U.S. patent application number 10/481308 was filed with the patent office on 2004-11-04 for apparatus and method for dispensing sheets.
Invention is credited to Granot, Daniel, Sinai, Dan.
Application Number | 20040217540 10/481308 |
Document ID | / |
Family ID | 11075532 |
Filed Date | 2004-11-04 |
United States Patent
Application |
20040217540 |
Kind Code |
A1 |
Sinai, Dan ; et al. |
November 4, 2004 |
Apparatus and method for dispensing sheets
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.
Inventors: |
Sinai, Dan; (Haifa, IL)
; Granot, Daniel; (Nesher, IL) |
Correspondence
Address: |
Kevin D McCarthy
Roach Brown McCarthy & Gruber
1620 Liberty Building
Buffalo
NY
14202
US
|
Family ID: |
11075532 |
Appl. No.: |
10/481308 |
Filed: |
May 27, 2004 |
PCT Filed: |
June 19, 2002 |
PCT NO: |
PCT/IL02/00486 |
Current U.S.
Class: |
271/98 |
Current CPC
Class: |
B65H 3/14 20130101; B65H
2301/423245 20130101; B65H 2301/42324 20130101; B65H 2406/121
20130101; B65H 2406/341 20130101; B65H 2301/4233 20130101; B65H
2406/122 20130101 |
Class at
Publication: |
271/098 |
International
Class: |
B65H 003/14 |
Foreign Application Data
Date |
Code |
Application Number |
Jun 20, 2001 |
IL |
143894 |
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; (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 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.
Description
FIELD OF THE INVENTION
[0001] 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
[0002] 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.
[0003] 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.
[0004] 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.
[0005] 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.
[0006] 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.
[0007] 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.
[0008] 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.
[0009] 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.
[0010] 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.
[0011] 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.
[0012] 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.
[0013] 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
[0014] 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.
[0015] Other purposes and advantages of the invention will appear
as the description proceeds.
SUMMARY OF THE INVENTION
[0016] The present invention relates to an apparatus for dispensing
sheets comprising:
[0017] (a) a support for accommodating a stack of sheets in
overlying parallel relationship;
[0018] (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;
[0019] (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.
[0020] 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.
[0021] 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.
[0022] 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.
[0023] The air compressor arrangement is preferably electrically
actuable and controllable by any suitable control means including
electric, electronic or computer means.
[0024] 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.
[0025] 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.
[0026] 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.
[0027] 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.
[0028] 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.
[0029] 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.
[0030] 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.
[0031] 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.
[0032] 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.
[0033] The present invention also relates to corresponding methods
for dispensing sheets from a stack of sheets in overlying
substantially parallel relationship, comprising:
[0034] (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;
[0035] (b) creating a suitable holding force such as to hold said
first end abutted against a suitable pickup device, and terminating
the said airstreams;
[0036] (c) clamping the separated portion of the upper sheet in (b)
and terminating the suction force;
[0037] (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.
[0038] 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.
[0039] 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.
[0040] The said first end comprises an edge or a corner of said
sheet.
[0041] 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.
[0042] 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.
[0043] 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
[0044] FIG. 1 illustrates, in cross-sectional side view, the main
elements of a first embodiment of the present invention in the
dispensing position.
[0045] FIG. 2 illustrates, in front perspective view, the
embodiment of FIG. 1.
[0046] FIG. 3 illustrates, in rear perspective view, the embodiment
of FIG. 1.
[0047] FIG. 4 illustrates, in cross-sectional side view, the main
elements of a first embodiment of the present invention in the
clamping position.
[0048] FIG. 5 illustrates, in front perspective view, the
embodiment of FIG. 4.
[0049] FIG. 6 illustrates, in rear perspective view, the embodiment
of FIG. 4.
[0050] FIGS. 7(a) to 7(h) illustrate schematically the operation of
the first embodiment of the present invention.
[0051] FIG. 8 illustrates, in cross-sectional side view, the main
elements of a second embodiment of the present invention.
[0052] FIG. 9 illustrates, in bottom perspective view, the
embodiment of FIG. 8.
[0053] FIG. 10 illustrates, in cross-sectional upper view, the
embodiment of FIG. 8 taken along A-A.
[0054] FIG. 11 illustrates, in top view, the embodiment of FIG.
8.
[0055] FIG. 12 illustrates, in cross-sectional side view, the
embodiment of FIG. 11 taken along B-B.
[0056] FIGS. 13(a) to 13(d) illustrate schematically the operation
of the second embodiment of the present invention.
DESCRIPTION
[0057] 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.
[0058] 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.
[0059] The present invention thus relates to an apparatus for
dispensing sheets comprising:
[0060] a support for accommodating a stack of sheets in overlying
parallel relationship;
[0061] 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
[0062] 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.
[0063] Thus, referring to the figures, in particular FIGS. 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.
[0064] The tray (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
[0065] The pickup device (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.
[0066] In the first embodiment, the displacement arrangement is in
the form of a piston drive (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.
[0067] 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 (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.
[0068] 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 (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.
[0069] 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 (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).
[0070] Referring in particular to FIGS. 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.
[0071] The piston drive (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.
[0072] Alternatively, the piston drive (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).
[0073] In the first embodiment, the peeling mechanism (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).
[0074] Referring particularly to FIGS. 4 and 7(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).
[0075] As the support bar (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.
[0076] In other embodiments, the peeling mechanism (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.
[0077] The peeling mechanism (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.
[0078] While the sheet (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).
[0079] The spraying system (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.
[0080] Thus, the present invention also relates to a method for
dispensing sheets from a stack of sheets in overlying substantially
parallel relationship, comprising:
[0081] (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;
[0082] (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;
[0083] (c) clamping the separated portion of the upper sheet in (b)
and optionally terminating the holding force;
[0084] (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.
[0085] Thus, the apparatus (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.
[0086] Then, in the second operation, and as illustrated in FIGS.
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).
[0087] Alternatively, in the second operation the clamps (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).
[0088] Thus, the second operation needs to be properly synchronised
with the first operation in order that the sheet (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).
[0089] Similarly, there is little need in starting the airstreams
until the pickup head (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).
[0090] Preferably, such synchronisations may be carried out under
computer control using a suitable microprocessor operatively
connected to each of the elements--the pickup device (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.
[0091] Alternatively, and as illustrated with respect to the first
embodiment of the apparatus (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.
[0092] 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.
[0093] 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.
[0094] Referring to FIGS. 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.
[0095] In this embodiment, the suction means and the blowing means
are operatively connected. Thus, the pick-up head (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.
[0096] Thus, the fan (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.
[0097] In this embodiment, and referring particularly to FIG. 13(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.
[0098] The pickup head (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.
[0099] Thus, referring to FIGS. 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).
[0100] 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
(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.
[0101] Whether the sheets are collected wet or dry via window
(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).
[0102] 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 (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.
[0103] In a variant of the second embodiment, the function of the
clamping members (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.
[0104] 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.
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