Note: Descriptions are shown in the official language in which they were submitted.
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FIELD OF THE INVENTION
This invention relates to sheet lifters for loose
leaf ring binders and to a method for installing shee-t
lifters in loose leaf ring binders.
BACK~ROUND OF THE INVENTION
Loose leaf ring binders often use spring-loaded two
piece ring elements to retain sheets of paper in the binder.
These ring elements are typically circular or approximately
circular and are joined to the loose leaf ring binders along
a metal strip attached to the spine of the binder. Sheets
of paper may become trapped between the cover of the loose
leaf binder and the ring element near the point of
connection of the ring element to the binder spine, and then
are particularly easily torn at the holes in the sheet of
paper throuqh which the ring elements pass. To deal wi-th
this problem, sheet lif-ters are commonly used to prevent the
sheet from entering the space between the ring e]ement and
the binder near the spine of the binder.
When sheet lifters are used, they are usually
20 installed in the binders by the binder manufacturer.
Typically this hàs been done by manually opening the ring
elements of each loose leaf binder, inserting the ring
elements in holes in the sheet lifters and closing the ring
elements. The need to open and close the binder ring is
25 time consuming and therefore costly. It is also ~uite
damaging to the hands of those doing the installation, since
binder rings usually need considerable pres~sure to open and
close them.
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SUMMARY O~ THE INVENTION
This invention provides a sheet lifter which may be
installed on a loose leaf ring binder without opening the
ring elements of the binder, and which at the same time
5 resists being detached from the ring elements once attached.
In a broad embodiment of such a sheet lifter for a
loose leaf ring binder, said binder having at least two
ring elements, the sheet lifter comprises: a plate having
opposite sides and a front edge extending be-tween said
10 sides, at least two openings formed in said plate adjacent
said edge of said plate for receiving said ring elements,
each of said openings having a slit extending between the
opening and said edge, said plate being formed of resilient
yielding material at least in regions adjacent said slits,
15 said slits being narrower than the cross sectional width of
said ring elements, whereby the force required to attach
said plate to said ring elements, when said ring elements
are closed, by movement of said plate towards said ring
elements in a direction perpendicular to the plane of said
20 plate is less than the force required to detatch said plate
from said ring elements, when said ring elements are closed,
in a directlon parallel to the plane:of said plate.
This invention also provides, in another aspect, a
method for installing a sheet:lifter on a loose leaf bi~nder,
25 the method comprising: positioning a sheet lifter of the
type described with said sllts ad~acent said ring elements
and spaced therefrom ln a direction perpendicular to the
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plane of said sheet lif-ter, and exerting force on said shee-t
lifter in said direc-tion to engage said openings with said
ring elements.
BRIEF DESCRIPTION OF THE DRAWINGS
Preferred embodiments of the invention will now be
described by way of example without intending to restrict
the scope of the invention as defined in the claims to the
specific embodiments described and with reference to the
drawings in which:
Figure 1 is a side view of part of a conventional
loose leaf ring binder with two sheet lifters, one
sheet lifter not attached;
Figure 2 is a top view of a prior art sheet lifter;
Figure 3 is a top view of the sheet lifter having
slits in one configuration according to the
invention;
Figure 4 is a top view of a sheet lifter having
differentially offset slits;
Figure 5 is a front view of a machine for
installing a sheet lif-ter having slits on a loose
leaf binder, showing a sheet lifter in position for
installation on a loose leaf ring binder;
Figure 6 is a -top view of a sheet lifter slide
feeder for the machine shown in Figure 4; and
Flgure 7 is a cross section of a slide feeder along
along lines 7-7 of Figure 6.
DESC~IPTION OF THE PREFERRED EMBODIMENTS
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Loose leaf ring bi~nders commonly have two, three or
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four ring elements, the ring elements being a fixed distance
apart as determined by industry standards. The ring
elements are typically circular (as shown in Figure 1) or
slant-D shaped as shown in Figure 5. Referring to Figure 1,
sheets of paper in a loose leaf ring binder may become
trapped in the gap shown at 10 between the ring element 12
and the loose leaf ring binder cover 14 when the cover is
closed. The pressure of the cover against the sheet of
paper tends to pull the trapped sheet out of the gap 10
which because of adjacent sheets of paper may put pressure
on the paper near the holes through which the ring elements
pass and thus tear the paper.
To prevent the sheets of paper entering the gap 10,
a sheet lifter 16 is frequently installed which occupies the
gap 10 and holds the sheets of paper away from the gap.
Such a sheet lifter 16 takes the form of a plate having
sufficient thickness to act as a barrier to paper entering
the gap 10, and sufficient width (for example 3 inches to 5
inches) to cooperate with the loose leaf ring binder cover
14, ring element 12 and ring element holder 18 to move with
the cover as it closes, as is known in the art. The sheet
lifter 16 may be slightly curved (for example with a rise at
the center of approximately one quarter of an inch) or
straight as shown, and may be made of any of various
25 plastics or cardboard flber or other sufficiently rigid
material.
Figure 2 shows a typical prior art sheet lifter
with three elongate openings 20 for receiving the ring
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elements (not shown) of a loose leaf ring binder. These
openings 20 must be wide enough to fit the ring element
loosely so that the sheet lifter 16 is free to move on the
ring element. It is desirable that the opening 20 be
elongated to allow for the curvature of the ring element as
it passes through the sheet lifter. These prior art sheet
lifters 16 are installed during manufac-ture by manually
opening the ring elements, placing the sheet lifter 16 on
the ring elements and closing the ring elements.
Figure 3 shows one embodiment of a sheet lifter
16-1 according to the invention. Openings 20 are provided
with slits 22 extending between the openings 20 and the
adjacent or front edge 24 of the sheet lifter. The slits 22
are shown extending perpendicular to the edge 24 but they
may be slanted, curved or kinked. Although the slits 22 are
shown as perforating the sheet lifter 16-1 completely they
may be closed, for example by a film of plastic during
manufacture, so long as the film is sufficiently fragile to
be perforated upon attachment (as described below) to the
ring element.
The slits 22 are shown as connecting to each
opening 20 at a point 26 offset from the midpoint 28 of the
end of the opening 20 (the midpoint is also the point
closest to the edge 24). As shown here, the end of the
opening 20 closer to the edge 24 is circular and concave in
25 relation to the edge of the sheet lifter 16-1, as is typical
of most sheet lifters, and the slits 22 are extensions of
the elongate sides 30 of the openings 20. If the slit
extends perpendicularly from the edge 24, as shown, then the
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slits 22 will be tangential to the elongate sides 30 of the
openings 20. If, for example, the slits 22 connected at the
mid points 28, the sheet lifter 16-1 would be more readily
detached from the ring element as described below.
Each slit 22 and opening 20, and the adjacent edge
24 of the sheet lifter 16-1 define at least one flap 32
~hich is capable of yielding under pressure exerted in a
direction perpendicular to the plane of the plate to allow a
ring element to pass into the opening 20. If the slits 22
are connected at the central point 28 of the end of the
opening 20 adjacent to the edge 24 then each slit 22 and
opening 20 and the adjacent edge 24 define two flaps (not
shown). Slits 22 are formed narrower than the cross
sectional width of the ring element measured in a plane
perpendicular to the drawing in Figure 1 so that the ring
element cannot easily pass through the slits.
The sheet lifter 16-1 is preferably constructed
from resilient yielding material. Numerous plastics are
suitable, such as polypropylene or high density
polyethylene. Paper alone is too flexible, although
eardboard could be used especially if laminated with plastic
film, and if sufficiently resilient and yielding. If made
of plastic, the sheet lifter 16-1 may be manufactured by
injection moulding, or dye cut after manufacture by
extrusion or as calendar sheet stock.
It is desirable that the sheet lifter 16-1 have
sufficient thickness to function as a sheet lifter and have
the desired resilience. It lS desirable~ to have a sheet
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lifter at least about 0.020 inches thick in regions adjacent
the slits, and preferab]y about 0.050 inches to 0.060 inches
thick. It is only in the region adjacent the slits for
which the thickness is of concern because this is where the
sheet lifter lifts the sheets away from the gap between ring
element and binder. However, the sheet lifter may not be of
uniform thickness, since it is only desirable that the
effective thickness (the amount by which a sheet is lifted
by the sheet lifter, which is what is meant by "thickness"
in the claims) be greater than about 0.020 inches.
The sheet lifters are installed as follows.
Firstly, a sheet lifter 16-1 is positioned as shown for
sheet lifter 16 of Figure 1, with its slo-ts ~not shown)
adjacent and just above (or even touching) the ring elements
15 12 of a loose leaf binder. The sheet lifter 16-1 is then
forced downwardly onto the ring element 12 by pressure in
the direction of arrow A (that is, perpendlcular to the
plane of the sheet lifter 16-1). Under pressure from the
ring elements, the material of the sheet lifter 16-1 in
20 regions adjacent the slits 22 (including the flaps 30)
yields and lifts upwardly to allow pass~age of the ring
elements 12 into the openings 20. Once the ring elements 12
are in the openings 20, the resilience of -the sheet lifter
16-1 in the regions adjacent to the slits 22 (including the
25 flaps 30), returns the material of the sheet lifter into its
unstressed position. This prevents the sheet lifter 16-1
from being detached from the ring elements 12 in a direction
parallel to the plane of the sheet llfter except by
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considerable force greater than the force required for
attachment.
Preferably the slits 22 are oriented perpendicular
to the edge 24 of the sheet, as shown. The slits 22 can
5 however be slanted with respect to the edge 24 of the sheet
lifter 16-1, but the slant should not be too great since
otherwise the sheet lifter could not be installed without
carefully working the ring element into the slit 22.
Installation would be still harder if different slits were
10 slanted in different directions. Thus it is desirable that
the slits 22 extend between the edge 24 and the opening 20
within a sector defined by straight lines (not shown)
extending between the edge 24 and opening 20 at angles no
greater than about 45 degrees to the edge 24. In addition,
15 the material of which the sheet lifter 16-1 is made cannot
be so resistant to yielding that it might break during
installation although for machine installation it would not
be necessary that the sheet lifter be installed with hand
pressure. The claims are to be read with these limitations
20 understood, since they would be clear to a person skilled in
the art~
Once attached, the sheet lifter 16-1 described here
is extremely difficult to remove by force exexted in the
direction of arrow B of Figure 3, i.e. in a direction
25 parallel to the plane of the sheet lifter 16-1 and
perpendicular to edge 24. Referring to Figure 3, if the
slits 22 are connected at points 26 -to the openings, the
resisting force~ to detachment is provided by the force
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required to deflect the material adjacent the slits 22
(including the flaps 30) sufficiently -to widen the slits 22
to allow passage of -the ring element. It is for this reason
that the material of the sheet lifter 16-1 in regions
5 adjacent the slits 22 be resilient, not merely yielding.
Since the slits 22 are tangent to the sides 30 of openings
20, each ring element 12 (of which one is shown in dotted
lines in Figure 3) is caught in -the concavity at the end of
the opening 20. Thus, a pulling force in the direction of
10 arrow B tends to pull the ring element 12 further into the
concave end of opening 20 rather than to open the slit 22.
The result is that -the material of the lifter 16-1 virtually
must be destroyed (which requires a grea-t deal of force) to
pull lifter 16-1 out of the rings in the direction of arrow
15 B. This is so even though the sheet lifter 16-1 can be
"snapped" into position in the direction of arrow ~ of
Figure 1 with (typically) relatively little force.
If the slits 22 are connected to the openings 20 at
points 26 closer to or at the mid points 28 of the openings
20 20, closest to the edge of the sheet lifter, -then much less
force is required to remove the sheet lifter 16-1 from the
rings in the direction of arrow B than if the slits 22 are
connected at the points 26. Such an arrangement would
therefore be less desirable.
In addition, the narrower the slits 22 are, the
greater the force which is required to remove the sheet
lifter 16-1, with greatest force required when the slits 22
have essentially no thickness, being~ only a break in -the
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sheet lifter 16-1. However, if the sheet lifter 16-1 is
manufactured by injection moulding, the width of the slit is
limited by the required thickness of the part of the mould
which creates the slit to prevent damage to the mould during
5 manufacture.
Reference is next made to Figure 4, which shows
another embodiment of a sheet lifter according to the
invention. In Figure 4 the sheet lifter is indicated at
16-2 but corresponding reference numerals indicate parts
corresponding to those of Figure 2. Lifter 16-2 is provided
with slits 22 at least two of which, here slits 22A and 22C
or 22B and 22C are offset in the openings 20 in different
directions. Thus, slits 22A, 22B are tangent to the top
side of openings 20A, 20B as drawn, while slit 22C is
15 tangent to the bottom side of opening 20C. Therefore, the
distance between the points 268, 26C where the slits 22B,
22C connect to the openings 20B, 20C will be different from
the distance between the centres of ring elements 12B, 12C
shown in dotted lines in the openings 20B, 20C. This
20 arrangement ensures that no matter where the ring elements
are located in the openings 20, one ring element will not be
adjacent to a slit, and will be harder to remove than
otherwise. This arrangement is possible because ring
elements are spaced apart in loose leaf ring binders by
25 uniform distances defined by industry standards. The Figure
4 embodime~nt is superior to the Figure 3 version because the
Figure 4 ~version is vlrtually impossible to remove in the
direction of arrow B without destroying the sheet lifter
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16-2 in the process. Nevertheless liEter 16-2 can be
snapped into the binder rings from above with no more
pressure than the lifter 16-1, exactly as described for
lifter 16-1.
The sheet lifter according to the invention may be
attached as described by hand, or using a machine designed
for that purpose. An example of such a machine will now be
described referring to Figures 5, 6A and 6B.
Loose leaf ring binders are delivered to an
10 operator, for example by conveyor (not shown), and placed by
the operator into assembly position in gauging nest 34
underneath an air operated press 36. The loose leaf ring
binders are preferably delivered open, oriented and at
reasonably fixed intervals for ease of handling. The loose
15 leaf ring binder 38 shown here has ring elements 40 of the
slant-D type.
Left and right sheet lifters 46 are stacked in
hoppers 42 and 44, at left and right sides of the press 36.
The sheet lifters 46 are fed into assembly position by air
20 operated slides 48 and 50. Slide 48 is shown here in
position to collect the next sheet lifter 46 from the hopper
42 while slide 50 is shown in position over the loose leaf
ring binder 38. A centering guide 51 ensures that the
slides 48, 50 stop in the correct positions over the binders
25 38.
Slide 48 is shown in Flgures 6A and 6B with a ledge
52 extendlng along its rear and side edges (but no-t its
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front edge) for supporting the sheet lifters 46. Slide 50
has the same arrangemen-t. AS the slides 48 and 50 push the
sheet lifters 46 into position, the press 36 with a downward
stroke using press pads 54, made for example of rubber,
5 pushes the sheet lifters, in position as shown by sheet
lifter 56 on slide 50, off the slides and onto the ring
elements 40 of the loose leaf ring binder 38. The sheet
lifter slits engage automatically as the resilient yielding
plastic snaps around the ring elements 40. The sheet
10 lifters bend sufficiently during this process so that their
peripheries move inwardly, clear of ledge 52 (which is very
narrow), so that the shee-t lifters can be pushed downwardly
off the slides. As the press 36 returns to its top
position, slide 48 and 50 return to the starting position
15 (shown by slide 48) to pick up the next sheet lifter 46.
The operator then removes the loose leaf ring binder 38 from
the gauging nest 34, closes the loose leaf ring binder and
places it back on the conveyer (not shown) for packaging.
Although the sheet lifters have been shown as flat
~0 i.e. planar, they may also be curved (to provide more lift)
as mentioned and as known in~the industry. This has no
effect on the invention, and in this description and in the
claims the term "planeii of the Iifter is used to indicate
the general plane which the sheet lifter is in and does not
25 restrict the lifter to being flat.
Various modifications of -the embodiment described
here may be made without dep~arting from the spirit of the
invention as~defined in the claims.~
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