U.S. patent application number 11/303137 was filed with the patent office on 2007-06-21 for methods and apparatus for a rugged mobile device housing.
This patent application is currently assigned to Symbol Technologies, Inc.. Invention is credited to Timothy Austin, Vikram Bhargava, Thomas Wulff.
Application Number | 20070138920 11/303137 |
Document ID | / |
Family ID | 38172638 |
Filed Date | 2007-06-21 |
United States Patent
Application |
20070138920 |
Kind Code |
A1 |
Austin; Timothy ; et
al. |
June 21, 2007 |
Methods and apparatus for a rugged mobile device housing
Abstract
A rugged mobile device housing is provided for protecting a
component (e.g., a liquid crystal display, a keyboard, a printed
circuit board, or the like) and includes one or more first
structures comprising a first material provided in a region of the
housing capable of withstanding deflection, wherein the first
material is an elastomer, and one or more second structures bonded
to the first structure, wherein the second structure is a
high-stiffness plastic. In one embodiment, the first material is a
high-stiffness elastomer and the second material is a long glass
fiber filled thermoplastic ("LGF" plastic). In one embodiment, the
first structure is located at a corner of the housing and the
second structure is located in the middle of the housing. In
another embodiment, the first structure is located in the center of
the housing and the second structures are located at the ends. In
yet another embodiment, a projecting handle and hinge are provided,
where the first structure is located at the handle and the second
structure is located at the hinge.
Inventors: |
Austin; Timothy; (Stony
Brook, NY) ; Bhargava; Vikram; (Nesconsel, NY)
; Wulff; Thomas; (North Patchogue, NY) |
Correspondence
Address: |
INGRASSIA FISHER & LORENZ, P.C.
7150 E. CAMELBACK, STE. 325
SCOTTSDALE
AZ
85251
US
|
Assignee: |
Symbol Technologies, Inc.
|
Family ID: |
38172638 |
Appl. No.: |
11/303137 |
Filed: |
December 16, 2005 |
Current U.S.
Class: |
312/7.1 ;
312/352 |
Current CPC
Class: |
H05K 5/0217
20130101 |
Class at
Publication: |
312/007.1 ;
312/352 |
International
Class: |
A47B 81/06 20060101
A47B081/06 |
Claims
1. A housing for protecting a component in a mobile device, said
housing comprising: a first structure comprising a first material,
wherein said first material is an elastomer; a second structure
comprising a second material and bonded to said first structure,
wherein said second material is a high-stiffness plastic, and
wherein the component is secured to said second structure.
2. The housing of claim 1, wherein said second structure is bonded
to said first structure via a chemical bond.
3. The housing of claim 1, wherein said high-stiffness plastic
comprises a long glass fiber filled thermoplastic.
4. The housing of claim 1, wherein said first material comprises a
thermoplastic elastomer.
5. The housing of claim 1, wherein said first material has a room
temperature flexural modulus that is greater than approximately 20
MPa.
6. The housing of claim 1, wherein said second material has a room
temperature flexural modulus that is greater than approximately 7
GPa.
7. The housing of claim 1, wherein said second material has an room
temperature notched Izod impact resistance that is greater than
approximately 350 J/m.
8. The housing of claim 1, wherein said first structure is located
at a corner of the housing.
9. The housing of claim 8, wherein said first structure is located
at all corners of said housing.
10. The housing of claim 1, wherein the housing has a first end, a
center, and a second end; wherein said first structure is located
at said first end and said second end; and wherein said second
structure is located at said center.
11. The housing of claim 1, wherein the housing has a projecting
handle, a main body, and a hinge, wherein said first structure is
located at said handle and said main body, and wherein said second
structure is located at said hinge.
12. The housing of claim 1, wherein said component is selected from
the group consisting of a liquid crystal display, a keyboard, and a
printed circuit board.
13. The housing of claim 1, wherein said first structure is located
in a region of the housing capable of tolerating deflection, and
wherein said second structure is located in a region of the housing
not capable of tolerating deflection.
14. A method for forming a rugged mobile device housing for
protecting a component, said method comprising the steps of:
identifying a first region of the mobile device housing capable of
tolerating deflection; identifying a second region of the mobile
device housing not capable of tolerating deflection; forming, using
an elastomer, a first structure of a first material in said first
region; forming, using a high-stiffness plastic, a second structure
of a second material in said second region; securing the component
to the second structure.
15. The method of claim 14, wherein said high-stiffness plastic
comprises a long glass fiber filled thermoplastic.
16. The method of claim 14, wherein said first material comprises a
thermoplastic elastomer.
17. The method of claim 14, wherein said first material has a room
temperature flexural modulus that is greater than approximately 20
MPa.
18. The method of claim 14, wherein said second material has a room
temperature flexural modulus that is greater than approximately 7
GPa.
19. The method of claim 14, wherein said second material has a room
temperature notched Izod impact resistance that is greater than
approximately 350 J/m.
20. A rugged mobile device comprising: a housing, said housing
comprising: a first structure comprising a first material, wherein
said first material is a high-stiffness elastomer, and wherein said
first structure is located in a region of said housing capable of
withstanding deflection; a second structure comprising a second
material and bonded to said first structure, wherein said second
material is a long glass fiber filled thermoplastic, and a liquid
crystal display secured to said second structure.
21. The mobile device of claim 20, wherein said housing includes a
plurality of corners, wherein said first structure corresponds to
said corners of said housing, and said second structure corresponds
to the center of said housing.
22. The mobile device of claim 20, wherein the first structure
corresponds to the center of the housing, and the second structure
corresponds to a first and second end of said housing.
Description
TECHNICAL FIELD
[0001] The present invention relates generally to mobile device
housings and, more particularly, to a rugged mobile device housing
elastically tailored to the application and incorporating multiple
materials.
BACKGROUND
[0002] Mobile devices such as cellular phones, personal data
assistants (PDAs), and the like often incorporate components that
are susceptible to shock damage incurred during an impact event.
Such components include, for example, liquid crystal displays
(LCDs), keyboards, printed circuit boards (PCBs), and other
structures prone to breaking under moderate stress.
[0003] Conventional housings aimed at addressing this problem in
mobile devices often incorporate a stiff frame (e.g., a die-cast
magnesium frame), which provides internal structure and thereby
prevents large deflections. Such frames, however, take up a
significant amount of space and add yet another costly component to
the system.
[0004] In order to accommodate sudden shock, conventional housings
also typically include a material such as a thermoplastic elastomer
that has a low modulus of elasticity and which acts as a shock
absorber. The use of such elastomers, however, often requires
additional internal components or over-molded, wear-resistant
plastics on the outside of the device housing.
[0005] Accordingly, it is desirable to provide a rugged mobile
device housing able to withstand the shock and large deflections
resulting from an impact event.
BRIEF SUMMARY
[0006] In accordance with the present invention, a rugged mobile
device housing for protecting a component (e.g., a liquid crystal
display, a keyboard, a printed circuit board, or the like) includes
one or more first structures comprising a first material provided
in a region of the housing capable of withstanding deflection,
wherein the first material is an elastomer, and one or more second
structures bonded to the first structure, wherein the second
structure is a high-stiffness, high-impact-resistance plastic. The
elasticity of the housing is thereby tailored by combining sections
made from a stiff plastic (where deflection needs to be minimized)
with adjacent sections made from a stiff elastomer (where shock
absorption is desired and large deflections can be tolerated). Such
tailored elasticity is of particular utility in mobile computing
devices with large displays where a small form factor and rugged
design is desired.
[0007] In one embodiment, the first material is a high-stiffness
elastomer and the second material is a long glass fiber filled
thermoplastic (or "LGF" plastic). In one embodiment, the first
structure is located at a corner of the housing and the second
structure is located in the middle of the housing. In another
embodiment, the first structure is located in the center of the
housing and the second structures are located at the ends. In yet
another embodiment, a projecting handle and hinge are provided,
where the first structure is located at the handle and the second
structure is located at the hinge.
BRIEF DESCRIPTION OF THE DRAWINGS
[0008] A more complete understanding of the present invention may
be derived by referring to the detailed description and claims when
considered in conjunction with the following figures, wherein like
reference numbers refer to similar elements throughout the
figures.
[0009] FIG. 1 is an isometric overview of a mobile device housing
in accordance with one embodiment of the present invention;
[0010] FIG. 2 is a side view illustration of the mobile device
housing of FIG. 1 during an impact event;
[0011] FIG. 3 is a cross-sectional view of a mobile device housing
in accordance with the embodiment of FIG. 1;
[0012] FIG. 4 is an isometric overview of a mobile device housing
in accordance with another embodiment of the present invention;
[0013] FIG. 5 is a side view illustration of the mobile device
housing of FIG. 4 during an impact event;
[0014] FIG. 6 is a cross-sectional view of a mobile device housing
in accordance with the embodiment of FIG. 4
[0015] FIG. 7 is an isometric overview of a mobile device housing
in accordance with one embodiment of the present invention;
[0016] FIG. 8 is a side view illustration of the mobile device
housing of FIG. 7 during an impact event; and
[0017] FIG. 9 is a cross-sectional view of a mobile device housing
in accordance with the embodiment of FIG. 7.
DETAILED DESCRIPTION
[0018] The following detailed description is merely illustrative in
nature and is not intended to limit the invention or the
application and uses of the invention. Furthermore, there is no
intention to be bound by any expressed or implied theory presented
in the preceding -technical field, background, brief summary or the
following detailed description.
[0019] In general, a rugged mobile device housing in accordance
with the present invention employs one material such as a
high-stiffness elastomer in a region of the housing capable of
withstanding deflection, and a second material such as a
high-stiffness plastic (e.g., a long glass fiber filled
thermoplastic, or "LGF" plastic) in areas requiring high rigidity
and/or impact resistance. A number of example structures are
presented below; however, the present invention is not so limited,
may be employed in wide array of housing designs.
[0020] In accordance with one embodiment, a housing includes a
first structure comprising a first elastomeric material and a
second structure comprising a second material bonded to the first
structure, wherein the second material is a high-stiffness plastic,
and wherein a component to be protected is secured to the second
structure.
[0021] In this regard, "stiffness" relates to the ability of the
material to resist deformation (strain) under an applied load
(stress). Stiffness is usually characterized by modulus of
elasticity, or "Young's modulus." Impact strength relates to a
material's ability to withstand shock loading, and may be measured
using conventional testing, such as the Izod impact test. (ASTM D
256) or Charpy impact test (DIN 53453).
[0022] An elastomer is an amorphous, vulcanisate polymer that can
withstand significant elastic deformation. As such, the stiffness
of an elastomer is typically lower than that of other plastics.
Nevertheless, in accordance with one embodiment of the present
invention, the first material (used for the first structures
located in areas that can withstand deformation) comprises a
high-stiffness thermoplastic elastomer, e.g., a TPU (thermoplastic
polyurethane) or TPEE (thermoplastic polyester elastomer). In
general, the term "high-stiffness elastomer" as used herein refers
to an elastomer with a room temperature flexural modulus (ASTM D
790) greater than about 20.0 MPa or with a Durometer (ASTM D 2240)
of greater than about 70 Shore A. Suitable high-stiffness
elastomers include, for example, various Arnitel elastomers
manufactured by DSM Engineering Plastics, Hytrel elastomers
manufactured by Dupont, Texin elastomers manufactured by Bayer, and
Estane elastomers manufactured by Noveon.
[0023] The term "high-stiffness plastic" as used herein with
respect to the second material refers to a plastic with a room
temperature flexural modulus (ASTM D 790) of greater than about 7.0
GPa, preferably 10.0 GPa or higher. The term "high-impact" as used
herein refers to a material with a room temperature notched Izod
impact resistance (ASTM D 256) greater than about 350 J/m.
[0024] In one embodiment, the second material comprises a long
glass fiber filled thermoplastic. Long glass fiber filled
thermoplastics (or "LGF plastics") are thermoplastic materials
reinforced by fibers that are substantially longer than the "short"
fibers traditionally used for reinforcement. While traditional
short fibers might have a length of about 1.0 mm, long fibers have
a length on the order of 10 mm, depending upon the application and
desired properties. The use of long fibers has a number of
advantageous mechanical properties--e.g., increased stiffness
(approximately 10 GPa) and increased impact resistant
(approximately 240 J/m, notched Izod). In this way, the
high-stiffness plastic can play the role of a traditional magnesium
frame. Suitable LGF plastics include, for example, Celstran long
fiber reinforced thermoplastics manufactured by Ticona.
[0025] As mentioned above, the first structures are suitably fixed
with respect to the second structures. The two materials may be
bonded in any suitable fashion, including mechanical attachment,
chemical bonding, adhesive bonding, or in any other manner. In one
embodiment, the materials are bonded via a chemical bond during a
molding process ("overmolding"). For example, in one embodiment,
the first material is a high-stiffness elastomer and the second
material is a LGF plastic, and these materials are chemically
bonded during the injection molding process. Injection molding
technology is well known in the art, and therefore the details of
such processes need not be described herein. The component to be
protected may be attached or incorporated into the housing using
any convenient method, including various adhesives, mechanical
fasteners, and the like.
[0026] Having thus given an overview of the present invention,
various exemplary housing designs will now be described in
conjunction with FIGS. 1-9. It will be appreciated, however, that
these embodiments are merely given as examples, and are not
intended to limit the range of housing designs comprehended by the
invention. Furthermore, it will be understood that additional
materials (in addition to the first and second material) will
typically be incorporated into the housing as well.
[0027] FIG. 1 presents one embodiment of a housing 100 for
protecting a component 102. In general, housing 100 includes
structures 104 comprising the first material at one or more corners
of the housing, with structures 106 framing component 102 (and
bonded to structures 104) to provide central rigidity. As shown in
FIG. 2, during a typical impact event, one of the corners 204 may
impact a surface 202, leading to elastic deformation of corner 204.
This impact event would likely lead to one or more subsequent
impact events of decreasing amplitude as the housing 100 comes to
rest. The deformation of structures 104 effectively absorbs the
impact energy, while centrally-located structures 106 encompassing
component 102 provide the desired rigidity. As shown in FIG. 3,
structures 104 are suitably bonded to structures 106 (e.g., via a
chemical bond), thus forming, in the illustrated embodiment, a
relatively stiff skeleton with flexible corners consisting of the
first material.
[0028] FIG. 4 presents a second embodiment of a housing 100 for
protecting a component 102. In this embodiment, a structure 104
comprising the first material is provided in a middle region of
housing 100, while structures 106 are provided on one or more ends
of the housing. In the illustrated embodiment, corresponding
roughly to a conventional cellular phone configuration, a keyboard
402 is illustrated within one of the structures 106, and a
component 102 (e.g., a display) is illustrated within the opposite
structure 106. As shown in FIG. 5, a typical impact event would
involve collision of the high-stiffness plastic structure 206 at a
corner or edge 204, allowing central structure 104 to absorb the
energy through elastic deformation. FIG. 6 depicts chemical bonding
of stiff skeletal structures 106 (second material) to the sides of
flexible center 104 (first material).
[0029] FIG. 7 presents a third embodiment of a housing 100 that
includes a projecting handle 702, a main body 704 (comprising one
or more regions 106), and a hinge region defined by structure 104.
Such an embodiment might correspond, for example, to a barcode
scanner or other device that typically has a handle. Referring to
FIG. 8, during a typical impact event, projecting handle 702 will
impact at a point 204, allowing structure 104 to elastically
deform, while structures 106 protect the attached components. As
shown in FIG. 9, structures 106 form a stiff skeleton bonded to
structure 104.
[0030] In general, the design principles set forth above may be
used to develop ruggedized housings for any suitable application,
while obviating the need for additional stiff internal structures.
The first step, once the overall size and shape of the desired
housing is determined, involves identifying which area or areas of
the housing are capable of tolerating deflection (e.g., bending,
twisting, etc.), and which cannot. This will depend, for example,
on the projected location of components that cannot safely
withstand bending stress (e.g., LCD displays, brittle components,
circuit boards, keyboards, and the like). Next, it is determined
which areas of the housing require a high impact resistance. This
will depend, not only on the placement of components, but also the
location of the regions that will be allowed to deflect during an
impact event. Finally, the first and second materials (e.g., the
high-stiffness elastomer and high-stiffness LGF plastic,
respectively) are strategically incorporated such that the housing
taken as a whole can withstand the desired level of impact while
protecting certain target components, which will generally be
secured to a high-stiffness LGF plastic structure.
[0031] While at least one example embodiment has been presented in
the foregoing detailed description, it should be appreciated that a
vast number of variations exist. It should also be appreciated that
the example embodiment or embodiments described herein are not
intended to limit the scope, applicability, or configuration of the
invention in any way. Rather, the foregoing detailed description
will provide those skilled in the art with a convenient road map
for implementing the described embodiment or embodiments. It should
be understood that various changes can be made in the function and
arrangement of elements without departing from the scope of the
invention as set forth in the appended claims and the legal
equivalents thereof.
* * * * *