Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
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RECLOSABLE CONTAINER AND CLOSURE THEREFOR
FIELD OF THE INVENTION
The invention relates to a reclosable food container comprising a tray and a
lid, and
to easy opening closures for such containers.
BACKGROUND OF THE INVENTION
Food products such as meats are often packaged for sale in reclosable, rigid
or
semi-rigid plastic containers comprising a tray and a lid. Prior to first
opening of
the container, the food product is enclosed within a hermetically sealed
product
compartment within the tray. Upon first opening of the container, the hermetic
seal
is destroyed. The container can then be reclosed by applying the lid to the
tray, for
example to maintain freshness of unused portions of the food product for a
relatively short period of time. A hermetic seal is not formed between the lid
and
tray when the container is reclosed.
Convenience and ease of use are important properties of these containers, and
may
have an impact on acceptance of a particular food product by consumers. It is
common for reclosable food containers to incorporate a detent mechanism to
provide an interlocking or "snap" fit between the tray and the lid. Such
detent
mechanisms may provide an audible sound and/or a tactile sensation which
assures
the user that the lid has snapped into engagement with the tray and that the
container is therefore closed. The detent mechanism may be in the form of one
or
more ribs or similar protrusions extending along the edges of the tray and/or
lid.
One problem with such a detent closure mechanism is that it may make it more
difficult to apply or remove the lid from the tray. For example, it may be
necessary
to firmly press the lid onto the tray about-its entire periphery to engage the
detent
mechanism, and to gradually peel the lid from the tray to disengage the detent
mechanism. On the other hand, the complete absence of a detent mechanism
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would cause the lid to fit loosely on the tray and make it difficult to keep
the tray
closed.
There remains a need for a reclosable food container which can be easily
opened
and reclosed, yet provides a reliable closure with an audible noise and/or a
tactile
sensation to signify complete engagement of the lid and the tray.
SUMMARY OF THE INVENTION
In one aspect, the invention provides a reclosable container for a food
product. The
container comprises a tray having a base and an upstanding sidewall extending
from the base. The base and the sidewall together define a compartment for the
food product, and the sidewall terminates in a peripheral edge portion.
The container further comprises a lid having a central panel surrounded by a
peripheral edge portion. The peripheral edge portions of the tray and lid each
have
four sides and four corners, and each comprise an inner wall, an outer wall
spaced
from the inner wall, and a flange connecting the inner and outer walls at
their upper
edges. The inner wall of the tray peripheral edge portion extends upwardly
from
the sidewall, and the inner wall of the lid peripheral edge portion extends
upwardly
from the central panel.
The container further comprises a first outer detent mechanism which is
located at
a first corner of the lid peripheral edge portion and a corresponding first
corner of
the tray peripheral edge portion. The first outer detent mechanism comprises a
male detent element projecting inwardly from the outer wall of the lid
peripheral
edge portion and a female detent element projecting inwardly from the outer
wall
of the tray peripheral edge portion. The male and female detent elements are
positioned so that the male detent element is nested with the female detent
element when the container is closed.
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In another aspect, the peripheral edge portions of the tray and the lid are
generally
rectangular.
In yet another aspect, the first corner at which the first outer detent
mechanism is
located is shaped to define a first corner transition portion which forms an
included
angle of greater than 90 degrees with each of the adjoining sides, and the
first
outer detent mechanism is located at the first corner transition portion. For
example, the first outer detent mechanism may be provided in the substantially
straight portion of the first corner transition portion.
In yet another aspect, the first corner transition portion includes a
substantially
straight portion which forms an included angle of about 135 degrees with each
of
the adjoining sides.
In yet another aspect, the male detent element of the outer detent mechanism
projects inwardly at an angle of about 45-90 degrees to the outer wall of the
lid
peripheral edge portion, and the female detent element projects inwardly at an
angle of about 45-90 degrees to the outer wall of the tray peripheral edge
portion.
The angle of about 45-90 degrees is defined in a vertical plane passing
through the
first outer detent element. In another aspect, the angle is from about 60-90
degrees.
In yet another aspect, the male detent element projects sharply and abruptly
inwardly from the outer wall of the lid peripheral edge portion, and the
female
detent element projects sharply and abruptly inwardly from the outer wall of
the
tray peripheral edge portion, when the male and female detent elements are
viewed in a vertical plane passing through the first outer detent element.
In yet another aspect, the male and female detent elements each comprise one
or
more dimples having upper and lower surfaces spaced from the respective upper
and lower edges of the outer walls of the tray and lid peripheral edge
portions.
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In yet another aspect, the container further comprises a second outer detent
mechanism located at a second corner of the lid peripheral edge portion and a
corresponding corner of the tray peripheral edge portion. The second outer
detent
mechanism is the same as the first outer detent mechanism. The first and
second
corners at which the first and second outer detent mechanisms are located may
be
located diagonally opposite to one another. Furthermore, the second corner may
be shaped to define a second corner transition portion at which the second
outer
detent mechanism is located, with the second corner transition portion
including a
substantially straight portion which forms an included angle of about 135
degrees
with each of the adjoining sides.
In yet another aspect, the container may further comprise at least one lift
tab
extending outwardly from the outer wall of the lid peripheral edge portion at
the
corner at which the first outer detent mechanism is located.
In yet another aspect, the inner and outer walls of the tray and lid
peripheral edge
portions are substantially flat and planar along the sides thereof.
In yet another aspect, the inner and outer walls of the tray and lid
peripheral edge
portions are substantially free of projections along the sides thereof.
BRIEF DESCRIPTION OF DRAWINGS
The invention will now be described, by way of example only, with reference to
the
accompanying drawings in which:
Figure 1is a perspective view of a reclosable container according to the
invention,
with the lid applied to the tray;
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Figures 2 and 3 are perspective views of the container of Figure 1, showing
the lid
being separated from the tray;
Figure 4 is a cross-section along line 4-4 of Figure 1;
Figure 5 is a cross-section along line 5-5 of Figure 1;
Figure 6 is a cross-section similar to Figure 5, but showing the lid separated
from
the tray;
Figure 7 is a cross-section along line 7-7 of Figure 1;
Figure 8 is a perspective view of a corner of a container according to a
second
embodiment of the invention; and
Figure 9 is a cross-sectional plan view through the upper flange at the corner
shown in Figure 8.
DETAILED DESCRIPTION
A reclosable container 10 for a food product is illustrated in the drawings,
and is
now described below.
The reclosable container 10 comprises a tray 12 and a lid 14, both of which
may be
made from a rigid or semi-rigid plastic film which is formed into the
illustrated
shapes by application of heat and/or pressure. In the illustrated container 10
the
tray 12 and lid 14 are made from a transparent plastic film, but it will be
appreciated that the tray 12 and/or lid 14 could instead be formed from
translucent
or opaque plastic films.
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The following description uses terms such as "upper", "lower", "upward",
"downward", "top", "bottom", "vertical", "horizontal" and variants of these
terms to
indicate position and orientation of certain elements of the container 10. It
will be
understood that these terms are used to describe the orientation of the
container
as illustrated in the drawings, in which the lid 12 is generally shown to be
on top
of the tray 14 and the tray 12 is resting on its base. Also, terms such as
"inner",
"outer", "inward" and "outward" and variants thereof are used for descriptive
purposes in order to indicate relative distance from a center of the tray 12
or the lid
14.
The tray 12 comprises a generally flat base 16 on which the container 10 is
supported. The base 16 is generally rectangular in shape, having a periphery
defined by two relatively long edges 18 and two relatively short edges 20
joined by
rounded corners, with at least the long edges 18 being outwardly convex
relative to
the center of the base 16. The tray 12 further comprises a sidewall 22 which
surrounds the base 16 and defines the four sides of the tray 12, extending
upwardly and outwardly from the edges 18, 20 of base 16. The sidewall 22
includes a lower, outwardly sloped portion 24 and an upper, substantially
vertical
portion 26 which has a generally rectangular outer periphery. The base 16 and
sidewall 22 of tray 12 together define at least part of a product compartment
for a
food product such as meat (not shown). The illustrated container 10 is
particularly
well suited for packaging of elongate meat products, such as bacon strips. It
will be
appreciated, however, that other types of food products may be packaged in
container 10, and that the shape and dimensions of the tray 12 and lid 14 may
be
adjusted so as to provide a product compartment suitable to receive other food
products.
The tray 12 further comprises a peripheral edge portion 30 which extends
upwardly
from the vertical portion 26 of sidewall 22 and is generally rectangular in
shape.
The peripheral edge portion 30 of tray 12 (also referred to herein as the
"tray
peripheral edge portion") is further described below.
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The lid 14 is also generally rectangular in shape so as to completely cover
the open
top of tray 12, and comprises a flat central panel 32 surrounded by a
peripheral
edge portion 34. The peripheral edge portion 34 of the lid 14 (also referred
to
herein as the "lid peripheral edge portion") is further described below.
As shown in the drawings, the tray and lid peripheral edge portions 30, 34,
the
base 16, the sidewall 22 and the central panel 32 are all generally
rectangular, each
having four sides. This provides the container 10 with an overall elongate,
rectangular shape. This rectangular shape is best seen in the plan view of
Figure 4.
It will be appreciated that the shape of container 10 may be varied so that
the four
sides of the base 16, sidewall 22, central panel 32 and peripheral edge
portions 30,
34 are all of substantially the same length so that the container 10 has an
overall
square shape when viewed in plan. Throughout the following description, unless
otherwise indicated, the term "rectangular" is to be understood as including
square
shapes.
Alternatively, some or all of the angles between the four sides of the base
16,
sidewall 22, central panel 32 and peripheral edge portions 30, 34 may be
greater or
less than 90 degrees such that the container 10 has an overall shape of a
rhombus,
parallelogram, trapezoid or other four-sided polygon when viewed in plan.
Alternatively, the container according to the invention is not necessarily
four-sided,
but may be in the shape of a triangle, pentagon, hexagon or other polygonal
shape.
The elements making up the tray and lid peripheral edge portions 30, 34 are
substantially identical to one another, and are therefore identified in the
drawings
with like reference numerals, with the reference numerals of the lid
peripheral edge
portion 34 being primed. For the sake of convenience, the following
description
uses the same reference numerals to identify the elements of the peripheral
edge
portions 30, 34, except where it is necessary to distinguish between the tray
and lid
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peripheral edge portions 30, 34, in which case the elements of the lid
peripheral
edge portion 34 are identified by primed reference numerals.
As shown in the drawings, the tray and lid peripheral edge portions 30, 34
each
have four sides connected by four corners. The four sides are identified by
reference numerals 36, 38, 40, 42 and the four corners are identified by
reference
numerals 44, 46, 48, 50. The sides 36, 38, 40, 42 are shown as being
substantially
straight, although this not necessarily the case. Rather, the sides may be
either
concavely or convexly curved relative to the center of the container 10.
Adjacent
pairs of sides 36, 38, 40, 42 of container 10 are shown as being at right
angles to
one another. It will be appreciated that this is not essential. Rather, the
angle
between adjacent sides 36, 38, 40 and 42 may be either less than or greater
than
90 degrees without departing from the scope of the invention.
The corners 44, 46, 48, 50 are not square, but rather are shaped so as to
define
corner transition portions which may, for example, be rounded or chamfered so
as
to form an included angle greater than the included angle between the two
sides to
which they are joined which, in the illustrated embodiment, is about 900.
These
corner transitions are now described below in greater detail.
The tray and lid peripheral edge portions 30, 34 both include two diagonally
opposed corners 44, 48 which are rounded so as to form smoothly curved corner
transition portions extending between two adjoining sides, each describing an
arc of
approximately 90 degrees. For example, as shown in the plan view of Figure 4,
an
included angle 0 between a tangent T at any point along the curved transition
portion of corner 44, and either of the sides 36, 38 to which it is joined, is
greater
than about 900.
Both the tray and lid peripheral edge portions 30, 34 also include two
diagonally
opposed corners 46, 50 which are chamfered so as to form substantially
straight
transition portions 52, 54 extending between two adjoining sides. For example,
as
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shown in Figure 4, the straight transition portion 52 at corner 46 forms an
included
angle (3 of about 135 with both of the sides 38, 40 to which it is joined.
Also as
shown in Figure 4, a smoothly curved transition may be formed between the
straight portions 52, 54 and the sides to which they are joined.
The provision of two different corner shapes and the positioning of similarly
shaped
corners diagonally opposite to one another ensure that the lid 14 can only be
applied to tray 12 in one orientation. The significance of this feature will
become
apparent from the description below.
The cross-sectional shapes of the peripheral edge portions 30, 34 are now
described below with reference to Figures 4 to 7. As seen in the cross-
sections, the
tray and lid peripheral edge portions 30, 34 are generally U-shaped in cross-
section
and are made up of three elements: an inner wall 56, an outer wall 58 which is
spaced from the inner wall 56, and a flange 60 connecting the inner and outer
walls
56, 58 at their upper edges. Each of these elements extends about the entire
peripheral edge portions 30, 34 of both the tray and lid 12, 14, including all
four
sides 36, 38, 40, 42 and all four corners 44, 46, 48, 50.
In the embodiment shown in the drawings, the inner and outer walls 56, 58 are
both substantially vertical and parallel to one another, and the flange 60 is
substantially horizontal. Also, for reasons which will become apparent below,
the
portions of the inner and outer walls 56, 58 which extend along the sides 36,
38,
40, 42 are substantially flat and planar and are free of projections.
Furthermore,
the flange 60 is substantially flat and planar and, as shown in Figure 7, a
rounded
or chamfered transition may be provided between the flange 60 and the
adjoining
inner and outer walls 56, 58, particularly along the sides 36, 38, 40, 42 of
the
peripheral edge portions 30, 34.
As can be seen from Figure 7, the inner wall 56 of the tray peripheral edge
portion
30 extends upwardly from the upper edge of sidewall 22. In the container 10
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shown in the drawings, the sidewall 22 includes an upper vertical portion 26
and
therefore there is no clear transition between the upper edge of the sidewall
22 and
the inner wall 56, at least along the sides 36, 38, 40, 42. For the purpose of
this
description, it will be assumed that the lower edge of the inner wall 56 of
the tray
peripheral edge portion 30 is coplanar with the central panel 32 of lid 14
when the
container 10 is closed as shown in Figure 7. The lower edge of inner wall 56
and
the upper edge of sidewall 22 are both identified by reference numeral 61 in
the
drawings.
The inner wall 56' of the lid peripheral edge portion 34 extends upwardly from
the
central panel 32, and therefore the panel 32 is inset relative to the
peripheral
flange 60', which is beneficial for stacking of containers 10.
When the container 10 is closed, the tray peripheral edge portion 30 is
substantially
completely nested inside a cavity defined by the walls, 56, 58 and flange 60
of the
lid peripheral edge portion 34. With the peripheral edge portions 30, 34
nested as
shown in Figure 7, the inner wall 56, outer wall 58 and flange 60 are in
substantial
engagement with the inner wall 56', outer wall 58' and flange 60' of the lid
peripheral edge portion 34. In order to permit nesting of the peripheral edge
portions 30, 34, the flange 60 of the tray peripheral edge portion 30 is
slightly
narrower than the flange 60' of the lid peripheral edge portion 34.
The container 10 is also provided with at least one detent mechanism which is
formed in the outer walls 58 of both the tray and lid peripheral edge portions
30,
34, and is therefore referred to herein as the "outer detent mechanism" and
generally identified by reference numeral 62. In the embodiment shown in the
drawings, container 10 is provided with two such outer detent mechanisms 62,
one
located at each of the chamfered corners 46, 50. The outer detent mechanism 62
is now described with reference to the Figures 5 and 6, comprising vertical
cross-
sections through chamfered corner 50 in the closed (Fig. 5) and opened (Fig.
6)
configurations.
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Each outer detent mechanism 62 comprises a male detent element 64 projecting
inwardly from the outer wall 58' of the lid peripheral edge portion 34, and a
corresponding female detent element 66 projecting inwardly from the outer wall
58
of the tray peripheral edge portion 30. When the container 10 is closed as
shown in
Figure 5, with the tray peripheral edge portion 30 substantially completely
received
within the lid peripheral edge portion 34, the male detent element 64 is
received
within, and nested with, the female detent element 66. It is therefore
apparent
from Figure 5 that the male and female detent elements 64, 66 in each outer
detent mechanism 62 must be positioned directly opposite one another on the
respective outer walls 58, 58' of the peripheral edge portions 30, 34. In the
outer
detent mechanism 62 shown in the drawings, the male detent element 64 is made
up of a series of discrete protrusions or dimples, and the female detent
element
similarly comprises a series of discrete projections or dimples of slightly
greater
size. More specifically, each of the male and female detent elements 64, 66 is
made up of two such projections or dimples in the illustrated embodiment of
Figures 1 to 7.
It will be appreciated that the detent mechanism 62 may comprise fewer or more
male and female detent elements 64, 66 than shown in Figures 1 to 7, and that
the
detent elements 64, 66 may be shaped differently from those shown in Figures 1
to
7. For example, Figures 8 and 9 show a slight variant of one corner 46 of
container
in which the outer detent mechanism 62 comprises only one male detent
element 64 and only one female detent element 66, each comprising an elongate
rib. The number and size of the detent elements 64, 66 is at least partly
determined by the desired amount of force needed to open and close container
10.
For example, it would be expected that the detent mechanism 62 of Figures 8
and
9, having relatively enlarged detent elements 64,. 66, would require slightly
more
force to open and close than the detent mechanism 62 of Figures 1 to 7.
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The angle which the detent elements 64, 66 make with the outer walls 58, 58'
of
the tray and lid peripheral edge portions 30, 34 also has an impact on the
force
required to open and close the container 10. In the examples shown in the
drawings, the detent elements 64, 66 project inwardly from outer walls 58, 58'
at
an angle in the range of about 45-90 degrees from vertical, for example about
60-
90 degrees from vertical, at least when viewed in a cross-section in a
vertical plane,
as in Figures 5 and 6. For example, when viewed in a vertical plane passing
through the detent elements 64, 66, sharp, abrupt transitions are formed
between
the upper and lower surfaces of detent elements 64, 66 and the outer walls 58,
58',
and the angles between the upper and lower surfaces of detent elements 64, 66
and the outer walls 58, 58' fall within the ranges mentioned above. Since the
lid 14
is removed by pulling upwardly and outwardly, the angle between the detent
elements 64, 66 and the outer walls 58, 58', when viewed in a cross-section in
a
horizontal plane, as shown in Figure 4, is less critical, and may be less than
the
ranges mentioned above.
The shape of the detent elements 64, 66 is such that a significant force is
required
to engage and disengage the outer detent elements 64, 66 relative to their
small
area. A pair of such outer detent mechanisms 62 at diagonally opposite corners
is
sufficient to keep the lid 14 from accidentally becoming separated from tray,
and
also provides the user with a definite audible and/or tactile sensation to
indicate
that the container 10 is either open or closed.
The container 10 further comprises at least one lift tab 68 projecting
outwardly
from the lower edge of the outer wall 58' of lid peripheral edge portion 34.
The lift
tab 68 provides an area to be gripped by the user and pulled upwardly to
separate
the lid 14 from the tray 12, thereby opening the container 10 as shown in
Figures 2
and 3. Although container 10 includes two lift tabs 68 to permit the container
10 to
be opened from either end, it will be appreciated that only one tab 68 needs
to be
lifted during opening of the container 10. Therefore, container 10 could be
provided with only one lift tab 68 without affecting ease of opening.
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The lift tabs 68 are located at the chamfered corners 46, 50 at which the
outer
detent mechanisms 62 are located. More specifically, the lift tabs 68 extend
outwardly from the straight portions 52, 54 of the chamfered corners 46, 50
and
are directly aligned with the detent elements 64, 66. This permits the detent
mechanisms 62 at each chamfered corner 46, 50 to become easily disengaged by
lifting the tab 68.
The container 10 may also be provided with at least one detent mechanism which
is
formed in the inner walls 56 of both the tray and lid peripheral edge portions
30,
34, and is therefore referred to herein as the "inner detent mechanism" and
generally identified by reference numeral 70. An inner detent mechanism 70 may
be provided at one or more corners of container 10, and or at least the
corners 46,
50 which also have an outer detent mechanism 62. In the specific embodiment
shown in the drawings, all four corners 44, 46, 48, 50 are provided with an
inner
detent mechanism 70. The inner detent mechanism 70 is now described with
reference to Figures 4 to 6.
Each inner detent mechanism 70 comprises a male detent element 72 projecting
outwardly from the inner wall 56' of the lid peripheral edge portion 34, and a
corresponding female detent element 74 projecting outwardly from the inner
wall
56 of the tray peripheral edge portion 30. As with the outer detent mechanism
62
described above, the male and female elements 72, 74 of the inner detent
mechanism 70 are also positioned so that the male detent element 72 becomes
nested with the female detent element 74 when the container 10 is closed as
shown
in Figure 5.
The male and female element 72, 74 of the inner detent mechanism 70 are shaped
so as to engage one another relatively weakly compared to the outer detent
mechanism 62. Therefore, the inner detent mechanisms 70 by themselves provide
little resistance against opening or closing of container 10.
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In the embodiment shown in the drawings, the male and female detent elements
72, 74 are in the form of horizontally elongated ribs. When viewed in the
vertical
cross-sections of Figures 5 and 6, it can be seen that the detent elements 72,
74
extend downwardly from the upper flange 60 and along the inner wall 56 of the
tray and lid peripheral edge portions 30, 34. The detent elements 72, 74 slope
outwardly and downwardly at a small angle from vertical and are therefore
somewhat wedge-shaped when viewed in cross-section. Due to the small angle at
which they are sloped, the detent elements 72, 74 engage each other weakly, so
that very little force is required to engage or disengage the inner detent
elements
72, 74. Moreover, the amount of force required to engage or disengage detent
elements 72, 74 is significantly less than that required to engage and
disengage the
male and female elements 64, 66 of the outer detent mechanism 62.
As shown in Figure 4, which is a horizontal cross-sectional or plan view
showing
tray 12 in isolation, each inner detent mechanism 70 wraps around one of the
corners 44, 46, 48, 50 and extends along portions of two adjoining sides 36,
38,
40, 42. Despite the fact that each inner detent mechanism 70 occupies
significantly
greater area than each outer detent mechanism 62, the small angle of slope
referred to above ensures that the detent elements 72, 74 engage each other
weakly.
Aside from the portions of the detent mechanisms 70 which extend past the
corners
44, 46, 48, 50 of the tray and lid peripheral edge portions, the sides 36, 38,
40, 42
are substantially flat and planar, and free of projections. This is
illustrated in Figure
7, showing a cross-section transverse to the elongate sides 36, 40. Along the
sides
of the tray and lid peripheral edge portions 30, 34, the inner and outer
sidewalls
56, 58 are substantially flat, vertical and parallel to one another.
Therefore, any
frictional engagement between the tray and lid peripheral edge portions 30, 34
along the sides 36, 38, 40, 42 offers very little resistance to opening and
closing of
the container 10.
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Opening of container 10 will now be described with reference to Figures 1 to
3.
Figure 1 shows the container 10 in its closed configuration, either before or
after
initial opening and removal of a portion of the food product (not shown).
Figures 2
and 3 show the container 10 in a partially opened state, from slightly
different
angles. In the closed configuration of Figure 1, the tray peripheral edge
portion 30
is substantially completely received within the lid peripheral edge portion 34
about
its entire periphery, as in Figures 5 and 7, so that the inner wall 56, outer
wall 58
and flange 60 of the tray peripheral edge portion 30 are in substantial
engagement
with the respective inner wall 56', outer wall 58' and flange 60' of the lid
peripheral
edge portion 34. In the closed configuration, the male and female elements 64,
66
of each outer detent mechanism 62 are in nested engagement as shown in Figure
5, as are the male and female elements 72, 74 of each inner detent mechanism
70.
With the container 10 closed, the lift tabs 68 project horizontally outwardly
of the
outer periphery of tray 12. To open the container 10, the user (not shown)
grasps
one of the lift tabs 68 and pulls it upwardly and outwardly. In the following
description, the container 10 is opened using tab 68 located at chamfered
corner
46. Therefore, unless otherwise indicated below, the tab 68 and the
corresponding
outer detent mechanism 62 referred to in the following discussion are those
located
at chamfered corner 46.
Due to the direct proximity between each lift tab 68 and the corresponding
outer
detent mechanism 62, the initial pulling and lifting of tab 68 is sufficient
to
overcome the force of the outer detent elements 64, 66, causing them to become
disengaged from one another. The plastic film has some "give" and therefore
pulling and lifting of the tab 68 results in some outward displacement of the
outer
wall 58' of the lid peripheral edge portion 34 (possibly accompanied by inward
displacement of the outer wall 58 of the tray peripheral edge portion 30), to
assist
in disengagement of the detent elements 64, 66. The disengagement of the outer
detent elements 64, 66 may be accompanied by a tactile sensation and/or an
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audible sound to indicate that the lid 14 has become separated from tray 12 at
corner 46. The male and female elements 72, 74 of inner detent mechanism 70 at
corner 40 also become disengaged during lifting of tab 68, and offer little
resistance
to opening.
Once the detent mechanisms 62, 70 at corner 46 are disengaged, the user
continues to lift tab 68 as shown in Figures 2 and 3 to progressively lift the
lid 14
away from tray 12. First, the sides 38', 40' of lid peripheral edge portion 34
adjoining corner 46' become separated from the tray peripheral edge portion
30.
The flat, planar shape of the inner and outer walls 56, 58 (Fig. 7) along the
sides
38, 40 offer little resistance against separation of the lid 14 from tray 12.
Continued lifting of the tab 68 results in the disengagement of the inner
detent
mechanisms 70 located at rounded corners 44, 48, possibly with a further
audible
sound or tactile sensation. Once these inner detents 70 are disengaged, the
two
remaining sides 38', 42' of the lid peripheral edge portion 34 are easily
separated
from the tray peripheral edge portion 30 by continued lifting of tab 68, such
that
the only remaining point of engagement between tray 12 and lid 14 is at the
chamfered corner 50 where the other outer detent mechanism 62 is located. This
configuration is shown in Figures 2 and 3.
Once the lid is lifted to the extent shown in Figures 2 and 3, further lifting
of the tab
68 causes the lid 14 to pivot at corner 50, about an axis which is either
coincident
with or in close proximity to the straight portion 54 of the chamfer at corner
50.
This pivoting motion causes the outer wall 58' of the lid peripheral edge
portion 34
to pivot away from the outer wall 58 of the tray peripheral edge portion 30.
This
results in outward displacement, and ultimate disengagement, of the male
detent
element 64 from the female detent element 66 at corner 50. Similarly, the
pivoting
movement of lid 14 overcomes the relatively weak resistance of the inner
detent
mechanism 70 at corner 50. The disengagement of detent mechanisms 62, 70 at
corner 50 results in complete disengagement and removal of lid 14 from tray
12.
CA 02695320 2010-03-04
17
The disengagement of the outer detent mechanism 62 at corner 50 may be
accompanied by an audible sound and/or a tactile sensation.
It will be appreciated that the pivoting of the lid 14 about the straight
portion 54 at
corner 50 permits the lid 14 to be removed without the need for the user to
pull or
lift the tab 68 at corner 50. In this way, the container 10 according to the
invention
is opened with one lifting movement.
Closing of container 10 is accomplished by placing the lid 14 over the open
tray 12
with the lid peripheral edge portion 34 overlying the tray peripheral edge
portion
30. The user then pushes down on the lid 14 or the lid peripheral edge portion
34
so as to push the lid peripheral edge portion 34 over the tray peripheral edge
portion 30 until the container is completely closed as in Figures 5 and 7. For
example, the user need only push down at chamfered corners 46, 50 to
completely
close the tray 10. The engagement of the outer detent mechanisms 62 at corners
46, 50 may be accompanied by an audible sound or a tactile sensation.
Although the invention has been described above with reference to a specific
container 10, it will be appreciated that modifications to the container can
be made
without departing from the scope of the invention. For example, due to the
fact
that the inner detent mechanisms 70 provide only weak engagement between the
tray 12 and lid 14, the inner detent mechanisms 70 may be completely
eliminated
or may be located at fewer than four corners without significantly affecting
the
opening and closing of the container.
Although container 10 does not include an outer detent mechanism 62 at the two
rounded corners 44, 48, it will be appreciated that this is not necessarily
the case.
For example, the container 10 may be modified by adding an outer detent
mechanism at these corners, which may be of the same or different
configuration
as the outer detent mechanisms 62 located at chamfered corners 46, 50. Where
the resulting container has strongly engaging outer detent mechanisms 62
located
CA 02695320 2010-03-04
18
at each corner 44, 46, 48, 50, the container will be somewhat more resistant
to
opening and closing. It is also possible to provide corners 44, 48 with weakly
engaging outer detent mechanisms similar in configuration to the weakly
engaging
inner detent mechanisms 70 described above.
In the outer detent mechanism 62 described above, the male detent element 64
projects inwardly from the outer wall 58' of the lid peripheral edge portion
34 and
the female detent element 66 projects inwardly from the outer wall 58 of the
tray
peripheral edge portion 30. It will be appreciated, however, that the
configuration
of the detent elements can be reversed such that male detent element 64
projects
outwardly from the outer wall 58 of the tray peripheral edge portion 30 and
the
female detent element 66 projects outwardly from the outer wall 58' of the lid
peripheral edge portion 34.
Although the invention has been described in connection with certain preferred
embodiments, it is not limited thereto. Rather, the invention includes all
embodiments which may fall within the scope of the following claims.
