U.S. patent application number 11/723980 was filed with the patent office on 2008-05-15 for contoured clamshell container.
This patent application is currently assigned to DOPACO, INC.. Invention is credited to James A. Yocum.
Application Number | 20080110966 11/723980 |
Document ID | / |
Family ID | 39368263 |
Filed Date | 2008-05-15 |
United States Patent
Application |
20080110966 |
Kind Code |
A1 |
Yocum; James A. |
May 15, 2008 |
Contoured clamshell container
Abstract
A clamshell container comprising a tray and a cover formed from
a blank; the tray including a bottom and four curved side walls
foldable upward from the four edges of the bottom along arcuate
fold lines, the tray walls having defined corners inwardly offset
relative to the center points of the walls; and a cover provided
with corresponding walls, at least three of which are folded from
arcuate fold lines along corresponding edges of a cover top panel
and which define depending arcuate cover walls and a cover with a
maximum width at transverse centerlines between opposed sets of
walls and minimum widths at corners defined by the cover walls; the
cover pivotally closing over the tray with the arced walls of the
tray received within the arced walls of the cover and engaging
therewith.
Inventors: |
Yocum; James A.; (West
Chester, PA) |
Correspondence
Address: |
DENNISON, SCHULTZ & MACDONALD
1727 KING STREET, SUITE 105
ALEXANDRIA
VA
22314
US
|
Assignee: |
DOPACO, INC.
|
Family ID: |
39368263 |
Appl. No.: |
11/723980 |
Filed: |
March 23, 2007 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
60857801 |
Nov 9, 2006 |
|
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Current U.S.
Class: |
229/114 |
Current CPC
Class: |
B65D 5/667 20130101 |
Class at
Publication: |
229/114 |
International
Class: |
B65D 5/00 20060101
B65D005/00 |
Claims
1. A clamshell container of foldable paperboard particularly
adapted for reception of a heated foodstuff, said container being
configured for reduced utilization of paperboard and enhanced
retention of heat, said container comprising a tray and a cover,
each of generally rectangular configuration, said tray having a
bottom with opposed side edges and opposed front and rear edges,
said tray further including opposed laterally spaced front and rear
walls folded upwardly respectively from said front and rear edges
of said tray bottom, the laterally spaced relation between said
front and rear walls being at a maximum at aligned opposed central
sections of said front and rear walls, said front and rear walls
having opposed end sections inwardly of the respective central
sections and defining, relative to the space between the central
sections, a reduced spacing between aligned and opposed respective
end sections of said front and rear walls for close accommodation
of said front and rear walls to a received foodstuff, said tray
further including opposed laterally spaced side walls folded upward
respectively from said opposed side edges of said tray bottom, the
laterally spaced relation between said side walls being at a
maximum at opposed central sections of said side walls, said side
walls each having opposed end sections inward of the respective
central sections and defining a reduced spacing at opposed
respective end sections of said side walls for close accommodation
of the side walls to a received foodstuff, said side walls at
opposed ends thereof, joining to and forming corners with
corresponding ends of said front and rear walls to define corners
inwardly offset relative to said maximum spaced central sections
and restricted corner air spaces within said tray for minimizing
heat loss from a received heated foodstuff.
2. The clamshell carton of claim 1 wherein said tray walls each
follow a constant arc along the corresponding edge of the tray
bottom.
3. The clamshell container of claim 2 wherein said front, rear and
side walls have upper edges and incline outward from said bottom to
said upper edges.
4. The clamshell container of claim 3 wherein the edges of the tray
bottom are defined by convex fold lines about which the walls fold
upwardly and which define the arcs of the walls.
5. The clamshell container of claim 4 wherein said front and side
walls maintain said constant arc from said tray bottom to the upper
edges thereof, the arc of said rear wall at the corresponding edge
of the tray bottom progressively decreasing upward from said tray
bottom to the upper edge of said rear wall.
6. The clamshell container of claim 5 wherein said container cover
includes a cover top defined by laterally spaced opposed side edges
and laterally spaced opposed front and rear edges, opposed
laterally spaced cover side walls folded from said top side edges,
and opposed laterally spaced front and rear cover walls folded from
said front and rear edges of said cover top, said front edge and
said side edges of said cover top each being defined by a convex
fold line about which the corresponding walls fold, said cover side
and front walls being convex relative to said cover top with the
arc of each of these walls being defined by the corresponding fold
line between the wall and the top.
7. The clamshell container of claim 6 wherein said rear edge of
said cover top is defined by a straight fold line, said cover rear
wall being planar.
8. The clamshell container of claim 7 wherein said tray rear wall
and said cover rear wall have common outer edges joined along a
straight fold line providing hinge means between said cover and
said tray for a selective closing of said cover over said tray.
9. The clamshell container of claim 8 wherein, upon a closing of
said cover over said tray, said cover side and front walls overlie
said tray side and front walls in intimate contact with the upper
edges of said tray side and front walls, said cover front wall
being of a substantially greater height than said tray front
wall.
10. A clamshell container formed of foldable paperboard and
comprising a tray and a cover, said tray comprising a bottom panel
with opposed side edges and opposed front and rear edges, a pair of
transversely spaced side walls integral with and folded from said
opposed side edges of said bottom panel along convex side fold
lines, each side fold line defining an arcuate configuration to the
corresponding side wall above said bottom panel, said tray further
including transversely spaced front and rear walls respectively
integral with and folded from the opposed front and rear edges of
said bottom panel along a convex front fold line and a convex rear
fold line, said front and rear fold lines defining an arcuate
configuration to each of said front and rear walls above said
bottom panel, said cover comprising a top panel, said top panel
having opposed side edges and opposed front and rear edges, a pair
of opposed transversely spaced cover side walls and a cover front
wall integral with and folded from corresponding side and front
edges of said top panel along fold lines convex relative to said
top panel, and a cover rear wall opposed to and transversely spaced
from said cover front wall, said cover rear wall being integral
with and folded from a linear fold line defining said rear edge of
said top panel, said tray rear wall and said cover rear wall having
a common outer edge defined by a linear fold line forming a hinge
joinder between said tray and said cover for selective closing of
said cover over said tray.
11. The clamshell container of claim 10 wherein the transverse
spacing between the walls of each pair of opposed walls of both the
tray and the cover is at a maximum at the central point of each
wall with this transverse spacing decreasing between each pair of
opposed walls toward opposite ends of the walls of each pair of
opposed walls, whereby the transverse spacing between corresponding
ends of each pair of opposed walls is less than the transverse
spacing between the corresponding center points of the same pair of
opposed walls.
12. The clamshell container of claim 11 wherein the ends of each
tray wall are joined to adjacent ends of adjoining walls to form
four corners about said tray bottom, each corner defining an
included angle of greater than 90.degree..
13. A container blank foldable to define a tray and cover, said
blank including a tray section and an aligned cover section, said
tray section having a central bottom panel defined by a pair of
opposed convex side wall fold lines, a convex front wall fold line
and an opposed convex rear wall fold line, a pair of opposed side
wall panels integral with said bottom panel and foldable relative
thereto along said side wall fold lines, a front wall panel and a
rear wall panel integral with said bottom panel and foldable
relative thereto respectively along said front and rear wall fold
lines, each convex wall fold line being at a transverse spacing
from the opposed fold line which is at a maximum at transversely
aligned center points of the opposed fold lines and which
progressively decrease outward from the central points to a minimum
spacing at transversely aligned ends of the opposed fold lines.
14. The blank of claim 13 wherein said cover section has a central
top panel defined by a pair of opposed convex side wall fold lines,
a front wall fold line and an opposed rear wall fold line, a pair
of opposed cover side wall panels integral with said top panel and
foldable relative thereto along said top panel side wall fold
lines, a cover front wall panel and a cover rear wall panel
integral with said top panel and foldable relative thereto
respectively along the front and rear top panel fold lines.
15. The blank of claim 14 wherein said top panel front wall fold
line is convex.
16. The blank of claim 15 wherein said cover rear wall fold line is
linear, each cover convex wall fold line being at a transverse
spacing from the opposed fold line which is at a maximum at
transversely aligned center points of the opposed fold lines and
which progressively decrease outward from the center points to a
minimum spacing at transversely aligned ends of the opposed fold
lines.
17. The blank of claim 16 wherein said rear wall panels of said
tray section and said cover section have a common linear outer edge
defined by a hinge-forming linear fold line.
18. The blank of claim 17 wherein said tray front wall panel has a
concave arc outer edge, said cover front wall panel having a convex
arc outer edge complementing the concave arc of the tray front wall
panel outer edge.
19. The blank of claim 18 wherein the cover front wall is of a
transverse width greater than that of the tray front wall panel to
define an enhanced display surface in a folded container.
20. The blank of claim 19 wherein said tray side wall panels have
arced outer edges, said cover side walls panels having arced outer
edges complementing the arcs in the outer edges of the tray side
wall panels for a simultaneous defining of these outer edges
between duplicate blanks when simultaneously cutting multiple
blanks.
Description
CLAIM OF PRIORITY UNDER 35 U.S.C. .sctn.119(e)
[0001] Applicant claims the benefit of priority of Provisional
Patent Application No. 60/857,801, filed on Nov. 9, 2006.
BACKGROUND OF THE INVENTION
[0002] Clamshell containers of paperboard and like sheet materials
have long been known and used as takeout cartons for foodstuffs,
particularly although not exclusively in fast food establishments.
As will be recognized, such containers are, for the most part, of a
square configuration intended to generally conform to and
principally package hamburgers and other foodstuffs of similar
shapes.
[0003] Because of the planar nature of the paperboard panels which
fold from a blank to define the container, and as the typical
hamburger is round, the conventional clamshell container includes
rather large defined interior air spaces about a received
hamburger, particularly at the corners of the container. Such air
spaces have been found to be a substantial source of heat loss from
any warmed or heated foodstuff. Likewise, the lack of an effective
seal between the lid and tray of the conventional paperboard
clamshell container can also be a potential source of substantial
heat loss. However, little attention has heretofore been directed
to addressing the heat loss problem in such containers.
[0004] Another factor to be considered in the formation of
paperboard containers is the amount of paperboard material used.
Basically, as a container for foods, the paperboard itself must be
of high quality and be food compatible leak proof to a degree,
structurally stable, etc. Such material is quite expensive. Thus,
any reduction in the blank material required to form the container
is highly desirable. As a practical matter, such blanks are
normally cut in groups by a single impression or "hit" of the die.
In view of the huge numbers of such disposable cartons utilized
each year, in the hundreds of millions, any reduction in material,
scrap or waste in the forming of the blanks can result in
substantial savings and significant economical and ecological
advantages.
SUMMARY OF THE INVENTION
[0005] The present invention, in an acknowledged extremely crowded
art, has several important objects which are considered to advance
the art in a patentably significant manner.
[0006] Two principal and interrelated objects involve an
economically significant reduction in the material used in the
formation of the container, and the formation of a container with
enhanced heat retention capabilities.
[0007] In achieving the above objects, it is also an intention of
the present invention to provide a container which presents an
attractive contemporary appearance with contoured lines and, as
desired, an enhanced surface display area.
[0008] Inasmuch as a substantial loss of heat from a received
product results from the rather large corner air spaces provided in
the conventional or traditional clamshell container, the present
invention specifically provides for the reduction of these air
spaces by utilizing concave walls as opposed to the more
conventional planar or flat walls. Basically, both the tray walls
and at least the majority of the lid or cover walls are concavely
arced from about the tray bottom and cover top to define an area
generally corresponding to that of a circular hamburger bun.
[0009] The opposed ends of each tray wall panel arc inwardly and
are joined, at corners, appreciably inwardly spaced from a similar
corner-forming joinder were the walls panels joined at right angles
as in the conventional planar configuration of a traditional
clamshell. As an example, in comparison to a conventional container
tray of approximately four inches by four inches, an arc from the
central section of each wall to each end thereof sufficient to
inwardly offset the corner forming end portions 1/8 inch will
reduce the length of the side edge of the formed tray a total of
1/4 inch. As compared to the traditional clamshell, this in turn
will reduce each corner air space, on a radial line bisecting the
formed corner, approximately 25%. The reduction in the corner air
spaces, while in no way affecting the reception of the hamburger or
like foodstuff within the container, will inherently enhance the
heat retention capability of the closed container. With similar
structural enhancements of the cover of the tray, the length of the
opposed sides of each clamshell forming blank can be reduced as
much as 1/2 inch. Such a savings in material, when producing
literally millions of such blanks and containers, as noted above,
is of tremendous significance both ecologically and economically,
particularly when considering the single use disposable nature of
the clamshell containers. Thus, it will be recognized that the two
principal objects of the invention are achieved, that of
substantially reducing the space within the container and the heat
loss arising therefrom, and a significant reduction in the material
required in the formation of the blank and container, all without
affecting the basic function of the clamshell as a means for
retaining a common foodstuff.
[0010] As will be recognized as the invention is further explained
and illustrated, in bringing together the ends of adjoining wall
portions to define the reduced air spaces, corner angles of
slightly greater than 90.degree. are formed. This will allow minor
although significant modifications in the joined ends of the walls
which will provide for elimination of additional paperboard
material for further savings.
[0011] The various objects and advantages residing in the present
invention will be better appreciated from the following more
detailed description and drawings presented for illustration of the
invention.
BRIEF DESCRIPTION OF THE DRAWINGS
[0012] FIG. 1A is a cross-sectional view of a typical prior art
clamshell container with a hamburger sandwich illustrated in
phantom lines therein;
[0013] FIG. 1B is a similar cross-sectional view taken through the
clamshell container of the present invention and illustrating the
inwardly shifted corners providing the reduced internal air spaces
and enhanced sealing between the tray and lid walls;
[0014] FIG. 2A illustrates the prior art blank from which the
traditional container of FIG. 1A is folded;
[0015] FIG. 2B illustrates the improved blank of the present
invention from which the container of FIG. 1B is folded;
[0016] FIG. 3 is an enlarged detail view of a typical tray corner
area as indicated on FIG. 2B superimposed on a phantom line showing
of the corresponding corner area of the prior art container;
[0017] FIG. 4 illustrates a nested layout allowed by the blank of
the present invention for the simultaneous formation of multiple
blanks with a single die impression;
[0018] FIG. 5 is a perspective view of the clamshell container of
the invention with the lid or cover open; and
[0019] FIG. 6 is a perspective view of the closed clamshell
container with the rather taller cover front wall presenting a
significant display panel.
DESCRIPTION OF PREFERRED EMBODIMENT
[0020] Referring now more specifically to the drawings, FIGS. 1A
and 2A illustrate the traditional prior art clamshell container
includes a tray 10 and a lid or cover 12 integrally joined and
folded from a single blank 14. The tray 10, referring both to the
folded container and the blank 14, includes a flat rectangular
bottom or bottom panel 16 sized to, in the preferred embodiment,
receive a hamburger sandwich as suggested in the phantom line
showings. Opposed planar tray side panels 18 are integral with
opposed side edges of the bottom panel 16 along linear fold lines.
Similarly, opposed planar front and rear tray wall panels 20 and 22
are integral with the front and rear edges of the tray bottom along
linear fold lines.
[0021] The cover 12 is similarly formed with a rectangular top or
top panel 24, opposed side walls 26 integral with opposed side
edges of the top panel 24 along linear fold lines, and opposed
planar front and rear cover walls 28 and 30 also integral with the
top panel and foldable relative thereto along linear fold lines.
The rear walls 22 and 30 of the tray and cover are integrally
joined along a linear hinge forming fold line 32 for a selective
opening and closing of the cover. As is traditional, appropriate
glue and latch tabs 34 will be used in assembling the container and
securing the folded tray and container walls at the respective
corners.
[0022] Noting the cross sectional detail of FIG. 1A in particular,
it will be seen that a traditional container formed from flat
panels along straight fold lines, as above described, while capable
of receiving and carrying takeout foods, is not particularly
effective in retaining heat. This is due both to rather large air
spaces 36 provided at the various corner areas of the tray and
cover, and in light of the less than effective sealing of the cover
walls with the tray walls, resulting in spaces or gaps as suggested
at 38.
[0023] Referring now to the present invention, attention is
directed to FIGS. 1B and 2B, and initially to the blank 39
illustrated in FIG. 2B. As with the prior art blank 14, the blank
39 includes both a tray 40 and a cover 42. While the blank 39 also
includes all of the basic components of the prior art blank 14,
including top and bottom panels, peripheral walls, glue flaps, and
the like, significant differences exist with regard to the
structure and relationship of the components to each other.
[0024] More particularly, the opposed side walls 44 of the tray 40
are integral with the opposed side edges of the tray bottom 46
along arcuate fold lines 48 which are convex relative to the tray
bottom 46. The fold lines 48 each include opposed end portions 50
distinctly inwardly offset relative to the central section or
center point 52 of the corresponding fold line 48. It will be
appreciated that the maximum transverse width of the tray bottom 46
will be between the central points 52 of the opposed side walls
fold lines 48. As suggested by the phantom line showing of the
hamburger, this transverse width will be essentially equal to the
transverse width of the prior art carton or container. However, as
will be noted and as is particularly significant, the transverse
width between aligned and opposed end portions 50 of the two fold
lines 48 will be appreciably reduced while at the same time in no
way interfering with the space required for the accommodation of
the hamburger.
[0025] The front and rear walls 52 and 54 of the tray 44 are
similarly foldably joined to the front and rear edges of the tray
bottom 46 along arcuate fold lines 56. The fold lines 56, as with
the fold lines 48, have the opposed and aligned end portions 58
thereof inwardly offset with the transverse distance between the
front and rear fold lines 56 being at a maximum spacing at the
center points and at a minimum spacing at the fold line end
portions 58.
[0026] The adjoining end portions of the fold lines 48 and 56 and
the associated wall panels define the four corners 60 of the tray
40. The corners 60 formed by the joined wall panel ends are
inwardly offset and defining an obtuse angles, that is an angle
greater than 90.degree., as opposed to the right angle corners 62
formed by the joined panel ends of the conventional carton tray 10.
In this regard, note the enlarged detail of FIG. 3 and the overlay
relationship shown therein for purposes of illustration. The space
64 between the fold lines of the conventional tray and the inwardly
offset end portions 50 and 58 of fold lines 48 and 56 represents a
reduction in the material required in the formation of the blank 39
which is substantial. For example, in a container tray of
conventional size, approximately 4 inches by 4 inches, a 1/8 inch
radius arc from the center point of each fold line to each corner,
that is an arc which will inwardly offset each corner of each fold
line 1/8 inch from the center point thereof, will result in a space
saving and reduction of material equal to 1/8 inch for a total of
1/4 inch in the edge dimension of the tray both along the sides and
across the front and rear thereof. In addition to the significant
material reduction, it will also be noted that by in effect
inwardly offsetting the corners, the corner spaces about the
hamburger are also reduced. Using the 1/8 inch reduction noted
above, this space reduction will produce a reduction of
approximately 25% between the new corner position and the received
hamburger. Note the dimension line 66 in FIGS. 2B and 3.
Incidentally, in addition to the savings in material uniquely
produced by the inward offsetting of the corner construction, and
noting the detail of FIG. 3 in particular, additional material
reduction, as suggested at 68, will also occur at the ends of the
wall panels and the interposed glue flaps and latching lugs which
will be defined to accommodate the repositioned corners.
[0027] Referring now more specifically to the container cover 42,
and noting in particular the blank 39, as in the conventional
container, the cover includes a top or top panel 70, opposed side
walls 72, a front wall 74 and a rear wall 76. The cover top 70 has
opposed side edges defined by convex fold lines 78 with end
portions 80 inwardly offset from corresponding center points 82.
The side walls 72 are integral with and fold relative to the top 70
along these fold lines 78. A similar convex fold line 84, with end
portions 86 inwardly offset from corresponding center point 88
define the forward edge of the top 70 for a folding of the cover
front wall 74. The rear wall 76 of the cover is folded relative to
the rear edge of the top 70 along a linear or straight fold line
90. A similar straight fold line 92 is formed between the joined
outer edges of the tray and cover rear walls 54 and 76 to define a
hinge therebetween. The use of such straight fold lines at these
particular fold points is desired to prevent a buckling action as
the clamshell container is closed.
[0028] It is intended that the dimensional reduction in length and
width of the cover 42, and hence the material saving, closely
correspond to that previously described with regard to the tray
portion 40 of the container. As such, and in order to accommodate
the straight rear wall fold line 90, the radii of the side wall and
front wall fold lines 78 and 84, and the inward offset of the end
portions thereof from the corresponding center points may slightly
differ from those of the tray side and rear wall fold lines 48 and
56. Thus, referring to the example of dimensions referred to above,
a similar reduction in the cover edge length of approximately 1/4
inch will result in a total blank edge length reduction of 1/2
inch, a very appreciable savings in material when considering the
millions of such blanks produced yearly. It will also be recognized
that the inward offsetting of the edge portions of the cover fold
lines 78 and 84 will, in the closed container, similarly and
effectively reduce the cold air space at the interior corners of
the closed container.
[0029] As is the case with regard to the tray 40, in the cover 42,
the transverse distances between the two sets of the generally
parallel fold lines is greatest at the center points thereof with
the transverse distances reduced at the aligned corner portions. In
accommodating the straight rear edge fold line 90 of the top 70
while maintaining the desired edge length reductions as previously
noted, this can be achieved by utilizing a shorter radius in
defining the side wall fold lines 78 and a greater radius in
defining the front wall fold line 84 as compared to the radii
utilized for the fold lines 48 and 56 of the tray 40.
[0030] Referring again to the tray portion of the blank in FIG. 2B,
the tray side walls 44 are preferably formed with arced or convex
outer edges and extend, in the closed carton as suggested in FIG.
1B, higher within the corresponding cover side walls 72. The outer
edge of each cover side wall 72 is defined by a complimentary
concave cut reducing the height thereof an amount equal to the
corresponding height increase of the tray side walls, thus not
conflicting with the overall material reduction desired in the
present invention.
[0031] Noting FIG. 4 and the partial layout of multiple blanks for
utilization of a single die cut, it will be appreciated that the
reverse positioning of adjacent blanks and the complementary
configurations of the outer edges of the tray and cover side walls
allow for a single "hit" or die cut, thus simplifying manufacture
and reducing excess or waste material to a minimum.
[0032] A similar complementary configuration will be noted in the
preferred front walls 52 and 74 of the tray and cover wherein the
outer edge of the tray front wall 52 is concave and relatively
shorter than the front wall of a conventional clamshell container.
At the same time, the front wall 74 of the cover is substantially
taller and includes a convex outer edge, the configuration of which
corresponds to that of the concave outer edge of the tray front
wall 52. This also allows for a single die cut between adjacent
blanks in the formation of the blanks.
[0033] The formation of the walls as above described is preferred
and provides particular advantages over the prior art "flat panel"
container. More particularly, the taller front wall 74 of the
cover, as noted particularly in FIG. 6, provides, in conjunction
with the curvature of the wall itself, an enlarged display area for
logos, designs or any appropriate attractive indicia. The extended
height of the cover front wall and the curvature thereof in
conjunction with the curvature of the tray front wall ensures a
positive continuous engagement of the upper edge of the front tray
wall 52 against the inner surface of the elongate overhanging cover
front wall 74. Such a relationship also occurs between the
overlapping side walls of the tray and cover as will be appreciated
from the schematic cross sectional view of FIG. 1B wherein the
convex upper edges of the tray side walls, initially at the highest
center points thereof, engage against the inner surfaces of the
cover side walls with the continuing closing movement of the cover
causing a slight inward flexing of the tray side walls until full
engagement of the tray side wall upper edges with the inner
surfaces of the cover side walls is achieved and the appropriate
latching means engaged. This avoids and eliminates the air gap
normally experienced in flat-wall containers of the conventional
type as illustrated in FIG. 1A. In addition, in utilizing this
relationship, it has been found that the cover 44 will actually
seat lower on the tray, eliminating unnecessary interior air space
and avoiding the undesirable cooling effect thereof.
[0034] It will also be appreciated that the finished container
itself, particularly when closed as illustrated in FIG. 6 presents
an attractive appearance derived from the smoothly curving or
arcing contours as viewed from both the front and sides, providing
a distinctive appearance desirable for product and/or provider
identification.
[0035] The foregoing describes a preferred embodiment of the
invention and is considered illustrative of the principles of the
invention. In the description above, the front wall of the
container is described as being concave and the front wall of the
cover as convex. If desired, and still within the scope of the
invention, these shapes could be reversed or even have a straight
line cut. It is to be understood that as modifications and changes
may occur to those skilled in the art, it is not desired to limit
the invention to the exact construction as shown and described.
Rather, all suitable modifications and equivalents may be resorted
to as falling within the spirit and scope of the invention as set
forth in the appended claims.
* * * * *