Fireproof electrical isolation speaker

Claim 1

A fireproof electrical isolation speaker comprising a resilient metal diaphragm for imparting sound impulses into the surrounding area, a diaphragm adjustment ring having a forward lip portion, a diaphragm retaining ring threadably attached to said diaphragm adjustment ring for fixedly holding the outer edge portion of said diaphragm against the lip portion of said diaphragm adjustment ring, a circular metal housing for containing elements of said speaker, said diaphragm adjustment ring being threadably attached to said housing, an annularly shaped permanent magnet centrally positioned in said housing, an iron cup disposed around the outer and lower surfaces of said magnet, an annular coil positioned on the upper surface of said magnet within the upper portion of said iron cup, a cylindrical iron core having one end located in the central opening of said annular coil, the other end of said iron core extending forward toward the inner surface of said diaphragm and spaced therefrom, said diaphragm adjustment ring having a vent hole through the wall thereof to prevent ambient pressure changes behind said diaphragm and allow freedom of lateral movement in response to magnetic impulses transmitted by said iron core, and an isolation plug fixedly positioned between said coil and said diaphragm and between the outer wall of said iron cup and said metal housing, said iron core being press fitted into said isolation plug and contacting the surface of said permanent magnet thereby magnetically transmitting the voice impulses received from said coil to said metal diaphragm.