WO2009118927A1

WO2009118927A1 - Sheet processing apparatus

Info

Publication number: WO2009118927A1
Application number: PCT/JP2008/066027
Authority: WO
Inventors: Yoshihiko Naruoka; Yukio Asari; Yusuke Mitsuya
Original assignee: Kabushiki Kaisha Toshiba
Priority date: 2008-03-25
Filing date: 2008-08-29
Publication date: 2009-10-01
Also published as: JP2009227460A

Abstract

A B S T R A C T A sheet processing apparatus (10) includes a takeout mechanism (30) which rotates in contact with overlapping-direction leading ends of a plurality of postal items (P), a main conveying path (4) along which the postal item (P) taken out onto a conveying path (2) is conveyed to a succeeding processing section, a suctioning and conveying mechanism (60) which directs the postal item (P) conveyed via the conveying path (2) to a main conveying path (4) curved toward the takeout mechanism (30), and a sub-conveying path extending straight from the conveying path (2). A suctioning and conveying mechanism (60) located inside the curve of the main conveying path (4) has a suctioning and conveying belt (68) which travels curvedly while suctioning the postal item (P) being conveyed. The suctioning and conveying mechanism (60) thus directs the postal item (P) to the curved main conveying path (4). Doubly fed second and subsequent postal items (P) are conveyed straight and fed onto the sub-conveying path (6).

Description

D E S C R I P T I O N

SHEET PROCESSING APPARATUS

Technical Field

The present invention relates to a sheet processing apparatus that takes out a plurality of overlappingly loaded sheets onto a conveying path one by one to convey the taken-out sheet. Background Art

As an apparatus that processes a plurality of sheet-like articles, a sorting apparatus is known which continuously conveys a plurality of cut veneers on a conveyor and which selectively sorts and conveys any of the veneers upward (see, for example, Patent Document 1). The sorting apparatus has an endless porous conveying belt located above and adjacent to the conveyor so that the veneer selected for sorting is suctioned by the porous conveying belt and delivered to another conveyor located above.

On the other hand, as an apparatus that processes sheets such as postal items, an apparatus is known into which a plurality of overlapping sheets are loaded and in which a takeout roller contacted with a sheet corresponding to a leading end of the sheets in an overlapping direction is rotated to take out the sheets onto the conveying path one by one. In an apparatus of this kind, the takeout roller is rotated in contact with the one of the overlapping sheets corresponding to the end of the sheets. Thus, the next sheet overlapping the sheet corresponding to the end of the sheets may also be carried out. Thus, in an apparatus of this kind, a separation mechanism is provided downstream of the takeout roller to return the second and subsequent sheets carried out with the first sheet in an opposite direction (or hold the second and subsequent sheets in position) for separation.

However, a separation mechanism of this kind generates a separation torque in a direction opposite to an original conveying direction to separate the doubly fed second and subsequent sheets. Thus, unwanted stress acts on the sheets to disadvantageously contaminate or damage the sheets. Furthermore, an apparatus using a separation mechanism of this kind often processes doubly fed sheets separated from the first sheet without excluding the sheets from processing. If at least three sheets overlap, the sheets may fail to be sufficiently separated from one another and may be overlappingly conveyed.

When a plurality of as doubly fed sheets are conveyed to a downstream processing section, for example, a jam may occur in an area of a gate that switches the conveying direction of the sheets, the conveying posture of the sheets may be uncontrollably disturbed, or the overlapping sheets may be separated from one another during conveyance for any reason. As a result, the process needs to be suspended, reducing the availability of the apparatus. [Patent Document 1] Jpn. Pat. Appln. KOKAI

Publication No. 7-41226 (FIG. 1)

Disclosure of Invention

An object of the present invention is to provide a sheet processing apparatus that enables a reduction in double feed rate and an increase in apparatus availability without contaminating or damaging sheets.

To accomplish the object, a sheet processing apparatus according to the present invention comprises a loading section through which a plurality of sheets are overlappingly loaded into- the apparatus, a feeding mechanism which moves the plurality of loaded sheets in an overlapping direction to feed a first sheet located at a leading end of the sheets in the overlapping direction to a takeout position, a takeout mechanism located opposite the first sheet fed to the takeout position to rotate in a surface direction of the first sheet in contact with the first sheet to take out the first sheet onto a conveying path, a conveying mechanism which conveys the first sheet taken out onto the conveying path by the takeout mechanism, a main conveying path formed by curving the conveying path extending from the takeout position, toward a side on which the takeout mechanism is located, a negative pressure generating mechanism which exerts, from inside of the curve of the main conveying path, a predetermined negative pressure lower than an atmospheric pressure on the first sheet conveyed via the conveying path, and a sub-conveying path to which a second sheet and a subsequent sheet carried out while overlapping the first sheet guided to the main conveying path are diverged. According to the present invention, the negative pressure is exerted from the inside of the main conveying path curved toward the same side on which the takeout mechanism is located, to direct the first sheet conveyed via the conveying path, to the curved main conveying path. If double feeding occurs on the first sheet, that is, the second and subsequent sheets are carried out with the first sheet, the negative pressure generating mechanism avoids exerting a negative pressure on the second sheet overlapping a back side of the first sheet. Thus, the second and subsequent sheets advance straight under the inertial force and rigidity of the sheets and are thus separated from the first sheet and diverged to the sub-conveying path.

That is, the present invention allows doubly fed sheets to be separated from each other without the need to apply a separation torque in the direction opposite to the conveying direction of sheets as in the prior art. The present invention also prevents the second and subsequent sheets separated from the first sheet from being conveyed to the main conveying path. That is, the present invention enables the doubly fed second sheet to be reliably separated from the first sheet without applying unwanted stress to the sheets or contaminating or damaging the sheets. The present invention enables a sharp reduction in the probability of conveying the second sheet to the main conveying path and thus a reduction in the probability (double feed rate) of conveying doubly fed sheets without separating the sheets from the first sheet.

Furthermore, the present invention enables heavy or hard sheets to be diverged to the sub-conveying path. That is, the present invention can prevent heavy or hard sheets to be excluded from processing in the apparatus from being directed to the main conveying path by adjusting the curvature of the main conveying path, the magnitude of negative pressure exerted by the negative pressure generating mechanism, the conveying speed of the sheets, and the like to appropriate values. For example, if a hard sheet is taken out, a small curvature of the main conveying path or a low negative pressure of the negative pressure generating mechanism prevents the sheet from being directed to the main conveying path; the sheet is diverged to the sub- conveying path. If a heavy sheet is taken out, the inertial force is increased to move the sheet more straightly. The small curvature of the main conveying path or the low negative pressure of the negative pressure generating mechanism cause the sheet to be diverged to the sub-conveying path. In other words, the use of the apparatus according to the present invention prevents heavy or hard sheets from being taken out onto the main conveying path. This eliminates the need for a detecting device provided on the main conveying path to detect such heavy or hard sheets and an excluding and conveying path or a sorting gate which diverges such heavy or hard sheets from the main conveying path.

Brief Description of Drawings FIG. 1 is a plan view showing a sheet processing apparatus according to a first embodiment of the present invention;

FIG. 2 is a block diagram of a control system that controls the operation of the sheet processing apparatus in FIG. 1;

FIG. 3 is a partly enlarged view showing a takeout belt of a takeout mechanism incorporated in the sheet processing apparatus in FIG. 2;

FIG. 4 is a partly enlarged view showing a suctioning and conveying belt of a suctioning and conveying mechanism incorporated in the sheet processing apparatus in FIG. 2; FIG. 5 is a diagram illustrating the operation of the suctioning and conveying mechanism;

FIG. 6 is a diagram illustrating the operation of the suctioning and conveying mechanism; FIG. 7 is a flowchart illustrating the operation of the takeout mechanism;

FIG. 8 is a flowchart illustrating the operation of a trailing end suctioning mechanism;

FIG. 9 is a diagram illustrating the operation of the suctioning and conveying mechanism;

FIG. 10 is a plan view showing a sheet processing apparatus according to a second embodiment of the present invention;

FIG. 11 is a partly enlarged view of a conveying belt of a right conveying mechanism incorporated in the sheet processing apparatus in FIG. 10;

FIG. 12 is a flowchart illustrating the operation of the right conveying mechanism;

FIG. 13 is a plan view showing an essential part of a sheet processing apparatus according to a third embodiment of the present invention;

FIG. 14 is a partly enlarged perspective view of a beating wheel and a peripheral structure of the beating wheel in the sheet processing apparatus in FIG. 13; FIG. 15 is a plan view showing a variation of the sheet processing apparatus in FIG. 10;

FIG. 16 is a partly sectional view of a suctioning and conveying mechanism incorporated in a sheet processing apparatus in FIG. 15; and

FIG. 17 is a diagram illustrating the structure of a group of suction holes formed in a suctioning and conveying sleeve of the suctioning and conveying mechanism in FIG. 16.

Best Mode for Carrying Out the Invention Embodiments of the present invention will be described below in detail with reference to the drawings.

FIG. 1 is a plan view of a sheet processing apparatus 10 (hereinafter simply referred to as a processing apparatus 10) according to a first embodiment of the present invention as viewed from above. Furthermore, FIG. 2 shows a block diagram of a control system that controls the operation of the processing apparatus 10. In the description below, a plurality of postal items (sheets) of different lengths in a conveying direction are collectively processed. However, the present invention is applicable to processing of other sheets such as bills and various cards .

As shown in FIG. 1, the processing apparatus 10 has a loading section 12 through which a plurality of postal items P are overlappingly loaded at a time. An operator loads the plurality of postal items P to be processed into the loading section 12 in an overlapping upright condition. At this time, as shown in FIG. 1, the postal items P are desirably loaded so that the leading ends (upper ends in FIG. 1) of the postal items P in a takeout direction are aligned with one another. The lower ends of the postal items P loaded in the upright posture are allowed to abut against a top surface of a floor belt 14 (see FIG. 2) .

The floor belt 14, located at the bottom of the loading section 12, are allowed to travel toward one end of the postal items P in the overlapping direction by means of a motor 16 (FIG. 2) to move a lower end side of the postal items P leftward in FIG. 1. That is, a direction from a right end toward a left end of the postal items P in the overlapping direction in FIG. 1 corresponds to a feeding direction of the postal items P.

A backup plate 18 (FIG. 2) is provided at the other end, in the overlapping direction, of the postal items P loaded into the loading section 12, that is, a trailing end of the postal items P in the feeding direction; the backup plate 18 (FIG. 2) contacts a front surface of the postal item P at the other end in the overlapping direction to press the postal item P in the feeding direction. The back plate 18 is mounted in an upright condition in which the backup plate 18 is substantially parallel to the postal items P. The backup plate 18 is simply connected to the floor belt 14, described above. Thus, the backup plate 18 is moved in the overlapping direction of the postal items P in synchronism with the floor belt 14.

That is, the above-described floor belt 14 and backup plate 18 function as a supply mechanism 20 according to the present invention together with the motor 16. The plurality of postal items P loaded into the loading section 12 are moved leftward in FIG. 1 by the feeding mechanism 20. Thus, the postal item P located at the leading end in the supply direction is sequentially fed to a takeout position 22. When the postal item P at the takeout position 22 is taken out, the supply mechanism 20 is operated to feed the next postal item P to the takeout position. In this manner, the feeding mechanism 20 is operated every time the postal item P is taken out to continue feeding the postal items P to the takeout position 22 until all the loaded postal items P are fed to the takeout position 22. A takeout mechanism 30 is provided at a position where a surface of the postal item P fed to the takeout position 22 which surface is located rightward in FIG. 1. The takeout mechanism 30 has an endless takeout belt 32 traveling along the postal item P at the takeout position 22, in a surface direction

(takeout direction) (the direction of arrow T) of the postal item P. As shown in FIG. 3, the takeout belt 32 has a plurality of suction holes 32a all along the length of the takeout belt 32. The takeout belt 32 is wound and extended around a plurality of pulleys 34 including a tension pulley 34a and a driving pulley 36. The takeout belt 32 is rotated at a fixed speed by a motor 38 (FIG. 2) connected to the driving pulley 36, so as to travel in the direction of arrow in FIG. 1. Furthermore, a negative pressure chamber 31 is provided inside the takeout belt 32 and opposite the takeout position 22. An opening 33 through which a negative pressure is exerted on the postal item P at the takeout position 22 via the plurality of suction holes 32a in the takeout belt 22 is formed in an area in which the negative pressure chamber 31 lies opposite a back surface of the takeout belt 32. Furthermore, a pump 35 (FIG. 2) is connected to the negative chamber 31. An electromagnetic valve 37 is mounted in the middle of a line that connects a pump 35 and the negative pressure chamber 31 together. Thus, the takeout belt 32 is allowed to travel to open the electromagnetic valve 37 to generate a negative pressure at an opening 33 in the negative pressure chamber 31. Then, the postal item P at the takeout position 22 is suctioned to a front surface of the takeout belt 32. The takeout belt 32 travels to take out the postal item P at the takeout position 22 onto the conveying path 2. At this time, the second and subsequent postal items P (second sheet) which overlap the back surface of the first postal item P (first sheet) , which is located opposite the takeout mechanism 30, may be carried out together with the first postal item P. The condition in which a plurality of postal items P are overlappingly taken out is called "double feeding" .

Opposite sides of the conveying path 2, extending downstream of the takeout position 22 in the takeout direction, are defined by two endless conveying belts 42 and 52 wound and extended around a plurality of pulleys 41 and 51. That is, the conveying belt 42, wound around a driving pulley 46 rotated by a motor 44 (FIG. 2) in the direction of an arrow in FIG. 1, is located on the left, in FIG. 1, of the conveying path 2. The conveying belt 52, wound around a driving pulley 56 rotated by a motor 54 (FIG. 2) in the direction of an arrow in FIG. 1, is located on the right, in FIG. 1, of the conveying path 2. The conveying belt 42, the plurality of pulleys 41 and 46, around which the conveying belt 42 is wound, and the driving pulley 46 constitute a left conveying mechanism 40. The conveying belt 52, the plurality of pulleys 51 and 56, around which the conveying belt 52 is wound, and the driving pulley 56 constitute a right conveying mechanism 50. The left conveying mechanism 40 and the right conveying mechanism 50 function as a conveying mechanism according to the present invention. A suctioning and conveying mechanism 60 (negative pressure generating mechanism) is located downstream (upward in FIG. 1) of the left conveying mechanism, located on the left, in FIG. 1, of the conveying path 2, that is, on the same side on which the takeout mechanism 30 is located; the suctioning and conveying mechanism 60 directs the postal item P conveyed via the conveying path 2 toward the main conveying path 4. A trailing end suctioning mechanism 70 is provided on the right of the conveying path 2 and between the loading section 12 and the conveying belt 52 to suction a trailing end of the postal item P taken out on the conveying path 2. The trailing end suctioning mechanism 72 has a curved guide plate 72 facing the conveying path 2, a suction chamber 74 communicating with a suction port 72a in the guide plate 72, and a pump 76 (FIG. 2) that suctions the suction chamber 74. An electromagnetic valve 78 is mounted in the middle of a line joining the pump 76 and the suction chamber 74 together. The trailing end suctioning mechanism 70 exerts a negative pressure, from a side opposite to the takeout mechanism 30, on the postal item P taken out and conveyed on the conveying path 2, to brake the second and subsequent postal items P carried out while overlapping the first postal item P. The conveying path 2, extending from the takeout position, diverges in two directions. The main conveying path 4 is continuous with the conveying path 2 and extends curvedly leftward in FIG. 1. The suctioning and conveying mechanism 60 is provided inside a curve of the main conveying path 4. The sub- conveying path 6 is continuous with a downstream side of the conveying path 2 and extends substantially straight. The postal item P conveyed via the conveying path 2 at a certain speed acts to travel straight owing to the inertial force of the postal item P. That is, with no external force applied to the postal item P conveyed on the conveying path 2, almost all the postal items P are guided to the sub-conveying path 6 so as to travel straight.

The suctioning and conveying mechanism 60 is provided inside the curve of the main conveying path 4, that is, on the same side on which the takeout mechanism 30 is located. The suctioning and conveying mechanism 60 has a conveying guide 62 that is curved leftward in FIG. 1 along the main conveying path 4, curved toward the takeout mechanism 30 continuously with the conveying path 2. The conveying guide 62 has a mesh structure. A negative pressure chamber 64 is provided on a back surface of the conveying guide 62 which is spaced from the main conveying path 4. A pump 66 (FIG. 2) is connected to the negative pressure chamber 64 .

Furthermore, the suctioning and conveying mechanism 60 has an endless suctioning and conveying belt 68 that travels along a front surface of the conveying guide 62 in the conveying direction of the postal item P. As shown in FIG. 4, the suctioning and conveying belt 68b has a group of suction holes 61 formed at a predetermined pitch D along a traveling direction of the belt 68b. The group of suction holes 61 is formed of a plurality of suction holes 61a.

The length L of the group of suction holes 61 (suction area) along the traveling direction of the suctioning and conveying belt 68 is set equal to or smaller than that of one of the postal items P to be processed by the processing apparatus 10 which has the smallest length along the conveying direction (this postal item is hereinafter referred to as a the minimum postal item Pmin) . Furthermore, the pitch D of the group of suction holes 61 is set equal to or greater than the length of one of the postal items P to be processed by the processing apparatus 10 which has the greatest length along the conveying direction (this postal item is hereinafter referred to as the longest postal item Pmax) . The suctioning and conveying belt 68 is wound and extended around two pulleys 63 and a driving pulley 65. An outer peripheral surface of the suctioning and conveying belt 68, that is, a front surface of the suctioning and conveying belt 68, functions as suction surface according to the present invention which is curved along the conveying guide 62. The suctioning and conveying belt 68 is allowed to travel by using the motor 67 to rotate the driving pulley 65 in the direction of an arrow in FIG. 1.

In particular, the motor 67 rotates the suctioning and conveying belt 68 at a timing when the a conveying- direction downstream end of the group of suction holes 61 in the suctioning and conveying belt 68 aligns with the conveying-direction leading end of the postal item P conveyed via the conveying path 2. That is, the suctioning and conveying belt 68 is controlled by a control section 100 described below so as to be intermittently accelerated and decelerated in accordance with conveyance timings for the postal item P.

Thus, the suctioning and conveying belt 68 is allowed to travel, and the interior of the negative pressure chamber 64 is vacuumed by the pump 66 to place the group of suction holes 61 opposite the conveying guide 62. Then, a negative pressure is generated on the front surface of the suctioning and conveying belt 68 via the conveying guide with a mesh structure and the suction holes 61a. At this time, as described above, the suctioning and conveying belt 68 is allowed to travel in accordance with the conveyance timings for the postal item P so that the postal item P is suctioned to the front surface of the suctioning and conveying belt 68 and curved and guided to the main conveying path 4.

As described above, in the processing apparatus 10 according to the present embodiment, the plurality of postal items P are overlappingly loaded via the loading section 12 and taken out onto the conveying path 2 one by one. Thus, when significant friction occurs between the postal items P, double feeding may occur. A plurality of doubly fed postal items P reach the conveying guide 62 of the suctioning and conveying mechanism 60, for example, in a condition shown in FIG. 5. That is, in this case, of the postal items suctioned to the takeout belt 32 of the takeout mechanism 30 and taken out from the loading section 12, the first postal item Pl, which is closest to the suctioning and conveying mechanism 60, precedes the second postal item P2, which precedes the third postal item P3.

At this time, the suctioning and conveying belt 68 is controlled such that the downstream end, in the moving direction, of the group of suction holes 61 in the suctioning and conveying belt 68 overlaps the conveying-direction leading end of the first postal item Pl. Then, the conveying-direction leading end of the postal item Pl is guided in the direction of the main conveying path 4 (in the direction of arrow Tl in FIG. 1) and suctioned to the suctioning and conveying belt 68. As shown in FIG. 6, the postal item Pl is curved along the conveying guide 62 and guided to the main conveying path 4.

On the other hand, the negative pressure from the suctioning and conveying mechanism 60 does not act on the first and third postal items P2 and P3 overlapping the back surface of the first postal item Pl.

Consequently, the second and subsequent postal items P2 and P3 are separated from the first postal item Pl and conveyed toward the sub-conveying path 6 (in the direction of arrow T2 in FIG. 1) under the inertial force of the postal items P2 and P3.

A peel-off mechanism 80 is located at a diverging position between the main conveying path 4 and the sub- conveying path 6 as shown in FIG. 1. The peel-off mechanism 80 according to the present embodiment has a air nozzle 84 connected to a blower 82 (FIG. 2) . That is, the peel-off mechanism 80 functions to blow air from the downstream side of the conveying path 2 toward the diverging position via the air nozzle 84 to form a gap between the first postal item Pl directed toward the main conveying path 4 and the conveying-direction leading end of the second postal item P2. This prevents the second and subsequent postal items P2 and P3 from being directed toward the main conveying path 4 with the first postal item Pl directed toward the main conveying path 4.

As described above, according to the processing apparatus 10 configured as described above, the correctly taken-out single postal item P is guided to the main conveying path 4. The second and subsequent postal items P carried out with the first postal item P are guided to the sub-conveying path 6. Furthermore, the following postal items P are also guided to the sub-conveying path 6: postal items P that cannot be directed to the main conveying path 4 in spite of the negative pressure exerted by the suctioning and conveying mechanism 60, for example, heavy or hard postal items P.

The operation of the control section 100 of the above-described processing apparatus will be described below in detail.

Four sensors 91, 92, 93, and 94 are provided on the conveying path 2 to sense signals that trigger the operations of appropriate mechanisms. Each of the sensors 91, 92, 93, and 94 has a light emitting section and a light receiving section arranged opposite each other across the conveying path 2 to sense that an optical axis between the light emitting and receiving sections is blocked by the postal item P. The sensor thus senses the passage of the postal item P. The sensor 91, located most upstream along the conveying path 2, is placed at a position on the conveying path 2 where the optical axis passes through the conveying path 2, between the takeout position 22 and an area N in which the conveying belt 42 of the left conveying mechanism 40 and the conveying belt 52 of the right conveying mechanism 50 are overlappingly wound around the pulley 41a (this area is hereinafter referred to as a conveying nip N) . Furthermore, the sensor 92 is placed at a position where the optical axis passes through the conveying path 2 immediately after the conveying nip N along the conveying direction of the postal item P. Furthermore, the sensor 93 is placed at a position where the optical axis passes through the main conveying path 4 and the sub-conveying path 6 and which is located downstream of the position where the conveying path 2 diverges into the main conveying path 4 and the sub-conveying path 6. Moreover, the sensor 94 is placed at a position where the optical axis passes through the main conveying path 4 and which is located slightly downstream of a conveying nip 98 where the conveying belts arranged on the opposite sides of the main conveying path 4 are overlappingly wound around the pulley 96. FIG. 7 shows a flowchart illustrating the operation of the takeout mechanism 30 performed to take out the plurality of postal items P loaded via the loading section 12 onto the conveying path 2.

To start taking out the postal item P, the control section 100 first energizes the motor 38 to allow the takeout belt 32 to travel at a fixed speed. The control section 100 operates the pump 35 to vacuum the negative pressure chamber 31. In this condition, the control section 100 opens the electromagnetic valve 37 to generate a negative pressure on the front surface of the traveling takeout belt 32. The postal item P at the takeout position 22 is thus suctioned to the takeout belt 32 and thus taken out onto the conveying path 2 (FIG. 7, step 1) .

Subsequently, the control section 100 monitors an output from the sensor 92, located downstream of the conveying nip N. When the output from the sensor 92 indicates non-illumination (step 2; YES), the electromagnetic valve 37 is closed (step 3). At this time, the conveying-direction leading end of the postal item is sandwichingly held by the conveying nip N. Thus, the left and right conveying mechanisms 40 and 50 apply a conveying force to the postal item P, eliminating the need for the takeout mechanism 30 to apply a conveying force to the postal item P.

In fact, if the negative pressure is subsequently continuously exerted on the front surface of the takeout belt 32, the postal items P are unseparately taken out from the loading section 12. In other words, unless the suction force of the takeout belt 32 is eliminated at the appropriate timing after the first postal item P has been taken out onto the takeout belt 32, no gap can be formed between the first postal item P and the second postal item P.

After the electromagnetic valve 37 is closed in step 3, the control section 100 sees an output from the sensor 91, located between the takeout position 22 and the conveying nip N. When the conveying-direction trailing end of the postal item P passes through the optical axis of the sensor 91 (step 4; YES), the control section 100 allows a timer (not shown in the drawings) to start counting. A preset given time elapses (step 5; YES) after the conveying-direction trailing end of the preceding first postal item P has passed through the optical axis of the sensor 91. Then, the control section 100 opens the electromagnetic valve 37 (step 6) to start taking out the second postal item P. Thus, a gap is formed between the postal items P.

Subsequently, the control section 100 repeats the processing in steps 2 to 6, described above, until all the postal items P loaded into the processing apparatus 10 via the loading section 12 are taken out (step 7 ; NO) . The control section 100 takes out all the postal items P onto the conveying path 2 with the given gap between the postal items P. FIG. 8 shows a flowchart illustrating the operation of the above-described trailing end suctioning mechanism 70.

With the above-described takeout mechanism 30 waiting to perform a takeout operation, the control section 100 keeps the electromagnetic valve 78 of the trailing end suctioning mechanism 70 closed (FIG. 8, step 1) . When the taking-out of the postal item P is started, the control section 100 sees an output from the sensor 92, located downstream of the conveying nip N. When the conveying-direction leading end of the postal item P taken out onto the conveying path 2 blocks the optical axis of the sensor 92 (step 2; YES), the controller 100 opens the electromagnetic valve 78 (step 3) .

When the electromagnetic valve 78 is opened in step 3, the conveyance of the postal item P is not hindered even though the trailing end suctioning mechanism 70 suctions the trailing end side of the postal item P. This is because the leading end of the postal item taken out onto the conveying path 2 is sandwichingly held by the conveying nip N. Furthermore, at this timing, a negative pressure is generated via the trailing end suctioning mechanism 70. Thus, if the second and subsequent postal items P have been carried out with the first postal item P, the doubly fed postal items P can be suctioned and braked by the trailing end suctioning mechanism 70.

Subsequently, the control section iOO sees an output from the sensor 91, located between the takeout position 22 and the conveying nip N. When the trailing end of the preceding first postal item passes through the optical axis of the sensor 91 (step 4; YES), the control section 100 closes the electromagnetic valve 78 to eliminate the negative pressure (step 5) . Then, the control section 100 repeats the processing in steps 2 to 5, described above, until all the postal items P loaded into the processing apparatus 10 via the loading section 12 are taken out (step 6; NO) .

FIG. 9 shows a flowchart illustrating the operation of the above-described suctioning and conveying mechanism 60.

The control section 100 acquires a timing when the postal item P conveyed via the conveying path 2 is conveyed to the suctioning and conveying mechanism 60, on the basis of outputs from the two sensors 91 and 92, arranged upstream of the suctioning and conveying mechanism 60 in the conveying direction (FIG. 9, step 1) . The control section 100 allows the suctioning and conveying belt 68 in accordance with the conveyance timing (step 2) . At this time, as described above, the control section 100 drivingly controls the suctioning and conveying belt 68 at the timing when the downstream end of the group of suction holes 61 in the suctioning and conveying belt 68 aligns with the conveying- direction leading end of the postal item P.

Thus, the postal item P conveyed via the conveying path 2 is suctioned by the suctioning and conveying belt 68 and directed to the main conveying path 4. At this time, if any postal items P are conveyed while overlapping the postal item P directed to the main conveying path 4, the doubly fed second and subsequent postal items P move straight under the inertial force of the postal items P. The second and subsequent postal items P are separated from the first postal item P and conveyed to the sub-conveying path 6. Furthermore, at this time, the peel-off mechanism 80 blows air in between the first postal item P and the second postal item P to appropriately handle the plurality of overlapping postal items P.

If any postal item P conveyed via the conveying path is heavier than a given weight or harder than a given hardness, such a nonstandard postal item P is also conveyed to the sub-conveying path 6. Namely, the unprocessable postal items P, that is, the postal items P other than the single postal item P that can be processed by the succeeding processing section, are all conveyed to the sub-conveying path 6. The postal items P guided to the sub-conveying path 6 are collected in an excluding and collecting section (not shown in the drawings) and separately processed. After directing the postal item to the main conveying path 4, the control section 100 monitors an output from sensor 94, provided near the conveying nip 98 on the main conveying path 4, to determine whether or not the conveying-direction leading end of the postal item P has been sandwichingly held by the conveying nip 98 (step 3) . When the output from the sensor 94 indicates non-illumination (step 3; YES) , the control section 100 determines that the postal item P has been guided to the main conveying path 4 and sandwichingly held by the conveying nip 98. The control section 100 then starts a preparing operation for the next postal item P to be conveyed (step 4) . The preparing operation allows the conveying- direction leading end of the next postal item P to be conveyed to align with the downstream end of the group of suction holes 61 in the suctioning and conveying belt 68. The preparing operation includes an operation of stopping the suctioning and conveying belt at a predetermined position before the downstream end of the group of suction holes 61 reaches the conveying guide 62. However, in the processing in step 4, the suctioning and conveying belt 68 need not necessarily be stopped but needs to at least be decelerated. If the suctioning and conveying belt 68 is stopped

(or decelerated) at the above-described timing, the postal item P may have not passed through the suctioning and conveying mechanism 60 yet. However, since the conveying-direction leading end of the postal item P is sandwichingly held by the conveying nip 98, the stopped suctioning and conveying mechanism 60 is prevented from hindering the conveyance of the postal item P. Rather, when the suctioning and conveying belt 68 is stopped after the postal item P has been guided to the main conveying path 2, if another postal item P overlaps the postal item P guided to the main conveying path 2, the suctioning and conveying mechanism 60 functions to exert a negative pressure on the doubly fed postal item P to brake this postal item P.

After starting the preparing operation in step 4, the control section 100 monitors an output from the sensor 93, located near the diverging portion between the main conveying path 4 and the sub-conveying path 6, to determine whether or not the conveying-direction trailing end of the postal item P guided to the main conveying path 4 has passed through the optical axis of the sensor 93 (step 5) . Then, when the sensor output indicates illumination (step 5; YES) , the control section 100 allows the suctioning and conveying belt 68 to start traveling in accordance with the conveyance timing for the next postal item P to be conveyed (step 6) .

In this case, if only one postal item P has been conveyed to the main conveying path 4, the second postal item P is the next postal item P to be conveyed. However, if the second and subsequent postal items P overlap the postal item P conveyed to the main conveying path 4, the second and subsequent postal items P are the postal items P the trailing ends of which are detected via the sensor 93.

That is, for example, with the first postal item P conveyed to the main conveying path 4 and the second postal item separately conveyed to the sub-conveying path 6, after the sensor 93 senses the passage of the conveying-direction trailing end of the second postal item P, the suctioning and conveying belt 68 starts traveling in step 6 for the third postal item P. Then, the control section 100 repeats the processing in steps 3 to 6, described above, until no postal item P remains to be conveyed (step 7; NO) .

As described above, according to the present embodiment, the main conveying path 4 is curved toward the same side on which the takeout mechanism 30 located opposite the takeout position 22 for the overlappingly loaded postal item P lies, with the suctioning and conveying mechanism 60 located inside the curve. Thus, even if a plurality of the postal items P are conveyed in a double feeding condition, among the postal items P displaced from one another like sashimi as shown in FIG. 5, only the postal item P taken out early is guided to the main conveying path 4 as shown in FIG. 6. Consequently, the second and subsequent postal items P can be separated and fed to the sub-conveying path 6. In particular, in this case, no separation torque acting in the direction opposite to the conveying direction is applied to the doubly fed postal items P. The postal items P are thus prevented from being subjected to unwanted stress or contaminated or damaged. As a result, according to the present embodiment, the doubly fed postal items P can be reliably separated without being contaminated or damaged. This enables an increase in double feed rate and the apparatus availability.

Furthermore, the present embodiment allows nonstandard heavy or hard postal items P to be diverged to the sub-conveying path 6. For example, if a hard postal item P is taken out and when the main conveying path has a small curvature or the suctioning and conveying mechanism 60 offers a low negative pressure, the hard postal item P cannot be directed to the main conveying path 4 and is diverged to the sub-conveying path 6. If a heavy postal item P is taken out, the inertial force is increased to move the heavy postal item more straightly. Then, a small curvature of the main conveying path 4 or a low negative pressure of the suctioning and conveying mechanism 60 causes the postal item P to be diverged to the sub-conveying path 6.

In other words, the present embodiment prevents heavy or hard postal items P from being taken out onto the main conveying path 4. This eliminates the need for a detecting device provided on the downstream side of the main conveying path 4 to detect such heavy or hard postal items P and an excluding and conveying path or a sorting gate which diverges such heavy or hard postal items P from the main conveying path 4.

In the present embodiment, the length L (FIG. 4) of the group of suction holes 61 in the suctioning and conveying belt 68 along the belt traveling direction is equal to or shorter than the shortest postal item Pmin. Furthermore, the suctioning and conveying belt 68 is allowed to travel so as to align the downstream end of the group of suction holes 61 with the conveying- direction leading end of the postal item P. This prevents the single group of suction holes 61 from disadvantageously suctioning the plurality of postal items P at a time. Furthermore, in the present embodiment, the pitch D of the group of suction holes 61 (FIG. 4) is equal to or greater than the length of the longest postal item Pmax. Thus, even if the postal items P overlap each other, only one of the postal items P is suctioned to the suctioning and conveying belt 68, and the overlapping other postal item P is diverged to the sub-conveying path 6.

Now, a second embodiment of the present invention will be described. As shown in FIG. 10, a sheet processing apparatus 110 (hereinafter referred to as a processing apparatus 110) according the second embodiment is different from the first embodiment in the structure of a right conveying mechanism 50' located on the right side, in FIG. 10, of the conveying path 2, extending from the takeout position 22. The remaining part of the -structure is substantially the same as that in the above-described first embodiment. Components of the second embodiment which function similarly to corresponding ones of the first embodiment are denoted by the same reference numerals and will not be described in detail.

As shown in FIG. 11, a conveying belt 112 of the right conveying mechanism 50' has a plurality of suction holes 112a over the length of the belt 112. Furthermore, the right conveying mechanism 50' has a negative pressure chamber 114 positioned inside the conveying belt 112 opposite the above-described suctioning and conveying mechanism 60 across the area in which the conveying path 2 connects to the sub- conveying path 6. The negative pressure chamber 114 is mounted such that an opening 114a of the negative pressure chamber 114 lies opposite a back surface of the conveying belt 112. A pump (not shown in the drawings) is connected to the negative pressure chamber 114. An electromagnetic valve 116 is mounted in the middle of a line connecting the negative pressure chamber 114 and the pump together. The conveying belt 112, the negative pressure chamber 114, the pump, and the electromagnetic valve 116 function as a peel-off mechanism and a leading end suctioning mechanism according to the present invention.

FIG. 12 is a flowchart illustrating the operation of the above-described right conveying mechanism 50'. The control section 100 monitors the output from the sensor 93, located near the position where the sub- conveying path 6 diverges from the main conveying path 4, to wait for the leading end of the postal item P to arrive. When the conveying-direction leading end of the postal item P blocks the optical axis of the sensor 93 (FIG. 12, step 1; YES), the control section 100 calculates the length of the postal item P passing through the optical axis of the sensor 93 in the conveying direction, on the basis of the conveying speed of the postal item P and the time for which the sensor output continues to indicate non-illumination.

Upon determining that the length of the postal item P is greater than that of the longest postal item Pmax, the control section 100 determines that the postal item P has been doubly fed (step 2; YES) . The control section 100 thus opens the electromagnetic valve 116 (step 3). Thus, the conveying-direction leading ends of the second and subsequent postal items P conveyed while overlapping the above-described postal item P like sashimi are sequentially suctioned to the conveying belt 112 of the right conveying mechanism 50' and thus separated from the postal item P being conveyed to the main conveying path 4.

After opening the electromagnetic valve 116 in step 3, the control section 100 closes the electromagnetic valve 116 at the appropriate timing so as to prevent the next postal item P to be conveyed from being suctioned to the conveying belt 112 of the right conveying mechanism 50'. That is, at this time, the control section 100 monitors the output from the sensor 93, and when the sensor output indicates illumination (step 4; YES), uses this as a trigger to close the electromagnetic valve 116 (step 5) . Then, the control section 100 repeats the processing in steps 1 to 5 until no postal item P remains to be conveyed (step 6; NO) .

As described above, the present embodiment can exert effects similar to those of the above-described first embodiment but also allows the second and subsequent postal items P overlapping the first postal item P to be suctioned to the conveying belt 112 of the right conveying mechanism 50'. Consequently, the conveying-direction leading ends of the second and subsequent postal items P can be more reliably directed toward the sub-conveying path 6. Thus, the doubly fed postal items P can be more reliably separated.

Now, a third embodiment of the present invention will be described.

FIG. 13 shows a plan view of an essential part of a sheet processing apparatus 120 (hereinafter simply- referred to as a processing apparatus 120) according to a third embodiment. The processing apparatus 120 has substantially the same structure as that of the processing apparatus according to the above-described embodiment except that a beating wheel 122 is provided near the diverging portion between the main conveying path 4 and the sub-conveying path 6. Thus, here, components of the processing apparatus 120 which function similarly to corresponding ones of the above- described processing apparatus 110 are denoted by the same reference numerals and will not be described in detail. The beating wheel 122 is located between the main conveying path 4 curved leftward in FIG. 13 and the sub-conveying path 6 and always rotates counterclockwise in FIG. 13. The beating wheel 122 functions as a peel-off mechanism according to the present invention.

FIG. 14 shows a partly enlarged perspective view of the beating wheel 122 and the peripheral structure of the beating wheel 122. The beating wheel 122 has a rotator 124 that rotates counterclockwise (in the direction of arrow R in FIG. 14) and a plurality of beating blades 126 extending radially from an outer peripheral surface of the rotator 124. Rotating the beating wheel 122 counterclockwise allows the conveying-direction leading ends of the second and subsequent postal items P being conveyed to the main conveying path 4 while overlapping the first postal item P to be beaten so as to be directed toward the sub-conveying path 6. The second and subsequent postal items P can thus be separated from the first postal item P.

As described above, the present embodiment can exert effects similar to those of the above-described first and second embodiments but also allows the doubly- fed second and subsequent postal items P to be forcibly separated by beating the postal items P with the beating wheel 126. The doubly fed postal items P can thus be reliably separated.

Furthermore, the beating wheel 122 not only- functions to separate the doubly fed postal items P but also acts effectively on the postal item P directed to the main conveying path 4. That is, if the postal item P being conveyed toward the main conveying path 4 while being suctioned to the suctioning and conveying belt 68 peels off the suctioning and conveying belt 68, the conveying-direction leading end of the postal item P is beaten so as to be directed toward the sub-conveying path 6. Consequently, the postal item P that is likely to cause a jam can be excluded from processing and fed to the sub-conveying path 6.

Now, a variation 130 of the processing apparatus according to the above-described second embodiment will be described. FIG. 15 shows a plan view of a processing apparatus 130 with the structure of the suctioning and conveying mechanism changed. FIG. 16 shows a sectional view of an essential part of a changed suctioning and conveying mechanism 140. The processing apparatus 130 has substantially the same structure as that of the processing apparatus 110 according to the above-described second embodiment except for the provision of the suctioning and conveying mechanism 140 with the different structure. Thus, components of the processing apparatus 130 which function similarly to corresponding ones of the above- described processing apparatus 110 are denoted by the same reference numerals and will not be described in detail. The suctioning and conveying mechanism 140 comprises a substantially cylindrical shaft 144 having an internal negative pressure chamber 142, and a substantially cylindrical suctioning and conveying sleeve 148 having a group of suction holes 146 composed of a plurality of suction holes 146a. The suctioning and conveying sleeve 148 is coaxially attached to a rotating shaft 154 of a motor 152. The motor 152 is fixed to a motor base 162. On the other hand, the shaft 144 is fixed to a roller base 164 using a flange plate 158 and a screw 159. The shaft 144 is fixed to the roller base 164 in a posture in which an opening 142a of the negative pressure chamber 142 formed inside the shaft 144 is located opposite the main conveying path 4.

As shown in FIG. 17, the length L of the group of suction hole 146 in the suctioning and conveying sleeve 148 along the rotating direction is set equal to or smaller than the minimum postal item Pmin. The pitch of the group of suction holes 146 is set equal to or greater than the length of the longest postal item Pmax. In the present variation, the single group of suction holes 146 is provided along the rotating direction of the suctioning and conveying sleeve 148. Thus, the outer peripheral length of the suctioning and conveying sleeve 148 is set equal to or greater than the length of the longest postal item Pmax. If the suctioning and conveying mechanism 140 with the roller structure as described above is adopted, the curvature of the main conveying path 4 depends on the outer diameter of the suctioning and conveying sleeve 148. That is, the outer diameter of the suctioning and conveying sleeve 148 needs to be appropriately selected in order to set the curvature of the main conveying path 4 to a desired value. Thus, to set a relatively large outer diameter to increase the radius of curvature, two or more groups of suction holes 146 may be provided along the rotating direction of the suctioning and conveying sleeve 148. At any rate, the above-described suctioning and conveying mechanism 140 functions similarly to the suctioning and conveying mechanism 60 according to the first and second embodiments. That is, the control section 100 acquires the conveyance timing for the postal item P to be conveyed via the conveying path 2 to drivingly control the motor 152 such that the suctioning and conveying sleeve 148 is rotated at the timing when the conveying-direction trailing end of the postal item P aligns with the downstream end of the group of suction holes 146 in the suctioning and conveying group 148 in the conveying direction. A suction pump (not shown in the drawings) is connected to the negative pressure chamber 142 inside the shaft 144 so as to always generate a negative pressure via the opening 142a in the negative pressure chamber 142. As described above, the processing apparatus 130 according to the present variation can exert effects similar to those of the processing apparatus 110 according to the above-described second embodiment but also allows the doubly fed postal items P to be reliably separated without being subjected to unwanted stress. This enables a reduction in double feed rate. The present invention is not limited to the as described embodiments. In implementation, the components of the embodiments can be varied without departing from the spirit of the present invention. Furthermore, various inventions can be formed by appropriately combining a plurality of the components disclosed in the above-described embodiments. For example, some of the components illustrated in the above-described embodiments may be deleted. Moreover, components of the different embodiments may be appropriately combined together.

For example, in the above-described embodiments, the postal items P are processed as sheets. However, the present invention is not limited to this aspect. The present invention is also applicable to an apparatus that processes other sheets such as bills or various cards.

Industrial Applicability

The sheet processing apparatus according to the present invention has the above-described configuration and effects and thus enables a reduction in double feed rate and an increase in apparatus availability without contaminating or damaging sheets.

Claims

C L A I M S

1. A sheet processing apparatus characterized by comprising: a loading section through which a plurality of sheets are overlappingly loaded into the apparatus; a feeding mechanism which moves the plurality of loaded sheets in an overlapping direction to feed a first sheet located at a leading end of the sheets in the overlapping direction to a takeout position; a takeout mechanism located opposite the first sheet fed to the takeout position to rotate in a surface direction of the first sheet in contact with the first sheet to take out the first sheet onto a conveying path; a conveying mechanism which conveys the first sheet taken out onto the conveying path by the takeout mechanism; a main conveying path formed by curving the conveying path extending from the takeout position, toward a side on which the takeout mechanism is located; a negative pressure generating mechanism which exerts, from inside of the curve of the main conveying path, a predetermined negative pressure lower than an atmospheric pressure on the first sheet conveyed via the conveying path; and a sub-conveying path to which a second sheet and a subsequent sheet carried out while overlapping the first sheet guided to the main conveying path are diverged.

2. The sheet processing apparatus according to claim 1, characterized in that the sub-conveying path is diverged from the main conveying path by extending the conveying path substantially straight.

3. The sheet processing apparatus according to claim 1, characterized in that the negative pressure generating mechanism has a curved suction surface which moves along a conveying direction of the sheet inside the curve of the main conveying path and allows the suction surface to generate a negative pressure to suction the sheet to guide the sheet to the main conveying path.

4. The sheet processing apparatus according to claim 3, characterized n that the suction surface includes at least one suction area in which a negative pressure is applied to the sheet to suction the sheet, length of the suction area along a moving direction of the suction surface is equal to or smaller than that of a shortest sheet which is one of the sheets processed by the sheet processing apparatus which has a smallest length along the conveying direction, and a pitch of the suction area along the moving direction is equal to or greater than length of a longest sheet which is one of the sheets to be processed by the sheet processing apparatus which has a greatest length along the conveying direction.

5. The sheet processing apparatus according to claim 4, characterized by further comprising a control section which moves the suction surface at a timing when a conveying-direction leading end of the sheet conveyed via the conveying path aligns with a downstream end of the suction area in the moving direction.

6. The sheet processing apparatus according to claim 1, characterized by further comprising a peel-off mechanism provided at a diverging position between the main conveying path and the sub-conveying path to peel off a conveying-direction leading end of the second sheet carried out with the first sheet directed to the main conveying path, from the first sheet to direct the leading end of the second sheet to the sub-conveying path.

7. The sheet processing apparatus according to claim 6, characterized in that the peel-off mechanism has an air nozzle which blows air from a downstream side of the conveying path toward the diverging position.

8. The sheet processing apparatus according to claim 6, characterized in that the peel-off mechanism has a beating wheel which beats the conveying-direction leading end of the second sheet so as to direct the conveying-direction leading end of the second sheet toward the sub-conveying path.

9. The sheet processing apparatus according to claim 6, characterized in that the peel-off mechanism has a leading end suctioning mechanism provided opposite the negative pressure generating mechanism across an area in which the conveying path joins the sub-conveying path to suction the conveying-direction leading end of the second sheet so that the conveying- direction leading end of the second sheet leaves the first sheet.

10. The sheet processing apparatus according to claim 1, characterized in that the conveying mechanism has a nip at which the conveying-direction leading end of the first sheet taken out from the takeout position is received and at which a conveying force is applied to the first sheet, and the apparatus further comprises a trailing end suctioning mechanism provided between the takeout position and the nip and opposite the takeout mechanism across the conveying path to, after the conveying- direction leading end of the first sheet is received at the nip, exert a negative pressure on the second sheet so as to suction the second sheet in a direction in which the second sheet leaves the first sheet.