Transducer motor structure with enhanced flux

摘要

An electro-dynamic loudspeaker transducer's motor structure includes a magnetic circuit having a pole with minimal reluctance that allows the use of larger magnets and thicker front plates, thus generating higher flux density in the voice coil gap. The lower reluctance is achieved by increasing the pole piece's outside diameter at all points outside of the voice coil gap and the area swept out by the voice coil at maximal inward excursion. Increasing the pole's diameter over a substantial amount of the pole's distally projecting length (but not extending into the magnetic gap), provides an increased cross sectional area and a reduced magnetic circuit reluctance.

主权项

1. An electro-dynamic loudspeaker transducer motor structure, comprising:
(a) an annular magnet having a central lumen defined around an axis and having an axial length, said magnet being oriented with a first magnetic pole at a first magnet surface and a second opposing pole at a second magnet surface; (b) an annular front plate proximate the magnet's first surface and having a front plate central lumen coaxially aligned with said magnet's central lumen and defining an inner edge with a thickness defined as front plate inner edge axial length, wherein said front plate lumen has a selected lumen inside diameter; (c) a rear pole piece proximate the magnet's second surface and having distally or frontwardly projecting axially aligned elongated pole piece segment configured to be received in the magnet's central lumen, said elongated pole piece having a sidewall with an outer circumferential edge; (d) wherein an annular magnetic gap is defined between the inner edge of the front plate and the outer circumferential edge of the sidewall of the distally projecting pole piece; (e) wherein the distally projecting axially aligned pole piece's sidewall has an enlarged, proximal segment having an enlarged outside diameter and a distal segment having a second outside diameter which is smaller than said enlarged outside diameter; and (f) wherein said distally pole piece sidewall proximal segment's enlarged outside diameter is larger than said front plate's selected lumen inside diameter.