Patent Publication Number: US-2021193408-A1

Title: Hermetically sealed over-molded button assembly

Description:
INCORPORATION BY REFERENCE TO ANY PRIORITY APPLICATIONS 
     Any and all applications for which a foreign or domestic priority claim is identified in the Application Data Sheet as filed with the present application are hereby incorporated by reference under 37 CFR 1.57. 
     BACKGROUND OF THE INVENTION 
     Field of the Invention 
     The subject invention is directed to a button assembly, and more particularly, to a hermetically sealed over molded button assembly for activating an electronic switch of a communication device. 
     Description of the Related Art 
     It is known in the art to use an adhesive to bond a rubber button to the plastic housing of a communication device for activating an electronic switch within the housing. Overtime, the edges of the rubber button can peel away from the plastic housing, leaving the electronic switch susceptible to the environment. Adhesive bonding is also a time consuming manufacturing technique. Accordingly, there is a need in the art for a more durable, externally sealed interface between a rubber button and a plastic housing that does not require adhesive bonding or any other type of fastener. 
     The subject invention overcomes the above-noted deficiencies of the prior art button assemblies by providing a rubber button that is over-molded on a plastic cover, which is then ultrasonically or laser welded to a plastic housing. This assembly process eliminates the need for adhesives and creates a durable seal from the environment by compressing the rubber button between the plastic cover and housing. The welding process provides a further improvement over the time consuming adhesive bonding process used in the prior art, because the button assembly of the subject invention is sealed immediately after the welding process is performed, rather than having to wait for the adhesive to bond. 
     SUMMARY OF THE INVENTION 
     The subject invention is directed to a new and useful button assembly for actuating an electronic switch, and more particularly, to a hermetically sealed over-molded button assembly for activating an electronic switch associated with a data communication system. The button assembly of the subject invention includes a plastic cover and an elastomeric button that is over-molded on the plastic cover, and then the plastic cover is mechanically attached a plastic housing, so that the rubber button is compressed between the cover and the housing, creating a robust structural seal between the button and the housing. 
     The plastic housing includes a wall having an exterior surface and an interior surface. The wall of the housing has an aperture extending therethrough from the exterior surface to the interior surface, and a raised ridge is formed on the exterior surface of the wall surrounding the aperture. The cover includes an upper body portion and a lower flange portion. The upper body portion has a top wall and an interior cavity. A port is formed in the top wall of the upper body portion of the cover. 
     The button includes an upper actuation portion and a lower body portion. The upper actuation portion of the button extends through the port formed in the top wall of the cover. The lower body portion of the button resides within the interior cavity of the upper body portion of the cover. The lower body portion of the button has an outer wall with a bottom surface having a channel for accommodating the raised ridge surrounding the aperture in the housing. The outer wall of the button includes a downwardly extending sealing lip for engaging an interior surface of the aperture formed in the wall of the housing. The outer wall of the button surrounds an interior actuation chamber and an actuation post extends downwardly from the actuation portion of the button within the interior actuation chamber for contacting a switch located below the interior surface of wall of the housing when the actuation portion of the button is depressed. 
     The subject invention is also directed to a button assembly that includes a plastic cover and an elastomeric button over-molded on the plastic cover. The plastic cover includes an upper body portion having a top wall and an interior cavity. A port is formed in the top wall of the upper body portion and the lower flange portion is adapted and configured to be welded to a wall of a plastic housing. The elastomeric button includes an upper actuation portion and a lower body portion. The upper actuation portion extends through the port formed in the top wall of the upper body portion of the cover, and the lower body portion resides in the interior cavity of the upper body portion of the cover. 
     Preferably, the lower body portion of the button includes an outer wall having a bottom surface with a channel for accommodating a raised ridge surrounding an aperture formed in the wall of the housing and a downwardly extending sealing lip for engaging an interior surface of the aperture. Preferably, the outer wall of the lower body portion of the button surrounds an interior actuation chamber and an actuation post extends downwardly from the actuation portion of the button within the interior actuation chamber for contacting a switch located below an interior surface of the wall of the housing when the actuation portion of the button is depressed. 
     The subject invention is also directed to a method of constructing a button assembly, which includes the steps of providing a plastic cover, providing or otherwise over-molding an elastomeric button on the plastic cover, and mechanically attaching the plastic cover to a plastic housing by ultrasonic or laser welding. 
     These and other features of the hermetically sealed over-molded button assembly of the subject invention will become more readily apparent to those having ordinary skill in the art to which the subject invention appertains from the detailed description of the preferred embodiments taken in conjunction with the following brief description of the drawings. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       So that those having ordinary skill in the art will readily understand how to make and use the hermetically sealed over-molded button assembly of the subject invention without undue experimentation, preferred embodiments thereof will be described in detail herein below with reference to the figures wherein: 
         FIG. 1  is a perspective view of the hermetically sealed over-molded button assembly of the subject invention; 
         FIG. 2  is an exploded perspective view of the button assembly of  FIG. 1 , with parts separate for ease of illustration; 
         FIG. 3  is a cross-sectional view of the button assembly of the subject invention taken along line  3 - 3  of  FIG. 1 ; and 
         FIG. 4  is an enlarged localized cross-sectional view from  FIG. 3 . 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     Referring now to the drawings wherein like reference numerals identify similar structural elements or features of the subject invention, there is illustrated in  FIG. 1  a new and useful button assembly for actuating an electronic switch, and more particularly, to a hermetically sealed over-molded button assembly for activating an electronic switch associated with a communication device such as, for example a thermally enhanced night vision goggle system, as disclosed in commonly assigned U.S. Pat. No. 9,705,605, the disclosure of which is herein incorporated by reference 
     The button assembly  10  of the subject invention includes a thermoplastic cover  12  and an elastomeric or rubber button  14  that is over-molded on the thermoplastic cover  12  (i.e., the substrate). The thermoplastic cover  12  is then mechanically attached to a thermoplastic housing  16  by ultrasonic or laser welding. As a result of this joining process, the rubber button  14  is advantageously compressed between the cover  12  and the housing  16 . This creates a robust structural seal between the rubber button  14  and the plastic housing  16 . Moreover, a durable, externally sealed interface is formed between the rubber button  14  and the plastic housing  16  that protects electronic components in the housing from the environment and does not require adhesive bonding. 
     The plastic housing  16  includes an outer wall  20  having an exterior surface  22  and an interior surface  24 . The wall  20  of the plastic housing  16  has an aperture  26  that extends through the wall  20  from the exterior surface  22  thereof to the interior surface  24  thereof. A raised ridge  28  is formed on the exterior surface  22  of the wall  20  surrounding the periphery of the aperture  26 . 
     The thermoplastic cover  12  of the button assembly  10  includes an upper body portion  30  and a lower flange portion  32 . The upper body portion  30  of the cover  12  has a top wall  34  and an interior cavity  36 . A circular port or aperture  38  is formed in the top wall  32  of the upper body portion  30  of the cover  12 . Integral weldment assistance structure  35  is provided on a contacting surface  37  of the lower flange portion  32 , for interacting with the exterior surface  22  of the plastic housing  16  during fabrication. 
     The rubber button  14  of the button assembly  10  includes an upper actuation portion  40  and a lower body portion  42 . The upper actuation portion  40  of the rubber button  14  extends through the port  38  formed in the top wall  32  of the plastic cover  12 . The lower body portion  42  of the button  14  resides within the interior cavity  36  of the upper body portion  30  of the cover  12 . 
     The lower body portion  42  of the button  14  has an outer wall  44  with a bottom surface  46  having a channel  48  for accommodating and compressing the raised ridge  28  surrounding the aperture  26  in the housing  16 . 
     The outer wall  44  of the button  14  includes a downwardly extending radially inner sealing lip  50  for engaging an interior surface  25  of the aperture  26  formed in the wall  20  of the housing  16 . This interface hermetically seals the aperture  26  from the environment, protecting electronic components located within the housing  16 . 
     The outer wall  44  of the button  14  surrounds an interior actuation chamber  52  and an actuation post  54  extends downwardly from the upper actuation portion  40  of the button  14  within the interior actuation chamber  52  for contacting a switch located on a PCB 
     below the interior surface  24  of wall  20  of the housing  16 , when the upper actuation portion  40  of the button  14  is depressed. 
     In sum, the subject invention describes a method of constructing a button assembly  10 , which includes the steps of providing a thermoplastic cover  12  (the substrate), over-molding an thermoplastic elastomer (TPE) button  14  on the thermoplastic cover  12 , and mechanically attaching the thermoplastic cover  12  to a thermoplastic housing  16  by ultrasonic or laser welding. 
     While the subject disclosure has been shown and described with reference to preferred embodiments, those skilled in the art will readily appreciate that changes and/or modifications may be made thereto without departing from the scope of the subject disclosure. 
     For example, while the over-molded button assembly  10  of the subject invention has been discussed in association with a communication system, those skilled in the art will readily appreciate that the over-molded button assembly  10  can be utilized with any type of electronic device that has a thermoplastic housing. 
     In addition, while the over-molded button assembly  10  and the aperture  26  provided in the housing  16  are shown and described as having a generally rectangular or square configuration, the button assembly and the aperture could be configured in virtually any shape, such as, for example, circular, oblong or oval, as dictated by design.