Apparatus for aligning sheets in a stack

An apparatus for aligning and squaring a stack of sheets has a support plate having a generally horizontal and flat support surface adapted to support the stack of sheets, a guide projecting upward from the support surface and having an abutment face directed in a predetermined direction generally parallel thereto, and a generally horizontal rod vertically spaced from the surface and stack and extending in the direction. A pusher element carried on the rod is slidable thereon in the direction, friction alone linking the element and rod together in the direction. This pusher element is engageable with a sheet on the surface. A stop facing opposite to the direction is also engageable with the element. A drive reciprocates the rod in the direction through a predetermined stroke toward and away from the guide. Thus on displacement toward the guide the element engages and pushes a sheet opposite the direction until the sheet engages thereagainst, at which time the element slides on the rod. On opposite displacement the element engages the stop and is displaced relative to the rod in the direction to its starting position on the rod.

FIELD OF THE INVENTION 
The present invention relates to an apparatus for aligning sheets in a 
stack. More particularly this invention concerns an apparatus used in a 
copier or a copy sorter and stapler for squaring up the stacks of copies. 
BACKGROUND OF THE INVENTION 
It is necessary in many copying and sorting machines, such as described in 
commonly owned allowed patent application Ser. No. 533,578 filed Sept. 19, 
1983 now U.S. Pat. No. 4,497,478, of R. Reschenhofer et al, to provide a 
mechanism for squaring up, that is aligning one atop the other, the sheets 
that are fed in either one at a time or in groups. When the sheets are to 
be stapled or bound by an automatic device, it is absolutely essential 
that they be in proper alignment. 
A standard such device is German Pat. No. 649,028. It has a support plate 
on whose surface the sheets are deposited. Several pins are fixed along 
one edge of the plate, and several movable pins carried on arms or rods 
underneath the plate project up through slots in this plate. A mechanism 
is provided to move these latter pins toward the stationary ones to push 
the sheets thereagainst and thereby align and square them up. 
The main problem with such a device is that the stroke of the movable pins 
must be very carefully adjusted. If it is too short the sheets will not be 
properly aligned; if it is too long the edges of the sheets will be 
crumpled. In addition if a sheet gets slightly jammed, it will be damaged, 
necessitating manual correction. 
OBJECTS OF THE INVENTION 
It is therefore an object of the present invention to provide an improved 
apparatus for aligning sheets. 
Another object is the provision of such an apparatus for aligning sheets 
which overcomes the above-given disadvantages, that is which does not need 
to be readjusted whenever sheet size changes, and that will normally not 
damage even a malpositioned sheet. 
SUMMARY OF THE INVENTION 
An apparatus for aligning and squaring a stack of sheets according to the 
invention has a support plate having a generally horizontal and flat 
support surface adapted to support the stack of sheets, a guide projecting 
upward from the support surface and having an abutment face directed in a 
predetermined direction generally parallel thereto, and a generally 
horizontal rod vertically spaced from the surface and stack and extending 
in the direction. A pusher element carried on the rod is slidable thereon 
in the direction, friction alone linking the element and rod together in 
the direction. This pusher element is engageable with a sheet on the 
surface. A stop facing opposite to the direction is also engageable with 
the element. A drive reciprocates the rod in the direction through a 
predetermined stroke toward and away from the guide. Thus on displacement 
toward the guide the element engages and pushes a sheet opposite the 
direction until the sheet engages thereagainst, at which time the element 
slides on the rod. On opposite displacement the element engages the stop 
and is displaced relative to the rod in the direction. 
According to another feature of this invention the drive means reciprocates 
the element through a stroke at least equal to the difference in size 
between the largest sheet and smallest sheet to be aligned by the 
apparatus. Thus the apparatus need not be readjusted when sheet size 
changes, and when a sheet is misaligned, the apparatus of this invention 
can continue to function without crumpling its edge, normally aligning it 
during a later operating cycle. Since the force exerted on the sheet is 
purely determined by the speed and inertia of the pusher element and by 
the friction between this element and the rod, it is possible to use just 
enough force to do the aligning job, without running any risk of damaging 
a sheet. 
The element of this invention can be a disk centered on and rotatable about 
the rod, and a hub fitted on the rod and of a length measured in the 
direction greater than the diameter of the rod. Thus sufficient friction 
can be created to align even a heavy sheet, and the long hub can prevent 
the disk from canting on the rod. 
Although only a single such element need be provided, which is normally 
only done when the plate is inclined considerably for automatic alignment 
against a second such guide provided on the plate facing generally 
perpendicular to the first mentioned guide. It is also possible to provide 
a second such rod extends in a second direction generally perpendicular to 
the first-mentioned direction and a second such element is provided on the 
second rod. The drive means is connected to both of the rods to displace 
same in the respective directions. This drive means includes a drive shaft 
rotating about an axis generally perpendicular to both of the directions, 
respective first and second generally perpendicular cranks carried on and 
extending radially from the shaft, and respective first and second rigid 
links connected between the cranks and the rods for transmitting force 
therebetween. The first and second cranks are of different lengths that 
correspond generally to the variations in the respective dimensions of the 
sheets. With this type of drive perfectly synchronous operation of the two 
pushers is ensured, so that once a sheet's static friction is overcome it 
can easily be moved into position. It is also possible to gang several 
such elements along one edge of the sheets, a feature used when sheets of 
very large format are being worked with. 
The element according to this invention can also be a tab extending upward 
from the rod through the plate and having a center of gravity below the 
rod. This tab is not centered on the rod, but is rotatable thereon to 
compensate for transverse shifting of the sheet it is pushing, and is 
provided below the rod with a weight to return it to an upright position 
if it is tipped.

SPECIFIC DESCRIPTION 
As seen in FIGS. 1, 2, and 3, the apparatus for aligning or squaring up a 
stack 5 of sheets according to this invention has a housing 1 provided 
with a base plate 2 on which a sheet-support plate 4 is supported by posts 
3. This plate 4 has an at least generally horizontal and planar upper 
surface and is provided with two edge guides or abutments 6, 7 extending 
along adjacent edges thereof at 90.degree. to each other. The plate 4 may 
be inclined somewhat toward the edge guides 6 and/or 7 so that gravity can 
assist aligning the sheet stack 5 therewith. 
Underneath the plate and parallel to the guides 6 and 7 are two rods 8 and 
9 supported in respective identical outer and inner pillow blocks 11 and 
12 so that these rods 8 and 9 can slide along the respective axes 8A and 
9A relative thereto. These rods 8 and 9 carry respective identical 
circular disks 10 centered on and perpendicular to the respective axes 8A 
and 9A and extending through respective holes 4a and 4b in the plate 4 and 
other such holes 2a in the plate 2. These disks 10 are each fixed to a 
respective hub 13 having a central bore that is slightly larger than the 
outer diameter of the respective rod 8 or 9, and are not fixed to the rods 
8 and 9. Thus, when as described below the rods 8 and 9 are reciprocated 
axially, the disks 10 will be entrained axially purely and exclusively by 
frictional engagement of the hubs 13 on the rods 8 and 9. 
The hubs 13 have an axial length substantially greater than the diameters 
of their bores to prevent canting of the disks 10 on the rods 8 and 9 and 
to maximize frictional contact between the hubs 13 and the rods 8 and 9. 
In addition each of the outer pillow blocks 11 is provided with a 
roller-type bumper 21 that is engageable with the outer face of the 
respective disk 10. 
A drive for reciprocating the disks 10 has a motor 19 whose output shaft 18 
is centered on an axis 18A perpendicular to the plane of the axes 8A and 
9A and lying at the intersection thereof. This shaft 18A carries a 
radially extending crank 14 and 15. The outer end of the crank 14 carries 
a pivot 16 on which is mounted the inner end of a rigid link 20 whose 
outer end is pivoted on the end of the rod 8. The other crank 15 similarly 
has at its outer end a pivot 17 on which is pivoted another such link 20 
connected to the inner end of the shaft 9. 
The relative lengths of the cranks 14 and 15 between the axis 18A and the 
respective outer pivots 16 and 17 are different, with the crank 15 longer 
than the crank 14. These two lengths normally form a ratio equal to the 
standard width-to-length ratio for a standard page, typically equal to 
8.5:11, which ratio is generally equal to the normal variation in size in 
the respective directions on the sheet. 
Thus as seen in FIG. 2 the pivot 17 and the rod 9 are moved through an 
axial stroke a.sub.1 and the pivot 16 and rod 8 through a shorter stroke 
a.sub.2. These strokes a.sub.1 and a.sub.2 exceed by respective extents 
c.sub.1 and c.sub.2 the differences b.sub.1 and b.sub.2 in sheet size 
normally encountered. 
In use copies are dropped onto the top surface of the plate 4 generally 
against the guides 6 and 7. The motor 19 rotates the cranks 14 and 15 to 
reciprocate the shafts 8 and 9, axially frictionally entraining the disks 
10. When the inner face of each disk 10 strikes the respective edge of the 
copy, its inertia plus the force transmitted frictionally between the 
shaft 8 or 9 and the respective hub will be enough to push the opposite 
edge of copy against the respective guide 6 or 7. Rotation of the disks 10 
about the axes 8A and 9A permits simultaneous displacement in two 
orthogonal directions. 
Once the opposite edge of each copy engages the respective guide 6 or 7, 
the copy will stop and the respective disk 10 will slide on the rod 8 or 
9, moving axially outward, that is away from the axis 18A, thereon. 
Thereafter, when the rod reverses, the disks 10 will engage outward 
against the bumpers or stops 21 and will be pushed back to their normal 
starting positions, so that the operation can take place again on the next 
sheet copy. Since these disks 10 are driven by a crank, their speeds will 
increase and decrease sinusoidally, thereby minimizing inertial slippage 
on the rods 8 and 9 when they change direction. 
Such an arrangement will therefore simply and accurately square up and 
align the copies of the stack. This action will be effective whether the 
stack 5 is formed of individual sheet copies, or of stapled together 
pamphlets or bundles.