Electrical audio signal processing systems and devices – Electro-acoustic audio transducer – Electromagnetic
Patent
1998-07-08
2000-02-29
Kuntz, Curtis A.
Electrical audio signal processing systems and devices
Electro-acoustic audio transducer
Electromagnetic
381398, 381429, H04R 2500
Patent
active
060319267
DESCRIPTION:
BRIEF SUMMARY
TECHNICAL FIELD
The invention relates to loudspeakers and more particularly to loudspeakers comprising panel-form acoustic radiating elements.
BACKGROUND ART
It is known from GB-A-2262861 to suggest a panel-form loudspeaker comprising: formed of two skins of material with a spacing core of transverse cellular construction, wherein the panel is such as to have ratio of bending stiffness (B), in all orientations, to the cube power of panel mass per unit surface area (.mu.) of at least 10; body, in a free undamped manner; excite a multi-modal resonance in the radiator panel in response to an electrical input within a working frequency band for the loudspeaker.
U.S. Pat. No. 3,247,925 of WARNAKA discloses what purports to be a low frequency resonant panel loudspeaker mounted in a chassis and excited by an electromechanical transducer mounted on the chassis.
DISCLOSURE OF INVENTION
Embodiments of the present invention use members of nature, structure and configuration achievable generally and/or specifically by implementing teachings of our co-pending application Ser. No. 08/707,012. Such members thus have capability to sustain and propagate input vibrational energy by bending waves in operative area(s) extending transversely of thickness often but not necessarily to edges of the member(s); are configured with or without anisotropy of bending stiffness to have resonant mode vibration components distributed over said area(s) beneficially for acoustic coupling with ambient air; and have predetermined preferential locations or sites within said area for transducer means, particularly operationally active or moving part(s) thereof effective in relation to acoustic vibrational activity in said area(s) and signals, usually electrical, corresponding to acoustic content of such vibrational activity. Uses are envisaged in co-pending application Ser. No. 08/707,012 for such members as or in "passive" acoustic devices without transducer means, such as for reverberation or for acoustic filtering or for acoustically "voicing" a space or room; and as or in "active" acoustic devices with transducer means, such as in a remarkably wide range of sources of sound or loudspeakers when supplied with input signals to be converted to said sound, or in such as microphones when exposed to sound to be converted into other signals.
This invention is particularly concerned with active acoustic devices in the form of loudspeakers. Members as above are herein called distributed mode acoustic radiators and are intended to be characterised as in the above co-pending parent application and/or otherwise as specifically provided herein.
The invention is a panel-form loudspeaker having a member comprising a stiff lightweight panel having capability to sustain and propagate input vibrational energy by bending waves in at least one operative area extending transversely of thickness to have resonant mode vibration components distributed over said at least one area and have predetermined preferential locations or sites within said area for transducer means and having first and second transducers mounted on said member at two of said locations or sites to vibrate the member to cause it to resonate forming an acoustic radiator which provides an acoustic output when resonating. The first and second, transducers may be adapted to operate in different frequency ranges. The radiator may have a cellular core sandwiched between skins. The loudspeaker may comprise a frame supporting the radiator, and a resilient suspension by which the radiator is attached to the frame. The frame may surround the radiator, and the suspension may be attached to the edge of the radiator. The first and second transducers may be mounted wholly and exclusively on the radiator. One of the transducers may be electromagnetic. One of the transducers may be piezo-electric. The panel-form loudspeaker may comprise a second member having capability to sustain and propagate input vibrational energy by bending waves in at least one operative area extending transversely of thickness t
REFERENCES:
patent: 4751419 (1988-06-01), Takahata
patent: 5025474 (1991-06-01), Tanaka et al.
patent: 5748758 (1998-05-01), Menasco, Jr. et al.
patent: 5838805 (1995-11-01), Warnaka et al.
Azima Henry
Colloms Martin
Harris Neil John
Harvey Dionne N.
Kuntz Curtis A.
New Transducers Limited
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