Planar magnetic acoustical transducer stamped pole structures

A planar magnetic acoustic transducer comprising;

• a housing defined by opposing metallic frame sections each having a material thickness of between 0.03 to 0.06 inch, said opposing frame sections defining an open area surrounded by a border portion;
• a flexible diaphragm mounted between said border portions of said frame sections so as to create an active diaphragm area within said open areas defined by said frame sections;
• an electrical circuit on said active surface area of said diaphragm, said electrical circuit including a plurality of generally parallel conductor segments;
• A plurality of permanent magnets mounted in a plurality of spaced rows to each of said frame sections such that said rows of magnets of said frame sections are in opposing relationship with respect to one another on opposite sides and spaced from said diaphragm with like poles of said magnets being in opposing relationship with one another on opposite sides of said diaphragm;
• A plurality of pole elements integrally formed with each of said frame sections and extending inwardly toward said diaphragm, said pole elements being spaced intermediate and from each of said rows of said permanent magnets, each of said pole elements being defined by at least one side wall which extends inwardly toward said diaphragm from a rear wall of said frame sections, said at least one side wall being angled at no greater than 40° with respect to a line extending perpendicularly from said rear wall to said diaphragm;
• and
• a plurality of elongated openings provided through said rear wall of each of said frame sections between each of said rows of magnets and each of said pole elements to allow acoustic waves to pass therethrough whereby magnetic fields from said rows of magnets are directed generally parallel to said diaphragm from said like poles of said permanent magnets to said pole elements.