CA1264637A - Sheet lifter for loose leaf ring binders and method of installing sheet lifters in loose leaf ring binders - Google Patents

Abstract

TITLE: SHEET LIFTER FOR LOOSE LEAF RING BINDERS
AND METHOD OF INSTALLING SHEET LIFTERS
IN LOOSE LEAF RING BINDERS.

ABSTRACT OF THE DISCLOSURE

A sheet lifter for a ring binder has slits connecting the edge of the sheet lifter to the holes for the rings. The slits are preferably tangential to the sides of the holes, and one slit is preferably offset toward the opposite side of the lifter from the other slit or slits.
The lifter is made of resilient yielding material so that it may be simply pressed onto the rings without opening the rings but cannot easily be removed without opening the rings. A method is also described for installing the sheet lifter in similar manner.

Description

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
_ Loose leaf ring bi~nders commonly have two, three or .; . ~

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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~2~37 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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L7~ i~ 3 7 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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Claims (29)

THE EMBODIMENTS OF THE INVENTION IN WHICH AN EXCLUSIVE
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS.

1. A sheet lifter for a loose leaf binder, said loose leaf binder having at least two ring elements, said sheet lifter comprising:
a plate having opposite sides and a front edge extending between said 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;
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 plate is less than the force required to detach said plate from said ring elements, when said ring elements are closed, in a direction parallel to the plane of said plate.

2. The sheet lifter of claim 1 in which said slits are connected to said openings at points laterally offset from the part of said openings closest to said front edge.

3. The sheet lifter of claim 2 in which each said opening is elongate and has two elongate sides and a front end which is concave with respect to said front edge, and each said slit is connected to a said front end adjacent one of said elongate sides.

4. The sheet lifter of claim 1 in which the distance between at least two of said slits measured between their points of connection to their respective openings is different from the distance between the centres of ring elements received by said respective openings.

5. The sheet lifter of claim 3 in which the distance between at least two of said slits measured between their points of connection to their respective openings is different from the distance between the centres of ring elements received by said respective openings.

6. The sheet lifter of claim 1 in which said slits extend perpendicularly from said edge.

7. The sheet lifter of claim 2 in which said slits extend perpendicularly from said edge.

8. The sheet lifter of claim 3 in which said slits extend perpendicularly from said edge and are tangential to said elongate sides of said openings.

9. The sheet lifter of claim 4 in which said slits extend perpendicularly from said edge.

10. The sheet lifter of claim 5 in which said slits extend perpendicularly from said edge and are tangential to said elongate sides of said openings.

11. The sheet lifter of claim 1 in which sheet lifter has a thickness of at least about 0.020 inches adjacent said slits.

12. The sheet lifter of claim 2 in which sheet lifter has a thickness of at least about 0.020 inches adjacent said slits.

13. The sheet lifter of claim 3 in which sheet lifter has a thickness of at least about 0.020 inches adjacent said slits.

14. The sheet lifter of claim 4 in which sheet lifter has a thickness of at least about 0.020 inches adjacent said slits.

15. The sheet lifter of claim 5 in which sheet lifter has a thickness of at least about 0.020 inches adjacent said slits.

16. The sheet lifter of claim 6 in which sheet lifter has a thickness of at least about 0.020 inches adjacent said slits.

17. The sheet lifter of claim 7 in which sheet lifter has a thickness of at least about 0.020 inches adjacent said slits.

18. The sheet lifter of claim 8 in which sheet lifter has a thickness of at least about 0.020 inches adjacent said slits.

19. The sheet lifter of claim 9 in which sheet lifter has a thickness at least about 0.020 inches adjacent said slits.

20. The sheet lifter of claim 10 in which sheet lifter has a thickness at least about 0.020 inches adjacent said slits.

21. The sheet lifter of claim 1 in which said plate is formed from polypropylene or high density polyethylene.

22. The sheet lifter of claim 2 in which said plate is formed from polypropylene or high density polyethylene.

23. The sheet lifter of claim 3 in which said plate is formed from polypropylene or high density polyethylene.

24. The sheet lifter of claim 4 in which said plate is formed from polypropylene or high density polyethylene.

25. The sheet lifter of claim 5 in which said plate is formed from polypropylene or high density polyethylene.

26. A sheet lifter for a loose leaf binder, said loose leaf binder having at least two ring elements, said sheet lifter comprising:
a plate formed of resilient yielding material having an effective thickness for sheet lifting of about 0.020 to 0.060 inches, said plate having opposite sides and a front edge extending between said sides;
at least two elongate openings each having two elongate sides and being formed in said plate adjacent said edge of said plate for receiving said ring elements;
the end of each of said openings closest to said edge being concave in relation to said edge and being closest to said edge at a central point of said end; a slit connected to each of said openings at a point offset from said central points, said slit extending substantially perpendicularly from said edge and being tangential to one of said elongate sides and said slits being narrower than the cross sectional width of said ring element; and the distance between at least two of said slits measured from their points of connection to their respective openings being unequal to the distance between the ring elements received by said openings;
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 plate is less than the force required to detach said plate from said ring elements, when said ring elements are closed, in a direction parallel to the plane of said plate.

27. The sheet lifter of claim 26 in which said plate is composed of polypropylene or high density polyethylene.

28. A method of installing a sheet lifter in a loose leaf binder having at least two ring elements, said sheet lifter being formed of resilient yielding material and having formed in said sheet lifter openings for receiving said ring elements and slits connecting said openings to the adjacent edge of said sheet lifter, the method comprising:
positioning said sheet lifter with said slits adjacent said ring elements and spaced therefrom in a direction perpendicular to the plane of said sheet lifter; and exerting force on said sheet lifter in said direction to engage said openings with said ring elements.

29. The method of claim 28 and including the step of ensuring that the distance between at least two of said slits measured from their respective point of connection to their respective openings is different from the distance between the centres of their respective ring elements.