CA2131554C - Apparatus for stacking sheet-like articles - Google Patents

Abstract

An apparatus for stacking a plurality or flat articles on edge, comprising a dis charge magazine (16), the discharge magazine including moveable discharge support belts (68a, 68b) and a moveable co mpression plate (70). A stacker section adjacent the discharge magazine transport articles sequentially into the stack, the stacker s ection comprising stacker belts (26a, 26b) extending around a plurality of rollers (28a, 28b, 30a, 32a, 32b). The last of the article s in the stack abuts against the stacker belts adjacent one of the rollers (32) to apply a compressive force developed by the stack of f lat articles and the compression plate to the one roller. The one roller is movably mounted to the apparatus for movement responsi ve to increases and decreases in the compressive force. A deflection plate (150) is positioned proximate the one moveable roller to deflect leaning sides of the articles. An actuator element (20) is operatively connected to the one roller and connected t o the drive element for activating the drive belts and the discharge support belts.

Description

WO 93/18996 P~/US93/0~731 APPAR~TUS FOR STACKING S~I~T LIRE ARTICLES

~ield of Invention The present invention relates generally to an apparatus and method for stacking sheet-like articles, and more particularly to a ~evice for controlling the pressure in a stacX when stackiny sheet~ .e articles such 2S
envelopes that are continuousiy being fed into ~he stack.
-Backqround of the Invention Envelope processing systems, such as mail piece processing, sorting and bar code application systems, typically include an envelo~e stacking apparatus at the end of the system to secure the sorted r..ail pieces in a stacked position to facilitate orderly re~oval of the processed mail pieces from thé system. The stacked mail pieces are manually or automatically removed from the stack and/or bound by an operator.
One such stacking apparatus is disclosed in ~.S.
Patent ~o. 4,955,596, commonly assigned. An envelope to be stacked, or any suitable sheet-like article, is forcibly fed on edge into a discharge ma~azine where it is stacked in a somewhat compressed array with other, previously fed envelopes. The envelope enters the discharge magazine via a dual stacker belt transport configuration, wherein a pair ~ 3~
WO93/18996 ~ PCT/~S9~/02731 '' vertically juxtaposed stacker belts rotate about roller~
disposes in a triangular array. The rollers each are rotatablv mounted on shafts h~ving a fi~ed a~s.
The discharge magazine includes multiple transp~r. belts that may have smooth surfaces, or may have track-like protrusions extending above the discharg~
magazine floor to engage the bottom edges of the stacked envel~pes and advance the envelopes away from tne stacker belts to pe'rmit the free entry of additional envelopes into the stacker region. The transport ~elts are activated b~
a stac~; sensor mechanism that includes a spring biàsed, pivotal1~ mounted lever arm which extends through a gap between .he pair of s~ac~.er belts. The tip of the lever ar~ contacts the last envelope to enter the stack. As the stack ge~s larger and the laterally,applied normal force of the stacked envelopes overcomes the bias of the lever arm spring of the sensor mechanism, the lever arm trips a switch that in turn activates a drive motor connected to the tr2nsport belts to move the envelopes away from the stacker Delts. This reduces the normal force or pressure exerted ~y the stack of en~elopes on the stacker belts, and provides space for the entry of subsequent envelopes into the stac~.
Although the stack sensor lever arm in the prior art apparatus contacts the last envelope in the stac~, the lever a~ contacts the last stacked envelope over a-small plane, or sometimes a point, and is therefore highl~
suscepti~le to planar and height variations associated with the last stacked envelope. In high speed mail processing systems, a p~ro~lemi arises when the last envelope in the stack tilts such that the bottom edge and the top edge of the envelope no longer form a substantially vertical plane.
As the stack becomes increasingly tight, accurate pressure sensing is critical to avoid jam~ing. Jamming occurs as a consequence of erroneous stack pressure sensing, when a tilted edge of the last stacked envelope obstructs the entrance to the stack of the next envelope to be stacked.
Such problems are compounded when the stacker is used for ~ WO93/18996 3 PCT/US93/02731 , .
simulta-.Dously stacking a pluralit~ of different si?
(varyin- in height and thickness) envelopes.
Erroneous stack pressure sensing typically occurs where .:~e lever arm contacts the tilted envclope ~t ~
surface or point that is tilted furthest awa~ from the stacker ~elts. This surface eY.erts less force on the l~ver arm th2~ the surface closest to the stacker belt. The lever a~'s smal-l plane or point o~ contact may crroneousl~
indicate that the stack can receive more envelopes when the stack is actually too ticJht to properly receive another envelope without first activating the transport belts.
In view of the foregoing, an object of the present invention is to provide a high speed stac~:ins apparat-s and method that accurately senses the stac}:
pressure of tilted articles to substantially reduce the occurre,.ce of article jamming.
Another object of the present invention is to provide an apparatus and method that automatically and a~curate1y senses the p~essure applied by a stacked group of processed envelopes on a stacker conveying mechanism regardlPss of the degree of tilt of the last envelope to enter t~.2 stack, and in response thereto generates a signal to actuzte an envelope transport system for advancing thc documen.s in the stack away from the stacker conveyor means, .hereby relieving the pressure on the conveying mechanis~ and creating space for the facile entry of additional processed envelopes into the stack.
A further object of the present invention is the provisic~ of a sensor apparatus for a conveying belt mechanism fjor an enyelope stacker device whereby one of the roller elements supporting the belt mechanism is on a laterally displaceable axis, whereby the axial displacement of the roller element is responsive to the force applied to the sensor apparatus by the stack of envelopes regardless of the angle of vertical orientation of the envelopes in the stack as the envelopes en~age the sensor apparatus.
Yet another object o~ the present invention is the provision of an automatically actuated kicker mechanism that senses the trailing edge of an envelope entering the . ... , . . . . . . ........ , .. .~.. , . - - -.- - ., .-., .. . . ~ . . .

.~3 ~Si~ L PCT/US93/0273l stac~ d ~icks the trailing edge ~way from the conveyo~
belts ~.~d onto an auger which drives the envelope~s trackin~ edge outward to oooperate ~.ith the stack pressure sensor z~d control device to ensure that space is provided in the ~,ack to permit subsequent envelopes to be fecl into the stac-: without jamming.
Another object of the present invention is to provide an adjustable deflection element for a stacker apparat~s of the type described above, which deflection plate -..aintains larger sheet~ e articles in a substan~ially upright manner as they enter the stacker, and prevents these larger articles from leaning into or a~ainst the mo~eable roller, which would result in a ~alse detectic~ of pressure against the moveable roller.

Summary of the ln~ention The above objects and advantages are provided ~y the app~atus and method for stacking sheet-like articles disclos~ herein. The in~ention i~cludes an envelope con~eying apparatus for stacking a series of se~uentially fed sheet-like envelopes. The apparatus includes an elastic stacker belt assembly, one element of which comprises a movable roller element forming part of the conveyir.g means, such as a spring biased roller, for sensing ~ force exerted by the stack of articles on the envelope conveyin~ apparatus.
One embodiment of the invention comprises an envelope conveying apparatus having a dual belt system which e~:tends around a portion of the moveable sensinc~
roller 2nd feeds the~ envelopes directly and sequentially into the stack. The moveable sensing roller also varies the tension of the conveying belts ~s a ~unction of the force e~erted by the stack of articlcs on the stacker belt system..
This embodiment of the invention includes a moveable dual belt system support~d by a plurality of rollers, which belt system comprises the means for conveying envelopes into a stac~. of previously fed envelopes. One of the rollers is located adjacent the .. ... . , , ~ ,., . ... ... ~ . .... . ... .. , ~, .. .. ... .. .

~31a~
WO93~18996 ~ PCT/U~93/02731 stac~ o. envelopes, whereby the portion of the conveyo~
belt s~stem passing over that particular rolle~ is in contact ~~ith the stack of envelopes, and specifically i,~
direct c~ntact with the most recent envelope added to the stack. This one roller is rotatably supported on an axially ~oveable shaft disposed, in one embodim~nt, at on~
end of a lever arm, which lever arm is pivotally mounted to the base of the stacking mechanism. The other end of the lever anm, which is beyond the pivotal mounting point, includes means for biasing the lever arm such that the roller on the opposite end of the lever arm is urged toward the stac'.~ of envelopes. The belt portion extending around the axi271y moveable roller is biased to pivot into contact with the stack of articles with a force that counteracts the ever increasing force applied by the stack against the envelop2 conveying belt system. The force of the stac~
moves t-e axially moveable roller, which then acts as a sensing ~eans to detect when the stack force or pressure reaches a predetermined maY.imum value. When this value is reached, the movement of the roller activates a motor operatec drive mechanism which causes a horizontally disposed belt transport syst~m upon which the stack of envelop~s is supported to move the stack of envelopes away from, ar.d relieve the pressure upon, the belt system of the envelope conveyinq means.
Another embodiment includes an envelope conveying system having a moveable roller element forming part of the conveying means and a deflection means for preventing articles from improperly leanin~ into the moveable roller element and trigge~ing a false sensing of the force exerted by the s ack of articles.~
Another embodiment includes an envelope conveying system having a roller moveable in a substantially linear direction and a biasing element, such as a spring, operably coupled to the roller support structure for counteracting the force exerted by the stack of articles on the belt system of the envelope conveyin~ means.
Another aspect of the present invention provides a kicker arm assembly which senses the trailing edge of an . .

W093/18996 PCT/USg3/0273!
envelope ~n~ering the stacker region adjacent the envelo~e conveyc~- belt system, and applies a force to kic~: the trailin~ edge of each env~lope away from the belt system and onto an auger to providc ~dditi~nal force to move th~
trailinc edge of each docum~nt ent~ring the stac~ ot~t of the path of the leading edge of each subsequently fed envelope.
The method of the present invention for stacking sheet-like articles on edge of the present invention includes: conveying the individual documents into a stac~
of docu~ents; sensing the force exerted by the stac~ of documen~s on a stacker inf~ecl b~lt regardless of the angular disposition of the last documents added to the stack, and reducing the force e~erted by the stack of documents on the stac~.er belts in response to the sensing of the force by moving the stac~ of documents in a direction away from the sta.cker belt system.

Brief De~criPtions of the Drawinq~
~ ig. 1 is a top view schematically depicting a stacking apparatus constructed in accordance with the pres~nt invention, with the envelope kicker mechanism not shown:
~ ig. 2 is a front elevation view of the stacker belts and kicker mechanism forming the document drive of the present invention, with a portion of the stacker belts and rollers cut away to illustrate the ~icker mechanism, ~ ig. 3 is a top view schematically illustrating the kicker arm assembly of the present invention for kicking the trailing edge of each envelope away from the envelope conveying belt system and onto an auger element;
Fig. 4 is an additional embodiment of a moveable ~ sensor mechanism constructed in accordance with the invention;
Fig. 5 is a partial front elevation view of a further embodiment of the stacker apparatus, including a deflection plate for supporting the upper surface of documents entering the stacking apparatus;

~13I~j'54 WO93/18996 7 PC~/US93/02731 Fig. 6 is a top plan view schematically depicting a stac};ing apparatus with a deflection plate in accordance with the invention illustratc(1 in FIG. 5; and Fig. 7 is a top plan view schematically depicting a further embodiment of ~ st~c~ing apparatus havin~ a deflection plate in accordance with the invention.

Detailed Description of the Preferred Embodiment Fig. l generally illustrates the preferred embodiment of the stacking apparatus lO of the present invention having an introductory conveying path 12 for ~
document such as an envelope 14, a controllable discharye or docu..,ent transport magazine 16, a stacking belt assembly 18, and a movable roller sensin~ mechanism 20. The introductory document conveying path 12 includes a feed belt 22 rotatable a~out a plurality of rollers 2~ which ,drive belt 22 in the dir~ction shown by arrow A.' The path 12 may accept envelopes from a prior envelope feeding stage or othe~ envelope processing stage. The feed belt 22 drives the envelope into contact with the stac~ing belt assembly 18 by virtue of the spatial proximity of the two belt assemblies. Alternately, feed' belts 22 may comprise a pair of vertically separated O-rings extended over pulleys used in place of rollers 24. The 0-rings are adapted to provide the same function as belts 22, which is to advance an envelope,into contact with stac~ing belt ~assembly 18, as will be explained.
As seen in FIGS.' l and 2, the stacker belt assembly 18 comprises a pair of elastic stacker belts ~6 and 26b rotatable about axially fixed dual idler rollers 28a and 28b, axially fixed drive rollers 30a and 30b, and axially movable dual rollers 32a and 32b. Moveable roller - 32 is rotatably mounted on a shaft 34 which shaft is mounted on a pivotally mounted lever arm 36. Lever arm 36 is rotatably mounted on a shaft 38, which in turn is fixed to a base plate 40 and a top plate 42 (FIG. 2) which form part of the static support assembly for the stac~ing apparatus lO. ' W093/18996 ~ ~ 3 i ~ 5 4 PCT/US93/02731~ ' The stacker belts 26a and 26b extend about a triangu:ar course of travel formed by the rollers 28a, 2~b, 30a, 30_, 32a and 32b. A drive shaft 44 is connected to a prime r~ver and to rollers 30~ and 3Ob, and drives the axially fi~ed drive rollers 30a and 30b ln a clocXwlse direction as viewed in FIG. 1. ~s will be explained,.shaft 34 supporting rollers 32a and 3~.b is axially biased toward the sta~k of envelDpes 46, and forces a portion 64 of belts 26a and 26b outwardly and into contact with t~e last stacked envelope 50 of the stack 46.
The movable roller sensing mechanism 20 includec;
the a~ially moveable dual rollers ~2a and 32b, lever arm 36, and a biasing mechanism generally denoted 52. Lever arm 36 has a first end 54a and a second end 54b. Moveable rollers 32a and 32b are attached to the first end 54a, and are rotatable about shaft 34 and axially pivotal about shaft or post 38, as previously described. The second end 54b of arm 36 en~ages one end of biasing mechanism 52 via an adjustable screw 56. The distal end of the biasing mechanism 52 is secured to a non-movable post 58. The biasing mechanism 52 extends through the space between du~
stacker belts 26a and 26b (FIG.. 2). Adjustable screw 56 extends toward the wand 60 of a switch mechanism comprising microswitch 62j- whereby the movement of screw 56 actuates the microswitrh.. .As viewed in ~IG. 1, biasing mechanism 52 biases lever arm 36 in a counterclockwise direction arouncl shaft 38, forcing rollers 32a and 32b and belt portion 6 outward towards envelope stac~ 46.
~ top member 66 provides a limit to the counterclockwise rotation of the lever arm 36 and moveable rollers 32a and 32b about shaft 38. The biasing mechanism 52 serves to urge the lever arm 36 away from the switch mechanism 62. Switch mechanism 62 is electrically coupled to.a motor or other prime mover (not shown) that controls the movement of magazine conveyor belts 68a and 68b.
Discharge magazine 16 includes conveyor belts 68a and 68b, an adjustable compression plate 70 slidable along guide rod 72, and a document stop element 74. Each conveyer belt 68a, 68b, extends around a pair of pulleys ~3i ~5~
W093/18996 g PCT/US93tO2731 (not s;~-~n). One of the pulleys associated with each belt 68a, 6c~ is driven by a suitable motor, which ~otor is operati.ely connected to ~nd act-1~ted by switch 62. Th~
conveyc- belts 68a and 68b transport the envelopes in stac~.
46 in 2 direction shown by arrow 76, and are activated by the mot~r when the ~djustab~e screw 56 contacts the switch.
mechanis~ 62. The stack of envelopes 46 is vertically disposec on top of and supported by belts 68a and 68b.
After the last to be stacked envelope 50, as ~ill be expl2'ned, reaches discharge magazine 16 and the leadi.ng edge of envelope 50 abuts stop element 74, portion &4 of stacXer ~elt 26 holds envelope 50 at an angle relative to the lon~itudinal direction of magazine 16. In addition, portion 78 of belt 26 extends away from discharge magazine 16 on th2 upstream side of rollers 32a and 32b relative to belt po-_ion 64. As a result, a variable entrance angle 80 is forme~ between envelope 50 and belt portion 7~. This i5 the en_rance angle through which envelopes 14 are transpo~,ed to stack 46.
The present invcntion also includes a kicker arm assembl~. 82 (FIGS~ 2, 3) for kic~ing the trailing edge of each en~elope 14 away from belt portion 78 and onto auger ~4. Auger 84 (FIGS. l, 3) comprises a helix 8~ rising slightl~ above the upper surface of base plate 40 which engages _he bottom edge of each envelope 14 as the envelope is kic~.ed away from belt portion 78 by ~icker arm assembly 82. The auger 84 moves the trailing edge of each envelope 14 thro~gh entrance angle 80, thereby creating a space for the adv2ncement of the next envelope into the stack 46 without causing interference with the trailing edge of the preceding envelope.
Kicker arm acsembly includes a vertically disposec mounting bracket 86 fixed to base plate 40, as best see~ in FIG. 2. A mounting plate 88 is fixed to and extends from the top of bracket 86, and an aperture 90 extends through an outer portion of mounting plate 88 Shaft 92 is rotatably mounted through aperture 90, and extends downward through an aperture in base plate 40. The lower end of shaft 92 is attached to the operating shaft 94 W093/1~996 ~ ~ O PCT/US9~tO2731 of a rc.ary operating solenoid 9~. Shaft 9~ is adapte~ ~o be rota.ed thro~gh a limited circl~lar angle when solenoid 9 6 i S 2 c.uated.
A pair of extendahle arms 98a, 98b are fixed to shaft 92, ~nd a pair of kic}:er arms lOOa, lOOb are attache~
to exter.~able arms 98a, s8b respectiYely. Kic~er arm lOOa is vert~cally located on shaft 92 such that when shaft 92 is rota~ed by solenoid 96 in the counterclockwise direction as viewed in ~IG. 3, kicker arm lOOa extends between belts 26a anc 26b. In similar ~ashion, kicker arm lOOb is vertiral~y located on shaft 92 such that when shaft 92 is rotated counterclockwise (FIG. 3) by solenoid 96, kicker arm lOo- extends in the space bet~leen belt 26b and the upper s~rface of base plate ~. When solenoid 96 is actuatec, shaft 92 rotates in a cloc~wise direc:tion (FIG.
3), mov~ng kicker arms lOOa and lOOb to the retracted position seen in FIG. 3. When solenoid 96 is de--activated, a sprinc, mechanism (not shown) biases the outer ends of kicker 2~ms lOOa and lOOb to eY.tend outward beyond the vertic2l plane of belt portions 78 to engage the trailing edge oi 2 moving envelope 14 as tne .envelope is driven towards ~he stack 46, thereby driving the trailing edge of the envelope through angle 80 and onto auger 8~ and hel~
85. The helix drives the trailing edge of the envelope in a direction away from belt portion 78, providing space for the trar.sport of the next enve.lope into the stack without .iamming .
A photocell sensor element 102 (FIG. 3) is mounted on base plate 40 adjacent the path traveled by each envelope l~ and just ahead of mo~1nting brac~et 86. Sensor element 102 is èlectrically connected through line 103 to solenoid 96. As each envelope l~ advances, sensor 102 -- detects the leading edge of the envelope, and sends a signal through line 103 to actuate the solenoid, rotating shaft 92 clockwise tFIG. 3), thus retracting ~icker arms lOOa, lOOb out of the path of the advancing envelope. ~s the envelope 14 moves forward, sensor 102 eventually detects the trailing edge of the envelope, and sends another signal through line 103 which de-actuates solenoid .. ,, ., ,.. ,. .... ........ .. .. .. . . . . ... . . ~ .

~i3:~ j4 1 ~

96, wh~reby the spring mechanism rotates shaft 92 counter~lockwise, extending }:icker arms lOOa, lOOb outward beyond he vertical plane of belts 26a, 26b. ~s stated previo~sly, kicker arms lOOa, loob force the traili~g e~
of the e~elope 14 outward and onto auger ~4. The vertical location of kicker arms lOOa, lOob is preferably fixed sucl that th~ arms will contact regular sized envelopes as ~ell as flat or larger sized envelopes.
In the operation of the embodiment disclosed in FIGS. 1 and 2, an envelope 14 is conveyed by the stac~ing belt assembly 18 along linear introductory path 12 ùntil the lea~'ing edqe of the ~nvelope 14 contacts the most recentl~ stacked envelope 50 after passing through the acute e~.irance angle 80. ~s the stacker belts 26a and 26b move, t:~e leading edge of each envelope 14 is bent around bend point 104 and interposed between the most recently stacked envelope 50 and portion 64 of stacker belts 26a and 26b. he trailing edge of the envelope is displaced through the entrance angle 80 with the aid of auger ~ so that the trailing edge "fishtails~ through the entrance angle. The bottom margin of the trailing edge o~ the envelope 14 is engaged to ride in the helical threads 85 of t~e rot2ting auger element 8~ to propel the trailing edge of each envelope 14 into the stack and away from stacking belt assembly 18 to provide space for subsequently fed envelopes.
The present invention includes a unique sensing mechanis~ that p~ovides a broad plane of contact with the last st~cked envelope and also varies the stacker belt tension about the rollers 28a and 2~b, 30a and 30b, and 32a and 32b. The moveable roller sensing mechanism 20 forms part of the stacking belt assembly 18. As more envelopes ~ are sequentially stacked in the discharge magazine 16, a normal compressive force or pressure is developed in the stack 46 in opposition to the bias element 52 exerts on the moveable rollers 32a and 32b. This normal force causes the lever arm 36 to rotate in a clock~ise direction, thereb~
slightly decreasing the entrance angle 80 and reducing the tension on the stacker belts 26a and 26b. When the force '~13 ~ 55~
W093/18996 l 2 PCT/US93/02731 applieà 2~' the stack 46 to the movai,ie rollers 32a and 3CL~
exceeds ~he force applied to the moveable rollers by the biasing mechanism 52, the adjustable screw 5G engages microsw~,ch 62 and activates the motor drivin~ maga~.ine conveyo- belts 68a and 68b.
The conveyor belts 68a and 68b then convey the envelopes away from the stacker belts 26a and 26b in the direction of arrow 76, thereby relieving the pressure force previously exerted on the movahle rcllers 32a and 32b an~1 allowinc the lever arm 36 to rotate in the counterclockwise directicn under the bias of mechanism 52. This causes th~
adjusta~le screw 56 t~ disengage from switch mechanism 62 which de-activates the motor connected to magazine conveyor belts 6~a and 68b. The envelopes in the front part of stack 6 fan out as pressure i5 relieved, allowin~
additional envelopes to be sequentially fed into the stac~
with~ut interference from the trailing edge of previously stacked _nvelopes.
- Undesirable variations in pressure sensing by the movable r~ller sensing mechanism 20 due to slack in the stacker belts 26a and 26b is further reduced by the direction of movement of the stacker belts 26a and 26b.
The drive roller 30 rotates clockwise as viewed in FIG. l, and pulls the stacker belts 26 tightly over movable rollers 32a and 32b while "pushing" the stacker belts 26a and 26b toward idler rollers 28a and 2~b~ 1'herefore, any slacX in the stack.er belts 26a and 26b is developed in the top run of the .riangular path between drive rollers 30a and 30b and idler rollers 28a an~ ~b. Belts 26a and 26b remain taught 25 they travel from idler rollers 28a and 28b to axially moveable rollers 32a and 32b, and from moveable idler rollers 32a and 32b to drive rollers 30a and 30b.
This taughtness of belts 26a and 26b adjacent rollers 32a and 32b enhances the accuracy of roller sensing mechanism 20.
As illustrated in FIG. 2, the lever arm 36 is vertically situated adjacent the gap between stacker belts 26a and 26b. Shaft 38 and non-moveable stop member or post WO93~189g6 ~ 5~ PCT/VS93/02731 66 are i~edly secure~ to ba~e ~late ~0 via a_tachl~ent bolts 1:~, 112.
The plane of contact between th~ movable roll~
sensins -,echanism 20 and envelopes 14 comprises the brG~d surfaces of the dual stacker belts ~6a and 26b, rather thar.
a separ2-e rod or arm type sensing lever with a small plan~
of cont2-t, as found in the prior art. The stacker belts 26a anc 26b of the present invention are used both to transpo-_ envelopes directly into the stack 46 and also to form a _-oad pressure sensing surface which senses stac~
pressur_ accurately regardless of the tilt of the forward envelopcs.
Kic~.er arm assembl~ 82 cooperates with the stac~inc belt assembly 18 and the roller sensing mechanism 20 to mc!e the trailing edge of each envelope away from the path o_ subsequently fed envelopes as each prior envelope reaches ~he stack 46. As described previously, kicker arm assembl~. operatPs to kic~. the trailing edge of eacl~
envelop_ ~s it reaches the stack in a direction toward the stack z..~ onto auger 84, and out of the primary path o~
envelo~2 .ravel, as defined by introductory conveying path 12 and _~lt portion 78 of stac~ing ~elt assembly 18. The trailinc edge of each envelope is therefore removed from possibls interference with the leading edge of an incoming envelopc. As the number of unimpeded envelopes enterins the stac:. increases, t,he normal' force applied by the stack of envelopes against the roller sensing mechanism 20 increases to the point where the compressed stac~ oi envelope~ presents another impediment to rapid introduction of envelopes into the stack, ~s explained, when ~he normal force reaches a predetermined limit,, the maga~ine conveyor belts 6ca and 68b are driven to relieve the stack pressure adjacent the stacking belt assembly 18~ ' As appreciated by those having ordinary skill in the art, a single belt 26 configuration may also be suitable, provided the width of the belt 26 that forms the contact surface is proportionally wide enough to contract a substantial portion of each envelope.

WO93/18996 ~3 ~5 S 1 4 . PCT/US93/02731 Fig~ 4 illustrates 211 alternative embodiment of the rol e- sensing mechanis~ of ~he present inventi.or., compris~ns a substantially line~rly ~ovin~ sens~r element.
A sprin~ loaded sensing roller 20' replaces the roller sensin~ ~echanism 20 shown in FIGS. l, 2 and 3. As illustrz_ed in FIG. 4, linear dis~lacement occurs in the horizont~l directionj as indicate~ ~y arro~ 120, as opposed to the -o~ational displacement of the moveable sensing mechanis-~ 20 of FIG. l. A hollow cylindrical member 122 is fixedly ..ou~ted to a vertically extending sleeve '2~
through ~hich rotatable shaft 3~ e~:tends. Moveable roller 32 is ~tatably mounted on shaft 3~.. The cylindrical member '2~ houses biasincJ elemc-nt 126, which is substant~ally restricted to linear move~ent by quide plates 128 anà ~,0. A lever 132 is attached to an end of sleeve 124, an- is adapted to contact and m~ve wand 13~. of micros~ ch l36.
~ The operation of the alternate embodiment of FIG.
4 is sir lar to the operation of the embodiment of FIG. l.
As stac:: pressure increases, moveable roller 32' moves horizont21ly in the direction of the application of stac}
pressure, driving shaft 3~1', sleeve l24, hollow cylindrical member '22 and lever 132 in the same direction. When the stack pr~ssure has reached a predetermined maximum limit, lever 132 comes into contact with wand 134, activating microswi~ch 136 and.moving magazine conveyor bel.ts 68a and 68b in 2 direction away from stac}:ing belt assembly 18.
Although 2 spring is shown as a representation of biasing element 126, oth~r suitable biasing elements can be su~stitu_ed therefor.
When tall articles are stacked, such as catalogues and magazines by way of example, a top edge may -- lean to~ard the moveable roller 32 while a bottom edge stays close to the other articles in the stack. The top edge causes the moveable roller to advance in a clockwise directi.on falsely indicating the compression force as truly represPnted by the entire stac~ of articles. Consequently, the con~eyor belts 68a and 68b may be activated at an ~3 ~5~
WO93/18996 1 5 PCT/US93/0~731 incorre_~ time in response to the pressure ca~sed by thc leanins article.
Figs. 5 and 6 illustrate an embodiment of the invention including a deflection plate 150 for eliminatlr~;
these tvpes of false detections. The moveable roller 3~ is shown i~ Fig. 6 sensing the predetermined maximum force from the stack of articles, and is in its extreme clockwise positicn. The deflection plate 150 is located vertically above ,he top plate 42 and lies in a horizontal plane paralle~ to both the top plate 42 ar.d the base plate 40 (as seen in r ig. 5). The deflection plate 150 includes an arc-shaped slot 151 positioned to arcua~-~ly slide about shaft 38 (as ~est seen in Fig. 6~. The deflection plate 150 pivots :nsrizontally about drive shaft 44 in the directions shown bv arrows 152.
Adjustment of the deflection plate 150 occurs by looseni~.g a lock nut 153 and sliding the plate 150 to its desired position. After positioniny the plate 150 to the desireà position, the lock nut 153 is tightened to secure the pl2 .e in place.
The deflection plate 1~0 is defined b~ a curved outer deflective edge 154 (best seen în Fig. 6) formed in part to coincide with the path tr~veled by the transport belts about the moveable roller 32 and stationary roller 30 when the moveable roller is in its most cloc~wise position.
The deflective edge 15~ serves as a deflection surface about the moveable roller 32 to force leaning sides of the articles away from the moveable roller and into an upright position to prevent inadvertent pressure against the moveable roller.
.
The deflective edge 15~ faces the stack of articles and extends outwardly tot~ard transport magazine 16. The deflective edge 15~ extends outwardly to a maximum distance shown at A, generally coincident with the abutment surface of the transport belts 26a, 26b when moveable roller 32 is in its maximum clo~}~wise position (e.g., when the moveable roller 32 senses a maximum force from the stack of articles). This distance may vary depending upon the rigidity of the articles.

bl~lS5~, WO93/18996 1 6 PCT/~'S93/0273l The deflective edge 15~ may be any length extendi.-g along the path of the transport belts 26a, 2~b suitabl~ ~o properly deflect articles. The len~'h of ed~
154 may zlso vary depending upon the type of articles to b~
stackec and/or the path of the transport belts. Th~
defl2c~ion surface may be a line of contact made by ~
wedge-s:-aped edge on the plate 150 or may be a surface of an "L"-shaped member whose stem contacts the ar'icle, or may be -nv other suitable contact surface.
The distance between the base plate 40 and the deflec~ion plate 150 (Fig. 5) is a predetermined distance corres~_nàing to a portion of the transverse width (edge to paralle: edge) of the flat surface of the widest article to be tran_?orted by the transport belts thereb~ ensurin~ that the flz_ surface of the article will not lean into the movea~le -oller 32.
In operation, when the leaning edge of a stacked article i~;properly leans toward the moveable roller 32, the deflection plate 150 prevents the leaning edge from leaning too far toward the moveable roller. The bottom edge is . ~
allowed to move toward the moveable roller. As more articles are stacked, the stationary deflection plate forces ~he stacked articles to straighten. Consequently, the deflection plate lS0 prevents articles from leaning into the ~oveable roller 32 si~naling a false detection of maximu~. pressure against the moveable roller. As the articles strai~hten, a more uniform compression force is applied to the moveable roller.
Fig. 7 depicts a deflection plate 160 havin~ a shorter deflection edge 162 compared to the deflection edgc 153 on plate 150. The shorter deflective edge 162 does not extend ~o the' fixed roller 30 but only extends about moveable roller 32. The deflection plate 160 is rotatable about shaft 44 and ~lida~le about shaft 38 in the same manner 2S deflection plate 150 as previously described with reference to Figs~ 5 and 6.
While the invention has been particularly shown and described with reference to the preferred embodiments thereof, it will be understood by those having ordinary ;~ 1 3 1 i~
WOg3/18996 1 7 PCT/~'S93~02731 skill ~ the art that numerous variations ~n form and detail .,a~ be made tJithout dep~rting from the spirit and scope c the invention, as set forth in the following claims.

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Claims (4)

18

1. Apparatus for stacking a plurality of flat articles on edge, said apparatus comprising:
a discharge magazine for sequentially receiving and stacking said flat articles in a stack;
said discharge magazine including moveable discharge support means adapted to support said stack of articles on edge and moveable compression plate means to maintain said articles on edge;
drive means for controllably moving said discharge support means;
a stacker section adjacent said discharge magazine for transporting articles sequentially into said stack, said stacker section comprising a stacker support assembly and stacker belt means extending around a plurality of roller means supported by the support assembly;
the last of said articles in said stack abutting against said stacker belt means adjacent one of said roller means to apply a compressive force developed by said stack of flat articles and said compression plate to said one roller means;
said one roller means movably mounted to said stacker support assembly for movement responsive to increases and decreases in said compressive force;
actuator means operatively connected to and responsive to movement of said one roller means and connected to said drive means for activating said drive means and said discharge support means to transport said stack of flat articles away from said stacker section when said compressive force reaches a predetermined maximum value; and the stacker section comprising deflection means proximate the stack of articles for preventing a leaning surface of a stacked article from applying said predetermined maximum value to said roller means, said deflection means comprising a member with an outer deflection surface, said deflection surface facing outwardly toward said stack of articles and extending outwardly to a distance substantially coincident with an abutment surface of said stacker belt means when said compressive force reaches said predetermined maximum value, said deflection means further being moveable to vary the distance over which said deflection surface may extend.

2. The apparatus of claim 1 wherein said member is a plate having at least a portion located in a plane substantially parallel with a portion of a base plate in the stacker support assembly.

3. The apparatus of claim 2 wherein said plate is vertically adjustable about a support member which extends perpendicular to said plate.

4. The apparatus of claim 1 wherein the position of the deflection means is adjustable.