Patent Publication Number: US-9843355-B2

Title: Apparatus and method for venting and sealing a portable communication device

Description:
FIELD OF THE INVENTION 
     The present invention relates generally to venting and sealing assemblies and more particularly to venting and sealing a portable communication device. 
     BACKGROUND 
     Today&#39;s portable communication devices are challenged to incorporate an increasing number of features into a small form factor. Portable communication devices, such as portable radio products utilized in the public safety market, are further challenged by having to operate under severe environmental conditions where maintaining appropriate venting and sealing of the product is imperative to proper operation of the radio. The venting and sealing of the ruggedized product needs to be operational at predetermined pressure ratings not typically associated with off-the shelf consumer type products. For example, ever-increasing water submersion ratings for ruggedized products present venting and sealing challenges. 
     Many of today&#39;s typical venting approaches have drawbacks making them unsuitable for the portable radio public safety environment. For example, air hole structures which are completely passive for venting offer no sealing capability and thus no protection in wet environments. Products which utilize membranes that must be removed for test purposes face issues with improper re-alignment and large venting structures take up too much real estate and face potential leak issues. 
     Accordingly, it would be desirable to have an improved venting and sealing assembly. An improved venting and sealing assembly that could address the above aforementioned problems would be of particular benefit for incorporation into a portable communication device utilized in the public safety environment. 
    
    
     
       BRIEF DESCRIPTION OF THE FIGURES 
       The accompanying figures where like reference numerals refer to identical or functionally similar elements throughout the separate views and which together with the detailed description below are incorporated in and form part of the specification, serve to further illustrate various embodiments and to explain various principles and advantages all in accordance with the present invention. 
         FIG. 1A  is a partial cutaway view of a venting and sealing assembly having an open vent path in accordance with an embodiment. 
         FIG. 1B  is a partial cutaway view of the venting and sealing assembly of  FIG. 1B  having a sealed vent path closed in accordance with an embodiment. 
         FIG. 2  is a partial cutaway isometric view of a portable radio incorporating a venting and sealing assembly in accordance with an embodiment. 
         FIG. 3  is a partial cutaway view of a venting and sealing assembly having a vent path in accordance with another embodiment. 
         FIG. 4  is a partial cutaway view of a venting and sealing assembly having a vent path in accordance with another embodiment. 
     
    
    
     Skilled artisans will appreciate that elements in the figures are illustrated for simplicity and clarity and have not necessarily been drawn to scale. For example, the dimensions of some of the elements in the figures may be exaggerated relative to other elements to help to improve understanding of embodiments of the present invention. 
     DETAILED DESCRIPTION 
     Before describing in detail embodiments that are in accordance with the present invention, it should be observed that the embodiments reside primarily in a venting and sealing assembly. The venting and sealing assembly can be incorporated into a communication device, such as a portable radio or remote speaker microphone, and is particularly well suited to portable communication devices intended for the public safety environment. 
     Briefly, a housing enclosure of the device provides an internal walled aperture providing a vent path formed therein passing from an interior of the housing to an exterior of the housing. A passive pressure equalization vent, formed of a breathable membrane, is mounted to an active sealing valve mechanism. The active sealing valve mechanism comprises a moveable substrate, which may be formed of a flexible or rigid material, which automatically seals to the internal walled aperture or vent path to create a pressure sensitive barrier in response to predetermined changes in pressure. An internal sealing rib surface limits travel of the moveable substrate within the internal walled aperture. The venting and sealing assembly takes up little space making it well suited for devices having limited space constraints. 
     Accordingly, the components have been represented where appropriate by conventional symbols in the drawings, showing only those specific details that are pertinent to understanding the embodiments of the present invention so as not to obscure the disclosure with details that will be readily apparent to those of ordinary skill in the art having the benefit of the description herein. 
     In this document, relational terms such as first and second, top and bottom, and the like may be used solely to distinguish one entity or action from another entity or action without necessarily requiring or implying any actual such relationship or order between such entities or actions. The terms “comprises,” “comprising,” or any other variation thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements does not include only those elements but may include other elements not expressly listed or inherent to such process, method, article, or apparatus. An element preceded by “comprises . . . a” does not, without more constraints, preclude the existence of additional identical elements in the process, method, article, or apparatus that comprises the element. 
       FIGS. 1A and 1B  show a partial cutaway view of a venting and sealing assembly  100  in accordance with an embodiment.  FIG. 1A  shows an open vent path  102  in accordance with an embodiment, while  FIG. 1B  shows a sealed vent path  104  being established in accordance with an embodiment. Assembly  100  comprises a housing enclosure  106  having a walled aperture  108  with a bottom surface  110  and an offset through-hole  112  passing therethrough. The assembly  100  further comprises a flexible substrate  114  having a vent hole  116 , the flexible substrate being coupled to the housing enclosure  106  across the walled aperture  108 . In accordance with an embodiment, the vent hole  116  of the flexible substrate  114  is offset from the offset through-hole  112  of the bottom surface  110  of the walled aperture  108 . The flexible substrate  114  may be formed of a silicone rubber sheet, or suitable air impermeable and water impermeable material that allows for flexible vertical movement. In the embodiment of  FIGS. 1A and 1B , a closed-loop sealing rib  124  is integrated around the vent hole  116  of the flexible substrate  114 . 
     In accordance with an embodiment, a breathable membrane  118  is coupled across the vent hole  116  of the flexible substrate  114 . The breathable membrane  118  may be formed of material having air breathable but water restrictive properties, such as expanded Polytetrafluoroethylene (PTFE) material, for example expanded TEFLON, or other appropriate material having air breathable and water restrictive properties. For example, membranes made of air-permeable and water-impermeable material, such as Gore-Tex® material available from W. L Gore, are suitable. For the purposes of this application, the breathable membrane  118  is considered to be air-permeable and water-impermeable. The breathable membrane  118  is adhesively coupled to the flexible substrate  114 , such that membrane covers the vent hole  116  providing a barrier to water while allowing air to pass through. 
     In accordance with an embodiment, a rigid plate  120 , having an opening  122 , is coupled to the breathable membrane  118 , such that the opening  122  of the rigid plate  120  is aligned with the vent hole  116  of the flexible substrate  114 . The rigid plate  120  is formed of a stiffener material such as rigid plastic, for example stamped or molded plastic, to provide sufficient stiffness to back up the flexible substrate  114  over a closed-loop sealing rib  124 . 
     During normal operation, the vent path  102  is formed through the offset through-hole  112  of the housing enclosure  106 , the walled aperture  108  of housing enclosure  106 , the vent hole  116  of the flexible substrate  114 , and the breathable membrane  118  coupled across the vent hole  116  of the flexible substrate  114  and the opening  122  of the rigid plate  120 . The breathable membrane  118  coupled across the vent hole  116  behaves as a passive pressure equalization vent. 
     In accordance with an embodiment, the rigid plate  120  provides an external rigid surface area that is larger than the internal sealing area created by the closed-loop sealing rib  124  thereby providing adequate sealed backup. The rigid plate  120  provides gain in the valve sealing pressure to securely isolate the breathable membrane  118  or in other words isolates the passive pressure equalization vent. 
     In accordance with other embodiments, the closed-loop sealing rib  124  may formed upon at least one of: the flexible substrate  114 , around the vent hole  116  and/or upon the bottom surface  110  of the walled aperture  108  of the housing enclosure  106 . In the embodiment of  FIGS. 1A and 1B , the closed-loop sealing rib  124  is a closed-loop compliant seal rib integrated around the vent hole  116  of the flexible substrate  114 . 
     In  FIG. 1B , the flexible substrate  114  having a compliant closed-loop sealing rib  124  integrated thereon is shown establishing a seal against the bottom surface  110  of walled aperture  108 . In this view, the flexible substrate  114  has collapsed in response to a predetermined change in pressure sensed through the breathable membrane  188  at vent hole  116 . The sealing shown in  FIG. 1B  isolates the breathable membrane  118 . The closed-loop sealing rib  124  limits travel of the flexible substrate  114 . In accordance with an embodiment, the flexible substrate  114  operates as an active sealing valve mechanism to form a waterproof barrier over the walled aperture  108  of the housing enclosure  106 . 
       FIG. 2  is a partial cutaway isometric view of a portable communication device, shown here as a portable radio  200 , incorporating a venting and sealing assembly formed in accordance with an embodiment. Portable radio  200  comprises a housing  206  having an interior walled aperture  208  through which a vent path  202  vents and seals from an interior  260  of the housing  206  to an exterior  250 . 
     In accordance with an embodiment, a moveable substrate  214  having a vent hole  216  operates as an active sealing valve mechanism. The moveable substrate  214  is mounted to the housing  206  such that the vent hole  216  opens into the interior walled aperture  208 . A passive pressure equalization vent, formed of a breathable membrane  218 , covers the vent hole  216  across the moveable substrate  214 . In accordance with the embodiment, the active sealing valve mechanism (moveable substrate  214 ) and passive equalization vent (breathable membrane  218 ) automatically seal to the interior walled aperture  208  to create a pressure sensitive barrier—in response to predetermined changes in pressure. 
     In  FIG. 2 , the moveable substrate  214  comprises a flexible substrate coupled to the housing  206 , wherein the internal sealing rib  224  is formed as part of an interior surface of a moveable substrate  214 . An internal sealing rib  224  limits travel of the moveable substrate  214  within the interior walled aperture  208 . 
     The internal sealing rib  224 , as will be shown in the embodiment of  FIG. 3 , may also be formed on a bottom sealing surface of the internal walled housing. In yet another alternative embodiment, which will be described later in conjunction with  FIG. 4 , the moveable substrate may comprise a rigid substrate coupled to the housing with flexure bellows, and the internal rib sealing surface comprises a flexible substrate with a compliant sealing rib forming a base of the walled aperture. 
     Accordingly, the outer moveable substrate may be formed of either a flexible material or a rigid material. The exterior moveable substrate of the various embodiments gets pulled into the housing aperture in response to predetermined changes in pressure thereby forming a seal with the closed loop sealing rib. The various embodiments provide for an active sealing valve mechanism and passive equalization vent which automatically seals to an internal walled aperture to create a pressure sensitive barrier. 
     Changes in pressure can be caused by a variety of factors such as, including but not limited to: moving from a warm environment to a cold environment; from a cold environment to a warm environment; inefficiencies of internal components RF and audio power amplifiers (PAs) causing the air sealed within the enclosure to be heated and expand; long duration, maximum rate free-fall of high altitude low opening (HALO); rapid climbing maneuvers in an un-pressurized helicopter; rapid environmental decompression (for example, a cabin airliner). 
     An advantage associated with the various embodiments is that the breathable membrane remains present both during factory testing of the venting and sealing assembly of the portable radio and after shipment of the portable radio, thereby eliminated any alignment issues associated with removal and replacement of a membrane for test purposes. 
       FIG. 3  is a partial cutaway view of a venting and sealing assembly  300  in accordance with another embodiment. Assembly  300  is similar to assembly  100  in that the assembly comprises housing enclosure  106  having a walled aperture  108  with bottom surface  110  and offset through-hole  112  passing therethrough. The assembly  300  further comprises flexible substrate  114  having vent hole  116 , the flexible substrate being coupled to the housing enclosure  106  across the walled aperture  108 . In accordance with the embodiment, the vent hole  116  of the flexible substrate  114  is offset from the offset through-hole  112  of the walled aperture&#39;s bottom surface  110 . The breathable membrane  118  is coupled across the vent hole  116  of the flexible substrate  114 . The rigid plate  120 , having opening  122 , is coupled to the breathable membrane  118 , such that the opening  122  of the rigid plate is aligned with the vent hole  116  of the flexible substrate  114 . 
     In accordance with this  FIG. 3  embodiment, assembly  300  comprises a closed-loop sealing rib  324  formed as a hard-stop closed loop sealing rib integrated as part of the bottom surface  110  of the walled aperture  108  of the housing enclosure  106 . 
     Similarly to assembly  100 , in assembly  300  the vent path is provided through the offset through-hole  112  of the housing enclosure  106 , the walled aperture  108  of housing enclosure  106 , the vent hole  116  of the flexible substrate  114 , the breathable membrane  118  coupled across the vent hole  116  of the flexible substrate  114  and the opening  122  of the rigid plate  120 . However, in accordance with the embodiment of  FIG. 3 , as the flexible substrate  114  collapses, under predetermined pressure, into the walled aperture  108  against the bottom surface  110 , the hard-stop closed-loop sealing rib  324  of the bottom surface  110  within the walled aperture  108  seals against the flexible substrate  114  thereby isolating the breathable membrane  118 . The closed-loop rib  324  limits travel of the flexible substrate  114 . The use of the hard-stop closed-loop sealing rib  324  on the stationary, bottom surface  110  for sealing purposes still results in an isolated breathable membrane  118 . 
     In another embodiment also shown in  FIG. 3 , closed-loop sealing rib  124  (shown in dashed lines) and closed-loop sealing rib  324  may located on opposite upper and lower interior surfaces and slightly offset from each other, for a dual rib approach if desired. Thus, the closed loop sealing rib can be incorporated on one or both of the interior surfaces (i.e. interior bottom surface  110  and/or interior of surface of flexible substrate  114 ). For example, a combination of a hard-stop closed-loop sealing rib  324  and a compliant closed-loop sealing rib  124  can be used. 
     In accordance with this alternative embodiment, as the flexible substrate  114  collapses, under predetermined pressure, into the walled aperture  108  against the bottom surface  110 , the closed-loop hard-stop sealing rib  324  seals against the flexible substrate  114  in conjunction with the compliant closed-loop sealing rib  124  sealing against the bottom surface  110  of walled aperture  108 , thereby isolating the breathable membrane  118 . The closed-loop sealing ribs  124  and  324  limit travel of the flexible substrate  114 , thereby protecting the substrate surfaces, while providing a seal. 
     The embodiments provided thus far provide for a venting and sealing assembly wherein the breathable membrane provides a passive pressure equalization vent mounted in series with the moveable substrate which operates as an active sealing valve mechanism. 
     In another alternative embodiment, shown in  FIG. 4 , a breathable membrane provides a passive pressure equalization vent to a moveable rigid substrate separated by a vent passage across from an interior stationary flexible substrate.  FIG. 4  is a partial cutaway view of a venting and sealing assembly  400  in accordance with this alternative embodiment. 
     Assembly  400  comprises a housing  406  having a moveable substrate portion, formed of a rigid material. The rigid material may be formed, for example, of the same or similar material to that as the housing  406 , such as a hard plastic or other water impermeable material. In accordance with this embodiment, flexure bellows  420  or other flexible interconnect means, enable movement of the rigid substrate portion relative to the housing  406  and will therefore be referred to as moveable rigid substrate  414 . A vent hole  416  is formed in the moveable rigid substrate  414  for venting between an interior  460  and an exterior  450  of the housing  406 . The exterior  450  of the housing  406  is sometimes referred to as the wet side of the radio, while the interior of the housing  406  is sometimes referred to as the dry side. 
     In accordance with this embodiment, a breathable membrane  418  is coupled across the vent hole  416  of the moveable rigid substrate  414 . The breathable membrane  418  is coupled across the vent hole  416  of the moveable rigid substrate  414  and adhesively coupled to the moveable rigid substrate  414  with an adhesive layer  417 . The adhesive layer  417  has a cut-out which aligns with the vent hole  416  of the moveable rigid substrate  414 . The adhesive layer  417 , may be a pressure sensitive adhesive (PSA), such as a very high bond (VHB) adhesive or other suitable adhesive. 
     An internal rib sealing surface is provided by a flexible substrate  410  having a compliant sealing rib  424  formed thereon. The flexible substrate  410  is stationarily coupled within a walled aperture  408  formed within the housing  406 . In accordance with the embodiment, the vent hole  416  of the moveable rigid substrate  414 , covered by breathable membrane  418  opens into the walled aperture  408  across from the flexible substrate. The closed-loop sealing rib  424  is aligned and beneath the moveable rigid substrate  414  around the breathable membrane  418 . In accordance with an embodiment, the moveable rigid substrate  414  (exterior movable surface) has a wider surface area than the flexible substrate  410  that provides the internal rib sealing surface (interior sealing surface). The use of the moveable rigid substrate  414  on the outer surface provides the stiffness backing in a similar manner to that of the rigid plate  120  in the previous embodiments, while the flexible substrate  410  is located in the interior side  460 . 
     In response to predetermined changes in pressure being sensed between the interior  460  and the exterior  450  at the vent hole  416  by the restrictive properties of the breathable membrane  418 , the moveable rigid substrate  414  is pulled into the walled aperture  408  against the closed-loop sealing rib  424  of the flexible substrate  410  thereby isolating the breathable membrane  418 . 
     In normal use mode, the vent path  402  is formed between the exterior  450 , the breathable membrane  418  covering the vent hole  416  of the moveable rigid substrate  414 , the walled aperture  408 , through the offset vent-hole  412  into interior  460 . In sealing mode, the vent path  402  becomes sealed in response to the predetermined pressure (pressure mode) pulling the breathable membrane  418  coupled across the vent hole  416  of the moveable rigid substrate  414  across the closed-loop sealing rib  424  of the flexible substrate  410 . Thus, venting and sealing have been provided by the embodiment of  FIG. 4 . 
     In accordance with an embodiment, the vent hole  416  of the moveable rigid substrate  414  may extend into a drainage cone  428  formed into the moveable rigid substrate for water drainage. Alternatively, the moveable rigid substrate  414  may extend straight out the vent hole  416 , similarly to the opening  122  of the rigid plate  120  of the other previously described embodiments. 
     Accordingly, there has been provided, a substrate (flexible or rigid) that moves against a bottom surface of a walled aperture of a housing and seals using a closed loop sealing rib thereby isolating a breathable membrane coupled to the moveable substrate. The internal sealing rib limits travel of the moveable substrate within the interior walled aperture for sealing a vent passage. 
     The closed loop sealing rib may be formed on the interior surface of one or both of: a moveable flexible substrate  114 , such as was shown by sealing rib  124 , and an interior stationary bottom surface  110 , such as was shown by sealing rib  324 . The closed loop sealing rib  424  may also be formed on an interior stationary bottom flexible substrate  410 . 
     For a normal use case, in each of the embodiments, force and deflection characteristics of the moveable outer substrate (flexible  114 ,  214  or rigid  414  outer substrate) and positioning of the one or more interior closed-loop ribs ( 124 ,  224 ,  324 ,  424 ) provide for the valve mechanism. For a pressure use case: the movable substrate (flexible  114 ,  214  or rigid  414 ) collapses into the walled aperture such that the closed loop rib seals the bottom surface, thereby isolating the breathable membrane ( 118 ,  218  or  418 ). In other words the pressure use case isolates the passive pressure equalization vent. 
     The self-pressure equalization provided by the assembly provides for automatic venting and sealing. The venting and sealing assembly is easy to test in that the breathable membrane  118 ,  218 ,  318 ,  418  need not be removed from the radio system prior to vacuum test, eliminating post-test alignment issues. A vacuum test can be performed during assembly of the product as opposed to just the membrane, thus advantageously allowing for the detection of even small leaks. No disabling of the breathable membrane, such as with water, is needed, during testing, thereby facilitating testing in a dry environment. Accordingly, there has been provided a waterproof venting and sealing system incorporated into a single portable communication device having a limited spatial form factor. 
     Any communication device where ruggedness and good sealing in a small form factor are desired can benefit from the venting and sealing assembly apparatus of the various embodiments. 
     In the foregoing specification, specific embodiments of the present invention have been described. However, one of ordinary skill in the art appreciates that various modifications and changes can be made without departing from the scope of the present invention as set forth in the claims below. Accordingly, the specification and figures are to be regarded in an illustrative rather than a restrictive sense, and all such modifications are intended to be included within the scope of present invention. The benefits, advantages, solutions to problems, and any element(s) that may cause any benefit, advantage, or solution to occur or become more pronounced are not to be construed as a critical, required, or essential features or elements of any or all the claims. The invention is defined solely by the appended claims including any amendments made during the pendency of this application and all equivalents of those claims as issued.