A hearing instrument for insertion into the user'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.
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.
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.
A conforming plug 30 for the opening 20 is illustrated in
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.
The conforming plug 30 is shown in a cross-sectional view in
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.
The plug 30 may also have two or more optional latches 42 for securing the plug 30 in the opening 20, as illustrated in
Before tumbling, the conforming plug 30 is pushed into the opening 20 of the shell 10, initially breaking the thin supporting members 34 (see
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