Method of and apparatus for collating sheets

Abstract

 in an apparatus for and method of collating sheets, sheets are conveyed to a stacking platform 154 in alternate offset fashion by grippers 84 and 86 (not shown). After the first group of sheets has been stacked, the platform is raised above a reciprocable arm 250 which is then swung into a position to support a non-overlapped portion of the bottom sheet and the platform lowered. The grippers then convey the second group of sheets to the platform 154 where they are inserted below correspondingly offset sheets of the first group, the arm 250 being reciprocated between sheets to allow a previously stacked sheet supported thereon to drop. Thus the non-overlapped portions of adjacent sheets are supported sequentially and the second group of sheets collated with the first group. The method is repeated until all the sheets comprising a set have been inserted into all the sets. The stack of offset sets is then ready for removal from the apparatus by an operator.

Description

[0001] This invention relates to a method of and apparatus for collating sheets, which are received serially in groups of similar sheets.

[0002] In prior art collators, all the first sheets of a multi-sheet document are produced and transported serially to the collator and there inserted.one sheet at a time into different physically discrete bins. Then, all the second sheets of the document are produced and transported serially to the collator and there inserted into the bins, each of which already contains a first sheet. This process is repeated until a complete set has been built up in each of the bins.

[0003] The size of collators is directly dependent on the number of discrete bins and the physical dimensions thereof. Generally, the number of discrete bins determines the maximum number of sets that can be run in a particular job. The physical dimensions of each discrete bin determine the maximum sheet size that can be processed and the maximum number of sheets per discrete bin.

[0004] Since there is usually an overall physical size limitation, prior art collators have been designed to strike a balance between the maximum number of sets that can be run in a job and the maximum number of sheets that can comprise a set. Thus, in order to meet the physical size requirement, typical prior art machines have a capacity of 20 sets comprising 100 sheets each, giving a total sheet capacity of 2,000. Such a machine suffers from the disadvantage that a job of more than 20 sets or of sets comprising more than 100 sheets each cannot be run, even though the total of sheets is less than the sheet capacity of 2,000, for example 30 sets of 20 sheets each, or lO sets of 150 sheets each.

[0005] There is also a built-in operator inconvenience and cost in unloading these collators. For example, for a 20 bin collator which is loaded to capacity,'20 separate hand motions are required by an operator to unload, and for those collators not having automatic stapling, the operator will have to take care not to mix the sets by either stapling each set as it is removed, or by stacking the sets offset from one another to clearly demarcate them. ,

[0006] Now, according to one aspect of the present invention, a method of collating sets of sheets, which are received serially in groups of similar sheets, comprises the steps of stacking the sheets of the first group received in individually offset fashion, demarcating each first sheet from adjacent first sheets, and inserting individual sheets of the next group in the same offset fashion contiguous to individual first sheets, and thereafter inserting, if necessary, individual sheets of subsequent groups in the same contiguous to individual prior-inserted sheets of the same set to form collated sets of sheets.

[0007] According to another aspect of the invention, apparatus for collating sets of sheets, which are received serially in groups of similar sheets, comprises means to stack the sheets of the first group received in individually offset fashion, demarcating each first sheet from adjacent first sheets, and means to insert individual sheets of the next group in the same offset fashion contiguous to individual.first sheets and to insert, if necessary, individual sheets of subsequent groups in the same offset fashion contiguous to individual prior inserted sheets of the same set to form collated sets of sheets.

[0008] The invention thus provides job flexibility in that within the total sheet capacity of the collator jobs are not limited to a maximum number of sets or to a maximum number of sheets in a set.

[0009] In addition, the collated sets of a job may be removed from the collator in one operator action, the sets being clearly demarcated from each other.

[0010] The claimed invention may be carried out in the ways described in detail below with reference to the accompanying drawings, in which:

FIG. 1 is a perspective view of the apparatus according to the invention;

FIG. 2 is an enlarged perspective view of part of the apparatus of Fig.l;

FIG. 3 is a side elevation of the apparatus of Fig.l;

FIG. 4 is a section on the lines IV-IV of Fig.3;

FIG. 5 is an enlarged perspective view from below of another part apparatus of Fig.l;

FIG. 6 is an enlarged side view of yet a further part of the apparatus of Fig.l;

FIGS. 7 and 8 are plan views of other parts of the apparatus of Fig.l in different positions of operation;

FIGS. 9 to 14 illustrate the method of collating according to the invention;

FIG. 15 is a circuit diagram of an embodiment of control logic for the apparatus of Fig.l; and

FIG. 16 is a timing diagram illusyiting the

[0011] 

The sheet entry scation 18 includes lower and upper sheet guides 24 and 2f between which is a path for incoming sheets. A pair of low friction rollers 28 and 30 is fixed to a drive roller shaft 32 which is journaled in upset tabs 34 and 36 integral with the guide 26. The shaft 32 is operatively coupled to a mctor (not shown) to rotate the rollers 28 and 30 to feed a sheet 14 between the guides 24 and 26 to the arcuate sheet transport station 20. Mounted on the top surface of upper sheet guide 26 adjacent the station 20 is a lever actuated sheet path switch 38, whose actuator lever is in the sheet path and engageable by a sheet to detect the presence or absence of a sheet at the sheet transport station 20. Also mvunted on the top surface of the guide 26 to one side of the sheet path are first and second lever actuated sheet gripper position switches 40 and 42. The switch 40 has two pairs of contacts, one normally closed, the othe normally open. The switch 42 has a normally closed par of contacts.

[0012] The arcuate sheet transport station 20 includes four pairs of gripper belt pulley 44 and 46, 48 and 50, 52 and 54, and 56 and 58. The pairs of pulleys are fixed to pulley shafts 60, 62, 64 and 66, respectively. The pulley shafts are journaled in a main support frame 68 and grooved peripherally to be engaged by teeth on the inner surfaces of two gripper transporting timing belts 70 and 72 which encircle and engage pulleys 44, 48, 52 and 56, and 46, 50, 54 and 58, respectively. A drive shaft pulley 74 is fixed to the shaft 66 externally of the frame 68. A gripper drive motor timlng belt 76 encircles and couples the drive shaft pulley 74 and a gripper drive motor pulley 80 fixed to shaft 82 of a gripper drive motor 78. The sheet path lies between tie belts 70 and 72.

[0013] First and second sheet grippers 84 and 86 are disposed across the sheet path with their ends connected to the belts 70 and 72 so that the sheet grippers move with the belts. The grippers are equally spaced on the belts, so that when one grippe is adjacent the sheet entry station 18, the other is at the entrance to the sheet receiving station 22. Mounted on he frame 68 adjacent the sheet receiving station 22 is a levee actuated sheet sensor switch 282, whose actuator lever is in the sheet path and engageable by a sheet to detet the presence or absence of a sheet. The switch 282 has two pairs of normally open contacts.

[0014] The first seet gripper 84 includes a first sheet gripper bar 88 which is bent to form four V-shaped integral corrugations 92, 4, 96 and 98. The gripper bar 88 is disposed perpendicular to the belts 70 and 72 and includes three integral shet gripper arms 104, l06 and 108. The arms extend forwardy from the bar 88 at right angles thereto and are of diffeent lengths. The arm 104, nearest the belt 72 is short and the arm lO8 nearest the belt 70 is long, so that the end. of the arms lie on a line disposed at an angle to the bar 88. Fixed to the ends of the arms are sheet gripper clips 110, 112 and 114, respectively. On the end of the gripper bar 88 attached to the belt 70 is mounted a switch actuator comprising an elevated contour 100 for engagement by the lever of the sheet gripper position switch 40, and a recessed contour 102 for engagement by the lever of the sheet gripper position switch 42.

[0015] The second sheet gripper 86 includes a second sheet gripper bar 90 which is bent to form four V-shaped integral corrugations 116, 118, 120 and 122, aligned with the corrugations in the bar 88. Attached to the end of the bar 90 on the belt 70 is mounted a switch actuator comprising an elevated contour 124 for engagement by the lever of the sheet gripper position switch 42, and a recessed contour 126 for engagement by the lever of the sheet gripper position switch 40. The gripper bar 90 is disposed perpendicular to the belts 70 and 72 and includes three integral sheet gripper arms 128, 130 and 132. The arms extend forwardly from the bar 90 at right angles thereto and are of different lengths. The arm 128, nearest the belt 70, is short and the arm 132, nearest the belt 72, is long, so that the ends of the arms lie on a line disposed at an angle to the bar 90, equal and opposite to the angle between the bar 88 and the line joining the ends of the arms 104, 106 and 108. Fixed to the ends of the arms 128, 130 and 132 are sheet gripper clips 134, 136 and 138, respectively. The arms 128, 130 and 132 are not aligned with the arms 108, l06 and 104, but are slightly offset therefrom. The levers of the switches 38 and 282 are aligned with corrugations 94 and 118, so that the bars 84 and 86 do not operate the switches.

[0016] An entry cam plate 140 is fixed to the frame 68 across and below the path of the gripper bars and has three first sheet gripper entry cams 142, 144 and 146 (Fig.2) upset from its surface to engage and open simultaneously the first sheet gripper clips 110, 112 and 114 respectively, in order to grip a sheet to be processed. The plate 140 also has three second sheet gripper entry cams 148, 150 and 152 upset from its surface to engage and cam open simultaneously the second sheet gripper clips 134, 136 and 138, respectively. To ensure simultaneously, the cams 142, 144 and 146 lie on a line parallel to line joining the ends of the arms 104, l06 and 108 (Fig.l) and the cams 148, 150 and 152 lie on a line parallel to.the line joining the ends of the arms 128, 130 and 132.

[0017] With the first sheet gripper 84 (Fig.2) in position adjacent the sheet entry station 18, the clips 110, 112 and 114 are held open by the cams 142, 144 and 146, respectively. The levers of the switches 40 and 42 rest on the actuator contours 100 and 102, respectively. As the sheet 14 is driven forward by low friction rollers 28 and 30, the lever of the sheet path switch 38 is engaged and lifted and the operation of the switches 38, 40 and 42 is signalled to the system control logic. The leading edge of the sheet 14 contacts the first sheet gripper clip 110 and is stopped thereby. Due to the low friction drive of the rollers 28 and 30, forward drive by the roller 28 ceases while forward drive is continued by the roller 30. Accordingly, the sheet 14 is skewed and offset until the leading edge is driven into and contacts the first sheet gripper clip 112, as shown in dotted lines. The gripper 84 then moves forward, the rollers 28 and 30 driving the sheet 14 to keep the leading edge in the clips 110 and 112, until the clips 110, l12 and l14 disengage from the cams 142, 144 and 146 and close firmly gripping the sheet 14. As illustrated, the sheet 14 is of a standard size, e.g. A4, and engages the clips 110 and 112 with its longer side. Larger size paper may be used e.g., 21.59 cm x 35.56 cm (8.5 in. x 14 in.), in which case the sheet will be additionally gripped by first sheet gripper clip 114.

[0018] When the gripper 80 is in position adjacent the sheet entry station 18, the clips 134, 136 and 138 are held open by the cams 148, 150 and 152, respectively. The levers of the switches 40 and 42 rest on the actuator contours 126 and 124, respectively. As a sheet is driven forward by rollers 28 and 30, it will first engage and lift the lever of the switch 38. Thereafter its leading edge will engage the clip 136 or 138, according to the size of the sheet being driven. The roller 30 will begin to slip on the surface of the sheet and the sheet will be skewed or offset by continued drive of the roller 28, until the clip 134 is engaged. The skew or offset is in the opposite direction to that given to a sheet engaging the clips on the gripper 84. Thereafter the gripper 86 moves forward and the rollers 28 and 30 drive the sheet forward to keep the leading edge in the clips, until they are disengaged from the cams 148, 150 and 152 and close to grip the sheet firmly.

[0019] The unitary bin sheet receiving station 22 includes a movable sheet platform 154 (Figs. 3 and 4) which has integral therewith four sheet platform support pulley blocks 156, 158, 160 and 162, arranged two on each side of the platform, with pulleys 164, 166, 168, and 170 respectively, rotatably mounted therein. The top of the frame 68 on one side is cut away at 172 and 174 to reveive rotatably mounted sheet platform lift pulleys 176 and 178. A sheet . platform support cable 180 has an end secured to the bottom of one side of the frame 68 and passes over sheet platform support pulley 164 and under sheet platform support pulley 164, with the other end of the cable secured to the other side of the frame 68 between the top and bottom. Another sheet platform support cable 182 has an end secured to the bottom of the one side of the frame 68 and passes over pulley 170 and under pulley 168, with the other end of the cable secured to the other side of the frame 68 between the top and bottom. Thus, the platform 154 is capable of being raised or lowered while maintaining a balanced position relative to the frame.

[0020] The raising or lowering of movable sheet platform 154 is effected by a pair of sheet platform lift cables 184 and 186 whose one ends are secured to the pulley blocks 156 and 162, respectively. The cables pass over sheet platform lift pulleys 176 and 178, respectively, and have their other ends wound around and secured to a sheet platform lift shaft 188, rotatably mounted in spaced supports 190 and 192 secured to the frame 68. The shaft 188 extends beyond the frame 68 and carries a toothed pulley 202. A sheet platform lift motor 194 is mounted on the frame 68 and has a shaft 200 carrying a toothed pulley 198. A timing belt 196 is entrained around and couples the pulleys 198 and 202. Rotation of the motor 194 rotates the shaft 188 to wind up or out the cables 184 and 186 to raise or lower the platform 154.

[0021] The platform 154 also has an arcuate cutout 212 (Fig. 6) in its edge closest to the shaft 60. The edge of the platform 154 remote from the shaft 60 has a shape related to the angular offset of sheets delivered by the grippers 84 and 86 and has upstanding triangular sheet restraining tabs 204, 206, 208, and 210, for restraining the forward motion of sheets delivered to the stack. The corrugations on the bars 88 and 90 are such as to allow the bars to pass over the platform 154 and tabs.

[0022] Beyond the platform 154 in the direction of sheet movement is a stationary sheet stack constrainer wall 214 (Figs. 1, 4 and 5), secured to the frame 68. The wall 214 is configured in the same manner as the adjacent edge of the platform 154, so that the platform can rise and fall alongside the wall. The'lower face of the wall 214 has triangular cutout portions 216, 218, 220 and 222 aligned with the tabs 204, 206, 208 and 210, respectively so that the bars 88 and 90 can pass between the platform 154 and wall 214 in the position shown in Fig.4. The wall 214 is connected to a shaped plate 224 (Fig.5) which is corrugated to match the cutout portions 216, 218, 220 and 222 and has three first sheet gripper exit cams 228, 230 and 232 and three second sheet gripper exit cams 234, 236 and 238. The cams on the plate 224 are aligned with the cams on the plate 140. The sheet gripper exit cams are situated so that the first sheet gripper clips 110, 112, and 114 on the gripper 84 are cammed open simultaneously by the first sheet gripper exit cam thereby releasing a sheet onto the sheet platform 154, the tabs 204 and 208 restraining forward motion of the sheet. Similarly, the second sheet gripper clips 134, 136, and 138 of the gripper 86 are cammed open simultaneously by the second sheet gripper exit cams thereby releasing a sheet onto the-.sheet platform 154, the tabs 206 and 210 restraining forward motion of this sheet.

[0023] It will be appreciated that the shape of wall 214 and the adjacent edge of the platform 154 is determined by the size of sheet to be stacked and the amount of offset given by the clips on the gripper bars. If larger size sheets are to be handled, the wall 214 must be given an enlarged configuration on one side as shown in broken lines in Figures 1 and 5. In such case, the cam 236 must be retractable, when not required for small sheets, and the corresponding gripper clip 136 rendered inactive for larger sheets by retraction of the cam 150.

[0024] The interaction between a cam and a clip is illustrated in Fig.6. The forward edge of a sheet 14 of paper.is against a tongue 111 upset from the resilient material of the clip. The forward portion of the sheet is gripped between the clip and a chamfered edge of the arm 104. Engagement of the clip 110 with the cam 228 springs the clip away from the arm 104, releasing the paper just before it strikes the tab 204 on the platform 154.

[0025] A light source 238 is disposed on and seared to one side of the frame 68, and provides a narrow light beam directed upon a sensor 2400 on the other side of the frame 68. Also mounted on the other side of the frame 68 are lever actuated switches 242 and 244 which sense the sheet platform in upper and lower limit positions, respectively.

[0026] A sheet separator mechanism 246 (Fig.l) is disposed above the sheet path upon a mounting bar 248 fixed to the sides of the frame 68. Pivoted to the bar 248 is one upstanding end of a sheet separator and support arm 250. On the other horizontal end thereof is a rotatably mounted friction reducing roller 252. Being freely rotatable, the roller 252 reduces the drag friction on sheets being separated and supported during collation. Fixed to the one end of the arm 250 is a lever arm 254 (Fig.7) with an elongated slot.

[0027] A reciprocating position solenoid 256 is carried by a bracket 258 slidably mounted on the bar 248 by screws 260 and 262 in slots in the bracket. The solenoid 256 has a plunger 264 with a link 266 engaged in the slot in the lever arm 254. A spring 272 acts on the lever arm 254 to extend the plunger 264. Energisation of the solenoid 256 causes the arm 250 to be pivoted from a first position A to a second position B within the arcuate cutout 212 of the platform 154.

[0028] A home position solenoid 268 is secured to the bar 248 and has a plunger 270 attached to the slidable bracket 258. With both solenoids 256 and 268 energised, the arm 250 is pivoted to a third or home position C.

[0029] With both solenoids 256 and 268 de-energised, the return spring 272 causes the arm 250 to pivot to the first position A.

[0030] Prior to a stacking or collation operation, the platform 154 is located in a position below the line of the beam from the light source 238 to the light sensor 240. In this position (Fig.4), there is room for the gripper bars 88 and 90 to pass between the wall 214 and the platform 154 and to release the sheets they carry to fall onto the platform in offset fashion, that is with odd sheets in one position and even sheets in another position. A large part of the sheets overlap, but there are portions of the odd sheets which do not overlap the even sheets, and vice versa. The roller 252 on the arm 250 in position A is aligned with the non-overlapping portions of the odd sheets and in position B with the non-overlapping portions of the even sheets. In position C, the roller 252 and arm 250 are clear of all sheets. If the height of the stack sheets on the platform 154 causes the beam between the source 238 and sensor 240,to be obscured, the platform 154 is lowered to allow further sheets to be stacked thereon.

[0031] The following description assumes that nine sets, each of twentyfive sheets, need to be collated, giving a total number of sheets of two hundred and twenty five.

[0032] Nine copies of sheet 1 are supplied in succession and delivered by the grippers 84 and 86 in alternate offset positions (Fig.9).

[0033] The arm 250 pivots between positions A and B, but does not affect the stack on the platform 154 which is below the beam between source 238 and sensor 240. Alternate insertion of sheets onto the platform 154 by grippers 84 and 86 continues until the last sheet of the first sequence, that is sheet 1 of set 9, is inserted onto the platform 154 by first sheet gripper 84 (Fig.9). The sheets are stacked alternately in offset fashion, the offset clearly demarcating each first sheet from adjacent first sheets.

[0034] The arm 250 is then pivoted to position C and the platform 154 raised until it is above the top of the roller 252. The arm 250 is pivoted to position A, so that it is beneath the sheets on the platform 154. The platform 154 is lowered and the non-overlapped portions of the odd sheets of the stack are supported by the roller 252 of the arm 250 (Fig. 10). The platform 154 is lowered until the light beam is no longer obstructed, leaving space for the insertion of sheet 2 of set 1 by the first sheet gripper 84. The corner of sheet 1 of set 1 rests directly on the roller 252 of arm 250. The gripper 84 inserts sheet 2 of set 1 below sheet 1 of set 1, deposits the new sheet in alignment with the previous sheet and passes out from between the platform 154 and the wall 214.

[0035] The arm 250 (Fig.ll) is pivoted to position B, thereby dropping sheet 1 of set 1 onto sheet 2 of set 1. The roller 252 of the arm 250 now supports the non-overlapped portions of the even sheets on the platform 154, so that the corner of sheet 1 of set 2 rests directly on the roller 252 of arm 250. Sheet 2 of set 2 is inserted by second sheet gripper 86 below and deposited upon sheet 1 of set 2. After insertion, deposition and passage of the gripper 86 beyond the wall 214, the arm 250 is pivoted to position A, thereby dropping sheet 1 of set 2 onto sheet 2 of set 2.

[0036] The stack of offset sheets is now supported by the non-overlapped portions of the odd sheets resting on the roller 252 of arm 250. Sheet 2 of set 3 is now inserted and deposited, followed by pivotation of the arm 250, to drop sheet 1 of set 3 and to prepare the stack for sheet 2 of set 4.

[0037] This action is repeated as will be understood, until sheet 2 of the last set, set 9 has been inserted and deposited. The arm 250 is pivoted to position B to release sheet 1 of set 9 and then to position C to allow the platform 154 to be raised again to its upper position above the roller 252 of arm 250. The arm 250 is pivoted to position A and the platform 154 lowered to rest the corner of sheet 2 of set 1 upon the roller 252 of arm 250. The gripper 84 then inserts and deposits sheet 3 of set 1 below sheet 2 of set l. The arm 250 is pivoted to position B to release sheets 2 and 1 of set 1 to lie on top of sheet 3 of set 1- on the platform 154. The stack is thus prepared for the insertion and deposition of sheet 3 of set 2 by gripper 86.

[0038] This action continues until all sets consist of three sheets. The platform 154 is raised and lowered as before, with the arm 250 being pivoted to positions C and A as before and the stack is ready to receive the fourth sheets of the sets.

[0039] Each time the platform 154 is lowered, it descends until the light beam between the source 238 and sensor 240 is not obstructed. This leaves room for about twenty five sheets to be deposited on the platform before the light beam is obscured.

[0040] When, during this operation, about twentyfive sheets have been deposited on the platform 154, the light beam between source 240 and sensor 238 is obstructed. This causes the platform 154 to be lowered, until the light beam is no longer obstructed, allowing another twentyfive sheets to be stacked.

[0041] When each of sets 1 to 7 has been completed with twenty- five sheets, the arm 250 (Fig.12) is moved to position B supporting the corner of set 8, which is not complete. Sheet 25 of set 8 is inserted and deposited by second sheet gripper 86, thereby completing set 8. At this stage in the operation, the platform 154 is lowered each time a new sheet is inserted, because each set dropped by the movement of the arm 250 after insertion of a new sheet consists of twenty-five sheets.

[0042] Figure 13 shows the final sheet 25 of set 9 being inserted by first sheet gripper 84. The arm 250 is in position A supporting the corner of set 9, which is not completed. After insertion and deposition of the sheet, and removal of the gripper, the arm 250 is pivoted to position B, thereby dropping the sheets of set 9 onto sheet 25 of set 9 on the platform 154.

[0043] All nine sets are now completed and the arm 250 is pivoted to position C (Fig.14), to allow the platform 154 to be raised to its upper position, making it convenient for an operator to remove the collated stacked sets.

[0044] It will be appreciated that the number of sets and number of sheets in each set is given only by way of example and may be varied withen practical limitations of weight and height of stack and space available above and below the insertion level.

[0045] In the example given, the front side of each sheet is . uppermost, so that subsequent sheets of a set must be inserted below existing sheets. If the front side of each sheet were to face downwards, then subsequent sheets of a set would have to be inserted above existing sheets, necessitating movement of the arm 250 to the other of positions A and B than that described.

[0046] Offsetting alternate sheets by angular skewing is not the only method available for carrying the invention into effect. Non-overlapping portions must be provided by which the stack of overlapping offset sets of sheets may be alternately engaged and disengaged, allowing division of the stack to permit additional sheet insertion.

[0047] An electro-mechanical logic control is provided to allow the functions of the apparatus to be more or less mechanically automated, but it will be understood that, more sophisticated logic control, for example, a microprocessor control may be used.

[0048] One example of such a logic control is illustrated in Figure 8. In this control, there is an electro-mechanical counter 276, which can be set manually or automatically to the number of sets to be collated, and counted down as each sheet arrives so that it is at zero upon completion. The counter 276 is then reset, either manually or automatically, to the number of sets for the next sheets to arrive, and this is repeated until all the sheets of all the sets have arrived.

[0049] The counter 276 controls switches (not shown) which connect a platform homing signal line 274 to earth line 273 only when at zero.

[0050] If the.apparatus is to be used in association with a copier, duplicator, printer or like machine, the earth connection signals may be taken from the associated machine, because such machines usually have incorporated therein a continuous counter which is operated electromechanically on each copy cycle.

[0051] There are five relay coils Rl, R2, R3, R4 and R5 and two relay hold coils H3 and H4. Relay coil Rl, when energised, closes normally open contacts Rl-l, Rl-3 and Rl-4 and opens normally closed contacts Rl-2 and Rl-5. Relay coil R2, when energised, closes normally open contacts R2-1 and opens normally closed contacts R2-2. Relay R3, when energised.and when held by energisation of hold coil H3, opens normally closed contacts R3-1, R3-2 and closes normally open contacts R3-3 and R3-4. Relay R4, when energised and when held by energisation of hold coil H4, closes normally open contacts R4-1 and R4-2. Relay R5, when energised, closes normally open contacts R5-l.

[0052] With the counter 276 at zero, at the end of an operation or before the beginning of another, the earth potential on line 273 is connected to line 274 through the normally closed contacts R3-1 to one side of relay Rl, whose, other side is connected to a power supply line 277. Comtacts Rl-3 and Rl-4 are closed and energise the solenords 256 and 268, respectively, thus holding the arm 250 in position C. Contacts Rl-2 are opened, preventing energisation of relay R-2. Contacts Rl-l are closed, energising relay R5 whilst the contacts of sheet platform upper limit switch 242 remain closed. Energisation of relay R5 closes contacts R5-l, thereby energising sheet platform reversible lift motor 194 to raise the platform 154 until in the upper position the limit switch 242 is actuated to open its contacts. When this occurs, relay R5 is de-energised, the contacts R5-1 open and the motor 194 is de-energised, causing the platform 154 to come to rest in the upper position. When the number of sets to be stacked is entered in the counter 276, manually or automatically, earth potential is removed from line 274. Relay Rl becomes de-energised, the contacts Rl-3 and Rl-4 open, allowing the arm 250 to return to position A. Contacts Rl-l open to maintain de-energisation of relay R5. Contacts Rl-2 close. The'platform 154 in the upper position obstructs the light beam from source 238 to sensor 240. The source 238 and sensor 240 form part of a sensor unit 278 connected to earth line 273 and power supply line 277 and including a signal amplifier. With the light beam obstructed, the sensor unit 278 provides an earth potential to sheet height sensor output line 280 which is connected through normally closed contacts R3-2, the contacts of sheet platform lower limit switch 244 and contacts Rl-2, to relay R2. Energisation of relay R2 causes contacts R2-1 to close and motor 194 to be energised to lower the platform 154 until the light beam is unobstructed. The earth potential on line 280 increases to the supply voltage thus de-enerc Lng relay R2, opening contacts R2-1 to de-energise motor 19 The momentum of the system causes the platform 154 to come to rest below the light beam leaving room for about twenty- five sheets before obstruction occurs.

[0053] The gripper 84 is in position to receive a sheet, so that the normally open contacts of switch 40 are closed and the normally closed contacts open by contour 100. When a sheet actuates the switch 38, relay R3 is energised.

[0054] Contacts R3-1 and R3-2 are opened, disabling relays Rl and R2. Contacts R3-3 and R3-4 are closed. Closure of contacts R3-3 does not energise the hold coil H3 because the normally closed contacts of switch 40 are open. When the switch 38 is closed, a signal is sent over line 275 to the counter 276 to cause a count-down to the next lower number. If first sheet gripper 84 is in the position to receive a sheet, the normally open contacts of switch 40 are closed by counter 100. Relay R4 is not energised because both sets of contacts of switch 282 are open as the gripper 86 at the entrance to station 22 does not hold a sheet.

[0055] The contacts R3-4 close upon energisation of relay R3, energising gripper drive motor 78 to advance the first sheet gripper 84 towards the station 22 and the second sheet gripper 86 to advance through the station 22 and to a position to receive the next sheet. Shortly after the start of such advance, the lever of the switch 40 disengages the contour 100, so energising the holding coil H3 through the contacts R3-3 and de-energising the relay R4, which is however latched by its holding coil H4. The gripper 84 advances a sheet towards the station 22 and its presence there is sensed by closure of the switch 282. As the gripper 86 reaches the position to receive the next sheet, the switch 42 is operated by the contour 124. This opens the normally closed contacts and de-energises the holding coil H3 and thus releases relay R3. This de-energises the motor 78, bringing the grippers 84 and 86 to rest.

[0056] The next sheet arrives and operates the switch 38, energising the relay R3 and thus the motor 78 grippers 84 and 86 are advanced and the switch 42 is released from contour 124. The relay R3'is then latched on by holding coil H3 and the gripper 84 draws the first sheet into the station 22 where it is released on to the platform 154, with the arm 250 in position A (though not in this case performing its later function). Gripper advance continues until the gripper 84 reaches the position to receive a sheet, where the switch 40 is operated by contour 100. Opening of the normally closed contacts of switch 40 de-energises the holding coil H3 to release the relay R3, because closure of one pair of contacts of the switch 282 at this time has no effect since line 274 is not at earth potential. The relay R4 is energised through the closure of the other pair of contacts of switch 232 and the normally open contacts of switch 40 and is held on by holding coil H4 through normally closed contacts of switch 42. This energises solenoid 256, which moves the arm 250 to position B.

[0057] The arrival of a third sheet to operate switch 38 restarts this double cycle which is repeated as further sheets arrive, until the sheet for the last set arrives. At this point, the counter 276 is counted down to zero and earth potential applied to line 274. However, energisation of relay R3 and consequential opening of contacts R3-1 prevents energisation of relay Rl. If the number of sets is an odd number, e.g. nine, the gripper 84 receives the last sheet and the switch 40 is operated by the contour 100. This causes the solenoid 256 to pivot the arm 250 to position B. Energisation of relay R3 causes the grippers 84 and 86 to be advanced and the relay R3 is latched on when the lever of the switch 40 disengages the contour 100. The grippers continue to advance through the apparatus until the gripper 84 reaches the position to enter the station 22. At this point the gripper 86 is in position to receive another sheet and the switch 42 is operated by contour 124. However, the holding coil H3 continues to be energised through the closed contacts of switch 282 which connect it to the line 274 at earth potential. The gripper 84 continues through the station 22 until it reaches the position to receive sheets and the switch 40 is operated by contour 100. At this point, the holding coil H3 is de-energised, because the switch 282 has re-opened due to the absence of a sheet in gripper 86. Relay R3 is de-energised and the apparatus stops with the gripper 84 -in position for the second sheet of the first set.

[0058] If the number of sets is an even number, the last sheet will be conveyed by gripper 86. When the switch 38 is operated by the sheet, the switch 42 is open due to contour 124. However, holding coil H3 will be energised through switch 282 which is operated by the previous sheet. When the gripper 86 arrives in front of the station 22, the switch 282 is again operated by a sheet and the holding coil H3 continues to be energised through switch 282 until the lever of the switch 40 disengages the contour 100, and energisation is then through the normally closed contacts of switches 40 and 42. When the gripper 86 reaches the position to receive a sheet the switch 42 opens, but a connection from the line 274 to between the switches 40 and 42 enables continued energisation of the holding coil _H3 until the gripper 84 reaches that position. The normally closed contacts of switch 40 are opened and the holding coil H3 de-energised, releasing relay R3.

[0059] The relay Rl is energised through the normally closed contacts R3-1 from the line 274. The relays R2 and R3 are disabled by opening of contacts Rl-2 and Rl-5. The solenoids 256 and 268 are energised by closure of contacts Rl-3 and Rl-4. The relay R5 is energised by closure of contacts R1-1. This closes the contacts R5-1 which energise the motor 194 to raise the platform 154 to the upper position, carrying the stack of first sheets of the sets in alternate offset configuration. On reaching the upper position, the switch 242 is opened, the relay R5 de-energised.

[0060] When the second sheets of the sets are to be delivered, the number of sets to be stacked is entered in the counter 276, manually or automatically, and earth potential removed from the line 274.

[0061] The operation then commences and continues as above described, the first function being the lowering of the platform 154 with the arm 250 in position A. The stack of sheets is thus left in position for the second sheet of the first set to be inserted. The arm 250 cannot be moved from this position until a sheet is at the entrance to station 22, as sensed by switch 282, and the gripper 84 is in position to receive a sheet as sensed by operation of switch 40 by contour 100.

[0062] With the second sheet of the second set to be inserted, the arm 250 is moved to position B, allowing the first sheet of the first set to drop on to the second sheet of the first set on the platform 154. Offset collation continues until all the second sheets are in the stack and the platform and stack are returned to the upper position with the arm 250 in position C.

[0063] The operation as before described is then repeated as many times as necessary until all sheets of all sets are collated. As sheets are stacked on the platform 154, the light beam from source 238 to sensor 240 may be obstructed causing the sensor unit 278 to earth the line 280. At this point, the relay R3 is held by holding coil H3 or energised through switch 38. Thus the relay R2 cannot be energised, because the contacts R3-2 are open. When a sheet has passed the switch 38 and the next gripper has reached the position to receive a sheet, normally closed contacts of switches 40 and 42 are opened, de-energising holding coil H3 and releasing relay R3. Contacts R3-2 close and the relay R2 is energised. The platform 154 is lowered until'the sheets are spaced below the light beam, as described above. During this operation, the relay R3 cannot be energised, because the contacts R2-2 are opened.

[0064] Finally, after the last sheet of the last set has been stacked on the platform 154, and the platform 154 raised to the upper position, an operator can conveniently remove the collated stacked sets. If the full capacity of the apparatus is reached before the finishing of a job, the platform 154 operates the lower limit switch 244 to open the normally closed contacts thereof. This prevents energisation of relays 2 and 3, thus stopping the collation process. The line 274 is earthed automatically or manually, for example, by setting the counter 276 to zero, and the relay Rl energised to raise the platform 154 to the upper position.

[0065] The collated stack of sheets is then removed and the sequence restarted, by resetting the counter.

[0066] In the timing diagram of Figure 9, time TO represents the time before operation begins and time Tl the time at which the first sheet arrives at switch 38. Between times TO and Tl, the counter 276 is set, disconnecting the line 274 from earth. The solenoids 256 and 268 are de-energised and the arm 250 pivots to position A. The motor 194 is energised to lower the platform 154 until sensor unit 278 indicates non-obstruction of the light beam.

[0067] At time Tl, the arrival of the first sheet of set 1 initiates advance of the grippers by energisation of motor 78. Shortly after, switch 40 is released from contour 100. When switch 42 is engaged by contour 124, motor 78 is de-energised.

[0068] At time T2, the arrival of the first sheet of set 2 restarts advance of the grippers by energisation of motor 78. Shortly after, switch 42 is released from contour 124. The first sheet of set 1 is deposited on platform 154. When switch 40 is engaged by contour 100, motor 78 is de-energised. As the first sheet of set 2 has operated switch 282 at the entrance to station 22, the relay R4 is energised and held by the holding coil H4. This energises the solenoid 256 to move the arm 250 to position B.

[0069] At time T3, the arrival of the first sheet of set 3 restarts advance of the grippers by energisation of motor 78. Shortly after, switch 40 is released from contour 100.

[0070] The first sheet of set 2 is deposited on the first sheet of set 1 on platform 154. When switch 42 is engaged by contour 124, motor 78 is de-energised.

[0071] This sequence continues until time T9 when the first sheet of set 9 arrives. This initiates a cycle similar to that after time Tl, except that line 274 is at earth potential. Holding coil H3 continues to be energised by closure of switch 282, when switch 42 is engaged by contour 124, so that motor 78 continues to be energised at and after time T10, when no further sheet arrives (compare time T250). The first sheet of set 9 is deposited on the first sheet of set 8 on the platform 154. When switch 40 is engaged by contour 100, motor 78 is de-energised.

[0072] There is now no sheet to operate switch 282, so that holding coil H3 is de-energised, releasing relay R3. Relay Rl is energised through earthed line 274 and contacts R3-l. This energises solenoids 256 and 258 to pivot arm 250 to position C and relay R5 to energise the motor 194 to raise the platform and stack to the upper position.

[0073] Before time Tll, when the second sheet of set 1 arrives, the counter 276 is reset and the relay Rl de-energised. This de-energises the solenoids 256 and 268 to allow the arm 250 to return to position A, and allows the sensor unit to energise relay R2 to drop the platform 154 to below the light beam, leaving a corner of the stack supported by the roller 252 on the arm 250 as described above.

[0074] At time Tll, the second sheet of set 1 arrives and the cycles of operation at times Tl to T10 are repeated, the second sheets being inserted in the stack which is separated to receive them in collated fashion. The operation is repeated as the additional sheets of all the - sets arrive, with no significant change in operation until the height of the stack obscures the light beam as depicted by one example between the times T₁₉₈ and T199.

[0075] At time T₁₉₈, the twentieth sheet of set 8 actuates switch 38. The sensor unit provides an earth potential on line 280 as set 7 is lowered onto the platform 154 by pivotation of the arm 250 to position B. This causes the motor 194 to be energised to lower the platform 154, until the light beam is not obstructed. Then, the operation continues.

[0076] At time T₁₉₉, the twentieth sheet of the set 9 arrives and the counter 276 goes to zero and applies an earth potential to line 274. Relay R3 is energised at this time, so that relay Rl cannot be energised and relay R3 remains held by holding coil H3 from time T₁₉₉ until after time T₂₀₀, when no sheet arrives, but the twentieth sheet of set 9 is inserted into the stack. After such insertion, switch 282 is no longer operated and when switch 40 engages contour 100, holding coil H3 is de-energised, releasing relay R3, so that relay Rl is energised. This energises relay R5 which energises the motor 194, causing the platform 154 to be raised.

[0077] After time T_248' when the twentyfifth sheet of set 8 arrives, the operation is similar to that after time T198.

[0078] At time T₂₄₉, the twentyfifth sheet of set 9 arrives and the operation continues as previously described after time T₁₉₉. At time T₂₅₀, when no sheet arrives, the relay R3 continues to be held by holding coil H3, as there is a sheet operating switch 282 and still to be inserted. After.insertion of the last sheet, the gripper 84 arrives in position to receive a sheet, the switch 40 being actuated by contour 100. The relay Rl is energised, energising the relay R5 and the solenoids 256 and 268. The arm 250 is moved to position 3 and the motor 194 energised to lift the platform 154 and stack of collated sheets.

[0079] With the platform 154 in the upper position, the switch 242 is opened and the relay R5 de-energised. This stops the motor 194 and the apparatus at time T₂₅₁ is in the same condition as at time TO.

[0080] It will be observed that with an odd number of sets to be collated, the apparatus performs that number plus one cycle for each sheet. With an even number of sets to be collated, the apparatus will perform that number plus two cycles for each sheet in order to bring the first gripper 84 back to the home position. It will be appreciated that many variations may be made in the precise mechanical and control details of apparatus for performing the invention within the scope of the appended claims.

Claims

1. A method of collating sets of sheets, which are received serially in groups of similar sheets, comprising the steps of stacking the sheets of the first group received in individually offset fashion, demarcating each first sheet from adjacent first sheets, and inserting individual sheets of the next group in the same offset fashion contiguous to individual first sheets, and thereafter inserting, if necessary, individual sheets of subsequent groups in the same contiguous to individual prior-inserted sheets of the same set to form collated sets of sheets.

2. A method according to Claim 1, including the steps of separating adjacent stacked sheets at the appropriate location prior to the insertion of a sheet.

3. A method according to Claim 1 or 2 in which the first inserted sheet of each group after the first is inserted behind the previously inserted sheet of the first set.

4. A method according to Claim 3, in which the first inserted sheet of each group after the first is inserted below the previously inserted sheet of the first set.

5. A method according to Claim 1, 2, 3 or 4, in which the offset is achieved by skewing sheets alternately in opposite directions prior to stacking or insertion.

6. A method according to Claim 5, including the steps of lifting an offset corner of stacked sheets, inserting the next sheet, dropping the stacked sheets, and lifting the next opposite corner of stacked sheets prior to insertion of the next following sheet, and so on.

7. Apparatus for collating sets of sheets, which are received serially in groups of similar sheets, comprising means to stack the sheets of the first group received in individually offset fashion, demarcating each first sheet from adjacent first sheets, and means to insert individual sheets of the next group in the same offset fashion con- . tiguous to individual first sheets and to insert, if necessary, individual sheets of subsequent groups in the same fashion contiguous to individual prior inserted sheets of the same set to form collated sets of sheets.

8. Apparatus according to Claim 7, including a movable sheet platform for receiving and maintaining sheets in offset fashion.

9. Apparatus according to Claim 8, in which the movable sheet platform is movable vertically.

10. Apparatus according to Claim 7, 8 or 9, including means for separating adjacent stacked sheets at the appropriate location prior to insertion of a sheet.

ll. Apparatus according to Claim 7, 8, 9 or 10, including offsetting means operable to skew sheets alternately in opposite directions prior to stacking or insertion.

12. Apparatus according to Claim 11, in which the offsetting means comprises alternately offset sheet gripping means movable to co-operate with camming means to open the gripping means to receive a sheet and to release a sheet.

13. Apparatus according to Claim 11 or 12, including means to lift alternate corners of adjacent stacked sets prior to individual sheet insertion.

Drawing