Patent Publication Number: US-6701841-B2

Title: Sheet discharge unit

Description:
BACKGROUND OF THE INVENTION 
     The present invention relates to a sheet discharge unit for transferring a sheet of pre-treated paper such as a printed paper toward a paper receiving tray and, more particularly, to a sheet discharge unit for use in a printing machine. 
     Considerable research and development work has been undertaken in the pasts to provide sheet discharge units, one typical example of which is shown in FIG.  15 . In FIG. 15, a sheet discharge unit  100  has a transfer passage  102  through which a sheet of printed paper  101  is conducted to a paper receiving tray  107 , and a pair of transfer belts  103 ,  103  are located at a center of the transfer passage  102 . The transfer belts  103 ,  103  move between a sheet transfer starting position and a sheet transfer terminating position. Also, a bottom wall  102   a  of the transfer passage  102  has a large number of suction bores  104  through which air remaining in the vicinity of the transfer passage  102  is drawn downward such that the sheet  101  is urged toward the transfer belt  103 . A pair of left and right jump wings  105 ,  105  are located in the sheet transfer terminating position at both sides of the transfer belts  103 ,  103 . The pair of jump wings  105 ,  105  are freely moveable in a pair of guide openings  106 , respectively, between a guide position (as shown in FIG. 15) in which the jump wings  105 ,  105  protrude upward from the bottom surface  102   a  and a wait position in which the jump wings  105 ,  105  are retracted downward from the bottom wall  102   a . An upper surface  105   a  of each jump wing  105  is gradually inclined upward along the sheet transfer direction and has a three-dimensional inclined profile wherein each jump wing  105  is gradually inclined from an inside toward an outside. The paper receiving tray  107  is located at a position downstream side of the sheet transfer terminating position and at a position lower than the sheet transfer terminating position. Side fences  108  are mounted at both sides of the paper receiving tray  107 , respectively, and an end fence is mounted at a distal end of the paper receiving tray  107 . 
     With such a structure, when the printed sheet  101  is conducted on the sheet transfer starting position of the transfer passage  102 , the printed sheet  101  is sucked with air toward the bottom surface  102   a  of the transfer passage  102  and is urged toward the transfer belts  103 ,  103 . The printed sheet  101  that is urged on the transfer belts  103 ,  103  is transferred to the sheet transfer terminating position by the transfer belts  103 . Here, when the printed sheet  101  to be transferred has a low rigidity, the pair of jump wings  105 ,  105  are moved to the guide position as shown in FIG.  15 . When this occurs, the printed sheet  101  is guided upward at both sides thereof with the pair of jump wings  105 ,  105  such that the printed sheet  101  is discharged under a state wherein both sides of the printed sheet  101  is curved upward from a central portion. Then, the printed sheet  101  has an increased apparent rigidity and traces a stable dropping trajectory to be dropped to the paper receiving tray  107 . In contrast, when the printed sheet  101  to be discharged has a strong rigidity, the pair of jump wings  105 ,  105  are located in the wait position. In this event, the printed sheet  101  is discharged in a stable dropping state owing to its property of strong rigidity. 
     Related technologies of the conventional sheet discharge unit  100  discussed above are disclosed in Japanese Patent Application Laid-Open Publication No. H6-239000. 
     SUMMARY OF THE INVENTION 
     In the conventional sheet discharge unit  100 , however, since the pair of left and right jump wings  105 ,  105  are laterally separate from one another with a sufficiently desired width to cope with printed sheets of various sizes and all of upper surfaces  105   a ,  105   a  of the jump wings  105 ,  105  tend to be brought into contact with surfaces of the printed sheets  101 , there exists a relatively large running resistance caused in the printed sheet  101 , resulting in a difficulty in discharging the printed sheet to a normal final dropping position. Also, when the printed sheet  101  has the large running resistance, a large amount of paper dust or paper powder is produced owing to wear of the paper. Particularly, the printed sheet  101  is forcedly curved on the left and right jump wings  105 ,  105  and, therefore, a large running resistance is applied to the printed sheet  101 . If, in this instance, the width of the left and right jump wings  105 ,  105  is decreased with a view to decreasing the running resistance, then, it becomes difficult for the sheet discharge unit to cope with the printed sheet of various sizes. 
     It is therefore an object of the present invention to provide a sheet discharge unit which can cope with sheets of paper of various sizes and which can reduce running resistance of the sheet of paper and the amount of paper dust or paper powder to be produced from the paper. 
     A sheet discharge unit of the present invention is provided with: a paper receiving tray; a transfer passage transferring a sheet of pre-treated paper to the paper receiving tray along a sheet transfer direction; guide openings formed at both sides of the transfer passage; a transfer member located in the transfer passage to impart a force to the sheet of pre-treated paper so as to move the sheet of pre-treated paper in the sheet transfer direction; jump wings respectively disposed in the guide openings, and having convex and concave portions arranged in a direction substantially perpendicular to the sheet transfer direction; and actuating member actuating the jump wings between a guide position in which the jump wings respectively protrude upward from the guide openings and a wait position in which the jump wings are retracted into the guide openings. 
     More specifically, according to one aspect of the invention, there is provided a sheet discharge unit having a transfer passage for transferring a sheet of pre-treated paper along a sheet transfer direction toward a paper receiving tray and having a bottom surface. The sheet discharge unit comprises a pair of left and right jump wings freely moveable between a guide position in which the jump wings protrude upward from the bottom surface of the transfer passage and a wait position in which the jump wings is retracted from the bottom surface of the transfer passage. Each of the left and right jump wings includes a plurality of divided wing components which are laterally spaced from one another in a direction perpendicular to the sheet transfer direction such that, when the jump wings remain in the guide position, the sheet of pre-treated paper is guided upward at both sides thereof to form a curved dropping state and is discharged to the paper receiving tray and, when the jump wings remain in the wait position, the sheet of pre-treated paper is not curved at the both sides thereof and is discharged to the paper receiving tray. 
     Besides, according to another aspect of the present invention, there is provided a sheet discharge unit having a transfer passage for transferring a sheet of pre-treated paper along a sheet transfer direction toward a paper receiving tray and having a bottom surface. The sheet discharge unit comprises a pair of left and right jump wings freely moveable between a guide position in which the jump wings protrude upward from the bottom surface of the transfer passage and a wait position in which the jump wings remain beneath the bottom surface of the transfer passage. Each of the left and right jump wings includes convex segments for guiding the sheet of pre-treated paper and concave recesses which are out of contact with the sheet of pre-treated paper, the convex segments and the concave recesses being alternately located in a direction perpendicular to the sheet transfer direction such that, when the jump wings remain in the guide position, the sheet of pre-treated paper is guided upward at both sides thereof to form a curved dropping state and is discharged to the paper receiving tray and, when the jump wings remain in the wait position, the sheet of pre-treated paper is not curved at the both sides thereof and is discharged to the paper receiving tray. 
     Other aspect and advantages of the invention will become more apparent from the following description, taken in conjunction with the accompanying drawings, illustrating by way of example the principles of the invention. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is an exploded perspective view of a preferred embodiment of a sheet discharge unit according to the present invention, wherein the sheet discharge unit is shown as being applied to a sheet discharge section of a printing machine; 
     FIG. 2 is a plan view of the preferred embodiment of the sheet discharge unit shown in FIG. 1; 
     FIG. 3 is a cross sectional view of the sheet discharge unit as viewed from its one side; 
     FIG. 4 is a cross sectional view of another part of the sheet discharge unit as viewed from its front side; 
     FIG. 5A is an enlarged, partial plan view showing a contact condition between divided wing components that are inclined in a sheet discharge direction, and a terminal end of a printed sheet; 
     FIG. 5B is an enlarged, partial plan view showing the contact condition between the divided wing components that extends in the same direction as the sheet discharge direction, and the terminal end of the printed sheet; 
     FIG. 6A is a view illustrating the contact condition between the divided wing components and a lower end of the printed sheet wherein the divided wing components have respective, upper arch shaped curved profiles; 
     FIG. 6B is a view illustrating the contact condition between the divided wing components and the lower end of the printed sheet wherein the divided wing components have respective upper flat surfaces; 
     FIG. 7 is an exploded perspective view of a second preferred embodiment of a sheet discharge unit according to the present invention, with the sheet discharge unit being shown as applied to a sheet discharge section of a printing machine; 
     FIG. 8 is a plan view of the sheet discharge unit shown in FIG. 7; 
     FIG. 9 is a cross sectional view of the sheet discharge unit of FIG. 7 as viewed from a side of the unit; 
     FIG. 10 is a cross sectional view of the sheet discharge unit of FIG. 7 as viewed from a front side; 
     FIG. 11 is a side view of a third preferred embodiment of a sheet discharge unit according to the present invention, with the sheet discharging unit being applied to the sheet discharge section of the printing machine; 
     FIG. 12 is a front view of the sheet discharge unit shown in FIG. 11; 
     FIGS. 13A to  13 C show various guide patterns of divided wing components, respectively, of the sheet discharge unit of FIG. 11; 
     FIGS. 14A and 14B show the other guide patterns of the divided wing components, respectively, of the sheet discharge unit of FIG. 11; and 
     FIG. 15 is a perspective view of a conventional sheet discharge unit. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     A description will be in detail given below of a sheet discharge unit in accordance with each of embodiments of the present invention preferably with reference to FIGS. 1 to  14 . 
     Referring now to FIGS. 1 to  4 , there is shown a first preferred embodiment of a sheet discharge unit according to the present invention which is shown as applied to a sheet discharge section of a printing machine SS. 
     In FIGS. 1 to  4 , the sheet discharge unit  1  has a transfer passage  3  formed in a traveling path of a printed sheet  2 . The transfer passage  3  is formed on a bottom plate  4  that is located in a lower area of the transfer passage  3 , and side plates  5  located at both sides of the bottom plate  4 . The bottom plate  4  has a transfer starting position and a transfer terminating position in which first and second laterally extending shafts  6  are supported in parallel to one another, respectively, with each shaft  6  carrying a pair of pulleys for rotating movement therewith. Two rows of endless belts  8 ,  8  extend in parallel to one another between the pulleys  7 ,  7 , respectively, that are located in the transfer starting position and the transfer terminating position, respectively. The two rows of the endless transfer belts  8 ,  8  are located in a central zone of the transfer passage  3 . Each of the transfer belts  8 ,  8  is caused to travel between the transfer starting position and the transfer terminating position along the transfer passage  3  by a driving force of a drive source (not shown). Also, the bottom plate  4  has a large number of suction holes  9 , and a suction fan  10  is mounted beneath the bottom plate  4 . With air above the transfer passage  3  being drawn by the suction fan  10 , the printed sheet  2  is urged toward the transfer belts  8 ,  8 . A pair of left and right sheet discharge wings  11 ,  11  are located in the transfer terminating position of the transfer passage  3  at both sides of the transfer belts  7 ,  7 . 
     Each of jump wing pairs  11  includes a plurality of laterally spaced, divided wing components  12  (with four wing components being shown in the illustrated embodiment). A lower end of each wing component  12  is fixed to each wing base member  13 , which is a part of an actuating member ACT, at a position beneath the bottom plate  4 , with left and right wing base members  13  being firmly fixed to a laterally extending wing support shaft  14  and serving as another part of the actuating member ACT. The wing support shaft  14  is not supported by the side plates  5 , and the left and right plural divided wing components  12 ,  12  are supported by the wing support shaft  14  such that the wing components  12 ,  12  are freely moveable between a guide position (indicated by a solid line in FIGS. 3 and 4) in which the wing components  12 ,  12  project upward from the bottom plate  4  as shown by a solid line in FIGS. 3 and 4 and a waiting position in which the wing components  12 ,  12  are located in a retracted position as shown by a phantom line in FIGS. 3 and 4. The bottom plate  4  has a pair of guide openings GO each composed of a plurality of laterally spaced elongated slots  15 ,  15  to allow the wing components  12 ,  12  to move between the protruding and retracted positions, with a plurality of shielding portions  16  each extending from the bottom plate  4  toward a position between adjacent elongated slots  15  to shield a spacing between the adjacent wing components  12 ,  12 . That is, each of the slots  15  is formed in the bottom plate  4  in size to have a value sufficient for allowing the protruding and retracting movement of each wing component. 
     A coil spring  17 , that forms another part of the actuating member ACT, is mounted on the wing support shaft  14  such that all of the divided wing components  12 ,  12  are urged toward the guide position. Also, one end of each of the left and right wing base members  13  has an engaging pin  18  fixed thereto, with the engaging pin  18  being held in engagement with a rod portion  19   a  of an actuating lever  19 . With such a structure, the divided wing components  12 ,  12  are moved in varying positions between the guide position and the waiting position due to upward and downward movement of the actuating lever  19 . The guide position may be defined with and selected from those positions in which all the divided wing components  12 ,  12  protrude upward from the bottom plate  4  or in which only parts of the wing components protrude upward. Due to this arrangement, it is possible to have the divided wing components  12 ,  12  to enable the printed sheet  2  of different sizes to be deformed in suitably curved profiles, respectively. 
     All the divided wing components  12 ,  12  have heights that gradually increase toward a downstream side of a sheet discharge direction T and have extreme highest distal ends sharply standing downright. As viewed in FIGS. 1 and 4, the divided wing components  12  of each set have heights that gradually increase from an inside toward an outside such that both sides of the printed sheet  2  have those curved portions which upwardly increase in heights toward right and left distal ends. As viewed in FIG. 2, each set of the right and left divided wing components  12  are arranged such that each wing component  12  extends in a direction inclined at an angle A (for example, about three degrees) with respect to the transfer direction T of the printed sheet  2 . More particularly, the right and left divided wing components  12 ,  12  are arranged to expand in outer directions toward the downstream side of the sheet discharge direction T. Also, each of the divided wing components  12  has an upwardly facing, substantially arch shaped curved surface  12   a.    
     As shown in FIG. 1, a paper receiving tray  20  is located in an area, which lies on the sheet discharging direction, at the side of a paper discharging downstream of and at a lower portion of the transfer terminating position of the transfer passage  3 . The paper receiving tray  20  has both sides mounted with side fences  21  and has a distal end, at the side of paper discharging downstream, mounted with an upright end fence (not shown). 
     In operation, when a printed sheet  2  is conducted to the transfer starting position of the transfer passage  3 , the printed sheet  2  is sucked with air drawn by the suck fan  10  toward the bottom wall of the transfer passage  3  and is urged toward the transfer belts  8 ,  8 . The printed sheet  2  that is urged toward the transfer belts  8 ,  8  is then transferred to the transfer terminating position. Here, in the event that the printed sheet  2  to be discharged has a small rigidity, the pair of sheet discharge wings  11 ,  11  each composed of the divided wing components  12  are held in the guide positions as shown by solid lines in FIGS. 3 and 4. When this occurs, the both ends of the printed sheet  2  are upwardly guided by the left and right divided wing components  12 ,  12  such that the printed sheet  2  is discharged with its both ends curved upward from a central portion. In this instance, the printed sheet  2  has an increased apparent rigidity and is caused to drop on the paper receiving tray  20  along a stable dropping trajectory. In the event that the printed sheet  2  has a strong rigidity, the left and right divided wing components  12 ,  12  are kept in their waiting positions. In this instance, the printed sheet  2  is smoothly discharged in a stable dropping state owing to its inherent property of strong rigidity. 
     During the course of the paper discharging step, when the plural divided wing components  12  are held in the guide position, the printed sheet  2  passing through the transfer passage  3  are guided by the plural divided wing components  12  located in the left and right positions. Since, in this instance, the plural divided wing components  12  are laterally spaced from one another, the printed sheet  2  is brought into contact with the plural divided wing components  12  in a minimum contact area even in a case where the left and right sheet discharging wings  11 ,  11  are formed in width that corresponds to various sizes of the printed sheet  2  and, therefore, the sheet discharging wings  11  cover or cope with printed sheets of various sizes, with a resultant decrease in running resistance of the printed sheet  2  and the amount of paper dust or paper powder produced thereby. 
     In the first preferred embodiment discussed above, when the plural divided wing components  12  are held in the wait position, although the bottom plate  4 , that serves as a bottom wall of the transfer passage  3 , has a plurality of elongated slots  15  to accommodate therein the corresponding wing components  12 , since the space between the adjacent slots  15  is sealed with the shielding portion  16  and there is no large openings left in the vicinity of the wing components  12 , the printed sheet  2  is smoothly transferred without being undesirably caught by the elongated slots  15  in the transfer passage  3 , thereby preventing the printed sheet  2  from being undesirably displaced from the paper discharging path. 
     As shown in FIG. 5A, in the first preferred embodiment, since the transfer direction T of the printed sheet  2  and the direction of each divided wing component  12  in which it extends is different from one another, the printed sheet  2  is transferred under a state in which a side edge  2   a  of the printed sheet  2  is prevented from contacting a side wall  12   b  of the divided wing component  12 , it is possible to prevent undesirable wear of the divided wing component  12  and undesirable displacement of the printed sheet  2  from its normal transfer trajectory. That is, as shown in FIG. 5B, if the transfer direction T of the printed sheet  2  and the direction of the divided wing component  12  in which it extends are identical, although the printed sheet  2  tends to be transferred with the side edge  2   a  held in contact with the side wall  12   b  of the divided wing component  12  with resultant wear of the side wall  12   b  of the divided wing component  12  and the printed sheet  2  is caused to be displaced in directions offset from the normal transfer direction T due to wear of the divided wing component  12 , it is possible to overcome these phenomena with the first preferred embodiment. 
     In the first preferred embodiment, since each of the divided wing components  12  is designed to have an upper wall formed with an arch shaped curved surface  12   a , the printed sheet  2  is softly brought into contact with the curved surface  12   a  of the divided wing component  12  and the contact surface area of the printed sheet  2  relative to the divided wing component  12  becomes minimum as shown in FIG. 6A, with a resultant decrease in the running resistance of the printed sheet  2  and the amount of paper dust or powder that would be produced from the printed sheet  2 . That is, as shown in FIG. 6B, if the divided wing components  12  have upper ends formed with flat surfaces  12   c ,  12   c , respectively, the printed sheet  2  is brought into contact with the flat surfaces  12   c ,  12   c  of the divided wing components  12  without soft touch and the contact area increases, with a resultant increase in the running resistance of the printed sheet  2  and the amount of paper powder that would be produced by the printed sheet  2  owing to the increased running resistance of the printed sheet  2 . In contrast, the first preferred embodiment makes it possible to overcome these phenomena. 
     A second preferred embodiment of a sheet discharge unit according to the present invention is illustrated in FIGS. 7 to  10 , wherein FIG. 7 is an exploded view of a sheet discharging unit mounted in a sheet discharging section of a printing machine, FIG. 8 is a plan view of the sheet discharging unit, FIG. 9 is a sectional view as viewed from a side portion of the sheet discharging unit and FIG. 10 is a cross sectional view as viewed from a front portion of the sheet discharging unit. 
     The second preferred embodiment shown in FIGS. 7 to  10  is identical to the first preferred embodiment except the pair of jump wings. Therefore, like parts bear the same reference numerals as those used in FIGS. 1 to  4  and a detailed description will be given only to the pair of jump wings. 
     Particularly, each of left and right jump wings  11 ,  11  is not a divided type but comprises a unitary type that includes laterally spaced convex segments  22 , with which the printed sheet  2  is brought into contact, and laterally spaced concave segments or recesses  23 , with which the printed sheet  2  is not brought into contact, with the convex segments  22  and the concave segments  23  being alternately formed in a direction S substantially perpendicular to the sheet discharging direction T. The bottom plate  4 , which serves as a bottom wall of the transfer passage  3 , has a pair of relatively large guide openings  24 ,  24  to allow protruding or retracting motions of the left and right jump wings  11 ,  11 , respectively. 
     Further, each of the convex segments  22  has heights that gradually increase toward a downstream side of the sheet discharging direction T and have extreme highest distal ends sharply standing downright. Also, each of the convex segments  22  of the left and right sheet discharging wings  11 ,  11  has heights that gradually increase from an inside toward an outside such that both sides of the printed sheet  2  have those curved portions which upwardly increase in heights toward right and left distal ends. In addition, each of the convex segments  22  of the left and right jump wings  11 ,  11  extends in a direction inclined at an angle A (for example, about three degrees) with respect to the sheet discharging direction T of the printed sheet  2 . More particularly, the convex segments  22  of the left and right jump wings  11 ,  11  are arranged to expand in outer directions toward the downstream side of the sheet discharging direction T. Also, each of the convex segments  22  has an upwardly facing, substantially arch shaped curved surface  22   a.    
     In the second preferred embodiment discussed above, when the left and right jump wings  11 ,  11  are held in the guide position, although the printed sheet  2  passing through the transfer passage  3  is guided by each convex segments  22  of the left and right jump wings  11 ,  11 . Since, in this instance, the convex segments  22  are laterally spaced from one another, the printed sheet  2  is brought into contact with the convex segments  22  in a minimum contact area even in a case where the left and right jump wings  11 ,  11  are formed in width that corresponds to various sizes of the printed sheet  2  and, therefore, the jump wings  11  cover or cope with printed sheets of various sizes, with a resultant decrease in running resistance of the printed sheet  2  and the amount of paper dust or powder produced thereby. 
     In the second preferred embodiment, since the transfer direction T of the printed sheet  2  and the direction of each convex segments  22  in which it extends is different from one another, the printed sheet  2  is transferred under a state in which a side edge  2   a  of the printed sheet  2  is prevented from contacting a side wall of the convex segment  22 , it is possible to prevent undesirable wear of the convex segments  22  of the jump wings  11 ,  11  and undesirable displacement of the printed sheet  2  from its normal transfer trajectory. 
     In the second preferred embodiment, since each of the convex segments  22  is designed to have an upper wall formed with an arch shaped curved surface  22   a , the printed sheet  2  is softly brought into contact with the curved surface  22   a  of the convex segments  22  and the contact area of the printed sheet  2  relative to the convex segments  22  becomes minimum, resulting in a decrease in the running resistance of the printed sheet  2  and amount of paper dust or powder that would be produced from the printed sheet  2 . 
     Namely, the second preferred embodiment substantially has the same functions and advantages as those of the first preferred embodiment discussed above. However, in the second preferred embodiment, an additional structure for preventing the printed sheet  2  from being caught by the openings  24 ,  24  is not specifically provided. 
     A third preferred embodiment of a sheet discharge unit according to the present invention is shown in FIGS. 11 to  14 , wherein FIG. 11 is a side view of the sheet discharge unit, FIG. 12 is a front view of the sheet discharge unit, FIGS. 13A,  13 B and  13 C and FIGS. 14A and 14B show various guide modes of respective divided wing components. 
     In the third preferred embodiment of FIGS. 11 to  14 , like parts bear the like reference numerals as those used in FIGS. 1 to  4  which illustrate the first preferred embodiment, and description of these like parts are omitted for the sake of simplicity and only essential structural part of the third preferred embodiment will be described. Each of the left and right jump wings  11  includes a plurality of divided wing components  25   a  to  25   d  like in the first preferred embodiment, and the divided wing components  25   a  to  25   d  are not fixed to the common base member but are fixed to individual wing base members  26  that form a part of the actuating member ACT. In addition, one end of each of the wing base members  26  is not fixed to the wing support shaft  14 , but is supported on the wing support shaft  14  for free rotation thereabout such that rotation of each of the divided wing components  25   a  to  25   b  about the wing support shaft  14  enables the individual divided wing components to move between the guide position and the wait position independently from one another. A plurality of twisted coil springs  28  are connected to the individual wing base members  26 , respectively, and, thus, each of the divided wing components  25   a  to  25   d  is urged toward the waiting position. 
     As shown in FIGS. 11 and 12, the sheet discharge unit also includes a cam shaft  30 , laterally extending at a position beneath the divided wing components  25   a  to  25   d , that carries a plurality of cam members  29  fixed to the cam shaft  30  at locations corresponding to the individual wing base members  26 , respectively. The cam members  29  and the cam shaft  30  form another part of the actuating member ACT. With such a structure, the wing base members  26  are urged toward the respective cam members  29  by the actions of the coil springs  28 . As a result, the wing base members  26  are caused to rotate around the cam shaft  30  while following the cum surfaces of the cam members  29 , respectively, to shift between the guide position and the waiting position. The plural cam members  29  have cam lobes which are shifted in angular position from one another and rotate the left and right divided wing components  25   a  to  25   d  such that they can be shifted to various guide modes composed of the highest guide position and a lower guide position shown in FIGS. 13A,  13 B and  13 C, and a wait position shown in FIGS. 14A and 14B. 
     The third preferred embodiment substantially has the same functions and advantages as those of the first preferred embodiment discussed above. Further, since the divided wing components  25   a  to  25   d  are individually and independently moveable from one another in the third preferred embodiment, the divided wing components  25   a  to  25   d  are moveable to various guide modes. Consequently, it is possible for the printed sheet  2  to be curved in a suitable profile depending on the size or the rigidity of the printed sheet  2  and, therefore, it is possible to discharge the printed sheet  2  of various kinds in a stable manner. 
     In the preferred embodiments discussed above, although the left and right divided wing components  12  and  25   a  to  25   d  and the convex segments  22  of the left and right jump wings  11 ,  11  are inclined gradually outward toward the sheet discharge direction T, the wing components and the convex segments may be inclined gradually inward to have the similar function and advantages. 
     In the preferred embodiments discussed above, although the sheet discharge unit  1  has been shown and described as applied to the sheet discharge section of the printing machine, the sheet discharge unit of the invention may also be applied to the sheet discharge section of an apparatus (a copying machine) wherein a sheet of paper is treated and discharged. 
     According to one advantage of the present invention, when the plural divided wing components remain in the guide position, a sheet of paper passing through the transfer passage is guided by the respective divided wing components located in the left and right positions. Since, in this instance, the divided wing components are separately located from one another, the contact area between the sheet of paper and all of the divided wing components becomes minimum even in a case wherein the divided wing components are located in width corresponding to various sizes of the sheet of papers, the sheet discharge unit may cover or cope with the sheet of papers of various sizes, resulting in a decrease in the running resistance of the sheet of paper and the amount of paper dust or powder that would be produced from the sheet of paper. 
     According to another advantage of the present invention, when the left and right jump wings are held in the guide position, although the printed sheet passing through the transfer passage is guided by each of the left and right sheet discharge wings, the printed sheet is brought into contact with the convex segments but is not brought into contact with the concave recesses, the contact area between the jump wings and the printed sheet becomes minimum even in a case where the sheet discharge wings are located in width corresponding to the various sizes of the printed sheet to cover or cope with the various sizes of the printed sheet, with a resultant decrease in the running resistance of the printed sheet and the amount of paper dust or paper powder that would be produced from the printed sheet. 
     According to another advantage of the present invention, when the plural divided wing components are held in the waiting position, although the bottom plate, that serves as a bottom wall of the transfer passage, has a plurality of elongated slots to accommodate therein the corresponding wing components, the space between the adjacent slots is sealed with the shielding portion and there is no large openings left in the vicinity of the wing components, the printed sheet is smoothly transferred without being undesirably caught by the elongated slots in the transfer passage, thereby preventing the printed sheet from being undesirably displaced from the paper discharging path. 
     According to another advantage of the present invention, since the transfer direction of the printed sheet and the direction of each divided wing component in which it extends is different from one another, the printed sheet is transferred under a state in which a side edge of the printed sheet is prevented from contacting a side wall of the divided wing component, it is possible to prevent undesirable wear of the divided wing component and undesirable displacement of the printed sheet from its normal transfer trajectory. According to another advantage of the present invention, since the transfer direction of the printed sheet is different from that of each convex segment of the jump wings in which it extends, the printed sheet can be transferred without the side edge being held in contact with the side wall of the convex segments and undesirable wear of the convex segments of the divided wing components is avoided and the printed sheet is caused to be displaced in directions offset from the normal transfer direction. 
     According to a further advantage of the present invention, since each of the divided wing component has an upper wall formed with an arch shaped curved surface, the printed sheet is softly brought into contact with the curved surface of the divided wing component and the contact area of the printed sheet relative to the divided wing component becomes minimum, with a resultant decrease in the running resistance of the printed sheet and the amount of paper dust or powder that would be produced from the printed sheet. 
     According to a further advantage of the present invention, since the printed sheet is brought into contact with the arch shaped curved surface of each convex segment of the jump wings and the contact area becomes minimum, with a resultant decrease in the running resistance of the printed sheet and the amount of paper dust or paper powder produced from the printed sheet. 
     According to a further advantage of the present invention, since the sheet discharge unit of the invention makes it possible to have the printed sheet to be curved in a suitable profile depending on the kinds, i.e., size or the rigidity of the printed sheet to be transferred, it is possible to discharge the printed sheet of various kinds in a stable manner. 
     According to a still further advantage of the present invention, the sheet discharge unit is applied to the sheet discharging section of the printing machine and various merits can be obtained in a manner as discussed above. 
     The entire content of a Patent Application No. TOKUGAN 2000-44898 with a filing date of Feb. 22, 2000 in Japan are hereby incorporated by reference. 
     Although the invention has been described above by reference to certain embodiments of the invention, the invention is not limited to the embodiments described above. Modifications and variations of the embodiments described above will occur to those skilled in the art, in light of the teachings. The scope of the invention is defined with reference to the following claims.