Apparatus for separating and feeding sheets from a stack thereof

Apparatus for feeding respective sheets from a stack thereof comprising structure for supporting a plurality of sheets in an upright stack thereof, the supporting structure including an upright wall, the supporting structure including a deck extending beneath the wall and defining a path of travel for respective sheets fed from the stack, the deck extending transverse to the path of travel; structure for successively feeding respective sheets downstream in the path of travel, the feeding structure including opposed outfeed rollers downstream of the upright wall, the feeding structure including an elongate first roller longitudinally extending transverse to the path of travel upstream of the upright wall, the feeding structure including an elongate second roller longitudinally extending transverse to the path of travel upstream of the fist roller, the feeding structure including structure for driving the outfeed and first and second rollers; structure for controlling the driving structure, and the controlling structure including structure for causing the driving structure to continuously drive at least one of the outfeed rollers and to selectively drive the first and second rollers.

BACKGROUND OF THE INVENTION 
This invention is generally concerned with apparatus for feeding sheets 
from a stack of sheets and, more particularly, for feeding respective 
sheets one at a time from the bottom of an upright stack of sheets on a 
deck, including means for compensating for variations in forces exerted on 
the respective sheets by the stack and deck as the respective sheets are 
fed from the stack. 
U.S. Pat. No. 3,977,668 for DUAL PURPOSE SHEET MATERIAL FEEDING AND SAFETY 
APATUS, issued Aug. 31, 1976 to Bologna, et al. and assigned to the 
assignee of the present invention, discloses an upright stack of sheets 
which is supported on a feed deck inclined at an angle relative to an 
upright wall for urging an edge of each of the sheets into registration 
with the wall. In addition, there is disclosed opposed output feed rollers 
situated at the junction between the deck and wall for feeding respective 
sheets one at a time from the bottom of the stack. 
U.S. Pat. No. 4,973,037 for a FRONT END FEEDER FOR MAIL HANDLING MACHINE, 
issued Nov. 27, 1990 to Holbrook and assigned to the assignee of the 
present invention, discloses sheet feeding apparatus comparable to the 
apparatus shown in the aforesaid '668 patent, for use in a high speed 
machine for handling mixed mail pieces, wherein a drive assembly is 
provided for feeding successive mailpieces from the bottom of the stack of 
sheets while maintaining the mailpieces in registration with a fence and 
fluffing the stack to promote separation of the respective mailpieces from 
one and other. 
When the aforesaid sheet feeding apparatus and like structures are utilized 
for separating large envelopes or other sheets, the individual sheets may 
weigh so much that the frictional forces exerted by the stack and deck 
against the drive forces exerted by the feed rollers are such that the 
respective sheets either cannot be fed from the stack or are misfed 
therefrom. This ordinarily occurs in due to the forces exerted by the feed 
rollers being insufficient to overcome the static frictional forces 
exerted by the deck and stack on the lowermost sheet of the stack, or, as 
a given sheet is exiting the stack, due to the normal force exerted by the 
stack on the given sheet being insufficient to permit the opposed outfeed 
roller to frictionally engage and feed the sheet from beneath the stack. 
In any event, any given sheet being fed from the bottom of a stack is 
subjected to a wide range of normal forces in the course of being fed 
therefrom. Accordingly, 
an object of the invention is to provide an apparatus for feeding 
respective sheets from a stack thereof including means for compensating 
for variations in forces exerted on the respective sheets in the course of 
feeding the same; 
another object is to provide such compensating means including a 
microcomputer programmed for intermittently driving respective rollers 
engaging the lowermost sheet of the stack to ensure separation of the 
sheets and feeding the sheets from the stack; and 
another object is to provide structure for controlling a plurality of sheet 
feeding rollers, engaging successive lowermost sheets of the stack, in 
consideration of the length of such sheets in the direction of feeding. 
SUMMARY OF THE INVENTION 
Apparatus for feeding respective sheets from a stack thereof comprising 
means for supporting a plurality of sheets in an upright stack thereof, 
the supporting means including an upright wall, the supporting means 
including a deck extending beneath the wall and defining a path of travel 
for respective sheets fed from the stack, the deck extending transverse to 
the path of travel; means for successively feeding respective sheets 
downstream in the path of travel, the feeding means including opposed 
outfeed rollers downstream of the upright wall, the feeding means 
including an elongate first roller longitudinally extending transverse to 
the path of travel upstream of the upright wall, the feeding means 
including an elongate second roller longitudinally extending transverse to 
the path of travel upstream of the first roller, the feeding means 
including means for driving the outfeed and first and second rollers; 
means for controlling the driving means, and the controlling means 
including means for causing the driving means to continuously drive at 
least one of the outfeed rollers and to selectively drive the first and 
second rollers.

DESCRIPTION OF THE PREFERRED EMBODIMENTS 
As shown in FIG. 1, according to the invention there is provided apparatus 
10 for feeding respective sheets 12 from a stack 14 of sheets 12, 
including conventional framework 11 for supporting the various components 
of the apparatus 10. The sheet feeding apparatus 10 includes structure 16 
for supporting a plurality of the sheets 12 in an upright stack 14, 
including a substantially vertically extending upright wall 18. In 
addition, the supporting structure 16 includes a deck 20 which extends 
beneath the wall 18 and thus defines a path of travel 22 extending 
therebeneath in which respective sheets 12 are fed from the stack 14. The 
deck 20 is preferably inclined upwardly from the downstream end 21a 
thereof to the upstream end 21b thereof, for urging the respective sheets 
12 of the stack 14 into edge registration with the upright wall 18. And, 
as shown in FIG. 2, the deck 20 extends transverse to the path of travel 
22 of respective sheets 12 fed from the stack 14. Moreover, the deck 20 
preferably includes three portions thereof defining the path of travel 22, 
that is, an upstream portion 24 and a downstream portion 26, and a middle 
portion 28 between the upstream portion 24 and the downstream portion 26 
which is spaced apart therefrom. 
In addition, the sheet feeding apparatus 10 (FIG. 1) includes structure 40 
for successively feeding respective sheets 12 downstream in the path of 
travel 22. Thus, each of the sheets 12 in the path of travel 22 has a 
leading edge 12a and a trailing edge 12b, and has a predetermined overall 
length "L" as measured in the path of travel 22 from the leading edge 12a 
to trailing edge 12b thereof. The feeding structure 40 also preferably 
includes a pair of opposed upper and lower outfeed rollers, respectively 
designated 44 and 45. The outfeed rollers 44, 45, are each elongate 
rollers which are conventionally coaxially mounted on drive shafts 44a 
(FIG. 2) and 45a. The drive shafts, 44a (FIG. 2) and 45a, are respectively 
suitably journaled to the framework 11 for rotation, so that the 
respective rollers, 44 and 45, longitudinally extend transverse to the 
path of travel 22, downstream from the upright wall 18, for engaging and 
feeding sheets 12 fed therebetween from the stack 14. Further, the feeding 
structure 40 additionally preferably includes a pair of opposed upper and 
lower take-away rollers, respectively designated 46 and 47. The take-away 
rollers, 46, 47, are each elongate rollers which are conventionally 
coaxially mounted on drive shafts 46a and 47a. The drive shafts, 46a and 
47a, are respectively suitably journaled to the framework 11 for rotation, 
so that the respective rollers, 46 and 47, longitudinally extend 
transverse to the path of travel 22, downstream from the outfeed rollers, 
44 and 45, for engaging and feeding sheets 12 fed thereby between the 
take-away rollers, 46 and 47. Moreover, the feeding structure 40 includes 
an elongate, first, pre-feed, roller 48, which is conventionally coaxially 
mounted on a drive shaft 48a. The drive shaft 48a is suitably journaled to 
the framework 11 for rotation, so that the roller 48 longitudinally 
extends transverse to the path of travel 22, upstream of the upright wall 
18 and between the downstream deck portion 26 and middle deck portion 28. 
Further, the feeding structure 40 includes an elongate, second, pre-feed 
roller 50, which is conventionally coaxially mounted on a drive shaft 50a. 
And the drive shaft 50a is suitably journaled to the framework 11 for 
rotation so that the roller 50 longitudinally extends transverse to the 
path of travel 22, upstream from the upright wall 18 and between the 
middle deck portion 28 and upstream deck portion 24. 
For driving the outfeed rollers, 44, 45 (FIG. 1), take-away rollers, 46, 
47, and pre-feed rollers 48, 50, the sheet feeding structure 40 preferably 
includes structure 64 (FIG. 2) for driving at least one of each of the 
pairs of rollers, 44, 45, and 46, 47, and for driving each of the rollers, 
48 and 50. The driving structure 64 preferably includes a first 
electro-magnetic clutch system 66, including a first clutch 68, having a 
first portion 68a and a second portion 68b, and including a first drive 
gear 70. The clutch portion 68a is conventionally mechanically connected 
to the first roller drive shaft 48a, and the second clutch portion 68b is 
conventionally mechanically connected to the first drive gear 70. 
Moreover, the clutch 68 is conventionally constructed and arranged to be 
electrically operable for magnetically connecting the first and second 
clutch portions, 68a and 68b, to one another for connecting the first 
drive gear 70 to the first roller drive shaft 48a, to permit the first 
roller 48 to be driven by the gear 70, and for disconnecting the first and 
second clutch portions, 68a and 68b, from one another for disconnecting 
the first drive gear 70 from the first roller drive shaft 48a, to prevent 
the first roller 48 from being driven by the gear 70. Preferably, the 
driving structure 64 additionally includes a second electro-magnetic 
clutch system 76, including a second clutch 78, having a first portion 78a 
and a second portion 78b, and including a second drive gear 80. The clutch 
portion 78a is conventionally mechanically connected the second roller 
drive shaft 50a, and the second clutch portion 78b is conventionally 
mechanically connected to the second drive gear 80. Moreover, the clutch 
78 is conventionally constructed and arranged to be electrically operable 
for magnetically connecting the first and second clutch portions, 78a and 
78b, to one another for connecting the second drive gear 80 to the second 
roller drive shaft 50a, to permit the second roller 50 to be driven by the 
gear 80, and for disconnecting first and second clutch portion, 78a and 
78b, from one another for disconnecting the second drive gear 80 from the 
second roller drive shaft 50a, to prevent the second roller 50 from being 
driven by the gear 80. Further, the driving structure 64 also preferably 
includes third, fourth and fifth drive gears 82, 82a and 83. Preferably 
the drive gears 82 and 82a are conventionally fixedly connected to the 
lower outfeed drive shaft 45a, and the drive gear 83 is conventionally 
fixedly connected to the lower take-away roller drive shaft 47a, for 
driving the lower outfeed and take-away rollers 45 and 47. Moreover, the 
driving structure 64 includes a conventional d.c. motor 84 which includes 
an output drive shaft 86, and includes first and second pinion gears, 
respectively designated 88 and 90. The pinion gears, 88, 90, are spaced 
apart from one another and respectively suitably, fixedly, connected to 
the d.c. motor output drive shaft 86 for driving thereby. In addition, the 
driving structure 64 includes a first gear belt 92, which is looped about 
the first pinion gear 88 and about the respective clutch system drive 
gears, 70 and 80, and is disposed in meshing engagement therewith for 
transmitting motive power from the d.c. motor 84 to the pre-feed rollers, 
48, 50. The driving structure 64 also includes a second gear belt 94 which 
is looped about the second pinion gear 90 and about the lower outfeed 
roller drive gear 82, and is disposed in meshing engagement therewith for 
transmitting motive power from the d.c. motor 84 to the outfeed roller 45. 
And, the driving structure includes a third gear belt 95 which is looped 
about the drive gear 82a and about the lower take-away roller drive gear 
83, and is disposed in meshing engagement therewith for transmitting 
motive power from the lower output roller drive shaft 45a to the lower 
take-away roller drive shaft 47a and thus to the take-away roller 47. 
The apparatus 10 (FIG. 2) additionally includes structure 100 for 
controlling the driving structure 64. The controlling structure 100 
includes a microcomputer 102, which is preferably any commercially 
available microprocessor having sufficient capacity to store the programs 
and other data, and to implement the counting, timing, calculating and 
other functions, hereinafter discussed. In addition, the controlling 
structure 100 includes a plurality of power amplifiers, including first, 
second and third power amplifiers respectively designated 104, 106, and 
108. Further, the controlling structure 100 includes structure 110 for 
sensing sheets 12 fed from the stack 14 (FIG. 1). And, the controlling 
structure 100 (FIG. 2) includes structure 112 for providing counts 
corresponding to the overall length "L" (FIG. 1) of respective sheets 12, 
and increments of the respective lengths "L" thereof, in the path of 
travel 22. The power amplifiers 104 (FIG. 2), 106 and 108, sensing 
structure 110 and counting structure 112 are preferably any commercially 
available components of their respective types which are suitable for 
implementing the respective functions hereinafter ascribed thereto. 
The first power amplifier 104 (FIG. 2) is conventionally electrically 
connected between the microcomputer 102 and first clutch 68 for providing 
signals thereto, such as the signal 114, for operation of the first clutch 
68 under the control of the microcomputer 102. The second power amplifier 
106 is conventionally connected between the microcomputer 102 and second 
clutch 78 for providing signals thereto, such as the signal 116, for 
operation of the second clutch 78 under the control of the microcomputer 
102. The third power amplifier 108 is conventionally electrically 
connected between the microcomputer 102 and d.c. motor 84 for providing 
signals thereto, such as the signal 118, for operation of the d.c. motor 
84 under the control of the microcomputer 102. The microcomputer 102 is 
conventionally electrically connected to the sensing structure 110 for 
receiving successive signals, such as the signal 120, therefrom in 
response to the sensing structure 110 sequentially sensing the leading and 
trailing edges, 12a (FIG. 1) and 12b, of respective sheets 12 fed thereto 
and therefrom. The counting structure 112 (FIG. 2) is conventionally 
mechanically connected to the d.c. motor drive shaft 86 for operation 
thereby. And, the microcomputer 102 is conventionally electrically 
connected to the counting structure 112 for receiving sequential signals, 
such as the signal 122, therefrom in response to the counting structure 
112 sensing sequential increments of angular displacement of the motor 
drive shaft 86. The controlling structure 100 also includes a conventional 
keyboard 124, including a manually operable, first, switching, key 126 
which is preferably a depressible test key, and including a manually 
operable, second, switching, key 128, which is preferably a depressible 
on-line key. Optionally, the keyboard 124 may also include a plurality of 
manually operable, third, switching, keys 129, each of which is preferably 
a sheet-length selection key 129, representative of the overall length "L" 
of a different commercially available sheet 12. The keyboard 124 is 
suitably electrically connected to the microcomputer 102 for providing 
signals thereto, such as the signal 130, in response to manual depression 
of the test and on-line keys, 126, 128, and, assuming provision of the 
sheet-length keys 129, in response to manual depression of each of the 
sheet-length keys 129. Moreover, the apparatus 10 includes a conventional 
d.c. power supply 134, and includes a conventional power switch 136 which 
is suitably electrically connected to the d.c. power supply 134 and 
adapted to be conventionally connected to an external source of supply of 
a.c. power 138 for a.c. energization and deenergization of the d.c. power 
supply 134 in response to manual operation of the switch 136. And, the 
d.c. power supply 134 is suitably electrically connected to the 
microcomputer 102, power amplifiers 104, 106 and 108, d.c. motor 84 and 
keyboard 124, for d.c. energization, B+, thereof in response to a.c. 
energization of the d.c. power supply 134. 
As shown in FIG. 3, the microcomputer 102 generally comprises a plurality 
of discrete circuits, including those for a central processing unit, 
including a plurality of control circuits "A", a program counter "B", a 
plurality of working registers "C" and an arithmetic logic unit "D", and 
those for an oscillator and clock "E", data memory "F", timer and event 
counters "G" and program expansion control "H". Further, the microcomputer 
102 comprises a plurality of additional discrete circuits including those 
for a plurality of program memories, including a main line program memory 
"I". Moreover, the microcomputer 102 preferably includes a plurality of 
spare registers "J" for future use as working registers or for future 
programming. And, the microcomputer 102 includes a plurality of serial and 
other programmable ports "K" which are conventionally interconnected as 
hereinbefore discussed to the d.c. motor 84, power amplifiers 104, 106 and 
108, sensing structure 110, and counting structure 112, and to the 
keyboard 124 for communication therewith. 
As shown in FIG. 1, the weight of the stack 14 on the pre-feed rollers, 48 
and 50, exerts vertically oriented forces F1 and F2 against the respective 
pre-feed rollers, 48 and 50, whether or not sheets 12 are being fed from 
the stack 14. Assuming actuation of the on-line key 130 (FIG. 2), with the 
result that sheet feeding is commenced, then, as a given lowermost sheet 
12 (FIG. 1) is initially being fed from the stack 14 by the pre-feed 
rollers, 48, 50, the stack 14 exerts an upstream directed frictional force 
F.sub.3 against the upper surface 12c of the lowermost sheet 12, and, in 
addition, the deck 20 exerts an upstream directed frictional force F.sub.4 
against the lower surface 12d of the lowermost sheet 12. Moreover, the 
upstream directed frictional forces F.sub.3 and F.sub.4 are exerted 
against downstream directed forces F.sub.5 and F.sub.6 exerted by the 
respective first and second pre-feed rollers, 48, 50, against the 
lowermost sheet 12. Thereafter, as the lowermost sheet 12 is fed to and 
between the outfeed rollers, 44, 45, the outfeed rollers, 44, 45, engage 
and feed the lowermost sheet 12, thereby adding to the pre-feed roller 
forces, F.sub.5 and F.sub.6, an additional downstream directed outfeed 
roller force F.sub.7. As sheet feeding continues, the sheet sensing 
structure 110 senses passage of the leading edge 12a of the lowermost 
sheet 12, and, the upstream directed frictional forces, F.sub.3 and 
F.sub.4, are continually reduced as a shorter and shorter portion of the 
overall length "L" of the lowermost sheet 12 is disposed in engagement 
with a stack 12 and deck 20. Eventually, the trailing edge 12b of the 
lowermost sheet 12 disengages the second pre-feed roller 50. Whereupon, 
according to the invention, drive to the second pre-feed roller 50 is 
stopped to prevent the second pre-feed roller 50 from feeding the sheet 12 
next to the lowermost sheet 12 from the stack 14 and into overlapping 
relationship with the lowermost sheet 12 being fed from the stack 14. As 
sheet feeding further continues, the outfeed rollers 44, 45, and first 
pre-feed roller 48, but not the second pre-feed roller 50, feed the 
lowermost sheet 12 from the stack 14, against the diminished upstream 
directed frictional forces, F.sub.3 and F.sub.4, exerted by the stack 14 
and deck 20. And, according to the invention, when such sheet feeding 
results in the trailing edge 12b of the lowermost sheet 12 disengaging the 
first pre-feed roller 48, drive to the first pre-feed roller 48 is also 
stopped, to prevent the first pre-feed roller 48 from feeding the sheet 12 
next to the lowermost sheet 12 from the stack 14 and into overlapping 
relationship with the lowermost sheet 12. Thereafter, as sheet feeding 
still further continues, the outfeed rollers, 44, 45, but not the first or 
second pre-feed rollers, 48 or 50, feed the lowermost sheet 12 from the 
stack 14 against the greatly reduced upstream directed frictional forces, 
F.sub.3 and F.sub.4, exerted by the stack 14 and deck 20 on the lowermost 
sheet 12. According to the invention, as sheet feeding continues, as above 
discussed, the lowermost sheet 12 is fed downstream from the stack 12 to 
the take-away rollers, 46, 47, which, without departing from the spirit 
and scope of the invention, may be augmented or replaced by any 
conventional structure 150, externally of the apparatus 10, such as any 
suitable printing, folding, inserting or other sheet processing structure 
which is equipped for receiving and feeding the lowermost sheet 12 either 
away from the apparatus 10, in the case of augmentation of the take-away 
rollers, 46, 47, or away from the sensing structure 100 and thus away from 
the apparatus 10, in the case of replacement of the take-away rollers, 46, 
47. In any event, as the lowermost sheet 12 is fed away from the outfeed 
rollers 44, 45, the sensing structure 110 senses passage of the trailing 
edge 12b of the moving sheet 12. According to the invention, after a 
predetermined time delay "td" from the sensing structure 110 sensing the 
trailing edge 12b of a sheet 12, fed from the stack 14 the feeding 
structure 64 commences feeding the next lowermost sheet 12 from the stack 
14, and so on, until the stack 14 of sheets 12 is depleted. 
For implementation of the invention, the microcomputer 102 (FIG. 3), is 
conventionally programmed for storing in the data memory "F", data in the 
form of predetermined first and second counts corresponding, respectively, 
to the distance d.sub.1 between the first pre-feed roller's outer 
periphery 48b and the sensing structure 110, and the distance d.sub.2 
between the second pre-feed roller's outer periphery 50b and the sensing 
structure 110, as measured along the path of travel 22. And, it is noted 
that each of such counts corresponds to increments of the distances 
d.sub.1 and d.sub.2 which are equivalent to the increments of length "L", 
hereinafter discussed, which are counted by the microcomputer 102 in 
response to signals 122 received thereby from the counting structure 112. 
For determining the overall length "L" of the respective sheets 12 of a 
stack 14 thereof which is to be fed from the sheet supporting structure 
16, a given, representative, sheet 12 having the length "L" of each of the 
sheets 12 of the stack 14 is placed on the deck 20 with the leading edge 
12a thereof disposed in the nip between the outfeed rollers, 44, 45, for 
feeding thereby downstream in the path of travel 22, and, the test key 126 
is manually depressed. 
The microcomputer 102 (FIG. 3) has stored in the main line program 
circuitry "I", programming for causing the microcomputer 102 to 
selectively energize the first and second clutches, 68 and 78, for 
connecting the drive gears, 70, 80, to the pre-feed roller drive shafts, 
48a, 50a, and to commence energization of the d.c. motor 84 to selectively 
drive the outfeed, take-away and pre-feed rollers 44, 45, 46, 47, 48 and 
50, in response to the microcomputer 102 receiving a signal 130 indicating 
that the test key 126 has been actuated. Accordingly, when the test key 
126 is depressed, the rollers 44, 45, 48 and 50 feed the given sheet 12 
downstream in the path of travel 22 to the sensing structure 110, which 
sequentially senses passage of the leading and trailing edges 12a and 12b 
of the given sheet 12 and provides sequential signals 130 indicative 
thereof to the microcomputer 102. In addition, the counting structure 112, 
which is preferably a conventional motor drive shaft encoder, sequentially 
senses angular displacements of the motor drive shaft 86 corresponding to 
equal increments of the length "L" of respective sheets 12 fed downstream 
in the path of travel 22. And, the microcomputer's main line program 
circuitry "I" is programmed to cause the microcomputer 102 to commence a 
third count of the sequential signals 122 received from the shaft encoder 
112 in response to the microcomputer 102 receiving the first signal 130 
from the sensing structure 110, indicating that the leading edge 12a of 
the sheet 12 has been sensed, and to end the third count in response to 
the microcomputer 102 receiving the second signal 130 from the sensing 
structure 110, indicating that the trailing edge 12b of the sheet 12 has 
been sensed. Moreover, the microcomputer circuitry "I" is programmed to 
cause the aforesaid third count, which corresponds to the overall length 
"L" of the given sheet 12, to be stored in the data memory "F". In 
addition, the main line program circuitry "I" includes programming for 
causing the microcomputer 102 to conventionally compare the third count to 
the second count, as by calculating the difference therebetween, to 
determine if the third count is greater or less than the second count. 
Further, the aforesaid programming causes the microcomputer 102 to store a 
fourth count corresponding to the difference therebetween in the data 
memory "F" if the third count is greater, it being noted that the fourth, 
difference, count corresponds to the portion of the length "L" of the 
given sheet 12 which extends upstream of the second pre-feed roller's 
outer periphery 50a. On the other hand, if the aforesaid comparison 
indicates that the third count is less than the second count, then, the 
aforesaid programmed circuitry "I" causes the microcomputer 102 to store a 
fifth count corresponding to the difference between the sheet length "L" 
and the distance "d.sub.1 " between the first pre-feed roller's outer 
periphery 48b and the sensing structure 110, in the data memory "F", it 
being noted that the fifth, difference, count corresponds to the portion 
of the overall length "L" of the given sheet 12 which extends upstream of 
the first pre-feed roller's outer periphery 48a. 
Assuming as hereinbefore discussed that the keyboard 124 includes the 
optional, sheet-length selection, keys 129, then, the test key 126 does 
not have to be depressed, nor for that matter be provided, for causing a 
representative sheet 12 to be fed from the sheet supporting structure 16. 
Further, the microcomputer 102 need not be programmed as hereinbefore 
discussed for sensing the sheet's leading and trailing edges, 12a and 12b, 
to establish the third count representative of the overall length "L" of a 
given sheet 12. Rather, the operator may select a key 129 corresponding to 
the length "L" of a given, representative, sheet 12, as by depressing that 
key 129, for providing a signal 130 to the microcomputer 102 corresponding 
to the predetermined sheet length "L". And, the microprocessor 102 may be 
programmed for providing a sixth count corresponding the selected overall 
length "L" of the representative sheet 12 in response to the sheet length 
selection key signal 130. Thereafter, the microcomputer 102 may implement 
the remainder of the aforesaid programming by comparing the sixth count, 
rather than the third count, to the second count. However, notwithstanding 
the foregoing discussion, all of the aforesaid programming is preferably 
provided to ensure that the overall length "L" of any sheet 12, whether or 
not a sheet-length selection key 129 is provided therefor, may be 
established through implementation of such programming. 
Assuming implementation of the foregoing programming, and that a stack 14 
(FIG. 1) of sheets 12, corresponding to the representative sheet 12 is 
loaded into the supporting structure 12, then, the on-line key 128 may be 
manually depressed to cause the apparatus 10 to sequentially feed each 
successive lowermost sheet 12 from the stack 12, as hereinbefore 
discussed. To that end, the microcomputer 102 circuitry "I" (FIG. 3) is 
programmed for causing the microcomputer 102 to energize both of the first 
and second clutches, 68 and 78, if the given sheet length "L" is greater 
than the distance d.sub.2 between the second pre-feed roller's periphery 
50b, as measured along the path of travel 22, for connecting the drive 
gears, 70, 80, to the pre-feed roller drive shafts, 48a, 50a, and to 
commence energization of the d.c. motor 84 to drive the outfeed, take-away 
and both of the pre-feed rollers 44, 45, 46, 47, 48 and 50, in response to 
the microcomputer 102 receiving a signal 130 indicating that the on-line 
key 128 has been actuated. 0n the other hand, if the given sheet length 
"L" is less than the distance d.sub.2 between second pre-feed roller's 
outer periphery 50b, as measured along the path of travel 22, then, the 
programming causes the microcomputer 102 to energize the first clutch 68, 
but not the second clutch 78 for connecting the drive gear 70 to the 
pre-feed rollers drive shaft 48a and to commence energization of the d.c. 
motor 84 to drive the outfeed, take-away and first pre-feed roller 44, 45, 
46, 47 and 48, but not the second pre-feed roller 50. Accordingly, when 
the on-line key 128 is depressed, the rollers 44, 45 and 48 alone or in 
combination with the roller 50, feed a given, lowermost, sheet 12 
downstream in the path of travel 22 to the sensing structure 110, which 
senses passage of the leading edge 12a of the lowermost sheet 12 and 
provides a signal 130 indicative thereof to the microcomputer 102. In 
response to the signal 130, the programming of the microcomputer 102 
commences a seventh count of sequential encoding signals 114 received by 
the microcomputer 102. Assuming the sheet length "L" is greater than the 
distance "d.sub.2 " then when the seventh count is equal to the fourth 
count, i.e., corresponding to the difference between the sheet length "L" 
and the distance "d.sub.2 ", the microcomputer programming causes the 
second clutch 78 to be deenergized for disconnecting the drive gear 80 
from the roller drive shaft 50a to cause the second pre-feed roller 50 to 
stop being driven by the d.c. motor 84. And, thereafter, or if the moving 
sheet length "L" is less than the distance d.sub.2, when the seventh count 
is equal to the fifth count, i.e., corresponding to the difference between 
the sheet length "L" and the distance "d.sub.1 " between the first 
pre-feed roller's outer periphery 48b and the sensing structure 110, as 
measured along the path of travel 22, the microcomputer programming causes 
the first clutch 68 to be operated for disconnecting the drive gear 70 
from the first roller's drive shaft 48a to cause the first pre-feed roller 
48 to stop being driven by the d.c. motor 84. Thereafter, independently of 
the length "L" of the sheet 12 being fed, when the sheet's trailing edge 
12b is sensed by the sensing structure 110 the programming causes the 
microcomputer 102 to commence an eighth count of a predetermined time 
delay "td" before the next lowermost sheet 12 is fed from the stack 14, as 
a result of which the trailing and leading edges, 21b and 21a, of 
successive sheets 12 fed from the stack 14 are separated from one another 
by a predetermined distance corresponding to the count of the 
predetermined time delay "td". 
As shown in FIG. 4, the main line program 200, which is stored in the 
circuits of the main line program memory "I" (FIG. 3), commences with the 
step 202 (FIG. 4) of conventionally initializing the microcomputer 100 
(FIG. 2), which generally includes establishing the initial voltage levels 
at the programmable ports K (FIG. 3) setting the timer and event counters 
"G" and, if necessary, initializing the d.c. motor 84, for example, as by 
scanning the microcomputer ports "K" associated with the d.c. motor 86 and 
determining whether or not one or more selected elements of the d.c. motor 
86 are properly located for initiating operation thereof, and, if not, 
causing the d.c. motor 84 to be driven to its home position, if any. 
Assuming the initialization step 202 (FIG. 4) is completed, the main line 
program 200 enters into an idle loop routine 204. In the idle loop 
routine, step 204, the program 200 implements the step 206 of initially 
determining whether or not any of the keyboard keys 126, (FIG. 2), 128 or 
129, have been actuated and, if not, the program 200 (FIG. 4) continuously 
loops through step 206 until one of such keys 126, 128 or 129 have been 
actuated. Whereupon, the program 200 causes the microcomputer 102 to scan 
the programmable ports "K" (FIG. 3) thereof, to determine which of the 
keys 126 (FIG. 2), 128 or 129 has been actuated. Assuming that a plurality 
of selection keys 129 have been provided, a test key 126 has not been 
provided, and one of the sheet length selection keys 129 has been 
actuated, step 208 (FIG. 4), then, the program 200 implements the step 210 
of storing the count corresponding to the selected sheet length key 129 
(FIG. 2), which count corresponds to a predetermined length "L" of the 
respective sheets 12 a stack of sheets 12 which are to be fed from the 
apparatus 10. Thereafter, the program 200 causes processing to be returned 
to step 206. Assuming that the sheet length selection keys 129 (FIG. 2) 
are not provided, that a test key 126 is provided, and that the test key 
124 has been actuated, step 212 (FIG. 4), then, the program 200 causes the 
microcomputer 102 (FIG. 2) to implement the step 214 of energizing both of 
the first and second clutches, 68 and 78, and the d.c. motor 84, for 
causing the rollers 45, 46, 47, 48 and 50 to feed a sheet 12 through the 
apparatus 10. Thereafter, the program 200 (FIG. 4) implements the step 216 
of causing the microcomputer 102 to determine whether or not the sensing 
structure 110 (FIG. 2) has sensed the leading edge 12a of a sheet 12 being 
fed through the apparatus 10. Assuming that the leading edge 12a has not 
been sensed, step 216 (FIG. 4), then, the program 200 continuously loops 
through step 216 until the leading edge 12a is sensed. Whereupon, the 
programming causes the microcomputer 102 to implement the step 210 of 
starting a count of the encoder signals 122 received by the microcomputer 
102, followed by the step 220 of the determining whether or not the 
trailing edge 21b (FIG. 2) of the sheet 12 has been sensed by the sensing 
structure 110. Assuming that the trailing edge 12b is not sensed, then, 
the program 200 (FIG. 4) continuously loops through step 220 until the 
trailing edge 12b is sensed. Whereupon, the program 200 causes the 
microcomputer 102 to implement the step 222 of stopping the count started 
in step 218, followed by the step 224 of storing the count of step 222 in 
the data memory "F" (FIG. 3). Thereafter, the program 200 (FIG. 4) returns 
processing to step 206. Accordingly, operation of the test key, step 212, 
results in storing a count corresponding to the overall length "L", step 
224, of the sheet 12 which is fed through the apparatus 10. Assuming that 
both the test key 126 (FIG. 2) and the sheet length selection keys 129 are 
provided, then, if the test key 126 is not actuated step 212 (FIG. 4), and 
it is assumed that a sheet length selection key 129 is actuated, step 226, 
then, the program 200 causes implementation of the step 228 of causing the 
storage of a count corresponding to the selected sheet length selection 
key 129 (FIG. 2), which count corresponds to the length "L" of a sheet 12 
of a stack of sheets 14 which is to be fed through the apparatus 10. 
Assuming completion of implementation of the aforesaid program steps (FIG. 
4), commencing with either step 208, or step 212 alone or in combination 
with step 226, and the return of processing to step 206, then, in any 
event, a sheet length "L" corresponding to the length of a representative 
sheet 12 (FIG.2) of a stack of sheets 12 which is to be fed by the 
apparatus 10 is stored in the microcomputer 102. In addition, it will be 
assumed that the stack 14 is appropriately loaded into the supporting 
structure 16. 
Returning then to FIG. 4, and assuming that a determination has been made 
in step 240 that it is the on-line key, 128, which has been actuated, 
then, the program 200 (FIG. 4) causes the microcomputer 102 to implement 
the step 242 of determining whether or not the sheet length "L" is greater 
than the distance "d.sub.2 " (FIG. 1) between the second pre-feed 
roller's, outer periphery 50b and the sensing structure 110. Assuming that 
it is, step 242, the program 200 causes implementation of the step 244 of 
energizing both of the clutches 68 (FIG. 2) and 78, and, if not already 
energized, the d.c. motor 84. Thereafter, the program 200 (FIG. 4) causes 
implementation of the step 246 of determining whether or not the leading 
edge 12a (FIG. 1) of a lowermost sheet of 12 of the stack 14 is sensed by 
the sensing structure 100. Assuming that it is not, the program 200 (FIG. 
4) causes processing to continuously loop through step 246 until the 
leading edge 12a of a sheet 12 is sensed. Whereupon, the program 200 
causes implementation of the step 248 of starting a count of the encoder 
signals 122 received by the microcomputer 102, followed by the step 250 of 
determining whether or not the count corresponds to the count difference 
between the count corresponding to the stored length "L" of a sheet 12 and 
the count corresponding to the distance d.sub.2 between the outer 
periphery 50b of the second pre-feed roller 50 and the sensing structure 
100. Assuming that it is not, step 250, then, the program 200 continuously 
loops through step 250 until it is. Whereupon, the program 200 causes 
implementation of the step 252 of deenergizing the second pre-feed roller 
clutch 78 to cause the second pre-feed roller 50 to stop feeding. 
Returning to step 242, it is noted that if the inquiry thereof is 
negative, i.e., the sheet length "L" is not greater than the distance 
d.sub.2 between the second pre-feed roller's outer periphery 50b and the 
sensing structure 110, then, the program 200 implements the step 260 of 
energizing the first 68, but not the second 78 pre-feed roller clutch, 
and, if it is not already energized, the d.c. motor 84. Accordingly, step 
260 results in causing all of the rollers 44 (FIG. 2), 45, 46, 47 and 48 
but not the roller 50 to be driven from the d.c. motor 84. Thereafter, the 
program 200 (FIG. 4) causes implementation of the step 262 of determining 
whether or not the sheet's leading edge 12a has been sensed and, assuming 
that it has not, step 262, processing is looped through step 262 until the 
sheet's leading edge 12a is sensed. Whereupon, the program 200 causes 
implementation of the step 264 of starting a count of the encoder signals 
122 received by the microcomputer 102, step 264, which step 264 
corresponds in all respects to step 248. Following steps 252 or 264, the 
program 200 causes the microcomputer, d.sub.2 to then implement the step 
266 of determining whether or not the count started in either of steps 248 
or 264 corresponds to a count which is equal to the difference between the 
counts corresponding to the sheet length "L" and the distance "d.sub.1 " 
between the first pre-feed roller's outer periphery 48b and the sensing 
structure 100. Assuming that it is not, programming continuously loops 
through step 266 until it is. Whereupon, the program 200 causes the 
microcomputer 102 to implement the step 268 of deenergizing the first 
pre-feed roller's clutch 68 which results in the first pre-feed roller 48 
being disconnected from drive by the d.c. motor 84. Thereafter, the 
program 200 causes implementation of the step 270 of determining whether 
or not the trailing edge 12b of the sheet 12 being fed from the apparatus 
10 has been sensed by the sensing structure 110. Assuming that it is not, 
step 270, then the microcomputer program 200 causes processing to 
continuously loop through step 270 until it is. Whereupon, the program 200 
causes implementation of the step of commencing a count of a predetermined 
time delay "td" which corresponds to a desired predetermined distance 
between the trailing edge 21b (FIG. 1) of a given lowermost sheet 12 which 
has been fed from the stack 14 and the leading edge 21a of the next 
lowermost sheet 12 which is to be fed from the stack 14. Thereafter, as 
shown in FIG. 4, processing is returned to step 206. However, it is noted 
that if the on-line key 128 (FIG. 2) has been depressed, according to the 
invention the depression of the on-line key 128 causes the key 128 to 
remain actuated until such time as it is again depressed, as a result of 
which the inquiry of step 206 (FIG. 4) will again be affirmatively 
answered. And, step 240 will again be implemented for processing the next 
lowermost sheet 12 of the stack 14 after the time delay "td", step 272. 
Accordingly, successive lowermost sheets 12 of the stack 14 will be 
sequentially fed therefrom until the stack 14 is depleted as until the 
on-line key 128, the, as shown in FIG. 4, processing will continuously 
loop through step 246 or step 262 after depletion of the stack 12 and 
until the on-line key 128 is depressed. As a result, the drive rollers 45, 
47, 48 alone or in combination with the drive roller 50, will be 
continuously driven on a result of implementation of one or the other of 
steps 244 or 260 until the on-line key 128 is again depressed. 
Without departing from the spirit and scope of the invention, the clutches 
68 and 78 may, respectively, be replaced by commercially available 
clutch-brakes, which would, in the context of the invention, be operated 
differently than hereinbefore discussed, due to such clutch-brakes have 
three modes of operation, i.e., one in which the clutch-brakes may be 
selectively energized for causing the respective rollers, 48, 50, to be 
driven by the d.c. motor 84, another in which the clutch-brakes may be 
selectively energized for braking movement of the respective rollers, 
48,50, and yet another wherein the clutch-brakes may be selectively 
energized for permitting the rollers, 48, 50, to free-wheel in response 
to, for example, inertial forces. The clutch-brakes would be operated 
differently in that in addition to being selectively energized for driving 
the rollers, 48, 50, from the d.c. motor 84, as hereinbefore discussed in 
connection with the discussion of the clutches, 68, 78, they would be 
selectively energized for braking motion of the respective rollers, 48, 
50, whenever such rollers, 48, 50, are not being driven. Moreover, without 
departing from the spirit and scope of the invention, the the counting 
structure 112 may be mounted on the lower outfeed roller drive shaft 45a 
rather than on the d.c. motor output drive shaft 86. And, the upper 
outfeed roller shaft 44a may be fixedly attached to the framework 11 to 
prevent rotation thereof, rather than being journaled thereto for 
rotation, to promote separation of the lowermost sheet 12 from any next 
lowermost sheet 12 inadvertently fed from the stack 14.