WO2005000081A1

WO2005000081A1 - Sheet dispenser

Info

Publication number: WO2005000081A1
Application number: PCT/US2004/017653
Authority: WO
Inventors: Craig D. Thompson; Timothy J. O'leary
Original assignee: 3M Innovative Properties Company
Priority date: 2003-06-23
Filing date: 2004-06-04
Publication date: 2005-01-06
Also published as: US20040256405A1; AR049649A1; EP1638438A1

Abstract

A dispenser package (10) for durable index tabs includes a housing (12) attached to a base (14), in which the housing (12) consists of interconnected side walls (16, 18) and end walls (20, 22) and a cover (26). The housing (12) and base (14) define a chamber for holding a stack of durable index tabs. The cover (26) comprises a pair of flanges (28, 30), each of which has one end (32) that is attached to one of the end walls (29, 22). The flanges (28, 30) have a pair of opposing edges (36) that are spaced from the side walls (16, 18) of the housing (12). The ends of the flanges (28, 30) opposite to the ends (32) that are attached to the end walls (20, 22) of the housing (12) define a relatively wide opening of the cover (26) for dispensing index tabs made of a relatively inflexible material. Each flange incorporates an elliptical relief (48) adjacent to the opening by forming an arched step in the flange wall that extends from the end of the flange that defines the cover opening toward the end wall (20, 22) of the housing (12).

Description

SHEET DISPENSER

TECHNICAL FIELD The present invention relates to a dispenser package for dispensing individual sheets of a limited flexibility material from a stack.

BACKGROUND OF THE INVENTION Dispenser packages for dispensing relatively thin and flexible polymeric sheet material, also known as repositionable flags, include a narrow slot in the top surface of the dispenser through which extends a top-most flag of a stack of the flags. Such a stack of flags is formed by adhering adjacent flags together along a portion of alternating opposing ends with a repositionable adhesive layer, e.g., in a Z-fold manner. As the top-most flag is withdrawn from a shuttling-type dispenser, the stack of flags moves from one end of the dispenser to the other and an end portion of the subsequent flag is folded and drawn through the narrow slot. Due to the thin and flexible characteristics of the flags, the flags are not prone to creasing as they pass through the narrow slot. The force required to withdraw individual flags that are highly flexible through the narrow slot of a shuttling-type dispenser is relatively low. While such dispensers are suitable for flexible flags, they are not suited for sheets formed of thicker and/or stiffer materials, such as polyethylene teraphthalate (PET). Sheet material formed from PET, known as index tabs, for example, is more durable than preexisting flexible flags. Durable index tabs formed of such materials are prone to creasing as they pass through the narrow slot of the dispenser. The present invention addresses the need for a low profile dispenser package that can dispense durable index tabs having reduced flexibility from a stack without excessive dispensing forces and without creasing of the index tabs.

BRIEF SUMMARY OF THE INVENTION The dispenser of the present invention comprises a base and a housing attached to the base. The housing comprises a pair of opposing side walls and a pair of opposing end walls that extend from and are generally transverse to the base, and a cover, which together define a chamber for a stack of sheets. The chamber has a length greater than that of the stack. The cover is comprised of an opening that is defined by first and second flanges. The first flange has a first end, a second end opposite the first end and a pair of opposing edges extending therebetween. The first end of the first flange is connected to a first one of the end walls of the housing. The pair of opposing edges of the first flange are adjacent to and spaced from the respective adjacent side walls. The second flange also has a first end, a second end opposite the first end and a pair of opposing edges extending therebetween. The first end of the second flange is connected to a second one of the end walls. The pair of opposing edges of the second flange are also adjacent to and spaced from the respective adjacent side walls. The second ends of each flange define a width of the opening of at least about 0.838 cm. The stack of sheets comprises a plurality of sheets, each of which has a stiffness equal to or greater than 5.756 x 10^"3 kg-cm².

BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1 is a perspective view of a dispenser package of the present invention. Fig. 2 is a top view of the dispenser package of Fig. 1. Fig. 2a is a top view of the dispenser package of Fig. 1 with a stack of index tabs therein. Fig. 3 is across-sectional view of the dispenser package of Fig. 2 taken along line 3-3. Fig. 3 a is a cross-sectional view of the dispenser package of the present invention with a stack of index tabs therein. Figs. 4-6 are cross-sectional views of the dispenser package of the present invention that depict the dispensing sequence of a index tab from a stack. While the above-identified drawing figures set forth one preferred embodiment of the invention, other embodiments are also contemplated, as noted in the discussion. In all cases, this disclosure presents the present invention by way of representation and not limitation. It should be understood that numerous other modifications and embodiments can be devised by those skilled in the art which fall within the scope and spirit of the principles of this invention. It should be specifically noted that the figures have not been drawn to scale as it has been necessary to enlarge certain portions for clarity. DETAILED DESCRIPTION A perspective view of dispenser package 10 of the present invention is shown in Fig. 1. Generally, dispenser package 10 comprises a housing 12 for containing a stack of index tabs (or "sheets"), and abase 14 connected to the housing 12. While the sheet material dispensed from the dispenser package will be referred to as "index tabs" or "durable index tabs", it should be understood that the invention contemplates the use of any sheet material formed from a variety of materials (including paper) and having a variety of thicknesses and shapes. The housing 12 is formed by injection molding a rigid polymer, such as a general purpose polystyrene, so as to form a pair of opposing side walls 16, 18, a pair of opposing end walls 20, 22, a perimeter flange 24 and a cover 26 each having a wall thickness of about

0.076 cm. Perimeter flange 24 extends from walls 16, 18, 20 and 22 adjacent to base 14 to connect housing 12 to base 14. The cover 26 is comprised of a pair of opposing flanges 28 and 30. Each of flanges 28 and 30 has one end 32 thereof connected to a respective one of the end walls 20, 22, an opposite end 34 that frames an opening 33 of cover 26, and a pair of opposing edges 36 that are spaced from the respective side walls 16, 18 so as to define an elongated slot 38 on either side of housing 12. In one representative embodiment, dispenser package 10 has a length L of about 6.93 cm and a width W of about 3.91 cm. As shown in a top view of dispenser package 10 in Figs. 2 and 2a, housing 12 defines a chamber 40 for containing a stack of durable index tabs 41 (shown partially in phantom), which in one embodiment are formed from a plurality of sheets of PET each having a sheet thickness of about 0.0091 cm. Chamber 40 has opposing ends and a length defined by a midpoint 42 of walls 20 and 22 and opposing sides and a width defined by a pair of spaced guides 43 that extend from each of the opposing sidewalls 16 and 18. In one embodiment, the stack of index tabs 41 has a length of about 3.81 cm and chamber 40 has a length of about 5.54 cm, which allows about 1.7 cm of travel for the stack 41 within chamber 40. This travel distance allows the stack to shuttle from one end of chamber 40 to the other as individual index tabs are removed from the stack. Chamber 40 has a width of about 2.64 cm, which approximates the width of the stack of index tabs. Guides 43 extend past the outermost edge 44 of each slot 38 which centers the respective side edges 46 of the index tabs within chamber 40 and prevents edges 46 from interference with outermost edge 44 as each index tab is removed from the chamber 40. As further shown in Figs. 1, 2 and 2a, each flange 28, 30 comprises an elliptical relief area 48, which is formed by an arched step down 50 that extends from end 34 of each flange substantially to second end 32 of each flange. In one embodiment, the arched step down 50 lowers the upper surface of elliptical relief area 48 by about 0.15 cm from the upper surface of adj acent area 49 of flanges 28 and 30. Elliptical relief areas 48 facilitate finger access to grab the topmost index tab from the stack and further provide structural support to each flange 28, 30 so as to restrict bending of each flange 28, 30 to the respective second ends 32 when the topmost index tab is removed from the dispenser package 10 Figs. 3 and 3a show sectional views of the dispenser package 10 taken along line 3-3 of Fig. 2. As shown in Fig. 3, flanges 28, 30 are generally parallel to base 14, which is flat.

The bottom surface of flanges 28, 30 define a height of chamber 40 of about 0.46 cm. Each end 34 of flanges 28, 30 is formed with a lip 52, which in one embodiment extends approximately 0.76 cm from base 14. By contrast, the upper surface of elliptical relief areas 48 extend only 0.51 cm from base 14. Thus, as shown in Fig. 3a, lips 52 serve to elevate the topmost index tab 54 in the stack above the elliptical reliefs 48 to allow the topmost index tab to be easily grasped for removal from dispenser package 10. As further shown in Fig. 3a, initially, the stack 41 of durable index tabs has a height closely approximating the height of chamber 40. In the disclosed embodiment, flanges 28, 30 overlap and end portion of stack41 by about .61 cm when stack 41 is positioned against the respective end walls 20, 22 of housing 12. The distance of travel of stack 41 within chamber 40 may be increased by increasing the length of chamber 40 while maintaining the length of stack 41. Alternatively, the distance of travel of stack 41 may be decreased by increasing the length of the stack 41 and maintaining the length of chamber 40. In such cases, opening 33 may also be increased by decreasing the length of each flange sufficient to maintain an overlap of about 0.61 cm of flanges 28, 30 with a respective end portion of stack 41. By ensuring that an end portion of stack 41 is overlapped by flanges 28, 30 by at least about 0.61 cm, multiple index tab dispensing during removal of a single index tab is avoided. Unintended multiple index tab dispensing is also further avoided, particularly as the index tabs in the stack are nearly depleted, by attaching the bottom-most index tab in the stack to a relatively stiff backing material. In one embodiment, the width of opening 33 of cover 26, defined by the distance between lips 52 of flanges 28 and 30, is selected to be about 0.84 cm, with opening 33 centered along the length of chamber 40. The opening 33 of cover 26 is considerably wider than the openings of shuttling-type dispensers that contain flags formed of highly flexible polymeric sheets. This wider opening 33 in cover 26 allows more space for index tabs made of thicker or more rigid polymers, such as PET, to bow and pass through opening 33 without causing a crease in the index tab. In a preferred embodiment, the width of opening 33 of cover 26 is selected to create an approximate index tab presentation angle A of about 20 degrees to about 45 degrees. It should be noted that while opening 33 is defined by lips 52 of flanges 28 and 30 in the embodiment depicted in Figs. 1, 2, 2a, and 3, in an alternate embodiment, elongate slot 38 on either side of housing could be omitted. In other words, while opening 33 would still be defined between lips 52, cover 26 would not include elongate slots 38. The operation of dispensing durable index tabs from dispenser package 10 is shown in Figs. 4-6. As shown in Fig. 4, as the top most index tab 54 is removed from the stack 41, the stack 41 slides from one end of chamber 40 to the opposite end of chamber 40. At this point, approximately one half to about three quarters of the repositionable adhesive layer 58 of topmost index tab 54 is disengaged from the subsequent index tab 60 in the stack. As shown in Fig. 5, as the topmost index tab 54 continues to be pulled, flange 28 is allowed to pivot slightly only at second end 32, due in part to the arched step down 50. As flange 28 pivots, the size of chamber 40 is increased sufficient to provide additional clearance space S for index tab 60 to be drawn through opening 33 in cover 26. Flange 28, however, continues to provide sufficient frictional resistance against index tabs 54 and 60 to prevent a premature separation of tab 54 from tab 60 as tab 54 exits chamber 40 and thus to ensure that index tab 60 is not lost within chamber 40. With the topmost index tab 54 removed from the stack 41, the subsequent index tab 60 rests on lip 52 of flange 28 for subsequent removal, as shown in Fig. 6. The dispensing force of durable index tabs (i.e., the maximum force required to remove the topmost index tab from the dispenser) was measured in a dispenser having every feature of dispenser package 10 except the elongated slots 38 that define flanges 28 and 30.

The dispensing force for the initial index tabs removed from a full stack was higher than for the remaining index tabs in the stack. The addition of the elongated slot 38 and consequent formation of flanges 28 and 30 in dispenser package 10 resulted in a normalization of the dispensing force for each index tab in the stack. In other words, the dispensing force for each index tab in the stack was generally the same. The combination of the relatively wide opening 33 and a relatively stiff flange 28 results in minimizing the dispensing force and providing a generally constant dispensing force of each durable index tab from the dispenser package 10. The width of opening 33 further ensures that index tab 60 does not become creased as it is removed from dispenser package 10. The dispenser package 10 of the present invention is particularly suited for use with relatively inflexible index tabs. The stiffness of a sheet is characterized by the tensile modulus (E) times the area moment of inertia about the principle axis (I). For sheets of PET, the tensile modulus is 3.49 X 10⁺⁶ KPa or greater. The area moment of inertia of PET index tabs having a width of about 2.54 cm and a thickness of about 0.0091 cm is 1.618 xl0^"7cm⁴. Therefore, the stiffness of such PET index tabs, (E*I), is 5.756 xlO^"3 kg-cm². Thus, in one embodiment, dispenser package 10 is adapted to dispense sheet materials that have stiffness value that is equal to or greater than 5.756 x 10^" kg-cm . The opening width of at least about 0.84 cm combined with the limited degree of flexing of flanges 28 and 30 allows the dispenser to maintain a low profile and yet ensures that relatively stiff sheets of material can be easily dispensed without creasing the sheets, and maintains a generally constant dispensing force for each sheet of material as the stack is dispensed. The dispenser package 10 is therefore useable with desktop holders designed for existing low profile dispensers of highly flexible polymer sheets that are dispensed through a narrow opening. As used herein, all numeric values expressed with two decimal places include +0.02 of the stated numeric value. Although the present invention has been described with reference to prefered embodiments, workers skilled in the art will recognize that changes may be made in form and detail without departing from the spirit and scope of the invention.

Claims

1. A dispenser for dispensing sheets of a material from a stack, the dispenser comprising: a base; a housing attached to the base, the housing comprising a pair of opposing side walls and a pair of opposing end walls extending from and generally transverse to the base, and a cover, the housing defining a chamber for the stack of sheets, the chamber having a length greater than that of the stack of sheets, wherein the cover comprises an opening defined by first and second flanges, the first flange having a first end, a second end opposite the first end and a pair of opposing edges extending therebetween, the first end of the first flange being connected to a first one of the end walls, the pair of opposing edges of the first flange being adjacent to and spaced from the respective adjacent side walls, the second' flange having a first end, a second end opposite the first end and a pair of opposing edges extending therebetween, the first end of the second flange being connected to a second one of the end walls, the pair of opposing edges of the second flange being adjacent to and spaced from the respective adjacent side walls, wherein the second ends of the first and second flange define a width of the opening of at least about 0.84 cm; and wherein the stack of sheets in the chamber of the housing comprises a plurality of sheets, each sheet having a stiffness greater than or equal to 5.756 X 10^"3 kg-cm².

2. The dispenser of claim 1 wherein each flange comprises an arched step extending from the second end of the respective flange so as to define a stepped upper surface between the first end and the second end of each respective flange.

3. The dispenser of claim 2 wherein the arched step comprises an arcuate wall extending generally transverse from the upper surface.

4. The dispenser of claim 3 wherein the arcuate wall has a height of about 0.15 cm.

5. The dispenser of claim 1 wherein each sheet in the stack is formed from PET having a sheet thickness of about 0.0091 cm.

6. The dispenser of claim 1 wherein the base comprises a flat base and wherein the first and second flanges are generally parallel to the base.

7. The dispenser of claim 1 wherein each of the first and second flanges includes an end portion adjacent to the second end of the respective first and second flanges, the end portion of one of the first and second flanges overlaping the stack by at least about 0.61 cm when the stack is in contact with one of the end walls.

8. A sheet dispenser comprising: a base; and a housing attached to the base, the housing comprising a pair of opposing side walls and a pair of opposing end walls extending from and generally transverse to the base, and a cover having an opening defined by first and second flanges, the first flange having a first end, a second end opposite the first end and a pair of opposing edges extending therebetween, the first end of the first flange being connected to a first one of the end walls, the pair of opposing edges of the first flange being adjacent to and spaced from the respective adjacent side walls, the second flange having a first end, a second end opposite the first end and a pair of opposing edges extending therebetween, the first end of the second flange being connected to a second one of the end walls, the pair of opposing edges of the second flange being adjacent to and spaced from the respective adjacent side walls, the second ends of the first and second flanges defining the opening of the cover, wherein each flange comprises a stepped upper surface between the first end and the second end of each respective flange.

9. The sheet dispenser of claim 8 wherein each flange comprises an arched step extending from the second end of the respective flange.

10. The sheet dispenser of claim 9 wherein the arched step comprises an arcuate wall extending generally transverse from the upper surface.

11. The sheet dispenser of claim 10 wherein the arcuate wall has a height of about 0.15 cm.

12. The sheet dispenser of claim 8 wherein the second end of the first flange is spaced at least about 0.84 cm from the second end of the second flange.

13. The sheet dispenser of claim 8 and further comprising a stack of sheets contained within the housing, the stack having a length less than that of the housing, wherein each sheet has a stiffness equal to or greater than 5.756 X 10^" kg-cm .

14. The sheet dispenser of claim 13 wherein the stack of sheets comprises a plurality of sheets of PET having a sheet thickness of about 0.0091 cm.

15. The sheet dispenser of claim 8 wherein the base comprises a flat base and wherein the first and second flanges are generally parallel to the base.

16. A shuttling dispenser for dispensing sheets of a material from a stack, the dispenser comprising: a flat base; a housing attached to the base, the housing comprising a pair of opposing side walls and a pair of opposing end walls extending from and generally transverse to the base, and a cover, the housing defining a chamber for the stack of sheets, the chamber having a length greater than that of the stack of sheets and a height closely approximating that of a full stack of sheets, wherein the cover comprises an opening defined by first and second flanges, the first and second flanges being generally parallel to the base, the first flange having a first end, a second end opposite the first end and a pair of opposing edges extending therebetween, the first end of the first flange being connected to a first one of the end walls, the pair of opposing edges of the first flange being adjacent to and spaced from the respective adjacent side walls, the second flange having a first end, a second end opposite the first end and a pair of opposing edges extending therebetween, the first end of the second flange being connected to a second one of the end walls, the pair of opposing edges of the second flange being adj acent to and spaced from the respective adjacent side walls, wherein the second ends of the first and second flange define a width of the opening of at least about 0.84 cm; and wherein the stack of sheets in the chamber of the housing comprises a plurality of sheets, each sheet having a stiffness greater than or equal to 5.756 X 10^"3 kg-cm².

17. The dispenser of claim 16 wherein each flange comprises an arched step extending from the second end of the respective flange so as to define a stepped upper surface between the first end and the second end of each respective flange.

18. The dispenser of claim 17 wherein the arched step comprises an arcuate wall extending generally transverse from the upper surface.

19. The dispenser of claim 18 wherein the arcuate wall has a height of about

0.06 inches.

20. The dispenser of claim 16 wherein each of the first and second flanges includes an an end portion adjacent to the second end of the respective first and second flanges, the end portion of one of the first and second flanges overlaping the stack by at least about 0.61 cm when the stack is in contact with one of the end walls.