Magnetic electro-acoustic transducer construction
AssigneePlessey Overseas Limited
InventorFrederick Steiner
Life of this patent
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Abstract
A method of making an acoustic transducer for telephones consists of securing the magnet assembly and the armature supporting ring inside the plastic casing of the transducer and then surrounding or partly surrounding these with a thermosetting resin such as epoxy resin, poured inside the casing. The core, the armature supporting ring and the outer edge of the casing are then machined with reference to the magnet face to the required very small tolerances, the cured resin holding the parts securely during the machining operations.
Claims22
An electro-acoustic transducer comprising a walled housing, a stemmed pole piece mounted on the base of the housing having a stem projecting perpendicularly from a plate, a coil wound on the stem, at least one magnet mounted on the plate of the stemmed pole piece arranged to at least substantially surround the coil, a non-magnetic armature supporting member situated on the base of the housing spaced from and surrounding the at least one magnet and a flexible armature supported on the supporting member, the stemmed pole piece, the coil and the at least one magnet being located in spaced relationship on the base of the housing by a thermo-setting resin, the stemmed pole piece, the supporting member and the walls of the housing being machined after curing of the resin whereby the armature is supported on the supporting member with a predetermined space between the armature and the stemmed pole piece.
A method of manufacturing an electro-acoustic transducer comprising the steps of winding a coil on the stem of a stemmed pole piece, the stem projecting from a plate, mounting an at least one magnet on the plate so as to at least surround the coil, locating this assembly within a walled housing within a non-magnetic armature supporting member situated on the base of the walled housing so as to be spaced from and surrounded by the armature supporting member, inserting a quantity of thermo-setting resin into the walled housing and allowing to cure to retain the parts in their respective positions and machining the end of the stem, the top surface of the armature supporting member and the top surfaces of the walls of the housing to predetermined levels in relation to the top surface of the at least one magnet.
Dependencies are inferred from the claim text.