US20040217540A1

US20040217540A1 - Apparatus and method for dispensing sheets

Info

Publication number: US20040217540A1
Application number: US10/481,308
Authority: US
Inventors: Dan Sinai; Daniel Granot
Original assignee: SIRODAN TECHNOLOGIES Ltd
Current assignee: SIRODAN TECHNOLOGIES Ltd
Priority date: 2001-06-20
Filing date: 2002-06-19
Publication date: 2004-11-04
Also published as: TW574122B; WO2002102692A1; IL143894A0

Abstract

Apparatus and method for dispensing individual sheets from a stack of sheets (10). A support (30) is provided for accommodating the stack of sheets in overlying parallel relationship. A suitable pickup device (20) overlying the support and having blowing means (62) is provided for producing airstreams over one end (A) of the upper sheet of the stack, such as to curl up this end and separate a portion of the upper sheet including this end from the stack. The pickup device also provides a holding force (60, 66), typically in the form of a suction force (60, 66) such as to hold at least part of this portion abutted against said pickup device, whereupon the airstreams may be terminated. A peeling mechanism (50) is also provided, having a clamping mechanism (70) for clamping the separated portion of the upper sheet, and adapted for displacing at least part of the sheet in a peeling motion in a direction substantially away from the original position of the end and/or the stack.

Description

FIELD OF THE INVENTION

The present invention relates generally to apparatus and associated method for the feeding of sheets, and more specifically for the dispensing of sheets from a stack thereof. In particular, the present invention is concerned with feeding and manipulation of sheets made from limp and/or porous materials, including fabrics and paper, which may be optionally impregnated with a liquid material, such that only a single sheet is dispensed from the stack at a time in a reliable manner and in a manner which prevents or at least significantly reduces the possibility of more than one sheet being dispensed during a single dispensing action, and which further minimizes the production and ejection of particles from the sheets into the atmosphere.

BACKGROUND OF THE INVENTION

The automated feeding or dispensing of sheets of soft paper or fabric presents some difficulty, generally because the softness or limpness of the material, their tendency to adhere one to another, their roughness and compressibility. The difficulties increase when dealing with porous and/or impregnated materials.

Particularly with reference to the semiconductor industry, where it is vital to clean items in a room such as machinery or furniture, or items entering the clean room such as user's goggles, for example, the dispensing of fabric wipes used for such cleaning presents a particular problem. As a sheet (or a bunch thereof) is pulled by a user, the frictional action between the grasped sheet(s) and the remaining sheets as a result of the shearing forces therebetween produces small and even microscopic fragments or particles of fabric that tear off the sheets and are expelled into the air. These fragments are potentially very destructive in this industry, and the dispensation of the sheets to a user must be such as to minimise the production and dispersal of fabric particles or fragments into the atmosphere of the clean room. Automatic dispensers in which an upper sheet is dragged with respect to a stack of sheets is thus clearly unacceptable. Similarly, providing a system of folded intercalated sheets, in which as an upper sheet is pulled out from a box thereof, a second sheet is partially pulled out for easier user access thereto is also unacceptable. In such a system, the fold in each sheet produces particles, and the pulling action also induces shear forces between adjacent sheets which further produces and expels particles. A system comprising a spool or roll of material from which a length of sheet may be removed and cut off as required by a user is also not acceptable. In such a system, the cutting process also produces and disperses particles into the air.

Furthermore, it is sometimes required in the clean rooms to impregnate the sheets with alcohol to assist in the cleaning process, and to finish the process with a dry wipe. Typically, either pre-impregnated or “saturated” wipes are used, or dry wipes are sprayed manually with alcohol. The first option requires two sets of wipes to be readily available, one dry, and the other “saturated”, which has repercussions in the supply logistics. The second option results in a great deal of excess alcohol being sprayed onto the surrounding environment and thus also into the atmosphere of the clean room. The latter option thus increases the levels of VOC (Volatile Organic Chemicals), which should be avoided.

Thus, in such applications as in the semiconductor industry, the solution has been until now to manually dispense the towels or wipes, wherein a user grasps the sheets from a stack enclosed in a container or a pouch via an opening therein. Such an operation on average results in more than one sheet being grasped with each grabbing action. With pretreated or impregnated towels, such wastage can have significant economic repercussions. Nevertheless, in clean rooms of the microchip industry as well as medical and/or surgical wards, and the like, where high quality and expensive towels particularly impregnated with cleaning solutions are routinely needed, the user is typically wearing gloves, which increases the difficulty in taking only a single towel at a time, and the capability of dispensing of towels one at a time presents an economic advantage.

In the clothing manufacturing industry, there is also a need for manipulating and dispensing standard sized and shaped pieces of cloth or other fabric. There is also a need to enable soft sheets to be automatically provided to a user on demand, in a simple and reliable manner.

The problem of automatic feeding of sheet material, particularly fabrics, leather and other limp materials, and to a lesser extent paper, is discussed in U.S. Pat. No. 4,635,917, U.S. Pat. No. 4,708,333 and U.S. Pat. No. 4,703,926. In U.S. Pat. No. 4,635,917, a method and apparatus for feeding sheets is described for feeding fabrics from a stack, comprising an arrangement for: engaging the opposite edges of the upper sheet of the stack by a pair of restrainer members; bringing a pickup head into engagement with the upper sheet of the stack while producing airstreams from the pick-up head directed outwardly across opposite edges of the upper sheet of the stack; lowering the pick-up head to depress the stack below the restrainer members whereby the airstreams cause the opposite edges of the upper sheet of the stack to curl upwardly to clear the restrainer members; lifting the upper sheet from the stack; permitting the stack to rise so as to bring the next sheet into engagement with the restrainer members, whereupon the stack is ready for feeding the next upper sheet. Thus, the intention is for the upper sheet to be removed vertically from the stack by virtue of the lifting action of the airstreams, coupled with the vertical movement of the pick-up head. There are two main problems associated with this arrangement. First, the airstreams, while providing initial separation of the ends of the upper sheet, are not inherently suitable for maintaining a hold on the ends of the sheet, which may then fall. This is exacerbated by the second problem. The airstreams only lift up the ends of the sheet, but not the intermediate portion of the sheet. Thus, the action of vertically lifting the upper sheet may not be entirely successful in separating the intermediate portion of the sheet from the next sheet. Any adhesion or friction between the upper sheet and the next sheet provides a resistance to the lifting action, and either more than one sheet is thus lifted with the upper sheet from the stack, or more likely, the lower sheets act as an anchor, effectively pulling down on the upper sheet, causing the ends thereof to be distanced from the airstreams and reducing their effectiveness, thereby resulting in a catastrophic disengagement of the upper sheet from the pick-up head. In U.S. Pat. No. 4,708,333, additional airstreams are provided from outside the stack and directed towards it to aid in the separation of the top sheet by the pick-up head. Nonetheless, the arrangements are also subject to the two problems discussed above. U.S. Pat. No. 4,703,926, assigned to the same assignee as the other two patents, is directed in particular to an edge aligning device, and does not address these problems.

An aim of the present invention is to provide an apparatus and method for feeding or dispensing sheets that overcomes the disadvantages of prior art feeding apparatuses and methods.

It is another aim of the present invention to provide an apparatus and method for feeding or dispensing sheets from a stack, particularly adapted for sheets made from soft and/or limp and/or porous materials.

It is another aim of the present invention to provide such an apparatus and method for reliably dispensing a single sheet with each dispensing action.

It is another aim of the present invention to provide such an apparatus and method in which the sheets may be individually impregnated with a desired liquid prior to dispensing.

It is another aim of the present invention to provide such an apparatus and method wherein the various steps involved in the dispensing of a sheet thereby may be individually controlled.

It is another aim of the present invention to provide such an apparatus, in which the dispensing of sheets is conducted in a particularly clean manner, minimising or eliminating the ejection of fabric particles or fragments from the sheets

It is another aim of the present invention to provide such an apparatus particularly adapted for use in clean rooms such as of the semiconductor industry and operating theaters, for example.

Other purposes and advantages of the invention will appear as the description proceeds.

SUMMARY OF THE INVENTION

The present invention relates to an apparatus for dispensing sheets comprising:

(a) a support for accommodating a stack of sheets in overlying parallel relationship;

(b) a pickup device overlying said support and comprising suitable blowing means, typically in the form of air openings, for producing airstreams over a first end of the upper sheet of the stack that may be accommodated by said support, such as to curl up said end and separate a portion of said upper sheet including said end from the stack, and further comprising suitable suction means, typically in the form of apertures, for creating a suction force such as to hold at least part of said portion abutted against said pickup device;

(c) a peeling or peel-back mechanism having a clamping mechanism for clamping the separated portion of the upper sheet and adapted for displacing at least a part of the sheet in a peeling motion with respect to a remainder of said stack that may be accommodated by said support, typically in a direction substantially away from said end and typically towards a second end of the sheets in longitudinally opposed relationship to said first end.

In the preferred embodiment, the pickup head comprises a displacement arrangement for reciprocally moving said pickup device towards and away from the stack that may be accommodated by the tray. The displacement arrangement is adapted for providing vertical as well as horizontal motion to said pickup device. The pickup head may be configured to reciprocally rotate about a suitable axis such as to provide a desired vertical and horizontal movement to a part of said pickup head, wherein said part of said pickup head comprises said blowing means and said holding means. The displacement arrangement may comprise a piston driver that is electrically actuable and controllable by any suitable control means including suitable electric, electronic or computer means.

The holding means typically comprise suction means, and this may comprise a cylindrical member having suitable apertures operatively connected to a suitable suction source, said cylindrical member being substantially aligned with said end. The blowing means typically comprise suitable openings provided in a plenum chamber accommodated in said pick up head, said openings being operatively connected to a suitable compressed gas or air source, such as an air compressor arrangement or air blower for example, such as to provide substantially tangential airstreams with respect to said cylindrical member.

The suction means and the blowing means may be operatively interconnected, and may be incorporated in a fan or air blower arrangement, wherein suction is provided by the inlet to the air blower, and airstreams by the outlet thereof.

The air compressor arrangement is preferably electrically actuable and controllable by any suitable control means including electric, electronic or computer means.

The apertures are typically operatively connected to a suitable vacuum source, such as for example a suitable vacuum pump, ejector or suction pump arrangement. Preferably, the pump arrangement is electrically actuable and controllable by any suitable control means, including electric, electronic or computer means.

The clamping mechanism typically comprises a support member having clamping means at each end thereof adapted for clamping said separated portion of said upper sheet, and a pair of arms substantially orthogonal to said support member pivotally mounted with respect to a suitable swinging axis. The clamping means may comprise jaws, for example, or a substantially stationary clamping member adapted for clamping with respect to the cylinder after the pick up head separates and holds one end of the sheet. Preferably, the clamping means or jaws are electrically actuable and controllable by any suitable control means, including electric, electronic or computer means. The clamping mechanism is optionally displaceable, preferably via a swinging motion, by means of a suitable driving mechanism, which is preferably electrically actuable and controllable by any suitable control means, including electric, electronic or computer means.

The peeling or peel-back mechanism is preferably suitably synchronised with said pickup device. The synchronization between the pick up head and the peeling mechanism may be provided by suitable mechanical means and/or other suitable synchronization means including electrical, electronic, or computer means.

The tray is preferably a horizontal tray, and preferably in horizontal alignment and reversibly movable from a position outside the apparatus to a position inside the apparatus.

The apparatus preferably further comprises optional suitable spraying system for spraying at least one suitable liquid to a said sheet, said spraying system being operatively connected to at least one source of said liquids and comprising at least one nozzle adapted for spraying said at least one liquid. The spraying system may be adapted for spraying a said sheet after the sheet has been fully separated from the said stack, and is preferably synchronised with at least with said peeling system.

The synchronisations may be provided by suitable mechanical means, such as for example including suitable mechanical linkage between said pickup device and said peeling mechanism. Preferably, such synchronisations are provided by suitable synchronization means, including electrical, electronic or computer means.

Optionally, the spraying system further comprises suitable means for enabling any desired combination of said liquids to be sprayed in any desired relative proportions onto said sheet.

The spraying system may be operatively connected to the blowing means, wherein the blowing means generate suitable airstreams to carry the liquid spray to the sheet. Preferably, such a spraying system may be suitably synchronized with the blowing means such as to enable a sheet to be sprayed after the sheet has been at least partially or fully separated from the stack.

Optionally, the holding means constitute said clamping mechanism. Optionally, the peeling mechanism is incorporated in said pick up head, and the peeling mechanism may include suitable means for swinging the pickup head with respect to the stack.

The present invention also relates to corresponding methods for dispensing sheets from a stack of sheets in overlying substantially parallel relationship, comprising:

(a) providing suitable airstreams over a first end of the upper sheet of the stack such as to curl up said first end and separate a portion of said upper sheet including said first end from the stack;

(b) creating a suitable holding force such as to hold said first end abutted against a suitable pickup device, and terminating the said airstreams;

(c) clamping the separated portion of the upper sheet in (b) and terminating the suction force;

(d) displacing the sheet by a peeling or peel-back motion with respect to a remainder of the stack, typically in a direction substantially towards a second end of said upper sheet opposed to said first end.

Said first end and/or said second end may each comprise a corner or an edge of the sheet, for example, or indeed any other part of the sheet, as required or desired.

Typically, the holding force comprises a suction force. Optionally, all of said sheet is displaced in a peeling motion from said stack. Alternatively, part of the sheet is displaced in a peeling motion from the stack, and a remaining part of said sheet which is still in overlying relationship with said stack is removed from the stack by providing a force to the sheet in a direction substantially towards said first end. This force may be provided by generating suitable airstreams to impinge on said sheet.

The said first end comprises an edge or a corner of said sheet.

The method may further comprise the step (e) of impregnating the separated sheet with a suitable liquid after the sheet has been separated, and/or the step (f) of releasing the separated sheet for collection or further processing.

Step (a) may be effected by lowering a suitable pickup device until it rests gently on said upper sheet, said blowing means comprising a cylindrical member having suitable openings for providing said airstreams. The suction force in step (b) may be provided via suitable apertures in said pickup device operatively connected to a suitable vacuum source. Step (c) may be effected by means of a suitable peeling mechanism including a clamping mechanism having a pair of opposed clamping members, typically jaws, adapted for clamping said separated portion of said upper sheet, and a pair of arms extending orthogonally from said jaws and pivotally mounted with respect to a suitable swinging axis. Step (e) may be effected by means of a spraying system adapted for spraying said liquid to the separated sheet.

Preferably, steps (a) to (d) are synchronised with respect to one another, and further preferably, at least steps (d) to (e) are suitably synchronised with respect to one another. Steps (a) to (d) may be at least partially synchronised by any suitable mechanical means, which may include suitable mechanical linkage between said pickup device and said peeling mechanism. Alternatively, the synchronisation is provided by suitable synchronization means, including electrical, electronic or computer means.

BRIEF DESCRIPTION OF THE FIGURES

FIG. 1 illustrates, in cross-sectional side view, the main elements of a first embodiment of the present invention in the dispensing position. [0044]
FIG. 2 illustrates, in front perspective view, the embodiment of FIG. 1. [0045]
FIG. 3 illustrates, in rear perspective view, the embodiment of FIG. 1. [0046]
FIG. 4 illustrates, in cross-sectional side view, the main elements of a first embodiment of the present invention in the clamping position. [0047]
FIG. 5 illustrates, in front perspective view, the embodiment of FIG. 4. [0048]
FIG. 6 illustrates, in rear perspective view, the embodiment of FIG. 4. [0049]
FIGS. [0050] 7(a) to 7(h) illustrate schematically the operation of the first embodiment of the present invention.
FIG. 8 illustrates, in cross-sectional side view, the main elements of a second embodiment of the present invention. [0051]
FIG. 9 illustrates, in bottom perspective view, the embodiment of FIG. 8. [0052]
FIG. 10 illustrates, in cross-sectional upper view, the embodiment of FIG. 8 taken along A-A. [0053]
FIG. 11 illustrates, in top view, the embodiment of FIG. 8. [0054]
FIG. 12 illustrates, in cross-sectional side view, the embodiment of FIG. 11 taken along B-B. [0055]
FIGS. [0056] 13(a) to 13(d) illustrate schematically the operation of the second embodiment of the present invention.

DESCRIPTION

The present invention is defined by the claims, the contents of which are to be read as included within the disclosure of the specification, and will now be described by way of example with reference to the accompanying Figures. [0057]
The present invention relates to an apparatus and corresponding method for dispensing single sheets of a typically limp and/or porous material from a stack thereof. Such sheets may be made from paper, fabric, leather or the like including towels, wipes and so on. The present invention is characterised in that the sheets are each in turn grasped close to one free end, such as an edge or corner, thereof and peeled away from the stack in a direction substantially perpendicular to where this free end was, i.e., in a direction towards a second end which is in opposed relationship longitudinally from the first, grasped end. In other words, the sheet is peeled back from the free end in a manner such as not to substantially introduce shear forces between the sheet and the adjacent sheet or surface below it, thereby minimising the possibility of more sheets being removed together with the uppermost sheet, and thus minimising both wastage and the generation of microscopic fibers and the like. Thus a “peeling” or “peel-back” motion is herein understood broadly as a motion by a sheet such that as successive adjacent portions of a first (or upper) sheet are progressively separated from an adjacent second sheet or other surface below the first sheet, the remaining portions of the first sheet are still substantially in contact with the second sheet or surface, wherein such contact does not induce substantial sliding, shear or adhesive forces due to the peeling motion. By substantial sliding shear or adhesive forces is meant that such forces do not result in the creation of particles from the sheet in quantities or concentrations greater than a desired threshold value. Such a threshold value generally depends on the application for the apparatus of the invention, and thus where a higher level of cleanliness is required, the threshold value will be less, and conversely, where the level of cleanliness may be relaxed, a greater amount of relative sliding motion between sheets may be tolerated. Generally, such peeling motions involve a degree of motion by one end (edge or corner, for example) of the sheet towards the opposite edge of the sheet, with possibly some degree of folding of the sheet over itself, while typically at the opposite end of the sheet there is little or no substantial relative motion between the uppermost sheet and the sheets below it until the last moment when the end of the uppermost sheet is fully peeled form the stack of sheets. Accordingly, such a peeling motion substantially reduces or removes the formation and expulsion into the atmosphere of sheet fragments and particles. In some cases though, the peeling motion may be provided for part of the length of the sheet, and the last part of the sheet separated from the next sheet in a different manner, as will be further described hereinbelow. [0058]
The present invention thus relates to an apparatus for dispensing sheets comprising: [0059]
a support for accommodating a stack of sheets in overlying parallel relationship; [0060]
a pickup device overlying said support and comprising suitable blowing means, typically in the form of first air openings, for producing airstreams over one end, including an edge or corner, for example, of the upper sheet of the stack such as to curl up said end and separate said end from the stack, and further comprising suitable suction means or the like, typically in the form of apertures connected to a suction or vacuum source, for creating a suction force such as to hold said end abutted against said pickup device; and [0061]
a peeling mechanism having a clamping mechanism for clamping the separated portion of the upper sheet and adapted for displacing at least part or all of the sheet in a peeling motion with respect to a remainder of said stack that may be accommodated by said support, typically in a direction substantially away from said end, that is, towards an opposed end of the sheet. [0062]
Thus, referring to the figures, in particular FIGS. [0063] 1 to 6, a first embodiment of the dispensing apparatus according to the present invention is generally indicated at (100) and comprises a suitable housing (200) (shown schematically as a dotted line in FIGS. 1 and 4) adapted for accommodating a pickup device (20), a peeling mechanism (50), and a support in the form of a horizontal tray (30) for holding a stack of sheets (10). Each said sheet (10) is typically rectangular having a first free edge (A) and a second free edge (B) in parallel opposed relationship, and orthogonal thereto third and fourth edges (C) and (D), with corners between adjacent edges. In some embodiments, the sheets may be in any other desired shape, wherein the apparatus (100) is correspondingly adapted for these shapes, typically in that the tray (30) comprises a suitable shape for accommodating the sheets and/or in that the pickup device (20) having suction means and blowing means where necessary to pick up a desired end of the sheets, and/or in that the peeling mechanism (50) is suited for clamping the raised part of the sheets, typically in a manner similar to that described herein with respect to sheets (10), mutatis mutandis. The sheets (10) may be made from any type of flexible and/or limp and particularly, but not limited to porous material, including paper tissue paper, flexible plastic, fabric, leather. The sheets may also be optionally pre-impregnated with a suitable liquid, such as alcohol, detergent, soap, disinfectant, for example, or may be individually sprayable with any suitable liquid just before delivery to the user.
The tray ([0064] 30) is typically horizontal and sheets can be vertically stacked thereon in horizontal arrangement. In other embodiments the tray may be adapted to accommodate sheets in vertical arrangement or indeed in any inclined arrangement, in a similar manner to the horizontal arrangement, mutatis mutandis. In the first embodiment, the tray (30) has an upper open end and is slidable or otherwise moveable, typically in a substantially horizontal direction, from a position outside the housing (200), wherein the tray (30) may be replenished with a stack of generally horizontally-laid overlying sheets (10) as required, to a position inside the housing (200), generally below the pickup device (20) and peeling mechanism (50). The tray (30) preferably comprises an internal floating bottom end that is urged upwards via springs or the like, such as to move the stack of sheets (10) in an upward direction to compensate for the decrease in height of the stack as sheets (10) are progressively dispensed thereof by the apparatus (100). Thus, the uppermost sheet (10′) of the stack is preferably maintained at generally the same position with respect to the housing (200), regardless of the number of sheets (10) remaining in the stack. Other mechanisms are known in the art for elevating the upper end of the stack with respect to a suitable point in the housing and do not need to be further described herein. Where the apparatus (100) does not comprise such a height-maintaining mechanism for the stack of sheets (10), the apparatus (100) may instead compensate for the increasing depth location of the uppermost sheet (10′) as the stack is used up. Such compensation mechanisms are known in the art for progressively lowering the pick-up head with respect to the upper end of the stack and do not need to be further described herein
The pickup device ([0065] 20) comprises a displacement arrangement for displacing a pick up head (22) in relation to the stack of sheets, As is further described below, the displacement arrangement in this embodiment provides reciprocating and primarily vertical motion to the pickup head (22), enabling the same to be alternately raised from and lowered to the stack of sheets (10). In other embodiments, the pickup device may comprise a displacement arrangement that provides a rotational motion to the pickup device such that a part of the pickup device can be vertically and horizontally moved as required.
In the first embodiment, the displacement arrangement is in the form of a piston drive ([0066] 40) having a lower free end (42) connected to said pick-up head (22), and an upper end (44) anchored to a fixed point (110) in the housing (200). Referring in particular to FIGS. 1, 4 and 7(a) to 7(d), the pickup head (22) comprises a pad member (24) and a cylindrical member (60) connected thereto, which are arranged for gently resting on or close to the upper sheet (10′) of the stack of sheets (10) when the pickup device (20) is lowered thereonto. The cylindrical member (60) is aligned such that its longitudinal axis is substantially parallel to and orthogonally displaced from the first free edge (A) of the upper sheet (10′). The said cylindrical member (60) is typically a little shorter than the width of the sheets (10), as defined by the spacing between edges (C) and (D) thereof.
The pickup head comprises suitable blowing means for generating at least one suitable airstream over the upper sheet during operation of the head. The blowing means is typically in the form of nozzles or the like operatively connected to a suitable compressed gas source, which is typically a compressed air source including, for example, compressed air bottles or a suitable air compressor such as a fan or air blower, for example. Thus, in the first embodiment, the pad member ([0067] 24) is substantially hollow with closed longitudinal ends, and thus forms a plenum chamber (21) which is connectable to a source of pressurised air. The plenum chamber (21) comprises a longitudinal slit, or preferably a series of slits, nozzles or openings (62) in spaced arrangement along its length. The openings (62) provide a series of airstreams along the upper surface of the upper sheet (10′) of the stack in a direction towards the edge (A), when the pickup head (22) is resting on sheet (10′), and tangential to the cylindrical member (60). The effect of providing this series of airstreams is to curl up the free end (A′) that comprises the said edge (A) of the upper sheet (10′) in an upward direction towards the cylindrical member (60), and thus separate this end (A′) of the upper sheet (10′) from the next sheet (10) directly below it, as illustrated in FIG. 7(b). As the airstreams follow the upwardly curving surface of the cylindrical member (60), a lifting effect is created with respect to the end (A′) of sheet (10′). A suitable compressed gas or air source (not shown) is thus operatively connected to the pad member (24) to provide the airstreams.
The pickup head is characterized in further comprising a suitable holding means for temporarily adhering the lifted end of the upper sheet to the pickup head after the end has been separated from the stack by means of the blowing means. The holding means are preferably in the form of suction means. Thus, the cylindrical member ([0068] 60) typically comprises a series of apertures (66) in spaced arrangement along its length. The series of apertures (66) are operatively connected to a suitable vacuum source (not shown) and are typically positioned at the lower part of the cylindrical member (60), or close to the bottom and preferably displaced to the right as viewed in Fig. 1. The location of the apertures (66) and the strength of the suction provided thereat by the suction source is such as to suck the free end (A′) towards the cylindrical member (60) after the end (A′) has been curled up by means of the aforesaid airstreams, and to then hold the upper sheet (10′) firmly against the cylindrical member (60) via this end (A′), as illustrated in FIG. 7(c). At this point, while suction is maintained via said apertures (66), the airstreams provided via openings (62) are terminated. Thus, in the normal course of events, the end (A′) is maintained firmly abutted against the cylindrical member (60) until the suction to the apertures (66) is terminated. The piston drive (40) then lifts the pickup head (22), separating a larger portion (X) of the upper sheet (10′) from the stack, as illustrated in FIG. 7(d). At the same time, a concurrent horizontal motion is also provided by the piston drive (40) in a direction towards the edge (B) such as to prevent the upper sheet (10′) being dragged in the opposite direction by virtue of the lifting action via edge (A), which could otherwise crumple the upper sheet (10′) and/or cause adhesion or other interference with lower sheets (10). In other embodiments, rather than employing suction to hold the upper sheet (10′) with respect to the pick up device (20), the apparatus (100) may alternatively comprise any suitable means for holding the upper sheet (10′), such means including any suitable mechanical means such clamping means or grasping means, for example.
While the beginning of the peeling action by means of the pick-up head, i.e., the separation stage of the process where an end of the sheet is separated from the stack, has been described above with respect to one edge (A) of the sheet, the sheets may be picked up and peeled from any suitable end of the sheet. For example, the sheets may be oriented such that a corner thereof, rather than an edge thereof, is aligned with respect to the pickup head ([0069] 20). Thus, the air openings (62) may provide a series of airstreams along the upper surface of the upper sheet (10′) of the stack in a direction towards this corner (A), when the pickup head (22) is resting on sheet (10′), curling up this free corner in an upward direction towards the cylindrical member (60), thus separating this corner of the upper sheet (10′) from the next sheet (10) directly below it. As the airstreams follow the upwardly curving surface of the cylindrical member (60), a lifting effect is created with respect to the end of sheet (10′) that comprises this corner. As before, this free corner is then sucked towards the cylindrical member (60), and the upper sheet (10′) is firmly against the cylindrical member (60) via this corner. At this point, while suction is maintained via said apertures (66), the airstreams provided via openings (62) are terminated. Thus, in the normal course of events, the corner is maintained firmly abutted against the cylindrical member (60) until the suction to the apertures (66) is terminated and the pickup head continues as described before, mutatis mutandis. Similarly, round or oval sheets, or indeed sheets of any shape may be picked up in a similar manner as described above, mutatis mutandis, by first blowing airstreams over one end, and then sucking or otherwise holding the end in abutment with the cylindrical member (60).
Referring in particular to FIGS. [0070] 7(e) to 7(h), the peeling mechanism (50) is characterised in having means for grasping or clamping the end (A′) after this has been separated from the stack of sheets (10), and in then progressively separating the upper sheet (10′) from the stack in a peeling motion, typically, or at least in part, in a general direction towards the opposite free end or edge (B) of the sheet (10′). This type of relative movement between the upper sheet (10′) and the stack introduces substantially no tendency for sliding between the upper sheet (10′) and the next sheet (10) directly below it, thereby generally ensuring that no additional sheets (10) are removed together with the upper sheet (10′). The peeling action provided by the peeling mechanism (50) comprises primarily a substantially horizontal displacement of the free end (A′) in a direction towards the second free edge (B), such that virtually no shearing forces are introduced between the upper sheet (10′) and the sheets (10) below it, which would otherwise stick thereto due to frictional forces thereby set up. Furthermore, it is often encountered in a stack of sheets that adjacent sheets (10) stick to each other because of electrostatic attraction, or due to any other effect. In the present invention, the peeling motion provided by the peeling mechanism “unsticks” the upper sheet (10′) from the adjacent sheet (10) thereto once the free end (A) of the upper sheet (10′) has been successfully separated form the stack by means of the pickup device (20). Furthermore, this peeling motion also prevents or at least substantially reduces the production of particles or fragments from the material of the sheets.
The piston drive ([0071] 40) may be pneumatically or hydraulically operated. Alternatively, and preferably, the required motion to the pickup head (22) is provided by any suitable electrically actuated arrangement, which may be controlled by any suitable electric, electronic or computer means. Similarly, the airstreams and vacuum provided by means of openings (62) and apertures (66), respectively, may be provided by a suitable gas source and vacuum source, respectively, but are preferably provided by means of electrically operated suitable compressors (including air blowers or fans) and vacuum pumps, respectively, which may be controlled by any suitable electric, electronic or computer means.
Alternatively, the piston drive ([0072] 40) may be replaced by any suitable mechanical mechanism capable of providing the require motions to the pick up head (22), and such mechanisms are known. In particular such a mechanical mechanism is actuable electrically and controllable by any suitable electric, electronic or computer means, to provide a more compact apparatus (100).
In the first embodiment, the peeling mechanism ([0073] 50) comprises a clamping mechanism (70) which is reciprocally movable between a first, dispensing position (DP) to a second, clamping position (CP), illustrated in FIGS. 1 and 4 respectively. The clamping mechanism (70) is adapted to clamp the upper sheet (10′) along the edges (C) and (D), in particular of the portion (X), once this portion of the upper sheet (10′) has been separated and lifted by means of the pickup device (20), described hereinbefore. Of course, where the sheets (10) are or a different shape, or indeed oriented such as to present a corner rather than an edge with respect to the cylindrical member (60), the clamping mechanism (70) is adapted for clamping lateral portions of the sheets, wherein said lateral portions are typically in orthogonal relationship to said end of the sheets that is picked up via the pickup device (20). In the first embodiment of the present invention, and referring particularly to FIGS. 1, 3 and 4, the clamping mechanism (70) comprises a pair of clamping jaws (72), one said clamping jaw (72) being accommodated at each of the ends of a support bar (73). The support bar (73) comprises a suitable actuation mechanism (74), which may include for example an electrical actuator including a solenoid, or a hydraulic, pneumatic or other suitable actuator, enabling the jaws (72) to selectively and alternately open or close against the support bar (73). The support bar (73) is in a generally parallel juxtaposed and spaced relationship with respect to the said cylindrical member (60). The support bar (73) is somewhat longer than the width of the sheets (10), and thus the ends of the support bar (73) extend beyond the edges (C) and (D) of the upper sheet (10′). The support bar (73) is joined at its ends to two spaced parallel C-shaped arms (75), which are rotatably mounted to a shaft (80), which is substantially parallel to the support bar (73). The shaft (80) is fixed in the housing (200), and enables the support bar (73) to be rotated with respect thereto about axis (82) of the shaft (80) via arms (75), such as to displace the support bar (73) vertically and horizontally between the said dispensing position (DP) and the said clamping position (CP).
Referring particularly to FIGS. 4 and 7([0074] e) to 7(h), in the said clamping position (CP), the support bar (73) is located to the right of the portion (X) of the upper sheet (10′) (as viewed in FIG. 4), such that the jaws (72) in the open position are to the left of portion (X). Thus, when the jaws (72) are closed, they grip portion (X) of the upper sheet (10′) against the support bar (73). After the clamping mechanism (70) clamps the upper sheet (10′), the pickup device (20) may disengage from the end (A′), typically by terminating suction at the apertures (66).
As the support bar ([0075] 73) swings via a suitable driver (not shown) from the clamping position (CP) to the dispensing position (DP) about axis (82), the support bar (73) undergoes a net horizontal displacement in a direction towards the second free edge (B) of the upper sheet (10′), thereby causing the upper sheet (10′) to initially substantially fold over itself and thus peel away from the adjacent sheet (10) until the said upper sheet (10′) is fully displaced horizontally from its adjacent sheet (10), which of course is now upper in the stack. At the same time, the support bar (73) also undergoes a net vertical displacement in the upward direction such that the edge (B) is now hanging below the support bar (73), and a sheet in this position is illustrated in FIGS. 1 and 7(h) as sheet (10″). Thus, at the dispensing position (DP), the previously upper sheet (10′) is completely removed from the stack and is hanging, by means of the clamping mechanism (70), over a collection trough (90), as indicated at (10″) in FIGS. 1 and 7(h). At this point, the actuation mechanism (74) is disengaged, and this sheet (10″) falls by gravity into the trough (90). The trough (90) is in open communication with the outside of the housing (200) via a suitable opening (95), enabling a user to access the sheet thus dispensed. Alternatively, the hanging sheet (10″) may be further manipulated by suitable mechanisms is so required.
In other embodiments, the peeling mechanism ([0076] 50) may comprise any other suitable means for providing the required peeling motion to the sheet (10′) by grasping or clamping the separated end (A′) thereof. For example, in place of the clamping mechanism (70) described herein, the peeling mechanism (50) may comprise a pair of belts driven by suitable drive means, the belts being located one on either side of the sheet (10′), parallel to edges (C) and (D) respectively. The belts may each comprise one or more grasping or clamping jaws, and comprise a path of revolution such that one jaw on each belt is synchronised to clamp portion (X) of the sheet (10′) along edges (C) and (D), and to then peel the sheet (10′) to the dispensing position (DP) in an appropriate manner.
The peeling mechanism ([0077] 50) may be pneumatically or hydraulically operated. Alternatively, and preferably, the required motion to the clamping mechanism (70) including the jaws (72) is provided by any suitable electrically actuated arrangement, which may be controlled by any suitable electric, electronic or computer means.
While the sheet ([0078] 10″) is hanging in the dispensing position (DP), optional spraying system (300) may be provided for spraying a suitable liquid onto the sheet (10″) just before being dropped into the trough (90). Such spraying system (300) may be advantageous in cases, for example, where it is desired to dispense disinfectant-impregnated hand-towels, wipes impregnated with cleaning solutions including for example alcohol, or the like, in particular where the liquid is volatile and thus evaporates relatively quickly from the sheet, rendering pre-impregnated sheets unsuitable. The spraying system (300) is preferably operatively connected to a suitable electric, electronic or computer controller. The spraying system (300) may be adapted for automatically spraying each sheet (10″) just before being dispensed. Alternatively, a manual interaction facility may be incorporated into the spraying system (300) to enable the user to spray any particular sheet (10″) as desired. Alternatively, the spraying system (300) may be controlled such as to spray a number of sheets in succession, and then to desist from spraying for another succession of sheets, for any desired frequency and permutation of sprayed sheets and dry sheets, according, by suitably programming a computer control means operatively connected to the spraying system (300).
The spraying system ([0079] 300) may comprise one or more spraying nozzles (350) in communication with one or more suitable liquid sources (not shown) that it is desired to spray onto the sheets. Suitable control means may also be provided for enabling the user to choose any one of a plurality of such liquids to be sprayed onto the sheet (10″). Optionally, such control means may also enable the user to mix two or more such liquids via dedicated or shared nozzles (350) in any desired quantities or proportions. Thus, for example, the spraying system (300) may comprise a nozzle (350) operatively connected to a source of alcohol, and another nozzle (350) operatively connected to a source of deionised or distilled water. Electrically operated valves, for example, may then be used, in conjunction with a controller, to enable either water or alcohol, or indeed any mixture of the two, to be sprayed onto the hanging sheet (10″), according to user need or desire.
Thus, the present invention also relates to a method for dispensing sheets from a stack of sheets in overlying substantially parallel relationship, comprising: [0080]
(a) providing suitable airstreams over one end of the upper sheet of the stack such as to curl up said end and separate a portion of said sheet including said end from the stack; [0081]
(b) creating a suitable holding force, typically but not limited to a suction force, such as to hold said edge abutted against a suitable pickup device, and terminating the said airstreams; [0082]
(c) clamping the separated portion of the upper sheet in (b) and optionally terminating the holding force; [0083]
(d) displacing at least a part of the sheet by a peeling motion in a direction substantially towards a second end opposed to said end. [0084]
Thus, the apparatus ([0085] 100) typically operates cyclically, wherein in each cycle a single sheet (10) is dispensed from the stack as a result of two operations. In the first operation, as illustrated in FIGS. 7(a) to 7(d), the piston drive (40) is in the lower position, with the pickup head (22) gently resting on the upper sheet (10′) which is to be removed from the stack. Airstreams provided by the openings (62) initially curl the free end (A′), which may comprise, for example, a corner or edge of the sheet (10′), separating the end (A′) from the adjacent sheet (10), bringing the end (A′) towards the cylindrical member (60). Suction is then provided via apertures (66), causing the end (A′) to be firmly held against the cylindrical member (60), whereupon the airstreams are terminated. The piston drive (40) then moves upwards and sidewards to its upper position, thereby separating a greater portion (X) of the upper sheet (10′) in a peeling non-sliding motion.
Then, in the second operation, and as illustrated in FIGS. [0086] 7(e) to 7(h), the peeling mechanism (50) operates by displacing the clamping mechanism (70) from the dispensing position (DP) to the clamping position (CP) about axis (82), typically via a swinging motion. The jaws (72), in the open position, thus move past the portion (X) of the upper sheet (10′), whereupon the actuating mechanism (74) closes the jaws (72), thereby clamping the sheet (10′) close to the first edge (A). At this point the suction via apertures (66) is terminated, and the sheet (10) is held only via the jaws (72). The clamping mechanism (70) is then swung back about axis (82) from the clamping position (CP) to the dispensing position (DP), peeling the upper sheet (10′) from the stack, and holding the sheet (10′) in a substantially vertical position, illustrated as (10″), at which stage it may be optionally impregnated with liquid via spraying system (300). The hanging sheet (10″) may then be dropped into trough (90) for collection by the user. Alternatively, the hanging sheet (10″) may remain hanging until a user requires the sheet (10″), whereupon as a user's hand approaches the sheet (10′″) this is disengaged from the clamping mechanism (70), enabling the user to grasp and remove the sheet (10″). Thus, suitable detection means such as a photocell arrangement for example, may detect the entry of the user's hand into the apparatus (100) via opening (95), and the detection means then provide a suitable signal for a controller to release jaws (72).
Alternatively, in the second operation the clamps ([0087] 70) may be configured so that instead the free end (A) is moved in a clockwise direction (with respect to FIGS. 7(e) to 7(g), such as to minimize the sliding motion between the remaining part of the uppermost sheet and the sheet below it, and blowing means can then be provided to blow end (B) of the sheet towards the front of the device, oriented on the left part of FIG. 7(g).
Thus, the second operation needs to be properly synchronised with the first operation in order that the sheet ([0088] 10′) is in the correct position for clamping via the clamping mechanism (70) before the jaws (72) are activated. Similarly, the first operation has to be synchronised with the second operation so that the pickup device (20) does not descend onto a new upper sheet (10′) on the stack until the clamping mechanism (70) has been cleared from the clamping position (CP). Further, the spraying system (300) should not normally start spraying liquid until the end of the second operation, and prior to dropping the sheet (10″) into the trough (90).
Similarly, there is little need in starting the airstreams until the pickup head ([0089] 22) is resting gently on or is in close proximity to the stack, and should not be terminated until adequate suction has been applied to the sheet (10′) via apertures (66). Finally, suction should not normally be terminated at least until the clamping mechanism (70) is clamping the sheet (10′). However, while the vacuum should be terminated before the clamping mechanism (70) begins to move the sheet (10′) towards the dispensing position (DP), this may not always be required, and in fact the vacuum may be provided continuously, whereupon the clamping mechanism (70) merely pulls away the sheet (10′) from the cylindrical member (60) against the suction force provided by the vacuum. In many practical applications, no adverse effects are encountered when operating the apparatus (100) with continuous vacuum provided at the apertures (66).
Preferably, such synchronisations may be carried out under computer control using a suitable microprocessor operatively connected to each of the elements—the pickup device ([0090] 20) including the means for generating of the airstreams and creating the vacuum, and the cylinder-piston drive (40); the peeling mechanism (50), including the actuation mechanism (75) and driver; and the spraying system (300)—all of which are preferably electrically operated. Thus, the timing and duration of each element of the operations may be individually controlled, as required, providing flexibility of operation, according to need or desire.
Alternatively, and as illustrated with respect to the first embodiment of the apparatus ([0091] 100) in FIGS. 1 to 6, synchronisation of the two operations may be accomplished mechanically. Thus, referring to FIGS. 1 and 4 in particular, pickup device (20) comprises upwardly extending arms (25) each of which is pivotally attached to the pickup head (22) and to a corresponding one of two projections or tabs (76), each of which extends diametrically from the respective arm (75) of the clamping mechanism (70) with respect to the shaft (80). Further, the lower free end (42) of the piston drive (40) is pivotally mounted to the pickup head (22), and the upper end (44) is similarly pivotally mounted to the fixed point (110) of the housing (200). With this arrangement, and with suitable dimensions and profiles being chosen for the interacting mechanical linkage components, the first operation may be at least partially mechanically synchronised with the second operation. Thus, when the pickup head (22) is in the lowermost position gently over the upper sheet (10′), the clamping mechanism (70), in particular the jaws (72) and support (73) are in the dispensing position (DP). As the pickup head (22) is moved upwards, the arms (25) cause a clockwise rotation of the arms (75) via the tabs (76) (referring to FIGS. 1 and 4) due to the linkage via the pivots. This has the effect of causing the clamping mechanism (70) to swing towards the clamping position (DP), and also to provide a horizontal motion to the pickup head (22). A pair of struts (85) pivotally mounted to the housing (200) and the pickup head (22) in parallelogram arrangement facilitates these motions. The motion is reversible as the pickup head (22) is lowered towards the stack again for the start of the next cycle.
While the apparatus and method of the invention has been described herein as directed, initially, to the pick-up head being lowered onto the stack, and particularly the upper sheet thereof, it is essential only to bring the two together. Thus, according to the present invention, the apparatus can be configured, additionally or alternatively, to provide the required relative movement to the stack or upper sheet such as to bring the upper sheet into proximity or contact with the pick up head. Hence, the apparatus can be configured to raise and displace the stack such as to position the upper sheet below the pick up head, such as when the pick up head generates the air streams, the free end of the upper sheet curls up and may be held onto the pick up head, in a similar manner to that described herein where only the pick up head moves with respect to the stack, mutatis mutandis. Similarly, both the pick up head and the stack may be configured to move such as to provide the required relative motion between the pick up head and the stack. [0092]
A similar situation also applies to the second operation, wherein the peeling mechanism has been described as providing the necessary displacement to the sheet to peel it away from the stack. Alternatively the apparatus, and particularly the stack, can also be configured to provide the necessary motion to the stack, once the clamping means have clamped the first end of the sheet, such that the stack moves away from the clamping means automatically peeling off the upper sheet therefrom. It is also clear that according to the invention, the second operation can be performed by moving both the stack and the peeling mechanism as required to effect the peeling action, as described herein mutatis mutandis. In such cases, the peeling mechanism comprises suitable displacement means for the stack. [0093]
Referring to FIGS. [0094] 8 to 13, a second and preferred embodiment of the dispensing apparatus of the present invention, comprises a pick-up head (which also comprises the peelback or peeling mechanism), generally designated (500), comprised in a housing (not shown), and is similar to the first embodiment of the invention as described herein, mutatis mutandis, with the following differences.
In this embodiment, the suction means and the blowing means are operatively connected. Thus, the pick-up head ([0095] 500) comprises a casing (510) accommodating a fan (530), air blower, compressor or the like, with an air inlet (512) and an exhaust (520) operatively connected to the fan (530) via appropriate passages in the casing (510). Thus, the fan (530) sucks in air via the inlet (512 and blows the air via the exhaust (520). A cylindrical member (540) having apertures (541) is provided above and forward of the exhaust (520) and is in fluid communication with the air inlet (512) via side pipes (560) connected to the casing (510). The air inlet (512) is thus operatively connected to the suction apertures (541) to provide suction when the fan (530) is operated, and the fan exhaust (520), in the form of a flattened nozzle, provides the required airstreams. As shown particularly in FIGS. 8, 13(a), 13(c) and 13(d), a valve (550) is provided to the air inlet (512) to enable the supply of air to the fan (530) to be selectively switched from the vacuum apertures (541) to the atmosphere, and vice versa. Thus, when the valve (550) is open, the fan (530) sucks air therethrough from the general atmosphere, while when the valve (550) is closed, the fan can only suck in air via the suction apertures (541), providing suction thereat. Advantageously, the valve (550) comprises a hinged flap arrangement that seals against the inlet (512), such that rotational movements or other predetermined movements of the pickup head (500) causes the flap to open or close with respect to the inlet (512), as described herein.
Thus, the fan ([0096] 530) can operate continuously to provide the required airstreams, and the properly synchronised valve (550) enables suction to be provided to the apertures (541) when needed to hold the end of the sheet, as it curls over the cylindrical member (540). Similarly, suction may be terminated from the apertures (541) when required by means of the valve (550), for the subsequent peel back or release of the sheet.
In this embodiment, and referring particularly to FIG. 13([0097] a) to 13(d), the means for grasping the sheet is in the form of a pair, but may be one or a plurality of, laterally distanced stationary clamping members (570), which reversibly clamp against the cylindrical member (540) when they are brought into proximity, and unclamp when they are distanced one from the other. The clamping members (570) are typically attached to the casing (510) via lateral arms (572). Alternatively, the arms (572) may be attached to the housing. In any case, the configuration of the clamping members (570), the arms (572) and the connection of the arms (572) to the casing (510) or housing are such as to enable synchronization of the clamping movement with the motion of the pickup head (500), in particular to provide a clamping action against the pickup head (500) after the head has separated the end of the sheet and is holding the same.
The pickup head ([0098] 500) is pivoted about axis (590) for enabling swinging motion, and may additionally comprise means for raising or lowering the head from a stack of sheets (10). Alternatively, the head may be pivoted from any other suitable fulcrum that provides the required motion between the head and the sheets of the stack.
Thus, referring to FIGS. [0099] 13(a) and 13(b), the pickup head (500) is tilted as shown with the exhaust (520) in proximity to the uppermost sheet, and the inlet (512) higher than the exhaust (520), such that the valve (550) is closed. When the fan is in operation, it receives air via the suction holes (541) and provides airstreams via the exhaust (520). The airstreams separate the end (12) of the uppermost sheet of the stack in a similar to that described with respect to the first embodiment, mutatis mutandis. Preferably, the stack is oriented such that a corner of the sheets (10) is aligned with the cylinder member (540), rather than an edge. This provides better separation performance, and also requires a narrower cylindrical member than when the end being separated comprises an edge of the sheet. After separating the corner (12) of the uppermost sheet (10), this is held against the cylindrical member (540) via the suction force provided by the apertures (541), such that this end (12) is at least partially wrapped over the cylinder. The pickup head (500) is then rotated about a suitable fulcrum, typically axis (590) such as to vertically displace it from the stack, and such as to bring the cylindrical member (540) into abutting contact with the stationary clamping members (570). Thus, the free end (12) of the sheet (10) is now clamped between the cylindrical member (540) and the stationary clamping members (570), and the valve (550) can be synchronized to then stop the suction to the apertures (541), typically by tilting the casing (510) sufficiently such that the valve opens, as illustrated in FIG. 13(c). In this embodiment, the peeling mechanism may be incorporated in the pick up head, and include suitable means for swinging the pickup head (500) with respect to the stack, particularly for lifting the sheet from the stack by an upward and backward motion such as to minimize relative movement between the second end (11) of the uppermost sheet and the stack. At this point, the sheet (10) may be pulled out of the housing via a suitable window (599) provided in the casing, which is partially indicated at (598) in FIG. 13(c).
If it is desired to impregnate the sheet with a suitable solution, then, just before pulling the sheet, a spraying system, optionally similar to that described with respect to the first embodiment, mutatis mutandis, but typically comprised in the head ([0100] 500) between the fan (530) and the exhaust (520), may optionally be employed for spraying a suitable liquid onto the sheet by means of airstreams provided by the fan (530). First, and referring to the position of the sheet in FIG. 13(c), the fan (230) is used once more to blow air to the sheet via the exhaust (520), such as to detach the second end (11) of the sheet (10) from the stack, as illustrated in FIG. 13(d), and to blow the sheet towards a suitable location, such as for example a trough (595). This is done while the second end (12) of the sheet is still substantially on the stack, by properly synchronizing the motion of the head (500) with the action of the fan (530). Then, the spraying system in the casing (510) is switched on, and the liquid is conveyed to the sheet via the airstreams provided by the fan (530). Alternatively, the original action of blowing the sheet to trough (595) may be concurrent with spraying the sheet with liquid. In either case, the sheet remains clamped between the cylindrical member (540) and the stationary clamp members (570) until it is retrieved by a user via the window (599). The trough (595) is useful in enabling liquid from the spray and from the sheet top be collected in an orderly manner, rather than allow dripping therefrom within the housing.
Whether the sheets are collected wet or dry via window ([0101] 599), the clamping force exerted between the clamping members (570) and the cylindrical member (540), while sufficient to hold the sheet and to peel the same from the stack, is nevertheless easily overcome by the pulling action of a user via the window (599).
The clamping mechanism may be adapted for starting a new dispensing cycle automatically after a sheet is taken therefrom by a user. For example, the clamping members ([0102] 570) and cylindrical member (540) may have electrical contacts or the like, which when in direct contact with one another, provide a signal for the next dispensing cycle to begin. Such direct contact is only possible after the sheet is removed. Alternatively, a photosensor or any other suitable means may be used for detecting the absence of a sheet between the clamping members (570) and the cylindrical member (540). Additionally or alternatively, a new cycle may begin only when requested by a user.
In a variant of the second embodiment, the function of the clamping members ([0103] 570) may be performed by the holding means, i.e., by the suction provided between the sheet and the cylindrical member (540) via suction apertures (541). In such a case, the fan (530) needs to be operating continuously during the peeling action of the pick up head (which thus also constitutes the peeling mechanism), and the valve (550) needs to be closed during the same period. Thus, in some embodiments the clamping mechanism of the peeling mechanism may actually be constituted by the holding means of the pick up head.
While in the foregoing description describes in detail only a few specific embodiments of the invention, it will be understood by those skilled in the art that the invention is not limited thereto and that other variations in form and details may be possible without departing from the scope and spirit of the invention herein disclosed or exceeding the scope of the claims. [0104]

Claims

1. Apparatus for dispensing sheets comprising:

a) a support for accommodating a stack of sheets in overlying parallel relationship;

b) a pickup device overlying said support and comprising:

(i) blowing means for producing airstreams over one end of the upper sheet of a stack that may be accommodated by said support, such as to curl up said end and separate a portion of said upper sheet including said end from the stack; and

(ii) suitable holding means such as to hold at least part of said portion abutted against said pickup device such that said airstreams may be terminated;

c) a peeling mechanism having a clamping mechanism for clamping the separated portion of the upper sheet and adapted for displacing at least a portion of the sheet in a peeling motion with respect to a remainder of said stack that may be accommodated by said support.

2. Apparatus as claimed in claim 1, wherein said pickup head comprises a displacement arrangement for reciprocally moving said pickup device towards and away from the stack that may be accommodated by said support.

3. Apparatus as claimed in claim 2, wherein said displacement arrangement is adapted for providing vertical as well as horizontal motion to said pickup device.

4. Apparatus as claimed in claim 3, wherein said pickup head is configured to reciprocally rotate about a suitable axis such as to provide a desired vertical and horizontal movement to a part of said pickup head, wherein said part of said pickup head comprises said blowing means and said holding means.

5. Apparatus as claimed in claim 2, wherein said displacement arrangement comprises a piston driver that is electrically actuable and controllable by any suitable electric, electronic or computer means.

6. Apparatus as claimed in claim 1, wherein said holding means comprises a suitable suction means.

7. Apparatus as claimed in claim 6, wherein said suction means comprises a cylindrical member having suitable apertures operatively connected to a suitable suction source.

8. Apparatus as claimed in claim 7, wherein said cylindrical member is substantially aligned with said end of said upper sheet.

9. Apparatus as claimed in claim 8, wherein said blowing means comprise suitable openings provided in a plenum chamber accommodated in said pick up head, said openings being operatively connected to a suitable compressed air source such as to provide substantially tangential airstreams with respect to said cylindrical member.

10. Apparatus as claimed in claim 9, wherein said compressed air source comprises an air compressor arrangement, including a fan or air blower.

11. Apparatus as claimed in claim 10, wherein said suction means and said blowing means are operatively interconnected.

12. Apparatus as claimed in claim 10, wherein said air compressor arrangement is electrically actuable and controllable by any suitable control means including electric, electronic or computer means.

13. Apparatus as claimed in claim 7, wherein said vacuum source comprises a suitable vacuum pump, ejector or suction pump arrangement.

14. Apparatus as claimed in claim 13, wherein said pump arrangement is electrically actuable and controllable by any suitable control means including electric, electronic or computer means.

15. Apparatus as claimed in claim 1, wherein said clamping mechanism comprises a support member having clamping means at each end thereof adapted for clamping said separated portion of said upper sheet, and a pair of arms substantially orthogonal to said support member pivotally mounted with respect to a suitable swinging axis.

16. Apparatus as claimed in claim 15, wherein said clamping means comprise suitable jaws.

17. Apparatus as claimed in claim 16, wherein said clamping means comprise a substantially stationary clamping member adapted for clamping with respect to said cylinder after said pickup head separates and holds an end of an upper sheet.

18. Apparatus as claimed in claim 16, wherein said jaws are electrically actuable and controllable by any suitable control means including electric, electronic or computer means.

19. Apparatus as claimed in claim 15, wherein said clamping mechanism is displaceable by means of a suitable driving mechanism.

20. Apparatus as claimed in claim 19, wherein said driving mechanism is electrically actuable and controllable by any suitable control means including electric, electronic or computer means.

21. Apparatus as claimed in claim 15, wherein said peeling mechanism is suitably synchronised with said pickup device.

22. Apparatus as claimed in claim 21, wherein said synchronisation is provided by suitable mechanical means.

23. Apparatus as claimed in claim 21, wherein said synchronisation is provided by suitable synchronisation means including electrical, electronic or computer means.

24. Apparatus as claimed in claim 1, wherein said support comprises a tray.

25. Apparatus as claimed in claim 24, wherein said tray is in horizontal alignment.

26. Apparatus as claimed in claim 25, wherein said tray is horizontally reversibly movable from a position outside the apparatus to a position inside the apparatus.

27. Apparatus as claimed in claim 1, further comprising a suitable spraying system for spraying at least one suitable liquid to a said sheet, said spraying system being operatively connected to at least one source of said liquids and comprising at least one nozzle adapted for spraying said at least one liquid.

28. Apparatus as claimed in claim 27, wherein said spraying system is adapted for spraying a said sheet after the sheet has been substantially fully separated from the said stack.

29. Apparatus as claimed in claim 27, wherein said spraying system is suitably synchronised with at least with said peeling system.

30. Apparatus as claimed in claim 29, wherein said synchronisation is provided by suitable mechanical means.

31. Apparatus as claimed in claim 30, wherein said mechanical means comprises suitable mechanical linkage between said pickup device and said peeling mechanism.

32. Apparatus as claimed in claim 29, wherein said synchronisation is provided by suitable synchronisation means including electrical, electronic or computer means.

33. Apparatus as claimed in claim 27, wherein said spraying system further comprising suitable means for enabling any desired combination of said liquids to be sprayed in any desired relative proportions onto said sheet.

34. Apparatus as claimed in claim 27, wherein said spraying system is operatively connected to said blowing means, wherein said blowing means generate suitable airstreams to carry said liquid to said sheet.

35. Apparatus as claimed in claim 34, wherein said spraying system is suitably synchronized with said blowing means such as to enable a sheet to be sprayed after the sheet has been fully separated from the said stack.

36. Apparatus as claimed in claim 1, wherein said holding means constitute said clamping mechanism.

37. Apparatus as claimed in claim 1, wherein said peeling mechanism is incorporated in said pick up head.

38. Apparatus as claimed in claim 37, wherein said peeling mechanism includes suitable means for swinging the pickup head with respect to the stack.

39. Method for dispensing sheets from a stack of sheets in overlying substantially parallel relationship, comprising:

(a) providing suitable airstreams over a first end of an upper sheet of the stack such as to curl up said first end and separate a portion of said upper sheet including said first end from the stack;

(c) clamping the separated portion of the upper sheet in (b) and terminating the holding force;

(d) displacing at least a part of the sheet in a peeling motion with respect to a remainder of said stack.

40. Method as claimed in claim 39, wherein in step (d) said at least a part of the sheet is displaced in a direction substantially towards a second end of said upper sheet opposed to said first end of the sheet.

41. Method as claimed in claim 39, wherein said holding force comprises a suction force.

42. Method as claimed in claim 39, wherein in step (d) all of said sheet is displaced in a peeling motion from said stack.

43. Method as claimed in claim 40, wherein a remaining part of said sheet which is still in overlying relationship with said stack is removed from the stack by providing a force to the sheet in a direction substantially towards said first end.

44. Method as claimed in claim 43, wherein said force is provided by generating suitable airstreams to impinge on said sheet.

45. Method as claimed in claim 39, wherein said first end comprises an edge of said sheet.

46. Method as claimed in claim 39, wherein said first end comprises a corner of said sheet.

47. Method as claimed in claim 39, further comprising the step (e) of impregnating the separated sheet with at least one suitable liquid after the sheet has been separated.

48. Method as claimed in claim 39, further comprising the step (f) of releasing the separated sheet for collection or further processing.

49. Method as claimed in claim 39, wherein step (a) is effected by bringing together a suitable pickup and said upper sheet, said blowing means comprising a cylindrical member having suitable openings for providing said airstreams.

50. Method as claimed in claim 49, wherein said pickup device is lowered onto device until it rests gently on said upper sheet.

51. Method as claimed in claim 49, wherein said upper sheet is raised until it is in gentle contact with said pick up device.

52. Method as claimed in claim 40, wherein said suction force in step (b) is provided via suitable apertures in said pickup device operatively connected to a suitable vacuum source.

53. Method as claimed in claim 39, wherein step (c) is effected by means of a suitable peeling mechanism including a clamping mechanism having a pair of opposed clamping means adapted for clamping said separated portion of said upper sheet, and a pair of arms extending orthogonally from said jaws and pivotally mounted with respect to a suitable swinging axis.

54. Method as claimed in claim 53, wherein said clamping means are in the form of jaws.

55. Method as claimed in claim 47, wherein step (e) is effected by means of a spraying system adapted for spraying said liquid to the separated sheet.

56. Method as claimed in claim 39, wherein steps (a) to (d) are synchronised with respect to one another.

57. Method as claimed in claim 47, wherein at least steps (d) to (e) are suitably synchronised with respect to one another.

58. Method as claimed in claim 55, wherein steps (a) to (d) are at least partially synchronised by any suitable mechanical means.

59. Method as claimed in claim 58, wherein said mechanical means includes suitable mechanical linkage between said pickup device and said peeling mechanism.

60. Method as claimed in claim 55, wherein said synchronisation is provided by suitable synchronization means including electrical, electronic or computer means.

61. Method as claimed in claim 57, wherein said synchronisation is provided by suitable synchronization means including electrical, electronic or computer means.