Acoustically enhanced electro-dynamic loudspeakers

Abstract

An electro-dynamic loudspeaker is provided with dampening arrangements that contribute to improved acoustical properties for the electro-dynamic planar loudspeaker. The dampening arrangements include providing a frame having a curved sidewall surface for reducing standing waves. Another design provides for a ferrofluid being disposed between the diaphragm and magnets of the electro-dynamic loudspeaker in order to dampen the resonance frequency of the device. In addition, a diaphragm of an electro-dynamic loudspeaker is provided with a short turn of conductor disposed along a fringe zone at an edge of the diaphragm in order to electro-dynamically dampen the edge resonance of the film.

Description

CROSS REFERENCE TO RELATED APPLICATIONS [0001] This application claims the benefit of U.S. Provisional Application Nos. 60 / 380,001, filed May 2, 2002, 60 / 378,188, filed May 6, 2002, and 60 / 391,134, filed Jun. 24, 2002. These patent applications are incorporated by reference. CROSS REFERENCE TO CO-PENDING APPLICATIONS [0002] This application incorporates by reference the disclosures of each of the following co-pending applications which have been filed concurrently with this application: U.S. patent application Ser. No. ______, entitled “Mounting Bracket System,” filed May 2, 2003; U.S. patent application Ser. No. ______, entitled “Film Tensioning System,” filed May 2, 2003; U.S. patent application Ser. No. ______, entitled “Film Attaching System,” filed May 2, 2003; U.S. patent application Ser. No. ______, entitled “Electrical Connectors For Electro-Dynamic Loudspeakers,” filed May 2, 2003; U.S. patent application Ser. No. ______, entitled “Electro-Dynamic Loudspeaker Mounting Syste...

AI Technical Summary

Benefits of technology

[0017] The invention provides several arrangements and methods for enhancing the acoustical properties of an electro-dynamic loudspeaker. According to one aspect of the invention, the electro-dynamic loudspeaker includes a frame defining a recessed portion having a pair of sidewalls interconnected by a pair of endwalls and at least one of the sidewalls including a plurality of curves along a length of the sidewall. The curves can be in the form of a sinusoidal curve or scallops or another shape that is non-parallel to the opposing sidewall. The curves that are placed in at least one sidewall are provided in order to reduce standing waves that contribute to distortion.

[0018] The electro-dynamic loudspeaker includes a frame including a plurality of magnets mounted to the frame. A diaphragm is mounted to the frame and a ferrofluid is disposed between the diaphragm and the magnets and contacts a lower surface of the diaphragm. A ferrofluid is a stable colloidal suspension of sub-domain magnetic particles in a liquid carrier. The ferrofluid dampens the resonant frequency of the diaphragm in order to reduce distortion and smooth frequency response.

[0019] An electro-dynamic loudspeaker is provided with a shorted turn of conductor disposed along a fringe zone at an edge of the diaphragm. The shorted turn electro-dynamically dampens the edge resonance of the diaphragm.

[0020] A diaphragm of an electro-dynamic loudspeaker is made from a piezoelectric material, such as PVDF (polyvelydeneflouride) and is provided with a current carrying conductor and an undriven conductor applied to both sides of the film material. The undriven conductors are caused to move by the electromotive force on the circuit as the diaphragm vibrates, thus creating electric current through the undriven conductor. The electric current causes the piezoelectric material of the film to expand and contract in response to the electric current, and thereby dampens the film modes to reduce distortion and smooth frequency response. As an alternative, a PVDF strip can also be glued to a PEN (polyethylene naphthalate) film.

Problems solved by technology

Many design and manufacturing challenges present themselves in the manufacturing of electro-dynamic loudspeakers.

Accordingly, designing conductors for electro-dynamic loudspeaker applications presents various challenges such as selecting the speaker with the desired audible output for a given location that will fit within the size and location constraints of the desired applications environment.

Often, space limitations in the listening environment prohibit the use of a loudspeaker in an audio system that possesses the preferred directivity pattern for the system's design.

For example, the amount of space and the particular locations available in a listening environment for locating and / or mounting the loudspeakers of the audio system may prohibit the use of a particular loudspeaker that exhibits the intended directivity pattern.

Also, due to space and location constraints, it may not be possible to position or oriented the desired loudspeaker in a manner consistent with the loudspeaker's directivity pattern.

Consequently, size and space constraints of a particular environment may make it difficult to achieve the desired performance from the audio system.

Unfortunately, the large rectangular size results in a high-frequency beam width angle or coverage that may be too narrow for its intended application.

The frame presents design challenges since it is preferably rigid enough to keep the diaphragm film tension uniform and capable of not deforming during handling, assembly, or over time.

The final assembly may be mounted on a vehicle, and therefore, must be rigid during shipping and handling and should not allow the diaphragm or frame to deform during installation.

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