Patent ID: 7885425

Claim:
An electrodynamic electroacoustic transducer comprising: a first magnetic pole part formed by at least one three-dimensional body; a second magnetic pole part which is formed by at least one three-dimensional body, forms a magnetic gap between itself and the first magnetic pole part, and is arranged in a space excluding spaces in upper and lower face directions of the first magnetic pole part; a yoke for magnetically coupling one magnetic pole face of the first magnetic pole part with one magnetic pole face of the second magnetic pole part so as to support them; a diaphragm which is arranged in a space in an upper face direction of the first magnetic pole part and in a space in a lower face direction of the second magnetic pole part, has an outer periphery supported by the yoke, and can vibrate in up and down directions; and a voice coil adhered to the diaphragm and arranged in the magnetic gap, wherein an inner periphery shape of the voice coil is larger than an outer periphery shape of the first magnetic pole part, and the outer periphery shape of the voice coil is smaller than an inner periphery shape of the second magnetic pole part, wherein each of the first magnetic pole part and the second magnetic pole part includes a magnet, and the magnet included in the first magnetic pole part and the magnet included in the second magnetic pole part are magnetized into the same polarity in the vibrating directions of the diaphragm, wherein the first magnetic pole part and the second magnetic pole part generate, within the voice coil, magnetic fluxes perpendicular to the vibrating directions of the diaphragm, and wherein the diaphragm includes an edge part that permits vibration of the diaphragm, while at least a part of the edge part opposes a lower face of the second magnetic pole part.