Note: Descriptions are shown in the official language in which they were submitted.
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A CONTAINER
FIELD OF THE INVENTION
[0001] The present invention relates generally to containers, and, more
particularly, to containers whose covers align together when stacked in a
first position
and which can be locked together in a second position.
BACKGROUND OF THE INVENTION
[0002] Rigid, thermoplastic food containers are generally known. Users often
accumulate a large number of these containers in different sizes and shapes.
When not
in use, the containers are often stored haphazardly into drawers. In this
case, the
unused containers take up a great deal of room, and finding a matching base
and cover
in a disarranged drawer may be difficult. To avoid this, some users stack the
containers in cabinets. While the bases of the containers usually nest and
therefore
take up less room than in a disorganized drawer, it may still be difficult to
match a
base with a cover. In addition, the covers may not stack and the covers may
tend to
topple down. When the containers are in use to store food, the containers are
often
stacked one on top of another in cabinets or in a refrigerator. These stacks
may be
precarious, and their fall may cause food to spill from the containers. Many
users
would find it desirable if the containers, whether empty or in use, could be
stored in a
manner space efficient, less precarious, and more structurally rigid.
[0003] During large-scale manufacturing, the covers may be transported in bulk
before being separated out for individual packaging. During bulk handling,
manufacturers would find it desirable if the covers would form a stack stable
enough
to resist the vertical and lateral movements caused by forces typically
encountered
during manufacturing operations.
[0004] The present invention has as a general aim to provide containers that
satisfy both users and manufacturers.
SUMMARY OF THE INVENTION
[0005] In view of the foregoing, the present invention provides containers
whose
covers can be stacked together in two different ways. First, the covers can be
stacked
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into an "aligned" stack. The aligned stack provides enough structural rigidity
for bulk
handling during manufacturing. Second, the covers can be stacked into a
"locked"
stack. The locked stack provides even more structural rigidity than does the
aligned
stack and is useful when storing unused covers.
[0006] In some embodiments, the container cover includes a first closure
portion, an
engagement portion, and an alignment portion. The base includes a second
closure
portion. The first closure portion of the cover is sealingly engageable with
the second
closure portion of the base to define a substantially sealed, leak-proof, and
re-sealable
storage area for items such as food. The alignment portion of the cover is
engageable
with the alignment portion of a second cover to form an aligned cover stack.
The
engagement portion of the cover is engageable with the engagement portion of a
second cover to form a locked cover stack.
[0007] The covers and bases can be economically constructed from relatively
thin-gauge plastic so that the user can either wash them after use or dispose
of them
with the view that their purchase price allows them to be used as a consumable
good.
The container can be readily manufactured, for example, with conventional
thermoforming equipment. The cover can be made from a semi-transparent
material
to ensure satisfactory visibility of the container's contents. The container
can be
suitable for refrigerator, freezer, microwave, and machine dishwasher use.
[0008] The features of the present invention will become apparent to one of
ordinary skill in the art upon reading the detailed description, in
conjunction with the
accompanying drawings, provided herein.
BRIEF DESCRIPTION OF THE DRAWINGS
[0009] Figure 1 is an isometric view of a container with a cover and a base
according to an embodiment of the present invention;
[0010] Figure 2 is an isometric view of the container cover of Figure 1;
[0011] Figure 3 is a top plan view of the container cover of Figure 1;
[0012] Figure 4 is an isometric view of the container base of Figure 1;
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[0013] Figure 5 is a top plan view of the container base of Figure 1;
[0014] Figure 6 is a side sectional view of the container of Figure 1;
[0015] Figure 7 is an enlarged, detail view of a portion of Figure 6;
[0016] Figure 8 is side sectional view of another embodiment of the container
shown in Figure 7;
[0017] Figure 9 is a side sectional view of another embodiment of the
container
shown in Figure 7;
[0018] Figure 10 is a side sectional view of a stack of two sealed containers;
[0019] Figure 11 is a side sectional view of a stack of two nested container
bases
with two locked container covers;
[0020] Figure 12 is a side sectional view of another embodiment of the stack
of
Figure 11;
[0021] Figure 13 is a side sectional view of a stack of two nested container
bases
with one locked container cover and with one aligned cover;
[0022] Figure 14 is a side sectional view of another embodiment of the stack
of
Figure 13;
[0023] Figure 15 is a side sectional view of an aligned stack of a container
cover
and a base;
[0024] Figure 16 is a side sectional view of a stack of two nested container
bases
with two aligned container covers;
[0025] Figure 17 is a side sectional view of a stack of two nested container
bases
with one aligned container cover and with one locked container cover;
[0026] Figure 18 is a side sectional view of a locked stack of two container
covers;
[0027] Figure 19 is an enlarged, detail view of a portion of Figure 18;
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[0028] Figure 20 is a side sectional view of an aligned stack of two container
covers;
[0029] Figure 21 is an enlarged, detail view of a portion of Figure 20;
[0030] Figure 22 is a process flow diagram of an exemplary manufacturing
process for making containers according to the present invention; and
[0031] Figure 23 is a process flow diagram of another exemplary manufacturing
process for making containers according to the present invention.
DETAILED DESCRIPTION OF THE INVENTION
[0032] Turning to the drawings, wherein like reference numerals refer to like
elements, a first embodiment of the present invention is illustrated in
Figures 1
through 5. A container 100 includes a flexible cover 102 sealingly engaged to
a base
104. In the example of Figures 1 through 5, the container 100 is depicted as
substantially square with rounded corners. In other embodiments of the present
invention, the container 100 has other shapes such as rectangular, circular,
or elliptical.
[0033] The container cover 102 can include at least one gripping tab 106 to
facilitate removal of the cover 102 from the container base 104. In some
embodiments,
the gripping tab 106 includes one or more cross-ribs or a textured surface to
improve
a user's grip on the tab 106.
[0034] The container cover 102 illustrated in Figures 2 and 3 includes an
engagement portion 200 that allows the cover 102 to engage with the engagement
portion 200 of a second cover 102 to form a locked stack of covers 102. This
locking
feature makes the resultant stack of covers more structurally rigid and thus
less
precarious than a traditional, non-interlocked, stack of covers.
[0035] The engagement portion 200 of Figures 2 and 3 is depicted as circular
but,
as with the shape of the container 100 itself, other shapes are possible. In
some
embodiments, a standard shape and configuration of the engagement portion 200
is
used with covers 102 of various shapes and sizes. This enhances storage
flexibility by
allowing different types of covers 102 to be stored together in a locked
stack. The
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engagement portion 200 can also be chosen to have a shape or otherwise include
elements that provide an aligned or locked stack of covers 102 with rotational
alignment where rotation is defined about an axis normal to the point 302 at
which
midlines 304 and 306 of the cover 102 intersect as shown in Figure 3. For
instance,
shapes that inherently require alignment prior to engagement or that may be
self-
aligning during the process of connecting engagement portions would be shapes
with
linear or curvilinear sides, vertices or lobes such as triangular, square,
rectangular, or
multi-petal shapes. Additionally, the cover may have one or more elements on
or
about the engagement portion that require alignment prior to connection of
engagement portions or elements that may be self-aligning during the process
of
connecting engagement portions.
[0036] The container cover 102 may have a central field 300, shown in Figure 3
on the top of the engagement portion 200. The central field 300 may include an
embossed symbol such as a manufacturer's mark or may allow a user to attach a
label
or to write information, such as the date or user's name. When the central
field 300
includes a writeable area, that area could be of an opaque color which would
receive a
contrasting color from a writing instrument. The writeable area could be
incorporated
into the material for the container cover 102 or could be applied to that
material by
printing.
[0037] The container cover 102 of Figures 1 through 3 can be constructed with
a
wall thickness thinner than that of a container base 104. The cover 102 can be
made
from any suitable plastic and can be made by any suitable technique, such as
thermoforming. In one embodiment, the cover 102 can be formed from
polypropylene.
Due to the thermoforming process, the wall thiclrness of the cover 102 can
vary. A
thinner container cover 102 reduces material costs and increases flexibility
to more
easily accommodate its removal from, and engagement with, a container base
104.
The cover 102 can maintain adequate flexibility for proper sealing even during
typical
freezer temperatures.
[0038] The container base 104 of Figures 4 and 5 includes a bottom 400 and a
sidewall 402 extending from the periphery of the bottom 400. The bottom 400
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includes a raised lower section 404 to accommodate the engagement portion 200
of a
container cover 102 when containers 100 are stacked together. This feature is
further
discussed and illustrated below. Just as the engagement portion 200 of Figure
3 can
include a central field 300, a similar field for a manufacturer's mark or for
user
information could be included in the raised portion 404 of the base 104.
[0039] The container base 104 of Figures 1, 4, and 5 can be made from any
suitable plastic with sufficient thickness to withstand without deforming the
heat of
microwave cooking and of top-shelf dishwashing. It should also remain sturdy
during
lifting while laden with hot food. The base 104 can be made from any suitable
plastic
and can be made by any suitable technique, such as co-extrusion, lamination,
injection
molding, thermoforming, or overmolding. In one embodiment, the container base
104
is formed from polypropylene. The wall thickness of the container base 104 can
vary
due to the manufacturing process.
[0040] Figures 6 through 9 present embodiments of a container 100 whose cover
102 is sealingly engaged with its base 104. Figure 6 shows the cover 102
cooperating
with the base 104 to define a sealed storage compartment 600. The cover 102
can be
sufficiently flexible to allow a user to create a vacuum in the container 100
upon
sealing. In order to create a vacuum, the user could, for example, depress the
cover
102 during the closing of the container 100. A return force imparted upon the
cover
102 by the resiliency of the material of the cover 102 will urge the cover 102
to return
to its normal position, thereby creating a vacuum. To facilitate convenient
sealing
engagement of the cover 102 with its base 104, the users can, at their
discretion, apply
downward force to only the engagement portion 200 of the container cover 102.
The
engagement portion 200 is located to accept and distribute the force to the
first closure
portion 700 of the cover 102 during sealing to the base 104. The engagement
portion
200 may also act as a convenient handle for grasping the cover 102.
[0041] In the embodiments of Figures 6 through 9, the container 100 uses a
locking rim design that includes both inside and outside seals as will be
described.
The present invention can be embodied with a variety of closure designs
including
outer closures and/or inner closures.
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[0042] Figure 7 depicts an embodiment of the closure portions used to engage
the
cover 102 with the base 104 of the container 100. The cover 102 includes a
first
closure portion 700 in the form of a raised locking ring. The first closure
portion 700
of the cover 102 can be engaged with a second closure portion 702 of the base
104 to
provide a leak-resistant, re-sealable closure.
[0043] The first closure portion 700 includes an inner wall 704, a retention
bead
706, and an outer wall 708. The inner wa11704, the retention bead 706, and the
outer
wa11708 defme a first sealing surface, which is part of the lower surface of
the cover
102. The first closure portion 700 can include one or more locking ridges 710.
The
outer wall 708 extends between the retention bead 706 and a flange 712. The
flange
712 can provide a convenient gripping surface to facilitate the removal of the
cover
102 from the base 104.
[0044] As illustrated in Figure 7, the second closure portion 702 of the base
104 is
a raised locking ring that extends from an upper edge of the sidewall of the
base 104.
The second closure portion 702 includes an inner wall 714, a retention bead
716, and
an outer wal1718. The inner wal1714, the retention bead 716, and the outer
wall 718
define a second sealing surface, which is part of the upper surface of the
base 104.
The second closure portion 702 can include one or more locking ridges 720. The
outer
wal1718 extends between the retention bead 716 and a flange 722. The flange
722 can
provide a convenient gripping surface to facilitate the removal of the cover
102 from
the base 104.
[0045] The first and second closure portions 700 and 702 can be configured to
be
slightly different in size to form an interference fit therebetween. The
interference fit
between the first and second closure portions 700 and 702 can provide a
sealing
engagement between the closure portions. As a result, when the two pieces are
engaged, a positive seal can be formed between the first and second sealing
surfaces
around the perimeters of the base 104 and of the cover 102.
[0046] The engagement of the first and second closure portions 700 and 702 can
be accompanied by an audible "snap" indicating that the container is securely
closed.
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[0047] In the example of Figure 7, the inner wall 704 of the first closure
portion
700 of the cover 102 extends to the engagement portion 200. This engagement
portion
200 includes an upper protrusion 724 and a lower protrusion 726.
[0048] In the embodiment of Figure 7, the cover 102 includes a ridge 728 on
the
outer wall 708 of the first closure portion 700. Figure 8 presents another
embodiment
without this ridge. In general, the first and second closure portions 700 and
702 and
the engagement portion 200 shown in Figures 6 through 9 are examples only, and
many other types of closure and engagement portions could be used with the
present
invention. For example, the engagement portion 200 could include complementary
locking rings. As these and many other types of closure and engagement
portions are
well known in the art, they need not be discussed at length here.
[0049] Figure 9 shows another embodiment of the cover. The cover 102 of Figure
9 includes an alignment ridge 900 located on the outer wall 708 of the first
closure
portion 700. This alignment ridge 900 is discussed in detail below.
[0050] In Figure 10, the sealed container 100 rests on top of a second sealed
container 1000. The raised lower section 404 of the base 104 of the upper
container
100 accommodates the engagement portion 200 of the cover 1002 of the lower
container 1000.
[0051] Figures 11 and 12 show the utility of an embodiment of the invention
when the containers are in storage. In the Figures, a stack of two nested
container
bases 104 and 1100 is joined to a locked stack of covers 102 and 1102. The
lower
cover 102 is sealingly engaged with the upper base 104 to form a structurally
rigid
stack.
[0052] In the embodiment of Figures 11 and 12, the two covers 102 and 1102 are
locked together by their engagement portions 200. As described in relation to
Figure 7,
the engagement portions 200 can each include an upper protrusion 724 and a
lower
protrusion 726. Each protrusion 724, 726 is convex on one side and concave on
the
other. The lower protrusion 726 of the upper cover 1102 fits over and receives
the
upper protrusion 724 of the lower cover 102, thus locking the covers 102 and
1102
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together. In this manner, the covers 102 and 1102 are held together and form a
structurally stable cover stack. Other embodiments of the engagement portion
may
include one or more of the following features to enable engagement: convex
portions
or ribs, concave portions or ribs, linear or curvilinear undercuts, discrete
snap
elements or buttons, interference fits, textured surfaces, or elements that
modify
surface friction or tackiness at or around the point of engagement. The
engaging areas
that create a locking condition can be continuous about the engagement portion
or
discretely segmented about the engagement portion. In some embodiments, the
force
required to connect the covers may differ substantially from the force
required to
disengage the covers. For instance, it may be beneficial during manufacturing
that the
force needed to connect the covers is less than the force required to separate
the
covers. As a result, the covers are relatively easy to connect during
manufacturing, yet
they will lock securely and not undesirably separate during the manufacturing
process.
To accomplish this, the protrusions on the engagement portion may be designed
where, for a given protrusion, the upper protrusion edge comprises a gradual
taper
whereas the lower protrusion edge comprises a more abrupt shape. For example,
in
one embodiment, the shape of the protrusion may be similar to a barbed hook
with
gradual taper on the upper edge of the barb that would impart little
resistance during
engagement and with an abrupt shape on the lower edge of the barb that would
impart
relatively high resistance during disengagement. Conversely, it may be
beneficial to
design the engagement portion so that the force that needs to be applied to
connect the
covers is more than the force required to separate the covers, since the user
may
perceive that a high connecting force equates to satisfactory locking
integrity, whereas
a weak connecting force may lead the user to perceive that the cover stack
lacks the
integrity required to insure the expected organizational benefit. Thus the
high
connecting force provides the perceived benefit, yet a lower disengagement
force does
not require that the user untowardly struggle during separation of covers. To
accomplish this, the protrusions on the engagement portion may be designed
where,
for a given protrusion, the upper protrusion edge comprises an abrupt shape
whereas
the lower protrusion edge comprises a more gradual taper. For example, in one
embodiment, the shape of the protrusion may be a reversed barb with an abrupt
shape
on the upper edge of the barb that would impart relatively high resistance
during
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engagement and with a gradual taper on the lower edge of the barb that would
impart
little resistance during disengagement. Furthermore, during the process where
the
user applies force to aligned covers in a direction normal to the general
cover plane so
as to lock the covers together, the engagement portion can provide tactile or
audible
feedback upon locking. In this way the user would sense that the covers are
connected
and that no further force need be applied.
[0053] The container bases 104 and 1100 are shown nested in Figures 11 and 12
but are not locked together. In many applications, nesting the container bases
without
locking them together provides sufficient structural rigidity to a stack of
bases. It is
possible, however, to apply the techniques of the present invention to the
bases
themselves and to thus provide a mechanism for locking the bases together. The
same
types of closure and engagement portions available for locking the covers
together or
for locking the covers to the bases can be adapted to locking the bases
together.
[0054] The container covers 102 and 1102 of Figure 11 include the ridge 728
described in relation to Figure 7, while the covers in Figure 12 do not
include this
feature. The ridge 728 provides a rigidifying function to the outer wall 708
and also
provides a retaining ledge to assist de-nesting of covers during manufacture.
[0055] Figures 13 and 14 present another position for the stack of covers in
Figures 11 and 12. The container bases 104 and 1100 are nested together and
the
lower cover 102 is locked onto the upper base 104. However, the upper cover
1102 is
not locked to the lower cover 102. Instead, the upper cover 1102 is resting
on, and
aligned with, the lower cover 102. In this configuration, the two covers 102
and 1102
are said to form an "aligned" stack to distinguish it from the locked stack of
Figures
11 and 12. The ability to form an aligned, but not locked, stack is important
in
manufacturing because it allows the covers to be transported in bulk before
being
separated out for individual packaging. The aligned stack is stable enough to
resist the
vertical, lateral, or rotational movements caused by forces typically
encountered
during manufacturing operations, but the covers are not so strongly connected
that
they hinder de-nesting when necessary.
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[0056] The tab 106 (see Figure 1) can be designed so that the tabs nest in an
interdigitating fashion when in a stack of covers so that the covers are kept
in an
aligned configuration. In one embodiment, the design of the tab 106 permits
stable
cover-to-cover stacking in the immediate vicinity of the tab 106 in the locked
state,
such that a portion of the tab 106 comes to rest on a portion of the cover
below it in
the stack to provide resistance to further stack compression.
[0057] In the embodiment of Figure 13, the covers 102 and 1102 align by
touching in two areas. First, the engagement portions 200 of the covers 102
and 1102
each includes a lower shoulder 1300 and an upper shoulder 1302. The lower
shoulder
1300 of the upper cover 1102 rests on the upper shoulder 1302 of the lower
cover 102.
Second, the flange 712 of the upper cover 1102 rests on the outer wall 708 of
the
lower cover 102. These two contact areas serve to align the covers 102 and
1102 into
a stack less structurally rigid than a locked stack, but sufficiently rigid
for many
purposes. Comparing Figures 11 and 13 shows how an aligned stack can be
converted
into a locked and rotationally aligned stack by an application of pressure
upon the
stacked items. Figure 11 shows that when force is applied to the aligned stack
of
Figure 13 to create a locked stack, the flange 712 of the upper cover 1102 is
pushed
farther down the outer wall 708 of the lower cover 102. Cover alignxnent is
further
rigidified by the touching of covers 102 and 1102 at the inside wall of the
closure
portions. In the embodiment of Figure 11, the cover inner wall 704 includes an
upper
shoulder 1104 located just above the uppermost locking ridge 710 and a lower
shoulder 1106 located just below the lowermost locking ridge 710. Thus, in
this pair
of locked covers, the lower shoulder 1106 of the cover 1102 rests on the upper
shoulder 1104 of the cover 102. Considering both Figures 11 and 13, the flange
712
that creates an aligned condition can be continuous along the perimetric path
of the
first closure portion 700 or discreetly segmented along the perimetric path of
the first
closure portion 700. Considering Figure 12, the contacting shoulders 1104 and
1106
of the inside wall 704 that create an aligned condition between locked covers
can be
continuous along the perimetric path of the first closure portion 700 or
discreetly
segmented along the perimetric path of the first closure portion 700. In some
embodiments, this alignment feature may be desirable to ensure that the
connected
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covers are aligned rotationally about an axis normal to the center of the
covers,
especially when the covers include engagement portions that permit rotation
between
the covers. In some embodiments, if the alignment feature were absent, then
the
covers would be free to rotate. Free rotation could have undesirable
consequences
because the cover stack may be inadequately organized to facilitate
manufacturing or
may inadequately provide an organizational benefit to the user.
[0058] The embodiment of Figure 14 differs from that of Figure 13 in that the
flange 712 of the upper cover 1102 does not come down far enough to touch the
lower
cover 102 when the covers 102 and 1102 are in an aligned stack. Variations
such as
those between the embodiments of Figures 13 and 14 can be chosen to alter the
amount of rigidity present in an aligned stack. Even though the flange 712 of
the
upper cover 1102 does not come down far enough to touch the lower cover 102 in
this
less rigid aligned stack, the contact between the lower shoulder 1300 of the
engagement portion 200 of the upper cover 1102 and the upper shoulder 1302 of
the
lower cover 102 can provide concentric or rotational aligmnent to assist the
user in
aligning the engagement portions 200 during the process of connecting covers.
Comparing Figures 12 and 14 shows how an aligned stack can be converted into a
locked and rotationally aligned stack by an application of pressure upon the
stacked
items. Figure 12 shows that when force is applied to the aligned stack of
Figure 14 to
create a locked stack, the cover alignment is fiu-ther rigidified by the
touching of
covers 102 and 1102 in two areas. First, the flange 712 of the upper cover
1102 rests
on the outer wall 708 of the lower cover 102. Second, the lower shoulder 1106
of the
upper cover 1102 rests on the upper shoulder 1104 of the lower cover 102. In
some
embodiments, this alignment feature may be desirable to ensure that the
connected
covers are aligned rotationally about an axis normal to the center of the
covers,
especially when the covers may include engagement portions that permit
rotation
between the covers. _
[0059] Figure 15 shows that a container cover 102 can be aligned, without
locking,
onto the top of a container base 104. Figure 16 shows an aligned stack of two
covers
102 and 1102 on top of a nested stack of bases 104 and 1100. Figure 17 differs
from
Figure 16 in that the upper cover 1102 is locked onto the lower cover 102.
Comparing
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Figures 16 and 17 shows how an aligned stack can be converted into a locked
stack by
an application of pressure upon the stacked items.
[0060] Figure 16 also shows another embodiment of the alignment portion of the
container covers 102 and 1102. An alignment ridge 900 is located on the outer
wall
708 of the covers 102 and 1102. When in an aligned stack, the flange 712 of
the upper
cover 1102 rests on the alignment ridge 900 of the lower cover 102 increasing
the
rigidity of the stack. Figure 17 shows that when pressure is applied to the
aligned
stack to create a locked stack, the flange 712 of the upper cover 1102 is
pushed past
the alignment ridge 900 of the lower cover 102.
[0061] Figures 18 and 19 emphasize the compactness of a locked stack of
container covers 102 and 1102, while Figures 20 and 21 emphasize the
compactness
of an aligned stack of container covers. While the aligned stack is not quite
as
compact as the locked stack, the compactness of either stack is a significant
benefit of
the present invention when covers are stored for future use.
[0062] A high-level abstraction of an exemplary manufacturing process usable
for
making containers according to the present invention is shown in Figure 22.
Extruded
sheets of plastic (step 2200) are thennoformed into rough bases (step 2202).
The extra
plastic is trimmed from the rough bases (step 2204), and the completed bases
are then
nested into a stack (step 2206) for further handling.
[0063] In parallel with the above steps, covers are made in a similar process
(steps
2212 through 2218). In steps 2216 and 2218, the completed covers need not be
locked
together because an aligned cover stack is sufficiently rigid for bulk
handing.
[0064] For packaging the completed bases and covers, an appropriate number of
bases (steps 2208 and 2210) and covers (steps 2220 and 2222) are removed from
their
respective stacks. The bases and covers are stacked and combined with
packaging
materials (steps 2224 through 2228) to create an individual retail unit 2230
(which
may include a number of bases and covers). The individual retail units are
then
packed together in bulk (step 2232) for shipment to retail outlets.
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[0065] Figure 23 presents a variation on the manufacturing process of Figure
22.
In the embodiment of Figure 23, the bases are processed through the same steps
2200
through 2210. However, in step 2316 of Figure 23, the covers are locked
together in a
stack rather than forming the aligned stack of Figure 22's step 2216. In some
manufacturing environments, increased structural rigidity makes the locked
cover
stack more appropriate than the aligned cover stack. The locked stack of
covers is
processed through steps 2318, 2220, and 2322. In step 2224 of Figure 23, an
appropriate number of locked covers are combined with bases and packaging
materials to create an individual retail unit 2330.
[0066] The container can be reusable, but it can also be constructed cheaply
enough that consumers see it as a disposable item, with replacement covers and
bases
available separately for retail sale. The base and the cover can be fabricated
by
thermoforming a clarified polypropylene homopolymer material. In another
embodiment, the container may be fabricated by thermoforming a clarified
random
copolymer polypropylene material. Other plastic materials which would be
suitable
for fabricating the container by thermoforming include PS (polystyrene), CPET
(crystalline polyethylene terephthalate), APET (amorphous polyethylene
terephthalate), HDPE (high density polyethylene), PVC (polyvinyl chloride), PC
(polycarbonate), and foanied polypropylene. The material used can be generally
transparent to allow a user to view the contents of the container.
[0067] The container may include a visual indication of closure between the
container cover and the container base. The visual indication may be a color
change in
the area where the cover engages the base. In one embodiment, the closure
portion on
the cover may be a first color and the closure portion on the base may be a
second
color. When the closure portions are engaged, the first and second colors
produce a
third color which is visible to the user to indicate that the container is
sealed.
[0068] The container may include a rough exterior surface to reduce slipping
and
to improve grasping by the user, especially if the user's hands are wet or
greasy.
[0069] The container may include a self-venting feature. The pressure in the
sealed container may increase when the sealed container and contents are
heated in a
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microwave oven. Thus, the container cover may include a self-venting mechanism
which opens when the pressure in the container exceeds a predetermined value.
[0070] The container may be divided to separate foods in the container. A
divider
may be integral with the container or may be a separate component. Either the
base
only may include a divider or both the base and the cover may each include a
divider.
The divider located in the cover may only partially engage the divider in the
base so
as to provide splash protection, or it may fully engage the divider in the
base to
provide varying degrees of inter-compartmental leak resistance.
[0071] The container may include a strip indicating the temperature of the
container and its contents.
[0072] The gripping tab can include a relieved portion that provides less
interference contact with the base during the removal or engagement of the
cover
while still providing an adequate closure portion to maintain proper sealing
of the
container. The relieved portions of the gripping tab permit venting by
allowing a
portion of the cover to be unsealed from the base while still maintaining a
seal around
the remaining perimeter of the container. This feature is useful in microwave
cooking
where the cover prevents food from splattering onto the inside surface of the
microwave while still allowing the container to vent. By using the gripping
tab, less
force is required to remove the cover from the base. This lower opening force
also
reduces the possibility of container failure from stress and fatigue. The
lower opening
force can improve the ability of the user to maintain control over the
container
components while removing the cover from the base and thus to reduce the
possibility
of spilling the contents stored in the container.
[0073] The use of the tenns "a," "an," "the," and similar referents in the
context
of describing the invention (especially in the context of the following
claims) are to be
construed to cover both the singular and the plural, unless otherwise
indicated herein
or clearly contradicted by context. Recitation of ranges of values herein are
merely
intended to serve as a shorthand method of referring individually to each
separate
value falling within the range, unless otherwise indicated herein, and each
separate
value is incorporated into the specification as if it were individually
recited herein. All
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16
methods described herein can be performed in any suitable order unless
otherwise
indicated herein or otherwise clearly contradicted by context. The use of any
and all
examples, or exemplary language (e.g., "such as") provided herein, is intended
merely
to better illuminate the invention and does not pose a limitation on the scope
of the
invention unless otherwise indicated.
[0074] While the invention is described herein in connection with certain
preferred embodiments, there is no intent to limit the present invention to
those
embodiments. On the contrary, it is recognized that various changes and
modifications to the described embodiments will be apparent to those skilled
in the art
upon reading the foregoing description, and that such changes and
modifications may
be made without departing from the spirit and scope of the present invention.
Skilled
artisans may employ such variations as appropriate, and the invention may be
practiced otherwise than as specifically described herein. Accordingly, the
intent is to
cover all alternatives, modifications, and equivalents included within the
spirit and
scope of the invention. Moreover, any combination of the above described
elements in
all possible variations thereof is encompassed by the invention unless
otherwise
indicated herein or otherwise clearly contradicted by context.
