Abstract:
During tumbling, a plug may be inserted into the opening of a hearing instrument shell to protect the hole and minimize additional cleaning operations subsequent to tumbling. A suitable conforming plug may be fabricated at the same time the shell is made.

Description:
BACKGROUND AND SUMMARY OF THE INVENTION 
       [0001]    A hearing instrument for insertion into the user&#39;s ear canal may be manufactured by using one of the processes, such as stereo lithography, mentioned in U.S. Patent Application Publication No. 2002/0196954 A1, published Dec. 26, 2002 and titled, “Modeling and fabrication of three-dimensional irregular surfaces for hearing instruments,” incorporated here by reference. When the shell of the instrument has been completed, it may be sent to a tumbling process for finishing. 
         [0002]    If the shell has an integral faceplate, such as the one described in U.S. Pat. No. 7,191,029, issued Feb. 21, 2007, and titled, “Rapid Prototype Fabrication of a Monolithic Hearing Instrument Housing with an Integrally-fabricated Faceplate,” incorporated here by reference, it may have an opening that accepts an electronic module. In such a case, it may be desirable to protect the features of the opening that accepts the electronic module from abrasion and wear that may occur during tumbling. 
         [0003]    The opening may be protected by inserting a plug into the opening and then later discarding it. Although the plug could be separately manufactured for the shell, it would be more expedient to fabricate the plug at the same time the shell is made. Further, if stereo lithography or a similar process is employed, it may be advantageous to fabricate the plug as an integral part of the structure that emerges from the manufacturing process. The plug would then pushed down into the module opening where it would engage by virtue of an interference fit or perhaps a latching mechanism. After tumbling, the plug would be removed from the module opening and discarded. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0004]      FIG. 1  is a drawing of a hearing instrument comprising a shell and an opening for an electronics module; 
           [0005]      FIG. 2  is a drawing of the hearing instrument of  FIG. 1  illustrating a plug created with the shell; 
           [0006]      FIGS. 3-5  are partial cross-sectional views of a hearing instrument shell and a plug; and 
           [0007]      FIGS. 6 and 7  are drawings of the hearing instrument of  FIG. 2  where the plug has been inserted into the opening for the electronics module. 
       
    
    
     DESCRIPTION OF THE INVENTION 
       [0008]      FIG. 1  illustrates a hearing instrument shell  10  comprising an opening  20  for an electronics module (not shown). To insure that the module resides securely in the opening  20 , its dimensions must fall within a predetermined design tolerance. During fabrication and in particular during a finishing process such as tumbling, the opening  20  must be protected or the module may not reside properly therein. 
         [0009]    A conforming plug  30  for the opening  20  is illustrated in  FIG. 2 . A fabrication process such as stereo lithography permits fabrication of a conforming plug  30  simultaneously with the shell  10 . As can be seen from  FIG. 2 , the outer contour  32  of the plug  30  conforms to the contour  22  of the opening  20 . 
         [0010]    The fabrication process creates the structure layer by layer in the vertical direction. Assuming that the shell  10  is created first, thin supporting members  34  extend upwardly from the outer surface  12  of the shell  10 , to what will be the underside  36  of the plug  30 . An opening  38  may be provided in the conforming plug  30  to facilitate its later removal from the module opening  20 . 
         [0011]    The conforming plug  30  is shown in a cross-sectional view in  FIG. 3 . As shown in this view, the plug  30  also has a flange  40  that will reside in a conforming recess  16  adjacent the opening  20  for the module, near the top  12  of the shell  10 . (For clarity of the presentation, the recess  16  and the flange  40  are not shown in  FIG. 1  or  2 .) 
         [0012]    The supporting members  34  are configured and sized to easily break and detach from the surface  12  of the shell  10  when the plug  30  is inserted into the opening  20 . The thickness and cross-sectional profile of the supporting members  34  are selected to facilitate their removal from the shell  10  when the plug  30  is inserted into the opening  20 , but provide adequate support during fabrication. For example, where the hearing instrument shell  10  has a thickness of 0.6-1.0 mm and the faceplate has a thickness of 4.0-5.0 mm, the supporting members  34  may have a thickness of 0.5-1.5 mm. The members  34  could have a square, rectangular, circular, elliptical, or other suitable cross-section. 
         [0013]    The plug  30  may also have two or more optional latches  42  for securing the plug  30  in the opening  20 , as illustrated in  FIGS. 4 and 5 . In lieu of latches, the plug  30  could be sized to provide an interference fit within the opening  20 . 
         [0014]    Before tumbling, the conforming plug  30  is pushed into the opening  20  of the shell  10 , initially breaking the thin supporting members  34  (see  FIGS. 6 and 7 ). If latches  42  have been provided for the plug  30 , the latches  42  engage the underside  14  of the shell  10 , as shown in  FIG. 6 . After the tumbling is completed, the plug  30  is removed and discarded. 
         [0015]    If desired, registration marks  50  may be added to the plug  30  and the shell  10  to assist in orienting the plug  30  when it is inserted into the opening  20 . They are schematically illustrated as arrows in  FIG. 7 , but may be of any shape and could be fabricated by making small elevations on the outer surface  12  of the shell  10  and on the plug  30 .