Electrical audio signal processing systems and devices – Electro-acoustic audio transducer – Plural or compound reproducers
Reexamination Certificate
1999-09-17
2001-11-27
Kuntz, Curtis (Department: 2643)
Electrical audio signal processing systems and devices
Electro-acoustic audio transducer
Plural or compound reproducers
C381S087000, C381S398000, C381S431000, C181S287000, C181S288000, C181S292000
Reexamination Certificate
active
06324294
ABSTRACT:
TECHNICAL FIELD
The invention relates to passenger vehicles and more particularly to passenger vehicles incorporating loudspeakers comprising panel-form acoustic radiating elements.
BACKGROUND ART
Embodiments of the present invention use members of nature, structure and configuration achievable generally and/or specifically by implementing teachings of our parent 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 exciter 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.
Members as above are herein called distributed mode acoustic radiators and are intended to be characterised as in the above parent application Ser. No. 08/707,012 and/or otherwise as specifically provided herein.
This invention is particularly concerned with acoustic devices in the form of resonant acoustic radiator loudspeakers for use in passenger vehicles such as automobiles, aircraft, boats, railway trains etc, and to vehicles incorporating such loudspeakers.
DISCLOSURE OF INVENTION
The invention is a vehicle having a passenger compartment characterised by a loudspeaker in the passenger compartment comprising a distributed mode acoustic radiator and an exciter mounted on the radiator to vibrate the radiator to cause it to resonate.
The radiator may be integral with a passenger seat in the vehicle or with a door into the passenger compartment. The radiator may be integral with the interior of the passenger compartment, e.g. a wall, floor or roof. Thus the radiator may be integral with a roof lining in an automobile or the like. A plurality of such radiators may be arranged in the vehicle.
The vehicle may comprise a plastics or fibrous moulded component in or forming part of the passenger compartment, and the radiator may be integral with the component.
The radiator may comprise a stiff lightweight panel having cellular core sandwiched between skin layers, and wherein one of the skins is integral with the moulded component. The said one skin may be thin in comparison to the average wall thickness of the component. The said one skin may be surrounded by a groove or slot in the component, the groove defining a resilient surround for the radiator, and the slot helping to define a region of distributed mode bending operation.
From another aspect, the invention is a vehicle component comprising a loudspeaker having a distributed mode acoustic radiator and an exciter mounted on the radiator to vibrate the radiator to cause it to resonate.
Employing the principle for the distributed mode loudspeaker described in our parent application Ser. No. 08/707,012, it is possible to employ suitable existing structures, directly or by adaptation or modification, or by original design, to operate as effective loudspeakers.
Distributed mode operation indicates that a beneficial spread of modal resonances be encouraged in a structure intended to operate as an acoustic radiator. The principle teaches properties of structure, geometry and driving point(s) which promote good modal density for wide range sound reproduction. Some structures e.g. existing or prefabricated or similar panels may naturally have such a property in the frequency range of interest, for which a suitable mathematical and mechanical analysis will determine the optimum driving point(s) and exciter(s) and their characteristics for a useful acoustic output.
Obviously where existing or installed structures are appropriate there is potentially high convenience, utility and decorative value and additionally a cost benefit for additional operation/inclusion of a loudspeaker, whether for music or speech application for example hands-free mobile telephony to enhance safety. Such class of speaker provides weight saving and/or greater impact safety for the vehicle occupants.
Subject to structural and acoustic analysis including the effect of the potential air load, an existing interior door panel or parcel shelf or equivalent or roof lining may benefit from modification to its mountings or the addition of stiffening members, sections or panels, to result in a performance closer to the intended distributed mode form, in the intended range of operation.
Alternatively these panel units, compatible or otherwise with existing practice, may be structured and designed to possess distributed mode potential for general vehicular interiors even having the dimensions of small rooms e.g. rail coaches, buses etc. according to the principles described in parent application Ser. No. 08/707,012.
For automotive use the distributed mode principle is particularly suited since the acoustic element may be robust, water and environmentally resistant and requires no grill cover or opening, or protection for its effective operation. In fact the acoustic part of the panel may be fully integrated such that no external witness of its presence is required this also for interior design where the visual presence of loudspeaker systems is to be avoided.
Where sound systems are incorporated in vehicles, the distributed mode principle allows them to be fully integrated in prefabricated units including related services such as rooflights and related control and display technology served by as little as one wiring harness for reduced assembly cost. In additional the integration of more advanced facilities in, for example, a vehicle roof lining, adds engineering value to this product.
While distributed mode speakers are capable of, and are generally designed to operate over, a wide frequency range, in particular uniquely to reach to the highest audible frequencies without the use of additional drive elements or crossover networks, some panel structures lend themselves to effective operation in the lower frequency range owing to their relatively low fundamental bending frequency. While employing built-in or otherwise distributed mode speaker elements for the usual middle and upper frequency range, the naturally low bending frequency(s) for the structural or modular panels in question may be utilised for sound reproduction which is optimised in the low frequency range to work congruently with the upper range units. The result is a beneficial additional operation of such panel as dual purpose while the low frequency range may extend into the range generally covered by box type units called subwoofers, characterised by operation in the range below 150 Hz and which may extend down to audible 20 Hz limits or thereabouts, this lower limit still sensed by human perception and capable of enhancing the enjoyment of reproduced music signals of wide recorded bandwidth. Larger structural panels of heavier construction of resin bonded composites of combinations of these and similar material will have modal resonances extending to the low range and may be driven by a number of electromagnetic energisers including those designed specifically to suit distributed mode loudspeakers as described in our copending application Ser. Nos. 09/011,773, 09/011,770 and 09/011,831 optimised by driving force and natural resonance to couple well to larger heavier panels.
The integration of sound systems with vehicle design, also with lighting units is an important aspect of modern practice. The distributed mode speaker principle is uniquely suited to these applications where unobtrusive even totally concealed sound systems may be designed. Full range types of loudspeakers, resonant panel or otherwise, may be augmented by resonating distributed mode panels which are designed to be effective in the low range.
Azima Henry
Colloms Martin
Ellis Christien
Foley & Lardner
Harvey Dionne N.
Kuntz Curtis
New Transducers Limited
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