Circuitry protection device

An electronic circuitry protection device is disclosed. The device comprises a flexible, plastic, water-proof enclosure formed to envelop the electronic circuitry of a portable or hand-held cellular telephone. The protected circuitry is mounted within the telephone housing itself, and the design of the enclosure accommodates the fasteners used for mounting and connections to external devices without compromising its protective ability.

BACKGROUND OF THE INVENTION 
1. Technical Field of the Invention 
The present invention is directed to a device for the protection of 
electronic circuitry, and specifically to the protection of the internal 
circuitry of a portable or hand-held telephone from water damage. 
2. Description of Related Art 
Portable cellular phones are becoming increasing popular. As advances in 
cellular technology make their use easier and more affordable, cellular 
users avail themselves of their portable telephones for both business and 
personal use in a variety of environments. Some of these environments 
present conditions that may inadvertently result in damage to electronic 
equipment. 
In particular, the portability of cellular phones has led to increased use 
near open water such as swimming pools, lakes, and rivers. Since the 
telephones are often used out-of-doors, calls are commonly made and 
received in the vicinity of fountains, tanks, and even large puddles. The 
hand-held units are often self-contained and not attached to the user or 
some larger fixture in any way. If dropped or tossed, the telephone could 
easily come into contact with the water, which may quickly incapacitate or 
damage the internal electronic circuitry. Similar damage could result from 
spilled or running liquids, such as beverages on a conference table, or 
from rainfall. 
Existing protection for cellular telephones from water damage includes the 
use of water-tight carrying cases. These are often quite effective, but 
the phone must be removed from the carrying case for use; and such 
protection requires that the user anticipate the possible encounter with a 
water hazard and have the case available and employed. In addition, the 
seam between the two halves of the telephone housing can be sealed, but 
this method can be expensive, aesthetically undesirable, and only 
partially effective. Strategically placing gaskets or cloths in certain 
areas, such as the telephone's microphone opening, provide a barrier at 
that point, but not overall protection. The need exists for a form of 
electronic circuitry protection that protects substantially all of the 
internal circuitry, protects while the telephone is in use, requires no 
affirmative action by the user in order to be employed, and can be 
efficiently incorporated into the telephone's construction. 
The invention of the present disclosure provides just such passive and 
continuous protection in a manner that does not add unduly to the cost of 
the unit and allows for easy replacement of the protective elements, if 
necessary. 
SUMMARY OF THE INVENTION 
The present invention is directed to a protective bag-like enclosure for 
telephone electronic circuitry, generally made of flexible plastic 
material, that in use is itself disposed inside the housing, or frame of 
the telephone. Ideally, little or no modification of the telephone housing 
is required in order to facilitate installation of the enclosure. The 
enclosure can be installed at the time of unit assembly or, with minor 
disassembly, incorporated into an existing phone. The enclosure can have 
any shape, but preferably has one open end or opening large enough to 
receive the circuity that during telephone assembly will be sealed either 
totally or around a connector. Openings in the enclosure for other 
electrical connections and for mounting fasteners are also sealed in such 
a way that invasion of water and other liquids through the openings is 
resisted or prevented. The design of the enclosure is such that the 
readability of visual displays and operability of the keypad is not 
materially affected. To prevent wear and to enhance water-resistance, 
portions of the enclosure are reinforced. 
A more complete appreciation of the present invention and the scope thereof 
can be obtained from the accompanying drawings which are briefly 
summarized below, the following detailed description of the 
presently-preferred embodiments of the invention, and the appended claims.

DETAILED DESCRIPTION OF THE PRESENT INVENTION 
FIG. 1A illustrates the enclosure 1 of the invention separate from the 
telephone. The enclosure 1 is large enough to envelop the telephone 
circuitry to be protected and small enough to permit the enveloped 
circuitry to be installed inside the telephone housing. Preferably, the 
enclosure 1 is a bag-like structure made of a flexible plastic waterproof 
material. The material may be thermally contractive, but should not be 
electrically conductive unless a non-conductive material can be inserted 
between the circuitry and the enclosure. In this disclosure, the terms 
"waterproof" and "water-resistant" are used interchangeably to connote a 
material through which water or other liquids may not pass easily, if at 
all. Although "water" is explicitly discussed, it is understood that the 
invention is intended to resist penetration by most liquids. 
The optimum shape for the enclosure will depend on the design of the 
telephone in which it will be used and on manufacturing considerations. 
The preferred enclosure 1 comprises an integral top side 2, bottom side 3, 
closed end 4, and open end 5. Open end 5 permits the printed circuit board 
(not shown in FIG. 1A) to be easily inserted and positioned, after which 
enclosure 1 is sealed by any of a number of methods, some of which are 
discussed below. Top side 2 comprises an integral viewing portion 6 to 
provide an undistorted view of the telephone's liquid crystal display 12 
(not shown in FIG. 1A). The material of viewing portion 6 is stiff enough 
to remain free from any wrinkles that might otherwise form in the 
relatively more flexible material of the enclosure 1. Top side 2 also 
comprises an integral reinforced portion 7 to be positioned beneath the 
telephone keypad 41 (not shown in FIG. 1A) to provide greater resistance 
to wear. Other portions of the enclosure may also be reinforced if 
desired, such as might be the case in the area proximate to an opening. 
Reinforced portions can be provided by adding material, or by locally 
varying the material's composition, for example by using additives to 
produce a relatively more wear-resistant section. Of course, if the 
enclosure's material is deemed sufficiently wear-resistant, reinforced 
portion 7 is unnecessary. When mounting fasteners are to be used, the 
preferred enclosure 1 is provided with a plurality of fastener openings 8, 
as more fully described below in relation to FIGS. 3A, 3B and 3C. 
Alternatively, the fastener openings 8 are created when the fastener is 
installed, in which case it is preferred that enclosure 1 be reinforced in 
the potential opening area or areas. Antenna opening 25 in closed end 4 
accommodates the installation of an external antenna. 
FIG. 1B illustrates the positioning of the enclosure 1 inside the housing 
11 of a conventional cellular telephone. Although a cellular telephone is 
depicted, the present invention can be used in any type of hand-held, 
portable phone, such as one in communication with the base station of a 
conventional home-telephone system. Opening 25 in closed end 4 is aligned 
with antenna body 21 so that the antenna can be connected to a connector 
on the printed circuit board 10 (as illustrated in FIG. 2). Viewing 
portion 6 is aligned with a display window 13 of housing 11 so that the 
user can view the telephone's LCD display 12, which lies inside enclosure 
1. 
Reinforced portion 7 is positioned under keypad 41. Open end 5 is shown 
closed about system connector 50 by band 51. 
Referring to FIG. 2, the closed end 4 of enclosure 1 has an opening 25 just 
large enough for insertion therethrough of the telephone antenna lead 20. 
When assembled, this opening aligns with the antenna connector 22 of the 
printed circuit board 10 so that an antenna may be installed. The opening 
25 is preferably smaller in diameter than the antenna body 21 so that when 
it is seated properly the closed end 4 of enclosure 1 is sealed against 
antenna connector 22 and intrusion by liquids though the opening 25 is 
inhibited. Further protection against liquid penetration through opening 
25 can be obtained by installing a gasket 26 between the antenna body 21 
and the closed end 4 of the enclosure 1. To help ensure proper 
positioning, the gasket could be attached to either antenna body 21 or 
closed end 4 using a suitable adhesive. In locations where separate 
gaskets, such as gasket 26, are used, they can be conventional O-ring 
gaskets, washers or suitably-formed pieces of gasket material placed on or 
adhered to the enclosure 1 at the location where the opening is to be 
formed. Alternatively, reinforcing closed end 4 of the enclosure 1 at the 
periphery of opening 25 will provide additional protection against liquid 
penetration, either alone or in combination with gasket 26. FIG. 2 also 
shows top side 2 of enclosure 1 positioned between housing 11 and 
telephone speaker 14. 
Turning to FIGS. 3A and 3B, one or more mounting screws 31 or other 
suitable fasteners may be used to secure the printed circuit board 10 
within the telephone housing 11, or to hold together sections of the 
telephone housing, or to do both. To avoid leakage when mounting fasteners 
are used, fastener openings 8 are preferably pre-formed in enclosure 1. In 
this embodiment, two fastener openings 8 are aligned with each other and 
with an opening in the printed circuit board 10, which is being held in 
place by a mounting screw 31. Generally, it is expected that the head of 
screw 31 on one side and the telephone housing 11 on the other will seal 
the fastener openings 8 and resist leakage. For further protection, 
however, mounting screw gaskets 32 may be used, as shown in FIG. 3B, or 
the periphery of the fastener openings 8 may be reinforced, or both. 
FIG. 3C shows yet another mounting fastener configuration. In the 
embodiment of FIG. 3C, mounting screw 31 protrudes through telephone 
housing 11 to act as a conductor between an external battery (not shown) 
and a conductor (not shown) of the printed circuit board 10. In this 
embodiment, one fastener opening 8 is sealed by mounting screw gasket 32 
pressing enclosure 1 against printed circuit board 10. Alternately, a 
second gasket could be used, or the openings 8 could both be closed by 
appropriately formed portions of housing 11. Whenever portions of the 
housing 11 are employed to seal an opening, the portions of housing 11 
that contact the enclosure 1 may be treated, coated, or covered with a 
resilient or adhesive material to enhance water-resistance. 
Turning to FIG. 4, keypad 41 is disposed outside reinforced portion 7 of 
enclosure 1. A polydome 42 is positioned on the printed circuit board 10 
directly below keypad 41 and inside enclosure 1. Each individual dome 
switch 44 of polydome 42 is aligned with a key of keypad 41 and has 
underneath it a conductive pill 43 that corresponds to a switch (not 
shown) on printed circuit board 10. The switch is therefore operated 
whenever the corresponding switch dome 44 is depressed and released. 
Downward force on the key is easily transmitted to the dome switch 44 
through the reinforced portion 7 of enclosure 1. 
FIG. 5A provides a cross-sectional view illustrating an embodiment with 
open end 5 of enclosure 1 closed against the system connector 50 by system 
connector band 51. Band 51 is preferably made of elastic material, but can 
also take the form of a non-elastic tie, cord, clamp, or equivalent 
structure. Preferably, for any existing telephone design it is possible to 
fabricate an appropriately-sized system connector band 51 that will of 
itself provide water-resistant closure. Some modification of the shape of 
the system connector 50, printed circuit board 10, or housing 11, however, 
may be necessary, or at least helpful to providing or enhancing 
water-resistance. Alternative methods of closing open end 5 may also be 
used. Depending on the telephone's design, it may be preferable to close 
open end 5 around the printed circuit board 10 itself, or some other 
component, or to provide an intermediate seating surface against which to 
close open end 5 of enclosure 1. 
Open end 5 can also be adhesively attached to the printed circuit board 10 
or the system connector 50. If no system connector is used, the enclosure 
1 can simply be closed and heat-sealed. An adhesive seal could also be 
employed, as could a mechanical one, for example, using a tie, clamp or 
appropriately formed portions of the housing 11 to seal the enclosure 1 
shut. 
It will also be recognized that any suitable shape for the enclosure 1 may 
be used, and that instead of providing an open end 5, any opening of 
sufficient size will enable the printed circuit board 10 to be placed 
inside the enclosure. Alternatively, enclosure 1 could be formed with the 
printed circuit board 10 inside it and any openings or open sides closed 
or sealed appropriately. For added protection or convenience, any of the 
methods described above can also be used in combination with each other. 
Also shown in FIG. 5A is the use of a system connector plug 52, which can 
be inserted to provide further protection against penetration by liquid 
when the system connector is not in use. Preferably, the system connector 
forms a groove 53 into which a matching protrusion 54 on plug 52 can be 
installed. The plug 52 of FIG. 5A is shown as a separate component, but it 
could also be connected to the telephone housing 11 by a hinge, cord, or 
similar device. 
FIG. 5B provides an end view of the embodiment shown in FIG. 5A. In this 
embodiment, portions of housing 11 are formed so as to secure band 51 in 
place when the telephone is assembled. 
FIG. 5C illustrates an alternative cooperation between the printed circuit 
board 10, the system connector 50, the system connector band 51 and the 
telephone housing 11 to effectively close open end 5 of enclosure 1, as 
viewed cross-sectionally from the end of the telephone. In this 
embodiment, the effectiveness of the seal is enhanced by pressure from 
appropriately formed portions of the assembled telephone housing 11. 
The previous description is of a preferred embodiment for implementing the 
scope of the invention and should not necessarily be limited by this 
description. The scope of the present invention is instead defined by the 
following claims.