Device for stacking and aligning individually supplied sheets

Abstract: At the free end of an arm (1) which is pivotable about a shaft (12), a driven coupling portion (3) with a claw coupling (3a) is rotatably mounted, said coupling being held in positive engagement with a sleeve (5) shiftable on a shaft (2). Sleeve (5) is provided with a circumferential cam groove (5b) which has an advancing and returning pitch and is engaged by a stationary projection (11). Sleeve (5) is provided with a concentrical collar (5d) on which a second wheel (4) having a smooth circumferential surface is shiftably mounted and held in positive engagement. On an eccentrical collar (5a) of sleeve (5), a first wheel (6) designed as a radial ball bearing is mounted whose circumferential surface has high static friction. When sleeve (5) is set in motion it moves to and fro, the second wheel (4) being urged via an inclined surface (4b, 4c) into contact with the first wheel (6) and entraining said wheel by frictional engagement. The cam groove (5b) and the eccentrical mounting of the first wheel (6) are adapted to each other such that the first wheel (6) is driven in a pulse-type manner by frictional engagement and acts in a pulse-type manner on the sheet to be aligned.

Description: The invention relates to a device with a collecting tray for aligning sheets which are individually supplied to said collecting tray in which they are stacked one above the other, in particular copy sheets produced by a copier, where said collecting tray comprises a support surface and a lateral limiting wall arranged parallely with the direction of entrance of the sheets as well as an abutment associated with the front end side of the sheets, said device including a drivable wheel which is arranged at the free end of a pivotable arm and rests on the incoming sheet and which aligns said sheet both at the lateral limiting wall and at the front abutment. Such a device is known from DE-C-31 07 768. It is known (DE-31 07 768-C2) for individually supplied sheets to be aligned, with respect to a front abutment and a lateral limiting wall of a collecting tray, by means of a roller positioned obliquely to the direction of sheet transport. It is also known (US-PS 4 718 657) for the surface of the sheet stack to be sensed and kept at a predetermined level by means of a rotatable and pivotable aligning roller which serves to stack the sheets in a staggered arrangement. In both of these known devices the aligning roller constantly subjects the uppermost sheet to always the same pressure force, whereby in particular thin sheets of only slight inherent stiffness may become compressed so that the plane position of the sheets deposited cannot be ensured. In particular if sheets collected in stacks are to be further processed, for example stapled in sets, the sheets must be sufficiently plane to allow them to be properly stapled. It is the object of the invention to design an aligning device of the generic type such that the incoming sheets can be stacked rapidly and reliably and free from tension, that the sheets can be stacked free from tension and that moreover the sheet stack is maintained at a level which allows the collected sheets to be further processed. According to the invention this object is attained in that drivable wheels of identical diameter are arranged at the free end of an arm on a common shaft, of which the first wheel is eccentrically mounted and the second wheel is concentrically mounted, the first wheel is mounted for rotation on an eccentrical collar of a rotatably mounted sleeve, said collar being disposed eccentrically with respect to shaft, the second wheel is shiftably mounted on a concentrical collar of the rotary sleeve, said collar being disposed concentrically with respect to shaft, sleeve together with the first and the second wheel are shiftable on shaft, the second wheel is held in positive engagement with sleeve, sleeve is permanently held in positive engagement with a rotatably mounted and drivable coupling portion, and the first wheel, together with the second wheel and the sleeve, when resting on the incoming sheet, is shiftable towards the lateral limiting wall and, when separated from said sheet, is shiftable in the opposite direction. According to the invention this object is advantageously attained in that a light barrier or a switch is arranged in the path of pivotal movement of said arm, said light barrier or switch respectively interrupting the further transport of sheets towards the collecting tray when a predetermined height of the sheet stack has been reached. According to an advantageous modification of the invention the circumferential surface of the sleeve is provided with a circumferential cam groove held in engagement with a stationary projection and having in its shifting direction an advancing and returning pitch so that the sleeve when made to rotate carries out a reciprocating movement together with the first and the second wheel. The device according to the invention advantageously allows incoming sheets to be transported and aligned by a pulse-type temporary engagement so that tension built up by compression can be relieved in the non-transport intervals and the sheets can be stacked in a plane position. In a particularly advantageous manner the pulse-type engagement of the sheets is brought about by a wheel supported on a ball bearing, which is periodically driven such that it is entrained by frictional engagement in its lifted position. When placed on the incoming sheet, however, it transports said sheet solely by its own momentum. The advantage is that the sheet is only engaged and aligned by the entraining momentum of the wheel thus caused so that it is not unnecessarily compressed when it reaches its aligned position. Further features and advantages can be inferred from the description of embodiments of the invention illustrated in the drawing and from the sub-claims. The drawing shows schematically in Fig. 1 a partially sectional plan view of the device; Fig. 2 a lateral view of the device according to Fig. 1; Fig. 3 a partial enlarged view of the device according to Fig. 1; Fig. 4 a partial enlarged view of an embodiment of the device according to Fig. 1, and Fig. 5 a partial sectional view, along line A-A, of the device according to Fig. 4. The device for aligning sheets according to the invention is arranged in a finisher unit of a known type not illustrated in which individually supplied sheets, in particular sheets produced by a copier, are combined in sets in a collecting tray 20 and stapled using a stapling device 17. Of the finisher unit, which is connected with a copier not illustrated, only those parts are shown as are necessary to understand the invention. Sheets are supplied in the direction of the arrow "A" to a collecting tray 20 which is inclined in the direction of movement of the sheets and in which the sheets are deposited on a sheet stack 21. During the supply operation the individual sheets are moved into the range of action of an aligning device to be described further below which places the sheets into contact with a front abutment 19 and a lateral limiting wall 18. The sheets are aligned in the range of action of a stapling device 17 of a type known per se and not illustrated whose position is indicated in dash-dotted lines. Above the collecting tray 20, an arm 1 is pivotally mounted about a shaft 12 by means of ball bearings 15, 16 which are positively and frictionally held on U-shaped webs 1d, 1e of arm 1 by snap connections. Between the webs 1d, 1e, a first driving wheel 13 mounted for rotary movement is driven by a first traction means 14 and engaged by a second traction means 22. The second traction means 22 drives a second driving wheel 9 rigidly connected with a coupling portion 3 and connected to a shaft 2 which is mounted on the free end of arm 1. Shaft 2 is also mounted by means of ball bearings 7 and 8 which are held in positive and frictional engagement on outriggers 1a, 1b of arm 1 by means of snap connections. Coupling portion 3 is provided with grooves 3a which are positively engaged by claws 5e of a sleeve 5. Sleeve 5 is shiftable on shaft 2 and comprises on its circumferential surface a circumferential cam groove 5b with a pitch advancing and returning in the shifting direction. A projection 11 which is stationarily mounted on arm 1 engages cam groove 5b. Sleeve 5 has a concentrical collar 5d and an eccentrical collar 5e directly adjacent thereto. A second wheel 4 is shiftably mounted on the concentrical collar 5d and has diametrically arranged indentations 4a which are engaged by diametrically arranged entrainment members 5c which are mounted on sleeve 5. The entrainment members 5c which are provided with rounded crests engage inclined surfaces 4b of the indentations 4a, said surfaces being arranged in the path of movement of the entrainment members 5c. The outer circumference of the second wheel 4 is provided with a smooth surface (low friction coefficient). A first wheel 6 in the form of a radial ball bearing is disposed on the eccentrical collar 5a of sleeve 5. The inner ring of said bearing is firmly seated on collar 5a and, at the outer circumference of its outer ring, is provided with a layer having high static friction (high friction coefficient). The wheels 4 and 6 have the same diameter. A lug 1c associated with a light barrier 10 is molded to arm 1. The front abutment 19 of the collecting tray 20 is mounted for pivotal movement about a journal 19a and movable in the direction of the arrow "D" by an electromagnet not illustrated. The device functions as follows: Under the action of the weight of the components arranged on arm 1, the wheel 4 and 6 respectively rests on the bottom of the collecting tray 20 and on sheets accumulated on said bottom respectively. Coupling portion 3 set in rotary motion by the traction means 14 and 22 entrains sleeve 5 and the second wheel 4 positively engaged with that sleeve by rotation in the direction of the arrow "E". The rotating sleeve 5 slides with its circumferential cam groove 5b along stationary projection 11 and during such movement is once moved to and fro along shaft 2 during each revolution. During one revolution of sleeve 5 the first and the second wheel 6 and 4 respectively is alternately moved into engagement with the sheet such that during the first half of the revolution of sleeve 5 only wheel 4 rests on the sheet while the first wheel 6 is separated from said sheet due to its eccentricity. During the second half of the revolution however only the first wheel 6 rests on the sheet and, as a result of its eccentricity, separates the second wheel 4 from the sheet. With respect to the pitch of the circumferential cam groove 5b, the eccentrical collar 5a of sleeve 5 is arranged such that when sleeve 5 is moved by the pitch of cam groove 5b in the direction of the arrow "F" the second wheel 4 rests on the uppermost sheet and the first wheel 6 is lifted off said sheet. Since the second wheel 4 rests on the uppermost sheet relative torsion occurs between said wheel and the rotating sleeve 5. As a result, the entrainment members 5c move against the inclined surfaces 4b of the second wheel 4, urge said wheel into contact with the outer ring of the first wheel 6 and entrain said wheel by frictional engagement while rotating in the direction of the arrow "E". When the first wheel 6 has been set in motion it comes to rest on a sheet entering the collecting tray 20 in the direction of the arrow "A" during the second half of a revolution of sleeve 5, during which a shifting movement occurs in the direction of the arrow "C", and moves said sheet in the direction of the arrow "B" (see Fig. 1) both towards the front abutment 19 and the lateral limiting wall 18. Since the second wheel 4 is separated from the sheet during the engagement of the sheet with the first wheel 6 the relative torsion of the second wheel 4 is no longer effective so that the frictional engagement with the first wheel 6 is interrupted. Hence the first wheel 6 only influences the sheet to be aligned by the entraining momentum of its weight thus released so that the sheet when reaching its end position at the front abutment 19 and the lateral limiting wall 18 respectively is not further advanced unnecessarily and compression is avoided. When the first wheel 6 has rotated so far that due to its eccentric mounting its effective surface retreats behind the outer circumference of the second wheel 4, the device rests with the smooth surface of the second wheel 4 on the uppermost sheet. Sleeve 5 slides back in the direction of the arrow "F" until it reaches the point of reversal of cam groove 5b and subsequently starts another shifting movement in the direction of the arrow "C" during which the first wheel 6 is set in motion and then carries out its transport function as was described before. Depending on the distance over which the sheets to be aligned have already automatically passed under the action of gravity when they arrive in the direction of the arrow "A", they are more or less frequently subjected to pulse-type transport movements until they have reached their final position. During its pulse-type transport movements each sheet is only transported by small distances of for example 4 to 5 mm so that it is not compressed when reaching its final position. The first wheel 6 is only brought into engagement with the sheet in the manner described when sleeve 5 is moved by the rising cam section of cam groove 5b in the direction of the arrow "C". In this way the sheet to be aligned is engaged in a pulse-type manner and transported in the direction of the arrow "B" but is again and again released between the transport phases in that the first wheel 6 is lifted so that tension that might lead to compression can be relieved. Moreover, as was described before, during the transport phase the alignment of the sheets only depends on the entraining momentum of the weight of the first wheel 6 released. Since moreover the area of engagement of the first wheel 6 with the sheet is located adjacent to the sheet edges to be aligned, the sheet is very resistent to kinking. All these steps result in that the sheets are reliably and rapidly aligned and that in particular tension building up during alignment and leading to compression can be relieved in the phases in which the first wheel 6 is separated from the sheets so that the sheets can be stacked in a plane position and with their edges precisely aligned. The sheets reliably stacked and aligned in this manner can subsequently be stapled by a stapling device 17 to form an aligned set. When the front abutment 19 is opened in the direction of the arrow "D" the stapled sheet stack 21 can be transferred to a depositing device connected to the unit and not illustrated. In order that the accumulated sheet stack 21 should not exceed the stack height that can be handled by the stapling device 17 without disturbances a device is provided for limiting the height of the sheet stack. That device comprises a stationary fork-type light barrier 10 which is adapted to receive a lug 1c molded to arm 1 of the aligning device. As soon as the stack height has been reached that can be maximally handled by the stapling device, lug 1c covers the light barrier 10, which interrupts the further transport of sheets. Since lug 1c is an integral part of arm 1 the stack height can be measured in an advantageous manner by the aligning device resting under the action of gravity on the sheet stack 21 while the sheet stack 21 is compressed, and thus under conditions essential for determining whether a sheet stack 21 has been stapled in a functionally proper manner. In contrast to the embodiment described the stack height can also be measured by means of a switch 23 arranged in the path of movement of arm 1 and indicated in dash-dotted lines in Fig. 2. A further embodiment to be described with reference to Figs. 4 and 5 is directed at improving the frictional engagement between the first and the second wheel 6 and 4 respectively. It differs from the embodiment according to Figs. 1 to 3 in that the projection 11 and the second wheel 4 are differently designed. The projection 11 according to Fig. 4 is mounted in arm 1 for rotation about its longitudinal axis and is biased by a spring not illustrated for rotary movement in the direction of the arrow "E" (see Fig. 5). The portion of projection 11 which engages the cam groove 5b is provided with flattened walls 11a, 11b held in frictional engagement with the walls of cam groove 5b. The second wheel 4 of this embodiment is provided with indentations 4a as well (see Fig. 4) which, via entrainment members 5c, allow a positive engagement with sleeve 5 and a shifting movement in the direction of the arrow "C". The shifting movement is brought about by an inclined surface 4c provided on the second wheel 4, said surface extending into the path of movement of projection 11 and engaging, rather than the cam groove 5b provided in that area, projection 11 and its face 11a respectively. The inclined surface 4c which forms an arcuate segment enclosing sleeve 5 is adapted to the shape of cam groove 5b. The functioning of the device according to Figs. 4 and 5 differs from that of the first embodiment as follows: As soon as projection 11 reaches the inclined surface 4c while sleeve 5 is rotating, the torque applied to projection 11 by its spring is transmitted to the second wheel 4 and urges said wheel into frictional engagement with the first wheel 6. As a result of this frictional engagement the first wheel 6 is entrained and set in rotary motion, the frictional engagement terminating when the projection leaves the inclined surface 4c so that the first wheel 6 is exclusively driven by the motion imparted by the entrainment and thus acts on the sheet to be aligned. Owing to the spring-biased torque of projection 11, its faces 11a, 11b permanently rest against the walls of cam groove 5b. The inclined surface 4c is thus reliably urged aside so that the frictional engagement between the second and the first wheel 4 and 6 respectively occurs under constant conditions. In contrast to the embodiment according to Figs. 1 and 2 shaft 2 can also be driven in that the driving motor is arranged at the free end of arm 1 (not illustrated) and directly drives shaft 2. A drive designed in this manner helps to avoid vibrations or movement caused by the traction means so that smooth operation of the aligning device is achieved.

Claims: Device with a collecting tray (20) for aligning sheets which are individually supplied to said collecting tray in which they are stacked one above the other, in particular copy sheets produced by a copier, where said collecting tray comprises a support surface and a lateral limiting wall (18) arranged parallely with the direction of entrance of the sheets as well as an abutment (19) associated with the front end side of the sheets, said device including a drivable wheel means (4, 6) which is arranged at the free end of a pivotable arm (1) and rests on the incoming sheet and which aligns said sheet both at said lateral limiting wall and at said front abutment, characterized in that said drivable wheel means comprises drivable wheels (4,6), said drivable wheels (4, 6) of identical diameter are arranged at the free end of an arm (1) on a common shaft (2), of which the first wheel (6) is eccentrically mounted and the second wheel (4) is concentrically mounted, the first wheel (6) is mounted for rotation on an eccentrical collar (5a) of a rotatably mounted sleeve (5), said collar being disposed eccentrically with respect to shaft (2), the second wheel (4) is shiftably mounted on a concentrical collar (5d) of the rotary sleeve (5), said collar being disposed concentrically with respect to shaft (2), sleeve (5) together with the first and the second wheel (6 and 4 respectively) are shiftable on shaft (2), the second wheel (4) is held in positive engagement with sleeve (5), sleeve (5) is permanently held in positive engagement with a rotatably mounted and drivable coupling portion (3), and the first wheel (6), together with the second wheel (4) and the sleeve (5), when resting on the incoming sheet, is shiftable towards the lateral limiting wall (18) and, when separated from said sheet, is shiftable in the opposite direction. Device according to claim 1, characterized in that a light barrier (10) or a switch (23) is arranged in the path of pivotal movement of said arm (1), said light barrier or switch respectively interrupting the further transport of sheets towards the collecting tray (20) when a predetermined height of the sheet stack (21) has been reached. Device according to claim 1 or 2, characterized in that the sleeve (5) comprises a circumferential cam groove (5b) arranged on its circumferential surface and having an advancing and returning pitch in the direction of shifting and in that a projection (11) stationarily arranged on arm (1) engages cam groove (5b). Device according to claim 1, 2 or 3, characterized in that the first and the second wheel (6 and 4 respectively) are arranged directly adjacent to each other, the first wheel (6) is mounted closest to the lateral limiting wall (18), the second wheel (4) is arranged between the first wheel (6) and the sleeve (5), the second wheel (4) comprises on its side facing away from the first wheel (6) an inclined surface (4b, 4c) which is periodically brought into engagement with an entrainment member (5c) of sleeve (5) and the stationary projection (11) respectively, the second wheel (4) can be axially shifted and urged into contact with the first wheel (6) by frictional engagement when engaged with the entrainment member or projection and the first wheel (6) is entrained by frictional engagement when it is in its lifted position. Device according to one or several of claims 1 to 4, characterized in that the circumferential surface of the first wheel (6) has a high coefficient of friction and the circumferential surface of the second wheel (4) has a low coefficient of friction. Device according to one or several of claims 1 to 5, characterized in that the first wheel (6) is designed as a radial ball bearing whose inner ring is frictionally connected with the eccentrical collar (5a) of sleeve (5) and whose outer ring is drivable by frictional engagement and has a layer of high static friction. Device according to one or several of claims 1 to 6, characterized in that arm (1) comprises at its free end outriggers (1a, 1b) in a fork-shaped arrangement for rotatably mounting shaft (2) and in that the aligning means (3, 4, 5, 6, 11) are arranged between the outriggers (1a, 1b). Device according to one or several of claims 1 to 7, characterized in that the coupling portion (3) is driven by a traction gear (9, 13, 14, 22) whose power take-off occurs at a shaft (12) serving as a journal (12) for arm (1). Device according to one or several of claims 1 to 7, characterized in that the coupling portion (3) is drivable by an electric motor directly engaging shaft (2).

Inventors: HESS WERNER, HESS, WERNER, Hess, Werner, c/o KODAK AKTIENGESELLSCHAFT
Applicants: EASTMAN KODAK CO, KODAK AG, EASTMAN KODAK COMPANY, KODAK AKTIENGESELLSCHAFT
Application year: 1992
Main classification: B65H29
IPC codes: B65H31, B65H29