Acoustic device

Details Acoustic device Acoustic device

1999-09-03

2001-08-28

Tran, Sinh (Department: 2743)

Electrical audio signal processing systems and devices

Electro-acoustic audio transducer

Electromagnetic

C381S431000, C381S424000

Reexamination Certificate

active

06282298

ABSTRACT:

FIELD OF THE INVENTION
This invention relates to acoustic devices capable of acoustic action by bending waves and typically (but not exclusively) for use in or as loudspeakers.
BACKGROUND TO THE INVENTION
Our co-pending earlier patent application Ser. No. 08/707,012 includes general teaching as to nature, structure and configuration of acoustic panel members having capability to sustain and propagate input vibrational energy through bending waves in acoustically operative area(s) extending transversely of thickness usually (if not necessarily) to edges of the member(s). Specific teaching includes analyses of various specific panel configurations with or without directional anisotropy of bending stiffness through/across said area(s) so as to have resonant mode vibration components distributed over said area(s) beneficially for acoustic coupling with ambient air; and as to having determinable preferential location(s) within said area(s) for acoustic transducer means, particularly operationally active or moving part(s) thereof effective in relation to acoustic vibrational activity in said area(s) and related signals, usually electrical, corresponding to acoustic content of such vibrational activity. Uses are also envisaged in that earlier patent application for such members as or in “passive” acoustic devices, i.e. 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 bending wave transducer means, including in a remarkably wide range of loudspeakers as sources of sound when supplied with input signals to be converted to said sound, and also in such as microphones when exposed to sound to be converted into other signals.
Our co-pending U.S. patent application Ser. No. 09/246,967, filed Feb. 9, 1999 concerns using features of mechanical impedance in achieving refinements to geometry and/or location(s) of bending wave transducer means for such panel members as or in acoustic devices. The contents of application Ser. No. 08/707,012 and 09/246,967 are hereby incorporated herein to any extent that may be useful in or to explaining, understanding or defining the present invention. These applications are collectively referred to herein as the “two prior patent applications.”
This invention arises particularly in relation to active acoustic devices in the form of loudspeakers using panel members to perform generally as above (and as may be called distributed mode acoustic radiators/resonant panels later herein), but further particularly achieve satisfactory combination of pistonic action with bending wave action. However, more general or wider aspects of invention arise, as will become apparent.
SUMMARY OF THE INVENTION
From a first viewpoint, this invention concerns active acoustic devices relying on bending wave action in panel members, particularly providing effective placement(s) for bending wave transducer means different from specific teachings of the two prior patent applications, i.e. other than at location(s) arising from analysis and preference in that parent application Ser. No. 08/707,012, even including at centre(s) of mass and/or geometry rather than off-set therefrom.
From a second viewpoint, this invention concerns acoustic devices relying on bending wave action in panel members, particularly providing effective distributions of resonant mode vibration that may be different from what results from specific teachings and preferences of the two prior patent applications even for the same configurations or geometries.
From a third viewpoint, this invention concerns acoustic devices relying on bending wave action in panel members, particularly providing effective distributions of resonant mode vibration in panel members of different configurations or geometries from what are regarded as inherently favourable in specific teachings and preferences of the two prior patent applications.
It is considered useful to note that effective specific embodiments of this invention utilise panel member(s) intrinsically affording areal distribution of resonant mode vibration components effective for acoustic performance generally comparable or akin to the two prior patent applications, essentially, relying on simple excitement of such intrinsically a really distributed acoustic bending wave action for successful acoustic operation; rather than in any way resembling merely piece-meal provisions for altering intendedly other acoustic action in panel member(s) for which such intrinsic distributed resonant mode action is not even a design requirement indeed, usually where other particular structural etc provisions are made to serve different frequency ranges and/or selectively suppress or specifically produce/superpose vibrations in a panel member that is not intrinsically effective as in two prior patent applications or herein, typically being inherently unsuitable as a matter of geometry and/or location of transducer means.
Effective inventive method and means hereof involve areal distribution of variation in stiffness over at least area(s) of such panel member(s) that are acoustically active in relation to bending wave action and desired acoustic operation. As will become clear herein, such variation can usefully be directly related effectively to displacement of transducer means from locations as specifically taught in the two prior patent applications to different locations of this invention, and/or, relative to such patent applications, to rendering unfavourable configurations or geometries of panel members more akin to favourable configurations or geometries for acoustic operation involving areal distribution of resonant modes of vibration consequential to bending wave action, and/or with actual resonant mode distribution that may be at least somewhat different, whether due simply to different areal distribution of bending stiffness hereof or to consequential different location(s) for transducer means, or both.
Specific teaching of parent application Ser. No. 08/707,012 extends to panel member(s) having different bending stiffness(es) in different directions across intendedly acoustically active area(s) that may be all or less than all of area(s) of the panel member(s), typically in or resolvable to two coordinate related directions, and substantially constant therealong. In contrast, advantageous panel member(s) of embodiment(s) hereof have variation of bending stiffness(es) along some direction(s) across said area(s) that is/are irresolvable to constancy in normal coordinate or any direction(s).
Areal variation of bending stiffness is, of course, readily achieved by variation of thickness of acoustic panel members, but other possibilities arise, say concerning thickness and/or density and/or tensile strength of skins of sandwich-type structures and/or reinforcements of monolithic structures usually of composite material(s) type.
Whilst available practical analysis may not always allow such investigation as precisely and fully to identify and quantify changes in actual areal distribution of acoustically effective resonant mode vibration for panel member(s) hereof—even where having substantially similar geometry and/or average stiffnesses in relevant directions as for specific isotropic or anisotropic embodiments per parent application Ser. No. 08/707,012—practical resulting performance indicates little if any significant diminishing or degradation in achieved successful acoustic performance involving bending wave action, indeed encourages belief in potential even for improving same. Beneficial effects (on areal distribution of resonant mode vibration), of basically favourable configuration/geometry of the tow prior patent applications can, however, be substantially retained to very useful extent and effect in two groups or strands of inventive aspects implementing above one viewpoint.
One group/strand is as already foreshadowed, specifically providing more convenient location(s) for transducer means in acoustically active panel members or areas thereof having configurations

Affiliated with

Also associated with

Rating

Acoustic device does not yet have a rating. At this time, there are no reviews or comments for this patent.

If you have personal experience with Acoustic device, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Acoustic device will most certainly appreciate the feedback.

Rate now

Comments { 0 }

Profile ID: LFUS-PAI-O-2486442