Sheet separator apparatus for recirculating feeder

A recirculating document feeder for a copier/duplicator removes sheets seriatim from the bottom of a stack of sheets, circulates a removed sheet to a position for copying, and then returns the sheet back onto the top of the stack of sheets. A sheet separator engages the sheet that initially is on top of the stack for separating the sheets in the stack that have been circulated along the path from those sheets in the stack that have not been circulated along the path. In response to feeding of the top sheet of the stack along the path, the separator is retracted and then returned to the top of the stack after the top sheet has been circulated for copying. The separator is driven along a generally rectilinear path and guided along that path by a pin in the separator that travels along a slot formed partially in each of two facing surfaces.

BACKGROUND OF THE INVENTION 
This invention relates to a sheet separator in a recirculating document 
feeder for a copier/duplicator and, more specifically, to improved 
apparatus for guiding and driving the separator through its path of 
travel. 
U.S. Pat. No. 4,076,408, issued Feb. 28, 1978, and U.S. Pat. No. 4,164,347, 
issued Aug. 14, 1979, disclose recirculating document feeders for a 
copier/duplicator wherein document sheets are fed seriatim along a path 
leading from the bottom of a stack of such sheets to a copying position 
and then back to the top of the stack of sheets. The recirculating feeders 
include a support for holding the stack of sheets and means for feeding 
the sheets along the path seriatim. A separator is engageable with the 
sheet that initially is on top of the stack for separating sheets in the 
stack that have been circulated along the path from those sheets in the 
stack that have not been circulated along the path. When the sheet that 
initially is on top of the stack reaches the bottom of the stack and is 
fed along the sheet path, the separator is returned to the top of the 
stack so that it again rests on the same sheet at the top of the stack of 
sheets. The sheet separator in such patents are driven in a rotary path 
about an axis. 
During rotation of the separator back to the top of the stack it actuates a 
switch which provides a signal to a logic and control unit (LCU) to 
indicate that the entire set of document sheets has been circulated to the 
exposure position once. The LCU counts the number of copy sets that have 
been made and compares that count to the number of such sets requested by 
the machine operator. 
While sheet separators and drives therefore of the type described in such 
patents have worked satisfactorily, the drive force applied to the 
separator also is applied to the document sheets. When only a few 
documents sheets are in the stack, the separator can cause damage to the 
sheets. 
U.S. Pat. No. 4,231,562, issued Nov. 4, 1980, discloses a recirculating 
document feeder with a sheet separator that is driven through a generally 
rectilinear guide path by a solenoid that applies a linear force to the 
separator. One problem with such apparatus is that it requires a pair of 
springs to assure movement of a guide mechanism for the separator along 
the desired path. The springs increase the time and cost of assembling the 
separator. The apparatus of the present invention eliminates the need for 
the springs, and thus the cost of the springs and the time and cost of 
assembly of the springs. The present apparatus also requires less force 
from a solenoid than some prior designs, and is highly reliable. 
SUMMARY OF THE INVENTION 
It is an object of the invention to provide apparatus for recirculating 
document sheets as described herein which reduces the likelihood of damage 
to the document sheets. Another object of the invention is to provide 
apparatus of the type described which uses a pin-in-slot type arrangement 
for guiding the separator and wherein the springs used with some previous 
designs have been eliminated. A further object of the invention is to 
provide a sheet separator for a recirculating feeder which requires less 
force from a solenoid to actuate the apparatus and which is highly 
reliable. 
The present invention relates to improvements in apparatus for circulating 
document sheets seriatim along a path leading from the bottom of a stack 
of such sheets to a copying position and then back to the top of the stack 
of sheets. The apparatus has a support for holding the stack of sheets and 
means for feeding the sheets along the path. A separator is engageable 
with the sheet that initially is on top of the stack for separating sheets 
in the stack that have been circulated along the path from sheets in the 
stack that have not been circulated along the path. In response to feeding 
of such top sheet along the path, the separator is returned to the top of 
the stack. More specifically, first and second spaced surfaces are 
provided adjacent the support. A first portion of the separator is located 
between the surfaces, and a second portion of the separator is adapted to 
rest on the top sheet. A force is applied to the first portion of the 
separator by a drive means to move the separator (1) in a first direction 
away from the support after the top sheet has been withdrawn from beneath 
the separator by the feeding means and (2) in a second direction toward 
the support when the top sheet has been returned to the top of the stack 
by the feeding means. A guide slot is defined in the surfaces. A first 
portion of the slot is in the first surface and a second portion of the 
slot is in the second surface. The first slot portion has a ramp extending 
from the bottom of the first slot portion toward the second slot portion. 
The second slot portion has a ramp extending from the bottom of the second 
slot portion toward the first slot portion. A guide pin mounted on the 
first portion of the separator has end portions movable along the slot 
portions. The length of the pin is greater than the spacing between the 
surfaces and less than the distance between either of the surfaces and the 
bottom of the portion of the slot in the other surface. The pin is 
slidable relative to the separator toward and away from the bottoms of the 
slot portions in response to engagement between the end portions of the 
pin and the slot ramps during movement of the separator. The pin and slot 
cooperate during movement of the separator in the first direction to guide 
the second portion of the separator first away from the support and then 
upwardly, and the pin and slot cooperate during movement of the separator 
in a second direction to guide the second portion of the separator toward 
the support.

DETAILED DESCRIPTION OF THE INVENTION 
Referring now to FIG. 1 of the drawings, a recirculating document feeder 
generally designated 10 has a support 12 for receiving and holding a stack 
of document sheets S that are to be copied. Feeder 10 can be mounted on a 
copier/duplicator, for example, having a platen 14 at which document 
sheets are positioned for copying in a conventional manner and as 
described in the before-mentioned U.S. Pat. No. 4,076,408. The sheets are 
circulated seriatim from the bottom of the stack of sheets S on support 12 
along a path that leads to a copying position on top of the platen 14 and 
then back onto the top of the stack of sheets S in the support 12. This 
may be accomplished, for example, by an oscillating vacuum feeder 16 
located beneath the stack of sheets and at one end of the support 12. The 
oscillating vacuum feeder is effective to pull downwardly on the lower 
most sheet in the stack S and feed the end of that sheet into a nip 
between a drive roller 18 and an idler roller 20 recessed into the 
oscillating vacuum feeder. Roller 18 drives the sheet between the 
oscillating vacuum feeder and a sheet guide 22 which directs the sheet 
into a space between the platen 14 and a plate 24 immediately above the 
platen. The sheet is advanced across the platen by drive rollers 26 and 
28. The sheet is stopped on the platen, registered and then illuminated by 
flash lamps (not shown) for making a copy of the document sheet. Then 
rollers 26, 28 drive the sheet off of the platen and between guides 30, 32 
which direct the sheet back to the support and at an elevation so that the 
sheet returns to the support on top of the sheets remaining in the 
support. A sheet can be driven between guides 30, 32 by a roller 34 and a 
cooperating idler roller 36. 
The sheet separator apparatus of the present invention is generally 
designated 40. As described in more detail later, the separator apparatus 
40 includes a separator that is positioned on top of the stack when 
copying operations begin and rides downwardly with the top sheet of the 
stack until that top sheet is removed for copying. Then the member is 
returned again to the top of the stack of sheets after that top sheet is 
returned to the top of the stack. In this manner, the apparatus 40 detects 
completion of copying of the set of sheets once. 
Referring now to FIGS. 2-8, the preferred embodiment of apparatus 40 
comprises a base plate 42 and a pair of guide plates 44, 46. Plate 42 is 
mounted in feeder 10 adjacent the left end of support 12. The guide plates 
are perpendicular to the base plate and are located in substantially 
vertical planes when mounted in the feeder 10. Plates 44, 46 are spaced 
from each other and have generally parallel inner surfaces 48 and 50, 
respectively, facing each other. Plates 44, 46 can be secured to plate 42 
by screws 47, for example. 
A sheet separator 52 has one end portion located between surfaces 48, 50 of 
the plates. The other end portion of the separator is adapted to project 
from the right end of the plates to rest on the sheet on top of the stack 
of sheets S on support 12 as shown in FIGS. 1 and 8. The projecting end of 
separator 52 can pass through slot-like openings 53 and 55 in support 12 
and plate 42, respectively as explained later. 
A solenoid 54 is secured to a mounting plate 56 projecting upwardly from 
plate 42. The solenoid can be held in place by a nut 58. Solenoid 54 has 
an armature 60 located between surfaces 48 and 50 of the plates 44, 46. 
The outer end of the armature is bifurcated, as best shown in FIG. 2, and 
a mounting pin 62 extends through the bifurcated end portion thereof. The 
innermost end of separator 52 is reduced in size and has a slot 64. The 
reduced end portion of the separator is snapped onto the pin 62 to thereby 
pivotally connect the separator to the armature. Thus when the solenoid 54 
is energized the armature 60 is retracted (moved to the left) to thereby 
move the separator 52 to the left as viewed in the drawings. A return 
spring 66 is coiled around the armature 60 and is compressed between the 
nut 58 and the pin 62. Thus when the solenoid 54 is de-energized the 
spring 66 urges the armature 60 and separator 52 to the right. 
A guide slot generally designated 70 is formed in surfaces 48, 50 of plates 
44, 46 respectively. A portion 72 of the slot is formed in surface 48 and 
a second portion 74 of the slot is formed in surface 50. Referring 
specifically to FIG. 3, slot portion 72 comprises a first generally 
horizontal part 76 which extends from the lower right corner of plate 44 
toward the left. At the left edge of part 76 there is an inclined ramp 78 
that extends from the bottom of slot part 76 to surface 48 of plate 44 and 
toward the surface 50 of plate 46. Directly above ramp 78, and spaced 
therefrom, is a first vertical part 80 of the slot portion 72. One end of 
vertical part 80 is generally above ramp 78 and the left end of slot part 
76. A second horizontal part 82 of slot portion 72 extends from the 
vertical part 80 to the right thereof by a distance sufficient to bring 
the right end of part 82 directly above the right end of slot part 76. A 
second vertical part 84 of slot portion 72 extends between the right ends 
of horizontal parts 82 and 76. Thus, slot portion 72 is substantially 
continuous from the bottom of part 80 through parts 82, 84, and 76 to the 
upper end of ramp 78. Slot portion 72 also includes an exit part 86 that 
extends from part 84 to the right edge of the plate 44 to allow for 
insertion and removal of a guide pin described later. 
Portion 74 of the guide slot in surface 50 includes a relatively wide, 
horizontal part 88 located near the bottom part of surface 50 and 
generally facing the ramp 78 and left end portion of part 76 of guide slot 
portion 72. Portion 74 also comprises a vertical part 90 that extends 
upwardly and tapers inwardly from slot part 88 and terminates at its upper 
end in a ramp 92 that extends from the bottom of slot part 90 toward the 
slot portion 72 in surface 48. Ramp 92 is generally aligned with the part 
80 of slot portion 72 whereas part 88 of slot portion 74 is aligned 
generally with the left end of slot part 76 and ramp 78. 
A guide pin 96 is mounted on the portion of separator 52 that is located 
between the plates 44 and 46. The end portions of the pin are movable 
through the slot portions 72 and 74 in the plates for guiding the 
separator 52 through its various positions as described later. Referring 
to FIGS. 2 and 5, the length of pin 96 is greater than the spacing between 
plate surfaces 48, 50 and less than the distance between either of the 
surfaces and the bottom of the portion of the slot in the other surface. 
The pin is slidable relative to the separator in the direction generally 
perpendicular to the length of the separator so that it can move toward 
and away from the bottom of the slot portions 72 and 74 in response to 
engagement between the end portion of the pin and the slot ramps during 
movement of the separator as described later. As the separator is 
initially positioned between plates 44, 46, the pin projects toward plate 
44 and enters the guide slot through part 86 of the slot. 
The pin 96 and slot 70 cooperate during movement of the separator to guide 
the projecting end portion of the separator in a generally rectilinear 
path. Since the solenoid 54 applies a force acting in a generally 
horizontal direction, means are needed for raising the projecting end 
portion of the separator horizontally. In the embodiment illustrated in 
the drawings, this is accomplished by providing a cam 98 (FIGS. 3 and 6-8) 
and a pin 100. The cam is on the lower surface of the separator near the 
innermost end thereof, and pin 100 extends between plates 44, 46 and 
beneath the armature 60 so that it can be contacted by the cam during 
movement of the separator to the left. Thus, as the armature 60 is 
retracted when solenoid 54 is energized, the separator 52 is moved to the 
left from its FIG. 3 position to bring the cam 98 into engagement with the 
pin 100 as shown in FIG. 6. As the armature continues to move to the left, 
cam 98 rides up on pin 100 and swings the separator about pin 62 to 
thereby lift the outermost end of the separator in a vertical direction to 
the position shown in FIG. 7. When in the FIG. 7 position, the right end 
of the separator is above the level of the top sheet on support 12. 
Preferably, means are provided for sensing when the separator 52 reaches 
its lowermost position, as occurs when the sheet it is resting on is fed 
from the support 12 for copying. In the embodiment illustrated in the 
drawings, this can be accomplished by providing a switch 102 (FIG. 3) 
which is contacted by the outer end of the separator when it reaches its 
lowermost position to thereby close the switch. Alternatively, the 
position of the separator can be sensed optically or by some other means 
in order to close a switch such as shown in 102. Closing of the switch 102 
is detected by a logic and control unit (LCU) of the copier/duplicator 
which controls operation of the solenoid 54. 
Operation of the apparatus of the invention will now be described. When the 
apparatus is in an inactive condition with no sheets in the support 12 of 
the recirculating feeder 10, the separator 52 occupies the position 
illustrated in FIG. 3. The projecting end portion of the separator holds 
switch 102 closed to provide a signal to the LCU indicating that the 
separator is at its lowermost position. However, since no sheets are in 
the feeder for copying, the LCU does not energize the solenoid 54 and the 
separator remains in this position. At this time, the pin 96 is located 
relative to the guide slot in surfaces 48 and 50 so that the pin is in the 
portion of the slot formed in surface 48 and generally at the intersection 
of slot parts 76 and 84. 
When a machine operator places sheets S to be copied onto the support 12 of 
the recirculating feeder and initiates operation of the apparatus, the LCU 
immediately energizes the solenoid 54 to retract the armature 60 and thus 
move the separator 52 through its FIG. 6 position to its FIG. 7 position. 
As this occurs, pin 96 moves along guide slot part 76 generally to the 
position illustrated in FIG. 6. At this time, cam 98 on the bottom of the 
separator engages the pin 100 extending between the plates 44, 46 to 
thereby pivot the separator in a counterclockwise direction upwardly about 
the axis of pin 62, thereby to move the separator to its FIG. 7 position. 
As this occurs, one end of the pin 96 first engages the ramp 78 of slot 
portion formed in surface 48. As the pin is moved upwardly with the 
separator, the pin is forced laterally through the separator by the ramp 
78 so that the other end of the pin enters the part 88 and then part 90 of 
the slot portion 74 in surface 50. As the pin 96 approaches its fully 
elevated position, the projecting end of the pin strikes the ramp 92 in 
surface 50, and the ramp is effective to drive the pin laterally with 
respect to the separator to move the other end of the pin into the part 80 
of the slot portion 72 formed in surface 48. 
At this time the LCU de-energizes solenoid 54. The armature 60 is extended 
and the separator 52 is moved to the right by the force of spring 66. 
However, the separator does not move downwardly through slot part 90 
because the pin has been thrust laterally sideways to locate the end of 
the pin in slot part 80 and the bottom of that slot part limits downward 
movement of the separator. As armature 60 is extended by the spring, the 
pin 96 travels from slot part 80 through slot part 82 into the upper end 
portion of slot part 84. This is the position illustrated in FIG. 8 of the 
drawings. At this time the pin can drop downwardly through slot part 84 
until the projecting end portion of the separator engages and rests on the 
top sheet of the stack of sheets in the support 12. The only force urging 
the separator against the sheets is the force of gravity. Since separator 
52 is a very light-weight member, the separator will not damage the 
document sheets. 
As is known in the art, during operation of the recirculating feeder, 
sheets S are removed from the bottom of the stack, fed to the platen 14 
for exposure and copying and then returned to the top of the stack on the 
support 12. As sheets are returned to the stack, they rest on top of the 
separator 52. Thus, the separator gradually works downwardly with the 
sheet that was initially on top of the stack of sheets S. When that sheet 
reaches the bottom of the stack and then is fed from the support 12, the 
projecting end of the separator can drop through the openings 53, 55 in 
the bottom of the support 12 and plate 42 to the position illustrated in 
FIG. 3 where it closes switch 102 to thereby signal the LCU that the 
entire set of sheets has been circulated once for copying. 
After a brief time delay, which allows the top sheet of the stack to be 
returned from the platen to the top of the sheets in the support 12, the 
solenoid 54 is again energized to retract the separator 52 and move it 
through the positions shown in FIGS. 5 and 6. Then the solenoid is 
de-energized so spring 66 can return the separator through its FIG. 8 
position and onto the top sheet in the stack. This process is repeated 
until the set of sheets on support 12 has been copied the desired number 
of times. When the set of sheets has been copied for the last time, the 
separator closes switch 102 to send a signal to the LCU which recognizes 
that the copying cycle is complete and does not energize the solenoid 
again. 
A number of advantages are achieved by the present invention. First of all, 
there is only a slight force applied by the separator to the document 
sheets. Therefore, there is no damage to document sheets, as sometimes 
occurred with prior rotary separators. In addition, the invention 
eliminates the need for springs commonly used with pin-in-slot type guide 
arrangements for moving a separator in a generally rectilinear path. This 
reduces the expense of the apparatus and simplifies assembly of the 
apparatus. At the same time, the provision of the guide slot of the 
invention in the two facing surfaces 48, 50, together with the sliding pin 
96 which can travel along the slot portions in either of the surfaces 
provides the desired positive and controlled movement of the separator in 
a generally rectilinear manner even through the forces applied by the 
solenoid 54 and spring 60 are generally horizontal. Moreover, the 
apparatus is very reliable and requires less force from the solenoid than 
some prior apparatus. 
The invention has been described in detail with reference to a preferred 
embodiment thereof, but it will be understood that variations and 
modifications can be effected within the spirit and scope of the 
invention.