1. Technical Field The present invention relates to a sheet ejection device that stacks sheets and divides the sheets into plural sets while stacking by setting the sheets off alternately (forward and backward) along an ejection direction of the sheets.
2. Background Arts
Recently, a great large number of print sheets are used for printing and copying in printers (such as inkjet printers, stencil printers and laser printers) and copiers. A Japanese Patent Application Laid-Open No. H10-109808 discloses a sheet ejection device used in such printers and copiers. According to the disclosed sheet ejection device, a large number of sheets can be stacked orderly and uniformly.
The sheet ejection device, although it is not shown by drawings, includes a bottom plate, an end plate, a pair of side fences extending along a sheet ejection direction and faced to each other, fins provided on the side fences, respectively, and guide members swingably provided on the side fences vertically, respectively, in order to stack a large number of sheets orderly.
A condition of sheets to be ejected varies due to a change of their environment, and thereby dropping behaviors of ejected sheets may become unstable. Therefore, the ejected sheers may be damaged when ejected, and stacking alignment of the ejected sheets may degrade.
Specifically, in a case of sheets having a light bias weight and a small size (e.g. bias weight: 60 g/m2 or less and size: B5) under a hot and humid condition (e.g. temperature: 30° C. and humidity: 70% or less), contact frictions with the side fences become large while the sheets are dropping off and balancing between both side edges of the sheets becomes hard to be kept well. Therefore, the sheets may lean on one of the side fences, and thereby the damages of sheets and the degradation of stacking alignment may easily occur.
On the other hand, in a case of sheets having a light bias weight and a small size (e.g. bias weight: 60 g/m2 or less and size: B5) under a cold and dry condition (e.g. temperature: 10° C. and humidity: 40% or less), contact frictions with the side fences become large while the sheets are dropping off and contact areas between dropping sheets and the side fences are large, so that the sheets may be drawn to one of the side fences due to electrostatic charge (e.g. almost 10 kV) of the dropping sheet. Therefore, the sheets may lean on the side fence, and thereby the damages of sheets and the degradation of stacking alignment may easily occur.
An object of the present invention is to provide a sheet ejection device that can provide superior sheet ejection performance without affected by its environment.
An aspect of the present invention provides a sheet ejection device that includes a sheet tray on which ejected sheets are stacked; a pair of side fences for restricting positions of the ejected sheets along a lateral direction perpendicular to an ejection direction; and at least one rib is formed vertically on each inner side of the side fences, wherein the ribs are configured to contact with side edges of each of the ejected sheets while the each of the ejected sheets falls down to the sheet tray to align the ejected sheet along the lateral direction.
According to the above aspect, both side edges of each of the ejected sheets contact with the ribs on the side fences while the each of the ejected sheets falls down to the sheet tray, and thereby the each of the ejected sheet can be aligned along the lateral direction. Therefore, an attitude of the each of the ejected sheets can be corrected adequately by the ribs, and then stacked on the sheet tray after its lateral position is aligned correctly. As a result, superior sheet ejection performance can be provided without affected its environment such as humidity. In addition, a drop speed of each of the ejected sheets contacting with the ribs becomes faster that contacting with both inner surfaces of the side fences. Therefore, the number of ejection sheets per unit time can be made larger because the next sheet ejection can be done earlier.
Hereinafter, an embodiment will be explained with reference to the drawings. In the drawings, an identical or equivalent component is indicated by an identical reference number. Note that the drawings show components schematically, and it should be considered that the components in the drawings are not shown precisely as they are. In addition, actual dimensions of the components and actual dimensional proportions among the components may be shown differently in the drawings.
Further, the embodiment described below is explained as an example that specifically carries out the subject matter of the present invention. In addition, materials, shapes, structures, arrangements of the components are not limited to those in the embodiment. The embodiment may be modified within the scope of the claims (e.g. arrangement of the components may be changed from the embodiment).
Furthermore, the sheet ejection device can adapt to any size of sheets. Although sheets are printed by stencil printing or by inkjets in the following descriptions, they can be printed by other methods. A printing method is not limited.
In the following descriptions, “right” and “left” are used based on a viewpoint from a downstream side of a sheet ejection direction U (i.e. viewed counter to a sheet ejection flow), as indicated in
The sheet set dividing unit 1 in the sheet ejection device 8 includes an ejection unit 10, a tray elevating mechanism 20, a pair of laterally-restricting plates (side fences) 31 and 32 for laterally restricting the sheets P stacked on a sheet tray 21, and a laterally-restricting plate shifting mechanism (side fence shifting mechanism) 30. The ejection unit 10 sequentially ejects sheets P supplied from the image forming apparatus along the sheet ejection direction U. The tray elevating mechanism 20 receives the sheets P that are sequentially ejected and then dropped off onto a sheet tray 21 to stack the ejected sheets P on the sheet tray 21, and shifts the sheet tray 21 vertically according to the number of the sheets P stacked on the sheet tray 21. The laterally-restricting plate shifting mechanism 30 shifts the laterally-restricting plates 31 and 32 along a lateral direction perpendicular to the sheet ejection direction U according to a size (lateral width) of the ejected sheets P. The sheet set dividing unit 1 further includes an offset guide plate shifting mechanism 50 and an end plate shifting mechanism 80.
The offset guide plate shifting mechanism 50 shifts an offset guide plate (guide fence) 52 and a first sheet aligning plate 53 (see
The end plate shifting mechanism 80 shifts an end plate (end fence) 82 and a second sheet aligning plate 97 (see
In addition, the sheet ejection device 8 further includes a controller 100 for controlling the above-explained components. An installation position of the controller 100 is not limited. The controller 100 may be provided integrally with a controller of the image forming apparatus, or may be provided integrally with a controller that controls an entire of the sheet ejection device 8. Further, the controller 100 may be disposed at an arbitrary position in the sheet set dividing unit 1.
Here, the sheet tray 21 can be shifted vertically while keeping its horizontal attitude, and the sheets P stacked on the sheet tray 21 are divided into plural sets (staggered forwardly and backwardly) by the offset guide plate 52 (that restricts the trailing edges of the sheets P), the end plate 82 (that restricts the leading edges of the sheets P) and the pair of laterally-restricting plates 31 and 32 (that restricts the sheets P laterally). Namely, the sheets P stacked on the sheet tray 21 are divided into plural sets (staggered alternately forward and backward) while they are surrounded by these four plates 31, 32, 52 and 82. The plates 31, 32, 52 and 82 are provided separately (independently) from the sheet tray 21.
(Ejection Unit 10)
The ejection unit 10 is attached to an upper portion of an uppermost rear panel 2 of the sheet set dividing unit 1. In the ejection unit 10, two pairs of sheet feed rollers 11 and an ejection roller 12 are provided along a sheet guide plate 13. The two pairs of sheet feed rollers 11 sequentially feed the sheets P supplied from the image forming apparatus. The ejection roller 12 is disposed at a sheet ejection position.
In addition, a pair of first wing members 5L and 5R and a pair of second wing members 6L and 6R are provided on both sides of the sheet guide plate 13, respectively. The first wing members 5L and 5R are made of metal, and each of their downstream end faces has an almost triangle shape. The first wing members 5L and 5R are disposed symmetrically with respect to a central line (along the sheet ejection direction U) of the sheet guide plate 13. The second wing members 6L and 6R are also made of metal, and each of their downstream end faces has an almost trapezoidal shape. The second wing members 6L and 6R are also disposed symmetrically with respect to the central line of the sheet guide plate 13.
An upper face of the first wing member 5L (5R) is made inclined to form a continuous surface together with an upper inclined face of the second wing member 6L (6R). The wing members 5L and 6L can be moved vertically by a drive mechanism (not shown) in synchronization with the wing members 5R and 6R, so that the height level of the wing members 5L and 6L (5R and 6R) can be adjusted to make the sheet P slightly curved. When the sheet P is slightly curved, the sheet P hardly sags down loosely and hardly waves during its ejection. Therefore, an adequate curvature for the sheet P can be variably formed by the wing members 5L, 5R, 6L and 6R according to a size of the sheet P.
In the present embodiment, the ejection unit 10 is provided on the sheet set dividing unit 1 to set the ejection position of the sheet P precisely. However, the ejection unit 10 including the same configuration as explained above may be provided on the image forming apparatus to eject sheets P sequentially from the image forming apparatus to the sheet set dividing unit 1.
(Tray Elevating Mechanism 20)
In the tray elevating mechanism 20, the sheet tray 21 is disposed horizontally between the rear panels 2 of the sheet set dividing unit 1 and a front panel 3 distanced from the rear panels 2. Its drive mechanism (not shown) for elevating the sheet tray 21 is disposed on a right side of the sheet tray 21. The sheet tray 21 includes a front end 21a on a downstream side along the sheet ejection direction U, a rear end 21b on an upstream side along the sheet ejection direction U, a left-side end 21c and a right-side end (not shown) parallel to the left-side end 21c, and has a rectangular shape in its plan view.
In addition, the sheet tray 21 further includes a bottom center stem 21p and bottom ribs 21q and 21r. The bottom ribs 21q are aligned on the left side, and each of them extends from the left side toward the bottom center stem 21p. The bottom ribs 21r are aligned on the right side, and each of them extends from the right side toward the bottom center stem 21p. The bottom center stem 21p is disposed at a center between the left-side end 21c and the right-side end along the sheet ejection direction U, and has a flat upper surface 21e. Each of the bottom ribs 21q has an inclined upper surface 21f that is made gradually higher toward the left-side end 21c. Each of the bottom ribs 21r has an inclined upper surface 21g that is made gradually higher toward the right-side end. By the inclined upper surfaces 21f and 21g, the above-explained curvature is formed on the sheets P stacked on the sheet tray 21.
About four thousand of sheets P having an identical size such as A3 and A4 can be stacked on the sheet tray 21 (on the upper surfaces 21e, 21f and 21g). Therefore, a movable vertical range of the sheet tray 21 is set to about 400 to 500 mm.
In addition, a pair of inner vertical brackets 22 and 23 is attached at the right side of the sheet tray 21 to form a distance therebetween. Further, a pair of outer vertical brackets 22B and 23B is vertically provided outside the pair of the inner vertical brackets 22 and 23. The pair of outer vertical brackets 22B and 23B is also attached to the right side of the sheet tray 21. Two reinforcement rods 24 are provided between the pair of outer vertical brackets 22B and 23B (lower one is not shown in
Furthermore, as shown in
As shown in
While the sheets P are sequentially ejected from the ejection unit 10 (or supplied from the image forming apparatus) and then drop off onto the sheet tray 21, the controller 100 controls the stepping motor 25 to shift the height level of the sheet tray 21 based on the detection results of the optical sensors 29 so that a sheet drop height H (see
(Laterally-Restricting Plates 31 and 32, and Laterally-Restricting Plate Shifting Mechanism 30)
As shown in
Since the laterally-restricting plates 31 and 32 have symmetrical shapes to each other, only the laterally-restricting plate 32 will be explained hereinafter as a representative of them, and explanations for the laterally-restricting plate 31 will be omitted.
The laterally-restricting plate 32 includes a frame 35. In the frame 35, plural walls 32a to 32d are extended vertically, and each of the walls 32a to 32d integrally connects an upper bar with a middle bar of the frame 35. A window W is formed between each adjacent pair of the walls 32a to 32d. In the frame 35, feet F are integrally extended downward from the center bar, and the feet F are almost associated with the walls 32a to 32d, respectively. Each width of the feet F along the sheet ejection direction U and a distance between each adjacent pair of the feet F are set so as to the feet F are located in some interspaces between the bottom ribs 21r on the sheet tray 21. When the laterally-restricting plate 32 is shifted laterally by the laterally-restricting plate shifting mechanism 30, the feet F laterally shifted in the some interspaces between the bottom ribs 21r.
On inner surfaces of some of the feet F, vertical ribs La and Lb are formed. In the present embodiment, the ribs La and Lb are formed on two of the feet F disposed on a near side to the ejection unit 10 (on an upstream side along the sheet ejection direction U). The ribs La and Lb are vertically extended from the foot F to an uppermost edge of the frame 35 through the walls 32a and 32b. No ribs are formed on inner surfaces of the walls 32c and 32d on a far side from the ejection unit 10 (on a downstream side along the sheet ejection direction U) and the foot F under the walls 32c and 32d, but the walls 32c and 32d and the foot F under the walls 32c and 32d forms a flat surface S. The flat surface S and ridges Lt (see
As shown in
In addition, some of the feet F include extension members B at their lower ends, respectively (see back face of the laterally-restricting plate 31 on the left in
On the other hand, the laterally-restricting plate shifting mechanism 30 is attached to a top panel (not shown) disposed above the sheet set dividing unit 1 so as to cover the sheet set dividing unit 1. Namely, a first motor 34 is attached to a first motor bracket 33R, and the first motor bracket 33R is fixed to the top panel. Note that the first motor 34 can be rotated forwardly and reversely.
The rotation of the first motor 34 is transmitted to a first timing pulley (not shown) fixed on an output shaft of the first motor 34. Further, a first timing belt 38 is wound around the first timing pulley and a second timing pulley 37 rotatably attached to a bracket 33L paired with the above-mentioned motor bracket 33R. The bracket 33L is also attached to the top panel. Two guide shafts 39 and 40 are disposed parallel to the extended first timing belt 38 with interposing the first timing belt 38 therebetween.
A first hanger 41 is fixed with the laterally-restricting plate 31 on the left, and a second hanger 42 is also fixed with the laterally-restricting plate 32 on the right. The first hanger 41 is slidably coupled with the guide shafts 39 and 40. The second hanger 42 is also slidably coupled with the guide shafts 39 and 40. The first hanger 41 is fixedly connected with a rear-side path of the first timing belt 38 near the laterally-restricting plate 31. The second hanger 42 is fixedly connected with a front-side path of the first timing belt 38 near the laterally-restricting plate 32.
When the first timing belt 38 is driven forwardly by driving the first motor 34 forwardly, the first and second hangers 41 and 42 are moved inward toward each other. Therefore, the laterally-restricting plates 31 and 32 are shifted toward each other to narrow the lateral distance therebetween. On the other hand, when the first timing belt 38 is driven reversely by driving the first motor 34 reversely, the first and second hangers 41 and 42 are distanced away from each other. Therefore, the laterally-restricting plates 31 and 32 are distanced from each other to widen the lateral distance therebetween. In this manner, the lateral distance between the laterally-restricting plates 31 and 32 can be adjusted according to the size (lateral width) of the stacked sheets P to restrict the stacked sheets P laterally.
(Offset Guide Plate Shifting Mechanism 50)
The offset guide plate shifting mechanism 50 configures one of featured portions in the present embodiment. The offset guide plate shifting mechanism 50 is unitized and attached to the uppermost rear panel 2 just beneath the ejection unit 10 (or the image forming apparatus) so that the sheets P sequentially ejected from the ejection unit 10 (or the image forming apparatus) can drop off onto the sheet tray 21.
Hereinafter, the offset guide plate shifting mechanism 50 will be explained with reference to
The offset guide plate 52 includes a top plate 52a having a narrow width, a front guide plate 52b for restricting trailing edges of the stacked sheets P on the sheet tray 21 to set a set(s) of the stacked sheets P off, and a left-side plates 52c extended rearward from the left-side edge of the front guide plate 52b. In addition, a lower center portion of the front guide plate 52b is cutout to form a cutout 52b1. The above-mentioned first sheet aligning plate 53 made of a sheet metal is held in the cutout 52b1. The first sheet aligning plate 53 is weighed down with its own weight to extend just behind the rear end 21b of the sheet tray 21, or to contact its lower end with the uppermost sheet P of the stacked sheets P on the sheet tray 21
The first sheet aligning plate 53 is configured to align the trailing edges of the stacked sheets P on a front face of the front guide plate 52b. Rounded protrusions 53a are formed at both lateral ends and the center of the lower edge of the first sheet aligning plate 53, so that the first sheet aligning plate 53 can be softly contacted with the uppermost sheet P of the stacked sheets P to restrict a trailing edge of a sheet P to be stacked next together with the front guide plate 52b. Therefore, no gap is formed between the offset guide plate 52 and the uppermost sheet P when the first sheet aligning plate 53 contacts with the upper most sheet P of the stacked sheets P to divide the stacked sheets P into plural sets as explained later in detail, so that it become possible to restrict the trailing edge of the sheet P to be stacked next, and surfaces of the sheets P never be damaged.
In addition, a tension spring 65 is set between a lower potion of the front late 51a of the first bracket 51 and an operation support unit 49 disposed beside the side plates 51c as explained later in detail. Further, a drive motor 56 that can be rotated forwardly and reversely is attached to a bottom of a motor bracket 55, and the offset guide plate 52 is shifted by the drive motor 56. Furthermore, the side plate 51c of the first bracket 51 and after-explained rotational shafts 66 and 67 are linked by after-explained upper and lower link members 68 and 89 and a link plate 72. By this link mechanism, the offset guide plate 52 can be shifted, integrally with the first sheet aligning plate 53, almost along the sheet ejection direction U (also shifted downward).
Specifically, as shown in
Between the side plates 51c of the first bracket 51 and the left-side plates 52c of the offset guide plate 52, one end of the above-mentioned link member 68 is fixed with the upper rotational shaft 66. Another end of the link member 68 is pivotally attached to a pivot point 70 at an upper corner of the left-side plates 52c. Similarly, one end of the above-mentioned link member 69 is fixed with the lower rotational shaft 67. Another end of the link member 69 is pivotally attached to a pivot point 71 at a lower corner of the left-side plates 52c. An upper short link member 68B is fixed with the upper rotational shaft 66 outside the side plate 51c. Similarly, a lower short link member 69B is fixed with the lower rotational shaft 67 outside the side plates 51c. The above-mentioned link plate 72 links ends of the short link members 68B and 69B at pivot points 73 and 74, respectively, to synchronize rotational angles of the rotational shafts 66 and 67.
Therefore, when the upper rotational shaft 66 is rotated by the drive motor 56 via the gears 57, 59, 61, 63 and 63u, the lower rotational shaft 67 is passively rotated by the links 68B, 69B and 72. In addition, when the rotational shafts 66 and 67 are synchronously rotated forwardly (clockwise in
According to the above-explained link mechanism, a maximum shift stroke of the offset guide plate 52 along the sheet ejection direction U is almost 30 mm, and a vertical shift stroke is almost 10 mm. Therefore, when dividing the sheets P into plural sets, the offset OS (see
Namely, in the above-explained offset guide plate shifting mechanism 50, the offset guide plate 52 and the first sheet aligning plate 53 restrict the trailing edges of the sheets P according to the offset OS regardless of the size (length along the sheet ejection direction U) of the sheets P. Therefore, the offset guide plate shifting mechanism 50 can reduce costs by integrally shifting the offset guide plate 52 and the first sheet aligning plate 53 by the predetermined offset OS when dividing the sheets P into each set.
(End Plate Shifting Mechanism 80)
The end plate shifting mechanism 80 also configures one of featured portions in the present embodiment. The end plate shifting mechanism 80 is unitized and provided on a side of the front end 21 a of the sheet tray 21. Hereinafter, the end plate shifting mechanism 80 will be explained with reference to
As explained above, the end plate 82 can be shifted along the sheet ejection direction U, but the end plate 82 cannot be shifted vertically. Since the sheet tray 21 is elevated according to the number of the stacked sheets P when dividing the sheets P into plural sets, the end plate 82 is kept at a fixed height level higher than the upper surface 21e of the sheet tray 21. The end plate shifting mechanism 80 (the shifting mechanism for shifting the second bracket 81 and the end plate 82 integrally) is attached to the top panel (not shown) disposed above the sheet set dividing unit 1 so as to cover the sheet set dividing unit 1. Namely, a second motor 84 is attached to a second motor bracket 83, and the second motor bracket 83 is fixed to the top panel. Note that the second motor 84 can be rotated forwardly and reversely.
The rotation of the second motor 84 is transmitted to a third timing pulley 86 fixed on an output shaft of the second motor 84. Further, a second timing belt 88 is wound around the third timing pulley 86 and a fourth timing pulley 87 rotatably attached to the upper portion of the uppermost rear panel 2. Two guide shafts 89 and 90 are disposed parallel to the extended second timing belt 88 with interposing the second timing belt 88 therebetween.
A third hanger 91 (see
When the second timing belt 88 is driven forwardly by driving the second motor 84 forwardly, the third hanger 91 is moved toward the offset guide plate 52. Therefore, the second bracket 81 and the end plate 82 are integrally shifted to set the sheets P off backwardly. On the other hand, when the second timing belt 88 is driven reversely by driving the second motor 84 reversely, the third hanger 91 is distanced away from the offset guide plate 52. Therefore, the second bracket 81 and the end plate 82 are shifted to set the sheets P off forwardly. In this manner, the offset OS for the sheets P can be set forwardly (+) or reversely (−) by restricting leading edges of the stacked sheets P.
As shown in
In addition, the second sheet aligning plate 97 made of a sheet metal is slidably coupled with the second bracket 81 on the front side of the second bracket 81. An upper end of the second sheet aligning plate 97 is hooked with a roller 96a rotatably attached to another end of the lever 95 via a rotational axis 96b. The second sheet aligning plate 97 includes a pair of sheet aligning arms 97p made of resin at its lower ends, so that the second sheet aligning plate 97 can be softly contacted with the uppermost sheet P of the stacked sheets P to restrict a leading edge of a sheet P to be stacked next. Further, the second sheet aligning plate 97 includes a shading plate 97a at its upper end and an optical sensor 98 is attached to the front plate 81b of the second bracket 81 to detect the vertical position of the second sheet aligning plate 97.
When the electromagnetic solenoid 93 is de-energized as shown in
On the other hand, when the electromagnetic solenoid 93 is energized to swing the lever 95 upward by the movable iron core 93a as shown in
Namely, in the above explained end plate shifting mechanism 80, the end plate 82 and the second sheet aligning plate 97 restrict the leading edges of the sheets P according to the above-explained offset OS and the size (length along the sheet ejection direction U) of the sheets P. Therefore, the end plate shifting mechanism 80 integrally shifts the end plate 82 and the second sheet aligning plate 97 by the second motor 84 by the predetermined offset OS when dividing the sheets P into each set. And the end plate shifting mechanism 80 shifts the second sheet aligning plate 97 upward by the energization of the electromagnetic solenoid 93, and shifts the second sheet aligning plate 97 downward by the de-energization of the electromagnetic solenoid 93.
In the present embodiment, the electromagnetic solenoid 93 is used as the upward shifting mechanism for shifting the second sheet aligning plate 97 upward. However, the upward shifting mechanism is not limited to the electromagnetic solenoid 93, and may have another mechanism as long as it can softly contact the second sheet aligning plate 97 with the uppermost sheet P of the stacked sheets P. For example, a piezo-stack actuator or a motor may be used as the upward shifting mechanism.
(Controller 100)
As shown in
(Operations For Dividing Sheets Into Sets)
Hereinafter, operations for dividing the sheets P sequentially ejected from the ejection unit 10 (or the image forming apparatus) into plural sets on the sheet tray 21 will be explained step by step with reference to
In addition, when dividing the sheets P sequentially ejected from the ejection unit 10 (or the image forming apparatus) into plural sets by setting sheet sets off alternately (forwardly and backwardly), the predetermined number of the sheets P in a single set may be set to a constant value for each set, or may be set differently (variously) for each set according to print jobs or the like. Further, when setting sheet sets off alternately (forwardly and backwardly), a first stacking position (backward offset position) and a second stacking position (forward offset position) can be set, and the two positions are set alternately.
Here, the first stacking position is a position where the offset guide plate 52 and the end plate 82 are set at their upstream (backward) positions (i.e. their waiting positions), respectively. In other words, when the offset guide plate 52 and the end plate 82 are set at their waiting position, the sheets P are stacked at the first stacking position (see
As shown in
In addition, the offset guide plate 52 provided on a side of the rear panels 2 is located at a height level higher than the upper surface 21e of the sheet tray 21. The offset guide plate 52 is slightly distanced from the rear end 21b of the sheet tray 21 and almost flat with the uppermost rear panel 2 to restrict the trailing edges of the sheets P for the first dividing operation of the sheets P. The first sheet aligning plate 53 attached to the lower portion of the offset guide plate 52 is weighed down with its own weight to restrict the trailing edges of the sheets P together with the offset guide plate 52.
Further, the end plate 82 provided on a side of the front panel is moved backward so that the distance between the end plate 82 and the rear panel 2 (i.e. the retracted offset guide plate 52) is made almost equivalent to (or slightly wider than) the length of the sheets P to be stacked on the sheet tray 21. Namely, the end plate 82 is set at a position associated with the size (length along the sheet ejection direction U) of the sheets P to be stacked on the sheet tray 21 to restrict the leading edges of the sheets P for the first dividing operation of the sheets P. Furthermore, the end plate 82 is located at a height level higher than the upper surface 21e of the sheet tray 21. The second sheet aligning plate 97 attached to the lower portion of the end plate 82 is weighed down with its own weight (the electromagnetic solenoid 93 is de-energized) and the sheet aligning arms 97p at the lower ends of the second sheet aligning plate 97 are softly contacted with the upper surface 21e to restrict the leading edges of the sheets P together with the end plate 82.
Subsequently, as shown in
The sheets P sequentially ejected from the ejection unit 10 (or the image forming apparatus) fall down between the rear panel 2 (the retracted offset guide plate 52) and the end plate 82, and thereby are sequentially stacked on the sheet tray 21. Here, the leading edges of the sheets P are aligned (restricted) by the second sheet aligning plate 97. The sheet level SL is continuously detected by the optical sensors 29, and the sheet tray 21 is shifted downward by the tray elevating mechanism 20 to keep the sheet drop height H constant. According to this downward shifting of the sheet tray 21, the second sheet aligning plate 97 becomes separated from the upper surface 21e. When the predetermined number of the sheets P are stacked on the sheet tray 21 as the first divided sheet set, the downward shifting of the sheet tray 21 is stopped and the first sheet dividing operation is finished.
Subsequently, as shown in
The offset guide plate 52 is protruded from the uppermost rear panel 2, and stopped in a state where the lower end of the first sheet aligning plate 53 is contacted with the uppermost sheet P of the first divided sheet set. The offset OS of the offset guide plate 52 (the first sheet aligning plate 53) for the second sheet dividing operation is set to +30 mm. Here, the first sheet aligning plate 53 is softly contacted with the uppermost sheet P at a forward position from the trailing edges of the sheets P of the first divided sheet set, but the uppermost sheet P never got misaligned forward because of the restriction by the second sheet aligning plate 97.
Subsequently, as shown in
Subsequently, as shown in
The offset OS of the end plate 82 (the second sheet aligning plate 97) for the second sheet dividing operation is set to +30 mm, similarly to the offset OS of the offset guide plate 52 (the first sheet aligning plate 53). The second sheet aligning plate 97 is positioned forward from the leading edges of the sheets P of the first divided sheet set, and the lower ends of the sheet aligning arms 97p are positioned at a height level lower than the uppermost sheet P of the first divided sheet set but not contacted with the sheet tray 21.
Subsequently, as shown in
The sheets P sequentially ejected from the ejection unit 10 (or the image forming apparatus) fall down between the offset guide plate 52 shifted forward and the end plate 82 shifted forward, and thereby are sequentially stacked on the first divided sheet set. The sheet level SL is continuously detected by the optical sensors 29, and the sheet tray 21 is shifted downward by the tray elevating mechanism 20 to keep the sheet drop height H constant. When the predetermined number of the sheets P are stacked on the first divided sheet set as the second divided sheet set, the downward shifting of the sheet tray 21 is stopped and the second sheet dividing operation is finished.
Subsequently, as shown in
Subsequently, as shown in
(Advantages)
According to the present embodiment, a sheet(s) P ejected from the ejection unit 10 of the sheet ejection device 8 contacts with the ribs La and Lb on the laterally-restricting plate 32 (31) at its side edge(s) PE extending along the sheet ejection direction U as shown in
In addition, a drop speed of a sheet P while its side edge(s) PE is aligned by the ribs La and Lb becomes faster that that while the side edge(s) PE is aligned by the flat surface(s) S. Therefore, a drop speed of a trailing edge of the sheet P (on a side of the ribs La and Lb) becomes faster than a drop speed of a leading edge of the sheet P (on a side of the flat surface(s) S). As a result, the side edge(s) PE can be aligned stably on a side of the trailing edge (on a side of the ribs La and Lb), and the number of ejection sheets per unit time can be made larger because the next sheet ejection can be done earlier.
In addition, the flat surface(s) S is formed on an inner surface(s) of the laterally-restricting plate (side fence) 32 (31) so that the flat surfaces S and the ridges Lt of the ribs La and Lb are on a single plane. Therefore, the side edge(s) PE on the side of the leading edge contacts with the flat surface S, so that inclination of the leading edge of the sheet P (the orientation of the leading edge becomes unparallel to the sheet ejection direction U) can be prevented while preventing reduction of the number of ejection sheets per unit time.
Further, each of the ribs La and Lb has the upstream surface Le gently inclined to the side edge PE of the sheet P as shown in
Furthermore, the ejection unit 10 can eject the sheets P while making them slightly curved to prevent them from sagging down loosely and waving, and can form an adequate curvature to various types of the sheets P. Therefore, the sheets P can be ejected after getting the adequate curvature according to the shapes, the positions and the number of the ribs La and Lb,
Note that the ribs La and Lb are aligned on an upstream side as rib formed on the inner surfaces of the laterally-restricting plates 32 and 31 in the present embodiment. By forming at least one rib on an upstream side on each of the laterally-restricting plates (side fences) 32 and 31, behaviors of the sheets P can be corrected by the ribs and then the sheets P can be stacked while laterally aligned precisely.
The present invention is not limited to the above-mentioned embodiment, and it is possible to embody the present invention by modifying its components in a range that does not depart from the scope thereof. Further, it is possible to form various kinds of inventions by appropriately combining a plurality of components disclosed in the above-mentioned embodiment. For example, it may be possible to omit several components from all of the components shown in the above-mentioned embodiment.
The present application claims the benefit of a priority under 35 U.S.C §119 to Japanese Patent Application No. 2012-191107, filed on Aug. 31, 2012, the entire content of which is incorporated herein by reference.
Number | Date | Country | Kind |
---|---|---|---|
2012-191107 | Aug 2012 | JP | national |