U.S. patent application number 10/611220 was filed with the patent office on 2004-06-17 for heat seal apparatus for lens packages.
Invention is credited to Duncan, Gregory S., Hall, Gary S., Sanka, Ravi S., Schlagel, Mark E., Voss, Leslie A., Widman, Michael F..
Application Number | 20040112008 10/611220 |
Document ID | / |
Family ID | 32512671 |
Filed Date | 2004-06-17 |
United States Patent
Application |
20040112008 |
Kind Code |
A1 |
Voss, Leslie A. ; et
al. |
June 17, 2004 |
Heat seal apparatus for lens packages
Abstract
The present invention relates to an apparatus for packaging
contact lenses. The apparatus includes a compliant head, improved
heater and improved heat seal die.
Inventors: |
Voss, Leslie A.;
(Jacksonville, FL) ; Duncan, Gregory S.;
(Gainesville, FL) ; Sanka, Ravi S.; (Jacksonville,
FL) ; Hall, Gary S.; (Jacksonville, FL) ;
Schlagel, Mark E.; (Jacksonville, FL) ; Widman,
Michael F.; (Jacksonville, FL) |
Correspondence
Address: |
PHILIP S. JOHNSON
JOHNSON & JOHNSON
ONE JOHNSON & JOHNSON PLAZA
NEW BRUNSWICK
NJ
08933-7003
US
|
Family ID: |
32512671 |
Appl. No.: |
10/611220 |
Filed: |
July 1, 2003 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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10611220 |
Jul 1, 2003 |
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09217878 |
Dec 21, 1998 |
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10611220 |
Jul 1, 2003 |
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09818725 |
Mar 27, 2001 |
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6695988 |
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10611220 |
Jul 1, 2003 |
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10417936 |
Apr 17, 2003 |
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60393187 |
Jul 2, 2002 |
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60394398 |
Jul 8, 2002 |
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Current U.S.
Class: |
53/329.3 |
Current CPC
Class: |
B29C 65/18 20130101;
B29C 66/71 20130101; B29C 66/81465 20130101; B65B 25/008 20130101;
B65B 41/18 20130101; B29C 66/9221 20130101; B29C 66/919 20130101;
B29C 66/71 20130101; B29C 66/8432 20130101; B29C 66/849 20130101;
B29C 66/8322 20130101; B65B 7/164 20130101; B29C 66/71 20130101;
B29D 11/00067 20130101; B29C 66/91421 20130101; B29C 66/8242
20130101; B29C 66/72321 20130101; B29C 66/131 20130101; B29C
66/91431 20130101; B29C 66/71 20130101; B29C 66/92431 20130101;
B29C 66/73921 20130101; B29C 66/961 20130101; B29C 66/114 20130101;
B29C 65/7841 20130101; B29C 66/53461 20130101; B29C 66/8161
20130101; B65B 5/04 20130101; B29C 66/92451 20130101; B29K 2023/06
20130101; B29D 11/0024 20130101; B29L 2011/0041 20130101; B29K
2705/02 20130101; B29C 66/24221 20130101; B29C 66/112 20130101;
B29K 2023/12 20130101; B29K 2025/06 20130101 |
Class at
Publication: |
053/329.3 |
International
Class: |
B65B 051/14 |
Claims
What is claimed is:
1. An apparatus for packaging contact lenses in a plurality of
contact lens containers, each container having a recess, a sealing
flange about said recess, and a contact lens within said recess, a
plurality of said containers being sealed in said apparatus to a
contiguous lidstock to form a set of packages, said apparatus
comprising: a plurality of lifts; a plurality of platens located in
a lower portion of the apparatus, each of said platens comprising a
compliant head that is compliant in more than one direction, each
of said platens adjacent to one another, each of said platens being
individually supported by one of said lifts; a plurality of
discrete carriers, said carriers being movable within said
apparatus onto said plurality of said platens, such that each of
said carriers is mounted on a respective one of said platens, a
single one of said containers being mounted on a single one of said
carriers to provide a plurality of said containers located adjacent
to one another; a lidstock maneuvering system for placing a
contiguous lidstock over said plurality of said containers located
adjacent to one another; and a mandrel disposed above said
plurality of platens; wherein pressure is applied to said
contiguous lidstock and said flanges of said containers by said
mandrel and said plurality of platens to adhere said contiguous
lidstock to said plurality of said containers to form a set of
packages.
2. The apparatus according to claim 1, wherein each carrier has a
cavity, each said recess of said container being received in said
cavity of said carrier.
3. The apparatus according to claim 1, wherein said lidstock has a
thickness and said container has a thickness, and further wherein
said mandrel is selectively moveable between a retracted upper
position and an engaged lower position to seal said lidstock to
said containers, and wherein in said lower position, a pressure
applied by said mandrel against each of said platens is maintained
within a predetermined range by the respective lifts, thereby
compensating for tolerance differences in the thickness of said
containers and the thickness of said lidstock to ensure that an
adequate seal is formed between said lidstock and each of said
containers.
4. The apparatus according to claim 3, further comprising a
pressure transducer being connected to said lifts, and further
wherein said lifts apply pressure to said containers within a
predetermined range, as determined by said pressure transducer.
5. The apparatus according to claim 1 wherein said mandrel is
heated.
6. The apparatus of claim 1, wherein said lidstock comprises print,
and further wherein said lidstock maneuvering system further
comprises: a vision alignment inspection system having means for
checking the print quality on said lidstock and for simultaneously
checking for registration of said lidstock within said apparatus
based on the location of said print.
7. The apparatus of claim 6, wherein said lidstock maneuvering
system further comprises a printing system and a cutting system,
wherein said lidstock is fed from a roll under tension into said
printing system and said cutting system, and said vision alignment
inspection system is located after said printing system.
8. The apparatus of claim 6, wherein said lidstock maneuvering
system further comprises a printing system and a cutting system,
wherein said lidstock is fed from a roll under tension into said
printing system and said cutting system and said alignment
inspection system is located between said printing system and said
cutting system.
9. The apparatus of claim 6, further comprising a heat seal
apparatus, wherein said lidstock is mechanically controlled after
said vision alignment inspection system to prevent misregistration
of said lidstock in said heat seal apparatus.
10. The apparatus of claim 3, wherein said lidstock is held in
position by said lidstock maneuvering system over said containers
until said mandrel contacts said lidstock in said engaged lower
position.
11. The apparatus of claim 1, wherein said apparatus further
comprises: said mandrel further comprising a plurality of dies each
having a die cylinder; said dies disposed above each of said
carriers; wherein said cylinders apply pressure, within a
predetermined range, to each of said dies.
12. An apparatus for packaging contact lenses in a plurality of
contact lens containers, each container having a recess, a sealing
flange about said recess, and a contact lens within said recess, a
plurality of said containers being sealed in said apparatus to a
contiguous lidstock to form a set of packages, said apparatus
comprising: a platen in a lower portion of the apparatus, said
platen comprising a compliant head that is compliant in more than
one direction, said platen capable of supporting a plurality of
carriers; a plurality of discrete carriers, said carriers being
movable within said apparatus onto said platen so that said
carriers are located adjacent to one another; a lidstock
maneuvering system for placing lidstock over a plurality of said
containers; and a plurality of lifts; a plurality of mandrels
disposed above said platen; each of said mandrels being
individually supported by one of said lifts and such that each of
said carriers is located below each of said mandrels; whereby
pressure is applied to said lidstock and said flange of each said
container by said mandrels and said platen to adhere said lidstock
to said containers.
13. The apparatus according to claim 12, wherein said lidstock has
a thickness and said container has a thickness, and further wherein
said mandrels are selectively moveable between a retracted upper
position and an engaged lower position to seal said lidstock to
said containers, and wherein in said lower position, a pressure
applied by said mandrels against said platen is maintained within a
predetermined range by the respective lifts, thereby compensating
for tolerance differences in the thickness of said containers and
the thickness of said lidstock to ensure that an adequate seal is
formed between said lidstock and each of said containers.
14. The apparatus according to claim 12, further comprising a
pressure transducer being connected to said lifts, and further
wherein said lifts apply pressure to said containers within a
predetermined range, as determined by said pressure transducer.
15. The apparatus according to claim 12 wherein said mandrel is
heated.
16. The apparatus of claim 12, wherein said lidstock maneuvering
system further comprises: a vision alignment inspection system
having means for checking the print quality on said lidstock and
for simultaneously checking for registration of said lidstock
within said apparatus based on the location of said print.
17. The apparatus of claim 16, wherein said lidstock maneuvering
system further comprises a printing system and a cutting system,
wherein said lidstock is fed from a roll under tension into said
printing system and said cutting system, and said vision alignment
inspection system is located after said printing system.
18. The apparatus of claim 16, wherein said lidstock maneuvering
system further comprises a printing system and a cutting system,
wherein said lidstock is fed from a roll under tension into said
printing system and said cutting system and said alignment
inspection system is located between said printing system and said
cutting system.
19. The apparatus of claim 16, further comprising a heat seal
apparatus, wherein said lidstock is mechanically controlled after
said vision alignment inspection system to prevent misregistration
of said lidstock in said heat seal apparatus.
20. The apparatus of claim 17, wherein said cutting system is
located after said printing system.
21. The apparatus of claim 13, wherein said lidstock is held in
position by said lidstock maneuvering system between said mandrels
and said platen until said mandrel contacts said lidstock.
22. The apparatus according to claim 1, wherein said compliant head
is compliant in the vertical and horizontal directions.
23. The apparatus according to claim 1, wherein said compliant head
is compliant in the pitch and yaw directions.
24. The apparatus according to claim 1, wherein each of said
platens comprises a heat seal die, said heat seal die comprises a
wafer heater capable of increasing the temperature of the heat seal
die with a lag time of less than 1 second.
25. The apparatus according to claim 12, wherein said compliant
head is compliant in the vertical and horizontal directions.
26. The apparatus according to claim 12, wherein said compliant
head is compliant in the pitch and yaw directions.
27. The apparatus according to claim 12, wherein each of said
platens comprises a heat seal die, said heat seal die comprises a
wafer heater capable of increasing the temperature of the heat seal
die with a lag time of less than 1 second.
28. An apparatus for packaging contact lenses in a plurality of
contact lens containers, each container having a recess, a sealing
flange about said recess, and a contact lens within said recess, a
plurality of said containers being sealed in said apparatus to a
contiguous lidstock to form a set of packages, said apparatus
comprising: a heat seal die comprising extra thermal mass in the
area of the heat seal die that contacts the lidstock where there is
a greater amount of foil in contact with said sealing flange.
Description
CROSS REFERENCE TO RELATED APPLICATIONS
[0001] This application claims the benefit of U.S. Provisional
Application Serial No. 60/393,187 filed on Jul. 2, 2002 and U.S.
Provisional Application Serial No. 60/394,398 filed on Jul. 8,
2002.
[0002] This application is a continuation in part of "Heat Seal
Apparatus For Lens Packages," U.S. Ser. No. 09/217,878 (VTN-415), a
continuation in part of "Method and Apparatus for Washing or
Hydration of Ophthalmic Devices," U.S. Ser. No.
09/818,725(VTN-533), and a continuation in part of "Contact Lens
Transfer and Transfer Device Cleaner," U.S. Ser. No. 10/417,936
(VTN-597), all of which are incorporated herein by reference.
FIELD OF THE INVENTION
[0003] The present invention relates to an apparatus for heat
sealing containers containing an ophthalmic contact lens to form a
sealed package. More specifically, the present invention relates to
an apparatus for heat sealing a lidstock to a lens container to
form a package by controlling the application of heat and pressure
for each lid and container assembly.
BACKGROUND OF THE INVENTION
[0004] In the manufacture of hydrophilic ("soft") ophthalmic
contact lenses, it is conventional to package each manufactured
lens in a disposable package for containing a single lens and
predetermined amount of liquid (generally buffered saline).
Typically, the lens and liquid are introduced to a cavity or well
in a container. The container is usually formed from a
thermoplastic (e.g., molded polypropylene or polystyrene). After
the lens and liquid are placed into the container, the container is
sealed by applying a foil strip to the top of the container to form
a lid and heat sealing the strip to the top of the container to
form a package. The heat sealed package containing both the lens
and liquid is then subjected to further processing, including for
example, sterilization.
[0005] Conventional apparatus used for the high speed packaging of
contact lenses on an assembly line is designed to permit inspection
and packaging of several contact lenses simultaneously. Typically,
a plurality (generally 6, 8 or 10) of containers are mounted in a
fixed carrier rack having a cavity for receiving each container. A
contact lens and liquid are introduced to each container mounted on
the rack. The rack of containers is then conveyed to an inspection
station where each container is inspected to ensure that a contact
lens is present and not defective. The rack then moves onto a
platen in a heat sealing station where a preformed sheet of foil
stock is positioned over the rack of containers. A heated mandrel
is then applied to the rack to apply predetermined heat and
pressure for a predetermined time, thereby heat sealing the foil
stock to each container and forming sealed packages. As a result,
each of the containers is now each heat sealed to the sheet of foil
stock and is accordingly joined together to form multi-package
arrays. The foil stock is provided with perforations to permit the
packages to be separated from each other after further downstream
processing and/or shipping.
[0006] The packaging approach described above presents several
disadvantages. For example, by providing a plurality of lens
containers on each rack, the detection and identification of a
defective or missing lens on the rack at the inspection station is
complicated. A complex matrix tracking system must be employed to
identify which container or containers on the rack has failed
inspection and track them through the process until they can be
removed.
[0007] Another problem inherent in processing multiple containers
simultaneously in a fixed rack arrangement is that each container
on the rack is subjected to identical heat sealing conditions. Due
to variations in the molding process, the molded thermoplastic
containers sometimes vary in height. In such an event, a container
of non-standard height may be subjected to either too little
pressure (if too short) or too much pressure (if too tall) compared
to the pressure experienced by a container of standard height. As a
result, the heat seal formed on one or more of the array of
packages joined together by the perforated foil sheet may be of
unacceptable quality. One defective heat seal in the array will
require that the entire array of packages be discarded, and, thus,
an entire production lot may be subject to further testing for heat
seal failures, which, if present, may require rejecting the entire
production lot.
[0008] Finally, in the prior art heat sealing apparatus, the sheet
of perforated foil stock is positioned over the rack of containers
upstream of the heated mandrel station. This arrangement relies on
gravity and friction to maintain the lidstock in position until the
heat seal is formed. Slight lateral movement of the foil stock
causes mis-registration of the stock on the set of containers and
could result in a defective set of packages.
[0009] The apparatus described above is disclosed in U.S. Pat. No.
5,687,541 issued to Martin et al. Other packages and packaging
apparatus systems are disclosed in U.S. Pat. No. 5,649,410 issued
to Martin et al., U.S. Pat. No. 5,561,970 issued to Edie et al.,
U.S. Pat. No. 5,094,609 issued to Kindt-Larsen, U.S. Pat. No.
4,691,820 issued to Martinez, U.S. Pat. No. 5,620,087 issued to
Martin et al., U.S. Pat. No. 5,749,205 issued to Edwards et al. and
U.S. Pat. No. 5,577,367 issued to Abrams et al. Each of the
references cited herein are incorporated by reference. In the event
of conflict in the meaning or interpretation of the present
specification and/or appended claims, the present specification
controls.
[0010] It will be apparent that there continues to be a need for an
apparatus capable of detecting and selectively removing failed
containers. In addition, the need exists for a heat sealing
apparatus capable of applying a predetermined amount of pressure to
each container in a group of containers being sealed
simultaneously. Finally, there is a need for a heat sealing
apparatus that is capable of maintaining a sheet of lidstock in
registration with the set of containers during heat sealing. There
is also a need for a sealing apparatus that is sensitive to angular
irregularities in container heights, and discrepancies in the
planes of the platen and the surfaces of the heat seal dies, and
one that can provide for more consistent heating of the heat seal
dies. The present invention addresses these needs.
SUMMARY OF THE INVENTION
[0011] The present invention relates to an apparatus for packaging
contact lenses. The apparatus includes a plurality of discrete lens
carriers and a plurality of contact lens containers. The carriers
are movable within the apparatus. A single one of the containers is
mounted on a single one of the carriers.
[0012] The present invention also relates to an apparatus for
automatically packaging contact lenses that includes a plurality of
lens carriers, a plurality of lifts, a plurality of contact lens
containers and either a plurality of platens and/or a plurality of
mandrels. One of the containers is mounted on a respective one of
the carriers. Each of the platens and/or each of the mandrels is
individually supported by one of the lifts. The lifts apply
pressure, within a predetermined range, to each of the
containers.
[0013] The present invention also relates to an apparatus for
automatically packaging contact lenses that includes a plurality of
contact lens containers. A heated mandrel is disposed above the
plurality of containers. The heated mandrel is preferably moveable
between a retracted position above the plurality of containers and
an engaged position immediately adjacent to the plurality of
containers. A lidstock is selectively movable between a retracted
position and an inserted position. The inserted position is between
the heated mandrel and the plurality of containers, whereby in the
inserted position the lidstock is fixedly held in position at least
until the heated mandrel contacts the lidstock while moving to the
engaged position.
[0014] The present invention also relates to an apparatus for
packaging contact lenses that includes a lidstock having indicia
printed thereon. The lidstock is fed from a roll under tension. A
vision alignment inspection system checks the print quality on the
lidstock and simultaneously checks for registration of the lidstock
within the apparatus.
[0015] In another aspect, the present invention relates to an
apparatus for packaging ophthalmic hydrophilic contact lenses
transported along a conveyor, each lens contained within a
container supported by a carrier. The apparatus includes a conveyor
for conveying carriers each supporting a container, each container
including a well for containing a contact lens and preferably a
heat sealing surface. The apparatus also includes a plurality of
platens, each of the platens attached to a lift capable of
independently exerting a preset pressure against the mandrel (and
the container between the platen and mandrel). Each platen receives
a single carrier. Preferably there is one transducer, which
generates an electrical signal corresponding to the pressure that
operates on the cylinders to assure that it is within prescribed
limits. A heated mandrel is disposed above the platens. The mandrel
is movable from a disengaged position to an engaged position. A
lidstock inserter capable of inserting a lidstock between the
mandrel in the disengaged position and the heat sealing surfaces of
the containers positioned above the plurality of platens is
provided. The inserter preferably holds the lidstock in place until
the mandrel contacts the lidstock against the container. In
addition, a signal processor is provided, capable of receiving the
pressure signal from the transducer, comparing the signal to a set
of predetermined values, and marking the array for rejection if the
pressure exerted by the lift is outside the predetermined
range.
BRIEF DESCRIPTION OF THE DRAWINGS
[0016] The above and still further objects, features and advantages
of the present invention will become apparent upon consideration of
the following detailed description of a specific embodiment
thereof, especially when taken in conjunction with the accompanying
drawings wherein like reference numerals in the various figures are
utilized to designate like components, and wherein:
[0017] FIG. 1 is a side elevation view of the heat sealing
apparatus according to the present invention;
[0018] FIG. 2 is a front elevation view of the heat sealing
apparatus illustrated in FIG. 1;
[0019] FIG. 3 is a perspective view of a contact lens
container;
[0020] FIG. 4 is a perspective view of a contact lens carrier with
a contact lens container received thereon;
[0021] FIG. 5 is a side view of another embodiment of the present
invention;
[0022] FIG. 6 is a schematic diagram of the pneumatic system of the
preferred heat sealing apparatus; and
[0023] FIG. 7 is a side view of the movement of the lidstock prior
to the heat seal apparatus.
[0024] FIG. 8 is a front view of another embodiment of the
invention.
[0025] FIG. 9 is a cross-sectional view of the embodiment shown in
FIG. 8 taken along the line c-c shown in FIG. 8.
[0026] FIG. 10 is a partial side perspective view of a compliant
head useful in the embodiment of this invention shown in FIGS. 8
and 9.
[0027] FIG. 11 is a side view of the compliant head shown in FIG.
10.
[0028] FIG. 12 is a side view of a portion of the compliant
head.
[0029] FIG. 13 is a partial cross-sectional view of a portion of
the compliant head.
[0030] FIG. 14 is a side perspective view of a heat seal die block
useful in this invention.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0031] Referring now to FIGS. 1 and 2, side and front elevation
views of a heat seal apparatus 10 for sealing a lidstock onto a
container to form a sealed contact lens package are illustrated.
The apparatus includes an upstream conveyor 12 capable of conveying
a plurality of individual lens carriers 14 (FIG. 4), in the
direction indicated by arrow A in FIG. 2, into the heat seal
apparatus 10.
[0032] As illustrated in FIG. 2, in the heat seal apparatus 10,
each individual carrier 14 is positioned above a discrete support
platen 16. Each platen 16 is supported by a lift, e.g., a hydraulic
or pneumatic (i.e., fluid) cylinder 18 which is operative to
vertically displace the respective platen and by a bearing block
20.
[0033] Each individual lens carrier 14 supports, on its upper
surface 22, a lens container 24, which contains a contact lens in a
cup-shaped recess or well 25. The containers can be a portion of
the mold, e.g., the front cure mold and/or the bottom half of a
contact lens package, which is conventionally referred to as the
bowl. Preferably, the container is a bowl. Referring now to FIG. 3,
container 24 includes a sealing flange 39, which is disposed about
cup-shaped recess 25. The individual lens carriers 14 are
incrementally moved into position in the heat sealing assembly such
that one lens carrier 14 is placed upon each of the platens 16. As
illustrated in FIG. 2, the heat seal assembly includes, in one
illustrative embodiment, five platens which each receive a single
lens carrier holding a container. However, in the currently
preferred exemplary embodiment, the heat seal assembly includes six
platens. Once the set of lens carriers are in position, with each
carrier supporting a container 24 thereupon, a lidstock sheet 26 is
moved into position between a heated mandrel 32 of the heat seal
apparatus and the containers 24. Lidstock 26 is preferably in the
form of a foil lid stock, which is preferably pre-perforated in a
conventional manner at a location corresponding to a location
between each individual lens carrier 14. The foil sheet is
typically a laminate of aluminum foil and a thermoplastic film,
such as a polyethylene. Lidstock 26 is preferably held by a foil
maneuvering mechanism which includes a pair of gripping fingers 28,
30. The fingers selectively move lidstock 26 from a retracted
position (not shown) to the inserted position (see FIGS. 1 and 2).
Preferably, the lidstock is held in position over the containers at
least until the heated mandrel contacts the lidstock to the surface
of the container at which time the fingers let go of the lidstock
and return to the retracted position. In another embodiment, the
fingers can hold the lidstock in place until the heat sealing step
is complete. The heated mandrel 32 is selectively movable from an
upper, non-engaging position, as illustrated in FIGS. 1 and 2, to a
lower engaged position, thereby applying heat and pressure to a
predetermined portion of the lidstock 26 positioned over the
container for a predetermined time to create a heat seal and form a
sealed package. More specifically, lidstock 26 is heat sealed to
the annular flanges 39 of each of the respective containers 24.
Thereafter, the heated mandrel 32 is raised back up to the upper,
non-engaging position. The individual lens carriers 14, which each
now carry a sealed package (i.e., a container 24 heat sealed to
foil lidstock 26) joined by the foil sheet to the adjoining
packages to form a set of packages, are next advanced to a
downstream conveyor 34 for further processing, in a manner which is
known to those skilled in the art. In the preferred mode, six (6)
containers are sealed in each step, with two lidstock strips
covering three packages each.
[0034] Each cylinder 18 is in fluid communication with one or more
pressure transducers 36 to measure the pressure that is applied by
the heated mandrel 32 against the container when mandrel 32 is
moved to the lower, engaged position. The heat seal apparatus 10
further includes a controller 59 electrically connected to the one
or more pressure transducers and to the individual cylinders, and
is programmed with the acceptable predetermined range for the
pressures to be exerted in forming the heat seal. The controller
preferably comprises a processor or computer programmed to receive
the electrical signals from the one or more pressure transducers,
determines the pressure applied to the respective packages 24, and,
if necessary, controls one or more of the cylinders 18 to increase
or decrease the pressure applied to that container. Preferably, the
pressure applied by the heated mandrel 32 against the containers 24
is within the predetermined range. The range can be determined by
those skilled in the art depending on the material used for package
24, lidstock 26 and their respective thickness to ensure that a
proper seal is achieved. Because of the tolerances in the thickness
of the sealing flange 39 on the container 24 and the thickness of
the lidstock 26, by applying the heated mandrel to an individually
supported lens carrier at a pressure maintained within the
predetermined range, the present invention ensures that the proper
pressure is applied to each container so that lidstock 26 is
properly sealed to container 24 in the set. Thus, in the event one
of the pressure transducers senses a pressure out of the
predetermined range, the corresponding cylinder is controlled to
either rise or descend to increase or decrease respectively, the
pressure applied to that container to ensure a proper heat
seal.
[0035] Referring now to FIG. 6, in a currently preferred exemplary
embodiment, one pressure transducer 80 is used to measure the
pressure that is applied to each cylinder or lift 18. Each cylinder
18 is adjustable between an up position and a down position
dependent upon the position of a three-way valve 84. Three-way
valve 84 receives fluid pressure from a conventional source (not
shown) via source conduit 86. Valve 84 connects fluid line 86 with
either cylinder up conduit line 82 or with cylinder down conduit
line 88. It is noted that the pressure transducer 80 is tapped into
pressure line 82 to determine the pressure applied by all cylinders
18 when they are in the up position. An alarm (not shown) is
activated if the detected pressure is not within a predetermined
range. If the alarm is activated the array of packages, which were
in the heat sealer, are tracked for discard by the control
system.
[0036] Lidstock 26 can be provided with a lid registration mark 38,
which can be sensed by an optical sensor assembly within the heat
cylinder assembly to ensure that the lidstock 26 is properly
positioned within the heat seal assembly. Registration mark 38 can
be an aperture or transparent portion of the lidstock, such that an
optical signal from an optical transmitter 41 of the sensor
assembly is received by an optical detector 40 only when the
aperture is aligned with the optical signal path defined between
the transmitter and receiver. In place of the optical sensor
assembly within the heat seal apparatus 10, registration of the
lidstock may be done elsewhere, and the gripping arms 28 and 30 of
the lidstock maneuvering mechanism may be arranged to reliably
maneuver the lidstock to a predetermined location in proper
registration with the platen 16 and, thus, with the carriers 14.
Because the lidstock is preferably held during the heat seal step
the alignment preferably does not need to be checked after
sealing.
[0037] In the preferred embodiment, in the steps before the
lidstock is placed over the containers in the heat seal apparatus,
the lidstock (which preferably has most of the graphics pre-printed
on it) has some variable product information printed on it, e.g.,
the power, lot and expiration date of the product and the lidstock
is cut and perforated into strips according to the number of
containers to be heat-sealed into an array. The printing on the
lidstock can be done by any known method, including laser printing
or thermal printing, preferably by laser printing. The preprinted
graphics on the lidstock preferably provide areas in which this
information is to be printed, e.g., blank colored boxes. In the
preferred embodiment, shown in FIG. 7, a strip of lidstock 26 is
fed off a roll 91 under constant tension through lidstock buffers
92 in the direction shown by arrow B to the printing system 94, and
to the cutting or cutting and perforation system 96 which are
located in a line. Preferably, between these two operations is
located a vision system 95 which uses a portion of the graphics on
the lidstock 26 to check the registration of the lidstock. If, when
the strip of lidstock 26 is fed into the printing system 94 and
cutting and perforation system 96, the portion of the graphics is
not in its proper location, the vision system 95 communicates to
the control system 99 for the process that the lidstock is not in
the correct location and the control system 99 instructs the
lidstock feed rollers 97 to adjust the position of the lidstock
either in the plus or minus direction. By the use of the vision
system 95 the lidstock 26 is continuously checked and automatically
realigned. The vision system 95 can be located before and/or after
the printing system 94, and/or within the cutting and perforation
system 96, and/or in the heat-seal apparatus 10. However, in the
preferred embodiment, there is only one vision system 95, e.g., an
optical character verification system with location capability, and
it checks the laser printing quality at the same time it checks the
registration; therefore, it is preferably located after the
printing system 94. By locating the printing system 94 and the
cutting and perforation system 96 in a line in which the lidstock
26 is taut between them and under constant tension, the
registration of the lidstock 26 by the vision system 95 maintains
registration in both systems. Further, in the preferred embodiment,
by carefully controlling the lidstock 26 during the cutting and
printing steps and by holding the lidstock until the mandrel 32
contacts the lidstock 26 in the heat-sealing apparatus 10, checking
the registration of the lidstock within or after the heat-sealing
apparatus 10 is not necessary, and in the preferred embodiment is
not done.
[0038] Further, in the upstream conveyor 12, a conventional
inspection system may be used to ensure that a proper or
non-defective lens has been placed within each container 24. In the
preferred embodiment, the detection system described in commonly
assigned U.S. patent application Ser. No. 09/187,579 filed Nov. 5,
1998, entitled "Missing Lens Detection System and Method", VTN-423,
the disclosure of which is hereby fully incorporated by reference,
is upstream of the heat seal apparatus. If either a conventional
inspection system or the preferred detection system is used, if an
improper or defective lens has been placed within container 24, or,
for example, if no lens has been placed within container 24, the
carrier 14 supporting the container can be removed from the
assembly line (i.e., from conveyor 12) downstream of the inspection
station by a discarder arm 61 or the like, which is preferably
controlled by the computer for the process acting on information
from the detection system or inspection system. An acceptable
lens-containing container on a carrier can then be automatically
moved into the empty position left by the removed carrier before
the individual lens carriers 14 are moved into position before or
in the heat seal assembly 10. A device for automatically inspecting
contact lenses is described in U.S. Pat. No. 5,687,541 to Martin et
al., incorporated herein by reference.
[0039] In another embodiment, the heated mandrel 32 may comprise
plural individually actuated dies 70 (FIG. 5) controlled by
individual die cylinders 72, each of which individually applies
pressure to portions of the lidstock 26 and to a corresponding one
of the containers 24 housed in the carriers 14. In this embodiment,
the cylinders 18 engaged to the corresponding platens 16 are
replaced by the die cylinders 72, and the platen 16 may be a
conventional, single base supporting all of the carriers or a
single carrier holding multiple containers to be heat sealed. The
pressure in the die cylinders can be monitored by one or more
pressure transducers 36 as described above in connection with FIG.
2 or FIG. 6 and the controller 59 can be responsive to receipt of
electrical signals from the respective transducers to control the
individual die cylinders 72 to maintain the pressure applied to
each of the packages within the predetermined range, or if the
pressure is outside a set range the arrays can be tracked for
discard. Again, it is preferable to hold the lidstock in place over
the containers until the mandrel is moved to the engaging position
causing the lidstock to contact the containers.
[0040] In another aspect of the invention, there is provided an
embodiment that allows for variances in the heat seal area of a
package by providing means that allow the heat seal apparatus to be
flexible to the pitch or yaw in the plastic in the heat seal
area.
[0041] In the embodiments of the invention described earlier, the
heat seal apparatus positions the carriers carrying the containers
under the mandrel. The mandrel preferably comprises one or more
heat seal dies that are mounted on the heat sealing apparatus and
are used to seal the lidstock to one or more containers. The
containers are located under the mandrel so that each container is
aligned with a corresponding heat seal die. In the embodiments
previously described, sometimes it is difficult to maintain the
surface of the heat seal die and the surface of the platen onto
which the carrier is mounted exactly parallel to each other which
will negatively impact the sealing of the lidstock to the
container. The embodiment shown in FIGS. 8-13 provides a heat seal
apparatus comprising one or more compliant heads. The heat seal
apparatus 100 comprises an upper portion 330 and a lower portion
290. The upper portion comprises a heated mandrel 132. The lower
portion comprises a compliant head 291 comprising a platen 116,
that allows each platen 116 (and therefore the container on each
platen) to move limited distances preferably in the horizontal,
vertical, pitch and yaw directions so that the surface 233 of the
heat seal die 234 that contacts the lidstock on each container and
the surface 296 of each platen that carries each container are
parallel to one another. This provides for the most consistent and
reliable sealing of the lidstock to the container.
[0042] Each compliant head 291, shown individually in FIG. 12,
comprises a platen 116 and movement means that provides for the
movement of the platen during use so that the surface of the platen
and the surface of the sealing die are aligned and preferably
parallel to one another. The movement means as shown in FIGS. 10,
11, 12 and 13 is a spring 292 one end of which is preferably
attached to the platen 116, preferably at the surface 297 of the
platen 116 opposite the carrier contacting surface 296 of the
platen 116. The spring can be attached to the platen (and/or the
platform) via a boss in the inside diameter at the ends of the
springs, or by welding, fasteners, or any way known to a persons of
ordinary skill in the art. Alternative means that provides movement
of the platen could be a shock, e.g. gas shock, and a ball bearing
to support the platen. The compliant head 291 preferably also
comprises a platform 294 to which the other end of the spring 292
is attached. Each compliant head 291 is preferably constructed as a
separate part so that if a compliant head wears or is defective it
can easily be removed from the lower portion of the sealing
apparatus 290 and replaced.
[0043] Each compliant head 291 is attached to a support 299 via a
screw 293. Preferably screw 293 is a fine threaded adjustment screw
that is preferably also used to pre-load the spring that is to
compress the spring. The compliant head is calibrated such that for
a given compression distance (preferably 2 mm) the desired force is
achieved (preferably 400-500 lbs depending upon the shape of the
package.) The spring 292 must be designed so that it is in its
elastic range within the required deflection. This will typically
yield millions of cycles before failure.
[0044] The compliant head 291 preferably further comprises means to
hold the spring in a compressed state. The means to maintain the
spring in a compressed state comprises upper lips 301 that are
attached to side supports 300. The side supports are located on
opposite sides of each compliant head 291 and attached to support
291. The lips 301 constrain the platens 116 and define the maximum
vertical position of the platens (the compliant head), and with the
support 299 are means to maintain the spring under constant
compression. When the compliant head is mounted onto the support
and between the side supports, preferably the spring is under a
compression force.
[0045] In the preferred embodiment as shown in more detail in FIG.
13, in addition to the movement of the platen by the vertical
compression of the spring, movement of the platen can be any
direction; however additional means to limit this movement are
preferably provided. In the preferred embodiment, as shown in FIG.
13, the means to limit the movement are the lips 301, and one or
more pins 303 that are attached to or are part of side supports 300
that are received into one or more slots 304 in each platen 116. As
shown each side support 300 has a pin 303 for each platen 116, and
each platen 116 has two slots 304 on opposite sides to receive the
pins 303. The pins 303 and slots 304 are sized to allow the platens
to tip back and forth, and to pivot left and right. In use when the
platen of the compliant head carrying a container is in pressurized
contact with a lidstock and the surface 233 of the heat seal die
234, the platen and therefore the container and lidstock conform to
the plane of the surface 233 of the heat seal die 234. As shown the
platen 116 and the contacting surface 233 of the heat seal dies 234
can be up to 0.3 mm from parallel prior to contact, and when in
contact the compliant head will allow the platen to move in an
angular direction to provide for planar alignment of surfaces 296
and 233 during the process of heat seal.
[0046] The preferred mandrel is a heat seal die block 101 as shown
in FIG. 14. The heat seal die block 101 comprises heat seal dies
234 that comprise a raised area 105 the surface 233 of which when
in use, contacts, heats, and presses the lidstock against and into
the sealing flange 39 which is preferably a raised area on the
surface of the container 24. As shown in FIG. 14, the raised
circular area 105 is useful to adhere lidstock 26 to a round
sealing flange 39, similar to the one shown in FIG. 3.
[0047] When the compliant heads are assembled, it is preferred that
the springs are used within their working elastic region and the
springs can be designed to be repeatable in force for a given
distance. When in use, the platen will be compressed a known
distance; therefore, the screw can be used to adjust the preload on
the spring until the force requirement is met. Each spring is
calibrated in this way to provide the same compression force and
provide for repeatable deflection.
[0048] In the preferred embodiment shown in FIGS. 8 and 9, the
lower portion 290 comprises the means to move the upper portion and
the compliant head into contact with the container between the
platen and the heat seal dies 234. In an alternative embodiment the
upper portion could be provided with means to move the upper
portion into contact with the lower portion. As shown, the means
are a single lift 335 that operates on the support 299 to move all
six compliant heads mounted on the support upwards into contact
with the mandrel 132 of the upper portion 330. The lift 335, e.g.,
a hydraulic or pneumatic (i.e., fluid) cylinder preferably a
pneumatic cylinder, more preferably an air cylinder, most
preferably an air cylinder having a large bore. The upper portion
is attached to stationary frame 295. The lower portion 290 is also
attached to the same frame 295. The compliant head is movably
attached via the lift 335 to the frame 295. The compliant head
moves vertically when moved by the lift 335. The lift is attached
to the compliant head by bolting the lift to the support 299.
[0049] In operation, the compliant head carrying the containers is
moved by the lift into contact with the mandrel. Preferably the
compliant head is overdriven to a dead stop at a point that will
force the springs to be compressed a required distance,
approximately 1-2 mm. In this way minor fluctuations in the lift's
pressure will not detrimentally impact the seal of the lidstock to
the container. Therefore, if the lift is brought to a stop short of
the lift's driving limit, the springs in the compliance head are
compressed the required distance against the manifold, and any
force in excess of that required by the springs would be absorbed
by the dead stop. In this way we have a finely controlled and
calibrated force (the springs) and a main driving force which is
very robust (the lift, a cylinder) which drives the calibrated
force to its calibrated position. At the point at which the springs
are compressed, the compliant heads can each adjust themselves
horizontally, vertically and in the pitch and yaw directions to be
parallel to the mandrel. In this way the plane of the container and
the plane of the heat seal die will be parallel or differ by less
than 2 degrees from parallel.
[0050] This embodiment is an improvement over the other
embodiments, because it provides individual compliance in multiple
directions, vertically, horizontally, and angularly in the pitch
and yaw directions. Another benefit is that maintenance is
simplified by decreasing the number of lifts or air cylinders,
which sometimes have failure of seals or variances in airline
pressure. However, the compliant heads of this invention can be
used in the previously described embodiments having multiple lifts
to provide additional compliance to those embodiments. The
compliant heads described and shown herein could be attached to
individual lifts, instead of to a support and a single lift as
described above.
[0051] Further, the compliant head could be used as the mandrel
with individual heat seal dies attached to each compliant head
instead of individual platens as described and shown above. Either
the upper or lower portions or both portions of the heat sealing
apparatus could be moved by one or more lifts (and individual lifts
for each heat seal die, if desired) as described above to overdrive
the springs in the compliant head to provide proper alignment of
the heat seal dies and the platens (containers).
[0052] In this embodiment it is preferred to use high-pressure to
yield much faster seal times, improved seal integrity, and minimal
skinning (a negative condition apparent when opening a primary
package leaving the plastic substrate of the foil attached to some
extent on the primary package. The force is preferably greater than
350 lbs.
[0053] Another aspect of this invention is the provision of an
improved heat seal die that provides improved thermal
characteristics. The heat seal die of this invention maintains its
temperature very close to the temperature necessary to heat-seal
the lidstock to the container at all times, even just after a
heat-sealing step. In the preferred embodiment this temperature is
approximately 200-240.degree. C. In earlier embodiments, there was
a lag time of greater than 3 seconds between sealing packages to
provide time for the heat seal die to heat up to a temperature
necessary for heat-sealing. To attempt to decrease the lag time,
more conductive materials were used for the heat seal die; however,
the conductive materials are expensive and easily damaged.
[0054] In this invention, an advanced wafer heater that has very
high wattage (developed and marketed by Tayco Engineering for use
in the aerospace industry) is used to heat the heat seal dies. By
using direct application of the wattage needed to seal the package
rather than the thermal momentum of the die, the heat seal dies are
maintained at the necessary temperature, and the lag time for the
heater to increase the temperature of the heat seal die is
decreased significantly to less than 1 second. Additionally,
because the heater is so efficient, it allows for the use of a heat
seal die material that is best suited for a manufacturing
environment, that is stainless steel, more preferably hardened
stainless steel. The stainless steel die is very durable.
[0055] The improved heater also overcomes the negative impact that
energy wicking has on the heat seal when the lidstock that is heat
sealed comprises a foil layer. When the shape of the lidstock
having a foil layer is not equal on all sides surrounding the shape
of the heat seal die there is uneven wicking away of heat from the
heat seal die by the lidstock. More energy is wicked away where
there is more foil, causing the resulting seal of the lidstock to
the container to be "lighter" where substantial heat was wicked
away. Prior to this invention to compensate for this, the package
has been sealed to provide sufficient seal on the side with more
foil which has resulted in over-sealing the side with less foil.
This has caused problems with skinning and other difficulties when
opening packages.
[0056] To overcome this problem, the heat seal dies can be modified
to even out the energy by providing an extra thermal mass to the
heat seal die in the areas of the heat seal die that will contact
the lidstock where there is a greater amount of foil to wick the
heat away from the heat seal die. To determine how much mass to
provide to the heat seal die, the efficiency of the heater (any
heater), and the amount of foil (available to wick heat away from
the heat seal die) around the area of the lidstock that the heat
seal die will contact, and the thermal conductivity of the heat
seal die material and foil must be considered. FIG. 14 shows the
thermal mass 407 useful for providing more energy from the heater
(not shown) into the side 408 of the heat seal die 234 that
contacts the lidstock with a bigger area of foil available to wick
the energy from the heat seal die which results in an even seal of
the lidstock to the container.
[0057] Having described the presently preferred exemplary
embodiments of an apparatus for automatically packaging contact
lenses in accordance with the present invention, and related
inventions, it is believed that other modifications, variations and
changes will be suggested to those skilled in the art in view of
the teachings set forth herein. It is, therefore, to be understood
that all such modifications, variations, and changes are believed
to fall within the scope of the present invention as defined by the
appended claims.
* * * * *