U.S. patent application number 11/879744 was filed with the patent office on 2008-02-21 for digital transfer method for printing on a target surface.
Invention is credited to James Cowan.
Application Number | 20080043087 11/879744 |
Document ID | / |
Family ID | 38957587 |
Filed Date | 2008-02-21 |
United States Patent
Application |
20080043087 |
Kind Code |
A1 |
Cowan; James |
February 21, 2008 |
Digital transfer method for printing on a target surface
Abstract
A method for creating and transferring digitally created images
on a film to a target surface via heat and/or pressure transfer
using a modified large-format digital printer. The method generally
comprises the steps of modifying a large-format digital printer to
convert it from heat fused toner printing to cold toner printing,
preparing a transfer film, creating a digital image, applying a
release layer onto the transfer film, printing the image onto the
release layer on the transfer film in a reverse mirror-image
manner, applying an adhesive overtop said image, and pressure
transferring the image onto the target substrate and peeling away
the transfer film to selectively leave the image on the target
substrate. The present method results in a cleaner, clearer more
eye-catching graphic deposited in a more robust, wear-tolerant
manner on a wider variety of substrates including rough and porous
materials such as leather.
Inventors: |
Cowan; James; (Surrey,
GB) |
Correspondence
Address: |
Ober, Kaler, Grimes & Shriver;Attorneys at Law
120 East Baltimore Street
Baltimore
MD
21202-1643
US
|
Family ID: |
38957587 |
Appl. No.: |
11/879744 |
Filed: |
July 18, 2007 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
60831838 |
Jul 19, 2006 |
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Current U.S.
Class: |
347/213 |
Current CPC
Class: |
C12N 9/0083 20130101;
C12N 15/8247 20130101 |
Class at
Publication: |
347/213 |
International
Class: |
B41J 2/325 20060101
B41J002/325 |
Claims
1. A method for creating images on a film for transfer to a target
surface via heat and/or pressure transfer, comprising the steps of:
loading a transfer film coated with a release layer into a digital
printer; printing a digital image onto said release layer; applying
an adhesive overtop said printed image; and heat and/or pressure
transferring said image onto a target substrate, peeling away said
transfer film selectively leaving only the image adhered to said
target substrate.
2. The method for creating images on a film according to claim 1,
wherein said step of loading a transfer film coated with a release
layer into a digital printer comprises loading a transfer film
coated with a textured-surface release layer into said digital
printer.
3. The method for creating images on a film according to claim 1,
wherein said step of loading a transfer film coated with a release
layer into a digital printer comprises loading a transfer film
coated with an anti-microbial release layer into said digital
printer.
4. The method for creating images on a film according to claim 1,
wherein said step of loading a transfer film coated with a release
layer into a digital printer comprises loading a transfer film
coated with a UV-absorbent release layer into said digital
printer.
5. The method for creating images on a film according to claim 1,
wherein said step of loading a transfer film coated with a release
layer into a digital printer comprises loading a transfer film
coated with a phosphorescent release layer into said digital
printer.
6. The method for creating images on a film according to claim 1,
wherein said step of loading a transfer film coated with a release
layer into a digital printer comprises loading a transfer film
coated with a fluorescent release layer into said digital
printer.
7. The method for creating images on a film according to claim 1,
wherein said step of heat and/or pressure transferring said image
onto a target substrate loading a transfer film coated with a
release layer into a digital printer comprises applying a
differential pressure to the transfer film in an image area versus
outside an image area to effect selective release of said
image.
8. The method for creating images on a film according to claim 7,
wherein said step of applying a differential pressure comprises
applying pressure to said transfer and relying on a differential
thickness of image toner in an image area versus outside an image
area to effect selective release of said image.
9. A method for creating and transferring digitally created images
on a film to a target surface via heat and/or pressure transfer
using a digital printer, comprising the steps of: modifying the
digital printer to convert from double fused toner printing to
single fused toner printing; preparing a transfer film; creating a
digital image; applying a release layer onto said transfer film;
printing the image onto the release layer on said transfer film;
applying an adhesive overtop said image; and heat and/or pressure
transferring said image onto a target substrate, peeling away said
transfer film selectively leaving said image only on said target
substrate.
10. The method for creating images on a film according to claim 9,
wherein said step of heat and/or pressure transferring said image
onto a target substrate loading a transfer film coated with a
release layer into a digital printer comprises applying a
differential pressure to the transfer film in an image area versus
outside an image area to effect selective release of said
image.
11. The method for creating images on a film according to claim 10,
wherein said step of applying a differential pressure comprises
applying pressure to said transfer and relying on a differential
thickness of image toner in an image area versus outside an image
area to effect selective release of said image.
12. A heat and/or pressure transfer, comprising: a disposable
transfer substrate; an image release coating on the substrate; a
digitally printed ink image on the image release coating; and a
pressure and/or heat activated adhesive applied over said printed
image; wherein said transfer is differentially thicker in an area
of said digitally printed ink image than outside side image
area.
13. The heat and/or pressure transfer according to claim 12,
wherein said release layer comprises wax.
14. The heat and/or pressure transfer according to claim 12,
wherein said release layer comprises lacquer.
15. The heat and/or pressure transfer according to claim 13,
wherein said release layer comprises wax.
16. The heat and/or pressure transfer according to claim 12,
wherein said release layer comprises a textured-surface release
layer.
17. The heat and/or pressure transfer according to claim 12,
wherein said release layer comprises an anti-microbial
ingredient.
18. The heat and/or pressure transfer according to claim 12,
wherein said release layer comprises a UV-absorbent ingredient.
19. The heat and/or pressure transfer according to claim 12,
wherein said release layer comprises a phosphorescent
ingredient.
20. The heat and/or pressure transfer according to claim 12,
wherein said release layer comprises a fluorescent ingredient.
Description
CROSS-REFERENCE TO RELATED APPLICATION(S)
[0001] The present application derives priority from U.S.
Provisional Application Serial No. 60/831,838 filed 19 Jul.
2006.
BACKGROUND OF THE INVENTION
[0002] 1. Field of the Invention
[0003] The present invention relates to digital printing and, more
specifically, to a method for transferring digitally created images
from film to a target surface via heat and/or pressure
transfer.
[0004] 2. Description of the Background
[0005] Traditional offset printing processes involve a number of
expensive and time-consuming steps, such as plate imaging and
mounting. A number of manufacturers are now selling digital
printers that print documents directly from electronic files to
paper, or a variety of other substrates. These digital printers
greatly simplify the printing process. Other than buying a digital
printer and preparing a design to be printed, there are no other
start-up costs or steps involved in the digital printing process.
Thus, these printers allow cost-effective high quality shorter
print runs. Both the form and content of each consecutive print can
be different. Currently, only digital printing technology can
provide the level of personalization and customization demanded by
many manufacturers.
[0006] Current purveyors of digital printing equipment include
Xeikon, Kodak, Dotrix, HP and Xerox. Xeikon in particular targets
the high-end segment of the digital printing market with printing
presses that deliver excellent print quality and
cost-effectiveness. Xeikon caters to an "on demand" business model,
print shops that cater to customers who order large quantities of
color documents that require delivery by the next day. The Xeikon
digital printer, in combination with the Xeikon Digital Front End
software, offers a print quality with superb color matching and
perfect front to back registration. The result is a consistent
high-quality, full-color print with astounding richness and depth
of color that sets the standard for the rest of the market.
[0007] The Xeikon print series are configured for successive
application of four colors plus white, if required, to a medium as
it travels across the printing cylinders. When printing to a 4
color-process toner based output printing system, there are four
colors (Cyan, Magenta, Yellow, and Black, the combinations of which
recreate any photograph or color in a desired spectrum. For
example, a full color photograph of a child in a red dress would be
broken down into millions of small pixels-each pixel has a 4-color
value assigned to it. A pixel that is in the position in the
child's face would have a value of Cyan-5%, Magenta-42%,
Yellow-34%, and Black-10%. The typical shade of black will be
Cyan-75%, Magenta-68%, Yellow-67%, and Black-90%. In a five color
press a fifth color can be used as a specialty toner color or
white. For example, a layer of white can be applied as the fifth
color to enhance the colors and give the print opacity. This way,
the substrate doesn't show through the image. There is the
potential for even more colors or additional specialty toners
simply
[0008] In a conventional direct electrostatic color printing
system, a plurality of rotating cylinders are statically charged by
charging electrodes, and LEDs remove the charge selectively
according to a color-separated pattern. The pattern is typically
generated by the front end of the print engine taking the image
file sent to the front ends and converting into a digital format
that the engine will print The color-separated pattern is then
imparted to the surface of the respective cylinders by the cylinder
being completely charged with static charge and the this charge
being removed by exposure to LEDs as the cylinder rotates past
these LEDs. The LEDs are switched on and off according to the
pattern required. The charged cylinders continue to rotate past a
toner applicator that deposits toner on the pattern. Toner is
attracted and transferred, according to the charged pattern or
image, from the toner applicator onto the cylinder. Next, a print
media is run across the cylinders and the toner is deposited onto
the media according to the pattern, e.g., the pattern or image is
printed on the material. The foregoing process can be adapted to a
variety of different print media at speeds of 100 images per minute
or faster.
[0009] On the other hand, rub-on image transfers are well-known and
include letters and numerals in different type faces which can be
transferred from the face of the film on to the target surface
(e.g. a drawing on paper) by placing the image face against the
paper and rubbing down or burnishing the back of the film so that
the letter or numeral becomes attached to the target surface and
detached from the film.
[0010] There have been several attempts to extend the digital
printing process as described above to transfers, though such
attempts have involved more or less complicated procedures and the
use of particular materials with limitations as to the nature of
the final target surface.
[0011] U.S. Pat. No. 6,656,306 to Mabbott issued Dec. 2, 2003 shows
a method for the preparation and application of pressure and heat
applied image transfers. An image layer is applied to an image area
of an image release surface, and a pressure and/or heat activated
adhesive layer is overcoated. The adhesive layer adheres more
strongly to the image layer than the image layer does to the
release surface, and so with the application of pressure and/or
heat, the dried adhesive layer attaches only in the image area to
the target surface and the adhesive layer is peeled off except for
the image area which is left attached to the target surface.
[0012] It would be greatly advantageous to extend the Mabbott
concept to provide a cleaner, clearer more eye-catching
graphic.
SUMMARY OF THE INVENTION
[0013] It is therefore an object of the present invention to
provide a method for the preparation and application of pressure
and heat applied image transfers by modifying a large-format
digital printer to convert it from heat fused toner printing to
cold toner printing, utilizing a very narrow dye range for all
coatings, and further making use of the differential thickness
between the areas of a release layer where there is toner present
and where there is no toner such that adhesive applied to the
release layer over the image adheres more strongly to the image
than the image does to the release layer. Thus, when transferred to
a target surface with the application of pressure and/or heat, the
dried adhesive layer attaches only in the image area to the target
surface and the adhesive layer is peeled off except for the image
area which is left attached to the target surface. This produces a
high-resolution four color graphic with white: a cleaner, clearer
more eye-catching graphic than previously possible.
[0014] In accordance with the foregoing objects, the present
invention is a method for creating and transferring digitally
created images on a film to a target surface via heat and/or
pressure transfer using a modified large-format digital printer.
The method generally comprises the steps of modifying a digital
printer to convert it from a front and back heat fused toner
printer, to a back fuser toner printer, preparing a transfer film,
creating a digital image, applying a release layer onto the
transfer film, printing the image onto the release layer on the
transfer film in a reverse mirror-image manner, applying an
adhesive overtop said image, heat and/or pressure transferring the
image onto the target substrate and peeling away the transfer film
to selectively leave the image on the target substrate. The present
method results in a cleaner, clearer more eye-catching graphic
deposited in a more robust, wear-tolerant manner on a wider variety
of substrates including rough and porous materials such as
leather.
BRIEF DESCRIPTION OF THE DRAWINGS
[0015] Other objects, features, and advantages of the present
invention will become more apparent from the following detailed
description of the preferred embodiment and certain modifications
thereof when taken together with the accompanying drawings in
which:
[0016] FIG. 1 is an exploded diagram showing the layers of an
exemplary image transfer 2 according to the present invention.
[0017] FIG. 2 is a block diagram of the process steps for making
and applying the above-described transfer 2.
[0018] FIG. 3 is a diagram of the components of an exemplary Xeikon
digital printer that are removed as per the necessary modification
of the present invention.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0019] The present invention is a digitally-printed transfer
bearing a digitally created image that can be heat and/or
pressure-applied to a target surface, and a method for transferring
the digitally created images from film to a target surface via
digital printing and heat and/or pressure transfer.
[0020] The process employs a modified digital printer (converted
from a double sided fusing printing process to a back fusing web
printing process) to create an image on transfer film subsequently
coated with adhesive that is then heat and/or pressure-applied to a
substrate to yield a high-resolution four color graphic with
white.
[0021] The basic fabrication steps comprise 1) coating one side of
a disposable base transfer film (or carrier) with a releasable
coating; 2) digitally printing one or more images overtop the base
transfer film in reverse-image format; and 3) applying an adhesive
coating over the image.
[0022] The result is a roll of pre-printed transfers. In accordance
with the present method for transferring the digitally created
images from film to a target surface, 4) the base transfer film is
indexed over a target substrate (image down and showing through the
film) and heat and/or pressure is applied to the base transfer film
to adhere the image to the target substrate. The base transfer film
is peeled from the target substrate and is discarded, leaving a
high-resolution color graphic image on the target substrate.
[0023] The method is described in detail below with various
options, and in all cases the method is unique because when the
image is transferred there is "selective release", meaning that
there is transfer to the target substrate only in a pre-determined
area (most commonly in the specific area of the print image, though
for some applications it may be desirable to have a release that
includes non-imaged areas), despite the adhesive coating which may,
and indeed, usually exceeds the borders of the printed image. This
selective release improves the quality of the transfer because
there are no unsightly borders or margins around the image, and
holes and gaps in fairly complex images are not filled in.
[0024] FIG. 1 is an exploded diagram showing the layers of an
exemplary image transfer 2 according to the present invention. The
image transfer 2 includes a disposable base transfer film 11. This
can be any suitable transfer carrier formed of plastic or non-woven
material and that is capable of being passed as a web through the
production machinery. For example, the presently preferred transfer
film 11 is polyester teraphthlate (PET). In accordance with one
optional feature of the present invention, the transfer film 11 may
be preformed with distinct surface patterns or texture to give the
final transfer a textured aesthetic.
[0025] An image release layer 12 is uniformly applied onto the base
transfer film 1 1. Image release layer 12 may be, for example, a
wax, lacquer, or combination of wax and lacquer, with or without
specific additives. The application of the image release layer 12
may be attained by applying the wax and/or lacquer onto the base
transfer film 11 in individual coats from either solvent or
waterborne solutions or suspensions. It is known from experience
that the final parameters of the coating can be adapted to any
requirement by the changing coating weights, the addition or
substitution of resins, waxes and wax solutions, and there are many
conventional coating methods that can be used to achieving a
desired coat weight. The appearance of the final coating can be
full gloss or be matted down to the required level by the addition
of matting agents. When applied the release layer 12 must be
uniform, and free from all coating defects and application patterns
(except where a coating pattern is an intended aspect). The
presently-preferred release layer 12 comprises a lacquer mixture of
commercially available polymethyl methacrylate resin with a
commercially available wax suspension (BYK 151 ex-Samual Banner).
The ratio of resin to wax is on the order of 80% to 95% resin to 5%
to 20% wax. These two components are provided in a 5% to 15% solid
solution (depending on method of application) in a butanone and
toluene solvent blend (of which toluene is around 10% of the total
solvent). The release layer coating is then forced air-dried giving
a dry coat weight coat weight of 1.15 to 1.35 grams per square
meter.
[0026] The image 13 itself is then digitally printed with a four
color graphic (as will be described) on the transfer film 11
(overtop release layer 12). The digital printer may employ either
electro-ink or dry powder toner, and otherwise conventional print
techniques. Preferably, a registration mark is printed at this same
time, and when desired the four-color image 13 (and registration
mark) is then overprinted with a white background 14.
[0027] Finally, a pressure and/or heat activated adhesive layer 15
may be applied evenly over the whole of the web, both where there
is image and no image, or may be selectively applied only in the
image area. Presently, the adhesive layer 15 is applied in line
directly after the printing step using a 3.5% to 4% solution of
commercially available polyamide (Lioseal V 7036 ex-Henkel) in a
solvent system, which is predominately Isopropyl alcohol. This
solution is then coated onto the image 13 and/or transfer film 11
by a wire wound rod at a dry coating weight of 0.2 to 0.3 grams per
square meter, the applied coating being forced air-dried.
[0028] To then transfer the digitally created image from the
transfer film 11 to a target surface, the base transfer film 11 is
placed on a target substrate and is indexed in position using the
index lines (image down and showing through the film). The adhesive
layer is then heat and/or pressure-fused to a subject material and
the image itself 13 adheres more strongly to the material than does
the image release layer 12. Thus, when the image transfer film 11
is applied image-down to a target substrate by application of
pressure and/or heat (as will be described), the dried adhesive
layer 15 attaches to the target substrate only in the image 12 area
but is otherwise retained by the transfer film 11 ("selective
release"). To then apply the transfer 2, the image transfer film 11
is peeled off the target substrate together with the dried adhesive
layer 15 except for the image area which is left attached to the
target substrate by the pressure and/or heat activated adhesive
layer 15. For this to happen, the thickness of the non-printed
areas of release layer 12 and adhesive layer 15 must be thinner
than printed areas containing the release layer 12, image 13 and
adhesive layer 15 such that more pressure is exerted where there is
image to the target substrate than where there is no image. The
characteristics of the image release layer 12, the adhesive layer
15 and the image layers 13, 14 are selected so as to work with a
wide variety of target substrates, including textured and porous
materials such as leather to give this selectivity.
[0029] FIG. 2 is a block diagram of all necessary process steps for
making and applying the above-described transfer 2.
[0030] Step 1: Modify Digital Printer
[0031] This printer can be any conventional digital printer that
uses either ElectroInk.TM. or dry powder toner, or other
conventional print techniques. For example, a Xeikon.TM. large
format digital printer is suitable. This and most other large
format digital printers employ heater roller assemblies and fusers
generally contained within a protective housing. A toner image is
transferred to a sheet or web and is then fixed to the web by heat
and/or pressure. Typically the paper is transported in a nip
between the fuser and pressure roller, which are rotating. Thermal
radiation from a lamp heats the fuser roller, causing the toner on
the web to melt and press into the web fibers. In accordance with
the present invention, the printer is modified to essentially
convert it from a front and back fuser system to a back fusing web
printing process. The modification initially entails disabling the
heaters in the infeed module removal of the front fusers (substep
22) and removal of the GEM rollers 24. Specifically, for a Xeikon
digital printer, the front fusers and part nos. CNS-1262-01 5208
32D (Gem Roller) would be removed as seen in FIG. 3. In addition,
the print color order is changed from the conventional CMYK to
KMCY
[0032] Step 2: Prepare Web
[0033] The current process uses a plastic web in roll form for the
base transfer film 11 of FIG. 1 and pre-coats this with the release
layer 12 which may be a releasing lacquer, a wax, a release
coating, or a combination of any of these as described above. At
substep 42 it is necessary to mix the releasing layer (lacquer,
wax, coating, or combination of any of these). The lacquer, wax and
release coating are custom-mixed to create the correct release
factor for a range of heat and pressure used. A suitable wax
release can be mixed with a combined acrylic nitrocellulose
overlacquer for this purpose.
[0034] If desired, the release layer 12 may be texturized or mixed
with specific additives, such as UV absorbers or biocides, to give
the release layer specific properties.
[0035] For example, the release layer 12 may be texturized with a
distinct carrier surface pattern (matte or scratch). Since the
image is printed onto the release layer 12 and is then transferred,
the net effect is to impart the surface pattern onto the surface of
the transfer. Most any texture or pattern that can be made to the
surface of the release layer 12, for example, embossing, etching or
addition of a solid component, e.g. silica. In each case this is
transferred when it is applied to the target substrate. These
changes can be aesthetic for example, matte, brushed effect,
geometric pattern, regular pattern or random pattern. The effect
can also be subtle such as wording, images or patterns that are
only visible with light shining on the surface at a particular
angle, thereby serving as a simple security device.
[0036] As another example, the release layer 12 may contain a
functional additive that confers a property to the transfer 2 that
is not present in the transfer without the additive. For example
the addition of 1% of an anti-microbial additive such the transfer
surface as applied to a target will inhibit bacteria. Inorganic,
silver-based antimicrobials are generally recognized as safe and
are well suited for this purpose.
[0037] The addition of a small percentage (less than 10%) of a UV
absorber will protect the toner image from degradation in color
intensity due to prolonged exposure to direct sunlight.
[0038] The addition of a phosphorescent or fluorescent additive
will make the transfer "glow" when UV light is shined onto it. This
addition can be used in conjunction with the above-described
surface pattern, making the effect easier to detect.
[0039] Step 3: Prepare Image
[0040] The image is designed into a vector image file, or scanned
into a raster image file, in both cases using four color CMYK
pixilation.
[0041] As seen at substep 32, the emblem graphic design may be
generated using computer drawing software. This is generally
accomplished using graphics programs such as well-known Adobe
Illustrator.TM., Photoshop.TM., etc. Such software is capable of
calculating the image dimensions from the design, and colors are
chosen from a selectable palette. Photoshop software developed by
Adobe uses a palette technique in which the image data is coded and
compressed to a prescribed number of colors (a range of from 256 to
16M colors depending on the selected palette). The image file can
be manipulated as desired to resize/rescale, redraw or alter the
coloration. The final image is then saved as a CMYK raster image
file.
[0042] Step 4: Print Image
[0043] Given a prepared image, at substep 44 the image is printed
directly from the raster image file and at substep 46 an additional
toner drum of white toner (W) is used to print a white overprint.
The process imprints electrostatically charged toner or inkjet
images onto the base transfer film 11. The process prints the
desired image, laying on colors in registration patterns in the
order Black, Magenta, Cyan, Yellow (KMCY), and finally White,
instead of the CMYK patterns that are applied by an unmodified
Xeikon. The printing of a white layer of color at substep 66 is
unique to the invention and this improves contrast by filling in
blank areas. When working on the design computer white is seen as
black. White cannot be seen on the screen. The black image (the
part we want to be white) is given a specific reference, for
example, pantone 100. This specific reference number is added as a
5.sup.th color that the Xeikon combines with the normal CMYK colors
of the design, and yet printing this reference color as white as it
has been programmed to do.
[0044] Step 5: Apply Release Layer
[0045] Next, at step 5, the mixed release layer 12 is applied to
the plastic transfer film 11. The release layer 12 is applied over
the whole surface of the base transfer film 11 using conventional
coating machine.
[0046] Step 6: Apply Adhesive
[0047] At step 6 a water or solvent based adhesive is applied over
both the image (with nor without white) and the areas that do not
contain a printed image. These areas may include parts of the image
that have intentionally been left clear of print for example
between numbers, backgrounds to let the substrate be seen through
the print, etc. The transfer 2 is now complete.
[0048] Step 7: Apply finished Transfer 2
[0049] Finally, at step 7, the image transfer 2 may be applied to a
wide variety of materials including rough and/or porous materials
such as leather. At substep 72 the image 13 may be transferred to
the substrate material by a roller-to-substrate process, or through
a heat-stamping process, in both cases using conventional presses.
In both cases the differential pressure of the transfer film 11
with toner versus the transfer film 11 without toner is the factor
that controls the selective release according to the present
invention. More specifically, at substep 74 the dried adhesive on
the printed area of the image 13 encounters more pressure due to
the additional thickness added by the toner, and thus the printed
areas of image 13 attach to the target material. After the transfer
film 11 contacts the target substrate, the transfer film 11 may be
peeled away. The printed image 13 transfers to the target substrate
as the web separates. The adhesive on the printed area attaches to
the target surface and pulls the printed image off the transfer
film 11 and onto the target substrate. The process does not leave a
"lacquer halo" around the printed images as in conventional
transfer processes.
[0050] Where a heat-stamping process is used, the stamping press
may be used a second time directly onto the transferred image to
imbed the printed image into the selected substrate.
[0051] This differential pressure is obtained by the difference in
thickness between the areas of the film that are imprinted with the
image 13 and areas where there is no image. Although it is
imperceptible to the naked eye, the transfer 2 is thicker in the
areas where the toner has been applied. The image is transferred
selectively through the interaction of the release layer, image and
adhesive and the target substrate. The release layer and adhesives
being specifically formulated to exploit this differential
pressure.
[0052] Having now fully set forth the preferred embodiments and
certain modifications of the concept underlying the present
invention, various other embodiments as well as certain variations
and modifications thereto may obviously occur to those skilled in
the art upon becoming familiar with the underlying concept. It is
to be understood, therefore, that the invention may be practiced
otherwise than as specifically set forth herein.
* * * * *