Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
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IMPACT-RESISTANT CASE WITH SEALABLE OPENING
FIELD OF THE INVENTION
The present invention relates to an impact-resistant case with a sealable
opening, in
particularly to a dust and watertight seal.
BACKGROUND OF THE INVENTION
Electronic enclosures and housings are basically cases designed to provide
protection for product contents. Aesthetics, ergonomics, weight, decoration,
and additional
functionality are provided as well since the case is usually the basis of
human interface to the
product. This interface may be sensory (visual) only, or it may be the basis
for product use -
e.g. the user holds onto the package to use the product. For example, a
portable drill where
the case is also the tool housing and the housing is what the operator holds
to use the tool.
Consequently, the case is a multifunctional product in its own right and the
design is the result
of fulfilling all the necessary functional requirements.
Recent developments in portable electronics has resulted in the need for
ruggedized
supplemental cases for electronic products, such as web tablets, cell phones,
video and still
cameras, palm computers, etc. These specialized secondary enclosures allow
products
designed for office use to be usable in the outdoors under adverse conditions.
There are
numerous hazards for which a protective case may be required, two primary ones
being
impact (drop) and environmental (water and/or dust). Challenges arise when the
protection
functionality is combined with aesthetics or ergonomics.
Traditionally, a shipping case is designed to be energy absorbent. If energy
absorbency is the only requirement, many low cost options exist since
generally the larger the
case, the easier it is to design it to be energy absorbent. For example, foam
cubes can be
placed in a corrugated box between the fragile contents and the box (case) and
these blocks
will provide a high degree of impact protection. However, this approach yields
a large and
bulky package. If in addition to impact resistance, the case needs to provide
the "user
interface", this approach is typically much larger than is practical and, on a
sensory basis, it
will appear as large, unwieldy, and even ugly. As a user interface enclosure,
it's totally
impractical. Consequently, user preferred supplemental enclosures are
intensively designed
to minimize size, bulk, weight, and optimize ergonomics.
Most portable electronic devices have features that require access while
contained in
a supplemental enclosure, for example, a protective case. For example,
Personal Data
Assistants (PDAs) have removable memory cards, batteries, synch cables, andlor
power
cables. However, under typical operating conditions, it may be desirable to
use or access
these features without removing the product from its protective case. In
addition to the
energy absorbing requirement, incorporating a functional requirement, such as
access,
traditionally has resulted in increasing the number of parts, the complexity
to design and the
cost to manufacture a protective case. When size, weight, protection,
aesthetics,
ergonomics, user access and/or more are all required, the protective case
might end up with
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as much or more engineering as the basic product itself. The conventional
approach to this
problem has been to tailor the design of the protective case for portable
electronic device,
unfortunately, this approach is time consuming and expensive.
An alternative, cost effective, approach to provide a protective case for
portable
electronic devices having multiple functions, such as impact-absorbing and
internal access, is
needed.
SUMMARY OF THE INVENTION
The present invention is a cost effective impact-absorbing insert which
combines
multiple functionality with parts consolidation and ease of customization that
allows wide
application anywhere tailored impact protection is desired. The impact-
absorbing insert of the
present invention mates with a user defined enclosure to produce a protective
case for any
fragile article that is used in a portable environment, for example portable
electronic devices
such as cameras (35 mm and digital), instrumentation, tools, PDAs, web
tablets, hand held
computers, cell phones, a pagers, gaming devices, electronic music players,
voice recorders,
global positioning systems (GPS), and the like.
It is further objective of the invention to reduce part count and to improve
ease of use
of the impact-absorbing insert.
It is a still another objective of the invention to provide versatility by
designing an
impact-absorbing insert which can fit into one or more different user defined
enclosures. This
reduces the level of complex engineering necessary for each product while
allowing
sophisticated design of the energy absorbing features in the insert alone.
In one embodiment, the present invention is an impact-absorbing insert for a
protective case designed for containing and protecting a fragile article
wherein the insert
comprises one or more impact-absorbing portion and one or more tethered plug
for insertion
into an access tunnel contained in a mating user defined enclosure, wherein
said access
tunnel provides access to features of the article without opening the
protective case.
In another embodiment, the present invention is a protective case for a
fragile article
comprising the impact-absorbing insert of the present invention and a user
defined enclosure
wherein the protective case provides impact protection and, when the access
tunnel is
plugged, a water tight and dust tight seal for the fragile article.
In another embodiment, the impact-absorbing insert comprises a molded
polymeric
material, preferably a low hardness, highly elastic polymeric material such as
an elastomeric
thermoplastic or an elastomeric thermoset plastic, preferably thermoplastic
polyurethane.
Another embodiment of the invention is a method to retain the impact-absorbing
insert in a user defined enclosure by designing attachment features which
produce a tight fit
between the impact-absorbing insert with the user defined enclosure, for
example molded
fingers on the impact-absorbing insert and grooves on the user defined
enclosure, fingers on
the user defined enclosure and grooves are on the impact-absorbing insert, or
combinations
thereof.
In a further embodiment of the invention the impact-absorbing portion of the
impact-
absorbing insert comprises one or more of an integral energy absorbing web and
rib feature
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that compresses or deforms to absorb impact loading, molded-in buttons, ribs,
aesthetics
features, engagement ribs, interference tolerances to enable positive fit and
function for the
life of the article, or combinations thereof.
It is still another embodiment of the invention to allow easy manufacture of
the insert
by utilizing common injection molding technology and tooling with open and
shut operation.
Another embodiment of the invention is a protective case for a portable
electronic
device comprising the impact-absorbing insert of the invention inserted into a
user defined
enclosure which demonstrates an impact improvement provided to the user
defined
enclosure, and electronic product contained therein, sufficient to pass MIL-
STD-810F, Table
516.5-Vi Transit Drop Test at a minimum of 24 inches.
BRIEF DESCRIPTION OF THE DRAWINGS
Fig. 1 is an exploded perspective view from the inside of a protective case
for a
portable electronic device comprising an impact-absorbent insert and a mating
user defined
enclosure.
Fig. 2 is an exploded perspective view from the outside of a protective case
for a
portable electronic device comprising an impact-absorbent insert and a mating
user defined
enclosure.
Fig. 3 is an exploded perspective view of a web tablet with its protective
case
comprising an impact-absorbent insert and a mating user defined enclosure.
Fig. 4 is a perspective view of a protective case comprising an impact-
absorbent
insert and a mating user defined enclosure.
DETAILED DESCRIPTION OF THE INVENTION
The impact-absorbing insert 1 as shown in FIG. 1 has an outside surface 2 and
an
inside surface 3. Further, the impact-absorbing insert had one or more impact-
absorbing
portions 4 and one or more tethered plugs 5. At least a portion of the outside
surface of the
insert, for example the impact-absorbing section(s), is designed to fit within
the exterior
surface 21 of a user defined enclosure 20. The user defined enclosure
comprises a top
portion 22 and a bottom portion 23, each having an interior surface 24. The
user defined
enclosure comprising the impact-absorbing insert comprise a protective case 30
for a portable
electronic device 40 (Fig. 4).
Preferably, the outside surface of the impact-absorbing insert must fit
tightly against
the interior surface of the user defined enclosure. Any means to hold the
insert tightly against
the user defined enclosure is acceptable, for example, it can be held by an
adhesive, a
fastener, a mechanical means, or combination thereof. An example of a
mechanical means is
shown in Fig. 1. The insert is held by fingers 25 which are molded into the
interior surface of
the user defined enclosure which engage grooves 6 on the outside surface of
the insert.
Alternatively, the grooves can be on the interior surface of the user defined
enclosure and the
fingers on the outside surface of the insert or each surface can have one or
more groove, one
or more finger or any combination thereof.
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When a portable electronic device is placed within the protective case, it
must fit
tightly against the inside surface of the impact-absorbing insert. The outside
surface of the
insert preferably has integral ribs and standoff features 7 that (1 ) provide
clearance to prevent
the portable electronic device from contacting the interior surfaces of the
user defined
enclosure, and/or the ground in a drop impact, and (2) absorb energy resulting
from such a
drop. Further, the impact-absorbing insert may comprise one or more molded-in
button, rib,
access tunnel, aesthetics feature, tethered plug, engagement rib, or
interference tolerance to
enable positive fit and function for the life of the product. Such features
are designed for
specific functionality based on the portable electronic device and end product
needs.
Preferably, the impact-absorbing insert should have sufficient structure to
avoid
collapse in an impact situation and still be able to absorb the energy
resulting from such a
drop without damage to the portable electronic device it serves to protect. It
is preferable that
the insert has adequate flex fatigue resistance so as to recover its original
position after being
depressed when a drop or other impact occurs. It should be rigid enough to
maintain its
position within the user defined enclosure during normal use so as to minimize
unwanted
movement of the portable electronic device within the user defined enclosure.
Preferably, the impact-absorbing insert must have good solvent resistance and
good
long term creep properties so that it will not sag or warp over time. Further,
it is preferable
that the impact-absorbing insert have sufficient thermal resistance to enable
it to perform its
function in a wide range of climate conditions, preferably from - 40°F
(-40°C) to 120°F (49°C).
The enclosed portable electronic device may generate thermal issues as well
and the impact-
absorbing insert must withstand these without distortion or lack of
performance.
As shown in FIG. 2, the tethered plug 5 is integral with the impact-absorbing
portions
of the impact-absorbing insert. It comprises a plug portion 9 and a tether
portion 10. The
plug portion has an outside 11 and an inside surface 12. The tethered plug is
designed to
initially pass through and then fit snugly back into an opening or access
tunnel 26 in the user
defined enclosure. The access tunnel allows access from the outside of the
user defined
enclosure/protective case to the portable electronic device located inside of
the user defined
enclosurelprotective case without the need to open the user defined
enclosure/protective
case (for example to allow removal of a memory card, replace a battery,
attach/detach a
synch cable, insert/remove an earphone jack, insert/remove a power cable,
etc.). The plug is
designed to be insertable and removable from the outside surface of the user
defined
enclosure while remaining attached to the impact-absorbing portions) of the
insert, which is
on the inside surface of the user defined enclosure, by a tether that passes
through the user
defined enclosure opening. When the plug is inserted into the access tunnel,
from the outside
of the user defined enclosure, it preferably forms a water tight and/or dust
tight seal. The
impact-absorbing insert may have multiple tethered plugs for sealing matching
multiple
access tunnels in the user defined enclosure depending on the specific
requirements of the
portable electronic device which is incased within the protective case.
Preferably the impact-absorbing insert is molded with a nominal wall thickness
equal
to or greater than about 2 millimeter (mm) with integral feature (impact-
absorbing portion,
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tether, plug, etc.) thicknesses preferably equal to or greater than about 1
mm, more preferably
equal to or greater than about 1.5 mm and most preferably equal to or greater
than about 2
mm. The maximum nominal wall and integral feature thicknesses are only limited
by what is
practical for the specific enclosure and portable electronic device, but
generally, they are
equal to or less than about 25 mm, preferably equal to or less than about 12
mm, and most
preferably equal to or less than about 6 mm.
The impact-absorbing insert can be made from any polymeric material which can
(1)
be manufactured with the necessary geometric design and (2) will hold its
shape through time
in a wide range of environments When fitted into the user defined enclosure.
Preferably, the
polymeric material is a thermoplastic or thermoset elastomer. Suitable
elastomers are
described, for example, in Billmeyer, F., Textbook of Polymer Science,
Interscience
Publishers, New York, N.Y. (1965) and in ifirk-Othmer Science of Chemical
Technology 4tn
Ed, John Wiley & Sons, New York, N.Y. (1993).
The impact-absorbing insert can be made from any elastomeric plastic,
thermoplastic
or thermoset with low modulus and high elasticity. Preferably, the impact-
absorbing insert is
made from a material having a hardness between about Shore 40 A to about Shore
65 D.
Preferably the insert is made from polyamide (PA); polyurethane (PU);
polyolefin
(PO), such as polyethylene (PE), such as low density polyethylene (LDPE),
polypropylene
(PP), ethylene and vinyl acetate copolymer (EVA), ethylene and propylene
copolymer (EP),
polyethylene and alpha-olefin co-polymer, such as ENGAGET"" polyolefin
elastomers
available from The Dow Chemical Company, thermoplastic polyolefin (TPO);
polyvinyl
chloride (PVC); polyester; polysiloxane; and mixtures thereof. Preferably the
impact-
absorbing insert is made from a thermoplastic polyurethane (TPU), such as
PELLETHANET""
2102-75A polyurethane available from The Dow Chemical Company.
The impact-absorbing insert of the present invention can be made by any known
molding process including injection molding, transfer molding, reaction
injection molding, or
liquid injection molding.
EXAMPLE
The following example serves to demonstrate an embodiment of the invention but
is
not intended to limit the scope of the invention.
PELLETHANE 2102-75A thermoplastic polyurethane resin is injection molded into
a
designed geometry mold cavity in the shape of an impact-absorbing insert
measuring 218 mm
x 30 mm x 37 mm with a nominal wall thickness of 2 mm. This design is the
result of
combining the fit functionality between a portable electronic device, a user
defined enclosure
having two access tunnels, and an impact-absorbing insert with the energy
absorbing
features (ribs, standoffs, and fingers) and two tethered plugs for the access
tunnels. All the
geometry necessary for correct functionality is designed into the part and
transferred to the
metal mold, which reproduces the requisite geometry to all parts manufactured
by it. The
manufacture of the part is such that each time the mold opens, a complete,
impact-absorbing
insert is ejected. The impact-absorbing insert contains the necessary impact
absorption
features and tethered plugs all in one molded article.
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The PELLETHANE 2102-75A TPU resin is dried at a temperature between
80°C to
95°C and the molding conditions are a melt temperature between
200°C to 215°C with a mold
temperature between 15°C to 60°C. An Engel 25mm single screw
injection molding machine
is used.
The resulting impact insert is placed into a user defined enclosure (also
molded from
PELLETHANE 2102-75A TPU resin) having a top and bottom portion, such that the
impact-
absorbing insert is placed in the top portion and mates with a recess in the
top portion of the
protective user defined enclosure. A personal electronic device, for example a
web tablet, is
placed in the protective user defined enclosure and fits snuggly against the
impact-absorbing
insert. The access tunnels in the user defined enclosure line up with the
access features of
the electronic device and when the tethered plugs on the impact-absorbing
insert are inserted
into these access tunnels a water and dust tight seal is formed.
The top portion of the user defined enclosure is mated with the bottom portion
of the
user defined enclosure. The resulting protective case provides the encased
portable
electronic device water and dust resistance, impact protection, and access to
features within
the user defined enclosure.
The protective case comprising a portable electronic device, the user defined
enclosure, and the impact-absorbing insert is subjected to the MIL-STD-810F,
Table 516.5-VI
Transit Drop Test and passes at a minimum of 24 inches.
Table 516.5-VI testing protocol is:
~ To pass, the unit must survive 26 drops at a specific height without damage
(defined as impaired functional use) to the portable electronic device.
~ Up to five units may be used to obtain the 26 drops.
~ Use five different units for each drop height (24 in. (70 cm), 30 in. (76
cm), 36 in.
(91 cm), 42 in. (107 cm), 48 in. (122 cm), etc.)
~ The units are dropped onto concrete covered with two layers of 0.5 inch
plywood.
~ Drop Sequence:
1. Drop on each of the 6 faces 3 times (18 drops total). Evenly spread these
drops over 3 units.
2. Drop on each of the 4 corners 2 times (8 drops total).
3. Repeat at next drop level if 26 passing drops are achieved.
As can be seen by the preceding example, the present invention provides a cost
effective impact-absorbing insert which combines multiple functionality with
parts
consolidation and ease of customization that provides good impact protection
to the encased
portable electronic device.
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