Abstract: The invention relates to an acoustic transducer for broad-band loudspeakers or magnet-free, electrodynamic head-phones for generating sound, especially for the use in the homogenous and/or inhomogeneous magnetic field of a magnetic resonance tomograph. According to the advantages of the invention, sound having defined characteristics can be generated in such a way that said sound is provided with good quality and high effectiveness within the strong magnetic field of a magnetic resonance tomograph. In addition to music and voice, this comprises the generation of sound for actively controlling noise by generating sound by means of one or several membranes (1) that form air pockets. Said membranes (1) consist of elastic, non-magnetic or slightly magnetic material and are connected to strip conductors (2) in a two-dimensional and solid manner. A Lorentz force which is caused by the magnetic field of the magnetic resonance tomograph is exerted on said strip conductors as the driving power when current flows.

Abstract: A piezoelectric speaker improved in acoustic features by weight reduction of a diaphragm of the piezoelectric speaker without decreasing stiffness of the diaphragm or a coefficient of thermal expansion of surfaces of the piezoelectric speaker is provided. The diaphragm having placed thereon a piezoelectric element is made of a sandwich-laminate clad material using different materials. For example, surface materials 7 made of 42 alloy each having a thickness of 10 &mgr;m and a core material 8 made of aluminium having a thickness of 30 &mgr;m form a clad material having a thickness of 50 &mgr;m. The formed clad material is processed into an arbitrary shape to form the diaphragm of the piezoelectric speaker. With this diaphragm, it is possible to keep the stiffness and the coefficient of thermal expansion of the 42-alloy diaphragm having the thickness of 50 &mgr;m, and also achieve weight reduction by approximately 40%.

Abstract: A flat panel sound radiator having improved audio performance is provided. The sound radiator has a panel to which is coupled a traditional electromechanical exciter for imparting audio frequency vibrational energy to the panel. The panel has a honeycomb core made of Kraft paper, which is flexible, has a low self noise, and high noise damping characteristics. The core is sandwiched between facing skins made of a material with a high Young's modulus, a high tan delta, a high tensile strength, and low self noise. Preferably, this material is an aramid polyamide such as Kevlar®, Nomex®, Conex®, or Technora®, all of which exhibit these properties. The facing skins are fixed to the core with an adhesive that is flexible and has high acoustic damping qualities and high shock resistance, such as rubber cements, silicone adhesives, and water-based acrylic adhesives.

Abstract: A loudspeaker in which the input resistance is improved and the effect of humidity on the playback frequency response is suppressed, and a method for the preparation of the loudspeaker. A sheet-like product, containing glass particles with a particle size of 8 nm to 300 nm and polyamide resin, and prepared by application of a paper-making technique, is used as the diaphragm. The content of the glass particles in the compound material is 5 weight % to 70 weight %. In preparing the diaphragm, a phase of an aqueous solution containing diamine and water glass is contacted with a phase of an organic solution containing a dicarboxylic acid halide to generate a compound material containing glass particles and the polyamide resin. The compound material so prepared is formed into a sheet by a paper-making technique. In the process of the preparation by the paper-making technique, the compound material mixed with other fibrous material may also be used as a starting material.

Abstract: Active acoustic device comprises a panel member (11) having distribution of resonant modes of bending wave action determining acoustic performance in conjunction with a transducer (31-34). The transducer (31-34) is coupled to the panel member (11) at a marginal position. The arrangement is such as to result in acoustically acceptable action dependent on said distribution of active said resonant modes. Methods of selecting the transducer location, or improvement by location of localized marginal clamping, rely on assessing best or better operative interaction of said transducer (31-34) and the panel members (11) according to parameters of acoustic output for the device as an acoustic radiator.

Abstract: A laminated aluminum polypropylene (refers to LAP hereinafter) multi-layers loudspeaker diaphragm comprises different material layers to exploit the appearance feature and mechanical properties from different material. LAP diaphragm contains (1) the front layer which is made of formed aluminum foil, (2) the second layer which is injected polypropylene and (3) a bonding adhesive layer lying between the aluminum and polypropylene layers to bond two different material layers tightly and also enhance the property of internal loss. The loudspeaker with this multi layers vibrating diaphragm posses the advantages of the metal glaring appearance and mechanical properties good for quality sound reproduction and environmental resistance.

Abstract: An audio speaker including a chassis and a diaphragm defining an axis. A suspension movably interconnects the diaphragm and the chassis for reciprocating movement of the diaphragm along the axis. A motor is operably connected to the diaphragm for powered movement thereof. The diaphragm includes front and rear skins, and at least a portion of the skins have a generally conical shape. The skins define outer peripheral edges, and are interconnected at the outer peripheral edges with the conical shapes oriented in opposing directions to form a cavity between the skins having an enlarged central portion tapering to a thinner peripheral portion adjacent the outer peripheral edges. The cavity is at least partially filled with a lightweight core material to support the front and rear skins.

Abstract: This invention provides a method of manufacturing speaker diaphragm for a loudspeaker that has a composite material formed of two layers of ceramic material separated by a light metal substrate and where the core is formed by stamping a sheet of standard gauge aluminum to form a speaker core and then deep anodizing the core to obtain a ceramic layer of alumina on each surface (Al2O3) that is at least about 1 mil. thick. The invention further provides for a loudspeaker diaphragm, where the diaphragm is a composite material formed of at least two layers of ceramic material having a metal substrate therebetween and where the thickness of the metal substrate is no more than 86% of the thickness of the composite material.

Abstract: An acoustic diaphragm arranged to face a driving device of a loudspeaker is disclosed. The acoustic diaphragm comprises at least one laminated structure, one of which includes a first carbon fiber layer, a glue layer formed on the first carbon fiber layer, and a second carbon fiber layer formed on the glue layer. The acoustic diaphragm of the present invention has small distortion of sound, less deformation by external force, better stereo, and sound quality, as compared with a conventional diaphragm.

Abstract: A speaker device includes a speaker diaphragm composed of a selected acoustic diaphragm material whose acoustic loss coefficient (tan &dgr;) is more than 0.02 in a frequency band over 20 kHz, and including a dome positioned at the center and shaped to be substantially arcuate in its cross section, and an edge positioned outside the dome and formed integrally therewith through a link; and a conductive one-turn ring inserted into a magnetic gap and bonded fixedly, at one end thereof, to the link between the dome and the edge of the speaker diaphragm. In this device, signals of a frequency band over 20 kHz are reproduced by utilizing the split vibrations of the speaker diaphragm.

Abstract: Disclosed is a piezoelectric diaphragm with a transparent piezoelectric member and a transparent electrode. Also disclosed is a portable electronic device that has a display means to display an image and a piezoelectric speaker having a transparent piezoelectric member and a transparent electrode. In this portable electronic device, the piezoelectric speaker is disposed in front of the display means.

Abstract: Various embodiments of low-mass sound generators each having a wide frequency band are disclosed. In some embodiments, the acoustic transducer acting as the sound generator is constructed of four layers of PVDF film. The top and bottom bi-laminate members are separately formed in a pre-curved manner to form a rippled geometry.

Abstract: A flat panel rectangular or elliptical loudspeaker has one or more anisotropic diaphragms 14, 15, made of double skinned fluted polypropylene copolymer (core flute) or corrugated cardboards having a longitudinal bending strength greater than the transverse bending strength. The diaphragm is vibrated by a driver unit 16 which comprises a magnet 17 and voice coil 18. In this version the magnet 17 is mounted on the rear diaphragm 15 and the voice coil 18 is mounted on the front diaphragm 14. The two diaphragms 14, 15 are mounted at their edges to a frame 11 with the driver unit 16 mounted in the space enclosed by the frame and the diaphragms.

Abstract: A method of manufacturing speaker diaphragm for a loudspeaker that has a composite material formed of two layers of ceramic material separated by a light metal substrate and wherein the core is formed by stamping a sheet of standard gauge aluminum to form a speaker core and then deep anodizing the core to obtain a ceramic layer of alumina on each surface (Al2O3) which is at least about 1 mil. thick.

Abstract: An electroacoustic transducer which includes at least one stator member with an operating surface positioned adjacent to an emitter diaphragm. The stator member is comprised of at least one stiff sheet of paper having perforations for acoustic transparency. The stator also includes a means to develop electrical conductivity and to receive an applied voltage. An emitter diaphragm is suspended adjacent to and spaced a sufficient distance from the operating surface of the stator member to enable diaphragm oscillation in response to an applied signal voltage. This arrangement permits diaphragm movement within at least one emitter section without creating restrictive contact on the operating surface of the stator member. The diaphragm may be composed of paper with electrical conductivity sufficient to receive an acoustic signal voltage from a voltage source and to vibrate as an acoustic emitter with respect to forces applied at the stator member.

Abstract: The speaker member of the present invention comprises (a) a vibrating plate part comprising a base material, a part of the base material being impregnated with a thermosetting resin; and (b) an edge part containing the same base material as that of the vibrating plate. Such a speaker member is obtained by a method comprising the steps of: forming a base material; impregnating a portion of the base material with a thermosetting resin wherein the portion is to be a vibrating plate part; and curing said impregnated thermosetting resin so as to form the vibrating plate part, and simultaneously forming an edge part.

Abstract: A trim panel, e.g., a roof lining for a vehicle passenger compartment, characterized in that the trim panel comprises an integral acoustic radiator and a vibration exciter mounted on the radiator to launch bending waves into the radiator to cause it to resonate to produce an acoustic output. The acoustic radiator has a periphery which is integral with the radiator and the trim panel.

Abstract: A diaphragm for a speaker comprises a metal cone 2 and a paper auxiliary cone 4 bonded integrally to the center portion of the metal cone 2.

Abstract: A speaker diaphragm for a loudspeaker that has a composite material formed of two layers of ceramic material separated by a light metal substrate with the percentage ratio of the thickness of the ceramic layers to the light metal substrate being in the range of from about 10% to 45% for each ceramic layer and a corresponding 80% to 10% for the lightweight metal substrate.

Abstract: A damped structural panel includes a panel having bending modes including demanding bending modes. The demanding bending modes have subsonic bending waves along at least one axis, and require damping treatment based on sound radiation properties of the panel. A viscoelastic material is applied within a limited area adjacent to the panel edges based on the demanding bending modes. The viscoelastic material damps sound radiation caused by bending waves during use of the structural panel, such as use as a body panel on an aircraft.

Abstract: Planar magnetic acoustic transducer diaphragms are formed from an electrical non-conducting membrane and metallic layer laminate by selectively removing portions of the metallic layer to create at least one electrical conductor circuit pattern and at least one passive metallic area both of which are of a predetermined size and configuration to balance modal behavior of the diaphragms when in use.

Abstract: A ceiling tile adapted to be supported in an overhead opening and function as a loudspeaker. The tile is in the form of a distributed mode acoustic radiator with a transducer mounted wholly and exclusively on the radiator at a location for coupling to resonant bending wave modes so as to vibrate the radiator and cause it to resonate.

Abstract: An electroacoustic transducer, which has a diaphragm, a support member for supporting the diaphragm, a pole piece placed inside the support member and comprising a core and a base, a coil wound around the core, and a magnet placed between the support member and the coil, in which the diaphragm is made of resin to which a magnetization is applied.

Abstract: A composite loudspeaker diaphragm is disclosed having first and second substantially flat carbon fiber skins, and a honeycomb core sandwiched between the first and second carbon skins. In a preferred form, each carbon fiber skin comprises a sheet formed of primarily unidirectional carbon filaments bound together by an epoxy resin. In the preferred embodiment, the honeycomb core is formed of nomex, and is glued with epoxy to the first and second carbon skins, and then heated. The sandwich diaphragm is manufactured so that the direction of the carbon fibers of the cross plies of each outer skin are out of phase relative to each other, preferably in the range of approximately ninety degrees. The improved diaphragm is used in an flat-panel loudspeaker system having improved performance at higher frequencies.

Abstract: A head-phone having a case member storing therein a headphone unit, wherein a coating film containing a light discolor pigment to be discolored by irradiation of sun light is provided on the whole surface or a predetermined surface of the case member.

Abstract: An arrangement for minimizing acoustic reflections and diffraction from an exterior surface of a diaphragm of a loudspeaker transducer. A layer of highly optimized acoustic foam is applied to an exterior surface of the transducer diaphragm. The acoustic foam is a polyether urethane material of approximately 2 lb/ft.sup.3 density with a skinned bottom surface, optional skinned top surface and optimized cell size and structure. The foam is die cut into a shape to conform to the concave shape of the transducer diaphragm without large air gaps or deformation of the foam. The acoustic foam surface prevents reflection and diffraction of another transducer's output off of the diaphragm of the treated transducer and provides a low pass filtering of the acoustic output of the treated transducer.

Abstract: Water-proofed natural pulp or organic synthetic fibers are with polyester-type fibers having a low melting point, and subjected to a paper fabrication process. The fabricated product is dried with hot air at a temperature higher than the melting point of the polyester-type fibers, thereby melt-bonding only intersections of the fibers without completely fusing the polyester-type fibers. The pressure of the hot air contributes to the formation of a predetermined shape. Thus, a water-proof diaphragm for a loudspeaker, having a large thickness, a low density, a high internal loss and a high stiffness, is obtained. By incorporating the thus formed diaphragm, a high-performance loudspeaker having a low distortion and a broad reproducing range is obtained.

Abstract: A damper for a loud speaker is produced by molding a substrate into a desired shape in which a fabric or knitted cloth composed of core-sheath type conjugate fibers composed of filaments having a core-sheath type structure is used as the substrate. A resin used for forming a core material in the core-sheath type structure functions as a matrix of the substrate. A sheath material having a lower melting point than that of the core material functions as an excipient, and is fused by a heat treatment and then solidified during the molding process, so as to bond together the intersections of fibers constituting the substrate and to cover the surface of the fibers. Thus, only a simple substrate production process is required and a damper for a loud speaker having excellent moldability, water-proofness, and durability is obtained.