Harness, Dickey & Pierce, P.L.C.
Directional dynamic microphone interchangeable to have unidirectional and superdirectional characteristics
A directional dynamic microphone includes a protective cover, a diaphragm in air-tight engagement with the cover, a voice coil, and a magnet with a core pole member and a tubular pole member and disposed rearwardly of the diaphragm. The magnet has an outer front circumferential portion which is spaced apart from an annular wall of the cover to confine a sound passage therebetween, an outer intermediate circumferential portion which engages the annular wall and which defines a sound port opening outwardly and radially for air communication with the sound passage, and an outer rear circumferential portion with sound holes angularly displaced therein and smaller than the sound port. Each sound hole extends inwardly and radially for air communication with a rear major side of the diaphragm. A phase shift effecting sheet veils the sound port so as to impart the microphone with a unidirectional characteristic. A cylindrical shield member is sleeved on and is retainingly slidable relative to the outer rear circumferential portion, and has through holes. When the through holes are not registered with the sound holes to deny entry of a sound wave into the sound holes, the microphone is unidirectional. When the through holes are registered with the sound holes to admit the sound wave thereinto, the microphone is superdirectional.
H
H04R
inventional
Ching-Lu
Chang