sheets in the basket. Then, in recent years, a stacking apparatus (stacker) is provided to orderly stack sheets discharged from an apparatus for handling large-sized sheets.
Most of stacking apparatuses are structured such that a stacking tray for holding the discharged sheets is placed in a position downward in the gravity direction from the discharge port of a discharging apparatus and the discharged sheets respectively drop in order due to each own weight of the sheets to be stacked thereon. However, in a case of conveying and stacking strongly curled sheets, the leading end of the sheet during the discharge possibly abuts at a large angle on a stacking surface of the stacking tray to cause a conveyance failure of the sheet.
For solving this problem, Japanese Patent Laid-Open No. 2003-182915 discloses a supplementary tray which can be taken in and out for guiding and supporting sheets from the discharge port to the stacking tray. According to Japanese Patent Laid-Open No. 2003-182915, at the time when the leading end of the sheet passes through, the supplementary tray projects to cover a level difference gap between the discharge port and the stacking surface, and guides the sheet from the discharge port to the stacking surface while supporting it. On the other hand, at the time when the rear end of the sheet passes through, the supplementary tray retracts to expose the level difference gap between the discharge port and the stacking tray and cause the sheet rear end to drop to a predetermined position of the stacking surface.
In a case where the sheet already stacked on the stacking tray remains curled in a convex shape due to the curl, when the leading end of the incoming sheet newly discharged comes in contact with the mid-slope of convex the curl and moves forward, the sheet already stacked on the stacking tray is possibly pushed out of the stacking tray. To address this, for example, Japanese Patent Laid-Open No. 2003-261255 discloses the structure in which a concave configuration is provided on the stacking tray in a position in which the rear end of the sheet should be aligned and the rear end of the sheet curled in the convex shape is caused to enter into the concave configuration. When the rear end of the sheet enters into the concave configuration, even if the mid-slope of the sheet is pushed in the conveyance direction by the incoming sheet newly discharged, the travel of the sheet can be restricted, resulting in the aligning stacking of the sheets.
However, according to the structure disclosed in Japanese Patent Laid-Open No. 2003-182915, the supplementary tray does not project enough to contact with the stacking tray or the already stacked top sheet. Therefore the level difference gap still exists to some extent between the supplementary tray and the stacking tray. Further, even if the posture of the supplementary tray is designed to be adjusted in accordance with the amount of the stacked sheets such that this level difference gap is made sufficiently small, when a sheet of a large width is discharged in a state where a sheet of a small width is stacked thereon, a large level difference gap exists in a region where the sheet of the small width is not stacked. As a result, when the largely curled sheet is conveyed, the leading end enters into the level difference gap, possibly making normal conveyance impossible.
As in the case of Japanese Patent Laid-Open No. 2003-261255, in the structure provided with the concave portion for restricting the rear ends of the already stacked sheets, when the sheet number of the stacked sheets becomes large (for example, 100 sheets or more), the rear end of the top sheet cannot be sufficiently subjected to the restriction by the concave portion. Therefore when the leading end of the incoming sheet newly discharged comes in contact with the mid-slope of the stacked curled sheet and moves forward, the stacked sheet is moved to destroy the stacking state.
SUMMARY OF THE INVENTIONThe present invention has been made to address such problems. Therefore, it is an object of the present invention to provide a stacking apparatus capable of stably conveying and stacking sheets without occurrence of damage or buckling of the sheets in the structure of discharging the curled sheets one by one.
According to a first aspect of the present invention, there is provided a sheet stacking apparatus, comprising:
a tray on which a sheet is placed in an inclined condition; and a guide unit that guides a sheet conveyed on the tray and restrains an end of the sheet placed on the tray, wherein the guide unit comprises a plurality of movable guides which are divided in a width direction of the sheet and are movable in accordance with the sheet placed on the tray.
According to a second aspect of the present invention, there is provided a sheet stacking apparatus in which a sheet is supported in an inclined condition by a tray, and a part of the sheet is stacked in a hanging-downward condition from the tray, wherein the tray includes an inclined surface and a curved surface, wherein the sheet conveyed to the tray goes up in the upward direction against gravity along the inclined surface and hangs downward via the curved surface, an upper guide facing the inclined surface to have a predetermined interval therefrom is provided, wherein the upper guide is not faced the curved surface or faced a part of the curved surface in having an interval larger than the predetermined interval.
Further features of the present invention will become apparent from the following description of exemplary embodiments (with reference to the attached drawings).
The stacker (stacking apparatus) according to the present invention is not limited to being used in a combination with the inkjet printer, may be used in a combination with another printing-type printer. Further, the stacker can be used for stacking sheets discharged from an image reader and other sheet processing devices as well as the printers.
The structure of the conveyance path will be now described in detail. The sheet S supplied from the roll sheet 1 is conveyed onto a platen 6 while being held between a printer conveyance roller 3 and a printer pinch roller 4. The platen 6 is located opposite to a print head 5 that ejects ink in response to image data, to support the sheet S from below during a printing operation. The platen 6 has a suction port formed to communicate with a duct and/or a suction fan (which are not illustrated) for suction from behind the sheet S during conveyance, maintaining flatness of the sheet S. After an image corresponding to one page has been printed with the progress of the printing operation of the inkjet-type print head 5, a cutter 8 cuts the sheet S in line with the rear end of the image.
After discharge of the leading end of the cut sheet S from the discharge guide 9 of the printer 100, the cut sheet S is delivered into the stacker 101 through a conveyance unit 102. A conveyance roller 12 placed in the conveyance unit 102 is driven at the time when a sheet detection sensor 22 installed in the stacker 101 detects the leading end of the cut sheet S discharged from the discharge guide 9, so that the cut sheet S is held between the conveyance roller 12 and a pinch roller 13 to be conveyed to the tray unit 103. When the cut sheet S is of a sufficient size, the sheet S is held in such a manner that the leading end hangs and extends downward beyond the end of a stacking tray 16.
The printer 100 is equipped with an operating part for a user to input a width size of the roll sheet 1 loaded, select between online and offline, input commands, and the like.
A lower conveyance guide 20 and an upper conveyance guide 21 are provided to guide the sheet S having reached between joint part 10 and the upper guide 11, further to a nipping portion between the conveyance roller 12 and the pinch roller 13. The pinch roller 13 is rotatably mounted in the upper conveyance guide 21 in such a manner as to be urged toward the conveyance roller 12 by unillustrated urging means. Further, a discharge roller holder 29 is rotatably attached to the upper conveyance guide 21 to support a discharge roller 15. On the other hand, in the middle of the lower conveyance guide 20, the sheet detection sensor 22 is provided for detection of the leading end and/or the rear end of the sheet S.
The sheet S, which has passed through the nipping portion between the conveyance roller 12 and the pinch roller 13, is moved forward through between an upper guide 17 and the stacking tray 16 of the tray unit 103, and finally held as stacked sheets Sa on the stacking tray 16. The upper guide 17 and the stacking tray 16 are inclined with respect to the horizontal direction (Y direction). The upstream end of the stacking tray 16 is located in a position lower by a distance H than the nipping portion between the conveyance roller 12 and the pinch roller 13 in the gravity direction (Z direction). An adjoining portion 16d, which is formed at the upstream end of the stacking tray 16, abuts on the conveyance roller 12 in a comb-teeth manner, thus preventing the stacked sheets Sa from slipping down from the stacking tray 16.
A clamp guide 14 (movable guide) is provided to enable connection and disconnection between the nipping portion and the stacking tray 16. The clamp guide 14 is formed of a flat plate somewhat warping in response to a pressure from outside, and is capable of being moved forward and backward in the Y direction in the figure by moving means which will be described later. The clamp guide 14 plays a role as a guide of smoothly guiding sheets carried into the stacking tray 16 and a role as a clamper of pressing the distal ends of the sheets placed on the stacking tray 16. In the present specification, the state where the clamp guide 14 has moved to the most rearward position is herein referred to as a retract state, and the state where the clamp guide 14 has moved forward in the Y direction is herein referred to as a projecting state.
A roller 24 that is a rolling element is attached to the leading end of the clamp guide 14. While maintaining contact with the stacking tray 16 or the stacked sheets Sa, the roller 24 is rotated to move forward in the Y direction. In the projecting state illustrated in
In the projecting state, the discharge roller 15 is in contact with the upper surface of the clamp guide 14, so that the discharge roller 15, together with the discharge roller holder 29, is lifted by the reaction of the clamp guide 14. Upon discharge of a new sheet S in this state, the new sheet S is conveyed in the Y direction with the rotation of the discharge roller 15, while being guided by the clamp guide 14. Then, the new sheet S is stacked as a top sheet of the sheets stacked on the stacking tray 16. At this time, even if the newly discharged sheet S somewhat curls as shown in
The conveyance rollers 12 are connected with each other to be rotatable by a conveyance-roller motor 23 through a common torque-limiter gear 31. The conveyance-roller motor 23 is driven at the time when the sheet detection sensor 22 detects the leading end of the sheet S to start rotating the conveyance rollers 12. When the sheet S is conveyed by both the printer conveyance roller 3 and the conveyance rollers 12 in the stacker 101, the conveyance rates of the conveyance rollers 3 and 12 are controlled to become equal. For example, when the conveyance operation of the printer conveyance roller 3 is stopped in the middle of the conveying process, the torque-limiter gear 31 with a limit value being reached starts sliding on the sheet S to stop the rotation of the conveyance rollers 12. On the other hand, when the sheet S is cut and the sheet S in the stacker 101-side is conveyed by the conveyance rollers 12 alone in the stacker 101, the conveyance rate of the conveyance rollers 12 is able to be independently controlled in the stacker 101-side.
The clamp guides 14 are held respectively in holders 25. A plurality of the holders 25 are connected to a clamp-guide motor 28 through a common clamp-guide shaft 30. By the drive force of the clamp-guide motor 28, gears 26 rotate in a forward or backward direction to move each clamp guide 14 forward or backward in the Y direction through guide rails 32 meshing with the gears 26. A torque limiter 27 is attached to the gears 26 of each holder 25. The extent of the forward movement or backward movement caused by the clamp-guide motor 28 is adjusted for each clamp guide 14 by the torque limiter 27.
Specifically, when the clamp-guide motor 28 rotates to move the clamp guides 14 forward, the rollers 24 of the respective clamp guides 14 come into contact with the stacking trays 16 or the stacked sheets Sa, and the torque limiters 27 are activated at the time of receiving reaction to some extent, the clamp guides 14 coming to a stop. That is, in a plurality of the clamp guides 14 arranged in the X direction, the extent of the forward movement is adjusted in accordance with the thickness of the stacked sheets in each position of the clamp guides 14.
On the other hand, for the clamp guides 14 located in the region B in which the stacked sheets Sa do not exist, the torque limiters 27 are activated to stop travel of the clamp guides 14 with the rollers 24 directly abutting on the stacking trays 16 as illustrated in
After it is determined at step S100 that the power is turned on, the controller 200 goes to step S101, wherein it is determined whether or not the sheet detection sensor 22 detects the leading end of the sheet S. When the leading end of the sheet S is not detected, step S101 is periodically repeated until the leading end of the sheet S is detected.
After the leading end of the sheet S is detected at step S101, the controller 200 goes to step S102, wherein the conveyance rollers 12 and the clamp guide motor 28 are driven.
At step S103 the controller 200 determines whether or not the sheet detection sensor 22 detects the rear end of the sheet S. When the rear end of the sheet S is not detected, the controller 200 goes back to step S102, wherein the conveyance-roller motor 23 and the clamp-guide motor 28 continue to be driven. When the rear end of the sheet S is detected at step S103, the controller 200 goes to step S104.
At step S104 the controller 200 determines whether or not a first predetermined time has elapsed from the time of detection of the rear end of the sheet S. When it is determined that the first predetermined time has not elapsed, the conveyance-roller motor 23 and the clamp-guide motor 28 continue to be driven. When it is determined at step S104 that the first predetermined time has elapsed, the controller 200 goes to step S105, wherein while maintaining the driving of the conveyance-roller motor 23, the clamp-guide motor 28 is rotated in the reverse direction to start retracting the clamp guides 14 in the negative Y direction.
At the time when the rear end of the sheet S is discharged from the nipping portion between the conveyance rollers 12 and the pinch rollers 13, the clamp guides 14 have returned to the retract state completely. Hence, the discharge rollers 15 are in contact with the rotating conveyance rollers 12 to form a nipping portion, so that the rear end of the discharged sheet S is prevented from coming into contact with the retracting clamp guides 14 to be pulled back in the negative Y direction or from coming into contact with the conveyance rollers 12 to suffer occurrence of damage or buckling. Further, the level difference gap H between the stacking trays 16 and the nipping portion between the discharge rollers 15 and the conveyance rollers 12 is completely exposed, so that the rear end of the sheet S is dropped onto a prescribed position of the stacking trays 16. In this way, the first predetermined time is set such that the clamp guides 14 are placed in the projecting state as much as possible during the conveyance of the sheet S, but is returned completely to the retract state at the time when the rear end of the sheet S is discharged from the nipping area.
Then, at step S106, the controller 200 determines whether or not a second predetermined time has elapsed from the time of detection of the rear end of the sheet S, and continues to drive the conveyance motor 23 until it is determined that the second predetermined time has elapsed. In this connection, the second predetermined time is a value larger than the first predetermined time, and is a sufficient length of time for the rear end of the sheet S to be dropped onto the stacking trays 16 after having passed through the sheet detection sensor 22.
Hereinafter, a method of setting the first predetermined time will be described. As described earlier, the first predetermined time is set for the time the clamp guides 14 start to move backward in order to return to the retract state at the time when the rear end of the sheet S is discharged from the nipping portion after the clamp guides 14 have been maintained in the projecting state as much as possible. The projecting state is maintained as much as possible during the conveyance of the sheet S in order to minimize the time and the distance during which the stacked sheets Sa are subjected to the friction of a newly discharged sheet S for the prevention of multi-feeding.
However, the possibility of occurrence of such multi-feeding varies depending on a use environment of the stacker 101 and/or a sheet type of the sheet S. Even if multi-feeding occurs somewhat, depending upon the use environment or the sheet type, the rear ends of the stacked sheets Sa may be aligned because of the inclination of the stacking tray 16 at the time when the sheet discharge is completed, so that the stacking performance may not be affected. That is, when multi-feeding easily occurs, the timing of starting the backward movement of the clamp guides 14 is recommended to be set as late as possible. On the other hand, when the multi-feeding is not much of a problem, the backward movement of the clam guides 14 is preferably started earlier with time to spare, with consideration given to a conveyance speed error and the like. Accordingly, in the present embodiment, the first predetermined time is changed depending on the use environment of the stacker and the type of sheet.
Such a standby time, that is, the first predetermined time can be calculated from the retracting speed and the retracting distance of the clamp guides 14 in use. In the case where Vc is the retracting speed of the clamp guides 14, and Lmax is the retracting distance when there are no stacked sheets Sa on the stacking trays 16, that is, when the clamp guides 14 project at the maximum, a time Tc required for the retract is given by:
Tc=Lmax/Vc
Also, in the case where Ls is the distance from the sheet detection sensor 22 to the nipping portion of the conveyance rollers 12, Vs is the speed with which the conveyance rollers 12 convey the sheet, and Tw is the first predetermined time, a time Is from when the clamp guides 14 start moving backward to when the sheet S comes off the nipping portion is expressed by:
Ts=Ls/Vs−Tw
Then, in order for the retract movement of the clamp guides 14 to be completed before the sheet S is away from the nipping portion, the following is necessary:
Tc<Ts, that is,
Lmax/Vc<Ls/Vs−Tw Express 1
In this respect, it is assumed that the speed Vs with which the conveyance rollers 12 convey the sheet varies depending on the use environments and/or the type of sheet. Considering such errors of the conveyance speed Vs, a Tw appropriate in accordance with each condition is determined in advance such that the expression 1 is satisfied under any condition.
For maintaining the projecting state during the conveyance of the sheet S as long as possible, an increase of the retracting speed of the clamp guides 14 is effective. Accordingly, the travel speed Vc of the clamp guides 14 will be adjusted to the extent that no problem arises on the endurance of the mechanism involved in the travel of the clamp guides 14, such as the clamp-guide motor 28, the torque limiters 27 and the like. Thus, for example, even if the friction is large to cause multi-feeding to occur easily, increasing the travel speed Vc of the clamp guides 14 makes it possible to maintain the projecting state for a longer time.
In another method, decreasing the conveyance speed of the sheet S is effective. The conveyance speed of the sheet S in the stacker 101 is required to be synchronized with the printer conveyance roller 3 until the sheet S during conveyance is cut by the cutter 8 of the printer 100, but after the cutting process, the stacker-specific conveyance control can be exercised. Accordingly, the conveyance speed Vs will be adjusted to the extent that no problem arises on the endurance of the mechanisms relating to the conveyance rollers 12, such as the conveyance motor 23, the torque limiter gear 31 and the like. By performing such control, for example, even in the case where the friction is large to cause multi-feeding to occur easily, decreasing the conveyance speed Vs of the sheet S makes it possible to set the first predetermined time Tw to an adequate large value. Further, when both the travel speed Vc of the clamp guides 14 and the conveyance speed Vs of the sheet S are adjusted, the first predetermined time Tw is able to be set to a larger value to further delay the time when the clamp guides 14 retract from the stacked sheets Sa. In this way, starting the backward movement of the clamp guides 14 at the time appropriate in accordance with the use environment of the stacker and the type of sheet enables the discharge and stacking of sheets to be stably executed under various conditions.
Next, the outline of the tray unit 103 will be described.
In addition, the tray unit 103 is designed such that, as long as the sheet S is of an A-series or B-series standard size, when one end of one side of the sheet S is aligned with a reference end in
A plurality of the stacking trays 16 are connected to each other on the upstream side in the conveyance direction by a rod-shaped tray upstream frame 42 extending in the X direction, and on the downstream side by a curved-surface shaped tray downstream frame 43 extending in the X and Y directions. On the other hand, a plurality of the upper guides 17 are connected to each other on the surrounding by an upper-guide frame 41, and on the upstream side in the conveyance direction by an upper-guide rotating shaft 40. Further, stoppers 44 are attached to both sides around the downstream end of the upper-guide frame 41 to abut on both sides of a set of the opposite stacking trays 16 to maintain a constant distance from the stacking trays 16. The user can use the stoppers 44 as handles to rotate a plurality of the upper guides 17 fixed to the upper-guide frame 41 about the upper-guide rotating shaft 40 for removal of the stacked sheets Sa stacked on the stacking tray 16.
Referring to
A plurality of the inclined surfaces 16a arranged in the X direction have the respective upstream ends connected to each other and supported by the tray upstream frame 42 described earlier. On the other hand, a plurality of the curved surfaces 16c are supported in their nearly entire regions by the tray downstream frame 43 having a curvature equal to that of the curved surfaces 16c. The extension of the tray downstream frame 43 in the X and Y directions bridges the gaps between the curved surfaces arranged in the X direction. Thereby, even when a sheet S of any size other than a standard size is delivered, the leading end of the sheet S is infallibly supported by the curved surface 16c or the tray downstream frame 43. In this manner, irrespective of the size of the discharged sheet S, an adequate reduction in the risk of giving rise to damage and/or buckling is made possible.
In the present embodiment, the conveyance distance of the combination of the inclined surface 16a and the curved surface 16c is about 620 mm, and the inclination θ of the inclined surface 16a is 30°. This enables stacking and holding of even sheets of a large size such as an AO standard size (1189 mm long) on the tray unit 103 without slipping-off.
Each of the upper guides 17 is placed to face the corresponding inclined surface 16a of the stacking tray 16 with a predetermined interval between them, and a plurality of guide rollers 18 are placed at equal intervals in the extension direction of the upper guide 17. Each of the guide rollers 18 has a roller 18b which is a rolling element rotated with making direct contact with the sheet S and an arm 18a supporting the roller 18b. The arm 18a is rotatable with one end attached to the upper guide 17. The rotating center of the arm 18a is located upstream of the roller 18b. In this way, the upper guide 17 has a structure including a plurality of driven rolling elements that are retracted by rotation of the arms upon being pushed by the sheet and are arranged in the sheet-conveyance direction. Thus, even when the number of sheets stacked is increased to decrease the distance between the top sheet and the upper guide 17, the driven rolling elements are pushed by the incoming sheet to move away, so that a sheet jam is hardly caused, leading to smooth stacking of sheets.
The stoppers 44 maintain a constant sheet-feeding interval Lt0 between upper guide sheet-feeding surfaces 17a of the main bodies of the upper guides 17 and the inclined surfaces 16a of the stacking trays 16 facing the surfaces 17a. The upper guides 17 operate to promote the conveyance of the sheet S while reducing the curl to achieve the sheet stacking in a predetermined posture. To meet this need, the sheet-feeding interval Lt0 is desirably controlled to the extent that the leading end of the incoming sheet S does not curl between the stacking trays 16 and the upper guides 17, that is, to be a distance smaller than a minimum diameter which may be shown by a curled sheet S. In this respect, when the sheet S is held in a roll form as described in
On the other hand, each of the guide rollers 18 attempts to rotate in a vertically downward direction (Z direction) because of the weight of the roller 18b, but an unillustrated stopper inhibits the guide roller 18 from rotating beyond a predetermined position. As a result, when conveyance is not performed, the guide roller 18 keeps the posture illustrated in
Preferably, the gap distance Lt1 is a height which keeps the roller 18 from making contact with the top sheet of the stacked sheets Sa even when the number of sheets stacked increases to the maximum. In the present embodiment, assuming that the thickness of the sheet S is 0.1 mm and the maximum value of the number of sheets is 100, the gap distance Lt1 is adjusted to be a value equal to or larger than 0.1×100=10 mm.
However, if the downstream end 17b of the upper guide 17 is located farther upstream than necessary, adverse effects may be produced on conveyance in an inoperative region of the function of the upper guide 17.
To avoid this, in the present embodiment, the location of the downstream end 17b of the upper guide 17, that is, the length of the upper guide 17 is adjusted to the extent that neither of a collision of the leading end of the sheet S shown in
Referring to
Referring back to
On each curved surface 16c extending at a predetermined curvature from the inflection point 16b to the distal end 16f, the distal end 16f preferably extends beyond a top point 16e in the Z direction of the curvature surface 16c. This is because, if the distal end 16f is located closer to the inflection point 16b rather than the top point 16e, a force is locally applied to the underside of the hanging sheet S at the position of the distal end 16f, increasing the risk of leaving a bend. On the other hand, the range of the curved surface 16c with a curvature being able to suitably support the hanging sheet S on its surface is up to a position 16g at which a tangential line of the curved surface 16c becomes vertical. Even if the curved surface 16c extends beyond this position, the curved surface 16c is incapable of supporting the sheet hanging downward in the vertical direction. That is, it is sufficient that the distal end 16f of the curved surface 16c extends to the position 16g at the maximum. In the present embodiment, the inclined surface 16a is described as a flat surface without a curvature, but it can be designed as a curved surface with a less steep curvature than the curved surface 16c.
As explained above, in the stacker 101 a plurality of the clamp guides 14 are arranged in the width direction of the sheet S to be capable of moving forward and backward in such a manner as to block the level difference gap H to the stacking trays 16. The amount of travel is controlled for each of the clamp guides 14 such that the extent of travel of the clamp guide 14 differs depending upon the stacking amount of the sheets already stacked on the stacking trays 16. As a result, the level difference gap H to the stacking tray 16 or the stacked sheet Sa can be blocked in any position of the width direction regardless of sizes of the already stacked sheets to prevent the leading end of the incoming sheet S newly conveyed from entering into the level difference gap H.
In addition, the stacker 101 places the stacking tray 16 formed of the inclined surface 16a for carrying in and conveying the sheet S and the curved surface 16c having a larger curvature than that of the inclined surface 16a for receiving the sheet S from the inclined surface 16a and conveying it. The upper guide 17 is placed in a predetermined position to face only the inclined surface 16a for reducing the curl of the sheet S conveyed on the stacking tray 16. As a result, it is possible to provide the stacker that can smoothly discharge, and orderly stack and hold a plurality of the sheets S while reducing the curl of the sheets S during the conveyance.
(Modifications)Hereinafter, some of modifications will be explained.
The clamp guides 14 respectively are held by holders 25, and a plurality of the holders 25 are connected through the common clamp-guide shaft 30 to the camp-guide motor 28. The gears 26 rotate in a forward or backward direction by a drive of the clamp-guide motor 28 to move the guide cases 14b forward or backward in the Y direction through the guide rails 32 meshing with the gears 26.
The guide case 14b moves in the Y direction by a distance in accordance with a drive amount of the clamp-guide motor. However, when the roller 24 attached on the leading end of the guide plate 14a collides with the stacked sheets S or the stacking tray 16, the guide plate 14a compresses the spring 33 according to the received reaction and attempts to return back into the guide case 14b. As a result, as similar to the precedent embodiment, in a plurality of the clamp guides 14 arranged in the X direction, the extent of the travel differs in accordance with the thickness of the stacked sheets in each position.
In this way, in the present modification also, the level difference gap to the stacking tray 16 or the stacked sheets Sa can be appropriately blocked in any position of the width direction (X direction) regardless of a size and amount of the already stacked sheets. As a result, the leading end of the incoming sheet S newly conveyed does not enter into the level difference gap, thus making it possible to realize the conveyance without a hitch.
When the roller 24 is rotated in the R1 direction in this structure, the rotation restricting member 83 is pushed up along the inclined portion 81a of the tooth face 81 and goes down along the wall portion 81b in a repetition manner. That is, while the state in
Hereinafter, there will be explained an operational effect when the roller 24 is attached to the leading end of the clamp guide 14 for use. When the roller 24 abuts on the stacking tray 16 or the stacked sheets Sa, that is, when the roller 24 transitions from the retract state to the projecting state, the roller 24 abuts thereon while moving forward in the Y direction. Therefore a force of causing the clamp roller 24 to rotate in the R1 direction acts on the clamp roller 24. The roller 24 can rotate only in the R1 direction. Accordingly as similar to the precedent embodiment, it is possible to reduce the curl while restricting the stacked sheets Sa from being misaligned in the Y direction without damaging the stacked sheets Sa.
On the other hand, in a state where the roller 24 is restraining the stacked sheets Sa, when the new sheet S is conveyed on the stacked sheets Sa, the stacked sheets Sa attempt to move forward in the Y direction with the friction force generated therebetween. At this time, a force of causing the clamp roller 24 to rotate in the R2 direction acts on the clamp roller 24. However, the roller 24 does not rotate in the R2 direction. Therefore it is possible to restrict the stacked sheets Sa from being misaligned in the Y direction to maintain the stacking position of the stacked sheets.
Next,
On the other hand,
While the present invention has been described with reference to exemplary embodiments, it is to be understood that the invention is not limited to the disclosed exemplary embodiments. The scope of the following claims is to be accorded the broadest interpretation so as to encompass all such modifications and equivalent structures and functions.
This application claims the benefit of Japanese Patent Application No. 2014-199753 filed Sep. 30, 2014, which is hereby incorporated by reference wherein in its entirety.
Claims
1. A sheet stacking apparatus, comprising:
- a tray on which a sheet is placed in an inclined condition; and
- a guide unit that guides a sheet conveyed on the tray and restrains an end of the sheet placed on the tray,
- wherein the guide unit comprises a plurality of movable guides which are divided in a width direction of the sheet and are movable in accordance with the sheet placed on the tray.
2. The sheet stacking apparatus according to claim 1, wherein
- a plurality of the divided movable guides respectively move by a driving force of a common driving unit such that a leading end of the guide abuts on the sheet placed on the tray or the tray.
3. The sheet stacking apparatus according to claim 2, wherein
- a torque limiter or a spring member is provided to correspond to each of a plurality of the divided movable members, wherein when the leading end abuts on the sheet or the tray, the movement of the guide unit is stopped by an operation of the corresponding torque limiter or spring member.
4. The sheet stacking apparatus according to claim 1, wherein
- a rolling element is attached on a leading end of each of a plurality of the divided movable guides, wherein the rolling element abuts on the sheet or the tray.
5. The sheet stacking apparatus according to claim 4, wherein
- the rolling element can be driven to be rotated only in one direction.
6. The sheet stacking apparatus according to claim 1, wherein
- the guide unit moves such that at the time when the leading end of the sheet is conveyed along the guide unit, the leading end of the guide is located in the projecting state of having moved to the tray-side, and at the time when the rear end of the sheet is conveyed along the guide unit, the leading end of the guide is located in the retract state of having retracted from the tray-side.
7. The sheet stacking apparatus according to claim 6, wherein
- at the time when the guide unit transitions from the projecting state to the retract state, at least one of the time of the transition, a speed of the transition and a conveyance speed of a sheet differs depending upon environment or sheet type.
8. The sheet stacking apparatus according to claim 6, further comprising a discharge roller for discharging the sheet conveyed by a conveyance unit to the tray,
- wherein the discharge roller holds the sheet together with the guide unit at the time the guide unit is in the projecting state, and holds the sheet together with the conveyance unit at the time the guide unit is in the retract state.
9. The sheet stacking apparatus according to claim 1, wherein
- the tray includes an inclined surface and a curved surface, wherein the sheet conveyed to the tray goes up in the upward direction against gravity along the inclined surface, hangs downward via the curved surface, and is placed on the tray.
10. The sheet stacking apparatus according to claim 9, further comprising an upper guide facing the inclined surface to have a predetermined interval therefrom,
- wherein a plurality of driven rolling elements are arranged along the sheet conveyance direction on the upper guide.
11. A sheet stacking apparatus in which a sheet is supported in an inclined condition by a tray, and a part of the sheet is stacked in a hanging-downward condition from the tray,
- wherein the tray includes an inclined surface and a curved surface, wherein the sheet conveyed to the tray goes up in the upward direction against gravity along the inclined surface and hangs downward via the curved surface,
- an upper guide facing the inclined surface to have a predetermined interval therefrom is provided, wherein the upper guide is not faced the curved surface or faced a part of the curved surface in having an interval larger than the predetermined interval.
12. The sheet stacking apparatus according to claim 11, wherein
- an end of the upper guide in a direction where the sheet is conveyed is positioned upstream of a boundary between the inclined surface and the curved surface in the conveyance direction.
13. The sheet stacking apparatus according to claim 12, wherein
- the sheet is pulled out from a roll sheet around a roll core of which the sheet is wound, and
- a distance from the boundary to the end in the travel direction of the sheet is smaller than 1.2 times a diameter of an outer periphery of the roll core.
14. The sheet stacking apparatus according to claim 11, wherein
- the sheet is pulled out from a roll sheet around a roll core of which the sheet is wound, and
- the predetermined interval is a distance smaller than a radius of curvature of an outer periphery of the roll core.
15. The sheet stacking apparatus according to claim 11, wherein
- the sheet is pulled out from a roll sheet around a roll core of which the sheet is wound, and
- a radius of curvature of the curved surface is larger than a radius of curvature of an outer periphery of the roll core.
16. The sheet stacking apparatus according to claim 11, wherein
- a plurality of driven rolling elements which retract when pushed by the sheet are provided to be arranged along the sheet conveyance direction on the upper guide.
17. The sheet stacking apparatus according to claim 11, wherein
- a friction member is attached in the vicinity of the distal end of the curved surface.
18. The sheet stacking apparatus according to claim 11, wherein
- the inclined surface comprises a plurality of inclined surfaces which are divided in the width direction of the sheet.
19. The sheet stacking apparatus according to claim 1, wherein
- the sheet comprises a plurality of sheets, which are printed by an inkjet printer to be conveyed and stacked on the tray.
Type: Application
Filed: Sep 21, 2015
Publication Date: Mar 31, 2016
Inventors: Naoki WAKAYAMA (Kawasaki-shi), Shuichi Masuda (Yokohama-shi), Takakazu Ohashi (Kawasaki-shi), Ryohei Maruyama (Kawasaki-shi)
Application Number: 14/859,557