Abstract: In a speaker which is constructed in a manner that a voice coil bobbin is attached to an inner circumferential portion of a cone type diaphragm while a voice coil is wound around the voice coil bobbin, and the voice coil is inserted into a magnetic gap, the voice coil bobbin is formed of a conductive material and is provided with a gap extending a lengthwise direction so as to form a one-turn voice coil, and the voice coil is fixed to the voice coil bobbin by a soft bonding agent while a very high frequency audio signal is supplied to the one-turn voice coil forming the voice coil bobbin.

Abstract: In a speaker which is constructed in a manner that a voice coil bobbin is attached to an inner circumferential portion of a cone type diaphragm while a voice coil is wound around the voice coil bobbin, and the voice coil is inserted into a magnetic gap, the voice coil bobbin is formed of a conductive material while the voice coil being fixed is the voice coil bobbin by a soft bonding agent, and in a very high range, the voice coil is operated as a driving coil while the voice coil bobbin is operated as a short coil.

Abstract: An electro-acoustic transducer, such as a speaker device or an earphone device. Includes an electro-acoustic transducing unit, such as a speaker unit, for converting input electrical signals into sound, a casing in which the electro-acoustic transducing unit is arranged and which delimits a back cavity towards the rear side of the electro-acoustic transducing unit, and at least two openings having a sound duct communicating with the back cavity. The sound radiated from the back surface of the electro-acoustic transducing unit is attenuated by being transmitted into the inside of the sound duct to prevent the radiated sound from being re-admitted into the electro-acoustic transducer.

Abstract: An electromagnetic induction type acoustic transducer apparatus including a magnetic gap formed between a plate and a pole piece serving as assemblies of a magnetic circuit, a conductive ring attached to a diaphragm, the diaphragm interposed within the magnetic gap for generating sounds when it is vibrated, and a flat coil disposed in the plate or the pole piece at the position opposing the magnetic gap and of which winding is increased from the vibration direction of the diaphragm to the direction perpendicular to the vibration direction of the diaphragm, wherein a width of the magnetic gap can be reduced.

Abstract: A speaker apparatus capable of reproducing from low-pitched to high-pitched sounds and a voice reproduction system employing the same. The speaker apparatus includes a speaker unit in which a primary coil is mounted in a gap portion between a plate and a center pole of a magnetic circuit, a secondary coil is disposed within the gap in such a manner as to be fixed to a vibration plate, and a secondary electric current is induced in the secondary coil by a signal current flowing through a primary coil, thereby operating the vibration plate; and a speaker driving circuit adapted to drive the primary coil of the speaker unit in accordance with a digital sound signal.

Abstract: An electromagnetic induction type acoustic transducer including a plate as an assembly of a magnetic circuit and having an opening of a predetermined diameter about a central axis, a pole piece as an assembly of the magnetic circuit and protruded on the central axis, having an outer peripheral diameter smaller than the opening of the plate and having an upper surface located lower than a lower surface of an opening peripheral portion of the plate by a predetermined distance, a lower surface portion of the opening peripheral portion of the plate and an upper surface portion of the pole piece constitute a magnetic gap of the magnetic circuit,a diaphragm vibrated in the upper and lower direction on the central axis at the position perpendicular to the central axis in the predetermined distance, an annular ring attached to the diaphragm at the position of the magnetic gap, and a coil attached to the plate and/or pole piece.

Abstract: A speaker apparatus which drives an electromagnetic-coupling-type speaker in accordance with a digital signal is provided with a speaker unit, and a plurality of amplifiers corresponding to the number of quantization bits of a digital audio signal. The output terminals of the amplifiers are connected to the respective primary coils, respectively, and the output impedances of the plurality of the amplifiers are made equal to those of the respective primary coils to which the amplifiers are connected. Each bit of each sample of the digital audio signal is amplified by the plurality of the amplifiers and supplied to the respective primary coils, respectively.

Abstract: A speaker device driving drive coils of a speaker such as an electromagnetically coupled speaker by digital sound signals, where a primary coil of the speaker unit is constituted by 15 pieces of coils, the coils are made to correspond to respective bits excluding MSB of a digital sound of 16 bits issued from a serial/parallel converter, each of the coils are connected in a bridge connection to 4 pieces of FETs respectively opposed to each other and constant current sources are connected to the bridge connection portions whereby a coil drive circuit is constituted, currents from the constant current sources are respectively supplied to the coils and a variable resistor is adjusted by which voltages are changed and the currents of the constant current sources are commonly controlled whereby the volume of the speaker is finely driven.

Abstract: A speaker apparatus includes a yoke formed of a magnetic material and having a flange portion and a center pole protruded integrally forwards from a mid portion of the flange portion, and a ring-shaped driving magnet into which the center pole is inserted. The speaker apparatus also includes a top plate mounted on the driving magnet. The top plate is formed of a magnetic material and the center pole is inserted through the top plate. The top plate defines a magnetic gap together with the center pole. The speaker apparatus further includes a voice coil mounted on a bobbin secured to a diaphragm in the magnetic gap, and a canceling magnet arranged on the outer periphery of and spaced from the driving magnet at a pre-set spacing for covering the driving magnet. The canceling magnet cancels the magnetic flux leaking to outside a magnetic circuit including the driving magnet.

Abstract: The present invention relates to a so-called bass-reflex electroacoustic transducing apparatus, wherein a plurality of sound ducts (ports) having the same equivalent mass and different lengths are provided in communication with a housing which incorporates therein an electroacoustic transducing element. Thus, resonance and antiresonance generated in respective sound ducts cancel each other out, thereby preventing a tone quality of a reproduced sound from being deteriorated.