Abstract: An electroacoustic transducer has a diaphragm body including a planar diaphragm having an outer periphery in an elongated generally elliptical shape with semicircular ends and major and minor axes, and an elastometic edge having an outer periphery of an elongated generally elliptical shape with semicircular ends and major and minor axes aligned with the major and minor axis of the diaphragm, the edge being wider along the major axis than along the minor axis and coupled at an inner periphery to the outer periphery of the diaphragm. The edge has a concave cross-section perpendicular to the diaphragm. A cylindrical voice coil bobbin is secured at one end to a central area of the diaphragm, and a voice coil is wound on the voice coil bobbin. A molded resin frame having a generally rectangular shape includes an opening conforming in shape to and receiving the diaphragm body, and is connected to and supports an outer periphery of the edge.

Abstract: A loudspeaker unit includes a magnetic system of dual magnetic gaps formed with a permanent magnet disk carrying on both sides top and bottom plates and a cylindrical yoke surrounding the plates to form therebetween upper and lower magnetic gaps, and a vibratory system formed with a cylindrical voice coil bobbin carrying upper and lower voice coils for use in the dual magnetic gaps as disposed in half off-set state with respect to the gaps and a diaphragm coupled to upper end of the bobbin, the bobbin being supported by upper and lower dampers with respect to the magnetic system for vibration in axial directions of the magnetic system, allowing the bobbin to be supported at fulcrums positioned above and below voice-coil driving points.

Abstract: An edge for loudspeaker diaphragm is made by disposing a diaphragm one of a pair of mating molds, disposing a strip-shaped base material of the edge on the said one of the molds, and hot-molding them with the other mold mated with the one mold. Foaming action of the base material occurs, and an eventual foamed edge is integralized with the diaphragm.

Abstract: A damper for a loudspeaker has an improved linearity of the amount of strain caused by the vibrational energy to vibrational energy exerted on the damper to enable the loudspeaker to reproduce sounds in a high fidelity. The damper is formed such that the modulus of elasticity with respect to a direction perpendicular to the surface of the damper is uniform on a circle with its center at the center of the damper, and portions respectively on concentric circles with their centers at the center of the damper are different in modulus of elasticity with respect to a direction perpendicular to the surface of the damper from each other.

Abstract: A loudspeaker has two magnets disposed directly with respect to voice coils for generating a repulsion magnetic field at the voice coils, without interposition of yoke but with mutually repulsing magnetic polarities of the magnets, and a diaphragm directly coupled at inner peripheral edge substantially to the center of outer periphery of the voice coils. Driving force is transmitted highly efficiently from the voice coils to the diaphragm, and the loudspeaker can be sufficiently minimized in the thickness and weight.

Abstract: A receiver including a vibrator plate vibrating together with a voice coil in response to electrification of said voice coil which comprises an electrostatic discharge prevention plate having a central opening arranged above the vibrator plate with a small air gap provided therebetween. A metal cover around the top and sides of the receiver is imbedded in plastic for inhibiting electrostatic discharge via the cover. As a result the discharge path length through the air is substantially increased, reducing the likelihood of electrostatic discharge from the ear of the user.

Abstract: A loudspeaker has two magnets disposed directly with respect to voice coils for generating a repulsion magnetic field at the voice coils, without interposition of yoke but with mutually repulsing magnetic polarities of the magnets, and a diaphragm directly coupled at inner peripheral edge substantially to the center of outer periphery of the voice coils. Driving force is transmitted highly efficiently from the voice coils to the diaphragm, and the loudspeaker can be sufficiently minimized in the thickness and weight.

Abstract: An intra-concha type electroacoustic trasducer has an auxiliary supporter projecting in opposite direction to entrance part of external auditory meatus of the user's ear from a side of the transducer opposite to its sound-radiating side disposed to face the auditory meatus entrance. Reliable mountability of the transducer with respect to auricle of the user's ear is thereby ensured, while an unpleasantness or pain given to the user upon mounting to the auricle can be at least reduced to a remarkable extent.

Abstract: A whole-surface driven speaker includes first and second support plates having sound-passing perforations and groups of magnets mounted on the plates. The plates are substantially parallel to each other. A diaphragm is disposed in between the plates. A plurality of conductor strips are mounted on the surface of the diaphragm. The strips are connected to receive pulse-code modulated signals. The strips respectively correspond to a plurality of binary bits of the signals of different bit significance. Each strip has a predetermined width and a predetermined number of windings and carries a predetermined current magnitude such that electromechanical forces on the diaphragm caused by the bit signals flowing through the strips are proportional to the respective bit significance of the strips.

Abstract: An electrodynamic type electroacoustic transducer wherein a diaphragm of a nonmagnetic and insulative material having thereon a series of conductors is disposed between a pair of magnetic circuits opposing one another through a slight clearance so that the conductors will lie in magnetic flux flowing between opposite polarity ends of at least a pair of permanent magnets in each magnetic circuit and will move in directions transverse the flux when the diaphragm is vibrated, in which the diaphragm is resiliently held in said clearance by means of an elastic support means inserted at least between the diaphragm and the respective opposing pole ends of the magnets in both circuits so as to be prevented from contacting the pole ends when vibrated.