Patent ID: 6205228
Filing Date: 2001-03-20
Classification: H04R

Abstract:
An electrodynamic electro-acoustic transducer having an acoustic axis, said transducer comprising:a pleated ribbon diaphragm having a plurality of half-pleats each extending along a first direction perpendicular to the acoustic axis of the transducer and each adapted to move in an accordion-like manner in a second direction perpendicular to both said first direction and to said acoustic axis of the transducer, said first and second directions defining a diaphragm plane;an electrical conductor comprising one or more conductive strands each extending along a respective one of said half pleats parallel to the diaphragm plane;a horn having at least an outer portion that is perpendicular to the diaphragm plane;a magnetic front pole plate extending across a front side of an active area of the diaphragm and disposed between said active area and the horn for providing an acoustic conduit between said active area and the horna rear pole plate extending across a rear side of the active area and cooperating with the magnetic front pole plate for orienting a magnetic field in a direction perpendicular to said active area,wherein:the front and rear pole plates each comprises a plurality of openings,each of the openings in the front pole plate extends from a rear surface adjacent the active area of the diaphragm transducer to a front surface adjacent an interior portion of the horn,the rear open area of each of the openings in said rear surface is less than the corresponding front open area of that same opening in said front surface, andthe ratio of rear open area to the front open area in the front pole plate is substantially constant for all portions of the active area of the diaphragm.